title:
The Evolution and Simulation of the Outburst from XZ Tauri - A Possible
  EXor?

abstract:
  We report on multi-epoch HST/WFPC2 images of the XZ Tauri binary, and its
outflow, covering the period from 1995 to 2001. Data from 1995 to 1998 have
already been published in the literature. Additional images, from 1999, 2000
and 2001 are presented here. These reveal not only further dynamical and
morphological evolution of the XZ Tauri outflow but also that the suspected
outflow source, XZ Tauri North has flared in EXor-type fashion. In particular
our proper motion studies suggests that the recently discovered bubble-like
shock, driven by the the XZ Tauri outflow, is slowing down (its tangential
velocity decreasing from 146km/s to 117km/s). We also present simulations of
the outflow itself, with plausible ambient and outflow parameters, that appear
to reproduce not only the dynamical evolution of the flow, but also its shape
and emission line luminosity.


title: Galactic Structure

abstract:
  Our Milky Way Galaxy is a typical large spiral galaxy, representative of the
most common morphological type in the local Universe. We can determine the
properties of individual stars in unusual detail, and use the characteristics
of the stellar populations of the Galaxy as templates in understanding more
distant galaxies. The star formation history and merging history of the Galaxy
is written in its stellar populations; these reveal that the Galaxy has evolved
rather quietly over the last ~10 Gyr. More detailed simulations of galaxy
formation are needed, but this result apparently makes our Galaxy unusual if
Lambda CDM is indeed the correct cosmological paradigm for structure formation.
While our Milky Way is only one galaxy, a theory in which its properties are
very anomalous most probably needs to be revised. Happily, observational
capabilities of next-generation facilities should, in the the forseeable
future, allow the aquisition of detailed observations for all galaxies in the
Local Group.


title: Compressible 2D MHD modelling of prominence dips

abstract:
  An analytical MHD model of a normal-polarity prominence with compressible
flow is presented. The exact solution is constructed via a systematic nonlinear
separation of variables method used to calculate several classes of MHD
equilibria in Cartesian geometry and uniform gravity. Although the model is 2D,
a third magnetic/velocity vector field component is included and the highly
sheared fields observed in prominences are reproduced. A description is given
of the balance of gas pressure gradient with gravity and the Lorentz or
inertial forces acting along and across the prominence. It is found that the
flow does not significantly influence the heating profile. The analyzed model
has dimensions, plasma density, temperature and velocity profiles which agree
with those in the observations literature.


title: X-ray afterglows and spectroscopy of Gamma-Ray Bursts

abstract:
  I will review the constraints set by X-ray measurements of afterglows on
several issues of GRB, with particular regard to the fireball model, the
environment, the progenitor and dark GRB.


title:
Drilled by the jet? XMM-Newton discovers a Compton-thick AGN in the GPS
  galaxy Mkn668

abstract:
  We report the XMM-Newton discovery of the first Compton-thick obscured AGN in
a Broad Line Radio Galaxy, the Gigahertz Peaked-Spectrum source Mkn668
(OQ+208). The remarkably flat 2-10 keV X-ray spectrum (observed photon index,
\Gamma ~ 0.7), alongside with a prominent iron K-alpha fluorescent emission
line, is a clear signature of a Compton-reflection dominated spectrum. Mkn688
represents a remarkable example of discrepancy between X-ray spectral
properties and optical classification, as its optical spectrum is characterized
by broad and asymmetric Balmer lines. The obscuring matter is constrained to be
located within the radio hotspots, in turn separated by about 10 pc. If the
jets are piercing their way through a Compton-thick medium pervading the
nuclear environment, one could be largely underestimating the radio activity
dynamical age determined from the observed hotspot recession velocity. The soft
X-ray spectrum is dominated by a much steeper component, which may be due to
nuclear continuum electron scattering, or inverse Compton of the - remarkably
large - far infrared emission. Soft X-rays are suppressed by a further
Compton-thin (N_H ~ 10^21/cm/cm) absorbing system, that we identify with matter
responsible for free-free absorption of the radio lobes.


title:
Lagrangian perturbation theory of nonrelativistic rotating superfluid
  stars

abstract:
  We develop a Lagrangian perturbation framework for rotating non-relativistic
superfluid neutron stars. This leads to the first generalization of classic
work on the stability properties of rotating stars to models which account for
the presence of potentially weakly coupled superfluid components. Our analysis
is based on the standard two-fluid model expected to be relevant for the
conditions that prevail in the outer core of mature neutron stars. We discuss
the implications of our results for dynamical and secular instabilities of a
simple neutron star model in which the two fluids are allowed to assume
different (uniform) rotation rates.


title: X-ray spectroscopy of Gamma-Ray Bursts

abstract:
  In this review we briefly summarize the recent developments in the research
on Gamma-Ray Bursts, and discuss in more details the recent results derived
from X-ray spectroscopy, in particular the detection of X-ray narrow features
and their implication on our understanding on the origin of GRB. Finally, we
outline the importance of high resolution spectroscopy in X-rays, which can
provide new clues on the nature of progenitors, and a powerful probe of the
early Universe and primordial galaxy formation .


title: Evolution of Planets in Disks

abstract:
  The main properties of the observed extrasolar planets are reviewed with
respect to their relevance to the formation scenario of planetary systems.
Results of numerical computations of embedded planets in viscously evolving
disks are presented. Emphasis is given to the accretion and migration process.
New calculations on inviscid disks are shown.
  The second part of the talk concentrates on resonant planetary systems. Among
the observed extrasolar systems there are 3 confirmed cases, Gl 876, HD 82943
and 55 Cnc, where the planets orbit their central star in a low order mean
motion resonance. Results of numerical simulations modeling the formation and
evolution of such systems are presented.


title:
Accretion around supermassive black holes: the detection of the Balmer
  edge signature from quasars

abstract:
  The ultraviolet/optical continuum of quasars is thought to be from an
accretion flow around a supermassive black hole, and it dominates the radiative
output of quasars. However, the nature of this emission, often called the Big
Blue Bump, has not been well understood. Robust evidence for its thermal nature
would be a continuum opacity edge feature intrinsic to this component, but this
has not been clearly confirmed despite the predictions by many models. We are
now developing and exploiting a new method to detect the Balmer edge of
hydrogen opacity. The method overcomes for certain objects the major obstacle
of the heavy contamination from emissions outside the nucleus by taking the
polarized flux spectrum. If our interpretation of the polarized flux is
correct, our data show that the Big Blue Bump emission has a Balmer edge in
absorption, indicating that the emission is indeed thermal, and the emitter is
optically thick.


title: Late evolution of the X-ray afterglow of GRB 030329

abstract:
  The X-ray afterglow of the Gamma-Ray Burst GRB 030329, associated to SN2003dh
at z=0.1685, has been observed with XMM-Newton 258 days after the burst
explosion. A source with flux of (6.2 +/- 2.3) 10^{-16} erg cm^{-2} s^{-1}
(0.5-2 keV) has been detected at the GRB position. This measurement, together
with a re-analysis of the previous X-ray observations, indicates a flattening
of the X-ray light curve ~40 days after the burst. This is in remarkable
agreement with the scenario invoking the presence of two jets with different
opening angles. The wider jet should be responsible for the observed flattening
due to its transition into the non-relativistic Sedov-Taylor phase.


title: Particle Acceleration in an Evolving Network of Unstable Current Sheets

abstract:
  We study the acceleration of electrons and protons interacting with
localized, multiple, small-scale dissipation regions inside an evolving,
turbulent active region. The dissipation regions are Unstable Current Sheets
(UCS), and in their ensemble they form a complex, fractal, evolving network of
acceleration centers. Acceleration and energy dissipation are thus assumed to
be fragmented. A large-scale magnetic topology provides the connectivity
between the UCS and determines in this way the degree of possible multiple
acceleration. The particles travel along the magnetic field freely without
loosing or gaining energy, till they reach a UCS. In a UCS, a variety of
acceleration mechanisms are active, with the end-result that the particles
depart with a new momentum. The stochastic acceleration process is represented
in the form of Continuous Time Random Walk (CTRW), which allows to estimate the
evolution of the energy distribution of the particles. It is found that under
certain conditions electrons are heated and accelerated to energies above 1 MeV
in much less than a second. Hard X-ray (HXR) and microwave spectra are
calculated from the electrons' energy distributions, and they are found to be
compatible with the observations. Ions (protons) are also heated and
accelerated, reaching energies up to 10 MeV almost simultaneously with the
electrons. The diffusion of the particles inside the active region is extremely
fast (anomalous super-diffusion). Although our approach does not provide
insight into the details of the specific acceleration mechanisms involved, its
benefits are that it relates acceleration to the energy release, and it well
describes the stochastic nature of the acceleration process.


title: Neutrinos and gamma-rays of hadronic origin from AGN jets

abstract:
  We discuss the fluxes of high energy neutrinos and gamma-rays expected from
AGNs if hadrons can be effectively accelerated to ultra-high energies by their
relativistic jets, as currently believed. Fluxes of multi-TeV neutrinos
detectable by $km$-scale detectors like IceCube could be expected from powerful
blazars where strong accretion-disk radiation is present in the AGN cores.
Gamma-ray fluxes of hadronic origin can be important for flares in the compact
jets of these sources up to GeV energies, but they will be insignificant for BL
Lac objects. Production of UHE neutral beams composed of neutrons and
gamma-rays can drive straight collimated jets in the intergalactic medium on
multi-kpc scales, which could be resolved by the Chandra X-ray observatory.
While we do not expect any significant neutrino flux from these large-scale
jets, we predict gamma-rays of synchrotron origin in the energy range from
sub-GeV up to TeV energies, which would be detectable by GLAST and ground-based
gamma-ray telescopes.


title: Synchrotron vs Compton Interpretations for Extended X-ray Jets

abstract:
  A widely discussed explanation for the origin of the X-ray emission observed
from knots in extended quasar jets with the Chandra X-ray Obseratory is
Compton-scattered CMBR by electrons with Lorentz factors $\gamma^\prime \sim
10^2$. This model faces difficulties in terms of total energy requirements, and
in explaining the spatial profiles of the radio, optical, and X-ray knots in
sources such as PKS 0637-752, 3C 273, or PKS 1127-145. These difficulties can
be resolved in the framework of one- and two-component synchrotron models. We
propose a model where the broad band radio to X-ray synchrotron emission in
quasar jets is powered by collimated beams of ultra-high energy neutrons and
gamma-rays formed in the sub-parsec scale jets. The decay of the neutral beam
in the intergalactic medium drives relativistic shocks to accelerate nonthermal
electrons out of the ambient medium. A second synchrotron component arises from
the injection of leptons with Lorentz factors $\gg 10^7$ that appear in the
extended jet in the process of decay of ultra-high energy gamma rays. This
approach could account for qualitative differences in the extended X-ray jets
of FR1 and FR2 galaxies. Detection of high-energy neutrinos from blazars and
core-dominated quasars will provide strong evidence for this model.


