title:
Measuring Cosmological Parameters with the SDSS QSO Spatial Power
  Spectrum Analysis to Test the Cosmological Principle

abstract:
  In this paper we emphasize the importance of the Sloan Digital Sky Survey
(SDSS) QSO clustering statistics as a unique probe of the Universe. Because the
complete SDSS QSO sample covers a quarter of the observable universe,
cosmological parameters estimated from the clustering statistics have an
implication as a test of the cosmological principle, by comparing with those
from local galaxies and other cosmological observations. Using an analytic
approach to the power spectrum for the QSO sample, we assess the accuracy with
which the cosmological parameters can be determined. Arguments based on the
Fisher matrix approach demonstrate that the SDSS QSO sample might have a
potential to provide useful constraints on the density parameters as well as
the cosmic equation of state.


title: On the oxygen abundance in our Galaxy

abstract:
  The compilation of published spectra of Galactic HII regions with available
diagnostic [OIII]4363 line has been carried out. Our list contains 71
individual measurements of 13 HII regions in the range of galactocentric
distances from 6.6 to 14.8 kpc. The oxygen abundances in all the HII regions
were recomputed in the same way, using the classic Te - method. The oxygen
abundance at the solar galactocentric distance traced by those HII regions is
in agreement with the oxygen abundance in the interstellar medium in the solar
vicinity derived with high precision from the interstellar absorption lines
towards stars. The derived radial oxygen abundance distribution was compared
with that for HII regions from the Shaver et al. (1983) sample which is the
basis of many models for the chemical evolution of our Galaxy. It was found
that the original Shaver et al.'s oxygen abundances are overestimated by
0.2-0.3 dex. Oxygen abundances in HII regions from the Shaver et al. sample
have been redetermined with the recently suggested P - method. The radial
distribution of oxygen abundances from the Shaver et al. sample redetermined
with the P - method is in agreement with our radial distribution of (O/H)_Te
abundances.


title:
Constraining the third dredge-up via carbon stars in the Magellanic
  Clouds

abstract:
  We use the available data for Magellanic Cloud carbon stars to constrain the
efficiency of the third dredge-up process in TP-AGB models. We show that star
counts in LMC clusters provide quite stringent limits to the lifetime of the
C-star phase, with a duration between 2 and 3 Myr for stars in the mass range
from 1.5 to 2.8 Msun. Together with the luminosity functions of field C stars,
this information allows us to re-calibrate the third dredge-up parameters log
T_b_dred and lambda in TP-AGB models that include variable molecular opacities
(Marigo 2002). Preliminary results are presented here.


title: Realistic error estimates on kinematic parameters

abstract:
  Current error estimates on kinematic parameters are based on the assumption
that the data points in the spectra follow a Poisson distribution. For
realistic data that have undergone several steps in a reduction process, this
is generally not the case. Neither is the noise distribution independent in
adjacent pixels. Hence, the error estimates on the derived kinematic parameters
will (in most cases) be smaller than the real errors. In this paper we propose
a method that makes a diagnosis of the characteristics of the observed noise
The method also offers the possibility to calculate more realistic error
estimates on kinematic parameters. The method was tested on spectroscopic
observations of NGC3258. In this particular case, the realistic errors are
almost a factor of 2 larger than the errors based on least squares statistics.


title: Multiwavelength observations of the GRB000615 field

abstract:
  We report on prompt and afterglow observations of GRB 000615 detected by
BeppoSAX. The study of the high-energy prompt event is presented along with the
search for its X-ray and optical afterglow. Spectral fits seem to suggest a
temporal evolution of the GRB prompt emission. We possibly find evidence for
intrinsic N_H (at 90% confidence level) and for a transient spectral emission
feature around 8 keV (at 98% confidence level). The X-ray to gamma-ray fluence
ratio of 1.73 +/- 0.22 is one of the largest among BeppoSAX GRBs. A weak X-ray
source is also detected in the MECS, between 1.6 and 4.5 keV, and its position
is compatible with the WFC error box. The behaviour of this source may be
compatible with that of an afterglow. Low significance signal is detected in
the 0.2-1.5 keV at a position consistent with the WFC and MECS error boxes. The
S/N ratio is insufficient to speculate on the nature of this source. There is
no evidence of an optical transient down to R ~ 22.


title:
On the carriers of the celestial infrared vibrational bands and their
  excitation mechanisms

abstract:
  The recent influx of high-quality infrared spectroscopic data has prompted an
extensive reassessment of various laboratory models in comparison with the
observed UIBs (Unidentified Infrared Bands). As a result, significant
modifications were brought to the original paradigms. The focus here is on the
correction of the coal model, characterized by: 1) a shift towards less
aromatic materials of the same family (kerogens; the composition, structure and
IR spectrum of these materials are extensively documented in the geology
literature); 2) the introduction of a new excitation mechanism
(chemiluminescence), based on the capture of hydrogen atoms by carbonaceous
dust. The fundamental characters of this model, viz. chemical and structural
disorder, and diversity of chemical bondings, naturally point to ways of
further tailoring, in order to fit particular observations more closely.


title: Towards a free-free template for CMB foregrounds

abstract:
  A full-sky template map of the Galactic free-free foreground emission
component is increasingly important for high sensitivity CMB experiments. We
use the recently published \ha data of both the northern and southern skies as
the basis for such a template.
  The first step is to correct the \ha maps for dust absorption using the 100
$\mu$m dust maps of Schlegel, Finkbeiner & Davis (1998). We show that for a
range of longitudes, the Galactic latitude distribution of absorption suggests
that it is 33 per cent of the full extragalactic absorption. A reliable
absorption-corrected \ha map can be produced for $\sim 95$ per cent of the sky;
the area for which a template cannot be recovered is the Galactic plane area
$|b| < 5^{\circ}$, $l=260^{\circ}-0^{\circ}-160^{\circ}$ and some isolated
dense dust clouds at intermediate latitudes.
  The second step is to convert the dust-corrected \ha data into a predicted
radio surface brightness. The free-free emission formula is revised to give an
accurate expression (1 per cent) for the radio emission covering the frequency
range 100 MHz to 100 GHz and the electron temperature range 3000 to 20000 K.
The main uncertainty when applying this expression is the variation of electron
temperature across the sky. The emission formula is verified in several
extended H{\sc ii} regions using data in the range 408 to 2326 MHz.
  A full-sky free-free template map is presented at 30 GHz; the scaling to
other frequencies is given. The Haslam et al. all-sky 408 MHz map of the sky
can be corrected for this free-free component, which amounts to a $\approx 6$
per cent correction at intermediate and high latitudes....


title: The angular size - redshift relation in power-law cosmologies

abstract:
  A linear evolution of the cosmological scale factor is a feature in several
models designed to solve the cosmological constant problem via a coupling
between scalar or tensor classical fields to the space-time curvature as well
as in some alternative gravity theories. In this paper, by assuming a general
time dependence of the scale factor, $R \sim t^{\alpha}$, we investigate
observational constraints on the dimensionless parameter $\alpha$ from
measurements of the angular size for a large sample of milliarcsecond compact
radio sources. In particular, we find that a strictly linear evolution, i.e.,
$\alpha \simeq 1$ is favoured by these data, which is also in agreement with
limits obtained from other independent cosmological tests. The dependence of
the critical redshift $z_m$ (at which a given angular size takes its minimal
value) with the index $\alpha$ is briefly discussed.


title: Possible detection of a magnetic field in T Tauri

abstract:
  Medium-resolution $(R\simeq 15000)$ circular spectropolarimetry of T Tauri is
presented. The star was observed twice: on November 11, 1996 and January 22,
2002. Weak circular polarization has been found in photospheric absorption
lines, indicating a mean surface longitudinal magnetic field $B_{\|}$ of
$160\pm 40$ G and $140\pm 50$ G at the epoch of the first and second
observations respectively. While these values are near the detection limit of
our apparatus, we belive that they are real. In any case one can conclude from
our data that $B_{\|}$ of T Tau does not significantly exceed 200 G, which is
much less than surface magnetic field strength of the star ($>2.3$ kG) found by
Guenther et al. (1999) and Johns-Krull et al. (2000). We discuss possible
reasons of this difference.


title: Thermal and Non-thermal Plasmas in the Galaxy Cluster 3C 129

abstract:
  We describe new Chandra spectroscopy data of the cluster which harbors the
prototypical "head tail" radio galaxy 3C 129 and the weaker radio galaxy 3C
129.1. We combined the Chandra data with Very Large Array (VLA) radio data
taken at 0.33, 5, and 8 GHz (archival data) and 1.4 GHz (new data). We also
obtained new HI observations at the Dominion Radio Astrophysical Observatory
(DRAO) to measure the neutral Hydrogen column density in the direction of the
cluster with arcminute angular resolution. The Chandra observation reveals
extended X-ray emission from the radio galaxy 3C 129.1 with a total luminosity
of 1.5E+41 erg/s. The X-ray excess is resolved into an extended central source
of ~2 arcsec (1 kpc) diameter and several point sources with an individual
luminosity up to 2.1E+40 erg/s. In the case of the radio galaxy 3C 129, the
Chandra observation shows, in addition to core and jet X-ray emission reported
in an earlier paper, some evidence for extended, diffuse X-ray emission from a
region east of the radio core. The 12 arcsec x 36 arcsec (6 kpc x 17 kpc)
region lies "in front" of the radio core, in the same direction into which the
radio galaxy is moving. We use the radio and X-ray data to study in detail the
pressure balance between the non-thermal radio plasma and the thermal Intra
Cluster Medium (ICM) along the tail of 3C 129 which extends over 15 arcmin (427
kpc). Depending on the assumed lower energy cutoff of the electron energy
spectrum, the minimum pressure of the radio plasma lies a factor of between 10
and 40 below the ICM pressure for a large part of the tail. We discuss several
possibilities to explain the apparent pressure mismatch.


title: Optical and NIR monitoring of the GRB020405 afterglow

abstract:
  Optical and near-infrared (NIR) observations of GRB020405 started about 1 day
after the GRB and extended over ~70 days. Photometry shows that the early decay
is consistent with a single power law of index alpha = 1.54 +- 0.06 in all
bands. The late epoch light curves, sampled with HST and VLT, exhibit a plateau
or slight rebrightening around 10-20 days after the GRB. This bump can be
modeled with a SN2002ap template underlying the afterglow. Alternatively, the
late-epoch data can also be fitted using a power law with index steeper (alpha'
= 1.85 +- 0.15) than that of the early decay phase, in agreement with a late
shell collision interpretation. Spectroscopy indicates that the GRB is at z =
0.691 and that the host galaxy complex is angularly close to a system of at
least two galaxies at z = 0.472. R-band polarimetry shows that the afterglow is
polarized, with $ = 1.5 +- 0.4 % and polarization angle theta = 172 +- 8
degrees.


