title:
Rotation of Jets from Young Stars: New Clues from the Hubble Space
  Telescope Imaging Spectrograph

abstract:
  We report findings from the first set of data in a current survey to
establish conclusively whether jets from young stars rotate. We observed the
bi-polar jets from the T Tauri stars TH28 and RW Aur, and the blue-shifted jet
from T Tauri star LkH$\alpha$321, using the Hubble Space Telescope Imaging
Spectrograph (HST/STIS). Forbidden emission lines (FELs) show distinct and
systematic velocity asymmetries of 10 -- 25 (+/- 5) km/s at a distance of 0".3
from the source, representing a (projected) distance of ~ 40 AU along the jet
in the case of RW Aur, ~ 50 AU for TH28, and 165 AU in the case of
LkH$\alpha$321. These velocity asymmetries are interpreted as rotation in the
initial portion of the jet where it is accelerated and collimated. For the
bi-polar jets, both lobes appear to rotate in the same direction. Values
obtained were in agreement with the predictions of MHD disk-wind models
(Bacciotti et al 2002, Anderson et al 2003, Dougados et al 2003, Pesenti et al
2003). Finally, we determine, from derived toroidal and poloidal velocities,
values for the distance from the central axis of the footpoint for the jet's
low velocity component of ~ 0.5 - 2 AU, consistent with the models of
magneto-centrifugal launching (Anderson et al 2003).


title: Triangulating Radiation: Radiative Transfer on Unstructured Grids

abstract:
  We present a new numerical approach that is able to solve the
multi-dimensional radiative transfer equations in all opacity regimes on a
Lagrangian, unstructured network of characteristics based on a stochastic point
process. Our method reverses the limiting procedure used to derive the transfer
equations, by going back to the original Markov process. Thus, we reduce this
highly complex system of coupled differential equations to a simple
one-dimensional random walk on a graph, which is shown to be computationally
very efficient. Specifically, we use a Delaunay graph, which makes it possible
to combine our scheme with a new smoothed particle hydrodynamics (SPH) variant
proposed by Pelupessy et al.(2003). We show that the results of applying a
two-dimensional implementation of our method with various suitable test cases
agree with the analytical results, and we point out the advantages of using our
method with inhomogeneous point distributions, showing examples in the
progress. Hereafter, we present a supplement to our method, which can be useful
in cases where the medium is optically very thin, and we conclude by stating
some anticipated properties of this method in three dimensions, and announce
future extensions.


title: The role of nova nucleosynthesis in Galactic chemical evolution

abstract:
  In this paper we study the impact of nova nucleosynthesis on models for the
chemical evolution of the Galaxy. It is found that novae are likely to be the
sources of non-negligible fractions of the 7Li and 13C observed in disc stars.
Moreover, they might be responsible for the production of important amounts of
17O at late times and probably account for a major fraction of the Galactic
15N.


title:
A Strong Test of Electro-Weak Theory using Pulsating DB White Dwarf
  Stars as Plasmon Neutrino Detectors

abstract:
  We demonstrate that plasmon neutrinos are the dominant form of energy loss in
model white dwarf stars down to T_eff ~ 25,000 K, depending on the stellar
mass. The lower end of this range overlaps the observed temperatures for the
V777 Her star (DBV) instability strip. The evolution of white dwarfs at these
temperatures is driven predominantly by cooling, so this directly affects the
stellar evolutionary timescale in proportion to the ratio of the neutrino
energy loss to the photon energy loss. This evolutionary timescale is
observable through the time rate of change of the pulsation periods. Although
the unified electro-weak theory of lepton interactions that is crucial for
understanding neutrino production has been well tested in the high energy
regime, the approach presented here should result in an interesting low-energy
test of the theory. We discuss observational strategies to achieve this goal.


title: Newly Discovered Globular Clusters in the Outer Halo of M31

abstract:
  We present nine newly discovered globular clusters in the outer halo of M31,
found by a semi-automated procedure from a INT Wide Field Camera survey of the
region. The sample includes a candidate at the yet largest known projected
galactocentric radius from M31.


title:
Is there a common origin for the WMAP low multipole and for the
  ellipticity in BOOMERanG CMB maps?

abstract:
  We have measured the ellipticity of several degree scale anisotropies in the
BOOMERanG maps of the Cosmic Microwave Background (CMB) at 150 GHz. The average
ellipticity is around 2.6-2.7. The biases of the estimator of the ellipticity
and for the noise are small in this case. Large spot elongation had been
detected also for COBE-DMR maps. If this effect is due to geodesic mixing, it
would indicate a non precisely zero curvature of the Universe which is among
the discussed reasons of the WMAP low multipole anomaly. Both effects are
related to the diameter of the Universe: the geodesics mixing through
hyperbolic geometry, low multipoles through boundary conditions.This common
reason can also be related with the origin of the the cosmological constant:
the modes of vacuum fluctuations conditioned by the boundary conditions lead to
a value of the cosmological constant being in remarkable agreement with the
supernovae observations.


title: Gamma-Ray Bursts: their Sources

abstract:
  My conviction is explained that none of the daily gamma-ray bursts comes from
cosmic distances. In particular, nearby reflection nebulae have been mistaken
for host galaxies.


title:
On the reliability of the black hole mass and mass to light ratio
  determinations with Schwarzschild models

abstract:
  In this Letter, we investigate the claim of Valluri et al. (2003), namely
that the use of Schwarzschild dynamical (orbit-based) models leads to an
indeterminacy regarding the estimation of the free parameters like the central
black hole mass and the stellar mass-to-light ratio of the galaxy under study.
We examine this issue with semi-analytic two-integral models, which are not
affected by the intrinsic degeneracy of three-integral systems. We however
confirm the Valluri et al. result, and observe the so-called widening of the
chi2 contours as the orbit library is expanded. We also show that, although
two-dimensional data coverage help in constraining the orbital structure of the
modelled galaxy, it does not in principle solve the indeterminacy issue, which
mostly originates from the discretization of such an inverse problem. We show
that adding regularization constraints stabilizes the confidence level contours
on which the estimation of black hole mass and stellar mass-to-light ratio are
based. We therefore propose to systematically use regularization as a tool to
prevent the solution to depend on the orbit library. Regularization, however,
introduces an unavoidable bias on the derived solutions. We hope that the
present Letter will trigger some more research directed at a better
understanding of the issues addressed here.


title:
On the evolution of the cosmic-mass-density contrast and the
  cosmological constant

abstract:
  We study the evolution of the cosmic-mass-density contrast beyond the
Robertson-Walker geometry including the small contribution of acceleration. We
derive a second-order evolution equation for the density contrast within the
spherical model for CDM collisionless fluid including the cosmological
constant, the expansion and the non-vanishing vector of acceleration. While the
mass-density is not seriously affected by acceleration, the mass-density
contrast changes its shape at smaller redshifts even for a small amount of the
acceleration parameter. This could help to resolve current controversial
results in cosmology from measurements of WMAP, gravitational lensing, XMM
X-ray cluster or type Ia supernovae data, etc.


title:
Anisotropy of Magnetohydrodynamic Turbulence and the Polarized Spectra
  of OH Masers

abstract:
  We consider astrophysical maser radiation that is created in the presence of
mildly supersonic, magnetohydrodynamic (MHD) turbulence. The focus is on the OH
masers for which the magnetic field is strong enough that the separations of
the Zeeman components are greater than the spectral linebreadths. A
longstanding puzzle has been the absence of the Zeeman $\pi $ components and
the high circular polarization in the observed spectra of these masers. We
first argue that the elongation of eddies along the field that has recently
been recognized in MHD turbulence will enhance the optical depth parallel to
the magnetic field in comparison with that perpendicular to the magnetic field.
We then simulate maser emission with a numerical model of MHD turbulence to
demonstrate quantitatively how the intensities of the linearly polarized $\pi $
components are suppressed and the intensities of the nearly circularly
polarized $\sigma $ components are enhanced. This effect is also generic in the
sense that most spectral lines in MHD turbulence with Mach number $M\sim 1$
should have larger optical depths parallel to the magnetic field than
perpendicular. The effect is reduced considerably when $M<1$. The simulations
also demonstrate that the velocity and magnetic field variations due to the
turbulence can (but do not necessarily) cause one of the $\sigma $ components
to be much more intense than the other, as is often observed for mainline OH
masers.


title: Determining Accurate Distances to Nearby Galaxies

abstract:
  We have undertaken several projects with the purpose of determining accurate
distances to nearby galaxies to calibrate the extragalactic distance scale.
Specifically, I describe the DIRECT project which aims to derive the distance
to M31 and M33 directly, using detached eclipsing binaries and the
Baade-Wesselink method for Cepheids. I also present a ``hybrid'' method of
discovering Cepheids with ground-based telescopes using image subtraction and
then following them up with the HST to derive Cepheid period-luminosity
distances.


title: Photometric variability of the unique magnetic white dwarf GD356

abstract:
  GD356 is a magnetic white dwarf (B = 13MG) that uniquely displays weak
resolved Zeeman triplets of Halpha and Hbeta in emission. As such, GD356 may be
the only known white dwarf with some kind of chromosphere, although accretion
from the interstellar medium or more exotic mechanisms cannot be ruled out.
Here, we report the detection of low amplitude (+/-~0.2%) near-sinusoidal
photometric (V-band) variability in GD356, with a period of 0.0803 days (~115
minutes). We interpret this as the rotation period of the star. We model the
variability with a dark spot (by analogy with star spots) covering 10% of the
stellar surface. It seems likely that this spot is also the site of the Zeeman
emission, requiring the presence of a temperature inversion. We show that the
spot is never totally visible or obscured, and that both polar and equatorial
spots produce good fits to the data when viewed at high and low inclination
respectively.


title: Well-proportioned universes suppress CMB quadrupole

abstract:
  A widespread myth asserts that all small universe models suppress the CMB
quadrupole. In actual fact, some models suppress the quadrupole while others
elevate it, according to whether their low-order modes are weak or strong
relative to their high-order modes. Elementary geometrical reasoning shows that
a model's largest dimension determines the rough value ell_min at which the CMB
power spectrum ell(ell + 1)C_ell/(2pi) effectively begins; for cosmologically
relevant models, ell_min < 4. More surprisingly, elementary geometrical
reasoning shows that further reduction of a model's smaller dimensions -- with
its largest dimension held fixed -- serves to elevate modes in the neighborhood
of ell_min relative to the high-ell portion of the spectrum, rather than
suppressing them as one might naively expect. Thus among the models whose
largest dimension is comparable to or less than the horizon diameter, the
low-order C_ell tend to be relatively weak in well-proportioned spaces (spaces
whose dimensions are approximately equal in all directions) but relatively
strong in oddly-proportioned spaces (spaces that are significantly longer in
some directions and shorter in others). We illustrate this principle in detail
for the special cases of rectangular 3-tori and spherical spaces. We conclude
that well-proportioned spaces make the best candidates for a topological
explanation of the low CMB quadrupole observed by COBE and WMAP.


