title: The X-ray Evolution of Merging Galaxies

abstract:
  From a Chandra survey of nine interacting galaxy systems the evolution of
X-ray emission during the merger process has been investigated. From comparing
Lx/Lk and Lfir/Lb it is found that the X-ray luminosity peaks around 300 Myr
before nuclear coalescence, even though we know that rapid and increasing star
formation is still taking place at this time. It is likely that this drop in
X-ray luminosity is a consequence of outflows breaking out of the galactic
discs of these systems. At a time around 1 Gyr after coalescence, the
merger-remnants in our sample are X-ray dim when compared to typical X-ray
luminosities of mature elliptical galaxies. However, we do see evidence that
these systems will start to resemble typical elliptical galaxies at a greater
dynamical age, given the properties of the 3 Gyr system within our sample,
indicating that halo regeneration will take place within low Lx
merger-remnants.


title: Direct evidence for an early reionization of the Universe?

abstract:
  We examine the possible reionization of the intergalactic medium (IGM) by the
source UDF033238.7-274839.8 (hereafter HUDF-JD2), which was discovered in deep
{\it HST}/VLT/{\it Spitzer} images obtained as part of the Great Observatory
Origins Deep Survey and {\it Hubble} Ultra-Deep Field projects. Mobasher et al
(2005) have identified HUDF-JD2 as a massive ($\sim6\times10^{11}M_\odot$)
post-starburst galaxy at redshift z$\gtrsim6.5$. We find that HUDF-JD2 may be
capable of reionizing its surrounding region of the Universe, starting the
process at a redshift as high as z$\approx 15 \pm5$.


title: Deep Astrometric Standards (DAS) and Galactic Structure

abstract:
  The advent of next-generation imaging telescopes such as LSST and Pan-STARRS
has revitalized the need for deep and precise reference frames. The proposed
weak-lensing observations with these facilities put the highest demands on
image quality over wide angles on the sky. It is particularly difficult to
achieve a sub-arcsecond PSF on stacked images, where precise astrometry plays a
key role. Current astrometric standards are insufficient to achieve the science
goals of these facilities. We thus propose the establishing of a few selected
deep (V=25) astrometric standards (DAS). These will enable a reliable geometric
calibration of solid-state mosaic detectors in the focal plane of large
ground-based telescopes and make a substantial contribution to our
understanding of stellar populations in the Milky Way. In this paper we
motivate the need for such standards and discuss the strategy of their
selection and acquisition and reduction techniques. The feasibility of DAS is
demonstrated by a pilot study around the open cluster NGC 188, using the KPNO
4m CCD Mosaic camera, and by Subaru Suprime-Cam observations. The goal of
reaching an accuracy of 5-10 mas in positions and obtaining absolute proper
motions good to 2 mas/yr over a several square-degree area is challenging, but
reachable with the NOAO 4m telescopes and CCD mosaic imagers or a similar
set-up. Our proposed DAS aims to establish four fields near the Galactic plane,
at widely separated coordinates. In addition to their utilitarian purpose for
DAS, the data we will obtain in these fields will enable fundamental Galactic
science in their own right. The positions, proper motions, and VI photometry of
faint stars will address outstanding questions of Galactic disk formation and
evolution, stellar buildup and mass assembly via merger events.


title:
Identifying silicate-absorbed ULIRGs at z~1-2 in the Bootes Field using
  Spitzer/IRS

abstract:
  Using the 16$\mu$m peakup imager on the Infrared Spectrograph (IRS) on
Spitzer, we present a serendipitous survey of 0.0392 deg$^{2}$ within the area
of the NOAO Deep Wide Field Survey in Bootes. Combining our results with the
available Multiband Imaging Photometer for Spitzer (MIPS) 24$\mu$m survey of
this area, we produce a catalog of 150 16$\mu$m sources brighter than 0.18 mJy
(3$\sigma$) for which we derive measures or limits on the 16/24$\mu$m colors.
Such colors are especially useful in determining redshifts for sources whose
mid infrared spectra contain strong emission or absorption features that
characterize these colors as a function of redshift. We find that the 9.7$\mu$m
silicate absorption feature in Ultraluminous Infrared Galaxies (ULIRGs) results
in sources brighter at 16$\mu$m than at 24$\mu$m at z $\sim$ 1--1.8 by at least
20%. With a threshold flux ratio of 1.2, restricting our analysis to $>5\sigma$
detections at 16$\mu$m, and using a $3\sigma$ limit on 24$\mu$m non-detections,
the number of silicate-absorbed ULIRG candidates is 36. This defines a strong
upper limit of $\sim$920 sources deg$^{-2}$, on the population of
silicate-absorbed ULIRGs at z $\sim$ 1--1.8. This source count is about half of
the total number of sources predicted at z $\sim$ 1--2 by various
phenomenological models. We note that the high 16/24$\mu$m colors measured
cannot be reproduced by any of the mid-IR spectral energy distributions assumed
by these models, which points to the strong limitations currently affecting our
phenomenological and theoretical understanding of infrared galaxy evolution.


title:
The correlation of the Lyman-alpha forest and metals in close pairs of
  hight-redshift quasars

abstract:
  We derive the transverse flux correlation function in the Lyman-alpha forest
at z~2.1 from VLT-FORS observations of a total of 32 pairs of quasars. The
shape and correlation length of the transverse correlation function are in good
agreement with the paradigm of intergalactic medium predicted in CDM-like
models for structures formation. Using a sample of 139 Civ systems detected
along the lines of sight toward the pairs of quasars we investigate the
transverse correlation of metals on the same scales. We find that the
correlation function is consistent with that of a randomly distributed
population of Civ systems. However, we detect an important overdensity of
systems in front of a quartet.


title: Diffuse Optical Light in Galaxy Clusters I: Abell 3888

abstract:
  We are undertaking a program to measure the characteristics of the
intracluster light (total flux, profile, color, and substructure) in a sample
of 10 galaxy clusters with a range of cluster mass, morphology, and redshift.
We present here the methods and results for the first cluster in that sample,
A3888. We have identified an intracluster light (ICL) component in A3888 in V
and r that contains 13\pm5% of the total cluster light and extends to
700h_{70}^{-1}kpc (~0.3 r_{200}) from the center of the cluster. The ICL color
in our smallest radial bin is V-r = 0.3 \pm 0.1, similar to the central cluster
ellipticals. The ICL is redder than the galaxies at 400 < r < 700h_{70}^{-1}kpc
although the uncertainty in any one radial bin is high. Based on a comparison
of V-r color with simple stellar models, the ICL contains a component which
formed more than 7 Gyr ago (at z > 1), coupled with a high metallicity
(1.0Z_{\odot} < Z_{ICL} \la 2.5Z_{\odot}), and a more centralized component
which contains stars formed within the past 5 Gyr (at z ~ 1). The profile of
the ICL can be roughly fit by a shallow exponential in the outer regions and a
steeper exponential in the central region. We also find a concentration of
diffuse light around a small group of galaxies 1.4h_{70}^{-1}Mpc from the
center of the cluster. In addition, we find 3 low surface brightness features
near the cluster center which are blue (V-r = 0.0) and contain a total flux of
0.1M*. Based on these observations and X-ray and galaxy morphology, we suggest
that this cluster is entering a phase of significant merging of galaxy groups
in the core, whereupon we expect the ICL fraction to grow significantly with
the formation of a cD galaxy as well as the in-fall of groups.


title: Double barred galaxies at intermediate redshifts: A feasibility study

abstract:
  Despite the increasing number of studies of barred galaxies at intermediate
and high redshifts, double-barred (S2B) systems have only been identified in
the nearby (z<0.04) universe thus far. In this feasibility study we demonstrate
that the detection and analysis of S2Bs is possible at intermediate redshifts
(0.1 < z < 0.5) with the exquisite resolution of the Hubble Space Telescope
Advanced Camera for Surveys (HST/ACS). We identify barred galaxies in the
HST/ACS data of the Great Observatories Origins Deep Survey (GOODS) using a
novel method. The radial profile of the Gini coefficient -- a model-independent
structure parameter -- is able to detect bars in early-type galaxies that are
large enough that they might host an inner bar of sufficient angular size.
Using this method and subsequent examination with unsharp masks and ellipse
fits we identified the two most distant S2Bs currently known (at redshifts
z=0.103 and z=0.148). We investigate the underlying stellar populations of
these two galaxies through a detailed colour analysis, in order to demonstrate
the analysis that could be performed on a future sample of
intermediate-redshift S2Bs. We also identify two S2Bs and five S2B candidates
in the HST/ACS data of the Cosmic Evolution Survey (COSMOS). Our detections of
distant S2Bs show that deep surveys like GOODS and COSMOS have the potential to
push the limit for S2B detection and analysis out by a factor of ten in
redshift and lookback time (z=0.5, t=5Gyr) compared to the previously known
S2Bs. This in turn would provide new insight into the formation of these
objects.


title: Evidence for a Non-Expanding Universe: Surface Brightness Data From HUDF

abstract:
  Surface brightness data can distinguish between a Friedman-Robertson-Walker
expanding universe and a non-expanding universe. For surface brightness
measured in AB magnitudes per angular area, all FRW models, regardless of
cosmological parameters, predict that surface brightness declines with redshift
as (z+1)^-3, while any non-expanding model predicts that surface brightness is
constant with distance and thus with z. High-z UV surface brightness data for
galaxies from the Hubble Ultra Deep Field and low-z data from GALEX are used to
test the predictions of these two models up to z=6. A preliminary analysis
presented here of samples observed at the same at-galaxy wavelengths in the UV
shows that surface brightness is constant, mu=kz^0.026+-0.15, consistent with
the non-expanding model. This relationship holds if distance is linearly
proportional to z at all redshifts, but seems insensitive to the particular
choice of d-z relationship. Attempts to reconcile the data with FRW predictions
by assuming that high-z galaxies have intrinsically higher surface brightness
than low-z galaxies appear to face insurmountable problems. The intrinsic FUV
surface brightness required by the FRW models for high-z galaxies exceeds the
maximum FUV surface brightness of any low-z galaxy by as much as a factor of
40. Dust absorption appears to make such extremely high intrinsic FUV surface
brightness physically impossible. If confirmed by further analysis, the
impossibility of such high-surface-brightness galaxies would rule out all FRW
expanding universe (big bang) models.


title: The Evolved Stellar Content of NGC 147, NGC 185, and NGC 205

abstract:
  Broad-band near-infrared images are used to probe the photometric properties
of the brightest asymptotic giant branch (AGB) stars within 2 arcminutes of the
centers of the dwarf elliptical galaxies NGC 147, NGC 185, and NGC 205. Based
on the peak brightness and color of the M giant sequences, ages of 1 Gyr and
0.1 Gyr are predicted for the most recent significant star forming events in
NGC 185 and NGC 205, respectively. The brightest AGB stars in NGC 147 indicate
that the most recent significant star-forming activity in that galaxy occured
\~3 Gyr in the past. The specific frequency of C stars outside of the areas of
most recent star formation is found to agree in all three galaxies. The
fractional contribution made by C stars to the total AGB light in the K-band is
found to be highest in NGC 147 and lowest in the central regions of NGC 205,
which is qualitatively consistent with model predictions. The fractional
contribution that C stars make to the total K-band light is found to be
constant both within and between galaxies, with C stars contributing 2% of the
total K-band light. It is concluded that, when averaged over timescales of a
few Gyr, these galaxies have turned similar fractions of gas and dust,
normalised according to total galaxy mass, into stars.


