title: High Mass Star Formation by Gravitational Collapse of Massive Cores

abstract:
  The current generation of millimeter interferometers have revealed a
population of compact (r <~ 0.1 pc), massive (M ~ 100 Msun) gas cores that are
the likely progenitors of massive stars. I review models for the evolution of
these objects from the observed massive core phase through collapse and into
massive star formation, with particular attention to the least well-understood
aspects of the problem: fragmentation during collapse, interactions of newborn
stars with the gas outside their parent core, and the effects of radiation
pressure feedback. Through a combination of observation, analytic argument, and
numerical simulation, I develop a model for massive star formation by
gravitational collapse in which massive cores collapse to produce single stars
or (more commonly) small-multiple systems, and these stars do not gain
significant mass from outside their parent core by accretion of either gas or
other stars. Collapse is only very slightly inhibited by feedback from the
massive star, thanks to beaming of the radiation by a combination of
protostellar outflows and radiation-hydrodynamic instabilities. Based on these
findings, I argue that many of the observed properties of young star clusters
can be understood as direct translations of the properties of their gas phase
progenitors. Finally, I discuss unsolved problems in the theory of massive star
formation, and directions for future work on them.


title: The Metal-Strong Damped Lyman-alpha Systems

abstract:
  We have identified a metal-strong (logN(Zn+) > 13.15 or logN(Si+) > 15.95)
DLA (MSDLA) population from an automated quasar (QSO) absorber search in the
Sloan Digital Sky Survey Data Release 3 (SDSS-DR3) quasar sample, and find that
MSDLAs comprise ~5% of the entire DLA population with z_abs > 2.2 found in QSO
sightlines with r < 19.5. We have also acquired 27 Keck ESI follow-up spectra
of metal-strong candidates to evaluate our automated technique and examine the
MSDLA candidates at higher resolution. We demonstrate that the rest equivalent
widths of strong ZnII 2026 and SiII 1808 lines in low-resolution SDSS spectra
are accurate metal-strong indicators for higher-resolution spectra, and predict
the observed equivalent widths and signal-to-noise ratios needed to detect
certain extremely weak lines with high-resolution instruments. We investigate
how the MSDLAs may affect previous studies concerning a dust-obscuration bias
and the N(HI)-weighted cosmic mean metallicity <Z(z)>. Finally, we include a
brief discussion of abundance ratios in our ESI sample and find that underlying
mostly Type II supernovae enrichment are differential depletion effects due to
dust (and in a few cases quite strong); we present here a handful of new Ti and
Mn measurements, both of which are useful probes of depletion in DLAs. Future
papers will present detailed examinations of particularly metal-strong DLAs
from high-resolution KeckI/HIRES and VLT/UVES spectra.


title:
Point Process Algorithm: A New Bayesian Approach for Planet Signal
  Extraction with the Terrestrial Planet Finder

abstract:
  The capability of the Terrestrial Planet Finder Interferometer (TPF-I) for
planetary signal extraction, including both detection and spectral
characterization, can be optimized by taking proper account of instrumental
characteristics and astrophysical prior information. We have developed the
Point Process Algorithm (PPA), a Bayesian technique for extracting planetary
signals using the sine-chopped outputs of a dual nulling interferometer. It is
so-called because it represents the system being observed as a set of points in
a suitably-defined state space, thus providing a natural way of incorporating
our prior knowledge of the compact nature of the targets of interest. It can
also incorporate the spatial covariance of the exozodi as prior information
which could help mitigate against false detections. Data at multiple
wavelengths are used simultaneously, taking into account possible spectral
variations of the planetary signals. Input parameters include the RMS
measurement noise and the a priori probability of the presence of a planet. The
output can be represented as an image of the intensity distribution on the sky,
optimized for the detection of point sources. Previous approaches by others to
the problem of planet detection for TPF-I have relied on the potentially
non-robust identification of peaks in a "dirty" image, usually a correlation
map. Tests with synthetic data suggest that the PPA provides greater
sensitivity to faint sources than does the standard approach (correlation map +
CLEAN), and will be a useful tool for optimizing the design of TPF-I.


title: The Submillimeter Polarization of Sgr A*

abstract:
  We report on the submillimeter properties of Sagittarius A* derived from
observations with the Submillimeter Array and its polarimeter. We find that the
spectrum of Sgr A* between 230 and 690 GHz is slightly decreasing when measured
simultaneously, indicating a transition to optically thin emission around
300-400 GHz. We also present very sensitive and well calibrated measurements of
the polarization of Sgr A* at 230 and 345 GHz. With these data we are able to
show for the first time that the polarization of Sgr A* varies on hour
timescales, as has been observed for the total intensity. On one night we find
variability that may arise from a polarized "blob" orbiting the black hole.
Finally, we use the ensemble of observations to determine the rotation measure.
This represents the first statistically significant rotation measure
determination and the only one made without resorting to comparing position
angles measured at separate epochs. We find a rotation measure of
(-5.6+/-0.7)x10^5 rad/m^2, with no evidence for variability on inter-day
timescales at the level of the measurement error. The stability constrains
interday fluctuations in the accretion rate to 8%. The mean intrinsic
polarization position angle is 167+/-7 degrees and we detect variations of
31+18/-9 degrees. This separation of intrinsic polarization changes and
possible rotation measure fluctuations is now possible because of the frequency
coverage and sensitivity of our data. The observable rotation measure restricts
the accretion rate to the range 2x10^{-7} Msun/yr to 2x10^{-9} Msun/yr, if the
magnetic field is near equipartition and ordered.


title:
On the maximum amplitude and coherence of the kilohertz quasi-periodic
  oscillations in low-mass X-ray binaries

abstract:
  I study the behaviour of the maximum rms fractional amplitude, $r_{\rm max}$
and the maximum coherence, $Q_{\rm max}$, of the kilohertz quasi-periodic
oscillations (kHz QPOs) in a dozen low-mass X-ray binaries. I find that: (i)
The maximum rms amplitudes of the lower and the upper kHz QPO, $r^{\ell}_{\rm
max}$ and $r^{\rm u}_{\rm max}$, respectively, decrease more or less
exponentially with increasing luminosity of the source; (ii) the maximum
coherence of the lower kHz QPO, $Q^{\ell}_{\rm max}$, first increases and then
decreases exponentially with luminosity, at a faster rate than both
$r^{\ell}_{\rm max}$ and $r^{\rm u}_{\rm max}$; (iii) the maximum coherence of
the upper kHz QPO, $Q^{\rm u}_{\rm max}$, is more or less independent of
luminosity; and (iv) $r_{\rm max}$ and $Q_{\rm max}$ show the opposite
behaviour with hardness of the source, consistent with the fact that there is a
general anticorrelation between luminosity and spectral hardness in these
sources. Both $r_{\rm max}$ and $Q_{\rm max}$ in the sample of sources, and the
rms amplitude and coherence of the kHz QPOs in individual sources show a
similar behaviour with hardness. This similarity argues against the
interpretation that the drop of coherence and rms amplitude of the lower kHz
QPO at high QPO frequencies in individual sources is a signature of the
innermost stable circular orbit around a neutron star. I discuss possible
interpretations of these results in terms of the modulation mechanisms that may
be responsible for the observed variability.


title: S0 galaxies in Fornax: data and kinematics

abstract:
  We have obtained long-slit spectroscopy for a sample of 9 S0 galaxies in the
Fornax Cluster using the FORS2 spectrograph at the 8.2m ESO VLT. From these
data, we have extracted the kinematic parameters, comprising the mean velocity,
velocity dispersion and higher-moment H3 and H4 coefficients, as a function of
position along the major axes of these galaxies. Comparison with published
kinematics indicates that earlier data are often limited by their lower
signal-to-noise ratio and relatively poor spectral resolution. The greater
depth and higher dispersion of the new data mean that we reach well beyond the
bulges of these systems, probing their disk kinematics in some detail for the
first time. Qualitative inspection of the results for individual galaxies shows
that they are not entirely simple systems, perhaps indicating a turbulent past.
Nonetheless, we are able to derive reliable circular velocities for most of
these systems, which points the way toward a study of their Tully-Fisher
relation. This study, along with an analysis of the stellar populations of
these systems out to large galactocentric distances, will form the bases of
future papers exploiting these new high-quality data, hopefully shedding new
light on the evolutionary history of these systems.


title:
Expressing the equation of state parameter in terms of the three
  dimensional cosmic shear

abstract:
  We study the functional dependence of the spin-weighted angular moments of
the two-point correlation function of the three dimensional cosmic shear on the
expansion history of the universe. We first express the redshift dependent
total equation of state parameter in terms of the growing mode of the gauge
invariant metric perturbation in the conformal-Newtonian gauge for the case of
adiabatic perturbations. We then express the redshift dependent angular moments
of the shear two-point correlation function as an integral in terms of the
metric perturbation. We present the final explicit expression for the case of a
Harrison-Zeldovich spectrum of primordial perturbations. Our analysis is
restricted to the linear regime. We use our results to make a preliminary study
of the required sensitivity that will allow cosmic shear observations to add
significant information about the expansion history of the universe.


title:
Hydrodynamic Approach to the Evolution of Cosmic Structures II: Study of
  N-body Simulations at z=0

abstract:
  We present a series of cosmological N-body simulations which make use of the
hydrodynamic approach to the evolution of structures (Dominguez 2000). This
approach addresses explicitly the existence of a finite spatial resolution and
the dynamical effect of subresolution degrees of freedom. We adapt this method
to cosmological simulations of the standard LCDM structure formation scenario
and study the effects induced at redshift z=0 by this novel approach on the
large-scale clustering patterns as well as (individual) dark matter halos.
Comparing these simulations to usual N-body simulations, we find that (i) the
new (hydrodynamic) model entails a proliferation of low--mass halos, and (ii)
dark matter halos have a higher degree of rotational support. These results
agree with the theoretical expectation about the qualitative behaviour of the
"correction terms" introduced by the hydrodynamic approach: these terms act as
a drain of inflow kinetic energy and a source of vorticity by the small-scale
tidal torques and shear stresses.


title: Light Dark Matter Annihilations into Two Photons

abstract:
  We compute the pair annihilation cross section of light (spin-0) dark matter
particles into two photons and discuss the detectability of the monochromatic
line associated with these annihilations.


title:
Old open clusters as key tracers of Galactic chemical evolution. I. Fe
  abundances in NGC 2660, NGC 3960, and Berkeley 32

abstract:
  We obtained high-resolution UVES/FLAMES observations of a sample of nine old
open clusters spanning a wide range of ages and Galactocentric radii. The goal
of the project is to investigate the radial metallicity gradient in the disk,
as well as the abundance of key elements (alpha and Fe-peak elements). In this
paper we present the results for the metallicity of three clusters: NGC 2660
(age ~1 Gyr, Galactocentric distance of 8.68 kpc), NGC 3960 (~ 1 Gyr, 7.80
kpc), and Be 32 (~6-7 Gyr, 11.30 kpc). For Be 32 and NGC 2660, our study
provides the first metallicity determination based on high-resolution spectra.
We performed equivalent width analysis with the spectral code MOOG, which
allows us to define a metallicity scale and build a homogeneous sample. We find
that NGC 3960 and NGC 2660 have a metallicity that is very close to solar
([Fe/H]=+0.02 and +0.04, respectively), while the older Be 32 turns out to have
[Fe/H]=$-$0.29.