title: Testing Bimodal Planet Formation

abstract:
  We suggest that the observed break in giant-planet frequency as a function of
host metallicity at Z=0.02 may be a reflection of bimodal planet formation. We
search for signatures of this bimodality in the distributions of the planet
eccentricities, periods, masses, and multiplicity. However, the low-metallicity
sample is at present too small to test for any but the most severe differences
in these two putative populations.


title: GRBlog: A Database for Gamma-Ray Bursts

abstract:
  GRBlog is an on-line database providing researchers with quick access to all
information reported in the GCN Circulars. Users of the GRBlog web site
(grad40.as.utexas.edu/grblog.php) can search the circulars and produce
afterglow light curve plots, or compile data tables. The site also offers
advanced search capabilities to aide in statistical studies or comparative
research. Most of the GCNs have already been entered into the GRBlog database,
with the remainder to follow shortly.


title: The Chemical Inhomogeneity of Faint M13 Stars: C and N Abundances

abstract:
  Building upon earlier observations which demonstrate substantial star-to-star
differences in the carbon abundances of M13 subgiants, we present new Keck LRIS
spectra reaching more that 1.5 mag below the M13 main-sequence turn-off (to V ~
20). Our analysis reveals a distribution of C abundances similar to that found
among the subgiants, implying little change in the compositions of the M13
stars at least through the main-sequence turn-off. We presume these differences
to be the result of some process operating early in the cluster history.
  Additional spectra of previously studied bright M13 giants have been obtained
with the Hale 5-m. A comparison of C abundances derived using the present
methods and those from the literature yield a mean difference of 0.03+-0.14 dex
for four stars in common with Smith et al. (1996) and 0.14+-0.07 dex for stars
also observed by Suntzeff (1981) (if one extreme case is removed). We conclude
that the lower surface C abundances of these luminous giants as compared to the
subgiants and main-sequence stars are likely the result of mixing rather than a
difference in our abundance scales.
  NH band strengths have also been measured for a handful of the most luminous
M13 turn-off stars. While molecular band formation in such stars is weak,
significant star-to-star NH band strength differences are present. Moreover,
for the stars with both C and N measurements, differences between stars in
these two elements appear to be anticorrelated.
  Finally, the most recent C and N abundances for main-sequence, main-sequence
turn-off, and subgiant stars in 47 Tuc, M71, M5, and the present M13 data are
compared.


title: On the C and N Abundances of 47 Tucanae Main Sequence Stars

abstract:
  We report the results of an analysis of CN and CH band strengths among a
large sample of 47 Tucanae main-sequence and turn-off stars presented earlier
by Harbeck et al. The resulting C and N abundances derived from synthetic
spectra demonstrate:
  1) A strongly anti-correlated relationship between [C/Fe] and [N/Fe] with the
CN-strong stars exhibiting depleted carbon and enhanced nitrogen.
  2) The abundances of both elements agree remarkably well with those found
among the evolved red giants of the cluster implying little change in surface
abundances from at least Mv ~ +6.5 to the tip of the red giant branch.
  3) The pattern of C-depletions and N-enhancements are quite similar to those
seen among the turn-off stars of M71, a cluster of almost identical metallicity
but lower central concentration and escape velocity. At the same time, similar
if not smaller N-enhancements and larger C-depletions are evident among like
stars in the more metal-poor cluster M5.
  We interpret these results, as did Harbeck et al., as evidence of the
operation of some pollution/accretion event early in the cluster history - the
most likely source being AGB ejecta. However, the present results rule out
simple surface pollution and suggest that a substantial fraction of the present
stars' masses must be involved.


title:
The Millennium Galaxy Catalogue: The photometric accuracy, completeness
  and contamination of the 2dFGRS and SDSS-EDR & DR1 datasets

abstract:
  The Millennium Galaxy Catalogue (MGC) is a deep ($\mu_{\rm B,lim}=26$ mag
arcsec$^{-2}$), wide field CCD imaging survey, covering 37.5deg$^2$ and is
completely contained within the 2dFGRS and SDSS-EDR. We compare the photometry
and completeness of the 2dFGRS and the SDSS-EDR with the MGC. We have also
undertaken a photometric comparison to SCOS and SDSS-DR1 data.
  We find that $B_{MGC}-B_{2dF}=0.035$ mag with an uncertainty of 0.142 mag per
galaxy, $B_{MGC}-B_{SCOS}=0.032$ mag with an uncertainty of 0.108 mag,
$B_{MGC}-B_{SDSS-EDR}=0.032$ mag with an uncertainty of 0.094 mag, and
$B_{MGC}-B_{SDSS-DR1}=0.039$ mag with an uncertainty of 0.086 mag. We find that
high surface brightness 2dFGRS galaxies are systematically too faint. In the
SDSS there is a weak non-linear scale error, which is negligible for faint
galaxies. LSBGs in the SDSS are systematically fainter.
  We find that the 2dFGRS catalogue has 5.2% stellar contamination, 7.0% of
objects are resolved into 2 or more by the MGC and is 8.7% incomplete compared
to the MGC. From our all object spectroscopic survey we find that the MGC is
itself misclassifying 5.6% of galaxies as stars, hence the 2dFGRS misses 14.3%
of the galaxies. The SDSS-EDR galaxy catalogue has 1.3% stellar contamination
and 5.3% of galaxies misclassified as stars, and is 1.8% incomplete compared to
the MGC. Altogether 7.1% of the total galaxy population are missing from the
SDSS-EDR catalogue from incompleteness or misclassification.


title: 3D Relativistic SPH

abstract:
  In this paper we present the equations and some basic applications of
relativistic SPH. The equations are generated under the assumption that there
are no interaction terms between the fluid modelled and the background
space-time, i.e. we are neglecting the perturbations to the metric produced by
the modelled fluid. This corresponds to a stationary metric, which for this
work, we further limit to be static as well. The equations use a new signal
velocity term and artificial viscosity to smear out the effects of strong
shocks and are tested here against Newtonian and relativistic shocks.


title: MHD simulations of the collapsar model for GRBs

abstract:
  We present results from axisymmetric, time-dependent magnetohydrodynamic
(MHD) simulations of the collapsar model for gamma-ray bursts. Our main
conclusion is that, within the collapsar model, MHD effects alone are able to
launch, accelerate and sustain a strong polar outflow. We also find that the
outflow is Poynting flux-dominated, and note that this provides favorable
initial conditions for the subsequent production of a baryon-poor fireball.


title: 350 micron observations of local IRAS galaxies using SHARC-II

abstract:
  The cosmologically significant population of dusty galaxies detected at
sub-mm and mm wavelengths by SCUBA and MAMBO have played a central part in many
of the discussions at this workshop. Obtaining their redshifts is critical in
understanding their role in galaxy formation and evolution, but this is a
challenging task. Significant progress has been made by obtaining spectroscopic
redshifts of the subset of sub-mm galaxies detected in deep radio images, but
other groups advocate a photometric redshift approach. Such methods rely on
understanding the Spectral Energy Distribution of the galaxies under study, but
these are not well characterized for even the well-studied nearby Infrared
luminous population. Observations at short sub-mm wavelengths, previously
difficult until the commissioning of SHARC-II at the CSO, can be used to better
constrain the dust properties of these galaxies.


title: Galaxy Evolution in Three dimensions : Time, Space and Mass

abstract:
  There are three major axes to describe the evolution of galaxies, namely,
time (redshift), space (environment) and mass (stellar mass). In this article,
one topic each will be presented along these axes. (1) Based on the Subaru
wide-field (30') optical imaging of two distant clusters (z=0.55 and 0.83), we
show the large scale structures in galaxy distributions on a scale greater than
10Mpc, which serve as an evidence for hierarchical growth of rich clusters of
galaxies through assembly of surrounding groups. (2) Based on the deep NIR
imaging of high-z clusters at z~1 and 1.5, we show massive galaxies in clusters
have assembled most of their mass by z=1.5, which is earlier than the
hierarchical model predictions. (3) Based on the Subaru deep and wide optical
imaging of Subaru/XMM-Newton Deep Survey Field, we show a deficit of red and
faint galaxies and a lack of blue massive galaxies in the high density regions
at z~1, which suggest down-sizing in galaxy formation as apparently opposed to
the CDM-based bottom-up scenario.


title:
Chandra Observations of NGC 4438: An Environmentally Damaged Galaxy in
  the Virgo Cluster

abstract:
  We present results from a 25 ksec CHANDRA ACIS-S observation of galaxies
NGC4438 and NGC4435 in the Virgo Cluster. X-ray emission in NGC4438 is observed
in a ~700 pc nuclear region, a 2.3 kpc spherical bulge, and a network of
filaments extending 4-10 kpc to the W and SW of the galaxy. The X-ray emission
in all 3 regions is highly correlated to similar features observed in Halpha.
Spectra of the filaments and bulge are well represented by a 0.4 keV MEKAL
model with combined 0.3-2 keV intrinsic luminosity of 1.24x10^{40}erg/s,
electron densities ~ 0.02-0.04 cm^{-3}, cooling times of 400-700 Myr and X-ray
gas mass <~ 3.7x10^8 Msolar. In the nuclear region of NGC4438 X-ray emission is
seen from the nucleus and from two outflow bubbles extending 360(730) pc to the
NW(SE) of the nucleus. The spectrum of the NW outflow bubble plus nucleus is
well fitted by an absorbed (n_H=1.9x10^{21} cm^{-2}) 0.58 keV MEKAL plasma
model plus a heavily absorbed (n_H = 2.9 x10^{22} cm^{-2}) Gamma = 2, power law
component. The electron density, cooling time, and X-ray gas mass in the NW
outflow are ~0.5 cm^{-3}, 30 Myr and 3.5x10^6 Msolar. Weak X-ray emission is
observed in the central region of NGC4435 with the peak of the hard emission
coincident with the galaxy's optical center; while the peak of the soft X-ray
emission is displaced 316 pc to the NE. The spectrum of NGC 4435 is well fitted
by a non-thermal power law plus a thermal component from 0.2-0.3 keV diffuse
ISM gas. We argue that the X-ray properties of gas outside the nuclear region
in NGC4438 and in NGC4435 favor a high velocity, off-center collision between
these galaxies ~ 100 Myr ago; while the nuclear X-ray emitting outflow gas in
NGC4438 has been heated only recently (within ~ 1-2 Myr) by shocks (v_s ~ 600
kms^{-1}) possibly powered by a central AGN.


