title:
Indirect imaging of an accretion disk rim in the long-period interacting
  binary W Crucis

abstract:
  Light curves of the long-period Algols are known for their complex shape
(asymmetry in the eclipse, light variations outside eclipse, changes from
cycle-to-cycle), and their interpretation is not possible in the standard model
of binary stars. Complex structures present in these active Algol systems could
be studied with the eclipse-mapping method which was successfully applied to
the new 7-color photometric observations in the Geneva system of W Cru,
belonging to the isolated group of these active Algols. Several cycles of this
long-period (198.5 days) eclipsing binary have been covered by observations. We
have used a modified Rutten's approach to the eclipse-mapping. The optimization
of the system's parameters and the recovery of the disk intensity distribution
are performed using a genetic algorithm (GA). It is found that a hot component
is hidden in the thick accretion disk which confirms previous findings. The
mass of the component, M1 = 8.2 Ms indicates that it is a mid-B type star. The
mass-losing component is filling its critical lobe which means it is a G-type
supergiant with a mass M2 = 1.6 Ms. The disk is geometrically very extended and
its outer radius is about 80% of the primary's critical lobe. A reconstructed
image reveals a rather clumpy and nonuniform brightness distribution of an
accretion disk rim in this almost edge-on seen system. This clumpyness accounts
for light curve distortions and asymmetries, as well as for secular changes.


title:
3D spectroscopy with VLT/GIRAFFE - II: Are Luminous Compact Galaxies
  merger remnants ?

abstract:
  Luminous Compact Galaxies are enigmatic sources by many aspects. They can
reach the luminosity of the Milky Way within a radius of only a few kpc. They
also represent one of the most rapidly evolving populations of galaxies since
they represent up to 1/5 of the luminous galaxies at redshift z= 0.7 while
being almost absent in the local Universe. The measurement of their dynamics is
crucial to our understanding of LCGs since this has the potential of telling us
which physical process(es) that drives them, and ultimately to link them to the
existing present-day galaxies. Here we derive the 3 dimensional velocity fields
and velocity dispersion (sigma) maps of 17 Luminous Compact Galaxies selected
from the Canada France Redshift Survey and the Hubble Deep Field South with
redshifts ranging from z=0.4 to z=0.75. We find that only 18% of them show
rotational velocity fields typical of rotating disks, the others showing more
complex kinematics. Assuming that LCGs are not too far from equilibrium, about
half of LCGs then appear to be either non-relaxed objects, or objects that are
not supported by velocity dispersion alone. This supports the view that an
important fraction of LCGs are probably mergers. It brings additional support
to the ``spiral rebuilding scenario'' in which LCGs correspond to a previous or
post-merger phase before the disk re-building.


title:
3D spectroscopy with VLT/GIRAFFE: I- the true Tully Fisher relationship
  at z~0.6

abstract:
  A precise derivation of the evolution of the Tully Fisher is crucial to
understand the interplay between dark matter and baryonic matter in
cosmological models, Using 15 deployable integral field units of FLAMES/GIRAFFE
at VLT, we have recovered the velocity fields of 35 galaxies at intermediate
redshift (0.4 < z < 0.75). This facility is able to recover the velocity fields
of almost all the emission line galaxies with Iab <=22.5 and W_0(OII)>=15A In
our sample, we find only 35% rotating disks. These rotating disks produce a
Tully-Fisher relationship (stellar mass or M_K versus V_max) which has
apparently not evolved in slope, zero point and scatter since z=0.6. The only
evolution found is a brightening of the B band luminosity of a third of the
disks, possibly due to an enhancement of the star formation. The very large
scatters found in previously reported Tully-Fisher relationships at moderate
redshifts are caused by the numerous (65%) galaxies with perturbed or complex
kinematics. Those galaxies include minor or major mergers, merger remnants
and/or inflow/outflows and their kinematics can be easily misidentified by slit
spectroscopy. Their presence suggests a strong evolution in the dynamical
properties of galaxies during the last 7 Gyrs.


title:
3D spectroscopy with VLT/GIRAFFE - III: Mapping electron densities in
  distant galaxies

abstract:
  We used the moderately high spectral resolution of FLAMES/GIRAFFE (R=10000)
to derive electron densities from [OII] line ratios in 6 galaxies at z~0.55.
These measurements have been done through the GIRAFFE multiple integral field
units and are the very first mapping of electron densities in such distant
objects. This allows us to confirm an outflow and identify the role of giant
HII regions in galactic disks. Such measurements could be used in the future to
investigate the nature of the physical processes responsible for the high star
formations rates observed in galaxies between z~0.4 and z~1.


title: Wakes of ram pressure stripped disc galaxies

abstract:
  Spiral galaxies that move through the intracluster medium lose a substantial
amount of their gas discs due to ram pressure stripping. The recent
observations of NGC 4388 by Oosterloo & van Gorkom 2005 reveal a tail of
stripped gas of ~ 100 kpc behind the source galaxy. We present first 3D
hydrodynamical simulations of the evolution of such ram pressure stripped
tails.
  We find that if the ICM wind does not vary significantly over a period of a
few 100 Myr, subsonic galaxies produce a tail with regular features similar to
a von-Karman vortex street. In this case, the tail widens systematically by
about 45 kpc per 100 kpc distance behind the source galaxy. The widening rate
is independent of the galaxy's inclination for a large range of inclinations.
For supersonic galaxies, the tail is more irregular than for subsonic ones.
  The tail observed for NGC 4388 is narrower than the tails in our simulations.
Reasons for this difference may be additional physical processes such as heat
conduction or viscosity. In addition, we conclude that the observed S-shape of
this tail is not due to von Karman oscillations, because this galaxy is likely
to move supersonically. A reason for the observed shape may be motions in the
ambient ICM.
  Finally, we discuss implications for the distribution of metals in the ICM
due to ram pressure stipping.


