title: Metals in the Neutral Interstellar Medium of Starburst Galaxies

abstract:
  Thanks to their proximity, local starbursts are perfectly suited for
high-resolution and sensitivity multiwavelength observations aimed to test our
ideas about star formation, evolution of massive stars, physics and chemical
evolution of the interstellar medium (ISM). High-resolution UV spectroscopy
with FUSE and STIS has recently given the possibility to characterize in great
detail the neutral ISM in local starbursts thanks to the presence in this
spectral range of many absorption lines from ions of the most common heavy
elements. Here we present the results for two nearby starburst galaxies, I Zw
18 and NGC 1705, and show how these results relate to the star-formation
history and evolutionary state of these stellar systems.


title:
The soft X-ray counterpart of the newly discovered INTEGRAL source
  IGRJ16195-4945

abstract:
  The INTEGRAL satellite, during its regular scanning observations of the
Galactic plane, has discovered several new X-ray sources emitting above 20 keV.
The nature of the great majority of them is still unknown. Here we report on
the likely low energy counterpart, observed with ASCA in 1994 and 1997, of one
of these sources,IGRJ16195-4945. The ASCA source is faint
(Flux~10^-11erg/cm2/s), highly absorbed (NH~10^23cm-2) and has a rather hard
spectrum (photon index$\sim$0.6).These spectral properties are suggestive of a
neutron star in a High Mass X-ray Binary. Our analysis of all the public
INTEGRAL data of IGRJ16195-4945 shows that this source is variable and was in a
high state with a 20-40 keV flux of 17mCrab in two occasions in March 2003.


title:
The iron $K_\alpha$-line as a tool for an evaluation of black hole
  parameters

abstract:
  Recent X-ray observations of microquasars and Seyfert galaxies reveal broad
emission lines in their spectra, which can arise in the innermost parts of
accretion disks. Simulations indicate that at low inclination angle the line is
measured by a distant observer as characteristic two-peak profile. However, at
high inclination angles ($> 85^0$) two additional peaks arise. This phenomenon
was discovered by Matt et al. (1993) using the Schwarzschild black hole metric
to analyze such effect. They assumed that the effect is applicable to a Kerr
metric far beyond the range of parameters that they exploited. We check and
confirm their hypothesis about such a structure of the spectral line shape for
the Kerr metric case. We use no astrophysical assumptions about the physical
structure of the emission region except the assumption that the region should
be narrow enough.
  Positions and heights of these extra peaks drastically depend on both the
radial coordinate of the emitting region (annuli) and the inclination angle. It
was found that these extra peaks arise due to gravitational lens effect in the
strong gravitational field, namely they are formed by photons with some number
of revolutions around black hole. This conclusion is based only on relativistic
calculations without any assumption about physical parameters of the accretion
disc like X-ray surface emissivity etc.
  We discuss how analysis of the iron spectral line shapes could give an
information about an upper limit of magnetic field near black hole horizon.


title:
Science Programs for a 2 m-class Telescope at Dome C, Antarctica: PILOT,
  the Pathfinder for an International Large Optical Telescope

abstract:
  The cold, dry and stable air above the summits of the Antarctic plateau
provides the best ground-based observing conditions from optical to sub-mm
wavelengths to be found on the Earth. PILOT is a proposed 2 m telescope, to be
built at Dome C in Antarctica, able to exploit these conditions for conducting
astronomy at optical and infrared wavelengths. While PILOT is intended as a
pathfinder towards the construction of future grand-design facilities, it will
also be able to undertake a range of fundamental science investigations in its
own right. This paper provides the performance specifications for PILOT,
including its instrumentation. It then describes the kinds of science projects
that it could best conduct. These range from planetary science to the search
for other solar systems, from star formation within the Galaxy to the star
formation history of the Universe, and from gravitational lensing caused by
exo-planets to that produced by the cosmic web of dark matter. PILOT would be
particularly powerful for wide-field imaging at infrared wavelengths, achieving
near-diffraction limited performance with simple tip-tilt wavefront correction.
PILOT would also be capable of near-diffraction limited performance in the
optical wavebands, as well be able to open new wavebands for regular ground
based observation; in the mid-IR from 17 to 40 microns and in the sub-mm at 200
microns.


title: Rosseland and Planck mean opacities for primordial matter

abstract:
  We present newly calculated low-temperature opacities for gas with a
primordial chemical composition. In contrast to earlier calculations which took
a pure metal-free Hydrogen/Helium mixture, we take into account the small
fractions of Deuterium and Lithium as resulting from Standard Big Bang
Nucleosynthesis. Our opacity tables cover the density range -16 < log rho [g
cm^{-3}] < -2 and temperature range of 1.8 < T [K] < 4.6, while previous tables
were usually restricted to T > 10^3 K. We find that, while the presence of
Deuterium does not significantly alter the opacity values, the presence of
Lithium gives rise to major modifications of the opacities, at some points
increasing it by approximately 2 orders of magnitude relative to pure
Hydrogen/Helium opacities.


title:
The Coronae of AB Dor and V471 Tau: Primordial angular momentum vs tidal
  spin-up

abstract:
  The zero-age main-sequence star AB Dor and the K dwarf component of the V471
Tau close binary have essentially identical rotation rates and spectral types.
An analysis of their high resolution {\it Chandra} X-ray spectra reveals
remarkably similar coronal characteristics in terms of both temperature
structure and element abundances. Both stars show depletions of low FIP
elements by factors of $\sim 3$, with higher FIP elements showing more mild
depletions. No evidence for enhancements of very low FIP ($< 7$ eV) elements,
such as Na, Al and Ca, as compared to other low FIP elements was found. The
abundance anomaly pattern for AB Dor and V471 Tau is similar to, though less
extreme than, the abundance anomalies exhibited by active RS-CVn-type binaries.
While we find statistically significant structure in the underlying
differential emission measure distributions of these stars over narrow
temperature intervals, this structure is strongly dependent on the lines used
in the analysis and is probably spurious. Based on their X-ray similarities, we
conclude that the exact evolutionary state of a star has little effect on
coronal characteristics, and that the parameters that dominate coronal
structure and composition are simply the rotation rate and spectral type.


title:
Chandra X-ray Detection of the High-Magnetic-Field Radio Pulsar PSR
  J1718-3718

abstract:
  We report on the serendipitous X-ray detection, using the Chandra X-ray
Observatory, of the radio pulsar J1718-3718. This pulsar has one of the highest
inferred surface dipole magnetic fields in the radio pulsar population (B =
7.4e13 G), higher than that inferred for one well-known Anomalous X-ray Pulsar
(AXP). The X-ray emission for J1718-3718 appears point-like and has a purely
thermal spectrum, with kT = 0.145 keV and absorbed 0.5-2 keV flux of
(6.3-6.9)e-15 erg/s/cm^2. We show that the pulsar's 2-10 keV luminosity is
several orders of magnitude smaller than those of the non-transient AXPs, and
consistent with the predictions of standard models for initial cooling. The
number of high-magnetic-field radio pulsars observed at X-ray energies now
stands at five. All are X-ray faint, suggesting that either there is a
significant physical distinction between high-magnetic-field radio pulsars and
AXPs, or that high-magnetic-field radio pulsars are, in fact, quiescent AXPs.


title:
Impact of LISA's low frequency sensitivity on observations of massive
  black hole mergers

abstract:
  LISA will be able to detect gravitational waves from inspiralling massive
black hole (MBH) binaries out to redshifts z > 10. If the binary masses and
luminosity distances can be extracted from the LISA data stream, this
information can be used to reveal the merger history of MBH binaries and their
host galaxies in the evolving universe. Since this parameter extraction
generally requires that LISA observe the inspiral for a significant fraction of
its yearly orbit, carrying out this program requires adequate sensitivity at
low frequencies, f < 10^{-4} Hz. Using several candidate low frequency
sensitivities, we examine LISA's potential for characterizing MBH binary
coalescences at redshifts z > 1.


title:
The Chemical Properties of Milky Way and M31 Globular Clusters: II.
  Stellar Population Model Predictions

abstract:
  We derive ages, metallicities and [alpha/Fe] ratios from the integrated
spectra of 23 globular clusters in M31, by employing multivariate fits to two
stellar population models. In parallel we analyze spectra of 21 Galactic
globular clusters in order to facilitate a differential analysis. We find that
the M31 globular clusters separate into three distinct components in age and
metallicity. We identify an old, metal-poor group (7 clusters), an old,
metal-rich group (10 clusters) and an intermediate age (3-6 Gyr),
intermediate-metallicity ([Z/H]~-1) group (6 clusters). This third group is not
identified in the Galactic globular cluster sample. The majority of globular
clusters in both samples appear to be enhanced in alpha-elements, the degree of
enhancement being model-dependent. The intermediate age GCs appear to be the
most enhanced, with [alpha/Fe]~0.4. These clusters are clearly depressed in CN
with respect to the models and the bulk of the M31 and Milky Way sample.
Compared to the bulge of M31, M32 and NGC 205, these clusters most resemble the
stellar populations in NGC 205 in terms of age, metallicity and CN abundance.
We infer horizontal branch morphologies for the M31 clusters using the Rose
(1984) Ca II index, and demonstrate that blue horizontal branches are not
leading to erroneous age estimates in our analysis. The intermediate age
clusters have generally higher velocities than the bulk of the M31 cluster
population. Spatially, three of these clusters are projected onto the bulge
region, the remaining three are distributed at large radii. We discuss these
objects within the context of the build-up of the M31 halo, and suggest that
these clusters possibly originated in a gas-rich dwarf galaxy, which may or may
not be presently observable in M31.


title: Population synthesis as a probe of neutron star thermal evolution

abstract:
  The study of thermal emission from isolated, cooling neutron stars plays a
key role in probing the physical conditions of both the star crust and the
core. The comparison of theoretical models for the star thermal evolution with
the surface temperature derived from X-ray observations of sources of different
age is one of the main tools to investigate the properties of the interior and
constrain the equation of state. Here we propose to use population synthesis
studies as an independent approach to test the physics governing the star
cooling. Theoretical Log N - Log S distributions depend on the assumed neutron
star thermal evolution. We have computed distributions for several different
cooling scenarios and found that comparison with the observed Log N - Log S of
isolated neutron stars is effective in discriminating among cooling models.
Among the eleven cooling models considered in this paper, all of which may
reproduce the observed temperature vs. age diagram, only at most three can
explain the Log N - Log S distribution of close-by cooling neutron stars. The
Log N - Log S test, being a ``global'' one and despite some limitations,
appears capable of complementing the standard temperature vs. age test used up
to now.


