title:
Accurate Spectral energy distributions and selection effects for
  high-redshift dusty galaxies: a new hot population to discover with the
  Spitzer Space Telescope?

abstract:
  The spectral energy distributions (SEDs) of dust-enshrouded galaxies with
powerful restframe far-infrared emission have been constrained by a range of
ground-based and space-borne surveys. The IRAS catalog provides a reasonably
complete picture of the dust emission from nearby galaxies (at redshifts of
order 0.1) that are typically less luminous than about 10 to the 12 solar
luminosities. However, at higher redshifts, the observational coverage from all
existing far-IR and submillimeter surveys is much less complete. Here we
investigate the SEDs of a new sample of high-redshift submillimeter-selected
galaxies (SMGs), for which redshifts are known, allowing us to estimate
reliable luminosities and characteristic dust temperatures. We demonstrate that
a wide range of SEDs is present in the population, and that a substantial
number of luminous dusty galaxies with hotter dust temperatures could exist at
similar redshifts (of order 2 to 3), but remain undetected in existing
submillimeter surveys. These hotter galaxies could be responsible for about a
third of the extragalactic IR background radiation at a wavelength of about 100
microns. The brightest of these galaxies would have far-IR luminosities of
order 10 to the 13 solar luminosities and dust temperatures of order 60 K.
Galaxies up to an order of magnitude less luminous with similar SEDs will be
easy to detect and identify in the deepest Spitzer Space Telescope observations
of extragalactic fields at 24 microns.


title: The young stellar population in the Serpens Cloud Core: An ISOCAM survey

abstract:
  We present results from an ISOCAM survey in the two broad band filters LW2
(5-8.5 mu) and LW3 (12-18 mu) of a 0.13 square degree coverage of the Serpens
Main Cloud Core. A total of 392 sources were detected in the 6.7 mu band and
139 in the 14.3 mu band to a limiting sensitivity of ~ 2 mJy. Only about 50% of
the mid-IR excess sources show excesses in the near-IR J-H/H-K diagram. In the
central Cloud Core the Class I/Class II number ratio is 19/18, i.e. about 10
times larger than in other young embedded clusters such as rho Ophiuchi or
Chamaeleon. The mid-IR fluxes of the Class I and flat-spectrum sources are
found to be on the average larger than those of Class II sources. Stellar
luminosities are estimated for the Class II sample, and its luminosity function
is compatible with a coeval population of about 2 Myr which follows a three
segment power-law IMF. For this age about 20% of the Class IIs are found to be
young brown dwarf candidates. The YSOs are in general strongly clustered, the
Class I sources more than the Class II sources, and there is an indication of
sub-clustering. The sub-clustering of the protostar candidates has a spatial
scale of 0.12 pc. These sub-clusters are found along the NW-SE oriented ridge
and in very good agreement with the location of dense cores traced by
millimeter data. The smallest clustering scale for the Class II sources is
about 0.25 pc, similar to what was found for rho Ophiuchi. Our data show
evidence that star formation in Serpens has proceeded in several phases, and
that a ``microburst'' of star formation has taken place very recently, probably
within the last 10^5 yrs.


title: Jet/environment interactions of FR-I and FR-II radio galaxies

abstract:
  We present the results of new XMM observations of FR-I and FR-II radio
galaxies that show the importance of jet/environment interactions for both
radio-source structure and the properties of the surrounding gas. The FR-I
observations reveal that the distribution of hot gas determines the radio-lobe
morphology, and provide evidence that the subsonic expansion of the lobes heats
the surrounding gas. The FR-II observations show that the sources are at
equipartition and in pressure balance with their surroundings. Finally, we
present an analysis of a sample of elliptical-dominated groups, showing that
radio-source heating is common.


title: Cosmological perturbations through a simple bounce

abstract:
  We present a detailed study of a simple scalar field model that yields
non-singular cosmological solutions. We study both the qualitative dynamics of
the homogeneous and isotropic background and the evolution of inhomogeneous
linear perturbations. We calculate the spectrum of perturbations generated on
super-Hubble scales during the collapse phase from initial vacuum fluctuations
on small scales and then evolve these numerically through the bounce. We show
there is a gauge in which perturbations remain well-defined and small
throughout the bounce, even though perturbations in other commonly used gauges
become large or ill-defined. We show that the comoving curvature perturbation
calculated during the collapse phase provides a good estimate of the resulting
large scale adiabatic perturbation in the expanding phase while the Bardeen
metric potential is dominated by what becomes a decaying mode after the bounce.
We show that a power-law collapse phase with scale factor proportional to
$(-t)^{2/3}$ can yield a scale-invariant spectrum of adiabatic scalar
perturbations in the expanding phase, but the amplitude of tensor perturbations
places important constraints on the allowed initial conditions.


title: The sky behind our galaxy as seen by IBIS on INTEGRAL

abstract:
  During the Core Programme, INTEGRAL has surveyed a large portion of the sky
(around 9000 square degrees); although INTEGRAL is not optimized for
extra-galactic studies its observations have nevertheless given us the
opportunity to explore the sky behind our Galaxy, something which is impossible
in some wavebands due to the presence of strong absorption. Preliminary results
from this exploration are presented and compared with the pre-launch
expectations. In particular, we detail all extragalactic detections obtained so
far: 10 active galaxies and one cluster of galaxies. Of these sources, many
have previously been studied at energies above 10-20 keV while a few are new
hard X-ray discoveries. Since the number of detections is smaller than
estimated on the basis of the IBIS/ISGRI sensitivity, it is likely that some of
the new ISGRI sources found in this survey are extragalactic objects; a few of
these are likely to be AGN and are described in detail.


title: Radiative transfer models of non-spherical prestellar cores

abstract:
  We present 2D Monte Carlo radiative transfer simulations of prestellar cores.
We consider two types of asymmetry: disk-like asymmetry, in which the core is
denser towards the equatorial plane than towards the poles; and axial
asymmetry, in which the core is denser towards the south pole than the north
pole. We limit our treatment to cores with mild asymmetries, which are exposed
directly to the interstellar radiation field or are embedded inside molecular
clouds.
  The isophotal maps of a core depend strongly on the viewing angle. Maps at
wavelengths longer than the peak of the SED (e.g. 850 micron) essentially trace
the column-density. Thus, for instance, cores with disk-like asymmetry appear
elongated when mapped at 850 micron from close to the equatorial plane.
However, at wavelengths near the peak of the SED (e.g. 200 micron), the
emissivity is more strongly dependent on the temperature, and therefore, at
particular viewing angles, there are characteristic features which reflect a
more complicated convolution of the density and temperature fields within the
core.
  These characteristic features are on scales 1/5 to 1/3 of the overall core
size, and so high resolution observations are needed to observe them. They are
also weaker if the core is embedded in a molecular cloud (because the range of
temperature within the core is then smaller), and so high sensitivity is needed
to detect them. Herschel, to be launched in 2007, will in principle provide the
necessary resolution and sensitivity at 170 to 250 micron.


title: XMM-Newton observations of seven soft X-ray excess QSOs

abstract:
  XMM-Newton observations of seven QSOs are presented and the EPIC spectra
analysed. Five of the AGN show evidence for Fe K-alpha emission, with three
being slightly better fitted by lines of finite width; at the 99 per cent level
they are consistent with being intrinsically narrow, though. The broad-band
spectra can be well modelled by a combination of different temperature
blackbodies with a power-law, with temperatures between kT ~ 100-300 eV. On the
whole, these temperatures are too high to be direct thermal emission from the
accretion disc, so a Comptonization model was used as a more physical
parametrization. The Comptonizing electron population forms the soft excess
emission, with an electron temperature of ~ 120-680 eV. Power-law, thermal
plasma and disc blackbody models were also fitted to the soft X-ray excess. Of
the sample, four of the AGN are radio-quiet and three radio-loud. The
radio-quiet QSOs may have slightly stronger soft excesses, although the
electron temperatures cover the same range for both groups.


title:
Simulating galaxy Clusters -II: global star formation histories and
  galaxy populations

abstract:
  Cosmological (LambdaCDM) TreeSPH simulations of the formation and evolution
of galaxy groups and clusters have been performed. The simulations invoke star
formation, chemical evolution with non-instantaneous recycling, metal dependent
radiative cooling, strong star burst and (optionally) AGN driven galactic super
winds, effects of a meta-galactic UV field and thermal conduction. The
properties of the galaxy populations in two clusters, one Virgo-like (T~3 keV)
and one (sub) Coma-like (T~6 keV), are discussed. The global star formation
rates of the cluster galaxies are found to decrease very significantly with
time from redshift z=2 to 0, in agreement with observations. The total K-band
luminosity of the cluster galaxies correlates tightly with total cluster mass,
and for models without additional AGN feedback, the zero point of the relation
matches the observed one fairly well. The match to observed galaxy luminosity
functions is reasonable, except for a deficiency of bright galaxies (M_B <
-20), which becomes increasingly significant with super-wind strength. Results
of a high resolution test indicate that this deficiency is not due to
``over--merging''. The redshift evolution of the luminosity functions from z=1
to 0 is mainly driven by luminosity evolution, but also by merging of bright
galaxies with the cD. The colour--magnitude relation of the cluster galaxies
matches the observed "red sequence" very well and, on average, galaxy
metallicity increases with luminosity. As the brighter galaxies are essentially
coeval, the colour--magnitude relation results from metallicity rather than age
effects, as observed.


title: Large- and Small-Scale Feedback in the Starburst Canters of Galaxies

abstract:
  The interplay between stellar populations and gas in local starburst galaxies
is analyzed using images from the Hubble Space Telescope to map the ages of the
young stellar components and to isolate the contribution of shocks on spatial
scales ranging from a few tens of pc to ~1 kpc. The shocked gas represents a
small fraction of the total ionized gas in these objects, yet it can have
profound effects on the long-term evolution of the starburst, which may include
the triggering of new star formation.


title:
Exploring the Upper Red Giant and Asymptotic Giant Branches: the
  Globular Cluster M5

abstract:
  We have tabulated lists of upper red giant, horizontal, and asymptotic giant
branch (RGB, HB, AGB) stars in the globular cluster M5 that are complete to
over 10' from the core for the RGB and AGB samples, and 8' for the HB sample.
The large samples give us the most precise value of R_2 = N_AGB / N_HB to date
for a single globular cluster (0.176 +/- 0.018). This is incompatible with
theoretical calculations using the most recent physical inputs. The discrepancy
can probably be attributed to the dependence of observed R_2 values on
horizontal branch morphology. We identify the cluster M55 as being another
possible example of this effect. Samples of HB and AGB stars in populous
clusters may provide a means of calibrating the masses of horizontal branch
stars in globular clusters. The cumulative luminosity function of the upper red
giant branch shows an apparent deficit of observed stars near the tip of the
branch. This feature has less than a 2% chance of being due to statistical
fluctuations. The slope of the cumulative luminosity function for AGB stars is
consistent with the theoretically predicted value from stellar models when
measurement bias is taken into account. We also introduce a new diagnostic
R_clump that reflects the fraction of the AGB lifetime that a star spends in
the AGB clump. For M5, we find R_clump = 0.42 +/- 0.05, in marginal
disagreement with theoretical predictions. Finally, we note that the blue half
of M5's instability strip (where first overtone RR Lyraes reside) is
underpopulated, based on the large numbers of fundamental mode RR Lyraes and on
the nonvariable stars at the blue end of the instability strip. This fact may
imply that the evolutionary tracks (and particularly the colors) of stars in
the instability strip are affected by pulsations.


