title:
Unveiling the central parsec region of an AGN: the Circinus nucleus in
  the near infrared with the VLT

abstract:
  VLT J- to M\p-band adaptive optics observations of the Circinus Galaxy on
parsec scales resolve a central bright Ks-band source with a FWHM size of 1.9
$\pm$ 0.6 pc. This source is only visible at wavelengths longward of 1.6 $\mu$m
and coincides in position with the peak of the [Si VII]~2.48 $\mu$m coronal
line emission. With respect to the peak of the central optical emission, the
source is shifted by $\sim$ 0.15\arcsec (2.8 pc) to the south-east. Indeed, it
defines the vertex of a fairly collimated beam which extends for $\sim$ 10 pc,
and which is seen in both continuum light shortward of 1.6 $\mu$m and in
H$\alpha$ line emission. The source also lies at the center of a $\sim$ 19 pc
size [Si VII] ionization {\it bicone}.
  Identifying this source as the nucleus of Circinus, its size is compatible
with a putative parsec-scale torus. Its spectral energy distribution,
characterized by a prominent narrow peak, is compatible with a dust temperature
of 300 K. Hotter dust within a 1 pc radius of the center is not detected. The
AGN luminosity required to heat this dust is in the range of X-ray luminosities
that have been measured toward the central source. This in turn supports the
existence of highly obscuring material, with column densities of $10^{24}$
cm$^{-2}$, that must be located within 1 pc of the core.


title:
Gravitino production by primordial black hole evaporation and
  constraints on the inhomogeneity of the early Universe

abstract:
  In supergravity models, the evaporation of light Primordial Black Holes
(PBHs) should be a source of gravitinos. By considering this process, new
stringent limits are derived on the abundance of small black holes with initial
masses less than 10^9 g. In minimal supergravity, the subsequent decay of
evaporated gravitinos into cascades of non-equilibrium particles leads to the
formation of elements whose abundance is constrained by observations. In gauge
mediated supersymmetry breaking models, their density is required not to
overclose the Universe. As a result, cosmological models with substantial
inhomogeneities on small scales are excluded.


title: Cosmic strings in Bekenstein-type models

abstract:
  We study static cosmic string solutions in the context of Bekenstein-type
models. We show that there is a class of models of this type for which the
classical Nielsen-Olesen vortex is still a valid solution. However, in general
static string solutions in Bekenstein-type models strongly depart from the
standard Nielsen-Olesen solution with the electromagnetic energy concentrated
along the string core seeding spatial variations of the fine structure
constant, $\alpha$. We consider models with a generic gauge kinetic function
and show that equivalence principle constraints impose tight limits on the
allowed variations of $\alpha$ induced by string networks on cosmological
scales.


title:
The Binarity of Eta Carinae and its Similarity to Related Astrophysical
  Objects

abstract:
  I examine some aspects of the interaction between the massive star Eta
Carinae and its companion, in particular during the eclipse-like event, known
as the spectroscopic event or the shell event. The spectroscopic event is
thought to occur when near periastron passages the stellar companion induces
much higher mass loss rate from the primary star, and/or enters into a much
denser environment around the primary star. I find that enhanced mass loss rate
during periastron passages, if it occurs, might explain the high eccentricity
of the system. However, there is not yet a good model to explain the presumed
enhanced mass loss rate during periastron passages. In the region where the
winds from the two stars collide, a dense slow flow is formed, such that large
dust grains may be formed. Unlike the case during the 19th century Great
Eruption, the companion does not accrete mass during most of its orbital
motion. However, near periastron passages short accretion episodes may occur,
which may lead to pulsed ejection of two jets by the companion. The companion
may ionize a non-negligible region in its surrounding, resembling the situation
in symbiotic systems. I discuss the relation of some of these processes to
other astrophysical objects, by that incorporating Eta Car to a large class of
astrophysical bipolar nebulae.


title: Understanding the IMF

abstract:
  It is suggested that the thermal physics of star-forming clouds may play a
more important role than has usually been recognized in the origin of the
stellar IMF and in determining a characteristic mass scale. The importance of
the thermal physics has been clearly demonstrated for the formation of the
first stars in the universe, where it is well understood and results in cooling
to a characteristic minimum temperature at a preferred density, and hence in a
characteristic scale for fragmentation. In present-day star-forming clouds, an
analogous situation may exist in that at low densities the temperature is
expected to decrease with increasing density, reaching a minimum when the gas
becomes thermally coupled to the dust and then rising slowly at higher
densities. A minimum temperature of about 5 K is predicted to occur at a
density of the order of 10^(-18) g cm^(-3), and at this point the Jeans mass is
about 0.3 solar masses, similar to the mass at which the IMF peaks. If most of
the fragmentation in star-forming clouds occurs in filaments, as is suggested
by many simulations as well as by observations, fragmentation seems likely to
occur preferentially at the density where the temperature reaches a minimum,
and the Jeans mass at this point may then determine a characteristic scale for
fragmentation and hence a preferred stellar mass.


title:
Data reduction methods for single-mode optical interferometry -
  Application to the VLTI two-telescopes beam combiner VINCI

abstract:
  The interferometric data processing methods that we describe in this paper
use a number of innovative techniques. In particular, the implementation of the
wavelet transform allows us to obtain a good immunity of the fringe processing
to false detections and large amplitude perturbations by the atmospheric piston
effect, through a careful, automated selection of the interferograms. To
demonstrate the data reduction procedure, we describe the processing and
calibration of a sample of stellar data from the VINCI beam combiner. Starting
from the raw data, we derive the angular diameter of the dwarf star Alpha Cen
A. Although these methods have been developed specifically for VINCI, they are
easily applicable to other single-mode beam combiners, and to spectrally
dispersed fringes.


title:
Dynamics and Heating of the Magnetic Network on the Sun: Efficiency of
  mode transformation

abstract:
  We aim to identify the physical processes which occur in the magnetic network
of the chromosphere and which contribute to its dynamics and heating.
Specifically, we study the propagation of transverse (kink) MHD waves which are
impulsively excited in flux tubes through footpoint motions. When these waves
travel upwards, they get partially converted to longitudinal waves through
nonlinear effects (mode coupling). By solving the nonlinear, time-dependent MHD
equations we find that significant longitudinal wave generation occurs in the
photosphere typically for Mach numbers as low as 0.2 and that the onset of
shock formation occurs at heights of about 600 km above the photospheric base.
We also investigate the compressional heating due to longitudinal waves and the
efficiency of mode coupling for various values of the plasma $\beta$, that
parameterises the magnetic field strength in the network. We find that this
efficiency is maximum for field strengths corresponding to $\beta\approx 0.2$,
when the kink and tube wave speeds are almost identical. This can have
interesting observational implications. Furthermore, we find that even when the
two speeds are different, once shock formation occurs, the longitudinal and
transverse shocks exhibit strong mode coupling.


title:
Testing blend scenarios for extrasolar transiting planet candidates. I.
  -- OGLE-TR-33: a false positive

abstract:
  We report high-resolution spectroscopic follow-up observations of the faint
transiting planet candidate OGLE-TR-33 (V = 14.7), located in the direction of
the Galactic center. Small changes in the radial velocity of the star were
detected that suggested initially the presence of a large planet or brown dwarf
in orbit. However, further analysis revealed spectral line asymmetries that
change in phase with the 1.95-day period, casting doubt on those measurements.
These asymmetries make it more likely that the transit-like events in the light
curve are the result of contamination from the light of an eclipsing binary
along the same line of sight (referred to as a "blend"). We performed detailed
simulations in which we generated synthetic light curves resulting from such
blend scenarios and fitted them to the measured light curve. Guided by these
fits and the inferred properties of the stars, we uncovered a second set of
lines in our spectra that correspond to the primary of the eclipsing binary and
explain the asymmetries. Using all the constraints from spectroscopy we were
then able to construct a model that satisfies all the observations, and to
characterize the three stars based on model isochrones. OGLE-TR-33 is fully
consistent with being a hierarchical triple system composed of a slightly
evolved F6 star (the brighter object) near the end of its main-sequence phase,
and an eclipsing binary with a K7-M0 star orbiting an F4 star. The application
to OGLE-TR-33 of the formalism developed to fit light curves of transit
candidates illustrates the power of such simulations for predicting additional
properties of the blend and for guiding further observations that may serve to
confirm that scenario, thereby ruling out a planet. Tests such as this can be
very important for validating faint candidates.


title: Low Frequency Observations of a Head-Tail Radio Source

abstract:
  We have mapped the head-tail radio galaxy, 3C 129 at 240 and 610 MHz using
the GMRT and studied the detailed morphology and spectral index variations in
this object. This is the first attempt to observe a sample of head-tail sources
at low frequencies. We find weak spectral steepening as we go away from the
head along the jet. The Crosspiece has a spectral index of 0.9 (S$_{\nu}
\propto \nu^{-\alpha}$) and is flatter than the spectral index estimated by
Lane et al. (2002). We also see a low surface brightness, diffuse feature at
240 MHz and could be a possible radio relic candidate (see Figure).


title:
RefSponse: A Literature Evaluation System for the Professional
  Astrophysics Community

abstract:
  We describe an implementation of a semi-automated review system for the
astrophysics literature. Registered users identify names under which they
publish, and provide scores for individual papers of their choosing. Scores are
held confidentially, and combined in a weighted average grade for each paper.
The grade is divided among the co-authors as assigned credit. The credit
accumulated by each user (their ``mass'') provides the weight by which their
score is averaged into papers' grades. Thus, papers' grades and users' masses
are mutually dependent and evolve in time as scores are added. Likewise, a
user's influence on the grade of a paper is determined from the perceived
original scientific contribution of all the user's previous papers. The
implementation, called RefSponse -- currently hosted at
http://bororo.physics.mcgill.ca -- includes papers in astro-ph, the ApJ, AJ,
A&A, MNRAS, PASP, PASJ, New Astronomy, Nature, ARA&A, Phys. Rev. Letters, Phys.
Rev. D. and Acta Astronomica from 1965 to the present, making extensive use of
the NASA/ADS abstract server. We describe some of the possible utilities of
this system in enabling progress in the field.


title: Iron Abundance Diagnostics in High-Redshift QSOs

abstract:
  The abundance of alpha-process elements such as magnesium and carbon relative
to iron measured from the broad emission lines of QSOs can serve as a
diagnostic of the star formation and chemical enrichment histories of their
host galaxies.
  We investigate the relationship between Fe/Mg and Fe/C abundance ratios and
the resulting Fe II / Mg II 2800A and Fe II / 1900A-blend flux ratios, both of
which have been measured in QSOs out to redshifts of approximately six. Using a
galactic chemical evolution model based on a starburst in a giant elliptical
galaxy, we find that these flux ratios are good tracers of the chemical
enrichment of the nuclei. However, the values of these ratios measured in
objects at redshifts of approximately six suggest that iron enrichment has
occurred more rapidly in these objects than predicted by the assumed elliptical
starburst model, under currently favored cosmologies.