title:
Consistency between deep crustal heating of strange stars in
  superbursters and soft X-ray transients

abstract:
  Both superbursters and soft X-ray transients probe the process of deep
crustal heating in compact stars. It was recently shown that the transfer of
matter from crust to core in a strange star can heat the crust and ignite
superbursts provided certain constraints on the strange quark matter equation
of state are fulfilled. We derive corresponding constraints on the equation of
state for soft X-ray transients assuming their quiescent emission is powered in
the same way, and further discuss the time dependence of this heating mechanism
in transient systems. We approach this using a simple parametrized model for
deep crustal heating in strange stars assuming slow neutrino cooling in the
core and blackbody photon emission from the surface.The constraints derived for
hot frequently accreting soft X-ray transients are always consistent with those
for superbursters. The colder sources are consistent for low values of the
quark matter binding energy, heat conductivity and neutrino emissivity. The
heating mechanism is very time dependent which may help to explain cold sources
with long recurrence times. Thus deep crustal heating in strange stars can
provide a consistent explanation for superbursters and soft X-ray transients.


title: A neutron-star-driven X-ray flash associated with supernova SN 2006aj

abstract:
  Supernovae connected with long-duration gamma-ray bursts (GRBs) are
hyper-energetic explosion resulting from the collapse of very massive stars
(about 40Mo, where Mo is the mass of the Sun) stripped of their outher hydrogen
and helium envelopes. A very massive progenitor, collapsing to a black hole,
was thought to be a requirement for the launch of a GRB. Here we report the
results of modelling the spectra and light curve of SN 2006aj, which
demonstrate that the supernova had a much smaller explosion energy and ejected
much less mass than the other GRB-sueprnovae, suggesting that it was produced
by a star whose initial mass was only about 20Mo. A star of this mass is
expected to form a neutron star rather than a black hole when its core
collapses. The smaller explosion energy of SN 2006aj is matched by the weakness
and softness of GRB 060218 (an X-ray flash), and the weakness of the radio flux
of the supernova. Our results indicate that the supernova-GRB connection
extends to a much broader range of stellar masses than previously thought,
possibly involving different physical mechanisms: a `collapsar' for the more
massive stars collapsing to a black hole, and magnetic activity of the nascent
neutron star for the less massive stars.


title:
The Distribution of Ortho-H_2D+(1_1,0 - 1_1,1) in L1544: Tracing the
  Deuteration Factory in Prestellar Cores

abstract:
  Prestellar cores are unique laboratories for studies of the chemical and
physical conditions preceding star formation. We observed the prestellar core
L1544 in the fundamental transition of ortho-H2D+ (1_1,0-1_1,1) at different
positions over 100", and found a strong correlation between its abundance and
the CO depletion factor. We also present a tentative detection of the
fundamental transition of para-D2H+ (1_1,0-1_0,1) at the dust emission peak.
Maps in N2H+, N2D+, HCO+ and DCO+ are used, and interpreted with the aid of a
spherically symmetric chemical model that predicts the column densities and
abundances of these species as a function of radius. The correlation between
the observed deuterium fractionation of H3+, N2H+ and HCO+ and the observed
integrated CO depletion factor across the core can be reproduced by this
chemical model. In addition a simpler model is used to study the H2D+
ortho-to-para ratio. We conclude that, in order to reproduce the observed
ortho-H2D+ observations, the grain radius should be larger than 0.3 microns.


title: On the nature of radio pulsars with long periods

abstract:
  It is shown that the drift waves near the light cylinder can cause the
modulation of the emission with periods of the order several seconds. These
periods explain the intervals between successive pulses observed in "magnetars"
and radio pulsars with long periods. The model under consideration makes it
possible to calculate the real rotation periods of the host neutron stars. They
are less than 1 sec for the investigated objects. The magnetic fields at the
surface of the neutron star of the order 10^(11)-10^(13) G and equal to the
usual fields for known radio pulsars


title: Status report of the ANTARES experiment

abstract:
  The ANTARES Collaboration is building an underwater neutrino telescope in the
Mediterranean sea. The telescope is designed to search for high energy (E $>1$
TeV) galactic and extra-galactic neutrino sources, but could also be sensitive
to neutrinos originating from the decay of neutralino and exotic particles. The
detector is a 3-dimensional array of photomultipliers located at a depth of
2500 m, 40 km from the La Seyne sur Mer shore (near Toulon, France). During the
year 2005 a full scale test line and an instrumented line have been
successfully operated. In the winter '05-'06 the first full 480 m line will be
deployed and connected to the shore station.


