title: Short-term emission line and continuum variations in Mrk110

abstract:
  We present results of a variability campaign of Mrk110 performed with the
9.2-m Hobby-Eberly Telescope (HET) at McDonald Observatory. The high S/N
spectra cover most of the optical range. They were taken from 1999 November
through 2000 May. The average interval between the observations was 7.3 days
and the median interval was only 3.0 days. Mrk110 is a narrow-line Seyfert 1
galaxy. During our campaign the continuum flux was in a historically low stage.
Considering the delays of the emission lines with respect to the continuum
variations we could verify an ionization stratification of the BLR. We derived
virial masses of the central black hole from the radial distances of the
different emission lines and from their widths. The calculated central masses
agree within 20%. Furthermore, we identified optical HeI singlet emission lines
emitted in the broad-line region. The observed line fluxes agree with
theoretical predictions. We show that a broad wing on the red side of the
[OIII]5007 line is caused by the HeI singlet line at 5016A.


title: Chemical Enrichment and Energetics of the ICM with Redshift

abstract:
  In this paper we show preliminary results concerning the chemical and
energetic enrichment of the ICM by means of supernova-driven wind models in
elliptical galaxies. These models are obtained by taking into account new
prescriptions about supernova remnant evolution in the interstellar medium. We
find that models, which can reproduce the Fe abundance and the [$\alpha$/Fe]
ratios observed in the ICM, predict that the SN energy input can provide about
0.3 keV per ICM particle. We have obtained this result by assuming that each SN
explosion inject on the average into the ISM no more than 20% of its initial
blast wave energy. The predicted energy per particle is not enough to break the
cluster self-similarity but is more than predicted in previous models.


title:
Early type stars at high galactic latitudes I. Ten young massive B-type
  stars

abstract:
  We present the results of quantitative spectral analyses of ten apparently
normal B-type stars. These stars were found to be young massive B-type stars at
distances of z=2.6 to 7.6 kpc from the galactic plane based on their positions
in the (Teff, log g) diagram, normal abundance patterns and/or large projected
rotational velocities. We discuss formation scenarios (runaway star scenarios
versus a scenario for star formation in the halo) by comparing times-of-flight
and evolutionary time scales. For all stars (except SB 357 and HS 1914+7139)
both the scales are similar, indicating that the stars could have formed in the
galactic disk and been ejected from there soon aftertheir birth. Derived
ejection velocities range from 130 km/s to 440 km/s and may be used to
constrain models for ejection mechanisms. Using new proper motion measurements
we show that PHL 346, which was considered the most likely candidate for a
young B-type star born in the halo, can be explained as a runaway star from the
galactic plane.


title: Far-Infrared ISO Limits on Dust Disks around Millisecond Pulsars

abstract:
  We report 60 and 90 micron observations of 7 millisecond pulsars with the
ISOPHOT instrument and describe our analysis procedures. No pulsars were
detected, and typical (3\sigma) upper limits are 150 mJy. We combine our
results with others in the literature and use them to place constraints on the
existence of protoplanetary or dust disks around millisecond pulsars.


title: Jeans' gravitational instability and nonextensive kinetic theory

abstract:
  The concept of Jeans gravitational instability is rediscussed in the
framework of nonextensive statistics and its associated kinetic theory. A
simple analytical formula generalizing the Jeans criterion is derived by
assuming that the unperturbed self- gravitating collisionless gas is
kinetically described by the $q$-parameterized class of power law velocity
distributions. It is found that the critical values of wavelength and mass
depend explicitly on the nonextensive $q$-parameter. The standard Jeans
wavelength derived for a Maxwellian distribution is recovered in the limiting
case $q$=1. For power-law distributions with cutoff, the instability condition
is weakened with the system becoming unstable even for wavelengths of the
disturbance smaller than the standard Jeans length $\lambda_J$.


title:
Early type stars at high galactic latitudes II. Four evolved B-type
  stars of unusual chemical composition

abstract:
  We present the result of differential spectral analyses of a further four
apparently normal B-type stars. Abundance anomalies (e.g. He, C, N enrichment),
slow rotation and/or high gravities suggest that the programme stars are
evolved low-mass B-type stars. In order to trace their evolutionary status
several scenarios are discussed. Post-AGB evolution can be ruled out. PG
0229+064 and PG 1400+389 could be horizontal branch (HB) stars, while HD 76431
and SB 939 have already evolved away from the extreme HB (EHB). The low helium
abundance of HD 76431 is consistent with post-EHB evolution. The enrichment in
helium, carbon and nitrogen of the remaining stars can be explained either by
deep mixing of nuclearly processed material to the surface or by diffusion
processes modified by magnetic fields and/or stellar winds. A kinematic study
of their galactic orbits indicates that the stars belong to an old disk
population.


title:
Image and Non-Image Parameters of Atmospheric Cherenkov Events: a
  comparative study of their gamma-ray/hadron classification potential in UHE
  regime

abstract:
  In this exploratory simulation study, we compare the event-progenitor
classification potential of a variety of measurable parameters of atmospheric
Cherenkov pulses which are produced by ultra-high energy (UHE) gamma-ray and
hadron progenitors and are likely to be recorded by the TACTIC array of
atmospheric Cherenkov telescopes. The parameters derived from Cherenkov images
include Hillas, fractal and wavelet moments, while those obtained from
non-image Cherenkov data consist of pulse profile rise-time and base width and
the relative ultraviolet to visible light content of the Cherenkov event. It is
shown by a neural-net approach that these parameters, when used in suitable
combinations, can bring about a proper segregation of the two event types, even
with modest sized data samples of progenitor particles.


title: Kinematics and dynamics of the "superthin" edge-on disk galaxy IC 5249

abstract:
  We present spectroscopic observations of the stellar motions in the disk of
the superthin edge-on spiral galaxy IC 5249 and re-analyse synthesis
observations of the HI. We find that the HI rotation curve rises initially to
about 90-100 km/s, but contrary to the conclusion of Abe et al. (1999) flattens
well before the edge of the optical disk. Over most part of the optical disk we
have been able to establish that the (tangential) stellar velocity dispersion
is 25-30 km/s. From earlier surface photometry we adopt a value for the radial
scalelength of the disk of 7 +/- 1 kpc, a vertical scaleheight of 0.65 +/- 0.05
kpc and a disk truncation radius of 17 +/- 1 kpc. The very thin appearance of
IC 5249 on the sky is the result of a combination of a low (face-on) surface
brightness, a long scalelength and a a sharp truncation at only about 2.5
scalelengths. From various arguments we derive the stellar velocity dispersions
at a position one radial scalelength as sigma_R about 35 km/s, sigma_{theta}
about 30 km/s and sigma_z about 20 km/s. This is comparable to the values for
the disk of our Galaxy in the solar neighborhood.


title: Variation of Muon Counts Versus Solar Time

abstract:
  Project GRAND observes small variations in the number of incident muons when
plotted versus local solar time. The total accumulated number of muons by GRAND
over four years' time is ~140 billion. The data obtained by Project GRAND are
compared with data from neutron monitor stations at Climax and at Newark which
detect secondary neutrons. Project GRAND is an array of 64 proportional wire
chamber stations which are sensitive to secondary muons at energies greater
than 0.1 GeV. The mean energy of cosmic ray primaries which produce these muons
depends on the spectral index. For a differential spectral index of 2.4, the
most probable gamma ray primary energy is about 10 GeV, the response falling
steeply below this energy and slowly above this energy; this most probably
energy varies only slowly with spectral index.


title:
Multiwavelength Studies of PSR J1420-6048, a Young Pulsar in the
  Kookaburra

abstract:
  We present X-ray, radio, and infrared observations of the 68 ms pulsar PSR
J1420-6048 and its surrounding nebula, a possible counterpart of the gamma-ray
source GeV J1417-6100/3EG J1420-6038. Pulsed X-ray emission at the radio period
is marginally detected by ASCA from a source embedded in the hard spectrum
X-ray nebula AX J1420.1-6049. At radio wavelengths, the pulsar is found to be
strongly linearly and circularly polarized, and the polarization sweep is
measured. A comparison of high resolution ATCA radio imaging of the
Kookaburra's upper wing (G313.6+0.3), which contains the pulsar and the X-ray
nebula, with infrared images suggests the radio emission is partly non-thermal.


title: Structure and dynamics of disks in galaxies

abstract:
  One the most cited papers in astronomy is Ken Freeman's 1970 paper on
exponential disks in galaxies. In this contribution I review what has been done
in this area since then and what we can infer about systematic properties of
disks in galaxies from surface photometry, HI synthesis observations and
measurements of stellar kinematics. Most disks have radial truncations at $3.6
\pm 0.6$ radial scalelengths $h\subr{R}$. Galaxy disk thicknesses
$h\subr{R}/h\subr{z}= 7.3 \pm 2.2$ imply that these disk cannot be ``maximum
disks''. I briefly discuss a recent study of the ``superthin'' edge-on galaxy
IC 5249.


title: A Project GRAND Study of the GLE of July 14, 2000

abstract:
  The Ground-Level Event (GLE) associated with the X5.7 solar flare of July 14,
2000 is studied by the Project GRAND proportional wire chamber array. Results
are compared to those obtained by the Climax Neutron Monitor experiment which
detects secondary neutrons. The Climax monitor, located in Climax, Colorado, is
operated by the University of Chicago. The time of the GLE signal of the Climax
station is examined for a possible coincident signal in the data of Project
GRAND. Project GRAND is an array of 64 proportional wire chamber stations. The
stations are sensitive to secondary muons with energies greater than 0.1 GeV.
The mean energy of primaries which produce these ground level muons depends on
the spectral index of the primary spectrum. For a differential spectral index
of 2.4, the most probable primary energy is 10 GeV falling rapidly below this
energy and falling slowly above this energy.


title: The Photophysics of the Carrier of Extended Red Emission

abstract:
  Interstellar dust contains a component which reveals its presence by emitting
a broad, unstructured band of light in the 540 to 950 nm wavelength range,
referred to as Extended Red Emission (ERE). The presence of interstellar dust
and ultraviolet photons are two necessary conditions for ERE to occur. This is
the basis for suggestions which attribute ERE to an interstellar dust component
capable of photoluminescence. In this study, we have collected all published
ERE observations with absolute-calibrated spectra for interstellar
environments, where the density of ultraviolet photons can be estimated
reliably. In each case, we determined the band-integrated ERE intensity, the
wavelength of peak emission in the ERE band, and the efficiency with which
absorbed ultraviolet photons are contributing to the ERE. The data show that
radiation is not only driving the ERE, as expected for a photoluminescence
process, but is modifying the ERE carrier as manifested by a systematic
increase in the ERE band's peak wavelength and a general decrease in the photon
conversion efficiency with increasing densities of the prevailing exciting
radiation. The overall spectral characteristics of the ERE and the observed
high quantum efficiency of the ERE process are currently best matched by the
recently proposed silicon nanoparticle (SNP) model. Using the experimentally
established fact that ionization of semiconductor nanoparticles quenches their
photoluminescence, we proceeded to test the SNP model by developing a
quantitative model for the excitation and ionization equilibrium of SNPs under
interstellar conditions for a wide range of radiation field densities.


