title:
High Resolution HI Observations of the Galaxy NGC404: a dwarf S0 with
  abundant Interstellar gas

abstract:
  (Abridged) We present HI maps of the S0 galaxy NGC404, at a spatial
resolution of 15.2" x 14.4" and a velocity resolution of 2.6km/s. The HI has
been traced out to a radius R~8R_25 or 48 disc scale-lengths, making it one of
the largest HI extents reported (800" or 12.6kpc at the assumed distance of
3.3Mpc). Approximately 75% of the HI resides in a doughnut which is seen close
to face-on and the optical galaxy fits snugly within the hole of the doughnut.
The remaining 25% of the neutral gas is found in an annulus concentric with the
doughnut and with a somewhat larger ellipticity. A total HI mass of 1.52 x 10^8
Msol is found, which implies an M(HI)/L_B = 0.22 in solar units. We argue that
most if not all of this gas is of external origin, most likely due to the
merger of a dwarf irregular galaxy with M_B ~ -15.5mag.
  The velocity field shows a steeply declining observed rotation curve,
compatible with Keplerian decline. However, because the galaxy is close to
face-on there is a degeneracy in the determination of the intrinsic rotation
curve and inclination. We therefore analysed two extreme cases, producing
tilted-ring model fits forcing either a Keplerian or a Flat rotation curve
through the observations; both approaches result in equally plausible fits.
  Assuming a distance of 3.3Mpc, a total mass of 3 x 10^10 Msol is found on the
basis of the Keplerian rotation curve. This implies a global M/L_B ratio of ~44
in solar units which is high and likely a reflection of the low blue luminosity
of the galaxy (~15 times lower than the average S0 luminosity). Values for a
Flat rotation curve are a factor of 4 higher.


title: Constraining X-ray Binary Jet Models via Reflection

abstract:
  Although thermal disk emission is suppressed or absent in the hard state of
X-ray binaries, the presence of a cold, thin disk can be inferred from
signatures of reprocessing in the ~2-50 keV band. The strength of this
signature is dependent on the source spectrum and flux impinging on the disk
surface, and is thus very sensitive to the system geometry. The general
weakness of this feature in the hard state has been attributed to either a
truncation of the thin disk, large ionization, or beaming of the corona region
away from the disk with \beta~0.3. This latter velocity is comparable to jet
nozzle velocities, so we explore whether a jet can account for the observed
reflection fractions. It has been suggested that jets may contribute to the
high-energy spectra of X-ray binaries, via either synchrotron from around
100-1000 r_g along the jet axis or from inverse Compton (synchrotron
self-Compton and/or external Compton) from near the base. Here we calculate the
reflection fraction from jet models wherein either synchrotron or Compton
processes dominate the emission. Using as a guide a data set for GX 339-4,
where the reflection fraction previously has been estimated as ~10%, we study
the results for a jet model. We find that the synchrotron case gives < 2%
reflection, while a model with predominantly synchrotron self-Compton in the
base gives ~10-18%. This shows for the first time that an X-ray binary jet is
capable of significant reflection fractions, and that extreme values of the
reflection may be used as a way of discerning the dominant contributions to the
X-ray spectrum.


title: Gravoturbulent Star Cluster Formation

abstract:
  Stars form by gravoturbulent fragmentation of interstellar gas clouds. The
supersonic turbulence ubiquitously observed in Galactic molecular gas generates
strong density fluctuations with gravity taking over in the densest and most
massive regions. Collapse sets in to build up stars and star clusters.
  Turbulence plays a dual role. On global scales it provides support, while at
the same time it can promote local collapse. Stellar birth is thus intimately
linked to the dynamical behavior of parental gas cloud, which determines when
and where protostellar cores form, and how they contract and grow in mass via
accretion from the surrounding cloud material to build up stars. Slow,
inefficient, isolated star formation is a hallmark of turbulent support,
whereas fast, efficient, clustered star formation occurs in its absence.
  The fact that Galactic molecular clouds are highly filamentary can be
explained by a combination of compressional flows and shear. The dynamical
evolution of nascent star clusters is very complex. This strongly influences
the stellar mass spectrum. The equation of state (EOS) plays a pivotal role in
the fragmentation process. Under typical cloud conditions, massive stars form
as part of dense clusters. However, for gas with effective polytropic index
greater than unity star formation becomes biased towards isolated massive
stars, which may be of relevance for understanding Pop III stars.


title:
An emission ring at 20 microns around the HAEBE star AB Aurigae:
  unveiling the disc structure

abstract:
  Isolated HAEBE stars are believed to represent an intermediate stage of
objects between young stellar objects surrounded by massive, optically thick,
gaseous and dusty disks and Vega like stars surrounded by debris disks. The
star AB Aur is already known for being surrounded by an intermediate-stage dust
disk emitting a fairly large infrared and (sub-)millimetric excess. Until now,
the outer disk structure has only been resolved at millimeter wavelengths and
at optical wavelength coronographic imaging. We have obtained 20 microns images
which show an unexpected ellipse-shaped disk structure in emission at a
distance of about 260 AU from the central star. Large azimuthal asymmetries in
brightness can be noticed and the center of the ellipse does not coincide with
the star. A simple, pure geometrical model based on an emission ring of uniform
surface brightness, but having an intrinsic eccentricity succeeds in fitting
the observations. These observations give for the first time clues on a very
peculiar structure of pre-main-sequence disk geometry, i.e. a non uniform
increase in the disk thickness unlike the common usual sketch of a disk with a
constant flaring angle. They provide also valuable informations on the disk
inclination as well as its dust composition; at such a large distance from the
star, only transient heating of very small particles can explain such a bright
ring of emission at mid-infrared wavelengths. Finally, the increase of
thickness inferred by the model could be caused by disk instabilities; the
intrinsic eccentricity of the structure might be a clue to the presence of a
massive body undetected yet.


title: The HCO+ emission excess in bipolar outflows

abstract:
  A plausible model is proposed for the enhancement of the abundance of
molecular species in bipolar outflow sources. In this model, levels of HCO+
enhancement are considered based on previous chemical calculations, that are
assumed to result from shock-induced desorption and photoprocessing of dust
grain ice mantles in the boundary layer between the outflow jet and the
surrounding envelope. A radiative transfer simulation that incorporates
chemical variations within the flow shows that the proposed abundance
enhancements in the boundary layer are capable of reproducing the observed
characteristics of the outflow seen in HCO+ emission in the star forming core
L1527. The radiative transfer simulation also shows that the emission lines
from the enhanced molecular species that trace the boundary layer of the
outflow exhibit complex line profiles indicating that detailed spatial maps of
the line profiles are essential in any attempt to identify the kinematics of
potential infall/outflow sources. This study is one of the first applications
of a full three dimensional radiative transfer code which incorporates chemical
variations within the source.


title: Nonextensivity and Galaxy Clustering in the Universe

abstract:
  We investigate two important questions about the use of the nonextensive
thermostatistics (NETS) formalism in the context of nonlinear galaxy clustering
in the Universe. Firstly, we define a quantitative criterion for justifying
nonextensivity at different physical scales. Then, we discuss the physics
behind the ansatz of the entropic parameter $q(r)$. Our results suggest the
approximate range where nonextensivity can be justified and, hence, give some
support to the applicability of NETS to the study of large scale structures.


title: X-ray aurora in neutron star magnetospheres

abstract:
  In this study we propose a new generic model for QPOs based on oscillation
modes of neutron star magnetospheres. We argue that the interaction of the
accretion disk with the magnetosphere can excite resonant shear Alfven waves in
a region of enhanced density gradients. We demonstrate that depending on the
distance of this enhanced density region from the star and the magnetic field
strength, the frequency of the field line resonance can range from several Hz
(weaker field, farther from star), to approximately kHz frequencies (stronger
field, ~ 2-10 star radii from the star). We show that such oscillations are
able to significantly modulate inflow of matter from the high density region
toward the star surface, and possibly produce the observed X-ray spectrum. In
addition, we show that the observed 2:3 frequency ratio of QPOs is a natural
result of our model.


title: The statistical Analysis of Star Clusters

abstract:
  We review a range of stastistical methods for analyzing the structures of
star clusters, and derive a new measure ${\cal Q}$ which both quantifies, and
distinguishes between, a (relatively smooth) large-scale radial density
gradient and multi-scale (fractal) sub-clustering. Q is derived from the
normalised correlation length and the normalised edge length of the minimal
spanning tree for each cluster.


title: HE 0047-1756: A new gravitationally lensed double QSO

abstract:
  The quasar HE 0047-1756, at z=1.67, is found to be split into two images
1.44" apart by an intervening galaxy acting as a gravitational lens. The flux
ratio for the two components is roughly 3.5:1, depending slightly upon
wavelength. The lensing galaxy is seen on images obtained at 800 nm and 2.1
\mu; there is also a nearby faint object which may be responsible for some
shear. The spectra of the two quasar images are nearly identical, but the
emission line ratio between the two components scale differently from the
continuum. Moreover, the fainter component has a bluer continuum slope than the
brighter one. We argue that these small differences are probably due to
microlensing. There are hints of an Einstein ring emanating from the brighter
image toward the fainter one.


title:
HST/WFPC2 morphologies and color maps of distant luminous infrared
  galaxies

abstract:
  Using HST/WFPC2 imaging in F606W (or F450W) and F814W filters, we obtained
the color maps in observed frame for 36 distant (0.4<z<1.2) luminous infrared
galaxies (LIRGs), with average star formation rates of ~100 M_sun/yr. Stars and
compact sources are taken as references to align images after correction of
geometric distortion. This leads to an alignment accuracy of 0.15 pixel, which
is a prerequisite for studying the detailed color properties of galaxies with
complex morphologies. A new method is developed to quantify the reliability of
each pixel in the color map without any bias against very red or blue color
regions.Based on analyses of two-dimensional structure and spatially resolved
color distribution, we carried out morphological classification for LIRGs.
About 36% of the LIRGs were classified as disk galaxies and 22% as irregulars.
Only 6 (17%) systems are obvious ongoing major mergers. An upper limit of 58%
was found for the fraction of mergers in LIRGs with all the possible
merging/interacting systems included. Strikingly, the fraction of compact
sources is as high as 25%, similar to that found in optically selected samples.
  From their K band luminosities, LIRGs are relatively massive systems, with an
average stellar mass of about 1.1x10^11 solar mass. They are related to the
formation of massive and large disks, from their morphologies and also from the
fact that they represent a significant fraction of distant disks selected by
their sizes. The compact LIRGs show blue cores, which could be associated with
the formation of the central region of these galaxies. We suggest that there
are many massive disks still forming a large fraction of their stellar mass
since z=1. For most of them, their central parts (bulge?) were formed prior to
the formation of their disks.


title:
Extragalactic UHE proton spectrum and prediction for iron-nuclei flux at
  10^8 - 10^9 GeV

abstract:
  We investigate the problem of transition from Galactic cosmic rays to
extragalactic ultra high energy cosmic rays. Using the model for extragalactic
ultra high energy cosmic rays and observed all-particle cosmic ray spectrum, we
calculate the galactic spectrum of iron nuclei in the energy range $10^8 -
10^9$ GeV. The flux and spectrum predicted at lower energies agree well with
the KASCADE data. The transition from Galactic to extragalactic cosmic rays is
distinctly seen in spectra of protons and iron nuclei, when they are measured
separately. The shape of predicted iron spectrum agrees with the Hall
diffusion.


