title: The Morphological decomposition of Abell A868

abstract:
  We report on the morphological luminosity functions (LFs) and radial profiles
derived for the galaxy population within the rich cluster Abell 868 (z=0.153)
based purely on Hubble Space Telescope Imaging in F606W. We recover Schechter
functions for early(E/S0)-, mid(Sabc)- and late(Sd/Irr)- type galaxies. The
early-, mid- and late- types are all consistent with the recent field
morphological LFs based on recent analysis of the Sloan Digital Sky Survey --
Early Data Release (SDSS-EDR; Nakamura et al 2003). From a detailed error
analysis, including clustering of the background population, we note that
improved statistics can only come from combining data from many clusters. We
also examine the luminosity-density and number-density profiles as a function
of morphology and draw the following conclusions: (1) The galaxies responsible
for the steep faint-end slope are predominantly of late-type morphology, (2)
The cluster core is dominated by elliptical galaxies, (3) The core is devoid of
late-types systems, (4) The luminosity-density as a function of morphological
type is skewed towards early-types when compared to the field, (5) Up to half
of the elliptical galaxies may have formed from the spiral population through
core disk-destruction process(es). We believe the most plausible explanation is
the conventional one that late-types are destroyed during transit through the
cluster core and that mid-types are converted into early-types through a
similar process, which destroys the outer disk and results in a more tightly
bound population of core ellipticals.[Abridged].


title: Large scale properties in turbulent spherically symmetric accretion

abstract:
  The role of turbulence in a spherically symmetric accreting system has been
studied on very large spatial scales of the system. This is also a highly
subsonic flow region and here the accreting fluid has been treated as nearly
incompressible. It has been shown here that the coupling of the mean flow and
the turbulent fluctuations, gives rise to a scaling relation for an effective
"turbulent viscosity". This in turn leads to a dynamic scaling for sound
propagation in the accretion process. As a consequence of this scaling, the
sonic horizon of the transonic inflow solution is shifted inwards, in
comparison with the inviscid flow.


title: Photometric structure of polar-ring galaxies

abstract:
  The results of B, V, R surface photometry of three polar-ring galaxies (PRGs)
-- A0017+2212, UGC1198, UGC4385 -- are presented. The data were acquired at the
6-m telescope of the Special Astrophysical Observatory of the Russian Academy
of Sciences. It was shown that all three galaxies are peculiar late-type
spirals in the state of ongoing interaction or merging. We discuss available
photometric properties of the PRGs with spiral hosts and consider the
Tully-Fisher relation for different types of PRGs. In agreement with Iodice et
al. (2003), we have shown that true PRGs demonstrate ~1/3 larger maximum
rotation velocities than spiral galaxies of the same luminosity. Peculiar
objects with forming polar structures satisfy, on average, the Tully-Fisher
relation for disk galaxies but with large scatter.


title:
Atmospheres and Spectra of Strongly Magnetized Neutron Stars -- III.
  Partially Ionized Hydrogen Models

abstract:
  We construct partially ionized hydrogen atmosphere models for magnetized
neutron stars in radiative equilibrium with surface fields B=10^12-5 \times
10^14 G and effective temperatures T_eff \sim a few \times 10^5-10^6 K. These
models are based on the latest equation of state and opacity results for
magnetized, partially ionized hydrogen plasmas that take into account various
magnetic and dense medium effects. The atmospheres directly determine the
characteristics of thermal emission from isolated neutron stars. For the models
with B=10^12-10^13 G, the spectral features due to neutral atoms lie at extreme
UV and very soft X-ray energy bands and therefore are difficult to observe.
However, the continuum flux is also different from the fully ionized case,
especially at lower energies. For the superstrong field models (B\ga 10^14 G),
we show that the vacuum polarization effect not only suppresses the proton
cyclotron line as shown previously, but also suppresses spectral features due
to bound species; therefore spectral lines or features in thermal radiation are
more difficult to observe when the neutron star magnetic field is \ga 10^14 G.


title: Modeling The Nucleosynthesis Of Massive Stars

abstract:
  This overview discusses issues relevant to modeling nucleosynthesis in type
II supernovae and implications of detailed studies of the ejecta. After a brief
presentation of the most common approaches to stellar evolution and
parameterized explosions, the relevance of a number of nuclei to obtain
information on the evolution and explosion mechanisms is discussed. The paper
is concluded by an outlook on multi-dimensional simulations.


title: The Tully-Fisher relation at intermediate redshift

abstract:
  Using the Very Large Telescope in Multi Object Spectroscopy mode, we have
observed a sample of 113 field spiral galaxies in the FORS Deep Field (FDF)
with redshifts in the range 0.1<z<1.0. The galaxies were selected upon apparent
brightness (R<23) and encompass all late spectrophotometric types from Sa to
Sdm/Im. Spatially resolved rotation curves have been extracted for 77 galaxies
and fitted with synthetic velocity fields taking into account all observational
effects from inclination and slit misalignment to seeing and slit width. We
also compared different shapes for the intrinsic rotation curve. To gain robust
values of V_max, our analysis is focussed on galaxies with rotation curves
which extend well into the region of constant rotation velocity at large radii.
If the slope of the local Tully-Fisher relation (TFR) is held fixed, we find
evidence for a mass-dependent luminosity evolution which is as large as up to 2
mag for the lowest-mass galaxies, but is small or even negligible for the
highest-mass systems in our sample. In effect, the TFR slope is shallower at
z~0.5 in comparison to the local sample. We argue for a mass-dependent
evolution of the mass-to-light ratio. An additional population of blue,
low-mass spirals does not seem a very appealing explanation. The flatter tilt
we find for the distant TFR is in contradiction to the predictions of recent
semi-analytic simulations.


title:
Low Luminosity Type II Supernovae: Spectroscopic and Photometric
  Evolution

abstract:
  In this paper we present spectroscopic and photometric observations for four
core collapse supernovae (SNe), namely SNe 1994N, 1999br, 1999eu and 2001dc.
Together with SN 1997D, we show that they form a group of exceptionally
low-luminosity events. These SNe have narrow spectral lines (indicating low
expansion velocities) and low luminosities at every phase (significantly lower
than those of typical core-collapse supernovae). The very low luminosity during
the ^{56}Co radioactive decay tail indicates that the mass of ^{56}Ni ejected
during the explosion is much smaller (M(Ni) ~ 2-8 x 10^{-3} Mo) than the
average (M(Ni) ~ 6-10 x 10^{-2} Mo). Two supernovae of this group (SN 1999br
and SN 2001dc) were discovered very close to the explosion epoch, allowing us
to determine the lengths of their plateaux (~ 100 days) as well as
establishiing the explosion epochs of the other, less-completely observed SNe.
It is likely that this group of SNe represent the extreme low-luminosity tail
of a single continuous distribution of SN II-P events. Their kinetic energy is
also exceptionally low. Although an origin from low mass progenitors has also
been proposed for low-luminosity core-collapse SNe, recent work provides
evidence in favour of the high mass progenitor scenario. The incidence of these
low--luminosity SNe could be as high as 4-5$ $ of all type II SNe.


title:
The Star Formation History of NGC 1705: a Post-Starburst Galaxy on the
  Verge of Activity

abstract:
  We infer the star formation history in different regions of the blue compact
dwarf NGC 1705 by comparing synthetic color-magnitude diagrams with HST optical
and near-infrared photometry. We find that NGC 1705 is not a young galaxy
because its star formation commenced at least 5 Gyr ago. On the other hand, we
confirm the existence of a recent burst of star formation between 15 and 10 Myr
ago. We also find evidence for new strong activity, which started 3 Myr ago and
is still continuing. The old population is spread across the entire galaxy,
while the young and intermediate stars are more concentrated in the central
regions. We derive an almost continuous star formation with variable rate, and
exclude the presence of long quiescent phases between the episodes during the
last ~1 Gyr. The central regions experienced an episode of star formation of
\~0.07 Msun/yr (for a Salpeter initial mass function [IMF]) 15 to 10 Myr ago.
This coincides with the strong activity in the central super star cluster. We
find a rate of ~0.3 Msun/yr for the youngest ongoing burst which started ~3 Myr
ago. This is higher than in other dwarfs and comparable to the rate of NGC
1569. The star formation rate of earlier episodes is not especially high and
falls in the range 10^{-3}-10^{-1} Msun/yr. The IMF is close to the Salpeter
value or slightly steeper.


title: Dynamics of Ferromagnetic Walls: Gravitational Properties

abstract:
  We discuss a new mechanism which allows domain walls produced during the
primordial electroweak phase transition. We show that the effective surface
tension of these domain walls can be made vanishingly small due to a peculiar
magnetic condensation induced by fermion zero modes localized on the wall. We
find that in the perfect gas approximation the domain wall network behaves like
a radiation gas. We consider the recent high-red shift supernova data and we
find that the corresponding Hubble diagram is compatible with the presence in
the Universe of a ideal gas of ferromagnetic domain walls. We show that our
domain wall gas induces a completely negligible contribution to the large-scale
anisotropy of the microwave background radiation.


title: Internal kinematics of spiral galaxies in distant clusters Part I

abstract:
  We introduce our project on galaxy evolution in the environment of rich
clusters aiming at disentangling the importance of specific interaction and
galaxy transformation processes from the hierarchical evolution of galaxies in
the field. Emphasis is laid on the examination of the internal kinematics of
disk galaxies through spatially resolved MOS spectroscopy with FORS at the VLT.
First results are presented for the clusters MS1008.1-1224 (z=0.30),
Cl0303+1706 (z=0.42), and Cl0413-6559 (F1557.19TC) (z=0.51). Out of 30 cluster
members with emission-lines, 13 galaxies exhibit a rotation curve of the
universal form rising in the inner region and passing over into a flat part.
The other members have either intrinsically peculiar kinematics (4), or too
strong geometric distortions (9) or too low S/N (4 galaxies) for a reliable
classification of their velocity profiles. The 13 cluster galaxies for which a
maximum rotation velocity could be derived are distributed in the Tully--Fisher
diagram very similar to field galaxies from the FORS Deep Field that have
corresponding redshifts and do not show any significant luminosity evolution
with respect to local samples. The same is true for seven galaxies observed in
the cluster fields that turned out not to be members. The mass-to-light ratios
of the 13 TF cluster spirals cover the same range as the distant field
population indicating that their stellar populations were not dramatically
changed by possible clusterspecific interaction phenomena. The cluster members
with distorted kinematics may be subject to interaction processes but it is
impossible to determine whether these processes also lead to changes in the
overall luminosity of their stellar populations.


title: Star-forming galaxies in the 2dFGRS

abstract:
  We examine the environment of star-forming galaxies selected in the 2dFGRS.
We find that bright star-forming galaxies display a significant deficit of
faint neighbours relative to passive galaxies. If a deficit in fainter
companions implies a smaller mass halo, data support a scenario predicting
star-formation to be suppressed in all systems more massive than 10^{13}
M_sun,rather than in clusters only.


