title:
Color-redshift Relations and Photometric Redshift Estimations of Quasars
  in Large Sky Surveys

abstract:
  With a recently constructed composite quasar spectrum and the \chi^2
minimization technique, we demonstrated a general method to estimate the
photometric redshifts of a large sample of quasars by deriving the theoretical
color-redshift relations and comparing the theoretical colors with the observed
ones. We estimated the photometric redshifts from the 5-band SDSS photometric
data of 18678 quasars in the first major data release of SDSS and compare them
with the spectroscopic redshifts. The redshift difference is smaller than 0.1
for 47% of quasars and 0.2 for 68 % of them. Based on the calculation of the
theoretical color-color diagrams of stars, galaxies and quasars in both the
SDSS and BATC photometric systems, we expected that with the BATC system of 15
intermediate filters we would be able to select candidates of high redshift
quasars more efficiently than in the SDSS, provided the BATC survey could
detect objects with magnitude fainter than 21.


title: XMM-Newton RGS spectroscopy of LMC X-3

abstract:
  We present soft X-ray spectroscopy of the black hole binary LMC X-3 from the
XMM-Newton Reflection Grating Spectrometer. The observations span the full
range of spectral states seen in LMC X-3. The spectra are completely dominated
by continuum emission, and the neutral absorbing column measured from the O I
edge (NH = 3.8 +0.8 -0.7 10^20 cm^-2) is consistent with the Galactic
interstellar column density towards LMC X-3. We find no evidence for
variability of the neutral absorbing column. We also constrain the ionized
column density using the upper limits to the equivalent width of the O II - O
VIII K-shell resonance lines: we find that the equivalent hydrogen column
density of gas in which O is partially ionized is < 8 10^20 cm^-2. From this
upper limit we can rule out a line driven stellar wind as the power source for
the X-ray emission of LMC X-3 except when it is faint. At wavelengths longward
of the peak emission the spectral shape is well described by a
multi-temperature disk-blackbody spectrum; the powerlaw component which
dominates at shorter wavelengths does not continue longward of the
disk-blackbody peak. This implies that the multi-temperature disk-blackbody
component supplies the seed photons which are Compton upscattered in the hot
corona, consistent with the standard paradigm for black hole X-ray binary
spectral states.


title:
On characterising the variability properties of X-ray light curves from
  active galaxies

abstract:
  We review some practical aspects of measuring the amplitude of variability in
`red noise' light curves typical of those from Active Galactic Nuclei (AGN).
The quantities commonly used to estimate the variability amplitude in AGN light
curves, such as the fractional rms variability amplitude, F_var, and excess
variance, sigma_XS^2, are examined. Their statistical properties, relationship
to the power spectrum, and uses for investigating the nature of the variability
processes are discussed. We demonstrate that sigma_XS^2 (or similarly F_var)
shows large changes from one part of the light curve to the next, even when the
variability is produced by a stationary process. This limits the usefulness of
these estimators for quantifying differences in variability amplitude between
different sources or from epoch to epoch in one source. Some examples of the
expected scatter in the variance are tabulated for various typical power
spectral shapes, based on Monte Carlo simulations. The excess variance can be
useful for comparing the variability amplitudes of light curves in different
energy bands from the same observation. Monte Carlo simulations are used to
derive a description of the uncertainty in the amplitude expected between
different energy bands (due to measurement errors). Finally, these estimators
are used to demonstrate some variability properties of the bright Seyfert 1
galaxy Markarian 766. The source is found to show a strong, linear correlation
between rms amplitude and flux, and to show significant spectral variability.


title:
Hydrogen Spectra, Molecular Association and Orbital Radii in the Solar
  System

abstract:
  A relationship between the average orbital radii of the planets and their
satellites in the solar system and the spectra of atomic and molecular hydrogen
is identified and investigated. In this model, stimulated radiative association
resonances develop early on in the disk of the protosun that cause the disk to
cool at only certain radii, with each radius depending on a specific photon
energy in the atomic hydrogen spectrum. The planets then evolve from the
relatively cool rings that are formed. Similar activity occurs in the formation
of the satellite systems of the giant planets. The present investigation deals
with the mechanism that generates rings from which the planets are formed. It
does not deal with the evolution of the rings into planets. Many
characteristics of the solar system are explained including the sizes of the
orbital radii of the planets and their satellites, the tilt of Uranus's axis,
the positions of the asteroid and Kuiper belts, the source of the scattered
Kuiper belt objects, the positions of Saturn's main rings and the rings of
Uranus, Jupiter, and Neptune. It also shows that a commonality exists in the
structures of the solar system and the planetary systems that can be attributed
to the common process that initiated their evolution.


title: Quantitative Interpretation of Quasar Microlensing Light Curves

abstract:
  We develop a general method for analyzing the light curves of microlensed
quasars and apply it to the OGLE light curves of the four-image lens
Q2237+0305. We simultaneously estimate the effective source velocity, the
average stellar mass, the stellar mass function, and the size and structure of
the quasar accretion disk. The light curves imply an effective source plane
velocity of 10200 km/s < v_e h / sqrt(<M>) < 39600 km/s (68% confidence). Given
an independent estimate for the source velocity, found by combining estimates
for the peculiar velocity of the lens galaxy with its measured stellar velocity
dispersion, we obtain a mean stellar mass of <M>=0.037h^2 solar masses
(0.0059h^2 < <M>/Msun < 0.20h^2). We were unable to distinguish a Salpeter mass
function from one in which all stars had the same mass, but we do find a strong
lower bound of 50% on the fraction of the surface mass density represented by
the microlenses. Our models favor a standard thin accretion disk model as the
source structure over a simple Gaussian source. For a face-on, thin disk
radiating as a black body with temperature profile T_s ~ R^(-3/4), the radius
r_s where the temperature matches the filter pass band (2000 Angstroms or
T_s(r_s)=70000K) is (1.4 x 10^15)/h cm < r_s < (4.5 x 10^15)/h cm. The flux
predicted by the disk model agrees with the observed flux of the quasar, so
non-thermal or optically thin emission processes are not required. From the
disk structure we estimate a black hole mass of M_BH = (1.1_(-0.7)^(+1.4) x
10^9) h^(-3/2) (L/L_E)^(-1/2) solar masses, consistent with the mass estimated
under the assumption that the quasar is radiating at the Eddington luminosity
(L/L_E=1).


title: Salvaging 1/R gravity models

abstract:
  This paper has been withdrawn by the author. It was argued that increasing F'
would reduce the strength of the scalar coupling to matter. This argument
failed to realize that the gravitational coupling to matter is controlled by
the same power of F', hence the scalar always couples with the same strength as
gravity.


title:
Observations of the SW Sextantis star DW Ursae Majoris with the Far
  Ultraviolet Spectroscopic Explorer

abstract:
  We present an analysis of the first far-ultraviolet observations of the SW
Sextantis-type cataclysmic variable DW Ursae Majoris, obtained in November 2001
with the Far Ultraviolet Spectroscopic Explorer. The time-averaged spectrum of
DW UMa shows a rich assortment of emission lines (plus some contamination from
interstellar absorption lines including molecular hydrogen). Accretion disk
model spectra do not provide an adequate fit to the far-ultraviolet spectrum of
DW UMa. We constructed a light curve by summing far-ultraviolet spectra
extracted in 60-sec bins; this shows a modulation on the orbital period, with a
maximum near photometric phase 0.93 and a minimum half an orbit later. No other
periodic variability was found in the light curve data. We also extracted
spectra in bins spanning 0.1 in orbital phase; these show substantial variation
in the profile shapes and velocity shifts of the emission lines during an
orbital cycle of DW UMa. Finally, we discuss possible physical models that can
qualitatively account for the observed far-ultraviolet behavior of DW UMa, in
the context of recent observational evidence for the presence of a
self-occulting disk in DW UMa and the possibility that the SW Sex stars may be
the intermediate polars with the highest mass transfer rates and/or weakest
magnetic fields.


title: Models for Type I X-Ray Bursts with Improved Nuclear Physics

abstract:
  Multi-zone models of Type I X-ray bursts are presented that use an adaptive
nuclear reaction network of unprecedented size, up to 1300 isotopes. Sequences
of up to 15 bursts are followed for two choices of accretion rate and
metallicity. At 0.1 Eddington (and 0.02 Eddington for low metallicity),
combined hydrogen-helium flashes occur. The rise times, shapes, and tails of
these light curves are sensitive to the efficiency of nuclear burning at
various waiting points along the rp-process path and these sensitivities are
explored. The bursts show "compositional inertia", in that their properties
depend on the fact that accretion occurs onto the ashes of previous bursts
which contain left-over hydrogen, helium and CNO nuclei. This acts to reduce
the sensitivity of burst properties to metallicity. For the accretion rates
studied, only the first anomalous burst in one model produces nuclei as heavy
as A=100, other bursts make chiefly nuclei with A~64. The amount of carbon
remaining after hydrogen-helium bursts is typically <1% by mass, and decreases
further as the ashes are periodically heated by subsequent bursts. At the lower
accretion rate of 0.02 Eddington and solar metallicity, the bursts ignite in a
hydrogen-free helium layer. At the base of this layer, up to 90% of the helium
has already burned to carbon prior to the unstable ignition. These
helium-ignited bursts have briefer, brighter light curves with shorter tails,
very rapid rise times (<0.1 s), and ashes lighter than the iron group.


title: High Redshift Supermassive Black Holes: X-ray observations

abstract:
  The spectrum of the hard X-ray background records the history of accretion
processes integrated over the cosmic time. Several observational and
theoretical evidences indicate that a significant fraction of the energy
density is obscured by large columns of gas and dust. X-ray surveys are the
most efficient way to trace accretion onto supermassive black holes, since
obscured, accreting sources are more difficult to select at all other
wavelengths. The current status of hard X-ray surveys after the recent
observations carried out with Chandra and XMM-Newton satellites is reviewed
along with the results of extensive follow-up multiwavelength observations. In
particular recent results concerning the physical and evolutive properties of
the supermassive black holes hosted by X-ray selected Active Galactic Nuclei at
high redshifts will be discussed.


title: The $\Lambda{\rm CDM}$ Limit of the Generalized Chaplygin Gas Scenario

abstract:
  We explicitly demonstrate that, contrary to recent claims, the dynamics of a
generalized Chaplygin gas model with an equation of state $p=-C$ (where $C$ is
a positive constant) is equivalent to that of a standard $\Lambda$CDM model to
first order in the metric perturbations. We further argue that the analogy
between the two models goes well beyond linear theory and conclude that they
cannot be distinguished based on gravity alone.


