title: Radiative Processes in Microquasars

abstract:
  Recent advances in the X-ray and soft gamma-ray observations of accreting
black holes and microquasars, in particular, are reviewed. The radiative
processes responsible for the emission are discussed briefly. The hybrid
thermal/nonthermal Comptonization model is shown to describe well the observed
broad-band spectra. We also comments on alternative phenomenological and
physical models that are used to describe the X/gamma-ray spectra of accreting
black holes. Among those are the "standard" model (i.e. disk-blackbody plus a
power-law), pexrav, bulk motion Comptonization, and synchrotron emission from
the jet.


title: Light Curve Analysis of Be Star Candidates in the Small Magellanic Cloud

abstract:
  The recent discovery, based on a search of public OGLE data, of Be star
candidates in the Small Magellanic Cloud showing spectacular photometric
variations (Mennickent et al. 2002), has motivated further analysis of their
light curves. Here we report the results of a statistical study of the light
curves of Type-1, Type-2 and Type-3 stars. Type-3 stars show a bimodal period
distribution, with a main, broad peak, between 20 and 130 days, and a narrower,
secondary peak, between 140 and 210 days. We also find that, among Type-3
stars, the maximum amplitude of oscillation correlates with the system
luminosity, in the sense that only low luminosity systems show large amplitude
oscillations. In general, the amplitude of these oscillations tends to increase
with the photometric period. A parametric study shows no correlation between
the amplitude, duration and asymmetry of Type-1 outbursts, and amplitude of
Type-2 jumps, with the available stellar photometric parameters.


title: Recent Results from the Wide Angle Search for Planets (WASP) Prototype

abstract:
  WASP0 is a prototype for what is intended to become a collection of WASPs
whose primary aim is to detect transiting extra-solar planets across the face
of their parent star. The WASP0 instrument is a wide-field (9-degree) 6.3cm
aperture F/2.8 Apogee 10 CCD camera (2Kx2K chip, 16-arcsec pixels). The camera
is mounted piggy-back on a commercial 10-inch Meade telescope. We present some
recent results from the WASP camera, including observations from La Palma of
the known transiting planet around HD 209458 and preliminary analysis of other
stars located in the same field. We also outline further problems which
restrict the ability to achieve photon limited precision with a wide-field
commercial CCD.


title: The 2MASS Tully-Fisher relation for flat edge-on galaxies

abstract:
  The spiral edge-on galaxies from the "Revised Flat Galaxy Catalog" (RFGC) are
identified with the Extended Source Catalog of the Two Micron All Sky Survey
(2MASS). A relative number of the 2MASS detected galaxies is 2996/4236 = 0.71.
We consider the statistical properties of the Tully-Fisher relations for the
edge-on galaxies in the B, I, J, H, and K_s bands. The slope of derived TF
relations increases steadily from 4.9 in the B band to 9.3 in the K one. The
effect is mainly due to the internal extinction which is different in dwarf and
giant spiral galaxies seen edge-on that leads to the tight correlation between
galaxy color and luminosity. The moderate scatter of the RFGC galaxies in the
`color-luminosity' diagram, 0.86 mag., provides us with a new "cheap" method of
mass measurements of distances to galaxies on the basis of modern photometric
sky surveys.


title: Weak lensing study of Abell 2029

abstract:
  Abell 2029 is one of the most studied clusters due to its proximity (z=0.07),
its strong X-ray brightness and its giant cD galaxy which is one of the biggest
stellar aggregates we know. We present here the first weak lensing mass
reconstruction of this cluster made from a deep I-band image of 28.5'x28.5'
centered on the cluster cD galaxy. This preliminary result allows us already to
show the shape similarities between the cD galaxy and the cluster itself,
suggesting that they form actually a single structure. We find a lower estimate
of the total mass of 1.8 10^14 h^-1 solar masses within a radius of 0.3 h^-1
Mpc. We finally compute the mass-to-cD-light ratio and its evolution as a
function of scale.


title:
Intrinsic Degeneracy of Gravitational Lens Time Delays: the case for a
  simple quadruple system in $\Lambda$CDM cosmology

abstract:
  A degeneracy in strong lens model is shown analytically. The observed time
delays and quasar image positions might {\it not} uniquely determine the
concentration and the extent of the lens galaxy halo mass distribution. Simply
hardwiring the Hubble constant ($H_0$) and the cosmology ($\Omega, \Lambda$) to
the standard values of $\Lambda$CDM cosmology might {\it not} fully lift this
degeneracy, which exists rigourously even with very accurate data. Equally good
fits to the images could be found in lens mass models with either a mostly
Keplerian or a flat rotation curve. This degeneracy in mass models makes the
task of getting reliable $H_0$ and $\Lambda$ from strong lenses even more
daunting.


title:
Ultra-High Energy Heavy Nuclei Propagation in Extragalactic Magnetic
  Fields

abstract:
  We extend existing work on the propagation of ultra-high energy cosmic rays
in extragalactic magnetic fields to a possible component of heavy nuclei,
taking into account photodisintegration, pion production, and creation of e+e-
pairs. We focus on the influence of the magnetic field on the spectrum and
chemical composition of observed ultra-high energy cosmic rays. We apply our
simulations to the scenarios proposed by Anchordoqui et al, in which Iron
nuclei are accelerated in nearby starburst galaxies, and show that it is in
marginal agreement with the data. We also show that it is highly unlikely to
detect He nuclei from M87 at the highest energies observed $\sim3 10^{20} $eV
as required for the scenario of Ahn et al. in which the highest energy cosmic
rays originate from M87 and are deflected in a Parker spiral Galactic magnetic
field.


title: The Chemical Uniformity of High z DLA Protogalaxies

abstract:
  We investigate chemical abundance variations along the sightlines through 13
damped Lya systems (DLA). We introduce a technique designed to identify
abundance variations in multiple velocity bins along the sightlines and perform
a series of Monte-Carlo simulations to derive quantitative limits and values.
The majority of these DLA have very uniform relative abundances: 95% c.l. upper
limits of 0.2 dex dispersion along the sightline and best fit values typically
<~0.1 dex. This surprising result indicates the gas comprising individual DLA
has similar enrichment history, nearly identical differential depletion, and
small abundance variations relating to ionization corrections. This uniformity
contrasts with stellar abundance variations observed within the Galaxy and with
the differences in abundances observed between galaxies of the Local group. It
also contrasts with variations in differential depletion along sightlines
through the SMC, LMC, and Milky Way. The results constrain the process of metal
production and dust formation in the early universe and reflect on scenarios of
galaxy formation. In terms of depletion the observations indicate a very low
porosity of significantly depleted gas, substantially lower than the filling
factor observed in present-day metal-poor galaxies. Finally, the observed
chemical uniformity may present a difficult challenge to scenarios which assume
individual DLA are comprised of multiple protogalactic clumps.


title:
STACEE Observations of Markarian 421 During an Extended Gamma-Ray
  Outburst

abstract:
  The active galaxy Markarian 421 underwent a substantial outburst in early
2001. Between January and May of that year, the STACEE detector was used to
observe the source in gamma-rays between the energies of 50 and 500 GeV. These
observations represent the lowest energy gamma-ray detection of this outburst
by a ground-based experiment. Here we present results from these observations,
which indicate an average integral gamma-ray flux of (8.0 +/- 0.7 +/-
1.5)x10^-10 1/cm^2/s. above 140 GeV. We also present a light curve for
Markarian 421 as observed by STACEE from March to May, and compare our
temporal, as well as spectral, measurements to those of other experiments.


title: White Dwarf Colors in Low Accretion Rate Binaries

abstract:
  Our recent theoretical work (Townsley and Bildsten 2002) on the thermal state
of white dwarfs (WDs) in low mass transfer rate binaries allows us to predict
the broadband colors of the binary from those of the WD and companion when the
disk is dim. The results based on standard CV evolution are presented h ere.
These will aid the discovery of such objects in field surveys and proper-motion
selected globular cluster surveys with HST; especially for the largely
unexplored post period minim um Cataclysmic Variables (CVs) with the lowest
accretion rates and degenerate companions. We have also calculated the fraction
of time that the WD resides in the ZZ Ceti instability strip thus clarifying
that we expect many accreting WDs to exhibit non-radial oscillations. The study
of these will provide new insights into the rotational and thermal structure of
an actively accreting WD.


title:
Preliminary Abundance Analysis of Galactic Bulge Main Sequence,
  Subgiant, and Giant Branch Stars Observed During Microlensing with Keck/HIRES

abstract:
  We present an abundance analysis of six main sequence turnoff, subgiant, and
giant branch stars toward the Galactic bulge that were observed with Keck/HIRES
during microlensing events. This is an early look at the first detailed
chemical analysis of main sequence stars in the Galactic bulge. Lensing events
allow the effective aperture of Keck to be increased beyond its current
dimensions; although, some events still stretched its spectroscopic
capabilities. Future large telescopes with high resolution and high throughput
spectrometers will allow the study of abundances in distant stellar populations
and in less evolved stars with greater ease.


title: Internal Conditions of Accreting White Dwarfs

abstract:
  We explain the physics of compressional heating of the deep interior of an
accreting white dwarf (WD) at accretion rates low enough so that the
accumulated hydrogen burns unstably and initiates a classical nova (CN). In
this limit, the WD core temperature (T_c) reaches an equilibrium value (T_c,eq)
after accreting an amount of mass much less than the WD's mass. Once this
equilibrium is reached, the compressional heating from within the envelope
exits the surface. This equilibrium yields useful relations between the WD
surface temperature, accretion rate and mass that can be employed to measure
accretion rates from observed WD effective temperatures, thus testing binary
evolution models for cataclysmic variables.


title: Magnetic Field Evolution in an Accreting White Dwarf

abstract:
  I discuss the evolution of the magnetic field of an accreting white dwarf. I
show that the ohmic decay time is 7-12 billion years for the lowest order decay
mode, almost independent of core temperature or mass. I then show that the
magnetic field structure is substantially altered by accretion if the white
dwarf mass increases at a rate more than 1-5 x 10^(-10) solar masses per year.
I discuss the implications of this result for observed systems, including the
possible evolutionary link between AM Hers and intermediate polars.


title: The Statistics of Extrasolar Planets: Results from the Keck Survey

abstract:
  We present an analysis of precision radial velocity measurements for 580
stars from the Keck survey. We first discuss the detection threshold of the
survey, and then describe a Bayesian approach to constrain the distribution of
extrasolar planet orbital parameters using both detections and upper limits.


title:
Determining the surface density distribution in massive galactic disks
  with a central black hole

abstract:
  An efficient method is developed which allows the calculation of
distributions of the surface density in the equilibrium disk configurations
with an isolated point mass at the center corresponding to known distributions
of the angular velocity. We demonstrate the existence of the upper limit for
the ratio `mass of the galactic disk / mass of the central black hole' which
essentially depends on the form of rotation-curves.


