title:
Global axisymmetric stability analysis for a composite system of two
  gravitationally coupled scale-free discs

abstract:
  In a composite system of gravitationally coupled stellar and gaseous discs,
we perform linear stability analysis for axisymmetric coplanar perturbations
using the two-fluid formalism. The background stellar and gaseous discs are
taken to be scale-free with all physical variables varying as powers of
cylindrical radius $r$ with compatible exponents. The unstable modes set in as
neutral modes or stationary perturbation configurations with angular frequency
$\omega=0$.


title: The Observation of Circumstellar Disks: Dust and Gas Components

abstract:
  Since the 1990's, protoplanetary disks and planetary disks have been
intensively observed from the optical to the millimetre wavelength and many
models have been developed to investigate their gas and dust properties and
dynamics. These studies remain empirical and rely on poor statistics with only
a few well known objects. However, the late phases of the stellar formation are
among the most critical for the formation of planetary systems. Therefore, we
believe it is timely to tentatively summarize the observed properties of
circumstellar disks around young stars from the protoplanetary to the planetary
phases. Our main concern is to present the physical properties considered as
observationally robust and to show their main physical differences associated
to an evolutionary scheme. We also describe areas still poorly understood such
as how protoplanetary disks disappear to lead to planetary disks and eventually
planets.


title: The Large Magellanic Cloud: Structure and Kinematics

abstract:
  I review our understanding of the structure and kinematics of the Large
Magellanic Cloud (LMC), with a particular focus on recent results. This is an
important topic, given the status of the LMC as a benchmark for studies of
microlensing, tidal interactions, stellar populations, and the extragalactic
distance scale. I address the observed morphology and kinematics of the LMC;
the angles under which we view the LMC disk; its in-plane and vertical
structure; the LMC self-lensing contribution to the total microlensing optical
depth; the LMC orbit around the Milky Way; and the origin and interpretation of
the Magellanic Stream. Our understanding of these topics is evolving rapidly,
in particular due to the many large photometric and kinematic datasets that
have become available in the last few years. It has now been established that:
the LMC is considerably elongated in its disk plane; the LMC disk is thicker
than previously believed; the LMC disk may have warps and twists; the LMC may
have a pressure-supported halo; the inner regions of the LMC show unexpected
complexities in their vertical structure; and precession and nutation of the
LMC disk plane contribute measurably to the observed line-of-sight velocity
field. However, many open questions remain and more work is needed before we
can expect to converge on a fully coherent structural, dynamical and
evolutionary picture that explains all observed features of the LMC.


title:
Pronounced long term flux variability of the Anomalous X-ray Pulsar
  1E1048.1-5937

abstract:
  We present XMM-Newton and Chandra observations of 1E1048.1-5937, being the
first to show evidence for a significant variation in the X-ray luminosity of
this Anomalous X-ray Pulsar (AXP). While during the first XMM-Newton (2000
December) and Chandra (2001 July) observations the source had a flux consistent
with that measured on previous occasions (~5x10e-12 ergs/cmq/s), two more
recent observations found it at a considerably higher flux level of 2x10e-11
ergs/cmq/s (2002 August; Chandra) and 10e-11 ergs/cmq/s (2003 June;
XMM-Newton). All the spectra are fit by the sum of a blackbody with kT~0.6 keV
and a power law with photon index ~3. No significant changes were seen in the
spectral parameters, while the pulsed fraction in the 0.6-10 keV energy range
decreased from ~90% in 2000 to ~53% in 2003. The spectral invariance does not
support the presence of two physically distinct components in the AXP emission.
The sparse coverage of the data does not permit us to unambiguously relate the
observed variations to the two bursts seen from this source in the fall of
2001.


title: XMM-Newton probes the stellar population in Cha I South

abstract:
  We report on a 30ksec XMM-Newton observation of the central region of the Cha
I star forming cloud. Virtually all known T Tauri star members and most of the
very-low mass objects including two bona-fide brown dwarfs (spectral types M7.5
and M8) are detected. We identify several new candidate members in the X-ray
image. Spectral analysis of the X-ray bright stars shows that previous X-ray
studies in Cha I have underestimated the X-ray luminosities, as a result of
simplified assumptions on the spectral shape. No dramatic changes in the
correlations of X-ray luminosity with age, effective temperature and mass are
seen at the substellar boundary, and the lowest-mass objects behave similar to
the higher-mass T Tauri stars in terms of variability. Thus the same dynamo
mechanism seems to operate in both low-mass stars and brown dwarfs, at least at
young ages. On the other hand, the only two A-type stars in the field show very
different X-ray properties, suggesting that various emission mechanisms may be
at work in intermediate-mass stars.


title: An Enlarged Cosmic Shear Survey with the William Herschel Telescope

abstract:
  We report the results of a cosmic shear survey using the 4.2m William
Herschel Telescope on La Palma, to a depth of R=25.8 (z~0.8), over 4 square
degrees. The shear correlation functions are measured on scales from 1' to 15',
and are used to constrain cosmological parameters. We ensure that our
measurements are free from instrumental systematics by performing a series of
tests, including a decomposition of the signal into E- and B-modes. We also
reanalyse the data independently, using the shear measurement pipeline
developed for the COMBO-17 survey. This confirms our results and also
highlights various effects introduced by different implementations of the basic
"KSB" shear measurement method. We find that the normalisation of the matter
power spectrum on 8 h^{-1}Mpc scales is
sigma_8=(1.02+/-0.15)(0.3/Omega_m)^{0.5}, where the 68%CL error includes noise,
sample variance, covariance between angular scales, systematic effects,
redshift uncertainty and marginalisation over other parameters. We compare
these results with other cosmic shear surveys and with recent constraints from
the WMAP experiment.


title:
Constraints from Gravitational Recoil on the Growth of Supermassive
  Black Holes at High Redshift

abstract:
  Recent studies have shown that during their coalescence, binary supermassive
black holes (SMBHs) experience a gravitational recoil with velocities of 100
km/s < v(kick) < 600 km/s. These velocities exceed the escape velocity v(esc)
from typical dark matter (DM) halos at high-redshift (z>6), and therefore put
constraints on scenarios in which early SMBHs grow at the centers of DM halos.
Here we quantify these constraints for the most distant known SMBHs, with
inferred masses in excess of 10^9 M(sun), powering the bright quasars
discovered in the Sloan Digital Sky Survey at z>6. We assume that these SMBHs
grew via a combination of accretion and mergers between pre-existing seed BHs
in individual progenitor halos, and that mergers between progenitors with
v(esc) < v(kick) disrupt the BH growth process. Our results suggest that under
these assumptions, the z=6 SMBHs had a phase during which gained mass
significantly more rapidly than under an Eddington-limited exponential growth
rate.


title: Hubble Space Telescope Imaging of the WR 38/WR38a Cluster

abstract:
  We are conducting a high angular resolution imaging survey of Galactic
Wolf-Rayet stars using the Wide Field and Planetary Camera 2 aboard the Hubble
Space Telescope. We have found a small stellar cluster associated with the
faint, close pair WR 38 and WR 38a. We present astrometric measurements and
photometry in the wide-band F336W (U), F439W (B), and F555W (V) filter system
for these cluster and nearby stars. We compare their colors and magnitudes with
calibrated model results for reddened stars to identify seven probable main
sequence members of the cluster. A least-squares fit of the colors and
magnitudes of this set yields a cluster reddening of E(B-V) = 1.45 +/- 0.14 mag
and a distance of 3.7^{+3.8}_{-1.2} kpc. We discuss the relationship of this
cluster to other objects along the line of sight, and we argue that the
distance probably lies in the range 5 - 8 kpc (but is not as great as 14.5 kpc
distance recently advocated by Shorlin, Turner, & Pedreros). At a distance of 8
kpc, the cluster would reside in a dense region of the Carina spiral arm, close
to a giant molecular cloud and the starburst cluster NGC 3603.


title:
The Sensitivity of Infall Molecular Line Profiles to the Ambient
  Radiation Field

abstract:
  In cold molecular clouds submillimetre emission lines are excited by the
ambient radiation field. The pumping is dominated by the cosmic microwave
background (CMB). It is usual in molecular line radiative transfer modelling to
simply assume that this is the only incident radiation field. In this paper, a
molecular line transport code and a dust radiative transfer code are used to
explore the effects of the inclusion of a full interstellar radiation field
(ISRF) on a simple test molecular cloud. It is found that in many galactic
situations, the shape and strength of the line profiles that result are robust
to variations in the ISRF and thus that in most cases, it is safe to adopt the
CMB radiation field for the molecular line transport calculations. However, we
show that in two examples, the inclusion of a plausible radiation field can
have a significant effect on the the line profiles. Firstly, in the vicinity of
an embedded massive star, there will be an enhanced far infared component to
the radiation field. Secondly, for molecular clouds at large redshift, the CMB
temperature increases and this of course also alters the radiation field. In
both of these cases, the line profiles are weakened significantly compared to a
cloud exposed to a standard radiation field. Therefore this effect should be
accounted for when investigating prestellar cores in massive star forming
regions and when searching for molecular clouds at high redshift.


title: Multi-Color Photometry of the 2001 Superoutburst of WZ sagittae

abstract:
  We present the results of U-band and multi-color photometry during the 2001
superoutburst of WZ Sagittae. Our 10 nights of U-band photometry span the time
interval from HJD 2452118 to 2452197 while our multi-color observations range
from HJD 2452115 to 2452197. The U-band light curves are generally in agreement
with other datasets obtained during the superoutburst showing highly modulated
light early on, rebrightenings, and superhumps of similar shape and period
(except during the rebrightening peak). One of our multi-color datasets
fortuitously covers the first rebrightening and allows determination of the
accretion disk color temperature before, during, and after the event. It is
seen that the rebrightening is a change from a neutral disk (T~7000K) to an
ionized disk (T$\sim$10000K) and back again. We develop a simple limit cycle
model for this behavior which approximately predicts the semi-periodic
timescale observed for the rebrightenings. We discuss our results in relation
to accretion disk structure during superoutburst.


title:
Correcting the chromatic and airmass dependent extinction for TIMMI2
  spectra

abstract:
  We present a method to correct the chromatic and airmass dependent extinction
for N-band spectra taken with the TIMMI2 instrument at the ESO / La Silla
observatory. Usually, the target and calibrator star have to be observed at
similar airmass in order to obtain reliable spectrophotometric fluxes. Our
method allows to correct the atmospheric extinction and substantially improves
the spectrophotometric flux calibration, when the standard stars were observed
at a very different airmass than the targets. Hundreds of standard star
measurements in several passbands (N1, N8.9, N10.4, N11.9) were used to derive
mid-IR extinction coefficients. We demonstrate that applying our correction of
the differential extinction to test data results in a spectrophotometric
accuracy up to 2% within the literature flux.


