title: Semi-analytical dark matter halos and the Jeans equation

abstract:
  Although N-body studies of dark matter halos show that the density profiles,
rho(r), are not simple power-laws, the quantity rho/sigma^3, where sigma(r) is
the velocity dispersion, is in fact a featureless power-law over ~3 decades in
radius. In the first part of the paper we demonstrate, using the semi-analytic
Extended Secondary Infall Model (ESIM), that the nearly scale-free nature of
rho/sigma^3 is a robust feature of virialized halos in equilibrium. By
examining the processes in common between numerical N-body and semi-analytic
approaches, we argue that the scale-free nature of rho/sigma^3 cannot be the
result of hierarchical merging, rather it must be an outcome of violent
relaxation. The empirical results of the first part of the paper motivate the
analytical work of the second part of the paper, where we use rho/sigma^3
proportional to r^{-alpha} as an additional constraint in the isotropic Jeans
equation of hydrostatic equilibrium. Our analysis shows that the constrained
Jeans equation has different types of solutions, and in particular, it admits a
unique ``periodic'' solution with alpha=1.9444. We derive the analytic
expression for this density profile, which asymptotes to inner and outer
profiles of rho ~ r^{-0.78}, and rho ~ r^{-3.44}, respectively.


title: High Excitation Molecular Gas in the Magellanic Clouds

abstract:
  We present the first survey of submillimeter CO 4-3 emission in the
Magellanic Clouds. The survey is comprised of 15 6'x6' maps obtained using the
AST/RO telescope toward the molecular peaks of the Large and Small Magellanic
Clouds. We have used these data to constrain the physical conditions in these
objects, in particular their molecular gas density and temperature. We find
that there are significant amounts of molecular gas associated with most of
these molecular peaks, and that high molecular gas temperatures are pervasive
throughout our sample. We discuss whether this may be due to the low
metallicities and the associated dearth of gas coolants in the Clouds, and
conclude that the present sample is insufficient to assert this effect.


title:
Statistics of Magnification Perturbations by Substructure in the Cold
  Dark Matter Cosmological Model

abstract:
  We study the statistical properties of magnification perturbations by
substructures in strong lensed systems using linear perturbation theory and an
analytical substructure model including tidal truncation and a continuous
substructure mass spectrum. We demonstrate that magnification perturbations are
dominated by perturbers found within a tidal radius of an image, and that
sizable magnification perturbations may arise from small, coherent
contributions from several substructures within the lens halo. We find that the
root-mean-square (rms) fluctuation of the magnification perturbation is 10% to
20% and both the average and rms perturbations are sensitive to the mass
spectrum and density profile of the perturbers. Interestingly, we find that
relative to a smooth model of the same mass, the average magnification in
clumpy models is lower (higher) than that in smooth models for positive
(negative) parity images. This is opposite from what is observed if one assumes
that the image magnification predicted by the best-fit smooth model of a lens
is a good proxy for what the observed magnification would have been if
substructures were absent. While it is possible for this discrepancy to be
resolved via nonlinear perturbers, we argue that a more likely explanation is
that the assumption that the best-fit lens model is a good proxy for the
magnification in the absence of substructure is not correct. We conclude that a
better theoretical understanding of the predicted statistical properties of
magnification perturbations by CDM substructure is needed in order to affirm
that CDM substructures have been unambiguously detected.


title: A planetary system as the origin of structure in Fomalhaut's dust belt

abstract:
  The Sun and >15 percent of nearby stars are surrounded by dusty debris disks
that must be collisionally replenished by asteroids and comets, as the dust
would otherwise be depleted on <10 Myr timescales (ref. 1). Theoretical studies
show that disk structure can be modified by the gravitational influence of
planets (ref. 2-4), but the observational evidence is incomplete, at least in
part because maps of the thermal infrared emission from disks have low linear
resolution (35 AU in the best case; ref. 5). Optical images provide higher
resolution, but the closest examples (AU Mic and Beta Pic) are edge-on (ref.
6,7), preventing the direct measurement of azimuthal and radial disk structure
that is required for fitting theoretical models of planetary perturbations.
Here we report the detection of optical light reflected from the dust grains
orbiting Fomalhaut (HD 216956). The system is inclined 24 degrees away from
edge-on, enabling the measurement of disk structure around its entire
circumference, at a linear resolution of 0.5 AU. The dust is distributed in a
belt 25 AU wide, with a very sharp inner edge at a radial distance of 133 AU,
and we measure an offset of 15 AU between the belt's geometric centre and
Fomalhaut. Taken together, the sharp inner edge and offset demonstrate the
presence of planet-mass objects orbiting Fomalhaut.


title: The Arches Cluster - Evidence for a Truncated Mass Function?

abstract:
  We have analyzed high-resolution, adaptive optics (AO) HK observations of the
Arches cluster obtained with NAOS/CONICA. With a spatial resolution of 84 mas,
the cluster center is uniquely resolved. From these data the present-day mass
function (MF) of Arches is derived down to about 4 Msun. The integrated MF as
well as the core and 2nd annulus MFs are consistent with a turn-over at 6-7
Msun. This turn-over indicates severe depletion of intermediate and low-mass
stars in the Arches cluster, possibly caused by its evolution in the Galactic
Center environment. The Arches MF represents the first resolved observation of
a starburst cluster exhibiting a low-mass truncated MF. This finding has severe
implications for stellar population synthesis modelling of extragalactic
starbursts, the derivation of integrated properties such as the total mass of
star clusters in dense environments, the survival of low-mass remnants from
starburst populations, and chemical enrichment during starburst phases.


title:
Exploring the Physics of Type Ia Supernovae Through the X-ray Spectra of
  their Remnants

abstract:
  We present the results of an ongoing project to use the X-ray observations of
Type Ia Supernova Remnants to constrain the physical processes involved in Type
Ia Supernova explosions. We use the Tycho Supernova Remnant (SN 1572) as a
benchmark case, comparing its observed spectrum with models for the X-ray
emission from the shocked ejecta generated from different kinds of Type Ia
explosions. Both the integrated spectrum of Tycho and the spatial distribution
of the Fe and Si emission in the remnant are well reproduced by delayed
detonation models with stratified ejecta. All the other Type Ia explosion
models fail, including well-mixed deflagrations calculated in three dimensions.


title:
Models for Achromatic Light-Curve Breaks in GRB Afterglows: Jets,
  Structured Outflows, and Energy Injection

abstract:
  The steepening (break) of the power-law fall-off observed in the optical
emission of some GRB afterglows at epoch ~1 day is often attributed to a
collimated outflow (jet), undergoing lateral spreading. Wider opening GRB
ejecta with a non-uniform energy angular distribution (structured outflows) or
the cessation of energy injection in the afterglow can also yield light-curve
breaks.
  We determine the optical and X-ray light-curve decay indices and spectral
energy distribution slopes for 10 GRB afterglows with optical light-curve
breaks (980519, 990123, 990510, 991216, 000301, 000926, 010222, 011211, 020813,
030226), and use these properties to test the above models for light-curve
steepening. It is found that the optical breaks of six of these afterglows can
be accommodated by either energy injection or by structured outflows. In the
refreshed shock model, a wind-like stratification of the circumburst medium (as
expected for massive stars as GRB progenitors) is slightly favoured. A
spreading jet interacting with a homogeneous circumburst medium is required by
the afterglows 990510, 000301, 011211, and 030226. The optical pre- and
post-break decays of these four afterglows are incompatible with a wind-like
medium.
  The current sample of 10 afterglows with breaks suggests that the
distribution of the break magnitude (defined as the increase of the afterglow
decay exponent) is bimodal, with a gap at 1. If true, this bimodality favours
the structured outflow model, while the gap location indicates a homogeneous
circumburst environment.


title: The NII spectrum of the Orion Nebula

abstract:
  The predicted emission spectrum of NII is compared with observations of
permitted lines in the Orion nebula. Conventional nebular models show that the
intensities of the more intense lines can be explained by fluorescence of
starlight absorption with a N abundance that is consistent with forbidden
lines. Lines excited mostly by recombination on the other hand predict high N
abundances. The effects of stellar and nebular parameters and of the atomic
data on the predicted intensities are examined.


title: Dynamical Friction and Cooling Flows in Galaxy Clusters

abstract:
  We investigate a model of galaxy clusters in which the hot intracluster gas
is efficiently heated by dynamical friction (DF) of galaxies. We allow for both
subsonic and supersonic motions of galaxies and use the gravitational drag
formula in a gaseous medium presented by Ostriker (1999). The energy lost by
the galaxies is either redistributed locally or into a Gaussian centered on the
galaxy. We find that the condition of hydrostatic equilibrium and strict energy
balance yields a trivial isothermal solution T_iso, independent of radius, or
rising temperature distributions provided T_iso/gamma < T < T_iso, where gamma
is the adiabatic index of the gas. The isothermal temperature corresponds to
the usual scaling relation between the gas temperatures and the velocity
dispersions of galaxies. However the minimal temperature associated with the
rising solutions is ~ 0.5 T_vir, larger than that inferred from observations,
the radial distribution of galaxy masses notwithstanding. Heating by
supersonically moving galaxies cannot suppress thermal instability, although it
can lengthen the growth time up to the level comparable to the ages of clusters
when Mach number of galaxies is less than about two. We show using numerical
hydrodynamic simulations that DF-induced heating is generally unable to produce
stable equilibrium cores by evolving arbitrary non-equilibrium clusters,
although it can lengthen the cooling time. We conclude that DF-induced heating
alone is an unlikely solution to the cooling flow problem, although it can
still be an important heat supplier, considerably delaying cooling catastrophe.
We discuss other potential consequences of DF of galaxies in galaxy clusters.


title:
Kappa-mechanism excitation of retrograde mixed modes in rotating B-type
  stars

abstract:
  I examine the stability of retrograde mixed modes in rotating B-type stars.
These modes can be regarded as a hybrid between the Rossby modes that arise
from conservation of vorticity, and the Poincare modes that are gravity waves
modified by the Coriolis force. Using a non-adiabatic pulsation code based
around the traditional approximation, I find that the modes are unstable in
mid- to late-B type stars, due to the same iron-bump opacity mechanism usually
associated with SPB and $\beta$ Cep stars. At one half of the critical rotation
rate, the instability for $m=1...4$ modes spans the spectral types B4 to A0.
Inertial-frame periods of the unstable modes range from 100 days down to a
fraction of a day, while normalized growth rates can reach in excess of
$10^{-5}$.
  I discuss the relevance of these findings to SPB and pulsating Be stars, and
to the putative Maia class of variable star. I also outline some of the
questions raised by this discovery of a wholly-new class of pulsational
instability in early-type stars.


