title: Archeops: an instrument for present and future cosmology

abstract:
  Archeops is a balloon-borne instrument dedicated to measure the cosmic
microwave background (CMB) temperature anisotropies. It has, in the millimetre
domain (from 143 to 545 GHz), a high angular resolution (about 10 arcminutes)
in order to constrain high l multipoles, as well as a large sky coverage
fraction (30%) in order to minimize the cosmic variance. It has linked, before
WMAP, Cobe large angular scales to the first acoustic peak region. From its
results, inflation motivated cosmologies are reinforced with a flat Universe
(Omega_tot=1 within 3%). The dark energy density and the baryonic density are
in very good agreement with other independent estimations based on supernovae
measurements and big bang nucleosynthesis. Important results on galactic dust
emission polarization and their implications for Planck are also addressed.


title: Spatial distribution of Galactic HII regions

abstract:
  We present a new, detailed, analysis of the spatial distribution of Galactic
HII regions, exploiting a far richer database than used in previous analyses.
Galactocentric distances have been derived for 550 objects. Distances from the
Sun could be unambiguously derived from velocity data for 117 of them, lying
either outside the solar circle (84) or on a line-of-sight tangential to their
orbit (33). For 177 further sources, distance estimates are made possible by
the use of auxiliary data. A highly significant correlation between luminosity
and linear diameter was found and the corresponding least-square linear
relationship in the log-log plane was used to resolve the distance ambiguity
for an additional 256 sources. Within the solar circle the thickness of the
distribution of HII regions around the Galactic plane was found to be
comparable to that of OB stars (Bronfman et al. 2000). At larger galactocentric
radii the shape of the distribution reflects that of the warp, and its
thickness along the z axis increases with increasing distance from the Galactic
centre. We also confirm, for a much larger sample, the previously reported
positive gradient of electron temperature with galactocentric distance.


title: Kinematic Evidence for an Old Stellar Halo in the Large Magellanic Cloud

abstract:
  The oldest and most metal-poor Milky Way stars form a kinematically hot halo,
which motivates the two major formation scenarios for our galaxy: extended
hierarchical accretion and rapid collapse. RR Lyrae stars are excellent tracers
of old and metal-poor populations. We measure the kinematics of 43 RR Lyrae
stars in the inner regions of the nearby Large Magellanic Cloud (LMC) galaxy.
The velocity dispersion, \sigma_{true}=53\pm10 km/s, indicates that a
kinematically hot metal-poor old halo also exists in the LMC. This suggests
that our galaxy and smaller late-type galaxies like the LMC have similar early
formation histories.


title:
Discovery of X-ray absorption lines from the low-mass X-ray binaries 4U
  1916-053 and X 1254-069 with XMM-Newton

abstract:
  We report the discovery of narrow X-ray absorption features from the two
dipping low-mass X-ray binary 4U 1916-053 and X 1254-690 during XMM-Newton
observations. The features detected are identified with resonant scattering
absorption lines of highly ionized iron (Fe XXV and Fe XXVI). Resonant
absorption features are now observed in a growing number of low-mass X-ray
binaries (LMXBs): the two superluminal jet sources GRS 1915+105 and GRO
J1655-40, the bright LMXB GX 13+1 and the four dipping sources MXB 1658-298, X
1624-490, 4U 1916-053 and X 1254-690. The early hypothesis that their origin
could be related to the presence of superluminal jets is thus ruled out.
Ionized absorption features may be common characteristics of accreting systems.
Furthermore, their presence may depend on viewing angle, as suggested by their
detection in dippers which are viewed close to the disk plane, and by the fact
that GRS 1915+105, GRO J1655-40 and GX 13+1, although not dippers, are
suspected to be also viewed at high inclination.


title:
The far-IR spectrum of Sagittarius B2 region: Extended molecular
  absorption, photodissociation and photoionization

abstract:
  We present large scale 9'x 27'(25 pc x 70 pc) far-IR observations around Sgr
B2 using the Long-wavelength spectrometer (LWS) on board the Infrared Space
Observatory (ISO). The spectra are dominated by the strong continuum emission
of dust, the widespread molecular absorption of light hydrides (OH, CH and H2O)
and the fine structure lines of [NII], [NIII], [OIII], [CII] and [OI]. The
molecular richness in the outer layers of Sgr B2 is probed by the ISO-LWS
Fabry-Perot (35 km s^-1) detections towards Sgr B2(M), where more that 70 lines
from 15 molecular and atomic species are observed at high signal to noise
ratio.


title: High Frequency Peakers: Baby Radio Sources?

abstract:
  We present the results of second epoch simultaneous multifrequency
observations of 45 sources out of the 55 in the sample of High Frequency
Peakers (HFP) by Dallacasa et al. (2000). Seven of the stellar sources (i.e.
16% of the total number of sources and 26% of the stellar fraction) no longer
show a convex spectrum and are thus likely to be flat spectrum quasars in an
outburst phase during the first epoch of observations. The rest frame peak
frequency distribution of HFP quasars extends up to ~45 GHz while that of HFP
galaxies is confined to $\le 17$ GHz. Imaging at 1.465 GHz and 1.665 GHz has
revealed extended emission for 31% of sources, a substantially larger fraction
than found for GPS sources (~10%). In the case of HFP quasars, but not of HFP
galaxies, extended emission is associated with strong variability, consistent
with a core-jet structure.


title: High Energy Large Area Surveys: from BeppoSAX to Chandra and XMM-Newton

abstract:
  Hard X-ray observations are the most efficient way to discriminate
accretion-powered sources from star-light. Furthermore, hard X-rays are less
affected than other bands by obscuration. For these reasons the advent of
imaging instruments above 2 keV, has permitted to dramatically improve our
understanding of accretion-powered sources and their cosmic evolution. By
minimizing the problems of AGN selection and nuclear obscuration, the
combination of deep and shallow hard X-ray surveys, performed first with ASCA
and BeppoSAX and then with Chandra and XMM (e.g. ASCA LSS, HELLAS, CDFN, CDFS,
Lockman Hole, SSA13, HELLAS2XMM etc.), allows a detailed study of the evolution
of accreting sources. Somewhat surprising results are emerging: 1) the sources
making the Cosmic X-ray Background peak at a redshift (z=0.7-1) lower than soft
X-ray selected sources and lower than predicted by synthesis models for the
CXB; 2) there is strong evidence of a luminosity dependence of the evolution,
low luminosity sources (i.e. Seyfert galaxies) peaking at a significantly later
cosmic time than high luminosity sources.


title:
Analysing observed star cluster SEDs with evolutionary synthesis models:
  Systematic uncertainties

abstract:
  We discuss the systematic uncertainties inherent to analyses of observed
(broad-band) Spectral Energy Distributions (SEDs) of star clusters with
evolutionary synthesis models. We investigate the effects caused by restricting
oneself to a limited number of available passbands, choices of various passband
combinations, finite observational errors, non-continuous model input parameter
values, and restrictions in parameter space allowed during analysis. Starting
from a complete set of UBVRIJH passbands (respectively their Hubble Space
Telescope/WFPC2 equivalents) we investigate to which extent clusters with
different combinations of age, metallicity, internal extinction and mass can or
cannot be disentangled in the various evolutionary stages throughout their
lifetimes and what are the most useful passbands required to resolve the
ambiguities. We find the U and B bands to be of the highest significance, while
the V band and near-infrared data provide additional constraints. A code is
presented that makes use of luminosities of a star cluster system in all of the
possibly available passbands, and tries to find ranges of allowed
age-metallicity-extinction-mass combinations for individual members of star
cluster systems. Numerous tests and examples are presented. We show the
importance of good photometric accuracies and of determining the cluster
parameters independently without any prior assumptions.


title: The Nature of Starburst Activity in M82

abstract:
  We present new evolutionary synthesis models of M82 based mainly on
observations consisting of near-infrared integral field spectroscopy and
mid-infrared spectroscopy. The models incorporate stellar evolution, spectral
synthesis, and photoionization modeling, and are optimized for 1-45 micron
observations of starburst galaxies. The data allow us to model the starburst
regions on scales as small as 25 pc. We investigate the initial mass function
(IMF) of the stars and constrain quantitatively the spatial and temporal
evolution of starburst activity in M82. We find a typical decay timescale for
individual burst sites of a few million years. The data are consistent with the
formation of very massive stars (> 50-100 Msun) and require a flattening of the
starburst IMF below a few solar masses assuming a Salpeter slope at higher
masses. Our results are well matched by a scenario in which the global
starburst activity in M82 occurred in two successive episodes each lasting a
few million years, peaking about 10 and 5 Myr ago. The first episode took place
throughout the central regions of M82 and was particularly intense at the
nucleus while the second episode occurred predominantly in a circumnuclear ring
and along the stellar bar. We interpret this sequence as resulting from the
gravitational interaction M82 and its neighbour M81, and subsequent bar-driven
evolution. The short burst duration on all spatial scales indicates strong
negative feedback effects of starburst activity, both locally and globally.
Simple energetics considerations suggest the collective mechanical energy
released by massive stars was able to rapidly inhibit star formation after the
onset of each episode.


title: Long Period Variables in NGC 5128: II. Near-IR properties

abstract:
  Long Period Variable stars are ubiquitous among the bright red giant branch
stars in NGC 5128. Mostly they are found to be brighter than the tip of the
first ascent giant branch with magnitudes ranging from about K=19 to K=21.5.
They have periods between 155 and 1000 days and K-band amplitudes between 0.1
and 2 mag, characteristic of semi-regular and Mira variables. We compare the
colors, periods and amplitudes of these variables with those found in old
stellar populations like Galactic globular clusters and Galactic bulge as well
as with intermediate-age Magellanic Cloud long period variables. The population
of stars above the tip of the red giant branch (RGB) amounts to 2176 stars in
the outer halo field (Field 1) and 6072 stars in the inner halo field (Field
2). The comparison of the luminosity functions of the Galactic bulge, M31 bulge
and NGC 5128 halo fields shows an excess of bright AGB stars extending to M_K ~
-8.65. The large majority of these sources belong to the asymptotic giant
branch (AGB) population in NGC 5128. Subtracting the foreground Galactic stars
and probable blends, at least 26% and 70% of AGB stars are variable in Fields 1
and 2, respectively. The average period of NGC 5128 LPVs is 395 days and the
average amplitude 0.77 mag. Many more short period Miras are present in Field 2
than in Field 1 indicating a difference in the stellar populations between the
two fields. Period and amplitude distributions and near-IR colors of the
majority of LPVs in NGC 5128 are similar to the Galactic bulge variables.
However, some ~10% of LPVs have periods longer than 500 days and thus probably
more massive, hence younger, progenitor stars. A few carbon star candidates are
identified based on their red J-H and H-K colors.


