title:
B-field Determination from Magnetoacoustic Oscillations in kHz QPO
  Neutron Star Binaries: Theory and Observations

abstract:
  We present a method for determining the B-field around neutron stars based on
observed kHz and viscous QPO frequencies used in combination with the best-fit
optical depth and temperature of a Comptonization model. In the framework of
the transition layer QPO model, we analyze magnetoacoustic wave formation in
the layer between a neutron star surface and the inner edge of a Keplerian
disk. We derive formulas for the magnetoacoustic wave frequencies for different
regimes of radial transition layer oscillations. We demonstrate that our model
can use the QPO as a new kind of probe to determine the magnetic field
strengths for 4U 1728-42, GX 340+0, and Sco X-1 in the zone where the QPOs
occur. Observations indicate that the dependence of the viscous frequency on
the Keplerian frequency is closely related to the inferred dependence of the
magnetoacoustic wave frequency on the Keplerian frequency for a dipole magnetic
field. The magnetoacoustic wave dependence is based on a single parameter, the
magnetic moment of the star as estimated from the field strength in the
transition layer. The best-fit magnetic moment parameter is about (0.5-1)x
10^{25} G cm^3 for all studied sources. From observational data, the magnetic
fields within distances less 20 km from neutron star for all three sources are
strongly constrained to be dipole fields with the strengths 10^{7-8} G on the
neutron star surface.


title:
Asteroseismology of delta Scuti stars - a parameter study and
  application to seismology of FG Virginis

abstract:
  We assess the potential of asteroseismology for determining the fundamental
properties of individual $\delta$ Scuti stars. We computed a grid of evolution
and adiabatic pulsation models using the Yale Rotating Evolution Code to study
the systematic changes in low-order ($\ell = 0, 1, 2,$ and 3) modes as
functions of fundamental stellar properties. Changes to the stellar mass,
chemical composition, and convective core overshooting length change the
observable pulsation spectrum significantly. In general, mass has the strongest
effect on evolution and on pulsation, followed by the metal abundance. Changes
to the helium content have very little effect on the frequencies until near the
end of the main sequence. Changes to each of the four parameters change the
$p$-mode frequencies more, both in absolute and relative terms, than they do
the $g$- and mixed-mode frequencies, suggesting that these parameters have a
greater effect on the outer layers of the star.
  We also present evolution and pulsation models of the well-studied star FG
Virginis, outlining a possible method of locating favorable models in the
stellar parameter space based upon a definitive identification of only two
modes. Specifically, we plot evolution models on the (period-period ratio) and
(temperature-period ratio) planes to select candidate models, and modify the
core overshooting parameter to fit the observed star. For these tests, we
adjusted only the mass, helium and metal abundances, and core overshooting
parameter, but this method can be extended to include the effects of
first-order rotational splitting and second-order rotational distortion of
pulsation spectra.


title: Luminosities and Space Densities of Short Gamma-Ray Bursts

abstract:
  Using the Euclidean value of <V/Vmax> as a cosmological distance indicator,
we derive the isotropic-equivalent characteristic peak luminosity of gamma-ray
bursts both longer and shorter than 2 s. The short bursts have essentially the
same characteristic peak luminosity of 0.6 x 10^51 erg (0.064s)^-1 as do the
long bursts. This may apply also to bursts with durations less than 0.25 s. The
local space density of short bursts is around three times lower than that of
long bursts.


title:
The photoionization effect of the ultraviolet background on the
  colour-magnitude relation of elliptical galaxies

abstract:
  We examined effects of the ultraviolet background radiation (UVB) on the
colour--magnitude relation (CMR) of elliptical galaxies in clusters of galaxies
in the hierarchical clustering scenario by using a semi-analytic model of
galaxy formation. In our model the UVB photoionizes gas in dark haloes and
suppresses the cooling of the diffuse hot gas onto galaxy discs. By using a
semi-analytic model without the effect of the UVB, Kauffmann & Charlot found
that the CMR can be reproduced by strong supernova heating because such
supernova feedback suppresses the chemical enrichment in galaxies especially
for small galaxies. We find that the CMR also becomes bluer because of the UVB,
in a different way from the effect of supernova feedback. While the supernova
feedback suppresses the chemical enrichment by a similar mechanism to galactic
wind, the UVB suppresses the cooling of the hot gas. This fact induces the
suppression of the metallicity of the intracluster medium (ICM). In our model
we find that the existence of the UVB can plausibly account for an observed ICM
metallicity that is equal to nearly 0.3 times the solar value, and that in this
case we can reproduce the CMR and the metallicity of the ICM simultaneously.


title:
Black Holes and Hosts of Active and Quiescent Galaxies: I. The Black
  Hole-Bulge Relation revisited

abstract:
  Massive Black Holes detected in the centers of many nearby galaxies show an
approximately linear relation with the luminosity of the host bulge, with the
black hole mass being 0.001-0.002 of the bulge mass. Previous work suggested
that black holes of active (Seyfert 1) galaxies follow a similar relation, but
apparently with a significantly lower value of $M_{\rm BH}/M_{\rm bulge}$
(Wandel 1999). New data show that this difference was mainly due to
overestimating the black hole mass in quiescent galaxies and overestimating the
bulge magnitude of Seyfert galaxies. Using new and updated data we show that
AGNs (Seyfert galaxies and quasars) follow the same BH-bulge relation as
ordinary (inactive) galaxies. We derive the BH-bulge relation for a sample of
55 AGNs and 35 quiescent galaxies, finding that broad line AGNs have an average
black hole/bulge mass fraction of $\sim 0.0015$ with a strong correlation (Mbh
~ Lbulge^{0.9\pm 0.16}). This BH-bulge relation is consistent with the BH-bulge
relation of quiescent galaxies and much tighter than previous results. Narrow
line AGNs appear to have a lower ratio, Mbh/Mbulge ~ 10^{-4}-10^{-3}. We find
this to be a more general feature, the BH/bulge ratio in AGNs being inversely
correlated with the emission-line width, implying a strong linear relation
between the size of the broad emission line region and the luminosity of the
bulge. Finally, combining AGNs with observed and estimated stellar velocity
dispersion, we find a significant correlation (Mbh ~ v^{3.5-5}), consistent
with that of quiescent galaxies.


title:
Hubble Constant at Intermediate Redshift using the CO-Line Tully-Fisher
  Relation

abstract:
  We have determined distances and Hubble ratios for galaxies at intermediate
redshifts, cz=about 10,000 to 35,000 km/s, by applying the CO-line Tully-Fisher
relation to our 12CO (J=1-0)-line observations using the Nobeyama 45-m
telescope, and near-IR (NIR) photometry in the J and H bands using the 1.88-m
telescope at Okayama Astrophysical Observatory. By averaging the Hubble ratios
from J-band result, we obtain a Hubble constant of H_0 = 60 (+/- 10) km/s/Mpc.
We argue that the CO line-NIR TFR can be a complimentary method to the other
methods for measuring distances of galaxies at intermediate and high redshifts.


title: GeV-TeV Gamma-ray Astronomy

abstract:
  Recent results of GeV and TeV observations of gamma-rays from the Universe
are briefly reviewed. Topics include observational technique, diffuse
gamma-rays, pulsars, unidentified sources, plerions, supernova remnants and
AGNs.


title: Criterion for Generation of Winds from Magnetized Accretion Disks

abstract:
  An analytic model is proposed for non-radiating accretion flows accompanied
by up or down winds in a global magnetic field. Physical quantities in this
model solution are written in variable-separated forms, and their radial parts
are simple power law functions including one parameter for wind strength.
Several, mathematically equivalent but physically different expressions of the
criterion for wind generation are obtained. It is suggested also that the
generation of wind is a consequence of the intervention of some mechanism that
redistributes the locally available gravitational energy, and that the
Bernoulli sum can be a good indicator of the existence of such mechanisms.


title: EVN observations of low-luminosity flat-spectrum AGNs

abstract:
  We present and discuss the results of VLBI (EVN) observations of three
low-luminosity (P(5 GHz)<10^25 W/Hz) Broad Emission Line AGNs carefully
selected from a sample of flat spectrum radio sources (CLASS). Based on the
total and the extended radio power at 5 GHz and at 1.4 GHz respectively, these
objects should be technically classified as radio-quiet AGN and thus the origin
of their radio emission is not clearly understood. The VLBI observations
presented in this paper have revealed compact radio cores which imply a lower
limit on the brightness temperature of about 3X10^8 K. This result rules out a
thermal origin for the radio emission and strongly suggests an emission
mechanism similar to that observed in more powerful radio-loud AGNs. Since, by
definition, the three objects show a flat (or inverted) radio spectrum between
1.4 GHz and 8.4 GHz, the observed radio emission could be relativistically
beamed. Multi-epoch VLBI observations can confirm this possibility in two years
time.


title:
The impact of dust and ionization effects on abundance measurements of
  Damped Ly alpha systems

abstract:
  Studies of elemental abundances are a fundamental tool for unveiling the
nature of the high-redshift (proto-)galaxies associated to Damped Ly alpha
systems (DLAs). The present contribution analyses the impact of dust and
ionization effects on abundance measurements in DLAs. The behaviour of the
alpha/Fe abundance ratio corrected for such effects is used to derive
information on the chemical history and nature of DLA galaxies. The alpha/Fe
data indicate that DLAs at z~2.5 do not represent a homogeneous class of
objects. On average, DLAs show non-enhanced alpha/Fe ratios at low metallicity,
suggesting an origin in galaxies with low or intermittent star formation rates.


title:
Exact solutions of the aspherical axisymmetric gravo-magnetic
  condensation

abstract:
  We find exact and explicit solutions of the axisymmetric MHD equations of a
self-gravitating polytropic gas. These solutions are able to describe a flat
(uniform density) subsonic internal core, contracting homologously, of a
collapsing cloud with aspherical pressure, aspherical gravitationnal potential,
magnetic field and rotation. Two of the solutions describing the collapse of a
rotating and magnetized cloud present outflow at the pole or at the equator.


title: The CLASS blazar survey. I - selection criteria and radio properties

abstract:
  This paper presents a new complete and well defined sample of Flat Spectrum
Radio Sources (FSRS) selected from the CLASS survey with the further constraint
of a bright (mag<17.5) optical counterpart. The sample has been designed to
produce a large number of low-luminosity blazars in order to test the current
unifying models in the low luminosity regime. In this first paper the new
sample is presented and the radio properties of the 325 sources contained
therein discussed.