title:
Magnetohydrodynamic Jump Conditions for Oblique Relativistic Shocks with
  Gyrotropic Pressure

abstract:
  Shock jump conditions are obtained for steady-state, plane shocks with
oblique magnetic fields and arbitrary flow speeds. For ultrarelativistic and
nonrelativistic shocks, the jump conditions may be solved analytically. For
mildly relativistic shocks, analytic solutions are obtained for isotropic
pressure using an approximation for the adiabatic index that is valid in high
sonic Mach number cases. In the more general case of gyrotropic pressure, the
jump conditions cannot be solved analytically without additional assumptions,
and the effects of gyrotropic pressure are investigated by parameterizing the
distribution of pressure parallel and perpendicular to the magnetic field. Our
numerical solutions reveal that relatively small departures from isotropy
(e.g., about 20%) produce significant changes in the shock compression ratio,
r, at all shock Lorentz factors, including ultrarelativistic ones, where an
analytic solution with gyrotropic pressure is obtained. In particular, either
dynamically important fields or significant pressure anisotropies can incur
marked departures from the canonical gas dynamic value of r=3 for a shocked
ultrarelativistic flow and this may impact models of particle acceleration in
gamma-ray bursts and other environments where relativistic shocks are inferred.
The jump conditions presented apply directly to test-particle acceleration, and
will facilitate future self-consistent numerical modeling of particle
acceleration at oblique, relativistic shocks.


title:
Meeting the Cool New Neighbors V: A 2MASS-Selected Sample of Ultracool
  Dwarfs

abstract:
  We present initial results of our effort to create a statistically robust,
volume-limited sample of ultracool dwarfs from the 2MASS Second Incremental
Data Release. We are engaged in a multifaceted search for nearby late-type
dwarfs and this is the first installment of our search using purely photometric
selection. The goal of this work is a determination of the low-mass star and
brown dwarf luminosity function in the infrared. Here, we outline the
construction of the sample, dubbed 2MU2, and present our first results,
including the discovery of 186 M7--L6 dwarfs--47 of these are likely to be
within 20 pc of the Sun. These results represent 66% of the ultracool
candidates in our sample yet constitute an 127% increase in the number of
ultracool dwarfs known within the volume searched (covering 40% of the sky out
to 20 pc). In addition, we have identified 10 M4--M6.5 objects that are likely
to be within 20 pc (or within 1$\sigma$). Finally, based on these initial data,
we present a preliminary luminosity function and discuss several interesting
features of the partial sample presented here. Once our sample is complete, we
will use our measured luminosity function to constrain the mass function of
low-mass stars and brown dwarfs.


title: Photon Orbital Angular Momentum in Astrophysics

abstract:
  Astronomical observations of the orbital angular momentum of photons, a
property of electromagnetic radiation that has come to the fore in recent
years, have apparently never been attempted. Here, I show that measurements of
this property of photons have a number of astrophysical applications.


title: Using Optical and Near-IR Photometry to Test MACHO Lens Candidates

abstract:
  We obtained new VLT/ISAAC H-band observations for five MACHO LMC source stars
and adjacent LMC field regions. After combining our near-IR photometry with
HST/PC BVRI optical photometry, we compared the MACHO objects to the adjacent
field stars in a variety of color-magnitude and color-color diagrams. These
diagnostic diagrams were chosen to be sensitive to our hypothesis that at least
some of the MACHO lenses were foreground Galactic disk or thick disk M dwarfs.
For the five lensed objects we studied, our hypothesis could be ruled out for
main sequence lens masses >= 0.1 Mo for distances out to 4 kpc. On the other
hand, the fact that LMC-MACHO-5, an object not in our study, has been recently
found to have just such a foreground lens, highlights that the remainder of the
LMC MACHO objects should be searched for the signature of their lenses using
our photometric technique, or via near-IR spectroscopy. We also constructed
diagnostic color-color diagrams sensitive to determining reddening for the
individual MACHO source stars and found that these five objects did not show
evidence for significant additional reddening. At least these five MACHO
objects are thus also inconsistent with the LMC self-lensing hypothesis.


title: A parsec-scale flow associated with the IRAS 16547-4247 radio jet

abstract:
  IRAS 16547-4247 is the most luminous (6.2 x 10^4 Lsun) embedded young stellar
object known to harbor a thermal radio jet. We report the discovery using
VLT-ISAAC of a chain of H_2 2.12 um emission knots that trace a collimated flow
extending over 1.5 pc. The alignment of the H_2 flow and the central location
of the radio jet implies that these phenomena are intimately linked. We have
also detected using TIMMI2 an isolated, unresolved 12 um infrared source
towards the radio jet . Our findings affirm that IRAS 16547-4247 is excited by
a single O-type star that is driving a collimated jet. We argue that the
accretion mechanism which produces jets in low-mass star formation also
operates in the higher mass regime.


title: The AGILE Archive and Data Processing at the ASI Science Data Center

abstract:
  AGILE (Astro-rivelatore Gamma ad Immagini LEggero) is a Small Scientific
Mission of the Italian Space Agency (ASI) with a Science Program open to the
national and international community. Its main goal is to develop and operate a
scientific satellite devoted to Gamma-ray (30 MeV - 50 GeV) and hard X-ray (10
- 40 keV) Astrophysics during the years 2005 - 2007. ASI plans to handle AGILE
data through the ASI Science Data Center in collaboration with the AGILE Team.


title:
Disk and Halo Wide Binaries from the Revised Luyten Catalog: Probes of
  Star Formation and MACHO Dark Matter

abstract:
  We present a catalog of 1147 candidate common proper motion binaries selected
from the revised New Luyten Two-Tenths Catalog. Among these, we identify 999
genuine physical pairs using the measured proper-motion difference and the
relative positions of each binary's components on a reduced proper-motion (RPM)
diagram. The RPM positions also serve to classify them as either disk
main-sequence (801), halo subdwarf (116), or pairs containing at least one
white dwarf (82). The disk and halo samples are complete to separations of
\theta=500" and \theta=900", which correspond to ~0.1 pc and ~1 pc,
respectively. At wide separations, both distributions are well described by
single power laws, dN/d\theta ~ \theta^{-\alpha}: \alpha=1.67+-0.07 for the
disk and \alpha=1.55+-0.10 for the halo. The fact that these distributions have
similar slopes (and similar normalizations as well) argues for similarity of
the star-formation conditions of these two populations. The fact that the halo
binaries obey a single power law out to ~1 pc permits strong constraints on
halo dark-matter candidates. At somewhat closer separations (10"<\theta<25"),
the disk distribution shows a pronounced flattening, which is detected at very
high statistical significance and is not due to any obvious systematic effect.
We also present a list of 11 previously unknown halo stars with parallaxes that
are recognized here as companions of Hipparcos stars.


title:
Photometry and Spectroscopy of GRB 030329 and Its Associated Supernova
  2003dh: The First Two Months

abstract:
  We present extensive optical and infrared photometry of the afterglow of
gamma-ray burst (GRB) 030329 and its associated supernova (SN) 2003dh over the
first two months after detection (2003 March 30-May 29 UT). Optical
spectroscopy from a variety of telescopes is shown and, when combined with the
photometry, allows an unambiguous separation between the afterglow and
supernova contributions. The optical afterglow of the GRB is initially a
power-law continuum but shows significant color variations during the first
week that are unrelated to the presence of a supernova. The early afterglow
light curve also shows deviations from the typical power-law decay. A supernova
spectrum is first detectable ~7 days after the burst and dominates the light
after ~11 days. The spectral evolution and the light curve are shown to closely
resemble those of SN 1998bw, a peculiar Type Ic SN associated with GRB 980425,
and the time of the supernova explosion is close to the observed time of the
GRB. It is now clear that at least some GRBs arise from core-collapse SNe.


title:
The X-ray eclipse of OY Car resolved with XMM-Newton: X-ray emission
  from the polar regions of the white dwarf

abstract:
  We present the XMM-Newton X-ray eclipse lightcurve of the dwarf nova OY Car.
The eclipse ingress and egress are well resolved for the first time in any
dwarf nova placing strong constraints on the size and location of the X-ray
emitting region. We find good fits to a simple linear eclipse model, giving
ingress/egress durations of 30+/-3 sec. Remarkably this is shorter than the
ingress/egress duration of the sharp eclipse in the optical as measured by Wood
et al. (1989) and ascribed to the white dwarf (43+/-2 sec). We also find that
the X-ray eclipse is narrower than the optical eclipse by 14+/-2 sec, which is
precisely the difference required to align the second and third contact points
of the X-ray and optical eclipses. We discuss these results and conclude that
X-ray emission in OY Car most likely arises from the polar regions of the white
dwarf.
  Our data were originally reported by Ramsay et al (2001), but they did not
make a quantitative measurement of eclipse parameters. We have also corrected
important timing anomalies present in the data available at that time.


title:
The End of the MACHO Era: Limits on Halo Dark Matter from Stellar Halo
  Wide Binaries

abstract:
  We simulate the evolution of halo wide binaries in the presence of MAssive
Compact Halo Objects (MACHOs) and compare our results to the sample of wide
binaries of Chaname & Gould (2003). The observed distribution is well fit by a
single power law for angular separation, 3.5" < theta < 900", whereas the
simulated distributions show a break in the power law whose location depends on
the MACHO mass and density. This allows us to place upper limits on MACHO
density as a function of their assumed mass. At the 95% confidence level, we
exclude MACHOs with mass M > 43Msun at the standard local halo density rho_H.
This all but removes the last permitted window for a full MACHO halo for masses
M > 10^{-7.5}Msun.


title:
Do Black Hole Candidates Have Magnetic Moments Instead of Event
  Horizons?

abstract:
  In previous work we found that many of the spectral properties of low mass
x-ray binaries (LMXB), including galactic black hole candiates (GBHC) were
consistent with the existence of intrinsically magnetized central objects. We
review and extend these findings and show that the existence of intrisically
magnetic BHC is consistent with a new class of solutions of the Einstein field
equations of General Relativity. These solutions are based on a strict
adherence to the Strong Principle of Equivalence (SPOE) requirement that the
world lines of physical matter must remain timelike in all regions of
spacetime. The new solutions emerge when the structure and radiation transfer
properties of the energy momentum tensor on the right hand side of the Einstein
field equations are appropriately chosen to dynamically enforce the SPOE
requirement of timelike world line completeness. In this context, we find that
the Einstein field equations allow the existence of highly red shifted,
Magnetospheric, Eternally Collapsing Objects (MECO). MECO can possess intrinsic
magnetic moments since they do not have trapped surfaces that lead to event
horizons and curvature singularities. Since MECO lifetimes are orders of
magnitude greater than a Hubble time, they provide an elegant and unified
framework for understanding a broad range of observations of GBHC and active
galactic nuclei. We examine their properties and discuss characteristics that
might lead to their confirmation.


title:
Effects of the Cosmological Constant as the Origin of the Cosmic-Ray
  Paradox

abstract:
  We show that a tiny but non-zero positive cosmological constant, which has
been strongly suggested by the recent astronomical observations on supernovae
and CMBR, may change notably the behaviors of the ultrahigh energy cosmic ray
interacting with soft photons. The threshold anomaly of the ultrahigh energy
cosmic ray disappears naturally after the effects of the cosmological constant
are taken into account.