title: Companions of old brown dwarfs, and very low mass stars

abstract:
  Up to now, most planet search projects have concentrated on F to K stars. In
order to considerably widen the view, we have stated a survey for planets of
old, nearby brown dwarfs and very low mass stars. Using UVES, we have observed
26 brown dwarfs and very low mass stars. These objects are quite inactive and
are thus highly suitable for such a project. Two objects were found to be
spectroscopic binaries. Another object shows significant radial velocity
variations. From our measurements, we conclude that this object either has a
planetary-mass companion, or the variations are caused by surface features.
Within the errors of the measurements, the remaining objects are constant in
radial velocity. While it is impossible to strictly exclude an orbiting planet
from sparsely sampled RV data, we conclude that it is unlikely that these
objects are orbited by massive planets with periods of 40 days or less.


title: A Nonlocal Metric Formulation of MOND

abstract:
  We study a class of nonlocal, but causal, covariant and conserved field
equations for the metric. Although nonlocal, these equations do not seem to
possess extra graviton solutions in weak field perturbation theory. Indeed, the
equations reduce to those of general relativity when the Ricci scalar vanishes
throughout spacetime. When a static matter source is present we show how these
equations can be adjusted to reproduce Milgrom's Modified Newtonian Dynamics in
the weak field regime, while reducing to general relativity for strong fields.
We compute the angular deflection of light in the weak field regime and
demonstrate that it is the same as for general relativity, resulting in far too
little lensing if no dark matter is present. We also study the field equations
for a general Robertson-Walker geometry. An interesting feature of our
equations is that they become conformally invariant in the MOND limit.


title:
Detection of dark matter Skewness in the VIRMOS-DESCART survey:
  Implications for \Omega_0

abstract:
  Weak gravitational lensing provides a direct statistical measure of the dark
matter distribution. The variance is easiest to measure, which constrains the
degenerate product \sigma_8\Omega^0.6. The degeneracy is broken by measuring
the skewness arising from the fact that densities must remain positive, which
is not possible when the initially symmetric perturbations become non-linear.
Skewness measures the non-linear mass scale, which in combination with the
variance measures \Omega directly. We present the first detection of dark
matter skewness from the Virmos-Decart survey. We have measured the full three
point function, and its projections onto windowed skewness. We separate the
lensing mode and the B mode. The lensing skewness is detected for a compensated
Gaussian on scales of 5.37 arc minutes to be \kappa^3=1.06+/-0.06x10^-6. The
B-modes are consistent with zero at this scale. The variance for the same
window function is \kappa^2= 5.32+/-0.62+/-0.98x10^-5, resulting in
S_3=375^{+342}_{-124}. Comparing to N-body simulations, we find \Omega_0<0.5 at
90% confidence. The Canada-France-Hawaii-Telescope legacy survey and newer
simulations should be able to improve significantly on the constraint.


title:
Early stages of Nitrogen enrichment in galaxies: Clues from measurements
  in damped Lyman alpha systems

abstract:
  We present 4 new measurements of nitrogen abundances and one upper limit in
damped Lyman alpha absorbers (DLAs) obtained by means of high resolution (FWHM
\~ 7 km/s) UVES/VLT spectra. In addition to these measurements we have compiled
data from all DLAs with measurements of nitrogen and alpha-capture elements (O,
S or Si) available in the literature, including all HIRES/Keck and UVES/VLT
data for a total of 33 systems, i.e. the largest sample investigated so far. We
find that [N/alpha] ratios are distributed in two groups: 75% of the DLAs show
a mean value of [N/alpha] = -0.87 with a scatter of 0.16 dex, while the
remaining 25% shows ratios clustered at [N/alpha] = -1.45 with an even lower
dispersion of 0.05 dex. The high [N/alpha] plateau is consistent with the one
observed in metal-poor HII regions of blue compact dwarf (BCD) galaxies
([N/alpha] = -0.73 +/- 0.13), while the [N/alpha] ~ -1.5 values are the lowest
ever observed in any astrophysical site. These low [N/alpha] ratios are real
and not due to ionization effects. They provide a crucial evidence against the
primary production of N by massive stars as responsible for the plateau at
-0.9/-0.7 dex observed in DLAs and BCD galaxies. The transition between the
low-N ([N/alpha] ~ -1.5) and high-N ([N/alpha] ~ -0.9) DLAs occurs at a
nitrogen abundance of [N/H] ~ -2.8, suggesting that the separation may result
from some peculiarity of the nitrogen enrichment history. The [N/alpha] ~ -1.5
values and their low dispersion are consistent with a modest production of
primary N in massive stars; however, due to the limited sample, specially for
the low-N DLAs, we cannot exclude a primary origin in intermediate mass stars
as responsible for the low N abundances observed.


title:
A Large Scale Energy Source For Feeding ISM Turbulence in Spiral
  Galaxies

abstract:
  One of the important consequences of a newly discovered secular dynamical
evolution process of spiral galaxies (Zhang 1996,1998,1999) is that the
orbiting disk matter receives energy injection each time it crosses the spiral
density wave crest. This energy injection has been shown to be able to
quantitatively explain the observed age-velocity-dispersion relation of the
solar neighborhood stars. We demostrate in this paper that similar energy
injection into the interstellar medium could serve as the large-scale energy
source to continuously power the observed interstellar turbulence and to offset
its downward cascade tendency.


title: A Map of the Cosmic Microwave Background from the BEAST Experiment

abstract:
  We present the first sky maps from the BEAST (Background Emission Anisotropy
Scanning Telescope) experiment. BEAST consists of a 2.2 meter off axis
Gregorian telescope fed by a cryogenic millimeter wavelength focal plane
currently consisting of 6 Q band (40 GHz) and 2 Ka band (30 GHz) scalar feed
horns feeding cryogenic HEMT amplifiers. Data were collected from two
balloon-borne flights in 2000, followed by a lengthy ground observing campaign
from the 3.8 Km altitude University of California White Mountain Research
Station. This paper reports the initial results from the ground based
observations. The instrument produced an annular map covering the sky from
declinateion 33 to 42 degrees. The maps cover an area of 2470 square degrees
with an effective resolution of 23 arcminutes FWHM at 40 GHz and 30 arcminutes
at 30 GHz. The map RMS (smoothed to 30 arcminutes and excluding galactic
foregrounds) is 54 +-5 microK at 40 GHz. Comparison with the instrument noise
gives a cosmic signal RMS contribution of 28 +-3 microK. An estimate of the
actual CMB sky signal requires taking into account the l-space filter function
of our experiment and analysis techniques, carried out in a companion paper
(O'Dwyer et al. 2003). In addition to the robust detection of CMB anisotropies,
we find a strong correlation between small portions of our maps and features in
recent H$\alpha$ maps (Finkbeiner, 2003). In this work we describe the data set
and analysis techniques leading to the maps, including data selection,
filtering, pointing reconstruction, mapmaking algorithms and systematic
effects. A detailed description of the experiment appears in Childers et al.
(2003).


title:
Primordial Black Holes as Dark Matter: The Power Spectrum and
  Evaporation of Early Structures

abstract:
  We consider the possibility that massive primordial black holes are the
dominant form of dark matter. Black hole formation generates entropy
fluctuations that adds a Poisson noise to the matter power spectrum. We use
Lyman-alpha forest observations to constrain this Poisson term in matter power
spectrum, then we constrain the mass of black holes to be less than few times
10^4 solar mass. We also find that structures with less than ~ 10^3 primordial
black holes evaporate by now.


title: Tests for Substructure in Gravitational Lenses

abstract:
  The flux anomalies in four-image gravitational lenses can be interpreted as
evidence for the dark matter substructure predicted by cold dark matter (CDM)
halo models. In principle, these flux anomalies could arise from alternate
sources such as absorption, scattering or scintillation by the interstellar
medium (ISM) of the lens galaxy, problems in the ellipsoidal macro models used
to fit lens systems, or stellar microlensing. We apply several tests to the
data that appear to rule out these alternate explanations. First, the radio
flux anomalies show no significant dependence on wavelength, as would be
expected for almost any propagation effect in the ISM or microlensing by the
stars. Second, the flux anomaly distributions show the characteristic
demagnifications of the brightest saddle point relative to the other images
expected for low optical depth substructure, which cannot be mimicked by either
the ISM or problems in the macro models. Microlensing by stars also cannot
reproduce the suppression of the bright saddle points if the radio source sizes
are consistent with the Compton limit for their angular sizes. Third, while it
is possible to change the smooth lens models to fit the flux anomalies in some
systems, we can rule out the necessary changes in all systems where we have
additional lens constraints to check the models. Moreover, the parameters of
these models are inconsistent with our present observations and expectations
for the structure of galaxies. We conclude that low-mass halos remain the best
explanation of the phenomenon.


title: Local Interstellar Matter: The Apex Cloud

abstract:
  Several nearby individual low column density interstellar cloudlets have been
identified based on kinematical features evident in high-resolution CaII
observations near the Sun. One of these cloudlets, the ``Aquila-Ophiuchus''
cloud, is within 5 pc of the Sun and located in the solar apex direction. The
velocity vector of this Apex Cloud is reevaluated and components at this
velocity are found towards 17 stars with distances 1--60 pc, and located
primarily in the galactic center hemisphere. The Apex Cloud is the most likely
candidate for the ``next'' interstellar cloud to be encountered by the Sun.


title: Dark Energy, Expansion History of the Universe, and SNAP

abstract:
  This talk presents a pedagogical discussion of how precision
distance-redshift observations can map out the recent expansion history of the
universe, including the present acceleration and the transition to matter
dominated deceleration. The proposed Supernova/Acceleration Probe (SNAP) will
carry out observations determining the components and equations of state of the
energy density, providing insights into the cosmological model, the nature of
the accelerating dark energy, and potentially clues to fundamental high energy
physics theories and gravitation. This includes the ability to distinguish
between various dynamical scalar field models for the dark energy, as well as
higher dimension and alternate gravity theories. A new, advantageous
parametrization for the study of dark energy to high redshift is also
presented.


title: High-Mass Microblazars Associated with Variable Gamma-Ray Sources?

abstract:
  A model to explain variable gamma-ray sources with high-mass microblazars is
described. Inverse Compton interactions between the jet of a microquasar and
the UV-photon field of the stellar companion can produce high-energy
gamma-rays. The interaction with photons from the disk and the corona is also
taken into account. The long-term variability presented by some sources is
related to the precession of the jet, which is induced by the gravitational
effect of the companion upon the accretion disk. Observations of repeated soft
gamma-ray outbursts from Cyg X-1 can be consistently interpreted under this
model.


title: Are Compact High-Velocity Clouds Extragalactic Objects?

