title:
The XMM-Newton survey of the ELAIS-S1 field. I: Number counts, angular
  correlation function and X-ray spectral properties

abstract:
  We have surveyed with XMM-Newton the central ~0.6 deg2 region of the ELAIS-S1
field down to flux limits of ~5.5X10-16 cgs (0.5-2 keV, S band), ~2X10-15 cgs
(2-10 keV, H band), and ~4X10-15 cgs (5-10 keV, HH band). We detect a total of
478 sources, 395 and 205 of which detected in the S and H bands respectively.
We identified 7 clearly extended sources and estimated their redshift through
X-ray spectral fits with thermal models. In four cases the redshift is
consistent with z=0.4. We have computed the angular correlation function of the
sources in the S and H bands, finding best fit correlation angles
theta_0=5.2+/-3.8 arcsec and theta_0=12.8+/-7.8 arcsec respectively. A rough
estimate of the present-day correlation length r_0 can be obtained inverting
the Limber equation and assuming an appropriate redshift distribution dN/dz.
The results range between 12.8 and 9.8 h-1 Mpc in the S band and between 17.9
and 13.4 h-1 Mpc in the H band, with 30-40% statistical errors, assuming either
smooth redshift distributions or redshift distributions with spikes accounting
for the presence of a structure at z=0.4. The relative density of the S band
sources is higher near the clusters and groups at z~0.4 and extends toward East
and toward South/West. This suggests that the structure is complex, with a size
comparable to the full XMM-Newton field. Conversely, the highest relative
source densities of the H band sources are located in the central-west region
of the field.


title:
The highly obscured region around PKS1343-601 - I. Galactic interstellar
  extinctions using DENIS galaxy colours

abstract:
  The highly obscured radio-bright galaxy PKS1343-601 (l=309.7, b=+1.8) has
been suspected to mark the centre of a hitherto unknown cluster in the Great
Attractor region. As such it presents an ideal region for a search of galaxies
in the near-infrared (NIR) and an in-depth study of their colours as a function
of extinction. A visual search of a ~30 square-degree area centered on this
radio galaxy on images of the NIR DENIS survey (IJK) revealed 83 galaxies
(including two AGNs) and 39 possible candidates. Of these, 49 are also listed
in the 2MASS Extended Source Catalog 2MASX. Taking the IRAS/DIRBE extinction
values (Schlegel et al. 1998) at face value, the absorption in the optical
(A_B) ranges from ~2m to over 100m across the Galactic Plane. Comparing the
detections with other systematic surveys, we conclude that this search is
highly complete up to the detection limits of the DENIS survey and certainly
surpasses any automatic galaxy finding algorithm applied to crowded areas. The
NIR galaxy colours from the 7" aperture were used as a probe to measure total
Galactic extinction. A comparison with the IRAS/DIRBE Galactic reddening maps
suggests that the IRAS/DIRBE values result in a slight overestimate of the true
extinction at such low Galactic latitudes; the inferred extinction from the
galaxy colours corresponds to about 87% of the IRAS/DIRBE extinctions. Although
this determination still shows some scatter, it proves the usefulness of NIR
surveys for calibrating the IRAS/DIRBE maps in the extinction range of 2m < A_B
< 12m.


title: Cosmic Rays: Recent Progress and some Current Questions

abstract:
  Recent progress suggests we are moving towards a quantitative understanding
of the whole cosmic ray spectrum, and that many bumps due to different
components and processes hide beneath a relatively smooth total flux between
knee and ankle. The knee is much better understood: the KASCADE observations
support a rather sharp rigidity cut-off; while theoretical developments (strong
magnetic field generation) indicate that supernova remnants (SNR) of different
types should indeed accelerate to a very similar rigidity. X-ray and TeV
observations of shell-type SNR produce evidence in favour of acceleration at
their outer boundaries. There is some still-disputed evidence that the
transition to extragalactic cosmic rays has already occurred just above 10**17
eV, unmarked by an "ankle", in which case the whole spectrum can be well
described by adding a single power-law source spectrum from many extragalactic
sources (but modified by energy losses) to the SNR pre-knee component, if the
sources photodisintegrate all nuclei. At the highest energy, the experiments
using fluorscence light to calibrate energy do not yet show any conflict with
an expected GZK "termination". GRBs seem not to make a significant
contribution.


title:
Prompt and Afterglow Emission Properties of Gamma-Ray Bursts with
  Spectroscopically Identified Supernovae

abstract:
  We present a detailed spectral analysis of the prompt and afterglow emission
of four nearby long-soft gamma-ray bursts (GRBs 980425, 030329, 031203, and
060218) that were spectroscopically found to be associated with type Ic
supernovae, and compare them to the general GRB population. For each event, we
investigate the spectral and luminosity evolution, and estimate the total
energy budget based upon broadband observations. The observational inventory
for these events has become rich enough to allow estimates of their energy
content in relativistic and sub-relativistic form. The result is a global
portrait of the effects of the physical processes responsible for producing
long-soft GRBs. In particular, we find that the values of the energy released
in mildly relativistic outflows appears to have a significantly smaller scatter
than those found in highly relativistic ejecta. This is consistent with a
picture in which the energy released inside the progenitor star is roughly
standard, while the fraction of that energy that ends up in highly relativistic
ejecta outside the star can vary dramatically between different events.


title:
ATCA observations of the galaxy cluster Abell 3921 - I. Radio emission
  from the central merging sub-clusters

abstract:
  We present the analysis of our 13 and 22 cm ATCA observations of the central
region of the merging galaxy cluster A3921 (z=0.094). We investigated the
effects of the major merger between two sub-clusters on the star formation (SF)
and radio emission properties of the confirmed cluster members. The origin of
SF and the nature of radio emission in cluster galaxies was investigated by
comparing their radio, optical and X-ray properties. We also compared the radio
source counts and the percentage of detected radio galaxies with literature
data. We detected 17 radio sources above the flux density limit of 0.25
mJy/beam in the central field of A3921, among which 7 are cluster members. 9
galaxies with star-forming optical spectra were observed in the collision
region of the merging sub-clusters. They were not detected at radio
wavelengths, giving upper limits for their star formation rate significantly
lower than those typically found in late-type, field galaxies. Most of these
star-forming objects are therefore really located in the high density part of
the cluster, and they are not infalling field objects seen in projection at the
cluster centre. Their SF episode is probably related to the cluster collision
that we observe in its very central phase. None of the galaxies with
post-starburst optical spectra was detected down our 2$\sigma$ flux density
limit, confirming that they are post-starburst and not dusty star-forming
objects. We finally detected a narrow-angle tail (NAT) source associated with
the second brightest cluster galaxy (BG2), whose diffuse component is a partly
detached pair of tails from an earlier period of activity of the BG2 galaxy.


title:
The Thermal Regulation of Gravitational Instabilities in Protoplanetary
  Disks III. Simulations with Radiative Cooling and Realistic Opacities

abstract:
  This paper presents a fully three-dimensional radiative hydrodymanics
simulation with realistic opacities for a gravitationally unstable 0.07 Msun
disk around a 0.5 Msun star. We address the following aspects of disk
evolution: the strength of gravitational instabilities under realistic cooling,
mass transport in the disk that arises from GIs, comparisons between the
gravitational and Reynolds stresses measured in the disk and those expected in
an alpha-disk, and comparisons between the SED derived for the disk and SEDs
derived from observationally determined parameters. The mass transport in this
disk is dominated by global modes, and the cooling times are too long to permit
fragmentation for all radii. Moreover, our results suggest a plausible
explanation for the FU Ori outburst phenomenon.


title: Enrichment in the Centaurus cluster of galaxies

abstract:
  We perform a detailed spatially-resolved, spectroscopic, analysis of the core
of the Centaurus cluster of galaxies using a deep Chandra X-ray observation and
XMM-Newton data. The Centaurus cluster core has particularly high metallicity,
upto twice Solar values, and we measure the abundances of Fe, O, Ne, Mg, Si, S,
Ar, Ca and Ni. We map the distribution of these elements in many spatial
regions,and create radial profiles to the east and west of the centre. The
ratios of the most robustly determined elements to iron are consistent with
Solar ratios, indicating that there has been enrichment by both Type Ia and
Type II supernovae. For a normal initial stellar mass function it represents
the products of about 4x10^10 solar masses of star formation. This star
formation can have occured either continuously at a rate of 5 solar masses per
year for the past 8 Gyr or more,or was part of the formation of the central
galaxy at earlier times. Either conclusion requires that the inner core of the
Centaurus cluster has not suffered a major disruption within the past 8 Gyr, or
even longer.


title:
The abundances of nitrogen-containing molecules during pre-protostellar
  collapse

abstract:
  We have studied the chemistry of nitrogen--bearing species during the initial
stages of protostellar collapse, with a view to explaining the observed
longevity of N2H+ and NH3 and the high levels of deuteration of these species.
We followed the chemical evolution of a medium comprising gas and dust as it
underwent free--fall gravitational collapse. Chemical processes which determine
the relative populations of the nuclear spin states of molecules and molecular
ions were included explicitly, as were reactions which lead ultimately to the
deuteration of the nitrogen--containing species N2H+ and NH3. The freeze-out of
`heavy' molecules onto grains was taken into account. We found that the
timescale required for the nitrogen--containing species to attain their
steady--state values was much larger than the free--fall time and even
comparable with the probable lifetime of the precursor molecular cloud.
However, it transpires that the chemical evolution of the gas during
gravitational collapse is insensitive to its initial composition. If we suppose
that the grain--sticking probabilities of atomic nitrogen and oxygen are both
less than unity (S less than 0.3), we find that the observed differential
freeze--out of nitrogen- and carbon--bearing species can be reproduced by the
model of free--fall collapse when a sufficiently large grain radius (a_{g}= 0.5
micron) is adopted. Furthermore, the results of our collapse model are
consistent with the high levels of deuteration of N2H+ and NH3 which have been
observed in L1544 providing that 0.5<a_{g}<1 micron. We note that the o/p H2D+
ratio and fractional abundance of ortho-H2D+ should be largest when ND3 is most
abundant.


title:
Enhancing the Pierre Auger Observatory to the 10^{17} to 10^{18.5} eV
  Range: Capabilities of an Infill Surface Array

abstract:
  The Pierre Auger Observatory has been designed to study the highest-energy
cosmic rays in nature (E > 10^{18.5} eV). The determination of their arrival
direction, energy and composition is performed by the analysis of the
atmospheric showers they produce. The Auger Surface Array will consist of 1600
water Cerenkov detectors placed in an equilateral triangular grid of 1.5 km
spacing. The aim of this paper is to show that the addition of a "small" area
of surface detectors at half or less the above mentioned spacing would allow a
dramatic increase of the physical scope of this Observatory, reaching lower
energies at which the transition from galactic to extragalactic sources is
expected.