title:
Thermalization of Sputtered Particles as the Source of Diffuse Radiation
  from High Altitude Meteors

abstract:
  High altitude meteors become luminous at altitudes above $\sim$130 km, where
the standard ablation theory of meteor light production is not applicable. The
physical mechanism responsible for their glow has not been known. We present a
model that explains their existence, morphology and lightcurves. The model is
based on particles ejected from the meteoroid surface through the sputtering
process. The kinetic energy of such a sputtered particle is typically more than
1,000 times larger than the energy of particles in the surrounding atmosphere.
Thus the sputtered particle creates a cascade of collisions in the atmosphere
during thermalization. We show analytically that this process is capable of
producing enough light for detection. We also explain the observed relationship
between the beginning height of high altitude meteors and their maximum
brightness. In addition, meteors are modeled with a Monte Carlo code developed
specifically for this phenomenon. Theoretical images reproduce the observed
shapes and sizes of high altitude meteors. Their exact shape depends on the
relative angle between the meteor path and observer's line of sight.


title: Dust Emission by AGN and Starbursts

abstract:
  Present AGN and starburst models aiming to account for the observed infrared
SEDs consider a physical description of the dust and a solution of the
radiative transfer problem. MIR spectra obtained at different spatial scales
(SST-IRS, ISO and TIMMI2) are presented. They show that PAH bands are detected
in starburst regions but significantly reduced near the centre of AGN. This is
explained by examining the heating mechanism of PAHs after hard (FUV, X-ray)
photon interactions. Economic radiative transfer models of starbursts and AGN
are made available. The successful application of the starburst model is
demonstrated by fitting broad band data and detailed Spitzer spectra of
NGC7714. The AGN model is applied to ISO data of a sample of 68 radio galaxies
and quasars of the 3CR catalogue. Radiative transfer models of galaxies with
Hidden Broad Line Regions are shown. Their SED enable us to separate the
contributions from the dusty disc of the AGN and the starbursts. The composite
model is consistent with the unified scheme and the idea that the infrared
emission of AGN is dominated in the MIR and starbursts in the FIR. According to
the unified scheme, the observed diversity of AGN properties results from the
different orientations relative to our line of sight. The strong resonance of
silicate dust at 10mic is therefore, as expected, seen in absorption towards
many type-2 AGN. In type-1 AGN, it should be seen in emission because the hot
inner surface of the dust torus becomes visible. However, this has not been
observed so far, thus challenging the unification scheme or leading to exotic
modifications of the dust-torus model. Here the recent discovery of the 10mic
silicate feature in emission in luminous quasar spectra is reported.


title: SALT: a Spectral Adaptive Light curve Template for Type Ia Supernovae

abstract:
  We present a new method to parameterize Type Ia Supernovae (SN Ia)
multi-color light curves. The method was developed in order to analyze the
large number of SN Ia multi-color light curves measured in current
high-redshift projects. The technique is based on empirically modeling SN Ia
luminosity variations as a function of phase, wavelength, a shape parameter,
and a color parameter. The model is trained with a sample of well measured
nearby SN Ia and then tested with an independent set of supernovae by building
an optimal luminosity distance estimator combining the supernova rest-frame
luminosity, shape parameter and color reconstructed with the model. The
distances we measure using B- and V-band data show a dispersion around the
Hubble line comparable or lower than obtained with other methods. With this
model, we are able to measure distances using U- and B-band data with a
dispersion around the Hubble line of 0.16 +- 0.05.


title:
BRUSLIB and NETGEN: the Brussels nuclear reaction rate library and
  nuclear network generator for astrophysics

abstract:
  Nuclear reaction rates are quantities of fundamental importance in
astrophysics. Substantial efforts have been devoted in the last decades to
measure or calculate them. The present paper presents for the first time a
detailed description of the Brussels nuclear reaction rate library BRUSLIB and
of the nuclear network generator NETGEN so as to make these nuclear data
packages easily accessible to astrophysicists for a large variety of
applications. BRUSLIB is made of two parts. The first one contains the 1999
NACRE compilation based on experimental data for 86 reactions with (mainly)
stable targets up to Si. The second part of BRUSLIB concerns nuclear reaction
rate predictions calculated within a statistical Hauser-Feshbach approximation,
which limits the reliability of the rates to reactions producing compound
nuclei with a high enough level density. These calculations make use of global
and coherent microscopic nuclear models for the quantities entering the rate
calculations. The use of such models is utterly important, and makes the
BRUSLIB rate library unique.
  A description of the Nuclear Network Generator NETGEN that complements the
BRUSLIB package is also presented. NETGEN is a tool to generate nuclear
reaction rates for temperature grids specified by the user. The information it
provides can be used for a large variety of applications, including Big Bang
nucleosynthesis, the energy generation and nucleosynthesis associated with the
non-explosive and explosive hydrogen to silicon burning stages, or the
synthesis of the heavy nuclides through the s-, alpha- and r-, rp- or
p-processes.


title: Size distribution of circumstellar disks in the Trapezium cluster

abstract:
  In this paper we present results on the size distribution of circumstellar
disks in the Trapezium cluster as measured from HST/WFPC2 data. Direct diameter
measurements of a sample of 135 bright proplyds and 14 silhouettes disks
suggest that there is a single population of disks well characterized by a
power-law distribution with an exponent of -1.9 +- 0.3 between disk diameters
100-400 AU. For the stellar mass sampled (from late G to late M stars) we find
no obvious correlation between disk diameter and stellar mass. We also find
that there is no obvious correlation between disk diameter and the projected
distance to the ionizing Trapezium OB stars. We estimate that about 40% of the
disks in the Trapezium have radius larger than 50 AU. We suggest that the
origin of the Solar system's (Kuiper belt) outer edge is likely to be due to
the star formation environment and disk destruction processes
(photoevaporation, collisions) present in the stellar cluster on which the Sun
was probably formed. Finally, we identified a previously unknown proplyd and
named it 266-557, following convention.


title:
Abundances of Mn, Co and Eu in a sample of 20 F-G disk stars: the
  influence of hyperfine structure splitting

abstract:
  We present Mn, Co and Eu abundances for a sample of 20 disk F and G dwarfs
and subgiants with metallicities in the range -0.8 <= [Fe/H] <= +0.3. We
investigate the influence of hyperfine structure (HFS) on the derived
abundances of Mn and Co by using HFS data from different sources in the
literature, as well as calculated HFS from interaction factors A and B. Eu
abundances were obtained from spectral synthesis of one Eu II line that takes
into account HFS from a series of recent laboratory measurements. For the lines
analyzed in this study, we find that for manganese, the differences between
abundances obtained with different HFSs are no larger than 0.10 dex. Our cobalt
abundances are even less sensitive to the choice of HFS than Mn, presenting a
0.07 dex maximum difference between determinations with different HFSs.
However, the cobalt HFS data from different sources are significantly
different. Our abundance results for Mn offer an independent confirmation of
the results from Prochaska & McWilliam (2000), who favour type Ia supernovae as
the main nucleosynthesis site of Mn production, in contrast to trends of Mn
versus metallicity previously reported in the literature. For Co, we obtain
[Co/Fe] ~ 0.0 in the range -0.3 < [Fe/H] < +0.3 and [Co/Fe] rising to a level
of +0.2 when [Fe/H] decreases from -0.3 to -0.8, in disagreement with recent
results in the literature. The observed discrepancies may be attributed to the
lack of HFS in the works we used for comparison. Our results for Eu are in
accordance with low-mass type II supernovae being the main site of the
r-process nucleosynthesis.


title:
Fundamental Parameters of Low Mass X-ray Binaries II: X-Ray Persistent
  Systems

abstract:
  The determination of fundamental parameters in X-ray luminous (persistent)
X-ray binaries has been classically hampered by the large optical luminosity of
the accretion disc. New methods, based on irradiation of the donor star and
burst oscillations, provide the opportunity to derive dynamical information and
mass constraints in many persistent systems for the first time. These
techniques are here reviewed and the latest results presented.


title: Primary Energy Spectra and Elemental Composition. GAMMA Experiment

abstract:
  On the basis of the Extensive Air Shower data observed by the GAMMA
experiment the energy spectra and elemental composition of the primary cosmic
rays have been derived in the 1-100 PeV energy range. Reconstruction of the
primary energy spectra is carried out in the framework of the SIBYLL and QGSJET
interaction models and the hypothesis of the power-law steepening primary
energy spectra. All presented results are derived taking into account the
detector response, reconstruction uncertainties of EAS parameters and
fluctuation of EAS development.


title:
New multi-zoom method for N-body simulations: application to galaxy
  growth by accretion

abstract:
  In this work we focus on the properties of accretion onto galaxies. Through
numerical simulations we investigate the geometrical properties of accretion.
To span the scale range required in these simulations we have developed a new
numerical technique: the multi-zoom method. We run a series of Tree-SPH
simulations in smaller and smaller boxes at higher and higher mass resolution,
using data recorded at the previous level to account for the matter inflow and
the tidal field from outside matter. The code is parallelized using OpenMP. We
present a validation test to evaluate the robustness of the method: the pancake
collapse. We apply this new multizoom method to study the accretion properties.
Zooming in onto galaxies from a cosmological simulation, we select a sample of
10 well resolved galaxies (5000 baryonic particles or more). We sum up their
basic properties and plot a Tully-Fisher relation. We find that smooth
accretion of intergalactic cold gas dominates mergers for the mass growth of
galaxies at z < 2. Next we study the baryonic accretion rate which shows
different behaviours depending on the galaxy mass. The bias is also computed at
different radii and epochs. Then we present galactocentric angular maps for the
accretion integrated between z=2 and z=0, which reveal that accretion is highly
anisotropic. Average accretion rates plotted against galactocentric latitude
show a variety of behaviours. In general, accretion in the galactic plane is
favored, even more for baryonic matter than for dark matter.


title:
Discovery of a redshifted X-ray emission line in the symbiotic neutron
  star binary 4U 1700+24

abstract:
  We present the spectral analysis of an XMM-Newton observation of the X-ray
binary 4U 1700+24, performed during an outburst in August 2002. The EPIC-PN
spectrum above 1 keV can be modeled by a blackbody plus Comptonization model,
as in previous observations. At lower energies, however, we detect a prominent
soft excess, which we model with a broad Gaussian centered at ~0.5 keV. In the
high resolution RGS spectrum we detect a single emission line, centered at
19.19^{+0.05}_{-0.09} \AA. We discuss two possible interpretations for this
line: O VIII at redshift z=0.012^{+0.002}_{-0.004} or Ne IX at redshift z~0.4.


title: The Cosmological History of Accretion onto Supermassive Black Holes

abstract:
  It is argued that supermassive black holes in the nuclei of galaxies most
likely have grown coevally with their host dark matter halos. A calculation
based on Press-Schechter within this framework shows that the mean rate of
accretion of matter onto such black holes varies from a value about 0.003 of
the Eddington rate at the present epoch to a value around 0.08 at redshift 3.
The bulk of AGN evolution may be explained as a reflection of the diminishing
rate of accretion of material onto galaxies. The result is almost independent
of mass of host dark matter halo and is only weakly dependent on the values of
cosmological parameters. At high redshifts, z greater than about 5, black holes
in galaxies would have been accreting close to the Eddington limit, which is
likely to lead to galactic outflows being ubiquitous at those epochs.


