title:
Non-Axisymmetric g-Mode and p-Mode Instability in a Hydrodynamic Thin
  Accretion Disk

abstract:
  It has been suggested that quasi-periodic oscillations of accreting X-ray
sources may relate to the modes named in the title. We consider
non-axisymmetric linear perturbations to an isentropic, isothermal,
unmagnetized thin accretion disk. The radial wave equation, in which the number
of vertical nodes (n) appears as a separation constant, admits a wave-action
current that is conserved except, in some cases, at corotation. Waves without
vertical nodes amplify when reflected by a barrier near corotation. Their
action is conserved. As was previously known, this amplification allows the n=0
modes to be unstable under appropriate boundary conditions. In contrast, we
find that waves with n >0 are strongly absorbed at corotation rather than
amplified; their action is not conserved. Therefore, non-axisymmetric p-modes
and g-modes with n>0 are damped and stable even in an inviscid disk. This
eliminates a promising explanation for quasi-periodic oscillations in
neutron-star and black-hole X-ray binaries.


title: The Effect of a Radome on Submillimeter Site Testing Measurements

abstract:
  We evaluate the effect that radome transparency has on atmospheric opacity
measurements performed by the skydip technique. We show that, except at rather
high opacities, it is not sufficient to ignore losses in the radome (or
"window") during the data analysis and then subtract them off from the derived
atmospheric opacity. Perhaps surprisingly, unless radome transparency is
correctly modelled, the atmosphere will appear to have a minimum opacity that
is many times greater that the radome losses. Our conclusion is that some
previous site studies may have significantly underestimated the quality of the
best submillimeter sites, and that the difference between these sites and
poorer sites may be much greater that currently believed. We also show that
most of the residual 857 GHz opacity at the best sites, currently ascribed to
"dry-air opacity", can in fact be just an artefact caused by not properly
modelling the radome during the data analysis.


title:
Flux enhancement in the inner region of a geometrically and optically
  thick accretion disk

abstract:
  The surface flux (and the corresponding observed flux) of a geometrically
thick ``funnel'' shaped disk is computed taking into account the radiation
impinging on the surface from other parts of the disk. It is found that the
ratio of the maximum apparent luminosity to the real luminosity of the disk is
only a factor $\approx 5$ even when the opening angle of the disk is small
($\approx 15^o$). Thus, geometrically beamed emission from ``funnel'' shaped
sub-Eddington disks around stellar mass black holes, cannot explain the
Ultra-Luminous X-ray sources detected in nearby galaxies.


title: Nova Scorpii 1941 (V697 Sco): A Probable Intermediate Polar

abstract:
  V697 Sco, the remnant of Nova Scorpii 1941 and currently at V ~ 20.0, is
found from photometric observations to have the characteristics of an
intermediate polar (IP) with an orbital period (Porb) of 4.49 h and a rotation
period (Prot) of 3.31 h. It therefore appears to be a member of the rare class
of IPs where Prot ~ Porb, which are probably discless systems. The prominence
of the modulation at 0.5 Prot, and its orbital sidebands, indicates two-pole
accretion.


title: Temporal variation of coupling constants and nucleosynthesis

abstract:
  We investigate the triple-alpha process and the Oklo phenomenon to obtain
constraints on possible cosmological time variations of fundamental constants.
Specifically we study cosmological temporal constraints for the fine structure
constant and nucleon and meson masses.


title: Millisecond Radio Pulsars in 47 Tucanae

abstract:
  We review the properties of the 22 millisecond radio pulsars currently known
in the globular cluster 47 Tucanae, and their implications for the mass and gas
content of the cluster. Further details can be found in the publications from
this project to date (Camilo et al. 2000; Freire 2000; Freire et al. 2001a,b;
Freire et al. 2003). Throughout the review, we look ahead to the future results
anticipated from this fascinating cluster.


title:
The HST survey of the B2 sample of radio galaxies: detection of two
  optical jets

abstract:
  We present HST observations of previously undetected optical jets in the
low-luminosity radio galaxies B2 0755+37 and B2 1553+24. We show that there is
accurate spatial coincidence between optical and radio emission, implying that
the former is likely to be synchrotron radiation. The physical properties of
the jets are similar to those known previously: their radio-optical spectral
indices are ~0.7 and in B2 0755+37, the spectrum steepens between optical and
X-ray wavelengths. Our results support the hypothesis that optical emission is
detectable from jets orientated within ~20 degrees of the line of sight for the
B2 sample.


title:
The transition from Population III to normal galaxies: Ly-a and HeII
  1640 emission and the ionising properties of high redshift starburst galaxies

abstract:
  We examine spectral properties of the ionising continua, the Lyman-break, and
the Ly-a and HeII 1640 recombination lines in starbursts. The transition from
primordial galaxies to currently observed metallicities, is examined. For the
average properties of starbursts, the main findings are: 1) The Lyman continuum
flux increases with decreasing metallicity. For a universal Salpeter IMF from
1-100 Msun the enhancement reaches typically a factor of ~3 between solar
metallicity and Pop III objects. 2) While for metallicities Z >~ 1/50 Zsun the
amplitude of the Lyman-break depends little on Z, a reduction by a factor ~2 is
found at lower Z, due to the strong increase of the average stellar
temperature. 3) Using theoretical models and empirical constraints we discuss
the expected evolution of the hardness of He+ to H ionising photons with
metallicity and possible uncertainties. We also provide a simple estimate of
the possible impact of hot WR like stars on Q(He+)/Q(H) at very low
metallicities. 4) Calibrations for star formation rate determinations from
various recombination lines at all metallicities and for various IMFs are
derived.
  For young bursts the maximum Ly-a equivalent width is shown to increase
strongly with decreasing metallicity for the same IMF. However, for well known
reasons, the Ly-a emission predicted likely represents an upper limit.
Non-negligible HeII 1640 emission due to stellar photoionisation appears to be
limited to very low metallicities and Population III objects.(abridged
abstract)


title: Main-sequence stellar eruption model for V838 Mon

abstract:
  We propose that the energy source of the outburst of V838 Mon and similar
objects is an accretion event, i.e., gravitational energy rather than
thermonuclear runaway. We show that the merger of two main sequence stars, of
masses 1.5 Mo and 0.1-0.5 Mo can account for the luminosity, large radius, and
low effective temperture of V838 Mon and similar objects. Subsequent cooling
and gravitational contraction lead such objects to move along the Hayashi
limit, as observed. By varying the masses and types of the merging stars, and
by considering slowly expanding, rather than hydrostatic, envelopes, this model
can account for a large range in luminosities and radii of such outburst
events.


title:
A reinterpretation of Volcano Ranch lateral distribution measurements to
  infer the mass composition of cosmic rays

abstract:
  In the course of its operation, the Volcano Ranch array collected data on the
lateral distribution of showers produced by cosmic rays at energies above
$10^{17}$ {\rm eV}. From these data very precise measurements of the steepness
of the lateral distribution function, characterized by the $\eta$ parameter,
were made. The current availability of sophisticated hadronic interaction
models has prompted a reinterpretation of the measurements. We use the
interaction models {\sc qgsjet} and {\sc sibyll} in the {\sc aires} Monte Carlo
code to generate showers together with {\sc geant4} to simulate the response of
the detectors to ground particles. As part of an effort to estimate the primary
mass composition of cosmic rays at this energy range, we present the results of
our preliminary analysis of the distribution of $\eta$.


title: The Be/X-ray transient KS 1947+300

abstract:
  We present optical spectroscopy and optical and infrared photometry of the
counterpart to the transient X-ray source KS 1947+300. The counterpart is shown
to be a moderately reddened V=14.2 early-type Be star located in an area of low
interstellar absorption slightly above the Galactic plane. Changes in
brightness are accompanied by correlated reddening of the source, as is
expected in this kind of object. From intermediate resolution spectroscopy, we
derive a spectral type B0Ve. If the intrinsic luminosity of the star is normal
for its spectral type, KS 1947+300 is situated at a distance of ~10 kpc,
implying that its X-ray luminosity at the peak of the spring 2000 X-ray
outburst was typical of Type II outbursts in Be/X-ray transients. KS 1947+300
is thus the first Be/X-ray recurrent transient showing Type II outbursts which
has an almost circular orbit.


title: Globular Clusters in nearby Galaxy Cluster

abstract:
  The discovery of a large population of intra-cluster star clusters in the
central region of the Hydra I and Centaurus galaxy clusters is presented. Based
on deep VLT photometry (V,I), many star clusters have been identified not only
around the early-type galaxies, but also in the intra-cluster field, as far as
250 kpc from the galaxy centres. These intra-cluster globulars are
predominantly blue, with a siginificant fraction being even bluer than the
metal-poor halo clusters around massive galaxies. When interpreted as a
metallicity effect they would have iron abundances around [Fe/H] = -2 dex.
However, they might also be relatively young clusters which could have formed
in tidal tails during recent interactions of the central galaxies.


title: Dense Plasma Torus in the GPS Galaxy NGC 1052

abstract:
  We report results from nearly simultaneous pentachromatic VLBI observations
towa rds a nearby GPS galaxy NGC 1052. The observations at 1.6 and 4.8 GHz with
VSOP, and at 2.3, 8.4, and 15.4 GHz wit h VLBA, provide linear resolutions of
$\sim 0.1$ pc. Convex spectra of a double-sided jet imply that synchrotron
emission is obscured through foreground cold dense plasma, in terms of
free--free absorption (FFA). We found a central condensation of the plasma
which covers about 0.1 pc and 1 pc of the approaching and receding jets,
respectively. A simple model with a geometrically thick plasma torus
perpendicular to the jets is established to explain the asymmetric distribution
of FFA opacities.


title: Generalized Chaplygin gas and CMBR constraints

abstract:
  We study the dependence of the location of the Cosmic Microwave Background
Radiation (CMBR) peaks on the parameters of the generalized Chaplygin gas
model, whose equation of state is given by $p = - A/\rho^{\alpha}$, where $A$
is a positive constant and $0 < \alpha \le 1$. We find, in particular, that
observational data arising from Archeops for the location of the first peak,
BOOMERANG for the location of the third peak, supernova and high-redshift
observations allow constraining significantly the parameter space of the model.
Our analysis indicates that the emerging model is clearly distinguishable from
the $\alpha = 1$ Chaplygin case and the $\Lambda$CDM model.