title: Cross correlations of the cosmic infrared background

abstract:
  The cosmic infrared background (CIB) is a sensitive measure of the star
formation history. But this background is overwhelmed by foregrounds, which
bias the CIB mean flux and auto correlation measurement severely. Since
dominant foregrounds do not correlate with the large scale structure, the cross
correlation of CIB with galaxies is free of such foregrounds and presents as an
unbiased measure of the star formation history. This also allows the
measurement of CIB based on integrated intensity, whose theoretical prediction
is based on energy conservation, thus is fairly model independent and robust.
The redshift information of CIB sources can be directly recovered with the aid
of galaxy photometric redshifts. In the far IR region, correlation signal is
around 10% at degree scale. Combining FIRAS and SDSS, the cross correlation can
be measured with 20% accuracy (statistical and systematics errors) at $l\sim
40$. Such measurement would allow the measurement of star formation rate with
comparable accuracies to $z\sim 1$. Future CIB experiments with $1^{\circ}$
resolution are able to measure the star formation rate with 10% accuracy to
$z\sim 1.5$. Secondary CMB anisotropies arising from the large scale structure
correlate with CIB. The correlation strength is about $0.5\mu$K at $\sim
10^{\circ}$ (the integrated Sachs-Wolfe effect) and $\sim -0.3\mu$K at $\sim
1^{\circ}$ (the Sunyaev Zeldovich effect, Rayleigh-Jeans regime). FIRAS+WMAP
would allow the measurement of the ISW effect with $\ga 5\sigma$ confidence.
Its detection helps to constrain the amount of dark energy and far IR
emissivity bias.


title:
Dark Energy and the Statistical Study of the Observed Image Separations
  of the Multiply Imaged Systems in the CLASS Statistical Sample

abstract:
  The present day observations favour a universe which is flat, accelerated and
composed of $\sim 1/3$ matter (baryonic + dark) and $\sim 2/3$ of a negative
pressure component, usually referred to as dark energy or quintessence. The
Cosmic Lens All Sky Survey (CLASS), the largest radio-selected galactic mass
scale gravitational lens search project to date, has resulted in the largest
sample suitable for statistical analyses. In the work presented here, we
exploit observed image separations of the multiply imaged lensed radio sources
in the sample. We use two different tests: (1) image separation distribution
function $n(\Delta\theta)$ of the lensed radio sources and (2)
${\dtheta}_{\mathrm{pred}}$ vs ${\dtheta}_{\mathrm{obs}}$ as observational
tools to constrain the cosmological parameters $w$ and $\Om$. The results are
in concordance with the bounds imposed by other cosmological tests.


title:
Realistic cosmological model with dynamical cancellation of vacuum
  energy

abstract:
  We propose a model with a compensating scalar field whose back reaction to
the cosmological curvature cancels possible vacuum energy density down to the
terms of the order of the time dependent critical energy density. Thus the
model simultaneously solves the mystery of the compensation of vacuum energy
with the accuracy of 120 orders of magnitude and explains existence of the
observed dark energy. At an early stage the suggested cosmological model might
experience exponential expansion without an additional inflaton field.


title: Submillimetre observations of a sample of broad absorption line quasars

abstract:
  The broad absorption line (BAL) features seen in a small fraction of quasar
optical/UV spectra are attributed to bulk outflows away from the quasar core.
Observational evidence suggests that dust plays a key role in these systems,
although whether the inferred dust properties are a signature of orientation
effects or whether they are indicative of an evolutionary sequence remains an
outstanding issue. Submillimetre (submm) detections of BAL quasars (BALQSOs),
which would clearly help to resolve this issue, have so far been sparse. This
paper reports on new submm observations of seven BALQSOs. The strongest
influence on the observed flux is found to be the redshift, with the two
highest redshift sources appearing intrinsically more submm-luminous than the
lower redshift ones. Since this trend is also seen in other high redshift AGN,
including non-BAL quasars it implies that the dust emission properties of these
systems are no different from those of the general AGN population, which is
difficult to reconcile with the evolutionary interpretation of the BAL
phenomenon.


title:
Will LIGO see RIGO's? - Radion-induced graviton oscillations in the
  two-brane world

abstract:
  One of the most interesting features of braneworld models is the existence of
massive gravitational modes in addition to the usual massless one. Mixing of
the modes which depends nontrivially on the inter-brane distance can be
interpreted as radion-induced gravitational-wave oscillations, a classical
analogy to meson and neutrino oscillations. We show that these oscillations
arising in M-theory inspired two-brane setups could lead to effects detectable
by gravitational-wave interferometers.


title:
The Chemical Evolution of Magnesium Isotopic Abundances in the Solar
  Neighbourhood

abstract:
  The abundance of the neutron-rich magnesium isotopes observed in metal-poor
stars is explained quantitatively with a chemical evolution model of the local
Galaxy that considers - for the first time - the metallicity-dependent
contribution from intermediate mass stars. Previous models that simulate the
variation of Mg isotopic ratios with metallicity in the solar neighbourhood
have attributed the production of Mg25 and Mg26 exclusively to hydrostatic
burning in massive stars.
  These models match the data well for [Fe/H]>-1.0 but severely underestimate
Mg25/Mg24 and Mg26/Mg24 at lower metallicities. Earlier studies have noted that
this discrepancy may indicate a significant role played by intermediate-mass
stars. Only recently have detailed calculations of intermediate-mass stellar
yields of Mg25 and Mg26 become available with which to test this hypothesis. In
an extension of previous work, we present a model that successfully matches the
Mg isotopic abundances in nearby Galactic disk stars through the incorporation
of nucleosynthesis predictions of Mg isotopic production in asymptotic giant
branch stars.


title:
The extended tails of Palomar 5: A ten degree arc of globular cluster
  tidal debris

abstract:
  Using wide-field photometric data from the Sloan Digital Sky Survey (SDSS) we
recently showed that the Galactic globular cluster Palomar 5 is in the process
of being tidally disrupted. Its tidal tails were initially detected in a 2.5
degree wide band along the celestial equator. A new analysis of SDSS data for a
larger field now reveals that the tails of Pal 5 have a much larger spatial
extent and can be traced over an arc of 10 deg across the sky, corresponding to
a projected length of 4 kpc at the distance of the cluster. The number of
former cluster stars found in the tails adds up to about 1.2 times the number
of stars in the cluster. The radial profile of stellar surface density in the
tails follows approximately a power law r^gamma with -1.5 < gamma < -1.2.
  The stream of debris from Pal 5 is significantly curved, which demonstrates
its acceleration by the Galactic potential. The cluster is presently near the
apocenter but has repeatedly undergone disk crossings in the inner part of the
Galaxy leading to strong tidal shocks. Our results suggest that the observed
debris originates mostly from mass loss within the last 2 Gyrs. The cluster is
likely to be destroyed after the next disk crossing, which will happen in about
100 Myr. (abridged)


title: A Dynamical Systems Approach to an Inviscid and Thin Accretion Disc

abstract:
  The inviscid and thin accretion disc is a simple and well understood model
system in accretion studies. In this work, modelling such a disc like a
dynamical system, we analyse the nature of the fixed points of the stationary
solutions of the flow. We show that of the two fixed points, one is a saddle
and the other is a centre type point. We then demonstrate, using a simple but
analogous mathematical model, that a temporal evolution of the flow is a very
likely non-perturbative mechanism for the selection of an inflow solution that
passes through the saddle type critical point.


title: Temporal fluctuations in the differential rotation of cool active stars

abstract:
  This paper reports positive detections of surface differential rotation on
two rapidly rotating cool stars at several epochs, by using stellar surface
features (both cool spots and magnetic regions) as tracers of the large scale
latitudinal shear that distorts the convective envelope in this type of stars.
We also report definite evidence that this differential rotation is different
when estimated from cool spots or magnetic regions, and that it undergoes
temporal fluctuations of potentially large amplitude on a time scale of a few
years. We consider these results as further evidence that the dynamo processes
operating in these stars are distributed throughout the convective zone rather
than being confined at its base as in the Sun. By comparing our observations
with two very simple models of the differential rotation within the convective
zone, we obtain evidence that the internal rotation velocity field of the stars
we investigated is not like that of the Sun, and may resemble that we expect
for rapid rotators. We speculate that the changes in differential rotation
result from the dynamo processes (and from the underlying magnetic cycle) that
periodically converts magnetic energy into kinetic energy and vice versa. We
emphasise that the technique outlined in this paper corresponds to the first
practical method for investigating the large scale rotation velocity field
within convective zones of cool active stars, and offers several advantages
over asteroseismology for this particular purpose and this specific stellar
class.


title:
Astrometry with Hubble Space Telescope: A Parallax of the Central Star
  of the Planetary Nebula NGC 6853

abstract:
  We present an absolute parallax and relative proper motion for the central
star of the planetary nebula NGC 6853 (The Dumbell). We obtain these with
astrometric data from FGS 3, a white-light interferometer on {\it HST}.
Spectral classifications and VRIJHKT$_2$M and DDO51 photometry of the stars
comprising the astrometric reference frame provide spectrophotometric estimates
of their absolute parallaxes. Introducing these into our model as observations
with error, we find $\pi_{abs} = 2.10 \pm 0.48$ mas for the DAO central star of
NGC 6853. A weighted average with a previous ground-based USNO determination
yields $\pi_{abs} = 2.40 \pm 0.32$. We assume that the extinction suffered by
the reference stars nearest (in angular separation and distance) to the central
star is the same as for the central star. Correcting for color differences, we
find $<$A$_V>$ = 0.30 $ \pm $ 0.06 for the central star, hence, an absolute
magnitude M$_V = 5.48^{-0.16}_{+0.15}$. A recent determination of the central
star effective temperature aided in estimating the central star radius,
$R_{*}=0.055 \pm 0.02R_{\sun}$, a star that may be descending to the white
dwarf cooling track.


title: The spectrum of a single photoionized cloud

abstract:
  The emission-line spectrum of a quasar is most likely emitted by an ensemble
of photoionized clouds moving with a variety of velocities, with a range of
densities and distances from the central object. The state of the art in this
field is to first compute the emission from a single cloud, and then prescribe
a mix of clouds to reproduce line intensities, profiles, and reverberation
lags. Here I review the parameters that de-fine emission from a single cloud
and the outstanding problems in qua-sar emission-line analysis.