title:
Continuous and Burst-like Accretion onto Substellar Companions in Mira
  Winds

abstract:
  We present numerical hydrodynamical modeling of the effects of a giant planet
or brown dwarf companion orbiting within the extended atmosphere and wind
formation zone of an approximately solar-mass Mira variable star. The
large-scale, time-dependent accretion flows within the radially oscillating and
outflowing circumstellar gas around Miras are related to Bondi-Hoyle-Lyttleton
flows, but have not, to our knowledge, been previously modelled. The new models
presented in this paper illustrate the changes in accretion and wake dynamics
as the companion mass is varied over a range from 10 to 50 Jupiter masses
($M_J$). The character of the accretion onto the companion changes greatly as
the companion mass is increased. At the lowest companion masses considered
here, a low continuous rate of mass accretion is punctuated by large, nearly
periodic bursts of accretion. When the companion mass is large, the mass
accretion has both a continuous part, and a rapidly varying, nearly stochastic
part. These trends can be understood as the result of the interplay between the
shocks and radial oscillations in the circumstellar gas, and the wake flow
behind the companion. Models with accretion bursts may produce observable
optical brightenings, and may affect SiO maser emission. (Abridged)


title:
Rebrightening of XRF 030723: further evidence for a two-component jet in
  gamma-ray burst

abstract:
  Optical afterglows from two-component jets under various configurations are
investigated numerically. Generally, the light curve is characterized by a
rapid rebrightening when the observer is off-axis with respect to the narrow
component, with the amplitude and peak time depending on detailed parameters.
We further show that the optical afterglow of XRF 030723, especially its
notable and rapid rebrightening, can be well explained by a typical
two-component jet. This X-ray flash, together with GRB 030329, strongly hints
the two-component jet model as a unified picture for X-ray flashes and
gamma-ray bursts. With a narrow but ultra-relativistic inner outflow and a wide
but less energetic outer ejecta, a two-component jet will be observed as a
typical gamma-ray burst if our line of sight is within the angular scope of the
narrow outflow. Otherwise, if the line of sight is within or slightly beyond
the cone of the wide component, an X-ray flash will be detected.


title:
Detection of Close-In Extrasolar Giant Planets Using the Fourier-Kelvin
  Stellar Interferometer

abstract:
  We evaluate the direct detection of extrasolar giant planets with a
two-aperture nulling infrared interferometer, working at angles
${\theta}<{\lambda}/2B$, and using a new `ratio-of-two-wavelengths' technique.
Simple arguments suggest that interferometric detection and characterization
should be quite possible for planets much closer than the conventional inner
working angle, or angular resolution limit. We show that the peak signal from a
nulling infrared interferometer of baseline ($\lesssim 40$ meters) will often
occur `inside the null', and that the signal variations from path-difference
fluctuations will cancel to first order in the ratio of two wavelengths. Using
a new interferometer simulation code, we evaluate the detectability of all the
known extrasolar planets as observed using this two-color method with the
proposed {\it Fourier Kelvin Stellar Interferometer (FKSI)}. In its minimum
configuration {\it FKSI} uses two 0.5-meter apertures on a 12.5-meter baseline,
and a $\pm 20^{\circ}$ field-of-regard. We predict that $\sim 7$ known
extrasolar planets are directly detectable using {\it FKSI}, with
low-resolution spectroscopy ($R \sim 20$) being possible in the most favorable
cases. Spaceborne direct detection of extrasolar giant planets is possible with
$\sim 12$ meter baselines, and does not require the much longer baselines
provided by formation flying.


title: Gravitational Waves from a Pulsar Kick Caused by Neutrino Conversions

abstract:
  It has been suggested that the observed pulsar velocities are caused by an
asymmetric neutrino emission from a hot neutron star during the first seconds
after the supernova collapse. We calculate the magnitude of gravitational waves
produced by the asymmetries in the emission of neutrinos. The resulting
periodic gravitational waves may be detectable by LIGO and LISA in the event of
a nearby supernova explosion.


title:
FUSE Measurements of Rydberg Bands of Interstellar CO between 925 and
  1150 A

abstract:
  We report the detection of 11 Rydberg bands of CO in FUSE spectra of the
sight line toward HD203374A. Eight of these electronic bands are seen in the
interstellar medium for the first time. Our simultaneous fit of five
non-Rydberg A-X bands together with the strongest Rydberg band of CO, C-X
(0-0), yields a 4-component cloud structure toward the stellar target. With
this model we synthesize the other Rydberg bands in order to derive their
oscillator strengths. We find that the strength of some bands was
underestimated in previously published results from laboratory measurements.
The implication is important for theoretical calculations of the abundance of
interstellar CO, because its dissociation and self shielding depend on
oscillator strengths for these bands.


title:
Probing the Cosmic Reionization History and Local Environment of
  Gamma-Ray Bursts through Radio Dispersion

abstract:
  We discuss the effect of dispersion delay due to intervening ionized media in
the radio emission of gamma-ray bursts (GRBs). For high redshift GRBs ($z \ga
3$), the ionized intergalactic medium (IGM) should be the dominant source of
dispersion without substantial local or foreground contamination, offering a
unique probe of the cosmic reionization epoch through measures of the free
electron column density out to different redshifts. The delay times from $z
\sim 10$ can be $\sim$ 1 hour at 100 MHz and $\sim$ 10 hours at 30 MHz. On the
other hand, dispersion by local ionized material may be important for GRBs at
lower redshifts if they occur inside or behind dense molecular clouds,
providing clues to the GRB environment; free-free absorption may also be
significant in this case. Detecting dispersion delay in the known radio
afterglow emission should be extremely challenging due to the low fluxes at the
relevant frequencies, but may be marginally possible for rare, bright
afterglows by the {\it Square Kilometer Array}. If GRBs also emit prompt,
coherent radio emission as predicted by Sagiv & Waxman (2002), the
observational prospects can be much better; detection of a sufficient sample of
high $z$ GRBs by the {\it Low Frequency Array} may allow a discrimination of
different reionization histories. Interesting constraints on the low redshift,
warm-hot IGM may also be obtainable through dispersion.


title: Velocities of RR Lyrae Stars in the Sagittarius Tidal Stream

abstract:
  We have measured radial velocities and metallicities of 16 RR Lyrae stars,
from the QUEST survey, in the Sagittarius tidal stream at 50 kpc from the
galactic center. The distribution of velocities is quite narrow (std dev=25
km/s) indicating that the structure is coherent also in velocity space. The
mean heliocentric velocity in this part of the stream is 32 km/s. The mean
metallicity of the RR Lyrae stars is [Fe/H]=-1.7. Both results are consistent
with previous studies of red giant stars in this part of the stream. The
velocities also agree with a theoretical model of the disruption of the
Sagittarius galaxy.


title: Observational Studies of Early-type Overcontact Binaries: TU Muscae

abstract:
  We present new spectroscopic and photometric data on the early-type
overcontact binary TU Muscae. The analysis of the spectroscopic data shows that
the line of sight to the system crosses three kinematically sharp and
well-separated interstellar reddening sources and that the stars rotate
synchronously. We present new radial velocities that are in good agreement with
earlier optical velocities and, thus, do not confirm the systematically smaller
velocities obtained from IUE spectra. The optical velocities are analyzed
simultaneously with the photometric data to derive accurate absolute dimesions
for the binary components.The results show that TU Mus consists of an O7.5
primary with M_1=23.5 +/- 0.8 M_sun, R_1=7.48 +/- 0.08 R_sun and an O9.5
secondary with M_2=15.3 +/- 0.4 M_sun, R_2=6.15 +/- 0.07 R_sun in an
overcontact configuration and that the orbital period has remained constant
over the three decades covered by the observations. These results might imply
that the mass transfer seen in late-type overcontact binaries does not occur in
their early-type counterparts.


title:
Stellar Orbits and the Interstellar Gas Temperature in Elliptical
  Galaxies

abstract:
  We draw attention to the close relationship between the anisotropy parameter
beta(r) for stellar orbits in elliptical galaxies and the temperature profile
T(r) of the hot interstellar gas. For nearly spherical galaxies the gas density
can be accurately determined from X-ray observations and the stellar luminosity
density can be accurately found from the optical surface brightness. The Jeans
equation and hydrostatic equilibrium establish a connection between beta(r) and
T(r) that must be consistent with the observed stellar velocity dispersion.
Purely optical observations of the bright elliptical galaxy NGC 4472 indicate
beta(r) < 0.35 within the effective radius. However, the X-ray gas temperature
profile T(r) for NGC 4472 requires significantly larger anisotropy, beta = 0.6
- 0.7, about twice the optical value. This strong preference for radial stellar
orbits must be understood in terms of the formation history of massive
elliptical galaxies. Conversely, if the smaller, optically determined
anisotropy is indeed correct, we are led to the important conclusion that the
temperature profile T(r) of the hot interstellar gas in NGC 4472 must differ
from that indicated by X-ray observations, or that the hot gas is not in
hydrostatic equilibrium.


title:
New Constraints on $\Omega_M$, $\Omega_\Lambda$, and w from an
  Independent Set of Eleven High-Redshift Supernovae Observed with HST

abstract:
  We report measurements of $\Omega_M$, $\Omega_\Lambda$, and w from eleven
supernovae at z=0.36-0.86 with high-quality lightcurves measured using WFPC-2
on the HST. This is an independent set of high-redshift supernovae that
confirms previous supernova evidence for an accelerating Universe. Combined
with earlier Supernova Cosmology Project data, the new supernovae yield a
flat-universe measurement of the mass density $\Omega_M=0.25^{+0.07}_{-0.06}$
(statistical) $\pm0.04$ (identified systematics), or equivalently, a
cosmological constant of $\Omega_\Lambda=0.75^{+0.06}_{-0.07}$ (statistical)
$\pm0.04$ (identified systematics). When the supernova results are combined
with independent flat-universe measurements of $\Omega_M$ from CMB and galaxy
redshift distortion data, they provide a measurement of
$w=-1.05^{+0.15}_{-0.20}$ (statistical) $\pm0.09$ (identified systematic), if w
is assumed to be constant in time. The new data offer greatly improved color
measurements of the high-redshift supernovae, and hence improved host-galaxy
extinction estimates. These extinction measurements show no anomalous negative
E(B-V) at high redshift. The precision of the measurements is such that it is
possible to perform a host-galaxy extinction correction directly for individual
supernovae without any assumptions or priors on the parent E(B-V) distribution.
Our cosmological fits using full extinction corrections confirm that dark
energy is required with $P(\Omega_\Lambda>0)>0.99$, a result consistent with
previous and current supernova analyses which rely upon the identification of a
low-extinction subset or prior assumptions concerning the intrinsic extinction
distribution.


title: AGB Variables as Distance Indicators

abstract:
  Evidence for the existence of Mira Period-Luminosity relations is reviewed
including recent work on Miras with thick circumstellar shells. The calibration
of the relation at K is discussed in detail. The nature of variables deviating
from the PL relation and possible metallicity effects are also discussed.