title: Galaxy Kinematics with SALT

abstract:
  The combination of dynamical and photometric properties of galaxies offers a
largely un-tapped source of information on how galaxies assembled and where
stars formed. Bi-dimensional kinematic measurements have been the stumbling
block. The light-gathering power of SALT coupled with the high-throughput
performance of the Prime Focus Imaging Spectrograph (PFIS) yield a superb
facility for measuring velocity-ellipsoids of stars and gas in galaxies out to
gigaparsec distances. From these data dynamical asymmetries arising from
lopsided or elliptical halos may be probed; disk-mass and mass-decompositions
may be uniquely determined; mechanisms for disk heating constrained; and a
zeropoint for the mass-to-light ratios of stellar populations set. A number of
groups within the SALT consortium are interested in making these measurements
using a variety of different, but complementary approaches. The scientific
potential from their synthesis is very promising. We describe some unusual
observational modes in which PFIS may be used to probe the shape of dark-matter
halos and the content of galaxy disks.


title: High energy emission from IGR J16320-4751

abstract:
  IGR J16320-4751 was re-discovered by IBIS/ISGRI on board INTEGRAL in early
February 2003 during the observation of the black hole candidate 4U 1630-47 (PI
Tomsick). This source, already observed by ASCA and BeppoSAX, belongs to the
class of heavily absorbed objects (N_H > 10^23 cm^-2) that populate some arms
of the Galaxy. Soon after the rediscovery by IBIS/ISGRI, the source was
observed by XMM-Newton: the arcsec position found with XMM allowed ones to find
the most likely infrared counterpart. We present here the reanalysis of the
high energy emission from IGR J16320-4751 detected by IBIS/ISGRI, including the
spectral and temporal characteristics. We also present a reanalysis of the
XMM-Newton and optical/IR data.


title: Approaching Lambda without fine-tuning

abstract:
  We address the fine-tuning problem of dark energy cosmologies which arises
when the dark energy density needs to initially lie in a narrow range in order
for its present value to be consistent with observations. As recently noticed,
this problem becomes particularly severe in canonical Quintessence scenarios,
when trying to reproduce the behavior of a cosmological constant, i.e. when the
dark energy equation of state w_Q approaches -1: these models may be reconciled
with a large basin of attraction only by requiring a rapid evolution of w_Q at
low reshifts, which is in conflict with the most recent estimates from type Ia
Supernovae discovered by Hubble Space Telescope. Next, we focus on
scalar-tensor theories of gravity, discussing the implications of a coupling
between the Quintessence scalar field and the Ricci scalar (``Extended
Quintessence''). We show that, even if the equation of state today is very
close to -1, by virtue of the scalar-tensor coupling the quintessence
trajectories still possess the attractive feature which allows to reach the
present level of cosmic acceleration starting by a set of initial conditions
which covers tens of orders of magnitude; this effect, entirely of
gravitational origin, represents a new important consequence of the possible
coupling between dark energy and gravity.


title: Hard X-ray sky survey with the SIGMA telescope aboard GRANAT observatory

abstract:
  During the lifetime of GRANAT orbital observatory the SIGMA telescope
collected X-ray images of more than 1/4 of the whole sky. Among these regions
the Galactic Center had largest exposure time (~9 million sec). In the present
work we review all observations of the SIGMA telescope and present
sensitivities achieved with it at different sky regions


title: Discovery of a WO star in the Scutum-Crux arm of the inner Galaxy

abstract:
  We report the discovery of only the fourth massive WO star to be found in the
Milky Way, and only the seventh identified within the Local Group. This has
resulted from the first observations made in a programme of follow-up
spectroscopy of candidate emission line stars from the AAO/UK Schmidt Southern
Galactic Plane H-alpha Survey. The optical spectrum of this star, to become WR
93b in the Catalogue of Galactic Wolf-Rayet stars, is presented and described.
WR 93b is classified as WO3 and is shown to be highly reddened (E(B-V) = 2.1 pm
0.1). A recombination line analysis of the emission lines yields the abundance
ratios C/He = 0.95 and O/He = 0.13 (by number). Comparisons at near infrared
wavelengths of reddening corrected photometry between WR 93b and both of Sand 2
(WO3, D = 49 kpc) and Sand 5 (WO2, D = 1.75 kpc) yields a consistent distance
to WR 93b of 3.4 kpc. Positioned at Galactic co-ordinates l = 353.27, b =
-0.85, the star is most likely located in the Scutum-Crux Arm of the inner
Milky Way. We note that none of the four Galactic WO stars lies significantly
beyond the Solar Circle (with two well inside). Estimation of the wind terminal
velocity in WR 93b at 5750 km/s makes this star the current wind speed record
holder among all non-degenerate stars.


title: New light on the S235A-B star forming region

abstract:
  The S235A-B star forming region has been extensively observed in the past
from the radio to the near-IR, but what was happening in the immediate
surroundings of the water maser, placed in between the two nebulosities, was
still unclear because of insufficient resolution especially in the spectral
range from the Far-IR to the mm, even though there were sound indications that
new young stellar objects (YSOs) are being formed there. We present here new
high resolution maps at mm wavelengths in different molecules (HCO+, C34S,
H2CS, SO2 and CH3CN), as well as in the 1.2 and 3.3 mm continuum obtained with
the Plateau de Bure interferometer, and JCMT observations at 450 micron and 850
micron that unambiguously reveal the presence of new YSOs placed in between the
two HII regions S235A and S235B and associated with the water maser. A
molecular core and an unresolved source in the mm and in the sub-mm are centred
on the maser, with indication of mass infall onto the core. Two molecular
bipolar outflows and a jet originate from the same position. Weak evidence is
found for a molecular rotating disk perpendicular to the direction of the main
bipolar outflow. The derived parameters indicate that one of the YSOs is an
intermediate luminosity object (L~1000 Lsun) in a very early evolutionary
phase, embedded in a molecular core of ~100 Msun, with a temperature of 30 K.
The main source of energy for the YSO could come from gravitational infall,
thus making of this YSO a rare example of intermediate luminosity protostar
representing a link between the earliest evolutionary phases of massive stars
and low mass protostars of class 0-I.


title: Field E+A Galaxies at Intermediate Redshifts (0.3<z<1)

abstract:
  We select E+A candidates from a spectroscopic dataset of ~800 field galaxies
and measure the E+A fraction at 0.3<z<1 to be 2.7+/-1.1%, a value lower than
that in galaxy clusters at comparable redshifts (11+/-3%). HST/WFPC2 imaging
for five of our six E+A's shows they have a heterogeneous parent population:
these E+A's span a range in half-light radius (0.8-8 kpc) and estimated
internal velocity dispersion (50-220 km/s), and they include luminous systems
(-21.6<M_Bz-5logh<-19.2). Despite their diversity in some aspects, the E+A's
share several common characteristics that indicate the E+A phase is an
important link in the evolution of star-forming galaxies into passive systems:
the E+A's are uniformly redder than the blue, star-forming galaxies that make
up the majority of the field, they are more likely to be bulge-dominated than
the average field galaxy, and they tend to be morphologically irregular. We
find E+A's make up ~9% of the absorption line systems in this redshift range,
and estimate that ~25% of passive galaxies in the local field had an E+A phase
at z<1.


title: Constraining solar abundances using helioseismology

abstract:
  Recent analyses of solar photospheric abundances suggest that the oxygen
abundance in the solar atmosphere needs to be revised downwards. In this study
we investigate the consequence of this revision on helioseismic analyses of the
depth of the solar convection zone and the helium abundance in the solar
envelope and find no significant effect. We also find that the revised
abundances along with the current OPAL opacity tables are not consistent with
seismic data. A significant upward revision of the opacity tables is required
to make solar models with lower oxygen abundance consistent with seismic
observations.


title:
Spectroscopic Properties of Cool Stars in the SDSS: An Analysis of
  Magnetic Activity and a Search for Subdwarfs

abstract:
  We present a spectroscopic analysis of nearly 8000 late-type dwarfs in the
Sloan Digital Sky Survey. Using the Halpha emission line as an activity
indicator, we investigate the fraction of active stars as a function of
spectral type and find a peak near type M8, confirming previous results. In
contrast to past findings, we find that not all M7-M8 stars are active. We show
that this may be a selection effect of the distance distributions of previous
samples, as the active stars appear to be concentrated near the Galactic Plane.
We also examine the activity strength (ratio of the luminosity emitted in
Halpha to the bolometric luminosity) for each star, and find that the mean
activity strength is constant over the range M0-M5 and declines at later types.
The decline begins at a slightly earlier spectral type than previously found.
We explore the effect that activity has on the broadband photometric colors and
find no significant differences between active and inactive stars. We also
carry out a search for subdwarfs using spectroscopic metallicity indicators,
and find 60 subdwarf candidates. Several of these candidates are near the
extreme subdwarf boundary. The spectroscopic subdwarf candidates are redder by
\~0.2 magnitudes in g-r compared to disk dwarfs at the same r-i color.


title:
Electron Acceleration around the Supermassive Black Hole at the Galactic
  Center

abstract:
  The recent detection of variable infrared emission from Sagittarius A*,
combined with its previously observed flare activity in X-rays, provides
compelling evidence that at least a portion of this object's emission is
produced by nonthermal electrons. We show here that acceleration of electrons
by plasma wave turbulence in hot gases near the black hole's event horizon can
account both for Sagittarius A*'s mm and shorter wavelengths emission in the
quiescent state, and for the infrared and X-ray flares, induced either via an
enhancement of the mass accretion rate onto the black hole or by a
reorganization of the magnetic field coupled to the accretion gas. The
acceleration model proposed here produces distinct flare spectra that may be
compared with future coordinated multi-wavelength observations. We further
suggest that the diffusion of high energy electrons away from the acceleration
site toward larger radii might be able to account for the observed
characteristics of Sagittarius A*'s emission at cm and longer wavelengths.


title:
On the nature of the flux variability during an expansion stage of a
  type I X-ray burst: Constraints on Neutron Star Parameters for 4U 1820-30

abstract:
  Powerful Type I X-ray burst with strong radial expansion was observed from
the low mass X-ray binary 4U 1820-30 with Rossi X-ray Timing Explorer on May 2,
  1997. We investigate closely the flux profile during the burst expansion
stage. Applying a semi-analytical model we are able to uncover the behavior of
a photospheric radius and to simulate the evolution of neutron star
(NS)-accretion disk system. The bottom flux L_{bot} is a few times the
Eddington limit L_{Edd} for outer layers, because the electron cross-section is
a few times less than the Thomson cross-section at such a high temperatures.
The surplus of energy flux with respect to the Eddington, $L_{bot}-L_{Edd}$,
goes into the potential energy of the expanded envelope. As cooling of the
burning zone starts the surplus decreases and thus the envelope shrinks while
the emergent photon flux stays the same $L=L_{Edd}$. At a certain moment the NS
low-hemisphere, previously screened by the disk, becomes visible to the
observer. Consequently, the flux detected by the observer increases. Indeed, we
observe to the paradoxical situation when the burning zone cools, but the
apparent flux increases because of the NS-accretion disk geometry. We
demonstrate a strong observational evidence of NS-accretion disk occultation in
the behavior of the observed bolometric flux. We estimate the anisotropy due to
geometry and find that the system should have a high inclination angle.
Finally, we apply an analytical model of X-ray spectral formation in the
neutron star atmosphere during burst decay stage to infer the neutron star (NS)
mass-radius relation.