title: Jet Collimation by Small-Scale Magnetic Fields

abstract:
  A popular model for jet collimation is associated with the presence of a
large-scale and predominantly toroidal magnetic field originating from the
central engine (a star, a black hole, or an accretion disk). Besides the
problem of how such a large-scale magnetic field is generated, in this model
the jet suffers from the fatal long-wave mode kink magnetohydrodynamic
instability. In this paper we explore an alternative model: jet collimation by
small-scale magnetic fields. These magnetic fields are assumed to be local,
chaotic, tangled, but are dominated by toroidal components. Just as in the case
of a large-scale toroidal magnetic field, we show that the ``hoop stress'' of
the tangled toroidal magnetic fields exerts an inward force which confines and
collimates the jet. The magnetic ``hoop stress'' is balanced either by the gas
pressure of the jet, or by the centrifugal force if the jet is spinning. Since
the length-scale of the magnetic field is small (< the cross-sectional radius
of the jet << the length of the jet), in this model the jet does not suffer
from the long-wave mode kink instability. Many other problems associated with
the large-scale magnetic field are also eliminated or alleviated for
small-scale magnetic fields. Though it remains an open question how to generate
and maintain the required small-scale magnetic fields in a jet, the scenario of
jet collimation by small-scale magnetic fields is favored by the current study
on disk dynamo which indicates that small-scale magnetic fields are much easier
to generate than large-scale magnetic fields.


title:
Structure of Protostellar Collapse Candidate B335 Derived from
  Near-Infrared Extinction Maps

abstract:
  We present a near-infrared extinction study of the dark globule B335, a
protostellar collapse candidate, using data from HST/NICMOS and the W.M. Keck
Observatory. These data allow a new quantitative test of the "inside-out"
collapse model previously proposed to explain molecular line profiles observed
toward this region. We find that the shape of the density profile is well
matched by the collapse model, but that the amount of extinction corresponds to
larger column densities than predicted. An unstable Bonnor-Ebert sphere with
dimensionless outer radius xi_max=12.5+/-2.6 provides an equally good
description of the density profile, and is indistinguishable from the collapse
model over the range in radius sampled by the data. The bipolar outflow driven
by the embedded YSO has an important effect on the extinction through the core,
and modeling the outflow as a hollowed-out bipolar cone of constant opening
angle provides a good match to theobservations. The complete exinction map is
well reproduced by a model that includes both infall and outflow, and an extra
20% dispersion that likely results from residual turbulent motions. This fitted
model has an infall radius of R_inf=26"+/-3"(0.031pc for 250pc distance), and
an outflow cone semi-opening angle of alpha=41+/-2 degrees. The fitted infall
radius is consistent with those derived from molecular line observations and
supports the inside-out collapse interpretation of the density structure. The
fitted opening angle of the outflow is slightly larger than observed in CO
emission, perhaps because the full extent of the outflow cone in CO becomes
confused with ambient core emission at low velocities.


title: The Role of Tidal Interactions in Star Formation

abstract:
  Nearly all of the initial angular momentum of the matter that goes into each
forming star must somehow be removed or redistributed during the formation
process. The possible transport mechanisms and the possible fates of the excess
angular momentum are discussed, and it is argued that transport processes in
disks are probably not sufficient by themselves to solve the angular momentum
problem, while tidal interactions with other stars in forming binary or
multiple systems are likely to be of very general importance in redistributing
angular momentum during the star formation process. Most, if not all, stars
probably form in binary or multiple systems, and tidal torques in these systems
can transfer much of the angular momentum from the gas around each forming star
to the orbital motions of the companion stars. Tidally generated waves in
circumstellar disks may contribute to the overall redistribution of angular
momentum. Stars may gain much of their mass by tidally triggered bursts of
rapid accretion, and these bursts could account for some of the most energetic
phenomena of the earliest stages of stellar evolution, such as jet-like
outflows. If tidal interactions are indeed of general importance,
planet-forming disks may often have a more chaotic and violent early evolution
than in standard models, and shock heating events may be common. Interactions
in a hierarchy of subgroups may play a role in building up massive stars in
clusters and in determining the form of the upper IMF. Many of the processes
discussed here have analogs on galactic scales, and there may be similarities
between the formation of massive stars by interaction-driven accretion
processes in clusters and the buildup of massive black holes in galactic
nuclei.


title: The origin of the Local Bubble

abstract:
  The Sun is located in a low-density region of the interstellar medium
partially filled with hot gas that is the likely result of several nearby
supernova explosions within the last 10 Myr. Here we use astrometric data to
show that part of the Scorpius-Centaurus OB association was located closer to
the present position of the Sun 5-7 Myr ago than today. Evolutionary synthesis
models indicate that the association must have experienced ~20 supernova
explosions in the last 10-12 Myr, a prediction that is supported by the
detection of four or five runaway stars escaping from it. The ~6 SNe produced
by the Lower Centaurus Crux subgroup are likely responsible for the creation of
the Local Bubble.


title: An X-Ray Study of the Supernova Remnant G290.1-0.8

abstract:
  G290.1-0.8 (MSH 11-61A) is a supernova remnant (SNR) whose X-ray morphology
is centrally bright. However, unlike the class of X-ray composite SNRs whose
centers are dominated by nonthermal emission, presumably driven by a central
pulsar, we show that the X-ray emission from G290.1-0.8 is thermal in nature,
placing the remnant in an emerging class which includes such remnants as W44,
W28, 3C391, and others. The evolutionary sequence which leads to such X-ray
properties is not well understood. Here we investigate two scenarios for such
emission: evolution in a cloudy interstellar medium, and early-stage evolution
of a remnant into the radiative phase, including the effects of thermal
conduction. We construct models for these scenarios in an attempt to reproduce
the observed center-filled X-ray properties of G290.1-0.8, and we derive the
associated age, energy, and ambient density conditions implied by the models.
We find that for reasonable values of the explosion energy, the remnant age is
of order (1 - 2) x 10^{4} yr. This places a fairly strong constraint on any
association between G290.1-0.8 and PSR J1105-610, which would require an
anomalously large velocity for the pulsar.


title: On the Distribution of Orbital Poles of Milky Way Satellites

abstract:
  In numerous studies of the outer Galactic halo some evidence for accretion
has been found. If the outer halo did form in part or wholly through merger
events, we might expect to find coherent streams of stars and globular clusters
following similar orbits as their parent objects, which are assumed to be
present or former Milky Way dwarf satellite galaxies. We present a study of
this phenomenon by assessing the likelihood of potential descendant ``dynamical
families'' in the outer halo. We conduct two analyses: one that involves a
statistical analysis of the spatial distribution of all known Galactic dwarf
satellite galaxies (DSGs) and globular clusters, and a second, more specific
analysis of those globular clusters and DSGs for which full phase space
dynamical data exist. In both cases our methodology is appropriate only to
members of descendant dynamical families that retain nearly aligned orbital
poles today. Since the Sagittarius dwarf (Sgr) is considered a paradigm for the
type of merger/tidal interaction event for which we are searching, we also
undertake a case study of the Sgr system and identify several globular clusters
that may be members of its extended dynamical family. (ABRIDGED)


title:
An Efficient Monte Carlo Algorithm for a Restricted Class of Scattering
  Problems in Radiation Transfer

abstract:
  We describe an efficient Monte Carlo algorithm for a restricted class of
scattering problems in radiation transfer. This class includes many
astrophysically interesting problems, including the scattering of ultraviolet
and visible light by grains. The algorithm correctly accounts for
multiply-scattered light. We describe the algorithm, present a number of
important optimizations, and explicity show how the algorithm can be used to
estimate quantities such as the emergent and mean intensity. We present two
test cases, examine the importance of the optimizations, and show that this
algorithm can be usefully applied to optically-thin problems, a regime
sometimes considered limited to explicit single-scattering plus attenuation
approximations.


title:
Chandra Observation of MS 1455.0+2232: cold fronts in a massive cooling
  flow cluster?

abstract:
  We present the Chandra observation of the cluster of galaxies MS 1455.0+2232.
  From previous ASCA and ROSAT observations, this cluster was identified as a
``relaxed'' cluster that hosts one of the most massive cooling flows detected.
With higher angular resolution, the Chandra X-ray image shows the presence of
two surface brightness edges on opposite sides of the X-ray peak: the first at
190 kpc to the north and the second at 450 kpc to the south. Even though the
low exposure of this observation limits our ability to constrain the
temperature jump across both edges, we show that the northern edge is likely to
be a ``cold front'' similar to others observed recently by Chandra in the
clusters A2142, A3667, RX J1720.1+2638, and A2256. The observed cold front is
most likely produced by the motion, from south to north, of a group-size dark
matter halo. The most natural explanation for the presence of this observed
moving subclump is that MS 1455.0+2232 is a merger cluster in the very last
stage before it becomes fully relaxed. This scenario, however, appears to be
unlikely as the cluster shows no further sign of ongoing merger. Moreover, it
is not clear if a massive cooling flow could have survived this kind of merger.
We propose an alternative scenario in which, as for RX J1720.1+2638, MS
1455.0+2232 is the result of the hierarchical collapse of two co-located
density perturbations, the first a group-scale perturbation collapse followed
by a second cluster-scale perturbation collapse that surrounded, but did not
destroy, the first. We suggest that a cooling flow may have begun inside the
already collapsed group-scale perturbation and may have been later amplified by
the gas compression induced by the infall of the overlying main cluster mass.


title: Millenium Year X-ray Transients in Andromeda Galaxy

abstract:
  We study three transient X-ray sources, that were bright in the central
region of M31 galaxy in the year 2000. Observations with Chandra and XMM-Newton
allowed us for the first time in the history of X-ray astronomy, to build light
curves of transient sources in M31 suitable for studying their variability on a
time scale of months and, in some periods, weeks. The three sources demonstrate
distinctly different types of X-ray variability and spectral evolution. XMMU
J004234.1+411808 is most likely a black hole candidate based on the similarity
of its X-ray light curve and spectra to typical transient low-mass X-ray
binaries observed in our Galaxy. The outburst of CXO J004242.0+411608 lasted
longer than a year, which makes the source an unusual X-ray transient. The
supersoft transient XMMU J004319.4+ 411759 is probably a classical nova-like
system containing a magnetized, rapidly-spinning white dwarf. We estimate a
total rate of X-ray transient outbursts in the central bulge of M31 to be of
the order ~10 per year. The rate of the hard X-ray transients (~5 1/year) in
the central part of the Andromeda Galaxy appears to be comparable to that of
the central part of our own Galaxy.


title: VERITAS: the Very Energetic Radiation Imaging Telescope Array System

abstract:
  The Very Energetic Radiation Imaging Telescope Array System (VERITAS)
represents an important step forward in the study of extreme astrophysical
processes in the universe. It combines the power of the atmospheric Cherenkov
imaging technique using a large optical reflector with the power of
stereoscopic observatories using arrays of separated telescopes looking at the
same shower. The seven identical telescopes in VERITAS, each of aperture 10 m,
will be deployed in a filled hexagonal pattern of side 80 m; each telescope
will have a camera consisting of 499 pixels with a field of view of 3.5 deg
VERITAS will substantially increase the catalog of very high energy (E >
100GeV) gamma-ray sources and greatly improve measurements of established
sources.


