title: GRB 050505: A high redshift burst discovered by Swift

abstract:
  We report the discovery and subsequent multi-wavelength afterglow behaviour
of the high redshift (z = 4.27) Gamma Ray Burst GRB 050505. This burst is the
third most distant burst, measured by spectroscopic redshift, discovered after
GRB 000131 (z = 4.50) and GRB 050904 (z = 6.29). GRB 050505 is a long GRB with
a multipeaked gamma-ray light curve, with a duration of T_90 = 63+/-2 s and an
inferred isotropic release in gamma-rays of ~4.44 x 10^53 ergs in the 1-10^4
keV rest frame energy range. The Swift X-Ray Telescope followed the afterglow
for 14 days, detecting two breaks in the light curve at 7.4(+/-1.5) ks and 58.0
(+9.9/-15.4) ks after the burst trigger. The power law decay slopes before,
between and after these breaks were 0.25 (+0.16/-0.17), 1.17 (+0.08/-0.09) and
1.97 (+0.27/-0.28) respectively. The light curve can also be fit with a
`smoothly broken' power law model with a break observed at ~ T+18.5 ks, with
decay slopes of ~0.4 and ~1.8 before and after the break respectively. The
X-ray afterglow shows no spectral variation over the course of the Swift
observations, being well fit with a single power law of photon index ~1.90.
This behaviour is expected for the cessation of continued energisation of the
ISM shock followed by a break caused by a jet, either uniform or structured.
Neither break is consistent with a cooling break. The spectral energy
distribution indeed shows the cooling frequency to be below the X-ray but above
optical frequencies. The optical -- X-ray spectrum also shows that there is
significant X-ray absorption in excess of that due to our Galaxy but very
little optical/UV extinction, with E(B-V) ~0.10 for a SMC-like extinction
curve.


title:
Testing the inverse-Compton catastrophe scenario in the intra-day
  variable blazar S5 0716+71. I. Simultaneous broadband observations during
  November 2003

abstract:
  Some intra-day variable, compact extra-galactic radio sources show brightness
temperatures severely exceeding 10^{12} K, the limit set by catastrophic
inverse-Compton (IC) cooling in sources of incoherent synchrotron radiation.
The violation of the IC limit, possible under non-stationary conditions, would
lead to IC avalanches in the soft-gamma-ray energy band during transient
periods. For the first time, broadband signatures of possible IC catastrophes
were searched for in S5 0716+71. A multifrequency observing campaign targetting
S5 0716+71 was carried out in November 2003 under the framework of the European
Network for the Investigation of Galactic nuclei through Multifrequency
Analysis (ENIGMA) together with a campaign by the Whole Earth Blazar Telescope
(WEBT), involving a pointing by the soft-gamma-ray satellite INTEGRAL, optical,
near-infrared, sub-millimeter, millimeter, radio, and Very Long Baseline Array
(VLBA) monitoring. S5 0716+71 was very bright at radio frequencies and in a
rather faint optical state during the INTEGRAL pointing; significant inter-day
and low intra-day variability was recorded in the radio regime, while typical
fast variability features were observed in the optical band. No correlation was
found between the radio and optical emission. The source was not detected by
INTEGRAL, neither by the X-ray monitor JEM-X nor by the gamma-ray imager ISGRI,
but upper limits to the source emission in the 3-200 keV energy band were
estimated. A brightness temperature Tb>2.1x10^{14} K was inferred from the
radio variability, but no corresponding signatures of IC avalanches were
recorded at higher energies. The absence of IC-catastrophe signatures provides
either a lower limit delta>8 to the Doppler factor affecting the radio emission
or strong constraints for modelling of the Compton catastrophes in S5 0716+71.


title:
A Shack-Hartmann wavefront sensor projected onto the sky with reduced
  focal anisoplanatism

abstract:
  A method for producing a laser guide star wavefront sensor for adaptive
optics with reduced focal anisoplanatism is presented. A theoretical analysis
and numerical simulations have been carried out and the results are presented.
The technique, named SPLASH (Sky-Projected Laser Array Shack-Hartmann), is
shown to suffer considerably less from focal anisoplanatism than a conventional
laser guide star system. The method is potentially suitable for large telescope
apertures (~8m), and possibly for extremely large telescopes.


title:
The emission spectrum of the strong Fe II emitter BAL Seyfert 1 galaxy
  IRAS 07598+6508

abstract:
  The narrow-line Seyfert 1 galaxy IRAS 07598+6508 is known to be a stong Fe II
emitter. The analysis of several high S/N ratio spectra shows that its spectrum
is dominated by a relatively narrow "broad line" region (1 780 km s$^{-1}$
FWHM) emitting not only Fe II, but also Ti II and Cr II lines. Although we were
unable to find a completely satisfactory physical model, we got the best
agreement with the observations with collisional rather than radiative models,
with a high density (n=10$^{15}$ cm$^{-3}$), a high column density
(N$_{H}$=10$^{25}$ cm$^{-2}$) and a microturbulence of 100 km s$^{-1}$. This
BLR is qualitatively similar to the one observed in I Zw 1. We have not found
traces in IRAS 07598+6508 of the narrow line regions found in I Zw 1.


title:
The Millennium Galaxy Catalogue: morphological classification and
  bimodality in the colour-concentration plane

abstract:
  Using 10 095 galaxies (B < 20 mag) from the Millennium Galaxy Catalogue, we
derive B-band luminosity distributions and selected bivariate brightness
distributions for the galaxy population. All subdivisions extract highly
correlated sub-sets of the galaxy population which consistently point towards
two overlapping distributions. A clear bimodality in the observed distribution
is seen in both the rest-(u-r) colour and log(n) distributions. The rest-(u-r)
colour bimodality becomes more pronounced when using the core colour as opposed
to global colour. The two populations are extremely well separated in the
colour-log(n) plane. Using our sample of 3 314 (B < 19 mag) eyeball classified
galaxies, we show that the bulge-dominated, early-type galaxies populate one
peak and the bulge-less, late-type galaxies occupy the second. The early- and
mid-type spirals sprawl across and between the peaks. This constitutes
extremely strong evidence that the fundamental way to divide the luminous
galaxy population is into bulges and discs and that the galaxy bimodality
reflects the two component nature of galaxies and not two distinct galaxy
classes. We argue that these two-components require two independent formation
mechanisms/processes and advocate early bulge formation through initial
collapse and ongoing disc formation through splashback, infall and
merging/accretion. We calculate the B-band luminosity-densities and
stellar-mass densities within each subdivision and estimate that the z ~ 0
stellar mass content in spheroids, bulges and discs is 35 +/- 2 per cent, 18
+/- 7 and 47 +/- 7 per cent respectively. [Abridged]


title: Size and Orientation of the `Z' in ZRGs

abstract:
  Some X-shaped radio galaxies (XRGs) show a Z-symmetric morphology in the less
luminous secondary lobes. Our geometrical arguments strongly support a merger
of two galaxies as mechanism for the formation of these sources (ZRG). They
also strengthen the conjecture that a jet is aligned with the spin of the BH at
its base and that the jet flips into the direction of the orbital angular
momentum of the pre-merger binary black hole (BHB). We could also restrict the
distance where the pre-merger jet is bent into Z-shape by the inspiralling
galaxy to the range of 30-100 kpc. One of three possible orientations of the
jet relative to our line of sight is more likely than the others and allows us
to deduce the direction of the spin of the merged BH. The existence of XRGs and
ZRGs proves that the binary has merged, contrary to previous speculations that
after a merger of two galaxies the decay of the BHB stalls due to loss cone
depletion. In ZRGs the black holes probably merge on timescales of some 10^8 yr
after the bending of the jet in a distance of about 50 kpc. Thus, in a way, the
bending starts a stop watch for the rest of the merger.


title:
Evidence that Quasars and Related Active Galaxies are Good Radio
  Standard Candles and that they are Likely to be a Lot Closer than their
  Redshifts Imply

abstract:
  For many years some astronomers have continued to argue, using redshift
periodicities and quasar-galaxy associations, that quasars may be closer than
their redshifts imply. Here, for the first time using raw radio data, I
re-examine this question and find new evidence that supports this argument.
Using VLBA flux densities and angular motions in jets, I show that the central
engine of quasars and BL Lac objects appears to be a good radio standard
candle. Using this information, relative distances are calculated and absolute
radio distances are then obtained by referencing to a source whose true
distance has been obtained using Cepheid variables. The results reveal that in
this model most of the strong radio sources found in early surveys are nearer
than 100 Mpc. (abridged)


title:
Non-thermal Cosmic Backgrounds and prospects for future high-energy
  observations of blazars

abstract:
  We discuss the contribution of the blazar population to the extragalactic
background radiation across the electromagnetic (e.m.) spectrum with particular
reference to the microwave, hard-X-ray and gamma-ray bands. Our estimates are
based on a recently derived blazar radio LogN-LogS that was built by combining
several radio and multi-frequency surveys. We show that blazar emission
integrated over cosmic time gives rise to a considerable broad-band non-thermal
cosmic background that dominates the extragalactic brightness in the
high-energy part of the e.m. spectrum. We also estimate the number of blazars
that are expected to be detected by future planned or hypothetical missions
operating in the X-ray and gamma-ray energy bands.


title: Pro-Am Collaboration and the AAVSO

abstract:
  Professionals need to be aware that there is a valuable resource available
and waiting to be used - the amateur astronomy community. We give some examples
of how pro-am collaborations have worked in the past, indicate the advantages
and disadvantages of such collaborations, and suggest methods by which a
professional can find and work effectively with amateur astronomers.


title: Testing Accretion Disk Theory in Black Hole X-ray Binaries

abstract:
  We present results from spectral modeling of three black hole X-ray binaries:
LMC X-3, GRO J1655-40, and XTE J1550-564. Using a sample of disk dominated
observations, we fit the data with a range of spectral models that includes a
simple multitemperature blackbody (DISKBB), a relativistic accretion disk model
based on color-corrected blackbodies (KERRBB), and a relativistic model based
on non-LTE atmosphere models within an alpha prescription (BHSPEC). BHSPEC
provides the best fit for a BeppoSAX observation of LMC X-3, which has the
broadest energy coverage of our sample. It also provides the best fit for
multiple epochs of Rossi X-ray Timing Explorer (RXTE) data in this source,
except at the very highest luminosity (L/L_{Edd} >~ 0.7), where additional
physics must be coming into play. BHSPEC is also the best-fit model for
multi-epoch RXTE observations of GRO J1655-40 and XTE J1550-564, although the
best-fit inclination of the inner disk differs from the binary inclination. All
our fits prefer alpha=0.01 to alpha=0.1, in apparent disagreement with the
large stresses inferred from the rapid rise times observed in outbursts of
these two sources. In all three sources our fits imply moderate black hole
spins (a/M ~ 0.1 - 0.8), but this is sensitive to the reliability of
independent measurements of these system parameters and to the physical
assumptions which underly our spectral models.


