title: Black hole growth and activity in a LambdaCDM Universe

abstract:
  (abridged) The observed properties of supermassive black holes suggest a
fundamental link between their assembly and the formation of their host
spheroids. We model the growth and activity of black holes in galaxies using
LambdaCDM cosmological hydrodynamic simulations by following the evolution of
the baryonic mass component in galaxy potential wells. We find that the
observed steep relation between black hole mass and spheroid velocity
dispersion, M_BH propto \sigma^4, is reproduced if the gas mass in bulges is
linearly proportional to the black hole mass. In this model, black hole growth
saturates because of the competition with star-formation and feedback, both of
which determine the gas fraction available for accretion. Unless other
processes also operate, we predict that the M_BH-sigma$ relation is not set in
primordial structures but is fully established at low redshifts, $z \approxlt
2$, and is shallower at earlier times. We find that that central black hole
masses are related to their dark matter halos simply via M_BH ~ M_DM^4/3. We
assume that galaxies undergo a quasar phase with a typical lifetime, t_Q ~
2\times 10^7 yr and show that star-formation regulated depletion of gas in
spheroids can explain the decrease of the quasar population at redshift z<3 in
the optical blue band. However, with the simplest assumption of a redshift
independent quasar lifetime, the model overpredicts optical quasar numbers at
high redshifts although it yields the observed evolution of number density of
X-ray quasars over the redshift range 1 < z< 6. Finally, we find that the
majority of black hole mass is assembled in galaxies by z ~ 3 and that the
black hole accretion rate density peaks in rough correspondence to the star
formation rate density at z ~ 4-5.


title: HST/STIS Spectroscopy of the Intermediate Polar EX Hydrae

abstract:
  We present the results of our analysis of six orbits of HST/STIS time-tagged
spectroscopy of the intermediate polar, EX Hydrae. The high time and wavelength
resolution of the HST/STIS spectra provided an excellent opportunity to study
the UV properties of EX Hya. Measurements of the continuum and emission line
fluxes corroborate earlier studies that show that the emission line fluxes are
modulated more strongly than the continuum flux and originate from the
accretion curtains, while the continuum flux originates from the white dwarf
photosphere. The measured K amplitude of the narrow emission line radial
velocity curve is used to calculate a white dwarf mass of 0.91+/-0.05 M_sun.
Synthetic white dwarf photosphere and accretion disk spectral models are used
to further refine the white dwarf and accretion disk properties. Using the
spectral models, it is determined that EX Hya has a white dwarf of mass 0.9
M_sun, T=23000 K, an accretion disk truncated at 2.5 R_WD, and is at a distance
of 60 pc.


title:
The iron line in MCG-6-30-15 from XMM-Newton: evidence for gravitational
  light-bending?

abstract:
  The lack of variability of the broad iron line seen in the Seyfert 1 galaxy
MCG-6-30-15 is studied using the EPIC pn data obtained from a 2001 observation
of 325 ks, during which the count rate from the source varied by a factor of 5.
The spectrum of 80 ks of data from when the source was bright, using the the
lowest 10 ks as background, is well fitted over the 3-10 keV band with a simple
power-law of photon index Gamma=2.11. The source spectrum can therefore be
decomposed into an approximately constant component, containing a strong iron
emission line, and a variable power law component. Assuming that the power-law
continuum extends down to 0.5 keV enables us to deduce the absorption acting on
the nucleus. A simple model involving Galactic absorption and 2 photoelectric
edges (at 0.72 and 0.86 keV) is adequate for the EPIC spectrum above 1 keV. It
still gives a fair representation of the spectrum at lower energies where
absorption lines, UTAs etc are expected. Applying the absorption model to the
low flux spectrum enables us to characterize it as reflection-dominated with
iron about 3 times Solar. Fitting this model, with an additional power-law
continuum, to 32 x 10 ks spectra of the whole observation reveals that Gamma
lies mostly between 2 and 2.3 and the normalization of the reflection-dominated
component varies by up to 25 per cent. The breadth of the iron line suggests
that most of the illumination originates from about 2 gravitational radii.
Gravitational light bending will be very strong there, causing the observed
continuum to be a strong function of the source height and much of the
continuum radiation to return to the disk. Together these effects can explain
the otherwise puzzling disconnectedness of the continuum and reflection
components of MCG-6-30-15.


title: Gap Formation by Planets in Turbulent Protostellar Disks

abstract:
  The processes of planet formation and migration depend intimately on the
interaction between planetesimals and the gaseous disks in which they form. The
formation of gaps in the disk can severely limit the mass of the planet and its
migration toward the protostar. We investigate the process of gap formation
through magnetohydrodynamic simulations in which internal stress arises
self-consistently from turbulence generated by the magnetorotational
instability. The simulations investigate three different planetary masses and
two disk temperatures to bracket the tidal (thermal) and viscous gap opening
conditions. The results are in general qualitative agreement with previous
simulations of gap formation, but show significant differences. In the presence
of MHD turbulence, the gaps produced are shallower and asymmetrically wider
than those produced with pure hydrodynamics. The rate of gap formation is also
slowed, with accretion occurring across the developing gap. Viscous
hydrodynamics does not adequately describe the evolution, however, because
planets capable of producing gaps also may be capable of affecting the level
MHD turbulence in different regions of the disk.


title: Statistical Isotropy of CMB and Cosmic Topology

abstract:
  The breakdown of statistical homogeneity and isotropy of cosmic perturbations
is a generic feature of ultra large scale structure of the cosmos, in
particular, of non trivial cosmic topology. The statistical isotropy (SI) of
the Cosmic Microwave Background temperature fluctuations (CMB anisotropy) is
sensitive to this breakdown on largest scales comparable to, and even beyond
the cosmic horizon. We study a set of measures, $\kappa_\ell$ ($\ell=1,2,3,
>...$) which for non-zero values indicate and quantify statistical isotropy
violations in a CMB map. The main goal here is to interpret the $\kappa_\ell$
spectrum and relate it to characteristic patterns in the correlation function
of CMB anisotropy arising from cosmic topology. We numerically compute the
predicted $\kappa_\ell$ spectrum for CMB anisotropy in flat torus universe
models. The essential features are captured in the leading order approximation
to the correlation function where $\kappa_\ell$ can be calculated analytically.
The $\kappa_\ell$ spectrum is shown to reflect the number, importance and
relative orientation of principal directions in the CMB correlation dictated by
the shape of the Dirichlet domain (DD) of the compact space and its size
relative to cosmic horizon. Hence, besides detecting cosmic topology,
$\kappa_\ell$ can discriminate between different topology of the universe
complementing ongoing search for cosmic topology in CMB anisotropy data.


title: Simulations of unstable gaseous disks and the origin of giant planets

abstract:
  We study the evolution of cold, gravitationally unstable protoplanetary
gaseous disks performing 3D SPH simulations with up to a million particles on
large parallel machines. We show that self-gravitating protoplanets can form in
disks with initial $Q_{min} \sim 1.4$ provided that disks are evolved with a
locally isothermal equation of state until localized regions reach a
sufficiently high density. Lower resolution simulations carried out for as long
as a thousand years show that systems of giant protoplanets with masses and
orbits comparable to those of the observed extrasolar planets arise naturally.


title: Chandra Observations of QSO 2237+0305

abstract:
  We present the observations of the gravitationally lensed system QSO
2237+0305 performed with the Chandra X-ray Observatory on 2000 Sept. 6, and on
2001 Dec. 8 for 30.3 ks and 9.5 ks, respectively. Imaging analysis resolves the
four X-ray images of the Einstein Cross. A possible fifth image is detected;
however, this detection less certain. Fits to the combined spectrum of all
images of the Einstein Cross assuming a simple power law with Galactic and
intervening absorption at the lensing galaxy yield a photon index of
1.90(+0.05,-0.05). For the first observation, this spectral model yields a
0.4-8.0 keV X-ray flux of 4.6e-13 erg cm-2 s-1 and a 0.4-8.0 keV lensed
luminosity of 1.0e46 erg s-1. The source exhibits variability both over long
and short time scales. The X-ray flux has dropped by 20% between the two
observations, and the K-S test showed that image A is variable at the 97%
confidence level within the first observation. Furthermore, a possible
time-delay of 2.7(+0.5,-0.9) hours between images A and B with image A leading
is detected in the first observation. The X-ray flux ratios of the images are
consistent with the optical flux ratios which are affected by microlensing
suggesting that the X-ray emission is also microlensed. A comparison between
our measured column densities and those inferred from extinction measurements
suggests a higher dust-to-gas ratio in the lensing galaxy than the average
value of our Galaxy. Finally, we report the detection at the 99.99% confidence
level of a broad emission feature near the redshifted energy of the Fe K\alpha
line in only the spectrum of image A. The rest frame energy, width, and
equivalent width of this feature are E = 5.7(+0.2,-0.3) keV, sigma =
0.87(+0.30,-0.15) keV, and EW = 1200(+300,-200) eV, respectively.


title:
Electromagnetic Fluctuations during Fast Reconnection in a Laboratory
  Plasma

abstract:
  Clear evidence for a positive correlation is established between the
magnitude of magnetic fluctuations in the lower-hybrid frequency range and
enhancement of reconnection rates in a well-controlled laboratory plasma. The
fluctuations belong to the right-hand polarized whistler wave branch,
propagating obliquely to the reconnecting magnetic field, with a phase velocity
comparable to the relative drift velocity between electrons and ions. The short
coherence length and large variation along the propagation direction indicate
their strongly nonlinear nature in three dimensions.


title: RX J0944.5+0357: A Probable Intermediate Polar

abstract:
  From optical photometry the cataclysmic variable RX J0944.5+0357 is shown to
have a double-peaked pulse profile with a period of ~2160 s. The two peaks vary
rapidly in relative amplitude. Often most of the optical power is concentrated
in the first harmonic of the 2160s modulation: RX J0944.5+0357 therefore
probably belongs to the relatively rare class of two-pole accreting
intermediate polars exemplified by YY Dra and V405 Aur.


title: Multiple UHECR Events from Galactic hadron jets

abstract:
  We propose a new observational test of top-down source models for the
ultra-high-energy cosmic-rays (UHECRs), based on the simultaneous observation
of two or more photons from the same Galactic hadron jet. We derive a general
formula allowing one to calculate the probability of detecting such `multiple
events', for any particular top-down model, once the physical parameters of the
associated hadron jets are known. We then apply our results to a generic
top-down model involving the decay of a supermassive particle, and show that
under reasonable assumptions the next-generation UHECR detectors would be able
to detect multiple events on a timescale of a few years, depending on the mass
of the top-down progenitor. Either the observation or the non-observation of
such events will provide constraints on the UHECR top-down models and/or the
physics of hadronization at ultra-high energy.


title: Galactic Halo Stars in Phase Space :A Hint of Satellite Accretion?