title: The early stages of NOVA Oph 2003 (V2573 Oph)

abstract:
  Intermediate resolution spectroscopy of NOVA Oph 2003 (V2573 Oph), which was
first detected March 21th 2003 but reported July 19th} 2003, obtained 19th to
23rd of July is presented here. The photometry during the early phases of the
object is shortly discussed. We also retrieved very accurate astrometry of the
target in this crowded field. This is needed to be able to do further
observations of the post-nova during the next years. The inspection of the sky
survey plates gives a possible progenitor candidate and allows to derive a
lower limit for the outburst magnitude of about 10.0 mag. The spectrum shows an
overall expansion of 2200 km/s and has clearly complex outflow substructures.
The spectroscopy identifies this object as classical nova, "Fe II" subclass.


title: What do very nearly flat detectable cosmic topologies look like?

abstract:
  Recent studies of the detectability of cosmic topology of nearly flat
universes have often concentrated on the range of values of $\Omega_{0}$ given
by current observations. Here we study the consequences of taking the bounds on
$\Omega_{0}$ given by inflationary models, i.e. $|\Omega_0 - 1| \ll 1$. We show
that in this limit, a generic detectable non-flat manifold is locally
indistinguishable from either a cylindrical ($R^2 \times S^1$) or toroidal ($R
\times T^2$) manifold, irrespective of its global shape, with the former being
more likely. Importantly this is compatible with some recent indications based
on the analysis of high resolution CMB data. It also implies that in this limit
an observer would not be able to distinguish topologically whether the universe
is spherical, hyperbolic or flat. By severely restricting the expected
topological signatures of detectable isometries, our results provide an
effective theoretical framework for interpreting cosmological observations, and
can be used to confine any parameter space which realistic search strategies,
such as the `circles in the sky' method, need to concentrate on. This is
particularly important in the inflationary limit, where the precise nature of
cosmic topology becomes undecidable.


title:
The Star Formation Rate in disk galaxies: thresholds and dependence on
  gas amount

abstract:
  We reassess the applicability of the Toomre criterion in galactic disks and
we study the local star formation law in 16 disk galaxies for which abundance
gradients are published. The data we use consists of stellar light profiles,
atomic and molecular gas (deduced from CO with a metallicity-dependent
conversion factor), star formation rates (from H-alpha emissivities),
metallicities, dispersion velocities and rotation curves. We show that the
Toomre criterion applies successfully to the case of the Milky Way disk, but it
has limited success with the data of our sample; depending on whether the
stellar component is included or not in the stability analysis, we find average
values for the threshold ratio of the gas surface density to the critical
surface density in the range 0.5 to 0.7. We also test various star formation
laws proposed in the literature, i.e. either the simple Schmidt law or
modifications of it, that take into account dynamical factors. We find only
small differences among them as far as the overall fit to our data is
concerned; in particular, we find that all three SF laws (with parameters
derived from the fits to our data) match particularly well observations in the
Milky Way disk. In all cases we find that the exponent n of our best fit SFR
has slightly higher values than in other recent works and we suggest several
reasons that may cause that discrepancy.


title: GMRT Observations of NGC 3079

abstract:
  We present new observations at three frequencies (326 MHz, 615 MHz, and 1281
MHz) of the radio lobe spiral galaxy, NGC 3079, using the Giant Metrewave Radio
Telescope. These observations are consistent with previous data obtained at
other telescopes and reveal the structure of the nuclear radio lobes in
exquisite detail. In addition, new features are observed, some with HI
counterparts, showing broad scale radio continuum emission and extensions. The
galaxy is surrounded by a radio halo that is at least 4.8 kpc in height. Two
giant radio extensions/loops are seen on either side of the galaxy out to
$\sim$ 11 kpc from the major axis, only slightly offset from the direction of
the smaller nuclear radio lobes. If these are associated with the nuclear
outflow, then the galaxy has experienced episodic nuclear activity. Emission
along the southern major axis suggests motion through a local IGM (not yet
detected) and it may be that NGC 3079 is itself creating this local
intergalactic gas via outflows. We also present maps of the minimum energy
parameters for this galaxy, including cosmic ray energy density, electron
diffusion length, magnetic field strength, particle lifetime, and power.


title: Recombination Induced Softening and Reheating of the Cosmic Plasma

abstract:
  The atomic recombination process leads to a softening of the matter equation
of state as reflected by a reduced generalized adiabatic index, with
accompanying heat release. We study the effects of this recombination softening
and reheating of the cosmic plasma on the ionization history, visibility
function, Cold Dark Matter (CDM) transfer function, and the Cosmic Microwave
Background (CMB) spectra. The resulting modifications of the CMB spectrm is
1/10 of WMAP's current error and is comparable to PLANCK's error. Therefore,
this effect should be considered when data with higher accuracy are analysed.


title: Mass and Redshift Dependence of Dark Halo Structure

abstract:
  Using a combination of N-body simulations with different resolutions, we
study in detail how the concentrations of cold dark matter (CDM) halos depend
on halo mass at different redshifts. We confirm that halo concentrations at the
present time depend strongly on halo mass, but our results also show marked
differences from the predictions of some early empirical models. Our main
result is that the mass dependence of the concentrations becomes weaker at
higher redshifts, and at z >~ 3 halos of mass greater than 10^{11} Msun/h all
have a similar median concentration, c ~ 3.5. While the median concentrations
of low-mass halos grow significantly with time, those of massive halos change
only little with redshifts. These results are quantitatively in good agreement
with the empirical model proposed by Zhao et al. which shows that halos in the
early fast accretion phase all have similar concentrations.


title:
On stability of simplest nonsingular inflationary cosmological models
  within general relativity and gauge theories of gravity

abstract:
  In this paper we provide approximate analytical analysis of stability of
nonsingular inflationary chaotic-type cosmological models. Initial conditions
for nonsingular solutions at the bounce correspond to dominance of potential
part of the energy density of the scalar field over its kinetic part both
within general relativity and gauge theories of gravity. Moreover, scalar field
at the bounce exceeds the planckian value and on expansion stage these models
correspond to chaotic inflation. Such solutions can be well approximated by
explicitly solvable model with constant effective potential (cosmological term)
and massless scalar field during the bounce and on stages of quasi-exponential
contraction and expansion. Perturbative analysis shows that nonsingular
inflationary solutions are exponentially unstable during contraction stage.
This result is compared with numerical calculations.


title:
Hubble Space Telescope/WFPC2 Investigation of the Nuclear Morphology in
  the Toomre Sequence of Merging Galaxies

abstract:
  We report on the properties of nuclear regions in the Toomre Sequence of
merging galaxies, based on imaging data gathered with the Hubble Space
Telescope WFPC2 camera. We have imaged the 11 systems in the proposed
evolutionary merger sequence in the F555W and F814W broad-band filters, and in
H-alpha+[NII] narrow-band filters. The broad-band morphology of the nuclear
regions varies from non-nucleated starburst clumps through dust-covered nuclei
to a nucleated morphology. There is no unambiguous trend in the morphology with
merger stage. The emission-line morphology is extended beyond the nucleus in
most cases, but centrally concentrated (within 1 kpc) emission-line gas can be
seen in the four latest-stage merger systems. We have quantified the intrinsic
luminosity densities and colors within the inner 100 pc and 1 kpc of each
identified nucleus. We find little evidence for a clear trend in nuclear
properties along the merger sequence, other than a suggestive rise in the
nuclear luminosity density in the most evolved members of the sequence. The
lack of clear trends in nuclear properties is likely due both to the effects of
obscuration and geometry, as well as the physical variety of galaxies included
in the Toomre Sequence.


title: Radio Monitoring of Supernova 2001ig: The First Year

abstract:
  Supernova 2001ig in NGC 7424 has been observed with the Australia Telescope
Compact Array at ~2 week intervals since its discovery, making this the
best-studied Type IIb radio supernova since SN 1993J. We present radio light
curves for frequencies from 1.4 to 20 GHz, and preliminary attempts to model
the observed behaviour. Since peaking in radio luminosity at 8.6 and 4.8 GHz
some 1-2 months after the explosion, SN 2001ig has on at least two occasions
deviated significantly from a smooth decline, indicative of interaction with a
dense circumstellar medium and possibly of periodic progenitor mass-loss.


title: A Search for Radio-loud Quasars within the Epoch of Reionization

abstract:
  The Universe became fully reionized, and observable optically, at a time
corresponding to redshift z~6.5, so it is only by studying the HI and molecular
absorption lines against higher-redshift, radio-loud sources that one can hope
to make detailed studies of the earliest stages of galaxy formation. At present
no targets for such studies are known. In these proceedings we describe a
survey which is underway to find radio-loud quasars at z > 6.5.


title: Radio Observations of Nearby HST BL Lacs

abstract:
  We present a radio/optical study of a sample of BL Lac objects at arcsecond
and milliarcsecond resolution. The sample consists of 30 nearby (z<0.2) BL
Lacs, mostly X-ray selected. These nearby objects are weak in the radio, yet we
have successfully observed them with the VLA, VLBA and EVN, revealing
interesting morphologies. Most importantly, we find evidence of relativistic
boosting even in these low power sources (dominant core, one-sided jets). We
present a radio/optical comparison including HST observations which have
detected compact optical cores in all objects.


title:
Comment on ''On the problem of initial conditions in cosmological N-body
  simulations'' (Europhys. Lett. 57, 322)

abstract:
  In astro-ph/0109199, the initial conditions (IC's) of cosmological N-body
simulations by the Virgo Consortium are analyzed and it is concluded that the
density fluctuations are rather different from the desired ones. We have
repeated the analysis of the IC's using our own code and the code provided by
the authors of astro-ph/0109199, obtaining results that disprove the
criticisms.


title: Approaching NGC3079 with VLBI

abstract:
  The Seyfert 2 galaxy NGC3079 is one of the nearest radio-weak AGN. We have
carried out multi-frequency, multi-epoch VLBI observations of this object and
detected new components, proper motion of the order of 0.1 c, strong spectral
variability, and free-free absorption. Based on phase-referenced astrometry, we
suggest a new identification of components seen at 1.7 GHz. Our results suggest
that the nucleus in NGC3079 is embedded in a dense medium which strongly
affects the radio appearance of the AGN ejecta. We supplement our work with
Seyfert VLBI observations taken from the literature.


title:
The X-ray spectra of the flaring and quiescent states of AT Microscopii
  observed by XMM-Newton

abstract:
  The X-ray spectrum of the late-type M-dwarf binary AT Mic (dM4.5e+dM4.5e) is
observed in the wavelength range 1 - 40 Angstrom by means of rgs and epic-mos
on board XMM-Newton. During the exposure a flare occured. We have performed a
3-temperature fit and a DEM-modeling to the flaring and quiescent part of the
spectrum. We report the coronal temperature distribution, emission measures,
and abundances of the flaring and quiescent state of this bright X-ray source.
The temperature range stretches from about 1 to 60 MK. The total volume
emission measure in this temperature interval is ~12.2*10^51 cm^-3 for the
quiescent state and ~19.5*10^51 cm^-3 for the flare state. This difference is
due to the contribution of the hot temperature component. The high-resolution
spectrum of AT Mic, obtained by rgs, is dominated by the H- and He-like
transitions of C, N, O, and Ne and by Fe XVII lines, produced by the plasma
with temperatures from 1 to 10 MK. The epic-mos spectrum below 10 Angstrom
shows H- and He-like Ne, Si and the iron K-shell transitions. They are produced
by the hot component (30 MK). The iron K-shell is more prominent in the flare
state. The abundance pattern in the quiescent state of AT Mic shows the
depletion of low-FIP elements relative to high-FIP elements, indicating the
presence of an I(nverse)FIP effect in this active star. In the flare state,
however, some flattening of this IFIP effect is present.


