title:
Dielectronic recombination data for dynamic finite-density plasmas I.
  Goals and methodology

abstract:
  A programme is outlined for the assembly of a comprehensive dielectronic
recombination database within the generalized collisional--radiative (GCR)
framework. It is valid for modelling ions of elements in dynamic finite-density
plasmas such as occur in transient astrophysical plasmas such as solar flares
and in the divertors and high transport regions of magnetic fusion devices. The
resolution and precision of the data are tuned to spectral analysis and so are
sufficient for prediction of the dielectronic recombination contributions to
individual spectral line emissivities. The fundamental data are structured
according to the format prescriptions of the Atomic Data and Analysis Structure
(ADAS) and the production of relevant GCR derived data for application is
described and implemented following ADAS. The requirements on the dielectronic
recombination database are reviewed and the new data are placed in context and
evaluated with respect to older and more approximate treatments. Illustrative
results validate the new high-resolution zero-density dielectronic
recombination data in comparison with measurements made in heavy-ion storage
rings utilizing an electron cooler. We also exemplify the role of the
dielectronic data on GCR coefficient behaviour for some representative light
and medium weight elements.


title:
The Relation between Black Hole Mass, Bulge Mass, and Near-Infrared
  Luminosity

abstract:
  We present new accurate near-infrared (NIR) spheroid (bulge) structural
parameters obtained by two-dimensional image analysis for all galaxies with a
direct black hole (BH) mass determination. As expected, NIR bulge luminosities
Lbul and BH masses are tightly correlated, and if we consider only those
galaxies with secure BH mass measurement and accurate Lbul (27 objects), the
spread of MBH-Lbul is similar to MBH-sigma, where sigma is the effective
stellar velocity dispersion. We find an intrinsic rms scatter of ~0.3 dex in
log MBH. By combining the bulge effective radii R_e measured in our analysis
with sigma, we find a tight linear correlation (rms ~ 0.25 dex) between MBH and
the virial bulge mass (propto R_e sigma^2), with <MBH/Mbul> ~ 0.002. A partial
correlation analysis shows that MBH depends on both sigma and R_e, and that
both variables are necessary to drive the correlations between MBH and other
bulge properties.


title: 9C: A Survey of Radio Sources at 15 GHz with the Ryle Telescope

abstract:
  The fields chosen for the first observations of the cosmic microwave
background with the Very Small Array have been surveyed with the Ryle Telescope
at 15 GHz. We have covered three regions around RA 00h20m Dec +30deg, RA 09h40m
Dec +32deg and RA 15h40m Dec +43deg (J2000), an area of 520 deg^2. There are
465 sources above the current completeness limit of approximately 25 mJy,
although a total of ~760 sources have been detected, some as faint as 10 mJy.
This paper describes our techniques for observation and data analysis; it also
includes source counts and some discussion of spectra and variability.
Preliminary source lists are presented.


title:
Recovery of transverse velocities of steadily rotating patterns in flat
  galaxies

abstract:
  The transverse velocities of steadily rotating, non--axisymmetric patterns in
flat galaxies may be determined by a purely kinematical method, using two
dimensional maps of a tracer surface brightness and radial current density. The
data--maps could be viewed as the zeroth and first velocity moments of the
line--of--sight velocity distribution, which is the natural output of
integral--field spectrographs. Our method is closely related to the
Tremaine--Weinberg method of estimating pattern speeds of steadily rotating
patterns, when the tracer surface brightness satisfies a source--free
continuity equation. We prove that, under identical assumptions about the
pattern, two dimensional maps may be used to recover not just one number (the
pattern speed), but the full vector field of tracer flow in the disc plane. We
illustrate the recovery process by applying it to simulated data, and test its
robustness by including the effects of noise.


title: K-essence and the coincidence problem

abstract:
  K-essence has been proposed as a possible means of explaining the coincidence
problem of the Universe beginning to accelerate only at the present epoch. We
carry out a comprehensive dynamical systems analysis of the k-essence models
given so far in the literature. We numerically study the basin of attraction of
the tracker solutions and we highlight the behaviour of the field close to
sound speed divergences. We find that, when written in terms of parameters with
a simple dynamical interpretation, the basins of attraction represent only a
small region of the phase space.


title:
Three-component modeling of C-rich AGB star winds. II. The effects of
  drift in long-period variables

abstract:
  We present three-component wind models for carbon rich pulsating AGB stars.
In particular we study the effects of drift in models of long-period variables,
meaning that the dust is allowed to move relative to the gas (drift models). In
addition we investigate the importance of the degree of variability of the wind
structures. The wind model contains separate conservation laws for each of the
three components of gas, dust and the radiation field. We use two different
representations for the gas opacity, resulting in models with different gas
densities in the wind. The effects which we investigate here are important for
the understanding of the wind mechanism and mass loss of AGB stars. This study
is hereby a necessary step towards more reliable interpretations of
observations. We find that the effects of drift generally are significant. They
cannot be predicted from models calculated without drift. Moreover, the
non-drift models showing the lowest mass loss rates, outflow velocities, and
the smallest variability in the degree of condensation do not form drift model
winds. The wind formation in drift models is, except for a few cases, generally
less efficient and the mass loss consequently lower than in the corresponding
non-drift models. The effects of drift are generally larger in the more
realistic models using that representation of the gas opacity which results in
lower densities. The outflow properties of these models are also -- for all
cases we have studied -- sensitive to the period of the stellar pulsations. A
check of the mass loss rates against a (recent) fit formula shows
systematically lower values, in particular in the more realistic models with a
low density. The fit is in its current form inapplicable to the new models
presented here.


title:
Uncovering the Beast: Discovery of Embedded Massive Stellar Clusters in
  W49A

abstract:
  We present subarcsecond J, H, and Ks images (FWHM ~ 0.5") of an unbiased 5'x
5' (16pc x 16pc) survey of the densest region of the W49 giant molecular cloud.
The observations reveal 4 massive stellar clusters (with stars as massive as
\~120 Msun), the larger (Cluster 1) about 3 pc East of the well known Welch
ring of ultra-compact Hii regions. Cluster 1 is a) extincted by at least Av >
20 mag of foreground (unrelated and local) extinction, b) has more than 30 mag
of internal inhomogeneous visual extinction implying that it is still deeply
buried in its parental molecular cloud, and c) is powering a 6 pc diameter
giant Hii region seen both at the NIR and radio continuum. We also identify the
exciting sources of several UCHii regions. The census of massive stars in W49A
agrees or is slightly overabundant when compared with the number of Lyman
continuum photons derived from radio observations. We argue that although the
formation of the Welch ring could have been triggered by Cluster 1, the entire
W49A starburst region seems to have been multi-seeded instead of resulting from
a coherent trigger.


title: First Stars Contribution to the Near Infrared Background Fluctuations

abstract:
  We show that the emission from the first, metal-free stars inside Population
III objects (PopIIIs) are needed to explain the level of fluctuations in the
Near Infrared Background (NIRB) recently discovered by Kashlinsky et al.
(2002), at least at the shortest wavelengths. Clustering of (unresolved) Pop
IIIs can in fact account for the entire signal at almost all the ~1-30 arcsec
scales probed by observations in the J band. Their contribution fades away at
shorter frequencies and becomes negligible in the K band. ``Normal'', highly
clustered, <z>~3 galaxies undergoing intense star-formation such as those found
in the Hubble Deep Fields can 'fill in' this gap and provide for the missing
signal. It is in fact found that their contribution to the intensity
fluctuations is the dominant one at lambda=2.17 mum, while it gradually looses
importance in the H and J bands. The joint contribution from these two
populations of cosmic objects is able, within the errors, to reproduce the
observed power spectrum in the whole Near Infrared range on small angular
scales (theta < 200" for Pop III protogalaxies). Signals on larger scales
detected by other experiments instead require the presence of more local
sources.


title: Effective degrees of freedom during the radiation era

abstract:
  We update the curves of the effective degrees of freedom for the energy
density $g_*(T)$ and for the entropy density $g_{*S}(T)$ during the era of
radiation domination in the Universe. We find that a plain count of effective
degrees of freedom sets an upper limit to the temperature of the quark-hadron
transition at $T_c< 235$ MeV for the energy density and $T_c< 245$ MeV for the
entropy density.


title:
Detailed Analysis of Nearby Bulgelike Dwarf Stars III. Alpha and
  Heavy-element abundances

abstract:
  The present sample of nearby bulgelike dwarf stars has kinematics and
metallicities characteristic of a probable inner disk or bulge origin. Ages
derived by using isochrones give 10-11 Gyr for these stars and metallicities
are in the range -0.80< [Fe/H]< +0.40. We calculate stellar parameters from
spectroscopic data, and chemical abundances of Mg, Si, Ca, Ti, La, Ba, Y, Zr
and Eu are derived by using spectrum synthesis.
  We found that [alpha-elements/Fe] show different patterns depending on the
element. Si, Ca and Ti-to-iron ratios decline smoothly for increasing
metallicities, and follow essentially the disk pattern. O and Mg, products of
massive supernovae, and also the r-process element Eu, are overabundant
relative to disk stars, showing a steeper decline for metallicities [Fe/H] >
-0.3 dex. [s-elements/Fe] roughly track the solar values with no apparent trend
with metallicity for [Fe/H] < 0, showing subsolar values for the metal rich
stars. Both kinematical and chemical properties of the bulgelike stars indicate
a distinct identity of this population when compared to disk stars.


title: The interstellar oxygen-K absorption edge as observed by XMM-Newton

abstract:
  High resolution X-ray spectra of the Reflection Grating Spectrometer (RGS) on
board the XMM satellite are used to resolve the oxygen K absorption edge. By
combining spectra of low and high extinction sources, the observed absorption
edge can be split in the true interstellar (ISM) extinction and the
instrumental absorption. The detailed ISM edge structure closely follows the
edge structure of neutral oxygen as derived by theoretical R-matrix
calculations. However, the position of the theoretical edge requires a
wavelength shift. In addition the detailed instrumental RGS absorption edge
structure is presented. All results are verified by comparing to a subset of
Chandra LETG-HRC observations.


title:
Microlensing limits on numbers and orbits of extra-solar planets from
  the 1998-2000 OGLE events

abstract:
  We analyze three years (1998-2000) of OGLE observations of microlensing
events to place limits on the abundance of planets with a planet-to-star mass
ratio $q=10^{-3}$ at distances $\sim 1-4$AU from their host stars, i.e. `cool
Jupiters'. We fit a total of 145 events using a maximum likelihood fit that
adjusts 6 parameters. Each data point on the lightcurve allows us to exclude
planets close to the two images of the source appearing on opposite sides of
the Einstein ring of the lens star. We proceed to compute detection probability
maps for each event, using $\Delta\chi^2$ threshold values of 25, 60, 100 and
combine the results from all events to place global constraints. Our selection
criteria returned 5 candidate events for a planet with mass ratio $q=10^{-3}$.
Only two of these remained as plausible candidates after three were rejected
due to poor data quality at the time of the anomalies. Our results suggest that
less than 21 ($n$)% of the lens stars have Jupiter-mass planets orbiting them
at an orbital radius of $1 < a < 4$ AU. $n \le 2$ is the number of planet
anomaly candidates that are actually due to planets. The datasets presented
here were obtained from the DoPhot analysis of the events available at the OGLE
website. The main conclusion of this work is that observing time is more
efficiently allocated by observing many events with sampling intervals that
produce non-overlapping detection zones than using intensive sampling on a
small number of events.


