title:
Observing scattered X-ray radiation from gamma-ray bursts: a way to
  measure their collimation angles

abstract:
  There are observational facts and theoretical arguments for an origin of
gamma-ray bursts in molecular clouds in distant galaxies. If this is true, one
could detect a significant flux of GRB prompt and early afterglow X-ray
radiation scattered into our line of sight by the molecular and atomic matter
located within tens of parsecs of the GRB site long after the afterglow has
faded away. The scattered flux directly measures the typical density of the GRB
ambient medium. Furthemore, if the primary emission is beamed, the scattered
X-ray flux will be slowly decreasing for several months to years before falling
off rapidly. Therefore, it should be possible to estimate the collimation angle
of a burst from the light curve of its X-ray echo and a measured value of the
line-of-sight absorption column depth. It is shown that detection of such an
echo is for the brightest GRBs just within the reach of the Chandra and
XMM-Newton observatories.


title: Moment equations for chemical reactions on interstellar dust grains

abstract:
  While most chemical reactions in the interstellar medium take place in the
gas phase, those occurring on the surfaces of dust grains play an essential
role. Chemical models based on rate equations including both gas phase and
grain surface reactions have been used in order to simulate the formation of
chemical complexity in interstellar clouds. For reactions in the gas phase and
on large grains, rate equations, which are highly efficient to simulate, are an
ideal tool. However, for small grains under low flux, the typical number of
atoms or molecules of certain reactive species on a grain may go down to order
one or less. In this case the discrete nature of the opulations of reactive
species as well as the fluctuations become dominant, thus the mean-field
approximation on which the rate equations are based does not apply. Recently, a
master equation approach, that provides a good description of chemical
reactions on interstellar dust grains, was proposed. Here we present a related
approach based on moment equations that can be obtained from the master
equation. These equations describe the time evolution of the moments of the
distribution of the population of the various chemical species on the grain. An
advantage of this approach is the fact that the production rates of molecular
species are expressed directly in terms of these moments. Here we use the
moment equations to calculate the rate of molecular hydrogen formation on small
grains. It is shown that the moment equation approach is efficient in this case
in which only a single reactive specie is involved. The set of equations for
the case of two species is presented and the difficulties in implementing this
approach for complex reaction networks involving multiple species are
discussed.


title: How many Hipparcos Variability-Induced Movers are genuine binaries?

abstract:
  Hipparcos observations of some variable stars, and especially of long-period
(e.g. Mira) variables, reveal a motion of the photocenter correlated with the
brightness variation ({variability-induced mover -- VIM), suggesting the
presence of a binary companion. A re-analysis of the Hipparcos photometric and
astrometric data does not confirm the VIM solution for 62 among the 288 VIM
objects (21%) in the Hipparcos catalogue. Most of these 288 VIMs are
long-period (e.g. Mira) variables (LPV). The effect of a revised chromaticity
correction, which accounts for the color variations along the light cycle, was
then investigated. It is based on `instantaneous' $V-I$ color indices derived
from Hipparcos and Tycho-2 epoch photometry. Among the 188 LPVs flagged as VIM
in the Hipparcos catalogue, 89 (47%) are not confirmed as VIM after this
improved chromaticity correction is applied. This dramatic decrease in the
number of VIM solutions is not surprising, since the chromaticity correction
applied by the Hipparcos reduction consortia was based on a fixed $V-I$ color.
Astrophysical considerations lead us to adopt a more stringent criterion for
accepting a VIM solution (first-kind risk of 0.27% instead of 10% as in the
Hipparcos catalogue). With this more severe criterion, only 27 LPV stars remain
VIM, thus rejecting 161 of the 188 (86%) of the LPVs defined as VIMs in the
Hipparcos catalogue.


title:
Prospects for High Energy Studies of Pulsars with the AGILE Gamma-Ray
  Telescope

abstract:
  AGILE is a small gamma-ray astronomy satellite, with good spatial resolution,
excellent timing capabilities and an unprecedented large field of view (~1/5 of
the sky). It will be the next mission dedicated to high energy astrophysics in
the range 30 MeV-50 GeV, and will be launched in 2005. Pulsars are a major
topic of investigation of AGILE and, besides studying the small sample of known
objects, AGILE will offer the first possibility of detecting several young and
energetic radio pulsars that have been discovered since the end of the CGRO
mission. We provide an estimate of the expected number of detectable gamma-ray
pulsars and present AGILE capabilities for timing analysis with small counting
statistics, based on the analysis of data from simulations, from the EGRET
archive, and from radio pulsar catalogs.


title: Do spherical alpha^2-dynamos oscillate?

abstract:
  The question is answered whether kinematic alpha^2-shell-dynamos are able to
produce a cyclic activity or not. The alpha-effect is allowed to be
latitudinally inhomogeneous and/or anisotropic, but it is assumed as radially
uniform in the turbulent shell.
  For a symmetric alpha-tensor we only find oscillatory solutions if i) the
alpha_zz vanishes or is of the opposite sign as alpha_{phi phi}, ii) the
alpha-effect is strongly concentrated to the equatorial region and iii) the
alpha-effect is concentrated to a rather thin outer shell. In the other cases
almost always the nonaxisymmetric field mode S1 possesses the lowest dynamo
number which slowly drifts along the azimuthal direction. Also uniform but
anisotropic alpha-effect (alpha_zz = 0) leads to the nonaxisymmetric solutions
as it is confirmed by the Karlsruhe dynamo experiment. However, one of the
antisymmetric parts of the alpha-tensor basically plays the role of a
differential rotation in the induction equation. Using for the radial profile
of this effect the results of anumerical simulation for the alpha-tensor of the
solar convection zone, one indeed finds the possibility of oscillating
alpha^2-dynamos even without the existence of real nonuniform plasma rotation.


title: The Component Star Masses in RW Tri

abstract:
  We use time-resolved spectra of the cataclysmic variable RW Tri in the I and
K-band to determine the orbital velocity of the secondary star using skew
mapping and cross correlation techniques respectively. We find radial velocity
amplitudes of 250+/-47km/s in the I-band, and 221+/-29km/s in the K-band. We
also determine the rotational velocity of the secondary star using the K-band
data and find a V(rot)sini of 120+/-20km/s. A combination of these results
coupled with an estimate of the effect of heating on the secondary star
suggests a mass ratio M_2/M_1 in the range 0.6-1.1; the mass ratio range with
no correction for heating is 0.5-0.8. These lead to most likely estimates of
the primary and secondary star masses in the range 0.4-0.7 solar mass and
0.3-0.4 solar mass respectively. Further refinement of the stellar masses is
hampered by uncertain knowledge of the white dwarf orbital velocity, and we
discuss evidence that at least some estimates of the white dwarf velocity are
contaminated by non-orbital components.


title: Statistical mechanics of violent relaxation in stellar systems

abstract:
  We discuss the statistical mechanics of violent relaxation in stellar systems
following the pioneering work of Lynden-Bell (1967). The solutions of the
gravitational Vlasov-Poisson system develop finer and finer filaments so that a
statistical description is appropriate to smooth out the small-scales and
describe the ``coarse-grained'' dynamics. In a coarse-grained sense, the system
is expected to reach an equilibrium state of a Fermi-Dirac type within a few
dynamical times. We describe in detail the equilibrium phase diagram and the
nature of phase transitions which occur in self-gravitating systems. Then, we
introduce a small-scale parametrization of the Vlasov equation and propose a
set of relaxation equations for the coarse-grained dynamics. These relaxation
equations, of a generalized Fokker-Planck type, are derived from a Maximum
Entropy Production Principle (MEPP). We make a link with the quasilinear theory
of the Vlasov-Poisson system and derive a truncated model appropriate to
collisionless systems subject to tidal forces. With the aid of this kinetic
theory, we qualitatively discuss the concept of ``incomplete relaxation'' and
the limitations of Lynden-Bell's theory.


title: Galaxies at z=3 around Damped Ly-alpha Clouds

abstract:
  We are exploring the connection between damped Ly-alpha absorbers (DLAs) and
Lyman break galaxies (LBGs) using deep -- (5sigma)=26 m_{AB}-- broad band
imaging (UBVI) of four wide fields (0.25 sq. deg. each) obtained at the Kitt
Peak 4-m telescope with MOSAIC. Each field contains a damped system at z=3.
  We want to address the nature of DLAs at high-redshifts: (1) Are they
embedded in much larger systems of galaxies? (2) How does the spatial
distribution of LBGs in 3D (space and redshift) correlate with the absorber?
Contrary to most previous DLA studies, we are not looking for the absorber, and
we do not rely on control fields because each of our fields is 40 Mpc
(co-moving) on a side. We present preliminary results in two of our fields. In
one case, we see an indication of an overdensity of galaxies on a scale of 5
Mpc. We discuss the possible implications and sources of contamination of our
results.


title: On bending angles by gravitational lenses in motion

abstract:
  The bending of lightrays by the gravitational field of a ``lens'' that is
moving relative to the observer is calculated within the approximation of weak
fields, small angles and thin lenses. Up to first order in $v/c$ -- and
assuming the acceleration to be much smaller than $v/c$ -- the bending angle,
time delay and redshift of the images are found to be affected by the component
of the speed of the deflector along the line of sight. The correction takes the
form of an overall factor of $1+v/c$ accompanying the mass of the deflector,
leading to an indeterminacy of the order of $v/c$ in the mass of the lens
inferred on the basis of the separation of multiple images. The consequent
correction to the microlensing lightcurve is pointed out, as well as scenarios
where the correction is potentially relevant.


title: Calibration of Geometric Distortion in the ACS Detectors

abstract:
  The off-axis location of the Advanced Camera for Surveys (ACS) is the chief
(but not sole) cause of strong geometric distortion in all detectors: the Wide
Field Camera (WFC), High Resolution Camera (HRC), and Solar Blind Camera (SBC).
Dithered observations of rich star cluster fields are used to calibrate the
distortion. We describe the observations obtained, the algorithms used to
perform the calibrations and the accuracy achieved.


title: Cosmic Crystallography of the Second Order

abstract:
  The cosmic crystallography method of Lehoucq et al. [1] produces sharp peaks
in the distribution of distances between the images of cosmic sources. But the
method cannot be applied to universes with compact spatial sections of negative
curvature. We apply to these a second order crystallographic effect, as
evidenced by statistical parameters.


