title:
A Tight Upper Limit on Oscillations in the Ap star Epsilon Ursae Majoris
  from WIRE Photometry

abstract:
  Observations of Epsilon UMa obtained with the star tracker on the Wide Field
Infrared Explorer (WIRE) satellite during a month in mid-2000 are analyzed.
This is one of the most precise photometry of an Ap star. The amplitude
spectrum is used to set an upper limit of 75 parts per million for the
amplitude of stellar pulsations in this star unless it accidentally oscillates
with a single mode at the satellite orbit, its harmonics or their one day
aliases. This is the tightest limit put on the amplitude of oscillations in an
Ap star. As the rotation period of Epsilon UMa is relatively short (5.1 d), it
cannot be argued that the observations were made at a wrong rotational phase.
Our results thus support the idea that some Ap stars do not pulsate at all.


title: Detection of Sagittarius A* at 330 MHz with the Very Large Array

abstract:
  We report the detection of Sagittarius A*, the radio source associated with
our Galaxy's central massive black hole, at 330 MHz with the Very Large Array.
Implications for the spectrum and emission processes of Sagittarius A* are
discussed and several hypothetical geometries of the central region are
considered.


title: Early Disk Evolution

abstract:
  A variety of processes play a role in the evolution of protostellar disks.
Here I focus on the uncertain issue of magnetic field-disk coupling and its
implications for magnetically-driven turbulence and disk-driven winds. At
present it is clear that the magnetic field plays a crucial role in disk
evolution, but detailed conclusions cannot be drawn because the complicated
interplay between dynamics and the evolution of the grain population remains to
be explored.


title: On the physical origin of dark matter density profiles

abstract:
  The radial mass distribution of dark matter haloes is investigated within the
framework of the spherical infall model. We present a new formulation of
spherical collapse including non-radial motions, and compare the analytical
profiles with a set of high-resolution N-body simulations ranging from galactic
to cluster scales. We argue that the dark matter density profile is entirely
determined by the initial conditions, which are described by only two
parameters: the height of the primordial peak and the smoothing scale. These
are physically meaningful quantities in our model, related to the mass and
formation time of the halo. Angular momentum is dominated by velocity
dispersion, and it is responsible for the shape of the density profile near the
centre. The phase-space density of our simulated haloes is well described by a
power-law profile, rho/sigma^3 = 10^{1.46\pm0.04} (rho_c/Vvir^3)
(r/Rvir)^{-1.90\pm0.05}. Setting the eccentricity of particle orbits according
to the numerical results, our model is able to reproduce the mass distribution
of individual haloes.


title: A Slow Merger History of Field Galaxies Since z~1

abstract:
  Using deep infrared observations conducted with the CISCO imager on the
Subaru Telescope, we investigate the field-corrected pair fraction and the
implied merger rate of galaxies in redshift survey fields with Hubble Space
Telescope imaging. In the redshift interval, 0.5 < z < 1.5, the fraction of
infrared-selected pairs increases only modestly with redshift to 7% +- 6% at
z~1. This is nearly a factor of three less than the fraction, 22% +- 8%,
determined using the same technique on HST optical images and as measured in a
previous similar study. Tests support the hypothesis that optical pair
fractions at z~1 are inflated by bright star-forming regions that are unlikely
to be representative of the underlying mass distribution. By determining
stellar masses for the companions, we estimate the mass accretion rate
associated with merging galaxies. At z~1, we estimate this to be 2x10^{9 +-
0.2} solar masses per galaxy per Gyr. Although uncertainties remain, our
results suggest that the growth of galaxies via the accretion of pre-existing
fragments remains as significant a phenomenon in the redshift range studied as
that estimated from ongoing star formation in independent surveys.


title:
A New Look at the Kinematics of Neutral Hydrogen in the Small Magellanic
  Cloud

abstract:
  We have used the latest HI observations of the Small Magellanic Cloud (SMC),
obtained with the Australia Telescope Compact Array and the Parkes telescope,
to re-examine the kinematics of this dwarf, irregular galaxy. A large velocity
gradient is found in the HI velocity field with a significant symmetry in
iso-velocity contours, suggestive of a differential rotation. A comparison of
HI data with the predictions from tidal models for the SMC evolution suggests
that the central region of the SMC corresponds to the central, disk- or
bar-like, component left from the rotationally supported SMC disk prior to its
last two encounters with the Large Magellanic Cloud. In this scenario, the
velocity gradient is expected as a left-over from the original, pre-encounter,
angular momentum. We have derived the HI rotation curve and the mass model for
the SMC. This rotation curve rapidly rises to about 60 km/s up to the turnover
radius of ~3 kpc. A stellar mass-to-light ratio of about unity is required to
match the observed rotation curve, suggesting that a dark matter halo is not
needed to explain the dynamics of the SMC. A set of derived kinematic
parameters agrees well with the assumptions used in tidal theoretical models
that led to a good reproduction of observational properties of the Magellanic
System. The dynamical mass of the SMC, derived from the rotation curve, is
2.4x10^9 Msolar.


title: Magnetic Acceleration and Collimation of Gamma-Ray Burst Jets

abstract:
  Exact semianalytic solutions for GRB outflows were recently derived using the
equations of special-relativistic ideal MHD (see Vlahakis & Konigl in these
Proceedings for a summary). This contribution focuses on the implications of
these results to various modeling and observational issues in GRB sources,
including the baryon loading problem, polarization measurements of the prompt
and reverse-shock emission, and the possible existence of a two-component
outflow.


title:
Large-scale magnetic fields in GRB outflows: acceleration, collimation,
  and neutron decoupling

abstract:
  Using ideal magnetohydrodynamics we examine an outflow from a disk
surrounding a stellar-mass compact object. We demonstrate that the magnetic
acceleration is efficient (of the order of 50% or more of the magnetic energy
can be transformed into kinetic energy of baryons with Lorentz factors above
100) and also that the jet becomes collimated to very small opening angles.
Observational implications, focusing on the case of an initially neutron-rich
outflow, are discussed in Konigl's contribution to these Proceedings.


title: The Evolution of Diffuse Radio Sources in Galaxy Clusters

abstract:
  We investigate the evolution and number distribution of radio halos in galaxy
clusters. Without re-acceleration or regeneration, the relativistic electrons
responsible for the diffuse radio emission will lose their energy via
inverse-Compton and synchrotron losses in a rather short time, and radio halos
will have lifetimes $\sim$ 0.1 Gyr. Radio halos could last for $\sim$ Gyr if a
significant level of re-acceleration is involved. The lifetimes of radio halos
would be comparable with the cosmological time if the radio-emitting electrons
are mainly the secondary electrons generated by pion decay following
proton-proton collisions between cosmic-ray protons and the thermal
intra-cluster medium within the galaxy clusters. Adopting both observational
and theoretical constraints for the formation of radio halos, we calculate the
formation rates and the comoving number density of radio halos in the
hierarchical clustering scheme. Comparing with observations, we find that the
lifetimes of radio halos are $\sim$ Gyr. Our results indicate that a
significant level of re-acceleration is necessary for the observed radio halos
and the secondary electrons may not be a dominant origin for radio halos.


title: Characteristic Angular Scales in Cosmic Microwave Background Radiation

abstract:
  We investigate the stochasticity in temperature fluctuations in the cosmic
microwave background (CMB) radiation data from {\it Wilkinson Microwave
Anisotropy Probe}. We show that the angular fluctuations of the temperature is
a Markov process with a {\it Markov angular scale}, $\Theta_{\rm
Markov}=1.01^{+0.09}_{-0.07}$. We characterize the complexity of the CMB
fluctuations by means of a Fokker-Planck or Langevin equation and measure the
associated Kramers-Moyal coefficients for the fluctuating temperature field
$T(\hat n)$ and its increment, $\Delta T =T(\hat n_1) - T(\hat n_2)$. Through
this method we show that temperature fluctuations in the CMB has fat tails
compared to a Gaussian distribution.

categories: astro-ph cond-mat.stat-mech gr-qc hep-th physics.data-an


title: Subaru Surveys for High-z Galaxies

abstract:
  We present a summary of optical/NIR deep surveys for very high-$z$ galaxies
using the 8.2m Subaru Telescope operated by National Astronomical Observatory
of Japan. The prime focus mosaic CCD camera, Suprime-Cam, with a very wide
field of view, 34$^\prime \times 27^\prime$, allows us to carry out efficient
optical deep surveys. In particular, the Subaru Deep Field project has provided
us a number of Lyman$\alpha$ emitters beyond $z=6$. We discuss the star
formation history in the early universe based on this project.


title:
A General Formulation of the Source Confusion Statistics and Application
  to Infrared Galaxy Surveys

abstract:
  Source confusion has been a long-standing problem in the astronomical
history. In the previous formulation, sources are assumed to be distributed
homogeneously on the sky. This fundamental assumption is not realistic in many
applications. In this work, by making use of the point field theory, we derive
general analytic formulae for the confusion problems with arbitrary
distribution and correlation functions. As a typical example, we apply these
new formulae to the source confusion of infrared galaxies. We first calculate
the confusion statistics for power-law galaxy number counts as a test case.
When the slope of differential number counts, \gamma, is steep, the confusion
limits becomes much brighter and the probability distribution function (PDF) of
the fluctuation field is strongly distorted. Then we estimate the PDF and
confusion limits based on the realistic number count model for infrared
galaxies. The gradual flattening of the slope of the source counts makes the
clustering effect rather mild. Clustering effects result in an increase of the
limiting flux density with \sim 10%. In this case, the peak probability of the
PDF decreases up to \sim 15% and its tail becomes heavier.


title: The Fundamental Plane of Field Early Type Galaxies at z=1

abstract:
  We present deep VLT spectra of early type galaxies at z~1 in the Chandra Deep
Field South, from which we derive velocity dispersions. Together with
structural parameters from Hubble Space Telescope imaging, we can study the
Fundamental Plane for field early type galaxies at that epoch. We determine
accurate mass-to-light ratios and colors for four field early type galaxies in
the redshift range 0.96<z<1.14, and two with 0.65<z<0.70.
  The galaxies were selected by color and morphology, and have generally red
colors. Their velocity dispersions show, however, that they have a considerable
spread in mass-to-light ratios (factor of 3). We find that the colors and
directly measured mass-to-light ratios correlate well, demonstrating that the
spread in mass-to-light ratios is real and reflects variations in stellar
populations.
  The most massive galaxies have mass-to-light ratios comparable to massive
cluster galaxies at similar redshift, and therefore have stellar populations
which formed at high redshift (z>2). The lower mass galaxies at z~1 have a
lower average mass-to-light ratio, and one is a genuine 'E+A' galaxy. The
mass-to-light ratios indicate that their luminosity weighted ages are a factor
of three younger at the epoch of observation, due to either a late formation
redshift, or due to late bursts of star formation contributing 20-30% of the
mass.