title:
Fundamental parameters of Galactic luminous OB stars VI. Temperatures,
  masses and WLR of Cyg OB2 supergiants

abstract:
  We have analyzed six OB supergiants and one giant covering spectral types
from O3 to B1 in the Galactic OB association Cyg OB2 by means of an updated
version of FASTWIND (SAntolaya-Rey, Puls, Herrero, 1997, A&A 323, 348) that
includes an approximate treatment of metal line blocking and blanketing. This
large coverage in spectral type allows us to derive a new temperature scale for
Galactic O supergiants that is lower than the one obtained by using pure H--He
models, either plane-parallel and hydrostatic or spherical with mass-loss. The
lower temperatures are thus a combined effect of line blanketing and the large
mass-loss rates. In some cases, the newly derived effective temperature is
reduced by up to 8000 K. Changes are larger for earlier stars with large
mass--loss rates. As a consequence, luminosities are modified as well, which
results in a lower number of emerging ionizing photons and reduces the mass
discrepancy. Although there are still significant differences between
spectroscopic and evolutionary masses, we do not find any obvious systematic
pattern of those differences. We derive mass--loss rates and the corresponding
wind momentum--luminosity relation for the analyzed stars. Although consistent
with previous results by Puls et al. (1996, A&A 305, 171) for Galactic stars,
our relation is better defined due to a reduction of errors related to stellar
distances and points to a possible separation between extreme Of stars (Of+,
Of*) and stars with more moderate morphologies. However this finding is only
tentative, as the statistics are still scarce.


title:
An estimate of the time variation of the O/H radial gradient from
  planetary nebulae

abstract:
  Radial abundance gradients are a common feature of spiral galaxies, and in
the case of the Galaxy both the magnitude of the gradients and their variations
are among the most important constraints of chemical evolution models.
Planetary nebulae (PN) are particularly interesting objects to study the
gradients and their variations. Owing to their bright emission spectra, they
can be observed even at large galactocentric distances, and the derived
abundances are relatively accurate, with uncertainties of about 0.1 to 0.2 dex,
particularly for the elements that are not synthesized in their progenitor
stars. On the other hand, as the offspring of intermediate mass stars, with
main sequence masses in the interval of 1 to 8 solar masses, they are
representative of objects with a reasonable age span. In this paper, we present
an estimate of the time variation of the O/H radial gradient in a sample
containing over 200 nebulae with accurate abundances. Our results are
consistent with a flattening of the O/H gradient roughly from -0.11 dex/kpc to
-0.06 dex/kpc during the last 9 Gyr, or from -0.08 dex/kpc to -0.06 dex/kpc
during the last 5 Gyr.


title:
Galaxy spectral parameterisation in the 2dF Galaxy Redshift Survey as a
  diagnostic of star formation history

abstract:
  We investigate the physical significance of a new spectral parameter, eta.
This parameter was defined using a Principal Component Analysis of the 2dF
Galaxy Redshift Survey, to retain astrophysical information while minimising
the effect of measurement uncertainties. We find that while eta is correlated
with morphological type, there is a large scatter in this relationship. A
tighter empirical relationship is found between eta and the equivalent width of
the Halpha line, suggesting a connection with the relative star formation rate.
We pursue this connection using spectral synthesis models. Using models in
which the star formation history is parameterised in terms of an exponentially
decreasing function of time, we find that there is a tight correlation between
eta and the ratio of the present to the past-averaged rate of star-formation,
often known as the ``birthrate'' parameter b. This correlation also holds in
models with much more complicated star formation histories, generated by a
semi- analytic model of galaxy formation based upon the hierarchical formation
scenario. There are two possible causes for the tight correlations we find
between eta and b in those galaxies with the most complex star formation
histories; Firstly, the spectra themselves may be degenerate to the actual
long-term star formation history of each galaxy in the optical wavelength range
probed by the 2dFGRS. Secondly, the birthrate parameter b may represent a
physically fundamental quality of galaxy halos -- their over-density relative
to the background density. We conclude that the tight connection with b makes
eta a physically meaningful, as well as convenient and robust, statistic for
galaxy parameterisation and classification. (abridged)


title: Cosmological Perturbations in Renormalization Group Derived Cosmologies

abstract:
  A linear cosmological perturbation theory of an almost homogeneous and
isotropic perfect fluid Universe with dynamically evolving Newton constant $G$
and cosmological constant $\Lambda$ is presented. A gauge-invariant formalism
is developed by means of the covariant approach, and the acoustic propagation
equations governing the evolution of the comoving fractional spatial gradients
of the matter density, $G$, and $\Lambda$ are thus obtained. Explicit solutions
are discussed in cosmologies where both $G$ and $\Lambda$ vary according to
renormalization group equations in the vicinity of a fixed point.


title: The Universe Was Reionized Twice

abstract:
  We show the universe was reionized twice, first at z~15-16 and second at z~6.
Such an outcome appears inevitable, when normalizing to two well determined
observational measurements, namely, the epoch of the final cosmological
reionization at z~6 and the density fluctuations at z~6, which in turn are
tight ly constrained by Lyman alpha forest observations at z~3. These two
observations most importantly fix the product of star formation efficiency and
ionizing photon escape fraction from galaxies at high redshift. To the extent
that the relative star formation efficiencies in gaseous minihalos with H2
cooling and large halos with atomic cooling at high redshift are still unknown,
the primary source for the first reionization could be Pop III stars either in
minihalos or in large halos. We show that gas in minihalos can be cooled
efficiently by H2 molecules and star formation can continue to take place
largely unimpeded throughout the first reionization period, thanks to two new
mechanisms for generating a high X-ray background during the Pop III era, put
forth here. Moreover, an important process for producing a large number of H2
molecules in relic HII regions of Pop III galaxies, first pointed out by
Ricotti, Gnedin, & Shull, is quantified here. It is shown that the Lyman-Werner
background may never build up during the Pop III era. The long cosmological
reionization and reheating history is complex. We discuss a wide range of
implications and possible tests for this new reionization picture. In
particular, Thomson scattering optical depth is increased to 0.10 +- 0.03,
compared to 0.027 for the case of only one rapid reionization at z=6. Upcoming
Microwave Anisotropy Probe observation of the polarization of the cosmic
microwave background should be able to distinguish between these two scenarios.


title: Kinematics and stellar populations of 17 dwarf early-type galaxies

abstract:
  We present kinematics and stellar population properties of 17 dwarf
early-type galaxies in the luminosity range -14> M_B> -19. Our sample fills the
gap between the intensively studied giant elliptical and Local Group dwarf
spheroidal galaxies. The dwarf ellipticals of the present sample have constant
velocity dispersion profiles within their effective radii and do not show
significant rotation, hence are clearly anisotropic. The dwarf lenticulars,
instead, rotate faster and are, at least partially, supported by rotation. From
optical Lick absorption indices, we derive metallicities and element
abundances. Combining our sample with literature data of the Local Group dwarf
spheroidals and giant ellipticals, we find a surprisingly tight linear
correlation between metallicity and luminosity over a wide range: -8> M_B> -22.
The alpha/Fe ratios of our dwarf ellipticals are significantly lower than the
ones of giant elliptical galaxies, which is in agreement with spectroscopy of
individual stars in Local Group dwarf spheroidals. Our results suggest the
existence of a clear kinematic and stellar population dichotomy between dwarf
and giant elliptical galaxies. This result is important for theories of galaxy
formation, because it implies that present-day dwarf ellipticals are not the
fossiled building blocks of giant ellipticals.


title:
X-ray lighthouses of the high-redshift Universe. Probing the most
  luminous z>4 Palomar Digital Sky Survey Quasars with Chandra

abstract:
  We present the results from exploratory Chandra observations of nine high-z
(z=4.1-4.5) optically selected quasars. These quasars, taken from the DPOSS,
are among the optically most luminous z>4 quasars known (M_B=-28.4 to -30.2).
All have been detected by Chandra in exposure times of 5-6 ks, tripling the
number of highly luminous quasars with X-ray detections at z>4. These quasars'
average broad-band SEDs are characterized by steeper aox values
(<aox>=-1.81+/-0.03) than those of lower-luminosity, lower-redshift samples of
quasars. We confirm the presence of a significant correlation between the UV
magnitude and soft X-ray flux previously found for z>4 quasars. The joint 2-30
keV rest-frame X-ray spectrum of the nine quasars is well parameterized by a
simple power-law model with Gamma=2.0+/-0.2, consistent with those of lower-z
quasars. No evidence for significant amounts of intrinsic absorption has been
found (N_H<8.8x10^21 cm^-2 at 90% confidence). In general, our results show
that z=4.1-4.5 quasars and local quasars have reasonably similar X-ray and
broad-band spectra (once luminosity effects are taken into account), suggesting
that the accretion mechanisms in these objects are similar. We also present
optical spectra for these quasars obtained with the HET; this is the first time
optical spectra have been published for seven of these objects. The objects
presented in this paper are among the best z>4 targets for X-ray spectroscopy
with XMM-Newton and next-generation large-area X-ray telescopes. These will
detect or constrain FeK_alpha emission lines down to rest-frame EWs of about 50
eV and intrinsic column densities down to N_H=a few x 10^21 cm^-2 at z=4. We
also present 45 new ROSAT upper limits for z>4 quasars and a likely (3sigma)
HRI detection of the blazar GB 1713+2148 at z=4.01.


title: High-redshift objects and the generalized Chaplygin gas

abstract:
  Motivated by recent developments in particle physics and cosmology, there has
been growing interest in an unified description of dark matter and dark energy
scenarios. In this paper we explore observational constraints from age
estimates of high-$z$ objects on cosmological models dominated by an exotic
fluid with equation of state $p = -A/\rho^{\alpha}$ (the so-called generalized
Chaplygin gas) which has the interesting feature of interpolating between
non-relativistic matter and negative-pressure dark energy regimes. As a general
result we find that, if the age estimates of these objects are correct, they
impose very restrictive limits on some of these scenarios.


title: Acceleration of ULtra High Energy Cosmic Rays: Cosmic Zevatrons?

abstract:
  In this lecture I outline some of the underlying physics issues associated
with accelerators plausibly capable of explaining the UHECRs up to ZeV
energies. I concentrate on the concentrate on mechanisms and their constraints,
but provide a brief background on on observations and the constraints they
supply, as well.


title: Mining Weak Lensing Surveys

abstract:
  We present a survey of the cosmological applications of the next generation
of weak lensing surveys, paying special attention to the computational
challenges presented by the number of galaxies, $N_{gal} ~$ 10$^{5}$. We focus
on optimal methods with no pixelization and derive a multigrid $P^3M$ algorithm
that performs the relevant computations in $O(N_{gal} \log N_{gal})$ time. We
test the algorithm by studying three applications of weak lensing surveys -
convergence map reconstruction, cluster detection and $E$ and $B$ power
spectrum estimation using realistic 1 deg^{2} simulations derived from N-body
simulations. The map reconstruction is able to reconstruct large scale features
without artifacts. Detecting clusters using only weak lensing is difficult
because of line of sight contamination and noise, with low completeness if one
desires low contamination of the sample. A power spectrum analysis of the
convergence field is more promising and we are able to reconstruct the
convergence spectrum with no loss of information down to the smallest scales.
The numerical methods used here can be applied to other data sets with same
$O(N\log N)$ scaling and can be generalised to a sphere.