title:
Maximum-likelihood astrometric geometry calibration of interferometric
  telescopes: application to the Very Small Array

abstract:
  Interferometers require accurate determination of the array configuration in
order to produce reliable observations. A method is presented for finding the
maximum-likelihood estimate of the telescope geometry, and of other
instrumental parameters, astrometrically from the visibility timelines obtained
from observations of celestial calibrator sources. The method copes
systematically with complicated and unconventional antenna and array
geometries, with electronic bandpasses that are different for each antenna
radiometer, and with low signal-to-noise ratios for the calibrators. The
technique automatically focusses on the geometry errors that are most
significant for astronomical observation. We apply this method to observations
made with the Very Small Array and constrain some 450 telescope parameters,
such as the antenna positions, effective observing frequencies and correlator
amplitudes and phase shifts; this requires only ~ 1 h of CPU time on a typical
workstation.


title: Formation of Binary Pulsars in Globular Clusters

abstract:
  Close to 70 radio pulsars have now been discovered in 23 globular clusters,
with a record 22 pulsars observed in 47 Tuc alone. Accurate timing solutions,
including positions in the cluster, are known for many of the pulsars. These
recent observations provide a unique opportunity to re-examine theoretically
the formation and evolution of recycled pulsars in globular clusters. This
brief review focuses on dynamical exchange interactions between neutron stars
and primordial binaries, through which neutron stars can acquire
intermediate-mass binary companions. The later evolution of these
intermediate-mass binaries leads naturally to the two main types of binary
millisecond pulsars observed in clusters.


title: Double-periodic blue variables in the Magellanic Clouds

abstract:
  We report the discovery, based on an inspection of the OGLE-II database, of a
group of blue variables in the Magellanic Clouds showing simultaneously two
kinds of photometric variability: a short-term cyclic variability with typical
amplitude $\Delta I \sim$ 0.05 mag and period $P_{1}$ between 4 and 16 days and
a sinusoidal, long-term cyclic oscillation with much larger amplitude $\Delta I
\sim$ 0.2 mag with period $P_{2}$ in the range of 150-1000 days. We find that
both periods seems to be coupled through the relationship $P_{2}$ = 35.2 $\pm$
0.8 $P_{1}$. In general, the short term variability is reminiscent of those
shown by Algol-type binaries. We propose that the long-term oscillation could
arise in the precession of a elliptical disc fed by a Roche-lobe filling
companion in a low mass ratio Algol system.


title:
The Evolution Of LMC X-4 Flares: Evidence For Super-Eddington Radiation
  Oozing Through Inhomogeneous Polar Cap Accretion Flows ?

abstract:
  We present the results of two extensive Rossi X-ray Timing Explorer
observations of large X-ray flaring episodes from the high-mass X-ray binary
pulsar LMC X-4. Light curves during the flaring episodes comprise bright peaks
embedded in relatively fainter regions, with complex patterns of recurrence and
clustering of flares. We identify precursors preceding the flaring activity.
Pulse profiles during the flares appear to be simple sinusoids, and pulsed
fractions are proportional to the flare intensities. We fit Gaussian functions
to flare peaks to estimate the mean full-width-half-maximum to be $\sim$68 s.
Significant rapid aperiodic variability exists up to a few hertz during the
flares, which is related to the appearance of narrow, spiky peaks in the light
curves. While spectral fits and softness ratios show overall spectral softening
as the flare intensity increases, the narrow, spiky peaks do not follow this
trend. The mean fluence of the flare peaks is (3.1 $\pm$ 2.9) $\times$
10$^{40}$ ergs in the 2.5--25 keV energy range, with its maximum at $\sim$1.9
$\times$ 10$^{41}$ ergs. The flare peak luminosity reaches up to (2.1 $\pm$
0.2) $\times$ 10$^{39}$ ergs s$^{-1}$, far above the Eddington luminosity of a
neutron star. We discuss possible origins of the flares, and we also propose
that inhomogeneous accretion columns onto the neutron star polar caps are
responsible for the observed properties.


title: A radial mass profile analysis of the lensing cluster MS2137-23

abstract:
  We reanalyze the strong lens modeling of the cluster of galaxies MS2137-23
using a new data set obtained with the ESO VLT. We found the photometric
redshifts of the two main arc systems are both at z=1.6. After subtraction of
the central cD star light of the HST image we found that only one object lying
underneath has the expected properties of the fifth image associated to the
tangential arc. We improve the previous lens modelings of the central dark
matter distribution of the cluster, using an isothermal model with a core (IS)
and the NFW-like model with a cusp. Without the fifth image, the arc properties
together with the shear map profile are equally well fit by the and by an IS
and a sub-class of generalized-NFW mass profiles having inner slope power index
in the range 0.7<alpha<1.2. Adding new constrains provided by the fifth image
favors IS profiles that better predict the fifth image properties. A model
including cluster galaxy perturbations or the the stellar mass distribution
does not change our conclusions but imposes the M/L_I of the cD stellar
component is below 10 at a 99% confidence level.
  Using our new detailed lensing model together with Chandra X-ray data and the
cD stellar component we finally discuss intrinsic properties of the
gravitational potential. Whereas X-ray and dark matter have a similar shape at
various radius, the cD stellar isophotes are twisted by 13 deg. The sub-
arc-second azimuthal shift we observe between the radial arc position and the
predictions of elliptical models correspond to what is expected from a mass
distribution twist. This shift may result from a projection effect of the cD
and the cluster halos, thus revealing the triaxiality of the system.


title:
Spectrophotometry with a transmission grating for detecting faint
  occultations

abstract:
  High-precision spectrophotometry is highly desirable in detecting and
characterizing close-in extrasolar planets to learn about their makeup and
temperature. For such a goal, a modest-size telescope with a simple
low-resolution spectroscopic instrument is potentially as good or better than a
complex general purpose spectrograph since calibration and removal of
systematic errors is expected to dominate. We use a transmission grating placed
in front of an imaging CCD camera on Steward Observatory's Kuiper 1.5 m
telescope to provide a high signal-to-noise, low dispersion visible spectrum of
the star HD 209458. We attempt to detect the reflected light signal from the
extra-solar planet HD 209458b by differencing the signal just before and after
secondary occultation. We present a simple data reduction method and explore
the limits of ground based low-dispersion spectrophotometry with a diffraction
grating. Reflected light detection levels of 0.1% are achievable for
5000-7000A, too coarse for useful limits on ESPs but potentially useful for
determining spectra of short-period binary systems with large (Delta m_vis=6)
brightness ratios. Limits on the precison are set by variations in atmospheric
seeing in the low-resolution spectrum. Calibration of this effect can be
carried out by measurement of atmospheric parameters from the observations
themselves, which may allow the precision to be limited by the noise due to
photon statistics and atmospheric scintillation effects.


title: Neutrino Mass and Dark Energy from Weak Lensing

abstract:
  Weak gravitational lensing of background galaxies by intervening matter
directly probes the mass distribution in the universe. This distribution, and
its evolution at late times, is sensitive to both the dark energy, a negative
pressure energy density component, and neutrino mass. We examine the potential
of lensing experiments to measure features of both simultaneously. Focusing on
the radial information contained in a future deep 4000 square degree survey, we
find that the expected (1-sigma) error on a neutrino mass is 0.1 eV, if the
dark energy parameters are allowed to vary. The constraints on dark energy
parameters are similarly restrictive, with errors on w of 0.09. Much of the
restrictive power on the dark energy comes not from the evolution of the
gravitational potential but rather from how distances vary as a function of
redshift in different cosmologies.


title: Pseudo-Schwarzschild Description of Accretion-Powered Spherical Outflow

abstract:
  Using two different pseudo-Schwarzschild potentials proposed by Artemova et.
al,$^{1}$ we formulate and solve the equations governing spherically symmetric
transonic inflow and outflow in presence of a relativistic hadronic pressure
mediated steady, standing, spherical shock around the central compact object
and then we self-consistently connect the accretion-wind solutions to calculate
the mass outflow rate $R_{\dot m}$ in terms of minimum number of flow
parameters. Also we study the dependence of this rate on various boundary
conditions governing the flow.


title: Cosmology with coalescing massive black holes

abstract:
  The gravitational waves generated in the coalescence of massive binary black
holes will be measurable by LISA to enormous distances. Redshifts z~10 or
larger (depending somewhat on the mass of the binary) can potentially be probed
by such measurements, suggesting that binary coalescences can be made into
cosmological tools. We discuss two particularly interesting types of probes.
First, by combining gravitational-wave measurements with information about the
universe's cosmography, we can study the evolution of black hole masses and
merger rates as a function of redshift, providing information about the growth
of structures at high redshift and possibly constraining hierarchical merger
scenarios. Second, if it is possible to associate an ``electromagnetic''
counterpart with a coalescence, it may be possible to measure both redshift and
luminosity distance to an event with less than ~1% error. Such a measurement
would constitute an amazingly precise cosmological standard candle.
Unfortunately, gravitational lensing uncertainties will reduce the quality of
this candle significantly. Though not as amazing as might have been hoped, such
a candle would nonetheless very usefully complement other distance-redshift
probes, in particular providing a valuable check on systematic effects in such
measurements.


title: Low-Mass Cluster Galaxies: A Cornerstone of Galaxy Evolution

abstract:
  Low-mass cluster galaxies are the most common galaxy type in the universe and
are at a cornerstone of our understanding of galaxy formation, cluster
luminosity functions, dark matter and the formation of large scale structure. I
describe in this summary recent observational results concerning the properties
and likely origins of low-mass galaxies in clusters and the implications of
these findings in broader galaxy formation issues.


title:
Time-series Spectroscopy of Pulsating sdB stars III: Line Indices of
  PG1605+072

abstract:
  We present the detection and analysis of line index variations in the
pulsating sdB star PG 1605+072. We have found a strong dependence of line index
amplitude on Balmer line order, with high-order Balmer line amplitudes up to 10
times larger than H-beta. Using a simple model, we have found that the line
index may not only be dependent on temperature, as is usually assumed for
oscillating stars, but also on surface gravity. This information will provide
another set of observables that can be used for mode identification of sdBs.


title: Distribution of star-forming complexes in dwarf irregular galaxies

abstract:
  We study the distribution of bright star-forming complexes in a homogeneous
sample of 72 late-type (``irregular'') dwarf galaxies located within the 10 Mpc
volume. Star-forming complexes are identified as bright lumps in B-band galaxy
images and isolated by means of the unsharp-masking method. For the sample as a
whole the radial number distribution of bright lumps largely traces the
underlying exponential-disk light profiles, but peaks at a 10 percent smaller
scale length. Moreover, the presence of a tail of star forming regions out to
at least six optical scale lengths provides evidence against a systematic star
formation truncation within that galaxy extension. Considering these findings,
we apply a scale length-independent concentration index, taking into account
the implied non-uniform random spread of star formation regions throughout the
disk. The number profiles frequently manifest a second, minor peak at about two
scale lengths. Relying on a two-dimensional stochastic self-propagating star
formation model, we show these secondary peaks to be consistent with triggered
star formation; for a few of the brighter galaxies a peculiar peak distribution
is observed that is conceivably due to the onset of shear provided by
differential rotation. On scales between 100 and 1000 pc, and by taking into
account exponential-disk structure, bright lumps reveal cluster dimensions
between 1.3 and 2, with a weak trend to higher dimensions for brighter
galaxies. Interpreting cluster dimension in terms of porosity of a self-similar
intragalactic medium, we derive a relation between current star formation rate,
scale length, and porosity.