title: A radio jet in the prototypical symbiotic star Z And?

abstract:
  As part of a multi-wavelength campaign to observe the 2000--2002 outburst of
the prototypical symbiotic star Z Andromedae, we observed this object six times
each with the Multi-Element Radio Linked Interferometer Network (MERLIN) and
Very Large Array (VLA). The radio flux varied significantly during the course
of the optical outburst at all three observation frequencies (1.4, 5, and 15
GHz). A jet-like extension was present in the 2001 September MERLIN image and
appeared to be aligned perpendicularly to the plane of the binary orbit.
Assuming that the ejection took place at the beginning of the optical outburst,
the 0.06 arcsec separation between the peak of the extended emission and the
central core implies that the ejected material was moving with a velocity of
\~400 km/s. This extended emission faded on a timescale of ~months and was not
detected at any other epoch. We consider the implications of jets being a
component of a ``prototypical'' symbiotic system and compare properties of the
observed jet of Z And with those of the jets in X-ray binary systems.


title: Where has all the polarization gone?

abstract:
  We have observed the five radio galaxies NGC1052, NGC4261, Hydra A, Centaurus
A and Cygnus A with polarimetric VLBI at 15 GHz to look for possible Faraday
rotation in foreground absorbers. Only Cygnus A was found to be polarized at
the level of 0.4 %, the other four objects were found to be unpolarized (<0.3
%). We discuss implications for magnetic field structures and physical
conditions in the absorbers imposed by the absence of polarized emission at
this high frequency.


title: Remarks about the thermodynamic limit in selfgravitating systems

abstract:
  The present effort addresses the question about the existence of a
well-defined thermodynamic limit for the astrophysical systems with the
following power law form: to tend the number of particles, N, the total energy,
E, and the characteristic linear dimension of the system, L, to infinity,
keeping constant E/N^{\Lambda_{E}} and L/N^{\Lambda_{L}}, being \Lambda_{E} and
\Lambda_{L} certain scaling exponent constant. This study is carried out for a
system constituted by a non-rotating fluid under the influence of its own
Newtonian gravitational interaction. The analysis yields that a thermodynamic
limit of the above form will only appear when the local pressure depends on the
energy density of fluid as $p=\gamma\epsilon$, being $\gamma$ certain constant.
Therefore, a thermodynamic limit with a power law form can be only satisfied by
a reduced set of models, such as the selfgravitating gas of fermions and the
Antonov isothermal model.


title:
Reply to the comment on ''On the problem of initial conditions in
  cosmological N-body simulations''

abstract:
  We reply to some comments in astro-ph/0309381 concerning the problem of
setting-up initial conditions in cosmological N-body simulations


title: GOLD Mine: A new Galaxy Database on the WEB

abstract:
  The galaxy database "GOLDmine" (http://goldmine.mib.infn.it/) has been
significantly updated (Sept/1/2003)
  The new features include: a) Sample extension:the GOLDmine sample has been
extended from the original Virgo cluster + Coma supercluster regions to include
the clusters: A262, Cancer, A2147, A2151, A2197, A2199. 382 galaxies from the
GCGC (with m_p<15.7) have been added in these regions. b) New query keys: 1)
query by near position (and near name). 2) query by available images. c)
Routinary image update: 1) 59 (B). 72 (V) and 70 (H_alpha) new frames from
observations carried on by the GOLDmine team in spring 2003. 2) 157 new optical
(drift-scan) spectra from observations carried on by the GOLDmine team in
2002-2003. 3) 225 B frames of VCC galaxies taken with the INT (kindly provided
by S. Sabatini). 4) 56 B frames of galaxies in A1367 taken with the CFHT
(kindly provided by M. Treyer). 5) 20 (H), 32 (K) band frames of bright Virgo
members (from 2MASS). The new numbers in GOLDmine are: 3649 galaxies, 706
V-band frames, 858 B-band frames, 385 H_alpha frames (NET), 385 H_alpha frames
(OFF-band), 1241 H-band frames, 114 K-band frames, 323 Spectra All frames are
available in FITS (and jpg) format.


title: Charges and Magnetic Fields of the Slowly-rotating Neutron Stars

abstract:
  In association with the Goldreich-Julian's magnetic braking mechanism to
explain the luminosity of radio pulsars as a result of their spin-down, it is
of some interest to explore how much of magnetic flux can actually penetrate
the surface of the rotating neutron stars at least in idealized situations. In
order to address this issue, one needs to figure out the amount of charge on
and the structure of magnetic field around a rotating neutron star. In the
present work, based on the solution-generating method given by Wald, the
magnetic fields around both the uncharged and (slightly) charged neutron star
have been obtained. Particularly for the charged neutron star, it has been
demonstrated following again the argument by Wald that the neutron star will
gradually accrete the charge until it reaches the equilibrium value
$\tilde{Q}=2B_{0}J$. Then next, the magnetic flux through one half of the
surface of the rotating neutron star has been computed as well. With the
nonvanishing accretion charge having value in the range $0 < \tilde{Q} \leq
2B_{0}J$, the total magnetic flux through the neutron star has been shown to be
greater than that without the accretion charge.


title:
Tight Cosmological Constraints from the Angular-Size/Redshift Relation
  for Ultra-Compact Radio Sources

abstract:
  Some years ago (Jackson and Dodgson 1997) analysis of the
angular-size/redshift relationship for ultra-compact radio sources indicted
that for spatially flat universes the best choice of cosmological parameters
was Omega_m=0.2 and Omega_Lambda=0.8. Here I present an astrophysical model of
these sources, based upon the idea that for those with redshift z>0.5 each
measured angular size corresponds to a single compact component which is moving
relativistically towards the observer; this model gives a reasonable account of
their behaviour as standard measuring rods. A new analysis of the original data
set (Gurvits 1994), taking into account possible selection effects which bias
against large objects, gives Omega_m=0.24+0.09/-0.07 for flat universes. The
data points match the corresponding theoretical curve very accurately out to
z~3, and there is clear and sustained indication of the switch from
acceleration to deceleration, which occurs at z=0.85.


title: Joint VLTI/VLBA observations of Mira stars

abstract:
  We present preliminary results on a recently started project to perform
coordinated observations of Mira stars using near-infrared and radio
long-baseline interferometry. We concentrate on recent observations of the Mira
star S Ori. Observations with the ESO Very Large Telescope Interferometer
(VLTI) were performed to measure the near-infrared diameter of the stellar
surface. Concurrent VLBA observations of SiO maser emission towards this Mira
star were performed to probe the structure and dynamics of the circumstellar
atmosphere. Our near-infrared measurements suggest a diameter change consistent
with the photometric period. The SiO maser emission appears to be at a distance
of $\sim$ 2 stellar radii ($\Theta_{\rm UD} \sim$ 10.7 mas, $\Theta_{\rm SiO}
\sim$ 20 mas, both at stellar phase $\sim$ 0.7), and to show a clumpy
distribution within a ring-like structure.


title: VLBA Calibrator Survey: Astrometric and Image Results

abstract:
  Positions and maps of 1608 new compact sources were obtained in twelve
sessions observed during 1994--2002 at the VLBA network at 8.4/2.3 GHz. These
sources are recommended for use as calibrators for phase reference imaging and
as geodetic sources for astrometric/geodetic VLBI applications.


title: Contribution of the VLBA Network to Geodynamics

abstract:
  A decade of observations in geodetic mode with the VLBA network gave valuable
results. Approximately 1/5 of all geodetic observations are recorded in VLBA
mode and processed at the Socorro correlator. Ten years of observations allowed
us to reliably measure slow intra-plate motion of the VLBA stations located on
the North-American plate. It also helped us to achieve scientific objectives of
geodetic programs: verify models of harmonic and anharmonic site position
variations caused by various loadings, improve models of core-mantle boundary,
investigate mantle rheology and solve other tasks.


title:
An X-ray Baldwin effect for the narrow Fe K-alpha lines observed in
  Active Galactic Nuclei

abstract:
  The majority of Active Galactic Nuclei (AGN) observed by XMM-Newton reveal
narrow Fe K-alpha lines at ~ 6.4 keV, due to emission from cold (neutral)
material. There is an X-ray Baldwin effect in Type I AGN, in that the
equivalent width of the line decreases with increasing luminosity, with
weighted linear regression giving EW ~ L^{-0.17+/-0.08} (Spearman Rank
probability of > 99.9%). With current instrumental capabilities it is not
possible to determine the precise origin for the narrow line, with both the
Broad Line Region and putative molecular torus being possibilities. A possible
explanation for the X-ray Baldwin effect is a decrease in covering factor of
the material forming the fluorescence line.


title: MODEST: modeling stellar evolution and (hydro)dynamics

abstract:
  Simulations of dense stellar systems currently face two major hurdles, one
astrophysical and one computational. The astrophysical problem lies in the fact
that several major stages in binary evolution, such as common envelope
evolution, are still poorly understood. The best we can do in these cases is to
parametrize our ignorance, in a way that is reminiscent of the introduction of
a mixing length to describe convection in a single star, or an alpha parameter
in modeling an accretion disk. The hope is that by modeling a whole star
cluster in great detail, and comparing the results to the wealth of
observational data currently available, we will be able to constrain the
parameters that capture the unknown physics. The computational problem is one
of composition: while we have accurate computer codes for modeling stellar
dynamics, stellar hydrodynamics, and stellar evolution, we currently have no
good way to put all this knowledge together in a single software environment. A
year ago, a loosely-knit organization was founded to address these problems,
MODEST for MOdeling DEnse STellar systems, with nine working groups and a
series of meetings that are held every half year. This report reviews the first
year of this initiative. Much more detail can be found on the MODEST web site
http://www.manybody.org/modest.html .