title: The WSRT wide-field HI survey: II. Local Group features

abstract:
  We have used the WSRT to carry out an unbiased wide-field survey of HI
emission features, achieving an RMS sensitivity of about 18 mJy/Beam at a
velocity resolution of 17 km/s over 1800 deg^2. In this paper we present our HI
detections at negative velocities which could be distinguished from the
Galactic foreground. Fully 29% of the entire survey area has high velocity HI
emission with N_HI exceeding our 3 sigma limit of about 1.5x10^17cm^-2 over 30
km/s. A faint population of discrete HVCs is detected in the immediate vicinity
of M31 which spans a large fraction of the M31 rotation velocity. This class of
features is confined to about 12 deg (160 kpc) projected radius of M31 and
appears to be physically associated. We detect a diffuse northern extension of
the Magellanic Stream (MS) from at least Dec=+20 to +40 deg., which then loops
back toward the south. Recent numerical simulations had predicted just such an
MS extension corresponding to the apo-galacticon portion of the LMC/SMC orbit
at a distance of 125 kpc. A faint bridge of HI emission appears to join the
systemic velocities of M31 with that of M33 and continues beyond M31 to the
north-west. This may be the first detection of HI associated with the warm-hot
intergalactic medium (WHIM). The distribution of peculiar velocity HI
associated with M31 can be described by a projected exponential of 25 kpc
scale-length and 5x10^17cm^-2 peak column density. We present the distribution
function of N_HI in the extended M31 environment, which agrees well with the
low red-shift QSO absorption line data over the range log(N_HI)=17.2 to 21.9.
Our data extend this comparison about two orders of magnitude lower than
previously possible and provide the first image of the Lyman limit absorption
system associated with an L* galaxy. (abridged)


title: The Chandra Deep Field South: Optical Spectroscopy I

abstract:
  We present the results of our spectroscopic follow-up program of the X-ray
sources detected in the 942 ks exposure of the Chandra Deep Field South (CDFS).
288 possible counterparts were observed at the VLT with the FORS1/FORS2
spectrographs for 251 of the 349 Chandra sources (including three additional
faint X-ray sources). Spectra and R-band images are shown for all the observed
sources and R-K colours are given for most of them. Spectroscopic redshifts
were obtained for 168 X-ray sources, of which 137 have both reliable optical
identification and redshift estimate (including 16 external identifications).
The R<24 observed sample comprises 161 X-ray objects (181 optical counterparts)
and 126 of them have unambiguous spectroscopic identification. We introduce a
new classification based solely on X-ray properties, HR and X-ray luminosity,
consistent with the unified AGN model. This X-ray classification uncovers a
large fraction of optically obscured, X-ray luminous AGNs missed by the
classical optical classification.


title:
The Effect of Radiative Feedback on Bondi--Hoyle Flow around a Massive
  Star

abstract:
  We apply an algorithm for radiative feedback on a dusty flow (detailed in
Edgar and Clarke (2003)) to the problem of Bondi--Hoyle accretion. This
calculation is potentially relevant to the formation of massive stars in
ultradense cores of stellar clusters. We find that radiative feedback is
\emph{more effective} than in the case of previous calculations in spherical
symmetry. The Bondi-Hoyle geometry implies that material is flowing nearly
tangentially when it experiences the sharp radiative impulse at the dust
destruction radius, and consequently it is readily perturbed into outflowing
orbits. We find that it is difficult for stellar masses to grow beyond around
10 M_sol (for standard interstellar dust abundances). We discuss the possible
implications of this result for the formation mechanism of OB stars in cluster
cores. We end by proposing a series of conditions which must be fulfilled if
Bondi--Hoyle accretion is to continue.


abstract:
  X-ray observations of middle-aged pulsars allow one to study nonthermal
radiation from pulsar magnetospheres and thermal radiation from neutron star
(NS) surfaces. In particular, from the analysis of thermal radiation one can
infer the surface temperatures and radii of NSs, which is important for
investigating evolution of these objects and constraining the equation of state
of the superdense matter in the NS interiors. Here we present results of XMM
observations of three middle-aged pulsars, J0538+2817, B0656+14 and J0633+1746
(Geminga), and briefly discuss mechanisms of their X-ray emission.


title: Modification of Dust Grain Structure by Sputtering

abstract:
  We have applied the SRIM computer code to study the sputtering of some likely
astrophysical grain materials, and we have shown that selective embedding of
metallic projectiles offers a partial explanation of gas-phase depletions. We
show that supernova shockwaves sweep a significantly larger mass of
interstellar gas per unit time than the shockwaves generated by outflows in
star-forming regions. We apply our sputtering model to the bombardment levels
expected in a supernova shock, and show that net embedding may dominate over
net sputtering, leading to grain growth under some circumstances, particularly
when the bombarding gas is enriched with metals from the supernova progenitor
star. A combination of short cooling times and net embedding mean that it is
possible for a type II supernova to generate more dust that it destroys, and we
conclude that, in general, the sputtering process often leads to a
compositional change in the grain material rather than simply to grain erosion.


title: Revealing the obscured supernova remnant Kes 32 with Chandra

abstract:
  I report here on the analysis and interpretation of a Chandra observation of
the supernova remnant Kes 32. Kes 32 is rather weak in X-rays due to a large
interstellar absorption, which is found to be ~4E22 cm^-2, larger than
previously reported. Spectral analysis indicates that the ionization age of
this object is very young, with n_e t ~ 4E9 cm^-3s, and a temperature of kT_e ~
1 keV. The X-ray emission peaks at a smaller radius than in the radio. The low
ionization age suggests that Kes 32 is a young remnant. However, a young age is
in contradiction with the relatively large apparent size, which indicates an
age of several thousand years, instead of a few hundred years. This problem is
discussed in connection with Kes 32's unknown distance and its possible
association with the Norma galactic arm.


title: Coronal stripping in supersaturated stars

abstract:
  A recent unambiguous detection of X-ray rotational modulation of the
supersaturated star VXR45 (P = 0.223 days) has shown that its corona has
discrete dark and bright X-ray regions. We suggest that due to the rapid
rotation, the X-ray emitting corona has been centrifugally stripped away,
creating open field regions that are dark in X-rays. This leads naturally both
to a significant rotational modulation in X-rays but also to the lower X-ray
luminosity of supersaturated stars compared to those rotating more slowly. To
demonstrate the effect, we take as an example a more slowly rotating star for
which surface magnetograms are available. We extrapolate the potential coronal
magnetic field based on these magnetograms and determine for a hydrostatic,
isothermal atmosphere the structure of the density and of the optically-thin
X-ray emission. We show that if the rotation rate of this star were increased,
the magnitude of the X-ray luminosity would decrease while its rotational
modulation would increase in a way that is consistent with the recent
observations of VXR45.


title:
Heavy quarks or compactified extra dimensions in the core of hybrid
  stars

abstract:
  Neutron stars with extremely high central energy density are natural
laboratories to investigate the appearance and the properties of compactified
extra dimensions with small compactification radius, if they exist. Using the
same formalism, these exotic hybrid stars can be described as neutron stars
with quark core, where the high energy density allows the presence of heavy
quarks (c, b, t). We compare the two scenarios for hybrid stars and display
their characteristic features.


title:
Linear polarization on Gamma-Ray Bursts: from the prompt to the late
  afterglow

abstract:
  The past year has witnessed a large increase in our knowledge of the
polarization properties of Gamma-Ray Burst (GRB) radiation. In the prompt
phase, the measurement (albeit highly debated) of a large degree of linear
polarization in GRB 021206 has stimulated a deep theoretical study of
polarization from GRB jets. The optical afterglow of GRB 030329, on the other
hand, has been followed thoroughly in polarimetric mode, allowing for an
unprecedented sampling of its polarization curve. I will review the present
status of theories and observations of polarization in GRBs, focusing on how
polarimetric observations and their modelling can give us informations on the
structure and magnetisation o GRB jets which is not possible to obtain from
their light curve.


title: The inner structure of hybrid stars

abstract:
  Hybrid stars with extremely high central energy density in their core are
natural laboratories to investigate the appearance and the properties of
compactified extra dimensions with small compactification radius -- if these
extra dimensions exist at all. We introduce the necessary formalism to describe
quantitatively these objects and the properties of the formed hydrostatic
equilibrium. Different scenarios of the extra dimensions are discussed and the
characteristic features of these hybrid stars are calculated.


title: ISO observations of four active galaxies

abstract:
  We present ISO PHOT-S spectra of four galaxies known or suspected to host a
central AGN, selected from the initial Iras/Rosat sample of Boller et al.
(1992). Two of them had no obvious Seyfert features in their previous optical
spectra: IRAS 14201+2956, and IRAS 21582+1018. The latter was bright enough to
also allow SWS observations around selected neon lines, to establish its
excitation. While both PHOT-S spectra are characteristic of starburst-dominated
galaxies, the neon line ratios in IRAS 21582+1018 indicate the presence of a
hard excitation source. New, high-resolution, optical spectra show only a weak,
broad component around Halpha, classifying now these two objects as Sey 1.9
galaxies. The two other galaxies observed are the NLS1 galaxies Mrk 359 and Mrk
1388. Their ISO spectra however do not reveal the typical, strong PAH features
found in the starburst galaxies and are more like those of standard Seyferts.
These results show therefore that, although IR observations were expected to be
able to always reveal the presence of an active nucleus by piercing through the
central obscuration, the result may be ambiguous: the broad band IR energy
distribution can still be dominated by starburts located in a circumnuclear
region, and the AGN appear only in specific observations (high-excitation lines
in the IR, or optical spectra with better quality than classification spectra).
The obscuration needs however to be patchy rather than complete, to explain the
detection of the high-excitation lines or broad Balmer wings. Only high-energy
observations can then establish the strength of the central
  AGN and the amount of extinction with certainty.


title: Burst Populations and Detector Sensitivity

abstract:
  The F_T (peak bolometric photon flux) vs. E_p (peak energy) plane is a
powerful tool to compare the burst populations detected by different detectors.
Detector sensitivity curves in this plane demonstrate which burst populations
the detectors will detect. For example, future CZT-based detectors will show
the largest increase in sensitivity for soft bursts, and will be particularly
well-suited to study X-ray rich bursts and X-ray Flashes. Identical bursts at
different redshifts describe a track in the F_T-E_p plane.


title: GLAST's GBM Burst Trigger

abstract:
  The GLAST Burst Monitor (GBM) will detect and localize bursts for the GLAST
mission, and provide the spectral and temporal context in the traditional 10
keV to 25 MeV band for the high energy observations by the Large Area Telescope
(LAT). The GBM will use traditional rate triggers in up to three energy bands,
and on a variety of timescales between 16 ms and 16 s.


title: Burst Statistics Using the Lag-Luminosity Relationship

abstract:
  Using the lag-luminosity relation and various BATSE catalogs we create a
large catalog of burst redshifts, peak luminosities and emitted energies. These
catalogs permit us to evaluate the lag-luminosity relation, and to study the
burst energy distribution. We find that this distribution can be described as a
power law with an index of alpha=1.76 +/- 0.05 (95% confidence), close to the
alpha=2 predicted by the original quasi-universal jet model.