title:
On metal-deficient barium stars and their link with yellow symbiotic
  stars

abstract:
  This paper addresses the question of why metal-deficient barium stars are not
yellow symbiotic stars (YSyS). Samples of (suspected) metal-deficient barium
(mdBa) stars and YSyS have been collected from the literature, and their
properties reviewed. It appears in particular that the barium nature of the
suspected mdBa stars needs to be ascertained by detailed abundance analyses.
Abundances are therefore derived for two of them, HD 139409 and HD 148897,
which reveal that HD 148897 should not be considered a barium star. HD 139409
is a mild barium star, with overabundances observed only for elements belonging
to the first s-process peak (Y and Zr). The evidence for binarity among mdBa
stars is then reviewed, using three different methods: (i) radial-velocity
variations (from CORAVEL observations), (ii) Hipparcos astrometric data, and
(iii) a method based on the comparison between the Hipparcos and Tycho-2 proper
motions. A first-time orbit is obtained for HIP 55852, whereas evidence for the
(so far unknown) binary nature of HIP 34795, HIP 76605, HIP 97874 and HIP
107478 is presented. Two stars with no evidence for binarity whatsoever (HIP
58596 and BD +3 2688) are candidates low-metallicity thermally-pulsing
asymptotic giant branch stars, as inferred from their large luminosities. The
reason why mdBa stars are not YSyS is suggested to lie in their different
orbital period distributions: mdBa stars have on average longer orbital periods
than YSyS, and hence their companion accretes matter at a lower rate, for a
given mass loss rate of the giant star. The definite validation of this
explanation should nevertheless await the determination of the orbital periods
for the many mdBa stars still lacking periods, in order to make the comparison
more significant.


title: Multi-wavelength observations of PKS 2155-304 with H.E.S.S

abstract:
  The High Energy Stereoscopic System (H.E.S.S.) has observed the
high-frequency peaked BL Lac object PKS2155-304 in 2003 between October 19 and
November 26 in Very High Energy (VHE) gamma-rays (E>160 GeV for these
observations). Observations were carried out simultaneously with the
Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer
satellite (RXTE), the Robotic Optical Transient Search Experiment (ROTSE) and
the Nancay decimetric radiotelescope (NRT). Intra-night variability is seen in
the VHE band, the source being detected with a high significance on each night
it was observed. Variability is also found in the X-ray and optical bands on
kilosecond timescales, along with flux-dependent spectral changes in the
X-rays. The average H.E.S.S. spectrum shows a very soft power law shape with a
photon index of 3.37+/-0.07(stat)+/-0.10(sys). The energy outputs in the 2-10
keV and in the VHE gamma-ray range are found to be similar, with the X-rays and
the optical fluxes at a level comparable to some of the lowest historical
measurements, indicating that PKS2155-304 was in a low or quiescent state
during the observations. Both a leptonic and a hadronic model are used to
derive source parameters from these observations.


title:
The intermediate-age open clusters Ruprecht 61, Czernik 32, NGC 2225 and
  NGC 2262

abstract:
  We present the first $BVI$ CCD photometry to $V=22.0$ of 4 fields centered on
the region of the southern Galactic star clusters Ruprecht~61, Czernik~32, NGC
2225 and NGC 2262 and of 4 displaced control fields. These clusters were never
studied before, and we provide for the first time estimates of their
fundamental parameters, namely radial extent, age, distance and reddening. We
find that the four clusters are all of intermediate age (around 1 Gyr), close
to the Sun and possess lower than solar metal abundance.


title:
Quasi-Periodic Oscillations Resonantly Induced on Spin-Induced
  Deformed-Disks of Neutron Stars

abstract:
  We consider the situation where a spin-induced wavy perturbation is present
on disks of neutron-star low-mass X-ray binaries. By non-linearly coupling with
the perturbation, some modes of disk oscillations resonantly interact with the
disks. We examine the resonant conditions under the assumption that the disks
are vertically isothermal. The results show that when the spin frequency has
some particular values, resonant coupling occurs at some radii. The modes and
frequencies of these resonant oscillations are summarized. Some of these
resonant oscillations seem to explain the frequencies of the observed kHz QPOs
in objects of which the spin frequency is known.


title:
A photometric study of the old open clusters Berkeley 73, Berkeley 75
  and Berkeley 25

abstract:
  CCD BVI photometry of the faint open clusters Berkeley~73, Berkeley~75 and
Berkeley~25 are presented. The two latter are previously unstudied clusters to
our knowledge. While Berkeley~73 is found to be of intermediate-age (about 1.5
Gyr old), Berkeley~75 and Berkeley~25 are two old clusters, with ages larger
than 3.0 Gyr. We provide also estimates of the clusters size. Very
interestingly, all these clusters turn out to lie far away from the Galactic
Center, at $R_{GC} \geq$ 16 kpc, and quite high onto the Galactic plane, at
$|Z_{\odot}| \geq 1.5$ kpc. They are therefore important targets to probe the
properties of the structure of the Galaxy in this direction, where the Canis
Major over-density has been recently discovered to be located.


title: Hypernovae, Black-Hole-Forming Supernovae, and First Stars

abstract:
  Recent studies of core-collapse supernovae have revealed the existence of two
distinct classes of massive supernovae (SNe): 1) very energetic SNe
(Hypernovae), whose kinetic energy (KE) exceeds $10^{52}$ erg, about 10 times
the KE of normal core-collapse SNe, and 2) very faint and low energy SNe (E <
0.5 $\times$ $10^{51}$ erg; Faint supernovae). These two classes of supernovae
are likely to be "black-hole-forming" supernovae with rotating or non-rotating
black holes. We compare their nucleosynthesis yields with the abundances of
extremely metal-poor (EMP) stars to identify the Pop III (or first) supernovae.
We show that the EMP stars, especially the C-rich type, are likely to be
enriched by black-hole-forming supernovae.


title: Large-Scale Anisotropy of EGRET Gamma Ray Sources

abstract:
  In the course of its operation, the EGRET experiment detected high-energy
gamma ray sources at energies above 100 MeV over the whole sky. In this
communication, we search for large-scale anisotropy patterns among the
catalogued EGRET sources using an expansion in spherical harmonics, accounting
for EGRET's highly non-uniform exposure. We find significant excess in the
quadrupole and octopole moments. This is consistent with the hypothesis that,
in addition to the galactic plane, a second mid-latitude (5^{\circ} < |b| <
30^{\circ}) population, perhaps associated with the Gould belt, contributes to
the gamma ray flux above 100 MeV.


title: The Aao/Ukst Supercosmos H-alpha Survey (SHS)

abstract:
  The UK Schmidt Telescope (UKST) of the Anglo-Australian Observatory completed
a narrow-band H-alpha plus [NII] 6548, 6584A survey of the Southern Galactic
Plane and Magellanic Clouds in late 2003. The survey, which was the last UKST
wide-field photographic survey, and the only one undertaken in a narrow band,
is now an on-line digital data product of the Wide-Field Astronomy Unit of the
Royal Observatory Edinburgh (ROE). The survey utilised a high specification,
monolithic H-alpha interference band-pass filter of exceptional quality. In
conjunction with the fine grained Tech-Pan film as a detector it has produced a
survey with a powerful combination of area coverage (4000 square degrees),
resolution (~1 arcsecond) and sensitivity (<=5 Rayleighs), reaching a depth for
continuum point sources of R~20.5. The main survey consists of 233 individual
fields on a grid of centres separated by 4 degrees at declinations below +2
degrees and covers a swathe approximately 20 degrees wide about the Southern
Galactic Plane. The original survey films were scanned by the SuperCOSMOS
measuring machine at the Royal Observatory, Edinburgh to provide the on-line
digital atlas called the SuperCOSMOS H-alpha Survey (SHS). We present the
background to the survey, the key survey characteristics, details and examples
of the data product, calibration process, comparison with other surveys and a
brief description of its potential for scientific exploitation.


title: Hubble Space Telescope Spectroscopy of the Balmer lines in Sirius B

abstract:
  Sirius B is the nearest and brightest of all white dwarfs, but it is very
difficult to observe at visible wavelengths due to the overwhelming scattered
light contribution from Sirius A. However, from space we can take advantage of
the superb spatial resolution of the Hubble Space Telescope to resolve the A
and B components. Since the closest approach in 1993, the separation between
the two stars has become increasingly favourable and we have recently been able
to obtain a spectrum of the complete Balmer line series for Sirius B using
HST?s Space Telescope Imaging Spectrograph (STIS). The quality of the STIS
spectra greatly exceed that of previous ground-based spectra, and can be used
to provide an important determination of the stellar temperature (Teff =
25193K) and gravity (log g = 8.556). In addition we have obtained a new, more
accurate, gravitational red-shift of 80.42 +/- 4.83 km s-1 for Sirius B.
Combining these results with the photometric data and the Hipparcos parallax we
obtain new determinations of the stellar mass for comparison with the
theoretical mass-radius relation. However, there are some disparities between
the results obtained independently from log g and the gravitational redshift
which may arise from flux losses in the narrow 50x0.2arcsec slit. Combining our
measurements of Teff and log g with the Wood (1995) evolutionary mass-radius
relation we get a best estimate for the white dwarf mass of 0.978 M. Within the
overall uncertainties, this is in agreement with a mass of 1.02 M obtained by
matching our new gravitational red-shift to the theoretical M/R relation.


title:
Constraining the extra heating of the Diffuse Ionized Gas in the Milky
  Way

abstract:
  The detailed observations of the diffuse ionized gas through the emission
lines H$\alpha$, [NII], and [SII] in the Perseus Arm of our Galaxy by the
Wisconsin H$\alpha$ Mapper (WHAM)--survey challenge photoionization models.
They have to explain the observed rise in the line ratios [NII]/H$\alpha$ and
[SII]/H$\alpha$. The models described here consider for the first time the
detailed observational geometry toward the Perseus Arm. The models address the
vertical variation of the line ratios up to height of 2 kpc above the midplane.
The rising trends of the line ratios are matched. The increase in the line
ratios is reflected in a rise of the temperature of the gas layer. This is due
to the progressive hardening of the radiation going through the gas. However an
extra heating above photoionization is needed to explain the absolute values.
Two different extra heating rates are investigated which are proportional to
$n^0$ and $n^1$. The models show that a combination of both are best to explain
the data, where the extra heating independent of density is dominant for z $>$
0.8 kpc.


title:
Detection of gravity waves by phase modulation of the light from a
  distant star

abstract:
  We propose a novel method for detecting gravitational waves (GW), where a
light signal emitted from a distant star interacts with a local (also distant)
GW source and travels towards the Earth, where it is detected. While traveling
in the field of the GW, the light acquires specific phase modulation (which we
account in the eikonal approximation). This phase modulation can be considered
as a coherent spreading of the given initial photons energy over a set of
satellite lines, spaced at the frequency of GW (from quantum point of view it
is multi-graviton absorption and emission processes). This coherent state of
photons with the energy distributed among the set of equidistant lines, can be
analyzed and identified on Earth either by passing the signal through a
Fabry-Perot filter or by monitoring the intensity-intensity correlations at
different times.