title: Simulating the Zody Emission in the Planck Mission

abstract:
  The increasing sensitivity of cosmic microwave background (CMB) missions will
require to significantly improve the accuracy in the subtraction of the various
sources of Galactic foreground, from the most relevant components (synchrotron,
dust and free-free emission) to those usually considered of minor relevance in
CMB experiments. With respect to other Galactic diffuse components, the
Zodiacal Light Emission (ZLE) is peculiar, depending not only on the observing
direction but also on the location of the observer within the Solar System: ZLE
behaves then as a large scale, time-dependent foreground. Starting from the
existing far-infrared ZLE models, we discuss the impact of ZLE contribution in
CMB maps and the level of contamination in time ordered data and maps expected
from the forthcoming Planck space mission as well as the Planck capability to
increase our knowledge of the ZLE properties.


title: RHESSI Results -- Time For a Rethink?

abstract:
  Hard X-rays and gamma-rays are the most direct signatures of energetic
electrons and ions in the sun's atmosphere which is optically thin at these
energies and their radiation involves no coherent processes. Being collisional
they are complementary to gyro-radiation in probing atmospheric density as
opposed to magnetic field and the electrons are primarily 10--100 keV in
energy, complementing the (>100 keV) electrons likely responsible for microwave
bursts.
  The pioneering results of the Ramaty High Energy Solar Spectroscopic Imager
(RHESSI) are raising the first new major questions concerning solar energetic
particles in many years. Some highlights of these results are discussed --
primarily around RHESSI topics on which the authors have had direct research
involvement -- particularly when they are raising the need for re-thinking of
entrenched ideas. Results and issues are broadly divided into discoveries in
the spatial, temporal and spectral domains, with the main emphasis on flare
hard X-rays/fast electrons but touching also on gamma-rays/ions, non-flare
emissions, and the relationship to radio bursts.


title:
A physical model for active galactic nuclei with double-peaked broad
  emission lines

abstract:
  The double-peaked broad emission lines are usually thought to be linked to
accretion disks, however, the local viscous heating in the line-emitting disk
portion is usually insufficient for the observed double-peaked broad-line
luminosity in most sources. Our calculations show that only a small fraction (<
2.3 per cent) of the radiation from the RIAF in the inner region of the disk
can photo-ionize the line-emitting disk portion, because the solid angle of the
outer disk portion subtended to the inner region of the RIAF is too small. We
propose that only those AGNs with sufficient matter above the disk (slowly
moving jets or outflows) can scatter enough photons radiated from the inner
disk region to the outer line-emitting disk portion. Our model predicts a
power-law r-dependent line emissivity with an index ~2.5, which is consistent
with \beta~2-3 required by the model fittings for double-peaked line profiles.
Using a sample of radio-loud double-peaked line emitters, we show that the
outer disk regions can be efficiently illuminated by the photons scattered from
the electron-positron jets with \gamma_j<2. It is consistent with the fact that
no double-peaked emission line is present in strong radio quasars with
relativistic jets. For radio-quiet counterparts, slow outflows with Thomson
scattering depth ~0.2 can scatter sufficient photons to the line-emitting
regions. This model can therefore solve the energy budget problem for
double-peaked line emitters.


title: Mergers of Binary Compact Objects

abstract:
  We work out the effects of hypercritical accretion, which transfers mass from
the secondary to the primary (first-born) neutron star (NS) in a binary,
showing that the mass of the primary would end up 0.6 M_sun greater than the
secondary NS in contradiction with the very nearly equal masses of the two NS's
in binaries measured to date. We discuss that the primary NS evolves into a
low-mass black-hole (LMBH) due to the hypercritical accretion. Using a flat
distribution in the mass ratio q (q = M_secondary/M_primary), we calculated a
ratio of LMBH-NS and NS-NS systems to be 5, in rough agreement with
Pinsonneault and Stanek (2006). These authors emphasize the importance of
"twins", which we discuss. The two NS's in the twins would be close in mass and
further increase the number of mergings.


title:
New southern blue compact dwarf galaxies in the 2dF Galaxy Redshift
  Survey

abstract:
  Aiming to find new extremely metal-deficient star-forming galaxies we
extracted from the Two-Degree Field Galaxy Redshift Survey (2dFGRS) 100K Data
Release 14 emission-line galaxies with relatively strong [OIII] 4363 emission.
Spectroscopic and photometric studies of this sample and, in addition, of 7
Tololo and 2 UM galaxies were performed on the basis of observations with the
ESO 3.6m telescope. All sample galaxies qualify with respect to their
photometric and spectroscopic properties as blue compact dwarf (BCD) galaxies.
Additionally, they show a good overlap with a comparison sample of 100
well-studied emission-line galaxies on the 12+log(O/H) vs. log(Ne/O), log(Ar/O)
and log(Fe/O) planes. From the analysis of the 2dFGRS subsample we report the
discovery of two new extremely metal-deficient BCDs with an oxygen abundance
12+log(O/H) < 7.6 and of another seven galaxies with 12+log(O/H) < 7.8.
Furthermore, we confirm previous oxygen abundance determinations for the BCDs
Tol 1304-353, Tol 2146-391, UM 559 and UM 570 to be 12+log(O/H) < 7.8.


title:
Correlations Between Central Massive Objects And Their Host Galaxies:
  From Bulgeless Spirals to Ellipticals

abstract:
  Recent observations by Ferrarese et al. (2006) and Wehner et al. (2006)
reveal that a majority of galaxies contain a central massive object (CMO),
either a supermassive black hole (SMBH) or a compact stellar nucleus,
regardless of the galaxy mass or morphological type, and that there is a tight
relation between the masses of CMOs and those of the host galaxies. Several
recent studies show that feedback from black holes can successfully explain the
$\msigma$ correlation in massive elliptical galaxies that contain SMBHs.
However, puzzles remain in spirals or dwarf spheroids that do not appear to
have black holes but instead harbor a compact central stellar cluster. Here we
use three-dimensional, smoothed particle hydrodynamics simulations of isolated
galaxies to study the formation and evolution of CMOs in bulgeless disk
galaxies, and simulations of merging galaxies to study the transition of the
CMO--host mass relation from late-type bulgeless spirals to early-type
ellipticals. Our results suggest that the observed correlations may be
established primarily by the depletion of gas in the central region by
accretion and star-formation, and may hold for all galaxy types. A systematic
search for CMOs in the nuclei of bulgeless disk galaxies would offer a test of
this conclusion. (Abridged)


title:
CADIS has seen the Virgo overdensity and parts of the Monoceros and
  `Orphan' streams in retrospect

abstract:
  We reanalyze deep star counts in five CADIS fields. The data are presented as
vertical density distributions of stars perpendicular to the Galactic plane. In
three fields the profiles are consistent with each other, while in two fields
significant overdensities of stars are found. The overdensity in one field can
be associated with the Virgo overdensity which can be traced right into the
disk of the Milky Way. Using this detection we estimate the mass of the Virgo
overdensity and show that this is equivalent to the stellar content of a Local
Group dwarf spheroidal galaxy. The overdensity in the second field is more
difficult to associate with a previously known overdensity. We suggest that it
is related both to the Monoceros stream and the recently discovered Orphan
stream.


title: Kinematic Structure of Merger Remnants

abstract:
  We use numerical simulations to study the kinematic structure of remnants
formed from mergers of equal-mass disk galaxies. In particular, we show that
remnants of dissipational mergers, which include the radiative cooling of gas,
star formation, feedback from supernovae, and the growth of supermassive black
holes, are smaller, rounder, have, on average, a larger central velocity
dispersion, and show significant rotation compared to remnants of
dissipationless mergers. The increased rotation speed of dissipational remnants
owes its origin to star formation that occurs in the central regions during the
galaxy merger. We have further quantified the anisotropy, three-dimensional
shape, minor axis rotation, and isophotal shape of each merger remnant, finding
that dissipational remnants are more isotropic, closer to oblate, have the
majority of their rotation along their major axis, and are more disky than
dissipationless remnants. Individual remnants display a wide variety of
kinematic properties. A large fraction of the dissipational remnants are oblate
isotropic rotators. Many dissipational, and all of the dissipationless, are
slowly rotating and anisotropic. The remnants of gas-rich major mergers can
well-reproduce the observed distribution of projected ellipticities, rotation
parameter (V/\sigma)*, kinematic misalignments, Psi, and isophotal shapes. The
dissipationless remnants are a poor match to this data. Our results support the
merger hypothesis for the origin of low-luminosity elliptical galaxies provided
that the progenitor disks are sufficiently gas-rich, however our remnants are a
poor match to the bright ellipticals that are slowly rotating and uniformly
boxy.


title:
The Discovery of a Neutron Star with a Spin Frequency of 530 Hz in
  A1744-361

abstract:
  We report the detection with the Rossi X-ray Timing Explorer (RXTE)
Proportional Counter Array (PCA) of 530 Hz burst oscillations in a
thermonuclear (type I) burst from the transient X-ray source A1744-361. This is
only the second burst ever observed from this source, and the first to be seen
in any detail. Our results confirm that A1744-361 is a low mass X-ray binary
(LMXB) system harboring a rapidly rotating neutron star. The oscillations are
first detected along the rising edge of the burst, and they show evidence for
frequency evolution of a magnitude similar to that seen in other burst sources.
The modulation amplitude and its increase with photon energy are also typical
of burst oscillations. The lack of any strong indication of photospheric radius
expansion during the burst suggests a 9 kpc upper limit of the source distance.
We also find energy dependent dips, establishing A1744-361 as a high
inclination, dipping LMXB. The timescale between the two episodes of observed
dips suggests an orbital period of ~ 97 minutes. We have also detected a 2 - 4
Hz quasi-periodic-oscillation (QPO) for the first time from this source. This
QPO appears consistent with ~ 1 Hz QPOs seen from other high-inclination
systems. We searched for kilohertz QPOs, and found a suggestive 2.3 sigma
feature at 800 Hz in one observation. The frequency, strength, and quality
factor are consistent with that of a lower frequency kilohertz QPO, but the
relatively low significance argues for caution, so we consider this a tentative
detection requiring confirmation.