title:
Subarcsecond Resolution Mid-Infrared Observations of Super Star Clusters
  in the Antennae (NGC4038/4039)

abstract:
  In this letter we present ground-based subarcsecond mid-infrared imaging and
spectroscopy of young super star clusters in the overlap region of the merging
galaxies NGC4038/4039 (the Antennae) obtained with the VLT Imager and
Spectrometer for mid-Infrared (VISIR). With its unprecedented spatial
resolution VISIR begins to resolve the HII/PDR complexes around the
star-forming regions for the first time. In the N-band spectra of two young
star clusters unexpectedly low polycyclic aromatic hydrocarbon (PAH) emission
is observed, compared to what is seen with the Infrared Space Observatory (ISO)
and with the Spitzer Space Telescope. We conclude that a large fraction of the
PAH emission cannot directly be associated with the super star clusters, but
originate from an extended region of at least 215 pc radius around the
clusters. In the distribution of [NeII] 12.81 micron emission a highly obscured
cluster is discovered that does not have an optical or near-infrared
counterpart.


title:
The luminosities, sizes and velocity dispersions of Brightest Cluster
  Galaxies: Implications for formation history

abstract:
  The size-luminosity relation of early-type Brightest Cluster Galaxies (BCGs),
R_e ~ L^0.88, is steeper than that for the bulk of the early-type galaxy
population, for which R_e ~ L^0.68. In addition, although BCGs are hardly
offset from the Fundamental Plane defined by the bulk of the early-type
population, they show considerably smaller scatter. The larger than expected
sizes of BCGs, and the increased homogeneity, are qualitatively consistent with
models which seek to explain the colors of the most massive galaxies by
invoking dry dissipationless mergers, since dissipation tends to reduce the
sizes of galaxies, and wet mergers which result in star formation would tend to
increase the scatter in luminosity at fixed size and velocity dispersion.
Furthermore, BCGs define the same g-r color-magnitude relation as the bulk of
the early-type population. If BCGs formed from dry mergers, then BCG
progenitors must have been red for their magnitudes, suggesting that they
hosted older stellar populations than typical for their luminosities. Our
findings have two other consequences. First, the R_e-L relation of the
early-type galaxy population as a whole (i.e., normal plus BCG) exhibits some
curvature. Some of this curvature must be a consequence of the fact that an
increasing fraction of the most luminous galaxies are BCGs. The second
consequence is suggested by the fact that, despite following a steeper
size-luminosity relation, BCGs tend to define a tight relation between
dynamical mass R_e sigma^2/G and luminosity. As consequence, we find that BCGs
define a shallower sigma-L relation than the bulk of the early-type galaxy
population.


title: The Burst Mode of Protostellar Accretion

abstract:
  We present new numerical simulations in the thin-disk approximation which
characterize the burst mode of protostellar accretion. The burst mode begins
upon the formation of a centrifugally balanced disk around a newly formed
protostar. It is comprised of prolonged quiescent periods of low accretion rate
(typically $\la 10^{-7} \Msun$ yr$^{-1}$) which are punctuated by intense
bursts of accretion (typically $\ga 10^{-4} \Msun$ yr$^{-1}$, with duration
$\la 100$ yr) during which most of the protostellar mass is accumulated. The
accretion bursts are associated with the formation of dense
protostellar/protoplanetary embryos, which are later driven onto the protostar
by the gravitational torques that develop in the disk. Gravitational
instability in the disk, driven by continuing infall from the envelope, is
shown to be an effective means of transporting angular momentum outward, and
mass inward to the protostar. We show that the disk mass always remains
significantly less than the central protostar mass throughout this process. The
burst phenomenon is robust enough to occur for a variety of initial values of
rotation rate, frozen-in (supercritical) magnetic field, and
density-temperature relations. Even in cases where the bursts are nearly
entirely suppressed, a moderate increase in cloud size or rotation rate can
lead to vigorous burst activity. We conclude that most (if not all) protostars
undergo a burst mode of evolution during their early accretion history, as
inferred empirically from observations of FU Orionis variables.


title:
Empirical relation between angular momentum transport and
  thermal-to-magnetic pressure ratio in shearing box simulations

abstract:
  By combining data from different published 3-D simulations of Keplerian
shearing boxes unstable to the magnetorotational instability (MRI), we
highlight tight anti-correlations between the total effective inferred angular
momentum transport parameter, $\alpha_{tot}$, its separate Maxwell and Reynolds
contributions $\alpha_{mag}$ and $\alpha_{kin}$, and the kinetic to magnetic
pressure ratio $\beta$, defined with the initial or saturated (when available)
thermal pressure.
  Plots of $Log (\alpha_{kin}), Log (\alpha_{mag})$, and $Log (\alpha_{tot})$
vs $Log (\beta)$ are well fit by straight lines even as $\alpha_{kin}$,
$\alpha_{mag}$,and $\alpha_{tot}$ vary by four orders of magnitude over the
simulations included. The ratio $\alpha_{kin}/\alpha_{mag}$ and the product
$\alpha_{tot}\beta$ are quite constant and largely independent of the presence
or absence of weak mean fields, the choice of initial and boundary conditions,
and the resolution. In short, simulations have more strongly constrained the
product $\alpha_{tot}\beta$ than $\alpha_{tot}$ itself.


title:
Angular Diameter Distance Measurement with Galaxy Clustering in the
  Multipole Space

abstract:
  The shape of the angular power spectrum of galaxies in the linear regime is
defined by the horizon size at the matter-radiation equality. When calibrated
by cosmic microwave background measurements, the shape of the clustering
spectrum can be used as a standard ruler to estimate angular diameter distance
as a function of redshift at which galaxy clustering is measured. We apply the
proposed cosmological test of Cooray et al. (2001) to a recent set of luminous
red galaxy angular clustering spectra from the Sloan Digital Sky Survey between
redshifts of 0.2 and 0.6. Using the overall shape of the clustering power
spectrum in the linear regime, w e measure comoving angular diameter distances
to eight redshift bins by marginalizing over the bias factors that determine
the overall amplitude of the clustering spectrum in each of the bins. The
Hubble constant consistent with these distance estimates is 68.5^+6.7_-6.1 km
s^-1 Mpc-1 at the 68% confidence level. We comment on the expected improvements
with future surveys and the potential to measure dark energy parameters with
this method.


title: Annual Modulation of Dark Matter in the Presence of Streams

abstract:
  In addition to a smooth component of WIMP dark matter in galaxies, there may
be streams of material; the effects of WIMP streams on direct detection
experiments is examined in this paper. The contribution to the count rate due
to the stream cuts off at some characteristic energy. Near this cutoff energy,
the stream contribution to the annual modulation of recoils in the detector is
comparable to that of the thermalized halo, even if the stream represents only
a small portion (~5% or less) of the local halo density. Consequently the total
modulation may be quite different than would be expected for the standard halo
model alone: it may not be cosine-like and can peak at a different date than
expected. The effects of speed, direction, density, and velocity dispersion of
a stream on the modulation are examined. We describe how the observation of a
modulation can be used to determine these stream parameters. Alternatively, the
presence of a dropoff in the recoil spectrum can be used to determine the WIMP
mass if the stream speed is known. The annual modulation of the cutoff energy
together with the annual modulation of the overall signal provide a "smoking
gun" for WIMP detection.


title:
Dark energy and curvature from a future baryonic acoustic oscillation
  survey using the Lyman-alpha forest

abstract:
  We explore the requirements for a Lyman-alpha forest (LyaF) survey designed
to measure the angular diameter distance and Hubble parameter at 2~<z~<4 using
the standard ruler provided by baryonic acoustic oscillations (BAO). The goal
would be to obtain a high enough density of sources to probe the
three-dimensional density field on the scale of the BAO feature. A
percent-level measurement in this redshift range can almost double the Dark
Energy Task Force Figure of Merit, relative to the case with only a similar
precision measurement at z~1, if the Universe is not assumed to be flat. This
improvement is greater than the one obtained by doubling the size of the z~1
survey, with Planck and a weak SDSS-like z=0.3 BAO measurement assumed in each
case. Galaxy BAO surveys at z~1 may be able to make an effective LyaF
measurement simultaneously at minimal added cost, because the required number
density of quasars is relatively small. We discuss the constraining power as a
function of area, magnitude limit (density of quasars), resolution, and
signal-to-noise of the spectra. For example, a survey covering 2000 sq. deg.
and achieving S/N=1.8 per Ang. at g=23 (~40 quasars per sq. deg.) with an
R~>250 spectrograph is sufficient to measure both the radial and transverse
oscillation scales to 1.4% from the LyaF (or better, if fainter magnitudes and
possibly Lyman-break galaxies can be used). At fixed integration time and in
the sky-noise-dominated limit, a wider, noisier survey is generally more
efficient; the only fundamental upper limit on noise being the need to identify
a quasar and find a redshift. Because the LyaF is much closer to linear and
generally better understood than galaxies, systematic errors are even less
likely to be a problem.


title: Accretion models of Sgr A*

abstract:
  The supermassive black hole in the center of our Galaxy, Sgr A*, is unique
because the angular size of the black hole is the largest in the sky thus
providing detailed boundary conditions on, and much less freedom for, accretion
flow models. In this paper I review advection-dominated accretion flow (ADAF;
another name is radiatively inefficient accretion flow) models for Sgr A*. This
includes the developments and dynamics of ADAFs, and how to explain
observational results including the multi-waveband spectrum, radio
polarization, IR and X-ray flares, and the size measurements at radio
wavebands.


title: Propeller driven spectral state transition in LMXB 4U 1608-52

abstract:
  Spectral state transitions in neutron star LMXB systems have been widely
observed yet not well understood. Here we report an abrupt spectral change in
4U 1608-52, a typical atoll source, during its decay phase of the 2004
outburst. The source is found to undergo sudden changes in its spectral
hardness and other properties. The transition occurred when its luminosity is
between (3.3-5.3) E36 ergs/s, assuming a distance of 3.6 kpc. Interpreting this
event in terms of the propeller effect, we infer the neutron star surface
magnetic field as (1.4-1.8) E8 Gauss. We also briefly discuss similarities and
differences between the spectral states of neutron star and black hole binary
systems.


title: Multi-Object Spectroscopy Field Configuration by Simulated Annealing

abstract:
  Multi-object spectroscopy (MOS) instruments, such as the Two-degree Field
(2dF) facility of the Anglo-Australian Observatory (AAO), have facilitated
large-scale redshift surveys. Yet despite their acclaim, instrument design has
been suspected of introducing subtle selection effects into surveys.
Investigation into these selection effects has been overshadowed by instrument
complexity. We identify the field configuration algorithm (FCA) used to select
targets for observation as mainly responsible for such effects. A FCA can
imprint artificial structure on observed target distributions, which may accrue
over large angular scales, potentially to the detriment of statistical analyses
applied to such surveys. We present here a new FCA developed for 2dF that is
based on simulated annealing (SA), a generic method commonly used to solve
constrained optimisation problems. We generate synthetic fields and utilise
mock 2dF volumes to contrast the behaviour of previous strategies with the SA
FCA. The angular two-point correlation function and other sensitive techniques
reveal that the new FCA achieves unprecedented sampling uniformity and target
yield with improved target priority handling and observational flexibility over
current FCAs. The SA FCA is generic enough to be used by current 2dF-like and
potentially next-generation MOS instruments with little modification.