title:
Molecular Inventories and Chemical Evolution of Low-mass Protostellar
  Envelopes

abstract:
  This paper presents the first substantial study of the chemistry of the
envelopes around a sample of 18 low-mass pre- and protostellar objects for
which physical properties have previously been derived from radiative transfer
modeling of their dust continuum emission. Single-dish line observations of 24
transitions of 9 molecular species (not counting isotopes) including HCO+,
N2H+, CS, SO, SO2, HCN, HNC, HC3N and CN are reported. The line intensities are
used to constrain the molecular abundances by comparison to Monte Carlo
radiative transfer modeling of the line strengths. An empirical chemical
network is constructed on the basis of correlations between the abundances of
various species. For example, it is seen that the HCO+ and CO abundances are
linearly correlated, both increasing with decreasing envelope mass. Species
such as CS, SO and HCN show no trend with envelope mass. In particular no trend
is seen between ``evolutionary stage'' of the objects and the abundances of the
main sulfur- or nitrogen-containing species. Among the nitrogen-bearing species
abundances of CN, HNC and HC3N are found to be closely correlated, which can be
understood from considerations of the chemical network. The CS/SO abundance
ratio is found to correlate with the abundances of CN and HC3N, which may
reflect a dependence on the atomic carbon abundance. An anti-correlation is
found between the deuteration of HCO+ and HCN, reflecting different temperature
dependences for gas-phase deuteration mechanisms. The abundances are compared
to other protostellar environments. In particular it is found that the
abundances in the cold outer envelope of the previously studied class 0
protostar IRAS16293-2422 are in good agreement with the average abundances for
the presented sample of class 0 objects.


title:
Ionizing Photon Emission Rates from O- and Early B-type Stars and
  Clusters

abstract:
  We present new computations of the ionizing spectral energy distributions
(SEDs) and Lyman continuum (Lyc) and HeI continuum photon emission rates, for
hot O-type and early B-type stars. We consider solar metallicity stars, with
effective temperatures ranging from 25,000 to 55,000 K and surface gravities
(cm s^-2) logg ranging from 3 to 4, covering the full range of spectral types
and luminosity classes for hot stars. We use our updated (WM-basic) code to
construct radiation-driven wind atmosphere models for hot stars. Our models
include the coupled effects of hydrodynamics and non-LTE radiative transfer in
spherically outflowing winds, including the detailed effects of metal line
blocking and line blanketing on the radiative transfer and energy balance. We
incorporate our hot-star models into our population synthesis code (STARS), and
we compute the time-dependent SEDs and resulting Lyc and HeI emission rates for
evolving star clusters. We present results for continuous and impulsive star
formation for a range of assumed stellar initial mass functions.


title:
Understanding B-type Supergiants in the Low Metallicity Environment of
  the SMC

abstract:
  Spectroscopic analyses of 7 SMC B-type supergiants and 1 giant have been
undertaken using high resolution optical data obtained on the VLT with UVES.
FASTWIND, a non-LTE, spherical,line-blanketed model atmosphere code was used to
derive atmospheric and wind parameters of these stars as well as their absolute
abundances. The implications of these results for stellar evolution and line
driven wind theory are discussed.


title: The cosmic evolution of quasar host galaxies

abstract:
  We present near-infrared imaging of the host galaxies of 17 quasars in the
redshift range 1 < z < 2, carried out at the ESO VLT UT1 8m telescope under
excellent seeing conditions (~0.4 arcsec). The sample includes radio-loud (RLQ)
and radio-quiet (RQQ) quasars with similar distribution of redshift and optical
luminosity. For all the observed objects but one we have derived the global
properties of the surrounding nebulosity. The host galaxies of both types of
quasars follow the expected trend in luminosity of massive ellipticals
undergoing simple passive evolution, but there is a systematic difference by a
factor ~2 in the host luminosity between RLQs and RQQs (M_K(RLQ) = -27.55 +-
0.12 and M_K(RQQ) = -26.83 +- 0.25). Comparison with quasar hosts at similar
and lower redshift indicates that the difference in the host luminosity between
RLQs and RQQs remains the same from z = 2 to the present epoch. No significant
correlation is found between the nuclear and the host luminosities. Assuming
that the host luminosity is proportional to the black hole mass, as observed in
nearby massive spheroids, these quasars emit at very different levels (spread
\~1.5dex) with respect to their Eddington luminosity and with the same
distribution for RLQs and RQQs. Apart from a factor of ~2 difference in
luminosity, the hosts of RLQs and RQQs appear to follow the same cosmic
evolution as massive inactive spheroids. Our results support a view where
nuclear activity can occur in all luminous ellipticals without producing a
significant change in their global properties and evolution. Quasar hosts
appear to be already well formed at z ~2, in disagreement with models for the
joint formation and evolution of galaxies and active nuclei based on the
hierarchical structure formation scenario.


title: X-ray variability of the Narrow Line Seyfert 1 Galaxy PKS 0558-504

abstract:
  We present results from several XMM-Newton observations of the radio loud
Narrow-line Seyfert 1 galaxy (NLS1) PKS 0558-504. We find evidence for strong
and persistent X-ray variability, both on short and long time-scales. On short
time scales of ~2 hours the source varies smoothly by 15-20%; long term
variations by a factor of >2 could not be resolved in the relatively short
exposures: we find the source mostly in a `low' state, in 2 out of the 11
observations in a `high state'. X-ray flares seem to be recurrent with a time
scale of ~24 ksec which, if interpreted as the Keplerian time scale in the
disc, would place the emission region just outside the last stable orbit. The
X-ray spectrum of PKS 0558-504 can be well fitted by two Comptonization
components, one at moderate temperatures of kT ~ 4.5 keV and optical depths of
\~ 2, the other at high temperatures kT > 50 keV and low optical depths < 1.0.
These parameters are, however, subject to large errors due to the inherent
degeneracy of the Comptonization models. Flux variations of the source are
caused by changes of the colder component only, the hot component with
parameters very similar to those of BLS1 galaxies, stays constant. All results
fit nicely the picture that NLS1 galaxies are lower mass objects, accreting
close to the Eddington rate emitting X-rays from a very active magnetically
powered accretion disc corona.


title:
The detailed Fundamental Plane of two high redshift clusters: MS 2053-04
  at z=0.58 and MS 1054-03 at z=0.83

abstract:
  We study the fundamental plane relation in high redshift clusters using a
sample of 26 galaxies in MS 2053-04 (z=0.583) and 22 galaxies in MS 1054-03
(z=0.83). The zeropoint and scatter are compared to results for lower redshift
clusters in order to trace evolutionary effects. Furthermore, our large sample
enables us to investigate correlations between residuals from the fundamental
plane and other characteristics of the galaxies, such as color, $H\beta$
linestrength, spatial distribution, and mass. The observed scatter of the
early-type galaxies with sigma > 100 km/s around the fundamental plane is 0.134
and 0.106 in log r_e for MS 2053-04 and MS 1054-03 respectively. The residuals
from the fundamental plane of MS 2053-04 are correlated with residuals from the
$H\beta - \sigma$ relation, suggesting that stellar populations are playing a
role in shaping the fundamental plane. The measured evolution in log M/L is
influenced by selection effects, as galaxies with lower M/L in the Johnson
B-band enter a magnitude-limited sample more easily. When we select high mass
early-type galaxies to avoid this bias, we find $\log M/L_B \sim -0.47 z$ and a
formation redshift $z_{form} \sim 2.95$, similar to earlier results.


title:
Red variables in the OGLE-II database. II. Comparison of the Large and
  Small Magellanic Clouds

abstract:
  We present period-luminosity relations for more than 3,200 red variable stars
in the Small Magellanic Cloud observed in the second phase of the Optical
Gravitational Lensing Experiment (OGLE-II). Periods of multiply-periodic light
curve solutions combined with the single-epoch 2MASS JHK_S magnitudes, reveal
very similar distributions to those for the Large Magellanic Cloud in Paper I.
The main features include four pulsating Asymptotic Giant Branch (AGB) ridges,
three distinct short-period sequences below the tip of the Red Giant Branch and
two long-period sequences of ambiguous origin. We derive a relative distance
modulus of the Clouds from the period-luminosity distributions for all stars of
Delta mu_0=0.44 mag, which is in good agreement with recent independent
results. The tip of the Red Giant Branch shows a colour and metallicity
dependence that is in excellent agreement with the empirical results for
globular clusters. We conclude that most variable stars below the TRGB are
indeed RGB stars.


title:
Magnetic topology and surface differential rotation on the K1 subgiant
  of the RS CVn system HR 1099

abstract:
  We present here spectropolarimetric observations of the RS CVn system HR 1099
(V711 Tau) secured from 1998 February to 2002 January with the
spectropolarimeter MuSiCoS at the Telescope Bernard Lyot (Observatoire du Pic
du Midi, France). We apply Zeeman-Doppler Imaging and reconstruct brightness
and magnetic surface topologies of the K1 primary subgiant of the system, at
five different epochs. We confirm the presence of large, axisymmetric regions
where the magnetic field is mainly azimuthal, providing further support to the
hypothesis that dynamo processes may be distributed throughout the whole
convective zone in this star. We study the short-term evolution of surface
structures from a comparison of our images with observations secured at
close-by epochs by Donati et al. (2003) at the Anglo-Australian Telescope. We
conclude that the small-scale brightness and magnetic patterns undergo major
changes within a timescale of 4 to 6 weeks, while the largest structures remain
stable over several years. We report the detection of a weak surface
differential rotation (both from brightness and magnetic tracers) indicating
that the equator rotates faster than the pole with a difference in rotation
rate between the pole and the equator about 4 times smaller than that of the
Sun. This result suggests that tidal forces also impact the global dynamic
equilibrium of convective zones in cool active stars.


title: Scaling laws in X-ray Galaxy Clusters at redshift between 0.4 and 1.3

abstract:
  (Abriged) We present a study of the integrated physical properties of a
sample of 28 X-ray galaxy clusters observed with Chandra at redshift between
0.4 and 1.3. In particular, we have twelve objects in the redshift range
0.4-0.6, five between 0.6 and 0.8, seven between 0.8 and 1 and four at z>1,
compounding the largest sample available for such a study. We focus
particularly on the properties and evolution of the X-ray scaling laws. We fit
both a single and a double beta-model with the former which provides a good
representation of the observed surface brightness profiles, indicating that
these clusters do not show any significant excess in their central brightness.
By using the best-fit parameters of the beta-model together with the measured
emission-weighted temperature (in the range 3-11 keV), we recover gas
luminosity, gas mass and total gravitating mass out to R500. We observe scaling
relations steeper than expected from self-similar model by a significant (>3
sigma) amount in the L-T and Mgas-T relations. We detect hints of negative
evolution in the L-T, Mgas-T and L-Mtot relations, thus suggesting that systems
at higher redshift have lower X-ray luminosity and gas mass for fixed
temperature. In particular, when the 16 clusters at z>0.6 are considered, the
evolution becomes more evident and its power-law modelization is a
statistically good description of the data.