title: Infrared Dark Clouds: precursors to star clusters

abstract:
  Infrared Dark Clouds (IRDCs) are dense molecular clouds seen as extinction
features against the bright mid-infrared Galactic background. Millimeter
continuum maps toward 38 IRDCs reveal extended cold dust emission to be
associated with each of the IRDCs. IRDCs range in morphology from filamentary
to compact and have masses of 120 to 16,000 Msun, with a median mass of ~940
Msun. Each IRDC contains at least one compact (<=0.5 pc) dust core and most
show multiple cores. We find 140 cold millimeter cores unassociated with MSX
8um emission. The core masses range from 10 to 2,100 Msun, with a median mass
of ~120 Msun. The slope of the IRDC core mass spectrum (alpha ~ 2.1 +/- 0.4) is
similar to that of the stellar IMF. Assuming that each core will form a single
star, the majority of the cores will form OB stars. IRDC cores have similar
sizes, masses, and densities as hot cores associated with individual, young
high-mass stars, but they are much colder. We therefore suggest that IRDC
represent an earlier evolutionary phase in high-mass star formation. In
addition, because IRDCs contain many compact cores, and have the same sizes and
masses as molecular clumps associated with young clusters, we suggest that
IRDCs are the cold precursors to star clusters. Indeed, an estimate of the star
formation rate within molecular clumps with similar properties to IRDCs (~2
Msun/yr) is comparable to the global star formation rate in the Galaxy,
supporting the idea that all stars may form in such clumps.


title: Turbulent Velocity Fields in SPH--simulated Galaxy Clusters

abstract:
  We present a study of the turbulent velocity fields in the Intra Cluster
Medium of a sample of 21 galaxy clusters simulated by the SPH--code Gadget2,
using a new numerical scheme where the artificial viscosity is suppressed
outside shocks. The turbulent motions in the ICM of our simulated clusters are
detected with a novel method devised to better disentangle laminar bulk motions
from chaotic ones. We focus on the scaling law between the turbulent energy
content of the gas particles and the total mass, and find that the energy in
the form of turbulence scales approximatively with the thermal energy of
clusters. We follow the evolution with time of the scaling laws and discuss the
physical origin of the observed trends. The simulated data are in agreement
with independent semi--analytical calculations, and the combination between the
two methods allows to constrain the scaling law over more than two decades in
cluster mass.


title:
The DEEP2 Galaxy Redshift Survey: Mean Ages and Metallicities of Red
  Field Galaxies at z ~ 0.9 from Stacked Keck/DEIMOS Spectra

abstract:
  As part of the DEEP2 galaxy redshift survey, we analyze absorption line
strengths in stacked Keck/DEIMOS spectra of red field galaxies with weak to no
emission lines, at redshifts 0.7 <= z <= 1. Comparison with models of stellar
population synthesis shows that red galaxies at z ~ 0.9 have mean
luminosity-weighted ages of the order of only 1 Gyr and at least solar
metallicities. This result cannot be reconciled with a scenario where all stars
evolved passively after forming at very high z. Rather, a significant fraction
of stars can be no more than 1 Gyr old, which means that star formation
continued to at least z ~ 1.2. Furthermore, a comparison of these distant
galaxies with a local SDSS sample, using stellar populations synthesis models,
shows that the drop in the equivalent width of Hdelta from z ~ 0.9 to 0.1 is
less than predicted by passively evolving models. This admits of two
interpretations: either each individual galaxy experiences continuing low-level
star formation, or the red-sequence galaxy population from z ~ 0.9 to 0.1 is
continually being added to by new galaxies with younger stars.


title: Young, Low-Mass Brown Dwarfs with Mid-Infrared Excesses

abstract:
  We have combined new I, J, H, and Ks imaging of portions of the Chamaeleon
II, Lupus I, and Ophiuchus star-forming clouds with 3.6 to 24 micron imaging
from the Spitzer Legacy Program, "From Molecular Clouds to Planet Forming
Disks", to identify a sample of 19 young stars, brown dwarfs and sub-brown
dwarfs showing mid-infrared excess emission. The resulting sample includes
sources with luminosities of 0.5>log(L/Lsun)>-3.1. Six of the more luminous
sources in our sample have been previously identified by other surveys for
young stars and brown dwarfs. Five of the sources in our sample have nominal
masses at or below the deuterium burning limit (~12 M_J). Over three decades in
luminosity, our sources have an approximately constant ratio of excess to
stellar luminosity. We compare our observed SEDs to theoretical models of a
central source with a passive irradiated circumstellar disk and test the
effects of disk inclination, disk flaring, and the size of the inner disk hole
on the strength/shape of the excess. The observed SEDs of all but one of our
sources are well fit by models of flared and/or flat disks.


title:
Late-Time Spectroscopy of SN 2002cx: The Prototype of a New Subclass of
  Type Ia Supernovae

abstract:
  We present Keck optical spectra of SN 2002cx, the most peculiar known Type Ia
supernova (SN Ia), taken 227 and 277 days past maximum light. Astonishingly,
the spectra are not dominated by the forbidden emission lines of iron that are
a hallmark of thermonuclear supernovae in the nebular phase. Instead, we
identify numerous P-Cygni profiles of Fe II at very low expansion velocities of
about 700 km/s, which are without precedent in SNe Ia. We also report the
tentative identification of low-velocity O I in these spectra, suggesting the
presence of unburned material near the center of the exploding white dwarf. SN
2002cx is the prototype of a new subclass of SNe Ia, with spectral
characteristics that may be consistent with recent pure deflagration models of
Chandrasekhar-mass thermonuclear supernovae. These are distinct from the
majority of SNe Ia, for which an alternative explosion mechanism, such as a
delayed detonation, may be required.


title: Likelihood Functions for Galaxy Cluster Surveys

abstract:
  Galaxy cluster surveys offer great promise for measuring cosmological
parameters, but survey analysis methods have not been widely studied. Using
methods developed decades ago for galaxy clustering studies, it is shown that
nearly exact likelihood functions can be written down for galaxy cluster
surveys. The sparse sampling of the density field by galaxy clusters allows
simplifications that are not possible for galaxy surveys. An application to
counts in cells is explicitly tested using cluster catalogs from numerical
simulations and it is found that the calculated probability distributions are
very accurate at masses above several times 10^{14}h^{-1} solar masses at z=0
and lower masses at higher redshift.


title:
The ESO-Spitzer Imaging extragalactic Survey (ESIS) I: WFI B,V,R deep
  observations of ELAIS-S1 and comparison to Spitzer and GALEX data

abstract:
  The ESO-Spitzer extragalactic Imaging Survey (ESIS) is the optical follow up
of the Spitzer Wide-Area InfraRed Extragalactic (SWIRE) survey in the ELAIS-S1
area. This paper presents B, V, R Wide Field Imager observations of the first
1.5 square degree of the ESIS survey. Data reduction is described including
astrometric calibration, illumination and color corrections, completeness and
photometric accuracy estimates. Number counts and color distributions are
compared to literature observational and theoretical data, including
non-evolutionary, PLE, evolutionary and semi-analytic Lambda-CDM galaxy models,
as well as Milky Way stellar predictions. ESIS data are in good agreement with
previous works and are best reproduced by evolutionary and hierarchical
Lambda-CDM scenarios. The ELAIS-S1 area benefits from extensive follow-up from
X-ray to radio frequencies: some potential uses of the multi-wavelength
observations are illustrated. Optical-Spitzer color-color plots promise to be
very powerful tools to disentangle different classes of sources (e.g. AGNs,
starbursts, quiescent galaxies). Ultraviolet GALEX data are matched to optical
and Spitzer samples, leading to a discussion of galaxy properties in the
UV-to-24 microns color space. The spectral energy distribution of a few
objects, from the X-rays to the far-IR are presented as examples of the
multi-wavelength study of galaxy emission components in different spectral
domains.


title: Relativistic Radiative Flow in a Luminous Disk

abstract:
  Radiatively driven transfer flow perpendicular to a luminous disk was
examined under a fully special relativistic treatment, taking into account
radiation transfer. The flow was assumed to be vertical, and the gravity, the
gas pressure, and the viscous heating were ignored. In order to construct the
boundary condition at the flow top, the magic speed above the flat source was
re-examined, and it was found that the magic speed above a moving source can
exceed that above a static source ($\sim 0.45~c$). Then, the radiatively driven
flow in a luminous disk was numerically solved, from the flow base (disk
``inside''), where the flow speed is zero, to the flow top (disk ``surface''),
where the optical depth is zero. For a given optical depth and appropriate
initial conditions at the flow base, where the flow starts, a loaded mass in
the flow was obtained as an eigenvalue of the boundary condition at the flow
top. Furthermore, a loaded mass and the flow final speed at the flow top were
obtained as a function of the radiation pressure at the flow base; the flow
final speed increases as the loaded mass decreases. Moreover, the flow velocity
and radiation fields along the flow were obtained as a function of the optical
depth. Within the present treatment, the flow three velocity $v$ is restricted
to be within the range of $v < c/\sqrt{3}$, which is the relativistic sound
speed, due to the relativistic effect.


title: Velocity-Dependent Eddington Factor in Relativistic Radiative Flow

abstract:
  We propose a variable Eddington factor, depending on the {\it flow velocity}
$v$, for the relativistic radiative flow, whose velocity becomes of the order
of the speed of light. When the gaseous flow is radiatively accelerated up to
the relativistic regime, the velocity gradient becomes very large in the
direction of the flow. As a result, the radiative diffusion may become {\it
anisotropic} in the comoving frame of the gas. Hence, in a flow that is
accelerated from subrelativistic to relativistic regimes, the Eddington factor
should be different from 1/3 even in the diffusion limit. As a simple form, the
velocity-dependent Eddington factor may be written as $f(\beta) =
1/3+(2/3)\beta$, where $\beta=v/c$. Using the velocity-dependent Eddington
factor, we can solve the rigorous equations of the relativistic radiative flow
accelerated up to the relativistic speed. We also propose a generalized form
for a variable Eddington factor as a function of the optical depth $\tau$ as
well as the flow velocity: %$f(\tau, \beta) = {1/3} + {2/3} %
\frac{1+(\tau+1)\beta}{1+\tau+\beta}$ $f(\tau, \beta) = 1/3 + (2/3)
[{1+(\tau+1)\beta}]/({1+\tau+\beta})$ for a spherically symmetric case. The
velocity-dependent Eddington factor can be used in various relativistic
radiatively-driven flows, such as black-hole accretion flows, relativistic
astrophysical jets and outflows, and relativistic explosions like gamma-ray
bursts.