abstract:
  Compact high-velocity clouds (CHVCs) are the most distant of the HVCs in the
Local Group model and would have HI volume densities of order 0.0003/cm^3.
Clouds with these volume densities and the observed neutral hydrogen column
densities will be largely ionized, even if exposed only to the extragalactic
ionizing radiation field. Here we examine the implications of this process for
models of CHVCs. We have modeled the ionization structure of spherical clouds
(with and without dark matter halos) for a large range of densities and sizes,
appropriate to CHVCs over the range of suggested distances, exposed to the
extragalactic ionizing photon flux. Constant-density cloud models in which the
CHVCs are at Local Group distances have total (ionized plus neutral) gas masses
roughly 20-30 times larger than the neutral gas masses, implying that the gas
mass alone of the observed population of CHVCs is about 40 billion solar
masses. With a realistic (10:1) dark matter to gas mass ratio, the total mass
in such CHVCs is a significant fraction of the dynamical mass of the Local
Group, and their line widths would exceed the observed FWHM. Models with dark
matter halos fare even more poorly; they must lie within approximately 200 kpc
of the Galaxy. We show that exponential neutral hydrogen column density
profiles are a natural consequence of an external source of ionizing photons,
and argue that these profiles cannot be used to derive model-independent
distances to the CHVCs. These results argue strongly that the CHVCs are not
cosmological objects, and are instead associated with the Galactic halo.


title:
UV Continuum, Physical Conditions and Filling Factor in Active Galactic
  Nuclei

abstract:
  The narrow line region of active galaxies is formed by gas clouds surrounded
by a diluted gas. Standard one-dimensional photoionization models are usually
used to model this region in order to reproduce the observed emission lines.
Since the narrow line region is not homogeneous, two major types of models are
used: (a) those assuming a homogeneous gas distribution and a filling factor
less than unity to mimic the presence of the emitting clouds; (b) those based
on a composition of single-cloud models combined in order to obtain the
observed spectra. The first method is largely used but may induce to misleading
conclusions as shown in this paper. The second one is more appropriate, but
requires a large number of observed lines in order to limit the number of
single models used. After discussing the case of an extragalactic HII region,
for which the ionizing radiation spectrum is better known, we show that 1-D
models for the narrow line region with a filling factor less than unit do not
properly mimic the clumpiness, but just simulates an overall lower density.
Multi-cloud models lead to more reliable results. Both models are tested in
this paper, using the emission-line spectra of two well-known Seyfert galaxies,
NGC 4151 and NGC 1068. It is shown that ionizing radiation spectra with a blue
bump cannot be excluded by multi-cloud models, although excluded by Alexander
et al. (1999, 2000)using homogeneous models with a filling factor less than
unity.


title: Halting planet migration by photoevaporation from the central source

abstract:
  The recent discovery of Jupiter-mass planets orbiting at a few AU from their
stars compliments earlier detections of massive planets on very small orbits.
The short period orbits strongly suggest that planet migration has occurred,
with the likely mechanism being tidal interactions between the planets and the
gas disks out of which they formed. The newly discovered long period planets,
together with the gas giant planets in our solar system, show that migration is
either absent or rapidly halted in at least some systems. We propose a
mechanism for halting type-II migration at several AU in a gas disk.
Photoevaporation of the disk by irradiation from the central star can produce a
gap in the disk at a few AU, preventing planets outside the gap from migrating
down to the star. This would result in an excess of systems with planets at or
just outside the photoevaporation radius.


title:
Line profile variations in classical Cepheids. Evidence for non-radial
  pulsations?

abstract:
  We have investigated line profiles in a large sample of Cepheid spectra, and
found four stars that show unusual (for Cepheids) line profile structure (bumps
or/and asymmetries). The profiles can be phase dependent but the behavior
persists over many cycles. The asymmetries are unlikely to be due to the
spectroscopic binarity of these stars or the specific velocity field in their
atmospheres caused by shock waves. As a preliminary hypothesis, we suggest that
the observed features on the line profiles in the spectra of X Sgr, V1334 Cyg,
EV Sct and BG Cru can be caused by the non-radial oscillations. It is possible
that these non-radial oscillations are connected to resonances between the
radial modes (3.2, 7.5 or 10.0 days).


title:
3.1 $\mu$m H$_{2}$O Ice Absorption in LINER-Type Ultraluminous Infrared
  Galaxies with Cool Far-Infrared Colors: the Centrally-Concentrated Nature of
  Their Deeply Buried Energy Sources

abstract:
  Ground-based 2.8--4.1 $\mu$m slit spectra of the nuclei of seven
ultraluminous infrared galaxies (ULIRGs) that are classified optically as
LINERs and have cool far-infrared colors are presented. All the nuclei show 3.3
$\mu$m polycyclic aromatic hydrocarbon (PAH) emission, with equivalent widths
that are systematically lower than those in starburst galaxies. Strong 3.1
$\mu$m H$_{2}$O ice absorption, with optical depth greater than 0.6, is also
detected in five nuclei, and 3.4 $\mu$m carbonaceous dust absorption is
detected clearly in one of the five nuclei. It is quantitatively demonstrated
that the large optical depths of the H$_{2}$O ice absorption in the five
sources, and the 3.4 $\mu$m absorption in one source, are incompatible with a
geometry in which the energy sources are spatially mixed with dust and
molecular gas, as is expected for a typical starburst, but instead require that
a large amount of nuclear dust (including ice-covered grains) and molecular gas
be distributed in a screen in front of the 3--4 $\mu$m continuum-emitting
sources. This geometrical requirement can naturally be met if the energy
sources are more centrally concentrated than the nuclear dust and molecular
gas. The low equivalent widths of the PAH emission compared to starbursts and
the central concentration of the nuclear energy sources in these five ULIRGs
are best explained by the presence of energetically important active galactic
nuclei deeply buried in dust and molecular gas.


title: Distances to Nearby Galaxies in Sculptor

abstract:
  We present an analysis of Hubble Space Telescope/WFPC2 images of nine nearby
galaxies in Sculptor. We derive their distances from the luminosity of the tip
of the red giant branch stars with a typical accuracy of ~ 12%. Their distances
are 4.21 Mpc (Sc22), 4.92 Mpc (DDO226), 3.94 Mpc (NGC253), 3.40 Mpc (KDG2),
3.34 Mpc (DDO6), 3.42 Mpc (ESO540-030), 4.43 Mpc (ESO245-05), 4.27 Mpc
(UGCA442), and 3.91 Mpc (NGC7793). The galaxies are concentrated in several
spatially separated loose groups around NGC300, NGC253, and NGC7793. The
Sculptor galaxy complex together with the CVn I cloud and the Local Group form
a 10 Mpc amorphous filament, apparently driven by the free Hubble flow.


title: The Characteristics of Magnetic CVs in the Period Gap

abstract:
  We have observed several magnetic cataclysmic variables located in the range
between 2 and 3 hours, known as the period gap. This work was prompted by the
recent discovery of RX J1554.2+2721. It has 2.54 hours orbital period and shows
almost pure cyclotron continuum in a low luminosity state, similar to
HS1023+3900,
  HS0922+1333 and RBS206. These are low accretion rate polars (LARPs) known to
have mass transfer rates of order of a few 10^-13Msun/year.
  The aim of the study was to find out, if magnetic systems filling the period
gap are in any way different from their counterparts outside that range of
periods. The only significant difference we encounter, is much higher number of
asynchronous magnetic systems to-wards longer periods than below the gap.


title:
Four Numerical Approaches for Solving the Radiative Transfer Equation in
  Magnetized White-Dwarf Atmospheres

abstract:
  We compare four different methods to calculate radiative transfer through a
magnetized stellar atmosphere, and apply them to the case of magnetic white
dwarfs. All methods are numerically stable enough to allow determination of the
magnetic field structure, but distinctions between faster, simplifying,
methods, and elaborate, but more CPU-time consuming, methods, can be made.


title:
The galactic evolution of neutron star mergers and their possible effect
  on the galactic chemical enrichment of r-process elements

abstract:
  A population number synthesis code follows in detail the evolution of a
population of single stars and of close binaries. We use our code to simulate
the population of neutron star - neutron star and black hole - neutron star
binaries. We then combine our population number synthesis code with a galactic
chemical evolutionary model in order to follow the time evolution of the
formation and merger rate of these double compact star binaries and the
resulting chemical enrichment of r-process elements, over the whole Galactic
lifetime. It can be concluded that the neutron star/black hole merger process
is able to reproduce the observed r-process enrichment of the Galaxy. However,
we show that the latter conclusion depends critically on the physics of case BB
Roche lobe overflow in binaries with a neutron star component and a hydrogen
deficient core helium/helium shell burning star with a mass between 2.6 Mo and
6 Mo.


title:
Modelling the TeV gamma-ray spectra of two low redshift AGNs: Mkn 501
  and Mkn 421

abstract:
  We discuss the results of modelling the TeV gamma-ray spectra of two AGNs,
Mkn 501 and Mkn 421 that have almost the same redshifts: z=0.031 and z=0.034,
respectively. The effect of intergalactic gamma-ray absorption is treated as an
uncertainty in the measurement of the intrinsic spectrum. Although the objects
differ, we obtain satisfactory fits for both of them in a synchrotron
self-Compton scenario. Compared to previous models, our fits are characterised
by higher values of the Doppler factor (>= 50) and an electron injection
spectrum extending to higher energies (Gmax = 1.5x10^5). In the case of Mkn
421, the observed difference in spectral slope in X-rays and TeV gamma-rays
between the high and low states can be explained as a variation of a single
parameter - the maximum energy Gmax mc^2 at which electrons are injected.


title: The Collimated Wind in NGC 253

abstract:
  Near-infrared Fabry-Perot imaging has revealed H2 emission extended to about
130 pc from the disk of NGC 253. It is closely related to the hot plasma
observed in soft X-rays: filamentary H2 features are found at the edges of the
hot plasma. These are the places of direct interaction between a superwind and
its surrounding molecular gas. We suggest that the filamentary features
actually trace a more or less conical shell-like structure, whose tangential
line of sight to us is intensely observed. The H2 emission shell is most likely
from the molecular gas blown out or swept to the side by the hot plasma
outflow. Dust is associated with this molecular gas structure. The outflow is
tilted with respect to the disk, possibly suggesting the inhomogeneous nature
of the interstellar medium in which the starburst takes place.


title: AGB stars in the Magellanic Clouds. I. The C/M ratio

abstract:
  Regions of different metallicity have been identified in the Magellanic
Clouds by using the ratio between Asymptotic Giant Branch stars of spectral
type C and M. In the Large Magellanic Cloud the ratio appears to decrease
radially while in the Small Magellanic Cloud (SMC) there is no clear trend,
reflecting either the large extension of the SMC along the line of sight or a
more complex star formation history. The distribution of the C/M ratio is
clumpy and corresponds to a spread in [Fe/H] of 0.75 dex in both Clouds. There
is an indication of increasing C/M ratio, thus decreasing metallicity, towards
the Bridge region connecting the two Clouds.