title: Submm line imaging of Orion-KL with the Submillimeter Array

abstract:
  We present the first submm (865mum) imaging spectral line survey at one
arcsecond resolution conducted with the Submillimeter Array toward Orion-KL.
Within the 2x2 GHz bandpasses (lower and upper sidebands, 337.2-339.2GHz and
347.2-349.2GHz), we find about 145 spectral lines from 13 species, 6
isotopologues, and 5 vibrational excited states. Most nitrogen-bearing
molecules are strong toward the hot core, whereas the oxygen-bearing molecules
peak toward the south-west in the so-called compact ridge. Imaging of spectral
lines is shown to be an additional tool to improve the identifications of
molecular lines. Arcsecond spatial resolution allows us to distinguish the
molecular line emission of the sources I and n from that of the hot core. The
only molecular species detected strongly toward source I is SiO, delineating
mainly the collimated north-east south-west low-velocity outflow. The two
positions close to source I, which have previously been reported to show maser
emission in the v=0 28SiO(1-0) and (2-1) lines, show no detectable maser
emission in the v=0 28SiO(8-7) line at our spatial resolution. SiO is weak
toward source n, and thus source n may not currently be driving a molecular
outflow. CH$_3$OH is the molecule with the highest number of identified lines
(46) in this spectral window. This ``line forest'' allows us to estimate
temperatures in the region, and we find temperatures between 50 and 350K, with
the peak temperatures occurring toward the hot core. The detection of strong
vibrational excited line emission from the submm continuum peak SMA1 supports
the interpretation that the source SMA1 is likely of protostellar nature.


title:
Demonstration of the applicability of 3D Slicer to Astronomical Data
  Using 13CO and C18O Observations of IC348

abstract:
  3D Slicer, a brain imaging and visualization computer application developed
at Brigham and Women's Hospital's Surgical Planning Lab, was used to visualize
the IC 348 star-forming complex in Perseus in RA-DEC-Velocity space. This
project is part of a collaboration between Harvard University's Astronomy
Department and Medical School, and serves as a proof-of-concept technology
demonstration for Harvard's Institute for Innovative Computing (IIC). 3D Slicer
is capable of displaying volumes (data cubes), slices in any direction through
the volume, 3D models generated from the volume, and 3D models of label maps.
The 3D spectral line maps of IC 348 were created using 13CO and C18O data
collected at the FCRAO (Five College Radio Astronomy Observatory). The 3D
visualization makes the identification of the cloud's inner dense cores and
velocity structure components easier than current conventional astronomical
methods. It is planned for 3D Slicer to be enhanced with astrophysics-specific
features resulting in an astronomical version to be available online through
the IIC and in conjunction with the National Virtual Observatory (NVO).


title:
Physical Conditions in the Dwarf Local Group Irregular Galaxy IC10. I-
  Diffuse Ionized Gas

abstract:
  A detailed analysis on the physical conditions of the Interstellar Medium in
the main body of the Local Group dwarf irregular galaxy IC 10 is carried out
using long-slit spectroscopy. Maps of the excitation, the H$\alpha$ flux,
[NII]/H$\alpha$ and [SII]/H$\alpha$ are presented. The Diffuse Ionized Gas
inside the galaxy is studied. We found that the spectral characteristics are
not similar to those for spiral galaxies: the values of the ratios
[NII]/H$\alpha$ and [SII]/H$\alpha$ are not as large as in spiral galaxies but
the excitation is much larger. These values, especially the large excitation,
can be explained by proposing an extra source of ionization. Different sources
are studied but any of the models at hand could be really fitted except a
combination of photons leaking from the HII regions in addition to the
ionization provided by the WR stars present in this galaxy. Shocks are not
needed for explaining the line intensity ratios except in a small part in the
west side of the galaxy.


title: Precession of the Isolated Neutron Star PSR B1828-11

abstract:
  Stairs, Lyne & Shemar have found that arrival time residuals from PSR
B1828-11 vary periodically with a period of 500 days. This behavior can be
accounted for by precession of the radiopulsar, an interpretation that is
reinforced by the detection of variations in its pulse profile on the same
timescale. Here, we model the period residuals from PSR B1828-11 in terms of
precession of a triaxial rigid body. We include two contributions to the
residuals: (i) the geometric effect, which arises because the times at which
the pulsar emission beam points toward the observer varies with precession
phase; (ii) the spindown contribution, which arises from any dependence of the
spindown torque acting on the pulsar on the angle between its spin and magnetic
axes. We use the data to probe numerous properties of the pulsar, most notably
its shape, and the dependence of its spindown torque on the angle between its
spin and magnetic axes, for which we assume a sum of a spin-aligned component
(with a weight 1-a) and a dipolar component perpendicular to the magnetic beam
axis (weight a), rather than the vacuum dipole torque (a=1). We find that a
variety of shapes are consistent with the residuals, with a slight statistical
preference for a prolate star. Moreover, a range of torque possibilities fit
the data equally well, with no strong preference for the vacuum model. In the
case of a prolate star we find evidence for an angle-dependent spindown torque.
Our results show that the combination of geometrical and spin-down effects
associated with precession can account for the principal features of PSR
B1828-11's timing behavior, without fine tuning of the parameters.


title:
The Extended Chandra Deep Field-South Survey. Chandra Point-Source
  Catalogs

abstract:
  We present Chandra point-source catalogs for the Extended Chandra Deep
Field-South (E-CDF-S) survey. The E-CDF-S consists of four contiguous 250 ks
Chandra observations covering an approximately square region of total solid
angle ~0.3 deg^2, which flank the existing ~1 Ms Chandra Deep Field-South
(CDF-S). The survey reaches sensitivity limits of 1.1 X 10^-16 erg/cm^2/s and
6.7 X 10^-16 erg/cm^2/s for the 0.5-2.0 keV and 2-8 keV bands, respectively. We
detect 762 distinct X-ray point sources within the E-CDF-S exposure; 589 of
these sources are new (i.e., not previously detected in the ~1 Ms CDF-S). This
brings the total number of X-ray point sources detected in the E-CDF-S region
to 915 (via the E-CDF-S and ~1 Ms CDF-S observations). Source positions are
determined using matched-filter and centroiding techniques; the median
positional uncertainty is ~0.35". The basic X-ray and optical properties of
these sources indicate a variety of source types, although absorbed active
galactic nuclei (AGNs) seem to dominate. In addition to our main Chandra
catalog, we constructed a supplementary source catalog containing 33 lower
significance X-ray point sources that have bright optical counterparts (R<23).
These sources generally have X-ray-to-optical flux ratios expected for normal
and starburst galaxies, which lack a strong AGN component. We present basic
number-count results for our main Chandra catalog and find good agreement with
the ~1 Ms CDF-S for sources with 0.5-2.0 keV and 2-8 keV fluxes greater than 3
X 10^-16 erg/cm^2/s and 1 X 10^-15 erg/cm^2/s, respectively. Furthermore, three
extended sources are detected in the 0.5-2.0 keV band, which are found to be
likely associated with galaxy groups or poor clusters at z ~ 0.1-0.7; these
have typical rest-frame 0.5-2.0 keV luminosities of (1-5) X 10^42 erg/s.


title: The X-ray Spectral Properties of SCUBA Galaxies

abstract:
  Deep SCUBA surveys have uncovered a large population of massive submm
galaxies (SMGs) at z>~1. Although it is generally believed that these galaxies
host intense star-formation activity, there is growing evidence that a
substantial fraction also harbor an AGN. We present here possibly the strongest
evidence for this viewpoint to date: the combination of ultra-deep X-ray
observations (the 2 Ms CDF-N) and deep Keck spectroscopic data. We find that
the majority (~75%) of the spectroscopically identified SMGs host AGN activity;
the other ~25% have X-ray properties consistent with star formation (X-ray
derived SFRs of ~1300-2700 solars/yr). The AGNs have properties generally
consistent with those of nearby luminous AGNs (L_X~1E43-3E44) and the majority
(~80%) are heavily obscured. We construct composite rest-frame 2-20 keV spectra
for three different obscuration classes. An ~1 keV equivalent width FeK-alpha
emission line is seen in the composite X-ray spectrum of the most heavily
obscured AGNs (N_H>5x10^{23}), suggesting Compton-thick or near Compton-thick
absorption. Even taking into account the effects of absorption, we find that
the average X-ray-FIR ratio of the AGN-classified SMGs is approximately one
order of magnitude below that found for typical quasars. This result suggests
that intense star-formation activity dominates the bolometric output; however,
we also explore whether the X-ray-FIR ratio is intrinsically less than that
found for typical quasars and postulate that some SMGs may be AGN dominated. We
investigate the growth of massive black holes, discuss prospects for deeper
observations, and explore the potential of the next generation of X-ray
observatories. (ABRIDGED).


title:
Constraints on the Proper Motion of the Andromeda Galaxy Based on the
  Survival of Its Satellite M33

abstract:
  A major uncertainty in the dynamical history of the local group of galaxies
originates from the unknown transverse speed of the Andromeda galaxy (M31)
relative to the Milky Way. We show that the recent VLBA measurement of the
proper motion of Andromeda's satellite, M33, severely constrains the possible
values of M31's proper motion. The condition that M33's stellar disk will not
be tidally disrupted by either M31 or the Milky Way over the past 10 billion
years, favors a proper motion amplitude of 100+-20km/s for M31 with the
quadrant of a negative velocity component along Right Ascension and a positive
component along Declination strongly ruled-out. This inference can be tested by
future astrometric measurements with SIM, GAIA, or the SKA. Our results imply
that the dark halos of Andromeda and the Milky Way will pass through each other
within the next 5-10 billion years.


title:
Outflows in Infrared-Luminous Starbursts at z < 0.5. I. Sample, NaI D
  Spectra, and Profile Fitting

abstract:
  We have conducted a spectroscopic survey of 78 starbursting infrared-luminous
galaxies at redshifts up to z = 0.5. We use moderate-resolution spectroscopy of
the NaI D interstellar absorption feature to directly probe the neutral phase
of outflowing gas in these galaxies. Over half of our sample are ultraluminous
infrared galaxies that are classified as starbursts; the rest have infrared
luminosities in the range log(L_IR/L_sun) = 10.2 - 12.0. The sample selection,
observations, and data reduction are described here. The absorption-line
spectra of each galaxy are presented. We also discuss the theory behind
absorption-line fitting in the case of a partially-covered, blended absorption
doublet observed at moderate-to-high resolution, a topic neglected in the
literature. A detailed analysis of these data is presented in a companion
paper.