title: Proper Motion of the Crab Pulsar Revisited

abstract:
  It has been suggested that the Crab pulsar's proper motion is well aligned
with the symmetry axis of the pulsar wind nebula. We have re-visited this
question, examining over 6 years of F547M WFPC2 chip 3 images to obtain a
best-fit value of $\mu_\ast = 14.9 \pm 0.8$mas/yr at PA $278\arcdeg \pm
3\arcdeg$. At $26\arcdeg\pm 3\arcdeg$ to the nebula axis, this substantially
relaxes constraints on the birth kick of this pulsar. Such misalignment allows
the momentum to be imparted over $\sim$1s timescales.


title:
Photometry of seven overlooked open clusters in the First and Fourth
  Galactic Quadrants

abstract:
  CCD BVI photometry is presented for 7 previously unstudied star clusters
projected toward the inner side of the Galaxy: Trumpler 23, Lynga 3, Collinder
307, Ruprecht 134, ESO552SC16, AL 5 and Kronberger 3. Color magnitude diagrams
of the cluster regions allow us to conclude that Lynga 3 and ESO552SC16, are
not clusters, but groups of bright stars probably located in the
Carina-Sagittarius spiral arm. AL 5 and Kronberger 3 are so embedded in a dense
stellar field that we cannot confirm their nature. Trumpler~ 3 and Ruprecht 134
are two intermediate-age open clusters located well inside the solar ring which
deserve further attention. Finally, Collinder 307 is an obscured younger
cluster (250 Myr) located in the Carina-Sagittarius spiral arm. Our results
emphasize the difficulty to search for open clusters in the inner regions of
the Galaxy due to the richness of the field and the patchy nature of the
interstellar absorption, but at the same time significantly contribute to a
better understanding of this complicated regions of the Milky Way.


title: A Physical Model for Co-evolution of QSOs and of their Spheroidal Hosts

abstract:
  At variance with most semi-analytic models, in the Anti-hierarchical Baryon
Collapse scenario (Granato et al. 2001, 2004) the main driver of the galaxy
formation and evolution is not the merging sequence but are baryon processes.
This approach emphasizes, still in the framework of the hierarchical clustering
paradigm for dark matter halos, feedback processes from supernova explosions
and from active nuclei, that tie together star formation in spheroidal galaxies
and the growth of black holes at their centers. We review some recent results
showing the remarkably successful predictive power of this scenario, which
allows us to account for the evolution with cosmic time of a broad variety of
properties of galaxies and active nuclei, which proved to be very challenging
for competing models.


title: TeV Gamma-Ray Observations of the Perseus and Abell 2029 Galaxy Clusters

abstract:
  Galaxy clusters might be sources of TeV gamma rays emitted by high-energy
protons and electrons accelerated by large scale structure formation shocks,
galactic winds, or active galactic nuclei. Furthermore, gamma rays may be
produced in dark matter particle annihilation processes at the cluster cores.
We report on observations of the galaxy clusters Perseus and Abell 2029 using
the 10 m Whipple Cherenkov telescope during the 2003-2004 and 2004-2005
observing seasons. We apply a two-dimensional analysis technique to scrutinize
the clusters for TeV emission. In this paper we first determine flux upper
limits on TeV gamma-ray emission from point sources within the clusters.
Second, we derive upper limits on the extended cluster emission. We
subsequently compare the flux upper limits with EGRET upper limits at 100 MeV
and theoretical models. Assuming that the gamma-ray surface brightness profile
mimics that of the thermal X-ray emission and that the spectrum of cluster
cosmic rays extends all the way from thermal energies to multi-TeV energies
with a differential spectral index of -2.1, our results imply that the cosmic
ray proton energy density is less than 7.9% of the thermal energy density for
the Perseus cluster.


title:
Bolocam Survey for 1.1 mm Dust Continuum Emission in the c2d Legacy
  Clouds. II. Ophiuchus

abstract:
  We present a large-scale millimeter continuum map of the Ophiuchus molecular
cloud. Nearly 11 square degrees, including all of the area in the cloud with
visual extinction more than 3 magnitudes, was mapped at 1.1 mm with Bolocam on
the Caltech Submillimeter Observatory (CSO). By design, the map also covers the
region mapped in the infrared with the Spitzer Space Telescope. We detect 44
definite sources, and a few likely sources are also seen along a filament in
the eastern streamer. The map indicates that dense cores in Ophiuchus are very
clustered and often found in filaments within the cloud. Most sources are
round, as measured at the half power point, but elongated when measured at
lower contour levels, suggesting spherical sources lying within filaments. The
masses, for an assumed dust temperature of 10 K, range from 0.24 to 3.9 solar
masses, with a mean value of 0.96 solar masses. The total mass in distinct
cores is 42 solar masses, 0.5 to 2% of the total cloud mass, and the total mass
above 4 sigma is about 80 solar masses. The mean densities in the cores are
quite high, with an average of 1.6 x 10^6 per cc, suggesting short free-fall
times. The core mass distribution can be fitted with a power law with slope of
2.1 plus or minus 0.3 for M>0.5 solar masses, similar to that found in other
regions, but slightly shallower than that of some determinations of the local
IMF. In agreement with previous studies, our survey shows that dense cores
account for a very small fraction of the cloud volume and total mass. They are
nearly all confined to regions with visual extinction at least 9 mag, a lower
threshold than found previously.


title: Surface Magnetism Effects in Time-Distance Helioseismology

abstract:
  Recent observations of helioseismic holography revealed that magnetic fields
inclined to the line-of-sight direction could cause systematic variations in
measured acoustic phase shifts, and that the surface magnetic field may shift
the phases and impair the coherence of acoustic waves (known as "showerglass
effect"). We examine how these affect time-distance helioseismology
measurements. It is confirmed that the inclined magnetic field could cause
variations in acoustic travel times inside sunspot penumbra, however,
inversions of the measured times show that this effect only slightly shifts the
location of negative sound-speed variations near the solar surface, but does
not change the inverted deeper interior structures. Regarding to the
showerglass effect, we find that outgoing and incoming travel time
perturbations through sunspots are significantly smaller than those reported
from helioseismic holography. In addition, our second-skip cross-correlation
experiments demonstrate that inside sunspots, the half of the double-skip
travel times are very similar to the mean single-skip travel times. We conclude
that these surface magnetism effects do not cause considerable systematic
errors in time-distance helioseismology of active regions.


title:
Stable matter of 4th generation: hidden in the Universe and close to
  detection?

abstract:
  Stable neutrino and U quark of 4th generation are excluded neither by
experimental data, nor by astrophysical constraints. Moreover, excess of stable
$\bar U$ quarks in the Universe can lead to an exciting composite
nuclear-interacting form of dark matter, which can even dominate in large scale
structure formation.


title: Oscillations of starless cores

abstract:
  If the split, asymmetric molecular spectral line profiles that are seen in
many starless cores are interpreted as indicative of global collapse or
expansion of the core then one possible implication is that most starless cores
have short lifetimes on the order of the collapse or sound crossing time scale.
An alternative interpretation of the line profiles as indicative of
perturbations on an underlying equilibrium structure leads to the opposite
implication, that many cores have long lifetimes. While evidence suggests that
some cores are collapsing on a free-fall time scale, we show that observations
of some other starless cores can be reproduced by a model of non-radial
oscillations about the equilibrium configuration of a pressure-bounded,
thermally-supported sphere (Bonnor-Ebert sphere). We model the oscillations as
linear perturbations following a standard analysis developed for stellar
pulsations and compare the column densities and molecular spectral line
profiles predicted from a particular model to observations of the Bok globule
B68.


title:
The old globular cluster system of the dIrr galaxy NGC1427A in the
  Fornax cluster

abstract:
  We present a study of the old globular cluster (GC) population of the dwarf
irregular galaxy NGC 1427A using multi-wavelength VLT observations in U, B, V,
I, H_alpha, J, H, and Ks bands under excellent observing conditions. We applied
color and size selection criteria to select old GC candidates and made use of
archival ACS images taken with the Hubble Space Telescope to reject
contaminating background sources and blended objects from the GC candidates'
list. The H_alpha observations were used to check for contamination due to
compact, highly reddened young star clusters whose colors and sizes could mimic
those of old GCs. After accounting for contamination we obtain a total number
of 38+/-8 GC candidates with colors consistent with an old (~10 Gyr) and
metal-poor (Z < 0.4xZ_solar) population as judged by simple stellar population
models. Our contamination analysis indicates that the density distribution of
GCs in the outskirts of the Fornax central cD galaxy NGC1399 may not be
spherically symmetric. We derive a present-day specific frequency S_N of
1.6+/-0.23 for NGC 1427A, a value significantly larger than what is observed in
the Local Group dwarf irregular galaxies and comparable with the values found
for the same galaxy types in the Virgo and Fornax clusters. Assuming a
universal globular cluster luminosity function turnover magnitude, we derive a
distance modulus to NGC 1427A of 31.01+/-0.21 mag which places it
3.2+/-2.5(statistic)+/-1.6(systematic) Mpc in front of the Fornax central cD
galaxy NGC 1399. The implications of this result for the relationship between
NGC 1427A and the cluster environment are briefly discussed.


title:
Density Perturbation in the Universe with Nontrivial Topology of
  Space-Time

abstract:
  A space spectrum of density perturbation In the Universe with nontrivial
topology of space-time is shown to become discrete.


title: Interstellar cloud structure: The statistics of centroid velocities

abstract:
  The investigation of the statistical properties of maps of line centroids has
been used for almost 50 years, but there is still no general agreement on their
interpretation. We try to quantify which properties of underlying turbulent
velocity fields can be derived from centroid velocity maps, and we test
conditions under which the scaling behaviour of the centroid velocities matches
the scaling of the three-dimensional velocity field. Using fractal cloud models
we study systematically the relation between three-dimensional density and
velocity fields and the statistical properties of the produced line centroid
maps. We put special attention to cases with large density fluctuations
resembling supersonic interstellar turbulence. Starting from the Delta-variance
analysis we derive a new tool to compute the scaling behaviour of the
three-dimensional velocity field from observed intensity and centroid velocity
maps. We provide two criteria to decide whether the information from the
centroid velocities directly reflects the properties of the underlying velocity
field. Applying these criteria allows to understand the different results found
so far in the literature on the interpretation of the statistics of velocity
centroids. A new iteration scheme can be used to derive the three-dimensional
velocity scaling from centroid velocity maps for arbitrary density and velocity
fields, but it requires an accurate knowledge of the average density of the
considered interstellar cloud.


title: MOND habitats within the solar system

abstract:
  MOdified Newtonian Dynamics (MOND) is an interesting alternative to dark
matter in extragalactic systems. We here examine the possibility that mild or
even strong MOND behavior may become evident well inside the solar system, in
particular near saddle points of the total gravitational potential. Whereas in
Newtonian theory tidal stresses are finite at saddle points, they are expected
to diverge in MOND, and to remain distinctly large inside a sizeable oblate
ellipsoid around the saddle point. We work out the MOND effects using the
nonrelativistic limit of the T$e$V$e$S theory, both in the perturbative nearly
Newtonian regime and in the deep MOND regime. While strong MOND behavior would
be a spectacular ``backyard'' vindication of the theory, pinpointing the
MOND-bubbles in the setting of the realistic solar system may be difficult.
Space missions, such as the LISA Pathfinder, equipped with sensitive
accelerometers, may be able to explore the larger perturbative region.