title:
S Ori J053825.4-024241: A Classical T Tauri-like object at the
  substellar boundary

abstract:
  We present a spectrophotometric analysis of S Ori J053825.4-024241, a
candidate member close to the substellar boundary of the young (1-8 Myr),
nearby (~360 pc) sigma Orionis star cluster. Our optical and near-infrared
photometry and low-resolution spectroscopy indicate that S Ori J053825.4-024241
is a likely cluster member with a mass estimated from evolutionary models at
0.06+0.07-0.02 Msol, which makes the object a probable brown dwarf. The radial
velocity of S Ori J053825.4-024241 is similar to the cluster systemic velocity.
This target, which we have classified as an M 6.0+-1.0 low-gravity object,
shows excessemission in the near-infrared and anomalously strong photometric
variability for its type (from the blue to the J band), suggesting the presence
of a surrounding disc. The optical spectroscopic observations show a continuum
excess at short wavelengths and a persistent and resolved Halpha emission
(pseudo-equivalent width of ~-250 AA) in addition to the presence of other
forbidden and permitted emission lines, which we interpret as indicating
accretion from the disc and possibly mass loss. We conclude that despite the
low mass of S Ori J053825.4-024241, this object exhibits some of the properties
typical of active classical T Tauri stars.


title:
Oxygen Abundances in the Milky Way Using X-ray Absorption Measurements
  Towards Galaxy Clusters

abstract:
  We present measurements of the oxygen abundance of the Milky Way's ISM by
observing the K-shell X-ray photoionization edge towards galaxy clusters. This
effect is most easily observed towards objects with galactic columns (n_H) of a
few times 1e21 cm^-2. We measure X-ray column densities towards 11 clusters and
find that at high galactic columns above approximately 1e21 cm^-2 the X-ray
columns are generally 1.5--3.0 times greater than the 21 cm H II columns,
indicating that molecular clouds become an important contributor to n_H at
higher columns. We find the average ISM oxygen abundance to be (O/H) = (4.85
+/- 0.06) x 10^-4, or 0.99 solar when using the most recent solar photospheric
values. Since X-ray observations are sensitive to the total amount of oxygen
present (gas + dust), these results indicate a high gas to dust ratio. Also,
the oxygen abundances along lines of sight through high galactic columns (n_H)
are the same as abundances through low columns, suggesting that the composition
of denser clouds is similar to that of the more diffuse ISM.


title: A gamma-ray burst remnant in our Galaxy: HESS J1303-631

abstract:
  We present the results of our investigation of the multiwavelength data on
HESS J1303-631, an unidentified TeV source serendipitously discovered in the
Galactic plane by the HESS collaboration. These results strongly suggest the
identification of this particular source as the remnant of a Gamma-Ray Burst
(GRB) that happened some few tens of thousands years ago in our Galaxy at a
distance on the order of 10 kpc from us. We show, through detailed calculations
of particle diffusion, interaction and radiation processes of relativistic
particles in the interstellar medium, that it is possible for a GRB remnant
(GRBR) to be a strong TeV emitter with no observable synchrotron emission. We
predict spectral and spatial signatures that would unambiguously distinguish
GRBRs from ordinary supernova remnants, including: (1) large energy budgets
inferred from their TeV emission, but at the same time, (2) suppressed fluxes
in the radio through GeV wavebands; (3) extended center-filled emission with an
energy-dependent spatial profile; and (4) a possible elongation in the
direction of the past pair of GRB jets. While GRBRs can best be detected by
ground-based gamma-ray detectors, the future GLAST mission will play a crucial
role in confirming the predicted low level of GeV emission.


title:
Spectroscopic Studies of z~5.7 and z~6.5 Galaxies: Implications for
  Reionization

abstract:
  The recent development of large, complete samples which identify
high-redshift galaxies at z~5.7 and z~6.5 from deep, wide-field surveys
provides detailed information on the earliest galaxies, their numbers, spatial
and kinematic distributions, and implications for early reionization of the
IGM. In this contribution we present results of spectroscopic studies of z~5.7
and z~6.5 galaxies identified from our deep, Lyman alpha narrowband and
multicolor surveys conducted with the SuprimeCam mosaic CCD camera on the 8.3-m
Subaru telescope and observed with the DEIMOS multi-object spectrograph on
Keck. The luminosity function of the z~6.5 galaxies is shown to be similar to
the luminosity function of the z~5.7 galaxy samples, suggesting that a
substantial star-forming population is already in place at z~6.5. Comparisons
of both individual and stacked spectra of galaxies in these two samples show
that the Lyman alpha emission profiles, equivalent widths, and continuum break
strengths do not substantially change over this redshift interval. The
wide-field nature of the surveys also permits mapping the large-scale
distribution of the high-redshift galaxies in spatial structures extending
across individual SuprimeCam fields (~60 Mpc). Field-to-field variations in the
number of objects at z~6.5 may shortly be able to place constraints on the
porosity of the reionization boundary.


title: Isolated, Massive Supergiants near the Galactic Center

abstract:
  We have carried out a pilot project to assess the feasibility of using radio,
infrared, and X-ray emission to identify young, massive stars located between 1
and 25 pc from the Galactic center. We first compared catalogs compiled from
the Very Large Array, the Chandra X-ray Observatory, and 2MASS. We identified
two massive, young stars: the previously-identified star that is associated
with the radio HII region H2, and a newly-identified star that we refer to as
CXOGC J174516.1-290315. The infrared spectra of both stars exhibit very strong
Br-gamma and He I lines, and resemble those of massive supergiants that have
evolved off of the main sequence, but not yet reached the Wolf-Rayet phase. We
estimate that each star has a bolometric luminosity >10^6 L_sun. The detection
of these two sources in X-rays is surprising, because stars at similar
evolutionary states are not uniformly bright X-ray sources. Therefore, we
suggest that both stars are in binary systems that contain either OB stars
whose winds collide with those of the luminous supergiants, or compact objects
that are accreting from the winds of the supergiants. We also identify X-ray
emission from a nitrogen-type Wolf-Rayet star and place upper limits on the
X-ray luminosities of three more evolved, massive stars that previously have
been identified between 1 and 25 pc from Sgr A*. Finally, we briefly discuss
the implications that future searches for young stars will have for our
understanding of the recent history of star formation near the Galactic center.
(abridged)


title: Red giant variables: OGLE--II and MACHO

abstract:
  We review the recent impact of microlensing projects on our understanding of
pulsating red giant stars. Discussed are red giant stars' pulsation properties
(period--luminosity relations, period changes, mode switchings), Red Giant
Branch pulsations, metallicity effects and the use of red giant variables to
explore galactic structure.


title:
An explanation for long flares from extragalactic globular cluster X-ray
  sources

abstract:
  Repeatedly flaring X-ray binaries have recently been discovered in NGC 4697
by Sivakoff and collaborators. We show that these flares can be explained as
the result of eccentric binaries in globular clusters which accrete more
rapidly at periastron than during the rest of the binary orbit. We show that
theoretical timescales for producing eccentricities and circularising the
binaries are consistent with what is needed to produce the observed population
of flaring sources, although the circularisation timescales are highly
uncertain on both observational and theoretical grounds. This model makes two
clear theoretical predictions (1) the flares should be seen to be strictly
periodic if adequate sampling is provided, and that periodicity should be of
approximately 15 hours (2) this class of flaring behaviour should be seen only
in globular cluster sources, and predominantly in the densest globular
clusters. We also test the model for producing eccentricities through fly-by's
of a third star near the binary in a globular cluster against a much larger
database of millisecond pulsar observations than has been used in past work,
and find that the theoretical cross sections for producing eccentricity in
binaries are in reasonable agreement with most of the data, provided that the
pulsar ages are about $4\times10^9$ years.


title:
Using the ROSAT Catalogues to find counterparts for the second
  IBIS/ISGRI Survey Sources

abstract:
  The second IBIS/ISGRI survey has produced a catalogue containing 209 hard
X-ray sources visible down to a flux limit of around 1 milliCrab. The point
source location accuracy of typically 1-3 arcminutes has allowed the
counterparts for most of these sources to be found at other wavelengths. In
order to help identify the remaining objects, we have used the
cross-correlation recently found between the ISGRI catalogue and the ROSAT All
Sky Survey Bright Source Catalogue. In this way, for ISGRI sources which have a
counterpart in soft X-rays, we can use the much smaller ROSAT error box to
search for identifications. For this second survey, we find 114 associations
with the number expected by chance to be ~2. Of these sources, 8 are in the
list of unidentified objects and, using the smaller ROSAT error boxes, we can
find tentative counterparts for five of them. We have performed the same
analysis for the ROSAT Faint Source Catalogue, finding a further nine
associations with ISGRI unidentified sources from a total of 29 correlations,
and, notwithstanding the poorer location accuracy of these sources and higher
chance coincidence possibility, we have managed to find a counterpart for
another source. Finally, we have used the ROSAT HRI catalogue to search the
ISGRI error boxes and find 5 more X-ray objects, of which two are neither in
the bright or faint source catalogues, and for which we have managed to find
optical/near infrared associations. This makes a total of 19 objects with X-ray
counterparts for which we have found possible identifications for nine, most of
which are extragalactic.


title: Exact versus approximate solutions in Gamma-Ray Burst afterglows

abstract:
  We have recently obtained the exact analytic solutions of the relativistic
equations relating the radial and time coordinate of a relativistic thin
uniform shell expanding in the interstellar medium in the fully radiative and
fully adiabatic regimes. We here re-examine the validity of the constant-index
power-law relations between the Lorentz gamma factor and its radial coordinate,
usually adopted in the current Gamma-Ray Burst (GRB) literature on the grounds
of an "ultrarelativistic" approximation. Such expressions are found to be
mathematically correct but only approximately valid in a very limited range of
the physical and astrophysical parameters and in an asymptotic regime which is
reached only for a very short time, if any, and are shown to be not applicable
to GRBs.


title: The possibility of detecting planets in the Andromeda Galaxy

abstract:
  The Angstrom Project is using a global network of 2m-class telescopes to
conduct a high cadence pixel microlensing survey of the bulge of the Andromeda
Galaxy (M31), with the primary aim of constraining its underlying bulge mass
distribution and stellar mass function. Here we investigate the feasibility of
using such a survey to detect planets in M31. We estimate the efficiency of
detecting signals for events induced by planetary systems as a function of
planet/star mass ratio and separation, source type and background M31 surface
brightness. We find that for planets of a Jupiter-mass or above that are within
the lensing zone (~1 -3 AU) detection is possible above 3 $\sigma$, with
detection efficiencies ~3% for events associated with giant stars, which are
the typical source stars of pixel-lensing surveys. A dramatic improvement in
the efficiency of ~40 -- 60% is expected if follow-up observations on an 8m
telescope are made possible by a real-time alert system.