title: High Resolution mid-Infrared Imaging of SN 1987A

abstract:
  Using the Thermal-Region Camera and Spectrograph (T-ReCS) attached to the
Gemini South 8m telescope, we have detected and resolved 10 micron emission at
the position of the inner equatorial ring (ER) of supernova SN 1987A at day
6067. ``Hot spots'' similar to those found in the optical and near-IR are
clearly present. The morphology of the 10 micron emission is globally similar
to the morphology at other wavelengths from X-rays to radio. The observed
mid-IR flux in the region of SN1987A is probably dominated by emission from
dust in the ER. We have also detected the ER at 20 micron at a 4 sigma level.
Assuming that thermal dust radiation is the origin of the mid-IR emission, we
derive a dust temperature of 180^{+20}_{-10} K, and a dust mass of 1.- 8.
10^{-5} Mo for the ER. Our observations also show a weak detection of the
central ejecta at 10 micron. We show that previous bolometric flux estimates
(through day 2100) were not significantly contaminated by this newly discovered
emission from the ER. If we assume that the energy input comes from radioactive
decays only, our measurements together with the current theoretical models set
a temperature of 90 leq T leq 100 K and a mass range of 10^{-4} - 2. 10^{-3} Mo
for the dust in the ejecta. With such dust temperatures the estimated thermal
emission is 9(+/-3) 10^{35} erg s^{-1} from the inner ring, and 1.5 (+/-0.5)
10^{36} erg s^{-1} from the ejecta. Finally, using SN 1987A as a template, we
discuss the possible role of supernovae as major sources of dust in the
Universe.


title:
The influence of density stratification and multiple nonlinearities on
  solar torsional oscillations

abstract:
  Analyses of recent helioseismic data have produced ample evidence for
substantial dynamical variation of the differential rotation within the solar
convection zone. Given the inevitable difficulties in resolving the precise
nature of variations at deeper layers, much effort has recently gone into
determining theoretically the expected modes of behaviour, using nonlinear
dynamo models. Two important limitations of these models are that they have so
far included only one form of nonlinearity, and as yet they have not taken into
account the density stratification in the solar convection zone. Here we
address both of these issues by studying the effects of including density
stratification, as well as including an alpha--quenching nonlinearity in
addition to the previously studied effects of the Lorentz force on the
differential rotation. We find that observationally important features found in
the earlier uniform density models remain qualitatively unchanged, although
there are quantitative differences. This is important as it provides more
realistic theoretical predictions to be compared with and guide observations,
especially in the deeper regions where the uncertainties in the inversions are
larger. However the presence of an effective alpha-quenching nonlinearity
significantly reduces the amplitudes of the oscillations.


title: Eclipsing binaries in open clusters. I. V615 Per and V618 Per in h Per

abstract:
  We derive absolute dimensions for two early-type main sequence detached
eclipsing binaries in the young open cluster h Persei (NGC 869). V615 Persei
has a spectral type of B7V and a period of 13.7d. V618 Persei is A2V and has a
period of 6.4d. New ephemerides are calculated for both systems. The masses of
the component stars have been derived using high-resolution spectroscopy and
are 4.08+/-0.06 Msun and 3.18+/-0.05 Msun for V615 Per and 2.33+/-0.03 Msun and
1.56+/-0.02 Msun for V618 Per. The radii have been measured by fitting the
available light curves using EBOP and are 2.29+/-0.14 Rsun and 1.90+/-0.09 Rsun
for V615 Per and 1.64+/-0.07 Rsun and 1.32+/-0.07 Rsun for V618 Per. By
comparing the observed spectra of V615 Per to synthetic spectra from model
atmospheres we find that the effective temperatures of the two stars are
15000+/-500 K and 11000+/-500 K. The equatorial rotational velocities of the
primary and secondary components of V615 Per are 28+/-5 km/s and 8+/-5 km/s,
respectively. Both components of V618 Per rotate at 10+/-5 km/s. The equatorial
rotational velocities for synchronous rotation are about 10 km/s for all four
stars. The timescales for orbital circularisation for both systems, and the
timescale for rotational synchronisation of V615 Per, are much greater than the
age of h Per. Their negligible eccentricities and equatorial rotational
velocities therefore support the hypothesis that they were formed by 'delayed
breakup'. We have compared the radii of these stars to models by the Granada
and the Padova groups for stars of the same masses but different compositions.
We conclude that the metallicity of the stars is about Z=0.01. This appears to
be the first estimate of the bulk metallicity of h Per. Recent photometric
studies have assumed a solar metallicity so their results should be reviewed.


title: HI holes in galactic disks: Tracing the dark matter distribution

abstract:
  Multiple SN explosions in disk galaxies efficiently evacuate gas and form
cavities with the sizes and shapes of the surrounding envelopes determined by
the total amount of injected energy and by the initial gas distribution. Such
cavities are seen as HI holes when observed in face-on galaxies. Gas
hydrodynamics simulations are performed to obtain the quantitative
characteristics of HI holes that could serve for the determination of the gas
vertical scale height and the corresponding dark matter content and its
distribution. Among these characteristics is the ratio of the maximum column
density in the HI ring surrounding the hole to the background HI column density
and the vertical expansion velocity of gas in the HI ring. We show that in some
cases the extragalactic background ionizing radiation may produce HI holes in
the outer regions of galaxies, and can account for the existence of HI holes in
nearby face-on galaxies with the apparent lack of an underlying stellar
population.


title: Influence of Solar Activity on State of Wheat Market in Medieval England

abstract:
  The database of Prof. Rogers (1887), which includes wheat prices in England
in the Middle Ages, was used to search for a possible influence of solar
activity on the wheat market. We present a conceptual model of possible modes
for sensitivity of wheat prices to weather conditions, caused by solar cycle
variations, and compare expected price fluctuations with price variations
recorded in medieval England.
  We compared statistical properties of the intervals between wheat price
bursts during years 1249-1703 with statistical properties of the intervals
between minimums of solar cycles during years 1700-2000. We show that
statistical properties of these two samples are similar, both for
characteristics of the distributions and for histograms of the distributions.
We analyze a direct link between wheat prices and solar activity in the 17th
Century, for which wheat prices and solar activity data (derived from 10Be
isotope) are available. We show that for all 10 time moments of the solar
activity minimums the observed prices were higher than prices for the
correspondent time moments of maximal solar activity (100% sign correlation, on
a significance level < 0.2%). We consider these results as a direct evidence of
the causal connection between wheat prices bursts and solar activity.


title: Jet termination in wide-angle tailed radio sources

abstract:
  Wide-angle tail radio galaxies (WATs) are an uncommon class of radio sources
with luminosities near the FRI/FRII break, and are usually associated with
central cluster galaxies. Their defining characteristic when imaged sensitively
at high resolution is their twin, well-collimated jets, which can persist with
low opening angle for tens of kpc before flaring into long, often bent plumes.
Although several models for the jet termination have been proposed, the
majority of them are unsatisfactory when confronted with observations. Here we
present the results of a programme of radio observations made with the aims of
showing that objects classified as WATs do all have well-collimated jets and
seeing in detail how the jets disrupt as they enter the plumes. We show that
compact, `hotspot-like' features at the ends of the jets are common but by no
means universal, and discuss the constraints that this places on models of the
jet-plume transition. We discuss the properties of the observed well-collimated
jets and, using relativistic beaming models, estimate their speed to be ~ 0.3c.
Finally, we show that the distance from the galactic centre at which the base
of the plume is found is related to the temperature of the host cluster.


title: The ionization equilibrium of iron in H II regions

abstract:
  We study the ionization equilibrium of Fe using photoionization models that
incorporate improved values for the ionization and recombination cross-sections
and the charge-exchange rates for the Fe ions. The previously available
photoionization models predict concentrations of Fe3+ which are a factor of 3-8
higher than the values inferred from emission lines of [Fe III] and [Fe IV].
Our new models reduce these discrepancies to factors of 2-5. We discuss the
possible reasons behind the remaining discrepancies and present an updated
ionization correction factor for obtaining the Fe abundance from the Fe++
abundance.


title: [O I] 63 micron Emission from High and Low Luminosity AGN Galaxies

abstract:
  The Infrared Space Observatory was used to search for a tracer of the warm
and dense neutral interstellar medium, the [O I] 63.18 micron line, in four
ultraluminous IRAS sources lying at redshifts between 0.6 and 1.4. While these
sources are quasars, their infrared continuum emission suggests a substantial
interstellar medium. No [O I] flux was securely detected after probing down to
a 3 sigma sensitivity level sufficient for detecting line emission in
starbursts with similar continuum emission. However, if the detection threshold
is slightly relaxed, one target is detected with 2.7 sigma significance. For
this radio-quiet quasar there is likely a substantial dense and warm
interstellar medium; the upper limits for the three radio-loud sources do not
preclude the same conclusion. Using a new, uniformly-processed database of the
ISO extragalactic far-infrared spectroscopy observations, it is shown that
nearby Seyfert galaxies typically have higher [O I]-to-far-infrared ratios than
do normal star-forming galaxies, so the lack of strong [O I] 63 micron emission
from these high-redshift ultraluminous sources cannot be attributed to their
active cores.


title: Cold Dust in Early-Type Galaxies. I. Observations

abstract:
  We describe far infrared observations of early-type galaxies selected from
the ISO archive. This rather inhomogeneous sample includes 39 giant elliptical
galaxies and 14 S0 (or later) galaxies. These galaxies were observed using a
variety of different observing modes, each of which requires different and
often rather elaborate photometric reduction procedures. The ISO background
data agrees well with COBE-DIRBE results to which we have renormalized our
calibrations. As a further check, the ISO fluxes from galaxies at 60 and 100
microns agree very well with those previously observed with IRAS at these
wavelengths. The spatial resolution of ISO is several times greater than that
of IRAS and the ISO observations extend out to 200 microns which views a
significantly greater mass of colder dust not assessable to IRAS. Most of the
galaxies are essentially point sources at ISO resolution, but a few are clearly
extended at FIR wavelengths with image sizes that increase with FIR wavelength.
The integrated far infrared luminosities do not correlate with optical
luminosities, suggesting that the dust may have an external, merger-related
origin. In general the far infrared spectral energy distributions can be
modeled with dust at two temperatures, ~ 43 K and ~ 20 K, which probably
represent limits of a continuous range of temperatures. The colder dust
component dominates the total mass of dust, which is typically more than ten
times larger than the dust masses previously estimated for the same galaxies
using IRAS observations. For S0 galaxies we find that the optically normalized
far-infrared luminosity $L_{FIR} / L_B$ correlates strongly with the
mid-infrared luminosity $L_{15\mu\rm{m}} / L_B$, but that correlation is weaker
for elliptical galaxies.