title: The Evolution of Cool Algols

abstract:
  We apply a model of dynamo-driven mass loss, magnetic braking and tidal
friction to the evolution of stars with cool convective envelopes; in
particular we apply it to binary stars where the combination of magnetic
braking and tidal friction can cause angular-momentum loss from the {\it
orbit}. For the present we consider the simplification that only one component
of a binary is subject to these non-conservative effects, but we emphasise the
need in some circumstances to permit such effects in {\it both} components.
  The model is applied to examples of (i) the Sun, (ii) BY Dra binaries, (iii)
Am binaries, (iv) RS CVn binaries, (v) Algols, (vi) post-Algols. A number of
problems regarding some of these systems appear to find a natural explanation
in our model. There are indications from other systems that some coefficients
in our model may vary by a factor of 2 or so from system to system; this may be
a result of the chaotic nature of dynamo activity.


title: Magnetar-like X-ray Bursts from an Anomalous X-ray Pulsar

abstract:
  Anomalous X-ray Pulsars (AXPs) are a class of rare X-ray pulsars whose energy
source has been perplexing for some 20 years. Unlike other, better understood
X-ray pulsars, AXPs cannot be powered by rotation or by accretion from a binary
companion, hence the designation ``anomalous.'' AXP rotational and radiative
properties are strikingly similar to those of another class of exotic objects,
the Soft Gamma Repeaters (SGRs). However, the defining property of SGRs, namely
their low-energy gamma-ray and X-ray bursts, have heretofore not been seen in
AXPs. SGRs are thought to be ``magnetars,'' young neutron stars powered by the
decay of an ultra-high magnetic field. The suggestion that AXPs are magnetars
has been controversial. Here we report the discovery, from the direction of AXP
1E 1048-5937, of two X-ray bursts that have many properties similar to those of
SGR bursts. These events imply a close relationship between AXPs and SGRs, with
both being magnetars.


title: Envelope Ejection: an Alternative Process for some Early Case B Binaries

abstract:
  We discuss the evolution of binaries with moderately high masses (about 10 -
30 solar masses), and with periods of about 3 - 300d, corresponding mostly to
early Case B. These are usually thought to evolve either by reasonably
conservative Roche-lobe overflow, if the initial mass ratio is fairly mild, or
else by highly non-conservative common-envelope evolution, with spiral-in to
short periods (hours, typically), if the initial mass ratio is rather extreme.
We discuss here a handful of binaries from part of this period range (about 50
- 250d), which appear to have followed a different path: we argue that they
must have lost a large proportion of initial mass (about 70 - 80%), but without
shortening their periods at all. We suggest that their behaviour may be due to
the fact that stars of such masses, when evolved also to rather large radii,
are not far from the Humphreys-Davidson limit where single stars lose their
envelopes spontaneously in P Cygni winds, and so have envelopes which are only
lightly bound to the core. These envelopes therefore may be relatively easily
dissipated by the perturbing effect of a companion. In addition, some or all of
the stars considered here may have been close to the Cepheid instability strip
when they filled their Roche lobes. One or other, or both, of high luminosity
and Cepheid instability, in combination with an appropriately close binary
companion, may be implicated.


title: Multicolor photometry of 145 of the HII regions in M33

abstract:
  This paper is the first in a series presenting CCD multicolor photometry for
145 HII regions, selected from 369 candidate regions from Boulesteix et al.
(1974), in the nearby spiral galaxy M33. The observations, which covered the
whole area of M33, were carried out by the Beijing Astronomical Observatory
60/90 cm Schmidt Telescope, in 13 intermediate-band filters, covering a range
of wavelength from 3800 to 10000 A. This provides a series of maps which can be
converted to a multicolor map of M33, in pixels of 1.7''*1.7''. Using aperture
photometry we obtain the spectral energy distributions (SEDs) for these HII
regions. We also give their identification charts. Using the relationship
between the BATC intermediate-band system used for the observations and the
UBVRI broad-band system, the magnitudes in the B and V bands are then derived.
Histograms of the magnitudes in V and in B-V are plotted, and the
color-magnitude diagram is also given. The distribution of magnitudes in the V
band shows that the apparent magnitude of almost all the regions is brighter
than 18, corresponding to an absolute magnitude of -6.62 for an assumed
distance modulus of 24.62, which corresponds to a single main sequence O5 star,
while the distribution of color shows that the sample is blue, with a mode
close to -0.05 as would be expected from a range of typical young clusters.


title:
Chandra Observations of Abell 2029: The Dark Matter Profile Down to
  <0.01 R_vir in an Unusually Relaxed Cluster

abstract:
  We have used a high resolution Chandra observation to examine the core mass
distribution of the unusually regular cD cluster Abell 2029. This system is
especially well-suited for analysis of its mass distribution under the
assumption of hydrostatic equilibrium: it exhibits an undisturbed X-ray
morphology and a single-phase ICM. We estimate the total mass, and the
contributions of the gas and dark matter components from <3 arcsec to ~3 arcmin
(<4.4-260 kpc, 0.001-0.1 r_vir). The gas density is well fitted by either a
double beta-model, or a ``cusped'' beta-model. The temperature data are
increasing, and can be approximated by a power-law, with alpha_T = 0.27+/-0.01.
  Fitting smooth functions to density and T, we obtain a mass profile, which is
remarkably well described down to 0.002 r_vir by the NFW model, for which we
measure r_scale = 540+/-90 kpc (~0.2 r_vir) and c = 4.4 +/- 0.9. The mass
profile is also approximated by a power-law fit with alpha_m = 1.81+/-0.04
(corresponding to a logarithmic density slope of -1.19+/-0.04). The density
profile is too shallow to be fitted with a Moore et al. model. The consistency
with NFW at <0.01 r_vir is incompatible with SIDM, and contrasts with the
results from rotation curves of LSB and dwarf galaxies. This suggests that
while CDM may adequately describe clusters, it does not currently account
properly for small halos.
  Using the cD light, we observe a total M/L_V ~ 12 at r < 20 kpc, rising to >
100 beyond 200 kpc. The consistency with an NFW halo model and the large M/L
suggest the cluster is DM-dominated down to <~ 0.005 r_vir. We observe a gas
mass fraction = 0.139+/-0.004 at the limit of our observations, finding an
upper limit to Omega_m <= 0.29+/-0.03 (abridged).


title:
On the Oosterhoff Classification of the Unusual, Metal-Rich Globular
  Clusters NGC 6388 and NGC 6441

abstract:
  We discuss the Oosterhoff classification of the unusual, metal-rich globular
clusters NGC 6388 and NGC 6441, on the basis of new evolutionary models
computed for a range of metallicities. Our results confirm the difficulty in
unambiguously classifying these clusters into either Oosterhoff group, and also
question the view that RR Lyrae stars in Oosterhoff type II globular clusters
can all be evolved from a position on the blue zero-age horizontal branch.


abstract:
  The Master Catalogue of stars towards the Magellanic Clouds (MC2) is a
multi-wavelength reference catalogue. The current paper presents the first
results of the MC2 project. We started with a massive cross-identification of
the two recently released near-infrared surveys: the DENIS Catalogue towards
the Magellanic Clouds (DCMC) with more than 1.3 million sources identified in
at least two of the three DENIS filters (I J Ks) and the 2nd Incremental
Release of the 2MASS point source catalogue (J H Ks) covering the same region
of the sky. Both point source catalogues provide an unprecedented wealth of
data on the stellar populations of the Magellanic Clouds (MCs). The
cross-matching procedure has been extended to optical wavelength ranges,
including the UCAC1 (USNO) and GSC2.2 catalogues. New cross-matching procedures
for very large catalogues have been developed and important results on the
astrometric and photometric accuracy of the cross-identified catalogues were
derived. The cross-matching of large surveys is an essential tool to improve
our understanding of their specific contents. This study has been partly
supported by the ASTROVIRTEL project that aims at improving access to
astronomical archives as virtual telescopes.


title: Clustering statistics in cosmology

abstract:
  The main tools in cosmology for comparing theoretical models with the
observations of the galaxy distribution are statistical. We will review the
applications of spatial statistics to the description of the large-scale
structure of the universe. Special topics discussed in this talk will be:
description of the galaxy samples, selection effects and biases, correlation
functions, Fourier analysis, nearest neighbor statistics, Minkowski functionals
and structure statistics. Special attention will be devoted to scaling laws and
the use of the lacunarity measures in the description of the cosmic texture.


title: A "Freely Coasting" Universe

abstract:
  A strictly linear evolution of the cosmological scale factor is surprisingly
an excellent fit to a host of cosmological observations. Any model that can
support such a coasting presents itself as a falsifiable model as far as
classical cosmological tests are concerned. This article discusses the
concordance of such an evolution in relation to several standard observations.
Such evolution is known to be comfortably concordant with the Hubble diagram as
deduced from current supernovae 1a data, it passes constraints arising from the
age and gravitational lensing statistics and just about clears basic
constraints on nucleosynthesis. Such an evolution exhibits distinguishable and
verifiable features for the recombination era. The overall viability of such
models is discussed.


title: Probing the dark energy with strong lensing by clusters of galaxies

abstract:
  Observations of clusters of galaxies that gravitationally lens faint
background galaxies can probe the amount and the equation of state, $\5$, of
the dark energy (quintessence) in the universe. Provided that the mass profile
and the mass normalization of the cluster are determined, it is possible to
constrain the cosmological parameters that enter the lensing equations by means
of the angular diameter distances, by locating (either by observations of giant
arcs and magnification bias effect) the critical lines corresponding to known
redshift source populations of galaxies. This method can help to distinguish
between accelerating and decelerating models of the universe. Furthermore,
since the position of critical lines is affected, especially in low-matter
density universes, by the properties of quintessence, the observations of a
suitable number of lensing clusters at intermediate redshifts can determine the
equation of state. A very preliminary application of the method to the cluster
CL 0024+1654 seems to support a flat accelerating universe dominated by dark
energy.


title: No disk needed around HD 199143 B

abstract:
  We present new, high angular resolution images of HD 199143 in the
Capricornus association, obtained with the adaptive optics system
ADONIS+SHARPII at the ESO 3.6m Telescope of La Silla Observatory. HD 199143 and
its neighbour star HD 358623 (separation 5'away) have previously been imaged
with adaptive optics. For each star, a companion has been detected in the J and
K bands at respective separations of 1.1'' and 2.2'' (Jayawardhana & Brandeker
2001). Our new photometry of HD 199143 B suggests that it is a M2 star and that
the presence of circumstellar dust proposed by Van den Ancker et al. (2000) is
no longer necessary. We show that the 12 microns flux detected by IRAS
previously interpreted as an IR excess, can be explained by the presence of the
late-type companion.