title: Properties of neutron stars

abstract:
  I review attempts made to determine the properties of neutron stars. I focus
on constraints on the maximum mass that a neutron star can have, and on
attempts to measure neutron-star radii. So far, there appears to be only one
neutron star for which there is strong evidence that its mass is above the
canonical 1.4 Msun, viz., Vela X-1, for which a mass close to 1.9 Msun is
found. Prospects for progress appear brightest for studies of systems in which
the neutron star should have accreted substantial amounts of matter. While for
individual systems the evidence that neutron stars can have high masses is
weak, the ensemble appears to show that masses around 1.6 Msun are possible.
For the radius determination, most attempts have focussed on neutron stars in
low-mass X-ray binaries in which accretion has temporarily shut down. These
neutron stars are easiest to model, since they should have pure Hydrogen
atmospheres and low magnetic fields. To obtain accurate radii, however,
requires precise distances and very high quality data.


title:
The Spitzer Space Telescope First-Look Survey: KPNO MOSAIC-1 R-band
  Images and Source Catalogs

abstract:
  (Abridged) We present R-band images covering more than 11 square degrees of
sky obtained with the KPNO 4-m telescope in preparation for the Spitzer Space
Telescope First Look Survey. The FLS was designed to characterize the
mid-infrared sky at depths 2 orders of magnitude deeper than previous surveys.
The extragalactic component is the first cosmological survey done with Spitzer.
Two relatively large regions of the sky were observed: the main FLS extra
galactic field (17h18m+59d30m) and ELAIS-N1 field (16h10m+54d30m).
  The overall quality of the images is high. The relative astrometric accuracy
is better than 0.1'' and the typical seeing is 1.1''. Images are relatively
deep since they reach a median 5-sigma depth limiting magnitude of R=25.5
(Vega). Catalogs have been extracted using SExtractor using thresholds in area
and flux for which the number of false detections is below 1% at R=25. Only
sources with S/N greater than 3 have been retained in the final catalogs.
Comparing the galaxy number counts from our images with those of deeper R-band
surveys, we estimate that our observations are 50% complete at R=24.5. These
limits in depth are sufficient to identify a substantial fraction of the
infrared sources which will be detected by Spitzer.


title:
Near-Infrared Molecular Hydrogen Emission from the Central Regions of
  Galaxies: Regulated Physical Conditions in the Interstellar Medium

abstract:
  The central regions of many interacting and early-type spiral galaxies are
actively forming stars. This process affects the physical and chemical
properties of the local interstellar medium as well as the evolution of the
galaxies. We observed near-infrared H2 emission lines: v=1-0 S(1), 3-2 S(3),
1-0 S(0), and 2-1 S(1) from the central ~1 kpc regions of the archetypical
starburst galaxies, M82 and NGC 253, and the less dramatic but still vigorously
star-forming galaxies, NGC 6946 and IC 342. Like the far-infrared continuum
luminosity, the near-infrared H2 emission luminosity can directly trace the
amount of star formation activity because the H2 emission lines arise from the
interaction between hot and young stars and nearby neutral clouds. The observed
H2 line ratios show that both thermal and non-thermal excitation are
responsible for the emission lines, but that the great majority of the
near-infrared H2 line emission in these galaxies arises from energy states
excited by ultraviolet fluorescence. The derived physical conditions, e.g.,
far-ultraviolet radiation field and gas density, from [C II] and [O I] lines
and far-infrared continuum observations when used as inputs to
photodissociation models, also explain the luminosity of the observed H2 v=1-0
S(1) line. The ratio of the H2 v=1-0 S(1) line to far-IR continuum luminosity
is remarkably constant over a broad range of galaxy luminosities; L_H2/L_FIR =
about 10^{-5}, in normal late-type galaxies (including the Galactic center), in
nearby starburst galaxies, and in luminous IR galaxies (LIRGs: L_FIR > 10^{11}
L_sun). Examining this constant ratio in the context of photodissociation
region models, we conclude that it implies that the strength of the incident UV
field on typical molecular clouds follows the gas density at the cloud surface.


title:
Causal configurations of homogeneous energy density in general
  relativity

abstract:
  If the causality condition [the speed of sound always remains less than that
of light in vacuum, i. e., $v \leq c = 1$] is imposed on the spheres of
homogeneous energy density, the `ratio of the specific heats', $\gamma \leq
2.59457$, constraints the compaction parameter, $u [\equiv (M/a)$, mass to size
ratio in geometrized units] of the dynamically stable configurations $ \leq
0.34056 $ [corresponding to a surface redshift $(z_a) \leq 0.771$]. Apparently,
The maximum value of $u$ obtained in this manner belongs to an absolute upper
bound, and gives: (i) The maximum value for static neutron star masses as $5.4
M_\odot$, if we substitute the density at the surface of the configuration
equal to the average nuclear density, $E = 2 \times 10^{14}$ g cm$^{-3}$ [e.g.
{\it Nature}, {\bf 259}, 377 (1976)]. (ii) However, if the density of the
static configuration is constrained to the value $1.072 \times 10^{14}$ g
cm$^{-3}$, by imposing the empirical result that the minimum rotation period of
the fastest rotating pulsar known to date, PSR 1937 + 21, is 1.558 ms, the
maximum mass value for static neutron stars exceed upto $7.4 M_\odot$. These
masses have important implications for the massive compact objects like Cyg
X-1, Cyg XR-1, and LMC-X3 etc., which may not, necessarily, represent black
holes. (iii) The minimum rotation periods for a static $1.442 M_\odot$ neutron
star to be 0.3041 ms. (iv) A suitable stable model of ultra-compact objects [$u
> (1/3)$] which has important astrophysical significance.


title:
Antenna Instrumental Polarization and its Effects on E- and B-Modes for
  CMBP Observations

abstract:
  We analyze the instrumental polarization generated by the antenna system
(optics and feed horn) due to the unpolarized sky emission. Our equations show
that it is given by the convolution of the unpolarized emission map
$T_b(\theta, \phi)$ with a sort of instrumental polarization beam $\Pi$ defined
by the co- and cross-polar patterns of the antenna. This result is general, it
can be applied to all antenna systems and is valid for all schemes to detect
polarization, like correlation and differential polarimeters. The axisymmetric
case is attractive: it generates an $E$-mode--like $\Pi$ pattern, the
contamination does not depend on the scanning strategy and the instrumental
polarization map does not have $B$-mode contamination, making axisymmetric
systems suitable to detect the faint $B$-mode signal of the Cosmic Microwave
Background Polarization. The $E$-mode of the contamination only affects the
FWHM scales leaving the larger ones significantly cleaner. Our analysis is also
applied to the SPOrt experiment where we find that the contamination of the
$E$-mode is negligible in the $\ell$-range of interest for CMBP large angular
scale investigations (multipole $\ell < 10$).


title: High-redshift QSOs in the GOODS

abstract:
  The Great Observatories Origins Deep Survey provides significant constraints
on the space density of less luminous QSOs at high redshift, which is
particularly important to understand the interplay between the formation of
galaxies and super-massive black holes and to measure the QSO contribution to
the UV ionizing background. We present the results of a search for high-z QSOs,
identified in the two GOODS fields on the basis of deep imaging in the optical
(with HST) and X-ray (Chandra), and discuss the allowed space density of QSOs
in the early universe.


title:
Variation in Emission and Absorption Lines and Continuum Flux by Orbital
  Phase in Vela X-1

abstract:
  High resolution spectral studies were undertaken at orbital phases 0, 0.25
and 0.5 on the high-mass X-ray binary (HMXB) Vela X-1 using archival Chandra
data. We present (a) the first detailed analysis of the multiple strong narrow
emission lines present in phase 0.5 (b) an analysis of the absorption of the
continuum in phase 0.5, and (c) the first detection of narrow emission and
absorption lines in phase 0.25. Multiple fluorescent and H-and He-like emission
lines in the band 1.6 - 20 Angstrom in eclipse are partially obscured at phase
0.25 by the X-ray continuum. The phase 0.25 spectrum displays 3 triplets, 2
with a blue-shifted resonance (r) line in absorption and the intercombination
(i) and forbidden (f) lines in emission, and shows in absorption other
blue-shifted lines seen in emission in eclipse. At phase 0.5 the soft X-ray
continuum diminishes revealing an "eclipse-like" spectrum, however line flux
values are around 13-fold those in eclipse. We conclude the narrow emission
lines in Vela X-1 become apparent when the continuum is blocked from line of
sight, either by eclipse or by scattering and/or absorption from a wake or
cloud. The H-and He-like lines arise in warm photoionised regions in the
stellar wind, while the fluorescent lines (including a Ni K alpha line) are
produced in cooler clumps of gas outside these regions. Absorption of the 5-13
Angstrom continuum at phase 0.5 may be caused by an accretion wake comprised of
dense stagnant photoionized plasma inside a Stromgren zone. Multiple
fluorescent emission lines may be a common feature of the supergiant category
of HMXBs.


title: Dissipation of Magnetic Flux in Primordial Gas Clouds

abstract:
  We report the strength of seed magnetic flux of accretion disk surrounding
the PopIII stars. The magnetic field in accretion disk might play an important
role in the transport of angular momentum because of the turbulence induced by
Magneto-Rotational Instability (MRI). On the other hand, since the primordial
star-forming clouds contain no heavy elements and grains, they experience much
different thermal history and different dissipation history of the magnetic
field in the course of their gravitational contraction, from those in the
present-day star-forming molecular clouds. In order to assess the magnetic
field strength in the accretion disk of PopIII stars, we calculate the thermal
history of the primordial collapsing clouds, and investigate the coupling of
magnetic field with primordial gas. As a result, we find that the magnetic
field strongly couple with primordial gas cloud throughout the collapse, i.e.
the magnetic field are frozen to the gas as far as initial field strength
satisfies $ B\lesssim 10^{-5}(n_{\rm H}/10^3{\rm cm^{-3}})^{0.55}{\rm G}$.