title: A Lyman-alpha-only AGN from the Sloan Digital Sky Survey

abstract:
  The Sloan Digital Sky Survey has discovered a z=2.4917 radio-loud active
galactic nucleus (AGN) with a luminous, variable, low-polarization UV
continuum, H I two-photon emission, and a moderately broad Lyman-alpha line
(FWHM = 1430 km/s) but without obvious metal-line emission. SDSS
J113658.36+024220.1 does have associated metal-line absorption in three
distinct, narrow systems spanning a velocity range of 2710 km/s. Despite
certain spectral similarities, SDSS J1136+0242 is not a Lyman-break galaxy.
Instead, the Ly-alpha and two-photon emission can be attributed to an extended,
low-metallicity narrow-line region. The unpolarized continuum argues that we
see SDSS J1136+0242 very close to the axis of any ionization cone present. We
can conceive of two plausible explanations for why we see a strong UV continuum
but no broad-line emission in this `face-on radio galaxy' model for SDSS
J1136+0242: the continuum could be relativistically beamed synchrotron emission
which swamps the broad-line emission; or, more likely, SDSS J1136+0242 could be
similar to PG 1407+265, a quasar in which for some unknown reason the
high-ionization emission lines are very broad, very weak, and highly
blueshifted.


title:
M/L, H-alpha Rotation Curves, and HI Measurements for 329 Nearby Cluster
  and Field Spirals: I. Data

abstract:
  A survey of 329 nearby galaxies (redshift z < 0.045) has been conducted to
study the distribution of mass and light within spiral galaxies over a range of
environments. The 18 observed clusters and groups span a range of richness,
density, and X-ray temperature, and are supplemented by a set of 30 isolated
field galaxies. Optical spectroscopy taken with the 200-inch Hale Telescope
provides separately resolved H-alpha and [NII] major axis rotation curves for
the complete set of galaxies, which are analyzed to yield velocity widths and
profile shapes, extents and gradients. HI line profiles provide an independent
velocity width measurement and a measure of HI gas mass and distribution.
I-band images are used to deconvolve profiles into disk and bulge components,
to determine global luminosities and ellipticities, and to check morphological
classification. These data are combined to form a unified data set ideal for
the study of the effects of environment upon galaxy evolution.


title:
M/L, H-alpha Rotation Curves, and HI Measurements for 329 Nearby Cluster
  and Field Spirals: II. Evidence for Galaxy Infall

abstract:
  We have conducted a study of optical and HI properties of spiral galaxies
(size, luminosity, H-alpha flux distribution, circular velocity, HI gas mass)
to explore the role of gas stripping as a driver of morphological evolution in
clusters. We find a strong correlation between the spiral and S0 fractions
within clusters, and the spiral fraction scales tightly with cluster X-ray gas
luminosity. We explore young star formation and identify spirals that are (1)
asymmetric, with truncated H-alpha emission and HI gas reservoirs on the
leading edge of the disk, on a first pass through the dense intracluster medium
in the cores of rich clusters; (2) strongly HI deficient and stripped, with
star formation confined to the inner 5 kpc/h and 3 disk scale lengths; (3)
reddened, extremely HI deficient and quenched, where star formation has been
halted across the entire disk. We propose that these spirals are in successive
stages of morphological transformation, between infalling field spirals and
cluster S0s, and that the process which acts to remove the HI gas reservoir
suppresses new star formation on a similarly fast timescale. These data suggest
that gas stripping plays a significant role in morphological transformation and
rapid truncation of star formation across the disk.


title:
M/L, H-alpha Rotation Curves, and HI Measurements for 329 Nearby Cluster
  and Field Spirals: III. Evolutionin Fundamental Galaxy Parameters

abstract:
  We have conducted a study of optical and HI properties of spiral galaxies
(size, luminosity, H-alpha flux distribution, circular velocity, HI gas mass)
to investigate causes (e.g., nature versus nurture) for variation within the
cluster environment. We find HI deficient cluster galaxies to be offset in
Fundamental Plane space, with disk scale lengths decreased by a factor of 25%.
This may be a relic of early galaxy formation, caused by the disk coalescing
out of a smaller, denser halo (e.g., higher concentration index) or by
truncation of the hot gas envelope due to the enhanced local density of
neighbors, though we cannot completely rule out the effect of the gas stripping
process. The spatial extent of H-alpha flux and the B-band radius also
decreases, but only in early type spirals, suggesting that gas removal is less
efficient within steeper potential wells (or that stripped late type spirals
are quickly rendered unrecognizable). We find no significant trend in stellar
mass-to-light ratios or circular velocities with HI gas content, morphological
type, or clustercentric radius, for star forming spiral galaxies throughout the
clusters. These data support the findings of a companion paper that gas
stripping promotes a rapid truncation of star formation across the disk, and
could be interpreted as weak support for dark matter domination over baryons in
the inner regions of spiral galaxies.


title:
The 2dF Galaxy Redshift Survey: The blue galaxy fraction and
  implications for the Butcher-Oemler effect

abstract:
  We derive the fraction of blue galaxies in a sample of clusters at z < 0.11
and the general field at the same redshift. The value of the blue fraction is
observed to depend on the luminosity limit adopted, cluster-centric radius and,
more generally, local galaxy density, but it does not depend on cluster
properties. Changes in the blue fraction are due to variations in the relative
proportions of red and blue galaxies but the star formation rate for these two
galaxy groups remains unchanged. Our results are most consistent with a model
where the star formation rate declines rapidly and the blue galaxies tend to be
dwarfs and do not favour mechanisms where the Butcher-Oemler effect is caused
by processes specific to the cluster environment.


title:
A Far-UV Spectroscopic Analysis of the Central Star of the Planetary
  Nebula Longmore 1

abstract:
  We have performed a non-LTE spectroscopic analysis using far-UV and UV data
of the central star of the planetary nebula K1-26 (Longmore 1), and found Teff
= 120+/-10 kK, logg = 6.7 +0.3/-0.7, and y = 0.10. The temperature is
significantly hotter than previous results based on optical line analyses,
highlighting the importance of analyzing the spectra of such hot objects at
shorter wavelengths. The spectra show metal lines (from, e.g, carbon, oxygen,
sulfur, and iron). The signatures of most elements can be fit adequately using
solar abundances, confirming the classification of Longmore 1 as a high gravity
O(H) object. Adopting a distance of 800 pc, we derive R = 0.04 Rsun, L = 250
Lsun, and M = 0.6 Msun. This places the object on the white dwarf cooling
sequence of the evolutionary tracks with an age of ~= 65 kyr.


title: Using Notch-Filter Masks for High Contrast Imaging of Extrasolar Planets

abstract:
  We present the first laboratory experiments using a notch-filter mask, a
coronagraphic image mask that can produce infinite dynamic range in an ideal
Lyot coronagraph according to scalar diffraction theory. We fabricated the
first notch-filter mask prototype with .25 $\micron$ precision using an e-beam
lithography machine. Our initial optical tests show that the prototype masks
generate contrast levels of 10$^{-5}$ at 3$\lambda/D$ and 10$^{-6}$ at $\sim
8\lambda/D$, with a throughput of 27%. We speculate on the ``as-is''
performance of such a mask in the Hubble Space Telescope.


title: Destruction of Stellar Disks by Photoevaporation

abstract:
  Photoevaporation may provide an explanation for the short lifetimes of disks
around young stars. With the exception of neutral oxygen lines, the observed
low-velocity forbidden line emission from T Tauri stars can be reproduced by
photoevaporating models. The natural formation of a gap in the disk at several
AU due to photoevaporation and viscous spreading provides a possible halting
mechanism for migrating planets and an explanation for the abundance of
observed planets at these radii.


title: Search for cosmic-ray point sources with KASCADE

abstract:
  A survey of the northern hemisphere for astrophysical point sources with
continuous emission of high-energy cosmic rays is presented. Around 47 Mio
extensive air showers with primary energies above $\approx$ 300 TeV measured by
the KASCADE detector field are selected for this analysis. Besides the sky
survey, a search for signal excess in the region of the galactic plane and of
selected point source candidates has been performed. There is no evidence for
any significant excess. This is valid for an analysis of all recorded showers
as well as for a data set enhanced in gamma-ray induced showers. An upper flux
limit of around $3\times 10^{-10}$ m$^{-2}$s$^{-1}$ for a steady point source
that transits the zenith is obtained. Additionally, the distribution of the
arrival directions of extensive air showers with energies above 80 PeV were
studied by an autocorrelation analysis.


title: Strong Gravitational Lensing and Dynamical Dark Energy

abstract:
  We study the strong gravitational lensing properties of galaxy clusters
obtained from N-body simulations with different kind of Dark Energy (DE). We
consider both dynamical DE, due to a scalar field self--interacting through
Ratra-Peebles (RP) or SUGRA potentials, and DE with constant negative w=p/rho=
-1 (LCDM). We have 12 high resolution lensing systems for each cosmological
model with a mass greater than 5x10^{14} solar masses. Using a Ray Shooting
technique we make a detailed analysis of the lensing properties of these
clusters with particular attention to the number of arcs and their properties
(magnification, length and width). We found that the number of giant arcs
produced by galaxy clusters changes in a considerable way from LCDM models to
Dynamical Dark Energy models with a RP or SUGRA potentials. These differences
originate from the different epochs of cluster formation and from the
non-linearity of the strong lensing effect. We suggest the Strong lensing is
one of the best tool to discriminate among different kind of Dark Energy.


title:
Multiple-Images in the Cluster Lens Abell 2218: Constraining the
  Geometry of the Universe ?

abstract:
  In this Letter we present a detailed study of the lensing configuration in
the cluster Abell 2218. Four multiple-images systems with measured
spectroscopic redshifts have been identified in this cluster. These multiple
images are very useful to constrain accurately the mass distribution in the
cluster core, but they are also sensitive to the value of the geometrical
cosmological parameters of the Universe. Using a simplified maximum likelihood
analysis we find 0 < Omega_M < 0.30 assuming a flat Universe, and 0 < Omega_M <
0.33 and w < -0.85 for a flat Universe with dark energy. Interestingly, an
Einstein-de Sitter model is excluded at more than 4sigma. These constraints are
consistent with the current constraints derived with CMB anisotropies or
supernovae studies. The proposed method constitutes an independent test of the
geometrical cosmological parameters of the Universe and we discuss the limits
of this method and this particular application to Abell 2218. Application of
this method with more sophisticated tools and to a larger number of clusters or
with more multiple images constraints, will put stringent constraints on the
geometrical cosmological parameters.


title: 1E 1207.4-5209: a low-mass bare strange star?