title: Post-Launch Analysis of Swift's Gamma-Ray Burst Detection Sensitivity

abstract:
  The dependence of Swift's detection sensitivity on a burst's temporal and
spectral properties shapes the detected burst population. Using simplified
models of the detector hardware and the burst trigger system I find that Swift
is more sensitive to long, soft bursts than CGRO's BATSE, a reference detector
because of the large burst database it accumulated. Thus Swift has increased
sensitivity in the parameter space region into which time dilation and spectral
redshifting shift high redshift bursts.


title: INTEGRAL observations of the blazar 3C454.3 in outburst

abstract:
  In Spring 2005, the blazar 3C454.3 underwent a dramatic outburst at all
wavelengths from mm to X-rays. This prompted INTEGRAL observations,
accomplished in 15-18 May 2005. The source was detected by the INTEGRAL
instruments from 3 to 200 keV in a bright state (~5 x 10E-10 cgs), at least a
factor of 2-3 higher than previously observed. This is one of the brightest
blazar detections achieved by INTEGRAL. During the 2.5 days of INTEGRAL
monitoring, we detected a ~20% decrease in the hard X-rays (20-40 keV),
indicating that we have sampled the decaying part of the flare. The decrease is
less apparent in the soft X-rays (5-15 keV). The simultaneous optical
variations are weakly correlated with those at soft X-rays, and not clearly
correlated with those at hard X-rays. The spectral energy distribution exhibits
two components, as typically seen in blazars, which can be modeled with
synchrotron radiation and inverse Compton scattering occurring in a region
external to the broad line region.


title:
VLA Observations of Carbon 91$\alpha$ Recombination Line Emission in W49
  North

abstract:
  We have detected C91$\alpha$ (8.5891 GHz) emission toward 4 ultra-compact
\HII regions (\UCHII s; W49G, J, L & C) in the W49 North massive star forming
region with the Very Large Array (VLA) at 3\arcsec resolution. No carbon line
emission was detected toward \UCHII s W49F, A, O, S and Q at this frequency to
a 3$\sigma$ level of 2 mJy. We also observed the same region in the C75$\alpha$
line (15.3 GHz) with no detection at a 3$\sigma$ level of 6 mJy with a
1\arcsec.7 beam. Detection of line emission toward these sources add supporting
data to the earlier result of \nocite{retal05a}Roshi et al (2005a) that many
\UCHII s have an associated photo-dissociation region (PDR). Similarity of the
LSR velocities of carbon recombination lines and H$_2$CO absorption toward
\UCHII s in W49 North suggests that the PDRs reside in the dense interface zone
surrounding these \HII regions. Combining the observed carbon line parameters
at 8.6 GHz with the upper limits on line emission at 15.3 GHz, we obtain
constraints on the physical properties of the PDRs associated with W49G and J.
The upper limit on the number density of hydrogen molecule obtained from carbon
line models is $\sim$ $5 \times 10^6$ \cmthree.


title:
An Experimental setup to develop RFI mitigation techniques for radio
  astronomy

abstract:
  Increasing levels of Radio Frequency Interference (RFI) are a problem for
research in radio astronomy. Various techniques to suppress RFI and extract
astronomical signals from data affected by interference are being tried out.
However, extracting weak astronomical signals in the spectral region affected
by RFI remains a technological challenge. In this paper, we describe the
construction of an experimental setup at the Raman Research Institute (RRI),
Bangalore, India for research in RFI mitigation. We also present some results
of tests done on the data collected using this setup. The experimental setup
makes use of the 1.42 GHz receiver system of the 10.4 m telescope at RRI. A new
reference antenna, its receiver system and a backend for recording digitized
voltage together with the 1.42 GHz receiver system form the experimental setup.
We present the results of the characterization of the experimental setup. An
off-line adaptive filter was successfully implemented and tested using the data
obtained with the experimental setup.


title: Disturbed isolated galaxies: indicators of a dark galaxy population?

abstract:
  We report the results of our search for disturbed (interacting) objects among
very isolated galaxies. The inspections of 1050 northern isolated galaxies from
KIG and 500 nearby, very isolated galaxies situated in the Local Supercluster
yielded five and four strongly disturbed galaxies, respectively. We suggest
that the existence of "dark" galaxies explains the observed signs of
interaction. This assumption leads to a cosmic abundance of dark galaxies (with
the typical masses for luminous galaxies) that is less than ~1/20 the
population of visible galaxies.


title:
X-ray spectral properties of high-redshift radio-loud quasars beyond
  redshift 4--first results

abstract:
  (abridged) We firstly present the results of X-ray spectroscopic observations
with XMM-Newton for four high-redshift radio-loud quasars at z>4. These
observations more than double the number of z>4 radio-loud quasars having X-ray
spectroscopic data to seven, which compose a significant subset of a
flux-limited sample of z>4 radio-loud quasars. Based on this subset we show
some preliminary results on the overall X-ray spectral properties of the
sample. Soft X-ray spectral flattening, which is thought to arise from
intrinsic X-ray absorption, was found in about half of the sample. We give a
preliminary distribution of the absorption column density NH. For those with
detected X-ray absorption, the derived NH values fall into a very narrow range
(around a few times 10^(22)cm^(-2) for `cold' absorption), suggesting a
possible common origin of the absorber. Compared to lower-redshift samples at
z<2, there is an extension, or a systematic shift, toward higher values in the
intrinsic NH distribution at z>4, and an increase of the fraction of radio-loud
quasars showing X-ray absorption toward high redshifts. These results indicate
a cosmic evolution effect, which seems to be the strongest at redshifts around
2. The rest frame 1-50keV continua have photon indices with a mean of 1.64 and
a standard deviation of 0.11. Variability appears to be common on timescales
from a few months to years in the quasar rest-frame, sometimes in both fluxes
and spectral slopes.


title:
Intermediate-term periodicities in soft X-ray flare index during solar
  cycles 21, 22 and 23

abstract:
  We have analyzed the intermediate term periodicities in soft X-ray flare
index ($FI_{SXR}$) during solar cycles 21, 22 and 23. Power spectral analysis
of daily $FI_{SXR}$ reveals a significant period of 161 days in cycle 21 which
is absent during cycle 22 and 23. We have found that in cycle 22 periodicities
of 74 and 83 days are in operation. A 123 day periodicity has been found to be
statistically significant during the part of the current solar cycle 23. The
existence of these periodicities has been discussed in the light of earlier
results.


title: Self-Similar Solutions for ADAF with Toroidal Magnetic Fields

abstract:
  We examined the effect of toroidal magnetic fields on a viscous gaseous disk
around a central object under an advection dominated stage. We found
self-similar solutions for radial infall velocity, rotation velocity, sound
speed, with additional parameter $\beta$ [$=c_{\rm A}^2/(2c_{\rm s}^2)$], where
$c_{\rm A}$ is the Alfv\'en speed and $c_{\rm s}$ is the isothermal sound
speed. Compared with the non-magnetic case, in general the disk becomes thick
due to the magnetic pressure, and the radial infall velocity and rotation
velocity become fast. In a particular case, where the magnetic field is
dominant, on the other hand, the disk becomes to be magnetically supported, and
the nature of the disk is significantly different from that of the weakly
magnetized case.


title: Quasi-Periodic Oscillations from Magnetorotational Turbulence

abstract:
  Quasi-periodic oscillations (QPOs) in the X-ray lightcurves of accreting
neutron star and black hole binaries have been widely interpreted as being due
to standing wave modes in accretion disks. These disks are thought to be highly
turbulent due to the magnetorotational instability (MRI). We study wave
excitation by MRI turbulence in the shearing box geometry. We demonstrate that
axisymmetric sound waves and radial epicyclic motions driven by MRI turbulence
give rise to narrow, distinct peaks in the temporal power spectrum. Inertial
waves, on the other hand, do not give rise to distinct peaks which rise
significantly above the continuum noise spectrum set by MRI turbulence, even
when the fluid motions are projected onto the eigenfunctions of the modes. This
is a serious problem for QPO models based on inertial waves.


title: The shape of high order correlation functions in CMB anisotropy maps

abstract:
  We present a phenomenological investigation of non-Gaussian effects that
could be seen on CMB temperature maps. Explicit expressions for the temperature
correlation functions are given for different types of primordial mode
couplings. We argue that a simplified description of the radial transfer
function for the temperature anisotropies allows to get insights into the
general properties of the bi and tri-spectra. The accuracy of these results is
explored together with the use of the small scale approximation to get explicit
expressions of high order spectra. The bi-spectrum is found to have alternate
signs for the successive acoustic peaks. Sign patterns for the trispectra are
more complicated and depend specifically on the type of metric couplings. Local
primordial couplings are found to give patterns that are different from those
expected from weak lensing effects.


title: Do the Solitary Cooled-Down Neutron Stars Spontaneously Disintegrate?

abstract:
  We discuss the possibility for a cooled down and otherwise stable solitary
neutron star to make a spontaneous transition to its potential black hole
ground state. This fundamental process would mimic a precursorless explosion in
which the emitted radiations consisting of the statistical mass spectrum of
high-energy neutron-rich nuclei, gamma rays and (anti) neutrinos, would carry
away some mass of the star, leaving behind the core of the star in the form of
a black hole.


title: A Catalog and Atlas of Cataclysmic Variables: The Final Edition

abstract:
  The Catalog and Atlas of Cataclysmic Variables has been a staple of the CV
community for over 10 years. The catalog has grown from 751 CVs in 1993 to 1600
CVs at present. The catalog became a ``living'' edition in 2001, and its
contents have been continually updated since that time. Effective 27 January
2006, the catalog will transition to an archival site, with no further updates
to its contents. While it is antipicated that the site will remain active, we
present the complete contents of the site as a precaution against a loss of the
on-line data.


title: Modeling beta Virginis using seismological data

abstract:
  This paper presents the modeling of the F9 V star beta Virginis based on
seismological measurements. Using the Geneva evolution code including rotation
and atomic diffusion, we find that two distinct solutions reproduce all
existing asteroseismic and non-asteroseismic observational constraints well: a
main-sequence model with a mass of 1.28 +- 0.03 Msun and an age t = 3.24 +-
0.20 Gyr, or a model in the post-main sequence phase of evolution with a lower
mass of 1.21 +- 0.02 Msun and an age t = 4.01 +- 0.30 Gyr. The small spacings
and the ratio between small and large spacings are sensitive to the differences
in the structure of the central layers between these two solutions and are also
sensitive to the structural changes due to the rotational mixing. They can
therefore be used to unambiguously determine the evolutionary state of beta Vir
and to study the effects of rotation on the inner structure of the star.
Unfortunately, existing asteroseismic data do not enable such precise
determination. We also show that the scatter in frequencies introduced by the
rotational splittings can account for the larger dispersion of the observed
large spacings for the non-radial modes than for the radial modes.