title: Cosmic Reionisation by Stellar Sources: Population III Stars

abstract:
  We combine fast radiative transfer calculations with high resolution
hydrodynamical simulations to study an epoch of early hydrogen reionisation by
primordial stellar sources at redshifts 15<z<30. With relatively conservative
assumptions, population III star formation proceeds in a self-regulated manner
both locally and globally and, for a conventional LCDM cosmology, can
significantly reionise the intergalactic medium between 15<z<20 as long as a
large fraction of ionising photons can escape from these earliest galaxies. We
then combine these results with our earlier work focusing on the role of
population II stars in galaxies with virial temperatures >10^4K at redshifts
5<z< 20. Hence, we construct a complete reionisation history of the Universe
which matches the Thomson optical depths as measured by the WMAP satellite as
well as the evolution of the Gunn Peterson optical depth as seen in the
asborption spectra of the higest redshift quasars. We find that even with
conservative estimates for the impact of negative feedback mechanisms,
primordial stellar sources contribute significantly to early reionisation.
Future observations of a Thomson optical depth of tau_e>~0.13 would bolster the
claim for the existence of population III stars similar to the ones studied
here.


title: H.E.S.S. contributions to the 28th International Cosmic Ray Conference

abstract:
  This preprint encompasses 14 individual contributions of the H.E.S.S.
collaboration to the 28th ICRC: Status, Performance of the cameras, Observation
of Galactic and extra Galactic sources, Performance of the telescope,
Application of a shower fitting algorithm, DAQ, Mirror alignment, Calibration,
Pointing, Flat-fielding with LEDs, Atmospheric monitoring, LIDAR monitoring,
Optical pulse measurement from the Crab nebula


title:
Model Dependence of Lateral Distribution Functions of High Energy Cosmic
  Ray Air Showers

abstract:
  The influence of high and low energy hadronic models on lateral distribution
functions of cosmic ray air showers for AUGER energies is explored. A large
variety of presently used high and low energy hadron interaction models are
analysed and the resulting lateral distribution functions are compared. We show
that the slope as well as the signal at 1000 m distance from the shower axis
depend on both the high and low energy hadronic model used. The models are
confronted with available hadron-nucleus data from accelerator experiments.


title:
Collimated Outflow Formation via Binary Stars. 3-D Simulations of AGB
  Wind and Disk Wind Interactions

abstract:
  We present three-dimensional hydrodynamic simulations of the interaction of a
slow wind from an asymptotic giant branch(AGB) star and a jet blown by an
orbiting companion. The jet or "Collimated Fast Wind" is assumed to originate
from an accretion disk which forms via Bondi accretion of the AGB wind or Roche
lobe overflow. We present two distinct regimes in the wind-jet interaction
determined by the ratio of the AGB wind to jet momentum flux. Our results show
that when the wind momentum flux overwhelms the flux in the jet a more
dis-ordered outflow outflow results with the jet assuming a corkscrew pattern
and multiple shock structures driven into the AGB wind. In the opposite regime
the jet dominates and will drive a highly collimated narrow waisted outflow. We
compare our results with scenarios described by Soker & Rappaport (2000) and
extrapolate the structures observed in PNe and Symbiotic stars.


title:
Protostellar Disk Dynamos and Hydromagnetic Outflows in Primordial Star
  Formation

abstract:
  Are magnetic fields important in primordial star formation? Assuming that
star formation occurs via an accretion disk that is turbulent, initially
because of local gravitational instability, we calculate the disk structure for
realistic accretion rates. We predict that local gravitational viscosity is
able to drive accretion, without the disk fragmenting. We then estimate the
rate of dynamo amplification of seed magnetic field. Turbulence in a stratified
disk can be helical, with different signs of the helicity in each hemisphere.
This provides a key ingredient for production of global scale magnetic fields
whose sign of flux is sustained over many orbit times. The resulting fields can
drive collimated protostellar outflows that reduce the star formation
efficiency from the initial gas cloud, especially once the protostar has
contracted to the main sequence, at ~100 Msun. We estimate that the outflows
are powerful enough to eject some material from the host dark matter halo and
to initiate relatively strong magnetization of the local intergalactic medium.
Close to the protostar, the outflow acts to shield the disk and equatorial
regions from radiative feedback, such as ionizing photons, and this may enable
accretion up to relatively large stellar masses. We conclude that magnetic
fields cannot be ignored from models of primordial star formation.


title:
Charge separation effects in magnetized electron-ion plasma expansion
  into a vacuum

abstract:
  Charge separation effects in the expansion of magnetized relativistic
electron-ion plasmas into a vacuum are examined using 2-1/2-dimensional
particle-in-cell plasma simulations. The electrostatic field at the plasma
surface decelerates electrons and accelerates ions. A fraction of the surface
electrons are trapped and accelerated by the pondermotive force of the
propagating electromagnetic pulse, a mechanism we call the DRPA (diamagnetic
relativistic pulse accelerator). This charge separation is enhanced as the
initial plasma temperature is decreased. The overall energy gain of the plasma
particles through the expansion strongly depends on the initial plasma
temperature. Moreover, the electrons become relatively less energized and the
ions more energized as the plasma temperature decreases.


title:
The Birmingham-CfA cluster scaling project - II. Mass composition and
  distribution

abstract:
  We investigate the spatial distribution of the baryonic and non-baryonic mass
components in a sample of 66 virialized systems. We have used X-ray
measurements to determine the deprojected temperature and density structure of
the intergalactic medium and have employed these to map the underlying
gravitational potential. In addition, we have measured the deprojected spatial
distribution of galaxy luminosity for a subset of this sample, spanning over 2
decades in mass. With this combined X-ray/optical study we examine the scaling
properties of the baryons and address the issue of mass-to-light (M/L) ratio in
groups and clusters of galaxies. We measure a median mass-to-light ratio of 224
h70 M/L (solar) in the rest frame B_j band, in good agreement with other
measurements based on X-ray determined masses. There is no trend in M/L with
X-ray temperature and no significant trend for mass to increase faster than
luminosity: M \propto \L_{B,j}^{1.08 +/- 0.12}. This implied lack of
significant variation in star formation efficiency suggests that gas cooling
cannot be greatly enhanced in groups, unless it drops out to form baryonic dark
matter. Correspondingly, our results indicate that non-gravitational heating
must have played a significant role in establishing the observed departure from
self-similarity in low mass systems. The median baryon fraction for our sample
is 0.162 h70^{-3/2}, which allows us to place an upper limit on the
cosmological matter density, Omega_m <= 0.27 h70^{-1}, in good agreement with
the latest results from WMAP. We find evidence of a systematic trend towards
higher central density concentration in the coolest haloes, indicative of an
early formation epoch and consistent with hierarchical formation models.


title:
Detection of Low-Hard State Spectral and Timing Signatures from the
  Black Hole X-Ray Transient XTE J1650-500 at Low X-Ray Luminosities

abstract:
  Using the Chandra X-ray Observatory and the Rossi X-ray Timing Explorer, we
have studied the black hole candidate (BHC) X-ray transient XTE J1650-500 near
the end of its 2001-2002 outburst after its transition to the low-hard state at
X-ray luminosities down to L = 1.5E34 erg/s (1-9 keV, assuming a source
distance of 4 kpc). Our results include a characterization of the spectral and
timing properties. At the lowest sampled luminosity, we used an 18 ks Chandra
observation to measure the power spectrum at low frequencies. For the 3 epochs
at which we obtained Chandra/RXTE observations, the 0.5-20 keV energy spectrum
is consistent with a spectral model consisting of a power-law with interstellar
absorption. We detect evolution in the power-law photon index from 1.66 +/-
0.05 to 1.93 +/- 0.13 (90% confidence errors), indicating that the source
softens at low luminosities. The power spectra are characterized by strong
(20-35% fractional rms) band-limited noise, which we model as a zero-centered
Lorentzian. Including results from an RXTE study of XTE J1650-500 near the
transition to the low-hard state by Kalemci et al. (2003), the half-width of
the zero-centered Lorentzian (roughly where the band-limited noise cuts off)
drops from 4 Hz at L = 7E36 erg/s (1-9 keV, absorbed) to 0.067 +/- 0.007 Hz at
L = 9E34 erg/s to 0.0035 +/- 0.0010 Hz at the lowest luminosity. While the
spectral and timing parameters evolve with luminosity, it is notable that the
general shapes of the energy and power spectra remain the same, indicating that
the source stays in the low-hard state. This implies that the X-ray emitting
region of the system likely keeps the same overall structure, while the
luminosity changes by a factor of 470. We discuss how these results may
constrain theoretical black hole accretion models.


title: An upper bound on the number of e-foldings

abstract:
  If the present acceleration of the universe is due to an asymptotically de
Sitter universe with small cosmological constant, and the principle of
Cosmological Complementarity is valid, then the number of e-foldings during
inflation is bounded.


title:
Probing Dark Energy with Baryonic Acoustic Oscillations from Future
  Large Galaxy Redshift Surveys

abstract:
  We show that the measurement of the baryonic acoustic oscillations in large
high redshift galaxy surveys offers a precision route to the measurement of
dark energy. The cosmic microwave background provides the scale of the
oscillations as a standard ruler that can be measured in the clustering of
galaxies, thereby yielding the Hubble parameter and angular diameter distance
as a function of redshift. This, in turn, enables one to probe dark energy. We
use a Fisher matrix formalism to study the statistical errors for redshift
surveys up to z=3 and report errors on cosmography while marginalizing over a
large number of cosmological parameters including a time-dependent equation of
state. With redshifts surveys combined with cosmic microwave background
satellite data, we achieve errors of 0.037 on Omega_x, 0.10 on w(z=0.8), and
0.28 on dw(z)/dz for cosmological constant model. Models with less negative
w(z) permit tighter constraints. We test and discuss the dependence of
performance on redshift, survey conditions, and fiducial model. We find results
that are competitive with the performance of future supernovae Ia surveys. We
conclude that redshift surveys offer a promising independent route to the
measurement of dark energy.


title: The complex FeK line of the Narrow-Line Seyfert 1 galaxy IRAS13349+2438

abstract:
  The observation of the Narrow-Line Seyfert 1 galaxy IRAS13349+2438 performed
by XMM-Newton European Photon Imaging Camera between 0.3-10 keV, is presented
here. The broadband spectrum of the source is dominated at low energies (E < 2
keV) by a strong excess of emission and by complex emission/absorption features
between 5.5-8.0 keV. The soft X-ray spectrum is consistent with ionized
absorption found by the Reflection Grating Spectrometer (Sako et al. (2001)).
We focus on the 2-10 keV spectrum which shows clear evidence for a broad,
complex FeK alpha line, previously unseen by ASCA, and for an Fe K-shell edge
detected at ~7.3-7.4 keV (rest-frame). The presence of this edge could be
explained by either partial covering or ionized/relativistic reflection models,
with the latter being preferred and with a resulting power law slope of Gamma
\~2.2. The line profile is complex, with a broad bump between ~ 5.5-6.5 keV and
a narrow emission line at ~ 7 keV, separated by a sharp drop at ~ 6.8 keV. This
profile is compatible with two possible scenarios: i) a broad, ionized and
gravitationally redshifted Laor diskline plus a narrow and ionized emission
line; ii) a broad, ionized and single Schwarzschild (double-peaked) diskline
with a superimposed narrow absorption line.


