# High-resolution, High-sensitivity, Low-frequency uGMRT View of Coma Cluster
of Galaxies

D. V. Lal National Centre for Radio Astrophysics - Tata Institute of
Fundamental Research Post Box 3, Ganeshkhind P.O., Pune 411007, India  N.
Lyskova Space Research Institute (IKI), Profsoyuznaya 84/32, Moscow 117997,
Russia  ASC of P.N.Lebedev Physical Institute, Leninskiy prospect 53, Moscow
119991, Russia  C. Zhang Department of Astronomy and Astrophysics, The
University of Chicago, Chicago, IL 60637, USA  T. Venturi INAF - Istituto di
Radioastronomia, via Gobetti 101, I-40129 Bologna, Italy  W. R. Forman
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge,
Massachusetts 02138, USA  C. Jones Harvard-Smithsonian Center for
Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA  E. M.
Churazov Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1,
85741 Garching, Germany  Space Research Institute (IKI), Profsoyuznaya 84/32,
Moscow 117997, Russia  R. J. van Weeren Leiden Observatory, Leiden University,
PO Box 9513, 2300 RA Leiden, The Netherlands  A. Bonafede DIFA - Universitá di
Bologna, via Gobetti 93/2, I-40129 Bologna, Italy  INAF - Istituto di
Radioastronomia, via Gobetti 101, I-40129 Bologna, Italy  Universität Hamburg,
Hamburger Sternwarte, Gojenbergsweg 112, D-21029, Hamburg, Germany  N. A.
Miller Stevenson University, Department of Mathematics and Physics, 1525
Greenspring Valley Road, Stevenson, MD, 21153, USA  I. D. Roberts Leiden
Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
A. M. Bykov Ioffe Institute, Politekhnicheskaya st. 26, Saint Petersburg
194021, Russia  L. Di Mascolo Dipartimento di Fisica dell’ Universitá di
Trieste, Sezione di Astronomia, via Tiepolo 11, I-34131 Trieste, Italy  M.
Brüggen Universität Hamburg, Hamburger Sternwarte, Gojenbergsweg 112, D-21029,
Hamburg, Germany  G. Brunetti INAF - Istituto di Radioastronomia, via Gobetti
101, I-40129 Bologna, Italy

(Received 5 April 2022; Accepted 18 June 2022)

###### Abstract

We present high-resolution, high-sensitivity upgraded Giant Metrewave Radio
Telescope observations of the Coma cluster (A1656) at 250-500 MHz and 550-850
MHz. At 250-500 MHz, 135 sources have extensions $>0\farcm 45$ (with peak-to-
local-noise ratio $>4$). Of these, 24 sources are associated with Coma-member
galaxies. In addition, we supplement this sample of 24 galaxies with 20 ram
pressure stripped (RPS) galaxies from Chen et al. (2020, eight are included in
the original extended radio source sample) and an additional five are detected
and extended. We present radio morphologies, radio spectra, spectral index
maps, and equipartition properties for these two samples. In general, we find
the equipartition properties lie within a narrow range (e.g., $P_{\rm min}$ =
1–3 dynes cm-2). Only NGC 4874, one of the two brightest central Coma cluster
galaxies, has a central energy density and pressure about five times higher
and a radio source age about 50% lower than that of the other Coma galaxies.
We find a diffuse tail of radio emission trailing the dominant galaxy of the
merging NGC 4839 group that coincides with the slingshot tail, seen in X-rays.
The southwestern radio relic, B1253$+$275, has a large extent $\approx$ 32′
$\times$ 10′ ($\simeq$ 1.08 $\times$ 0.34 Mpc2). For NGC 4789, whose long
radio tails merge into the relic and may be a source of its relativistic seed
electrons, and we find a transverse radio spectral gradient, a steepening from
southwest to northeast across the width of the radio source. Finally, radio
morphologies of the extended and RPS samples suggest that these galaxies are
on their first infall into Coma on (predominantly) radial orbits.

Active galactic nuclei (16), Astrophysical black holes (98), Galaxy clusters
(584), High energy astrophysics (739), Intracluster medium (858), Radio
continuum emission (1340), Radio galaxies (1343), Supermassive black holes
(1663), Tailed radio galaxies (1682), X-ray active galactic nuclei (2035)

##  1 Introduction

The rich galaxy cluster Abell 1656 (A1656; Abell, 1958; Abell, Corwin &
Olowin, 1989) in the constellation Coma Berenices is one of a trio (with the
Perseus and Virgo clusters) of the most intensively studied clusters. Coma is
nearby (z = 0.0232; Wagner et al., 1999), massive (6 $\times$ 1014
$M_{\odot}$; Planck Collaboration, 2013), regular, dominated by E and S0
galaxies, and lies near the Galactic pole ($b^{II}=88^{\circ}$), away from any
significant obscuration, which make it an ideal target across the wavelength
band. Unlike the other members of the cluster trio, Coma appears relatively
spherical, and therefore, more amenable to many types of studies that have
dramatically advanced our understanding (e.g., Zwicky, 1933). The
concentration of nebulae in Coma was first noted by Herschel (1785). The first
ADS listing for Coma is the study of Curtis (1918), who remarked that the
region “contains the most remarkable aggregation of closely packed small
nebulae”. Over the past 100 yr, Coma has been observed by nearly every major
telescope across the electromagnetic spectrum, and it is now considered a
cluster where merging processes are currently taking place (see Churazov et
al., 2021, for a recent overview). Among the newest probes of the Coma cluster
are those from the Fermi-LAT. Based on 12 yr of Fermi-LAT data, Adam et al.
(2021) and Baghmanyan et al. (2021) have recently reported emission at
$\gamma$-ray energies from the direction of the Coma cluster. This emission
could arise from interactions of the thermal gas with relativistic protons.
Models of cosmic-ray acceleration by multiple large-scale shocks, which heat
the intracluster gas (see also Bykov et al., 2019, for review), predict
cosmic-ray proton distribution power-law indices consistent with the reported
values. While secondary leptons produced by cosmic-ray protons may produce
radio synchrotron emission, their contribution and the relative contribution
of point sources to this emission is an open issue (see also Brunetti, &
Lazarian, 2011, 2016; Pinzke, Oh & Pfrommer, 2017, for a detailed discussion).

Table 1: Summary of recent wide-area radio observations of the Coma cluster. Frequency | Area | Resolution | Sensitivity
---|---|---|---
| (deg2) | (${\prime\prime}$) | ($\mu$Jy beam-1)
(1) | (2) | (3) | (4)
JVLA |  |
2051–3947 MHz† |  $\sim$0.2 | 15.1 | 151
1400 MHz‡ |  $\sim$0.5 | 4.4 | 22
uGMRT |  |
250–500 MHz |  $\sim$4.0 | 6.0 | 31.1
550–850 MHz |  $\sim$3.8 | 3.5 | 16.4
Lofar |  |
144 MHzϝ |  $\sim$25 | 20 | 150

Previous radio continuum studies of Coma were both pioneering, uncovering new
phenomena, and very comprehensive (see Table 1 for a summary of previous
large-area surveys that are most recent and comparable to our uGMRT data
presented here). Coma is the first cluster where diffuse steep spectrum
megaparsec-scale low-surface brightness emission in the form of a radio halo
and a relic was discovered (Willson, 1970); (see also Brunetti & Jones, 2014;
van Weeren et al., 2019, for recent reviews on this topic). It is also the
first cluster, where a bridge of emission connecting the halo and the relic
was found (Kim et al., 1989). Both the radio halo and relic have been
extensively studied with all radio interferometers (i.e., Venturi, Giovannini
& Feretti, 1990; Giovannini, Feretti & Stanghellini, 1991; Giovannini et al.,
1993; Brown & Rudnick, 2011; Bonafede et al., 2021) and are considered the
prototypes for these classes of cluster radio sources. Coma further hosts a
number of head-tail and wide-angle-tail radio galaxies (see Feretti & Venturi,
2002), which have been studied in the context of the interaction between the
radio-emitting plasma of the jets and lobes and the surrounding environment
(i.e., Venturi, Feretti & Giovannini, 1989; Feretti et al., 1990; Kim et al.,
1994; Lal, 2020a, b). Finally, radio continuum tails of ram pressure stripping
origin have been recently reported for a number of late-type galaxies (Miller,
Hornschemeier & Mobasher, 2009; Chen et al., 2020; Roberts et al., 2021).

In this work, we present observations of the Coma cluster at low frequencies
obtained with the upgraded Giant Metrewave Radio Telescope (uGMRT; Swarup et
al., 1991; Gupta et al., 2017). Our observations are made in the frequency
bands 250–500 MHz and 550–850 MHz at angular resolutions of $\sim$6$\farcs$1
and $\sim$3$\farcs$7, respectively, and cover approximately $\approx$7.5 deg2
using both new and archival pointings (see Table 2 and Fig. 1). As Table 1
shows, the uGMRT survey we present has better sensitivity and angular
resolution than the public LOFAR survey and better sensitivity, larger solid
angle, and better resolution than the JVLA Coma survey. For these reasons, we
concentrate on the uGMRT data for this paper.

Table 2: The uGMRT observations. Field | Obs_ID | Obs. Date | $\nu$ | $\Delta\nu$ | Ch./Ch.-width | tint. | FWHM | rms
---|---|---|---|---|---|---|---|---
|  |  | (MHz) | (MHz) | (no. / kHz) | (hr) | (${}^{\prime\prime}\times^{\prime\prime},^{\circ}$) | ($\mu$Jy beam-1)
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9)
250–500 MHz |  |  |  |  |  |  |
Coma C | ddtB270 | 2017-04-28 | 400 | 200 | 4096 / 48.8 | 1.8 |  6.65$\times$5.90, 76.39 |  21.1
NGC 4839 | 36_033 | 2019-05-12 | 400 | 200 | 8192 / 24.4 | 3.9 |  6.31$\times$5.73, 50.61 |  31.1
NGC 4789 | 36_033 | 2019-05-23 | 400 | 200 | 8192 / 24.4 | 4.7 |  6.51$\times$5.66, 41.27 |  36.1
550–850 MHz |  |  |  |  |  |  |
NGC 4839 | 36_033 | 2019-06-14 | 700 | 300 | 8192 / 48.8 | 3.4 |  4.21$\times$3.30, 71.82 |  19.8
NGC 4789 | 36_033 | 2019-06-14 | 700 | 300 | 8192 / 48.8 | 3.0 |  4.04$\times$3.35, 64.58 |  15.5
B1253$+$275-N | 36_033 | 2019-06-13 | 700 | 300 | 8192 / 48.8 | 2.3 |  3.89$\times$3.58, 37.69 |  42.4
B1253$+$275-S | 36_033 | 2019-05-31 | 700 | 300 | 8192 / 48.8 | 1.8 |  4.45$\times$3.44, 45.55 |  13.7
B1253$+$275-NW | 36_033 | 2019-05-31 | 700 | 300 | 8192 / 48.8 | 1.7 |  4.30$\times$3.42, 44.01 |  18.6
B1253$+$275-SE | 36_033 | 2019-06-13 | 700 | 300 | 8192 / 48.8 | 1.8 |  3.96$\times$3.44, 66.10 |  16.5
Coma H | 35_005 | 2018-01-01 | 700 | 300 | 2048 / 195.3 | 2.2 |  3.74$\times$3.16, 44.79 |  12.8
Coma L | 35_005 | 2018-01-01 | 700 | 300 | 2048 / 195.3 | 1.3 |  3.69$\times$3.08, 40.73 |  16.4

We have used the deepest radio images of the Coma cluster in the 250-500 MHz
and 550-850 MHz bands to image the extended cluster radio galaxies and study,
for the first time, using a radio-selected sample, the connection between the
orientation and intrinsic properties of the tails and the cluster environment,
as did Roberts & Parker (2020) for an optically selected sample of ram
pressure stripped (RPS) galaxies (see also Roberts et al. (2021) who studied a
Sloan Digital Sky Survey (SDSS)-high star formation rate sample of jellyfish
galaxies). As Table 1 shows, the uGMRT observations provide the highest
sensitivity observations over a large field which themselves are adequate for
our analysis. Future papers focusing on individual radio sources and
structures will exploit radio observations at other wavelengths. In this
paper, we investigate whether the extended radio galaxies in the cluster bear
information on the cluster dynamics and accretion processes that are taking
place, making use of head-tail and wide-angle-tail radio sources, associated
with elliptical galaxies and RPS sources, associated with late-type galaxies.
To this aim, we use both the radio continuum images as well as spectral
imaging in the frequency range covered by our observations.

The paper is organized as follows: Our data are summarized in Sec. 2. Sec. 3
discusses our 24 extended radio sources and 20 RPS galaxies that are
associated with the Coma cluster. We present the analyses of our data, i.e.,
radio morphologies and spectral structure in Sec. 4.1 and in Sec. 4.1.1 for
extended radio sources, and in Sec. 4.2 and Sec. 4.2.1 for RPS galaxies,
respectively. Descriptions of the radio morphologies and optical properties of
these extended sources, along with notes from the literature, are given in the
Appendices (Sec. A.1 and A.2). We also provide notes on the spectral structure
of four large angular-sized sources in the Appendix (Sec. A.1.1). In Sec. 5,
we examine the nature of radio morphologies of cluster-member galaxies,
including equipartition parameters and radiative ages of all extended and
detected RPS galaxies (Sec. 5.2), their relative motions with respect to the
cluster center (Sec. 5.3), and their X-ray properties (Sec. 5.4). Sec. 6
summarizes our conclusions.

Throughout this paper, we adopt a $\Lambda$ cold dark matter cosmology with
$H_{0}$ = 70 km s-1 Mpc-1, $\Omega_{\rm m}$ = 0.27, and $\Omega_{\Lambda}$ =
0.73. At the mean redshift of the Coma cluster, $z$ = 0.02316, 1 arcsec
corresponds to 467 pc at the luminosity distance of 100.7 Mpc. We define the
spectral index, $\alpha$, as $S_{\nu}$ $\propto$ $\nu^{\alpha}$; where
$S_{\nu}$ is the flux density at frequency, $\nu$. Throughout, positions are
given in J2000 coordinates.

---
Figure 1: Mosaic image of three pointings (see Table 2) at an angular
resolution of $\sim$6$\farcs$1 in the uGMRT 250–500 MHz band. Source positions
are marked by the ‘$+$’ sign and color coded according to their redshifts,
where blue marks the lowest redshift (= 0.01523) galaxy, red marks the highest
redshift (= 0.03707) galaxy, and the intervening galaxies are marked with
increasing gradient from smaller (blue) to higher (red; see also Fig. 2). The
source_IDs are also labeled adjacent to their positions, extended sources (in
blue) and the RPS galaxies (in dark-red) that are members of Coma are listed
in Tables 3 and 4, respectively. The magenta points mark the peak positions of
dominant (peak $S_{\nu}$ $\gtrsim$ 30 mJy beam-1 at 250–500 MHz band) radio
emission. The grayscale image is displayed in logarithmic scales to emphasize
the extended, low-surface brightness diffuse radio emission and radio emission
associated with the radio galaxies. The pointing containing Coma A has higher
rms noise ($\approx$36 $\mu$Jy beam-1) than the other pointings (see Table 2
for rms noise levels). Note the starry-pattern artifact centered on Coma A,
limiting the dynamic range that could be achieved for the NGC 4789 data. Eight
circles correspond to the eight pointings in the uGMRT 550–850 MHz band (see
Table 2).

##  2 Observations and Data Reduction

###  2.1 Radio Data

The GMRT (Swarup et al., 1991) has been upgraded with a completely new set of
receivers at frequencies $<$ 1.5 GHz. The uGMRT has (nearly) seamless
frequency coverage in the 0.050–1.50 GHz range (Gupta et al., 2017). The data
reported here include archival data (Obs_IDs” DDT-ddtb270 and 35_005) and new
observations (Obs_ID 36_033) detailed in the observation log (Table 2). As far
as possible, two pointings were observed alternately for one observing run,
each integration lasting $\sim$20 minutes. Before and after two scans,
corresponding to two pointings, a calibration source, 3C 286 was observed for
$\sim$5 minutes. In this way, a fairly regular and complete sampling of the
($u,v$) plane was obtained.

---
Figure 2: The background-subtracted, exposure, and vignetting-corrected XMM-
Newton image of the Coma cluster in the 0.5–2.5 keV energy band. The positions
of the extended radio sources (Table 3) and the RPS galaxies (Table 4) are
marked with circles and boxes, respectively. The source name and their
positions are color coded according to redshifts, where blue marks the lowest
redshift (= 0.01523) galaxy, red marks the highest redshift (= 0.03707)
galaxy; the intervening galaxies are marked with increasing gradient from
smaller (blue) to higher (red) as depicted in the inset redshift scale bar.

