title: Spectroscopy of the Optical Counterpart to Ser X-1

abstract:
  We present WHT and VLT spectroscopy of MM Ser, the optical counterpart to Ser
X-1. We deblend the red spectra of the two close stars identified by Wachter
(1997) and show that the brighter of the two is responsible for the Halpha and
HeI emission, hence confirming that this is the true counterpart of the X-ray
source. We also identify several HeII and NIII lines in the blue spectrum. The
isolated emission lines are all remarkably narrow, with FWHM 200-300 km/s. The
Bowen blend has structure suggesting that the individual components are also
narrow. These narrow lines could be from the disc if the binary inclination is
quite low, or they could come from a more localised region such as the heated
face of the companion star. Several interstellar lines are detected and
indicate that the reddening is moderate, and consistent with the neutral
hydrogen column density inferred in X-rays.


title: NUclei of GAlaxies (NUGA): the IRAM Survey of Low Luminosity AGN

abstract:
  The NUGA project is the first high-resolution (0.5''-1'') CO survey of low
luminosity AGN including the full sequence of activity types (Seyfert 1--2 and
LINERs). NUGA aims to study systematically the different mechanisms for gas
fueling of the AGN. In order to reach the critical spatial scales for AGN
feeding (<100 pc), we are undertaking high-resolution observations, made at the
Plateau de Bure Interferometer, to achieve a sharp view of the distribution and
kinematics of molecular gas. In this talk we discuss the latest results of this
survey which now includes newly acquired subarcsec resolution observations for
5 targets of our sample. The large variety of circumnuclear disk morphologies
found in NUGA galaxies (m=1, m=2 and m=0-type gravitational instabilities) is a
challenging result that urges the refinement of current dynamical models.


title:
Is there a dichotomy in the Dark Matter as well as in the Baryonic
  Matter properties of ellipticals?

abstract:
  We have found a correlation betwen the M/L global gradients and the
structural parameters of the luminous components of a sample of 19 early-type
galaxies. Such a correlation supports the hypothesis that there is a connection
between the dark matter content and the evolution of the baryonic component in
such systems.


title: High Velocity Gas in the Halos of Spiral Galaxies

abstract:
  Recent, high sensitivity, HI observations of nearby spiral galaxies show that
their thin `cold' disks are surrounded by thick layers (halos) of neutral gas
with anomalous kinematics. We present results for three galaxies viewed at
different inclination angles: NGC891 (edge-on), NGC2403 (i=60 deg), and NGC6946
(almost face-on). These studies show the presence of halo gas up to distances
of 10-15 kpc from the plane. Such gas has a mean rotation 25-50 km/s lower than
that of the gas in the plane, and some complexes are detected at very high
velocities, up to 200-300 km/s. The nature and origin of this halo gas are
poorly understood. It can either be the result of a galactic fountain or of
accretion from the intergalactic medium. It is probably the analogous of some
of the High Velocity Clouds (HVCs) of the Milky Way.


title: Galactic Binaries as Sources of Gravitational Waves

abstract:
  I review the expected Galactic sources of gravitational waves, concentrating
on the low-frequency domain and summarise the current observational and
theoretical knowledge we have. A model for the Galactic population of close
binaries, which is tested against the observations is used to predict the
expected signal for the future space based gravitational wave detector LISA.
With a simple model for the electro-magnetic emission from the same binaries I
argue that a fair number of the LISA systems have electro-magnetic
counterparts, which can be used to improve in particular the distance and mass
measurements of these systems by LISA. Furthermore, LISA will enable us to test
some aspects of the theory of binary evolution that are very difficult to asses
in different ways.


title: Lighting up the dark and dim in the Andromeda Galaxy

abstract:
  I discuss current and future applications of pixel lensing: the microlensing
of unresolved stars. Pixel lensing is the tool of choice for studying the Macho
dark matter content of external galaxies like Andromeda (M31), and is at the
heart of an ambitious new proposal to undertake a census of low-mass stars and
brown dwarfs in the M31 bulge.


title:
Spatial Distributions of A3558 in the Core Region of the Shapley
  Supercluster

abstract:
  The core region is dominated by three rich Abell clusters and two poor
clusters. Their spatial distributions of gas temperature and metal abundance
provide us with information on the interactions and motions of member clusters.
  From eight ASCA pointing observations, temperature, abundance, and X-ray
luminosity for five member clusters are similar to the other field clusters not
belonging to superclusters. This result and the mean gravitational mass density
of the core region indicate that the members are growing in the same way as the
nonmember clusters, and the core of the supercluster is just on the way to
contraction. Based on analyses of detailed spatial structures with a 4'x4'
scale, the three Abell clusters show asymmetric temperature distributions.
A3558 was analyzed with a 2'x2' scale, owing to the statistical advantage, and
it was revealed that A3558 has clear asymmetric distributions of gas
temperature and X-ray surface brightness. This is thought to be caused by
cluster-cluster mergings and/or group infallings. A metal-rich region with the
size of ~320 kpc was also found to the southeast, ~12' away from the cluster
center of A3558. It is expected that either a remnant of a merged core has been
left after a major merging or a group of galaxies has been recently infalling.


title: Magellanic Cloud PNs as probes of stellar evolution and populations

abstract:
  Magellanic Cloud Planetary Nebulae (PNs) offer insight of both the population
and evolution of low- and intermediate-mass stars, in environments that are
free of the distance bias and the differential reddening that hinder the
observations of the Galactic sample. The study of LMC and SMC PNs also offers
the direct comparison of stellar populations with different metallicity. We
present a selection of the results from our recent HST surveys, including (1)
the morphological analysis of Magellanic PNs, and the statistics of the
morphological samples in the LMC and the SMC; (2) the surface brightness versus
radius relationship; and (3) the analysis and modeling of the [O III]/H(beta)
PN luminosity functions in the LMC and the SMC.


title: The X-ray Background and AGNs

abstract:
  Deep X-ray surveys have shown that the cosmic X-ray background (XRB) is
largely due to the accretion onto supermassive black holes, integrated over the
cosmic time. These surveys have resolved more than 80% of the 0.1-10 keV X-ray
background into discrete sources. Optical spectroscopic identifications show
that the sources producing the bulk of the X-ray background are a mixture of
unobscured (type-1) and obscured (type-2) AGNs, as predicted by the XRB
population synthesis models. A class of highly luminous type-2 AGN, so called
QSO-2s, has been detected in the deepest Chandra and XMM-Newton surveys. The
new Chandra AGN redshift distribution peaks at much lower redshifts (z~0.7)
than that based on ROSAT data, and the new X-ray luminosity function indicates
that the space density of Seyfert galaxies peaks at significantly lower
redshifts than that of QSOs. It is shown here, that the low redshift peak
applies both to absorbed and unabsorbed AGN and is also seen in the 0.5-2 keV
band alone. Previous findings of a strong dependence of the fraction of type-2
AGN on luminosity are confirmed with better statistics here. Preliminary
results from an 800 ksec XMM-Newton observation of the Lockman Hole are
discussed.


title: The Mid-Infrared Spectra of Brown Dwarfs

abstract:
  We present an analysis of brown dwarf model spectra in the mid-infrared
spectral region (5 - 20 microns), in anticipation of data obtained with the
Space Infrared Telescope Facility. The mid-infrared spectra of brown dwarfs are
in several ways simpler than those in the near-infrared and yet provide
powerful diagnostics of brown dwarf atmospheric physics and chemistry,
especially when combined with ground-based data. We discuss the possibility of
detection of new molecular species and of the silicate cloud, predict strong
observational diagnostics for non-equilibrium chemistry between CO and CH4, and
N2 and NH3, and speculate on the possibility of discovering brown dwarf
stratospheres.


title:
Double-Barred Galaxies: I. A Catalog of Barred Galaxies with Stellar
  Secondary Bars and Inner Disks

abstract:
  I present a catalog of 67 barred galaxies which contain distinct, elliptical
stellar structures inside their bars. Fifty of these are double-barred
galaxies: a small-scale, "inner" or "secondary" bar is embedded within a
large-scale, "outer" or "primary" bar. I provide homogenized measurements of
the sizes, ellipticities, and orientations of both inner and outer bars, along
with with global parameters for the galaxies. The other 17 are classified as
"inner-disk" galaxies, where a large-scale bar harbors an inner elliptical
structure which is aligned with the galaxy's outer disk. Four of the
double-barred galaxies also possess inner disks, located in between the inner
and outer bars. While the inner-disk classification is ad-hoc -- and
undoubtedly includes some inner bars with chance alignments (five such probable
cases are identified) -- there is good evidence that inner disks form a
statistically distinct population, and that at least some are indeed disks
rather than bars. In addition, I list 36 galaxies which may be double-barred,
but for which current observations are ambiguous or incomplete, and another 23
galaxies which have been previously suggested as potentially being
double-barred, but which are probably *not*. False double-bar identifications
are usually due to features such as nuclear rings and spirals being
misclassified as bars; I provide some illustrated examples of how this can
happen.


title:
Magellanic Cloud planetary nebulae as probes of stellar evolution and
  populations

abstract:
  Planetary Nebulae (PNs) in the Magellanic Clouds offer the unique opportunity
to study both the population and evolution of low- and intermediate-mass stars,
in an environment that is free of the distance scale bias and the differential
reddening that hinder the observations of the Galactic sample. The study of LMC
and SMC PNs also offers the direct comparison of stellar populations with
different metallicity. The relative proximity of the Magellanic Clouds allows
detailed spectroscopic analysis of the PNs therein, while the Hubble Space
Telescope (HST) is necessary to obtain their spatially-resolved images. In this
paper we discuss the history and evolution of this relatively recent branch of
stellar astrophysics by reviewing the pioneering studies, and the most recent
ground- and space-based achievements. In particular, we present the results
from our recent HST surveys, including the metallicity dependence of PN
identification (and, ultimately, the metallicity dependence of PN counts in
galaxies); the morphological analysis of Magellanic PNs, and the correlations
between morphology and other nebular properties; the relations between
morphology and progenitor mass and age; and the direct analysis of Magellanic
central stars and their importance to stellar evolution. Our morphological
results are broadly consistent with the predictions of stellar evolution if the
progenitors of asymmetric PNs have on average larger masses than the
progenitors of symmetric PNs, without any assumption or relation to binarity of
the stellar progenitors.