title: Galaxy Pairs in the 2dF Survey I. Effects of Interactions in the Field

abstract:
  We study galaxy pairs in the field selected from the 100 K public release of
the 2dF galaxy redshift survey. Our analysis provides a well defined sample of
1258 galaxy pairs, a large database suitable for statistical studies of galaxy
interactions in the local universe, $z \le 0.1$. Galaxy pairs where selected by
radial velocity ($\Delta V$) and projected separation ($r_{\rm p}$) criteria
determined by analyzing the star formation activity within neighbours
(abridged). The ratio between the fractions of star forming galaxies in pairs
and in isolation is a useful tools to unveil the effects of having a close
companion. We found that about fifty percent of galaxy pairs do not show signs
of important star formation activity (independently of their luminosities)
supporting the hypothesis that the internal properties of the galaxies play a
crucial role in the triggering of star formation by interactions.


title: Simulating Cosmic Microwave Background maps in multi-connected spaces

abstract:
  This article describes the computation of cosmic microwave background
anisotropies in a universe with multi-connected spatial sections and focuses on
the implementation of the topology in standard CMB computer codes. The key
ingredient is the computation of the eigenmodes of the Laplacian with boundary
conditions compatible with multi-connected space topology. The correlators of
the coefficients of the decomposition of the temperature fluctuation in
spherical harmonics are computed and examples are given for spatially flat
spaces and one family of spherical spaces, namely the lens spaces. Under the
hypothesis of Gaussian initial conditions, these correlators encode all the
topological information of the CMB and suffice to simulate CMB maps.


title:
Magnetic Fields in Massive Stars. II. The Buoyant Rise of Magnetic Flux
  Tubes Through the Radiative Interior

abstract:
  We present results from an investigation of the dynamical behavior of buoyant
magnetic flux rings in the radiative interior of a uniformly rotating
early-type star. Our physical model describes a thin, axisymmetric, toroidal
flux tube that is released from the outer boundary of the convective core, and
is acted upon by buoyant, centrifugal, Coriolis, magnetic tension, and
aerodynamic drag forces. We find that rings emitted in the equatorial plane can
attain a stationary equilibrium state that is stable with respect to small
displacements in radius, but is unstable when perturbed in the meridional
direction. Rings emitted at other latitudes travel toward the surface along
trajectories that largely parallel the rotation axis of the star. Over much of
the ascent, the instantaneous rise speed is determined by the rate of heating
by the absorption of radiation that diffuses into the tube from the external
medium. Since the time scale for this heating varies like the square of the
tube cross-sectional radius, for the same field strength, thin rings rise more
rapidly than do thick rings. For a reasonable range of assumed ring sizes and
field strengths, our results suggest that buoyancy is a viable mechanism for
bringing magnetic flux from the core to the surface, being capable of
accomplishing this transport in a time that is generally much less than the
stellar main sequence lifetime.


title: Some aspects of primordial black hole physics

abstract:
  Small black holes should have formed in the early Universe if the density
contrast was high enough. This article aims at giving a - biased and partial -
short overview of the latest breakthroughs in this field. It first deals with
tentative experimental detections thanks to gamma-rays and cosmic-rays.
Primordial black holes (PBHs) are then considered as probes of the very small
cosmological scales, far beyond any other classical observable. Finally, some
possible "new physics" effects are considered, especially in the framework of
higher dimensions.


title: Hot Stars: Old-Fashioned or Trendy?

abstract:
  Spectroscopic analyses with the intention of the interpretation of the
UV-spectra of the brightest stars as individuals - supernovae - or as
components of star-forming regions - massive O stars - provide a powerful tool
with great astrophysical potential for the determination of extragalactic
distances and of the chemical composition of star-forming galaxies even at high
redshifts.
  The perspectives of already initiated work with the new generation of tools
for quantitative UV-spectroscopy of Hot Stars that have been developed during
the last two decades are presented and the status of the continuing effort to
construct corresponding models for Hot Star atmospheres is reviewed.
  Because the physics of the atmospheres of Hot Stars are strongly affected by
velocity expansion dominating the spectra at all wavelength ranges,
hydrodynamic model atmospheres for O-type stars and explosion models for
Supernovae of Type Ia are necessary as basis for the synthesis and analysis of
the spectra. It is shown that stellar parameters, abundances and stellar wind
properties can be determined by the methods of spectral diagnostics already
developed. Additionally, it will be demonstrated that models and synthetic
spectra of Type Ia Supernovae of required quality are already available that
make it possible to tackle the question of whether Supernovae Ia are standard
candles in a cosmological sense and the SN-luminosity distances thus indicate
accelerated expansion of the universe.


title:
Gas Flow Structure in Binary Systems with Mass Exchange Driven by
  Stellar Wind

abstract:
  Results of calculations of the flow structure in binary systems with mass
exchange driven by stellar wind are presented. 2D simulations have been carried
out using the Roe-Oscher scheme. The fine grid we used allowed us to detect the
details of the flow structure. In particular, it was found out that solutions
with the wind velocity V of the order of the orbital velocity of the system Vs
are unstable: in solutions with V<Vs -- the steady accretion disk takes place
and if V>Vs -- the cone shock forms. Consideration of the minor variations of
the wind velocity V around Vs shows that they can influence greatly the flow
structure causing transition from disk accretion to the accretion from the
flow. During the flow rearrangement period (the accretion disk destruction) the
accretion rate increases in dozens times for a short time (~0.1 of the orbital
period of the system). This change can result in the drop-off of the gas from
the accretor that is usually associated with activity in these systems.


title:
Prospects for detecting neutral hydrogen using 21cm radiation from large
  scale structure at high redshifts

abstract:
  We estimate the signal from large scale structure at high redshifts in
redshifted 21cm line. We focus on z ~ 3 and the LCDM cosmology. We assume that
neutral hydrogen is to be found only in galaxies, and normalise the total
content to the density parameter of neutral hydrogen in damped Lyman alpha
absorption systems (DLAS). We find that the rms fluctuations due to the large
scale distribution of galaxies is very small and cannot be observed at angular
scales probed by present day telescopes. We have used the sensitivity of the
Giant meter-wave Radio Telescope (GMRT) for comparison. We find that
observations stretching over 1000hours will be required for a 3 sigma detection
of such objects.


title:
Improved Measurement of the Angular Power Spectrum of Temperature
  Anisotropy in the CMB from Two New Analyses of BOOMERANG Observations

abstract:
  We report the most complete analysis to date of observations of the Cosmic
Microwave Background (CMB) obtained during the 1998 flight of BOOMERANG. We use
two quite different methods to determine the angular power spectrum of the CMB
in 20 bands centered at l = 50 to 1000, applying them to 50% more data than has
previously been analyzed. The power spectra produced by the two methods are in
good agreement with each other, and constitute the most sensitive measurements
to date over the range 300 < l < 1000. The increased precision of the power
spectrum yields more precise determinations of several cosmological parameters
than previous analyses of BOOMERANG data. The results continue to support an
inflationary paradigm for the origin of the universe, being well fit by a 13.5
Gyr old, flat universe composed of approximately 5% baryonic matter, 30% cold
dark matter, and 65% dark energy, with a scale invariant initial density
perturbations.


title:
Origin of the 6.85 micron band near young stellar objects: The ammonium
  ion (NH4+) revisited

abstract:
  We have investigated whether the nu_4 feature of NH4+ is a viable candidate
for the 6.85 micron absorption band seen towards embedded young stellar
objects. To produce NH4+ astrophysical ice analogs consisting of H2O, CO2, NH3
and O2 were UV photolysed. The IR spectra reveal peaks that are identified with
the NH4+, NO2-, NO3- and HCO3- ions. It is shown that the NH4+ matches two
absorption features that are observed towards embedded young stellar objects,
i.e., the strong 6.85 micron feature and the 3.26 micron feature. The
characteristic redshift with temperature of the interstellar 6.85 micron
feature is well reproduced. The abundance of NH4+ in interstellar ices would be
typically 10 % relative to H2O. The experiments show that the counterions
produce little distinct spectral signature but rather a pseudo-continuum if a
variety of them is present in a H2O dominated environment. The anions could
therefore go undetected in IR spectra of interstellar ice. In the ISM, where
additional mechanisms such as surface chemistry and additional elements such as
sulfur are available many acids and an even wider variety of anions could be
produced. These components may be detectable once the ices sublime, e.g, in hot
cores.


title: AGNs among ROSAT Blank Field Sources

abstract:
  We selected a sample of sources with high X-ray over optical flux ratio from
the ROSAT PSPC archives. Out of the 16 sources in our sample, one is a
(possibly extreme) BL Lac and two are AGNs. Six more sources are tentatively
classified as AGNs on the basis of their X-ray properties and of our optical-IR
imaging. For one of the AGNs and for the AGN-like blanks we find a discrepancy
between the lack of absorption indicated by the X-ray spectra and the presence
of red counterparts in their error circles. We discuss various possibilities to
reconcile the X-ray and optical information.


title:
Lobe Advance Velocities in the Extragalactic Compact Symmetric Object 4C
  31.04

abstract:
  We report on the results of a two epoch study of the low power Compact
Symmetric Object 4C 31.04. Observations performed with the VLBA at 5 GHz in
1995 and 2000 have yielded images of this source at milliarcsecond angular
resolution. A central core is detected, with bright compact hot spots and
extended lobes on both sides. Model-fitting and other analysis of the data
(brightness profile, difference map) clearly indicate that the source is
expanding. We estimate the velocity of this expansion to be (0.085 +/- 0.016)
mas/yr, i.e. (0.33 +/- 0.06) c in both hot spots. Assuming a constant expansion
velocity, we estimate the kinematic age of the source at 550 yrs. We also study
the spectral index using VLBA observations at 1.3 GHz and MERLIN at 22 GHz. The
derived spectral age is 3000-5000 years in equipartition conditions. The two
estimates are discussed and found to be in agreement, given present
uncertainties.