title:
Interacting Dark Energy and Dark Matter: observational Constraints from
  Cosmological Parameters

abstract:
  Several observational constraints are imposed on the interacting holographic
model of Dark Energy and Dark Matter. First we use the age parameter today, as
given by the WMAP results. Subsequently, we explained the reason why it is
possible, as recently observed, for an old quasar to be observed in early
stages of the universe. We discuss this question in terms of the evolution of
the age parameter as well as in terms of the structure formation. Finally, we
give a detailed discussion of the constraints implied by the observed CMB low
$\ell$ suppression. As a result, the interacting holographic model has been
proved to be robust and with reasonable bounds predicts a non vanishing
interaction of Dark Energy and Dark Matter.


title: DIOS: the Diffuse Intergalactic Oxygen Surveyor

abstract:
  We present our proposal for a small X-ray mission DIOS (Diffuse Intergalactic
Oxygen Surveyor), consisting of a 4-stage X-ray telescope and an array of TES
microcalorimeters, cooled with mechanical coolers, with a total weight of about
400 kg. The mission will perform survey observations of warm-hot intergalactic
medium using OVII and OVIII emission lines, with the energy coverage up to 1.5
keV. The wide field of view of about 50' diameter, superior energy resolution
close to 2 eV FWHM, and very low background will together enable us a wide
range of science for diffuse X-ray sources. We briefly describe the design of
the satellite, performance of the subsystems and the expected results.


title: Many binaries among NEAs

abstract:
  The number of binary asteroids in the near-Earth region might be
significantly higher than expected. While Bottke and Melosh (1996) suggested
that about 15% of the NEAs are binaries, as indicated from the frequency of
double craters, and Pravec and Harris (2000) suggested that half of the
fast-rotating NEAs are binaries, our recent study of Aten NEA lightcurves shows
that the fraction of binary NEAs might be even higher than 50%. We found two
asteroids with asynchronous binary characteristics such as two additive periods
and fast rotation of the primary fragment. We also identified three asteroids
with synchronous binary characteristics such as amplitude higher than one
magnitude, U-shaped lightcurve maxima and V-shaped lightcurve minima. These
five binaries were detected out of a sample of eight asteroids observed,
implying a 63% binarity frequency. Confirmation of this high binary population
requires the study of a larger representative sample. However, any mitigation
program that requires the deflection or demise of a potential impactor will
have to factor in the possibility that the target is a binary or multiple
asteroid system.


title: Diffuse Interstellar Bands and Their Families

abstract:
  Diffuse interstellar bands (DIBs) still await an explanation. One expects
that some progress in this field will be possible when all the known DIBs are
divided into families in such a way that only one carrier is responsible for
all bands belonging to the given family. Analysing high resolution optical
spectra of reddened stars we try to find out spectroscopic families for two
prominent DIBs, at 5780 and 5797 angstroms. Among the DIBs, observed in the
spectral range from 5590 to 6830 angstroms, we have found 8 candidates to
belong to 5780 spectroscopic family and the other 12 DIBs candidating to family
of 5797 structure.


title: Cosmological applications of the Szekeres model

abstract:
  This paper presents the cosmological applications of the quasispherical
Szekeres model. The quasispherical Szekeres model is an exact solution of the
Einstein field equations, which represents a time-dependent mass dipole
superposed on a monopole and therefore is suitable for modelling double
structures such as voids and adjourning galaxy superclusters. Moreover, as the
Szekeres model is an exact solution of the Einstein equations it enables
tracing light and estimation of the impact of cosmic structures on light
propagation. This paper presents the evolution of a void and adjourning
supercluster and also reports on how the Szekeres model might be employed
either for the estimation of mass of galaxies clusters or for the estimation of
the luminosity distance.


title: Hot-dark matter, cold dark matter and accelerating universe

abstract:
  The Friedman equation is solved for a universe contains hotdark matter and
cold dark matter. In this scenario, hot-dark matter drives an accelerating
universe no cold dark matter.


title:
Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region;
  I. Dispersing and Rotating Core around an Intermediate-mass Protostar MMS 7

abstract:
  We report the results of H13CO+(1-0), CO(1-0), and 3.3 mm dust continuum
observations toward one of the strongest mm-wave sources in OMC-3, MMS 7, with
the Nobeyama Millimeter Array (NMA) and the Nobeyama 45 m telescope. With the
NMA, we detected centrally-condensed 3.3 mm dust-continuum emission which
coincides with the MIR source and the free-free jet. Our combined H13CO+
observations have revealed a disk-like envelope. The size and the mass of the
disk-like envelope are 0.15 times 0.11 pc and 5.1 - 9.1 M_sun, respectively.
The combined map also shows that the outer portion of the disk-like envelope
has a fan-shaped structure which delineates the rim of the CO(1-0) outflow
observed with the NMA. The position-velocity (P-V) diagrams in the H13CO+ (1-0)
emission show that the velocity field in the disk-like envelope is composed of
a dispersing gas motion and a possible rigid-like rotation. The mass dispersing
rate is estimated to be (3.4 - 6.0) times 10^-5 M_sun/yr, which implies that
MMS 7 has an ability to disperse ~10 M_sun during the protostellar evolutional
time of a few times 10^5 yr. The specific angular momentum of the possible
rotation in the disk-like envelope is nearly two orders of magnitude larger
than that in low-mass cores. The turn-over point of the power law of the
angular momentum distribution in the disk-like envelope (< 0.007 pc), which is
likely to be related to the outer radius of the central mass accretion, is
similar to the size of the 3.3 mm dust condensation. The intermediate-mass
protostar MMS 7 is in the last stage of the main accretion phase and that the
substantial portion of the outer gas has already been dispersed, while the mass
accretion may still be on-going at the innermost region traced by the dusty
condensation.


title: Microlensing variability in time-delay quasars

abstract:
  We have searched for microlensing variability in the light curves of five
gravitationally lensed quasars with well-determined time delays: SBS 1520+530,
FBQ 0951+2635, RX J0911+0551, B1600+434 and HE 2149-2745. By comparing the
light curve of the leading image with a suitably time offset light curve of a
trailing image we find that two (SBS 1520+530 and FBQ 0951+2635) out of the
five quasars have significant long-term (years) and short-term (100 days)
brightness variations that may be attributed to microlensing.The short-term
variations may be due to nanolenses, relativistic hot or cold spots in the
quasar accretion disks, or coherent microlensing at large optical depth.


title:
The Optical Gravitational Lensing Experiment. Variable Baseline
  Microlensing Events in the Galactic Bulge

abstract:
  We present the first systematic search for microlensing events with
variability in their baselines using data from the third phase of the Optical
Gravitational Lensing Experiment (OGLE-III). A total of 137 candidates (88 new)
was discovered toward the Galactic bulge. Among these, 21 have periodic
oscillations in their baselines, 111 are irregular variables and 5 are
potential long period detached eclipsing binaries. This is about 10% of the
total number of constant baseline events. They are hence quite common and can
be regarded as a new type of exotic events, which allow the determination of
extra parameters of the events. We show that microlensing of variable stars may
allow us to break the degeneracy between the blending parameter and
magnification. We note that in some cases variability hidden in the baseline
due to strong blending may be revealed in highly magnified events and resemble
other exotic microlensing behavior, including planetary deviation. A new system
(VEWS) for detecting ongoing variable baseline microlensing events is
presented.


title:
The XMM Large Scale Structure Survey: Properties and Two-Point Angular
  Correlations of Point-like Sources

abstract:
  We analyze X-ray sources detected over 4.2 pseudo-contiguous sq. deg. in the
0.5-2 keV and 2-10 keV bands down to fluxes of 2x10^{-15} and 8x10^{-15}
erg/s/cm^2 respectively, as part of the XMM Large Scale Structure Survey. The
logN-logS in both bands shows a steep slope at bright fluxes, but agrees well
with other determinations below ~2x10^{-14} erg/s/cm^2. The detected sources
resolve close to 30 per cent of the X-ray background in the 2-10 keV band. We
study the two-point angular clustering of point sources using nearest
neighbours and correlation function statistics and find a weak, positive signal
for ~1130 sources in the 0.5-2 keV band, but no correlation for ~400 sources in
the 2-10 keV band below scales of 100 arcsec. A sub-sample of ~200 faint
sources with hard X-ray count ratios, that is likely to be dominated by
obscured AGN, does show a positive signal with the data allowing for a large
scaling of the angular correlation length, but only at the ~2 (3) sigma level,
based on re-sampling (Poisson) statistics. We discuss possible implications and
emphasize the importance of wider, complete surveys in order to fully
understand the large scale structure of the X-ray sky.


title:
Precise Radial Velocities of Giant Stars II. Pollux and its Planetary
  Companion

abstract:
  It has long been speculated that the observed periodic radial velocity
pattern for the K giant Pollux might be explained in terms of an orbiting
planetary companion. We have collected 80 high-resolution spectra for Pollux at
Lick Observatory yielding precise radial velocities with a mean error of 3.8
m/s, providing the most comprehensive and precise data set available for this
star. Our data confirm the periodicity previously seen in the radial
velocities. We derive a period of 589.7+/-3.5 days and, assuming a primary mass
of 1.86 M_Sun, a minimum companion mass of 2.9+/-0.3 M_Jup, consistent with
earlier determinations. No evidence for any periodicities is visible in our
analysis of the shapes of the spectral lines via the bisector method, so that
we conclude that evidence is accumulating and compelling for a planet around
Pollux. However, some last doubt remains about this interpretation, because
non-radial pulsations which might be present in giant stars could in principle
also explain the observed radial velocities, while the accompanying bisector
variations might be too small to be detectable with current data.


title: HI Absorption in High-Frequency Peaker Galaxies

abstract:
  WSRT observations have been used to investigate the presence of neutral
hydrogen in extremely young radio galaxies. These objects were selected from a
sample of High-Frequency Peakers (HFPs). We detect 2 of the 6 observed galaxies
confirming previous detection of HI in these objects. In the case of OQ 208 -
for which discrepant results were available - we confirm the presence of a
broad (~ 1800 km/s), blue-shifted and shallow HI absorption. No significant
changes in the HI profile have been found between the two epochs of the
observations. The intriguing result is that the derived HI column densities and
upper limits obtained for the most compact sources, do not follow the inverse
correlation between the column density and the linear size found for CSS/GPS
sources. This can be explained - assuming the gas is already in a torus/disk
structure - by a combination of the orientation and the extreme compactness of
the sources. In this scenario, our line of sight to the source would intersect
the torus in its inner region with low optical depth due to high spin and
kinetic temperatures. There is no evidence, with the exception of OQ 208, of
unsettled, high column density gas still enshrouding the young radio sources.
This can be due to the low filling factor of such a medium.