title: Analysis of Burst Observations by GLAST's LAT Detector

abstract:
  Analyzing data from GLAST's Large Area Telescope (LAT) will require
sophisticated techniques. The PSF and effective area are functions of both
photon energy and the position in the field-of-view. During most of the mission
the observatory will survey the sky continuously and thus the LAT will detect
each count from a source at a different detector orientation; each count
requires its own response function! The likelihood as a function of celestial
position and photon energy will be the foundation of the standard analysis
techniques. However the 20 MeV-300 GeV emission at the time of the ~100 keV
burst emission (timescale of ~10 s) can be isolated and analyzed because
essentially no non-burst counts are expected within a PSF radius of the burst
location during the burst. Both binned and unbinned (in energy) spectral
fitting will be possible. Longer timescale afterglow emission will require the
likelihood analysis that will be used for persistent sources.


title:
The Structure and Environment of Young Stellar Clusters in Spiral
  Galaxies

abstract:
  A search for stellar clusters has been carried out in 18 nearby spiral
galaxies, using HST/WFPC2 archive images. All of the galaxies have previously
been imaged from the ground in UBVI. A catalogue of structural parameters,
photometry and comments based on visual inspection of the clusters is compiled
and used to investigate correlations between cluster structure, environment,
age and mass. Least-squares fits to the data suggest correlations between both
the FWHM and half-light radius (Reff) of the clusters and their masses (M) at
about the 3-sigma level. Although both relations show a large scatter, the fits
have substantially shallower slopes than for a constant-density relation.
However, many of the youngest clusters have extended halos which make the Reff
determinations uncertain. There is no evidence for galaxy-to-galaxy variations
in the mean cluster sizes. In particular, the mean sizes do not appear to
depend on the host galaxy star formation rate surface density. Many of the
youngest objects (age < 10 Myr) are located in strongly crowded regions, and
about 1/3-1/2 of them are double or multiple sources. The HST images are also
used to check the nature of cluster candidates identified in a previous
ground-based survey. The contamination rate in the ground-based sample is
generally less than about 20%, but some cluster identifications remain
ambiguous because of crowding even with HST imaging, especially for the
youngest objects.


title: Electrostatic Decay of Plasma Turbulence

abstract:
  The study of the evolution of a suprathermal electron beam traveling through
a background plasma is relevant for the physics of solar flares and their
associated type III solar radio bursts. As they evolve guided by the coronal
magnetic field-lines, these beams generate Langmuir turbulence. The
beam-generated turbulence is in turn responsible for the emission of radio
photons at the second harmonic of the local plasma frequency, which are
observed during type III solar radio bursts. To generate the radio emission,
the beam-aligned Langmuir waves must coalesce, and therefore a process capable
of re-directioning the turbulence in an effective fashion is required.
  Different theoretical models identify the electrostatic (ES) decay process L1
-> L2 + S (L: Langmuir wave; S: Ion-acoustic wave) as the re-directioning
mechanism for the L waves. Two different regimes have been proposed to play a
key role: the back-scattering and the diffusive (small angle) scattering. This
paper is a comparative analysis of the decay rate of the ES decay for each
regime, and of the different observable characteristics that are expected for
the resulting ion-acoustic waves.


title: Gamma-Ray Bursts observed by INTEGRAL

abstract:
  During the first six months of operations, six Gamma Ray Bursts (GRBs) have
been detected in the field of view of the INTEGRAL instruments and localized by
the INTEGRAL Burst Alert System (IBAS): a software for the automatic search of
GRBs and the rapid distribution of their coordinates. I describe the current
performances of IBAS and review the main results obtained so far. The
coordinates of the latest burst localized by IBAS, GRB 031203, have been
distributed within 20 s from the burst onset and with an uncertainty radius of
only 2.7 arcmin.


title:
Misleading results from low-resolution spectroscopy: from galaxy
  interstellar medium chemistry to cosmic star formation density

abstract:
  Low resolution spectroscopy (R=150) from the Canada-France-Redshift Survey
(CFRS) had revealed intriguing properties for low redshift galaxies (z<=0.3):
nearly half of their spectra show prominent H\alpha emission line, but no
H\beta emission line and barely detected [O II]3727 and [O III]5007 lines. We
call these objects "CFRS H\alpha-single" galaxies and have re-observed a
subsample of them at higher spectral resolution, associated with a subsample of
more normal emission line galaxies. Good S/N spectroscopy at the VLT and the
CFHT, with moderate spectral resolution (R>600), reveals that the "CFRS
H\alpha-single" galaxies and most of the star forming spirals have high
extinctions (A_V>2), high stellar masses and over-solar oxygen abundances. The
present study shows that it is hard to derive the detailed properties of
galaxies (gas chemical abundances, interstellar extinction, stellar population,
star formation rates and history) using spectra with resolution below 600. One
major drawback is indeed that the underlying Balmer absorption cannot be
estimated properly, which could cause the SFRs be either underestimated or
overestimated by factors reaching 10 (average 3.1) for the sample galaxies.
These effects are prominent for a large fraction of evolved massive galaxies
especially those experiencing successive bursts (A and F stars dominating their
absorption spectra). Further estimates of the cosmic star formation density at
all redshifts mandatorily requires moderate resolution spectroscopy to avoid
severe biases.


title: XMM-Newton view of the prototype narrow-line Seyfert 1 galaxy I Zw 1

abstract:
  We present results based on an XMM-Newton observation of the prototype
narrow-line Seyfert 1 galaxy I Zw 1 performed in June 2002. The 0.6-12 keV
spectrum is well described by a steep power-law (Gamma\sim 2.3) and a weak soft
blackbody component (kT \sim 200 eV) below 2 kev. The soft X-ray excess
emission is featureless and contributes only about 10% to the total X-ray
emission in the $0.6-2\kev$ band. There are tentative evidences for an iron
iron Kalpha line and an iron K edge, both from high ionized He-like iron. The
0.6-12kev continuum of I Zw 1 can be explained in terms of a blackbody (kT \sim
40eV), thermal comptonization and its reflection off the surface of an ionized
accretion disk. We note that characterizing the soft excess copmonent `above a
power law continuum' may not be appropriate due to the low energy curvature of
a comptonized spectrum. X-ray emission from I Zw 1 was highly variabile during
the observation. I Zw 1 showed a large, symmetric X-ray flare during which the
X-ray luminosity increased by about 6e43 erg/s in an interval of 2800s only.
The X-ray spectral variability was unusual during the flare. In contrast to the
general observation of spectral steepening with flux from Seyfert galaxies,
there is a clear evidence for hardening of the 0.6-10kev spectrum of I Zw 1
with increasing flux. This hardening is due to a stronger and slightly flatter
power-law component at higher flux without any change in the soft X-ray excess
component. The large flare, the accompanying spectral flattening, and the
steady nature of the soft excess component may be due to an additional flatter
power-law component during the flare possibly arising as a result of ejection
of electron plasma and the SSC process.


title:
XMM-Newton observations of OY Car III: OM light curve modelling, X-ray
  timing and spectral studies

abstract:
  We revisit the XMM-Newton observations of the dwarf nova OY Car taken in July
2000 which occured shortly after an outburst. Ramsay et al (2001a) found a
prominent energy dependent modulation at a period of 2240 sec: this modulation
was only seen for app. 1/3 of the observation duration. In our new analysis, we
examine this time interval in greater detail. In addition to the 2240 sec
period we find evidence for other periods, the most prominent being near 3500
sec. Both these modulations are most likely due to changes in photoelectric
absorption over this period: this is supported by phase-resolved spectroscopy.
This may indicate the presence of matter above the accretion disc or a presence
of a magnetic accretion curtain. In this case the 2240 sec period could
represent a spin period of the white dwarf and the 3500 sec period a beat
period between the spin and orbital periods. We also model the B band and UV
eclipse profiles and light curves using a new technique to map the spatial
extent of the accretion disc. As a result we find that whilst the optical
emission is dominated by both the emission close to the accretion disc boundary
layer and the hot spot where the accretion stream hits the disc, the UV
emission is mainly dominated by the inner disc/boundary layer only.


title:
The XMM-Newton HBS28 sample: studying the obscuration in hard X-ray
  selected AGNs

abstract:
  This paper presents the analysis of a statistically complete sample of 28
serendipitous X-ray sources selected in 82 pointed XMM-Newton fields down to a
count-rate of 0.002 counts s^-1(4.5-7.5 keV energy band). This is the first
sample selected in this energy range to have complete spectroscopic
identifications and redshift determinations for all the objects. Apart from one
Galactic source (an interacting binary), all the objects are AGNs. Their
optical and X-ray properties (derived from the spectral analysis of the
XMM-EPIC data) are compared together. The good correlation between the optical
spectral type and the X-ray absorption properties supports the AGN unified
model. Only one object that does not fit the relation between optical and X-ray
absorption is found, namely a Seyfert 1.9 with no evidence of obscuration in
the X-ray band (NH<1.3x10^20 cm^-2). In total, 7 sources out of 27 are heavily
obscured in the X-ray (NH>10^22 cm^-2), corresponding to a surface density of
0.7 deg^-2 at the flux limit the sample (4-7x10^-14 erg s^-1 cm^-2 in the
4.5-7.5 keV energy band). Among these obscured objects, two sources show a
large (intrinsic) luminosity (L_[2-10keV]>10^44 erg s^-1) and are thus
classified as type 2 QSO. Finally, we have compared the fraction of X-ray
absorbed AGNs (26%) with that predicted by the current XRB synthesis models at
the flux limit of the survey. We find that the models significantly (~90%
confidence level) over predict the fraction of absorbed AGNs thus confirming
also in this hard energy band (4.5-7.5 keV) similar results recently obtained
in the 2-10 keV band.


title: The MUNICS Project: Galaxy Assembly at 0 < z < 1

abstract:
  We summarize the results obtained from the MUNICS K-band selected Galaxy
survey thus far. MUNICS is a wide-area, medium-deep, photometric and
spectroscopic survey selected in the K band, targeting randomly-selected high
Galactic latitude fields. It covers an area of roughly one square degree in the
K and J bands with optical imaging in the I, R, V, and B bands in 0.5 square
degrees. The MUNICS photometric survey is complemented by spectroscopic
follow-up observations down to limits of K<17.5 (wide area) and K<19.5 (smaller
area). We have obtained 593 redshifts to this date. Here, we present results
concerning the evolution of the K-band luminosity function to z ~ 1, both from
the full photometric redshift sample and from the spectroscopic sample alone.
We also report on new results concerning the evolution of the stellar mass
function to z ~ 1. We fit stellar population synthesis models to our multicolor
photometry to obtain M/L values for each source. We detect significant
evolution in the stellar mass function and we find that more massive systems
evolve faster in number density than less massive systems. We also measure the
evolution of the total stellar mass density of the universe and find that about
half the present day stellar mass formed since z ~ 1.