abstract:
  Both rotation- and accretion-powered low-mass bare strange stars are studied,
the astrophysical appearances of which are especially focused. It is suggested
that low-mass bare strange stars, with weaker ferromagnetic fields than that of
normal pulsars, could result from accretion-induced collapses (AIC) of white
dwarfs. According to its peculiar timing behavior, we propose that the
radio-quiet object, 1E 1207.4-5209, could be a low-mass bare strange star with
polar surface magnetic field ~ 6 x 10^10 G and a few kilometers in radius. The
low-mass bare strange star idea is helpful to distinguish neutron and strange
stars, and is testable by imaging pulsar-like stars with the future
Constellation-X telescope.


title:
An XMM-Newton observation of Ark 120: the X-ray spectrum of a `bare'
  Seyfert 1 nucleus

abstract:
  We report on a long (100 ks) XMM-Newton observation of the bright Seyfert 1
galaxy Arakelian 120. The source previously showed no signs of intrinsic
reddening in its infrared-ultraviolet continuum and previous observations had
shown no evidence for ionized absorption in either the ultraviolet or X-ray
bands. The new XMM-Newton RGS data place tight limits on the presence of an
ionized X-ray absorber and confirm that the X-ray spectrum of Ark 120 is
essentially unmodified by intervening matter. Thus Ark 120 can be considered a
`bare' Seyfert 1 nucleus. This observation therefore offers a clean view of the
X-ray spectrum of a `normal' Seyfert galaxy free from absorption effects. The
spectrum shows a Doppler broadened iron emission line (FWHM ~ 3*10^4 km/s) and
a smooth, continuous soft excess which appears to peak at an energy ~0.5 keV.
This adds weight to the claim that genuine soft excesses (i.e. those due to a
real steepening of the underlying continuum below ~2 keV) are ubiquitous in
Seyfert 1 spectra. However, the detailed shape of the excess could not be
reproduced by any of the simple models tested (power-laws, blackbodies,
Comptonised blackbodies, accretion disc reflection). This observation therefore
demonstrates both the need to understand the soft excess (as a significant
contributor to the luminosity of most Seyfert 1s) and the inability of the
existing, simple models to explain it.


title:
Scattering of gravitational radiation: second order moments of the wave
  amplitude

abstract:
  Gravitational radiation that propagates through an inhomogeneous mass
distribution is subject to random gravitational lensing, or scattering, causing
variations in the wave amplitude and temporal smearing of the signal. A
statistical theory is constructed to treat these effects. The statistical
properties of the wave amplitude variations are a direct probe of the power
spectrum of the mass distribution through which the waves propagate. Scattering
temporally smears any intensity variations intrinsic to a source emitting
gravitational radiation, rendering variability on time scales shorter than the
temporal smearing time scale unobservable, and potentially making the radiation
much harder to detect. Gravitational radiation must propagate out through the
mass distribution of its host galaxy before it can be detected at the Earth.
Plausible models for the distribution of matter in an $L_*$ host galaxy suggest
that the temporal smearing time scale is at least several milliseconds due to
the gas content alone, and may be as large as a second if dark matter also
scatters the radiation. The smearing time due to scattering by any galaxy
interposed along the line of sight is a factor $\sim 10^5$ times larger.
Gravitational scattering is an excellent probe of matter on parsec and
sub-parsec scales, and has the potential to elucidate the nature of dark
matter.


title:
Amplification of Galactic Magnetic Fields by the Cosmic-Ray Driven
  Dynamo

abstract:
  We present the first numerical model of the magnetohydrodynamical cosmic-ray
(CR) driven dynamo of the type proposed by Parker (1992). The driving force of
the amplification process comes from CRs injected into the galactic disk in
randomly distributed spherical regions representing supernova remnants. The
underlying disk is differentially rotating. An explicit resistivity is
responsible for the dissipation of the small-scale magnetic field component. We
obtain amplification of the large-scale magnetic on a timescale 250 Myr.


title: An XMM-Newton observation of the massive binary HD159176

abstract:
  We report the analysis of an XMM-Newton observation of the close binary
HD159176 (O7V + O7V). The observed L_X/L_bol ratio reveals an X-ray luminosity
exceeding by a factor ~ 7 the expected value for X-ray emission from single
O-stars, therefore suggesting a wind-wind interaction scenario. EPIC and RGS
spectra are fitted consistently with a two temperature mekal optically thin
thermal plasma model, with temperatures ranging from ~ 2 to 6 10^6 K. At first
sight, these rather low temperatures are consistent with the expectations for a
close binary system where the winds collide well before reaching their terminal
velocities. We also investigate the variability of the X-ray light curve of
HD159176 on various short time scales. No significant variability is found and
we conclude that if hydrodynamical instabilities exist in the wind interaction
region of HD159176, they are not sufficient to produce an observable signature
in the X-ray emission. Hydrodynamic simulations using wind parameters from the
literature reveal some puzzling discrepancies. The most striking one concerns
the predicted X-ray luminosity which is one or more orders of magnitude larger
than the observed one. A significant reduction of the mass loss rate of the
components compared to the values quoted in the literature alleviates the
discrepancy but is not sufficient to fully account for the observed luminosity.
Because hydrodynamical models are best for the adiabatic case whereas the
colliding winds in HD159176 are most likely highly radiative, a totally new
approach has been envisaged... (see paper for complete abstract)


title:
Statistical properties of exoplanets III. Planet properties and stellar
  multiplicity

abstract:
  Among the hundred or so extrasolar planets discovered to date, 19 are
orbiting a component of a double or multiple star system. In this paper, we
discuss the properties of these planets and compare them to the characteristics
of planets orbiting isolated stars. Although the sample of planets found in
multiple star systems is not large, some differences between the orbital
parameters and the masses of these planets and the ones of planets orbiting
single stars are emerging in the mass-period and in the eccentricity-period
diagrams. As pointed out by Zucker & Mazeh (2002), the most massive
short-period planets are all found in multiple star systems. We show here that
the planets orbiting in multiple star systems also tend to have a very low
eccentricity when their period is shorter than about 40 days. These
observations seem to indicate that some kind of migration has been at work in
the history of these systems. The properties of the five short-period planets
orbiting in multiple star systems seem, however, difficult to explain with the
current models of planet formation and evolution, at least if we want to invoke
a single mechanism to account for all the characteristics of these planets.


title:
General Relativistic Magnetohydrodynamic Simulations of Black Hole
  Accretion Disks

abstract:
  Observations are providing increasingly detailed quantitative information
about the accretion flows that power such high energy systems as X-ray binaries
and active galactic nuclei. Analytic models of such systems must rely on
assumptions such as regular flow geometry and a simple, parameterized stress.
Global numerical simulations offer a way to investigate the basic physical
dynamics of accretion flows without these assumptions. For black hole accretion
studies one solves the equations of general relativistic magnetohydrodynamics.
Magnetic fields are of fundamental importance to the structure and evolution of
accretion disks because magnetic turbulence is the source of the anomalous
stress that drives accretion. We have developed a three-dimensional general
relativistic magnetohydrodynamic simulation code to evolve time-dependent
accretion systems self-consistently. Recent global simulations of black hole
accretion disks suggest that the generic structure of the accretion flow is
usefully divided into five regimes: the main disk, the inner disk, the corona,
the evacuated funnel, and the funnel wall jet. The properties of each of these
regions are summarized.


title:
Polarimetric Pulse Profile Modeling: Applications to High-Precision
  Timing and Instrumental Calibration

abstract:
  A new method is presented for modeling the transformation between two
polarimetric pulse profiles in the Fourier domain. In practice, one is a
well-determined standard with high signal-to-noise ratio and the other is an
observation that is to be fitted to the standard. From this fit, both the
longitudinal shift and the polarimetric transformation between the two profiles
are determined. Arrival time estimates derived from the best-fit longitudinal
shift are shown to exhibit greater precision than those derived from the total
intensity profile alone. In addition, the polarimetric transformation obtained
through this method may be used to completely calibrate the instrumental
response in observations of other sources.


title:
General Relativistic Magnetohydrodynamic Simulations of Black Hole
  Accretion Disks: Results and Observational Implications

abstract:
  A selection of results from the general relativistic MHD accretion
simulations described in the previous talk are presented. We find that the
magnetic field strength increases sharply with decreasing radius and is also
enhanced near rapidly-spinning black holes. The greater magnetic field strength
associated with rapid black hole rotation leads to a large outward
electromagnetic angular momentum flux that substantially reduces both the mean
accretion rate and the net accreted angular momentum per unit rest-mass. This
electromagnetic stress strongly violates the traditional guess that the
accretion stress vanishes at and inside the marginally stable orbit. Possible
observational consequences include a constraint on the maximum spin of black
holes, enhancement to the radiative efficiency, and concentration of
fluorescent Fe Kalpha to the innermost part of the accretion disk.


title: Cross section predictions for hydrostatic and explosive burning

abstract:
  We review different models used for reactions involved in nuclear
astrophysics. The reaction rate is defined for resonant as well as for
non-resonant processes. For low-density nuclei, we describe the DWBA method,
the potential model, the R-matrix method, and microscopic cluster models. The
statistical model is developed for high-level densities. Details of
calculations in the low- and high-density regimes are illustrated with new
results concerning transfer reactions and level densities.


title: Magnetic Sunyaev-Zel'dovich effect in galaxy clusters

abstract:
  This Letter explores influences of intracluster magnetic fields ($\gsim
1\mu$G) submerged in the hot electron gas on classic Sunyaev-Zel'dovich effect
(SZE) and thermal bremsstrahlung in X-ray emissions. As the Larmor frequency is
much higher than all collision frequencies, the presence of magnetic field may
lead to an anisotropic velocity distribution of hot electrons. For the
two-temperature relativistic Maxwell-Boltzmann distribution, we compute
modifications to the classical thermal SZE. Intracluster magnetic fields tend
to enhance the SZE with steeper radial variations, which bear important
consequences for cluster-based estimates of cosmological parameters. By
applying the magnetic SZE theory to spectral observations of SZ and Chandra
X-ray emissions from the galaxy cluster Abell 2163, a $\sim 30-40\mu$G central
core magnetic field $B_0$ is predicted. For the SZ and Chandra X-ray spectral
observations of the Coma cluster, our theoretical analysis is also consistent
with an observationally inferred $B_0\lsim 10\mu$G. As the magnetic SZE is
redshift $z$ independent, this mechanism might offer a potentially important
and unique way of probing intracluster magnetic fields in the expanding
universe.