title:
Multiwavelength Observations of the BL Lacertae Object PKS 2155-304 with
  XMM-Newton

abstract:
  The optical-UV and X-ray instruments on-board XMM-Ndewton provide an
excellent opportunity to perform simultaneous observations of violently
variable objects over a broad wavelength range. The UV and X-ray bright BL Lac
object PKS 2155-304 has been repeatedly observed with XMM-Ndewton about twice
per year. In this paper, we present a detailed analysis of the simultaneous
multiwavelength variability of the source from optical to X-rays, based on the
currently available XMM-Ndewton observations. These observations probed the
intra-day multiwavelength variability at optical-UV and X-ray wavelengths of
the source. The UV variability amplitude is substantially smaller than the
X-ray one, and the hardness ratios of the UV to X-rays correlates with the
X-ray fluxes: the brighter the source, the flatter the UV-X-ray spectra. On
2000 May 30-31 the UV and X-ray light curves were weakly correlated, while the
UV variations followed the X-ray ones with no detectable lags on 2000 November
19-21. On 2001 November 30 the source exhibited a major X-ray flare that was
not detected in the optical. The intra-day UV and X-ray variability presented
here is not similar to the inter-day UV and X-ray variability obtained from the
previous coordinated extensive multiwavelength campaigns on the source,
indicating that different ``modes'' of variability might be operating in PKS
2155-304 on different timescales or from epoch to epoch.


title:
Angular distribution of satellite galaxies from the Sloan Digital Sky
  Survey Data Release 4

abstract:
  We explore the angular distribution of two samples of satellite galaxies
orbiting isolated hosts extracted from the Sloan Digital Sky Survey Data
Release 4. We find a clear alignment of the satellites along the major axis of
their hosts when restricting the analysis to red hosts. The anisotropy is most
pronounced for red satellites of red hosts. We find that the distribution of
the satellites about blue, isolated hosts is consistent with isotropy. We show
that under the assumption that the true, underlying distribution of satellites
of blue hosts exhibits the same anisotropy as the satellites of red hosts, the
sample of blue hosts is too small to measure this anisotropy at a
statistically-significant level. The anisotropy that we detect for satellites
about red primaries is independent of the projected radius. In particular, it
is evident at large projected distances from primaries (300 < r_p < 500 kpc).


title:
Mass Determination and Detection of the Onset of Chromospheric Activity
  for the Sub-Stellar Object in EF Eridani

abstract:
  EF Eri is a magnetic cataclysmic variable that has been in a low accretion
state for the past nine years. Low state optical spectra reveal the underlying
Zeeman-split white dwarf absorption lines. These features are used to determine
a value of 13-14 MG as the white dwarf field strength. Recently, 5-7 years into
the low state, Balmer and other emission lines have appeared in the optical. An
analysis of the H$\alpha$ emission line yields the first radial velocity
solution for EF Eri, leading to a spectroscopic ephemeris for the binary and,
using the best available white dwarf mass of 0.6M${\odot}$, a mass estimate for
the secondary of 0.055M${\odot}$. For a white dwarf mass of 0.95M${\odot}$, the
average for magnetic white dwarfs, the secondary mass increases to
0.087M${\odot}$. At EF Eri's orbital period of 81 minutes, this higher mass
secondary could not be a normal star and still fit within the Roche lobe. The
source of the Balmer and other emission lines is confirmed to be from the
sub-stellar secondary and we argue that it is due to stellar activity. We
compare EF Eri's emission line spectrum and activity behavior to that recently
observed in AM Her and VV Pup and attributed to stellar activity. We explore
observations and models originally developed for V471 Tau, for the RS CVn
binaries, and for extra-solar planets. We conclude that irradiation of the
secondary in EF Eri and similar systems is unlikely and, in polars, the
magnetic field interaction between the two stars (with a possible tidal
component) is a probable mechanism which would concentrate chromospheric
activity on the secondary near the sub-stellar point of the white dwarf.


title:
The ATESP 5 GHz radio survey I. Source counts and spectral index
  properties of the faint radio population

abstract:
  [Abridged] The nature and evolutionary properties of the faint radio
population, responsible for the steepening observed in the 1.4 GHz source
counts below 1 milliJy, are not yet entirely clear. Radio spectral indices may
help to constrain the origin of the radio emission in such faint radio sources
and may be fundamental in understanding eventual links to the optical light. We
study the spectral index behaviour of sources that were found in the 1.4 GHz
ATESP survey (Prandoni et al. 2000a,b). Using the Australia Telescope Compact
Array we observed at 5 GHz part of the region covered by the sub-mJy ATESP
survey. In particular we imaged a one square degree area for which deep optical
imaging in UBVRIJK is available. In this paper we present the 5 GHz survey and
source catalogue, we derive the 5 GHz source counts and we discuss the 1.4-5
GHz spectral index properties of the ATESP sources. The analysis of the optical
properties of the sample will be the subject of a following paper. The 5 GHz
survey has produced a catalogue of 111 radio sources, complete down to a (6
sigma) limit S_lim(5 GHz)~0.4 mJy. We take advantage of the better spatial
resolution at 5 GHz (~2 arcsec compared to ~8 arcsec at 1.4 GHz) to infer radio
source structures and sizes. The 5 GHz source counts derived by the present
sample are consistent with those reported in the literature, but improve
significantly the statistics in the flux range 0.4< S(5 GHz)<1 mJy. The ATESP
sources show a flattening of the 1.4-5 GHz spectral index with decreasing flux
density, which is particularly significant for the 5 GHz selected sample. Such
a flattening confirm previous results coming from smaller samples and is
consistent with a flattening of the 5 GHz source counts occurring at fluxes
<=0.5 mJy.


title: The mass missing problem in clusters: dark matter or modified dynamics?

abstract:
  The widely accepted dark matter hypothesis offers a seductive solution to
missing mass problems (galaxies, clusters of galaxies, gravitational collapse
in structure formation,...). However the physical nature of the Dark Matter
itself is still unknown. Alternatively, it has been proposed that apparent
dynamical evidence of dark matter is due to a modification of Newtons's law of
gravitation. Here we revisit the Modified Newtonian Dynamics (MOND) theories at
the scale of galaxy clusters. Using hydrodynamical simulations, we derived
quantities such as the density and the temperature of the ICM. We compared
those MOND simulated predictions to high quality X-ray density and temperature
profiles observed down to ~0.5 the virial radius. If the density profiles seems
in acceptable agreement, the simulated temperature show a constant increase
with the radius whereas the observed profiles show a flat to a mild decrease
shape down to ~0.5 Rvirial . We also computed the dynamical MOND mass for 8
X-ray clusters observed with XMM-Newton. If the MOND mass helps to lower the
discrepancy with the baryonic mass by ~20%, still ~80% of the mass in clusters
is unaccounted by baryons. In order to solve this problem and to reconcile MOND
with clusters observations, we investigated the possibility of an added dark
baryonic component. We assumed a component of massive neutrinos to fill the
remaining discrepancy between the observed MOND dynamical mass and the baryonic
mass. This led us to derive a tied observational lower limit for the neutrino
mass, m_nu > 1.06 eV.


title:
Evidence for strong evolution of the cosmic star formation density at
  high redshift

abstract:
  Deep HST/ACS and VLT/ISAAC data of the GOODS-South field were used to look
for high-redshift galaxies in the rest-frame UV wavelength range and to study
the evolution of the cosmic star-formation density at z~7. The GOODS-South area
was surveyed down to a limiting magnitude of about (J+Ks)=25.5 looking for
drop-out objects in the z ACS filter. The large sampled area would allow for
the detection of galaxies which are 20 times less numerous and 1-2 magnitudes
brighter than similar studies using HST/NICMOS near-IR data. Two objects were
initially selected as promising candidates of galaxies at z~7, but have
subsequently been dismissed and identified as Galactic brown dwarfs through a
detailed analysis of their morphology and Spitzer colors, as well as through
spectroscopic information. As a consequence, we conclude that there are no
galaxies at z~7 down to our limiting magnitude in the field we investigated.
Our non detection of galaxies at z~7 provides clear evidence for a strong
evolution of the luminosity function between z=6 and z=7, i.e. over a time
interval of only ~170 Myr. Our constraints also provide evidence for a
significant decline of the total star formation rate at z=7, which must be less
than 40% of that at z=3 and 40-80% of that at z=6. We also derive an upper
limit to the ionizing flux at z=7, which is only marginally consistent with
that required to completely ionize the Universe.


title:
Suzaku Reveals Helium-burning Products in the X-ray Emitting Planetary
  Nebula BD+303639

abstract:
  BD+303639, the brightest planetary nebula at X-ray energies, was observed
with Suzaku, an X-ray observatory launched on 2005 July 10. Using the X-ray
Imaging Spectrometer, the K-lines from C VI, O VII, and O VIII were resolved
for the first time, and C/O, N/O, and Ne/O abundance ratios determined. The C/O
and Ne/O abundance ratios exceed the solar value by a factor of at least 30 and
5, respectively. These results indicate that the X-rays are emitted mainly by
helium shell-burning products.


title: Neutrino-Cooled Accretion Disks around Spinning Black Hole

abstract:
  We calculate the structure of accretion disks around Kerr black holes for
accretion rates 0.001 - 10 M_sun/s. Such disks are plausible candidates for the
central engine of gamma-ray bursts. Our disk model is fully relativistic and
treats accurately microphysics of the accreting matter: neutrino emissivity,
opacity, electron degeneracy, and nuclear composition. The neutrino-cooled disk
forms above a critical accretion rate that depends on the black hole spin. The
disk has the ``ignition'' radius r_ign where neutrino flux rises dramatically,
cooling becomes efficient, and the proton-to-nucleon ratio Y_e drops. Other
characteristic radii are r_alpha where most of alpha-particles are
disintegrated, r_nu where the disk becomes neutrino-opaque, and r_trap where
neutrinos get trapped and advected into the black hole. We find r_alpha, r_ign,
r_nu, r_trap and show their dependence on the accretion rate. We discuss the
qualitative picture of accretion and present sample numerical models of the
disk structure. All neutrino-cooled disks regulate themselves to a
characteristic state such that: (1) electrons are mildly degenerate, (2) Y_e ~
0.1, and (3) neutrons dominate the pressure in the disk.


title: The Interstellar N/O Abundance Ratio: Evidence for Local Infall?