title: The Evolutionary Status of Early-type Galaxies in Abell 2390

abstract:
  We explore the evolution of the early-type galaxy population in the rich
cluster Abell 2390 at z=0.23. For this purpose, we have obtained spectroscopic
data of 51 elliptical and lenticular galaxies with MOSCA at the 3.5 m telescope
on Calar Alto Observatory. As our investigation spans both a broad range in
luminosity (-22.3<M_B<-19.3) and a wide field of view (10'x10'), the
environmental dependence of different formation scenarios can be analysed in
detail as a function of radius from the cluster center. In this paper, we
present first results on the Faber-Jackson relation and, for a subsample of 14
galaxies with morphological and structural parameters from HST, we also
investigate the evolution of the Kormendy relation and the Fundamental Plane.
We find a mild luminosity evolution of the early-type galaxies in Abell 2390:
our objects are on average brighter by m_B~0.4 mag.


title:
Limits on diffusive shock acceleration in supernova remnants in the
  presence of cosmic-ray streaming instability and wave dissipation

abstract:
  The instability in the cosmic-ray precursor of a supernova shock moving in
interstellar medium is studied. The level of magnetohydrodynamic turbulence in
this region determines the maximum energy of particles accelerated by the
diffusive shock acceleration mechanism. The high efficiency of cosmic ray
acceleration is accepted, and the consideration is not limited by the case of
weak turbulence. It is assumed that Kolmogorov type nonlinear wave interactions
together with the ion-neutral collisions restrict the amplitude of random
magnetic field. As a result, the maximum energy of accelerated particles
strongly depends on the age of supernova remnant. The maximum energy can be as
high as $\sim10^{17}Z$ eV in young supernova remnants and falls down to about
$\sim10^{10}Z$ eV at the end of Sedov stage. Thus the standard estimate of
maximum particle energy based on the Bohm limit calculated for the interstellar
magnetic field strength is not justified in this case. This finding may explain
why the supernova remnants with the age more than a few thousand years are not
prominent sources of very high energy gamma-rays.


title: Curvaton reheating: an application to braneworld inflation

abstract:
  The curvaton was introduced recently as a distinct inflationary mechanism for
generating adiabatic density perturbations. Implicit in that scenario is that
the curvaton offers a new mechanism for reheating after inflation, as it is a
form of energy density not diluted by the inflationary expansion. We consider
curvaton reheating in the context of a braneworld inflation model, {\em steep
inflation}, which features a novel use of the braneworld to give a new
mechanism for ending inflation. The original steep inflation model featured
reheating by gravitational particle production, but the inefficiency of that
process brings observational difficulties. We demonstrate here that the
phenomenology of steep inflation is much improved by curvaton reheating.


title: Precise quasielastic neutrino/nucleon cross section

abstract:
  Quasielastic antineutrino/proton and neutrino/neutron scatterings can be well
approximated by simple formulae, valid around MeV or GeV energies. We obtain a
single expression valid in the whole range, and discuss its relevance for
studies of supernova neutrinos, which reach intermediate energies.


title: Magnetic field topology of accreting white dwarfs

abstract:
  We report first results of our systematic investigation of the magnetic field
structure of rotating single magnetic white dwarfs and of white dwarfs in
magnetic cataclysmic variables. The global magnetic field distributions on the
isolated white dwarf HE1045-0908 and the accreting white dwarfs in EF Eri and
CP Tuc have been derived from phase-resolved flux and polarization spectra
obtained with FORS1 at the ESO VLT using the systematic method of Zeeman
tomography.


title: Fireballs with a Neutron Component

abstract:
  Standard GRB fireballs must carry free neutrons. This crucially changes the
mechanism of fireball deceleration by an external medium. As the ion fireball
decelerates, the coasting neutrons form a leading front. They gradually decay,
leaving behind a relativistic trail of decay products mixed with the ambient
medium. The ion fireball sweeps up the trail and drives a shock wave in it.
Thus, observed afterglow emission is produced in the neutron trail. The impact
of neutrons turns off at 10^{17}cm from the explosion center, and here a
spectral transition is expected in GRB afterglows. Absence of neutron
signatures would point to absence of baryons and a dominant Poynting flux in
the fireballs.


title: Progress in modeling magnetic white dwarfs

abstract:
  First satisfactory fits to the flux spectrum and circular polarization of the
DAP Grw +70 8247 are presented, as well as a first model of the DBP GD 229 with
consistent helium line data.


title: The transverse velocity and excitation structure of the HH 110 jet

abstract:
  We present long-slit spectroscopic observations of the HH 110 jet obtained
with the 4.2~m William Herschel Telescope. We have obtained for the first time,
spectra for slit positions along and across the jet axis (at the position of
knots B, C, I, J and P) to search for the observational signatures of
entrainment and turbulence by studying the kinematics and the excitation
structure. We find that the HH 110 flow accelerates from a velocity of 35 km/s
in knot A up to 110 km/s in knot P. We find some systematic trends for the
variation of the emission line ratios along the jet. No clear trends for the
variation of the radial velocity are seen across the width of the jet beam. The
cross sections of the jet show complex radial velocity and line emission
structures which differ quite strongly from each other.


title:
Infrared and Visual Interstellar Absorption Features toward Heavily-
  Reddened Field Stars

abstract:
  We present measurements of the 3.4-micron hydrocarbon dust absorption
feature, and four visual diffuse interstellar bands, for twelve highly reddened
(9.0<A(V)<15.8), early-type stars identified from the Stephenson (1992)
catalogue, covering a range of Galactic longitude. The hydrocarbon feature is
detected in eleven sightlines with optical depths of up to 0.05, and
corresponding column densities are derived. The feature is weaker per unit A(V)
than previously reported, further underlining earlier observations of its
enhancement in the Galactic Centre. A comparison of the 3.4-micron feature
substructure indicates organic material similar to that seen in earlier diffuse
medium studies, suggesting a uniform formation history across the Galactic
disc. The profile is well matched by both meteoritic material and several
laboratory-prepared analogues. The diffuse interstellar bands (DIBs) measured
were at 6177, 6203, 6284 and 6614 Angstroms; no strong correlations were
detected, either between these bands themselves or between the DIBs and the
3.4-micron feature, although 6284 and 6614 appear to vary together. If the
carriers of the DIBs are organic and molecular in nature and have cosmic carbon
abundance requirements similar to those of the C-H stretch, these results imply
that there is little direct carbon exchange between them and the aliphatic dust
component. Measurements of the extinction to these objects suggest luminosity
anomalies similar to that already seen in Cyg OB2 No. 12.


title:
Abell 2255: Increased Star Formation and AGN Activity in a
  Cluster-Cluster Merger

abstract:
  Deep VLA 1.4 GHz radio continuum imaging of Abell 2255 is presented. This
cluster is among the better nearby candidates for rich cluster-cluster merger
systems, with evidence including an elongated X-ray morphology, the presence of
a radio halo, and substructure present in its galaxy distribution. Our radio
observations reach an rms sensitivity of ~40 uJy/beam, enabling us to detect
(at 5 sigma) star formation rates as low as 1.4 M(sun)/year from the center of
the cluster out to a radial distance of 3 Mpc. The radio data are complemented
by optical imaging and a large spectroscopic database, allowing us to separate
all galaxies with M_R < -20 into cluster members and foreground/background
galaxies. The spectra are also used to associate the galaxies' radio emission
with either star formation or AGN. We compare the resulting cluster radio
galaxy population with those of nineteen other nearby Abell clusters, and find
strong evidence for an increase in the frequency of radio galaxies in Abell
2255. This increase is seen in two separate types of galaxies: powerful radio
AGN and optically-faint star forming galaxies. The optical spectra of the
latter often indicate current or recent starbursts, and these galaxies appear
to be distributed along an axis perpendicular to the probable merger axis. We
assess these factors in light of models of galaxy evolution, and suggest that
the cluster-cluster merger is responsible for triggering galaxy activity in
Abell 2255.


title: Variability of Sagittarius A* - Flares at 1 Millimeter

abstract:
  We report the results from recent observations of Sgr A* at
short-/sub-millimeter wavelengths made with the partially finished
Sub-Millimeter Array (SMA) on Mauna Kea. A total of 25 epochs of observations
were carried out over the past 15 months in 2001 March to 2002 May. Noticeable
variations in flux density at 1.3 mm were observed showing three ``flares''.
The SMA observations suggest that Sgr A* highly increases towards submillimeter
wavelengths during a flare suggesting the presence of a break wavelength in
spectral index around 3 mm. A cross-correlation of the SMA data at 1 mm with
the VLA data at 1 cm show a global delay of $t_{delay} > 3d$, suggesting that
sub-millimeter wavelengths tend to peak first. Only marginal day-to-day
variations in flux density (2-3 $\sigma$) have been detected at 1.3 mm. No
significant flares on a short time scale ($\sim1$ hr) have been observed at 1.3
mm. We also failed to detect significant periodic signals at a level of 5%
(3$\sigma$) from Sgr A* in a periodic searching window ranging from 10 min to
2.5 hr. The flares observed at the wavelengths between short-centimeter and
sub-millimeter might be a result of collective mass ejections associated with
X-ray flares that originate from the inner region of the accretion disk near
the supermassive black hole.


title:
The impact of alpha/Fe enhanced stellar evolutionary tracks on the ages
  of elliptical galaxies

abstract:
  We complement our study of alpha/Fe enhanced stellar population models of
Lick absorption indices (Thomas et al. 2003) by comparing two sets of alpha/Fe
enhanced models. In both models the impact on Lick indices due to alpha/Fe
enhancement is accounted for through a modification of the stellar absorption
line-strengths using the response functions of Tripicco & Bell (1995). One set
of models, however, uses solar-scaled, the other alpha/Fe enhanced stellar
evolutionary tracks. Since the alpha/Fe enhanced tracks are hotter than the
solar-scaled ones (Salasnich et al. 2000), the correspondent stellar population
models have slightly weaker metallic indices (i.e. Mgb, <Fe> etc.) and stronger
Balmer line indices (Hbeta) (Maraston et al 2003). Here we explore
quantitatively the impact of this effect on the alpha/Fe ratios, metallicities
and ages that are derived for elliptical galaxies. We find that the modest
decrease of the metallic indices Mgb and <Fe> balance each other, such that
fully consistent alpha/Fe ratios are derived for stellar systems using alpha/Fe
enhanced models with either solar-scaled or alpha/Fe enhanced stellar tracks.
The decrease of the metallic indices and the increase of Hbeta conspire in a
way that also consistent metallicities are obtained. The derived ages, instead,
are significantly different. The inclusion of alpha/Fe enhanced stellar tracks
leads to the derivation of ages as high as 30 Gyr for elliptical galaxies. For
the same objects, ages not older than 15 Gyr are obtained, if alpha/Fe enhanced
models using solar-scaled tracks are adopted. This may indicate that current
stellar evolutionary models overestimate the bluing of stellar evolutionary
tracks due to alpha/Fe enhanced chemical mixtures at super-solar metallicities.