title: Concluding Remarks

abstract:
  The mood at this conference is summarized in David Hughes' comment, ``this
decade will be amazing.'' We've just had a pretty good ten years of advances in
cosmology and extragalactic astronomy; why should we expect a repeat, another
decade of comparable or even greater progress? The obvious answer is that there
still are many more questions than answers in cosmology, and a considerable
number of the questions will be addressed by research programs planned and in
progress: we certainly are going to learn new things. But beyond that is the
fact that there is no practical limit to the hierarchy of interesting topics to
explore in this subject. I organize my comments on the state of research, and
the prospects for substantial new developments in the coming decade of
multi-wavelength cosmology, around the concept of social constructions.


title: Universal spectral shape of AGN with high accretion rate

abstract:
  The spectra of radio quiet and NLS1 galaxies show suprising similarity in
their shape. They seem to scale only with the accretion rate but not with
central black hole mass. We consider two mechanisms modifying the disk
spectrum. First, the outer parts of the disk are irradiated by the flux
emerging from the inner parts. This is due to the scattering of the flux by the
extended hot medium (warm absorber). Second process is connected with the
development of the disk warm Comptonizing skin above the disk and/or coronae.
Our scenario applies only to object with relatively high luminosity to the
Eddington luminosity ratio for which disk evaporation is inefficient.


title:
0103-72.6: A New Oxygen-Rich Supernova Remnant in the Small Magellanic
  Cloud

abstract:
  0103$-$72.6, the second brightest X-ray supernova remnant (SNR) in the Small
Magellanic Cloud (SMC), has been observed with the {\it Chandra X-Ray
Observatory}. Our {\it Chandra} observation unambiguously resolves the X-ray
emission into a nearly complete, remarkably circular shell surrounding bright
clumpy emission in the center of the remnant. The observed X-ray spectrum for
the central region is evidently dominated by emission from reverse shock-heated
metal-rich ejecta. Elemental abundances in this ejecta material are
particularly enhanced in oxygen and neon, while less prominent in the heavier
elements Si, S, and Fe. We thus propose that 0103$-$72.6 is a new
``oxygen-rich'' SNR, making it only the second member of the class in the SMC.
The outer shell is the limb-brightened, soft X-ray emission from the swept-up
SMC interstellar medium. The presence of O-rich ejecta and the SNR's location
within an H{\small II} region attest to a massive star core-collapse origin for
0103$-$72.6. The elemental abundance ratios derived from the ejecta suggest an
$\sim$18 M$_{\odot}$ progenitor star.


title:
The Evolution of Massive Stars. I. Red Supergiants in the Magellanic
  Clouds

abstract:
  We investigate the red supergiant (RSG) content of the SMC and LMC using
multi-object spectroscopy on a sample of red stars previously identified by
{\it BVR} CCD photometry. We obtained high accuracy ($<1$ km s$^{-1}$) radial
velocities for 118 red stars seen towards the SMC and 167 red stars seen
towards the LMC, confirming most of these (89% and 95%, respectively) as red
supergiants (RSGs). Spectral types were also determined for most of these RSGs.
We find that the distribution of spectral types is skewed towards earlier type
at lower metallicities: the average (median) spectral type is K5-7 I in the
SMC, M1 I in the LMC, and M2 I in the Milky Way. We argue that RSGs in the
Magellanic Clouds are 100deg (LMC) and 300deg (SMC) cooler than Galactic RSGs
of the same spectral type. We compare the distribution of RSGs in the H-R
diagram to that of various stellar evolutionary models; we find that none of
the models produce RSGs as cool and luminous as what is actually observed. In
all of our H-R diagrams, however, there is an elegant sequence of decreasing
effective temperatures with increasing luminosities; explaining this will be an
important test of future stellar evolutionary models.


title: Local and Global Variations of The Fine Structure Constant

abstract:
  Using the BSBM varying-alpha theory, with dark matter dominated by magnetic
energy, and the spherical collapse model for cosmological structure formation,
we have studied the effects of the dark-energy equation of state and the
coupling of alpha to the matter fields on the space and time evolution of
alpha. We have compared its evolution inside virialised overdensities with that
in the cosmological background, using the standard ($% \Lambda =0$) $CDM$ model
of structure formation and the dark-energy modification, $wCDM$. We find that,
independently of the model of structure formation one considers, there is
always a difference between the value of alpha in an overdensity and in the
background. In a $SCDM$ model, this difference is the same, independent of the
virialisation redshift of the overdense region. In the case of a $wCDM$ model,
especially at low redshifts, the difference depends on the time when
virialisation occurs and the equation of state of the dark energy. At high
redshifts, when the $wCDM$ model becomes asymptotically equivalent to the
$SCDM$ one, the difference is constant. At low redshifts, when dark energy
starts to dominate the cosmological expansion, the difference between alpha in
a cluster and in the background grows. The inclusion of the effects of
inhomogeneity leads naturally to no observable local time variations of alpha
on Earth and in our Galaxy even though time variations can be significant on
quasar scales. The inclusion of the effects of inhomogeneous cosmological
evolution are necessary if terrestrial and solar-system bounds on the time
variation of the fine structure 'constant' are to be correctly compared with
extragalactic data.


title:
A Snapshot Survey for Gravitational Lenses Among z>=4.0 Quasars: I. The
  z>5.7 Sample

abstract:
  Over the last few years, the Sloan Digital Sky Survey (SDSS) has discovered
several hundred quasars with redshift between 4.0 and 6.4. Including the
effects of magnification bias, one expects a priori that an appreciable
fraction of these objects are gravitationally lensed. We have used the Advanced
Camera for Surveys on the Hubble Space Telescope to carry out a snapshot
imaging survey of high-redshift SDSS quasars to search for gravitationally
split lenses. This paper, the first in a series reporting the results of the
survey, describes snapshot observations of four quasars at z = 5.74, 5.82, 5.99
and 6.30, respectively. We find that none of these objects has a lensed
companion within 5 magnitudes with a separation larger than 0.3 arcseconds;
within 2.5 magnitudes, we can rule out companions within 0.1 arcseconds. Based
on the non-detection of strong lensing in these four systems, we constrain the
z~6 luminosity function to a slope of beta>-4.63 (3 sigma), assuming a break in
the quasar luminosity function at M_{1450}^*=-24.0. We discuss the implications
of this constraint on the ionizing background due to quasars in the early
universe. Given that these quasars are not highly magnified, estimates of the
masses of their central engines by the Eddington argument must be taken
seriously, possibly challenging models of black hole formation.


title: Morphology and kinematics of Lynds 1642

abstract:
  The high latitude translucent molecular cloud L1642 has been mapped in the
J=1-0 and J=2-1 transitions of 12CO, 13CO and C18O using the SEST radio
telescope. We have analysed the morphology and velocity structure of the cloud
using the Positive Matrix Factorization (PMF) method. The results show that
L1642 is composed of a main structure at radial velocity 0.2 km/s while the
higher velocity components at ~0.5 and 1.0 km/s form an incomplete ring around
it, suggesting an expanding shell structure. Fainter emission extends to the
north with a still higher velocity of up to 1.6 km/s. Such a velocity structure
suggests an elongated morphology in the line of sight direction. The physical
properties of the cloud have been investigated assuming LTE conditions, but
non-LTE radiative transfer models are also constructed for the 13CO
observations. We confirm that L1642 follows an r^-1 density distribution in its
outer parts while the distribution is considerably flatter in the core. The
cloud is close to virial equilibrium. In an Appendix the PMF results are
compared with the view obtained through the analysis of channel maps and by the
use of Principal Component Analysis (PCA). Both PMF and PCA present the
observations as a linear combination of basic spectral shapes that are
extracted from the data. Comparison of the methods shows that the PMF method in
particular is able to produce a presentation of the complex velocity that is
both compact and easily interpreted.


title:
Evolutionary and pulsational properties of low-mass white dwarf stars
  with oxygen cores resulting from close binary evolution

abstract:
  The present work is designed to explore the evolutionary and pulsational
properties of low-mass white dwarfs with carbon/oxygen cores. In particular, we
follow the evolution of a 0.33 Msun white dwarf remnant in a self-consistent
way with the predictions of nuclear burning, element diffusion and the history
of the white dwarf progenitor. Attention is focused on the occurrence of
hydrogen shell flashes induced by diffusion processes during cooling phases.
The evolutionary stages prior to the white dwarf formation are also fully
accounted for by computing the conservative binary evolution of an initially
2.5-Msun Pop. I star with a 1.25 Msun companion, and period P_i= 3 days.
Evolution is followed down to the domain of the ZZ Ceti stars on the white
dwarf cooling branch. We find that chemical diffusion induces the occurrence of
an additional hydrogen thermonuclear flash which leads to stellar models with
thin hydrogen envelopes. As a result, a fast cooling is encountered at advanced
stages of evolution. In addition, we explore the adiabatic pulsational
properties of the resulting white dwarf models. As compared with their
helium-core counterparts, low-mass oxygen-core white dwarfs are characterized
by a pulsational spectrum much more featured, an aspect which could eventually
be used for distinguishing both types of stars if low-mass white dwarfs were in
fact found to pulsate as ZZ Ceti-type variables. Finally, we perform a
non-adiabatic pulsational analysis on the resulting carbon/oxygen low-mass
white dwarf models.


title: Cluster Masses Accounting for Structure along the Line of Sight

abstract:
  Weak gravitational lensing of background galaxies by foreground clusters
offers an excellent opportunity to measure cluster masses directly without
using gas as a probe. One source of noise which seems difficult to avoid is
large scale structure along the line of sight. Here I show that, by using
standard map-making techniques, one can minimize the deleterious effects of
this noise. The resulting uncertainties on cluster masses are significantly
smaller than when large scale structure is not properly accounted for, although
still larger than if it was absent altogether.


title: Nucleosynthesis in Outflows from the Inner Regions of Collapsars

abstract:
  We consider nucleosynthesis in outflows originating from the inner regions of
viscous accretion disks formed after the collapse of a rotating massive star.
We show that wind-like outflows driven by viscous and neutrino heating can
efficiently synthesize Fe-group elements moving at near-relativistic
velocities. The mass of 56Ni synthesized and the asymptotic velocities attained
in our calculations are in accord with those inferred from observations of
SN1998bw and SN2003dh. These steady wind-like outflows are generally proton
rich, characterized by only modest entropies, and consequently synthesize
essentially nothing heavier than the Fe-group elements. We also discuss
bubble-like outflows resulting from rapid energy deposition in localized
regions near or in the accretion disk. These intermittent ejecta emerge with
low electron fraction and are a promising site for the synthesis of the A=130
r-process peak elements.