title: The effect of starspots on eclipse timings of binary stars

abstract:
  We investigate the effects that starspots have on the light curves of
eclipsing binaries and in particular how they may affect the accurate
measurement of eclipse timings. Concentrating on systems containing a low-mass
main-sequence star and a white dwarf, we find that if starspots exhibit the
Wilson depression they can alter the times of primary eclipse ingress and
egress by several seconds for typical binary parameters and starspot
depressions. In addition, we find that the effect on the eclipse ingress/egress
times becomes more profound for lower orbital inclinations. We show how it is
possible, in principle, to determine estimates of both the binary inclination
and depth of the Wilson depression from light curve analysis
  The effect of depressed starspots on the O-C diagrams of eclipsing systems is
also investigated. It is found that the presence of starspots will introduce a
`jitter' in the O-C residuals and can cause spurious orbital period changes to
be observed. Despite this, we show that the period can still be accurately
determined even for heavily spotted systems.


title: Stellar radio astrophysics

abstract:
  Radio emission has been detected from all the stages of stellar evolution
across the HR Diagram. Its presence reveals both astrophysical phenomena and
stellar activity which, otherwise, would not be detectable by other means. The
development of large, sensitive interferometers has allowed us to resolve the
radio structure of several stellar systems, providing insights into the mass
transfer process in close binary systems. I review the main characteristics of
the radio emission from several kinds of stars, paying special attention to
those cases where such an emission originates in relativistic jets.


title:
Chandra observation of an unusually long and intense X-ray flare from a
  young solar-like star in M78

abstract:
  LkHA312 has been observed serendipitously with the ACIS-I detector on board
Chandra with 26h continuous exposure. This H_alpha emission line star belongs
to the star-forming region M78 (NGC2068). From the optical and NIR data, we
show that it is a pre-main sequence (PMS) low-mass star with a weak NIR excess.
This genuine T Tauri star displayed an X-ray flare with an unusual long rise
phase (~8h). The X-ray emission was nearly constant during the first 18h of the
observation, and then increased by a factor of 13 during a fast rise phase
(~2h), and reached a factor of 16 above the quiescent X-ray level at the end of
a gradual phase (~6h) showing a slower rise. To our knowledge this flare, with
\~0.4-~0.5 cts/s, has the highest count rate observed so far with Chandra from
a PMS low-mass star. By chance, the source position, 8.2' off-axis, protected
this observation from pile-up. We make a spectral analysis of the X-ray
emission versus time, showing that the plasma temperature of the quiescent
phase and the flare peak reaches 29MK and 88MK, respectively. The quiescent and
flare luminosities in the energy range 0.5--8keV corrected from absorption
(N_H~1.7E21 cm^{-2}) are 6E30erg/s and ~1E32erg/s, respectively. The ratio of
the quiescent X-ray luminosity on the LkHA312 bolometric luminosity is very
high with log(L_X/L_bol)= -2.9, implying that the corona of LkHA312 reached the
`saturation' level. The X-ray luminosity of the flare peak reaches ~2% of the
stellar bolometric luminosity. The different phases of this flare are finally
discussed in the framework of solar flares, which leads to the magnetic loop
height from 3.1E10 to 1E11 cm (0.2-0.5 R*, i.e., 0.5-1.3 R_sun).


title: The Relation between Interstellar Turbulence and Star Formation

abstract:
  (ABBREVIATED) Understanding the formation of stars in galaxies is central to
much of modern astrophysics. In this review the relation between interstellar
turbulence and star formation is discussed. Supersonic turbulence can provide
support against gravitational collapse on global scales, while at the same time
it produces localized density enhancements that allow for collapse on small
scales. The efficiency and timescale of stellar birth in Galactic gas clouds
strongly depend on the properties of the interstellar turbulent velocity field,
with slow, inefficient, isolated star formation being a hallmark of turbulent
support, and fast, efficient, clustered star formation occurring in its
absence. Star formation on scales of galaxies as a whole is expected to be
controlled by the balance between gravity andturbulence, just like star
formation on scales of individual interstellar gas clouds, but may be modulated
by additional effects like cooling and differential rotation. The dominant
mechanism for driving interstellar turbulence in star-forming regions of
galactic disks appears to be supernovae explosions. In the outer disk of our
Milky Way or in low-surface brightness galaxies the coupling of rotation to the
gas through magnetic fields or gravity may become important.


title:
Jet-disc coupling through a common energy reservoir in the black hole
  XTE J1118+480

abstract:
  We interpret the rapid correlated UV/optical/ X-ray variability of XTE
J1118+480 as a signature of the coupling between the X-ray corona and a jet
emitting synchrotron radiation in the optical band. We propose a scenario in
which the jet and the X-ray corona are fed by the same energy reservoir where
large amounts of accretion power are stored before being channelled into either
the jet or the high energy radiation. This time dependent model reproduces the
main features of the rapid multi-wavelength variability of XTE J1118+480.
Assuming that the energy is stored in the form of magnetic field, we find that
the required values of the model parameters are compatible with both a patchy
corona atop a cold accretion disc and a hot thick inner disc geometry. The
range of variability timescales for the X-ray emitting plasma are consistent
with the dynamical times of an accretion flow between 10 and 100 Schwarzschild
radii. On the other hand, the derived range of timescales associated with the
dissipation in the jet extends to timescales more than 10 times larger,
confirming the suggestion that the generation of a powerful outflow requires
large scale coherent poloidal field structures. A strong requirement of the
model is that the total jet power should be at least a few times larger than
the observed X-ray luminosity. This would be consistent with the overall low
radiative efficiency of the source. We present independent arguments showing
that the jet probably dominates the energetic output of all accreting black
holes in the low-hard state.


title: Generating Hot Gas in Simulations of Disk-Galaxy Major Mergers

abstract:
  We report on the merger-induced generation of a shock-heated gas wind and
formation of a remnant gas halo in simulations of colliding disk galaxies. The
simulations use cosmologically motivated initial conditions and include the
effects of radiative cooling, star formation, stellar feedback and the
non-adiabatic heating of gas. The non-adiabatic heating, i.e. shocks, generated
in the final merger forces gas out of the central region of the merger remnant
and into the dark-matter halo. We demonstrate that the amount of heating
depends on the size of the progenitor disk galaxy as well as the initial orbit
the galaxies are placed on. Based upon these dependencies, we motivate a
possible recipe for including this effect in semi-analytic models of galaxy
formation.


title: The Spectral Energy Distributions of Narrow-line Seyfert 1 Galaxies

abstract:
  Narrow-line Seyfert 1 galaxies are identified by their uniform optical
spectral properties. Studies of samples of NLS1s reveal, however, a range of
X-ray spectral and variability behavior, and UV spectral behavior. We describe
the range of behavior observed, illustrating with a comparison of the
XMM-Newton and HST data from the NLS1s 1H0707-495 and TonS180, and discuss how
the spectral energy distribution may causally link the UV and X-ray properties.


title:
Observational Evidence for Intermediate-Mass Black Holes in
  Ultra-luminous X-ray Sources

abstract:
  Evidence is mounting that some Ultra-luminous X-ray sources (ULXs) may
contain accreting intermediate-mass black holes (IMBHs). We review the current
observational evidence for IMBH-ULXs. While low-luminosity ULXs with L_X <~
10^39.5 erg/s (assuming isotropic emission) are consistent with mildly X-ray
beamed high-mass X-ray binaries, there are a considerable number of ULXs with
larger X-ray luminosities that are not easily explained by these models. Recent
high-S/N XMM X-ray spectra are showing an increasing number of ULXs with ``cool
disks'' -- accretion disks with multi-color blackbody inner disk temperatures
kT_in ~ 0.1-0.2 keV, consistent with accreting IMBHs. Optical emission-line
studies of ULX nebulae provide useful measurements of X-ray energetics, and can
thus determine if the X-rays are emitted isotropically. Analysis of an optical
spectrum of the Ho II ULX nebulae implies an X-ray energy source with ~10^40
erg/s is present, suggesting an isotropically-emitting IMBH. The spatial
coincidence of ULXs with dense star clusters (young clusters and globular
clusters) suggests that IMBHs formed in these clusters could be the compact
objects in the associated ULXs. Quasi-periodic oscillations and frequency
breaks in XMM power-density spectra of ULXs also suggest that the black hole
masses are more consistent with IMBHs than stellar-mass black holes. Since
_all_ of these ULXs with evidence for IMBHs are high-luminosity ULXs, i.e., L_X
>~ 10^40 ergs, we suggest that this class of ULXs is generally powered by
accreting IMBHs.


title:
The Observed and Predicted Spatial Distribution of Milky Way Satellite
  Galaxies

abstract:
  We review evidence that the census of Milky Way satellites similar to those
known may be incomplete at low latitude due to obscuration and in the outer
halo due to a decreasing sensitivity to dwarf satellites with distance. We
evaluate the possible impact that incompleteness has on comparisons with
substructure models by estimating corrections to the known number of dwarfs
using empirical and theoretical models. If we assume that the true distribution
of Milky Way satellites is uniform with latitude, then we estimate a 33%
incompleteness in the total number of dwarfs due to obscuration at low
latitude. Similarly, if we suppose that the radial distribution of Milky Way
satellites matches that of M31, or that of the oldest sub-halos or the most
massive sub-halos in a simulation, we estimate a total number of Milky Way
dwarfs ranging from 1 -- 3 times the known population. Although the true level
of incompleteness is quite uncertain, the fact that our extrapolations yield
average total numbers of MW dwarfs that are realistically 1.5 -- 2 times the
known population, shows that incompleteness needs to be taken seriously when
comparing to models of dwarf galaxy formation. Interestingly, the radial
distribution of the oldest sub-halos in a Lambda+CDM simulation of a Milky
Way-like galaxy possess a close match to the observed distribution of M31's
satellites, which suggests that reionization may be an important factor
controlling the observability of sub-halos. We also assess the prospects for a
new SDSS search for Milky Way satellites to constrain the possible
incompleteness in the outer halo.


title: Occultations of HIP and UCAC2 stars downto 15m by large TNO in 2004-2014

abstract:
  Occultations of stars brighter than 15m by largest TNOs are predicted. Search
was performed using the following catalogues: Hipparcos; Tycho2 with
coordinates of 2838666 stars taken from UCAC2 (Herald, 2003); UCAC2 (Zacharias
et al., 2003) with 16356096 stars between 12.00 and 14.99 mag to the north from
-45 declination. Predictions were made for 17 largest numbered transneptunian
asteroids, recently discovered 2004 DW and 4 known binary Kuiper Belt objects.
64 events occuring at solar elongation of 30 deg and more are selected,
including exceptionally rare occultation of 6.5m star by double (66652) 1999
RZ253 on 2007 October 4th. Observations of these events by all available means
are extremely important since they can provide unique information about the
size of TNOs and improve their orbits dramatically.