title:
Future Type Ia Supernova Data as Tests of Dark Energy from Modified
  Friedmann Equations

abstract:
  In the Cardassian model, dark energy density arises from modifications to the
Friedmann equation, which becomes $H^2 = g(\rhom)$, where $g(\rhom)$ is a new
function of the energy density. The universe is flat, matter dominated, and
accelerating. The distance redshift relation predictions of generalized
Cardassian models can be very different from generic quintessence models, and
can be differentiated with data from upcoming pencil beam surveys of Type Ia
Supernovae such as SNAP. We have found the interesting result that, once
$\Omega_m$ is known to 10% accuracy, SNAP will be able to determine the sign of
the time dependence of the dark energy density. Knowledge of this sign (which
is related to the weak energy condition) will provide a first discrimination
between various cosmological models that fit the current observational data
(cosmological constant, quintessence, Cardassian expansion). Further, we have
performed Monte Carlo simulations to illustrate how well one can reproduce the
form of the dark energy density with SNAP.
  To be concrete we study a class of two parameter ($n$,$q$) generalized
Cardassian models that includes the original Cardassian model (parametrized by
$n$ only) as a special case. Examples are given of MP Cardassian models that
fit current supernovae and CMB data, and prospects for differentiating between
MP Cardassian and other models in future data are discussed. We also note that
some Cardassian models can satisfy the weak energy condition $w>-1$ even with a
dark energy component that has an effective equation of state $w_X < -1$.


title:
Tree-Particle-Mesh: an adaptive, efficient, and parallel code for
  collisionless cosmological simulation

abstract:
  An improved implementation of an N-body code for simulating collisionless
cosmological dynamics is presented. TPM (Tree-Particle-Mesh) combines the PM
method on large scales with a tree code to handle particle-particle
interactions at small separations. After the global PM forces are calculated,
spatially distinct regions above a given density contrast are located; the tree
code calculates the gravitational interactions inside these denser objects at
higher spatial and temporal resolution. The new implementation includes
individual particle time steps within trees, an improved treatment of tidal
forces on trees, new criteria for higher force resolution and choice of time
step, and parallel treatment of large trees. TPM is compared to P^3M and a tree
code (GADGET) and is found to give equivalent results in significantly less
time. The implementation is highly portable (requiring a Fortran compiler and
MPI) and efficient on parallel machines. The source code can be found at
http://astro.princeton.edu/~bode/TPM/


title:
A Comprehensive Radio and Optical Study of Abell 2256: Activity from an
  Infalling Group

abstract:
  Abell 2256 is a nearby (z~0.06), rich cluster of galaxies with fascinating
observed properties across a range of wavelengths. Long believed to represent a
cluster merger, recent X-ray and optical results have suggested that in
addition to the primary cluster and subcluster there is evidence for a third,
poorer system. We present wide-field, high sensitivity 1.4 GHz VLA radio
observations of Abell 2256 in conjunction with optical imaging and additional
spectroscopy. Over 40 cluster radio galaxies are identified, with optical
spectroscopy indicating the emission source (star formation or AGN) for most of
them. While the overall fraction of galaxies exhibiting radio emission is
consistent with a large sample of other nearby clusters, we find an increase in
the activity level of galaxies belonging to the third system (hereafter, the
``Group''). Specifically, the Group has relatively more star formation than
both the primary cluster and main subcluster. The position of the Group is also
coincident with the observed cluster radio relic. We suggest that the Group
recently (~0.3 Gyr) merged with the primary cluster and that this merger, not
the ongoing merger of the primary and the main subcluster, might be responsible
for many of the unusual radio properties of Abell 2256. Furthermore, the
greater star formation activity of the Group suggests that the infall of groups
is an important driver of galaxy evolution in clusters.


title:
Cosmological constraints from the cluster contribution to the power
  spectrum of the soft X-ray background. New evidence for a low sigma_8

abstract:
  We use the X-ray power spectrum of the ROSAT all-sky survey in the R6 band
(approximately 0.9-1.3 keV) to set an upper limit on the galaxy cluster power
spectrum. The cluster power spectrum is modelled with a minimum number of
robust assumptions regarding the structure of the clusters. The power spectrum
of ROSAT sets an upper limit on the Omega_m-sigma_8 plane which excludes all
the models with sigma_8 above sigma_8 = 0.5/(Omega_m^0.38) in a flat LCDM
universe. We discuss the possible sources of systematic errors in our
conclusions, mainly dominated by the assumed L_x-T relation. Alternatively,
this relation could be constrained by using the X-ray power spectrum, if the
cosmological model is known. Our conclusions suggest that only models with a
low value of sigma_8 (sigma_8 < 0.8 for Omega_m = 0.3) may be compatible with
our upper limit. We also find that models predicting lower luminosities in
galaxy clusters are favoured. Reconciling our cosmological constraints with
these arising by other methods might require either a high entropy floor or
wide-spread presence of cooling flows in the low-redshift clusters.


title: Time-resolved Spectroscopy of the M15 X-ray Binary AC211/X2127+119

abstract:
  We present time-resolved spectroscopy acquired during two epochs (spaced
apart by ~15 days) of the eclipsing Low Mass X-ray Binary AC211/X2127+119 in
the globular cluster M15. The spectra show variations in the HeII 4686 emission
line not only modulated on the orbital period, but also on time-scales of a few
days. During the first epoch of observation, the emission line shows a strong
S-wave superimposed on the average double-peaked profile. The line exhibits no
evidence of rotational disturbance at the orbital phases when the eclipse is
observed in the optical continuum. During the second epoch, no double-peak or
S-wave component is present. The HeI absorption lines detected by other authors
are not present in our spectra. A Doppler image of the HeII 4686 for the first
epoch supports the presence of the accretion disc. No hotspot is detected,
although enhanced emission at V_X=30km/s, V_Y=160 km/s is observed. We discuss
the implications of this emission in the context of an X-ray heated donor star,
in which case a high mass ratio and neutron star primary are implied. Finally,
we speculate on the possibility of a misaligned secondary star in AC211.


title:
Testing two nuclear physics approximations used in the standard leaky
  box model for the spallogenic production of LiBeB

abstract:
  The spallative production rates of Lithium, Beryllium and Boron (LiBeB) are a
necessary component in any calculation of the evolution of these nuclei in the
Galaxy. Previous calculations of these rates relied on two assumptions relating
to the nuclear physics aspects: the straight-ahead approximation that describes
the distribution of fragment energies and the assumption that the major
contributor to the production rate arises from single-step reactions between
primary cosmic ray projectiles and interstellar medium targets. We examine both
assumptions by using a semi-empirical description for the spall's energy
distribution and by including the reactions that proceed via intermediary
fragments. After relaxing the straight-ahead approximation we find the changes
in the production rates and emerging fluxes are small and do not warrant
rejection of this approximation. In contrast we discover that two-step
reactions can alter the production rate considerably leading to noticeable
increases in the efficiency of producing the LiBeB nuclei. Motivated by this
result we introduce a cascade technique to compute the production rates exactly
and find that the results differ only slightly from those of our two-step
calculations. We thus conclude that terminating the reaction network at the
two-step order is sufficiently accurate for current studies of spallation.


title: Molecular Hydrogen Optical Depth Templates for FUSE Data Analysis

abstract:
  The calculation and use of molecular hydrogen optical depth templates to
quickly identify and model molecular hydrogen absorption features longward of
the Lyman edge at 912 Angstroms are described. Such features are commonly
encountered in spectra obtained by the Far Ultraviolet Spectroscopic Explorer
and also in spectra obtained by the Space Telescope Imaging Spectrograph,
albeit less commonly. Individual templates are calculated containing all the
Lyman and Werner transitions originating from a single rotational state (J'')
of the 0th vibrational level (v'') of the ground electronic state. Templates
are provided with 0.01 Angstrom sampling for doppler parameters ranging from 2
<= b <= 20 km s^-1 and rotational states 0 <= J'' <= 15. Optical depth
templates for excited vibrational states are also available for select doppler
parameters. Each template is calculated for a fiducial column density of
log[N(cm^-2)] = 21 and may be scaled to any column less than this value without
loss of accuracy. These templates will facilitate the determination of the
distribution of molecular hydrogen column density as a function of rotational
level. The use of these templates will free the user from the computationally
intensive task of calculating profiles for a large number of lines and allow
concentration on line profile or curve-of-growth fitting to determine column
densities and doppler parameters. The templates may be downloaded freely from
http://www.pha.jhu.edu/~stephan/h2ools2.html


title:
Supernova Observation Via Neutrino-Nucleus Elastic Scattering in the
  CLEAN Detector

abstract:
  Development of large mass detectors for low-energy neutrinos and dark matter
may allow supernova detection via neutrino-nucleus elastic scattering. An
elastic-scattering detector could observe a few, or more, events per ton for a
galactic supernova at 10 kpc ($3.1 \times 10^{20}$ m). This large yield, a
factor of at least 20 greater than that for existing light-water detectors,
arises because of the very large coherent cross section and the sensitivity to
all flavors of neutrinos and antineutrinos. An elastic scattering detector can
provide important information on the flux and spectrum of $\nu_\mu$ and
$\nu_\tau$ from supernovae. We consider many detectors and a range of target
materials from $^4$He to $^{208}$Pb. Monte Carlo simulations of low-energy
backgrounds are presented for the liquid-neon-based Cryogenic Low Energy
Astrophysics with Noble gases (CLEAN) detector. The simulated background is
much smaller than the expected signal from a galactic supernova.


title: Suppression of thermal conduction in non-cooling flow clusters

abstract:
  Recent X-ray observations have revealed a universal temperature profile of
the intracluster gas of non-cooling flow clusters which is flat for r \le 0.2
r_{180}. Numerical simulations, however, obtain a steeper temperature profile
in the inner region. We study the effect of thermal conduction on the
intracluster gas in non-cooling flow clusters in light of these observations,
using the steep temperature profiles obtained by authors of numerical
simulations. We find that given 10^{10} yr for the intracluster gas to evolve,
thermal conduction should be suppressed from the classical value by a factor
\sim 10^{-3} in order to explain the observations.


title: Hard X-ray Observations of Magnetic Cataclysmic Variables

abstract:
  Hard X-ray light curves and spectral parameters from our analysis of X-ray
data of five AM Her type systems - V2301 Oph, V1432 Aql, EP Draconis, GG
Leonis, V834 Cen, and one intermediate polar - TV Col, observed using the Rossi
X-ray Timing Explorer satellite are presented. A new improved ephemeris has
been derived for V2301 Oph using the mid-eclipse timings. Average intensity
variations, without any change of shape of the light curve or hardness ratio,
are observed on timescales of a few days to a few months in V2301 Oph. V1432
Aql shows erratic variations on a timescale of a day, at least 2 sharp dips
near orbital phases 0.35 and 0.5, and a total eclipse. Hard X-ray eclipses are
also reported in EP Dra and GG Leo. V834 Cen shows intensity variations on
yearly timescale and is found to be in a low state in 2002. In TV Col, a binary
orbital modulation at 5.5h, in addition to the spin period of 1910s, is
reported for the first time. Maximum spectral temperatures in Polars have been
determined and used to estimate the masses of the white dwarfs.