title:
1245+676 - a CSO/GPS source being an extreme case of a double-double
  structure

abstract:
  AGN with the so-called `double-double' radio structure have been interpreted
as restarted AGN where the inner structure is a manifestation of a new phase of
activity which happened to begin before the outer radio lobes resulting from
the previous one had faded completely. The radio galaxy 1245+676 is an extreme
example of such a double-double object - its outer structure, measuring 970
h^{-1} kpc, is five orders of magnitude larger than the 9.6 h^{-1} pc inner
one. We present a series of VLBI observations of the core of 1245+676 which
appears to be a compact symmetric object (CSO). We have detected the motion of
the CSO's lobes, measured its velocity, and inferred the kinematic age of that
structure.


title: Test problems for relativistic magnetohydrodynamics

abstract:
  Some of the parameters of the test problems for numerical relativistic MHD
given in Table 1 in Komissarov(1999) are incorrect. Here we give the correct
values.


title: Bar strengths in spiral galaxies estimated from 2MASS images

abstract:
  Non-axisymmetric forces are presented for 107 spiral galaxies using the 2
Micron All Sky Survey (2MASS) images. We apply both Cartesian integration and a
polar grid integration utilizing a limited number of azimuthal Fourier
components of density. We found that bar strength is independent of the method
used to evaluate the gravitational potential. However, the polar method is more
suitable for weak and noisy images. Bar strength was found to be sensitive to
the Hubble-type dependent scale height of the disk, which has been ignored in
the previous studies. On the other hand, the method is rather insensitive to
the vertical model of the disk, as long as a same vertical dispersion is
assumed, or to the boxy/peanut shaped structure, studied in terms of
non-constant vertical scale height along the disk. In the near-IR most galaxies
in our sample show non-axisymmetric forces in some level, and 40 percent of
them have bars in a sense that they have regions with a constant phase of the
m=2 Fourier density component.


title: Anisotropies of the Cosmic Microwave Background

abstract:
  We review the present status of Cosmic Microwave Background (CMB) anisotropy
observations and discuss the main related astrophysical issues, instrumental
effects and data analysis techniques. We summarise the balloon-borne and
ground-based experiments that, after COBE-DMR, yielded detection or significant
upper limits to CMB fluctuations. A comparison of subsets of combined data
indicates that the acoustic features observed today in the angular power
spectrum are not dominated by undetected systematics. Pushing the accuracy of
CMB anisotropy measurements to their ultimate limits represents one of the best
opportunities for cosmology to develop into a precision science in the next
decade. We discuss the forthcoming sub-orbital and space programs, as well as
future prospects of CMB observations.


title:
Nonlinear clustering during the cosmic Dark Ages and its effect on the
  21-cm background from minihalos

abstract:
  Hydrogen atoms inside virialized minihalos generate a radiation background
from redshifted 21-cm line emission whose angular fluctuations reflect
clustering during before and during reionization. We have shown elsewhere that
this emission may be detectable with the planned Low Frequency Array (LOFAR)
and Square Kilometer Array (SKA) in a flat LambdaCDM. This is a direct probe of
structure during the ``Dark Ages'' at redshifts z>6 and down to smaller scales
than have previously been constrained. In our original calculation, we used a
standard approximation known as the ``linear bias'' [e.g. Mo & White (1996)].
Here we improve upon that treatment by considering the effect of nonlinear
clustering. To accomplish this, we develop a new analytical method for
calculating the nonlinear Eulerian bias of halos, which should be useful for
other applications as well. Predictions of this method are compared with the
results of LambdaCDM N-body simulations, showing significantly better agreement
than the standard linear bias approximation. When applied to the 21-cm
background from minihalos, our formalism predicts fluctuations that differ from
our original predictions by up to 30% at low frequencies and small scales.
However, within the range of frequencies and angular scales at which the signal
could be observable by LOFAR and SKA as currently planned, the differences are
small and our original predictions prove robust. Our results indicate that
while a smaller frequency bandwidth of observation leads to a higher signal
that is more sensitive to nonlinear effects, this effect is counteracted by the
lowered sensitivity of the radio arrays. We calculate the best frequency
bandwidth for these observations to be Delta nu~2 MHz.(abbreviated)


title:
Fine-structure in the nonthermal X-ray emission of SNR RX J1713.7-3946
  revealed by Chandra

abstract:
  We present morphological and spectroscopic studies of the northwest rim of
the supernova remnant RX J1713.7-3946 based on observations by the Chandra
X-ray observatory. We found a complex network of nonthermal (synchrotron) X-ray
filaments, as well as a 'void' type structure -- a dim region of a circular
shape -- in the northwest rim. It is remarkable that despite distinct
brightness variations, the X-ray spectra everywhere in this region can be well
fitted with a power-law model with photon index around 2.3. We briefly discuss
some implications of these results and argue that the resolved X-ray features
in the northwest rim may challenge the perceptions of standard (diffusive
shock-acceleration) models concerning the production, propagation and radiation
of relativistic particles in supernova remnants.


title: The Radio Luminosity Function of Cluster Radio Halos

abstract:
  A significant fraction of galaxy clusters exhibits cluster wide radio halos.
We give a simple prediction of the local and higher redshift radio halo
luminosity function (RHLF) on the basis of (i) an observed and a theoretical
X-ray cluster luminosity function (XCLF) (ii) the observed radio--X-ray
luminosity correlation (RXLC) of galaxy clusters with radio halos (iii) an
assumed fraction of 1/3 galaxy clusters to have radio halos as supported by
observations. We then find 300-700 radio halos with S_1.4GHz > 1 mJy, and 10^5
- 10^6 radio halos with S_1.4GHz > 1 muJy should be visible on the sky. 14% of
the S_1.4GHz > 1 mJy and 56% of the S_1.4GHz > 1 muJy halos are located at
z>0.3. Subsequently, we give more realistic predictions taking into account
(iv) a refined estimate of the radio halo fraction as a function of redshift
and cluster mass, and (v) a decrease in intrinsic radio halo luminosity with
redshift due to increased inverse Compton electron energy losses on the Cosmic
Microwave Background (CMB). We find that this reduces the radio halo counts
from the simple prediction by only 30 % totally, but the high redshift (z>0.3)
counts are more strongly reduced by 50-70%. These calculations show that the
new generation of sensitive radio telescopes like LOFAR, ATA, EVLA, SKA and the
already operating GMRT should be able to detect large numbers of radio halos
and will provide unique information for studies of galaxy cluster merger rates
and associated non-thermal processes.


title: Konus catalog of short GRBs

abstract:
  Observational data on the short GRBs obtained with the GGS-Wind Konus
experiment in the period from 1994 to 2002 are presented. The catalog currently
includes 130 events, detailing their appearance rate, time histories, and
energy spectra. Evidence of an early X-ray and gamma-ray afterglow for some of
the short GRBs is discussed. The catalog is available electronically at
http://www.ioffe.ru/LEA/shortGRBs/Catalog/


title:
Integrated Spectroscopy of Bulge Globular Clusters and Fields. II.
  Implications for stellar population models and elliptical galaxies

abstract:
  Synthetic Lick indices (e.g. Mg_2, Fe, etc.) of Simple Stellar Population
(SSP) models are calibrated for the first time up to solar metallicity with a
sample of Milky Way globular clusters (GCs) which includes the metal rich GCs
of the Galactic bulge. This metallicity range is relevant to elliptical
galaxies. It is shown that the Bulge GCs and integrated light follow the same
correlation between Mg and Fe indices of elliptical galaxies, showing weaker Fe
indices at given Mg indices with respect to models that assume solar-scaled
abundances. This similarity is the robust empirical evidence for enhanced
alpha/Fe ratios in the stellar populations of elliptical galaxies, since the
globular clusters are independently known to be alpha-enhanced. The uniqueness
of this alpha-overabundance solution is checked by exploring the whole range of
model ingredients. We argue that the standard models reproduce the Mg-Fe
correlation at low metallicities because the stellar templates used in the
synthesis are the alpha-enhanced stars of the galactic Halo. These same models,
however, fail to recover the Mg-Fe pattern of Bulge clusters and ellipticals at
high metallicities because the high-metallicity templates are disk stars, which
are not alpha-enhanced. The new SSP models by Thomas, Maraston & Bender (2002)
which incorporate the dependence on alpha/Fe reproduce the Mg and Fe indices of
GCs at all metallicities, with alpha/Fe=+0.3, which is in agreement with
spectroscopic abundance determinations. The Balmer indices (Hbeta, Hdelta,
Hgamma) are very well calibrated, provided the Horizontal Branch morphology is
taken into account. In particular, we reproduce the Balmer lines of NGC 6388
and NGC 6441, which are metal-rich GCs with a tail of warm Horizontal Branch
stars. {Abridged}


title: SHEEP: The Search for the High Energy Extragalactic Population

abstract:
  We present the SHEEP survey for serendipitously-detected hard X-ray sources
in ASCA GIS images. In a survey area of $\sim 40$ deg$^{2}$, 69 sources were
detected in the 5-10 keV band to a limiting flux of $\sim 10^{-13}$ erg
cm$^{-2}$ s$^{-1}$. The number counts agree with those obtained by the similar
BeppoSAX HELLAS survey, and both are in close agreement with ASCA and BeppoSAX
2-10 keV surveys. Spectral analysis of the SHEEP sample reveals that the 2-10
and 5-10 keV surveys do not sample the same populations, however, as we find
considerably harder spectra, with an average $\Gamma\sim1.0$ assuming no
absorption. The implication is that the agreement in the number counts is
coincidental, with the 5-10 keV surveys gaining approximately as many hard
sources as they lose soft ones, when compared to the 2-10 keV surveys. This is
hard to reconcile with standard AGN ``population synthesis'' models for the
X-ray background, which posit the existence of a large population of absorbed
sources. We find no evidence of the population hardening at faint fluxes, with
the exception that the few very brightest objects are anomalously soft. 53 of
the SHEEP sources have been covered by ROSAT in the pointed phase. Of these 32
were detected. An additional 3 were detected in the RASS. As expected the
sources detected with ROSAT are systematically softer than those detected with
ASCA alone, and of the sample as a whole (truncated).


title:
UVES Abundances of Stars in Nearby Galaxies: How Good are Theoretical
  Isochrones?

abstract:
  Here we report some results from an ESO-VLT programme to observe individual
stars in nearby dwarf galaxies at high resolution with the UVES spectrograph
(Tolstoy, Venn, Shetrone, Primas, Hill, Kaufer & Szeifert 2002, submitted to
AJ). We mainly concentrate on illustrating the issues and uncertainties
surrounding our efforts to determine the ages of stars for which we have
accurately measured [Fe/H] and [alpha/Fe].