Both the archival and new uGMRT data were analysed in aips and casa, using
standard imaging procedures (see also Lal, 2020a, for a complete and detailed
description of the data reduction methodology). Briefly, after bad data were
edited, phases and amplitudes were calibrated using the calibration source
observations. The flux density calibrator, 3C 286 was used as the secondary
phase calibrator during the observations. We used the calibration source to
correct for the bandpass shape and to set the flux density scale (Perley &
Butler, 2017). Bad data and data affected due to RFI were identified and
flagged. After the initial calibration, the 200 MHz wide data of the 250–500
MHz band and the 300 MHz wide data of the 550–850 MHz band were split into
five 40 MHz and six 50 MHz sub-bands, respectively. For each pointing, a
region of size $\approx$ 3∘ $\times$ 3∘ and $\approx$ 1.8∘ $\times$ 1.8∘ was
imaged, at 250–500 MHz and 550–850 MHz, respectively, extending far beyond the
null of the GMRT primary beam. In addition to the standard self-calibration
procedure, the method of peeling was also performed, in aips, on each sub-band
to correct for direction-dependent errors. The calibrated data for five 40 MHz
and six 50 MHz sub-bands were further stitched to form full 200 and 300 MHz
calibrated visibility data at the two uGMRT bands, 250–500 MHz and 550–850
MHz, respectively. Next, these combined visibilities were imaged using tclean
in casa. We used 3D imaging (gridder = ‘widefield’), two Taylor coefficients
(nterms = 2), and Briggs weighting (robust = 0.5) in tclean to ensure image
fidelity over the full field of view and wide band. A final amplitude and
phase self-calibration with a solution interval equal to the length of
observation was then applied, and the two polarizations, RR and LL, were
combined to obtain the final image. The final image was corrected for the
primary beam shape of the GMRT antennas. The uncertainty in the estimated flux
density, both due to calibration and due to systematics is $\lesssim$5 per
cent (see also Lal, 2020a).

These final images have a noise level (from a portion of an image at the half
power points) of 21.1–36.6 $\mu$Jy beam-1 and 12.8–42.4 $\mu$Jy beam-1 at the
angular resolutions of $\sim$6$\farcs$1 and $\sim$3$\farcs$7 in the 250–500
MHz and 550–850 MHz bands, respectively (see Table 2). These are the deepest
images so far reported at these bands covering a total area of $\sim$4 deg2,
despite the modest integration time ($\approx$2.5 hr on sky for a typical
pointing). The (conservative) uncertainty in the estimated flux density, both
due to calibration and due to systematics, is $\lesssim$4% at both 250–500 MHz
and 550–850 MHz bands. The rms noise is a factor of $\approx$2 and 3 higher
close to the dominant radio sources, NGC 4874 (one of the two core BCGs) and
Coma A, respectively. Based on the range for the brightest pixels (in the
three 250–500 MHz band pointings and the eight 550–850 MHz band pointings),
i.e., 0.71–0.61 Jy beam-1 and 0.23–0.02 Jy beam-1, we reach dynamic ranges of
$\sim$20,000:1–29,000:1 and $\sim$5,500:1–15,700:1 in the 250–500 MHz and
550–850 MHz bands, respectively, considering that a pointing contained the
very bright Coma A radio source. The three corrected primary beam pointings at
250–500 MHz band were knitted together and are presented in Fig. 1. Also shown
are eight circles that correspond to the eight pointings at 550–850 MHz. Note
that the two mosaics were not affected by an offset with respect to the phase
center, since the images revealed (i) no systematic differences besides
typical differences in flux density calibration, and (ii) no positional
offsets that are larger than the size of a pixel ($\approx$0.05 arcsec and
$\approx$0.03 arcsec at 250–500 MHz and 550–850 MHz bands, respectively).

###  2.2 X-Ray Data

Table 3: Radio Properties of the 24 Extended Coma Cluster-member Sources Detected using the uGMRT. Source_ID | Optical Position | $z$ | rms | $S_{\rm 400MHz}$ | $S_{\rm 700MHz}$ |  | Radio
---|---|---|---|---|---|---|---
| R.A. | Decl. |  | B-3 | B-4 |  |  | $\alpha_{\rm 400MHz}^{\rm 700MHz}$ | Morphology
| (J2000) |  |  ($\mu$Jy b-1) | (mJy) |  |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10)
1 2MASX J12520684$+$2701352 | 12:52:06.84 |  $+$27:01:35.2 | 0.02135 | 12 | 24 |  3.3 $\pm$0.2 |  1.7 $\pm$0.1 |  $-$1.23 $\pm$0.13 | A
2 NGC 4789 | 12:54:19.02 |  $+$27:04:04.9 | 0.02790 | 40 | 24 |  156.8 $\pm$1.2 |  119.5 $\pm$0.5 |  $-$0.49 $\pm$0.02 | HT, NAT
3 Mrk 53 | 12:56:06.10 |  $+$27:40:41.2 | 0.01657 | 24 | 24 |  14.5 $\pm$0.4 |  9.5 $\pm$0.2 |  $-$0.75 $\pm$0.07 | T
4 NGC 4827 | 12:56:43.52 |  $+$27:10:43.7 | 0.02545 | 24 | 18 |  132.9 $\pm$0.5 |  101.2 $\pm$0.3 |  $-$0.49 $\pm$0.01 | CD, FR II
5 NGC 4839 | 12:57:24.35 |  $+$27:29:51.8 | 0.02456 | 36 | 18 |  196.9 $\pm$1.6 |  118.9 $\pm$1.0 |  $-$0.90 $\pm$0.02 | HT, WAT, cD
6 Mrk 55 | 12:57:25.25 |  $+$27:24:16.5 | 0.01620 | 24 | 12 |  7.9 $\pm$0.5 |  5.2 $\pm$0.3 |  $-$0.78 $\pm$0.14 | Tr
7 KUG 1255$+$283† | 12:57:57.75 |  $+$28:03:41.5 | 0.02768 | 24 | 18 |  17.3 $\pm$0.7 |  13.4 $\pm$0.4 |  $-$0.45 $\pm$0.08 | T
8 NGC 4848† | 12:58:05.58 |  $+$28:14:33.3 | 0.02351 | 24 | 24 |  60.7 $\pm$2.1 |  43.4 $\pm$0.8 |  $-$0.60 $\pm$0.07 | T
9 2MASX J12581865$+$2718387 | 12:58:18.62 |  $+$27:18:38.9 | 0.02484 | 24 | 18 |  10.7 $\pm$0.5 |  9.4 $\pm$0.2 |  $-$0.22 $\pm$0.10 | T
10 Mrk 56 | 12:58:35.34 |  $+$27:15:52.9 | 0.02458 | 12 | 12 |  7.3 $\pm$0.3 |  7.8 $\pm$0.1 |  0.11 $\pm$0.08 | T
11 Mrk 57 | 12:58:37.28 |  $+$27:10:35.8 | 0.02556 | 18 | 24 |  14.4 $\pm$0.4 |  8.9 $\pm$0.2 |  $-$0.86 $\pm$0.05 | T
12 IC 3949† | 12:58:55.95 |  $+$27:50:00.4 | 0.02525 | 18 | 12 |  7.5 $\pm$0.3 |  5.3 $\pm$0.2 |  $-$0.61 $\pm$0.10 | A, T
13 NGC 4858† | 12:59:02.07 |  $+$28:06:56.4 | 0.03141 | 36 | 12 |  22.1 $\pm$0.7 |  12.1 $\pm$0.5 |  $-$1.07 $\pm$0.10 | T
14 Mrk 58† | 12:59:05.30 |  $+$27:38:39.9 | 0.01853 | 24 | 24 |  12.2 $\pm$0.6 |  7.9 $\pm$0.3 |  $-$0.76 $\pm$0.11 | T
15 NGC 4869 | 12:59:23.33 |  $+$27:54:41.8 | 0.02288 | 72 | 36 |  1381.0 $\pm$9.7 |  735.9 $\pm$2.1 |  $-$1.12 $\pm$0.01 | HT, NAT
16 NGC 4874 | 12:59:35.71 |  $+$27:57:33.8 | 0.02394 | 384 | 96 |  476.6 $\pm$2.3 |  305.0 $\pm$2.4 |  $-$0.80 $\pm$0.02 | HT, NAT, cD
17 2MASX J12594009$+$2837507ϝ | 12:59:40.10 |  $+$28:37:50.8 | 0.01787 | 12 | $-$ |  4.5 $\pm$0.1 | $-$ | $-$ | A
18 2MASX J13001780$+$2723152ϝ | 13:00:17.81 |  $+$27:23:15.1 | 0.03707 | 24 | $-$ |  16.3 $\pm$0.1 | $-$ | $-$ | A, D
19 KUG 1258$+$279A† | 13:00:33.73 |  $+$27:38:15.6 | 0.02494 | 24 | 12 |  10.5 $\pm$0.6 |  7.0 $\pm$0.2 |  $-$0.74 $\pm$0.11 | T
20 IC 4040† | 13:00:37.86 |  $+$28:03:28.7 | 0.02615 | 24 | 12 |  53.3 $\pm$1.5 |  29.6 $\pm$0.3 |  $-$1.05 $\pm$0.05 | T
21 2MASX J13004067$+$2831116ϝ | 13:00:40.68 |  $+$28:31:11.6 | 0.02969 | 24 | $-$ |  18.2 $\pm$0.5 | $-$ | $-$ | T
22 2MASX J13004385$+$2824586 | 13:00:43.88 |  $+$28:24:58.8 | 0.02095 | 24 | 24 |  31.6 $\pm$0.6 |  16.4 $\pm$0.2 |  $-$1.17 $\pm$0.04 | HT, WAT
23 NGC 4911† | 13:00:56.06 |  $+$27:47:27.2 | 0.02663 | 24 | 12 |  50.6 $\pm$1.0 |  29.2 $\pm$0.2 |  $-$0.98 $\pm$0.04 | A
24 NGC 4927ϝ | 13:01:57.59 |  $+$28:00:21.0 | 0.02590 | 18 | $-$ |  9.9 $\pm$0.7 | $-$ | $-$ | WAT

The Coma cluster has been observed multiple times with Chandra and XMM-Newton.
Lyskova et al. (2019) presented an anaylsis of XMM-Newton data from the
EPIC/MOS detector, covering a field of more than 1 deg2 (see Fig. 2). The data
were analysed by removing background flares using the light curve of the
detected events and renormalizing the ‘blank fields’ background to match the
observed count rate in the 11–12 keV band (shown in Fig. 2, Churazov et al.,
2003).

To investigate the interaction of the radio lobes of one of two core bright
cluster galaxies (BCGs), NGC 4874 with its environment, we used Chandra
observations (Obs_IDs 13993 13994, 13995, 13996, 14406, 14410, 14411, and
14415). These data were selected since they are nearly contemporaneous (within
one month in 2012) and do not suffer from varying ACIS responses. The
accumulated data is about 400 ks. The data were analysed following the steps
described in Vikhlinin et al. (2005), which include filtering of high
background, use of the latest calibration corrections, and determination of
the background for each observation. The image in the 0.5–4.0 keV band was
generated along with the exposure and background maps (see Churazov et al.,
2012, for details).

##  3 Extended Radio Sources and RPS Galaxies

The Coma cluster has been studied over the years, providing a vast amount of
literature. Using an extensive survey, Huchra et al. (1990) and Kent & Gunn
(1982) compiled a list of redshifts between blue band magnitude 10.94 and
21.63 in the Coma cluster and its surrounding environs to a radius of six
degrees from NGC 4874, one of the two core BCGs of the Coma cluster, for
galaxies whose radial velocities are in the range betweeb 4000 and 9400 km
s-1, considered to be associated with the Coma cluster. We have used this
catalog to identify cluster-member galaxies.

A search of the 250–500 MHz image was made to find the position and flux
densities of all strong (point and extended) sources. These were then
“blanked” from the map to enable searches for weaker sources. Preliminary
inspection suggests a myriad ($\simeq$ 2000) of extended and point-like
discrete radio sources is seen in the image, most of them being background
active galactic nuclei (AGNs). The analysis of these detected (point and
extended) sources will be undertaken as separate projects.

---
Figure 3: Images of extended ($\gtrsim$12.6 kpc) confirmed Coma cluster-member
radio sources. These radio sources are in the order presented in Table 3, from
left to right and top to bottom. The source_ID, as tabulated in the Table 3,
is labeled in the lower-left corner of each image. The label at the lower-
right corner of each image is the source_ID for (eight) RPS galaxies as
tabulated in the Table 4. The magenta and blue radio contours correspond to
250–500 MHz (band 3) and 550–850 MHz (band 4) at angular resolutions of
6$\farcs$1 and 3$\farcs$7, respectively, of the uGMRT that are are overlaid on
the grayscale SDSS (DR12) $r$-band image. The lowest radio contour is three
times the local rms noise and subsequent contours increase by factors of 2.
The local rms noise is tabulated in Tables 3 and 4 for 250–500 MHz (Column 5)
and 550–850 MHz (Column 6) of the uGMRT. The grayscale images are displayed in
logarithmic scales to emphasize the optical hosts associated with the
respective radio galaxies.

The definition and identification of multiple systems, e.g., double lobes, is
a common problem in radio astronomy and is especially difficult for deep radio
observations. We therefore looked at images to find all obvious faint and/or
extended radio sources that are at least 4–5 beams across, i.e., sources
showing projected radio extent $\gtrsim$0$\farcm$45 ($\approx$ 12.6 kpc) at
the mean redshift of the Coma cluster down to a peak-to-local-noise ratio = 4
at an angular resolution of $\sim$6$\farcs$1 in the 250–500 MHz band image. We
have identified a total of 135 sources in the 250–500 MHz band. Of these, 31
sources were not covered in the 550–850 MHz band pointings. Furthermore, of
the 135 extended radio sources, half ($\approx$ 55 per cent) had redshift
measurements (as reported in the NED) and only 24 ($\approx$ 18 per cent) are
confirmed members of the Coma cluster. Note that we have not included the
historical Coma A (3C 277.3, $z$ = 0.08536) radio galaxy in this list. The
confirmed members of the Coma cluster have a redshift range from $z$ = 0.0162
(Mrk 55) to $z$ = 0.02969 (2MASX J13004067$+$2831116) around the mean Coma
cluster redshift $z$ = 0.02310.

All 20 RPS galaxies selected by Chen et al. (2020) from the combined galaxy
samples of Smith et al. (2010, UV trails), Yagi et al. (2010, 12 H$\alpha$),
Kenney, Abramson & Bravo-Alfaro (2015), and Gavazzi (1989), that are confirmed
members of the Coma cluster, are covered by our low-frequency radio
observations. Eight of our extended radio sources are also galaxies with RPS
tails of gas and embedded young stars (listed in both Tables 3 and 4). Of the
remaining 12 RPS galaxies, five are detected and seven are undetected in our
250–500 MHz band. Similarly, in the 550–850 MHz band, of these same 12 RPS
galaxies, three are detected and seven are undetected, and two are not covered
in our 550–850 MHz pointings. These are listed together in Table 4.

Tables 3 and 4 list these 24 extended radio sources and 20 RPS galaxies,
respectively, along with their source parameters. Since almost all the
extended radio sources have complex morphologies, we simply integrated the
signal within interactively defined boundaries and determined integrated flux
densities. Fig. 1 depicts the positions of the extended sources and RPS
galaxies, marked with ‘$+$’ signs, and color coded accordingly to their
redshifts (see Fig. 2). The source_IDs are also shown, (blue) numeric and
(red) alphabetic characters for extended sources and RPS galaxies,
respectively, adjacent to their positions. In Appendix (Sec. B) we present the
remaining 111 extended radio sources. Table A1 lists these 111 extended radio
sources and Fig. A1 depicts source_IDs and positions (magenta ‘$+$’ marks)
that are either foreground/background galaxies or do not have redshift data.
The radio images of these extended radio sources are presented in Fig. A2, in
the order listed in Table A1. Below we discuss, using our 250–500 MHz and
550–850 MHz band continuum (with deeper sensitivity) data on extended sources
and RPS galaxies in the Coma cluster.

##  4 Results and Analysis

###  4.1 Radio Morphologies of Extended Sources

In Table 3, we list 24 extended ($\gtrsim$12.6 kpc) radio sources that are
confirmed members of the Coma cluster. Individual columns are source_ID,
source position, spectroscopic redshift, rms noise at 250–500 MHz and 550–850
MHz in the near vicinity of the source, integrated flux densities at 250–500
MHz and 550–850 MHz, and the spectral index of the source using the 250–500
MHz and 550–850 MHz band flux densities. Uncertainties on the spectral index
are determined using uncertainties on the flux calibrations ($\lesssim$4%, see
also Sec. 2.1) and uncertainties on the flux densities, where the latter
correspond to the rms noise in the near vicinity of the source times the
square root of the number of beams covering the source in each observing band.
The source_IDs of the extended sources (in blue ‘$+$’ marks) are labeled
adjacent to their positions in Fig. 1 listed in Table 3.

---
Figure 4: Spectral index images of extended ($\gtrsim$12.6 kpc) radio sources
in the Coma cluster field that are imaged using 250–500 MHz band and 550–850
MHz band data at matched angular resolutions (= 8′′). The source_ID, as
tabulated in Tables 3 and 4, is labeled in the lower-left and lower-right
corners of each image. The optical host positions are marked by a ‘$+$’ sign.
These radio sources are in the order presented in Table 3, from left to right
and top to bottom. The images are displayed in linear scales, the scale bar
gives the spectral index range, and the typical spectral index uncertainty is
0.03. The magenta and blue radio contours (= five times the local rms noise)
are also overlaid, which correspond to the 250–500 MHz (band 3) and 550–850
MHz (band 4) data at the angular resolutions of 6$\farcs$1 and 3$\farcs$7,
respectively.