title:
Beyond the standard accretion disc model: coupled magnetic disc--corona
  solutions with a physically motivated viscosity law

abstract:
  We present a systematic, analytical study of geometrically thin, optically
thick accretion disc solutions for magnetized turbulent flows, with an
alpha-like viscosity prescription. Under the only assumptions that (1)
Magneto-Rotational instability (MRI) generates the turbulence that produces the
anomalous viscosity needed for accretion to proceed, and that (2) the magnetic
field amplified by the instability saturates due to buoyant vertical escape, we
are able to self-consistently solve the disc structure equations including the
fraction of power, f, that is carried off by vertical Poynting flux (and likely
dissipated outside the optically thick disc). For low-viscosity discs, we
obtain stable high-f solutions at low accretion rates, when gas pressure
dominates, and unstable, low-f, radiation pressure dominated solutions at high
accretion rates. For high viscosity discs, instead, a new thermally and
viscously stable, radiation pressure dominated solution is found, characterized
by f~1 and appearing only above a critical accretion rate (of the order of few
tenths of the Eddington one). We discuss the regimes of validity of our
assumptions, and the astrophysical relevance of our solutions. We conclude that
our newly discovered thin disc solutions, possibly accompanied by powerful,
magnetically dominated coronae and outflows, should be seriously considered as
models for black holes accreting at super-Eddington rates.


title: More lead stars

abstract:
  The standard model for the operation of the s-process in asymptotic giant
branch (AGB) stars predicts that low-metallicity ([Fe/H] <= -1) AGB stars
should exhibit large overabundances of Pb and Bi as compared to other
s-elements. Eight CH stars (with [Fe/H] ranging from -1.5 to -2.5) are studied
in the present paper using high-resolution spectra (R = lambda/Delta lambda =
135 000), and five of them appear to be enriched in lead (with [Pb/Ce] ~ 0.7).
Abundances of heavy elements in these `lead stars' (defined as stars enriched
in s-elements and with [Pb/hs] >= 1, hs being any of Ba, La or Ce) are
consistent with the predictions for the s-process operating in low-metallicity
AGB stars as a consequence of the `partial mixing' of protons below the
convective hydrogen envelope. Two among the studied stars (HD 189711 and V Ari)
add to a growing number of low-metallicity stars which do not conform to these
predictions, however. Variations on the canonical proton-mixing scenario for
the operation of the s-process in low-metallicity stars, that could account for
these discrepant stars, are briefly discussed.


title:
Searching for Planetary Transits in the Field of Open Cluster NGC 6819 -
  I

abstract:
  We present results from our survey for planetary transits in the field of the
intermediate age (~2.5 Gyr), metal-rich ([Fe/H]~+0.07) open cluster NGC 6819.
We have obtained high-precision time-series photometry for over 38,000 stars in
this field and have developed an effective matched-filter algorithm to search
for photometric transits. This algorithm identified 8 candidate stars showing
multiple transit-like events, plus 3 stars with single eclipses. On closer
inspection, while most are shown to be low mass stellar binaries, some of these
events could be due to brown dwarf companions. The data for one of the
single-transit candidates indicates a minimum radius for the companion similar
to that of HD 209458b.


title:
An effect of stimulated radiation processes on radio emission from
  extended sources

abstract:
  Both the standard theory of thermal radio emission and the synchrotron theory
encounter some difficulties. The most crucial for the former one is
nonpossibility to explain the radio spectrum of Venus in the decimeter range
(Ksanfomality 1985). The radio spectra of planetary nebulae at high frequencies
also are not comfortably consistent with the standard theory (Siodmiak &
Tylenda 2001). Here we show that the account for an induced character of
radiation processes sufficiently improves the predictions of the standard
theory.
  Moreover, the developed here theory of radio emission from non-uniform gas
gives the radio spectra of extended sources, such as supernova remnants and
radio galaxies, which are normally attributed to the synchrotron emission. It
is important, in this aspect, that the synchrotron self-absorption produces a
change in the polarization position angle across the spectral peak. No such a
change was detected in gigahertz-peaked spectrum sources (Mutoh et al. 2002).
Besides, the flat or slightly inverted radio spectra of low-luminosity active
galactic nuclei are not easily consistent with the synchrotron radiation
mechanism (Nagar, Wilson & Falcke 2001, Ulvestad & Ho 2001).
  Thermal radiation in a magnetic field is polarized (see, e.g., Lang 1978).
This is also true for radiation considered in the present paper, which can be
described as incoherent induced radiation (Prigara 2001b).


title:
Component separation for Cosmic Microwave Background data: a blind
  approach based on spectral diversity

abstract:
  We present a blind multi-detector multi-component spectral matching method
for all sky observations of the cosmic microwave background, working on the
spherical harmonics basis. The method allows to estimate on a set of
observation maps the power spectra of various components present in CMB data,
their contribution levels in each detector and the noise levels. The method
accounts for the instrumental effect of beam convolution. We have implemented
the method on all sky Planck simulations containing five components and white
noise, including beam smoothing effects.


title:
Photometric properties of theoretical spectral libraries for GAIA
  photometry

abstract:
  Photometric properties of various spectral libraries of synthetic stellar
spectra derived from the ATLAS 9 (Castelli et al. 1997), the PHOENIX NextGen
(Hauschildt et al. 1999a, 1999b), the NMARCS (Bessell et al. 1998), and the
BaSeL (Lejeune et al. 1998, Westera et al. 2002) models are discussed in view
of their application to the definition of the GAIA photometric system.
Comparisons with empirical UBVRI calibrations show significant discrepancies at
low temperatures between the different models, and with respect to the \basel
3.1 and the Alonso et al. (1998, 1999) empirical calibrations.


title: The radio halo in the merging cluster A3562

abstract:
  we present new VLA observations at 1.4 GHz confirming the presence of a radio
halo at the centre of the cluster A3562, in the core of the Shapley
Concentration. We also report a detailed multifrequency radio study of the head
tail galaxy J1333--3141, which is completely embedded in the halo emission. The
radio halo has an irregular shape, and a largest linear size of $\sim$ 620 kpc,
which is among the smallest found in the literature. The source has a steep
spectrum, i.e. $\alpha_{843 MHz}^{1.4 GHz} \sim 2$, and its total radio power,
P$_{1.4 GHz} \sim 2 \times10^{23}$ W Hz$^{-1}$, is the lowest known to date.The
radio power of the halo and the X-ray parameters of the cluster, such as L$_X$
and kT, nicely fit the correlations found in the literature for the other halo
clusters, extending them to low radio powers. We found that the total number of
electrons injected in the cluster environment by the head--tail source is
enough to feed the halo, if we assume that the galaxy has been radio active
over a large fraction of its crossing time. We discuss possible origins of the
radio halo in the light of the two--phase model (Brunetti et al. 2001) and
propose that the observed scenario is the result of a young source at the
beginning of the reacceleration phase.


title: Galactic Evolution along the Hubble Sequence

abstract:
  A generalization of the multiphase chemical evolution model applied to a wide
set of theoretical galaxies is shown. This set of models has been computed by
using the so-called Universal Rotation Curve from Persic, Salucci & Steel to
calculate the radial mass distributions of each theoretical galaxy. By assuming
that the molecular cloud and star formation efficiencies depend on the
morphological type of each galaxy, we construct a bi-parametric grid of models
whose results are valid in principle for any spiral galaxy, of given maximum
rotation velocity or total mass, and morphological type.


title: Cosmic ray spectrum and anisotropies from the knee to the second knee

abstract:
  We consider the scenario in which the knee in the cosmic ray spectrum is due
to a change in the escape mechanism of cosmic rays from the Galaxy from one
dominated by transverse diffusion to one dominated by drifts. We show that this
scenario explains not only the changes in spectral slope at the knee and at the
second knee, but can also account for the main characteristics of the observed
energy dependent anisotropy amplitude and phase of first harmonic in the energy
range between $10^{15}$ and $10^{18}$ eV. This provides a useful handle to
distinguish this diffusion/drift model from other scenarios proposed to explain
the knee in the spectrum.


title:
The superwind mass-loss rate of the metal-poor carbon star LI-LMC 1813
  in the LMC cluster KMHK 1603

abstract:
  LI-LMC 1813 is a dust-enshrouded Asymptotic Giant Branch (AGB) star, located
in the small open cluster KMHK 1603 near the rim of the Large Magellanic Cloud
(LMC). Optical and infrared photometry between 0.5 and 60 micron is obtained to
constrain the spectral energy distribution of LI-LMC 1813. Near-infrared
spectra unambiguously show it to be a carbon star. Modelling with the radiation
transfer code Dusty yields accurate values for the bolometric luminosity, L=1.5
x 10^4 Lsun, and mass-loss rate, Mdot=3.7(+/-1.2) x 10^-5 Msun/yr. On the basis
of colour-magnitude diagrams, the age of the cluster KMHK 1603 is estimated to
be t=0.9-1.0 Gyr, which implies a Zero-Age Main Sequence mass for LI-LMC 1813
of M(ZAMS)=2.2+/-0.1 Msun. This makes LI-LMC 1813 arguably the object with the
most accurately and reliably determined (circum)stellar parameters amongst all
carbon stars in the superwind phase.


title:
Close stars and an inactive accretion disk in Sgr A*: Eclipses and
  flares

abstract:
  A cold neutral and extremely dim accretion disk may be present as a remnant
of a past vigorous activity around the black hole in our Galactic Center (GC).
Here we discuss ways to detect such a disk through its interaction with
numerous stars present in the central ~0.1 parsec of the Galaxy. The first
major effect expected is X-ray and near infrared (NIR) flares arising when
stars pass through the disk. The second is eclipses of the stars by the disk.
We point out conditions under which the properties of the expected X-ray flares
are similar to those recently discovered by Chandra. Since orbits of bright
stars are now being precisely measured, the combination of the expected flares
and eclipses offers an invaluable tool for constraining the disk density, size,
plane and even direction of rotation. The winds of the O-type stars are
optically thick to free-free absorption in radio frequencies. If present near
Sgr A* core, such powerful stellar winds can modulate and even occult the radio
source.