title: Pixel lensing observations towards globular clusters

abstract:
  It has been suggested that a monitoring program employing the pixel lensing
method to search for microlensing events towards galactic globular clusters may
increase the statistics and discriminate among different halo models.
Stimulated by this proposal, we evaluate an upper limit to the pixel lensing
event rate for such a survey. Four different dark halo models have been
considered changing both the flattening and the slope of the mass density
profile. The lenses mass function has been modelled as a homogenous power - law
for $\mu \in (\mu_l, \mu_u)$ and both the mass limits and the slope of the mass
function have been varied to investigate their effect on the rate. The target
globular clusters have been selected in order to minimize the disk contribution
to the event rate. We find that a pixel lensing survey towards globular
clusters is unable to discriminate among different halo models since the number
of detectable events is too small to allow any reliable statistical analysis.


title:
Linear Polarization in Gamma-Ray Bursts: The Case for an Ordered
  Magnetic Field

abstract:
  Linear polarization at the level of $\sim 1-3%$ has by now been measured in
several gamma-ray burst afterglows. Whereas the degree of polarization, $P$,
was found to vary in some sources, the position angle, $\theta_p$, was roughly
constant in all cases. Until now, the polarization has been commonly attributed
to synchrotron radiation from a jet with a tangled magnetic field that is
viewed somewhat off axis. However, this model predicts either a peak in $P$ or
a $90^\circ$ change in $\theta_p$ around the ``jet break'' time in the
lightcurve, for which there has so far been no observational confirmation. We
propose an alternative interpretation, wherein the polarization is attributed,
at least in part, to a large-scale, ordered magnetic field in the ambient
medium. The ordered component may dominate the polarization even if the total
emissivity is dominated by a tangled field generated by postshock turbulence.
In this picture, $\theta_p$ is roughly constant because of the uniformity of
the field, whereas $P$ varies as a result of changes in the ratio of the
ordered-to-random mean-squared field amplitudes. We point out that variable
afterglow light curves should be accompanied by a variable polarization. The
radiation from the original ejecta, which includes the prompt gamma-ray
emission and the emission from the reverse shock (the `optical flash' and
`radio flare'), could potentially exhibit a high degree of polarization (up to
$\sim 60%$) induced by an ordered transverse magnetic field advected from the
central source.


title: A study of HI-selected galaxies in the Hercules cluster

abstract:
  The present study is aimed at a sample of 22 galaxies detected in the blind
VLA HI survey of the Hercules cluster by Dickey (1997), 18 of which were
selected on an HI line width smaller than 270 km/s and 4 others with only
tentative optical counterparts on the Palomar Sky Survey. Sensitive single-dish
HI line spectra were obtained for 20 of them, and for one (47-154) the VLA
detection was not confirmed. Optical surface photometry was obtained of 10
objects, for 8 of which optical spectroscopy was obtained as well. Based on
various selection criteria, two (ce-143 and ne-204) can be classified as
dwarfs. The objects of which optical observations were made show star formation
properties similar to those of published samples of actively star forming
galaxies, and approximately half of them have properties intermediate between
those of dwarf galaxies and low-luminosity disc galaxies. No optical redshifts
could be obtained for two of the galaxies (sw-103 and sw-194) and their
physical association with the HI clouds detected at their positions therefore
remains uncertain. Unique among the objects is the Tidal Dwarf Galaxy ce-061 in
a tail of the IC 1182 merger system.


title:
Statistical Test of Optical Fibers for use in PMAS, the Potsdam
  Multi-Aperture Spectrophotometer

abstract:
  Focal ratio degradation measurements of optical fibers for the PMAS integral
field instrument have been performed using the Photometric Testbench of the
Potsdam Astrophysical Institute (AIP). An effort has been made to obtain
sufficiently large statistical samples of individual fiber measurements. The
optimization of the measurement process has made it possible to study
quantitatively the effects of different coupling methods (air--glass vs.\
immersion) and of imperfections like defocus, lateral displacement, and angular
misalignment. Furthermore, the effects of mechanical stress on focal ratio
degradation have been investigated, confirming the presumed cause of modal
noise which is known to limit the maximum signal-to-noise one can achieve with
fiber-coupled echelle spectrographs.


title: The Mid-Infrared Spectrum of the Zodiacal and Exozodiacal Light

abstract:
  The zodiacal light is the dominant source of the mid-infrared sky brightness
seen from Earth, and exozodiacal light is the dominant emission from planetary
and debris systems around other stars. We observed the zodiacal light spectrum
with ISOCAM over 5-16 over a wide range of orientations relative to the Sun and
the ecliptic. We present theoretical models for a wide range of particle size
distributions and compositions. The observed temperature is as expected for
large (>10 um radius), low-albedo (< 0.08), rapidly-rotating, grey particles 1
AU from the Sun. In addition to the continuum, we detect a weak excess in the
9-11 um range, with an amplitude of 6% of the continuum. The shape of the
feature can be matched by a mixture of silicates: amorphous forsterite/olivine,
dirty crystalline olivine, and a hydrous silicate (montmorillonite). The
presence of hydrous silicate suggests the parent bodies of those particles were
formed in the inner solar nebula. Large particles dominate the size
distribution, but at least some small particles (radii ~1 um) are required to
produce the silicate emission feature. To compare the properties of zodiacal
dust to dust around other main sequence stars, we reanalyzed the exozodiacal
light spectrum for Beta Pic. The exozodiacal spectra are dominated by cold
dust, with emission peaking in the far-infrared, while the zodiacal spectrum
peaks around 20 um. The shape of the silicate feature from Beta Pic is nearly
identical to that derived from the ISO spectrum of 51 Oph; both exozodiacal
features are very different from that of the zodiacal light. The exozodiacal
features are roughly triangular, peaking at 10.3 um while the zodiacal feature
is more boxy.


title: Ghosts of the Milky Way: a search for topology in new quasar catalogues

abstract:
  We revisit the possibility that we inhabit a compact multi-connected flat, or
nearly-flat, Universe. Analysis of COBE data has shown that, for such a case,
the size of the fundamental domain must be a substantial fraction of the
horizon size. Nevertheless, there could be several copies of the Universe
within the horizon. If the Milky Way was once a quasar we might detect its
`ghost' images. Using new large quasar catalogues we repeat the search by
Fagundes & Wichoski for antipodal quasar pairs. By applying linear theory to
account for the peculiar velocity of the local group, we are able to narrow the
search radius to 134 arcsec. We find seven candidate antipodal quasar pairs
within this search radius. However, a similar number would be expected by
chance. We argue that, even with larger quasar catalogues, and more accurate
values of the cosmological parameters, it is unlikely to be possible to
identify putative ghost pairs unambiguously, because of the uncertainty of the
correction for peculiar motion of the Milky Way.


title:
Observations of HI Absorbing Gas in Compact Radio Sources at
  Cosmological Redshifts

abstract:
  We present an overview of the occurrence and properties of atomic gas
associated with compact radio sources at redshifts up to z=0.85. Searches for
HI 21cm absorption were made with the Westerbork Synthesis Radio Telescope at
UHF-high frequencies (725-1200 MHz). Detections were obtained for 19 of the 57
sources with usable spectra (33%). We have found a large range in line depths,
from tau=0.16 to tau<=0.001. There is a substantial variety of line profiles,
including Gaussians of less than 10km/s, to more typically 150km/s, as well as
irregular and multi-peaked absorption profiles, sometimes spanning several
hundred km/s. Assuming uniform coverage of the entire radio source, we obtain
column depths of atomic gas between 1e19 and 3.3e21(Tsp/100K)(1/f)cm^(-2).
There is evidence for significant gas motions, but in contrast to earlier
results at low redshift, there are many sources in which the HI velocity is
substantially negative (up to v=-1420km/s) with respect to the optical
redshift, suggesting that in these sources the atomic gas, rather than falling
into the centre, may be be flowing out, interacting with the jets, or rotating
around the nucleus.


title: Halo Substructure And The Power Spectrum

abstract:
  (ABRIDGED) We present a semi-analytic model to explore merger histories,
destruction rates, and survival probabilities of substructure in dark matter
halos and use it to study the substructure populations of galaxy-sized halos as
a function of the power spectrum. We successfully reproduce the subhalo
velocity function and radial distribution seen in N-body simulations for
standard LCDM. We explore the implications of spectra with normalizations and
tilts spanning sigma_8 = 0.65-1 and n = 0.8-1. We also study a running index
(RI) model with dn/dlnk=-0.03, as discussed in the first year WMAP report, and
several WDM models with masses m_W = 0.75, 1.5, 3.0 keV. The substructure mass
fraction is relatively insensitive to the tilt and overall normalization of the
power spectrum. All CDM-type models yield projected substructure mass fractions
that are consistent with, but on the low side of, estimates from strong lens
systems: f = 0.4-1.5% (64 percentile) in systems M_sub < 10^9 Msun. Truncated
models produce significantly smaller fractions and are disfavored by lensing
results. We compare our predicted subhalo velocity functions to the dwarf
satellite population of the Milky Way. Assuming isotropic velocity dispersions,
we find the standard n=1 model overpredicts the number of MW satellites as
expected. Models with less small-scale power are more successful because there
are fewer subhalos of a given circular velocity and the mapping between
observed velocity dispersion and halo circular velocity is markedly altered.
The RI model, or a fixed tilt with sigma_8=0.75, can account for the MW dwarfs
without the need for differential feedback; however, these comparisons depend
sensitively on the assumption of isotropic velocities in satellite galaxies.


title: Revisiting the location and environment of the central engine in NGC1068

abstract:
  We revisit in this paper the location of the various components observed in
the AGN of NGC1068. Discrepancies between previously published studies are
explained, and a new measurement for the absolute location of the K-band
emission peak is provided. It is found to be consistent with the position of
the central engine as derived by Gallimore (1997), Capetti (1997) and Kishimoto
(1999). A series of map overlays is then presented and discussed. Model
predictions of dusty tori show that the nuclear unresolved NIR-MIR emission is
compatible with a broad range of models: the nuclear SED alone does not
strongly constrain the torus geometry, while placing reasonable constraints on
its size and thickness. The extended MIR emission observed within the ionizing
cone is shown to be well explained by the presence of optically thick dust
clouds exposed to the central engine radiation and having a small covering
factor. Conversely, a distribution of diffuse dust particles within the
ionizing cone is discarded. A simple model for the H2 and CO emission observed
perpendicularly to the axis of the ionizing cone is proposed. We show that a
slight tilt between the molecular disc and the Compton thick central absorber
naturally reproduces the observed distribution of H2 of CO emission.