title: A Way to the Dark Side of the Universe through Extra Dimensions

abstract:
  As indicated by Einstein's general relativity, matter and geometry are two
faces of a single nature. In our point of view, extra dimensions, as a member
of the {\em geometry face}, will be treated as a part of the {\em matter face}
when they are beyond our poor vision, thereby providing dark energy sources
effectively. The geometrical structure and the evolution pattern of extra
dimensions therefore may play an important role in cosmology. Various possible
impacts of extra dimensions on cosmology are investigated. In one way, the
evolution of homogeneous extra dimensions may contribute to dark energy,
driving the accelerating expansion of the universe. In the other way, both the
energy perturbations in the ordinary three-space, combined with homogeneous
extra dimensions, and the inhomogeneities in the extra space may contribute to
dark matter. In this paper we wish to sketch the basic idea and show how extra
dimensions may lead to the dark side of our universe.


title:
An Infrared Multiplicity Survey of Class I/Flat-Spectrum Systems in the
  Rho Ophiuchi and Serpens Molecular Clouds

abstract:
  We present new near- and mid-infrared observations of 19 Class
I/flat-spectrum young stellar objects in the nearby Rho Oph (d=125pc) and
Serpens (d=310pc) dark clouds. These observations are part of a larger
systematic infrared multiplicity survey of Class I/flat-spectrum objects in the
nearest dark clouds. We find 7/19 (37% +/- 14%) of the sources surveyed to be
multiple systems over a separation range of ~150 - 1800 AU. This is consistent
with the fraction of multiple systems found among older pre-main-sequence stars
in each of the Taurus, Rho Oph, Chamaeleon, Lupus, and Corona Australis
star-forming regions over a similar separation range. However, solar-type
main-sequence stars in the solar neighborhood have a fraction approximately
one-third that of our Class I/flat- spectrum sample (11% +/- 3%). This may be
attributed to evolutionary effects or environmental differences. An examination
of the spectral energy distributions of the SVS 20 and WL 1 binaries reveals
that the individual components of each source exhibit the same SED
classifications, similar to what one typically finds for binary T Tauri star
(TTS) systems, where the companion of a classical TTS also tends to be of the
same SED type.


title: Spectral Lines from Rotating Neutron Stars

abstract:
  The line profiles from rotating neutron stars are affected by a number of
relativistic processes such as Doppler boosts, strong self-lensing,
frame-dragging, and the differential gravitational redshift arising from the
stellar oblateness. In this Letter, we calculate line profiles taking into
account the first two effects, which is accurate for rotation rates less than
the breakup frequency. We show that the line profiles are not only broadened
and weakened but are also significantly asymmetric, and allow for an
independent measurement of both the mass and the radius of the neutron star.
Furthermore, we investigate the case when a fraction of the neutron star
surface contributes to the emission and find that the line profiles are
typically doubly peaked. We discuss the implications of our results for
searches for line features in the spectra of isolated neutron stars and X-ray
bursters. We finally assess the systematic uncertainties introduced by the line
asymmetry in inferring the compactness of neutron stars from the detection of
redshifted lines.


title:
Chandra Spectroscopy and Mass Estimation of the Lensing Cluster of
  Galaxies CL0024+17

abstract:
  We present the X-ray analysis and the mass estimation of the lensing cluster
of galaxies CL0024+17 with Chandra. We found that the temperature profile is
consistent with being isothermal and the average X-ray temperature is 4.47
(+0.83, -0.54) keV. The X-ray surface brightness profile is represented by the
sum of emissions associated with the central three bright elliptical galaxies
and the emission from intracluster medium (ICM) which can be well described by
a spherical beta-model. Assuming the ICM to be in the hydrostatic equilibrium,
we estimated the X-ray mass and found it is significantly smaller than the
strong lensing mass by a factor of 3.


title: Changing Face of the Extrasolar Giant Planet, HD 209458b

abstract:
  High-resolution atmospheric flow simulations of the tidally-locked extrasolar
giant planet, HD 209458b, show large-scale spatio-temporal variability. This is
in contrast to the simple, permanent day/night (i.e., hot/cold) picture. The
planet's global circulation is characterized by a polar vortex in motion around
each pole and a banded structure corresponding to ~3 broad zonal (east-west)
jets. For very strong jets, the circulation-induced temperature difference
between moving hot and cold regions can reach up to ~1000 K, suggesting that
atmospheric variability could be observed in the planet's spectral and
photometric signatures.


title: Neutron-Fed Afterglows of Gamma-Ray Bursts

abstract:
  Fireballs of gamma-ray bursts are partially made of free neutrons. Their
presence crucially changes the mechanism of the fireball deceleration by an
external medium. At late stages of the explosion, neutrons fully decouple from
ions and coast with a constant Lorentz factor \Gamma_n. As the ion fireball
decelerates, the neutrons form a leading front. This front gradually decays,
leaving behind a trail of decay products mixed with the ambient medium. The
kinetic energy of the decay products far exceeds the medium rest-mass energy,
and the trail has a high Lorentz factor at radii R < R_{trail} = 10R_\beta
\approx 10^{17} cm where R_\beta = 10^{16}(\Gamma_n/300) cm is the mean radius
of neutron decay. The ion fireball sweeps up the trail material and drives a
shock wave in it. Thus, observed afterglow emission is produced in the neutron
trail. It can naturally re-brighten or display a spectral transition at R
\approx R_{trail} where the impact of neutrons turns off. Absence of any
neutron signatures would point to an extremely low baryon loading of the
fireballs and a strong dominance of a Poynting flux.


title:
A Survey of FUSE and HST Sightlines through High-Velocity Cloud Complex
  C

abstract:
  Using archival Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space
Telescope (HST) data, we have assembled a survey of eight sightlines through
high-velocity cloud Complex C. Abundances of the observed ion species vary
significantly for these sightlines, indicating that Complex C is not well
characterized by a single metallicity. Reliable metallicities based on [OI/HI]
range from 0.1-0.25 solar. Metallicities based on [SII/HI] range from 0.1-0.6
solar, but the trend of decreasing abundance with HI column density indicates
that photoionization corrections may affect the conversion to [S/H]. We present
models of the dependence of the ionization correction on HI column density;
these ionization corrections are significant when converting ion abundances to
elemental abundances for S, Si, and Fe. The measured abundances in this survey
indicate that parts of the cloud have a higher metallicity than previously
thought and that Complex C may represent a mixture of ``Galactic fountain'' gas
with infalling low-metallicity gas. We find that [S/O] and [Si/O] have a solar
ratio, suggesting little dust depletion. Further, the measured abundances
suggest an over-abundance of O, S, and Si relative to N and Fe. The enhancement
of these alpha-elements suggests that the bulk of the metals in Complex C were
produced by Type II supernovae and then removed from the star-forming region,
possibly via supernovae-driven winds or tidal stripping, before the ISM could
be enriched by N and Fe.


title:
High energy photon flux prediction from neutralino annihilation in the
  globular cluster Palomar 13

abstract:
  The distant globular cluster Palomar 13 has been found to have a very high
mass-to-light ratio and its profile can be well fitted either by a King model
with a tail, or with a NFW model. This cluster may be the first case of the
many clumps predicted by CDM simulations that would not be disrupted by the
galactic halo potential. We make the hypothesis that Pal 13 is made of
neutralinos and run the DarkSuspect code to estimate the high-energy photon
flux due to the annihilation of neutralinos through various channels in some
benchmark scenarios. These low fluxes may be used as targets to be reached in
proposals for future ground-based high altitude Cerenkov telescopes.


title: Neutral Beams from Blazar Jets

abstract:
  We treat the production of neutrons, photons, and neutrinos through
photomeson interactions of relativistic protons with ambient photons in the
compact inner jets of blazars. We show that the presence of the external UV
radiation field makes possible strong energy losses already for protons with
energies > 1 PeV, while without this component effective energy losses of
protons begin only at E > 10^{18} eV. We develop a model describing the
production and escape of neutrons from a comoving spherical blob, which
continue to interact with the ambient external radiation field on the
parsec-scale broad line region (BLR). Neutrons may carry ~10% of the overall
energy of the protons accelerated beyond E ~ 1 PeV outside the BLR. Ultra-high
energy (UHE) gamma rays produced in photomeson interactions of neutrons outside
the blob can also escape the BLR. The escaping neutrons, gamma rays and
neutrinos form a collimated neutral beam with a characteristic opening angle ~
1/Gamma, where Gamma is the bulk Lorentz factor of the inner jet. The energy
and the momentum of such beam is then mostly deposited in the extended jet due
to neutron decay at distances ~ (E_n/10^{17} eV}) kpc, and through
pair-production attenuation of gamma rays with energies E_g ~ 10^{15}-10^{18}
eV which can propagate to distances beyond (10-100) kpc. In this scenario,
neutral beams of UHE gamma rays and neutrons can be the reason for straight
extended jets such as in Pictor A. Fluxes of neutrinos detectable with km-scale
neutrino telescopes are predicted from flat spectrum radio quasars such as 3C
279.


title:
Kinematical solution of the UHE-cosmic-ray puzzle without a preferred
  class of inertial observers

abstract:
  Among the possible explanations for the puzzling observations of cosmic rays
above the GZK cutoff there is growing interest in the ones that represent
kinematical solutions, based either on general formulations of particle physics
with small violations of Lorentz symmetry or on a quantum-gravity-motivated
scheme for the breakup of Lorentz symmetry. An unappealing aspect of these
cosmic-ray-puzzle solutions is that they require the existence of a preferred
class of inertial observers. Here I propose a new kinematical solution of the
cosmic-ray puzzle, which does not require the existence of a preferred class of
inertial observers. My proposal is a new example of a type of relativistic
theories, the so-called "doubly-special-relativity" theories, which have
already been studied extensively over the last two years. The core ingredient
of the proposal is a deformation of Lorentz transformations in which also the
Planck scale $E_p$ (in addition to the speed-of-light scale $c$) is described
as an invariant. Just like the introduction of the invariant $c$ requires a
deformation of the Galileian transformations into the Lorentz transformations,
the introduction of the invariant $E_p$ requires a deformation of the Lorentz
transformations, but there is no special class of inertial observers. The
Pierre Auger Observatory and the GLAST space telescope should play a key role
in future developments of these investigations. I also emphasize that the
doubly-special-relativity theory here proposed, besides being the first one to
provide a solution for the cosmic-ray puzzle, is also the first one in which a
natural description of macroscopic bodies is achieved, and may find
applications in the context of a recently-proposed dark-energy scenario.