title:
Multifrequency VLBA Monitoring of 3C 273 during the INTEGRAL Campaign in
  2003 - I. Kinematics of the Parsec Scale Jet from 43 GHz Data

abstract:
  In this first of a series of papers describing polarimetric multifrequency
Very Long Baseline Array (VLBA) monitoring of 3C 273 during a simultaneous
campaign with the INTEGRAL gamma-ray satellite in 2003, we present 5 Stokes I
images and source models at 7 mm. We show that a part of the inner jet (1-2
milliarcseconds from the core) is resolved in a direction transverse to the
flow, and we analyse the kinematics of the jet within the first 10 mas. Based
on the VLBA data and simultaneous single-dish flux density monitoring, we
determine an accurate value for the Doppler factor of the parsec scale jet, and
using this value with observed proper motions, we calculate the Lorentz factors
and the viewing angles for the emission components in the jet. Our data
indicates a significant velocity gradient across the jet with the components
travelling near the southern edge being faster than the components with more
northern path. We discuss our observations in the light of jet precession model
and growing plasma instabilities.


title: Intra-Group Light in Hickson Compact Groups - A Wavelet Approach

abstract:
  A diffuse component of intra-group light can be observed in compact groups of
galaxies. This component is presumably due to stellar material tidally stripped
from the member galaxies of the group, which gets trapped in the group
potential. It represents an efficient tool for the determination of the stage
of dynamical evolution of such structures and for mapping the gravitational
potential of the group. Detecting this kind of low surface brightness structure
(about 1% above the sky level) is a difficult task, which is subject to many
problems like the modeling of stars and galaxy and sky subtraction. To overcome
these problems, we apply a new method, the wavelet technique OV\_WAV, with
which these low surface brightness structures can be revealed and analyzed by
separating different components according to their spatial characteristic sizes
(allowing the study of the point sources, galaxies and diffuse envelope
separately). We have analyzed 3 of the of the Hickson Compact Groups Catalogue
(HCG 79, HCG 88 and HCG 95) and were able to detect this diffuse component in
two of the studied groups: HCG 79, where the diffuse light corresponds to
$46\pm11%$ of the total B band luminosity and HCG 95, where the fraction is
$11\pm26%$. HCG 88 had no component detected, as expected by its estimated
early evolutionary stage.


title:
The peculiar type Ib supernova 2005bf: explosion of a massive He star
  with a thin hydrogen envelope?

abstract:
  We present BVRI photometry and optical spectroscopy of SN 2005bf near light
maximum. The maximum phase is broad and occurred around 2005 May 7, about forty
days after the shock breakout. SN 2005bf has a peak bolometric magnitude
M_{bol}=-18.0\pm 0.2: while this is not particularly bright, it occurred at an
epoch significantly later than other SNe Ibc, indicating that the SN possibly
ejected ~0.31 M_{sun} of 56Ni, which is more than the typical amount. The
spectra of SN 2005bf around maximum are very similar to those of the Type Ib
SNe 1999ex and 1984L about 25-35 days after explosion, displaying prominent He
I, Fe II, Ca II H & K and the near-IR triplet P Cygni lines. Except for the
strongest lines, He I absorptions are blueshifted by <~6500 km/s, and Fe II by
\~7500-8000 km/s. No other SNe Ib have been reported to have their Fe II
absorptions blueshifted more than their He I absorptions. Relatively weak
H-alpha and very weak H-beta may also exist, blueshifted by ~15,000 km/s. We
suggest that SN 2005bf was the explosion of a massive He star, possibly with a
trace of a hydrogen envelope.


title: Observational Evidence for an Age Dependence of Halo Bias

abstract:
  We study the dependence of the cross-correlation between galaxies and galaxy
groups on group properties. Confirming previous results, we find that the
correlation strength is stronger for more massive groups, in good agreement
with the expected mass dependence of halo bias. We also find, however, that for
groups of the same mass, the correlation strength depends on the star formation
rate (SFR) of the central galaxy: at fixed mass, the bias of galaxy groups
decreases as the SFR of the central galaxy increases. We discuss these findings
in light of the recent findings by Gao et al (2005) that halo bias depends on
halo formation time, in that halos that assemble earlier are more strongly
biased. We also discuss the implication for galaxy formation, and address a
possible link to galaxy conformity, the observed correlation between the
properties of satellite galaxies and those of their central galaxy.


title: Some thoughts and some new results about the Butcher-Oemler effect

abstract:
  These short notes collect some thoughts about the way Butcher-Oemler-like and
evolutionary studies are performed. We emphasize the shortcomings of several
overlooked technical ingredients in the above type of studies, with the hope of
making a useful cookbook for future works. We also briefly report new results
of an ongoing Butcher-Oemler study at intermediate redshift.


title:
A large population of galaxies 9 to 12 billion years back in the history
  of the Universe

abstract:
  To understand the evolution of galaxies, we need to know as accurately as
possible how many galaxies were present in the Universe at different epochs.
Galaxies in the young Universe have hitherto mainly been identified using their
expected optical colours, but this leaves open the possibility that a
significant population remains undetected because their colours are the result
of a complex mix of stars, gas, dust or active galactic nuclei. Here we report
the results of a flux-limited I-band survey of galaxies at look-back times of 9
to 12 billion years. We find 970 galaxies with spectroscopic redshifts between
1.4 and 5. This population is 1.6 to 6.2 times larger than previous estimates,
with the difference increasing towards brighter magnitudes. Strong ultraviolet
continua (in the rest frame of the galaxies) indicate vigorous star formation
rates of more than 10 to 100 solar masses per year. As a consequence, the
cosmic star formation rate is higher than previously measured at redshifts of 3
to 4.


title:
A Needs Analysis Study of Amateur Astronomers For the National Virtual
  Observatory

abstract:
  Through a combination of qualitative and quantitative processes, a survey was
conducted of the amateur astronomy community to identify outstanding needs
which the National Virtual Observatory (NVO) could fulfill. This is the final
report of that project, which was conducted by The American Association of
Variable Star Observers (AAVSO) on behalf of the SEGway Project at the Center
for Science Educations @ Space Sciences Laboratory, UC Berkeley.


title: Research on candidates for non-cosmological redshifts

abstract:
  (Abridged:) The paradox of apparent optical associations of galaxies with
very different redshifts, the so-called anomalous redshift problem, is around
35 years old, but is still without a clear solution and is surprisingly ignored
by most of the astronomical community. Statistical correlations among the
positions of these galaxies have been pointed out by several authors.
Gravitational lensing by dark matter has been proposed as the cause of these
correlations, although this seems to be insufficient to explain them and does
not work at all for correlations with the brightest and nearest galaxies. Some
of these cases may be just fortuitous associations in which background objects
are close in the sky to a foreground galaxy, although the statistical mean
correlations remain to be explained and some lone objects have very small
probabilities of being a projection of background objects.
  The sample of discordant redshift associations given in Arp's atlas is indeed
quite large, and most of the objects remain to be analysed thoroughly. For
about 5 years, we have been running a project to observe some of these cases in
detail, and some new anomalies have been added to those already known; For
instance, in some exotic configurations such as NGC 7603 or NEQ3, which can
even show bridges connecting four object with very different redshifts. Not
only QSOs but also emission-line galaxies in general are found to take part in
this kind of event. Other cases are analyzed: MCG 7-25-46, GC 0248+430, B2
1637+29, VV172 and Stephan's Quintet.


title:
Completing the Census of (Bright) Variable Stars in Galactic Globular
  Clusters

abstract:
  We present a long-term project aimed at completing the census of (bright)
variable stars in Galactic globular clusters. While our main aim is to obtain a
reliable assessment of the populations of RR Lyrae and type II Cepheid stars in
the Galactic globular cluster system, due attention is also being paid to other
types of variables, including SX Phoenicis stars, long-period variables, and
eclipsing binaries.


title: LISA astronomy of double white dwarf binary systems

abstract:
  The Laser Interferometer Space Antenna (LISA) will provide the largest
observational sample of (interacting) double white dwarf binaries, whose
evolution is driven by radiation reaction and other effects, such as tides and
mass transfer. We show that, depending on the actual physical parameters of a
source, LISA will be able to provide very different quality of information: for
some systems LISA can test unambiguously the physical processes driving the
binary evolution, for others it can simply detect a binary without allowing us
to untangle the source parameters and therefore shed light on the physics at
work. We also highlight that simultaneous surveys with GAIA and/or optical
telescopes that are and will become available can radically improve the quality
of the information that can be obtained.


title: Gamma-ray absorption in massive X-ray binaries

abstract:
  Gamma-ray emission in the TeV range has been detected by HESS from two X-ray
binaries: PSR B1259-63 and LS 5039. In both, the early-type star provides large
numbers of target photons for pair-production with TeV gamma-rays. This results
in a modulation of the gamma-ray flux as the relative positions of the
gamma-ray source and companion star change with orbital phase. The lightcurve
and spectrum of absorption provide useful diagnostics for the location and
nature of gamma-ray emission. The expected orbital variations of the absorption
spectrum and flux are calculated for LS 5039, PSR B1259-63 and LSI +61 303, a
system similar to LS 5039 but still undetected at TeV energies. In LS 5039,
emission close to a black hole or a neutron star primary is considered. In both
cases, the flux above 250 GeV drops by more than an order-of-magnitude near
periastron due to absorption. A black hole yields a clear spectral signature in
the average spectrum at 400 GeV. A neutron star yields more variability, with
the spectral feature moving from 200 GeV to 2 TeV. The absorbed fraction of the
flux can be as small as 20%, allowing for an almost direct view of the
intrinsic spectrum. Low variability requires emission on large scales, more
than 0.7 AU away to have <50% absorption in a jet. Such predictions are
essential to distinguish between variability due to the gamma-ray emission
process from that due to absorption. A modulation in LS 5039 would provide a
novel way to constrain the gamma-ray source. Its absence would imply that
gamma-ray emission occurs on large scales.


title: First astronomical detection of the CF+ ion

abstract:
  We report the first astronomical detection of the CF+ (fluoromethylidynium)
ion obtained by recent observations of its J = 1 - 0 (102.6 GHz), J = 2 - 1
(205.2 GHz), and J = 3 - 2 (307.7 GHz) pure rotational emissions toward the
Orion Bar. Our search for CF+, carried out using the IRAM 30m and APEX 12m
telescopes, was motivated by recent theoretical models that predict CF+
abundances of a few x E-10 in UV-irradiated molecular regions where C+ is
present. The measurements confirm the predictions. They provide support for our
current theories of interstellar fluorine chemistry, which suggest that
hydrogen fluoride should be ubiquitous in interstellar gas clouds.