title:
VLTI/VINCI observations of the nucleus of NGC 1068 using the adaptive
  optics system MACAO

abstract:
  We present the first near-infrared K-band long-baseline interferometric
measurement of the prototype Seyfert 2 galaxy NGC 1068 with resolution lambda/B
\~ 10 mas obtained with the Very Large Telescope Interferometer (VLTI) and the
two 8.2m Unit Telescopes UT2 and UT3. The adaptive optics system MACAO was
employed to deliver wavefront-corrected beams to the K-band commissioning
instrument VINCI. A squared visibility amplitude of 16.3 +/- 4.3 % was measured
for NGC 1068 at a sky-projected baseline length of 45.8 m and azimuth angle
44.9 deg. This value corresponds to a FWHM of the K-band intensity distribution
of 5.0 +/- 0.5 mas (0.4 +/- 0.04 pc) at the distance of NGC 1068) if it
consists of a single Gaussian component. Taking into account K-band speckle
interferometry observations (Wittkowski et al. 1998; Weinberger et al. 1999;
Weigelt et al. 2004), we favor a multi-component model for the intensity
distribution where a part of the flux originates from scales clearly smaller
than about 5 mas (<0.4 pc), and another part of the flux from larger scales.
The K-band emission from the small (< 5 mas) scales might arise from
substructure of the dusty nuclear torus, or directly from the central accretion
flow viewed through only moderate extinction.


title:
Feedback and Formation of Massive Star Clusters in Giant Molecular
  Clouds

abstract:
  It is well known that the energy input from massive stars dominates the
thermal and mechanical heating of typical regions in the interstellar medium of
galaxies. These effects are amplified tremendously in the immediate environment
of young massive star clusters, which may contain thousands of O and B stars.
We present models of star cluster formation that attempt to account for the
interplay between feedback and self-gravity in forming clusters, with
application to systems ranging from the Orion Nebula Cluster, the Galactic
Center clusters like the Arches, and super star clusters.


title:
Far-Ultraviolet Spectroscopy of Star-Forming Regions in Nearby Galaxies:
  Stellar Populations and Abundance Indicators

abstract:
  We present FUSE spectroscopy and supporting data for star-forming regions in
nearby galaxies, to examine their massive-star content and explore the use of
abundance and population indicators in this spectral range for high-redshift
galaxies. New far-ultraviolet spectra are shown for four bright H II regions in
M33 (NGC 588, 592, 595, and 604), the H II region NGC 5461 in M101, and the
starburst nucleus of NGC 7714, supplemented by the very-low-metallicity galaxy
I Zw 18. In each case, we see strong Milky Way absorption systems from H2, but
intrinsic absorption within each galaxy is weak or undetectable, perhaps
because of the "UV bias" in which reddened stars which lie behind
molecular-rich areas are also heavily reddened. We see striking changes in the
stellar-wind lines from these populations with metallicity, suggesting that C
II, C III, C IV, N II, N III, and P V lines are potential tracers of stellar
metallicity in star-forming galaxies. Three of these relations - involving N
IV, C III, and P V - are nearly linear over the range from O/H=0.05--0.8 solar.
The major difference in continuum shapes among these systems is that the giant
H II complex NGC 604 has a stronger continuum shortward of 950 A than any other
object in this sample. Small-number statistics would likely go in the other
direction; we favor this as the result of a discrete star-forming event ~3 Myr
ago, as suggested by previous studies of its stellar population. (Supported by
NASA grant NAG5-8959)


title: Accretion dynamics in neutron star black hole binaries

abstract:
  We perform three-dimensional, Newtonian hydrodynamic simulations with a
nuclear equation of state to investigate the accretion dynamics in neutron star
black hole systems. We find as a general result that non-spinning donor stars
yield larger circularization radii than corotating donors. Therefore, the
matter from a neutron star without spin will more likely settle into an
accretion disk outside the Schwarzschild radius. With the used stiff equation
of state we find it hard to form an accretion disk that is promising to launch
a gamma-ray burst. In all relevant cases the core of the neutron star survives
and keeps orbiting the black hole as a mini neutron star for the rest of the
simulation time (up to several hundred dynamical neutron star times scales).
The existence of this mini neutron star leaves a clear imprint on the
gravitational wave signal which thus can be used to probe the physics at
supra-nuclear densities.


title:
The 6dF Galaxy Survey: Samples, Observational Techniques and the First
  Data Release

abstract:
  The 6dF Galaxy Survey (6dFGS) aims to measure the redshifts of around 150,000
galaxies, and the peculiar velocities of a 15,000-member sub-sample, over
almost the entire southern sky. When complete, it will be the largest redshift
survey of the nearby universe, reaching out to about z ~ 0.15, and more than an
order of magnitude larger than any peculiar velocity survey to date. The
targets are all galaxies brighter than K_tot = 12.75 in the 2MASS Extended
Source Catalog (XSC), supplemented by 2MASS and SuperCOSMOS galaxies that
complete the sample to limits of (H, J, r_F, b_J) = (13.05, 13.75, 15.6,
16.75). Central to the survey is the Six-Degree Field (6dF) multi-fibre
spectrograph, an instrument able to record 150 simultaneous spectra over the
5.7-degree field of the UK Schmidt Telescope. An adaptive tiling algorithm has
been employed to ensure around 95% fibering completeness over the 17046 sq.deg
of the southern sky with | b | > 10 deg. Spectra are obtained in two
observations using separate V and R gratings, that together give R ~ 1000 over
at least 4000 -- 7500 Angstroms and signal-to-noise ratio ~10 per pixel. The
6dFGS database is available at http://www-wfau.roe.ac.uk/6dFGS/, with public
data releases occuring after the completion of each third of the survey.


title: The Tiling Algorithm for the 6dF Galaxy Survey

abstract:
  The Six Degree Field Galaxy Survey (6dFGS) is a spectroscopic survey of the
southern sky, which aims to provide positions and velocities of galaxies in the
nearby Universe. We present here the adaptive tiling algorithm developed to
place 6dFGS fields on the sky, and allocate targets to those fields. Optimal
solutions to survey field placement are generally extremely difficult to find,
especially in this era of large-scale galaxy surveys, as the space of available
solutions is vast (2N dimensional) and false optimal solutions abound. The
6dFGS algorithm utilises the Metropolis (simulated annealing) method to
overcome this problem. By design the algorithm gives uniform completeness
independent of local density, so as to result in a highly complete and uniform
observed sample. The adaptive tiling achieves a sampling rate of approximately
95%, a variation in the sampling uniformity of less than 5%, and an efficiency
in terms of used fibres per field of greater than 90%. We have tested whether
the tiling algorithm systematically biases the large-scale structure in the
survey by studying the two-point correlation function of mock 6dF volumes. Our
analysis shows that the constraints on fibre proximity with 6dF lead to
under-estimating galaxy clustering on small scales (< 1 Mpc) by up to ~20%, but
that the tiling introduces no significant sampling bias at larger scales.


title:
Comment on ``Strangelets as Cosmic Rays beyond the
  Greisen-Zatsepin-Cuzmin Cutoff''

abstract:
  Madsen and Larsen proposed (astro-ph/0211597) that strangelets - stable lumps
of strange quark matter (SQM) - are candidates for the highest energy cosmic
rays. They point out that the expected properties of strangelets make them
easier to accelerate and less prone to energy losses than protons or ions. The
purpose of this Comment is to point out that if ultra-high-energy cosmic rays
(UHECRs) are indeed strangelets, their flux would guarantee that all neutron
stars must be strange quark (SQ) stars, while no ``conventional'' (i.e.,
composed of nucleons and other baryons) neutron stars can coexist. This seems
highly unlikely in view of various observed phenomena in neutron stars.


title:
Prospects for multiwavelength polarization observations of GRB
  afterglows and the case GRB 030329

abstract:
  We explore the prospects for simultaneous, broad-band, multiwavelength
polarimetric observations of GRB afterglows. We focus on the role of cosmic
dust in GRB host galaxies on the observed percentage polarization of afterglows
in the optical/near-infrared bands as a function of redshift. Our driving point
is the afterglow of GRB 030329, for which we obtained polarimetric data in the
R band and K band simultaneously about 1.5 days after the burst. We argue that
polarimetric observations can be very sensitive to dust in a GRB host, because
dust can render the polarization of an afterglow wavelength-dependent. We
discuss the consequences for the interpretation of observational data and
emphasize the important role of very early polarimetric follow-up observations
in all bands, when afterglows are still bright, to study the physical
properties of dust and magnetic fields in high-z galaxies.


title: Hard X-ray emission from Serpens X-1 as observed by INTEGRAL

abstract:
  We here report results of an INTEGRAL observation of the X-ray burst and
atoll source Ser X-1 performed on May 2003. The object was observed for a total
of 400 ks but nearly 8 degrees off-axis due to the amalgamation with an
observation of SS 433, the pointing target source. Ser X-1 was detected up to
30 keV with unprecedented positional accuracy for a high-energy emission; a
sharp spectral drop is evident beyond this energy. Significant variability is
seen in the 20-30 keV light curve. Comparison with previous observations
indicates that the source was in its high (banana) state and displayed a soft
spectrum during the INTEGRAL pointing. A (non simultaneous) broadband
radio-to-gamma-rays broad-band spectral energy distribution for Ser X-1 is also
presented for the first time.


title: v_\perp CMD

abstract:
  I present an Hipparcos color-magnitude diagram (CMD) that is color-coded by
transverse velocity v_\perp. This illustrates the connection between the
photometric and kinematic properties of various stellar populations in a manner
that is particularly suitable to introductory astronomy courses.


title:
Constraints for the accretion disk evaporation rate in AGN from the
  existence of the Broad Line Region

abstract:
  We analyze the consequences of the hypothesis that the formation of the Broad
Line Region is intrinsically connected with the existence of the cold accretion
disk. We assume that the Broad Line Region radius is well estimated by the
formula of Kaspi et al. (2000). We consider three models of the disappearance
of the inner disk which limit the existence of the Broad Line Region: (i)
classical ADAF approach, i.e. the inner hot flow develops whenever it can exist
(ii) disk evaporation model of Meyer & Meyer-Hofmeister (2002) (iii)
generalized disk evaporation model of Rozanska & Czerny (2000b). For each of
the models, we determine the minimum value of the Eddington ratio and the
maximum value of the broad line widths as functions of the viscosity parameter
alpha and the magnetic field parameter beta. We compare the predicted parameter
space with observations of several AGN. Weak dependence of the maximum value of
the FWHM and minimum value of the Eddington ratio on the black hole mass in our
sample is noticeable. It seems to favor the description of the cold disk/hot
inner flow transition as in the classical ADAF approach than with the model of
disk evaporation due to conduction between the disk and accreting corona.


title: Curvature Effects in Gamma Ray Burst Colliding Shells

abstract:
  An elementary kinematic model for emission produced by relativistic spherical
colliding shells is studied. The case of a uniform blast-wave shell with jet
opening angle $\theta_j \gg 1/\Gamma$ is considered, where $\Gamma$ is the
Lorentz factor of the emitting shell. The shell, with comoving width $\Delta
r^\prime$, is assumed to be illuminated for a comoving time $\Delta t^\prime$
and to radiate a broken power-law $\nu L_\nu$ spectrum peaking at comoving
photon energy $\e_{pk,0}^{\prime}$. Synthetic GRB pulses are calculated, and
the relation between energy flux and internal comoving energy density is
quantified. Curvature effects dictate that the measured $\nu F_\nu$ flux at the
measured peak photon energy $\e_{pk}$ is proportional to $\e^3_{pk}$ in the
declining phase of a GRB pulse. Possible reasons for discrepancy with
observations are discussed, including adiabatic and radiative cooling processes
that extend the decay timescale, a nonuniform jet, or the formation of pulses
by external shock processes. A prediction of a correlation between prompt
emission properties and times of the optical afterglow beaming breaks is made
for a cooling model, which can be tested with Swift.