title: A Distant Extended Spiral Arm in the Fourth Quadrant of the Milky Way

abstract:
  Using data from the Southern Galactic Plane Survey we present a possible
distant spiral arm in the fourth quadrant of the Milky Way. The very distinct
and cohesive feature can be traced for over 70 deg as the most extreme positive
velocity feature in the longitude-velocity diagram. The feature is at a
Galactic radius between 18 and 24 kpc and appears to be the last major
structure before the end of the HI disk. We compare the feature with a Galactic
spiral model and show that it is well reproduced by a spiral arm of pitch
angle, i ~ 9 deg. The arm is quite well confined to the Galactic plane,
dropping at most 1 kpc below the Galactic equator. Over most of its length the
arm is 1 - 2 kpc thick.


title: Thermonuclear burst physics with RXTE

abstract:
  Recently we have made measurements of thermonuclear burst energetics and
recurrence times which are unprecedented in their precision, largely thanks to
the sensitivity of the Rossi X-ray Timing Explorer. In the "Clocked Burster",
GS 1826-24, hydrogen burns during the burst via the rapid-proton (rp) process,
which has received particular attention in recent years through theoretical and
modelling studies. The burst energies and the measured variation of alpha (the
ratio of persistent to burst flux) with accretion rate strongly suggests solar
metallicity in the neutron star atmosphere, although this is not consistent
with the corresponding variation of the recurrence time. Possible explanations
include extra heating between the bursts, or a change in the fraction of the
neutron star over which accretion takes place. I also present results from 4U
1746-37, which exhibits regular burst trains which are interrupted by "out of
phase" bursts.


title:
The nature of the Galactic Center source IRS 13 revealed by high spatial
  resolution in the infrared

abstract:
  High spatial resolution observations in the 1 to 3.5 micron region of the
Galactic Center source known historically as IRS 13 are presented. They include
ground-based adaptive optics images in the H, Kp (2.12/0.4 micron) and L bands,
NICMOS data in filters between 1.1 and 2.2 micron, and integral field
spectroscopic data from BEAR, an Imaging FTS, in the HeI 2.06 micron and the
Br$\gamma$ line regions. Analysis of all these data provides a completely new
picture of the main component, IRS 13E, which appears as a cluster of seven
individual stars within a projected diameter of ~0.5'' (0.02 pc). The brightest
sources, 13E1, 13E2, 13E3 (a binary), and 13E4, are all massive stars, 13E1 a
blue object, with no detected emission line while 13E2 and 13E4 are high-mass
emission line stars. 13E2 is at the WR stage and 13E4 a massive O-type star.
13E3A and B are extremely red objects, proposed as other examples of dusty WR
stars. All these sources have a common westward proper motion. 13E5, is a red
source similar to 13E3A/B. This concentration of comoving massive hot stars,
IRS 13E, is proposed as the remaining core of a massive star cluster, which
could harbor an intermediate-mass black hole (IMBH) of ~1300 M_sol. This
detection plays in favor of a scenario in which the helium stars and the other
hot stars in the central pc originate from the stripping of a massive cluster
formed several tens of pc from the center. The detection of a discrete X-ray
emission (Baganoff et al. 2003) at the IRS~13 position is examined in this
context.


title: Interstellar Turbulence I: Observations and Processes

abstract:
  This two-part review summarizes interstellar turbulence and its implications.
The first part begins with diagnostics and energy sources. Turbulence theory is
considered in detail, including the basic fluid equations, solenoidal and
compressible modes, global inviscid quadratic invariants, scaling arguments,
energy transfer and cascade, velocity probability distributions, and turbulent
pressure. Theories of magnetohydrodynamic turbulence, including collisionless
MHD turbulence, are discussed, emphasizing various proposals for energy
spectra. A large variety of numerical simulations of interstellar turbulence
are reviewed. Models have reproduced many of the basic features of the observed
scaling relations, predicted fast decay rates for supersonic MHD turbulence,
and derived probability distribution functions for density. Thermal
instabilities and thermal phases have a new interpretation in a turbulent
medium. Large-scale models with various combinations of self-gravity, magnetic
fields, supernovae, and star formation are beginning to resemble the observed
interstellar medium in morphology and statistical properties. The role of
self-gravity in turbulent gas is clarified, leading to new paradigms for the
formation of star clusters, the stellar mass function, the origin of stellar
rotation and binary stars, and the effects of magnetic fields.


title: Interstellar Turbulence II: Implications and Effects

abstract:
  Interstellar turbulence has implications for the dispersal and mixing of the
elements, cloud chemistry, cosmic ray scattering, and radio wave propagation
through the ionized medium. This review discusses the observations and theory
of these effects. Metallicity fluctuations are summarized, and the theory of
turbulent transport of passive tracers is reviewed. Modeling methods, turbulent
concentration of dust grains, and the turbulent washout of radial abundance
gradients are discussed. Interstellar chemistry is affected by turbulent
transport of various species between environments with different physical
properties and by turbulent heating in shocks, vortical dissipation regions,
and local regions of enhanced ambipolar diffusion. Cosmic rays are scattered
and accelerated in turbulent magnetic waves and shocks, and they generate
turbulence on the scale of their gyroradii. Radio wave scintillation is an
important diagnostic for small scale turbulence in the ionized medium, giving
information about the power spectrum and amplitude of fluctuations. The theory
of diffraction and refraction is reviewed, as are the main observations and
scintillation regions.


title:
The Burst and Transient Source Experiment (BATSE) Earth Occultation
  Catalog of Low-Energy Gamma-Ray Sources

abstract:
  The Burst and Transient Source Experiment (BATSE), aboard the Compton Gamma
Ray Observatory (CGRO), provided a record of the low-energy gamma-ray sky
(20-1000 keV) between 1991 April and 2000 May (9.1y). Using the Earth
Occultation Technique to extract flux information, a catalog of sources using
data from the BATSE large area detectors has been prepared. The first part of
the catalog consists of results from the monitoring of 58 sources, mostly
Galactic. For these sources, we have included tables of flux and spectral data,
and outburst times for transients. Light curves (or flux histories) have been
placed on the world wide web. We then performed a deep-sampling of 179 objects
(including the aforementioned 58 objects) combining data from the entire 9.1y
BATSE dataset. Source types considered were primarily accreting binaries, but a
small number of representative active galaxies, X-ray-emitting stars, and
supernova remnants were also included. The deep sample results include definite
detections of 83 objects and possible detections of 36 additional objects. The
definite detections spanned three classes of sources: accreting black hole and
neutron star binaries, active galaxies and supernova remnants. Flux data for
the deep sample are presented in four energy bands: 20-40, 40-70, 70-160, and
160-430 keV. The limiting average flux level (9.1 y) for the sample varies from
3.5 to 20 mCrab (5 sigma) between 20 and 430 keV, depending on systematic
error, which in turn is primarily dependent on the sky location. To strengthen
the credibility of detection of weaker sources (5-25 mCrab), we generated Earth
occultation images, searched for periodic behavior using FFT and epoch folding
methods, and critically evaluated the energy-dependent emission in the four
flux bands.


title:
The Thermal Regulation of Gravitational Instabilities in Disks Around
  Young Stars

abstract:
  Gravitational instabilities (GIs) are spiral distortions in a
self-gravitating disk that appear wherever the local surface density and
temperature become favorable for their growth. The restructuring of the disk as
it becomes unstable, the thermal processes that sustain the instabilities, and
their effect on the long-term evolution of the disk are the studied using 3-D
hydrodynamic simulations. These show that the cooling and heating processes
balance each other, and as a result the disk asymptotes to quasi-equilibrium
within a few orbital periods after the GI onset. The final values of the
internal energy and the Toomre Q are independent of cooling time, while the
asymptotic mass transport rates are inversely proportional to the cooling time.
The formation of dense rings is common in these simulations. GIs fragment into
clumps when the cooling time is on the order of the local orbital time, but the
clumps are short-lived. External radiation can affect the evolution
considerably. GIs are an effective angular momentum and mass transport
mechanism, and during their onset, they can reproduce the mass transport rates
necessary to trigger FU Ori outbursts.


title:
The Impact of Distance Uncertainties on Local Luminosity and Mass
  Functions

abstract:
  In order to investigate discrepancies between recent published estimates of
the the HI mass function (HIMF), we explore the impact of distance
uncertainties on the derivation of the faint end slope of mass and luminosity
functions of galaxies in the local volume by deriving HIMFs from mock HI
surveys. We consider various survey geometries and depths and compare the HIMFs
measured when using ``real'' distances, distances derived by assuming pure
Hubble flow and distances assigned from parametric models of the local velocity
field. The effect is variable and dependent on the exact survey geometry, but
can easily lead to incorrect estimates of the HIMF, particularly at the low
mass end. We show that at least part of the discrepancies among recent
derivations of the HIMF can be accounted for by the use of different methods to
assign distances. We conclude that a better understanding of the local velocity
field will be necessary for accurate determinations of the local galaxy
luminosity and mass functions.


title: Discovery of a candidate inner Oort cloud planetoid

abstract:
  We report the discovery of the minor planet 2003 VB12 (popularly named
Sedna), the most distant object ever seen in the solar system. Pre-discovery
images from 2001, 2002, and 2003 have allowed us to refine the orbit
sufficiently to conclude that 2003 VB12 is on a highly eccentric orbit which
permanently resides well beyond the Kuiper belt with a semimajor axis of
480$\pm$40 AU and a perihelion of 76$\pm$4AU. Such an orbit is unexpected in
our current understanding of the solar system, but could be the result of
scattering by a yet-to-be-discovered planet, perturbation by an anomalously
close stellar encounter, or formation of the solar system within a cluster of
stars. In all of these cases a significant additional population is likely
present, and in the two most likely cases 2003 VB12 is best considered a member
of the inner Oort cloud, which then extends to much smaller semimajor axes than
previously expected. Continued discovery and orbital characterization of
objects in this inner Oort cloud will verify the genesis of this unexpected
population.