title: The BIMA Survey of Nearby Galaxies (BIMA SONG). II. The CO Data

abstract:
  The BIMA Survey of Nearby Galaxies is a systematic imaging study of the 3 mm
CO J = 1--0 molecular emission within the centers and disks of 44 nearby spiral
galaxies. The typical spatial resolution of the survey is 6", or 360 pc at the
average distance (12 Mpc) of the sample, over a field of view of 10kpc. The
velocity resolution of the CO observations is 4 km/s. The sample was not chosen
based on CO or infrared brightness; instead, all spirals were included that met
the selection criteria of vsun <= 2000 km/s, dec >= -20deg, inc <= 70deg, D25 <
70', and BT < 11.0. The detection rate was 41/44 sources or 93%. Fully-sampled
single-dish CO data were incorporated into the maps for 24 galaxies; these
single-dish data comprise the most extensive collection of fully-sampled,
two-dimensional single-dish CO maps of external galaxies to date. We also
tabulate direct measurements of the global CO flux densities for these 24
sources. We demonstrate that the measured ratios of flux density recovered are
a function of the signal-to-noise of the interferometric data. We examine the
degree of central peakedness of the molecular surface density distributions and
show that the distributions exhibit their brightest CO emission within the
central 6" in only 20/44 or 45% of the sample. We show that all three Local
Group spiral galaxies have CO morphologies that are represented in SONG, though
the Milky Way CO luminosity is somewhat below the SONG average, and M31 and M33
are well below average. This survey provides a unique public database of
integrated intensity maps, channel maps, spectra, and velocity fields of
molecular emission in nearby galaxies.


title:
Evidence of TeV gamma-ray emission from the nearby starburst galaxy NGC
  253

abstract:
  TeV gamma-rays were recently detected from the nearby normal spiral galaxy
NGC 253 (Itoh et al., 2002). Observations to detect the Cherenkov light images
initiated by gamma-rays from the direction of NGC 253 were carried out in 2000
and 2001 over a total period of $\sim$150 hours. The orientation of images in
gamma-ray--like events is not consistent with emission from a point source, and
the emission region corresponds to a size greater than 10 kpc in radius. Here,
detailed descriptions of the analysis procedures and techniques are given.


title: J-type Carbon Stars in the Large Magellanic Cloud

abstract:
  A sample of 1497 carbon stars in the Large Magellanic Cloud has been observed
in the red part of the spectrum with the 2dF facility on the AAT. Of these, 156
have been identified as J-type (i.e. 13C-rich) carbon stars using a technique
which provides a clear distinction between J stars and the normal N-type carbon
stars that comprise the bulk of the sample, and yields few borderline cases. A
simple 2-D classification of the spectra, based on their spectral slopes in
different wavelength regions, has been constructed and found to be related to
the more conventional c- and j-indices, modified to suit the spectral regions
observed. Most of the J stars form a photometric sequence in the K - (J-K)
colour magnitude diagram, parallel to and 0.6 mag fainter than the N star
sequence. A subset of the J stars (about 13 per cent) are brighter than this J
star sequence; most of these are spectroscopically different from the other J
stars. The bright J stars have stronger CN bands than the other J stars and are
found strongly concentrated in the central regions of the LMC. Most of the
rather few stars in common with Hartwick and Cowley's sample of suspected CH
stars are J stars. Overall, the proportion of carbon stars identified as J
stars is somewhat lower than has been found in the Galaxy. The Na D lines are
weaker in the LMC J stars than in either the Galactic J stars or the LMC N
stars, and do not seem to depend on temperature.


title: Lithium in LMC carbon stars

abstract:
  Nineteen carbon stars that show lithium enrichment in their atmospheres have
been discovered among a sample of 674 carbon stars in the Large Magellanic
Cloud. Six of the Li-rich carbon stars are of J-type, i.e. with strong 13C
isotopic features. No super-Li-rich carbon stars were found. The incidence of
lithium enrichment among carbon stars in the LMC is much rarer than in the
Galaxy, and about five times more frequent among J-type than among N-type
carbon stars. The bolometric magnitudes of the Li-rich carbon stars range
between -3.3 and -5.7. Existing models of Li-enrichment via the hot bottom
burning process fail to account for all of the observed properties of the
Li-enriched stars studied here.


title:
Dynamical bar-mode instability of differentially rotating stars: Effects
  of equations of state and velocity profiles

abstract:
  As an extension of our previous work, we investigate the dynamical
instability against nonaxisymmetric bar-mode deformations of differentially
rotating stars in Newtonian gravity varying the equations of state and velocity
profiles. We performed the numerical simulation and the followup linear
stability analysis adopting polytropic equations of state with the polytropic
indices n=1, 3/2, and 5/2 and with two types of angular velocity profiles (the
so-called j-constant-like and Kepler-like laws). It is confirmed that rotating
stars of a high degree of differential rotation are dynamically unstable
against the bar-mode deformation, even for the ratio of the kinetic energy to
the gravitational potential energy $\beta$ of order 0.01. The criterion for
onset of the bar-mode dynamical instability depends weakly on the polytropic
index n and the angular velocity profile as long as the degree of differential
rotation is high. Gravitational waves from the final nonaxisymmetric
quasi-stationary states are calculated in the quadrupole formula. For
proto-neutron stars of mass $1.4M_{\odot}$, radius $\sim 30$ km and $\beta \alt
0.1$, such gravitational waves have the frequency of $\sim$ 600--1,400 Hz, and
the effective amplitude is larger than $10^{-22}$ at a distance of about 100
Mpc irrespective of n and the angular velocity profile.


title:
Linear Stability Analysis of Differentially Rotating Polytropes -- New
  results for the m = 2 f-mode dynamical instability --

abstract:
  We have studied the $f$-mode oscillations of differentially rotating
polytropes by making use of the linear stability analysis. We found that the
critical values of $T/|W|$ where the dynamical instability against the $m = 2$
$f$-mode oscillations sets in decrease down to $T/|W| \sim 0.20$ as the degree
of differential rotation becomes higher. Here $m$ is an azimuthal mode number
and $T$ and $W$ are the rotational energy and the gravitational potential
energy, respectively. This tendency is almost independent of the
compressibility of the polytropes. These are the {\it first exact results} of
the linear stability analysis for the occurrence of the dynamical instability
against the $m = 2$ $f$-modes.


title:
Importance of Perturbed Gravitational Potentials in Differentially
  Rotating Newtonian Stars

abstract:
  It is usually believed that the Cowling approximation can give satisfactory
solutions if the stars %are highly compressible have soft equations of state
and/or if the strongly general relativistic stars are treated in the case of
rigid rotation. Since, however, there have been no systematic studies about the
accuracy of the Cowling approximation for differentially rotating compressible
stars, we investigate eigenfrequencies and eigenfunctions of the oscillation
modes in {\it rapidly} and {\it differentially} rotating compressible stars by
employing the exact method including full-perturbations and the Cowling
approximation.
  We have found that the Cowling approximation for f-mode oscillations is not a
good approximation in rapidly and differentially rotating stars, although rapid
rotation makes this approximation better for rigidly rotating stars. This
result suggests that we must be careful when we apply the Cowling approximation
to differentially rotating stars even in the framework of general relativity.
On the other hand, the approximation will work well for r-modes even if the
star is rotating differentially. Therefore, the Cowling approximation can be
used as a strong tool for the investigation of r-mode oscillations in the
general relativistic framework that it is difficult to compute including the
perturbations of gravity.


title: Is Galaxy Distribution Non-extensive and Non-Gaussian?

abstract:
  Self gravitating systems (SGS) in the Universe are generally thought to be
non-extensive, and often show long-tails in various distribution functions. In
principle, these non-Boltzmann properties are naturally expected from the
peculiar property of gravity, long-range and unshielded. Therefore the ordinary
Boltzmann statistical mechanics would not be applicable for these self
gravitating systems (SGS) in its naive form. In order to step further, we
quantitatively investigate the above two properties, non-extensivity and
long-tails, by explicitly introducing various models of statistical mechanics.
We use the data of CfA II South redshift survey and apply the count-in-cell
method. We study four statistical mechanics, (1) Boltzmann, (2) Fractal, (3)
R\'enyi, and (4) Tsallis, and use Akaike information criteria (AIC) for the
fair comparison.


title: An X-ray Image of the Composite SNR G16.7+0.1

abstract:
  We have observed the Galactic supernova remnant G16.7+0.1 for 13 ks using the
EPIC cameras aboard the XMM-Newton X-ray Observatory, producing the first X-ray
image of the remnant. This composite radio remnant has a core radio flux
density of only 100 mJy, making it one of the faintest radio synchrotron
nebulae yet detected, although the core-to-shell flux ratio at 6 cm is typical
of the growing class of composite remnants. Our image is seriously contaminated
by bright arcs produced by singly reflected X-rays from the X-ray binary GX17+2
which lies just outside the field of view, providing an interesting data
analysis challenge. Nonetheless, the remnant's synchrotron core is clearly
detected. We report on the spectrum and intensity of the core emission as well
as on our search for emission from the thermal shell, and describe the
constraints these observations provide on the remnant's distance, age, and
central pulsar properties.