title:
Late reionizations of the Universe and their manifestation in the CMB
  data

abstract:
  We investigate two sets of two-epoched reionization models and their
manifestation in the CMB anisotropy and polarization data of the recent WMAP
project and make some predictions for the future PLANCK missions. In the first
set of models, the universe was reionized twice, first at z~15 by population
III stars and then at z~6 by stars in large galaxies. In the second set of
models, the extra peak-like reionization at high redshifts z > 100 is induced
by the decay of unstable particles, followed by the standard picture of
reionization at z~6. We examine the general properties of these two-epoched
reionization models and their implication in the WMAP CMB temperature
anisotropy-polarization cross-correlation. We have shown that these models have
comparable likelihood values for the WMAP data and distinct characters which
can be tested with the Planck high sensitivities.


title: How to determine the star formation histories in spiral disks

abstract:
  We have computed 500 chemical evolution models for the galaxy NGC 4303. With
the obtained evolutionary histories and a synthesis model we have also
calculated the spectral indices Mg2 and Fe5270. Fom the 500 models, by using a
chi-square technique, we obtain those reproducing the present day observations
within a confidence level of 95 %, reducing the number of possible models to
19. Only 6 of them are also able to reproduce the spectral indices radial
distributions with the same level of confidence. We conclude that this
technique of combining chemical with evolutionary synthesis models is a very
powerful tool, and, therefore, we propose to perform more observational
campaigns to obtain these and other spectral indices in spiral and irregular
galaxies.


title: Cluster Sunyaev-Zeldovich Effect Scaling Relations

abstract:
  X-ray observations of an "entropy floor" in nearby groups and clusters of
galaxies offer evidence that important non-gravitational processes, such as
radiative cooling and/or "preheating", have strongly influenced the evolution
of the intracluster medium (ICM). We examine how the presence of an entropy
floor modifies the thermal Sunyaev-Zeldovich (SZ) effect. A detailed analysis
of scaling relations between X-ray and SZ effect observables and also between
the two primary SZ effect observables is presented. We find that relationships
between the central Compton parameter and the temperature or mass of a cluster
are extremely sensitive to the presence of an entropy floor. The same is true
for correlations between the integrated Compton parameter and the X-ray
luminosity or the central Compton parameter. In fact, if the entropy floor is
as high as inferred in recent analyses of X-ray data, a comparison of these
correlations with both current and future SZ effect observations should show a
clear signature of this excess entropy. Moreover, because the SZ effect is
redshift-independent, the relations can potentially be used to track the
evolution of the cluster gas and possibly discriminate between the possible
sources of the excess entropy. To facilitate comparisons with observations, we
provide analytic fits to these scaling relations.


title: The XMM-Newton View of the Nucleus of NGC 4261

abstract:
  We present the first results from an XMM-Newton observation of the FRI galaxy
NGC 4261, which harbors a supermassive black hole and a low-ionization nuclear
emission-line region (LINER). Here we focus on the X-ray properties of the
nucleus, using the EPIC pn data. The 0.6-10 keV continuum in best fitted by a
thermal component with kT ~0.7 keV, plus a power law with photon index ~1.4,
absorbed by a column density NH~4e22 cm-2. An unresolved Fe K emission line
with EW 280 eV is detected at 7 keV. We also detect, for the first time,
short-term flux variability from the nucleus, on a timescale of 3-5 ks. The
short-term variations rule out an ADAF as the only production mechanism of the
X-ray continuum. Instead, we argue that the inner jet contributes to the
emission in the X-ray band.


title:
High-Resolution Observations of Interstellar Ca I Absorption --
  Implications for Depletions and Electron Densities in Diffuse Clouds

abstract:
  We present high-resolution (FWHM ~ 0.3-1.5 km/s) spectra of interstellar Ca I
absorption toward 30 Galactic stars. Comparisons of the column densities of Ca
I, Ca II, K I, and other species -- for individual components identified in the
line profiles and also when integrated over entire lines of sight -- yield
information on relative electron densities and depletions. There is no obvious
relationship between the ratio N(Ca I)/N(Ca II) [equal to n_e/(Gamma/alpha_r)
for photoionization equilibrium] and the fraction of hydrogen in molecular form
f(H2) (often taken to be indicative of the local density n_H). For a smaller
sample of sightlines for which the thermal pressure (n_H T) and local density
can be estimated via analysis of the C I fine-structure excitation, the average
electron density inferred from C, Na, and K (assuming photoionization
equilibrium) seems to be independent of n_H and n_H T. While the n_e obtained
from the ratio N(Ca I)/N(Ca II) is often significantly higher than the values
derived from other elements, the patterns of relative n_e derived from
different elements show both similarities and differences for different lines
of sight -- suggesting that additional processes besides photoionization and
radiative recombination commonly and significantly affect the ionization
balance of heavy elements in diffuse IS clouds. Such additional processes may
also contribute to the (apparently) larger than expected fractional ionizations
(n_e/n_H) found for some lines of sight with independent determinations of n_H.
In general, inclusion of ``grain-assisted'' recombination does reduce the
inferred n_e, but it does not reconcile the n_e estimated from different
elements. The depletion of calcium may have a much weaker dependence on density
than was suggested by earlier comparisons with CH and CN.


title: Chemical Evolution of CNO abundances

abstract:
  New low and intermediate star yields calculated by Buell (1997) are evaluated
by using them in a Galactic Chemical Evolution model. We analyze their effects
on CNO elemental abundances


title:
Foreground separation using a flexible maximum-entropy algorithm: an
  application to COBE data

abstract:
  A flexible maximum-entropy component separation algorithm is presented that
accommodates anisotropic noise, incomplete sky-coverage and uncertainties in
the spectral parameters of foregrounds. The capabilities of the method are
determined by first applying it to simulated spherical microwave data sets
emulating the COBE-DMR, COBE-DIRBE and Haslam surveys. Using these simulations
we find that is very difficult to determine unambiguously the spectral
parameters of the galactic components for this data set due to their high level
of noise. Nevertheless, we show that is possible to find a robust CMB
reconstruction, especially at the high galactic latitude. The method is then
applied to these real data sets to obtain reconstructions of the CMB component
and galactic foreground emission over the whole sky. The best reconstructions
are found for values of the spectral parameters: T_d=19 K, alpha_d=2,
beta_ff=-0.19 and beta_syn=-0.8. The CMB map has been recovered with an
estimated statistical error of \sim 22 muK on an angular scale of 7 degrees
outside the galactic cut whereas the low galactic latitude region presents
contamination from the foreground emissions.


title: Dispersion in modeled abundances

abstract:
  Chemical abundance data for the Galaxy show a wide dispersion. We try to
check if this dispersion may also be found with chemical evolution models as an
effect of variations of an Initial Mass Function (IMF) which follows a
Poisson's distribution


title:
Galactic Evolution along the Hubble Sequence.I. A grid of models
  parametrized by initial galaxy mass distribution

abstract:
  We present a generalization of the multiphase chemical evolution model
applied to a wide set of theoretical galaxies with different masses and
morphological types. This generalized set of models has been computed using the
so-called Universal Rotation Curve from Persic, Salucci & Steel (1996) to
calculate the radial mass distribution of 44 theoretical protogalaxies. This
distribution is a fundamental input which, besides its own effect on the galaxy
evolution, defines the characteristic collapse time scale or gas infall rate
onto the disk. For each mass radial distribution, we have 10 different
evolutionary rates. With these two hypotheses we construct a bi-parametric grid
of models. The results include the time evolution of different regions of the
disk and the halo along the galactocentric distance, measured by the gas and
stellar masses, the star formation rate and chemical abundances of 15 elements.


title:
CMB power spectrum estimation and map reconstruction with the
  Expectation - Maximization algorithm

abstract:
  We apply the iterative Expectation-Maximization algorithm (EM) to estimate
the power spectrum of the CMB from multifrequency microwave maps. In addition,
we are also able to provide a reconstruction of the CMB map. By assuming that
the combined emission of the foregrounds plus the instrumental noise is
Gaussian distributed in Fourier space, we have simplified the EM procedure
finding an analytical expression for the maximization step. By using the
simplified expression the CPU time can be greatly reduced. We test the
stability of our power spectrum estimator with realistic simulations of Planck
data, including point sources and allowing for spatial variation of the
frequency dependence of the Galactic emissions. Without prior information about
any of the components, our new estimator can recover the CMB power spectrum up
to scales l~1500 with less than 10% error. This result is significantly
improved if the brightest point sources are removed before applying our
estimator. In this way, the CMB power spectrum can be recovered up to l~1700
with 10% error and up to l~2100 with 50% error. This result is very close to
the one that would be obtained in the ideal case of only CMB plus white noise,
for which all our assumptions are satisfied. Moreover, the EM algorithm also
provides an straightforward mechanism to reconstruct the CMB map. The recovered
cosmological signal shows a high degree of correlation (r = 0.98) with the
input map and low residuals.


title:
Towards New Tests of Strong-field Gravity with Measurements of Surface
  Atomic Line Redshifts from Neutron Stars

abstract:
  In contrast to gravity in the weak-field regime, which has been subject to
numerous experimental tests, gravity in the strong-field regime is largely
unconstrained by observations. We show that gravity theories that cannot be
rejected by solar system tests but that diverge from general relativity in the
strong-field regime predict neutron stars with significantly different
properties than their general relativistic counterparts. In particular, the
range of redshifts of surface atomic lines predicted by such gravity theories
is significantly larger than the uncertainty introduced by our lack of
knowledge of the equation of state of ultra-dense matter. Measurements of such
redshifted lines with current X-ray observatories such as Chandra and
XMM-Newton can thus provide interesting new constraints on strong-field
gravity.


title: Star Formation in a Multi-Phase ISM

abstract:
  We present a 3d code for the dynamical evolution of a multi-phase
interstellar medium (ISM) coupled to stars via star formation (SF) and feedback
processes. The multi-phase ISM consists of clouds (sticky particles) and
diffuse gas (SPH): exchange of matter, energy and momentum is achieved by drag
(due to ram pressure) and condensation or evaporation processes. The cycle of
matter is completed by SF and feedback by SNe and PNe. A SF scheme based on a
variable SF efficiency as proposed by Elmegreen & Efremov (1997) is presented.
For a Milky Way type galaxy we get a SF rate of ~1 M_sun/yr with an average SF
efficiency of ~5%.


title: What can we learn about extragalactic radio jets from X-ray data?

abstract:
  We review the current status of resolved X-ray emission associated with
extragalactic radio jets and hotspots. The primary question for any particular
jet is to decide if the X-rays come from the synchrotron process or from
inverse Compton scattering. There is considerable evidence supporting
synchrotron emission for knots in the jets of FRI galaxies. For FRII terminal
hotspots detected in the X-ray band, synchrotron self-Compton emission
continues to provide viable models with one possible exception (so far).
Inverse Compton scattering on photons of the cosmic microwave background is
indicated for a few powerful jets, and is expected to be an important
contributor if not the dominating mechanism for higher redshift objects. The
application of a model generally yields physical parameters and in many cases,
these include the Doppler boosting factor.