title: Z-machines conference proceeding: Future continuum surveys

abstract:
  A significant population of distant sub-millimeter-selected galaxies (SMGs)
with powerful dust continuum emission that matches the luminosity of the
brightest QSOs and exceeds that of most extreme local galaxies detected by
IRAS, has been known for almost a decade. The full range of powerful ground-
and space-based facilities have been used to investigate them, and a good deal
of information about their properties has been gathered. This meeting addresses
some of the key questions for better understanding their properties. While
continuum detection is relatively efficient, a spectrum is always required both
to determine a distance/luminosity, and to probe astrophysics: excitation
conditions, the total mass, the mass distribution and degree of dynamical
relaxation. Once a redshift is known, then the associated stellar mass can be
found, and more specialized spectrographs can be used to search for specific
line diagnostics. The first generation of submm surveys, have yielded a
combined sample of several hundred SMGs. Here we discuss the size and follow-up
of future SMG samples that will be compiled in much larger numbers by
JCMT-SCUBA2, Herschel, Planck, LMT, ALMA, and a future large-aperture
(25-m-class) submm/far-IR wide-field ground-based telescope CCAT, planned to
operate at a Chilean site even better than ALMA's. The issues concerning
placing SMGs in the context of their environments and other populations of
high-redshift galaxies are discussed.


title:
Extracting first science measurements from the southern detector of the
  Pierre Auger observatory

abstract:
  The world's largest cosmic-ray detector is nearing completion in the remote
Pampas of Argentina. This instrument measures extensive air-showers with
energies from ${10^{18}-10^{20}}$ eV and beyond. A surface detector array of
area 3000 ${km^2}$ records the lateral distribution of charged particles at
ground level. A fluorescence detector overlooking the surface detector records
the longitudinal light profiles of showers in the atmosphere to make a
calorimetric energy measurement. A ``test beam'' for the fluorescence detector
is generated by a calibrated laser near the array center. This talk will focus
on detector characterizations essential to the first science results that have
been reported from the observatory. Plans to construct a larger instrument in
the northern hemisphere will also be outlined.


title: Photometric Redshifts in the IRAC Shallow Survey

abstract:
  Accurate photometric redshifts are calculated for nearly 200,000 galaxies to
a 4.5 micron flux limit of ~13 uJy in the 8.5 deg^2 Spitzer/IRAC Shallow
survey. Using a hybrid photometric redshift algorithm incorporating both
neural-net and template-fitting techniques, calibrated with over 15,000
spectroscopic redshifts, a redshift accuracy of \sigma = 0.06(1+z) is achieved
for 95% of galaxies at 0<z<1.5. The accuracy is \sigma = 0.12(1+z) for 95% of
AGN at 0<z<3. Redshift probability functions, central to several ongoing
studies of the galaxy population, are computed for the full sample. We
demonstrate that these functions accurately represent the true redshift
probability density, allowing the calculation of valid confidence intervals for
all objects. These probability functions have already been used to successfully
identify a population of Spitzer-selected high redshift (z>1) galaxy clusters.
We present one such spectroscopically confirmed cluster at <z>=1.24, ISCS
J1434.5+3427. Finally, we present a measurement of the 4.5 micron-selected
galaxy redshift distribution.


title:
Critical properties and stability of stationary solutions in
  multi-transonic pseudo-Schwarzschild accretion

abstract:
  For inviscid, rotational accretion flows, both isothermal and polytropic, a
simple dynamical systems analysis of the critical points has given a very
accurate mathematical scheme to understand the nature of these points, for {\em
any} pseudo-potential by which the flow may be driven on to a Schwarzschild
black hole. This allows for a complete classification of the critical points
for a wide range of flow parameters, and shows that the only possible critical
points for this kind of flow are saddle points and centre-type points. A
restrictive upper bound on the angular momentum of critical solutions has been
established. A time-dependent perturbative study reveals that the form of the
perturbation equation, for both isothermal and polytropic flows, is invariant
under the choice of any particular pseudo-potential. Under generically true
outer boundary conditions, the inviscid flow has been shown to be stable under
an adiabatic and radially propagating perturbtion. The perturbation equation
has also served the dual purpose of enabling an understanding of the acoustic
geometry for inviscid and rotational flows.


title:
The Arecibo Galaxy Environment Survey: Precursor Observations of the NGC
  628 group

abstract:
  The Arecibo Galaxy Environment Survey (AGES) is one of several HI surveys
utilising the new Arecibo L-band Feed Array (ALFA) fitted to the 305m radio
telescope at Arecibo. The survey is specifically designed to investigate
various galactic environments to higher sensitivity, higher velocity resolution
and higher spatial resolution than previous fully sampled, 21 cm multibeam
surveys. The emphasis is on making detailed observations of nearby objects
although the large system bandwidth (100 MHz) will allow us to quantify the HI
properties over a large instantaneous velocity range.
  In this paper we describe the survey and its goals and present the results
from the precursor observations of a 5 degree x 1 degree region containing the
nearby (~10 Mpc) NGC 628 group. We have detected all the group galaxies in the
region including the low mass (M{HI}~10^7Mo) dwarf, dw0137+1541 (Briggs, 1986).
The fluxes and velocities for these galaxies compare well with previously
published data. There is no intra-group neutral gas detected down to a limiting
column density of 2x10^{18}cm^{-2}. In addition to the group galaxies we have
detected 22 galaxies beyond the NGC 628 group, 9 of which are previously
uncatalogued.(Abridged)


title: Physics of accretion flows around compact objects

abstract:
  Several physical and astrophysical problems related to accretion onto black
holes and neutron stars are shortly reviewed. I discuss the observed
differences between these two types of compact objects in quiescent Soft X-ray
Transients. Then I review the status of various non-standard objects suggested
as an alternative to black-holes. Finally I present new results and suggestions
about the nature of the jet activity in Active Galactic Nuclei. {To cite this
article: J.-P. Lasota, C. R. Physique 6 (2006).}


title:
The DEEP2 Galaxy Redshift Survey: Clustering of Quasars and Galaxies at
  z=1

abstract:
  We present the clustering of DEEP2 galaxies at 0.7<z<1.4 around quasars
identified using both the SDSS and DEEP2 surveys. We measure the two-point
cross-correlation of a sample of 36 optically-selected,
spectroscopically-identified quasars from the SDSS and 16 more found in the
DEEP2 survey with the full DEEP2 galaxy sample over scales 0.1 < r_p < 10
Mpc/h. The clustering amplitude is found to be similar to the auto-correlation
function of DEEP2 galaxies, with a relative bias of b=0.89 +/-0.24 between
quasars and DEEP2 galaxies at z~1. No significant dependence is found on scale,
quasar luminosity, or redshift over the ranges we probe here. The clustering
amplitude errors are comparable to those from significantly larger quasar
samples, such as the 2dF QSO Redshift Survey. This results from the statistical
power of cross-correlation techniques, which exploit the fact that galaxies are
much more numerous than quasars. We also measure the local environments of
quasars using the 3rd-nearest-neighbor surface density of surrounding DEEP2
galaxies. Quasars are found in regions of similar mean overdensity as blue
DEEP2 galaxies; they differ in environment from the red DEEP2 galaxy population
at 2 sigma significance. Our results imply that quasars do not reside in
particularly massive dark matter halos at these redshifts, with a mean dark
matter halo mass of M_200 ~ 3 10^12 solar masses in a concordance LCDM
cosmology.


title:
Ejection of Hyper-Velocity Stars from the Galactic Centre by
  Intermediate-Mass Black Holes

abstract:
  We have performed N-body simulations of the formation of hyper-velocity stars
(HVS) in the centre of the Milky Way due to inspiralling intermediate-mass
black holes (IMBHs). We considered IMBHs of different masses, all starting from
circular orbits at an initial distance of 0.1 pc.
  We find that the IMBHs sink to the centre of the Galaxy due to dynamical
friction, where they deplete the central cusp of stars. Some of these stars
become HVS and are ejected with velocities sufficiently high to escape the
Galaxy. Since the HVS carry with them information about their origin, in
particular in the moment of ejection, the velocity distribution and the
direction in which they escape the Galaxy, detecting a population of HVS will
provide insight in the ejection processes and could therefore provide indirect
evidence for the existence of IMBHs.
  Our simulations show that HVS are generated in short bursts which last only a
few Myrs until the IMBH is swallowed by the supermassive black hole (SMBH). HVS
are ejected almost isotropically, which makes IMBH induced ejections hard to
distinguish from ejections due to encounters of stellar binaries with a SMBH.
After the HVS have reached the galactic halo, their escape velocities correlate
with the distance from the Galactic centre in the sense that the fastest HVS
can be found furthest away from the centre. The velocity distribution of HVS
generated by inspiralling IMBHs is also nearly independent of the mass of the
IMBH and can be quite distinct from one generated by binary encounters.
  Finally, our simulations show that the presence of an IMBH in the Galactic
centre changes the stellar density distribution inside r<0.02 pc into a core
profile, which takes at least 100 Myrs to replenish.


title: The formation of higher-order hierarchical systems in star clusters

abstract:
  We simulate open clusters containing up to 182 stars initially in the form of
singles, binaries and triples. Due to the high interaction rate a large number
of stable quadruples, quintuples, sextuples, and higher-order hierarchies form
during the course of the simulations. For our choice of initial conditions, the
formation rate of quadruple systems after about 2 Myr is roughly constant with
time at $\sim 0.008$ per cluster per Myr. The formation rate of quintuple and
sextuple systems are about half and one quarter, respectively, of the quadruple
formation rate, and both rates are also approximately constant with time. We
present reaction channels and relative probabilities for the formation of
persistent systems containing up to six stars. The reaction networks for the
formation and destruction of quintuple and sextuple systems can become quite
complicated, although the branching ratios remain largely unchanged during the
course of the cluster evolution. The total number of quadruples is about a
factor of three smaller than observed in the solar neighbourhood.


title: Eruptive Mass Loss in Very Massive Stars and Population III Stars

abstract:
  I discuss the role played by short-duration eruptive mass loss in the
evolution of very massive stars. Giant eruptions of Luminous Blue Variables
(LBVs) like the 19th century event of eta Carinae can remove large quantities
of mass almost instantaneously, making them significant in stellar evolution.
They can potentially remove much more mass from the star than line-driven
winds, especially if stellar winds are highly clumped such that previous
estimates of O star mass-loss rates need to be revised downward. When seen in
other galaxies as ``supernova impostors'', these LBV eruptions typically last
for less than a decade, and they can remove of order 10 Msun as indicated by
massive nebulae around LBVs. Such extreme mass-loss rates cannot be driven by
radiation pressure on spectral lines, because the lines will completely
saturate during the events. Instead, these outbursts must either be
continuum-driven super-Eddington winds or outright hydrodynamic explosions,
both of which are insensitive to metallicity. As such, this eruptive mode of
mass loss could also play a pivotal role in the evolution and ultimate fate of
massive metal-poor stars in the early universe. If they occur in these
Population III stars, such eruptions would also profoundly affect the chemical
yield and types of remnants from early supernovae and hypernovae thought to be
the origin of long gamma ray bursts.