title:
Accelerating universe from gravitational leakage into extra dimensions:
  confrontation with SNeIa

abstract:
  There is mounting observational evidence that the expansion of our universe
is undergoing an acceleration. A dark energy component has usually been invoked
as the most feasible mechanism for the acceleration. However, it is desirable
to explore alternative possibilities motivated by particle physics before
adopting such an untested entity. In this work, we focus our attention on an
acceleration mechanism: one arising from gravitational leakage into extra
dimensions. We confront this scenario with high-$z$ type Ia supernovae compiled
by Tonry et al. (2003) and recent measurements of the X-ray gas mass fractions
in clusters of galaxies published by Allen et al. (2002,2003). A combination of
the two databases gives at a 99% confidence level that
$\Omega_m=0.29^{+0.04}_{-0.02}$, $\Omega_{rc}=0.21^{+0.08}_{-0.08}$, and
$\Omega_k=-0.36^{+0.31}_{-0.35}$, indicating a closed universe. We then
constrain the model using the test of the turnaround redshift, $z_{q=0}$, at
which the universe switches from deceleration to acceleration. We show that, in
order to explain that acceleration happened earlier than $z_{q=0} = 0.6$ within
the framework of gravitational leakage into extra dimensions, a low matter
density, $\Omega_m < 0.27$, or a closed universe is necessary.


title: A new alternative model to dark energy

abstract:
  The recent observations of type Ia supernovae strongly support that the
universe is accelerating now and decelerated in the recent past. This may be
the evidence of the breakdown of the standard Friedmann equation. Instead of a
linear function of the matter density, we consider a general function of the
matter density to modify the Freidmann equation. We propose a new model which
explains the recent acceleration and the past deceleration. Furthermore, the
new model also gives a decelerated universe in the future. The new model gives
$\Omega_{m0}=0.46$ and $z_T=0.44$.


title:
Direct evidence of efficient cosmic ray acceleration and magnetic field
  amplification in Cassiopeia A

abstract:
  It is shown that the nonlinear kinetic theory of cosmic ray (CR) acceleration
in supernova remnants (SNRs) describes the shell-type nonthermal X-ray
morphology of Cas A, obtained in Chandra observations, in a satisfactory way.
The set of empirical parameters, like distance, source size and total energy
release, is the same which reproduces the dynamical properties of the SNR and
the spectral characteristics of the emission produced by CRs. The extremely
small spatial scales in the observed morphological structures at hard X-ray
energies are due to a large effective magnetic field $B_d \sim 500$ $\mu$G in
the interior which is at the same time not only required but also sufficient to
achieve the excellent agreement between the spatially integrated radio and
X-ray synchrotron spectra and their calculated form. The only reasonably
thinkable condition for the production of such a large effective field strength
is a very efficiently accelerated nuclear CR component. Therefore the Chandra
data confirm first of all the inference that Cas A indeed accelerates nuclear
CRs with the high efficiency required for Cas A to be considered as a member of
the main class of Galactic CR sources and, secondly, that the nonlinear kinetic
theory of CR acceleration in SNRs is a reliable method to determine the
magnetic field value in SNRs.


title: Holography and Variable Cosmological Constant

abstract:
  An effective local quantum field theory with UV and IR cutoffs correlated in
accordance with holographic entropy bounds is capable of rendering the
cosmological constant (CC) stable against quantum corrections. By setting an IR
cutoff to length scales relevant to cosmology, one easily obtains the currently
observed rho_Lambda ~ 10^{-47} GeV^4, thus alleviating the CC problem. It is
argued that scaling behavior of the CC in these scenarios implies an
interaction of the CC with matter sector or a time-dependent gravitational
constant, to accommodate the observational data.


title: Have Atmospheric Cerenkov Telescopes Observed Dark Matter?

abstract:
  Two ground-based experiments have recently independently detected TeV
$\gamma$-rays from the direction of the Galactic center. The observations made
by the VERITAS and CANGAROO collaborations are unexpected, although not
impossible to interpret in terms of astrophysical sources. Here we examine in
detail whether the observed $\gamma$-rays may arise from the more exotic
alternative of annihilations of dark matter particles clustered in the center
of the Galaxy.


title:
Testing the cosmological principle of isotropy: local power spectrum
  estimates of the WMAP data

abstract:
  We apply the Gabor transform methodology proposed in (Hansen et al. 2002,
2003) to the WMAP data in order to test the statistical properties of the CMB
fluctuation field and specifically to evaluate the fundamental assumption of
cosmological isotropy. We estimate the angular power spectrum locally in discs
of various sizes positioned in different directions. We determine whether the
spatial position of a few outliers in the angular power spectrum could suggest
the presence of residual foregrounds or systematic effects. For multipoles
close to the first peak, the most deviant local estimates from the best fit
WMAP model are associated with a few particular areas close to the Galactic
plane. Such deviations also include the ``dent'' in the spectrum just shortward
of the first peak which was remarked upon by the WMAP team. Estimating the
angular power spectrum excluding these areas gives a slightly higher first
Doppler peak amplitude. Finally, we probe the isotropy of the largest angular
scales by estimating the power spectrum on hemispheres and reconfirm strong
indications of a north-south asymmetry previously reported by other authors. We
find tentative evidence for residual foregrounds in the range l=2-4, which
could be associated with the low measured quadrupole amplitudes and other
anomalies on these angular scales. However, over the range l=5-40 the observed
asymmetry is much harder to explain in terms of residual foregrounds and known
systematic effects. Such asymmetric distributions of power on the sky provide a
serious test for the cosmological principle of isotropy.


title: Supernovae Light Curves: An Argument for a New Distance Modulus

abstract:
  Supernovae Ia (SNe Ia) light curves have been used to prove the universe is
expanding. As standard candles, SNe Ia appear to indicate the rate of expansion
has increased in the past and is now decreasing. This independent evaluation of
SNe Ia light curves demonstrates a Malmquist Type II bias exists in the body of
supernova data. If this bias is properly addressed, there is very little budget
for time dilation in the light curves of supernova. A non-relativistic distance
modulus is proposed, which is based on the predictable attenuation of light by
an intergalactic CREIL (Coherent Raman Effects on Incoherent Light) radiation
transfer functions.


title: BL Lac evolution revisited

abstract:
  BL Lac objects are an elusive and rare class of active galactic nuclei. For
years their evolutionary behavior has appeared inconsistent with the trend
observed in the population of AGN at large. The so-called ``negative''
evolution implies that BL Lacs were either less or fainter in the past. This
effect is stronger for BL Lacs selected in X-ray surveys. We have investigated
if one of the selection criteria, namely the flat-radio spectrum (imposed on
the Radio-selected but not on the X-ray-selected samples), might explain the
different evolutionary trend.


title:
Multifluid, Magnetohydrodynamic Shock Waves with Grain Dynamics II. Dust
  and the Critical Speed for C Shocks

abstract:
  This is the second in a series of papers on the effects of dust on
multifluid, MHD shock waves in weakly ionized molecular gas. We investigate the
influence of dust on the critical shock speed, v_crit, above which C shocks
cease to exist. Chernoff showed that v_crit cannot exceed the grain
magnetosound speed, v_gms, if dust grains are dynamically well coupled to the
magnetic field. We present numerical simulations of steady shocks where the
grains may be well- or poorly coupled to the field. We use a time-dependent,
multifluid MHD code that models the plasma as a system of interacting fluids:
neutral particles, ions, electrons, and various ``dust fluids'' comprised of
grains with different sizes and charges. Our simulations include grain inertia
and grain charge fluctuations but to highlight the essential physics we assume
adiabatic flow, single-size grains, and neglect the effects of chemistry. We
show that the existence of a phase speed v_phi does not necessarily mean that C
shocks will form for all shock speeds v_s less than v_phi. When the grains are
weakly coupled to the field, steady, adiabatic shocks resemble shocks with no
dust: the transition to J type flow occurs at v_crit = 2.76 v_nA, where v_nA is
the neutral Alfven speed, and steady shocks with v_s > 2.76 v_nA are J shocks
with magnetic precursors in the ion-electron fluid. When the grains are
strongly coupled to the field, v_crit = min(2.76 v_nA, v_gms). Shocks with
v_crit < v_s < v_gms have magnetic precursors in the ion-electron-dust fluid.
Shocks with v_s > v_gms have no magnetic precursor in any fluid. We present
time-dependent calculations to study the formation of steady multifluid shocks.
The dynamics differ qualitatively depending on whether or not the grains and
field are well coupled.


title: The role of bars

abstract:
  Secular evolution and fueling is driven by bars in spiral galaxies, and the
related dynamical processes are reviewed. It is shown that gravity torques
dominate over viscous torques, and produce gas infall to the center. In this
infall, the bar wave accepts the angular momentum, which produces its
destruction. In the end, a central mass concentration is build, which also
contributes to this destruction. While gas can be stalled at ILR for a while,
secondary bars then take over the fueling. In a galaxy life-time, several bar
episodes can successively develop. Through external gas accretion, disks are
replenished by intermittence, between two bar phases. While the general trend
for a galaxy is to evolve towards early-types, its morphology can oscillate,
and turn back transiently to later-types.


title:
Predicting Planets in Known Extra-Solar Planetary Systems II: Testing
  for Saturn-mass Planets

abstract:
  Recent results have shown that many of the known extrasolar planetary systems
contain regions which are stable for massless test particles. We examine the
possibility that Saturn-mass planets exist in these systems, just below the
detection threshold, and attempt to predict likely orbital parameters for such
unseen planets. To do this, we insert a Saturn-mass planet into the stable
regions of these systems and integrate its orbit for 100 million years. We
conduct 200-600 of these experiments to test parameter space in HD37124,
HD38529, 55Cnc, and HD74156. In HD37124 the global maximum of the survival rate
of Saturns in parameter space is at semimajor axis a = 1.03 AU, eccentricity
e=0.1. In HD38529, only 5% of Saturns are unstable, and the region in which a
Saturn could survive is very broad, centered on 0.5<a<0.6, e<0.2. In 55Cnc we
find three maxima at (a,e) = (1.0 AU, 0.02), (2.0 AU, 0.08), and (3.0 AU,
0.17). In HD74156 we find a broad maximum with $a$ = 0.9-1.2 AU, e<=0.15.
Several of these maxima are located in the habitable zones of their parent
stars and are therefore of astrobiological interest. We suggest the possibility
that companions may lie in these locations of parameter space, and encourage
further observational investigation of these systems.


title:
Predicting Planets in Known Extra-Solar Planetary Systems III: Forming
  Terrestrial Planets

abstract:
  Recent results have shown that many of the known extrasolar planetary systems
contain regions which are stable for both Earth-mass and Saturn-mass planets.
Here we simulate the formation of terrestrial planets in four planetary systems
-- 55 Cancri, HD 38529, HD 37124, and HD 74156 -- under the assumption that
these systems of giant planets are complete and that their orbits are
well-determined. Assuming the giant planets formed and migrated quickly, then
terrestrial planets may form from a second generation of planetesimals. In each
case, Moon- to Mars-sized planetary embryos are placed in between the giant
planets and evolved for 100 Myr. We find that planets form relatively easily in
55 Cnc, with masses up to 0.6 Earth masses and in some cases substantial water
contents and orbits in the habitable zone. HD 38529 is likely to support an
asteroid belt but no terrestrial planets of significant mass. No terrestrial
planets form in HD 37124 and HD 74156, although in some cases 1-2 lone embryos
survive for 100 Myr. If migration occurred later, depleting the planetesimal
disk, then massive terrestrial planets are unlikely to form in any of these
systems.