title:
The Formation of Stellar Clusters in Turbulent Molecular Clouds: Effects
  of the Equation of State

abstract:
  We study numerically the effect of varying the equation of state (EOS) on the
formation of stellar clusters in turbulent molecular clouds. Our results show
that the EOS plays an important role in the fragmentation of the clouds, and
the determination of the initial mass function (IMF) of the protostellar cores.
Fragmentation decreases with increasing adiabatic index $\gamma$ in the range
$0.2 < \gamma < 1.4$, although the total amount of mass accreted appears to
remain roughly constant through that range, resulting in more massive cores at
higher $\gamma$. Fragmentation and collapse ceases entirely for $\gamma > 1.4$
as expected from analytic arguments. Primordial gas may have effective $\gamma
> 1$, in which case these results may help explain why models of the formation
of the first stars produce isolated, massive objects.


title:
Challenging cosmic ray propagation with antiprotons. Evidence for a
  "fresh" nuclei component?

abstract:
  Recent measurements of the cosmic ray (CR) antiproton flux have been shown to
challenge existing CR propagation models. It was shown that the reacceleration
models designed to match secondary to primary nuclei ratios (e.g.,
boron/carbon) produce too few antiprotons. Matching both the secondary to
primary nuclei ratio and the antiproton flux requires artificial breaks in the
diffusion coefficient and the primary injection spectrum suggesting the need
for other approaches.
  In the present paper we discuss one possibility to overcome these
difficulties. Using the measured antiproton flux AND B/C ratio to fix the
diffusion coefficient, we show that the spectra of primary nuclei as measured
in the heliosphere may contain a fresh local "unprocessed" component at low
energies perhaps associated with the Local Bubble, thus decreasing the measured
secondary to primary nuclei ratio. The independent evidence for SN activity in
the solar vicinity in the last few Myr supports this idea. The model reproduces
antiprotons, B/C ratio, and elemental abundances up to Ni (Z<=28). Calculated
isotopic distributions of Be and B are in perfect agreement with CR data. The
abundances of three "radioactive clock" isotopes in CR, 10Be, 26Al, 36Cl, are
all consistent and indicate a halo size z_h~4 kpc based on the most accurate
data taken by the ACE spacecraft.


title: Listening to the Universe with Gravitational-Wave Astronomy

abstract:
  The LIGO (Laser Interferometer Gravitational-Wave Observatory) detectors have
just completed their first science run, following many years of planning,
research, and development. LIGO is a member of what will be a worldwide network
of gravitational-wave observatories, with other members in Europe, Japan, and
-- hopefully -- Australia. Plans are rapidly maturing for a low frequency,
space-based gravitational-wave observatory: LISA, the Laser Interferometer
Space Antenna, to be launched around 2011. The goal of these instruments is to
inaugurate the field of {\it gravitational-wave astronomy}: using
gravitational-waves as a means of listening to highly relativistic dynamical
processes in astrophysics. This review discusses the promise of this field,
outlining why gravitational waves are worth pursuing, and what they are
uniquely suited to teach us about astrophysical phenomena. We review the
current state of the field, both theoretical and experimental, and then
highlight some aspects of gravitational-wave science that are particularly
exciting (at least to this author).


title: The Sub-Luminal Parsec-scale Jet of Mkn 501

abstract:
  We have combined Very Long Baseline Interferometry (VLBI) data from several
programs in order to resolve differences in reported parsec-scale jet speeds
for the TeV gamma-ray source Mkn501. Data from the VLBA 2cm survey, and 8 and
15 GHz data from the Radio Reference Frame Image Database, have been combined
with data from a 5 GHz VSOP Space VLBI observation to determine the apparent
motions of jet components in this source. The combined data set consists of 12
observations between April 1995 and July 1999. Four jet components are detected
at most epochs, all of which are clearly sub-luminal (i.e. with apparent speeds
< c), and two of which appear stationary. The established TeV gamma-ray sources
Mkn 501 and Mkn 421 thus both have sub-luminal parsec-scale jets, in contrast
to the apparently super-luminal jets of the majority of >100 MeV sources
detected by EGRET. No new VLBI component has emerged from the core following
the extended TeV high-state in 1997, again in contrast to the general behavior
of >100 MeV gamma-ray sources.


title: Microwave anisotropies from the Galactic halo

abstract:
  Models in which a large fraction of the Galactic dark matter takes the form
of cold gas clouds imply that there is thermal microwave emission from the
Galactic dark halo. Such models can therefore be directly constrained by data
on the microwave sky, and in particular the very sensitive observations of
microwave anisotropies which are now being made. To this end we have computed
the anisotropy power-spectrum expected for a Galactic dark halo made of cold,
dense gas clouds, including the effects of clustering with a CDM-like mass
spectrum of mini-halo substructure. The power-spectrum displays two peaks: one,
at l~50, is the Poisson noise for the mini-halos, and the second, much larger
and at much higher l, is the Poisson noise of the individual clouds. Because it
appears on small (milli-arcsecond) angular scales, where the instrumental
sensitivity is inevitably very poor, the latter signal is not directly
detectable. By contrast, clusters of cold gas clouds may contribute
significantly to the observed anisotropies if their emission has a grey-body
spectrum. In this case the peak fluctuation, at l~50, amounts to 4/|sin b|
micro-K in the Rayleigh-Jeans limit, and is the dominant Galactic foreground
between 40 and 80 GHz. It will be possible to constrain this foreground
component using low-latitude data from the MAP satellite, providing that its
spectrum conforms to a grey-body. If the spectrum is ``dusty'' there will be
relatively little power at frequencies below the thermal peak, and in this case
the predicted anisotropies are shown to be negligible.


title: Scaling Cosmology

abstract:
  We show that with the help of a suitable coupling between dark energy and
cold dark matter it is possible to reproduce any scaling solution $\rho
_{X}\propto \rho_{M}a^{\xi}$, where $\rho_{X}$ and $\rho_{M}$ are the densities
of dark energy and dark matter, respectively. We demonstrate how the case $\xi
= 1$ alleviates the coincidence problem. Future observations of supernovae at
high redshift as well as quasar pairs which are planned to discriminate between
different cosmological models will also provide direct constraints on the
coupling between dark matter and dark energy.


title: Cooling of superfluid neutron stars with muons

abstract:
  We extend our modeling of cooling of superfluid neutron stars by including
the production of muons in the core, in addition to neutrons, protons, and
electrons. The results are confronted with observations of middle-aged isolated
NSs. Muons have little effect on the hydrostatic structure of NSs, on the slow
cooling of low-mass NSs (RX J0822--43 and PSR 1055--52 in our model) and on the
rapid cooling of massive NSs. They affect, however, the moderately fast cooling
of medium-mass NSs (1E 1207--52, RX J0002+62, PSR 0656+14, Vela, and Geminga)
and shift appreciably the mass range of these NSs to lower masses, which is
important for correct interpretation of the observations. Moreover, the effects
of muons can accurately be reproduced by a simple renormalization of NS models
with no muons in the NS cores.


title: Are pulsar glitches triggered by a superfluid two-stream instability?

abstract:
  Mature neutron stars are expected to have several superfluid components.
Strong evidence for this is provided by the glitches that have been observed in
dozens of pulsars. The underlying idea behind most glitch models is that, as
the neutron star crust spins down due to the emission of electromagnetic
radiation, the superfluid component lags behind until a critical point is
reached and angular momentum is transferred from the superfluid to the crust,
leading to the spin-up associated with the glitch. In this Letter we describe a
superfluid analogue of the two-stream instability that is well known in plasma
physics, and provide evidence that this instability is likely to be relevant
for neutron stars. This is a new physical mechanism which may play a key role
in explaining the glitch mechanism and which could also prove to be relevant in
laboratory experiments on superfluid Helium.


title:
A Survey for Large Separation Lensed FIRST Quasars, II. Magnification
  Bias and Redshift Distribution

abstract:
  The statistics of large-separation gravitational lensing are a powerful tool
to probe mass distributions on the scale of galaxy clusters. In this paper we
refine the analysis of our survey for large-separation (>5'') lensed FIRST
quasars (Ofek et al. 2001) by estimating the magnification bias and the source
redshift distribution. Finding no large separation lens among 8000 likely
quasars in that sample, implies an upper bound on the lensed fraction of 3.7 x
10^-4 at 95% CL. From a published deep 1.4 GHz radio survey of the Hubble Deep
Field, and corresponding optical searches for faint quasars, we calculate a
lower limit to the `double flux magnification bias' affecting our
radio-optically selected sample, of B>1.1. From the four-colour information in
the SDSS Early Data Release, we calculate the photometric redshift distribution
of a sample of FIRST quasar candidates and compare it with the redshift
distribution from the FIRST Bright Quasar Survey. We find that the median
redshift of the quasars in our sample is about 1.4. With these new results, we
find that for all plausible cosmologies, the absence of lensed quasars in our
survey is consistent with a model based on an empirical, non-evolving, cluster
mass function, where clusters are represented by singular isothermal spheres.
On the other hand, comparison of our results to the lensing predictions of
published N-body-ray-tracing simulations (Wambsganss et al. 1995, 1998) rejects
the COBE normalised \Omega_{0}=1 CDM model at 99.9% confidence.


title: Numerical Simulations of the pulsed Jet of MWC 560

abstract:
  MWC 560 (= V694 Mon) is the only known Symbiotic Star system in which the jet
axis is practically parallel to the line of sight. Therefore this system is
predestinated to study the dynamical evolution and the propagation of stellar
jets. Spectroscopic monitoring done by Schmid et al. (2001) showed that the
outflow is seen as absorption features in the continuum of the accretion disk
and the accreting white dwarf, the emission line spectrum of the accretion disk
and the spectrum of the red giant. We present the first numerical simulations
of the jet of this particular object using the NIRVANA code (Ziegler & Yorke
1997) in order to reproduce the velocity structures seen in the observational
data. This code solves the equations of hydrodynamics and was modified to
calculate radiative losses due to non-equilibrium cooling by line-emission
(Thiele 2000).


title: Orbital and stellar parameters of symbiotic stars

abstract:
  This paper reviews current knowledge of symbiotic binaries, with special
emphasis on their multifrequency observational characteristics, and basic
parameters of the symbiotic system components. We start with a brief
presentation of variable phenomena found in symbiotic stars. This is followed
by a summary of the recent progress in determination of their orbital and
stellar parameters. We also discuss basic properties of the symbiotic giants
compared to single evolved giants as well as the nature of the hot component
and its outburst evolution.


