title:
Relativistic cross sections of mass stripping and tidal disruption of a
  star by a super-massive rotating black hole

abstract:
  [abbreviated] We consider the problem of tidal disruption of a star by a
super-massive Kerr black hole. Using a numerically fast Lagrangian model of the
tidally disrupted star we survey the parameter space of the problem and find
the regions in the parameter space where the total disruption of the star or a
partial mass loss take place as a result of fly-by around the black hole. Our
treatment is based on General Relativity, and we consider the range of the
black hole masses where the tidal disruption competes with the relativistic
effect of direct capture of the star by the black hole. We find that our
results can be represented on the plane of specific orbital angular momenta of
the star $(j_{\theta}, j_{\phi})$. We calculate the contours of a given mass
loss of the star on this plane, referred to as the tidal cross sections, for a
given black hole mass $M$, rotational parameter $a$ and inclination of the
trajectory of the star with respect to the black hole equatorial plane. It is
shown that the tidal cross sections can be approximated as circles symmetric
above the axis $j_{\phi}=0$, and shifted with respect to the origin of the
coordinates in direction of negative $j_{\theta}$. The radii and shifts of
these circles are obtained numerically for the black hole masses in the range
$5\cdot 10^{5}M_{\odot}-10^{9}M_{\odot}$ and different values of $a$. It is
shown that when $a=0$ the tidal disruption takes place for $M < 5\cdot
10^{7}M_{\odot}$ and when $a\approx 1$ the tidal disruption is possible for $M
< 10^{9}M_{\odot}$.


title:
Cool Customers in the Stellar Graveyard III: Limits to Substellar
  Objects around nearby White Dwarfs using CFHT

abstract:
  Results from a groundbased high contrast imaging survey of thirteen nearby
white dwarfs for substellar objects is presented. We place strict upper limits
on the type of substellar objects present, ruling out the presence of anything
larger than $\sim$14 M$_{Jup}$ for eight of the white dwarfs at separations
$>$19 AU and corresponding to primordial separations of $\sim$3-6~AU assuming
adiabatic mass loss without tidal interactions.
  With these results we place the first upper limit on the number of
intermediate mass stars with brown dwarfs at separations $>$ 13 AU. We combine
these results with previous work to place upper limits on the number of massive
Jovian ($>$ 10 M$_{Jup}$) planets in orbit around white dwarfs whose
progenitors spanned a mass range of 1-7 M$_{\odot}$.


title:
PHASES Differential Astrometry and the Mutual Inclination of the V819
  Herculis Triple Star System

abstract:
  V819 Herculis is a well-studied triple star system consisting of a ``wide''
pair with 5.5 year period, one component of which is a 2.2-day period eclipsing
single-line spectroscopic binary. Differential astrometry measurements from the
Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) are
presented and used to determine a relative inclination between the short- and
long-period orbits of 23.6 +- 4.9 degrees. This represents only the sixth
unambiguous determination of the mutual inclination of orbits in a hierarchical
triple system. This result is combined with those for the other five systems
for analysis of the observed distribution of mutual inclinations in nearby
triple systems. It is found that this distribution is different than that which
one would expect from random orientations with statistical significance at the
94% level; implications for studying the spatial distribution of angular
momentum in star forming regions is discussed.


title: Statistics of Physical Properties of Dark Matter Clusters

abstract:
  We have identified over 2000 well resolved cluster halos, and also their
associated bound subhalos, from the output of a 1024^3 particle cosmological
N-body simulation (of box size 320 h^-1 Mpc and softening length 3.2 h^-1 kpc).
This has allowed us to measure halo quantities in a statistically meaningful
way, and for the first time analyse their distribution for a large and well
resolved sample. We characterize each halo in terms of its morphology,
concentration, spin, circular velocity and the fraction of their mass in
substructure. We also identify those halos that have not yet reached a state of
dynamical equilibrium using the virial theorem with an additional correction to
account for the surface pressure at the boundary. These amount to 3.4% of our
initial sample. For the virialized halos, we find a median of 5.6% of halo mass
is contained within substructure, with the distribution ranging between no
identified subhalos to 65%. The fraction of mass in substructure increases with
halo mass with logarithmic slope of 0.44 +- 0.06. Halos tend to have a prolate
morphology, becoming more so with increasing mass. Subhalos have a greater
orbital angular momentum per unit mass than their host halo. Furthermore, their
orbital angular momentum is typically well aligned with that of their host.
Overall, we find that dimensionless properties of dark matter halos do depend
on their mass, thereby demonstrating a lack of self-similarity.


title:
The Case for Anisotropic Afterglow Efficiency within Gamma-Ray Burst
  Jets

abstract:
  Early X-ray afterglows recently detected by {\it Swift} frequently show a
phase of very shallow flux decay lasting from $\sim 10^{2.5} $s up to $\sim
10^4 $s, followed by a steeper, more familiar decay. We suggest that the flat
early part of the light curve may be a combination of the decaying tail of the
prompt emission and the delayed onset of the afterglow emission observed from
viewing angles slightly outside the edge of the region within the jet with
prominent afterglow emission, as predicted previously. This would imply that a
significant fraction of viewers get very little external shock energy along
their line of sight, and, therefore, see a very high $\gamma$-ray to kinetic
energy ratio at early times. The early flat phase in the afterglow light curve
implies, in a rather robust and model independent manner, a very large
$\gamma$-ray efficiency, typically $\gtrsim 90%$, which is very difficult to
extract from baryons by internal shocks.


title: Shapes and Sizes of Voids in the LCDM Universe: Excursion Set Approach

abstract:
  We study the global distribution and morphology of dark matter voids in a
LCDM universe using density fields generated by N-body simulations. Voids are
defined as isolated regions of the low-density excursion set specified via
density thresholds, the density thresholds being quantified by the
corresponding filling factors, i.e., the fraction of the total volume in the
excursion set. Our work encompasses a systematic investigation of the void
volume function, the volume fraction in voids, and the fitting of voids to
corresponding ellipsoids and spheres. We emphasize the relevance of the
percolation threshold to the void volume statistics of the density field both
in the high redshift, Gaussian random field regime, as well as in the present
epoch. By using measures such as the Inverse Porosity, we characterize the
quality of ellipsoidal fits to voids, finding that such fits are a poor
representation of the larger voids that dominate the volume of the void
excursion set.


title:
The Detection of Crystalline Silicates in Ultra-Luminous Infrared
  Galaxies

abstract:
  Silicates are an important component of interstellar dust and the structure
of these grains -- amorphous versus crystalline -- is sensitive to the local
physical conditions. We have studied the infrared spectra of a sample of
ultra-luminous infrared galaxies. Here, we report the discovery of weak, narrow
absorption features at 11, 16, 19, 23, and 28 microns, characteristic of
crystalline silicates, superimposed on the broad absorption bands at 10 and 18
microns due to amorphous silicates in a subset of this sample. These features
betray the presence of forsterite (Mg_2SiO_4), the magnesium-rich end member of
the olivines. Previously, crystalline silicates have only been observed in
circumstellar environments. The derived fraction of forsterite to amorphous
silicates is typically 0.1 in these ULIRGs. This is much larger than the upper
limit for this ratio in the interstellar medium of the Milky Way, 0.01. These
results suggest that the timescale for injection of crystalline silicates into
the ISM is short in a merger-driven starburst environment (e.g., as compared to
the total time to dissipate the gas), pointing towards massive stars as a
prominent source of crystalline silicates. Furthermore, amorphization due to
cosmic rays, which is thought to be of prime importance for the local ISM, lags
in vigorous starburst environments.


title: The Swift/BAT High Latitude Survey: First Results

abstract:
  We present preliminary results from the first 3 months of the Swift BAT high
galactic latitude survey in the 14--195 keV band. The survey reaches a flux of
\~10^{-11} erg/cm^2/s and has ~2.7' (90% confidence) positional uncertainties
for the faintest sources. This represents the most sensitive survey to date in
this energy band. These data confirm the conjectures that a high energy
selected AGN sample would have very different properties from those selected in
other bands and represent a `true' sample of the AGN population. We have
identified 86% of the 66 high-latitude sources. 12 are galactic type sources
and 44 can be identified with previously known AGN. All but 5 of the AGN have
archival X-ray spectra, enabling the estimation of line of sight column
densities and other spectral properties. Both of the z > 0.11 objects are
Blazars. The median redshift of the others (excluding radio-loud objects) is
0.012. We find that the column density distribution of these AGN is bimodal
with 64% of the non-blazar sources having column densities N_H >= 10^{22}
cm$^{-2}$. None of the sources with log L_X > 43.5 show high column densities
and very few of the lower L_X sources have low column densities. Based on these
data, we expect the final BAT catalog to have >200 AGN and reach fluxes of less
than ~10^{-11} erg/cm^2/s over the entire sky.


title:
Infrared 3-4 Micron Spectroscopic Investigations of a Large Sample of
  Nearby Ultraluminous Infrared Galaxies

abstract:
  We present infrared L-band (3-4 micron) nuclear spectra of a large sample of
nearby ultraluminous infrared galaxies (ULIRGs).ULIRGs classified optically as
non-Seyferts (LINERs, HII-regions, and unclassified) are our main targets.
Using the 3.3 micron polycyclic aromatic hydrocarbon (PAH) emission and
absorption features at 3.1 micron due to ice-covered dust and at 3.4 micron
produced by bare carbonaceous dust, we search for signatures of powerful active
galactic nuclei (AGNs) deeply buried along virtually all lines-of-sight. The
3.3 micron PAH emission, the signatures of starbursts, is detected in all but
two non-Seyfert ULIRGs, but the estimated starburst magnitudes can account for
only a small fraction of the infrared luminosities. Three LINER ULIRGs show
spectra typical of almost pure buried AGNs, namely, strong absorption features
with very small equivalent-width PAH emission. Besides these three sources, 14
LINER and 3 HII ULIRGs' nuclei show strong absorption features whose absolute
optical depths suggest an energy source more centrally concentrated than the
surrounding dust, such as a buried AGN. In total, 17 out of 27 (63%) LINER and
3 out of 13 (23%) HII ULIRGs' nuclei show some degree of evidence for powerful
buried AGNs, suggesting that powerful buried AGNs may be more common in LINER
ULIRGs than in HII ULIRGs. The evidence of AGNs is found in non-Seyfert ULIRGs
with both warm and cool far-infrared colors. These spectra are compared with
those of 15 ULIRGs' nuclei with optical Seyfert signatures taken for
comparison.The overall spectral properties suggest that the total amount of
dust around buried AGNs in non-Seyfert ULIRGs is systematically larger than
that around AGNs in Seyfert 2 ULIRGs.


title:
Are Neutral Sunspot Winds Important for Penumbral Dynamics and the First
  Ionization Potential Effect?