title:
Expanding Confusion: common misconceptions of cosmological horizons and
  the superluminal expansion of the Universe

abstract:
  We use standard general relativity to illustrate and clarify several common
misconceptions about the expansion of the Universe. To show the abundance of
these misconceptions we cite numerous misleading, or easily misinterpreted,
statements in the literature. In the context of the new standard Lambda-CDM
cosmology we point out confusions regarding the particle horizon, the event
horizon, the ``observable universe'' and the Hubble sphere (distance at which
recession velocity = c). We show that we can observe galaxies that have, and
always have had, recession velocities greater than the speed of light. We
explain why this does not violate special relativity and we link these concepts
to observational tests. Attempts to restrict recession velocities to less than
the speed of light require a special relativistic interpretation of
cosmological redshifts. We analyze apparent magnitudes of supernovae and
observationally rule out the special relativistic Doppler interpretation of
cosmological redshifts at a confidence level of 23 sigma.


title:
Exploring the Selection of Galaxy Clusters and Groups: An Optical Survey
  for X-ray Dark Clusters

abstract:
  Data from a new, wide field, coincident optical and X-ray survey, the X-ray
Dark Cluster Survey (XDCS) are presented. This survey comprises simultaneous
and independent searches for clusters of galaxies in the optical and X-ray
passbands. Optical cluster detection algorithms implemented on the data are
detailed. Two distinct optically selected catalogues are constructed, one based
on I-band overdensity, the other on overdensities of colour-selected galaxies.
The superior accuracy of the colour-selection technique over that of the single
passband method is demonstrated, via internal consistency checks and comparison
with external spectroscopic redshift information. This is compared with an
X-ray selected cluster catalogue. In terms of gross numbers, the survey yields
185 I-band selected, 290 colour selected and 15 X-ray selected systems,
residing in ~11deg^2 of optical + X-ray imaging. The relationship between
optical richness/ luminosity and X-ray luminosity is examined, by measuring
X-ray luminosities at the positions of our 290 colour-selected systems. Power
law correlations between the optical richness/ luminosity versus X-ray
luminosity are fitted, both exhibiting approximately 0.2 dex of intrinsic
scatter. Interesting outliers in these correlations are discussed in greater
detail. Spectroscopic follow up of a subsample of X-ray underluminous systems
confirms their reality.


title: The Effect of Clouds on Air Showers Observation from Space

abstract:
  Issues relating to extensive air showers observation by a space-borne
fluorescence detector and the effects of clouds on the observations are
investigated using Monte Carlo simulation. The simulations assume the presence
of clouds with varying altitudes and optical depths. Simulated events are
reconstructed assuming a cloud-free atmosphere. While it is anticipated that
auxiliary instruments, such as LIDAR (LIght Detection And Ranging), will be
employed to measure the atmospheric conditions during actual observation, it is
still possible that these instruments may fail to recognize the presence of a
cloud in a particular shower observation. The purpose of this study is to
investigate the effects on the reconstructed shower parameters in such cases.
Reconstruction results are shown for both monocular and stereo detectors and
for the two limiting cases of optically thin, and optically thick clouds.


title: From Molecular Cores to Planet-forming Disks with SIRTF

abstract:
  The SIRTF mission and the Legacy programs will provide coherent data bases
for extra-galactic and Galactic science that will rapidly become available to
researchers through a public archive. The capabilities of SIRTF and the six
legacy programs are described briefly. Then the cores to disks (c2d) program is
described in more detail. The c2d program will use all three SIRTF instruments
(IRAC, MIPS, and IRS) to observe sources from molecular cores to protoplanetary
disks, with a wide range of cloud masses, stellar masses, and star-forming
environments. The SIRTF data will stimulate many follow-up studies, both with
SIRTF and with other instruments.


title: Between Cool Stars and Hot Planets: Origins of Brown Dwarfs

abstract:
  Brown dwarfs, which straddle the mass range between stars and planets, appear
to be common both in the solar neighborhood and in star-forming regions. Their
ubiquity makes the question of their origin an important one both for our
understanding of brown dwarfs themselves as well as for theories on the
formation of stars and planets. Studies of young sub-stellar objects could
provide valuable insight into their formation and early evolution. Here I
report on the latest results from our observational programs at Keck, VLT and
Magellan on the disk and accretion properties of young brown dwarfs. We find
compelling evidence that they undergo a T Tauri phase analogous to that of
their stellar counterparts.


title:
The Dynamical Influence of a Planet at Semimajor Axis 3.4 AU on the Dust
  Around Epsilon Eridani

abstract:
  Precise-Doppler experiments suggest that a massive (m sin i=0.86 M_J) planet
orbits at semimajor axis a=3.4 AU around Epsilon Eridani, a nearby star with a
massive debris disk. The dynamical perturbations from such a planet would mold
the distribution of dust around this star. We numerically integrated the orbits
of dust grains in this system to predict the central dust cloud structure. For
a supply of grains that begin in low-inclination, low-eccentricity orbits at 15
AU, the primary feature of the dust distribution is a pair of dense clumps,
containing dust particles trapped in mean-motion resonances of the form n:1.
These clumps appear to revolve around the star once every two planet
revolutions. Future observations with the IRAM Plateau de Bure Interferometer,
the SMA, or ALMA could detect these clumps, confirming the existence of the
planet and revealing its location.


title: Chemical Abundances in the Damped Lya Systems

abstract:
  I introduce and review the data and analysis techniques used to measure
abundances in the damped Lya systems, quasar absorption-line systems associated
with galaxies in the early Universe. The observations and issues associated
with their abundance analysis are very similar to those of the Milky Way's
interstellar medium. We measure gas-phase abundances and are therefore subject
to the effects of differential depletion. I review the impact of dust depletion
and then present a summary of current results on the age-metallicity relation
derived from damped Lya systems and new results impacting theories of
nucleosynthesis in the early Universe.


title:
Probing X-ray Emitting Plasma with High Resolution Chandra and
  XMM-Newton Spectra

abstract:
  Highlights of interesting astrophysical discoveries are reviewed in the
context of high resolution X-ray spectroscopy made possible with Chandra and
XMM-Newton, and its relevance to atomic physics calculations and measurements
is discussed. These spectra have shown that the overlap between astrophysics
and atomic physics is stronger than ever, as discoveries of new X-ray lines and
edge structure is matching the need for increasingly detailed theoretical
calculations and experimental measurements of atomic data.


title:
Spectroscopic analysis of sdB stars from the ESO Supernova Ia Progenitor
  Survey

abstract:
  We report on the analysis of high-resolution optical spectra for 77 subdwarf
B (sdB) stars from the ESO Supernova Ia Progenitor Survey. Effective
temperature, surface gravity, and photospheric helium abundance are determined
simultaneously by spectral line profile fitting of hydrogen and helium lines,
and are found to be in agreement with previous studies of sdB stars. 24 objects
show spectral signs of a cool companion, being either companion absorption
lines or a flux contribution at Halpha. Five stars with relatively high
luminosity show peculiar Halpha profiles, possibly indicating stellar winds.
Our results are compared to recent theoretical simulations by Han et al. (2003)
for the distribution in effective temperature and surface gravity, and are
found to agree very well with these calculations. Finally we present a binary
system consisting of two helium-rich hot subdwarfs.


title:
The Turbulent Interstellar Medium: Insights and Questions from Numerical
  Models

abstract:
  "The purpose of numerical models is not numbers but insight." (Hamming) In
the spirit of this adage, and of Don Cox's approach to scientific speaking, we
discuss the questions that the latest generation of numerical models of the
interstellar medium raise, at least for us. The energy source for the
interstellar turbulence is still under discussion. We review the argument for
supernovae dominating in star forming regions. Magnetorotational instability
has been suggested as a way of coupling disk shear to the turbulent flow.
Models make evident that the unstable wavelengths are very long compared to
thermally unstable wavelengths, with implications for star formation in the
outer galaxy and low surface brightness disks. The perennial question of the
factors determining the hot gas filling factor in a SN-driven medium remains
open, in particular because of the unexpectedly strong turbulent mixing at the
boundaries of hot cavities seen in the models. The formation of molecular
clouds in the turbulent flow is also poorly understood. Dense regions suitable
for cloud formation clearly form even in the absence of self-gravity, although
their ultimate evolution remains to be computed.


title:
Gravitational microlensing of quasar broad line regions at large optical
  depths

abstract:
  Recent estimates of the scale of structures at the heart of quasars suggest
that the region responsible for the broad line emission are smaller than
previously thought. With this revision of scale, the broad line region is
amenable to the influence of gravitational microlensing. This study
investigates the influence on microlensing at high optical depth on a number of
current models of the Broad Line Region (BLR). It is found that the BLR can be
significantly magnified by the action of microlensing, although the degree of
magnification is dependent upon spatial and kinematic structure of the BLR.
Furthermore, while there is a correlation between the microlensing fluctuations
of the continuum source and the BLR, there is substantial scatter about this
relation, revealing that broadband photometric monitoring is not necessarily a
guide to microlensing of the BLR. The results of this study demonstrate that
the spatial and kinematic structure within the BLR may be determined via
spectroscopic monitoring of microlensed quasars.


title:
Spectroscopic identification of DENIS-selected brown dwarf candidates in
  the Upper Scorpius OB association

abstract:
  We present low-resolution (R=900) optical (576.1--1,051.1 nm) spectroscopic
observations of 40 candidate very low-mass members in the Upper Scorpius OB
association. These objects were selected using the $I$, $J$ and $K$ photometry
available in the DENIS database. We have derived spectral types and we have
measured H$\alpha$ and NaI doublet (at 818.3 and 819.5 nm) equivalent widths.
We assess the youth of the objects by comparing them to their older
counterparts of similar spectral type in the Pleiades cluster and the field.
Our analysis indicates that 28 of our targets are young very low-mass objects,
and thus they are strong candidate members of the OB association. The other 12
DENIS sources are foreground M dwarfs or background red giants. Our sample of
spectroscopic candidate members includes 18 objects with spectral types in the
range M6.5 and M9, which are likely young brown dwarfs. We classify these
candidates as accreting/non accreting using the scheme proposed by Barrado y
Navascu\'es & Mart\'\i n (2003). We find 5 substellar-mass candidate cluster
members that are still undergoing mass accretion, indicating that the timescale
for accretion onto brown dwarfs can be as long as 5 Myr in some cases.


title: The XMM-Newton Iron Line Profile of NGC 3783

abstract:
  We report on observations of the iron K line in the nearby Seyfert 1 galaxy,
NGC 3783, obtained in a long, 2 orbit (240 ks) XMM-Newton observation. The line
profile obtained exhibits two strong narrow peaks at 6.4 keV and at 7.0 keV,
with measured line equivalent widths of 120 and 35 eV respectively. The 6.4 keV
emission is the K-alpha line from near neutral Fe, whilst the 7.0 keV feature
probably originates from a blend of the neutral Fe K-beta line and the H-like
line of Fe at 6.97 keV. The relatively narrow velocity width of the K-alpha
line (<5000 km/s), its lack of response to the continuum emission on short
timescales and the detection of a neutral Compton reflection component are all
consistent with a distant origin in Compton-thick matter such as the putative
molecular torus. A strong absorption line from highly ionized iron (at 6.67
keV) is detected in the time-averaged iron line profile, whilst the depth of
the feature appears to vary with time, being strongest when the continuum flux
is higher. The iron absorption line probably arises from the highest ionization
component of the known warm absorber in NGC 3783, with an ionization of logxi=3
and column density of 5x10^{22}cm{-2} and may originate from within 0.1pc of
the nucleus. A weak red-wing to the iron K line profile is also detected below
6.4 keV. However when the effect of the highly ionized warm absorber on the
underlying continuum is taken into account, the requirement for a relativistic
iron line component from the inner disk is reduced.