title:
A reconstruction of the initial conditions of the Universe by optimal
  mass transportation

abstract:
  Reconstructing the density fluctuations in the early Universe that evolved
into the distribution of galaxies we see today is a challenge of modern
cosmology [ref.]. An accurate reconstruction would allow us to test
cosmological models by simulating the evolution starting from the reconstructed
state and comparing it to the observations. Several reconstruction techniques
have been proposed [8 refs.], but they all suffer from lack of uniqueness
because the velocities of galaxies are usually not known. Here we show that
reconstruction can be reduced to a well-determined problem of optimisation, and
present a specific algorithm that provides excellent agreement when tested
against data from N-body simulations. By applying our algorithm to the new
redshift surveys now under way [ref.], we will be able to recover reliably the
properties of the primeval fluctuation field of the local Universe and to
determine accurately the peculiar velocities (deviations from the Hubble
expansion) and the true positions of many more galaxies than is feasible by any
other method.
  A version of the paper with higher-quality figures is available at
http://www.obs-nice.fr/etc7/nature.pdf


title:
A general, three-dimensional fluid dynamics code for stars in binary
  systems

abstract:
  We describe the theory and implementation of a three-dimensional fluid
dynamics code which we have developed for calculating the surface geometry and
circulation currents in the secondaries of interacting binary systems. The main
method is based on an Eulerian-Lagrangian scheme to solve the advective and
force terms in Euler's equation. Surface normalised spherical polar coordinates
are used to allow the accurate modelling of the surface of the star, as is
necessary when free surfaces and irradiation effects are to be considered. The
potential and its gradient are expressed as sums of Legendre polynomials, which
allows a very efficient solution of Poisson's equation. The basic solution
scheme, based on operator splitting, is outlined, and standard numerical tests
are presented.


title: Detection of Cosmic Shear from STIS Parallel Archive Data: Data Analysis

abstract:
  In June 1997, parallel observations using the Space Telescope Imaging
Spectrograph (STIS) on the HST started to be taken in substantial numbers along
many different lines-of-sight. We are using the imaging data to investigate the
distortion of background galaxies by the gravitational field of the large scale
matter distribution, also known as Cosmic Shear. This poster presents the data
and the catalog production that leads to the cosmic shear result presented in
the poster "First Cosmic Shear results from STIS parallel program archive data"
(Haemmerle et al., this conference). The data is publicly available also at
http://www.stecf.org/projects/shear .


title: The Evolution of Disks and Winds in Dwarf Novae Outbursts

abstract:
  Far ultraviolet (FUV) observations are excellent probes of the inner
accretion disk, disk outflows, and the mass-accumulating white dwarf in
cataclysmic variables. Here we study the contrasting behavior of two canonical
dwarf novae in outburst by presenting FUSE FUV (904 -- 1187 A) spectroscopy of
U Gem and SS Cyg. We observed each system four times during a single outburst.
The outburst peak and early decline spectra of SS Cyg are well fit by models of
a steady-state accretion disk and a biconical wind. A broad, blueshifted OVI
wind-formed absorption line is the only strong spectral feature. In late
outburst decline, OVI and CIII lines are seen as broad emission features and
the continuum has flattened. In U Gem, the continua of the optical outburst
plateau spectra are plausibly fit by accretion disk model spectra. The spectra
also show numerous narrow, low-velocity absorption lines that do not originate
in the inner accretion disk. We discuss the line spectra in the context of
partial absorption of the FUV continuum by low-velocity, vertically-extended
material located at large disk radii. The late outburst decline spectrum of U
Gem is dominated by the white dwarf. WD model fits confirm the sub-solar C and
super-solar N abundances found in earlier studies.


title: Spectral Components of SS 433

abstract:
  We present results from new optical and UV spectroscopy of the unusual binary
system SS 433, and we discuss the relationship of the particular spectral
components we observe to the properties of the binary. (1) The continuum
spectrum which we associate with flux from the super-Eddington accretion disk
and the dense part of its wind. (2) H-alpha moving components which are formed
far from the binary orbital plane in the relativistic jets. (3) H-alpha and He
I "stationary" emission lines which we suggest are formed in the disk wind in a
volume larger than the dimensions of the binary. (4) A weak "stationary"
emission feature we identify as a C II 7231,7236 blend that attains maximum
radial velocity at the orbital quadrature of disk recession. (5) Absorption and
emission features from outflowing clumps in the disk wind (seen most clearly in
an episode of blue-shifted Na I emission). (6) We found no clear evidence of
the absorption line spectrum of the optical star, although we point out the
presence of He I absorption features (blended with the stationary emission)
with the expected radial velocity trend at the orbital and precessional phases
when the star might best be seen. (7) A rich interstellar absorption spectrum
of diffuse interstellar bands. The results suggest that the binary is embedded
in an expanding thick disk (detected in recent radio observations) which is fed
by the wind from the super-Eddington accretion disk.


title: A Chandra X-ray Study of Cygnus A - III. The Cluster of Galaxies

abstract:
  The results from a recent Chandra ACIS-S study of the cluster surrounding
Cygnus A are presented. We have deprojected the X-ray spectra taken from
various elliptical shells in order to derive the run of temperature, density,
pressure, and abundance for the ICM as a function of radius. We confirm a drop
in temperature of the X-ray emitting gas from $\sim 8$ keV more than $\sim
2^{\prime}$ from the center to $\simeq 5$ keV some $30^{\prime\prime}$ from the
center, with the coolest gas immediately adjacent to the radio galaxy.
``Belts'' of slightly cooler ($\simeq 4$ keV) X-ray emitting gas run around the
minor dimension of the cavity created by the radio source. We find a
metallicity gradient in the X-ray emitting gas, with the highest metallicities
($\sim$ solar) in the inner annuli, decreasing to $\sim 0.3$ solar in the outer
parts. The total mass within 500 kpc is found to be (2.0--2.8) $\times 10^{14}
M_{\odot}$ and approximately 3.5--5% of the mass is X-ray emitting gas
[ABRIDGED].


title: Status of Project GRAND's Proportional Wire Chamber Array

abstract:
  Project GRAND is an extensive air shower array of proportional wire chambers.
It has 64 stations in a 100m x 100m area; each station has eight planes of
proportional wire chambers with a 50 mm steel absorber plate above the bottom
two planes. This arrangement of planes, each 1.25 square meters of area, allow
an angular measurement for each track to 0.25 degrees in each of two
projections. The steel absorber plate allows a measurement of the identity of
each muon track to 96% accuracy. Two data-taking triggers allow data to be
simultaneously taken for a) extensive air showers (multiple coincidence station
hits) at about 1 Hz and b) single muons (single tracks of identified muons) at
2000 Hz. Eight on-line computers pre-analyze the single track data and store
the results on magnetic tape in compacted form with a minimum of computer
dead-time. One additional computer reads data from the shower triggers and
records this raw data on a separate magnetic tape with no pre-analysis.


title: A Measurement of Secondary Muon Angular Distributions

abstract:
  Project GRAND is an array of proportional wire chambers composed of 64
stations with each station containing eight proportional wire planes and a 50
mm steel plate. The proportional wire planes together with the steel absorber
allow a measurement of the angle and identity of single muon tracks. Of the two
data-taking triggers, one is for single tracks. Since the rate of single muon
tracks at sea level above the muon energy threshold of the experiment (0.1 GeV)
is substantial, good statistics are available by accumulating several years of
data. A map in sidereal right ascension and declination is obtained as well as
one in a sun-centered coordinate system in order to study the sidereal and
solar effects separately.


title: No planet for HD 166435

abstract:
  The G0V star HD166435 has been observed by the fiber-fed spectrograph ELODIE
as one of the targets in the large extra-solar planet survey that we are
conducting at the Observatory of Haute-Provence. We detected coherent,
low-amplitude, radial-velocity variations with a period of 3.7987days,
suggesting a possible close-in planetary companion. Subsequently, we initiated
a series of high-precision photometric observations to search for possible
planetary transits and an additional series of CaII H and K observations to
measure the level of surface magnetic activity and to look for possible
rotational modulation. Surprisingly, we found the star to be photometrically
variable and magnetically active. A detailed study of the phase stability of
the radial-velocity signal revealed that the radial-velocity variability
remains coherent only for durations of about 30days. Analysis of the time
variation of the spectroscopic line profiles using line bisectors revealed a
correlation between radial velocity and line-bisector orientation. All of these
observations, along with a one-quarter cycle phase shift between the
photometric and the radial-velocity variationss, are well explained by the
presence of dark photospheric spots on HD166435. We conclude that the
radial-velocity variations are not due to gravitational interaction with an
orbiting planet but, instead, originate from line-profile changes stemming from
star spots on the surface of the star. The quasi-coherence of the
radial-velocity signal over more than two years, which allowed a fair fit with
a binary model, makes the stability of this star unusual among other active
stars. It suggests a stable magnetic field orientation where spots are always
generated at about the same location on the surface of the star.


title: The Extended Shapes of Galactic Satellites

abstract:
  We are exploring the extended stellar distributions of Galactic satellite
galaxies and globular clusters. For seven objects studied thus far, the
observed profile departs from a King function at large r, revealing a ``break
population'' of stars. In our sample, the relative density of the ``break''
correlates to the inferred M/L of these objects. We discuss opposing hypotheses
for this trend: (1) Higher M/L objects harbor more extended dark matter halos
that support secondary, bound, stellar ``halos''. (2) The extended populations
around dwarf spheroidals (and some clusters) consist of unbound, extratidal
debris from their parent objects, which are undergoing various degrees of tidal
disruption. In this scenario, higher M/L ratios reflect higher degrees of
virial non-equilibrium in the parent objects, thus invalidating a precept
underlying the use of core radial velocities to obtain masses.


title:
Evidence for Jet Domination of the Nuclear Radio Emission in
  Low-luminosity Active Galactic Nuclei

abstract:
  We present simultaneous, sub-arcsecond (<=50pc) resolution 5 GHz, 8.4 GHz,
and 15 GHz VLA observations of a well-defined sample of sixteen low-luminosity
active galactic nuclei (LLAGNs). The radio emission in most of these nuclei
does not show the rising spectrum (0.2 <= s <= 1.3, L_nu propto nu^{s})
expected from thermal electrons in an advection dominated accretion flow (ADAF)
with or without weak to moderately-strong outflows. Rather, the flat radio
spectra are indicative of either synchrotron self-absorbed emission from jets,
convection-dominated accretion flows (CDAFs) with L >= 10^{-5} L_Edd, or ADAFs
with strong (p >= 0.6) outflows. The jet interpretation is favored by three
factors: a) the detection of pc-scale radio extensions, morphologically
reminiscent of jets, in the five nuclei with the highest peak radio
flux-density; b) the domination of parsec-scale jet radio emission over
unresolved `core' emission in the three best-studied nuclei; and c) the lack of
any clear correlation between radio spectral shape and black hole mass as would
be expected from the dependence of the radio turnover frequency on black hole
mass in ADAF and CDAF models. A jet domination of nuclear radio emission
implies significantly lower accretion rates in ADAF-type models than earlier
estimated from core radio luminosities.