title:
Building Blocks in Hierarchical Clustering Scenarios and their
  Connection with Damped Ly$\alpha$ Systems

abstract:
  We carried out a comprehensive analysis of the chemical properties of the
interstellar medium (ISM) and the stellar population (SP) of current normal
galaxies and their progenitors in a hierarchical clustering scenario. We
compared the results with observations of Damped Lyman-$\alpha$ systems (DLAs)
under the hypothesis that, at least, part of the observed DLAs could originate
in the building blocks of today normal galaxies. We used a hydrodynamical
cosmological code which includes star formation and chemical enrichment.
Galaxy-like objects are identified at $z=0$ and then followed back in time.
Random line-of-sights (LOS) are drawn through these structures in order to
mimic Damped Lyman $\alpha$ systems. We then analysed the chemical properties
of the ISM and SP along the LOS. We found that the progenitors of current
galaxies in the field with mean $L <0.5 L^* $ and virial circular velocity of
$100-250 {\rm km/sec}$ could be the associated DLA galaxies. For these systems
we detected a trend for $<L/L^*>$ to increase with redshift.(Abridged)


title:
Slow evolution of elliptical galaxies induced by dynamical friction. I.
  Capture of a system of satellites

abstract:
  The main goal of this paper is to set up a numerical laboratory for the study
of the slow evolution of the density and of the pressure tensor profiles of an
otherwise collisionless stellar system, as a result of the interactions with a
minority component of heavier "particles".The effects that we would like to
study are those attributed to slow collisional relaxation and generically
called "dynamical friction". We start by revisiting the problem of the sinking
of a satellite inside an initially isotropic, non-rotating, spherical galaxy,
which we follow by means of N-body simulations using about one million
particles. We then consider a quasi-spherical problem, in which the satellite
is fragmented into a set of many smaller masses with a spherically symmetric
initial density distribution. In a wide set of experiments, designed in order
to bring out effects genuinely associated with dynamical friction, we are able
to demonstrate the slow evolution of the density profile and the development of
a tangentially biased pressure in the underlying stellar system, while we
briefly address the issue of the circularization of orbits induced by dynamical
friction on the population of fragments. The results of the simulations
presented here and others planned for future investigations allow us to study
the basic mechanisms of slow relaxation in stellar systems and thus may be of
general interest for a variety of problems, especially in the cosmological
context. Here our experiments are conceived with the specific goal to clarify
some mechanisms that may play a role in the evolution of an elliptical galaxy
as a result of the interaction between the stars and a significant population
of globular clusters or of the merging of a large number of small satellites.


title:
The Presence and Distribution of HI Absorbing Gas in Sub-galactic Sized
  Radio Sources

abstract:
  We consider the incidence of HI absorption in intrinsically small
sub-galactic sized extragalactic sources selected from sources classified as
Gigahertz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) sources. We
find that the smaller sources (<0.5 kpc) have larger HI column densities than
the larger sources (>0.5 kpc). Both a spherical and an axi-symmetric gas
distribution, with a radial power law density profile, can be used to explain
this anti-correlation between projected linear size and HI column density.
Since most detections occur in objects classified as galaxies, we argue that if
the unified schemes apply to GPS/CSSs a disk distribution for the HI is more
likely. The most favoured explanation for the compact sizes of the GPS/CSSs is
that they are young sources evolving in a power law density medium. For the
GPSs with measured expansion velocities, our derived densities are within an
order of magnitude of those estimated from ram-pressure confinement of the
lobes assuming equipartition. Our results therefore support the youth model.


title: electron-positron-photon plasma around a collapsing star

abstract:
  We describe electron-positron pairs creation around an electrically charged
star core collapsing to an electromagnetic black hole (EMBH), as well as pairs
annihilation into photons. We use the kinetic Vlasov equation formalism for the
pairs and photons and show that a regime of plasma oscillations is established
around the core. As a byproduct of our analysis we can provide an estimate for
the thermalization time scale.


title: Plasma expansion in the geometry of a collapsing star

abstract:
  We describe the evolution of an electron-positron-photon plasma created by
Sauter--Heisenberg--Euler--Schwinger mechanism around a collapsing charged star
core in the Reissner-Nordstr\"{o}m geometry external to the core, in view of
the application in the framework of the EMBH theory for gamma ray bursts.


title: XMM-Newton observations expose AGN in apparently normal galaxies

abstract:
  We have performed a detailed analysis of 3 optically normal galaxies
extracted from the XMM Bright Serendipitous Source Sample. Thanks to the good
statistics of the XMM-Newton data, we have unveiled the presence of an AGN in
all of them. In particular, we detect both X-ray obscured (N_H>10^{22} cm^{-2})
and unobscured (N_H<10^{22} cm^{-2}) AGN with intrinsic 2--10 keV luminosities
in the range between 10^{42} -- 10^{43} erg s^{-1}. We find that the X-ray and
optical properties of the sources discussed here could be explained assuming a
standard AGN hosted by galaxies with magnitudes M_R<M^*, taking properly into
account the absorption associated with the AGN, the optical faintness of the
nuclear emission with respect to the host galaxy, and the inadequate set--up
and atmospheric conditions during the optical spectroscopic observations. Our
new spectroscopic observations have revealed the expected AGN features also in
the optical band. These results clearly show that optical spectroscopy
sometimes can be inefficient in revealing the presence of an AGN, which instead
is clearly found from an X-ray spectroscopic investigation. This remarks the
importance of being careful in proposing the identification of X-ray sources
(especially at faint fluxes) when only low quality optical spectra are in hand.
This is particularly important for faint surveys (such as those with XMM-Newton
and Chandra), in which optically dull but X-ray active objects are being found
in sizeable numbers.


title: Explanatory Supplement of the ISOGAL-DENIS Point Source Catalogue

abstract:
  We present version 1.0 of the ISOGAL-DENIS Point Source Catalogue (PSC),
containing more than 100,000 point sources detected at 7 and/or 15 micron in
the ISOGAL survey of the inner Galaxy with the ISOCAM instrument on board the
Infrared Space Observatory (ISO). These sources are cross-identified, wherever
possible, with near-infrared (0.8-2.2 micron) data from the DENIS survey. The
overall surface covered by the ISOGAL survey is about 16 square degrees, mostly
(95%) distributed near the Galactic plane (|b| < 1 deg), where the source
extraction can become confusion limited and perturbed by the high background
emission. Therefore, special care has been taken aimed at limiting the
photometric error to ~0.2 magnitude down to a sensitivity limit of typically 10
mJy. The present paper gives a complete description of the entries and the
information which can be found in this catalogue, as well as a detailed
discussion of the data processing and the quality checks which have been
completed. The catalogue is available via the VizieR Service at the Centre de
Donn\'ees Astronomiques de Strasbourg (CDS,
http://vizier.u-strasbg.fr/viz-bin/VizieR/) and also via the server at the
Institut d'Astrophysique de Paris (http://www-isogal.iap.fr/). A more complete
version of this paper, including a detailed description of the data processing,
is available in electronic form through the ADS service.


title: Chandra Observation of the Merging Cluster Abell 2034

abstract:
  We present an analysis of a Chandra observation of Abell 2034. The cluster
has multiple signatures of an ongoing merger, including a cold front and
probable significant heating of the intracluster medium above its equilibrium
temperature. We find no evidence for the large cooling rate previously
determined for the cluster, and in fact find it to be roughly isothermal,
though with numerous small-scale inhomogeneities, out to a radius of ~700 kpc.
The cold front appears to be in the process of being disrupted by gas dynamic
instability and perhaps by shock heating. We find weak evidence for Inverse
Compton hard X-ray emission from the radio relic suspected to be associated
with the cold front. Finally, we study the emission to the south of the
cluster, which was previously thought to be a merging subcluster. We find no
evidence that this "subcluster" is interacting with the main Abell 2034
cluster. On the other hand, the properties of this region are inconsistent with
an equilibrium cluster at the redshift of Abell 2034 or less. We explore the
possibility that it is a disrupted merging subcluster, but find its luminosity
to be significantly lower than expected for such a scenario. We suggest that
the emission to the south of the cluster may actually be a moderate to high
redshift (0.3 < z < 1.25) background cluster seen in projection against Abell
2034.


title:
Stellar tracers of the Cygnus Arm I. Spectroscopic study of bright
  photometric candidates

abstract:
  We present medium-resolution spectroscopy of a sample of stars in the second
Galactic quadrant selected from the literature because their colours suggest
that they are moderately-reddened early-type stars at very large distances.
  From the derived spectral types and observed colours, we calculate distances
to all these objects. For a sizable fraction of our sample, we find distances
well in excess of what is expected for Perseus Arm objects, even allowing for
rather generous errors. In the interval l=150degr-180degr, there is a large
number of objects with distances in excess of 4 kpc, which are likely tracing
the Outer or Cygnus Arm. In particular, we find that the association Cam OB3 is
placed on this Arm. Based on our results, the extent and definition of the
associations Cas OB4 and Aur OB2 need to be reevaluated.


title:
A Cosmic Microwave Background Radiation Polarimeter Using
  Superconducting Bearings

abstract:
  Measurements of the polarization of the cosmic microwave background (CMB)
radiation are expected to significantly increase our understanding of the early
universe. We present a design for a CMB polarimeter in which a cryogenically
cooled half wave plate rotates by means of a high-temperature superconducting
(HTS) bearing. The design is optimized for implementation in MAXIPOL, a
balloon-borne CMB polarimeter. A prototype bearing, consisting of commercially
available ring-shaped permanent magnet and an array of YBCO bulk HTS material,
has been constructed. We measured the coefficient of friction as a function of
several parameters including temperature between 15 and 80 K, rotation
frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm, and
ambient pressure between 10^{-7} and 1 torr. The low rotational drag of the HTS
bearing allows rotations for long periods of time with minimal input power and
negligible wear and tear thus making this technology suitable for a future
satellite mission.


title:
Chemical and spectrophotometric evolution of Low Surface Brightness
  galaxies

abstract:
  Based on the results of recent surveys, we have constructed a relatively
homogeneous set of observational data concerning the chemical and photometric
properties of Low Surface Brightness galaxies (LSBs). We have compared the
properties of this data set with the predictions of models of the chemical and
spectrophotometric evolution of LSBs. The basic idea behind the models, i.e.
that LSBs are similar to 'classical' High Surface Brightness spirals except for
a larger angular momentum, is found to be consistent with the results of their
comparison with these data. However, some observed properties of the LSBs (e.g.
their colours, and specifically the existence of red LSBs) as well as the large
scatter in these properties, cannot be reproduced by the simplest models with
smoothly evolving star formation rates over time. We argue that the addition of
bursts and/or truncations in the star formation rate histories can alleviate
that discrepancy.


title: Resolving the Microlens Mass Degeneracy for Earth-Mass Planets

abstract:
  Of all planet-finding techniques, microlensing is potentially the most
sensitive to Earth-mass planets. However, microlensing lightcurves generically
yield only the planet-star mass ratio: the mass itself is uncertain to a factor
of a few. To determine the planet mass, one must measure both the ``microlens
parallax'' and source-lens relative proper motion. Here we present a new method
to measure microlens masses for terrestrial planets. We show that, with only a
modest adjustment to the proposed orbit of the dedicated satellite that finds
the events, and combined with observations from a ground-based observing
program, the planet mass can be measured routinely. The dedicated satellite
that finds the events will automatically measure the proper motion and one
projection of the ``vector microlens parallax.'' If the satellite is placed in
an L2 orbit, or a highly elliptical orbit around the Earth, the Earth-satellite
baseline is sufficient to measure a second projection of the vector microlens
parallax from the difference in the lightcurves as seen from the Earth and the
satellite as the source passes over the caustic structure induced by the
planet. This completes the mass measurement.