title: Neutrinos and Gamma Rays from Photomeson Processes in Gamma Ray Bursts

abstract:
  Acceleration of high-energy hadrons in GRB blast waves will be established if
high-energy neutrinos are detected from GRBs. Recent calculations of photomeson
neutrino production are reviewed, and new calculations of high-energy neutrinos
and the accompanying hadronic cascade radiation are presented. If hadrons are
injected in GRB blast waves with an energy corresponding to the measured hard
X-ray/soft gamma-ray emission, then only the most powerful bursts at fluence
levels >~ 3e-4 erg cm^{-2} offer a realistic prospect for detection of muon
neutrinos. Detection of high-energy neutrinos are likely if GRB blast waves
have large baryon loads and Doppler factors <~ 200. Significant limitations on
the hadronic baryon loading and the number of expected neutrinos are imposed by
the fluxes from pair-photon cascades initiated in the same processes that
produce neutrinos.


title: Mapping the inner regions of MCG-6-30-15 with XMM-Newton

abstract:
  Timing analysis of a ~95 ks long XMM-Newton observation of the Seyfert 1
galaxy MCG-6-30-15 is presented. Model-independent tools have been used with
the intent of resolving the different components that produce the observed flux
and spectral variations down to timescales as short as ~300 s. We find that the
fractional variability is possibly due to a variable power law component in the
hard band, and a slower thermal component at softer energies, but the data do
not rule out effects due to the warm absorber. The most relevant result of this
work is the first detection of a significant enhancement of the fractional
variability in the ~4.7-5.8 keV energy band compared to the underlying
continuum. This represents one of the strongest, model-independent, pieces of
evidence to date for the presence of redshifted relativistic matter accreting
into the black hole. During the brightest flare of the observation, a
soft-to-hard time lag of ~600 s is measured. A very significant increase of the
iron line intensity is observed ~3000 s after this flare. In the framework of a
disk-corona model and assuming the soft-to-hard time lag is due to
Comptonization, these findings make it possible to estimate the electron
density and the dimensions of the flare region and the disk-flare distance.


title:
On Hadronic Models for the Anomalous $\gamma$-ray Emission Component in
  GRB 941017

abstract:
  Gonz\'alez et al. (2003) have reported the discovery of an anomalous
radiation component from ~ 1 -- 200 MeV in GRB 941017. This component varies
independently of and contains >~ 3 times the energy found in the prompt ~ 50
keV -- 1 MeV radiation component that is well described by the relativistic
synchrotron-shock model. Acceleration of hadrons to very high energies by GRBs
could give rise to a separate emission component. Two models, both involving
acceleration of ultra-high energy cosmic rays with subsequent photomeson
interactions, are considered. The first involves a pair-photon cascade
initiated by photohadronic processes in the GRB blast wave. Calculations
indicate that the cascade produces a spectrum that is too soft to explain the
observations. A second model is proposed where photopion interactions in the
GRB blast-wave shell give rise to an escaping collimated neutron beam. The
outflowing neutrons undergo further photopion interactions to produce a beam of
hyper-relativistic electrons that can lose most of their energy during a
fraction of a gyroperiod in the Gauss-strength magnetic fields found in the
circumburst medium. This secondary electron beam produces a hard synchrotron
radiation spectrum that could explain the anomalous component in GRB 941017.


title:
A Review of the Current Status of Follow-Up Techniques to Study Known
  Extrasolar Planets

abstract:
  I present a review of observational efforts to study known extrasolar planets
by methods that are complementary to the radial velocity technique. I describe
the current state of attempts to detect and characterize such planets by
astrometry, by reflected light, by thermal emission, by transit photometry, by
atmospheric transmission spectroscopy, by planet-induced chromospheric
activity, and by long-wavelength radio emission. With a few exceptions,these
efforts have yielded only upper limits. Nonetheless, the diversity and vivacity
of these pursuits has rapidly pushed many of these techniques into the realm
where realistic models of the planets and their atmospheres can now be
confronted.


title: Halo asphericity and the shear 3-pt function

abstract:
  We demonstrate through the use of a simple toy model that asphericity in dark
matter halos has a measurable effect on the configuration dependence of the
weak lensing shear 3-point function at small scales. This sensitivity provides
a way, in principle, to measure the shapes of dark matter halos. The
distribution of halo ellipticities should be included in models aiming at a
high fidelity prediction of n-point shear correlation statistics.


title: Relativistic Outflows in Active Galactic Nuclei

abstract:
  There are observational indications that relativistic outflows in AGNs are
accelerated over distances that far exceed the scale of the central engine.
Examples include the radio galaxy NGC 6251, where knots in the radio jets were
inferred to accelerate from ~0.13c at a distance of ~0.53 pc from the galactic
nucleus to ~0.42c at r=1.0 pc, and the quasar 3C 345, where the Lorentz factor
of the radio knot C7 was deduced to increase from ~5 to >10 as it moved from
r=3 pc to r=20 pc. It is argued, using exact semianalytic solutions of the
relativistic MHD equations, that this behavior is a signature of magnetic
acceleration. The same basic driving mechanism may apply to the relativistic
jets in AGNs, gamma-ray burst sources, and microquasars.


title: Galactic Chemical Evolution

abstract:
  The primary present-day observables upon which theories of galaxy evolution
are based are a system's morphology, dynamics, colour, and chemistry.
Individually, each provides an important constraint to any given model; in
concert, the four represent a fundamental (intractable) boundary condition for
chemodynamical simulations. We review the current state-of-the-art
semi-analytical and chemodynamical models for the Milky Way, emphasising the
strengths and weaknesses of both approaches.


title: A Disk Shadow Around the Young Star ASR 41 in NGC 1333

abstract:
  We present images of the young stellar object ASR 41 in the NGC 1333 star
forming region at the wavelengths of H_alpha and [SII] and in the I, J, H, and
K-bands.
  ASR 41 has the near-infrared morphology of an edge-on disk object, but
appears an order of magnitude larger than typical systems of this kind.
  We also present detailed models of the scattering and radiative transfer in
systems consisting of a young star surrounded by a proto-planetary disk, and
the whole system being embedded in either an infalling envelope or a uniform
molecular cloud. The best fit to the observed morphology can be achieved with a
disk of approx. 200 AU diameter, immersed in a low density cloud. The low cloud
density is necessary to stay below the sub-mm flux upper limits and to preserve
the shadow cast by the disk via single scattering.
  The results demonstrate that ASR 41 is probably not inherently different from
typical edge-on disk objects, and that its large apparent size is due to the
shadow of a much smaller disk being projected into the surrounding dusty
molecular material.


title: L1157: Interaction of the molecular outflow with the Class~0 environment

abstract:
  We present high angular resolution interferometric observations of the dust
continuum at 2.7 and 1.3 mm, and of the HC3N (12-11) and C18O (2-1) emission
around L1157-mm, a Class~0 object that drives a spectacular molecular outflow.
The millimeter dust emission is clearly resolved into two components, a
flattened compact source of ~450 x 250 AU at 1.3 mm, and mass ~0.1 Msun, plus
an extended envelope of ~3000 AU at 1.3 mm, and mass ~1.1 Msun. The millimeter
spectral index varies throughout the region, with the lower value found toward
the compact protostar, possibly indicating grain growth in the denser regions.
A strong interaction between the molecular outflow and the close protostellar
environment is taking place and affects the structure of the innermost parts of
the envelope. This is shown by the spatial coincidence between the molecular
outflow and the dust (1.3 mm continuum) and HC3N emission: both tracers show
structures associated to the edges of the outflow lobes. Basically, the global
picture sketched for the Class 0 object L1157-mm by Gueth et al. (1997) is
supported. We find possible evidence of infall, but we do not detect any
velocity gradient indicative of a rotating circumstellar disk.


title:
Dust masses and star formation in bright IRAS galaxies Application of a
  physical model for the interpretation of FIR observations

abstract:
  We address the problem of modeling the far-infrared (FIR) spectrum and
deriving the star-formation rate (SFR) and the dust mass of spiral galaxies. We
use the realistic physical model of Popescu et al. (2000) to describe the
overall ultra-violet (UV), optical and FIR spectral energy distribution (SED)
of a spiral galaxy. The model has only three free parameters: SFR, dust mass,
and the fraction of the UV radiation which is absorbed locally by dense dust in
the HII regions. Using this model, we are able to fit well the FIR spectra of
62 bright, IRAS galaxies from the "SCUBA Local Universe Galaxy Survey" of Dunne
et al.(2000). As a result, we are able to determine, among others, their SFR
and dust mass. We find that, on average, the SFR (in absolute units), the
star-formation efficiency, the SFR surface density, and the ratio of FIR
luminosity over the total intrinsic luminosity, are larger than the respective
values of typical spiral galaxies of the same morphological type. We also find
that the mean gas-to-dust mass ratio is close to the Galactic value, while the
average central face-on optical depth of these galaxies in the V band is 2.3.
Finally, we find a strong correlation between SFR or dust mass and observed FIR
quantities like total FIR luminosity or FIR luminosity at 100 and 850
$\mathrm{\mu m}$. These correlations yield well defined relations, which can be
used to determine a spiral galaxy's SFR and dust-mass content from FIR
observations.


title: Two spectral states of the transient X-ray burster SAX J1747.0-2853

abstract:
  The neutron star binary SAX J1747.0-2853, located in the Galactic Center
region at about 0.5 deg from Sgr A* and at a distance of 9 kpc, has been
observed in outburst four times (1998, 1999, 2000 and 2001) by BeppoSAX and
RossiXTE. At the time of its discovery in 1998 the source was observed in a
low/hard state, showing a hard tail with a high energy cutoff of 70 keV. About
two years later the source reappeared about one order of magnitude brighter in
the X-rays (0.5-10 keV) and with a significantly steeper spectrum. As was the
case for the low state, the data could be fitted by an input model based on two
continuum primary components: a) a soft thermal excess, which is ~4 times more
luminous than the one found in hard state; b) a non-thermal component which is
compatible with either a power-law or a comptonization spectrum. The soft
component is equally well described by pure blackbody or multi-color disk
emission, with significantly higher temperature than observed in low state
(~1.3 vs. the ~0.5 keV assuming pure blackbody). For this model, the flux of
the non-thermal component below ~10 keV is a significant fraction of the total
X-ray flux, i.e. greater than ~50% in the 2-10 keV band.