abstract:
  The low ionization state in parts of a sunspot may play an important role in
its evolution and dynamical state. The cool magnetic interior region of the
sunspot develops a substantial neutral atomic and molecular hydrogen osmotic
pressure which can drive a wind outward from the umbra. Ambipolar diffusion
against the magnetically pinned ionized plasma component can also distort the
umbral magnetic field into a filamentary penumbral structure. This may be
important for explaining the development of the sunspot penumbra and the
Evershed flow. This fractionation process may also be important for the ``First
Ionization Potential'' (FIP) effect seen in the solar wind. In support of this
mechanism we find evidence for such ionization fractionization in UV
observations of molecular hydrogen in a sunspot umbra and penumbra.


title: Strong Gravitational Lens Inversion: A Bayesian Approach

abstract:
  If an extended source, such as a galaxy, is gravitationally lensed by a
massive object in the foreground, the lensing distorts the observed image. It
is straightforward to simulate what the observed image would be for a
particular lens and source combination. In practice, one observes the lensed
image on the sky, but blurred by atmospheric and telescopic effects and also
contaminated with noise. The question that then arises is, given this
incomplete data, what combinations of lens mass distribution and source surface
brightness profile could plausibly have produced this image? This is a classic
example of an inverse problem, and the method for solving it is given by the
framework of Bayesian inference. In this paper we demonstrate the application
of Bayesian inference to the problem of gravitational lens reconstruction, and
illustrate the use of Markov Chain Monte Carlo simulations which can be used
when the analytical calculations become too difficult. Previous methods for
performing gravitational lens inversion are seen in a new light, as special
cases of the general approach presented in this paper. Thus, we are able to
answer, at least in principle, lingering questions about the uncertainties in
the reconstructed source and lens parameters, taking into account all of the
data and any prior information we may have.


title: ELVIS - ELectromagnetic Vector Information Sensor

abstract:
  The ELVIS instrument was recently proposed by the authors for the Indian
Chandrayaan-1 mission to the Moon and is presently under consideration by the
Indian Space Research Organisation (ISRO). The scientific objective of ELVIS is
to explore the electromagnetic environment of the moon. ELVIS samples the full
three-dimensional (3D) electric field vector, E(x,t), up to 18 MHz, with
selective Nyqvist frequency bandwidths down to 5 kHz, and one component of the
magnetic field vector, B(x,t), from a few Hz up to 100 kHz.As a transient
detector, ELVIS is capable of detecting pulses with a minimum pulse width of 5
ns. The instrument comprises three orthogonal electric dipole antennas, one
magnetic search coil antenna and a four-channel digital sampling system,
utilising flexible digital down conversion and filtering together with
state-of-the-art onboard digital signal processing.


title:
Discovery of a Low Mass Bipolar Molecular Outflow from L1014-IRS with
  the Submillimeter Array

abstract:
  Using the Submillimeter Array we report the discovery of a compact low mass
bipolar molecular outflow from L1014-IRS and confirm its association with the
L1014 dense core at 200 pc. Consequently, L1014-IRS is the lowest luminosity (L
\~0.09 Lsun) and perhaps the lowest mass source known to be driving a bipolar
molecular outflow, which is one of the smallest known in size (~500 AU), mass
(< 10^{-4} Msun), and energetics (e.g., force < 10^{-7} Msun km/s/yr).


title:
Significant evolution of the stellar mass-metallicity relation since
  z~0.65

abstract:
  We present the stellar mass-metallicity relation for 34 0.4<z<1 galaxies
selected from CFRS and Marano fields, and compare it to those derived from
three local samples of galaxies (NFGS, KISS and SDSS). Our metal abundance
estimates account for extinction effects, as estimated from IR/optical ratios
and Balmer line ratios. All three comparisons show that the intermediate mass
galaxies at z~0.65 are more metal-deficient by 0.3 dex at a given M_K or
stellar mass relative to z=0. We find no evidence that this discrepancy could
be related to different methods used to derive mass and metallicity. Assuming a
closed box model predicts a gas fraction converted into stars of 20-25% since
z~0.65, if the gas fraction is 10-20% in present-day galaxies with intermediate
masses. This result is in excellent agreement with previous findings that most
of the decline of the cosmic star formation density is related to the
population of intermediate mass galaxies, which is composed of 75% spirals
today. We find no evidence for a change of the slope of the M_{\star}-Z
relation from z~0.65 to z=0 within the intermediate mass range
(10.5<log(M_{\star}) < 11.5).


title: Multiwavelength Observations of one Galaxy in Marano Field

abstract:
  We report the multiwavelength observations of one intermediate redshift
(z=0.3884) galaxy in the Marano Field. These data include ISOCAM middle
infrared, VLT/FORS2 spectroscopic and photometric data, associated with the
ATCA 1.4 GHz radio and ROSAT PSPC X-ray observations from literature. The
Spectral Energy Distribution obtained by VLT spectroscopy exhibits its
early-type galaxy property, while, in the same time, it has obvious [OIII]5007
emission line. The diagnostic diagram from the optical emission line ratios
shows its Seyfert galaxy property. Its infrared-radio relation follows the
correlation of sources detected at 15 \mu and radio. It has a high X-ray
luminosity of 1.26*10^{43} ergs/s, which is much higher than the general
elliptical galaxies s with the similar B band luminosity, and is about 2 orders
of magnitude higher than the derived value from the star forming tracer, the
FIR luminosity. This means that the X-ray sources of this galaxy are not
stellar components, but the AGN is the dominant component.


title:
Gravitational Collapse and Neutrino Emission of Population III Massive
  Stars

abstract:
  Pop III stars are the first stars in the universe. They do not contain metals
and their formation and evolution may be different from that of stars of later
generations. In fact, according to the theory of star formation, Pop III stars
might have very massive components ($\sim 100 - 10000M_\odot$). In this paper,
we compute the spherically symmetric gravitational collapse of these Pop III
massive stars. We solve the general relativistic hydrodynamics and neutrino
transfer equations simultaneously, treating neutrino reactions in detail.
Unlike supermassive stars ($\gtrsim 10^5 M_\odot$), the stars of concern in
this paper become opaque to neutrinos. The collapse is simulated until after an
apparent horizon is formed. We confirm that the neutrino transfer plays a
crucial role in the dynamics of gravitational collapse, and find also that the
$\beta$-equilibration leads to a somewhat unfamiliar evolution of electron
fraction. Contrary to the naive expectation, the neutrino spectrum does not
become harder for more massive stars. This is mainly because the neutrino
cooling is more efficient and the outer core is more massive as the stellar
mass increases. Here the outer core is the outer part of the iron core falling
supersonically. We also evaluate the flux of relic neutrino from Pop III
massive stars. As expected, the detection of these neutrinos is difficult for
the currently operating detectors. However, if ever observed, the spectrum will
enable us to obtain the information on the formation history of Pop III stars.
We investigate 18 models covering the mass range of $300 - 10^4 M_\odot$,
making this study the most detailed numerical exploration of spherical
gravitational collapse of Pop III massive stars. This will also serve as an
important foundation for multi-dimensional investigations.


title:
Infrared and radio study of star forming regions associated with IRAS
  19111+1048 and IRAS 19110+1045

abstract:
  A multiwavelength study of the star forming regions associated with IRAS
19111+1048 and IRAS 19110+1045 has been carried out. These have been
simultaneously mapped in two far infrared bands at lambda_eff ~ 130 and 200
micron with ~1' angular resolution using the TIFR 1-m balloon borne telescope.
The radio emission from the ionised gas of these regions has been imaged at
1280, 610 and 325 MHz using the Giant Metrewave Radio Telescope, India. A total
of 20 compact radio sources have been detected from the high resolution radio
map of IRAS 19111+1048 at 1280 MHz. Assuming these sources to represent
exciting zero age main sequence (ZAMS) stars, the initial mass function is
found to be quite steep, with the power law index of 5.3+-0.5 for the mass
range 14 < m/M_sun < 33. The spectral types of the ZAMS stars inferred
independently from the radio and NIR measurements match very well for a good
fraction of the radio sources having NIR counterparts. For IRAS 19110+1045
region, seven radio sources have been detected of which two are associated with
deeply embedded 2MASS objects. Self consistent radiative transfer modelling
aimed at extracting important physical and geometrical details of the two IRAS
sources has been carried out. A uniform density distribution of dust and gas is
implied for both the sources. The extents of ionised gas, number of ZAMS stars,
presence of deeply embedded sources and lower value of L/M for the cloud,
support the youth of IRAS 19110+1045 vis-a-vis its neighbour, IRAS 19111+1048,
consistent with earlier studies.


title:
On the origin of black hole X-ray emission in quiescence: Chandra
  observations of XTE J1550-564 and H 1743-322

abstract:
  We report the results of observations of the black hole binaries XTE
J1550-564 and H 1743-322 in their quiescent state using the Chandra X-ray
Observatory. Both sources are detected at their faintest level of X-ray
emission ever observed with a 0.5-10 keV unabsorbed luminosity of 2 $\times$
10$^{32}$ (d/5 kpc)$^2$ erg s$^{-1}$ for XTE J1550-564 and 9 $\times$ 10$^{31}$
(d/8 kpc)$^2$ erg s$^{-1}$ for H 1743-322. These luminosities are in the upper
range compared to the faintest levels observed in other black hole systems,
possibly related to residual accretion for these sources with frequent
outbursts. For XTE J1550-564, the Chandra observations also constrain the X-ray
spectrum as a fit with an absorbed power-law model yields a photon index of
2.25 $\pm$ 0.08, clearly indicating a softening of the X-ray spectrum at lower
luminosities compared to the standard hard state. Similar softening at low
luminosity is seen for several black hole transients with orbital periods less
than 60 hours. Most of the current models of accreting black holes are able to
reproduce such softening in quiescence. In contrast, we find that systems with
orbital periods longer than 60 hours appear to have hard spectra in quiescence
and their behaviour may be consistent with hardening in quiescence.


title: The formation of H_2 and HD with the master equation approach

abstract:
  The formation of H2 and HD molecules on interstellar dust grains is studied
using rate equation and master equation models. Rate equations are used in the
analysis of laboratory experiments which examine the formation of molecular
hydrogen on astrophysically relevant surfaces. However, under interstellar
conditions, rate equations are not suitable for the calculation of reaction
rates on dust-grain surfaces. Due to the low flux and the sub-micron size of
the grains, the populations of H and D atoms on a single grain are likely to be
small. In this case the reaction rates are dominated by fluctuations and should
be calculated using stochastic methods. The rate of molecular hydrogen
formation in interstellar clouds is evaluated using the master equation, taking
into account the distribution of grain sizes.