title: A simple model for the clustering of subhalos as a function of mass

abstract:
  Astrophysicists do not associate galaxies with the massive dark matter halos
so easily detected in particle simulations and whose mass function can be
predicted by the Press-Schechter formalism and its variants. Instead, they
associate galaxies with smaller surviving subhalos whose contents do not fully
mix into the larger dark matter halos they exist in. However, these subhalos
are as of now difficult to find in simulations. I present a simple description
of what the Press-Schechter formalism can say about the clustering of these
subhalos, under the restrictive assumption that at fixed subhalo mass, the
chance of survival of the subhalo is independent of its larger scale
environment. This model predicts a weak dependence of clustering on mass below
masses of about 10^12 solar masses, in agreement with observations of a weak
dependence of clustering on luminosity at luminosities less than L*. The model
is in qualitative agreement with observations that at low luminosities galaxy
clustering is a strong function of color while at high luminosities galaxy
clustering is a strong function of luminosity.


title:
Optimal Moments for the Analysis of Peculiar Velocity Surveys II:
  Testing

abstract:
  Analyses of peculiar velocity surveys face several challenges, including low
signal--to--noise in individual velocity measurements and the presence of
small--scale, nonlinear flows. This is the second in a series of papers in
which we describe a new method of overcoming these problems by using data
compression as a filter with which to separate large--scale, linear flows from
small--scale noise that can bias results. We demonstrate the effectiveness of
our method using realistic catalogs of galaxy velocities drawn from N--body
simulations. Our tests show that a likelihood analysis of simulated catalogs
that uses all of the information contained in the peculiar velocities results
in a bias in the estimation of the power spectrum shape parameter $\Gamma$ and
amplitude $\beta$, and that our method of analysis effectively removes this
bias. We expect that this new method will cause peculiar velocity surveys to
re--emerge as a useful tool to determine cosmological parameters.


title: Gravitational Lensing by Burkert Halos

abstract:
  We investigate the gravitational lensing properties of dark matter halos with
Burkert profiles. We derive an analytic expression for the lens equation and
use it to compute the magnification, impact parameter and image separations for
strong lensing. For the scaling relation that provides the best fits to
spiral-galaxy rotation curve data, Burkert halos will not produce strong
lensing, even if this scaling relation extends up to masses of galaxy clusters.
Tests of a simple model of an exponential stellar disk superimposed on a
Burkert-profile halo demonstrate that strong lensing is unlikely without an
additional concentration of mass in the galaxy center (e.g. a bulge). The fact
that most strong lenses on galactic scales are elliptical galaxies suggests
that a strong central concentration of baryons is required to produce image
splitting. This solution is less attractive for clusters of galaxies, which are
generally considered to be dark-matter dominated even at small radii. There are
three possible implications of these results: (1) dark halos may have a variety
of inner profiles (2) dark matter halos may not follow a single scaling
relation from galaxy scale up to cluster scale and/or (3) the splitting of
images (even by clusters of galaxies) may in general be due to the central
concentration of baryonic material in halos rather than dark matter.


title:
The Globular Cluster Luminosity Function: New Progress in Understanding
  an Old Distance Indicator

abstract:
  I review the Globular Cluster Luminosity Function (GCLF) with emphasis on
recent observational data and theoretical progress. As is well known, the
turn-over magnitude (TOM) is a good distance indicator for early-type galaxies
within the limits set by data quality and sufficient number of objects. A
comparison with distances derived from surface brightness fluctuations with the
available TOMs in the V-band reveals, however, many discrepant cases. These
cases often violate the condition that the TOM should only be used as a
distance indicator in old globular cluster systems. The existence of
intermediate age-populations in early-type galaxies likely is the cause of many
of these discrepancies. The connection between the luminosity functions of
young and old cluster systems is discussed on the basis of modelling the
dynamical evolution of cluster systems. Finally, I briefly present the current
ideas of why such a universal structure as the GCLF exists.


title: The Populations of Comet-Like Bodies in the Solar system

abstract:
  A new classification scheme is introduced for comet-like bodies in the Solar
system. It covers the traditional comets as well as the Centaurs and
Edgeworth-Kuiper belt objects. At low inclinations, close encounters with
planets often result in near-constant perihelion or aphelion distances, or in
perihelion-aphelion interchanges, so the minor bodies can be labelled according
to the planets predominantly controlling them at perihelion and aphelion. For
example, a JN object has a perihelion under the control of Jupiter and aphelion
under the control of Neptune, and so on. This provides 20 dynamically distinct
categories of outer Solar system objects in the Jovian and trans-Jovian
regions. The Tisserand parameter with respect to the planet controlling
perihelion is also often roughly constant under orbital evolution. So, each
category can be further sub-divided according to the Tisserand parameter. The
dynamical evolution of comets, however, is dominated not by the planets nearest
at perihelion or aphelion, but by the more massive Jupiter. The comets are
separated into four categories -- Encke-type, short-period, intermediate and
long-period -- according to aphelion distance. The Tisserand parameter
categories now roughly correspond to the well-known Jupiter-family comets,
transition-types and Halley-types. In this way, the nomenclature for the
Centaurs and Edgeworth-Kuiper belt objects is based on, and consistent with,
that for comets.


title: Deriving the Metallicity Distribution Function of Galactic Systems

abstract:
  The chemical evolution of the Milky Way is investigated using a dual-phase
metal-enriched infall model in which primordial gas fuels the earliest epoch of
star formation, followed by the ongoing formation of stars from newly accreted
gas. The latest metallicity distribution of local K-dwarfs is reproduced by
this model, which allows the Galactic thin disk to form from slightly
metal-enriched gas with alpha-element enhancement. Our model predicts ages for
the stellar halo and thin disk of 12.5 and 7.4 Gyr, respectively, in agreement
with empirically determined values. The model presented in this paper is
compared with a similar dual-phase infall model from Chiappini et al. (2001).
We discuss a degeneracy that enables both models to recover the K-dwarf
metallicity distribution while yielding different star formation histories.
  The metallicity distribution function (MDF) of K-dwarfs is proposed to be
more directly comparable to chemical evolution model results than the G-dwarf
distribution because lower mass K-dwarfs are less susceptible to stellar
evolutionary effects. The K-dwarf MDF should consequently be a better probe of
star formation history and provide a stronger constraint to chemical evolution
models than the widely used G-dwarf MDF. The corrections that should be applied
to a G-dwarf MDF are quantified for the case of the outer halo of NGC 5128.


title: Luminosity and Mass Function of the Galactic open cluster NGC 2422

abstract:
  We present UBVRI photometry of the open cluster NGC 2422 (age $\sim 10^8$ yr)
down to a limiting magnitude $V\simeq19$. These data are used to derive the
Luminosity and Mass Functions and to study the cluster spatial distribution. By
considering the color-magnitude diagram data and adopting a representative
cluster main sequence, we obtained a list of candidate cluster members based on
a photometric criterion. Using a reference field region and an iterative
procedure, a correction for contaminating field stars has been derived in order
to obtain the Luminosity and the Mass Functions in the $M=0.4-3.5 M_\odot$
range. By fitting the spatial distribution, we infer that a non-negligible
number of cluster stars lies outside our investigated region. We have estimated
a correction to the Mass Function of the cluster in order to take into account
the "missing" cluster stars. The Present Day Mass Function of \ngc2422 can be
represented by a power-law of index $\alpha = 3.07 \pm0.08 $ (rms) -- the
Salpeter Mass Function in this notation has index $\alpha = 2.35$ -- in the
mass range $ 0.9 \leq M/M_\odot\leq 2.5 $. The index $\alpha$ and the total
mass of the cluster are very similar to those of the Pleiades.


title: XMM-Newton observation of SN1993J in M81

abstract:
  In April 2001 SN1993J was observed with both the PN and MOS cameras of the
XMM-Newton observatory, resulting in about 7. x 10^4 s of acceptable
observation time. Fit results with both the PN and MOS2 camera spectra studying
different spectral models are presented. The spectra are best fitted in the
energy range between 0.3 and 11 keV by a 2-component thermal model with
temperatures of kT_1 = 0.34+-0.04 keV and kT_2 = 6.54+-4 keV, adopting
ionization equilibrium. A fit with a shock model also provides acceptable
results. Combining the XMM-Newton data with former X-ray observations of the
supernova, we discuss the general trend of L_x propto t^{-0.30} and the bump of
the X-ray light curve as well as former and recent spectral results in the
light of the standard SN model as first proposed by Chevalier in 1982.


title: 1RXSJ062518.2+733433: A bright, soft intermediate polar

abstract:
  We present the results of 50 hours time-resolved R-band photometry of the
ROSAT all-sky survey source 1RXSJ062518.2+733433. The source was identified by
Wei et al. (1999) as a cataclysmic variable. Our photometry, performed in 10
nights between February 11, 2003, and March 21, 2003, reveals two stable
periodicities at 19.7874 and 283.118 min, which are identified as probable spin
and orbital periods of the binary. We therefore classify 1RXSJ062518.2+733433
as an intermediate polar. Analysis of the RASS X-ray observations reveal a
variability of 100% in the X-ray flux and a likely soft X-ray excess. The new
IP thus joins the rare group of soft IPs with only four members so far.


title: A deep cluster survey in Chandra archival data. First results

abstract:
  I present the first results of a search for clusters of galaxies in Chandra
ACIS pointed observations at high galactic latitude with exposure times larger
than 10 ks. The survey is being carried out using the Voronoi Tessellation and
Percolation technique, which is particularly suited for the detection and
accurate quantification of extended and/or low surface brightness emission in
X-ray imaging observations. A new catalogue of 36 cluster candidates has been
created from 5.55 square degrees of surveyed area. Five of these candidates
have already been associated to visible enhancements of the projected galaxy
distribution in low deepness DSS-II fields and are probably low-to moderate
redshift systems. Three of the candidates have been identified in previous
ROSAT-based surveys. I show that a significative fraction (30-40%) of the
candidate clusters are probably intermediate to high redshift systems. In this
paper I publish the catalogue of these first candidate clusters. I also derive
the number counts of clusters and compare it with the results of deep
ROSAT-based cluster surveys.


title: WMAP and the Generalized Chaplygin Gas

abstract:
  We compare the WMAP temperature power spectrum and SNIa data to models with a
generalized Chaplygin gas as dark energy. The generalized Chaplygin gas is a
component with an exotic equation of state, p_X=-A/\rho^\alpha_X (a polytropic
gas with negative constant and exponent). Our main result is that, restricting
to a flat universe and to adiabatic pressure perturbations for the generalized
Chaplygin gas, the constraints at 95% CL to the present equation of state w_X =
p_X / \rho_X and to the parameter \alpha are -1\leq w_X < -0.8, 0 \leq \alpha
<0.2, respectively. Moreover, we show that a Chaplygin gas (\alpha =1) as a
candidate for dark energy is ruled out by our analysis at more than the 99.99%
CL. A generalized Chaplygin gas as a unified dark matter candidate
(\Omega_{CDM}=0) appears much less likely than as a dark energy model, although
its \chi^2 is only two sigma away from the expected value.