title: Circular Polarization from Gamma-ray Burst Afterglows

abstract:
  We investigate the circular polarization (CP) from Gamma-Ray Burst (GRB)
afterglows. We show that a tangled magnetic field cannot generate CP without an
ordered magnetic field because there is always an oppositely directed field, so
that no handedness exists. This implies the observation of CP could be a useful
probe of an ordered field, which carries valuable information on the GRB
central engine. By solving the transfer equation of polarized radiation, we
find that the CP reaches 1% at radio frequencies and 0.01% at optical for the
forward shock, and 10-1% at radio and 0.1-0.01% at optical for the reverse
shock.


title: Improved Estimates of Cosmological Perturbations

abstract:
  We recently derived exact solutions for the scalar, vector and tensor mode
functions of a single, minimally coupled scalar plus gravity in an arbitrary
homogeneous and isotropic background. These solutions are applied to obtain
improved estimates for the primordial scalar and tensor power spectra of
anisotropies in the cosmic microwave background.


title:
The spectrum of the roAp star HD 101065(Przybylski's star) in the Li I
  6708 A spectral region

abstract:
  We carried out a detailed analysis of spectra of the unique roAp star HD
101065 (Przybylski's star) near the resonance doublet Li I 6708 A, using a most
complete line list including all possible transitions between REE levels of
NIST database. Our model calculations were performed under two assumptions:
blend of Li and REE lines, and blend of REE lines only. They prove that Li
lines are present in the range 6707.72-6708.02 AA, and that the resulting Li
abundance is 3.1 dex (in the scale log N(H) = 12.0, while the isotopic ratio
6Li/7Li is near to 0.3.


title:
Constraining Compact Dark Matter with Quasar Equivalent Widths from the
  Sloan Digital Sky Survey Early Data Release

abstract:
  Cosmologically distributed compact dark matter objects with masses in the
approximate range of 0.001 to 1 solar masses can amplify the continuum emission
of a quasar through gravitational microlensing, without appreciably affecting
its broad emission lines. This will produce a statistical excess of weak-lined
quasars in the observed distribution of spectral line equivalent widths, an
effect that scales with the amount of compact dark matter in the universe.
Using the large flux-limited sample of quasar spectra from the Early Data
Release of the Sloan Digital Sky Survey (SDSS), I demonstrate the absence of a
strong microlensing signal. This leads to a constraint on the cosmological
density of compact objects of Omega_c < 0.03, relative to the critical density,
on Jupiter- to solar-mass scales. For compact objects clustered in galaxy
halos, this limit is expected to be weaker by at most a factor of two. I also
forecast the improvements to this constraint that may be possible in a few
years with the full SDSS quasar catalog.


title:
Magnetohydrodynamic Density Waves in a Composite Disk System of
  Interstellar Medium and Cosmic-Ray Gas

abstract:
  Multi-wavelength observations from radio to soft X-ray bands of large-scale
galactic spiral structures offer synthesized and comprehensive views of nearby
disk galaxies. In the presence of a massive dark-matter halo, the density-wave
dynamics on galactic scales involves the stellar disk, the gas disk of
interstellar medium (ISM), the magnetic field, and the cosmic-ray gas (CRG). In
this paper, we explore the dynamic and electromagnetic interplay between the
magnetized ISM disk and CRG disk so that structural and diagnostic features of
optical, infrared, and synchrotron radio-continuum emissions from a spiral
galaxy can be physically understood. On timescales of galactic density waves,
cosmic rays collectively may be treated as a relativistically hot tenuous gas
fluid that is tied to the large-scale mean magnetic field in transverse bulk
motions but moves otherwise differently along the magnetic field relative to
the ISM. For both fast and slow magnetohydrodynamic (MHD) density waves in a
composite disk system of magnetized ISM and CRG, the minute CRG mass density
enhancement is phase shifted relative to the enhancement of parallel magnetic
field. Owing to an extremely small number of cosmic rays, the large-scale
magnetic field enhancement dominates in synchrotron radio-continuum emissions
(as if the CRG is almost unperturbed) for spiral structural manifestations. In
addition to the fast and slow MHD density waves, there also exists a
suprathermal MHD wave mode by which CRG adjusts itself with an effective
suprathermal sound speed close to the speed of light c.


title:
A Long Look at NGC 3783 with the XMM-Newton Reflection Grating
  Spectrometers

abstract:
  A long 280 ks observation of the Seyfert 1 galaxy NGC 3783 with XMM-Newton is
reported. We focus on the oxygen line complex between 17 and 24 A as measured
with the RGS spectrometers. Accurate absorption column densities and emission
line fluxes are obtained. We explore several options for the geometry and
physical form of the emitting and absorbing gas. The lack of change in
ionization in the absorber despite an increase in continuum flux during the
observation restricts the high-ionization (O-K) and the low-ionization (Fe-M)
gas to distances of at least 0.5 pc and 2.8 pc, respectively, away from the
central source. Given the P-Cygni type profiles in the resonance spectral lines
and the similar velocity widths, column densities, and ionization structure
inferred separately from the emission and absorption lines, it is tempting to
relate the X-ray narrow-line emitting plasma with the X-ray absorbing gas.
Under this assumption, the scenario of dense clumped clouds can be ruled out.
Conversely, extended ionization cones (r > 10 pc) are consistent with the
observation independent of this assumption. These findings are in stark
contrast with the picture of numerous clumpy (n_e > 10^9 cm^-3) clouds drawn
recently from UV spectra, but it is consistent with the extended X-ray emission
cones observed directly in Seyfert 2 galaxies.


title:
Self-consistency of relativistic observables with general relativity in
  the white dwarf-neutron star binary pulsar PSR J1141-6545

abstract:
  Here we report timing measurements of the relativistic binary pulsar PSR
J1141-6545 that constrain the component masses and demonstrate that the orbital
period derivative \dot Pb = (-4+/-1)x10^-13 is consistent with gravitational
wave emission as described by the general theory of relativity. The mass of the
neutron star and its companion are 1.30+/-0.02 Mo and 0.986+/-0.020 Mo
respectively, suggesting a white dwarf companion, and extending the range of
systems for which general relativity provides a correct description. On
evolutionary grounds, the progenitor mass of PSR J1141-6545 should be near the
minimum for neutron star production. Its mass is two standard deviations below
the mean of the other neutron stars, suggesting a relationship between
progenitor and remnant masses.


title:
Non-Gaussian Signatures in the Temperature Fluctuation Observed by the
  Wilkinson Microwave Anisotropy Probe

abstract:
  We present results from a test for the Gaussianity of the whole sky
sub-degree scale CMB temperature anisotropy measured by the Wilkinson Microwave
Anisotropy Probe (WMAP). We calculate the genus from the foreground-subtracted
and Kp0-masked WMAP maps and measure the genus shift parameters defined at
negative and positive threshold levels and the asymmetry parameter to quantify
the deviation from the Gaussian relation. At WMAP Q, V, and W bands, the genus
and genus-related statistics imply that the observed CMB sky is consistent with
Gaussian random phase field. However, from the genus measurement on the
Galactic northern and southern hemispheres, we have found two non-Gaussian
signatures at the W band resolution (0.35 degree scale), i.e., the large
difference of genus amplitudes between the north and the south and the positive
genus asymmetry in the south, which are statistically significant at 2.6 sigma
and 2.4 sigma levels, respectively. The large genus amplitude difference also
appears in the WMAP Q and V band maps, deviating the Gaussian prediction with a
significance level of about 2 sigma. The probability that the genus curves show
such a large genus amplitude difference exceeding the observed values at all Q,
V, and W bands in a Gaussian sky is only 1.4%. Such non-Gaussian features are
reduced as the higher Galactic cut is applied, but their dependence on the
Galactic cut is weak. We discuss possible sources that can induce such
non-Gaussian features, and conclude that the CMB data with higher
signal-to-noise ratio and the accurate foreground model are needed to
understand the non-Gaussian signatures.


title:
The Star Formation History of Galaxies Measured from Individual Pixels.
  I. The Hubble Deep Field North

abstract:
  We analyze the photometric information contained in individual pixels of
galaxies in the Hubble Deep Field North (HDFN) using a new technique,
_pixel-z_, that combines predictions of evolutionary synthesis models with
photometric redshift template fitting. Each spectral energy distribution
template is a result of modeling of the detailed physical processes affecting
gas properties and star formation efficiency. The criteria chosen to generate
the SED templates is that of sampling a wide range of physical characteristics
such as age, star formation rate, obscuration and metallicity. A key feature of
our method is the sophisticated use of error analysis to generate error maps
that define the reliability of the template fitting on pixel scales and allow
for the separation of the interplay among dust, metallicity and star formation
histories. This technique offers a number of advantages over traditional
integrated color studies. As a first application, we derive the star formation
and metallicity histories of galaxies in the HDFN. Our results show that the
comoving density of star formation rate, determined from the UV luminosity
density of sources in the HDFN, increases monotonically with redshift out to at
least redshift of 5. This behavior can plausibly be explained by a smooth
increase of the UV luminosity density with redshift coupled with an increase in
the number of star forming regions as a function of redshift. We also find that
the information contained in individual pixels in a galaxy can be linked to its
morphological history. Finally, we derive the metal enrichment rate history of
the universe and find it in good agreement with predictions based on the
evolving HI content of Lyman-alpha QSO absorption line systems.


title: Heating cooling flows with jets

abstract:
  Active galactic nuclei are clearly heating gas in `cooling flows'. The
effectiveness and spatial distribution of the heating are controversial. We use
three-dimensional simulations on adaptive grids to study the impact on a
cooling flow of weak, subrelativistic jets. The simulations show cavities and
vortex rings as in the observations. The cavities are fast-expanding dynamical
objects rather than buoyant bubbles as previously modelled, but shocks still
remain extremely hard to detect with X-rays. At late times the cavities turn
into overdensities that strongly excite the cluster's g-modes. These modes damp
on a long timescale. Radial mixing is shown to be an important phenomenon, but
the jets weaken the metallicity gradient only very near the centre. The central
entropy density is modestly increased by the jets. We use a novel algorithm to
impose the jets on the simulations.