title:
Log-parabolic spectra and particle acceleration in the BL Lac object Mkn
  421: spectral analysis of the complete BeppoSAX wide band X-ray data set

abstract:
  We report the results of a new analysis of 13 wide band BeppoSAX observations
of the BL Lac object Mkn 421. The data from LECS, MECS and PDS, covering an
energy interval from 0.1 to over 100 keV, have been used to study the spectral
variability of this source. We show that the energy distributions in different
luminosity states can be fitted very well by a log-parabolic law
F(E)=K*(E/E_1)^(-(a+b*Log(E/E_1))), which provides good estimates of the energy
and flux of the synchrotron peak in the SED. In the first four short
observations of 1997 Mkn 421 was characterized by a very stable spectral shape,
with average values a=2.25 and b=0.45. In the observations of 1998 smaller
values for both parameters, a~2.07 and b~0.34, were found and the peak energy
in the SED was in the range 0.5-0.8 keV. Also in the observations of May 1999
and April-May 2000 the log-parabolic model gave a satisfactory description of
the overall SED of Mkn 421. In particular, in the observations of spring 2000
the source was brighter than the other observations and showed a large change
of the spectral curvature. Spectral parameters estimates gave a~1.8 and b~0.19
and the energy of the maximum in the SED moved to the range 1-5.5 keV. We give
a possible interpretation of the log-parabolic spectral model in terms of
particle acceleration mechanisms. An energy distribution of emitting particles
with curvature close to the one observed can be explained by a simple model for
statistical acceleration with the assumption that the probability for a
particle to increase its energy is a decreasing function of the energy itself.
A consequence of this mechanism is the existence of a linear relation between
the spectral parameters a and b, well confirmed by the estimated values of
these two parameters for Mkn421.(Abridged)


title: The 3-D ionization structure and evolution of NGC 7009 (Saturn Nebula)

abstract:
  Tomographic and 3-D analyses for extended, emission-line objects are applied
to long-slit ESO NTT + EMMI high-resolution spectra of the intriguing planetary
nebula NGC 7009, covered at twelve position angles. We derive the gas expansion
law, the diagnostics and ionic radial profiles, the distance and the central
star parameters, the nebular photo-ionization model and the spatial recovery of
the plasma structure and evolution. The Saturn Nebula (distance~1.4 kpc,
age~6000 yr, ionized mass~0.18 Mo) consists of several interconnected
components, characterized by different morphology, physical conditions,
excitation and kinematics. The internal shell, the main shell, the streams and
the ansae expand at V(exp)~4.0xR" km/s, the outer shell, the caps and the
equatorial pseudo-ring at V(exp)~3.15xR" km/s, and the halo at V(exp)~10 km/s.
We compare the radial distribution of the physical conditions and the line
fluxes observed in the eight sub-systems with the theoretical profiles coming
from the photo-ionization code CLOUDY, inferring that all the spectral
characteristics of NGC 7009 are explainable in terms of photo-ionization by the
central star, a hot (logT*~4.95) and luminous (log L*/Lo~3.70) 0.60--0.61 Mo
post--AGB star in the hydrogen-shell nuclear burning phase. The 3--D shaping of
the Saturn Nebula is discussed within an evolutionary scenario dominated by
photo-ionization and supported by the fast stellar wind: it begins with the
superwind ejection, passes through the neutral, transition phase (lasting ~
3000 yr), the ionization start (occurred ~2000 yr ago), and the full ionization
of the main shell (~1000 yr ago), at last reaching the present days: the whole
nebula is optically thin to the UV stellar flux, except the caps and the ansae.


title: LensClean revisited

abstract:
  We discuss the LensClean algorithm which for a given gravitational lens model
fits a source brightness distribution to interferometric radio data in a
similar way as standard Clean does in the unlensed case. The lens model
parameters can then be varied in order to minimize the residuals and determine
the best model for the lens mass distribution. Our variant of this method is
improved in order to be useful and stable even for high dynamic range systems
with nearly degenerated lens model parameters. Our test case B0218+357 is
dominated by two bright images but the information needed to constrain the
unknown parameters is provided only by the relatively smooth and weak Einstein
ring. The new variant of LensClean is able to fit lens models even in this
difficult case. In order to allow the use of general mass models with
LensClean, we develop the new method LenTil which inverts the lens equation
much more reliably than any other method. This high reliability is essential
for the use as part of LensClean. Finally a new method is developed to produce
source plane maps of the unlensed source from the best LensClean brightness
models. This method is based on the new concept of dirty beams in the source
plane.
  The application to the lens B0218+357 leads to the first useful constraints
for the lens position and thus to a result for the Hubble constant. These
results are presented in an accompanying Paper II, together with a discussion
of classical lens modelling for this system.


title:
Models for the lens and source of B0218+357 - A LensClean approach to
  determine H0

abstract:
  B0218+357 is one of the most promising systems to determine the Hubble
constant from gravitational lenses. Consisting of two bright resolved images
plus an Einstein ring, it provides better constraints for the mass model than
other systems. The main problem left until now was the poorly determined
position of the lensing galaxy.
  After presenting results from classical lens modelling, we apply our improved
version of LensClean which utilizes the Einstein ring for lens modelling
purposes. The primary result using isothermal models is a well defined lens
position which allows the first reliable measurement of the Hubble constant
from this system. The result of H0=(78+-6) km/s/Mpc (2 sigma) is high compared
with other lenses but compatible with the HST key project and WMAP results. We
furthermore discuss effects of different radial mass profiles. The power-law
exponent of the potential is constrained by VLBI data to be beta=1.04+-0.02,
very close to isothermal. The effect on H0 is expected to be very small.
  We also present a composite map (lensed and unlensed) which shows the rich
structure of B0218+357 on scales from milli-arcseconds to arcseconds. Finally
we use a comparison of observations at different frequencies to investigate the
question of possible weakening of one of the images by propagation effects
and/or source shifts with frequency. The data clearly favour the model of
significant extinction without noticeable source position shifts.
  The technical details of our variant of the LensClean method are presented in
the accompanying Paper I.


title: SN 2002lt and GRB 021211: a SN/GRB Connection at z = 1

abstract:
  We present spectroscopic and photometric observations of the afterglow of GRB
021211 and the discovery of its associated supernova, SN 2002lt. The spectrum
shows a broad feature (FWHM = 150 A), around 3770 A (in the rest-frame of the
GRB), which we interpret as Ca H+K blueshifted by 14400 km/s. Potential sources
of contamination due to the host galaxy and/or residuals of telluric absorption
have been analyzed and ruled out. Overall, the spectrum shows a suggestive
resemblance with the one of the prototypical type-Ic SN 1994I. This might
indicate that GRBs are produced also by standard type-Ic supernovae.


title: Neutron Star Kicks from Asymmetric Collapse

abstract:
  Many neutron stars are observed to be moving with spatial velocities, in
excess of 500km/s. A number of mechanisms have been proposed to give neutron
stars these high velocities. One of the leading classes of models proposed
invokes asymmetries in the core of a massive star just prior to collapse. These
asymmetries grow during the collapse, causing the resultant supernova to also
be asymmetric. As the ejecta is launched, it pushes off (or ``kicks'') the
newly formed neutron star. This paper presents the first 3-dimensional
supernova simulations of this process. The ejecta is not the only matter that
kicks the newly-formed neutron star. Neutrinos also carry away momentum and the
asymmetric collapse leads also to asymmetries in the neutrinos. However, the
neutrino asymmetries tend to damp out the neutron star motions and even the
most extreme asymmetric collapses presented here do not produce final neutron
star velocities above 200km/s.


title:
XMM-Newton and Chandra observations of three X-ray faint early-type
  galaxies

abstract:
  We present XMM-Newton observations of three X-ray under-luminous elliptical
galaxies, NGC 3585, NGC 4494 and NGC 5322. All three galaxies have relatively
large optical luminosities (log LB=10.35-10.67 solar) but have X-ray
luminosities consistent with emission from discrete sources only. In
conjunction with a Chandra observation of NGC 3585, we analyse the XMM data and
show that the three galaxies are dominated by discrete source emission, but do
possess some X-ray emitting gas. The gas is at relatively low temperatures,
kT=0.25-0.44 keV. All three galaxies show evidence of recent dynamical
disturbance and formation through mergers, including kinematically distinct
cores, young stellar ages, and embedded stellar disks. This leads us to
conclude that the galaxies formed relatively recently and have yet to build up
large X-ray halos. They are likely to be in a developmental phase where the
X-ray gas has a very low density, making it undetectable outside the galaxy
core. However, if the gas is a product of stellar mass loss, as seems most
probable, we would expect to observe supersolar metal abundances. While
abundance is not well constrained by the data, we find best fit abundances <0.1
solar for single-temperature models, and it seems unlikely that we could
underestimate the metallicity by such a large factor.


title:
Modeling an X-ray Flare on Proxima Centauri: evidence of two flaring
  loop components and of two heating mechanisms at work

abstract:
  We model in detail a flare observed on Proxima Centauri with the EPIC-PN on
board XMM-Newton at high statistics and high time resolution and coverage.
Time-dependent hydrodynamic loop modeling is used to describe the rise and peak
of the light curve, and a large fraction of the decay, including its change of
slope and a secondary maximum, over a duration of more than 2 hours. The light
curve, the emission measure and the temperature derived from the data allow us
to constrain the loop morphology and the heating function and to show that this
flare can be described with two components: a major one triggered by an intense
heat pulse injected in a single flaring loop with half-length ~1.0 10^{10} cm,
the other one by less intense heat pulses released after about 1/2 hour since
the first one in related loop systems, probably arcades, with the same
half-length. The heat functions of the two loop systems appear be very similar:
an intense pulse located at the loop footpoints followed by a low gradual decay
distributed in corona. The latter result and the similarity to at least one
solar event (the Bastille Day flare in 2000) indicate that this pattern may be
common to solar and stellar flares, in wide generality.


title: Minor-axis velocity gradients in disk galaxies

abstract:
  We present the ionized-gas kinematics and photometry of a sample of 4 spiral
galaxies which are characterized by a zero-velocity plateau along the major
axis and a velocity gradient along the minor axis, respectively. By combining
these new kinematical data with those available in the literature for the
ionized-gas component of the S0s and spirals listed in the Revised Shapley-Ames
Catalog of Bright Galaxies we realized that about 50% of unbarred galaxies show
a remarkable gas velocity gradient along the optical minor axis. This fraction
rises to about 60% if we include unbarred galaxies with an irregular velocity
profile along the minor axis. This phenomenon is observed all along the Hubble
sequence of disk galaxies, and it is particularly frequent in early-type
spirals. Since minor-axis velocity gradients are unexpected if the gas is
moving onto circular orbits in a disk coplanar to the stellar one, we conclude
that non-circular and off-plane gas motions are not rare in the inner regions
of disk galaxies.