title:
Near-infrared flares from accreting gas around the supermassive black
  hole at the Galactic Centre

abstract:
  Recent measurements of stellar orbits provide compelling evidence that the
compact radio source Sagittarius A* at the Galactic Centre is a
3.6-million-solar-mass black hole. Sgr A* is remarkably faint in all wavebands
other than the radio region, however, which challenges current theories of
matter accretion and radiation surrounding black holes. The black hole's
rotation rate is not known, and therefore neither is the structure of
space-time around it.Here we report high-resolution infrared observations of
Sgr A* that reveal 'quiescent' emission and several flares. The infrared
emission originates from within a few milliarcseconds of the black hole, and
traces very energetic electrons or moderately hot gas within the innermost
accretion region. Two flares exhibit a 17-minute quasi-periodic variability. If
the periodicity arises from relativistic modulation of orbiting gas, the
emission must come from just outside the event horizon, and the black hole must
be rotating at about half of the maximum possible rate.


title:
Stability of a cosmological model with dynamical cancellation of vacuum
  energy

abstract:
  The stability of cosmological solutions in the recently suggested specific
mechanism of dynamical compensation of vacuum energy is studied. It is found
that the solutions in the original version lead to cosmological singularity
which could be reached in final (and short) time. A modification of the
interaction of the compensating field with gravity is suggested which allows to
escape such singularity. It is shown that generic cosmological solution in this
model tends to the Friedmann expansion regime even starting from initially
large vacuum energy.


title:
A Millennium Scale Sunspot Number Reconstruction: Evidence For an
  Unusually Active Sun Since the 1940's

abstract:
  The extension of the sunspot number series backward in time is of
considerable interest for dynamo theory, solar, stellar, and climate research.
We have used records of the Be-10 concentration in polar ice to reconstruct the
average sunspot activity level for the period between the year 850 to the pr
esent. Our method uses physical models for processes connecting the Be-10
concentration with the sunspot number. The reconstruction shows reliably that
the period of high solar activity during the last 60 years is unique throughout
the past 1150 years. This nearly triples the time interval for which such a
statement could be made previously


title: Large-scale magnetic fields from inflation in dilaton electromagnetism

abstract:
  The generation of large-scale magnetic fields is studied in dilaton
electromagnetism in inflationary cosmology, taking into account the dilaton's
evolution throughout inflation and reheating until it is stabilized with
possible entropy production. It is shown that large-scale magnetic fields with
observationally interesting strength at the present time could be generated if
the conformal invariance of the Maxwell theory is broken through the coupling
between the dilaton and electromagnetic fields in such a way that the resultant
quantum fluctuations in the magnetic field has a nearly scale-invariant
spectrum. If this condition is met, the amplitude of the generated magnetic
field could be sufficiently large even in the case huge amount of entropy is
produced with the dilution factor $\sim 10^{24}$ as the dilaton decays.


title: Density field in extended Lagrangian perturbation theory

abstract:
  We analyzed the performance of a perturbation theory for nonlinear
cosmological dynamics, based on the Lagrangian description of hydrodynamics. In
our previous paper, we solved hydrodynamic equations for a self-gravitating
fluid with pressure, given by a polytropic equation of state, using a
perturbation method. Then we obtained the first-order solutions in generic
background universes and the second-order solutions for a wider range of
polytrope exponents. Using these results, we describe density fields with
scale-free spectrum, SCDM, and LCDM models. Then we analyze cross-correlation
coefficient of the density field between N-body simulation and Lagrangian
linear perturbation theory, and the probability distribution of density
fluctuation. From our analyses, for scale-free spectrum models, the case of the
polytrope exponent 5/3 shows better performance than the Zel'dovich
approximation and the truncated Zel'dovich approximation in a quasi-nonlinear
regime. On the other hand, for SCDM and LCDM models, improvement by the effect
of the velocity dispersion was small.


title:
Low mass AGB stellar models for 0.003 < Z < 0.02: basic formulae for
  nucleosynthesis calculations

abstract:
  We have extended our published set of low mass AGB stellar models to lower
metallicity. Different mass loss rates have been explored. Interpolation
formulae for luminosity, effective temperature, core mass, mass of dredge up
material and maximum temperature in the convective zone generated by thermal
pulses are provided. Finally, we discuss the modifications of these quantities
as obtained when an appropriate treatment of the inward propagation of the
convective instability, caused by the steep rise of the radiative opacity
occurring when the convective envelope penetrates the H-depleted region, is
taken into account.


title:
Gamma-ray lines from cosmic-ray interactions with interstellar dust
  grains

abstract:
  As pointed out by Lingenfelter and Ramaty (1977), the shapes of some
gamma-ray lines produced by cosmic-ray interactions with the interstellar
medium potentially contain valuable information on the physical properties of
dust grains, including their compositions and size distributions. The most
promising of such lines are at 847, 1369, 1779 and 6129 keV, from 56-Fe*,
24-Mg*, 28-Si* and 16-O*, respectively. We performed detailed calculations of
their profiles using, in particular, available laboratory measurements combined
with optical model calculations to evaluate the energy distributions of the
recoiling excited nuclei. We show that the line shapes are mainly sensitive to
relatively large interstellar grains, with radii greater than 0.25 microns.
Line fluxes from the inner Galaxy are then predicted.


title: On the Iron content in rich nearby Clusters of Galaxies

abstract:
  In this paper we study the iron content of a sample of 22 nearby hot clusters
observed with BeppoSAX. We find that the global iron mass of clusters is
tightly related to the cluster luminosity and that the relatively loose
correlation between the iron mass and the cluster temperature follows from the
combination of the iron mass vs. luminosity and luminosity vs. temperature
correlations. The iron mass is found to scale linearly with the intracluster
gas mass, implying that the global iron abundance in clusters is roughly
constant. This result suggests that enrichment mechanisms operate at a similar
rate in all clusters. By employing population synthesis and chemical enrichment
models, we show that the iron mass associated to the abundance excess which is
always found in the centre of cool core clusters can be entirely produced by
the brightest cluster galaxy (BCG), which is always found at the centre of cool
core clusters. The iron mass associated to the excess, the optical magnitude of
the BCG and the temperature of the cluster are found to correlate with one
another suggesting a link between the properties of the BCG and the hosting
cluster. These observational facts lends strength to current formation theories
which envisage a strong connection between the formation of the giant BCG and
its hosting cluster.


title: Holes and high velocity HI in NGC 6946

abstract:
  We are studying the properties of the holes and the high velocity gas in NGC
6946. Here we present some puzzling results.


title:
Approximate angular diameter distance in a locally inhomogeneous
  universe with nonzero cosmological constant

abstract:
  We discuss the general and approximate angular diameter distance in the
Friedman-Robertson-Walker cosmological models with nonzero cosmological
constant. We modify the equation for the angular diameter distance by taking
into account the fact that locally the distribution of matter is non
homogeneous. We present exact solutions of this equation in a few special
cases. We propose an approximate analytic solution of this equation which is
simple enough and sufficiently accurate to be useful in practical applications.


title: Estimating N-Point Correlation Functions from Pixelized Sky Maps

abstract:
  We develop, implement and test a set of algorithms for estimating N-point
correlation functions from pixelized sky maps. These algorithms are slow, in
the sense that they do not break the O(N_pix^N) barrier, and yet, they are fast
enough for efficient analysis of data sets up to several hundred thousand
pixels. The typical application of these methods is Monte Carlo analysis using
several thousand realizations, and therefore we organize our programs so that
the initialization cost is paid only once. The effective cost is then reduced
to a few additions per pixel multiplet (pair, triplet etc.). Further, the
algorithms waste no CPU time on computing undesired geometric configurations,
and, finally, the computations are naturally divided into independent parts,
allowing for trivial (i.e., optimal) parallelization.


title:
Disc-planet, planet-planet, and star-planet interactions during planet
  formation

abstract:
  In this article we present results from three on-going projects related to
the formation of protoplanets in protostellar discs. We present the results of
simulations that model the interaction between embedded protoplanets and disc
models undergoing MHD turbulence. We review the similarities and differences
that arise when the disc is turbulent as opposed to laminar (but viscous), and
present the first results of simulations that examine the tidal interaction
between low mass protoplanets and turbulent discs. We describe the results of
simulations of Jovian mass protoplanets forming in circumbinary discs, and
discuss the range of possible outcomes that arise in hydrodynamic simulations.
Finally, we report on some preliminary simulations of three protoplanets of
Jovian mass that form approximately coevally within a protostellar disc. We
describe the conditions under which such a system can form a stable three
planet resonance.


title: Cosmic Ray Acceleration at Relativistic Shocks

abstract:
  Theoretical studies of cosmic ray particle acceleration in the first-order
Fermi process at relativistic shocks are reviewed. At the beginning we discuss
the acceleration processes acting at mildly relativistic shock waves. An
essential role of oblique field configurations and field perturbations in
forming the particle energy spectrum and changing the acceleration time scale
is discussed. Then, we report on attempts to consider particle acceleration at
ultra-relativistic shocks, often yielding an asymptotic spectral index sigma =
2.2 at large shock Lorentz factors. We explain why this result is limited to
the cases of highly turbulent conditions near shocks. We conclude that our
present knowledge of the acceleration processes acting at relativistic shocks
is insufficient to allow for realistic modelling of the real shocks. The
present review is a modified, extended and updated version of Ostrowski (1999).


title: Selection of extragalactic Targets for AO and VLTI Observations

abstract:
  In this contribution we would like to emphasize the usefulness of data mining
multiwavelength surveys like the Sloan Digital Sky Survey (SDSS) or the ROSAT
All Sky Survey (RASS) -- which have become available to the public recently --
in order to find interesting objects suitable for adaptive optics (AO) or
interferometric (VLTI) observations in the infrared. We will present a sample
of extragalactic X-ray sources having an optical counterpart (based on SDSS
data release 1) which are suitable for AO/VLTI observations using a natural
guide star in their vicinity.