The radio images of these extended cluster-member radio sources are presented
in Fig. 3, in the order listed in Table 3. The source name, as tabulated in
the Table 3, is labeled in the lower-left corner of each image. The radio
contours, in magenta and blue, correspond respectively to the 250–500 MHz and
the 550–850 MHz band images that are overlaid on the grayscale SDSS (DR12)
$r$-band image. Descriptions of the radio morphologies and their optical
properties of these extended sources, along with notes from the literature,
are given in the Appendix (Sec. A). To study the plasma properties of these
extended sources, we also elaborate below on their radio morphologies (Sec.
A.1) and spectral properties (Sec. A.1.1) at low frequencies. For RPS galaxies
detected as extended sources, their alphabetic designation (as in Table 4) is
included along with the extended source serial number from Table 3 (see also
Sec. 4.2).

####  4.1.1 Spectral Structure of Extended Sources

---
Figure 4: Continued

Twenty of 24 extended sources were also covered in the 550–850 MHz band
pointings, which allows us to investigate the spectral index distribution of
these sources. Therefore, the final calibrated ($u,v$)-data at 550–850 MHz
were mapped using a ($u,v$)-taper of 0–36 k$\lambda$, which is similar to that
of the 250–500 MHz data and then restored, using the restoring beam
corresponding to the 250–500 MHz band image. We also made images at matched
lower angular resolutions to emphasize low-surface brightness diffuse
structures for both bands. The restored and matched images at the 250–500 MHz
and 550–850 MHz bands were further used to construct spectral index images for
20 of the 24 extended radio sources. The standard direct method, i.e., the
ratio of ${\rm log}\left[S_{\rm 400~{}MHz}(\rm x,y)/S_{\rm 700~{}MHz}(\rm
x,y)\right]$ and ${\rm log}\left[{\rm 400~{}MHz}/{\rm 700~{}MHz}\right]$,
where $S_{\rm 400~{}MHz}(\rm x,y)$ and $S_{\rm 700~{}MHz}(\rm x,y)$ are the
images at two bands, 250–500 MHz and 550–850 MHz, respectively, was used to
determine the spectral index distribution.

Fig. 4 shows spectral index images for 20 of the 24 extended radio sources
that are associated with the Coma cluster (in the order presented in Table 3).
The source_ID, as tabulated in Table 3, is labeled in the lower-left corner of
each image. All tailed radio sources are characterized by elongated
morphologies found in both bands of the uGMRT. As usual, sources that have a
high brightness head close to the optical galaxy and a narrow low brightness
tail show spectral structure that gradually steepens from the flat spectrum
head with increasing distance from the head along the tail. The prevalence of
flat spectrum radio cores in almost all extended radio sources implies that
they may still be active. These spectral trends are rather similar when the
uncertainties are taken into account for the majority of the extended radio
sources shown in Fig. 4.

---
Figure 5: Images of the five (of 20) RPS galaxies not detected as extended
radio sources. Eight RPS galaxies detected as extended radio sources are
presented in Fig. 3. The remaining seven RPS galaxies are not detected in our
low-frequency radio data. These radio sources are in the order presented in
Table 4, from left to right and top to bottom. The source_ID as tabulated in
the Table 4 (as alphabetical letters) is labeled in the lower-right corner of
each image. The magenta and blue radio contours correspond to 250–500 MHz
(band 3) and 550–850 MHz (band 4) at angular resolutions of 6$\farcs$1 and
3$\farcs$7, respectively, which are overlaid on the grayscale SDSS (DR12)
$r$-band image. The lowest radio contour plotted is three times the local rms
noise and increasing by factors of 2. The local rms noise is tabulated in
Table 4 for the 250–500 MHz band (Column 5) and 550–850 MHz band (Column 6) of
the uGMRT. The grayscale images are displayed in logarithmic scales to
emphasize the optical hosts associated with the respective radio galaxies.

The projected source size at lower frequencies, 250–500 MHz, is larger than
the source size at higher frequencies, the 550-850 MHz band, for all extended
sources presented here, probably due to synchrotron ageing. Note that the
integrated flux densities given in Table 3 for the 250–500 MHz and 550-850 MHz
band images are at angular resolutions of $\sim$6$\farcs$1 and
$\sim$3$\farcs$7, respectively. These measurements would neither affect the
small-angular sized radio sources nor affect the sources showing large angular
extent that have associated low-surface brightness diffuse radio emission,
namely, NGC 4789 and the associated relic radio source, 1253$+$275 in our
case, and NGC 4869. This is because our observations are full synthesis
observing runs at both bands, along with their large fractional bandwidths,
which result in good ($u,v$)-coverage at the short as well as the long
spacings that are critical to map $\approx$ 10′-sized structures. The spectral
structure of the large ($\gtrsim$ 1$\farcm$85) angular-sized sources, namely,
NGC 4789, NGC 4827, NGC 4839, NGC 4869 and 2MASX J13004385$+$2824586 are
elaborated further in the Appendix (Sec. A.1.1).

###  4.2 Radio Morphologies of RPS Galaxies

Table 4: A Summary of Radio Properties of the RPS Galaxies in the Coma Cluster Field Observed Using the uGMRT. Source_ID | Optical Position | Vel. | rms | $S_{\rm 400MHz}$ | $S_{\rm 700MHz}$ |  | $S_{\rm 1.4GHz}^{\amalg}$ | Radio
---|---|---|---|---|---|---|---|---
| R.A. | Decl. |  | B-3 | B-4 |  |  | $\alpha_{\rm 400MHz}^{\rm 700MHz}$ |  | Morphology
| (J2000) |  |  ($\mu$Jy b-1) | (mJy) |  | (mJy) |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) | (11)
(a) GMP 4629ϝ | 12:57:50.27 | 28:10:13.7 | 6918 | 22 | $-$ |  $\lesssim$0.80 |  $\lesssim$0.33Γ | $-$ |  0.03 $\pm$0.01 | $-$
(b) GMP 4570ϝ | 12:57:56.81 | 27:59:30.6 | 4565 | 18 | $-$ |  1.04 $\pm$0.22 |  $\lesssim$0.60Γ |  $\lesssim$ $-$0.98 |  0.55 $\pm$0.06 | T
(c) KUG 1255$+$283† | 12:57:57.75 | 28:03:41.5 | 8136 | 24 | 18 |  17.29 $\pm$0.69 |  13.43 $\pm$0.36 |  $-$0.45 $\pm$0.08 |  6.76 $\pm$0.08 | T
(d) NGC 4848† | 12:58:05.58 | 28:14:33.3 | 7184 | 24 | 24 |  60.66 $\pm$2.12 |  43.41 $\pm$0.80 |  $-$0.60 $\pm$0.07 |  23.85 $\pm$0.11 | T
(e) NGC 4853 | 12:58:35.20 | 27:35:47.1 | 7688 | 24 | 24 |  6.79 $\pm$0.41 |  4.43 $\pm$0.12 |  $-$0.77 $\pm$0.12 |  1.35 $\pm$0.15 | A, T
(f) GMP 4060 | 12:58:42.60 | 27:45:38.0 | 8686 | 22 | 14 |  $\lesssim$0.40 |  $\lesssim$0.31 | $-$ |  $<$0.083 | $-$
(g) NGC 4854 | 12:58:47.44 | 27:40:29.3 | 8383 | 22 | 12 |  $\lesssim$0.52 |  $\lesssim$0.37 | $-$ |  $<$0.098 | $-$
(h) IC 3949† | 12:58:55.95 | 27:50:00.4 | 7526 | 18 | 12 |  7.48 $\pm$0.34 |  5.29 $\pm$0.19 |  $-$0.61 $\pm$0.10 |  2.37 $\pm$0.09 | T
(i) NGC 4858† | 12:59:02.07 | 28:06:56.4 | 9416 | 36 | 12 |  22.11 $\pm$0.68 |  12.13 $\pm$0.48 |  $-$1.07 $\pm$0.10 |  8.73 $\pm$0.13 | T
(j) Mrk 58† | 12:59:05.30 | 27:38:39.9 | 5419 | 24 | 24 |  12.15 $\pm$0.61 |  7.93 $\pm$0.27 |  $-$0.76 $\pm$0.11 |  3.29 $\pm$0.15 | T
(k) KUG 1257$+$278 | 12:59:39.82 | 27:34:35.9 | 5011 | 12 | 18 |  2.28 $\pm$0.21 |  1.41 $\pm$0.19 |  $-$0.86 $\pm$0.29 |  0.51 $\pm$0.07 | T
(l) GMP 3071 | 12:59:56.15 | 27:44:47.3 | 8920 | 22 | 14 |  $\lesssim$0.24 |  $\lesssim$0.11 | $-$ |  0.05 $\pm$0.02 | $-$
(m) GMP3016 | 13:00:01.08 | 28:04:56.2 | 7765 | 22 | 12 |  $\lesssim$0.29 |  $\lesssim$0.23 | $-$ |  $<$0.043 | $-$
(n) GMP 2923 | 13:00:08.07 | 27:46:24.0 | 8672 | 22 | 14 |  $\lesssim$0.30 |  $\lesssim$0.21 | $-$ |  $<$0.034 | $-$
(o) Mrk 60 | 13:00:09.14 | 27:51:59.3 | 5316 | 24 | 12 |  2.29 $\pm$0.52 |  1.36 $\pm$0.18 |  $-$0.93 $\pm$0.46 |  1.12 $\pm$0.03 | A, T
(p) KUG 1258$+$277 | 13:00:29.23 | 27:30:53.7 | 7395 | 22 | 12 |  $\lesssim$0.19 |  $\lesssim$0.12 | $-$ |  $<$0.094 | $-$
(q) KUG 1258$+$279A† | 13:00:33.73 | 27:38:15.6 | 7485 | 24 | 12 |  10.52 $\pm$0.56 |  6.96 $\pm$0.20 |  $-$0.74 $\pm$0.11 |  3.70 $\pm$0.09 | T
(r) IC 4040† | 13:00:37.86 | 28:03:28.7 | 7675 | 24 | 13 |  53.33 $\pm$1.51 |  29.62 $\pm$0.26 |  $-$1.05 $\pm$0.05 |  16.31 $\pm$0.10 | T
(s) NGC 4911† | 13:00:56.06 | 27:47:27.2 | 7985 | 24 | 12 |  50.58 $\pm$0.99 |  29.24 $\pm$0.16 |  $-$0.98 $\pm$0.04 |  15.08 $\pm$0.23 | A
(t) NGC 4921 | 13:01:26.15 | 27:53:09.5 | 5470 | 32 | 12 |  1.89 $\pm$0.48 |  $\lesssim$0.65 |  $\lesssim$ $-$2.05 |  0.44 $\pm$0.05 | A

Eight of our extended radio sources are also galaxies with RPS tails of gas
and embedded young stars. Below, we discuss using our 250–500 MHz and 550–850
MHz bands continuum (with deeper sensitivity) data, the RPS galaxies in the
Coma cluster. Their radio properties, measured from our data along with
measurements at 1.4 GHz (Chen et al., 2020), are listed in Table 4, and Fig. 1
depicts source_IDs (alphabetic characters) and positions (‘$+$’ marks). As
mentioned in Sec. 3, the radio emission associated with the ultra-diffuse
galaxies that is found in our data will be undertaken as a separate study.

RPS galaxies are characterized by gas being stripped, from the affected
galaxy, by the intracluster medium (ICM). This ram pressure, especially at the
early interaction stage with compression of the interstellar medium (ISM), can
trigger star formation. Subsequently, as the cold ISM is depleted, the star
formation is quenched (e.g., Gunn & Gott, 1972; Nulsen, 1982; Koopmann &
Kenney, 2004; Crowl et al., 2005; Boselli et al., 2016). Thus, ram pressure
stripping is an important process affecting galaxy evolution in rich
environments.

In Table 4, we present the radio results for 20 RPS galaxies from Chen et al.
(2020) that are confirmed members of the Coma cluster, ordered in increasing
right ascension. Individual columns depict source_ID, source position,
spectroscopic redshift, rms noises at the 250–500 MHz and 550–850 MHz bands in
the near vicinity of the source, integrated flux densities at the 250–500 MHz
and 550–850 MHz bands, and the spectral index $\alpha$(400–700 MHz) of the
source. The source_IDs of the RPS galaxies (in dark-red ‘$+$’ signs) are
labeled adjacent to their positions in Fig. 1, which are listed in Table 4.

Eight of the 20 RPS galaxies (Chen et al., 2020) are also extended ($\gtrsim$
12.6 kpc) radio sources, and are marked by ‘$\dagger$’ alongside their
source_IDs in Table 3. In addition to the eight RPS galaxies, we detected five
more galaxies in our low radio frequency images (IDs = b, e, a, o, and t; see
Table 4). Figs. 3 and 5 show images of these eight and five (total 13) RPS
galaxies, respectively, detected in our low frequency images. The source_ID as
tabulated in Table 4 is labeled in the lower-right corner of each image in
Figs. 3 and 5. The radio contours, in magenta and blue correspond,
respectively, to the 250–500 MHz and 550–850 MHz band images that are overlaid
on the grayscale SDSS (DR12) $r$-band image. Two sources, GMP 4629 and GMP
4570, i.e., source_IDs (a) and (b) respectively, were not covered in our
550–850 MHz band pointings. Seven RPS galaxies that are not detected in either
of the two bands are GMP 4629, GMP 4060, NGC 4854 (a.k.a. GMP 4017), GMP 3071,
GMP 3016, GMP 2923 and KUG 1258$+$277 (a.k.a. GMP 2640), i.e., source_IDs,
(a), (f), (g), (l), (m), (n), and (p), respectively. Two sources, GMP 4629 and
GMP 3071, from these seven sources, were marginally detected at 1.4 GHz (Chen
et al., 2020), and assuming a spectral index $\alpha$ = $-$0.7 for these two
sources, the non-detections are consistent in our 250–500 MHz and 550–850 MHz
band images within the uncertainties.

Grishin et al. (2021) observed nine low-mass post-starburst galaxies in the
Coma cluster using the multiobject Binospec spectrograph on board the 6.5 m
MMT. They reported that two RPS galaxies (GMP 4060 and GMP 2923) exhibit
spectacular tails of material stripped by the ram pressure of the hot ICM with
H$\alpha$ emission suggesting ongoing star formation, although their disks are
not star forming (see also Venturi et al., 2022). The lack of star formation
in their disks suggests that they could be classified as post-jellyfish
galaxies; similar but typically more massive, jellyfish systems have active
star formation in their disks and tails (Smith et al., 2010; Yagi et al.,
2010). In Appendix (Sec. A.2), we describe the radio morphologies of the
additional five RPS galaxies that are detected in our low radio frequency
images, namely, source_IDs, (b), (e), (k), (o) and (t). We also provide
salient spectral features, using the formulation discussed above, for the
three of these five RPS sources that are detected in both bands of uGMRT in
Sec. 4.2.1 below, and images of the remaining three of five RPS sources in
Fig. 6.

####  4.2.1 Spectral Structure of RPS Galaxies

---
Figure 6: Spectral index images of the remaining three of five RPS galaxies in
the Coma cluster field that are imaged using 250–500 MHz band and 550–850 MHz
band data at matched angular resolutions (= 8′′). The source_ID, as tabulated
in Table 4, is labeled in the lower-right corner of each image. The optical
host positions are marked by a ‘$+$’ sign. The images are displayed in linear
scales and the scale bar depicts the spectral index range. The magenta and
blue radio contours (= five times the local rms noise) are also overlaid,
which correspond to 250–500 MHz (band 3) and 550–850 MHz (band 4) at the
angular resolutions of 6$\farcs$1 and 3$\farcs$7, respectively. See also Fig.
4 for more details.

Our measurements of the integrated spectral index for all RPS galaxies at the
250–500 MHz and 550–850 MHz bands agree, within uncertainties, with
measurements at 1.4 GHz using the VLA (Chen et al., 2020). Fig. 6 shows
spectral index images of three of five RPS galaxies that are detected in both
bands, 250–500 MHz and 550–850 MHz images (in the order presented in Table 4
with the source_ID labeled in the lower-right corner of each image). Similar
to the spectral structure of all tailed radio sources, these remaining sources
also show spectral structures that gradually steepen from the flat spectrum
head with increasing distance from the head along the tail. The spectral
trends of all RPS galaxies are rather similar. Our results hint that the radio
tail has a steeper spectrum than the radio core associated with the host
galaxy (see below for a quantitative analysis).

The majority, 13 out of 20 RPS galaxies, show signatures of ram pressure
stripping, based on our low radio frequency, 250–500 MHz and 550–850 MHz band
images. The presence of radio continuum tails in 13 out of 20 RPS galaxies is
reported for the first time at the 250–500 MHz and 550–850 MHz bands of uGMRT,
which reveal the presence of relativistic electrons and magnetic fields in the
stripped tails. Of these 13, radio continuum tails in three RPS galaxies,
(namely, NGC 4853, IC 3949, and NGC 4911) were not detected by Chen et al.
(2020). However, radio tails in NGC 4853 and IC 3949 were detected by (Roberts
et al., 2021) and we detect these, as well as the new tail for NGC 4911. The
larger extent of the 250–500 MHz band image as compared to the extent of the
550-850 MHz band image along with our spectral index images unambiguously
suggest that the tail has a steeper spectrum than the radio emission
associated with the host galaxy. Furthermore, the spectral index between
250–500 MHz and 550–850 MHz shows hints of spectral steepening as a function
of distance from the head to the tail. This is typical of head-tail radio
sources, suggesting ageing of synchrotron electrons (Lal & Rao, 2004). Chen et
al. (2020) also detected significant H$\alpha$ or star formation tails in half
of the RPS galaxies. Finally, the radio continuum tails in our observations
for all 13 RPS galaxies are spatially coincident with the H$\alpha$ or star
formation tails, consistent with Bravo-Alfaro et al. (2000) and Chen et al.
(2020).