title:
A New calculation of the atmospheric neutrino flux in a 3-dimensional
  scheme

abstract:
  We have revised the calculation of the flux of atmospheric neutrinos based on
a 3-dimensional scheme with the realistic IGRF geomagnetic model. The primary
flux model has been revised, based on the AMS and BESS observations, and the
interaction model updated to DPMJET-III. With a fast simulation code and
computer system, the statistical errors in the Monte Carlo study are
negligible. We estimate the total uncertainty of the atmospheric neutrino flux
prediction is reduced to $\lesssim$ 10 % below 10 GeV. The `3-dimensional
effects' are found to be almost the same as the study with the dipole magnetic
field, but the muon curvature effect remains up to a few 10 GeV for horizontal
directions. The uncertainty of the absolute normalization of the atmospheric
neutrino is still large above 10 GeV due to the uncertainty of the primary
cosmic ray flux above 100 GeV. However, the zenith angle variation is not
affected by these uncertainties.


title:
Search for Calibrators for the Submillimeter Array: I. High-Mass Star
  Forming Regions

abstract:
  We present initial results of an ongoing search for interferometric
calibrators at submillimeter (sub-mm) wavelengths with the Submillimeter Array
(SMA). Powerful radio galaxies are commonly used as calibrators at centimeter
and millimeter wavelengths, but many are not strong enough to serve as
calibrators at sub-mm wavelengths because of their rapidly declining flux
densities toward shorter wavelengths. The inability to find a calibrator close
to the target source may limit or even prevent us from imaging many interesting
sources at sub-mm wavelengths. Here, we investigate whether high-mass
protostellar objects and ultracompact HII regions can serve as useful
calibrators for the SMA. The dust emission associated with these objects makes
them among the brightest sub-mm sources in the sky. Our observations at 0.85 mm
(345 GHz) with an angular resolution of ~3" reveal that although a large
fraction of the dust emission originates from an extended ``halo'' component, a
compact unresolved component often remains that when sufficiently strong may
serve as a useful calibrator. These observations also provide a first glimpse
at the small-scale distribution of dust around ultracompact HII regions and
high-mass protostellar objects at sub-mm wavelengths. We discuss the origin of
the core-halo structure seen in many sources, and conclude with suggestions for
future searches for calibrators with the SMA.


title: FUSE Observations of the Symbiotic Star AG Draconis

abstract:
  Spectra of the bright symbiotic star AG Draconis (BD+67D922) in the
wavelength range 905-1187 A obtained with the Far Ultraviolet Spectroscopic
Explorer (FUSE) are presented. The spectra show a number of narrow, nebular
emission lines, together with a uniform continuum from the hot component of the
system, and numerous interstellar absorption lines. We infer the existence of
Ne VIII in the AG Dra nebula through the identification of the Ne VII 973.3 A
recombination line. The emission line spectrum is dominated by intense lines of
O VI, but also shows weaker lines from highly-ionized ions including Ne V, Ne
VI, S IV, S VI. Members of the He II Balmer series can be identified up to
n=20. Lines of Fe II and Fe III fluoresced by O VI 1032 are identified at
wavelengths 1141.172 A and 1142.429 A, respectively. The emission lines are
shown to be produced in a plasma with an electron temperature of 20-30,000 K,
photoionized by the white dwarf. The Ne VI 997/999 ratio shows that this ion
and all others except perhaps Ne VII are formed at least 300 white dwarf radii
from the white dwarf. Revised wavelengths for the Ne V 2s^2 2p^2 ^3P_0,1 - 2s
2p^3 ^5S_2 and Ne VI 2s^2 2p ^2P_J - 2s 2p^2 ^4P_J' transitions are published.


title: Broadband X-ray spectrum of XTE J1550-564 during 2003 outburst

abstract:
  Results of broadband INTEGRAL and RXTE observations of the Galactic
microquasar XTE J1550-564 during outburst in spring 2003 are presented. During
the outburst the source was found in a canonical low/hard spectral state.


title:
Simultaneous X-ray and Ultraviolet spectroscopy of the Seyfert galaxy
  NGC 5548. III. X-ray time variability

abstract:
  The Seyfert 1 galaxy NGC 5548 was observed for a week by Chandra using both
the HETGS and LETGS spectrometers. In this paper we study the time variability
of the continuum radiation. During our observation, the source showed a gradual
increase in flux over four days, followed by a rapid decrease and flattening of
the light curve afterwards. Superimposed upon these relatively slow variations
several short duration bursts or quasi-periodic oscillations occured with a
typical duration of several hours and separation between 0.6-0.9 days. The
bursts show a delay of the hard X-rays with respect to the soft X-rays of a few
hours. We interprete these bursts as due to a rotating, fluctuating hot spot at
approximately 10 gravitational radii; the time delay of the hard X-rays from
the bursts agree with the canonical picture of Inverse Compton scattering of
the soft accretion disk photons on a hot medium that is relatively close to the
central black hole.


title:
Star-forming galaxies at z ~ 2: a major science case for the EMIR/GOYA
  survey on GTC

abstract:
  We present the first results of a project aiming to derive the physical
properties of high-redshift lensed galaxies, intrinsically fainter than the
Lyman break galaxies currently observed in the field. From FORS and ISAAC
spectroscopy on the VLT, we use the full rest-frame UV-to-optical range to
derive the physical properties (SFR, extinction, chemical abundances, dynamics,
mass, etc) of low-luminosity z ~ 2 star-forming galaxies. Although the sample
is still too small for statistical studies, these results give an insight into
the nature and evolutionary status of distant star-forming objects and their
link with present-day galaxies. Such a project will serve as a basis for the
scientific analysis of the EMIR/GOYA survey on the GTC.


title: Jeans criterion in nonextensive statistical mechanics

abstract:
  The Jeans gravitational instability in nonextensive statistical mechanics is
studied and a general form of the generalized Jeans criterion is obtained that
is related to the q-function . In this approach, the nonextensive model of
classical ideal gas is applied to the Jeans problem instead of the ordinary one
in extensive statistical mechanics and the generalized critical wavelength to
describe the gravitational instability is deduced. This nonextensive
modification of the Jeans criterion leads to a new critical length that depends
not only on the nonextensive parameter q but also on the dimension D and the
total particle numbers N of the system. When, the Jeans length is perfectly
recovered. We also give the nonextensive parameter q a physical interpretation
that represents an isothermal process of the gas, corresponding to the state of
complete mixing, but 0< q <1 is nonisothermal, corresponding to the state of
incomplete mixing, it measures the degree of mixing.


title:
Jeans criterion and nonextensive velocity distribution function in
  kinetic theory

abstract:
  The effect of nonextensivity of self-gravitating systems on the Jeans
criterion for gravitational instability is studied in the framework of Tsallis
statistics. The nonextensivity is introduced in the Jeans problem by a
generalized q-nonextensive velocity distribution function through the equation
of state of ideal gas in nonextensive kinetic theory. A new Jeans criterion is
deduced with a factor that, however, differs from that one in Ref.[21] and new
results of gravitational instability are analyzed for the nonextensive
parameter q. An understanding of physical meaning of q and a possible seismic
observation to find astronomical evidence for a value of q different from unity
are also discussed.


title:
Observational evidence for a connection between SMBHs and dark matter
  haloes

abstract:
  We investigate the relation between circular velocity vc and bulge velocity
dispersion sigma in spiral galaxies, based on literature data and new
spectroscopic observations. We find a strong, nearly linear vc-sigma
correlation with a negligible intrinsic scatter, and a striking agreement with
the corresponding relation for elliptical galaxies. The least massive galaxies
(sigma < 80 km/s) significantly deviate from this relation. We combine this
vc-sigma correlation with the well-known MBH-sigma relation to obtain a tight
correlation between circular velocity and supermassive black hole mass, and
interpret this as observational evidence for a close link between supermassive
black holes and the dark matter haloes in which they presumably formed. Apart
from being an important ingredient for theoretical models of galaxy formation
and evolution, the relation between MBH and circular velocity has the potential
to become an important practical tool in estimating supermassive black hole
masses in spiral galaxies.


title: The Stellar Populations of Low-redshift Clusters

abstract:
  We present some preliminary results from an on-going study of the evolution
of stellar populations in rich clusters of galaxies. This sample contains core
line-strength measurements from 183 galaxies with b_J <= 19.5 from four
clusters with <z>~0.04. Using predictions from stellar population models to
compare with our measured line strengths we can derive relative
luminosity-weighted mean ages and metallicities for the stellar populations in
each of our clusters. We also investigate the Mgb'-sigma and Hbeta_G'-sigma
scaling relations. We find that, consistent with previous results, Mgb' is
correlated with sigma, the likely explanation being that larger galaxies are
better at retaining their heavier elements due to their larger potentials.
Hbeta', on the other hand, we find to be anti-correlated with sigma. This
result implies that the stellar populations in larger galaxies are older than
in smaller galaxies.


title: Period and chemical evolution of SC stars

abstract:
  The SC and CS stars are thermal-pulsing AGB stars with C/O ratio close to
unity. Within this small group, the Mira variable BH Cru recently evolved from
spectral type SC (showing ZrO bands) to CS (showing weak C2). Wavelet analysis
shows that the spectral evolution was accompanied by a dramatic period
increase, from 420 to 540 days, indicating an expanding radius. The pulsation
amplitude also increased. Old photographic plates are used to establish that
the period before 1940 was around 490 days. Chemical models indicate that the
spectral changes were caused by a decrease in stellar temperature, related to
the increasing radius. There is no evidence for a change in C/O ratio. The
evolution in BH Cru is unlikely to be related to an on-going thermal pulse.
Periods of the other SC and CS stars, including nine new periods, are
determined. A second SC star, LX Cyg, also shows evidence for a large increase
in period, and one further star shows a period inconsistent with a previous
determination. Mira periods may be intrinsically unstable for C/O ~ 1; possibly
because of a feedback between the molecular opacities, pulsation amplitude, and
period. LRS spectra of 6 SC stars suggest a feature at wavelength > 15 micron,
which resembles one recently attributed to the iron-sulfide troilite. Chemical
models predict a large abundance of FeS in SC stars, in agreement with the
proposed association.


title: No evidence for Dark Energy Metamorphosis ?

abstract:
  Recent attempts to fit Type Ia supernova data by modeling the dark energy
density as a truncated Taylor series have suggested the possibility of
metamorphosis, i.e., a rapidly evolving equation of state parameter, w_DE(z).
However, we show that fits using that parametrization have significant
problems: evolution of w_DE(z) is both favoured and in some sense forced, and
the equation of state parameter blows up or diverges in large regions of the
parameter space. To further elucidate these problems we have simulated sets of
supernova data in a Lambda-universe to show that the suggested ``evidence'' for
metamorphosis is also common for w_DE=-1.