title:
The accreting neutron stars are quasars, and the universe does not
  expand

abstract:
  The reliable theory of the evolution of heavy stars predicts the existence of
a type of neutron stars which accrete a cloud of dirty hydrogen (accretors).
Although they are very small (some hundreds of kilometres), the accretors
should be easily observable because the accretion raises the surface
temperature over 1 000 000 K, but they are never detected. The reason of this
failure is a misunderstanding of the spectroscopy of hydrogen crossed by a
powerful beam of short wavelengths light. Except very close to the surface,
hydrogen is mostly heated by a Lyman absorption improved by a parametric
frequency shift due to excited atomic hydrogen, so that this absorption
stabilises the temperature between the limits of ionisation and dimerisation. A
powerful radio emission may produce an extra ionisation where the pressure is
convenient. The combination of Lyman absorptions and redshifts produces an
instability which chains Lyman absorption patterns : when a redshifted Lyman
absorbed line coincides with a Lyman line, all absorption lines of the gas are
written into the spectrum. Thus all characteristics of the complex spectrum of
a quasar are generated, so that observed accretors are named quasars, and the
origin of the intrinsic redshifts is found. The lack of redshifts of the
variations of luminosity of stars and quasars shows that the "cosmological
redshifts" result from the parametric frequency shift, so that the universe
does not expand.


title:
Multi-Phase Galaxy Formation: High Velocity Clouds and the Missing
  Baryon Problem

abstract:
  The standard treatment of cooling in Cold Dark Matter halos assumes that all
of the gas within a ``cooling radius'' cools and contracts monolithically to
fuel galaxy formation. Here we take into account the expectation that the hot
gas in galactic halos is thermally unstable and prone to fragmentation during
cooling and show that the implications are more far-reaching than previously
expected: allowing multi-phase cooling fundamentally alters expectations about
gas infall in halos and naturally explains the bright-end cutoff in the galaxy
luminosity function. We argue that cooling should proceed via the formation of
high-density, 10^4 K clouds, pressure-confined within a hot gas background. The
background medium has a low density, and can survive as a stable corona with a
long cooling time. The fraction of baryons contained in the residual hot core
grows with halo mass because the cooling density increases, and this leads to
an upper-mass limit in quiescent, non-merged galaxies of ~10^11 Msun. In this
scenario, galaxy formation is fueled by the infall of pressure-supported
clouds. For Milky-Way-size systems, clouds of mass ~ 5x10^6 Msun that formed or
merged within the last several Gyrs should still exist as a residual population
in the halo, with a total mass in clouds of ~ 2 x 10^10 Msun. The mass of the
Milky Way galaxy is explained naturally in this model, and is a factor of two
smaller than would result in the standard treatment without feedback. We expect
clouds in galactic halos to be ~ 1 kpc in size and to extend ~150 kpc from
galactic centers. The predicted properties of clouds match well the observed
radial velocities, angular sizes, column densities, and velocity widths of High
Velocity Clouds around our Galaxy. The clouds also explain high-ion absorption
systems at z<1.


title:
Interpreting the Relationship Between Galaxy Luminosity, Color and
  Environment

abstract:
  We study the relationship between galaxy luminosity, color, and environment
in a cosmological simulation of galaxy formation. We compare the predicted
relationship with that found for SDSS galaxies and find that the model
successfully predicts most of the qualitative features seen in the data, but
also shows some interesting differences. Specifically, the simulation predicts
that the local density around bright red galaxies is a strong increasing
function of luminosity, but does not depend much on color at fixed luminosity.
Moreover, we show that this is due to central galaxies in dark matter halos
whose baryonic masses correlate strongly with halo mass. The simulation also
predicts that the local density around blue galaxies is a strong increasing
function of color, but does not depend much on luminosity at fixed color. We
show that this is due to satellite galaxies in halos whose stellar ages
correlate with halo mass. Finally, the simulation fails to predict the
luminosity dependence of environment observed around low luminosity red
galaxies. However, we show that this is most likely due to the simulation's
limited resolution. A study of a higher resolution, smaller volume simulation
suggests that this dependence is caused by the fact that all low luminosity red
galaxies are satellites in massive halos, whereas intermediate luminosity red
galaxies are a mixture of satellites in massive halos and central galaxies in
less massive halos.


title: The Parallax, Mass and Age of the PSR J2145-0750 binary system

abstract:
  We present results of timing measurements of the binary millisecond pulsar
PSR J2145-0750. Combining timing data obtained with the Effelsberg and Lovell
radio telescopes we measure a significant timing parallax of 2.0(6) mas placing
the system at 500 pc distance to the solar system. The detected secular change
of the projected semi-major axis of the orbit $\dot x=1.8(6)\times 10^{-14}$
lt-s s$^{-1}$, where $x=(a_{\rm p}\sin i)/c$, is caused by the proper motion of
the system. With this measurement we can constrain the orbital inclination
angle to $i<61\degr$, with a median likelihood value of $46\degr$ which is
consistent with results from polarimetric studies of the pulsar magnetosphere.
This constraint together with the non-detection of Shapiro delay rules out
certain combinations of the companion mass, $m_2$, and the inclination, $i$.
For typical neutron star masses and using optical observations of the
carbon/oxygen-core white dwarf we derive a mass range for the companion of $0.7
M_\odot\leq m_2\leq 1.0 M_\odot$. We apply evolutionary white dwarf cooling
models to revisit the cooling age of the companion. Our analysis reveals that
the companion has an effective temperature of $T_{\rm eff}=5750\pm600$ K and a
cooling age of $\tau_{\rm cool}=3.6(2)$ Gyr, which is roughly a factor of three
lower than the pulsar's characteristic age of 10.4 Gyr. The cooling age implies
an initial spin period of $P_0=13.0(5)$ ms, which is very close to the current
period.


title: Observational signatures of the weak lensing magnification of supernovae

abstract:
  Due to the deflection of light by density fluctuations along the line of
sight, weak lensing is an unavoidable systematic uncertainty in the use of type
Ia supernovae (SNe Ia) as cosmological distance indicators. We derive the
expected weak lensing signatures of SNe Ia by convolving the intrinsic
distribution in SN Ia peak luminosity with magnification distributions of point
sources. We analyze current SN Ia data, and find marginal evidence for weak
lensing effects. The statistics is poor because of the small number of observed
SNe Ia. Future observational data will allow unambiguous detection of the weak
lensing effect of SNe Ia. The observational signatures of weak lensing of SNe
Ia that we have derived provide useful templates with which future data can be
compared.


title: A New Contributor to Chemical Evolution in High-Redshift Galaxies

abstract:
  The recent discovery of a new population of stars exhibiting unusual
elemental abundance patterns characterized by enhanced Ti to Ga elements and
low alpha and n-capture elements suggests the contribution of a new class of
supernovae, probably a kind of Type Ia supernovae associated with close binary
evolution. The role of these supernovae in chemical evolution is negligible in
normal galaxies that undergo moderate star formation such as our own. Thus,
while the frequency of occurrence would be too low to detect in low-redshift
galaxies, it may represent a prominent population in high-redshift objects such
as early epoch massive elliptical galaxies and QSOs. The chemical contributor
of this proposed type of supernovae in combination with recognized supernovae
is shown to be compatible with the recent observational features in the distant
universe, successfully reproducing the Type II supernovae-like abundance
pattern with enhancement of Ga and Ge in the gas of newborn massive galaxies
and high iron abundances in QSOs even at redshifts of around 6.


title: The Evolution of Galaxies in and around Clusters at High-Redshift

abstract:
  In this paper, we focus on ram-pressure stripping and evaporation of disk
galaxies in and around a cluster. We show that the evolution of the disk
surface density affects the efficiency of ram-pressure stripping of galaxies at
z>~1. We also consider the saturation of thermal conduction in detail and show
that it cannot be ignored at larger radii of a cluster, which makes the
time-scale of the evaporation larger. Both the ram-pressure stripping and
evaporation could affect the evolution of galaxies even around a cluster. In
particular, the observed gradual decline of the star-formation rates of
galaxies in and around clusters could be explained by evaporation without
resorting to speculative strangulation (stripping of warm gas in galactic
halos).


title: Chandra X-ray Analysis of Galaxy Cluster A168

abstract:
  We present Chandra X-ray observations of galaxy cluster A168 (z=0.045). Two
X-ray peaks with a projected distance of 676 kpc are found to be located close
to two dominant galaxies, respectively. Both peaks are significantly offset
from the peak of the number density distribution of galaxies. This suggests
that A168 consists of two subclusters, a northern subcluster (A168N) and a
southern subcluster (A168S). Further X-ray imaging analysis reveals that (1)
the X-ray isophotes surrounding the two X-ray peaks are heavily distorted, (2)
an elongated and ontinuous filament connects the two X-ray peaks. These suggest
that strong interactions have occurred between the two subclusters. Spectral
analysis shows that A168 has a mean temperature of 2.53 +/- 0.09 keV and a mean
metallicity of 0.31 +/- 0.04 Z_{solar}. The metallicity is roughly a constant
across the cluster but the temperature shows some systematic variations. Most
X-ray, optical and radio properties of A168 are consistent with it being an
off-axis merger several Gyrs after a core passage, although detailed numerical
simulations are required to see whether the observed properties, in particular
the significant offset between the optical and X-ray centers, can be reproduced
in such a scenario.


title: Embedded Star Clusters in the W51 Giant Molecular Cloud

abstract:
  We present sub-arcsecond (0.35"-0.9"), near-infrared J,H,K band photometric
observations of six fields along the W51 Giant Molecular Cloud (W51 GMC). Our
observations reveal four new, embedded clusters and provide a new
high-resolution (0.35") view of the W51IRS2 (G49.5-0.4) region. The cluster
associated with G48.9-0.3 is found to be a double cluster enclosed in a nest of
near-infrared nebulosity. We construct stellar surface density maps for four
major clusters in the W51 GMC. These unveil the underlying hierarchical
structure. Color-color and color-magnitude diagrams for each of these clusters
show clear differences in the embedded stellar populations and indicate the
relative ages of these clusters. In particular, the clusters associated with
the HII regions G48.9-0.3 and G49.0-0.3 are found to have a high fraction of
YSOs and are therefore considered the youngest of all the near-infrared
clusters in the W51 GMC. The estimated masses of the individual clusters, when
summed, yield a total stellar mass of ~10^4 Msun in the W51 GMC, implying a
star formation efficiency of 5-10%. These results in comparision with the CO
observations of the W51 GMC, suggest for the first time, that star formation in
the W51 GMC is likely triggered by a galactic spiral density wave.