title: Cooling of Neutron Stars with Color Superconducting Quark Cores

abstract:
  We show that within a recently developed nonlocal chiral quark model the
critical density for a phase transition to color superconducting quark matter
under neutron star conditions can be low enough for these phases to occur in
compact star configurations with masses below 1.3 M_solar. We study the cooling
of these objects in isolation for different values of the gravitational mass.
Our equation of state (EoS) allows for 2SC quark matter with a large quark gap
\~100 MeV for u and d quarks of two colors that coexists with normal quark
matter within a mixed phase in the hybrid star interior. We argue that, if the
phases with unpaired quarks were allowed, the corresponding hybrid stars would
cool too fast. If they occured for M < 1.3 M_solar, as it follows from our EoS,
one could not appropriately describe the neutron star cooling data existing by
today. We discuss a "2SC+X" phase, as a possibility to have all quarks paired
in two-flavor quark matter under neutron star constraints, where the X-gap is
of the order of 10 keV - 1 MeV. Density independent gaps do not allow to fit
the cooling data. Only the presence of an X-gap that decreases with increase of
the density could allow to appropriately fit the data in a similar compact star
mass interval to that following from a purely hadronic model. This scenario is
suggested as an alternative explanation of the cooling data in the framework of
a hybrid star model.


title:
Optically identified BL Lacertae objects from the Sloan Digital Sky
  Survey

abstract:
  We present a sample of 386 BL Lacertae (BL Lac) candidates identified from
2860 deg^2 of the Sloan Digital Sky Survey (SDSS) spectroscopic database. The
candidates are primarily selected to have quasi-featureless optical spectra and
low proper motions as measured from SDSS and USNO-B positions; however, our
ability to separate Galactic from extragalactic quasi-featureless objects
(QFOs) on the basis of proper motion alone is limited by the lack of reliable
proper motion measurements for faint objects. Fortunately, high proper motion
QFOs, mostly DC white dwarfs, populate a well defined region of color space,
approximately corresponding to blackbodies with temperatures in the range
7000-12000 K. QFOs with measurable redshifts or X-ray or radio counterparts
(i.e., evidence of an extragalactic/AGN nature) loosely follow a track in color
space that corresponds to power-law continua plus host galaxy starlight, with
typical power-law slopes in the range 1<alpha_{opt}<2 (f_{nu} propto
nu^{-alpha}). Based largely on this remarkably clean color separation, we
subdivide the sample into 240 probable candidates and 146 additional less
probable (likely stellar) candidates. The probable BL Lac candidates have
multi-wavelength properties consistent with the range of previously known BL
Lacs, with an apparent preponderance of objects with synchrotron peaks at
relatively high energies (HBL/ XBL-type). The majority of the 154 objects with
measurable redshifts have z<1, with a median of 0.45; there are also a handful
of high-redshift objects extending up to z=5.03. We identify a small number of
potential radio-quiet BL Lac candidates, although more sensitive radio
observations are needed to confirm their radio-quiet nature.


title: Outer Versus Inner Halo Globular Clusters: NGC 7492 Abundances

abstract:
  We have carried out a detailed abundance analysis for 21 elements in a sample
of four RGB stars in the outer halo globular cluster NGC 7492 (R{GC} 25 kpc);
we find [Fe/H] = -1.82 dex inferred from FeI lines (-1.79 from FeII) using high
dispersion (R=35,000) spectra obtained with HIRES at the Keck Observatory. Most
elements show no sign of star-to-star variation within our limited sample. We
have, however, detected an anti-correlation between O and Na abundances similar
to that seen in our previous analyses of inner halo GCs as well as in studies
of relatively nearby GCs by others.
  We compare the abundance ratios in NGC 7492 with those we previously
determined for the much closer old halo GCs M3 and M13. After making
corrections for trends of abundance ratio with metallicity characteristic of
halo stars, we find that for for these three GCs for each of the elements in
common we deduce identical abundance ratios with respect to Fe to within the
probable measurement uncertainties. Thus, the chemical history of the outer
halo as exemplified by the metal-poor outer halo globular cluster NGC 7492 is
indistinguishable from that of the inner halo, exemplified by M3 and M13, at
least through the epoch of formation of these old globular clusters. This
applies to the neutron capture processes as well.


title: Light Curves of Microlensed Type Ia Supernovae

abstract:
  A detailed description of the apparent light curves of microlensed SNe Ia as
extended and expanding sources is presented. We show that microlensing
amplification can have significant effects on supernova observation. A model
light curve is used to compare lensed and unlensed cases and we find that
significant changes in shape can occur because of microlensing. We briefly
discuss the probability of observing such effects as well. Throughout the paper
we consider the redshift of the source to be 1.0 and we limit our work to
spherically symmetric deflectors.


title:
Evolution of the infrared luminosity density and star formation history
  up to z~1: preliminary results from MIPS

abstract:
  Using deep observations of the Chandra Deep Field South obtained with MIPS at
24mic, we present our preliminary estimates on the evolution of the infrared
(IR) luminosity density of the Universe from z=0 to z~1. We find that a pure
density evolution of the IR luminosity function is clearly excluded by the
data. The characteristic luminosity L_IR* evolves at least by (1+z)^3.5 with
lookback time, but our monochromatic approach does not allow us to break the
degeneracy between a pure evolution in luminosity or an evolution in both
density and luminosity. Our results imply that IR luminous systems (L_IR >
10^11 L_sol) become the dominant population contributing to the comoving IR
energy density beyond z~0.5-0.6. The uncertainties affecting our measurements
are largely dominated by the poor constraints on the spectral energy
distributions that are used to translate the observed 24mic flux into
luminosities.


title:
Origin of Radio Emission from Nearby Low-Luminosity Active Galactic
  Nuclei

abstract:
  We use the observational data in radio, optical and X-ray wavebands, for a
sample of active galactic nuclei (AGNs) with measured black hole masses, to
explore the origin of radio emission from nearby low-luminosity active galactic
nuclei (LLAGNs). We find that the radio luminosities are higher than the
maximal luminosities expected from the ADAF model, for most sources in this
sample. This implies that the radio emission is dominantly from the jets in
these sources. The radio emission from a small fraction of the sources in this
sample can be explained by the ADAF model. However, comparing the observed
multi-band emission data with the spectra calculated for the ADAF or ADIOS
cases, we find that neither ADAF nor ADIOS models can reproduce the observed
multi-band emission simultaneously, with reasonable magnetic field strengths,
for these radio-weak sources. A variety of other possibilities are discussed,
and we suggest that the radio emission is probably dominated by jet emission
even in these radio-weak LLAGNs.


title:
Improved Constraints on The Neutral Intergalactic Hydrogen Surrounding
  Quasars at Redshifts z>6

abstract:
  We analyze the evolution of HII regions around the seven known SDSS quasars
at z>6. The comparison between observed and model radii of the HII regions
generated by these quasars individually, suggests that the surrounding
intergalactic hydrogen is significantly neutral. When all constraints are
combined, the existing quasar sample implies a volume averaged neutral fraction
that is larger than 10% at z>6. This limited sample permits a preliminary
analysis of the correlations between the quasar parameters, the sizes of their
HII regions, and the associated constraints on the neutral hydrogen fraction.
We find no evidence in these correlations to contradict the interpretation that
the red side of the Gunn-Peterson trough corresponds to the boundary between an
HII region and a partially neutral IGM.


title: Adaptive Mesh Refinement for Supersonic Molecular Cloud Turbulence

abstract:
  We performed a series of three-dimensional numerical simulations of
supersonic homogeneous Euler turbulence with adaptive mesh refinement (AMR) and
effective grid resolution up to 1024^3 zones. Our experiments describe
non-magnetized driven supersonic turbulent flows with an isothermal equation of
state. Mesh refinement on shocks and shear is implemented to cover dynamically
important structures with the highest resolution subgrids and calibrated to
match the turbulence statistics obtained from the equivalent uniform grid
simulations.
  We found that at a level of resolution slightly below 512^3, when a
sufficient integral/dissipation scale separation is first achieved, the
fraction of the box volume covered by the AMR subgrids first becomes smaller
than unity. At the higher AMR levels subgrids start covering smaller and
smaller fractions of the whole volume, which scale with the Reynolds number as
Re^{-1/4}. We demonstrate the consistency of this scaling with a hypothesis
that the most dynamically important structures in intermittent supersonic
turbulence are strong shocks with a fractal dimension of two. We show that
turbulence statistics derived from AMR simulations and simulations performed on
uniform grids agree surprisingly well, even though only a fraction of the
volume is covered by AMR subgrids. Based on these results, we discuss the
signature of dissipative structures in the statistical properties of supersonic
turbulence and their role in overall flow dynamics.


title:
Synchrotron Radiation From Radiatively Inefficient Accretion Flow
  Simulations: Applications to Sgr A*

abstract:
  We calculate synchrotron radiation in three-dimensional pseudo-Newtonian
magnetohydrodynamic simulations of radiatively inefficient accretion flows. We
show that the emission is highly variable at optically thin frequencies, with
order of magnitude variability on time-scales as short as the orbital period
near the last stable orbit; this emission is linearly polarized at the 20-50 %
level due to the coherent toroidal magnetic field in the flow. At optically
thick frequencies, both the variability amplitude and polarization fraction
decrease significantly with decreasing photon frequency. We argue that these
results are broadly consistent with the observed properties of Sgr A* at the
Galactic Center, including the rapid infrared flaring.


title: A radio study of the superwind galaxy NGC1482

abstract:
  We present multifrequency radio continuum as well as HI observations of the
superwind galaxy NGC1482, with both the GMRT and the VLA. This galaxy has a
remarkable hourglass-shaped optical emission line outflow as well as bi-polar
soft X-ray bubbles on opposite sides of the galactic disk. The low-frequency,
lower-resolution radio observations show a smooth structure. From the
non-thermal emission, we estimate the available energy in supernovae, and
examine whether this would be adequate to drive the observed superwind outflow.
The high-frequency, high-resolution radio images of the central starburst
region located at the base of the superwind bi-cone shows one prominent peak
and more extended emission with substructure. This image has been compared with
the infrared, optical red-continuum, H_alpha, and, soft and hard X-ray images
from Chandra. The peak of infrared emission is the only feature which is
coincident with the prominent radio peak, and possibly defines the centre of
the galaxy. The HI observations with the GMRT show two blobs of emission on
opposite sides of the central region. These are rotating about the centre of
the galaxy and are located at ~2.4 kpc from it. In addition, these observations
also reveal a multicomponent HI-absorption profile against the central region
of the radio source, with a total width of ~250 km/s. The extreme blue- and
red-shifted absorption components are at 1688 and 1942 km/s respectively, while
the peak absorption is at 1836 km/s. This is consistent with the heliocentric
systemic velocity of 1850+/-20 km/s, estimated from a variety of observations.
We discuss possible implications of these results.


title: From Edelweiss-I to Edelweiss-II

abstract:
  The EDELWEISS experiment is a Direct Dark Matter search using 320 g
heat-and-ionization Ge cryogenic detectors. The final results obtained by the
EDELWEISS-I stage corresponding to a total of 62 kg.day are presented. The
status of EDELWEISS-II, involving in a first phase ~10 kg of detecors and
aiming to gain two orders of magnitude in sensitivity, is also described.