abstract:
  Sensitive measurements of the interstellar gas-phase oxygen abundance have
revealed a slight oxygen deficiency ($\sim$ 15%) toward stars within 500 pc of
the Sun as compared to more distant sightlines. Recent $FUSE$ observations of
the interstellar gas-phase nitrogen abundance indicate larger variations, but
no trends with distance were reported due to the significant measurement
uncertainties for many sightlines. By considering only the highest quality
($\geq$ 5 $\sigma$) N/O abundance measurements, we find an intriguing trend in
the interstellar N/O ratio with distance. Toward the seven stars within $\sim$
500 pc of the Sun, the weighted mean N/O ratio is 0.217 $\pm$ 0.011, while for
the six stars further away the weighted mean value (N/O = 0.142 $\pm$ 0.008) is
curiously consistent with the current Solar value (N/O =
0.138$^{+0.20}_{-0.18}$). It is difficult to imagine a scenario invoking
environmental (e.g., dust depletion, ionization, etc.) variations alone that
explains this abundance anomaly. Is the enhanced nitrogen abundance localized
to the Solar neighborhood or evidence of a more widespread phenomenon? If it is
localized, then recent infall of low metallicity gas in the Solar neighborhood
may be the best explanation. Otherwise, the N/O variations may be best
explained by large-scale differences in the interstellar mixing processes for
AGB stars and Type II supernovae.


title:
Identification of the Infrared Counterpart to a Newly Discovered X-ray
  Source in the Galactic Center

abstract:
  We present first results of a campaign to find and identify new compact
objects in the Galactic Center. Selecting candidates from a combination of
Chandra and 2MASS survey data, we search for accretion disk signatures via
infrared spectroscopy. We have found the infrared counterpart to the Chandra
source CXO J174536.1-285638, the spectrum of which has strong Br-gamma and HeI
emission. The presence of CIII, NIII, and HeII indicate a binary system. We
suspect that the system is some form of high-mass binary system, either a
high-mass X-ray binary or a colliding wind binary.


title:
On the consistency of the peculiar GRBs 060218 and 060614 with the Ep,i
  - Eiso correlation

abstract:
  We analyze and discuss the position of GRB 060218 and GRB 060614 in the Ep,i
- Eiso plane. GRB 060218 is important because of its similarity with GRB
980425, the proto-type event of the GRB-SN connection. While GRB 980425 is an
outlier of the Ep,i - Eiso correlation, we find that GRB 060218 is fully
consistent with it. This evidence, combined with the `chromatic' behavior of
the afterglow light curves, is at odds with the hypothesis that GRB 060218 was
a `standard' GRB seen off-axis and supports the existence of a class of truly
sub--energetic GRBs. GRB 060614 is a peculiar event not accompanied by a bright
Supernova. Based on published spectral information, we find that also this
event is consistent with the Ep,i - Eiso correlation. We discuss the
implications of our results for the rate of sub--energetic GRBs, the GRB/SN
connection and the properties of the newly discovered sub-class of long GRBs
not associated with bright Supernovae. We have included in our analysis other
recent GRBs with clear evidence (or clear no evidence) of associated SNe.


title:
Survey for Galaxies Associated with z~3 Damped Lyman alpha Systems II:
  Galaxy-Absorber Correlation Functions

abstract:
  We use 211 galaxy spectra from our survey for Lyman break galaxies (LBGs)
associated with 11 damped Lyman alpha systems (DLAs) to measure the
three-dimensional LBG auto-correlation and DLA-LBG cross-correlation functions
with the primary goal of inferring the mass of DLAs at z~3. Conventional
binning of the data while varying both r_0 and gamma parameters of the fiducial
model of the correlation function xi(r)=(r/r_0)^{-gamma} resulted in the best
fit values and 1 sigma uncertainties of r_0=2.65+/-0.48, gamma=1.55+/-0.40 for
the LBG auto-correlation and r_0=3.32+/-1.25, gamma=1.74+/-0.36 for DLA-LBG
cross-correlation function. To circumvent shortcomings found in binning small
datasets, we perform a maximum likelihood analysis based on Poisson statistics.
  The best fit values and 1 sigma confidence levels from this analysis were
found to be r_0=2.91(+1.0,-1.0), gamma=1.21(+0.6,-0.3) for the LBG
auto-correlation and r_0=2.81(+1.4,-2.0), gamma=2.11(+1.3,-1.4) for the DLA-LBG
cross-correlation function. We report a redshift spike of five LBGs with Delta
z = 0.015 of the z=2.936 DLA in the PSS0808+5215 field and find that the
DLA-LBG clustering signal survives when omitting this field from the analysis.
Using the correlation functions measurements and uncertainties, we compute the
z~3 LBG galaxy bias b_LBG to be 1.5<b_LBG<3 corresponding to an average halo
mass of 10^(9.7)<M_LBG<10^(11.6) M_odot and the z~3 DLA galaxy bias b_DLA to be
1.3<b_DLA<4 corresponding to an average halo mass of 10^(9)<M_LBG<10^(12)
M_odot. Lastly, two of the six QSOs discovered in this survey were found to lie
within Delta z = 0.0125 of two of the survey DLAs. We estimate the probability
of this occurring by chance is 1 in 940 and may indicate a possible
relationship between the distribution of QSOs and DLAs at z~3.


title: The halo mass function from the dark ages through the present day

abstract:
  We use an array of high-resolution N-body simulations to determine the mass
function of dark matter haloes at redshifts 10-30. We develop a new method for
compensating for the effects of finite simulation volume that allows us to find
an approximation to the true ``global'' mass function. By simulating a wide
range of volumes at different mass resolution, we calculate the abundance of
haloes of mass 10^{5-12} Msun/h. This enables us to predict accurately the
abundance of the haloes that host the sources that reionize the universe. In
particular, we focus on the small mass haloes (>~10^{5.5-6} Msun/h) likely to
harbour population III stars where gas cools by molecular hydrogen emission,
early galaxies in which baryons cool by atomic hydrogen emission at a virial
temperature of ~10^4K (10^{7.5-8} Msun/h), and massive galaxies that may be
observable at redshift ~10. When we combine our data with simulations that
include high mass halos at low redshift, we find that the best fit to the halo
mass function depends not only on linear overdensity, as is commonly assumed in
analytic models, but also upon the slope of the linear power spectrum at the
scale of the halo mass. The Press-Schechter model gives a poor fit to the halo
mass function in the simulations at all epochs; the Sheth-Tormen model gives a
better match, but still overpredicts the abundance of rare objects at all times
by up to 50%. Finally, we consider the consequences of the recently released
WMAP 3-year cosmological parameters. These lead to much less structure at high
redshift, reducing the number of z=10 ``mini-haloes'' by more than a factor of
two and the number of z=30 galaxy hosts by more than four orders of magnitude.
Code to generate our best-fit halo mass function may be downloaded from
http://icc.dur.ac.uk/Research/PublicDownloads/genmf_readme.html


title: Detection of a Variable Infrared Excess Around SDSS 121209.31+013627.7

abstract:
  We present near-infrared $JHK_s$ photometry and light curves of the candidate
magnetic white dwarf+brown dwarf binary SDSS J121209.31+013627.7 and report on
the detection of near-infrared excess and variability in the $K_s-$band. The
observed near-infrared excess can be explained by the presence of an L7 brown
dwarf and an extra emission source. The $J$ and $H$ light curves appear flat,
which rules out eclipses deeper than 0.2 mag and the presence of an accretion
hot spot on the white dwarf. From the variable $K_s$ lightcurve, we get a
refined period for the system of 88$\pm$1 minutes. We show that the observed
variability in $K_s-$band can be explained by cyclotron emission, which can be
modeled by a small spot on the surface of the white dwarf. SDSS 1212 exhibits
similarities to the ultra-short period polar EF Eridani, however the lack of
evidence for Roche-lobe overflow accretion suggests it may be a pre-polar.


title: Spectroscopy of Young Planetary Mass Candidates with Disks

abstract:
  It is now well established that many young brown dwarfs exhibit
characteristics similar to classical T Tauri stars, including infrared excess
from disks and emission lines related to accretion. Whether the same holds true
for even lower mass objects, namely those near and below the Deuterium-burning
limit, is an important question. Here we present optical spectra of six
isolated planetary mass candidates in Chamaeleon II, Lupus I and Ophiuchus
star-forming regions, recently identified by Allers and collaborators to harbor
substantial mid-infrared excesses. Our spectra, from ESO's Very Large Telescope
and New Technology Telescope, show that four of the targets have spectral types
in the ~M9-L1 range, and three of those also exhibit H_alpha. Their
luminosities are consistent with masses of ~5-15 M_{Jupiter} according to
models of Chabrier, Baraffe and co-workers, thus placing these four objects
among the lowest mass brown dwarfs known to be surrounded by circum-sub-stellar
disks. Our findings bolster the idea that free-floating planetary mass objects
could have infancies remarkably similar to those of Sun-like stars and suggest
the intriguing possibility of planet formation around primaries whose masses
are comparable to those of extra-solar giant planets. Another target appears to
be a brown dwarf (~M8) with prominent H_alpha emission, possibly arising from
accretion. The sixth candidate is likely a background source, underlining the
need for spectroscopic confirmation.


title:
Testing Global Isotropy of Three-Year Wilkinson Microwave Anisotropy
  Probe (WMAP) Data: Temperature Analysis

abstract:
  We examine statistical isotropy of large scale anisotropies of the Internal
Linear Combination (ILC) map, based on three year WMAP data. Our study reveals
no significant deviation from statistical isotropy on large angular scales of
3-year ILC map. Comparing statistical isotropy of 3-year ILC map and 1-year ILC
map, we find a significant improvement in 3-year ILC map which can be due to
the gain model, improved ILC map processing and foreground minimization.


title: High-resolution X-ray Spectroscopy of BD +30 3639

abstract:
  We present preliminary results from the first X-ray gratings spectrometer
observations of a planetary nebula (PN). We have used the Chandra X-ray
Observatory Low Energy Transmission Gratings Spectrometer (LETGS) to observe
the bright, diffuse X-ray source within the well-studied BD +30 3639. The LETGS
spectrum of BD +30 3639 displays prominent and well-resolved emission lines of
H-like C, O, and Ne and He-like O and Ne. Initial modeling indicates a plasma
temperature T_x ~ 2.5x10^6 K and abundance ratios of C/O ~ 20, N/O <~ 1, Ne/O ~
4, and Fe/O <~ 0.1. These results suggest that the X-ray-emitting plasma is
dominated by the shocked fast wind from the emerging PN core, where this wind
gas likely originated from the intershell region of the progenitor asymptotic
giant branch star.