title: Issues in the Philosophy of Cosmology

abstract:
  After a survey of the present state of cosmological theory and observations,
this article discusses a series of major themes underlying the relation of
philosophy to cosmology. These are: A: The uniqueness of the universe; B: The
large scale of the universe in space and time; C: The unbound energies in the
early universe; D: Explaining the universe -- the question of origins; E: The
universe as the background for existence; F: The explicit philosophical basis;
G: The Anthropic question: fine tuning for life; H: The possible existence of
multiverses; I: The natures of existence. Each of these themes is explored and
related to a series of Theses that set out the major issues confronting
cosmology in relation to philosophy.


title:
Properties of localized protons in neutron star matter for realistic
  nuclear models

abstract:
  We study the localization of protons in the core of neutron stars for ten
realistic nuclear models that share a common behaviour of nuclear symmetry
energy which saturates and eventually decreases at high densities. This results
in the low proton fraction of beta-stable neutron star matter. Protons form a
small admixture in the neutron star core, which is localized at sufficiently
high densities. For every model we calculate the density $n_{loc}$ above which
the localization effect is present. Our results indicate that localization
occurs at densities above $0.5-1.0 fm^{-3}$. The phase with localized protons
occupies a spherical shell or a core region inside neutron stars which contains
significant fraction of all nucleons. Proton localization is of great
importance for astrophysical properties of neutron stars as it strongly affects
transport coefficients of neutron star matter and can produce spontaneous
magnetization in neutron stars.


title: Temperature-dependent pulsations of superfluid neutron stars

abstract:
  We examine radial oscillations of superfluid neutron stars at finite internal
temperatures. For this purpose we generalize the description of relativistic
superfluid hydrodynamics to the case of superfluid mixtures. We show that in a
neutron star at hydrostatic and beta-equilibrium the red-shifted temperature
gradient is smoothed out by neutron superfluidity (but not by proton
superfluidity). We calculate radial oscillation modes of neutron stars assuming
"frozen" nuclear composition in the pulsating matter. The resulting pulsation
frequencies show a strong temperature dependence in the temperature range
(0.1-1) T_cn, where T_cn is the critical temperature of neutron superfluidity.
Combining our results with thermal evolution, we obtain a significant evolution
of the pulsation spectrum, associated with highly efficient Cooper pairing
neutrino emission, for 20 years after superfluidity onset.


title: The large scale clustering of radio sources

abstract:
  The observed two-point angular correlation function, w(theta), of mJy radio
sources exhibits the puzzling feature of a power-law behaviour up to very large
(almost 10 degrees) angular scales which cannot be accounted for in the
standard hierarchical clustering scenario for any realistic redshift
distribution of such sources. After having discarded the possibility that the
signal can be explained by a high density local source population, we find no
alternatives to assuming that - at variance with all the other extragalactic
populations studied so far, and in particular with optically selected quasars -
radio sources responsible for the large-scale clustering signal were
increasingly less clustered with increasing look-back time, up to at least z=1.
The data are accurately accounted for in terms of a bias function which
decreases with increasing redshift, mirroring the evolution with cosmic time of
the characteristic halo mass, M_{star}, entering the non linear regime. In the
framework of the `concordance cosmology', the effective halo mass controlling
the bias parameter is found to decrease from about 10^{15} M_{sun}/h at z=0 to
the value appropriate for optically selected quasars, 10^{13} M_{sun}/h, at
z=1.5. This suggests that, in the redshift range probed by the data, the
clustering evolution of radio sources is ruled by the growth of large-scale
structure, and that they are associated with the densest environments
virializing at any cosmic epoch. The data provide only loose constraints on
radio source clustering at z>1 so we cannot rule out the possibility that at
these redshifts the clustering evolution of radio sources enters a different
regime, perhaps similar to that found for optically selected quasars. The
dependence of w(theta) on cosmological parameters is also discussed.


title: Extending the Sensitivity of Air Cerenkov Telescopes

abstract:
  Over the last decade, the Imaging Air Cerenkov technique has proven itself to
be an extremely powerful means to study very energetic gamma-radiation from a
number of astrophysical sources in a regime which is not practically accessible
to satellite-based instruments. The further development of this approach in
recent years has generally concentrated on increasing the density of camera
pixels, increasing the mirror area and using multiple telescopes. Here we
present a practical method to substantially improve the sensitivity of
Atmospheric Cerenkov Telescopes using wide-field cameras with a relatively
course density of photomultiplier tubes. The 2-telescope design considered here
is predicted to be more than ~3 times more sensitive than existing/planned
arrays in the regime above 300 GeV for continuously emitting sources; up to ~10
times more sensitive for hour-scale emission (relevant for episodic sources,
such as AGN); significantly more sensitive in the regime above 10 TeV; and
possessing a sky coverage which is roughly an order of magnitude larger than
existing instruments. It should be possible to extend this approach for even
further improvement in sensitivity and sky coverage.


title: Non-gaussianity and cosmic uncertainty in curvaton-type models

abstract:
  In curvaton-type models, observable non-gaussianity of the curvature
perturbation would come from a contribution of the form $(\delta\sigma)^2$,
where $\delta\sigma$ is gaussian. I analyse this situation allowing
$\delta\sigma$ to be scale-dependent. The actual curvaton model is considered
in more detail than before, including its cosmic uncertainty and anthropic
status. The status of curvaton-type models after WMAP year three data is
considered.


title:
Estimating Column Density in Molecular Clouds with FIR and Sub-mm
  Emission Maps

abstract:
  We have used a numerical simulation of a turbulent cloud to synthesize maps
of the thermal emission from dust at a variety of far-IR and sub-mm
wavelengths. The average column density and external radiation field in the
simulation is well matched to clouds such as Perseus and Ophiuchus. We use
pairs of single-wavelength emission maps to derive the dust color temperature
and column density, and we compare the derived column densities with the true
column density. We demonstrate that longer wavelength emission maps yield less
biased estimates of column density than maps made towards the peak of the dust
emission spectrum. We compare the scatter in the derived column density with
the observed scatter in Perseus and Ophiuchus. We find that while in Perseus
all of the observed scatter in the emission-derived versus the
extinction-derived column density can be attributed to the flawed assumption of
isothermal dust along each line of sight, in Ophiuchus there is additional
scatter above what can be explained by the isothermal assumption. Our results
imply that variations in dust emission properties within a molecular cloud are
not necessarily a major source of uncertainty in column density measurements.


title: PKS 1018-42: A Powerful Kinetically Dominated Quasar

abstract:
  We have identified PKS 1018-42 as a radio galaxy with extraordinarily
powerful jets, over twice as powerful as any 3CR source of equal or lesser
redshift except for one (3C196). It is perhaps the most intrinsically powerful
extragalactic radio source in the, still poorly explored, Southern Hemisphere.
PKS 1018-42 belongs to the class of FR II objects that are kinetically
dominated, the jet kinetic luminosity, $Q \sim 6.5 \times
10^{46}\mathrm{ergs/s}$ (calculated at 151 MHz), is 3.4 times larger than the
total thermal luminosity (IR to X-ray) of the accretion flow, $L_{bol} \sim 1.9
\times 10^{46}\mathrm{ergs/s}$. It is the fourth most kinetically dominated
quasar that we could verify from existing radio data. From a review of the
literature, we find that kinetically dominated sources such as PKS 1018-42 are
rare, and list the 5 most kinetically dominated sources found from our review.
Our results for PKS 1018-42 are based on new observations from the Australia
Telescope Compact Array.


title:
The K luminosity-metallicity relation for dwarf galaxies and the tidal
  dwarf galaxies in the tails of HCG 31

abstract:
  We determine a K-band luminosity-metallicity (K-Z) relation for dwarf
irregular galaxies, over a large range of magnitudes, -20.5 < M_K < -13.5,
using a combination of K photometry from either the 2-micron all sky survey
(2MASS) or the recent study of Vadivescu er al. (2005), and metallicities
derived mainly with the T_e method, from several different studies. We then use
this newly-derived relation, together with published K_s photometry and our new
spectra of objects in the field of HCG 31 to discuss the nature of the possible
tidal dwarf galaxies of this group. We catalogue a new member of HCG 31, namely
"R", situated ~40 kpc north of the group center, composed by a ring of H alpha
knots which coincides with a peak in HI. This object is a deviant point in the
K-Z relation (it has too high metallicity for its luminosity) and its projected
distance to the parent galaxy and large gas reservoir makes it one of the most
promising tidal dwarf galaxy candidates of HCG 31, together with object F. The
subsystems A1, E, F, H and R all have metallicities similar to that of the
galaxies A+C and B, result that is expected in a scenario where those were
formed from material expelled from the central galaxies of HCG 31. While
objects A1, E and H will most probably fall back onto their progenitors, F and
R may survive as tidal dwarf galaxies. We find that two galaxies of HCG 31, G
and Q, have A+em spectral signatures, and are probably evolving toward a
post-starburst phase.


title:
Contribution of Stellar Tidal Disruptions to the X-Ray Luminosity
  Function of Active Galaxies

abstract:
  The luminosity function of active galactic nuclei has been measured down to
luminosities ~10^{42} erg/s in the soft and hard X-rays. Some fraction of this
activity is associated with the accretion of the material liberated by the
tidal disruption of stars by massive black holes. We estimate the contribution
to the X-ray luminosity function from the tidal disruption process. While the
contribution depends on a number poorly known parameters, it appears that it
can account for the majority of X-ray selected AGN with soft or hard X-ray
luminosities <~10^{43}-10^{44} erg/s. If this is correct, a picture emerges in
which a significant portion of the X-ray luminosity function of AGN is
comprised of sources powered by tidal-disruption at the faint end, while the
sources at the bright end are powered by non-stellar accretion. Black holes
with masses <~2x10^6 Msun could have acquired most of their present mass by an
accretion of tidal debris. In view of the considerable theoretical uncertainty
concerning the detailed shape of the light curves of tidal disruption events,
we focus on power-law luminosity decay (as identified in candidate tidal
disruption events), but we also discuss constant accretion rate models.