title: The Supernova Relic Neutrino Backgrounds at KamLAND and Super-Kamiokande

abstract:
  We calculate the Supernova Relic Neutrino (SRN) background flux for the
KamLAND and Super-Kamiokande (SK) detectors, motivated by the reduction in
background at SK and new results for the star formation history (e.g., from the
Sloan Digital Sky Survey (SDSS)). Our best estimate for the flux at SK is
slightly below, but very close to the current SK upper limit. The SK upper
limit is already inconsistent with a range of star formation histories allowed
by the SDSS data. We estimate that the SRN background should be detected (at
1-sigma) at SK with a total of about 9 years (including the existing 4 years)
of data. While KamLAND is a much smaller detector compared to SK, it profits
from being practically background-free and from its sensitivity to the lower
energy supernova neutrinos. KamLAND could make a 1-sigma detection of the SRN
with a total of about 5 years of data. Given the small expected SRN event rate,
we also consider the detection of the SRN in a modified SK detector with a
lower threshold and reduced background where the time to detection can be
reduced by a factor of 10 relative to the existing SK estimate.


title: Gamma Ray Bursts as Electromagnetic Outflows

abstract:
  (Abridged) We interpret gamma ray bursts as relativistic, electromagnetic
explosions. Specifically, we propose that they are created when a rotating,
relativistic, stellar-mass progenitor loses much of its rotational energy in
the form of a Poynting flux during an active period lasting $\sim 100$ s.
Initially, a non-spherically symmetric, electromagnetically-dominated bubble
expands non-relativistically inside the star, most rapidly along the rotational
axis of the progenitor. After the bubble breaks out from the stellar surface
and most of the electron-positron pairs annihilate, the bubble expansion
becomes highly relativistic. After the end of the source activity most of the
electromagnetic energy is concentrated in a thin shell inside the contact
discontinuity between the ejecta and the shocked circumstellar material. This
electromagnetic shell pushes a relativistic blast wave into the circumstellar
medium. Current-driven instabilities develop in this shell at a radius
$\sim3\times10^{16}$ cm and lead to dissipation of magnetic field and
acceleration of pairs which are responsible for the $\gamma$-ray burst. At
larger radii, the energy contained in the electromagnetic shell is mostly
transferred to the preceding blast wave. Particles accelerated at the forward
shock may combine with electromagnetic field from the electromagnetic shell to
produce the afterglow emission.


title: Isolating Geometry in Weak Lensing Measurements

abstract:
  Given a foreground galaxy-density field or shear field, its cross-correlation
with the shear field from a background population of source galaxies scales
with the source redshift in a way that is specific to lensing. Such a
source-scaling can be exploited to effectively measure geometrical distances as
a function of redshift and thereby constrain dark energy properties, free of
any assumptions about the galaxy-mass/mass power spectrum (its shape, amplitude
or growth). Such a geometrical method can yield a ~ 0.03 - 0.07 f_{sky}^{-1/2}
measurement on the dark energy abundance and equation of state, for a
photometric redshift accuracy of dz ~ 0.01 - 0.05 and a survey with median
redshift of ~ 1. While these constraints are weaker than conventional weak
lensing methods, they provide an important consistency check because the
geometrical method carries less theoretical baggage: there is no need to assume
any structure formation model (e.g. CDM). The geometrical method is at the most
conservative end of a whole spectrum of methods which obtain smaller errorbars
by making more restrictive assumptions -- we discuss some examples. Our
geometrical approach differs from previous investigations along similar lines
in three respects. First, the source-scaling we propose to use is less
demanding on the photometric redshift accuracy. Second, the scaling works for
both galaxy-shear and shear-shear correlations. Third, we find that previous
studies underestimate the statistical errors associated with similar
geometrical methods, the origin of which is discussed.


title: An Error Analysis of the Geometric Baade-Wesselink Method

abstract:
  We derive an analytic solution for the minimization problem in the geometric
Baade-Wesselink method. This solution allows deriving the distance and mean
radius of a pulsating star by fitting its velocity curve and angular diameter
measured interferometrically. The method also provide analytic solutions for
the confidence levels of the best fit parameters, and accurate error estimates
for the Baade-Wesselink solution. Special care is taken in the analysis of the
various error sources in the final solution, among which the uncertainties due
to the projection factor, the limb darkening and the velocity curve. We also
discuss the importance of the phase shift between the stellar lightcurve and
the velocity curve as a potential error source in the geometric Baade-Wesselink
method. We finally discuss the case of the Classical Cepheid zeta Gem, applying
our method to the measurements derived with the Palomar Testbed Interferometer.
We show how a careful treatment of the measurement errors can be potentially
used to discriminate between different models of limb darkening using
interferometric techniques.


title: The Formation of the Hubble Sequence

abstract:
  The history of galaxy formation via star formation and stellar mass assembly
rates is now known with some certainty, yet the connection between high
redshift and low redshift galaxy populations is not yet clear. By identifying
and studying individual massive galaxies at high-redshifts, z > 1.5, we can
possibly uncover the physical effects driving galaxy formation. Using the
structures of high-z galaxies, as imaged with the Hubble Space Telescope, we
argue that it is now possible to directly study the progenitors of ellipticals
and disks. We also briefly describe early results that suggest many massive
galaxies are forming at z > 2 through major mergers.


title: Are Cluster Dwarfs Recycled Galaxies?

abstract:
  Although cluster dwarf galaxies are often neglected due to their faintness,
recent observations demonstrate that they are critical for understanding the
physical processes behind galaxy and cluster formation. Dwarfs are the most
common galaxy type and are particularly abundant in clusters. Recent
observational results suggest that dwarfs in dense environments do not all form
early in the universe, as expected from hierarchical structure formation
models. Many of these systems appear to be younger and more metal rich than
dwarfs in lower density areas, suggesting they are possibly created by a tidal
process. Several general galaxy cluster observations, including steep
luminosity functions and the origin of intracluster light, are natural outcomes
of these processes.


title:
The Relationship between Stellar and Halo Masses of Disk Galaxies at z =
  0.2 - 1.2

abstract:
  We present the results of a study to determine the co-evolution of the virial
and stellar masses for a sample of 83 disk galaxies between redshifts z = 0.2 -
1.2. The virial masses of these disks are computed using measured maximum
rotational velocities from Keck spectroscopy and scale lengths from Hubble
Space Telescope imaging. We compute stellar masses based on stellar population
synthesis model fits to spectral energy distributions including K-band
magnitudes. We find no apparent evolution with redshift from z = 0.2 - 1.2 in
the relationship between stellar masses and maximum rotational velocities
through the stellar mass Tully-Fisher relationship. We also find no evolution
when comparing disk stellar and virial masses. Massive disk galaxies therefore
appear to be already in place, in terms of their virial and stellar masses, out
to the highest redshifts where they can be morphologically identified.


title: Setting confidence intervals in coincidence search analysis

abstract:
  The main technique that has been used to estimate the rate of gravitational
wave (gw) bursts is to search for coincidence among times of arrival of
candidate events in different detectors. Coincidences are modeled as a
(possibly non-stationary) random time series background with gw events embedded
in it, at random times but constant average rate. It is critical to test
whether the statistics of the coincidence counts is Poisson, because the counts
in a single detector often are not. At some point a number of parameters are
tuned to increase the chance of detection by reducing the expected background:
source direction, epoch vetoes based on sensitivity, goodness-of-fit
thresholds, etc. Therefore, the significance of the confidence intervals itself
has to be renormalized. This review is an insight of the state-of-the-art
methods employed in the recent search performed by the International
Gravitational Event Collaboration for the worldwide network of resonant bar
detectors.


title:
Keck Spectroscopy and Imaging of Globular Clusters in the Lenticular
  Galaxy NGC 524

abstract:
  We have obtained Keck LRIS imaging and spectra for 29 globular clusters
associated with the lenticular galaxy NGC 524. Using the empirical calibration
of Brodie & Huchra we find that our spectroscopic sample spans a metallicity
range of --2.0 < [Fe/H] < 0. We have compared the composite spectrum of the
metal-poor ([Fe/H] < --1) and metal-rich clusters with stellar population
models and conclude that the clusters are generally old and coeval at the 2
sigma confidence level. To determine the mean [alpha/Fe] ratios of the globular
clusters, we have employed the Milone et al. 'alpha-enhanced' stellar
population models. We verified the reliability of these models by comparing
them with high S/N Galactic globular cluster data. We observe a weak trend of
decreasing [alpha/Fe] with increasing metallicity in the NGC 524 clusters.
Analysis of the cluster system kinematics reveals that the full sample exhibits
a rotation of 114+/-60 km/s around a position angle of 22+/-27 deg, and a
velocity dispersion of 186+/-29 km/s at a mean radius of 89 arcsec from the
galaxy centre. Subdividing the clusters into metal-poor and metal-rich
subcomponents we find that the metal-poor (17) clusters and metal-rich (11)
clusters have similar velocity dispersions (197+/-40 km/s and 169+/-47 km/s
respectively). The metal-poor clusters dominate the rotation in our sample with
147+/-75 km/s, whilst the metal-rich clusters show no significant rotation
(68+/-84 km/s). We derive a virial and projected mass estimation for NGC 524 of
between 4 and 13 x 10^11 Msun (depending on the assumed orbital distribution)
interior to 2 effective radii of this galaxy.


title:
X-ray afterglows of gamma-ray bursts in the synchrotron self-Compton
  dominated regime

abstract:
  We consider in this paper the effect of synchrotron self-Compton process on
X-ray afterglows of gamma-ray bursts. We find that for a wide range of
parameter values, especially for the standard values which imply the energy in
the electrons behind the afterglow shock is tens times as that in the magnetic
field, the electron cooling is dominated by Compton cooling rather than
synchrotron one. This leads to a different evolution of cooling frequency in
the synchrotron emission component, and hence a different (flatter) light curve
slope in the X-ray range. This effect should be taken into account when
estimating the afterglow parameters by X-ray observational data. For somewhat
higher ambient density, the synchrotron self-Compton emission may be directly
detected in X-ray range, showing varying spectral slopes and a quite steep
light curve slope.


title: A Discovery of a Peculiar Pulsar in the Small Magellanic Cloud

abstract:
  We report on a peculiar X-ray binary pulsar IKT1 = RXJ0047.3-7312 observed
with XMM-Newton in Oct. 2000. The X-ray spectrum is described by a
two-component spectrum. The hard component has a broken power-law with
respective photon indices of 0.2 and 1.8, below and above the break energy at
5.8 keV. The soft component can be modeled by a blackbody of kT = 0.6 keV. The
X-ray flux shows a gradual decrease and periodic variations of about 4000 s.
The averaged flux in 0.7-10.0 keV is 2.9x10^-12 ergs/cm^2/s, which is ~10 times
brighter than that in a ROSAT observation in Nov. 1999. In addition to the
4000-s variation, we found coherent pulsations of 263 +/- 1 s. These
discoveries strengthen the Be/X-ray binary scenario proposed by the ROSAT and
ASCA observations on this source, and confirm that most of the hard sources in
the Small Magellanic Cloud are X-ray binary pulsars. A peculiar property of
this XBP is that the coherent pulsations are found only in the soft component,
and the folded light curve shows a flat top shape with a sharp dip. We discuss
the nature of this XBP focusing on the peculiar soft component.