title:
Turbulence in the Star-forming Interstellar Medium: Steps toward
  Constraining Theories with Observations

abstract:
  Increasingly sophisticated observational tools and techniques are now being
developed for probing the nature of interstellar turbulence. At the same time,
theoretical advances in understanding the nature of turbulence and its effects
on the structure of the ISM and on star formation are occurring at a rapid
pace, aided in part by numerical simulations. These increased capabilities on
both fronts open new opportunities for strengthening the links between
observation and theory,and for meaningful comparisons between the two.


title:
The high energy tail of gamma-ray burst 941017: Comptonization of
  synchrotron self absorbed photons

abstract:
  The recent detection of an unusually hard spectral component in GRB941017
extending to $\ge200$ MeV is hard to explain as a synchrotron emission from
shock-accelerated electrons.
  It was argued to imply acceleration of protons to ultra-high energy. We show
here that the "high energy tail" can be explained as emission from
shock-accelerated electrons in the early afterglow epoch, taking into account
the effect of synchrotron self-absorption. High energy observations set in this
case stringent constraints on model parameters: A lower limit to the total
explosion energy $E\gsim5 \times 10^{53}$ erg (assuming spherical symmetry);
  An upper limit to the density of gas surrounding the explosion,
  $n\lsim10^{-2}(E/10^{54}{\rm erg}){\rm cm}^{-3}$; A lower limit to the
expansion Lorentz factor $\Gamma_i\gsim 200$; and An upper limit to the
fraction of thermal energy carried by the magnetic field behind the shock
driven into the surrounding medium,
  $\epsilon_{B,f} <= 10^{-4}$. Such constraints can not be inferred from
keV--MeV data alone. The unusually low value of $\epsilon_{B,f}$ and the
unusually high ratio $E/n$ may account for the rareness of GRB941017-type high
energy tails. Tighter constraints on model parameters may be obtained in the
future from optical and sub-TeV observations.


title: Supernova Spectra

abstract:
  In this paper are summarized the main advances of the last years in the field
of SN spectra . The arguments against a monodimensional sequence for SNIa are
discussed as well as the efforts to improve the temporal and spectral coverage
of this kind of SNe, with the aim to understand the physics of the explosions
for their use as cosmological distance indicators. Although variety is the main
character of core-collapse SNe, we have been recently surprised by both
exceptionally under- and over-energetic explosions. The main properties of
these two extreme subclasses are here reviewed.


title: Primordial Black Holes as a Probe of Cosmology and High Energy Physics

abstract:
  Recent developments in the study of primordial black holes (PBHs) will be
reviewed, with particular emphasis on their formation and evaporation. PBHs
could provide a unique probe of the early Universe, gravitational collapse,
high energy physics and quantum gravity. Indeed their study may place
interesting constraints on the physics relevant to these areas even if they
never formed.


title: The Space Density of Redshift 5.7 Ly-Alpha Emitters

abstract:
  We present results from a blind, spectroscopic search for redshift 5.7 LyA
emission-line galaxies at Keck I. Using a band-limiting filter and custom
slitmask, the LRIS detector was covered with low resolution spectra in the 8100
- 8250 A atmospheric window which contains no bright night sky emission lines.
Nine objects with line fluxes greater than our flux limit of 6e-18 erg/s/cm2
were found in the ~5.1 square arcminute field. Follow up observations indicate
none of these are z=5.7 LyA emitters -- a result which places strong limits on
evolution scenarios for LyA emitters between redshift 3 and redshift 5.7. In
particular, the paucity of z=5.7 LyA emitters raises the question of whether
the LyA -selected population plays a significant role in maintaining the
ionization of the intergalactic medium at z = 5.7.
  We argue that if the escape fraction of LyA from galaxies is less than $0.4
f_{LyC}$, where $f_{LyC}$ is the escape fraction of Lyman continuum photons,
then the star formation rate in the \lya emitting population is high enough in
the no-evolution model (our upper limit) to maintain the ionization of the IGM
at z=5.7.


title: Luminosity and Redshift Dependence of Quasar Spectral Properties

abstract:
  Using a large sample of quasar spectra from the SDSS, we examine the
composite spectral trends of quasars as functions of both redshift and
luminosity, independently of one another. Aside from the well known Baldwin
effect (BE) -- the decrease of line equivalent width with luminosity -- the
average spectral properties are remarkably similar. Host galaxy contamination
and the BE are the primary causes for apparent changes in the average spectral
slope of the quasars. The BE is detected for most emission lines, including the
Balmer lines, but with several exceptions including NV1240A. Emission line
shifts of several lines are associated with the BE. The BE is mainly a function
of luminosity, but also partly a function of redshift in that line equivalent
widths become stronger with redshift. Some of the complex iron features change
with redshift, particularly near the small blue bump region.


title: The Luminosity Distance in Perturbed FLRW Spacetimes

abstract:
  We derive an expression for the luminosity distance in FLRW spacetimes
affected by scalar perturbations. Our expression is complete to linear order
and is expressed entirely in terms of standard cosmological parameters and
observational quantities. We illustrate the result by calculating the RMS
scatter in the usual luminosity distance in flat (Omega_m,Omega_Lambda) =
(1.0,0.0) and (0.3,0.7) cosmologies. In both cases the scatter is appreciable
at high redshifts, and rises above 11% at z = 2, where it may be the dominant
noise term in the Hubble diagram based on SN Ia.


title: Proper Motion Catalog From SDSS \intersect USNO-B

abstract:
  We present a catalog of 345,000 stars with proper motions \mu > 20 mas/yr and
magnitudes r' <20, drawn from the intersection of the SDSS Data Release One and
USNO-B. We first use SDSS quasars to correct the proper motions in each of the
two source catalogs, finding that these corrections for systematics are
comparable to the statistical errors. The combined proper motions have errors
of \sigma_\mu=4.0 mas/yr, significantly better than any previous catalog at
these magnitudes. While cross-correlating SDSS and USNO-B removes the vast
majority of the very large number of spurious proper-motion stars in each, some
contamination remains, especially at faint magnitudes, r' > 19.5, and high
proper motions. We present a diagrammatic method to estimate the level of
contamination in selected subsets of the catalog, which should be useful for
choosing appropriate selection criteria for various applications.


title:
23 High Redshift Supernovae from the IfA Deep Survey: Doubling the SN
  Sample at z>0.7

abstract:
  We present photometric and spectroscopic observations of 23 high redshift
supernovae spanning a range of z=0.34-1.03, 9 of which are unambiguously
classified as Type Ia. These supernovae were discovered during the IfA Deep
Survey, which began in September 2001 and observed a total of 2.5 square
degrees to a depth of approximately m=25-26 in RIZ over 9-17 visits, typically
every 1-3 weeks for nearly 5 months, with additional observations continuing
until April 2002. We give a brief description of the survey motivations,
observational strategy, and reduction process. This sample of 23 high-redshift
supernovae includes 15 at z>0.7, doubling the published number of objects at
these redshifts, and indicates that the evidence for acceleration of the
universe is not due to a systematic effect proportional to redshift. In
combination with the recent compilation of Tonry et al. (2003), we calculate
cosmological parameter density contours which are consistent with the flat
universe indicated by the CMB (Spergel et al. 2003). Adopting the constraint
that Omega_total = 1.0, we obtain best-fit values of (Omega_m,
Omega_Lambda)=(0.33, 0.67) using 22 SNe from this survey augmented by the
literature compilation. We show that using the empty-beam model for
gravitational lensing does not eliminate the need for Omega_Lambda > 0.
Experience from this survey indicates great potential for similar large-scale
surveys while also revealing the limitations of performing surveys for z>1 SNe
from the ground.


title: Simulating Chandra observations of galaxy clusters

abstract:
  Numerical hydro-N-body simulations are very important tools for making
theoretical predictions for the formation of galaxy clusters. They show that
the atmospheres of clusters of galaxies have quite complex angular and thermal
structures. The full understanding of the physical processes behind these
features can be only achieved by direct comparison of observations to
hydro-N-body simulations. Although simple in principle, these comparisons are
not always trivial. In fact, real data are convolved with the instrument
response which may substantially influence the apparent properties of the
studied features. To overcome this problem we build the software package X-MAS
devoted to simulate X-ray observations of galaxy clusters obtained from
hydro-N-body simulations. In this paper we present how this software package
works and discuss its application to the simulation of Chandra ACIS-S3
observations. We compare some of the main physical properties of the input data
to the ones derived from simulated observations after performing a standard
imaging and spectral analysis. We show that, if the thermal structure of the
cluster along a particular line of sight is quite complex, the projected
spectroscopic temperature obtained from the observation is significantly lower
than the emission-weighed value inferred directly from hydrodynamical
simulation. This implies that much attention must be paid in the theoretical
interpretation of observational temperatures.


title:
Microlensing Candidates in M87 and the Virgo Cluster with the Hubble
  Space Telescope

abstract:
  The position of the giant elliptical galaxy M87 at the center of the Virgo
Cluster means that the inferred column density of dark matter associated with
both the cluster halo and the galaxy halo is quite large. This system is thus
an important laboratory for studying massive dark objects in elliptical
galaxies and galaxy clusters by gravitational microlensing, strongly
complementing the studies of spiral galaxy halos performed in the Local Group.
We have performed a microlensing survey of M87 with the WFPC2 instrument on the
Hubble Space Telescope. Over a period of thirty days, with images taken once
daily, we discover seven variable sources. Four are variable stars of some
sort, two are consistent with classical novae, and one exhibits an excellent
microlensing lightcurve, though with a very blue color implying the somewhat
disfavored possibility of a horizontal branch source being lensed. Based on
sensitivity calculations from artificial stars and from artificial lightcurves,
we estimate the expected microlensing rate. We find that the detection of one
event is consistent with a dark halo with a 20% contribution of microlensing
objects for both M87 and the Virgo Cluster, similar to the value found from
observations in the Local Group. Further work is required to test the
hypothesized microlensing component to the cluster.


title:
The Effect of Proton Temperature Anisotropy on the Solar Minimum Corona
  and Wind

abstract:
  A semi-empirical, axisymmetric model of the solar minimum corona is developed
by solving the equations for conservation of mass and momentum with prescribed
anisotropic temperature distributions. In the high-latitude regions, the proton
temperature anisotropy is strong and the associated mirror force plays an
important role in driving the fast solar wind; the critical point where the
outflow velocity equals the parallel sound speed is reached already at 1.5 Rsun
from Sun center. The slow wind arises from a region with open field lines and
weak anisotropy surrounding the equatorial streamer belt. The model parameters
were chosen to reproduce the observed latitudinal extent of the equatorial
streamer in the corona and at large distance from the Sun. We find that the
magnetic cusp of the closed-field streamer core lies at about 1.95 Rsun. The
transition from fast to slow wind is due to a decrease in temperature
anisotropy combined with the non-monotonic behavior of the non-radial expansion
factor in flow tubes that pass near the streamer cusp. In the slow wind, the
plasma beta is of order unity and the critical point lies at about 5 Rsun, well
beyond the magnetic cusp. The predicted outflow velocities are consistent with
OVI Doppler dimming measurements from UVCS/SOHO. We also find good agreement
with polarized brightness (pB) measurements from LASCO/SOHO and HI Ly-alpha
images from UVCS/SOHO.