title:
A Search for H-alpha Absorption in the Exosphere of the Transiting
  Extrasolar Planet HD 209458b

abstract:
  There is evidence that the transiting planet HD 209458b has a large exosphere
of neutral hydrogen, based on a 15% decrement in Lyman-alpha flux that was
observed by Vidal-Madjar et al. during transits. Here we report upper limits on
H-alpha absorption by the exosphere. The results are based on optical spectra
of the parent star obtained with the Subaru High Dispersion Spectrograph.
Comparison of the spectra taken inside and outside of transit reveals no
exospheric H-alpha signal greater than 0.1% within a 5.1A band (chosen to have
the same Delta_lambda/lambda as the 15% Ly-alpha absorption). The corresponding
limit on the column density of n=2 neutral hydrogen is N_2 <~ 10^9 cm^{-2}.
This limit constrains proposed models involving a hot (~10^4 K) and
hydrodynamically escaping exosphere.


title: A Detection of the Integrated Sachs-Wolfe Effect

abstract:
  We have detected statistically significant correlations between the cosmic
microwave background and two tracers of large-scale structure, the HEAO1 A2
full sky hard X-ray map and the NVSS 1.4 GHz, nearly full sky radio galaxy
survey. The level of correlations in these maps is consistent with that
predicted for the integrated Sachs-Wolfe (ISW) effect in the context of a
Lambda CDM cosmological model and, therefore, provides independent evidence for
a cosmological constant. A maximum likelihood fit to the amplitude of the ISW
effect relative to the predicted value is 1.13 +- 0.35 (statistical error
only).


title:
Stellar Populations and Kinematics of Red Galaxies at z>2: Implications
  for the Formation of Massive Galaxies

abstract:
  We recently identified a substantial population of galaxies at z>2 with red
rest-frame optical colors. These distant red galaxies (DRGs) are efficiently
selected by the simple observed color criterion J-K>2.3. In this paper we
present NIR spectroscopy with Keck/NIRSPEC of six DRGs at 2.4<z<3.2. We detect
continuum emission and emission lines of all observed galaxies. Equivalent
widths of H alpha are 20-30 Ang, smaller than measured for LBGs and nearby
LIRGs, and comparable to normal nearby galaxies. The modest equivalent widths
imply that the galaxies either have a decreasing star formation rate, or that
they are very dusty. Fitting both the photometry and the H alpha lines, we find
continuum extinction A_V=1-2 mag, ages 1-2.5 Gyr, star formation rates 200-400
solar masses/yr, and stellar masses 1-5x10^11 solar masses for models with
constant star formation rates. From [NII]/H alpha ratios we infer that the
metallicities are high, 1-1.5 x Solar. For four galaxies we can determine line
widths from the optical emission lines. The widths are high, ranging from
130-240 km/s, and by combining data for LBGs and DRGs we find significant
correlations between linewidth and restframe U-V color, and between linewidth
and stellar mass. The latter correlation has a similar slope and offset as the
``baryonic Tully-Fisher relation'' for nearby galaxies. The median dynamical
mass is ~2x10^11 solar masses, supporting the high stellar masses inferred from
the photometry. We find that the median M/L_V ~ 0.8, a factor of ~5 higher than
measured for LBGs. We infer from our small sample that DRGs are dustier, more
metal rich, more massive, and have higher ages than z=3 LBGs of the same
rest-frame V-band luminosity. Their high M/L ratios imply that they contribute
significantly to the stellar mass density at z~2.5. [ABRIDGED]


title:
Photometric Variability Among the Brightest Asymptotic Giant Branch
  Stars Near the Center of M32

abstract:
  Deep K' images with 0.1 arcsec angular resolution, obtained with ALTAIR+NIRI
on Gemini North, are used to investigate photometric variablity among the
brightest asymptotic giant branch (AGB) stars in the central regions of M32.
Based on a comparison with brightnesses obtained from the K-band data discussed
by Davidge et al. (2000, ApJ, 545, L89), it is concluded that (1) at least 60%
of bright AGB stars near the center of M32 are photometrically variable, and
(2) the amplitudes of the light variations are similar to those of long period
variables in the Galactic bulge. We do not find evidence for a population of
large amplitude variables, like those detected by IRAS in the Galactic bulge.
The technique discussed here may prove useful for conducting an initial
reconnaisance of photometric variability among AGB stars in spheroids in the
Virgo cluster and beyond, where the required long exposure times may restrict
observations to only a few epochs.


title:
The nature of a gravitationally lensed sub-millimetre arc in
  MS0451.6-0305: two interacting galaxies at z~2.9?

abstract:
  We present a new SCUBA image of the cluster MS0451.6-0305, which exhibits
strong, extended sub-mm flux at 850 microns. The most striking feature in the
map is an elongated region of bright sub-mm emission, with a flux density of
>10 mJy over several beam-sizes. This region is apparently coincident with a
previously known optical arc (which turns out to be a strongly lensed Lyman
Break Galaxy at z=2.911), as well as with a newly identified multiply-imaged
ERO (Extremely Red Object) pair predicted to be at a similar, if not identical
redshift. By combing a detailed lensing model with deep images from HST,
Chandra, CFHT, JCMT, and spectra from the VLT, we conclude that both the
strongly lensed optical arc and ERO systems have properties consistent with
known sub-mm emitters. Using a simple model for the two sources, we estimate
that the multiply-lensed EROs contribute the majority of the flux in the SCUBA
lensed arc. Correcting for the lensing amplification, we estimate that the
inherent 850 micron fluxes for both objects are ~0.4 mJy. If the LBG and ERO
pair are truly at the same redshift, then they are separated by only ~10 kpc in
the source plane, and hence constitute an interacting system at z~2.9. Higher
angular resolution observations in sub-mm/mm will permit us to more accurately
separate the contribution from each candidate, and better understand the nature
of this system.


title:
Ks-band luminosity function of the z=1.237 cluster of galaxies RDCS
  J1252.9-2927

abstract:
  We derive the Ks-band luminosity function (LF) of the z=1.237 massive X-ray
luminous cluster of galaxies RDCS J1252.9-2927. Photometric redshifts, derived
from deep multi-wavelength BVRIzJKs data, and calibrated using a large subset
of galaxies with spectroscopic redshifts, are used to separate the cluster
galaxy population from the foreground and background field galaxy population.
This allows for a simultaneous determination of the characteristic magnitude
Ks* and faint end slope alpha of the LF without having to make an uncertain
statistical background subtraction. The shape of the bright end of the derived
LF is similar to that measured at similar restframe wavelengths (in the z-band)
in local clusters, but the characteristic magnitude is brighter by Delta
Mz*=-1.40(+0.49/-0.58) magnitudes, suggesting that the massive cluster
ellipticals that dominate the bright end of the LF were already in place at
z=1.237. The derived alpha is shallower (at the 2.2 sigma level) than the value
measured in the z-band in clusters in the local universe, suggesting that RDCS
J1252.9-2927 contains a relatively smaller fraction of low mass galaxies than
clusters in the local universe. The results presented in this paper are a
challenge for semi analytical hierarchical models of galaxy formation which
predict the characteristic magnitude to grow fainter and the faint end slope to
steepen with redshift as the massive galaxies break up into their progenitors.
The observed evolution is consistent with a scenario in which clusters are
composed of a population of massive galaxies which formed at high redshift
(z>>1) and subsequently evolved passively, and a population of lower mass
galaxies which are gradually accreted from the field, primarily at lower
redshift (z<1). (Abridged)


title: Why (inner) bars are important but not sufficient

abstract:
  I briefly report on the work conducted to probe the gravitational potential
of active and non-active disk galaxies using two-dimensional gas and stellar
kinematics, first emphasizing the need to make a distinction between ''fuelling
the nucleus'' and ''building a gas reservoir''.


title: Three-Point Statistics from a New Perspective

abstract:
  Multipole expansion of spatial three-point statistics is introduced as a tool
for investigating and displaying configuration dependence. The novel
parametrization renders the relation between bi-spectrum and three-point
correlation function especially transparent as a set of two-dimensional Hankel
transforms. It is expected on theoretical grounds, that three-point statistics
can be described accurately with only a few multipoles. In particular, we show
that in the weakly non-linear regime, the multipoles of the reduced bispectrum,
$Q_l$, are significant only up to quadrupole. Moreover, the non-linear bias in
the weakly non-linear regime only affects the monopole order of these
statistics. As a consequence, a simple, novel set of estimators can be
constructed to constrain galaxy bias. In addition, the quadrupole to dipole
ratio is independent of the bias, thus it becomes a novel diagnostic of the
underlying theoretical assumptions: weakly non-linear gravity and perturbative
local bias. To illustrate the use of our approach, we present predictions based
on both power law, and CDM models. We show that the presently favoured
SDSS-WMAP concordance model displays strong ``baryon bumps'' in the $Q_l$'s.
Finally, we sketch out three practical techniques estimate these novel
quantities: they amount to new, and for the first time edge corrected,
estimators for the bispectrum.


title: Wide Angle Redshift Distortions Revisited

abstract:
  We explore linear redshift distortions in wide angle surveys from the point
of view of symmetries. We show that the redshift space two-point correlation
function can be expanded into tripolar spherical harmonics of zero total
angular momentum $S_{l_1 l_2 l_3}(\hat x_1, \hat x_2, \hat x)$. The
coefficients of the expansion $B_{l_1 l_2 l_3}$ are analogous to the $C_l$'s of
the angular power spectrum, and express the anisotropy of the redshift space
correlation function. Moreover, only a handful of $B_{l_1 l_2 l_3}$ are
non-zero: the resulting formulae reveal a hidden simplicity comparable to
distant observer limit. The $B_{l_1 l_2 l_3}$ depend on spherical Bessel
moments of the power spectrum and $f = \Omega^{0.6}/b$. In the plane parallel
limit, the results of \cite{Kaiser1987} and \cite{Hamilton1993} are recovered.
The general formalism is used to derive useful new expressions. We present a
particularly simple trigonometric polynomial expansion, which is arguably the
most compact expression of wide angle redshift distortions. These formulae are
suitable to inversion due to the orthogonality of the basis functions. An
alternative Legendre polynomial expansion was obtained as well. This can be
shown to be equivalent to the results of \cite{SzalayEtal1998}. The simplicity
of the underlying theory will admit similar calculations for higher order
statistics as well.


title: Highly ionized Fe K emission lines from the LINER galaxy M 81

abstract:
  We present spectral and timing results from a long (130 ks) XMM-NEWTON EPIC
observation of the nucleus of the Seyfert/LINER galaxy M 81. During the
observation the X-ray flux varied by 20%, but there was no significant change
in spectral shape. The 2-10 keV spectrum is well described by a power law
continuum and three narrow Fe K emission lines at 6.4, 6.7 and 6.96 keV. The
three emission lines have equivalent widths of 39, 47, and 37 eV respectively.
The ratios of the three lines are thus more similar to those observed from the
Galactic Centre region than to those typically observed from Seyfert galaxies.
The high ionization lines most likely originate either from photoionized gas
within 0.1 pc of the nucleus of M 81, or from a non-thermal distribution of
cosmic-ray electrons interacting with the 0.2-0.6 keV thermal plasma which is
found in the bulge of M 81.