abstract:
  The present day chemical and dynamical properties of the Milky Way bear the
imprint of the Galaxy's formation and evolutionary history. One of the most
enduring and critical debates surrounding Galactic evolution is that regarding
the competition between ``satellite accretion'' and ``monolithic collapse'';
the apparent strong correlation between orbital eccentricity and metallicity of
halo stars was originally used as supporting evidence for the latter. While
modern-day unbiased samples no longer support the claims for a significant
correlation, recent evidence has been presented by Chiba & Beers
(2000,AJ,119,2843) for the existence of a minor population of high-eccentricity
metal-deficient halo stars. It has been suggested that these stars represent
the signature of a rapid (if minor) collapse phase in the Galaxy's history.
Employing velocity- and integrals of motion-phase space projections of these
stars, coupled with a series of N-body/Smoothed Particle Hydrodynamic (SPH)
chemodynamical simulations, we suggest an alternative mechanism for creating
such stars may be the recent accretion of a polar orbit dwarf galaxy.


title:
The Host Galaxies of Optical Bright QSOs: Molecular Gas in Z < 0.1
  PG-QSOs

abstract:
  We present results of a CO(1-0) line survey in a complete sample of 12 low
redshift (Z < 0.1), optically bright QSOs (PG QSOs with M_B < -23 mag). Six new
CO detections are reported here at levels exceeding I_CO ~2 Jy km/s. Combined
with three previously reported detections, we find that 9 of the 12 QSOs have
abundant, dense ISMs characteristic of late type galaxies. In all 9 of the
detected QSOs, the derived molecular gas masses are M(H2) > 1.0e9 M_solar, with
the most massive being 1e10 M_solar ~(PG 0050+124 -- I Zw 1). In the three
sources not yet detected in CO, the upper limits on the gas masses are ~ 1e9
M_solar and thus we cannot rule out abundant ISMs even in these objects. Since
our sample was chosen entirely on the basis of low redshift and optical
luminosity (and not selected for strong infrared emission), we conclude that
the majority of luminous, low redshift QSOs have gas-rich host galaxies and
therefore can not be normal elliptical galaxies.


title:
NE2001. II. Using Radio Propagation Data to Construct a Model for the
  Galactic Distribution of Free Electrons

abstract:
  In Paper I we present a new model for the Galactic distribution of free
electrons. In this paper we describe the input data and methodology for
determining the structure and parameters of the model. Tables of the input data
are provided and several figures are used to demonstrate why particular
Galactic structures are needed. We identify lines of sight on which discrete
regions either enhance or diminish the dispersion or the scattering. Most do
not coincide with known \ion{H}{2} regions or supershells, most likely because
the enhancements correspond to column densities smaller than detection
thresholds for the emission measure in recombination-line surveys.


title:
Observations of Galactic and Extra-galactic Sources From the BOOMERANG
  and SEST Telescopes

abstract:
  We present millimeter-wave observations of three extra-galactic and six
Galactic sources in the Southern sky. Observations were made at 90, 150, 240
and 400 GHz with resolutions of 18, 10, 14 and 12 arcmin respectively during
the 1998 Antarctic long duration balloon flight of BOOMERANG. Observations were
also made with the SEST telescope, at 90 and 150 GHz with resolutions of 57 and
35 arcsec respectively. These observations can be used for calibrations of
Cosmic Microwave Background (CMB) experiments as well as an understanding of
the physical processes of the sources.


title: A Resolution Requirement for Disk Simulations Modeling Collapse

abstract:
  The accurate simulation of collapsed objects requires that a huge range of
spatial scales be well resolved if the result is not to be contaminated by
numerically induced fragmentation. In this context, `insufficient resolution'
means comparable to the local instability wavelength in the system. I define a
minimum resolution criterion for simulations of disk systems, using the
critical wavelength appropriate for disks.


title:
Recovering the Initial Condition of our Local Universe from NOG and PSCz
  Catalogues

abstract:
  We apply the ZTRACE algorithm to the optical NOG and infra-red PSCz galaxy
catalogues to reconstruct the pattern of primordial fluctuations that have
generated our local Universe. We check that the density fields traced by the
two catalogues are well correlated, and consistent with a linear relation
(either in $\delta$ or in log(1+$\delta$)) with relative bias (of NOG with
respect to PSCz) b_rel = 1.1 $\pm$ 0.1. The relative bias relation is used to
fill the optical zone of avoidance at |b| < 20$^\circ$ using the PSCz galaxy
density field. We perform extensive testing on simulated galaxy catalogues to
optimize the reconstruction. The quality of the reconstruction is predicted to
be good at large scales, up to a limiting wavenumber k_lim $\simeq$ 0.4 h/Mpc
beyond which all information is lost. We find that the improvement due to the
denser sampling of the optical catalogue is compensated by the uncertainties
connected to the larger zone of avoidance. The initial conditions reconstructed
from the NOG catalogue are found (analogously to those from the PSCz) to be
consistent with Gaussian paradigm. We use the reconstructions to produce sets
of initial conditions ready to be used for constrained simulations of our local
Universe.


title: Spectral analysis of sdB stars from the Hamburg Quasar Survey

abstract:
  We present the results of a spectral analysis of a large sample of subdwarf B
stars selected from follow-up observations of candidates from the Hamburg
Quasar Survey. Fundamental parameters (effective temperature, gravity, and
helium abundance) were determined by matching synthetic line profiles
calculated from model atmospheres to all hydrogen and helium absorption lines
present in the observed optical spectra. The derived helium abundances are
compared with the atmospheric parameters to search forpossible trends. We
discovered a correlation between the helium abundance and the effective
temperature: the larger the temperature, the larger the photospheric helium
content of sdB stars. Additionally, a separation into two sequences of sdB
stars in the effective temperature - helium abundance plane is detected. We
compared our analysis results with data from the literature. The stars from our
sample are found to be somewhat more luminous. This can only partlybe explained
by NLTE effects. Three apparently normal B stars were discovered, which could
be massive stars far away from the galactic plane (7-19kpc). Radial velocities
were measured for 23 stars from which we discovered a new radial velocity
variable sdB star.


title: The Historical Supernovae

abstract:
  The available historical records of supernovae occurring in our own Galaxy
over the past two thousand years are reviewed. These accounts include the
well-recorded supernovae of AD 1604 (Kepler's SN), 1572 (Tycho's SN), 1181,
1054 (which produced the Crab Nebula) and 1006, together with less certain
events dating back to AD 185. In the case of the supernovae of AD 1604 and 1572
it is European records that provide the most accurate information available,
whereas for earlier supernovae records are principally from East Asian sources.
Also discussed briefly are several spurious supernova candidates, and the
future prospects for studies of historical supernovae.


title:
Simultaneous time-series spectroscopy and multi-band photometry of the
  sdBV PG 1605+072

abstract:
  We present time-series spectroscopy and multi-band photometry of the sdBV PG
1605+072 carried out simultaneously at the Calar Alto 2.2m and 3.5m telescopes.
The periodogram analysis of the radial velocity curves reveals three
frequencies at 2.078, 2.756, and 1.985 mHz for Hbeta and at 2.076, 2.753, and
1.978 mHz for Hgamma. The corresponding radial velocity amplitudes are 12.7,
8.0, and 7.9 km/s for Hbeta and 14.3, 6.5, and 7.2 km/s for Hgamma.
Furthermore, we found five frequencies that are present in all wavelength bands
of the BUSCA photometer. The frequencies detected in the radial velocity curves
are recovered by the photometric measurements. Moreover, additional frequencies
were present in the periodograms which could not be identified in all four
bands simultaneously. The comparison of the amplitudes presented here with
previous results from radial velocity and photometric observations of PG
1605+072 shows a significant change or even switch in the power of the modes
within short time scales, i. e. about one year. No changes in frequency were
registered and the phases of the modes show no wavelength dependency within our
multi-band photometry.


title:
Coarse Estimation of Physical Parameters of Eclipsing Binaries by Means
  of Automative Scripting

abstract:
  Because of GAIA's estimated harvest of cca. 10^5 eclipsing binaries (Munari
et al. 2001) automative procedures for extracting physical parameters from
observations must be introduced. We present preliminary results of automative
scripting applied to 5 eclipsing binaries, for which photometric and radial
velocity observations were taken from literature. Although the results are
encouraging, extensive testing on a wider sample has to be performed.


title:
Polarization of cosmic microwave background scattered by moving flat
  protoobjects

abstract:
  The work is devoted to the investigations of possible observational
manifestations of protoobjects related to "dark ages" epoch (10 < z < 1000),
before formation of self-luminous galaxies and stars. These objects can distort
the cosmic microwave background. Formation of these objects is described in the
"pancake theory" and in the model of "hierarchic clustering". According to
these theories we may consider these protoobjects as flat layers. We consider
both Thomson (with Rayleigh phase matrix) and resonance (for complete frequency
redistribution) scattering of cosmic microwave background radiation by moving
flat layer. The appearing anisotropy and polarization of cosmic microwave
radiation are calculated for a wide range of a layer optical thicknesses (from
optically thin layer to optically thick one). Analytical solutions are also
obtained for the case of an optically thin layer and are compared with the
numerical ones.


title: Gravitational waves from gamma-ray bursts

abstract:
  We present a mechanism for long bursts of gravitational radiation from Kerr
black holes surrounded by a torus. These systems are believed to form in
core-collapse of massive stars in association with gamma-ray bursts. The torus
catalyzes black hole-spin energy mostly into gravitational radiation, with a
minor output in winds, thermal and neutrino emissions. Torus winds impact the
remnant envelope of the progenitor star from within, which may account for
X-ray emission lines and leaves a supernova remnant. The frequency in
gravitational radiation satisfies f_{gw}=470Hz (E_{SNR}/4\times
10^{51})^{1/2}(0.1/\beta)^{1/2}(7M_\odot/M_H)^{3/2}, where E_{SNR} is the
kinetic energy in the SNR, M_H is the black hole mass and \beta\simeq0.1 the
initial ejection velocity, as detected in GRB 011211. Ultimately, this leaves a
black hole binary surrounded by a SNR, which is conceivably illustrated by RX
J050736-6847.8.


title: Polarization of Gamma--Ray Burst Optical and Near-Infrared Afterglows

abstract:
  Gamma-Ray Burst afterglow polarization measurements, in spite of their
intrinsic difficulties, have been carried out for a number of events that
begins to be adequate to draw some general statistical conclusions. Although
the presence of some degree of intrinsic polarization seems to be well
established, there are still open problems regarding the polarization time
evolution and the possible contribution of polarization induced by dust in the
host galaxies.


title: The XMM-Newton-MSSL survey of Polars

abstract:
  The XMM-Newton-MSSL survey of polars is a snapshot survey of nearly 40
polars. We present the initial results, with an emphasis on the energy balance
in these systems and the number of systems which were observed in a low
accretion state. In contrast to the ROSAT results, we find that the vast
majority of polars show no `soft X-ray excess'. We find that half of our sample
were observed in low or off accretion states. We find no evidence that these
systems were biased towards certain orbital periods.