title: The Advective-Acoustic instability in type II Supernovae

abstract:
  The puzzle of birth velocities of pulsars (pulsar kicks) could be solved by
an asymmetric explosion of type II Supernovae. We propose a simple
hydrodynamical mechanism in order to explain this asymmetry, through the
advective-acoustic cycle (Foglizzo 2002) : during the phase of stalled shock,
an instability based on the cycle between advected perturbations (entropy /
vorticity) and acoustic perturbations can develop between the shock and the
surface of the nascent neutron star. Eigenfrequencies are computed numerically,
improving the calculation of Houck & Chevalier (1992). The linear instability
is dominated by a mode l=1, as observed in the numerical simulations of Blondin
et al. (2003) and Scheck et al. (2004). The frequency dependence of the growth
rate reveals the presence of the advective-acoustic cycle.


title: CHANDRA Observations of the X-ray Halo around the Crab Nebula

abstract:
  Two Chandra observations have been used to search for thermal X-ray emission
from within and around the Crab Nebula. Dead-time was minimized by excluding
the brightest part of the Nebula from the field of view. A dust-scattered halo
comprising 5% of the strength of the Crab is clearly detected with surface
brightness measured out to a radial distance of 18 arcminutes. Coverage is 100%
at 4 arcminutes, 50% at 12 arcminutes, and 25% at 18 arcminutes. The observed
halo is compared with predictions based on 3 different interstellar grain
models and one can be adjusted to fit the observation. This dust halo and
mirror scattering form a high background region which has been searched for
emission from shock-heated material in an outer shell. We find no evidence for
such emission. We can set upper limits a factor of 10-1000 less than the
surface brightness observed from outer shells around similar remnants. The
upper limit for X-ray luminosity of an outer shell is about 10e34 erg/s.
Although it is possible to reconcile our observation with an 8-13 solar mass
progenitor, we argue that this is unlikely.


title: A disk of dust and molecular gas around a high-mass protostar

abstract:
  The processes leading to the birth of low-mass stars such as our Sun have
been well studied, but the formation of high-mass (> 8 x Sun's mass) stars has
heretofore remained poorly understood. Recent observational studies suggest
that high-mass stars may form in essentially the same way as low-mass stars,
namely via an accretion process, instead of via merging of several low-mass (<
8 Msun) stars. However, there is as yet no conclusive evidence. Here, we report
the discovery of a flattened disk-like structure observed at submillimeter
wavelengths, centered on a massive 15 Msun protostar in the Cepheus-A region.
The disk, with a radius of about 330 astronomical units (AU) and a mass of 1 to
8 Msun, is detected in dust continuum as well as in molecular line emission.
Its perpendicular orientation to, and spatial coincidence with the central
embedded powerful bipolar radio jet, provides the best evidence yet that
massive stars form via disk accretion in direct analogy to the formation of
low-mass stars.


title:
A "Combination Nova" Outburst in Z Andromedae: Nuclear Shell Burning
  Triggered by a Disk Instability

abstract:
  We describe observational evidence for a new kind of interacting-binary-star
outburst that involves both an accretion instability and an increase in
thermonuclear shell burning on the surface of an accreting white dwarf. We
refer to this new type of eruption as a combination nova. In late 2000, the
prototypical symbiotic star Z Andromedae brightened by roughly two magnitudes
in the optical. We observed the outburst in the radio with the VLA and MERLIN,
in the optical both photometrically and spectroscopically, in the far
ultraviolet with FUSE, and in the X-rays with both Chandra and XMM. The
two-year-long event had three distinct stages. During the first stage, the
optical rise closely resembled an earlier, small outburst that was caused by an
accretion-disk instability. In the second stage, the hot component ejected an
optically thick shell of material. In the third stage, the shell cleared to
reveal a white dwarf whose luminosity remained on the order of 10^4 Lsun for
approximately one year. The eruption was thus too energetic to have been
powered by accretion alone. We propose that the initial burst of accretion was
large enough to trigger enhanced nuclear burning on the surface of the white
dwarf and the ejection of an optically thick shell of material. This outburst
therefore combined elements of both a dwarf nova and a classical nova. Our
results have implications for the long-standing problem of producing shell
flashes with short recurrence times on low-mass white dwarfs in symbiotic
stars.


title: Infrared Surface Brightness Distances to Cepheids

abstract:
  Bayesian statistical calculations and linear-bisector calculations for
obtaining Cepheid distances and radii by the infrared surface brightness method
have been compared for a set of 38 Cepheids. The distances obtained by the two
techniques agree to 1.5%+/-0.6% and the radii agree to 1.1%+/-0.7%. Thus the
two methods yield the same distances and radii at the 2 sigma level. This
implies that the short distance to the LMC found in recent linearbisector
studies of Cepheids is not a result of simplifications in the mathematical
approach. The computed uncertainties in distance and radius are larger in the
Bayesian calculation typically by a factor of three.


title:
Outshining the quasars at reionisation: The X-ray spectrum and
  lightcurve of the redshift 6.29 Gamma-Ray Burst GRB050904

abstract:
  Gamma-ray burst (GRB) 050904 is the most distant X-ray source known, at
z=6.295, comparable to the farthest AGN and galaxies. Its X-ray flux decays,
but not as a power-law; it is dominated by large variability from a few minutes
to at least half a day. The spectra soften from a power-law with photon index
Gamma=1.2 to 1.9, and are well-fit by an absorbed power-law with possible
evidence of large intrinsic absorption. There is no evidence for discrete
features, in spite of the high signal-to-noise ratio. In the days after the
burst, GRB 050904 was by far the brightest known X-ray source at z>4. In the
first minutes after the burst, the flux was >10^{-9} erg cm^-2 s^-1 in the
0.2-10keV band, corresponding to an apparent luminosity >10^5 times larger than
the brightest AGN at these distances. More photons were acquired in a few
minutes with Swift-XRT than XMM-Newton and Chandra obtained in ~300 ks of
pointed observations of z>5 AGN. This observation is a clear demonstration of
concept for efficient X-ray studies of the high-z IGM with large area,
high-resolution X-ray detectors, and shows that early-phase GRBs are the only
backlighting bright enough for X-ray absorption studies of the IGM at high
redshift.


title:
Galaxies at z~6: The UV Luminosity Function and Luminosity Density from
  506 UDF, UDF-Ps, and GOODS i-dropouts

abstract:
  We have detected 506 i-dropouts (z~6 galaxies) in deep, wide-area HST ACS
fields: HUDF, enhanced GOODS, and HUDF-Parallel ACS fields (HUDF-Ps). The
contamination levels are <=8% (i.e., >=92% are at z~6). With these samples, we
present the most comprehensive, quantitative analyses of z~6 galaxies yet and
provide optimal measures of the UV luminosity function (LF) and luminosity
density at z~6, and their evolution to z~3. We redetermine the size and color
evolution from z~6 to z~3. Field-to-field variations (cosmic variance),
completeness, flux, and contamination corrections are modelled systematically
and quantitatively. After corrections, we derive a rest-frame continuum UV
(~1350 A) LF at z~6 that extends to M_{1350,AB} ~ -17.5 (0.04L*(z=3)). There is
strong evidence for evolution of the LF between z~6 and z~3, most likely
through a brightening (0.6+/-0.2 mag) of M* (at 99.7% confidence) though the
degree depends upon the faint-end slope. As expected from hierarchical models,
the most luminous galaxies are deficient at z~6. Density evolution (phi*) is
ruled out at >99.99% confidence. Despite large changes in the LF, the
luminosity density at z~6 is similar (0.82+/-0.21x) to that at z~3. Changes in
the mean UV color of galaxies from z~6 to z~3 suggest an evolution in dust
content, indicating the true evolution is substantially larger: at z~6 the star
formation rate density is just ~30% of the z~3 value. Our UV luminosity
function is consistent with z~6 galaxies providing the necessary UV flux to
reionize the universe.


title:
A Bar Signature and Central Disk in the Gaseous and Stellar Velocity
  Fields of NGC5448

abstract:
  We analyse SAURON kinematic maps of the inner kpc of the early-type (Sa)
barred spiral galaxy NGC5448. The observed morphology and kinematics of the
emission-line gas is patchy and perturbed, indicating clear departures from
circular motion. The kinematics of the stars is more regular, and display a
small inner disk-like system embedded in a large-scale rotating structure. We
focus on the [OIII] gas, and use a harmonic decomposition formalism to analyse
the gas velocity field. The higher-order harmonic terms and the main kinematic
features of the observed data are consistent with an analytically constructed
simple bar model. The bar model is derived using linear theory, considering an
m=2 perturbation mode, and with bar parameters which are consistent with the
large-scale bar detected via imaging. We also study optical and near infra-red
images to reveal the asymmetric extinction in NGC5448, and we recognise that
some of the deviations between the data and the analytical bar model may be due
to these complex dust features. Our study illustrates how the harmonic
decomposition formalism can be used as a powerful tool to quantify non-circular
motions in observed gas velocity fields.


title: Chemistry and line emission of outer protoplanetary disks

abstract:
  The structure and chemistry of protoplanetary disks depends strongly on the
nature of the central star around which it has formed. The dust temperature is
mainly set by the stellar luminosity, while the chemistry of the upper disk
layers depends on the amount of intercepted UV and X-ray flux. We will study
the differences in chemistry, thermal sturcture and line emission around Herbig
Ae/Be, T Tauri stars and low mass M dwarfs. Predictions will be made for future
observations with SOFIA and Herschel.


title:
Is there Evidence for Flat Cores in the Halos of Dwarf Galaxies?: The
  Case of NGC 3109 and NGC 6822

abstract:
  Two well studied dwarf galaxies -- NGC 3109 and NGC 6822 -- present some of
the strongest observational support for a flat core at the center of galactic
dark matter (DM) halos. We use detailed cosmologically motivated numerical
models to investigate the systematics and the accuracy of recovering parameters
of the galaxies. Some of our models match the observed structure of the two
galaxies remarkably well. Our analysis shows that the rotation curves of these
two galaxies are instead quite compatible with their DM halos having steep
cuspy density profiles. The rotation curves in our models are measured using
standard observational techniques. The models reproduce the rotation curves of
both galaxies, the disk surface brightness profiles as well as the profile of
isophotal ellipticity and position angle. The models are centrally dominated by
baryons; however, the dark matter component is globally dominant. The simulated
disk mass is marginally consistent with a stellar mass-to-light ratio in
agreement with the observed colors. We show that non-circular motions combined
with gas pressure support and projection effects results in a large
underestimation of the circular velocity in the central $\sim 1$ kpc region,
creating the illusion of a constant density core. Although the systematic
effects mentioned above are stronger in barred systems, they are also present
in axisymetric disks. Our results strongly suggest that there is no
contradiction between the observed rotation curves in dwarf galaxies and the
cuspy central dark matter density profiles predicted by Cold Dark Matter
models.