title:
Galactic populations of radio and gamma-ray pulsars in the polar cap
  model

abstract:
  We simulate the characteristics of the Galactic population of radio and
$\gamma$-ray pulsars using Monte Carlo techniques. At birth, neutron stars are
spatially distributed in the Galactic disk, with supernova-kick velocities, and
randomly dispersed in age back to $10^9$ years. They are evolved in the
Galactic gravitational potential to the present time. From a radio luminosity
model, the radio flux is filtered through a selected set of radio-survey
parameters. $\gamma$-ray luminosities are assigned using the features of recent
polar cap acceleration models invoking space-charge-limited flow, and a pulsar
death valley further attenuates the population of radio-loud pulsars. Assuming
a simple emission geometry with aligned radio and $\gamma$-ray beams of 1
steradian solid angle, our model predicts that EGRET should have seen 7
radio-loud and 1 radio-quiet, $\gamma$-ray pulsars. With much improved
sensitivity, GLAST, on the other hand, is expected to observe 76 radio-loud and
74 radio-quiet, $\gamma$-ray pulsars of which 7 would be identified as pulsed
sources. We also explore the effect of magnetic field decay on the
characteristics of the radio and $\gamma$-ray pulsar populations. Including
magnetic field decay on a timescale of 5 Myr improves agreement with the radio
pulsar population and increases the predicted number of GLAST detected pulsars
to 90 radio-loud and 101 radio-quiet (9 pulsed) $\gamma$-ray pulsars. The lower
flux threshold allows GLAST to detect $\gamma$-ray pulsars at larger distances
than those observed by the radio surveys used in this study.


title: Variability of Active Galactic Nuclei

abstract:
  Continuum and emission-line variability of active galactic nuclei provides a
powerful probe of microarcsecond scale structures in the central regions of
these sources. In this contribution, we review basic concepts and methodologies
used in analyzing AGN variability. We develop from first principles the basics
of reverberation mapping, and pay special attention to emission-line transfer
functions. We discuss application of cross-correlation analysis to AGN light
curves. Finally, we provide a short review of recent important results in the
field.


title:
Far Ultraviolet Spectroscopic Explorer Observations of the Seyfert 1.5
  Galaxy NGC 5548 in a Low State

abstract:
  We present far-ultraviolet spectra of the Seyfert 1.5 galaxy NGC 5548
obtained in 2000 June with the Far Ultraviolet Spectroscopic Explorer (FUSE).
Our data span the observed wavelength range 915--1185 Angstroms at a resolution
of 20 km/s. The spectrum shows a weak continuum and emission from O VI, C III,
and He II. The FUSE data were obtained when the AGN was in a low state, which
has revealed strong, narrow O VI emission lines. We also resolve intrinsic,
associated absorption lines of O VI and the Lyman series. Several distinct
kinematic components are present, spanning a velocity range of 0 to -1300 km/s
relative to systemic, with kinematic structure similar to that seen in previous
observations of longer wavelength ultraviolet (UV) lines. We explore the
relationship between the far-UV absorbers and those seen previously in the UV
and X-rays. We find that the high-velocity UV absorption component is
consistent with being low-ionization, contrary to some previous claims, and is
consistent with its non-detection in high-resolution X-ray spectra. The
intermediate velocity absorbers, at -300 to -400 km/s, show H I and O VI column
densities consistent with having contributions from both a high-ionization
X-ray absorber and a low-ionization UV absorber. No single far-UV absorbing
component can be solely identified with the X-ray absorber.


title: Computational aspects of astrophysical MHD and turbulence

abstract:
  The advantages of high-order finite difference scheme for astrophysical MHD
and turbulence simulations are highlighted. A number of one-dimensional test
cases are presented ranging from various shock tests to Parker-type wind
solutions. Applications to magnetized accretion discs and their associated
outflows are discussed. Particular emphasis is placed on the possibility of
dynamo action in three-dimensional turbulent convection and shear flows, which
is relevant to stars and astrophysical discs. The generation of large scale
fields is discussed in terms of an inverse magnetic cascade and the
consequences imposed by magnetic helicity conservation are reviewed with
particular emphasis on the issue of alpha-quenching.


title: X-ray Properties of High Redshift Clusters

abstract:
  We describe the ensemble X-ray properties of high redshift clusters with
emphasis on changes with respect to the local population. Cluster X-ray
luminosity evolution is detected in five nearly independent surveys. The
relevant issue now is characterizing this evolution. Cluster temperature
evolution provides constraints on the dark matter and dark energy content of
the universe. These constraints are complementary to and in agreement with
those of the cosmic microwave background and supernovae, showing that the
present universe is dominated by a dark energy. X-ray images show that most z >
0.75 clusters are not relaxed, hinting that the cluster formation epoch is z ~
1.


title: Probing Dark Matter Substructure in Lens Galaxies

abstract:
  We investigate the effects of numerous dark matter subhalos in a galaxy-sized
halo on the events of strong lensing, to assess their presence as expected from
the cold dark matter scenario. Lens galaxies are represented by a smooth
ellipsoid in an external shear field and additional cold dark matter subhalos
taken from Monte Carlo realizations which accord with recent N-body results. We
also consider other possible perturbers, globular clusters and luminous dwarf
satellites, for comparison. We then apply the models to the particular lens
systems with four images, B1422+231 and PG1115+080, for which smooth lens
models are unable to reproduce both the positions of the images and their radio
flux ratios or dust-free optical flux ratios simultaneously. We show that the
perturbations by both globular clusters and dwarf satellites are too small to
change the flux ratios, whereas cold dark matter subhalos are most likely
perturbers to reproduce the observed flux ratios in a statistically significant
manner. This result suggests us the presence of numerous subhalos in lens
galaxies, which is consistent with the results of cosmological N-body
simulations.


title: The Optical Proper Motions of HH 7-11 and Cep E (HH 377)

abstract:
  A key ingredient in understanding the dynamics of stellar outflows is their
proper motion. We have used optical images in the [SII] emission at 6717/31 A
and the red Digitized Palomar Observatory Sky Survey (DSS) plates to determine
the proper motion of HH 7-11 system and the optical knot of Cep E (HH 377). The
DSS plate measurements span nearly 37 years for both HH 7-11 and HH 377 and
have wide field of view, which allows an accurate determination of the proper
motions despite their relatively low angular resolution. The optical images,
with higher angular resolution, cover a shorter period of 7 and 4 years,
respectively, and have been used to complement the DSS measurements. From the
DSS plates we have found that HH 377 has a proper motion of 0.031 +/- 0.003
arcsec/yr with a PA = 206 arcdeg, i.e. moving away from IRAS 230111+63, that at
a distance of 730 pc corresponds to a tangential velocity of 107 +/- 14 km/s.
The values obtained from the optical images are consistent with these
measurements. Similarly, the proper motions of HH 7-11 range from 0.015 +/-
0.009 (HH 9) to 0.044 +/- 0.007 (HH 11) arcsec/yr, and the flow is moving away
from SVS 13 with a mean PA = 136 arcdeg. At a distance of 330 pc, these motions
correspond to tangential velocities of 25 - 70 km/s, i.e. comparable to the
original values obtained by Herbig & Jones (1983). The measurements from the
optical CCD [SII] images are again consistent with these motions, although in
detail there are some difference, particularly for HH 7 and HH 10.


title:
Inhomogeneities in Newtonian Cosmology and its Backreaction to the
  Evolution of the Universe

abstract:
  We study an effect of inhomogeneity of density distribution of the Universe.
We propose a new Lagrangian perturbation theory with a backreaction effect by
inhomogeneity. The inhomogeneity affects the expansion rate in a local domain
and its own growing rate. We numerically analyze a one-dimensional
plane-symmetric model, and calculate the probability distribution functions
(PDFs) of several observed variables to discuss those statistical properties.
We find that the PDF of pairwise peculiar velocity shows an effective
difference from the conventional Lagrangian approach, i.e. even in
one-dimensional plane symmetric case, the PDF approaches an exponential form in
a small relative-velocity region, which agree with the N-body simulation.


title: Relativistic outflows from X-ray binaries (a.k.a. `Microquasars')

abstract:
  In this review I summarise the observational connections between accretion
and relativistic outflows -- jets -- in X-ray binaries. I argue that jets are
likely to be a fairly ubiquitous property of X-ray binaries as a whole, an
assertion which can be tested by further observations of the Atoll-type X-ray
binaries. I discuss broad patterns that are emerging from these observational
studies, such as a correlation between `hard' X-ray states and the presence of
radio emission, and the related anti-correlation between jet strength and
mass-accretion rate as inferred from X-ray studies alone. I briefly discuss
possible future directions for research and compare X-ray binary jets to those
from Active Galactic Nuclei and Gamma Ray Bursts.


title: Formation and pre-MS evolution of massive stars with growing accretion

abstract:
  We briefly describe the three existing scenarios for forming massive stars
and emphasize that the arguments often used to reject the accretion scenario
for massive stars are misleading. It is usually not accounted for the fact that
the turbulent pressure associated to large turbulent velocities in clouds
necessarily imply relatively high accretion rates for massive stars. We show
the basic difference between the formation of low and high mass stars based on
the values of the free fall time and of the Kelvin-Helmoltz timescale, and
define the concept of birthline for massive stars.
  Due to D-burning, the radius and location of the birthline in the HR diagram,
as well as the lifetimes are very sensitive to the accretion rate \dot M_accr.
If a form \dot M_accr=A (M/M_sun)^phi is adopted, the observations in the HR
diagram and the lifetimes support a value of A=10^{-5} M_sun/yr and a value of
phi>1. Remarkably, such a law is consistent with the relation found by
Churchwell (1998) and Henning et al. (2000) between the outflow rates and the
luminosities of ultra--compact HII regions, if we assume that a fraction 0.15
to 0.3 of the global inflow is accreted. The above relation implies high \dot
M_accr=10^{-3} M_sun/yr for the most massive stars. The physical possibility of
such high \dot M_accr is supported by current numerical models.
  Finally, we give simple analytical arguments in favour of the growth of \dot
M_accr with the already accreted mass. We also suggest that due to Bondi-Hoyle
accretion, the formation of binary stars is largely favoured among massive
stars in the accretion scenario.


title: Images of an equatorial outflow in SS433

abstract:
  We have imaged the X-ray binary SS433 with unprecedented Fourier-plane
coverage at 6cm using simultaneously the VLBA, MERLIN, and the VLA, and also at
20cm with the VLBA. At both wavelengths we have securely detected smooth,
low-surface brightness emission having the appearance of a `ruff' or collar
attached perpendicularly to the well-studied knotty jets in this system,
extending over at least a few hundred AU. We interpret this smooth emission as
a wind-like outflow from the binary, and discuss its implications for the
present evolutionary stage of this system.