title: The spectroscopic orbit and other parameters of AE Arae

abstract:
  We present an analysis of optical and near infrared spectra of the symbiotic
system AE Ara, composed of an M5.5 III giant similar to the Galactic Bulge M
giants and a hot luminous companion. In particular, we have determined for the
first time spectroscopic orbits based of the radial velocity curves for the red
and the hot component from the M-giant absorption lines and from the wings of
He II 4686 emission profiles, respectively. We have also studied spectral
changes and photometric variations in function of both the orbital phase and
activity. The resulting physical parameters of the binary components and the
nature of the hot component activity are briefly discussed.


title: Mm/submm observations of symbiotic binary stars

abstract:
  We present and discuss mm/submm observations of quiescent S-type symbiotic
systems, and compare them with popular models proposed to account for their
radio emission. We find that the M giant mass-loss rates derived from our
observations are systematically higher than those reported for single M giants.


title: Ellipsoidal variability of symbiotic giants

abstract:
  One of fundamental questions in relation to symbiotic binaries is the process
of mass transfer - Roche lobe overflow or stellar wind - and possibility of an
accretion disc formation. The presence of secondary minima in the quiescent
light curves of YY Her, CI Cyg and BF Cyg apparently due to ellipsoidal changes
of the red giant provides here important clues.


title: Comparing gas-phase and grain-catalyzed H2 formation

abstract:
  Because H2 formation on dust grain surfaces completely dominates gas-phase H2
formation in local molecular clouds, it is often assumed that gas-phase
formation is never important. In fact, it is the dominant mechanism in a number
of cases. In this paper, I briefly summarize the chemistry of gas-phase H2
formation, and show that it dominates for dust-to-gas ratios less than a
critical value D_cr. I also show that D_cr is simple to calculate for any given
astrophysical situation, and illustrate this with a number of examples, ranging
from H2 formation in warm atomic gas in the Milky Way to the formation of
protogalaxies at high redshift.


title:
Strong lensing constraints on the velocity dispersion and density
  profile of elliptical galaxies

abstract:
  We use the statistics of strong gravitational lensing from the CLASS survey
to impose constraints on the velocity dispersion and density profile of
elliptical galaxies. This approach differs from much recent work, where the
luminosity function, velocity dispersion and density profile were typically
{\it assumed} in order to constrain cosmological parameters. It is indeed
remarkable that observational cosmology has reached the point where we can
consider using cosmology to constrain astrophysics, rather than vice versa. We
use two different observables to obtain our constraints (total optical depth
and angular distributions of lensing events). In spite of the relatively poor
statistics and the uncertain identification of lenses in the survey, we obtain
interesting constraints on the velocity dispersion and density profiles of
elliptical galaxies. For example, assuming the SIS density profile and
marginalizing over other relevant parameters, we find 168 km/s < sigma_* < 200
km/s (68% CL), and 158 km/s < sigma_* < 220 km/s (95% CL). Furthermore, if we
instead assume a generalized NFW density profile and marginalize over other
parameters, the slope of the profile is constrained to be 1.50 < beta < 2.00
(95% CL). We also constrain the concentration parameter as a function of the
density profile slope in these models. These results are essentially
independent of the exact knowledge of cosmology. We briefly discuss the
possible impact on these constraints of allowing the galaxy luminosity function
to evolve with redshift, and also possible useful future directions for
exploration.


title: Linking Early and Late Type Galaxies to their Dark Matter Haloes

abstract:
  (Abridged) Using data from the 2dFGRS we compute the conditional luminosity
functions (CLFs) of early- and late-type galaxies. These functions give the
average number of galaxies with luminosity L that reside in a halo of mass M,
and are a powerful statistical tool to link the distribution of galaxies to
that of dark matter haloes. We find that the average mass-to-light ratios of
dark matter haloes have a minimum of about 100 Msun/Lsun around a halo mass of
about 3x10^{11} Msun. In addition, haloes with M < 10^{10} Msun are virtually
devoid of galaxies, while clusters have b_J band mass-to-light ratios in the
range 500-1000 Msun/Lsun. Finally, the fact that early-type galaxies are more
strongly clustered than late-type galaxies requires that the fraction of
late-type galaxies is a strongly declining function of halo mass. We also
compute two-point correlation functions as function of both luminosity and
galaxy type, and find a weak (strong) luminosity dependence for the late
(early) type galaxies. Finally we compare our CLFs with predictions from
several semi-analytical models for galaxy formation. As long as these models
accurately fit the 2dFGRS luminosity function the agreement with our
predictions is remarkably good. This indicates that we have recovered a
statistical description of how galaxies populate dark matter haloes which fits
nicely within the standard framework for galaxy formation.


title: A Compact Central Object in the Supernova Remnant Kes 79

abstract:
  A Chandra X-ray observation has detected an unresolved source at the center
of the supernova remnant Kes 79. The best single-model fit to the source
spectrum is a blackbody with an X-ray luminosity Lx (0.3-8.0 keV) = 7 x 10^{33}
ergs s^{-1}. There is no evidence for a surrounding pulsar wind nebula. There
are no cataloged counterparts at other wavelengths, but the absorption is high.
The source properties are similar to the central source in Cas A even though
the Kes 79 remnant is considerably older.


title:
Detecting X-ray filaments in the low redshift Universe with XEUS and
  Constellation-X

abstract:
  We propose a possible way to detect baryons at low redshifts from the
analysis of X-ray absorption spectra of bright AGN pairs. A simple
semi-analytical model to simulate the spectra is presented. We model the
diffuse warm-hot intergalactic medium (WHIM) component, responsible for the
X-ray absorption, using inputs from high-resolution hydro-dynamical simulations
and analytical prescriptions. We show that the number of OVII absorbers per
unit redshift with column density larger than $10^{13.5}$ cm$^{-2}$ -
corresponding to an equivalent width of $\sim$ 1 km/s - which will be possibly
detectable by {\it XEUS}, is $\magcir 30$ per unit redshift. {\it
Constellation-X} will detect $\sim 6$ OVII absorptions per unit redshift with
an equivalent width of 10 km/s. Our results show that, in a $\Lambda$CDM
Universe, the characteristic size of these absorbers at $z\sim 0.1$ is $\sim 1$
$h^{-1}$ Mpc. The filamentary structure of WHIM can be probed by finding
coincident absorption lines in the spectra of background AGN pairs. We estimate
that at least 20 AGN pairs at separation $\mincir 20$ arcmin are needed to
detect this filamentary structure at a 3$\sigma$ level. Assuming observations
of distant sources using {\it XEUS} for exposure times of 500 ksec, we find
that the minimum source flux to probe the filamentary structure is $\sim
2\times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$, in the 0.1-2.4 keV energy band. Thus,
most pairs of these extragalactic X-ray bright sources have already been
identified in the {\it ROSAT} All-Sky Survey. Re-observation of these objects
by future missions could be a powerful way to search for baryons in the low
redshift Universe.


title: Pulsation at the tip of the first giant branch?

abstract:
  The first results of our ongoing near-infrared (NIR) survey of the variable
red giants in the Large Magellanic Cloud, using the Infrared Survey Facility
(IRSF) and the SIRIUS infrared camera, are presented. Many very red stars were
detected and found that most of them are variables. In the observed
colour-magnitude diagram ($J-K, K$) and the stellar $K$ magnitude distribution,
the tip of the first giant branch (TRGB), where helium burning in the core
starts, is clearly seen. Apart from the genuine AGB variables, we found many
variable stars at luminosities around the TRGB. From this result, we infer that
a substantial fraction of them are RGB variables.


title: "Weather" Variability Of Close-in Extrasolar Giant Planets

abstract:
  Shallow-water numerical simulations show that the atmospheric circulation of
the close-in extrasolar giant planet (EGP) HD 209458b is characterized by
moving circumpolar vortices and few bands/jets (in contrast with ~10 bands/jets
and absence of polar vortices on cloud-top Jupiter and Saturn). The large
spatial scales of moving circulation structures on HD 209458b may generate
detectable variability of the planet's atmospheric signatures. In this Letter,
we generalize these results to other close-in EGPs, by noting that
shallow-water dynamics is essentially specified by the values of the Rossby
(Ro) and Burger (Bu) dimensionless numbers. The range of likely values of Ro (~
0.01 - 10) and Bu (~ 1 - 200) for the atmospheric flow of known close-in EGPs
indicates that their circulation should be qualitatively similar to that of HD
209458b. This results mostly from the slow rotation of these
tidally-synchronized planets.


title: BBN And CMB Constraints On Dark Energy

abstract:
  Current observational data favor cosmological models which differ from the
standard model due to the presence of some form of dark energy and, perhaps, by
additional contributions to the more familiar dark matter. Primordial
nucleosynthesis provides a window on the very early evolution of the universe
and constraints from Big Bang Nucleosynthesis (BBN) can bound the parameters of
models for dark matter/energy at redshifts of order ten billion. The spectrum
of temperature fluctuations imprinted on the Cosmic Microwave Background (CMB)
radiation opens a completely different window on the universe at epochs from
redshifts of order ten thousand to nearly the present. The CMB anisotropy
spectrum provides constraints on new physics which are independent of, and
complementary to those from BBN. Here we consider three classes of models for
the dark matter/energy: extra particles which were relativistic during the
early evolution of the universe (X); Quintessence models involving a
minimally-coupled scalar field (Q); models with a non-minimally coupled scalar
field which modify the strength of gravity during the early evolution of the
universe (G). We constrain the parameters of these models using data from BBN
and the CMB and identify the allowed regions in their parameter spaces
consistent with the more demanding joint BBN and CMB constraints. For X and Q
such consistency is relatively easy to find; it is more difficult for the G
models with an inverse power law potential for the scalar field.


title: A New Look at the Large-Scale HI Structure of the LMC

abstract:
  We present a Parkes multibeam \HI survey of the Large Magellanic Cloud (LMC).
This survey, which is sensitive to spatial structure in the range 200 pc to 10
kpc, complements the Australia Telescope Compact survey, which is sensitive to
structure in the range 15 pc to 500 pc. With an rms column density sensitivity
of 8 x 10^16/cm^2 for narrow lines and 4 x 10^17/cm^2 for typical linewidths of
40 km/s, emission is found to be extensive well beyond the main body of the
LMC. Arm-like features extend from the LMC to join the Magellanic Bridge and
the Leading Arm, a forward counterpart to the Magellanic Stream. These
features, whilst not as dramatic as those in the SMC, appear to have a common
origin in the Galactic tidal field, in agreement with recent 2MASS and DENIS
results for the stellar population. The diffuse gas which surrounds the LMC,
particularly at pa's 90 to 330 deg, appears to be loosely associated with tidal
features, but loosening by the ram pressure of tenuous Galactic halo gas
against the outer parts of the LMC cannot be discounted. High-velocity clouds,
which lie between the Galaxy and the LMC in velocity and which appear in the UV
spectra of some LMC stars, are found to be associated with the LMC if their
heliocentric velocity exceeds about +100 km/s. They are possibly the product of
energetic outflows from the LMC disk. The HI mass of the LMC is found to be
(4.8+/-0.2) x 10^8 Msun (for an assumed distance of 50 kpc), substantially more
than previous recent measurements.