title: Modified-Source Gravity and Cosmological Structure Formation

abstract:
  One way to account for the acceleration of the universe is to modify general
relativity, rather than introducing dark energy. Typically, such modifications
introduce new degrees of freedom. It is interesting to consider models with no
new degrees of freedom, but with a modified dependence on the conventional
energy-momentum tensor; the Palatini formulation of $f(R)$ theories is one
example. Such theories offer an interesting testing ground for investigations
of cosmological modified gravity. In this paper we study the evolution of
structure in these ``modified-source gravity'' theories. In the linear regime,
density perturbations exhibit scale dependent runaway growth at late times and,
in particular, a mode of a given wavenumber goes nonlinear at a higher redshift
than in the standard $\Lambda$CDM model. We discuss the implications of this
behavior and why there are reasons to expect that the growth will be cut off in
the nonlinear regime. Assuming that this holds in a full nonlinear analysis, we
briefly describe how upcoming measurements may probe the differences between
the modified theory and the standard $\Lambda$CDM model.


title: Proper Motion of Pulsar B1800-21

abstract:
  We report high angular resolution, multi-epoch radio observations of the
young pulsar PSR B1800-21. Using two pairs of data sets, each pair spanning
approximately a ten year period, we calculate the proper motion of the pulsar.
We obtain a proper motion of mu_alpha=11.6 +- 1.8 mas/yr, mu_delta=14.8 +- 2.3
mas/yr, which clearly indicates a birth position at the extreme edge of the W30
supernova remnant. Although this does not definitively rule out an association
of W30 and PSR B1800-21, it does not support an association.


title: Parameters and Winds of Hot Massive Stars

abstract:
  Over the last years a new generation of model atmosphere codes, which include
the effects of metal line-blanketing of millions of spectral lines in NLTE, has
been used to re-determine the properties of massive stars through quantitative
spectral analysis methods applied to optical, IR and UV spectra. This has
resulted in a significant change of the effective temperature scale of early
type stars and a revision of mass-loss rates. Observed mass-loss rates and
effective temperatures depend strongly on metallicity, both in agreement with
theoretical predictions. The new model atmospheres in conjunction with the new
generation of 10m-class telescopes equipped with efficient multi-object
spectrographs have made it possible to study blue supergiants in galaxies far
beyond the Local Group in spectroscopic detail to determine accurate chemical
composition, extinction and distances. A new distance determination method, the
flux weighted gravity - luminosity relationship, is discussed as a very
promising complement to existing stellar distance indicators.
  Observationally, there are still fundamental uncertainties in the
determination of stellar mass-loss rates, which are caused by the fact that
there is evidence that the winds are inhomogeneous and clumped. This may lead
to major revisions of the observed rates of mass-loss.


title:
Star Cluster Ecology: VII The evolution of young dense star clusters
  containing primordial binaries

abstract:
  We study the first 100Myr of the evolution of isolated star clusters
initially containing 144179 stars, including 13107 (10%) primordial hard
binaries. Our calculations include the effects of both stellar and binary
evolution. Gravitational interactions among the stars are computed by direct
N-body integration using high precision GRAPE-6 hardware. The evolution of the
core radii and central concentrations of our simulated clusters are compared
with the observed sample of young (about 100Myr) star clusters in the large
Magellanic cloud. Even though our simulations start with a rich population of
primordial binaries, core collapse during the early phase of the cluster
evolution is not prevented. Throughout the simulations, the fraction of
binaries remains roughly constant (about 10%). Due to the effects of mass
segregation the mass function of intermediate-mass main-sequence stars becomes
as flat as $\alpha=-1.8$ in the central part of the cluster (where the initial
Salpeter mass function had $\alpha=-2.35$). About 6--12% of the neutron stars
were retained in our simulations; the fraction of retained black holes is
40--70%. In each simulation about three neutron stars become members of close
binaries with a main-sequence companion. Such a binary will eventually become
an x-ray binary, when the main-sequence star starts to fill its Roche lobe.
Black holes are found more frequently in binaries; in each simulated cluster we
find about 11 potential x-ray binaries containing a black hole. Abstract
abbreviated....


title:
Stellar model atmospheres with magnetic line blanketing. III. The role
  of magnetic field inclination

abstract:
  Context. See abstract in the paper.
  Aims. In the last paper of this series we study the effects of the magnetic
field, varying its strength and orientation, on the model atmosphere structure,
the energy distribution, photometric colors and the hydrogen Balmer line
profiles. We compare with the previous results for an isotropic case in order
to understand whether there is a clear relation between the value of the
magnetic field angle and model changes, and to study how important the
additional orientational information is. Also, we examine the probable
explanation of the visual flux depressions of the magnetic chemically peculiar
stars in the context of this work.
  Methods. We calculated one more grid of the model atmospheres of magnetic A
and B stars for different effective temperatures (Teff=8000K, 11000K, 15000K),
magnetic field strengths (B=0, 5, 10, 40 kG) and various angles of the magnetic
field (Omega=0-90 degr) with respect to the atmosphere plane. We used the
LLmodels code which implements a direct method for line opacity calculation,
anomalous Zeeman splitting of spectral lines, and polarized radiation transfer.
  Results. We have not found significant changes in model atmosphere structure,
photometric and spectroscopic observables or profiles of hydrogen Balmer lines
as we vary the magnetic field inclination angle Omega. The strength of the
magnetic field plays the main role in magnetic line blanketing. We show that
the magnetic field has a clear relation to the visual flux depressions of the
magnetic CP stars.
  Conclusions. See abstract in the paper.


title: Modeling Galaxy Clustering with Cosmological Simulations

abstract:
  I review recent progress in understanding and modeling galaxy clustering in
cosmological simulations, with emphasis on models based on high-resolution
dissipationless simulations. During the last decade, significant advances in
our understanding of abundance and clustering of dark matter halos allowed
construction of accurate, quantitative models of galaxy clustering both in
linear and non-linear regimes. Results of several recent studies show that
dissipationless simulations with a simple, non-parametric model for the
relation between halo circular velocity and luminosity of the galaxy they host
predict the shape, amplitude, and luminosity dependence of the two-point
correlation function in excellent agreement with the observed galaxy clustering
in the SDSS data at z~0 and in the DEEP2 samples at z~1 over the entire probed
range of projected separations. In particular, the small-scale upturn of the
correlation function from the power-law form in the SDSS and DEEP2
luminosity-selected samples is reproduced very well. At z~3-5, predictions also
match the observed shape and amplitude of the angular two-point correlation
function of Lyman-break galaxies (LBGs) on both large and small scales,
including the theoretically predicted strong upturn at small scales. This
suggests that, like galaxies in lower redshift samples, the LBGs are fair
tracers of the overall halo population and that their luminosity is tightly
correlated with the circular velocity (and hence mass) of their dark matter
halos.


title:
Evolution of linear perturbations through a bouncing world model: Is the
  near Harrison-Zel'dovich spectrum possible via a bounce?

abstract:
  We present a detailed numerical study of the evolutions of cosmological
linear perturbations through a simple bouncing world model based on two scalar
fields. We properly identify the relatively growing and decaying solutions in
expanding and collapsing phases. Using a decomposition based on the large-scale
limit exact solution of curvature (adiabatic) perturbations with two
independent modes, we assign the relatively growing/decaying one in an
expanding phase as the C/d-mode. In the collapsing phase, the roles are
reversed, and the C/d-mode is relatively decaying/growing. The analytic
solution shows that, as long as the large scale and the adiabatic conditions
are met, the C- and d-modes preserve their nature throughout the bounce. Here,
by using a concrete nonsingular bouncing world model based on two scalar
fields, we numerically follow the evolutions of the correctly identified C- and
d-modes which preserve their nature through the bounce, thus confirming our
previous anticipation based on the analytic solution. Thus, while the
large-scale condition is satisfied and the adiabatic condition is met during
the bounce, we conclude that it is not possible to obtain the near
Harrison-Zel'dovich scale-invariant density spectrum through a bouncing world
model as long as the seed fluctuations were generated from quantum fluctuations
of the curvature perturbation in the collapsing phase.


title: Color-magnitude relations of late-type galaxies

abstract:
  We use a large sample of galaxies drawn from the Sloan Digital Sky Survey
(SDSS) and Two Micro All Sky Survey (2MASS) to present Color-Magnitude
Relations (CMRs) for late-type galaxies in both optical and optical-infrared
bands. A sample from SDSS Data Release 4 (DR4) is selected to investigate the
optical properties. Optical-infrared colors are estimated from a position
matched sample of DR4 and 2MASS, in which the photometric aperture mismatch
between these two surveys is carefully corrected. It is shown that, after
correcting the dust attenuation, the optical colors for faint galaxies (i.e.
$M_r > -21$) have very weak correlation with the luminosity, while the optical
colors for bright galaxies (i.e. $M_r < -21$) are redder for more luminous
galaxies. All (optical, optical-infrared and infrared) colors show similar but
stronger correlations with stellar mass than with absolute magnitude. The
optical colors correlate more strongly with stellar mass surface density than
with stellar mass, while optical-infrared and infrared colors show stronger
correlations with stellar mass. By comparing the observed colors of our sample
galaxies with the colors predicted by stellar population synthesis model, we
find that massive late-type galaxies have older and higher metallicity stellar
population than less massive galaxies. This suggests that CMRs for late-type
galaxies are trends defined by the combination of stellar mean age and
metallicity. Moreover, our results suggest that the stellar mean metallicity of
late-type galaxy is mainly determined by its stellar mass, while the star
formation history is mainly regulated by the stellar mass surface density.


title:
Broad H-alpha wings from the optically thin stellar wind of the hot
  components in symbiotic binaries

abstract:
  Aims: To model broad H-alpha wings observed in symbiotic binaries by an
optically thin, bipolar stellar wind from their hot components as an
alternative to that considering the Raman scattering of Ly-beta photons on
atomic hydrogen. Methods: Profile-fitting analysis. Comparison of the observed
broad H-alpha wings and their luminosity with those predicted by the model.
Results: Synthetic H-alpha profiles fit excellently the observed wings for |RV|
> 200 km/s in our sample of 10 symbiotic stars during the quiescent as well as
active phases. The wing profile formed in the stellar wind can be approximated
by a function f(RV) proportional to RVexp-2, which is of the same type as that
arising from the Raman scattering. Therefore it is not possible to distinguish
between these two processes only by modeling the line profile. Some
observational characteristics of the H-alpha emission suggest the ionized
stellar wind from the hot component to be the dominant source contributing to
the H-alpha wings during active phases. The model corresponding mass-loss rates
from the hot components are of a few x 10exp(-8) M(Sun)/yr and of a few x
(10exp(-7) - 10exp(-6)) M(Sun)/yr during quiescent and active phases,
respectively.


