title:
Rayleigh - Taylor Gravity Waves and Quasiperiodic Oscillation Phenomenon
  in X-ray Binaries

abstract:
  Accretion onto compact objects in X-ray binaries [black hole, neutron star
(NS), white dwarf] is characterized by non-uniform flow density profiles. Such
an effect of heterogeneity in presence of gravitational forces and pressure
gradients exhibits Raylegh-Taylor gravity waves (RTGW). They should be seen as
quasioperiodic wave oscillations (QPO). In this paper I show that the main QPO
frequency, which is very close to the Keplerian frequency, is split into
separate frequencies (hybrid and low branch) under the influence of the
gravitational forces in the rotational frame of reference. The observed low and
high QPO frequencies are an intrinsic signature of the RTGW. I elaborate the
conditions for the density profile when the RTGW oscillations are stable. A
comparison of the inferred QPO frequencies with QPO observations is presented.
I find that hectohertz frequencies detected from NS binaries can be identified
as the RTGW low branch frequencies. I also predict that an observer can see the
double NS spin frequency during the NS long (super) burst events when the
pressure gradients and buoyant forces are suppressed. The Coriolis force is the
only force which acts in the rotational frame of reference and its presence
causes perfect coherent pulsations with a frequency twice of the NS spin.


title:
The Chemistry of Dark Clouds: New Astrochemical Tools for Star Formation
  Studies

abstract:
  The past decade has led to significant improvements in our understanding of
the physical structure of the molecular cores of cold dark clouds.
Observational efforts, in combination with improved knowledge of cloud
structure, now provide clear evidence that the chemistry of dark clouds is
dominated by the depletion of gaseous species onto grain surfaces. We outline
the basis of these observational efforts and show how the abundance
determinations have moved beyond single point analyses to the derivation of
abundance profiles. We discuss the basic physics of the interaction between
molecules and grain surfaces and show that when physics is coupled into a
chemical model there is excellent agreement, for a limited set of species,
between theory and observations. We discuss our improved understanding of cloud
chemistry can be used as a new tool for studies of the formation of stars and
planetary systems.


title:
Results from a VLT-ISAAC survey of ices and gas around young stellar
  objects

abstract:
  General results from a 3-5 micron spectroscopic survey of nearby low-mass
young stellar objects are presented. L and M-band spectra have been obtained of
\~50 low mass embedded young stars using the ISAAC spectrometer mounted on
UT1-Antu at Paranal Observatory. For the first time, a consistent census of the
CO, H2O ices and the minor ice species CH3OH and OCN- and warm CO gas present
around young stars is obtained, using large number statistics and resolving
powers of up to R=10000. The molecular structure of circumstellar CO ices, the
depletion of gaseous CO onto grains in protoplanetary disks, the presence of
hot gas in the inner parts of circumstellar disks and in outflows and infalls
are studied. Furthermore, the importance of scattering effects for the
interpretation of the spectra have been addressed.


title:
Fast Photometry of Quiescent Soft X-ray Transients with the Gemini-South
  Acquisition Camera

abstract:
  We present a compilation of high time-resolution photometric observations of
quiescent soft X-ray transients obtained with the acquisition camera of
Gemini-South. A0620-00 was observed with a short cycle time and high precision.
Superimposed on the ellipsoidal modulation we find several prominent flares
together with weaker continual variability. The flares seen sample shorter
timescale than those reported in previous observations, with rise times as low
as 30s or less; most flares show unresolved peaks. The power density spectrum
(PDS) of A0620-00 appears to exhibit band-limited noise closely resembling the
X-ray PDS of black hole candidates in their low states, but with the
low-frequency break at a lower frequency. X-ray Nova Mus 1991 shows much larger
amplitude flares than A0620-00 and if a break is present it is at a lower
frequency. X-ray Nova Vel 1993 shows very little flaring and is, like A0620-00,
dominated by the ellipsoidal modulation. We discuss the possible origins for
the flares. They are clearly associated with the accretion flow rather than an
active companion, but whether they originate in the outer disc, or are driven
by events in the inner region is not yet resolved. The similarities of the PDS
to those of low/hard state sources would support the latter interpretation, and
the low break frequency is as would be expected if this frequency approximately
scales with the size of an inner evaporated region. We also report the
discovery of a new variable star only 14arcsec from XN Mus 1991. This appears
to be a W UMa star, with an orbital period of about 6hrs.


title:
High Temperature Matter and Neutrino Spectra from Microscopic Black
  Holes

abstract:
  The spectrum of neutrinos produced by the outflow of high temperature matter
surrounding microscopic black holes is calculated for neutrino energies between
one GeV and the Planck energy. The results may be applicable for the last few
hours and minutes of a microscopic black hole's lifetime.


title: R-modes of neutron stars with the superfluid core

abstract:
  We investigate the modal properties of the $r$-modes of rotating neutron
stars with the core filled with neutron and proton superfluids, taking account
of entrainment effects between the superfluids. The stability of the $r$-modes
against gravitational radiation reaction is also examined considering viscous
dissipation due to shear and a damping mechanism called mutual friction between
the superfluids in the core. We find the $r$-modes in the superfluid core are
split into ordinary $r$-modes and superfluid $r$-modes, which we call,
respectively, $r^o$- and $r^s$-modes. The two superfluids in the core flow
together for the $r^o$-modes, while they counter-move for the $r^s$-modes. For
the $r^o$-modes, the coefficient $\kappa_0\equiv\lim_{\Omega\to
0}\omega/\Omega$ is equal to $2m/[l^\prime(l^\prime+1)]$, almost independent of
the parameter $\eta$ that parameterizes the entrainment effects between the
superfluids, where $\Omega$ is the angular frequency of rotation, $\omega$ the
oscillation frequency observed in the corotating frame of the star, and
$l^\prime$ and $m$ are the indices of the spherical harmonic function
representing the angular dependence of the $r$-modes. For the $r^s$-modes, on
the other hand, $\kappa_0$ is equal to $2m/[l^\prime(l^\prime+1)]$ at $\eta=0$
(no entrainment), and it almost linearly increases as $\eta$ is increased from
$\eta=0$. The mutual friction in the superfluid core is found ineffective to
stabilize the $r$-mode instability caused by the $r^o$-mode except in a few
narrow regions of $\eta$. The $r$-mode instability caused by the $r^s$-modes,
on the other hand, is extremely weak and easily damped by dissipative processes
in the star.


title: Molecular Abundances in B68

abstract:
  Abundances for C18O, CS, NH3, H2CO, C3H2, and N2H+ and upper limits for the
abundances of 13CO and HCO+ are derived for gas within the Bok globule B68
using our own BIMA array data, single-dish data from the literature, and Monte
Carlo radiative transfer models. B68 has had its density structure well
determined, removing a major uncertainty from abundance determinations. All
abundances for B68 are lower than those derived for translucent and cold dense
clouds, but perhaps only significantly for N2H+, NH3, and C3H2. CS depletion
toward the extinction peak of B68 is hinted at by the large offset between the
extinction peak and the position of maximum CS line brightness. C18O and N2H+
abundances derived here are consistent with recently determined values at
positions observed in common.


title: The Enigmatic HH 255

abstract:
  To gain insight into the nature of the peculiar Herbig-Haro object HH 255
(also called Burnham's nebula), we use previously published observations to
derive information about the emission line fluxes as a function of position
within HH 255 and compare them with the well-studied, and relatively
well-behaved bow shock HH 1. There are some qualitative similarities in the
H$\alpha$ and [O III] 5007 lines in both objects. However, in contrast to the
expectation of the standard bow shock model, the fluxes of the [O I] 6300, [S
II] 6731, and [N II] 6583 lines are essentially constant along the axis of the
flow, while the electron density decreases, over a large distance within HH
255.
  We also explore the possibility that HH 255 represents the emission behind a
standing or quasi-stationary shock. The shock faces upwind, and we suggest,
using theoretical arguments, that it may be associated with the collimation of
the southern outflow from T Tauri. Using a simplified magnetohydrodynamic
simulation to illustrate the basic concept, we demonstrate that the existence
of such a shock at the north edge of HH 255 could indeed explain its unusual
kinematic and ionization properties. Whether or not such a shock can explain
the detailed emission line stratification remains an open question.


title: The Breakout of Protostellar Winds in the Infalling Environment

abstract:
  The time of protostellar wind breakout may be determined by the evolution of
the infalling flow, rather than any sudden change in the central engine. I
examine the transition from pure infall to outflow, in the context of the
inside-out collapse of a rotating molecular cloud core. I have followed
numerically the motion of the shocked shell created by the impact of a stellar
wind and infalling gas. These fully time-dependent calculations include cases
both where the shell falls back to the stellar surface, and where it breaks out
as a true outflow. Assuming a wind launched from the protostellar surface, the
breakout time is determined in terms of the parameters describing the wind
(Mdot_w, V_w) and collapsing cloud core (a_0, Omega). The trapped wind phase
consists of a wind sufficiently strong to push material back from the stellar
surface, but too weak to carry the heavy, shocked infall out of the star's
gravitational potential. To produce a large-scale outflow, the shocked material
must be able to climb out of the star's gravitational potential well, carrying
with it the dense, swept-up infall.


title:
On the Background Rate in the LXeGRIT Instrument during the 2000 Balloon
  Flight

abstract:
  LXeGRIT is the first prototype of a novel Compton telescope for MeV gamma-ray
astrophysics based on a Liquid Xenon Time Projection Chamber (LXeTPC),
sensitive in the energy band of 0.15-10 MeV. In this homogeneous, 3D position
sensitive detector, gamma rays with at least two interactions in the sensitive
volume of 2800 cm$^{3}$, are imaged as in a standard Compton telescope.
Gamma-rays with a single interaction cannot be imaged and constitute a
background which can be easily identified and rejected. Charged particles and
localized beta-particles background is also easily suppressed based on the TPC
localization capability with millimeter resolution. A measurement of the total
gamma-ray background rate in near space conditions and the background rejection
power of the LXeTPC was a primary goal of the LXeGRIT balloon flight program.
We present here a preliminary analysis addressing this question, based on
balloon flight data acquired during the Oct 4-5, 2000 LXeGRIT balloon flight
from Ft. Sumner, NM. In this long duration (27 hr) balloon experiment, the
LXeGRIT TPC was not surrounded by any gamma-ray or charged particle shield.
Single site events and charged particles were mostly rejected on-line at the
first and second trigger level. The remaining count rate of single-site \g-ray
events, at an average atmospheric depth of 3.2 g cm$^{-2}$, is consistent with
that expected from atmospheric and diffuse gamma-ray background, taking into
account the instrument mass model and response.