title: TeV Gamma-rays from the Northern Sky Pulsar Wind Nebulae

abstract:
  We estimate the TeV gamma-ray fluxes expected from the population of young
pulsars in terms of the self-consistent time dependent hadronic-leptonic model
for the high energy processes inside the pulsar wind nebulae. This radiation
model bases on the hypothesis of Arons and collaborators who postulate that
leptons are accelerated inside the nebulae as a result of resonant scattering
on heavy nuclei, which in turn are accelerated in the pulsar wind region or the
pulsar inner magnetosphere. Our aim is to find out which nebulae on the
nortehrn hemisphere are the best candidates for detection at energies above 60
GeV and 200 GeV by the next generation of low threshold Cherenkov telescopes.


title: The dependence of clustering on galaxy properties

abstract:
  (abridged)We use a sample of ~200,000 galaxies drawn from the Sloan Digital
Sky Survey to study how clustering depends on properties such as stellar mass
(M*), colour (g-r), 4000A break strength (D4000), concentration index (C), and
stellar surface mass density (\mu_*). We find that more massive galaxies
cluster more strongly than less massive galaxies, with the difference
increasing above the characteristic stellar mass of the Schechter mass
function. When divided by physical quantities, galaxies with redder colours,
larger D4000, higher C and larger \mu_* cluster more strongly. The clustering
differences are largest on small scales and for low mass galaxies. At fixed
stellar mass,the dependences of clustering on colour and 4000A break strength
are similar. Different results are obtained when galaxies are split by
concentration or surface density. The dependence of w(r_p) on g-r and D4000
extends out to physical scales that are significantly larger than those of
individual dark matter haloes (> 5 Mpc/h). This large-scale clustering
dependence is not seen for the parameters C or \mu_*. On small scales (< 1
Mpc/h), the amplitude of the correlation function is constant for ``young''
galaxies with 1.1 < D4000< 1.5 and a steeply rising function of age for
``older'' galaxies with D4000>1.5. In contrast, the dependence of the amplitude
of w(r_p) on concentration on scales less than 1 Mpc/h is strongest for
disk-dominated galaxies with C<2.6. This demonstrates that different processes
are required to explain environmental trends in the structure and in star
formation history of galaxies.


title: The dependence of the pairwise velocity dispersion on galaxy properties

abstract:
  (abridged) We present measurements of the pairwise velocity dispersion (PVD)
for different classes of galaxies in the Sloan Digital Sky Survey. For a sample
of about 200,000 galaxies, we study the dependence of the PVD on galaxy
properties such as luminosity, stellar mass (M_*), colour (g-r), 4000A break
strength (D4000), concentration index (C), and stellar surface mass density
(\mu_*). The luminosity dependence of the PVD is in good agreement with the
results of Jing & B\"orner (2004) for the 2dFGRS catalog. The value of
\sigma_{12} measured at k=1 h/Mpc decreases as a function of increasing galaxy
luminosity for galaxies fainter than L*, before increasing again for the most
luminous galaxies in our sample. Each of the galaxy subsamples selected
according to luminosity or stellar mass is divided into two further subsamples
according to colour, D4000, C and \mu_*. We find that galaxies with redder
colours and higher D4000, C, and \mu_* values have larger PVDs on all scales
and at all luminosities/stellar masses. The dependence of the PVD on parameters
related to recent star formation(colour, D4000) is stronger than on parameters
related to galaxy structure (C, \mu_*), especially on small scales and for
faint galaxies. The reddest galaxies and galaxies with high surface mass
densities and intermediate concentrations have the highest pairwise peculiar
velocities, i.e. these move in the strongest gravitational fields. We conclude
that the faint red population located in rich clusters is responsible for the
high PVD values that are measured for low-luminosity galaxies on small scales.


title:
New H-band Galaxy Number Counts: A Large Local Hole in the Galaxy
  Distribution?

abstract:
  We examine H-band number counts determined using new photometry over 0.30
sq.deg. to H=19, as well as H<14 counts from 2MASS. First, we examine 2MASS
counts extracted for the 4000 sq.deg. APM survey area and find a deficiency of
25% at H=13, in line with previous results. In addition the |b|>20 counts
display a relatively constant deficit in the counts of 15-20%. We investigate
various possible causes for these results: In order to address the issue of the
model normalisation, we examine faint number counts for the new faint
photometry presented in this work and also for the LCIRS. In each case a
zeropoint is chosen to match that of the 2MASS photometry at bright magnitudes.
We find a large offset between 2MASS and the LCIRS data of 0.28+/-0.01
magnitudes. Applying a consistent zeropoint, the combined faint data is in good
agreement with the homogeneous model prediction used previously. We examine
possible effects arising from unexpected galaxy evolution and photometric
errors and find no evidence for a significant contribution from either.
However, incompleteness in the 2MASS catalogue and in the faint data may have a
significant contribution. Addressing the contribution from large-scale
structure, we estimate the cosmic variance in the bright counts over the APM
survey area and for |b|>20 expected in a LCDM cosmology using 27 LCDM mock
2MASS catalogues. Accounting for the model normalisation uncertainty and taking
an upper limit for the incompleteness, the APM survey area bright counts are in
line with a rare fluctuation in the local galaxy distribution of 2.5 sigma.
However, the |b|>20 counts represent a 4.0 sigma fluctuation, and imply a local
hole which extends over the entire local galaxy distribution and is at odds
with LCDM.


title:
On the Velocity Field and the 3D Structure of the Galactic Soccer Ball
  Abell 43

abstract:
  Planetary nebulae (PNe) and their central stars (CSs) are ideal tools to test
evolutionary theory: photospheric properties of their exciting stars give
stringent constraints for theoretical predictions of stellar evolution. The
nebular abundances display the star's photosphere at the time of the nebula's
ejection which allows to look back into the history of stellar evolution - but,
more importantly, they even provide a possibility to investigate on the
chemical evolution of our Galaxy because most of the nuclear processed material
goes back into the interstellar medium via PNe.
  The recent developments in observation techniques and a new three-dimensional
photoionization code MOCASSIN enable us to analyze PNe properties precisely by
the construction of consistent models of PNe and CSs. In addition to PNe
imaging and spectroscopy, detailed information about the velocity field within
the PNe is a pre-requisite to employ de-projection techniques in modeling the
physical structureof the PNe.


title: Mixing zones in magnetized differentially rotating stars

abstract:
  We study the secular instability of magnetized differentially rotating
radiative zones taking account of viscosity and magnetic and thermal
diffusivities. The considered instability generalizes the well-known
Goldreich-Schubert-Fricke instability for the case of a sufficiently strong
magnetic field. In magnetized stars, instability can lead to a formation of
non-spherical unstable zones where weak turbulence mixes the material between
the surface and interiors. Such unstable zones can manifest themselves by a
non-spherical distribution of abundance anormalies on the stellar surface.


title: Small Scale Structure Formation in Chameleon Cosmology

abstract:
  Chameleon fields are scalar fields whose mass depends on the ambient matter
density. We investigate the effects of these fields on the growth of density
perturbations on sub-galactic scales and the formation of the first dark matter
halos. Density perturbations on comoving scales $R < 1 {\rm pc}$ go non--linear
and collapse to form structure much earlier than in standard $\Lambda$CDM
cosmology. The resulting mini-halos are hence more dense and resilient to
disruption. We therefore expect (provided that the density perturbations on
these scales have not been erased by damping processes) that the dark matter
distribution on small scales would be more clumpy in chameleon cosmology than
in the $\Lambda$CDM model.


title: Modeling the Optical Afterglow of GRB 030329

abstract:
  The best-sampled afterglow light curves are available for GRB 030329. A
distinguishing feature of this event is the obvious rebrightening at around 1.6
days after the burst. Proposed explanations for the rebrightening mainly
include the two-component jet model and the refreshed shock model, although a
sudden density-jump in the circumburst environment is also a potential choice.
Here we re-examine the optical afterglow of GRB 030329 numerically in light of
the three models. In the density-jump model, no obvious rebrightening can be
produced at the jump moment. Additionally, after the density jump, the
predicted flux density decreases rapidly to a level that is significantly below
observations. A simple density-jump model thus can be excluded. In the
two-component jet model, although the observed late afterglow (after 1.6 days)
can potentially be explained as emission from the wide-component, the emergence
of this emission actually is too slow and it does not manifest as a
rebrightening as previously expected. The energy-injection model seems to be
the most preferred choice. By engaging a sequence of energy-injection events,
it provides an acceptable fit to the rebrightening at $\sim 1.6$ d, as well as
the whole observed light curve that extends to $\sim 80$ d. Further studies on
these multiple energy-injection processes may provide a valuable insight into
the nature of the central engines of gamma-ray bursts.


title: Gravitational Wave Background from Magnetars

abstract:
  We investigate the gravitational wave background produced by magnetars. The
statistical properties of these highly magnetized stars were derived by
population synthesis methods and assumed to be also representative of
extragalactic objects. The adopted ellipticity was calculated from relativistic
models using equations of state and assumptions concerning the distribution of
currents in the neutron star interior. The maximum amplitude occurs around 1.2
kHz, corresponding to $\Omega_{gw} \sim 10^{-9}$ for a type I superconducting
neutron star model. The expected signal is a continuous background that could
mask the cosmological contribution produced in the early stage of the Universe.


title:
AGB stars in the Magellanic Clouds. II. The rate of star formation
  across the LMC

abstract:
  This article compares the distribution of Ks magnitude of Large Magellanic
Cloud (LMC) asymptotic giant branch (AGB) stars obtained from the DENIS and
2MASS data with theoretical distributions. These have been constructed using
up-to-date stellar evolution calculations for low and intermediate-mass stars,
and in particular for thermally pulsing AGB stars. A fit of both the magnitude
distribution of carbon- and oxygen-rich AGB stars allowed us to constrain the
metallicity distribution across the LMC and its star formation rate (SFR). The
LMC stellar population is found to be on average 5-6 Gyr old and is consistent
with a mean metallicity corresponding to Z=0.006. These values may however be
affected by systematic errors in the underlying stellar models, and by the
limited exploration of the possible SFR histories. Our method should be,
instead, particularly useful for detecting variations in the mean metallicity
and SFR across the LMC disk. In fact, there are well defined regions where both
the metallicity and the mean-age of the underlying stellar population span the
whole range of grid parameters. The C/M ratio discussed in paper I is a tracer
of the metallicity distribution if the underlying stellar population is older
than about a few Gyr. A similar study across the Small Magellanic Cloud is
given in paper III of this series.


title:
GaBoDS: The Garching-Bonn Deep Survey V. Data release of the ESO
  Deep-Public-Survey

abstract:
  Aims. In this paper the optical data of the ESO Deep-Public-Survey observed
with the Wide Field Imager and reduced with the THELI pipeline are described.
Methods. Here we present 63 fully reduced and stacked images. The astrometric
and photometric calibrations are discussed and the properties of the images are
compared to images released by the ESO Imaging Survey team covering a subset of
our data. Results. These images are publicly released to the community. Our
main scientific goals with this survey are to study the high-redshift universe
by optically pre-selecting high-redshift objects from imaging data and to use
VLT instruments for follow-up spectroscopy as well as weak lensing
applications.