title:
The Starburst-AGN connection: Implications for the Unification of
  Seyferts

abstract:
  Observations at ultraviolet, optical and near-infrared wavelengths have shown
the existence of recent star formation in the nuclear regions of Seyfert 2
(Sy2) galaxies that suggest a connection between the Starburst and the Seyfert
phenomenon. According with the standard unified models of AGN circumnuclear
starbursts also have to be present (and in the same numbers) in Sy1 as in Sy2
galaxies. This review discuss evidence in favor of the Starburst-AGN
connection, as well as possible differences in terms of star formation activity
between Sy1 and Sy2, that suggest an alternative interpretation of the Seyfert
classification to that proposed by the standard unification model.


title: Detection of a CMB decrement towards a cluster of mJy radiosources

abstract:
  We present the results of radio, optical and near-infrared observations of
the field of TOC J0233.3+3021, a cluster of milliJansky radiosources from the
TexOx Cluster survey. In an observation of this field with the Ryle Telescope
(RT) at 15 GHz, we measure a decrement in the cosmic microwave background (CMB)
of $-675 \pm 95 \mu$Jy on the RT's $\approx$ 0.65 k$\lambda$ baseline. Using
optical and infrared imaging with the McDonald 2.7-m Smith Reflector, Calar
Alto 3.5-m telescope and UKIRT, we identify the host galaxies of five of the
radiosources and measure magnitudes of $R \approx 24$, $J \approx 20$, $K
\approx 18$.
  The CMB decrement is consistent with the Sunyaev-Zel'dovich (SZ) effect of a
massive cluster of galaxies, which if modelled as a spherical King profile of
core radius $\theta_C = 20^{\prime\prime}$ has a central temperature decrement
of $900 \mu$K. The magnitudes and colours of the galaxies are consistent with
those of old ellipticals at $z \sim 1$. We therefore conclude that TOC
J0233.3+3021 is a massive, high redshift cluster. These observations add to the
growing evidence for a significant population of massive clusters at high
redshift, and demonstrate the effectiveness of combining searches for AGN
`signposts' to clusters with the redshift-independence of the SZ effect.


title:
Simultaneous single-pulse observations of radio pulsars: I. The
  polarization characteristics of PSR B0329+54

abstract:
  We present the first results from a programme of multi-frequency simultaneous
single pulse observations carried out as part of the European Pulsar Network.
We detail the main data analysis methods and apply them to simultaneous
observations of the strong pulsar B0329+54 at 1.4 and 2.7 GHz using the Jodrell
Bank and Effelsberg radio telescopes respectively. The pulses at different
frequencies are highly correlated in their total intensity, as seen in previous
experiments, and generally show consistent position angles of the linearly
polarized component. In contrast, the circularly polarized emission sometimes
shows clear differences between pulses received at different frequencies. These
results are unexpected and warrant further follow-up studies to interpret them
in the context of the intrinsic bandwidth of pulsar radiation.


title: Cosmic Shear from STIS Pure Parallels: Analysis

abstract:
  The measurement of cosmic shear requires deep imaging with high image quality
on many lines of sight to sample the statistics of large-scale structure. The
expected distortion of galaxy images by cosmic shear on the STIS angular scale
is a few percent, therefore the PSF anisotropy has to be understood and
controlled to an accuracy better than 1%. In this poster we present the
analysis of the PSF of STIS and a preliminary cosmic shear measurement using
archival data from the STIS pure parallel program to show that the STIS camera
on-board HST is well suited for our project. The data reduction and catalog
production are described in an accompanying paper (astro-ph/0102330).


title:
Iterative map-making methods for Cosmic Microwave Background data
  analysis

abstract:
  The map-making process of Cosmic Microwave Background data involves linear
inversion problems which cannot be performed by a brute force approach for the
large timelines of most modern experiments. We present optimal iterative
map-making methods, both COBE and Wiener, and apply these methods on simulated
data. They produce very well restored maps, by removing nearly completely the
correlated noise that appears as intense stripes on the simply pixel-averaged
maps.


title: Broad-line radio galaxies: old and feeble?

abstract:
  Far-infrared photometry of broad-line radio galaxies shows this class of AGN
to consist of many hot and some cool infrared emitters, with peaks in their
spectral energy distributions around 25 micron or longward of 60 micron,
respectively. Quantitative analysis indicates that this distribution relates to
a substantial dispersion in the strength of the cool dust component: broad-line
radio galaxies are relatively poor in large-scale dust. Possibly they have
undergone a different merger evolution, or are relatively old AGN.


title: The SAURON project. II. Sample and early results

abstract:
  Early results are reported from the SAURON survey of the kinematics and
stellar populations of a representative sample of nearby E, S0 and Sa galaxies.
The survey is aimed at determining the intrinsic shape of the galaxies, their
orbital structure, the mass-to-light ratio as a function of radius, the age and
metallicity of the stellar populations, and the frequency of kinematically
decoupled cores and nuclear black holes. The construction of the representative
sample is described, and its properties are illustrated. A comparison with
long-slit spectroscopic data establishes that the SAURON measurements are
comparable to, or better than, the highest-quality determinations. Comparisons
are presented for NGC 3384 and NGC 4365 where stellar velocities and velocity
dispersions are determined to a precision of 6 km/s, and the h3 and h4
parameters of the line-of-sight velocity distribution to a precision of better
than 0.02. Extraction of accurate gas emission-line intensities, velocities and
line widths from the datacubes is illustrated for NGC 5813. Comparisons with
published line-strengths for NGC 3384 and NGC 5813 reveal uncertainties of <
0.1 A on the measurements of the Hbeta, Mgb and Fe5270 indices. Integral-field
mapping uniquely connects measurements of the kinematics and stellar
populations to the galaxy morphology. The maps presented here illustrate the
rich stellar kinematics, gaseous kinematics, and line-strength distributions of
early-type galaxies. The results include the discovery of a thin, edge-on, disk
in NGC 3623, confirm the axisymmetric shape of the central region of M32,
illustrate the LINER nucleus and surrounding counter-rotating star-forming ring
in NGC 7742, and suggest a uniform stellar population in the decoupled core
galaxy NGC 5813.


title:
C star survey of the Local Group Galaxies. III The Sagittarius dwarf
  irregular and Leo I dwarf spheroidal galaxies

abstract:
  We present the latest results of our ongoing homogeneous cool C star survey
of Local Group dwarf galaxies. We apply our two color photometric technique to
the study of two small galaxies: the Sagittarius dwarf (SagDIG) and Leo I. We
identify 16 C stars in SagDIG and 13 C stars in Leo I. Even though both
galaxies have a known C star population, we identify 7 previously unknown C
stars in each galaxy. The photometric properties of all the known C stars in
each galaxy are presented. It is shown that our definition of a C star, based
on our photometric criteria, produces a subset of carbon stars with homogeneous
properties useful for population comparison.


title: Type 1 AGN Unification

abstract:
  The model I recently proposed for the structure of quasars offers to unify
the many aspects of Type 1 AGN: emission lines, absorption lines and reflection
features. This makes the model heavily overconstrained by observation and
readily tested.
  Here I first outline the model, and then concentrate on how the model answers
objections raised since publication - with many of the tests being reported at
this meeting. I then begin to explore how these and future tests can
discriminate between this wind model and 3 well-defined alternatives.


title: The Red-Sequence Cluster Survey: first lensing results

abstract:
  The Red-Sequence Cluster Survey (RCS) is a 100 deg^2 galaxy cluster survey
designed to provide a large sample of optically selected clusters of galaxies
with redshifts 0.1<z<1.4. The survey data are also useful for a variety of
lensing studies. Several strong lensing clusters have been discovered so far,
and follow up observations are underway. In these proceedings we present some
of the first results of a weak lensing analysis based on ~24 deg^2 of data. We
have detected the lensing signal induced by intervening large scale structure
(cosmic shear) at high significance, and find \sigma_8=0.81^{+0.14}_{-0.19}
(95% confidence; for a LCDM cosmology. Another application of these data is the
study of the average properties of dark matter halos surrounding galaxies. We
study the lensing signal from intermediate redshift galaxies with 19.5<R_C<21
using a parametrized mass model for the galaxy mass distribution. The analysis
yields a mass weighted velocity dispersion of 111+-5 km/s. In addition we have
constrained for the first time the extent of dark matter halos, and find a
robust upper limit for the truncation parameter s<470 h^{-1} kpc (99.7%
confidence). The biasing properties of these galaxies as a function of scale
are also studied. The RCS data allow us to measure the ratio of the bias
parameter b and the galaxy-mass cross-correlation coefficient r. The results
are consistent with a scale-independent value of b/r, for which we find
b/r=1.05^{+0.12}_{-0.10}.


title: In.XS: project for a future spaceborne hard X-ray all-sky survey

abstract:
  The latest all-sky survey in hard X-ray band was performed by the HEAO-1
satellite (13-80 keV) with an angular resolution of 24x48 arcmin. A diffuse
hard X-Ray background (HXB) was detected between 3 and 50 keV. The main
scientific goal of In.XS is to resolve a large fraction of this HXB into
individual sources.
  As no distortion by Compton up-scattering is seen in the spectrum of the
microwave background, the hard X-ray background is believed to be mainly due to
point sources. Type I Active Galactic Nuclei (AGN) have softer X-ray spectra
than the hard X-ray background, so other sources must be considered, like faint
Type II or absorbed AGN. These could be distinguished through hard X-ray
spectroscopic or hardness ratio observations.
  Here we present In.XS - a mission concept designed to conduct the first
imaging all-sky hard X-ray (2-80 keV) survey. The angular resolution of nearly
1 arcmin and good sensitivity at high energies is provided by the latest
multilayer focussing mirrors, with semiconductor-based (GaAs) arrays of
detectors. We also describe the mission operations, and how the all-sky survey
will be complemented by follow-up pointed observations of selected fields. The
good angular resolution will allow correlations and identification with objects
seen at other wavelengths. In addition, since a large fraction of the Type II
AGN luminosity is emitted in the hard X-ray band, this survey will provide a
large unbiased sample of the AGN population. This may provide constraints on
AGN evolution through the possible observation of a turnover in deep field
source statistics.