title:
Detectability of Weakly Interacting Massive Particles in the Sagittarius
  Dwarf Tidal Stream

abstract:
  Tidal streams of the Sagittarius dwarf spheroidal galaxy (Sgr) may be
showering dark matter onto the solar system and contributing approx (0.3--23)%
of the local density of our Galactic Halo. If the Sagittarius galaxy contains
WIMP dark matter, the extra contribution from the stream gives rise to a
step-like feature in the energy recoil spectrum in direct dark matter
detection. For our best estimate of stream velocity (300 km/sec) and direction
(the plane containing the Sgr dwarf and its debris), the count rate is maximum
on June 28 and minimum on December 27 (for most recoil energies), and the
location of the step oscillates yearly with a phase opposite to that of the
count rate. In the CDMS experiment, for 60 GeV WIMPs, the location of the step
oscillates between 35 and 42 keV, and for the most favorable stream density,
the stream should be detectable at the 11 sigma level in four years of data
with 10 keV energy bins. Planned large detectors like XENON, CryoArray and the
directional detector DRIFT may also be able to identify the Sgr stream.


title: Galaxy Evolution from the DEEP2 Galaxy Redshift Survey

abstract:
  The DEEP2 Galaxy Redshift Survey is now well underway, having already
measured the redshifts to ~5600 galaxies in its first season of observations.
Here I briefly review the survey itself, before discussing in more detail some
of the initial science results to have recently appeared in the literature. In
particular, the potential of the survey to characterize galaxy evolution is
discussed, with special emphasis on the role of spectral classification. Some
of the applications of this classification, namely to the quantification of
galaxy clustering and the measurement of galaxy environments are also discussed
here.


title: The CMB Quadrupole in a Polarized Light

abstract:
  The low quadrupole of the cosmic microwave background (CMB), measured by COBE
and confirmed by WMAP, has generated much discussion recently. We point out
that the well-known correlation between temperature and polarization
anisotropies of the CMB further constrains the low multipole anisotropy data.
This correlation originates from the fact that the low-multipole polarization
signal is sourced by the CMB quadrupole as seen by free electrons during the
relatively recent cosmic history. Consequently, the large-angle temperature
anisotropy data make restrictive predictions for the large-angle polarization
anisotropy, which depend primarily on the optical depth for electron scattering
after cosmological recombination, tau. We show that if current cosmological
models for the generation of large angle anisotropy are correct and the
COBE/WMAP data are not significantly contaminated by non-CMB signals, then the
observed C_te amplitude on the largest scales is discrepant at the 99.8% level
with the observed C_tt for the concordance LCDM model with tau=0.10. Using
tau=0.17, the preferred WMAP model-independent value, the discrepancy is at the
level of 98.5%.


title: Optical Spectroscopy of IRAS 02091+6333

abstract:
  We present a detailed spectroscopic investigation, spanning four winters, of
the asymptotic giant branch (AGB) star IRAS 02091+6333. Zijlstra & Weinberger
(2002) found a giant wall of dust around this star and modelled this unique
phenomenon. However their work suffered from the quality of the optical
investigations of the central object. Our spectroscopic investigation allowed
us to define the spectral type and the interstellar foreground extinction more
precisely. Accurate multi band photometry was carried out. This provides us
with the possibility to derive the physical parameters of the system. The
measurements presented here suggest a weak irregular photometric variability of
the target, while there is no evidence of a spectroscopic variability over the
last four years.


title: Does GRS 1915+105 exhibit "canonical" black-hole states?

abstract:
  We have analysed RXTE data of the superluminal source GRS 1915+105 in order
to investigate if, despite its extreme variability, it also exhibits the
canonical source states that characterise other black-hole candidates. The
phenomenology of GRS 1915+105 has been described in terms of three states
(named A, B and C) based on their hardness ratios and position in the
colour-colour diagram. We have investigated the connection between these states
and the canonical behaviour and found that the shape of the power spectral
continuum and the values of the best-fit model parameters to the noise
components in all three states indicate that the source shows properties
similar to the canonical very high state.


title:
An empirical criterion to classify T Tauri stars and substellar analogs
  using low-resolution optical spectroscopy

abstract:
  We have compiled and studied photometric and spectroscopic data published in
the literature of several star forming regions and young open clusters (Orion,
Taurus, IC348, Sco-Cen Complex, Chamaeleon I, TW Hya association, sigma Orionis
cluster, IC2391, alpha Per cluster and the Pleiades). Our goal was to seek the
definition of a simple empirical criterion to classify stars or brown dwarfs
which are accreting matter from a disk on the sole basis of low-resolution
optical spectroscopic data. We show that using Halpha equivalent widths and
spectral types we can statistically classify very young stars and brown dwarfs
as classical T Tauri stars and substellar analogs. As a boundary between
accreting and non accreting objects, we use the saturation limit of
chromospheric activity at Log L(Halpha)/L(bol)=-3.3 (determined in the open
clusters). We discuss the uncertainties in the classification scheme due to the
occurrence of flares. We have used this spectroscopic empirical criterion to
classify objects found in the literature, and we compute the fraction of
accreting objects in several star forming regions. The fraction of accreting
objects appears to decrease from about 50% to about 5% from 1 Myr to 10 Myr for
both stars and brown dwarfs.


title: Parsec Scale Properties of Markarian 501

abstract:
  We present the results of a high angular resolution study of the BL Lac
object Markarian 501 in the radio band. We consider data taken at 14 different
epochs, ranging between 1.6 GHz and 22 GHz in frequency, and including new
Space VLBI observations obtained on 2001 March 5 and 6 at 1.6 and 5 GHz. We
study the kinematics of the parsec-scale jet and estimate its bulk velocity and
orientation with respect to the line of sight. Limb brightened structure in the
jet is clearly visible in our data and we discuss its possible origin in terms
of velocity gradients in the jet. Quasi-simultaneous multi-wavelength
observations allow us to map the spectral index distribution and to compare it
to the jet morphology. Finally, we estimate the physical parameters of the
parsec-scale jet.


title:
^{56}Ni mass in type IIP SNe: Light curves and H-alpha luminosities
  diagnostics

abstract:
  We analyse late-time observations, available photometry and spectra, of a
sample of type II plateau supernovae (SNe IIP). The possibility of using
H$\alpha$ luminosity at the nebular epoch as a tracer of $^{56}$Ni mass in this
class of objects is investigated, yielding a consistency with the
photometry-based estimates within 20%. Interesting correlations are found and
their impacts on our present understanding of the physics of core collapse SNe
are discussed.


title: JEM-X background models

abstract:
  Background and determination of its components for the JEM-X X-ray telescope
on INTEGRAL are discussed. A part of the first background observations by JEM-X
are analysed and results are compared to predictions. The observations are
based on extensive imaging of background near the Crab Nebula on revolution 41
of INTEGRAL. Total observing time used for the analysis was 216502 s, with the
average of 25 cps of background for each of the two JEM-X telescopes. JEM-X1
showed slightly higher average background intensity than JEM-X2. The detectors
were stable during the long exposures, and weak orbital phase dependence in the
background outside radiation belts was observed. The analysis yielded an
average of 5 cps for the diffuse background, and 20 cps for the instrument
background. The instrument background was found highly dependent on position,
both for spectral shape and intensity. Diffuse background was enhanced in the
central area of a detector, and it decreased radially towards the edge, with a
clear vignetting effect for both JEM-X units. The instrument background was
weakest in the central area of a detector and showed a steep increase at the
very edges of both JEM-X detectors, with significant difference in spatial
signatures between JEM-X units. According to our modelling, instrument
background dominates over diffuse background in all positions and for all
energies of JEM-X.


title:
Evidence of a decrease of kHz QPO peak separation towards low
  frequencies in 4U 1728-34 (GX 354-0)

abstract:
  We have produced the colour-colour diagram of all the observations of 4U
1728-34 available in the Rossi X-ray Timing Explorer public archive (from 1996
to 2002) and found observations filling in a previously reported 'gap' between
the island and the banana X-ray states. We have made timing analysis of these
gap observations and found, in one observation, two simultaneous kHz
quasi-periodic oscillations (QPOs). The timing parameters of these kHz QPOs fit
in the overall trend of the source. The 'lower' kHz QPO has a centroid
frequency of ~308 Hz. This is the lowest 'lower' kHz QPO frequency ever
observed in 4U 1728-34. The peak frequency separation between the 'upper' and
the 'lower' kHz QPO is 274+/-11 Hz, significantly smaller than the constant
value of ~350 Hz found when the 'lower' kHz QPO frequency is between ~500 and
800 Hz. This is the first indication in this source for a significant decrease
of kHz QPO peak separation towards low frequencies. We briefly compare the
result to theoretical models for kHz QPO production.


title: The TNG EROs Spectroscopic Identification Survey (TESIS)

abstract:
  We are carrying on a near-IR very low resolution spectroscopic follow-up in
parallel with XMM-Newton observations of a complete sample of ~30 bright
(K'<18.5) Extremely Red Objects (EROs) selected over an area of 360 arcmin^2 of
the MUNICS survey. We here present the preliminary results of the spectroscopic
and X-ray data analysis.


title:
In-Situ Particle Acceleration in Extragalactic Radio Hot Spots:
  Observations Meet Expectations

abstract:
  We discuss, in terms of particle acceleration, the results from optical VLT
observations of hot spots associated with radio galaxies. On the basis of
observational and theoretical grounds, it is shown that:
  1. relatively low radio-radio power hot spots are the optimum candidates for
being detected at optical waves. This is supported by an unprecedented optical
detection rate of 70% out of a sample of low radio power hot spots.
  2. the shape of the synchrotron spectrum of hot spots is mainly determined by
the strength of the magnetic field in the region. In particular, the break
frequency, related to the age of the oldest electrons in the hot spots, is
found to increase with decreasing synchrotron power and magnetic field
strength.
  Both observational results are in agreement with an in-situ particle
acceleration scenario.


title:
Constraints on AGN accretion disc viscosity derived from continuum
  variability

abstract:
  We estimate a value of the viscosity parameter in AGN accretion discs for the
PG quasar sample. We assume that optical variability on time-scales of months
to years is caused by local instabilities in the inner accretion disc.
Comparing the observed variability time-scales to the thermal time-scales of
alpha-disc models we obtain constraints on the viscosity parameter for the
sample. We find that, at a given L/L_Edd, the entire sample is consistent with
a single value of the viscosity parameter, alpha. We obtain constraints of 0.01
< alpha < 0.03 for 0.01 < L/L_Edd < 1.0. This narrow range suggests that these
AGN are all seen in a single state, with a correspondingly narrow spread of
black hole masses or accretion rates. The value of alpha we derive is
consistent with predictions by current simulation s in which MHD turbulence is
the primary viscosity mechanism.