title:
Supernova relic neutrinos and observational implications for neutrino
  oscillation

abstract:
  We investigate the flux of supernova relic neutrinos (SRN) for several
neutrino oscillation models with parameters inferred from recent experimental
results. In the calculation, we adopt the realistic {\it time-dependent}
supernova density profile, which is very different from the static progenitor
profile owing to shock propagation. The Earth matter effect is also included
appropriately using realistic density profile of the Earth. As a result, these
two effects are found to induce the flux difference by a few % in the detection
energy range ($E_\nu > 19.3$ MeV). We also set 90% C.L. upper limit on SRN flux
for various oscillation models using the recently released observational result
by Super-Kamiokande (SK). In the near future, further reduced upper limit is
actually expected, when the current SK data are reanalyzed using some technique
to reduce background events against SRN signals. It is expected that the
reduced upper limit is sufficient to provide useful implications for neutrino
oscillation.


title:
HST images of B2 radio galaxies: a link between circum-nuclear dust and
  radio properties?

abstract:
  Almost 60% of the B2 low luminosity radio galaxies have been observed with
the Hubble Space Telescope. We present an analysis of the dust features, which
are often present in the form of circum-nuclear disks or lanes, and show that
there are correlations between radio source and dust properties. It is found
that nearby radio sources in which a jet has been detected tend to have dust
more often than sources without jets; the dust is often in the form of disks or
lanes. Moreover the radio jets are close to perpendicular to the disk or lane
in the weaker radio sources (with P < 10^{24} W/Hz). In stronger sources the
orientation effect appears to be weak or even absent. Also the dust masses
found in the weaker radio sources are smaller than in the stronger ones (log
M/M_sun ~ 3 against 5 respectively). More generally it appears that there is a
correlation between dust mass and total radio power (for those sources in which
dust has been detected); we show that this correlation is not induced by
redshift.


title: B0850+054: a new gravitational lens system from CLASS

abstract:
  We report the discovery of a new gravitational lens system from the CLASS
survey. Radio observations with the VLA, the WSRT and MERLIN show that the
radio source B0850+054 is comprised of two compact components with identical
spectra, a separation of 0.7 arcsec and a flux density ratio of 6:1. VLBA
observations at 5 GHz reveal structures that are consistent with the
gravitational lens hypothesis. The brighter of the two images is resolved into
a linear string of at least six sub-components whilst the weaker image is
radially stretched towards the lens galaxy. UKIRT K-band imaging detects an
18.7 mag extended object, but the resolution of the observations is not
sufficient to resolve the lensed images and the lens galaxy. Mass modelling has
not been possible with the present data and the acquisition of high-resolution
optical data is a priority for this system.


title: Evolution of the symbiotic nova RX Puppis

abstract:
  We present and discuss a hundred year history of activity of the hot
component of RX Pup based on optical photometry and spectroscopy. The outburst
evolution of RX Pup resembles that of other symbiotic novae whereas at
quiescence the hot component shows activity (high and low activity states)
resembling that of symbiotic recurrent novae T CrB and RS Oph.


title: The mass of the neutron star in the low-mass X-ray binary 2A 1822-371

abstract:
  Using phase resolved spectroscopic observations obtained with the Ultraviolet
and Visual Echelle Spectrograph on ESO's Kueyen Very Large Telescope
supplemented by spectroscopic observations obtained with the Boller and Chivens
Spectrograph on the Walter Baade Magellan telescope, we found sinusoidal
radial-velocity variations with a semi-amplitude 327+-17 km/s. From previous
observations and from the fact that the epoch of minimum velocity arrived early
with respect to the epoch calculated from pulse timing we know that the
companion star is suffering from irradiation. Since we most likely observed
primarily the side of the companion star facing the observer at phase ~0.75 the
velocity quoted above is not the true radial velocity semi-amplitude of the
companion star. Assuming a uniform contribution to the line profile from this
hemisphere yields a radial velocity semi-amplitude of 280+-26 km/s for a
systemic velocity of 54+-24 km/s; if the contribution is instead weighted
somewhat more towards the side of the companion facing the X-ray source then
the true semi-amplitude is larger than this value. Together with the well
constrained inclination (81<i<84 degrees) and the mass-function determined from
pulse-timing analysis (2.03+-0.03 x 10^-2 Msun), we derive a lower limit to the
mass of the neutron star and to that of the companion star of 0.97+-0.24 Msun
and 0.33+-0.05 Msun, respectively (1 sigma; including uncertainties in the
inclination). We briefly discuss other aspects of the spectrum and the
implications of our findings.


title:
Non-Gaussian Tails of Cosmological Density Distribution Function from
  Dark Halo Approach

abstract:
  We present a simple model based on the dark halo approach which provides a
useful way to understand key points determining the shape of the non-Gaussian
tails of the dark matter one-point probability distribution function(PDF). In
particular, using the scale-free models with power-law profile of dark halos,
we derive a simple analytic expression for the one-point PDF. It is found that
the shape of the PDF changes at the characteristic value of $\delta_*$ which is
defined by the smoothed density of a halo with the characteristic mass $M_*$ at
the epoch. In cold dark matter models with top-hat smoothing filters, the
characteristic smoothed density at present time typically takes the value
$\delta_*\gg 1$ for a small smoothing scale $\rth\sim 1$Mpc$/h$ and conversely
$\delta_*\ll 1$ for a large smoothing scale $\rth > 10$Mpc$/h$. On the range
$\delta/\delta_*<1$, the shape of the PDF is almost solely determined by the
outer slope of halos and scales as a power-law. The resultant non-Gaussian
tails of PDF then resemble the log-normal PDFs in that range and show a good
agreement with N-body simulations, which can be ascribed to the universality of
the outer slope of the halo profile. In contrast, tails of one-point PDF in the
range $\delta/\delta_*>1$ basically follow the steep exponential tails of the
halo mass function, which exhibit a strong sensitivity to both the outer slope
of the halo profile and the initial power spectrum. Based on these results, the
discussion on the PDF of galaxy distribution and the application to the weak
lensing statistics are also presented.


title:
The Mass of the Milky Way: Limits from a Newly Assembled Set of Halo
  Objects

abstract:
  We set new limits on the mass of the Milky Way, making use of the latest
kinematic information for Galactic satellites and halo objects. In order to
bind these sample objects to the Galaxy, their rest-frame velocities must be
lower than their escape velocities at their estimated distances. This
constraint enables us to show that the mass estimate of the Galaxy is largely
affected by several high-velocity objects (Leo I, Pal 3, Draco, and a few FHB
stars), not by a single object alone (such as Leo I), as has often been the
case in past analyses. We also find that a gravitational potential that gives
rise to a declining rotation curve is insufficient to bind many of our sample
objects to the Galaxy; a possible lower limit on the mass of the Galaxy is
about 2.2 x 10^12 Msolar. To be more quantitative, we adopt a Bayesian
likelihood approach to reproduce the observed distribution of the current
positions and motions of the sample, in a prescribed Galactic potential that
yields a flat rotation curve. This method enables a search for the most likely
total mass of the Galaxy, without undue influence in the final result arising
from the presence or absence of Leo I, provided that both radial velocities and
proper motions are used. The most likely total mass derived from this method is
2.5^+0.5_-1.0 x 10^12 Msolar (including Leo I), and 1.8^+0.4_-0.7 x 10^12
Msolar (excluding Leo I).


title:
Evolution of Elliptical Galaxies at z >~ 1 Revealed from a Large,
  Multicolor Sample of Extremely Red Objects

abstract:
  We study the evolution of elliptical galaxies at z >~ 1 on the basis of a
sample of 247 Extremely Red Objects (EROs) with R-Ks >= 3.35 (AB) and Ks <=
22.1 (AB) constructed from BVRi'z'JHKs multicolor data of a 114 arcmin2 area in
the Subaru/XMM Deep Survey Field. By fitting template spectra of old
ellipticals (OEs) and young, dusty starbursts (DSs) to the multicolor data, we
classify EROs into these two classes and estimate their redshifts. We find that
58% of the EROs in our sample belong to the OE class and that 24% of the OEs
are fit by a spectrum having a disk component with the B-band bulge-to-total
luminosity ratio of <= 0.9. We compare the observed surface density of OEs with
predictions from passive evolution models. We then derive rest-frame B-band
luminosity functions (LFs) of OEs in our sample at z=1-1.5 and 1.5-2.5. We find
that the LF at z=1-1.5 roughly agrees with the LF of local ellipticals if a
dimming of 1.3 mag from z=1.25 to the present epoch is assumed. On the other
hand, the amplitude of the LF at z=1.5-2.5 is found to be lower than that of
the local LF by a factor of ~ 3 over the whole range of magnitude observed.
Taking account of a strong decrease in the number density of morphologically
classified early-type galaxies at z >~ 1.5 found by several authors, we
conclude that the majority of ellipticals seen at present have not established
either a red color or a smooth 1/4-law profile before z ~ 1.5$. (abridged)


title:
Optical observations of a newly identified compact galaxy group near the
  Zone of Avoidance

abstract:
  We have identified a new group of galaxies, CG J0247+44.9, at low Galactic
latitude (l=143.64 deg, b=-13.29 deg), which satisfies Hickson's criteria
(Hickson 1997) for Compact Groups (CGs). Our group consists of six members, two
of which are in close interaction (IRAS 02443+4437). We present here optical
photometry (BVRI) and low resolution spectroscopy of the individual galaxies
and investigate the global properties of the group. Our morphological analysis
reveals that two out of the six objects are lenticular galaxies. The others are
spirals showing emission lines in their spectra through which we could classify
them as a starburst galaxy (the spiral member of the IRAS 02443+4437 close
pair), a Seyfert 2, a LINER and a weak H II galaxy. Since the S0/Sa is the
prevailing morphology for the galaxies of this group, which is also
characterized by a short crossing time and a relatively high velocity
dispersion, we suggest that CG J0247+44.9 is a dynamically old compact group.


title:
SkyDOT (Sky Database for Objects in the Time Domain): A Virtual
  Observatory for Variability Studies at LANL

abstract:
  The mining of Virtual Observatories (VOs) is becoming a powerful new method
for discovery in astronomy. Here we report on the development of SkyDOT (Sky
Database for Objects in the Time domain), a new Virtual Observatory, which is
dedicated to the study of sky variability. The site will confederate a number
of massive variability surveys and enable exploration of the time domain in
astronomy. We discuss the architecture of the database and the functionality of
the user interface. An important aspect of SkyDOT is that it is continuously
updated in near real time so that users can access new observations in a timely
manner. The site will also utilize high level machine learning tools that will
allow sophisticated mining of the archive. Another key feature is the real time
data stream provided by RAPTOR (RAPid Telescopes for Optical Response), a new
sky monitoring experiment under construction at Los Alamos National Laboratory
(LANL).