title:
The Canada-UK Deep Submillimetre Survey VIII: Source Identifications in
  the 3-hour field

abstract:
  We present optical, near-infrared and radio observations of the 3-hour field
of the Canada-UK Deep Submillimetre Survey. Of the 27 submillimetre sources in
the field, nine have secure identifications with either a radio source or a
near-IR source. We show that the percentage of sources with secure
identifications in the CUDSS is consistent with that found for the bright `8
mJy' submillimetre survey, once allowance is made for the different
submillimetre and radio flux limits. Of the 14 secure identifications in the
two CUDSS fields, eight are VROs or EROs, five have colours typical of normal
galaxies, and one is a radio source which has not yet been detected at
optical/near-IR wavelengths. Eleven of the identifications have optical/near-IR
structures which are either disturbed or have some peculiarity which suggests
that the host galaxy is part of an interacting system. One difference between
the CUDSS results and the results from the 8-mJy survey is the large number of
low-redshift objects in the CUDSS; we give several arguments why these are
genuine low-redshift submillimetre sources rather than being gravitational
lenses which are gravitationally amplifying a high-$z$ submillimetre source. We
construct a $K-z$ diagram for various classes of high-redshift galaxy and show
that the SCUBA galaxies are on average less luminous than classical radio
galaxies, but are very similar in both their optical/IR luminosities and their
colours to the host galaxies of the radio sources detected in $\mu$Jy radio
surveys.


title:
Search for alpha variation in UVES spectra: Analysis of C IV and Si IV
  doublets towards QSO 1101-264

abstract:
  Motivated by previous studies of QSO spectra that reported a variation of the
fine structure constant alpha, a search for C IV and Si IV doublets was
conducted in the absorption spectrum toward QSO 1101-264, obtained by VLT-UVES
during the Science Verification. Seven C IV and two Si IV systems were
identified and accurate measurements of wavelengths over the redshift range
1.1862 < z < 1.8377 were performed. After a careful selection of pairs of
lines, the "Alkali Doublet" method with a derived analitical expression for the
error analysis was applied to compute the alpha variation. The result according
in magnitud order with previous doublets measurements, corresponds to one Si IV
system: Delta alpha/alpha = (- 3.09 +/- 8.46) x 10^(-5).


title: Is the soft excess in AGN real?

abstract:
  We systematically analyse all publicly available XMM-Newton spectra of
radio-quiet PG quasars. The soft X-ray excess in these objects is well modelled
by an additional, cool, Compton scattering region. However, the remarkably
constant temperature derived for this component over the whole sample requires
a puzzling fine tuning of the parameters. Instead, we propose that the soft
excess is an artifact of strong, relativistically smeared, partially ionized
absorption. The strong jump in opacity at ~0.7 keV from OVII, OVIII and iron
can lead to an apparent soft excess below this energy, which is trivially
constant since it depends on atomic processes. This can have a dramatic effect
on the derived spectrum, which has implications for fitting the relativistic
smearing of the reflected iron line emission from the disc.


title: Gamma Ray Pulsars: Multiwavelength Observations

abstract:
  High-energy gamma rays are a valuable tool for studying particle acceleration
and radiation in the magnetospheres of energetic pulsars. The seven or more
pulsars seen by instruments on the Compton Gamma Ray Observatory (CGRO) show
that: the light curves usually have double-peak structures (suggesting a broad
cone of emission); gamma rays are frequently the dominant component of the
radiated power; and all the spectra show evidence of a high-energy turnover.
For all the known gamma-ray pulsars, multiwavelength observations and
theoretical models based on such observations offer the prospect of gaining a
broad understanding of these rotating neutron stars. The Gamma-ray Large Area
Space Telescope (GLAST), now in planning for a launch in 2007, will provide a
major advance in sensitivity, energy range, and sky coverage.


title:
Weak lensing mass reconstruction of the interacting cluster 1E0657-558:
  Direct evidence for the existence of dark matter

abstract:
  We present a weak lensing mass reconstruction of the interacting cluster
1E0657-558 in which we detect both the main cluster and a sub-cluster. The
sub-cluster is identified as a smaller cluster which has just undergone initial
in-fall and pass-through of the primary cluster, and has been previously
identified in both optical surveys and X-ray studies. The X-ray gas has been
separated from the galaxies by ram-pressure stripping during the pass-through.
The detected mass peak is located between the X-ray peak and galaxy
concentration, although the position is consistent with the galaxy centroid
within the errors of the mass reconstruction. We find that the mass peak for
the main cluster is in good spatial agreement with the cluster galaxies and
offset from the X-ray halo at 3.4 sigma significance, and determine that the
mass-to-light ratios of the two components are consistent with those of relaxed
clusters. The observed offsets of the lensing mass peaks from the peaks of the
dominant visible mass component (the X-ray gas) directly demonstrate the
presence, and dominance, of dark matter in this cluster. This proof of the dark
matter existence holds true even under the assumption of modified Newtonian
gravity (MOND); from the observed gravitational shear to optical light ratios
and mass peak - X-ray gas offsets, the dark matter component in a MOND regime
has a total mass which is at least equal to the baryonic mass of the system.


title: Photon mass generation during inflation: de Sitter invariant case

abstract:
  We calculate the one-loop vacuum polarization tensor of scalar
electrodynamics in a locally de Sitter space-time, endowed with a nearly
minimally coupled, light scalar field. We show that the photon dynamics is well
approximated by a (local) Proca Lagrangean. Since the photon mass can be much
larger than the Hubble parameter, the photons may propagate slowly during
inflation. Finally, we briefly discuss magnetic field generation on
cosmological scales, and point out that, while the spectrum of the magnetic
field is identical to that obtained from the massless scalar, B_l ~ B_0/l, the
amplitude B_0 may be significantly enhanced, implying that the seed field bound
for the galactic dynamo can be easily met.


title:
Signatures of Ultra-High Energy Cosmic Ray Composition from Propagation
  of Nuclei in Intergalactic Photon Fields

abstract:
  We present a calculation of nuclei propagation with energies above 1 EeV in
the intergalactic photon field. The calculation is based on a Monte Carlo
approach for the nucleus-photon interaction as well as the intergalactic
magnetic field. We then assume that the Ultra-High Energy Cosmic Rays are
nuclei which are emitted from extra-galactic point sources. Four bumps are
found in the energy spectrum of the UHECR which form clusters in the
distribution of their arrival directions. Based on this calculation, the energy
distribution of the clustered events is discussed.


title:
Effects of Grain Size on the Spectral Energy Distribution of Dusty
  Circumstellar Envelopes

abstract:
  We study the effects of dust grain size on the spectral energy distribution
(SED) of spherical circumstellar envelopes. Based on the self-similarity
relations of dusty SEDs derived by Ivezic & Elitzur (1997), we expect an
approximate invariance of the IR SED for models with different grain sizes.
Approximate invariance follows from the fact that differently sized grains have
similar optical properties at long wavelengths where the dust reprocesses the
starlight. In this paper, we discuss what are the physical requirements on the
model parameters to maintain the approximate invariance of the IR SED. Single
grain size models are studied for a wide range of grain sizes in three optical
depth regimes. In this study, we find limits for the cases where the IR SED is
and is not capable of conveying information about grain sizes, and to what
extent it does so. We find that approximate invariance occurs for a much larger
range of grain sizes than previously believed, and, when approximate invariance
holds, the SED is controlled mainly by one parameter, the reprocessing optical
depth, a quantity that measures the fraction of starlight that is absorbed by
the dust grains. Models with a grain size distribution are studied as well. For
these models, we find that, in many instances, the concept of approximate
invariance may be extended from the IR SED to all wavelengths. This means that,
for a wide range of optical depths, models with different grain size
distributions will produce very similar SEDs and, hence, the reprocessing
optical depth is the only quantity that can be unambiguously obtained from the
SED. The observational consequences of this result are discussed in detail.


title: Gamma-Ray Bursts and Cosmology

abstract:
  The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the
favored beacons for sampling the high redshift Universe. To employ GRBs to
study the cosmic terrain -- e.g., star and galaxy formation history -- GRB
luminosities must be calibrated, and the luminosity function versus redshift
must be measured or inferred. Several nascent relationships between gamma-ray
temporal or spectral indicators and luminosity or total energy have been
reported. These measures promise to further our understanding of GRBs once the
connections between the luminosity indicators and GRB jets and emission
mechanisms are better elucidated. The current distribution of 33 redshifts
determined from host galaxies and afterglows peaks near z ~ 1, whereas for the
full BATSE sample of long bursts, the lag-luminosity relation predicts a broad
peak z ~ 1-4 with a tail to z ~ 20, in rough agreement with theoretical models
based on star formation considerations. For some GRB subclasses and apparently
related phenomena -- short bursts, long-lag bursts, and X-ray flashes -- the
present information on their redshift distributions is sparse or entirely
lacking, and progress is expected in Swift era when prompt alerts become
numerous.


title:
Deep Near-Infrared Imaging of a Field in the Outer Disk of M82 with the
  ALTAIR Adaptive Optics System on Gemini North

abstract:
  Deep H and K' images, recorded with the ALTAIR adaptive optics system and
NIRI imager on Gemini North, are used to probe the red stellar content in a
field with a projected distance of 1 kpc above the disk plane of the starburst
galaxy M82. The data have an angular resolution of 0.08 arcsec FWHM, and
individual AGB and RGB stars are resolved. The AGB extends to at least 1.7 mag
in K above the RGB-tip, which occurs at K = 21.7. The relative numbers of
bright AGB stars and RGB stars are consistent with stellar evolution models,
and one of the brightest AGB stars has an H-K color and K brightness that is
consistent with it being a C star. The brightnesses of the AGB stars suggest
that they formed during intermediate epochs, possibily after the last major
interaction with M81. Therefore, star formation in M82 during intermediate
epochs may not have been restricted to the plane of the disk.


title: How Can The SN-GRB Time Delay Be Measured?

abstract:
  The connection between SNe and GRBs, launched by SN 1998bw/GRB 980425 and
clinched by SN 2003dh/GRB 030329 -- with the two GRBs differing by a factor of
approximately 50000 in luminosity -- so far suggests a rough upper limit of ~
1-2 days for the delay between SN and GRB. Only four SNe have had nonnegligible
coverage in close coincidence with the initial explosion, near the UV shock
breakout: two Type II, and two Type Ic, SN 1999ex and SN 1998bw. For the
latter, only a hint of the minimum between the UV maximum and the radioactivity
bump served to help constrain the interval between SN and GRB. Swift GRB alerts
may provide the opportunity to study many SNe through the UV breakout phase:
GRB 980425 "look alikes" -- apparently nearby, low-luminosity, soft-spectrum,
long-lag GRBs -- accounted for half of BATSE bursts near threshold, and may
dominate the Swift yield near threshold, since it has sensitivity to lower
energies than did BATSE. The SN to GRB delay timescale should be better
constrained by prompt UV/optical observations alerted by these bursts.
Definitive delay measurements may be obtained if long-lag bursters are truly
nearby: The SNe/GRBs could emit gravitational radiation detectable by LIGO-II
if robust non-axisymmetric bar instabilities develop during core collapse,
and/or neutrino emission may be detectable as suggested by Meszaros et al.