title: Expansion, Geometry, and Gravity

abstract:
  In general-relativistic cosmological models, the expansion history, matter
content, and geometry are closely intertwined. In this brief paper, we clarify
the distinction between the effects of geometry and expansion history on the
luminosity distance. We show that the cubic correction to the Hubble law,
measured recently with high-redshift supernovae, is the first cosmological
measurement, apart from the cosmic microwave background, that probes directly
the effects of spatial curvature. We illustrate the distinction between
geometry and expansion with a toy model for which the supernova results already
indicate a curvature radius larger than the Hubble distance.


title:
Symbiotic Stars as Laboratories for the Study of Accretion and Jets: A
  Call for Optical Monitoring

abstract:
  Symbiotic binary stars typically consist of a white dwarf (WD) that accretes
material from the wind of a companion red giant. Orbital periods for these
binaries are on the order of years, and their relatively small optical
outbursts tend to occur every few years to decades. In some symbiotics,
material that is transferred from the red giant to the WD forms a disk around
the WD. Thus, symbiotic stars are a bit like overgrown cataclysmic variables
(CVs), but with less violent eruptions. Symbiotic stars are not as well
understood as CVs, in part because their longer variability time scales mean
that observations over many years are required to cover different outburst
states and orbital phases. The recent discovery of collimated outflows ("jets")
from a number of symbiotics, provides a new motivation for such long-term study
of these objects. Astrophysical jets are observed in almost every type of
accretion-powered system, and symbiotic stars may help us understand these
structures. In symbiotics, most jets appear to be associated with optical
eruptions. Optical monitoring by amateurs can identify systems in outburst, and
also help to build a comprehensive database of outburst and quiescent symbiotic
light curves. Together with radio through X-ray observations that will be
performed when new outbursts are found, long-term optical light curves will
improve understanding of symbiotic outbursts, jet production, and the
connection between outbursts, jets, and accretion disks in symbiotic stars.


title: The Evolution of Galaxies: A Metaphysics Viewpoint

abstract:
  This is the written version of an invited review talk for the 13 Feb 2004
AAAS Meeting in Seattle. The talk's goal is to present a philosophical view of
extragalactic astronomy as it applies to the sub-field of galaxy evolution. The
talk is divided into three parts: 1) How we got to where we are (technology
drivers to our science goals), 2) What's new and special (how that technology
has achieved our recent science results) and 3) How an improved worldview will
help us in the near future. The intended audience for this talk is a generally
knowledgeable scientist, but not an astronomer by training. This talk is also
not intended to be a complete review of the field of galaxy evolution and only
includes a few recent results extracted from the astro-ph archives to present
the current state of our field.


title: Sensitivity of quintessence perturbations to initial conditions

abstract:
  Gauge invariant quintessence perturbations in the quintessence and cold dark
matter (QCDM) model are investigated. For three cases of constant
equation-of-state (EOS) parameter, linear scalar field potential, and
supergravity scalar field potential, their perturbation evolutions have a
similar dependence on EOS parameter and scale, but they have different
sensitivity to the initial conditions due to the different shapes of the
quintessence potential. They have a minor effect on primary CMB anisotropies,
but change the secondary CMB effect in different ways. The first case is
insensitive to initial quintessence perturbations and only modifies the
Integrated Sachs-Wolfe (ISW) effect within a factor of 2. The other two cases
are sensitive to initial conditions at large scales and could affect the
secondary CMB anisotropies drastically depending on how smooth the initial
perturbations are. This makes it possible for future cosmological probes to
provide constraints on quintessence properties.


title:
Stochastic Acceleration of 3He and 4He by Parallel Propagating Plasma
  Waves

abstract:
  Stochastic acceleration of $^3$He and $^4$He from a thermal background by
parallel propagating turbulent plasma waves with a single power-law spectrum of
the wavenumber is studied. In the model, both ions interact with several
resonant modes. When one of these modes dominates, the acceleration rate is
reduced considerably. At low energies, this happens for $^4$He, but not for
$^3$He where contributions from the two stronger modes are comparable so that
acceleration of $^3$He is very efficient. As a result, the acceleration of
$^4$He is suppressed by a barrier below $\sim 100$ keV nucleon$^{-1}$ and there
is a prominent quasi-thermal component in the $^4$He spectra, while almost all
the injected $^3$He ions are accelerated to high energies. This accounts for
the large enrichment of $^3$He at high energies observed in impulsive solar
energetic particle events. With reasonable plasma parameters this also provides
a good fit to the spectra of both ions. Beyond $\sim 1$ MeV nucleon$^{-1}$, the
spectrum of $^3$He is softer than that of $^4$He, which is consistent with the
observed decrease of the $^3$He to $^4$He ratio with energy. This study also
indicates that the acceleration, Coulomb losses and diffusive escape of the
particles from the acceleration site {\it all} play important roles in shaping
the ion spectra. This can explain the varied spectral shapes observed recently
by the {\it Advanced Composition Explorer}.


title: The soft X-ray excess AGN RE J2248-511

abstract:
  We model the spectral energy distribution of the ultrasoft broad-line AGN RE
J2248-511 with Comptonised accretion disc models. These are able to reproduce
the steep optical and ultrasoft X-ray slopes, and the derived black hole mass
is consistent with independent mass estimates. This AGN displays properties of
both broad and narrow line Seyfert 1 galaxies, but we conclude that it is
intrinsically a `normal' Seyfert 1 viewed at high inclination angle.


title:
A new type of photoionized code required for the new era of X-ray
  spectroscopy

abstract:
  With the advent of the present and future spatial X-ray missions, it becomes
crucial to model correctly the line spectrum of X-ray emitting media. We have
built a photoionization code, Titan, solving the transfer of a thousand lines
and of the continuum with the "Accelerated Lambda Iteration" method, which is
most reliable for line transfer. In all other photoionization codes the line
intensities are computed with the so-called "escape probability formalism",
used in its simplest approximation. In a previous paper (Dumont et al. 2003),
it was shown that this approximation leads to errors which can exceed one order
of magnitude in the case a Thomson thickness of the order of unity. We show
here that it also happens in the case of a Thomson thickness of 0.001 to 0.1.
The errors on the line fluxes and line ratios are of the order of 30% for a
column density of 10^{20} cm^{-2}, and a factor five for a column density of
10^{23} cm^{-2}, in conditions appropriate for Seyfert 2 and for the Warm
Absorber of Seyfert 1.


title:
The effect of differential refraction on wave propagation in rotating
  pulsar magnetospheres

abstract:
  Refraction of wave propagation in a corotating pulsar magnetospheric plasma
is considered as a possible interpretation for observed asymmetric pulse
profiles with multiple components. The pulsar radio emission produced inside
the magnetosphere propagates outward through the rotating magnetosphere,
subject to refraction by the intervening plasma that is spatially
inhomogeneous. Both effects of a relativistic distribution of the plasma and
rotation on wave propagation are considered. It is shown that refraction
coupled with rotation can produce asymmetric conal structures of the profile.
The differential refraction due to the rotation can cause the conal structures
to skew toward the rotation direction and lead to asymmetry in relative
intensities between the leading and trailing components. Both of these features
are potentially observable.


title:
Neutrino Interaction with Nucleons in the Envelope of a Collapsing Star
  with a Strong Magnetic Field

abstract:
  The interaction of neutrinos with nucleons in the envelope of a remnant of
collapse with a strong magnetic field during the passage of the main neutrino
flux is investigated. General expressions are derived for the reaction rates
and for the energy-momentum transferred to the medium through the neutrino
scattering by nucleons and in the direct URCA processes. Parameters of the
medium in a strong magnetic field are calculated under the condition of
quasi-equilibrium with neutrinos. Numerical estimates are given for the
neutrino mean free paths and for the density of the force acting on the
envelope along the magnetic field. It is shown that in a strong toroidal
magnetic field, the envelope region partially transparent to neutrinos can
acquire a large angular acceleration on the passage time scales of the main
neutrino flux.


title: Observational Evidence from Supernovae for a Contracting Universe

abstract:
  New precision in measuring extragalactic distances using supernovae has
confirmed with high probability an accelerating increase in redshift with
distance. This has been interpreted as implying the existence of dark energy in
an expanding and accelerating, flat universe. A more logical explanation of
these observations follows directly from an observation made by Erwin
Schrodinger in 1939 that in a closed Friedmann universe every quantum wave
function changes with spacetime geometry. Double the size of the universe and
both the wavelengths of photons and the sizes of atoms double. When the
evolution of atoms and photons are combined, the meaning of Hubble redshift is
reversed. Redshift is characteristic of contracting universes. The
magnitude-redshift curve for a contracting universe has exactly the
accelerating form recently observed and is in excellent quantitative agreement
with the data of Riess et al. 1998, Knop et al. 2003, and others. An observed
maximum redshift of 1.3 gives a minimum age estimate for the universe of 114
billion years. The time until collapse is estimated to be 15 billion years or
less.


title:
Spectroscopic rotation velocities of L dwarfs from VLT/UVES and their
  comparison with periods from photometric monitoring

abstract:
  The variability and rotation of ultra cool dwarfs (UCDs) provide important
information on their atmospheres and evolution. As part of an ongoing program
to investigate this, projected rotation speeds, vsini, are presented for 16
field UCDs (M9V-L7.5V). This doubles the number of L dwarfs for which vsini has
been measured. All targets are found to have vsini between 10 and 40 km/s,
confirming that L dwarfs are rapid rotators. From the random distribution of
the rotation axes, i, one-sided confidence intervals are placed on the rotation
periods of individual object. These are compared with published period data
obtained from photometric monitoring. From this, the period of 31 hrs for the
L0.5 dwarf 2M0746+2000 published by Gelino et al. (2002) may be ruled out as
the rotation period. The period of 11.2 +/- 0.8 hrs for the L1.5 dwarf
2M1145+2317 obtained by Bailer-Jones & Mundt (2001) is plausibly the rotation
period. The inclination of the rotation axis is i = 62-90 deg with an
expectation value of 76 deg. Alternatively the data set a lower limit on the
radius of 0.1 Rsol. Similarly, the period of 2.7 +/- 0.1 hrs for 2M1334+1940 is
the likely rotation period; the inclination is i = 27-44 deg (mean i = 34 deg).
Where no variability or period was detected by the monitoring programs the
likely reason is low contrast surface features. However, in three cases
variability but no period was detected, despite sensitivity to the likely
rotation periods inferred from vsini. This reinforces the `masking hypothesis',
the idea that the evolution of photospheric features obscures regular
modulation of the light curve. As has been previously discussed, a likely
candidate for such features is inhomogeneous dust clouds.