title: XMM-Newton Surveys of the CFRS Fields - I: The Sub-mm/X-ray relation

abstract:
  First results from XMM-Newton observations of the Canada France Redshift
Survey (CFRS) 3hr, 10hr and 14hr fields are presented. Limited regions of two
of the XMM surveys (3 and 14hr) are compared to the Canada UK Deep sub-mm
Surveys (CUDSS) undertaken with SCUBA. None of the 27 SCUBA sources in the 3hr
field are detected by XMM, while one of the 23 SCUBA sources in the 14hr field
is found to coincide with an X-ray source. The SCUBA population as a whole is
not significantly detected in either the 0.5-2 keV or the 2-10 keV X-ray bands,
even after coadding the X-ray flux at the SCUBA positions, in both fields. The
18 X-ray sources within the CUDSS 3hr map yield a mean sub-mm flux of
0.48+-0.27 mJy after coadding the sub-mm flux at the X-ray positions. Using
this result we place an upper limit on the contribution of AGN to the sub-mm
background at 850 microns of ~7 per cent. Conversely we estimate the
contribution of sub-mm sources to the 0.5-2 keV X-ray background to be <16.5
per cent. These results strongly support the conclusion that the two
backgrounds are caused by different processes, in the one case nucleosynthesis
in stars, in the other accretion onto black-holes. We conclude that it is
possible for SCUBA sources in general to contain AGN, as long as they are
Compton-thick and are at z>2.3. The ratio of the X-ray to sub-mm flux for the
X-ray sources however, implies that even when a galaxy does contain an AGN,
most of the energy heating the dust is from young stars and not from the active
nucleus.


title: Fast object detection for use onboard satellites

abstract:
  We propose an object detection algorithm which is efficient and fast enough
to be used in (almost) real time with the limited computer capacities onboard
satellites.
  For stars below the saturation limit of the CCD detectors it is based on a
four neighbourhood local maximum criterion in order to find the centre of a
stellar image. For saturated stars it is based on the assumption that the image
is increasing monotonically towards the centre in the unsaturated part of the
image. The algorithm also calculates approximate stellar magnitudes and
efficiently rejects most of the cosmics which would otherwise lead to a large
number of false detections. The quality of the algorithm was evaluated with the
help of a large set of simulated data for the DIVA satellite mission; different
assumptions were made for the noise level, and the presence of cosmics or for a
variable sky background. We could show that our algorithm fulfills the
requirements for DIVA; only in the case of simulated images which included the
bright galaxy M31 some fainter stars could not be detected in the galaxy's
vicinity. Since stellar images contain large areas without any stars, we
propose an additional block-skipping algorithm which can be coded on
special-purpose hardware.


title:
The Evolution of Substructure in Galaxy, Group and Cluster Haloes I:
  Basic Dynamics

abstract:
  The hierarchical mergers that form the haloes of dark matter surrounding
galaxies, groups and clusters are not entirely efficient, leaving substantial
amounts of dense substructure, in the form of stripped halo cores or
`subhaloes', orbiting within these systems. Using a semi-analytic model of
satellite dynamics, we study the evolution of haloes as they merge
hierarchically, to determine how much substructure survives merging and how the
properties of individual subhaloes change over time. We find that subhaloes
evolve, due to mass loss, orbital decay, and tidal disruption, on a
characteristic time-scale equal to the period of radial oscillations at the
virial radius of the system. Subhaloes with realistic densities and density
profiles lose 25-45 per cent of their mass per pericentric passage, depending
on their concentration and on the circularity of their orbit. As the halo
grows, the subhalo orbits also grow in size and become less bound. Based on
these general patterns, we suggest a method for including realistic amounts of
substructure in semi-analytic models based on merger trees. We show that the
parameters in the resulting model can be fixed by requiring self-consistency
between different levels of the merger hierarchy. In a companion paper, we will
compare the results of our model with numerical simulations of halo formation.


title:
Abundance Anomalies in the X-ray Spectra of the Planetary Nebulae NGC
  7027 and BD +30 363

abstract:
  We revisit Chandra observations of the planetary nebulae NGC 7027 and BD +30
3639 in order to address the question of abundance anomalies in the X-ray
emitting gas. Enhanced abundances relative to solar of magnesium (Mg) for NGC
7027 and neon (Ne) for BD +30 3639 are required to fit their X-ray spectra,
whereas observations at optical and infrared wavelengths show depleted Mg and
Ne in these systems. We attribute the enhancement of Mg in NGC 7027 in the
X-ray, relative to the optical, to the depletion of Mg onto dust grains within
the optical nebula. For BD +30 3639, we speculate that the highly enhanced Ne
comes from a WD companion, which accreted a fraction of the wind blown by the
asymptotic giant branch progenitor, and went through a nova-like outburst which
enriched the X-ray emitting gas with Ne.


title: Collisionless evaporation from cluster elliptical galaxies

abstract:
  We describe a particular aspect of the effects of the parent cluster tidal
field (CTF) on stellar orbits inside cluster Elliptical galaxies. In particular
we discuss, with the aid of a simple numerical model, the possibility that
collisionless stellar evaporation from elliptical galaxies is an effective
mechanism for the production of the recently discovered intracluster stellar
populations. A preliminary investigation, based on very idealized galaxy
density profiles (Ferrers density distributions), showed that over an Hubble
time, the amount of stars lost by a representative galaxy may sum up to the 10%
of the initial galaxy mass, a fraction in interesting agreement with
observational data. The effectiveness of this mechanism is due to the fact that
the galaxy oscillation periods near equilibrium configurations in the CTF are
comparable to stellar orbital times in the external galaxy regions. Here we
extend our previous study to more realistic galaxy density profiles, in
particular by adopting a triaxial Hernquist model.


title: Cosmology and Life

abstract:
  I examine some recent findings in cosmology and their potential implications
for the emergence of life in the universe. In particular, I discuss the
requirements for carbon-based life, anthropic considerations with respect to
the nature of dark energy, the possibility of time-varying constants of nature,
and the question of the rarity of intelligent life.


title: A First Estimate of the Baryonic Mass Function of Galaxies

abstract:
  We estimate the baryonic (stellar+cold gas) mass function of galaxies in the
local Universe by assigning a complete sample of Two Micron All Sky Survey and
Sloan Digital Sky Survey galaxies a gas fraction based on a statistical sample
of the entire population, under the assumption of a universally-applicable
stellar initial mass function. The baryonic mass function is similar to the
stellar mass function at the high mass end, and has a reasonably steep
faint-end slope owing to the typically high cold gas fractions and low stellar
mass-to-light ratios characteristic of low-mass galaxies. The Schechter
Function fit parameters are phi* = 0.0108(6) per cubic Mpc per dex of mass, M*
= 5.3(3)x10^10 solar masses, and alpha = -1.21(5), with formal error estimates
given in parentheses (for a Hubble constant of 100 km/s per Mpc). We show that
the neutral and molecular hydrogen mass functions derived using this indirect
route are in agreement with direct estimates, validating our indirect method.
Integrating under the baryonic mass function and incorporating all sources of
uncertainty, we find that the baryonic (stellar+cold gas) mass density implied
by this estimate is Omega_cold baryon = 0.0024+0.0007-0.0014, or 8% +4% -5% of
the Big Bang nucleosynthesis expectation.


title: New X-ray quasars behind the Small Magellanic Cloud

abstract:
  We present five X-ray quasars behind the Small Magellanic Cloud, increasing
the number of known quasars behind the SMC by ca. 40%. They were identified via
follow-up spectroscopy of serendipitous sources from the Chandra X-ray
Observatory matched with objects from the OGLE database. All quasars lie behind
dense parts of the SMC, and could be very useful for proper motion studies. We
analyze X-ray spectral and timing properties of the quasars. We discuss
applications of those and other recently discovered quasars behind the SMC to
the studies of absorption properties of the Cloud, its proper motion, and for
establishing the geometrical distance to the SMC.


title:
Maximal mass of uniformly rotating homogeneous stars in Einsteinian
  gravity

abstract:
  Using a multi domain spectral method, we investigate systematically the
general-relativistic model for axisymmetric uniformly rotating, homogeneous
fluid bodies generalizing the analytically known Maclaurin and Schwarzschild
solutions. Apart from the curves associated with these solutions and a further
curve of configurations that rotate at the mass shedding limit, two more curves
are found to border the corresponding two parameter set of solutions. One of
them is a Newtonian lens shaped sequence bifurcating from the Maclaurin
spheroid sequence, while the other one corresponds to highly relativistic
bodies with an infinite central pressure. The properties of the configuration
for which both the gravitational and the baryonic masses, moreover angular
velocity, angular momentum as well as polar red shift obtain their maximal
values are discussed in detail. In particular, by comparison with the static
Schwarzschild solution, we obtain an increase of 34.25% in the gravitational
mass. Moreover, we provide exemplarily a discussion of angular velocity and
gravitational mass on the entire solution class.


title:
On the Early Evolution of Forming Jovian Planets I: Initial Conditions,
  Systematics and Qualitative Comparisons to Theory

abstract:
  (abridged) We analyze the formation and migration of a proto-Jovian companion
in a circumstellar disk in 2d, during the period in which the companion makes
its transition from `Type I' to `Type II' migration, using a PPM code. Spiral
waves are generated by the gravitational torque of the planet on the disk.
Their effects are to cause the planet to migrate inward and the disk to form a
deep (low surface density) gap. Until a transition to slower Type II migration,
the migration rate of the planet is of order 1 AU/10$^3$ yr, and varies by less
than a factor of two with a factor twenty change in planet mass, but depends
near linearly on the disk mass. Although the disk is stable to self gravitating
perturbations (Toomre $Q>5$ everywhere), migration is faster by a factor of two
or more when self gravity is suppressed. Migration is equally sensitive to the
disk's mass distribution within 1--2 Hill radii of the planet, as demonstrated
by our simulations' sensitivity to the planet's assumed gravitational softening
parameter. Rapid migration can continue after gap formation. Gaps are typically
several AU in width and display the \mplan$^{2/3}$ proportionality predicted by
theory. Beginning from an initially unperturbed 0.05\msun disk, planets of mass
$M_{\rm pl}> 0.3$\mj can open a gap deep and wide enough to complete the
transition to slower \ttwo migration. Lower mass objects continue to migrate
rapidly, eventually impacting the inner boundary of our grid. This transition
mass is much larger than that predicted as the `Shiva mass' discussed in Ward
and Hahn (2000), making the survival of forming planets even more precarious
than they would predict.