title: On the migration of protogiant solid cores

abstract:
  The increase of computational resources has recently allowed high resolution,
three dimensional calculations of planets embedded in gaseous protoplanetary
disks. They provide estimates of the planet migration timescale that can be
compared to analytical predictions. While these predictions can result in
extremely short migration timescales for cores of a few Earth masses, recent
numerical calculations have given an unexpected outcome: the torque acting on
planets with masses between 5 M_Earth and 20 M_Earth is considerably smaller
than the analytic, linear estimate. These findings motivated the present work,
which investigates existence and origin of this discrepancy or ``offset'', as
we shall call it, by means of two and three dimensional numerical calculations.
We show that the offset is indeed physical and arises from the coorbital
corotation torque, since (i) it scales with the disk vortensity gradient, (ii)
its asymptotic value depends on the disk viscosity, (iii) it is associated to
an excess of the horseshoe zone width. We show that the offset corresponds to
the onset of non-linearities of the flow around the planet, which alter the
streamline topology as the planet mass increases: at low mass the flow
non-linearities are confined to the planet's Bondi sphere whereas at larger
mass the streamlines display a classical picture reminiscent of the restricted
three body problem, with a prograde circumplanetary disk inside a ``Roche
lobe''. This behavior is of particular importance for the sub-critical solid
cores (M <~ 15 M_Earth) in thin (H/r <~0.06) protoplanetary disks. Their
migration could be significantly slowed down, or reversed, in disks with
shallow surface density profiles.


title:
First Surface-resolved Results with the IOTA Imaging Interferometer:
  Detection of Asymmetries in AGB stars

abstract:
  We have measured non-zero closure phases for about 29% of our sample of 56
nearby Asymptotic Giant Branch (AGB) stars, using the 3-telescope Infrared
Optical Telescope Array (IOTA) interferometer at near-infrared wavelengths (H
band) and with angular resolutions in the range 5-10 milliarcseconds. These
nonzero closure phases can only be generated by asymmetric brightness
distributions of the target stars or their surroundings. We discuss how these
results were obtained, and how they might be interpreted in terms of structures
on or near the target stars. We also report measured angular sizes and
hypothesize that most Mira stars would show detectable asymmetry if observed
with adequate angular resolution.


title:
Variability and multi-periodic oscillations in the X-ray light curve of
  the classical nova V4743 Sgr

abstract:
  The classical nova V4743 Sgr was observed with XMM-Newton for about 10 hours
on April 4 2003, 6.5 months after optical maximum. At this time, this nova had
become the brightest supersoft X-ray source ever observed. We present the
results of a time series analysis performed on the X-ray light curve obtained
in this observation, and in a previous shorter observation done with Chandra 16
days earlier. Intense variability, with amplitude as large as 40% of the total
flux, was observed both times. Similarities can be found between the two
observations in the structure of the variations. Most of the variability is
well represented as a combination of oscillations at a set of discrete
frequencies lower than 1.7 mHz. At least five frequencies are constant over the
16 day time interval between the two observations. We suggest that a periods in
the power spectrum of both light curves at the frequency of 0.75 mHz and its
first harmonic are related to the spin period of the white dwarf in the system,
and that other observed frequencies are signatures of nonradial white dwarf
pulsations. A possible signal with a 24000 sec period is also found in the
XMM-Newton light curve: a cycle and a half are clearly identified. This period
is consistent with the 24278 s periodicity discovered in the optical light
curve of the source and thought to be the orbital period of the nova binary
system.


title:
On the CO Near-IR Band and the Line Splitting Phenomenon in the Yellow
  Hypergiant Rho Cassiopeiae

abstract:
  We report on multi-epoch optical and near-infrared spectroscopy around the
first overtone ro-vibrational band of CO in the pulsating yellow hypergiant Rho
Cas, one of the most massive stars in the Galaxy and a candidate SN II
progenitor. We argue that the double cores of the CO absorption lines, that
have previously been attributed to separate circumstellar shells expelled
during its recurrent outbursts, result in fact from a superposition of a wide
absorption line and a narrow central emission line. The CO line doubling
returns over subsequent pulsation cycles, where the superposed line emission
assumes its largest intensity near phases of maximum light. We find that the
morphology and behavior of the CO band closely resemble the remarkable
"line-splitting phenomenon" also observed in optical low-excitation atomic
lines. Based on radiative transport calculations we present a simplified model
of the near-IR CO emission emerging from cooler atmospheric layers in the
immediate vicinity of the photosphere. We speculate that the kinetic
temperature minimum in our model results from a periodical pulsation-driven
shock wave. We further discuss a number of alternative explanations for the
origin of the ubiquitous emission line spectrum, possibly due to a
quasi-chromosphere or a steady shock wave at the interface of a fast expanding
wind and the ISM. We present a number of interesting spectroscopic similarities
between Rho Cas and other types of cool variable supergiants such as the RV Tau
and R CrB stars. We further propose a possibly common mechanism for the
enigmatic outburst behavior of these luminous pulsating cool stars.


title: Chandra and XMM-Newton Observations of a Group of Galaxies HCG 62

abstract:
  We present results from Chandra and XMM-Newton observations of the bright
group of galaxies HCG 62. There are two cavities at about 30'' northeast and
20'' southwest of the central galaxy in the Chandra image. The energy spectrum
shows no significant change in the cavity compared with that in the surrounding
region. The radial X-ray profile is described by a sum of 3-beta components
with core radii about 2, 10, and 160 kpc, respectively. We studied radial
distributions of temperature and metal abundance with joint spectral fit for
the Chandra and XMM-Newton data, and two temperatures were required in the
inner r< 2' (35 kpc) region. The sharp drop of temperature at r about 5'
implies the gravitational mass density even lower than the gas density,
suggesting the gas may not be in hydrostatic equilibrium. Fe and Si abundances
are 1-2 solar at the center and drop to about 0.1 solar at r about 10'. O
abundance is less than 0.5 solar and shows a flatter profile. Observed metal
distribution supports the view that iron and silicon are produced by type Ia
supernova in the central galaxy, while galactic winds by type II supernova have
caused wide distribution of oxygen. The supporting mechanism of the cavity is
discussed. Pressure for the sum of electrons and magnetic field is too low to
displace the hot group gas, and the required pressure due to high energy
protons are nearly 700 times higher than the electron pressure. This leaves the
origin of the cavities a puzzle, and we discuss other possible origins of the
cavities.


title:
Ellipticity in Cosmic Microwave Background as a Tracer of Large-Scale
  Universe

abstract:
  Wilkinson Microwave Anisotropy Probe (WMAP) 3-year data confirm the
ellipticity of anisotropies of Cosmic Microwave Background (CMB) maps, found
previously for Boomerang and WMAP 1-year high sensitivity maps. The low noise
level of the WMAP latter data enable also to show that, the ellipticity is a
property not described by the conventional cosmological model fitting the power
spectrum of CMB. As a large scale anomaly, the ellipticity characteristics are
consistent with the effect of geodesics mixing occurring in hyperbolic
Universe. Its relation to other large scale effects, i.e. to suppressed low
multipoles, as well as to dark energy if the latter is due to vacuum
fluctuations, is then an arising issue.


title:
Transitions between turbulent and laminar superfluid vorticity states in
  the outer core of a neutron star

abstract:
  We investigate the global transition from a turbulent state of superfluid
vorticity to a laminar state, and vice versa, in the outer core of a neutron
star. By solving numerically the hydrodynamic Hall-Vinen-Bekarevich-Khalatnikov
equations for a rotating superfluid in a differentially rotating spherical
shell, we find that the meridional counterflow driven by Ekman pumping exceeds
the Donnelly-Glaberson threshold throughout most of the outer core, exciting
unstable Kelvin waves which disrupt the rectilinear vortex array, creating a
vortex tangle. In the turbulent state, the torque exerted on the crust
oscillates, and the crust-core coupling is weaker than in the laminar state.
This leads to a new scenario for the rotational glitches observed in radio
pulsars: a vortex tangle is sustained in the differentially rotating outer core
by the meridional counterflow, a sudden spin-up event brings the crust and core
into corotation, the vortex tangle relaxes back to a rectilinear vortex array,
then the crust spins down electromagnetically until enough meridional
counterflow builds up to reform a vortex tangle. The turbulent-laminar
transition can occur uniformly or in patches; the associated time-scales are
estimated from vortex filament theory. We calculate numerically the global
structure of the flow with and without an inviscid superfluid component, for
Hall-Vinen and Gorter-Mellink forms of the mutual friction. We also calculate
the post-glitch evolution of the angular velocity of the crust and its time
derivative, and compare the results with radio pulse timing data, predicting a
correlation between glitch activity and Reynolds number.


title:
Is there a caustic crossing in the lensed quasar Q2237+0305
  observational data record?

abstract:
  We re-investigate the gravitationally lensed system Q2237+0305 data record to
quantify the probability of having a caustic crossing in the A component.
Several works assume that this is the case, but no quantitative analysis is
available in the literature. We combine the datasets from the OGLE and GLITP
collaborations to accurately trace the prominent event in the lightcurve for
the A component of the system. Then the observed event is compared with
synthetic light curves derived from trajectories in magnification maps. These
maps are generated using a ray-tracing technique. We take more than 10^9
trajectories and test a wide range of different physical properties of the
lensing galaxy and the source quasar (lens transverse velocity, microlens mass,
source intensity profile and source size). We found that around 75% of our good
trajectories (i.e. that are consistent with the observations) are caustic
crossings. In addition, a high transverse velocity exceeding 300 km/s, a
microlens mass of about 0.1 M_sun and a small standard accretion disk is the
best parameter combination. The results justify the interpretation of the
OGLE-GLITP event in Q2237+0305A as a caustic crossing. Moreover, the physical
properties of the lens and source are in very good agreement with previous
works. We also remark that a standard accretion disk is prefered to those
simpler approaches, and that the former should be used in subsequent
simulations.


title:
Observational evidence for AGN fueling. I. The merging of NGC6104 with a
  companion

abstract:
  We investigate in details the kinematics and morphology of the Seyfert galaxy
NGC6104 in order to identify the mechanism of gas transportation to the active
galactic nucleus (AGN). Our observational data were obtained at the 6-m Special
Astrophysical Observatory telescope with the MPFS integral-field spectrograph
and the SCORPIO universal device in three modes: direct imaging, a scanning
Fabry-Perot interferometer, and long-slit spectroscopy. Images from the HST
archive were invoked to study the structure of the circumnuclear region. An
analysis of deep images has revealed that NGC6104 is in the phase of active
merging with a companion galaxy. We have been able to study the detailed
picture of ionized gas motions up to galactocentric distances of 14 kpc and to
construct the stellar velocity field for the inner region. The radial gas
motions toward the AGN along the central bar play a significant role at
galactocentric distances of 1-5 kpc. In addition, we have detected an outflow
of ionized gas from the nucleus that presumably resulted from the intrusion of
a radio jet into the ambient interstellar medium. Using diagnostic diagrams, we
estimate the contributions from the AGN and star formation to the galactic gas
ionization. We estimate the bar pattern speed by the Tremaine-Weinberg method
and show that the inner ring observed in the galactic images has a resonant
nature. Two possible ring formation scenarios (before and during the
interaction with a companion) are discussed.