title: Coordinated INTEGRAL and optical observations of SS433

abstract:
  Results of simultaneous {\it INTEGRAL} and optical observations of galactic
microquasar SS433 in May 2003 are presented. The analysis of the X-ray and
optical eclipse duration and hard X-ray spectra obtained by {\it INTEGRAL}
together with optical spectroscopy obtained on the 6-m telescope allows us to
construct a model of SS433 as a massive X-ray binary. X-ray eclipse in hard
X-rays has a depth of $\sim 80%$ and extended wings. The optical spectroscopy
allows us to identify the optical companion as a A5-A7 supergiant and to
measure its radial velocity semi-amplitude $K_v=132$ km/s. A strong heating
effect in the optical star atmosphere is discovered spectroscopically. The
observed broadband X-ray spectrum 2-100 keV can be described by emission from
optically thin thermal plasma with $kT\sim 15-20 keV$


title: The Cyclic Model Simplified

abstract:
  The Cyclic Model attempts to resolve the homogeneity, isotropy, and flatness
problems and generate a nearly scale-invariant spectrum of fluctuations during
a period of slow contraction that precedes a bounce to an expanding phase. Here
we describe at a conceptual level the recent developments that have greatly
simplified our understanding of the contraction phase and the Cyclic Model
overall. The answers to many past questions and criticisms are now understood.
In particular, we show that the contraction phase has equation of state w>1 and
that contraction with w>1 has a surprisingly similar properties to inflation
with w < -1/3. At one stroke, this shows how the model is different from
inflation and why it may work just as well as inflation in resolving
cosmological problems.


title: Newcomers Meet the Intracluster Medium in the Coma Cluster

abstract:
  A main topic at this meeting is how galaxies are affected when they enter for
the first time the cluster environment from the outskirts. Most of the times we
are forced to infer the environmental effects indirectly, relying on systematic
variations of galaxy properties with environment, but there aren't many
examples of direct observations able to unveil ongoing transformations taking
place, and the corresponding mechanism producing it. We present a case in which
it is possible to identify the cluster environment, and in particular the
intracluster medium and the recent infall history of galaxies onto the cluster,
as the cause for a recent, abrupt change in the evolutionary history of
galaxies.


title: Analogous Hawking Radiation from Astrophysical Black Hole Accretion

abstract:
  For the first time in literature, we provide an exact analytical scheme for
calculating the analogous Hawking temperature and surface gravity for general
relativistic accretion onto astrophysical black holes. Our calculation may
bridge the gap between the theory of transonic astrophysical accretion and the
theory of analogous Hawking radiation, and may allow one to compare the
properties of the two types of horizons, electromagnetic and acoustic, in
connection to the black hole physics. We show that the domination of the
analogous Hawking radiation over the actual Hawking radiation may be a real
astrophysical phenomena. We also discuss the possibilities of the emergence of
analogous white holes around astrophysical black holes. Our calculation is
general enough to accommodate accreting black holes with any mass.


title: Pulsar kicks and dark matter from a sterile neutrino

abstract:
  The observed velocities of radio pulsars, which range in the hundreds
kilometers per second, and many of which exceed 1000 km/s, are not explained by
the standard physics of the supernova explosion. However, if a sterile neutrino
with mass in the 1-20 keV range exists, it would be emitted asymmetrically from
a cooling neutron star, which could give it a sufficient recoil to explain the
pulsar motions. The same particle can be the cosmological dark mater. Future
observations of X-ray telescopes and gravitational wave detectors can confirm
or rule out this explanation.


title: Dark Energy Search with Supernovae

abstract:
  To determine the nature of dark energy from observational data, it is
important that we use model-independent and optimal methods. We should probe
dark energy using its density (allowed to be a free function of cosmic time)
instead of its equation of state. We should minimize gravitational lensing
effect on supernovae by flux-averaging. We need to include complementary data
(for example, from the Cosmic Microwave Background [CMB] and large scale
structure [LSS]) in a consistent manner to help break the degeneracy between
the dark energy density and the matter density fraction. We should push for
ambitious future supernova surveys that can observe a large number of
supernovae at the highest possible redshifts. I discuss these and other issues
that will be important in our quest to unravel the mystery of the nature of
dark energy.
  Current supernova, CMB, and LSS data already rule out dark energy models with
dark energy densities that vary greatly with time; with the cosmological
constant model providing an excellent fit to the data. A precise measurement of
dark energy density as a free function of cosmic time will have a fundamental
impact on particle physics and cosmology.


title:
Hierarchical Formation of Galaxies with Dynamical Response to
  Supernova-Induced Gas removal

abstract:
  We reanalyze the formation and evolution of galaxies in the hierarchical
clustering scenario. Using a semi-analytic model (SAM) of galaxy formation
described in this paper, which we hereafter call the Mitaka model, we
extensively investigate the observed scaling relations of galaxies among
photometric, kinematic, structural and chemical characteristics. In such a
scenario, spheroidal galaxies are assumed to be formed by major merger and
subsequent starburst, in contrast to the traditional scenario of monolithic
cloud collapse. As a new ingredient of SAMs, we introduce the effects of
dynamical response to supernova-induced gas removal on size and velocity
dispersion, which play an important role on dwarf galaxy formation. In previous
theoretical studies of dwarf galaxies based on the monolithic cloud collapse
given by Yoshii & Arimoto and Dekel & Silk, the dynamical response was treated
in the extremes of a purely baryonic cloud and a baryonic cloud fully supported
by surrounding dark matter. To improve this simple treatment, in our previous
paper, we formulated the dynamical response in more realistic, intermediate
situations between the above extremes. While the effects of dynamical response
depend on the mass fraction of removed gas from a galaxy, how much amount of
the gas remains just after major merger depends on the star formation history.
A variety of star formation histories are generated through the Monte Carlo
realization of merging histories of dark halos, and it is found that our SAM
naturally makes a wide variety of dwarf galaxies and their dispersed
characteristics as observed. (Abridged)


title:
Type Ia supernovae in a hierarchical galaxy formation model: the Milky
  Way

abstract:
  We investigate chemical evolution in Milky Way-like galaxies based on the
cold dark matter model in which cosmic structures form via hierarchical
merging. We introduce chemical enrichment due to type Ia supernovae (SNe Ia)
into the Mitaka semi-analytic galaxy formation model developed by Nagashima &
Yoshii. For the first time we derive distributions of stellar metallicities and
their ratios in Milky Way-like galaxies treating chemical enrichment due to SNe
Ia in a hierarchical galaxy formation model self-consistently. As a first
attempt, we assume all SNe Ia to have the same lifetime, and assume
instantaneous recycling for type II supernovae (SNe II). We find that our model
reproduces well the metal abundance ratio [O/Fe] against [Fe/H] and the {iron
metallicity distribution function} in the solar neighborhood. This means that
the so-called G-dwarf problem is resolved by the hierarchical formation of
galaxies, and a gas infall term introduced in traditional monolithic collapse
models to solve this problem is well explained by the mixture of some physical
processes such as hierarchical merging of dark halos, gas cooling, energy
feedback and injection of gas and metals into hot gas due to supernovae. Our
model predicts more oxygen-enhanced stars in bulges at [Fe/H] $\simeq 0$ than
in disks. This trend seems to be supported by recent observations while they
have still uncertainties. More data in number and accuracy will provide
independent and important constraints on galaxy formation. (abridged)


title: Quasar Variability Measurements With SDSS Repeated Imaging and POSS Data

abstract:
  We analyze the properties of quasar variability using repeated SDSS imaging
data in five UV-to-far red photometric bands, accurate to 0.02 mag, for 13,000
spectroscopically confirmed quasars. The observed time lags span the range from
3 hours to over 3 years, and constrain the quasar variability for rest-frame
time lags of up to two years, and at rest-frame wavelengths from 1000 Ang. to
6000 Ang. We demonstrate that 66,000 SDSS measurements of magnitude differences
can be described within the measurement noise by a simple function of only
three free parameters. The addition of POSS data constrains the long-term
behavior of quasar variability and provides evidence for a turn-over in the
structure function. This turn-over indicates that the characteristic time scale
for optical variability of quasars is of the order 1 year.


title:
The Luminosity-Metallicity Relation of distant luminous infrared
  galaxies

abstract:
  One hundred and five 15mu selected objects in three ISO deep survey fields
(CFRS 3h, UDSR and UDSF) are studied on the basis of the high quality optical
spectra with resolution R>1000 from VLT/FORS2. Ninety two objects (88%) have
secure redshifts, ranging from 0 to 1.16 with a median value of 0.587.
Considerable care is taken in estimating the extinction property of individual
galaxy, which can seriously affect diagnostic diagrams and estimates of star
formation rates and of metal abundances. Two independent methods have been
adopted to estimate extinction, e.g. Balmer line ratio (A_V(Balmer)) and energy
balance between IR and Hbeta luminosities (A_V(IR)). For most of the z>0.4
luminous IR galaxies (LIRGs), the two extinction coefficients are consistent
well, with median values of A_V(IR) = 2.36. These distant LIRGs show many
properties strikingly in common with those of local (IRAS) LIRGs studied by
Veilleux et al. (1995). Our sample can provide a good representation of LIRGs
in the distant Universe. Most (>77%) ISO 15mu selected sample galaxies are
dominated by star formation. Oxygen abundances (12+log(O/H), derived from R23
and O32) in ISM in the distant LIRGs range from 8.36 to 8.93 with a median
value of 8.67. Distant LIRGs present a metal content less than half of that of
the local bright disks (i.e. L*). The Pegase2 models predict that total masses
(gas + stars) of the distant LIRGs are from 10^{11} Msun to <=10^{12} Msun. A
significant fraction of distant large disks are indeed LIRGs. Such massive
disks could have formed ~50% of their metals and stellar masses since z~1.


title: Evolution of dark-matter haloes in a variety of dark-energy cosmologies

abstract:
  High-resolution, numerical simulations of 17 cluster-sized dark-matter haloes
in eight different cosmologies with and without dynamical dark energy confirm
the picture that core halo densities are imprinted early during their formation
by the mean cosmological density. Quite independent of cosmology, halo
concentrations have a log-normal distribution with a scatter of ~0.2 about the
mean. We propose a simple scaling relation for halo concentrations in
dark-energy cosmologies.