title: Wavelets, ridgelets and curvelets on the sphere

abstract:
  We present in this paper new multiscale transforms on the sphere, namely the
isotropic undecimated wavelet transform, the pyramidal wavelet transform, the
ridgelet transform and the curvelet transform. All of these transforms can be
inverted i.e. we can exactly reconstruct the original data from its
coefficients in either representation. Several applications are described. We
show how these transforms can be used in denoising and especially in a Combined
Filtering Method, which uses both the wavelet and the curvelet transforms, thus
benefiting from the advantages of both transforms. An application to component
separation from multichannel data mapped to the sphere is also described in
which we take advantage of moving to a wavelet representation.


title: The luminosity function of the fossil group RX J1552.2+2013

abstract:
  We determine the first fossil group luminosity function based on spectroscopy
of the member galaxies. The fossil group RX J1552.2+2013 has 36 confirmed
members, it is at a mean redshift of 0.136 and has a velocity dispersion of 623
km/s (or 797 km/s if four emission lines galaxies in the outskirts of the
velocity distribution are included). The luminosity function of RX
J1552.2+2013, measured within the inner region of the system ~1/3 R_vir), in
the range -23.5< M_i'<-17.5, is well fitted by a Schechter function with
M*i'=-21.3 +/- 0.4 and alpha = -0.6 +/- 0.3 or a Gaussian function centered on
M_i'= -20.0 +/- 0.4 and with sigma=1.29 +/- 0.24 i' mag. (H_0 = 70 km/s Mpc,
Omega_M=0.3, Omega_Lambda=0.7. The luminosity function obtained from a
photometric survey in g', r', i'-bands (and statistical background correction)
confirms the spectroscopically determined results. There is a significant dip
in the luminosity function at M_r'=-18 mag, as also observed for other
clusters. RX~J1552.2+2013 is a rich, strongly red-galaxy dominated system, with
at least 19 galaxies with magnitudes between m_3 and m_3 + 2, within a surveyed
circular area of radius 625 kpc centered on the peak of the x-ray emission. Its
mass, ~3.0 10^14 M_0, M/L of 507 M_sol/L_B_sol and L_X of 6.3 10^43 ergs/s
(bolometric) are more representative of a fossil cluster than of a fossil
group. The central object of RX J1552.2+2013 is a cD galaxy which may have
accreted the more luminous ~L* former members of the group. Although dynamical
friction and subsequent merging are probably the processes responsible for the
lack of bright galaxies in the system, for the fainter members, there must be
another mechanism in action (perhaps tidal disruption) to deplete the fossil
group from intermediate-luminosity galaxies M_r' ~ -18.


title: Three-Body Dynamics with Gravitational Wave Emission

abstract:
  We present numerical three-body experiments that include the effects of
gravitational radiation reaction by using equations of motion that include the
2.5-order post-Newtonian force terms, which are the leading order terms of
energy loss from gravitational waves. We simulate binary-single interactions
and show that close approach cross sections for three 1 solar mass objects are
unchanged from the purely Newtonian dynamics except for close approaches
smaller than 1.0e-5 times the initial semimajor axis of the binary. We also
present cross sections for mergers resulting from gravitational radiation
during three-body encounters for a range of binary semimajor axes and mass
ratios including those of interest for intermediate-mass black holes (IMBHs).
Building on previous work, we simulate sequences of high-mass-ratio three-body
encounters that include the effects of gravitational radiation. The simulations
show that the binaries merge with extremely high eccentricity such that when
the gravitational waves are detectable by LISA, most of the binaries will have
eccentricities e > 0.9 though all will have circularized by the time they are
detectable by LIGO. We also investigate the implications for the formation and
growth of IMBHs and find that the inclusion of gravitational waves during the
encounter results in roughly half as many black holes ejected from the host
cluster for each black hole accreted onto the growing IMBH.


title:
Understanding Radio-Selected Thermal Sources in M 33: Ultraviolet,
  Optical, Near-Infrared, Spitzer Mid-Infrared, and Radio Observations

abstract:
  We present ultraviolet, optical, near-infrared, Spitzer mid-infrared, and
radio images of 14 radio-selected objects in M 33. These objects are thought to
represent the youngest phase of star cluster formation. We have detected the
majority of cluster candidates in M 33 at all wavelengths. From the near-IR
images, we derived ages 2-10 Myr, K_S-band extinctions (A_K_S) of 0-1 mag, and
stellar masses of 10^3-10^4 M_solar. We have generated spectral energy
distributions (SEDs) of each cluster from 0.1 micron to 160 microns. From these
SEDs, we have modeled the dust emission around these star clusters to determine
the dust masses (1-10^3 M_solar) and temperatures (40-90 K) of the clusters'
local interstellar medium. Extinctions derived from the JHK_S, Halpha, and UV
images are similar to within a factor of 2 or 3. These results suggest that
eleven of the fourteen radio-selected objects are optically-visible young star
clusters with a surrounding H II region, that two are background objects,
possibly AGN, and that one is a Wolf-Rayet star with a surrounding H II region.


title: The Multitude of Molecular Hydrogen Knots in the Helix Nebula

abstract:
  We present HST/NICMOS imaging of the H_2 2.12 \mu m emission in 5 fields in
the Helix Nebula ranging in radial distance from 250-450" from the central
star. The images reveal arcuate structures with their apexes pointing towards
the central star. Comparison of these images with comparable resolution ground
based images reveals that the molecular gas is more highly clumped than the
ionized gas line tracers. From our images, we determine an average number
density of knots in the molecular gas ranging from 162 knots/arcmin^2 in the
denser regions to 18 knots/arcmin^2 in the lower density outer regions. Using
this new number density, we estimate that the total number of knots in the
Helix to be ~23,000 which is a factor of 6.5 larger than previous estimates.
The total neutral gas mass in the Helix is 0.35 M_\odot assuming a mass of
\~1.5x10^{-5} M_\odot for the individual knots. The H_2 intensity, 5-9x10^{-5}
erg s^{-1} cm^{-2} sr^{-1}, remains relatively constant with projected distance
from the central star suggesting a heating mechanism for the molecular gas that
is distributed almost uniformly in the knots throughout the nebula. The
temperature and H_2 2.12 \mu m intensity of the knots can be approximately
explained by photodissociation regions (PDRs) in the individual knots; however,
theoretical PDR models of PN under-predict the intensities of some knots by a
factor of 10.


title: A mean redshift of 2.8 for Swift gamma-ray bursts

abstract:
  The exceptionally high luminosities of gamma-ray bursts (GRBs), gradually
emerging as extremely useful probes of star formation, make them promising
tools for exploration of the high-redshift Universe. Here we present a
carefully selected sample of Swift GRBs, intended to estimate in an unbiased
way the GRB mean redshift (z_mean), constraints on the fraction of
high-redshift bursts and an upper limit on the fraction of heavily obscured
afterglows. We find that z_mean = 2.8 and that at least 7% of GRBs originate at
z > 5. In addition, consistent with pre-Swift observations, at most 20% of
afterglows can be heavily obscured. The redshift distribution of the sample is
qualitatively consistent with models where the GRB rate is proportional to the
star formation rate in the Universe. We also report optical, near-infrared and
X-ray observations of the afterglow of GRB 050814, which was seen to exhibit
very red optical colours. By modelling its spectral energy distribution we find
that z = 5.3 +/- 0.3. The high mean redshift of GRBs and their wide redshift
range clearly demonstrates their suitability as efficient probes of galaxies
and the intergalactic medium over a significant fraction of the history of the
Universe.


title: Radio Emission from the Double-Pulsar System J0737-3039 Revisited

abstract:
  The double pulsar J0737-3039 is the only known system in which the
relativistic wind emitted by a radio pulsar demonstrably interacts with the
magnetosphere of another one. We report radio interferometric observations of
the J0737-3039 system with the VLA at three wavelengths, with each observation
spanning a full binary orbit. We detect J0737-3039 at 1.6 and 4.8 GHz, derive a
spectral index of -2.3 +/- 0.2, and place an upper limit on its flux density at
8.4 GHz. Orbital modulation is detected in the 1.6 GHz data with a significance
of ~2 sigma. Both orbital phase-resolved and phase-averaged measurements at 1.6
GHz are consistent with the entire flux density arising from the pulsed
emission of the two pulsars. Contrary to prior results, we find no evidence for
unpulsed emission, and limit it to less than 0.5 mJy (5 sigma).


title: Dark Energy Models in the w - w' Plane

abstract:
  We examine the behavior of dark energy models in the plane defined by w (the
equation of state parameter for the dark energy) and w' (the derivative of w
with respect to the logarithm of the scale factor). For non-phantom barotropic
fluids with positive squared sound speed, we find that w' < 3w(w+1), the
opposite of the bound on quintessence models previously derived by Caldwell and
Linder. Thus, these barotropic models and quintessence models for the dark
energy occupy disjoint regions in the w - w' plane. We also derive two new
bounds for quintessence models in the w - w' plane: the first is a general
bound for any scalar field with a monotonic potential, while the second
improves on the Caldwell-Linder bound for tracker quintessence models.
Observationally distinguishing barotropic models from quintessence models
requires \sigma(w') < 1+w.


title:
The Progenitors of Short-Hard Gamma-Ray Bursts from an Extended Sample
  of Events

abstract:
  The detection of the afterglow emission and host galaxies of short-hard
gamma-ray bursts (SHBs) is one of the most exciting recent astronomical
discoveries. Indications that SHB progenitors belong to old stellar
populations, in contrast to those of the long-soft GRBs, provide a strong clue
about their physical nature. Definitive conclusions however are limited by the
small number of SHBs with known hosts. Here, we present our investigation of
SHBs previously localized by the interplanetary network (IPN) using new and
archival optical and X-ray observations. We show that we can likely identify
the host galaxies/clusters for additional two bursts, significantly increasing
the sample of SHBs with known hosts and/or distances. In particular, we
determine that the bright SHB 790613 occurred within the rich galaxy cluster
Abell 1892, making it probably the nearest SHB currently known. We show that
the brightest galaxy within the error box of SHB 000607, at z=0.14, is most
likely the host galaxy of this event. Additionally, we rule out the existence
of galaxy overdensities (down to ~21mag) near the locations of two other SHBs,
and set a lower limit on their probable redshift. We combine our SHB sample
with events discovered recently by the Swift and HETE-2 missions, and
investigate the properties of the extended sample. Comparison to SNe Ia shows
that the progenitors of SHBs are typically older, implying a typical life time
of several Gy. We also show that it is unlikely that there is a significant
population of progenitors with life time shorter than 1Gy. This result
disfavors the popular model of NS-NS mergers as the progenitors of SHBs.