title: Magnetic instability in a differentially rotating star

abstract:
  Instabilities in magnetic fields wound up by differential rotation as
reviewed in Spruit (1999) are discussed with some detail and new developments
added. In stellar models which include magnetic torques, the differential
rotation tends to accumulate in the gradients in composition. In view of this,
instability in a $\mu$-gradient is studied in more detail here, resulting in
the detection of a second instability. Its relevance for angular momentum
transport is uncertain, however, since it requires high horizontal field
gradients and would not operate near the pole. Finally, the possibility is
discussed that magnetic instability in a $\mu$-gradient will lead to {\em layer
formation}: the gradients breaking up into small steps of uniform composition
and rotation rate. This would enhance the angular momentum transport across
inhomogeneous zones, and decrease the rotation rates of the end products of
stellar evolution. A recent {\tt astro-ph} submission by Dennisenkov and
Pinsonneault proposing a modification of the instability conditions is shown to
contain a mathematical error.


title:
Force-free magnetosphere of an aligned rotator with differential
  rotation of open magnetic field lines

abstract:
  Here we briefly report on results of self-consistent numerical modeling of a
differentially rotating force-free magnetosphere of an aligned rotator. We show
that differential rotation of the open field line zone is significant for
adjusting of the global structure of the magnetosphere to the current density
flowing through the polar cap cascades. We argue that for most pulsars
stationary cascades in the polar cap can not support stationary force-free
configurations of the magnetosphere.


title:
Density-Functional-Theory Calculations of Matter in Strong Magnetic
  Fields: I. Atoms and Molecules

abstract:
  We present new ab initio calculations of the electronic structure of various
atoms and molecules in strong magnetic fields ranging from B=10^12 G to 2x10^15
G, appropriate for radio pulsars and magnetars. For these field strengths, the
magnetic forces on the electrons dominate over the Coulomb forces, and to a
good approximation the electrons are confined to the ground Landau level. Our
calculations are based on the density functional theory, and use a local
magnetic exchange-correlation function which is tested to be reliable in the
strong field regime. Numerical results of the ground-state energies are given
for H_N (up to N=10), He_N (up to N=8), C_N (up to N=5) and Fe_N (up to N=3),
as well as for various ionized atoms. Fitting formulae for the B-dependence of
the energies are also given. In general, as N increases, the binding energy per
atom in a molecule, |E_N|/N, increases and approaches a constant value. For all
the field strengths considered in this paper, hydrogen, helium, and carbon
molecules are found to be bound relative to individual atoms (although for B
less than a few x 10^12 G, the relative binding between C and C_2 is small).
Iron molecules are not bound at B<10^13 G, but become energetically more
favorable than individual atoms at larger field strengths.


title: Spectral variability of planetary nebulae and related objects

abstract:
  The results of long-term spectral observations were used to search for
changes in planetary nebulae and emission-line stars. Significant increase of
excitation degree is found in two objects: M1-6 and M1-11.


title:
Atmosphere Models of Magnetized Neutron Stars: QED Effects, Radiation
  Spectra, and Polarization Signals

abstract:
  Theoretical modeling of surface emission from magnetized neutron stars (NSs)
requires proper treatment of QED effects, in particular the effect of photon
mode conversion due to the ``vacuum resonance'' between plasma and vacuum
polarization. Previous NS atmosphere models incorporated this effect
approximately, using transfer equations for the photon modes which are
inadequate near the vacuum resonance, particularly for field strengths around
$B_l\simeq 7\times 10^{13}$ G, where the vacuum resonance occurs near the
photosphere. In this paper, we provide an accurate treatment of the QED-induced
mode conversion effect in NS atmosphere models, employing both the modal
radiative transfer equations, coupled with an accurate mode conversion
probability at the resonance, and the full evolution equations for the photon
Stokes parameters. In doing so, we are able to quantitatively calculate the
effects of vacuum polarization on the atmosphere emission spectra, beam
patterns, and polarizations for the entire range of field strengths,
$B=10^{12}-10^{15}$ G. We find that for NSs with $B\ga 2 B_l$, vacuum
polarization reduces the widths of spectral features, and softens the hard
spectral tail typical of magnetized atmosphere models. For $B\la B_l/2$, vacuum
polarization does not change the emission spectra, but can significantly affect
the polarization signals. We show that vacuum polarization induces a unique
energy-dependent linear polarization signature, and that circular polarization
can be generated in the magnetospheres of rapidly rotating NSs. We discuss the
implications of our results for recent observations of thermally emitting
isolated NSs and magnetars, as well as the prospects for future spectral and
polarization observations.


title: Probing Primordial Magnetic Fields with the 21cm Fluctuations

abstract:
  Primordial magnetic fields possibly generated in the very early universe are
one of the candidates for the origin of magnetic fields observed in many
galaxies and galaxy clusters. After recombination, the dissipation process of
the primordial magnetic fields increases the baryon temperature. The Lorentz
force acts on the residual ions and electrons to generate density fluctuations.
These effects are imprinted on the cosmic microwave background (CMB) brightness
temperature fluctuations produced by the neutral hydrogen 21cm line. We
calculate the angular power spectrum of brightness temperature fluctuations for
the model with the primordial magnetic fields of a several nano Gauss strength
and a power-law spectrum. It is found that the overall amplitude and the shape
of the brightness temperature fluctuations depend on the strength and the
spectral index of the primordial magnetic fields. Therefore, it is expected
that the observations of the CMB brightness temperature fluctuations give us a
strong constraint on the primordial magnetic fields.


title:
The XMM-LSS Survey: A well controlled X-ray cluster sample over the D1
  CFHTLS area

abstract:
  We present the XMM-LSS cluster catalogue corresponding to the CFHTLS D1 area.
The list contains 13 spectroscopically confirmed, X-ray selected galaxy
clusters over 0.8 deg2 to a redshift of unity and so constitutes the highest
density sample of clusters to date. Cluster X-ray bolometric luminosities range
from 0.03 to 5x10^{44} erg/s. In this study, we describe our catalogue
construction procedure: from the detection of X-ray cluster candidates to the
compilation of a spectroscopically confirmed cluster sample with an explicit
selection function. The procedure further provides basic X-ray products such as
cluster temperature, flux and luminosity. We detected slightly more clusters
with a (0.5-2.0 keV) X-ray fluxes of >2x10^{-14} erg/s/cm^{-2} than we expected
based on expectations from deep ROSAT surveys. We also present the
Luminosity-Temperature relation for our 9 brightest objects possessing a
reliable temperature determination. The slope is in good agreement with the
local relation, yet compatible with a luminosity enhancement for the 0.15 < z<
0.35 objects having 1 < T < 2 keV, a population that the XMM-LSS is identifying
systematically for the first time. The present study permits the compilation of
cluster samples from XMM images whose selection biases are understood. This
allows, in addition to studies of large-scale structure, the systematic
investigation of cluster scaling law evolution, especially for low mass X-ray
groups which constitute the bulk of our observed cluster population. All
cluster ancillary data (images, profiles, spectra) are made available in
electronic form via the XMM-LSS cluster database.


title: SDSS J160043.6+074802.9: a very rapid sdO pulsator

abstract:
  We report the serendipitous discovery of the Sloan Digital Sky Survey star,
SDSS J160043.6+074802.9 to be a very rapid pulsator. The variation is dominated
by a frequency near 8380 microHz (period = 119.33 s) with a large amplitude
(0.04 mag) and its first harmonic at 16760 microHz (59.66 s; 0.005 mag). In
between these frequencies, we find at least another 8 variations with periods
between 62 and 118 seconds and amplitudes between about 0.007 and 0.003 mag;
weaker oscillations might also be present. Preliminary spectrograms from the
performance verification phase of the Southern African Large Telescope indicate
that SDSS J160043.6+074802.9 is a spectroscopic binary consisting of an sdO
star and a late-type main-sequence companion. This makes it the first
unambiguous detection of such an sdO star to pulsate, and certainly the first
found to exhibit multi-frequency variations.


title:
Frequency, splitting, linewidth and amplitude estimates of low-l p modes
  of alpha Cen A: analysis of WIRE photometry

abstract:
  We present results of fitting the 50-day time series of photometry of alpha
Cen A taken by the WIRE satellite in 1999. Both power spectrum and
autocovariance function (ACF) fitting techniques were used in an attempt to
determine mode frequencies, rotational splittings, lifetimes and amplitudes of
low-l p-modes. In all, using both techniques, we managed to fit 18 modes (seven
l = 0, eight l = 1 and three l = 2) with frequencies determined to within 1 - 2
micro-Hz. These estimates are shown to be 0.6 +/- 0.3 micro-Hz lower, on
average, than the frequencies determined from two other more recent studies
(Bouchy & Carrier, 2002; Bedding et al. 2004) which used data gathered about 19
months after the WIRE observations. This could be indicative of an activity
cycle, although due to the large uncertainty, more data would be needed to
confirm this.
  Over a range of 1700 to 2650 micro-Hz we were also able to use the ACF
fitting to determine an average lifetime of 3.9 +/- 1.4 days, and an average
rotational splitting of 0.54 +/- 0.22 micro-Hz, which is the first ever
reliable estimate of this parameter. In contrast to the ACF, the power spectrum
fitting was shown to return significantly biased results for these parameters.


title: A long-period, violently-variable X-ray source in a young SNR

abstract:
  Observations with the Newton X-ray Multimirror Mission (XMM) show a strong
periodic modulation at 6.67+/-0.03 hours of the X-ray source at the centre of
the 2,000-year-old supernova remnant RCW 103. No fast pulsations are visible.
If genetically tied to the supernova remnant, the source could either be an
X-ray binary, comprising a compact object and a low-mass star in an eccentric
orbit, or an isolated neutron star. In the latter case, its age-period
combination would point to a peculiar magnetar, dramatically slowed-down,
possibly by a supernova debris disc. Both scenarios require non-standard
assumptions on the formation and evolution of compact objects in supernova
explosions.


title:
Invariant manifolds, phase correlations of chaotic orbits and the spiral
  structure of galaxies

abstract:
  In the presence of a strong $m=2$ component in a rotating galaxy, the phase
space structure near corotation is shaped to a large extent by the {\it
invariant manifolds} of the short period family of unstable periodic orbits
terminating at L$_1$ or L$_2$. The main effect of these manifolds is to create
robust {\it phase correlations} among a number of chaotic orbits large enough
to support a {\it spiral} density wave outside corotation. The phenomenon is
described theoretically by soliton-like solutions of a Sine-Gordon equation.
Numerical examples are given in an N-Body simulation of a barred spiral galaxy.
In these examples, we demonstrate how the projection of unstable manifolds in
configuration space reproduces essentially the entire observed bar-spiral
pattern.