title:
Azimuthal and Kinematic Segregation of Neutral and Molecular Gas in Arp
  118: The Yin-Yang Galaxy NGC 1144

abstract:
  We present new high-resolution HI observations of the disk of the collisional
infrared luminous (L$_{\rm IR}=2.2\times10^{11}$ L$_{\sun}$) galaxy NGC 1144,
which reveal an apparent large-scale azimuthal and kinematic segregation of
neutral hydrogen relative to the molecular gas distribution. Even among
violently collisional galaxies, the CO/HI asymmetry in NGC 1144 is unusual,
both in the inner regions, and in the outer disk. We suggest that we are
observing Arp 118 at a special moment, shortly after a high-speed collision
between NGC 1144 and its elliptical companion NGC 1143. HI emission with an
average molecular fraction f$_{mol}$ $<$ 0.5 is observed on one side (NW) of
the rotating disk of NGC 1144, while the other side (SE) is dominated by dense
molecular complexes in which f$_{mol}$ is almost unity. The interface region
between the warm-- and cool--cloud dominated regions, lies on a deep
spiral-like dust-lane which we identify as a shock-wave responsible for the
relative shift in the dominance of HI and H$_2$ gas. A strong shock being fed
by diffuse HI clouds with unusually large ($>$ 400 km s$^{-1}$) rotational
velocities can explain: 1) the CO/HI asymmetries, 2) a large velocity jump (185
km s$^{-1}$) across the arm as measured by HI absorption against a radio bright
continuum source which straddles the arm, and 3) the asymmetric distribution of
star formation and off-nuclear molecular gas resulting from likely streaming
motions associated with the strong-shock. The new results provide for the first
time a coherent picture of Arp 118's many peculiarities, and underlines the
potentially complex changes in the gas-phase that can accompany large
gravitational perturbations of gas-rich galaxies.


title:
Simultaneous Modelling of the Stellar Halo and Globular Cluster System
  of NGC 5128

abstract:
  An important test for models of galaxy formation lies in the metallicity
distribution functions (MDFs) of spheroid stars and their globular clusters
(GCs).We have compared the MDFs obtained from spectroscopy of the GCs and the
star-by-star photometry of red giants in the nearby elliptical NGC 5128, with
the predictions of a semi-analytic galaxy formation model. We have selected
model ellipticals comparable in luminosity and environment to NGC 5128, and
derived their MDFs. A direct comparison between models and data shows that the
MDFs are qualitatively similar, both have stellar components which are
predominantly metal-rich (0.8Z), with a small fraction of metal-poor stars
extending down to 0.002Z. The model MDFs show only small variations, whether
they are brightest cluster galaxies or low luminosity group ellipticals. Our
comparison also reveals that these model MDFs harbour a greater fraction of
stars above solar metallicity than the observations, producing generally more
metal-rich (by 0.1 dex) MDFs. One possibility is that the outer-bulge
observations are missing some of the highest metallicity stars. We find good
agreement between the model and observed GC MDFs, provided that the metal-poor
GC formation is halted early in the model. Under this proviso, both the models
and data are bimodal with peaks at 0.1Z and Z, and cover similar metallicity
ranges. This broad agreement for the stars and GCs suggests that the bulk of
the stellar population in NGC 5128 may have been built up in a hierarchical
fashion, involving both quiescent and merger-induced star formation. The
existence of age structure amongst the metal-rich GCs needs to be tested
against high-quality data for this galaxy.


title: Learning about Jets from Observations of Blazars

abstract:
  Jets, paving their way outward through the inner regions of active nuclei,
Compton-interact with the UV radiation from an accretion disc and broad
emission line region. We calculate the predicted properties of the resulting
spectral signatures of this bulk-Compton process, noting that they are
independent on the fractional proton content or kinetic power of the jet, and
use the presence or absence of such signatures to put constraints on the
structure of jets near their bases.


title:
Thermally Driven Outflows from Pair-Plasma Pressure Mediated Shock
  Surfaces around Schwarzschild Black Holes

abstract:
  Introducing a spherical, steady, self-supported pair-plasma pressure mediated
shock surface around a Schwarzschild black hole as the effective physical
atmosphere which may be responsible for the generation of astrophysical mass
outflows from relativistic quasi-spherical accretion, we calculate the mass
outflow rate $R_{\dot m}$ by simultaneously solving the set of equations
governing transonic polytropic accretion and isothermal winds. $R_{\dot m}$ is
computed in terms of {\it only three} inflow parameters, which, as we believe,
has been done for the first time in our work. We then study the dependence of
$R_{\dot m}$ on various inflow as well as shock parameters and establish the
fact that the outflow rate is essentially controlled by the post-shock proton
temperature.


title: Signatures of SN Ia in the galactic thick disk

abstract:
  We present the first results of a larger study into the stellar abundances
and chemical trends in long-lived dwarf stars in the solar neighbourhood that
belong to (based on their kinematics) the thin and thick galactic disk,
respectively. We confirm that the trends of alpha-elements in the thin and
thick disk are distinct (this has previously been shown for Mg by Fuhrmann
1998, but e.g. Chen et al. 2000 claimed the trends to follow smoothly upon each
other). We find that the thick disk show the typical signature of contribution
from SN Ia (i.e. the ``knee'') to the enrichment of the interstellar gas out of
which the later generations of thick disk stars formed. The trend starts out as
[Mg/Fe] ~0.35 at [Fe/H] ~ -0.7 and continue on this level with increasing
[Fe/H] until -0.4 dex where a decline in [Mg/Fe] starts and steadily continues
down to 0 dex at solar metallicity. The same is true for the other
alpha-elements (e.g. Si). Using ages from the literature we find that the thick
disk in the mean is older than the thin disk. Combining our results with other
observational facts we suggest that the most likely formation scenario for the
thick disk is, still, a violent merger event. We also suggest that there might
be tentativeevidence for diffusion of orbits in todays thin disk (based on
kinematics in combination with elemental abundances).


title:
Environmental Enhancement of Loose Groups around Rich Clusters of
  Galaxies

abstract:
  We have studied the properties of Las Campanas Loose Groups in the
neighbourhood of rich (Abell, APM and X-ray) clusters of galaxies. These loose
groups show strong evidence of segregation measured in terms of the group
richness and the group velocity dispersion: loose groups in the neighbourhood
of a rich cluster are typically 2.5 times more massive and 1.6 times more
luminous than groups on average, and these loose groups havevelocity
dispersions 1.3 times larger than groups on average. This is evidence that the
large-scale gravitational field causing the formation of rich clusters enhances
the evolution of neighbouring poor systems, a phenomenon recently established
in numerical simulations of group and cluster formation.


title: On the Connection between Mean Field Dynamo Theory and Flux Tubes

abstract:
  Mean field dynamo theory deals with various mean quantities and does not
directly throw any light on the question of existence of flux tubes. We can,
however, draw important conclusions about flux tubes in the interior of the Sun
by combining additional arguments with the insights gained from solar dynamo
solutions. The polar magnetic field of the Sun is of order 10 G, whereas the
toroidal magnetic field at the bottom of the convection zone has been estimated
to be 100,000 G. Simple order-of-magnitude estimates show that the shear in the
tachocline is not sufficient to stretch a 10 G mean radial field into a 100,000
G mean toroidal field. We argue that the polar field of the Sun must get
concentrated into intermittent flux tubes before it is advected to the
tachocline. We estimate the strengths and filling factors of these flux tubes.
Stretching by shear in the tachocline is then expected to produce a highly
intermittent magnetic configuration at the bottom of the convection zone. The
meridional flow at the bottom of the convection zone should be able to carry
this intermittent magnetic field equatorward, as suggested recently by Nandy
and Choudhuri (2002). When a flux tube from the bottom of the convection zone
rises to a region of pre-existing poloidal field at the surface, we point out
that it picks up a twist in accordance with the observations of current
helicities at the solar surface.


title: Multiple merging events in Abell 521

abstract:
  We present a detailed spatial and dynamical analysis of the central
$\sim$~2.2~\h~Mpc region of the galaxy cluster Abell~521 (z=0.247), based on
238 spectra obtained at the 3.6~m Telescope of ESO and at the CFHT. From the
analysis of the 125 galaxies confirmed members of the cluster, we derive a mean
velocity of $74019 ^{+112}_{-125}$ km/s and detect a complex velocity
distribution with high velocity dispersion, $1325 ^{+145}_{-100}$ km/s), but
clear departure from a single gaussian component. The general structure of the
cluster follows a NW/SE direction, crossed by a perpendicular high density
``ridge'' of galaxies in the core region. The northern region of the cluster is
characterized by a lower velocity dispersion as compared to the whole cluster
value; it hosts the BCG and a dynamically bound complex of galaxies, and it is
associated to a group detected in X-ray (Arnaud et al 2000). This region could
be in pre-merger stage onto the main cluster nearly in the plane of the sky.
These results, taken together with the fact that most of the clumps detected on
the isodensity maps, as well as the early type galaxies and the brightest ones
are aligned, suggest that this NW/SE direction is the preferred one for the
formation of this cluster. The central high dense region shows a lower velocity
location ($73625 ^{+344}_{-350}$ km/s) and significantly higher scale ($1780
^{+234}_{-142}$ km/s) as compared to the whole cluster values. This is due to
the presence of a low-velocity group of galaxies with a high fraction of
emission line objects. This can be explained in a scenario in which a merging
of subclusters has recently occurred along the direction of the ``ridge'' with
a significant component along the line of sight.


title: Regions of Star Formation: Chemical Issues.(Discussion Session)

abstract:
  Three are the main questions that were posed to the audience during this
discussion session: a) Can galaxy abundances be believed?, b) What progress can
we expect soon and from where? and c) Can we agree, as a community, on topics
in which effort should be concentrated in the next five years? In what follows,
the different contributions by people in the audience are reflected as they
were said trying to convey the lively spirit that enlightened the discussion.


title:
Detection of HCN Direct l-Type Transitions Probing Hot Molecular Gas in
  the Proto-Planetary Nebula CRL 618

abstract:
  We report the detection of direct l-type transitions towards the
proto-planetary nebula CRL 618 during a study of vibrationally excited carbon
chains. The J=8,10,11,12,13,14 DJ=0 transitions of HCN in its first excited
bending mode v2=1 were detected in absorption against the continuum of the
central HII region making use of the Effelsberg 100m telescope and the Very
Large Array. Additionally, the J=9 direct l-type transition was detected in
emission presumably indicating a weak maser. All lines are blueshifted with
respect to the systemic velocity of CRL 618 indicating that the lines originate
from a hot, expanding circumstellar envelope. The HCN column density along the
line of sight in front of the continuum is 2E18 cm^-2.


title:
A new method for nuclear-reaction network analysis, element production
  in S-Cl region during the He and C burning in 25 Ms stars

abstract:
  This paper presents the results of calculation of element overproduction in
the S-Cl region during helium and carbon burning in massive stars (25 Ms).
Calculations for a given set of differential equations were performed using
integrated mathematical systems. The authors think that this method may be
successfully adopted for other physical problems in which solving
nuclear-reaction network play an important role, in particular for the problem
of transmutation of heavy elements and chemical kinetics.