title:
"Expansion" around the vacuum equation of state - sudden future
  singularities and asymptotic behavior

abstract:
  The dark energy model with the equation of state p_d=-rho_d - A rho_d^alpha
is studied. The model comprises and provides realization of several types of
singularities in different parameter regimes: the divergence of the dark energy
density and pressure at finite time and finite value of the scale factor, the
singularity of the "big rip" type and the sudden future singularity recently
introduced by Barrow. For parameter choices which lead to a nonsingular
expansion of the universe, various types of the asymptotic evolution are found.
The entire time evolution of the universe is described both analytically and
numerically. The advantages of this dark energy EOS as a parametrization of
dark energy are discussed.


title:
Space telescope Imaging Spectrograph ultraviolet spectra of LMC
  planetary nebulae. A study of carbon abundances and stellar evolution

abstract:
  We acquired spectra of 24 LMC PNe in the 1150--3000 \AA range in order to
determine carbon and other ionic abundances. The sample more than doubles the
number of LMC PNe with good quality UV spectra in this wavelength range, and
whose optical images are available in the {\it HST} archive. The {\it Space
Telescope Imaging Spectrograph} was used with a very large aperture to obtain
virtually slit-less spectra, thus the monochromatic images in the major nebulae
emission lines are also available. The analysis of the data shows extremely
good quality spectra. This paper presents the emission lines identified and
measured, and the calculation of the ionic abundances of the emitting carbon
and other ions, and total carbon abundance. P-Cygni profiles have been found in
a fraction of the nebulae, and the limiting velocities of the stellar winds
estimated. The total carbon abundance can be inferred reliably in most nebulae.
We found that the average carbon abundance in round and elliptical PNe is one
order of magnitude larger than that of the bipolar PNe, while elliptical and
round PNe with a bipolar core have a bimodal behavior. This results confirm
that bipolarity in LMC PNe is tightly correlated with high mass progenitors.
When compared to predicted yields, we found that the observed abundance ratio
show a shift toward higher carbon abundances, that may be due to initial
conditions assumed in the models not appropriate for LMC PNe.


title: Evolution of AGN - an optical view

abstract:
  This article discusses the our changing knowledge of the evolution of AGN
from an optical perspective. It focusses on optically-unobscured (type-1) AGN
as it is much trickier to investigate the evolution type-2 objects from an
optical point of view. It discusses major optical survey work that improved our
knowledge of QSO evolution during the last five years. It touches on the shape
of the QSO luminosity function, on the peak of QSO activity, the quest for
reddened QSOs and spectral evolution. Finally, it summarizes recent advances in
the research of host galaxies, which probably hold the key for the triggering
mechanisms of the activity, and reiterates the difficulty of understanding the
physical evolution of AGN and its place in the context of galaxy evolution.


title:
The CMB temperature power spectrum from an improved analysis of the
  Archeops data

abstract:
  We present improved results on the measurement of the angular power spectrum
of the Cosmic Microwave Background (CMB) temperature anisotropies using the
data from the last Archeops flight. This refined analysis is obtained by using
the 6 most sensitive photometric pixels in the CMB bands centered at 143 and
217 GHz and 20% of the sky, mostly clear of foregrounds. Using two different
cross-correlation methods, we obtain very similar results for the angular power
spectrum. Consistency checks are performed to test the robustness of these
results paying particular attention to the foreground contamination level which
remains well below the statistical uncertainties. The multipole range from l=10
to l=700 is covered with 25 bins, confirming strong evidence for a plateau at
large angular scales (the Sachs-Wolfe plateau) followed by two acoustic peaks
centered around l=220 and l=550 respectively. These data provide an independent
confirmation, obtained at different frequencies, of the WMAP first year
results.


title:
The influence of the geomagnetic field and of the uncertainties in the
  primary spectrum on the development of the muon flux in the atmosphere

abstract:
  In this paper we study the sensitivity of the flux of atmospheric muons to
uncertainties in the primary cosmic ray spectrum and to the treatment of the
geomagnetic field in a calculation. We use the air shower simulation program
AIRES to make the calculation for two different primary spectra and under
several approximations to the propagation of charged particles in the
geomagnetic field. The results illustrate the importance of accurate modelling
of the geomagnetic field effects. We propose a high and a low fit of the proton
and helium fluxes, and calculate the muon fluxes with these different inputs.
Comparison with measurements of the muon flux by the CAPRICE experiment shows a
slight preference for the higher primary cosmic ray flux parametrization.


title:
Chemical Evolution of Late-type Dwarf Galaxies - The windy starburst
  dwarfs NGC 1569 and NGC 1705

abstract:
  Thanks to the capabilities of modern telescopes and instrumentation, it is
now possible to resolve single stars in external dwarf galaxies, provided they
are bright enough. For galactic regions with deep enough photometry, detailed
colour-magnitude diagrams are constructed, from which the star formation
history and the initial mass function can be inferred by comparison with
synthetic diagrams. Both the star formation history and the initial mass
function are free parameters of galactic chemical evolution models. In this
contribution we show how constraining them through high resolution photometry
in principle allows us to better understand the mechanisms of dwarf galaxy
formation and evolution.


title:
Direct evidence of the receding `torus' around central nuclei of
  powerful radio sources

abstract:
  The presence of obscuring material (or a dusty `torus') in active galactic
nuclei (AGN) is central to the unification model for AGN. Two models, the
multi-population model for radio sources and the receding torus model, are
capable of describing observational properties of powerful radio galaxies and
radio quasars. Here, I study the changes of the opening angle of the obscuring
torus with radio luminosity at 151 MHz, [O III] emission-line luminosity and
cosmic epoch aiming to discriminate between two working models. An analytical
expression relating the half opening angle of the torus to the mean projected
linear sizes of double radio galaxies and quasars is derived. The sizes of
powerful double radio sources taken from the combined sample of 3CRR, 6CE and
7CR complete samples are used to estimate the torus opening angle. I found a
statistically significant correlation between the half opening angle of the
torus and [O III] emission-line luminosity. The opening angle increases from 20
to 60 degrees with increasing [O III] emission-line luminosity. This
correlation is interpreted as direct evidence of the receding torus around
central engines of powerful double radio sources.


title: Kinematics in the starbursting circumnuclear region of M100

abstract:
  We have obtained integral-field spectroscopic data, using the SAURON
instrument, of the bar and starbursting circumnuclear region in the barred
spiral galaxy M100. From our data we have derived kinematic maps of the mean
velocity and velocity dispersion of the stars and the gas, which we present
here. We have also produced maps of the total, [OIII], and Hbeta intensity. The
gas velocity field shows significant kinematic signatures of gas streaming
along the inner part of the bar, and of density wave streaming motions across
the miniature spiral arms in the nuclear pseudo-ring. The stellar velocity
field shows similar non-circular motions. The gas velocity dispersion is
notably smaller where the star formation occurs in the nuclear zone and HII
regions.


title:
The nearby universe observed in far-infrared and in ultraviolet: an
  analysis of the dust attenuation and the star formation activity

abstract:
  We discuss the dust attenuation and the star formation rates in the nearby
universe obtained from a comparison of far-infrared (IRAS) and ultraviolet
(GALEX) observations. The ratio of the dust to UV flux ratio is used to derive
the dust attenuation: this dust attenuation is found to increase with the
luminosity of the galaxies and from z=0 to z=1. The slope of the UV continuum
is found to be a very poor tracer of the dust attenuation in "normal" galaxies.
Galaxies selected by their UV emission are found to be rather quiescent with a
recent star formation rate equal to only 25-30% of the past averaged one.
Galaxies selected in FIR appear slightly more active in star formation.


title: Mass-to-light ratio gradients in early-type galaxy haloes

abstract:
  Since the near future should see a rapidly expanding set of probes of the
halo masses of individual early-type galaxies, we introduce a convenient
parameter for characterising the halo masses from both observational and
theoretical results: \dML, the logarithmic radial gradient of the mass-to-light
ratio. Using halo density profiles from LCDM simulations, we derive predictions
for this gradient for various galaxy luminosities and star formation
efficiencies $\epsilon_{SF}$. As a pilot study, we assemble the available \dML\
data from kinematics in early-type galaxies - representing the first unbiassed
study of halo masses in a wide range of early-type galaxy luminosities - and
find a correlation between luminosity and \dML, such that the brightest
galaxies appear the most dark-matter dominated. We find that the gradients in
most of the brightest galaxies may fit in well with the LCDM predictions, but
that there is also a population of fainter galaxies whose gradients are so low
as to imply an unreasonably high star formation efficiency $\epsilon_{SF} > 1$.
This difficulty is eased if dark haloes are not assumed to have the standard
LCDM profiles, but lower central concentrations.


title:
Discovery of a Long-Period Photometric Variation in the V361 Hya Star HS
  0702+6043

abstract:
  We report the discovery of a long-period g-mode oscillation in the previously
known short-period p-mode sdB pulsator HS 0702+6043. This makes this star an
extraordinary object, unique as a member of the family of sdB pulsators, and
one of the very few known pulsating stars overall exhibiting excited modes
along both the acoustic and gravity branches of the nonradial pulsation
spectrum. Because p-modes and g-modes probe different regions of a pulsating
star, HS 0702+6043 holds a tremendous potential for future detailed
asteroseismological investigations.


title:
Primordial Resonant Lines and Observational Strategy for ODIN and
  HERSCHEL

abstract:
  The presence of a primordial molecular or atomic medium can give us the
possibility to investigate the first phases of the structure formation. The
lines produced by resonant scattering of the CMB photons are the most important
signals coming from the dark age of the post-recombination universe. The
possibility to detect these lines with ODIN and Herschel satellites are
investigated.


title:
Ultrafast multireflector physical-optics beam simulations for the HFI
  instrument on the ESA PLANCK Surveyor

abstract:
  We present the latest results of our fast physical optics simulations of the
ESA PLANCK HFI beams. The main beams of both polarized and non-polarized
channels have been computed with account of broad frequency bands for the final
design and positions of the HFI horns. Gaussian fitting parameters of the
broadband beams have been presented. Beam polarization characteristics and horn
defocusing effects have been studied.


title: Metal Abundances in Hot DA White Dwarfs

abstract:
  We compare measured element abundances in hot DA white dwarfs from UV
observations to predictions from our self-consistent non-LTE model atmosphere
diffusion calculations.