title: Big Bang Nucleosynthesis and the Missing Hydrogen Mass in the Universe

abstract:
  It is proposed that when the era of the big-bang nucleosynthesis ended,
almost all of the 75 percent of the observed total baryonic matter remained in
the form of hydrogen and continued to exist in the form of protons and
electrons. They are present today as baryonic dark matter in the form of
intergalactic hydrogen plasma. To test our hypothesis we have investigated the
effects of Thomson scattering by free electrons on the reported dimming of Type
Ia supernovae. The quantitative results of our calculation suggest that the
dimming of these supernovae, which are dimmer than expected and hence more
distant than predicted by Hubble expansion, is a result of Thomson scattering
without cosmic acceleration.


title: Searching For Planetary Transits In The Open Cluster NGC 7789

abstract:
  Open clusters are ideal targets for searching for transiting Hot Jupiters.
They provide a relatively large concentration of stars on the sky and cluster
members have similar metallicities, ages and distances. Fainter cluster members
are likely to show deeper transit signatures, helping to offset sky noise
contributions. A survey of open clusters will then help to characterise the Hot
Jupiter fraction of main sequence stars, and how this may depend on primordial
metallicity and stellar age. We present results from 11 nights of observations
of the open cluster NGC 7789 with the WFC camera on the INT telescope in La
Palma. From 684 epochs, we obtained lightcurves and B-V colours for ~25600
stars, with ~2400 stars with better than 1% precision. We expect to detect ~1
transiting Hot Jupiter in our sample assuming that 1% of stars host a Hot
Jupiter companion.


title: The H$_2^+$ ion in a strong magnetic field. Lowest excited states

abstract:
  As a continuation of our previous work ({\it Phys. Rev. A68, 012504 (2003)})
an accurate study of the lowest $1\si_g$ and the low-lying excited $1\si_u$,
$2\si_g$, $1\pi_{u,g}$, $1\de_{g,u}$ electronic states of the molecular ion
$H_2^+$ is made. Since the parallel configuration where the molecular axis
coincides with the magnetic field direction is optimal, this is the only
configuration which is considered. The variational method is applied and the
{\it same} trial function is used for different magnetic fields. The magnetic
field ranges from $10^9 G$ to $4.414 \times 10^{13} G$ where non-relativistic
considerations are justified. Particular attention is paid to the $1\si_u$
state which was studied for an arbitrary inclination. For this state a
one-parameter vector potential is used which is then variationally optimized.


title:
Comparing Chemical Abundances of the Damped Lya Systems and Metal-Poor
  Stars

abstract:
  I briefly draw comparisons between the fields of damped Lya and metal-poor
stellar abundances. In particular, I examine their complementary
age-metallicity relations and comparisons between the damped Lya and dwarf
galaxy abundance patterns. Regarding the latter, I describe a series of
problems concerning associating high z damped Lya systems with present-day
dwarfs.


title:
The Role of Gas in the Merging of Massive Black Holes in Galactic
  Nuclei. I. Black Hole Merging in a Spherical Gas Cloud

abstract:
  Using high-resolution SPH numerical simulations, we investigate the effects
of gas on the inspiral and merger of a massive black hole binary. This study is
motivated by both observational and theoretical work that indicate the presence
of large amounts of gas in the central regions of merging galaxies. N-body
simulations have shown that the coalescence of a massive black hole binary
eventually stalls in a stellar background. However, our simulations suggest
that the massive black hole binary will finally merge if it is embedded in a
gaseous background. Here we present results in which the gas is assumed to be
initially spherical with a relatively smooth distribution. In the early
evolution of the binary, the separation dimishes due to the gravitational drag
exerted by the background gas. In the later stages, when the binary dominates
the gravitational potential in its vicinity, the medium responds by forming an
ellipsoidal density enhancement whose axis lags behind the binary axis, and
this offset produces a torque on the binary that causes continuing loss of
angular momentum and is able to reduce the binary separation to distances where
gravitational radiation is efficient. Assuming typical parameters from
observations of Ultra Luminous Infrared Galaxies, we predict that a black hole
binary will merge within $10^{7}$yrs; therefore these results imply that in a
merger of gas-rich galaxies, any massive central black holes will coalescence
soon after the galaxies merge. Our work thus supports scenarios of massive
black hole evolution and growth where hierarchical merging plays an important
role. The final coalescence of the black holes leads to gravitational radiation
emission that would be detectable up to high redshift by LISA. We show that
similar physical effects are important for the formation of close binary stars.


title:
A Comprehensive Study of the X-ray Bursts from the Magnetar Candidate 1E
  2259+586

abstract:
  We present a statistical analysis of the X-ray bursts observed from the 2002
June 18 outburst of the Anomalous X-ray Pulsar (AXP) 1E 2259+586, observed with
the Proportional Counter Array (PCA) aboard the Rossi X-ray Timing Explorer. We
show that the properties of these bursts are similar to those of Soft
Gamma-Repeaters (SGRs). The similarities we find are the burst durations follow
a log-normal distribution which peaks at 99 ms, the differential burst fluence
distribution is well described by a power law of index -1.7, the burst fluences
are positively correlated with the burst durations, the distribution of waiting
times is well described by a log-normal distribution of mean 47 s, and the
bursts are generally asymmetric with faster rise than fall times. However, we
find several quantitative differences between the AXP and SGR bursts.
Specifically, the AXP bursts we observed exhibit a wider range of durations,
the correlation between burst fluence and duration is flatter than for SGRs,
the observed AXP bursts are on average less energetic than observed SGR bursts,
and the more energetic AXP bursts have the hardest spectra -- the opposite of
what is seen for SGRs. We conclude that the bursts are sufficiently similar
that AXPs and SGRs can be considered united as a source class yet there are
some interesting differences that may help determine what physically
differentiates the two closely related manifestations of neutron stars.


title: Formalism for the Subhalo Mass Function in the Tidal-limit Approximation

abstract:
  We present a theoretical formalism by which the global and the local mass
functions of dark matter substructures (dark subhalos) can be analytically
estimated. The global subhalo mass function is defined to give the total number
density of dark subhalos in the universe as a function of mass, while the local
subhalo mass function counts only those subhalos included in one individual
host halo. We develop our formalism by modifying the Press-Schechter theory to
incorporate the followings: (i) the internal structure of dark halos; (ii) the
correlations between the halos and the subhalos; (iii) the subhalo mass-loss
effect driven by the tidal forces. We find that the resulting (cumulative)
subhalo mass function is close to a power law with the slope of ~ -1, that the
subhalos contribute approximately 10 % of the total mass, and that the tidal
stripping effect changes the subhalo mass function self-similarly, all
consistent with recent numerical detections.


title: Ultraviolet Emission from the Millisecond Pulsar J0437-4715

abstract:
  We observed PSR J0437-4715 with the FUV-MAMA detector of the Hubble Space
Telescope Imaging Spectrometer (STIS) to measure the pulsar's spectrum and
pulsations. For the first time, UV emission from a millisecond pulsar is
detected. The measured flux, $(2.0\pm 0.2)\times 10^{-15}$ erg s$^{-1}$
cm$^{-2}$ in the 1150-1700 \AA range, corresponds to the luminosity $L_{\rm
FUV}=(4.7\pm 0.5)\times 10^{27}$ erg s$^{-1}$, for the distance of 140 pc and
negligible interstellar extinction. The shape of the observed spectrum suggests
thermal emission from the neutron star surface with a surprisingly high
temperature of about $1\times 10^5$ K, above the upper limit on the surface
temperature of the younger ``ordinary'' pulsar J0108-1431. For the few-Gyr-old
J0437-4715, such a temperature requires a heating mechanism to operate. The
spectrum of J0437-4715 shows marginal evidence of an emission line at 1372 \AA,
which might be a gravitationally redshifted Zeeman component of the Hydrogen
Ly$\alpha$ line in a magnetic field $\sim 7\times 10^8$ G.
  No pulsations are detected, with a $3\sigma$ upper limit of 50% on pulsed
fraction.


title:
WIYN Open Cluster Study. XIX. Main Sequence Fitting Distances to Open
  Clusters Using V-K Color-Magnitude Diagrams

abstract:
  We have combined existing optical magnitudes for stars in seven open clusters
and 54 field stars with the corresponding JHKs photometry from the Two Micron
All Sky Survey (2MASS). Combining optical with near-IR photometry broadens the
color baseline minimizing the influence of photometric errors and allows better
discrimination between cluster stars and contaminating foreground and
background populations. The open clusters in this study include NGC 2516, M35,
M34, NGC 3532, M37, M67, and NGC 188. The field stars we are using possess high
quality Hipparcos parallaxes and well-determined metal abundances allowing us
to empirically determine the dependence of (V-K) color on metal abundance in
the range -0.45<=[Fe/H]<=+0.35. Using this relation along with the parallaxes
of the field stars, we are able to construct an unevolved main sequence in the
[Mv,(V-K)o] diagram for a specific abundance. These diagrams are then used to
fit to the cluster main sequences in the [V,V-K] color-magnitude diagram in
order to estimate a distance for each open cluster. We find that the resultant
distances are within the range of distances found in the literature via the
main sequence fitting technique. It is hoped that this will spur an expansion
of the current (limited) database of star clusters with high quality (V-K)
photometry down to the unevolved main sequence.


title: Correlated Hybrid Fluctuations from Inflation with Thermal Dissipation

abstract:
  We investigate the primordial scalar perturbations in the thermal dissipative
inflation where the radiation component (thermal bath) persists and the density
fluctuations are thermally originated. The perturbation generated in this model
is hybrid, i.e. it consists of both adiabatic and isocurvature components. We
calculate the fractional power ratio ($S$) and the correlation coefficient
($\cos\Delta$) between the adiabatic and the isocurvature perturbations at the
commencing of the radiation regime. Since the adiabatic/isocurvature
decomposition of hybrid perturbations generally is gauge-dependent at
super-horizon scales when there is substantial energy exchange between the
inflaton and the thermal bath, we carefully perform a proper decomposition of
the perturbations. We find that the adiabatic and the isocurvature
perturbations are correlated, even though the fluctuations of the radiation
component is considered uncorrelated with that of the inflaton. We also show
that both $S$ and $\cos \Delta$ depend mainly on the ratio between the
dissipation coefficient $\Gamma$ and the Hubble parameter $H$ during inflation.
The correlation is positive ($\cos\Delta > 0$) for strong dissipation cases
where $\Gamma/H >0.2$, and is negative for weak dissipation instances where
$\Gamma/H <0.2$. Moreover, $S$ and $\cos \Delta$ in this model are not
independent of each other. The predicted relation between $S$ and $\cos\Delta$
is consistent with the WMAP observation. Other testable predictions are also
discussed.