##  5 Discussion

We have used the deepest radio images of the Coma cluster in the 250-500 MHz
and 550-850 MHz bands to image the tailed cluster radio galaxies and study,
for the first time using a radio-selected sample, the connections between the
orientation and intrinsic properties of the tails and the cluster environment.
With the primary novel goal of studying the interplay of numerous tailed radio
galaxies in the Coma cluster and the merger and accretion history of the Coma
cluster, we have presented high-resolution, high-sensitivity radio
morphologies of 24 extended ($\gtrsim$12.6 kpc) radio sources associated with
Coma cluster galaxies and spectral index distributions for 20 of the 24
extended radio sources using the uGMRT. We have also presented high-
resolution, high-sensitivity radio morphologies for 13 (of 20) detected RPS
galaxies associated with the Coma cluster and spectral index distributions for
11 of the 13 RPS galaxies using the uGMRT. Barring a few sources, e.g., NGC
4827, the surface brightness of almost all extended sources is a maximum at
the location of the optical host and decreases away from the center as
expected for radio sources residing in a cluster environment. Similarly, the
surface brightness of RPS galaxies is also a maximum at the location of the
optical host and decreases away from the center along the tail.

###  5.1 Spectral Properties

---
Figure 7: Distributions of $\alpha$, spectral index between 250–500 MHz and
550–850 MHz (i) for the 20 (of 24) extended radio sources (in red; Column 9 of
Table 3), and 13 (of 20) RPS galaxies (in blue; Column 9 of Table 4), shown in
the upper panel (A), and (ii) for the host galaxy (in red) and radio tails (in
blue) of the 23 (20 extended radio sources including 8 RPS galaxies and
additional 3 RPS galaxies) sources, shown in the lower panel (B). In both
panels, the sources in the left bins, $\alpha$ $\lesssim$ 0.75, are steep
spectrum sources and sources in the right bins, $\alpha$ $\gtrsim$ 0.75 are
flat spectrum sources. Blue arrows denote RPS galaxies that are detected at
250–500 MHz, but undetected at 550–850 MHz. Note that more than half of the
extended radio sources are steep spectrum sources, and a significant number of
RPS galaxies also have steep spectra (see upper panel, A). The tail emission
has steeper spectra than the emission at the location of the host galaxy in a
majority of sources (see lower panel, B).

Fig. 7 (upper panel, A) shows the distributions of $\alpha$, the spectral
index between 250–500 MHz and 550–850 MHz for the 20 (of 24) extended radio
sources (in red; Column 9 of Table 3), and 13 (of 20) RPS galaxies (in blue;
Column 9 of Table 4). A majority of the extended radio sources (55%) and RPS
galaxies (69%) have steep spectra. In addition, the tail region spectra appear
steeper than the cores. Apart from the radiative cooling of relativistic
electrons that produce a break/steepening in the spectrum of particles, the
electrons’ adiabatic losses, and the decrease of the magnetic fields in radio-
emitting plasma that outflows from the cores can further shift the break in
the observed radio spectrum to lower frequencies, contributing to the spectral
steepening.

Fig. 7 (lower panel, B) shows the distributions of $\alpha$, spectral index
between 250–500 MHz and 550–850 MHz for the host galaxy (in red) and radio
tails (in blue) of the 23 sources (20 extended radio sources, which includes
eight RPS galaxies and three additional RPS only galaxies). We determined
emission from the host galaxy (size = D25), and wherever possible, emission
from the tail, whose size is equal to the host galaxy. This suggests that the
radio properties of the host galaxy are in general agreement with those of
star-forming galaxies, with a spectral index $\alpha$ $\approx$ $-$0.7, while
the tail appears significantly different. The tail spectral index is found to
be steeper compared to the host galaxy, reaching a mean spectral index of
$\alpha$ $\approx$ $-$1.4, indicating a significant ageing of electrons and/or
adiabatic expansion through the tail. Although we used only uGMRT data to
derive the spectral results presented in this paper, we note that our
integrated spectra are consistent with earlier work, e.g., RPS galaxies: Chen
et al. (2020) and NGC4869: Lal (2020b). Furthermore, the radio continuum in
RPS galaxies is found to be colocated with H$\alpha$, not only within the host
galaxy, but also within the extended tails in several galaxies (Chen et al.,
2020). Although the nature of the interplay between gas stripping and star
formation activity might vary from galaxy to galaxy depending on their size,
location, and orbit, it seems that gas removal is associated with the
quenching of star formation (see also Boselli, Fossati & Sun, 2021). A
detailed analysis of these properties for these sources, along with fainter
and detected (unresolved and extended) sources, will be undertaken as a
separate project.

###  5.2 Equipartition Parameters and Radiative Ages

Table 5: Radio Luminosity and Equipartition Parameters Along with Radiative Age for 16 Extended Cluster-member Sources, Eight Extended/RPS Sources, and Five RPS galaxies; see also Sect. 5.2. |  | Source_ID | LLS | L400MHz | $B_{\rm min}$ | $U_{\rm min}$ | $P_{\rm min}$ | Age
---|---|---|---|---|---|---|---|---
|  |  | (arcmin) | (erg s-1 Hz-1) | ($\mu$G) | (erg cm-3) (dyne cm-2) | (yr)
|  |  |  | ($\times 10^{20}$) |  | ($\times$ $10^{-13}$) | ($\times$ $10^{-13}$) | ($\times$ $10^{8}$)
(1) | (2) | (3) | (4) | (5) | (6) | (7
1 |  | 2MASX J12520684$+$2701352 | 0$\farcm$45 | 0.4 | 2.4 | 5.8 | 1.9 | 1.7
2 |  | NGC 4789 | 7$\farcm$37 | 28.1 | 2.5 | 5.8 | 1.9 | 1.7
3 |  | Mrk 53 | 1$\farcm$23 | 0.9 | 3.1 | 9.1 | 3.0 | 1.6
4 |  | NGC 4827 | 4$\farcm$66 | 19.7 | 3.0 | 8.7 | 2.9 | 1.6
5 |  | NGC 4839 | 2$\farcm$47 | 27.2 | 3.1 | 9.3 | 3.1 | 1.6
6 |  | Mrk 55 | 0$\farcm$57 | 0.5 | 3.0 | 8.5 | 2.8 | 1.6
| (b) | GMP 4570‡ | 0$\farcm$25 | 0.1 | 2.7 | 7.2 | 2.4 | 1.7
7 | (c) | KUG 1255$+$283† | 0$\farcm$67 | 3.0 | 3.5 | 11.9 | 4.0 | 1.5
8 | (d) | NGC 4848† | 1$\farcm$23 | 7.7 | 3.5 | 11.5 | 3.8 | 1.5
9 |  | 2MASX J12581865$+$2718387 | 0$\farcm$71 | 1.5 | 2.5 | 6.3 | 2.1 | 1.7
| (e) | NGC 4853 | 0$\farcm$26 | 1.0 | 3.4 | 10.9 | 3.6 | 1.5
10 |  | Mrk 56 | 1$\farcm$21 | 1.0 | 2.0 | 4.0 | 1.3 | 1.8
11 |  | Mrk 57 | 0$\farcm$90 | 2.2 | 2.8 | 7.6 | 2.5 | 1.7
12 | (h) | IC 3949† | 0$\farcm$50 | 1.1 | 2.8 | 7.7 | 2.6 | 1.7
13 | (i) | NGC 4858† | 0$\farcm$79 | 2.8 | 3.1 | 9.4 | 3.1 | 1.6
14 | (j) | Mrk 58† | 0$\farcm$74 | 0.9 | 3.0 | 8.6 | 2.9 | 1.6
15 |  | NGC 4869 | 6$\farcm$63 | 165.1 | 2.9 | 8.3 | 2.8 | 1.6
16 |  | NGC 4874 | 0$\farcm$50 | 62.5 | 7.0 | 46.6 | 15.5 | 0.8
| (k) | KUG 1257$+$278 | 0$\farcm$38 | 0.1 | 2.4 | 5.4 | 1.8 | 1.8
17 |  | 2MASX J12594009$+$2837507 | 0$\farcm$72 | 0.3 | 1.3 | 1.6 | 0.5 | 1.7
| (o) | Mrk 60 | 0$\farcm$41 | 0.2 | 2.9 | 8.4 | 2.8 | 1.7
18 |  | 2MASX J13001780$+$2723152 | 1$\farcm$79 | 5.2 | 1.5 | 2.1 | 0.7 | 1.7
19 | (q) | KUG 1258$+$279A† | 1$\farcm$01 | 1.5 | 2.9 | 8.4 | 2.8 | 1.6
20 | (r) | IC 4040† | 2$\farcm$18 | 8.4 | 3.2 | 10.2 | 3.4 | 1.6
21 |  | 2MASX J13004067$+$2831116 | 0$\farcm$96 | 3.7 | 2.8 | 7.8 | 2.6 | 1.6
22 |  | 2MASX J13004385$+$2824586 | 1$\farcm$85 | 3.2 | 3.0 | 8.7 | 2.9 | 1.6
23 | (s) | NGC 4911† | 0$\farcm$73 | 8.2 | 3.0 | 8.7 | 2.9 | 1.6
| (t) | NGC 4921‡ | 0$\farcm$47 | 0.1 | 3.2 | 9.7 | 3.2 | 1.6
24 |  | NGC 4927 | 0$\farcm$66 | 1.5 | 3.5 | 12.0 | 4.0 | 1.5

Due to a lack of polarization information, for both the extended and RPS
galaxies in the Coma cluster, the estimates of the magnetic field are
performed using the minimum energy conditions. We assume (i) a cylindrical or
a spherical geometry for the source, (ii) an electron population radiating at
frequencies from 100 MHz to 10 GHz, (iii) the energy carried by the electrons
is half the total energy of all particles, (iv) the filling factor of the
emitting region is unity, and (v) the angle between the uniform magnetic field
and the line of sight is 90∘ (Miley, 1980). We note that this method
calculates the synchrotron luminosity using a fixed high- and low-frequency
cutoffs, instead, low and high energy cut-offs for the particle distribution
should be used (Brunetti, Setti & Comastri, 1997; Beck & Krause, 2005; van
Weeren et al., 2009, and references therein). Taking the latter into account,
the corrected equipartition parameters do not change significantly.
Furthermore, taking a ratio of 100 instead of 2 for the energy in relativistic
protons to that in electrons results in equipartition magnetic field strengths
about a factor of 3 higher. We measure the integrated flux densities from both
bands, the 250–500 MHz and 550–8500 MHz images, and determine spectral
indices, a simple power law, and estimate the equipartition magnetic field,
the minimum energy density, and the minimum pressure exerted by the
relativistic gas in the radio source. We further assume $\alpha$ = $-$0.7 for
sources that are not detected in the 550–850 MHz band of uGMRT because the
non-detections are consistent in our 250–500 MHz and 550–850 MHz band images
within the uncertainties.

We also derive the radiative lifetime (Jaffe & Perola, 1973) using

${t}=1590\times\frac{\sqrt{B_{\rm eq}}}{(B_{\rm eq}^{2}+B_{\rm
IC}^{2})}\times\frac{1}{\sqrt{(1+z)~{}\nu_{\rm br}}}~{}{\rm Myr}.$

Here, ${B_{\rm eq}}$ is the equipartition magnetic field (in $\mu$G), ${B_{\rm
IC}}$ is the inverse Compton equivalent magnetic field (= 3.25 (1 + $z)^{2}$
$\mu$G), and the frequency where the radio spectrum changes by 0.5, called the
break frequency, $\nu_{\rm br}$ is expressed in GHz (Miley, 1980). Compared to
earlier studies at high frequencies ($\gtrsim$ 1.4 GHz), here, we reported
three new detections for the RPS galaxies for the first time at the 250–500
MHz and 550–850 MHz bands of uGMRT. We thus believe that $\nu_{\rm br}$ should
be below 1.4 GHz, and therefore, assume $\nu_{\rm br}=$ 0.7 GHz.

---
Figure 8: (Top) NGC 4874 Chandra X-ray image (bin = 1′′, convolved with
$\sigma$ = 3′′ Gaussian) in the 0.5–4.0 keV energy band with uGMRT 1050–1450
MHz band contours (red; 2$\farcs$1 resolution from Lal (2020b)). uGMRT
provides the combination of best sensitivity and higher angular resolution
image (see also Table1). The lowest radio contour plotted is three times the
local rms noise (labeled in the lower-left corner) and subsequent contours
increase by factors of 2. (bottom) SDSS $r$-band image with the same uGMRT
contours as in the top panel. The yellow SDSS $r$-band surface brightness
contour is plotted at 0.1 $\times$ the peak surface brightness (= 8.73 photons
s-1 arcsec-2). The low-frequency radio lobes bend and flare up outside the
X-ray mini-corona, but are completely embedded within the optical host (D25 =
144′′) galaxy (for previous studies of the radio lobes around NGC 4874, see
Sun et al. (2005) and Sanders et al. (2014)). Comparing these higher frequency
radio observations to those in Fig. 3 (250-500 MHz and 550-850 MHz), we note
there is no evidence of additional extended radio structures (e.g. at larger
distances from NGC 4874) that might have arisen from an earlier/older outburst
from the central SMBH.

Table 5 lists the largest linear size of the source at 250–500 MHz (band 3) of
the uGMRT, and these equipartition parameters, namely, monochromatic
luminosity at 400 MHz using 250–500 MHz band data, equipartition magnetic
field, minimum energy density, minimum pressure, and the radiative age. These
radiative age estimates are consistent with the hypothesis that the radio
plasma ages due to synchrotron cooling and inverse Compton losses.

As Table 5 shows, the minimum pressure values for all the cluster-member
galaxies are comparable (a few dyne cm-2), with one exception, NGC 4874 (see
Fig. 8). NGC 4874 is one of the two BCGs at the cluster core (the other being
NGC 4889, not detected in the radio band, see also Fig. 9). The projected
linear extent of NGC 4874 (in the 250–500 MHz band) is 0$\farcm$81 ($\approx$
22.7 kpc) and the spectral index is $-$0.67 $\pm$0.08 (Lal, 2020a), which
suggests that it could be a compact steep spectrum source (see also Fanti et
al., 1990; O’Dea, 1998). Its age (Table 5) is consistent with this
possibility. It hosts a mini-corona of $\sim 1$ keV gas (see Vikhlinin et al.,
2001; Sun et al., 2005; Sanders et al., 2014). Sun et al. (2007) showed that
such systems were quite common around massive galaxies in clusters. For NGC
4874, the radio jet appears to be confined by the 1 keV mini-corona (Sun et
al., 2007; Sanders et al., 2014) and only blossoms into radio lobes after the
jet has transitioned from the corona to the hot (nearly 10 keV) ICM. Indeed,
Fig. 8 shows the prominent wide-angle tail becoming prominent outside the
central corona. With its high pressure environment, at the bottom of the
potential well of Coma, it should not be surprising that the minimum pressure,
derived from the radio, is significantly higher than that of the other
noncentral Coma galaxies.

###  5.3 Orientation of Trailing Features

---
Figure 9: Composite SDSS (DR12) $r$-band image of the Coma cluster with
superposed uGMRT (250–500 MHz band) contours. Two BCGs, NGC 4874 (source_ID
16) and NGC 4889 (marked with ‘$*$’ and is 4$\farcm$58 east of NGC 4874), are
also shown. The positions of the extended radio sources (Table 3) and the RPS
galaxies (Table 4) are marked with magenta ‘$+$’ and blue ‘$+$’, respectively.
The radio contours corresponding to the 250–500 MHz band (displayed in
thumbnail images presented in Figs. 3 and 5) are displayed in logarithmic
scale (= logarithm of 10 times the angular size of the source in arcminutes)
and overlaid on the SDSS (DR12) $r$-band image at their proper position to
emphasize the optical hosts associated with the respective radio galaxies. The
radio contours are color coded accordingly to redshifts, where blue marks the
lowest redshift (= 0.01523) galaxy, red marks the highest redshift (= 0.03707)
galaxy; the intervening galaxies are colored with increasing gradient from
smaller (blue) to higher (red; see also Fig. 2 for the redshift scale bar).
The lowest radio contour is six times the local rms noise, for clarity and
subsequent contours increase by factors of 2. The local rms noise is tabulated
in Tables 3 and 4 for 250–500 MHz (Column 5) of the uGMRT. Seven RPS galaxies
that are neither detected in the 250–500 MHz band nor in the 550–850 MHz band
of uGMRT are marked with boxes (also color coded accordingly to redshifts).
The vectors depict projected motion of these galaxies in the ICM as inferred
from their radio morphologies.

A characteristic trait of an RPS galaxy is the tail of gas trailing behind its
host galaxy, opposite to its direction of motion. The slender curved
morphology suggests an orbit through the cluster, along which a trail of
radio-emitting material that has been left behind. For example, we find an
ensemble of seven sources, namely, KUG 1255$+$283, GMP 4570, NGC 4848, IC
3949, NGC 4858, Mrk 58, and NGC 4869, all within $\sim$14′ ($\approx$ 390 kpc)
of each other, located $\sim$15$\farcm$2 (= 445 kpc) east of NGC 4874, which
seem to be moving into the cluster center, though seen in projection. We
visually estimated the direction of the stripping features of all extended
radio sources and RPS galaxies relative to one of the two core BCGs of the
Coma cluster, NGC 4874. To estimate the projected direction of motion of the
host galaxy, we assume that tails of radio sources are collimated jets as they
trail away from the host galaxy. In our high-resolution, high-sensitivity deep
images, the radio tails have been detected in almost all extended sources and
detected RPS galaxies. It is not, however, possible to produce 3D curvature
because we lack knowledge of both the tangential velocities and the complete
orbits.