title:
Lyman alpha emission in starbursts: implications for galaxies at high
  redshift

abstract:
  We present the results of a high resolution UV 2-D spectroscopic survey of
star forming galaxies observed with HST-STIS. Our main aim was to map the Lyman
alpha profiles to learn about the gas kinematics and its relation with the
escape of Lyman alpha photons and to detect extended Lyman alpha emission due
to scattering in gaseous halos. We have combined our data with previously
obtained UV spectroscopy on other three star-forming galaxies. We find that the
P-Cygni profile is spatially extended, smooth and spans several kiloparsecs
covering a region much larger than the starburst itself. We propose a scenario
whereby an expanding super-shell is generated by the interaction of the
combined stellar winds and supernova ejecta from the young starbursts, with an
extended low density halo. The variety of observed Lyman alpha profiles both in
our sample and in high redshift starbursts is explained as phases in the time
evolution of the super-shell expanding into the disk and halo of the host
galaxy. The observed shapes, widths and velocities are in excellent agreement
with the super-shell scenario predictions and represent a time sequence. We
confirm that among the many intrinsic parameters of a star forming region that
can affect the properties of the observed Lyman alpha profiles, velocity and
density distributions of neutral gas along the line of sight are by far the
dominant ones, while the amount of dust will determine the intensity of the
emission line, if any.


title:
Systematic effects induced on IBIS detectors by background and
  inhomogeneity of the spatial response

abstract:
  The spatial distribution of the background events may affect the source
detection capability of IBIS at high energies (> 200 keV) for both ISGRI and
PICsIT layers. The observed background is found to be variable and spatially
structured, and in some cases its properties strongly deviate from the expected
statistical behaviour. Background correction methods are then necessary to
improve the quality of the shadowgrams obtained from sources. In order to
perform an efficient flat-fielding the response of the detector to both source
gamma-rays and background events is investigated using data from Monte Carlo
simulations and in-flight calibration observations.


title: Black hole binary mergers

abstract:
  I overview the current understanding of the evolution of massive black hole
(MBH) binaries in the center of the host stellar system. One of the main
questions is whether the stellar dynamical effect can make the MBH binary hard
enough that they can merge through gravitational wave radiation. So far,
theories and numerical simulations suggested otherwize, since the hardening
timescale becomes very long once "loss cone" is depleted. I'll present the
result of recent simulations on this hardening timescale, and discuss its
implication on the formation history of massive black holes.


title:
Polarization Effects in Reflecting Coronagraphs for White Light
  Applications in Astronomy

abstract:
  The properties of metal thin films have been largely overlooked in
discussions of the technical limitations and problems that arise in the field
of direct detection of exoplanets. Here, polarization properties and anisotropy
properties of highly reflecting thin metal films are examined within the
context of the requirements for the ultra-low scattered-light system
performance of coronagraphs applied to space and ground-based high-contrast,
white-light astronomy. Wavelength-dependent optical constants for highly
reflecting thin metal films, taken from the literature are used to calculate
the polarization-dependent transmissivity of a typical coronagraph. The effects
of degraded performance on the astronomical science are examined. Suggestions
are made for future work.


title: First IBIS results on the high energy emission of Cyg X-2

abstract:
  The bright low-mass X-ray binary Cyg X-2 was in the field of view of the IBIS
telescope during the early Cygnus region observations, executed during the
INTEGRAL Performance Verification Phase. The data presented are spanning about
one week and cover the rising edge of one of the two peaks of the ~ 82 day
cycle of the Cyg X-2 light curve. The IBIS data in the energy range 20-40 keV
exhibit flux variation correlated with the RXTE/ASM light curve. Two different
main exposures, separated by ~ 5 days are found to be characterized by sensibly
different spectra, with significant softening and higher X-ray luminosity in
the second part, coincident with the long-term cycle peak. At high energies,
both measured spectra are very steep. The ratio of the 30-45 keV and 20-30 keV
detected fluxes is ~ 0.30, against a value of 0.95 expected for a Crab-like
spectrum. No positive detection exists for E > 45 keV, with a flux upper limit
(5 sigma) of ~1.4E-10 erg cm-2 s-1$ in the 45-100 keV band.


title: Search for solid HDO in low-mass protostars

abstract:
  We present ground-based 2.1 to 4.2 microns observations of four low-mass
protostars. We searched for the 4.1 microns OD stretch band, characteristic of
solid HDO in grain mantles. We did not detect solid HDO in any of the four
sources, but we derive 3-sigma upper limits from 0.5% to 2% for the HDO/H2O
ratio depending on the source. These ratios provide strong constraints to
solid-state deuteration models when compared to deuterium fractionation values
observed in the gas phase. We discuss various scenarios that could lead to such
a low water deuteration compared to the high formaldehyde and methanol
deuteration observed in the gas phase.


title: First evidence of a cyclotron feature in an anomalous X-ray pulsar

abstract:
  We report on the results of the longest uninterrupted observation of the
Anomalous X-ray Pulsar 1RXS J1708-4009 obtained with the BeppoSAX satellite in
August 2001. In the phase-resolved spectrum, corresponding to the rising part
of the pulse, we found an absorption-like feature at 8.1 keV (significance
level of 4 sigma), most likely due to cyclotron resonant scattering. The
centroid energy converts to a magnetic field of 9x10^{11} G and 1.6x10^{15} G
in the case of electrons and protons, respectively. If confirmed, this would be
the first detection of a cyclotron feature in the spectrum of an anomalous
X-ray pulsar. We discuss here the results also in ligh of recent theoretical
models for these class of sources.


title: Multi-frequency & Multi-epoch VLBI study of Cygnus A

abstract:
  We present the first multi-frequency phase-referenced observations of Cygnus
A done with the VLBA at 15 and 22 GHz. We find a pronounced two-sided jet
structure, with a steep spectrum along the jet and a highly inverted spectrum
towards the counter-jet. The inverted spectrum and the frequency dependent jet
to counter-jet ratio suggest an obscuring torus in front of the counter-jet.
  From 14 epochs of 15 GHz VLBA data we accurately derive the jet and
counter-jet kinematics. For the inner jet (r <= 5 mas) we measure motions of
beta_app ~ 0.2-0.5 h^{-1} and on the counter-jet side we find beta_ app ~
0.03+-0.02 h^{-1}. We discuss the jet velocities within the unified jet model.


title: Kinematic Study of the Blazar 0716+714

abstract:
  We determined the kinematics at the jet of 0716+714 from a reanalysis of
multi-frequency VLBI data (5, 8.4, 15, 22 GHz) obtained during the last 10
years combined with data from the literature. For this intra-day variable
blazar, only a lower limit of its distance is known (z >= 0.3). We find that
0716+714 is a relatively fast superluminal source (with a Lorentz factor of
gamma >15), revising earlier results showing much slower motions. We discuss
the new findings with emphasis on the interpretation of the observed rapid
radio variability.


title:
A dynamical model for the distribution of dark matter and gas in galaxy
  clusters

abstract:
  Using high-resolution non-radiative hydrodynamic simulations of galaxy
clusters we obtain simple analytic formulae for DM and gas distribution in the
spherical approximation. We derive fits for the DM density, velocity dispersion
and velocity anisotropy. We use these models to test the dynamical equilibrium
hypothesis through the Jeans equation: we find that this is satisfied to good
accuracy. This result show that our fits constitute a self-consistent dynamical
model. We then extend our analysis to the gas, studying its density,
temperature and velocity structure, with no further hypothesis on the dynamical
status or state equation. Gas and DM show self-similar density profiles down to
0.06 R_vir, while at smaller radii the gas produces a central core. Gas
temperatures are almost isothermal out to 0.2 R_vir, then steeply decrease
reaching at R_vir a value a factor of 2 lower. We find that the gas is not at
rest inside R_vir: velocity dispersions are increasing functions of the radius,
motions are isotropic to slightly tangential, and contribute to the total
pressure support. We test our model using a generalization of the hydrostatic
equilibrium equation, where the gas motion is properly taken into account. We
find that our fits provide an accurate description of the system: the gas is in
equilibrium and is a good tracer the overall cluster potential if all terms are
taken into account, while simpler assumptions, as the beta-model, cause
systematic mass underestimates. We also find that, if gas velocities are
neglected, then a simple isothermal model fares better at large radii than a
non-isothermal one. (abridged)


title:
The End of the Dark Ages: Probing the Reionization of the Universe with
  HST and JWST

abstract:
  Limiting the number of model-dependent assumptions to a minimum, we discuss
the detectability of the sources responsible for reionization with existing and
planned telescopes. We conclude that if reionization sources are UV-efficient,
minimum luminosity sources, then it may be difficult to detect them before the
advent of the James Webb Space Telescope (JWST). The best approach before the
launch of JWST may be either to exploit gravitational lensing by clusters of
galaxies, or to search for strong Ly-alpha sources by means of narrow-band
excess techniques or slitless grism spectroscopy.


title: VSOP Observations of the EGRET Blazar 1633+382

abstract:
  Two high-resolution 5 GHz VSOP+VLBA images of the blazar 1633+382 reveal
clear morphological change in both the bright inner east-west jet, and in the
more diffuse structure further down the jet to the northwest. Here, we discuss
the motion of the inner jet as traced by these VSOP images and earlier VLBA
observations.


title:
Multi-Frequency VSOP and VLBA Polarization Observations of 3C279 and
  3C345

abstract:
  This contribution presents preliminary results from coordinated polarization
sensitive VSOP and VLBA imaging of the blazars 3C~279 and 3C~345 at multiple
frequencies.


title: The MAXIMA Experiment: Latest Results and Consistency Tests

abstract:
  The MAXIMA cosmic microwave background anisotropy experiment had a
significant impact on cosmology. Results from the program have played a
significant role in determining the geometry of the universe, given strong
supporting evidence to inflation, and, in combination with other astrophysical
data, showed that the universe is filled with dark matter and energy. We
present a subset of the internal consistency checks that were carried out on
the MAXIMA-1 data prior to their release, which demonstrate that systematics
errors were much smaller than statistical errors. We also discuss the MAXIMA-2
flight and data, compare the maps of MAXIMA-1 and -2 in areas where they
overlap and show that the two independent experiments confirm each other. All
of these results demonstrate that MAXIMA mapped the cosmic microwave background
anisotropy with high accuracy


title:
X-ray observations of 4 Draconis: symbiotic binary or cataclysmic
  triple?

abstract:
  We present the first X-ray observations of the 4 Draconis system, consisting
of an M3III giant with a hot ultraviolet companion. It has been claimed that
the companion is itself an AM Her-type binary system, an identification that
places strong constraints on the evolution of cataclysmic variables. We find
that the X-ray properties of 4 Draconis are consistent with the presence of an
accreting white dwarf, but not consistent with the presence of an AM Her
system. We conclude that 4 Dra is therefore most-likely a symbiotic binary
containing a white dwarf accreting material from the wind of the red giant.
  The X-ray spectrum of 4 Dra is sometimes dominated by partially-ionised
photoelectric absorption, presumably due to the wind of the red giant. We note
that X-ray monitoring of such systems would provide a powerful probe of the
wind and mass-loss rate of the giant, and would allow a detailed test of wind
accretion models.