title:
Ideal MHD solution to the $\sigma$ problem in Crab-like pulsar winds and
  general asymptotic analysis of magnetized outflows

abstract:
  Using relativistic, steady, axisymmetric, ideal magnetohydrodynamics (MHD) we
analyze the super-Alfvenic regime of a pulsar wind by means of solving the
momentum equation along the flow as well as in the transfield direction.
Employing a self-similar model, we demonstrate that ideal MHD can account for
the full acceleration from high (>>1) to low (<<1) values of $\sigma$, the
Poynting-to-matter energy flux ratio. The solutions also show a transition from
a current-carrying to a return-current regime, partly satisfying the
current-closure condition. We discuss the kind of the boundary conditions near
the base of the ideal MHD regime that are necessary in order to have the
required transition from high to low $\sigma$ in realistic distances, and argue
that this is a likely case for an equatorial wind. Examining the MHD
asymptotics in general, we extend the analysis of Heyvaerts & Norman and
Chiueh, Li, & Begelman by including two new elements: classes of quasi-conical
and parabolic field line shapes that do not preclude an efficient and much
faster than logarithmic acceleration, and the transition $\sigma=\sigma_c$
after which the centrifugal forces (poloidal and azimuthal) are the dominant
terms in the transfield force-balance equation.


title: High Resolution Chandra Spectroscopy of Gamma Cassiopeia (B0.5IVe)

abstract:
  gamma Cas has long been famous for its unique hard X-ray characteristics. We
report herein on a 53 ks Chandra HETGS observation of this target. An
inspection of our spectrum shows that it is quite atypical for a massive star,
with abnormally weak Fe XXV, XXVI lines, Ly-alpha lines of H-like species from
Fe XVII, XXIII, XXIV, S XVI, Si XIV, Mg XII, Ne X, O VII, VIII, and N VII.
Also, line ratios of the rif-triplet of for a few He-like ions XVII are
consistent with the dominance of collisional atomic processes. Yet, the
presence of Fe and Si fluorescence K features indicates that photoionization
also occurs in nearby cold gas. The line profiles indicate a mean velocity at
rest and a broadening of 500 km/s. A global fitting analysis of the line and
continuum spectrum finds that there are 3-4 plasma emission components. The
dominant hot (12 keV) component and has a Fe abundance of 0.22 solar. Some
fraction of this component (10-30%) is heavily absorbed. The other 2-3
components, with temperatures 0.1, 0.4, 3 keV, are "warm," have a nearly solar
composition, a lower column absorption, and are responsible for most other
emission lines. The strength of the fluorescence features and the dual-column
absorption model for the hot plasma component suggest the presence near the hot
sites of a cold gas structure with a column density of 10^23 cm^-2. Since this
value is consistent with theoretical estimates of the vertical disk column of
this star, these attributes suggest that the X-rays originate near the star or
disk. It is possible that the Fe anomaly in the hot component is related to the
First Ionization Potential effect found in coronal structures around active
cool stars. This would be yet another indication that the X-rays -rays are
produced in the immediate vicinity of the Be star.


title: On the origin of X-ray Flashes

abstract:
  We use the cannonball (CB) model of gamma ray bursts (GRBs) and their
afterglows (AGs) to analyze the observational data on X-ray flashes (XRFs) and
their AGs. We show that the observations support the CB-model interpretation
that XRFs, like GRBs, are produced by the explosions of core-collapse
supernovae (SNe) akin to SN1998bw, by jets of highly-relativistic CBs. The XRFs
and GRBs are intrinsically identical objects, but the XRFs are viewed from
angles (relative to the jet direction) which are typically a few times larger
than the typical viewing angles of ``classical'', long-duration GRBs. There
should be XRFs, not observed so far, with durations similar to those of short
GRBs.


title:
Keck Spectroscopy of Red Giant Stars in the Vicinity of M31's Massive
  Globular Cluster G1

abstract:
  We present results from a Keck spectroscopic survey of red giants in a field
near M31's major axis, ~34kpc in projection from the nucleus, near the globular
cluster G1. We use multislit LRIS spectroscopy to measure the CaII triplet in
41 stars with apparent mags 20<I<22. Of these, 23 stars are found to have
radial velocities v<-200km/s indicating they are giants in M31; the rest are
probably foreground Galactic stars. About 2/3 of the M31 members concentrate at
v=-451km/s, with a velocity spread of sigma=27km/s, which suggests that they
belong to the outer disk or perhaps a cold debris trail in the halo. The
group's mean velocity is consistent with that of nearby HI gas and models of
M31's disk velocity field but not with G1 or M31's systemic velocity. We use
V,I photometry to estimate a mean metallicity of <[Fe/H]>=-0.8 for these
potential M31 outer disk stars. Six of the 23 M31 members v and [Fe/H] values
consistent with those of G1 (after accounting forits intrinsic spread in both):
one of these stars lies within G1's projected tidal radius and is a likely
member; the remaining 5 stars are not physically close to G1 but may represent
its tidal debris. More data are needed to confirm the nature of these 5 stars
as it is likely that they represent M31's smooth halo population. We might have
expected to detect tidal debris if G1 were the remnant core of a dwarf galaxy
being accreted by M31; instead, the majority of M31 giants in this field are
metal-rich and belong to what is evidently the outer disk of M31, and only a
small fraction (<~20%) could possibly have originated in G1.


title: Deep Photometry in a Remote M31 Major Axis Field Near G1

abstract:
  We present photometry from Hubble Space Telescope (HST)/Wide Field Planetary
Camera 2 parallel imagery of a remote M31 field at a projected distance of
about 34 kpc from the nucleus near the SW major axis. This field is near the
globular cluster G1, and near one of the candidate tidal plumes identified by
Ferguson et al. (2002). The F606W (V) and F814W (I) images were obtained in
parallel with Space Telescope Imaging Spectrograph spectroscopy of G1 (GO-9099)
and total 7.11 hours of integration time -- the deepest HST field in the outer
disk of M31 to date, reaching to V ~ 28. The color-magnitude diagram of the
field shows a clearly-defined red clump at V = 25.25 and a red giant branch
consistent with [Fe/H] ~ -0.7. The lack of a blue horizontal branch contrasts
with other M31 halo fields, the Andromeda dwarf spheroidals, and with the
nearby globular cluster G1. Comparing the observed luminosity function to the
Padova models, we find that at least some of the stellar population must be
younger than 6 - 8 Gyr. The outermost detected neutral hydrogen gas disk of M31
lies only 2 kpc in projection from our field. The finding that some giants in
the field have radial velocities close to that of the neutral hydrogen gas
(Reitzel, Guhathakurta, & Rich 2003) leads us to conclude that our field
samples the old, low-surface-brightness disk rather than the true Population II
spheroid.


title: Erupting Dwarf Novae in the Large Magellanic Cloud

abstract:
  We report the first likely detections of erupting Dwarf Novae (DN) in an
external galaxy: the Large Magellanic Cloud. Six candidates were isolated from
approximately a million stars observed every second night over 11 nights with
the CTIO 8K x 8K Mosaic2 CCD imager. Artificial dwarf nova and completeness
tests suggest that we are seeing only the brightest of the LMC DN, probably SS
Cygni-like CVs, but possibly SU UMa-type cataclysmics undergoing
superoutbursts. We derive crude but useful limits on the LMC DN surface
density, and on the number of DN in the LMC. Many thousands of cataclysmic
variables in the Magellanic Clouds can be discovered and characterized with 8
meter class telescopes.


title:
The AGN Content of Ultraluminous IR Galaxies: High Resolution VLA
  Imaging of the IRAS 1Jy ULIRG Sample

abstract:
  This paper presents the results of a high resolution radio imaging survey of
83 of the 118 ultraluminous infrared galaxies (ULIRGs) in the IRAS 1 Jy ULIRG
sample. We have observed these ULIRGs at 15GHz with the Very Large Array (VLA).
We find that ~75% of Seyferts (both type 1 and 2) and LINERs have radio nuclei
which are compact at our 150mas resolution. The detection rate of HII nuclei is
significantly lower (32%); the detections among these are preferentially HII +
LINER/Seyfert composite nuclei. Among ULIRGs with multiple optical or near-IR
nuclei our observations detected only one (or no) nucleus; in these the radio
detection is typically towards the brightest near-IR nucleus. The compactness
of the radio sources, the higher detection rates in AGN-type nuclei than HII
nuclei, the preferential detection of nuclei with unresolved point sources in
the near-IR, the low soft X-ray to nuclear radio luminosity ratio (arguing
against thermal emission powering the radio nuclei), and the lack of
correlation between radio power and Halpha luminosity, all support an origin of
the detected radio nuclei in AGN related activity. This result is especially
interesting for LINER ULIRGs for which signatures of AGNs have often been
ambiguous in other wavebands. Such a high incidence of AGN would provide, for
the first time, a large sample in which to study the interplay between AGN,
starbursts, and galaxy mergers.


title: Restless Quasar Activity: From BeppoSAX to Chandra and XMM-Newton

abstract:
  We briefly review some of the progress made in the last decade in the study
of the X-ray properties of the quasar population from the luminous, local
objects observed by BeppoSAX to the large, rapidly increasing population of z>4
quasars detected by Chandra and XMM-Newton in recent years.


title: Chameleon Fields: Awaiting Surprises for Tests of Gravity in Space

abstract:
  We present a novel scenario where a scalar field acquires a mass which
depends on the local matter density: the field is massive on Earth, where the
density is high, but is essentially free in the solar system, where the density
is low. All existing tests of gravity are satisfied. We predict that
near-future satellite experiments could measure an effective Newton's constant
in space different than that on Earth, as well as violations of the equivalence
principle stronger than currently allowed by laboratory experiments.


title: Lensing Studies with Diffuse Backgrounds

abstract:
  The current weak lensing measurements of the large scale structure are mostly
related to statistical study of background galaxy ellipticities. We consider a
possibility to extend lensing studies with intrinsically unresolved sources and
suggest that spatial fluctuations in the integrated diffuse emission from these
sources can be used for a lensing reconstruction. Examples of upcoming
possibilities include the diffuse background generated by dusty starburst
galaxies at far-infrared wavelengths, first stars and galaxies in near-infrared
wavelengths, and the background related to 21 cm emission by neutral gas in the
general intergalactic medium prior to reionization. While methods developed to
extract lensing information from cosmic microwave background (CMB) temperature
and polarization data can be easily modified to study lensing properties using
diffuse backgrounds at other wavelengths, we suggest that the lensing
extraction from these backgrounds using higher order non-Gaussian clustering
information alone may not be the best approach. In contrast to CMB
anisotropies, reasons for this include the lack of features in the clustering
power spectrum such that the resulting lensing modification to the angular
power spectrum of low-redshift diffuse backgrounds, at arcminute angular
scales, is insignificant. While the use of low redshift backgrounds for lensing
studies will be challenging, due to confusing foregrounds among other reasons,
the use of suggested backgrounds will extend the reconstruction of the
integrated matter power spectrum out to redshifts of 15 to 30, and will bridge
the gap between current and upcoming galaxy lensing studies out to, at most, a
redshift of a few and planned weak lensing studies with CMB out to the last
scattering surface at a redshift of 1100.