title: GMRT observations of the field of INTEGRAL X-ray sources- I

abstract:
  The INTEGRAL observatory has discovered a variety of hard X-ray sources in
the Galactic plane since its launch. Using GMRT, we have made repeated
observations of these sources to search for the radio counterparts of seventeen
of them at low frequencies. The source positions were taken from the various
ATEL and IAUC reporting their discovery. Possible radio counterparts for seven
of these sources namely, IGR J06074+2205, IGR J15479-4529, IGR J16479-4514, IGR
J17091-3624, IGR J18027-1455, IGR J18539+0727 and IGR J21247+5058 were detected
within 3$\sigma$ of the position uncertainty derived from the INTEGRAL
observations. The offset in the radio position was calculated using the
positions mentioned in the ATEL. We have also analyzed the available NVSS
images for a few of these fields at 1.4 GHz along with our observations. In
this paper we present the radio images and the best fit positions for the
positive detections. The X-ray variability for few of the sources within the
time scales of 100 s to 1 ks as seen in the RXTE/PCA light curves suggests
their Galactic origin and possible binary nature. We discuss briefly the
characteristics of these sources from the available information at different
wave bands.


title: Black Hole Mass of the Ultraluminous X-ray source M82 X-1

abstract:
  We report the first clear evidence for the simultaneous presence of a low
frequency break and a QPO in the fluctuation power spectrum of a well known
ultraluminous X-ray source (ULX) in M82 using long XMM-Newton observations. The
break occurs at a frequency of 34.2_{-3}^{+6}mHz. The QPO has a centroid at
114.3\pm1.5mHz, a coherence Q~3.5 and an amplitude (rms) of 19% in the 2-10keV
band. The power spectrum is approximately flat below the break frequency and
then falls off above the break frequency as a power law with the QPO
superimposed. This form of the power spectrum is characteristic of the Galactic
X-ray binaries (XRBs) in their high or intermediate states. M82 X-1 was likely
in an intermediate state during the observation. The EPIC PN spectrum is well
described by a model comprising an absorbed power-law (Gamma~2) and an iron
line at ~6.6keV with a width sigma~0.2keV and an equivalent width of ~180eV.
Using the well established correlations between the power and energy spectral
parameters for XRBs, we estimate a black hole mass for M82 X-1 in the range of
25-520Msun including systematic errors that arise due to the uncertainty in the
calibration of the photon spectral index versus QPO frequency relation.


title: Cluster Merger Variance and the Luminosity Gap Statistic

abstract:
  The presence of multiple luminous galaxies in clusters can be explained by
the finite time over which a galaxy sinks to the center of the cluster and
merges with the the central galaxy. The simplest measurable statistic to
quantify the dynamical age of a system of galaxies is the luminosity
(magnitude) gap, which is the difference in photometric magnitude between the
two most luminous galaxies. We present a simple analytical estimate of the
luminosity gap distribution in groups and clusters as a function of dark matter
halo mass. The luminosity gap is used to define "fossil" groups; we expect the
fraction of fossil systems to exhibit a strong and model-independent trend with
mass: ~1-3% of massive clusters and ~5-40% of groups should be fossil systems.
We also show that, on cluster scales, the observed intrinsic scatter in the
central galaxy luminosity-halo mass relation can be ascribed to dispersion in
the merger histories of satellites within the cluster. We compare our
predictions to the luminosity gap distribution in a sample of 730 clusters in
the Sloan Digital Sky Survey C4 Catalog and find good agreement. This suggests
that theoretical excursion set merger probabilities and the standard theory of
dynamical segregation are valid on cluster scales.


title:
Measurements of the f-Values of the Resonance Transitions of Ni II at
  1317.217A and 1370.132A

abstract:
  We have retrieved high-resolution UV spectra of 69 hot stars from the HST
archive and determined the strengths of the interstellar Ni II absorption
features at 1317.217A. We then compared them to absorptions from either the
transitions at 1741.553A (covered in the spectra of 21 of the stars) or the one
at 1370.132A (seen for the remaining 48 stars). All spectra were recorded by
the either the E140M, E140H, or E230H gratings of STIS. By comparing the
strengths of the two lines in each spectrum and evaluating a weighted average
of all such comparisons, we have found that the f-value of the 1317A line is
1.34 +/-0.019 times the one at 1741A and 0.971 +/-0.014 times that of the one
at 1370A. We adopt as a comparison standard an experimentally determined
f-value for the 1741A line (known to 10% accuracy), so that f(1317A) = 0.0571
+/-0.006. It follows from this f-value and our measured line-strength ratios
that f(1370A) = 0.0588 +/-0.006. As an exercise to validate our methodology, we
compared the 1317A transition to another Ni II line at 1454.842A and arrived at
an f-value for the latter that is consistent with a previously measured
experimental value to within the expected error.


title:
Spitzer 70 and 160-micron Observations of the Extragalactic First Look
  Survey

abstract:
  We present Spitzer 70um and 160um observations of the Spitzer extragalactic
First Look Survey (xFLS). The data reduction techniques and the methods for
producing co-added mosaics and source catalogs are discussed. Currently, 26% of
the 70um sample and 49% of the 160um-selected sources have redshifts. The
majority of sources with redshifts are star-forming galaxies at z<0.5, while
about 5% have infrared colors consistent with AGN. The observed infrared colors
agree with the spectral energy distribution (SEDs) of local galaxies previously
determined from IRAS and ISO data. The average 160um/70um color temperature for
the dust is Td~= 30+/-5 K, and the average 70um/24um spectral index is alpha~=
2.4+/-0.4. The observed infrared to radio correlation varies with redshift as
expected out to z~1 based on the SEDs of local galaxies. The xFLS number counts
at 70um and 160um are consistent within uncertainties with the models of galaxy
evolution, but there are indications that the current models may require slight
modifications. Deeper 70um observations are needed to constrain the models, and
redshifts for the faint sources are required to measure the evolution of the
infrared luminosity function.


title: Imprints of Environment on Cluster and Field Late-type Galaxies at z~1

abstract:
  We present a comparison of late-type galaxies (Sa and later) in intermediate
redshift clusters and the field using ACS imaging of four cluster fields:
CL0152-1357, CL1056-0337 (MS1054), CL1604+4304, and CL1604+4321. Concentration,
asymmetry, and clumpiness parameters are calculated for each galaxy in blue
(F606W or F625W) and red (F775W or F814W) filters. Galaxy half-light radii,
disk scale lengths, color gradients, and overall color are compared. We find
marginally significant differences in the asymmetry distributions of spiral and
irregular galaxies in the X-ray luminous and X-ray faint clusters. The massive
clusters contain fewer galaxies with large asymmetries. The physical sizes of
the cluster and field populations are similar; no significant differences are
found in half-light radii or disk scale lengths. The most significant
difference is in rest-frame $U-B$ color. Late-type cluster galaxies are
significantly redder, $\sim 0.3$ magnitudes at rest-frame $U-B$, than their
field counterparts. Moreover, the intermediate-redshift cluster galaxies tend
to have blue inward color gradients, in contrast to the field galaxies, but
similar to late-type galaxies in low redshift clusters. These blue inward color
gradients are likely to be the result of enhanced nuclear star formation rates
relative to the outer disk. Based on the significant rest-frame color
difference, we conclude that late-type cluster members at $z\sim0.9$ are not a
pristine infalling field population; some difference in past and/or current
star formation history is already present. This points to high redshift
``groups'', or filaments with densities similar to present-day groups, as the
sites where the first major effects of environment are imprinted.


title:
The 21-cm Background from the Cosmic Dark Ages: Minihalos and the
  Intergalactic Medium before Reionization

abstract:
  The H atoms inside minihalos (i.e. halos with virial temperatures T_vir <
10^4 K, in the mass range roughly from 10^4 M_sun to 10^8 M_sun) during the
cosmic dark ages in a LCDM universe produce a redshifted background of
collisionally-pumped 21-cm line radiation which can be seen in emission
relative to the cosmic microwave background (CMB). Previously, we used
semi-analytical calculations of the 21-cm signal from individual halos of
different mass and redshift and the evolving mass function of minihalos to
predict the mean brightness temperature of this 21-cm background and its
angular fluctuations. Here we use high-resolution cosmological N-body and
hydrodynamic simulations of structure formation at high redshift (z > 8) to
compute the mean brightness temperature of this background from both minihalos
and the intergalactic medium (IGM) prior to the onset of Ly-alpha radiative
pumping. We find that the 21-cm signal from gas in collapsed, virialized
minihalos dominates over that from the diffuse shocked gas in the IGM.


title: An Improved Virial Estimate of Solar Active Region Energy

abstract:
  The MHD virial theorem may be used to estimate the magnetic energy of active
regions based on vector magnetic fields measured at the photosphere or
chromosphere. However, the virial estimate depends on the measured vector
magnetic field being force-free. Departure from force-freeness leads to an
unknown systematic error in the virial energy estimate, and an origin
dependence of the result. We present a method for estimating the systematic
error by assuming that magnetic forces are confined to a thin layer near the
photosphere. If vector magnetic field measurements are available at two levels
in the low atmosphere (e.g. the photosphere and the chromosphere), the
systematic error may be directly calculated using the observed horizontal and
vertical field gradients, resulting in an energy estimate which is independent
of the choice of origin. If (as is generally the case) measurements are
available at only one level, the systematic error may be approximated using the
observed horizontal field gradients together with a simple linear force-free
model for the vertical field gradients. The resulting `improved' virial energy
estimate is independent of the choice of origin, but depends on the choice of
the model for the vertical field gradients, i.e. the value of the linear
force-free parameter $\alpha$. This procedure is demonstrated for five vector
magnetograms, including a chromospheric magnetogram.


title: New Keck Observations of Lithium in Very Metal-poor Stars

abstract:
  Lithium abundances have been determined in more than 100 metal-poor halo
stars both in the field and in clusters. From these data we find trends of Li
with both temperature and metallicity and a real dispersion in Li abundances in
the Spite Li plateau. We attribute this dispersion primarily to Li depletion
(presumably due to extra mixing induced by stellar rotation) and to Galactic
chemical evolution. We derive a primordial Li of 2.44 $\pm$0.18 for A(Li)$_p$ =
log N(Li/H) + 12.00. This agrees with the Li abundances predicted by the $WMAP$
results. For stars cooler than the Li plateau we have evidence that Li
depletion sets in at hotter temperatures for the higher metallicity stars than
for the low-metal stars. This is the opposite sense of predictions from stellar
models. The smooth transition of the Li content from the Li plateau stars to
the cool stars adds weight to the inference of Li depletion in the plateau
stars.