title:
A 20-cm Survey for Pulsars in Globular Clusters using the GBT and
  Arecibo

abstract:
  We have been conducting deep searches at ~20 cm of >30 globular clusters
(GCs) using the 305-m Arecibo telescope in Puerto Rico and the 100-m Green Bank
telescope (GBT) in West Virginia. With roughly 80% of our search data analyzed,
we have confirmed 13 new millisecond pulsars (MSPs), 12 of which are in binary
systems, and at least three of which eclipse. We currently have timing
solutions for five of these systems and basic orbital and spin parameters for
six others.


title: Spreading of Accreted Material on White Dwarfs

abstract:
  When a white dwarf (WD) is weakly magnetized and its accretion disk is thin,
accreted material first reaches the WD's surface at its equator. This matter
slows its orbit as it comes into co-rotation with the WD, dissipating kinetic
energy into thermal energy and creating a hot band of freshly accreted material
around the equator. Radiating in the extreme ultraviolet and soft X-rays, this
material moves toward the pole as new material piles behind it, eventually
becoming part of the WD once it has a temperature and rotational velocity
comparable with the surface. We present a set of solutions which describe the
properties of this ``spreading layer'' in the steady state limit based on the
conservation equations derived by Inogamov & Sunyaev (1999) for accreting
neutron stars. Our analysis and subsequent solutions show that the case of WDs
is qualitatively different. We investigate example solutions of the spreading
layer for a WD of mass $M=0.6M_\odot$ and radius $R=9\times10^{8}{\rm cm}$.
These solutions show that the spreading layer typically extends to an angle of
$\theta_{\rm SL}\approx0.01-0.1$ (with respect to the equator), depending on
accretion rate and the magnitude of the viscosity. At low accretion rates,
$\dot{M}\lesssim10^{18}{\rm g s}^{-1}$, the amount of spreading is negligible
and most of the dissipated energy is radiated back into the accretion disk.
When the accretion rate is high, such as in dwarf novae, symbiotic binaries,
and supersoft sources, the material may spread to latitudes high enough to be
directly visible above the accretion disk.


title:
Modeling the submillimeter emission from the Cepheus A young stellar
  cluster: Evidence for large scale collapse

abstract:
  Evidence for a large scale flow of low density gas onto the Cepheus A young
stellar cluster is presented. Observations of K-band near-infrared and
multi-transition CS and N2H+ millimeter line emission are shown in relation to
a sub-millimeter map of the cool dust around the most embedded stars. The
near-infrared emission is offset from the dust peak suggesting a shift in the
location of star formation over the history of the core. The CS emission is
concentrated toward the core center but N2H+ peaks in two main cores offset
from the center, opposite to the chemistry observed in low mass cores. A
starless core with strong CS but weak N2H+ emission is found toward the western
edge of the region. The average CS(2-1) spectrum over the cluster forming core
is asymmetrically self-absorbed suggesting infall. We analyze the large scale
dynamics by applying a one-dimensional radiative transfer code to a model
spherical core with constant temperature and linewidth, and a density profile
measured from an archival 850 micron map of the region. The best fit model that
matches the three CS profiles requires a low CS abundance in the core and an
outer, infalling envelope with a low density and undepleted CS abundance. The
integrated intensities of the two N2H+ lines is well matched with a constant
N2H+ abundance. The envelope infall velocity is tightly constrained by the
CS(2-1) asymmetry and is sub-sonic but the size of the infalling region is
poorly determined. The picture of a high density center with depleted CS slowly
accreting a low density outer envelope with normal CS abundance suggests that
core growth occurs at least partially by the dissipation of turbulent support
on large scales.


title: Unraveling the drift behaviour of the remarkable pulsar PSR B0826-34

abstract:
  We present new results from high sensitivity GMRT observations of PSR
B0826-34. We provide a model to explain the observed subpulse drift properties
of this pulsar, including the apparent reversals of the drift direction. In
this model, PSR B0826-34 is close to being an aligned rotator. We solve for the
emission geometry of this pulsar and show that the angle between the rotation
and the magnetic axes is less than 5 deg. We see evidence for as many as 6 to 7
drifting bands in the main pulse at 318 MHz, which are part of a circulating
system of about 15 spark-associated subpulse emission beams. We provide
quantitative treatments of the aliasing problem and various effects of
geometry. The observed drift rate is an aliased version of the true drift rate,
such that a subpulse drifts to the location of the adjacent subpulse (or a
multiple thereof) in about one pulsar period. We show that small variations, of
the order of 3-8%, in the mean drift rate are then enough to explain the
apparent reversals of drift direction. We find the mean circulation time of the
drift pattern to be significantly longer than the predictions of the original
RS75 model and propose an explanation for this, based on modified models with
temperature regulated partial ion flow in the polar vacuum gap. From the
variation of the mean subpulse separation across the main pulse window, we show
that the spark pattern is not centred around the dipole axis, but around a
point much closer (within a degree or so) to the rotation axis -- we discuss
the implication of this.


title: Quasi-hydrostatic intracluster gas under radiative cooling

abstract:
  Quasi-hydrostatic cooling of the intracluster gas is studied. In the
quasi-hydrostatic model, work done by gravity on the inflow gas with dP \neq 0,
where P is the gas pressure, is taken into account in the thermal balance. The
gas flows in from the outer part so as to compensate the pressure loss of the
gas undergoing radiative cooling, but the mass flow is so moderate and smooth
that the gas is considered to be quasi-hydrostatic. The temperature of the
cooling gas decreases toward the cluster center, but, unlike cooling flows with
dP = 0, approaches a constant temperature of \sim 1/3 the temperature of the
non-cooling ambient gas. This does not mean that gravitational work cancels out
radiative cooling, but means that the temperature of the cooling gas appears to
approach a constant value toward the cluster center if the gas maintains the
quasi-hydrostatic balance. We discuss the mass flow in quasi-hydrostatic
cooling, and compare it with the standard isobaric cooling flow model. We also
discuss the implication of \dot{M} for the standard cooling flow model.


title:
Prospect of determining the Dirac/Majorana state of neutrino by
  Multi-OWL experiment

abstract:
  We consider the non-radiative two body decay of a neutrino to a daughter
neutrino with degraded energy and a very light particle (Majoron). Ultrahigh
energy neutrinos from an astrophysical source like a Gamma Ray Burst undergoing
this decay process are found to produce different number of events in the
detector depending on whether they are Majorana or Dirac particles. The next
generation large scale experiments like Multi-OWL is expected to provide us an
accurate determination of the flux of neutrinos from astrophysical sources and
this may enable us to distinguish between the Dirac and Majorana nature of
neutrino.


title:
Kinematics of the chromospherically active binaries and evidence of an
  orbital period decrease in binary evolution

abstract:
  Kinematics of 237 Chromospherically Active Binaries (CAB) were studied. The
sample is heterogeneous with different orbits and physically different
components from F to M spectral type main sequence stars to G and K giants and
super giants. The computed $U$, $V$, $W$ space velocities indicate the sample
is also heterogeneous in the velocity space. That is, both kinematically
younger and older systems exist among the non-evolved main sequence and the
evolved binaries containing giants and sub giants. The kinematically young
(0.95 Gyr) sub-sample (N=95), which is formed according to the kinematical
criteria of moving groups, was compared to the rest (N=142) of the sample (3.86
Gyr) in order to investigate observational clues of the binary evolution.
Comparing the orbital period histograms between the younger and older
sub-samples, evidences were found supporting Demircan's (1999) finding that the
CAB binaries lose mass (and angular momentum) and evolve towards shorter
orbital periods. The evidence of mass loss is noticeable on the histograms of
the total mass ($M_{h}+M_{c}$), which is compared between the younger
(available only N=53 systems) and older sub-samples (available only N=66
systems). The orbital period decrease during binary evolution is found to be
clearly indicated by the kinematical ages of 6.69, 5.19, and 3.02 Gyr which
were found in the sub samples according to the period ranges of $logP\leq0.8$,
$0.8<logP\leq1.7$, and $1.7<logP\leq3$ among the binaries in the older sub
sample.


title: Bayesian Hypothesis Testing for Planet Detection

abstract:
  The past five years has seen a surge in research and innovative ideas for the
imaging of extrasolar planets, particular terrestrial ones. We expect that
within the next decade a space observatory will be launched with the objective
of imaging earthlike planets. Because of the limited lifetime of such a mission
and the large number of potential targets, integration time is a critical
parameter. In fact, integration time is the primary metric in evaluating
various design approaches for the high contrast imaging system. In this paper
we present a new approach to determining the existence of a planet in an
observed system using Bayesian hypothesis testing. Rather than perform
photometry, or rely on vision to determine the existence of a planet, this
approach evaluates the image plane data statistically under certain assumptions
about the prior probability distributions. We show that extremely high
confidence can be achieved in substantially shorter integration times than
conventional photometric methods.


title: The spatial energy spectrum of magnetic fields in our Galaxy

abstract:
  Interstellar magnetic fields exist over a broad range of spatial scales,
extending from the large Galactic scales ($\sim 10$ kpc) down to the very small
dissipative scales ($\ll 1$ pc). In this paper, we use a set of 490 pulsars
distributed over roughly one third of the Galactic disk out to a radius $R
\simeq 10$ kpc (assuming $R_\odot = 8.5$ kpc) and combine their observed
rotation and dispersion measures with their estimated distances to derive the
spatial energy spectrum of the Galactic interstellar magnetic field over the
scale range $0.5 - 15$ kpc. We obtain a nearly flat spectrum, with a 1D
power-law index $\alpha=-0.37\pm0.10$ for $E_{\rm B}(k)=C k^{\alpha}$ and an
rms field strength of approximately $6 \mu$G over the relevant scales. Our
study complements the derivation of the magnetic energy spectrum over the scale
range $0.03 - 100$ pc by \citet{ms96b}, showing that the magnetic spectrum
becomes flatter at larger scales. This observational result is discussed in the
framework of current theoretical and numerical models.


title:
$\Delta\alpha/\alpha$ from QSO absorption lines driven by an oscillating
  scalar field

abstract:
  The new result on the QSO absorption lines from VLT-UVES sample is compared
with the past reports on the time-variability of the fine-structure "constant"
derived from the Keck/HIRES observation, on the basis of an oscillatory
behavior of the scalar field supposed to be responsible for the cosmological
acceleration.