title: Infrared FeII Emission in Narrow-Line Seyfert 1 Galaxies

abstract:
  We obtained 0.8-2.4 micron spectra at a resolution of 320 km/s of four
narrow-line Seyfert 1 galaxies in order to study the near-infrared properties
of these objects. We focus on the analysis of the FeII emission in that region
and the kinematics of the low-ionization broad lines. We found that the 1
micron FeII lines (9997 A, 10501 A, 10863 A and 11126 A) are the strongest FeII
lines in the observed interval. For the first time, primary cascade lines of
FeII arising from the decay of upper levels pumped by Ly-alpha fluorescence are
resolved and identified in active galactic nuclei. Excitation mechanisms
leading to the emission of the 1 micron FeII features are discussed. A
combination of Ly-alpha fluorescence and collisional excitation are found to be
the main contributors. The flux ratio between near-IR FeII lines varies from
object to object, in contrast to what is observed in the optical region. A good
correlation between the 1 micron and optical FeII emission is found. This
suggests that the upper z4Fo and z4Do levels from which the bulk of the optical
lines descend are mainly populated by the transitions leading to the 1 micron
lines. The width and profile shape of FeII 11127, CaII 8642 and OI 8446 are
very similar but significantly narrower than Pa-beta, giving strong
observational support to the hypothesis that the region where FeII, CaII and OI
are produced are co-spatial, interrelated kinematically and most probably
located in the outermost portion of the BLR.


title:
Total linear polarization in the OH maser W75N: VLBA polarization
  structure

abstract:
  W75N is a star-forming region containing various ultracompact HII regions and
OH, water, and methanol maser emission. Our VLBA map shows that the OH masers
are located in a thin disk rotating around an O-star which is the exciting star
of the ultracompact HII region VLA1. A separate set of maser spots is connected
with the ultracompact HII region VLA2. The radial velocity of OH maser spots
varies across the disk from 3.7 km/s to 10.9 km/s. The diameter of the disk is
4000 A.U. All maser spots are strongly polarized. This are the first OH masers
showing nearly 100 per cent linear polarization in several spots. Two maser
spots seem to be Zeeman pairs corresponding to a magnetic field of 5.2 mgauss
and 7.7 mgauss, and in one case we tentatively found a Zeeman pair consisting
of two linearly polarized components. The linearly polarized maser spots are
shown to be sigma-components which is the case of the magnetic field being
perpendicular to the line of sight. The direction of the magnetic field as
determined from linearly polarized spots is perpendicular to the plane of the
disk, although the galactic Faraday rotation may significantly affect this
conclusion.


title: FUSE observations of the Blue Compact Dwarf Galaxy Mrk 59

abstract:
  New FUSE far-UV spectroscopy of the nearby metal-deficient (Zsun/8) cometary
Blue Compact Dwarf (BCD) galaxy Markarian (Mrk) 59 is discussed. The data are
used to investigate element abundances in its interstellar medium. The H I
absorption lines are characterized by narrow cores which are interstellar in
origin and by broad wings which are stellar in origin. The mean interstellar H
I column density is ~ 7x10E20 cm-2 in Mrk 59. No H2 lines are seen and N(H2) is
< 10E15 cm-2 at the 10 sigma level. The lack of diffuse H2 is due to the
combined effect of a strong UV radiation field which destroys the H2 molecules
and a low metallicity which leads to a scarcity of dust grains necessary for H2
formation. P-Cygni profiles of the S VI 933.4, 944.5 A and O VI 1031.9, 1037.6
A lines are seen, indicating the presence of very hot O stars and a stellar
wind terminal velocity of ~ 1000 km/s. By fitting the line profiles with
multiple components having each a velocity dispersion b = 7 km/s and spanning a
radial velocity range of 100 km/s, some of which can be saturated, we derive
heavy element abundances in the neutral gas. We find log N(O I)/N(H I) =
-5.0+/-0.3 or [O I/H I] = -1.5 for the neutral gas, about a factor of 10 below
the oxygen abundance of the supergiant H II region, implying self-enrichment of
the latter.


title:
The N/O abundance ratio in the lowest-metallicity blue compact dwarf
  galaxies

abstract:
  The results of the N/O abundance determination in a sample of low-metallicity
blue compact dwarf (BCD) galaxies based on new spectroscopic observations with
large telescopes (Keck, VLT, MMT, 4m KPNO) are presented. We show that the N/O
abundance ratio is constant at lowest metallicities < Zsun/20, confirming
previous findings and strongly supporting the origin of nitrogen as a primary
element.


title:
What Do We Expect to Learn from Very High Energy Cosmic Ray
  Observations?

abstract:
  By a short tour through the exciting field of very high-energy and ultra
high-energy cosmic rays studies, a brief review is given about the current
questions approached, in particular by the KASCADE experiment and the Pierre
Auger project. The present status of the investigations of the knee region of
the cosmic ray spectrum by KASCADE is presented and open problems are
discussed.


title:
A New Class of High-Mass X-ray Binaries: Implications for Core Collapse
  and Neutron-Star Recoil

abstract:
  We investigate an interesting new class of high-mass X-ray binaries (HMXBs)
with long orbital periods (P_orb > 30 days) and low eccentricities (e <~ 0.2).
The orbital parameters suggest that the neutron stars in these systems did not
receive a large impulse, or ``kick,'' at the time of formation. We develop a
self-consistent phenomenological picture wherein the neutron stars born in the
observed wide HMXBs receive only a small kick (<~ 50 km/s), while neutron stars
born in isolation, in the majority of low-mass X-ray binaries, or in many of
the well-known HMXBs with P_orb <~ 30 days receive the conventional large
kicks, with a mean speed of ~ 300 km/s. We propose that the magnitude of the
natal kick to a neutron star born in a binary system depends on the rotation
rate of the pre-collapse core. We further suggest that the rotation rate of the
core is a strong, well-defined function of the evolutionary path of the
progenitor star.


title: The theory of CMB anisotropies

abstract:
  This is a review of the theory of CMB anisotropies, an updated version of a
course given at the troisieme cycle de la Suisse Romande. An introduction to
gauge invariant cosmological perturbation theory is given and the theory CMB
anisotropies is develiped in this context. Simple analytical approximations for
the acoustic peak positions for adiabatic and isocurvature perturbations are
derived. Silk damping is discussed by an analytic approximation. A short
description of the present status of observations and parameter estimation
followed by a critical discussion terminate the review. The full system of
differential equations for CMB anisotropies and polarization needed in a
numerical treatment is also developed and given in an appendix.


title: X-ray Emission Processes in Radio Jets

abstract:
  The emission processes responsible for the observed X-rays from radio jets
are commonly believed to be non-thermal, but in any particular case, it is
unclear if synchrotron emission or one or more varieties of inverse Compton
emission predominates. We present a formulation of inverse Compton emission
from a relativistically moving jet (``IC/beaming'') which relies on radio
emitting synchrotron sources for which the energy densities in particles and
fields are comparable. We include the non-isotropic nature of inverse Compton
scattering of the relativistic electrons on photons of the cosmic microwave
background (CMB) and provide beaming parameters for a number of jets. A list of
X-ray emitting jets is given and the jets are classified on the basis of their
morphology and spectral energy distribution to determine their likely emission
process. We conclude that these jets have significant bulk relativistic
velocities on kpc scales; that higher redshift sources require less beaming
because the energy density of the CMB is significantly greater than locally;
and that for some nearby sources, synchrotron X-ray emission predominates
because the jet makes a large angle to the line of sight.


title:
Hydrodynamical Simulations of the Stream-Core Interaction in the Slow
  Merger of Massive Stars

abstract:
  We present detailed simulations of the interaction of a stream emanating from
a mass-losing secondary with the core of a massive supergiant in the slow
merger of the two stars inside a common envelope. The dynamics of the stream
can be divided into a ballistic phase, starting at the L_1 point, and a
hydrodynamical phase where the stream interacts strongly with the core.
Considering the merger of a 1 and 5Msun star with a 20Msun evolved supergiant,
we present two-dimensional hydrodynamical simulations using the PROMETHEUS code
to demonstrate how the penetration depth and post-impact conditions depend on
the initial properties of stream material (e.g. entropy, angular momentum,
stream width) and the properties of the core (e.g. density structure and
rotation rate). Using these results, we present a fitting formula for the
entropy generated in the stream--core interaction and a recipe for the
determination of the penetration depth based on a modified Bernoulli integral.


title:
Constraints on Disk Sizes Around Young Intermediate-Mass Stars: Nulling
  Interferometric Observations of Herbig Ae Objects

abstract:
  Physical models of circumstellar disks surrounding pre-main sequence stars
are currently constrained primarily by the spectral energy distribution (SED)
of the system. Here we present first results from a survey of nearby Herbig Ae
stars using nulling interferometry. We measure the spatial extent of the mid-IR
emission for the stars HD 150193, HD 163296, and HD 179218. The results
indicate the size of mid-infrared emission around Herbig Ae stars may be much
smaller than current models predict. The observations constrain ~90% of the 10
micron flux to be within an approximately 20 AU diameter region, providing
significant spatial limits for disk models. These results demonstrate the
scientific potential for nulling interferometry to study circumstellar disks
with better spatial discernment than is possible with standard mid-infrared
imaging.


title: Nucleosynthesis Clocks and the Age of the Galaxy

abstract:
  Nucleocosmochronology involves the use of the abundances of radioactive
nuclear species and their radiogenic decay daughters to establish the finite
age of the elements and the time scale for their formation. While there exist
radioactive products of several specific nucleosynthesis mechanisms that can
reveal the histories of these mechanisms, it is the long lived actinide
isotopes {232}Th, {235}U, and {238}U, formed in the r-process, that currently
play the major role in setting the time scale of Galactic nucleosynthesis. Age
determinations in the context of Galactic chemical evolution studies are
constrained by intrinsic model uncertainties. Recent studies have rather taken
the alternative approach of dating individual stars. Thorium/europium dating of
field halo stars and globular cluster stars yields ages on the order of 15 +/-
4 Gyr. A solid lower limit on stellar ages is available as well, for stars for
which one both knows the thorium abundance and has an upper limit on the
uranium abundance. For the cases of the two extremely metal deficient field
halo stars CS 22892-052 and HD 115444, lower limits on the nuclear age of
Galactic matter lie in the range 10-11 Gyr. Th/U dating of the star CS 31082-00
gives an age of 12.5 +/- 3 Gyr. Observations of thorium and uranium abundances
in globular cluster stars should make possible nuclear determinations of the
ages of clusters that can be compared with ages from conventional stellar
evolution considerations.


title: A Chandra X-ray Study of Cygnus A - II. The Nucleus

abstract:
  We report Chandra ACIS and quasi-simultaneous RXTE observations of the
nearby, powerful radio galaxy Cygnus A, with the present paper focusing on the
properties of the active nucleus. In the Chandra observation, the hard (> a few
keV) X-ray emission is spatially unresolved with a size \approxlt 1 arcsec (1.5
kpc, H_0 = 50 km s^-1 Mpc^-1) and coincides with the radio and near infrared
nuclei. In contrast, the soft (< 2 keV) emission exhibits a bi-polar nebulosity
that aligns with the optical bi-polar continuum and emission-line structures
and approximately with the radio jet. In particular, the soft X-ray emission
corresponds very well with the [O III] \lambda 5007 and H\alpha + [N II]
\lambda\lambda 6548, 6583 nebulosity imaged with HST. At the location of the
nucleus there is only weak soft X-ray emission, an effect that may be intrinsic
or result from a dust lane that crosses the nucleus perpendicular to the source
axis. The spectra of the various X-ray components have been obtained by
simultaneous fits to the 6 detectors. The compact nucleus is detected to 100
keV and is well described by a heavily absorbed power law spectrum with
\Gamma_h = 1.52^{+0.12}_{-0.12} (similar to other narrow line radio galaxies)
and equivalent hydrogen column N_H (nuc) = 2.0^{+0.1}_{-0.2} \times 10^{23}
cm^-2.
  (Abstract truncated).