title:
Outflows in Infrared-Luminous Starbursts at z < 0.5. II. Analysis and
  Discussion

abstract:
  We have performed an absorption-line survey of outflowing gas in 78
starburst-dominated, infrared-luminous galaxies. This is the largest study of
superwinds at z < 3. Superwinds are found in almost all infrared-luminous
galaxies, and changes in detection rate with SFR--winds are found twice as
often in ultraluminous infrared galaxies (ULIRGs) as in less-luminous
galaxies--reflect different wind geometries. The maximum velocities we measure
are 600 km/s, though most of the outflowing gas has lower velocities (100-200
km/s). (One galaxy has velocities exceeding 1000 km/s.) Velocities in LINERs
are higher than in HII galaxies, and outflowing ionized gas often has higher
velocities than the neutral gas. Wind properties (velocity, mass, momentum, and
energy) scale with galaxy properties (SFR, luminosity, and galaxy mass),
consistent with ram-pressure driving of the wind. Wind properties increase
strongly with increasing galactic mass, contrary to expectation. These
correlations flatten at high SFR (> 10-100 M_sun/yr), luminosities, and masses.
This saturation is due to a lack of gas remaining in the wind's path, a common
neutral gas terminal velocity, and/or a decrease in the efficiency of
thermalization of the supernovae energy. It means that mass entrainment
efficiency, rather than remaining constant, declines in galaxies with SFR > 10
M_sun/yr and M_K < -24. Half of our sample consists of ULIRGs, which host as
much as half of the star formation in the universe at z > 1. The powerful,
ubiquitous winds we observe in these galaxies imply that superwinds in massive
galaxies at redshifts above unity play an important role in the evolution of
galaxies and the intergalactic medium.


title: The Survival of Planetary Nebulae in the Intracluster Medium

abstract:
  The stellar population stripped from galaxies in clusters evolve under the
extreme conditions imposed by the intracluster (IC) medium. Intracluster stars
generally suffer very high systemic velocities, and evolve within a rarefied
and extremely hot IC medium. We present numerical simulations which aim to
explore the evolution and survival of IC Asymptotic Giant Branch (AGB)
envelopes and Planetary Nebula (PN) shells. Our models reflect the evolution of
a low-mass star under the observed conditions in the Virgo IC medium. We find
that the integrated hydrogen-recombination line emission of a PN is dominated
by the inner dense shell, whose evolution is unaffected by the environment. Ram
pressure stripping affects mainly the outermost IC PN shell, which hardly
influences the emission when the PN is observed as a point source. More
importantly, we find that a PN with progenitor mass of 1 Msun fades to ~30% and
10% of its maximum emission, in 5,000 and 10,000 yr respectively, disclosing an
actual PN lifetime t_PN several times shorter to what is usually adopted
(25,000 yr). This result affects the theoretical calculation of the
luminosity-specific density of IC PNe, which scales with t_PN. For t_PN=10,000
yr, our more conservative estimate, we obtain that the luminosity-specific
density of PNe is in fair agreement with the value obtained from Red Giants.
With our more realistic PN lifetime we infer a higher fraction (above 15%) of
IC starlight in the Virgo core than current estimates.


title: The STACEE Ground-Based Gamma-Ray Detector

abstract:
  We describe the design and performance of the Solar Tower Atmospheric
Cherenkov Effect Experiment (STACEE) in its complete configuration. STACEE uses
the heliostats of a solar energy research facility to collect and focus the
Cherenkov photons produced in gamma-ray induced air showers. The light is
concentrated onto an array of photomultiplier tubes located near the top of a
tower. The large Cherenkov photon collection area of STACEE results in a
gamma-ray energy threshold below that of previous ground-based detectors.
STACEE is being used to observe pulsars, supernova remnants, active galactic
nuclei, and gamma-ray bursts.


title: Effect of Photometric Redshift Uncertainties on Weak Lensing Tomography

abstract:
  We perform a systematic analysis of the effects of photometric redshift
uncertainties on weak lensing tomography. We describe the photo-z distribution
with a bias and Gaussian scatter that are allowed to vary arbitrarily between
intervals of dz = 0.1 in redshift.While the mere presence of bias and scatter
does not substantially degrade dark energy information, uncertainties in both
parameters do. For a fiducial next-generation survey each would need to be
known to better than about 0.003-0.01 in redshift for each interval in order to
lead to less than a factor of 1.5 increase in the dark energy parameter errors.
The more stringent requirement corresponds to a larger dark energy parameter
space, when redshift variation in the equation of state of dark energy is
allowed.Of order 10^4-10^5 galaxies with spectroscopic redshifts fairly sampled
from the source galaxy distribution will be needed to achieve this level of
calibration. If the sample is composed of multiple galaxy types, a fair sample
would be required for each. These requirements increase in stringency for more
ambitious surveys; we quantify such scalings with a convenient fitting formula.
No single aspect of a photometrically binned selection of galaxies such as
their mean or median suffices, indicating that dark energy parameter
determinations are sensitive to the shape and nature of outliers in the photo-z
redshift distribution.


title:
The distribution and kinematics of early high-sigma peaks in present-day
  haloes: implications for rare objects and old stellar populations

abstract:
  We show that the hierarchical assembly of cold dark matter (CDM) haloes
preserves the memory of the initial conditions. Using N-body cosmological
simulations, we demonstrate that the present-day spatial distribution and
kinematics of objects that formed within early (z > 10) protogalactic systems
(old stars, satellite galaxies, globular clusters, massive black holes, etc.)
depends mostly on the rarity of the peak of the primordial density field which
they originally belonged to. Only for objects forming at lower redshifts the
exact formation site within the progenitor halo (e.g. whether near the center
or in an extended disk) becomes important. In present-day haloes, material from
the rarer early peaks is more centrally concentrated and falls off more steeply
with radius compared to the overall mass distribution, it has a lower velocity
dispersion, moves on more radial orbits, and has a more elongated shape.
Population II stars that formed within protogalactic haloes collapsing from
>2.5 sigma fluctuations would follow today a r^{-3.5} density profile with a
half-light radius of 17 kpc and a velocity anisotropy that increases from
isotropic in the inner regions to nearly radial at the halo edge. This agrees
well with the radial velocity dispersion profile of Galaxy halo stars from
Battaglia et al. (2005) and with the anisotropic orbits of nearby halo stars.


title: Variation in the Scattering Shroud Surrounding Markarian 231

abstract:
  We present a detailed study of the nuclear structure of the highly polarized
broad absorption line quasar, Mrk 231, through a multiwavelength campaign of
Chandra observations, optical spectroscopy, optical spectropolarimetry, and
imaging polarimetry. This campaign was designed to extend the 40 ks Chandra
study of Gallagher et al. and the optical and UV spectropolarimetric study of
Smith et al. to probe variability on multiple time scales. As direct emission
from the nucleus is heavily obscured at optical through X-ray wavelengths, the
detailed study of scattered emission has lead to insights into the stratified
and complex central region of this active galaxy. Though significant continuum
variability is not detected in any of the three new 40 ks Chandra observations,
we investigate FeKalpha emission features in the individual and combined
spectra. Comparing echelle spectra of the NaI D absorption lines with the
literature, we show that one system disappeared in 2000 only to reappear in
later epochs. Notably, we detect a large decrease in polarization across the
entire optical spectrum of Mrk 231 from 1995 to 2003. Though the polarization
fraction fell, e.g., from 4% to 3% at about 6000 Angstroms, the polarization
position angle spectrum remained unchanged. The optical polarization behavior
is consistent with a decrease in the flux scattered by circumnuclear material
on spatial scales where the broad-line region is resolved by the scattering
material. Ultraviolet imaging polarimetry of Mrk 231 by HST sets an upper limit
on the distance between the active nucleus and the scattering regions of <20
pc.


title: Two Body Relaxation in Simulated Cosmological Haloes

abstract:
  This paper aims at quantifying discreetness effects, born of finite particle
number, on the dynamics of dark matter haloes forming in the context of
cosmological simulations. By generalising the standard calculation of two body
relaxation to the case when the size and mass distribution are variable, and
parametrising the time evolution using established empirical relations, we find
that the dynamics of a million particle halo is noise-dominated within the
inner percent of the final virial radius. Far larger particle numbers (~ 10^8)
are required for the RMS perturbations to the velocity to drop to the 10 %
level there. The radial scaling of the relaxation time is simple and strong:
t_relax ~ r^2, implying that numbers >> 10^8 are required to faithfully model
the very inner regions; artificial relaxation may thus constitute an important
factor, contributing to the contradictory claims concerning the persistence of
a power law density cusp to the very centre. The cores of substructure haloes
can be many relaxation times old. Since relaxation first causes their expansion
before recontraction occurs, it may render them either more difficult or easier
to disrupt, depending on their orbital parameters. It may thus modify the
characteristics of the subhalo distribution and effects of interactions with
the parent. We derive simple closed form formulas for the characteristic
relaxation times, as well as for the weak N-scaling reported by Diemand et al.
when the main contribution comes from relaxing subhaloes (abridged).


title: Using Fuzzy Logic for Automatic Analysis of Astronomical Pipelines

abstract:
  Fundamental astronomical questions on the composition of the universe, the
abundance of Earth-like planets, and the cause of the brightest explosions in
the universe are being attacked by robotic telescopes costing billions of
dollars and returning vast pipelines of data. The success of these programs
depends on the accuracy of automated real time processing of the astronomical
images. In this paper the needs of modern astronomical pipelines are discussed
in the light of fuzzy-logic based decision-making. Several specific fuzzy-logic
algorithms have been develop for the first time for astronomical purposes, and
tested with excellent results on data from the existing Night Sky Live sky
survey.


title:
An approach toward the successful supernova explosion by physics of
  unstable nuclei

abstract:
  We study the explosion mechanism of collapse-driven supernovae by numerical
simulations with a new nuclear EOS based on unstable nuclei. We report new
results of simulations of general relativistic hydrodynamics together with the
Boltzmann neutrino-transport in spherical symmetry. We adopt the new data set
of relativistic EOS and the conventional set of EOS (Lattimer-Swesty EOS) to
examine the influence on dynamics of core-collapse, bounce and shock
propagation. We follow the behavior of stalled shock more than 500 ms after the
bounce and compare the evolutions of supernova core.


title:
Postbounce evolution of core-collapse supernovae: Long-term effects of
  equation of state

abstract:
  We study the evolution of supernova core from the beginning of gravitational
collapse of a 15Msolar star up to 1 second after core bounce. We present
results of spherically symmetric simulations of core-collapse supernovae by
solving general relativistic neutrino-radiation-hydrodynamics in the implicit
time-differencing. We aim to explore the evolution of shock wave in a long term
and investigate the formation of protoneutron star together with supernova
neutrino signatures. These studies are done to examine the influence of
equation of state (EOS) on the postbounce evolution of shock wave in the late
phase and the resulting thermal evolution of protoneutron star. We make a
comparison of two sets of EOS, that is, by Lattimer and Swesty (LS-EOS) and by
Shen et al.(SH-EOS). We found that, for both EOSs, the core does not explode
and the shock wave stalls similarly in the first 100 milliseconds after bounce.
The revival of shock wave does not occur even after a long period in either
cases. However, the recession of shock wave appears different beyond 200
milliseconds after bounce, having different thermal evolution of central core.
A more compact protoneutron star is found for LS-EOS than SH-EOS with a
difference in the central density by a factor of ~2 and a difference of ~10 MeV
in the peak temperature. Resulting spectra of supernova neutrinos are different
to the extent that may be detectable by terrestrial neutrino detectors.