title: Discovery of three optical open clusters in the Galaxy

abstract:
  We report the discovery of three optical open clusters in the Milky Way. Two
clusters are in Scutum (Cluster1 at l=18.44 degrees and b=-0.42 degrees, and
Cluster2 at l=19.60 degrees and b=-1.02 degrees), thus projected not far from
the Galactic center direction, and the other is in Canis Major (Cluster3 at
l=235.61 degrees and b=-4.10 degrees), near the anti-center direction. Cluster3
is less populous than Clusters 1 and 2, but presents evidence of being a
physical system. The objects were found optically by inspecting maps obtained
from the Guide Star Catalogue and images from the Digitized Sky Survey. No
previous identification of cluster has been reported in each area so far. The
analysis was carried out with 2MASS photometry in J and H. For Cluster1 we
derive an age of 25 Myr, a reddening E(B-V)=2.18 and a distance from the Sun
1.64kpc; for Cluster2, age of 500Myr, E(B-V)=0.91 and distance 2.19kpc; finally
for Cluster3, age 32-100Myr, E(B-V)=0.94 and distance of 3.93kpc. Luminosity
and mass functions are derived for Clusters1 and 2 which, in turn, allowed us
to estimate their observed masses as 147 and 89 solar masses, respectively.
Estimated total masses, by extrapolating the mass functions to 0.08 solar mass,
amount to 382 and 614 solar masses, for the two clusters. Cluster3 has an
observed mass of 55 solar masses. The present results indicate that further
searches in the optical might still reveal new open clusters, and more so in
infrared bands.


title: Dark Energy Constraints from the Cosmic Age and Supernova

abstract:
  Using the low limit of cosmic ages from globular cluster and the white
dwarfs: $t_0 > 12$Gyr, together with recent new high redshift supernova
observations from the HST/GOODS program and previous supernova data, we give a
considerable estimation of the equation of state for dark energy, with uniform
priors as weak as $0.2<\Omega_m<0.4$ or $0.1<\Omega_m h^2<0.16$. We find cosmic
age limit plays a significant role in lowering the upper bound on the variation
amplitude of dark energy equation of state. We propose in this paper a new
scenario of dark energy dubbed Quintom, which gives rise to the equation of
state larger than -1 in the past and less than -1 today, satisfying current
observations. In addition we've also considered the implications of recent
X-ray gas mass fraction data on dark energy, which favors a negative running of
the equation of state.


title: Attractor Behavior of Phantom Cosmology

abstract:
  We investigate the cosmological attractor of the minimally coupled,
self-interacting phantom field with a positive energy density but negative
pressure. It is proved that the phantom cosmology is rigid in the sense that
there exists a unique attractor solution. We plot the trajectories in the phase
space numerically for the phantom field with three typical potentials. Phase
portraits indicate that an initial kinetic term decays rapidly and the
trajectories reach the unique attractor curve. We find that the curve
corresponds to the slow-climb solution.


title:
Optical and Near-Infrared Color Profiles in Nearby Early-Type Galaxies
  and The Implied Age and Metallicity Gradients

abstract:
  We present results of age and metallicity gradient analysis inferred from
both optical and near-infrared surface photometry. The analysis is based on a
sample of 36 nearby early-type galaxies, obtained from the Early Data Release
of the Sloan Digital Sky Survey and the Two Micron All Sky Survey. Surface
brightness profiles were derived in each band, and used to study the color
gradients of the galaxies. Using simple stellar population models with both
optical and near infrared colors, we may interpret the color gradients in term
of age and metallicity gradients of galaxies. Using $g_Z \equiv d \log Z_{\rm
met} / d \log R $ and $g_A = d \log {\rm Age} / d \log R $ to represent the
metallicity and age gradients, we found a median value of $g_Z=-0.25\pm 0.03$
for the metallicity gradient, with a dispersion $\sigma_{g_Z}=0.19\pm0.02$. The
corresponding values for the age gradient were $g_A=0.02\pm 0.04$ and
$\sigma_{g_A}=0.25\pm0.03$. These results are in good agreement with recent
observational results, as well as with recent simulations that suggest both
monolithic collapse and major merger have played important roles in the
formation of early-type galaxies. Our results demonstrate the potential of
using multi-waveband colors obtained from current and future optical and
infrared surveys in constraining the age and metallicity gradients of
early-type galaxies.


title: Lyman Break Galaxies at $z\sim5$: Rest-Frame UV Spectra

abstract:
  We report initial results for spectroscopic observations of candidates of
Lyman Break Galaxies (LBGs) at $z\sim5$ in a region centered on the Hubble Deep
Field-North by using the Faint Object Camera and Spectrograph attached to the
Subaru Telescope. Eight objects with $I_C\leq25.0$ mag, including one AGN, are
confirmed to be at $4.5<z<5.2$. The rest-frame UV spectra of seven LBGs
commonly show no or weak Lyalpha emission line (rest-frame equivalent width of
0-10\AA) and relatively strong low-ionization interstellar metal absorption
lines of SiII $\lambda$1260, OI+SiII $\lambda$1303, and CII $\lambda$1334 (mean
rest-frame equivalent widths of them are $-1.2 \sim -5.1 $\AA). These
properties are significantly different from those of the mean rest-frame UV
spectrum of LBGs at $z\sim3$, but are quite similar to those of subgroups of
LBGs at $z\sim3$ with no or weak Lyalpha emission. The weakness of Lyalpha
emission and strong low-ionization interstellar metal absorption lines may
indicate that these LBGs at $z\sim5$ are chemically evolved to some degree and
have a dusty environment. Since the fraction of such LBGs at $z\sim5$ in our
sample is larger than that at $z\sim3$, we may witness some sign of evolution
of LBGs from $z\sim5$ to $z\sim3$, though the present sample size is very
small. It is also possible, however, that the brighter LBGs tend to show no or
weak Lyalpha emission, because our spectroscopic sample is bright (brighter
than $L^{\ast}$) among LBGs at $z\sim5$. More observations are required to
establish spectroscopic nature of LBGs at $z\sim5$.


title:
Gauge-Invariant Gravitational Wave Extraction from Coalescing Binary
  Neutron Stars

abstract:
  We report application of a method for extracting gravitational waves to
three-dimensional numerical simulation on coalescing binary neutron stars. We
found the extracted wave form includes the componets corresponding to the
quadrupole part in the Newtonian potential of the background metric, if it is
monitored at a position not far from the central stars. We present how to
eliminate it.


title: The Holographic Dark Energy in a Non-flat Universe

abstract:
  We study the model for holographic dark energy in a spatially closed
universe, generalizing the proposal in hep-th/0403127 for a flat universe. We
provide independent arguments for the choice of the parameter $c=1$ in the
holographic dark energy model. On the one hand, $c$ can not be less than 1, to
avoid violating the second law of thermodynamics. On the other hand,
observation suggests $c$ be very close to 1, it is hard to justify a small
deviation of $c$ from 1, if $c>1$.


title: Neutron Captures in the r-Process

abstract:
  The r-process involves neutron-rich nuclei far off stability for which no
experimental cross sections are known. Therefore, one has to rely on theory.
The difficulties in the predictions are briefly addressed. To investigate the
impact of altered rates, a comparison of r-process production in hot bubble
models with largely varied rates is shown. Due to the (n,gamma)-(gamma,n)
equilibrium established at the onset of the r-process, only late-time neutron
captures are important which mainly modify the abundances around the third
r-process peak.


title:
Quantitative studies of the Far-UV, UV and optical spectra of late O and
  early B-type supergiants in the Magellanic Clouds

abstract:
  We present quantitative studies of 8 late O and early B-type supergiants in
the Magellanic Clouds using far-ultraviolet FUSE, ultraviolet IUE/HST and
optical VLT-UVES spectroscopy. Temperatures, mass-loss rates and CNO abundances
are obtained using the non-LTE, spherical, line-blanketed model atmosphere code
of Hillier & Miller (1998). We support recent results for lower temperatures of
OB-type supergiants as a result of stellar winds and blanketing, which amounts
to ~2000 K at B0 Ia. In general, H$\alpha$ derived mass-loss rates are
consistent with UV and far-UV spectroscopy, although from consideration of the
SIV $\lambda\lambda$1063-1073 doublet, clumped winds are preferred over
homogenous models. AV 235 (B0 Iaw) is a notable exception, which has an
unusually strong H$\alpha$ profile that is inconsistent with the other Balmer
lines and UV wind diagnostics. We also derive CNO abundances for our sample,
revealing substantial nitrogen enrichment, with carbon and oxygen depletion.
Our results are supported by comparison with the Galactic supergiant HD 2905
(BC0.7 Ia) for which near-solar CNO abundances are obtained. This bolsters
previous suggestions that ``normal'' OB-type supergiants exhibit atmospheric
compositions indicative of partical CNO processing.


title:
Lightcurve Classification in Massive Variability Surveys II: Transients
  towards the Large Magellanic Cloud

abstract:
  Automatic classification of variability is now possible with tools like
neural networks. Here, we present two neural networks for the identification of
microlensing events -- the first discriminates against variable stars and the
second against supernovae. The inputs to the networks include parameters
describing the shape and the size of the lightcurve, together with colour of
the event. The network computes the posterior probability of microlensing,
together with an estimate of the likely error. An algorithm is devised for
direct calculation of the microlensing rate from the output of the neural
networks. We present a new analysis of the microlensing candidates towards the
Large Magellanic Cloud (LMC). The neural networks confirm the microlensing
nature of only 7 of the possible 17 events identified by the MACHO experiment.
This suggests that earlier estimates of the microlensing optical depth towards
the LMC may have been overestimated. A smaller number of events is consistent
with the assumption that all the microlensing events are caused by the known
stellar populations in the outer Galaxy/LMC.


title: The Classification of Universes

abstract:
  We define a universe as the contents of a spacetime box with comoving walls,
large enough to contain essentially all phenomena that can be conceivably
measured. The initial time is taken as the epoch when the lowest CMB modes
undergo horizon crossing, and the final time taken when the wavelengths of CMB
photons are comparable with the Hubble scale, i.e. with the nominal size of the
universe. This allows the definition of a local ensemble of similarly
constructed universes, using only modest extrapolations of the observed
behavior of the cosmos. We then assume that further out in spacetime, similar
universes can be constructed but containing different standard model
parameters. Within this multiverse ensemble, it is assumed that the standard
model parameters are strongly correlated with size, i.e. with the value of the
inverse Hubble parameter at the final time, in a manner as previously
suggested. This allows an estimate of the range of sizes which allow life as we
know it, and invites a speculation regarding the most natural distribution of
sizes. If small sizes are favored, this in turn allows some understanding of
the hierarchy problems of particle physics. Subsequent sections of the paper
explore other possible implications. In all cases, the approach is as bottoms
up and as phenomenological as possible, and suggests that theories of the
multiverse so constructed may in fact lay some claim of being scientific.