title:
The polarization properties of Broad Absorption Line QSOs: observational
  results

abstract:
  Correlations between BAL QSO intrinsic properties and polarization have been
searched for. Some results are summarized here, providing possible constraints
on BAL outflow models.


title: Cosmology with Galaxy Clusters in the XMM Large-Scale Structure Survey

abstract:
  The upcoming XMM Large Scale Structure Survey (XMM-LSS) will ultimately
provide a unique mapping of the distribution of X-ray sources in a contiguous
64 sq. deg. region. In particular, it will provide the 3-dimensional location
of about 900 galaxy clusters out to a redshift of about 1. We study the
prospects that this cluster catalogue offers for measuring cosmological
parameters. We use the Press-Schechter formalism to predict the counts of
clusters and their X-ray properties in several CDM models. We compute the
detection efficiency of clusters, using realistic simulations of XMM X-ray
images, and study how it differs from a conventional flux limit. We compute the
expected correlation function of clusters using the extended halo model, and
show that it is expected to evolve very little out to z~2, once the selection
function of the survey is taken into account. The shape and the amplitude of
the correlation function can be used to brake degeneracies present when cluster
counts alone are considered. Ignoring systematic uncertainties, the combination
of cluster counts evolution and of the correlation function yields measurements
of Omega_m, sigma_8 and Gamma with a precision of about 15%, 10% and 35%,
respectively, in a LCDM model. This combination will also provide a consistency
check for the LCDM model, and a discrimination between this model and the OCDM
model. The XMM-LSS will therefore provide important constraints on cosmological
parameters, complementing that from other methods such as the Cosmic Microwave
Background. We discuss how these constraints are affected by instrumental
systematics and by the uncertainties in the scaling relations of clusters.


title: Evolution of massive binary black holes

abstract:
  Since many or most galaxies have central massive black holes (BHs), mergers
of galaxies can form massive binary black holes (BBHs). In this paper, we study
the evolution of massive BBHs in realistic galaxy models, using a
generalization of techniques used to study tidal disruption rates around
massive BHs. The evolution of BBHs depends on BH mass ratio and host galaxy
type. BBHs with very low mass ratios (say, $\la$ 0.001) are hardly ever formed
by mergers of galaxies because the dynamical friction timescale is too long for
the smaller BH to sink into the galactic center within a Hubble time. BBHs with
moderate mass ratios are most likely to form and survive in spherical or nearly
spherical galaxies and in high-luminosity or high-dispersion galaxies; they are
most likely to have merged in low-dispersion galaxies (line-of-sight velocity
dispersion $\la$ 90 km/s) or in highly flattened or triaxial galaxies. The
semimajor axes and orbital periods of surviving BBHs are generally in the range
10^{-3}-10 pc and 10-10^5 yr; and they are larger in high-dispersion galaxies
than in low-dispersion galaxies, larger in nearly spherical galaxies than in
highly flattened or triaxial galaxies, and larger for BBHs with equal masses
than for BBHs with unequal masses. The orbital velocities of surviving BBHs are
generally in the range 10^2-10^4 km/s. The methods of detecting surviving BBHs
are also discussed. If no evidence of BBHs is found in AGNs, this may be either
because gas plays a major role in BBH orbital decay or because nuclear activity
switches on soon after a galaxy merger, and ends before the smaller BH has had
time to spiral to the center of the galaxy.


title: The Rest-Frame Extreme Ultraviolet Spectral Properties of QSOs

abstract:
  We use a sample of 332 Hubble Space Telescope spectra of 184 QSOs with z >
0.33 to study the typical ultraviolet spectral properties of QSOs, with
emphasis on the ionizing continuum. Our sample is nearly twice as large as that
of Zheng et al. (1997) and provides much better spectral coverage in the
extreme ultraviolet (EUV). The overall composite continuum can be described by
a power law with index alpha_EUV = -1.76 +/- 0.12 (f_nu ~ nu^alpha) between 500
and 1200 Angstroms. The corresponding results for subsamples of radio-quiet and
radio-loud QSOs are alpha_EUV = -1.57 +/- 0.17 and alpha_EUV = -1.96 +/- 0.12,
respectively. We also derive alpha_EUV for as many individual objects in our
sample as possible, totaling 39 radio-quiet and 40 radio-loud QSOs. The typical
individually measured values of alpha_EUV are in good agreement with the
composites. We find no evidence for evolution of alpha_EUV with redshift for
either radio-loud or radio-quiet QSOs. However, we do find marginal evidence
for a trend towards harder EUV spectra with increasing luminosity for
radio-loud objects. An extrapolation of our radio-quiet QSO spectrum is
consistent with existing X-ray data, suggesting that the ionizing continuum may
be represented by a single power law. The resulting spectrum is roughly in
agreement with models of the intergalactic medium photoionized by the
integrated radiation from QSOs.


title: Optical-NIR Color Gradients in Early Type Galaxies at z \leq 1.0

abstract:
  Recent studies based on line indices of nearby early-type galaxies suggest
that stars in the galaxies' inner part may be younger and more metal rich than
stars in the outer part. If confirmed, the finding has a profound implication
for the formation and evolution of early-type galaxies, since such age
gradients naturally arise if merging played an important role in their
formation/evolution. As an indpendent test for the existence of the age
gradient, we investigate the optical-NIR color gradients of six field
early-type galaxies at z \simeq 0.4 -- 1.0 where the age gradient is expected
to be detectable when combined with z=0 calibrations. By utilizing HST NICMOS
H-band imaging along with WFPC2 optical data, we obtain a broad wavelength
baseline, giving results that are sensitive to the expected age gradient. When
compared with simple model predictions, five of the objects show negligible age
gradients and are metallicity gradient dominated, while the remaining object
shows a color gradient consistent with the age+metallicity gradient picture.
Our results suggest that stars within early-type galaxies may be coeval at z
\sim 1, but sprinkling of young stars might have occured at z < 1.


title: The `remarkable' M31 globular cluster 037-B327 revisited

abstract:
  The M31 globular cluster candidate 037-B327 has long been known to be an
extremely red, non-stellar object. The first published spectrum of this object
is used to confirm that it is a globular cluster belonging to M31, with rather
typical values of v_r = -338 +/- 12 km/s and [Fe/H]= -1.07 +/- 0.20 dex. Using
the spectroscopic metallicity to predict the intrinsic colours, we derive a
reddening value of E(B-V)=1.30 +/- 0.04 in good agreement with the value
obtained using reddening-free parameters. The extinction-corrected magnitude of
037-B327 is V_0=12.73 (absolute magnitude M_V = -11.74), which makes it the
most luminous globular cluster in M31. We examine van den Bergh's (1968)
argument regarding the brightest and most-reddened globular cluster in in M31;
we find that the brightest clusters are more heavily-reddened than average, but
this can be explained by selection effects rather than a different R_V in M31.


title:
Tentative Detection of Electric Dipole Emission from Rapidly Rotating
  Dust Grains

abstract:
  We present the first tentative detection of spinning dust emission from
specific astronomical sources. All other detections in the current literature
are statistical. The Green Bank 140 foot telescope was used to observe 10 dust
clouds at 5, 8, and 10 GHz. In some cases, the observed emission was consistent
with the negative spectral slope expected for free-free emission (thermal
bremsstrahlung), but in two cases it was not. One HII region yields a rising
spectrum, inconsistent with free-free or synchrotron emission at the 10 sigma
level. One dark cloud (L 1622) has a similar spectrum with lower significance.
Both spectra are consistent with electric dipole emission from rapidly rotating
dust grains ("spinning dust"), as predicted by Draine & Lazarian.


title:
The Distance to SN 1999em in NGC 1637 from the Expanding Photosphere
  Method

abstract:
  We present 30 optical spectra and 49 photometric epochs sampling the first
517 days after discovery of supernova (SN) 1999em, and derive its distance
through the expanding photosphere method (EPM). SN 1999em is shown to be a Type
II-plateau (II-P) event, with a photometric plateau lasting until about 100
days after explosion. We identify the dominant ions responsible for most of the
absorption features seen in the optical portion of the spectrum during the
plateau phase. We find the distance to SN 1999em to be D = 8.2 +/- 0.6 Mpc,
with an explosion date of 5.3 +/- 1.4 days before discovery.
  We examine potential sources of systematic error in EPM-derived distances,
and find the most significant to result from uncertainty in the theoretical
modeling of the flux distribution emitted by the SN photosphere (i.e., the
``flux dilution factor''). We compare previously derived EPM distances to 5 SNe
II in galaxies for which a recently revised Cepheid distance exists from the
HST Key Project and find D(Cepheids) / D(EPM) = 0.96 +/- 0.09. Finally, we
investigate the possible use of SNe II-P as standard candles and find that for
8 photometrically confirmed SNe II-P with previously derived EPM distances and
SN 1999em, the mean plateau absolute brightness is M_V(plateau) = -16.4 +/- 0.6
mag, implying that distances good to ~30% (1-sigma) may be possible without the
need for a complete EPM analysis. At M_V(plateau) = -15.9 +/- 0.2 mag, SN
1999em is somewhat fainter than the average SN II-P. The general consistency of
absolute SNe II-P brightness during the plateau suggests that the standard
candle assumption may allow SNe II-P to be viable cosmological beacons at z >
2.


title:
Nested Bars in Disk Galaxies: No Offset Dust Lanes in Secondary Nuclear
  Bars

abstract:
  Under certain conditions, sub-kpc nuclear bars form inside large-scale
stellar bars of disk galaxies. These secondary bars spend a fraction of their
lifetime in a dynamically-decoupled state, tumbling in the gravitational field
of the outer bars. We analyze the flow pattern in such nested bar systems and
find that secondary bars differ fundamentally from their large-scale
counterparts. In particular the gas flow across the bar-bar interface in these
systems can be more chaotic or more regular in nature, and, contrary to
predictions, has no difficulty in penetrating the secondary bars. The outer
parts of both short and long nuclear bars (with respect to their corotation)
appear to be depopulated of gas, while deep inside them the flow exhibits low
Mach numbers and follows ovally-shaped orbits with little dissipation. We find
that gas-dominated and star-dominated nuclear bars avoid the bar-bar interface,
making both types of bars short relative to their corotation. Furthermore, our
earlier work has shown that dynamically-coupled secondary bars exhibit a
similarly relaxed low-dissipation flow as well. Therefore, no large-scale
shocks form in the nuclear bars, and consequently, no offset dust lanes are
expected there. We find that offset dust lanes cannot be used in the search for
secondary (nuclear) bars.