title: Beam deconvolution in noisy CMB maps

abstract:
  The subject of this paper is beam deconvolution in small angular scale CMB
experiments. The beam effect is reversed using the Jacobi iterative method,
which was designed to solved systems of algebraic linear equations. The beam is
a non circular one which moves according to the observational strategy. A
certain realistic level of Gaussian instrumental noise is assumed. The method
applies to small scale CMB experiments in general (cases A and B), but we have
put particular attention on Planck mission at 100 GHz (cases C and D). In cases
B and D, where noise is present, deconvolution allows to correct the main beam
distortion effect and recover the initial angular power spectrum up to the end
of the fifth acoustic peak. An encouraging result whose importance is analyzed
in detail. More work about deconvolution in the presence of other systematics
is in progress.
  This paper is related to the Planck LFI activities.


title: A simple empirical redshift indicator for gamma-ray bursts

abstract:
  We propose a new empirical redshift indicator for gamma-ray bursts. This
indicator is easily computed from the gamma-ray burst spectral parameters, and
its duration, and it provides ``pseudo-redshifts'' accurate to a factor two.
Possible applications of this redshift indicator are briefly discussed.


title:
Hubble Space Telescope Observations of the Nova-Like Cataclysmic
  Variable V348 Puppis

abstract:
  We present time series UV and optical (1150 -- 8000 A) spectrophotometry of
the novalike (NL) cataclysmic variable V348 Pup through and after eclipse.
Outside of eclipse, the spectrum is characterized by a blue continuum, strong
line emission, and a broad dip from 2000 -- 3000 A. The continuum eclipse depth
is roughly the same over the entire wavelength range covered and there are no
signatures of the WD eclipse in the light curves. Model steady-state accretion
disk spectra provide a poor fit to the shape of the UV-optical spectrum outside
of eclipse. All of these properties are consistent with a disk that is
self-shielding, hiding the inner disk and the white dwarf. In eclipse, the
emission lines and the broad dip are occulted less than the continuum,
indicating vertical extension in these components. The dip is consistent with
the presence of a vertical ``Fe II'' absorbing curtain in the system. Archival
UV-optical spectra of the lower-inclination NL UX UMa show a bluer continuum
and weaker line emission than in V348 Pup and no broad dip. There is strong
flickering in V348 Pup. The flickering spectrum shows that the flickering
occurs only in the continuum. We did not detect any periodicities associated
with the rapid variability. The properties of V348 Pup are consistent with its
previous identification as a member of the SW Sex sub-class of NLs.


title: Molecular Line Observations of the Tornado Nebula and its Eye

abstract:
  We present millimetre and NIR molecular-line observations of the Tornado
nebula and its Eye. The observations were motivated by the presence of OH(1720
MHz) maser emission towards the nebula, believed to be an indicator of
interaction between a supernova remnant and a molecular cloud. We found that
the distribution of molecular gas around the Tornado complements its radio
morphology, implying that the nebula's appearance has been influenced by the
structure of the surrounding molecular gas. Our NIR H$_2$ observations revealed
the presence of shocked molecular gas at the location where the nebula is
expanding into the surrounding molecular cloud.
  It has been suggested that the Eye of the Tornado is related to the nebula on
the basis of their apparent proximity. Our NIR and millimetre-line observations
show that the two objects are not spatially related. Br $\gamma$ line emission,
in conjuction with IR data at longer wavelengths and high-resolution radio
continuum observations, suggests that the Eye is a massive protostellar source
deeply embedded within a dense molecular core.


title: Radiative Transfer on Perturbations in Protoplanetary Disks

abstract:
  We present a method for calculating the radiative tranfer on a protoplanetary
disk perturbed by a protoplanet. We apply this method to determine the effect
on the temperature structure within the photosphere of a passive circumstellar
disk in the vicinity of a small protoplanet of up to 20 Earth masses. The
gravitational potential of a protoplanet induces a compression of the disk
material near it, resulting in a decrement in the density at the disk's
surface. Thus, an isodensity contour at the height of the photosphere takes on
the shape of a well. When such a well is illuminated by stellar irradiation at
grazing incidence, it results in cooling in a shadowed region and heating in an
exposed region. For typical stellar and disk parameters relevant to the epoch
of planet formation, we find that the temperature variation due to a
protoplanet at 1 AU separation from its parent star is about 4% (5 K) for a
planet of 1 Earth mass, about 14% (19 K) for planet of 10 Earth masses, and
about 18% (25 K) for planet of 20 Earth masses, We conclude that even such
relatively small protoplanets can induce temperature variations in a passive
disk. Therefore, many of the processes involved in planet formation should not
be modeled with a locally isothermal equation of state.


title: A New Model of Solar Neutrinos in Manifest Violation of CPT Invariance

abstract:
  The large mixing (mass)(LMA)-MSW model of solar neutrinos (nue) is now widely
held to be near definitive, based on global consistency with data. No physical
effect, however, compels its uniqueness. The present search for an explicitly
testable competitive model was stimulated by a surprising finding--the high
energy part of the standard solar model (SSM) 8B nue spectrum can be scaled
very precisely to observed flux levels without measurable shape distortion via
sensitive combinations of long wavelength flavor conversion in vacuum and a 8B
flux f(B)<f(B:SSM).Pursuantly, a new "astroparticle" model with the relatively
specific parameters deltam2 = 76-78 mueV2 (10-12 eV2); sin2 2theta = 0.59-0.55;
f(B) =0.8f(B:SSM) coupled with modest changes in the SSM, offers a viable
solution consistent with data. Because KamLAND has set deltam2~50x106 mueV2,
sin2 2theta~1 for antineutrinos, our model manifestly violates CPT invariance.
The model predicts new distortional effects in solar neutrino spectra via nu-e
scattering signals in the window 3-5MeV, even though the spectrum is flat above
5 MeV. in This window that is accessible to experiment for the first time in
KamLAND. New experiments are proposed to observe the more dramatic
charged-current spectral effects.


title:
Atomic Calculations and Spectral Models of X-ray Absorption and Emission
  Features From Astrophysical Photoionized Plasmas

abstract:
  We present a detailed model of the discrete X-ray spectroscopic features
expected from steady-state, low-density photoionized plasmas. We apply the
Flexible Atomic Code (FAC) to calculate all of the necessary atomic data for
the full range of ions relevant for the X-ray regime. These calculations have
been incorporated into a simple model of a cone of ions irradiated by a point
source located at its tip (now available as the XSPEC model PHOTOION). For each
ionic species in the cone, photoionization is balanced by recombination and
ensuing radiative cascades, and photoexcitation of resonance transitions is
balanced by radiative decay. This simple model is useful for diagnosing X-ray
emission mechanisms, determining photoionization/photoexcitation/recombination
rates, fitting temperatures and ionic emission measures, and probing
geometrical properties (covering factor/column densities/radial filling
factor/velocity distributions) of absorbing/reemitting regions in photoionized
plasmas. Such plasmas have already been observed in diverse astrophysical X-ray
sources, including active galactic nuclei, X-ray binaries, cataclysmic
variables, and stellar winds of early-type stars, and may also provide a
significant contribution to the X-ray spectra of gamma-ray-burst afterglows and
the intergalactic medium.


title:
The Ages and Abundances of a Sample of Globular Clusters in M49 (NGC
  4472)

abstract:
  We present a study of the metallicity and age of the globular clusters system
of M49 (NGC 4472), the most luminous galaxy in the Virgo cluster. We measure
Lick indices for 47 GCs in M49 from LRIS/Keck spectra and establish their
metallicity parameters qualitatively in comparison to the Galactic GCs and to
published data for 150 M87 GCs. We then compare our measurements with the
predictions of models for the integrated light of old single burst stellar
systems by Worthey and by Thomas, Maraston & Bender. We find that the
metallicity of the M49 GC system spans the range from [Fe/H]_Z = -2.0 to +0.4
dex. We show that the metallicity and age parameters for these two GC systems
are basically identical, except that the M49 GCs reach slightly higher
metallicities than do those of M87. We find that the GCs of both of these giant
elliptical galaxies are alpha-enhanced by a factor of about two above the Solar
value, as is also true of the Galactic GCs. While adoption of the
alpha-enhanced models of TMB has eliminated most of the previous discrepancies
with observations, the most metal rich M49 GCs have NaD lines which are still
considerably stronger than those predicted by any model, and there are still
issues involving the metallicity scale of these models. We find that in the
mean, the M49 GCs are at least 10 Gyr old. However, the grids of models we used
differ in how they treat the horizontal branch, and this perceptibly affects
the predicted Hbeta index. Hence our current incomplete understanding of the
role of the horizontal branch limits our ability to derive a more detailed
distribution for the ages of the GCs in M49 and in M87.


title:
Automatic Detection of Expanding HI Shells Using Artificial Neural
  Networks

abstract:
  The identification of expanding HI shells is difficult because of their
variable morphological characteristics. The detection of HI bubbles on a global
scale therefore never has been attempted. In this paper, an automatic detector
for expanding HI shells is presented. The detection is based on the more stable
dynamical characteristics of expanding shells and is performed in two stages.
The first one is the recognition of the dynamical signature of an expanding
bubble in the velocity spectra, based on the classification of an artificial
neural network. The pixels associated with these recognized spectra are
identified on each velocity channel. The second stage consists in looking for
concentrations of those pixels that were firstly pointed out, and to decide if
they are potential detections by morphological and 21-cm emission variation
considerations. Two test bubbles are correctly detected and a potentially new
case of shell that is visually very convincing is discovered. About 0.6% of the
surveyed pixels are identified as part of a bubble. These may be false
detections, but still constitute regions of space with high probability of
finding an expanding shell. The subsequent search field is thus significantly
reduced. We intend to conduct in the near future a large scale HI shells
detection over the Perseus Arm using our detector.


title:
VLBI Imaging of Luminous Infrared Galaxies: AGN Cores in Mrk231, UGC
  5101 & NGC 7469

abstract:
  We report 18cm VLBI continuum imaging observations at 5 mas resolution for
UGC 5101, NGC 7469, and Mrk 231, all part of a sample of Luminous Infrared
Galaxies which have been shown to have strong VLBI radio cores. The radio
morphology of these three systems on VLBI scales is AGN-like, with well-defined
ridgelines and high-brightness yet spatially resolved components. The structure
and flux densities of these VLBI components are not consistent with starburst
generated radio supernovae of the type found in Arp 220. On scales of 100pc the
radio continuum in all three objects appears to be dominated by an AGN, not a
starburst. Radio emission on larger scales may well originate in a less compact
circumnuclear star-forming region.
  Confirming and extending VLBI imaging of Mrk 231 by Ulvestad et al. (1999),
our continuum image shows a triple structure, with a core and two lobes,
classifying it as a Compact Symmetric Object (CS0). If the southern (primary)
lobe/hot-spot in Mrk 231 is confined by ram pressure, we estimate a lobe
advance speed, $v_a \sim 10^{-4}c$, and an age for the jet/compact source, $<
10^6 yr$. We have also imaged the 1667 MHz OH maser emission in Mrk 231, which
is extended on scales of 50--100 milliarcsec (40--80 pc) and probably coincides
with the inner region of the disk which is seen in CO emission and HI
absorption. Among OH megamasers studied at high sensitivity with mas
resolution, Mrk 231 is unique in the stringent upper limits placed upon the
flux density of compact OH structures of the type found in Arp 220 and other
LIGs. It is possible that the circumnuclear environment of Mrk 231 has been
sufficiently disrupted by the emergent QSO that the cool, dense clouds
necessary for such compact masers no longer exist.