title: Deconstructing NGC 7130

abstract:
  Observations of the Seyfert 2 and starburst galaxy NGC 7130 with the Chandra
X-ray Observatory illustrate that both of these phenomena contribute
significantly to the galaxy's detectable X-ray emission. The active galactic
nucleus (AGN) is strongly obscured, buried beneath column density N_H > 10^{24}
cm^{-2}, and it is most evident in a prominent Fe K alpha emission line with
equivalent width greater than 1 keV. The AGN accounts for most (60%) of the
observed X-rays at energy E > 2 keV, with the remainder due to spatially
extended star formation. The soft X-ray emission is strong and predominantly
thermal, on both small and large scales. We attribute the thermal emission to
stellar processes. In total, the AGN is responsible for only one-third of the
observed 0.5--10 keV luminosity of 3 x 10^{41} erg/s of this galaxy, and less
than half of its bolometric luminosity. Starburst/AGN composite galaxies like
NGC 7130 are truly common, and similar examples may contribute significantly to
the high-energy cosmic X-ray background while remaining hidden at lower
energies, especially if they are distant.


title: Elliptical galaxies from mergers of discs

abstract:
  We analyse N-body galaxy merger experiments involving disc galaxies. Mergers
of disc-bulge-halo models are compared to those of bulge-less, disc-halo models
to quantify the effects of the central bulge on the merger dynamics and on the
structure of the remnant. Our models explore galaxy mass ratios 1:1 through
3:1, and use higher bulge mass fraction than previous studies. A full
comparison of structural and dynamical properties to observations is carried
out. The presence of central bulges results in longer tidal tails, oblate final
intrinsic shapes, surface brightness profiles with higher Sersic index, steeper
rotation curves, and oblate-rotator internal dynamics. Mergers of bulge-less
galaxies do not generate long-lasting tidal tails, and their strong triaxiality
seems inconsistent with observations; these remnants show shells, which we do
not find in models including central bulges. Giant ellipticals with boxy
isophotes and anisotropic dynamics cannot be produced by the mergers modeled
here; they could be the result of mergers between lower luminosity ellipticals,
themselves plausibly formed in disc-disc mergers.


title: Internal colour gradients for E/S0 galaxies in Abell 2218

abstract:
  We determine colour gradients of $-0.15 \pm 0.08$ magnitudes per decade in
radius in F450W$-$F606W and $-0.07 \pm 0.06$ magnitudes per decade in radius in
F606W$-$F814W for a sample of 22 E/S0 galaxies in Abell 2218. These gradients
are consistent with the existence of a mild ($\sim -0.3$ dex per decade in
radius) gradient in metal abundance, (cf. previous work at lower and higher
redshift for field and cluster galaxies). The size of the observed gradients is
found to be independent of luminosity over a range spanning $M^*-1$ to
$M^*+1.5$ and also to be independent of morphological type. These results
suggest a fundamental similarity in the distributions of stellar populations in
ellipticals and the bulges of lenticular galaxies. These results are not
consistent with simple models of either monolithic collapse or hierarchical
mergers.


title: Can photo-evaporation trigger planetesimal formation?

abstract:
  We propose that UV radiation can stimulate the formation of planetesimals in
externally-illuminated protoplanetary disks. We present a numerical model of
disk evolution including vertical sedimentation and photo-evaporation by an
external O or B star. As solid material grows and settles toward the disk
midplane, the outer layers of the disk become dust depleted. When such a disk
is exposed to UV radiation, heating drives photo-evaporative mass-loss from its
surface, generating a dust-depleted outflow. The dust:gas surface density ratio
in the disk interior grows until dust in the disk midplane becomes
gravitationally unstable. Thus, UV radiation fields may induce the rapid
formation of planetesimals in disks where sedimentation has occurred.


title: Morphological evolution of disk galaxies in clusters

abstract:
  The recent discovery of hidden non-axysimmetric and disk-like structures in
bright Virgo dwarf elliptical and lenticular galaxies (dE/dSph/dS0) indicates
that they may have late-type progenitors. Using N-body simulations we follow
the evolution of disk galaxies within a LambdaCDM cluster simulated with 10e7
particles, where the hierarchical growth and galaxy harassment are modeled
self-consistently. Most of the galaxies undergo significant morphological
transformation, even at the outskirts of the cluster, and move through the
Hubble sequence from late type disks to dwarf spheroidals. None of the disks
are completely destroyed therefore they can not be the progenitors of ultra
compact dwarf galaxies (UCDs). The time evolution of the simulated galaxies is
compared with unsharp-masked images obtained from VLT data and the projected
kinematics of our models with the latest high resolution spectroscopic studies
from the Keck and Palomar telescopes.


title: The CLEF-SSH simulation project

abstract:
  The CLEF-SSH simulation project is an international collaboration, involving
the IAS, LATT and the University of Sussex, to produce large hydrodynamic
simulations of large-scale structure that implement realistic models of
radiative gas cooling and energy feedback. The objective is to use these
simulations to study the physics of galaxy clusters and to construct maps of
large angular size of the Sunyaev-Zel'dovich (SZ) effect, for the preparation
of future experiments. Here we present results from a first run, the CLEF
hydrodynamics simulation, which features 2(428)^3 particles of gas and dark
matter inside a comoving box with 200 Mpc/h on a side.


title: Clusters of Galaxies: New Results from the CLEF Hydrodynamics Simulation

abstract:
  Preliminary results are presented from the CLEF hydrodynamics simulation, a
large (N=2(428)^3 particles within a 200 Mpc/h comoving box) simulation of the
LCDM cosmology that includes both radiative cooling and a simple model for
galactic feedback. Specifically, we focus on the X-ray properties of the
simulated clusters at z=0 and demonstrate a reasonable level of agreement
between simulated and observed cluster scaling relations.


title:
Revealing the interaction between the X-ray gas of starburst galaxy UGC
  6697 and the hot intracluster medium of A1367

abstract:
  We present the result from a CHANDRA observation of an X-ray luminous
starburst galaxy UGC 6697, which is embedded in the northwest hot region of
A1367 (5 - 6 keV). A very sharp X-ray edge (~ 13 times of surface brightness
jump) at the southeast and a long tail (at least 60 kpc from the nucleus) at
the northwest of the galaxy are detected, as expected if the galaxy is moving
to the southeast. The X-ray edge, at the midway of the nucleus and the
southeast optical disk edge, is also at the same position where the Halpha
emission is truncated and a radio sharp edge is observed. The X-ray diffuse
emission is also enhanced at the southeast, implying ram pressure compression.
No extraplanar X-ray component is detected, probably due to the combining
effects of weaker outflow activity than that in nuclear starbursts, and
external confinement plus stripping. The diffuse thermal gas in UGC 6697 has a
temperature of ~ 0.7 keV and a low iron abundance (~0.1 - 0.2 solar). An X-ray
point source (L (0.5-10 keV) ~ 2.8 x 10^{40} ergs s^{-1}) is detected on the
nucleus, but not highly absorbed. Three off-center ultraluminous X-ray sources,
all with L (0.5-10 keV) > 10^{40} ergs s^{-1}, are also detected. Based on the
multi-wavelength data available, we favor that the interaction between the
interstellar medium (ISM) and the ICM plays a major role to trigger the
starburst in UGC 6697.


title:
A multi-dimensional, adiabatic, hydrodynamics code for studying tidal
  excitation

abstract:
  We have developed a parallel, simple, and fast hydrodynamics code for
multi-dimensional, self-gravitating, adiabatic flows. Our primary motivation is
the study of the non-linear evolution of white dwarf oscillations excited via
tidal resonances, typically over hundreds of stellar dynamical times.
Consequently, we require long term stability, low diffusivity, and high
algorithmic efficiency. An explicit, Eulerian, finite-difference scheme on a
regular Cartesian grid fulfills these requirements. It provides uniform
resolution throughout the flow, as well as simplifying the computation of the
self-gravitational potential, which is done via spectral methods. In this
paper, we describe the numerical scheme and present the results of some
diagnostic problems. We also demonstrate the stability of a cold white dwarf in
three dimensions over hundreds of dynamical times. Finally, we compare the
results of the numerical scheme to the linear theory of adiabatic oscillations,
finding numerical quality factors on the order of 6000, and excellent agreement
with the oscillation frequency obtained by the linear analysis.


title: Millimeter observations and modeling of the AB Aurigae system

abstract:
  (Abriged) We present the results of millimeter observations and a suitable
chemical and radiative transfer model of the AB Aur (HD 31293) circumstellar
disk and surrounding envelope. The integral molecular content of this system is
studied by observing CO, C$^{18}$O, CS, HCO$^+$, DCO$^+$, H$_2$CO, HCN, HNC,
and SiO rotational lines with the IRAM 30-m antenna, while the disk is mapped
in the HCO$^+$(1-0) transition with the Plateau de Bure interferometer. Using a
flared disk model with a vertical temperature gradient and an isothermal
spherical envelope model with a shadowed midplane and two unshielded cones
together with a gas-grain chemical network, time-dependent abundances of
observationally important molecules are calculated. Then a 2D non-LTE line
radiative transfer code is applied to compute excitation temperatures of
several rotational transitions of HCO$^+$, CO, C$^{18}$O, and CS molecules. We
synthesize the HCO$^+$(1-0) interferometric map along with single-dish CO(2-1),
C$^{18}$O(2-1), HCO$^+$(1-0), HCO$^+$(3-2), CS(2-1), and CS(5-4) spectra and
compared them with the observations. Our disk model successfully reproduces
observed interferometric HCO$^+$(1-0) data, thereby constraining the following
disk properties: (1) the inclination angle $\iota=17^{+6}_{-3}\degr$, (2) the
position angle $\phi=80\pm30\degr$, (3) the size $R_\mathrm{out}=400\pm200$ AU,
(4) the mass $M_\mathrm{disk}=1.3\cdot10^{-2} M_{\sun}$ (with a factor of
$\sim7$ uncertainty), and (5) that the disk is in Keplerian rotation.
Furthermore, indirect evidence for a local inhomogeneity of the envelope at
$\ga600$ AU is found...


title: Oscillations of Thick Accretion Discs Around Black Holes

abstract:
  We present a numerical study of the response of a thick accretion disc to a
localized, external perturbation with the aim of exciting internal modes of
oscillation. We find that the perturbations efficiently excite global modes
recently identified as acoustic p--modes, and closely related to the epicyclic
oscillations of test particles. The two strongest modes occur at
eigenfrequencies which are in a 3:2 ratio. We have assumed a constant specific
angular momentum distribution within the disc. Our models are in principle
scale--free and can be used to simulate accretion tori around stellar or super
massive black holes.