title:
Formation and structure of the three Neptune-mass planets system around
  HD69830

abstract:
  Since the discovery of the first giant planet outside the solar system in
1995 (Mayor & Queloz 1995), more than 180 extrasolar planets have been
discovered. With improving detection capabilities, a new class of planets with
masses 5-20 times larger than the Earth, at close distance from their parent
star is rapidly emerging. Recently, the first system of three Neptune-mass
planets has been discovered around the solar type star HD69830 (Lovis et al.
2006). Here, we present and discuss a possible formation scenario for this
planetary system based on a consistent coupling between the extended core
accretion model and evolutionary models (Alibert et al. 2005a, Baraffe et al.
2004,2006). We show that the innermost planet formed from an embryo having
started inside the iceline is composed essentially of a rocky core surrounded
by a tiny gaseous envelope. The two outermost planets started their formation
beyond the iceline and, as a consequence, accrete a substantial amount of water
ice during their formation. We calculate the present day thermodynamical
conditions inside these two latter planets and show that they are made of a
rocky core surrounded by a shell of fluid water and a gaseous envelope.


title:
Modelling spectral line profiles of wind-wind shock emissions from
  massive binary systems

abstract:
  One of the most intriguing spectral features of WR binary stars is the
presence of time-dependent line profiles. Long term observations of several
systems revealed the periodicity of this variability, synchronized with the
orbital movement. Several partially successful models have been proposed to
reproduce the observed data. The most promising assume that the origin of the
emission is the wind-wind interaction zone. In this scenario, two high velocity
and dense winds produce a strong shock layer, responsible for most of the
X-rays observed from these systems. As the secondary star moves along its
orbital path, the shock region of conical shape, changes its position with
relation to the line of sight. As a consequence, the stream measured Doppler
shift presents time variations resulting in position changes of the spectral
line. In our work, we present an alternative model, introducing turbulence in
the shock layer to account for the line broadening and opacity effects for the
asymmetry in the line profiles. We showed that the gas turbulence avoids the
need of an unnaturally large contact layer thickness to reproduce line
broadening. Also, we demonstrated that if the emission from the opposing cone
surface is absorbed, the result is a single peaked profile. This result fully
satisfies the recent data obtained from massive binary systems, and can help on
the determination of both winds and orbital parameters. We successfully applied
this model to the Br22 system and determined its orbital parameters.


title:
The XMM Large Scale Structure survey: The X-ray pipeline and survey
  selection function

abstract:
  We present the X-ray pipeline developed for the purpose of the cluster search
in the XMM-LSS survey. It is based on a two-stage procedure via a dedicated
handling of the Poisson nature of the signal: (1) source detection on
multi-resolution wavelet filtered images; (2) source analysis by means of a
maximum likelihood fit to the photon images. The source detection efficiency
and characterisation are studied through extensive Monte-Carlo simulations.
This led us to define two samples of extended sources: the C1 class that is
uncontaminated, and the less restrictive C2 class that allows for 50%
contamination. The resulting predicted selection function is presented and the
comparison to the current XMM-LSS confirmed cluster sample shows very good
agreement. We arrive at average predicted source densities of about 7 C1 and 12
C2 per deg2, which is higher than any available wide field X-ray survey. We
finally notice a substantial deviation of the predicted redshift distribution
for our samples from the one obtained using the usual assumption of a flux
limited sample.


title: XMM-Newton observations of AM CVn binaries: V396 Hya & SDSS J1240-01

abstract:
  We present the results of XMM-Newton observations of two AM CVn systems -
V396 Hya and SDSS J1240-01. Both systems are detected in X-rays and in the UV:
neither shows coherent variability in their light curves. We compare the rms
variability of the X-ray and UV power spectra of these sources with other AM
CVn systems. Apart from ES Cet, AM CVn sources are not strongly variable in
X-rays, while in the UV the degree of variability is related to the systems
apparent brightness. The X-ray spectra of V396 Hya and SDSS J1240-01 show
highly non-solar abundances, requiring enhanced nitrogen to obtain good fits.
We compare the UV and X-ray luminosities for 7 AM CVn systems using recent
distances. We find that the X-ray luminosity is not strongly dependent upon
orbital period. However, the UV luminosity is highly correlated with orbital
period with the UV luminosity decreasing with increasing orbital period. We
expect that this is due to the accretion disk making an increasingly strong
contribution to the UV emission at shorter periods. The implied luminosities
are in remarkably good agreement with predictions.


title:
Oscillating axion bubbles as alternative to supermassive black holes at
  galactic centers

abstract:
  Recent observations of near-infrared and X-ray flares from Sagittarius A*,
which is believed to be a supermassive black hole at the Galactic center, show
that the source exhibits about 20-minute periodic variability. Here we provide
arguments based on a quantitative analysis that supermassive objects at
galactic centers may be bubbles of dark matter axions rather than black holes.
An oscillating axion bubble can explain periodic variability of Sagittarius A*
and yields the axion mass about 0.6 meV which fits in the open axion mass
window. The bubble scenario with no other free parameters explains lack of
supermassive "black holes" with mass M<10^6 M_{Sun}. Low-mass bubbles decay
fast and as a result are very rare. We also found that the mass of an axion
bubble can not exceed 1.5\times 10^9 M_{Sun}, in agreement with the upper limit
on the supermassive "black hole" mass obtained from observations. Our finding,
if confirmed, suggests that Einstein general relativity is invalid for strong
gravity and the gravitational field for the bubble effectively becomes
repulsive at large potential. Imaging a shadow of the "black hole" at the
Galactic center with VLBI in the next decade can distinguish between the black
hole and the oscillating axion bubble scenarios. In the case of axion bubble, a
steady shadow will not be observed. Instead, the shadow will appear and
disappear periodically with a period of about 20 min.


title: Neutrinos, Fission Cycling, and the r-process

abstract:
  It has long been suggested that fission cycling may play an important role in
the r-process. Fission cycling can only occur in a very neutron rich
environment. In traditional calculations of the neutrino driven wind of the
core-collapse supernova, the environment is not sufficiently neutron rich to
produce the r-process elements. However, we show that with a reduction of the
electron neutrino flux coming from the supernova, fission cycling does occur
and furthermore it produces an abundance pattern which is consistent with
observed r-process abundance pattern in halo stars. Such a reduction can be
caused by active-sterile neutrino oscillations or other new physics.


title: The Origin of Primordial Magnetic Fields

abstract:
  (abridged) We suggest here that the large scale fields $\sim \mu$G, observed
in galaxies at both high and low redshifts by Faraday Rotation Measurements
(FRMs), have their origin in the electromagnetic fluctuations that naturally
occurred in the dense hot plasma that existed just after the QHPT. We evolve
the predicted fields to the present time. The size of the region containing a
coherent magnetic field increased due to the fusion (polymerization) of smaller
regions. Magnetic fields (MFs) $\sim 10 \mu G$ over a comoving $\sim 1$ pc
region are predicted at redshift z $\sim 10$. These fields are orders of
magnitude greater than those predicted in previous scenarios for creating
primordial magnetic fields. Line-of-sight average magnetic fields (MFs) $\sim$
$10^{-2}$ $\mu$G, valid for FRMs, are obtained over a 1 Mpc comoving region at
the redshift z $\sim$ 10.
  In the collapse to a galaxy (comoving size $\sim$ 30 kpc) at z $\sim$ 10, the
fields are amplified to $\sim 10 \mu$G. This indicates that the MFs created
immediately after the QHPT, predicted by the Fluctuation-Dissipation Theorem,
could be the origin of the $\sim \mu G$ fields observed by FRMs in galaxies at
both high and low redshifts.


title:
Optical parameters of the nonisothermal Uranus's and Neptune's
  atmospheres

abstract:
  A method of the calculation of optical parameters of the nonisothermal giant
planet atmospheres was developed using detailed intensity data of Raman
scattering. We have used the model of Morozhenko (A.V. Morozhenko, 1997) as a
baseline. In such a way, using observational data of Uranus and Neptune
(E.Karkoschka, 1994), the spectral values of ratio of optical depth components:
aerosol and gas components \tau a/ \tau R, absorbing and scattering components
\tau a/ \tau R, and also single scattering albedo of aerosol component
corrected for Raman scattering \omega were obtained (where \tau a, \tau R are
aerosol and gas components, and \tau ? is absorbing components of effective
optical depths of the formation of diffusely reflected irradiation). The
averaged value of ratio \tau a/ \tau R is 0.96 but it slowly decreases in the
spectral range of 350-450nm for Uranus and \tau a/ \tau R is 1.35 for Neptune.


title:
The Light Curve Variations of The Active Binaries With Hot Subdwarf
  Component

abstract:
  We present the light curve variations of the two active binaries with hot
subdwarf component. According to the brightness variations outside of the
eclipses, the giant components of the systems are chromospherically active
stars. The dark and cool active structures on this components cause the
variations of the total light of the systems.


title: Catalogue of Planetary Objects. Version 2006.0

abstract:
  The analysis of the density and brightness of big planets satellites, main
asteroid belt objects, Kuiper belt objects and centaurs has been carried out as
well as the analysis of suspected unseen satellites of the stars. According to
the date on the first of January 2006 the catalogue of planetary objects has
been compiled.


title:
Carbon Monoxide in Comet 9P/Tempel 1 before and after the Deep Impact
  Encounter

abstract:
  One of the goals of the Hubble Space Telescope program to observe periodic
comet 9P/Tempel 1 in conjunction with NASA's Deep Impact mission was to study
the generation and evolution of the gaseous coma resulting from the impact. For
this purpose, the Solar Blind Channel of the Advanced Camera for Surveys was
used with the F140LP filter which is sensitive primarily to the ultraviolet
emission (>1400 A) from the CO Fourth Positive system. Following the impact we
detected an increase in brightness, which if all due to CO corresponds to 1.5 x
10^31 molecules or a mass of 6.6 x 10^5 kg, an amount that would normally be
produced by 7-10 hours of quiescent outgassing from the comet. This number is
less than or equal to 10% of the number of water molecules excavated, and
suggests that the volatile content of the material excavated by the impact did
not differ significantly from the surface or near sub-surface material
responsible for the quiescent outgassing of the comet.


title: Period Change of Eclipsing Binaries from the ASAS Catalog

abstract:
  We present a preliminary statistical analysis of a period change of eclipsing
binaries from the ASAS Catalog of Variable Stars. For each contact and
semidetached system brighter than 13.3$mag$ (in V) with a period shorter than
0.4 days and at least 300 observation points we have found an angular velocity
$\omega$ and its time derivative $\frac{d\omega}{dt}$. According to our
accuracy there is no evidence that average $\frac{d\omega}{dt}$ differs from 0.
Light curves for selected stars are presented.


title:
Causes of Observed Long-Periodic Variations of the Polarization at Polar
  Regions of Jupiter

abstract:
  Data of 23-years of Jupiter polarimetric observations (1981- 2004) have been
reprocessed using new improved technique. The data from other observers have
been added to the analysis (1971-74). Anticorrelation between asymmetry of
polarization and insolation has been found. The mechanism of influence of
seasons changing (through temperature variations) on north-south asymmetry of
polarization formation has been proposed. Also a possibility of existence of
influence of solar cosmic rays flux on polarization value is noted.