title: Simulating the X-ray Forest in a Lambda CDM Universe

abstract:
  Numerical simulations predict that a large number of baryons reside in
intergalactic space at temperatures between 10^5-10^7 K. Highly-ionized metals,
such as O VII and O VIII, are good tracers of this ``warm-hot intergalactic
medium'', or WHIM. For collisionally-ionized gas, the ionization fraction of
each ion peaks at some particular temperature (``peak temperatures''), so
different ions can therefore trace the IGM at different temperatures. We
performed a hydrodynamic simulation to study the metal distributions in the
IGM. By studying the distribution functions of H- and He-like O, Si and Fe in a
collisionally-ionized IGM and comparing with semi-analytic results based on the
Press-Schechter formalism, we find: (1) ions with higher peak temperatures (for
instance, Fe XXVI) tend to concentrate around virialized halos, which can be
well described by the Press-Schechter distribution, ions with lower peak
temperatures are found both in small halos (such as groups of galaxies) and in
filaments; (2) lower peak temperature ions are more abundant and should be
easily observed; (3) peculiar velocities contribute a significant part to the
broadening of the resonant absorption lines.


title: A Solution to the Missing Link in the Press-Schechter Formalism

abstract:
  The Press-Schechter (PS) formalism for mass functions of the gravitationally
collapsed objects is reanalyzed. It has been suggested by many authors that the
PS mass function agrees well with the mass function given by $N$-body
simulations, while many too simple assumptions are contained in the formalism.
In order to understand why the PS formalism works well we consider the
following three effects on the mass function: the filtering effect of the
density fluctuation field, the peak ansatz in which objects collapse around
density maxima, and the spatial correlation of density contrasts within a
region of a collapsing halo because objects have non-zero finite volume.
According to the method given by Yano, Nagashima & Gouda (YNG) who used an
integral formula proposed by Jedamzik, we resolve the missing link in the PS
formalism, taking into account the three effects. While YNG showed that the
effect of the spatial correlation alters the original PS mass function, in this
paper, we show that the filtering effect almost cancels out the effect of the
spatial correlation and that the original PS is almost recovered by combining
these two effects, particularly in the case of the top-hat filter. On the other
hand, as for the peak ansatz, the resultant mass functions are changed
dramatically and not in agreement especially at low-mass tails in the cases of
the Gaussian and the sharp $k$-space filters. We show that these properties of
the mass function can be interpreted in terms of the kernel probability
$P(M_{1}| M_{2})$ in the integral formula qualitatively.


title:
X-ray Properties of the Central kpc of AGN and Starbursts: The Latest
  News from Chandra

abstract:
  The X-ray properties of 15 nearby (v<3,000 km/s) galaxies that possess AGN
and/or starbursts are discussed. Two-thirds have nuclear extended emission on
scales from ~0.5 to ~1.5 kpc that is either clearly associated with a nuclear
outflow or morphologically resembles an outflow. Galaxies that are
AGN-dominated tend to have linear structures while starburst-dominated galaxies
tend to have plume-like structures. Significant X-ray absorption is present in
the starburst regions, indicating that a circumnuclear starburst is sufficient
to block an AGN at optical wavelengths. Galaxies with starburst activity
possess more X-ray point sources within their central kpc than non-starbursts.
Many of these sources are more luminous than typical X-ray binaries. The
Chandra results are discussed in terms of the starburst-AGN connection, a
revised unified model for AGN, and possible evolutionary scenarios.


title:
A Radiation-Hydrodynamical Model for Supermassive Black Hole-to-Bulge
  Mass Relation and Quasar Formation

abstract:
  As a potential mechanism to build up supermassive black holes (BHs) in a
spheroidal system, we consider the radiation drag effect by bulge stars, which
extracts angular momentum from interstellar gas and thus allows the gas to
accrete onto the galactic center. With incorporating radiation hydrodynamical
equation with simple stellar evolution, it is shown that the BH-to-bulge mass
ratio, $f_{BH}$, is basically determined by a fundamental constant, that is,
the energy conversion efficiency for nuclear fusion of hydrogen to helium,
$\epsilon=0.007$. More specifically, $f_{BH}$ is predicted to be $0.3\epsilon
-0.5\epsilon$. Based on the present model for BH growth, a scenario for quasar
formation is addressed in relation to ultraluminous infrared galaxies.


title: Untangling the merger history of massive black holes with LISA

abstract:
  Binary black hole coalescences emit gravitational waves that will be
measurable by the space-based detector it LISA to large redshifts. This
suggests that LISA may be able to observe black holes grow and evolve as the
universe evolves, mapping the distribution of black hole masses as a function
of redshift. An immediate difficulty with this idea is that LISA measures
certain redshifted combinations of masses with good accuracy: if a system has
some mass parameter m, then LISA measures (1+z)m. This mass-redshift degeneracy
makes it difficult to follow the mass evolution. In many cases, LISA will also
measure the luminosity distance D of a coalescence accurately. Since
cosmological parameters (particularly the mean density, the cosmological
constant, and the Hubble constant) are now known with moderate precision, we
can obtain z from D and break the degeneracy. This makes it possible to
untangle the mass and redshift and to study the mass and merger history of
black holes. Mapping the black hole mass distribution could open a window onto
an early epoch of structure formation.


title: Instability of an accretion disk with a magnetically driven wind

abstract:
  We present a linear analysis of the stability of accretion disks in which
angular momentum is removed by the magnetic torque exerted by a centrifugally
driven wind. The effects of the dependence of the wind torque on field strength
and inclination, the sub-Keplerian rotation due to magnetic forces, and the
compression of the disk by the field are included. A WKB dispersion relation is
derived for the stability problem. We find that the disk is always unstable if
the wind torque is strong. At lower wind torques instability also occurs
provided the rotation is close to Keplerian. The growth time scale of the
instability can be as short as the orbital time scale. The instability is
mainly the result of the sensitivity of the mass flux to changes in the
inclination of the field at the disk surface. Magnetic diffusion in the disk
stabilizes if the wind torque is small.


title:
Correlation of the magnetic field and the intra-cluster gas density in
  galaxy clusters

abstract:
  We present a correlation between X-ray surface brightness and Faraday
rotation measure in galaxy clusters, both, from radio and X-ray observations as
well as from modeling of the intra-cluster medium. The observed correlation
rules out a magnetic field of constant strength throughout the cluster.
Cosmological, magneto-hydrodynamic simulations of galaxy clusters are used to
show that for a magnetic field of cosmic origin this correlation is expected
and excellently reproduces the observations showing that the RMS scatter of the
Faraday rotation increases linearly with the X-ray surface brightness. From the
correlation between the observable quantities, rotation measure and X-ray
surface brightness, we infer a relation between the physical quantities:
magnetic field and gas density. For the best available observations, those of
A119, we find $B \propto n_e^{0.9}$.


title: Simulation of radio plasma in clusters of galaxies

abstract:
  We present three-dimensional hydrodynamical simulations of buoyant gas in a
typical cluster environment. The hot matter was injected continuously into a
small region off-set from the cluster centre. In agreement with previous
analytic estimates we found that the bubbles evolve very differently depending
on their luminosity. Using tracer particles we computed radio maps of the
bubbles based on different assumptions about the magnetic field. In the radio
band the bubbles closely resemble FRI sources. For the bubbles to be detectable
for long enough to account for FRI sources, we found that reacceleration has to
take place. The bubbles are generally difficult to detect, both, in the radio
and in the X-ray band. Thus it is possible to hide a significant amount of
energy in the form of bubbles in clusters. Finally, we compute the efficiency
of the bubbles to stir the ICM and find that recurrent low-power sources may be
fairly effective in mixing the inner cluster region.


title: Revisiting the Open Cluster M35

abstract:
  We present a photometric and spectroscopic study of the young open cluster
M35, including very deep and accurate photometry of the stellar (including
white dwarfs) and substellar population of the cluster, a complete mass
function, rotational and radial velocities, and lithium abundances.


title: Tracing luminous and dark matter with the Sloan Digital Sky Survey

abstract:
  I summarize the scientific goals and current status of the Sloan Digital Sky
Survey, briefly describe the Early Data Release, and discuss some recent
scientific results obtained from commissioning data which are apposite to the
distribution of luminous and dark matter in the Universe.


title:
Discovery of X-ray Pulsations from the Compact Central Source in the
  Supernova Remnant 3C 58

abstract:
  We report on high time resolution observations of the SNR 3C 58 using the
High Resolution Camera on the Chandra X-ray Observatory. These data show a
point-like central source, from which we detect 65.68 ms pulsations at 6.7
sigma significance. We interpret these pulsations as corresponding to a young
rotation-powered pulsar (PSR J-205+6449) which is associated with, and powers,
3C 58. Analysis of archival RXTE data from three years earlier confirms these
pulsations, and allows us to determine a spin-down rate of P-dot=1.93x10^-13
s/s. Assuming a magnetic dipole model for PSR J0205+6449, we infer a surface
magnetic field of 3.6x10^12 G. The characteristic age for this pulsar is 5400
yr, indicating either that 3C 58 was not the supernova of 1181 CE, or that the
pulsar's initial spin period was ~60 ms.


title: ASCA Observations of the Central Regions of M31

abstract:
  Using ASCA, spatially integrated X-ray spectra of the central regions of M31
were studied. Data were accumulated over three different circular regions, with
the radii of 3', 6' and 12', all centered on the nucleus. The spectra are
relatively similar among the three regions. In the energy range above 1.5 keV,
the spectra are reproduced by a combination of a disk black-body component and
a black-body component, implying that the emission mainly comes from an
assembly of low-mass X-ray binaries. In energies below 1.5 keV, the spectra
involves two additional softer components, expressed with thin-thermal plasma
emission models of temperatures ~ 0.9 keV and ~ 0.3 keV. Over the central 12'
(2.4 kpc) region and in the 0.5-10 keV energy band, the binary component has a
luminosity of 2.6 x 10^{39} erg/s, while the two softer components both exhibit
luminosities of ~ 2 x 10^{38} erg/s. These results are compared with those from
other missions, including Chandra and XMM-Newton in particular. Discussion is
made on the nature of the two softer spectral components besides the binary
one.