title:
The production of short-lived radionuclides by new non-rotating and
  rotating Wolf-Rayet model stars

abstract:
  It has been speculated that WR winds may have contaminated the forming solar
system, in particular with short-lived radionuclides (half-lives in the
approximate 10^5 - 10^8 y range) that are responsible for a class of isotopic
anomalies found in some meteoritic materials. We revisit the capability of the
WR winds to eject these radionuclides using new models of single non-exploding
WR stars with metallicity Z = 0.02. The earlier predictions for non-rotating WR
stars are updated, and models for rotating such stars are used for the first
time in this context. We find that (1) rotation has no significant influence on
the short-lived radionuclide production by neutron capture during the core
He-burning phase, and (2) 26Al, 36Cl, 41Ca, and 107Pd can be wind-ejected by a
variety of WR stars at relative levels that are compatible with the meteoritic
analyses for a period of free decay of around 10^5 y between production and
incorporation into the forming solar system solid bodies. We confirm the
previously published conclusions that the winds of WR stars have a radionuclide
composition that can meet the necessary condition for them to be a possible
contaminating agent of the forming solar system. Still, it remains to be
demonstrated from detailed models that this is a sufficient condition for these
winds to have provided a level of pollution that is compatible with the
observations.


title: Cut-out sets, fractal voids and cosmic structure

abstract:
  "Cut-out sets" are fractals that can be obtained by removing a sequence of
disjoint regions from an initial region of d-dimensional euclidean space.
Conversely, a description of some fractals in terms of their void complementary
set is possible. The essential property of a sequence of fractal voids is that
their sizes decrease as a power law, that is, they follow Zipf's law. We prove
the relation between the box dimension of the fractal set (in d <= 3) and the
exponent of the Zipf law for convex voids; namely, if the Zipf law exponent e
is such that 1 < e < d/(d-1) and, in addition, we forbid the appearance of
degenerate void shapes, we prove that the corresponding cut-out set has box
dimension d/e (d-1 < d/e < d). We explore the application of this result to the
large scale distribution of matter in cosmology, in connection with ``cosmic
foam'' models.

categories: astro-ph cond-mat.stat-mech math-ph math.MP


title:
On the Unusual Depletions toward Sk 155, or What Are the Small
  Magellanic Cloud Dust Grains Made of?

abstract:
  The dust in the Small Magellanic Cloud (SMC), an ideal analog of primordial
galaxies at high redshifts, differs markedly from that in the Milky Way by
exhibiting a steeply rising far-ultraviolet extinction curve, an absence of the
2175 Angstrom extinction feature, and a local minimum at ~12 micron in its
infrared emission spectrum, suggesting the lack of ultrasmall carbonaceous
grains (i.e. polycyclic aromatic hydrocarbon molecules) which are ubiquitously
seen in the Milky Way. While current models for the SMC dust all rely heavily
on silicates, recent observations of the SMC sightline toward Sk 155 indicated
that Si and Mg are essentially undepleted and the depletions of Fe range from
mild to severe, suggesting that metallic grains and/or iron oxides, instead of
silicates, may dominate the SMC dust. However, in this Letter we apply the
Kramers-Kronig relation to demonstrate that neither metallic grains nor iron
oxides are capable of accounting for the observed extinction; silicates remain
as an important contributor to the extinction, consistent with current models
for the SMC dust.


title: Luminous Infrared Galaxies in the Local Universe

abstract:
  We study the morphology and star formation properties of 159 local luminous
infrared galaxy (LIRG) using multi-color images from Data Release 2 (DR2) of
the Sloan Digital Sky Survey (SDSS). The LIRGs are selected from a
cross-correlation analysis between the IRAS survey and SDSS. They are all
brighter than 15.9 mag in the r-band and below redshift ~ 0.1, and so can be
reliably classified morphologically. We find that the fractions of
interacting/merging and spiral galaxies are ~ 48% and ~ 40% respectively. Our
results complement and confirm the decline (increase) in the fraction of spiral
(interacting/merging) galaxies from z ~1 to z ~ 0.1, as found by Melbourne, Koo
& Le Floc'h (2005). About 75% of spiral galaxies in the local LIRGs are barred,
indicating that bars may play an important role in triggering star formation
rates > 20 M_{sun}/yr in the local universe. Compared with high redshift LIRGs,
local LIRGs have lower specific star formation rates, smaller cold gas
fractions and a narrower range of stellar masses. Local LIRGs appear to be
either merging galaxies forming intermediate mass ellipticals or spiral
galaxies undergoing high star formation activities regulated by bars.


title: Perturbations in stochastic inflation

abstract:
  The perturbative approach to stochastic inflation is used to determine the
spectrum of density fluctuations and gravitational waves due to the coarse
grained field. The amplitude of the curvature fluctuation spectrum, the
spectral index and the running of the spectral index are in general found to be
smaller than in the standard approach to inflation. Furthermore, the amount of
non-gaussianity due to the second order perturbation is estimated.