title:
An Ultra-High-Resolution Survey of the Interstellar ^7Li-to-^6Li Isotope
  Ratio in the Solar Neighborhood

abstract:
  In an effort to probe the extent of variations in the interstellar ^7Li/^6Li
ratio seen previously, ultra-high-resolution (R ~ 360,000), high
signal-to-noise spectra of stars in the Perseus OB2 and Scorpius OB2
Associations were obtained. These measurements confirm our earlier findings of
an interstellar ^7Li/^6Li ratio of about 2 toward o Per, the value predicted
from models of Galactic cosmic ray spallation reactions. Observations of other
nearby stars yield limits consistent with the isotopic ratio ~ 12 seen in
carbonaceous chondrite meteorites. If this ratio originally represented the gas
toward o Per, then to decrease the original isotope ratio to its current value
an order of magnitude increase in the Li abundance is expected, but is not
seen. The elemental K/Li ratio is not unusual, although Li and K are formed via
different nucleosynthetic pathways. Several proposals to account for the low
^7Li/^6Li ratio were considered, but none seems satisfactory.
  Analysis of the Li and K abundances from our survey highlighted two sight
lines where depletion effects are prevalent. There is evidence for enhanced
depletion toward X Per, since both abundances are lower by a factor of 4 when
compared to other sight lines. Moreover, a smaller Li/H abundance is observed
toward 20 Aql, but the K/H abundance is normal, suggesting enhanced Li
depletion (relative to K) in this direction. Our results suggest that the
^7Li/^6Li ratio has not changed significantly during the last 4.5 billion years
and that a ratio ~ 12 represents most gas in the solar neighborhood. In
addition, there appears to be a constant stellar contribution of ^7Li,
indicating that one or two processes dominate its production in the Galaxy.


title:
Dirac's AEther in Curved Spacetime-II: The Geometric Amplification of
  the Cosmic Magnetic Induction

abstract:
  We search for an amplification mechanism of the seed cosmic magnetic
induction by studying a new version of the Dirac's aether in a curved
cosmological background. We find that an amplification takes place if the scale
factor R(t) varies with the cosmic time, which brings to the magnetic field the
effect of a geometric amplification.


title: The formation of the Seyfert continuum

abstract:
  We discuss recent results on the Seyfert spectral variability. Their observed
high energy variability is generally consistent with X-ray spectral slop
fluctuations produced by change of the soft photon luminosity in the sense that
spectra soften when the UV flux increases. These behaviors strongly favor a
thermal origin for the X-ray emission in these objects. We present the case of
NGC 7469, showing the results of the reanalysis of the simultaneous IUE/XTE
observations of this object using a realistic thermal Comptonization model to
fit the continuum instead of the simple power law approximation adopted in the
past.


title:
Ultradeep Near-Infrared ISAAC Observations of the HDF-S: Observations,
  Reduction, Multicolor Catalog, and Photometric Redshifts

abstract:
  We present deep near-infrared (NIR) Js, H, and Ks-band ISAAC imaging of the
WFPC2 field of the HDF-S. The 2.5'x 2.5' high Galactic latitude field was
observed with the VLT under the best seeing conditions with integration times
amounting to 33.6 hours in Js, 32.3 hours in H, and 35.6 hours in Ks. We reach
total AB magnitudes for point sources of 26.8, 26.2, and 26.2 respectively (3
sigma), which make it the deepest ground-based NIR observations to date, and
the deepest Ks-band data in any field. The effective seeing of the coadded
images is ~0.45" in Js, ~0.48" in H, and ~0.46" in Ks. Using published WFPC2
optical data, we constructed a Ks-limited multicolor catalog containing 833
sources down to Ks,tot ~< 26 (AB), of which 624 have seven-band optical-to-NIR
photometry. These data allow us to select normal galaxies from their rest-frame
optical properties to high redshift (z ~< 4). The observations, data reduction
and properties of the final images are discussed, and we address the detection
and photometry procedures that were used in making the catalog. In addition, we
present deep number counts, color distributions and photometric redshifts of
the HDF-S galaxies. We find that our faint Ks-band number counts are flatter
than published counts in other deep fields, which might reflect cosmic
variations or different analysis techniques. Compared to the HDF-N, we find
many galaxies with very red V-H colors at photometric redshifts 1.95 < z < 3.5.
These galaxies are bright in Ks with infrared colors redder than Js-Ks > 2.3
(in Johnson magnitudes). Because they are extremely faint in the observed
optical, they would be missed by ultraviolet-optical selection techniques, such
as the U-dropout method.


title:
Energy release due to antineutrino untrapping and diquark condensation
  in hot quark star evolution

abstract:
  We study the consequences of antineutrino trapping in hot quark matter for
quark star configurations with possible diquark condensation. Due to the
conditions of charge neutrality and beta-equilibrium the flavor asymmetry
increases with the number density of trapped antineutrinos such that above a
critical value of the antineutrino chemical potential of 30 MeV diquark
condensation is inhibited. When the quark star cools a two-phase structure
occurs: a superconducting quark matter core surrounded by a shell of normal
quark matter. Below the critical temperature of about 1 MeV, the antineutrino
mean free path becomes larger than the thickness of the normal quark matter
shell so that they get untrapped within a sudden process. By comparing the
masses of configurations with the same baryon number we estimate that the
release of energy due to the antineutrino untrapping transition can be in the
range of 10^{51} to 10^{52} erg.


title: Neutral Hydrogen in Galaxy Groups

abstract:
  We present preliminary results from a study of the neutral hydrogen (HI)
properties of an X-ray selected sample of nearby loose galaxy groups. This
forms part of a multi-wavelength investigation (X-ray, optical and radio) of
the formation and evolution of galaxies within a group environment. Some
initial findings of an ATNF Parkes Multibeam wide-area neutral hydrogen imaging
survey of 17 nearby galaxy groups include two new, potentially isolated clouds
of HI in the NGC 1052 and NGC 5044 groups and significant amounts of HI within
the group virial radii of groups NGC 3557 and IC 1459 - two groups with complex
X-ray structures that suggest they may still be in the act of virialisation.
Here we present ATCA high-resolution synthesis-imaging follow-up observations
of the distribution and kinematics of HI in these four groups.


title:
Classification of ISO SWS 01 spectra of proto-planetary nebulae: a
  search for precursors of planetary nebulae with [WR] central stars

abstract:
  We have analyzed ISO SWS 01 observations for 61 proto-planetary nebulae
candidates and classified their spectra according to their dominant chemistry.
On the basis of our classification and the more general classification of SWS
01 spectra by Kraemer et al. (2002) we discuss the connection between
proto-planetary nebulae candidates and planetary nebulae, with emphasis on
possible precursors of planetary nebulae with [WR] central stars.


title:
Optical and Near-Infrared Spectroscopy of a High-Redshift, Hard X-ray
  Emitting Spiral Galaxy

abstract:
  We present optical and near-infrared Keck spectroscopy of CXOHDFN
J123635.6+621424 (hereafter HDFX28), a hard X-ray source at a redshift of z =
2.011 in the flanking fields of the Hubble Deep Field-North (HDF-N). HDFX28 is
a red source (R - K_s = 4.74) with extended steep-spectrum (alpha > 0.87)
microjansky radio emission and significant emission (441 microJy) at 15
microns. Accordingly, initial investigations prompted the interpretation that
HDFX28 is powered by star formation. Subsequent Chandra imaging, however,
revealed hard (Gamma = 0.30) X-ray emission indicative of absorbed AGN
activity, implying that HDFX28 is an obscured, Type II AGN. The optical and
near-infrared spectra presented herein corroborate this result; the
near-infrared emission lines cannot be powered by star formation alone, and the
optical emission lines indicate a buried AGN. HDFX28 is identified with a
face-on, moderately late-type spiral galaxy. Multi-wavelength morphological
studies of the HDF-N have heretofore revealed no galaxies with any kind of
recognizable spiral structure beyond z > 2. We present a quantitative analysis
of the morphology of HDFX28, and we find the measures of central concentration
and asymmetry to be indeed consistent with those expected for a rare
high-redshift spiral galaxy.


title: Dark energy effects on the Lyman-alpha forest

abstract:
  In quintessence models, the dark energy content of the universe is described
by a slowly rolling scalar field whose pressure and energy density obey an
equation of state of the form p=w $\rho$; w is in general a function of time
such that w<-1/3, in order to drive the observed acceleration of the Universe
today. The cosmological constant model LCDM corresponds to the limiting case
w=-1. In this paper, we explore the prospects of using the Lyman-alpha forest
to constrain w, using semi-analytical techniques to model the intergalactic
medium (IGM). A different value of w changes both the growth factor and the
Hubble parameter as a function of time. The resulting change in the optical
depth distribution affects the optical depth power spectrum, the number of
regions of high transmission per unit redshift and the cross-correlation
coefficient of spectra of quasar pairs. These can be detected in current data,
provided we have independent estimates of the thermal state of the IGM, its
ionization parameter and the baryon density.


title: The Evolution of the Global Stellar Mass Density at 0 < z < 3

abstract:
  The build-up of stellar mass in galaxies is the consequence of their past
star formation and merging histories. Here we report measurements of rest-frame
optical light and calculations of stellar mass at high redshift based on an
infrared-selected sample of galaxies from the Hubble Deep Field North. The
bright envelope of rest-frame B-band galaxy luminosities is similar from 0<z<3,
and the co-moving luminosity density is constant to within a factor of 3 over
that redshift range. However, galaxies at higher redshifts are bluer, and
stellar population modeling indicates that they had significantly lower
mass-to-light ratios than those of present-day L* galaxies. This leads to a
global stellar mass density, Omega_*(z), which rises with time from z=3 to the
present. This measurement essentially traces the integral of the cosmic star
formation history that has been the subject of previous investigations. 50-75%
of the present-day stellar mass density had formed by z ~ 1, but at z ~= 2.7 we
find only 3-14% of today's stars were present. This increase in Omega_* with
time is broadly consistent with observations of the evolving global star
formation rate once dust extinction is taken into account, but is steeper at
1<z<3 than predicted by some recent semi-analytic models of galaxy formation.
The observations appear to be inconsistent with scenarios in which the bulk of
stars in present-day galactic spheroids formed at z>>2.


title: Formation of Globular Clusters in Merging Galaxies

abstract:
  Collisions and mergers of gas-rich galaxies trigger bursts of star and
cluster formation. Of the thousands of clusters typically formed during a major
merger, only the most massive and compact survive for Gigayears as globular
clusters (GCs). In <~1 Gyr old merger remnants, these `second-generation' GCs
appear by the hundreds as young halo clusters of about solar metallicity. Their
likely descendants, metal-rich GCs of intermediate age (2 - 5 Gyr), have
recently been found in ~10 elliptical galaxies, where they appear as slightly
overluminous red GCs with a still power-law-like luminosity function. Their
color and radial distributions suggest that they evolve into the red metal-rich
GCs observed in old ellipticals. There is good evidence that second-generation
GCs form from giant molecular clouds shocked by the rapid pressure increase in
merger-induced starbursts. This mechanism supports the view that the universal
pressure increase during cosmological reionization may have triggered the
formation of the metal-poor globulars observed in galaxies of all types.