title:
The case against the progenitor's carbon-to-oxygen ratio as a source of
  peak luminosity variations in Type Ia supernovae

abstract:
  One of the major challenges for theoretical modeling of Type Ia supernova
explosions is to explain the diversity of these events and the empirically
established correlation between their peak luminosity and light curve shape. In
the framework of the so-called Chandrasekhar mass models, the progenitor's
carbon-to-oxygen ratio has been suggested to be a principal source of peak
luminosity variations due to a variation in the production of radioactive
$^{56}$Ni during the explosion. The underlying idea is that an enhanced carbon
mass fraction should result in a more vigorous explosion since here the energy
release from nuclear reactions is increased. It was suspected that this would
produce a higher amount of $^{56}$Ni in the ejecta. In this letter we describe
a mechanism resulting from an interplay between nucleosynthesis and turbulent
flame evolution which counteracts such an effect. Based on three-dimensional
simulations we argue that it is nearly balanced and only minor differences in
the amount of synthesized $^{56}$Ni with varying carbon mass fraction in the
progenitor can be expected. Therefore this progenitor parameter is unlikely to
account for the observed variations in Type Ia supernova luminosity. We discuss
possible effects on the calibration of cosmological measurements.


title:
Discovery of a supernova associated with GRB 031203: SMARTS
  Optical-Infrared Lightcurves from 0.2 to 92 days

abstract:
  Optical and infrared monitoring of the afterglow site of gamma-ray burst
(GRB) 031203 has revealed a brightening source embedded in the host galaxy,
which we attribute to the presence of a supernova (SN) related to the GRB ("SN
031203"). We present details of the discovery and evolution of SN 031203 from
0.2 to 92 days after the GRB, derived from SMARTS consortium photometry in I
and J bands. A template type Ic lightcurve, constructed from SN 1998bw
photometry, is consistent with the peak brightness of SN 031203 although the
lightcurves are not identical. Differential astrometry reveals that the SN, and
hence the GRB, occurred less than 300 h_71^-1 pc (3-sigma) from the apparent
galaxy center. The peak of the supernova is brighter than the optical afterglow
suggesting that this source is intermediate between a strong GRB and a
supernova.


title: Fast Growth of Supermassive Black Holes in Galaxies

abstract:
  We report on a calculation of the growth of the mass of supermassive black
holes at galactic centers from dark matter and Eddington - limited baryonic
accretion. Assuming that dark matter halos are made of fermions and harbor
compact degenerate Fermi balls of masses from $10^{3}M_{\odot}$ to
$10^{6}M_{\odot}$, we find that dark matter accretion can boost the mass of
seed black holes from about $\sim 5M_{\odot}$ to $10^{3-4}M_{\odot}$ black
holes, which then grow by Eddington - limited baryonic accretion to
supermassive black holes of $10^{6 - 9}M_{\odot}$. We then show that the
formation of the recently detected supermassive black hole of $3\times
10^{9}M_{\odot}$ at a redshift of $z = 6.41$ in the quasar SDSS
J114816.64+525150.3 could be understood if the black hole completely consumes
the degenerate Fermi ball and then grows by Eddington - limited baryonic
accretion. In the context of this model we constrain the dark matter particle
masses to be within the range from 12 ${\rm keV/c}^{2}$ to about 450 ${\rm
keV/c}^{2}$. Finally we investigate the black hole growth dependence on the
formation time of the seed BH and on the mass of the seed BH. We find that in
order to fit the observed data point of $M_{BH} \sim 3 \times 10^{9}M_{\odot}$
and $z \sim 6.41$, dark matter accretion cannot start later than about $2
\times 10^{8}$ years and the seed BH cannot be greater than about
$10^{4}M_{\odot}$. Our results are in full agreement with the WMAP observations
that indicate that the first onset of star formation might have occurred at a
redshift of $z \sim 15 - 20$. For other models of dark matter particle masses,
corresponding constraints may be derived from the growth of black holes in the
center of galaxies.


title:
D/H in a new Lyman limit quasar absorption system at z=3.256 towards
  PKS1937-1009

abstract:
  We have identified a new Lyman limit absorption system towards PKS1937-1009,
with log N(HI)=18.25 +/- 0.02 at z=3.256. It is suitable for measuring D/H, and
we find a 68.3% confidence range for D/H of 1.6^{+0.25}_{-0.30} \times 10^{-5},
and a 95.4% range of 1.6^{+0.5}_{-0.4} \times 10^{-5}. The metallicity of the
cloud where D/H was measured is low, [Si/H] = -2.0 +/- 0.5. At these
metallicities we expect that D/H will be close to the primordial value. Our D/H
disagrees at a level of 99.4% with the predicted D/H using the baryon density
calculated from the cosmic background radiation measured by WMAP,
2.60^{+0.19}_{-0.17} \times 10^{-5}. Our result also exacerbates the scatter in
D/H values around the mean primordial D/H.


title:
FUSE and STIS Observations of the Warm-Hot Intergalactic Medium towards
  PG1259+593

abstract:
  We use FUSE and STIS spectra to study intergalactic absorption towards the
quasar PG1259+593 (z=0.478). We identify 135 intergalactic absorption lines
with equivalent widths >10mA, tracing 78 absorption components in 72 Ly
alpha/beta absorption-line systems. We concentrate on the distribution and
physical properties of the WHIM as sampled by OVI and intrinsically broad Ly
alpha lines. The number of intervening OVI absorbers for equivalent widths W>24
mA is 3-6 over an unobscured redshift path of dz=0.368. This implies a number
density of OVI systems, dN/dz, of ~8-16 along this sight line. This range is
consistent with estimates from other sight lines, supporting the idea that
intervening intergalactic OVI absorbers contain an substantial fraction of the
baryonic mass in the low-redshift Universe. We identify a number of broad Ly
alpha absorbers with large Doppler parameters (b~40-200 km/s) and low column
densities (N(HI)<10^14 cm^-2). For pure thermal broadening, these widths
correspond to temperatures of ~1x10^5 to 3x10^6 K. While these broad absorbers
could be caused by blends of multiple, unresolved lines, continuum undulations,
or by kinematic flows and Hubble broadening, we consider the possibility that
some of these features are single-component, thermally broadened Ly alpha
lines. These systems could represent WHIM absorbers that are too weak, too
metal-poor, and/or too hot to be detected in OVI. If so, their widths and their
frequency in the PG1259+593 spectrum imply that these absorbers trace an even
larger fraction of the baryons in the low-redshift Universe than the OVI
absorbing systems (abridged version).


title: Molecular hydrogen as baryonic dark matter

abstract:
  High-angular resolution CO observations of small-area molecular structures
(SAMS) are presented. The feature-less structures seen in the single-dish
measurements break up into several smaller clumps in the interferometer map. At
an adopted distance of 100pc their sizes are of order a few hundred AU, some of
which are still unresolved at an angular resolution of about 3". The clumps
have a fractal structure with a fractal index between 1.7 and 2.0. Their
kinetic temperature is between 7K and 18K. Adopting standard conversion factors
masses are about 1/10 Jupiter-masses for individual clumps and densities are
higher than 20000cm^{-3}. The clumps are highly overpressured and it is unknown
what creates or maintains such structures.


title:
Reply to Comment on Strangelets as Cosmic Rays beyond the
  Greisen-Zatsepin-Kuzmin Cutoff

abstract:
  It is argued that strangelets are viable candidates for ultrahigh energy
cosmic rays that circumvent the acceleration and energy-loss problems facing
protons and nuclei, in spite of concerns raised in a comment by Balberg.


title: Particle acceleration in relativistic current sheets

abstract:
  Relativistic current sheets have been proposed as the sites of dissipation in
pulsar winds, jets in active galaxies and other Poynting-flux dominated flows.
It is shown that the steady versions of these structures differ from their
nonrelativistic counterparts because they do not permit transformation to a de
Hoffmann/Teller reference frame, in which the electric field vanishes. Instead,
their generic form is that of a true neutral sheet: one in which the linking
magnetic field component normal to the sheet is absent. Taken together with
Alfven's limit on the total cross-field potential, this suggests plasma is
ejected from the sheet in the cross-field direction rather than along it. The
maximum energy to which such structures can accelerate particles is derived,
and used to compute the maximum frequency of the subsequent synchrotron
radiation. This can be substantially in excess of standard estimates. In the
magnetically driven gamma-ray burst scenario, acceleration of electrons is
possible to energies sufficient to enable photon-photon pair production after
an inverse Compton scattering event.


title: Observations of L1521F: a highly evolved starless core

abstract:
  We observed the pre-stellar core L1521F in dust emission at 1.2mm and in two
transitions each of N2H+, N2D+, C18O, and C17O in order to increase the sample
of well studied centrally concentrated and chemically evolved starless cores,
likely on the verge of star formation, and to determine the initial conditions
for low--mass star formation in the Taurus Molecular Cloud. We derived in this
object a molecular hydrogen number density n(H2) ~ 10^6 cm-3 and a CO depletion
factor, integrated along the line of sight, fD ~ 15 in the central 20'',
similar to the pre-stellar core L1544. However, the N(N2D+)/N(N2H+) column
density ratio is ~0.1, a factor of about 2 lower than that found in L1544. The
observed relation between the deuterium fractionation and the integrated CO
depletion factor across the core can be reproduced by chemical models if N2H+
is slightly (factor of ~2 in fractional abundance) depleted in the central 3000
AU. The N2H+ and N2D+ linewidths in the core center are ~0.3 km/s,
significantly larger than in other more quiescent Taurus starless cores but
similar to those observed in the center of L1544. The kinematical behaviour of
L1521F is more complex than seen in L1544, and a model of contraction due to
ambipolar diffusion is only marginally consistent with the present data. Other
velocity fields, perhaps produced by unresolved substructure, are present. Both
chemical and kinematical analyses suggest that L1521F is less evolved than
L1544, but, in analogy with L1544, it is approaching the ``critical'' state.


title: MeV Gamma-Ray Imaging Detector with micro-TPC

abstract:
  We propose a new imaging gamma-ray detector in the MeV region. By measuring
the directions and energies of not only a scattered gamma ray but also a recoil
electron, the direction of an incident gamma ray would be essentially
reconstructed event by event. Furthermore, one of two measured (zenith and
azimuth) angles of a recoil electron gives us an additional redundancy which
enables us to reject the background events by kinematic constraints. In order
to measure the track of a recoil electron, the micro Time Projection
Chamber($\mu$-TPC) has been developed, which can measure the successive
positions of the track of charged particles in a few hundred micron meter
pitch. The $\mu$-TPC consists of the new type of a gas proportional chamber:
micro PIxel gas Chamber ($\mu$-PIC) which is one of wireless gas chambers and
expected to be robust and stable. Using this $\mu$-TPC and the Anger camera for
the detection of a scattered gamma ray, we have obtained the first gamma-ray
image by the full reconstruction of the direction of gamma rays event by event.