title:
Hot Jupiters and Hot Spots: The Short- and Long-term Chromospheric
  Activity on Stars with Giant Planets

abstract:
  We monitored the chromospheric activity in the Ca II H & K lines of 13
solar-type stars (including the Sun); 8 of them over three years at the CFHT
and 5 in a single run at the VLT. Ten of the 13 targets have close planetary
companions. All of the stars observed at the CFHT show long-term (months to
years) changes in H & K intensity levels. Four stars display short-term (days)
cyclical activity. For two, HD 73256 and kappa^1 Ceti, the activity is likely
associated with an active region rotating with the star, however, the flaring
in excess of the rotational modulation may be associated with a hot jupiter. A
planetary companion remains a possibility for kappa^1 Ceti. For the other two,
HD 179949 and upsilon And, the cyclic variation is synchronized to the hot
jupiter's orbit. For both stars this synchronicity with the orbit is clearly
seen in two out of three epochs. The effect is only marginal in the third epoch
at which the seasonal level of chromospheric activity had changed for both
stars. Short-term chromospheric activity appears weakly dependent on the mean
K-line reversal intensities for the sample of 13 stars. Also, a suggestive
correlation exists between this activity and the M_p sin(i) of the star's hot
jupiter. Because of their small separation (<= 0.1 AU), many of the hot
jupiters lie within the Alfv\'en radius of their host stars which allows a
direct magnetic interaction with the stellar surface. We discuss the conditions
under which a planet's magnetic field might induce activity on the stellar
surface and why no such effect was seen for the prime candidate, tau Boo. This
work opens up the possibility of characterizing planet-star interactions, with
implications for extrasolar planet magnetic fields and the energy contribution
to stellar atmospheres.


title: GRBs and the 511 keV emission of the Galactic bulge

abstract:
  We consider the phenomenology of the 511 keV emission in the Galactic bulge,
as recently observed by INTEGRAL, and propose a model is which the positrons
are produced by gamma-ray bursts (GRB) associated with mini starbursts in the
central molecular zone (CMZ). We show that the positrons can easily diffuse
across the bulge on timescales of about 10^7 yr, and that their injection rate
by GRBs is compatible with the observed fluxes if the mean time between two
GRBs in the bulge is about 8 10^4 yr x E_GRB_51. We also explain the low
disk-to-bulge emission ratio by noting that positrons from GRBs in the Galactic
disk should annihilate on timescales of < 10^4 yr in the dense shell of the
underlying supernova remnant, after the radiative transition, while the
remnants of GRBs occurring in the hot, low-density medium produced by recurrent
starbursts in the CMZ become subsonic before they can form a radiative shell,
allowing the positrons to escape and fill the whole Galactic bulge. If the mean
time between GRBs is smaller than 10^4 E_51 yr, INTEGRAL should be able to
detect the (localized) 511 keV emission associated with one or a few GRB
explosions in the disk.


title: On the width of the last scattering surface

abstract:
  We discuss the physical effects of some accelerated world models on the width
of the last scattering surface (LSS) of the cosmic microwave background
radiation (CMBR). The models considered in our analysis are X-matter (XCDM) and
a Chaplygin type gas. The redshift of the LSS does not depend on the kind of
dark energy (if XCDM of Chaplygin). Further, for a Chaplygin gas, the width of
the LSS is also only weakly dependent on the kind of scenario (if we have dark
energy plus cold dark matter or the unified picture).


title: The Structure of the Solar Core

abstract:
  Data from the Galileo mission to Jupiter and the Apollo mission to the Moon
show isotopically distinct types of xenon in Jupiter and in the Sun and
evidence of a mass separation process that selectively moves lighter elements
and the lighter isotopes of each element to the solar surface. Understanding
the source of solar luminosity, solar neutrinos, and mono-isotopic H-1 pouring
from the solar surface depends on measurements of anti-neutrinos coming from
neutron decay in the Sun and on the development of a better theoretical basis
for the empirical evidence of a.) Repulsive interactions between like nucleons;
b.) Clustering of nucleons; and c.) Neutron penetration of the gravitational
barrier surrounding a neutron star.


title: Herschel and Galaxies/AGN

abstract:
  Herschel will represent a breakthrough in the study of nearby gas-rich and
gas-poor galaxies, as it will for the first time permit imaging photometric and
spectroscopic observations of their ISM in the FIR-submm wavelength range. The
unprecedented sensitivity and angular resolution of Herschel will furthermore
yield a breakthrough in our understanding of distant galaxies and AGN, as their
gas and dust - both the ISM- and the AGN-related - will for the first time come
within reach. Herschel will undoubtedly yield major discoveries concerning the
cosmologically evolving gas and dust properties in galaxies, back to very early
epochs.


title:
Significance in gamma-ray astronomy - the Li & Ma problem in Bayesian
  statistics

abstract:
  The significance of having detected an astrophysical gamma ray source is
usually calculated by means of a formula derived by Li & Ma in 1983. We solve
the same problem in terms of Bayesian statistics, which provides a logically
more satisfactory framework. We do not use any subjective elements in the
present version of Bayesian statistics. We show that for large count numbers
and a weak source the Li & Ma formula agrees with the Bayesian result. For
other cases the two results differ, both due to the mathematically different
treatment and the fact that only Bayesian inference can take into account prior
knowldege.


title:
Transverse oscillations in solar coronal loops induced by propagating
  Alfvenic pulses

abstract:
  The propagation and the evolution of Alfvenic pulses in the solar coronal
arcades is investigated by means of MHD numerical simulations. Significant
transverse oscillations in coronal loops, triggered by nearby flare events, are
often measured in EUV lines and are generally interpreted as standing kink
modes. However, the damping times of these oscillations are typically very
short (from one to a few periods) and the physical mechanism responsible for
the decay is still a matter of debate. Moreover, the majority of the observed
cases actually appears to be better modeled by propagating, rather than
standing, modes. Here we perform 2.5-D compressible MHD simulations of
impulsively generated Alfven waves propagating in a potential magnetic arcade
(assumed as a simplified 2-D loop model), taking into account the
stratification of the solar atmosphere with height from the photosphere to the
corona. The results show a strong spreading of the initially localized pulses
along the loop, due to the variations in the Alfven velocity with height, and
correspondingly an efficient damping of the amplitude of the oscillations. We
believe that simple explanations based on the effects of wave propagation in
highly inhomogeneous media may apply to the majority of the reported cases, and
that variations of the background density and Alfven speed along the loop
should be considered as key ingredients in future models.


title:
The Opacity of Spiral Galaxy Disks III: Automating the "Synthetic Field
  Method"

abstract:
  The dust extinction in spiral disks can be estimated from the counts of
background field galaxies, provided the deleterious effects of confusion
introduced by structure in the image of the foreground spiral disk can be
calibrated. Gonzalez et al. (1998) developed a method for this calibration, the
``Synthetic Field Method'' (SFM), and applied this concept to a HST/WFPC2 image
of NGC4536. The SFM estimates the total extinction through the disk without the
necessity of assumptions about the distribution of absorbers or the disk light.
The poor statistics, however, result in a large error in individual
measurements. We report on improvements to and automation of the Synthetic
Field Method which render it suitable for application to large archival
datasets. To illustrate the strengths and weaknesses of this new method, the
results on NGC 1365, a SBb, and NGC 4536, a SABbc, are presented. The
extinction estimate for NGC1365 is A_I = 0.6 (+0.6/-0.7) at 0.45 R_25 and for
NGC4536 it is A_I = 1.6 (+1.0/-1.3) at 0.75 R_25. The results for NGC4536 are
compared with those of Gonzalez et al. (1998). The automation is found to limit
the maximum depth to which field galaxies can be found. Taking this into
account, our results agree with those of Gonzalez et al. (1998). We conclude
that this method can only give an inaccurate measure of extinction for a field
covering a small solid angle. An improved measurement of disk extinction can be
done by averaging the results over a series of HST fields, thereby improving
the statistics. This can be achieved with the automated method, trading some
completeness limit for speed. The results from this set of fields are reported
in a companion paper Holwerda et al. (2005b).


title:
The Opacity of Spiral Galaxy Disks IV: Radial Extinction Profiles from
  Counts of Distant Galaxies seen through Foreground Disks

abstract:
  Dust extinction can be determined from the number of distant field galaxies
seen through a spiral disk. To calibrate this number for the crowding and
confusion introduced by the foreground image, Gonzalez et al.(1998) and
Holwerda et al. (2005) developed the ``Synthetic Field Method'' (SFM), which
analyses synthetic fields constructed by adding various deep exposures of
unobstructed background fields to the candidate foreground galaxy field.
  The advantage of the SFM is that it gives the average opacity for area of
galaxy disk without assumptions about either the distribution of absorbers or
of the disk starlight. However it is limited by low statistics of the surviving
field galaxies, hence the need to combine a larger sample of fields. This paper
presents the first results for a sample of 32 deep HST/WFPC2 archival fields of
29 spirals.
  The radial profiles of average dust extinction in spiral galaxies based on
calibrated counts of distant field galaxies is presented here, both for
individual galaxies as well as for composites from our sample. The effects of
inclination, spiral arms and Hubble type on the radial extinction profile are
discussed. (Abbreviated)


title: The GMRT study of extremely faint dwarf irregular galaxies

abstract:
  We present results of deep, high velocity resolution ($\sim$1.6 kms$^{-1}$)
Giant Meterwave Radio Telescope (GMRT) HI 21 cm-line observations of a sample
of extremely faint (M$_B>-$12.5) dwarf irregular galaxies. Unlike previous
studies, we find large scale velocity gradients in even the faintest galaxies
of our sample i.e. their velocity fields are not "chaotic". For some of our
sample galaxies, where the velocity fields are in fact completely consistent
with ordered rotation, we derive rotation curves and determine the structure of
the dark matter halos of the galaxies from mass modeling, using the "asymmetric
drift" corrected rotation velocities. Finally, we compile from literature a
sample of galaxies with known dark matter distribution, estimated from HI
synthesis observations, and discuss the results and their implications for
hierarchical galaxy formation models.


title: Spectral structure of X-shaped radio sources

abstract:
  Analysis of Giant Metrewave Radio Telescope low frequency data for an
X-shaped source, 3C 223.1 has revealed an unusual result as discussed earlier
by Lal & Rao (2004, MNRAS in press). The radio morphologies of it at 240 and
610 MHz show a well-defined X-shaped structure with a pair of active jets along
the north-south axis and a pair of wings along the east-west axis, that pass
symmetrically through the undetected radio core. The wings (or low surface
brightness jet) seem to have flatter spectral index with respect to the high
surface brightness jet. This clearly shows the value of mapping the sample of
X-shaped sources at low frequencies. Here we present our preliminary results
for two more such sources.


title:
Hubble constant from lensing in plasma-redshift cosmology, and intrinsic
  redshift of quasars

abstract:
  In a series of articles, we have shown that the newly discovered
plasma-redshift cosmology gives a simpler, more accurate and consistent
explanation of many cosmological phenomena than the big-bang cosmology. The SNe
Ia observations are in better agreement with the magnitude-redshift relation
predicted by the plasma redshift than that predicted by the multi-parameter
big-bang cosmology. No deceleration or expansion parameters are needed. The
plasma-redshift cosmology is flat and quasi-static on a large scale. The Hubble
constant is no longer an expansion parameter, but is instead a measure of the
average electron density along the line of sight towards an object. Perusal of
the SNe Ia data and quasar data has shown that there is no time dilation. The
conventional estimates of the Hubble constant from gravitational lensing
observations use the big-bang cosmology for interpreting the observations. This
has lead to a large spread and discordant estimates of the Hubble constant. The
purpose of the present article is to show that the gravitational lensing
observations are in agreement with the plasma-redshift cosmology, and to show
how to evaluate the lensing observations based on the new plasma-redshift
cosmology. The lensing observations also indicate that the quasars have large
intrinsic redshifts.