title: Gravitational Waves from Axisymmetric, Rotational Stellar Core Collapse

abstract:
  We have carried out an extensive set of two-dimensional, axisymmetric,
purely-hydrodynamic calculations of rotational stellar core collapse with a
realistic, finite-temperature nuclear equation of state and realistic massive
star progenitor models. For each of the total number of 72 different
simulations we performed, the gravitational wave signature was extracted via
the quadrupole formula in the slow-motion, weak-field approximation. We
investigate the consequences of variation in the initial ratio of rotational
kinetic energy to gravitational potential energy and in the initial degree of
differential rotation. Furthermore, we include in our model suite progenitors
from recent evolutionary calculations that take into account the effects of
rotation and magnetic torques. For each model, we calculate gravitational
radiation wave forms, characteristic wave strain spectra, energy spectra, final
rotational profiles, and total radiated energy. In addition, we compare our
model signals with the anticipated sensitivities of the 1st- and 2nd-generation
LIGO detectors coming on line. We find that most of our models are detectable
by LIGO from anywhere in the Milky Way.


title: The new AM CVn star in Hydra

abstract:
  High speed photometry of the new AM CVn star in Hya (previously known as
SN2003aw), spectroscopically identified by Chornock & Filippenko, shows it to
have a superhump period of 2041.5 +/- 0.3 s. We find a range of brightness from
V ~ 16.5 to 20.3, presumably caused by variations in the rate of mass transfer.
In the intermediate state the system cycles in brightness with a period of ~ 16
h and range >= 0.4 mag. There are sidebands to the principal frequencies in the
Fourier transform which have constant frequency difference from the superhump
harmonics.


title: INTEGRAL observations of the black hole candidate H 1743-322 in outburst

abstract:
  INTEGRAL made 3 observations in 2003 April of the black hole candidate H
1743-322 during the rising part, and close to the maximum, of an outburst. H
1743-322 was previously observed in outburst in 1977-1978. The source is
located in a crowded region of the sky (l = 357 deg, b = -2 deg) and at least
18 sources are clearly detected in the field of view of the gamma-ray imager
during a 277 ksec exposure. These are well known persistent X-ray binaries and
3 transient sources in outburst. The combined 5-200 keV JEM-X and SPI spectrum
of H 1743-322 is well fit with an absorbed ((2.5 10E22 atom/cm2) soft (photon
index 2.70 +/- 0.09) power-law model consistent with J 1743-322 being in a
high/soft state.


title:
An infrared imaging search for low-mass companions to members of the
  young nearby beta Pic and Tucana/Horologium associations

abstract:
  We present deep high dynamic range infrared images of young nearby stars in
the Tucana/Horologium and beta Pic associations, all ~ 10 to 35 Myrs young and
at ~10 to 60 pc distance. Such young nearby stars are well-suited for direct
imaging searches for brown dwarf and even planetary companions, because young
sub-stellar objects are still self-luminous due to contraction and accretion.
We performed our observations at the ESO 3.5m NTT with the normal infrared
imaging detector SofI and the MPE speckle camera Sharp-I. Three arc sec north
of GSC 8047-0232 in Horologium a promising brown dwarf companion candidate is
detected, which needs to be confirmed by proper motion and/or spectroscopy.
Several other faint companion candidates are already rejected by second epoch
imaging. Among 21 stars observed in Tucana/Horologium, there are not more than
one to five brown dwarf companions outside of 75 AU (1.5" at 50 pc); most
certainly only < 5 % of the Tuc/HorA stars have brown dwarf companions (13 to
78 Jupiter masses) outside of 75 AU. For the first time, we can report an upper
limit for the frequency of massive planets (~ 10 M_jup) at wide separations (~
100 AU) using a meaningfull and homogeneous sample: Of 11 stars observed
sufficiently deep in beta Pic (12 Myrs), not more than one has a massive planet
outside of ~ 100 AU, i.e. massive planets at large separations are rare (< 9
%).


title:
Improvements to Existing Transit Detection Algorithms and Their
  Comparison

abstract:
  In Tingley (2003), all available transit detection algorithms were compared
in a simple, rigorous test. However, the implementation of the Box-fitting
Least Squares (BLS) approach of Kovacs et al. (2002) used in that paper was not
ideal for those purposes. This letter revisits the comparison, using a version
of the BLS better suited to the task at hand and made more efficient via the
knowledge gained from the previous work. Multiple variations of the BLS and the
matched filter are tested. Some of the modifications improve performance to
such an extent that the conclusions of the original paper must be revised.


title: Early Cosmology and Fundamental Physics

abstract:
  This is a pedagogical introduction to early cosmology and the host of
fundamental physics involved in it (particle physics, grand unification and
general relativity). Inflation and the inflaton field are the central theme of
this review. The quantum field treatment of the inflaton is presented including
its out of equilibrium evolution and the use of nonperturbative methods. The
observational predictions for the CMB anisotropies are briefly discussed.
Finally, open problems and future perspectives in connection with dark energy
and string theory are overviewed.


title: Particle Splitting: A New Method for SPH Star Formation Simulations

abstract:
  We have invented a new algorithm to use with self-gravitating SPH Star
Formation codes. The new method is designed to enable SPH simulations to
self-regulate their numerical resolution, i.e. the number of SPH particles; the
latter is calculated using the Jeans condition (Bate & Burkert 1997) and the
local hydrodynamic conditions of the gas. We apply our SPH with Particle
Splitting code to cloud-cloud collision simulations. Chapter 2 lists the
properties of our standard SPH code. Chapter 3 discusses the efficiency of the
standard code as this is applied to simulations of rotating, uniform clouds
with m=2 density perturbations. Chapter 4 [astro-ph/0203057] describes the new
method and the tests that it has successfully been applied to. It also contains
the results of the application of Particle Splitting to the case of rotating
clouds as those of Chapter 3, where, with great computational efficiency, we
have reproduced the results of FD codes and SPH simulations with large numbers
of particles. Chapter 5 gives a detailed account of the cloud-cloud collisions
studied, starting from a variety of initial conditions produced by altering the
cloud mass, cloud velocity and the collision impact parameter. In the majority
of the cases studied, the collisions produced filaments (similar to those
observed in ammonia in nearby Star Forming Regions) or networks of filaments;
groups of protostellar cores have been produced by fragmentation of the
filaments. The accretion rates at these cores are comparable to those of Class
0 objects. Due to time-step constraints the simulations stop early in their
evolution. The star formation efficiency of this mechanism is extrapolated in
time and is found to be 10-20%.


title: Homogeneity of early-type galaxies across clusters

abstract:
  We studied the homogeneity, across clusters, of the color of the red sequence
(the intercept of the color--magnitude relation) of 158 clusters and groups
detected in the Early Data Release of the Sloan Digital Sky Survey (EDR-SDSS)
in the redshift range 0.06<z<0.34. We found a high degree of homogeneity: the
color of the red sequence shows an intrinsic scatter of 0.02 mag across
clusters, suggesting that either galaxies on the red sequence formed a long
time ago (z>2) or else their star formation is universally delayed with
preservation of a small spread in age formation. The latter possibility is
ruled out by the mere existence of galaxies at high redshift. While the old age
of ellipticals was already been claimed for a small heterogeneous collection of
clusters, most of which are rich ones, we found that it holds for ten to one
hundred large sample, representative of all clusters and groups detected on the
EDR-SDSS. Hence we suggest the possible universality of the color of the
galaxies on the red sequence. The observed red sequence color does not depend
on cluster/group richness at a level of 0.02 mag, while a ~0.23 mag effect is
expected according to the hierarchical prediction. Therefore, the stellar
population of red sequence galaxies is similar in clusters and groups, in spite
of different halo histories. Finally, since the observed rest--frame color of
the red sequence does not depend on environment and redshift, it can be used as
a distance indicator, with an error sigma_z=0.018. [Abridged]


title:
SPH simulations of Shakura-Sunyaev instability at intermediate accretion
  rates

abstract:
  We show that a standard Shakura-Sunyaev accretion disc around a black hole
with an accretion rate lower than the critical Eddington limit does show the
instability in the radiation pressure dominated zone. We obtain this result
performing time-dependent simulations of accretion disks for a set of values of
the viscosity parameter and accretion rate. In particular we always find the
occurrence of the collapse of the disc: the instability develops always towards
a collapsed gas pressure dominated disc and not towards the expansion. This
result is valid for all initial configurations we tested. We find significant
convective heat flux that increases the instability development time, but is
not strong enough to inhibit the disc collapse. A physical explanation of the
lack of the expansion phase is proposed considering the role of the radial heat
advection. Our finding is relevant since it excludes the formation of the hot
comptonizing corona -often suggested to be present- around the central object
by the mechanism of the Shakura-Sunyaev instability. We also show that, in the
parameters range we simulated, accretion disks are crossed by significant
amplitude acoustic waves.


title: The tidal perturbation of the low-mass globular cluster NGC 5466

abstract:
  The distribution of stars in the outer part of the sparse globular cluster
NGC 5466 provides evidence for possible tidal mass loss after a recent
disk-shock near the solar circle.


title:
Probing galaxy evolution through the internal colour gradients, the
  Kormendy relations and the Photometric Plane of cluster galaxies at z~0.2

abstract:
  We present a detailed analysis of the photometric properties of galaxies in
the cluster \A2163B at redshift z~0.2. R-, I- and K-band structural parameters,
(half light radius r_e, mean surface brightness <mi>_e within r_e and Sersic
index n) are derived for N~60 galaxies, and are used to study their internal
colour gradients. For the first time, we use the slopes of optical-NIR Kormendy
relations to study colour gradients as a function of galaxy size, and we derive
the Photometric Plane at z~0.2 in the K band. Colour gradients are negligible
at optical wavelengths, and are negative in the optical-NIR, implying a
metallicity gradient in galaxies of ~0.2 dex per radial decade. The analysis of
the Kormendy relation suggests that its slope increases from the optical to the
NIR, implying that colour gradients do not vary or even do become less steep in
more massive galaxies. Such a result is not simply accomodated within a
monolithic collapse scenario, while it can be well understood within a
hierarchical merging framework. Finally, we derive the first NIR Photometric
Plane at z~0.2, accounting for both the correlations on the measurement
uncertainties and the selection effects. The Photometric Plane at z~0.2 is
consistent with that at z~0, with an intrinsic scatter significantly smaller
than the Kormendy relation but larger than the Fundamental Plane.


title:
Indications for grain growth and mass decrease in cold dust disks around
  Classical T Tauri stars in the MBM 12 young association

abstract:
  We report detection of continuum emission at 850 and 450 micron from disks
around four Classical T Tauri stars in the MBM 12 (L1457) young association.
Using a simple model we infer masses of 0.0014-0.012 M_sun for the disk of LkHa
263 ABC, 0.005-0.021 M_sun for S18 ABab, 0.03-0.18 M_sun for LkHa 264 A, and
0.023-0.23 M_sun for LkHa 262. The disk mass found for LkHa 263 ABC is
consistent with the 0.0018 M_sun inferred from the scattered light image of the
edge-on disk around component C. Comparison to earlier 13CO line observations
indicates CO depletion by up to a factor 300 with respect to dark-cloud values.
The spectral energy distributions (SED) suggest grain growth, possibly to sizes
of a few hundred micron, but our spatially unresolved data cannot rule out
opacity as an explanation for the SED shape. Our observations show that these T
Tauri stars are still surrounded by significant reservoirs of cold material at
an age of 1-5 Myr. We conclude that the observed differences in disk mass are
likely explained by binary separation affecting the initial value. With
available accretion rate estimates we find that our data are consistent with
theoretical expectations for viscously evolving disks having decreased their
masses by ~30%.