title:
Submillimeter telescope for the Russian segment of the ISS:
  Submillimetron Project

abstract:
  The Submillimetron is the international project of the space telescope for
astronomical studies at the submillimeter and infrared wavelengths using
facilities of the Russian segment of the International Space Station (ISS). The
concept of the telescope includes a 60 cm mirror cooled to liquid helium
temperature with a novel type of microbolometers arrays using effects of
superconductivity. This combination gives unique possibility to realize
background limited sensitivity in the spectral minimum of the extraterrestrial
background near frequency 1 THz between peaks of galactic dust emission and
CMB. The angular resolution about 1 arcmin, field of view about 1 degree, and
optics are similar to IRAS satellite, but the sensitivity is better on more
than order of magnitude for about 10^-18 W/Hz^-1/2. This improvement and
another spectral region permits to reveal in full sky survey considerably more
new astrophysical objects. The concept of free flying instrument with periodic
docking to ISS gives possibility to combine low cost with reliability,
refilling, repairment and maintenance.


title: An irradiated accretion disk in the narrow-line Seyfert 1 RE J1034+396?

abstract:
  We model the optical to X-ray continuum spectrum of the narrow-line Seyfert 1
galaxy RE J1034+396. We show that the flat optical spectrum is consistent with
emission from an irradiated accretion disk. The X-ray emission can be modelled
with a disk blackbody and a Comptonised component. The temperature at the inner
edge of the disk T_{in} = (0.12 +/- 0.02) keV. Using this constraint, we show
that the flat optical spectrum is consistent with emission from the
irradiatively heated outer part of the accretion disk. We constrain the outer
radius of the optically thick disk (R >~ 5 x 10^{16} cm) and the inner radius
of the irradiation-dominated region (R >~ 5 x 10^{12} cm). Our optical and
X-ray spectral fits indicate a mass 0.6 <~ M <~ 3 x 10^6 M_{sun}, and do not
rule out a low (i.e. face-on) inclination angle for the system.


title: Reconstructing cosmological fields using tessellation methods

abstract:
  Astronomical observations, physical experiments as well as computer
simulations often involve discrete data sets supposed to represent a fair
sample of an underlying smooth and continuous field. Reconstructing the
underlying fields from a set of irregularly sampled data is therefore a
recurring key issue in operations on astronomical data sets. Conventional
methods involve artificial filtering through a grid or a smoothing kernel and
fail to achieve an optimal result. Here we describe a fully self-adaptive
geometric method which does not make use of artificial filtering, and which
makes optimal use of the available information.


title:
Prospects for Star Formation Studies with Mid-Infrared Instruments on
  Large Telescopes

abstract:
  Imaging and spectroscopic observations in the mid-infrared wavelength range
(5$\mu$m--30$\mu$m) offer valuable insight into the origins of stars and
planets. Sensitive new array detectors on 8-meter class telescopes make it
possible to study a wide range of phenomena, from protoplanetary disks to
starburst galaxies, in unprecedented detail. I review the capablities of
ground-based mid-infrared instruments (e.g., high spatial resolution) and their
limitations (e.g., poor sensitivity, small field of view) using several
examples in the field of star formation, and discuss prospects for the near
future.


title: Simulating the X-ray Forest

abstract:
  Numerical simulations predict that a large number of baryons reside in
intergalactic space at temperatures between 10^5-10^7 K. Highly-ionized metals,
such as O VII and O VIII, are good tracers of this ``warm-hot intergalactic
medium'', or WHIM. For collisionally-ionized gas, the ionization fraction of
each ion peaks at some particular temperature (``peak temperatures''), so
different ions can therefore trace the IGM at different temperatures. We
performed a hydrodynamic simulation to study the metal distributions in the
IGM. We then draw random lines-of-sight across the simulated region and
synthesize resonance absorption line spectra in a similar way to simulating the
Ly-alpha forest. By studying the distribution functions of H- and He-like O, Si
and Fe in a collisionally-ionized IGM and comparing with semi-analytic results
based on the Press-Schechter formalism, we find: (1) ions with higher peak
temperatures (for instance, Fe XXVI) tend to concentrate around virialized
halos, which can be well described by the Press-Schechter distribution, ions
with lower peak temperatures are found both in small halos (such as groups of
galaxies) and in filaments; (2) lower peak temperature ions are more abundant
and should be easily observed; (3) peculiar velocities contribute a significant
part to the broadening of the resonant absorption lines.


title: X-Ray spectra from accretion disks illuminated by protons

abstract:
  The X-ray spectrum from a cool accretion disk heated by virialized protons is
computed. The cool disk is either embedded in a magnetically heated accretion
disk corona or partly extends into an ion supported torus (or ADAF). We
calculate the stationary equilibrium between proton heating, electron thermal
conduction and the radiative losses by bremsstrahlung and Compton scattering. A
heated surface layer on top of the accretion disk is produced with temperatures
between 60--90 keV above a cool layer with temperatures of 0.01 keV (AGN) and
1keV (galactic black hole candidates). The spectra produced by the surface
layer are reminiscent of hard state spectra, but a bit too steep, especially
for AGN's. Near the inner edge of the disk, where the optical depth of the disk
$\tau lesssim 1$, we find that the cool component of the disk disappears.
Instead, the hot protons from the corona/ADAF heat the disk, on a dynamical
time-scale, to temperatures of several 100 keV, limited by pair production.
This region, here called a `warm disk', could contribute significantly to the
hard X-ray spectra and could be important for feeding material into an ADAF.


title: The transition from a cool disk to an ion supported flow

abstract:
  We show that the inner regions of a cool accretion disk in an X-ray binary
can transform into an advective, ion supported accretion flow (an optically
thin ADAF, here called ISAF), through events involving only the known
properties of the Coulomb interaction in a two-temperature plasma, standard
radiation processes, and viscous heating. The optically thin inner edge of the
disk is heated to a few 100 keV by the strong flux of hot ions from the
surrounding hot ISAF. We show that he resident ions in this `warm' disk are
thermally unstable due to internal viscous heating, and heat up to their virial
temperature. The innermost disk regions thus evaporate and feed the ISAF. These
processes are demonstrated with time dependent calculations of a
two-temperature plasma in vertical hydrostatic equilibrium, including heating
by external ions, internal proton--electron energy exchange, and viscous
heating. The process complements the `coronal' evaporation mechanism which
operates at larger distances from the central object.


title: Reconciling Damped Ly-alpha Statistics and 21cm Studies at z=0

abstract:
  Blind 21cm surveys in the local universe have shown that the local HI mass
density, Omega_HI, is dominated by luminous, high surface brightness, spiral
galaxies. On the other hand, surveys for host galaxies of damped Ly-alpha
systems have not always been successful in finding bright spiral galaxies. From
an analysis of 21cm aperture synthesis maps of nearby galaxies we show that
this apparent contradiction can be resolved by realizing that the HI mass
density is dominated by L* galaxies, but the HI cross section near the DLA
threshold is more evenly distributed over galaxies with a large range in
luminosity, gas mass, and surface brightness. The distributions of column
densities and impact parameters of optically identified and non-identified DLA
host galaxies in the literature and the HI maps are qualitatively in agreement.
Due to poor number statistics of low redshift DLA systems, there is no firm
indication that the redshift number count of low redshift DLA systems is
inconsistent with that calculated from the nearby galaxy population.


title: Tidal Evolution Of the Planetary System around HD 83443

abstract:
  Two planets with orbital period ratio approximately 10:1 have been discovered
around the star HD 83443. The inner and more massive planet, HD 83443b, has the
smallest semi-major axis among all currently known exoplanets. Unlike other
short period exoplanets, it maintains a substantial orbital eccentricity,
e_1=0.079+/- 0.008, in spite of efficient tidal damping. This is a consequence
of its secular interactions with HD 83443c whose orbital eccentricity
e_2=0.42+/-0.06. Dissipation, associated with tides the star raises in the
inner planet, removes energy but not angular momentum from its orbit, while
secular interactions transfer angular momentum but not energy from the inner to
the outer planet's orbit. The outward transfer of angular momentum decreases
the tidal decay rate of the inner planet's orbital eccentricity while
increasing that of the outer planet. The alignment of the apsides of the
planets' orbits is another consequence of tidal and secular interactions. In
this state the ratio of their orbital eccentricities, e_1/e_2, depends upon the
secular perturbations the planets exert on each other and on additional
perturbations that enhance the inner planet's precession rate. Tidal and
rotational distortions of the inner planet along with general relativity
provide the most important of these extra precessional perturbations, each of
which acts to reduce e_1/e_2. Provided the planets' orbits are coplanar, the
observed eccentricity ratio uniquely relates sin i and
C=(k_2/k_{2J})(R_1/R_J)^5, where the tidal Love number, k_2, and radius, R_1,
of the inner planet are scaled by their Jovian equivalents.


title: BeppoSAX Observation of the NGC 3079 Nucleus

abstract:
  Using the BeppoSAX observatory, we have observed a nearby LINER/Seyfert 2
galaxy, NGC 3079, which is known as an outflow galaxy and a bright H_2O-maser
source. Using the PDS detector, we have revealed that the NGC 3079 nucleus
suffers from a Compton-thick absorption, with a hydrogen column density \sim
10^{25} cm^{-2}. After corrected the absorption, the 2--10 keV luminosity
becomes 10^{42-43} erg s^{-1} at a distance of 16 Mpc. It is 2-3 orders of
magnitude higher than that observed in the MECS band (below 10 kev). We also
detected a strong Fe-K line at 6.4^{+0.3}_{-0.2} keV with an equivalent width
of 2.4^{+2.9}_{-1.5} keV, which is consistent with the heavy absorption.


title: Constraints on 12C(alpha,gamma)16O from White Dwarf Seismology

abstract:
  For many years, astronomers have promised that the study of pulsating white
dwarfs would ultimately lead to useful information about the physics of matter
under extreme conditions of temperature and pressure. We can now make good on
that promise. Using observational data from the Whole Earth Telescope and a new
analysis method employing a genetic algorithm, we empirically determine the
central oxygen abundance of the helium-atmosphere variable white dwarf GD 358.
We use this value, combined with detailed evolutionary calculations of the
internal chemical profiles to place constraints on the 12C(alpha,gamma)16O
nuclear reaction cross-section.


title: ASCA Observations of the Thermal Composite Supernova Remnant 3C 391

abstract:
  We present the results from ASCA observations of the centrally enhanced
supernova remnant 3C 391 (G31.9+0.0). We use the ASCA SIS data to carry out an
investigation of the spatial and spectral properties of the X-ray emission from
this remnant. The collisional equilibrium ionization and non-equilibrium
ionization spectral fits indicate that the hot gas within the remnant has
basically reached ionization equilibrium. The variation of the hydrogen column
density across the remnant is in agreement with the presence of a molecular
cloud to the northwest. The comparisons of hydrogen column and X-ray hardness
between the NW and SE portions of the remnant support a scenario in which the
SNR has broken out of a dense region into an adjacent region of lower density.
The mean density within the SNR is observed to be much lower than the immediate
ambient cloud density. This and the centrally brightened X-ray morphology can
be explained either by the evaporation of engulfed cloudlets or by a radiative
stage of evolution for the remnant.