title:
Recent star formation in the inner Galactic Bulge seen by ISOGAL. I -
  Classification of bright mid-IR sources in a test field

abstract:
  Context: The stellar populations in the central region of the Galaxy are
poorly known because of the high visual extinction and very great source
density in this direction.
  Aims: To use recent infrared surveys for studying the dusty stellar objects
in this region.
  Methods: We analyse the content of a 20x20 arcmin^2 field centred at
(l,b)=(-0.27,-0.06) observed at 7 and 15 microns as part of the ISOGAL survey.
These ISO observations are more than an order of magnitude better in
sensitivity and spatial resolution than the IRAS observations. The sources are
cross-associated with other catalogues to identify various types of objects. We
then derive criteria to distinguish young objects from post-main sequence
stars.
  Results: We find that a sample of about 50 young stellar objects and
ultra-compact HII regions emerges, out of a population of evolved AGB stars. We
demonstrate that the sources colours and spatial extents, as they appear in the
ISOGAL catalogue, possibly complemented with MSX photometry at 21 microns, can
be used to determine whether the ISOGAL sources brighter than 300 mJy at 15
microns (or [15] < 4.5 mag) are young objects or late-type evolved stars.


title:
Detailed Chemical Evolution of Carina and Sagittarius Dwarf Spheroidal
  Galaxies

abstract:
  In order to verify the effects of the most recent data on the evolution of
Carina and Sagittarius Dwarf Spheroidal Galaxies (dSph) and to set tight
constraints on the main parameters of chemical evolution models, we study in
detail the chemical evolution of these galaxies through comparisons between the
new data and the predictions of a model, already tested to reproduce the main
observational constraints in dSphs. Several abundance ratios, such as
[$\alpha$/Fe], [Ba/Fe] and [Eu/Fe], and the metallicity distribution of stars
are compared to the predictions of our models adopting the observationally
derived star formation histories in these galaxies. These new comparisons
confirm our previously suggested scenario for the evolution of these galaxies,
and allow us to better fix the star formation and wind parameters. In
particular, for Carina the comparisons indicate that the best efficiency of
star formation is $\nu = 0.15 Gyr^{-1}$, that the best wind efficiency
parameter is $w_i$ = 5 (the wind rate is five times stronger than the star
formation rate), and that the star formation history, which produces the best
fit to the observed metallicity distribution of stars is characterized by
several episodes of activity. In the case of Sagittarius our results suggest
that $\nu=3 Gyr^{-1}$ and $w_i=9$, again in agreement with our previous work.
Finally, we show new predictions for [N/Fe] and [C/Fe] ratios for the two
galaxies suggesting a scenario for Sagittarius very similar to the one of the
solar vicinity in the Milky Way, except for a slight decrease of [N/Fe] ratio
at high metallicities due to the galactic wind. For Carina we predict a larger
[N/Fe] ratio at low metallicities, reflecting the lower star formation
efficiency of this galaxy relative to Sagittarius and the Milky Way.


title: Clumpy shocks and the clump mass function

abstract:
  In this paper, we examine whether clumpy, colliding, flows could be
responsible for the clump mass functions that have been observed in several
regions of embedded star formation, which have been shown to be described by a
Salpeter type slope. The flows presented here, which comprise a population of
initially identical clumps and the calculations are performed with and without
the inclusion of self-gravity. When the shock region is at its densest, we find
that the clump mass spectrum is always well modelled by a Salpeter type slope.
This is true regardless of whether the self-gravity is included in the
simulations or not. In the non-self-gravitating simulations, this slope is
retained at lower Mach numbers (Mach 5 and 10) as the simulations progress past
the densest phase. In the simulations which include self-gravity, we find that
low Mach number runs yield a flatter mass function after the densest phase.
This is simply a result of increased coagulation due to gravitational collapse
of the flows. In the high Mach number runs (Mach 20) the Salpeter slope is
always lost. The self gravitating calculations also show that the sub-group of
gravitationally bound clumps in which star formation occurs, always contain the
most massive clumps in the population. The mass function of these bound star
forming clumps is not at all similar to the Salpeter type mass function
observed for stars in the field. We conclude that the clump mass function may
not only have nothing to do with gravity, but also nothing to do with the star
formation process and the resulting mass distribution of stars. This raises
doubt over the claims that the clump mass function is the origin of the stellar
IMF, for regions such as rho Oph, Serpens and the Orion B cloud.


title:
A historic jet-emission minimum reveals hidden spectral features in 3C
  273

abstract:
  Aims. The aim of this work is to identify and study spectral features in the
quasar 3C 273 usually blended by its strong jet emission. Method. A historic
minimum in the sub-millimetre emission of 3C 273 triggered coordinated
multi-wavelength observations in June 2004. X-ray observations from the
INTEGRAL, XMM-Newton and RXTE satellites are complemented by ground-based
optical, infrared, millimetre and radio observations. The overall spectrum is
used to model the infrared and X-ray spectral components. Results. Three
thermal dust emission components are identified in the infrared. The dust
emission on scales from 1 pc to several kpc is comparable to that of other
quasars, as expected by AGN unification schemes. The observed weakness of the
X-ray emission supports the hypothesis of a synchrotron self-Compton origin for
the jet component. There is a clear soft-excess and we find evidence for a very
broad iron line which could be emitted in a disk around a Kerr black hole.
Other signatures of a Seyfert-like X-ray component are not detected.