title: Chameleon Cosmology

abstract:
  The evidence for the accelerated expansion of the universe and the
time-dependence of the fine-structure constant suggests the existence of at
least one scalar field with a mass of order H_0. If such a field exists, then
it is generally assumed that its coupling to matter must be tuned to
unnaturally small values in order to satisfy the tests of the Equivalence
Principle (EP). In this paper, we present an alternative explanation which
allows scalar fields to evolve cosmologically while having couplings to matter
of order unity. In our scenario, the mass of the fields depends on the local
matter density: the interaction range is typically of order 1 mm on Earth
(where the density is high) and of order 10-10^4 AU in the solar system (where
the density is low). All current bounds from tests of General Relativity are
satisfied. Nevertheless, we predict that near-future experiments that will test
gravity in space will measure an effective Newton's constant different by order
unity from that on Earth, as well as EP violations stronger than currently
allowed by laboratory experiments. Such outcomes would constitute a smoking gun
for our scenario.


title: Flat-Cored Dark Matter in Cuspy Clusters of Galaxies

abstract:
  Sand, Treu, & Ellis (2002) have measured the central density profile of
cluster MS2137-23 with gravitational lensing and velocity dispersion and
removed the stellar contribution with a reasonable M/L. The resulting dark
matter distribution within r<50 kpc was fitted by a density cusp of r^{-beta}
with beta=0.35. This stands in an apparent contradiction to the CDM prediction
of beta~1, and the disagreement worsens if adiabatic compression of the dark
matter by the infalling baryons is considered. Following El-Zant, Shlosman &
Hoffman (2001), we argue that dynamical friction acting on galaxies moving
within the dark matter background counters the effect of adiabatic compression
by transfering the orbital energy of galaxies to the dark matter, thus heating
up and softening the central density cusp. Using N-body simulations of massive
solid clumps moving in clusters we show that indeed the inner dark matter
distribution flattens (with beta approx 0.35 for a cluster like MS2137-23) when
the galaxies spiral inward. We find as a robust result that while the dark
matter distribution becomes core-like, the overall mass distribution preserves
its cuspy nature, in agreement with X-ray and lensing observations of clusters.


title: The MOJAVE Program: Studying the Relativistic Kinematics of AGN Jets

abstract:
  We discuss a new VLBA program to investigate structural and polarization
changes in the brightest AGN jets in the northern sky. Our study represents a
significant improvement over previous surveys in terms of image fidelity, size,
and completeness, and will serve to characterize the kinematics of AGN jets and
determine how these are related to other source properties. We discuss several
preliminary results from our program, including the detection of parsec-scale
circularly polarized jet emission, enhanced magnetic field ordering at the
sites of apparent bends, and intrinsic differences in the jets of strong- and
weak-lined AGN.


title:
MAXIMA: A Balloon-Borne Cosmic Microwave Background Anisotropy
  Experiment

abstract:
  We describe the Millimeter wave Anisotropy eXperiment IMaging Array (MAXIMA),
a balloon-borne experiment designed to measure the temperature anisotropy of
the Cosmic Microwave Background (CMB) on angular scales of 10' to 5 degrees .
MAXIMA mapped the CMB using 16 bolometric detectors in spectral bands centered
at 150 GHz, 240 GHz, and 410 GHz, with 10' resolution at all frequencies. The
combined receiver sensitivity to CMB anisotropy was ~40 microK/rt(sec).
Systematic parasitic contributions were minimized by using four uncorrelated
spatial modulations, thorough crosslinking, multiple independent CMB
observations, heavily baffled optics, and strong spectral discrimination.
Pointing reconstruction was accurate to 1', and absolute calibration was better
than 4%. Two MAXIMA flights with more than 8.5 hours of CMB observations have
mapped a total of 300 deg^2 of the sky in regions of negligible known
foreground emission. MAXIMA results have been released in previous
publications. MAXIMA maps, power spectra and correlation matrices are publicly
available at http://cosmology.berkeley.edu/maxima


title: Did a gamma-ray burst initiate the late Ordovician mass extinction?

abstract:
  Gamma-ray bursts (hereafter GRB) produce a flux of radiation detectable
across the observable Universe, and at least some of them are associated with
galaxies. A GRB within our own Ggalaxy could do considerable damage to the
Earth's biosphere; rate estimates suggest that a dangerously near GRB should
occur on average two or more times per billion years. At least five times in
the history of life, the Earth experienced mass extinctions that eliminated a
large percentage of the biota. Many possible causes have been documented, and
GRB may also have contributed. The late Ordovician mass extinction
approximately 440 million years ago may be at least partly the result of a GRB.
A special feature of GRB in terms of terrestrial effects is a nearly impulsive
energy input of order 10 s. Due to expected severe depletion of the ozone
layer, intense solar ultraviolet radiation would result from a nearby GRB, and
some of the patterns of extinction and survivorship at this time may be
attributable to elevated levels of UV radiation reaching the Earth. In addition
a GRB could trigger the global cooling which occurs at the end of the
Ordovician period that follows an interval of relatively warm climate. Intense
rapid cooling and glaciation at that time, previously identified as the
probable cause of this mass extinction, may have resulted from a GRB.

categories: astro-ph physics.ao-ph physics.bio-ph physics.geo-ph q-bio.PE


title: A Geometric Determination of the Distance to SN 1987A and the LMC

abstract:
  Using the definitive reductions of the IUE light curves by Sonneborn et al.
(1997) and an extensive set of HST images of SN 1987A we have repeated and
improved our original analysis (Panagia et al. 1991) to derive a better
determination of the distance to the supernova. In this way we have obtained an
absolute size of the ring R(abs) = (6.23 +/- 0.08)e17 cm and an angular size
R'' = 808 +/- 17 mas, which give a distance to the supernova d(SN1987A) = 51.4
+/- 1.2 kpc and a distance modulus (m-M)_SN1987A}} = 18.55 +/- 0.05. Allowing
for a displacement of SN 1987A position relative to the LMC center, the
distance to the barycenter of the Large Magellanic Cloud is also estimated to
be d(LMC)=51.7 +/- 1.3 kpc, which corresponds to a distance modulus of
(m-M)_LMC = 18.56 +/- 0.05.


title:
The Quest for Primordial Stellar Populations and the James Webb Space
  Telescope

abstract:
  The NASA/ESA/CSA James Webb Space Telescope (JWST) will be the successor to
the Hubble Space Telescope and may be launched as early as mid-2011. The key
scientific goals for JWST are discovering and understanding the formation of
the first stars and galaxies, the evolution of galaxies and the production of
elements by stars, and the process of star and planet formation. Within this
context, we discuss the expected properties of the first stellar generations in
the Universe. We find that it is possible to discern truly primordial
populations from the next generation of stars by measuring the metallicity of
high-z star forming objects. The very low background of JWST will enable it to
image and study first-light sources at very high redshifts, whereas its
relatively small collecting area limits its capability in obtaining spectra of
z~10--15 first-light sources to either the bright end of their luminosity
function or to strongly lensed sources. With a suitable investment of observing
time JWST will be able to detect individual Population III supernovae, thus
identifying the very first stars that formed in the Universe.


title: X-ray and UV observations of the dwarf nova VW Hyi in quiescence

abstract:
  We present an analysis of X-ray and ultra-violet data of the dwarf nova VW
Hyi that were obtained with XMM-Newton during the quiescent state. The X-ray
spectrum indicates the presence of an optically thin plasma in the boundary
layer that cools as it settles onto the white dwarf. The plasma has a
continuous temperature distribution that is well described by a power-law or a
cooling flow model with a maximum temperature of 6-8 keV. We estimate from the
X-ray spectrum a boundary layer luminosity of 8*10^30 erg/s, which is only 20
per cent of the disk luminosity. The rate of accretion onto the white dwarf is
5*10^-12 solar masses per year, about half of the rate in the disk. From the
high-resolution X-ray spectra, we estimate that the X-ray emitting part of the
boundary layer is rotating with a velocity of 540 km/s, which is close the
rotation velocity of the white dwarf but significantly smaller than the
Keplerian velocity. We detect a 60-s quasi-periodic oscillation of the X-ray
flux that is likely due to the rotation of the boundary layer. The X-ray and
the ultra-violet flux show strong variability on a time scale of ~1500 s. We
find that the variability in the two bands is correlated and that the X-ray
fluctuations are delayed by ~100 s. The correlation indicates that the variable
ultra-violet flux is emitted near the transition region between the disk and
the boundary layer and that accretion rate fluctuations in this region are
propagated to the X-ray emitting part of the boundary layer within ~100 s. An
orbital modulation of the X-ray flux suggests that the inner accretion disk is
tilted with respect to the orbital plane. The elemental abundances in the
boundary layer are close to their solar values.


title:
The bright optical afterglow of the nearby gamma-ray burst of 29 March
  2003

abstract:
  Many past studies of cosmological gamma-ray bursts (GRBs) have been limited
because of the large distance to typical GRBs, resulting in faint afterglows.
There has long been a recognition that a nearby GRB would shed light on the
origin of these mysterious cosmic explosions, as well as the physics of their
fireballs. However, GRBs nearer than z=0.2 are extremely rare, with an
estimated rate of localisation of one every decade. Here, we report the
discovery of bright optical afterglow emission from GRB 030329. Our prompt
dissemination and the brilliance of the afterglow resulted in extensive
followup (more than 65 telescopes) from radio through X-ray bands, as well as
measurement of the redshift, z=0.169. The gamma-ray and afterglow properties of
GRB 030329 are similar to those of cosmological GRBs (after accounting for the
small distance), making this the nearest known cosmological GRB. Observations
have already securely identified the progenitor as a massive star that exploded
as a supernova, and we anticipate futher revelations of the GRB phenomenon from
studies of this source.


title: A Physical Model for the joint evolution of QSOs and Spheroids

abstract:
  We summarize our detailed, physically grounded, model for the early
co-evolution of spheroidal galaxies and of active nuclei at their centers
(astro-ph/0307202). Our predictions are excellent agreement with observations
for a number of observables which proved to be extremely challenging for all
the current semi-analytic models, including the sub-mm counts and the
corresponding redshift distributions, and the epoch-dependent K-band luminosity
function of spheroidal galaxies. Also, the black hole mass function and the
relationship between the black hole mass and the velocity dispersion in the
galaxy are nicely reproduced.


title:
Observability of neutron events above the Greisen-Zatsepin-Kuzmin
  cut-off due to violation of Lorentz invariance

abstract:
  The clustering of ultra high energy cosmic ray events suggests that they have
originated from compact sources. One of the possible physical mechanisms by
which ultra high energy nuclei reach the Earth from far away astrophysical
sources (quasars or BL Lac objects) evading the
  Greisen-Zatsepin-Kuzmin (GZK) cut-off is by violation of Lorentz invariance.
Assuming that there is violation of Lorentz invariance, we calculate the
expected number of neutron events from some of the EGRET sources (including
$\gamma$-ray loud BL Lac objects) which can be correlated in direction with
ultra high energy cosmic ray events observed by AGASA above energy
$4\times10^{19}$eV.
  We present in this paper what AGASA should see in future if violation of
Lorentz invariance is responsible for the propagation of ultra high energy
cosmic rays having energies above the GZK cut-off when there is a correlation
of EGRET sources with the ultra high energy cosmic ray events.