title:
On the Early Evolution of Forming Jovian Planets II: Analysis of
  Accretion and Gravitational Torques

abstract:
  (abridged) We find that a disk can supply a forming planet with mass at an
essentially infinite rate ($\sim1$\mj/25 yr) so that a gap could form very
quickly. We show that mass accretion rates faster than $\sim10^{-4}$\mj/yr are
not physically reasonable in the limit of either a thin, circumplanetary disk
or of a spherical envelope. Planet growth and ultimately survival are therefore
limited to the planet's ability to accept additional matter, not by the disk in
which it resides. We find that common analytic torque approximations predict
values that are a factor $\sim10$ larger than those obtained from the
simulations. Accounting for the disk's vertical structure (crudely modeled
through a gravitational softening parameter), small shifts in resonance
positions due to pressure gradients, to disk self gravity and to inclusion of
non-WKB terms in the analysis (Artymowicz 1993) reduce the difference to a
factor $\sim3-6$. Torques from the corotation resonances that are positive in
sign contribute 20-30% or more of the net torque on the planet. The assumption
of linearity underlying theoretical analyses is recovered in the simulations
with planets with masses below 0.5\mj, but the assumption that interactions
occur only at the resonances is more difficult to support. The detailed shape
of the disk's response varies from pattern to pattern, making its true position
less clear. We speculate that the finite width allows for overlap and mixing
between resonances and may be responsible for the remainder of the differences
between torques from theory and simulation, but whether accounting for such
overlap in a theory will improve the agreement with the simulations is not
clear.


title:
Blue Supergiants as a Tool for Extragalactic Distances - Theoretical
  Concepts

abstract:
  Because of their enormous intrinsic brightness blue supergiants are ideal
stellar objects to be studied spectroscopically as individuals in galaxies far
beyond the Local Group. Quantitative spectroscopy by means of efficient
multi-object spectrographs attached to 8m-class telescopes and modern NLTE
model atmosphere techniques allow us to determine not only intrinsic stellar
parameters such as effective temperature, surface gravity, chemical composition
and absolute magnitude but also very accurately interstellar reddening and
extinction. This is a significant advantage compared to classical distance
indicators like Cepheids and RR Lyrae. We describe the spectroscopic
diagnostics of blue supergiants and introduce two concepts to determine
absolute magnitudes. The first one (Wind Momentum -- Luminosity Relationship)
uses the correlation between observed stellar wind momentum and luminosity,
whereas the second one (Flux-weighted Gravity -- Luminosity Relationship)
relies only on the determination of effective temperature and surface gravity
to yield an accurate estimate of absolute magnitude. We discuss the potential
of these two methods.


title: No X-ray Bright Type II Quasars Among the Lyman-alpha Emitters

abstract:
  The Lyman-alpha emitters found at z=4.5 and 5.7 by the Large Area Lyman Alpha
(LALA) survey have high equivalent widths in the Lyman-alpha line. Such lines
can be produced by narrow-lined active galactic nuclei (AGNs) or by stellar
populations with a very high proportion of young, massive stars. To check for
Type-II (i.e., narrow-lined) quasars, we obtained a deep X-ray image of 49
Lyman-alpha sources in a single field of the ACIS instrument on the Chandra
X-ray Observatory. None of these sources were detected with a 3-sigma limiting
X-ray luminosity of 2.9x10^{43} ergs/s. For comparison, the two known high
redshift type-II quasars have luminosities of 4x10^{43} ergs/s before
extinction correction. The sources remain undetected in stacked images of the
49 lyman-alpha sources (with 6.5 Mega-seconds effective Chandra on-axis
exposure) at 3-sigma limits of 4.9x10^{42} ergs/s. The resulting X-ray to
lyman-alpha ratio is about 4-24 times lower than the ratio for known type-II
quasars, while the average Lyman-alpha luminosity of the LALA sample is in
between the two type-II's. The cumulative X-ray to Lyman-alpha ratio limit is
also below that of 90% of low-redshift Seyfert galaxies.


title: Large-Scale Structure and Future Surveys

abstract:
  As the 2dF Galaxy Redshift Survey and Sloan Digital Sky Survey move toward
completion, it is time to ask what the next generation of survey of large-scale
structure should be. I discuss some of the cosmological justifications for such
surveys and conclude that surveys at z=3 offer a critical advantage in their
ability to access linear-regime clustering at scales smaller than any current
survey and even the CMB. I discuss a possible implementation of such a survey
and highlight some of the potential science return.


title: Early-type galaxies in the SDSS. II. Correlations between observables

abstract:
  A magnitude limited sample of nearly 9000 early-type galaxies, in the
redshift range 0.01 < z < 0.3, was selected from the Sloan Digital Sky Survey
using morphological and spectral criteria. The sample was used to study how
early-type galaxy observables, including luminosity L, effective radius R_o,
surface brightness I_o, color, and velocity dispersion sigma, are correlated
with one another. Measurement biases are understood with mock catalogs which
reproduce all of the observed scaling relations and their dependences on
fitting technique. At any given redshift, the intrinsic distribution of
luminosities, sizes and velocity dispersions in our sample are all
approximately Gaussian. A maximum likelihood analysis shows that sigma ~
L^{0.25\pm 0.012}, R_o ~ L^{0.63\pm 0.025}, and R_o ~ I^{-0.75\pm 0.02} in the
r* band. In addition, the mass-to-light ratio within the effective radius
scales as M_o/L ~ L^{0.14\pm 0.02} or M_o/L ~ M_o^{0.22\pm 0.05}, and galaxies
with larger effective masses have smaller effective densities: Delta_o ~
M_o^{-0.52\pm 0.03}. These relations are approximately the same in the g*, i*
and z* bands. Relative to the population at the median redshift in the sample,
galaxies at lower and higher redshifts have evolved only little, with more
evolution in the bluer bands. The luminosity function is consistent with weak
passive luminosity evolution and a formation time of about 9 Gyrs ago.


title: The Effect of Cosmic Ray Diffusion on the Parker Instability

abstract:
  The Parker instability, which has been considered as a process governing the
structure of the interstellar medium, is induced by the buoyancy of magnetic
field and cosmic rays. In previous studies, while the magnetic field has been
fully incorporated in the context of isothermal magnetohydrodynamics, cosmic
rays have been normally treated with the simplifying assumption of infinite
diffusion along magnetic field lines but no diffusion across them. The cosmic
ray diffusion is, however, finite. In this work, we take into account fully the
diffusion process of cosmic rays in a linear stability analysis of the Parker
instability. Cosmic rays are described with the diffusion-convection equation.
With realistic values of cosmic ray diffusion coefficients expected in the
interstellar medium, we show that the result of previous studies with the
simplifying assumption on cosmic ray diffusion applies well. Finiteness of
parallel diffusion decreases the growth rate of the Parker instability, while
the relatively smaller perpendicular diffusion has no significant effect. We
discuss the implication of our result on the role of the Parker instability in
the interstellar medium.


title: Early-type galaxies in the SDSS. III. The Fundamental Plane

abstract:
  A magnitude limited sample of nearly 9000 early-type galaxies, in the
redshift range 0.01 < z < 0.3, was selected from the Sloan Digital Sky Survey
using morphological and spectral criteria. The Fundamental Plane relation in
this sample is R_o ~ sigma^{1.49\pm 0.05} I_o^{-0.75\pm 0.01} in the r* band.
It is approximately the same in the g*, i* and z* bands. Relative to the
population at the median redshift in the sample, galaxies at lower and higher
redshifts have evolved only little. If the Fundamental Plane is used to
quantify this evolution then the apparent magnitude limit can masquerade as
evolution; once this selection effect has been accounted for, the evolution is
consistent with that of a passively evolving population which formed the bulk
of its stars about 9 Gyrs ago. One of the principal advangtages of the SDSS
sample over previous samples is that the galaxies in it lie in environments
ranging from isolation in the field to the dense cores of clusters. The
Fundamental Plane shows that galaxies in dense regions are slightly different
from galaxies in less dense regions.


title: The Jet Angular Profile and the Afterglow Light Curves

abstract:
  We investigate how the angular structure of GRB jets effects the afterglow
light curves at different viewing angles, $\theta_{v}$, from the jet symmetry
axis. A numerical hydrodynamical modeling for the evolution of a relativistic
collimated outflow, as it interacts with the surrounding medium, is carried
out, and compared to two simple models that make opposite and extreme
assumptions for the degree of lateral energy transfer. The Lorentz factor,
$\Gamma$, and kinetic energy per unit solid angle, $\epsilon$, are initially
taken to be power laws of the angle $\theta$ from the jet axis. We find that
the lateral velocity in the comoving frame, $v'_\theta$, is typically much
smaller than the sound speed, $c_s$, as long as $\Gamma\gg 1$, and the dynamics
of relativistic structured jets may be reasonably described by a simple
analytic model where $\epsilon$ is independent of time, as long as
$\Gamma(\theta=0)\ga$ a few. We perform a qualitative comparison between the
resulting light curves and afterglow observations. This constrains the jet
structure, and poses problems for a `universal' jet model, where all GRB jets
are assumed to be intrinsically identical, and differ only by our viewing
angle, $\theta_{v}$.


title:
The Detectability of the First Stars and Their Cluster Enrichment
  Signatures

abstract:
  We conduct a comprehensive investigation of the detectability of the first
stars and their enrichment signatures in galaxy clusters. We show that the mean
metallicity of outflows from objects containing these Population III (PopIII)
stars is well above the critical transition metallicity (Z_cr \sim 10^-4) that
marks the formation of normal stars. Thus the fraction of PopIII objects formed
as a function of redshift is heavily dependent on the distribution of metals
and fairly independent of the precise value of Z_cr. Using an analytical model
of inhomogenous structure formation, we study the evolution of PopIII objects
as a function of the star formation efficiency, IMF, and efficiency of outflow
generation. For all models, PopIII objects tend to be in the 10^6.5-10^7.0
solar mass range, just large enough to cool within a Hubble time, but small
enough that they are not clustered near areas of previous star formation.
Although the mean metallicity exceeds Z_cr at a redshift of 15 in all models,
the peak of PopIII star formation occurs at z \sim 10, and such stars continue
to form well into the observable range. We discuss the observational properties
of these objects, some of which may have already been detected in ongoing
surveys of high-redshift Lyman-alpha emitters. Finally, we combine our PopIII
distributions with the yield models of Heger and Woosley (2002) to study their
impact on the intracluster medium (ICM) in galaxy clusters. We find that PopIII
stars can contribute no more than 20% of the iron observed in the ICM, although
their peculiar elemental yields help to reconcile theoretical models with the
observed Fe and Si/Fe abundances. However, these stars tend to overproduce S/Fe
and their associated SN heating falls far short of the observed level of 1 keV
per ICM gas particle.