---
Figure 10: Histograms showing distributions of redshifts (upper panel) and
orientation of the projected motion of the host galaxy with respect to its
radial vector, $\theta$ (lower panel), in projection. Eight of our extended
radio sources that are also galaxies with RPS tails of gas and embedded young
stars are included in both distributions. The histograms (slightly shifted
with respect to one another for clarity) are for the extended radio sources
(in red) and for RPS galaxies (in blue). The histogram showing the
distribution of all galaxies within the mapped ($\sim$7.5 deg2) area and with
4000 $<$ $cz$ $<$ 9400 km s-1 corresponds to the Y-axis on the right side
(from Huchra et al., 1990). Note that there is weak evidence for more extended
radio sources and RPS galaxies with $cz$ larger than the mean Coma value $\sim
6900\,{\rm km\,s^{-1}}$, which suggests that the extended radio sources and
RPS galaxies samples do not follow the given Huchra et al. (1990)
distribution. The radial vector is the line joining one of the two core BCGs
of the Coma cluster, NGC 4874, with each host galaxy. The position angles of
the projected motions of the host galaxies are shown in Fig. 9. The sources
with large $\theta$ $\gtrsim$ 90∘ are moving toward the cluster center and the
sources with small $\theta$ $\lesssim$ 90∘ are moving away from the cluster
center. There is a clear excess of sources with a large angle with respect to
the radial vector connecting one of the two core BCGs, NGC 4874, to their
position. Hence, there is an excess of infalling galaxies, suggesting first
infall. While not of high significance, the excess is seen for both the RPS
and extended radio source samples.

The spatial orientations of the projected motions, shown as vectors, of the
host galaxies are shown in Fig. 9. These projected motions are consistent with
the spectral index distribution between the 250–500 MHz band and 550–850 MHz
band, i.e., the spectra are flattest toward the optical hosts, in the vicinity
of the radio cores and they gradually steepen along the radio tails. In the
background, we show an SDSS (DR12) $r$-band image of the Coma cluster with
250–500 MHz band contours overlaid (from the thumbnail images presented in
Figs. 3 and 5). Seven RPS galaxies that are undetected at 250–500 MHz and
550–850 MHz with uGMRT are marked with boxes. The subsamples of 24 extended
radio sources (see Table 3) and 20 RPS galaxies (see Table 4) are not
homogeneous, and the sample of Huchra et al. (1990) is apparent magnitude
limited. Here, we are aiming to characterize the morphologies of extended
radio sources and RPS galaxies in light of the recent (ongoing) merger of the
Coma cluster with the NGC 4839 group. Hence, we believe that inhomogeneities
in the subsamples are not an issue, although their small sizes are limiting.

Following the analysis in Roberts & Parker (2020), in Fig. 10, we show the
distributions of the redshifts (upper panel) and the distributions of the
orientation of the projected motion of the host galaxy with respect to its
radial vector, $\theta$ (lower panel). An angle, $\theta$ = 180∘ corresponds
to the host galaxy moving directly toward the cluster center, and an angle
$\theta$ = 0∘ corresponds to the host galaxy moving away from the cluster
center. Note that there is evidence for more extended radio sources and RPS
galaxies with $cz$ larger than the mean Coma value $\sim 6900\,{\rm
km\,s^{-1}}$, even after excluding the 2MASX J13001780$+$2723152 (source_ID
18, $cz$ = 11121 km s-1) extended radio source. The $p$-value of the
Kolmogorov-Smirnov test is 0.0145, which suggests that the extended radio
sources and RPS galaxies samples do not follow the given Huchra et al. (1990)
distribution. Equivalently, there is a suggestion that the mean (= 7367 km s-1
for extended radio sources and 7025 km s-1 for RPS galaxies), as well as the
median (= 7467 km s-1 for extended radio sources and 7526 km s-1 for RPS
galaxies) velocity of sources is higher than the mean velocities of Coma
cluster galaxies. This difference suggests that RPS galaxies and those with
extended radio emission are in the early phases of merging with the Coma
cluster.111We note that all the effects are seen in projection and, hence,
clearer correlations with orientation and velocity will be complicated by
unknown projection effects and the location of galaxies along the line of
sight through the cluster. Furthermore, a majority of galaxies, both extended
radio sources as well as the RPS galaxies, show angles between 90∘ and 180∘,
i.e., preferentially moving toward the cluster center. Given that the
timescales for stripping can be short (see Boselli, Fossati & Sun, 2021, for
review and references therein), especially for galaxies entering the dense
core of the cluster, such skewness can arise naturally if the majority of
objects recognized as RPS galaxies and extended radio sources are infalling
deep into the cluster potential well for the first time. The fact that RPS
galaxies and extended radio sources share the same trend is also suggestive
that stripping makes an impact on the activity of the central radio source.

Our result that a majority of galaxies with tails are moving toward the
cluster center, i.e., the radio trails point away from the cluster center, is
fully consistent with the findings of Smith et al. (2010), Roberts & Parker
(2020) and Roberts et al. (2021). We note that the tail orientations of the
small post-starburst galaxy sample in Grishin et al. (2021) are less clear and
that their selection criteria may favor objects with more tangential orbits.
Roberts & Parker (2020) noted that the motion of the majority of stripping
galaxies was pointing away from the cluster center, i.e., these galaxies are
moving toward the cluster center. Here, note that a majority of our extended
sources and RPS galaxies are within 1.4 deg2, whereas Roberts & Parker (2020)
extend to much larger radii covering $\sim$9 deg2 with the bulk of the
galaxies lying between 1.4 deg2 and $\sim$9 deg2. Thus, not only the galaxies
in the near vicinity of the cluster center, but also galaxies, with tails and
signs of ram pressure stripping, located much farther away, as seen in
projection, all seem to be moving toward the cluster center.

###  5.4 X-Ray Properties

There has been an increasing effort to obtain multiwavelength data for these
extended radio sources and RPS galaxies. Fig. 2 shows the XMM-Newton 0.5–2.5
keV image of the Coma cluster (Lyskova et al., 2019), with positions of the
extended and the RPS galaxies marked with circles and boxes, respectively. The
names of the sources and their positions are color coded accordingly to
redshifts. The X-ray emission from the bright core and extended X-ray emission
from several extended radio sources has been detected (see Fig. 2). Similarly,
the X-ray emission from the core and the tails for the RPS galaxies have been
detected. For example, Sanders et al. (2014) reported a narrow X-ray tail in
Mrk 60 using Chandra (see also Sun et al., 2021).

Barring 2MASX J12520684$+$2701352, Mrk 53, and 2MASX J12594009$+$2837507,
extended radio sources that do not have X-ray data (see Fig. 2), all extended
sources, as well as the RPS galaxies, are detected in the X-ray band. The
radio core and the associated radio jets of the wide-angle-tail radio source
are not covered in the XMM-Newton image, but the extended radio relic source,
1253$+$275 is partly covered in the XMM-Newton image (see Fig. 2). Lal (2020b)
reported in detail, the radio morphology and the hot gas environment of NGC
4869, and below we discuss the interaction of NGC 4789 and NGC 4839 with their
environments.

---
Figure 11: uGMRT low-angular resolution (= 12′′) spectral index image of NGC
4789 (upper panel). The optical host position is marked with a ‘$+$’ sign. The
image is displayed in linear scale (the scale bar depicts the spectral index
range). The black (dashed) and green radio contours (= five times the local
rms noise) are also overlaid, which correspond to 250–500 MHz (band 3) and
550–850 MHz (band 4), respectively. The lower panel shows (over-sampled)
transverse spectral structure, a gradual steepening from southwest to
northeast, across the width of the radio source (along the direction of
motion). The profiles are determined along three slices marked in the upper
panel, at the location of the host galaxy, and 30′′ to the north/upper (marked
‘U’) and 30′′ to the south/lower (marked ‘L’).

####  5.4.1 Interaction of Radio Sources with the Surrounding ICM

Churazov et al. (2021, and references therein) discussed the ongoing merger of
the NGC 4839 group with Coma. They argue that the group has completed its
first passage through the cluster core (see also Burns, 1990; Lyskova et al.,
2019; Zhang et al., 2019). In this model, the Coma core has experienced two
shocks, first through the bow shock driven by NGC 4839 during its first
passage through the cluster, and subsequently, through a secondary shock
associated with the gas settling back to quasi-hydrostatic equilibrium in the
core. The bow shock associated with the first infall of NGC 4839 has detached
from the group and propagated southwest to the (current) location of
1253$+$275, the relic radio. Interior to the secondary shock (a.k.a. mini-
accretion shock), is a more diffuse and extended radio halo. In this context,
we discuss, below, the salient features, i.e., the interplay of the radio
synchrotron emission and its hot gas environment of two (NGC 4789 and the
1253$+$275 relic, and NGC 4839) of the largest, $\gtrsim$ 2$\farcm$5
($\gtrsim$ 70 kpc) radio sources in our sample.

##### NGC 4789 and the 1253$+$275 relic

The upper panel of Fig. 11 shows the uGMRT low-angular resolution (= 12′′)
spectral index image of NGC 4789. The head located close to the optical host
has a flat spectrum between 250–500 MHz and 550–850 MHz. The spectrum between
these two bands gradually steepens with increasing distance from the head
along the two radio jets, typical of head-tail radio galaxies. In addition, we
notice transverse spectral structure, a gradual steepening from southwest to
northeast across the width of the radio tail, close to the head, before the
jets bend toward the northwestern direction, possibly due to the ballistic
motion of the host galaxy through a dynamic ICM. In the lower panel of Fig.
11, we show profiles of the spectral index to quantify the transverse spectral
structure at three locations (marked in the upper panel, Fig. 11), at the
location of the host galaxy, and 30′′ to the north and 30′′ to the south. The
north/upper and the center (via the radio core) profiles are similar within
uncertainties, while the south/lower profile is relatively steeper.

Fig. 12 displays the low-angular resolution (= 45′′) image of the wide-angle
radio source NGC 4789 and the extended radio relic source in the 250–500 MHz
band. We clearly detect the extended source, 1253$+$275 which was otherwise
resolved in our high-angular resolution image. It is not detected in our
550–850 MHz band image, possibly due to (i) the presence of the compact,
bright Coma A source, $\sim$33′ to the north of NGC 4789, (ii) the ($u,v$)
coverage and (iii) the largest linear structure ($\approx$ 17′ at $\sim$5′′
angular resolution) that can be imaged in this band.

---
Figure 12: Low-angular resolution image of NGC 4789 and radio relic,
1253$+$275, at 45′′ (in light red) and 75′′ (in light-blue) in the 250–500 MHz
band of uGMRT; the radio contours are overlaid on the grayscale background-
subtracted, exposure corrected XMM-Newton image (0.5–2.5 keV). The lowest
radio contour is three times the local rms noise (see lower-left corner) and
subsequent contours increase by factors of 3. The compact radio sources marked
with the ‘$+$’ sign (are labeled) were subtracted to determine the integrated
flux density of the radio relic source. Note the extended radio relic source
shows diffuse emission (in 75′′, low-angular resolution image) with a central
ridge, a bridge of emission connected with the narrow-angle-tailed galaxy NGC
4789.

The radio relic source, 1253$+$275, plausibly associated with the runaway
merger shock (see also Zhang et al., 2019) has a large extent $\approx$ 32′
$\times$ 10′ ($\simeq$ 1.08 $\times$ 0.34 Mpc2), which is broadly consistent
with Giovannini, Feretti & Stanghellini (1991) (see also Bonafede et al.,
2021, 2022, Figs. 1 and 4, respectively). The sharpness of the surface
brightness contours suggests that the relic consists of a high-surface-
brightness southwestern part and a fainter, diffuse low-surface-brightness
northwestern part. Although in the XMM-Newton X-ray image (Fig. 12) a shock is
not readily seen, the presence of a discontinuity in X-ray and Sunyaev-
Zel’dovich data at the location of the radio relic source is confirmed by
several studies (see, e.g. Simionescu et al., 2013; Basu et al., 2016). The
radio relic is located at the cluster periphery, $\sim$70′ ($\simeq$ 2 Mpc)
from the Coma cluster center, in the habitable zone of runaway shocks, in the
southwest direction, consistent with the predictions of Zhang et al. (2019)
(see also Lyskova et al., 2019; Churazov et al., 2021, for more detailed
discussions of the relic as originating from a runaway shock). Its flux
density in the 250–500 MHz band is $S_{\rm 400\,MHz}$ = 0.98 $\pm$0.06 Jy, not
including contributions from NGC 4789, 5C 4.24, 5C 4.29, 5C 4.31, and FS1
radio sources. Our measurement for the radio relic source is consistent with
the fairly straight spectrum, $\alpha$ = $-$1.18 $\pm$0.06 found by
Giovannini, Feretti & Stanghellini (1991) using WSRT 326 and 608 MHz data.

---
Figure 13: (Top) The uGMRT 250–500 MHz (15′′ resolution) image of NGC 4839
with radio contours (starting at three times the local rms noise; labeled in
the lower-left corner; and increasing by factors of 2). (bottom) The 0.5–2.5
keV background-subtracted, exposure corrected XMM-Newton image with the same
uGMRT contours as in the top panel. Note the tail-like X-ray emission (in
light green), whose spectrum is well described by thermal plasma with the
temperature $\sim 2-4$ keV (e.g. Lyskova et al., 2019) is co-spatial with the
radio tail. This suggests that both thermal and nonthermal plasmas are
affected by the same velocity field. The detailed surface brightness of the
radio tail appears to match that in the X-ray, e.g., a spine of emission
extends along the southeast side of the tail. Spectral steepening can be seen
in the spectral index map (Fig. 4) between the pair of compact inner lobes
(top panel red) and the more extended (light green) outer radio structures.

The tailed radio source to the southwest of the relic is associated with NGC
4789, seen clearly in our high-resolution images (Fig. 3 and see also Fig.
11). The extended radio relic shows diffuse emission with a central ridge, a
bridge of emission connected to the narrow-angle tailed galaxy NGC 4789 (see
Fig. 12), which suggests that this tailed radio galaxy could be the source of
the seed particles feeding the radio relic, 1253$+$275, providing a direct
connection between a radio relic source and the radio galaxy, NGC 4789
(Giovannini, Feretti & Stanghellini, 1991; van Weeren et al., 2017; Bonafede
et al., 2021, 2022).

##### NGC 4839

Fig. 13 displays the 0.5–2.5 keV XMM-Newton image with 15′′ resolution radio
contours overlaid. We see indications of a bow shock and of ram pressure
stripping around NGC 4839 in both radio and X-ray data. The hot sheath, seen
in the X-ray data surrounds the optical host NGC 4839 and coincides with the
low-surface brightness diffuse radio emission. We also note the tail-like
X-ray structure, $\simeq$ 2.5′ ($\sim 70$ kpc), pointing away from the Coma
cluster core. Co-spatial with the X-ray tail is radio emission whose detailed
surface brightness appears to match that in the X-ray, e.g., a spine of
emission extending along the southeast side of the tail. Integrating the band
3 and band 4 emission over the region, which is at least five times the beam
size, and above their 3 $\times$ rms contour to reduce statistical errors, in
the tail, we derive a spectral index $-$1.72 $\pm 0.31$, significantly steeper
than that of the inner radio lobes (see the spectral index map of NGC 4839 in
Fig. 4). The X-ray emission, corresponding to the NGC 4839 group, seems
somewhat disconnected from the diffuse, extended X-ray emission from the Coma
cluster. The two-sided radio jet with slight distortions emerging in P.A.
$\approx$0∘, with a bow-shock-like feature with indications of ram pressure
stripping (see also Fig. 3) was used to suggest that the NGC 4839 group was on
its initial infall into the Coma cluster (Neumann et al., 2001). However,
subsequent analysis showed that the detailed X-ray morphology of the tail
(Fig. 13), and the location of the radio relic were best explained as arising
from a slingshot effect, as NGC 4839, initially infalling into Coma from the
northeast, slows and crosses the apocenter, and reverses its radial velocity
(see Lyskova et al., 2019; Sheardown et al., 2019; Zhang et al., 2019).

##  6 Conclusions

A study of a rich and nearby cluster like Coma can establish a local reference
for studies of clusters at higher redshifts. Hence, we obtained new high-
resolution, high-sensitivity, deep uGMRT images of a $\sim 7.5$ deg2 region
centered on the Coma cluster in two bands, 250–500 MHz band and 550–850 MHz,
with angular resolutions of $\sim$6$\farcs$1 and $\sim$3$\farcs$7, and rms
noise levels of 21.1–-36.6 $\mu$Jy and 12.8–-42.4 $\mu$Jy, respectively. We
detected 135 sources in the 250–500 MHz band that have clear extensions
(minimum size of $0\farcm 45$, 12.6 kpc at the distance of the Coma cluster)
with peak-to-local-noise ratio $>4$. We culled a complete sample of 24 radio
sources that are associated with the Coma cluster galaxies, whose radial
velocities are in the range 4000 to 9400 km s-1. We also supplement this
radio-selected sample with 20 RPS galaxies from (Chen et al., 2020), of which
eight are included in the extended radio source sample and an additional five
are detected and extended (but with either peak-to-local-noise ratio $<4$ or
extent $<0\farcm 45$).