title: Chemo-dynamical Evolution of the ISM in Galaxies

abstract:
  Chemo-dynamical models have been introduced in the late eighties and are a
generally accepted tool for understanding galaxy evolution. They have been
successfully applied to one-dimensional problems, e.g. the evolution of
non-rotating galaxies, and two-dimensional problems, e.g. the evolution of disk
galaxies. Recently, also three-dimensional chemo-dynamical models have become
available. In these models the dynamics of different components, i.e. dark
matter, stars and a multi-phase interstellar medium, are treated in a
self-consistent way and several processes allow for an exchange of matter,
energy and momentum between the components or different gas phases. Some
results of chemo-dynamical models and their comparison with observations of
chemical abundances or star formation histories will be reviewed.


title: Foregrounds for 21cm Observations of Neutral Gas at High Redshift

abstract:
  We investigate a number of potential foregrounds for an ambitious goal of
future radio telescopes such as the Square Kilometer Array (SKA) and Low
Frequency Array (LOFAR): spatial tomography of neutral gas at high redshift in
21cm emission. While the expected temperature fluctuations due to unresolved
radio point sources is highly uncertain, we point out that free-free emission
from the ionizing halos that reionized the universe should define a minimal
bound. This emission is likely to swamp the expected brightness temperature
fluctuations, making proposed detections of the angular patchwork of 21cm
emission across the sky unlikely to be viable. An alternative approach is to
discern the topology of reionization from spectral features due to 21cm
emission along a pencil-beam slice. This requires tight control of the
frequency-dependence of the beam in order to prevent foreground sources from
contributing excessive variance. We also investigate potential contamination by
galactic and extragalactic radio recombination lines (RRLs). These are unlikely
to be show-stoppers, although little is known about the distribution of RRLs
away from the Galactic plane. The mini-halo emission signal is always less than
that of the IGM, making mini-halos unlikely to be detectable. If they are seen,
it will be only in the very earliest stages of structure formation at high
redshift, when the spin temperature of the IGM has not yet decoupled from the
CMB.


title: Mirax: A Brazilian X-Ray Astronomy Satellite Mission

abstract:
  We describe the ``Monitor e Imageador de Raios-X'' (MIRAX), an X-ray
astronomy satellite mission proposed by the high energy astrophysics group at
the National Institute for Space Research (INPE) in Brazil to the Brazilian
Space Agency. MIRAX is an international collaboration that includes, besides
INPE, the University of California San Diego, the University of Tuebingen in
Germany, the Massachusetts Institute of Technology and the Space Research
Organization Netherlands. The payload of MIRAX will consist in two identical
hard X-ray cameras (10 -200 keV) and one soft X-ray camera (2-28 keV), both
with angular resolution of ~ 5-6 arcmin. The basic objective of MIRAX is to
carry out continuous broadband imaging spectroscopy observations of a large
source sample (~ 9 months/yr) in the central Galactic plane region. This will
allow the detection, localization, possible identification, and
spectral/temporal study of the entire history of transient phenomena to be
carried out in one single mission. MIRAX will have sensitivities of ~ 5
mCrab/day in the 2-10 keV band (~2 times better than the All Sky Monitor on
Rossi X-ray Timing Explorer) and 2.6 mCrab/day in the 10-100 keV band (~40
times better than the Earth Occultation technique of the Burst and Transient
Source Experiment on the Compton Gamma-Ray Observatory). The MIRAX spacecraft
will weigh about 200 kg and is expected to be launched in a low-altitude (~ 600
km) circular equatorial orbit around 2007/2008.


title:
Intermediate-Mass Black Holes in the Universe: A Review of Formation
  Theories and Observational Constraints

abstract:
  This paper reviews the subject of intermediate-mass black holes (IMBHs) with
masses between those of "stellar-mass" and "super-massive" black holes. The
existence of IMBHs is a real possibility: they might plausibly have formed as
remnants of the first generation of stars (Population III), as the result of
dense star cluster evolution, or as part of the formation process of
super-massive black holes. Their cosmic mass density could exceed that of
super-massive black holes (Omega = 10^{-5.7}) and observations do not even rule
out that they may account for all of the baryonic dark matter in the Universe
(Omega = 10^{-1.7}). Unambiguous detections of individual IMBHs currently do
not exist, but there are observational hints from studies of microlensing
events, "ultra-luminous" X-ray sources, and centers of nearby galaxies and
globular clusters. Gravitational wave experiments will soon provide another
method to probe their existence. IMBHs have potential importance for several
fields of astrophysics and are likely to grow as a focus of research attention.


title: Large Synoptic Survey Telescope: Overview

abstract:
  A large wide-field telescope and camera with optical throughput over 200 m^2
deg^2 -- a factor of 50 beyond what we currently have -- would enable the
detection of faint moving or bursting optical objects: from Earth threatening
asteroids to energetic events at the edge of the optical universe. An optimized
design for LSST is a 8.4 m telescope with a 3 degree field of view and an
optical throughput of 260 m^2 deg^2. With its large throughput and dedicated
all-sky monitoring mode, the LSST will reach 24th magnitude in a single 10
second exposure, opening unexplored regions of astronomical parameter space.
The heart of the 2.3 Gpixel camera will be an array of imager modules with 10
micron pixels. Once each month LSST will survey up to 14,000 deg^2 of the sky
with many ~10 second exposures. Over time LSST will survey 30,000 deg^2 deeply
in multiple bandpasses, enabling innovative investigations ranging from
galactic structure to cosmology. This is a shift in paradigm for optical
astronomy: from "survey follow-up" to "survey direct science." The resulting
real-time data products and fifteen petabyte time-tagged imaging database and
photometric catalog will provide a unique resource. A collaboration of ~80
engineers and scientists is gearing up to confront this exciting challenge.


title: Detection of OH Towards the Extreme Carbon Star IRC+10216

abstract:
  We report the detection of the 1665 and 1667 MHz main lines of OH (hydroxyl)
and upper limits on the 1612 MHz satellite line of OH towards the carbon-rich
AGB star, IRC+10216. We find a beam averaged fractional abundance
x(OH)~4x10^{-8}. This detection supports the identification by Melnick et al.
(2001) of the 1_10-1_01 transition of water vapor with a 556.936 GHz emission
feature detected towards IRC+10216, since OH is the expected photodissociation
product of water vapor. The shape of the OH lines, however, differs
significantly from the shape expected based on the observations of Melnick et
al. (2001). Possible explanations for the anomalous shapes of the 1665 and 1667
MHz lines are discussed. The most likely explanations for the unexpected OH
line shapes are either masing or an asymmetric distribution of OH molecules
around IRC+10216.


title:
Magnetic Reconnection and Turbulent Mixing: From ISM to Clusters of
  Galaxies

abstract:
  Magnetic reconnection, or the ability of the magnetic field lines that are
frozen in plasma to change their topology, is a fundamental problem of
magnetohydrodynamics (MHD). We briefly examine the problem starting with the
well-known Sweet-Parker scheme, discuss effects of tearing modes, anomalous
resistivity and the concept of hyperresistivity. We show that the field
stochasticity by itself provides a way to enable fast reconnection even if, at
the scale of individual turbulent wiggles, the reconnection happens at the slow
Sweet-Parker rate. We show that fast reconnection allows efficient mixing of
magnetic field in the direction perpendicular to the local direction of
magnetic field. While the idea of stochastic reconnection still requires
numerical confirmation, our numerical simulations testify that mixing motions
perpendicular to the local magnetic field are up to high degree hydrodynamical.
This suggests that the turbulent heat transport should be similar to that in
non-magnetized turbulent fluid, namely, should have a diffusion coefficient
\sim LV_L, where V_L is the amplitude of the turbulent velocity and L is the
scale of the turbulent motions. We present numerical simulations which support
this conclusion. The application of this idea to thermal conductivity in
clusters of galaxies shows that this mechanism may dominate the diffusion of
heat and may be efficient enough to prevent cooling flow formation.


title:
Shakhbazian compact galaxy groups. II. Photometric and spectroscopic
  study of ShCG 376

abstract:
  The results of the redshift measurements and of the detailed surface
photometry in BVR of the compact group ShCG 376 are presented. The radial
velocity dispersion, the virial mass, the total luminosity, the M/L ratio, and
the crossing time of the group are estimated. The group consists of eight
accordant redshift spiral galaxies. Four (or possibly five) of the group
members have emission-line spectra. Such morphological content and the number
of emission-line galaxies are very atypical for compact galaxy groups. There
are signs of interaction between some members of the group. It is suggested
that the irregular shape of the brightest galaxy No. 4 is probably due to
interaction with other members of the group, particularly, the emission line
galaxy No. 6 with a discordant redshift (Delta v = 2600 km/s). It is speculated
that the latter galaxy may be a infalling intruder to the group.


title:
Enhanced cosmic-ray flux toward zeta Persei inferred from laboratory
  study of H3+ - e- recombination rate

abstract:
  The H3+ molecular ion plays a fundamental role in interstellar chemistry, as
it initiates a network of chemical reactions that produce many interstellar
molecules. In dense clouds, the H3+ abundance is understood using a simple
chemical model, from which observations of H3+ yield valuable estimates of
cloud path length, density, and temperature. On the other hand, observations of
diffuse clouds have suggested that H3+ is considerably more abundant than
expected from the chemical models. However, diffuse cloud models have been
hampered by the uncertain values of three key parameters: the rate of H3+
destruction by electrons, the electron fraction, and the cosmic-ray ionisation
rate. Here we report a direct experimental measurement of the H3+ destruction
rate under nearly interstellar conditions. We also report the observation of
H3+ in a diffuse cloud (towards zeta Persei) where the electron fraction is
already known. Taken together, these results allow us to derive the value of
the third uncertain model parameter: we find that the cosmic-ray ionisation
rate in this sightline is forty times faster than previously assumed. If such a
high cosmic-ray flux is indeed ubiquitous in diffuse clouds, the discrepancy
between chemical models and the previous observations of H3+ can be resolved.


title:
A Limit on the Number of Isolated Neutron Stars Detected in the ROSAT
  Bright Source Catalog

abstract:
  The challenge in searching for non-radio-pulsing isolated neutron stars
(INSs) is in excluding association with objects in the very large error boxes
(~13", 1 sigma radius) typical of sources from the largest X-ray all-sky
survey, the ROSAT All-Sky-Survey/Bright Source Catalog (RASS/BSC). We search
for candidate INSs using statistical analysis of optical (USNO-A2), infrared
(IRAS), and radio (NVSS) sources near the ROSAT X-ray localization, and show
that this selection would find 20% of the INSs in the RASS/BSC. This selection
finds 32 candidates at declinations greater than -39 deg, among which are two
previously known INSs, seventeen sources which we show are not INSs, and
thirteen the classification of which are as yet undetermined. These results
require a limit of <67 INSs (90% confidence, full sky, assuming isotropy) in
the RASS/BSC. This limit modestly constrains a naive and optimistic model for
cooling NSs in the galaxy.