title: Fireballs and cannonballs confront the afterglow of GRB 991208

abstract:
  Galama et al. have recently reported their follow-up measurements of the
radio afterglow (AG) of the Gamma Ray Burst (GRB) 991208, up to 293 days after
burst, and their reanalysis of the broad-band AG, in the framework of standard
fireball models. They advocate a serious revision of their prior analysis and
conclusions, based on optical data and on their earlier observations during the
first two weeks of the AG. We comment on their work and fill a lacuna: these
authors have overlooked the possibility of comparing their new data to the
available predictions of the cannonball (CB) model, based --like their
incorrect predictions-- on the first round of data. The new data are in good
agreement with these CB-model predictions. This is in spite of the fact that,
in comparison to the fireball models, the CB model is much simpler, much more
predictive, has many fewer parameters, practically no free choices... and it
describes well --on a universal basis-- all the measured AGs of GRBs of known
redshift.


title: Strangelets as Cosmic Rays beyond the Greisen-Zatsepin-Kuzmin Cutoff

abstract:
  Strangelets (stable lumps of quark matter) can have masses and charges much
higher than those of nuclei, but have very low charge-to-mass ratios. This is
confirmed in a relativistic Thomas-Fermi model. The high charge allows
astrophysical strangelet acceleration to energies orders of magnitude higher
than for protons. In addition, strangelets are much less susceptible to the
interactions with the cosmic microwave background that suppress the flux of
cosmic ray protons and nuclei above energies of $10^{19}$--$10^{20}$ eV (the
GZK-cutoff). This makes strangelets an interesting possibility for explaining
ultra-high energy cosmic rays.


title: The Tully-Fisher relation of cluster spirals at z = 0.83

abstract:
  We present the rest-frame B-band Tully-Fisher relation for a sample of 8
cluster spiral galaxies at z = 0.83 and 19 field spirals at z = 0.15-0.90 based
on VLT spectroscopy and HST photometry. No strong difference is detected
between the cluster and the field galaxies, but we find some evidence that the
cluster spirals are ~0.5-1 mag brighter than the field ones at a fixed rotation
velocity. Although only a ~1.5-2 sigma result, if confirmed with larger samples
this effect could be due to the cluster spirals experiencing a period of
enhanced star formation while falling into the cluster.


title: The clustering of halo mergers

abstract:
  We analyse the spatial distribution of halo merger sites using four numerical
simulations with high time resolution of structure growth in a Lambda-CDM
cosmology. We find no evidence for any large-scale relative bias between
mergers and randomly selected haloes of the same mass at high redshift. Given a
sample of galaxies that form a Poisson sampling of halo mergers, then the
amplitude of the measured clustering ought to lead to a robust estimate of the
median host halo mass. In the hierarchical picture of structure growth, mergers
between galaxies at high redshifts are thought to create dust enshrouded
starbursts leading to increased emission in the sub-mm wavebands. Hence, a
measurement of the clustering strength of SCUBA galaxies, for example, can
determine whether or not they are giant elliptical galaxies in the process of
formation.


title: The cosmological constant and general isocurvature initial conditions

abstract:
  We investigate in detail the question whether a non-vanishing cosmological
constant is required by present-day cosmic microwave background and large scale
structure data when general isocurvature initial conditions are allowed for. We
also discuss differences between the usual Bayesian and the frequentist
approaches in data analysis. We show that the COBE-normalized matter power
spectrum is dominated by the adiabatic mode and therefore breaks the degeneracy
between initial conditions which is present in the cosmic microwave background
anisotropies. We find that in a flat universe the Bayesian analysis requires
\Omega_\Lambda \neq 0 to more than 3 \sigma, while in the frequentist approach
\Omega_\Lambda = 0 is still within 3 \sigma for a value of h < 0.48. Both
conclusions hold regardless of initial conditions.


title:
MHD simulations of the long-term evolution of a dipolar magnetosphere
  surrounded by an accretion disk

abstract:
  The evolution of an initially stellar dipole type magnetosphere interacting
with an accretion disk is investigated using numerical ideal MHD simulations.
The simulations follow several 1000 Keplerian periods of the inner disk. The
initial dipole type magnetic field develops into a spherically radial outflow
pattern with two main components both evolving into a quasi-stationary final
state. A neutral field line divides both components, along which small
plasmoids are ejected in irregular time intervals. The half opening angle of
the stellar wind cone varies from 30 to 55 degrees depending on the ratio of
the mass flow rates of disk wind and stellar wind. The maximum speed of the
outflow is about the Keplerian speed at the inner disk radius. An axial jet
forms during the first decades of rotation. However, this feature does not
survive on the very long time scale and a pressure driven low velocity flow
along the axis evolves.


title:
Large-scale curvature and entropy perturbations for multiple interacting
  fluids

abstract:
  We present a gauge-invariant formalism to study the evolution of curvature
perturbations in a Friedmann-Robertson-Walker universe filled by multiple
interacting fluids. We resolve arbitrary perturbations into adiabatic and
entropy components and derive their coupled evolution equations. We demonstrate
that perturbations obeying a generalised adiabatic condition remain adiabatic
in the large-scale limit, even when one includes energy transfer between
fluids. As a specific application we study the recently proposed curvaton
model, in which the curvaton decays into radiation. We use the coupled
evolution equations to show how an initial isocurvature perturbation in the
curvaton gives rise to an adiabatic curvature perturbation after the curvaton
decays.


title:
High resolution soft X-ray spectroscopy of the elliptical galaxy NGC
  5044. Results from the reflection grating spectrometer on-board XMM-Newton

abstract:
  The results from an X-ray spectroscopic study of the giant elliptical galaxy
NGC5044 in the center of a galaxy group are presented. The line dominated soft
X-ray spectra (mainly Fe-L and O VIII Ly_a) from the diffuse gas are resolved
for the first time in this system with the Reflection Grating Spectrometers
on-board XMM-Newton and provide a strong constraint on the temperature
structure. The spectra integrated over 2' (\sim 20kpc) in full-width can be
described by a two temperature plasma model of 0.7keV and 1.1keV. Most of the
latter component is consistent with originating from off-center regions.
Compared to the isobaric cooling flow prediction, the observation shows a clear
cut-off below a temperature of 0.6 +-0.1keV. Furthermore, the Fe and O
abundances within the central 10--20kpc in radius are accurately measured to be
0.55+-0.05 and 0.25+-0.1 times the solar ratios, respectively. The observed
cut-off temperature of this galaxy and other central galaxies in galaxy groups
and clusters are compared with the scale of the galaxy and properties of the
surrounding intra-cluster medium. Based on this comparison, the origin of the
lack of predicted cool emission is discussed.


title:
Sidereal time analysis as a toll for the study of the space distribution
  of sources of gravitational waves

abstract:
  Gravitational wave (GW) detectors operating on a long time range can be used
for the study of space distribution of sources of GW bursts or to put strong
upper limits on the GW signal of a wide class of source candidates. For this
purpose we propose here a sidereal time analysis to analyze the output signal
of GW detectors. Using the characteristics of some existing detectors, we
demonstrate the capability of the sidereal time analysis to give a clear
signature of different localizations of GW sources: the Galactic Center, the
Galactic Plane, the Supergalactic plane, the Great Attractor. On the contrary,
a homogeneous 3D-distribution of GW sources gives a signal without features. In
this paper we consider tensor gravitational waves with randomly oriented
polarization. We consider GW detectors at fixed positions on the Earth, and a
fixed orientation of the antenna.


title: Asymmetric Explosions of Thermonuclear Supernovae

abstract:
  A type Ia supernova explosion starts in a white dwarf as a laminar
deflagration at the center of the star and soon several hydrodynamic
instabilities (in particular, the Rayleigh-Taylor (R-T) instability) begin to
act. In previous work (Ghezzi, de Gouveia Dal Pino, & Horvath 2001), we
addressed the propagation of an initially laminar thermonuclear flame in
presence of a magnetic field assumed to be dipolar. We were able to show that,
within the framework of a fractal model for the flame velocity, the front is
affected by the field through the quenching of the R-T instability growth in
the direction perpendicular to the field lines. As a consequence, an asymmetry
develops between the magnetic polar and the equatorial axis that gives a
prolate shape to the burning front. We have here computed numerically the total
integrated asymmetry as the flame front propagates outward through the
expanding shells of decreasing density of the magnetized white dwarf
progenitor, for several chemical compositions, and found that a total asymmetry
of about 50 % is produced between the polar and equatorial directions for
progenitors with a surface magnetic field B ~ 5 x 10^{7} G, and a composition
C12 = 0.2 and O16 = 0.8 (in this case, the R-T instability saturates at scales
\~ 20 times the width of the flame front). This asymmetry is in good agreement
with the inferred asymmetries from spectropolarimetric observations of very
young supernova remnants, which have recently revealed intrinsic linear
polarization interpreted as evidence of an asymmetric explosion in several
objects,such as SN1999by, SN1996X, and SN1997dt. Larger magnetic field
strengths will produce even larger asymmetries. We have also found that for
lighter progenitors the total asymmetry is larger.


title: The CERN Axion Solar Telescope (CAST): status and prospects

abstract:
  The CAST experiment is being mounted at CERN. It will make use of a
decommissioned LHC test magnet to look for solar axions through its conversion
into photons inside the magnetic field. The magnet has a field of 9 Tesla and
length of 10 m and is installed in a platform which allows to move it ~8
degrees vertically and ~40 degrees horizontally. According to these numbers we
expect a sensitivity in axion-photon coupling ~5 x 10^-11 GeV^-1 for axion
masses m < ~10^-2 eV, and with a gas filled tube 10^-10 GeV^-1 for m < ~2 eV.


title:
Extended Source Diffraction Effects Near Gravitational Lens Fold
  Caustics

abstract:
  Calculations are presented detailing the gravitational lens diffraction due
to the steep brightness gradient of the limb of a stellar source. The lensing
case studied is the fold caustic crossing. The limb diffraction signal greatly
exceeds that due to the disk as a whole and should be detectable for white
dwarf sources in our Galaxy and it's satellites with existing telescopes.
Detection of this diffraction signal would provide an additional mathematical
constraint, reducing the degeneracy among models of the lensing geometry. The
diffraction pattern provides pico-arcsecond resolution of the limb profile.


title: Carbon-rich, extremely metal-poor Population II stars

abstract:
  A significant fraction of very metal-poor stars have unexpectedly high carbon
abundances. I recap on their discovery, describe the results of high-resolution
spectroscopic studies of their composition, and consider possible origins. It
is now clear that at least two, and possibly three different explanations are
needed for their general characteristics.