title: Ultracompact Binaries as Bright X-Ray Sources in Elliptical Galaxies

abstract:
  Chandra observations of distant elliptical galaxies have revealed large
numbers of Low Mass X-ray Binaries (LMXBs) accreting at rates in excess of
10^{-8} solar masses per year. The majority of these LMXBs reside in globular
clusters (GCs) and it has been suggested that many of the field LMXBs also
originated in GCs. We show here that ultracompact binaries with orbital periods
of 8-10 minutes and He or C/O donors of 0.06-0.08 solar masses naturally
provide the observed accretion rates from gravitational radiation losses alone.
Such systems are predicted to be formed in the dense GC environment, a
hypothesis supported by the 11.4 minute binary 4U 1820-30, the brightest
persistent LMXB in a Galactic GC. These binaries have short enough lifetimes
(less then 3 Myr) while bright that we calculate their luminosity function
under a steady-state approximation. This yields a luminosity function slope in
agreement with that observed for luminosities in the range of 6E37 ergs/sec to
5E38 ergs/sec, encouraging us to use the observed numbers of LMXBs per GC mass
to calculate the accumulated number of ultracompact binaries. For a constant
birthrate over 8 Gyrs, the number of ultracompact binaries which have evolved
through this bright phase is nearly 4000 in a 10 million solar mass GC,
consistent with dynamical interaction calculations. Perhaps most importantly,
if all ultracompacts become millisecond radio pulsars, then the observed
normalization agrees with the inferred number of millisecond radio pulsars in
47 Tuc and Galactic GCs in general.


title:
The Kinematics of Morphologically Selected z~2 Galaxies in the GOODS-N
  Field

abstract:
  We present near-IR spectra of H-alpha emission from 13 galaxies at z~2 in the
GOODS-N field. The galaxies were selected primarily because they appear to have
elongated morphologies, and slits were aligned with the major axes (as
determined from the rest-frame UV emission) of 11 of the 13. If the galaxies
are elongated because they are highly inclined, alignment of the slit and major
axis should maximize the observed velocity and reveal velocity shear, if
present. In spite of this alignment, we see spatially resolved velocity shear
in only two galaxies. We show that the seeing makes a large difference in the
observed velocity spread of a tilted emission line, and use this information to
place limits on the velocity spread of the ionized gas of the galaxies in the
sample: we find that all 13 have v_{0.5} < 110 km/s, where v_{0.5} is the
velocity shear (half of the velocity range of a tilted emission line) that
would be observed under our best seeing conditions of ~0.5". When combined with
previous work, our data also indicate that aligning the slit along the major
axis does not increase the probability of observing a tilted emission line. We
then focus on the one-dimensional velocity dispersion \sigma, which is much
less affected by the seeing, and see that the elongated subsample exhibits a
significantly lower velocity dispersion than galaxies selected at random from
our total H-alpha sample, not higher as one might have expected. We also see
some evidence that the elongated galaxies are less reddened than those randomly
selected using only UV colors. Both of these results are counter to what would
be expected if the elongated galaxies were highly inclined disks. It is at
least as likely that the galaxies' elongated morphologies are due to merging
subunits.


title:
The ESO-Sculptor Survey: Evolution of late-type galaxies at redshifts
  0.1-0.5

abstract:
  [ABRIDGED] Using the Gaussian+Schechter composite luminosity functions
measured from the ESO-Sculptor Survey (de Lapparent et al. 2003), we obtain
evidence for evolution in the late spectral class containing late-type Spiral
(Sc+Sd) and dwarf Irregular (dI) galaxies. This evolution is detected as an
increase of the Sc+Sd+dI galaxy density which can be modeled as either
n(z)~1+3(z-0.15) or n(z) ~ (1+z)^2 using the currently favored cosmological
parameters Omega_m=0.3 and Omega_Lambda=0.7, with an uncertainty in both
evolution rates of order of unity. For Omega_m=1.0 and Omega_Lambda=0.0, the
linear and power-law evolution rates are 4 and 2.5 resp. Both models yield a
good match to the ESS BVRc redshift distributions to 21-22 mag and to the
number-counts to 23-23.5 mag, which probe the galaxy distribution to redshifts
z~0.5 and z~1.0 resp. This analysis illustrates how Gaussian+Schechter
composite luminosity functions provide more robust constraints on the evolution
rate than pure Schechter functions. The detected density evolution indicates
that mergers could play a significant role in the evolution of late-type Spiral
and dwarf Irregular galaxies. However, the ESO-Sculptor density increase with
redshift could also be caused by a ~1 mag brightening of the Sc+Sd+dI galaxies
at z~0.5 and a ~1.5-2.0 mag brightening at z~1, which is compatible with the
expected passive brightening of Sc galaxies at these redshifts. Distinguishing
between luminosity and density evolution is a major difficulty as these produce
the same effect on the redshift and magnitude distributions. The detected
evolution rate of the ESO-Sculptor Sc+Sd+dI galaxies is nevertheless among the
range of measured values from the other existing analyses, whether they provide
evidence for density or luminosity evolution.


title:
Fast Cosmological Parameter Estimation from Microwave Background
  Temperature and Polarization Power Spectra

abstract:
  We improve the algorithm of Kosowsky, Milosavljevic, and Jimenez (2002) for
computing power spectra of the cosmic microwave background. The present
algorithm computes not only the temperature power spectrum but also the E-mode
polarization and the temperature-polarization cross power spectra, providing
the accuracy required for current cosmological parameter estimation. We refine
the optimum set of cosmological parameters for computing the power spectra as
perturbations around a fiducial model, leading to an accuracy better than 0.5%
for the temperature power spectrum throughout the region of parameter space
within WMAP's first-year 3sigma confidence region. This accuracy is comparable
to the difference between the widely-used CMBFAST code (Seljak and Zaldarriaga
1996) and Boltzmann codes. Our algorithm (CMBwarp) makes possible a full
exploration of the likelihood region for eight cosmological parameters in about
one hour on a laptop computer. We provide the code to compute power spectra as
well as the Markov Chain Monte Carlo algorithm for cosmological parameters
estimation at http://www.physics.upenn.edu/~raulj/CMBwarp


title:
Observational Signature of Tidal Disruption of a Star by a Massive Black
  Hole

abstract:
  We have modeled the time-variable profiles of the Halpha emission line from
the non-axisymmetric disk and debris tail created in the tidal disruption of a
solar-type star by a million solar mass black hole. We find that the line
profiles at these very early stages of the evolution of the post-disruption
debris do not resemble the double peaked profiles expected from a rotating disk
since the debris has not yet settled into such a stable structure. The
predicted line profiles vary on fairly short time scales (of order hours to
days). As a result of the uneven distribution of the debris and the existence
of a ``tidal tail'' (the stream of returning debris), the line profiles depend
sensitively on the orientation of the tail relative to the line of sight. Given
the illuminating UV/X-ray light curve, we also model the Halpha light curve
from the debris.


title: The Mass Assembly History of Galaxies and Clusters of Galaxies

abstract:
  We discuss the mass assembly history both on cluster and galaxy scales and
their impact on galaxy evolution. On cluster scale, we introduce our on-going
PISCES project on Subaru, which plans to target ~15 clusters at 0.4<z<1.3 using
the unique wide-field (30') optical camera Suprime-Cam and the spectrograph
both in optical (FOCAS, 6') and near-infrared (FMOS, 30'). The main objectives
of this project are twofold: (1) Mapping out the large scale structures in and
around the clusters on 10-14 Mpc scale to study the hierarchical growth of
clusters through assembly of surrounding groups. (2) Investigating the
environmental variation of galaxy properties along the structures to study the
origin of the morphology-density and star formation-density relations. Some
initial results are presented. On galactic scale, we first present the stellar
mass growth of cluster galaxies out to z~1.5 based on the near-infrared imaging
of distant clusters and show that the mass assembly process of galaxies is
largely completed by z~1.5 and is faster than the current semi-analytic models'
predictions. We then focus on the faint end of the luminosity function at z~1
based on the Subaru/XMM-Newton Deep Survey imaging data. We show the deficit of
red galaxies below M*+2 or 10^{10} Msun, which suggest less massive galaxies
are either genuinely young or still vigorously forming stars in sharp contrast
to the massive galaxies where mass is assembled and star formation is
terminated long time ago.


title: Final Stages of Planet Formation

abstract:
  We address three questions regarding solar system planets. What determined
their number? Why are their orbits nearly circular and coplanar? How long did
they take to form? Runaway accretion in a disk of small bodies resulted in a
tiny fraction of the bodies growing much larger than all the others. This was
followed by oligarchic growth during which the big bodies maintained similar
masses and uniformly spaced semi-major axes. We depart from standard treatments
of planet formation by assuming that as the big bodies got bigger, the small
ones got smaller as the result of undergoing a collisional fragmentation
cascade. It follows that oligarchy was a brief stage in solar system evolution.
When the oligarchs' surface mass density matched that of the small bodies,
dynamical friction was no longer able to balance viscous stirring, so their
velocity dispersion increased to the extent that their orbits crossed. This
marked the end of oligarchy. What happened next differed in the inner and outer
parts of the planetary system. In the inner part, where the ratios of the
escape velocities from the surfaces of the planets to the escape velocities
from their orbits are smaller than unity, big bodies collided and coalesced
after their random velocities became comparable to their escape velocities. In
the outer part, where these ratios are larger than unity, the random velocities
of some of the big bodies continued to rise until they were ejected. In both
parts, the number density of the big bodies eventually decreased to the extent
that gravitational interactions among them no longer produced large scale
chaos. After that their orbital eccentricities and inclinations were damped by
dynamical friction from the remaining small bodies. The last and longest stage
in planet formation was the clean up of small bodies.


title: In Search of the Dark Ages -- An Experimental Challenge

abstract:
  Most direct source detections beyond z~7 are likely to arise from wide-field
narrowband surveys of Ly-a emission in the J band. For this to be true, the
Ly-a emission must somehow escape from compact star-forming regions (CSR)
presumably associated with massive haloes. Since the Ly-a escape fraction is
<10% from an emitting region of size roughly 1 kpc, these objects will be
difficult to find and hard to detect. For CSR sources, existing large-format IR
arrays are close to ideal in terms of their noise characteristics for
conducting "wide-field" narrowband surveys where pixel sizes are 0.1" or
larger. However, we stress that Ly-a can also arise from external large-scale
shocks (ELS) due to starburst winds, powered by CSRs, ploughing into gas
actively accreting onto the dark halo. The winds effectively carry energy from
the dense, dusty environment of a starburst into lower density regions, where
the escape probability for Ly-a photons is greater. ELS emission is expected to
be considerably more clumpy (<100 pc; ~0.01") than CSR emission. For a
"targetted" observation of an ELS source, IR arrays will need two orders of
magnitude improvement in dark current if we wish to detect dispersed clumpy
emission within the environment of a massive halo. For either targetted or
wide-field surveys, the deepest observations will be those where the pixel
sampling is well matched to the size of the emitting regions. We show that
there are only 3 -- 4 J-band windows [z = 7.72, (8.22), 8.79, 9.37] suitable
for observing the Dark Ages in Ly-a; we summarize their cosmological properties
in Table 1.