title:
Hydromagnetic and gravitomagnetic crust-core coupling in a precessing
  neutron star

abstract:
  We consider two types of mechanical coupling between the crust and the core
of a precessing neutron star. First, we find that a hydromagnetic (MHD)
coupling between the crust and the core strongly modifies the star's
precessional modes when $t_a\le\sim (T_s\times T_p)^{1/2}$; here $t_a$ is the
Alfven crossing timescale, and $T_s$ and $T_p$ are the star's spin and
precession periods, respectively. We argue that in a precessing pulsar PSR
B1828-11 the restoring MHD stress prevents a free wobble of the crust relative
to the non-precessing core. Instead, the crust and the proton-electron plasma
in the core must precess in unison, and their combined ellipticity determines
the period of precession. Link has recently shown that the neutron superfluid
vortices in the core of PSR B1828-11 cannot be pinned to the plasma; he has
also argued that this lack of pinning is expected if the proton Fermi liquid in
the core is type-I superconductor. In this case, the neutron superfluid is
dynamically decoupled from the precessing motion. The pulsar's precession
decays due to the mutual friction between the neutron superfluid and the plasma
in the core. The decay is expected to occur over tens to hundreds of precession
periods and may be measurable over a human lifetime. Such a measurement would
provide information about the strong n-p interaction in the neutron-star core.
Second, we consider the effect of gravitomagnetic coupling between the neutron
superfluid in the core and the rest of the star and show that this coupling
changes the rate of precession by about 10%. The general formalism developed in
this paper may be useful for other applications.


title: On the Polarization of Gamma Ray Bursts and their Optical Afterglows

abstract:
  The polarization of the optical afterglow (AG) of Gamma-Ray Bursts (GRBs) has
only been measured in a few instances at various times after the GRB. In all
cases except the best measured one (GRB 030329) the observed polarization and
its evolution are simple and easy to explain in the most naive version of the
"Cannonball'' model of GRBs: the "intrinsic" AG polarization is small and the
observations reflect the "foreground" effects of the host galaxy and ours. The
polarization observed in GRB 030329 behaves chaotically, its understanding
requires reasonable but ad-hoc ingredients. The polarization of the gamma rays
of a GRB has only been measured in the case of GRB 021206. The result is
debated, but similar measurements would be crucial to the determination of the
GRB-generating mechanism.


title:
Markov Chain Monte Carlo joint analysis of Chandra X-ray imaging
  spectroscopy and Sunyaev-Zeldovich Effect data

abstract:
  X-ray and Sunyaev-Zeldovich Effect data can be combined to determine the
distance to galaxy clusters. High-resolution X-ray data are now available from
the Chandra Observatory, which provides both spatial and spectral information,
and Sunyaev-Zeldovich Effect data were obtained from the BIMA and OVRO arrays.
We introduce a Markov chain Monte Carlo procedure for the joint analysis of
X-ray and Sunyaev-Zeldovich Effect data. The advantages of this method are the
high computational efficiency and the ability to measure simultaneously the
probability distribution of all parameters of interest, such as the spatial and
spectral properties of the cluster gas and also for derivative quantities such
as the distance to the cluster. We demonstrate this technique by applying it to
the Chandra X-ray data and the OVRO radio data for the galaxy cluster Abell
611. Comparisons with traditional likelihood-ratio methods reveal the
robustness of the method. This method will be used in follow-up papers to
determine the distances to a large sample of galaxy clusters.


title: High Resolution X-ray Spectroscopy of the Post-T Tauri Star PZ Tel

abstract:
  We present an analysis of the Chandra High Energy Transmission Grating
Spectrometer observation of the rapidly rotating P_(rot)=0.94 d post T Tauri
(~20 Myr old) star PZ Telescopii, in the Tucana association. Using two
different methods we have derived the coronal emission measure distribution,
em(T), and chemical abundances. The em(T) peaks at log T = 6.9 and exhibits a
significant emission measure at temperatures log T > 7. The coronal abundances
are generally ~0.5 times the solar photospheric values that are presumed fairly
representative of the composition of the underlying star. A minimum in
abundance is seen at a first ionization potential (FIP) of 7-8 eV, with
evidence for higher abundances at both lower and higher FIP, similar to
patterns seen in other active stars. From an analysis of the He-like triplet of
Mg XI we have estimated electron densities of ~10^(12)-10^(13) cm^(-3). All the
coronal properties found for PZ Tel are much more similar to those of AB Dor,
which is slightly older than PZ Tel, than to those of the younger T Tauri star
TW Hya. These results support earlier conclusions that the soft X-ray emission
of TW Hya is likely dominated by accretion activity rather than by a
magnetically-heated corona. Our results also suggest that the coronae of
pre-main sequence stars rapidly become similar to those of older active
main-sequence stars soon after the accretion stage has ended.


title:
Spectral Evolution of weak bursts from SGR 1806-20 observed with
  INTEGRAL

abstract:
  We report on bursts from the Soft Gamma-Ray Repeater SGR 1806--20 detected
with INTEGRAL in October 2003, during a period of moderate activity of the
source. The spectral and temporal properties of 21 short bursts are consistent
with those found in previous observations, even if these bursts are among the
faintest observed in the 15-200 keV range from this source. During some of the
bursts a clear spectral evolution is visible. The data also show, for the first
time, evidence for a hardness-intensity anti-correlation within SGR 1806--20
bursts.


title: Skewness as a test of the equivalence principle

abstract:
  The skewness of the large scale distribution of matter has long been known to
be a probe of gravitational clustering. Here we show that the skewness is also
a probe of violation of the equivalence principle between dark matter and
baryons. The predicted level of violation can be tested with the forecoming
data from the Sloan Digital Sky Survey.


title: Two-body relaxation in modified Newtonian dynamics

abstract:
  A naive extension to MOND of the standard computation of the two-body
relaxation time Tb implies that Tb is comparable to the crossing time
regardless of the number N of stars in the system. This computation is
questionable in view of the non-linearity of MOND's field equation. A
non-standard approach to the calculation of Tb is developed that can be
extended to MOND whenever discreteness noise generates force fluctuations that
are small compared to the mean-field force. It is shown that this approach
yields standard Newtonian results for systems in which the mean density profile
is either plane-parallel or spherical. In the plane-parallel case we find that
in the deep-MOND regime Tbb scales with N as in the Newtonian case, but is
shorter by the square of the factor by which MOND enhances the gravitational
force over its Newtonian value for the same system. Application of these
results to dwarf galaxies and groups and clusters of galaxies reveals that in
MOND luminosity segregation should be far advanced in groups and clusters of
galaxies, two body relaxation should have substantially modified the density
profiles of galaxy groups, while objects with masses in excess of ~10M_sun
should have spiralled to the centres of dwarf galaxies.(Abridged)


title: Anisotropic convection in rotating proto-neutron stars

abstract:
  We study the conditions for convective instability in rotating, non-magnetic
proto--neutron stars. The criteria that determine stability of nascent neutron
stars are analogous to the Solberg--Hoiland conditions but including the
presence of lepton gradients. Our results show that, for standard angular
velocity profiles, convectively unstable modes with wave-vectors parallel to
the rotation axis are suppressed by a stable angular momentum profile, while
unstable modes with wave-vectors perpendicular to the axis remain unaltered.
Since the wave-vector is perpendicular to the velocity perturbation, the
directional selection of the unstable modes may result in fluid motions along
the direction of the rotation axis. This occurs in rigidly rotating stars as
well as in the inner core of differentially rotating stars. Our results provide
a natural source of asymmetry for proto--neutron stars with the only
requirement that angular velocities be of the order of the convective
characteristic frequency.


title:
Simulation of air shower image in fluorescence light based on energy
  deposits derived from CORSIKA

abstract:
  Spatial distributions of energy deposited by an extensive air shower in the
atmosphere through ionization, as obtained from the CORSIKA simulation program,
are used to find the fluorescence light distribution in the optical image of
the shower. The shower image derived in this way is somewhat smaller than that
obtained from the NKG lateral distribution of particles in the shower. The size
of the image shows a small dependence on the primary particle type.


title:
The growth of supermassive black holes in the centers of galaxies:
  absorption of stars and activity of galactic nuclei

abstract:
  The evolution of a supermassive black hole in the center of galaxy is
considered. We analyze the kinetic equation describing relaxation processes
associated with stellar encounters. The initial distribution function of stars
is assumed to be isothermal, and it changes in accordance with consumption of
stars by the black hole. We calculate the consumption rate and obtain the law
of growth of supermassive black hole, i.e. the dependence of the black hole
mass on time and on the velocity dispersion of stars. The obtained values of
mean black hole mass and mean rate of stars consumption by a black hole are in
reasonable agreement with observational data.


title: On coordinate distances to type Ia supernovae and radio galaxies

abstract:
  The quantum model of the homogeneous and isotropic universe predicts
logarithmic-law dependence of coordinate distance to source on redshift z which
is in good agreement with type Ia supernovae and radio galaxies observations
for the redshift range z = 0.01 - 1.8. A comparison with phenomenological
models with dark energy in the form of cosmological constant and without dark
energy component is made. Fluctuations of the cosmological scale factor about
its average value which can arise in the early universe produce accelerating or
decelerating expansions of space subdomains containing separate sources with
high redshift whereas the universe as a whole expands at a steady rate.


title: ISAAC/VLT observations of a lensed galaxy at z=10.0

abstract:
  We report the first likely spectroscopic confirmation of a z 10.0 galaxy from
our ongoing search for distant galaxies with ISAAC/VLT. Galaxy candidates at z
>~ 7 are selected from ultra-deep JHKs images in the core of gravitational
lensing clusters for which deep optical imaging is also available, including
HST data. The object reported here, found behind Abell 1835, exhibits a faint
emission line detected in the J band, leading to z=10.0 when identified as
Ly-a, in excellent agreement with the photometric redshift determination.
Redshifts z < 7 are very unlikely for various reasons we discuss. The object is
located on the critical lines corresponding to z=9 to 11. The magnification
factor \mu ranges from 25 to 100. For this object we estimate SFR(Ly-a)
(0.8-2.2) Msun/yr and SFR(UV) (47-75) Msun/yr, both uncorrected for lensing.
The steep UV slope indicates a young object with negligible dust extinction.
SED fits with young low-metallicity stellar population models yield (adopting
mu=25) a lensing corrected stellar mass of M*~8.e+6 Msun, and luminosities of
2.e+10 Lsun, corresponding to a dark matter halo of a mass of typically M_tot>~
5.e+8 Msun. In general our observations show that under excellent conditions
and using strong gravitational lensing direct observations of galaxies close to
the ``dark ages'' are feasible with ground-based 8-10m class telescopes.