title: Early-type galaxies in the SDSS. IV. Colors and chemical evolution

abstract:
  The colors and chemical abundances of early-type galaxies at redshifts z<0.3
are studied using a sample of nearly 9000 galaxies, selected from the Sloan
Digital Sky Survey using morphological and spectral criteria. In this sample,
redder galaxies have larger velocity dispersions. Color also correlates with
magnitude and size, but these correlations are entirely due to the L-sigma and
R_o-sigma relations: the primary correlation is color-sigma. The red light in
early-type galaxies is, on average, slightly more centrally concentrated than
the blue. Because of these color gradients, the strength of the
color--magnitude relation depends on whether or not the colors are defined
using a fixed metric aperture. Chemical evolution and star formation histories
of early-type galaxies are investigated using co-added spectra of similar
objects. At fixed sigma, the population at z ~ 0.2 had weaker Mg_2 and stronger
H_beta absorption compared to the population at z ~ 0. It was also bluer.
Comparison of these colors and line-strengths, and their evolution, with
single-burst stellar population models suggests a formation time of 9 Gyrs ago,
consistent with a Fundamental Plane analysis of this sample.


title: Near-Infrared Spectroscopy and Young Stellar Populations

abstract:
  Over the past decade, tremendous progress has been made in applying the
techniques of MK classification to spectra obtained from 1-5 microns. This
spectral region is rich in atomic and molecular features which are temperature
and luminosity sensitive providing a powerful technique to study intrinsically
red and/or heavily dust embedded stellar populations. We will summarize recent
work with particular emphasis on data obtained for a set of 88 fundamental MK
standards in the J-, H-, K-, and L-bands with the KPNO 4m FTS. One area that
has benefited enormously from these efforts has been the study of extremely
young stellar populations still embedded in the molecular cloud cores from
which they formed. Such objects present peculiar challenges in applying the MK
process such as sub-giant surface gravities at late-types and enhanced stellar
activity associated with accretion from circumstellar disks. We will provide an
overview of these difficulties and present preliminary results on possible
solutions.


title: Early-type galaxies in the SDSS. I. The sample

abstract:
  A sample of nearly 9000 early-type galaxies, in the redshift range 0.01 < z <
0.3, was selected from the Sloan Digital Sky Survey using morphological and
spectral criteria. This paper describes how the sample was selected, presents
examples of images and seeing corrected fits to the observed surface brightness
profiles, describes our method for estimating K-corrections, and shows that the
SDSS spectra are of sufficiently high quality to measure velocity dispersions
accurately. It also provides catalogs of the measured photometric and
spectroscopic parameters. In related papers, these data are used to study how
early-type galaxy observables, including luminosity, effective radius, surface
brightness, color, and velocity dispersion, are correlated with one another.


title:
Probing dark energy using baryonic oscillations in the galaxy power
  spectrum as a cosmological ruler

abstract:
  We show that the baryonic oscillations expected in the galaxy power spectrum
may be used as a "standard cosmological ruler'' to facilitate accurate
measurement of the cosmological equation of state. Our approach involves a
straight-forward measurement of the oscillation "wavelength'' in Fourier space,
which is fixed by fundamental linear physics in the early Universe and hence is
highly model-independent. We quantify the ability of future large-scale galaxy
redshift surveys with mean redshifts z~1 and z~3 to delineate the baryonic
peaks in the power spectrum, and derive corresponding constraints on the
parameter w describing the equation of state of the dark energy. For example, a
survey of three times the Sloan volume at z ~ 1 can produce a measurement with
accuracy dw ~ 0.1. We suggest that this method of measuring the dark energy
powerfully complements other probes such as Type Ia supernovae, and suffers
from a different (and arguably less serious) set of systematic uncertainties.


title: The Fe XXII I(11.92 A)/I(11.77 A) Density Diagnostic

abstract:
  Using the Livermore X-ray Spectral Synthesizer, which calculates spectral
models of highly charged ions based on HULLAC atomic data, we investigate the
temperature, density, and photoexcitation dependence of the I(11.92 A)/I(11.77
A) line ratio of Fe XXII. Applied to the Chandra HETG spectrum of the
intermediate polar EX Hya, we find that the electron density of its T_e ~ 12 MK
plasma is log n_e (cm^-3) = 14.3^{+0.7}_{-0.5}, orders of magnitude greater
than that observed in the Sun or other late-type stars.


title:
A Radio Flare from GRB 020405: Evidence for a Uniform Medium Around a
  Massive Stellar Progenitor

abstract:
  We present radio observations of GRB 020405 starting 1.2 days after the
burst, which reveal a rapidly-fading ``radio flare''. Based on its temporal and
spectral properties, we interpret the radio flare as emission from the reverse
shock. This scenario rules out a circumburst medium with a radial density
profile \rho ~ r^{-2} expected around a mass-losing massive star, since in that
case the reverse shock emission decays on the timescale of the burst duration
t~100 s. Using published optical and X-ray data, along with the radio data
presented here, we further show that a self-consistent model requires
collimated ejecta with an opening angle of 6 degrees (t_j~0.95 days). As a
consequence of the early jet break, the late-time (t>10 days) emission measured
with the Hubble Space Telescope significantly deviates from an extrapolation of
the early, ground-based data. This, along with an unusually red spectrum, F_\nu
\~ \nu^{-3.9}, strengthens the case for a supernova that exploded at about the
same time as GRB 020405, thus pointing to a massive stellar progenitor for this
burst. This is the first clear association of a massive progenitor with a
uniform medium, indicating that a \rho ~ r^{-2} profile is not a required
signature, and in fact may not be present on the lengthscales probed by the
afterglow in the majority of bursts.


title:
The Discovery of a Very Narrow-Line Star Forming Obat a Redshift of
  5.66ject

abstract:
  We report on the discovery of a very narrow-line star forming object beyond
redshift of 5. Using the prime-focus camera, Suprime-Cam, on the 8.2 m Subaru
telescope together with a narrow-passband filter centered at $\lambda_{\rm c}$
= 8150 \AA with passband of $\Delta\lambda$ = 120 \AA, we have obtained a very
deep image of the field surrounding the quasar SDSSp J104433.04$-$012502.2 at a
redshift of 5.74. Comparing this image with optical broad-band images, we have
found an object with a very strong emission line. Our follow-up optical
spectroscopy has revealed that this source is at a redshift of
$z=5.655\pm0.002$, forming stars at a rate $\sim 13 ~ h_{0.7}^{-2} ~ M_\odot$
yr$^{-1}$. Remarkably, the velocity dispersion of Ly$\alpha$-emitting gas is
only 22 km s$^{-1}$. Since a blue half of the Ly$\alpha$ emission could be
absorbed by neutral hydrogen gas, perhaps in the system, a modest estimate of
the velocity dispersion may be $\gtrsim$ 44 km s$^{-1}$. Together with a linear
size of 7.7 $h_{0.7}^{-1}$ kpc, we estimate a lower limit of the dynamical mass
of this object to be $\sim 2 \times 10^9 M_\odot$. It is thus suggested that
LAE J1044$-$0123 is a star-forming dwarf galaxy (i.e., a subgalactic object or
a building block) beyond redshift 5 although we cannot exclude a possibility
that most Ly$\alpha$ emission is absorbed by the red damping wing of neutral
intergalactic matter.


title:
Could the 55 Cancri Planetary System Really Be in the 3:1 Mean Motion
  Resonance?

abstract:
  We integrate the orbital solutions of the planets orbiting 55 Cnc. In the
simulations, we find that not only three resonant arguments
$\theta_{1}=\lambda_{1}-3\lambda_{2}+2\tilde\omega_{1}$,
$\theta_{2}=\lambda_{1}-3\lambda_{2}+2\tilde\omega_{2}$ and
$\theta_{3}=\lambda_{1}-3\lambda_{2}+(\tilde\omega_{1}+\tilde\omega_{2})$
librate respectively, but the relative apsidal longitudes $\Delta\omega$ also
librates about $250^{\circ}$ for millions of years. The results imply the
existence of the 3:1 resonance and the apsidal resonance for the studied
system. We emphasize that the mean motion resonance and apsidal locking can act
as two important mechanisms of stabilizing the system. In addition, we further
investigate the secular dynamics of this system by comparing the numerical
results with those given by Laplace-Lagrange secular theory.


title: The Wilson--Bappu Effect: a tool to determine stellar distances

abstract:
  Wilson and Bappu (1957) have shown the existence of a remarkable correlation
between the width of the emission in the core of the K line of Ca II and the
absolute visual magnitude of late--type stars. Here we present a new
calibration of the Wilson--Bappu effect based on a sample of 119 nearby stars.
We use, for the first time, width measurements based on high resolution and
high signal to noise ratio CCD spectra and absolute visual magnitudes from the
Hipparcos database. Our primary goal is to investigate the possibility of using
the Wilson--Bappu effect to determine accurate distances to single stars and
groups. The result of our calibration fitting of the Wilson--Bappu relationship
is M_V=33.2-18.0*log W_0, and the determination seems free of systematic
effects. The root mean square error of the fitting is 0.6 magnitudes. This
error is mostly accounted for by measurement errors and intrinsic variability
of W_0, but in addition a possible dependence on the metallicity is found,
which becomes clearly noticeable for metallicities below [Fe/H]=-0.4. This
detection is possible because in our sample [Fe/H] ranges from -1.5 to 0.4. The
Wilson--Bappu effect can be used confidently for all metallicities not lower
than -0.4, including the LMC. While it does not provide accurate distances to
single stars, it is a useful tool to determine accurate distances to clusters
and aggregates, where a sufficient number of stars can be observed. We apply
the Wilson--Bappu effect to published data of the open cluster M67; the
retrieved distance modulus is of 9.65 magnitude, in very good agreement with
the best distance estimations for this cluster, based on main sequence fitting.


title:
A new method of estimating the mass-to-light ratio of the Ursa Minor
  dwarf spheroidal galaxy

abstract:
  Dwarf satellite galaxies undergo strong tidal forces produced by the main
galaxy potential. These forces disturb the satellite, producing asymmetries in
its stellar distribution, tidal tail formation, and modifications of the
velocity dispersions profiles. Most of these features are observed in the Ursa
Minor (UMi) dwarf spheroidal galaxy, which is one of the closest satellites of
the Milky Way. These features show that UMi is been tidally disrupted and
probably not in virial equilibrium. The high velocity dispersion of UMi could
also be a reflection of this tidal disruption and not the signature of the
large dark matter content that would be deduced if virial equilibrium is
assumed. In order to avoid the uncertainty produced when virial equilibrium is
assumed in systems in strong tidal fields, we present a new method of
calculating the mass-to-luminosity ratio of disrupted dwarf galaxies. This
method is based on numerical simulations and only takes into account the shape
of the dwarf density profile and the tidal tail brightness, but does not depend
on the kinematics of the dwarf. Applying this method to UMi, we obtain a
mass-to-luminosity relation of 12, which is lower than the value obtained
assuming virial equilibrium (M/L=60). In addition, if UMi has a large
dark-matter content, it will be impossible to reproduce a tidal tail as
luminous as the one observed.