title: Low Mass Stars and Substellar Objects in the NGC 1333 Molecular Cloud

abstract:
  We present the results of near-infrared imaging and low-resolution near-
infrared spectroscopy of low mass objects in the NGC 1333 molecular cloud. A
JHK survey of an 11.4' x 11.7' area of the northern cluster was conducted to a
sensitivity of K < 16 mag. Using near-infrared magnitudes and colors from this
and previously published surveys, twenty-five brown dwarf candidates were
selected toward the high extinction cloud core. Spectra in the K band were
obtained and comparisons of the depths of water vapor absorption bands in our
candidate objects with a grid of dwarf,subgiant, and giant standards were made
to derive spectral types. These data were then used to derive effective
temperatures and stellar luminosities which, when combined with theoretical
tracks and isochrones for pre-main sequence objects, resulted in estimates for
their masses and ages. The models suggest a median age for the sample of < 1
Myr with substellar masses for at least 9 of the candidates including the x-ray
flare source ASR 24. Surface gravities have been estimated for the brown dwarf
candidates and, for a given spectral type,found to resemble more closely dwarfs
than giants. Using the near-infrared imaging data and age estimates from the
spectroscopic sample, an extinction-limited sample in the northern cluster was
defined. Consistent with recent studies of other young clusters, this sample
exhibits an accretion disk frequency of 0.75 +-0.20 and a mass spectrum slope
across the hydrogen-burning limit of alpha < 1.6 where dN/dM ~ M^-(alpha).


title: Sunyaev-Zel'dovich power spectrum with decaying cold dark matter

abstract:
  Recent studies of structures of galaxies and clusters imply that dark matter
might be unstable and decay with lifetime $\Gamma^{-1}$ about the age of
universe. We study the effects of the decay of cold dark matter on the
Sunyaev-Zel'dovich (SZ) power spectrum. We analytically calculate the SZ power
spectrum taking finite lifetime of cold dark matter into account. We find the
finite lifetime of dark matter decreases the power at large scale ($l < 4000$)
and increases at small scale ($l > 4000$). This is in marked contrast with the
dependence of other cosmological parameters such as the amplitude of mass
fluctuations $\sigma_{8}$ and the cosmological constant $\Omega_{\lambda}$
(under the assumption of a flat universe) which mainly change the normalization
of the angular power spectrum. This difference allows one to determine the
lifetime and other cosmological parameters rather separately. We also
investigate sensitivity of a future SZ survey to the cosmological parameters
including the life time, assuming a fiducial model $\Gamma^{-1} = 10 h^{-1}
{\rm Gyr}$, $\sigma_{8} = 1.0$, and $\Omega_{\lambda} = 0.7$. We show that
future SZ surveys such as ACT, AMIBA, and BOLOCAM can determine the lifetime
within factor of two even if $\sigma_{8}$ and $\Omega_{\lambda}$ are
marginalized.


title: Earliest spectroscopy of the GRB030329 optical transient

abstract:
  We present the earliest BTA (SAO RAS 6-m telescope) spectroscopic
observations of the GRB030329 optical transient (OT), which almost coincide in
time with the first "break" (t ~ 0.5 day after the GRB) of the OT light curve.
The BTA/MPFS (Multi Pupil Fiber Spectrograph) spectra are clearly not smooth:
the OT spectra showed a continuum with several broad spectral features at about
4000, 4450, 5900AA. The OT spectrum showed some evolution starting from the
first night after the burst, and the beginning of spectral changes are seen as
early as ~10-12 hours after the GRB. The onset of the spectral changes for t <
1 day indicates that the contribution from Type Ic supernova (SN) into the OT
optical flux can be detected earlier. So, summarizing our and other
spectroscopic data on the OT we confirm the evolution of the OT spectrum and
color pointed also by other authors (Hjorth et al. 2003; Matheson et al.
2003b). The early spectra of GRB030329/SN2003dh properties can be consistent
with a shock moving into a stellar wind formed from the pre-SN. Such a behavior
(similar to one near the UV shock breakout in SNe) can be explained by the
existence of a dense matter in the immediate surroundings of GRB/SN progenitor.


title:
Can a "standard" Initial Mass Function explain the metal enrichment in
  clusters of galaxies?

abstract:
  It is frequently debated in literature whether a "standard" Initial Mass
Function (IMF) - meaning an IMF of the kind usually adopted to explain the
chemical evolution in the local Solar Neighbourhood - can account for the
observed metal enrichment and Iron Mass-to-Light Ratio in clusters of galaxies.
We address this problem by means of straightforward estimates that should hold
independently of the details of chemical evolution models.
  It is crucial to compute self-consistently the amount of mass and metals
locked-up in stars, by accounting for the stellar mass-to-light ratio predicted
by a given IMF. It becomes then clear that a "standard" Solar Neighbourhood IMF
cannot provide enough metals to account for the observed chemical properties in
clusters: clusters of galaxies and the local environment must be characterized
by different IMFs.
  Alternatively, if we require the IMF to be universal, in order to explain
clusters such an IMF must be much more efficient in metal production than
usually estimated for the Solar Vicinity. In this case, substantial loss of
metals is required from the Solar Neighbourhood and from disc galaxies in
general. This "non-standard" scenario for the local chemical evolution would
challenge our present understanding of the Milky Way and of disc galaxy
formation.


title:
The nuclear reaction waiting points, Mg22, Si26, S30, and Ar34, and
  bolometrically double peaked type I X-ray bursts

abstract:
  Type I X-ray bursts with a double peak in the bolometric luminosity have been
observed from several sources. The separation between the two peaks are on the
order of a few seconds. We propose a nuclear waiting point impedance in the
thermonuclear reaction flow to explain these observations. Nuclear structure
information suggests the potential waiting points: Mg22, Si26, S30 and Ar34,
which arise in conditions, where a further reaction flow has to await a
beta-decay, because the (alpha,p)-reaction is too weak to overcome the target
Coulomb-barrier and the (p,gamma)-reaction is quenched by photo-disintegration
at the burst temperature. The conclusion is that the effects of the
experimentally unknown S30(alpha,p)Cl33 and Ar34(alpha,p)K37 might be directly
visible in the observation of X-ray burst light curves.


title:
The Mouse That Soared: High Resolution X-ray Imaging of the
  Pulsar-Powered Bow Shock G359.23-0.82

abstract:
  We present an observation with the Chandra X-ray Observatory of the unusual
radio source G359.23-0.82 ("the Mouse"), along with updated radio timing data
from the Parkes radio telescope on the coincident young pulsar J1747-2958. We
find that G359.23-0.82 is a very luminous X-ray source (L_X [0.5-8.0 keV] =
5e34 ergs/s for a distance of 5 kpc), whose morphology consists of a bright
head coincident with PSR J1747-2958, plus a 45"-long narrow tail whose
power-law spectrum steepens with distance from the pulsar. We thus confirm that
G359.23-0.82 is a bow-shock pulsar wind nebula powered by PSR J1747-2958; the
nebular stand-off distance implies that the pulsar is moving with a Mach number
of ~60, suggesting a space velocity ~600 km/s through gas of density ~0.3
cm^-3. We combine the theory of ion-dominated pulsar winds with hydrodynamic
simulations of pulsar bow shocks to show that a bright elongated X-ray and
radio feature extending 10'' behind the pulsar represents the surface of the
wind termination shock. The X-ray and radio "trails" seen in other pulsar bow
shocks may similarly represent the surface of the termination shock, rather
than particles in the postshock flow as is usually argued. The tail of the
Mouse contains two components: a relatively broad region seen only at radio
wavelengths, and a narrow region seen in both radio and X-rays. We propose that
the former represents material flowing from the wind shock ahead of the
pulsar's motion, while the latter corresponds to more weakly magnetized
material streaming from the backward termination shock. This study represents
the first consistent attempt to apply our understanding of "Crab-like" nebulae
to the growing group of bow shocks around high-velocity pulsars.


title:
The expected abundance of Lyman-$\alpha$ emitting primeval galaxies. I.
  General model predictions

abstract:
  We present model calculations for the expected surface density of Ly-$\alpha$
emitting primeval galaxies (PGs) at high redshifts. We assume that elliptical
galaxies and bulges of spiral galaxies (= spheroids) formed early in the
universe and that the Ly-$\alpha$ emitting PGs are these spheroids during their
first burst of star formation at high redshift. One of the main assumptions of
the models is that the Ly-$\alpha$ bright phase of this first starburst in the
spheroids is confined to a short period after its onset due to rapid formation
of dust. The models do not only explain the failure of early surveys for
Ly-$\alpha $ emitting PGs but are also consistent with the limits of new
surveys (e.g. the Calar Alto Deep Imaging Survey - CADIS). At faint detection
limits $S_{lim} \le 10^{-20}$W/m$^2$ the surface density of Ly-$\alpha$
emitters is expected to vary only weakly in the redshift range between $z=3$
and $z=6$ with values $> 10^3 / {deg}^2 / \Delta z = 0.1 $ reaching its maximum
at $z_0 \approx 4$. At shallower detection limits, $S_{lim} \ge 3\times
10^{-20}$W/m$^2$ the surface density of high-z Ly-$\alpha$ emitters is expected
to be a steep function of redshift and detection limit. This explains the low
success in finding bright Ly-$\alpha$ galaxies at $z > 5$. We demonstrate how
the observed surface densities of Ly-$\alpha $ emitting PGs derived from recent
surveys constrain the parameters of our models. Finally, we discuss the
possibility that two Ly-$\alpha$ bright phases occur in the formation process
of galaxies: An initial -- primeval -- phase in which dust is virtually
non-existing, and a secondary later phase in which strong galactic winds as
observed in some Lyman break galaxies facilitate the escape of Ly-$\alpha $
photons after dust has already been formed.


title: Dust and Super Star Clusters in NGC 5253

abstract:
  We present new observations of the famous starburst galaxy NGC 5253 which
owes its celebrity to possibly being the youngest and closest starburst galaxy
known. Our observations in the infrared and millimeter contribute to shed light
on the properties of this interesting object. We have used our new data along
with data from the literature to study the properties of the young stellar
clusters present in NGC 5253. We find that the brightest optical clusters are
all characterized by a near-infrared excess that is explained by the combined
effect of extinction and emission by dust. For the brightest infrared cluster
we model the spectral energy distribution from the optical to the radio. We
find that this cluster dominates the galaxy emission longward of 3 \mic, that
it has a bolometric luminosity of $1.2~10^9 L_{\odot}$ and a mass of $1.2~10^6
M_{\odot}$, giving $L/M\approx10^3$. The cluster is obscured by 7 mag of
optical extinction produced by about 1.5 10$^{5}$ $M_{\odot}$ of dust. The dust
properties are peculiar with respect to the dust properties in the solar
neighbourhood with a composition characterized by a lack of silicates and a
flatter size distribution than the standard one, i.e. a bias toward larger
grains. We find that NGC 5253 is a striking example of a galaxy where the
infrared-submillimeter and ultraviolet-optical emissions originate in totally
decoupled regions of vastly different physical sizes.