title: Dramatic Changes in the Outburst Properties in V503 Cygni

abstract:
  We examined the VSNET light curve of the unusual SU UMa-type dwarf nova V503
Cyg which is known to show a short (89 d) supercycle length and exceptionally
small (a few) normal outbursts within a supercycle. In 1999-2000, V503 Cyg
displayed frequent normal outbursts with typical recurrence times of 7-9 d. The
behavior during this period is characteristic to an usual SU UMa-type dwarf
nova with a short supercycle length. On the other hand, V503 Cyg showed very
infrequent normal outbursts in 2001-2002. Some of the superoutbursts during
this period were observed shorter than usual. The remarkable alternations of
the outbursting states in V503 Cyg support the presence of mechanisms of
suppressing normal outbursts and premature quenching superoutbursts, which have
been proposed to explain some unusual SU UMa-type outbursts. The observed
temporal variability of the suppressing/quenching mechanisms in the same object
suggests that these mechanisms are not primarily governed by a fixed system
parameter but more reflect state changes in the accretion disk.


title: The Central Parsecs of the Bright Quasar PKS 1921 - 293

abstract:
  We report on a VLBA imaging study of the nearby bright southern blazar PKS
1921 - 293 (OV - 236). High resolution VLBA observations, made at four
frequencies (5, 12, 15, and 43 GHz) over the period 1994 - 2000, have revealed
a strongly curved jet extending out to about 50 parsecs from the presumed
central engine. Two epoch VLBA observations, each simultaneously carried out at
both 5 and 43 GHz, show a large position angle difference of 51 - 67 degrees
between the jet emission at 5 and 43 GHz. Although the core of PKS 1921 - 293
has one of the highest brightness temperatures measured in any compact radio
source, unlike other bright blazars it is not a source of gamma-ray emission.
However, there is evidence in these images for superluminal motion within the
central region (a few parsecs from the core) and within the north-east diffuse
emission region. In all six-epoch 43 GHz images, two equally compact bright
components within the central parsec are seen.


title:
The UV (GALEX) and FIR (ASTRO-F) All Sky Surveys: the measure of the
  dust extinction in the local universe

abstract:
  Before the end of 2002 will be launched the GALEX satellite (a NASA/SMEX
project) which will observe all the sky in Ultraviolet (UV) through filters at
1500 and 2300 A down to m(AB) 21. In 2004 will be launched the ASTRO-F
satellite which will perform an all sky survey at Far-Infrared (FIR)
wavelengths.
  The cross-correlation of both surveys will lead to very large samples of
galaxies for which FIR and UV fluxes will be available. Using the FIR to UV
flux ratio as a quantitative tracer of the dust extinction we will be able to
measure the extinction in the nearby universe (z<0.2) and to perform a
statistically significant analysis of the extinction as a function of galactic
properties. Of particular interest is the construction of pure FIR and UV
selected samples for which the extinction will be measured as templates for the
observation of high redshift galaxies.


title: Magnetic Flares on Asymptotic Giant Branch Stars

abstract:
  We investigate the consequences of magnetic flares on the surface of
asymptotic giant branch (AGB) and similar stars. In contrast to the solar wind,
in the winds of AGB stars the gas cooling time is much shorter than the outflow
time. As a result, we predict that energetic flaring will not inhibit, and may
even enhance, dust formation around AGB stars. If magnetic flares do occur
around such stars, we expect some AGB stars to exhibit X-ray emission; indeed
certain systems including AGB stars, such as Mira, have been detected in
X-rays. However, in these cases, it is difficult to distinguish between
potential AGB star X-ray emission and, e.g., X-ray emission from the vicinity
of a binary companion. Analysis of an archival ROSAT X-ray spectrum of the Mira
system suggests an intrinsic X-ray luminosity 2x10^{29} erg/sec and temperature
10^7 K. These modeling results suggest that magnetic activity, either on the
AGB star (Mira A) or on its nearby companion (Mira B), is the source of the
X-rays, but do not rule out the possibility that the X-rays are generated by an
accretion disk around Mira B.


title:
Prospects for SNIa Explosion Mechanism Identification Through Supernova
  Remnants

abstract:
  We present the first results from an ongoing work aimed to use supernovae
remnants to discriminate among different type Ia supernovae explosion models.
We have computed the hydrodynamic interaction of supernova ejecta with the
interstellar medium, obtaining the evolution of the density, temperature and
ionization structure of the remnant. We have used ejecta profiles obtained from
1D hydrodynamic calculations of the different explosion mechanisms that are
currently under debate. We have analyzed the best indicators that allow to
discriminate among the different explosion mechanisms, taking into account the
diversity of scenarios proposed for the presupernova evolution of the binary
system, and the uncertain amount of electron heating in collisionless shocks.


title:
Integrated Spectroscopy of Bulge Globular Clusters and Fields I. The
  Data Base and Comparison of Individual Lick Indices in Clusters and Bulge

abstract:
  We present a comprehensive spectroscopic study of the integrated light of
metal-rich Galactic globular clusters and the stellar population in the
Galactic bulge. We measure line indices which are defined by the Lick standard
system and compare index strengths of the clusters and Galactic bulge. Both
metal-rich globular clusters and the bulge are similar in most of the indices,
except for the CN index. We find a significant enhancement in the CN/<Fe> index
ratio in metal-rich globular clusters compared with the Galactic bulge. The
mean iron index <Fe> of the two metal-rich globular clusters NGC 6528 and NGC
6553 is comparable with the mean iron index of the bulge. Index ratios such as
Mgb/<Fe>, Mg2/<Fe>, Ca4227/<Fe>, and TiO/<Fe>, are comparable in both stellar
population indicating similar enhancements in individual elements which are
traced by the indices. From the globular cluster data we fully empirically
calibrate several metallicity-sensitive indices as a function of [Fe/H] and
find tightest correlations for the Mg2 index and the composite [MgFe] index. We
find that all indices show a similar behavior with galactocentric radius,
except for the Balmer series, which show a large scatter at all radii. However,
the scatter is entirely consistent with the cluster-to-cluster variations in
the horizontal branch morphology.


title:
On the anomaly of Balmer line profiles of A-type stars. Fundamental
  binary systems

abstract:
  In previous work, Gardiner et al. (1999) found evidence for a discrepancy
between the Teff obtained from Balmer lines with that from photometry and
fundamental values for A-type stars. An investigation into this anomaly is
presented using Balmer line profiles of stars in binary system with fundamental
values of both Teff and log g. A revision of the fundamental parameters for
binary systems given by Smalley & Dworetsky (1995) is also presented. The Teff
obtained by fitting Halpha and Hbeta line profiles is compared to the
fundamental values and those obtained from uvby photometry. We find that the
discrepancy found by Gardiner et al. (1999) for stars in the range 7000 K <
Teff < 9000 K is no longer evident.


title: Evolution of Deuterium, 3He and 4He in the Galaxy

abstract:
  In this work we present the predictions of the ``two-infall model''
concerning the evolution of D, 3He and 4He in the solar vicinity, as well as
their distribution along the Galactic disk. Our results show that, when
adopting detailed yields taking into account the extra-mixing process in low
and intermediate mass stars, the problem of the overproduction of 3He by the
chemical evolution models is solved. The predicted distribution of 3He along
the disk is also in agreement with the observations. We also predict the
distributions of D/H, D/O and D/N along the disk, in particular D abundances
close to the primordial value are predicted in the outer regions of the Galaxy.
The predicted D/H, D/O and D/N abundances in the local interstellar medium are
in agreement with the mean values observed by the Far Ultraviolet Spectroscopic
Explorer mission, although a large spread in the D abundance is present in the
data. Finally, by means of our chemical evolution model, we can constrain the
primordial value of the deuterium abundance, and we find a value of (D/H)_p < 4
10(-5) which implies Omega_b h^2 > 0.017, in agreement with the values from the
Cosmic Microwave Background radiation analysis. This value in turn implies a
primordial 4He abundance Y_p > 0.244.


title: ABS Methods and ABSPACK for Linear Systems and Optimization, a Review

abstract:
  ABS methods are a large class of methods, based upon the Egervary rank
reducing algebraic process, first introduced in 1984 by Abaffy, Broyden and
Spedicato for solving linear algebraic systems, and later extended to nonlinear
algebraic equations, to optimization problems and other fields; software based
upon ABS methods is now under development. Current ABS literature consists of
about 400 papers. ABS methods provide a unification of several classes of
classical algorithms and more efficient new solvers for a number of problems.
In this paper we review ABS methods for linear systems and optimization, from
both the point of view of theory and the numerical performance of ABSPACK.


title:
Natural Inflation, Planck Scale Physics and Oscillating Primordial
  Spectrum

abstract:
  In the ``natural inflation'' model, the inflaton potential is periodic. We
show that Planck scale physics may induce corrections to the inflaton
potential, which is also periodic with a greater frequency. Such high frequency
corrections produce oscillating features in the primordial fluctuation power
spectrum, which are not entirely excluded by the current observations and may
be detectable in high precision data of cosmic microwave background (CMB)
anisotropy and large scale structure (LSS) observations.


title: The metallicity of star-forming gas over cosmic time

abstract:
  A brief review concludes that there is now good overall agreement between
theoretical estimates of the energy associated with the production of the
observed metal content of the Universe and the observed extragalactic
background light. In addition the overall form of the star-formation history
over 0 < z < 5 is reasonably well constrained.
  The study of emission line gas in galaxies as a function of redshift provides
a complementary view of chemical evolution to that obtained from studies of
absorption line systems in quasar spectra. Emission line gas is more relevant
for some questions, including the confrontation with models for the chemical
evolution of our own and other galaxies, and Origins-related questions about
the formation of stars and planets. Using relatively crude diagnostic
parameters such as Pagel's R23, the increase of the metallicity of star-forming
gas with cosmic epoch can be tracked. Observations of a large sample of CFRS
galaxies at z ~ 0.8 (a look-back time of 0.5 t0 show the appearance of a
significant number of low metallicity systems amongst luminous L* galaxies.
However, overall there is only a modest change in mean metallicity compared
with the present, D log Z = -0.08 +- 0.06. These data do not support a
fading-dwarf scenario for the ``faint blue galaxies''. At z ~ 3 it is likely
that all star-forming galaxies have sub-solar metallicities. The overall
increase in the metallicity of star-forming gas with cosmic epoch matches
rather well the age-metallicity relation in the solar neighbourhood and some
recent models for the evolution of the global metallicity of gas in the
Universe.


title: Star Formation and the Initial Mass Function

abstract:
  Supersonic turbulence fragments the interstellar medium into dense sheets,
filaments, cores and large low density voids. The turbulence is driven on large
scales, probably predominantly by supernovae. The scaling properties of
supersonic turbulence are well described by a new analytical theory. The
distribution of proto-stellar core masses depends primarily on the power
spectrum of the turbulent flow, and on the jump conditions for near isothermal
shocks in a magnetized gas. For the predicted velocity power spectrum index
beta=1.74, consistent with results of numerical experiments of supersonic
turbulence as well as with Larson's velocity-size relation, one obtains by
scaling arguments a power law mass distribution of dense cores with a slope
equal to 3/(4-beta) = 1.33, consistent with the slope of the Salpeter stellar
initial mass function (IMF). Results from numerical simulations confirm this
scaling. Both the analytical model for the stellar IMF and its numerical
estimate show that turbulent fragmentation can also explain the origin of brown
dwarfs.