title: Low Mach Number Modeling of Type Ia Supernovae

abstract:
  We introduce a low Mach number equation set for the large-scale numerical
simulation of carbon-oxygen white dwarfs experiencing a thermonuclear
deflagration. Since most of the interesting physics in a Type Ia supernova
transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a
considerable increase in accuracy and savings in computer time compared with
frequently used compressible codes. Our equation set is derived from the fully
compressible equations using low Mach number asymptotics, but without any
restriction on the size of perturbations in density or temperature. Comparisons
with simulations that use the fully compressible equations validate the low
Mach number model in regimes where both are applicable. Comparisons to
simulations based on the more traditional anelastic approximation also
demonstrate the agreement of these models in the regime for which the anelastic
approximation is valid. For low Mach number flows with potentially finite
amplitude variations in density and temperature, the low Mach number model
overcomes the limitations of each of the more traditional models and can serve
as the basis for an accurate and efficient simulation tool.


title: Footprints of Statistical Anisotropies

abstract:
  We propose and develop a formalism to describe and constrain statistically
anisotropic primordial perturbations. Starting from a decomposition of the
primordial power spectrum in spherical harmonics, we find how the temperature
fluctuations observed in the CMB sky are directly related to the coefficients
in this harmonic expansion. Although the angular power spectrum does not
discriminate between statistically isotropic and anisotropic perturbations, it
is possible to define analogous quadratic estimators that are direct measures
of statistical anisotropy. As a simple illustration of our formalism we test
for the existence of a preferred direction in the primordial perturbations
using full-sky CMB maps. We do not find significant evidence supporting the
existence of a dipole component in the primordial spectrum.


title:
Star Formation Rates and Extinction Properties of IR-Luminous Galaxies
  in the Spitzer First Look Survey

abstract:
  We investigate the instantaneous star formation rates (SFR) and extinction
properties for a large (N=274), near-infrared (2.2 micron) + mid-infrared (24
micron) selected sample of normal to ultra-luminous infrared galaxies (ULIRGs)
[10^9<L_{IR}/L_{sun}<10^12.5] with <z>~0.8 in the Spitzer Extragalactic First
Look Survey. We combine Spitzer MIPS 24-micron observations with
high-resolution, optical Keck Deimos spectroscopy to derive optical
emission-line and infrared star formation rates (SFR_{opt} & SFR_{IR},
respectively). Direct comparison of these SFR diagnostics reveals that our
sample exhibits a wide range of extinction (1.0<Av<4.0 mag). This is after
removing spectroscopic and IRAC color-selected AGN candidates that account for
12% of the sample. Objects with SFRs of a few solar masses per year have Av
values consistent with those of normal spirals (Av~1.0 mag). By contrast, LIRGs
at z>1, which make up a large fraction of our sample, have SFR~100 M_{sun}/yr
and <Av>~2.5 mag. This translates to a 97% mean attenuation of the [OII]
forbidden line doublet, with the most extreme sources having as much as 99.7%
of their [OII] line flux extinguished by dust. Based on a SFR_{IR}/SFR_{opt}
diagnostic, we derive an IR-luminosity-dependent Av^{IR} function
[Av^{IR}=0.75*log(L_{IR}/L_{sun})-6.35 mag] that we use to extinction correct
our emission line luminosities. Application of this correction results in a
correlation between SFR_{IR} and SFR_{opt} that has a dispersion of 0.2 dex.
Investigation of the Av dependence on redshift reveals that for a fixed L_{IR},
there is no significant Av evolution. The mean attenuation of our sample is
intermediate between that of local optical/UV- and radio-selected samples and
has a marginally stronger L_{IR} dependence.


title: Interacting Chaplygin gas

abstract:
  We investigate a kind of interacting Chaplygin gas model in which the
Chaplygin gas plays the role of dark energy and interacts with cold dark matter
particles. We find that there exists a stable scaling solution at late times
with the Universe evolving into a phase of steady state. Furthermore, the
effective equation of state of Chaplygin gas may cross the so-called phantom
divide $w=-1$. The above results are derived from continuity equations, which
means that they are independent of any gravity theories. Assuming standard
general relativity and a spatially flat FRW metric, we also find the
deceleration parameter is well consistent with current observations.


title:
Non-thermal X-ray and Gamma-ray Emission from the Colliding Wind Binary
  WR140

abstract:
  WR140 is the archetype long-period colliding wind binary (CWB) system, and is
well known for dramatic variations in its synchrotron emission during its
7.9-yr, highly eccentric orbit. This emission is thought to arise from
relativistic electrons accelerated at the global shocks bounding the
wind-collision region (WCR). The presence of non-thermal electrons and ions
should also give rise to X-ray and gamma-ray emission from several separate
mechanisms, including inverse-Compton cooling, relativistic bremsstrahlung, and
pion decay. We describe new calculations of this emission and make some
preliminary predictions for the new generation of gamma-ray observatories. We
determine that WR140 will likely require several Megaseconds of observation
before detection with INTEGRAL, but should be a reasonably strong source for
GLAST.


title: Detailed theoretical predictions of the outskirts of dark matter halos

abstract:
  In the present work we describe the formalism necessary to derive the
properties of dark matter halos beyond two virial radius using the spherical
collapse model (without shell crossing), and provide the framework for the
theoretical prediction presented in Prada et al. (2005). We show in detail how
to obtain within this model the probability distribution for the
spherically-averaged enclosed density at any radii P(delta,r). Using this
probability distribution, we compute the most probable and mean density
profiles, which turns out to differ considerably from each other. We also show
how to obtain the typical profile, as well as the probability distribution and
mean profile for the spherically averaged radial velocity. Two probability
distributions are obtained: a first one is derived using a simple assumption,
that is, if Q is the virial radius in Lagrangian coordinates, then the enclosed
linear contrast delta_l(q,Q) must satisfy the condition that delta_l(q=Q) =
delta_vir, where delta_vir is the linear density contrast within the virial
radius Rvir at the moment of virialization. Then we introduce an additional
constraint to obtain a more accurate P(delta,r) which reproduces to a higher
degree of precision the distribution of the spherically averaged enclosed
density found in the simulations. This new constraint is delta_l(q,Q) <
delta_vir for all q > Q, which means that there are no radii larger than Rvir
where the density contrast is larger than that used to define the virial
radius. Finally, we compare in detail our theoretical predictions for the
probability distributions with the results found in the simulations.


title:
A robust sample of submillimetre galaxies: constraints on the prevalence
  of dusty, high-redshift starbursts

abstract:
  The modest significance of most sources detected in current submm surveys can
potentially compromise some analyses due to the inclusion of spurious sources
in catalogues typically selected at >3.0-3.5sigma. Here, we develop and apply a
dual-survey extraction technique to SCUBA and MAMBO images of the Lockman Hole.
Cut above 5sigma, our catalogue of SMGs is more robust than previous samples,
with a reduced likelihood of real, but faint SMGs (beneath and around the
confusion limit) entering via superposition with noise. The effective flux
limit of the survey is well matched to our deep 1.4-GHz image. The former is
sensitive to luminous, dusty galaxies at extreme redshifts whilst the latter
probes the z<3 regime. A high fraction of our robust SMGs (~80%) have radio
counterparts which, given the ~10% contamination by spurious sources, suggests
that very distant SMGs (z>>3) are unlikely to make up more than ~10% of the
bright SMG population. This implies that almost all of the bright SMG
population is amenable to study via the deepest current radio imaging. We use
these radio counterparts to provide an empirical calibration of the positional
uncertainty in SMG catalogues. We then go on to outline the acquisition of
redshifts for radio-identified SMGs, from sample selection in the submm, to
counterpart selection in the radio and optical/IR, to slit placement on
spectrograph masks. We determine a median of z=2.05 +/- 0.41 from a sample of
six secure redshifts for unambigious radio-identified submm sources and z=2.14
+/- 0.27 when we include submm sources with multiple radio counterparts and/or
less reliable redshifts. These figures are consistent with previous estimates,
suggesting that our knowledge of the median redshift of bright SMGs population
has not been biased by the low significance of the source catalogues employed.


title: Gamma-rays from PSR B1259 -63

abstract:
  The high-energy gamma-ray emission discovered using the H.E.S.S. telescopes
from the binary system PSR B1259 -63, is modelled using an extension of the
approach that successfully predicted it. We find that the simultaneous INTEGRAL
and H.E.S.S. data permit both a model with dominant radiative losses, high
pulsar wind Lorentz factor and modest efficiency as well as one with dominant
adiabatic losses, a slower wind and higher efficiency. Additional,
simultaneous, X-ray and TeV data sets are needed to lift this degeneracy.


title:
High Resolution and Broad Band Spectra of Low Mass X-ray Binaries: A
  Comparison between Black Holes and Neutron Stars

abstract:
  A common question about compact objects in high energy astrophysics is
whether it is possible to distinguish black hole from neutron star systems with
some other property that is not the mass of the compact object. Up to now a few
characteristics have been found which are typical of neutron stars (like quasi
periodic oscillations at kHz frequencies or type-I X-ray bursts), but in many
respects black hole and neutron star systems show very similar behaviors. We
present here a spectral study of low mass X-ray binaries containing neutron
stars and show that these systems have spectral characteristics that are very
similar to what is found for black hole systems. This implies that it is
unlikely we can distinguish between black holes and neutron stars from their
X-ray spectra, except for the fact that black hole systems show sometimes a
more extreme behavior with respect to neutron star systems.


title: The high-energy gamma-ray light curve of PSR B1259 -63

abstract:
  The high-energy gamma-ray light curve of the binary system PSR B1259 -63, is
computed using the approach that successfully predicted the spectrum at
periastron. The simultaneous INTEGRAL and H.E.S.S. spectra taken 16 days after
periastron currently permit both a model with dominant radiative losses, high
pulsar wind Lorentz factor and modest efficiency as well as one with dominant
adiabatic losses, a slower wind and higher efficiency. In this paper we shown
how the long-term light curve may help to lift this degeneracy.


title:
Interaction between a galactic disk and a live dark halo with an
  anisotropic velocity distribution

abstract:
  We have extended previous analytical studies of the interaction of dark halos
with galactic disks by introducing for the halo particles anisotropic
distribution functions in phase space. For this purpose we have employed the
shearing sheet model of a patch of a galactic disk embedded in a homogeneous
halo. We find that velocity anisotropy increases considerably the maximum
growth factor of perturbations in the disk.