title: Tracing the Magnetic Field in Orion A

abstract:
  We use extensive 350 um polarimetry and continuum maps obtained with Hertz
and SHARC II along with HCN and HCO+ spectroscopic data to trace the
orientation of the magnetic field in the Orion A star-forming region. Using the
polarimetry data, we find that the direction of the projection of the magnetic
field in the plane of the sky relative to the orientation of the
integral-shaped filament varies considerably as one moves from north to south.
While in IRAS 05327-0457 and OMC-3 MMS 1-6 the projection of the field is
primarily perpendicular to the filament it becomes better aligned with it at
OMC-3 MMS 8-9 and well aligned with it at OMC-2 FIR 6. The OMC-2 FIR 4 cloud,
located between the last two, is a peculiar object where we find almost no
polarization. The projected angle of the field is more complicated in OMC-1
where it exhibits smooth variations in its orientation across the face of this
massive complex. By combining the polarimetry and spectroscopic data we were
able to measure a set of average values for the inclination angle of the
magnetic field relative to the line of sight. We find that the field is
oriented quite close to the plane of the sky in most places. More precisely,
the inclination of the magnetic field is ~73 deg. around OMC-3 MMS 6, ~74 deg.
at OMC-3 MMS 8-9, ~80 deg. at OMC-2 FIR 4, ~65 deg. in the northeastern part of
OMC-1, and ~49 deg. in the Bar. We also present polarimetry data for the OMC-4
region located some 13 arcminutes south of OMC-1.


title:
Bubbles in Planetary Nebulae and Clusters of Galaxies: Instabilities at
  Bubble Fronts

abstract:
  I study the stability of off-center low-density more or less spherical (fat)
bubbles in clusters of galaxies and in planetary nebulae (PNs) to
Rayleigh-Taylor (RT) instability. As the bubble expands and decelerates, the
interface between the low-density bubble's interior and the dense shell formed
from the accreted ambient medium is RT-stable. If, however, in a specific
direction the density decreases such that this segment is accelerated by the
pressure inside the bubble, then this accelerated region is RT-unstable. The
outermost region, relative to the center of the system, is the most likely to
become unstable because there the density gradient is the steepest. Using
simple analytical analysis, I find that off-center fat bubbles in PNs are much
less stable than in clusters. In PNs bubbles become unstable when they are very
small relative to their distance from the center; they can be stabilized
somewhat if the mass loss rate from the stellar progenitor decreases for a
time, such that the negative density gradient is much shallower. In clusters
fat bubbles become unstable when their size is comparable to their distance
from the center. I discuss some implications of this instability in clusters
and in PNs.


title: CII, CI, and CO in the massive star forming region W3 Main

abstract:
  We have used the KOSMA 3m telescope to map the core 7'x5' of the Galactic
massive star forming region W3Main in the two fine structure lines of atomic
carbon and four mid-J transitions of CO and 13CO. In combination with a map of
singly ionized carbon (Howe et al. 1991), and FIR fine structure line data
observed by ISO/LWS at the center position, these data sets allow to study in
detail the physical structure of the photon dominated cloud interface regions
(PDRs) where the occurance of carbon changes from CII to CI, and to CO.


title:
Diffusion in stellar interiors: critical tests of three numerical
  methods

abstract:
  We describe and discuss the properties of three numerical methods for solving
the diffusion equation for the transport of the chemical species and of the
angular momentum in stellar interiors. We study through numerical experiments
both their accuracy and their ability to provide physical solutions. On the
basis of new tests and analyses applied to the stellar astrophysical context,
we show that the most robust method to follow the secular evolution is the
implicit finite differences method. The importance of correctly estimating the
diffusion coefficient between mesh points is emphasized and a procedure for
estimating the average diffusion coefficient between a convective and a
radiative zone is described.


title: Isolated neutron stars: An astrophysical perspective

abstract:
  We briefly review selected results in astrophysics of neutron stars (NSs)
obtained during the last two years, focusing on isolated radioquiet objects. We
discuss in some details population synthesis of close-by isolated NSs, spectra
of INSs, detection of spectral features in these sources (including cyclotron
features), recent results on velocity distribution of NSs and accretion onto
INSs.


title:
Detailed Studies of Cloud Cores: Probing the Initial Conditions for
  Protostellar Collapse

abstract:
  Improving our understanding of the earliest stages of star formation is
crucial to gain insight into the origin of stellar masses, multiple systems,
and protoplanetary disks. We discuss recent advances made in this area thanks
to detailed mapping observations at infrared and (sub)millimeter wavelengths.
Although ambipolar diffusion appears to be too slow to play a direct role in
the formation of dense cores, there is nevertheless good evidence that the
gravitational collapse of isolated protostellar cores is strongly magnetically
controlled. We also argue that the beginning of protostellar collapse is much
more violent in cluster-forming clouds than in regions of distributed star
formation.


title:
Observation and implications of the Epeak - Eiso correlation in
  Gamma-Ray Bursts

abstract:
  The availability of a few dozen GRB redshifts now allows studies of the
intrinsic properties of these high energy transients. Amati et al. recently
discovered a correlation between Epeak, the intrinsic peak energy of the $\nu f
\nu$ spectrum, and Eiso, the isotropic equivalent energy radiated by the
source. Lamb et al. have shown that HETE-2 data confirm and extend this
correlation. We discuss here one of the consequences of this correlation: the
existence of a 'spectral standard candle', which can be used to construct a
simple redshift indicator for GRBs.


abstract:
  Chemical compositions of four barium stars HD 26886, HD 27271, HD 50082 and
HD 98839 are studied based on high resolution, high signal-to-noise Echelle
spectra. Results show that all of them are disk stars. Their \alpha and iron
peak elements are similar to the solar abundances. The neutron-capture process
elements are overabundant relative to the Solar. The heavy-element abundances
of the strong Ba star HD 50082 are higher than those of other three mild Ba
stars. Its mass is 1.32Msun (+0.28,-0.22Msun), and is consistent with the
average mass of strong Ba stars (1.5Msun). For mild Ba star HD 27271 and HD
26886, the derived masses are 1.90Msun (+0.25,-0.20Msun) and 2.78Msun
(+0.75,-0.78M_sun), respectively, which are consistent with the average mass of
mild Ba stars. We also calculate the theoretical abundances of Ba stars by
combining the AGB stars nucleosynthesis and wind accretion formation scenario
of Ba binary systems. The comparisons between the observed abundance patterns
of the sample stars with the theoretical results show that wind accretion
scenario can explain the abundance patterns of HD 50082 and HD 27271 well, but
fail to explain the abundances of HD 26886. It means that the mild Ba star HD
26886, with shorter orbital period (P<1600 d), may be formed from other
scenarios. The high mass mild Ba star HD 98839, with 3.62M_sun, and with very
long orbital period (P>11000 d), may be either a star with the heavy elements
enriched by itself or a "true Ba" star.


title: The rotational broadening and the mass of the donor star of GRS 1915+105

abstract:
  The binary parameters of the microquasar GRS 1915+105 have been determined by
the detection of Doppler-shifted 12CO and 13CO lines in its K-band spectrum
(Greiner et al., 2001, Nature, 414, 522). Here, we present further analysis of
the same K-band VLT spectra and we derive a rotational broadening of the donor
star of V sin i=26+-3 km/s from the 12CO/13CO lines. Assuming that the K-type
star is tidally locked to the black hole and is filling its Roche-lobe surface,
then the implied mass ratio is q = M_d/M_x = 0.058+-0.033. This result,
combined with (P, K, i)=(33.5 d, 140 km/s, 66 deg) gives a more refined mass
estimate for the black hole, $M_x=14.0+-4.4 M_{\odot}$, than previously
estimated, using an inclination of i=66+-2 deg (Fender et al. 1999) as derived
from the orientation of the radio jets and a more accurate distance. The mass
for the early K-type giant star is $M_d=0.81\pm0.53 M_{\odot}$, consistent with
a more evolved stripped-giant donor star in GRS 1915+105 than, for example, the
donor star of the prototype black-hole X-ray transient, V404 Cyg which has the
longest binary period after GRS 1915+105.


title: Ultra-High Energy Cosmic Rays from Quasar Remnants

abstract:
  One of the models recently proposed to explain the origin of the ultra high
energy cosmic rays assumes that these particles may be accelerated by the
electromotive force around presently inactive quasar remnants. We study
predictions for large and small scale ultra high energy cosmic ray arrival
direction anisotropies in a scenario where the particles are injected with a
mono-energetic spectrum by a discrete distribution of such sources. We find
that known quasar remnants are typically distributed too anisotropically to
explain the isotropic ultra high energy cosmic ray flux except in the
unrealistic case where extragalactic magnetic fields of ~0.1 microGauss extend
over many Mpc.


title: Large scale cosmic-ray anisotropy with KASCADE

abstract:
  The results of an analysis of the large scale anisotropy of cosmic rays in
the PeV range are presented. The Rayleigh formalism is applied to the right
ascension distribution of extensive air showers measured by the KASCADE
experiment.The data set contains about 10^8 extensive air showers in the energy
range from 0.7 to 6 PeV. No hints for anisotropy are visible in the right
ascension distributions in this energy range. This accounts for all showers as
well as for subsets containing showers induced by predominantly light
respectively heavy primary particles. Upper flux limits for Rayleigh amplitudes
are determined to be between 10^-3 at 0.7 PeV and 10^-2 at 6 PeV primary
energy.


title:
Local models of stellar convection: Reynolds stresses and turbulent heat
  transport

abstract:
  We study stellar convection using a local three-dimensional MHD model, with
which we investigate the influence of rotation and large-scale magnetic fields
on the turbulent momentum and heat transport. The former is studied by
computing the Reynolds stresses, the latter by calculating the correlation of
velocity and temperature fluctuations, both as functions of rotation and
latitude. We find that the horisontal correlation, Q_(theta phi), capable of
generating horisontal differential rotation, is mostly negative in the southern
hemisphere for Coriolis numbers exceeding unity, corresponding to equatorward
flux of angular momentum in accordance with solar observations. The radial
component Q_(r phi) is negative for slow and intermediate rotation indicating
inward transport of angular momentum, while for rapid rotation, the transport
occurs outwards. Parametrisation in terms of the mean-field Lambda-effect shows
qualitative agreement with the turbulence model of Kichatinov & R\"udiger
(1993) for the horisontal part H \propto Q_(theta phi)/cos(theta), whereas for
the vertical part, V \propto Q_(r phi)/sin(theta), agreement only for
intermediate rotation exists. The Lambda-coefficients become suppressed in the
limit of rapid rotation, this rotational quenching being stronger for the V
component than for H. We find that the stresses are enhanced by the presence of
the magnetic field for field strengths up to and above the equipartition value,
without significant quenching. Concerning the turbulent heat transport, our
calculations show that the transport in the radial direction is most efficient
at the equatorial regions, obtains a minimum at midlatitudes, and shows a
slight increase towards the poles. The latitudinal heat transport does not show
a systematic trend as function of latitude or rotation.