title:
The Relation Between Quasar and Merging Galaxy Luminosity Functions and
  the Merger-Induced Star Formation Rate of the Universe

abstract:
  Using a model for self-regulated growth of black holes (BHs) in mergers
involving gas-rich galaxies, we study the relationship between quasars and the
population of merging galaxies and predict the merger-induced star formation
rate density of the Universe. Mergers drive nuclear gas inflows, fueling
starbursts and 'buried quasars' until accretion feedback expels the gas,
rendering a briefly visible optical quasar. Star formation is shut down and
accretion declines, leaving a passively evolving remnant with properties
typical of red, elliptical galaxies. Based on evolution of these events in our
simulations, we demonstrate that the observed statistics of merger rates,
luminosity functions (LFs) and mass functions, SFR distributions, specific
SFRs, quasar and quasar host galaxy LFs, and elliptical/red galaxy LFs are
self-consistent and follow from one another as predicted by the merger
hypothesis. We use our simulations to de-convolve both quasar and merging
galaxy LFs to determine the birthrate of black holes of a given final mass and
merger rates as a function of stellar mass. We use this to predict the merging
galaxy LF in several observed wavebands, color-magnitude relations, mass
functions, absolute and specific SFR distributions and SFR density, and quasar
host galaxy LFs, as a function of redshift from z=0-6. We invert this and
predict e.g. quasar LFs from observed merger LFs or SFR distributions. Our
results agree well with observations, but idealized models of quasar
lightcurves are ruled out by comparison of merger and quasar observations at
>99.9% confidence. Using only observations of quasars, we estimate the
contribution of mergers to the SFR density of the Universe even to high
redshifts z~4.


title: Gaseous Planets, Protostars And Young Brown Dwarfs : Birth And Fate

abstract:
  We review recent theoretical progress aimed at understanding the formation
and the early stages of evolution of giant planets, low-mass stars and brown
dwarfs. Calculations coupling giant planet formation, within a modern version
of the core accretion model, and subsequent evolution yield consistent
determinations of the planet structure and evolution. Because of the
uncertainties in the initial conditions, however, it is not possible to say
whether young planets are faint or bright compared with low-mass young brown
dwarfs. We review the effects of irradiation and evaporation on the evolution
of short period planets and argue that substantial mass loss may have occurred
for these objects. Concerning star formation, geometrical effects in protostar
core collapse are examined by comparing 1D and 3D calculations. Spherical
collapse is shown to overestimate the core inner density and temperature and
thus to yield incorrect initial conditions for PMS or young brown dwarf
evolution. Accretion is also shown to occur over a very limited fraction of the
protostar surface. Accretion affects the evolution of young brown dwarfs and
yields more compact structures for a given mass and age, thus fainter
luminosities. This can lead to severe misinterpretations of the mass and/or age
of young accreting objects from their location in the HR diagram. We argue that
newborn stars and brown dwarfs should appear rapidly over an extended area in
the HR diagram, depending on their accretion history, rather than on a well
defined birth line. Finally, we suggest that the distinction between planets
and brown dwarfs be based on an observational diagnostic, reflecting the
different formation mechanisms between these two distinct populations, rather
than on an arbitrary, confusing definition.


title:
HST/ACS Multiband Coronagraphic Imaging of the Debris Disk around Beta
  Pictoris

abstract:
  (Abridged.) We present F435W (B), F606W (Broad V), and F814W (Broad I)
coronagraphic images of the debris disk around Beta Pictoris obtained with
HST's Advanced Camera for Surveys. We confirm that the previously reported warp
in the inner disk is a distinct secondary disk inclined by ~5 deg from the main
disk. The main disk's northeast extension is linear from 80 to 250 AU, but the
southwest extension is distinctly bowed with an amplitude of ~1 AU over the
same region. Both extensions of the secondary disk appear linear, but not
collinear, from 80 to 150 AU. Within ~120 AU of the star, the main disk is ~50%
thinner than previously reported. The surface-brightness profiles along the
spine of the main disk are fitted with four distinct radial power laws between
40 and 250 AU, while those of the secondary disk between 80 and 150 AU are
fitted with single power laws. These discrepancies suggest that the two disks
have different grain compositions or size distributions. The F606W/F435W and
F814W/F435W flux ratios of the composite disk are nonuniform and asymmetric
about both projected axes of the disk. Within ~120 AU, the m_F435W-m_F606W and
m_F435W-m_F814W colors along the spine of the main disk are ~10% and ~20%
redder, respectively, than those of Beta Pic. These colors increasingly redden
beyond ~120 AU, becoming 25% and 40% redder, respectively, than the star at 250
AU. We compare the observed red colors within ~120 AU with the simulated colors
of non-icy grains having a radial number density ~r^-3 and different
compositions, porosities, and minimum grain sizes. The observed colors are
consistent with those of compact or moderately porous grains of astronomical
silicate and/or graphite with sizes >0.15-0.20 um, but the colors are
inconsistent with the blue colors expected from grains with porosities >90%.


title: Ca II H and K Chromospheric Emission Lines in Late K and M Dwarfs

abstract:
  We have measured the profiles of the Ca II H and K chromospheric emission
lines in 147 main sequence stars of spectral type M5-K7 (0.30-0.55 solar
masses) using multiple high resolution spectra obtained during six years with
the HIRES spectrometer on the Keck 1 telescope. Remarkably, the average FWHM,
equivalent widths, and line luminosities of Ca II H and K increase by a factor
of 3 with increasing stellar mass over this small range of stellar masses. We
fit the H and K lines with a double Gaussian model to represent both the
chromospheric emission and the non-LTE central absorption. Most of the sample
stars display a central absorption that is typically redshifted by ~0.1 km/s
relative to the emission, but the nature of this velocity gradient remains
unknown. The FWHM of the H and K lines increase with stellar luminosity,
reminiscent of the Wilson-Bappu effect in FGK-type stars. Both the equivalent
widths and FWHM exhibit modest temporal variability in individual stars. At a
given value of M_v, stars exhibit a spread in both the equivalent width and
FWHM of Ca II H and K, due both to a spread in fundamental stellar parameters
including rotation rate, age, and possibly metallicity, and to the spread in
stellar mass at a given M_v. The K line is consistently wider than the H line,
as expected, and its central absorption is more redshifted, indicating that the
H and K lines form at slightly different heights in the chromosphere where the
velocities are slightly different. The equivalent width of H-alpha correlates
with Ca II H and K only for stars having Ca II equivalent widths above ~2
angstroms, suggesting the existence of a magnetic threshold above which the
lower and upper chromospheres become thermally coupled.


title:
Millimetre Continuum Observations of Southern Massive Star Formation
  Regions II. SCUBA observations of cold cores and the dust grain emissivity
  index $\beta$

abstract:
  We report the results of a submillimetre continuum emission survey targeted
toward 78 star formation regions, 72 of which are devoid of methanol maser and
UC HII regions, identified in the SEST/SIMBA millimetre continuum survey of
Hill et al. (2005). At least 45 per cent of the latter sources, dubbed
`mm-only', detected in this survey are also devoid of mid infrared MSX,
emission. The 450 and 850micron, continuum emission was mapped using the
Submillimetre Common User Bolometer Array (SCUBA) instrument on the James Clerk
Maxwell Telescope (JCMT). Emission is detected toward 97 per cent of the 78
sources targeted as well as towards 28 other SIMBA sources lying in the SCUBA
fields.
  We concatenate the results from four (sub)millimetre continuum surveys of
massive star formation [Walsh et al. (2003), Hill et al. (2005), Thompson et
al. (2006); as well as this work], together with the Galactic Plane map of
Pierce-Price et al. (2000) in order to determine the dust grain emissivity
index $\beta$ for each of the sources in the SIMBA source list. We examine the
value of $\beta$ with respect to temperature, as well as for the source classes
identified in the SIMBA survey, for variation of this index. Our results
indicate that $\beta$ is typically 2, which is consistent with previous
determinations in the literature, but for a considerably larger sample than
previous work.


title:
Anisotropic weak turbulence of Alfven waves in collisionless
  astrophysical plasmas

abstract:
  The evolution of Alfven turbulence due to three-wave interactions is
discussed using kinetic theory for a collisionless, thermal plasma. There are
three low-frequency modes, analogous to the three modes of compressible MHD.
When only Alfven waves are considered, the known anisotropy of turbulence in
incompressible MHD theory is reproduced. Inclusion of a fast mode wave leads to
separation of turbulence into two regimes: small wave numbers where three-wave
processes involving a fast mode is dominant, and large wave numbers where the
three Alfven wave process is dominant. Possible application of the anisotropic
Alfven turbulence to the interstellar medium and dissipation of magnetic energy
in magnetars is discussed.


title: 511 keV line and diffuse gamma rays from moduli

abstract:
  We obtain the spectrum of gamma ray emissions from the moduli whose decay
into $e^+ e^-$ accounts for the 511 keV line observed by SPI/INTERGRAL. The
moduli emit gamma rays through internal bremsstrahlung, and also decay directly
into two gammas via tree and/or one-loop diagrams. We show that the internal
bremsstahlung constrains the mass of the moduli below $\sim 40$ MeV
model-independently. On the other hand, the flux of two gammas directly decayed
from the moduli through one loop diagrams will exceed the observed galactic
diffuse gamma-ray background if the moduli mass exceeds $\sim 20$ MeV in the
typical situation. Moreover, forthcoming analysis of SPI data in the range of
1-8 MeV may detect the line emisson with the energy half the moduli mass in the
near future, which confirms the decaying moduli scenario.


title:
The ACS Virgo Cluster Survey. VI. Isophotal Analysis and the Structure
  of Early-Type Galaxies

abstract:
  (Abridged) We present a detailed analysis of the morphology, isophotal
parameters and surface brightness profiles for 100 early-type members of the
Virgo Cluster, from dwarfs (M_B = -15.1 mag) to giants (M_B = -21.8 mag). Each
galaxy has been imaged in two filters, closely resembling the Sloan g and z
passbands, using the Advanced Camera for Surveys on board the Hubble Space
Telescope.
  Dust and complex morphological structures are common, with kiloparsec-scale
stellar disks, bars, and nuclear stellar disks seen in 60% of galaxies with
intermediate luminosity (-20 < M_B < -17), and dust seen in 42% of galaxies
brighter than M_B = -18.9 mag. Dust morphologies range from faint wisps and
patches on tens of parsec scales, to regular, highly organized kpc-scale dust
disks, often showing evidence of recent star formation.
  Surface brightness profiles and isophotal parameters are derived typically
within 8 kpc from the center for the brightest galaxies, and 1.5 kpc for the
faintest systems, with a resolution (FWHM) of 7 pc. Based on a parametrization
of the surface brightness profiles in terms of a Sersic or core-Sersic model,
we find that 1) there is no evidence of a bimodal behavior of the slope, gamma,
of the profile in the innermost regions; 2) although the brightest galaxies
have shallow inner profiles, the shallowest profiles (lowest gamma values) are
found in faint dwarf systems; 3) the widely adopted separation of early-type
galaxies between "core" and "power-law" types, which had originally been
prompted by the claim of a clear bimodal distribution of gamma values, is
untenable; and 4) there is no evidence of a structural dichothomy between dwarf
and regular ellipticals.