title: Charge ratio of muons from atmospheric neutrinos

abstract:
  We calculate the intensities and angular distributions of positive and
negative muons produced by atmospheric neutrinos. We comment on some sources of
uncertainty in the charge ratio. We also draw attention to a potentially
interesting signature of neutrino oscillations in the muon charge ratio, and we
discuss the prospects for its observation (which are not quite within the reach
of currently planned magnetized detectors).


title:
Discovery of Cyclotron Resonance Features in the Soft Gamma Repeater SGR
  1806-20

abstract:
  We report evidence of cyclotron resonance features from the Soft Gamma
Repeater SGR 1806-20 in outburst, detected with the Rossi X-ray Timing Explorer
in the spectrum of a long, complex precursor that preceded a strong burst. The
features consist of a narrow 5.0 keV absorption line with modulation near its
second and third harmonics (at 11.2 keV and 17.5 keV respectively). The line
features are transient and are detected in the harder part of the precursor.
The 5.0 keV feature is strong, with an equivalent width of ~ 500 eV and a
narrow width of less than 0.4 keV. Interpreting the features as electron
cyclotron lines in the context of accretion models leads to a large mass-radius
ratio (M/R > 0.3 M_sun/km) that is inconsistent with neutron stars or that
requires a low (5-7)x10^{11} G magnetic field that is unlikely for SGRs. The
line widths are also narrow compared with those of electron cyclotron
resonances observed so far in X-ray pulsars. In the magnetar picture, the
features are plausibly explained as ion cyclotron resonances in an ultra-strong
magnetic field that have recently been predicted from magnetar candidates. In
this view, the 5.0 keV feature is consistent with a proton cyclotron
fundamental whose energy and width are close to model predictions. The line
energy would correspond to a surface magnetic field of 1.0x10^{15} G for SGR
1806-20, in good agreement with that inferred from the spin-down measure in the
source.


title: X-ray, Ly-alpha and H-alpha Emission from Simulated Disk Galaxies

abstract:
  The X-ray properties of the haloes of disk galaxies formed in fully
cosmological, hydro/gravity simulations are discussed. The results are found to
be consistent with observational X-ray detections and upper limits. Disk galaxy
haloes are predicted to be about an order of magnitude brighter in soft X-rays
at z~1 than at z=0. The Ly-alpha and H-alpha surface brightness of an edge-on,
Milky Way like model galaxy has been determined. The emission is found to be
quite extended, with a scale height of about 600 pc, neglecting extinction
corrections.


title:
New Evidence for Proton Cyclotron Resonance in a Magnetar Strength Field
  from SGR 1806-20

abstract:
  A great deal of evidence has recently been gathered in favor of the picture
that Soft Gamma Repeaters and Anomalous X-Ray Pulsars are powered by
ultra-strong magnetic fields (B > 10^{14} G; i.e. magnetars). Nevertheless,
present determination of the magnetic field in such magnetar candidates has
been indirect and model dependent. A key prediction concerning magnetars is the
detection of ion cyclotron resonance features, which would offer a decisive
diagnostic of the field strength. Here we present the detection of a 5 keV
absorption feature in a variety of bursts from the Soft Gamma Repeater SGR
1806-20, confirming our initial discovery (Ibrahim et al. 2002) and
establishing the presence of the feature in the source's burst spectra. The
line feature is well explained as proton cyclotron resonance in an ultra-strong
magnetic field, offering a direct measurement of SGR 1806-20's magnetic field
(B ~ 10^{15} G) and a clear evidence of a magnetar. Together with the source's
spin-down rate, the feature also provides the first measurement of the
gravitational redshift, mass and radius of a magnetar.


title:
Rotational mixing in low-mass stars : I Effect of the mu-gradients in
  main sequence and subgiant Pop I stars

abstract:
  We present a first set of results concerning stellar evolution of rotating
low-mass stars. Our models include fully consistent transport of angular
momentum and chemicals due to the combined action of rotation induced mixing
(according to Maeder & Zahn 1998) and element segregation. The analysis of the
effects of local variations of molecular weight due to the meridional
circulation on the transport of angular momentum and chemicals are under the
scope of this study. We apply this mechanism to low mass main sequence and
subgiant stars of population I. We show that the so-called $\mu$-currents are
of major importance in setting the shape of the rotation profile, specially
near the core. Furthermore, as shown by Talon & Charbonnel (1998) and
Charbonnel & Talon (1999) using models without $\mu$-currents, we confirm that
rotation-induced mixing in stars braked via magnetic torquing can explain the
blue side of the Li dip, as well as the low Li abundances observed in subgiants
even when $\mu$-currents are taken into account. We emphasize that $\mu$
variations are not to be neglected when treating rotation-induced mixing, and
that they could be of great importance for latter evolutionary stages.


title:
Tracing the power-law component in the energy spectrum of black hole
  candidates as a function of the QPO frequency

abstract:
  We investigated the relation between the centroid frequency of the
quasi-periodic oscillation observed in the power density spectra of a sample of
galactic black-hole candidates with the power-law photon index obtained from
spectral fits. Our aim is to avoid inner accretion disk radius determination
directly from spectral fits, given the uncertainties of the absolute values
obtained in that way, but to base our analysis on the likely association of QPO
frequency to a characteristic radius. We used archival RXTE data of GRS
1915+105 and published parameters for GRO 1655-40, XTE J1550-564, XTE J1748-288
and 4U 1630-47. While for low values of the QPO frequency, the two parameters
are clearly correlated for each source, there is evidence for a turnoff in the
correlation above a characteristic frequency, different for different sources.
We discuss the possible nature of this turnoff.


title: A Numerical Method for General Relativistic Magnetohydrodynamics

abstract:
  This paper describes the development and testing of a general relativistic
magnetohydrodynamic (GRMHD) code to study ideal MHD in the fixed background of
a Kerr black hole. The code is a direct extension of the hydrodynamic code of
Hawley, Smarr, and Wilson, and uses Evans and Hawley constrained transport (CT)
to evolve the magnetic fields. Two categories of test cases were undertaken. A
one dimensional version of the code (Minkowski metric) was used to verify code
performance in the special relativistic limit. The tests include Alfv\'en wave
propagation, fast and slow magnetosonic shocks, rarefaction waves, and both
relativistic and non-relativistic shock tubes. A series of one- and
two-dimensional tests were also carried out in the Kerr metric: magnetized
Bondi inflow, a magnetized inflow test due to Gammie, and two-dimensional
magnetized constant-$l$ tori that are subject to the magnetorotational
instability.


title:
VLA Observations of the "Eye of the Tornado"- the High Velocity \HII
  Region G357.63-0.06

abstract:
  The unusual supernova remnant candidate G357.7-0.1 and the compact source
G357.63-0.06 have been observed with the Very Large Array at 1.4 and 8.3 GHz.
The H92$\alpha$ line (8.3 GHz) was detected from the compact source with a
surprising velocity of about -210 km/s indicating that this source is an \HII
region, is most likely located at the Galactic center, and is unrelated to the
SNR. The \HI absorption line (1.4 GHz) data toward these sources supports this
picture and suggests that G357.7-0.1 lies farther away than the Galactic
center.


title: Young Circumstellar Disks and Their Evolution: A Review

abstract:
  A detailed understanding of the physics of star and planet formation requires
study of individual objects as well as statistical assessment of global
properties and evolutionary trends. Observational investigations of
circumstellar material surrounding young stars have matured to the point that
both spectral energy distributions sampled over more than four decades in
wavelength and spatially resolved images or interferometric visibilities at
limited optical/infrared and sub-/millimeter wavelengths are becoming
available, though for few individual objects at present. Data on star/disk
systems combined with continuing surveys for exo-solar planets themselves will
lead to constraints on the likelihood and frequency of solar system formation.
An overarching goal of these pursuits is to connect what is observed elsewhere
with the history of our own solar solar system, and hence enhance our
appreciation of the uniqueness -- or lack thereof -- of the human circumstance.


title:
Recent Breakthroughs in Detecting Neutron Star Binaries in Globular
  Clusters

abstract:
  Binary stars have long been considered to play a crucial role in globular
cluster evolution, and offer the advantages of studying systems at the same,
well-determined distances. However, early search attempts were consistently
thwarted by crowding (particularly in the optical) and initial detections were
limited to small numbers of low-mass X-ray binaries (LMXBs) and a handful of
other systems. This resolution hurdle has been dramatically overcome by the
superb spatial resolution and sensitivity of HST and Chandra (supported by
advances in radio observations), enabling the detection in individual clusters
of more than 10, and in some cases more than 100, binaries. This review will
focus on detections of neutron star binaries, including recent optical
identifications, the exciting discoveries of multiple LMXBs in quiescence (with
the potential to constrain neutron star equations of state) and the detections
of millisecond pulsars (MSPs) in X-ray and optical images.


title: Nuclear Composition of Gamma-Ray Burst Fireballs

abstract:
  We study three processes that shape the nuclear composition of GRB fireballs:
(1) neutronization in the central engine, (2) nucleosynthesis in the fireball
as it expands and cools, and (3) spallation of nuclei in subsequent internal
shocks. The fireballs are found to have a neutron excess and a marginally
successful nucleosynthesis. They are composed of free nucleons,
alpha-particles, and deuterium. A robust result is the survival of a
significant neutron component, which has important implications. First, as
shown in previous works, neutrons can lead to observable multi-GeV neutrino
emission. Second, as we show in an accompanying paper, neutrons impact the
explosion dynamics at radii up to 10^{17} cm and change the mechanism of the
GRB afterglow emission.


title: A Survey for Circumstellar Disks Around Young Substellar Objects

abstract:
  (Abridged) We have completed the first systematic survey for disks around
spectroscopically identified young brown dwarfs and very low mass stars. We
have obtained L'-band (3.8 um) imaging for 38 very cool objects in IC 348 and
Taurus. Our targets span spectral types from M6 to M9.5 (~100 to ~15 Mjup).
Using the objects' measured spectral types and extinctions, we find that most
of our sample (77%+/-15%) possess intrinsic IR excesses, indicative of disks.
Because the excesses are modest, conventional analyses using only IR colors
would have missed most of the sources with excesses. The observed IR excesses
are correlated with Halpha emission, consistent with a common accretion disk
origin. The excesses can be explained by disk reprocessing of starlight alone;
the implied accretion rates are at least an order of magnitude below typical
values for classical T Tauri stars. The observed distribution of IR excesses
suggests the presence of inner disk holes. The disk frequency appears to be
independent of the mass and age. In the same star-forming regions, disks around
brown dwarfs are at least as long-lived (~3 Myr) as disks around the T Tauri
stars. Altogether, the frequency and properties of young circumstellar disks
appear to be similar from the stellar regime down to the substellar and
planetary-mass regime. This provides prima facie evidence of a common origin
for most stars and brown dwarfs.