title:
An Eccentric Circumbinary Accretion Disk and the Detection of Binary
  Massive Black Holes

abstract:
  We present a two-dimensional grid-based hydrodynamic simulation of a thin,
viscous, locally-isothermal corotating disk orbiting an equal-mass Newtonian
binary point mass on a fixed circular orbit. We study the structure of the disk
after multiple viscous times. The binary maintains a central hole in the
viscously-relaxed disk with radius equal to about twice the binary semimajor
axis. Disk surface density within the hole is reduced by orders of magnitude
relative to the density in the disk bulk. The inner truncation of the disk
resembles the clearing of a gap in a protoplanetary disk. An initially circular
disk becomes elliptical and then eccentric. Disturbances in the disk contain a
component that is stationary in the rotating frame in which the binary is at
rest; this component is a two-armed spiral density wave. We measure the
distribution of the binary torque in the disk and find that the strongest
positive torque is exerted inside the central low-density hole. We make
connection with the linear theory of disk forcing at outer Lindblad resonances
(OLRs) and find that the measured torque density distribution is consistent
with forcing at the 3:2 (m=2) OLR, well within the central hole. We also
measure the time dependence of the rate at which gas accretes across the hole
and find quasi-periodic structure. We discuss implications for variability and
detection of active galactic nuclei containing a binary massive black hole.


title:
Dynamical properties of Ultraluminous Infrared Galaxies. II. Traces of
  dynamical evolution and end products of local ultraluminous mergers

abstract:
  We present results from our Very Large Telescope large program to study the
dynamical evolution of local Ultraluminous Infrared Galaxies (ULIRGs) and QSOs.
This paper is the second in a series presenting the stellar kinematics of 54
ULIRGs, derived from high resolution, long-slit H- and K-band spectroscopy. The
data presented here, including observations of 17 new targets, are mainly
focused on sources that have coalesced into a single nucleus. The stellar
kinematics, extracted from the CO ro-vibrational bandheads in our spectra,
indicate that ULIRG remnants are dynamically heated systems with a mean
dispersion of 161 km/s. The combination of kinematic, structural, and
photometric properties of the remnants indicate that they mostly originate from
major mergers and that they result in the formation of systems supported by
random motions, therefore, elliptical galaxies. The peak of the velocity
dispersion distribution and the locus of ULIRGs on the fundamental plane of
early-type galaxies indicate that the end products of ultraluminous mergers are
typically moderate-mass ellipticals (of stellar mass ~10^10 - 10^11 M_sun).
Converting the host dispersion into black hole mass with the aid of the
M_BH-sigma relation yields black hole mass estimates of the order 10^7 - 10^8
M_sun and high accretion rates with Eddington efficiencies often >0.5.


title: Polarized synchrotron emission

abstract:
  Galactic synchrotron emission represents the most relevant foreground
contamination in cosmic microwave background (CMB) anisotropy observations at
angular scales $\theta \gsim 1^\circ$ and frequencies $\nu \lsim 70$ GHz. The
accurate understanding of its polarization properties is crucial to extract the
cosmological information contained in the CMB polarization anisotropy. Radio
surveys at $\nu \sim 1$ GHz offer the unique opportunity to study Galactic
synchrotron emission where it represents the dominant component, possibly
except for regions close to the Galactic plane where free-free emission is also
important. We review the observational status of Galactic radio surveys at
scales $\theta \gsim 0.5^\circ$. Leiden surveys, thanks to their frequency
coverage from 0.408 GHz to 1.411 GHz, still remain of fundamental importance
for the comprehension of depolarization phenomena. Recent surveys at 1.42 GHz
(in both total intensity and polarization) with a better sensitivity and sky
sampling now cover both celestial hemispheres and allow to accurately map the
correlation properties of the diffuse synchrotron emission. We present an
analysis of these surveys in terms of angular power spectrum. A comparison of a
simple frequency extrapolation of these results with the recent WMAP results
shows that we are close to map the bulk of the diffuse synchrotron polarization
fluctuations and to understand the corresponding implications for CMB
experiments.


title:
Young stars in the Galactic Centre: a potential intermediate-mass star
  origin

abstract:
  There has been recent speculation (Davies & King 2005) that the cores of
intermediate-mass stars stripped of their envelopes by tidal interaction with
the supermassive black hole in the Galactic centre could form a population
observationally similar to the so-called Sgr A* cluster or `S' stars, which
have close eccentric orbits around the hole. We model the evolution of such
stars, and show that the more luminous end of the population may indeed appear
similar to young B stars within the observational limits of the Galactic Centre
region. Whether some or all of these cluster stars can be accounted for in this
manner depends strongly on the assumed IMF of the loss cone stars and the
scattering rate. If most of the observed stars are in fact scattered from the
Galactic Centre inner cusp region itself then the population of ~20 to current
observational limits may be reproduced. However, this only works if the local
relaxation time is small and relies on the cusp stars themselves being young,
i.e. it is dependent on some star formation being possible in the central few
parsecs. Conversely, we obtain a possible constraint on the tidal stripping
rate of `normal'-IMF stars if there are not to be red stars visible in the Sgr
A* cluster.


title: Multi-wavelength afterglow observations of the high redshift GRB 050730

abstract:
  GRB 050730 is a long duration high-redshift burst (z=3.967) discovered by
Swift. The afterglow shows variability and is well monitored over a wide
wavelength range. We present comprehensive temporal and spectral analysis of
the afterglow of GRB 050730 including observations from the millimeter to
X-rays. We use multi-wavelength afterglow data to understand the temporal and
spectral decay properties with superimposed variability of this high redshift
burst. Five telescopes were used to study the decaying afterglow of GRB 050730
in the B, V, r', R, i', I, J and K photometric pass bands. A spectral energy
distribution was constructed at 2.9 hours post-burst in the K, J, I, R, V and B
bands. X-ray data from the satellites Swift and XMM-Newton were used to study
the afterglow evolution at higher energies. The early afterglow shows
variability at early times and shows a steepening at ~0.1 days (8.6 ks) in the
B, V, r', R, i', I, J and K passbands. The early afterglow light curve decayed
with alpha_1 = -0.60+/-0.07 and alpha_2 = -1.71+/-0.06 based on R and I band
data. A millimeter detection of the afterglow around 3 days after the burst
shows an excess in comparison to predictions. The early X-ray light curve
observed by Swift is complex and contains flares. At late times the X-ray light
curve can be fit by a powerlaw alpha_x = -2.5+/-0.15 which is steeper than the
optical light curve. A spectral energy distribution (SED) was constructed at
\~2.9 hours after the burst. An electron energy index, p, of ~ 2.3 was
calculated using the SED and the photon index from the X-ray afterglow spectra
and indicates that the synchrotron cooling frequency nu_c is above observed
frequencies.


title:
Discovery and analysis of three faint dwarf galaxies and a globular
  cluster in the outer halo of the Andromeda galaxy

abstract:
  We present the discovery of three faint dwarf galaxies and a globular cluster
in the halo of the Andromeda galaxy (M31), found in our MegaCam survey that
spans the southern quadrant of M31, from a projected distance of ~50 kpc to
\~150 kpc. Though the survey covers 57 sq. degrees, the four satellites lie
within 2\deg of one another. We estimate that the globular cluster lies at a
total distance of 175+/-55 kpc from M31, making it the farthest M31 globular
cluster known. It also shows the typical characteristics of a bright globular
cluster, with a half-light radius of 2.3+/-0.2 pc and an absolute magnitude in
the V band of M_{V,0}=-8.5+/-0.3 and contains a very old population with a
metallicity of [Fe/H]~-1.3. The three dwarf galaxies are all very faint, with
absolute magnitudes in the range -7.3<M_{V,0}<-6.4, and show strikingly similar
characteristics with metallicities of [Fe/H]~-1.4 and half-light radii of
\~120+/-45 pc, making these dwarf galaxies two to three times smaller than the
smallest previously known satellites of M31. We estimate them to be between 740
and 955 kpc from the Sun. Extrapolating from the coverage of the survey, we
estimate that up to 45+/-20 satellites brighter than M_V~-6.5 should be
orbiting M31. Hence faint dwarf galaxies cannot alone account for the missing
satellites that are predicted by $\Lambda$CDM models, unless they reside in
dark matter mini-halos that are more massive than the typical masse of 10^7
solar masses currently inferred from their central radial velocity dispersion.
(abridged)


title:
20-100 keV properties of cataclysmic variables detected in the
  INTEGRAL/IBIS survey

abstract:
  Analysis of INTEGRAL/IBIS survey observations has revealed that the rare
intermediate polar and asynchronous polar cataclysmic variables are
consistently found to emit in the 20-100 keV energy band, whereas synchronous
polars and the common non-magnetic CVs rarely do so. From the correlation of a
candidate INTEGRAL/IBIS survey source list with a CV catalogue, 15 CV
detections by IBIS have been established including a new INTEGRAL source IGR
J06253+7334. The properties of these sources and 4 additional CV candidates are
discussed in the context of their 20-100 keV emission characteristics and we
conclude that the INTEGRAL mission is an important tool in the detection of new
magnetic CV systems. Furthermore, analysis of the time-averaged spectra of CVs
detected by INTEGRAL indicate that although there is little difference between
the spectral slopes of the different sub-types, intermediate polars may be
considerably more luminous than polars in the soft gamma-ray regime. We also
present the detection of an unusual high-energy burst from V1223 Sgr discovered
by inspection of the IBIS light-curve. Additionally, we have compared the IBIS
and optical AAVSO light-curves of SS Cyg and extracted IBIS spectra during
single periods of optical outburst and quiescence. We find that the 20-100 keV
flux is an order of magnitude greater during optical quiescence. This is in
agreement with previous studies which show that the hard X-ray component of SS
Cyg is suppressed during high accretion states


title:
An imaging survey of a uniform sample of Brightest Cluster Galaxies and
  Intracluster Light

abstract:
  We present deep, large area B and r' imaging for a sample of 49 brightest
cluster galaxies (BCGs). The clusters were selected by their x-ray luminosity
and redshift to form two volume limited samples, one with mean redshift ~ 0.07
and one at a mean redshift ~ 0.17. For each cluster the data cover 41' by 41'.
We discuss our data reduction techniques in detail, and show that we can
reliably measure the surface brightness at the levels of mu_B ~ 29 and mu_r' ~
28. For each galaxy we present the B and r' images together with the surface
brightness profile, B-r' colour, eccentricity and position angle as a function
of radius. We investigate the distribution of positional offsets between the
optical centroid of the BCG and the centre of the X-ray emission, and conclude
that the mass profiles are cuspy, and do not have extended cores. We also
introduce a method to objectively identify the transition from BCG to extended
envelope of intra-cluster light, using the Petrosian index as a function of
radius.