title:
A Large-Area Search for Low Mass Objects in Upper Scorpius I: The
  Photometric Campaign and New Brown Dwarfs

abstract:
  We present a wide-field photometric survey covering ~200 deg^2 toward the
Upper Scorpius OB association. Data taken in the R and I bands with the Quest-2
camera on the Palomar 48-inch telescope were combined with the 2MASS JHK survey
and used to select candidate pre-main sequence stars. Follow-up spectroscopy
with the Palomar 200-inch telescope of 62 candidate late-type members
identified 43 stars that have surface gravity signatures consistent with
association membership. From the optical/near-infrared photometry and derived
spectral types we construct an HR diagram for the new members and find 30
likely new brown dwarfs, nearly doubling the known substellar population of the
Upper Scorpius OB association. Continuation of our spectroscopic campaign
should reveal hundreds on new stellar and substellar members.


title: The GZK Bound in Discrete Space

abstract:
  The maximum distance bound for ultrahigh energy cosmic rays (UHECR) with
energies above the Greisen-Zatsepin-Kuzmich cutoff $\sim 10^{19} eV$ relaxes
significantly if there is some mechanism that forces UHECR to propagate in
discrete intervals, rather than continuously, through intergalactic space. In
particular, intervals as small as a femtometer relax the bound for protons by
an order of magnitude and potentially account for the observed excess of UHECR
flux.


title: Starbursts and AGN Fueling through Secular Evolution

abstract:
  Except in the most extreme cases of nuclear activity, either starbursts or
AGN, it is difficult to find observationnally a close link between the dynamics
and the activity. Theoretically however, the necessary step to fuel the gas to
the center, is that gravity torques are created through a non-axisymmetric
pattern, either bar and/or spiral, triggered or not by a tidal interaction.
  We describe the sequence of processes for a typical evolution cycle for a
spiral galaxy, and the possible efficient feedback mechanisms. The various
morphologies and dynamical states of spiral galaxies are interpreted in terms
of a sequence of evolutionary phases, and the corresponding time-scales can be
estimated from observations. In this scenario, activity in galaxies is related
to the appearance of bar instability, although they might not be synchronised
in phase. The role of external gas accretion in the secular evolution is
discussed.


title: Contribution of a nearby Pulsar to Cosmic Rays observed at Earth

abstract:
  Contribution of nearby pulsars to the cosmic rays observed at Earth has been
studied. It is found that the experimental bound on amplitude of cosmic ray
anisotropy may produce significant constraint on the efficiency of converting
pulsar rotational energy to emitted particles kinetic energy. Cosmic ray fluxes
from two well known nearby gamma ray pulsars, namely the Vela and Geminga
pulsars, are estimated. The analysis suggests that observed bound on cosmic ray
anisotropy restricts the contributions of the Vela and the Geminga pulsars to
at most 1 % of the observed cosmic rays below the knee.


title: RHESSI observation of flare elements

abstract:
  RHESSI observations of elementary flare bursts are presented. These solar
flare elements are distinct emission peaks of a duration of some tens of
seconds present in the hard X-ray light curves. They are characterized by
consistent soft-hard-soft spectral behavior, which can be described in a
quantitative way and compared which predictions from acceleration models. A
detailed analysis of hard X-ray images for an M5 class flare shows that
elementary flare bursts do not occur at distinct locations, but as twin X-ray
sources move smoothly along an arcade of magnetic loops. This observation
apparently contradicts the predictions of standard translation invariant
2.5-dimensional reconnection models.


title:
VLT/UVES constraints on the carbon isotope ratio 12C/13C at z=1.15
  toward the quasar HE 0515-4414

abstract:
  We analyzed the CI lines associated with the damped Ly-alpha system observed
at zabs = 1.15 in the spectrum of HE 0515-4414 to derive the 12C/13C ratio. The
spectrum was obtained by means of the UV-Visual Echelle Spectrograph (UVES) at
the ESO Very Large Telescope (VLT). The obtained lower limit 12C/13C > 80
(2sigma C.L.) shows for the first time that the abundance of 13C in the
extragalactic intervening clouds is very low. This rules out a significant
contribution from intermediate-mass stars to the chemical evolution of matter
sampled by this line of sight. The estimated low amount of 13C is in agreement
with low abundances of nitrogen observed in damped Ly-alpha systems - the
element produced in the same nuclear cycles and from about the same stars as
13C.


title:
An INTEGRAL/IBIS view of Young Galactic SNRs through the 44Ti gamma-ray
  lines

abstract:
  We present preliminary results of INTEGRAL/IBIS observations on Cas A, Tycho
and Vela Junior Supernova remnants in the line emission of 44Ti. This
radioactive nucleus is thought to be exclusively produced in supernovae during
the first stages of the explosion. It has a lifetime of about 87 y and is then
the best indicator of young SNRs, as exemplified by the detection of 44Ti in
the youngest known Galactic SNR Cas A with GRO/COMPTEL and latter with
BeppoSAX. In this paper, we will focus on this SNR for which we confirm the
detection of 44Ti and point out the importance to know the nature of the hard
X-ray continuum, the Tycho SNR, for which no indication of 44Ti was ever
reported, and Vela Junior, for which the claimed detection of 44Ti with COMPTEL
is still controversial. The INTEGRAL/IBIS observations bring new constraints on
the nature of these SNRs and on the nucleosynthesis which took place during the
explosions.


title:
On the magnetic structure and wind parameter profiles of Alfven wave
  driven winds in late-type supergiant stars

abstract:
  Cool stars at giant and supergiant evolutionary phases present low velocity
and high density winds, responsible for the observed high mass-loss rates.
Although presenting high luminosities, radiation pressure on dust particles is
not sufficient to explain the wind acceleration process. Among the possible
solutions to this still unsolved problem, Alfven waves are, probably, the most
interesting for their high efficiency in transfering energy and momentum to the
wind. Typically, models of Alfven wave driven winds result in high velocity
winds if they are not highly damped. In this work we determine
self-consistently the magnetic field geometry and solve the momentum, energy
and mass conservation equations, to demonstrate that even a low damped Alfven
wave flux is able to reproduce the low velocity wind. We show that the magnetic
fluxtubes expand with a super-radial factor S>30 near the stellar surface,
larger than that used in previous semi-empirical models. The rapid expansion
results in a strong spatial dilution of the wave flux. We obtained the wind
parameter profiles for a typical supergiant star of 16 M_sun. The wind is
accelerated in a narrow region, coincident with the region of high divergence
of the magnetic field lines, up to 100 km/s. For the temperature, we obtained a
slight decrease near the surface for low damped waves, because the wave heating
mechanism is less effective than the radiative losses. The peak temperature
occurs at 1.5 r_0 reaching 6000 K. Propagating outwards, the wind cools down
mainly due to adiabatic expansion.


title: The evolution of misaligned accretion discs and spinning black holes

abstract:
  In this paper we consider the process of alignment of a spinning black hole
and a surrounding misaligned accretion disc. We use a simplified set of
equations, that describe the evolution of the system in the case where the
propagation of warping disturbances in the accretion disc occurs diffusively, a
situation likely to be common in the thin discs in Active Galactic Nuclei
(AGN). We also allow the direction of the hole spin to move under the action of
the disc torques. In such a way, the evolution of the hole-disc system is
computed self-consistently. We consider a number of different situations and we
explore the relevant parameter range, by varying the location of the warp
radius $R_{\rm w}$ and the propagation speed of the warp. We find that the
dissipation associated with the twisting of the disc results in a large
increase in the accretion rate through the disc, so that AGN accreting from a
misaligned disc are likely to be significantly more luminous than those
accreting from a flat disc. We compute explicitly the time-scales for the
warping of the disc and for the alignment process and compare our results with
earlier estimates based on simplified steady-state solutions. We also confirm
earlier predictions that, under appropriate circumstances, accretion can
proceed in a counter-aligned fashion, so that the accreted material will
spin-down the hole, rather than spinning it up. Our results have implication in
a number of different observational features of AGN such as the orientation and
shape of jets, the shape of X-ray iron lines, and the possibility of
obscuration and absorption of X-ray by the outer disc as well as the general
issue of the spin history of black holes during their growth.


title: A transient relativistic radio jet from Cygnus X-1

abstract:
  We report the first observation of a transient relativistic jet from the
canonical black hole candidate, Cygnus X-1, obtained with the Multi-Element
Radio-Linked Interferometer Network (MERLIN). The jet was observed in only one
of six epochs of MERLIN imaging of the source during a phase of repeated X-ray
spectral transitions in 2004 Jan--Feb, and this epoch corresponded to the
softest 1.5-12 keV X-ray spectrum. With only a single epoch revealing the jet,
we cannot formally constrain its velocity. Nevertheless, several lines of
reasoning suggest that the jet was probably launched 0.5-4.0 days before this
brightening, corresponding to projected velocities of 0.2c < v_app < 1.6c, and
an intrinsic velocity of > 0.3c. We also report the occurrence of a major radio
flare from Cyg X-1, reaching a flux density of ~120 mJy at 15 GHz, and yet not
associated with any resolvable radio emission, despite a concerted effort with
MERLIN. We discuss the resolved jet in terms of the recently proposed 'unified
model' for the disc-jet coupling in black hole X-ray binaries, and tentatively
identify the 'jet line' for Cyg X-1. The source is consistent with the model in
the sense that a steady jet appears to persist initially when the X-ray
spectrum starts softening, and that once the spectral softening is complete the
core radio emission is suppressed and transient ejecta / shock observed.
However, there are some anomalies, and Cyg X-1 clearly does not behave like a
normal black hole transient in progressing to the canonical soft / thermal
state once the ejection event has happened.


title:
Cosmic Rays X. The cosmic ray knee and beyond: Diffusive acceleration at
  oblique shocks

abstract:
  Our purpose is to evaluate the rate of the maximum energy and the
acceleration rate that cosmic rays acquire in the non-relativistic diffusive
shock acceleration as it could apply during their lifetime in various
astrophysical sites, where highly oblique shocks exist. We examine numerically
(using Monte Carlo simulations) the effect of the diffusion coefficients on the
energy gain and the acceleration rate, by testing the role between the
obliquity of the magnetic field to the shock normal, and the significance of
both perpendicular cross-field diffusion and parallel diffusion coefficients to
the acceleration rate. We find (and justify previous analytical work - Jokipii
1987) that in highly oblique shocks the smaller the perpendicular diffusion
gets compared to the parallel diffusion coefficient values, the greater the
energy gain of the cosmic rays to be obtained. An explanation of the cosmic ray
spectrum in high energies, between $10^{15}$eV and about $10^{18}$eV is
claimed, as we estimate the upper limit of energy that cosmic rays could gain
in plausible astrophysical regimes; interpreted by the scenario of cosmic rays
which are injected by three different kind of sources, (a) supernovae which
explode into the interstellar medium, (b) Red Supergiants, and (c) Wolf-Rayet
stars, where the two latter explode into their pre-supernovae winds.