title: Period distribution of old accreting isolated neutron stars

abstract:
  In this paper we present calculations of period distribution for old
accreting isolated neutron stars (INSs). After few billion years of evolution
low velocity INSs come to the stage of accretion. At this stage INS's period
evolution is governed by magnetic braking and angular momentum accreted. Since
the interstellar medium is turbulized accreted momentum can either accelerate
or decelerate spin of an INS, therefore the evolution of period has chaotic
character.
  Our calculations show that in the case of constant magnetic field accreting
INSs have relatively long spin periods (some hours and more, depending on INS's
spatial velocity, its magnetic field and density of the surrounding medium).
Such periods are much longer than the values measured by {\emph ROSAT} for 3
radio-silent isolated neutron stars. Due to long periods INSs should have high
spin up/down rates, $\dot p$, which should fluctuate on a time scale of $\sim
1$ yr.


title: Multiple stellar population in the Sextans dwarf spheroidal galaxy?

abstract:
  We present wide field (33 X 34 arcmin^2) multiband (BVI) CCD photometry (down
to I <= 20.5) of the very low surface brightness dwarf Spheroidal (dSph) galaxy
Sextans. In the derived Color Magnitude Diagrams we have found evidences
suggesting the presence of multiple stellar populations in this dSph. In
particular we discovered: {\it (i)} a Blue Horizontal Branch (HB) tail that
appears to lie on a brighter sequence with respect to the prominent Red HB and
the RR Lyrae stars, very similar to what found by Majewski et al. (1999) for
the Sculptor dSph; {\it (ii)} hints of a bimodal distribution in color of the
RGB stars; {\it (iii)} a double RGB-bump. All these features suggest that (at
least) two components are present in the old stellar population of this galaxy:
a main one with [Fe/H]~ -1.8 and a minor component around [Fe/H]<~ -2.3. The
similarity with the Sculptor case may indicate that multiple star formation
episodes are common also in the most nearby dSphs that ceased their star
formation activity at very early epochs.


title: Cuspy Dark-Matter Haloes and the Galaxy

abstract:
  The microlensing optical depth to Baade's Window constrains the minimum total
mass in baryonic matter within the Solar circle to be greater than 3.9 x
10^{10} solar masses, assuming the inner Galaxy is barred with viewing angle of
roughly 20 degrees. From the kinematics of solar neighbourhood stars, the local
surface density of dark matter is about 30 +/- 15 solar masses per square
parsec. We construct cuspy haloes normalised to the local dark matter density
and calculate the circular-speed curve of the halo in the inner Galaxy. This is
added in quadrature to the rotation curve provided by the stellar and ISM
discs, together with a bar sufficiently massive so that the baryonic matter in
the inner Galaxy reproduces the microlensing optical depth. Such models violate
the observational constraint provided by the tangent-velocity data in the inner
Galaxy (typically at radii 2-4 kpc). The high baryonic contribution required by
the microlensing is consistent with implications from hydrodynamical modelling
and the pattern speed of the Galactic bar. We conclude that the cuspy haloes
favoured by the Cold Dark Matter cosmology (and its variants) are inconsistent
with the observational data on the Galaxy.


title:
The pulse phase-dependent spectrum of the anomalous X-ray pulsar 1RXS
  J170849-400910

abstract:
  We report on the results of a 50ks BeppoSAX observation of 1RXS
J170849-400910, one of the five (plus a candidate) known anomalous X-ray
pulsars. The BeppoSAX data are consistent with a power-law plus blackbody
spectral decomposition, making 1RXS J170849-400910 the fourth source of this
class for which such a spectral decomposition was found. The inferred power-law
slope and blackbody temperature are Gamma~2.6 and kT_BB~0.46keV, respectively.
We found significant energy-dependence of the pulse profile, a remarkable
feature for an AXP. By using the power-law plus blackbody decomposition we
detected a significant variation in at least one spectral parameter, the
power-law photon index, as a function of the pulse phase. This is the first
significant detection of spectral parameter variation in an AXP. The
implications of these results are briefly discussed.


title:
VHE Neutrinos and Gamma-Rays as Probes for Anisotropy of Arrival
  Directions of EeV Cosmic Rays

abstract:
  We estimate the fluxes of very high energy (VHE) gamma-rays and neutrinos
from the Galactic Center which are by-products of the hadronic interactions
between primary protons which are accelerated up to $\sim 10^{19}$eV and
ambient matter. We find that these signals depend strongly on the spectrum
index of the primary protons. This means that detection of these signals from
the Galactic Center will constrain the spectrum of the primary particles,
which, in turn, should constrain the acceleration mechanism at the Galactic
Center. We show that GeV-TeV gamma-rays will be detected by the ground-based
Cherenkov telescopes such as CANGAROOIII and the next-generation satellites
such as GLAST. Thus the acceleration region of the CRs below $\sim 10^{19}$eV
will be determined accurately by gamma-ray telescopes, which should help our
understanding on the particle acceleration. We estimate the event rate of VHE
neutrinos for the planned 1 km$^{2}$ detectors such as IceCube, ANTARES and
NESTOR. The event rate also depends on the spectrum index of the primary
protons. In the optimistic case, the event rate amounts to $\sim 10^4$ events
per year and the signals from the Galactic Center dominate the atmospheric
neutrino background.


title: The complex iron line of NGC 5506

abstract:
  The bright Narrow Emission Line Galaxy, NGC 5506, has been observed
simultaneously by XMM-Newton and BeppoSAX. The iron line is complex, with at
least two components: one narrow and corresponding to neutral iron, the second
one broad and corresponding to ionized iron. The latter line is equally well
fitted by a truly broad line or by a blend of He- and H-like narrow lines. The
bulk of the Compton reflection continuum originates in neutral matter, and is
therefore associated with the narrow line: they are most likely emitted in
distant matter. The origin of the ionized line(s) is less certain, but the
solution in terms of a blend of narrow lines from photoionized matter seems to
be preferable to emission from an ionized, relativistic accretion disc.


title: Jet Formation and Collimation in AGN and microQuasars

abstract:
  We briefly review our current understanding for the formation, acceleration
and collimation of winds to jets associated with compact astrophysical objects
such as AGN and microQuasars.


title: NGC 5775: anatomy of a disk-halo interface

abstract:
  We present the first high-resolution study of the disk-halo interface in an
edge-on galaxy (NGC 5775) in which every component of the interstellar medium
is represented and resolved. New single-dish CO J=2-1 and CO J=1-0 data, ROSAT
X-ray data, and HIRES IRAS data are presented along with HI data which
emphasizes the high latitude features. In conjunction with previously published
radio continuum (6 and 20 cm) and H alpha data, we find spatial correlations
between various ISM components in that all components of the ISM are present in
the disk-halo features (except for CO for which there is insufficient spatial
coverage). The HI features extend to about 7 kpc above the plane. In one case,
a loop is detected in position-velocity space, and are also observed over a
large velocity range. This implies that the disk-halo features represent
expanding supershells. However, the shells may be incomplete and partially
open-topped, suggesting that we are observing the breakup of the supershells as
they traverse the disk-halo interface. There is some evidence for acceleration
with z height and both redshifted and blueshifted velocities are present,
although the gas which is lagging with respect to galactic rotation dominates.
The radio continuum spectral index is flatter around the shell rims, suggesting
that shocks may be important in these regions (thermal contribution can not
account for this flattening). The H alpha emission is located interior to the
HI. For feature F3, the H alpha emission forms the interior "skin" of the HI
shell, yet there appears to be a minimum of in-disk star formation immediately
below the feature. We present a picture of a "typical" HI supershell which
accelerates and breaks up through the disk-halo interface. Such a feature is
likely internally generated via an energetic event in the disk.


title:
Screw instability in black hole magnetospheres and a stabilizing effect
  of field-line rotation

abstract:
  The screw instability of magnetic field is a mechanism for prohibiting a
generation of strongly twisted field lines in large scales. If it can work in
black hole magnetospheres, the global axisymmetric structure and the main
process of energy release will be significantly influenced. In this paper, we
study the instability condition in the framework of the variational principle,
paying special attention to a stabilizing effect due to field-line rotation
against the screw-unstable modes satisfying the well-known Kruskal-Shafranov
criterion. The basic formulation for the stability analysis of rotating
force-free fields in Kerr geometry is provided. Then, for the practical use of
the analytical method, the stationary configuration is assumed to be
cylindrical, and we treat the long-wave mode perturbations excited at large
distances from the central black hole, where the strength of gravity becomes
negligibly small. This allows us to derive clearly the new criterion dependent
on the rotational angular velocity of magnetic field lines, and the
implications of the results obtained for magnetic activities of jets driven by
a black hole are briefly discussed.


title: Primordial molecules at millimeter wavelengths

abstract:
  Chemistry plays a particular role in astrophysics. After atomic hydrogen,
helium and their ions, the Universe probably contains more mass in molecules
than in any other species. Molecule formation in the early, pre-galactic
  Universe may have had much to do with the formation of galaxies themselves.
In this context the possible interaction between primordial molecules and
photons of the Cosmic Microwave Background is very important through the
theoretical perspectives and constraints which could give some information on
the theory of the large scale structure formation. In this paper we recall the
more recent progresses on the chemistry of the early Universe, and describe the
importance of molecules in the formation phase of proto objects. A special
attention is done concerning the {\it case of LiH.


title:
Abundant Molecular Gas in Tidal Dwarf Galaxies: On-going Galaxy
  Formation

abstract:
  [Abridged...] We investigate the process of galaxy formation as can be
observed in the only currently forming galaxies -- the so-called Tidal Dwarf
Galaxies, hereafter TDGs -- through observations of the molecular gas detected
via its CO emission. These objects are formed of material torn off of the outer
parts of a spiral disk due to tidal forces in a collision between two massive
galaxies. Molecular gas is a key element in the galaxy formation process,
providing the link between a cloud of gas and a bona fide galaxy. We have
detected CO in 8 TDGs (two of them have already been published in Braine et al.
2000), with an overall detection rate of 80%, showing that molecular gas is
abundant in TDGs, up to a few 10^8 M_sun. The CO emission coincides both
spatially and kinematically with the HI emission, indicating that the molecular
gas forms from the atomic hydrogen where the HI column density is high. A
possible trend of more evolved TDGs having greater molecular gas masses is
observed, in accord with the transformation of HI into H2.... Although higher
spatial resolution CO (and HI) observations would help reduce the
uncertainties, we find that TDGs require no dark matter, which would make them
the only galaxy-sized systems where this is the case. Dark matter in spirals
should then be in a halo and not a rotating disk. Most dwarf galaxies are dark
matter-rich, implying that they are not of tidal origin....