title: The distributed burning regime in Type Ia supernova models

abstract:
  The deflagration mode of flame propagation in Type Ia supernova (SN Ia)
models requires a correct description of the interaction of the flame with
turbulent motions. It is well-known that turbulent combustion proceeds in
different regimes. For most parts of the deflagration in SNe Ia the flamelet
regime applies. This has been modeled in previous multi-dimensional
simulations. However, at late stages of the explosion, the flame will propagate
in the so-called distributed regime. We investigate the effects of this regime
on SN Ia models in a first and simplified approach and show that the trend of
effects seems capable of curing some problems of current pure deflagration
models.


title: Dissecting starburst galaxies with infrared observations

abstract:
  The infrared regime contains a number of unique diagnostic features for
probing the astrophysics of starburst galaxies. After a brief summary of the
most important tracers, we focus in detail on the use of emission lines to
probe the upper part of the main sequence in a young superstarcluster in the
Antennae, and the compact, dusty starburst in the nucleus of the nearby
ultraluminous infrared galaxy Arp220


title:
Deflections of cosmic rays in a random component of the Galactic
  magnetic field

abstract:
  We express the mean square deflections of the ultra-high energy cosmic rays
(UHECR) caused by the random component of the Galactic magnetic field (GMF) in
terms of the GMF power spectrum. We use recent measurements of the GMF spectra
in several sky patches to estimate the deflections quantitatively. We find that
deflections due to the random field constitute $0.03-0.3$ of the deflections
which are due to the regular component and depend on the direction on the sky.
They are small enough not to preclude the identification of UHECR sources, but
large enough to be detected in the new generation of UHECR experiments.


title:
Rotating massive stars: Pre-SN models and stellar yields at solar
  metallicity

abstract:
  We present a new set of stellar yields obtained from rotating stellar models
at solar metallicity covering the massive star range (9-120 solar masses). The
stellar models were calculated with the latest version of the Geneva stellar
evolution code described in Hirschi et al 2004a. The contributions from stellar
winds and from supernova explosions to the stellar yields were calculated
separately. The two contributions were then added to compute the total stellar
yields (Hirschi et al 2004b).
  The effects of rotation on pre-supernova models are significant between 15
and 30 solar masses. Above 20 solar masses, rotation may change the radius or
colour of the supernova progenitors (blue instead of red supergiant) and the
supernova type (IIb or Ib instead of II). Rotation increases the helium and CO
core sizes by a factor about 1.5. Thus, rotation increases the total metallic
yields and in particular the yields for carbon and oxygen by a factor 1.5-2.5.
  For Wolf-Rayet stars (M>30 solar masses), rotation increases the yields of
helium and other hydrogen burning products but does not significantly affect
the yields of heavy elements.


title: Challenges for Inflationary Cosmology

abstract:
  Inflationary cosmology has provided a predictive and phenomenologically very
successful scenario for early universe cosmology. Attempts to implement
inflation using scalar fields, however, lead to models with serious conceptual
problems. I will discuss some of the problems, explain why string theory could
provide solutions to a subset of these problems, and give a brief overview of
``string gas cosmology'', one of the approaches to merge string theory and
early universe cosmology.


title:
Forty eclipsing binaries in the Small Magellanic Cloud: fundamental
  parameters and Cloud distance

abstract:
  We have conducted a programme to determine the fundamental parameters of a
substantial number of eclipsing binaries of spectral types O and B in the Small
Magellanic Cloud. New spectroscopic data, obtained with the two-degree-field
multi-object spectrograph on the 3.9-m Anglo-Australian Telescope, have been
used in conjunction with photometry from the Optical Gravitational Lens
Experiment (OGLE-II) database of SMC eclipsing binaries. Previously we reported
results for 10 systems; in this second and concluding paper we present spectral
types, masses, radii, temperatures, surface gravities and luminosities for the
components of a further 40 binaries. The full sample of 50 OB-type eclipsing
systems is the largest single set of fundamental parameters determined for
high-mass binaries in any galaxy. We find that 21 of the systems studied are in
detached configurations, 28 are in semi-detached post-mass-transfer states, and
one is a contact binary.
  Each system provides a primary distance indicator. We find a mean distance
modulus to the SMC of 18.91+/-0.03+/-0.1 (internal and external uncertainties;
D=60.6+/-1.0 kpc). This value represents one of the most precise available
determinations of the distance to the SMC.


title: Illuminating Dark Energy with Cosmic Shear

abstract:
  One of the principal goals of modern cosmology is to constrain the properties
of dark energy. At present, numerous surveys are aiming to determine the
equation of state, which is assumed constant due to our poor understanding of
its behaviour (and since higher order parameterisations lead to unwieldy
errors). This raises the question - how does our "best-fit" equation of state
relate to the true function, which may vary with redshift. Saini et al. have
demonstrated that the value of w attained by a supernovae study is well
described by a weighted integral over the true function. Adopting a similar
approach, we calculate the corresponding "weight function" for a fiducial
cosmic shear survey. We disentangle contributions from the angular diameter
distance and the growth factor, finding that they partially cancel each other
out. Consequentially, the sensitivity to w at high redshift is enhanced beyond
that of supernovae studies, and is comparable, if not higher, than lensing of
the CMB. This illustrates the comlementary nature of the different techniques.
Furthermore, we find that results which would naively be interpreted as
inconsistent could arise from a time-dependent equation of state.


title: Variability Analysis: Detection and Classification

abstract:
  Gaia mission will offer an exceptional opportunity to perform variability
studies. The data homogeneity, its optimised photometric systems, composed of
11 medium and 4-5 broad bands, the high photometric precision in G band of one
milli-mag for V=13-15, the radial velocity measurements and the exquisite
astrometric precision for one billion stars will permit a detailed description
of variable objects like stars, quasars and asteroids.
  However the time sampling and the total number of measurements change from
one object to an other because of the satellite scanning law. The data analysis
is a challenge because of the huge amount of data, the complexity of the
observed objects and the peculiarities of the satellite, and needs a thorough
preparation.
  Experience can be gained by the study of past and present survey analysis and
results and Gaia should be put in perspective with the future large scale
surveys, like Pan-STARRS or LSST.
  We present the activities of the Variable Star Working Group and a general
plan to digest this unprecedented data set, focusing here on the photometry.


title:
General relativistic effects of strong magnetic fields on the
  gravitational force: a driving engine for bursts of gamma rays in SGRs?

abstract:
  In general relativity all forms of energy contribute to gravity and not only
just ordinary matter as in Newtonian Physics. This fact can be seen in the
modified hydrostatic equilibrium equation for relativistic stars pervaded by
magnetic (B) fields. It has an additional term coupled to the matter part as
well as an anisotropic term which is purely of magnetic origin. That additional
term coming from the pressure changed by the radial component of the diagonal
electromagnetic field tensor, weakens the gravitational force when B is strong
enough and can even produce an unexpected change in the attractive nature of
the force by reversing its sign. In an extreme case, this new general
relativistic (GR) effect can even trigger an instability in the star as a
consequence of the sudden reversal of the hydrostatic pressure gradient. We
suggest here that this GR effect may be the possible central engine driving the
transient giant outbursts observed in Soft Gamma-ray Repeaters (SGRs). In small
regions of the neutron star (NS), strong magnetic condensation can take place.
Beyond a critical limit, these highly magnetised bubbles may explode releasing
the trapped energy as a burst of gamma-rays of ~ 10^{36-40} erg.


title:
SiO masers in TX Cam: Simultaneous VLBA observations of two 43 GHz
  masers at four epochs

abstract:
  We present the results of simultaneous high resolution observations of v=1
and v=2, J=1-0 SiO masers toward TX Cam at four epochs covering a stellar
cycle. Near maser maximum (Epochs III and IV), the individual components of
both masers are distributed in ring-like structures but the ring is severely
disrupted near stellar maser minimum (Epochs I and II). In Epochs III and IV
there is a large overlap between the radii at which the two maser transitions
occur. However in both epochs the average radius of the v=2 maser ring is
smaller than for the v=1 maser ring, the difference being larger for Epoch IV.
The observed relative ring radii in the two transitions, and the trends on the
ring thickness, are close to those predicted by the model of Humphreys et al.
(\cite{humphreys02}). In many individual features there is an almost exact
overlap in space and velocity of emission from the two transitions, arguing
against pure radiative pumping. At both Epochs III and IV in many spectral
features only 50% of the flux density is recovered in our images, implying
significant smooth maser structure. For both transitions we find that red- and
blue-shifted masers occur in all parts of the rings, with relatively few masers
at the systemic velocity. Thus there is no evidence for rotation, although the
blue-shifted masers are somewhat more prominent to the west. At all four epochs
red-shifted components are generally brighter than blue-shifted ones. At Epochs
III and IV, we see many filamentary or spoke-like features in both v=1 and v=2
masers, especially in the red-shifted gas. These spokes show systematic
velocity gradients consistent with a decelerating outward flow with increasing
radius. We outline a possible model to explain why, given the presence of these
spokes, there is a deficit of maser features at the systemic velocity.


title:
Ultra High Energy $\nu_\tau$ Detection Using Cosmic Ray Tau Neutrino
  Telescope Used in Fluorescence/Cerenkov Light Detection

abstract:
  We have investigated the possibility of $\nu_\tau$ detection using Cosmic Ray
Tau Neutrino Telescope (CRTNT) based on air shower fluorescence/Cerenkov light
detector techniques. This approach requires an interaction of a $\nu_\tau$ with
material such as a mountain or the earth's crust. $\tau$ lepton produced in the
charged current interaction must escape from the earth and then decay and
initiate a shower in the air. The probability for the conversion from
$\nu_\tau$ to air shower has been calculated for an energy range from 1 PeV to
10 EeV. An air shower simulation program has been developed using the
simulation package Corsika. The trigger efficiency has been estimated for a
CRTNT detector similar to the HiRes/Dice detector in the shadow of Mt. Wheeler
in Nevada, USA. A rate of about 8 triggered events per year is expected for the
AGN neutrino source model with an optimized configuration and duty cycle of the
detector.