title:
RXTE Observations of 1A 1744-361: Correlated Spectral and Timing
  Behavior

abstract:
  We analyze Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array
(PCA) data of the transient low mass X-ray binary (LMXB) system 1A 1744-361. We
explore the X-ray intensity and spectral evolution of the source, perform
timing analysis, and find that 1A 1744-361 shows `atoll' behavior during the
outbursts. The color-color diagram indicates that this LMXB was observed in a
low intensity spectrally hard (low-hard) state and in a high intensity `banana'
state. The low-hard state shows a horizontal pattern in the color-color
diagram, and the previously reported `dipper QPO' appears only during this
state. We also perform energy spectral analyses, and report the first detection
of broad iron emission line and iron absorption edge from 1A 1744-361.


title:
Color-Magnitude Diagrams of Resolved Stars in Virgo Cluster Dwarf
  Galaxies

abstract:
  The Advanced Camera for Surveys (ACS) on HST has been used to image two
fields in the core of the Virgo cluster that contain a number of dwarf
elliptical galaxies. The combined F555W and F814W images have resolved red
giant stars in these galaxies, down to 1 mag below the giant branch tip. Two of
the galaxies were targeted because of their extremely low central surface
brightnesses (Bo > 27.0), thus the successful resolution into stars confirms
the existence of such tenuous galaxies. Red giant stars were also found that
are not ostensibly associated with any galaxy. Color-magnitude diagrams in V
and I have been derived and used to derive distances and metallicities via the
magnitude and mean color of the red giant branch tip. The mean abundances of
stars in the dwarfs range from -1.2 [Fe/H] < -2.4, and fall along the relation
between galaxy luminosity and metallicity found for Local Group and M81 group
dwarf ellipticals. The mean distance modulus of the six Virgo galaxies is 31.0
+/- 0.05, or 16.1 +/- 0.4 Mpc, whereas that for the intracluster stars in those
fields is 31.2 +/- 0.09 (17.4 +/- 0.7 Mpc).


title: Radio bubbles in the composite AGN-starburst galaxy NGC6764

abstract:
  We present multi-frequency radio continuum as well as HI observations of the
composite galaxy NGC6764, which has a young, circumnuclear starburst and also
harbours an active galactic nucleus (AGN). These observations have been made at
a number of frequencies ranging from ~600 MHz to 15 GHz using both the GMRT and
the VLA. They reveal the structure of the bipolar bubbles of non-thermal, radio
emission which are along the minor axis of the galaxy and extend up to ~1.1 and
1.5 kpc on the northern and southern sides respectively. Features in the radio
bubbles appear to overlap with filaments of H_alpha emission. The
high-resolution observations reveal a compact source, likely to be associated
with the nucleus of the galaxy, and a possible radio jet towards the
south-west. We have compiled a representative sample of galaxies with bubbles
of non-thermal radio emission and find that these are found in galaxies with an
AGN.
  The HI observations with the GMRT show two peaks of emission on both ends of
the stellar-bar and depletion of HI in the central region of the galaxy. We
also detect HI in absorption against the central radio peak at the systemic
velocity of the galaxy. The HI-absorption spectrum also suggests a possible
weak absorption feature blue-shifted by ~120 km/s, which requires confirmation.
A similar feature has also been reported from observations of CO in emission,
suggesting that the circumnuclear starburst and nuclear activity affect the
kinematics of the atomic and molecular gas components, in addition to the
ionised gas seen in H_alpha and [N II].


title:
A search for optical bursts from the rotating radio transient J1819-1458
  with ULTRACAM

abstract:
  We report on the search for optical bursts from J1819-1458, a member of the
recently discovered Rotating Radio Transients (RRATs). J1819-1458 exhibits 3
millisecond bursts with a peak flux at 1.4 GHz of 3.6 Jy every ~3.4 minutes,
implying that it is visible for only ~1 second per day at radio wavelengths.
Assuming that the optical light behaves in a similar manner, the most sensitive
way of detecting RRATs is hence not to take long exposures of the field, but
instead to capture individual bursts using a high-speed camera mounted on a
large aperture telescope. Using ULTRACAM on the 4.2-m William Herschel
Telescope (WHT) we obtained 97100 images of the field of J1819-1458, each of
18.1 milliseconds exposure time and with essentially no dead-time between the
frames. We find no evidence for bursts in u', g' and i' at magnitudes brighter
than 15.1, 17.4 and 16.6 (5 sigma), corresponding to fluxes of less than 3.3,
0.4 and 0.8 mJy at 3560A, 4820A and 7610A, respectively.


title: On the origin of the diffuse gamma-ray background radiation

abstract:
  We show that inverse Compton scattering of cosmic-microwave-background and
starlight photons by cosmic-ray electrons in the interstellar and intergalactic
space explains well the spectrum and intensity of the diffuse gamma-ray
background radiation (GBR), which was measured by EGRET aboard the Compton
Gamma Ray Observatory (CGRO) in directions away from the Galactic disk and
centre. The Gamma Ray Large Area Space Telescope (GLAST) will be able to
separate the Galactic foreground from the extragalactic gamma-rays, and to
provide stringent tests of the theory.


title:
Planetary Nebula Abundances and Morphology: Probing the Chemical
  Evolution of the Milky Way

abstract:
  This paper presents a homogeneous study of abundances in a sample of 79
northern galactic planetary nebulae whose morphological classes have been
uniformly determined. Ionic abundances and plasma diagnostics were derived from
selected optical line strengths in the literature, and elemental abundances
were estimated with the Ionization Correction Factor developed by Kingsbourgh &
Barlow (1994). We compare the elemental abundances to the final yields obtained
from stellar evolution models of low-and intermediate-mass stars, and we
confirm that most Bipolar planetary nebulae have high nitrogen and helium
abundance, and are the likely progeny of stars with main-sequence mass larger
than 3 solar masses. We derive <Ne/O>=0.27, and discuss the implication of such
a high ratio in connection with the solar neon abundance. We determine the
galactic gradients of oxygen and neon, and found Delta log (O/H)/Delta R=-0.01
dex/kpc$ and Delta log (Ne/H)/Delta R=-0.01 dex/kpc. These flat PN gradients do
not reconcile with galactic metallicity gradients flattening with time.


title:
CaII and DLA absorption line systems: dust, metals and star formation at
  0.4<z<1.3

abstract:
  Absorption line studies of galaxies along the line-of-sight to distant
quasars allow a direct observational link between the properties of the
extended gaseous disk/halo and of the star forming region of galaxies. In these
proceedings we review recent work on CaII absorbers detected in the SDSS at
0.4<z<1.3 which, because of their dust content and chemical properties, may lie
spatially closer to the central host galaxy than most DLAs. We present direct
evidence for the presence of star formation, through observation of the
[OII]3727,3730 emission line, in both CaII absorbers and MgII-selected Damped
Lyman-alpha (DLA) systems. The measured star formation rate (SFR) from light
falling within the SDSS fibre apertures (corresponding to physical radii of 6-9
h^{-1}kpc) is 0.11-0.48 Msol/yr for the CaII-absorbers and 0.11-0.14 Msol/yr
for the MgII-selected DLAs. The contribution of both CaII absorbers and DLAs to
the total observed SFR density, in the redshift range 0.4 < z < 1.3, is small,
<10%. Our result contrasts with recent conclusions, based on the Schmidt law,
that DLA absorbers can account for the majority of the total observed SFR
density in the same redshift range.


title: The evolution of galaxy groups and of galaxies therein

abstract:
  Properties of groups of galaxies depend sensitively on the algorithm for
group selection, and even the most recent catalogs of groups built from
redshift-space selection should suffer from projections and infalling galaxies.
The cosmo-dynamical evolution of groups from initial Hubble expansion to
collapse and virialization leads to a fundamental track (FT) in
virial-theorem-M/L vs crossing time. The increased rates of mergers, both
direct and after dynamical friction, in groups relative to clusters, explain
the higher fraction of elliptical galaxies at given local number density in
X-ray selected groups, relative to clusters, even when the hierarchical
evolution of groups is considered. Galaxies falling into groups and clusters
should later travel outwards to typically 2 virial radii, which is somewhat
less than the outermost radius where observed galaxy star formation
efficiencies are enhanced relative to field galaxies of same morphological
type. An ongoing analysis of the internal kinematics of X-ray selected groups
suggests that the radial profiles of line of sight velocity dispersion are
consistent with isotropic NFW distributions for the total mass density, with
higher (lower) concentrations than LambdaCDM predictions in groups of high
(low) mass. The critical mass, at M200 ~ 10^13 M_sun is consistent with
possible breaks in the X-ray luminosity-temperature and Fundamental Plane
relations. The internal kinematics of groups indicate that the M-T relation of
groups should agree with that extrapolated from clusters with no break at the
group scale. The analyses of observed velocity dispersion profiles and of the
FT both suggest that low velocity dispersion groups (compact and loose, X-ray
emitting or undetected) are quite contaminated by chance projections.


title: Three intervening galaxy absorbers towards GRB060418: faint and dusty?

abstract:
  We present an analysis of three strong, intervening Mg II absorption systems
(z_abs = 0.603, 0.656, 1.107) towards the optical afterglow of gamma-ray burst
(GRB) 060418. From high resolution UVES spectra we measure metal column
densities and find that the highest redshift absorber exhibits a large amount
of dust depletion compared with DLAs seen in QSO spectra. The intervening z_abs
= 1.107 absorber is also unusual in exhibiting a clear 2175 A bump, the first
time this feature has been definitively detected in a GRB spectrum. The GRB
afterglow spectrum is best fit with a two component extinction curve: an SMC
extinction law at z=1.49 (the redshift of the host) with E(B-V) = 0.07+-0.01
and a Galactic extinction curve at z ~ 1.1 with E(B-V) = 0.08+-0.01. We also
present a moderately deep NTT R-band image of the GRB060418 field and
spectroscopy of four galaxies within 1 arcminute. None of these objects has a
redshift that matches any of the intervening absorbers, and we conclude that
the galaxies responsible for the two intervening Mg II absorbers at z ~ 0.6
have luminosities ~<0.3 L^star.


title:
Is there a chance that the anisotropies in the cosmic microwave
  background detected by COBE are an artefact of COBE's image reconstruction?

abstract:
  The COBE time ordered data (TOD) was reanalysed for anisotropies in the
cosmic microwave background with a novel technique that is much simpler and
more robust than used in the official analysis of the COBE TOD. The technique
extends the statistical concept of rejecting the null hypothesis to image
reconstruction by asking if the TOD is consistent with no anisotropies outside
the galactic band. If it is assumed that the instrumentation noise is ideal, as
appears to be the case in the official analysis, the null hypothesis can be
rejected to 28 sigma, a highly significant detection. However, the official
analysis presents no information supporting the ideal noise assumption to the
level required to reject the null hypothesis. The interaction of COBE's
calibration error of roughly 3.0% with the brightest regions of the galactic
band in combination with the reconstruction algorithm may have introduced
artefacts roughly of the size and spectral signature of the 10ppm anisotropies
reported by COBE. Data from follow up missions have similar problems with
calibration errors that may have resulted in similar sky maps to COBE. It is
pointed out that either a few hours of repetitive circular scans using the WMAP
satellite or the single beam antenna of the soon-to-be-launched Planck
satellite should provide definitive evidence as to the existence or non
existence of the 10ppm anisotropies without the use of image reconstruction.