title: The HELLAS2XMM survey: I. The X-ray data and the Log(N)-Log(S)

abstract:
  We present the first results from an XMM-Newton serendipitous medium-deep
survey, which covers nearly three square degrees. We detect a total of 1022,
495 and 100 sources, down to minimum fluxes of about 5.9 x 10^-16, 2.8 x 10^-15
and 6.2 x 10^-15 erg cm^-2 s^-1, in the 0.5-2, 2-10 and 4.5-10 keV band,
respectively. In the soft band this is one of the largest samples available to
date and surely the largest in the 2-10 keV band at our limiting X-ray flux.
The measured Log(N)-Log(S) are found to be in good agreement with previous
determinations. In the 0.5-2 keV band we detect a break at fluxes around 5 x
10^-15 erg cm^-2 s^-1. In the harder bands, we fill in the gap at intermediate
fluxes between deeper Chandra and XMM-Newton observations and shallower
BeppoSAX and ASCA surveys.


title:
Big Bang Nucleosynthesis, Cosmic Microwave Background Anisotropies and
  Dark Energy

abstract:
  Over the last decade, cosmological observations have attained a level of
precision which allows for very detailed comparison with theoretical
predictions. We are beginning to learn the answers to some fundamental
questions, using information contained in Cosmic Microwave Background
Anisotropy (CMBA) data. In this talk, we briefly review some studies of the
current and prospected constraints imposed by CMBA measurements on the neutrino
physics and on the dark energy. As it was already announced by Scott (1999), we
present some possible "new physics" from the Cosmic Microwave Background.


title:
Exo-planet detection with the COROT space mission. I. A multi-transit
  detection criterion

abstract:
  We present a detection criterion for exo-planets to be used with the space
mission COROT. This criterion is based on the transit method, which suggests
the observation of star dimming caused by partial occulations by planetary
companions. When at least three transits are observed, we show that a
cross-correlation technique can yield a detection threshold, thus enabling the
evaluation of the number of possible detections, assuming a model for the
stellar population in the Galaxy.


title: Robustness of the Quintessence Scenario in Particle Cosmologies

abstract:
  We study the robustness of the quintessence tracking scenario in the context
of more general cosmological models that derive from high-energy physics. We
consider the effects of inclusion of multiple scalar fields, corrections to the
Hubble expansion law (such as those that arise in brane cosmological models),
and potentials that decay with expansion of the Universe. We find that in a
successful tracking quintessence model the average equation of state must
remain nearly constant. Overall, the conditions for successful tracking become
more complex in these more general settings. Tracking can become more fragile
in presence of multiple scalar fields, and more stable when temperature
dependent potentials are present. Interestingly though, most of the cases where
tracking is disrupted are those in which the cosmological model is itself
non-viable due to other constraints. In this sense tracking remains robust in
models that are cosmologically viable.


title: A Robotic Wide-Angle H-Alpha Survey of the Southern Sky

abstract:
  We have completed a robotic wide-angle imaging survey of the southern sky
(declination less than +15 degrees) at 656.3 nm wavelength, the H-alpha
emission line of hydrogen. Each image of the resulting Southern H-Alpha Sky
Survey Atlas (SHASSA) covers an area of the sky 13 degrees square at an angular
resolution of approximately 0.8 arcminute, and reaches a sensitivity level of 2
rayleigh (1.2 x 10^-17 erg cm^-2 s^-1 arcsec^-2) per pixel, corresponding to an
emission measure of 4 cm^-6 pc, and to a brightness temperature for microwave
free-free emission of 12 microkelvins at 30 GHz. Smoothing over several pixels
allows features as faint as 0.5 rayleigh to be detected.


title: The southern dust pillars of the Carina Nebula

abstract:
  We present preliminary results from a detailed study towards four previously
detected bright mid-infrared sources in the southern part of the Carina Nebula:
G287.73--0.92, G287.84--0.82, G287.93--0.99 and G288.07--0.80. All of these
sources are located at the heads of giant dust pillars that point towards the
nearby massive star cluster, Trumpler 16. It is unclear if these pillars are
the prime sites for a new generation of triggered star formation or if instead
they are the only remaining parts of the nebula where ongoing star fromation
can take place.


title: Non-hydrostatic gas in the core of the relaxed galaxy cluster A1795

abstract:
  Chandra data on A1795 reveal a mild edge-shaped discontinuity in the gas
density and temperature in the southern sector of the cluster at r=60/h kpc.
The gas inside the edge is 1.3-1.5 times denser and cooler than outside, while
the pressure is continuous, indicating that this is a "cold front", the surface
of contact between two moving gases. The continuity of the pressure indicates
that the current relative velocity of the gases is near zero, making the edge
appear to be in hydrostatic equilibrium. However, a total mass profile derived
from the data in this sector under the equilibrium assumption, exhibits an
unphysical jump by a factor of 2, with the mass inside the edge being lower. We
propose that the cooler gas is "sloshing" in the cluster gravitational
potential well and is now near the point of maximum displacement, where it has
zero velocity but nonzero centripetal acceleration. The distribution of this
non-hydrostatic gas should reflect the reduced gravity force in the
accelerating reference frame, resulting in the apparent mass discontinuity.
Assuming that the gas outside the edge is hydrostatic, the acceleration of the
moving gas can be estimated from the mass jump, a ~ 800 h km/s/(10^8 yr). The
gravitational potential energy of this gas that is available for dissipation is
about half of its current thermal energy. The length of the cool filament
extending from the cD galaxy (Fabian et al.) may give the amplitude of the gas
sloshing, 30-40/h kpc. Such gas bulk motion might be caused by a disturbance of
the central gravitational potential by past subcluster infall.


title: Kinematics of the Narrow-Line Region in the Seyfert 2 Galaxy Mrk 3

abstract:
  We present measurements of radial velocities for the narrow-line region gas
(NLR) in the Seyfert 2 galaxy Mrk 3 out to ~1 kpc from the nucleus. The
observations consist of two datasets, both using the Space Telescope Imaging
Spectrograph on board the Hubble Space Telescope: 1) An [O III] slitless
spectrum with the G430M grating of the inner 3" around the nucleus, and 2) a
long-slit observation centered on the nucleus (PA = 71 deg) using the G430L
grating and the 52" x 0".1 aperture. Our results produce radial velocity maps
of the emission-line gas. These maps indicate general trends in the gas motion,
which include: blueshifts and redshifts on either side of the nucleus, steep
velocity rises from systemic up to ~ +/-700 km/s taking place in the inner 0".3
(0.8 kpc) both east and west of the nucleus, gradual velocity descents back to
near-systemic values from 0".3-1".0, slightly uneven velocity amplitudes on
each side of the nucleus, and narrow velocity ranges over the entire observed
region. When fitted to kinematic modeling programs for the NLR gas, the data
clearly favor a model where the gas exists in a partially filled bicone, is
accelerated radially away from the nucleus, and is followed by a constant
deceleration. This geometry and general kinematic model is in agreement with
previous work done on the NLR gas of NGC 1068 and NGC 4151. On scales of
hundreds of parsecs, we conclude that radial outflow may be a common feature of
Seyfert galaxies.


title: Optical Flashes Preceding GRBs

abstract:
  Only one optical flash associated with a gamma-ray burst has been detected so
far by ROTSE. There are also upper limits obtained by several groups for
several bursts. Recent model calculations indicate a possibility that optical
flash may precede the main GRB. Such flashes are undetectable in the currently
popular observing mode, with optical instruments responding to GRB triggers.
There is a need to develop all sky optical monitoring system capable of
recognizing flashes in real time, and more powerful instruments that could
respond robotically to optical triggers and carry out follow up observations.


title: Chandra Observations of Nearby Spiral Galaxies

abstract:
  Chandra is revolutionising our understanding of the X-ray emission from
spiral galaxies. Before Chandra, detailed extragalactic studies were limited to
Local Group galaxies. We are now able to obtain detailed inventories of sources
in galaxies outside the Local Group, allowing population studies for the first
time. In this review I will first discuss some intriguing observations of
globular cluster sources in M31, then move outside the Local Group and
summarise the observational properties of sources in several spiral galaxies
(both bulge dominated and disk dominated). The X-ray colors and variability
characteristics suggest that most of these sources are accreting binaries. High
mass X-ray binaries are formed preferentially in disk galaxies. Finally, I show
that the luminosity functions of spiral galaxies can be qualitatively
understood in terms of simple population models.


title:
The Halo Occupation Distribution: Towards an Empirical Determination of
  the Relation Between Galaxies and Mass

abstract:
  We investigate galaxy bias in the framework of the ``Halo Occupation
Distribution'' (HOD), which defines the bias of a population of galaxies by the
conditional probability P(N|M) that a dark matter halo of virial mass M
contains N galaxies, together with prescriptions that specify the relative
spatial and velocity distributions of galaxies and dark matter within halos. By
populating the halos of a cosmological N-body simulation using a variety of HOD
models, we examine the sensitivity of different galaxy clustering statistics to
properties of the HOD. The galaxy correlation function responds to different
aspects of P(N|M) on different scales. Obtaining the observed power-law form of
xi(r) requires rather specific combinations of HOD parameters, implying a
strong constraint on the physics of galaxy formation; the success of numerical
and semi-analytic models in reproducing this form is entirely non-trivial.
Other clustering statistics such as the galaxy-mass correlation function, the
bispectrum, the void probability function, the pairwise velocity dispersion,
and the group multiplicity function are sensitive to different combinations of
HOD parameters and thus provide complementary information about galaxy bias. We
outline a strategy for determining the HOD empirically from redshift survey
data. This method starts from an assumed cosmological model, but we argue that
cosmological and HOD parameters will have non-degenerate effects on galaxy
clustering, so that a substantially incorrect cosmological model will not
reproduce the observations for any choice of HOD. Empirical determinations of
the HOD as a function of galaxy type from the 2dF and SDSS redshift surveys
will provide a detailed target for theories of galaxy formation, insight into
the origin of galaxy properties, and sharper tests of cosmological models.


title:
An inverse Compton scattering (ICS) model of pulsar emission: II.
  frequency behavior of pulse profiles

abstract:
  The shapes of pulse profiles, especially their variations with respect to
observing frequencies, are very important to understand emission mechanisms of
pulsars, while no previous attempt has been made in interpreting the
complicated phenomenology. In this paper, we present theoretical simulations
for the integrated pulse profiles and their frequency evolution within the
framework of the inverse Compton scattering (ICS) model proposed by Qiao (1988)
and Qiao & Lin (1998). Using the phase positions of the pulse components
predicted by the ``beam-frequency figure'' of the ICS model, we present
Gaussian fits to the multi-frequency pulse profiles for some pulsars. It is
shown that the model can reproduce various types of the frequency evolution
behaviors of pulse profiles observed.