title:
Quasi-Periodicity in global solar radio flux at metric wavelengths
  during Noise Storms

abstract:
  We present observational results from studying the quasi-periodicities in
global solar radio flux during periods of enhanced noise storm activity, over
durations of ~4 hrs a day ("intra-day" variations), observed at 77.5 MHz with
the newly commissioned log-periodic array tracking system at the Gauribidanur
radio observatory. Positional information on the storm centers were obtained
with the radio imaging data from the Nancay (sic.) Radioheliograph (NRH), while
their active region (AR) counterparts on the photosphere (and the overlying
chromosphere) were located from the H-alpha images of the Big Bear Solar
Observatory (BBSO). The quasi-periodicity in flux was found to be 110 minutes,
with the fluctuation in flux being 3(+/- 1.5) solar flux units (sfu). The
results of such pulsations are interpreted qualitatively as evidence for
coronal seismology.


title:
Probing the inner wind of AGB stars: Interferometric observations of SiO
  millimetre line emission from the oxygen-rich stars R Dor and L2 Pup

abstract:
  High angular resolution Australia Telescope Compact Array (ATCA) observations
of SiO `thermal' millimetre line emission towards the two oxygen-rich, low mass
loss rate AGB stars R Dor and L2 Pup are presented. In both cases the emission
is resolved with an overall spherical symmetry. Detailed radiative transfer
modelling of the SiO line emission has been performed, and the comparison
between observations and models are conducted in the visibility plane,
maximizing the sensitivity. The excitation analysis suggests that the abundance
of SiO is as high as 4E-5 in the inner part of the wind, close to the predicted
values from stellar atmosphere models. Beyond a radius of ~ 1E15 cm the SiO
abundance is significantly lower, about 3E-6, until it decreases strongly at a
radius of about 3E15 cm. This is consistent with a scenario where SiO first
freezes out onto dust grains, and then eventually becomes photodissociated by
the interstellar UV-radiation field. In these low expansion velocity sources
the turbulent broadening of the lines plays an important role in the line
formation. Micro-turbulent velocity widths in the range 1.1-1.5 km/s result in
a very good reproduction of the observed line shapes even if the gas expansion
velocity is kept constant. This, combined with the fact that the SiO and CO
lines are well fitted using the same gas expansion velocity (to within 5-10%),
suggest that the envelope acceleration occurs close to the stellar photosphere,
within 20-30 stellar radii.


title:
Velocity centroids and the structure of interstellar turbulence: I.
  Analytical study

abstract:
  We present an analytical study of the statistical properties of integrated
emission and velocity centroids for a slightly compressible turbulent slab
model, to retrieve the underlying statistics of three-dimensional density and
velocity fluctuations. Under the assumptions that the density and velocity
fields are homogeneous and isotropic, we derive the expressions of the antenna
temperature for an optically thin spectral line observation, and of its
successive moments with respect to the line of sight velocity component,
focusing on the zeroth (intensity or integrated emission I) and first
(non-normalized velocity centroid C) moments. The ratio of the latter to the
former is the normalized centroid C_0, whose expression can be linearized for
small density fluctuations. To describe the statistics of I, C and C_0, we
derive expansions of their autocorrelation functions in powers of density
fluctuations and perform a lowest-order real-space calculation of their scaling
behaviour, assuming that the density and velocity fields are fractional
Brownian motions. We hence confirm, within the scope of this study, the
property recently found numerically by Miville-Deschenes, Levrier and Falgarone
(2003, ApJ, 593, 831) that the spectral index of the normalized centroid is
equal to that of the full velocity field. However, it is also argued that, in
order to retrieve the velocity statistics, normalization of centroids may
actually not be the best way to remove the influence of density fluctuations.
In this respect, we discuss the modified velocity centroids introduced by
Lazarian and Esquivel (2003, ApJL, 592, 37) as a possible alternative. In a
following paper, we shall present numerical studies aimed at assessing the
validity domain of these results.


title: Physical regimes for feedback in galaxy formation

abstract:
  We present a new (semi-)analytic model for feedback in galaxy formation. The
ISM is modeled as a two-phase medium in pressure equilibrium. The remnants of
exploding type II SNe percolate into super-bubbles (SBs) that sweep the ISM,
heating the hot phase (if the SB is adiabatic) or cooling it (in the snowplow
stage, when the interior gas of the SB has cooled). The resulting feedback
regimes occur in well-defined regions of the space defined by vertical
scale-length and surface density of the structure. When SBs blow out in the
adiabatic regime, the efficiency of SNe in heating the ISM is ~5 per cent, with
\~80 per cent of the energy budget injected into the external halo, and the
outcoming ISM is self-regulated to a state similar to that found in the Milky
Way. Feedback is most efficient when SBs are pressure-confined in the adiabatic
regime. In some significant regions of the parameter space confinement takes
place in the snowplow stage; then the hot phase has a lower temperature and
star formation is quicker. In some critical cases, the hot phase is strongly
depleted and the cold phase percolates the whole volume, giving rise to a
sudden burst of star formation. Strong galactic winds are predicted to happen
only in critical cases. This model provides a starting point for constructing a
realistic grid of feedback solutions to be used in galaxy formation codes. The
predictive power of this model extends to many properties of the ISM, so that
most parameters can be constrained by reproducing the main properties of the
Milky Way. (Abridged)


title: Resetting chemical clocks of hot cores based on S-bearing molecules

abstract:
  We report a theoretical study of sulphur chemistry, as applied to hot cores,
where S-bearing molecular ratios have been previously proposed and used as
chemical clocks. As in previous models, we follow the S-bearing molecular
composition after the injection of grain mantle components into the gas phase.
For this study, we developed a time-dependent chemical model with up-to-date
reaction rate coefficients. We ran several cases, using different realistic
chemical compositions for the grain mantles and for the gas prior to mantle
evaporation. The modeling shows that S-bearing molecular ratios depend very
critically on the gas temperature and density, the abundance of atomic oxygen,
and, most importantly, on the form of sulphur injected in the gas phase, which
is very poorly known. Consequently, ratios of S-bearing molecules cannot be
easily used as chemical clocks. However, detailed observations and careful
modeling of both physical and chemical structure can give hints on the source
age and constrain the mantle composition (i.e. the form of sulphur in cold
molecular clouds) and, thus, help to solve the mystery of the sulphur
depletion. We analyse in detail the cases of Orion and IRAS16293-2422. The
comparison of the available observations with our model suggests that the
majority of sulphur released from the mantles is mainly in, or soon converted
into, atomic form.


title:
Photometry of Magellanic Cloud clusters with the Advanced Camera for
  Surveys - I. The old LMC clusters NGC 1928, 1939 and Reticulum

abstract:
  (Abridged) We present the results of photometric measurements from images of
the LMC globular clusters NGC 1928, 1939 and Reticulum taken with ACS on HST.
F555W and F814W exposures result in high accuracy CMDs for these three
clusters. This is the first time that CMDs for NGC 1928 and 1939 have been
published. All three clusters possess CMDs with features indicating them to be
>10 Gyr old, including main sequence turn-offs at V~23 and well populated HBs.
We use the CMDs to obtain metallicity and reddening estimates for each cluster.
NGC 1939 is a metal poor cluster, with [Fe/H] = -2.10 +/- 0.19, while NGC 1928
is significantly more metal rich, with [Fe/H] = -1.27 +/- 0.14. Reticulum's
abundance lies between the two, at [Fe/H] = -1.66 +/- 0.12. All three clusters
are moderately reddened with values ranging from E(V-I) = 0.07 +/- 0.02 for
Reticulum and E(V-I) = 0.08 +/- 0.02 for NGC 1928, to E(V-I) = 0.16 +/- 0.03
for NGC 1939. We estimate the HB morphology of each cluster. NGC 1928 and 1939
possess HBs consisting almost exclusively of stars to the blue of the
instability strip. In contrast, Reticulum has an intermediate HB morphology,
with stars across the instability strip. Using a variety of dating techniques
we show that these three clusters are coeval with each other and the oldest
Galactic and LMC globular clusters, to within ~2 Gyr. The census of known old
LMC globular clusters therefore now numbers 15 plus the unique, somewhat
younger cluster ESO121-SC03. The NGC 1939 field contains another cluster in the
line-of-sight, NGC 1938. A CMD for this object shows it to be less than ~400
Myr old, and it is therefore unlikely to be physically associated with NGC
1939.


title:
Interferometric observations of the Mira star o Ceti with the VLTI/VINCI
  instrument in the near-infrared

abstract:
  We present K-band commissioning observations of the Mira star prototype o Cet
obtained at the ESO Very Large Telescope Interferometer (VLTI) with the VINCI
instrument and two siderostats. The observations were carried out between 2001
October and December, in 2002 January and December, and in 2003 January.
Rosseland angular radii are derived from the measured visibilities by fitting
theoretical visibility functions obtained from center-to-limb intensity
variations (CLVs) of Mira star models (Bessel et al. 1996, Hofmann et al. 1998,
Tej et al. 2003). Using the derived Rosseland angular radii and the SEDs
reconstructed from available photometric and spectrophotometric data, we find
effective temperatures ranging from T_eff=3192 +/- 200 K at phase phi=0.13 to
2918 +/- 183 K at phi=0.26. Comparison of these Rosseland radii, effective
temperatures, and the shape of the observed visibility functions with model
predictions suggests that o Cet is a fundamental mode pulsator. Furthermore, we
investigated the variation of visibility function and diameter with phase. The
Rosseland angular diameter of o Cet increased from 28.9 +/- 0.3 mas
(corresponding to a Rosseland radius of 332 +/- 38 R_sun for a distance of
D=107 +/- 12 pc) at phi=0.13 to 34.9 +/- 0.4 mas (402 +/- 46 R_sun) at phi=0.4.
The error of the Rosseland linear radius almost entirely results from the error
of the parallax, since the error of the angular diameter is only approximately
1 %.


title:
The infrared properties of the new outburst star IRAS 05436-0007 in
  quiescent phase

abstract:
  We compiled and investigated the infrared/sub-mm/mm SED of the new outburst
star IRAS 05436-0007 in quiescent phase. The star is a flat-spectrum source,
with an estimated total luminosity of L_bol ~ 5.6 L_sun, typical of low-mass T
Tauri stars. The derived circumstellar mass of 0.5 M_sun is rather high among
low-mass YSOs. The observed SED differs from the SEDs of typical T Tauri stars
and of 4 well-known EXors, and resembles more the SEDs of FU Orionis objects
indicating the presence of a circumstellar envelope. IRAS 05436-0007 seems to
be a Class II source with an age of approximately 4x10^5 yr. In this
evolutionary stage an accretion disk is already fully developed, though a
circumstellar envelope may also be present. Observations of the present
outburst will provide additional knowledge on the source.