title: Temperature Variations from HST Spectroscopy of the Orion Nebula

abstract:
  We present HST/STIS long-slit spectroscopy of NGC 1976. Our goal is to
measure the intrinsic line ratio [O III] 4364/5008 and thereby evaluate the
electron temperature (T_e) and the fractional mean-square T_e variation (t_A^2)
across the nebula. We also measure the intrinsic line ratio [N II] 5756/6585 in
order to estimate T_e and t_A^2 in the N^+ region. The interpretation of the [N
II] data is not as clear cut as the [O III] data because of a higher
sensitivity to knowledge of the electron density as well as a possible
contribution to the [N II] 5756 emission by recombination (and cascading). We
present results from binning the data along the various slits into tiles that
are 0.5" square (matching the slit width). The average [O III] temperature for
our four HST/STIS slits varies from 7678 K to 8358 K; t_A^2 varies from 0.00682
to at most 0.0176. For our preferred solution, the average [N II] temperature
for each of the four slits varies from 9133 K to 10232 K; t_A^2 varies from
0.00584 to 0.0175. The measurements of T_e reported here are an average along
each line of sight. Therefore, despite finding remarkably low t_A^2, we cannot
rule out significantly larger temperature fluctuations along the line of sight.
The result that the average [N II] T_e exceeds the average [O III] T_e confirms
what has been previously found for Orion and what is expected on theoretical
grounds. Observations of the proplyd P159-350 indicate: large local extinction
associated; ionization stratification consistent with external ionization by
theta^1 Ori C; and indirectly, evidence of high electron density.


title:
Implicit gauge symmetry emerging in the N-body problem of celestial
  mechanics

abstract:
  We revisit the Lagrange and Delaunay systems of equations for the orbital
elements, and point out a previously neglected aspect of these equations: in
both cases the orbit resides on a certain 9-dimensional submanifold of the
12-dimensional space spanned by the orbital elements and their time
derivatives. We demonstrate that there exists a vast freedom in choosing this
submanifold. This freedom of choice (=freedom of gauge fixing) reveals a
symmetry hiding behind Lagrange's and Delaunay's systems, which is,
mathematically, analogous to the gauge invariance in electrodynamics. Just like
a convenient choice of gauge simplifies calculations in electrodynamics, so the
freedom of choice of the submanifold may, potentially, be used to create
simpler schemes of orbit integration. On the other hand, the presence of this
feature may be a previously unrecognised source of numerical instability.

categories: astro-ph math-ph math.MP nlin.CD physics.class-ph physics.hist-ph


title: The Outer Edges of Dwarf Irregular Galaxies: Stars and Gas

abstract:
  We have in recent years come to view dwarf galaxy evolution in the broader
context of the cosmic evolution of large-scale structure. Dwarf galaxies, as
the putative building blocks of hierarchical galaxy formation, and also as the
most numerous galaxies in the Universe, play a central role in cosmic
evolution. In particular, the interplay of galactic and intergalactic material
around dwarf irregulars must be more extensive than in more massive disk
galaxies because of their lower gravitational potential and lower interstellar
pressures. The outer regions of dwarf irregular galaxies therefore yield vital
clues to the dominant processes in this interaction zone.
  The Workshop addressed a number of questions related to the role of the outer
regions in the evolution of dwarf galaxies and broader consequences. On-line
Workshop Proceedings are at http://www.lowell.edu/Workshops/Lowell02/


title: SiO Observations of the NGC 1333 IRAS 2A Protostellar Jet

abstract:
  We present 86.8 GHz SiO J=2-1 observations of the molecular outflow from the
protostellar source NGC 1333 IRAS 2A. Silicon monoxide is a sensitive tracer of
shocks in molecular gas, and the emission clearly traces terminal bowshocks at
the ends of the outflow lobes, as well as emission knots and a source
coincident with the protostar. Our three-field mosaic from the BIMA
interferometer covers the entire outflow length, including both lobes. The most
prominent emission feature, the eastern bowshock, shows SiO at the leading
edge, clearly displaced from the maximum seen in CO. This is in contrast to
recent observations by Chandler & Richer (2001) of the HH 211 jet, where SiO
traced primarily internal working surfaces and was less extended than the CO.
Our results are consistent with prompt entrainment at the leading edge of the
IRAS 2A bowshocks.


title: Observational constraints on the curvaton model of inflation

abstract:
  Simple curvaton models can generate a mixture of of correlated primordial
adiabatic and isocurvature perturbations. The baryon and cold dark matter
isocurvature modes differ only by an observationally null mode in which the two
perturbations almost exactly compensate, and therefore have proportional
effects at linear order. We discuss the CMB anisotropy in general mixed models,
and give a simple approximate analytic result for the large scale CMB
anisotropy. Working numerically we use the latest WMAP observations and a
variety of other data to constrain the curvaton model. We find that models with
an isocurvature contribution are not favored relative to simple purely
adiabatic models. However a significant primordial totally correlated baryon
isocurvature perturbation is not ruled out. Certain classes of curvaton model
are thereby ruled out, other classes predict enough non-Gaussianity to be
detectable by the Planck satellite. In the appendices we review the relevant
equations in the covariant formulation and give series solutions for the
radiation dominated era.


title: Gravitational Tunneling Radiation

abstract:
  The isolated black hole radiation of both Hawking and Zel'dovich are
idealized abstractions as there is always another body to distort the
potential. This is considered with respect to both gravitational tunneling, and
black hole "no-hair" theorems. The effects of a second body are to lower the
gravitational barrier of a black hole and to give the barrier a finite rather
than infinite width so tha a particle can escape by tunneling (as in field
emission) or over the top of the lowered barrier (as in Schottky emission).
Thus radiation may be emitted from black holes in a process differing from that
of Hawking radiation, P SH, which has been undetected for over 24 years. The
radiated power from a black hole derived here is PR e ^2__ PSH, where e ^2__ is
he ransmission probability for radiation through the barrier. This is similar
to electric field emission of electrons from a metal in that the emission can
in principle be modulated and beamed. The temperature and entropy of black
holes are reexamined. Miniscule black holes herein may help explain the missing
mass of the universe, accelerated expansion of the universe, and anomalous
rotation of spiral galaxies. A gravitational interference effect for black hole
radiation similar to the Aharonov-Bohm effect is also examined.


title:
All Sky Doppler Extrasolar Planet Surveys with a Multi-object Dispersed
  Fixed-delay Interferometer

abstract:
  We propose to use a high throughput and high precision multi-object dispersed
fixed-delay interferometer for all sky Doppler surveys for extrasolar planets.
  This instrument, a combination of a fixed-delay interferometer with a
moderate resolution spectrometer,is completely different from current echelle
spectrometers. Doppler RV is measured through monitoring interference fringe
shifts of stellar absorption lines over a broad band. Coupling this
multi-object instrument with a wide field telescope (a few degree, such as
Sloan and WIYN) and UV, visible and near-IR detectors will allow to
simultaneously obtain hundreds of stellar fringing spectra for searching for
planets. The RV survey speed can be increased by more than 2 orders of
magnitude over that for the echelles.
  A prototype dispersed fixed-delay interferometer has been observed at the
Hobby-Eberly 9m and Palomar 5m telescopes in 2001 and demonstrated photo noise
limited Doppler precision with Aldebaran. Our recent observations at the KPNO
2.1m telescope in 2002 demonstrate a short term Doppler precision of ~ 3 m/s
with eta Cas (V = 3.5), a RV stable star and also obtained a RV curve for 51
Peg. (V = 5.5), confirming previous planet detection with an independent RV
technique. The total measured detection efficiency including the sky, telescope
and fiber transmission losses, the instrument and iodine transmission losses
and detector quantum efficiency is 3.4% under 1.5 arcsec seeing conditions,
which is comparable to all of the echelle spectrometers for planet detection.


title: Little Black Holes:Dark Matter And Ball Lightning

abstract:
  Small,quiescent black holes can be considered as candidates for the missing
dark matter of the universe,and as the core energy source of ball lightning.By
means of gravitational tunneling,directed radiation is emitted from black holes
in a process much attenuated from that of Hawking radiation,P SH, which has
proven elusive to detect.Gravitational tunneling emission is similar to
electric field emission of electronsfrom a metal in that a second body is
involved which lowers the barrier and gives the barrier a finite rather than
infinite width.Hawking deals with a single isolated black hole.


title: Wide field CCD photometry of the globular cluster M92

abstract:
  We present wide field CCD photometry of a galactic globular cluster M92
obtained in the V and I bands with the CFH12K mosaic CCD at the
Canada-France-Hawaii Telescope. A well-defined color-magnitude diagram is
derived down to 5 magnitudes fainter than the cluster main sequence turn-off.
After removing the background contribution, we obtain luminosity and mass
functions, surface density profiles, and the surface number density maps of the
stars belonging to the cluster. The surface density profile of all stars shows
that the cluster's halo extends at least out to ~30' from the cluster center in
agreement with previous study, but the profile of faint stars at the very outer
region of the cluster shows a different gradient compared with that of bright
stars. For a mass function of the cluster, we find that the inner region of the
cluster has x = 1.2+-0.2, whereas the outer region has x = 1.8 +-0.3, clearly
indicating a mass segregation of the cluster. An estimate of the photometric
mass of the cluster implies that the remnant populations (white dwarfs and
neutron stars) contribute at least 25% of the total cluster mass. The surface
density map of M92 shows some evidence that the tidal tail of M92 may be
oriented perpendicular to the direction toward the Galactic center.


title:
The Cosmic-Ray Proton and Helium Spectra measured with the CAPRICE98
  balloon experiment

abstract:
  A new measurement of the primary cosmic-ray proton and helium fluxes from 3
to 350 GeV was carried out by the balloon-borne CAPRICE experiment in 1998.
This experimental setup combines different detector techniques and has
excellent particle discrimination capabilities allowing clear particle
identification. Our experiment has the capability to determine accurately
detector selection efficiencies and systematic errors associated with them.
Furthermore, it can check for the first time the energy determined by the
magnet spectrometer by using the Cherenkov angle measured by the RICH detector
well above 20 GeV/n. The analysis of the primary proton and helium components
is described here and the results are compared with other recent measurements
using other magnet spectrometers. The observed energy spectra at the top of the
atmosphere can be represented by (1.27+-0.09)x10^4 E^(-2.75+-0.02) particles
(m^2 GeV sr s)^-1, where E is the kinetic energy, for protons between 20 and
350 GeV and (4.8+-0.8)x10^2 E^(-2.67+-0.06) particles (m^2 GeV nucleon^-1 sr
s)^-1, where E is the kinetic energy per nucleon, for helium nuclei between 15
and 150 GeV nucleon^-1.