title: Gas metallicity diagnostics in star-forming galaxies

abstract:
  Generally the gas metallicity in distant galaxies can only be inferred by
using a few prominent emission lines. Various theoretical models have been used
to predict the relationship between emission line fluxes and metallicity,
suggesting that some line ratios can be used as diagnostics of the gas
metallicity in galaxies. However, accurate empirical calibrations of these
emission line flux ratios from real galaxy spectra spanning a wide metallicity
range are still lacking. In this paper we provide such empirical calibrations
by using the combination of two sets of spectroscopic data: one consisting of
low-metallicity galaxies with a measurement of [OIII]4363, and the other one
consisting of galaxies in the SDSS DR4 whose metallicity has been determined
from various strong emission lines in their spectra. This combined data set
constitutes the largest sample of galaxies with information on the gas
metallicity available so far and spanning the widest metallicity range. Our
empirical diagrams show that the line ratio [OIII]/[OII] is a useful tool to
break the degeneracy in the R_23 parameter when no information on the [NII]
line is available. The line ratio [NeIII]/[OII] also results to be a useful
metallicity indicator for high-z galaxies. Finally, we compare these empirical
relations with photoionization models. We find that the empirical
R_23-metallicity sequence is strongly discrepant with respect to the trend
expected by models with constant ionization parameter, which is interpreted as
a consequence of a strong metallicity dependence of the average ionization
parameter in galaxies. This result should warn about the use of theoretical
models with constant ionization parameter to infer metallicities from observed
line ratios. (abbreviated)


title:
Incorporating the molecular gas phase in galaxy-size numerical
  simulations: first applications in dwarf galaxies

abstract:
  We present models of the evolution of the gaseous and stellar content of
galaxies incorporating the formation of H_2 out of HI gas as part of such a
model. We do so by formulating a subgrid model for gas clouds that uses
well-known cloud scaling relations and solves for the HI-H_2 balance set by the
H_2 formation on dust grains and its FUV-induced photodissociation by the
temporally and spatially varying interstellar radiation field. This allows the
seamless tracking of the evolution of the H_2 gas phase, its precursor Cold
Neutral Medium (CNM) HI gas, simultaneously with the star formation. Our most
important findings are: a) a significant dependence of the HI-H_2 transition
and the resultant H_2 gas mass on the ambient metallicity and the H_2 formation
rate, b) the important influence of the characteristic star formation timescale
(regulating the ambient FUV radiation field) on the equilibrium H_2 gas mass
and c) the possibility of a diffuse H_2 gas phase. Finally, we implement and
briefly explore a novel approach of using the ambient H_2 gas mass fraction as
a criterion for the onset of star formation. (abridged)


title: Carbon Stars in the Hamburg/ESO Survey: Abundances

abstract:
  We have carried out a detailed abundance analysis for a sample of 16 carbon
stars found among candidate extremely metal-poor (EMP) stars from the
Hamburg/ESO Survey. We find that the Fe-metallicities for the cooler C-stars
(Teff ~ 5100K) have been underestimated by a factor of ~10 by the standard HES
survey tools. The results presented here provided crucial supporting data used
by Cohen et al (2006) to derive the frequency of C-stars among EMP stars.
  C-enhancement in these EMP C-stars appears to be independent of
Fe-metallicity and approximately constant at ~1/5 the solar C/H. The mostly low
C12/C13 ratios (~4) and the high N abundances in many of these stars suggest
that material which has been through proton burning via the CN cycle comprises
most of the stellar envelope. C-enhancement is associated with strong
enrichment of heavy nuclei beyond the Fe-peak for 12 of the 16 stars. The
remaining C-stars from the HES, which tend to be the most Fe-metal poor, show
no evidence for enhancement of the heavy elements. Very high enhancements of
lead are detected in some of the C-stars with highly enhanced Ba. (We show
that) the s-process is responsible for the enhancement of the heavy elements
for the majority of the C-stars in our sample.
  We suggest that both the s-process rich and Ba-normal C-stars result from
phenomena associated with mass transfer in binary systems. This leads directly
to the progression from C-stars to CH stars and then to Ba stars as the
Fe-metallicity increases. (abridged and slightly edited to shorten)


title:
Starbursts near supermassive black holes: young stars in the Galactic
  Center, and gravitational waves in LISA band

abstract:
  We propose a scenario in which massive stars form in a self-gravitating
gaseous disc around a supermassive black hole. We find that once the surface
density of the disc exceeds a critical value, the disc fragments into dense
clumps. The clumps accrete material from the remaining disc and merge into
larger clumps; the upper mass of a merged clump is a few tens to a few hundreds
of solar mass. This picture fits well with the observed young stellar discs
near the SgrA* black hole in the Galactic Center. In particular, we show how
the masses and spatial distribution of the young stars, and the total mass in
the Galactic Center discs can be explained. However, explaining the origin of
the several young stars closest to the black hole (the S-stars) is more
problematic: their orbits are compact, eccentric, and have random orientation.
We propose that the S-stars were born in a previous starburst(s), and then
migrated through their parent disc via type I or runaway migration. Their
orbits were then randomized by the Rauch-Tremaine resonant relaxation. We then
explore the consequences of the star-formation scenario for AGN discs, which
are continuously resupplied with gas. We argue that some compact remnants
generated by the starburst will get embedded in the disc. The disc-born
stellar-mass black holes will interact gravitationally with the massive
accretion disc and be dragged towards the central black hole. Merger of a
disc-born black hole with the central black hole will produce a burst of
gravitational waves. If the central black hole is accreting at a rate
comparable to the Eddington limit, the gas drag from the accretion disc will
not alter significantly the dynamics of the final year of merger, and the
gravitational waves should be observable by LISA.