title:
The ACS Virgo Cluster Survey IX: The Color Distributions of Globular
  Cluster Systems in Early-Type Galaxies

abstract:
  We present the color distributions of globular cluster (GC) systems for 100
Virgo cluster early-type galaxies observed in the ACS Virgo Cluster Survey. The
color distributions of individual GC systems are consistent with continuous
trends across galaxy luminosity, color, and stellar mass. On average, almost
all galaxies possess a component of metal-poor GCs, with the average fraction
of metal-rich GCs ranging from 15 to 60%. The colors of both subpopulations
correlate with host galaxy luminosity and color, with the red GCs having a
steeper slope. To convert color to metallicity, we also introduce a preliminary
(g-z)-[Fe/H] relation calibrated to Galactic, M49 and M87 GCs. This relation is
nonlinear with a steeper slope for [Fe/H] < -0.8. As a result, the
metallicities of the metal-poor and metal-rich GCs vary similarly with respect
to galaxy luminosity and stellar mass, with relations of [Fe/H]_MP ~ L^0.16 ~
M_star^0.17 and [Fe/H]_MR ~ L^0.26 ~ M_star^0.22, respectively. Although these
relations are shallower than the mass-metallicity relation predicted by wind
models and observed for dwarf galaxies, they are very similar to the
mass-metallicity relation for star forming galaxies in the same mass range. The
offset between the two GC populations varies slowly (~ M_star^0.05) and is
approximately 1 dex across three orders of magnitude in mass, suggesting a
nearly universal amount of enrichment between the formation of the two
populations of GCs. We also find that although the metal-rich GCs show a larger
dispersion in color, it is the *metal-poor GCs* that have an equal or larger
dispersion in metallicity. Like the color-magnitude relation, these relations
derived from globular clusters present stringent constraints on the formation
and evolution of early-type galaxies. (Abridged)


title: The Rate of Type Ia Supernovae at High Redshift

abstract:
  We derive the rates of Type Ia supernovae (SNIa) over a wide range of
redshifts using a complete sample from the IfA Deep Survey. This sample of more
than 100 SNIa is the largest set ever collected from a single survey, and
therefore uniquely powerful for a detailed supernova rate (SNR) calculation.
Measurements of the SNR as a function of cosmological time offer a glimpse into
the relationship between the star formation rate (SFR) and Type Ia SNR, and may
provide evidence for the progenitor pathway. We observe a progressively
increasing Type Ia SNR between redshifts z~0.3-0.8. The Type Ia SNR
measurements are consistent with a short time delay (t~1 Gyr) with respect to
the SFR, indicating a fairly prompt evolution of SNIa progenitor systems. We
derive a best-fit value of SFR/SNR 580 h_70^(-2) M_solar/SNIa for the
conversion factor between star formation and SNIa rates, as determined for a
delay time of t~1 Gyr between the SFR and the Type Ia SNR. More complete
measurements of the Type Ia SNR at z>1 are necessary to conclusively determine
the SFR--SNR relationship and constrain SNIa evolutionary pathways.


title: An analysis of the transit times of TrES-1b

abstract:
  The presence of a second planet in a known, transiting-planet system will
cause the time between transits to vary. These variations can be used to
constrain the orbital elements and mass of the perturbing planet. We analyse
the set of transit times of the TrES-1 system given in Charbonneau et al.
(2005). We find no convincing evidence for a second planet in the TrES-1 system
from that data. By further analysis, we constrain the mass that a perturbing
planet could have as a function of the semi-major axis ratio of the two planets
and the eccentricity of the perturbing planet. Near low-order, mean-motion
resonances (within ~1% fractional deviation), we find that a secondary planet
must generally have a mass comparable to or less than the mass of the
Earth--showing that this data is the first to have sensitivity to sub
Earth-mass planets. We compare the sensitivity of this technique to the mass of
the perturbing planet with future, high-precision radial velocity measurements.


title: Extinctions at 7um and 15um from the ISOGAL survey

abstract:
  The extinction laws at 7um and 15um are derived for more than 120 sightlines
in the inner Galactic plane based on the ISOGAL survey data and the
near-infrared data from DENIS and 2MASS. The tracers are the ISOGAL point
sources with [7]-[15]<0.4 which are RGB tip stars or early AGB stars with
moderate mass loss. They have well-defined intrinsic color indices (J-Ks)_0,
(Ks-[7])_0 and (Ks-[15])_0. By a linear fitting of the observed color indices
Ks-[7] and Ks-[15] to the observed J-Ks, we obtain the ratio between the
E(Ks-[7]) and E(Ks-[15]) color excesses and E(J-Ks). We infer the selective
extinctions at 7 and 15um in terms of the near-infrared extinction in the Ks
band. The distribution of the derived extinctions around 7 micron (A_7) is well
represented by a Gaussian function, with the peak at about 0.47A_Ks and ranging
from 0.33 to 0.55A_Ks (using the near-infrared extinctions of Rieke & Lebovsky
1985). There is some evidence that A_7/A_Ks may vary significantly depending on
the line of sight. The derived selective extinction at 15um suffers uncertainty
mainly from the dispersion in the intrinsic color index (Ks-[15])_0 which is
affected by dust emission from mass-losing AGB stars. The peak value of A_15 is
around 0.40A_Ks.


title:
The new record holder for the most iron-poor star: HE 1327-2326, a dwarf
  or subgiant with [Fe/H]=-5.4

abstract:
  We describe the discovery of HE 1327-2326, a dwarf or subgiant with
[Fe/H]}=-5.4. The star was found in a sample of bright metal-poor stars
selected from the Hamburg/ESO survey. Its abundance pattern is characterized by
very high C and N abundances. The detection of Sr which is overabundant by a
factor of 10 as compared to iron and the Sun, suggests that neutron-capture
elements had already been produced in the very early Galaxy. A puzzling Li
depletion is observed in this unevolved star which contradicts the value of the
primordial Li derived from WMAP and other Li studies. Possible scenarios for
the origin of the abundance pattern (Pop. II or Pop. III) are presented as well
as an outlook on future observations.


title:
Dynamical Stability and Habitability of Gamma Cephei Binary-Planetary
  System

abstract:
  It has been suggested that the long-lived residual radial velocity variations
observed in the precision radial velocity measurements of the primary of Gamma
Cephei (HR8974, HD222404, HIP116727) are likely due to a Jupiter-like planet
around this star (Hatzes et al, 2003). In this paper, the orbital dynamics of
this plant is studied and also the possibility of the existence of a
hypothetical Earth-like planet in the habitable zone of its central star is
discussed. Simulations, which have been carried out for different values of the
eccentricity and semimajor axis of the binary, as well as the orbital
inclination of its Jupiter-like planet, expand on previous studies of this
system and indicate that, for the values of the binary eccentricity smaller
than 0.5, and for all values of the orbital inclination of the Jupiter-like
planet ranging from 0 to 40 degrees, the orbit of this planet is stable. For
larger values of the binary eccentricity, the system becomes gradually
unstable. Integrations also indicate that, within this range of orbital
parameters, a hypothetical Earth-like planet can have a long-term stable orbit
only at distances of 0.3 to 0.8 AU from the primary star. The habitable zone of
the primary, at a range of approximately 3.1 to 3.8 AU, is, however, unstable.


title:
Discovery and identification of the very high redshift afterglow of GRB
  050904

abstract:
  In 2000, Lamb and Reichart predicted that gamma-ray bursts (GRBs) and their
afterglows occur in sufficient numbers and at sufficient brightnesses at very
high redshifts (z > 5) to eventually replace quasars as the preferred probe of
element formation and reionization in the early universe and to be used to
characterize the star-formation history of the early universe, perhaps back to
when the first stars formed. Here we report the discovery of the afterglow of
GRB 050904 and the identification of GRB 050904 as the first very high redshift
GRB. We measure its redshift to be 6.39(+0.11,-0.12), which is consistent with
the reported spectroscopic redshift (6.29 +/- 0.01). Furthermore, just redward
of Ly-alpha the flux is suppressed by a factor of three on the first night, but
returns to expected levels by the fourth night. We propose that this is due to
absorption by molecular hydrogen that was excited to rovibrational states by
the GRB's prompt emission, but was then overtaken by the jet. Now that very
high redshift GRBs have been shown to exist, and at least in this case the
afterglow was very bright, observing programs that are designed to capitalize
on this science will likely drive a new era of study of the early universe,
using GRBs as probes.


title: Superburst: surface phenomenon of compact objects

abstract:
  We suggest that superbursts from some low mass X-ray binaries may be due to
breaking and re-formation of diquark pairs, on the surface of realistic strange
stars. Diquarks are expected to break up due to the explosion and shock of the
thermonuclear process. The subsequent production of copious diquark pairing may
produce sufficient energy to produce the superbursts.


title: Near-infrared line spectropolarimetry of hot massive stars

abstract:
  In order to study the inner parts of the circumstellar material around
optically faint, infrared bright objects, we present the first
medium-resolution spectropolarimetric data taken in the near-infrared. In this
paper we discuss Pa beta line data of GL 490, a well-known embedded massive
young stellar object, and of MWC 349A and MWC 342, two optically faint stars
that are proposed to be in the pre-main sequence phase of evolution. As a check
on the method, the classical Be star zeta Tau, known to display line
polarization changes at optical wavelengths, was observed as well. Three of our
targets show a ``line effect'' across Pa beta. For zeta Tau and MWC 349A this
line effect is due to depolarisation by a circumstellar electron-scattering
disk. In both cases, the position angle of the polarisation is consistent with
that of the larger scale disks imaged at other wavelengths, validating infrared
spectropolarimetry as a means to detect flattening on small scales. The
tentative detection of a rotation in the polarization position angle at Pa beta
in the embedded massive young stellar object GL 490 suggests the presence of a
small scale rotating accretion disk with an inner hole - similar to those
recently discovered at optical wavelengths in Herbig Ae and T Tauri stars.


title:
First results from a VLBA proper motion survey of H2O masers in low-mass
  YSOs: the Serpens core and RNO15-FIR

abstract:
  This article reports first results of a long-term observational program aimed
to study the earliest evolution of jet/disk systems in low-mass YSOs by means
of VLBI observations of the 22.2 GHz water masers. We report here data for the
cluster of low-mass YSOs in the Serpens molecular core and for the single
object RNO~15-FIR. Towards Serpens SMM1, the most luminous sub-mm source of the
Serpens cluster, the water maser emission comes from two small (< 5 AU in size)
clusters of features separated by ~25 AU, having line of sight velocities
strongly red-shifted (by more than 10 km/s) with respect to the LSR velocity of
the molecular cloud. The two maser clusters are oriented on the sky along a
direction that is approximately perpendicular to the axis of the radio
continuum jet observed with the VLA towards SMM1. The spatial and velocity
distribution of the maser features lead us to favor the interpretation that the
maser emission is excited by interaction of the receding lobe of the jet with
dense gas in the accretion disk surrounding the YSO in SMM1. Towards
RNO~15-FIR, the few detected maser features have both positions and (absolute)
velocities aligned along a direction that is parallel to the axis of the
molecular outflow observed on much larger angular scales. In this case the
maser emission likely emerges from dense, shocked molecular clumps displaced
along the axis of the jet emerging from the YSO. The protostar in Serpens SMM1
is more massive than the one in RNO~15-FIR. We discuss the case where a high
mass ejection rate can generate jets sufficiently powerful to sweep away from
their course the densest portions of circumstellar gas. In this case, the
excitation conditions for water masers might preferably occur at the interface
between the jet and the accretion disk, rather than along the jet axis.