title: An Extinction Threshold for Protostellar Cores in Ophiuchus

abstract:
  We have observed continuum emission at lambda = 850 microns over ~4 square
degrees of the Ophiuchus star-forming cloud using SCUBA on the JCMT, producing
a submillimetre continuum map twenty times larger than previous Ophiuchus
surveys. Our sensitivity is 40 mJ/beam, a factor of ~2 less sensitive than
earlier maps. Using an automated identification algorithm, we detect 100
candidate objects. Only two new objects are detected outside the boundary of
previous maps, despite the much wider area surveyed. We compare the
submillimetre continuum map with a map of visual extinction across the
Ophiuchus cloud derived using a combination of 2MASS and R-band data. The total
mass in submillimetre objects is ~ 50 Msun compared with ~ 2000 Msun in
observed cloud mass estimated from the extinction. The submillimetre objects
represent only 2.5% of the cloud mass. A clear association is seen between the
locations of detected submillimetre objects and high visual extinction, with no
objects detected at A_V<7 magnitudes. Using the extinction map, we estimate
pressures within the cloud from P/k ~2x10^5 cm^-3 K in the less-extincted
regions to P/k ~2x10^6 cm^-3 K at the cloud centre. Given our sensitivities,
cold (T_d ~15K) clumps supported by thermal pressure, had they existed, should
have been detected throughout the majority of the map. Such objects may not be
present at low A_V because they may form only where A_V > 15, by some mechanism
(e.g., loss of non-thermal support).


title:
Propagation of Ultra-High Energy Cosmic Rays in Extragalactic Magnetic
  Fields

abstract:
  In this paper we will discuss the problem of Ultra High Energy Cosmic Rays
(UHECR) and show that the idea of a Single Source Model established by Erlykin
and Wolfendale (1997) to explain the features seen in cosmic ray energy spectra
around the 10**15 eV region can be successfully applied also for the much
higher energies. The propagation of UHECR (of energies higher than 10**19 eV)
in extragalactic magnetic fields can no longer be described as a random walk
(diffusion) process and the transition to rectilinear propagation gives a
possible explanation for the so-called Greisen-Zatzepin-Kuzmin (GZK) cut-off
which still remains an open question after almost 40 years. A transient "single
source" located at a particular distance and producing UHECR for a finite time
is the proposed solution.


title: Chemical Abundances of Planetary Nebulae in M33

abstract:
  Using spectroscopic data presented in Magrini et al. (2003), we have analyzed
with the photoionization code CLOUDY 94.00 (Ferland et al. 1998) 11 Planetary
Nebulae belonging to the spiral galaxy M 33. Central star temperatures and
nebular parameters have been determined. In particular the chemical abundances
of He/H, O/H, N/H, Ar/H, and S/H have been measured and compared with values
obtained via the Ionization Correction Factors (ICFs) method, when available.
Chemical abundance relationships have been investigated; in particular, a
correlation between N/H and N/O similar to the Galactic one (Henry 1989), and a
feeble anti-correlation between O/H and N/O have been found.
  A gradient in O/H across the disc of M~33 is indicatively consistent with the
one found from HII regions in this galaxy (Vilchez et al 1988). Further studies
in the more external parts of M~33 are however needed to ascertain this point.
The present result shows that oxygen and helium abundances (with lower accuracy
also nitrogen, argon and sulphur) can be actually estimated from the brightest
PNe of a galaxy, even if the electron temperature cannot be measured. We also
found that the oxygen abundance is quite independent of the absolute magnitude
of the PN and consequently the brightest PNe are representative of the whole PN
population. This represents an important tool to measure the metallicity of
galaxies at the time of the formation of PNe progenitors.


title:
The effects of X-ray photoionization and heating on the structure of
  circumstellar discs

abstract:
  We present the results of a theoretical study investigating the effects of
photoionization and heating by X-rays on discs around low-mass stars. In
particular we address the question of whether or not X-rays can drive a disc
wind. First, we construct a 1-dimensional ``quasi-hydrostatic'' model, which
solves for the vertical structure introduced by X-ray heating. We consider
uniform X-ray illumination of the disc, but the X-ray fluxes required to heat
the disc significantly are much greater than those seen by recent observations.
When the model is extended to consider heating from a central X-ray source we
find that the 1-dimensional model is only valid very close to the star. We
extend our analysis to consider a simple 2-dimensional model, treating the disc
as a two-layered structure and solving for its density profile
self-consistently. For T Tauri stars we are able to set a crude upper limit on
the mass-loss rate that can be driven by X-ray photoevaporation, with a value
of ~10^-13 g/cm^2/s. Our model is designed to maximise this value, and most
likely over-estimates it significantly. However we still find a mass-loss rate
which is less than that found in studies of ultraviolet photoevaporation. We
conclude that in the presence of a significant UV field, X-ray driven disc
winds are unlikely to play a significant role in the evolution of discs around
low-mass stars.


title:
Electron Temperatures in W51 Complex from High Resolution, Low Frequency
  Radio Observations

abstract:
  W51 is a giant radio complex lying along the tangent to the Sagitarius arm at
a distance of about 7kpc from Sun, with an extension of about 1deg in the sky.
It is divided into three components A,B,C where W51A and W51B consist of many
compact HII regions while W51C is a supernova remnant. We have made continuum
radio observations of these HII regions of the W51 complex at 240,610,1060,1400
MHz using GMRT with lower resolution 20''x15'' at the lowest frequency. The
observed spectra of the prominent thermal subcomponents of W51 have been fitted
to a free-free emission spectrum and their physical properties like electron
temperatures and emission measures have been estimated. The electron
temperatures from continuum spectra are found to be lower than the temperatures
reported from radio recombination line (RRL) studies of these HII regions
indicating the need for a filling factor even at this resolution. Also, the
observed brightness at 240MHz is found to be higher than expected from the best
fits suggesting the need for a multicomponent model for the region.


title:
Deep Near Infrared Imaging toward Vela Molecular Ridge C - 1: A
  Remarkable Embedded Cluster in RCW 36 -

abstract:
  We present deep near-infrared (J, H, Ks) images toward an embedded cluster
which lies in a C18O clump in the cloud C of the Vela Molecular Ridge. This
cluster has at least ~ 350 members and a radius of ~ 0.5 pc. The stellar
surface number density is approximately 3000 stars pc^-2 in the central 0.1 pc
x 0.1 pc region of the cluster. This is much higher than most of the young
clusters within 1 kpc of the Sun. From the comparison of the luminosity
function and near-infrared excess fraction with those of other embedded
clusters, we estimate that the age of this cluster is approximately 2-3 Myr.
This cluster exhibits an excess of brighter stars in its central region, from
which we conclude that the more massive stars are located near the cluster
center.


title: The structure of Onsala 1 star forming region

abstract:
  We present new high-sensitivity high-resolution mm-wave observations of the
Onsala 1 ultra-compact HII region that bring to light the internal structure of
this massive star forming cloud. The 1.2 mm continuum map obtained with the
IRAM 30-m radiotelescope (~11" resolution) shows a centrally peaked
condensation of 1' size (~0.5 pc at the assumed distance of 1.8 kpc) which has
been further investigated at higher resolution in the 3 mm continuum and in the
emission lines of H13CO+ J=1--0 and SiO J=2--1 with the IRAM Plateau de Bure
interferometer. The 3 mm data, with a resolution of ~5" X 4", displays a
unresolved continuum source at the peak of the extended 1.2 mm emission and
closely associated with the ultra-compact HII region. The H13CO+ map traces the
central condensation in good agreement with previous NH_3 maps of Zheng et al.
(1985). However, the velocity field of this central condensation, which was
previously thought to arise in a rapidly rotating structure, is better
explained in terms of the dense and compact component of a bipolar outflow.
This interpretation is confirmed by SiO and CO observations of the full region.
In fact, our new SiO data unveils the presence of multiple (at least 4)
outflows in the region. In particular, there is an important center of outflow
activity in the region at about 1' north of the UCHII region. Indeed the
different outflows are related to different members of the Onsala 1 cluster.
The data presented here support a scenario in which the phases of massive star
formation begin much later in the evolution of a cluster and/or UCHII region
last for much longer than 10^5 yrs.


title:
Virgo High-Resolution CO Survey IV. Spiral-Driven Gas Dynamics in the
  Non-Barred Seyfert Galaxy NGC 4501

abstract:
  We report on high-resolution interferometer observations of the 12CO(J=1-0)
emission in the central 5 kpc region of the Seyfert 2 galaxy NGC 4501. The
observations were made using the Nobeyama Millimeter Array during a long-term
CO line survey of Virgo spirals. The major features are: (1) a nuclear
concentration with a radius of r~5'' (390 pc), which is resolved into double
peaks, and (2) spiral arms which extend out from the nuclear region. The
nuclear component has a mass of 1.3x10^8 Mo, which corresponds to ~3.5% of the
dynamical mass, and shows a slight non-circular motion. The double peaks are
separated by ~4''.7. (370 pc), and located on the root of optical spiral arms
in a HST image. The gas arms are associated with the spiral dust lanes, and are
linked to the central double peaks. The non-circular motions along the
molecular arms indicate the fact that the gas is driven by the density wave,
rather than the stochastic processes. We calculated the gas cloud orbits in a
stellar spiral potential, and explained the observed CO spiral arms and
non-circular motions. We suggest that the central gas condensation arises from
spiral-driven gas transfer. We estimated and compared the effect of two
possible mechanisms of angular-momentum transfer: galactic shock, and
gravitational torques. We discuss that the galactic shock is dominant.


title: Extended Coronal Emission Lines in Active Galactic Nuclei

abstract:
  VLT and NTT spectra are used to examine the nuclear and extended coronal line
emission in a sample of well-known Seyfert 1 and 2 galaxies. The excellent
spatial resolution obtained with VLT allowed us to map [SiVI] 1.963 $\mu$m and
[SiVII] 2.48 $\mu$m on scales of up to 20 pc. Coronal line emission, extended
to distances of $\sim$100 pc, is detected in some of the lines analyzed,
particularly in [FeX] 6374\AA, [FeXI] 7891\AA, and [SiVII] 2.48$\mu$m. Most
coronal lines are strongly asymmetric towards the blue and broader than
low-ionization lines. This result is particularly important for Circinus, where
previous observations had failed at detecting larger widths for high-ionization
lines. Photoionization models are used to investigate the physical conditions
and continuum luminosities necessary to produced the observed coronal emission.
We found that an ionization parameter U> 0.10 is necessary to reproduce the
observations, although the clouds should be located at distances < 30 pc.