title:
Magnetic field evolution in galaxies interacting with the intracluster
  medium. 3D numerical simulations

abstract:
  A fully three-dimensional (3D) magnetohydrodynamical (MHD) model is applied
to simulate the evolution of the large-scale magnetic field in cluster galaxies
interacting with the intra-cluster medium (ICM). As the model input we use a
time dependent gas velocity field resulting from 3D N-body sticky-particle
simulations of a galaxy. The modeled clouds are affected by the ram pressure
due to their rapid motion through the ICM in the central part of a cluster.
Numerical simulations have shown that after the initial compression phase due
to ram pressure a process of gas re-accretion onto the galactic disk takes
place. We find that the gas re-accretion leads to an increase of the total
magnetic energy without any dynamo action. The simulated magnetic fields are
used to construct the model maps of high-frequency (Faraday rotation-free)
polarized radio emission. We show that the evolution of the polarized intensity
shows features that are characteristic for different evolutionary stages of an
ICM-ISM interaction. The comparison of polarized radio continuum emission maps
with our model permits to determine whether the galaxy is in the compression or
in the re-accretion phase. It also provides an important constraint upon the
dynamical modeling of an ICM-ISM interactions.


title: Quintessence From a Decaying Dark Matter

abstract:
  It is a known fact that a quintessence model with $w_q < -1$ fits the
publicly available Super Nova (SN) type Ia data better than a model with
cosmological constant or $w_q > -1$. Two types of models have this property:
Scalar fields with unconventional kinetic term and models with cosmological
constant and a slowly decaying Cold Dark Matter (CDM). In this work we
investigate the possibility of replacing the cosmological constant in the
latter models with gradual condensation of a scalar field produced during the
decay of the CDM and present some preliminary results. The advantage of this
class of models to the ordinary quintessence is that the evolution of the dark
energy and CDM are correlated and cosmological coincidence problem is solved or
at least reduced to the fine tuning of the coupling between decaying CDM and
quintessence field i.e the Hierarchy problem. Here we show that for part of the
parameter space these models are consistent with present estimation of
cosmological parameters.


title:
Reconstruction of the primordial Universe by a
  Monge--Ampere--Kantorovich optimisation scheme

abstract:
  A method for the reconstruction of the primordial density fluctuation field
is presented. Various previous approaches to this problem rendered {\it
non-unique} solutions. Here, it is demonstrated that the initial positions of
dark matter fluid elements, under the hypothesis that their displacement is the
gradient of a convex potential, can be reconstructed uniquely. In our approach,
the cosmological reconstruction problem is reformulated as an assignment
problem in optimisation theory. When tested against numerical simulations, our
scheme yields excellent reconstruction on scales larger than a few megaparsecs.


title: Emission line studies of young radio sources

abstract:
  We demonstrate the efficiency of high quality optical spectroscopic
observations of two compact radio sources, PKS 1549-79 and PKS 1345+12, as a
probe of the kinematics and physical conditions in the circumnuclear gas in the
early stages of radio source evolution. We outline a schematic model for PKS
1345+12 based on the model for PKS 1549-79 proposed by Tadhunter et al. (2001)
in which the young radio source is expanding through a dense and dusty
enshrouding cocoon, sweeping material out of the circumnuclear regions.


title:
A stochastic Monte Carlo approach to model real star cluster evolution,
  III. Direct integrations of three- and four-body interactions

abstract:
  Spherically symmetric equal mass star clusters containing a large amount of
primordial binaries are studied using a hybrid method, consisting of a gas
dynamical model for single stars and a Monte Carlo treatment for relaxation of
binaries and the setup of close resonant and fly-by encounters of single stars
with binaries and binaries with each other (three- and four-body encounters).
What differs from our previous work is that each encounter is being integrated
using a highly accurate direct few-body integrator which uses regularized
variables. Hence we can study the systematic evolution of individual binary
orbital parameters (eccentricity, semi-major axis) and differential and total
cross sections for hardening, dissolution or merging of binaries (minimum
distance) from a sampling of several ten thousands of scattering events as they
occur in real cluster evolution including mass segregation of binaries,
gravothermal collapse and reexpansion, binary burning phase and ultimately
gravothermal oscillations. For the first time we are able to present empirical
cross sections for eccentricity variation of binaries in close three- and
four-body encounters. It is found that a large fraction of three-body and
four-body encounters results in merging. Previous cross sections obtained by
Spitzer and Gao for strong encounters can be reproduced, while for weak
encounters non-standard processes like formation of hierarchical triples occur.


title: Two more years of GRB optical afterglows

abstract:
  I review the main observational achievements concerning GRB optical
afterglows occurred in the past two years. Their emission seems to be well
interpreted in terms of the `fireball' model, although a variety of behaviours
are observed. Evidence for supernova-like late time `bumps' in the optical
light curves is growing; however, other interpretations are possible. Fast
follow-up observations allowed the detection of faint optical afterglows, and
seem to suggest that a fraction of the so-called `dark' bursts might actually
be re-classified as `dim' GRBs. Perspectives for future observations in this
field are also outlined.


title: Simulations of Early Structure Formation: Primordial Gas Clouds

abstract:
  (abridged) We use large cosmological simulations to study the origin of
primordial star-forming clouds in a Lambda CDM universe, by following the
formation of dark matter halos and the cooling of gas within them. To model the
physics of chemically pristine gas, we employ a non-equilibrium treatment of
the chemistry of 9 species and include cooling by molecular hydrogen. We
explore the hierarchical growth of bound structures forming at redshifts z = 25
- 30 with total masses in the range 10^5 - 10^6 Msun. The complex interplay
between the gravitational formation of dark halos and the thermodynamic and
chemical evolution of the gas clouds compromises analytic estimates of the
critical H2 fraction. Dynamical heating from mass accretion and mergers opposes
relatively inefficient cooling by molecular hydrogen, delaying the production
of star-forming clouds in rapidly growing halos. We also investigate the impact
of photo-dissociating ultra-violet (UV) radiation on the formation of
primordial gas clouds. We consider two extreme cases by first including a
uniform radiation field in the optically thin limit and secondly by accounting
for the maximum effect of gas self-shielding in virialized regions. In both the
cases we consider, the overall impact can be described by computing an
equilibrium H2 abundance for the radiation flux and defining an effective
shielding factor.
  Based on our numerical results, we develop a semi-analytic model of the
formation of the first stars, and demonstrate how it can be coupled with large
N-body simulations to predict the star formation rate in the early universe.


title: The Chandra Observation of the IP TX Col

abstract:
  We present a preliminary look at the serendipitous observation of the
intermediate polar TX Col by Chandra. The 52 ksec observation is uninterrupted,
providing an opportunity to disentangle the light curve and power spectra
components. We illustrate the energy-dependence of the power spectrum.


title: Spheroid and disk signatures in galaxy bulges

abstract:
  Recent progress on the structure and dynamics of bulges is reviewed. Those
aspects that link galaxy bulges either to oblate spheroids akin to elliptical
galaxies or to rapidly-rotating, flattened systems more nearly resembling the
products of disk internal transformations, are highlighted. The analysis of
surface brightness profiles derived from HST data is reviewed to show that
unresolved nuclear components detected by HST have biased the determination of
surface brightness profiles obtained from the ground; r^1/4 profiles are
virtually nonexistent in galaxy bulges. Predictions from accretion N-body
models on the shape of surface brightness profiles are discussed. The position
of bulges on the Fundamental Plane of elliptical galaxies is examined to infer
clues on bulge population ages and bulge dynamical structure. Kinematic
diagnostics on the internal dynamics of bulges are examined. Finally, a new
approach to the kinematic analysis of galaxies, based on the use of synthetic
spectra of single stellar population models instead of the standard stellar
templates, is presented.


title:
Model atmosphere analysis of the extreme DQ white dwarf GSC2U
  J131147.2+292348

abstract:
  A new model atmosphere analysis for the peculiar DQ white dwarf discovered by
Carollo et al. (2002) is presented. The effective temperature and carbon
abundance have been estimated by fitting both the photometric data
(UBJ,VRF,IN,JHK) and a low resolution spectrum (3500<lambda<7500 A) with a new
model grid for helium-rich white dwarfs with traces of carbon (DQ stars). We
estimate Teff ~ 5120 +/- 200 K and log[C/He] ~ -5.8 +/- 0.5, which make GSC2U
J131147.2+292348 the coolest DQ star ever observed. This result indicates that
the hypothetical transition from C2 to C2H molecules around Teff = 6000 K,
which was inferred to explain the absence of DQ stars at lower temperatures,
needs to be reconsidered.


title: Ultraviolet spectroscopy of narrow coronal mass ejections

abstract:
  We present Ultraviolet Coronagraph Spectrometer (UVCS) observations of 5
narrow coronal mass ejections (CMEs) that were among 15 narrow CMEs originally
selected by Gilbert et al. (2001). Two events (1999 March 27, April 15) were
"structured", i.e. in white light data they exhibited well defined interior
features, and three (1999 May 9, May 21, June 3) were "unstructured", i.e.
appeared featureless. In UVCS data the events were seen as 4-13 deg wide
enhancements of the strongest coronal lines HI Ly-alpha and OVI (1032,1037 A).
We derived electron densities for several of the events from the Large Angle
Spectrometric Coronagraph (LASCO) C2 white light observations. They are
comparable to or smaller than densities inferred for other CMEs. We modeled the
observable properties of examples of the structured (1999 April 15) and
unstructured (1999 May 9) narrow CMEs at different heights in the corona
between 1.5 and 2 R(Sun). The derived electron temperatures, densities and
outflow speeds are similar for those two types of ejections. They were compared
with properties of polar coronal jets and other CMEs. We discuss different
scenarios of narrow CME formation either as a jet formed by reconnection onto
open field lines or CME ejected by expansion of closed field structures.
Overall, we conclude that the existing observations do not definitively place
the narrow CMEs into the jet or the CME picture, but the acceleration of the
1999 April 15 event resembles acceleration seen in many CMEs, rather than
constant speeds or deceleration observed in jets.


title: ULXs, Microblazars, and the Unidentified EGRET sources

abstract:
  We suggest that ultraluminous X-ray sources (ULXs) and some of the variable
low latitude EGRET gamma-ray sources may be two different manifestations of the
same underlying phenomena: high-mass microquasars with relativistic jets
forming a small angle with the line of sight (i.e. microblazars). Microblazars
with jets formed by relatively cool plasma (Lorentz factors for the leptons up
to a few hundreds) naturally lead to ULXs. If the jet contains very energetic
particles (high-energy cutoff above Lorentz factors of several thousands) the
result is a relatively strong gamma-ray source. As pointed out by Kaufman
Bernado, Romero & Mirabel (2002), a gamma-ray microblazar will always have an
X-ray counterpart (although it might be relatively weak), whereas X-ray
microblazars might have no gamma-ray counterparts.