title:
HI in the proto-cluster environment at z>2: absorbing haloes and the
  Lyman alpha forest

abstract:
  We present VLT-UVES echelle spectra of the Lyman alpha emission and
absorption in five radio galaxies at redshifts z=2.55-4.1. Together with data
from our pilot study, we have a sample of 7 such systems with radio source
sizes ~ 1-90 kpc with which to address the origin of the absorbing gas. Echelle
resolution again reveals that some systems with N_HI>1E18 cm^-2 in lower
resolution data in fact consist of several weaker absorbers with N_HI<1E15
cm^-2. We identify two groups of HI absorbers: strong absorbers with
N_HI=1E18-1E20 cm^-2 and weaker systems with N_HI=1E13-1E15 cm^-2. There are
none at intermediate N_HI.
  The strong absorbers may be a by-product of massive galaxy formation or could
instead represent material cooling behind the expanding bow-shock of the radio
jet, as simulated by Krause. New observations are required to discriminate
between these possibilities. We argue that the weaker absorbers with
N_HI=1E13-1E15 cm^-2 are part of the Lyman alpha forest, as their rate of
incidence is within a factor of 2-4 of that in the IGM at large. Such column
densities are consistent with models of a multi-phase proto-intracluster medium
at z>2.


title: Skywalking GEMS and UDF

abstract:
  The two large colour mosaics of the GEMS and UDF projects, both obtained with
the Hubble Space Telescope and ACS, consist of large amounts of data. We
present two web application pages (the GEMS and UDF "Skywalker") that allow to
pan around in these mosaics with downloading only small parts at a time.


title:
An XMM-Newton observation of the massive, relaxed galaxy cluster
  ClJ1226.9+3332 at z=0.89

abstract:
  A detailed X-ray analysis of an XMM-Newton observation of the high-redshift
(z=0.89) galaxy cluster ClJ1226.9+3332 is presented. The X-ray temperature is
found to be 11.5{+1.1}{-0.9}keV, the highest X-ray temperature of any cluster
at z>0.6. In contrast to MS1054-0321, the only other very hot cluster currently
known at z>0.8, ClJ1226.9+3332 features a relaxed X-ray morphology, and its
high overall gas temperature is not caused by one or several hot spots. The
system thus constitutes a unique example of a high redshift, high temperature,
relaxed cluster, for which the usual hydrostatic equilibrium assumption, and
the X-ray mass is most reliable. A temperature profile is constructed (for the
first time at this redshift) and is consistent with the cluster being
isothermal out to 45% of the virial radius. Within the virial radius
(corresponding to a measured overdensity of a factor of 200), a total mass of
(1.4+/-0.5)*10^15 M_solar is derived, with a gas mass fraction of 12+/-5%. The
bolometric X-ray luminosity is (5.3+/-0.2)*10^45 erg/s. The probabilities of
finding a cluster of this mass within the volume of the discovery X-ray survey
are 8*10^{-5} for Omega_M=1 and 0.64 for Omega_M=0.3, making Omega_M=1 highly
unlikely. The entropy profile suggests that entropy evolution is being
observed. The metal abundance (of Z=0.33{+0.14}{-0.10} Z_solar), gas mass
fraction, and gas distribution are consistent with those of local clusters;
thus the bulk of the metals were in place by z=0.89.


title:
Discovery of Blue Luminescence in the Red Rectangle: Possible
  Fluorescence from Neutral Polycyclic Aromatic Hydrocarbon Molecules?

abstract:
  Here we report our discovery of a band of blue luminescence (BL) in the Red
Rectangle (RR) nebula. This enigmatic proto-planetary nebula is also one of the
brightest known sources of extended red emission as well as of unidentified
infra-red (UIR) band emissions. The spectrum of this newly discovered BL is
most likely fluorescence from small neutral polycyclic aromatic hydrocarbon
(PAH) molecules. PAH molecules are thought to be widely present in many
interstellar and circumstellar environments in our galaxy as well as in other
galaxies, and are considered likely carriers of the UIR-band emission. However,
no specific PAH molecule has yet been identified in a source outside the solar
system, as the set of mid-infra-red emission features attributed to these
molecules between the wavelengths of 3.3 micron and 16.4 micron is largely
insensitive to molecular sizes. In contrast, near-UV/blue fluorescence of PAHs
is more specific as to size, structure, and charge state of a PAH molecule. If
the carriers of this near-UV/blue fluorescence are PAHs, they are most likely
neutral PAH molecules consisting of 3-4 aromatic rings such as anthracene
(C14H10) and pyrene (C16H10). These small PAHs would then be the largest
molecules specifically identified in the interstellar medium.


title:
Long Term Spectral and Timing Behavior of the Black Hole Candidate XTE
  J1908+094

abstract:
  We present the long term X-ray light curves, detailed spectral and timing
analyses of XTE J1908+094 using the Rossi X-ray Timing Explorer Proportional
Counter Array observations covering two outbursts in 2002 and early 2003. At
the onset of the first outburst, the source was found in a spectrally low/hard
state lasting for ~40 days, followed by a three day long transition to the
high/soft state. The source flux (in 2$-$10 keV) reached $\sim$100 mCrab on
2002 April 6, then decayed rapidly. In power spectra, we detect strong
band-limited noise and varying low-frequency quasi periodic oscillations that
evolved from ~0.5 Hz to ~5 Hz during the initial low/hard state of the source.
We find that the second outburst closely resembled the spectral evolution of
the first. The X-ray transient's overall outburst characteristics lead us to
classify XTE J1908+094 as a black-hole candidate. Here we also derive precise
X-ray position of the source using Chandra observations which were performed
during the decay phase of the first outburst and following the second outburst.


title: Mapping the Outflow from G5.89-0.39 in SiO(5-4)

abstract:
  We have mapped the ultracompact HII region, G5.89-0.39, and its molecular
surroundings with the Submillimeter Array at 2".8 x 1".8 angular resolution in
1.3 mm continuum, SiO(5-4), and eight other molecular lines. We have resolved
for the first time the highly energetic molecular outflow in this region. At
this resolution, the outflow is definitely bipolar and appears to originate in
a 1.3 mm continuum source. The continuum source peaks in the center of the HII
region. The axis of the outflow lines up with a recently discovered O5V star.


title:
The Stellar Populations in the Outer Regions of M33. I. Metallicity
  Distribution Function

abstract:
  We present deep CCD photometry in the VI passbands using the WIYN 3.5m
telescope of a field located approximately 20' southeast of the center of M33;
this field includes the region studied by Mould & Kristian in their 1986 paper.
The color-magnitude diagram (CMD) extends to I~25 and shows a prominent red
giant branch (RGB), along with significant numbers of asymptotic giant branch
and young main sequence stars. The red clump of core helium burning stars is
also discernable near the limit of our CMD. The I-band apparent magnitude of
the red giant branch tip implies a distance modulus of (m-M)_I = 24.77 +/-
0.06, which combined with an adopted reddening of E(V-I)=0.06 +/- 0.02 yields
an absolute modulus of (m-M)_0 = 24.69 +/- 0.07 (867 +/- 28 kpc) for M33. Over
the range of deprojected radii covered by our field (~8.5 to ~12.5 kpc), we
find a significant age gradient with an upper limit of ~1 Gyr (~0.25 Gyr/kpc).
Comparison of the RGB photometry to empirical giant branch sequences for
Galactic globulars allows us to use the dereddened color of these stars to
construct a metallicity distribution function (MDF). The primary peak in the
MDF is at a metallicity of [Fe/H] ~ -1.0 with a tail to lower abundances. The
peak does show radial variation with a slope of d[Fe/H]/dR_{deproj} = -0.06 +/-
0.01 dex/kpc. This gradient is consistent with the variation seen in the inner
disk regions of M33. As such, we conclude that the vast majority of stars in
this field belong to the disk of M33, not the halo as previously thought.


title: Tracking Quintessence Would Require Two Cosmic Coincidences

abstract:
  Good tracking requires that the quintessence energy fraction slowly increase
while the roll $\lambda\equiv -d\ln V/\varkappa d\phi$ slowly decreases, but is
not yet truly slow-rolling. The supernova bound on the present quintessence
equation of state requires either (1) a cosmological constant or other
fine-tuned "crawling quintessence" or (2) "roll-over quintessence" that tracked
until recently, but now became slow rolling, because of a sharp increase in
potential curvature. Thus, fine-tuning is required by constant equation of
state and inverse power potentials, but can be avoided by the SUGRA and
Skordis-Albrecht potentials and other good trackers, provided quintessence
energy domination and slow roll {\em both} began only recently. This makes the
time in which we live special in {\em two} respects.


title:
Reply to ``Cuts and penalties: comment on `The clustering of ultra-high
  energy cosmic rays and their sources' ''

abstract:
  We reiterate that there is no evidence that BL Lacs are sources of ultrahigh
energy cosmic rays.


title:
Diffuse inverse Compton and synchrotron emission from dark matter
  annihilations in galactic satellites

abstract:
  Annihilating dark matter particles produce roughly as much power in electrons
and positrons as in gamma ray photons. The charged particles lose essentially
all of their energy to inverse Compton and synchrotron processes in the
galactic environment. We discuss the diffuse signature of dark matter
annihilations in satellites of the Milky Way (which may be optically dark with
few or no stars), providing a tail of emission trailing the satellite in its
orbit. Inverse Compton processes provide X-rays and gamma rays, and synchrotron
emission at radio wavelengths might be seen. We discuss the possibility of
detecting these signals with current and future observations, in particular
EGRET and GLAST for the gamma rays.


title:
Strongest gravitational waves from neutrino oscillations at supernova
  core bounce

abstract:
  Resonant active-to-active ($\nu_a \to \nu_a$), as well as active-to-sterile
($\nu_a \to \nu_s$) neutrino ($\nu$) oscillations can take place during the
core bounce of a supernova collapse. Besides, over this phase, weak magnetism
increases antineutrino ($\bar{\nu}$) mean free paths, and thus its luminosity.
Because the oscillation feeds mass-energy into the target $\nu$ species, the
large mass-squared difference between species ($\nu_a \to \nu_s$) implies a
huge amount of energy to be given off as gravitational waves ($L_{\textrm{GWs}}
\sim 10^{49}$ erg s$^{-1}$), due to anisotropic but coherent $\nu$ flow over
the oscillation length. This asymmetric $\nu$-flux is driven by both the
spin-magnetic and the {\it universal spin-rotation} coupling. The novel
contribution of this paper stems from 1) the new computation of the anisotropy
parameter $\alpha \sim 0.1-0.01$, and 2) the use of the tight constraints from
neutrino experiments as SNO and KamLAND, and the cosmic probe WMAP, to compute
the gravitational-wave emission during neutrino oscillations in supernovae core
collapse and bounce. We show that the mass of the sterile neutrino $\nu_s$ that
can be resonantly produced during the flavor conversions makes it a good
candidate for dark matter as suggested by Fuller et {\it al.} (2003). The new
spacetime strain thus estimated is still several orders of magnitude larger
than those from $\nu$ difussion (convection and cooling) or quadrupole moments
of neutron star matter. This new feature turns these bursts the more promissing
supernova gravitational-wave signal that may be detected by observatories as
LIGO, VIRGO, etc., for distances far out to the VIRGO cluster of galaxies.