title:
Searching for radiative pumping lines of OH masers: II. The 53.3um
  absorption line towards 1612MHz OH maser sources

abstract:
  This paper analyzes the 53.3um line in the ISO LWS spectra towards a similar
sample of OH/IR sources. We find 137 LWS spectra covering 53.3um and associated
with 47 galactic OH/IR sources. Ten of these galactic OH/IR sources are found
to show and another 5 ones tentatively show the 53.3um absorption while another
7 sources highly probably do not show this line. The source class is found to
be correlated with the type of spectral profile: red supergiants (RSGs) and AGB
stars tend to show strong blue-shifted filling emission in their 53.3um
absorption line profiles while HII regions tend to show a weak red-shifted
filling emission in the line profile. GC sources and megamasers do not show
filling emission feature. It is argued that the filling emission might be the
manifestation of an unresolved half emission half absorption profile of the
53.3um doublet. The 53.3 to 34.6um equivalent width (EW) ratio is close to
unity for RSGs but much larger than unity for GC sources and megamasers while H
II regions only show the 53.3um line. The pump rate defined as maser to IR
photon flux ratio is approximately 5% for RSGs. The pump rates of GC sources
are three order of magnitude smaller. Both the large 53.3 to 34.6um EW ratio
and the small pump rate of the GC OH masers reflect that the two detected
`pumping lines' in these sources are actually of interstellar origin. The pump
rate of Arp 220 is 32%--much larger than that of RSGs, which indicates that the
contribution of other pumping mechanisms to this megamaser is important.


title: A thin ring model for the OH megamaser in IIIZw35

abstract:
  We present a model for the OH megamaser emission in the starburst galaxy
IIIZw35. The observed diffuse and compact OH maser components in this source
are explained by a single phase of unsaturated clumpy gas distributed in a thin
ring structure and amplifying background continuum. We emphasize the importance
of clumpiness in the OH masing medium, an effect that has not been fully
appreciated previously.
  The model explains why multiple bright spots are seen only at the ring
tangents while smoother emission is found elsewhere. Both the observed velocity
gradients and the line to continuum ratios around the ring enquire a geometry
where most of the seed photons come from a continuum emission which lies
outside the OH ring. To explain both the OH and continuum brightness, free-free
absorbing gas is required along the ring axis to partially absorb the far side
of the ring. It is proposed that the required geometry arises from an inwardly
propagating ring of starburst activity.


title: The Age-Activity-Rotation Relationship in Solar-Type Stars

abstract:
  Measured from high-resolution spectra, we present Ca II K line chromospheric
fluxes in 35 G dwarf stars of 5 open clusters to determine the
age-activity-rotation relationship from the young Hyades and Praesepe (0.6 Gyr)
to the old M 67 (~ 4.5 Gyr) through the two intermediate age clusters IC 4651
and NGC 3680 (~ 1.7 Gyr). Our data show that a dramatic decrease in
chromospheric activity takes place among solar stars between the Hyades and the
IC4651 age, in about 1 Gyr. Afterwards, activity remains virtually constant for
more than 3 Gyr. We briefly investigate the impact of this result on the age
determinations of field G dwarfs in the solar neighborhood; the two main
conclusions are that a consistent group of 'young' stars (i.e. as active as
Hyades stars) is present, and that it is virtually impossible to give accurate
chromospheric ages for stars older than ~ 2 Gyr. The observed abrupt decline in
activity explains very well the Vaughan-Preston gap.


title: New Constraints on Dark Energy

abstract:
  New Cosmic Microwave Background, Galaxy Clustering and Supernovae type Ia
data are increasingly constraining the dark energy component of our Universe.
While the cosmological constant scenario remains consistent with these new
tight constraints, the data does not rule out the possibility that the equation
of state parameter is less than -1.


title: The parsec scale region of Active Galactic Nuclei in the IR

abstract:
  First results from the AGN-Heidelberg program aimed at spatially resolving
the central pc region of the closest Active Galactic Nuclei are presented. The
core region of prototype active nuclei are clearly unveiled at IR waves and at
distances from the nucleus - few pc- where circumnuclear starforming regions
appear not to be present. Within that perspective, classical active nuclei as
Circinus and NGC 1097, reveal with unprecedented detail clear channels of
material being driven to the core whereas others as Centaurus A and NGC 1566,
show a "clean" core environment. At the very center, a central compact region
of about 2 pc scale is resolved in Circinus but not in the other cases
challenging thus the universal presence of the putative obscuring torus.


title:
Testing the correlations between ultra-high-energy cosmic rays and BL
  Lac type objects with HiRes stereoscopic data

abstract:
  Previously suggested correlations of BL Lac type objects with the arrival
directions of the ultra-high-energy cosmic ray primaries are tested by making
use of the HiRes stereoscopic data. The results of the study support the
conclusion that BL Lacs may be the cosmic ray sources and suggest the presence
of a small (a few percent) fraction of neutral primaries at E>10^{19} eV.


title: Hubble Space Telescope Science Metrics

abstract:
  Since its launch in April 1990, the Hubble Space Telescope (HST) has produced
an increasing flow of scientific results. The large number of refereed
publications based on HST data allows a detailed evaluation of the
effectiveness of this observatory and of its scientific programs. This paper
presents the results of selected science metrics related to paper counts,
citation counts, citation history, high-impact papers, and the most productive
programs and most cited papers, through the end of 2003. All these indicators
point towards the high-quality scientific impact of HST.


title:
A Comparison of Intermediate Mass Black Hole Candidate ULXs and
  Stellar-Mass Black Holes

abstract:
  Cool thermal emission components have recently been revealed in the X-ray
spectra of a small number of ultra-luminous X-ray (ULX) sources with L_X > 1
E+40 erg/s in nearby galaxies. These components can be well fitted with
accretion disk models, with temperatures approximately 5-10 times lower than
disk temperatures measured in stellar-mass Galactic black holes when observed
in their brightest states. Because disk temperature is expected to fall with
increasing black hole mass, and because the X-ray luminosity of these sources
exceeds the Eddington limit for 10 Msun black holes (L_Edd = 1.3 E+39 erg/s),
these sources are extremely promising intermediate-mass black hole candidates
(IMBHCs). In this Letter, we directly compare the inferred disk temperatures
and luminosities of these ULXs, with the disk temperatures and luminosities of
a number of Galactic black holes. The sample of stellar-mass black holes was
selected to include different orbital periods, companion types, inclinations,
and column densities. These ULXs and stellar-mass black holes occupy distinct
regions of a L_X -- kT diagram, suggesting these ULXs may harbor IMBHs. We
briefly discuss the important strengths and weaknesses of this interpretation.


title:
The Formation Rate, Mass and Luminosity Functions of DA White Dwarfs
  from the Palomar Green Survey

abstract:
  Spectrophotometric observations at high signal-to-noise ratio were obtained
of a complete sample of 347 DA white dwarfs from the Palomar Green (PG) Survey.
Fits of observed Balmer lines to synthetic spectra calculated from
pure-hydrogen model atmospheres were used to obtain robust values of Teff, log
g, masses, radii, and cooling ages. The luminosity function of the sample,
weighted by 1/Vmax, was obtained and compared with other determinations. The
mass distribution of the white dwarfs is derived, after important corrections
for the radii of the white dwarfs in this magnitude-limited survey and for the
cooling time scales. The formation rate of DA white dwarfs from the PG is
estimated to be 0.6x10^(-12) pc^(-3) yr^(-1). Comparison with predictions from
a theoretical study of the white dwarf formation rate for single stars
indicates that >80% of the high mass component requires a different origin,
presumably mergers of lower mass double degenerate stars. In order to estimate
the recent formation rate of all white dwarfs in the local Galactic disk,
corrections for incompleteness of the PG, addition of the DB-DO white dwarfs,
and allowance for stars hidden by luminous binary companions had to be applied
to enhance the rate. An overall formation rate of white dwarfs recently in the
local Galactic disk of 1.15+/-0.25x10^(-12) pc^(-3) yr^(-1) is obtained. Two
recent studies of samples of nearby Galactic planetary nebulae lead to
estimates around twice as high. Difficulties in reconciling these
determinations are discussed.


title: Calibration of cameras of the H.E.S.S. detector

abstract:
  H.E.S.S. - the High Energy Stereoscopic System- is a new system of large
atmospheric Cherenkov telescopes for GeV/TeV astronomy. Each of the four
telescopes of 107 m^2 mirror area is equipped with a 960-pixel
photomulitiplier-tube camera. This paper describes the methods used to convert
the photomultiplier signals into the quantities needed for Cherenkov image
analysis. Two independent calibration techniques have been applied in parallel
to provide an estimation of uncertainties. Results on the long-term stability
of the H.E.S.S. cameras are also presented.


title: Nucleosynthesis in Fast Expansions of High-Entropy, Proton Rich Matter

abstract:
  We demonstrate that nucleosynthesis in rapid, high-entropy expansions of
proton-rich matter from high temperature and density can result in a wider
variety of abundance patterns than heretofore appreciated. In particular, such
expansions can produce iron-group nuclides, p-process nuclei, or even heavy,
neutron-rich isotopes. Such diversity arises because the nucleosynthesis enters
a little explored regime in which the free nucleons are not in equilibrium with
the abundant alpha particles. This allows nuclei significantly heavier than
iron to form in t he presence of abundant free nucleons early in the expansion.
As the temperature drops, nucleons increasingly assemble into alpha particles
and heavier nuclei. If the assembly is efficient, the resulting depletion of
free neutrons allows disintegrat ion flows to drive nuclei back down to iron
and nickel. If this assembly is inefficient, then the large abundance of free
nucleons prevents the disintegration flows and leaves a distribution of heavy
nuclei after reaction freezeout. For cases in between, an intermediate
abundance distribution, enriched in p-process isotopes, is frozen out. These
last expansions may contribute to the solar system's supply of the p-process
nuclides if mildly proton-rich, high-entropy matter is ejected from
proto-neutron stars winds or other astrophysical sites. Also sign ificant is
the fact that, because the nucleosynthesis is primary, the signature of this
nucleosyn thesis may be evident in metal poor stars.


title: On the Gravitational Field of Antimatter

abstract:
  The gravitational field of matter and that of antimatter could differ. This
might be one signature of quantum gravity. We show that primordial Big Bang
Nucleosynthesis restricts such a possibility.


title: X-ray astronomy of stellar coronae (Review)

abstract:
  X-ray emission from stars in the cool half of the Hertzsprung-Russell diagram
is generally attributed to the presence of a magnetic corona that contains
plasma at temperatures exceeding 1 million K. Coronae are ubiquitous among
these stars, yet many fundamental mechanisms operating in their magnetic fields
still elude an interpretation through a detailed physical description. Stellar
X-ray astronomy is therefore contributing toward a deeper understanding of the
generation of magnetic fields in magnetohydrodynamic dynamos, the release of
energy in tenuous astrophysical plasmas through various plasma-physical
processes, and the interactions of high-energy radiation with the stellar
environment. Stellar X-ray emission also provides important diagnostics to
study the structure and evolution of stellar magnetic fields from the first
days of a protostellar life to the latest stages of stellar evolution among
giants and supergiants. The discipline of stellar coronal X-ray astronomy has
now reached a level of sophistication that makes tests of advanced theories in
stellar physics possible. This development is based on the rapidly advancing
instrumental possibilities that today allow us to obtain images with
sub-arcsecond resolution and spectra with resolving powers exceeding 1000.
High-resolution X-ray spectroscopy has, in fact, opened new windows into
astrophysical sources, and has played a fundamental role in coronal research.
  The present article reviews the development and current status of various
topics in the X-ray astronomy of stellar coronae, focusing on observational
results and on theoretical aspects relevant to our understanding of coronal
magnetic structure and evolution.