title: RHESSI and SOHO/CDS Observations of Explosive Chromospheric Evaporation

abstract:
  Simultaneous observations of explosive chromospheric evaporation are
presented using data from the Reuven Ramaty High Energy Solar Spectroscopic
Imager (RHESSI) and the Coronal Diagnostic Spectrometer (CDS) onboard SOHO. For
the first time, co-spatial imaging and spectroscopy have been used to observe
explosive evaporation within a hard X-ray emitting region. RHESSI X-ray images
and spectra were used to determine the flux of non-thermal electrons
accelerated during the impulsive phase of an M2.2 flare. Assuming a
thick-target model, the injected electron spectrum was found to have a spectral
index of ~7.3, a low energy cut-off of ~20 keV, and a resulting flux of
>4x10^10 ergs cm^-2 s^-1. The dynamic response of the atmosphere was determined
using CDS spectra, finding a mean upflow velocity of 230+/-38 km s^-1 in Fe XIX
(592.23A), and associated downflows of 36+/-16 km s^-1 and 43+/-22 km s^-1 at
chromospheric and transition region temperatures, respectively, relative to an
averaged quiet-Sun spectra. The errors represent a 1 sigma dispersion. The
properties of the accelerated electron spectrum and the corresponding
evaporative velocities were found to be consistent with the predictions of
theory.


title: MONDian Cosmological Simulations

abstract:
  We present results derived from a high-resolution cosmological N-body
simulation in which the equations of motion have been changed to account for
MOdified Newtonian Dynamics (MOND). It is shown that a low-Omega0 MONDian model
with an appropriate choice for the normalisation sigma8 of the primordial
density fluctuations can lead to similar clustering properties at redshift z=0
as the commonly accepted (standard) LCDM model. However, such a model shows no
significant structures at high redshift with only very few objects present
beyond z>3. For the current implementation of MOND density profiles of
gravitationally bound objects at z=0 can though still be fitted by the
universal NFW profile.


title: Close frequencies in pulsating stars: common and mysterious!

abstract:
  Amplitude and phase variability are commonly found in many different types of
pulsating stars. This suggests a common, presently unknown physical origin. We
have examined the phenomenon in several Delta Scuti stars with extensive data
and find the beating of close frequencies to be responsible. This is
demonstrated for the star FG Vir by testing the relationship between the
observed amplitude and phase variations. Most close frequency pairs are
situated near the observed or theoretically predicted frequencies of radial
modes. The large number of detected close frequencies excludes the possibility
of accidental frequency agreements.


title:
Properties of Early-Type, Dry Galaxy Mergers and the Origin of Massive
  Elliptical Galaxies

abstract:
  The luminosity dependence of kinematical and isophotal properties of
elliptical galaxies is investigated using numerical simulations of galaxy
merging, combined with semi-analytical models of hierarchical structure
formation. Mergers of spiral galaxies as the only formation mechanism for
elliptical galaxies can neither reproduce the kinematical and photometric
properties of very massive elliptical galaxies nor the change from rotationally
flattened disky to anisotropic boxy systems with increasing luminosity. We
present numerical simulations showing that binary mergers of early-type
galaxies open an additional channel for the formation of anisotropic, slowly
rotating and boxy ellipticals. Including this channel in a semi-analytical
model we can successfully reproduce the observed trend that more luminous giant
ellipticals are more boxy and less flattened by rotation. This trend can be
strengthened by suppressing residual gas infall and star formation for galaxies
with stellar bulge masses $M_* \geq 3 \times 10^{10} M_{\odot}$. Hence we
propose that mergers of early-type galaxies play an important role for the
assembly of massive elliptical galaxies.


title: Forced oscillations in a hydrodynamical accretion disk and QPOs

abstract:
  This is the second of a series of papers aimed to look for an explanation on
the generation of high frequency quasi-periodic oscillations (QPOs) in
accretion disks around neutron star, black hole, and white dwarf binaries. The
model is inspired by the general idea of a resonance mechanism in the accretion
disk oscillations as was already pointed out by Abramowicz & Klu{\'z}niak
(\cite{Abramowicz2001}). In a first paper (P\'etri \cite{Petri2005a}, paper I),
we showed that a rotating misaligned magnetic field of a neutron star gives
rise to some resonances close to the inner edge of the accretion disk. In this
second paper, we suggest that this process does also exist for an asymmetry in
the gravitational potential of the compact object. We prove that the same
physics applies, at least in the linear stage of the response to the
disturbance in the system. This kind of asymmetry is well suited for neutron
stars or white dwarfs possessing an inhomogeneous interior allowing for a
deviation from a perfectly spherically symmetric gravitational field. We show
by a linear analysis that the disk initially in a cylindrically symmetric
stationary state is subject to three kinds of resonances: a corotation
resonance, a Lindblad resonance due to a driven force and a parametric sonance.
The highest kHz QPOs are then interpreted as the orbital frequency of the disk
at locations where the response to the resonances are maximal. It is also found
that strong gravity is not required to excite the resonances.


title: Quantitative Spectroscopy of BA-type Supergiants

abstract:
  Luminous BA-SGs allow topics ranging from NLTE physics and the evolution of
massive stars to the chemical evolution of galaxies and cosmology to be
addressed. A hybrid NLTE technique for the quantitative spectroscopy of BA-SGs
is discussed. Thorough tests and first applications of the spectrum synthesis
method are presented for four bright Galactic objects. Stellar parameters are
derived from spectroscopic indicators. The internal accuracy of the method
allows the 1sigma-uncertainties to be reduced to <1-2% in Teff and to
0.05-0.10dex in log g. Elemental abundances are determined for over 20 chemical
species, with many of the astrophysically most interesting in NLTE. The NLTE
computations reduce random errors and remove systematic trends in the analysis.
Inappropriate LTE analyses tend to systematically underestimate iron group
abundances and overestimate the light and alpha-process element abundances by
up to factors of 2-3 on the mean. Contrary to common assumptions, significant
NLTE abundance corrections of ~0.3dex can be found even for the weakest lines.
NLTE abundance uncertainties amount to typically 0.05-0.10dex (random) and
\~0.10dex (systematic 1sigma-errors). Near-solar abundances are derived for the
heavier elements, and patterns indicative of mixing with nuclear-processed
matter for the light elements. These imply a blue-loop scenario for Eta Leo,
while the other three objects appear to have evolved directly from the main
sequence. In the most ambitious computations several ten-thousand spectral
lines are accounted for, permitting the accurate reproduction of the entire
observed spectra from the visual to NIR. This prerequisite for the quantitative
interpretation of medium-resolution spectra opens up BA-SGs as versatile tools
for extragalactic stellar astronomy beyond the Local Group. (abridged)


title: A simple model of radiative emission in M87

abstract:
  We present a simple physical model of the central source emission in the M87
galaxy. It is well known that the observed X-ray luminosity from this galactic
nucleus is much lower than the predicted one, if a standard radiative
efficiency is assumed. Up to now the main model invoked to explain such a
luminosity is the ADAF (Advection-Dominated-Accretion-Flow) model. Our approach
supposes only a simple axis-symmetric adiabatic accretion with a low angular
momentum together with the bremsstrahlung emission process in the accreting
gas. With no other special hypothesis on the dynamics of the system, this model
agrees well enough with the luminosity value measured by Chandra.


title: A broadband FFT spectrometer for radio and millimeter astronomy

abstract:
  The core architecture, tests in the lab and first results of a Fast Fourier
Transform (FFT) spectrometer are described. It is based on a commercially
available fast digital sampler (AC240) with an on-board Field Programmable Gate
Array (FPGA). The spectrometer works continuously and has a remarkable total
bandwidth of 1 GHz, resolved into 16384 channels. The data is sampled with 8
bits, yielding a dynamic range of 48 dB. An Allan time of more than 2000 s and
an SFDR of 37 dB were measured. First light observations with the KOSMA
telescope show a perfect spectrum without internal or external spurious
signals.


title: Hot subdwarfs in the Galactic Bulge

abstract:
  Recent observations and theories suggest that extreme horizontal branch (EHB)
stars and their progeny should be the cause of the UV excess seen in the
spectra of many elliptical galaxies. Since the Galactic Bulge is the closest
representation of an old, metal-rich spheroid in which we are able to study the
EHB scenario in detail, we obtained spectra of bulge EHB star candidates and we
confirm their status as hot evolved stars. It is the first time that such stars
are unambiguously identified in the Galactic Bulge.


title:
A general solution to non-linear particle acceleration at
  non-relativistic shock waves

abstract:
  Diffusive acceleration at collisionless shock waves remains one of the most
promising acceleration mechanisms for the description of the origin of cosmic
rays at all energies. A crucial ingredient to be taken into account is the
reaction of accelerated particles on the shock, which in turn determines the
efficiency of the process. Here we propose a semi-analytical kinetic method
that allows us to calculate the shock modification induced by accelerated
particles together with the efficiency for particle acceleration and the
spectra of accelerated particles. The shock modification is calculated for
arbitrary environment parameters (Mach number, maximum momentum, density) and
for arbitrary diffusion properties of the medium. Several dependences of the
diffusion coefficient on particle momentum and location are considered to
assess the goodness of the method.


title:
First ground-based 200-um observing with THUMPER on JCMT - sky
  characterisation and planet maps

abstract:
  We present observations that were carried out with the Two HUndred Micron
PhotometER (THUMPER) mounted on the James Clerk Maxwell Telescope (JCMT) in
Hawaii, at a wavelength of 200 um (frequency 1.5 THz). The observations utilise
a small atmospheric window that opens up at this wavelength under very dry
conditions at high-altitude observing sites. The atmosphere was calibrated
using the sky-dipping method and a relation was established between the optical
depth, tau, at 1.5 THz and that at 225 GHz: tau_1.5THz = (95 +/-
10)*tau_225GHz. Mars and Jupiter were mapped from the ground at this wavelength
for the first time, and the system characteristics measured. A noise equivalent
flux density (NEFD) of ~65 +/- 10 Jy (1 sigma 1 second) was measured for the
THUMPER-JCMT combination, consistent with predictions based upon our laboratory
measurements. The main-beam resolution of 14 arcsec was confirmed and an
extended error-beam detected at roughly two-thirds of the magnitude of the main
beam. Measurements of the Sun allow us to estimate that the fraction of the
power in the main beam is ~15%, consistent with predictions based on modelling
the dish surface accuracy. It is therefore shown that the sky over Mauna Kea is
suitable for astronomy at this wavelength under the best conditions. However,
higher or drier sites should have a larger number of useable nights per year.