title: Simulating a white dwarf dominated halo

abstract:
  Halo initial mass functions (IMFs) heavily biased toward white dwarf (WD)
precursors ~1-8 Msun have been suggested as a suitable mechanism for explaining
MACHO events. However, by simple chemical evolution argument, Gibson & Mould
(1997; GM97) pointed out that such WD-heavy IMFs (wdIMF) cause the
overproduction of carbon and nitrogen. We re-examine this problem using
numerical simulations.


title:
Discovery of a Black-hole Mass - Period Correlation in Soft X-ray
  Transients and its Implication for Gamma-Ray Burst and Hypernova Mechanisms

abstract:
  We investigate the soft X-ray transients with black hole primaries which may
have been the sources of gamma-ray bursts and hypernovae earlier in their
evolution. We find that the black-hole mass increases with the orbital period
of the binary, both for systems with main-sequence donors and for those with
evolved donors. This correlation can be understood in terms of angular-momentum
support in the helium star progenitor of the black hole, if the systems with
shorter periods had more rapidly rotating primaries prior to their explosion:
centrifugal support will then prevent more of its mass from collapsing into the
black hole. This trend of more rapidly rotating stars in closer binaries is
very generally seen, and in the present case can be understood in terms of
spin-up during spiral in and subsequent tidal coupling. We investigate the
relation quantitatively and obtain reasonable agreement with the observed
mass-period correlation. A natural consequence of this observation is that
black holes formed in soft X-ray transients acquire significant Kerr
parameters. This makes them good sources of power for gamma-ray bursts and
hypernovae, via the Blandford-Znajek mechanism, and thus supports our model for
the origin of gamma-ray bursts in soft X-ray transients.


title: X-Rays from Isolated Black Holes in the Milky Way

abstract:
  Galactic stellar-population-synthesis models, chemical-enrichment models, and
long-duration Bulge microlensing events indicate about N_tot=(0.1-1) billion
stellar-mass black holes reside in our Galaxy. We study X-ray emission from
accretion from the interstellar medium on to isolated black holes. Although
isolated black holes may be fewer in number than neutron stars, N_NS ~ 1
billion, their higher masses, <M>~9 M_sun, and smaller space velocities, v ~ 40
km/s, result in Bondi-Hoyle accretion rates ~4.E3 times higher than for neutron
stars. We estimate that ~1.E4 N_9 isolated black holes within the Milky Way
should accrete at > 1.E15 g/s, comparable to accretion rates inferred for
black-hole X-ray binaries given a total number of black holes N_tot= N_9 1.E9.
If black holes accrete at efficiencies only ~1.E-4(N_NS/N_tot)^0.8 of the
neutron-star accretion efficiency, a comparable number of each may be
detectable. We make predictions for the number of isolated accreting black
holes in our Galaxy which can be detected with X-ray surveys as a function of
efficiency, concluding that all-sky surveys at a depth of F = f 1.E-15
erg/cm^2/s/dex can find N(>F)~ 1.E4 N_9 (e5/f)^1.2 isolated accreting black
holes for a velocity dispersion of 40 km/s and X-ray accretion efficiency = e5
1.E-5. Deeper surveys of the Galactic plane with Chandra and XMM-Newton may
find tens of these objects per year, depending on the efficiency. We argue that
a minimum mass can be derived for microlensing black-hole candidates if they
are detected in the X-ray.


title:
Optical and Near-IR Imaging of Ultra Steep Spectrum Radio Sources - The
  K-z diagram of radio and optically selected galaxies

abstract:
  We present optical and/or near-IR images of 128 ultra steep spectrum (USS)
radio sources. Roughly half of the objects are identified in the optical images
(R <~ 24), while in the near-IR images, >94% are detected at K<~ 22. The mean
K-magnitude is K=19.26 within a 2" diameter aperture. The distribution of R-K
colors indicates that at least 1/3 of the objects observed have very red colors
(R-K>5). The major axes of the identifications in K-band are preferentially
oriented along the radio axes, with half of them having compact morphologies.
  The 22 sources with spectroscopic redshifts and K-band magnitudes follow the
K-z relation found from previous radio samples, but with a larger scatter. We
argue that this may be due to a dependence of K-magnitude on the radio power,
with the highest radio power sources inhabiting the most massive host galaxies.
We present a composite K-z diagram of radio-loud and radio-quiet galaxies,
selected from the HDF-North and the Hawaii surveys. Out to z <~ 1, the
radio-loud galaxies trace the bright envelope of the radio quiet galaxies,
while at z >~ 1, the radio-loud galaxies are >~ 2 magnitudes brighter. We argue
that this is not due to a contribution from the AGN or emission lines. This
difference strongly suggests that radio galaxies pinpoint the most massive
systems out to the highest known redshifts, probably due to the mutual
correlation of the mass of the galaxy and the radio power on the mass of the
central black hole.


title: The Evolution of Magnetic Fields in Galaxy Clusters

abstract:
  Cosmological simulations of magnetic fields in galaxy clusters show that
remarkable agreement between simulations and observations of Faraday rotation
and radio haloes can be achieved assuming that seed fields of 10^{-9} G were
present at redshifts 15-20. The structure of the seed field is irrelevant for
the final intracluster field. On average, the field grows exponentially with
decreasing cluster redshift, but merger events cause steep transient increases
in the field strength. Typical field-reversal scales are of order 50 kpc/h. In
most cases, the intracluster fields are dynamically unimportant. Assuming
secondary electron models, the average structure of cluster radio haloes can
naturally be reproduced.


title: The ROSAT HRI Point Spread Function

abstract:
  A sample of the brightest point-like sources observed with the ROSAT-HRI were
analysed to asses on the intrinsic shape of the ROSAT-HRI Point Spread Function
(PSF). Almost all of the HRI observations collected during the ROSAT lifetime
are found to be artificially broadened by factors up two ~2 due to residual
errors in the ROSAT aspect solution. After correction by departing pointing
positions, the width of the core of the PSF is found to be less than 5 arcsec
(half energy width, HEW). On the basis of these results, an improved analytical
representation of the ROSAT-HRI PSF is provided. However, for most of the new
observations the source countrate is too weak to allow reliable recovering pf
the ROSAT-HRI resolution. Therefore, a series of examples (data, correction,
and theoretical PSF) are given in order to help the ROSAT user in determining
whether "his/her source" is extended or not.


title: Detection of an inner torus in the Proto planetary Nebulae OH231.8+4.2

abstract:
  We performed the first VLBI observations of the SiO v=1 and v=2 J=1--0 masers
in a Proto Planetary Nebula OH 231.8+4.2 (also known as the Rotten Egg nebula),
at milliarcsecond resolution. Only the v=2 maser transition was detected. We
detect several maser spots lying along a line which is almost perpendicular to
the axis of symmetry of the Nebula. We find that all the emission is
concentrated in an area of ~10 mas, indicating that the SiO masers are
originated very close to the surface of the star. One of the two emission areas
presents an elongated structure with a clear velocity gradient. The detected
emission is consistent with a torus, or disk, in rotation with a velocity of ~6
km/s and with an infall velocity of ~10 km/s.


title: Pre-FLAMES Survey: Observations of Selected Stellar Fields

abstract:
  This paper presents the first set of fully calibrated images and associated
stellar catalogs of the Pre-FLAMES survey being carried out by the ESO Imaging
Survey (EIS) project. The primary goal of this survey is to provide the ESO
community with data sets from which suitable target lists can be extracted for
follow-up observations with the new VLT facility FLAMES. For this purpose 160
stellar fields have been selected for observations in B, V and I using the
8kx8k Wide Field Imager (WFI) at the MPG/ESO 2.2 m telescope at La Silla. These
data have been used to assess the observing strategy adopted and to define
suitable reduction techniques and procedures for the preparation of input
catalogs for FLAMES. The images and catalogs presented here are publicly
available and can be requested from the URL address ``http://www.eso.org/eis''.


title: White dwarf cooling and large extra dimensions

abstract:
  Theories of fundamental interactions with large extra dimensions have
recently become very popular. Astrophysical bounds from the Sun, red-giants and
SN1987a have already been derived by other authors for the theory proposed by
Arkani-Hamed, Dimopoulos and Dvali. In this paper we consider G117-B15A
pulsating white dwarf (ZZ Ceti star) for which the secular rate at which the
period of its fundamental mode increases has been accurately measured and
claimed that this mode of G117-B15A is perhaps the most stable oscillation ever
recorded in the optical band. Because an additional channel of energy loss
(Kaluza-Klein gravitons) would speed up the cooling rate, one is able to use
the aforementioned stability to derive a bound on theories with large extra
dimensions. Within the framework of the theory with large extra dimensions
proposed by Arkani-Hamed, Dimopoulos and Dvali we find the lower bound on
string comapctification scale which is more stringent than solar or red-giant
bounds.


title: VIMOS IFU as a tool to observe the cores of high z clusters

abstract:
  Research on the core of medium and high z clusters of galaxies can derive
great benefits from integral field spectroscopy, and a key role in this respect
will be played by the Integral Field Unit (IFU) being developed by the VIRMOS
Consortium as part of the VIMOS spectrograph. After a brief technical outline
of the instrument, some of the problems to be addressed by data reduction
techniques are described, and the scientific issues to which VIMOS IFU is
likely to give its major contribution are pointed out.


title:
Higher order corrections to lensing parameters for extended
  gravitational lenses

abstract:
  We discuss the contribution to the characteristic lensing quantities, i.e.
the deflection angle and Einstein radius, due to the higher order terms (e.g.
the gravitomagnetic terms) considered in the lens potential.
  The cases we analyze are the singular isothermal sphere and the disk of
spiral galaxies. It is possible to see that the perturbative effects could be
of the order 10^{-3} with respect to the ordinary terms of weak field and thin
lens approximations, so that it is not a far hypothesis to obtain evidences of
them in a next future by suitable experiments.


title: Dwarf galaxies in the Local Group: the VLT perspective

abstract:
  Recent results on the evolution of Local Group dwarf galaxies obtained from
VLT imaging and spectroscopy are briefly reviewed, and prospects for dwarf
galaxy research at the VLT are discussed in the light of the current and
forthcoming instrumentation. Some aspects of future instrument developments,
such as deep wide-field imaging at both optical and near-infrared wavelengths
that may be of advantage for research on the evolution of dwarf galaxies, are
briefly discussed.