title: VLBA Imaging of Central Engines in Radio Quiet Quasars

abstract:
  We have used the Very Long Baseline Array (VLBA) to image five radio-quiet
quasars (RQQs) at milliarcsecond resolution, at frequencies between 1.4 and 5
GHz. These quasars have typical total flux densities of a few millijansky at
gigahertz frequencies, and are compact on arcsecond scales. The VLBA images
reveal that four of the quasars are dominated by unresolved radio cores, while
the fifth has an apparent two-sided jet. Typical core brightness temperatures
range from 10^8 K to at least 10^9 K. The compact radio morphologies and X-ray
luminosities of many objects in the RQQ sample seem to indicate classical
accretion onto black holes as massive as 10^9 solar masses, with emission
physics in many ways similar to their radio-loud counterparts. Therefore, the
relatively small amount of radiative energy emerging at radio wavelengths in
the RQQs may simply be due to the presence of less powerful radio jets.


title: Low-Mass Companions to Solar-Type Stars

abstract:
  We present preliminary results from a coronagraphic survey of young nearby
Sun-like stars using the Palomar and Keck adaptive optics systems. We have
targeted 251 solar analogs (F5-K5) at 20-160 pc from the Sun, spanning the
3-3000 Myr age range. The youngest (<500 Myr) 100 of these have been imaged
with deeper exposures to search for sub-stellar companions. The deep survey is
sensitive to brown-dwarf companions at separations >0.5" from their host stars,
with sensitivity extending to planetary-mass (5-15 Mjup) objects at wider (>3")
separations. Based on the discovery of a number of new low-mass (<0.2 Msun)
stellar companions, we infer that their frequency at >20 AU separations (probed
via direct imaging) may be greater (12%) than that found from radial velocity
surveys probing <4 AU separations (6%; Mazeh et al. 2003). We also report the
astrometric confirmation of the first sub-stellar companion from the survey -
an L4 brown dwarf at a projected distance of 44 AU from the 500 Myr-old star HD
49197. Based on this detection, we estimate that the frequency of sub-stellar
companions to solar-type stars is at least 1%, and possibly of order a few per
cent.


title: Spectroscopic Constants, Abundances, and Opacities of the TiH Molecule

abstract:
  Using previous measurements and quantum chemical calculations to derive the
molecular properties of the TiH molecule, we obtain new values for its
ro-vibrational constants, thermochemical data, spectral line lists, line
strengths, and absorption opacities. Furthermore, we calculate the abundance of
TiH in M and L dwarf atmospheres and conclude that it is much higher than
previously thought. We find that the TiH/TiO ratio increases strongly with
decreasing metallicity, and at high temperatures can exceed unity. We suggest
that, particularly for subdwarf L and M dwarfs, spectral features of TiH near
$\sim$0.52 \mic, 0.94 \mic, and in the $H$ band may be more easily measureable
than heretofore thought. The recent possible identification in the L subdwarf
2MASS J0532 of the 0.94 \mic feature of TiH is in keeping with this
expectation. We speculate that looking for TiH in other dwarfs and subdwarfs
will shed light on the distinctive titanium chemistry of the atmospheres of
substellar-mass objects and the dimmest stars.


title:
Survey for Galaxies Associated with z~3 Damped Lyman alpha Systems I:
  Spectroscopic Calibration of u'BVRI Photometric Selection

abstract:
  We present a survey for z~3 Lyman break galaxies (LBGs) associated with
damped Lyman alpha systems (DLAs) with the primary purpose of determining the
DLA-LBG cross-correlation. This paper describes the acquisition and analysis of
imaging and spectroscopic data of 9 quasar fields having 11 known z~3 DLAs
covering an area of 465 arcmin^2. Using deep u'BVRI images, 796 LBG candidates
to an apparent R_AB magnitude of 25.5 were photometrically selected from 17,343
sources detected in the field. Spectroscopic observations of 529 LBG candidates
using Keck LRIS yielded 339 redshifts. We have conservatively identified 211
z>2 objects with <z>=3.02+/-0.32. We discuss our method of z~3 LBG
identification and present a model of the u'BVRI photometric selection
function. We use the 339 spectra to evaluate our u'BVRI z~3 Lyman break
photometric selection technique.


title:
Influence of Primary Cosmic Radiation Mass Composition on the Estimation
  of Eas Energy

abstract:
  At the Yakutsk EAS array E_em is determined by using measurements of EAS
Cherenkov light flux and charged particle flux. It is known from calculations
that these characteristics depend on a sort of primary particle and, therefore,
the estimation of E_em depends on a primary particle mass. In the work the
dependence of the E_em/E_0 ratio on the energy is given and experimental data
are compared with calculations by the QGSJET model. The calculations have been
carried out for the primary proton and iron nucleus. The average calculated
meaning of the value of E_em/E_0 ratio (between the proton and iron nucleus)
within experimental errors is in agreement with experimental data that doesnt
contradict to the mixed mass composition of primary cosmic radiation.


title:
Muons with E_th >= 1 Gev and Mass Composition in the Energy Range
  10^{18}-10^{20} ev Observed by Yakutsk Eas Array

abstract:
  The ratio of the muon flux density to charged particle flux density at
distances of 300 and 600 m from the shower axis ($\rhom(300)/\rhos(300)$ and
$\rhom(600)/\rhos(600)$) is measured. In addition, the energy dependence of
$\rhom(1000)$ is analysed for showers with energies above $10^{18}$ eV. A
comparison between the experimental data and calculations performed with the
QGSJET model is given for the cases of primary proton, iron nucleus and gamma-
ray. We conclude that the showers with $\E\ge3\times10^{18}$ eV can be formed
by light nuclei with a pronounced fraction of protons and helium nuclei. It is
not excluded however that a small part of showers with energies above $10^{19}$
eV could be initiated by primary gamma-rays.


title:
Fluctuations of Xmax and Primary Particle Mass Composition in the Range
  of Energy 5 10^{17} - 3 10^{19} ev by Yakutsk Data

abstract:
  The experimental distributions of $\Xmax$ obtained with the Yakutsk EAS array
at fixed energies of $5 \times10^{17}$, $1\times10^{18}$ and $5\times10^{18}$
eV are analysed. A recent version of the QGSJET model is used as a tool of our
analysis. In the framework of this model, the most adequate mass composition of
primary particles satisfying the experimental data on $\Xmax$ is selected.


title: Cosmic Rays with Energy Above 10^{17} ev

abstract:
  The energy spectrum of primary cosmic rays with ultra high energies based on
the Yakutsk EAS Array data is presented. For the largest events values of S600
and axis coordinates have been obtained using revised lateral distribution
function. The affect of the arrival time distribution at several axis distance
on estimated density for Yakutsk and AGASA is considered.


title: On the Galactic Spiral Patterns: Stellar and Gaseous

abstract:
  The gas response to a proposed spiral stellar pattern for our Galaxy is
presented here as calculated via 2D hydrodynamic calculations utilizing the
ZEUS code in the disk plane. The locus is that found by Drimmel (2000) from
emission profiles in the K band and at 240 $\mu m$. The self-consistency of the
stellar spiral pattern was studied in previous work (see Martos et al. 2004).
It is a sensitive function of the pattern rotation speed, $\Omega_p$, among
other parameters which include the mass in the spiral and its pitch angle. Here
we further discuss the complex gaseous response found there for plausible
values of $\Omega_p$ in our Galaxy, and argue that its value must be close to
$20 km s^{-1} kpc^{-1}$ from the strong self-consistency criterion and other
recent, independent studies which depend on such parameter. However, other
values of $\Omega_p$ that have been used in the literature are explored to
study the gas response to the stellar (K band) 2-armed pattern. For our best
fit values, the gaseous response to the 2-armed pattern displayed in the K band
is a four-armed pattern with complex features in the interarm regions. This
response resembles the optical arms observed in the Milky Way and other
galaxies with the smooth underlying two-armed pattern of the old stellar disk
populations in our interpretation.


title: The Galactic Centre region

abstract:
  We have observed the central 45' region of the Galaxy at 620 MHz band of the
Giant Metrewave Radio Telescope (GMRT) in radio continuum, and measured the
polarisation properties of 64 small diameter background extragalactic sources
seen through the -6 deg < l < 6 deg, -2 deg < b < 2 deg region with the
Australia Telescope Compact Array (ATCA) and the Very Large Array (VLA). Our
620 MHz observations show that Sgr A* is located behind the HII region Sgr A
West. Using the ATCA and the VLA observations, we measured the Faraday rotation
measure (RM) of the polarised sources. The measured RMs are mostly positive,
and show no reversal of sign across the rotation axis of the Galaxy. This rules
out any circularly symmetric model of magnetic field in the region. We estimate
the magnetic field strength in the region to be ~10 microGauss, which raises
doubts against an all pervasive milliGauss field in the central few hundred pc
of the Galaxy.


title: Constraining Gravitational Theories by Observing Magnetic White Dwarfs

abstract:
  Under the assumption of a specific nonminimal coupling of torsion to Under
the assumption of a specific nonminimal coupling of torsion to
electromagnetism, spacetime is birefringent in the presence of a gravitational
field leading to depolarization of light emitted from extended astrophysical
sources. We use polarimetric data of the magnetic white dwarf RE J0317-853 to
set for the very first time constraints on the essential coupling constant for
this effect, giving k^2 <22 m^2. electromagnetism, spacetime is birefringent in
the presence of a gravitational field leading to depolarization of light
emitted from extended astrophysical sources. We use polarimetric data of the
magnetic white dwarf RE J0317-853 to set for the very first time constraints on
the essential coupling constant for this effect, giving k^2 <22 m^2.


title:
Fine-tuning in the rotation curves of spirals and the uniqueness of
  their mass modelling

abstract:
  We construct a generic mass model of a disk galaxy by combining the usual two
mass components, an exponential thin stellar disk and a dark halo for which we
alternatively assume one of the two most common mass distributions. We
construct its generic rotation curve, with two free parameters linked to its
shape and one to its amplitude, namely the halo characteristic scale lenght,
the fractional amount of Dark Matter and the total mass at one disk scale
lenght. We find that there is no need of a fine-tuning in the above parameters
to produce smooth, featureless rotation curves like the ones actually observed.
The rotation curves obtained from different mass distributions are
significanlty affected by the variation of the parameters, and show substantial
difference in their slope; however, they do not feature irregularities marking
the transition from a disk-dominated to a halo-dominated regime. On the other
hand we show, by direct analysis of a large number of plausible and different
mass models, that an observed rotation curve fulfilling well defined quality
requirements can be uniquely and properly decomposed in its dark and luminous
components; through a suitable mass modelling together with a
maximum-likelihood fitting method, in fact, the disentangling of the mass
components is accomplished with a very high resolution.


title:
Predicted chemical evolution for spiral disks from their observed
  rotation curves

abstract:
  The rotation curves for a sample of 67 spiral galaxies observed by Marquez et
al(2002) have been used as input for the multiphase chemicale volution model.
By using N[II]/Halpha as estimator of the oxygen abundance, we constraint the
possible models for each galaxy. We may, then, predict the time evolution of
these galaxies and the present time radial distribution for gas, stars and star
formation surface densities and elemental abundances.