title: The Status of Very High Energy Astronomy

abstract:
  This paper summarizes the status of very high-energy (VHE) astronomy, as of
early 2003. It concentrates on observations made by gamma-ray telescopes
operating at energies above 10 GeV. This field is an exciting one to be working
in, with a growing and varied list of established sources that includes
plerions, supernova remnants, and active galactic nuclei. New results include
the discovery of the first unidentified source at these energies and the
detection of gamma rays from a nearby starburst galaxy (NGC 253). The arrival
of a new generation of telescopes, both on the ground and in space, argues that
we can anticipate a wealth of exciting results in the near future.


title:
Non-LTE Analysis for the Sodium Abundances of Metal-Poor Stars in the
  Galactic Disk and Halo

abstract:
  We performed an extensive non-LTE analysis of the neutral sodium lines of Na
{\sc i} 5683/5688, 5890/5896, 6154/6161, and 8183/8195 for disk/halo stars of
F--K type covering a wide metallicity range ($-4 \la$ [Fe/H] $\la 0.4$), based
on our own data as well as those collected from the literature. For
comparatively metal-rich disk stars ($-1 \la$ [Fe/H] $\la 0$) where the weaker
6154/6161 lines are best abundance indicators, we confirmed [Na/Fe] $\sim$ 0
with an ``upturn'' (i.e., a shallow/broad dip around $-0.5 \la$ [Fe/H] $\la 0$)
as already reported by previous studies. Regarding the metal-deficient halo
stars, where the much stronger 5890/5896 or 8183/8195 lines suffering
considerable (negative) non-LTE corrections amounting to 0.5 dex have to be
used, our analysis suggests mildly ``subsolar'' [Na/Fe] values down to $\sim
-0.4$ (with a somewhat large scatter of $\sim \pm 0.2$ dex) on the average at
the typical halo metallicity of [Fe/H] $\sim -2$, while they appear to rise
again toward a very metal-poor regime recovering a near-solar ratio of [Na/Fe]
$\sim$ 0 ([Fe/H] $\sim -3$ to -4). These results are discussed in comparison
with the previous observational studies along with the theoretical predictions
from the available chemical evolution models.


title:
Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: I.
  The HI Disk

abstract:
  We derived the three-dimensional distribution of HI gas in the Milky Way
Galaxy using the latest HI survey data cubes and rotation curves. The distance
of the HI gas was determined by the kinematic distance using a rotation curve.
We solved the near-far problem in the inner Galaxy by a fitting method which
involves introducing a model of vertical HI distribution.
  In our resultant maps we could trace three prominent arms: the
Sagittarius-Carina arm, the Perseus arm, and the Outer arm. These three arms
were found to be logarithmic spiral arms. The pitch angles of the
Sagittarius-Carina, Perseus, and Outer arms were estimated to be about
$11\arcdeg$, $18\arcdeg$, and $7\arcdeg$, respectively. The Sun is located in a
region rich in HI gas between the Sagittarius-Carina arm and the Perseus arm.
  The HI disk shows large and asymmetric warping in the outer disk: the HI disk
goes up to about 1.5 kpc above the Galactic plane in the northern hemisphere,
and down to about 1 kpc in the southern hemisphere, which means asymmetric
warping. The inner HI disk is also found to be tilting. The radius of the HI
disk is about 17 kpc and the HI mass within this radius is estimated to be $2.5
\times 10^9$ M$_\odot$, which corresponds to 1.5 % of the dynamical mass
predicted from the rotation curve. We also found that the HI outskirt is
largely swelling in the fourth quadrant, and hence the Galaxy is significantly
lopsided. The scale-height of the HI layer increases with the radius, and is
correlated with the HI volume density at the centroid of the HI layer.


title: Infrared Parallaxes for Methane T dwarfs

abstract:
  We report final results from our 2.5 year infrared parallax program carried
out with the European Southern Observatory 3.5m New Technology Telescope and
the SOFI infrared camera. Our program targeted precision astrometric
observations of ten T type brown dwarfs in the J band. Full astrometric
solutions (including trigonometric parallaxes) for nine T dwarfs are provided
along with proper motion solutions for a further object. We find that
HgCdTe-based infrared cameras are capable of delivering precision differential
astrometry. For T dwarfs, infrared observations are to be greatly preferred
over the optical, both because they are so much brighter in the infrared, and
because their prominent methane absorptions lead to similar effective
wavelengths through the J-filter for both target and reference stars, which in
turn results in a dramatic reduction in differential colour refraction effects.
We describe a technique for robust bias estimation and linearity correction
with the SOFI camera, along with an upper limit to the astrometric distortion
of the SOFI optical train. Colour-magnitude and spectral-type-magnitude
diagrams for both L and T dwarfs are presented which show complex and
significant structure, with major import for luminosity function and mass
function work on T dwarfs. Based on the width of the early L dwarf and late T
dwarf colour magnitude diagrams, we conclude the brightening of early T dwarfs
in the J passband (the "early T hump") is not an age effect, but due to the
complexity of brown dwarf cooling curves. Finally, empirical estimates of the
"turn on" magnitudes for methane absorption in field T dwarfs and in young
stars clusters are provided. These make the interpretation of the T6 dwarf
sigma Ori J053810.1-023626 as a sigma Ori member problematic.


title: The promise of interferometry in the mm range: ALMA

abstract:
  The Atacama Large Millimeter Array (ALMA), a world-wide project
(64x12m-dishes operating from 84 to 720 GHz, to be completed by 2011) will
represent a jump of almost two orders of magnitude in sensitivity and angular
resolution as compared to present millimeter/submillimeter interferometers, and
will thus undoubtedly produce a major step in astrophysics. The main objectives
will be the origins of galaxies, stars and planets. ALMA will be able to detect
dust-enshrouded star-forming galaxies at redshifts z > 10, both in the emission
of dust and spectral lines (CO and other species, including C+). It will also
explore in detail the physical and chemical processes of star and planet
formation hidden away in dusty molecular clouds and protoplanetary disks. In
addition, ALMA will allow similar enormous gains in all other fields of mm and
submm astronomy, including nearby galaxies, AGN, astrochemistry, circumstellar
shells and the solar system.


title:
Signatures of Pulsar Polar-Cap Emission at the High-Energy Spectral
  Cut-off

abstract:
  We address four unique signatures in pulsar gamma-ray radiation as predicted
by polar-cap models. These signatures are expected to be present nearby the
spectral high-energy cutoff at around several GeV. Their magnitude and,
therefore, their observability depends strongly on the orientational factors,
the rotation, as well as on the details of the polar cap structure. These
strong predictions are likely to be verified by the NASA's future gamma-ray
mission GLAST.


title: Cosmic Evolution Impressions on Lensing Maps

abstract:
  I investigate through simulations the redshift dependence of several lensing
measures for two cosmological models, a flat universe with a cosmological
constant (\LambdaCDM), and an open universe (OCDM). I argue that quintessence
models can be seen as an intermediate model between these two models under the
weak gravitational lensing perspective. I calculate for the convergence field
the angular power spectrum, the variance and higher order moments, the
probability distribution function, and the Minkowski functionals. I find that
in the redshift range examined (from z=0.7 to z=3 various statistics show an
increase of the non-Gaussianity of the lensing maps for closer sources. Lensing
surveys of higher redshift are expected to be less non-Gaussian than shallow
ones because of the non-linear evolution of the density field, and the central
limit theorem.


title:
Long-term X-ray variability of the microquasar system LS 5039/RX
  J1826.2-1450

abstract:
  We report on the results of the spectral and timing analysis of a BeppoSAX
observation of the microquasar system LS 5039/RX J1826.2-1450. The source was
found in a low-flux state with Fx(1-10 keV)= 4.7 x 10^{-12} erg cm^{-2} s^{-1},
which represents almost one order of magnitude lower than a previous RXTE
observation 2.5 years before. The 0.1--10 keV spectrum is described by an
absorbed power-law continuum with photon-number spectral index Gamma=1.8+-0.2
and hydrogen column density of NH=1.0^{+0.4}_{-0.3} x 10^{22} cm^{-2}.
According to the orbital parameters of the system the BeppoSAX observation
covers the time of an X-ray eclipse should one occur. However, the 1.6-10 keV
light curve does not show evidence for such an event, which allows us to give
an upper limit to the inclination of the system. The low X-ray flux detected
during this observation is interpreted as a decrease in the mass accretion rate
onto the compact object due to a decrease in the mass-loss rate from the
primary.


title:
Mid-Infrared observations of GRS 1915+105 during plateau and flaring
  states

abstract:
  We present mid-infrared (4-18 micron) observations of the microquasar GRS
1915+105 obtained with ISOCAM, the camera on board the Infrared Space
Observatory (ISO), in 1996 April and 1997 October. The first observation
probably occurred during a flaring event with oscillating synchrotron emission.
The 1997 observation occurred a few days before a major relativistic ejection,
during a plateau state of inverted-spectrum radio emission and hard
quasi-stable X-ray emission. The K-M giant donor star in GRS 1915+105 cannot
account for the mid-IR emission and we discuss the possible additional
components depending on two absorption laws. Thermal emission from dust seems
unlikely. The flat mid-IR spectrum obtained during the plateau state is likely
to be synchrotron emission. It would be the first evidence of the infrared
extension of the radio synchrotron emission from the compact jets, although
optically thin free-free emission from an X-ray driven-wind from the accretion
disc cannot be excluded.


title: Millisecond oscillators in accreting neutron stars and black holes

abstract:
  Millisecond variability detected in low-mass X-ray binaries (LMXBs) probably
reflects motions of accreting fluid in the strong-field gravity of neutron
stars or neutron stars. Parametric resonance between two oscillators with
unequal eigenfrequencies provides a natural explanation for the 2:3 frequency
ratio observed in some black-hole systems, and probably also in the brightest
neutron stars. The two oscillators likely correspond to the meridional and
radial epicyclic motions.