title: Dark Energy in the Dark Ages

abstract:
  Non-negligible dark energy density at high redshifts would indicate dark
energy physics distinct from a cosmological constant or ``reasonable''
canonical scalar fields. Such dark energy can be constrained tightly through
investigation of the growth of structure, with limits of \la2% of total energy
density at z\gg1 for many models. Intermediate dark energy can have effects
distinct from its energy density; the dark ages acceleration can be constrained
to last less than 5% of a Hubble e-fold time, exacerbating the coincidence
problem. Both the total linear growth, or equivalently \sigma_8, and the shape
and evolution of the nonlinear mass power spectrum for z<2 (using the
Linder-White nonlinear mapping prescription) provide important windows. Probes
of growth, such as weak gravitational lensing, can interact with supernovae and
CMB distance measurements to scan dark energy behavior over the entire range
z=0-1100.


title: Alice: The Rosetta Ultraviolet Imaging Spectrograph

abstract:
  We describe the design, performance and scientific objectives of the
NASA-funded ALICE instrument aboard the ESA Rosetta asteroid flyby/comet
rendezvous mission. ALICE is a lightweight, low-power, and low-cost imaging
spectrograph optimized for cometary far-ultraviolet (FUV) spectroscopy. It will
be the first UV spectrograph to study a comet at close range. It is designed to
obtain spatially-resolved spectra of Rosetta mission targets in the 700-2050 A
spectral band with a spectral resolution between 8 A and 12 A for extended
sources that fill its ~0.05 deg x 6.0 deg field-of-view. ALICE employs an
off-axis telescope feeding a 0.15-m normal incidence Rowland circle
spectrograph with a concave holographic reflection grating. The imaging
microchannel plate detector utilizes dual solar-blind opaque photocathodes (KBr
and CsI) and employs a 2 D delay-line readout array. The instrument is
controlled by an internal microprocessor. During the prime Rosetta mission,
ALICE will characterize comet 67P/Churyumov-Gerasimenko's coma, its nucleus,
and the nucleus/coma coupling; during cruise to the comet, ALICE will make
observations of the mission's two asteroid flyby targets and of Mars, its
moons, and of Earth's moon. ALICE has already successfully completed the
in-flight commissioning phase and is operating normally in flight. It has been
characterized in flight with stellar flux calibrations, observations of the
Moon during the first Earth fly-by, and observations of comet Linear T7 in 2004
and comet 9P/Tempel 1 during the 2005 Deep Impact comet-collision observing
campaign


title: Radio continuum monitoring of the extreme carbon star IRC+10216

abstract:
  We describe Very Large Array observations of the extreme carbon star
IRC+10216 at 8.4, 14.9, and 22.5 GHz made over a two year period. We find
possible variability correlated with the infrared phase and a cm- to
sub-millimeter wavelength spectral index very close to 2. The variability,
observed flux densities, and upper limit on the size are consistent with the
emission arising from the stellar photosphere or a slightly larger radio
photosphere.


title:
Recovering the Inflationary Potential and Primordial Power Spectrum With
  a Slow Roll Prior: Methodology and Application to WMAP 3 Year Data

abstract:
  We introduce a new method for applying an inflationary prior to a
cosmological dataset that includes relations between observables at arbitrary
order in the slow roll expansion. The process is based on the inflationary flow
equations, and the slow roll parameters appear explicitly in the cosmological
parameter set. We contrast our method to other ways of imposing an inflationary
prior on a cosmological dataset, and argue that this method is ideal for use
with heterogeneous datasets. In particular, it would be well suited to
exploiting any direct detection of fundamental tensor modes by a BBO-style
mission. To demonstrate the practical use of this method we apply it to the
WMAPI+All dataset, and the newly released WMAPII dataset on its own and
together with the SDSS data. We find that all basic classes of single field
inflationary models are still allowed at the 1-2sigma level, but the overall
parameter space is sharply constrained. In particular, we find evidence that
the combination of WMAPII+SDSS is sensitive to effects arising from terms that
are quadratic in the two leading-order slow roll parameters.


title: Cosmological Constraints from the Red-Sequence Cluster Survey

abstract:
  [abridged] We present a first cosmological analysis of a refined cluster
catalog from the Red-Sequence Cluster Survey (RCS). The input cluster sample is
derived from 72.07 square degrees of imaging data [...] The catalog contains
956 clusters over 0.35<z<0.95, limited by cluster richness and richness error.
The calibration of the survey images has been extensively cross-checked against
publicly available Sloan Digital Sky Survey imaging [...] We analyze the
cluster sample via a general self-calibration technique including scatter in
the mass-richness relation [...]. We fit simultaneously for Omega_M and
sigma_8, and four parameters describing the calibration of cluster richness to
mass, its evolution with redshift, and scatter in the richness-mass relation.
The principal goal of this general analysis is to establish the consistency (or
lack thereof) between the fitted parameters (both cosmological and cluster mass
observables) and available results on both from independent measures. From an
unconstrained analysis, Omega_M and sigma_8 are 0.31+0.11-0.10 and
0.67+0.18-0.13 respectively. An analysis including Gaussian priors on the slope
and zeropoint of the mass-richness relation gives very similar results:
0.30+0.12-0.11 and 0.70+0.27-0.15. Both analyses are in good agreement with the
current literature. The parameters describing the mass-richness relation in the
unconstrained fit are also eminently reasonable and agree with existing
follow-up data on both the RCS-1 and other cluster samples. Our results
directly demonstrate that future surveys (optical and otherwise), with much
larger samples of clusters, can give constraints competitive with other probes
of cosmology.