title:
Power Spectrum Sensitivity and the Design of Epoch of Reionization
  Observatories

abstract:
  Recent theoretical developments for observing the Epoch of Reionization (EOR)
have concentrated on the power spectrum signature of redshifted 21 cm emission.
These studies have demonstrated the great potential of statistical EOR
observations, however, the sensitivity calculations for proposed low frequency
radio arrays have been highly approximate. The formalism developed for
interferometric measurements of the cosmic microwave background can be extended
to three dimensions to naturally incorporate the line-of-sight information
inherent in the EOR signal. In this paper we demonstrate how to accurately
calculate the EOR power spectrum sensitivity of an array, and develop scaling
relationships which can be used to guide the design of EOR observatories. The
implications for antenna distribution, antenna size, and correlator
requirements on the EOR sensitivity are detailed.


title: Big Bang Nucleosynthesis (in "The Review of Particle Properties" 2004)

abstract:
  A critical review is given of the current status of cosmological
nucleosynthesis. In the framework of the standard model with 3 types of
relativistic neutrinos, the baryon-to-photon ratio, \eta, corresponding to the
inferred primordial abundances of helium-4 and lithium-7 is presently ~2 \sigma
below the value implied by the abundance of deuterium. The latter value is also
coincident with the independent determination of \eta from WMAP observations of
CMB anisotropy. However taking systematic uncertainties in the abundance
estimates into account, there is overall concordance in the range \eta = (3.4 -
6.9) x 10^{-10} @ 95% c.l. corresponding to a cosmological baryon density
\Omega_B h^2 = 0.012 - 0.025. If the above discrepancy is due to a neutrino
chemical potential, then upto 7.1 effective neutrino species are allowed by
nucleosynthesis. Other constraints on new physics are briefly discussed.


title:
The Solar Neighborhood IX: Hubble Space Telescope Detections of
  Companions to Five M and L Dwarfs within 10 pc of the Sun

abstract:
  We report the detections of low-mass companions to five M and L dwarfs within
10 pc of the Sun using the Hubble Space Telescope (HST) Near-Infrared Camera
and Multi-Object Spectrometer (NICMOS). Follow-up observations using the HST
Advanced Camera for Surveys (ACS) and Fine Guidance Sensor 1r (FGS1r) confirm
our NICMOS discoveries of companions to the L4.5 dwarf GJ 1001B (LHS 102B) and
the M5 dwarf LHS 224, respectively. Images obtained with the Astrophysical
Research Consortium 3.5 m telescope at Apache Point Observatory verify our
discovery of a companion to the M3 dwarf G 239-25. Our NICMOS images confirm
the previously suspected duplicity of the M3 dwarfs GJ 54 and GJ 84. The
components of GJ 1001BC and LHS 224AB have nearly equal luminosities in all the
ACS and/or NICMOS bandpasses in which they were observed. The magnitudes of GJ
54A and B in one FGS1r bandpass and four NICMOS bandpasses differ by <~ 1. GJ
84B and G 239-25B are ~4 magnitudes fainter than their M3 companions in the
NICMOS bandpasses. We estimate from our NICMOS photometry that GJ 84B and G
239-25B have spectral types M7 and M8, respectively, and masses near the lower
limit for sustained hydrogen burning. The apparent separations of GJ 1001BC, GJ
54AB, and LHS 224AB suggest orbital periods less than 5 yr. These binary dwarfs
are ideal candidates for continued astrometric monitoring that will quickly
yield accurate dynamic masses needed to constrain the mass-luminosity relation
for low-mass stars and brown dwarfs.


title: Inter-cluster filaments in a $\Lambda$CDM Universe

abstract:
  The large--scale structure (LSS) in the Universe comprises a complicated
filamentary network of matter. We study this network using a high--resolution
simulation of structure formation of a $\Lambda$ Cold Dark Matter cosmology. We
investigate the distribution of matter between neighbouring large haloes whose
masses are comparable to massive clusters of galaxies. We identify a total of
228 filaments between neighbouring clusters. Roughly half of the filaments are
either warped or lie off the cluster--cluster axis. We find that straight
filaments on the average are shorter than warped ones. More massive clusters
are connected to more filaments than less massive ones on average. This finding
indicates that the most massive clusters form at the intersections of the
filamentary backbone of LSS. For straight filaments, we compute mass profiles.
Radial profiles show a fairly well--defined radius, $r_s$, beyond which the
profiles follow an $r^{-2}$ power law fairly closely. For the majority of
filaments, $r_s$ lies between 1.5 $h^{-1}$ Mpc and 2.0 $h^{-1}$ Mpc. The
enclosed overdensity inside $r_s$ varies between a few times up to 25 times
mean density, independent of the length of the filaments. Along the filaments'
axes, material is not distributed uniformly. Towards the clusters, the density
rises, indicating the presence of the cluster infall regions. In addition, we
also find some sheet--like connections between clusters. In roughly a fifth of
all cluster--cluster connections where we could not identify a filament or
sheet, projection effects lead to filamentary structures in the projected mass
distribution. (abridged)


title: PANIC: A Near-infrared Camera for the Magellan Telescopes

abstract:
  PANIC (Persson's Auxiliary Nasmyth Infrared Camera) is a near-infrared camera
designed to operate at any one of the f/11 folded ports of the 6.5m Magellan
telescopes at Las Campanas Observatory, Chile. The instrument is built around a
simple, all-refractive design that reimages the Magellan focal plane to a plate
scale of 0.125'' pixel^{-1} onto a Rockwell 1024x1024 HgCdTe detector. The
design goals for PANIC included excellent image quality to sample the superb
seeing measured with the Magellan telescopes, high throughput, a relatively
short construction time, and low cost. PANIC has now been in regular operation
for over one year and has proved to be highly reliable and produce excellent
images. The best recorded image quality has been ~0.2'' FWHM.


title:
Bars from the Inside Out: An HST Study of their Dusty Circumnuclear
  Regions

abstract:
  The results of bar-driven mass inflow are directly observable in
high-resolution HST observations of their circumnuclear regions. These
observations reveal a wealth of structures dominated by dust lanes, often with
a spiral-like morphology, and recent star formation. Recent work has shown that
some of these structures are correlated with the presence or absence of a bar.
I extend this work with an investigation of circumnuclear morphology as a
function of bar strength for a sample of 48 galaxies with both measured bar
strengths and ``structure maps'' computed from HST images. The structure maps
for these galaxies, which have projected spatial resolutions of 2 - 15 pc, show
that the fraction of galaxies with grand-design (GD) circumnuclear dust spirals
increases significantly with bar strength, while tightly wound dust spirals are
only present in the most axisymmetric galaxies. GD structure is only found at
the centers of galaxies classified as SB(s) or SB(rs) and not SB(r). SB(s)
galaxies on average have stronger bars than SB(r) galaxies. There is also a
modest increase in the fraction of loosely wound dust spirals at later
morphological types, which may reflect an increase in the fraction of galaxies
with circumnuclear, gaseous disks. (abridged)


title: Jet-Induced Star Formation: Good News From Big Bad Black Holes

abstract:
  We discuss obbservations and numerical simulations which show that radiative
shocks in jet-cloud collisions can trigger the collapse of intergalactic clouds
and subsequent star formation in low luminosity, 'FR-I' type, radio galaxies.


title: Penetrating Dust Tori in AGN

abstract:
  We present preliminary results from high resolution (~ 0.05") adaptive optics
observations of Cygnus A. The images show a bi-conic structure strongly
suggestive of an obscuring torus around a quasar nucleus. A bright (K'=18.5)
point source is found near the expected position of the nucleus. We interpret
this source as the hot inner rim of the torus seen through the opening of the
torus. Using high angular resolution K-band spectroscopy, we measure the ratio
of molecular to recombination hydrogen lines as a function of distance to the
center of the putative torus. These measurements place constraints on the
properties of the torus and indicate a projected diameter of ~600 pc.


title: Inflation After WMAP

abstract:
  I examine the status of inflationary cosmology in light of the first-year
data from the WMAP satellite, focusing on the simplest models of inflation:
those driven by a single scalar field. The WMAP observation of the Cosmic
Microwave Background is the first unified, self-consistent data set capable of
putting meaningful constraints on the inflationary parameter space. WMAP
provides significant support for the inflationary paradigm in general, and
single-field slow-roll inflation models provide a good fit to existing
observational constraints.


title:
Spectroscopic Identification of Faint White Dwarf Candidates in the
  Praesepe Open Star Cluster

abstract:
  We present spectroscopic observations of the remaining four candidate white
dwarfs in Praesepe. All four candidates are quasars with redshifts between 0.8
and 2.8. One quasar, LB 6072, is observed to have a strong metal-line
absorption system blueward of the quasar redshift. The lack of additional white
dwarfs in Praesepe leaves the total known white-dwarf population of the cluster
at five, well below the number expected from commonly-assumed initial mass
functions, though several undiscovered cluster WDs may lie in the outer regions
of the cluster. All known Praesepe member white dwarfs are concentrated within
0.6 deg of the cluster center, and the radial profile of cluster white dwarfs
is quite similar to the profile of massive cluster stars. This profile is
mildly inconsistent with that of ~1Mo cluster stars and suggests that the white
dwarfs did not receive a velocity kick during the progenitor star's mass loss
phases. If complete, the observed Praesepe white dwarf population is consistent
with a steeper high-end initial-mass function than commonly assumed, though the
calculated slopes are inconsistent with the present-day mass function of
Praesepe. Searches for white dwarfs outside the core of Praesepe and further
study of the white dwarf populations of additional open clusters is necessary
to constrain further the underlying cause of the white dwarf deficit.


title:
Rejoinder to "No Evidence of Dark Energy Metamorphosis",
  astro-ph/0404468

abstract:
  In a recent paper (astro-ph/0311364) Alam et al argued that the SNe data of
Tonry et al 2003 and Barris et al 2003 appear to favour DE which evolves in
time, provided no other priors are invoked. (The effect of invoking priors such
as the age of the Universe, the values of $H_0$ and $\Omega_m$ and CMB/LSS
observations could modify this conclusion, as demonstrated in astro-ph/0403687
and other recent papers.) The approach adopted by Alam et al to reconstruct the
properties of DE was severely (and, as we shall show below -- unfairly)
criticized by J\"onsson et al in astro-ph/0404468. In this paper we re-examine
the parametrisation used in astro-ph/0311364 and show that, contrary to the
claims of J\"onsson et al, the results obtained from this reconstruction are
robust and therefore representative of the true nature of dark energy.