title: A Chandra observation of the H2O megamaser IC2560

abstract:
  A short Chandra ACIS-S observation of the Seyfert 2 galaxy IC 2560, which
hosts a luminous nuclear water megamaser, shows: 1) the X-ray emission is
extended; 2) the X-ray spectrum shows emission features in the soft (E<2 keV)
X-ray band; this is the major component of the extended emission; and 3) a very
strong (EW~3.6 keV) iron K line at 6.4 keV on a flat continuum. This last
feature clearly indicates that the X-ray source is hidden behind Compton-thick
obscuration, so that the intrinsic hard X-ray luminosity must be much higher
than observed, probably close to ~3e42 erg/s. We briefly discuss the
implications for powering of the maser emission and the central source.


title:
On the Variation of Deuterium and Oxygen Abundances in the Local
  Interstellar Medium

abstract:
  The first observations of deuterium and oxygen in the Local Interstellar
Medium (LISM) obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE)
can be used to search for local abundance variations. While the very limited
sample of these first data may be consistent with no variations, they do offer
a hint of anti-correlated variations between D/H and O/H. If confirmed by more
data (which will require independently determined, accurate HI column
densities), these hints suggest that observations of interstellar gas within a
few kpc of the solar neighborhood will reveal clear signs of the evolution of
the abundance of deuterium from there and then (the Big Bang), to here and now
(the Local Interstellar Medium of the Galaxy).


title: Dust grain properties in atmospheres of AGB stars

abstract:
  We present self-consistent dynamical models for dust driven winds of
carbon-rich AGB stars. The models are based on the coupled system of
frequency-dependent radiation hydrodynamics and time-dependent dust formation.
We investigate in detail how the wind properties of the models are influenced
by the micro-physical properties of the dust grains that enter as parameters.
The models are now at a level where it is necessary to be quantitatively
consistent when choosing the dust properties that enters as input into the
models. At our current level of sophistication the choice of dust parameters is
significant for the derived outflow velocity, the degree of condensation and
the estimated mass loss rates of the models. In the transition between models
with and without mass-loss the choice ofmicro-physical parameters turns out to
be very significant for whether a particular set of stellar parameters will
give rise to a dust-driven mass loss or not.


title: Sinking of Ne-22 in Liquid White Dwarf Interiors

abstract:
  We assess the impact of the trace element Ne-22 on the cooling and seismology
of a liquid C/O white dwarf (WD). Due to this element's neutron excess, it
sinks towards the interior as the liquid WD cools. The gravitational energy
released slows the WD's cooling by 0.5-1.6 Gyr. In addition the Ne-22 abundance
gradient changes the periods of the high radial order g-modes at the 1% level.


title: Bringing closure to microlensing mass measurement

abstract:
  Interferometers offer multiple methods for studying microlensing events and
determining the properties of the lenses. We investigate the study of
microlensing events with optical interferometers, focusing on narrow-angle
astrometry, visibility, and closure phase. After introducing the basics of
microlensing and interferometry, we derive expressions for the signals in each
of these three channels. For various forecasts of the instrumental performance,
we discuss which method provides the best means of measuring the lens angular
Einstein radius theta_E, a prerequisite for determining the lens mass. If the
upcoming generation of large-aperture, AO-corrected long baseline
interferometers (e.g. VLTI, Keck, OHANA) perform as well as expected, theta_E
may be determined with signal-to-noise greater than 10 for all bright events.
We estimate that roughly a dozen events per year will be sufficiciently bright
and have long enough durations to allow the measurement of the lens mass and
distance from the ground. We also consider the prospects for a VLTI survey of
all bright lensing events using a Fisher matrix analysis, and find that even
without individual masses, interesting constraints may be placed on the bulge
mass function, although large numbers of events would be required.


title:
Stellar population models of Lick indices with variable element
  abundance ratios

abstract:
  We provide the whole set of Lick indices from CN1 to TiO2 of Simple Stellar
Population models with, for the first time, variable element abundance ratios,
[alpha/Fe]=0.0, 0.3, 0.5, [alpha/Ca]=-0.1, 0.0, 0.2, 0.5, and [alpha/N]=-0.5,
0.0. The models cover ages between 1 and 15 Gyr, metallicities between 1/200
and 3.5 solar. Our models are free from the intrinsic alpha/Fe bias that was
imposed by the Milky Way template stars up to now, hence they reflect
well-defined alpha/Fe ratios at all metallicities. The models are calibrated
with Milky Way globular clusters for which metallicities and alpha/Fe ratios
are known from independent spectroscopy of individual stars. The metallicities
that we derive from the Lick indices Mgb and Fe5270 are in excellent agreement
with the metallicity scale by Zinn & West (1984), and we show that the latter
provides total metallicity rather than iron abundance. We can reproduce the
relatively strong CN-absorption features CN1 and CN2 of galactic globular
clusters with models in which nitrogen is enhanced by a factor three. An
enhancement of carbon, instead, would lead to serious inconsistencies with the
indices Mg1 and C24668. The calcium sensitive index Ca4227 of globular clusters
is well matched by our models with [Ca/Fe]= 0.3, including the metal-rich Bulge
clusters NGC 6528 and NGC 6553. From our alpha/Fe enhanced models we infer that
the index [MgFe] defined by Gonzalez (1993) is quite independent of alpha/Fe,
but still slightly decreases with increasing alpha/Fe. We define a slight
modification of this index that is completely independent of alpha/Fe and
serves best as a tracer of total metallicity. Searching for blue indices that
give similar information as Mgb and Fe, we find that CN1 and Fe4383 may be best
suited to estimate alpha/Fe ratios of objects at redshifts z~1. (Abridged)


title:
Collapse of a Rotating Supermassive Star to a Supermassive Black Hole:
  Analytic Determination of the Black Hole Mass and Spin

abstract:
  The collapse of a uniformaly rotating, supermassive star (SMS) to a
supermassive black hole (SMBH) has been followed recently by means of
hydrodynamic simulations in full general relativity. The initial SMS of
arbitrary mass M in these simulations rotates uniformly at the mass--shedding
limit and is marginally unstable to radial collapse. The final black hole has
mass M_h/M = 0.9 and and spin J_h/M_h^2 = 0.75, approximately. The remaining
mass goes into a disk of mass M_disk/M = 0.1, also approximately. Here we show
that these black hole and disk parameters can be calculated analytically from
the initial stellar density and angular momentum distribution. The analytic
calculation thereby corroborates and provides a simple physical explanation for
the computational discovery that SMS collapse inevitably terminates in the
simultaneous formation of a SMBH and a rather substantial ambient disk. This
disk arises even though the total spin of the progenitor star, J/M^2 = 0.97, is
safely below the Kerr limit. The calculation performed here applies to any
marginally unstable n = 3 polytrope uniformly rotating at the break--up speed,
independent of stellar mass or the source of internal pressure. It illustrates
how the black hole and disk parameters can be determined for the collapse of
other types of stars with different initial density and rotation profiles.


title:
The Spiral Structure of the Milky Way, Cosmic Rays, and Ice Age Epochs
  on Earth

abstract:
  The short term variability of the Galactic cosmic ray flux (CRF) reaching
Earth has been previously associated with variations in the global low altitude
cloud cover. This CRF variability arises from changes in the solar wind
strength. However, cosmic ray variability also arises intrinsically from
variable activity of and motion through the Milky Way. Thus, if indeed the CRF
climate connection is real, the increased CRF witnessed while crossing the
spiral arms could be responsible for a larger global cloud cover and a reduced
temperature, thereby facilitating the occurrences of ice ages. This picture has
been recently shown to be supported by various data (Shaviv, 2001). In
particular, the variable CRF recorded in Iron meteorites appears to vary
synchronously with the appearance ice ages.
  Here we expand upon the original treatment with a more thorough analysis and
more supporting evidence. In particular, we discuss the cosmic ray diffusion
model which considers the motion of the Galactic spiral arms. We also elaborate
on the structure and dynamics of the Milky Way's spiral arms. In particular, we
bring forth new argumentation using HI observations which imply that the
galactic spiral arm pattern speed appears to be that which fits the glaciation
period and the cosmic-ray flux record extracted from Iron meteorites. In
addition, we show that apparent peaks in the star formation rate history, as
deduced by several authors, coincides with particularly icy epochs, while the
long period of 1 to 2 Gyr before present, during which no glaciations are known
to have occurred, coincides with a significant paucity in the past star
formation rate.


title: The State Be7 in the Core of the Sun and the Solar Neutrino Flux

abstract:
  The exact ionization state of Be7 in the solar core is crucial for the
precise prediction of the solar B8 neutrino flux. We therefore examine the
effect of pressure ionization on the ionization state of Be7 and all elements
with 12 >= Z >= 4. We show that under the conditions prevailing in the solar
core, one has to consider the effect of the nearest neighbor on the electronic
structure of a given ion. To this goal, we first solve the Schroedinger and
then the Kohn-Sham equations for an ion immersed in a dense plasma under
conditions for which the mean interparticle distance is smaller than the Debye
radius. The question of which boundary conditions should be imposed on the wave
function is discussed, examined and found to be crucial.
  Contrary to previous estimates showing that Beryllium is partially ionized,
we find that it is fully ionized. As a consequence, the predicted rate of the
Be7 + e- reaction is reduced by 20-30%, depending on the exact solar model.
Since Be7 is a trace element, its total production is controlled by the
unchanged He4+He3 reaction rate, and its destruction is determined by the rate
of electron capture. As the latter rate decreases when the Beryllium is fully
ionized (relative to the case of partially ionized Be), the estimate for the
abundance of Be7 increases and with it the B8 neutrino flux. The increase in
phi_nu(B8) is by about 20-30%. The neutrino flux due to Be7 electron capture
remains effectively unchanged because the change in the rate is compensated for
by a change in the abundance. Hence the prediction for the ratio of phi_nu(B8)
/ phi_nu(Be7) changes as well.


title: AO Observations of Three Powerful Radio Galaxies

abstract:
  The host galaxies of powerful radio sources are ideal laboratories to study
active galactic nuclei (AGN). The galaxies themselves are among the most
massive systems in the universe, and are believed to harbor supermassive black
holes (SMBH). If large galaxies are formed in a hierarchical way by multiple
merger events, radio galaxies at low redshift represent the end-products of
this process. However, it is not clear why some of these massive ellipticals
have associated radio emission, while others do not. Both are thought to
contain SMBHs, with masses proportional to the total luminous mass in the
bulge. It either implies every SMBH has recurrent radio-loud phases, and the
radio-quiet galaxies happen to be in the "low" state, or that the radio galaxy
nuclei are physically different from radio-quiet ones, i.e. by having a more
massive SMBH for a given bulge mass.
  Here we present the first results from our adaptive optics imaging and
spectroscopy pilot program on three nearby powerful radio galaxies. Initiating
a larger, more systematic AO survey of radio galaxies (preferentially with
Laser Guide Star equipped AO systems) has the potential of furthering our
understanding of the physical properties of radio sources, their triggering,
and their subsequent evolution.