title: OGLE-2003-BLG-262: Finite-Source Effects from a Point-Mass Lens

abstract:
  We analyze OGLE-2003-BLG-262, a relatively short, t_E=12.5+-0.1day,
microlensing event generated by a point-mass lens transiting the face of a K
giant source in the Galactic bulge. We use the resulting finite-source effects
to measure the angular Einstein radius, theta_E=195+-17muas, and so constrain
the lens mass to the full-width half-maximum interval 0.08 < M/M_sun < 0.54.
The lens-source relative proper motion is mu_rel = 27+-2 km/s/kpc. Both values
are typical of what is expected for lenses detected toward the bulge. Despite
the short duration of the event, we detect marginal evidence for a "parallax
asymmetry", but argue that this is more likely to be induced by acceleration of
the source, a binary lens, or possibly by statistical fluctuations. Although
OGLE-2003-BLG-262 is only the second published event to date in which the lens
transits the source, such events will become more common with the new OGLE-III
survey in place. We therefore give a detailed account of the analysis of this
event to facilitate the study of future events of this type.


title:
Direct constraints on the dark matter self-interaction cross-section
  from the merging galaxy cluster 1E0657-56

abstract:
  We compare new maps of the hot gas, dark matter, and galaxies for 1E0657-56,
a cluster with a rare, high-velocity merger occurring nearly in the plane of
the sky. The X-ray observations reveal a bullet-like gas subcluster just
exiting the collision site. A prominent bow shock gives an estimate of the
subcluster velocity, 4500 km/s, which lies mostly in the plane of the sky. The
optical image shows that the gas lags behind the subcluster galaxies. The
weak-lensing mass map reveals a dark matter clump lying ahead of the
collisional gas bullet, but coincident with the effectively collisionless
galaxies. From these observations, one can directly estimate the cross-section
of the dark matter self-interaction. That the dark matter is not fluid-like is
seen directly in the X-ray -- lensing mass overlay; more quantitative limits
can be derived from three simple independent arguments. The most sensitive
constraint, sigma/m<1 cm^2/g, comes from the consistency of the subcluster
mass-to-light ratio with the main cluster (and universal) value, which rules
out a significant mass loss due to dark matter particle collisions. This limit
excludes most of the 0.5-5 cm^2/g interval proposed to explain the flat mass
profiles in galaxies. Our result is only an order-of-magnitude estimate which
involves a number of simplifying, but always conservative, assumptions;
stronger constraints may be derived using hydrodynamic simulations of this
cluster.


title: Cold molecular gas in cooling flow clusters of galaxies

abstract:
  The results of a CO line survey in central cluster galaxies with cooling
flows are presented. Cold molecular gas is detected with the IRAM 30m
telescope, through CO(1-0) and CO(2-1) emission lines in 6-10 among 32
galaxies. The corresponding gas masses are between 3.10^8 and 4.10^10 Msol.
These results are in agreement with recent CO detections by Edge (2001). A
strong correlation between the CO emission and the Halpha luminosity is also
confirmed. Cold gas exists in the center of cooling flow clusters and these
detections may be interpreted as an evidence of the long searched very cold
residual of the hot cooling gas.


title: MoMaF : The Mock Map Facility

abstract:
  We present the Mock Map Facility, a powerful tool to generate mock catalogues
or images from semi-analytically post-processed snapshots of cosmological
N-body simulations. The paper describes in detail an efficient technique to
create such mocks from the GALICS semi-analytic model, providing the reader
with an accurate quantification of the artifacts it introduces at every step.
We show that replication effects introduce a negative bias on the clustering
signal -- typically peaking at less than 10 percent around the correlation
length. We also thoroughly discuss how the clustering signal is affected by
finite volume effects, and show that it vanishes at scales larger than about a
tenth of the simulation box size. For the purpose of analysing our method, we
show that number counts and redshift distributions obtained with GALICS and
MOMAF compare well to K-band observations and to the 2dFGRS. Given finite
volume effects, we also show that the model can reproduce the APM angular
correlation function. The MOMAF results discussed here are made publicly
available to the astronomical community through a public database. Moreover, a
user-friendly Web interface (http://galics.iap.fr) allows any user to recover
her/his own favourite galaxy samples through simple SQL queries. The
flexibility of this tool should permit a variety of uses ranging from extensive
comparisons between real observations and those predicted by hierarchical
models of galaxy formation, to the preparation of observing strategies for deep
surveys and tests of data processing pipelines.


title: Turbulent Ambipolar Diffusion: Numerical Studies in 2D

abstract:
  Under ideal MHD conditions the magnetic field strength should be correlated
with density in the interstellar medium (ISM). However, observations indicate
that this correlation is weak. Ambipolar diffusion can decrease the
flux-to-mass ratio in weakly ionized media; however, it is generally thought to
be too slow to play a significant role in the ISM except in the densest
molecular clouds. Turbulence is often invoked in astrophysical problems to
increase transport rates above the (very slow) laminar values predicted by
kinetic theory. We describe a series of numerical experiments addressing the
problem of turbulent transport of magnetic fields in weakly ionized gases. We
show, subject to various geometrical and physical restrictions, that turbulence
in a weakly ionized medium rapidly diffuses the magnetic flux to mass ratio
through the buildup of appreciable ion-neutral drifts on small scales. These
results are applicable to the fieldstrength - density correlation in the ISM,
as well as the merging of flux systems such as protostar and accretion disk
fields or protostellar jets with ambient matter, and the vertical transport of
galactic magnetic fields.


title: An Unsplit, Cell-Centered Godunov Method for Ideal MHD

abstract:
  We present a second-order Godunov algorithm for multidimensional, ideal MHD.
Our algorithm is based on the unsplit formulation of Colella (J. Comput. Phys.
vol. 87, 1990), with all of the primary dependent variables centered at the
same location. To properly represent the divergence-free condition of the
magnetic fields, we apply a discrete projection to the intermediate values of
the field at cell faces, and apply a filter to the primary dependent variables
at the end of each time step. We test the method against a suite of linear and
nonlinear tests to ascertain accuracy and stability of the scheme under a
variety of conditions. The test suite includes rotated planar linear waves, MHD
shock tube problems, low-beta flux tubes, and a magnetized rotor problem. For
all of these cases, we observe that the algorithm is second-order accurate for
smooth solutions, converges to the correct weak solution for problems involving
shocks, and exhibits no evidence of instability or loss of accuracy due to the
possible presence of non-solenoidal fields.


title: The Structure of High Redshift Galactic Halos

abstract:
  Observations of multiple or lensed QSOs at high redshift can be used to probe
transverse structure in intervening absorption systems. Here we present results
obtained from STIS spectroscopy of the unique triply imaged QSO APM08279+5255
at z = 3.9 and study the coherence scales of intervening low and high
ionization absorbers.


title: Spectropolarimetry and Modeling of the Eclipsing T Tauri Star KH 15D

abstract:
  KH 15D is a strongly variable T Tauri star in the young star cluster NGC 2264
that shows a decrease in flux of 3.5 magnitudes lasting for 18 days and
repeating every 48 days. The eclipsing material is likely due to orbiting dust
or rocky bodies in a partial ring or warped disk that periodically occults the
star. We measured the polarized spectrum in and out of eclipse at the Keck and
Palomar observatories. Outside of the eclipse, the star exhibited low
polarization consistent with zero. During eclipse, the polarization increased
dramatically to ~2% across the optical spectrum, while the spectrum had the
same continuum shape as outside of eclipse and exhibited emission lines of much
larger equivalent width, as previously seen. From the data, we conclude that
(a) the scattering region is uneclipsed; (b) the scattering is nearly
achromatic; (c) the star is likely completely eclipsed so that the flux during
eclipse is entirely due to scattered light, a conclusion also argued for by the
shape of the ingress and egress. We argue that the scattering is not due to
electrons, but may be due to large dust grains of size ~10 micron, similar to
the interplanetary grains which scatter the zodiacal light. We construct a
warped-disk model with an extended dusty atmosphere which reproduces the main
features of the lightcurve, namely (a) a gradual decrease before ingress due to
extinction in the atmosphere (similar for egress); (b) a sharper decrease
within ingress due to the optically-thick base of the atmosphere; (c) a
polarized flux during eclipse which is 0.1% of the total flux outside of
eclipse, which requires no fine-tuning of the model. (abridged)


title: Equation of state and opacities for hydrogen atmospheres of magnetars

abstract:
  The equation of state and radiative opacities of partially ionized, strongly
magnetized hydrogen plasmas, presented in a previous paper [ApJ 585, 955
(2003), astro-ph/0212062] for the magnetic field strengths 8.e11 G < B < 3.e13
G, are extended to the field strengths 3.e13 G < B < 1.e15 G, relevant for
magnetars. The first- and second-order thermodynamic functions and radiative
opacities are calculated and tabulated for 5.e5 < T < 4.e7 K in a wide range of
densities. We show that bound-free transitions give an important contribution
to the opacities in the considered range of B in the outer neutron-star
atmosphere layers. Unlike the case of weaker fields, bound-bound transitions
are unimportant.


title:
The puzzlingly large Ca II triplet absorption in dwarf elliptical
  galaxies

abstract:
  We present central CaT, PaT, and CaT* indices for a sample of fifteen dwarf
elliptical galaxies (dEs). Twelve of these have CaT* ~ 7 A and extend the
negative correlation between the CaT* index and central velocity dispersion
sigma, which was derived for bright ellipticals (Es), down to 20 < sigma < 55
km/s. For five dEs we have independent age and metallicity estimates. Four of
these have CaT* ~ 7 A, much higher than expected from their low metallicities
(-1.5 < [Z/H] < -0.5). The observed anti-correlation of CaT* as a function of
sigma or Z is in flagrant disagreement with theory. We discuss some of the
amendments that have been proposed to bring the theoretical predictions into
agreement with the observed CaT*-values of bright Es and how they can be
extended to incorporate also the observed CaT*-values of dEs. Moreover, 3 dEs
in our sample have CaT* ~ 5 A, as would be expected for metal-poor stellar
systems. Any theory for dE evolution will have to be able to explain the
co-existence of low-CaT* and high-CaT* dEs at a given mean metallicity. This
could be the first direct evidence that the dE population is not homogeneous,
and that different evolutionary paths led to morphologically and kinematically
similar but chemically distinct objects.


title: Tidal radii of globular clusters and the mass of the Milky Way

abstract:
  Tidal radii of remote globular clusters (R_{GC}>= 35 kpc) are used to provide
constraints of the mass profile of the Milky Way galaxy that are independent of
kinematic data. The available data are consistent with the profile of an
isothermal sphere with circular velocity V_c = 220 +/- 40 km/s in the radial
range 35 kpc < R_{GC} < 100 kpc, in good agreement with all recent estimates.
The more robust constraint at large distances from the galactic center is
provided by NGC 2419, yelding an enclosed mass of ~ 1.3 (+2.9/-1.0) * 10**12
M_{sun} at R_{GC}= 90 kpc.