title: The Neutral ISM in Nearby Luminous Compact Blue Galaxies

abstract:
  We observed 20 nearby Luminous Compact Blue Galaxies (LCBGs) in HI and
CO(J=2-1) with the GBT and JCMT. These ~L^star galaxies are blue, high surface
brightness, starbursting, high metallicity galaxies with an underlying older
stellar population. They are common at z~1, but rare in the local Universe. It
has been proposed that intermediate redshift LCBGs may be the progenitors of
local dwarf ellipticals or low luminosity spirals, or that they may be more
massive disks forming from the center outward to become L^star galaxies. To
discriminate among various possible evolutionary scenarios, we have measured
the dynamical masses and gas depletion time scales of this sample of nearby
LCBGs.
  We find that local LCBGs span a wide range of dynamical masses, from 4 x 10^9
to 1 x 10^11 M_solar (measured within R_25). Molecular gas in local LCBGs is
depleted quite quickly, in 30 to 200 million years. The molecular plus atomic
gas is depleted in 30 million to 10 billion years; however, ~80% of the local
LCBGs deplete their gas in less than 5 billion years. As LCBGs are
heterogeneous in both dynamical mass and gas depletion time scales, they are
not likely to evolve into one homogeneous galaxy class.


title:
Monte-Carlo Modeling of Non-Gravitational Heating Processes in Galaxy
  Clusters

abstract:
  We consider non-gravitational heating effects on galaxy clusters on the basis
of the Monte-Carlo modeling of merging trees of dark matter halos combined with
the thermal evolution of gas inside each halo. Under the assumption of
hydrostatic equilibrium and the isothermal gas profiles, our model takes
account of the metallicity evolution, metallicity-dependent cooling of gas,
supernova energy feedback, and heating due to jets of radio galaxies in a
consistent manner. The observed properties of galaxy clusters can be explained
in models with higher non-gravitational heating efficiency than that in the
conventional model. Possibilities include jet heating by the Fanaroff-Riley
Type II radio galaxies, and the enhanced star formation efficiency and/or
supernova energy feedback, especially at high redshifts.


title: Supernova Statistics

abstract:
  The statistics of SN discoveries is used to reveal selection biases of past
and current SN searches and to gain insight on the progenitor scenarios for the
different SN types. We also report estimates of the SN rate per unit mass in
galaxies of different types and on the first attempts to study the evolution of
the supernova rate with redshift.


title:
Evidence for a fundamental stellar upper mass limit from clustered star
  formation

abstract:
  The observed masses of the most massive stars do not surpass about 150Msun.
This may either be a fundamental upper mass limit which is defined by the
physics of massive stars and/or their formation, or it may simply reflect the
increasing sparsity of such very massive stars so that observing even
higher-mass stars becomes unlikely in the Galaxy and the Magellanic Clouds. It
is shown here that if the stellar initial mass function (IMF) is a power-law
with a Salpeter exponent (alpha=2.35) for massive stars then the richest very
young cluster R136 seen in the Large Magellanic Cloud (LMC) should contain
stars with masses larger than 750Msun. If, however, the IMF is formulated by
consistently incorporating a fundamental upper mass limit then the observed
upper mass limit is arrived at readily even if the IMF is invariant. An
explicit turn-down or cutoff of the IMF near 150Msun is not required; our
formulation of the problem contains this implicitly. We are therefore led to
conclude that a fundamental maximum stellar mass near 150Msun exists, unless
the true IMF has alpha>2.8.


title: The spectra of short Gamma-Ray Bursts

abstract:
  We present the results of the spectral analysis of a sample of short bright
$\gamma$--ray bursts (GRB) detected by BATSE and compare them with the average
and time resolved spectral properties of long bright bursts. While the spectral
parameters of short GRBs confirm, as expected from previous works based on the
hardness ratio, that they are harder than long events, we find that this
difference is mainly due to a harder low energy spectral component present in
short bursts, rather than to a (marginally) different peak energy. Intriguingly
our analysis also reveals that the emission properties of short GRBs are
similar to the first 2 s of long events. This might suggest that the central
engine of long and short GRBs is the same, just working for a longer time for
long GRBs. We find that short bursts do not obey the correlation between peak
frequency and isotropic emitted energy for any assumed redshift, while they can
obey the similar correlation between the peak frequency and isotropic emitted
luminosity. This is consistent with (although not a proof of) the idea that
short GRBs emit a $\gamma$--ray luminosity similar to long GRBs. If they indeed
obey the peak frequency -- isotropic luminosity relation, we can estimate the
redshift distribution of short bursts, which turns out to be consistent with
that of long bursts just with a slightly smaller average redshift.


title:
Confirmation of strong magnetic field amplification and nuclear cosmic
  ray acceleration in SN 1006

abstract:
  It is shown that the nonlinear kinetic model of cosmic ray (CR) acceleration
in supernova remnants (SNRs) fits the shell-type nonthermal X-ray morphology,
obtained in Chandra observations, in a satisfactory way. The set of empirical
parameters is the same which reproduces the dynamical properties of the SNR and
the spectral characteristics of the emission produced by CRs. The extremely
small spatial scales of the observed X-ray distribution are due to the large
effective magnetic field $B_{\mathrm d}\sim 100$ $\mu$G in the interior, which
is also required to give a good fit for the spatially integrated radio and
X-ray synchrotron spectra. The only reasonably thinkable condition for the
production of such a large effective field strength is an efficiently
accelerated nuclear CR component. Therefore the Chandra data confirm the
inference that SN 1006 indeed accelerates nuclear CRs with the high efficiency
required for SNRs to be considered as the main Galactic CR sources.


title: Spectroscopic diagnostic for the mineralogy of large dust grains

abstract:
  We examine the thermal infrared spectra of large dust grains of different
chemical composition and mineralogy. Strong resonances in the optical
properties result in detectable spectral structure even when the grain is much
larger than the wavelength at which it radiates. We apply this to the thermal
infrared spectra of compact amorphous and crystalline silicates. The weak
resonances of amorphous silicates at 9.7 and 18 micron virtually disappear for
grains larger than about 10 micron. In contrast, the strong resonances of
crystalline silicates produce emission dips in the infrared spectra of large
grains; these emission dips are shifted in wavelength compared to the emission
peaks commonly seen in small crystalline silicate grains. We discuss the effect
of a fluffy or compact grain structure on the infrared emission spectra of
large grains, and apply our theory to the dust shell surrounding Vega.


title:
WZ Sge: HST Spectroscopy of the Cooling of the White Dwarf after the
  2001 Outburst

abstract:
  Following an outburst in 2001 July, the UV flux of WZ Sge has declined slowly
toward pre-outburst levels. Here, we describe new 1150-1710 Angstrom HST/STIS
spectra of WZ Sge obtained between 2002 April and 2003 March to follow the
decline. A combined analysis of these and spectra obtained in the fall of 2001
show that if log g=8.5, then the white dwarf temperature decreased from 23,400
K in 2001 October, shortly after the steady decline of the system began, to
15,900 K 17 months later. The UV flux in 2003 March was still 2.4 times higher
than measured prior to the outburst and so the system was still recovering from
the outburst. During this period, the shape of the spectrum and the flux from
the system are consistent with a log g=8.5, 0.9 solar mass white dwarf at the
astrometrically-determined distance to WZ Sge. Although the spectrum from 2001
September resembles that of a white dwarf with a temperature of 28,200 K, the
implied radius is smaller than in the remainder of the observations. If the
entire white dwarf was visible in 2001 September, then either a second
component, such as the disk emission, was distorting the spectrum, or more
likely, the temperature on the white dwarf photosphere was not uniform then.
The metal lines in the spectra of WZ Sge have weakened with time. Model fits
that allow for material along the line of sight to the white dwarf photosphere
are substantial improvements over models which assume all the lines arise from
the photosphere. This obviates the need to explain very unusual abundance
ratios in the photosphere and complicates the determination of the rotation
rate of the white dwarf.


title:
Low-Metallicity Blue Compact Dwarfs as Templates for Primordial Star
  Formation

abstract:
  Understanding how galaxies formed their first stars is a vital cosmological
question, but the study of high-redshift objects, caught in the act of forming
their first stars, is difficult. Here we argue that two extremely
low-metallicity Blue Compact Dwarf galaxies (BCDs), IZw18 and SBS0335-052,
could be local templates for primordial star formation, since both lack evolved
($> $1 Gyr) stellar populations; but they form stars differently.


title:
Hints of star fomation at z>6: the chemical abundances of the DLA system
  in the QSO BRI 1202-0725 (z_abs = 4.383)

abstract:
  The Damped Ly-alpha (DLA) absorber at redshift z_abs=4.383 observed toward
QSO BRI 1202-0725 is studied by means of high resolution (FWHM ~ 7 km/s)
VLT-UVES spectra. We refine a previously determined Si abundance and derive
with confidence abundances for C, N and O which are poorly known in DLAs. The
[O/Fe] ratio is ~0.6, but we cannot establish if iron is partially locked into
dust grains. The [C/Fe]=0.08 \pm 0.13 and [Si/C]=0.31 \pm 0.07. [N/O] and
[N/Si] are about -1, which is consistent with the majority of DLAs. This value
is much larger than the one observed for the DLA toward QSO J0307-4945 at
z_abs= 4.466. The current interpretation of the bimodal distribution of N
abundances in DLAs implies that large [N/alpha] values correspond to relatively
old systems. Adopting a scale time of 500 Myrs for full N production by
intermediate mass stars, the onset of star formation in our DLA took place
already at redshift z> 6.


title:
Detection of highly ionized O and Ne absorption lines in the X-ray
  spectrum of 4U1820-303 in the globular cluster, NGC 6624

abstract:
  We searched for absorption lines of highly ionized O and Ne in the energy
spectra of two Low-mass X-ray binaries, 4U1820-303 in the globular cluster
NGC6624 and Cyg X-2, observed with the Chandra LETG, and detected O VII, O VIII
and Ne IX absorption lines for 4U1820-303. The equivalent width of the O VII K
alpha line was 1.19 +0.47/-0.30 eV (90 % errors) and the significance was 6.5
sigma. Absorption lines were not detected for Cyg X-2 with a 90 % upper limit
on the equivalent width of 1.06 eV for O VII K alpha. The absorption lines
observed in 4U1820-303 are likely due to hot interstellar medium, because O
will be fully photo-ionized if the absorbing column is located close to the
binary system. The velocity dispersion is restricted to b = 200 - 420 km/s from
consistency between O VII K alpha and K beta lines, Ne/O abundance ratio, and H
column density. The average temperature and the O VII density are respectively
estimated to be log(T[K]) = 6.2 - 6.3 and n(OVII) = (0.7 - 2.3) x 10^{-6}
cm^{-3}. The difference of O VII column densities for the two sources may be
connected to the enhancement of the soft X-ray background (SXB) towards the
Galactic bulge region. Using the polytrope model of hot gas to account for the
SXB we corrected for the density gradient and estimated the midplane O VII
density at the solar neighborhood. The scale height of hot gas is then
estimated using the AGN absorption lines. It is suggested that a significant
portion of both the AGN absorption lines and the high-latitude SXB emission
lines can be explained by the hot gas in our Galaxy.