title: An XMM-Newton study of the RGH 80 galaxy group

abstract:
  We present an X-ray study of the galaxy group RGH 80, observed by XMM-Newton.
The X-ray emission of the gas is detected out to ~ 462h^{-1}_{50} kpc,
corresponding to ~ 0.45 r_{200}. The group is relatively gas rich and luminous
with respect to its temperature of 1.01 +/- 0.01 keV. Using the deprojected
spectral analysis, we find that the temperature peaks at ~ 1.3 keV around
0.11r_{200}, and then decreases inwards to 0.83 keV at the center and outwards
to ~ 70% of the peak value at large radii. Within the central ~ 60 kpc of the
group where the gas cooling time is less than the Hubble time, two-temperature
model with temperatures of 0.82 and 1.51 keV and the Galactic absorption gives
the best fit of the spectra, with ~ 20% volume occupied by the cool component.
We also derive the gas entropy distribution, which is consistent with the
prediction of cooling and/or internal heating models. Furthermore, the
abundances of O, Mg, Si, S, and Fe decrease monotonically with radius. With the
observed abundance ratio pattern, we estimate that ~ 85% or ~ 72% of the iron
mass is contributed by SN Ia, depending on the adopted SN II models.


title:
Density waves in the shearing sheet IV. Interaction with a live dark
  halo

abstract:
  It is shown that if the self-gravitating shearing sheet, a model of a patch
of a galactic disk, is embedded in a live dark halo, this has a strong effect
on the dynamics of density waves in the sheet. I describe how the density waves
and the halo interact via halo particles either on orbits in resonance with the
wave or on non-resonant orbits. Contrary to expectation the presence of the
halo leads to a very considerable enhancement of the amplitudes of the density
waves in the shearing sheet. This effect appears to be the equivalent of the
recently reported enhanced growth of bars in numerically simulated stellar
disks embedded in live dark halos. Finally I discuss the transfer of linear
momentum from a density wave in the sheet to the halo and show that it is
mediated only by halo particles on resonant orbits.


title: An explanation for the unusual IMF in Taurus

abstract:
  In comparison with other well studied star formation regions, Taurus is
unusual in several respects. (i) Its stellar initial mass function (IMF) peaks
at relatively high mass ($\sim 0.8 M_\odot$), but contains very few stars much
more massive than $1 M_\odot$, and is relatively deficient in brown dwarfs.
(ii) It has a higher binary fraction, particularly at large separations. (iii)
Its core mass function is strongly peaked at a few $M_\odot$, and the cores
have extended envelopes and relatively low levels of turbulence.
  We present here the results of an ensemble of hydrodynamic simulations which
suggest that the unusual stellar IMF in Taurus is a direct consequence of the
unusual properties of the cores there. By following the collapse and
fragmentation of cores having properties typical of Taurus, we find that
roughly 50% of the objects formed in a core, predominantly the low-mass ones,
are ejected from the core to form a population of low-mass stars and brown
dwarfs with a flat mass function. The remaining objects form multiple systems
within the core, accreting until their masses approach $1 M_\odot$; this
produces a population of intermediate-mass stars whose mass function peaks at
$\sim 0.8 M_\odot$. Together these two populations reproduce the IMF in Taurus
very well. This demonstrates, for the first time, a direct causal link between
the core mass function and the stellar IMF in a star formation region.


title: WMAP constraints on inflationary models with global defects

abstract:
  We use the cosmic microwave background angular power spectra to place upper
limits on the degree to which global defects may have aided cosmic structure
formation. We explore this under the inflationary paradigm, but with the
addition of textures resulting from the breaking of a global O(4) symmetry
during the early stages of the Universe. As a measure of their contribution, we
use the fraction of the temperature power spectrum that is attributed to the
defects at a multipole of 10. However, we find a parameter degeneracy enabling
a fit to the first-year WMAP data to be made even with a significant defect
fraction. This degeneracy involves the baryon fraction and the Hubble constant,
plus the normalization and tilt of the primordial power spectrum. Hence,
constraints on these cosmological parameters are weakened. Combining the WMAP
data with a constraint on the physical baryon fraction from big bang
nucleosynthesis calculations and high-redshift deuterium abundance, limits the
extent of the degeneracy and gives an upper bound on the defect fraction of
0.13 (95% confidence).


title:
Strong QPOs and High Energy Tail in Simultaneous RXTE/INTEGRAL
  Observations of GRS 1915+105

abstract:
  We present the first results of the timing analysis of our RXTE/INTEGRAL
monitoring campaign on GRS 1915+105. Over the 6 already performed RXTE
observations, we study the presence of Low Frequency QPO (LFQPO), and their
energetic dependences. In a view to understand the QPO phenomenon, we compare
the QPO properties to the spectral behaviour of the source. We propose that
part of the compact jet detected during multi-wavelength observations, could
produce a significant amount of hard X-rays, and hence explain the energy
dependence of the amplitude of the QPOs.


title: The evolution of density perturbations in two quintessence models

abstract:
  In this work we investigate the evolution of matter density perturbations for
two different quintessence models. One of them is based on the Einstein theory
of gravity, while the other is based on the Brans-Dicke scalar tensor theory.
We show that it is possible to constrain the parameter space of the models
using the determinations for the growth rate of perturbations derived from data
of the 2-degree Field Galaxy Redshift Survey.


title: A General Relativistic Magnetohydrodynamics Simulation of Jet Formation

abstract:
  We have performed a fully three-dimensional general relativistic
magnetohydrodynamic (GRMHD) simulation of jet formation from a thin accretion
disk around a Schwarzschild black hole with a free-falling corona. The initial
simulation results show that a bipolar jet (velocity $\sim 0.3c$) is created as
shown by previous two-dimensional axisymmetric simulations with mirror symmetry
at the equator. The 3-D simulation ran over one hundred light-crossing time
units ($\tau_{\rm S} = r_{\rm S}/c$ where $r_{\rm S} \equiv 2GM/c^2$) which is
considerably longer than the previous simulations. We show that the jet is
initially formed as predicted due in part to magnetic pressure from the
twisting the initially uniform magnetic field and from gas pressure associated
with shock formation in the region around $r = 3 r_{\rm S}$. At later times,
the accretion disk becomes thick and the jet fades resulting in a wind that is
ejected from the surface of the thickened (torus-like) disk. It should be noted
that no streaming matter from a donor is included at the outer boundary in the
simulation (an isolated black hole not binary black hole). The wind flows
outwards with a wider angle than the initial jet. The widening of the jet is
consistent with the outward moving torsional Alfv\'{e}n waves (TAWs). This
evolution of disk-jet coupling suggests that the jet fades with a thickened
accretion disk due to the lack of streaming material from an accompanying star.


title:
Oxygen and Magnesium Abundance in the Ultra-Metal-Poor Giants
  CS22949-037 and CS29498-043: Challenges in Models of Atmospheres

abstract:
  We report the results of a non-LTE Fe, O and Mg abundance analysis of the
carbon-nitrogen-rich ultra-metal-poor giants CS29498--043 and CS22949--037. The
abundance of oxygen has been derived from measurements of the oxygen triplet at
7771-5 A in high resolution spectra obtained with KeckI/HIRES and the forbidden
line [OI] 6300 A detected in the TNG/SARG spectra of CS29498-043. Detailed
non-LTE analysis of Fe lines has provided reliable stellar parameters which,
however, do not resolve the oxygen abundance conflict as derived from the OI
7771-5 A triplet and the [OI] 6300 A forbidden lines. We obtained the following
oxygen abundance: for CS22949-037 [O/Fe] =3.13, 1.95; and for CS29498-043;
[O/Fe]=3.02, 2.49, based on the OI 7771-5 A triplet and the [OI] 6300 A
forbidden line, respectively. A similar conflict appears to exist between the
forbidden resonance line MgI 4571 A and several subordinate lines, such as MgI
5172 and 5183 A. Our analysis demonstrates the failure of standard
plane--parallel atmosphere models to describe the physical conditions in the
line-forming regions of these ultra-metal-poor giants.


title:
Tracing Accretion onto Herbig Ae/Be Stars using Near-Infrared
  Spectroscopy

abstract:
  The detection and characterization of accretion processes in the disks
surrounding young stars may be directly relevant to studies of planet
formation. Especially the study of systems with very low accretion rates (<<
10^{-10} M_sun yr^{-1}) is important, since at those rates radial mixing
becomes inefficient and disk material will have to be dissipated into larger
bodies at its present location. In these proceedings, we compare the different
methods of tracing accretion onto Herbig Ae/Be stars and conclude that
high-resolution infrared spectroscopy is currently the only reliable method
that offers the required sensitivity to shed light on this problem.


title: p-mode frequencies in solar-like stars : I. Procyon A

abstract:
  As a part of an on-going program to explore the signature of p-modes in
solar-like stars by means of high-resolution absorption lines pectroscopy, we
have studied four stars (alfaCMi, etaCas A, zetaHer A and betaVir). We present
here new results from two-site observations of Procyon A acquired over twelve
nights in 1999. Oscillation frequencies for l=1 and l=0 (or 2) p-modes are
detected in the power spectra of these Doppler shift measurements. A frequency
analysis points out the dificulties of the classical asymptotic theory in
representing the p-mode spectrum of Procyon A.


title: Missing Lorenz-boosted Circles-in-the-sky

abstract:
  A topologically finite universe, smaller than the observable horizon, will
have circles-in-the-sky: pairs of circles around which the temperature
fluctuations in the cosmic microwave background are correlated. The circles
occur along the intersection of copies of the spherical surface of last
scattering. For any observer moving with respect to the microwave background,
the circles will be deformed into ovals. The ovals will also be displaced
relative to the direction they appear in a comoving frame. The displacement is
the larger of the two effects. In a Lorenz boosted frame, the angular
displacement of a point on the surface of last scattering relative to the
comoving frame is proportional to the velocity. For the Earth's motion, the
effect is on the order of 0.14 degrees at the very worst. If we live in a small
universe and are looking for an identical copy of a spot in the sky, it may be
displaced by as much as 0.14 degrees from where we expect. This can affect all
pattern based searches for the topology of the universe. In particular,
high-resolution searches for circle pairs could be off by this much.


title: The multifrequency monitoring of microquasars. SS433

abstract:
  The principal results of daily observations with the RATAN-600 radio
telescope of X-ray binary with relativistic jets microquasar SS433 in
1986--2003 are presented. We have measured the flux densities at 0.96, 2.3,
3.9, 7.7, 11.2 and 21.7 GHz in different sets, duration from a week to some
months. In general there are 940 observations of SS433 and more than 4500 flux
density measurements in the period. Observations show that radio spectra are
well fitting by a power law. The mean spectral index remained the same,
$-0.60\pm0.14$ during almost 20 years at least, and mean accuracy of the index
determination was better than 0.1 in our multi-frequency observations, i.e. it
was higher than in the intensive two-frequency monitoring of SS433 with the
three-element GBI interferometer. Flux density data and spectra `on-line'
plotting are accessible on the CATS data base site: http://cats.sao.ru/.


title:
Neutrino Processes in Supernovae and Neutrons Stars in Their Infancy and
  Old Age

abstract:
  Neutrino processes in semi-transparent supernova matter, opaque to
semi-transparent protoneutron star matter, and catalyzed neutron stars are
discussed.