title: Structure and dynamics of the Shapley Supercluster

abstract:
  We present results of our wide-field redshift survey of galaxies in a 285
square degree region of the Shapley Supercluster (SSC), based on a set of 10529
velocity measurements (including 1201 new ones) on 8632 galaxies obtained from
various telescopes and from the literature. Our data reveal that the main plane
of the SSC (v~ 14500 km/s) extends further than previous estimates, filling the
whole extent of our survey region of 12~degrees by 30~degrees on the sky (30 x
75~h-1 Mpc). There is also a connecting structure associated with the slightly
nearer Abell~3571 cluster complex (v~ 12000km/s. These galaxies seem to link
two previously identified sheets of galaxies and establish a connection with a
third one at V= 15000 km/s near R.A.= 13h. They also tend to fill the gap of
galaxies between the foreground Hydra-Centaurus region and the more distant
SSC. In the velocity range of the Shapley Supercluster (9000 km/s < cz < 18000
km/s), we found redshift-space overdensities with b\_j < 17.5 of ~5.4 over the
225 square degree central region and ~3.8 in a 192 square degree region
excluding rich clusters. Over the large region of our survey, we find that the
intercluster galaxies make up 48 per cent of the observed galaxies in the SSC
region and, accounting for the different completeness, may contribute nearly
twice as much mass as the cluster galaxies. In this paper, we discuss the
completeness of the velocity catalogue, the morphology of the supercluster, the
global overdensity, and some properties of the individual galaxy clusters in
the Supercluster.


title: Looking at quasars through galaxies

abstract:
  Observations of quasars (QSOs) shining through or close to galaxies offer a
way to probe the properties of the foreground matter through dust extinction
and gravitational lensing. In this paper the feasibility of measuring the dust
extinction properties is investigated using the backlitting of QSOs. We test
our method to search for QSOs affected by intervening extinction, by matching
the coordinates in the SDSS QSO DR3 catalogue with the New York University
Value-Added Galaxy Catalog. In total, 164 QSO-galaxy pairs were found with a
distance of less than 30 kpc between the galaxy centre and the QSO
line-of-sight at the galaxy redshift. Investigating the QSO colours with
multiband SDSS photometry, two pairs with galaxy redshifts z < 0.08 were found
to be particularly interesting in that the QSOs show evidence of heavy Galactic
type extinction with R_v ~ 3.1 at very large optical radii in the foreground
spiral galaxies. With the available data, it remains inconclusive whether the
two pairs can be explained as statistical colour outliers, by host extinction
or if they provide evidence of dust in the outskirts of spiral galaxies. Deeper
galaxy catalogues and/or higher resolution follow-up QSO spectra would help in
resolving this problem. We also analyse five QSOs reported in the literature
with spectroscopic absorption features originating from an intervening system.
These systems are at higher redshifts than the other two and we find in most
cases significantly lower best fit values of R_v. The wide range of preferred
values of R_v found, although affected by substantial uncertainties, already
indicates that the dust properties in other galaxies may be different from the
Milky Way. Furthermore, the available data suggests a possible evolution in the
dust properties with redshift, with lower R_v at high z.


title:
Interpreting the galaxy group CG J1720-67.8 through evolutionary
  synthesis models

abstract:
  This paper is part of a series devoted to a detailed analysis of the
properties of the compact group CG J1720-67.8 and its member galaxies with the
aim of sheding light on its evolutionary history. Here we interpret our
previously published observational results through comparison with chemically
consistent spectrophotometric evolutionary synthesis models in order to gain
further clues to the evolutionary history of the galaxies in this group. In
order to reduce the number of free parameters, we considered the simplest case
of a single burst of star formation turned on after 11 - 12 Gyr of undisturbed
galaxy evolution. However, we also briefly explore the effect of multiple,
interaction-induced bursts of star formation. We find that the two spiral
galaxies are consistent with interaction induced strong starbursts switched on
\~ 40 to 180 Myr ago and still active. For the early-type galaxy a <~ 0.9 - 1.3
Gyr old star formation event (depending on the considered model) appears
consistent with observed properties. The comparison with models cannot rule out
the possibility that this galaxy is already the result of a merger.
Alternatively, a star formation episode in this galaxy might have been
triggered by a gas inflow as a consequence of the interaction with the
companion galaxies. Estimates of galaxy masses are derived from the comparison
with the models. Finally our results are discussed in comparison with other
well studied poor galaxy systems.


title:
Homogeneous comparison of directly detected planet candidates: GQ Lup,
  2M1207, AB Pic

abstract:
  We compile the observational evidence for the three recently presented planet
candidates imaged directly and derive in a homogeneous way their temperatures
and masses. For both AB Pic b and 2M1207 b, we derive a larger temperature
range than in Chauvin et al. (2004, 2005b). AB Pic b appears to be quite
similar as GQ Lup b, but older. According to the Tucson and Lyon models, all
three companions could either be planets or brown dwarfs. According to the
Wuchterl formation model, the masses seem to be below the D burning limit. We
discuss whether the three companions can be classified as planets, and whether
the three systems are gravitationally bound and long-term stable.


title: Growth of Spirals: Secular or Driven by Mergers ?

abstract:
  The physical phenomena contributing to the galaxy growth can be tested all
the way to z= 1. Galaxy mass, extinction, star formation and gas metal
abundance can be measured in a robust way, as well as the distribution of the
galaxy morphologies. I discuss here the observational methods and their
accuracy. Physical quantities can be evaluated with uncertainties much lower
than 0.3 dex, if they are based on 2 sets of independent measurements. For
example, at a given IMF, the star formation rate is well estimated by combining
flux measurements of the extinction corrected Balmer line and of the mid-IR
continuum.
  Spiral mass growth had occurred from gas accretion and from merging. Gas
accretion can explain at most half of the spiral mass growth: at moderate
redshift, the numerous population of compact, merger and irregular galaxies
requires another origin. A spiral rebuilding scenario is able to reproduce all
the evolutionary trends observed since z~1, and could be at the origin of the
present-day, numerous population of early type spirals.


title:
Intra-group diffuse light in compact groups of galaxies. HCG 79, HCG 88
  and HCG 95

abstract:
  Deep $B$ and $R$ images of three Hickson Compact Groups, HCG 79, HCG 88 and
HCG 95, were analyzed using a new wavelet technic to measure possible
intra-group diffuse light present in these systems. The method used, OV\_WAV,
is a wavelet technic particularly suitable to detect low-surface brightness
extended structures, down to a $S/N = 0.1$ per pixel, which corresponds to a
5-$\sigma$-detection level in wavelet space. The three groups studied are in
different evolutionary stages, as can be judged by their very different
fractions of the total light contained in their intra-group halos: $46\pm11$%
for HCG 79 and $11\pm26$% for HCG 95, in the $B$ band, and HCG 88 had no
component detected down to a limiting surface brightness of $29.1 B mag
arcsec^{-2}$. For HCG 95 the intra-group light is red, similar to the mean
colors of the group galaxies themselves, suggesting that it is formed by an old
population with no significant on-going star formation. For HCG 79, however,
the intra-group material has significantly bluer color than the mean color of
the group galaxies, suggesting that the diffuse light may, at least in part,
come from stripping of dwarf galaxies which dissolved into the group potential
well.


title: A new definition of the intermediate group of gamma-ray bursts

abstract:
  Gamma-ray bursts can be divided into three groups ("short", "intermediate",
"long") with respect to their durations. This classification is somewhat
imprecise, since the subgroup of intermediate duration has an admixture of both
short and long bursts. In this paper a physically more reasonable definition of
the intermediate group is presented, using also the hardnesses of the bursts.
It is shown again that the existence of the three groups is real, no further
groups are needed. The intermediate group is the softest one. From this new
definition it follows that 11% of all bursts belong to this group. An
anticorrelation between the hardness and the duration is found for this
subclass in contrast to the short and long groups. Despite this difference it
is not clear yet whether this group represents a physically different
phenomenon.


title:
Absolute polarisation position angle profiles of southern pulsars at 1.4
  and 3.1 GHz

abstract:
  We present here a direct comparison of the polarisation position angle (PA)
profiles of 17 pulsars, observed at 1.4 and 3.1 GHz. Absolute PAs are obtained
at each frequency, permitting a measurement of the difference in the profiles.
By doing this, we obtain more precise rotation measure (RM) values for some of
the pulsars in the current catalogue. We find that, apart from RM corrections,
there are small, pulse longitude dependent differences in PA with frequency.
Such differences go beyond the interpretation of a geometrical origin. We
describe in detail the PA evolution between the two frequencies and discuss
possible causes, such as orthogonal and non-orthogonal polarisation modes of
emission. We also use the PA and total power profiles to estimate the
difference in emission height at which the two frequencies originate. In our
data sample, there are changes in the relative strengths of different pulse
components, especially overlapping linearly polarised components, which
coincide with intrinsic changes of the PA profile, resulting in interesting PA
differences between the two frequencies.


title: Shock-cloud interaction in the Vela SNR observed with XMM-Newton

abstract:
  We analyzed an XMM-Newton EPIC observation of a bright knot, named FilD, in
the northern rim of the Vela SNR, where the shock has encountered a cloud. The
good combination of sensitivity, spectral, and spatial resolution allowed us to
describe the internal structure of the observed ISM clouds and to obtain
estimates of their temperature, density, O, Ne, and Fe abundances, and of their
extension along the line of sight. We also examined the interaction of the
shock with the FilD knot and estimated that the time elapsed from the shock
impact is about one cloud crushing time. Our analysis allowed us to conclude
that the observed X-ray emission is best explained by the propagation of
transmitted shocks through ISM inhomogeneities with an inward increasing
density profile. We found that the interaction with the shock determines the
heating of the inner part of the clouds and the evaporation of the outer part.


title:
Supermassive Black Hole Mass Functions at Intermediate Redshifts from
  Spheroid and AGN Luminosity Functions

abstract:
  Redshift evolution of supermassive black hole mass functions (BHMFs) is
investigated up to z ~ 1. BHMFs at intermediate redshifts are calculated in two
ways. One way is from early-type galaxy luminosity functions (LFs); we assume
an M_BH - L_sph correlation at a redshift by considering a passive evolution of
L_sph in the local relationship. The resultant BHMFs (spheroid-BHMFs) from LFs
of red sequence galaxies indicates a slight decrease of number density with
increasing redshift at M_BH > 10^{7.5-8} M_solar. Since a redshift evolution in
slope and zeropoint of the M_BH - L_sph relation is unlikely to be capable of
making such an evolution in BHMF, the evolution of the spheroid-BHMFs is
perhaps due mainly to the decreasing normalization in the galaxy LFs. We also
investigate how spheroid-BHMFs are affected by uncertainties existing in the
derivation in detail. The other way of deriving a BHMF is based on the
continuity equation for number density of SMBHs and LFs of active galactic
nucleus (AGN). The resultant BHMFs (AGN-BHMFs) show no clear evolution out to z
= 1 at M_BH > 10^8 M_solar, but exhibit a significant decrease with redshift in
the lower mass range. Comparison of the spheroid-BHMFs with the AGN-BHMFs
suggests that at M_BH > 10^{8} M_solar, the spheroid-BHMFs are broadly
consistent with the AGN-BHMFs out to z ~ 1. The agreement between the
spheroid-BHMFs and the AGN-BHMFs appears to support that most of the SMBHs are
already hosted by massive spheroids at z ~ 1 and they evolve without
significant mass growth since then.