title:
Distributed Data Acquisition System for Pachmarhi Array of Cerenkov
  Telescopes

abstract:
  Pachmarhi Array of \v Cerenkov Telescopes (PACT) consists of a 5$\times$5
array of \v Cerenkov telescopes deployed over an area of 100 $m$ $\times$ 80
$m$, in the form of a rectangular matrix. The experiment is based on
atmospheric \v Cerenkov technique using wavefront sampling technique. Each
telescope consists of 7 parabolic mirrors mounted para-axially on an equatorial
mount. At the focus of each mirror a fast phototube is mounted. In this
experiment a large number of parameters have to be measured and recorded from
each of the 175 phototubes in the shortest possible time. Further, the counting
rates from each phototube as well as the analog sum of the 7 phototubes from
each telescope (royal sum) need to be monitored at regular intervals during the
run. In view of the complexity of the system, the entire array is divided into
four smaller sectors each of which is handled by an independent field signal
processing centre (FSPC) housed in a control room that collects, processes and
records information from nearby six telescopes that belong to that sector. The
distributed data acquisition system (DDAS) developed for the purpose consists
of stand-alone sector data acquisition system (SDAS) in each of the four FSPC's
and a master data acquisition system (MDAS). MDAS running in the master signal
processing centre (MSPC) records data from each of the 25 telescopes. The data
acquisition and monitoring PCs (SDAS and MDAS) are networked through LAN. The
entire real time software for DDAS is developed in C under $linux$ environment.
Most of the hardware in DDAS are designed and fabricated in-house. The design
features and the performance of the entire system along with some other
auxiliary systems to facilitate the entire observations will be presented.


title: Water in K and M giant stars unveiled by ISO

abstract:
  Based on the spectra obtained with Infrared Space Observatory, ISO, we
detected the 6.3 micron bands of water in the late K giant Aldebaran (alpha
Tau) and several early M giant stars between M0 and M3.5, which have been
deemed to be too warm for tri-atomic H2O molecule to reside in their
photospheres. The water column densities range 2E+17 - 2E+18 molecules/cm**2 in
our sample of K and M giant stars and the excitation temperatures are 1500 K or
higher. Thus, the water bands are not originating in cool stellar winds either.
The presence of water in the K and early M giant stars was quite unexpected
from the traditional picture of the atmosphere of the red giant star consisting
of the photosphere, hot chromosphere, and cool wind. We confirm that a rather
warm molecule forming region (referred to as MOLsphere) should exist as a new
component of the atmosphere of red giant stars and that this should be a
general phenomenon in late-type stars. ~


title:
Measurements of light transmission in deep sea with the AC9
  trasmissometer

abstract:
  The NEMO Collaboration aims to construct an underwater Cerenkov detector in
the Mediterranean Sea, able to act as a neutrino telescope. One of the main
tasks of this project, which implies difficult technological challenges, is the
selection of an adequate marine site. In this framework the knowledge of light
transmission properties in deep seawater is extremely important. The
collaboration has measured optical properties in several marine sites near the
Italian coasts, at depths >3000 m, using a set-up based on a AC9, a commercial
trasmissometer, manufactured by WETLabs. The results obtained for the two sites
reported in this paper Alicudi and Ustica, show that deep seawater optical
properties are comparable to those of the clearest waters.


title: Metallicities and Abundance Ratios from Quasar Broad Emission Lines

abstract:
  The broad emission lines (BELs) of quasars and active galactic nuclei (AGNs)
are important diagnostics of the relative abundances and overall metallicity in
the gas. Here we present new theoretical predictions for several UV BELs. We
focus specifically on the relative nitrogen abundance as a metallicity
indicator, based on the expected secondary enrichment of nitrogen at
metallicities Z > 0.2 Z_o. Among the lines we consider, N III] 1750/O III]
1664, N V 1240/(C IV 1549 + O VI 1034) and N V/He II 1640 are the most robust
diagnostics. We argue, in particular, that the average N V BEL is not dominated
by scattered Ly-alpha photons from a broad absorption line wind. We then
compare our calculated line ratios with observations from the literature. The
results support earlier claims that the gas-phase metallicities near quasars
are typically near or several times above the solar value. We conclude that
quasar activity is preceded by, or coeval with, an episode of rapid and
extensive star formation in the surrounding galactic (or proto-galactic)
nuclei. Chemical evolution models of these environments suggest that, to reach
Z > Z_o in well-mixed interstellar gas, the star formation must have begun >
10^8 yr before the observed quasar activity.


title:
Measurements of Cosmic-ray Low-energy Antiproton and Proton Spectra in a
  Transient Period of the Solar Field Reversal

abstract:
  The energy spectra of cosmic-ray low-energy antiprotons and protons have been
measured by BESS in 1999 and 2000, during a period covering the solar magnetic
field reversal. Based on these measurements, a sudden increase of the
antiproton to proton flux ratio following the solar magnetic field reversal was
observed, and it generally agrees with a drift model of the solar modulation.


title: The ionization fraction in alpha-models of protoplanetary disks

abstract:
  We calculate the ionization fraction of protostellar alpha disks, taking into
account vertical temperature structure, and the possible presence of trace
metal atoms. Both thermal and X-ray ionization are considered. Previous
investigations of layered disks used radial power-law models with isothermal
vertical structure. But alpha models are used to model accretion, and the
present work is a step towards a self-consistent treatment. The extent of the
magnetically uncoupled (``dead'') zone depends sensitively on alpha, on the
assumed accretion rate, and on the critical magnetic Reynolds number, below
which MHD turbulence cannot be self-sustained. Its extent is extremely
model-dependent. It is also shown that a tiny fraction of the cosmic abundance
of metal atoms can dramatically affect the ionization balance. Gravitational
instabilities are an unpromising source of transport, except in the early
stages of disk formation.


title: Optical observations of the dark Gamma-Ray Burst GRB 000210

abstract:
  We report on optical observations on GRB 000210 obtained with the 2.56-m
Nordic Optical Telescope and the 1.54-m Danish Telescope starting 12.4 hours
after the gamma-ray event. The content of the X-ray error box determined by the
Chandra satellite is discussed.


title:
Chemical abundance patterns -- fingerprints of nucleosynthesis in the
  first stars

abstract:
  The interstellar medium of low-metallicity systems undergoing star formation
will show chemical abundance inhomogeneities due to supernova events enriching
the medium on a local scale. If the star formation time-scale is shorter than
the time-scale of mixing of the interstellar matter, the inhomogeneities are
reflected in the surface abundances of low-mass stars and thereby detailed
information on the nucleosynthesis in the first generations of supernovae is
preserved. Characteristic patterns and substructures are therefore expected to
be found, apart from the large scatter behaviour, in the distributions of stars
when displayed in diagrams relating different element abundance ratios. These
patterns emerge from specific variations with progenitor stellar mass of the
supernova yields and it is demonstrated that the patterns are insensitive to
the initial mass function (IMF) even though the relative density of stars
within the patterns may vary. An analytical theory of the formation of patterns
is presented and it is shown that from a statistical point of view the
abundance ratios can trace the different nucleosynthesis sites even when mixing
of the interstellar medium occurs. Using these results, it should be possible
to empirically determine supernova yields from the information on relative
abundance ratios of a large, homogeneous sample of extremely metal-poor
Galactic halo stars.


title:
Blob Ejection from Advection-dominated Accretion Flow II: the
  Multiwavelength Properties of Light Curves

abstract:
  It has been argued that blobs ejected from advection-dominated accretion flow
through the accretion-ejection instability undergo expansion due to their high
internal energy density. The expanding blobs interact with their surroundings
and form strong shock, which accelerates a group of electrons to be
relativistic. Then flares are formed. This model has advances in two aspects:
shock acceleration and self-consistent injection. We derive an analytical
formula of the injection function of relativistic electrons based on the
Sedov's law. We calculate the time-dependent spectrum of relativistic electrons
in such an expanding blob. The light-travel effect, the evolution of the
electron spectrum due to energy loss, and the escape of relativistic electrons
from the radiating region are considered, as well as the expansion (at
sub-relativistic speed) of the coasting blob. A large number of light curves
spanning wide spaces of parameters have been given in this paper. Regarding the
symmetry, relative amplitude, duration of a flare, and the time lag between
peak fluxes, we find four basic kinds of light curves for the non-expanding
blob, and seven basic kinds of light curves for the expanding blob. We also
calculate the evolution of the photon spectrum from both non-expanding and
expanding blobs. Different shapes in the phase of decreasing luminosity are
then obtained for different parameter values. The photon index, $\alpha_{\rm
ph}$, keeps constant for non-expanding blobs when luminosity decreases, whereas
$\alpha_{\rm ph}$ continues to decrease after the luminosity reaches its
maximum for expanding blobs. It is expected that we can extract the information
of ejected blobs from the observed light curves based on the present model.


title:
First Results from the COLA Project- the Radio-FIR Correlation and
  Compact Radio Cores in Southern COLA Galaxies

abstract:
  We present the first results from the COLA (Compact Objects in Low-power AGN)
project which aims to determine the relationship between one facet of AGN
activity, the compact radio core, with star formation in the circumnuclear
region of the host galaxy. This will be accomplished by the comparison of the
multi-wavelength properties of a sample of AGN with compact radio cores to
those of a sample of AGN without compact cores and a matched sample of galaxies
without AGN.
  In this paper we discuss the selection criteria for our galaxy samples and
present the initial radio observations of the 107 Southern galaxies in our
sample. Low-resolution ATCA observations at 4.8, 2.5 and 1.4 GHz and high
resolution, single baseline snapshots at 2.3 GHz with the Australian LBA are
presented. We find that for the majority of the galaxies in our sample, the
radio luminosity is correlated with the FIR luminosity.
  Compact radio cores are detected in 9 galaxies. The majority (8/9) of these
galaxies exhibit a significant radio excess and 50% (7/14) of the galaxies
which lie above the radio-FIR correlation by more than 1 sigma have compact
radio cores. The emission from the cores is too weak to account for this radio
excess and there is no evidence that the radio luminosity of the compact cores
is correlated with the FIR galaxy luminosity.
  The galaxies with compact cores tend to be classified optically as AGN, with
two thirds (6/9) exhibiting Seyfert-like optical emission line ratios, and the
remaining galaxies classified either as composite objects (2/9) or starburst
(1/9). (Abridged)


title: Dust Absorption and the Cosmic UV Flux Density

abstract:
  We study the evolution of the galaxy UV luminosity density as a function of
redshift in the Hubble Deep Field North (HDF-N). We estimate the amount of
energy absorbed by dust and hidden from optical observations by analyzing the
HDF-N photometric data with the spectral energy distribution fitting method.
According to our results, at redshifts 1 < z < 4.5, the global energy observed
in the UV rest-frame at lambda=1500 A corresponds to only 7-11% of the stellar
energy output, the rest of it being absorbed by dust and re-emitted in the
far-IR. Our estimates of the comoving star formation rate density in the
universe from the extinction-corrected UV emission are consistent with the
recent results obtained with Submillimeter Common-User Bolometer Array
  (SCUBA) at faint sub-millimeter flux levels.