title: Jets at all scales

abstract:
  I discuss recent developments in the field of relativistic jets in AGNs.
After a brief review of our current knowledge of emission from Blazars, I
discuss some consequences of the recent detection made by {\it Chandra} of
X-ray emission from extended jets. Finally I report some recent results on the
problem of the connection between accretion and jets, study that in principle
could shed light on the important issue of jet formation.


title:
Proper Motions and CCD-photometry of Stars in the Region of the Open
  Cluster NGC 1513

abstract:
  The results of astrometric and photometric investigations of the poorly
studied open cluster NGC 1513 are presented. The proper motions of 353 stars
with the root-mean-square error of 1.9 mas/yr were obtained by means of the
automated measuring complex "Fantasy" scanning of 8 astrometric plates covering
the time interval of 101 years. A total of 141 astrometric cluster members have
been identified. BV CCD-photometry was made for the stars in a square size 17
arcmin x 17 arcmin centered on cluster. 33 stars with the high reliability were
considered to be cluster members by two criteria. The estimation of NGC 1513
age is 2.54 E+08 years. Tables 2 and 3 are only available in electronic form at
the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/.


title: Performance characteristics of a parallel treecode

abstract:
  I describe here the performances of a parallel treecode with individual
particle timesteps. The code is based on the Barnes-Hut algorithm and runs
cosmological N-body simulations on parallel machines with a distributed memory
architecture using the MPI message passing library. For a configuration with a
constant number of particles per processor the scalability of the code has been
tested up to P=32 processors. The average CPU time per processor necessary for
solving the gravitational interactions is within $\sim 10 %$ of that expected
from the ideal scaling relation. The load balancing efficiency is high
($\simgt90%$) if the processor domains are determined every large timestep
according to a weighting scheme which takes into account the total particle
computational load within the timestep.


title: Introducing GOLDMine: A new Galaxy Database on the WEB

abstract:
  The new World Wide Web site "GOLDMine" (Galaxy On Line Database Milano
Network) (http://goldmine.mib.infn.it) contains a multiwavelength data-base of
an optically selected sample of 3267 galaxies in the Virgo cluster and in the
Coma Supercluster. It is designed for professional astronomers who wish to find
data and images for these galaxies.
  Data, gathered in 15 years of observational campaigns by the authors or taken
from the literature include general parameters (catalogue names, celestial
coordinates, morphological type, recessional velocity etc.); multiwavelength
continuum photometry (total UV, U, B, V, J, H, K, FIR and radio magnitudes/flux
densities); line photometry (HI, H_2, H_alpha); dynamical parameters
(rotational velocity from the HI and H_alpha lines, velocity dispersion) and
structural parameters (light concentration index, effective radius and
brightness, asymptotic magnitude) in the optical (B and V) and Near Infrared (H
or K) bands. Images include finding charts, optical (B and V), H_alpha, Near
Infrared (H and/or K) and true color RGB frames (when available). Radial light
profiles obtained from the B, V, H or K band images are also available.
Integrated optical spectra along with broad Spectral Energy Distributions (SED)
from the UV to the radio domain are given. All images can be obtained in JPG
format, but the original (reduced) FITS images can be downloaded as well. The
database will be updated regularly and will be extended to other local clusters
and superclusters. Astronomers who wish to have their images included in
GOLDMine are strongly encouraged to send us their material.


title: New Nitrogen and Carbon in AF-supergiants

abstract:
  The AF-supergiants in the Galaxy and the SMC allow us to examine predictions
from evolution models through their CNO abundances. In these proceedings, we
recalculate the NLTE nitrogen abundances in 22 Galactic and 9 SMC A-supergiants
using improved atomic data and model atmospheres to compare with new evolution
models. The new abundances are higher than previously published values, and
suggest that most of these stars have undergone substantial mixing with
CN-cycled gas. While there is no clear relationship with mass, there is an
apparent relation with metallicity since the SMC stars (including B-stars) have
larger nitrogen enrichments. We suggest that rotational mixing is indicated
from the main-sequence throughout the supergiant range, with more substantial
rotational mixing in the SMC stars. In addition, the SMC AF-supergiants appear
to have undergone the first dredge-up during a previous red giant phase, and
possibly the Galactic AF-supergiants have as well. All abundances are compared
to the new solar abundances from M. Asplund (this conference).


title:
A First Close Look at the Balmer-edge Behavior of the Quasar Big Blue
  Bump

abstract:
  We have found for the first time a Balmer edge feature in the Big Blue Bump
emission of a quasar. The feature is seen in the polarized flux spectrum of the
quasar, where all the emissions from outside the nucleus are scraped off and
removed. The existence of the Balmer-edge absorption feature directly indicates
that the Big Blue Bump is indeed thermal and optically-thick.


title: The effects of spiral arms on the multi-phase ISM

abstract:
  Statistical parameters of the ISM driven by thermal energy injections from
supernova explosions have been obtained from 3D, nonlinear,
magnetohydrodynamic, shearing-box simulations for spiral arm and interarm
regions. The density scale height obtained for the interarm regions is 50%
larger than within the spiral arms because of the higher gas temperature. The
filling factor of the hot gas is also significantly larger between the arms and
depends sensitively on magnetic field strength.


title:
Evolution of AGB stars at varying surface C/O ratio: The crucial effect
  of molecular opacities

abstract:
  This study calls attention to the importance of properly coupling the
molecular opacities to the actual surface abundances of TP-AGB stars that
experience the third dredge-up and/or hot-bottom burning, i.e. with surface
abundances of carbon and oxygen varying with time. New TP-AGB calculations with
variable opacities -- replacing the usually adopted solar-scaled opacity tables
-- have proven to reproduce, for the first time, basic observables of carbon
stars, like their effective temperatures, C/O ratios, and near-infrared
colours. Moreover, it turns out that the effect of envelope cooling -- due to
the increase in molecular opacities -- may cause other important effects,
namely: i) shortening of the C-star phase; ii) possible reduction or shut-down
of the third dredge-up in low-mass carbon stars; and iii) weakening or even
extinction of hot-bottom burning in intermediate-mass stars.


title:
Ho Measurement from VLT Deep I-band Surface Brightness Fluctuations in
  NGC 564 and NGC 7619

abstract:
  We have measured the Hubble constant Ho in NGC 564 at cz ~ 5800 km/s and in
NGC 7619 at cz ~ 3700 km/s with deep I-band Surface Brightness Fluctuation
distance measurements at the ESO Very Large Telescope (VLT). We obtain Ho = 70
+/- 7 +/- 6 km/s/Mpc for NGC 564 and Ho = 68 +/- 6 +/- 6 km/s/Mpc for NGC 7619.
The actual SBF sample used for the measurement of Ho in the Hubble Space
Telescope Key Project on the Extragalactic Distance Scale (Freedman et al.
2001) amounts to six galaxies. When we combine the measurements from this work
with our previous VLT I-band SBF distance measurement in IC 4296 (Mei et al.
2000), we obtain : Ho = 68 +/- 5 +/- 6 km/s/Mpc. When we add the Freedman et
al. (2001) SBF sample, we obtain Ho = 71 +/- 4 +/- 6 km/s/Mpc.


title: CNO Abundances in Dwarf and Spiral Galaxies

abstract:
  CNO abundances in galaxies bear on issues of galactic evolution as well as
stellar evolution and nucleosynthesis. Knowledge about them in dwarf and spiral
galaxies depends mainly on emission lines from H II regions, with information
from stars and supernova remnants available for galaxies in the Local Group.
  Oxygen abundances can be related to both local and global properties of the
parent galaxies such as gas fraction, surface brightness, galaxy luminosity,
rotation speed and morphological type, and in H II regions they range from
1/30th solar (using the new calibration) to slightly above solar. C/O is a more
or less smoothly increasing function of O/H, flat at low metallicities and
rising above 12+log(O/H) = 8.0 with a 45 degree slope. N/O behaves quite
similarly in the traditional `primary followed by secondary' style, but with a
substantial scatter at least around O-abundance 8.0. C/N ratios show no clear
trend with metallicity.


title:
The Curvaton Hypothesis and the eta-problem of Quintessential Inflation,
  with and without Branes

abstract:
  It is argued why, contrary to expectations, steep brane-inflation cannot
really help in overcoming the eta-problem of quintessential inflation
model-building. In contrast it is shown that the problem is substantially
ameliorated under the curvaton hypothesis. This is quantified by considering
possible modular quintessential inflationary models in the context of both
standard and brane cosmology.


title: Dust properties of the dark cloud IC5146 - Submillimeter and NIR imaging

abstract:
  We present the results of a submillimeter dust continuum study of a molecular
ridge in IC5146 carried out at 850micron and 450micron with SCUBA on the James
Clerk Maxwell Telescope (JCMT). The mapped region is 14'x2.5' in size (2pc x
0.3pc) and consists of at least four dense cores which are likely to be
prestellar in nature. To study the dust properties of the ridge and its
embedded cores, we combined the dust emission data with dust extinction data
obtained by Lada et al. (1999) from the NIR colors of background giant stars.
The ridge shows dust extinctions above ~10mag, rising up to 35mag in the cores.
  A map of dust temperatures, constructed from the continuum flux ratios, shows
significant temperature gradients: we find temperatures of up to ~20K in the
outskirts and between the cores, and down to ~10K in the cores themselves. The
cores themselves are almost isothermal. We used the extinction data to derive
in addition a map of the dust emissivity. Its average value agrees well with
the canonical value of Mathis (1990). We find that the dust emissivity
parametrized by kappa_850/kappa_V increases by a factor of about 4 when the
dust temperature decreases from ~20K to ~12K. A Monte Carlo simulation shows
that this change is significant with regard to the estimated calibration
uncertainties. This is consistent with models of dust evolution in prestellar
cores by Ossenkopf & Henning (1994) and with the previous detection of
gas-phase depletion of CO in one of the IC5146 cores by Kramer et al. 1999.


title: Mapping the 3-D Dark Matter potential with weak shear

abstract:
  We investigate the practical implementation of Taylor's (2002) 3-dimensional
gravitational potential reconstruction method using weak gravitational lensing,
together with the requisite reconstruction of the lensing potential. This
methodology calculates the 3-D gravitational potential given a knowledge of
shear estimates and redshifts for a set of galaxies. We analytically estimate
the noise expected in the reconstructed gravitational field, taking into
account the uncertainties associated with a finite survey, photometric redshift
uncertainty, redshift-space distortions, and multiple scattering events. In
order to implement this approach for future data analysis, we simulate the
lensing distortion fields due to various mass distributions. We create
catalogues of galaxies sampling this distortion in three dimensions, with
realistic spatial distribution and intrinsic ellipticity for both ground-based
and space-based surveys. Using the resulting catalogues of galaxy position and
shear, we demonstrate that it is possible to reconstruct the lensing and
gravitational potentials with our method. For example, we demonstrate that a
typical ground-based shear survey with redshift limit z=1 and photometric
redshifts with error Delta z=0.05 is directly able to measure the 3-D
gravitational potential for mass concentrations >10^14 M_\odot between
0.1<z<0.5, and can statistically measure the potential at much lower mass
limits. The intrinsic ellipticity of objects is found to be a serious source of
noise for the gravitational potential, which can be overcome by Wiener
filtering or examining the potential statistically over many fields. We examine
the use of the 3-D lensing potential to measure mass and position of clusters
in 3-D, and to detect clusters behind clusters.