title: Stellar collapse and gravitational waves

abstract:
  The new generation of gravitational wave (GW) detectors have the potential to
open a novel window onto the violent dynamics of core collapse. Although it is
certain that core collapse events generate gravitational radiation,
understanding the characteristics of the radiation -- whether it can be
measured with these detectors, and the best way to go about doing so -- is a
challenging problem. In this chapter we review the promise of GWs as
observational probes, including a discussion of the current state of GW
detectors, and discuss the status of work to understand the waves generated by
stellar core collapse.


title:
Future Mm/Submm Instrumentation and Science Opportunities: Example of
  Deuterated Molecules

abstract:
  During the next decade a tremendous advance will take place in
instrumentation for spectroscopy of the interstellar medium. Major new
facilities (ALMA, SOFIA, APEX, LMT, Herschel and others) will be constructed
and commissioned, so that the science opportunities, in the field of
astrochemistry, will increase by a huge factor. This will be enhanced by the
new receivers with greater bandwidth and sensitivity. The new opportunities
will be in the area of astrochemistry of distant objects, through greater
sensitivity, or new spectral ranges due to the platforms above the Earth's
atmosphere. Various aspects of new spectral ranges are discussed, with emphasis
on H2O lines, features previously hidden under H2O or O2 lines, light hydrides
and particularly on deuterium in molecules. Recently, multiply deuterated
species have been detected, e.g. ND3, in cold dense regions of the interstellar
medium. It is argued here that it is possible that so much deuterium could be
trapped, by the fractionation process, into heavy molecules such as ND3,
etc..., and species such as H2D+ and possibly D2H+, that D and HD might be
depleted. This would be the mechanism for the large dispersion of [D]/[H]
values found in the interstellar medium. Light molecules (hydrides and
deuterides) generally have large fundamental rotation frequencies, often lying
in the HIFI bands. The deuterides are a specially suitable case, because the
species exist mainly in cold dense regions, where the molecules are in the
ground states and THz observations will best be carried out by absorption
spectroscopy against background dust continuum sources such as Sgr B2 and W49N.


title:
Origin and interpretation of kilohertz QPOs from strange stars in X-ray
  binary system: theoretical hydrodynamical description

abstract:
  We model and interpret the Kilohertz QPOs from the hydrodynamical description
of accretion disk around a rapidly rotating compact strange star. The higher
QPO frequency is described by the viscous effects of accretion disk leading to
shocks, while the lower one is taken to be the Keplerian motion of the
accreting matter. Comparing our results with the observations for two of the
fastest rotating compact stellar candidates namely, 4U~1636-53 and KS 1731-260,
we find that they match to a very good approximation, thus interpreting them as
strange stars.


title: Have we observed the skin vibration of realistic strange stars (ReSS) ?

abstract:
  Skin vibration of ReSS and consequent resonance absorption can account for
the absorption lines in the spectrum of X-ray emission from many compact
stellar objects and in particular, the stars J1210$-$5226 and RXJ1856$-$3754.
Observations of the X-ray spectrum of these stars is difficult to explain, if
they are neutron stars.


title: A single population scheme for FR I and FR II radio galaxies

abstract:
  The presence of two distant FR I radio galaxies in the Hubble Deep Field plus
Flanking Fields indicates that the number density of these objects is about
10-50 times higher at z>1 than in the local universe. This is in strong
contrast with the idea that FR Is undergo no cosmological evolution. We
advocate that the cosmological evolution of radio sources may be independent of
FR class, and instead solely a function of radio power. In this scenario the
evolutionary properties of extragalactic radio sources can be fully described
within a `single population scheme'.


title:
Dissecting the Homunculus nebula around Eta Carinae with spatially
  resolved near-infrared spectroscopy

abstract:
  Near-infrared emission lines provide unique diagnostics of the geometry,
structure, kinematics, and excitation of eta Carinae's circumstellar ejecta,
and give clues to the nature of its wind. The infrared spectrum is a strong
function of position in eta Car's nebula, with a mix of intrinsic and reflected
emission. Molecular hydrogen traces cool gas and dust in the polar lobes, while
[Fe II] blankets their inner surfaces. These lines reveal the back wall of the
SE polar lobe for the first time, and give the clearest picture yet of the 3-D
geometry. Additionally, collisionally-excited [Fe II] reveals the kinematic
structure of a recently discovered `Little Homunculus' expanding inside the
larger one. Equatorial gas in the `Fan', on the other hand, shows a spectrum
indicating recombination and fluorescent pumping. Some equatorial ejecta glow
in the He I 10830 line, showing evidence for material ejected in the 1890
outburst of eta Car. Closer to the star, the compact `Weigelt blobs' are
marginally resolved, allowing their infrared spectrum to be separated from the
star for the first time. In general, infrared spectra reveal a coherent,
directional dependence of excitation in the Homunculus: polar ejecta are
collisionally excited, whereas equatorial ejecta are dominated by fluorescence
and normal photoexcitation. These are important clues to the geometry of the
central star's UV radiation field. Reflected near-infrared emission lines also
reveal interesting latitudinal dependence in the stellar wind.


title:
Superhumps in Cataclysmic Binaries. XXIII. V442 Ophiuchi and RX
  J1643.7+3402

abstract:
  We report the results of long observing campaigns on two novalike variables:
V442 Ophiuchi and RX J1643.7+3402. These stars have high-excitation spectra,
complex line profiles signifying mass loss at particular orbital phases, and
similar orbital periods (respectively 0.12433 and 0.12056 d). They are
well-credentialed members of the SW Sex class of cataclysmic variables. Their
light curves are also quite complex. V442 Oph shows periodic signals with
periods of 0.12090(8) and 4.37(15) days, and RX J1643.7+3402 shows similar
signals at 0.11696(8) d and 4.05(12) d. We interpret these short and long
periods respectively as a "negative superhump" and the wobble period of the
accretion disk. The superhump could then possibly arise from the heating of the
secondary (and structures fixed in the orbital frame) by inner-disk radiation,
which reaches the secondary relatively unimpeded since the disk is not
coplanar.
  At higher frequencies, both stars show another type of variability:
quasi-periodic oscillations (QPOs) with a period near 1000 seconds. Underlying
these strong signals of low stability may be weak signals of higher stability.
Similar QPOs, and negative superhumps, are quite common features in SW Sex
stars. Both can in principle be explained by ascribing strong magnetism to the
white dwarf member of the binary; and we suggest that SW Sex stars are
borderline AM Herculis binaries, usually drowned by a high accretion rate. This
would provide an ancestor channel for AM Hers, whose origin is still
mysterious.


title: Turbulence in the Interstellar Medium: Energetics and Driving Mechanisms

abstract:
  Interstellar turbulence is expected to dissipate quickly in the absence of
continuous energy input. I examine the energy available for driving the
turbulence from six likely mechanisms: magnetorotational instability,
gravitational instability, protostellar outflows, H II region expansion,
stellar winds, and supernovae. I conclude that supernovae contribute far more
energy than the other mechanisms, and so form the most likely drving mechanism.


title:
Measurement of the Europium Isotope Ratio for the Extremely Metal-Poor,
  r-Process-Enhanced Star CS31082-001

abstract:
  We report the first measurement of the isotope fraction of europium (151Eu
and 153Eu) for the extremely metal-poor, r-process-enhanced star CS31082-001,
based on high-resolution spectra obtained with the Subaru Telescope High
Dispersion Spectrograph. We have also obtained new measurements of this ratio
for two similar stars with previous europium isotope measurements, CS22892-052
and HD115444. The measurements were made using observations of the Eu lines in
these spectra that are most significantly affected by isotope shifts and
hyperfine splitting. The fractions of 151Eu derived for CS31082-001,
CS22892-052, and HD115444 are 0.44, 0.51, and 0.46, respectively, with
uncertainties of about +/-0.1. CS31082-001, the first star with a meaningful
measurement of U outside of the solar system, is known to exhibit peculiar
abundance ratios between the actinide and rare-earth elements (e.g., Th/Eu),
ratios that are significantly different from those for other stars with large
excesses of r-process elements, such as our two comparison objects.
Nevertheless, our analysis indicates that the Eu isotope ratio of CS31082-001
agrees, within the errors, with those of other r-process-enhanced objects, and
with that of solar-system material.


title: Formation and migration of trans-Neptunian objects and asteroids

abstract:
  The evolution of thousands of orbits of Jupiter-family comets and asteroids
under the gravitational influence of planets was calculated. Comparison of the
results obtained by a symplectic method with those obtained by direct
integration showed that a symplectic method is not always good for
investigations of the orbital evolution of such bodies. Basing on the results
of orbital evolution of bodies, we concluded that a considerable portion of
near-Earth objects could have come from the trans-Neptunian region. Some large
trans-Neptunian objects could be formed by the compression of rarefied dust
condensations, but not by the accumulation of smaller planetesimals.


title:
On Some Transonic Aspects of General Relativistic Spherical Accretion
  onto Schwarzschild Black Holes

abstract:
  The equations governing general relativistic, spherically symmetric,
hydrodynamic accretion of polytropic fluid onto black holes are solved in
Schwarzschild metric to investigate some of the transonic properties of the
flow. Only stationary solutions are discussed. For such accretion, it has been
shown that real physical sonic points may form {\it even for flow with $\gamma
< {4/3}$ or $\gamma > {5/3}$}. Behaviour of some flow variables in the close
vicinity of the event horizon are studied as a function of specific energy and
polytropic index of the flow.


title: Cosmic Gamma-Ray Bursts, Their Afterglows, and Their Host Galaxies

abstract:
  This is a review article for the book "Compact Stellar X-Ray Sources",
Editors W. Lewin and M. van der Klis, to be published by Cambridge University
Press in 2003. It covers the phenomenology of cosmic gamma-ray bursts, the
theory of their afterglows, and the observations and interpretation of their
host galaxies.


title: The Crab Nebula: 3-dimensional Modeling

abstract:
  We construct an axisymmetric model for the Crab Nebula. The flow dyamics is
based on the model by Kennel and Coroniti (1984), but we assume that the
kinetic-energy-dominant wind is confined in the equatorial region. We reproduce
spacially resolved spectra which agree well with the Chandra results. However,
the reproduced image is not a ring but lip-shaped. In addition, brightness
contrast between fore and back sides of the ring cannot be reproduced if we
assumes that the sigma-parameter is as small as 10**-3. We suggest that the
nebula field is highly disordered due to for instance magnetic reconnection.
The estimate of sigma can be larger than previously expected.