title:
Radio Emission as a Test of the Existence of Intermediate Mass Black
  Holes in Globular Clusters and Dwarf Spheroidal Galaxies

abstract:
  We take the established relation between black hole mass, X-ray luminosity,
and radio luminosity and show that intermediate mass black holes, such as those
predicted to exist at the centers of globular clusters, will be easily
identifiable objects in deep radio observations. We show that the radio
observations will be far more senstive than any possible X-ray observations. We
also discuss the likely optical photometric and spectroscopic appearance of
such systems in the event that radio detections are made.


title:
What drives the Balmer extinction sequence in spiral galaxies? Clues
  from the Sloan Digital Sky Survey

abstract:
  Using spectra of normal emission line galaxies from the First Data Release of
the Sloan Digital Sky Survey (SDSS) we have investigated the relations between
the extinction $C({\rm H}\beta)$ as derived from the \Ha/\Hb emission line
ratio and various global parameters of the galaxies. Our main findings are
that: 1) $C({\rm H}\beta)$ is linked with the galaxy spectral type and colour,
decreasing from early- to late-type spirals. 2) $C({\rm H}\beta)$ increases
with increasing metallicity. 3) $C({\rm H}\beta)$ is larger in galaxies with an
older stellar population. 4) $C({\rm H}\beta)$ is larger for more luminous
galaxies. 5) The extinction of the stellar light is correlated with both the
extinction of the nebular light and the intrinsic galaxy colours. We propose
phenomenological interpretations of our empirical results. We have also
cross-correlated our sample of SDSS galaxies with the IRAS data base. Due to
the lower redshift limit imposed to our sample and to the detection limit of
IRAS, such a procedure selected only luminous infrared galaxies. We found that
correlations that were shown by other authors to occur between optical and
infrared properties of galaxies disappear when restricting the sample to
luminous infrared galaxies. We also found that the optical properties of the
luminous infrared galaxies in our SDSS sample are very similar to those of our
entire sample of SDSS galaxies. This may be explained by the IRAS luminosity of
the galaxies originating in the regions that formed massive stars less than 1
Myr ago, while the opacity of galaxies as derived from the \Ha/\Hb emission
line ratio is due to diffuse dust.
  We show some implications of our empirical results on the determination of
global star formation rates and total stellar masses in normal galaxies.


title: Broadband X-ray spectrum of intermediate polar V1223 Sgr

abstract:
  We present the broadband phase averaged spectrum of one of the brightest
intermediate polars V1223 Sgr, obtained with INTEGRAL and RXTE observatories
(3-100 keV). Good statistical quality of the spectrum in a hard X-ray energy
band (INTEGRAL/IBIS and RXTE/HEXTE) allowed us to disentangle contributions of
a direct optically thin plasma emission and a reflected component to the
spectrum of V1223 Sgr. The obtained measurement of the post-shock temperature
of the accreting matter give us the information about the mass of the white
dwarf and the inclination of the system.


title:
Binary corrected X-ray light curve of Cygnus X-3 : implications for the
  timing properties of the compact binary system

abstract:
  We study the binary corrected X-ray light curve of Cygnus X-3 using the
RXTE-ASM data and RXTE-PCA data. We find that the X-ray template derived from
the EXOSAT observations adequately explains the binary variations. Using the
recently determined quadratic binary ephemeris we correct the RXTE-PCA
lightcurve and obtain the power spectrum which shows distinct features of
shifting towards the low frequency regime vis-a-vis the Galactic X-ray
binaries. The power spectrum doesn't vary from the hard to the soft state. We
also obtain the binary corrected RXTE-ASM monitoring lightcurve and examine the
previously obtained correlation between soft X-ray (2-12 keV from RXTE-ASM),
hard X-ray (20-100 keV from CGRO-BATSE) and radio (2.2 GHz from GBI) after the
binary correction. We find that the correlation time scale is less than a day.


title: Can the Stephani model be an alternative to FRW accelerating models?

abstract:
  A class of Stephani cosmological models as a prototype of non-homogeneous
universe is considered. The non-homogeneity can lead to accelerated evolution
which is now observed from the SNIa data. Three samples of type Ia supernovae
obtained by Perlmutter at al., Tonry et al. and Knop et al. are taken into
account. Different statistical methods (best fits as well as maximum likelihood
method) to obtain estimates of the model parameters are used. Stephani model is
considered as an alternative to the concordance of Lambda-CDM model in the
explanation of the present acceleration of the universe. The model explains the
acceleration of the universe at the same level of accuracy as the Lambda-CDM
model. From the best fit analysis it follows that the Stephani model is
characterized by higher value of nonrelativistic matter density parameter than
the Lambda-CDM model. It is also shown that the obtained results are consistent
with location of CMB peaks.


title:
The evolution of the luminosity functions in the FORS Deep Field from
  low to high redshift: I. The blue bands

abstract:
  We use the very deep and homogeneous I-band selected dataset of the FORS Deep
Field (FDF) to trace the evolution of the luminosity function over the redshift
range 0.5 < z < 5.0. We show that the FDF I-band selection down to I(AB)=26.8
misses of the order of 10 % of the galaxies that would be detected in a K-band
selected survey with magnitude limit K(AB)=26.3 (like FIRES). Photometric
redshifts for 5558 galaxies are estimated based on the photometry in 9 filters
(U, B, Gunn g, R, I, SDSS z, J, K and a special filter centered at 834 nm). A
comparison with 362 spectroscopic redshifts shows that the achieved accuracy of
the photometric redshifts is (Delta z / (z_spec+1)) < 0.03 with only ~ 1 %
outliers. This allows us to derive luminosity functions with a reliability
similar to spectroscopic surveys. In addition, the luminosity functions can be
traced to objects of lower luminosity which generally are not accessible to
spectroscopy. We investigate the evolution of the luminosity functions
evaluated in the restframe UV (1500 Angstroem and 2800 Angstroem), u', B, and
g' bands. Comparison with results from the literature shows the reliability of
the derived luminosity functions. Out to redshifts of z ~ 2.5 the data are
consistent with a slope of the luminosity function approximately constant with
redshift, at a value of -1.07 +- 0.04 in the UV (1500 Angstroem, 2800
Angstroem) as well as u', and -1.25 +- 0.03 in the blue (g', B). We do not see
evidence for a very steep slope (alpha < -1.6) in the UV at z ~ 3.0 and z ~ 4.0
favoured by other authors. There may be a tendency for the faint-end slope to
become shallower with increasing redshift but the effect is marginal. We find a
brightening of M_star and a decrease of Phi_star with redshift for all analyzed
wavelengths. [abridged]


title: The star formation history of intermediate redshift late-type galaxies

abstract:
  We combine the latest observations of disk galaxy photometry and rotation
curves at moderate redshift from the FORS Deep Field (FDF) with simple models
of chemical enrichment. Our method describes the buildup of the stellar
component through infall of gas and allows for gas and metal outflows. In this
framework, we keep a minimum number of constraints and we search a large volume
of parameter space, looking for the models which best reproduce the photometric
observations in the observed redshift range (0.5<z<1). We find the star
formation efficiency to correlate well with vMAX so that massive disks are more
efficient in the formation of stars and have a smaller spread in stellar ages.
This trend presents a break at around vMAX 140km/s. Galaxies on either side of
this threshold have significantly different age distributions. This break has
been already suggested by several authors in connection with the contribution
from either gravitational instabilities or supernova-driven turbulence to star
formation. No clear trend is seen between galaxy mass and infall timescale or
gas outflows. The model presented in this paper suggests massive disks have
formation histories resembling those of early-type galaxies, with highly
efficient and short-lived bursts, in contrast with low-mass disks, which have a
more extended star formation history. One option to explain the observed
shallow slope of the Tully-Fisher relation at intermediate redshift could be
small episodes of star formation in low-mass disks.


title: Detection of D2H+ in the Dense Interstellar Medium

abstract:
  The 692 GHz para ground-state line of D2H+ has been detected at the Caltech
Submillimeter Observatory towards the pre-stellar core 16293E. The derived D2H+
abundance is comparable to that of H2D+, as determined by observations of the
372 GHz line of ortho-H2D+. This is an observational verification of recent
theoretical predictions (Roberts, Herbst & Millar 2003), developed to explain
the large deuteration ratios observed in cold, high-density regions of the
interstellar medium associated with low mass pre-stellar cores and protostars.
This detection confirms expectations that the multiply deuterated forms of H3+
were missing factors of earlier models. The inclusion of D2H+ and D3+ in the
models leads to predictions of higher values of the D/H ratio in the gas phase.


title:
Resolving the Host Galaxy of the Nearby QSO I Zw 1 with Sub-Arcsecond
  Multi-Transition Molecular Line Observations

abstract:
  We present the first sub-kpc 0.7" (~ 850 pc) resolution 12CO(1-0) molecular
line observations of the ISM in the host galaxy of the QSO I Zw 1. The
observations were obtained with the BIMA mm-interferometer in its compact A
configuration. The BIMA data are complemented by new observations of the
12CO(2-1) and 13CO(1-0) line with IRAM Plateau de Bure mm-interferometer (PdBI)
at 0.9" and 1.9" resolution, respectively. These measurements, which are part
of a multi-wavelength study of the host galaxy of I Zw 1, are aimed at
comparing the ISM properties of a QSO host with those of nearby galaxies as
well as to obtain constraints on galaxy formation/evolution models. Our images
of the 12CO(1-0) line emission show a ring-like structure in the circumnuclear
molecular gas distribution with an inner radius of about 1.2 kpc. The presence
of such a molecular gas ring was predicted from earlier lower angular
resolution PdBI 12CO(1-0) observations. A comparison of the BIMA data with IRAM
PdBI 12CO(2-1) observations shows variations in the excitation conditions of
the molecular gas in the innermost 1.5" comprising the nuclear region of I Zw
1. The observed properties of the molecular cloud complexes in the disk of the
host galaxy suggest that they can be the sites of massive circumnuclear star
formation, and show no indications of excitation by the nuclear AGN. This all
indicates that the molecular gas in a QSO host galaxy has similar properties to
the gas observed in nearby low luminosity AGNs.