title:
The cluster of galaxies A 2163B at z~0.2 II -- Colour gradients, re--mie
  relations and the Photometric Plane

abstract:
  This paper has been withdrawn by the author(s), since it has been merged with
paper I (astro-ph/0307482).


title: The Rise of High Energy Neutrino Astronomy at Horizon

abstract:
  High Energy Neutrino Astronomy energy windows may be ruled by a new Upward
and Horizontal Tau Air-Showers (UpTaus, HorTaus) detectors (scintillators and
optical arrays) located a few kilometers beyond facing High Mountains Chains,
or located above their top or flying on Planes, on Balloons and on Satellites
facing downward to the Earth Crust Horizon. While looking downward to the Earth
seeking for Upward and Horizontal Tau Air-Showers the same optical detectors
may often capture cosmic rays Cherenkov lights reflected or diffused by
downward Shower cosmic rays hitting the Earth soil (a sea,a lake, ice lands,
desert or ground). These new detectors may be built up as a circular hybrid
crown array at high quota facing to horizon in correlation with present largest
telescopes, like Magic or Shalon or ASHRA ones, if able to look below the Earth
edge. The UpTaus and HorTau Astronomy at 10^15 eV up to 10^19 eV energy windows
may test the largest primary neutrino fluxes in Z-Burst neutrino model needed
to solve the GZK puzzle or even the smaller but inevitable GZK neutrino flux
secondary of the same GZK cut-off. These HorTus signals might well be observed
in future EUSO experiment.


title: Broad redshifted line as a signature of outflow

abstract:
  We formulate and solve the diffusion problem of line photon propagation in a
bulk outflow from a compact object (black hole or neutron star) using a generic
assumption regarding the distribution of line photons within the outflow.
Thomson scattering of the line photons within the expanding flow leads to a
decrease of their energy which is of first order in v/c, where v is the outflow
velocity and c is the speed of light. We demonstrate that the emergent line
profile is closely related to the time distribution of photons diffusing
through the flow (the light curve) and consists of a broad redshifted feature.
We analyzed the line profiles for the general case of outflow density
distribution. We emphasize that the redshifted lines are intrinsic properties
of the powerful outflow that are supposed to be in many compact objects.


title:
A New Simple Model for High Frequency Quasi Periodic Oscillations in
  Black Hole Candidates

abstract:
  Observations of X-ray emissions from binary systems have long since been
considered important tools to test General Relativity in strong-field regimes.
The high frequency quasi-periodic oscillations (HFQPOs) observed in binaries
containing a black hole candidate, in particular, have been proposed as a means
to measure more directly the black hole properties such as its mass and spin.
Numerous models have been suggested to explain the HFQPOs and the rich
phenomenology accompanying them. Many of these models rest on a number of
assumptions and are at times in conflict with the most recent observations. We
here propose a new, simple model in which the HFQPOs result from basic $p$-mode
oscillations of a small accretion torus orbiting close to the black hole. We
show that within this model the key properties of the HFQPOs can be explained
simply, given a single reasonable assumption. We also discuss observational
tests that can falsify the model.


title:
Oscillations of vertically integrated relativistic tori -- I.
  Axisymmetric modes in a Schwarzschild spacetime

abstract:
  This is the first of a series of papers investigating the oscillation
properties of relativistic, non-selfgravitating tori orbiting around a black
hole. In this initial paper we consider the axisymmetric oscillation modes of a
torus constructed in a Schwarzschild spacetime. To simplify the treatment and
make it as analytical as possible, we build our tori with vertically integrated
and vertically averaged quantities. Our investigation progresses by steps. We
first consider a local analysis in Newtonian gravity and determine the
properties of acoustic wave propagation within these objects, as well as the
relations between acoustic and epicyclic oscillations. Next, we extend the
local analysis to a general relativistic framework. Finally, we perform a
global analysis and determine both the eigenfunctions and the eigenfrequencies
of the axisymmetric oscillations corresponding to the p modes of relativistic
tori. These behave as sound waves globally trapped in the torus and possess
eigenfrequencies appearing in the simple sequence 2:3:4:..., independently of
the distribution of angular momentum considered. The properties of the modes
investigated here are in good agreement with those observed in recent numerical
simulations and could have a number of different applications. In X-ray binary
systems containing a black hole candidate, for instance, p-mode oscillations
could be used to explain the harmonic relations in the high frequency
quasi-periodic oscillations observed. In systems comprising a massive torus
orbiting a black hole, on the other hand, p-mode oscillations could be used to
explain the development or the suppression of the runaway instability.


title: Detectability of Long GRB Afterglows from Very High Redshifts

abstract:
  Gamma-ray bursts are promising tools for tracing the formation of high
redshift stars, including the first generation. At very high redshifts the
reverse shock emission lasts longer in the observer frame, and its importance
for detection and analysis purposes relative to the forward shock increases. We
consider two different models for the GRB environment, based on current ideas
about the redshift dependence of gas properties in galaxies and primordial star
formation. We calculate the observed flux as a function of the redshift and
observer time for typical GRB afterglows, taking into account intergalactic
photoionization and Lyman-$\alpha$ absorption opacity as well as extinction by
the Milky Way Galaxy. The fluxes in the X-ray and near IR bands are compared
with the sensitivity of different detectors such as Chandra, XMM, Swift XRT and
JWST. Using standard assumptions, we find that Chandra, XMM and Swift XRT can
potentially detect GRBs in the X-ray band out to very high redshifts $z\gtrsim$
30. In the K and M bands, the JWST and ground-based telescopes are potentially
able to detect GRBs even one day after the trigger out to $z\sim$ 16 and 33, if
present. While the X-ray band is insensitive to the external density and to
reverse shocks, the near IR bands provide a sensitive tool for diagnosing both
the environment and the reverse shock component.


title: Star Formation Across the Taffy Bridge: UGC 12914/15

abstract:
  We present BIMA two-field mosaic CO(1-0) images of the Taffy galaxies (UGC
12914/15), which show the distinct taffy-like radio continuum emission bridging
the two spiral disks. Large amounts of molecular gas (1.4 x 10^{10} Msun, using
the standard Galactic CO-to-H$_2$ conversion applicable to Galactic disk giant
molecular clouds [GMCs]) were clearly detected throughout the taffy bridge
between the two galaxies, which, as in the more extreme case of HI, presumably
results from a head-on collision between the two galaxies. The highest CO
concentration between the two galaxies corresponds to the H_alpha source in the
taffy bridge near the intruder galaxy UGC 12915. This HII region is also
associated with the strongest source of radio continuum in the bridge, and
shows both morphological and kinematic connections to UGC 12915. The overall CO
distribution of the entire system agrees well with that of the radio continuum
emission, particularly in the taffy bridge. This argues for the star formation
origin of a significant portion of the radio continuum emission. Compared to
the HI morphology and kinematics, which are strongly distorted owing to the
high-speed collision, CO better defines the orbital geometry and impact
parameter of the interaction, as well as the disk properties (e.g., rotation,
orientation) of the progenitor galaxies. Based on the 20cm-to-CO ratio maps, we
conclude that the starburst sites are primarily located in UGC 12915 and the
H_alpha source in the bridge and show that the molecular gas in the taffy
bridge is forming into stars with star formation efficiency comparable to that
of the target galaxy UGC 12914 and similar to that in the Galactic disk.


title:
Using Fractal Dimensionality in the Search for Source Models of
  Ultra-High Energy Cosmic Rays

abstract:
  Although the existence of cosmic rays with energies extending well above
$10^{19}$ eV has been confirmed, their origin remains one of the most important
questions in astro-particle physics today. Several source models have been
proposed for the observed set of Ultra High Energy Cosmic Rays (UHECRs). Yet
none of these models have been conclusively identified as corresponding with
all of the available data. One possible way of achieving a global test of
anisotropy is through the measurement of the information dimension, $D_{\rm
I}$, of the arrival directions of a sample of events. $D_{\rm I}$ is a measure
of the intrinsic heterogeneity of a data sample. We will show how this method
can be used to take into account the extreme asymmetric angular resolution and
the highly irregular aperture of a monocular air-fluorescence detector. We will
then use a simulated, isotropic event sample to show how this method can be
used to place upper limits on any number of source models with no statistical
penalty.


title: Galactic Populations of Ultracompact Binaries

abstract:
  Recent RXTE and Chandra discoveries of low mass X-ray binaries with
ultra-short orbital periods have initiated theoretical work on the origins of
these peculiar systems. Using the StarTrack population synthesis code the
formation and evolution of X-ray ultracompact binaries (UCBs) in the Galactic
field are analyzed. The relative number of UCBs with a neutron star or a black
hole accretor populating our Galaxy is predicted. Our results demonstrate that
standard evolutionary scenarios involving primordial binaries can be sufficient
to produce the UCBs in the Galactic field without requiring additional
processes associated with the dense stellar environments in the cores of
globular clusters. In contrast to previous studies we find that the majority of
the immediate progenitors of these systems consist of a hydrogen exhausted
donor with an ONeMg white dwarf. The evolution of these systems leads to the
accretion induced collapse of the white dwarf to a neutron star, which can play
an important role in the formation of a majority of Galactic UCBs. We predict
that with an increase in the number of X-ray active UCBs hosting neutron stars
by an order of magnitude, a system with a black hole accretor may be found.


title:
The galactic center black hole as a possible retro-lens for the S2
  orbiting star

abstract:
  Holz & Wheeler (\cite{hw}) have recently proposed that a Schwarzschild black
hole may act as a retro-lens which, if illuminated by a powerful light source,
deflects light ray paths to large bending angles and a series of luminous arcs
(or rings in the case of aligned objects) centered on the black hole may form.
Obviously, the most convenient geometry to get retro-lensing images would be
that of a very bright star close to a massive black hole, say the putative
$\sim 4\times 10^6$ M$_{\odot}$ black hole at the galactic center. Recent
observations of the galactic center region in the $K$-band have revealed the
presence of a very bright main sequence star (labelled S2) with mass $\sim 15$
M$_{\odot}$ orbiting at close distance (130-1900 AU) from Sgr A$^*$. The
relatively vicinity of S2 to the central massive black hole may offer a unique
laboratory to test the formation of retro-lensing images. The next generation
of space-based telescopes in the $K$-band (like NGST) may have high enough
limiting magnitude necessary to observe such retro-lensing images.