title: The mass distribution in early type disk galaxies

abstract:
  We are studying the mass distribution in a sample of 50 early type spiral
galaxies, with morphological type betweens S0 and Sab and absolute magnitudes
M_B between -18 and -22; they form the massive and high-surface brightness
extreme of the disk galaxy population. Our study is designed to investigate the
relation between dark and luminous matter in these systems, of which very
little yet is known.
  From a combination of WSRT HI observations and long-slit optical spectra, we
have obtained high-quality rotation curves. The rotation velocities always rise
very fast in the center; in the outer regions, they are often declining, with
the outermost measured velocity 10-25% lower than the maximum.
  We decompose the rotation curves into contributions from the luminous
(stellar and gaseous) and dark matter. The stellar disks and bulges always
dominate the rotation curves within the inner few disk scale lengths, and are
responsible for the decline in the outer parts. As an example, we present here
the decompositions for UGC 9133. We are able to put tight upper and lower
limits on the stellar mass-to-light ratios.


title:
Evolution of self-gravitating magnetized disks. I- Axisymmetric
  simulations

abstract:
  In this paper and a companion work, we report on the first global numerical
simulations of self-gravitating magnetized tori, subject in particular to the
influence of the magnetorotational instability (MRI). In this work, paper I, we
restrict our calculations to the study of the axisymmetric evolution of such
tori. Our goals are twofold: (1) to investigate how self-gravity influences the
global structure and evolution of the disks; and (2) to determine whether
turbulent density inhomogeneities can be enhanced by self-gravity in this
regime.
  As in non self-gravitating models, the linear growth of the MRI is followed
by a turbulent phase during which angular momentum is transported outward. As a
result, self-gravitating tori quickly develop a dual structure composed of an
inner thin Keplerian disk fed by a thicker self-gravitating disk, whose
rotation profile is close to a Mestel disk. Our results show that the effects
of self-gravity enhance density fluctuations much less than they smooth the
disk, and giving it more coherence. We discuss the expected changes that will
occur in 3D simulations, the results of which are presented in a companion
paper.


title:
The Chemical Enrichment History of the Fornax Dwarf Spheroidal Galaxy
  from the Infrared Calcium Triplet

abstract:
  Near infrared spectra were obtained for 117 red giants in the Fornax dwarf
spheroidal galaxy with the FORS1 spectrograph on the VLT, in order to study the
metallicity distribution of the stars and to lift the age-metallicity
degeneracy of the red giant branch (RGB) in the color-magnitude diagram (CMD).
Metallicities are derived from the equivalent widths of the infrared Calcium
triplet lines at 8498, 8542, and 8662 A, calibrated with data from globular
clusters, the open cluster M67 and the LMC. For a substantial portion of the
sample, the strength of the Calcium triplet is unexpectedly high, clearly
indicating that the main stellar population of Fornax is significantly more
metal-rich than could be inferred from the position of its RGB in the CMD. We
show that the relative narrowness of the RGB in Fornax is caused by the
superposition of stars of very different ages and metallicities. The
metallicity distribution in Fornax is centered at [Fe/H]= -0.9, with a
metal-poor tail extending to [Fe/H] ~= -2. While the distribution to higher
metallicities is less well determined by our observations, the comparison with
LMC data indicates that it extends to [Fe/H] ~ -0.4. By comparing the
metallicities of the stars with their positions in the CMD, we have derived the
complex age-metallicity relation of Fornax. In the first few Gyr, the metal
abundance rose to [Fe/H] ~ -1.0 dex. The enrichment accelerated in the past ~
1-4 Gyr to reach [Fe/H] ~ -0.4 dex. More than half the sample is constituted of
star younger than ~ 4 Gyr, thus indicating sustained recent star formation in
Fornax. These results indicate that the capacity of dwarf spheroidal galaxies
to retain the heavy elements that they produce is larger than expected.
(Abridged)


title: Dissipationless collapse of a set of N massive particles

abstract:
  The formation of self-gravitating systems is studied by simulating the
collapse of a set of N particles which are generated from several distribution
functions. We first establish that the results of such simulations depend on N
for small values of N. We complete a previous work by Aguilar and Merritt
concerning the morphological segregation between spherical and elliptical
equilibria. We find and interpret two new segregations: one concerns the
equilibrium core size and the other the equilibrium temperature. All these
features are used to explain some of the global properties of self-gravitating
objects: origin of globular clusters and central black hole or shape of
elliptical galaxies.


title: The Sgr dSph hosts a metal-rich population

abstract:
  We report on abundances of O, Mg, Si, Ca and Fe for 10 giants in the Sgr
dwarf spheroidal derived from high resolution spectra obtained with UVES at the
8.2m Kueyen-VLT telescope. The iron abundance spans the range -0.8 <[Fe/H] <
0.0 and the dominant population is relatively metal-rich with [Fe/H] -0.25. The
alpha/Fe ratios are slightly subsolar, even at the lowest observed
metallicities suggesting a slow or bursting star formation rate. From our
sample of 12 giants (including the two observed by Bonifacio et al 2000) we
conclude that a substantial metal rich population exists in Sgr, which
dominates the sample. The spectroscopic metallicities allow one to break the
age-metallicity degeneracy in the interpretation of the colour-magnitude
diagram (CMD). Comparison of isochrones of appropriate metallicity with the
observed CMD suggests an age of 1 Gyr or younger, for the dominant Sgr
population sampled by us. We argue that the observations support a star
formation that is triggered by the passage of Sgr through the Galactic disc,
both in Sgr and in the disc. This scenario has also the virtue of explaining
the mysterious ``bulge C stars'' as disc stars formed in this event. The
interaction of Sgr with the Milky Way is likely to have played a major role in
its evolution.


title:
The 2dF QSO Redshift Survey - XIII. A Measurement of Lambda from the QSO
  Power Spectrum

abstract:
  We report on measurements of the cosmological constant, Lambda, and the
redshift space distortion parameter beta=Omega_m^0.6/b, based on an analysis of
the QSO power spectrum parallel and perpendicular to the observer's line of
sight, from the final catalogue of the 2dF QSO Redshift Survey. We derive a
joint Lambda - beta constraint from the geometric and redshift-space
distortions in the power spectrum. By combining this result with a second
constraint based on mass clustering evolution, we break this degeneracy and
obtain strong constraints on both parameters. Assuming a flat cosmology and a
Lambda cosmology r(z) function to convert from redshift into comoving distance,
we find best fit values of Omega_Lambda=0.71^{+0.09}_{-0.17} and
beta(z~1.4)=0.45^{+0.09}_{-0.11}. Assuming instead an EdS cosmology r(z) we
find that the best fit model obtained, with Omega_Lambda=0.64^{+0.11}_{-0.16}
and beta(z~1.4)=0.40^{+0.09}_{-0.09}, is consistent with the Lambda r(z)
results, and inconsistent with a Lambda=0 flat cosmology at over 95 per cent
confidence.


title: Elliptical Galaxies: Darkly Cloaked or Scantily Clad?

abstract:
  Planetary nebulae (PNe) may be the most promising tracers in the halos of
early-type galaxies. We have used multi-object spectrographs on the WHT and the
VLT, and the new Planetary Nebula Spectrograph on the WHT, to obtain hundreds
of PN velocities in a small sample of nearby galaxies. These ellipticals show
weak halo rotation, which may be consistent with ab initio models of galaxy
formation, but not with more detailed major merger simulations. The galaxies
near L* show evidence of a universal declining velocity dispersion profile, and
dynamical models indicate the presence of little dark matter within 5 Reff --
implying halos either not as massive or not as centrally concentrated as CDM
predicts.


title: Evolutionary sequences of rotating protoneutron stars

abstract:
  We investigate the evolution of rigidly and differentially rotating
protoneutron stars (PNSs) during the first twenty seconds of their life. We
solve the equations describing stationary axisymmetric configurations in
general relativity coupled to a finite temperature, relativistic equation of
state, to obtain a sequence of quasi-equilibrium configurations describing the
evolution of newly born neutron stars. Our estimates show that the scale of
variation of the angular velocity in a PNSs is of the order of 7-10 km. We
obtain the maximum rotation frequency that can be reached as the protoneutron
stars deleptonizes and cools down, as well as other relevant parameters such as
total angular momentum or |T/W|. Our study shows that imposing physical
constraints (conservation of baryonic mass and angular momentum) and choosing
reasonable thermodynamical profiles as the star evolves gives results
consistent with the energetics of more complex simulations of non-rotating
PNSs. It appears to be unlikely that PNSs formed in nearly axisymmetric core
collapse reach the critical angular velocity to undergo the bar mode
instability. They could, however, undergo secular or low |T/W| rotational
instabilities a few seconds after birth, resulting in a strong emission of
gravitational waves retarded with respect to the neutrino luminosity peak. We
also found that the geometry of strongly differentially rotating protoneutron
stars can become toroidal-like for large values of the angular velocity, before
reaching the mass shedding limit.


title:
Modeling the Heating and Cooling of WZ Sagittae following the July 2001
  Outburst

abstract:
  FUSE and HST/STIS spectra of the dwarf nova WZ Sge, obtained during and
following the early superoutburst of July 2001 over a time span of 20 months,
monitor changes in the components of the system during its different phases.
The synthetic spectral fits to the data indicate a cooling in response to the
outburst of about 12,000K, from about 28,000K down to about 16,000K. The
cooling time scale tau (of the white dwarf temperature excess) is of the order
of about 100 days in the early phase of the cooling period, and increases to
about 850 days toward the end of the second year following the outburst.
  In the present work, we numerically model the accretional heating and
subsequent cooling of the accreting white dwarf in WZ Sge. The best
compressional heating model fit is obtained for a 1.2 Msun white dwarf
accreting at a rate of 9.E-9 Msun/yr for 52 days. However, if one assumes a
lower mass accretion rate or a lower white dwarf mass, then compressional
heating alone cannot account for the observed temperature decline, and other
sources of heating have to be included to increase the temperature of the model
to the observed value. We quantitatively check the effect of boundary layer
irradiation as such an additional source.