title: Identifying young gamma-ray burst fossils

abstract:
  The recent reports of temporal and spectral peculiarities in the early stages
of some afterglows suggest that we may be wrong in postulating a central engine
which becomes dormant after the burst itself. A continually decreasing
postburst relativistic outflow, such as put out by a decaying magnetar, may
continue to be emitted for periods of days or longer, and we argue that it can
be efficiently reprocessed by the ambient soft photon field radiation. Photons
produced either by the postexplosion expansion of the progenitor stellar
envelope or by a binary companion provide ample targets for the relativistic
outflow to interact and produce high energy gamma-rays. The resultant signal
may yield luminosities high enough to be detected with the recently launched
Integral and the Glast experiment now under construction. Its detection will
surely offer important clues for identifying the nature of the progenitor and
possibly constraining whether some route other than single star evolution is
involved in producing a rapidly rotating helium core which in turn, at
collapse, triggers a burst.


title:
The 2dF QSO Redshift Survey - XII. The spectroscopic catalogue and
  luminosity function

abstract:
  We present the final catalogue of the 2dF QSO Redshift Survey (2QZ), based on
Anglo-Australian Telescope 2dF spectroscopic observations of 44576
colour-selected (u b_J r) objects with 18.25<b_J<20.85 selected from APM scans
of UK Schmidt Telescope (UKST) photographic plates. The 2QZ comprises 23338
QSOs, 12292 galactic stars (including 2071 white dwarfs) and 4558 compact
narrow-emission-line galaxies. We obtained a reliable spectroscopic
identification for 86 per cent of objects observed with 2dF. We also report on
the 6dF QSO Redshift Survey (6QZ), based on UKST 6dF observations of 1564
brighter 16<b_J<18.25 sources selected from the same photographic input
catalogue. In total, we identified 322 QSOs spectroscopically in the 6QZ. The
completed 2QZ is, by more than a factor 50, the largest homogeneous QSO
catalogue ever constructed at these faint limits (b_J<20.85) and high QSO
surface densities (35 QSOs deg^-2). As such it represents an important resource
in the study of the Universe at moderate-to-high redshifts. As an example of
the results possible with the 2QZ, we also present our most recent analysis of
the optical QSO luminosity function and its cosmological evolution with
redshift. For a flat, Omega_m=0.3 and Omega_lam=0.7, Universe, we find that a
double power law with luminosity evolution that is exponential in look-back
time, t, of the form L*(z) exp(6.15t), equivalent to an e-folding time of 2Gyr,
provides an acceptable fit to the redshift dependence of the QSO luminosity
function over the range 0.4 < z < 2.1 and M_bJ<-22.5. Evolution described by a
quadratic in redshift is also an acceptable fit, with L*(z)~10^(1.39z-0.29z^2).


title:
The Munich Near--Infrared Cluster Survey (MUNICS) -- VI. The stellar
  masses of K-band selected field galaxies to z ~ 1.2

abstract:
  We present a measurement of the evolution of the stellar mass function in
four redshift bins at 0.4 < z < 1.2 using a sample of more than 5000 K-selected
galaxies drawn from the MUNICS dataset. Our data cover the stellar mass range
10^10 < M/Msun < 10^12. We derive K-band mass-to-light ratios by fitting a grid
of composite stellar population models of varying star formation history, age,
and dust extinction to BVRIJK photometry. We discuss the evolution of the
average mass-to-light ratio as a function of galaxy stellar mass in the K-band
and in the B-band. We compare our stellar mass function at z > 0 to estimates
obtained similarly at z=0. We find that the mass-to-light ratios in the K-band
decline with redshift. This decline is similar for all stellar masses above
$10^10 Msun. Lower mass galaxies have lower mass-to-light ratios at all
redshifts. The stellar mass function evolves significantly to z = 1.2. The
total normalization decreases by a factor of ~2, the characteristic mass (the
knee) shifts towards lower masses and the bright end therefore steepens with
redshift. The amount of number density evolution is a strong function of
stellar mass, with more massive systems showing faster evolution than less
massive systems. We discuss the total stellar mass density of the universe and
compare our results to the values from the literature both at lower and higher
redshift. We find that the stellar mass density at z~1 is roughly 50% of the
local value. Our results imply that the mass assembly of galaxies continues
well after $z \sim 1$. Our data favor a scenario in which the growth of the
most massive galaxies is dominated by accretion and merging rather than star
formation which plays a larger role in the growth of less massive systems.


title:
Discovery of a Dwarf Post-Starburst Galaxy Near a High Column Density
  Ly-alpha Absorber

abstract:
  We report the discovery of a dwarf (M_B = -13.9) post-starburst galaxy
coincident in recession velocity (within uncertainties) with the highest column
density absorber (N_HI = 10^15.85 cm^{-2} at cz = 1586 km/s) in the 3C~273
sightline. This galaxy is by far the closest galaxy to this absorber, projected
just 71 kpc on the sky from the sightline. The mean properties of the stellar
populations in this galaxy are consistent with a massive starburst ~3.5 Gyrs
ago, whose attendant supernovae, we argue, could have driven sufficient gas
from this galaxy to explain the nearby absorber. Beyond the proximity on the
sky and in recession velocity, the further evidence in favor of this conclusion
includes both a match in the metallicities of absorber and galaxy, and the fact
that the absorber has an overabundance of Si/C, suggesting recent type II
supernova enrichment. Thus, this galaxy and its ejecta are the expected
intermediate stage in the fading dwarf evolutionary sequence envisioned by
Babul & Rees to explain the abundance of faint blue galaxies at intermediate
redshifts.


title:
Exploring the mirror matter interpretation of the DAMA experiment: Has
  the dark matter problem been solved?

abstract:
  The self consistency between the impressive DAMA annual modulation signal and
the differential energy spectrum is an important test for dark matter
candidates.Mirror matter-type dark matter passes this test while other dark
matter candidates, including standard (spin-independent) WIMPs and
mini-electric charged particle dark matter, do not do so well.We argue that the
unique properties of mirror matter-type dark matter seem to be just those
required to fully explain the data, suggesting that the dark matter problem has
finally been solved.


title: Introducing Enzo, an AMR Cosmology Application

abstract:
  In this paper we introduce Enzo, a 3D MPI-parallel Eulerian block-structured
adaptive mesh refinement cosmology code. Enzo is designed to simulate
cosmological structure formation, but can also be used to simulate a wide range
of astrophysical situations. Enzo solves dark matter N-body dynamics using the
particle-mesh technique. The Poisson equation is solved using a combination of
fast fourier transform (on a periodic root grid) and multigrid techniques (on
non-periodic subgrids). Euler's equations of hydrodynamics are solved using a
modified version of the piecewise parabolic method. Several additional physics
packages are implemented in the code, including several varieties of radiative
cooling, a metagalactic ultraviolet background, and prescriptions for star
formation and feedback. We also show results illustrating properties of the
adaptive mesh portion of the code. Enzo is publicly available and can be
downloaded at http://cosmos.ucsd.edu/enzo/ .


title:
Nonlinear electrodynamics and the gravitational redshift of highly
  magnetised neutron stars

abstract:
  The idea that the nonlinear electromagnetic interaction, i. e., light
propagation in vacuum, can be geometrized was developed by Novello et al.
(2000) and Novello & Salim (2001). Since then a number of physical consequences
for the dynamics of a variety of systems have been explored. In a recent paper
Mosquera Cuesta & Salim (2003) presented the first astrophysical study where
such nonlinear electrodynamics (NLEDs) effects were accounted for in the case
of a highly magnetized neutron star or pulsar. In that paper the NLEDs was
invoked {\it a l\`a} Euler-Heisenberg, which is an infinite series expansion of
which only the first term was used for the analisys. The immediate consequence
of that study was an overall modification of the space-time geometry around the
pulsar, which is ``perceived'', in principle, only by light propagating out of
the star. This translates into an significant change in the surface redshift,
as inferred from absorption (emission) lines observed from a super magnetized
pulsar. The result proves to be even more dramatic for the so-called magnetars,
pulsars endowed with magnetic ($B$) fields higher then the Schafroth quantum
electrodynamics critical $B$-field. Here we demonstrate that the same effect
still appears if one calls for the NLEDs in the form of the one rigorously
derived by Born & Infeld (1934) based on the special relativistic limit for the
velocity of approaching of an elementary particle to a pointlike electron [From
the mathematical point of view, the Born & Infeld (1934) NLEDs is described by
an exact Lagrangean, whose dynamics has been successfully studied in a wide set
of physical systems.].


title:
Conservation of both current and helicity in a quadrupolar model for
  solar flares

abstract:
  A model for a solar flare, involving magnetic reconnection transferring flux
and current between current-carrying magnetic loops connecting two pairs of
footpoints, is generalized to include conservation of magnetic helicity during
reconnection, as well as conservation of current at all four footpoints. For a
set of force-free loops, with the $i$th loop having flux $F_i$ and current
$I_i$, the self and mutual helicities are proportional to the self and mutual
inductances with the constant of proportionality determined by
$\alpha_i=F_i/\mu_0I_i$. In a constant-$\alpha$ model, the change in magnetic
energy is proportional to the change in helicity, and conservation of helicity
implies conservation of magnetic energy, so that a flare cannot occur. In a
quadrupolar model, with $\alpha_1>\alpha_2$ initially, $\alpha_1$ increases and
$\alpha_2$ decreases when flux and current are transferred from loops~1 and~2
to loops~3 and~4. A model that conserves both current and helicity is
constructed; it depends on the initial $\alpha$s, and otherwise is somewhat
simpler than when helicity is neglected.


title: Multiverse cosmological models

abstract:
  Recent advances in string theory and inflationary cosmology have led to a
surge of interest in the possible existence of an ensemble of cosmic regions,
or universes, among the members of which key physical parameters, such as the
masses of elementary particles and the coupling constants, might assume
different values. The observed values in our cosmic region are then attributed
to an observer selection effect (the so-called anthropic principle). The
assemblage of universes has been dubbed the multiverse. In this paper I review
the multiverse concept and the criticisms that have been advanced against it on
both scientific and philosophical grounds.


title: Tachyonic dark matter

abstract:
  Recent attempts to explain the dark matter and energy content of the universe
have involved some radical extensions of standard physics, including
quintessence, phantom energy, additional space dimensions and variations in the
speed of light. In this paper I consider the possibility that some dark matter
might be in the form of tachyons. I show that, subject to some reasonable
assumptions, a tachyonic cosmological fluid would produce distinctive effects,
such as a surge in quantum vacuum energy and particle creation, and a change in
the conventional temperature-time relation for the normal cosmological
material. Possible observational consequences are discussed.