title: Diffuse Emission from the Galactic Plane and Unidentified EGRET Sources

abstract:
  Diffuse Galactic gamma-ray emission is produced in interactions of cosmic
rays with gas and ambient photon fields and thus provides us with an indirect
measurement of cosmic rays in various locations in the Galaxy. The diffuse
gamma-ray continuum is more intense than expected both at energies below 200
keV and above 1 GeV. The existing models for the high-energy excess are
reviewed in the light of recent TeV gamma-ray measurements of both diffuse
emission and of discrete Galactic sources such as supernova remnants. I
specifically discuss whether particular classes of Galactic objects are
observable as EGRET gamma-ray sources, either by being found among the
unidentified EGRET sources or by contributing to the diffuse emission as
unresolved sources.


title: Bulge formation in very late-type galaxies

abstract:
  The dynamical evolution of super star clusters (SSCs) moving in the
background of a dark matter halo has been investigated as a possible event
responsible for the formation of bulges in late-type spirals. The underlying
physical processes include sinking of SSCs due to the dynamical friction and
stripping of SSCs on their way to the center. Based on the assumption of a
universal density profile for the dark matter halo, and an isothermal model for
the SSCs, our simulations have yielded bulges that are similar in many aspects
to the observational ones. In particular, the derived surface density profiles
can be well fitted by an exponential structure with nuclear cusps, which is
consistent with HST observations.The preliminary simulations with the Burkert
density profile yield very instructive predictions on the bulge formation,
which is surely worth further investigating.


title:
The 2dF QSO Redshift Survey - X. Lensing of Background QSOs by Galaxy
  Groups

abstract:
  We cross-correlate QSOs from the 2dF Survey with galaxy groups. The galaxy
samples are limited to B < 20.5. We use an objective algorithm to detect galaxy
groups. A 3sigma anti-correlation is observed between QSOs and galaxy groups.
This paucity of faint QSOs around groups is neither a selection effect nor due
to restrictions on the placement of 2dF fibres. By observing the colours of
QSOs on the scales of the anti-correlation, we limit dust in galaxy groups,
finding a maximum reddening of E(b_j-r) < 0.012 at the 95% level. The small
amount of dust thus inferred is insufficient to cause the anti-correlation,
supporting the suggestion by Croom & Shanks that the signal is due to
gravitational lensing. The possibility remains that tailored dust models, such
as grey dust, heavy patches of dust or a combination of dust and lensing, could
explain the anti-correlation. Assuming the signal is caused by lensing rather
than dust, we measure the average velocity dispersion of a Singular Isothermal
Sphere that would cause the anti-correlation as around 1150 km/s. Simulations
reject 600 km/s at the 5% significance level. We also model foreground lenses
as NFW haloes and measure the typical mass within 1.5 Mpc/h of the halo centre
as M_{1.5} = (1.2 +/- 0.9) x 10^{15} solarmasses/h. Regardless of whether we
utilise a SIS or NFW dark matter profile, our model favours more mass in groups
than accounted for in a universe with density parameter Omega_m = 0.3. Detailed
simulations and galaxy group redshifts will significantly reduce the current
systematic uncertainties in these $\Omega_m$ estimates. Reducing the remaining
uncertainty will require larger QSO and galaxy group surveys (abridged).


title: A deep VLA survey at 6 cm in the Lockman Hole

abstract:
  We have obtained a deep radio image with the Very Large Array at 6 cm in the
Lockman Hole. The noise level in the central part of the field is about 11
microJy. From these data we have extracted a catalogue of 63 radio sources. The
analysis of the radio spectral index suggests a flattening of the average radio
spectra and an increase of the population of flat spectrum radio sources in the
faintest flux bin. Cross correlation with the ROSAT/XMM X-ray sources list
yields 13 reliable radio/X-ray associations, corresponding to about 21 per cent
of the radio sample. Most of these associations (8 out of 13) are classified as
Type II AGN. Using optical CCD (V and I) and K' band data we found an optical
identification for 58 of the 63 radio sources. This corresponds to an
identification rate of about 92 per cent, one of the highest percentages so far
available. From the analysis of the colour-colour diagram and of the radio flux
- optical magnitude diagram we have been able to select a subsample of radio
sources whose optical counterparts are likely to be high redshift (z>0.5)
early-type galaxies, hosting an Active Galactic Nucleus responsible of the
radio activity. We also find evidence that at these faint radio limits a large
fraction (about 60 per cent) of the faintest optical counterparts (i.e. sources
in the magnitude range 22.5<I<24.5 mag) of the radio sources are Extremely Red
Objects (EROs) with I-K'>4.


title: Cosmological Effects of a Class of Fluid Dark Energy Models

abstract:
  We study the impact of a generalized Chaplygin gas as a candidate for dark
energy on CMB anisotropies. The generalized Chaplygin gas is a fluid component
with an exotic equation of state, $p = - A/\rho^\alpha$ (a polytropic gas with
negative constant and exponent). Such component interpolates in time between
dust and a cosmological constant, with an intermediate behaviour as $p=\alpha
\rho$. Perturbations of this fluid are stable on small scales, but behave in a
very different way with respect to standard quintessence. Moreover, a
generalized Chaplygin gas could also represent an archetypal example of a
phenomenological unified models of dark energy and dark matter. The results
presented here show how the CMB anisotropies induced by this class of models
differ from a $\Lambda$CDM model.


title: The nuclear processes responsible for the CNO synthesis

abstract:
  The abundances of the isotopes of the elements C, N and O are mainly affected
by the cold CNO cycles in non-explosive stellar situations, or by the hot CNO
chains that can develop in certain explosive sites, like classical novae.
Helium burning phases can modify the composition of the ashes of the CNO
transmutations through several $\alpha$-capture reactions, the most famed one
being 12C(a,g)16O. This contribution presents a short review of the purely
nuclear physics limitations imposed on the accuracy of the predicted C, N and O
yields from H-burning in non-explosive stars or novae. This analysis makes
largely use of the NACRE compilation for the rates of the reactions on stable
targets making up the cold CNO cycle. Some more recent rate determinations are
also considered. The analysis of the impact of the rate uncertainties on the
abundance predictions is conducted in the framework of a simple parametric
astrophysical model. These calculations have the virtue of being a guide in the
selection of the nuclear uncertainties that have to be duly analyzed in
detailed model stars, particularly in order to perform meaningful
confrontations between abundance observations and predictions. They are also
hoped to help nuclear astrophysicists pinpointing the rate uncertainties that
have to be reduced most urgently. A limited use of detailed stellar models is
also made for the purpose of some specific illustrations.


title: Newtonian Stellar Models

abstract:
  We investigate static spherically symmetric perfect fluid models in Newtonian
gravity for barotropic equations of state that are asymptotically polytropic at
low and high pressures. This is done by casting the equations into a
3-dimensional regular dynamical system with bounded dependent variables. The
low and high central pressure limits correspond to two 2-dimensional boundary
subsets, described by homology invariant equations for exact polytropes. Thus
the formulation naturally places work about polytropes in a more general
context. The introduced framework yields a visual aid for obtaining qualitative
information about the solution space and is also suitable for numerical
investigations. Last, but not least, it makes a host of mathematical tools from
dynamical systems theory available. This allows us to prove a number of
theorems about the relationship between the equation of state and properties
concerning total masses and radii.


title:
Turbulence in Accretion Disks. Vorticity Generation and Angular Momentum
  Transport via the Global Baroclinic Instability

abstract:
  In this paper we present the global baroclinic instability as a source for
vigorous turbulence leading to angular momentum transport in Keplerian
accretion disks. We show by analytical considerations and three-dimensional
radiation hydro simulations that, in particular, protoplanetary disks have a
negative radial entropy gradient, which makes them baroclinic. Two-dimensional
numerical simulations show that a baroclinic flow is unstable and produces
turbulence. These findings are tested for numerical effects by performing a
simulation with a barotropic initial condition which shows that imposed
turbulence rapidly decays. The turbulence in baroclinic disks transports
angular momentum outward and creates a radially inward bound accretion of
matter. Potential energy is released and excess kinetic energy is dissipated.
Finally the reheating of the gas supports the radial entropy gradient, forming
a self consistent process. We measure accretion rates in our 2D and 3D
simulations of dotM= - 1E-9 - 1E-7 Msun/yr and viscosity parameters of alpha =
1E-4 - 1E-2, which fit perfectly together and agree reasonably with
observations. The turbulence creates pressure waves, Rossby waves, and vortices
in the R-phi plane of the disk. We demonstrate in a global simulation that
these vortices tend to form out of little background noise and to be
long-lasting features, which have already been suggested to lead to the
formation of planets.


title: Studying the Nearby Universe with Chandra

abstract:
  I highlight results from Chandr observations of nearby galaxies, including
the Milky Way. These observations have offered insights into old mysteries and
indications of new high energy astrophysical phenomena and processes that are
yet to be understood.


title: Ionized Disc Models of MCG-6-30-15

abstract:
  Ionized reflection is one of the possible mechanisms proposed to explain the
small short-timescale variability of the MCG-6-30-15 Fe K line. In this
contribution, we show fits of the Ross & Fabian ionized reflection models to
the 325 ks XMM-Newton observation of MCG--6-30-15. It is found that the
spectrum above 2.5 keV can be fitted with a combination of an ionized reflector
from 5 r_g and a neutral reprocessor beyond about 70 r_g. The ionization
parameter of the inner reflector increases as the source brightens.


title: Atmospheric neutrino flux from 3-dimensional simulation

abstract:
  The atmospheric muon and neutrino flux have been simulated using the same
approach which successfully accounted for the recent secondary proton, electron
and positron flux measurements in orbit by the AMS experiment. For the muon
flux, a good agreement is obtained with the CAPRICE and HEAT data for altitudes
ranging from sea level up to about 38 km. The general features of the
calculated atmospheric neutrino flux are reported and discussed. The flux
obtained at the Super-Kamiokande experiment location are reported and compared
with other calculations. For low neutrino energies the flux obtained is
significantly smaller than that used in the data analysis of underground
experiment. The simulation results for the SOUDAN experiment site are also
reported.


title: Lensing by galaxies in CNOC2 fields

abstract:
  We have observed two blank fields of approximately 30 by 23 arcminutes using
the William Herschel Telescope. The fields have been studied as part of the
CNOC2 survey, and spectroscopic redshifts are available for 1125 galaxies in
the two fields. We measured the lensing signal caused by large scale structure,
and found that the result is consistent with current, more accurate
measurements. We study the galaxy-galaxy lensing signal of three overlapping
samples of lenses, and detect a significant signal in all cases. The estimates
for the velocity dispersion of an L* galaxy agree well for the various samples.
The best fit singular isothermal sphere model to the ensemble averaged
tangential distortion around the galaxies with redshifts yields a velocity
dispersion of \sigma_*=130^{+15}_{-17} km/s, in good agreement with other
studies. We use a maximum likelihood analysis, where a parameterized mass model
is compared to the data, to study the extent of galaxy dark matter halos.
Making use of all available data, we find \sigma_*=111\pm12 km/s (68.3%
confidence) for a truncated isothermal sphere model in which all galaxies have
the same mass-to-light ratio. The value of the truncation parameter is not
constrained that well, and we find s_*=260^{+124}_{-73} h^{-1} kpc (68.3%
confidence The galaxy-galaxy lensing analysis allows us to estimate the average
mass-to-light ratio of the field, which can be used to estimate \Omega_m. The
current result, however, depends strongly on the assumed scaling relation for
s.