title: Evolution of galaxies in clusters: semi-analytic models and observations

abstract:
  We present two different projects. The first one is related to the
development of a semi-analytic model to follow the formation, the evolution and
chemical enrichment of cluster galaxies in a hierarchical dark matter model.
The second project concerns the comparison between high resolution N-body
simulations of clusters of galaxies with the EDisCS observational dataset.


title:
The weak-line T Tauri star V410Tau I. A multi-wavelength study of
  variability

abstract:
  We present the results of an intensive coordinated monitoring campaign in the
optical and X-ray wavelength ranges of the low-mass, pre-main sequence star
V410Tau carried out with the aim to study the relation between various
indicators for magnetic activity that probe emission from different atmospheric
layers: optical photometric star spot (rotation) cycle, chromospheric Halpha
emission, and coronal X-rays. Two X-ray pointings were carried out with the
Chandra satellite simultaneously with the optical observations, and centered
near the maximum and minimum levels of the optical lightcurve. A relation of
their different count levels to the rotation period of the dominating spot is
not confirmed by a third Chandra observation carried out some months later,
during another minimum of the 1.87d cycle. Similarly we find no indications for
a correlation of the Halpha emission with the spots' rotational phase. The
extraordinary stability of the largest spot is confirmed by long-term
photometric and radial velocity measurements. Joining our optical photometry
with previous data we provide a new estimate for the dominant periodicity of
V410Tau. This updated value removes systematic offsets of the time of minimum
observed in data taken over the last decade. Furthermore, the combination of
the new data with published measurements taken during the last decade allows us
to examine long-term changes in the mean light level of the photometry of
V410Tau. A variation on the timescale of 5.4yr is suggested. Assuming that this
behavior is truely cyclic V410Tau is the first pre-main sequence star on which
an activity cycle is detected.


title: AD Leonis: Flares observed by XMM-Newton and Chandra

abstract:
  The M-dwarf AD Leonis has been observed with the Reflection Grating
Spectrometers and the European Photon Imaging Camera aboard XMM-Newton and also
with the Low Energy Transmission Grating Spectrometer aboard the Chandra X-ray
Observatory. In the observation taken with XMM-Newton five large flares
produced by AD Leo were identified and only one in the observation taken with
Chandra. A quiescent level to the lightcurves is difficult to define, since
several smaller flares mutually overlap each other. However, we defined a
quasi-steady state outside of obvious flares or flare decays. The spectra from
the flare state and the quasi-steady state are analysed separately. From these
spectra the temperature structure was derived with a multi-temperature model
and with a differential emission measure model. The multi-temperature model was
also used to determine the relative abundances of C, N, O, Ne, Mg, Si, S, and
Fe. He-like ions, such as O VII and Ne IX, produce line triplets which are used
to determine or constrain the electron temperature and electron density of the
corresponding ion. During the flare state a higher emission measure at the
hottest temperature is found for both XMM-Newton and Chandra observations. The
derived abundances suggest the presence of an inverse First Ionization
Potential effect in the corona of AD Leo.


title:
Bound on the time variation of the fine structure constant driven by
  quintessence

abstract:
  The bound on the time variation of the fine structure constant ($\alpha$)
driven by the dynamics of quintessence scalar field which is coupled to
electromagnetism is discussed using phenomenological quintessential models
constrained by SNIa and CMB observations. We find that those models allowing
early quintessence give the largest variation $\Delta\alpha$ at the decoupling
epoch. Furthermore, the fifth force experiments imply that
$\Delta\alpha/\alpha$ is less than about 0.1%.


title: Optimized in-flight absolute calibration for extended CMB surveys

abstract:
  Accurate measurements of the Cosmic Microwave Background (CMB) anisotropy
call for high precision and reliability of the in-flight calibration. For
extended surveys the CMB dipole provides an excellent calibration source at
frequencies lower than 200 GHz; however poorly known foreground emissions, such
as diffuse galactic components, complicate the signal and introduce a
systematic error in the calibration. We show that introducing a weight function
that takes into account the uncertainty in the a priori knowledge of the sky,
allows us to substantially improve the calibration accuracy with respect to
methods involving galactic latitude cuts. This new method is tested for
Planck-LFI radiometers at 30 and 100 GHz. On short time scales (less than 1
day) the absolute calibration of each channel can be recovered with an overall
1-2% accuracy. We also consider the effect of CMB anisotropy itself on the
calibration, and find that knowledge of the CMB pattern on large scales is
needed to keep the short-time scale calibration accuracy within 1%


title:
Extended X-ray emission in the high redshift quasar GB 1508+5714 at
  z=4.3

abstract:
  We report the discovery of extended X-ray emission around the powerful
high-redshift quasar GB 1508+5714 at z=4.3, revealed in a long Chandra ACIS
observation. The emission feature is 3-4 arcsec away from the quasar core,
which corresponds to a projected distance of about 25 kpc. The X-ray spectrum
is best fitted with a power law of photon index 1.92+-0.35 (90 per cent c.l.).
The X-ray flux and luminosity reach 9.2x10^-15 ergs (0.5-8 keV) and 1.6x10^45
erg s^-1 (2.7-42.4 keV rest frame, Omega_Lambda=0.73, Omega_m=0.27, H_0=71 km
s^-1 Mpc^-1), which is about 2 percent of the total X-ray emission of the
quasar. We interpret the X-ray emission as inverse Compton scattering of Cosmic
Microwave Background photons. The scattering relativistic electron population
could either be a quasi-static diffuse cloud fed by the jet, or an outer
extension of the jet with a high bulk Lorentz factor. We argue that the lack of
an obvious detection of radio emission from the extended component could be a
consequence of Compton losses on the electron population, or of a low magnetic
field. Extended X-ray emission produced by inverse Compton scattering may be
common around high redshift radio galaxies and quasars, demonstrating that
significant power is injected into their surrounding by powerful jets.


title: On application of multi-colour photometry of $\delta$ Scuti stars

abstract:
  In $\delta$ Scuti star models, the photometric amplitudes and phases exhibit
a strong dependence on convection, which enters through the complex parameter,
$f$, which describes the bolometric flux variation. We present a new method of
extracting simultaneously $\ell$ and $f$ from multi-colour data and apply it to
several $\delta$ Scuti stars. The inferred values of $f$ are sufficiently
accurate to yield an useful constraint on models of stellar convection.
  In addition, if the identified mode is radial, the multi-passband data may be
used to refine global stellar parameters. Finally, the usage of radial velocity
measurements to our method improves significantly determination of $\ell$ and
$f$.


title: Scale of Homogeneity of the Universe from WMAP

abstract:
  We review the physics of the Grishchuck-Zel'dovich effect which describes the
impact of large amplitude, super-horizon gravitational field fluctuations on
the Cosmic Microwave Background anisotropy power spectrum. Using the latest
determination of the spectrum by WMAP, we infer a lower limit on the present
length-scale of such fluctuations of 3927 times the cosmological particle
horizon (at the 95% confidence level).


title: A Fallback Disk Model for Ultraluminous X-ray Sources

abstract:
  Current stellar evolution models predict that during the core collapse of
massive stars, a considerable amount of the stellar material will fall back
onto the compact, collapsed remnants (neutron stars or black holes), usually in
the form of an accretion disk. This triggers rapid mass accretion onto, e.g.,
the black hole, and produces energetic explosions known as Gamma-ray bursts.
However it is very difficult to prove the existence of an accretion disk around
newborn black holes observationally. Here we demonstrate that some of the
ultraluminous X-ray sources in nearby galaxies, which are associated with
supernova remnants, may be black holes accreting from their fallback disks,
i.e., they have evolved from collapsars. Since it is almost certain that there
is an accretion disk around these black holes, this would for the first time
lend the observational support to the collapsar model.


title: Magnitude systems in old star catalogues

abstract:
  The current system of stellar magnitudes first introduced by Hipparchus was
strictly defined by Norman Robert Pogson in 1856. He based his system on
Ptolemy's star catalogue `Almagest', recorded in about 137 A.D., and defined
the magnitude-intensity relationship on a logarithmic scale.
  Stellar magnitudes observed with the naked eye recorded in seven old star
catalogues were analyzed in order to examine the visual magnitude systems.
Despite that psychophysists have proposed that human's sensitivities are on a
power-law scale, it is shown that the degree of agreement is far better for a
logarithmic magnitude than a power-law magnitude. It is also found that light
ratios in each star catalogue nearly equal to 2.512, excluding the brightest
(1st) and the dimmest (6th and dimmer) stars being unsuitable for the
examination. It means that the visual magnitudes in old star catalogues fully
agree with Pogson's logarithmic scale.


title:
Spawning and merging of Fourier modes and phase coupling in cosmological
  density bispectrum

abstract:
  In the standard picture of cosmological structure formation, initially
random-phase fluctuations are amplified by non-linear gravitational instability
to produce a final distribution of mass which is highly non-Gaussian and has
highly-coupled Fourier phases. We use the Zel'dovich approximation in one
dimension to elucidate the onset of non-linearity including mode spawning,
merging and coupling. We show that as gravitational clustering proceeds,
Fourier modes are spawned from parent ones, with their phases following a
harmonic relationship with the wavenumbers. Spawned modes could also merge
leading to modulation of the amplitudes and phases which consequently breaks
such harmonic relation. We also use simple toy models to demonstrate that
bispectrum, Fourier transform of connected three-point correlation functions,
measures phase coupling at most at the second-order only when the special
wavenumber-phase harmonic relation holds. Phase information is therefore partly
registered in bispectrum and it takes a complete hierarchy of polyspectra to
fully characterize gravitational non-linearity.


title: Pulsar Astrometry with the VLBA

abstract:
  Many features of the Very Long Baseline Array (VLBA) contrive to make it the
best telescope for pulsar astrometry. The measured proper motions and
parallaxes allow distances and transverse velocities to be determined. These in
turn provide clues to questions spanning nuclear astrophysics on scales of
10^-23 m to the distribution of gas in the Galaxy on scales of 10^20 m. Three
pulsars are discussed in this paper. Among pulsars, B0950+08 has the most
accurate VLBI-determined parallax. B1133+16 has a very high transverse
velocity; its radial velocity is discussed. B0656+14 is a thermally detected
neutron star. Determination of its distance has allowed its radius to be
measured and its association with the Monogem ring supernova remnant (SNR) to
be established, allowing a long-standing question in cosmic ray astrophysics to
be addressed.