title:
Toward Ultra Short Gamma Ray Burst Ground Based Detection, SGARFACE
  status

abstract:
  We present the status and motivation of the Short GAmma Ray Front Air
Cherenkov Experiment (SGARFACE) which will be operated parallel to standard
Very High Energy gamma-ray observations using the Whipple 10m telescope.
SGARFACE is sensitive to 100MeV-10GeV gamma-ray bursts with durations ranging
from 100ns to 100us providing a fluence sensitivity as low as few $\rm 1E-9
erg/cm^2. Preliminary data taking started in November 2002.


title:
A simplified model of the formation of structures in the dark matter,
  and a background of very long gravitational waves

abstract:
  Collapse of the rotating spheroid is approximated by a system of ordinary
differential equations describing its dynamics. The gravitational potential is
approximated by the one of the iniform Maclaurin spheroid.
  Developement of gravitational instability and collapse in the dark matter
medium do not lead to any shock formation or radiation, but is characterized by
non-collisional relaxation, which is accompanied by the mass and angular
momentum losses. Phenomenological account of these processes is done in this
model. Formation of the equilibrium configuration dynamics of collapse is
investigated for several parameters, characterizing the configuration. A very
long gravitational wave emission during the collapse is estimated, and their
possible connection with the observed gravitational lenses is discussed.


title: Recent Results from the VERITAS Collaboration

abstract:
  A decade after the discovery of TeV gamma-rays from the blazar Mrk 421 (Punch
et al. 1992), the list of TeV blazars has increased to five BL Lac objects: Mrk
421 (Punch et al. 1992; Petry et al. 1996; Piron et al. 2001), Mrk 501 (Quinn
et al. 1996; Aharonian et al. 1999; Djannati-Atai et al. 1999), 1ES2344+514
(Catanese et al. 1998), H1426+428 (Horan et al. 2000, 2002; Aharonian et al.
2002; Djannati-Atai et al. 2002) and 1ES1959+650 (Nishiyama et al. 1999;
Konopelko et al. 2002; Holder et al. 2002). In this paper we report results
from recent observations of Mrk 421, H1426+428 and 1ES1959+650 using the
Whipple Observatory 10 m telescope.


title: The Final Parsec Problem

abstract:
  The coalescence of massive black hole binaries is one of the main sources of
low-frequency gravitational radiation that can be detected by LISA. When two
galaxies containing massive black holes merge, a binary forms at the center of
the new galaxy. We discuss the evolution of the binary after its separation
decreases below one parsec. Whether or not stellar dynamical processes can
drive the black holes to coalesce depends on the supply of stars that scatter
against the binary. We discuss various mechanisms by which this supply can be
replenished after the loss cone has been depleted.


title:
CO (J=7->6) Observations of NGC 253: Cosmic Ray Heated Warm Molecular
  Gas

abstract:
  We report observations of the CO J=7->6 transition toward the starburst
nucleus of NGC 253. This is the highest-excitation CO measurement in this
source to date, and allows an estimate of the molecular gas excitation
conditions. Comparison of the CO line intensities with a large velocity
gradient, escape probability model indicates that the bulk of the 2-5 x 10^7
solar masses of molecular gas in the central 180 pc is highly excited. A model
with T ~ 120 K, n_H_2 ~ 4.5 x 10^4 cm^-3 is consistent with the observed CO
intensities as well as the rotational H2 lines observed with ISO.
  The inferred mass of warm, dense molecular gas is 10--30 times the atomic gas
mass as traced through its [CII] and [OI] line emission. This large mass ratio
is inconsistent with photodissociation region models where the gas is heated by
far-UV starlight. It is also not likely that the gas is heated by shocks in
outflows or cloud-cloud collisions. We conclude that the best mechanism for
heating the gas is cosmic rays, which provide a natural means of uniformly
heating the full volume of molecular clouds. With the tremendous supernova rate
in the nucleus of NGC 253, the CR heating rate is at least ~800 times greater
than in the Galaxy, more than sufficient to match the cooling observed in the
CO lines.


title:
Young stars at large distances from the galactic plane: mechanisms of
  formation

abstract:
  We have collected from the literature a list of early-type stars, situated at
large distances from the galactic plane, for which evidence of youth seems
convincing. We discuss two possible formation mechanisms for these stars:
ejection from the plane by dynamical interactions within small clusters, and
formation away from the plane, via induced shocks created by spiral density
waves. We identify the stars that could be explained by each mechanism. We
conclude that the ejection mechanism can account for about two thirds of the
stars, while a combination of star formation at z = 500-800 pc from the plane
and ejection, can account for 90 percent of these stars. Neither mechanism, nor
both together, can explain the most extreme examples.


title:
II. Accurate Positions and Proper Motions of Stellar SiO Masers near the
  Galactic Center

abstract:
  Menten, Reid, Eckart and Genzel (1997) accurately determined the position of
Sgr A* on an infrared image, by aligning the infrared image with positions
measured for SiO masers, associated with infrared-bright evolved stars, at
radio wavelengths. We now report greatly improved radio positions and, for the
first time, proper motions of many stellar SiO masers at the Galactic Center.
These positions and motions, coupled with better infrared imaging, allow a much
improved location of Sgr A* on infrared images. With current data, infrared
stars can be placed in a reference frame tied to Sgr A*, to an accuracy of
approximately 10 mas in position and 1 mas/yr in motion. The position of Sgr A*
is, within uncertainties, consistent with stellar accelerations and the
measured orbital focus of the star S2. The star S2 was observed within 16 mas
(130 AU in projection) of Sgr A* on 2002 May 02. Finally, we find that the
central stellar cluster moves with Sgr A* to within approximatly 70 km/s.


title: CDM Substructure in Gravitational Lenses: Tests and Results

abstract:
  We use a simple statistical test to show that the anomalous flux ratios
observed in gravitational lenses are created by gravitational perturbations
from substructure rather than propagation effects in the interstellar medium or
incomplete models for the gravitational potential of the lens galaxy. We review
current estimates that the substructure represents between 0.6% and 7% (90%
confidence) of the lens galaxy mass, and outline future observational programs
which can improve the results.


title: Dark Group: Dark Energy and Dark Matter

abstract:
  We study the possibility that a dark group, a gauge group with particles
interacting with the standard model particles only via gravity, is responsible
for containing the dark energy and dark matter required by present day
observations. We show that it is indeed possible and we determine the
constrains for the dark group.
  The non-perturbative effects generated by a strong gauge coupling constant
can de determined and a inverse power law scalar potential IPL for the dark
meson fields is generated parameterizing the dark energy. On the other hand it
is the massive particles, e.g. dark baryons, of the dark gauge group that give
the corresponding dark matter. The mass of the dark particles is of the order
of the condensation scale $\Lambda_c$ and the temperature is smaller then the
photon's temperature. The dark matter is of the warm matter type. The only
parameters of the model are the number of particles of the dark group. The
allowed values of the different parameters are severely restricted. The dark
group energy density at $\Lambda_c$ must be $ \Omdgc \leq 0.17$ and the
evolution and acceptable values of dark matter and dark energy leads to a
constrain of $\Lmc$ and the IPL parameter $n$ giving $\Lambda_c=O(1-10^3) eV$
and $0.28 \leq n \leq 1.04$.


title:
Cosmological Constraints from a Combined Analysis of the Cluster Mass
  Function and Microwave Background Anisotropies

abstract:
  We present constraints on several cosmological parameters from a combined
analysis of the most recent Cosmic Microwave Background anisotropy data and the
Sloan Digital Sky Survey cluster mass function. We find that the combination of
the two data sets breaks several degeneracies among the parameters and provides
the following constraints: $\sigma_8=0.76\pm0.09$,
$\Omega_m=0.26^{+0.06}_{-0.07}$, $h=0.66^{+0.05}_{-0.06}$, $n=0.96 \pm 0.05$,
$\tau_c=0.07^{+0.07}_{-0.05}$.


title: High Latitude Dust and the 617 MHz - 850 \mu m relation in NGC 5775

abstract:
  We present continuum observations of the edge-on spiral galaxy NGC 5775 at
617 MHz with the Giant Metrewave Radio Telescope (GMRT) and at 850 \mu m with
the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk
Maxwell Telescope (JCMT). We report the detection of dust at high-latitudes,
extending to about 5 kpc from the disk of the galaxy, and spurs of non-thermal
radio emission. The 617 MHz and 850 \mu m distributions are compared with one
another and we find a strong correlation between metre wavelength radio
emission and sub-mm emission in the disk and at high-latitudes. This suggests
that there may be a more fundamental relationship between cold dust and
synchrotron radiation other than the link via star formation.


title: Dynamical Black Hole Growth and the M_{BH}-\sigma Relation

abstract:
  This poster discusses a possible explanation for the relationship between the
mass of the central supermassive black hole and the velocity dispersion in the
bulge of the host galaxy. We suppose that the black hole and the dark matter
halo are forming simultaneously as matter falls in, and a self-similar system
then exists in which the mass and the velocities of the system evolve as
power-law functions of time. This leads naturally to a relationship between the
black hole mass and the velocities in the halo which, with a reasonable choice
of cosmological parameters, is in good agreement with the observed
relationship. We also confirm this relationship with more robust numerical
results.


title:
Space Velocities of Southern Globular Clusters. IV. First Results for
  Inner-Galaxy Clusters

abstract:
  We have measured the absolute proper motions of four low-latitude,
inner-Galaxy globular clusters. These clusters are: NGC 6266 (M62), NGC 6304,
NGC 6316 and NGC 6723. The proper motions are on the Hipparcos system, as no
background extragalactic objects are found in these high-extinction regions.
The proper-motion uncertainties range between 0.3 and 0.6 mas/yr.
  We discuss the kinematics of these clusters and of three additional bulge
clusters -- NGC 6522, NGC 6528 and NFC 6553 -- whose proper motions with
respect to bulge stars had been determined previously. We find that all of the
clusters have velocities that confine them to the bulge region. Of the three
metal poor clusters ([Fe/H] < -1.0), NGC 6522, and NGC 6723 have kinematics
consistent with halo membership. The third cluster, NGC 6266 however, appears
to belong to a rotationally-supported system. Of the four metal rich clusters
([Fe/H] >= -1.0), NGC 6304 and NGC 6553 also have kinematics consistent with
membership to a rotationally-supported system. NGC 6528 has kinematics,
metallicity and mass that argue in favor of a genuine Milky-Way bar cluster.
NGC 6316's kinematics indicate membership to a hotter system than the bar.