title: Integral and Light Dark Matter

abstract:
  The nature of Dark Matter remains one of the outstanding questions of modern
astrophysics. The success of the Cold Dark Matter cosmological model argues
strongly in favor of a major component of the dark matter being in the form of
elementary particles, not yet discovered. Based on earlier theoretical
considerations, a possible link between the recent SPI/INTEGRAL measurement of
an intense and extended emission of 511 keV photons (positron annihilation)
from the central Galaxy, and this mysterious component of the Universe, has
been established advocating the existence of a light dark matter particle at
variance with the neutralino, in general considered as very heavy. We show that
it can explain the 511 keV emission mapped with SPI/INTEGRAL without
overproducing undesirable signals like high energy gamma-rays arising from
$\pi^\circ$ decays, and radio synchrotron photons emitted by high energy
positrons circulating in magnetic fields. Combining the annihilation line
constraint with the cosmological one (i.e. that the relic LDM energy density
reaches about 23% of the density of the Universe), one can restrict the main
properties of the light dark matter particle. Its mass should lie between 1 and
100 MeV, and the required annihilation cross section, velocity dependent,
should be significantly larger than for weak interactions, and may be induced
by the virtual production of a new light neutral spin 1 boson $U$. On
astrophysical grounds, the best target to validate the LDM proposal seems to be
the observation by SPI/INTEGRAL and future gamma ray telescopes of the
annihilation line from the Sagittarius dwarf galaxy and the Palomar-13 globular
cluster, thought to be dominated by dark matter.


title: INTEGRAL Observations of Cygnus X-3

abstract:
  The peculiar X-ray binary Cygnus X-3 has been observed on several occasions
with the X/gamma-ray instruments on board INTEGRAL. We have collected data from
available public and Galactic Plane Scan observations between December 2002 and
December 2003 and summed them together into two broad-band spectra,
representing different physical spectral states of the source. We have fitted
the two spectra with models including Comptonization and Compton reflection,
similar to those found for black-hole binaries at high accretion rates.


title: Hypernovae as possible sources of Galactic positrons

abstract:
  INTEGRAL/SPI has recently observed a strong and extended emission resulting
from electron-positron annihilation located in the Galactic center region,
consistent with the Galactic bulge geometry, without any counterpart at high
gamma-ray energies, nor in the 1809 keV $^{26}$Al decay line. In order to
explain the rate of positron injection in the Galactic bulge, estimated to more
than 10$^{43}$ s$^{-1}$, the most commonly considered positron injection
sources are type Ia supernovae. However, SN Ia rate estimations show that those
sources fall short to explain the observed positron production rate, raising a
challenging question about the nature of the Galactic positron source. In this
context, a possible source of Galactic positrons could be supernova events of a
new type, as the recently observed SN2003dh/GRB030329, an exploding Wolf-Rayet
star (type Ic supernova) associated with a hypernova/gamma-ray burst; the
question about the rate of this kind of events remains open, but could be
problematically low.
  In this paper, we explore the possibility of positron production and escape
by such an event in the framework of an asymmetric model, in which a huge
amount of $^{56}$Ni is ejected in a cone with a very high velocity; the ejected
material becomes quickly transparent to positrons, which spread out in the
interstellar medium.


title: X-ray flares from the ultra-luminous X-ray source in NGC 5408

abstract:
  We have studied an ultra-luminous X-ray source (ULX) in the dwarf galaxy NGC
5408 with a series of XMM-Newton observations, between 2001 July and 2003
January. We find that its X-ray spectrum is best fitted with a power law of
photon index Gamma ~ 2.6--2.9 and a thermal component with blackbody
temperature kT_bb ~ 0.12--0.14 keV. These spectral features, and the inferred
luminosity ~ 10^{40} erg/s in the 0.3--12 keV band, are typical of bright ULXs
in nearby dwarf galaxies. The blackbody plus power-law model is a significantly
better fit than either a simple power law or a broken power law (although the
latter model is also acceptable at some epochs). Doppler-boosted emission from
a relativistic jet is not required, although we cannot rule out this scenario.
Our preliminary timing analysis shows flaring behaviour which we interpret as
variability in the power-law component, on timescales of ~ 10^2 s. The hard
component is suppressed during the dips, while the soft thermal component is
consistent with being constant. The power density spectrum is flat at low
frequencies, has a break at f_b ~ 2.5 mHz, and has a slope ~ -1 at higher
frequencies. A comparison with the power spectra of Cyg X-1 and of a sample of
other BH candidates and AGN suggests a mass of ~ 10^2 M_sun. It is also
possible that the BH is at the upper end of the stellar-mass class (M ~ 50
M_sun), in a phase of moderately super-Eddington accretion. The formation of
such a massive BH via normal stellar evolution may have been favoured by the
very metal-poor environment of NGC 5408.


title: Atypical k-essence cosmologies

abstract:
  We analyze the implications of having a divergent speed of sound in k-essence
cosmological models. We first study a known theory of that kind, for which the
Lagrangian density depends linearly on the time derivative of the k-field. We
show that when k-essence is the only source consistency requires that the
potential of the k-field be of the inverse square form. Then, we review the
known result that the corresponding power-law solutions can be mapped to
power-law solutions of theories with no divergence in the speed of sound. After
that, we argue that the requirement of a divergent sound speed at some point
fixes uniquely the form of the Lagrangian to be exactly the one considered
earlier and prove the asymptotic stability of the most interesting solutions
belonging to the divergent theory. Then, we discuss the implications having not
just k-essence but also matter. This is interesting because introducing another
component breaks the rigidity of the theory, and the form of the potential
ceases to be unique as happened in the pure k-essence case. Finally, we show
the finiteness of the effective sound speed under an appropiate definition.


title:
Carina's Defiant Finger: HST Observations of a Photoevaporating Globule
  in NGC3372

abstract:
  We present HST/WFPC2 images of a prominent externally-ionized molecular
globule in the Carina Nebula (NGC3372), supplemented with ground-based IR
images and visual-wavelength spectra. This molecular globule has a shape
resembling a human hand, with an extended finger that points toward its likely
source of ionizing radiation. The dominant ionizing source of the globule is
either the WNL star WR25 (HD93162), the O4 If-type star Tr16-244, or perhaps
both. We estimate a mass-loss rate of ~2e-5 Msun/yr from the main evaporating
surface of the globule, suggesting a remaining lifetime of 10^5.3 to 10^6
years. We find a total mass for the entire globule of more than 6 Msun, in
agreement with previous estimates. The hydrogen column density through the
globule is a few times 10^22/cm2. Although a few reddened stars are seen within
the boundary of the globule in near-IR continuum images, these may be
background stars. We do not detect a reddened star at the apex of the finger,
for example, down to a limiting magnitude of K=17. However, considering the
physical properties of the globule and the advancing ionization front, it
appears that future star formation is likely in the Finger globule, induced by
radiation-driven implosion.


title:
Three-dimensional Simulations of Disk Accretion to an Inclined Dipole:
  II. Hot Spots and Variability

abstract:
  The physics of the "hot spots" on stellar surfaces and the associated
variability of accreting magnetized rotating stars is investigated for the
first time using fully three-dimensional magnetohydrodynamic simulations. The
magnetic moment of the star is inclined relative to its rotation axis by an
angle Theta. A sequence of misalignment angles was investigated, between
Theta=0 and 90 degrees.Typically at small Theta the spots are observed to have
the shape of a bow which is curved around the magnetic axis, while at largest
Theta the spots have a shape of a bar, crossing the magnetic pole. The physical
parameters (density, temperature, etc.) increase toward the central regions of
the spots. At relatively low density and temperature, the spots occupy
approximately 10-20 % of the stellar surface, while at the highest values of
these parameters this area may be less than 1 % of the area of the star. The
light curves were calculated for different Theta and inclination angles of the
disk i. They show a range of variability patterns, including one
maximum-per-period curves (at most of angles Theta and i), and two
maximum-per-period curves (at large Theta and i). At small Theta, the funnel
streams may rotate faster/slower than the star, and this may lead to
quasi-periodic variability of the star. The results are of interest for
understanding the variability and quasi-variability of Classical T Tauri Stars,
millisecond pulsars and cataclysmic variables.


title: Anthropic predictions for vacuum energy and neutrino masses

abstract:
  It is argued that the observed vacuum energy density and the small values of
the neutrino masses could be due to anthropic selection effects. Until now,
these two quantities have been treated separately from each other and, in
particular, anthropic predictions for the vacuum energy were made under the
assumption of zero neutrino masses. Here we consider two cases. In the first,
we calculate predictions for the vacuum energy for a fixed (generally non-zero)
value of the neutrino mass. In the second we allow both quantities to vary from
one part of the universe to another. We find that the anthropic predictions for
the vacuum energy density are in a better agreement with observations when one
allows for non-zero neutrino masses. We also find that the individual
distributions for the vacuum energy and the neutrino masses are reasonably
robust and do not change drastically when one adds the other variable.


title: Radio halos in merging clusters of galaxies

abstract:
  We present the preliminary results of 235 MHz, 327 MHz and 610 MHz
observations of the galaxy cluster A3562 in the core of the Shapley
Concentration. The purpose of these observations, carried out with the Giant
Metrewave Radio Telescope (GMRT, Pune, India) was to study the radio halo
located at the centre of A3562 and determine the shape of its radio spectrum at
low frequencies, in order to understand the origin of this source. In the
framework of the re--acceleration model, the preliminary analysis of the halo
spectrum suggests that we are observing a young source (few $10^8$ yrs) at the
beginning of the re--acceleration phase.


title:
Search for a light dark matter annihilation signal in the Sagittarius
  Dwarf Galaxy

abstract:
  The 511 keV emission from the Galactic Bulge observed by INTEGRAL/SPI could
be the product of light (1-100 MeV) annihilating dark matter particles. In
order to distinguish between annihilating light dark matter scenarios and more
conventional astrophysical sources for the bulge emission, we propose to test
the light dark matter hypothesis on the Sagittarius Dwarf Galaxy, a close-by
galaxy dominated by dark matter. The predicted flux being in the SPI
sensitivity range, the detection of a substantial 511 keV emission line from
this galaxy would provide a strong evidence for the light dark matter
hypothesis.
  During the two Galactic Center Deep Exposures performed in 2003, the
Sagittarius Dwarf Galaxy was in the field of view of several INTEGRAL
observations. In this paper we present preliminary results of the analysis of
these data.


title: On the Stability of Thermonuclear Burning Fronts in Type Ia Supernovae

abstract:
  The propagation of cellularly stabilized thermonuclear flames is investigated
by means of numerical simulations. In Type Ia supernova explosions the
corresponding burning regime establishes at scales below the Gibson length. The
cellular flame stabilization - which is a result of an interplay between the
Landau-Darrieus instability and a nonlinear stabilization mechanism - is
studied for the case of propagation into quiescent fuel as well as interaction
with vortical fuel flows. Our simulations indicate that in thermonuclear
supernova explosions stable cellular flames develop around the Gibson scale and
that deflagration-to-detonation transition is unlikely to be triggered from
flame evolution effects here.