title: Nuclear Dynamics and Star Formation of AGN

abstract:
  We are using adaptive optics on Keck and the VLT to probe the dynamics and
star formation in Seyfert and QSO nuclei, obtaining spatial resolutions better
than 0.1" in the H- and K-bands. The dynamics are traced via the 2.12um H_2
1-0S(1) line, while the stellar cluster is traced through the CO 2-0 and 6-3
absorption bandheads at 2.29um and 1.62um respectively. Matching disk models to
the H_2 rotation curves allows us to study nuclear rings, bars, and warps; and
to constrain the mass of the central black hole. The spatial extent and
equivalent width of the stellar absorption permits us to estimate the mass of
stars in the nucleus and their contribution to the emission. Here we report on
new data for I Zwicky 1, Markarian 231, and NGC 7469.


title:
The Structure of the Local Interstellar Medium. II. Observations of D I,
  C II, N I, O I, Al II, and Si II toward Stars within 100 parsecs

abstract:
  Moderate and high-resolution measurements (R ~ 40,000) of interstellar
resonance lines of D I, C II, N I, O I, Al II, and Si II (light ions) are
presented for all available observed targets located within 100 pc which also
have high-resolution observations of interstellar Fe II or Mg II (heavy ions)
lines. All spectra were obtained with the Goddard High Resolution Spectrograph
or the Space Telescope Imaging Spectrograph instruments aboard the Hubble Space
Telescope. Currently, there are 41 sightlines to targets within 100 pc with
observations that include a heavy ion at high resolution and at least one light
ion at moderate or high resolution. We present new measurements of light ions
along 33 of these sightlines, and collect from the literature results for the
remaining sightlines that have already been analyzed. We greatly increase the
number of sightlines with useful LISM absorption line measurements of light
ions by using knowledge of the kinematic structure along a line of sight
obtained from high resolution observations of intrinsically narrow absorption
lines, such as Fe II and Mg II. Because high resolution observations of heavy
ions are critical for understanding the kinematic structure of local absorbers
along the line of sight, we include 18 new measurements of Fe II and Mg II in
an appendix. We present a statistical analysis of the LISM absorption
measurements, which provides an overview of some physical characteristics of
warm clouds in the LISM, including temperature and turbulent velocity. This
complete collection and reduction of all available LISM absorption measurements
provides an important database for studying the structure of nearby warm
clouds, including ionization, abundances, and depletions.


title:
Direct Confirmation of Two Pattern Speeds in the Double Barred Galaxy
  NGC 2950

abstract:
  We present surface photometry and stellar kinematics of NGC 2950, which is a
nearby and undisturbed SB0 galaxy hosting two nested stellar bars. We use the
Tremaine-Weinberg method to measure the pattern speed of the primary bar. This
also permits us to establish directly and for the first time that the two
nested bars are rotating with different pattern speeds, and in particular that
the rotation frequency of the secondary bar is higher than that of the primary
one.


title: Using MgII to investigate quasars and their black-hole masses

abstract:
  We highlight the importance of the MgII emission-line doublet in probing
high-redshift quasars and their supermassive black holes. In the SDSS era,
where large scale investigations of quasars across the age of the Universe are
possible, this emission-line has the ability to provide accurate systemic
redshifts which are important for a variety of follow-up studies, as well as
probe the masses of the supermassive black holes that power these phenomena.


title: Winds and Outflows in Starburst Galaxies and AGN

abstract:
  Winds and outflows in starburst galaxies and AGN provide important
information on the physics of the "central engine", the presence and evolution
of (nuclear) starbursts, and the metal enrichment of the nuclear environment
and the intergalactic medium. Here, we concentrate on two examples, X-ray
observations of the (U)LIRG NGC6240 and the BAL quasar APM08279+5255.


title: Reconstructing the dark energy equation of state with varying alpha

abstract:
  The possibility of reconstructing the dark energy equation of state from
variations in the fine structure constant is investigated for a class of models
where the quintessence field is non-minimally coupled to the electromagnetic
field. For given classes of couplings and quintessence interaction potentials,
it is typically found that variations in alpha would need to be measured to
within an accuracy of at least $5 \times 10^{-7}$ to obtain a reconstructed
equation of state with less than a twenty per cent deviation from the true
equation of state between redshifts 0 and 3. In this case, it is argued that
the sign of the first derivative of the equation of state can be uncovered from
the reconstruction, thus providing unique information on how the universe
developed into its present dark energy dominated phase independent of high
redshift surveys. Such information would complement future observations
anticipated from the Supernova Acceleration Probe.


title: The consequences of nuclear electron capture in core collapse supernovae

abstract:
  The most important weak nuclear interaction to the dynamics of stellar core
collapse is electron capture, primarily on nuclei with masses larger than 60.
In prior simulations of core collapse, electron capture on these nuclei has
been treated in a highly parameterized fashion, if not ignored. With realistic
treatment of electron capture on heavy nuclei come significant changes in the
hydrodynamics of core collapse and bounce. We discuss these as well as the
ramifications for the post-bounce evolution in core collapse supernovae.


title: Intracluster Planetary Nebulae in Clusters and Groups

abstract:
  We present the results from multiple surveys for intracluster planetary
nebulae (IPNe) in nearby galaxy clusters and groups. We find that in the case
of clusters, our observations imply: 1) the amount of intracluster starlight is
significant, up to 20% of the total starlight, 2) the Virgo Cluster is
elongated along our line of sight, and 3) the intracluster light is clustered
on the sky, implying ongoing tidal stripping. In contrast, searches for IPNe in
groups have found little or no intra-group population, implying there may be
something in the cluster environment that significantly enhances intracluster
star production. From high-resolution N-body simulations, we find that the IPNe
should create observable features in position-velocity space, and that these
features may eventually allow us to place limits on the dynamics of galaxy
clusters.


title:
Transient Relativistically-Shifted Lines as a Probe of Black Hole
  Systems

abstract:
  X-ray spectra of Seyfert galaxies have revealed a new type of X-ray spectral
feature, one which appears to offer important new insight into the black hole
system. XMM/Chandra revealed several narrow emission lines redward of Fe Kalpha
in NGC 3516. Since that discovery the phenomenon has been observed in other
Seyfert galaxies, e.g. NGC 7314 and ESO 198-G24. We present new evidence for a
redshifted Fe line in XMM spectra of Mrk 766. These data reveal the first
evidence for a significant shift in the energy of such a line, occurring over a
few tens of kiloseconds. This shift may be interpreted as deceleration of an
ejected blob of gas traveling close to the escape velocity.


title: Black Hole Spin Evolution

abstract:
  We consider a subset of the physical processes that determine the spin j =
a/M of astrophysical black holes. These include: (1) Initial conditions. Recent
models suggest that the collapse of supermassive stars are likely to produce
black holes with j ~ 0.7. (2) Major mergers. The outcome of a nearly equal mass
black hole-black hole merger is not yet known, but we review the current best
guesses and analytic bounds. (3) Minor mergers. We recover the result of
Blandford & Hughes that accretion of small companions with isotropically
distributed orbital angular momenta results in spindown, with j ~ M^{-7/3}. (4)
Accretion. We present new results from fully relativistic magnetohydrodynamic
accretion simulations. These show that, at least for one sequence of flow
models, spin equilibrium (dj/dt = 0) is reached for j ~ 0.9, far less than the
canonical value 0.998 of Thorne that was derived in the absence of MHD effects.
This equilibrium value may not apply to all accretion flows, particularly thin
disks. Nevertheless, it opens the possibility that black holes that have grown
primarily through accretion are not maximally rotating.


title:
Spectroscopic detection of Type Ia Supernovae in the Sloan Digital Sky
  Survey

abstract:
  We present the results of a novel new search of the first data-release from
the Sloan Digital Sky Survey (SDSS-DR1) for the spectra of supernovae. The use
of large spectroscopic galaxy surveys offers the prospect of obtaining improved
estimates of the local supernova rate, with the added benefit of a very
different selection function to that of conventional photometric surveys. In
this Letter we present an overview of our search methodology and the details of
19 Type Ia supernovae found in SDSS--DR1. The supernovae sample is used to make
a preliminary estimate, Gamma_Ia = 0.4 +/- 0.2 h^2 SNu, of the cosmological SNe
rate.


title: Evolution in the Colors of Lyman-Break Galaxies from Z~4 to Z~3

abstract:
  The integrated colors of distant galaxies provide a means for interpreting
the properties of their stellar content. Here, we use rest-frame UV-to-optical
colors to constrain the spectral-energy distributions and stellar populations
of color-selected, B-dropout galaxies at z ~ 4 in the Great Observatories
Origins Deep Survey. We combine the ACS data with ground-based near-infrared
images, which extend the coverage of galaxies at z ~ 4 to the rest-frame
B-band. We observe a color-magnitude trend in the rest-frame m(UV) - B versus B
diagram for the z ~ 4 galaxies that has a fairly well-defined "blue-envelope",
and is strikingly similar to that of color-selected, U-dropout galaxies at z ~
3. We also find that although the co-moving luminosity density at rest-frame UV
wavelengths (1600 Angstroms) is roughly comparable at z ~ 3 and z ~ 4, the
luminosity density at rest-frame optical wavelengths increases by about
one-third from z ~ 4 to z ~ 3. Although the star-formation histories of
individual galaxies may involve complex and stochastic events, the evolution in
the global luminosity density of the UV-bright galaxy population corresponds to
an average star-formation history with a star-formation rate that is constant
or increasing over these redshifts. This suggests that the evolution in the
luminosity density corresponds to an increase in the stellar-mass density of
more than 33%.


title: Optical Identification of Close White Dwarf Binaries in the LISA Era

abstract:
  The Laser Interferometer Space Antenna (LISA) is expected to detect close
white dwarf binaries (CWDBs) through their gravitational radiation. Around 3000
binaries will be spectrally resolved at frequencies > 3 mHz, and their
positions on the sky will be determined to an accuracy ranging from a few tens
of arcminutes to a degree or more. Due to the small binary separation, the
optical light curves of >~ 30% of these CWDBs are expected to show eclipses,
giving a unique signature for identification in follow-up studies of the LISA
error boxes. While the precise optical location improves binary parameter
determination with LISA data, the optical light curve captures additional
physics of the binary, including the individual sizes of the stars in terms of
the orbital separation. To optically identify a substantial fraction of CWDBs
and thus localize them very accurately, a rapid monitoring campaign is
required, capable of imaging a square degree or more in a reasonable time, at
intervals of 10--100 seconds, to magnitudes between 20 and 25. While the
detectable fraction can be up to many tens of percent of the total resolved
LISA CWDBs, the exact fraction is uncertain due to unknowns related to the
white dwarf spatial distribution, and potentially interesting physics, such as
induced tidal heating of the WDs due to their small orbital separation.