title:
Project of a superfluid He3 detector for direct detection of
  non-baryonic dark matter : MACHe3

abstract:
  MACHe3 (MAtrix of Cells of superfluid Helium 3) is a project of non-baryonic
Dark Matter search using superfluid He3 as sensitive medium. Simulations on a
high granularity matrix show very good rejection against background events.
First results on a prototype cell are very encouraging. Neutron detection has
been highlighted as well as cosmic muon detection. A phenomenological study has
been done with the DarkSUSY code to investigate complementarity of MACHe3 with
existing Dark Matter detectors.


title: Development of the Universe and New Cosmology

abstract:
  Cosmology is undergoing an explosive period of activity, fueled both by new,
accurate astrophysical data and by innovative theoretical developments.
Cosmological parameters such as the total density of the Universe and the rate
of cosmological expansion are being precisely measured for the first time, and
a consistent standard picture of the Universe is beginning to emerge. Recent
developments in cosmology give rise the intriguing possibility that all
structures in the Universe, from superclusters to planets, had a
quantum-mechanical origin in its earliest moments. Furthermore, these ideas are
not idle theorizing, but predictive, and subject to meaningful experimental
test. We review the concordance model of the development of the Universe, as
well as evidence for the observational revolution that this field is going
through. This already provides us with important information on particle
physics, which is inaccessible to accelerators.


title: New analysis in the field of open cluster Collinder 223

abstract:
  The present study of the open cluster Collinder 223 (Cr 223) has been mainly
depended on the photoelectric data of Claria & Lapasset (1991; hereafter CL91).
This data of CL91 has been used with the cluster's image of AAO-DSS in order to
re-investigate and improve the main parameters of Cr 223. Stellar count has
been achieved to determine the stellar density, the cluster's center and the
cluster's diameter. In addition, the luminosity function, mass function, and
the total mass of the cluster have been estimated.


title: Clues to the origin of metals in the Ly-alpha forest

abstract:
  We analyze the z=2 Ly-alpha and CIV forest along two adjacent lines-of-sight
at high S/N and spectral resolution to assess the question of the origin of
metals in the intergalactic medium. We find that the gas containing detectable
amounts of metals (as seen in absorption by CIV) is less quiescent on scales of
a few kpc than the gas without metals. Although it is difficult to discriminate
unequivocally between possible sources of enrichment and the extent to which
each contributes to line-of-sight differences, those suggest that the
metal-enriched systems are bound to galaxies (i.e., they do not arise in the
IGM nor in galactic winds).


title:
Inhomogenous Primordial Baryon Distributions on Sub-Galactic Scales:
  High-z Galaxy Formation with WDM

abstract:
  For the Warm Dark Matter (WDM) cosmological model the implications of
strongly inhomogenous, primordial baryon distribution on sub-galactic scales
for Big Bang Nucleosynthesis, Cosmic Microwave Background anisotropies and
Galaxy Formation (including fully non-linear evolution to z=0) are discussed,
and the inflationary theory leading to such distributions is briefly reviewed.
It is found that Big Bang Nucleosynthesis is essentially unaffected relative to
SBBN and that the change in recombination history at z~1500-700 relative to
``standard'' theory leads to differences in the anisotropy and polarization
power spectra, which should be detectable by the Planck satellite provided
systematic effects can be accounted for. Moreover, it is shown by fully
cosmological, hydro/gravity simulations that the formation of galactic discs is
only weakly affected by going from smooth to highly non-homogenous, initial
baryon distributions. In particular, the final disc angular momenta at z=0 are
as large as for the standard case and the ``disc angular momentum problem'' is
solved to within a factor of two or better without invoking (hypothetical)
energetic feedback events. A very desirable difference relative to the the
standard WDM model, however, is that the on-set of star (and AGN) formation
happens earlier. For the ``optimal'' free-streaming mass scale of M_f~1.5x10^11
h^-1 Msun the redshift of formation of the first stars increases from z_*=4-5
to >6.5, in much better agreement with observational data on high-redshift
galaxies and QSOs. It will, however, not be possible to push z_* above ~10,
because at higher redshifts the gas velocity field is nowhere compressive.
Probing the ``dark ages'' will hence enable a direct test of this theory.


title: Experimental implications of mirror matter-type dark matter

abstract:
  Mirror matter-type dark matter is one dark matter candidate which is
particularly well motivated from high energy physics. The theoretical
motivation and experimental evidence are pedagogically reviewed, with emphasis
on the implications of recent orthopositronium experiments, the DAMA/NaI dark
matter search, anomalous meteorite events etc.


title: The Newly Active R Coronae Borealis Star, V2552 Oph

abstract:
  In 2001, V2552 Oph (CD -22 12017, HadV98) quickly faded by several magnitudes
in a manner typical of the R Coronae Borealis (RCB) stars. Photometry of V2552
Oph obtained over 70 years previous to 2001 shows no indication of variability.
Optical spectra of this star subsequently confirmed that V2552 Oph is a member
of the hydrogen deficient, carbon-rich RCB class of variables. It resembles the
warm (T$_{eff}\sim$ 7000 K) RCB stars such as R Coronae Borealis itself. Other
RCB stars, such as XX Cam and Y Mus, have experienced similar periods of
inactivity, going decades without significant dust formation. Further
observations of V2552 Oph will be of great interest since there is an
opportunity to monitor an RCB star that may be moving from prolonged inactivity
into an active phase of dust production.


title: Dark Energy Constraints from Weak Lensing Cross-Correlation Cosmography

abstract:
  We present a method to implement the idea of Jain & Taylor to constrain
cosmological parameters with weak gravitational lensing. Photometric redshift
information on foreground galaxies is used to produce templates of the mass
structure at foreground slices z_\ell, and the predicted distortion field is
cross-correlated with the measured shapes of sources at redshift z_s. The
variation of the cross-correlation with z_s depends purely on ratios of angular
diameter distances. We propose a formalism for such an analysis that makes use
of all foreground-background redshift pairs, and derive the Fisher
uncertainties on the dark energy parameters that would result from such a
survey. Surveys from the proposed SNAP satellite or the LSST observatory could
constrain the dark energy equation of state to 0.01 f_sky^{-1/2} in w_0 and
0.035 f_sky^{-1/2} in w_a after application of a practical prior on \Omega_m.
Advantages of this method over power-spectrum measurements are that it is
unaffected by residual PSF distortions, is not limited by sample-variance, and
can use non-linear mass structures to constrain cosmology. The signal is,
however, very small, amounting to a change of a few parts in 10^3 of the
lensing distortion. The calibration of lensing distortion must be independent
of redshift to comparable levels, and photometric redshifts must be similarly
free of bias. Both of these tasks require substantial advance over the present
state of the art, but we discuss how such accurate calibrations might be
achieved using internal consistency tests. Elimination of redshift bias would
require spectroscopic redshifts of 10^4-10^5 high redshift galaxies.


title:
Optimal Galaxy Shape Measurements for Weak Lensing Applications Using
  the Hubble Space Telescope Advanced Camera for Surveys

abstract:
  We present three-epoch multiband ($V_{606}$, $i_{775}$, $z_{850}$)
measurements of galaxy shapes using the ``polar shapelet'' or
Laguerre-expansions method with the Hubble Space Telescope ($HST$) Advanced
Camera for Surveys (ACS) data, obtained as part of the {\it Great Observatories
Origin Deep Survey} (GOODS). We take advantage of the unique features of the
GOODS/ACS Fields to test the reliability of this relatively new method of
galaxy shape measurement for weak lensing analysis and to quantify the impact
of the ACS Point Spread Function (PSF) on $HST$/ACS data. We estimate the bias
introduced by the sharp PSF of the ACS on shape measurement. We show that the
bias in the tangential shear due to galaxy-galaxy lensing can be safely
neglected provided only well-resolved galaxies are used, while it would be
comparable to the signal level (1--3%) for cosmic shear measurements. These
results should of be general utility in planning and analyzing weak lensing
measurements with $HST$/ACS data.


title: The Most Detailed Picture Yet of an Embedded High-mass YSO

abstract:
  High-mass star formation is not well understood chiefly because examples are
deeply embedded, relatively distant, and crowded with sources of emission.
Using VLA and VLBA observations of water and SiO maser emission, we have mapped
in detail the structure and proper motion of material 20-500 AU from the
closest high-mass YSO, radio source-I in the Orion KL region. We observe
streams of material driven in a rotating, wide angle, bipolar wind from the
surface of an edge-on accretion disk. The example of source-I provides strong
evidence that high-mass star formation proceeds via accretion


title:
A Spectral Line Survey of Selected 3 mm Bands Toward Sagittarius
  B2(N-LMH) Using the NRAO 12 Meter Radio Telescope and the BIMA Array I. The
  Observational Data

abstract:
  We have initiated a spectral line survey, at a wavelength of 3 millimeters,
toward the hot molecular core Sagittarius B2(N-LMH). This is the first spectral
line survey of the Sgr B2(N) region utilizing data from both an interferometer
(BIMA Array) and a single-element radio telescope (NRAO 12 meter). In this
survey, covering 3.6 GHz in bandwidth, we detected 218 lines (97 identified
molecular transitions, 1 recombination line, and 120 unidentified transitions).
This yields a spectral line density (lines per 100 MHz) of 6.06, which is much
larger than any previous 3 mm line survey. We also present maps from the BIMA
Array that indicate that most highly saturated species (3 or more H atoms) are
products of grain chemistry or warm gas phase chemistry. Due to the nature of
this survey we are able to probe each spectral line on multiple spatial scales,
yielding information that could not be obtained by either instrument alone.


title:
On the photometric variability of blue supergiants in NGC 300 and its
  impact on the Flux-weighted Gravity-Luminosity Relationship

abstract:
  We present a study of the photometric variability of spectroscopically
confirmed supergiants in NGC 300, comprising 28 epochs extending over a period
of five months. We find 15 clearly photometrically variable blue supergiants in
a sample of nearly 70 such stars, showing maximum light amplitudes ranging from
0.08 to 0.23 magnitudes in the V band, and one variable red supergiant. We show
their light curves, and determine semi-periods for two A2 Ia stars. Assuming
that the observed changes correspond to similar variations in the bolometric
luminosity, we test for the influence of this variability on the Flux-weighted
Gravity--Luminosity Relationship and find a negligible effect, showing that the
calibration of this relationship, which has the potential to measure
extragalactic distances at the Cepheid accuracy level, is not affected by the
stellar photometric variability in any significant way.