title:
The Standard Model, Dark Matter, and Dark Energy: From the Sublime to
  the Ridiculous

abstract:
  The Standard Model of cosmology of the 1980's was based on a remarkable
interplay of ideas from particle theory, experiment and astrophysical
observations. That model is now dead, and has been replaced by something far
more bizarre. Interestingly, the aspect that has survived involves perhaps the
most exotic component: dark matter that dominates the gravitational dynamics of
all galaxies, and appears to be composed of a sea of new weakly interacting
elementary particles. But this sea of dark matter appears to play second fiddle
to an unknown energy density that appears to permeate all of space, causing the
expansion of the Universe to accelerate. We are left with many more questions
than answers, and our vision of the future of the Universe has completely
changed. (Lectures Given at the XIV Canary Islands Winter School in
Astrophysics 2002: Dark Matter and Dark Energy in the Universe. Nov 2002 To
Appear in the Proceedings)


title: The Cooling Behavior of Thermal Pulses in Gamma-Ray Bursts

abstract:
  We discuss gamma-ray bursts that have very hard spectra, consistent with
black-body radiation, throughout their duration. We find that the temperature
decay during a pulse can be well described by a broken power-law in time, with
an initially constant or weak decay. After the break, most cases are consistent
with a decay with index -2/3. Some pulses have a weak non-thermal component
overlayed the thermal one, and are better modelled with a combination of a
thermal and a non-thermal component. Such a two-component model can explain the
whole time-evolution of other bursts, that are found to be only initially
thermal and later become non-thermal. The relative strengths between the two
components vary with time and this is suggested to, among other things, account
for the change in the modelled low-energy power-law slope that is often
observed in bursts. We interpret the observations within a model of an
optically thick shell that expands adiabatically. The slow, or constant,
temperature decrease is from the acceleration phase, during which the bulk
Lorentz factor increases, and the faster temperature decay is reached as the
flow saturates and starts to coast with a constant speed. We also discuss a
Poynting-flux model, in which the saturation radius is reached close to the
photosphere.


title:
Warm water vapor envelope in Mira variables and its effects on the
  apparent size from the near-infrared to the mid-infrared

abstract:
  We present a possible interpretation for the increase of the angular diameter
of the Mira variables o Cet, R Leo, and chi Cyg from the K band to the 11
micron region revealed by the recent interferometric observations using narrow
bandpasses where no salient spectral feature is present (Weiner et al. 2003a,
2003b). A simple two-layer model consisting of hot and cool H2O layers for the
warm water vapor envelope can reproduce the angular diameters observed with
Infrared Spatial Interferometer as well as the high-resolution TEXES spectra
obtained in the 11 micron region. The strong absorption of H2O expected from
the dense water vapor envelope is filled in by emission from the extended part
of the envelope, and this results in the high-resolution 11 micron spectra
which exhibit only weak, fine spectral features, masking the spectroscopic
evidences of the dense, warm water vapor envelope. On the other hand, the
presence of the warm water vapor envelope manifests itself as the larger
angular diameters in the 11 micron region as compared to those measured in the
near-infrared. Furthermore, comparison of the visibilities predicted in the
near-infrared with observational results available in the literature
demonstrates that our two-layer model for the warm water vapor envelope can
also reproduce the observed near-infrared visibilities and angular diameters.
The radii of the hot H2O layers in the three Mira variables are derived to be
1.5--1.7 Rstar with temperatures of 1800--2000 K and H2O column densities of
(1--5) x 10^{21} cm^{-2}, while the radii of the cool H2O layers are derived to
be 2.2--2.5 Rstar with temperatures of 1200--1400 K and H2O column densities of
(1--7) x 10^{21} cm^{-2}.


title:
On using visibility correlations to probe the HI distribution from the
  dark ages to the present epoch I: Formalism and the expected signal

abstract:
  Redshifted 21 cm radiation originating from the cosmological distribution of
neutral hydrogen (HI) appears as a background radiation in low frequency radio
observations. The angular and frequency domain fluctuations in this radiation
carry information about cosmological structure formation. We propose that
correlations between visibilities measured at different baselines and
frequencies in radio-interferometric observations be used to quantify the
statistical properties of these fluctuations. This has an inherent advantage
over other statistical estimators in that it deals directly with the
visibilities which are the primary quantities measured in radio-interferometric
observations. Also, the visibility correlation has a very simple relation with
power spectrum. We present estimates of the expected signal for nearly the
entire post-recombination era, from the dark ages to the present epoch. The
epoch of reionization, where the HI has a patchy distribution, has a distinct
signature where the signal is determined by the size of the discrete ionized
regions. The signal at other epochs, where the HI follows the dark matter, is
determined largely by the power spectrum of dark matter fluctuations. The
signal is strongest for baselines where the antenna separations are within a
few hundred times the wavelength of observation, and an optimal strategy would
preferentially sample these baselines. In the frequency domain, for most
baselines the visibilities at two different frequencies are uncorrelated beyond
\Delta \nu ~ 1 MHz, a signature which in principle would allow the HI signal to
be easily distinguished from the continuum sources of contamination.


title: On the Survival of Short-Period Terrestrial Planets

abstract:
  The currently feasible method of detection of Earth-mass planets is transit
photometry, with detection probability decreasing with a planet's distance from
the star. The existence or otherwise of short-period terrestrial planets will
tell us much about the planet formation process, and such planets are likely to
be detected first if they exist. Tidal forces are intense for short-period
planets, and result in decay of the orbit on a timescale which depends on
properties of the star as long as the orbit is circular. However, if an
eccentric companion planet exists, orbital eccentricity ($e_i$) is induced and
the decay timescale depends on properties of the short-period planet, reducing
by a factor of order $10^5 e_i^2$ if it is terrestrial. Here we examine the
influence companion planets have on the tidal and dynamical evolution of
short-period planets with terrestrial structure, and show that the relativistic
potential of the star is fundamental to their survival.


title: Synthesizing Deuterium in Incipient Pop II Stars

abstract:
  Sites for incipient low metallicity (Pop II) star formation can support
environments conducive to Deuterium production up to levels observed in the
universe. This could have a deep impact on a ``Standard Cosmology''.


title:
Metal abundances in extremely distant Galactic old open clusters. I.
  Berkeley 29 and Saurer 1

abstract:
  We report on high resolution spectroscopy of four giant stars in the Galactic
old open clusters Berkeley~29 and Saurer~1 obtained with HIRES at the Keck
telescope. These two clusters possess the largest galactocentric distances
insofar known for open star clusters, and therefore are crucial objects to
probe the chemical pattern and evolution of the outskirts of the Galactic disk.
We find that $[Fe/H]=-0.38\pm0.14$ and $[Fe/H]=-0.44\pm0.18$ for Saurer 1 and
Berkeley~29, respectively. Based on these data, we first revise the fundamental
parameters of the clusters, and then discuss them in the context of the
Galactic disk radial abundance gradients. Both clusters seem to significantly
deviate from the general trend, suggesting that the outer part of the Galactic
disk underwent a completely different evolution compared to the inner disk. In
particular Berkeley~29 is clearly associated with the Monoceros stream, while
Saurer~1 exhibits very different properties. The abundance ratios suggest that
the chemical evolution of the outer disk was dominated by the Galactic halo.


title:
The G9.62+0.19-F Hot Molecular Core - The infrared view on very young
  massive stars

abstract:
  (abridged) We present the results of an extensive infrared study of the
massive star-forming region G9.62+0.19. The data cover information from broad-
and narrow-band filters in the wavelength range from 1 to 19 micrometer and are
obtained with ESO's infrared cameras ISAAC and TIMMI2 and with SpectroCam-10
(Mt. Palomar). The high sensitivity and resolution provided by these facilities
revealed intriguing new details of this star-forming region and especially
about the embedded hot molecular core (HMC) - component F. We analyse the newly
found infrared sub-structure of four objects in this HMC region. While one of
these objects (F2) is probably a foreground field star, the nature of the
brightest object in the near-infrared there (F1) remains somewhat enigmatic.
Our new astrometry proves that this object is not coincident with the peak of
the molecular line emission of the HMC, but displaced by 1.7 arcsecs (nearly
10000 AU on a linear scale). We estimate this object to be an additional
embedded object with a dense dust shell. Very near the HMC location we find L'
band emission which strongly rises in flux towards longer wavelengths. We
presume that this emission (F4) arises from the envelope of the HMC which is
known to be associated with a molecular outflow roughly aligned along the line
of sight. Thus, the clearing effect of this outflow causes strong deviations
from spherical symmetry which might allow infrared emission from the HMC to
escape through the outflow cavities. This presents the first direct detection
of an HMC at a wavelength as short as 3.8 micron. At 11.7 and 18.75 micron, the
HMC counterpart F4 ultimately proves to be the most luminous IR source within
the G9.62+0.19-F region.


title: The Cosmological Parameters

abstract:
  This is a new review article for The Review of Particle Physics 2004 (aka the
Particle Data Book). It forms a compact review of knowledge of the cosmological
parameters as at the end of 2003. Topics included are Parametrizing the
Universe; Extensions to the standard model; Probes; Bringing observations
together; Outlook for the future.


title: Improved mosaicking capabilities with JEM-X

abstract:
  Observations performed by INTEGRAL are typically subdivided in kilo-seconds
individual pointings. A mosaic software has been developed at the Danish Space
Research Institute to combine sky images from different pointings with
significantly improved capabilities compared to the available software. This
software takes account of the specifics of the JEM-X instrument, such as the
vignetting effects due to its collimator and its mask structure. It calculates
the weighted contribution of each pixel from each input sky images to be added
in order to maximise the signal/noise ratio of each pixel in the combined sky
image. The software produces mosaic'ed maps with the source signal and of the
noise in each pixel, and is used as a tool to find new X-rays sources that are
too weak to be seen in individual pointings.


title: GX 301-2 as seen by Integral

abstract:
  We present observations of the High Mass X-ray Binary GX 301-2 taken during
the Galactic Plane Scan (GPS) with Integral following our RXTE observations
(Kreykenbohm et al. 2004). The optical companion of GX 301-2 is the B1Ia+
hypergiant Wray 977 with a luminosity of 1.3 x 10^6 Lsun and a mass of ~48 Msun
making the system one of the most massive X-ray binaries known. The system was
observed 24 times during the GPS thus covering many orbital phases including
the pre-periastron flare. The source is clearly detected in all Integral
instruments in most pointings. The derived X-ray light curves show strong
variability on all timescales. Depending on the orbital phase of the pointings,
the luminosity changes by factor of more than 10 during the pre-periastron
flare compared to other pointings. Furthermore, broad band spectra using all
instruments available on Integral are compared with data taken by the RXTE
instruments PCA and HEXTE (using the same data as in Kreykenbohm et al. 2004).