title: Low energy bounds on Poincare violation in causal set theory

abstract:
  In the causal set approach to quantum gravity, Poincar\'{e} symmetry is
modified by swerving in spacetime, induced by the random lattice discretization
of the space-time structure. The broken translational symmetry at short
distances is argued to lead to a residual diffusion in momentum space, whereby
a particle can acquire energy and momentum by drift along its mass shell and a
system in equilibrium can spontaneously heat up. We consider bounds on the rate
of momentum space diffusion coming from astrophysical molecular clouds, nuclear
stability and cosmological neutrino background. We find that the strongest
limits come from relic neutrinos, which we estimate to constrain the momentum
space diffusion constant by $k < 10^{-61} {\rm GeV}^3$ for neutrinos with
masses $m_\nu > 0.01 {\rm eV}$, improving the previously quoted bounds by
roughly 17 orders of magnitude.


title:
An XMM-Newton view of the young open cluster NGC 6231 -- II. The OB star
  population

abstract:
  In this second paper, we pursue the analysis of the 180 ks XMM-Newton
campaign towards the young open cluster NGC 6231 and we focus on its rich OB
star population. We present a literature-based census of the OB stars in the
field of view with more than one hundred objects, among which 30% can be
associated with an X-ray source. All the O-type stars are detected in the X-ray
domain as soft and reasonably strong emitters. In the 0.5-10.0 keV band, their
X-ray luminosities scale with their bolometric luminosities as $\log
L_\mathrm{X} - \log L_\mathrm{bol}=-6.912\pm0.153$. Such a scaling law holds in
the soft (0.5-1.0 keV) and intermediate (1.0-2.5 keV) bands but breaks down in
the hard band. While the two colliding wind binaries in our sample clearly
deviate from this scheme, the remaining O-type objects show a very limited
dispersion (40% or 20% according to whether `cool' dwarfs are included or not),
much smaller than that obtained from previous studies. At our detection
threshold and within our sample, the sole identified mechanism that produces
significant modulations in the O star X-ray emission is related to wind
interaction. The intrinsic X-ray emission of non-peculiar O-type stars seems
thus constant for a given star and the level of its X-ray emission is
accurately related to the its luminosity or, equivalently, to its wind
properties. Among B-type stars, the detection rate is only about 25% in the
sub-type range B0-B4 and remains mostly uniform throughout the different
sub-populations while it drops significantly at later sub-types. The associated
X-ray spectra are harder than those of O-type stars. Our analysis points
towards the detected emission being associated with a physical PMS companion
>... [see paper for the complete abstract]


title: CMB quadrupole suppression: II. The early fast roll stage

abstract:
  Within the effective field theory of inflation, an initialization of the
classical dynamics of the inflaton with approximate equipartition between the
kinetic and potential energy of the inflaton leads to a brief fast roll stage
that precedes the slow roll regime. The fast roll stage leads to an attractive
potential in the wave equations for the mode functions of curvature and tensor
perturbations. The evolution of the inflationary perturbations is equivalent to
the scattering by this potential and a useful dictionary between the scattering
data and observables is established.Implementing methods from scattering theory
we prove that this attractive potential leads to a suppression of the
quadrupole moment for CMB and B-mode angular power spectra. The scale of the
potential is determined by the Hubble parameter during slow roll. Within the
effective field theory of inflation at the grand unification (GUT) energy scale
we find that if inflation lasts a total number of efolds N_{tot} ~ 59, there is
a 10-20% suppression of the CMB quadrupole and about 2-4% suppression of the
tensor quadrupole. The suppression of higher multipoles is smaller, falling off
as 1/l^2. The suppression is much smaller for N_{tot} > 59, therefore if the
observable suppression originates in the fast roll stage, there is the upper
bound N_{tot} ~ 59.


title:
An Infrared Imaging Study of the Bipolar Proto-Planetary Nebula IRAS
  16594-4656

abstract:
  High-resolution mid-infrared images have been obtained in N-band and Q-band
for the proto-planetary nebula IRAS 16594-4656. A bright equatorial torus and a
pair of bipolar lobes can clearly be seen in the infrared images. The torus
appears thinner at the center than at the edges, suggesting that it is viewed
nearly edge-on. The infrared lobes correspond to the brightest lobes of the
reflection nebula seen in the Hubble Space Telescope (HST) optical image, but
with no sign of the point-symmetric structure seen in the visible image. The
lobe structure shows a close correspondence with a molecular hydrogen map
obtained with HST, suggesting that the dust emission in the lobes traces the
distribution of the shocked gas. The shape of the bipolar lobes shows clearly
that the fast outflow is still confined by the remnant circumstellar envelope
of the progenitor asymptotic giant branch (AGB) star. However, the
non-detection of the dust outside of the lobes suggests that the temperature of
the dust in the AGB envelope is too low for it to be detected at 20 microns.


title: Cepheid Masses: FUSE Observations of S Mus

abstract:
  S Mus is the Cepheid with the hottest known companion. The large ultraviolet
flux means that it is the only Cepheid companion for which the velocity
amplitude could be measured with the echelle mode of the HST GHRS.
Unfortunately, the high temperature is difficult to constrain at wavelengths
longer than 1200 \AA because of the degeneracy between temperature and
reddening. We have obtained a FUSE spectrum in order to improve the
determination of the temperature of the companion. Two regions which are
temperature sensitive near 16,000 K but relatively unaffected by H$_2$
absorption (940 \AA, and the Ly $\beta$ wings) have been identified. By
comparing FUSE spectra of S Mus B with spectra of standard stars, we have
determined a temperature of 17,000 $\pm$ 500 K. The resultant Cepheid mass is
6.0 $\pm$ 0.4 M$_\odot$. This mass is consistent with main sequence
evolutionary tracks with a moderate amount of convective overshoot.


title:
HST NICMOS Imaging of the Planetary-mass Companion to the Young Brown
  Dwarf 2MASS J1207334-393254

abstract:
  Multi-band (0.9 to 1.6 um) images of the TW Hydrae Association (TWA) brown
dwarf, 2MASS J1207334-393254 (also known as 2M1207), and its candidate
planetary mass companion (2M1207b) were obtained on 2004 Aug 28 and 2005 Apr 26
with HST/NICMOS. The images from these two epochs unequivocally confirm the two
objects as a common proper motion pair (16.0 sigma confidence). A new
measurement of the proper motion of 2M1207 implies a distance to the system of
59+-7 pc and a projected separation of 46+-5 AU. The NICMOS and previously
published VLT photometry of 2M1207b, extending overall from 0.9 to 3.8 um, are
fully consistent with an object of a few Jupiter masses at the canonical age of
a TWA member (~8 Myr) based on evolutionary models of young giant planets.
These observations provide information on the physical nature of 2M1207b and
unambiguously establish that the first direct image of a planetary mass
companion in orbit around a self-luminous body, other than our Sun, has been
secured.


title:
The Northern HIPASS catalogue - Data presentation, completeness and
  reliability measures

abstract:
  The Northern HIPASS catalogue (NHICAT) is the northern extension of the
HIPASS catalogue, HICAT (Meyer et al. 2004). This extension adds the sky area
between the declination range of +2 deg < dec. < +25.5 deg to HICAT's
declination range of -90 deg < dec. < +2 deg. HIPASS is a blind HI survey using
the Parkes Radio Telescope covering 71% of the sky (including this northern
extension) and a heliocentric velocity range of -1,280 km/s to 12,700 km/s .
The entire Virgo Cluster region has been observed in the Northern HIPASS. The
galaxy catalogue, NHICAT, contains 1002 sources with v_hel > 300 km/s . Sources
with -300 km/s < v_hel < 300 km/s were excluded to avoid contamination by
Galactic emission. In total, the entire HIPASS survey has found 5317 galaxies
identified purely by their HI content. The full galaxy catalogue is
publicly-available at <http://hipass.aus-vo.org>.


title: The clustering of narrow-line AGN in the local Universe

abstract:
  We have analyzed the clustering of ~ 90,000 narrow-line AGN drawn from the
Data Release 4 (DR4) of the SDSS. We compute the cross-correlation between AGN
and a reference sample of galaxies, and compare this to results for control
samples of inactive galaxies matched simultaneously in redshift,stellar
mass,concentration, velocity dispersion and the 4000A break strength. We also
compare near-neighbour counts around AGN and around the control galaxies. On
scales larger than a few Mpc, AGN have almost the same clustering amplitude as
the control sample. This demonstrates that AGN host galaxies and inactive
galaxies populate dark matter halos of similar mass.On scales between 100kpc
and 1Mpc,AGN are clustered more weakly than the control galaxies. We use mock
catalogues constructed from high-resolution N-body simulations to interpret
this anti-bias, showing that the observed effect is easily understood if AGN
are preferentially located at the centres of their dark matter halos. On scales
less than 70 kpc, AGN cluster marginally more strongly than the control sample,
but the effect is weak. When compared to the control sample, we find that only
one in a hundred AGN has an extra neighbour within a radius of 70 kpc. This
excess increases as a function of the accretion rate onto the black hole, but
it does not rise above the few percent level. Although interactions between
galaxies may be responsible for triggering nuclear activity in a minority of
nearby AGN, some other mechanism is required to explain the activity seen in
the majority of the objects in our sample. (abridged)


title: Catalog of Nearby Exoplanets

abstract:
  We present a catalog of nearby exoplanets, available at http://exoplanets.org
and ApJ 646, 505 (published version available at the link above). It contains
the 172 known low mass companions with orbits established through radial
velocity and transit measurements around stars within 200 pc. We include 5
previously unpublished exoplanets orbiting the stars HD 11964, HD 66428, HD
99109, HD 107148, and HD 164922. We update orbits for 90 additional exoplanets
including many whose orbits have not been revised since their announcement, and
include radial velocity time series from the Lick, Keck, and Anglo-Australian
Observatory planet searches. Both these new and previously published velocities
are more precise here due to improvements in our data reduction pipeline, which
we applied to archival spectra. We present a brief summary of the global
properties of the known exoplanets, including their distributions of orbital
semimajor axis, minimum mass, and orbital eccentricity.