title:
Flaring up: radio diagnostics of the kinematic, hydrodynamic and
  environmental properties of GRBs

abstract:
  The specific incidence of radio flares appears to be significantly larger
than that of the prompt optical emission. This abundance, coupled with the
reverse shock interpretation suggests that radio flares add a unique probe on
the physics of GRB shocks. Motivated thus, we estimate the strength of the
reverse shock expected for bursts in which multi-wavelength observations have
allowed the physical parameters of the forward shock to be determined. We use
all 6 bursts (980519, 990123, 990510, 991208, 991216, 000418) which are found
to be adiabatic and thus predicted to have a strong reverse shock. We aim to
constrain the hydrodynamic evolution of the reverse shock and the initial bulk
Lorentz factor -- which we found to be between $10^{2}$ and $10^{3}$ and well
above the lower limits derived from the requirement that gamma-ray bursts be
optically thin to high-energy photons. In half of the cases we improve the
description of the early afterglow lightcurves by adding a contribution from
the reverse shock. Modelling of this early emission provides the opportunity to
investigate the immediate surroundings of the burst. For 991216 and 991208, the
expected $1/r^2$ density structure for a stellar wind is not compatible with
the early afterglow lightcurves. Considering the radial range relevant to these
GRBs, we discuss the conditions under which the inclusion of a wind termination
shock may resolve the absence of a $1/r^2$ density profile.


title: Dynamical consequences of CDM merger trees

abstract:
  Within the context of the standard structure formation scenario, massive
present day elliptical galaxies are sometimes thought of as the result of a
major merger of spiral systems. Through extensive SPH simulations of merging
spirals, we have explored these processes with the aim of quantifying their
relaxation times. This is important, as it sets a minimum time interval between
the onset of a merger, and the appearance of an elliptical galaxy. We then
compare this constraint with predictions of the hierarchical scenario, computed
through Press-Schechter merger trees. We find evidence for elliptical systems
which appear not to have been formed by a major merger of spirals.


title: What future does the universe have?

abstract:
  We discuss the future evolution of the universe in the light of recent
observations. The apparent luminosity vs. redshift of supernovae favor an
accelerating universe. However an Einstein-de Sitter critical universe should
not be ruled out yet.


title: Cosmic Inflation and the Arrow of Time

abstract:
  Cosmic inflation claims to make the initial conditions of the standard big
bang "generic". But Boltzmann taught us that the thermodynamic arrow of time
arises from very non-generic ("low entropy") initial conditions. I discuss how
to reconcile these perspectives. The resulting insights give an interesting way
to understand inflation and also compare inflation with other ideas that claim
to offer alternative theories of initial conditions.


title: Forming Globular Cluster Systems in a Semi-analytic Scheme

abstract:
  We apply the semi-analytical galaxy formation code of Cole et al. to
investigate the formation of globular cluster (GC) systems in hierarchical
clustering scenarios. The nature of the model allows us to investigate the
properties of GC systems and their parent galaxies within a cosmological
framework, over a wide dynamic range of mass and time resolution. Assuming GCs
form during mergers of gaseous systems, the metal-rich peak of the classical
'bimodal' metallicity distribution of GCs naturally falls out of our model,
where such merging occurs over a wide range of redshifts. The physical origin
of old, metal-poor GCs (the metal-poor peak) is harder to understand, since
their formation must be decoupled from the ongoing star formation in these
systems at high redshift (z~5). Within the context of semi-analytic models in
general, a possible solution lies in a cut-off in the GC formation efficiency
at a characteristic local star formation rate.


title: The Molecular Disk in the Cloverleaf Quasar

abstract:
  We propose a new interpretation for the CO emitting region of the Cloverleaf
(H1413+1143), a gravitationally lensed QSO. We fit a two-galaxy lensing model
directly to the IRAM CO(7-6) data rather than to the optical HST image and from
the fit we infer that the CO(7-6) source is a disk-like structure with a
characteristic radius of $785 {\rm pc} (in the currently widely accepted
cosmology: cosmological constant $\Omega_{\Lambda}=0.7$, matter content
$\Omega_{m}=0.3$, and Hubble constant $H_{0}=65 {\rm km s^{-1} mpc}^{-1}$), a
size similar to that of the CO emitting regions present in nearby starburst
ultraluminous infrared galaxies. We therefore suggest that the Cloverleaf
contains both an extended rotating molecular starburst disk and a central
quasar.


title: Near infra-red spectroscopy of V838 Monocerotis

abstract:
  Near IR, multi-epoch, spectroscopic and photometric observations of the
enigmatic, eruptive variable V838 Mon in JHK bands are reported. One of the
unusual features is the detection of several strong neutral TiI lines in
emission in the K band. From the strength of these lines, the mass of the
ejected envelope is estimated to be in the range 10e-7 to 10e-5 M(sun). The
spectra also show the strong presence of the first and second overtones of 12CO
bands seen in the K and H bands. The CO bands show a complex evolution. Deep
water bands at 1.4 and 1.9 micron are also seen later in the object's
evolution. Blackbody fits to the JHK photometric data show that V838 Mon has
evolved to temperatures between 2400 - 2600 K by approximately 130 days after
outburst. The spectra at this stage have the general characteristics of a very
cool M giant.


title:
Does the fine structure constant vary? A third quasar absorption sample
  consistent with varying alpha

abstract:
  We report preliminary results from a third sample of quasar absorption line
spectra from the Keck telescope which has been studied to search for any
possible variation of the fine structure constant, alpha. This third sample,
which is larger than the sum of the two previously published samples, shows the
same effect, and also gives, as do the previous two samples, a significant
result. The combined sample yields a highly significant effect, da/a = (alpha_z
- alpha_0)/alpha_0 = -0.57 +/- 0.10 x 10^{-5}, averaged over the redshift range
0.2 < z < 3.7. We include a brief discussion of small-scale kinematic structure
in quasar absorbing clouds. However, kinematics are unlikely to impact
significantly on the averaged non-zero da/a above, and we have so far been
unable to identify any systematic effect which can explain it. New measurements
of quasar spectra obtained using independent instrumentation and telescopes are
required to properly check the Keck results.


title:
Does the fine structure constant vary? A detailed investigation into
  systematic effects

abstract:
  We have previously presented 5.7-sigma evidence for a smaller alpha at
redshifts 0.2 < z_abs < 3.7 from a sample of 128 Keck/HIRES quasar absorption
systems: da/a = (-0.57 +/- 0.10) x 10^{-5}. A non-zero da/a manifests itself as
a distinct pattern of shifts in the measured absorption line wavelengths. The
statistical error is now small: we do detect small line shifts in the HIRES
data. Whether these shifts are due to systematic errors or due to real
variation in alpha is now the central question. Here we summarize the two
potentially most important systematic effects: atmospheric dispersion and
isotopic abundance evolution. Previously, these have been difficult to
quantify/model but here we find that neither of them can explain our results.
Furthermore, the HIRES spectra themselves contain no evidence for these
effects. Independent measurements of da/a with a different telescope and
spectrograph are now crucial if we are to rule out or confirm the present
evidence for a variable alpha.


title: Quintessence and the accelerating universe

abstract:
  Observations seem to indicate that our universe is presently accelerating due
to the presence of dark energy. Quintessence represents a possible way to model
the dark energy. In these proceedings, we briefly review its main properties.


title: Light Echoes in Type Ia Supernovae

abstract:
  Light echoes are a promising tool to probe the environment where SNe Ia
explode and an independent source of information on the progenitor's nature.
After giving a brief introduction to the phenomenon we review the two known
cases, i.e. SNe 1991T and 1998bu. We then present the results we obtained from
the test case of SN1998es in NGC632. This object was classified as a 1991T-like
event and was affected by a strong reddening, a fact which made it a good
candidate for a light echo detection.


title: Chemically Consistent Evolutionary Synthesis

abstract:
  To account for the range of stellar metallicities in local galaxies and for
the increasing importance of low metallicities at higher redshift we present
chemically consistent models for the spectral and chemical evolution of
galaxies over cosmological timescales. We discuss advantages, limitations and
future prospects of our approach.


title:
The wavelength dependence of Sgr A* size and the unified model of
  compact radio sources

abstract:
  Using, in particular, the data upon Sgr A*, we propose the unified model of
compact radio sources, i.e. of pulsars, maser sources, and active galactic
nuclei. The unification is based on the wavelength dependence of radio source
size. It is shown that the compact sources are characterized by a maser
amplification of thermal radio emission. The density, temperature, and magnetic
field profiles of compact sources are discussed. The wavelength dependence of
Sgr A* size is explained by the effect of the gravitational field of a central
energy source on a gas flow.


title: Fusion rate enhancement due to energy spread of colliding nuclei

abstract:
  Experimental results for sub-barrier nuclear fusion reactions show cross
section enhancements with respect to bare nuclei which are generally larger
than those expected according to electron screening calculations. We point out
that energy spread of target or projectile nuclei is a mechanism which
generally provides fusion enhancement. We present a general formula for
calculating the enhancement factor and we provide quantitative estimate for
effects due to thermal motion, vibrations inside atomic, molecular or crystal
system, and due to finite beam energy width. All these effects are marginal at
the energies which are presently measurable, however they have to be considered
in future experiments at still lower energies. This study allows to exclude
several effects as possible explanation of the observed anomalous fusion
enhancements, which remain a mistery.


title: Quasi-Periodic X-ray Oscillations in the Source Sco X-1

abstract:
  The RXTE observations of Scorpius X-1 in 1996-1999 are presented. The
properties of its quasi-periodic X-ray oscillations are studied in detail. The
results obtained are used for analysis in terms of the transition-layer model
(TLM) and the relativistic-precession model (RPM) for a slowly rotating neutron
star. Theoretical predictions of the two models are compared and their
self-consistency is verified. The tilt of the magnetosphere to the
accretion-disk plane, the neutron-star mass, and its angular momentum are
determined in the model frameworks.


title:
Quasar Tomography: Unification of Echo Mapping and Photoionisation
  Models

abstract:
  Reverberation mapping uses time-delayed variations in photoionised emission
lines to map the geometry and kinematics of emission-line gas in active
galactic nuclei. In previous work, the light travel time delay
tau=R(1+cos(theta))/c and Doppler shift v give a 2-d map Psi(tau,v) for each
emission line. Here we combine the velocity-delay information with
photoionisation physics in a maximum entropy fit to the full reverberating
spectrum F_lam(lam,t) to recover a 5-d map of the differential covering
fraction f(R,theta,n,N,v), with n and N the density and column density of the
gas clouds. We test the method for a variety of geometries (shells, rings,
disks, clouds, jets) by recovering a 3-d map f(R,theta,n) from reverberations
in 7 uv emission lines. The best test recovers a hollow shell geometry,
defining R to 0.15 dex, n to 0.3 dex, and ionisation parameter U ~ 1/(n R^2) to
0.1 dex. The results are sensitive to the adopted distance and luminosity,
suggesting that these parameters may be measurable as well.