title: Discovery of a widely separated binary system of very low mass stars

abstract:
  We report our discovery of a nearby wide binary system, LP 714-37 AB.
Phan-Bao et al. identified LP 714-37 as a mid-M dwarf during a
cross-identification of the NLTT and DENIS catalogues. Our CCD images resolve
the system into a binary with a projected angular separation of 1.8 arcsec, or
33 AU, and low-resolution optical spectra give spectral types of M5.5 (LP
714-37A) and M7.5 (LP 714-37B). This makes LP 714-37 AB one of very few widely
separated (separation > 30 AU) very low-mass binary systems known in the field,
and we discuss it in the context of the multiplicity properties of very
low-mass stars and brown dwarfs.


title:
The Ital-FLAMES survey of the Sagittarius dwarf Spheroidal galaxy. I.
  Chemical abundances of bright RGB stars

abstract:
  We present iron and $\alpha$ element (Mg, Ca, Ti) abundances for a sample of
15 Red Giant Branch stars belonging to the main body of the Sagittarius dwarf
Spheroidal galaxy. Abundances have been obtained from spectra collected using
the high resolution spectrograph FLAMES-UVES mounted at the VLT. Stars of our
sample have a mean metallicity of [Fe/H]=-0.41$\pm$0.20 with a metal poor tail
extending to [Fe/H]=-1.52. The $\alpha$ element abundance ratios are slightly
subsolar for metallicities higher than [Fe/H]\gtsima-1, suggesting a slow star
formation rate. The [$\alpha$/Fe] of stars having [Fe/H]$<$-1 are compatible to
what observed in Milky Way stars of comparable metallicity.


title:
Fully Degenerate Self-Gravitating Fermionic Dark Matter: Implications to
  the Density Profile of the Cluster of Galaxies A1689, and the Mass Hierarchy
  of Black Holes

abstract:
  Equilibrium configurations of weakly interacting fully degenerate fermionic
dark matter are considered at various scales in the Universe. We treat the
general situations for the gravity from Newtonian to general relativity and the
degeneracy from nonrelativistic to relativistic. A dimensionless equilibrium
configuration is specified by a single parameter regardless of particle
properties, the Fermi velocity at the center, and the scalings of mass and
length are specified by the rest mass and statistical weight of the dark matter
particle. We focus our attention to the flat-top nature of the mass column
density profile of the cluster of galaxies, A1689, recently reported by
Broadhurst et al. using gravitational lensing. We convert the column density
profile to a volume density profile assuming spherical symmetry and derive a 3D
encircled mass profile of A1689, which is compared with the model profiles of
degenerate fermion structures. The flat-top profile is reproduced. The
corresponding fermion mass ranges from 2 eV to 30 eV depending on the actual
scale of the degenerate structure. If massive neutrinos are the dominant dark
matter, the rest mass will be about 4.7 or 2.3 eV respectively for Majorana or
Dirac neutrinos. The mass and size of the degenerate structure are
$10^{14}M_\odot$ and 100 kpc for Majorana neutrinos, and
5$\times10^{14}M_\odot$ and 300 kpc for Dirac neutrinos. If we identify the
fermions as heavier sterile neutrinos, they yield the characteristic mass
hierarchy of black holes; giant black hole at the center of a galaxy and the
intermediate mass black holes. Thus we propose the possibility that the mass
hierarchy of fermions determines that of black holes in the Universe.


title: Exotica in rotating compact stars

abstract:
  The determination of mass and radius of a single neutron star EXO 0748-676
has been reported recently. Also, the estimate of radius from the measurement
of moment of inertia of pulsar A in double pulsar system PSR J0737-3039 would
be possible in near future. Here we construct models of static and uniformly
rotating neutron stars involving exotic matter and compare our theoretical
calculations with the recent findings from observations to probe dense matter
in neutron stars.


title: A model for the infrared dust emission from forming galaxies

abstract:
  In the early epoch of galaxy evolution, dust is only supplied by supernovae
(SNe). With the aid of a new physical model of dust production by SNe developed
by Nozawa et al. (2003) (N03), we constructed a model of dust emission from
forming galaxies on the basis of the theoretical framework of Takeuchi et al.
(2003) (T03). N03 showed that the produced dust species depends strongly on the
mixing within SNe. We treated both unmixed and mixed cases and calculated the
infrared (IR) spectral energy distribution (SED) of forming galaxies for both
cases. Our model SED is less luminous than the SED of T03 model by a factor of
2-3. The difference is due to our improved treatment of UV photon absorption
cross section, as well as different grain size and species newly adopted in
this work. The SED for the unmixed case is found to have an enhanced near to
mid-IR (N-MIR) continuum radiation in its early phase of the evolution (age <
10^{7.25} yr) compared with that for the mixed case. The strong N--MIR
continuum is due to the emission from Si grains, which only exist in the
species of the unmixed dust production. We also calculated the IR extinction
curves for forming galaxies. Then we calculated the SED of a local starbursting
dwarf galaxy SBS 0335-052. Our present model SED naturally reproduced the
strong N--MIR continuum and the lack of cold FIR emission of SBS 0335-052. We
found that only the SED of unmixed case can reproduce the NIR continuum of this
galaxy. We then made a prediction for the SED of another typical star-forming
dwarf, I Zw 18. We also presented the evolution of the SED of LBGs. Finally, we
discussed the possibility of observing forming galaxies at z > 5.


title:
Estimate of the total kinetic power and age of extragalactic jet by its
  cocoon dynamics: The case of Cygnus A

abstract:
  We examine the constraints imposed on the total kinetic power ($L_{\rm j}$)
and the age ($t_{\rm age}$) of relativistic jets in FR II radio sources in a
new way. We solve the dynamical expansion of its cocoon embedded in the
intra-cluster medium (ICM) and obtain the analytic solution of its physical
quantities in terms of $L_{\rm j}$ and $t_{\rm age}$. The estimate of $L_{\rm
j}$ and $t_{\rm age}$ is done by the comparison of the model and the observed
shape of the cocoon. The analysis is focused on Cygnus A and we find that (i)
the source age is $3 {\rm Myr} <t_{\rm age}<30 {\rm Myr}$ and (ii) the total
kinetic power of the jet is estimated as $0.2\times 10^{46}{\rm erg s^{-1}}
<L_{\rm j}<1\times 10^{48} {\rm erg s^{-1}}$ which is larger than 1% of the
Eddington luminosity of Cygnus A.


title: Bars and Cold Dark Matter Halos

abstract:
  The central part of a dark matter halo reacts to the presence and evolution
of a bar. Not only does the halo absorb angular momentum from the disk, it can
also be compressed and have its shape modified. We study these issues in a
series of cosmologically motivated, highly resolved N-body simulations of
barred galaxies run under different initial conditions. In all models we find
that the inner halo's central density increases. We model this density increase
using the standard adiabatic approximation and the modified formula by Gnedin
et al. and find that halo mass profiles are better reproduced by this latter.
In models with a strong bar, the dark matter in the central region forms a
bar-like structure (``dark matter bar''), which rotates together with the
normal bar formed by the stellar component (``stellar bar''). The
minor-to-major axial ratio of a halo bar changes with radius with a typical
value 0.7 in the central disk region. DM bar amplitude is mostly a function of
the stellar bar strength. Models in which the bar amplitude increases or stays
roughly constant with time, initially large (40%-60%) misalignment between the
halo and disk bars quickly decreases with time as the bar grows. The halo bar
is nearly aligned with the stellar bar (~10 degrees lag for the halo) after ~2
Gyr. The torque, which the halo bar exerts on the stellar bar, can serve as a
mechanism to regulate the angular momentum transfer from the disk to the halo.


title: X-ray and Near-infrared Studies of a Star-forming Cloud; L1448

abstract:
  We present the results of X-ray and near-infrared (NIR) observations of
L1448, a star-forming region in the Perseus cloud complex using the Chandra
X-ray Observatory and the 4 m telescope at the Kitt Peak National Observatory.
We detect 72 X-ray sources in a ~17 arcmin x 17 arcmin region with a ~68 ks
ACIS exposure, for which we conduct follow-up NIR imaging observations in a
concentric ~11 arcmin x 11 arcmin region with FLAMINGOS down to m_Ks ~ 17 mag.
Twelve X-ray sources have NIR or optical counterparts. By plotting X-ray mean
energy versus NIR to X-ray flux ratio, the X-ray sources are clearly separated
into two groups. The X-ray spectral and temporal features as well as NIR
magnitudes and colors indicate that one group mainly consists of young stellar
objects (YSOs) in the cloud and the other of background extragalactic sources.
Ten X-ray-emitting YSO candidates are thus newly identified, which are low-mass
or brown dwarf mass sources from their NIR magnitudes. In addition, a possible
X-ray signal is found from a mid-infrared protostar L1448 IRS 3(A). The lack of
detection of this source in our deep NIR images indicates that this source has
a very steep spectral slope of > 3.2 in 2--10 micron.


title: The anatomy of a quadruply imaged gravitational lens system

abstract:
  The key to using a strong gravitational lens system to measure the Hubble
constant is to obtain an accurate model of the lens potential. In this paper,
we investigate the properties of gravitational lens B1608+656, a
quadruply-imaged lens system with an extended source intensity distribution.
Our analysis is valid for generic quadruply-lensed systems. Limit curves and
isophotal separatrices are defined for such systems, and we show that the
isophotal separatrices must intersect at the critical curves and the satellite
isophotes must be tangent to the limit curves. The current model of B1608+656
(Koopmans et al. 2003) satisfies these criteria for some, but not all, of the
isophotal separatrices within the observational uncertainty. We study a
non-parametric method of potential reconstruction proposed by Blandford, Surpi
& Kundic (2001) and demonstrate that although the method works in principle and
elucidates image formation, the initial potential only converges to the true
model when it is within ~ 1 percent of the true model.


title: Optical and Near-Infrared spectroscopy of Nova V1494 Aquilae 1999 #2

abstract:
  Optical and near-infrared spectroscopic observations of the fast nova V1494
Aquilae 1999 #2 covering various phases -- early decline, transition and
nebular -- during the first eighteen months of its post-outburst evolution are
presented in this paper. During this period, the nova evolved in the P_fe
P_fe^o C_o spectral sequence. The transition from an optically thick wind to a
polar blob - equatorial ring geometry is seen in the evolution of the spectral
line profiles. There is evidence of density and temperature stratification in
the ejecta. Physical conditions in the ejecta have been estimated based on our
observations.