title:
Limits on Defects Formation and Hybrid Inflationary Models with
  Three-Year WMAP Observations

abstract:
  We confront the predicted effects of hybrid inflationary models on the Cosmic
Microwave Background (CMB) with three years of Wilkinson Microwave Anisotropy
Probe (WMAP) observations. Using model selection, we compare the ability of a
simple flat power-law LCDM model to describe the data to that of hybrid
inflationary models involving global or local cosmic strings, or global
textures. We find that it is statistically impossible to distinguish between
these models: they all give a similar description of the data, the maximum
ratio of the various Bayesian evidences involved being never higher than e^{0.1
\pm 0.5}. We then derive the maximum contribution that topological defects can
make to the CMB, and place an upper bound on the possible value of cosmic
strings' tension of G\mu \leq 2.1 \times 10^{-7} (68% confidence limit).
Finally, we give the corresponding constraints on the D-term strings' mass
scale, as well as limits on the F- and D-term coupling constants (\kappa and
\lambda) and inflationary scales (M and \sqrt{\xi}).


title:
Swift Observations of the highly X-ray variable Narrow Line Seyfert 1
  galaxy RX J0148.3-2758

abstract:
  We report on Swift observations of the Narrow-Line Seyfert 1 galaxy (NLS1) RX
J0148.3--2758. It was observed for 41.6 ks in 2005 May and for 15.8 ks in 2005
December. On short as well as on long timescales RX J0148.3--2758 is a highly
variable source. It doubles its X-ray flux within 18-25 ks. The observation of
2005 December 09, which had a flux 4 times lower than during the 2005 May
observations, shows a significant hardening of the X-ray hardness ratio
compared with the 2005-May and 2005-December 20/21 observations. A detailed
analysis of the X-ray spectra shows that we actually observe two spectral
changes in RX J0148.3-2758: First a decrease of the soft X-ray component
between 2005 May and December 09, which is most likely due to an increase of
the intrinsic absorber column, and second a decrease of the hard X-ray flux in
the December 20/21 observations. The soft X-ray spectral slope $\alpha_{\rm X,
soft}$=2.58$^{+0.15}_{-0.12}$ during the high state in 2005 May agrees well
with that measured by ROSAT (\axs=2.54\plm0.82). In contrast to the strong
X-ray variability, the analysis of the Swift UVOT photometry from December 2005
of RX J0148.3--2758 shows no significant variability in any of the 6 UVOT
filters. From the simultaneous X-ray and UV observations in 2005 December we
measured the X-ray loudness alpha-ox varies between alpha-ox=1.5 and 1.8. Our
Swift observations of RX J0148.3-2758 demonstrate the great potential the
multi-wavelength observatory Swift has for AGN science. (shortened)


title: A jet-cloud interaction in the 3C 196 environment

abstract:
  Powerful radio galaxies and radio-loud quasars at high redshifts are
frequently associated with extended emission-line regions (EELRs). Here we
investigate the [O II] EELR around the quasar 3C 196 at z=0.871 using integral
field spectroscopy. We also detect extended [Ne II] emission at a distance of
about 30 kpc from the core. The emission is aligned with the radio hot spots
and shows a redshifted and a blueshifted component with a velocity difference
of ~800 km s^-1. The alignment effect and large velocities support the
hypothesis that the EELR is caused by a jet-cloud interaction, which is
furthermore indicated by the presence of a pronounced bend in the radio
emission at the location of the radio hot spots. We also report observations of
two other systems which do not show as clear indications of interactions. We
find a weaker alignment of an [O II] EELR from the z=0.927 quasar 3C 336, while
no EELR is found around the core-dominated quasar OI 363 at z=0.63.


title:
Disk Winds, Jets, and Outflows: Theoretical and Computational
  Foundations

abstract:
  We review advances in the theoretical and computational studies of disk
winds, jets and outflows including: the connection between accretion and jets,
the launch of jets from magnetized disks, the coupled evolution of jets and
disks, the interaction of magnetized young stellar objects with their
surrounding disks and the relevance to outflows, and finally, the link between
jet formation and gravitational collapse. We also address the predictions that
the theory makes about jet kinematics, collimation, and rotation, that have
recently been confirmed by high spatial and spectral resolution observations.
Disk winds have a universal character that may account for jets and outflows
during the formation of massive stars as well as brown dwarfs.


title: PIC Simulations of Prompt GRB Emissions

abstract:
  We review PIC simulation results of GRB emissions for both the Poynting flux
and shock scenarios


title:
CMB statistical anisotropy, multipole vectors and the influence of the
  dipole

abstract:
  A simple algorithm which gives the multipole vectors in terms of the roots of
a polynomial is given. We find that the reported alignmet of the low l
multipole vectors can be summarised as an anti-alignmet of these with the
dipole direction. This anti-alignment is not only present in l=2 and 3 but also
for l=5 and higher. This alignment is likely due to non-linearity in the data
processing. Our results are based on the three year WMAP data, we also list
corresponding results for the first year data.