title:
Astrophysical gamma-ray lines: a probe of stellar nucleosynthesis and
  star formation

abstract:
  Astrophysical gamma-ray spectroscopy is a most valuable tool for studying
nuclear astrophysics, as well as recent star formation in the Milky Way. After
a short, historical, introduction to the field, I present a brief review of the
most important current issues. Emphasis is given to radioactivities produced by
massive stars and associated supernova explosions, and in particular, those
related to observations presently carried out by INTEGRAL: short-lived Ti-44
from CasA and SN1987A and long-lived Al-26 and Fe-60 from massive stars;
various candidate sources of positrons for the 511 keV emission of the Galactic
bulge are also critically discussed.


title:
Three-dimensional simulations of the interstellar medium in dwarf
  galaxies - II. Galactic wind

abstract:
  We study the hydrodynamical evolution of galactic winds in disky dwarf
galaxies moving through an intergalactic medium. In agreement with previous
investigations,we find that when the ram pressure stripping does not disrupt
the ISM, it usually has a negligible effect on the galactic wind dynamics. Only
when the IGM ram pressure is comparable to the central ISM thermal pressure the
stripping and the superwind influence each other increasing the gas removal
rate. In this case several parameters regulate the ISM ejection process, as the
original distribution of the ISM and the geometry of the IGM-galaxy
interaction. When the ISM is not removed by the ram pressure or the wind, it
loses memory of the starburst episode and recovers almost its pre-burst
distribution in a timescale of 50-200 Myr. After this time another star
formation episode becomes, in principle, possible. Evidently, galactic winds
are consistent with a recurrent bursts star formation history.
  Contrary to the ISM content, the amount of the metal-rich ejecta retained by
the galaxy is more sensitive to the ram pressure action. Part of the ejecta is
first trapped in a low density, extraplanar gas produced by the IGM-ISM
interaction, and then pushed back onto the galactic disc. The amount of trapped
metals in a moving galaxy may be up to three times larger than in a galaxy at
rest. This prediction may be tested comparing metallicity of dwarf galaxies in
nearby poor clusters or groups, such as Virgo or Fornax, with the field
counterpart. The sensitivity of the metal entrapment efficiency on the geometry
of the interaction may explain part of the observed scatter in the
metallicity-luminosity relation for dwarf galaxies.


title: Multiwavelength View of SDSS Galaxies

abstract:
  We summarize the detection rates at wavelengths other than optical for
\~99,000 galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 1
``main'' spectroscopic sample. The analysis is based on positional
cross-correlation with source catalogs from ROSAT, 2MASS, IRAS, GB6, FIRST,
NVSS and WENSS surveys. We find that the rest-frame UV-IR broad-band galaxy
SEDs form a remarkably uniform, nearly one parameter, family. As an example,
the SDSS u and r band data, supplemented with redshift, can be used to predict
K band magnitudes measured by 2MASS with an rms scatter of only 0.2 mag; when
measurement uncertainties are taken into account, the astrophysical scatter
appears not larger than ~0.1 mag.


title: Modeling the accretion history of supermassive black holes

abstract:
  There is overwhelming evidence for the presence of supermassive black holes
(SMBHs) in the centers of most nearby galaxies. The mass estimates for these
remnant black holes from the stellar kinematics of local galaxies and the
quasar phenomenon at high redshifts point to the presence of assembled SMBHs.
The accretion history of SMBHs can be reconstructed using observations at high
and low redshifts as model constraints. Observations of galaxies and quasars in
the submillimeter, infrared, optical, and X-ray wavebands are used as
constraints, along with data from the demography of local black holes.
Theoretical modeling of the growth of black hole mass with cosmic time has been
pursued thus far in two distinct directions: a phenomenological approach that
utilizes observations in various wavebands, and a semi-analytic approach that
starts with a theoretical framework and a set of assumptions with a view to
matching observations. Both techniques have been pursued in the context of the
standard paradigm for structure formation in a Cold Dark Matter dominated
universe. Here, we examine the key issues and uncertainties in the theoretical
understanding of the growth of SMBHs.


title: Dynamical segregation of galaxies in groups and clusters

abstract:
  We have performed a systematic analysis of the dynamics of different galaxy
populations in galaxy groups from the 2dFGRS. For this purpose we have combined
all the groups into a single system, where velocities v and radius r are
expressed adimensionally. We have used several methods to compare the
distributions of relative velocities of galaxies with respect to the group
centre for samples selected according to their spectral type (as defined by
Madgwick et al., 2002), bj band luminosity and B-R colour index. We have found
strong segregation effects: spectral type I objects show a statistically
narrower velocity distribution than that of galaxies with a substantial star
formation activity (type II-IV). Similarly, the same behavior is observed for
galaxies with colour index B-R>1 compared to galaxies with B-R<1. Bright
(Mb<-19) and faint (Mb>-19) galaxies show the same segregation. It is not
important once the sample is restricted to a given spectral type. These effects
are particularly important in the central region (Rp<Rvirial/2) and do not have
a strong dependence on the mass of the parent group. These trends show a strong
correlation between the dynamics of galaxies in groups and star formation rate
reflected both by spectral type and by colour index.


title:
The Ultraviolet Spectra of Active Galaxies With Double-Peaked Emission
  Lines

abstract:
  We present the results of UV spectroscopy of AGNs with double-peaked Balmer
emission lines. In 2/3 of the objects, the far-UV resonance lines are strong,
with single-peaked profiles resembling those of Seyfert galaxies. The Mg II
line is the only UV line with a double-peaked profile. In the remaining
objects, the far-UV resonance lines are relatively weak but still
single-peaked. The latter group also displays prominent UV absorption lines,
indicative of a low-ionization absorber. We interpret the difference in the
profiles of the emission lines as resulting from two different regions: a
dense, low-ionization accretion disk (the predominant source of the Balmer and
Mg II lines), and a lower density, higher-ionization wind (the predominant
source of the far-UV resonance lines). These results suggest a way of
connecting the double-peaked emitters with the greater AGN population: in
double-peaked emitters the accretion rate onto the black hole is low, making
the wind feeble and allowing the lines from the underlying disk to shine
through. This scenario also implies that in the majority of AGNs, the wind is
the source of the broad emission lines.


title: Non-thermal phenomena in galaxies clusters

abstract:
  The discovery of diffuse synchrotron radio emission and, more recently, of
the hard X-ray (HXR) tails have triggered a growing interest about non-thermal
phenomena in galaxy clusters. After a brief review of the most important
evidences for non-thermal emission, I will focus on the origin of the emitting
particles and of the hadronic component. In particular I will describe the
particle-injection and -acceleration mechanisms at work in the intra-cluster
medium (ICM) and, at the same time, discuss the possibility to test current
modellings of these phenomena with future radio, HXR, and gamma rays
observatories.


title: Detection of Atomic Chlorine in Io's Atmosphere with HST/GHRS

abstract:
  We report the detection of atomic chlorine emissions in the atmosphere of Io
using Hubble Space Telescope observations with the Goddard High Resolution
Spectrograph (GHRS). The Cl I 1349 A dipole allowed and Cl I] 1386 A forbidden
transition multiplets are detected at a signal to noise ratio (SNR) of 6 and
10, respectively, in a combined GHRS spectrum acquired from 1994 through 1996.
Oxygen and sulfur emissions are simultaneously detected with the chlorine which
allows for self-consistent abundance ratios of chlorine to these other
atmospheric species. The disk averaged ratios are: Cl/O = 0.017 +/- 0.008, Cl/S
= 0.10 +/- 0.05, and S/O = 0.18 +/- 0.08. We also derive a geometric albedo of
1.0 +/- 0.4 % for Io at 1335 A assuming an SO2 atmospheric column density of
1x10^{16} cm^{-2}.


title:
Cluster Mergers, Radio Halos and Hard X-ray Tails: A Statistical
  Magneto-Turbulent Model

abstract:
  There is now firm evidence that the ICM consists of a mixture of hot plasma,
magnetic fields and relativistic particles. The most important evidences for
non-thermal phenomena in galaxy clusters comes from the diffuse Mpc-scale
synchrotron radio emission (radio halos) observed in a growing number of
massive clusters (Feretti 2003) and from hard X-ray (HXR) excess emission
(detected in a few cases) which can be explained in terms of IC scattering of
relativistic electrons off the cosmic microwave background photons
(Fusco-Femiano et al. 2003). There are now growing evidences that giant radio
halos may be naturally accounted for by synchrotron emission from relativistic
electrons reaccelerated by some kind of turbulence generated in the cluster
volume during merger events (Brunetti 2003). With the aim to investigate the
connection between thermal and non-thermal properties of the ICM, we have
developed a statistical magneto-turbulent model which describes the evolution
of the thermal and non-thermal emission from clusters. We calculate the energy
and spectrum of the magnetosonic waves generated during cluster mergers, the
acceleration and evolution of relativistic electrons and thus the resulting
synchrotron and inverse Compton spectra. Here we give a brief description of
the main results, while a more detailed discussion will be presented in a
forthcoming paper. Einstein-De Sitter cosmology, $H_o=50$ km
$s^{-1}$$Mpc^{-1}$, $q_o=0.5$, is assumed.


title: Universal Limits on Computation

abstract:
  The physical limits to computation have been under active scrutiny over the
past decade or two, as theoretical investigations of the possible impact of
quantum mechanical processes on computing have begun to make contact with
realizable experimental configurations. We demonstrate here that the observed
acceleration of the Universe can produce a universal limit on the total amount
of information that can be stored and processed in the future, putting an
ultimate limit on future technology for any civilization, including a
time-limit on Moore's Law. The limits we derive are stringent, and include the
possibilities that the computing performed is either distributed or local. A
careful consideration of the effect of horizons on information processing is
necessary for this analysis, which suggests that the total amount of
information that can be processed by any observer is significantly less than
the Hawking-Bekenstein entropy associated with the existence of an event
horizon in an accelerating universe.


title:
Higher-order Balmer line indices in alpha/Fe-enhanced stellar population
  models

abstract:
  We have computed the higher-order Balmer absorption line indices Hgamma and
Hdelta (Worthey & Ottaviani 1997) for stellar population models with variable
element ratios. The response of these indices to abundance ratio variations is
taken from detailed line formation and model atmosphere calculations. We find
that Hgamma and Hdelta, unlike Hbeta, are very sensitive to alpha/Fe ratio
changes at super-solar metallicities. Both line indices increase significantly
with increasing alpha/Fe ratio. This effect cannot be neglected when these line
indices are used to derive the ages of metal-rich, unresolved stellar
populations like early-type galaxies. We re-analyze the elliptical galaxy
sample of Kuntschner (2000), and show that consistent age estimates from Hbeta
and Hgamma are obtained, only if the effect of alpha/Fe enhancement on Hgamma
is taken into account in the models. This result rectifies a problem currently
present in the literature, namely that Hgamma and Hdelta have up to now led to
significantly younger ages for early-type galaxies than Hbeta. Our work
particularly impacts on the interpretation of intermediate to high-redshift
data, for which only the higher-order Balmer lines are accessible
observationally.