title:
Cosmic-Ray Background Flux Model based on a Gamma-Ray Large-Area Space
  Telescope Balloon Flight Engineering Model

abstract:
  Cosmic-ray background fluxes were modeled based on existing measurements and
theories and are presented here. The model, originally developed for the
Gamma-ray Large Area Space Telescope (GLAST) Balloon Experiment, covers the
entire solid angle (${\rm 4\pi sr}$), the sensitive energy range of the
instrument (${\rm \sim 10 MeV to 100 GeV}$) and abundant components (proton,
alpha, $e^{-}$, $e^{+}$, $\mu^{-}$, $\mu^{+}$ and gamma). It is expressed in
analytic functions in which modulations due to the solar activity and the Earth
geomagnetism are parameterized. Although the model is intended to be used
primarily for the GLAST Balloon Experiment, model functions in low-Earth orbit
are also presented and can be used for other high energy astrophysical
missions. The model has been validated via comparison with the data of the
GLAST Balloon Experiment.


title:
Optically Thick Clumps - Not the Solution to the Wolf-Rayet Wind
  Momentum Problem?

abstract:
  The hot star wind momentum problem \eta = mdot*vinfty/(L/c) >> 1 is
revisited, and it is shown that the conventional belief, that it can be solved
by a combination of clumping of the wind and multiple scattering of photons, is
not self-consistent for optically thick clumps. Clumping does reduce the mass
loss rate mdot, and hence the momentum supply, required to generate a specified
radio emission measure \varepsilon, while multiple scattering increases the
delivery of momentum from a specified stellar luminosity L. However, in the
case of thick clumps, when combined the two effects act in opposition rather
than in unison since clumping reduces multiple scattering. Thus the ratio of
momentum deliverable to momentum required is maximal for a smooth wind and the
momentum problem remains for the thick clump case. In the case of thin clumps,
all of the benefit of clumping in reducing \eta lies in reducing \mdot for a
given \varepsilon so that extremely small filling factors f = 10e-4 are needed.
It is also shown that clumping affects the inference of \mdot from radio
\varepsilon not only by changing the emission measure per unit mass but also by
changing the radio optical depth unity radius R_{rad}, and hence the observed
wind volume, at radio wavelengths.


title:
A Principal Components Analysis of the Lick Indices of Galactic Globular
  Clusters

abstract:
  We present a principal components analysis (PCA) of high-quality Lick/IDS
absorption-line measurements for 11 indices in the wavelength range 4100-5400
Ang for 39 Galactic globular clusters (GCs). Only the first principal component
appears to be physically significant. We find that there is a tight linear
relationship between this first component (PC1) and GC metallicity over a wide
range in [m/H] (-1.8 <= [m/H] <= 0), suggesting that PC1 may be used to
accurately estimate metallicities for old extragalactic GCs from their
integrated spectra. The classic GC ``second parameter effect'' is noticeable in
the Balmer indices, though it does not appear in our PCA. We find little
evidence for substantial differences in broad abundance patterns among Galactic
GCs. One implication is that the metal-poor and metal-rich GC subpopulations
formed from very similar physical processes.


title: The Dynamics of Two Massive Planets on Inclined Orbits

abstract:
  The significant orbital eccentricities of most giant extrasolar planets may
have their origin in the gravitational dynamics of initially unstable multiple
planet systems. In this work, we explore the dynamics of two close planets on
inclined orbits through both analytical techniques and extensive numerical
scattering experiments. We derive a criterion for two equal mass planets on
circular inclined orbits to achieve Hill stability, and conclude that
significant radial migration and eccentricity pumping of both planets occurs
predominantly by 2:1 and 5:3 mean motion resonant interactions. Using
Laplace-Lagrange secular theory, we obtain analytical secular solutions for the
orbital inclinations and longitudes of ascending nodes, and use those solutions
to distinguish between the secular and resonant dynamics which arise in
numerical simulations. We also illustrate how encounter maps, typically used to
trace the motion of massless particles, may be modified to reproduce the gross
instability seen by the numerical integrations. Such a correlation suggests
promising future use of such maps to model the dynamics of more coplanar
massive planet systems.


title: The abundance of 36S in IRC+10216 and its production in the Galaxy

abstract:
  The J=2-1 and 3-2 rotational lines of the rare isotopomer C36S and the J=5-4
and 6-5 transitions of Si36S were detected in the carbon star IRC+10216 (CW
Leo). These are the first detections of 36S bearing molecules in a star and the
first spectroscopic detection of Si36S. From a comparison of 34S and 36S
bearing isotopomers, th 34S/36S isotopic ratio is 107(+-15). This value is
comparable to values in the interstellar medium of the inner Galactic disk
(115) but is smaller than the solar value of 288 (Ding et al. 2001). The
increase of the 36S abundance relative to 34S only qualitatively follows model
predictions of a low mass AGB star. Quantitative agreement of the observed
34S/36S ratio with the stellar models can be reached if the age of IRC+10216
and Galactic chemical evolution are taken into account. Other less likely
possibilities are the presence of considerable inhomogeneities in the
interstellar medium and either IRC+10216 or the Sun started with a peculiar 36S
abundance. Other production mechanisms potentially capable of enhancing the
Galactic interstellar medium are discussed. From the observed line density
toward IRC+10216 and toward Galactic star forming regions, we estimate the
confusion limit toward those sources.


title: Photodissociation and the Morphology of HI in Galaxies

abstract:
  Young massive stars produce Far-UV photons which dissociate the molecular gas
on the surfaces of their parent molecular clouds. Of the many dissociation
products which result from this ``back-reaction'', atomic hydrogen \HI is one
of the easiest to observe through its radio 21-cm hyperfine line emission. In
this paper I first review the physics of this process and describe a simplified
model which has been developed to permit an approximate computation of the
column density of photodissociated \HI which appears on the surfaces of
molecular clouds. I then review several features of the \HI morphology of
galaxies on a variety of length scales and describe how photodissociation might
account for some of these observations. Finally, I discuss several consequences
which follow if this view of the origin of HI in galaxies continues to be
successful.


title:
Galactic Center Extinction: Evidence for Metallic Needles in the General
  Interstellar Medium

abstract:
  The extinction curve derived from ISO mid-infrared (IR) observations of the
Galactic center (GC) exhibits a surprisingly flat behavior in the ~ 3 to 8
micron region, contrary to the deep minimum expected from standard interstellar
dust models consisting of bare silicate and graphite dust particles. We show
that this extinction is likely caused by the presence of metallic needles in
the interstellar medium (ISM) towards the Galactic center. If the needles
contribute only to the 3 - 8 micron extinction, they must have a long
wavelength cutoff at ~ 8 microns, and therefore a typical length over radius
ratio of about 600, smaller than the 3000 aspect ratio determined for the
needles in Cas A. Homogeneously distributed throughout the ISM, they comprise
only a minor mass fraction of the ISM, with a needle-to-H mass ratio of
\~5x10^{-6}, which is equivalent to 0.14% of the silicate dust mass. Their
total ISM abundance can then be readily explained by the combined production in
SNe and O-rich stellar outflows. It is currently unclear how universal the GC
extinction law is. Local 2 - 5 micron extinction measurements seem to be
consistent with the standard extinction law, suggesting a non uniform
distribution of needles in the ISM. The GC observations show that metallic
needles, in spite of their low abundance or non uniform distribution, can be
the dominant source of opacity in the 3 - 8 micron wavelength region. However,
expelled into the intergalactic medium, their abundance is too low to cause any
dimming of cosmological sources, and their length is too short to make them a
significant source of submillimeter emission.


title:
The Magellanic Clouds Photometric Survey: The Large Magellanic Cloud
  Stellar Catalog and Extinction Map

abstract:
  We present our catalog of U, B, V, and I stellar photometry of the central 64
sq. deg. area of the Large Magellanic Cloud. Internal and external astrometric
and photometric tests using existing optical photometry (U, B, and V from
Massey's bright star catalog and I from the near-infrared sky survey DENIS) are
used to confirm our observational uncertainty estimates. We fit stellar
atmosphere models to the optical data to check the consistency of the
photometry for individual stars across the passbands and to estimate the
line-of-sight extinction. Finally, we use the estimated line-of-sight
extinctions to produce an extinction map across the Large Magellanic Cloud,
confirm the variation of extinction as a function of stellar population, and
produce a simple geometrical model for the extinction as a function of stellar
population.


title:
Spatially Resolved Ultraviolet Spectra of the High-Velocity Nuclear
  Outflow of NGC 1068

abstract:
  We present ultraviolet emission-line maps of the narrow-line region (NLR) of
NGC 1068. The maps span 115--318 nm, the biconical ionization cone, several
posited jet/ISM interactions, and the compact knots whose optical spectra we
reported previously resemble kinematically the quasar Associated Absorption
Line systems. Across the NLR, we find that ultraviolet flux ratios are
consistent with photoionization, not shock excitation, even for gas blueshifted
abruptly to 3000 \kms relative to galaxy systemic velocity or for gas projected
near the radio jet. The knots may be radiatively accelerated, photoablated
fragments of molecular clouds.


title:
Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies: I.
  The role of ISM pressure & the Molecular Cloud Dissipation Timescale

abstract:
  In this paper, we combine the stellar spectral synthesis code STARBURST 99,
the nebular modelling code MAPPINGS IIIq, a 1-D dynamical evolution model of
\HII regions around massive clusters of young stars and a simplified model of
synchrotron emissivity to produce purely theoretical self-consistent synthetic
spectral energy distributions (SEDs) for (solar metallicity) starbursts lasting
some $10^8$ years. These SEDs extend from the Lyman Limit to beyond 21 cm. We
find that two ISM parameters control the form of the SED; the pressure in the
diffuse phase of the ISM (or, equivalently, its density), and the molecular
cloud dissipation timescale. We present detailed SED fits to Arp 220 and NGC
6240, and we give the predicted colors for starburst galaxies derived from our
models for the IRAS and the Spitzer Space Observatory MIPS and IRAC
instruments. Our models reproduce the spread in observed colors of starburst
galaxies. Finally, we present absolute calibrations to convert observed fluxes
into star formation rates in the UV (GALEX), at optical wavelengths
(H$\alpha$), and in the IR (IRAS or the Spitzer Space Observatory). (Abstract
Truncated)


title: A Cluster of 1.3 cm Continuum Sources in OMC1 South

abstract:
  We present sensitive 1.3 cm radio continuum observations of the region OMC1
South (OMC-1S) in Orion using the Very Large Array in its B configuration. We
detect eleven radio sources clustered in a $30{''} \times 30{''}$ region, of
which only three had been detected previously at radio wavelengths in deep 3.6
cm observations. The eight new radio sources are compact ($\theta_s \leq
0\rlap.{''}1$) and we set lower limits to their spectral indices, $\alpha > 0.8
\pm 0.3$ (with $S_\nu \propto \nu^{\alpha}$), that suggest that they may be
optically-thick H II regions. However, one of the new sources exhibits
significant circular polarization, indicating that gyrosynchrotron emission
with large positive spectral indices may be an alternative explanation.
Furthermore, we find that four other sources are associated with infrared
sources of low bolometric luminosity that cannot drive an H II region. Finally,
two of the sources previously detected at 3.6-cm are angularly resolved in the
1.3 cm image and their major axes have position angles that align well with
large scale outflows emanating from OMC-1S. The radio source 143-353 has a
major axis with a position angle consistent with those of the HH 202 and HH 528
flows, while the radio source 134-411 has a major axis with a position angle
consistent with that of the low-velocity molecular outflow associated with the
far-infrared source FIR~4.