title: Probing the Statistics of the Temperature-Density Relation of the IGM

abstract:
  Gravitational instability induces a simple correlation between the large and
small scale fluctuations of the Ly-alpha flux spectrum. However,
non-gravitational processes involved in structure formation and evolution will
alter such a correlation. In this paper we explore how scatter in the
temperature-density relation of the IGM reduces the gravitationally induced
scale-scale correlation. By examining whether or not observations of the
correlation are close to that predicted by pure gravity, this puts constraints
on the scatter in the temperature-density relation and in turn on any physical
process which would lead to scatter, e.g. strong fluctuations in the UV
background or radiative transfer effects. By applying this method to high
resolution Keck spectra of Q 1422+231 and HS 1946+7658, we find the predicted
correlation signal induced by gravity, and the diminishing of this correlation
signal at small scales. This suggests extra physics affects the small-scale
structure of the forest, and we can constrain the scatter in the
temperature-density relation to a conservative 20% upper limit. A crude model
suggests, if there is any spatial correlation of temperature, the coherence
length scale must be smaller than ~ 0.3/h Mpc to be consistent with the Keck
data.


title: SDSS Quasars and Dust Reddening

abstract:
  The Sloan Digital Sky Survey can be used to detect and characterize red and
reddened quasars. In Richards et al. (2003), we showed that 6% of SDSS quasars
have red colors consistent with significant dust reddening by an extinction
curve similar to that of the Small Magellanic Cloud (SMC). We estimate that a
further 10% of the luminous quasar population is missing from our
magnitude-limited SDSS sample. More recent work (Hopkins et al., in
preparation) confirms the conclusion that dust reddening is the primary
explanation for SDSS quasars in the red tail of the color distribution. Fitting
orthogonal first- and second-order polynomials to SDSS quasar photometry
measures the slope and curvature of each object's UV/optical spectrum. The
slope vs. curvature distribution is elongated along the axis predicted for
SMC-like reddening, while the axes predicted for LMC- or MW-like reddening
provide significantly poorer fits. Extension to longer wavelengths using a
smaller sample of SDSS/2MASS matches confirms this result at high significance.


title: Jet-Induced Star Formation

abstract:
  Jets from radio galaxies can have dramatic effects on the medium through
which they propagate. We review observational evidence for jet-induced star
formation in low ('FR-I') and high ('FR-II') luminosity radio galaxies, at low
and high redshifts respectively. We then discuss numerical simulations which
are aimed to explain a jet-induced starburst ('Minkowski's Object') in the
nearby FR-I type radio galaxy NGC 541. We conclude that jets can induce star
formation in moderately dense (10 cm-3), warm (10,000 K) gas; that this may be
more common in the dense environments of forming, active galaxies; and that
this may provide a mechanism for 'positive' feedback from AGN in the galaxy
formation process.


title:
Measurement of Cosmic Shear with the Space Telescope Imaging
  Spectrograph

abstract:
  Weak lensing by large-scale structure allows a direct measure of the dark
matter distribution. We have used parallel images taken with the Space
Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope to measure
weak lensing, or cosmic shear. We measure the shapes of 26036 galaxies in 1292
STIS fields and measure the shear variance at a scale of 0.51 arcminutes. The
charge transfer efficiency (CTE) of STIS has degraded over time and introduces
a spurious ellipticity into galaxy shapes during the readout process. We
correct for this effect as a function of signal to noise and CCD position. We
further show that the detected cosmic shear signal is nearly constant in time
over the approximately four years of observation. We detect cosmic shear at the
5.1 sigma level, and our measurement of the shear variance is consistent with
theoretical predictions in a LambdaCDM universe. This provides a measure of the
normalization of the mass power spectrum sigma_8=(1.02 +- 0.16)
(0.3/Omega_m)^{0.46} (0.21/Gamma)^{0.18}$. The one-sigma error includes noise,
cosmic variance, systematics and the redshift uncertainty of the source
galaxies. This is consistent with previous cosmic shear measurements, but tends
to favor those with a high value of sigma_8. It is also consistent with the
recent determination of sigma_8 from the Wilkinson Microwave Anisotropy Probe
(WMAP) experiment.


title: Constraining Cut-off Physics in the Cosmic Microwave Background

abstract:
  We investigate the ability to constrain oscillatory features in the
primordial power spectrum using current and future cosmic microwave background
observations. In particular, we study the observability of an oscillation
arising from imprints of physics at the cut-off energy scale. We perform a
likelihood analysis on the WMAP data set, and find that the current data set
constrains the amplitude of the oscillations to be less than 0.77 at 2-sigma,
consistent with a power spectrum without oscillations. In addition, we
investigate the fundamental limitations in the measurement of oscillation
parameters by studying the constraints from a cosmic variance limited
experiment. We find that such an experiment is capable of constraining the
amplitude of such oscillations to be below 0.005, implying that reasonable
models with cut-off energy scales Lambda>200 H_infl are unobservable through
the microwave background.


title: S Ori 70: Just a Foreground Field Brown Dwarf?

abstract:
  We examine recent claims that the T-type brown dwarf S Ori 053810.1-023626 (S
Ori 70) is a spectroscopically verified low mass (3$^{+5}_{-1}$ M$_{Jup}$)
member of the 1--8 Myr $\sigma$ Orionis cluster. Comparative arguments by
Mart{\'{i}}n & Zapatero Osorio asserting that S Ori 70 exhibits low surface
gravity spectral features indicative of youth and low mass are invalidated by
the fact that their comparison object was not the field T dwarf 2MASS
0559$-$1404 but rather a nearby background star. Instead, we find that the
1--2.5 $\micron$ spectra of S Ori 70 are well-matched to older (age $\sim$ few
Gyr) field T6--T7 dwarfs. Moreover, we find that spectral model fits to
late-type field T dwarf spectra tend to yield low surface gravities ($\log{g}$
= 3.0--3.5), and thus young ages ($\lesssim$ 5 Myr) and low masses ($\lesssim$
3 M$_{Jup}$), inconsistent with expected and/or empirical values. Finally, we
show that the identification of one T dwarf in the field imaged by Zapatero
Osorio et al. is statistically consistent with the expected foreground
contamination. Based on the re-examined evidence, we conclude that S Ori 70 may
simply be an old, massive (30--60 M$_{Jup}$) field brown dwarf lying in the
foreground of the $\sigma$ Orionis cluster. This interpretation should be
considered before presuming the existence of so-called ``cluster planets.''


title: Probing Primordial Non-Gaussianity with Large-Scale Structure

abstract:
  We consider primordial non-Gaussianity due to quadratic corrections in the
gravitational potential parametrized by a non-linear coupling parameter fnl. We
study constraints on fnl from measurements of the galaxy bispectrum in redshift
surveys. Using estimates for idealized survey geometries of the 2dF and SDSS
surveys and realistic ones from SDSS mock catalogs, we show that it is possible
to probe |fnl|~100, after marginalization over bias parameters. We apply our
methods to the galaxy bispectrum measured from the PSCz survey, and obtain a
2sigma-constraint |fnl|< 1800. We estimate that an all sky redshift survey up
to z~1 can probe |fnl|~1. We also consider the use of cluster abundance to
constrain fnl and find that in order to be sensitive to |fnl|~100, cluster
masses need to be determined with an accuracy of a few percent, assuming
perfect knowledge of the mass function and cosmological parameters.


title: The Formation and Early Evolution of Protostellar Accretion Disks

abstract:
  Newly formed stars are often observed to possess circumstellar disks, from
which mass continues to be accreted onto the star and fed into outflowing jets,
and which eventually may evolve into dusty debris disks and planetary systems.
Recent modeling developments have made it possible, for the first time, to
study the formation and early evolution of rotationally supported protostellar
disks in the context of a realistic scenario of star formation in weakly
ionized, magnetic, molecular cloud cores. The derived semianalytic solutions
incorporate ambipolar diffusion and magnetic braking and may be extended to
include centrifugally driven disk winds; they can be used to examine the full
range of expected behaviors of real systems and their dependence on physical
parameters.


title:
A Near-Infrared Multiplicity Survey of Class I/Flat-Spectrum Systems in
  Six Nearby Molecular Clouds

abstract:
  We present new near-IR observations of 76 Class I/flat-spectrum objects in
the nearby (d < 320 pc) Perseus, Taurus, Chamaeleon I and II, rho Ophiuchi, and
Serpens dark clouds. These observations are part of a larger systematic
infrared multiplicity survey of self-embedded objects in the nearest dark
clouds. When combined with the results of our previously published
near-infrared multiplicity survey, we find a restricted companion star fraction
of 14/79 (18% +/- 4%) of the sources surveyed to be binary or higher order
multiple systems over a separation range of ~300 - 2000 AU with a magnitude
difference $\Delta$ K <= 4, and with no correction for background contamination
or completeness. This is consistent with the fraction of binary/multiple
systems found among older pre-main-sequence T Tauri stars in each of the
Taurus, rho Ophiuchi, and Chamaeleon star-forming regions over a similar
separation range, as well as the combined companion star fraction for these
regions. However, the companion star fraction for solar-type, and lower mass M
dwarf, main-sequence stars in the solar neighborhood in this separation range
(11% +/- 3%) is approximately one-half that of our sample. Together with
multiplicity statistics derived for previously published samples of Class 0 and
Class I sources, our study suggests that a significant number of
binary/multiple objects may remain to be discovered at smaller separations
among our Class I/flat-spectrum sample and/or most of the evolution of
binary/multiple systems occurs during the Class 0 phase of early stellar
evolution.


title: First Results From Sleuth: The Palomar Planet Finder

abstract:
  We discuss preliminary results from our first search campaign for transiting
planets performed using Sleuth, an automated 10 cm telescope with a 6 degree
square field of view. We monitored a field in Hercules for 40 clear nights
between UT 2003 May 10 and July 01, and obtained an rms precision (per 15-min
average) over the entire data set of better than 1% on the brightest 2026
stars, and better than 1.5% on the brightest 3865 stars. We identified no
strong candidates in the Hercules field. We conducted a blind test of our
ability to recover transiting systems by injecting signals into our data and
measuring the recovery rate as a function of transit depth and orbital period.
About 85% of transit signals with a depth of 0.02 mag were recovered. However,
only 50% of transit signals with a depth of 0.01 mag were recovered. We expect
that the number of stars for which we can search for transiting planets will
increase substantially for our current field in Andromeda, due to the lower
Galactic latitude of the field.