title: CO Depletion and Deuterium Fractionation in Prestellar Cores

abstract:
  We report the detection of D2CO in a sample of starless dense cores, in which
we previously measured the degree of CO depletion. The deuterium fractionation
is found extremely high, [D2CO]/[H2CO] ~ 1-10 %, similar to that reported in
low-mass protostars. This provides convincing evidence that D2CO is formed in
the cold pre-stellar cores, and later desorbed when the gas warms up in
protostars. We find that the cores with the highest CO depletions have also the
largest [D2CO]/[H2CO] ratios, supporting the theoretical prediction that
deuteration increases with increasing CO depletion.


title:
Models of the Morphology, Kinematics, and Star Formation History of the
  Prototypical Collisional Starburst System: NGC 7714/7715 = Arp 284

abstract:
  (abridged) We present new N-body, hydrodynamical simulations of the
interaction between the starburst galaxy NGC 7714 and its post-starburst
companion NGC 7715, focusing on the formation of the collisional features,
including: 1) the gas-rich star forming bridge, 2) the large gaseous loop (and
stellar tails) to the west of the system, 3) the very extended HI tail to the
west and north of NGC 7714, and 4) the partial stellar ring in NGC 7714. Our
simulations confirm the results of earlier work that an off-center inclined
collision between two disk galaxies is almost certainly responsible for the
peculiar morphologies of this system. However, we have explored a wider set of
initial galaxy and collisional encounter parameters than previously, and have
found a relatively narrow range of parameters that reproduce all the major
morphologies of this system. The simulations suggest specific mechanisms for
the development of several unusual structures. We find that the complex gas
bridge has up to four distinct components, with gas contributed from two sides
of NGC 7715, as well as from NGC 7714. The observed gas-star offset in this
bridge is accounted for in the simulations by the dissipative evolution of the
gas. The models also indicate that the low surface brightness HI tail to the
far west of NGC 7714 is the end of the NGC 7715 countertail, curved behind the
two galaxies. Spectral evolutionary models of the NGC 7714 core by Lan\c{c}on
et al. suggest the possibility of multiple starbursts in the last 300 Myr. Our
hydrodynamic models suggest that bursts could be triggered by induced ring-like
waves, and a post-collision buildup of gas in the core of the galaxy.


title: The visibility of shell-type supernova remnants in gamma rays

abstract:
  The idea that the shocks from supernova remnants (SNR) expanding into the
interstellar medium (ISM) accelerate CR is still popular one but a number of
authors have drawn attention to the fact that the experimental evidence for the
presence of gamma rays from the expected interaction of CR with gas in the
remnant is poor. Indeed, it is claimed that many SNR are not `seen' in GeV or
TeV gamma rays, whereas `they should have been'.
  We have looked at this problem and we conclude that the idea of CR production
in SNR cannot be faulted in this way, if the evacuation of ambient gas by the
stellar wind of the progenitor star and, frequently, by associated earlier
close-by SN, is taken into account; such phenomena are expected for the
important Type II SN which result from very massive stars.
  Other SNR have, apparently, been seen and the interaction of SNR-accelerated
particles with adjacent molecular clouds has been deemed responsible. However,
we worry about this interpretation because of the slow progress of the SNR
shock through such clouds, although electron-effects may, indeed, contribute.
  This paper is devoted mainly to the visibility of nearby SNR in gamma rays
although many of the arguments also relate to remote SNR. For the nearby SNR
another problem enters the scene: the large angular spread of the remnant. It
is especially important for the old SNR, where cosmic rays have already
diffused to a large distance from the SNR center. We have also examined the
effect of the 'anomalous diffusion' of CR propagation in the non-homogeneous
interstellar medium on the visibility of SNR for gamma rays of different
energies.


title: Thermal-timescale mass transfer and magnetic CVs

abstract:
  We investigate the spin evolution of the unusual magnetic CV AE Aqr. As a
prototype for a potentially large population of CVs subject to a thermally
unstable phase of mass transfer, understanding its future is crucial. We
present a new definition of the magnetospheric radius in terms of the white
dwarf's spin period, and use this along with numerical simulations to follow
the spin evolution of AE Aqr. We also present preliminary SPH results
suggesting the existence of a stable propeller state. These results highlight
the complexity of mCVs and may provide am improved understanding of the
evolution of all types of CVs.


title: Secular Evolution of Spiral Galaxies

abstract:
  It is now a well established fact that galaxies undergo significant
morphological transformation during their lifetimes, manifesting as an
evolution along the Hubble sequence from the late to the early Hubble types.
The physical processes commonly believed to be responsible for this observed
evolution trend, i.e. the major and minor mergers, as well as gas accretion
under a barred potential, though demonstrated applicability to selected types
of galaxies, on the whole have failed to reproduce the most important
statistical and internal properties of galaxies. The secular evolution
mechanism reviewed in this paper has the potential to overcome most of the
known difficulties of the existing theories to provide a natural and coherent
explanation of the properties of present day as well as high-redshift galaxies.


title: The Stellar Content of M31's Bulge

abstract:
  In this paper we analyze the stellar populations present in M31 using nine
sets of adjacent HST-NICMOS Camera 1 and 2 fields with galactocentric distances
ranging from 2' to 20'. These infrared observations provide some of the highest
spatial resolution measurements of M31 to date; our data place tight
constraints on the maximum luminosities of stars in the bulge of M31. The tip
of the red giant branch is clearly visible at Mbol ~ -3.8, and the tip of the
asymptotic giant branch (AGB) extends to Mbol ~ -5. This AGB peak luminosity is
significantly fainter than previously claimed; through direct comparisons and
simulations we show that previous measurements were affected by image blending.
We do observe field-to-field variations in the luminosity functions, but
simulations show that these differences can be produced by blending in the
higher surface brightness fields. We conclude that the red giant branch of the
bulge of M31 is not measurably different from that of the Milky Way's bulge. We
also find an unusually high number of bright blueish stars (7.3/arcmin^2) which
appear to be Galactic foreground stars.


title: Relative Standard of Measurement and Supernova Data

abstract:
  We show that in the units of the relative Paris meter both the latest data on
the Supernova luminosity-distance -- redshift relation and primordial
nucleosynthesis are described by the dynamics of a homogeneous, massless scalar
field (Scalar Quintessence) in a nonexpanding universe.


title: Median Statistics and the Mass Density of the Universe

abstract:
  We use weighted mean and median statistics techniques to combine individual
estimates of Omega_m0, the present mean mass density in non-relativistic
matter, and determine the observed values and ranges of Omega_m0 from different
combinations of data. The derived weighted mean Omega_m0 values are not good
representatives of the individual measurements, under the assumptions of
Gaussianity and negligible correlation between the individual measurements.
This could mean that some observational error bars are under-estimated.
Discarding the most discrepant about 5% of the measurements generally
alleviates but does not completely resolve this problem. While the results
derived from the different combinations of data are not identical, they are
mostly consistent, and a reasonable summary of the median statistics analyses
is 0.2 <= Omega_m0 <= 0.35 at two standard deviations.


title: Understanding the PSCz Galaxy Power Spectrum with N-body Simulations

abstract:
  By comparing the PSCz galaxy power spectrum with the results of nested pure
dark matter N-body simulations, we try to understand how infrared-selected
galaxies populate dark-matter haloes, paying special attention to the method of
halo identification in the simulations. We thus test the hypothesis that
baryonic physics negligibly affects the distribution of galaxies down to the
smallest scales yet observed. We are successful in reproducing the PSCz power
spectrum on scales < ~40 h/Mpc, near our resolution limit, by imposing a
central density cut-off on simulated haloes, which gives a rough minimum mass
and circular velocity of haloes in which PSCz galaxies formed.


title: Cosmological Uses of Gamma-Ray Bursts

abstract:
  Studies of the cosmic gamma-ray bursts (GRBs) and their host galaxies are
starting to provide interesting or even unique new insights in observational
cosmology. GRBs represent a new way of identifying a population of star-forming
galaxies at cosmological redshifts. GRB hosts are broadly similar to the normal
field galaxy populations at comparable redshifts and magnitudes, and indicate
at most a mild luminosity evolution out to z ~ 1.5 - 2. GRB optical afterglows
seen in absorption provide a powerful new probe of the ISM in dense, central
regions of their host galaxies, complementary to the traditional studies using
QSO absorbers. Some GRB hosts are heavily obscured, and provide a new way to
select a population of cosmological sub-mm sources, and a novel constraint on
the total obscured fraction of star formation over the history of the universe.
Finally, detection of GRB afterglows at z > 6 may provide a unique way to probe
the primordial star formation, massive IMF, early IGM, and chemical enrichment
at the end of the cosmic reionization era.


title: Lensing Optical Depth for Substructure and Isolated Dark Matter Halos

abstract:
  Multiply-imaged quasar lenses can be used to constrain the substructure mass
fraction in galaxy-sized dark matter halos via anomalous flux ratios in lensed
images. The flux ratios, however, can be affected by both the substructure in
the lens halo and by isolated small-mass halos along the entire line-of-sight
to the lensed source. While lensing by dark matter clumps near the lens galaxy
is more efficient than elsewhere, the cumulative effect of all objects along
the line-of-sight could be significant. Here we estimate the potential
contribution of isolated clumps to the substructure lensing signal using a
simple model motivated by cosmological simulations. We find that the
contribution of isolated clumps to the total lensing optical depth ranges from
a few to tens percent, depending on assumptions and the particular
configuration of the lens. Therefore, although the contribution of isolated
clumps to the lensing signal is not dominant, it should not be neglected in
detailed analyses of substructure lensing. For the currently favored Lambda-CDM
model, the total calculated optical depth for lensing is high, tau ~ 0.2-20 and
could, therefore, naturally explain the high frequency of anomalous flux ratios
in observed lenses. The prediction, however, is highly sensitive to the spatial
distribution of substructure halos in the innermost regions of the lens halo,
which is still very uncertain. Therefore, constraints on the properties of the
substructure population or accurate cosmological constraints, such as the mass
of the warm dark matter particle, are difficult if not impossible to derive at
this point.


title:
The cosmological baryon density from the deuterium to hydrogen ratio
  towards QSO absorption systems: D/H towards Q1243+3047

abstract:
  We report the detection of Deuterium absorption at redshift 2.525659 towards
Q1243+3047. We describe improved methods to estimate the Deuterium to Hydrogen
abundance ratio (D/H) in absorption systems, including improved modeling of the
continuum level, the Ly-alpha forest and the velocity structure of the
absorption. Together with improved relative flux calibration, these methods
give D/H = 2.42^+0.35_-0.25 x 10^-5 cm^-2 from our Keck-I HIRES spectra of
Q1243+3047, where the error is from the uncertainty in the shape of the
continuum level and the amount of D absorption in a minor second component. The
measured D/H is likely the primordial value because the [O/H] = -2.79 +/- 0.05.
This absorption system has a neutral Hydrogen column density of 19.73 +/- 0.04
cm^-2, it shows five D lines and is mostly ionized. The best estimate of the
primordial D/H is 2.78^+0.44_-0.38 x 10^-5, from the log D/H values towards
five QSOs. The dispersion in the five values is larger than we expect from
their individual measurement errors and we suspect this is because some of
these errors were underestimated. We observe a trend in D/H with neutral H
column density that we also suspect is spurious. The D/H corresponds to a
baryon-to-photon ratio ETA = 5.9 +/- 0.5 x 10^-10 and a cosmological baryon
density Omega_b h^2 = 0.0214 +/- 0.0020 (9.3%) that agrees with values from the
pre-MAP measurements of the anisotropy of the Cosmic Microwave Background.