title: Cosmology With Interacting Dark Energy

abstract:
  The early cosmic inflation, when taken along with the recent observations
that the universe is currently dominated by a low density vacuum energy, leads
to at least two potential problems which modern cosmology must address. First,
there is the old cosmological constant problem, with a new twist: the
coincidence problem. Secondly, cosmology still lacks a model to predict the
observed current cosmic acceleration and to determine whether or not there is a
future exit out of this state (as previously in the inflationary case). This
constitutes (what is called here) a dynamical problem. In this article a
framework is proposed to address these two problems, based on treating the
cosmic background vacuum (dark) energy as both dynamical and interacting. The
universe behaves as a vacuum-driven cosmic engine which, in search of
equilibrium, always back-reacts to vacuum-induced accelerations by increasing
its inertia (internal energy) through vacuum energy dissipation. The process
couples cosmic vacuum (dark) energy to matter to produce future-directed
increasingly comparable amplitudes in these fields by setting up oscillations
in the decaying vacuum energy density and corresponding sympathetic ones in the
matter fields. By putting bounds on the relative magnitudes of these coupled
oscillations the model offers a natural and conceptually simple channel to
discuss the coincidence problem, while also suggesting a way to deal with the
dynamical problem. A result with useful observational implications is an
equation of state w(t) which specifically predicts a variable, quasi-periodic,
acceleration for the current universe. This result can be directly tested by
future observational techniques such as SNAP.


title: The New Cosmology: Mid-term Report Card for Inflation

abstract:
  Inflation has been the driving idea in cosmology for two decades and is a
pillar of the New Cosmology. The inflationary paradigm has now passed its first
round of significant tests, with two of its three basics predictions confirmed
at about the 10% level. The Inflationary Paradigm has some of the truth. Over
the next decade the precision of these tests, most of which involve
measurements of CMB anisotropy and polarization, will improve 30 fold or
more(!), testing inflation more sharply and possibly elucidating the underlying
cause. Especially important in this regard is detecting the inflation-produced
gravitational waves, either directly or through their CMB polarization
signature. While inflation has by no means been verified, its successes have
raised the bar for competitor theories: Any alternative must feature the two
hallmarks of inflation: superluminal expansion and entropy production.


title:
Simulations of Galaxy Formation in a Lambda CDM Universe II: The Fine
  Structure of Simulated Galactic Disks

abstract:
  We present a detailed analysis of the dynamical properties of a simulated
disk galaxy assembled hierarchically in the Lambda CDM cosmogony. At z=0, two
distinct dynamical components are identified on the basis of the orbital
parameters of stars in the galaxy: a slowly rotating, centrally concentrated
spheroid and a disk-like component largely supported by rotation. These
components are also recognized in the surface brightness profile of the galaxy,
which can be very well approximated by the superposition of an R^{1/4} spheroid
and an exponential disk. However, neither does the dynamically-identified
spheroid follow de Vaucouleurs' law nor is the disk purely exponential, a
resultwhich calls for caution when estimating the importance of the disk from
traditional photometric decomposition techniques. The disk may be further
decomposed into a thin, dynamically cold component with stars on nearly
circularorbits and a hotter, thicker component with orbital parameters
transitional between the thin disk and the spheroid. The spheroid is old, and
has essentiallyno stars younger than the time elapsed since the last major
accretion event ~8 Gyr ago. The majority of thin disk stars, form after the
merging activity is over, although a significant fraction ~15% of thin-disk
stars are old enough to predate the last major merger event. This unexpected
population of old disk stars consists mainly of the tidal debris of satellites
whose orbital plane was coincident with the disk and whose orbits were
circularized by dynamical friction prior to full disruption. Our results
highlight the role of satellite accretion events in shaping the disk and the
spheroidal component and reveal some of the clues to the assembly process of a
galaxy preserved in the detailed dynamics of old stellar populations.


title: Mass Limits to Primordial Star Formation from Protostellar Feedback

abstract:
  How massive were the first stars? This question is of fundamental importance
for galaxy formation and cosmic reionization. Here we consider how protostellar
feedback can limit the mass of a forming star. For this we must understand the
rate at which primordial protostars accrete, how they and their feedback output
evolve, and how this feedback interacts with the infalling matter. We describe
the accretion rate with an ``isentropic accretion'' model: the rate is
initially very large (~0.03 M_sun/yr when m_* =1 M_sun) and declines as
m_*^{-3/7}. Protostellar evolution is treated with a model that tracks the
total energy of the star. A key difference compared to previous studies is
allowance for rotation of the infalling envelope. This leads to photospheric
conditions at the star and dramatic differences in the feedback. Two feedback
mechanisms are considered: HII region breakout and radiation pressure from
Lyman-alpha and FUV photons. Radiation pressure appears to be the dominant
mechanism for suppressing infall, becoming dynamically important around 20
M_sun.


title:
Mass-temperature relation of galaxy clusters: implications from the
  observed luminosity-temperature relation and X-ray temperature function

abstract:
  We derive constraints on the mass-temperature relation of galaxy clusters
from their observed luminosity-temperature relation and X-ray temperature
function. Adopting the isothermal gas in hydrostatic equilibrium embedded in
the universal density profile of dark matter halos, we compute the X-ray
luminosity for clusters as a function of their hosting halo mass. We find that
in order to reproduce the two observational statistics, the mass-temperature
relation is very tightly constrained as T_{gas} = (1.5~2.0)keV
(M_{vir}/10^{14}h_{70}^{-1}M_\odot)^{0.5~0.55}, and a simple self-similar
evolution model (T_{gas} \propto M_{vir}^{2/3}) is strongly disfavored. In the
cosmological model that we assume (a \Lambda CDM universe with \Omega_0=0.3,
\lambda_0=0.7 and h_{70}=1), the derived mass-temperature relation suggests
that the mass fluctuation amplitude \sigma_8 is 0.7--0.8.


title: A tentative elementary model of quasars

abstract:
  A very simple model of quasar and Seyfert galaxy is obtained using the
"Coherent Raman Effect on time-Incoherent Light" (CREIL) to explain a part of
the observed redshifts. As its redshift is mostly provided by the CREIL, a QSO
is not very far, its kernel may be a neutron star fed by the accretion of a
disk, fed itself by the fall of many satellites. Disk and satellites are slowed
by a relatively dense halo. The electric charges resulting of the friction of
the disk produce flat lightnings, thus radio noise emitted mostly perpendicular
to the disk, and X rays. The optical spectrum, including the shape of the
spectral lines is explained without uncommon physics such as dark matter, by a
splitting of the very wide lines resulting from simultaneous absorption and
frequency shift, splitting due to a modulation of the redshift resulting from
variations of a magnetic field.


title: The Missing Link in Star Cluster Evolution

abstract:
  The currently most popular models for the dynamical evolution of star
clusters predict that the power-law Cluster Luminosity Functions (CLFs) of
young star cluster systems will be transformed rapidly into the universal
Gaussian CLFs of old Milky Way-type "globular" cluster systems. Here, we
provide the first evidence for a turn-over in the intermediate-age,
approximately 1 Gyr-old CLF in the center of the nearby starburst galaxy M82,
which very closely matches the universal CLFs of old Milky Way-type globular
cluster systems. This provides an important test of both cluster disruption
theories and hierarchical galaxy formation models. It also lends strong support
to the scenario that these young cluster systems may eventually evolve into old
Milky Way-type globular cluster systems. M82's proximity, its shortest known
cluster disruption time-scale of any galaxy, and its well-defined peak of
cluster formation make it an ideal candidate to probe the evolution of its star
cluster system to fainter luminosities, and thus lower masses, than has been
possible for any galaxy before.


title:
Constraining the Cosmological Density of Compact Objects with the
  Long-Term Variability of Quasars

abstract:
  By comparing the results from numerical microlensing simulations to the
observed long-term variability of quasars, strong upper limits on the
cosmological density of compact objects in the 0.0001-1 solar mass range may in
principle be imposed. Here, this method is generalized from the Einstein-de
Sitter universe to the currently favored Omega_M=0.3, Omega_Lambda=0.7
cosmology and applied to the latest observational samples. We show that the use
of high-redshift quasars from variability-selected samples has the potential to
substantially improve current constraints on compact objects in this mass
range. We also investigate to what extent the upper limits on such hypothetical
dark matter populations are affected by assumptions concerning the size of the
optical continuum-emitting region of quasars and the velocity dispersion of
compact objects. We find that mainly due to uncertainties in the typical value
of the source size, cosmologically significant populations of compact objects
cannot safely be ruled out with this method at the present time.


title: The Role of Magnetic Fields in Spiral Galaxies

abstract:
  Interstellar magnetic fields are strong: up to 25 muG in spiral arms and 40
muG in nuclear regions. In the spiral galaxy NGC 6946 the average magnetic
energy density exceeds that of the thermal gas. Magnetic fields control the
evolution of dense clouds and possibly the global star formation efficiency in
galaxies. Gas flows and shocks in spiral arms and bars are modified by magnetic
fields. Magnetic forces in star-forming circumnuclear regions are able to drive
mass inflow towards the active nucleus. Magnetic fields are essential for the
propagation of cosmic rays and the formation of galactic winds and halos.


title: High Resolution Observations of the CMB Power Spectrum with ACBAR

abstract:
  We report the first measurements of anisotropy in the cosmic microwave
background (CMB) radiation with the Arcminute Cosmology Bolometer Array
Receiver (ACBAR). The instrument was installed on the 2.1m Viper telescope at
the South Pole in January 2001; the data presented here are the product of
observations up to and including July 2002. The two deep fields presented here,
have had offsets removed by subtracting lead and trail observations and cover
approximately 24 deg^2 of sky selected for low dust contrast. These results
represent the highest signal to noise observations of CMB anisotropy to date;
in the deepest 150GHz band map, we reached an RMS of 8.0\mu K per 5' beam. The
3 degree extent of the maps, and small beamsize of the experiment allow the
measurement of the CMB anisotropy power spectrum over the range \ell = 150-3000
with resolution of \Delta \ell=150. The contributions of galactic dust and
radio sources to the observed anisotropy are negligible and are removed in the
analysis. The resulting power spectrum is found to be consistent with the
primary anisotropy expected in a concordance \Lambda CDM Universe.