title:
Line formation in solar granulation: IV. [O I], OI and OH lines and the
  photospheric O abundance

abstract:
  The solar photospheric oxygen abundance has been determined from [OI], OI, OH
vibration-rotation and OH pure rotation lines by means of a realistic
time-dependent, 3D, hydrodynamical model of the solar atmosphere. In the case
of the OI lines, 3D non-LTE calculations have been performed, revealing
significant departures from LTE as a result of photon losses in the lines. We
derive a solar oxygen abundance of log O = 8.66 +/- 0.05. All oxygen
diagnostics yield highly consistent abundances, in sharp contrast with the
results of classical 1D model atmospheres. This low value is in good agreement
with measurements of the local interstellar medium and nearby B stars. This low
abundance is also supported by the excellent correspondence between lines of
very different line formation sensitivities, and between the observed and
predicted line shapes and center-to-limb variations. Together with the
corresponding down-ward revisions of the solar carbon, nitrogen and neon
abundances, the resulting significant decrease in solar metal mass fraction to
Z = 0.0126 can, however, potentially spoil the impressive agreement between
predicted and observed sound speed in the solar interior determined from
helioseismology.


title:
Line formation in solar granulation: V. Missing UV-opacity and the
  photospheric Be abundance

abstract:
  The possibility of unaccounted for opacity sources in the UV for late-type
stars has often been invoked to explain discrepancies between predicted and
observed flux distributions and spectral line strengths. Such missing
UV-opacity could among other things have a significant impact on abundance
determination for elements whose only relevant spectral features are accessible
in this wavelength region, such as Be. Here, the study by Balachandran & Bell
(1998) is re-visited in the light of a realistic 3D hydrodynamical solar model
atmosphere and the recently significantly downward revised solar O abundance
obtained with the same model atmosphere. The amount of missing UV-opacity, if
any, is quantified by enforcing that the OH A-X electronic lines around 313 nm
produce the same O abundance as the other available diagnostics: OH
vibration-rotation and pure rotation lines in the IR, the forbidden [OI] 630.0
and 636.3 nm lines and high-excitation, permitted OI lines. This additional
opacity is then applied for the synthesis of the BeII line at 313.0nm to derive
a solar photospheric Be abundance in excellent agreement with the meteoritic
value, thus re-enforcing the conclusions of Balachandran & Bell. The about 50%
extra opacity over accounted for opacity sources can be well explained by
recent calculations by the Iron Project for photo-ionization of FeI.


title: Scaling relations in early-type galaxies belonging to groups

abstract:
  We present a photometric analysis of a large sample of early-type galaxies in
16 nearby groups, imaged with the Wide-Field Camera on the Isaac Newton
Telescope. Using a two-dimensional surface brightness decomposition routine, we
fit Sersic (r^{1/n}) and exponential models to their bulge and disk components
respectively. Dividing the galaxies into three subsamples according to the
X-ray luminosities of their parent groups, we compare their photometric
properties. Galaxies in X-ray luminous groups tend to be larger and more
luminous than those in groups with undetected or low X-ray luminosities, but no
significant differences in n are seen. Both normal and dwarf elliptical
galaxies in the central regions of groups are found to have cuspier profiles
than their counterparts in group outskirts.
  Structural differences between dwarf and normal elliptical galaxies are
apparent in terms of an offset between their ``Photometric Planes'' in the
space of n, r_e and mu_0. Dwarf ellipticals are found to populate a surface,
with remarkably low scatter, in this space with significant curvature, somewhat
similar to the surfaces of constant entropy proposed by Marquez etal (2001).
Normal ellipticals are offset from this distribution in a direction of higher
specific entropy. This may indicate that the two populations are distinguished
by the action of galaxy merging on larger galaxies.


title: Tracing the evolution of massive galaxies up to z \sim 3

abstract:
  A census of massive galaxies at redshift increasingly higher than $z\sim$1
may provide strong constraints on the history of mass assembly and of star
formation. Here we report on the analysis of three galaxies selected in the
Hubble Deep Field South on the basis of their unusually red near-IR color
J-K$\ge$3. These objects result to be massive (M$_{star}\sim
10^{11}$M$_{\odot}$) galaxies at redshift 2.5$<$z$<$3 which cannot follow an
evolution significantly different from passive aging. Thus, their counterpart
can be found among the EROs (i.e., R-K>5) at 1$<$z$<$1.5, and among the local
massive old early-type galaxies at $z=0$. In order to find their counterpart
also at the intermediate redshift z$\sim$2, we present a new color selection
criterion (J-K$<$3 and I-H$>$4) on the basis of which we identified 4 massive
evolved galaxies at 1.5$<z<$2.5. We show an example of a passive evolution
scenario in which three massive galaxies at different redshift are apparently
those we expect from a massive galaxy fully assembled at z$\sim$3 which evolves
passively in time down to $z=0$.


title: Short-Bright GRBs: spectral properties

abstract:
  We study the spectra of short-bright GRBs detected by BATSE and compare them
with the average and time resolved spectral properties of long-bright bursts.
We confirm that short events are harder than long bursts, as already found from
the comparison of their (fluence) hardness ratio, but we find that this
difference is mainly due to a harder low energy spectral component present in
short bursts, rather than to a (marginally) different peak energy. Moreover, we
find that short GRBs are similar to the first 1 sec emission of long bursts.
The comparison of the energetic of short and long bursts also suggests that
short GRBs do not obey the peak energy--equivalent isotropic energy correlation
recently proposed for long events, implying that short GRBs emit lower energy
than long ones. Nonetheless, short bursts seem to emit a luminosity similar to
long GRBs and under such hypothesis their redshift distribution appears
consistent with that observed for long events. These findings might suggest the
presence of a common mechanism at the beginning of short and long bursts which
operates on different timescales in the these two classes.


title: Astrophysics of the Knee in the Cosmic Ray Energy Spectrum

abstract:
  A brief review is given on the astrophysics of cosmic rays in the PeV primary
energy range, i.e. the region of the knee.


title: J1432+158: the most distant giant quasar

abstract:
  We present low-frequency, GMRT (Giant Metrewave Radio Telescope) observations
at 333 and 617 MHz of the most-distant giant quasar, J1432+158, which is at a
redshift of 1.005. The radio source has a total angular extent of 168 arcsec,
corresponding to a projected linear size of 1.35 Mpc. This makes it presently
the largest single object observed beyond a redshift of one. The objectives of
the GMRT observations were to investigate the possibility of detecting a bridge
of emission at low frequencies, which may be suppressed due to inverse-Compton
losses against the cosmic microwave background radiation. We detect a jet-like
structure connecting the core to the western hotspot, while the eastern hotspot
is found to be largely tail-less with no significant bridge emission. The
estimated life-time for the radiating electrons in the tail of the western lobe
appears smaller than the travel time of the radiating particles from the
hotspot, suggesting either in-situ acceleration or dissipation of energy by the
jet at this location. The pressure of the intergalactic medium at $z\sim1$
estimated from the minimum energy density calculations appears to be marginally
lower than the value extrapolated from nearby giant radio galaxies.


title:
Flares from small to large: X-ray spectroscopy of Proxima Centauri with
  XMM-Newton

abstract:
  (Abridged) We report results from a comprehensive study of the nearby M dwarf
Proxima Centauri with the XMM-Newton satellite. We find strongly variable
coronal X-ray emission, with flares ranging over a factor of 100 in peak flux.
The low-level emission is found to be continuously variable. Several weak
flares are characteristically preceded by an optical burst, compatible with
predictions from standard solar flare models. We propose that the U band bursts
are proxies for the elusive stellar non-thermal hard X-ray bursts suggested
from solar observations. A very large X-ray flare was observed in its entirety,
with a peak luminosity of 3.9E28 erg/s [0.15-10 keV] and a total X-ray energy
of 1.5E32 erg. This flare has allowed to measure significant density variations
from X-ray spectroscopy of the OVII He-like triplet; we find peak densities
reaching up to 4E11 cm^-3 for plasma of about 1-5 MK. Abundance ratios show
little variability in time, with a tendency of elements with a high first
ionization potential to be overabundant relative to solar photospheric values.
We do not find significant effects due to opacity during the flare, indicating
that large opacity increases are not the rule even in extreme flares. We model
the large flare in terms of an analytic 2-Ribbon flare model and find that the
flaring loop system should have large characteristic sizes (~1R*). These
results are supported by full hydrodynamic simulations. Comparing the large
flare to flares of similar size occurring much more frequently on more active
stars, we propose that the X-ray properties of active stars are a consequence
of superimposed flares such as the example analyzed in this paper. Such a model
also explains why, during episodes of low-level emission, more active stars
show hotter plasma than less active stars.


title:
IZw1 observed with XMM-Newton: Low-energy spectral complexity, iron
  lines, and hard X-ray flares

abstract:
  We present a 20 ks XMM-Newton observation of the prototypical Narrow-Line
Seyfert 1 galaxy IZw1. The best-fit model to the data is a double blackbody
plus a dominant power-law, on which complex soft absorption (possibly a blended
edge or absorption lines) and/or OVII emission are superimposed, as well as
strong Fe Kalpha emission. The iron feature in the high-energy spectra appears
broad; however, on close examination of the EPIC pn data, there exists the
possibility that the broad emission feature can be attributed to a neutral Fe
Kalpha line in addition to a blend of He- and H-like Fe Kalpha lines. The light
curve shows a strong, hard X-ray flare concentrated in the 3-12 keV band. The
flare appears to induce spectral variability, showing spectral hardening to be
occuring as the flare intensifies. A detailed examination suggests that the
spectral variability is most likely due to an increase in the 3-12 keV flux
relative to the soft flux during the flare. A difference spectrum and complete
modelling of the flare and non-flare spectra show intrinsic changes only in the
normalisation of the continuum components and not in their shape parameters.
The timing results are consistent with the flare originating in the accretion
disc corona. The iron emission line(s) do not appear to respond to changes in
the continuum flux during the flare; the iron lines are stronger in equivalent
width during the low-flux (non-flare) states, and weaker during the flare.


title: Observations of SNR G328.4+0.2 at 19 GHz

abstract:
  We report on the first polarimetric observations at 19 GHz made with the
upgraded Australia Telescope Compact Array. Observations were made of the
Galactic supernova remnant (SNR) G328.8+0.2. We find the SNR has circular
morphology with a strong central bar, similar to that seen at lower
frequencies. The SNR has high linear polarization throughout, with fractional
polarization in the bar up to 50 per cent. The orientation of the magnetic
field lines follow the filamentary structure of the SNR. The magnetic field at
the edge of the SNR is generally toroidal, interspersed with radial fingers,
likely caused by Rayleigh-Taylor instabilities. Although the SNR has been
identified as Crab-like, we prefer an interpretation in which the bar is a
pulsar powered wind nebula with the rest of the SNR consisting of the shell.
The proposed pulsar parameters make the SNR / pulsar system more like SNR
G11.2--0.3 than the Crab Nebula.