We presented radio morphologies, radio spectra (from 250-–500 MHz and 550–850
MHz), spectral maps, and equipartition properties for these two, extended
radio source and RPS galaxy, samples. Our results are summarized as follows:

  * (i)

Radio continuum tails, as expected from the effects of ram pressure, are found
in almost all the sources (19 of 24 extended radio sources and nine of 13
detected RPS galaxies) in both bands.

  * (ii)

The radio extent at two bands of the radio continuum tails is consistent with
the length being limited by synchrotron cooling time.

  * (iii)

The derived spectral structure in all tailed radio sources suggests that the
radio spectra steepen from the heads to the outer parts of the tails, as is
typically seen in tailed radio sources.

  * (iv)

The majority of extended radio sources (55%) and RPS galaxies (69%) are steep
spectrum sources. In addition to radiative (synchrotron and inverse Compton)
cooling, these sources may also undergo adiabatic cooling and the decrease of
the magnetic fields in radio-emitting plasma that outflows from the cores can
further shift the break in the observed radio spectrum to lower frequencies,
contributing to the spectrum steepening.

  * (v)

The equipartition properties lie within a narrow range (e.g., $P_{\rm min}$ =
1–3 dynes cm-2), with the exception of NGC 4874, one of the two core BCGs,
whose central energy density and pressure are about five times higher than all
the other Coma-member galaxies, and whose radio source age is about 50% that
of the other Coma galaxies. It is plausible that selection effects may be
responsible for the narrow range.

  * (vi)

The radio jet of NGC 4874 appears to be confined by the 1 keV mini-corona, and
they blossom into radio lobes after the jet has transitioned from the corona
to the hot ICM (see also Sun et al., 2007; Sanders et al., 2014). A comparison
of the lower and higher radio frequency observations shows no evidence, at
lower frequencies, for a population of relativistic particles from any earlier
(older) ourbursts from the central SMBH. In addition, the NGC 4874 radio
source is relatively young - its age is at least $\sim 2$ times smaller than
all the other extended sources (see Table 5). The activity of the central AGN
in the radio band can be viewed as one of the arguments in favor of NGC 4874,
rather than NGC 4889, being the true center of the Coma cluster potential well
in the near past.

  * (vii)

We find an ensemble of seven sources, within $\sim$14′ ($\approx$ 390 kpc),
located $\sim$ 15$\farcm$2 (= 445 kpc) east of the cluster center, and all
moving toward the cluster center, though seen in projection.

  * (viii)

We show that in both the extended radio source sample and the RPS galaxy
sample, the radio morphologies and their spectra suggest that these galaxies
are moving radially toward the cluster center, in agreement with Smith et al.
(2010), Roberts & Parker (2020) and Roberts et al. (2021) who used differently
selected samples. This implies that these galaxies are (predominantly) recent
newcomers to Coma and are infalling into Coma for the first time. We emphasize
that this refers to objects located in the Coma core (at least in projection).

  * (ix)

We find a suggestion that the mean recession velocity of sources moving
radially toward the cluster center is higher than the mean velocity of Coma
cluster galaxies. Coupled with the argument that tailed sources in the core
are on their first infall, this suggests that most of them are infalling from
the near side of the Coma cluster.

  * (x)

The diffuse tail of emission trailing the tailed radio galaxy associated with
NGC 4789 is detected in both uGMRT bands. Moreover, we report transverse
spectral structure, a gradual steepening from southwest to northeast across
the width of the radio source.

  * (xi)

The radio relic, B1253$+$275, plausibly associated with a runaway merger shock
(see also Zhang et al., 2019) has a large extent $\approx$ 32′ $\times$ 10′
($\simeq$ 1.08 $\times$ 0.34 Mpc2) and the low-frequency flux density $S_{\rm
400\,MHz}$ = 0.98 $\pm$0.06 Jy. This extended radio relic shows diffuse
emission with a central ridge, a bridge of emission connected with the narrow-
angle-tailed galaxy NGC 4789, which suggests that this tailed radio galaxy
could be the source of the seed particles feeding the radio relic, 1253$+$275
(see also Giovannini, Feretti & Stanghellini, 1991; Bonafede et al., 2021,
2022).

  * (xii)

The uGMRT observations show a long, broad tail of radio emission ($\simeq$
2.5′ = 70 kpc; see Fig. 13) co-spatial with the X-ray slingshot tail of the
wide-angle radio galaxy NGC 4839. The X-ray and radio tails extend to the
southwest, away from the Coma core. The detailed surface brightness of the
radio tail appears to match that in the X-ray, e.g., a spine of emission
extends along the southeast side of the tail. Spectral steepening between the
compact inner lobes and the outer tailed radio structures is observed.

## Acknowledgments

We thank the anonymous referee for his/her comments that improved this paper.
D.V.L. acknowledges the support of the Department of Atomic Energy, Government
of India, under project no. 12-R&D-TFR-5.02-0700. W.F. and C.J. acknowledge
support from the Smithsonian Institution, the Chandra High Resolution Camera
Project through NASA contract NAS8-03060, and NASA Grants 80NSSC19K0116,
GO1-22132X, and GO9-20109X. N.L. acknowledges partial support by the RSF grant
19-12-00369. R.J.vW. and I.D.R. acknowledge support from the ERC Starting
Grant ClusterWeb 804208 We thank the staff of the GMRT who made these
observations possible. The GMRT is run by the National Centre for Radio
Astrophysics of the Tata Institute of Fundamental Research. This research has
made use of the NED, which is operated by the Jet Propulsion Laboratory,
Caltech, under contract with the NASA, and NASA’s Astrophysics Data System.
This research has made use of the NASA/IPAC Infrared Science Archive, which is
funded by the NASA and operated by the California Institute of Technology.
This research has made extensive use of SAOImage DS9, in addition to software
provided by the CXC in the application packages CIAO.

Facilities: GMRT, Chandra, Sloan Digital Sky Survey

Software: AIPS (van Moorsel, Kemball & Greisen, 1996), CASA (McMullin et al.,
2007), DS9 (Joye & Mandel, 2003), Astropy (Robitaille et al., 2013)

##  Appendix A Extended Radio Sources and RPS Galaxies

In Tables 3 and 4, we list 24 extended ($\gtrsim$12.6 kpc) radio sources and
20 RPS galaxies, respectively, that are confirmed members of the Coma cluster,
ordered in increasing right ascension. The radio images of these extended
cluster-member radio sources and RPS galaxies are presented in Figs. 3 and 5,
in the order listed in Tables 3 and 4, respectively. The radio contours, in
magenta and blue, correspond, respectively, to the 250–500 MHz and the 550–850
MHz band images that are overlaid on the grayscale SDSS (DR12) $r$-band image.

###  A.1 Notes on the Radio Morphology of Individual Extended Sources

Descriptions of the radio morphologies and their optical properties of these
extended sources along with notes from the literature are given below.

##### 1: 2MASX J12520684$+$2701352

(a.k.a. KUG 1249$+$272B) An emission-line galaxy (Kent & Gunn, 1982). The
radio morphologies in the 250–500 MHz and the 550–850 MHz bands are amorphous.
The low-frequency, 250–500 MHz image has larger extent as compared to the
550–850 MHz image, probably due to synchrotron cooling. The largest projected
linear extent of the source in the 250–500 MHz band is 0$\farcm$45 ($\approx$
12.6 kpc). The integrated spectral index is very steep, $\alpha$(400–700 MHz)
= $-$1.23 $\pm$0.13.

##### 2: NGC 4789

The optical host is type SA0 (Kent & Gunn, 1982). The radio morphologies at
both bands show the source to be a narrow-angle-tailed radio galaxy. We barely
detect the extended source, 1253$+$275 in our high angular resolution image
(see Fig. 1). Instead, the tailed radio source at the southwest is seen
clearly in our low-resolution image (Fig. 12). The largest projected linear
extent of the NGC 4789 galaxy in the 250–500 MHz band image (Fig. 3) is
7$\farcm$37 ($\approx$ 206.5 kpc). The host galaxy (D25 = 114$\farcs$3) and
the tail have spectral index, $\alpha$(400–700 MHz), $-$0.46 $\pm$0.02 and
$-$0.51 $\pm$0.03, respectively. The integrated spectral index is flat,
$\alpha$(400–700 MHz) = $-$0.49 $\pm$0.02.

##### 3: Mrk 53

(a.k.a. KUG 1253$+$279) The optical host is Sa with a bright knot to the south
(Kent & Gunn, 1982). The radio emission at both 250–500 MHz and 550–850 MHz
bands is one-sided showing asymmetric tails toward the northwest, extending
beyond the optical host galaxy. The largest projected linear extent of the
source in the 250–500 MHz band is 1$\farcm$23 ($\approx$ 34.5 kpc). The host
galaxy (D25 = 19$\farcs$0) and the tail have spectral index, $\alpha$(400–700
MHz), $-$0.64 $\pm$0.03 and $-$0.43 $\pm$0.04, respectively. The integrated
spectral index is flat, $\alpha$(400–700 MHz) = $-$0.75 $\pm$0.07.

##### 4: NGC 4827

The optical host is S0 and is a low-ionization nuclear emission-line region
galaxy (Kent & Gunn, 1982). The radio morphology at both bands, 250–500 MHz
and 550–850 MHz, is nearly identical. The north and south radio lobes show a
disturbed morphology, extending toward the east, suggesting that the motion of
the host galaxy in the ICM is possibly responsible for these extensions.
Furthermore, the northern jet is of smaller extent than the southern radio
jet, suggesting that projection effects are also at play. The largest
projected linear extent of the source in the 250–500 MHz band is 4$\farcm$66
($\approx$ 130.6 kpc). The host galaxy (D25 = 86$\farcs$7) and the mean of the
northern and southern tails (or radio lobes) have spectral index,
$\alpha$(400–700 MHz), $-$0.11 $\pm$0.01 and $-$0.39 $\pm$0.02, respectively.
The integrated spectral index is flat, $\alpha$(400–700 MHz) = $-$0.49
$\pm$0.01.

##### 5: NGC 4839

The optical host is an SA0, a low/average surface brightness disk-dominated
galaxy (Oemler, 1976), and is the BCG of the NGC 4839 group (Kent & Gunn,
1982). It lies in the cluster outskirts ($\sim$1 Mpc in projection) southwest
of the cluster center. X-ray observations of the Coma cluster have revealed a
wealth of substructures and one of the most prominent is the infalling group
of galaxies associated with the galaxy NGC 4839. The associated radio source
has a wide-angle tailed morphology, i.e., the two-sided radio jet with slight
distortions emerging in P.A. $\approx$0∘ with a bow-shock-like feature with
indications of ram pressure stripping, which suggests that the NGC 4839 group
is falling into the Coma cluster (Neumann et al., 2001). The high-resolution
image, along with the low-angular resolution image of the source in the
250–500 MHz band (see Fig. 13), suggests there are two finger-like features
emanating toward the southwest. These images also suggest that there is low-
surface brightness diffuse radio emission toward the west, which trails behind
the wide-angle-tailed radio galaxy. The largest projected linear extent of the
source in the 250–500 MHz band is 2$\farcm$47 ($\approx$ 69.2 kpc).

##### 6: Mrk 55

(a.k.a. KUG 1254$+$276) The optical host is Sa with no signs of interaction
and is classified as a star-forming galaxy showing signatures of low-
ionization nuclear emission-line region galaxy (Kent & Gunn, 1982; Miller &
Owen, 2002). The radio morphology shows emission associated with the optical
host and two additional knot-like (lobes) emission aligned along the east-
west. There is also very low-surface brightness diffuse radio emission
detected at 250–500 MHz. Although the radio morphology at the 550–850 MHz band
is identical to the 250–500 MHz band, it has smaller extent with no extended
very low-surface brightness diffuse radio emission. The largest projected
linear extent of the source in the 250–500 MHz band is 0$\farcm$57 ($\approx$
16.0 kpc).

##### 7 (c): KUG 1255$+$283

(a.k.a. (GMP 4555, MCG $+$05$-$31$-$035) The elliptical optical host is Sb and
there are possibly two overlapping galaxies with their nuclei $\sim$3′′ apart
(Bothun & Dressler, 1986). The radio emission at both bands, 250–500 MHz and
550–850 MHz, is one-sided, showing asymmetric tails toward the west, extending
$\sim$19.9 kpc beyond the optical host galaxy. The radio extent in the 550–850
MHz band image is smaller than in the 250–500 MHz band image. The source is
also classified as an RPS galaxy (Chen et al., 2020, see Sec. 4). The largest
projected linear extent of the source in the 250–500 MHz is 0$\farcm$67
($\approx$ 18.8 kpc). The source has a flat integrated spectral index,
$\alpha$(400–700 MHz) = $-$0.45 $\pm$0.08, which is consistent with $S_{\rm
1.4GHz}$ = 6.76 $\pm$0.08 mJy, within uncertainties (Chen et al., 2020).

##### 8 (d): NGC 4848

The optical host is a blue disk Scd that shows perturbed gas distributions
with most of the neutral hydrogen in the north and a high H I gas deficiency
(Gavazzi, 1989). The radio emission at both bands, 250–500 MHz and 550–850
MHz, is one-sided with asymmetric tails toward the northwest, extending beyond
the optical host galaxy. The 550–850 MHz image shows smaller extent than the
250–500 MHz image. The source is classified as an AGN (Kent & Gunn, 1982), and
is listed as a RPS galaxy by Chen et al. (2020, see Sec. 4). The largest
projected linear extent of the source at 250–500 MHz band is 1$\farcm$23
($\approx$ 34.5 kpc). The integrated spectral index is $\alpha$(400–700 MHz) =
$-$0.60 $\pm$0.07, which agrees with $S_{\rm 1.4GHz}$ = 23.85 $\pm$0.11 mJy,
within uncertainties (Chen et al., 2020).

##### 9: 2MASX J12581865$+$2718387

(a.k.a. KUG 1255$+$275) The optical host is an irregular galaxy showing
emission lines. More specifically, it is a H I rich galaxy with regular gas
distribution (Kent & Gunn, 1982; Gavazzi, 1989). The radio emission at both
bands, 250–500 MHz and 550–850 MHz, is one-sided, showing asymmetric tails
toward the southeast, extending beyond the optical host galaxy with the
550–850 MHz image showing smaller extent than the 250–500 MHz image. The
largest projected linear extent of the source in the 250–500 MHz band is
0$\farcm$71 ($\approx$ 19.9 kpc). The integrated spectral index is very flat,
$\alpha$(400–700 MHz) = $-$0.22 $\pm$0.10.

##### 10: Mrk 56

(KUG 1256$+$275) The optical host is an S0 with emission-lines (Mazzarella &
Balzano, 1986). The radio emission at both bands, 250–500 MHz and 550–850 MHz,
is one-sided showing asymmetric tails towards the northwest, extending beyond
the optical host galaxy. The 550–850 MHz image shows a smaller extent than the
250–500 MHz image. The largest projected linear extent of the source in the
250–500 MHz band is 1$\farcm$21 ($\approx$ 33.9 kpc). The integrated spectral
index is very flat, $\alpha$(400–700 MHz) = $-$0.11 $\pm$0.08.

##### 11: Mrk 57

The optical host is an irregular H II galaxy with emission-lines (Kent & Gunn,
1982). It is H I rich with a H I distribution displaying an extension to the
north-south (Bravo-Alfaro et al., 2000). The radio emission at both bands,
250–500 MHz and 550–850 MHz, is one-sided, showing asymmetric tails toward the
south, extending beyond the optical host galaxy with the 550–850 MHz image
showing smaller extent than the 250–500 MHz image. The largest projected
linear extent of the source in the 250–500 MHz band is 0$\farcm$90 ($\approx$
25.2 kpc). The host galaxy (D25 = 29$\farcs$25) and the tail have a spectral
index, $\alpha$(400–700 MHz), $-$0.57 $\pm$0.03 and $-$1.12 $\pm$0.05,
respectively.

##### 12 (h): IC 3949

(a.k.a. KUG 1256$+$281) The optical host is SA0, an edge-on spiral galaxy and
the radio emission is dominated by star formation in its disk with a more
quiescent central bulge (Bothun & Dressler, 1986). The source is classified as
an AGN by Kent & Gunn (1982) and it is also classified as the RPS galaxy (Chen
et al., 2020, see Sec. 4). The radio emission at both 250–500 MHz and 550–850
MHz is one-sided. Only the 250–500 MHz image shows asymmetric tails toward the
southwest, extending slightly beyond the optical host galaxy, whereas the
550–850 MHz image has smaller extent and is coincident with the extent of the
optical host. The largest projected linear extent of the source in the 250–500
MHz is 0$\farcm$50 ($\approx$ 14.0 kpc). The integrated spectral index is
$\alpha$(400–700 MHz) = $-$0.61 $\pm$0.10, and agrees with $S_{\rm 1.4GHz}$ =
2.37 $\pm$0.09 mJy, within uncertainties (Chen et al., 2020).