title: Observational Constraints on Cardassian Expansion

abstract:
  In this work, we have studied the observational constraints on the Cardassian
Model for the dark energy. We have compared the model with existing Supernova
data. The dependence of the location of the Cosmic Microwave Background
Radiation (CMBR) peaks on the parameters of the model have also been studied.
We find, in particular, that observational data arising from Archeops for the
location of the first peak, BOOMERANG for the location of the third peak,
together with the Supernova data, constrain significantly the parameter space.


title:
Differential Simultaneous Imaging and Faint Companions: TRIDENT First
  Results from CFHT

abstract:
  We present the first results obtained at CFHT with the TRIDENT infrared
camera, dedicated to the detection of faint companions close to bright nearby
stars. Its main feature is the acquisition of three simultaneous images in
three wavelengths (simultaneous differential imaging) across the methane
absorption bandhead at 1.6 micron, that enables a precise subtraction of the
primary star PSF while keeping the companion signal. Thirty-five stars have
been observed in two observing missions, with no detection so far. It is shown
that a faint companion with a DeltaH of 10 magnitudes would be detected at 0.5
arcsec from the primary.


title:
Searching for Faint Companions with the TRIDENT Differential
  Simultaneous Imaging Camera

abstract:
  We present the first results obtained at CFHT with the TRIDENT infrared
camera, dedicated to the detection of faint companions close to bright nearby
stars. Its main feature is the acquisition of three simultaneous images in
three wavelengths (simultaneous differential imaging) across the methane
absorption bandhead at 1.6 micron, that enables a precise subtraction of the
primary star PSF while keeping the companion signal. Gl229 and 55Cnc
observations are presented to demonstrate TRIDENT subtraction performances. It
is shown that a faint companion with a DeltaH of 10 magnitudes would be
detected at 0.5 arcsec from the primary.


title:
A deep search for 21cm absorption in high redshift damped Lyman-$\alpha$
  systems

abstract:
  We present deep GMRT 21cm absorption spectra of 10 damped Lyman-$\alpha$
systems (DLAs), of which 8 are at redshifts $z \ga 1.3$. HI absorption was
detected in only one DLA, the $z = 0.5318$ absorber toward PKS 1629+12, which
has been identified with a luminous spiral galaxy; the spin temperature limit
($T_s \le 310$ K) derived from our observations continues the trend of DLAs
associated with bright spirals having low spin temperatures. In 7 of the
remaining 9 systems, the observations place strong lower limits on the spin
temperature of the HI gas.
  The sample of DLAs searched for 21cm absorption now consists of 31 systems,
with $T_s$ estimates available in 24 cases; of these, 16 are at $z < 2$ and 8
at $z > 2$, with 11 (all at $z < 1$) having optical IDs. For the latter 11
systems, we find that all low $T_s$ DLAs have been identified with luminous
galaxies, while all high $T_s$ ($T_s \ga 1000$ K) DLAs have been identified
with either LSBs or dwarfs. DLA spin temperatures thus appear to correlate with
galaxy type, with no correlation seen between $T_s$ and impact parameter.
  The trend that low $z$ DLAs exhibit both high and low $T_s$ values while high
redshift ($z \ga 3$) DLAs only show high spin temperatures is present in this
expanded data set. Based on this difference in spin temperatures, the Gehan
test rules out the hypothesis that DLAs at $z > 2$ and DLAs at $z < 2$ are
drawn from the same parent population at ~ 99 % confidence level.
  Finally, we estimate upper limits on the fraction of cold HI, $f_{CNM}$, in
the $z \ga 3$ DLAs. In local spirals, $f_{CNM} \sim 0.5$; in contrast, we find
that $f_{CNM} < 0.3$ in all 7 high $z$ DLAs, with $f_{CNM} < 0.1$ in 5 of the 7
cases. (abridged)


title: High-density QCD pairing in compact star structure

abstract:
  Strange quark matter in a color flavor locked (CFL) state can be the true
ground state of hadronic matter for a much wider range of the parameters of the
model (the gap of the QCD Cooper pairs $\Delta$, the strange quark mass $m_s$
and the Bag Constant $B$) than the state without any pairing. We review the
equation of state (EOS) of CFL strange matter and study the structure of
stellar objects made up of this phase, highlighting the novel features of the
latter. Although the effects of pairing on the equation of state are thought to
be small, we find that CFL stars may be in fact much more compact than strange
stars (SS). This feature may be relevant in view of some recent observation
claiming the existence of exotic and/or deconfined phases in some nearby
neutron stars (NS).


title:
Protoplanetary Disks in the Orion Nebula: An H$\alpha$ Fabry-Perot study
  and Astrobiological Aspects

abstract:
  In this paper, we present a briefly overview of the protoplanetary disks in
the Orion Nebula, incluiding some astrobiological aspects and an H$\alpha$
Fabry-Perot study of 16 of them. We found that Fabry-Perot interferometry
constitutes an effective technique for the detection of proplyds. We also
report heliocentric systemic velocities for the proplyds 82-336, 158-323,
158-326, 159-350, 161-314, 161-324, 163-317, 166-316, 167-317, 168-326,
170-337, 176-325, 177-341, 180-331, 197-427 and 244-440. The velocities were
measured between 22-38 km s$^{-1}$.


title: Long periodicity of Blazar with RXTE ASM, TA and HEGRA

abstract:
  Long periodicity for Mkn501 during a large flare in 1997 have been reported
by TA, HEGRA group. Here, we establish this periodicity with archival data of
RXTE All Sky Monitor(ASM), Telescope Array(TA) and HEGRA with a chance
probability less than $10^{-5}$. We also find that an origin of 23 day
periodicity is related with a change of either a gamma factor of electrons
$\gamma$ or the magnetic field or a beaming factor. And, in order to search for
a category which have a long periodicity, we make a periodicity analysis for
ten H.B.L. with RXTE ASM. We find a long periodicity for three TeV detected
source, Mkn501, Mkn421 and PKS2155-304. There may exist a relation between an
origin of a long periodicity and an electron acceleration to a TeV range.


title:
The Baldwin Effect and Black Hole Accretion: A Spectral Principal
  Component Analysis of a Complete QSO Sample

abstract:
  A unique set of UV-optical spectrograms of 22 low redshift QSOs are
investigated using principal component analysis. We find three significant
principal components over the broad wavelength range from Ly\alpha to H\alpha.
They together account for about 78% of the sample intrinsic variance. We
present strong arguments that the first principal component represents the
Baldwin effect, relating equivalent widths to the luminosity (i.e. accretion
rate), but only emission-line cores are involved. The second component
represents continuum variations, probably dominated by intrinsic reddening. The
third principal component directly relates QSO UV properties to the optical
principal component 1 found by Boroson & Green (1992). It is the primary cause
of scatter in the Baldwin relationships. It is also directly related to broad
emission-line width and soft X-ray spectral index, and therefore probably
driven by Eddington accretion ratio. We demonstrate how Baldwin relationships
can be derived using our first principal component, virtually eliminating the
scatter caused by the third principal component. This rekindles the hope that
the Baldwin relationships can be used for cosmological study.


title: Concept of new gamma ray detector

abstract:
  We present a concept of a new gamma ray detector in order to observe
undetected TeV gamma ray background. We measure a track of an electron-positron
pair made by a pair creation in a magnet. By using Si as a tracker in a
magnetic field 3 T, an energy range is up to 10 TeV.


title: The CYDER Survey: First Results

abstract:
  We present the Calan-Yale Deep Extragalactic Research (CYDER) Survey. The
broad goals of the survey are the study of stellar populations, the star
formation history of the universe and the formation and evolution of galaxies.
The fields studied include Chandra deep pointings in order to characterize the
X-ray faint populations. Here we present the results on the first fields
studied. We find that the redshift distribution is consistent with that found
in the Chandra Deep Field North. The distribution of hardness ratios is,
however, softer in our sample. We find a high redshift quasar, CXOCY
J125304.0-090737 at z=4.179, which suggests that the abundance of low
luminosity high redshift quasars may be larger than what would be expected from
reasonable extrapolations from the quasar optical luminosity function.


title: Emission Processes of High Energy Gamma Rays from Gamma-Ray Bursts

abstract:
  Synchrotron self-Compton (SSC) process in the reverse shocks of gamma-ray
bursts is suggested to be responsible for the observed prompt high-energy
gamma-ray emissions from several gamma-ray bursts. We find that the SSC
emission from the reverse shocks dominates over other emission processes in
energy bands from tens of MeV to tens of GeV, for a wide range of shock
parameters. This model is favorable for escape of energetic photons from the
emitting regions due to a lower internal pair-production optical depth, as the
characteristic size of the reverse shock region is much larger than that of
internal shocks. We predict that, in this model, the prompt high-energy
emissions are correlated with the prompt optical flashes, which can be test in
the forthcoming GLAST era.


title: The RICH counter of the AMS experiment

abstract:
  The RICH counter of the AMS experiment is described and its expected
performances are discussed. Prototype results are reported.


title:
The SCUBA Bright Quasar Survey II: unveiling the quasar epoch at
  submillimetre wavelengths

abstract:
  We present results of the first systematic search for submillimetre continuum
emission from z=2, radio-quiet, optically-luminous quasars, using the
SCUBA/JCMT. We have observed a homogeneous sample of 57 quasars in the redshift
range 1.5<z<3.0- the epoch during which the comoving density of luminous AGN
peaks- to make a systematic comparison with an equivalent sample at high (z>4)
redshift. The target sensitivity of the survey (3sigma=10mJy at 850um) was
chosen to enable efficient identification of bright submm sources, suitable for
detailed follow-up. 9 targets are detected, with fluxes in the range 7-17mJy.
Although there is a suggestion of variation of submm detectability between z=2
and z=4, this is consistent with the K-correction of a characteristic
far-infrared spectrum. Additionally, the weighted mean fluxes of non-detections
at z=2 and z>4 are comparable.


title: First radius measurements of very low mass stars with the VLTI

abstract:
  e present 4 very low mass stars radii measured with the VLTI using the 2.2
microns VINCI test instrument. The observations were carried out during the
commissioning of the 104-meter-baseline with two 8-meter-telescopes. We measure
angular diameters of 0.7-1.5 mas with accuracies of 0.04-0.11 mas, and for
spectral type ranging from M0V to M5.5V. We determine an empirical mass-radius
relation for M dwarfs based on all available radius measurements. The observed
relation agrees well with theoretical models at the present accuracy level,
with possible discrepancy around 0.5-0.8 Msolar that needs to be confirmed. In
the near future, dozens of M dwarfs radii will be measured with 0.1-1%
accuracy, with the VLTI, thanks to the improvements expected from the near
infrared instrument AMBER. This will bring strong observational constraints on
both atmosphere and interior physics.