title:
The dark burst 010214 with BeppoSAX: possible variable absorption and
  jet X-ray emission

abstract:
  We report on the prompt and afterglow emission observations of the dark burst
GRB010214 with BeppoSAX. The prompt emission shows possible evidence of
variable absorption from N_H = 3.0^{+5.1}_{-2.0} x 10^23 cm-2 in the first 6 s
of the event to a value consistent with the Galactic column density (N_H^(G) =
2.66 x 10^20 cm-2) in the GRB direction. An X-ray afterglow emission in the
2-10 keV energy band was detected with BeppoSAX, but an analogue search at
lower wavelengths (optical, IR and radio) was unsuccessful. The X-ray afterglow
spectrum is consistent with a power-law with Galactic absorption. The light
curve shows a complex decay, if the tail of the prompt emission is assumed as
the onset of the afterglow: if the origin of the afterglow is coincident with
the GRB onset, a bump before ~ 3 x 10^4 s is inferred, while if the afterglow
is assumed to start later, a steepening of the power-law light curve at t ~ 3 x
10^4 s is deduced. We discuss these results in the light of the current models
of afterglows and the possible origin of the GRB darkness. Finally, we
tentatively derive an estimate of the burst redshift.


title:
A New Application of the Lunar Laser Retroreflectors: Searching for the
  "Local" Hubble Expansion

abstract:
  Precise measurements of the Earth-Moon distance by the lunar laser ranging
(LLR), which begun in the early 1970's, contributed significantly to geodesy,
geophysics, and lunar planetology, as well as enabled astrophysicists to
perform several fine tests of the relativistic gravitational field theory
(General Relativity). Yet another promising application of LLR arises just now
in the context of recent cosmological models, whose dynamics is substantially
affected by some kinds of the dark matter (or the so-called "dark energy")
uniformly distributed in space, and therefore should be accompanied by some
residual Hubble expansion at any spatial scales, particularly, in the
Earth-Moon system. The "local" Hubble expansion can be revealed by comparing
the rate of increase in the lunar semi-major axis measured by LLR (which should
be produced both by the well-known tidal exchange of angular momentum between
the Earth and Moon and the local Hubble expansion) with the same quantity
derived indirectly from astrometric data on the Earth's rotation deceleration
(which is produced only by the tidal interaction). Such analysis really points
to the discrepancy 1.3 cm/yr, which corresponds to the local Hubble constant
H_0^(loc) = 33 +/- 5 (km/s)/Mpc. This value is about two times less than at
intergalactic scales but many orders of magnitude greater than was predicted in
earlier theoretical works.


title:
Evidence for anisotropy in the distribution of short-lived gamma-ray
  bursts

abstract:
  Measurements of the two-point angular correlation function w(\theta) for 407
short gamma-ray bursts collected in the Current BATSE Catalogue reveal a ~2
\sigma deviation from isotropy on angular scales \theta ~ 2-4 degrees. Such an
anisotropy is not observed in the distribution of long gamma-ray bursts and
hints to the presence of repeated bursts for up to ~13% of the sources under
exam. However, the available data cannot exclude the signal as due to the
presence of large-scale structure. Under this assumption, the amplitude of the
observed w(\theta) is compatible with those derived for different populations
of galaxies up to redshifts ~0.5, result that suggests short gamma-ray bursts
to be relatively local sources.


title: Magnetic CVs in the UCT CCD CV Survey

abstract:
  An overview is given of all the magnetic CVs found in the UCT CCD CV Survey
(Woudt & Warner 2001, 2002, 2003a). We have identified eight new candidate
Intermediate Polars (IP), of which six are classical novae (RR Cha, DD Cir, AP
Cru, V697 Sco, V373 Sct, and RX J1039.7-0507). The two other candidate IPs are
Aqr1 (2236+0052) and RX J0944.5+0357. In addition, there are two probable
Polars, namely V351 Pup (= Nova Puppis 1991) and FIRST J102347.6+003841.


title:
FUSE Snap-Shot Survey of O VI Variability in the Winds of 66 OB-Type
  Stars

abstract:
  We have used the Far Ultraviolet Spectroscopic Explorer (FUSE) to conduct a
snap-shot survey of O VI variability in the winds of 66 OB-type stars in the
Galaxy and the Magellanic Clouds. These time series consist of two or three
observations separated by intervals ranging from a few days to several months.
Although these time series provide the bare minimum of information required to
detect variations, this survey demonstrates that the O VI doublet in the winds
of OB-type stars is variable on various scales both in time and velocity. For
spectral types from O3 to B1, 64% vary in time. At spectral types later than
B1, no wind variability is observed. This fraction represents a lower limit on
the true incidence of variability in the O VI wind lines, which is very common
and probably ubiquitous. The observed variations extend over several hundreds
of km/s of the wind profile and can be strong. The width over which the wind O
VI profile varies is only weakly correlated with the terminal velocity (\vinf),
but a significant correlation (close to a 1:1 relationship) is derived between
the maximum velocity of the variation and \vinf. High velocity O VI wind
absorption features (possibly related to the discrete absorption components
seen in other wind lines) are also observed in 46% of the cases for spectral
types from O3 to B0.5. These features are variable, but the nature of their
propagation cannot be determined from this survey. If X-rays can produce
sufficient O VI by Auger ionization of O VI, and the X-rays originate from
strong shocks in the wind, this study suggests that stronger shocks occur more
frequently near \vinf, causing an enhancement of O VI near \vinf.


title: Inflation versus Cyclic Predictions for Spectral Tilt

abstract:
  We present a simple, nearly model-independent estimate that yields the
predictions of the simplest inflationary and ekpyrotic/cyclic models for the
spectral tilt of the primordial density inhomogeneities. Remarkably, we find
that the simplest models yield an identical result: n_s is approximately 0.95.
For inflation, the same estimate predicts a ratio of tensor to scalar
contributions to the low multipoles of the microwave background anisotropy of
T/S=20%; the tensor contribution is negligible for ekpyrotic/cyclic models.


title: A New Approach to Turbulent Transport of a Mean Scalar

abstract:
  We develop a simple mean field approach to the transport of a passive scalar
for which the fundamental equation is a second order differential equation in
the transported quantity, not a first order equation. Triple correlations are
included, as they must be for any realistic description of turbulence. No
correlation time enters the theory, only an eddy turnover time. The approach is
simpler than standard approaches which incorporate triple correlations, but
more realistic than Gaussian or short correlation time closures which do not. A
similar approach has proven useful in magnetohydrodynamics.


title:
Role of shocked accretion flows in regulating the QPO of galactic black
  hole candidates

abstract:
  Using a generalized non-spherical, multi-transonic accretion flow model, we
analytically calculate the normalized QPO frequency ${\bar {\bf {\nu}}}_{qpo}$
of galactic black hole candidates in terms of dynamical flow variables and
self-consistently study the dependence of ${\bar {\bf {\nu}}}_{qpo}$ on such
variables. Our results are in fairly close agreement with the observed QPO
frequencies of GRS 1915+105. We find that ${\bar {\bf {\nu}}}_{qpo}$ is quite
sensitive to various parameters describing the black hole accretion flow
containing dissipative and non-dissipative shock waves. Thus the QPO phenomena
is, {\it indeed}, regulated by `shocked' black hole accretion, and, for the
first time, we establish a definitive connection between the QPO frequency and
the properties of advective BH accretion flows. This information may provide
the explanation of some important observations of galactic micro quasars.


title:
Global Anisotropy Versus Small-Scale Fluctuations in Neutrino Flux in
  Core-Collapse Supernova Explosions

abstract:
  Effects of small-scale fluctuations in the neutrino radiation on
core-collapse supernova explosions are examined. Through a parameter study with
a fixed radiation field of neutrinos, we find substantial differences between
the results of globally anisotropic neutrino radiation and those with
fluctuations. As the number of modes of fluctuations increases, the shock
positions, entropy distributions, and explosion energies approach those of
spherical explosion. We conclude that global anisotropy of the neutrino
radiation is the most effective mechanism of increasing the explosion energy
when the total neutrino luminosity is given. This supports the previous
statement on the explosion mechanism by Shimizu and coworkers.


title:
FTS Measurements of Submillimeter-Wave Atmospheric Opacity at Pampa la
  Bola III. Water Vapor, Liquid Water, and 183 GHz Water Vapor Line Opacities

abstract:
  Further analysis has been made on the millimeter and submillimeter-wave
(100-1600 GHz or 3 mm - 188 micron) atmospheric opacity data taken with the
Fourier Transform Spectrometer (FTS) at Pampa la Bola, 4800 m above sea level
in northern Chile, which is the site of the Atacama Large
Millimeter/submillimeter Array (ALMA). Time-sequence plots of millimeter and
submillimeter-wave opacities show similar variations to each other, except for
during the periods with liquid water (fog or clouds) in the atmosphere. Using
millimeter and submillimeter-wave opacity correlations under two conditions,
which are affected and not affected by liquid water, we succeeded to separate
the measured opacity into water vapor and liquid water opacity components. The
water vapor opacity shows good correlation with the 183 GHz water vapor line
opacity, which is also covered in the measured spectra. On the other hand, the
liquid water opacity and the 183 GHz line opacity show no correlation. Since
only the water vapor component is expected to affect the phase of
interferometers significantly, and the submillimeter-wave opacity is less
affected by the liquid water component, it may be possible to use the
submillimeter-wave opacity for a phase-correction of submillimeter
interferometers.


title: Multi-epoch HI line measurements of 4 southern pulsars

abstract:
  We have measured 21-cm absorption spectra in the direction of three southern
pulsars, PSRs B0736-40, B1451-68 and B1641-45, in three separate epochs spread
over 2.5 yr. We see no evidence for any changes in the absorption spectra over
this time span in spite of good velocity resolution and sensitivity. Towards
PSR B1641-45 we place an upper limit of 10^19 per cm^2 on the change in the
column density of the cold, neutral gas. In addition, we observed PSR B1557-50
and compared its HI absorption spectrum with spectra taken in 1980 and 1994. A
prominent deep absorption feature seen at -110 km/s in 1994 is weaker in 2000
and likely was not present at all in 1980. Using the standard interpretation
which links the distance traversed by the pulsar to a physical cloud size, this
results in a cloud size of ~1000 AU and density of 2x10^4 per cc, parameters
typical of those seen in other observations. These results are also consistent
with an alternative model by Deshpande (2000) who expects the largest
variations in optical depth to be seen against the longest time intervals.