title: A Measurement of the Electromagnetic Luminosity of a Kerr Black Hole

abstract:
  Some active galactic nuclei, microquasars, and gamma ray bursts may be
powered by the electromagnetic braking of a rapidly rotating black hole. We
investigate this possibility via axisymmetric numerical simulations of a black
hole surrounded by a magnetized plasma. The plasma is described by the
equations of general relativistic magnetohydrodynamics, and the effects of
radiation are neglected. The evolution is followed for $2000 G M/c^3$, and the
computational domain extends from inside the event horizon to typically $40 G
M/c^2$. We compare our results to two analytic steady state models, including
the force-free magnetosphere of Blandford & Znajek. Along the way we present a
self-contained rederivation of the Blandford-Znajek model in Kerr-Schild
(horizon penetrating) coordinates. We find that (1) low density polar regions
of the numerical models agree well with the Blandford-Znajek model; (2) many of
our models have an outward Poynting flux on the horizon in the Kerr-Schild
frame; (3) none of our models have a net outward energy flux on the horizon;
and (4) one of our models, in which the initial disk has net magnetic flux,
shows a net outward angular momentum flux on the horizon. We conclude with a
discussion of the limitations of our model, astrophysical implications, and
problems to be addressed by future numerical experiments.


title: The 2003 Shell Event in eta Carinae

abstract:
  Near-infrared, JHKL, photometry of eta Car is reported covering the period
2000 to 2004. This includes the 2003 shell event which was the subject of an
international multi-wavelength campaign. The fading that accompanied this event
was similar to, although slightly deeper than, that which accompanied the
previous one. The period between these events is 2023+/-3 days and they are
strictly periodic. Their cause, as well as that of the quasi-periodic
variations and secular brightening are discussed. It seems possible that all
three types of variability are consequences of the binary nature of the star.


title: The Formation of the Most Relativistic Pulsar PSR J0737-3039

abstract:
  We present an updated set of constraints for the progenitor of PSR J0737-3039
and for the natal kicks imparted to pulsar B taking into account both the
evolutionary and kinematic history of the double neutron star. For this
purpose, we use recently reported scintillation velocity measurements to trace
the motion of the system in the Galaxy backwards in time as a function of the
unknown orientation Omega of the systemic velocity projected on plane of the
sky as well as the unknown radial velocity Vr. The absolute limits on the
orbital separation and the mass of pulsar B's helium star progenitor just
before its supernova explosion are 1.2Rsun < A0 < 1.7Rsun and 2.1Msun < M0 <
4.7Msun. The kick velocity is constrained to be between 60km/s and 1660km/s and
to be misaligned from the pre-SN orbital angular axis (which could be
associated with pulsar B's spin axis) by least 25 degrees. We also derive
probability distribution functions for the kick velocity imparted to pulsar B
and for the misalignment angle between pulsar A's spin and the post-supernova
orbital angular momentum for both isotropic and polar kicks. The most probable
values of both quantities depend sensitively on the unknown radial velocity. In
particular, tilt angles lower than 30-50 degrees tend to be favored for current
radial velocities of less than 500km/s in absolute value, while tilt angles
higher than 120 degrees tend to be associated with radial velocities in excess
of 1000km/s in absolute value.


title:
Supernova explosions, 511 keV photons, gamma ray bursts and mirror
  matter

abstract:
  There are three astroparticle physics puzzles which fire the imagination: the
origin of the ``Great Positron Producer'' in the galactic bulge, the nature of
the gamma-ray bursts central engine and the mechanism of supernova explosions.
We show that the mirror matter model has the potential to solve all three of
these puzzles in one beautifully simple strike.


title: Molecular fraction limits in damped Lyman-alpha absorption systems

abstract:
  We have used the Green Bank Telescope (GBT) and Berkeley-Illinois-Maryland
Association (BIMA) array to search for redshifted millimetre absorption in a
sample of damped Lyman-alpha absorption systems (DLAs). This brings the number
of published systems searched from 18 to 30. In 17 cases we reach $3\sigma$
limits of $\tau\leq0.1$, which is a significant improvement over the previous
searches and more than sufficient to detect the 4 known redshifted millimetre
absorbers ($\tau\gapp1$). While the CO rotational (millimetre) column density
limits obtained are weaker than the electronic (optical) limits, they may
provide useful limits below the atmospheric cut-off for the Lyman and Werner
\MOLH-bands in the UV ($z_{\rm abs}\lapp1.8$). Using a model for the DLA
metallicity evolution combined with assumed HCO$^+$/\MOLH ~and CO/\MOLH
\~conversion ratios, we use the molecular column density limits to calculate
plausible \MOLH ~molecular fraction limits. Finally, we use these results to
discuss the feasibility of detecting rotational CO transitions in DLAs with the
next generation of large radio telescopes.


title:
A Survey For Infall Motions Toward Starless Cores. III. CS (3-2) and
  DCO+(2-1) Observations

abstract:
  We present CS(3-2) and DCO+(2-1) observations of 94 starless cores and
compare the results with previous CS(2-1) and N2H+(1-0) observations to study
inward motions in starless cores. The velocity shifts of the CS(3-2) and (2-1)
lines with respect to N2H+ correlate well with each other and have similar
distributions. This implies that, in many cores, systematic inward motions of
gaseous material may occur over a range of density of at least a factor 4. We
identify 18 infall candidates based on observations of CS(3-2), CS(2-1),
DCO+(2-1) and N2H+(1-0). The eight best candidates, L1355, L1498, L1521F,
L1544, L158, L492, L694-2, and L1155C-1, each show at least four indications of
infall asymmetry and no counter-indications. Fits of the spectra to a 2-layer
radiative transfer model in ten infall candidates suggest that the median
effective line-of-sight speed of the inward-moving gas is ~0.07 km/s for CS
(3-2) and ~0.04 km/s for CS(2-1). Considering that the optical depth obtained
from the fits is usually smaller in CS(3-2) than in (2-1) line, this may imply
that CS(3-2) usually traces inner denser gas in higher inward motions than
CS(2-1). However, it is also possible that this conclusion is not
representative of all starless core infall candidates, due to the statistically
small number analyzed here. Further line observations will be useful to test
this conclusion.


title: Magnetic Field Evolution During Neutron Star Recycling

abstract:
  I describe work on two aspects of magnetic field evolution relevant for the
"recycling" scenario for making millisecond radio pulsars. First, many of the
theoretical ideas for bringing about accretion-induced field decay rely on
dissipation of currents in the neutron star crust. I discuss field evolution in
the crust due to the Hall effect, and outline when it dominates Ohmic decay.
This emphasises the importance of understanding the impurity level in the
crust. Second, I briefly discuss the progress that has been made in
understanding the magnetic fields of neutron stars currently accreting matter
in low mass X-ray binaries. In particular, thermonuclear X-ray bursts offer a
promising probe of the magnetic field of these neutron stars.


title: Pre-inflation models and WMAP data

abstract:
  The effect of pre-inflation physics on the power spectrum of scalar
perturbations is estimated and there is a possibility that the pre-inflation
physics explains the Wilkinson Microwave Anisotropy Probe data if the length of
inflation is near 60 e-folds. Considering various pre-inflation models with
radiation-dominated or matter-dominated periods before inflation, the power
spectrum of curvature perturbations for large scales is calculated, and the
spectral index and running spectral index are derived.


title:
Effect of Strong Quantizing Magnetic Field on the Transport Properties
  of Dense Stellar Plasma

abstract:
  The transport properties of dense stellar electron-proton plasma is studied
following an exact relativistic formalism in presence of strong quantizing
magnetic field. The variation of transport coefficients with magnetic field are
found to be insensitive for the field strengths $\leq 10^{17}$G, beyond which
all of them abruptly go to zero. As a consequence, the electron-proton plasma
behaves like a superfluid insulator in presence of ultra-strong magnetic field.


title: The interplay between radio-activity and the ISM in radio galaxies

abstract:
  Radio-loud AGNs can inhabit regions with a very rich ISM. The presence of
this rich medium is likely related to the origin and evolution of the host
galaxy and of the active nucleus. Recent observations show that a large
fraction of radio galaxies contains a significant young stellar population.
This supports the idea that mergers are responsible for both the starburst
phase and the triggering of the nuclear activity. The gas that reaches the
central regions can have quite disturbed kinematics, likely due to the effects
of the AGN activity and in particular of the powerful radio jets. The recent
detection of fast nuclear gas outflows, observed both in ionised and neutral
gas, is giving new and important insights into the physical conditions of the
gaseous medium around the nucleus and the interaction between the AGN and this
medium. Finally, as another example of the interplay between the radio activity
and the ISM, the possibility of star formation induced by the passage of the
radio jet will be discussed.


title: Fast Outflows of Neutral Hydrogen in Radio Galaxies

abstract:
  AGN activity is known to drive fast outflows of gas. We report the discovery
of fast outflows of neutral gas with velocities over 1000 km/s in a number of
radio galaxies. In the best studied object, 3C~293, the kinematical properties
of the neutral and ionised outflows are similar, indicating a common origin.
Moreover, the outflow appears to be located near the radio lobes and not near
the nucleus. This suggests that the interaction between the radio jet and the
ISM is driving the outflow.


title:
The Optical Gravitational Lensing Experiment. The New Catalog of
  Eclipsing Binary Stars in the Small Magellanic Cloud

abstract:
  We present new version of the OGLE-II catalog of eclipsing binary stars
detected in the Small Magellanic Cloud, based on Difference Image Analysis
catalog of variable stars in the Magellanic Clouds containing data collected
from 1997 to 2000. We found 1351 eclipsing binary stars in the central 2.4
square degree area of the SMC. 455 stars are newly discovered objects, not
found in the previous release of the catalog. The eclipsing objects were
selected with the automatic search algorithm based on the artificial neural
network. The full catalog is accessible from the OGLE Internet archive.


title:
Search for fast correlated X-ray and optical variability in Cir X-1 and
  XTE J1746-321

abstract:
  Coordinated observations X-ray+optical observations of two southern X-ray
binaries, the black hole candidate XTE J1746-321 and the neutron star accreter
Cir X-1 (a `microquasar') are reported. With a photon counting optical
photometer on the 1.9m telescope at Sutherland, South Africa and the PCA
detector on RXTE, 4h each of simultaneous data were obtained on XTE J1746 and
Cir X-1. Cir X-1 showed no X-ray variability at the 2% level, XTE J1746 was
variable at 5-7% with a 5Hz QPO. Cross-correlation yielded no correlated
signals on either source, to a level of 1%. A problem with a recently published
orbital ephemeris of Cir X-1 is pointed out.