title:
Radio Afterglows of Gamma-Ray Bursts: Unique Clues to the Energetics and
  Environments

abstract:
  Radio observations of gamma-ray burst (GRB) afterglows provide both
complementary and unique diagnostics of the afterglow physics and environment
of the burst. Here we concentrate on three unique aspects of GRB energetics and
environments afforded by radio and submillimeter observations: the
non-relativistic evolution of the fireball, the density profile of the
circumburst medium, and the study of obscured star formation in GRB host
galaxies.


title: Fast X-ray Transients and Their Connection to Gamma-Ray Bursts

abstract:
  Fast X-ray transients (FXTs) with timescales from seconds to hours have been
seen by numerous space instruments. We have assembled archival data from
Ariel-5, HEAO-1 (A-1 and A-2), WATCH, ROSAT, and Einstein to produce a global
fluence-frequency relationship for these events. Fitting the log N-log S
distribution over several orders of magnitude to simple power law we find a
slope of -1.0. The sources of FXTs are undoubtedly heterogeneous, the -1 power
law is an approximate result of the summation of these multiple sources. Two
major contributions come from gamma-ray bursts and stellar flares.
Extrapolating from the BATSE catalog of GRBs, we find that the fraction of
X-ray flashes that can be the X-ray counterparts of gamma-ray bursts is a
function of fluence. Certainly most FXTs are not counterparts of standard
gamma-ray bursts. The fraction of FXTs from non-GRB sources, such as magnetic
stars, is greatest for the faintest FXTs. Our understanding of the FXT
phenomenon remains limited and would greatly benefit from a large, homogeneous
data set, which requires a wide-field, sensitive instrument.


title:
Local Radiative Hydrodynamic and Magnetohydrodynamic Instabilities in
  Optically Thick Media

abstract:
  We examine the local conditions for radiative damping and driving of short
wavelength, propagating hydrodynamic and magnetohydrodynamic (MHD) waves in
static, optically thick, stratified equilibria. We show that so-called strange
modes in stellar oscillation theory and magnetic photon bubbles are intimately
related and are both fundamentally driven by the background radiation flux
acting on compressible waves. We identify the necessary criteria for unstable
driving of these waves, and show that this driving can exist in both gas and
radiation pressure dominated media, as well as pure Thomson scattering media in
the MHD case. The equilibrium flux acting on opacity fluctuations can drive
both hydrodynamic acoustic waves and magnetosonic waves unstable. In addition,
magnetosonic waves can be driven unstable by a combination of the equilibrium
flux acting on density fluctuations and changes in the background radiation
pressure along fluid displacements. We briefly describe the conditions under
which these instabilities might be manifested in both main sequence stellar
envelopes and accretion disks.


title:
Spectral Irradiance Calibration in the Infrared. XIII. "Supertemplates"
  and On-Orbit Calibrators for SIRTF's Infrared Array Camera (IRAC)

abstract:
  We describe the technique used to develop on-orbit calibrators for IRAC and
validate the method for either K0-M0III or A0-A5V stars. For SIRTF, the
approach uses all available optical, NIR, and MIR photometry, and yields
absolute spectra from UV to MIR. One set of stars is from Landolt's network of
optical standards, the other from Carter-Meadows IR standards. Traceability to
the Cohen-Walker- Witteborn framework of absolute photometry and spectra is
assured. The method is based on using either "supertemplates" to represent the
intrinsic shapes of the spectra of K0-M0IIIs from 1150A to 35 um, or Kurucz
synthetic spectra for A0-5V stars. Each supertemplate/model is reddened
according to a star's extinction and normalized by characterized optical
photometry. This paper tests our ability to predict NIR (JHK) magnitudes from
supertemplates or models constrained by Hippa- rcos/Tycho or precision
ground-based optical data. We offer absolute calibrated spectra of 33 optical
standards to demonstrate the viability of this technique for a set of IR
calibrators 100-1000 times fainter than we have previously publ- ished. We
calculate the absolute uncertainties associated with predicting IRAC mags for
the faintest cool giant and hot dwarf in this new set of calibrators.


title:
Spectral Irradiance Calibration in the Infrared. XIV: the Absolute
  Calibration of 2MASS

abstract:
  Element-by-element we have combined the optical components in the three 2MASS
cameras, and incorporated detector quantum efficiency curves and site-specific
atmospheric transmissions, to create three relative spectral response curves
(RSRs). We provide absolute 2MASS attributes associated with "zero magnitude"
in the JHKs bands so that these RSRs may be used for synthetic photometry. The
RSRs tie 2MASS to the Cohen-Walker-Witteborn framework of absolute photometry
and spectra for the purpose of using 2MASS data to support the development of
absolute calibrators for IRAC and pairwise cross-calibrators between all three
SIRTF instruments. We examine the robustness of these RSRs to changes in water
vapor within a night. We compare the observed 2MASS magnitudes of 33 stars
(converted from the precision optical calibrators of Landolt and Carter-Meadows
into absolute infrared calibrators from 1.2-35 um with our predictions, thereby
deriving 2MASS "zero point offsets" from the ensemble. These offsets are the
final ingredients essential to merge 2MASS $JHK_{s}$ data with other absolutely
calibrated bands and stellar spectra, and to support the creation of faint
calibration stars for SIRTF.


title:
Distribution of the Galactic Bulge emission at |b|>2deg according to the
  RXTE Galactic Center scans

abstract:
  We present an analysis of the Galactic bulge emission observed by the
RXTE/PCA during a set of scans over the Galactic Center field, performed in
1999-2001. The total exposure time of these observations is close to 700 ksec.
We construct the distribution of Galactic ridge emission intensity and spectral
parameters up to Galactic latitudes b=-10deg;+9deg. We show that the intensity
distribution of the ridge emission at |b|>2deg could be well described by an
exponential model with e-folding width b_0~ 3.3deg. Best-fit spectral
parameters do not show statistically significant changes over Galactic latitude


title: New Resources to Explore the Old Galaxy: Mining the SDSS

abstract:
  The Sloan Digital Sky Survey (SDSS) is collecting photometry and intermediate
resolution spectra for ~ 10**5 stars in the thick-disk and stellar halo of the
Milky Way. This massive dataset can be used to infer the properties of the
stars that make up these structures, and considerably deepen our vision of the
old components of the Galaxy. We devise tools for automatic analysis of the
SDSS photometric and spectroscopic data based on plane-parallel line-blanketed
LTE model atmospheres and fast optimization algorithms. A preliminary study of
about 5000 stars in the Early Data Release gives a hint of the vast amount of
information that the SDSS stellar sample contains.


title:
RXTE observations of strongly absorbed sources IGR J16318-4848 and IGR
  J16358-4726

abstract:
  Results of analysis of RXTE observations of strongly absorbed X-ray sources
IGR J16318-4848 and IGR J16358-4726 are presented. Careful subtraction of
Galactic ridge emission contribution to the observed spectra of RXTE/PCA
allowed us to obtain the spectra of the sources in 3-25 keV energy band.
Spectra of the sources cold be well described by a power law with
photoabsorption. It is shown that the value of absorption column in the case of
RXTE observation of IGR J16318-4848 performed on March 14.1, 2003 is somewhat
higher that that obtained by XMM observatory on Feb 10.7 2003. This could imply
that the source has variable absorption, presumably connected with an orbital
phase of the binary system. It is noted, that all three X-ray sources,
discovered by INTEGRAL observatory in the sky region of (l,b)~(336,0) (IGR
J16318-4848, IGR J16320-4751 and IGR J16358-4726) have large intrinsic
photoabsorption and could be high mass X-ray binaries. This hypothesis has
indirect support from the fact that their are located close to the Norma spiral
arm tangent, i.e. in the region of enhanced concentrations of young massive
stars. If they are reside within this spiral arm some rough estimation of the
sources distance could be made -- D~6-8 kpc.


title:
The generality of inflation in closed cosmological models with some
  quintessence potentials

abstract:
  We have investigated the generality of inflation (the probability of
inflation in other words) in closed FRW models for a wide class of quintessence
potentials. It is shown that inflation is not suppressed for most of them and
for a wide enough range of their parameters. It allows us to decide inflation
is common enough even in the case of closed Universe.


title:
Substructure in dark matter halos: Towards a model of the abundance and
  spatial distribution of subclumps

abstract:
  I develop a model for the abundance and spatial distribution of dark matter
subclumps. The model shows that subclumps of massive parent halos formed at
earlier times than subclumps of the same mass in lower mass parents;
equivalently, halos in dense regions at a given time formed earlier than halos
of the same mass in less dense regions. This may provide the basis for
interpreting recent observations which indicate that the stellar populations of
the most massive elliptical galaxies are also the oldest.


title: Search for TeV gamma-rays from SN 1987A in 2001

abstract:
  We searched for TeV gamma-rays from the remnant of SN 1987A around 5400 days
after the supernova. The observations were carried out in 2001, from November
16 to December 11, using the CANGAROO-II Imaging Atmospheric Cherenkov
Telescope. In total, 708 minutes of ON- and 1019 minutes of OFF-source data
were obtained under good conditions. The detection threshold was estimated to
be 1 TeV, due to the mean zenith angle of 39$^\circ$. The upper limits for the
gamma-ray flux were obtained and compared with the previous observations and
theoretical models. The observations indicate that the gamma-ray luminosity is
lower than $1\times 10^{37}$ erg s$^{-1}$ at $\sim 10$ TeV.


title:
Rapid Variations of Narrow Absorption Line Components in the Spectrum of
  P Cygni

abstract:
  We report the detection of rapid wavelength and intensity variations of
narrow components in absorption line profiles of the hot galactic supergiant P
Cygni. During most of the time, in one week of observations, there were two
such components present. Although the period of observation is too short for
firm conclusions, the velocity curves do not contradict the photometic period
of 17.3 d. These curves may be interpreted as a double wave, 'swinging in
counterphase'. This observation would suggest the presence of one long wave
over the stellar surface. The waves are possibly gravity waves with wavelengths
of the order of half the stellar radius.


title:
New measurement of the Lithium-6/Lithium-7 isotopic ratio in the
  extra-solar planet host star HD82943 and line blending in the Li 6708 A
  region

abstract:
  The presence of possible blends in the spectral region of the Li resonance
line at 6708 A in solar-type metal-rich stars is investigated using high
resolution and high signal-to-noise spectroscopic observations. Our analysis
does not confirm the identification of a weak absorption feature at 6708.025 A
with the low excitation TiI line proposed by Reddy et al. (2002). Our spectrum
synthesis suggests that the unidentified absorption is most probably produced
by a high excitation SiI line originally proposed by Muller et al. (1975).
Reanalysis of the Lithium-6/Lithium-7 isotopic ratio in HD82943 was performed
by taking the SiI line into account and using new VLT/UVES spectra of HD82943
with a signal-to-noise ratio close to 1000. We confirm the presence of
Lithium-6 in the star's atmosphere while the updated value for the isotopic
ratio is f(Lithium-6) = 0.05+-0.02.