title:
Variability and spectral classification of LMC giants: results from
  DENIS and EROS

abstract:
  We present the first cross-identifications of sources in the near-infrared
DENIS survey and in the micro-lensing EROS survey in a field of about 0.5
square degrees around the optical center (OC) of the Large Magellanic Cloud. We
analyze the photometric history of these stars in the EROS data base and obtain
light-curves for about 800 variables. Most of the stars are long period
variables (Miras and Semi-Regulars), a few Cepheids are also present. We also
present new spectroscopic data on 126 asymptotic giant branch stars in the OC
field, 30 previously known and 96 newly discovered by the DENIS survey. The
visible spectra are used to assign a carbon- (C-) or oxygen-rich (O-rich)
nature to the observed stars on the basis of the presence of molecular bands of
TiO, VO, CN, C2. For the remaining of the stars we used the (J-Ks) color to
determine whether they are O-rich or C-rich. Plotting Log(period) versus Ks we
find three very distinct period-luminosity relations, mainly populated by
Semi-Regular of type a (SRa), b (SRb) and Mira variables. Carbon-rich stars
occupy mostly the upper part of these relations. We find that 65% of the
asymptotic giant branch population are long period variables (LPVs).


title:
Cascades in the Earth's magnetosphere initiated by photons with the
  parameters of the highest energy AGASA events

abstract:
  We investigate the cascading effects of extremely high energy (EHE) photons
in the Earth's magnetosphere assuming that these photons arrive with the
parameters of the highest energy AGASA events (energies, arrival directions).
For the location of the AGASA Observatory, we determine the directions in the
sky from which photons can cascade with a high (low) probability. In the case
of the primary photons with the parameters of the events with the energies $>
10^{20}$ eV, we compute the average cascade spectra of secondary photons
entering the Earth's atmosphere, and estimate their fluctuations around these
average values by selecting the events with the largest and smallest number of
secondary cascade photons. It is shown that most photons with the parameters of
the highest energy AGASA events should initiate cascades in the Earth's
magnetosphere with a high probability even though they tend to arrive from
directions in the sky for which the perpendicular component of the magnetic
field is weaker. On the other hand, if these events are caused by the photons
with lower energies, then the fluctuations in their shower development in the
magnetosphere and the atmosphere should be higher than in the case of photons
with the energies estimated by the AGASA experiment.


title: Modified Newtonian Dynamics of Large Scale Structure

abstract:
  We examine the implications of Modified Newtonian Dynamics (MOND) on the
large scale structure in a Friedmann-Robertson-Walker universe. We employ a
``Jeans swindle'' to write a MOND-type relationship between the fluctuations in
the density and the gravitational force, $\vg$. In linear Newtonian theory,
$|\vg|$ decreases with time and eventually becomes $<g_0$, the threshold below
which MOND is dominant. If the Newtonian initial density field has a power-law
power-spectrum of index $n<-1$, then MOND domination proceeds from small to
large scale. At early times MOND tends to drive the density power-spectrum
towards $k^{-1}$, independent of its shape in the Newtonian regime. We use
N-body simulations to solve the MOND equations of motion starting from initial
conditions with a CDM power-spectrum. MOND with the standard value $g_0=10^{-8}
cm s^{-2}$, yields a high clustering amplitude that can match the observed
galaxy distribution only with strong (anti-) biasing. A value of $g_0 \approx
10^{-9}cm s^{-2}$, however, gives results similar to Newtonian dynamics and can
be consistent with the observed large scale structure.


title: Scaling and correlation analysis of galactic images

abstract:
  Different scaling and autocorrelation characteristics and their application
to astronomical images are discussed: the structure function, the
autocorrelation function, Fourier spectra and wavelet spectra. We recommend as
the optimal mathematical tool the wavelet spectrum with a suitable choice of
the analysing wavelet. We introduce the wavelet cross-correlation function
which enables to study the correlation between images as a function of scale.
The wavelet cross-correlation coefficient strongly depends on the scale. The
classical cross-correlation coefficient can be misleading if a bright, extended
central region or an extended disk exists in the galactic images. An analysis
of the scaling and cross-correlation characteristics of 9 optical and radio
maps of the nearby spiral galaxy NGC 6946 is presented. The wavelet spectra
allow to separate structures on different scales like spiral arms and diffuse
extended emission. Only the images of thermal radio emission and Halpha
emission give indications of 3-dimensional Kolmogorov-type turbulence on the
smallest resolved scales (160-800 pc). The cross-correlations between the
images of NGC 6946 show strong similarities between the images of total radio
emission, red light and mid-infrared dust emission on all scales. The best
correlation is found between total radio emission and dust emission. Thermal
radio continuum and Halpha emission are best correlated on a scale of about 1'
\simeq 1.6 kpc, the typical width of a spiral arm. On a similar scale, the
images of polarised radio and Halpha emission are anticorrelated, which remains
undetected with classical ross-correlation analysis.


title: Confirming the Metal-Rich Nature of Stars with Giant Planets

abstract:
  With the goal of confirming the metallicity ``excess'' observed in stars with
planetary mass companions, we have conducted a high-precision spectroscopic
study of a ``comparison'' sample of dwarfs included in the CORALIE extra-solar
planet survey (Santos, Israelian, & Mayor 2001). The targets were chosen
following two basic criteria: they make part of a limited volume and they do
not present the signature of a planetary host companion. The spectroscopic
analysis, done using the very same technique as previous works on the
metallicity of stars with planets, permitted a direct and non-biased comparison
of the samples. The results have revealed that metallicity plays an impressive
role on the giant planet formation. The chemical composition of the molecular
cloud is probably the key parameter to form giant planets. Some evidences
exist, however, showing the possibility of accretion of matter in the stellar
outer convective zone. These conclusions impose serious constraints on the
planetary systems formation and evolution models.


title: Slim Disk: Viscosity Prescriptions and Observational Implications

abstract:
  We examine the effects of the different viscosity prescriptions and the
magnitude of the viscosity parameter, $\alpha$, on the structure of the slim
disk, and discuss the observational implications on accretion-flow into a
stellar-mass black hole. For the range of $\alpha = 10^{-2} \sim 10^{0}$ we
calculate the disk spectra and from spectral fitting we derive $\Tin$, maximum
temperature of the disk, $\Rin$, the size of the region emitting blackbody
radiation with $\Tin$, and $p\equiv -{\rm dln} T_{\rm eff}/{\rm dln}~r$, the
slope of the effective temperature distribution. It was founded that the
estimated $\Tin$ slightly increases as $\alpha$ increases. This is because the
larger the magnitude of viscosity is, the larger becomes the accretion velocity
and, hence, the more enhanced becomes advective energy transport, which means
less efficient radiative cooling and thus higher temperatures. Furthermore we
check different viscosity prescriptions with the form of the viscous stress
tensor of $t_{r \varphi} = -\alpha \beta^{\mu}p_{\rm total}$, where $\beta$ is
the ratio of gas pressure to total pressure, and $\mu$ is a parameter ($0 \le
\mu \le 1$). For $\mu=0$ we have previously found that as luminosity approaches
the Eddington, $L_{\rm E$, $\Rin$ decreases below 3$\rg$ (with $r_{\rm g}$
being Schwarzschild radius) and the effective temperature becomes flatter,
$T_{\rm eff} \propto r^{-1/2}$. Such a slim-disk nature does not appear when
$\mu$ is large, $\mu \sim 0.5$, even at $L_{\rm E}$. Hence, the temperature of
the innermost region of the disk sensitively depends on the $\mu$ value. We can
rule out the case with large $\mu~(\sim 0.5)$, since it will not be able to
produce a drop in $\Rin$ with an increase in luminosity as was observed in an
ultraluminous X-ray source, IC~342, source 1.


title:
GRB 000301C: a possible short/intermediate duration burst connected to a
  DLA system

abstract:
  We discuss two main aspects of the GRB 000301C afterglow (Fynbo et al. 2000,
Jensen et al. 2000); its short duration and its possible connection with a
Damped Ly-alpha Absorber (DLA). GRB 000301C falls in the short class of bursts,
though it is consistent with belonging to the proposed intermediate class or
the extreme short end of the distribution of long-duration GRBs. Based on two
VLT spectra we estimate the HI column density to be Log(N(HI))=21.2+/-0.5. This
is the first direct indication of a connection between GRB host galaxies and
Damped Ly-alpha Absorbers.


title: Molecular ions in L1544. I. Kinematics

abstract:
  We have mapped the dense dark core L1544 in H13CO+(1-0), DCO+(2-1),
DCO+(3-2), N2H+(1-0), NTH+(3-2), N2D+(2-1), N2D+(3-2), C18O(1-0), and C17O(1-0)
using the IRAM 30-m telescope. We have obtained supplementary observations of
HC18O+(1-0), HC17O+(1-0), and D13CO+(2-1). Many of the observed maps show a
general correlation with the distribution of dust continuum emission in
contrast to C18O(1-0) and C17O(1-0) which give clear evidence for depletion of
CO at positions close to the continuum peak. In particular N2D+(2-1) and (3-2)
and to a lesser extent N2H+(1-0) appear to be excellent tracers of the dust
continuum. We find that the tracers of high density gas (in particular N2D+)
show a velocity gradient along the minor axis of the L1544 core and that there
is evidence for larger linewidths close to the dust emission peak. We interpret
this using the model of the L1544 proposed by Ciolek & Basu (2000) and by
comparing the observed velocities with those expected on the basis of their
model. The results show reasonable agreement between observations and model in
that the velocity gradient along the minor axis and the line broadening toward
the center of L1544 are predicted by the model. This is evidence in favour of
the idea that amipolar diffusion across field lines is one of the basic
processes leading to gravitational collapse. However, line widths are
significantly narrower than observed and are better reproduced by the Myers &
Zweibel (2001) model which considers the quasistatic vertical contraction of a
layer due to dissipation of its Alfvenic turbulence, indicating the importance
of this process for cores in the verge of forming a star.