title:
Non-Gaussian Covariance of CMB B-modes of Polarization and Parameter
  Degradation

abstract:
  The B-mode polarization lensing signal is a useful probe of the neutrino mass
and to a lesser extent the dark energy equation of state as the signal depends
on the integrated mass power spectrum between us and the last scattering
surface. This lensing B-mode signal, however, is non-Gaussian and the resulting
non-Gaussian covariance to the power spectrum cannot be ignored as correlations
between B-mode bins are at a level of 0.1. For temperature and E-mode
polarization power spectra, the non-Gasussian covariance is not significant,
where we find correlations at the 10^{-5} level even for adjacent bins. The
resulting degradation on neutrino mass and dark energy equation of state is
about a factor of 2 to 3 when compared to the case where statistics are simply
considered to be Gaussian. We also discuss parameter uncertainties achievable
in upcoming experiments and show that at a given angular resolution for
polarization observations, increasing the sensitivity beyond a certain noise
value does not lead to an improved measurement of the neutrino mass and dark
energy equation of state with B-mode power spectrum. For Planck, the resulting
constraints on the sum of the neutrino masses is ~ 0.2 eV and on the dark
energy equation of state parameter we find, sigma_w ~ 0.5.


title: Progress in Air Shower Radio Measurements: Detection of Distant Events

abstract:
  Data taken during half a year of operation of 10 LOPES antennas (LOPES-10),
triggered by EAS observed with KASCADE-Grande have been analysed. We report
about the analysis of correlations of radio signals measured by LOPES-10 with
extensive air shower events reconstructed by KASCADE-Grande, including shower
cores at large distances. The efficiency of detecting radio signals induced by
air showers up to distances of 700 m from the shower axis has been
investigated. The results are discussed with special emphasis on the effects of
the reconstruction accuracy for shower core and arrival direction on the
coherence of the measured radio signal. In addition, the correlations of the
radio pulse amplitude with the primary cosmic ray energy and with the lateral
distance from the shower core are studied.


title: Probing dark energy with future surveys

abstract:
  I review the observational prospects to constrain the equation of state
parameter of dark energy and I discuss the potential of future imaging and
redshift surveys.
  Bayesian model selection is used to address the question of the level of
accuracy on the equation of state parameter that is required before
explanations alternative to a cosmological constant become very implausible. I
discuss results in the prediction space of dark energy models. If no
significant departure from w=-1 is detected, a precision on w of order 1% will
translate into strong evidence against fluid-like dark energy, while decisive
evidence will require a precision of order 10^-3.


title:
A compact dusty disk around the Herbig Ae star HR 5999 resolved with
  VLTI / MIDI

abstract:
  We have used mid-infrared long-baseline interferometry with MIDI at the VLTI
to resolve the circumstellar material around the Herbig Ae star HR 5999,
providing the first direct measurement of its angular size, and to derive
constraints on the spatial distribution of the dust. A set of ten spectrally
dispersed (8-13 micron) interferometric measurements of HR 5999 was obtained.
The characteristic size of the emission region depends on the projected
baseline length and position angle, and it ranges between ~ 5-15
milliarcseconds (Gauss FWHM), corresponding to remarkably small physical sizes
of ~ 1-3 AU. To derive constraints on the geometrical distribution of the dust,
we compared our interferometric measurements to 2D, frequency-dependent
radiation transfer simulations of circumstellar disks and envelopes. For disk
models with radial power-law density distributions, the relatively weak but
very extended emission from outer disk regions (>~ 3 AU) leads to model
visibilities that are significantly lower than the observed visibilities,
making these models inconsistent with the MIDI data. Disk models in which the
density is truncated at outer radii of ~ 2-3 AU, on the other hand, provide
good agreement with the data. A satisfactory fit to the observed MIDI
visibilities of HR 5999 is found with a model of a geometrically thin disk that
is truncated at 2.6 AU and seen under an inclination angle of 58 degr. Neither
models of a geometrically thin disk seen nearly edge-on, nor models of
spherical dust shells can achieve agreement between the observed and predicted
visibilities. The reason why the disk is so compact remains unclear; we
speculate that it has been truncated by a close binary companion.


title:
3D-Spectroscopy of extragalactic planetary nebulae as diagnostic probes
  for galaxy evolution

abstract:
  In addition to study extragalactic stellar populations in their integrated
light, the detailed analysis of individual resolved objects has become
feasible, mainly for luminous giant stars and for extragalactic planetary
nebulae (XPNe) in nearby galaxies. A recently started project at the
Astrophysical Institute Potsdam (AIP), called ``XPN--Physics'', aims to verify
if XPNe are useful probes to measure the chemical abundances of their parent
stellar population. The project involves theoretical and observational work
packages.


title: Electric field of a point-like charge in a strong magnetic field

abstract:
  We describe the potential produced by a point electric charge placed into a
constant magnetic field, so strong that the electron Larmour length is much
shorter than its Compton length. The standard Coulomb law is modified due to
the vacuum polarization by the external magnetic field. Only mode-2 photons
mediate the static interaction. The corresponding vacuum polarization
component, taken in the one-loop approximation, grows linearly with the
magnetic field. Thanks to this fact a scaling regime occurs in the limit of
infinite magnetic field, where the potential is determined by a universal
function, independent the magnetic field. The scaling regime implies a
short-range character of interaction in the Larmour scale, expressed as a
Yukawa law. On the contrary, the electromagnetic interaction regains its
long-range character in a larger scale, characterized by the Compton length. In
this scale the tail of the Yukawa potential follows an anisotropic Coulomb law:
it decreases as the distance from the charge increases, slower along the
magnetic field and faster across. The equipotential surface is an ellipsoid
stretched along the magnetic field. As a whole, the modified Coulomb potential
is a narrower-shaped function than the standard Coulomb function, the narrower
the stronger the field. The singular behavior in the vicinity of the charge
remains unsuppressed by the magnetic field.
  These results may be useful for studying atomic spectra in super- strong
magnetic fields of several Schwinger's characteristic values.


title: Detached shells as tracers of AGB-ISM bow shocks

abstract:
  New Spitzer imaging observations have revealed the structure around the Mira
variable star R Hya to be a one-sided parabolic arc 100 arcsec to the West
stretching from North to South. We successfully model R Hya and its
surroundings in terms of an interaction of the stellar wind from an asymptotic
giant branch (AGB) star with the interstellar medium (ISM) the star moves
through. Our three-dimensional hydrodynamic simulation reproduces the structure
as a bow shock into the oncoming ISM. We propose this as another explanation of
detached shells around such stars which should be considered alongside current
theories of internal origin. The simulation predicts the existence of a tail of
ram-pressure-stripped AGB material stretching downstream. Indications for such
a tail behind R Hya are seen in IRAS maps.


title: Have we detected the most luminous ULX so far?

abstract:
  We report the XMM-Newton detection of a moderately bright X-ray source
superimposed on the outer arms of the inactive spiral galaxy MCG-03-34-63
(z=0.0213). It is clearly offset from the nucleus (by about 19'') but well
within the D25 ellipse of the galaxy, just along its bar axis. The field has
also been observed with the HST enabling us to compute a lower limit of > 94 on
the X-ray to optical flux ratio which, together with the X-ray spectrum of the
source, argues against a background AGN. On the other hand, the detection of
excess X-ray absorption and the lack of a bright optical counterpart argue
against foreground contamination. Short-timescale variability is observed,
ruling out the hypothesis of a particularly powerful supernova. If it is
associated with the apparent host galaxy, the source is the most powerful ULX
detected so far with a peak luminosity of 1.35x10^41 erg/s in the 0.5-7 keV
band. If confirmed by future multi-wavelength observations, the inferred
bolometric luminosity (about 3x10^41 erg/s) requires a rather extreme beaming
factor (larger than 115) to accommodate accretion onto a stellar-mass black
hole of 20 solar masses and the source could represent instead one of the best
intermediate-mass black hole candidate so far. If beaming is excluded, the
Eddington limit implies a mass of >2300 solar masses for the accreting compact
object.


title:
Measurement of the response of heat-and-ionization germanium detectors
  to nuclear recoils

abstract:
  The heat quenching factor Q' (the ratio of the heat signals produced by
nuclear and electron recoils of equal energy) of the heat-and-ionization
germanium bolometers used by the EDELWEISS collaboration has been measured. It
is explained how this factor affects the energy scale and the effective
quenching factor observed in calibrations with neutron sources. This effective
quenching effect is found to be equal to Q/Q', where Q is the quenching factor
of the ionization yield. To measure Q', a precise EDELWEISS measurement of Q/Q'
is combined with values of Q obtained from a review of all available
measurements of this quantity in tagged neutron beam experiments. The
systematic uncertainties associated with this method to evaluate Q' are
discussed in detail. For recoil energies between 20 and 100 keV, the resulting
heat quenching factor is Q' = 0.91+-0.03+-0.04, where the two errors are the
contributions from the Q and Q/Q' measurements, respectively. The present
compilation of Q values and evaluation of Q' represent one of the most precise
determinations of the absolute energy scale for any detector used in direct
searches for dark matter.


title:
UX Tri: Period Change Discovered and Unchanged Strong Blazhko Effect
  Confirmed

abstract:
  New CCD observations of the RRab star UX Tri after JD = 2452234 show a change
of the main pulsation period. The period is now P = 0.4669046 +/- 0.0000006
[d]. The change is delta_P = - 1.72 x 10-5 [d] if compared with the value we
previously published in IBVS 5210. A strong Blazhko effect with unchanged
Blazhko period P_B = 43.7 +/- 0.1 [d] is confirmed by this paper. Light curve
particularities around Blazhko phase phi_B = 0.0 are discussed in detail. In
one observation (JD 2453617) related to Blazhko phase phi_B = 0.12 an
exceptionally pronounced "bump" of delta_m > -0.1 magnitude was observed at
pulsation phase phi = 0.71.


title:
A new formulation of the Type Ia SN rate and its consequences on
  galactic chemical evolution

abstract:
  In recent papers Mannucci et al. (2005, 2006) suggested, on the basis of
observational arguments, that there is a bimodal distribution of delay times
for the explosion of Type Ia SNe. In this paper, we test this hypothesis in
models of chemical evolution of galaxies of different morphological type:
ellipticals, spirals and irregulars. We show that this proposed scenario is
compatible also with the main chemical properties of galaxies. When the new
rate is introduced in the two-infall model for the Milky Way, the derived Type
Ia SN rate as a function of cosmic time shows a high and broad peak at very
early epochs thus influencing the chemical evolution of the galactic halo more
than in the previous widely adopted formulations for the SNIa rate. As a
consequence of this, the [O/Fe] ratio decreases faster for [Fe/H] > -2.0 dex,
relative to the old models. For a typical elliptical of 10^11 M_sun of luminous
mass, the new rate produces average [alpha/ Fe] ratios in the dominant stellar
population still in agreement with observations. The Type Ia SN rate also in
this case shows an earlier peak and a subsequent faster decline relative to the
previous results, but the differences are smaller than in the case of our
Galaxy. We have also checked the effects of the new Type Ia SN rate on the
evolution of the Fe content in the ICM, as a consequence of its production from
cluster ellipticals and we found that less Fe in the ICM is produced with the
new rate, due to the higher fraction of Fe synthesized at early times and
remaining locked into the stars in ellipticals. For dwarf irregular galaxies
suffering few bursts of star formation we obtain [O/Fe] ratios larger by 0.2
dex relative to the previous models.