title: What determines galactic evolution?

abstract:
  We are briefly introducing the most important ingredients to study galactic
evolution. In particular the roles of star formation, nucleosynthesis and gas
flows. Then we are discussing the two different approaches to galactic
evolution: the stellar population approach (chemical evolution models) and the
hierarchical clustering scenario for galaxy formation. It is shown that there
are still some controversial points in the two approaches, as evident in the
brief summary of the discussion.


title: Local Magnetohydrodynamical Models of Layered Accretion Disks

abstract:
  Using numerical MHD simulations, we have studied the evolution of the
magnetorotational instability in stratified accretion disks in which the
ionization fraction (and therefore resistivity) varies substantially with
height. This model is appropriate to dense, cold disks around protostars or
dwarf nova systems which are ionized by external irradiation of cosmic rays or
high-energy photons. We find the growth and saturation of the MRI occurs only
in the upper layers of the disk where the magnetic Reynolds number exceeds a
critical value; in the midplane the disk remains queiscent. The vertical
Poynting flux into the "dead", central zone is small, however velocity
fluctuations in the dead zone driven by the turbulence in the active layers
generate a significant Reynolds stress in the midplane. When normalized by the
thermal pressure, the Reynolds stress in the midplane never drops below about
10% of the value of the Maxwell stress in the active layers, even though the
Maxwell stress in the dead zone may be orders of magnitude smaller than this.
Significant mass mixing occurs between the dead zone and active layers.
Fluctuations in the magnetic energy in the active layers can drive vertical
oscillations of the disk in models where the ratio of the column density in the
dead zone to that in the active layers is <10. These results have important
implications for the global evolution of a layered disk, in particular there
may be residual mass inflow in the dead layer. We discuss the effects that dust
in the disk may have on our results.


title: Chemical evolution of Elliptical Galaxies and the ICM

abstract:
  We present a new model for the chemical evolution of elliptical galaxies
taking into account SN feedback, detailed nucleosynthesis and galactic winds.
We discuss the effect of galactic winds on the chemical enrichment of the ICM
and compute the energy per particle injected by the galaxies into the ICM.


title: An optical bow shock around the nearby millisecond pulsar J2124-3358

abstract:
  We report the discovery of an H-alpha-emitting bow-shock nebula powered by
the nearby millisecond pulsar J2124-3358. The bow shock is very broad, and is
highly asymmetric about the pulsar's velocity vector. This shape is not
consistent with that expected for the case of an isotropic wind interacting
with a homogeneous ambient medium. Models which invoke an anisotropy in the
pulsar wind, a bulk flow of the surrounding gas, or a density gradient in the
ambient medium either perpendicular or parallel to the pulsar's direction of
motion also fail to reproduce the observed morphology. However, we find an
ensemble of good fits to the nebular morphology when we consider a combination
of these effects. In all such cases, we find that the pulsar is propagating
through an ambient medium of mean density 0.8-1.3 cm^(-3) and bulk flow
velocity ~15-25 km/s and that the star has recently encountered an increase in
density by 1-10 cm^(-3) over a scale ~<0.02 pc. The wide variety of models
which fit the data demonstrate that in general there is no unique set of
parameters which can be inferred from the morphology of a bow-shock nebula.


title:
Comparing peanut-shaped `bulges' to N-body simulations and orbital
  calculations

abstract:
  We present a near-infrared K_n-band photometric study of edge-on galaxies
with a box/peanut-shaped `bulge'. The morphology of the galaxies is analysed
using unsharp masking and fits to the vertical surface brightness profiles, and
the results are compared to N-body simulations and orbital calculations of
barred galaxies. Both theoretical approaches reproduce the main structures
observed.


title: The Interior of Black Holes and their Astrophysics

abstract:
  Gravity warps space and time into a funnel and generates a black hole when a
cosmic body undergoes a catastrophic collapse. What can one say about the
interior of a black hole? The important point is that inside a black hole the
space radial direction becomes time, and time becomes a space direction. The
path into the gravitational abyss of the interior of a black hole is a
progression in time. There is a peculiar region inside a black hole where some
characteristics of the space-time curvature become singular. We call this
region singularity. The colossal tidal gravitational forces near singularity
modify physical laws. Space and time are not only strongly curved near the
singularity, but they split into quanta. The fall into the singularity is
unstoppable for a body inside a black hole. This paper also addresses the
following questions:
  Can one see what happens inside a black hole?
  Can a falling observer cross the singularity without being crushed?
  Can new baby universes arise inside a black hole?
  An answer to all these questions is probably ``yes''. We give also a brief
review of the modern black hole astrophysics.


title: On the time evolution of giant radio galaxies

abstract:
  A time evolution of giant lobe-dominated radio galaxies (with projected
linear size $D>1$ Mpc) is analysed on the basis of dynamical evolution of the
entire FRII-type population. Two basic physical parameters, namely the jet
power $Q_{0}$ and central density of the galaxy nucleus $\rho_{0}$ are derived
for a sample of giants with synchrotron ages reliably determined, and compared
with the relevant parameters in a comparison sample of normal-size sources
consisting of 3C, B2, and other sources. Having apparent luminosity (power) $P$
and linear size $D$ of each sample source, $Q_{0}$ and $\rho_{0}$ are fitted
using the dynamical model of Kaiser et al. (1997) but modified by allowing an
evolution of the cocoon axial ratio with time as suggested by Blundell et al.
(1999). In a result, we found that: (i) there is not a unique factor governing
the source size; giants are old sources with high enough jet power evolved in a
relatively low-density environment. The size is dependent, in order of
decreasing partial correlation coefficients, on age; then on $Q_{0}$; next on
$\rho_{0}$, (ii) a number of the sample sources, having similar $Q_{0}$ and
$\rho_{0}$ but different ages and axial ratios (called a `clan'), fit very well
the evolutionary luminosity-size ($P$-$D$) and energy density-total energy
tracks derived from the model for a `fiducial' source with $Q_{0}$ and
$\rho_{0}$ equal to the means of relevant values obtained for the `clan'
members. Therefore, these sources can be considered as `the same' source
observed at different epochs of its lifetime, and hence very useful for an
observational constraint of evolutionary models of the source dynamics, (iii)
in some cases a slow acceleration of the average expansion speed of the cocoon
along the jet axis seems to be present.


title:
Physical properties of two low-luminosity z ~ 1.9 galaxies behind the
  lensing cluster AC 114

abstract:
  We present VLT/ISAAC near-infrared spectroscopy of two gravitationally-lensed
z ~ 1.9 galaxies, A2 and S2, located behind the cluster AC 114. Thanks to large
magnification factors, we have been successful in detecting rest-frame optical
emission lines in star-forming galaxies 1 to 2 magnitudes fainter than in
previous studies of Lyman break galaxies (LBGs) at z ~ 3. From the Ha
luminosity, we estimate star formation rates (SFRs) which are 7 to 15 times
higher than those inferred from the UV continuum flux at 1500 ang without dust
extinction correction. The behavior of S2 and A2 in terms of O/H and N/O
abundance ratios are very different, and they are also different from typical
LBGs at z ~ 3. S2 is a low-metallicity object (Z ~ 0.03 Zsun) with a low N/O
ratio, similar to those derived in the most metal-poor nearby HII galaxies. In
contrast, A2 is a high-metallicity galaxy (Z ~ 1.3 Zsun) with a high N/O
abundance ratio, similar to those derived in the most metal-rich starburst
nucleus galaxies. The virial masses, derived from emission-line widths, are 0.5
and 2.4 x 10^10 Msun, for S2 and A2 respectively. Thanks to the gravitational
amplification, the line profiles of S2 are spatially resolved, leading to a
velocity gradient of +- 240 km/s, which yields a dynamical mass of ~ 1.3 x
10^10 Msun within the inner 1 kpc radius. Combining these new data with the
sample of LBGs at z ~ 3, we conclude that these three galaxies exhibit
different physical properties in terms of SFRs, abundance and mass-to-light
ratios, and reddening. High-redshift galaxies of different luminosities could
thus have quite different star formation histories (abridged version).


title: The largest black holes and the most luminous galaxies

abstract:
  The empirical relationship between the broad line region size and the source
luminosity in active galactic nuclei (AGNs) is used to obtain black holes (BH)
masses for a large number of quasars in three samples. The largests BH masses
found exceed 10^{10} Msun and are correlated, almost linearly, with the source
luminosity. Such BH masses, when converted to galactic bulge mass and
luminosity, indicate masses in excess of 10^{13} Msun and sigma(*) in excess of
700 km/sec. Such massive galaxies have never been observed. The largest BHs
reside, almost exclusively, in high redshift quasars. This, and the deduced BH
masses, suggest that several scenarios of BH and galaxy formation are
inconsistent with the observations. Either the observed size-L relationship in
low luminosity AGNs does not extend to very high luminosity or else the
M(BH)-M_B(bulge)-sigma(*) correlations observed in the local universe do not
reflect the relations of those quantities at the epoch of galaxy formation.


title: Kinematic outliers in the LMC: constraints on star-star microlensing

abstract:
  Although a decade of microlensing searches towards the Large Magellanic Cloud
(LMC) has detected 13-25 possible microlensing events, the nature and the
location of the lenses, being either halo machos or LMC stars, remains a
subject of debate. The star-star lensing models generically predict the
existence of a small population (more than about 5 percent of stars with a
spatial and kinematic distribution different from the thin, young disc of the
LMC. Here we present the results of a large spectroscopic survey of the LMC,
consisting of more than 1300 radial velocities measured accurately with the 2dF
instrument. In this large sample, no evidence is found for any extraneous
population over the expected LMC and Galactic components. Any additional,
kinematically distint, population can only be present at less than the 1
percent level. We discuss the significance of this finding for the LMC
self-lensing models.


title: Confirmation of persistent radio jets in the microquasar LS 5039

abstract:
  We present here new observations conducted with the EVN and MERLIN of the
persistent microquasar LS 5039 discovered by Paredes et al. (2000) with the
VLBA. The new observations confirm the presence of an asymmetric two-sided jet
reaching up to 1000 AU on the longest jet arm. The results suggest a bending of
the jets with increasing distance from the core and/or precession. The origin
and location of the high-energy gamma-ray emission associated with the system
is discussed and an estimate of the magnetic field at the base of the jet
given. Our results suggest a well collimated radio jet. We also comment on new
observing strategies to be used with satellites and forthcoming detectors,
since this persistent source appears to be a rather good laboratory to explore
the accretion/ejection processes taking place near compact objects.