title: Orbital and Super-Orbital Periods of 1E 1740.7-2942 and GRS 1758-258

abstract:
  Five years of Rossi X-ray Timing Explorer (RXTE) observations of the Galactic
black-hole candidates 1E 1740.7-2942 and GRS 1758-258 show a periodic
modulation with amplitude 3-4% in each source at 12.73 +/- 0.05 dy and 18.45
+/- 0.10 dy, respectively. We interpret the modulations as orbital, suggesting
that the objects have red-giant companions. Combining the RXTE data with
earlier data (Zhang, Harmon & Liang 1997) from the Burst and Transient Source
Experiment on the Compton Gamma-Ray Observatory, we find a long period or
quasi-period of about 600 dy in 1E 1740.7-2942, and a suggestion of a similar
600-dy period in GRS 1758-258. These timescales are longer than any yet found
for either precessing systems like Her X-1 and SS 433 or binaries like LMC X-3
and Cyg X-1 with more irregular long periods.


title: Mg II & C IV Kinematics vs. Stellar Kinematics in Galaxies

abstract:
  Comparisons of the kinematics of Mg II absorbing gas and the stellar rotation
curves in 0.5 < z < 1.0 spiral galaxies suggests that, at least in some cases,
the extended gaseous envelopes may be dynamically coupled to the stellar
matter. A strong correlation exists between the overall kinematic spread of Mg
II absorbing gas and C IV absorption strength, and therefore kinematics of the
higher-ionization gas. Taken together, the data may suggest a "halo/disk
connection" between z~1 galaxies and their extended gaseous envelopes. Though
the number of galaxies in our sample are few, there are no clear examples that
suggest the gas is accreting/infalling isotropically about the galaxies from
the intergalactic medium.


title:
Gamma Ray Bursts from delayed collapse of neutron stars to quark matter
  stars

abstract:
  We propose a model to explain how a Gamma Rays Burst can take place days or
years after a supernova explosion. Our model is based on the conversion of a
pure hadronic star (neutron star) into a star made at least in part of
deconfined quark matter. The conversion process can be delayed if the surface
tension at the interface between hadronic and deconfined-quark-matter phases is
taken into account. The nucleation time (i.e. the time to form a critical-size
drop of quark matter) can be extremely long if the mass of the star is small.
Via mass accretion the nucleation time can be dramaticaly reduced and the star
is finally converted into the stable configuration. A huge amount of energy, of
the order of 10$^{52}$--10$^{53}$ erg, is released during the conversion
process and can produce a powerful Gamma Ray Burst. The delay between the
supernova explosion generating the metastable neutron star and the new collapse
can explain the delay proposed in GRB990705 and in GRB011211.


title: New optical filamentary structures in Pegasus

abstract:
  Deep Halpha+[N II] CCD images have been obtained in the area of the Pegasus
Constellation. The resulting mosaic covers an extent of ~7.5 degr x ~8.5 degr
and filamentary and diffuse emission is discovered. Several long filaments (up
to ~1 degr) are found within the field, while diffuse emission is present
mainly in the central and northern areas. The filaments show variations in the
intensity along their extent suggesting inhomogeneous interstellar clouds.
Faint soft X-ray emission is also detected in the ROSAT All-Sky Survey. It is
mainly concentrated in the central areas of our field and overlaps the optical
emission. The low ionization images of [S II] of selected areas mainly show
faint diffuse emission, while in the medium ionization images of [O III]
diffuse and faint filamentary structures are present. Spectrophotometric
observations have been performed on the brightest filaments and indicate
emission from photoionized or shock-heated gas. The sulfur line ratios indicate
electron densities below ~600 cm^{-3}, while the absolute Halpha emission lies
in the range of 1.1 - 8.8 x 10^{-17} erg s^{-1} cm^{-2} arcsec^{-2}. The
detected optical line emission could be part of a single or multiple supernova
explosions.


title: A large Wolf-Rayet population in NGC300 uncovered by VLT-FORS2

abstract:
  We have detected 58 Wolf-Rayet candidates in the central region of the nearby
spiral galaxy NGC 300, based on deep VLT-FORS2 narrow-band imaging. Our survey
is close to complete except for heavily reddened WR stars. Of the objects in
our list, 16 stars were already spectroscopically confirmed as WR stars by
Schild & Testor and Breysacher et al., to which 4 stars are added using low
resolution FORS2 datasets. The WR population of NGC300 now totals 60,a
threefold increase over previous surveys, with WC/WN>1/3, in reasonable
agreement with Local Group galaxies for a moderately sub-solar metallicity. We
also discuss the WR surface density in the central region of NGC 300. Finally,
analyses are presented for two apparently single WC stars - #29 (alias WR3,
WC5) and #48 (alias WR13, WC4) located close to the nucleus, and at a
deprojected radius of 2.5 kpc, respectively. These are among the first models
of WR stars in galaxies beyond the Local Group, and are compared with early WC
stars in our Galaxy and LMC.


title:
Comparing the old Stellar Population in Globulars and Dwarf Galaxies:
  The Cases of Phoenix and Leo A

abstract:
  Due to their star formation history (SFH), the stellar population in Dwarf
Galaxies (DG) is likely to have a metallicity spread which is best traced by
the morphology of the Red Giant Branch (RGB). We probe here a purely empirical
approach aimed at estimating average metallicity (Z) and Z spread by comparing
the Color-Magnitude Diagrams (CMD) of galactic Globular Clusters (GCs) with
those of two DGs: Leo A (HST data) and Phoe (VLT Fors2 data).


title: The Geometry of Resonant Signatures in Debris Disks with Planets

abstract:
  Using simple geometrical arguments, we paint an overview of the variety of
resonant structures a single planet with moderate eccentricity (e < ~0.6) can
create in a dynamically cold, optically thin dust disk. This overview may serve
as a key for interpreting images of perturbed debris disks and inferring the
dynamical properties of the planets responsible for the perturbations. We
compare the resonant geometries found in the solar system dust cloud with
observations of dust clouds around Vega and other stars and we discuss a new
model for the asymmetries in the Epsilon Eridani cloud.


title: Missing baryons and the soft X-ray background

abstract:
  The X-ray background intensity around Lick count galaxies and rich clusters
of galaxies is investigated in three ROSAT energy bands. It is found that the
X-ray enhancements surrounding concentrations of galaxies exhibit significantly
softer spectrum than the standard cluster emission and the average
extragalactic background. The diffuse soft emission accompanying the galaxies
is consistent with the thermal emission of the hot gas postulated first by the
Cen & Ostriker hydrodynamic simulations. Our estimates of the gas temperature -
although subject to large uncertainties - averaged over several Mpc scales are
below 1 keV, which is substantially below the temperature of the intra-cluster
gas, but consistent with temperatures predicted for the local intergalactic
medium. It is pointed out that the planned ROSITA mission would be essential
for our understanding of the diffuse thermal component of the background.


title: Gravitational Lensing at Millimeter Wavelengths

abstract:
  With today's millimeter and submillimeter instruments observers use
gravitational lensing mostly as a tool to boost the sensitivity when observing
distant objects. This is evident through the dominance of gravitationally
lensed objects among those detected in CO rotational lines at z>1. It is also
evident in the use of lensing magnification by galaxy clusters in order to
reach faint submm/mm continuum sources. There are, however, a few cases where
millimeter lines have been directly involved in understanding lensing
configurations. Future mm/submm instruments, such as the ALMA interferometer,
will have both the sensitivity and the angular resolution to allow detailed
observations of gravitational lenses. The almost constant sensitivity to dust
emission over the redshift range z=1-10 means that the likelihood for strong
lensing of dust continuum sources is much higher than for optically selected
sources. A large number of new strong lenses are therefore likely to be
discovered with ALMA, allowing a direct assessment of cosmological parameters
through lens statistics. Combined with an angular resolution <0.1", ALMA will
also be efficient for probing the gravitational potential of galaxy clusters,
where we will be able to study both the sources and the lenses themselves, free
of obscuration and extinction corrections, derive rotation curves for the
lenses, their orientation and, thus, greatly constrain lens models.


title: Black holes and gamma ray bursts: background for the theoretical model

abstract:
  The idea that the vacuum polarization process occurring during gravitational
collapse to a black hole endowed with electromagnetic structure (EMBH) could be
the origin of gamma ray bursts (GRBs) is further developed. EMBHs in the range
3.2 -- 10$^6$ solar masses are considered. The formation of such an EMBH, the
extraction of its mass-energy by reversible transformations and the expansion
of the pair-electromagnetic pulse (PEM pulse) are all examined within general
relativity. The PEM pulse is shown to accelerate particles to speeds with
Lorentz gamma factors way beyond any existing experiment on Earth. Details of
the expected burst structures and other observable properties are examined.


title: Ex-nihilo: Obstacles Surrounding Teaching the Standard Model

abstract:
  The model of the Big Bang is an integral part of the national curriculum for
England. Previous work (e.g. Baxter 1989) has shown that pupils often come into
education with many and varied prior misconceptions emanating from both
internal and external sources. Whilst virtually all of these misconceptions can
be remedied, there will remain (by its very nature) the obstacle of ex-nihilo,
as characterised by the question `how do you get something from nothing?' There
are two origins of this obstacle: conceptual (i.e. knowledge-based) and
cultural (e.g. deeply held religious viewpoints). The article shows how the
citizenship section of the national curriculum, coming `online' in England from
September 2002, presents a new opportunity for exploiting these.


title: Molecular gas in the 3-ringed Seyfert/Liner galaxy NGC 7217

abstract:
  We present CO(1-0) and CO(2-1) maps of the Seyfert galaxy NGC 7217, obtained
with the IRAM interferometer, at 3" and 1.5" resolution respectively. The
nuclear ring (at r=12"=0.8kpc) is predominant in the CO maps, with a remarkable
surface density gradient between the depleted region inside the ring and the
inner border of the ring. The CO nuclear ring is significantly broader
(500-600pc) than the dust lane ring. The CO(2-1)/CO(1-0) ratio is around 1,
typical of optically thick gas with high density. The overall morphology of the
ring is quite circular, with no evidence of non-circular velocities. In the
CO(2-1) map, a central concentration might be associated with the circumnuclear
ring of ionised gas detected inside r=3" and interpreted as a polar ring by
Sil'chenko and Afanasiev (2000). Our interpretation is more in terms of a
bar/spiral structure, in the same plane as the global galaxy but affected by
non-circular motions, which results in a characteristic S-shape of the isovels.
This nuclear bar/spiral structure, clearly seen in a V-I HST colour image, is
essentially gaseous and might be explained with acoustic waves.