title: Weak lensing, structure formation and dark energy

abstract:
  We study how CMB bispectrum, produced by weak gravitational lensing and
structure formation, can constrain the redshift evolution of the dark energy
equation of state independently on its present value. Analyzing the line of
sight contribution to the angular CMB bispectrum, we find that the relevant
redshift at which the structure formation contributes to the signal is $0.1
\lsim z \lsim 2$ for multipoles $1000 \gsim l \gsim 100$: just the epoch when
the dark energy starts to dominate the cosmological expansion rate. For
scenarios having the same equation of state at the present, this turns out to
be a new observable capable to discriminate between models of dark energy with
different time evolution of equation of state. We assess the strength of this
effetc within the framework of tracking Quintessence trajectories obeying SUGRA
and Ratra-Peebles potentials.


title:
CMB Comptonization in Clusters: Spectral and Angular Power from Evolving
  Polytropic Gas

abstract:
  The angular power spectrum of the Sunyaev-Zeldovich (SZ) effect is calculated
in the $\Lambda$CDM cosmological model with the aim of investigating its
detailed dependence on the cluster population, gas morphology, and gas
evolution. We calculate the power spectrum for three different mass functions,
compute it within the framework of isothermal and polytropic gas distributions,
and explore the effect of gas evolution on the magnitude and shape of the power
spectrum. We show that it is indeed possible to explain the `excess' power
measured by the CBI experiment on small angular scales as originating from the
SZ effect without (arbitrary) rescaling the value of $\sigma_8$, the mass
variance parameter. The need for a self-consistent choice of the basic
parameters characterizing the cluster population is emphasized. In particular,
we stress the need for a consistent choice of the value of $\sigma_8$ extracted
from fitting theoretical models for the mass function to the observed cluster
X-ray temperature function, such that it agrees with the mass-temperature
relation used to evaluate the cluster Comptonization parameter. Our treatment
includes the explicit spectral dependence of the thermal component of the
effect, which we calculate at various frequencies. We find appreciable
differences between the non-relativistic and relativistic predictions for the
power spectrum even for this superposed contribution from clusters at the full
range of gas temperatures.


title: SIMBOL-X : a new generation hard X-ray telescope

abstract:
  SIMBOL-X is a hard X-ray mission, operating in the 0.5-70 keV range, which is
proposed by a consortium of European laboratories for a launch around 2010.
Relying on two spacecraft in a formation flying configuration, SIMBOL-X uses a
30 m focal length X-ray mirror to achieve an unprecedented angular resolution
(30 arcsec HEW) and sensitivity (100 times better than INTEGRAL below 50 keV)
in the hard X-ray range. SIMBOL-X will allow to elucidate fundamental questions
in high energy astrophysics, such as the physics of accretion onto Black Holes,
of acceleration in quasar jets and in supernovae remnants, or the nature of the
hard X-ray diffuse emission. The scientific objectives and the baseline
concepts of the mission and hardware design are presented.


title: X-ray Evidence for a Buried Active Galactic Nucleus in UGC 5101

abstract:
  We present X-ray observations of the ultraluminous infrared galaxy, UGC 5101,
thought to contain a buried active galactic nucleus (AGN) based on observations
in other wavebands. We detected an absorbed hard component at >3 keV, as well
as soft emission in the energy range 0.5-2 keV. The soft X-ray component,
possibly due to a modestly dust-obscured, extended starburst, has an
absorption-corrected 0.5-2 keV X-ray luminosity of LX(0.5-2 keV) = 1.2 * 10^41
ergs s^-1. The 0.5-2 keV X-ray to infrared luminosity ratio is a factor of 5
lower than typical values for a normal starburst, suggesting that this extended
starburst is unlikely to be energetically dominant in UGC 5101. The most
plausible origin of the absorbed hard component is the putative buried AGN. The
6.4 keV Fe K alpha emission line has a modest equivalent width (400 eV),
suggesting that this hard component is direct emission from the AGN, rather
than a scattered component. The absorption-corrected 2-10 keV X-ray luminosity
of the buried AGN was estimated to be LX(2-10 keV) = 5 * 10^42 ergs s^-1. The
intrinsic 2-10 keV X-ray luminosity and the 2-10 keV X-ray to infrared
luminosity ratio are both comparable to values measured for Mrk 463, a
Seyfert-2 galaxy of similar infrared luminosity.


title: UBR charge-coupled device photometry of Stromlo-APM galaxies

abstract:
  We present CCD photometry in the Johnson-Kron-Cousins UBR bands for a sample
of 320 galaxies selected from the Stromlo-APM Redshift Survey. We use this CCD
data to estimate the galaxy luminosity function in the U, B, R and b_J bands,
finding consistent results with earlier work. Fainter galaxies serendipitously
observed on our CCD frames allow a check of the photometric calibration of the
APM Galaxy Survey. We find no evidence of any significant scale error in the
APM magnitudes.


title:
XMM-Newton Observations of the Perseus Cluster II: Evidence for Gas
  Motions in the Core

abstract:
  The 5-9 keV spectrum of the inner ~100 kpc of the Perseus cluster measured by
XMM-Newton can be well described by an optically thin plasma emission model as
predicted by the APEC code, without any need for invoking a strong Ni
overabundance or the effects of resonant scattering. For the strongest 6.7 keV
line of He-like iron, the optical depth of the cluster, calculated using
observed density, temperature and abundance profiles, is of order 3. The lack
of evidence for resonant scattering effects implies gas motion in the core with
a range in velocities of at least half of the sound velocity. If this motion
has the character of small scale turbulence, then its dissipation would provide
enough energy to compensate for radiative cooling of the gas. The activity of
the supermassive black hole at the center of the cluster may be the driving
force of the gas motion.


title:
Reopening the TNOs Color Controversy: Centaurs Bimodality and TNOs
  Unimodality

abstract:
  We revisit the Trans-Neptunian Objects (TNOs) color controversy allegedly
solved by Tegler and Romanishin 2003. We debate the statistical approach of the
quoted work and discuss why it can not draw the claimed conclusions, and
reanalyze their data sample with a more adequate statistical test. We find
evidence for the existence of two color groups among the Centaurs. Therefore,
mixing both centaurs and TNOs populations lead to the erroneous conclusion of a
global bimodality, while there is no evidence for two color groups in the TNOs
population alone. We use quasi-simultaneous visible color measurements
published for 20 centaurs (corresponding to about half of the identified
objects of this class), and conclude on the existence of two groups. With the
surface evolution model of Delsanti et al. (2003) we discuss how the existence
of two groups of Centaurs may be compatible with a continuous TNOs color
distribution.


title: Evolution of the Galaxy Luminosity Function at z < 0.3

abstract:
  We measure the redshift-dependent luminosity function and the comoving radial
density of galaxies in the Sloan Digital Sky Survey Data Release 1 (SDSS DR1).
Both measurements indicate that the apparent number density of bright galaxies
increases by a factor ~3 as redshift increases from z=0 to z=0.3. This result
is robust to the assumed cosmology, to the details of the K-correction and to
direction on the sky. These observations are most naturally explained by
significant evolution in the luminosity and/or number density of galaxies at
redshifts z < 0.3. Such evolution is also consistent with the steep
number-magnitude counts seen in the APM Galaxy Survey, without the need to
invoke a local underdensity in the galaxy distribution distribution or
magnitude scale errors.


title:
The origin of emission and absorption features in Ton S180 Chandra
  observations

abstract:
  We present new interpretation of Ton S180 spectrum obtained by {\it Chandra}
Spectrometer (Low Energy Transmission Grating). Several narrow absorption lines
and a few emission disk lines have been successfully fitted to the data. We
have not found any significant edges accompanying line emission. We propose the
interpretation of narrow lines consistent with the paper recently written by
Krolik (2002), where warm absorber is strongly inhomogeneous. Such situation is
possible in so called multi-phase medium, where regions with different
ionization states, densities and temperatures may coexist in thermal
equilibrium under constant pressure. We illustrate this scenario with
theoretical spectra of radiation transfered through a stratified cloud with
constant pressure (instead of constant density) computed by code {\sc titan} in
plane parallel approximation. Detected spectral features are faint and their
presence do not alter the broad band continuum. We model the broad band
continuum of Ton S180 assuming an irradiated accretion disk with a dissipative
warm skin. The set of parameters appropriate for the data cannot be determined
uniquely but models with low values of the black hole mass have too hot and
radially extended warm skin to explain the formation of soft X-ray disk lines
seen in the data.


title:
Timing and spectral studies of LMC X-4 in high and low states with
  Beppo-SAX: Detection of pulsations in the soft spectral component

abstract:
  We report here detailed timing and spectral analysis of two Beppo-SAX
observations of the binary X-ray pulsar LMC X-4 carried out during the low and
high states of its 30.5 days long super-orbital period. Timing analysis clearly
shows 13.5 s X-ray pulsations in the high state of the super-orbital period
which allows us to measure the mid-eclipse time during this observation.
Combining this with two other mid-eclipse times derived earlier with the ASCA,
we derived a new estimate of the orbital period derivative. Pulse-phase
averaged spectroscopy in the high and low states shows that the energy spectrum
in the 0.1 - 10 keV band comprises of a hard power-law, a soft excess, and a
strong iron emission line. The continuum flux is found to decrease by a factor
of ~ 60 in the low state while the decrease in the iron line flux is only by a
factor of ~ 12, suggesting a different site for the production of the line
emission. In the low state, we have not found any significant increase in the
absorption column density. The X-ray emission is found to come from a very
large region, comparable to the size of the companion star. Pulse phase
resolved spectroscopy in the high state shows a pulsating nature of the soft
spectral component with some phase offset compared to the hard X-rays, as is
known in some other binary X-ray pulsars.


title:
The hard X-ray spectrum of the Seyfert galaxy IRAS 18325-5926: cool
  corona, reflection from an ionized disk and variable iron K emission

abstract:
  We report our analysis of X-ray spectra of the Seyfert galaxy IRAS 18325-5926
(=Fairall 49) obtained from various X-ray observatories prior to XMM-Newton,
including new results from two RXTE and one BeppoSAX observations. A relatively
steep continuum slope (photon-index of ~2.2) in the 2-15 keV band is confirmed.
The continuum spectrum observed with the BeppoSAX PDS shows a possible
roll-over at energies above 30 keV, indicating a Comptonizing corona cooler
than in other Seyfert nuclei. The X-ray spectrum above 2 keV is best explained
with a model including reflection from a highly ionized disk with significant
relativistic blurring. The iron K-alpha emission feature is then mainly due to
FeXXV. The recent seven observations shows that the iron K emission flux
appears to follow the continuum between the observations separated by a few
months to years, although some exceptions suggest that the line strength may be
determined in a more complex way.