title: Ground-based near-infrared imaging of the HD141569 circumstellar disk

abstract:
  We present the first ground-based near-infrared image of the circumstellar
disk around the post-Herbig Ae/Be star HD141569A initially detected with the
HST. Observations were carried out in the near-IR (2.2 $\mu$m) at the Palomar
200-inch telescope using the adaptive optics system PALAO.
  The main large scale asymmetric features of the disk are detected on our
ground-based data. In addition, we measured that the surface brightness of the
disk is slightly different than that derived by HST observations (at 1.1 $\mu$m
and 1.6 $\mu$m). We interpret this possible color-effect in terms of dust
properties and derive a minimal


title: The Non-Thermal Sunyaev-Zel'dovich Effect in Clusters of Galaxies

abstract:
  In this paper we provide a general derivation of the non-thermal (as well as
of the thermal) SZ effect in galaxy clusters which is exact in the Thomson
limit to any approximation order in the optical depth. Such a general
derivation is obtained using the full relativistic formalism and overcoming the
limitations of the Kompaneets and of the single scattering approximations. To
have a consistent description of the SZ effect in clusters containing
non-thermal phenomena, we also evaluate in a consistent way - for the first
time - the total SZ effect produced by a combination of thermal and non-thermal
electron populations residing in the same environment, like is the case in
radio-halo clusters. We discuss both the spectral and the spatial features of
the total SZ effect and we provide specific predictions for a well studied
radio-halo cluster like A2163. We also discuss the overall SZ effect produced
by a combination of different thermal populations residing in the cluster
atmosphere. In this context, we discuss how the combined observations of the
thermal and non-thermal SZ effect provide constraints on the spectrum of the
relativistic electron population and, in turn, on the presence and on the
origin of non-thermal phenomena (radio-halo, hard X-ray, EUV excesses)
occurring in galaxy clusters.


title:
Is there really a Black Hole at the center of NGC 4041? - Constraints
  from gas kinematics

abstract:
  We present HST/STIS spectra of the Sbc spiral galaxy NGC 4041 which were used
to map the velocity field of the gas in its nuclear region. We detect the
presence of a compact (r~0.4" ~40 pc), high surface brightness, rotating
nuclear disk co-spatial with a nuclear star cluster. The disk is characterized
by a rotation curve with a peak to peak amplitude of ~40 km/s and is
systematically blueshifted by 10 - 20 km/s with respect to the galaxy systemic
velocity. With the standard assumption of constant mass-to-light ratio and with
the nuclear disk inclination taken from the outer disk, we find that a dark
point mass of 1(-0.7;+0.6) 10^7 Msun is needed to reproduce the observed
rotation curve. However the observed blueshift suggests the possibility that
the nuclear disk could be dynamically decoupled. Following this line of
reasoning we relax the standard assumptions and find that the kinematical data
can be accounted for by the stellar mass provided that either the central
mass-to-light ratio is increased by a factor of ~2 or that the inclination is
allowed to vary. This model results in a 3 sigma upper limit of 6 10^6 Msun on
the mass of any nuclear black hole. Overall, our analysis only allows us to set
an upper limit of 2 10^7 Msun on the mass of the nuclear black hole. If this
upper limit is taken in conjunction with an estimated bulge B magnitude of
-17.7 and with a central stellar velocity dispersion of 95 km/s, then these
results are not inconsistent with both the MBH-Lsph and the MBH-sigma
correlations. Constraints on black hole masses in spiral galaxies of types as
late as Sbc are still very scarce and therefore the present result adds an
important new datapoint to our understanding of black hole demography.


title: The Wavelength Calibration of the WFC grism

abstract:
  We present the wavelength solution derived for the G800L grism with the Wide
Field Channel from the spectra of two Galactic Wolf-Rayet stars, WR 45 and WR
96. The data were acquired in-orbit during the SMOV tests and the early INTERIM
calibration program. We have obtained an average dispersion of 39.2 A/pix in
the first order, 20.5 A/pix in the second and -42.5 A/pix in the negative first
order. We show that the wavelength solution is strongly field-dependent, with
an amplitude of the variation of about 11% from the center of the WFC aperture
to the corners. The direction of the field-dependence is the diagonal from the
image left top corner (amplifier A) to the bottom right corner (amplifier D).
These trends are observed for all grism orders. We also describe the
calibration files derived from the SMOV and INTERIM data which are used by the
ST-ECF slitless extraction code aXe.


title:
Modelling Charge Coupled Device Readout: Simulation Overview and Early
  Results

abstract:
  The Calibration enhancement effort for the Space Telescope Imaging
Spectrograph (STIS) aims to improve data calibration via the application of
physical modelling techniques.
  We describe here a model of the Charge Transfer process during read-out of
modern Charge Coupled Devices, and its application to data from STIS. The model
draws upon previous investigations of this process and, in particular, the
trapping and emission model developed by Robert Philbrick of Ball Aerospace.
  Early comparison to calibration data is encouraging. Essentially, a physical
description of the STIS CCD combined with the physics of known defects in the
silicon lattice expected to arise in a hostile radiation environment, is enough
to yield results which approximately match real data. Uncertainties remain,
however, in the details of the model and the physical description of STIS.


title: Bias and the power spectrum beyond the turn-over

abstract:
  Threshold biasing of a Gaussian random field gives a linear amplification of
the reduced two point correlation function at large distances. We show that for
standard cosmological models this does not translate into a linear
amplification of the power spectrum (PS) at small k. For standard CDM type
models this means that the``turn-over'' at small k of the original PS
disappears in the PS of the biased field for the physically relevant range of
the threshold parameter. In real space this difference is manifest in the
asymptotic behaviour of the normalised mass variance in spheres of radius R,
which changes from the ``super-homogeneous'' behaviour to a Poisson-like
behaviour.This qualitative change results from the intrinsic stochasticity of
the threshold sampling. While our quantitative results are specific to the
simplest threshold biasing model, we argue that our qualitative conclusions
should be valid generically for any biasing mechanism involving a
scale-dependent amplification of the correlation function. One implication is
that the real-space correlation function will be a better instrument to probe
for the underlying Harrison Zeldovich spectrum in the distribution of visible
matter, as the characteristic asymptotic negative power-law \xi (r) \sim
-r^{-4} tail is undistorted by biasing.


title: Subarcsecond Imaging of Hot Cores with BIMA

abstract:
  We present 1.4-mm BIMA observations with subarcsecond resolution of the
bright dust and molecular line emission from hot cores associated with a sample
of four ultracompact HII regions: G9.62+0.19, G10.47-0.03, G29.96-0.02,
G31.41+0.31. Density power laws can reproduce the observed continuum emission
but break down on scales smaller than 2000 AU. A total of 38 transitions from
18 species are detected, with G10.47 and G31.41 showing the greatest number of
lines. In particular, these sources display emission from two
collisionally-excited transitions of methanol lying more than 950 K above the
ground state. Outflows traced by H2S emission provide evidence for embedded
exciting sources and the observed morphology of molecular lines is consistent
with internal heating of the cores.


title:
A 1.2mm MAMBO/IRAM-30m Study of Dust Emission from optically luminous
  z~2 Quasars

abstract:
  We report 250GHz (1.2mm) observations of redshift 1.8 < z < 2.8 optically
luminous (M_B < -27.0), radio quiet quasars using the Max-Planck Millimeter
Bolometer (MAMBO) array at the IRAM 30-metre telescope. Nine quasars were
detected and for 26 quasars 3-sigma flux density limits in the range 1.8 to
4mJy were obtained. Adopting a typical dust temperature of 45K, the millimeter
emission implies far-infrared (FIR) luminosities of order 10^13 Lo and dust
masses of ~10^8 Mo. Applying a statistical survival analysis to our total
sample of 43 detected and 95 undetected quasars at z~2 and z>4, we find that
there is no apparent difference in the FIR luminosities, hence the star
formation rates, of QSO at z~2 and at 3.6< z <5. This differs from radio
galaxies, for which the FIR luminosity was found to increase with redshift
(Archibald et al. 2001). We furthermore find that there is no strong
correlation between the far-infrared and optical luminosities, confirming
previous results obtained on smaller samples.


title: Spectroscopy of Globular Clusters in the Fornax dwarf galaxy

abstract:
  We present low resolution, integrated Keck spectra of the five globular
clusters (GCs) of the Fornax dwarf spheroidal galaxy. We find a tentative age
spread among the clusters, with the GC H5 younger by 2-3 Gyr than the others.
The clusters generally appear to be very metal-poor ([Fe/H] ~ -1.8), with the
cluster H4 slightly more metal-rich at [Fe/H] = -1.5. We speculate that cluster
H4 is similar to the Galactic GC Ruprecht 106, which lacks the [alpha/Fe]
enhancement typical among metal-poor GCs in the Milky Way. High-resolution
spectroscopy of individual cluster and field stars will be needed to sort out
the surprisingly complex history of GC formation and evolution in this galaxy.


title:
Major Mergers of Haloes, Growth of Massive Black Holes and Evolving
  Luminosity Function of Quasars

abstract:
  We construct a physically motivated analytical model for the quasar
luminosity function, based on the joint star formation and feeding of massive
black holes suggested by the observed correlation between the black hole mass
and the stellar mass of the hosting spheroids. The parallel growth of massive
black holes and host galaxies is assumed to be triggered by major mergers of
haloes. The halo major merger rate is computed in the frame of the extended
Press-Schechter model. The evolution of black holes on cosmological timescales
is achieved by the integration of the governing set of differential equations,
established from a few reasonable assumptions that account for the distinct
(Eddington-limited or supply-limited) accretion regimes. Finally, the typical
lightcurves of the reactivated quasars are obtained under the assumption that,
in such accretion episodes, the fall of matter onto the black hole is achieved
in a self-regulated stationary way. The predicted quasar luminosity function is
compared to the luminosity functions of the 2dF QSO sample and other, higher
redshift data. We find good agreement in all cases, except for z<1 where the
basic assumption of our model is likely to break down.


title: Spacetime-varying couplings and Lorentz violation

abstract:
  Spacetime-varying coupling constants can be associated with violations of
local Lorentz invariance and CPT symmetry. An analytical supergravity cosmology
with time-varying fine-structure constant provides an explicit example.
Estimates are made for some experimental constraints.