title:
Poynting-Robertson effect and capture of grains in exterior resonances
  with planets

abstract:
  Spherical meteoroids orbiting the Sun experience orbital decay due to the
Poynting-Robertson effect and can become trapped in commensurability resonances
with a planet. Detail conditions for trapping in the planar circular restricted
three-body problem with action of solar electromagnetic radiation on spherical
grain are presented. The results are given in terms of the radiation presure
factor $\beta$.
  In general, the greater value of $\beta$, the shorter capture time in a
resonance. Captures of particles may be even several times longer than it is
presented in literature. Analytical formula for maximum capture times is given.
  Analytical theory for minimal capture eccentricities is presented. The
obtained analytical results differ from those presented in the literature.
However, the known analytical results are not very consistent with our detail
numerical computational results for $\beta-$values 0.01 and 0.05 and for the
planet Earth. Minimum eccentricities for captures into resonances are also
smaller, even in order of magnitude, than the published values.
  The presented results enable comparison with calculations for nonspherical
particles.


title:
The effect of the Galactic gas distribution on the expected cosmic rays
  spectrum

abstract:
  We will analyze the importance of varying the diffuse gas radial distribution
on the resulting expected cosmic rays spectrum. We use the recent HI density
data published by Nakanishi et al. (2004), and include them in the cosmic rays
propagation code GALPROP (Strong & Moskalenko 1998). We will obtain those
models that reproduce the characteristics shown by the cosmic rays data, and we
will then extract information about the Galaxy structure.


title: Simulation of the gamma-ray galactic distribution as seen by the AMS-2

abstract:
  In this note, we report the results of a simulation of the galactic component
of high energy gamma rays, as seen by the future AMS-02 experiment on-board the
International Space Station. The purpose of AMS is to measure the Cosmic Ray
spectra of numerous particles with unprecedented accuracy. This simulation has
been performed with the GALPROP code and its output interfaced with the AMS
Fast Simulator, to produce a sky-map of yearly counts in the AMS energy range
(over 1 GeV).


title: Dark matter distribution in the Draco dwarf from velocity moments

abstract:
  We study the distribution of dark matter in the Draco dwarf spheroidal galaxy
by modelling the moments of the line-of-sight velocity distribution of stars
obtained from new velocity data of Wilkinson et al. The luminosity distribution
is approximated by a Sersic profile fitted to the data by Odenkirchen et al. We
assume that the dark matter density profile is given by a formula with an inner
cusp and an outer exponential cut-off, as recently proposed by Kazantzidis et
al. as a result of simulations of tidal stripping of dwarfs by the potential of
the Milky Way. The dark matter distribution is characterized by the total dark
mass and the cut-off radius. The models have arbitrary velocity anisotropy
parameter assumed to be constant with radius. We estimate the three parameters
by fitting both the line-of-sight velocity dispersion and kurtosis profiles,
which allows us to break the degeneracy between the mass distribution and
velocity anisotropy. The results of the fitting procedure turn out to be very
different depending on the stellar sample considered, that is on our choice of
stars with discrepant velocities to be discarded as interlopers. For our most
reliable sample, the model parameters remain weakly constrained, but the robust
result is the preference for weakly tangential stellar orbits and high
mass-to-light ratios. The best-fitting total mass is then 7 10^7 M_sun, much
lower than recent estimates, while the mass-to-light ratio is M/L_V = 300 and
almost constant with radius. If the binary fraction in the stellar population
of Draco turns out to be significant, the kurtosis of the global velocity
distribution will be smaller and the orbits inferred will be more tangential,
while the resulting mass estimate lower.


title:
INTEGRAL discovery of persistent hard X-ray emission from the Soft Gamma
  Ray Repeater SGR 1806-20

abstract:
  We report the discovery of persistent hard X-ray emission extending up to 150
keV from the soft gamma-ray repeater SGR 1806-20 using data obtained with the
INTEGRAL satellite in 2003-2004. Previous observations of hard X-rays from
objects of this class were limited to short duration bursts and rare transient
episodes of strongly enhanced luminosity (``flares''). The emission observed
with the IBIS instrument above 20 keV has a power law spectrum with photon
index in the range 1.5-1.9 and a flux of 3 milliCrabs, corresponding to a
20-100 keV luminosity of ~10^36 erg s^-1 (for a distance of 15 kpc). The
spectral hardness and the luminosity correlate with the level of source
activity as measured from the number of emitted bursts.


title: The broad-band spectrum of the persistent emission from SGR1806-20

abstract:
  We present the results of an analysis of the quiescent X-ray emission from
the Soft Gamma-Ray Repeater SGR1806-20, taken during an INTEGRAL ultra-deep
survey of the Galactic Center region in autumn 2003. The total effective
exposure time spent on the source by the IBIS telescope during these
observations exceeded 1.5 million seconds. Combining the INTEGRAL results with
results from the XMM-Newton observatory, we present the broad band (1-200 keV)
spectrum of the quiescent emission from this source. This is the first spectrum
of the persistent emission from an SGR in the broad energy range up to 200 keV.
The luminosity of SGR1806-20 in this range was 3.6E36 ergs/s for an assumed
distance of 15 kpc. We show that weak undetected bursts should not contribute
significantly to the quiescent emission. The spectrum of the source is very
hard and has a power law shape without any trace of a high energy cutoff up to
\~160 keV. No strong cyclotron line was detected in the persistent spectrum in
the previously reported 4-6 keV band. During our next observations in the
autumn 2004 source went to active phase and its avereged flux between powerful
bursts was 2-3 times higher than in 2003. During these observations two other
SGR candidates, SGR1801-23 and SGR1808-20, were in the field of view. Neither
persistent hard X-ray emission nor bursts were detected from them. The upper
limit on the persistent flux from each of them in the energy band 18-100 keV is
about 4E-11 erg/s/cm2.


title: On the mass transfer in AE Aquarii

abstract:
  The observed properties of the close binary AE Aqr indicate that the mass
transfer in this system operates via the Roche lobe overflow mechanism, but the
material transferred from the normal companion is neither accreted onto the
surface of the white dwarf nor stored in a disk around its magnetosphere. As
previously shown, such a situation can be realized if the white dwarf operates
as a propeller. At the same time, the efficiency of the propeller action by the
white dwarf is insufficient to explain the rapid braking of the white dwarf,
which implies that the spin-down power is in excess of the bolometric
luminosity of the system. To avoid this problem we have simulated the
mass-transfer process in AE Aqr assuming that the observed braking of the white
dwarf is governed by a pulsar-like spin-down mechanism. We show that the
expected H_alpha Doppler tomogram in this case resembles the tomogram observed
from the system. We find that the agreement between the simulated and the
observed tomograms is rather good provided the mean value of the mass-transfer
rate <\dot{M}> ~5x10^16 g/s. Three spatially separated sources of H_alpha
emission can be distinguished within this approach. The structure of the
tomogram depends on the relative contributions of these sources to the H_alpha
emission and is expected to vary from night to night.


title:
The age of the Galactic thin disk from Th/Eu nucleocosmochronology I.
  Determination of [Th/Eu] abundance ratios

abstract:
  The purpose of this work is to resume investigation of Galactic thin disk
dating using nucleocosmochronology with Th/Eu stellar abundance ratios, a theme
absent from the literature since 1990. A stellar sample of 20 disk
dwarfs/subgiants of F5 to G8 spectral types with -0.8 <= [Fe/H] <= +0.3 was
selected. In stars with such spectral types and luminosity classes, spectral
synthesis techniques must be employed if we wish to achieve acceptably accurate
results. A homogeneous, self-consistent set of atmospheric parameters was
determined. Effective temperatures were determined from photometric
calibrations and H-alpha profile fitting; surface gravities were obtained from
Teff, stellar masses and luminosities; microturbulence velocities and
metallicities were obtained from detailed, differential spectroscopic analysis,
relative to the Sun, using equivalent widths of Fe I and Fe II lines. Chemical
abundances of the elements that contaminate the Th and Eu spectral regions (Ti,
V, Cr, Mn, Co, Ni, Ce, Nd, and Sm) were determined through spectroscopic
analysis. Abundance uncertainties were thoroughly scrutinised, their average
value - (0.10 +/- 0.02) dex - being found to be satisfactorily low. Eu and Th
abundances were determined by spectral synthesis of one Eu II line (4129.72 A)
and one Th II line (4019.13 A), taking into account the detailed hyperfine
structures of contaminating Co lines, as well as the hyperfine structure and
isotope shift of the Eu line. Comparison of our abundances with literature data
shows that our results exhibit a similar behaviour, but a considerably lower
scatter (36% lower for Eu, and 61% lower for Th). The [Th/Eu] abundance ratios
thus obtained were used, in the second paper of this series, to determine the
age of the Galactic disk.


title:
The age of the Galactic thin disk from Th/Eu nucleocosmochronology II.
  Chronological analysis

abstract:
  The purpose of this work is to resume investigation of Galactic thin disk
dating using nucleocosmochronology with Th/Eu stellar abundance ratios, a theme
absent from the literature since 1990. [Th/Eu] abundance ratios for a sample of
20 disk dwarfs/subgiants of F5 to G8 spectral type with -0.8 <= [Fe/H] <= +0.3,
determined in the first paper of this series, were adopted for this analysis.
We developed a Galactic chemical evolution model that includes the effect of
refuses, which are composed of stellar remnants (white dwarfs, neutron stars
and black holes) and low-mass stellar formation residues (terrestrial planets,
comets, etc.), contributing to a better fit to observational constraints. Two
Galactic disk ages were estimated, by comparing literature data on Th/Eu
production and solar abundance ratios to the model ((8.7 +5.8-4.1) Gyr), and by
comparing [Th/Eu] vs. [Fe/H] curves from the model to our stellar abundance
ratio data ((8.2 +/- 1.9) Gyr), yielding the final, average value (8.3 +/- 1.8)
Gyr. This is the first Galactic disk age determined via Th/Eu
nucleocosmochronology, and corroborates the most recent white dwarf ages
determined via cooling sequence calculations, which indicate a low age (<~ 10
Gyr) for the disk.


title: A recent rebuilding of most spirals ?

abstract:
  Re-examination of the properties of distant galaxies leads to the evidence
that most present-day spirals have built up half of their stellar masses during
the last 8 Gyr, mostly during several intense phases of star formation during
which they took the appearance of luminous infrared galaxies (LIRGs). Distant
galaxy morphologies encompass all of the expected stages of galaxy merging,
central core formation and disk growth, while their cores are much bluer than
those of present-day bulges. We have tested a spiral rebuilding scenario, for
which 75+/-25% of spirals have experienced their last major merger event less
than 8 Gyr ago. It accounts for the simultaneous decreases, during that period,
of the cosmic star formation density, of the merger rate, of the number
densities of LIRGs and of compact galaxies, while the densities of ellipticals
and large spirals are essentially unaffected.