title:
Beyond the Damping Tail: Cross-Correlating the Kinetic
  Sunyaev-Zel'dovich Effect with Cosmic Shear

abstract:
  Secondary anisotropies of the CMB have the potential to reveal intricate
details about the history of our universe between the present and recombination
epochs. However, because the CMB we observe is the projected sum of a multitude
of effects, the interpretation of small scale anisotropies by future high
resolution experiments will be marred by uncertainty and speculation without
the handles provided by other observations. In this paper we show that cross
correlating the CMB with an overlapping weak lensing survey will isolate the
elusive kinetic Sunyaev-Zel'dovich Effect from secondary anisotropies generated
at higher redshifts. We show that if upcoming high angular resolution CMB
experiments, like PLANCK/ACT/SPT, cover the same area of sky as current and
future weak lensing surveys, like CFTHLS/SNAP/LSST, the cross correlation of
cosmic shear with the kSZ effect will be detected with high signal to noise
ratio, increasing the potential science accessible to both sets of surveys. For
example, if ACT and a CFHTLS like survey were to overlap this cross-correlation
would be detected with a total signal to noise ratio greater than 220, reaching
1.8 per individual multipole around l \sim 5000. Furthermore, this
cross-correlation probes the three point coupling between the underlying dark
matter and the "momentum" of the ionized baryons in the densest regions of the
universe at intermediate redshifts. Similar to the tSZ power spectrum, its
strength is extremely sensitive to the power spectrum normalization parameter,
\sigma_8, scaling roughly as \sigma_8^7. It provides an effective mechanism to
isolate any component of anisotropy due to patchy reionization and rule out
primordial small scale anisotropy.


title: The Baryon Budget from BBN and the CBR

abstract:
  A key pillar of modern cosmology, Big Bang Nucleosynthesis (BBN) offers a
probe of the particle content and expansion rate of the Universe a mere few
minutes after the beginning. When compared with the BBN predictions, the
observationally inferred primordial abundances of deuterium and helium-4
provide an excellent baryometer and chronometer respectively. Several hundred
thousand years later, when the Cosmic Background Radiation (CBR) photons began
progagating freely, the spectrum of temperature fluctuations imprinted on them
also encoded information about the baryon density and the expansion rate.
Comparing the constraints imposed by BBN with those from the CBR reveals a
consistent picture of the Universe at these two very widely separated epochs.
Combining these probes leads to new, tighter constraints on the baryon density
at present and on possible new physics beyond the standard model of particle
physics.


title:
Star Formation History and Extinction in the central kpc of M82-like
  Starbursts

abstract:
  We report on the star formation histories and extinction in the central kpc
region of a sample of starburst galaxies that have similar far infrared (FIR),
10 micron and K-band luminosities as those of the archetype starburst M82. Our
study is based on new optical spectra and previously published K-band
photometric data, both sampling the same area around the nucleus. Model
starburst spectra were synthesized as a combination of stellar populations of
distinct ages formed over the Hubble time, and were fitted to the observed
optical spectra and K-band flux. The model is able to reproduce simultaneously
the equivalent widths of emission and absorption lines, the continuum fluxes
between 3500-7000 Ang, the K-band and the FIR flux. We require a minimum of 3
populations -- (1) a young population of age < 8 Myr, with its corresponding
nebular emission, (2) an intermediate-age population (age < 500 Myr), and (3)
an old population that forms part of the underlying disk or/and bulge
population. The contribution of the old population to the K-band luminosity
depends on the birthrate parameter and remains above 60% in the majority of the
sample galaxies. Even in the blue band, the intermediate age and old
populations contribute more than 40% of the total flux in all the cases. A
relatively high contribution from the old stars to the K-band nuclear flux is
also apparent from the strength of the 4000 Ang break and the CaII K line. The
extinction of the old population is found to be around half of that of the
young population. The contribution to the continuum from the relatively old
stars has the effect of diluting the emission equivalent widths below the
values expected for young bursts. The mean dilution factors are found to be 5
and 3 for the Halpha and Hbeta lines respectively.


title: Magnetorotational Instability in a Couette Flow of Plasma

abstract:
  All experiments, which have been proposed so far to model the
magnetorotational instability (MRI) in the laboratory, involve a Couette flow
of liquid metals in a rotating annulus. All liquid metals have small magnetic
Prandtl numbers, Pm, of about 10^{-6} (the ratio of kinematic viscosity to
magnetic diffusivity). With plasmas both large and small Pm are achievable by
varying the temperature and the density of plasma. Compressibility and fast
rotation of the plasma result in radial stratification of the equilibrium
plasma density. Evolution of perturbations in radially stratified viscous and
resistive plasma permeated by an axial uniform magnetic field is considered.
The differential rotation of the plasma is induced by the ExB drift in applied
radial electric field. Global unstable eigenmodes are calculated by our newly
developed matrix code. The plasma is shown to be MRI unstable for parameters
easily achievable in experimental setup.


title:
A model of an expanding giant that swallowed planets for the eruption of
  V838 Monocerotis

abstract:
  In early 2002 V838 Monocerotis had an extraordinary outburst whose nature is
still unclear. The optical light curve showed at least three peaks and imaging
revealed a light echo around the object - evidence for a dust shell which was
emitted several thousand years ago and now reflecting light from the eruption.
Spectral analysis suggests that the object was relatively cold throughout the
event, which was characterized by an expansion to extremely large radii. We
show that the three peaks in the light curve have a similar shape and thus it
seems likely that a certain phenomenon was three times repeated. Our suggestion
that the outburst was caused by the expansion of a red giant, followed by the
successive swallowing of three relatively massive planets in close orbits,
supplies a simple explanation to all observed peculiarities of this intriguing
object.


title: Clustering studies with the 2dF galaxy redshift survey

abstract:
  The 2dF Galaxy Redshift Survey has now been completed and has mapped the
three-dimensional distribution, and hence clustering, of galaxies in exquisite
detail over an unprecedentedly large ($\sim 10^{8} h^{-3}$ Mpc$^{3}$) volume of
the local Universe. Here we highlight some of the major results to come from
studies of clustering within the survey: galaxy correlation function and power
spectrum analyses and the constraints they have placed on cosmological
parameters; the luminosity functions of rich galaxy clusters, their dependence
on global cluster properties and galaxy type, and how they compare with the
field; and the variation of galactic star formation activity with environment,
both within clusters and in galaxy groups.


title:
An upper limit on the mass of galactic halo dark matter particles
  through the use of the Holographic principle

abstract:
  This paper was withdrawn by the authors due to serious flaws in the physics
that render the results meaningless.


title:
Detection of a Fully-resolved Compton Shoulder of the Iron K-alpha Line
  in the Chandra X-ray Spectrum of GX 301-2

abstract:
  We report the detection of a fully-resolved, Compton-scattered emission line
in the X-ray spectrum of the massive binary GX 301-2 obtained with the High
Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory.
The iron K-alpha fluorescence line complex observed in this system consists of
an intense narrow component centered at an energy of E = 6.40 keV and a redward
shoulder that extends down to ~6.24 keV, which corresponds to an energy shift
of a Compton back-scattered iron K-alpha photon. From detailed Monte Carlo
simulations and comparisons with the observed spectra, we are able to directly
constrain the physical properties of the scattering medium, including the
electron temperature and column density, as well as an estimate for the metal
abundance.


title:
The aperiodic timing behaviour of the accretion-driven millisecond
  pulsar SAX J1808.4-3658

abstract:
  We studied the aperiodic X-ray timing behaviour of the accreting millisecond
pulsar SAX J1808.4-3658. The source was recently found to be the first
accreting millisecond pulsar that shows the kilohertz quasi-periodic
oscillations (kilohertz QPOs) that are found in many other X-ray binaries with
accreting neutron stars. The high frequency of these signals reflects the short
dynamical time scales in the region near the compact object where they
originate. We find that in addition to the kilohertz QPOs SAX J1808.4-3658
shows several low frequency timing features, based on which the source can be
classified as a so-called atoll source. The frequencies of the variability
components of the atoll sources follow a universal scheme of correlations. The
correlations in SAX J1808.4-3658 are similar but show a shift in upper
kilohertz QPO frequency. This discrepancy is perhaps related to a stronger or
differently configured magnetic field.


title: Intrinsic spectral blueshifts in rapidly rotating stars?

abstract:
  Spectroscopic radial velocities for several nearby open clusters suggest that
spectra of (especially earlier-type) rapidly rotating stars are systematically
blueshifted by 3 km/s or more, relative to the spectra of slowly rotating ones.
Comparisons with astrometrically determined radial motions in the Hyades
suggests this to be an absolute blueshift, relative to wavelengths naively
expected from stellar radial motion and gravitational redshift. Analogous
trends are seen also in most other clusters studied (Pleiades, Coma Berenices,
Praesepe, Alpha Persei, IC 2391, NGC 6475, IC 4665, NGC 1976 and NGC 2516).
Possible mechanisms are discussed, including photospheric convection, stellar
pulsation, meridional circulation, and shock-wave propagation, as well as
effects caused by template mismatch in determining wavelength displacements.
For early-type stars, a plausible mechanism is shock-wave propagation upward
through the photospheric line-forming regions. Such wavelength shifts thus
permit studies of certain types of stellar atmospheric dynamics and -
irrespective of their cause - may influence deduced open-cluster membership
(when selected from common velocity) and deduced cluster dynamics (some types
of stars might show fortuitous velocity patterns).


title: An observational review of accretion-driven millisecond X-ray pulsars

abstract:
  I present an observational review of the five currently known
accretion-driven millisecond X-ray pulsars. A prominent place in this review is
given to SAX J1808.4-3658; it was the first such system discovered and
currently four outbursts have been observed from this source. This makes SAX
J1808.4-3658 the best studied example of the group. Its most recent outburst in
October 2002 is of particular interest because of the discovery of two
simultaneous kilohertz quasi-periodic oscillations and nearly coherent
oscillations during type-I X-ray bursts. This is the first time that such
phenomena are observed in a system for which the neutron star spin frequency is
exactly known. The other four systems were discovered within the last two years
and only limited results have been published. Since new exiting results are to
be expected in the future for all five sources, this review will only represent
a snap-shot of the current observational knowledge of accretion-driven
millisecond X-ray pulsars. A more extended and fully up-to-date review can be
found at http://zon.wins.uva.nl/~rudy/admxp/.


title: Efficiency of convection and pre-mainsequence lithium depletion

abstract:
  We show by detailed model computation how much the Pre-Main Sequence (PMS)
Lithium depletion depends on the treatment of over-adiabaticity, by taking
advantage of the results of new models by Montalb\'an et al., which apply
different treatments of convection to non-grey PMS models. In order to
reproduce both the PMS lithium depletion (inferred from the lithium depletion
patterns in young open clusters), and the location of PMS tracks in the HR
diagram (inferred from the study of young PMS stars), convection both in the
atmosphere and in a good fraction of the stellar envelope must be highly
inefficient: e.g., in the Mixing Length Theory approximation, it must have a
very low alpha=l/H_p. Unfortunately, the radii of these models are at variance
with the solar radius, possibly indicating t hat there is some additional
physical input, generally not taken into account in the stellar models, which
affects the efficiency of convection in PMS stars, but probably not in the main
sequence stars nor in evolved red giants. We stress the importance of
determining precisely masses and lithium abundance in PMS binaries such as the
important spectroscopic and eclipsing binary RXJ0529.4+0041.