title: New candidate GHz Peaked Spectrum and Compact Steep Spectrum Sources

abstract:
  Data from a recent Australia Telescope Compact Array (ATCA) program of
multi-frequency, multi-epoch monitoring of 202 active galactic nuclei with
declinations < +10 degrees have been searched for GHz Peaked Spectrum (GPS) and
Compact Steep Spectrum (CSS) radio sources. Supplementary data at higher and
lower frequencies, where available, have been used to further examine the
spectral properties of previously reported and new candidate GPS and CSS
sources. The ATCA monitoring program has allowed the variability and
polarization properties of sources previously reported as GPS and CSS sources,
and the majority of new GPS and CSS candidates, to be investigated, confirming
that these are useful diagnostics in discriminating genuine GPS and CSS sources
from variable sources that display similar spectra only temporarily. GPS
sources are confirmed to be generally more compact, and less polarized, than
CSS sources, although CSS sources show evidence for being somewhat less
variable than GPS sources at 1.4 and 2.5GHz. In addition, the widths of GPS
spectra are examined, and a significant difference is found in the GPS sample
of Snellen et al. (2000) between sources with compact double (CD) or compact
symmetric object (CSO) morphologies and sources with other morphologies, in
that CD and CSO sources have generally narrower spectra. Possible reasons for
this difference are considered.


title: Limits on a Dynamically Varying Fine Structure Constant

abstract:
  We show that using the modified form of the Dirac Hamiltonian as suggested by
Bekenstein, does not affect the analysis in [1-4] of QSO data pertaining to a
measurement of alpha variation. We obtain the present time limit on
Bekenstein's parameter, tan^{2}chi =(0.2 \pm 0.7)\times10^{-6}, from the
measurement of the hydrogen 2p fine structure using value of alpha obtained
from different experiments.


title: A Possible Origin of Bimodal Distribution of Gamma-Ray Bursts

abstract:
  We study the distribution of the durations of gamma-ray bursts (GRBs) in the
unified model of short and long GRBs recently proposed by Yamazaki, Ioka, and
Nakamura. Monte Carlo simulations show clear bimodal distributions, with
lognormal-like shapes for both short and long GRBs, in a power-law as well as a
Gaussian angular distribution of the subjets. We find that the bimodality comes
from the existence of the discrete emission regions (subjets or patchy shells)
in the GRB jet. To explain other temporal properties of short and long GRBs,
the subjet parameters should depend on the angle in the whole jet.


title:
Quantum cosmological effects from the high redshift supernova
  observations

abstract:
  Subject of this contribution is to demonstrate that the observed faintness of
the supernovae at the high redshift can be considered as a manifestation of
quantum effects at cosmological scales. We show that observed redshift
distribution of coordinate distances to the type Ia supernovae can be explained
by the local manifestations of quantum fluctuations of the cosmological scale
factor about its average value. These fluctuations can arise in the early
universe, grow with time, and produce observed accelerating or decelerating
expansions of space subdomains containing separate supernovae with high
redshift whereas the universe as a whole expands at a steady rate.


title:
Oxygen and nitrogen abundances in nearby galaxies. Correlations between
  oxygen abundance and macroscopic properties

abstract:
  We performed a compilation of more than 1000 published spectra of HII regions
in spiral galaxies. The oxygen and nitrogen abundances in each HII region were
recomputed in a homogeneous way, using the P-method. The radial distributions
of oxygen and nitrogen abundances were derived. The correlations between oxygen
abundance and macroscopic properties are examined. There is a significant
difference between the L-Z relationship obtained here and that based on the
oxygen abundances determined through the R_23-calibrations. The oxygen
abundance of NGC 5457 recently determined using direct measurements of Te
(Kennicutt, Bresolin & Garnett 2003) agrees with the L-Z relationship derived
here, but is in conflict with the L-Z relationship derived with the R_23-based
oxygen abundances. The obtained L-Z relation for spirals is compared to that
for irregulars. Our sample of galaxies shows evidence that the slope of the
O/H-M_B relationship for spirals is slightly more shallow than that for
irregulars. The effective oxygen yields were estimated for spiral and irregular
galaxies. The effective oxygen yield increases with increasing luminosity from
M_B=-11 to M_B=-18 (or with increasing rotation velocity from Vrot=10 km/s to
Vrot=100 km/s) and then remains approximately constant. Irregular galaxies from
our sample have effective oxygen yields lowered by a factor of 3 at maximum,
i.e. irregular galaxies usually keep at least 1/3 of the oxygen they
manufactured during their evolution.


title: Empirical modeling of the stellar spectrum of galaxies

abstract:
  An empirical method of modeling the stellar spectrum of galaxies is proposed,
based on two successive applications of Principal Component Analysis (PCA). PCA
is first applied to the newly available stellar library STELIB, supplemented by
the J, H and K$_{s}$ magnitudes taken mainly from the 2 Micron All Sky Survey
(2MASS). Next the resultant eigen-spectra are used to fit the observed spectra
of a sample of 1016 galaxies selected from the Sloan Digital Sky Survey Data
Release One (SDSS DR1). PCA is again applied, to the fitted spectra to
construct the eigen-spectra of galaxies with zero velocity dispersion. The
first 9 galactic eigen-spectra so obtained are then used to model the stellar
spectrum of the galaxies in SDSS DR1, and synchronously to estimate the stellar
velocity dispersion, the spectral type, the near-infrared SED, and the average
reddening. Extensive tests show that the spectra of different type galaxies can
be modeled quite accurately using these eigen-spectra. The method can yield
stellar velocity dispersion with accuracies better than 10%, for the spectra of
typical S/N ratios in SDSS DR1.


title: gamma-ray emission from microquasars: a numerical model for LSI+61 303

abstract:
  We explore the possible association between the microquasar LSI+61 303 and
the EGRET source 2CG 135+01/3EG J0241$+$6103 by studying, with a detailed
numerical model, whether this system can produce the emission and the
variability detected by EGRET ($>$100 MeV) through inverse Compton (IC)
scattering. Our numerical approach considers a population of relativistic
electrons entrained in a cylindrical inhomogeneous jet, interacting with both
the radiation and the magnetic fields, taking into account the Thomson and
Klein-Nishina regimes of interaction. Our results reproduce the observed
spectral characteristics and variability at $\gamma$-rays, thus strengthening
the identification of LSI+61 303 as a high-energy $\gamma$-ray source.


title:
Studies of orbital parameters and pulse profile of the accreting
  millisecond pulsar XTE J1807-294

abstract:
  The accreting millisecond pulsar XTE J1807-294 was observed by XMM-Newton on
March 22, 2003 after its discovery on February 21, 2003 by RXTE. The source was
detected in its bright phase with an observed average count rate of 33.3 cts/s
in the EPIC-pn camera in the 0.5-10 keV energy band (3.7 mCrab). Using the
earlier established best-fit orbital period of 40.0741+/-0.0005 minutes from
RXTE observations and considering a circular binary orbit as first
approximation, we derived a value of 4.8+/-0.1 lt-ms for the projected orbital
radius of the binary system and an epoch of the orbital phase of MJD
52720.67415(16). The barycentric mean spin period of the pulsar was derived as
5.2459427+/-0.0000004 ms. The pulsar's spin-pulse profile showed a prominent
(1.5 ms FWHM) pulse, with energy and orbital phase dependence in the amplitude
and shape. The measured pulsed fraction in four energy bands was found to be
3.1+/-0.2 % (0.5-3.0 keV), 5.4+/-0.4 % (3.0-6.0 keV), 5.1+/-0.7 % (6.0-10.0
keV) and 3.7+/-0.2 % (0.5-10.0 keV), respectively. Studies of spin-profiles
with orbital phase and energy showed significant increase in its pulsed
fraction during the second observed orbit of the neutron star, gradually
declining in the subsequent two orbits, which was associated with sudden but
marginal increase in mass accretion. From our investigations of orbital
parameters and estimation of other properties of this compact binary system, we
conclude that XTE J1807-294 is very likely a candidate for a millisecond radio
pulsar.


title: Discovery of a new INTEGRAL source: IGR J19140+0951

abstract:
  IGR J19140+0951 (formerly known as IGR J19140+098) was discovered with the
INTEGRAL satellite in March 2003. We report the details of the discovery, using
an improved position for the analysis. We have performed a simultaneous study
of the 5-100 keV JEM-X and ISGRI spectra from which we can distinguish two
different states. From the results of our analysis we propose that IGR
J19140+0951 is a persistent Galactic X-ray binary, probably hosting a neutron
star although a black hole cannot be completely ruled out.


title:
DENIS detections of highly obscured galaxies in the area around
  PKS1343-601

abstract:
  We present results of a search for galaxies around the highly obscured giant
radio galaxy PKS1343-601 using the near-infrared DENIS survey. We compare our
findings with surveys in the B-band, at the 21cm line emission, and with 2MASS.
Recession velocities of galaxies in this area suggest a low-velocity-dispersion
group or cluster of galaxies including an X-ray confirmed Seyfert 2. The
colours of the galaxies have been used to examine the extinctions in this
low-latitude area where IRAS/DIRBE estimates are unreliable. We find the true
extinction to be roughly 15% lower than the IRAS/DIRBE extinctions.


title: Principal Component Analysis of RR Lyrae light curves

abstract:
  In this paper, we analyze the structure of RRab star light curves using
Principal Component Analysis. We find this is a very efficient way to describe
many aspects of RRab light curve structure: in many cases, a Principal
Component fit with 9 parameters can describe a RRab light curve including bumps
whereas a 17 parameter Fourier fit is needed. As a consequence we show
statistically why the amplitude is also a good summary of the structure of a RR
Lyrae light curve. We also use our analysis to derive an empirical relation
relating absolute magnitude to light curve structure. In comparing this formula
to those derived from exactly the same dataset but using Fourier parameters, we
find that the Principal Component Analysis approach has disticnt advantages.
These advantages are, firstly, that the errors on the coefficients in such
formulae are smaller, and secondly, that the correlation between Principal
Components is significantly smaller than the correlation between Fourier
amplitudes. These two factors lead to reduced formal errors, in some cases
estimated to be a factor of 2, on the eventual fitted value of the absolute
magnitude. This technique will prove very useful in the analysis of data from
existing large scale survey projects concerning variable stars.