title: Hard X-ray Timing with EXIST

abstract:
  The Energetic X-ray Timing Survey Telescope (EXIST) mission concept is under
study as the Black Hole Finder Probe (BHFP), one of the three Einstein Probe
missions in the Beyond Einstein Program in the current NASA Strategic Plan.
EXIST would conduct an all-sky imaging hard X-ray ($\sim$10-600 keV) survey
with unprecedented sensitivity: about 5 $\times 10^{-13}$ cgs over any factor
of 2 bandwidth, or comparable to that achieved at soft X-rays in the ROSAT
survey. The proposed angular resolution of 5arcmin, temporal resolution of
10microsec, energy resolution of 1-4 keV over the broad band, and duty cycle of
0.2-0.5 for continuous coverage of any source provide an unprecedented phase
space for timing and spectral studies of black holes --from stellar to
supermassive, as well as neutron stars and accreting white dwarfs. The large
sky coverage allows intrinsically rare events to be studied. One particularly
exciting example is the possible detection of tidal disruption of stars near
quiescent AGN. Super flares from SGRs could be detected out to the Virgo
cluster. The large duty cycle and all sky monitor nature of the mission will
enable QPOs from luminous AGN and BH X-ray binaries to be studied on timescales
not possible before. I provide an overview of the mission concept and Reference
Design, the X-ray timing science prospects for EXIST, and how these might be
further optimized in the current Study for EXIST as the BHFP so that EXIST
might include many of the desirable features of a next-generation timing
mission.


title:
Photo-Luminescence and Possible Forsterite nanoparticles Model of
  Extended Red Emission

abstract:
  Possible forsterite nanoparticle model of the Extended Red Emission(ERE) is
proposed on the basis of photo-luminescence of forsterite after gamma-ray and
neutron irradiation. Forsterite exhibits interesting thermoluminescence
spectrum similar to ERE of Red Rectangle after irradiation in low temperature.
It is shown that the forsterite after thermoluminescence is over exhibits
photo-luminescence(PL) when Ultraviolet ray is irradiated. The structure of PL
spectrum is almost similar to that of thermoluminescence. In order to explain
small variations of the peak position of wavelength of ERE spectrum, possible
nanoparticle model of forsterite is investigated. Our model is consistent to
the ISO observation data in near and middle infrared region, which suggest the
existence of forsterite.


title:
An extended scheme for fitting X-ray data with accretion disk spectra in
  the strong gravity regime

abstract:
  Accreting black holes are believed to emit X-rays which then mediate
information about strong gravity in the vicinity of the emission region. We
report on a set of new routines for the Xspec package for analysing X-ray
spectra of black-hole accretion disks. The new computational tool significantly
extends the capabilities of the currently available fitting procedures that
include the effects of strong gravity, and allows one to systematically explore
the constraints on more model parameters than previously possible (for example
black-hole angular momentum). Moreover, axial symmetry of the disk intrinsic
emissivity is not assumed, although it can be imposed to speed up the
computations. The new routines can be used also as a stand-alone and flexible
code with the capability of handling time-resolved spectra in the regime of
strong gravity. We have used the new code to analyse the mean X-ray spectrum
from the long XMM--Newton 2001 campaign of the Seyfert 1 galaxy MCG--6-30-15.
Consistent with previous findings, we obtained a good fit to the broad Fe K
line profile for a radial line intrinsic emissivity law in the disk which is
not a simple power law, and for near maximal value of black hole angular
momentum. However, equally good fits can be obtained also for small values of
the black hole angular momentum. The code has been developed with the aim of
allowing precise modelling of relativistic effects. Although we find that
current data cannot constrain the parameters of black-hole/accretion disk
system well, the approach allows, for a given source or situation, detailed
investigations of what features of the data future studies should be focused on
in order to achieve the goal of uniquely isolating the parameters of such
systems.


title:
SZ scaling relations in Galaxy Clusters: results from hydrodynamical
  N-body simulations

abstract:
  Observations with the SZ effect constitute a powerful new tool for
investigating clusters and constraining cosmological parameters. Of particular
interest is to investigate how the SZ signal correlates with other cluster
properties, such as the mass, temperature and X-ray luminosities. In this
presentation we quantify these relations for clusters found in hydrodynamical
simulations of large scale structure and investigate their dependence on the
effects of radiative cooling and pre-heating.


title: Dark halo baryons not in ancient halo white dwarfs

abstract:
  Having ruled out the possibility that stellar objects are the main
contributor of the dark matter embedding galaxies, microlensing experiments
cannot exclude the hypothesis that a significant fraction of the Milky Way dark
halo might be made of MACHOs with masses in the range $0.5-0.8 \msun$. Ancient
white dwarfs are generally considered the most plausible candidates for such
MACHOs. We report the results of a search for such white dwarfs in a proper
motion survey covering a 0.16 sqd field at three epochs at high galactic
latitude, and 0.938 sqd at two epochs at intermediate galactic latitude (VIRMOS
survey), using the CFH telescope. Both surveys are complete to I = 23, with
detection efficiency fading to 0 at I = 24.2. Proper motion data are suitable
to separate unambiguously halo white dwarfs identified by belonging to a non
rotating system. No candidates were found within the colour-magnitude-proper
motion volume where such objects can be safely discriminated from any standard
population as well as from possible artefacts. In the same volume, we estimate
the maximum white dwarf halo fraction compatible with this observation at
different significance levels if the halo is at least 14 gigayears old and
under different ad hoc initial mass functions. Our data alone rules out a halo
fraction greater than 14% at 95% confidence level. Combined with two previous
investigations exploring comparable volumes pushes the limit below 4 % (95%
confidence level) or below 1.3% (64% confidence), this implies that if baryonic
dark matter is present in galaxy halos, it is not, or it is only marginally in
the form of faint hydrogen white dwarfs.


title:
The clustering of galaxies around three damped Ly-alpha absorbers at
  Redshift Three

abstract:
  [Abridged] We present out results on the cross-correlation of Lyman break
galaxies (LBGs) around three damped \Ly absorbers (DLAs) at redshift three from
deep multi-band MOSAIC images obtained at the KPNO 4m. The large area of the
MOSAIC images, 0.31 $\deg^2$ allows us to probe the clustering of LBGs on
scales up to 20 Mpc co-moving to test whether DLA halos are more or less
massive than LBG halos. . We present our survey that covers a total of 1
deg$^2$ and contains $\sim$3,000 LBGs with photometric redshifts between 2.8
and 3.5.
  Within a redshift slice of width $W_z=0.15$, we find that the DLA-LBG
cross-correlation is $1.6\pm 1.3$ times the LBG-LBG autocorrelation. This
corresponds to a correlation length of $r_o=5\pm4.5h^{-1}$ (co-moving). The
cross-correlation is most significant on scales 5-10 Mpc, and is significantly
greater than zero at the $>95$% level from Monte Carlo simulations.


title: The LEDA galaxy distribution: I. Maps of the Local Universe

abstract:
  In order to investigate the properties of large-scale structures of galaxies
in the universe, we present an analysis of their spatial distribution at
z$<$0.033. We used the LEDA extragalactic database containing over 1 million of
galaxies covering the all-sky and the SDSS data included in the public release
DR1, yielding to a sample of around 134,000 galaxies having a measured redshift
in two survey areas representing 690 sq. degrees. The results of the study are
2D, 3D maps and magnitude number counts of galaxies, drawn from B-band samples.
  Movies and high resolution figures are available on
http://www-obs.univ-lyon1.fr/cosmologie/helene.html


title: Spectral transitions in X-ray Binaries

abstract:
  We systematically analyzed about a terabyte of data from Galactic binary
systems to characterize how these spectra change as a function of mass
accretion rate. With this volume of data we are able to identify the
differences in behaviour of black holes and neutron stars, implying that black
holes really do have an event horizon. The spectral evolution seen as a
function of L/L_Edd can be linked to current state-of-the-art numerical
simulations of accretion flows, and we develop qualitative and quantitative
models of the spectral changes in all types of binary systems. The key
ingredient of this picture is that the major hard-soft spectral transition is
driven by a changing inner radius of the accretion disc. This also
qualitatively explains the changes seen in the variability power spectra of
these objects. This lays the foundation for a self-consistent, theoretically
motivated framework in which to explain both the spectral and timing properties
of accreting compact objects.


title: The structure of radiative shock waves. V. Hydrogen emission lines

abstract:
  We considered the structure of steady-state plane-parallel radiative shock
waves propagating through the partially ionized hydrogen gas of temperature T_1
= 3000K and density 1e-12 gm/cm^3 <= \rho_1 <= 1e-9 gm/cm^3. The upstream Mach
numbers range within 6 <= M_1 <= 14. In frequency intervals of hydrogen lines
the radiation field was treated using the transfer equation in the frame of the
observer for the moving medium, whereas the continuum radiation was calculated
for the static medium. Doppler shifts in Balmer emission lines of the radiation
flux emerging from the upstream boundary of the shock wave model were found to
be roughly one-third of the shock wave velocity. The gas emitting the Balmer
line radiation is located at the rear of the shock wave in the hydrogen
recombination zone where the gas flow velocity in the frame of the observer is
approximately one-half of the shock wave velocity. The ratio of the Doppler
shift to the gas flow velocity of 0.7 results both from the small optical
thickness of the shock wave in line frequencies and the anisotropy of the
radiation field typical for the slab geometry. In the ambient gas with density
of \rho_1 >= 1e-11 gm/cm^3 the flux in the H-alpha frequency interval reveals
the double structure of the profile. A weaker H-beta profile doubling was found
for \rho_1 >= 1e-10 gm/cm^3 and U_1 <= 50 km/s. The unshifted redward component
of the double profile is due to photodeexcitation accompanying the rapid growth
of collisional ionization in the narrow layer in front of the discontinuous
jump.


title: 2-100 keV Spectrum of an Actively Star Forming Galaxy

abstract:
  We compute the synthetic 2-100 keV spectrum of an actively star forming
galaxy. To this aim we use a luminosity function of point sources appropriate
for starbursts (based on Chandra data), as well as the types of stellar sources
and their corresponding spectra. Our estimates indicate that a Compton spectral
component - resulting from scattering of SN-accelerated electrons by ambient
FIR and CMB photons - could possibly be detected, in deep INTEGRAL observations
of nearby starburst galaxies, only if there is a break in the spectra of the
brightest (L > 2x10^{38} erg/s) point sources.


title: Optical Bumps in Cosmological GRBs as Supernovae

abstract:
  From both photometric and broadband spectral monitoring of gamma-ray burst
(GRB) lightcurve ``bumps,'' particularly in GRB 011121, a strong case grew for
a supernova (SN) origin. The GRB-SN connection was finally solidified beyond a
reasonable doubt with the discovery that the bump in GRB 030329 was
spectroscopically similar to a bright Type Ic SN. In light of this result, I
redress the previous SN bump claims and conclude that 1) the distribution of
GRB-SN bump peak magnitudes is consistent with the local Type Ibc SNe peak
distribution and suggest that 2) the late-time bumps in all long-duration GRBs
are likely supernovae.


title: Surface gravity of neutron stars and strange stars

abstract:
  The upper bound on the value of the surface gravity, g_s, for neutron stars
with equations of state respecting v_sound <= c, is derived. This bound is
inversely proportional to the maximum allowable mass M_max, and it reads g_s <=
1.411 x 10^15 (M_sun/M_max) cm/s^2. It implies an absolute upper bound 7.4 x
10^14 cm/s^2 if one uses the 2sigma lower bound on the neutron mass measured
recently in 4U1700-37, 1.9 M_sun. A correlation between g_s and the compactness
parameter 2GM/Rc^2 for baryonic stars is analyzed. The properties of g_s of
strange quark stars and its upper bounds are discussed using the scaling
properties of the strange-star models.