##### 13 (i): NGC 4858

The optical host is an Sb showing interaction with NGC 4860 (at $z$ =
0.02645), which is located to the northeast (Bothun & Dressler, 1986). The
radio emission at both bands, 250–500 MHz and 550–850 MHz, is one-sided,
showing asymmetric tails toward the northwest, extending beyond the optical
host galaxy with the 550–850 MHz image showing smaller extent than the 250–500
MHz image. The source is also classified as the RPS galaxy (Chen et al., 2020,
see Sec. 4). The largest projected linear extent of the source in the 250–500
MHz band is 0$\farcm$79 ($\approx$ 22.1 kpc). The integrated spectral index is
steep, $\alpha$(400–700 MHz) = $-$1.07 $\pm$0.10, and it agrees with $S_{\rm
1.4GHz}$ = 8.73 $\pm$0.13 mJy, within uncertainties (Chen et al., 2020).

##### 14 (j): Mrk 58

(a.k.a. KUG 1256$+$279) The optical host is a blue disk Sa galaxy (Kent &
Gunn, 1982). It shows a very asymmetric gas distribution; most of the H I gas
is lies to the west side, while the east appears depleted (Mazzarella &
Balzano, 1986). The radio emission at both bands, 250–500 MHz and 550–850 MHz,
is one-sided showing asymmetric tails toward the southwest, extending beyond
the optical host galaxy with the 550–850 MHz image showing smaller extent than
250–500 MHz image. The source is also classified as RPS galaxy (Chen et al.,
2020, see Sec. 4). The largest projected linear extent of the source in the
250–500 MHz band is 0$\farcm$74 ($\approx$ 20.7 kpc). The integrated spectral
index is $\alpha$(400–700 MHz) = $-$0.76 $\pm$0.11, and it agrees with $S_{\rm
1.4GHz}$ = 3.29 $\pm$0.15 mJy, within uncertainties (Chen et al., 2020).

##### 15: NGC 4869

A narrow-angle-tailed radio galaxy is hosted by an elliptical galaxy (Venturi,
Giovannini & Feretti, 1990). The radio morphology at both bands 250–500 MHz
and 550–850 MHz, is typical of a head-tail radio source with a weak unresolved
radio core, two oppositely directed radio jets, and a long-low-surface
brightness tail, pointing away from the cluster center. The radio tail has a
conical shape, which initially expands and then recollimates. The radio jet at
$\sim$3$\farcm$5 ($\approx$ 96.1 kpc) bends by $\sim$70 deg with respect to
the initial direction of propagation, after the two radio jets have undergone
a twist and wrap of the two tails. A detailed study of the radio source is
presented in Lal (2020b); Feretti et al. (1990). The largest projected linear
extent of the source in the 250–500 MHz band is 6$\farcm$63 ($\approx$ 185.8
kpc). The host galaxy (D25 = 51$\farcs$24) and the tail have spectral index,
$\alpha$(400–700 MHz), $-$0.62 $\pm$0.01 and $-$1.70 $\pm$0.02, respectively.
The integrated spectral index is steep, $\alpha$(400–700 MHz) = $-$1.12
$\pm$0.01.

##### 16: NGC 4874

One of the two dominant BCGs of the Coma cluster (Baier, Fritze & Tiersch,
1990) is a low-ionization nuclear emission-line region galaxy (Kent & Gunn,
1982). The optical host is a regular low brightness elliptical galaxy (Capetti
et al., 2000). Unlike many relaxed clusters that host a single BCG, Coma has
two very bright galaxies in the core - NGC 4889 and NGC 4874. While the former
is brighter by $\sim 0.5$ magnitude, the latter is rounder and possesses a
rich system of satellite galaxies. NGC 4874 is also a prominent radio galaxy,
which is yet another characteristic feature of giant ellipticals residing at
the bottom of cluster potential wells (Burns, 1990). The source is located
close to the peak of the distributions of galaxies and X-ray gas. The radio
source has a wide-angle tail (WAT) radio morphology and its projected maximum
angular extension is $\sim$30 arcsec, corresponding to $\sim$15 kpc. We detect
the radio core and two radio jets forming a wide angle between them in both of
our 250–500 MHz and 550–850 MHz band images. The largest projected linear
extent of the source in the 250–500 MHz band is 0$\farcm$81 ($\approx$ 22.7
kpc).

This one of two core BCGs of the Coma cluster, NGC 4874 also retains its
central X-ray gas corona, i.e., the interstellar gas with a temperature of 1–2
keV is confined by the hot intergalactic medium of the Coma Cluster into a
compact ($\simeq$ 3 kpc) cloud. The radio jets are found to be anti-correlated
with the X-ray emission, and there are also small X-ray indentations of the
nucleus, where the jets leave the coronal gas (see also Section 5). It seems
that the supermassive black hole in NGC 4874 is depositing its energy outside
of the corona, and it may be ineffective in preventing the cooling taking
place (Vikhlinin et al., 2001; Sanders et al., 2014).

##### 17: 2MASX J12594009$+$2837507

(a.k.a. KUG 1257$+$288B) The optical host is Sc type (Kent & Gunn, 1982). The
250–500 MHz band image suggests that the source has a wide-angle tail
morphology, whose radio emission extends much beyond the extent of the host
galaxy. The largest projected linear extent of the source in the 250–500 MHz
band is 0$\farcm$72 ($\approx$ 20.2 kpc). The source was not covered in the
550–850 MHz band pointings.

##### 18: 2MASX J13001780$+$2723152

(a.k.a. KUG 1257$+$276) The optical host is an irregular face-on spiral galaxy
(Kent & Gunn, 1982). The 250–500 MHz band image suggests that the radio source
emerges from the host galaxy and has two radio lobes, one just northeast of
the radio core and the other east. Both radio lobes have similar surface
brightnesses, and the radio core is offset from the two symmetrical radio
lobes. The largest projected linear extent of the source in the 250–500 MHz
band is 1$\farcm$79 ($\approx$ 50.2 kpc). The source was not covered in the
550–850 MHz band pointings.

##### 19 (q): KUG 1258$+$279A

The optical host shows emission lines of Sa type and is an asymmetrical blue
disk galaxy possibly due to the presence of dust (Bothun & Dressler, 1986).
The radio emission at both bands, 250–500 MHz and 550–850 MHz, is one-sided
showing asymmetric tails to the southeast, extending beyond the optical host
galaxy with the 550–850 MHz band image showing smaller extent than the 250–500
MHz band image. The source is also classified as an RPS galaxy (Chen et al.,
2020, see Sec. 4). The largest projected linear extent of the source in the
250–500 MHz band is 1$\farcm$01 ($\approx$ 28.3 kpc). The host galaxy (D25 =
39$\farcs$24) and the tail have spectral index, $\alpha$(400–700 MHz), $-$0.39
$\pm$0.07 and $-$0.56 $\pm$0.12, respectively. The integrated spectral index
is $\alpha$(400–700 MHz) = $-$0.74 $\pm$0.11, and it agrees with $S_{\rm
1.4GHz}$ = 3.70 $\pm$0.09 mJy, within uncertainties (Chen et al., 2020).

##### 20 (r): IC 4040

(a.k.a. GMP 2559, KUG 1258$+$283, CGCG 160$-$252) The optical host shows
emission lines hosted by a galaxy of spiral or irregular morphological type
(Kent & Gunn, 1982). The radio emission at both bands, 250–500 MHz and 550–850
MHz, is one-sided showing asymmetric tails toward the southeast, extending
beyond the optical host galaxy, with the 550–850 MHz band image showing
smaller extent than the 250–500 MHz band image. The source is also classified
as an RPS galaxy (Chen et al., 2020, see Sec. 4). The largest projected linear
extent of the source in the 250–500 MHz band is 2$\farcm$18 ($\approx$ 61.1
kpc). The integrated spectral index is steep, $\alpha$(400–700 MHz) = $-$1.05
$\pm$0.05, and it agrees with $S_{\rm 1.4GHz}$ = 16.31 $\pm$0.10 mJy, within
uncertainties (Chen et al., 2020).

##### 21: 2MASX J13004067$+$2831116

(a.k.a. KUG 1258$+$287) The optical host is an edge-on spiral galaxy (Kent &
Gunn, 1982). The 250–500 MHz band image suggests that the source has tailed
morphology, whose radio emission extends much beyond the extent of the host
galaxy. The largest projected linear extent of the source in the 250–500 MHz
band is 0$\farcm$96 ($\approx$ 26.9 kpc). The source was not covered in the
550–850 MHz band pointings.

##### 22: 2MASX J13004385$+$2824586

The optical host is an elliptical galaxy (Kent & Gunn, 1982). The radio
morphology in both bands, 250–500 MHz and 550–850 MHz, is nearly identical.
The two jets traveling toward north and south show knotty features. In
addition, the north and south radio lobes show disturbed morphologies, which
are bent toward the east, suggesting that the motion of the host galaxy in the
ICM is possibly responsible for these extensions. Furthermore, the northern
jet is of larger extent than the southern radio jet, and the southern jet is
also more bent, suggesting that projection effects are likely at play. The
largest projected linear extent of the source in the 250–500 MHz band is
1$\farcm$85 ($\approx$ 51.8 kpc). The host galaxy (D25 = 86$\farcs$7) and the
tail have spectral indices, $\alpha$(400–700 MHz), $-$0.53 $\pm$0.04 and
$-$0.83 $\pm$0.05, respectively. The integrated spectral index is steep,
$\alpha$(400–700 MHz) = $-$1.17 $\pm$0.04.

##### 23 (s): NGC 4911

The optical host is a low-ionization nuclear emission-line region galaxy of Sb
type. It is one of the two giant spirals in the Coma cluster showing a close
interaction with its neighbor DRCG 27$-$62 (Kent & Gunn, 1982; Miller & Owen,
2002). The radio emission at both bands, 250–500 MHz and 550–850 MHz, is
symmetrically surrounding the optical host, and radio emission in both bands
are of identical extent. The source is also classified as an RPS galaxy (Chen
et al., 2020, see Sec. 4). The source is nearly circular in shape, and the
largest projected linear extent of the source in the 250–500 MHz band is
0$\farcm$73 ($\approx$ 20.5 kpc). The integrated spectral index is
$\alpha$(400–700 MHz) = $-$0.98 $\pm$0.04, and it agrees with $S_{\rm 1.4GHz}$
= 15.08 $\pm$0.23 mJy, within uncertainties (Chen et al., 2020).

##### 24: NGC 4927

The optical host is a very bright giant early spiral of type Sb (Kent & Gunn,
1982) and is possibly interacting with its neighbor DRCG 27–62 (Bravo-Alfaro
et al., 2000). The radio morphology shows emission associated with the optical
host and two additional radio lobes along the northwest and southeast
directions. Both radio lobes are of nearly identical surface brightnesses and
are located just outside the optical host galaxy. The northern radio lobe
shows slight extensions of radio emission toward the northeast, suggesting
motion of the optical host with respect to the ICM is at play. The largest
projected linear extent of the source in the 250–500 MHz band is 0$\farcm$66
($\approx$ 18.5 kpc). The source was not covered in the 550–850 MHz band
pointings.

####  A.1.1 Spectral Structure of Extended Sources

The spectral structure of the large ($\gtrsim$ 1$\farcm$85) angular-sized
sources, namely, NGC 4789, NGC 4827, NGC 4839, NGC 4869, and 2MASX
J13004385$+$2824586 are elaborated further.

##### 2: NGC 4789

The spectral structure of the classic wide-angle-tailed radio galaxy NGC 4789
is presented in Fig. 4. The head, located close to the optical host, has a
flat spectrum between 250–500 MHz and 550–850 MHz. The spectrum between these
two bands gradually steepens with increasing distance from the head. In
addition, we notice transverse spectral structure, a gradual steepening from
southwest to northeast across the width of the radio tail, close to the head,
before the jets bend toward the northwestern direction, possibly due to the
ballistic motion of the host galaxy through a dynamic ICM. The faintest, and
presumably oldest, far-end part of the tails have felt large scale motions for
the longest period of time, and hence, in the far-end part of the tails, we do
not see transverse spectral structure. As discussed above, this wide-angle-
tailed radio galaxy is feeding the radio relic source, 1253$+$275\.
Unfortunately, the radio galaxy, Coma A causes uncertainties in the 550–850
MHz image. Thus our dynamic range limited map at 550–850 MHz band does not
allow us to perform spectral imaging of this radio relic source (see also Sec.
5.4.1, ‘NGC 4789 and the 1253$+$275 relic’ for a detailed discussion).

##### 4: NGC 4827

The spectral structure of the classic FR II type radio galaxy, NGC 4827 shows
a flat spectrum radio core and jets, which form relatively steeper spectrum
radio lobes. The spectral information is similar in the two lobes and the
lobes are filled with backflow material, which is older in the center than on
the edges of the radio galaxy. The spectrum steepens from the outer regions
toward the center of the source, and also steepens outwards, perpendicular to
the major axis of the source, similar to the spectral structure of FR II radio
galaxies. The radio lobes are not symmetric across the radio jet axis, i.e.,
the eastern extent is larger than the western extent, which is possibly due to
the motion of the host galaxy. In the host galaxy (D25 = 86$\farcs$7), the
northern and southern tails have spectral indices, $\alpha$(400–700 MHz),
$-$0.11 $\pm$0.01, $-$0.35 $\pm$0.02 $-$0.43 $\pm$0.02, respectively. The
integrated spectral index is flat, $\alpha$(400–700 MHz) = $-$0.49 $\pm$0.01.

##### 5: NGC 4839

The spectral structure of the BCG of the NGC 4839 group shows transverse
spectral steepening, similar to NGC 4789, in addition to gradual spectral
steepening from the flat spectrum radio core toward the northern and southern
radio tails. The two finger-like features emanating toward the southwest have
the steepest spectrum, which is comparable to the low-surface brightness
diffuse emission towards the west, that trails behind the wide-angle-tailed
radio galaxy. The integrated spectral index is $\alpha$(400–700 MHz) = $-$0.90
$\pm$0.02 (see also Sec. 5.4.1, paragraph ‘NGC 4839’ for a detailed
discussion).

##### 15: NGC 4869

Lal (2020b) presented a detailed treatment of the head-tail radio galaxy, NGC
4869. Its radio spectrum shows progressive steepening with increasing distance
from the head because of the effects of radiation losses. They also reported
that the jet bends by $\sim$70∘ with respect to the initial radio tail
direction and there is a clear presence of a ridge, i.e., the flaring of a
straight, collimated radio jet as it crosses a surface brightness edge. The
low-frequency radio emission on either side of this surface brightness edge is
remarkably different in spectral index, $-$1.21 $\pm$0.07 (inside) and $-$1.58
$\pm$0.11 (outside) using our 250–500 MHz and 550-850 MHz band images (see
Fig. 4).

##### 22: 2MASX J13004385$+$2824586

The spectral structure shows spectral steepening from the radio core along the
north and south jets and radio lobes. There are occasional departures from
this simple picture of gradual spectral steepening at the locations of jet
knots, which are the sites of re-acceleration. The integrated spectral index
is steep, $\alpha$(400–700 MHz) = $-$1.17 $\pm$0.04.

###  A.2 Notes on Radio Morphology of Remaining RPS Galaxies

##### (b): GMP 4570

The radio emission peaks at the location of the host galaxy and extends toward
the west, beyond the extent of the optical host, suggesting it is a tailed
radio morphology source. The largest projected linear extent of the source in
the 250–500 MHz band is $\approx$ 7.0 kpc. The source was not covered in our
550–850 MHz band pointings. It was detected in the measurement at 1.4 GHz (see
Table 4, Chen et al., 2020). Thus, the integrated spectral index is
$\alpha$(400–1400 MHz) = $-$0.51 $\pm$0.11, which agrees, within uncertainties
with the upper limit, $\alpha$(400–700 MHz) $\lesssim$ $-$0.98 $\pm$0.52.

##### (e): NGC 4853

(a.k.a. GMP 4156) The 250–500 MHz band image shows slight extensions in radio
emission toward the north, beyond the extent of the optical host, whereas, the
extent in the 550-250 MHz image is similar to the extent of the optical host.
The largest projected linear extent of the source in the 250–500 MHz band is
$\approx$ 7.3 kpc. The integrated spectral index is $\alpha$(400–700 MHz) =
$-$0.77 $\pm$0.12, which agrees, within uncertainties with the measurement at
1.4 GHz (see Table 4, Chen et al., 2020).

##### (k): KUG 1257$+$278

(a.k.a. GMP 3271) Both the 250–500 MHz and 550-250 MHz band images show
extensions in radio emission toward the east, much beyond the extent of the
optical host. The largest projected linear extent of the source in the 250–500
MHz band is $\approx$ 10.6 kpc. The integrated spectral index is
$\alpha$(400–700 MHz) = $-$0.86 $\pm$0.29, which agrees, within uncertainties
with the measurement at 1.4 GHz (see Table 4, Chen et al., 2020).

##### (o): Mrk 60

(a.k.a. D100, GMP 2910) Both, the 250–500 MHz and 550-250 MHz band images show
extensions in radio emission toward the northeast, beyond the extent of the
optical host. The 250–500 MHz band image also shows diffuse extensions toward
the north, providing it an amorphous-like radio morphology, though the 550-250
MHz band image suggests it has a tailed radio morphology. The largest
projected linear extent of the source in the 250–500 MHz band is $\approx$
11.5 kpc. The integrated spectral index is $\alpha$(400–700 MHz) = $-$0.93
$\pm$0.46, which agrees, within uncertainties with the measurement at 1.4 GHz
(see Table 4, Chen et al., 2020).