title:
Evolution of Rotating Accreting White Dwarfs and the Diversity of Type
  Ia Supernovae

abstract:
  Type Ia supernovae (SNe Ia) have relatively uniform light curves and spectral
evolution, which make SNe Ia useful standard candles to determine cosmological
parameters. However, the peak brightness is not completely uniform, and the
origin of the diversity has not been clear. We examine whether the rotation of
progenitor white dwarfs (WDs) can be the important source of the diversity of
the brightness of SNe Ia. We calculate the structure of rotating WDs with an
axisymmetric hydrostatic code. The diversity of the mass induced by the
rotation is ~0.08 Msun and is not enough to explain the diversity of
luminosity. However, we found the following relation between the initial mass
of the WDs and their final state; i.e., a WD of smaller initial mass will
rotate more rapidly before the supernova explosion than that of larger initial
mass. This result might explain the dependence of SNe Ia on their host
galaxies.


title: Partially ionizing the universe by decaying particles

abstract:
  We show that UV photons produced by decaying particles can partially reionize
the universe and explain the large optical depth observed by Wilkinson
Microwave Anisotropy Probe. Together with UV fluxes from early formed stars and
quasars, it is possible that the universe is fully ionized at z \lesssim 6 and
partially ionized at z \gtrsim 6 as observed by Sloan Digital Sky Survey for
large parameter space of the decaying particle. This scenario will be
discriminated by future observations, especially by the EE polarization power
spectrum of cosmic microwave background radiation.


title: The entropy distribution in clusters: evidence of feedback?

abstract:
  The entropy of the intracluster medium at large radii has been shown recently
to deviate from the self-similar scaling with temperature. Using
N-body/hydrodynamic simulations of the LCDM cosmology, we demonstrate that this
deviation is evidence that feedback processes are important in generating
excess entropy in clusters. While radiative cooling increases the entropy of
intracluster gas, resulting in a good match to the data in the centres of
clusters, it produces an entropy-temperature relation closer to the
self-similar scaling at larger radii. A model that includes feedback from
galaxies, however, not only stabilises the cooling rate in the simulation, but
is capable of reproducing the observed scaling behaviour both in cluster cores
and at large radii. Feedback modifies the entropy distribution in clusters due
to its increasing ability at expelling gas from haloes with decreasing mass.
The strength of the feedback required, as suggested from our simulations, is
consistent with supernova energetics, providing a large fraction of the energy
reaches low-density regions and is originally contained within a small mass of
gas.


title: High frequency features in the 1998 outburst of 4U 1630-47

abstract:
  We report on the detection with RXTE of variable high frequency features in
the power spectra of the black hole candidate 4U 1630-47 during its 1998
outburst. We find high frequency features during the rise and the early decay
of the outburst in the range of 100-300 Hz. The features are usually found to
be broad, and have rms amplitudes of 2-8; their frequencies are correlated with
count rate and anti-correlated with spectral hardness. Also, for the first time
twin high frequency features are detected simultaneously, with a ratio in
frequencies consistent with 1:4. Although some of the high frequency features
are less coherent and stronger than found in other black hole sources, we show
that they behave very similar to the high frequency features found in for
instance XTE J1550-564.


title: A transient variable 6 Hz QPO from GX 339-4

abstract:
  We report the results of an observation with the Rossi X-ray Timing Explorer
of the black hole candidate GX 339-4 during its 2002/2003 outburst. This
observation took place during a spectral transition from the hard to the soft
state. A strong (6% rms) transient quasi-periodic oscillation (QPO) appears
suddenly in the power density spectrum during this observation. The QPO
centroid is ~6 Hz, but it varies significantly between 5 and 7 Hz with a
characteristic time scale of ~10 seconds, correlated with the 2-30 keV count
rate. The appearance of the QPO is related to spectral hardening of the flux,
due to a change in the relative contribution of the soft and hard spectral
components. We compare this peculiar behavior with results from other systems
that show similar low frequency QPO peaks, and discuss the results in terms of
possible theoretical models for QPO production.


title: Polarization Measures And Nature Of Dark Energy

abstract:
  Polarization measures, on wide angular scales, together with anisotropy data,
can fix DE parameters. Here we discuss the sensitivity needed to provide
significant limits. Our analysis puts in evidence that a class of models
predicts low correlation or anticorrelation between polarization and anisotropy
at low l. This class includes open models and models with DE due to a
Ratra--Peebles (RP) potential. Results on this point, given in a previous paper
of ours, are updated and partially corrected. We outline that, with the
sensitivity of experiments like SPOrt or WMAP, high values of Lambda (energy
scale in the RP potential) can be excluded. With the sensitivity expected for
PLANCK, the selection will extend to much lower Lambda's.


title: Structure Formation in Dynamical Dark Energy Models

abstract:
  We perform N-body simulations for models with a DE component. Besides of DE
with constant negative state parameter w, we consider DE due to scalar fields,
self-interacting through RP or SUGRA potentials. According to our post-linear
analysis, at z=0, DM power spectra and halo mass functions do not depend on DE
nature. This is welcome, as LCDM fits observations. Halo profiles, instead, are
denser than LCDM. For example, the density at 15 kpc of a DE halo with M=10^13
exceeds LCDM by ~45%. Differences, therefore, are small but, however, DE does
not ease the problem with cuspy DM profiles. We study also subhalos and find
that, at $z=0$, the number of satellites coincides in all DE models. At higher
z, DE models show increasing differences from LCDM and among themselves (i.e.
in the mass function evolution); this is the obvious pattern to distinguish
between different DE state equations.


title: Radiative Transfer in Spiral Galaxies

abstract:
  The internal dust extinction in spiral galaxies can affect our understanding
of their structure and morphology, as well as our perception of the distant
universe in the background. The intrinsic properties of the stellar and dust
components can be studied by comparing the observed appearance of a dusty
spiral in the optical with a radiative transfer model. The absorbed starlight
is re-radiated by dust in the FIR/sub-mm. Thus, observations at long
wavelengths allow to put further constraints on the properties of the dust
distribution. I present our Monte Carlo simulations for dust extinction and
emission in galactic disks, discuss the basic ingredients and limitations and
compare them with other solutions for the radiative transfer available in the
literature. I review the current picture of dusty disks that emerges from
radiative transfer studies.


title:
Measuring the Cluster Magnetic Field Power Spectra from Faraday Rotation
  Maps of Abell 400, Abell 2634 and Hydra A

abstract:
  We apply a novel technique of Faraday Rotation measure (RM) map analysis to
three galaxy clusters, Abell 400, Abell 2634 and Hydra A, in order to estimate
cluster magnetic field strengths, length scales and power spectra. This
analysis is based on the assumption that the magnetic fields are statistically
isotropically distributed across the Faraday screen. We investigate the
difficulties involved in the application of the analysis to observational data.
We derive magnetic power spectra for the three clusters and discuss influences
on their shapes. We show that magnetic fluctuations are probed on length scales
ranging over at least one order of magnitude. Using this range for the
determination of central cluster magnetic field strength yields 3 muG in Abell
2634, 6 muG in Abell 400 and 12 muG in Hydra A. The magnetic field
autocorrelation length was determined to be 4.9 kpc for Abell 2634, 3.6 kpc for
Abell 400 and 0.9 kpc for Hydra A. We show that the RM autocorrelation length
is larger than the magnetic field autocorrelation length. We investigate in a
response analysis if it is possible to determine spectral slopes of the power
spectra. We find that integrated numbers can be determined from this analysis
but differential parameters such as spectral slopes have to be treated
differently. Our response analysis results in spectral slopes of the power
spectra of spectral indices alpha = 1.6 to 2.0 suggesting that Kolmogorov
spectra are possible but flatter spectral slopes than alpha = 1.3 can be
excluded.


title:
Early SPI/INTEGRAL contraints on the morphology of the 511 keV line
  emission in the 4th galactic quadrant

abstract:
  We provide first constraints on the morphology of the 511 keV line emission
from the galactic centre region on basis of data taken with the spectrometer
SPI on the INTEGRAL gamma-ray observatory. The data suggest an azimuthally
symmetric galactic bulge component with FWHM of ~9 deg with a 2 sigma
uncertainty range covering 6-18 deg. The 511 keV line flux in the bulge
component amounts to (9.9+4.7-2.1) 10e-4 ph cm-2 s-1. No evidence for a
galactic disk component has been found so far; upper 2 sigma flux limits in the
range (1.4-3.4) 10e-3 ph cm-2 s-1 have been obtained that depend on the assumed
disk morphology. These limits correspond to lower limits on the bulge-to-disk
ratio of 0.3-0.6.


title: TeV Blazars - Observations and Models

abstract:
  Since the first TeV blazar Markarian (Mrk) 421 was detected in 1992, the
number of established TeV gamma-ray emitting BL Lac objects has grown to 6,
with redshifts ranging from 0.031 (Mrk 421) to 0.129 (H 1426+428). The
intensive study of these sources has had a major impact on our understanding of
the blazar phenomenon. The most notable observational results have been
extremely fast large amplitude flux and spectral variability on hour time
scales, and a pronounced X-ray - TeV gamma-ray flux correlation. In this paper
we discuss recent observational results and report on progress in their
theoretical interpretation.


title:
Analysis of polarized microwave emission of Flare-Productive Active
  Region 9415

abstract:
  The results of the microwave observations of the Sun made with the RATAN-600
have shown the existence of many types of spectral peculiarities in polarized
emission of active regions, which produce powerful flares. These phenomena
happen at microwaves and reflect inhomogeneous structure of magnetic field in
magnetospheres of flaring active regions in wide range of heights above the
photosphere. In this presentation we demonstrate an analysis of the AR 9415
during all the period of its passage across the solar disk. Results of the
study point out to existence of different scenarios of circular polarization
variations in the radio wave band. Here, we separated the phenomenon of the
cyclotron emission passage through the quasi-transverse magnetic field
(QT-region) and several effects connected with flare activity of active region.
New observational data are presented and compared with the data of several
observatories: SSRT, NoRH, MDI SOHO, GOES and MEES. The preliminary
interpretation of the phenomena are given.


title: XMM-Newton Observations of PSR B1706-44

abstract:
  We report on the XMM-Newton observations of the young, 102 ms pulsar PSR
B1706-44. We have found that both a blackbody plus power-law and a magnetized
atmospheric model plus power-law provide an excellent fit to the EPIC spectra.
The two scenarios are therefore indistinguishable on a statistical basis,
although we are inclined to prefer the latter on physical grounds. In this
case, assuming a source distance of ~2.3 kpc, the size of the region
responsible for the thermal emission is R~13 km, compatible with the surface of
a neutron star. A comparison of the surface temperature of PSR B1706-44
obtained from this fit with cooling curves favor a medium mass neutron star
with M~1.45 solar masses or M~1.59 solar masses, depending on two different
models of proton superfluidity in the interior. The large collecting area of
XMM-Newton allows us to resolve a substructure in the broad soft X-ray
modulation detected by Chandra, revealing the presence of two separate peaks
with pulsed fractions of 7 +/- 4% and 15 +/- 3%, respectively.