title:
Molybdenum Evidence for Inherited Planetary Scale Isotope Heterogeneity
  of the Protosolar Nebula

abstract:
  Isotope anomalies provide important information about early solar system
evolution. Here we report molybdenum isotope abundances determined in samples
of various meteorite classes. There is no fractionation of molybdenum isotopes
in our sample set within 0.1 permil and no contribution from the extinct
radionuclide 97Tc at mass 97 (97Tc/92Mo<3E-6). Instead, we observe clear
anomalies in bulk iron meteorites, mesosiderites, pallasites, and chondrites
characterized by a coupled excess in p- and r- or a mirror deficit in s-process
nuclides (Mo-HL). This large scale isotope heterogeneity of the solar system
observed for molybdenum must have been inherited from the interstellar
environment where the sun was born, illustrating the concept of ``cosmic
chemical memory''. The presence of molybdenum anomalies is used to discuss the
filiation between planetesimals.


title: The cluster environments of radio loud quasars

abstract:
  We have carried out multi-colour imaging of the fields of a statistically
complete sample of low-frequency selected radio loud quasars at 0.6<z<1.1, in
order to determine the characteristics of their environments. The largest radio
sources are located in the field, and smaller steep-spectrum sources are more
likely to be found in richer environments, from compact groups through to
clusters. This radio-based selection (including source size) of high redshift
groups and clusters is a highly efficient method of detecting rich environments
at these redshifts. Although our single filter clustering measures agree with
those of other workers, we show that these statistics cannot be used reliably
on fields individually, colour information is required for this.


title: Quintessence Cosmology and the Cosmic Coincidence

abstract:
  Within present constraints on the observed smooth energy and its equation of
state parameter, it is important to find out whether the smooth energy is
static (cosmological constant) or dynamic (quintessence). The most dynamical
quintessence fields observationally allowed are now still fast-rolling and no
longer satisfy the tracker approximation if the equation of state parameter
varies moderately with cosmic scale. We are optimistic about distinguishing
between a cosmological constant and appreciably dynamic quintessence, by
measuring average values for the effective equation of state parameter.
However, reconstructing the quintessence potential from observations of any
scale dependence appears problematic in the near future. For our flat universe,
at present dominated by smooth energy in the form of either a cosmological
constant (LCDM) or quintessence (QCDM), we calculate the asymptotic collapsed
mass fraction to be maximal at the observed smooth energy/matter ratio.
Identifying this collapsed fraction as a conditional probability for habitable
galaxies, we infer that the prior distribution is flat. Interpreting this prior
as a distribution over theories, rather than as a distribution over
unobservable subuniverses, leads us to heuristic predictions about the class of
future quantum cosmology theories and the static or quasi-static nature of the
smooth energy.


title: Constraints on (Omega,Lambda) from strong lensing clusters

abstract:
  We use three strong lensing clusters to constrain the cosmological parameters
Omega_m and Omega_lambda. Recent HST observations of galaxy clusters reveal a
large number of multiple images, which are predicted to be at different
redshifts. We showed in a previous work that if it is possible to measure
spectroscopically the redshift of many multiple images then one can constrain
(Omega_m,Omega_lambda) through ratios of angular diameter distances
independently of any external assumptions. Using three strong lensing clusters,
our combined results lead to tight constraints.


title: The Recurrent Nova U Scorpii - A Type Ia Supernova Progenitor

abstract:
  We derive the mass of the white dwarf in the eclipsing recurrent nova U Sco
from the radial velocity semi-amplitudes of the primary and secondary stars.
Our results give a high white dwarf mass of M_1 = 1.55 \pm 0.24M_\odot,
consistent with the thermonuclear runaway model of recurrent nova outbursts. We
confirm that U Sco is the best Type Ia supernova progenitor known, and predict
that the time to explosion is within ~700,000 years.


title: The Effect of Heating and Cooling on Scaling Laws of X-Ray Clusters

abstract:
  We present results of including heating and cooling in cosmological
simulations of the $\Lambda$CDM cosmology and demonstrate their effects on
scaling laws of galaxy clusters. The scaling relations when radiative cooling
is included are in good agreement with observations but the fraction of cooled
gas is on the upper limit allowed by observations. On the contrary, the
preheating model has a more realistic cooled fraction but the scaling relations
are less well produced.


title: Distinguishing Dark Matter from Modified Gravity

abstract:
  Dynamical mass discrepancies in galaxies have two possible explanations: the
existence of large amounts of dark matter or the breakdown of Newtonian
gravity. True dark matter halos of galaxies could differ in several respects
from apparent halos inferred from misinterpreted modified gravity, and we
discuss two observational tests to probe these differences. Modified gravity
gives generic, geometrical predictions for the shapes of apparent halos, and
also requires that the inferred excess mass strongly correlates with the
visible baryonic mass. Thus modified gravity is more easily falsified, but we
find both hypotheses to be consistent with the meager data on galaxy and
cluster halos; dark matter is not required by current data. We strongly
encourage the acquisition of more data, which could ultimately eliminate one or
other of these possibilities.


title:
FUSE Observations of the Cygnus Loop: OVI Emission from a Nonradiative
  Shock

abstract:
  We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of a
Balmer filament in the northeast region of the Cygnus Loop supernova remnant.
The data consist of one spectrum obtained through the 30"x30" (LWRS) aperture
and three spectra at adjacent positions obtained through the 4"x20" (MDRS)
aperture. The nonradiative shocks in the region giving rise to these faint
optical filaments produce strong OVI 1032,1038 emission, which is detected in
all the spectra. The OVI emission is resolved by FUSE into a strong component
centered at 0 km/s, and weaker components centered at +/- 140 km/s. The MDRS
spectra allow us to study the variation of OVI emission in the post-shock
structure. We find that the zero velocity emission is associated directly with
the Balmer filament shock, while the high velocity emission comes from a more
uniformly distributed component elsewhere along the line of sight. We also find
that the shocks producing the emission at +/- 140 km/s have velocities between
180 km/s and 220 km/s, if we assume that the ram pressure driving them is the
same as for the zero velocity component shock. In the context of the cavity
model for the Cygnus Loop, the interaction of the blast wave with the spherical
shell that forms most of the cavity wall can naturally give rise to the similar
red and blue-shifted components that are observed.


title: The Missing CV Population: Results From An Objective Prism Survey

abstract:
  We present the results of a search for cataclysmic variables (CVs) in the
Calan-Tololo survey. We detected a total number of 21 CVs, 12 of them are
previously unknown objects. Our results suggest that the mismatch between the
theoretically predicted sample and the observed one is not due to observational
bias but has to be resolved by a revision of the theoretical models.


title: Dust In I Zw 18 From Hubble Space Telescope Narrow Band Imaging

abstract:
  We present new WFPC2 narrow band imaging of the blue compact dwarf galaxy I
Zw 18, which is host to the lowest-metallicity HII regions known. Images at
H-alpha and H-beta are combined with archival broad band images to allow the
study of the ionized gas distribution and morphology. Analysis of the
H-alpha/H-beta flux ratio reveals significant enhancements in some areas of
both the ``Northwest'' and ``Southeast'' regions of the galaxy, with ratios
elevated to levels as high as 3.4. The H-alpha/H-beta ratio varies considerably
with position throughout the galaxy. Comparing this distribution with the
stellar distribution indicates that the regions of enhanced H-alpha/H-beta
ratio are not due to the effects of either collisional excitation or underlying
stellar absorption, and therefore are most likely interpreted as the presence
of dust. This dust has an estimated mass of (2-5)x10^3 solar masses, which is
consistent with the IRAS far-IR non-detection. Under the assumption that dust
traces the presence of molecular gas, these results suggest that the molecular
component of the ISM of I Zw 18, which is needed to fuel its active star
formation, is also very clumpy. Such a distribution would be consistent with
the recent FUSE non-detections of diffuse H_2.


title:
Gravity Waves from Rotating Neutron Stars and Evaluation of Fast Chirp
  Transform Techniques

abstract:
  X-ray observations suggest that neutron stars in low mass X-ray binaries
(LMXB) are rotating with frequencies from 300 - 600 Hz. These spin rates are
significantly less than the break-up rates for essentially all realistic
neutron star equations of state, suggesting that some process may limit the
spin frequencies of accreting neutron stars to this range. If the accretion
induced spin up torque is in equilibrium with gravitational radiation losses,
these objects could be interesting sources of gravity waves. I present a brief
summary of current measurements of neutron star spins in LMXBs based on the
observations of high-Q oscillations during thermonuclear bursts (so called
``burst oscillations''). Further measurements of neutron star spins will be
important in exploring the gravitational radiation hypothesis in more detail.
To this end I also present a study of fast chirp transform (FCT) techniques as
described by Jenet & Prince (2000) in the context of searching for the chirping
signals observed during X-ray bursts.


title:
The Supernova Remnant CTB104A : Magnetic Field Structure and Interaction
  with the Environment

abstract:
  We present new, high resolution 1420 and 408 MHz continuum images and HI and
12CO (J=1-0) spectral line maps of the diffuse supernova remnant CTB104A
(G93.7-0.3). Analysis of the complex continuum emission reveals no significant
spectral index variations across the remnant. Three prominences around CTB104A
are found to be related to the SNR, while one extension to the east is
identified as an HII region associated with a background molecular shell. Small
scale polarization and rotation measure (RM) structures are turbulent in
nature, but we find a well-ordered RM gradient across the remnant, extending
from southeast to northwest. This gradient does not agree with the direction of
the global Galactic magnetic field, but does agree with a large-scale RM
anomaly inferred from rotation measure data by Cleg et al. (1992). We show that
the observed morphology of CTB104A is consistent with expansion in a uniform
magnetic field, and this is supported by the observed RM distribution. By
modeling the RM gradient with a simple compression model we have determined the
magnetic field strength within the remnant as Bo ~ 2.3 micro G. We have
identified signatures of the interaction of CTB104A with the surrounding
neutral material, and determined its distance, from the kinematics of the HI
structure encompassing the radio emission, as 1.5 kpc. We also observed clear
breaks in the HI shell that correspond well to the positions of two of the
prominences, indicating regions where hot gas is escaping from the interior of
the SNR.


title: Interaction Models for GRB Afterglows

abstract:
  We review interaction models for GRB afterglows, with an eye on constraining
the nature of their progenitors and the geometry of explosion. Evidence is
presented for two types of progenitors. The radio afterglow of GRB 980425/SN
1998bw and the multi-frequency observations of GRB 970508 can be fitted by a
blast wave expanding into a wind-type medium, pointing to a massive star
progenitor. The broadband afterglow data of GRBs 990123 and 990510 are better
modeled by a jet expanding into a constant-density medium, implying a compact
star merger origin. Among other well observed GRBs, the jet model appears to be
more widely applicable than the wind model, although some cases are ambiguous.
The model fits often require a deviation of the energy distribution of the
radiating electrons from the commonly assumed single power-law form,
particularly for sources with a rapid decline and/or pronounced steepening in
the optical light curves. Transition to non-relativistic evolution has been
suggested as an alternative explanation for the light curve steepening,
although to produce steepening on the order of days or less would require very
high ambient densities, which are generally difficult to reconcile with radio
observations. Major open issues include the hydrodynamics of jet-ambient medium
interaction, a self-consistent determination of the electron energy
distribution, and the effects of pair production on the early afterglows which
are expected to be particularly large for the wind interaction model.