title: Arresting Accretion Torques with Gravitational Radiation

abstract:
  Recent theoretical work has made it plausible for neutron stars (NSs) to lose
angular momentum via gravitational radiation on long timescales (around Myrs)
while actively accreting. The gravitational waves (GWs) can either be emitted
via the excitation of r-modes or from a deformed crust. GW emission can thus
intervene to slow-down or halt the otherwise relentless spin-up from accretion.
Prior to this theoretical work (and the measurements of NS rotation rates in
LMXBs) the community was rather confident that an accreting NS would be spun-up
to rotation rates near breakup, motivating searches for sub-millisecond
objects. After only briefly describing the physics of the GW processes, I argue
that the limiting spin frequency might be appreciably lower than the breakup
frequency. Millisecond radio pulsar observers would likely discover the impact
of GW emission as a dropoff in the number of pulsars beyond 600 Hz, and I show
here that the millisecond pulsar inventory in 47 Tuc might already exhibit such
a cutoff. These theoretical ideas will be tested by GW searches with
ground-based interferometers, such as the advanced LIGO instrument proposed for
operation by 2008.


title:
The LXeGRIT Compton Telescope Prototype: Current Status and Future
  Prospects

abstract:
  LXeGRIT is the first prototype of a novel concept of Compton telescope, based
on the complete 3-dimensional reconstruction of the sequence of interactions of
individual gamma rays in one position sensitive detector. This balloon-borne
telescope consists of an unshielded time projection chamber with an active
volume of 400 cm$^2 \times 7$ cm filled with high purity liquid xenon. Four VUV
PMTs detect the fast xenon scintillation light signal, providing the event
trigger. 124 wires and 4 anodes detect the ionization signals, providing the
event spatial coordinates and total energy. In the period 1999 -- 2001, LXeGRIT
has been extensively tested both in the laboratory and at balloon altitude, and
its response in the MeV region has been thoroughly characterized. Here we
summarize some of the results on pre-flight calibration, event reconstruction
techniques, and performance during a 27 hour balloon flight on October 4 -- 5.
We further present briefly the on-going efforts directed to improve the
performance of this prototype towards the requirements for a base module of a
next-generation Compton telescope.


title: Detecting topology in a nearly flat hyperbolic universe

abstract:
  Cosmic microwave background data shows the observable universe to be nearly
flat, but leaves open the question of whether it is simply or multiply
connected. Several authors have investigated whether the topology of a multiply
connect hyperbolic universe would be detectable when 0.9 < Omega < 1. However,
the possibility of detecting a given topology varies depending on the location
of the observer within the space. Recent studies have assumed the observer sits
at a favorable location. The present paper extends that work to consider
observers at all points in the space, and (for given values of Omega_m and
Omega_Lambda and a given topology) computes the probability that a randomly
placed observer could detect the topology. The computations show that when
Omega = 0.98 a randomly placed observer has a reasonable chance (~50%) of
detecting a hyperbolic topology, but when Omega = 0.99 the chances are low
(<10%) and decrease still further as Omega approaches one.


title:
Pseudo-Schwarzschild description of transonic spherical accretion onto
  compact objects

abstract:
  A number of `modified' Newtonian potentials of various forms are available in
the literature which accurately approximate some general relativistic effects
important for studying accretion discs around a Schwarzschild black hole. Such
potentials may be called `pseudo-Schwarzschild' potentials because they nicely
mimic the space-time around a non-rotating/slowly rotating compact object. In
this paper, we examine the validity of the application of some of these
potentials to study the spherically symmetric, transonic, hydrodynamic
accretion onto a Schwarzschild black hole. By comparing the values of various
dynamical and thermodynamic accretion parameters obtained for flows using these
potentials with full general relativistic calculations, we have shown that
though the potentials discussed in this paper were originally proposed to mimic
the relativistic effects manifested in disc accretion, it is quite reasonable
to use most of the potentials in studying various dynamical as well as
thermodynamic quantities for spherical accretion to compromise between the ease
of handling of a Newtonian description of gravity and the realistic situations
described by complicated general relativistic calculations. Also we have shown
that depending on the chosen regions of parameter space spanned by specific
energy ${\cal E}$ and adiabatic index $\gamma$ of the flow, one potential may
have more importance than another and we could identify which potential is the
best approximation for full general relativistic flow in Scwarzschild
space-time for particular values of ${\cal E}$ and $\gamma$.


title: Magnetic fields in AGNs and microquasars

abstract:
  Observations of AGNs and microquasars by ASCA, RXTE, Chandra and XMM-Newton
indicate the existence of wide X-ray emission lines of heavy ionized elements
in their spectra. The emission can arise in the inner parts of accretion discs
where the effects of General Relativity (GR) must be counted, moreover such
effects can dominate. We describe a procedure to estimate an upper limit of the
magnetic fields in the regions where X-ray photons are emitted. We simulate
typical profiles of the iron $K_\alpha$ line in the presence of a magnetic
field and compare them with observational data. As an illustration we find $H <
10^{10} - 10^{11}$ Gs for Seyfert galaxy MCG--6--30--15. Using the perspective
facilities of measurement devices (e.g. Constellation-X mission) a better
resolution of the blue peak structure of iron $K_\alpha$ line will allow to
find the value of the magnetic fields if the latter are high enough.


title:
Gravitational Microlensing and Dark Matter Problem: Results and
  Perspectives

abstract:
  Foundations of standard theory of microlensing are described, namely we
consider microlensing stars in Galactic bulge, the Magellanic Clouds or other
nearby galaxies. We suppose that gravitational microlenses lie between an Earth
observer and these stars. Criteria of an identification of microlensing events
are discussed. We also consider such microlensing events which do not satisfy
these criteria (non-symmetrical light curves, chromatic effects, polarization
effects). We describe results of MACHO collaboration observations towards the
Large Magellanic Cloud (LMC) and the Galactic bulge in detail. Results of EROS
observations towards the LMC and OGLE observations towards the Galactic bulge
are also presented. A comparison of the microlensing theory and observations is
discussed in full.


title:
Doubly Helical Coronal Ejections from Dynamos and their Role in
  Sustaining the Solar Cycle

abstract:
  Two questions about the solar magnetic field might be answered together once
their connection is identified. The first is important for large scale dynamo
theory: what prevents the magnetic backreaction forces from shutting down the
dynamo cycle? The second question is: what determines the handedness of twist
and writhe in magnetized coronal ejecta? Magnetic helicity conservation is
important for answering both questions. Conservation implies that dynamo
generation of large scale writhed structures is accompanied by the oppositely
signed twist along these structures. The latter is associated with the
backreaction force. We suggest that coronal mass ejections (CME's)
simultaneously liberate small scale twist and large scale writhe of opposite
sign, helping to prevent the cycle from quenching and enabling a net magnetic
flux change in each hemisphere. Observations and helicity spectrum measurements
from a simulation of a rising flux ribbon support this idea. We show a new
pictorial of dynamo flux generation that includes the backreaction and magnetic
helicity conservation by characterizing the field as a 2-D ribbon rather than a
1-D line.


title: The Dynamical Evolution of Narrow Line Regions

abstract:
  We review recent progress by the RSAA team in elucidating the dynamical
evolution of the various classes of Narrow Line Regions (NLR) in active
galaxies.


title:
Internal Dust Correction Factors for Star Formation Rates Derived for
  Dusty \HII Regions and Starburst Galaxies

abstract:
  Star formation rates in galaxies are frequently estimated using the Balmer
line fluxes. However, these can be systematically underestimated because dust
competes for the absorption of Lyman continuum photons in the ionized gas. Here
we present theoretical correction factors in a simple analytic form. T These
factors scale as the product of the ionization parameter, ${\cal U}$, and the
nebular O/H abundance ratio, both of which can now be derived from the
observation of bright nebular line ratios. The correction factors are only
somewhat dependent upon the photoelectron production by grains, but are very
sensitive to the presence of complex PAH-like carbonaceous molecules in the
ionized gas, providing that these can survive in such an environment.


title: Fitting Gravitational Lenses: Truth or Delusion

abstract:
  The observables in a strong gravitational lens are usually just the image
positions and sometimes the flux ratios. We develop a new and simple algorithm
which allows a set of models to be fitted exactly to the observations. Taking
our cue from the strong body of evidence that early-type galaxies are close to
isothermal, we assume that the lens is scale-free with a flat rotation curve.
However, our algorithm allows full flexibility as regards the angular structure
of the lensing potential. Importantly, all the free parameters enter linearly
into the model and so the lens and flux ratio equations can always be solved by
straightforward matrix inversion. We use this new algorithm to examine some of
the claims made for substructure on the basis of "anomalous flux ratios". We
demonstrate by explicit construction that some of the lenses for which
substructure has been claimed can be well-fit by smooth lens models. This is
especially the case when the systematic errors in the flux ratios (caused by
microlensing or differential extinction or scatter-broadening) are taken into
account. However, there is certainly one system (B1422+231) for which the
existing smooth models are definitely inadequate and for which substructure may
be implicated. Within a few tens of kpc of galaxy centres, dynamical friction
is efficient at dissolving any substructure. So, little substructure lies
projected within the Einstein radius of most strong lenses. The numbers of
strong lenses for which substructure is currently being claimed may be so large
that this contradicts rather than supports cold dark matter theories.


title: Five Years at the Movies

abstract:
  GAIA is an astrometric satellite which has been approved by the European
Space Agency for launch in about 2010. It will measure the angles between
objects in fields that are separated on the sky by about a radian. Data will
stream continuously at 1 Mbps from GAIA's three telescopes, providing
information on the positions and velocities of the billion or more
astrophysical objects brighter than 20th magnitude. The motion of objects
across the sky caused by their space motion and their parallactic motion, and
the variability of objects in 15 wavebands, will be measured because each
object is observed at least 150 times during the 5 year mission lifetime. From
the raw time series, a three-dimensional movie of the motions of stars in the
Galaxy will be synthesized. The alert despatcher in the GAIA mission will
provide forewarning of many kinds of bursting and variable phenomena. We
discuss two applications of the GAIA movie show in detail here. First, the
astrometric microlensing signal will allow us to take a complete inventory of
all objects -- no matter how dark -- in the solar neighbourhood. Second, the
catalogue of supernovae detections will be the largest ever taken. It will
provide opportunities both for follow-ups in other wavebands and numerous
examples of scarce phenomena (like subluminous SNe).


title:
Some recent developments in gamma-ray burst afterglow and prompt
  emission models

abstract:
  Extensive observational campaigns of afterglow hunting have greatly enriched
our understanding of the gamma-ray burst (GRB) phenomenon. Efforts have been
made recently to explore some afterglow properties or signatures that will be
tested by the on-going or the future observational campaigns yet come. These
include the properties of GRB early afterglows in the temporal domain; the
GeV-TeV afterglow signatures in the spectral domain; as well as a global view
about the GRB universal structured jet configuration. These recent efforts are
reviewed. Within the standard cosmological fireball model, the very model(s)
responsible for the GRB prompt emission is (are) not identified. These models
are critically reviewed and confronted with the current data.