title: SuperGZK neutrinos

abstract:
  The sources and fluxes of superGZK neutrinos, $E>10^{20}$ eV, are discussed.
The fluxes of {\em cosmogenic neutrinos}, i.e. those produced by ultra-high
energy cosmic rays (UHECR) interacting with CMB photons, are calculated in the
models, which give the good fit to the observed flux of UHECR. The best fit
given in no-evolutionary model with maximum acceleration energy $E_{\rm
max}=1\times 10^{21}$ eV results in very low flux of superGZK neutrinos an
order of magnitude lower than the observed flux of UHECR. The predicted
neutrino flux becomes larger and observable by next generation detectors at
energies $10^{20} - 10^{21}$ eV in the evolutionary models with $E_{\rm
max}=1\times 10^{23}$ eV. The largest cosmogenic neutrino flux is given in
models with very flat generation spectrum, e.g. $\propto E^{-2}$. The neutrino
energies are naturally high in the models of {\em superheavy dark matter and
topological defects}. Their fluxes can also be higher than those of cosmogenic
neutrinos. The largest fluxes are given by {\em mirror neutrinos}, oscillating
into ordinary neutrinos. Their fluxes obey some theoretical upper limit which
is very weak, and in practice these fluxes are most efficiently limited now by
observations of radio emission from neutrino-induced showers.


title:
Dynamics and Non-Gaussianity in the Weak-Dissipative Warm Inflation
  Scenario

abstract:
  We calculate the general solutions for a warm inflationary scenario with weak
dissipation, reviewing the dissipative dynamics of the two-fluid system, and
calculate the bispectrum of the gravitational field fluctuations generated in
the case where dissipation of the vacuum potential during inflation is the
mechanism for structure formation, but is the sub-dominant effect in the
dynamics of the scalar field during slow-roll. The bispectrum is non-zero
because of the self-interaction of the scalar field. We compare the predictions
with both those of standard, or `supercooled', inflationary models, and warm
inflation models with strong dissipation and consider the detectability of
these levels of non-Gaussianity in the bispectrum of the cosmic microwave
background. We find that the levels of non--Gaussianity for warm and
supercooled inflation are an order of magnitude different.


title: Oxygen and Nitrogen in Isolated Dwarf Irregular Galaxies

abstract:
  We present long slit optical spectroscopy of 67 HII regions in 21 dwarf
irregular galaxies to investigate the enrichment of oxygen, nitrogen, neon,
sulfur, and argon in low mass galaxies. Oxygen abundances are obtained via
direct detection of the temperature sensitive emission lines for 25 HII
regions; for the remainder of the sample, oxygen abundances are estimated from
strong line calibrations. The direct abundance determinations are compared to
the strong-line abundance calibrations of both McGaugh (1991) and Pilyugin
(2000). Global oxygen and nitrogen abundances for this sample of dwarf
irregular galaxies are examined in the context of open and closed box chemical
evolution models. While several galaxies are consistent with closed box
chemical evolution, the majority of this sample have an effective yield ~1/4 of
the expected yield for a constant star formation rate and Salpeter IMF,
indicating that either outflow of enriched gas or inflow of pristine gas has
occurred. The effective yield strongly correlates with M_H/L_B in the sense
that gas-rich galaxies are more likely to be closed systems. However, the
effective yield does not appear to correlate with other global parameters such
as dynamical mass, absolute magnitude, star formation rate or surface
brightness. A correlation is found between the observed nitrogen-to-oxygen
ratio and the color of the underlying stellar population; redder dwarf
irregular galaxies have higher N/O ratios than blue dwarf irregular galaxies.
The relative abundance ratios are interpreted in the context of delayed release
of nitrogen and varied star formation histories.


title: Oxygen and Nitrogen in Leo A and GR 8

abstract:
  We present elemental abundances for multiple HII regions in Leo A and GR 8
obtained from long slit optical spectroscopy of these two nearby low luminosity
dwarf irregular galaxies. As expected from their luminosities, and in agreement
with previous observations, the derived oxygen abundances are extremely low in
both galaxies. High signal-to-noise ratio observations of a planetary nebula in
Leo A yield 12 + log(O/H) = 7.30 +/- 0.05; "semi-empirical" calculations of the
oxygen abundance in four HII regions in Leo A indicate 12 + log(O/H) = 7.38 +/-
0.10. These results confirm that Leo A has one of the lowest ISM metal
abundances of known nearby galaxies. Based on results from two HII regions with
high signal-to-noise measurements of the weak [O III] 4363 line, the mean
oxygen abundance of GR 8 is 12 + log(O/H) = 7.65 +/- 0.06; using "empirical"
and "semi-empirical" methods, similar abundances are derived for 6 other GR 8
HII regions. Similar to previous results in other low metallicity galaxies, the
mean log(N/O) = -1.53 +/- 0.09 for Leo A and -1.51 +/- 0.07 for GR 8. There is
no evidence of significant variations in either O/H or N/O in the HII regions.
The metallicity-luminosity relation for nearby (D < 5 Mpc) dwarf irregular
galaxies with measured oxygen abundances has a mean correlation of 12 +
log(O/H) = 5.67 - 0.151 M_B with a dispersion in oxygen about the relationship
of 0.21. These observations confirm that gas-rich low luminosity galaxies have
extremely low elemental abundances in the ionized gas-phase of their
interstellar media. Although Leo A has one of the lowest metal abundances of
known nearby galaxies, detection of tracers of an older stellar population
indicate that it is not a newly formed galaxy as has been proposed for some
other similarly low metallicity star forming galaxies.


title: Tracing the mass profiles of galaxy clusters with member galaxies

abstract:
  The mass distribution of galaxy clusters can be determined from the study of
the projected phase-space distribution of cluster galaxies. The main advantage
of this method as compared to others, is that it allows determination of
cluster mass profiles out to very large radii. Here I review recent analyses
and results on this topic. In particular, I briefly describe the Jeans and
Caustic methods, and the problems one has to face in applying these methods to
galaxy systems. Then, I summarize the most recent and important results on the
mass distributions of galaxy groups, clusters, and superclusters. Additional
covered topics are the relative distributions of the dark and baryonic
components, and the orbits of galaxies in clusters.


title: Stochastic gravitational wave background from cold dark matter halos

abstract:
  The current knowledge of cosmological structure formation suggests that Cold
Dark Matter (CDM) halos possess a nonspherical density profile, implying that
cosmic structures can be potential sources of gravitational waves via power
transfer from scalar perturbations to tensor metric modes in the nonlinear
regime. By means of a previously developed mathematical formalism and a
triaxial collapse model, we numerically estimate the stochastic
gravitational-wave background generated by CDM halos during the fully nonlinear
stage of their evolution. Our results suggest that the energy density
associated with this background is comparable to that produced by primordial
tensor modes at frequencies $\nu\approx10^{-18}-10^{-17}$Hz if the energy scale
of inflation is $V^{1/4}\approx 1-2\times 10^{15}$ GeV, and that these
gravitational waves could give rise to several cosmological effects, including
secondary CMB anisotropy and polarization.


title:
LINER-like Extended Nebulae in ULIRGs: Shocks Generated by Merger
  Induced Flows

abstract:
  In this work we studied the two-dimensional ionization structure of the
circumnuclear and extranuclear regions in a sample of six low-z Ultraluminous
Infrared Galaxies using Integral Field Spectroscopy. The ionization conditions
in the extranuclear regions of these galaxies (~5-15 kpc) are typical of LINERs
as obtained from the Veilleux-Osterbrock line ratio diagnostic diagrams. The
range of observed line ratios is best explained by the presence of fast shocks
with velocities of 150 to 500 km s^{-1}, while the ionization by an AGN or
nuclear starburst is in general less likely. The comparison of the
two-dimensional ionization level and velocity dispersion in the extranuclear
regions of these galaxies shows a positive correlation, further supporting the
idea that shocks are indeed the main cause of ionization.
  The origin of these shocks is also investigated. Despite the likely presence
of superwinds in the circumnuclear regions of these systems, no evidence for
signatures of superwinds such as double velocity components are found in the
extended extranuclear regions. We consider a more likely explanation for the
presence of shocks, the existence of tidally induced large scale gas flows
caused by the merging process itself, as evidenced by the observed velocity
fields characterized by peak-to-peak velocities of 400 km s^{-1}, and velocity
dispersions of up to 200 km s^{-1}.


title: The Durham Micro-Optics Programme

abstract:
  The Durham Microoptics Programme was established to develop key components to
be used for integral field spectrographs for upcoming instrumentation projects,
focussing on currently existing telescopes as well as on the next generation of
ELTs. These activities include monolithic multi-optics machining and grinding,
optical surface improvement using various post polishing techniques and
replication of micro-optical components. While these developments have mostly
slicer-type IFUs in mind, also new types of microlens arrays are in development
for fiber based high contrast IFU systems.


title: Two Dimensional Velocity Fields of Low Surface Brightness Galaxies

abstract:
  We present high resolution two dimensional velocity fields from integral
field spectroscopy along with derived rotation curves for nine low surface
brightness galaxies. This is a positive step forward in terms of both data
quality and number of objects studied. We fit NFW and pseudo-isothermal halo
models to the observations. We find that the pseudo-isothermal halo better
represents the data in most cases than the NFW halo, as the resulting
concentrations are lower than would be expected for LCDM.


title: Optical replication techniques for image slicers

abstract:
  The Smart Focal Planes (SmartFP) activity is a European Joint Research
Activity funded to develop novel optical technologies for future large
telescope instrumentation. In this paper, we will discuss the image slicer
developments being carried out as part of this initiative. Image slicing
technique s have many applications in the plans for instrumentation on
Extremely Large Telescopes and will be central to the delivery of the science
case. A study of a virtual "multi-object multi-ifu spectrograph and imager"
(MOMSI) for a hypothetical OWL-class telescope reveals the need for focal plane
splitting, deployable imagers and very small beam steering elements like
deployable IFUs. The image slicer workpackage, lead from Durham University in
collaboration with LFM Bremen, TNO Delft, UKATC Edinburgh, CRAL Lyon, LAM
Marseille, Padua University and REFLEX Prague, is evaluating technologies for
manufacturing micro optics in large numbers to enable multi-object integral
field spectroscopy.


title: Are Quasar Jets Matter or Poynting Flux Dominated?

abstract:
  If quasar jets are accelerated by magnetic fields but terminate as matter
dominated, where and how does the transition occur between the
Poynting-dominated and matter-dominated regimes? To address this question, we
study constraints which are imposed on the jet structure by observations at
different spatial scales. We demonstrate that observational data are consistent
with a scenario where the acceleration of a jet occurs within 10^{3-4} R_g. In
this picture, the non-thermal flares -- important defining attributes of the
blazar phenomenon - are produced by strong shocks formed in the region where
the jet inertia becomes dominated by matter. Such shocks may be formed due to
collisions between the portions of a jet accelerated to different velocities,
and the acceleration differentiation is very likely to be related to global MHD
instabilities.