title:
Measurement of Throughput Variation Across A Large Format Volume-Phase
  Holographic Grating

abstract:
  In this paper, we report measurements of diffraction efficiency and angular
dispersion for a large format (~ 25 cm diameter) Volume-Phase Holographic (VPH)
grating optimized for near-infrared wavelengths (0.9 -- 1.8 micron). The aim of
this experiment is to see whether optical characteristics vary significantly
across the grating. We sampled three positions in the grating aperture with a
separation of 5 cm between each. A 2 cm diameter beam is used to illuminate the
grating. At each position, throughput and diffraction angle were measured at
several wavelengths. It is found that whilst the relationship between
diffraction angle and wavelength is nearly the same at the three positions, the
throughputs vary by up to ~ 10% from position to position. We explore the
origin of the throughput variation by comparing the data with predictions from
coupled-wave analysis. We find that it can be explained by a combination of
small variations over the grating aperture in gelatin depth and/or refractive
index modulation amplitude, and amount of energy loss by internal absorption
and/or surface reflection.


title:
Near-Infrared, Kilosecond Variability of the Wisps and Jet in the Crab
  Pulsar Wind Nebula

abstract:
  We present a time-lapse sequence of 20 near-infrared (J- and K'-band)
snapshots of the central 20x20 arcsec of the Crab pulsar wind nebula, taken at
subarcsecond resolution with the Hokupa'a/QUIRC adaptive optics camera on the
Gemini North Telescope, and sampled at intervals of 10 min and 24 hr. It is
observed that the equatorial wisps and polar knots in the termination shock of
the pulsar wind appear to fluctuate in brightness on kilosecond time-scales.
Maximum flux variations of +/-24 +/-4 and +/-14 +/-4 per cent relative to the
mean (in 1.2 ks) are measured for the wisps and knots respectively, with
greatest statistical significance in J band where the nebula background is less
prominent. The J and K' flux densities imply different near-infrared spectra
for the nonthermal continuum emission from the wisps and outermost polar knot
(sprite), giving F_nu ~ nu^{-0.56+/-0.12} and F_nu ~ nu^{-0.21+/-0.13)
respectively. The data are compared with existing optical and UV photometry and
applied to constrain theories of the variability of the wisps (relativistic
ion-cyclotron instability) and knots (relativistic fire hose instability).


title:
Accretion of helium and metal-rich gas onto neutron stars and black
  holes at high luminosities

abstract:
  Ultraluminous X-ray sources fed by Wolf-Rayet star winds and X-ray bursters
in ultracompact binaries with He or C white dwarfs have accretion disks, whose
properties may significantly differ from those of pure H alpha-accretion disks.
We have therefore included the dependence on charge number Z and mean molecular
weights mu_{e/I} into the Shakura and Sunyaev (1973) scaling relations for the
key parameters of the disk. Furthermore, we also consider the case of the
pseudo-Newtonian potential of Paczynsky and Wiita (1980). These scaling
relations might become useful, e.g., when estimating the illumination
efficiency of the external parts of the disk. We also address the changes in
the structure of the boundary (spreading) layer on the surface of neutron
stars, occurring in the case of H depleted accretion disks.


title: Isotopes Tell Origin and Operation of the Sun

abstract:
  The Iron Sun formed on the collapsed core of a supernova and now acts as a
magnetic plasma diffuser, as did the precursor star, separating ions by mass.
This process covers the solar surface with lightweight elements and with
lighter isotopes of each element. Running difference images expose rigid,
iron-rich structures below the fluid photosphere made of lightweight elements.
The energy source for the Sun and ordinary stars seems to be neutron-emission
and neutron-decay, with partial fusion of the decay product, rather than simple
fusion of hydrogen into helium or heavier elements. Neutron-emission from the
solar core and neutron-decay generate about sixty five percent of solar
luminosity and H-fusion generates about thirty-five percent. The upward flow of
H ions maintains mass-separation in the Sun. Only about one percent of this
neutron decay product survives its upward journey to depart as solar-wind
hydrogen.


title: Beyond Gravitoelectromagnetism: Critical Speed in Gravitational Motion

abstract:
  A null ray approaching a distant astronomical source appears to slow down,
while a massive particle speeds up in accordance with Newtonian gravitation.
The integration of these apparently incompatible aspects of motion in general
relativity is due to the existence of a critical speed. Dynamics of particles
moving faster than the critical speed could then be contrary to Newtonian
expectations. Working within the framework of gravitoelectromagnetism, the
implications of the existence of a critical speed are explored. The results are
expected to be significant for high energy astrophysics.


title: The Cosmic Microwave Background anisotropies: open problems

abstract:
  The standard inflationary model presents a simple scenario within which the
homogeneity, isotropy and flatness of the universe appear as natural outcomes
and, in addition, fluctuations in the energy density are originated during the
inflationary phase. These seminal density fluctuations give rise to
fluctuations in the temperature of the Cosmic Microwave Background (CMB) at the
decoupling surface. Afterward, the CMB photons propagate almost freely, with
slight gravitational interactions with the evolving gravitational field present
in the large scale structure (LSS) of the matter distribution and a low
scattering rate with free electrons after the universe becomes reionized. These
secondary effects slightly change the shape of the intensity and polarization
angular power spectra (APS) of the radiation. The APS contain very valuable
information on the parameters characterizing the background model of the
universe and those parametrising the power spectra of both matter density
perturbations and gravitational waves. In the last few years data from
sensitive experiments have allowed a good determination of the shape of the
APS, providing for the first time a model of the universe very close to
spatially flat. In particular the WMAP first year data, together with other CMB
data at higher resolution and other cosmological data sets, have made possible
to determine the cosmological parameters with a precision of a few percent. The
most striking aspect of the derived model of the universe is the unknown nature
of most of its energy contents. This and other open problems in cosmology
represent exciting challenges for the CMB community. The future ESA Planck
mission will undoubtely shed some light on these remaining questions.


title: Mira variables in the Galactic bulge with OGLE-II data

abstract:
  We have extracted a total of 1968 Mira variables from the OGLE-II data base
in the Galactic bulge region. Among them, 1960 are associated with 2MASS
sources, and 1541 are further identified with MSX point sources. Their
photometric properties are compared with those of Mira variables in the Large
and Small Magellanic Clouds. We have found that mass-losing stars with
circumstellar matter are reddened such that the colour dependence of the
absorption coefficient is similar to that of interstellar matter. We also
discuss the structure of the bulge. The surface number density of the bulge
Mira variables is well correlated with the 2.2-micron surface brightness
obtained by the COBE satellite. Using this relation, the total number of Mira
variables in the bulge is estimated to be about 600,000. The logP-K relation of
the Mira variables gives their space distribution which supports the well-known
asymmetry of the bar-like bulge.


title: The Star Clusters of the Small Magellanic Cloud: Structural Parameters

abstract:
  We present structural parameters for 204 stellar clusters in the Small
Magellanic Cloud derived from fitting King and Elson, Fall, & Freeman model
profiles to the V-band surface brightness profiles as measured from the
Magellanic Clouds Photometric Survey images. Both King and EFF profiles are
satisfactory fits to the majority of the profiles although King profiles are
generally slightly superior to the softened power-law profiles of Elson, Fall,
and Freeman and provide statistically acceptable fits to ~90% of the sample. We
find no correlation between the preferred model and cluster age. The only
systematic deviation in the surface brightness profiles that we identify is a
lack of a central concentration in a subsample of clusters, which we designate
as "ring" clusters. In agreement with previous studies, we find that the
clusters in the SMC are significantly more elliptical than those in the Milky
Way. However, given the mean age difference and the rapid destruction of these
systems, the comparison between SMC and MW should not directly be interpreted
as either a difference in the initial cluster properties or their subsequent
evolution. We find that cluster ellipticity correlates with cluster mass more
strongly than with cluster age. We identify several other correlations (central
surface brightness vs. local background density, core radius vs. tidal force,
size vs. distance) that can be used to constrain models of cluster evolution in
the SMC.


title: Coincidence Problem in an Oscillating Universe

abstract:
  We analyze an oscillating universe model in brane world scenario. The
oscillating universe cycles through a series of expansions and contractions and
its energy density is dominated by dust matter at early-time expansion phase
and by phantom dark energy at late-time expansion phase. We find that the
period of the oscillating universe is not sensitive to the tension of the
brane, but sensitive to the equation-of-state parameter $w$ of the phantom dark
energy, and the ratio of the period to the current Hubble age approximately
varies from 3 to 9 when the parameter $w$ changes from -1.4 to -1.1. The
fraction of time that the oscillating universe spends in the coincidence state
is also comparable to the period of the oscillating universe. This result
indicates that the coincidence problem can be significantly ameliorated in the
oscillating universe without singularity.


title:
Induced planet formation in stellar clusters - a parameter study of
  star-disk encounters

abstract:
  We present a parameter study of the possibility of tidally triggered disk
instability. Using a restricted N-body model which allows for a survey of an
extended parameter space, we show that a passing dwarf star with a mass between
0.1 and 1 M_sun can probably induce gravitational instabilities in the
pre-planetary solar disk for prograde passages with minimum separations below
80-170 AU for isothermal or adiabatic disks. Inclined and retrograde encounters
lead to similar results but require slightly closer passages. Such encounter
distances are quite likely in young moderately massive star clusters (Scally &
Clarke 2001; Bonnell et al. 2001). The induced gravitational instabilities may
lead to enhanced planetesimal formation in the outer regions of the
protoplanetary disk, and could therefore be relevant for the existence of
Uranus and Neptune, whose formation timescale of about 100 Myr (Wuchterl,
Guillot & Lissauer 2000) is inconsistent with the disk lifetimes of about a few
Myr according to observational data by Haisch, Lada & Lada (2001). The
relatively small gas/solid ratio in Uranus and Neptune can be matched if the
perturbing fly-by occurred after early gas depletion of the solar system, i.e.
when the solar system was older than about 5 Myr.
  We also confirm earlier results by Heller (1993) that the observed 7 degree
tilt of the solar equatorial plane relative to the ecliptic plane could be the
consequence of such a close encounter.