title:
SDSS J0246-0825: A New Gravitationally Lensed Quasar from the Sloan
  Digital Sky Survey

abstract:
  We report the discovery of a new two-image gravitationally lensed quasar,
SDSS J024634.11-082536.2 (SDSS J0246-0825). This object was selected as a
lensed quasar candidate from the Sloan Digital Sky Survey (SDSS) by the same
algorithm that was used to discover other SDSS lensed quasars (e.g., SDSS
J0924+0219). Multicolor imaging with the Magellan Consortium's Walter Baade
6.5-m telescope and the spectroscopic observations using the W. M. Keck
Observatory's Keck II telescope confirm that SDSS J0246-0825 consists of two
lensed images ($\Delta{\theta}=$1\farcs04) of a source quasar at z=1.68.
Imaging observations with the Keck telescope and the Hubble Space Telescope
reveal an extended object between the two quasar components, which is likely to
be a lensing galaxy of this system. From the absorption lines in the spectra of
quasar components and the apparent magnitude of the galaxy, combined with the
expected absolute magnitude from the Faber-Jackson relation, we estimate the
redshift of the lensing galaxy to be z=0.724. A highly distorted ring is
visible in the Hubble Space Telescope images, which is likely to be the lensed
host galaxy of the source quasar. Simple mass modeling predicts the possibility
that there is a small (faint) lensing object near the primary lensing galaxy.


title:
Spectral Evolution of a Luminous Compact X-Ray Source in NGC 253 with
  Chandra and XMM-Newton

abstract:
  Spectral studies of a luminous X-ray source, NGC 253 X21, are presented based
on archival Chandra and XMM-Newton data. The Chandra observation on 1999
December 16 detected the source at a bolometric luminosity of 0.3 x 10^39 erg/s
(assuming isotropic emission), while an XMM-Newton observation on 2000 June 3
revealed a short-term source variation in the range of (0.6--1.3) x 10^39
erg/s. All spectra from these observations were successfully modeled by
emission from an optically thick accretion disk. The average inner disk radius
was kept constant at 63 x (cos 60/cos i)^(1/2) km, where i is the disk
inclination, and did not vary significantly, while the disk inner temperature
changed in the range of 0.9--1.4 keV. Assuming that this object is an accreting
Schwarzschild black hole, and that the disk inner radius coincides with its
last stable orbit, the mass of the black hole is estimated to be ~ 7 M_sun. The
disk luminosity corresponds to (30--120) x (cos 60/cos i) % of the Eddington
limit of this black hole. Therefore, this luminous X-ray source, NGC 253 X21,
is understood consistently to be an accreting stellar mass black hole in the
standard disk state.


title:
A Catalogue of Field Horizontal Branch Stars Aligned with High Velocity
  Clouds

abstract:
  We present a catalogue of 430 Field Horizontal Branch (FHB) stars, selected
from the Hamburg/ESO Survey (HES), which fortuitously align with high column
density neutral hydrogen (HI) High-Velocity Cloud (HVC) gas. These stars are
ideal candidates for absorption-line studies of HVCs, attempts at which have
been made for almost 40 years with little success. A parent sample of 8321 HES
FHB stars was used to extract HI spectra along each line-of-sight, using the HI
Parkes All-Sky Survey. All lines-of-sight aligned with high velocity HI
emission with peak brightness temperatures greater than 120mK were examined.
The HI spectra of these 430 probes were visually screened and cross-referenced
with several HVC catalogues. In a forthcoming paper, we report on the results
of high-resolution spectroscopic observations of a sample of stars drawn from
this catalogue.


title:
Confirmation of two extended objects along the line of sight to
  PKS1830-211 with ESO-VLT adaptive optics imaging

abstract:
  We report on new high-resolution near-infrared images of the gravitationally
lensed radio source PKS1830-211, a quasar at z=2.507. These adaptive optics
observations, taken with the Very Large Telescope (VLT), are further improved
through image deconvolution. They confirm the presence of a second object along
the line of sight to the quasar, in addition to the previously known spiral
galaxy. This additional object is clearly extended in our images. However, its
faint luminosity does not allow to infer any photometric redshift. If this
galaxy is located in the foreground of PKS1830-211, it complicates the modeling
of this system and decreases the interest in using PKS1830-211 as a means to
determine H0 via the time delay between the two lensed images of the quasar.


title:
The Millennium Galaxy Catalogue: Dynamically Close Galaxy Pairs and the
  Global Merger Rate

abstract:
  We derive the number of dynamically close companions per galaxy ($N_c$) and
their total luminosity ($L_c$) for galaxies in the Millennium Galaxy Catalogue:
$N_c$ is similar to the fraction of galaxies in close pairs and is directly
related to the galaxy merger rate. We find $N_c=0.0174 \pm 0.0015$ and
$L_c=(252 \pm 30) \times 10^6$ $L_{\odot}$ for galaxies with $-22 < M_B -5 \log
h < -19$ with $<z>=0.123$ and $N_c=0.0357 \pm 0.0027$, $L_c= (294 \pm 31)
\times 10^6 L_{\odot}$ for galaxies with $-21 < M_B -5 \log h < -18$, with
$<z>=0.116$. The integrated merger rate to $z=1$ for both samples is about 20
%, but this depends sensitively on the fraction of kinematic pairs that are
truly undergoing a merger (assumed here to be 50%), the evolution of the merger
rate (here as $(1+z)^3$) and the adopted timescale for mergers (0.2 and 0.5 Gyr
for each sample, respectively). Galaxies involved in mergers tend to be
marginally bluer than non-interacting galaxies and show an excess of both
early-type and very late-type objects and a deficiency of intermediate-type
spirals. This suggests that interactions and mergers partly drive the star
formation and morphological evolution of galaxies.


title:
Which physical parameters can be inferred from the emission variability
  of relativistic jets?

abstract:
  We present results of a detailed numerical study and theoretical analysis of
the dynamics of internal shocks in relativistic jets and the non-thermal flares
associated with these shocks. In our model internal shocks result from
collisions of density inhomogeneities (shells) in relativistic jet flows. We
find that the merged shell resulting from the inelastic collision of shells has
a complicated internal structure due to the non-linear dynamics of the
interaction. Furthermore, the instantaneous efficiency for converting kinetic
energy into thermal energy is found to be almost twice as high as theoretically
expected during the period of significant emission. The Lorentz factors of the
internal shocks are correlated with the initial inertial masses of the shells.
  Because of the complexity of the non-linear evolution the merged shell
becomes very inhomogeneous and simple one-zone models are inadequate to extract
physical parameters of the emitting region from the resulting light curves. In
order to improve on these one-zone approximations, we propose a novel way of
analyzing the space-time properties of the emission. Based on these properties
we construct an analytic model of non-thermal flares which can be used to
constrain some (unobservable) physical parameters of the internal shocks. These
are the ratio of the Lorentz factors between the forward and the reverse shock
(caused by the shell collision), and the shell crossing times of these shocks.
The analytic model is validated by applying it to the synthetic light curves
computed from our models. It can equally well be applied to observations.


title: The Diffuse Nature of Stromgren Spheres

abstract:
  In this Letter, we argue that the standard analytical derivations of
properties of HII regions, such as the speed, shape and asymptotic position of
ionisation fronts require a more precise treatment. These derivations use the
on the spot approximation, which in effect ignores the diffuse component of the
radiation field. We show that, in fact, HII regions are diffusion dominated.
This has as a result that the morphology of inhomogeneous HII regions will be
drastically different, because shadowing effects have a less profound impact on
the apparent shape. Moreover, it will have influence on the propagation speed
of ionisation fronts. We quantify our claims by analytically deriving the
internal radiation structure of HII regions, taking diffusion fully into
account for several different cosmologically relevant density distributions.


title:
New distances of unresolved dwarf elliptical galaxies in the vicinity of
  the Local Group

abstract:
  We present Surface Brightness Fluctuation distances of nine early-type dwarf
galaxies and the S0 galaxy NGC 4150 in the Local Volume based on deep B- and
R-band CCD images obtained with the 2.56 metre Nordic Optical Telescope.
Typically, six stellar fields at various galactocentric distances have been
chosen for each galaxy as appropriately free of foreground stars and other
contaminants, and Fourier analysed to determine the distances, which are found
to lie in the range of 3 to 16 Mpc. The SBF method is thus demonstrated to
efficiently measure distances from the ground with mid-aperture telescopes for
galaxies for which only the tip of the red giant branch method in combination
with the Hubble Space Telescope has been available until now. We obtained the
following distance moduli: 28.11 +/- 0.15 mag (or 4.2 +/- 0.3 Mpc) for UGC
1703, 27.61 +/- 0.17 mag (or 3.3 +/- 0.3 Mpc) for KDG 61, 29.00 +/- 0.27 mag
(or 6.3 +/- 0.8 Mpc) for UGCA 200, 27.74 +/- 0.18 mag (or 3.5 +/- 0.3 Mpc) for
UGC 5442, 30.22 +/- 0.17 mag (or 11.1 +/- 0.9 Mpc) for UGC 5944, 30.79 +/- 0.11
mag (or 14.4 +/- 0.7 Mpc) for NGC 4150, 31.02 +/- 0.25 mag (or 16.0 +/- 1.9
Mpc) for BTS 128, 29.27 +/- 0.16 mag (or 7.1 +/- 0.6 Mpc) for UGC 7639, 30.19
+/- 0.23 mag (or 10.9 +/- 1.2 Mpc) for UGC 8799 with an alternative distance of
30.61 +/- 0.26 mag (or 13.2 +/- 1.7 Mpc), and 29.60 +/- 0.20 mag (or 8.3 +/-
0.8 Mpc) for UGC 8882.


title:
Making the corona and the fast solar wind: a self-consistent simulation
  for the low-frequency Alfven waves from photosphere to 0.3AU

abstract:
  We show that the coronal heating and the fast solar wind acceleration in the
coronal holes are natural consequence of the footpoint fluctuations of the
magnetic fields at the photosphere, by performing one-dimensional
magnetohydrodynamical simulation with radiative cooling and thermal conduction.
We initially set up a static open flux tube with temperature 10^4K rooted at
the photosphere. We impose transverse photospheric motions corresponding to the
granulations with velocity <dv> = 0.7km/s and period between 20 seconds and 30
minutes, which generate outgoing Alfven waves. We self-consistently treat these
waves and the plasma heating. After attenuation in the chromosphere by ~85% of
the initial energy flux, the outgoing Alfven waves enter the corona and
contribute to the heating and acceleration of the plasma mainly by the
nonlinear generation of the compressive waves and shocks. Our result clearly
shows that the initial cool and static atmosphere is naturally heated up to
10^6K and accelerated to 800km/s.


title:
An asteroseismic study of the Beta Cephei star Theta Ophiuchi:
  photometric results

abstract:
  We have carried out a three-site photometric campaign for the Beta Cephei
star Theta Ophiuchi from April to August 2003. 245 hours of differential
photoelectric uvy photometry were obtained during 77 clear nights. The
frequency analysis of our measurements resulted in the detection of seven
pulsation modes within a narrow frequency interval between 7.116 and 7.973 c/d.
No combination or harmonic frequencies were found. We performed a mode
identification of the individual pulsations from our colour photometry that
shows the presence of one radial mode, one rotationally split l=1 triplet and
possibly three components of a rotationally split l=2 quintuplet. We discuss
the implications of our findings and point out the similarity of the pulsation
spectrum of Theta Ophiuchi to that of another Beta Cephei star, V836 Cen.