title:
X-ray spectral evolution of SAX J1747.0-2853 during outburst activity
  and confirmation of its transient nature

abstract:
  SAX J1747.0-2853 is an X-ray transient which exhibited X-ray outbursts yearly
between 1998 and 2001, and most probably also in 1976. The outburst of 2000 was
the longest and brightest. We have analyzed X-ray data sets that focus on the
2000 outburst and were obtained with BeppoSAX, XMM-Newton and RXTE. The data
cover unabsorbed 2--10 keV fluxes between 0.1 and 5.3 X 10^-9 erg/s/cm^2. The
equivalent luminosity range is 6 X 10^35 to 2 X 10^37 erg/s. The 0.3--10 keV
spectrum is well described by a combination of a multi-temperature disk
blackbody, a hot Comptonization component and a narrow Fe-K emission line at
6.5 to 6.8 keV with an equivalent width of up to 285 eV. The hydrogen column
density in the line of sight is (8.8+/-0.5) X 10^22 cm^-2. The most conspicuous
spectral changes in this model are represented by variations of the temperature
and radius of the inner edge of the accretion disk, and a jump of the
equivalent width of the Fe-K line in one observation. Furthermore, 45 type-I
X-ray bursts were unambiguously detected between 1998 and 2001 which all
occurred during or close to outbursts. We derive a distance of 7.5+/-1.3 kpc
which is consistent with previous determinations. Our failure to detect bursts
for prolonged periods outside outbursts provides indirect evidence that the
source returns to quiescence between outbursts and is a true transient.


title: Stellar Flares and Coronal Structure

abstract:
  Coronal structure and coronal heating are intimately related in magnetically
active stars. Coronal structure is commonly inferred from radio interferometry
and from eclipse and rotational modulation studies. We discuss to what extent
flares may be responsible for coronal structure and global observable
properties in magnetically active stars.


title: Twisted accretion curtains in the intermediate polar FO Aquarii

abstract:
  We report on a ~37-ks XMM-Newton observation of the intermediate polar FO
Aquarii, presenting X-ray and UV data from the EPIC and OM cameras. We find
that the system has changed from its previously reported state of disc-overflow
accretion to one of purely disc-fed accretion. We detect the previously
reported `notch' feature in the X-ray spin pulse, and explain it as a partial
occultation of the upper accretion pole. Maximum flux of the quasi-sinusoidal
UV pulse coincides with the notch, in keeping with this idea. However, an
absorption dip owing to the outer accretion curtains occurs 0.27 later than the
expected phase, which implies that the accretion curtains are twisted, trailing
the magnetic poles. This result is the opposite of that reported in PQ Gem,
where accreting field lines were found to lead the pole. We discuss how such
twists relate to the accretion torques and thus the observed period changes of
the white dwarfs, but find no simple connection.


title: On the magnetic accretor GK Persei in outburst

abstract:
  RXTE made 5 X-ray observations of the magnetic accretor GK Per during its
1996 outburst, recording a count rate of ten times the quiescent level. The
351-s spin pulse shows a deep, nearly sinusoidal modulation, in contrast to the
weaker, double-humped profile of quiescence. The spectrum shows absorption
increased by two orders of magnitude over quiescence. We explain these
differences in terms of the changing accretion geometry as the outbursting disc
forces the magnetosphere inwards, and discuss the 5000-s X-ray QPOs seen during
GK Per's outbursts.


title:
Simultaneous multi-wavelength observations of microquasars (the MINE
  collaboration)

abstract:
  We present the international collaboration MINE (Multi-lambda INTEGRAL
NEtwork) aimed at conducting multi-wavelength observations of microquasars
simultaneously with the INTEGRAL satellite. The first results on GRS 1915+105
are encouraging and those to come should help us to understand the physics of
the accretion and ejection phenomena around a compact object.


title: "Osiris"(HD209458b), an evaporating planet

abstract:
  Three transits of the planet orbiting the solar type star HD209458 were
observed in the far UV at the wavelength of the HI Ly-alpha line. The planet
size at this wavelength is equal to 4.3 R_Jup, i.e. larger than the planet
Roche radius (3.6 R_Jup). Absorbing hydrogen atoms were found to be blueshifted
by up to -130 km/s, exceeding the planet escape velocity. This implies that
hydrogen atoms are escaping this ``hot Jupiter'' planet. An escape flux of >~
10^10g/s is needed to explain the observations. Taking into account the tidal
forces and the temperature rise expected in the upper atmosphere, theoretical
evaluations are in good agreement with the observed rate. Lifetime of planets
closer to their star could be shorter than stellar lifetimes suggesting that
this evaporating phenomenon may explain the lack of planets with very short
orbital distance.
  This evaporating planet could be represented by the Egyptian God ``Osiris''
cut into pieces and having lost one of them. This would give us a much easier
way to name that planet and replace the unpleasant ``HD209458b'' name used so
far.


title: The data analysis of HD209458 Ly-alpha transit occultation

abstract:
  Using STIS - HST observations, we have detected an extended upper atmosphere
in the extrasolar planet HD209458b . The spectra show an absorption of
(15+/-4)% of the stellar Ly-alpha emission line during the planetary transit in
front of the star. This is interpreted as the signature of HI evaporation
taking place around the planet within an extended upper atmosphere
(Vidal-Madjar et al. 2003). We present the data analysis of these observations.
A particular attention is paid to the background correction and the airglow
subtraction.


title: Evaporation rate of hot Jupiters and formation of Chthonian planets

abstract:
  Among the hundred of known extrasolar planets, about 15% are closer than 0.1
AU from their parent stars. But there are extremely few detections of planets
orbiting in less than 3 days. At this limit the planet HD209458b has been found
to have an extended upper atmosphere of escaping hydrogen. This suggests that
the so-called hot Jupiters which are close to their parent stars could
evaporate.
  Here we estimate the evaporation rate of hydrogen from extrasolar planets in
the star vicinity. With high exospheric temperatures, and owing to the tidal
forces, planets evaporate through a geometrical blow-off. This may explain the
absence of Jupiter mass planets below a critical distance from the stars. Below
this critical distance, we infer the existence of a new class of planets made
of the residual central core of former hot Jupiters, which we propose to call
the ``Chthonian'' planets.


title:
The Ionized Gas in Local Starburst Galaxies: Global and Small--Scale
  Feedback from Star Formation

abstract:
  Abridged: The small-- and intermediate--scale structure and the fraction of
the ISM ionized by non--radiative processes is investigated in a small sample
of four local starburst galaxies, imaged with the HST WFPC2. The sample
comprises three dwarf galaxies, NGC3077, NGC4214, and NGC5253, and one giant
spiral, NGC5236 (M83). The galaxies span a range in metallicity, luminosity,
and environment, enabling the investigation of non--radiative ionization
processes in a variety of galactic conditions. For this purpose, the four
galaxies were imaged in the lines of H-beta(4861 A), [OIII](5007 A),
H-alpha(6563 A), and [SII](6717,6731 A). The non--photoionized gas in these
galaxies has been traced on scales ranging from a few tens of pc to a few
hundred pc, providing a full budget for this ionized gas component. Using the
`maximum starburst line' of Kewley et al. (2001) to discriminate between
photoionized and non--photoionized gas, we find that in all four galaxies
non--photoionization processes are responsible for a small fraction of the
total H-alpha emission, at the level of 3%--4%. The starbursts in the three
dwarf galaxies deposit a significant fraction, 70%-100%, of their mechanical
energy into the surrounding interstellar medium and require time--extended (a
few x 10^7 yr to ~10^8 yr) star formation, in order to account for the observed
luminosity of the non--photoionized gas. In the massive spiral, the
non--photoionized gas is concentrated in localized areas surrounded by active
star--formation, with no evidence for extended structures (as those in the
dwarfs). This confirms the picture that starbursts remain confined events in
massive galaxies, likely due to the deep potential well.


title: Effects of Helium Phase Separation on the Evolution of Giant Planets

abstract:
  We present the first models of Saturn and Jupiter to couple their evolution
to both a radiative-atmosphere grid and to high-pressure phase diagrams of
hydrogen with helium. The purpose of these models is to quantify the
evolutionary effects of helium phase separation in Saturn's deep interior. We
find that prior calculated phase diagrams in which Saturn's interior reaches a
region of predicted helium immiscibility do not allow enough energy release to
prolong Saturn's cooling to its known age and effective temperature. We explore
modifications to published phase diagrams that would lead to greater energy
release, and find a modified H-He phase diagram that is physically reasonable,
leads to the correct extension of Saturn's cooling, and predicts an atmospheric
helium mass fraction Y_atmos in agreement with recent estimates. We then expand
our inhomogeneous evolutionary models to show that hypothetical extrasolar
giant planets in the 0.15 to 3.0 Jupiter mass range may have T_effs 10-15 K
greater than one would predict with models that do not incorporate helium phase
separation.


title:
On Collisionless Electron-Ion Temperature Equilibration in the Fast
  Solar Wind

abstract:
  We explore a mechanism, entirely new to the fast solar wind, of electron
heating by lower hybrid waves to explain the shift to higher charge states
observed in various elements in the fast wind at 1 A.U. relative to the
original coronal hole plasma. This process is a variation on that previously
discussed for two temperature accretion flows by Begelman & Chiueh. Lower
hybrid waves are generated by gyrating minor ions (mainly alpha-particles) and
become significant once strong ion cyclotron heating sets in beyond 1.5 R_sun.
In this way the model avoids conflict with SUMER electron temperature
diagnostic measurements between 1 and 1.5 R_sun. The principal requirement for
such a process to work is the existence of density gradients in the fast solar
wind, with scale length of similar order to the proton inertial length. Similar
size structures have previously been inferred by other authors from radio
scintillation observations and considerations of ion cyclotron wave generation
by global resonant MHD waves.


title: The Effect of Bound Dineutrons upon BBN

abstract:
  We have examined the effects of a bound dineutron, n2, upon big bang
nucleosynthesis (BBN) as a function of its binding energy B_n2. We find a
weakly bound dineutron has little impact but as B_n2 increases its presence
begins to alter the flow of free nucleons to helium-4. Due to this disruption,
and in the absence of changes to other binding energies or fundamental
constants, BBN sets a reliable upper limit of B_n2 <~ 2.5 MeV in order to
maintain the agreement with the observations of the primordial helium-4 mass
fraction and D/H abundance.


title: Non-Adiabatic Perturbations from Single-Field Inflation

abstract:
  If the inflaton decays into several components during reheating, and if the
corresponding decay rates are functions of spacetime-dependent quantities, it
is possible to generate entropy perturbations after a stage of single-field
inflation. In this paper, I present a simple toy example that illustrates this
possibility. In the example, the decay rates of the inflaton into ``matter''
and ``radiation'' are different functions of the total energy density. In
particular cases, one can exactly solve the equations of motion both for
background and perturbations in the long-wavelength limit, and show that
entropy perturbations do indeed arise. Beyond these specific examples, I
attempt to identify what are the essential ingredients responsible for the
generation of entropy perturbations after single-field inflation, and to what
extent these elements are expected to be present in realistic models.