##### (t): NGC 4921

(a.k.a. GMP 2059) The 250–500 MHz band image suggests it is an irregular-
shaped radio morphology source. The largest projected linear extent of the
source in the 250–500 MHz band is $\approx$ 13.2 kpc. We do not detect it in
our 550-250 MHz band image, but the source was detected in the measurement at
1.4 GHz (see Table 4, Chen et al., 2020). Thus, the integrated spectral index
is $\alpha$(400–1400 MHz) = $-$1.16 $\pm$0.22, which agrees, within
uncertainties with the upper limit, $\alpha$(400–700 MHz) $\lesssim$ $-$1.90
$\pm$0.58.

##  Appendix B Extended Radio Sources: Either with foreground/background
Galaxies or without Redshift Data

Table A1 lists the remaining 111 extended sources, labeled in Fig. A1 that are
either foreground/background galaxies or do not have redshift data. The radio
images of these extended radio sources are presented in Fig. A2, in the order
presented in Table A1. The columns in Table A1 are as follows: (1) source
name; (2–3) probable radio core position, right ascension and declination
(J2000) at the 250–500 MHz; (4) redshift as reported in NED; (5–6) local rms
noise in the near vicinity of the source for the 250–500 MHz and 550–850 MHz
images; (7) the radio morphology of the sources shown in the maps presented;
and (8) alternate name. The source_ID as tabulated in the Table A1 is labeled
in the upper-right corner of each image in Fig. A2. The radio contours in
magenta and blue correspond, respectively, to the 250–500 MHz and 550–850 MHz
band images that are overlaid on the grayscale SDSS (DR12) $r$-band image. We
adopt the definitions of Rudnick (2021) for the classification of radio
sources.

Table A1: Summary of the Nature of Radio Sources in the Coma Cluster Field Using the uGMRT. | Source_ID | Radio Core Position | $z$ | rms | Radio | Alternate Name(s)
---|---|---|---|---|---|---
|  | R.A. (400 MHz) Decl. |  | B-3 | B-4 | Morphology |
|  | (J2000) |  | ($\mu$Jy beam-1) |
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8)
1 |  | 12:51:14.19 |  $+$26:54:40.5 |  | 24 |  | A, D |
2 |  | 12:51:32.67 |  $+$26:42:30.3 |  | 96 |  | CD, FR II |
3 | WISEA J125201.62$+$265126.7 | 12:52:00.51 |  $+$26:51:25.1 | 0.40942 | 48 |  | Tr |
4 |  | 12:52:10.94 |  $+$26:59:50.7 |  | 18 |  | D, Tr |
5 | WISEA J125211.65$+$265649.1 | 12:52:11.64 |  $+$26:56:51.6 | 0.90399 | 24 |  | CD |
6 | WISEA J125245.04$+$270920.3 | 12:52:45.10 |  $+$27:09:20.6 | 0.60126 | 24 | 12 | Tr |
7 |  | 12:52:54.36 |  $+$27:32:03.5 |  | 24 | 24 | CD, FR II |
8 | WISEA J125302.24$+$262722.3 | 12:53:02.23 |  $+$26:27:21.9 | 1.26153 | 96 |  | CD, FR II |
9 |  | 12:53:06.86 |  $+$27:46:08.3 |  | 192 | 96 | FD, FR II |
10 |  | 12:53:13.02 |  $+$27:16:00.9 |  | 24 | 24 | CD, FR II |
11 |  | 12:53:29.57 |  $+$27:04:45.5 |  | 48 | 56 | Tr |
12 |  | 12:53:29.94 |  $+$27:36:48.3 |  | 48 | 36 | A, D |
13 | WISEA J125332.57$+$270050.0 | 12:53:31.64 |  $+$27:00:59.3 | 2.04431 | 24 | 12 | CD, FR II |
14 |  | 12:53:52.46 |  $+$26:43:02.0 |  | 24 | 12 | Tr, FR II |
15 | WISEA J125405.51$+$263028.2 | 12:54:07.09 |  $+$26:30:14.1 | 0.16842 | 192 | 96 | CD, FR II |
16 | Coma A | 12:54:12.01 |  $+$27:37:34.0 | 0.08534 | 768 | 384 | FD, FR II | 3C 277.3, 4C $+$27.22
17 |  | 12:54:12.26 |  $+$26:46:24.7 |  | 24 | 12 | BT |
18 | WISEA J125413.96$+$264153.8 | 12:54:11.78 |  $+$26:42:14.4 | 0.00007 | 24 | 12 | A |
19 | SDSS J125416.43$+$271556.4 | 12:54:16.42 |  $+$27:15:56.1 | 0.29825 | 36 | 18 | HT, WAT |
20 | WISEA J125432.27$+$263453.4 | 12:54:34.33 |  $+$26:35:43.7 |  | 36 | 18 | D, Tr |
21 |  | 12:54:50.88 |  $+$27:56:31.3 |  | 48 | 48 | CD |
22 | WISEA J125458.24$+$271513.5 | 12:54:58.21 |  $+$27:15:12.8 | 0.25733 | 36 | 18 | A, D |
23 | WISEA J125501.22$+$270222.8 | 12:55:02.00 |  $+$27:02:23.8 | 0.45838 | 24 | 12 | HT, WAT |
24 | 5C 04.025∗ | 12:55:03.50 |  $+$27:54:13.7 | 0.40920 | 48 | 48 | CD. FR II |
25 |  | 12:55:10.55 |  $+$27:35:43.1 |  | 36 | 48 | CD |
26 |  | 12:55:12.70 |  $+$26:59:21.7 |  | 24 | 18 | A |
27 | WISEA J125520.65$+$271408.1∗ | 12:55:20.62 |  $+$27:14:09.1 | 1.76500 | 36 | 24 | CD, FR II |
28 | WISEA J125519.16$+$272305.3 | 12:55:21.03 |  $+$27:22:31.4 |  | 24 | 36 | CD, FR II |
29 | SDSS J125523.89$+$265640.9 | 12:55:24.72 |  $+$26:56:40.2 | 0.43852 | 24 | 24 | BT |
30 | MCG $+$05$-$31$-$007 | 12:55:25.05 |  $+$27:47:53.0 |  | 36 | 48 | CD, FR II |
31 | AGC 228097 | 12:55:25.70 |  $+$26:51:04.6 |  | 24 | 12 | CD, FR II | LEDA 5060293
32 |  | 12:55:26.75 |  $+$26:21:28.1 |  | 48 | 12 | CD, FR II |
33 | SDSS J125526.52$+$273804.7∗ | 12:55:27.62 |  $+$27:38:07.8 | 0.10645 | 24 | 24 | BT |
34 | WISEA J125537.60$+$262540.4 | 12:55:36.80 |  $+$26:25:45.7 | 0.42347 | 36 | 12 | A, D |
35 |  | 12:55:37.21 |  $+$26:29:10.3 |  | 24 | 12 | CD |
36 |  | 12:55:46.32 |  $+$27:08:30.2 |  | 24 | 12 | A, D |
37 |  | 12:55:46.72 |  $+$27:03:51.0 |  | 24 | 18 | CD |
38 |  | 12:55:48.22 |  $+$27:17:02.4 |  | 24 | 18 | CD, FR II |
39 |  | 12:55:55.48 |  $+$27:41:27.2 |  | 96 | 96 | A, D |
40 | SDSS J125556.79$+$270957.1 | 12:55:56.26 |  $+$27:09:58.7 | 0.53605 | 24 | 12 | A, D |
41 | WISEA J125601.82$+$274525.3∗ | 12:56:00.96 |  $+$27:45:15.3 | 2.05500 | 24 | 24 | A, D |
42 |  | 12:56:01.81 |  $+$27:32:05.3 |  | 24 | 12 | CD |
43 | WISEA J12560986$+$2750393 | 12:56:09.86 |  $+$27:50:39.3 |  | 24 | 48 | CD |
44 |  | 12:56:19.34 |  $+$28:10:41.4 |  | 48 |  | CD |
45 | WISEA J125619.70$+$271940.2∗ | 12:56:19.49 |  $+$27:19:33.9 | 0.07003 | 24 | 12 | BT, CD |
46 |  | 12:56:24.40 |  $+$27:02:36.1 |  | 24 | 48 | W |
47 |  | 12:56:38.25 |  $+$27:29:02.7 |  | 24 | 12 | Z |
48 |  | 12:56:50.38 |  $+$26:43:53.4 |  | 48 | 18 | CD |
49 |  | 12:56:52.88 |  $+$26:39:43.0 |  | 48 | 48 | CD |
50 | WISEA J125657.08$+$264742.6 | 12:56:57.08 |  $+$26:47:43.1 | 0.63894 | 24 | 18 | A, D |
51 | WISEA J125708.10$+$274853.4∗ | 12:57:06.17 |  $+$27:49:03.9 | 0.23997 | 24 | 12 | Tr, D |
52 |  | 12:57:08.06 |  $+$27:52:51.9 |  | 24 | 12 | BT, FR I |
53 |  | 12:57:25.97 |  $+$27:44:40.3 |  | 24 | 12 | CD, Tr |
54 |  | 12:57:28.95 |  $+$27:56:31.3 |  | 18 |  | CD |
55 | WISEA J125740.06$+$282701.9 | 12:57:40.00 |  $+$28:27:00.5 | 0.41283 | 24 |  | BT |
56 | SDSS J125739.29$+$282012.3 | 12:57:40.29 |  $+$28:20:25.0 | 0.55437 | 36 |  | CD |
57 | WISEA J125752.93$+$280609.4 | 12:57:52.76 |  $+$28:06:07.6 | 0.45360 | 48 | 48 | CD |
58 |  | 12:57:54.73 |  $+$26:59:10.0 |  | 24 | 12 | BT, FR II |
59 | SDSS J125803.78$+$275601.7 | 12:58:03.31 |  $+$27:56:11.0 | 0.26110 | 24 | 24 | Tr |
60 | WISEA J125801.49$+$273006.0 | 12:58:04.45 |  $+$27:30:45.3 |  | 24 | 12 | Tr, FR II |
61 |  | 12:58:04.51 |  $+$27:50:23.8 |  | 24 | 18 | A, D |
62 | WISEA J125812.36$+$273534.7∗ | 12:58:12.33 |  $+$27:35:33.6 | 0.44673 | 24 | 24 | CD, FR II |
| Source_ID | Radio core position | $z$ | rms | Radio | Alternate name(s)
---|---|---|---|---|---|---
|  | R.A. (400 MHz) Dec. |  | B-3 | B-4 | morphology |
|  | (J2000) |  | ($\mu$Jy beam-1) |
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8)
63 |  | 12:58:21.50 |  $+$27:22:01.1 |  | 24 | 18 | A, BT |
64 | 5C 04.064 | 12:58:21.69 |  $+$27:01:38.0 |  | 36 | 24 | CD |
65 | 5C 04.065 | 12:58:23.12 |  $+$26:56:12.7 |  | 48 | 48 | CD | 7C 1255$+$2712
66 |  | 12:58:28.08 |  $+$27:00:43.4 |  | 24 | 18 | CD |
67 | WISEA J125829.96$+$275818.0∗ | 12:58:29.97 |  $+$27:58:17.3 | 1.68500 | 24 | 12 | Tr |
68 | 2MASX J12583190$+$2802587 | 12:58:31.91 |  $+$28:02:58.6 |  | 12 | 12 | A, D |
69 | WISEA J125838.15$+$274921.2 | 12:58:34.55 |  $+$27:49:17.2 |  | 24 | 12 | Tr |
70 |  | 12:58:37.14 |  $+$28:27:55.0 |  | 24 |  | A |
71 | SDSS J125838.32$+$272258.2∗ | 12:58:38.10 |  $+$27:23:03.6 | 1.39500 | 24 | 36 | CD |
72 | 2MASX J12583860$+$2756356 | 12:58:38.44 |  $+$27:56:29.3 | 0.15680 | 12 | 12 | A, D |
73 | WISEA J125838.69$+$270047.6 | 12:58:40.54 |  $+$27:01:12.9 |  | 24 | 36 | BT |
74 | WISEA J125840.28$+$283425.5 | 12:58:40.75 |  $+$28:35:03.2 |  | 24 |  | Tr |
75 |  | 12:58:41.87 |  $+$27:54:09.2 |  | 48 | 36 | FD |
76 | WISEA J125846.09$+$273009.2 | 12:58:46.01 |  $+$27:30:07.2 | 0.28481 | 24 | 24 | WAT |
77 |  | 12:58:51.30 |  $+$26:49:40.9 |  | 36 |  | Tr |
78 | WISEA J125856.74$+$274057.7∗ | 12:58:55.62 |  $+$27:41:05.4 | 0.28578 | 24 | 24 | CD, FR II |
79 |  | 12:58:57.00 |  $+$27:25:41.0 |  | 24 | 48 | CD |
80 | WISEA J125859.32$+$274644.9 | 12:58:59.29 |  $+$27:46:44.3 |  | 96 | 24 | Tr, FR II |
81 | WISEA J125903.24$+$281200.2 | 12:59:03.24 |  $+$28:12:00.2 |  | 36 | 18 | CD, FR II |
82 | 2MASX J12592846$+$2805078 | 12:59:28.46 |  $+$28:05:07.4 | 0.01241 | 18 | 12 | CD |
83 | 5C 04.084 | 12:59:30.64 |  $+$27:01:45.2 |  | 36 |  | A | C3B-217∗∗
84 |  | 12:59:40.05 |  $+$28:44:33.0 |  | 24 |  | CD |
85 | WISEA J125945.22$+$272703.6 | 12:59:42.18 |  $+$27:27:20.8 |  | 24 | 24 | CD |
86 | WISEA J125945.22$+$272703.6 | 12:59:44.11 |  $+$27:26:41.7 |  | 24 | 24 | CD |
87 |  | 12:59:49.41 |  $+$28:24:32.8 |  | 24 | 12 | CD |
88 | WISEA J130010.42$+$273540.9 | 13:00:13.91 |  $+$27:35:53.2 |  | 24 | 18 | CD, FR II |
89 | WISEA J130016.16$+$274838.8 | 13:00:15.10 |  $+$27:48:39.7 | 0.22373 | 24 | 12 | CD, FR II |
90 |  | 13:00:24.60 |  $+$27:11:09.8 |  | 96 |  | A, D |
91 | WISEA J130024.14$+$280927.8 | 13:00:26.28 |  $+$28:09:23.4 | 2.17935 | 48 | 24 | A, BT | 5C 04.102
92 | IC 4033 | 13:00:28.39 |  $+$27:58:20.7 |  | 18 | 12 | A, D |
93 | 5C 04.104 | 13:00:30.36 |  $+$27:11:27.6 |  | 48 |  | A |
94 | WISEA J130032.97$+$272225.3 | 13:00:31.10 |  $+$27:22:37.0 | 0.72957 | 36 |  | FD |
95 | SSTSL2J130031.07$+$283300.0 | 13:00:31.43 |  $+$28:33:00.5 | 0.22103 | 24 |  | Tr |
96 | 5C 04.114 | 13:00:50.92 |  $+$28:08:03.8 |  | 96 | 48 | FD |
97 | WISEA J130106.38$+$281813.0 | 13:01:06.35 |  $+$28:18:09.1 | 0.37339 | 24 | 36 | CD, FR II |
98 | WISEA J130114.14$+$272859.1 | 13:01:12.45 |  $+$27:28:35.5 |  | 18 |  | CD |
99 | WISEA J130113.14$+$281429.5 | 13:01:13.32 |  $+$28:14:27.6 | 0.28795 | 24 | 24 | Z |
100 |  | 13:01:14.03 |  $+$27:51:41.7 |  | 18 | 18 | CD |
101 | WISEA J130121.84$+$280726.7 | 13:01:21.25 |  $+$28:07:22.6 | 2.26500 | 36 | 48 | FD |
102 |  | 13:01:22.28 |  $+$27:58:50.9 |  | 24 | 18 | Tr |
103 | WISEA J130131.35$+$280334.8∗ | 13:01:31.44 |  $+$28:03:35.9 | 0.58188 | 24 | 24 | CD |
104 |  | 13:01:43.02 |  $+$27:48:11.6 |  | 24 |  | CD |
105 | 2MASX J13015023$+$2753367 | 13:01:50.22 |  $+$27:53:36.9 |  | 12 |  | A, D |
106 | WISEA J130153.52$+$273604.3 | 13:01:52.32 |  $+$27:36:06.7 | 0.15856 | 12 |  | CD |
107 |  | 13:01:58.86 |  $+$28:29:27.1 |  | 24 |  | A, D |
108 | WISEA J130220.42$+$275159.8 | 13:02:20.94 |  $+$27:52:10.7 | 0.25082 | 18 |  | A, D |
109 | WISEA J130232.28$+$280117.0 | 13:02:32.74 |  $+$28:01:19.0 | 0.16059 | 24 |  | CD |
110 | TT 50 | 13:02:41.52 |  $+$28:08:10.7 | 0.16446 | 36 |  | HT, NAT |
111 | NGC 4931 | 13:03:00.88 |  $+$28:01:56.9 | 0.01816 | 24 |  | CD, BT | UGC 08154, CGCG 160-118
---
Figure A1: Mosaic image of three pointings at an angular resolution of
$\sim$6$\farcs$1 at the 250–500 MHz band of uGMRT, described in Table 2. The
census of extended sources that are mapped in fields of view of the Coma
cluster, listed in Table A1. The magenta points mark the radio positions and
their sources_IDs are depicted in blue, adjacent to the extended sources. The
grayscale image is displayed in logarithmic scales to emphasize the extended,
low-surface brightness diffuse radio emission and radio emission associated
with the radio galaxies.

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