title:
Vertical Structure Modeling of Saturn's Equatorial Region Using High
  Spectral Resolution Imaging

abstract:
  Saturn was observed on 6-11 February 2002 using an Acousto-optic Imaging
Spectrometer (AImS) to study Saturn's vertical cloud structure. The 3.67-m
Advanced Electro-Optical System telescope at the Maui Space Surveillance
Complex was used. The high spectral resolution and wide spectral coverage of
AImS (500 - 1000 nm) enabled us to sample the Saturnian atmosphere with high
vertical resolution and to derive the wavelength dependence of aerosol
properties. The model center-limb profiles were fit to the observed profiles in
the equatorial region. Adopting four different cloud models with three aerosol
phase functions, we varied up to nine free parameters to seek the best
solution. The results of the simultaneous fits to nine different profiles
around the 890-nm and 727-nm methane bands suggest that : 1) a cloud model
having higher aerosol density in the lower troposphere (0.15 - 1.5 bar) is
favorable, 2) the tropospheric cloud extends into the stratosphere, 3) the
wavelength dependence of the upper cloud optical thickness indicates that the
average aerosol size is larger than 0.7 - 0.8 micron, 4) the average aerosol
size of the upper tropospheric cloud increases with depth from about 0.15
micron to between 0.7--0.8 and 1.5 micron, 5) the aerosol properties in
February 2002 are similar to those observed during the 1990 equatorial
disturbance.


title: Gas in Dusty Debris Disks

abstract:
  The presence of gas in dusty debris disks around main-sequence stars is
reviewed. We present new observational results for the most prominent
representative of the class, viz. the southern naked-eye star beta Pictoris.
The spatial and spectral distribution of observed atomic lines from the disk
around the star is reproducable by a Keplerian rotation model to a high degree
of accuracy. The expected velocity dispersion due to radiation pressure in
resonance lines is not observed. Modeling the motion of different atomic
species under the influence of gravity, radiation pressure and gas friction
leads to the conclusion that an underlying decelerating component must be
present in the disk. This braking agent is most likely hydrogen, with inferred
average densities n(H) > 1e6 per cubic centimeter. This could support the
observational result of Thi et al. (2001) which indicated the presence of
appreciable amounts of H2 around the star beta Pic.


title: The luminosity function of Palomar 5 and its tidal tails

abstract:
  We present the main sequence luminosity function of the tidally disrupted
globular cluster Palomar 5 and its tidal tails. For this work we analyzed
imaging data obtained with the Wide Field Camera at the INT (La Palma) and data
from the Wide Field Imager at the MPG/ESO 2.2 m telescope at La Silla down to a
limiting magnitude of approximately 24.5 mag in B. Our results indicate that
preferentially fainter stars were removed from the cluster so that the LF of
the cluster's main body exhibits a significant degree of flattening compared to
other GCs. This is attributed to its advanced dynamical evolution. The LF of
the tails is, in turn, enhanced with faint, low-mass stars, which we interpret
as a consequence of mass segregation in the cluster.


title:
Curious Variables Experiment (CURVE). CCD Photometry of QW Serpentis in
  Superoutburst and Quiescence

abstract:
  We report extensive photometry of the dwarf nova QW Ser throughout its 2003
February superoutburst till quiescence. During the superoutburst the star
displayed clear superhumps with a mean period of Psh = 0.07703(4) days. In the
quiescence we observed a double humped wave characterized by a period of
P=0.07457(2) days. As both periods obey the Stolz-Schoembs relation with a
period excess equal to 3.30+/-0.06% the latter period is interpreted as the
orbital period of the binary system.


title: XMM-Newton search for hot gas in the dwarf galaxy IC 2574

abstract:
  We present an XMM-Newton observation of the nearby dwarf galaxy IC 2574. This
galaxy is part of our ensemble observed within a multi-frequency campaign to
study the physical conditions of the interstellar medium in dwarf galaxies in
general.
  Here, we focus on the diffuse soft (0.2 - 0.5 keV) X-ray emission associated
with IC 2574. Since this emission is expected to be quite faint we have to
reach the true X-ray background intensity level. For this aim, we have to
account for unrelated diffuse X-ray emission and for the vignetting of the
X-ray mirrors aboard the XMM-Newton satellite.


title: Gamma-Ray emission from Clusters of Galaxies

abstract:
  The nonthermal radiation observed from a handfull of clusters of galaxies
(CG) is the proof that particle acceleration occurs in the intracluster medium
(ICM). It is often believed that shock surfaces associated with either mergers
of CG, or with the cosmological inflow of matter onto clusters during structure
formation may be the sites for acceleration. We discuss here the effectiveness
of shock acceleration in the ICM, stressing that merger related shocks are
typically weak, at least for the so-called major mergers. We investigate the
implications of shock strenghts for gamma ray emission from single CG and for
their detectability with future gamma ray satellites (such as GLAST and AGILE)
and ground based Cherenkov telescopes. We also discuss the contribution of
clusters to the extragalactic diffuse gamma ray background (EDGRB).


title:
Interpenetrating plasma shells: near-equipartition magnetic field
  generation and non-thermal particle acceleration

abstract:
  We present the first three-dimensional fully kinetic electromagnetic
relativistic particle-in-cell simulations of the collision of two
interpenetrating plasma shells. The highly accurate plasma-kinetic
"particle-in-cell" (with the total of $10^8$ particles) parallel code OSIRIS
has been used. Our simulations show: (i) the generation of long-lived
near-equipartition (electro)magnetic fields, (ii) non-thermal particle
acceleration, and (iii) short-scale to long-scale magnetic field evolution, in
the collision region. Our results provide new insights into the magnetic field
generation and particle acceleration in relativistic and sub-relativistic
colliding streams of particles, which are present in gamma-ray bursters,
supernova remnants, relativistic jets, pulsar winds, etc..


title: The exosystems about HD169830 and HD12661: are they dynamical twins?

abstract:
  The new 2-planetary system around HD169830 has been announced during the
XIX-th IAP Colloquium "Extrasolar Planets: Today & Tomorrow" (Paris, June 30 -
July 4, 2003) by the Geneva Extrasolar Planet Search team. We study the orbital
dynamics of this system in the framework of the $N$-body problem. The analysis
of its orbital stability is performed using the long-term integrations and the
fast indicators, the Mean Exponential Growth factor of Nearby Orbits and the
Frequency Map Analysis. The HD169830 appears to be located in a wide stable
region of the phase space. The ratio of the mean motions of the planets
HD169830b and c is between low-order mean motion resonances, 9:1 and 10:1. The
long-term integration of the coplanar configurations, conducted over 1Gyr,
reveals that the eccentricities of the companions vary with a large amplitude
about 0.4-0.5 but there is no sign of instability. The orbital parameters of
the planets resemble those of another 2-planetary system, around HD12661. Both
of them can be classified as hierarchical planetary systems. We investigate
whether these two exosystems are dynamically similar. Such similarities may be
important for finding out if the formation and subsequent orbital evolution of
exoplanetary systems obey common rules.


title: Dual Cometary HII Regions in DR21: Bow Shocks or Champagne Flows?

abstract:
  The DR 21 massive star forming region contains two cometary HII regions,
aligned nearly perpendicular to each other on the sky. This offers a unique
opportunity to discriminate among models of cometary HII regions. We present
hydrogen recombination and ammonia line observations of DR 21 made with the
Very Large Array. The velocity of the molecular gas, measured from ammonia
emission and absorption lines, is constant to within +/- 1 km/s across the
region. However, the radial velocity of the ionized material, measured from
hydrogen recombination lines, differs by approximately 9 km/s between the
"heads" of the two cometary HII regions and by up to approximately 7 km/s from
that of the molecular gas. These findings indicate a supersonic velocity
difference between the compact heads of the cometary regions and between each
head and the ambient molecular material. This suggests that the observed
cometary morphologies are created largely by the motion of wind-blowing,
ionizing stars through the molecular cloud, as in a bow shock model.


title:
WIYN Open Cluster Study XVI: Optical/Infrared Photometry and Comparisons
  With Theoretical Isochrones

abstract:
  We present combined optical/near-IR photometry (BVIK) for six open clusters -
M35, M37, NGC 1817, NGC 2477, NGC 2420, and M67. The open clusters span an age
range from 150 Myr to 4 Gyr and have metal abundances from [Fe/H] = -0.3 to
+0.09 dex. We have utilized these data to test the robustness of theoretical
main sequences constructed by several groups as denoted by the following
designations - Padova, Baraffe, Y^2, Geneva, and Siess. The comparisons of the
models with the observations have been performed in the [Mv, (B-V)o], [Mv,
(V-I)o], and [Mv, (V-K)o] colour-magnitude diagrams as well as the
distance-independent [(V-K)o, (B-V)o] and [(V-K)o, (V-I)o] two-colour diagrams.
We conclude that none of the theoretical models reproduce the observational
data in a consistent manner over the magnitude and colour range of the
unevolved main sequence. In particular, there are significant zeropoint and
shape differences between the models and the observations. We speculate that
the crux of the problem lies in the precise mismatch between theoretical and
observational colour-temperature relations. These results underscore the
importance of pursuing the study of stellar structure and stellar modelling
with even greater intensity.


title:
Coronal element abundances of the post-common envelope binary V471 Tauri
  with ASCA

abstract:
  We report on ASCA observations of the coronally active companion star in the
post-common envelope binary V471 Tauri. Evolutionary calculations indicate that
there should be no peculiar abundances on the companion star resulting from the
common envelope epoch. Indeed, we find no evidence for peculiar abundances,
although uncertainties are high. We find that a single-temperature plasma model
does not fit the data. Two-temperature models with decoupled elemental
abundances suggest that Fe is underabundant compared to the Hyades photospheric
mean. In the absence of a measurement of photospheric Ne abundance in the
cluster, we find Ne is overabundant compared to the solar photospheric value.
This is indicative of the inverse first ionization potential effect.
Differences between coronal and photospheric abundances are believed to result
from the fractionation of ionized and neutral material in the upper atmosphere
of the star.


title:
Exploring Halo Substructure with Giant Stars: Spectroscopy of Stars in
  the Galactic Anticenter Stellar Structure

abstract:
  To determine the nature of the recently discovered, ring-like stellar
structure at the Galactic anticenter, we have collected spectra of a set of
presumed constituent M giants selected from the 2MASS point source catalog.
Radial velocities have been obtained for stars spanning ~100 degrees,
exhibiting a trend in velocity with Galactic longitude and an estimated
dispersion of 20 +/- 4 km/sec. A mean metallicity [Fe/H] = -0.4 +/- 0.3
measured for these stars combines with previous evidence from the literature to
suggest a population with a significant metallicity spread. In addition, a
curious alignment of at least four globular clusters of lower mean metallicity
is noted to be spatially and kinematically consistent with this stellar
distribution. We interpret the M giant sample position and velocity variation
with Galactic longitude as suggestive of a satellite galaxy currently
undergoing tidal disruption in a non-circular, prograde orbit about the Milky
Way.