title:
GRB 050117: Simultaneous Gamma-ray and X-ray Observations with the Swift
  Satellite

abstract:
  The Swift Gamma-Ray Burst Explorer performed its first autonomous, X-ray
follow-up to a newly detected GRB on 2005 January 17, within 193 seconds of the
burst trigger by the Swift Burst Alert Telescope. While the burst was still in
progress, the X-ray Telescope obtained a position and an image for an
un-catalogued X-ray source; simultaneous with the gamma-ray observation. The
XRT observed flux during the prompt emission was 1.1 x 10^{-8} ergs cm^{-2}
s^{-1} in the 0.5-10 keV energy band. The emission in the X-ray band decreased
by three orders of magnitude within 700 seconds, following the prompt emission.
This is found to be consistent with the gamma-ray decay when extrapolated into
the XRT energy band. During the following 6.3 hours, the XRT observed the
afterglow in an automated sequence for an additional 947 seconds, until the
burst became fully obscured by the Earth limb. A faint, extremely slowly
decaying afterglow, alpha=-0.21$, was detected. Finally, a break in the
lightcurve occurred and the flux decayed with alpha<-1.2$. The X-ray position
triggered many follow-up observations: no optical afterglow could be confirmed,
although a candidate was identified 3 arcsecs from the XRT position.


title:
Young Jupiters are Faint: New Models of the Early Evolution of Giant
  Planets

abstract:
  Here we show preliminary calculations of the cooling and contraction of a 2
MJ planet. These calculations, which are being extended to 1-10 MJ, differ from
other published "cooling tracks" in that they include a core accretion-gas
capture formation scenario, the leading theory for the formation of gas giant
planets. We find that the initial post-accretionary intrinsic luminosity of the
planet is ~3 times less than previously published models which use arbitrary
initial conditions. These differences last a few tens of millions of years.
Young giant planets are intrinsically fainter than has been previously
appreciated. We also discuss how uncertainties in atmospheric chemistry and the
duration of the formation time of giant planets lead to challenges in deriving
planetary physical properties from comparison with tabulated model values.


title: The Circumstellar Environments of NML Cyg and the Cool Hypergiants

abstract:
  We present high-resolution HST WFPC2 images of compact nebulosity surrounding
the cool M-type hypergiants NML Cyg, VX Sgr and S Per. The powerful OH/IR
source NML Cyg exhibits a peculiar bean-shaped asymmetric nebula that is
coincident with the distribution of its H2O vapor masers. We show that NML
Cyg's circumstellar envelope is likely shaped by photo-dissociation from the
powerful, nearby association Cyg OB2 inside the Cygnus X superbubble. The OH/IR
sources VX Sgr and S Per have marginally resolved envelopes. S Per's
circumstellar nebula appears elongated in a NE/SW orientation similar to that
for its OH and H2O masers, while VX Sgr is embedded in a spheroidal envelope.
We find no evidence for circumstellar nebulosity around the intermediate-type
hypergiants rho Cas, HR 8752, HR 5171a, nor the normal M-type supergiant mu
Cep. We conclude that there is no evidence for high mass loss events prior to
500-1000 yrs ago for these four stars.


title: Eclipses and orbital modulations in binary pulsar PSR J0737-3039

abstract:
  Binary radio pulsar system J0737-3039 provides an exceptional opportunity to
study innermost structure of pulsar magnetospheres due to very tight orbit,
favorable directions of pulsars' rotation and magnetic axes and extremely
fortuitous orientation of the orbit. In this system the millisecond pulsar A is
eclipsed once per orbit. During eclipse a clear modulation at the 2.77 s period
of pulsar B is seen, pointing unambiguously to magnetospheric origin of
eclipses. A simple geometric model, based on the idea that the radio pulses are
attenuated by synchrotron absorption on the closed magnetic field lines of
pulsar B, can successfully reproduces the eclipse light curves down to
intricate details. This detailed agreement confirms the dipolar structure of
the neutron star's magnetic field.
  The model gives clear predictions for temporal evolution of eclipse profile
due to geodetic precession of pulsar B.
  In addition, pulsar B shows orbital modulations of intensity, being
especially bright at two short orbital phases. We showed that these modulations
are due to distortion of pulsar B magnetosphere by pulsar A wind which produces
orbital phase-dependent changes of the direction along which radio waves are
emitted. Thus, pulsar B is intrinsically bright at all times but its radiation
beam misses the Earth at most orbital phases.


title:
Results from the Wide Angle Search for Planets Prototype (WASP0) III:
  Planet Hunting in the Draco Field

abstract:
  The Wide Angle Search for Planets prototype (WASP0) is a wide-field
instrument used to search for extra-solar planets via the transit method. Here
we present the results of a monitoring program which targeted a 9-degree field
in Draco. WASP0 monitored 35000 field stars for two consecutive months.
Analysis of the lightcurves resulted in the detection of 11 multi-transit
candidates and 3 single-transit candidates, two of which we recommend for
further follow-up. Monte-Carlo simulations matching the observing parameters
estimate the expected number of transit candidates from this survey. A
comparison of the expected number with the number of candidates detected is
used to discuss limits on planetary companions to field stars.


title: X-ray Emission from Megamaser Galaxy IC 2560

abstract:
  Observation of the H2O megamaser galaxy IC 2560 with the Chandra Observatory
reveals a complex spectrum composed of soft X-ray emission due to
multi-temperature thermal plasma, and a hard continuum with strong emission
lines. The continuum is most likely a Compton reflection (reprocessing) of
primary emission that is completely absorbed at least up to 7 keV. The lines
can be identified with fluorescence from Si, S and Fe in the lowest ionization
stages. The equivalent widths of the Si and S lines are broadly compatible with
those anticipated for reprocessing by optically thick cold plasma of Solar
abundances, while the large equivalent width of the Fe line requires some
overabundance of iron. A contribution to the line from a transmitted component
cannot be ruled out, but the limits on the strength of the Compton shoulder
make it less likely. From the bolometric luminosity of the nuclear region, we
infer that the source radiates at 1 - 10% of its Eddington luminosity, for an
adopted central mass of 3 million Solar masses. The overall spectrum is
consistent with the hypotheses that the central engines powering the detected
megamsers in accretion disks are obscured from direct view by the associated
accretion disk material itself, and that there is a correlation between the
occurrence of megamaser emission and Compton-thick absorption columns. For the
11 known galaxies with both column density measurements and maser emission
believed to arise from accretion disks, eight AGN are Compton thick.


title:
The Origin of Episodic Accretion Bursts in the Early Stages of Star
  Formation

abstract:
  We study numerically the evolution of rotating cloud cores, from the collapse
of a magnetically supercritical core to the formation of a protostar and the
development of a protostellar disk during the main accretion phase. We find
that the disk quickly becomes unstable to the development of a spiral structure
similar to that observed recently in AB Aurigae. A continuous infall of matter
from the protostellar envelope makes the protostellar disk unstable, leading to
spiral arms and the formation of dense protostellar/protoplanetary clumps
within them. The growing strength of spiral arms and ensuing redistribution of
mass and angular momentum creates a strong centrifugal disbalance in the disk
and triggers bursts of mass accretion during which the dense
protostellar/protoplanetary clumps fall onto the central protostar. These
episodes of clump infall may manifest themselves as episodes of vigorous
accretion rate (\ge 10^{-4} M_sun/yr) as is observed in FU Orionis variables.
Between these accretion bursts, the protostar is characterized by a low
accretion rate (< 10^{-6} M_sun/yr). During the phase of episodic accretion,
the mass of the protostellar disk remains less than or comparable to the mass
of the protostar.


title: Turbulence and its parameterization in accretion discs

abstract:
  Accretion disc turbulence is investigated in the framework of the shearing
box approximation. The turbulence is either driven by the magneto-rotational
instability or, in the non-magnetic case, by an explicit and artificial forcing
term in the momentum equation. Unlike the magnetic case, where most of the
dissipation occurs in the disc corona, in the forced hydrodynamic case most of
the dissipation occurs near the midplane. In the hydrodynamic case evidence is
presented for the stochastic excitation of epicycles. When the vertical and
radial epicyclic frequencies are different (modeling the properties around
rotating black holes), the beat frequency between these two frequencies appear
to show up as a peak in the temporal power spectrum in some cases. Finally, the
full turbulent resistivity tensor is determined and it is found that, if the
turbulence is driven by a forcing term, the signs of its off-diagonal
components are such that this effect would not be capable of dynamo action by
the shear--current effect.


title: The Origin of Cosmic Rays

abstract:
  It is generally regarded that the bulk of cosmic rays originate in the Galaxy
and that those below the 'knee' (the rapid steepening in the energy spectrum)
at a few PeV come from Galactic supernovae, the particles being accelerated by
the shocks in the supernova remnants. At higher energies, there are problems in
that conventional SNR - which surely constitute the bulk of the sources - have
a natural limit at a few tens of PeV (for iron nuclei). The question of the
origin of particles above this limit is thus an open one. Here we examine a
number of possibilities: a variety of supernovae and hypernovae, pulsars, a
Giant Galactic Halo and an Extragalactic origin.
  A relevant property of any model is the extent to which it can provide the
lack of significant irregularity of the energy spectrum. Although it is
appreciated that spectral measurements are subject to systematic as well as
random errors we consider that contemporary data are good enough to allow at
least some progress in this field.
  In the search for origin above PeV energies we conclude that shocks in the
Galactic Halo, whatever their source (Galactic wind, relativistic plasmoids -
'cannonballs', multiple shocks from supernovae etc.) are most likely, pulsrs
such as B0656+14 and hypernovae come a close second although such a suggestion
is not without its difficulties. What is most important is that trapping of
particles in the Halo is needed to reduce irregularities of the energy spectra
both below and above the 'knee' caused by the stochastic nature of supernova
explosions and other potential (discrete) Galactic sources.
  We argue that precise experimental studies of spectral 'irregularities' will
provide considerable help in the search for cosmic ray origin.


title: Parametrization of dark energy equation of state Revisited

abstract:
  A comparative study of various parametrizations of the dark energy equation
of state is made. Astrophysical constraints from LSS, CMB and BBN are laid down
to test the physical viability and cosmological compatibility of these
parametrizations. A critical evaluation of the 4-index parametrizations reveals
that Hannestad-M\"{o}rtsell as well as Lee parametrizations are simple and
transparent in probing the evolution of the dark energy during the expansion
history of the universe and they satisfy the LSS, CMB and BBN constraints on
the dark energy density parameter for the best fit values.


title: Gamma Ray Bursts and the transition to Quark Matter in Compact Stars

abstract:
  We discuss a model for long Gamma-Ray-Bursts in which the central engine is
associated with the conversion process of a metastable hadronic star into a
star containing quark matter. We analyze the observational signatures of the
model, i.e. the Supernova-GRB temporal connection and the existence of long
quiescent times in the temporal structure of Gamma-Ray-Bursts.