title:
Candidates for giant lobes projecting from the LBV stars P Cygni and R
  143

abstract:
  Deep, wide-field, continuum-subtracted, images in the light of the
Halpha+[NII] 6548 & 6584 A and [O III] 5007 A nebular emission lines have been
obtained of the environment of the Luminous Blue Variable (LBV) star P Cygni. A
previously discovered, receding, nebulous filament along PA 50 deg has now been
shown to extend up to 12' from this star. Furthermore, in the light of [O III]
5007 A, a southern counterpart is discovered as well as irregular filaments on
the opposite side of P Cygni.
  Line profiles from this nebulous complex indicate that this extended
nebulosity is similar to that associated with middle-aged supernova remnants.
However, there are several indications that it has originated in P Cygni and is
not just a chance superposition along the same sight-line. This possibility is
explored here and comparison is made with a new image of the LBV star R 143 in
the LMC from which similar filaments appear to project.
  The dynamical age of the P Cygni giant lobe of ~5x10^{4} yr is consistent
with both the predicted and observed durations of the LBV phases of 50M stars
after they have left the main sequence. Its irregular shape may have been
determined by the cavity formed in the ambient gas by the energetic wind of the
star, and shaped by a dense torus, when on the main sequence.
  The proper motion and radial velocity of P Cygni, with respect to its local
environment, could explain the observed angular and kinematical shifts of the
star compared with the giant lobe.


title: On the lifetime of metastable states in self-gravitating systems

abstract:
  We discuss the physical basis of the statistical mechanics of
self-gravitating systems. We show the correspondance between statistical
mechanics methods based on the evaluation of the density of states and
partition function and thermodynamical methods based on the maximization of a
thermodynamical potential (entropy or free energy). We address the question of
the thermodynamic limit of self-gravitating systems, the justification of the
mean-field approximation, the validity of the saddle point approximation near
the transition point, the lifetime of metastable states and the fluctuations in
isothermal spheres. In particular, we emphasize the tremendously long lifetime
of metastable states of self-gravitating systems which increases exponentially
with the number of particles N except in the vicinity of the critical point.
More specifically, using an adaptation of the Kramers formula justified by a
kinetic theory, we show that the lifetime of a metastable state scales as e^{N
Delta s} in microcanonical ensemble and e^{N Delta j} in canonical ensemble,
where Delta s and Delta j are the barriers of entropy and free energy j=s-beta
epsilon (per particle) respectively. The physical caloric curve must take these
metastable states (local entropy maxima) into account. As a result, it becomes
multi-valued and leads to microcanonical phase transitions and ``dinosaur's
necks''(Chavanis 2002b, Chavanis & Rieutord 2003). The consideration of
metastable states answers the critics raised by D.H.E. Gross [cond-mat/0307535;
cond-mat/0403582].


title:
Astrometric proof of companionship for the L dwarf companion candidate
  GJ 1048B

abstract:
  Gizis et al. (2001) reported a companion candidate of spectral type L1 near
the K2 dwarf GJ 1048 using the Two Micron All-Sky Survey (2MASS). At that time
it was not possible to verify companionship astrometrically using the 2MASS
data alone due to the small proper motion of GJ 1048. We now show that both
objects share the same proper motion by using data from the UK Schmidt
Telescope Near-infrared (IVN) Southern Survey as the first epoch and data from
2MASS as the second epoch. Our technique of subtracting the PSF of the primary
from the SuperCOSMOS I scans of the Southern Survey enables the astrometry of
the companion candidate to be measured directly.


title:
Angular Power Spectrum Estimation of Cosmic Ray Anisotropies with Full
  or Partial Sky Coverage

abstract:
  We study the angular power spectrum estimate in order to search for large
scale anisotropies in the arrival directions distribution of the highest-energy
cosmic rays. We show that this estimate can be performed even in the case of
partial sky coverage and validated over the full sky under the assumption that
the observed fluctuations are statistically spatial stationary. If this
hypothesis - which can be tested directly on the data - is not satisfied, it
would prove, of course, that the cosmic ray sky is non isotropic but also that
the power spectrum is not an appropriate tool to represent its anisotropies,
whatever the sky coverage available. We apply the method to simulations of the
Pierre Auger Observatory, reconstructing an input power spectrum with the
Southern site only and with both Northern and Southern ones. Finally, we show
the improvement that a full-sky observatory brings to test an isotropic
distribution, and we discuss the sensitivity of the Pierre Auger Observatory to
large scale anisotropies.


title: Conservative Formulations of General Relativistic Radiative Transfer

abstract:
  Accurate accounting of particle number and 4-momentum in radiative transfer
may be facilitated by the use of transport equations that allow transparent
conversion between volume and surface integrals in both spacetime and momentum
space. Such conservative formulations of general relativistic radiative
transfer in multiple spatial dimensions are presented, and their relevance to
core-collapse supernova simulations described.


title: The evolution of substructure II: linking dynamics to environment

abstract:
  We present results from a series of high-resolution N-body simulations that
focus on the formation and evolution of eight dark matter halos, each of order
a million particles within the virial radius. We follow the time evolution of
hundreds of satellite galaxies with unprecedented time resolution, relating
their physical properties to the differing halo environmental conditions. The
self-consistent cosmological framework in which our analysis was undertaken
allows us to explore satellite disruption within live host potentials, a
natural complement to earlier work conducted within static potentials. Our host
halos were chosen to sample a variety of formation histories, ages, and
triaxialities; despite their obvious differences, we find striking similarities
within the associated substructure populations. Namely, all satellite orbits
follow nearly the same eccentricity distribution with a correlation between
eccentricity and pericentre. We also find that the destruction rate of the
substructure population is nearly independent of the mass, age, and triaxiality
of the host halo. There are, however, subtle differences in the velocity
anisotropy of the satellite distribution. We find that the local velocity bias
at all radii is greater than unity for all halos and this increases as we move
closer to the halo centre, where it varies from 1.1 to 1.4. For the global
velocity bias we find a small but slightly positive bias, although when we
restrict the global velocity bias calculation to satellites that have had at
least one orbit, the bias is essentially removed.


title: Tidal Disruption of a Star By a Black Hole : Observational Signature

abstract:
  We have modeled the time-variable profiles of the Halpha emission line from
the non-axisymmetric disk and debris tail created in the tidal disruption of a
solar-type star by a million solar mass black hole. Two tidal disruption event
simulations were carried out using a three dimensional relativistic
smooth-particle hydrodynamic code, to describe the early evolution of the
debris during the first fifty to ninety days. We have calculated the physical
conditions and radiative processes in the debris using the photoionization code
CLOUDY. We model the emission line profiles in the period immediately after the
accretion rate onto the black hole became significant. We find that the line
profiles at these very early stages of the evolution of the post-disruption
debris do not resemble the double peaked profiles expected from a rotating disk
since the debris has not yet settled into such a stable structure. As a result
of the uneven distribution of the debris and the existence of a ``tidal tail''
(the stream of returning debris), the line profiles depend sensitively on the
orientation of the tail relative to the line of sight. Moreover, the predicted
line profiles vary on fairly short time scales (of order hours to days). Given
the accretion rate onto the black hole we also model the Halpha light curve
from the debris and the evolution of the Halpha line profiles in time.


title:
The Fine-structure Constant as a Probe of Chemical Evolution and AGB
  Nucleosynthesis in Damped Lyman-alpha Systems

abstract:
  Evidence from a large sample of quasar absorption-line spectra in damped
Lyman-alpha systems has suggested a possible time variation of the fine
structure constant alpha. The most statistically significant portion of this
sample involves the comparison of Mg and Fe wavelength shifts using the
many-multiplet (MM) method. However, the sensitivity of this method to the
abundance of heavy isotopes, especially Mg, is enough to imitate an apparent
variation in alpha in the redshift range 0.5 < z < 1.8. We implement recent
yields of intermediate mass (IM) stars into a chemical evolution model and show
that the ensuing isotope distribution of Mg can account for the observed
variation in alpha provided the early IMF was particularly rich in intermediate
mass stars (or the heavy Mg isotope yields from AGB stars are even higher than
in present-day models). As such, these observations of quasar absorption
spectra can be used to probe the nucleosynthetic history of low-metallicity
damped Lyman-alpha systems in the redshift range 0.5 < z < 1.8. This analysis,
in conjunction with other abundance measurements of low-metallicity systems,
reinforces the mounting evidence that star formation at low metallicities may
have been strongly influenced by a population of IM stars. Such IM stars have a
significant influence on other abundances, particularly nitrogen. We constrain
our models with independent measurements of N, Si, and Fe in damped Lyman-alpha
systems as well as C/O in low-metallicity stars. In this way, we obtain
consistent model parameters for this chemical-evolution interpretation of the
MM method results.


title: The evolution substructure I: a new identification method

abstract:
  We describe our new "MLAPM-halo-finder" (MHF) which is based on the adaptive
grid structure of the N-body code MLAPM. We then extend the MHF code in order
to track the orbital evolution of gravitationally bound objects through any
given cosmological N-body simulation - our so-called "MLAPM-halo-tracker"
(MHT). The mode of operation of MHT is demonstrated using a series of eight
high-resolution N-body simulations of galaxy clusters. Each of these halos
hosts more than one million particles within their virial radii Rvir. We use
MHT as well as MHF to follow the temporal evolution of hundreds of individual
satellites, and show that the radial distribution of these substructure
satellites follows a "universal" radial distribution irrespective of the host
halo's environment and formation history. This in fact might pose another
problem for simulations of CDM structure formation as there are recent findings
by Taylor et al. (2003) that the Milky Way satellites are found preferentially
closer to the galactic centre and simulations underestimate the amount of
central substructure, respectively. Further, this universal substructure
profile is anti-biased with respect to the underlying dark matter profile. Both
the halo finder MHF and the halo tracker MHT will become part of the open
source MLAPM distribution.


title:
Collisionless evaporation from cluster elliptical galaxies: a
  contributor to the intracluster stellar population

abstract:
  By means of simple numerical models we discuss whether "collisionless stellar
evaporation" from cluster elliptical galaxies could be an effective mechanism
for the production of intracluster stellar populations. The effectiveness of
this mechanism is due to the fact that, for realistic galaxy and cluster
models, the galaxy oscillation periods near equilibrium configurations in the
cluster tidal field are of the same order of stellar orbital times in the
external parts of the galaxies themselves. With the aid of Monte-Carlo
simulations we explore the evolution of stellar orbits in oscillating galaxies
placed near different equilibrium positions. We found that, over an Hubble
time, the main effect is a substantial expansion of the galactic outskirts,
particularly affecting the galaxy at the cluster center and those orbiting near
the cluster core radius: overall, approximately the 10% of the galaxy mass is
affected. Thus, the proposed mechanism could be of some importance in the
shaping of the halo of cD galaxies and in making easier ``galaxy harassment''
in the formation of the intracluster stellar population.