title:
Multi wavelength study of the gravitational lens system RXS J1131-1231:
  II Lens model and source reconstruction

abstract:
  High angular resolution images of the complex gravitational lens system RXS
J1131-1231 (a quadruply imaged AGN with a bright Einstein ring) obtained with
the Advanced Camera for Surveys and NICMOS instruments onboard the Hubble Space
Telescope are analysed to determine the lens model and to reconstruct the host
galaxy.
  Results: 1- Precise astrometry and photometry of the four QSO lensed images
(A-D) and of the lensing galaxy (G) are obtained. They are found in agreement
with an independent study presented in a companion paper. The position and
colours of the X object seen in projection close to the lens are found to be
only compatible with a satellite galaxy associated with the lens.
  2- The Singular Isothermal Ellipsoid plus external shear provides a good fit
of the astrometry of images A-D. The positions of extended substructures are
also well reproduced. However an octupole (m=4) must be added to the lens
potential in order to reproduce the observed lens position, as well as the
IB/IC point-like image flux ratio. The ellipticity and orientation of the mass
quadrupole are found similar to those of the light distribution, fitted by a
Sersic profile. The lens (z=0.295) is found to be a massive elliptical in a
rich environment and showing possible evolution with respect to z=0.
  3- The host galaxy (z=0.658) is found to be a substantially magnified (M ~ 9)
luminous Seyfert 1 spiral galaxy. The angular resolution is sufficient to see
regions where stars are intensively forming. Interaction with a closeby
companion is also observed.
  4- Finally, in the case of RXS J1131-1231, extended lensed structures do not
help much in constraining the lens model.


title: The growth of the nuclear black holes in submillimeter galaxies

abstract:
  We show that the ABC scenario we proposed for the co-evolution of spheroids
and QSOs predicts accretion rates and masses of supermassive black holes in
sub-mm galaxies in keeping with recent X-ray determinations. These masses are
well below the local values, and those predicted by alternative models. The
observed column densities may be mostly due to ISM in the galaxy. The
contribution of the associated nuclear activity to the X-ray background is
likely negligible, while they may contribute a sizeable fraction $\sim 10 %$ to
hard-X cumulative counts at the faintest observed fluxes.


title:
Cosmic evolution of metal densities: the enrichment of the
  Inter-Galactic Medium

abstract:
  By means of chemo-photometric models for galaxies of different morhological
types, we have carried out a detailed study of the history of element
production by spheroidal and dwarf irregular galaxies. Spheroidal galaxies
suffer a strong and intense star formation episode at early times. In dwarf
irregulars, the SFR proceeds at a low regime but continuously. Both galactic
types enrich the IGM with metals, by means of galactic winds. We have assumed
that the galaxy number density is fixed and normalized to the value of the
optical luminosity function observed in the local universe. Our models allow us
to investigate in detail how the metal fractions locked up in spheroid and
dwarf irregular stars, in the ISM and ejected into the IGM have changed with
cosmic time. By relaxing the instantaneous recycling approximation and taking
into account stellar lifetimes, for the first time we have studied the
evolution of the chemical abundance ratios in the IGM and compared our
predictions with a set of observations by various authors. Our results indicate
that the bulk of the IGM enrichment is due to spheroids, with dwarf irregular
galaxies playing a negligible role. Our predictions grossly account for the
[O/H] observed in the IGM at high redshift, but overestimate the [C/H].
Furthermore, it appears hard to reproduce the abundance ratios observed in the
high-redshift IGM. Some possible explanations are discussed in the text. This
is the first attempt to study the abundance ratios in the IGM by means of
detailed chemical evolution models which take into account the stellar
lifetimes. Numerical simulations adopting our chemical evolution prescriptions
could be useful to improve our understanding of the IGM chemical enrichment.


title:
An X-ray Search for Compact Central Sources in Supernova Remnants II:
  Six Large Diameter SNRs

abstract:
  We present the second in a series of results in which we have searched for
undiscovered neutron stars in supernova remnants (SNRs). This paper deals with
the largest six SNRs in our sample, too large for Chandra or XMM-Newton to
cover in a single pointing. These SNRs are nearby, with typical distances of <1
kpc. We therefore used the ROSAT Bright Source Catalog and past observations in
the literature to identify X-ray point sources in and near the SNRs. Out of 54
sources, we were immediately able to identify optical/IR counterparts to 41
from existing data. We obtained Chandra snap-shot images of the remaining 13
sources. Of these, 10 were point sources with readily identified counterparts,
two were extended, and one was not detected in the Chandra observation but is
likely a flare star. One of the extended sources may be a pulsar wind nebula,
but if so it is probably not associated with the nearby SNR. We are then left
with no identified neutron stars in these six SNRs down to luminosity limits of
\~1e32 ergs/s. These limits are generally less than the luminosities of typical
neutron stars of the same ages, but are compatible with some lower-luminosity
sources such as the neutron stars in the SNRs CTA 1 and IC 443.


title:
Dust Destruction in Type Ia Supernova Remnants in the Large Magellanic
  Cloud

abstract:
  We present first results from an extensive survey of Magellanic Clouds
supernova remnants (SNRs) with the Spitzer Space Telescope. We describe IRAC
and MIPS imaging observations at 3.6, 4.5, 5.8, 8, 24, and 70 microns of four
Balmer-dominated Type Ia SNRs in the Large Magellanic Cloud (LMC): DEM L71
(0505-67.9), 0509--67.5, 0519--69.0, and 0548-70.4. None was detected in the
four short-wavelength IRAC bands, but all four were clearly imaged at 24
microns, and two at 70 microns. A comparison of these images to Chandra
broadband X-ray images shows a clear association with the blast wave, and not
with internal X-ray emission associated with ejecta. Our observations are well
described by 1-D shock models of collisionally heated dust emission, including
grain size distributions appropriate for the LMC, grain heating by collisions
with both ions and electrons, and sputtering of small grains. Model parameters
are constrained by X-ray, optical, and far-ultraviolet observations. Our models
can reproduce observed 70/24 micron flux ratios only by including sputtering,
destroying most grains smaller than 0.03-0.04 microns in radius. We infer total
dust masses swept up by the SNR blast waves, before sputtering, of order 0.01
solar masses, several times less than those implied by a dust/gas mass ratio of
0.3 percent as often assumed for the LMC. Substantial dust destruction has
implications for gas-phase abundances.


title:
Scattering of magnetosonic waves in a relativistic and an-isotropic
  magnetised plasma

abstract:
  Gravitational waves (GW) propagating through a magnetised plasma excite
low-frequency magnetohydrodynamic (MHD) waves. In this paper we investigate
whether these waves can produce observable radio emission at higher frequencies
by scattering on an an-isotropic intrinsically relativistic distribution of
electrons and positrons in the force-free wind surrounding a double neutron
star binary merger. The relativistic particle distribution is assumed to be
strictly along the magnetic field lines, while the magneto-plasma streams out
at a relativistic speed from the neutron stars. In the case of Compton
scattering of an incident MHD wave transverse to the magnetic field, we find
that the probability of scattering to both a transverse x-mode and a
quasi-transverse Langmuir-o mode is suppressed when the scattered frequency is
below the local relativistic gyro-frequency, i.e. when the magnetic field is
very strong.


title: Quasars in the COSMOS Field

abstract:
  We obtained medium-resolution spectra of 336 quasar candidates in the COSMOS
HST/Treasury field using the MMT 6.5-meter telescope and the Hectospec
multi-object spectrograph. Candidates were drawn from the Sloan Digital Sky
Survey (SDSS) DR1 catalog using quasar flags set by the SDSS multi-color quasar
target selection algorithm. In this paper we present our discovery spectra from
1.39 square degrees (69.5% of the COSMOS field) and a discussion of the
selection method and yields. We confirmed 95 quasars, including at least 2
BALs; 80 of these are new quasars that do not appear in previous quasar
confirmation follow-up studies. The candidates additionally included 184
compact emission-line galaxies, a third of which are likely Type 2 AGN, and 12
stars. The quasars span a range in magnitude of 18.3<g<22.5 and a range in
redshift of 0.2<z<2.3. Our results are consistent with a lower limit quasar
surface density from SDSS color selection of 102 per square degree down to
g=22.5 over the entire COSMOS field. This work is the first step toward the
eventual goal of setting up a grid of quasar absorption line probes of the 2
square degree field, and of conducting a complete census of supermassive black
holes in this well-studied survey region. The total quasar count at the
conclusion of this study is 139, making COSMOS one of the most densely-sampled
regions of sky where a grid of quasar sightlines can be used to probe the
intervening volume.


title:
The Albedo, Size, and Density of Binary Kuiper Belt Object (47171) 1999
  TC36

abstract:
  We measured the system-integrated thermal emission of the binary Kuiper Belt
Object 1999 TC36 at wavelengths near 24 and 70 microns using the Spitzer space
telescope. We fit these data and the visual magnitude using both the Standard
Thermal Model and thermophysical models. We find that the effective diameter of
the binary is 405 km, with a range of 350 -- 470 km, and the effective visible
geometric albedo for the system is 0.079 with a range of 0.055 -- 0.11. The
binary orbit, magnitude contrast between the components, and system mass have
been determined from HST data (Margot et al., 2004; 2005a; 2005b). Our
effective diameter, combined with that system mass, indicate an average density
for the objects of 0.5 g/cm3, with a range 0.3 -- 0.8 g/cm3. This density is
low compared to that of materials expected to be abundant in solid bodies in
the trans-Neptunian region, requiring 50 -- 75% of the interior of 1999 TC36 be
taken up by void space. This conclusion is not greatly affected if 1999 TC36 is
``differentiated'' (in the sense of having either a rocky or just a non-porous
core). If the primary is itself a binary, the average density of that
(hypothetical) triple system would be in the range 0.4 -- 1.1 g/cm3, with a
porosity in the range 15 -- 70%.


title: The Weak Field Limit of the Magnetorotational Instability

abstract:
  We investigate the behavior of the magneto-rotational instability in the
limit of extremely weak magnetic field, i.e., as the ratio of ion cyclotron
frequency to orbital frequency (X) becomes small. Considered only in terms of
cold two-fluid theory, instability persists to arbitrarily small values of X,
and the maximum growth rate is of order the orbital frequency except for the
range m_e/m_i < |X| < 1, where it can be rather smaller. In this range, field
aligned with rotation (X > 0) produces slower growth than anti-aligned field (X
< 0). The maximum growth rate is generally achieved at smaller and smaller
wavelengths as |X| diminishes. When |X| < m_e/m_i, new unstable
"electromagnetic-rotational" modes appear that do not depend on the equilibrium
magnetic field. Because the most rapidly-growing modes have extremely short
wavelengths when |X| is small, they are often subject to viscous or resistive
damping, which can result in suppressing all but the longest wavelengths, for
which growth is much slower. We find that this sort of damping is likely to
curtail severely the frequently-invoked mechanism for cosmological magnetic
field growth in which a magnetic field seeded by the Biermann battery is then
amplified by the magneto-rotational instability. On the other hand, the small
|X| case may introduce interesting effects in weakly-ionized disks in which
dust grains carry most of the electric charge.