title: Proper orthogonal decomposition of solar photospheric motions

abstract:
  The spatio-temporal dynamics of the solar photosphere is studied by
performing a Proper Orthogonal Decomposition (POD) of line of sight velocity
fields computed from high resolution data coming from the MDI/SOHO instrument.
Using this technique, we are able to identify and characterize the different
dynamical regimes acting in the system. Low frequency oscillations, with
frequencies in the range 20-130 microHz, dominate the most energetic POD modes
(excluding solar rotation), and are characterized by spatial patterns with
typical scales of about 3 Mm. Patterns with larger typical scales of 10 Mm, are
associated to p-modes oscillations at frequencies of about 3000 microHz.


title: Tangled magnetic fields and CMBR signal from reionization epoch

abstract:
  We compute the secondary CMBR anisotropy signal from the reionization of the
universe in the presence of tangled magnetic fields. We consider the tangled
magnetic-field-induced scalar, vector, and tensor modes for our analysis. The
most interesting signal for l<10 arise from tensor perturbations. In
particular, we show that the enhancement observed by WMAP in the TE
cross-correlation signal for l<10 could be explained by tensor TE
cross-correlation from tangled magnetic fields generated during the
inflationary epoch for magnetic field strength B_0=4.5*10^{-9}G and magnetic
field power spectrum spectral index n=-2.9. Alternatively, a mixture of tensor
mode signal with primordial scalar modes give weaker bounds on the value of the
optical depth to the reionization surface, tau_{reion}=0.11 +/- 0.02. This
analysis can also be translated to a limit on the magnetic field strength of
nearly 5*10{-9}G for wave-numbers < 0.05 Mpc^{-1}


title:
An asteroseismic study of the Beta Cephei star Theta Ophiuchi:
  spectroscopic results

abstract:
  We present the results of a detailed analysis of 121 ground-based
high-resolution high S/N spectroscopic measurements spread over 3 years for the
Beta Cephei star Theta Ophiuchi. We discovered Theta Oph to be a triple system.
In addition to the already known Speckle B5 companion of the B2 primary, we
showed the presence of a low-mass spectroscopic companion and we derived an
orbital period of 56.71 days with an eccentricity of 0.1670. After removing the
orbit we determined two frequencies for the primary in the residual radial
velocities: f1 = 7.1160 c/d and f2 = 7.4676 c/d. We also found the presence of
f3 = 7.3696 c/d by means of a two dimensional frequency search across the Si
III 4567 A profiles. We identified the m-value of the main mode with frequency
f1 by taking into account the photometric identifications of the degrees l. By
means of the moment method and the amplitude and phase variations across the
line profile, we derived (l1,m1) = (2,-1). This result allows us to fix the
mode identifications of the whole quintuplet for which three components were
detected in photometry. This is of particular use for our forthcoming seismic
modelling of the primary. We also determined stellar parameters of the primary
by non-local thermodynamic equilibrium hydrogen, helium and silicon line
profile fitting and we obtained Teff = 24000 K and log g = 4.1, which is
consistent with photometrically determined values.


title:
Towards Planetesimals in the Disk around TW Hya: 3.5 centimeter Dust
  Emission

abstract:
  We present Very Large Array observations at 3.5 cm of the nearby young star
TW Hya that show the emission is constant in time over weeks, months and years,
and spatially resolved with peak brightness temperature ~10 K at ~0.25 (15 AU)
resolution. These features are naturally explained if the emission mechanism at
this wavelength is thermal emission from dust particles in the disk surrounding
the star. To account quantitatively for the observations, we construct a
self-consistent accretion disk model that incorporates a population of
centimeter size particles that matches the long wavelength spectrum and spatial
distribution. A substantial mass fraction of orbiting particles in the TW Hya
disk must have agglomerated to centimeter size. These data provide the first
clear indication that dust emission from protoplanetary disks may be observed
at centimeter wavelengths, and that changes in the spectral slope of the dust
emission may be detected, providing constraints on dust evolution and the
planet formation process.


title:
The dynamics and high-energy emission of conductive gas clouds in
  supernova-driven galactic superwinds

abstract:
  In this paper we present high-resolution hydrodynamical models of warm
ionized clouds embedded in a superwind, and compare the OVI and soft X-ray
properties to the existing observational data. These models include thermal
conduction, which we show plays an important role in shaping both the dynamics
and radiative properties of the resulting wind/cloud interaction. Heat
conduction stabilizes the cloud by inhibiting the growth of K-H and R-T
instabilities, and also generates a shock wave at the cloud's surface that
compresses the cloud. This dynamical behaviour influences the observable
properties. We find that while OVI emission and absorption always arises in
cloud material at the periphery of the cloud, most of the soft X-ray arises in
the region between the wind bow shock and the cloud surface, and probes either
wind or cloud material depending on the strength of conduction and the relative
abundances of the wind with respect to the cloud. In general only a small
fraction (<1%) of the wind mechanical energy intersecting a cloud is radiated
away at UV and X-ray wavelengths, with more wind energy going into accelerating
the cloud. Models with heat conduction at Spitzer-levels are found to produce
observational properties closer to those observed in superwinds than models
with no thermal conduction, in particular in terms of the OVI-to-X-ray
luminosity ratio, but cloud life times are uncomfortably short (<1Myr) compared
to the dynamical ages of real winds. We experimented with reducing the thermal
conductivity and found that even when we reduced conduction by a factor of 25
that the simulations retained the beneficial hydrodynamical stability and low
O{\sc vi}-to-X-ray luminosity ratio found in the Spitzer-level conductive
models, while also having reduced evaporation rates.


title:
Time-resolved FUSE Photometric and Spectroscopic Observations:
  PG1219+534, PG1605+072, and PG1613+426

abstract:
  We report on the detection of pulsations in the far ultraviolet (hereafter
FUV) light curves of PG1219+534, PG1605+072, and PG1613+426 obtained with the
Far Ultraviolet Spectroscopic Explorer (FUSE) in time-tagged mode (TTAG).
Exposures of the order of a few Ksecs were sufficient to observe the main
frequencies of PG1219+534 and PG1605+072 and confirm the detection of a
pulsation mode at the surface of PG1613+426 as reported from ground. For the
first time we derive time-resolved spectroscopic FUSE data of a sdB pulsator
(PG1605+072) and comment its line profile variation diagram (hereafter lpv
diagram). We observe the phase shift between the maximum luminosity and the
maximum radius to be consistent with the model of an adiabatic pulsator. We
also present evidence that the line broadening previously reported is not
caused by rotation but is rather an observational bias due to the rapid Doppler
shift of the lines with 17 km.s-1 amplitude. Thus our observations do not
support the previous claim that PG1605+072 is (or will evolve into) an
unusually fast rotating degenerate dwarf. These results demonstrate the
asteroseismological potential of the FUSE satellite which should be viewed as
another powerful means of investigation of stellar pulsations along with the
MOST and COROT missions.


title:
Pair winds in Schwarzschild space-time with application to hot bare
  strange stars

abstract:
  We consider a time dependent, spherically outflowing wind, in Schwarzschild
space-time, consisting of electron-positron pairs and photons . Without
assuming thermal equilibrium, we account for the microphysics, including
two-body processes and their radiative three-body variants. We present a
finite-difference scheme for solving the general relativistic kinetic Boltzmann
equations for electron-positron pairs and photons. We apply this to the
concrete example of a wind from a hot, bare, strange star, predicted to be a
powerful source of hard X-ray photons and pairs created by the Coulomb barrier
at the quark surface. We study the kinetics of the wind particles and the
emerging emission in photons and pairs for stationary winds with total
luminosities in the range 10^{34}-10^{39} ergs/s, for different values of the
injected photon-to-pair ratio. The wind parameters--such as the mean optical
depth for photons, the rates of particle number and energy outflows, bulk
velocity, and number density of the pair plasma--are presented as functions of
the distance from the stellar surface, as well as characteristics of the
emergent radiation. We find that photons dominate in the emerging emission, and
the emerging photon spectrum is rather hard and differs substantially from the
thermal spectrum expected from a neutron star with the same luminosity. This
might help distinguish the putative bare strange stars from neutron stars.


title: Attenuation of acoustic waves in glacial ice and salt domes

abstract:
  Two classes of natural solid media (glacial ice and salt domes) are under
consideration as media in which to deploy instruments for detection of
neutrinos with energy >1e18 eV. Though insensitive to 1e11 to 1e16 eV neutrinos
for which observatories (e.g., AMANDA and IceCube) that utilize optical
Cherenkov radiation detectors are designed, radio and acoustic methods are
suited for searches for the very low fluxes of neutrinos with energies >1017
eV. This is because, due to the very long attenuation lengths of radio and
acoustic waves in ice and salt, detection modules can be spaced very far apart.
In this paper, I calculate the absorption and scattering coefficients as a
function of frequency and grain size for acoustic waves in glacial ice and salt
domes and show that experimental measurements on laboratory samples and in
glacial ice and salt domes are consistent with theory. For South Pole ice with
grain size 0.2 cm at -51 degrees C, scattering lengths are calculated to be
2000 km and 25 km at 10 kHz and 30 kHz, respectively, and the absorption length
is calculated to be 9 km at frequencies above 100 Hz. For NaCl (rock salt) with
grain size 0.75 cm, scattering lengths are calculated to be 120 km and 1.4 km
at 10 kHz and 30 kHz, and absorption lengths are calculated to be 30,000 km and
3300 km at 10 kHz and 30 kHz. Existing measurements are consistent with theory.
For ice, absorption is the limiting factor; for salt, scattering is the
limiting factor.


title:
Detection of a hot core in the intermediate-mass (IM) Class 0 protostar
  NGC 7129--FIRS2

abstract:
  We report high angular resolution (~0.6''x0.5'' at 1.3mm) observations of the
Class 0 intermediate-mass (IM) protostar NGC 7129--FIRS 2 using the PdBI. Our
observations show the existence of a hot core at the position of the Class 0
object. This is, up to our knowledge, the first IM hot core detected so far.
Interferometric maps of the region in the the continuum at 3mm and 1.3mm and in
the CH3CN 5_k-->4_k, CH3OH 5_kk'-->4_kk', and D2CO 4_04-->3_03 lines are
presented in this paper. Enhanced CH3CN and CH3OH abundances are measured
towards the hot core (X(CH3CN)~7.010^{-9}, X(CH3OH)~3 10^{-8}-- a few 10^{-7}).
While intense D2CO emission is detected towards the hot core, the N2D+ line has
not been detected in our interferometric observations. The different behaviors
of D2CO and N2D+ emissions suggest different formation mechanisms for the two
species and different deuteration processes for H2CO and N2H+ (surface and
gas-phase chemistry, respectively). Finally, the spectrum of the large
bandwidth correlator show a forest of lines at the hot core position revealing
that this object is extraordinarily rich in complex molecules.