title: X-Ray and Infrared Observations of Embedded Young Stars in L1630

abstract:
  The HH 24-26 star-forming region within the L1630 dark cloud in Orion
contains a remarkable collection of rare Class 0 and Class I protostars,
collimated molecular and ionized jets, and a luminous but spatially unresolved
ASCA X-ray source. To study the X-ray properties of the embedded protostar
population of that region, we have obtained a deep X-ray image with the ACIS-S
camera on board the Chandra X-Ray Observatory. A number of H-alpha
emission-line objects were detected in the areas surrounding HH 24-26, of which
the weak-line T Tauri star SSV 61 was the brightest source, at a steady
luminosity of 10^31.9 erg/s (0.3-10 keV). Two Class I protostars aligned with
optical jets in HH 24, SSV 63E and SSV 63W, were also detected, as was the
continuum radio source SSV 63NE, which is very likely an extreme Class I or
Class 0 object. We observed no X rays from the Class 0 protostars HH 24-MMS and
HH 25-MMS, nor any from regions of the cloud bounded by HH 25 and HH 26, at a
2-sigma upper limit of 10^30.0 erg/s. HH 26-IR, the Class I object thought to
be the origin of the HH 26 flow, was not detected. Near-infrared spectroscopy
obtained at the NASA IRTF reveals 3 micron ice bands in the spectra of SSV 59,
63E, 63W, and HH 26-IR, and 2.3 micron CO overtone absorption bands for SSV 61.
SSV 60, which lies astride one end of the great arc of nebulosity forming HH
25, exhibits a deep infrared ice band and CO absorption, but is not an X-ray
source, and is most likely a distant background giant of late spectral type.


title:
Eclipse mapping of the flickering sources in the dwarf nova V2051
  Ophiuchi

abstract:
  We report on the eclipse mapping analysis of an ensemble of light curves of
the dwarf nova V2051 Oph with the aim to study the spatial distribution of its
steady-light and flickering sources. The data are combined to derive the
orbital dependency of the steady-light and the flickering components at two
different brightness levels, named the 'faint' and 'bright' states. The
differences in brightness are caused by long-term variations in the mass
transfer rate from the secondary star. Eclipse maps of the steady-light show
enhanced emission along the ballistic stream trajectory, in a clear evidence of
gas stream overflow. We identify two different and independent sources of
flickering in V2051 Oph. Low-frequency flickering arises in the overflowing gas
stream and is associated to the mass transfer process. It maximum emission
occurs at the position of closest approach of the gas stream to the white
dwarf, and its spatial distribution changes in response to variations in mass
transfer rate. High-frequency flickering originates in the accretion disk,
showing a radial distribution similar to that of the steady-light maps and no
evidence of emission from the hot spot, gas stream or white dwarf. This disk
flickering component has a relative amplitude of about 3 per cent of the steady
disk light, independent of disk radius and brightness state. If the disk
flickering is caused by fluctuations in the energy dissipation rate induced by
MHD turbulence, its relative amplitude lead to a viscosity parameter alpha=
0.1-0.2 at all radii for the quiescent disk. This value seems uncomfortably
high to be accommodated by the disk instability model [abridged].


title: Dust-to-gas ratios in the Kepler supernova remnant

abstract:
  A new method to evaluate the dust-to-gas ratios in the Kepler SNR is
presented. Dust emission in the infrared and bremsstrahlung are calculated
consistently, considering that dust grains are collisionally heated by the gas
throughout the front and downstream of both the expanding and the reverse
shocks. The dust-to-gas ratios are determined by the ratio of the dust emission
bump and bremsstrahlung in the infrared. A maximum dust mass < 0.16 Mo is
calculated.


title:
Evidence for a multizone warm absorber in the XMM-Newton spectrum of
  Markarian 304

abstract:
  We present a XMM-Newton observation of Markarian 304, a Seyfert 1 galaxy at z
= 0.066. The EPIC data show that MKN 304 is affected by heavy (Nh ~10^{23}
cm{-2}) obscuration due to ionized gas. A two-phase warm absorber provides an
adequate parameterization of this gas. The ionization parameter of the two
components is \xi ~6 erg/cm2/s and \xi ~90 erg/cm2/s, respectively. The
observed continuum photon index (Gamma ~1.9) is typical for Seyfert 1 galaxies.
Two significant emission lines are detected at 0.57 keV and 6.4 keV,
respectively. The former is mostly likely due to He-like oxygen triplet
emission arising from an ionized plasma (maybe the warm absorber itself). The
latter is due to fluorescent emission of K-shell iron in a low-ionization state
(FeI--XV). The upper limit for the line width of sigma_{K\alpha} <0.18 keV most
likely rules out an origin in the inner parts of the accretion disk.
Interestingly, the strength of such line is consistent with the possibility
that the emission is produced in the warm absorber itself. However, a
substantial contribution from the torus is plausible too. We have also found a
weak (4% of the primary continuum) soft excess emission component. The presence
of this excess could be explained by either emission/scattering from a warm gas
or partial covering, or a combination of them.


title: Two new "very hot Jupiters" among the OGLE transiting candidates

abstract:
  As a result of a radial velocity follow-up of OGLE planetary transit
candidates in Carina, we report the discovery of two new transiting planets
with very short orbital periods: OGLE-TR-113 with m=1.35+-0.22 M_{Jup}, r=1.08
{+0.07}{-0.05} R_{Jup}, P=1.43 day, and OGLE-TR-132 with m=1.01+-0.31 M_{Jup},
r=1.15 {+0.80}{-0.13} R_{Jup}, P=1.69 day. These detections bring to three the
number of known "very hot Jupiters" (Jovian exoplanets like OGLE-TR-56 with
periods much smaller than 3 days), indicating that the absence of such planets
in radial velocity survey does not reflect an absolute limit.


title:
The Solar Neighborhood VIII: Discovery of New High Proper Motion Nearby
  Stars Using the SuperCOSMOS Sky Survey

abstract:
  Five new objects with proper motions between 1.0 arcsec/yr and 2.6 arcsec/yr
have been discovered via a new RECONS search for high proper motion stars
utilizing the SuperCOSMOS Sky Survey. The first portion of the search,
discussed here, is centered on the south celestial pole and covers declinations
-90 degrees to -57.5 degrees.
  Photographic photometry from SuperCOSMOS and JHKs near-infrared photometry
from 2MASS for stars nearer than 10 pc are combined to provide a suite of new
M_Ks-color relations useful for estimating distances to main sequence stars.
These relations are then used to derive distances to the new proper motion
objects as well as previously known stars with mu >= 1.0 arcsec/yr (many of
which have no trigonometric parallaxes) recovered during this phase of the
survey.
  Four of the five new stars have red dwarf colors, while one is a nearby white
dwarf. Two of the red dwarfs are likely to be within the RECONS 10 pc sample,
and the white dwarf probably lies between 15 and 25 pc. Among the 23 known
stars recovered during the search, there are three additional candidates for
the RECONS sample that have no trigonometric parallaxes.


title:
Asteroseismic Signatures of Helium gradients in Main-Sequence A Stars ;
  Application to the roAp Star HD60435

abstract:
  Asteroseismology is found to be a excellent tool for detecting
diffusion-induced helium gradients inside main-sequence A stars. Models have
been computed for 1.6 and 2.0 M$_{\odot}$ stars with pure helium diffusion, at
different ages, so that the helium gradient lies at different depths inside the
star. The adiabatic oscillation frequencies have been analysed and compared
with those of a model without diffusion. Clear signatures of the
diffusion-induced helium gradient are found in the so-called ``second
differences" : these frequency differences present modulations due to the
partial reflexion of the sound waves on the layer where the helium gradient
takes place. A tentative application to the roAp star HD60435, which presents
enough detected oscillation frequencies for the test to be possible, is very
encouraging. The results suggest the presence of a helium gradient inside the
star, which is consistent with the idea that the triggering of the oscillations
is due to the hydrogen $\kappa$-mechanism.


title: Modeling the Radio and X-ray Emission of SN 1993J and SN 2002ap

abstract:
  Modeling of radio and X-ray observations of supernovae interacting with their
circumstellar media are discussed, with special application to SN 1993J and SN
2002ap. We emphasize the importance of including all relevant physical
mechanisms, especially for the modeling of the radio light curves. The
different conclusions for the absorption mechanism (free-free or synchrotron
self-absorption), as well as departures from an $\rho \propto r^{-2}$ CSM, as
inferred by some authors, are discussed in detail. We conclude that the
evidence for a variation in the mass loss rate with time is very weak. The
results regarding the efficiencies of magnetic field generation and
relativistic particle acceleration are summarized.


title: Andromeda IX: A New Dwarf Spheroidal Satellite of M31

abstract:
  We report the discovery of a new dwarf spheroidal satellite of M31, Andromeda
IX, based on resolved stellar photometry from the Sloan Digital Sky Survey
(SDSS). Using both SDSS and public archival data we have estimated its distance
and other physical properties, and compared these to the properties of a
previously known dwarf spheroidal companion, Andromeda V, also observed by
SDSS. Andromeda IX is the lowest surface brightness galaxy found to date
(mu_{V} ~ 26.8 mag arcsec^-2), and at the distance we estimate from the
position of the tip of Andromeda IX's red giant branch, (m - M)_{0} ~ 24.5 (805
kpc), Andromeda IX would also be the faintest galaxy known (M_{V} ~ -8.3).


title: The absence of jets in cataclysmic variable stars

abstract:
  We show that the recently developed thermal model which successfully
describes how jets are launched by young stellar objects, when applied to
system containing disk-accreting white dwarfs naturally explain the otherwise
surprising absence of jets in cataclysmic variable stars. Our main argument
uses the crucial element of the thermal model, namely that the accreted
material is strongly shocked due to large gradients of physical quantities in
the boundary layer, and then cools on a time scale longer than its ejection
time from the disk. In our scenario the magnetic fields are weak, and serve
only to recollimate the outflow at large distances from the source, or to
initiate the shock, but not as a jet-driving agent. Using two criteria in that
model, for the shock formation and for the ejection of mass, we find the mass
accretion rate above which jets could be blown from accretion disks around
young stellar objects and white dwarfs. We find that these accretion mass rates
are ~10^{-7} Mo/yr, and ~10^{-6} Mo/yr for young stellar objects and white
dwarfs respectively. Considering the uncertainties of the model, these limits
could overestimate the critical value by a factor of ~10.


title:
New limits on the strong equivalence principle from two long-period
  circular-orbit binary pulsars

abstract:
  Following a brief review of the principles of the strong equivalence
principle (SEP) and tests for its violation in the strong and weak
gravitational field regimes, we present preliminary results of new tests using
two long-period binary pulsars: J0407+1607 and J2016+1947. PSR J0407+1607 is in
a 669-day orbit around a $\gapp 0.2$ M$_{\odot}$ companion, while J2016+1947 is
in a 635-day orbit around a $\gapp 0.3$ M$_{\odot}$ companion. The small
eccentricities of both orbits ($e \sim 10^{-3}$) mean that these systems reduce
previous limits on SEP violation by more than a factor of 4.