title: Molecular gas in the double-barred Seyfert 2 galaxy NGC 5728

abstract:
  We present CO(1-0) and CO(2-1) maps of the Seyfert galaxy NGC 5728. Although
a stellar nuclear bar structure is clearly identified in the near-infrared
images in the central 10", inside the ring identified as the ILR of the primary
bar, there is no nuclear bar structure in the molecular gas. Instead, the CO
emission reveals an elongated structure, 15" in length, beginning at the
nucleus (defined by the radio center) aligned with the jet/ionisation cone, at
a PA of 127 degrees. This morphology, not frequently observed in Seyfert
galaxies, may be interpreted in terms of enhanced CO excitation along the walls
of the cone. Kinematical perturbations along the cone support this scenario. At
larger-scale, CO emission is tracing the primary bar, and outer ring structure.
The total molecular mass, estimated from the CO emission, is M(H2) = 3.1 10^9
Msun.


title: Search for the optical counterpart of the nearby pulsar J0108-1431

abstract:
  We present the results of first deep optical observations of the field of the
old ($\sim 10^8$ yr), nearby, isolated pulsar J0108-1431, in an attempt to
detect its optical counterpart. The observations were performed using the FORS1
instrument at the focus of the European Southern Observatory Antu Telescope of
the VLT. Observations with the Australia Telescope Compact Array (ATCA) were
made to determine an accurate position for the radio pulsar at the current
epoch. The imaging data, obtained in the V, B, and U passbands reveal no
counterpart at the revised radio position down to $V \simeq 28$, $B\simeq 28.6$
and $U \simeq 26.4$. For a distance of 130 pc, estimated from the pulsar's
dispersion measure, our constraints on the optical flux put an upper limit of
$T=4.5\times 10^4$ K for the surface temperature of the neutron star, assuming
a stellar radius $R_\infty=13$ km. Our new radio position allows us to place an
upper limit on the pulsar proper motion of 82 mas yr$^{-1}$ which, for d=130
pc, implies a transverse velocity $\la 50$ km sec$^{-1}$.


title:
On the origin of the torus and jet-like structures in the centre of Crab
  Nebula

abstract:
  The formation of the toroidal and jet-like structures in the central part of
the Crab Nebula is explained in the framework of Kennel & Coroniti theory. The
only new element introduced by us in this theory is the initial anisotropy of
the energy flux in the wind. We estimate the X-ray surface brightness of the
Crab Nebula from the region of interaction of this wind with the interstellar
medium and compare it with observations.


title:
Data analysis methods for XMM-Newton observations of extended sources.
  Application to bright massive clusters of galaxies at z=0.2

abstract:
  In this paper, a review is given of methods useful for XMM-Newton EPIC data
analysis of extended sources, along with some applications to a bright massive
cluster of galaxies at z=0.2, Abell 209. This may constitute an introduction to
that kind of advanced analysis, complementing cookbooks that can be found over
the internet, the XMM-Newton EPIC calibration status document (Kirsch, 2002),
and the data analysis workshops organised in VILSPA, which were only dedicated
so far to point sources analysis. In addition, new spectro-imaging techniques
are proposed, in order to measure for instance the intracluster medium mass and
temperature profiles, or even maps.


title:
Notch Filter Masks: Practical Image Masks for Planet-Finding
  Coronagraphs

abstract:
  An ideal coronagraph with a band-limited image mask can efficiently image
off-axis sources while removing identically all of the light from an on-axis
source. However, strict mask construction tolerances limit the utility of this
technique for directly imaging extrasolar terrestrial planets. We present a
variation on the basic band-limited mask design--a family of ``notch filter''
masks--that mitigates this problem. These robust and trivially achromatic masks
can be easily manufactured by cutting holes in opaque material.


title: A Flared, Orbiting, Dusty Disk Around HD 233517

abstract:
  We find that the infrared excess around HD 233517, a first ascent red giant,
can be naturally explained if the star possesses an orbiting, flared dusty
disk. We estimate that the outer radius of this disk is 45 AU and that the
total mass within the disk is about 0.01 the mass of the Sun. We speculate that
this disk is the result of the engulfment of a low mass companion star that
occurred when HD 233517 became a red giant.


title: Inflation at the Edge

abstract:
  Recent results from cosmic microwave background (CMB) experiments verify
several of the predictions of inflation, while ruling out a number of
alternative structure-formation scenarios. Given the successes of the theory,
the obvious next step is to press ahead and test inflation to the edge of all
our current and forthcoming observational abilities. According to the
inflationary paradigm, galaxies and their large-scale distribution in the
Universe are remnants of inflation and can thus be studied to learn more about
inflation in the same way that experimental particle physicists study the
remnants of high-energy collisions. Here I discuss how studies of galactic
substructure, galaxies, clusters, large-scale structure, and the CMB, may be
used to learn more about inflation.


title: Everpresent Lambda

abstract:
  A variety of observations indicate that the universe is dominated by dark
energy with negative pressure, one possibility for which is a cosmological
constant. If the dark energy is a cosmological constant, a fundamental question
is: Why has it become relevant at so late an epoch, making today the only time
in the history of the universe at which the cosmological constant is of order
the ambient density. We explore an answer to this question drawing on ideas
from unimodular gravity, which predicts fluctuations in the cosmological
constant, and causal set theory, which predicts the magnitude of these
fluctuations. The resulting ansatz yields a fluctuating cosmological
``constant'' which is always of order the ambient density.


title: Probing Disk Accretion in Young Brown Dwarfs

abstract:
  We present high-resolution optical spectra of 15 objects near or below the
sub-stellar limit in the Upper Scorpius and $\rho$ Ophiuchus star-forming
regions. These spectra, obtained with the HIRES instrument on the Keck I
telescope, are used to investigate disk accretion, rotation and activity in
young very low mass objects. We report the detection of a broad, asymmetric
H$\alpha$ emission line in the $\rho$ Oph source GY 5 which is also known to
harbor mid-infrared excess, consistent with the presence of an accreting disk.
The H$\alpha$ profiles of the Upper Sco objects suggest little or no on-going
accretion. Our results imply that if most brown dwarfs are born with disks,
their accretion rates decrease rapidly, at timescales comparable to or smaller
than those for T Tauri disks. The Upper Sco brown dwarfs appear to be rotating
faster than their somewhat younger counterparts in Taurus, consistent with
spin-up due to contraction following disk unlocking. The H$\alpha$ activity is
comparable to saturated activity levels in field M dwarfs with similar spectral
type and rotation rates. Comparison of our data with published (albeit
lower-resolution) spectra of a few of the same objects from other epochs
suggests possible variability in accretion/activity indicators.


title: Dynamical derivation of Bode's law

abstract:
  In a planetary or satellite system, idealized as n small bodies in initially
coplanar, concentric orbits around a large central body, obeying Newtonian
point-particle mechanics, resonant perturbations will cause dynamical evolution
of the orbital radii except under highly specific mutual relationships, here
derived analytically apparently for the first time. In particular, the most
stable situation is achieved (in this idealized model) only when each planetary
orbit is roughly twice as far from the Sun as the preceding one, as observed
empirically already by Titius (1766) and Bode (1778) and used in both the
discoveries of Uranus (1781) and the Asteroid Belt (1801). ETC.


title: An Extraordinary Scattered Broad Emission Line in a Type 2 QSO

abstract:
  An infrared-selected, narrow-line QSO has been found to exhibit an
extraordinarily broad Halpha emission line in polarized light. Both the extreme
width (35,000 km/sec full-width at zero intensity) and 3,000 km/sec redshift of
the line centroid with respect to the systemic velocity suggest emission in a
deep gravitational potential. An extremely red polarized continuum and partial
scattering of the narrow lines at a position angle common to the broad-line
emission imply extensive obscuration, with few unimpeded lines of sight to the
nucleus.


title: Observational Properties of Primordial Stellar Populations

abstract:
  We present the first results of a study of the expected properties of the
first stellar generations in the Universe. In particular, we consider and
discuss a series of properties that, on the basis of the emission from
associated HII regions, permit one to discern {\it bona fide} primeval stellar
generations from the ones formed after pollution from supernova explosions. The
expected performance of NGST for the study and the characterization of
primordial sources is also discussed.


title: How Do Galaxies Get Their Gas?

abstract:
  Not the way one might have thought. In hydrodynamic simulations of galaxy
formation, some gas follows the traditionally envisioned route, shock heating
to the halo virial temperature before cooling to the much lower temperature of
the neutral ISM. But most gas enters galaxies without ever heating close to the
virial temperature, gaining thermal energy from weak shocks and adiabatic
compression, and radiating it just as quickly. This ``cold mode'' accretion is
channeled along filaments, while the conventional, ``hot mode'' accretion is
quasi-spherical. Cold mode accretion dominates high redshift growth by a
substantial factor, while at z<1 the overall accretion rate declines and hot
mode accretion has greater relative importance. The decline of the cosmic star
formation rate at low z is driven largely by geometry, as the typical cross
section of filaments begins to exceed that of the galaxies at their
intersections.


title: The Radial Structure of SNR N103B

abstract:
  We report on the results from a Chandra ACIS observation of the young,
compact, supernova remnant N103B. The unprecedented spatial resolution of
Chandra reveals sub-arcsecond structure, both in the brightness and in spectral
variations. Underlying these small-scale variations is a surprisingly simple
radial structure in the equivalent widths of the strong Si and S emission
lines. We investigate these radial variations through spatially resolved
spectroscopy using a plane-parallel, non-equilibrium ionization model with
multiple components. The majority of the emission arises from components with a
temperature of 1 keV: a fully ionized hydrogen component; a high ionization
timescale (n_e*t > 10^12 s cm^-3) component containing Si, S, Ar, Ca, and Fe;
and a low ionization timescale (n_e*t ~ 10^{11} s cm^-3) O, Ne, and Mg
component. To reproduce the strong Fe Kalpha line, it is necessary to include
additional Fe in a hot (> 2 keV), low ionization (n_e*t ~ 10^10.8 s cm^-3)
component. This hot Fe may be in the form of hot Fe bubbles, formed in the
radioactive decay of clumps of 56Ni. We find no radial variation in the
ionization timescales or temperatures of the various components. Rather, the Si
and S equivalent widths increase at large radii because these lines, as well as
those of Ar and Ca, are formed in a shell occupying the outer half of the
remnant. A shell of hot Fe is located interior to this, but there is a large
region of overlap between these two shells. In the inner 30% of the remnant,
there is a core of cooler, 1 keV Fe. We find that the distribution of the
ejecta and the yields of the intermediate mass species are consistent with
model prediction for Type Ia events.