title: Sustained Acceleration of Over-dense Plasmas by Colliding Laser Pulses

abstract:
  We review recent PIC simulation results which show that double-sided
irradiaton of a thin overdense plasma slab by ultra-intense laser pulses from
both sides can lead to sustained comoving acceleration of surface electrons to
energies much higher than the conventional ponderomotive limit. The
acceleration stops only when the electrons drift transversely out of the laser
beam. We show results of parameter studies based on this concept and discuss
future laser experiments that can be used to test these computer results.


title:
The Effective Temperatures and Physical Properties of Magellanic Cloud
  Red Supergiants: The Effects of Metallicity

abstract:
  We use the MARCS stellar atmosphere to derive the physical properties of 36
red supergiants (RSGs) in the LMC, and 39 RSGs in the SMC using
moderate-resolution optical spectrophotometry (4000-9000A) and broad-band
colors (V-R, V-K). The results from the dereddened V-R colors are in good
agreement with those derived from the spectrophotometry, but the dereddened V-K
colors give temperatures that are 3-4% warmer for the SMC data, with the LMC
and Milky Way showing a smaller but similar effect. We conclude that this
discrepancy is due to the limitations of 1D models. Our newly derived effective
temperatures and bolometric luminosities bring the Magellanic Cloud RSGs into
good agreement with stellar evolutionary models that include the effects of
rotation. A typical M2~I in the SMC is about 150 K cooler than its Galactic
counterpart; one in the LMC is about 50 K cooler. This is in the sense expected
due to the lower chemical abundances in the SMC and LMC, although it is not
sufficient to explain the shift in average RSG spectral type seen between the
SMC, LMC, and Milky Way. Instead, that is due primarily to the change in
Hayashi limit with metallicity, as first proposed by Elias et al. (1985).
Finally, our study confirms that many RSGs in the Magellanic Clouds are
significantly more reddened than OB stars, consistent with our recent findings
for Galactic stars that circumstellar dust may contribute several magnitudes of
extra visual extinction.


title: Circular Polarization in Pulsar Integrated Profiles: Updates

abstract:
  We update the systematic studies of circular polarization in integrated pulse
profiles by Han et al (1998). Data of circular polarization profiles are
compiled. Sense reversals can occur in core or cone components, or near the
intersection between components. The correlation between the sense of circular
polarization and the sense of position angle variation for conal-double pulsars
is confirmed with a much large database. Circular polarization of some pulsars
has clear changes with frequency. Circular polarization of millisecond pulsars
is marginally different from that of normal pulsars.


title:
A Unified Fitting of HI and HeII Ly\alpha Transmitted Flux of QSO HE2347
  with LCDM Hydrodynamic Simulations

abstract:
  Using cosmological hydrodynamic simulations of the LCDM model, we present a
comparison between the simulation sample and real data sample of HI and HeII
Ly\alpha transmitted flux in the absorption spectra of the QSO HE2347-4342. The
LCDM model is successful in simultaneously explaining the statistical features
of both HI and HeII Ly\alpha transmitted flux. It includes: 1.) the power
spectra of the transmitted flux of HI and HeII can be well fitted on all scales
> 0.28h^{-1} Mpc for H, and > 1.1h^{-1} Mpc for He; 2.) the Doppler parameters
of absorption features of HeII and HI are found to be turbulent-broadening; 3.)
the ratio of HeII to HI optical depths are substantially scattered, due to the
significant effect of noise. A large part of the \eta-scatter is due to the
noise in the HeII flux. However, the real data contain more low-\eta events
than simulation sample. This discrepancy may indicate that the mechanism
leading extra fluctuations upon the simulation data, such as a fluctuating UV
radiation background, is needed. Yet, models of these extra fluctuations should
satisfy the constraints: 1.) if the fluctuations are Gaussian, they should be
limited by the power spectra of observed HI and HeII flux; 2.) if the
fluctuations are non-Gaussian, they should be limited by the observed
non-Gaussian features of the HI and HeII flux.


title:
High energy diffuse gamma-ray emission of the galactic disk and Galactic
  Cosmic-Ray spectra

abstract:
  Observations of diffuse Galactic gamma-ray spectrum by the EGRET instrument
reveal an excess above ~ 1 GeV over the expected gamma-ray spectrum calculated
under the assumption that the locally observed cosmic-ray (CR) spectra
represent the galactic CR spectra. Assuming that Galactic CRs of energy below ~
100 TeV are accelerated by supernova remnant (SNR) shock waves and that the
shock compression ratio is SNR age dependent, the average source injection
spectra from an ensemble of SNRs is calculated both in the inner (330<l<30) and
outer (30<l<330) regions of the galaxy. The calculation considers the SNR age
distribution in the galaxy. Injecting these spectra in the galaxy and using a
3-D convection-diffusion equation, the CR electrons and protons spectra in the
two galactic regions are obtained and their spectra in the galactic disk are
found to be flatter than the observed CR spectra. The diffuse gamma-ray
spectrum produced by the interaction of these galactic CRs with the ISM and
ISRFs is compared with the experimental data in both the galactic regions.
Furthermore, the steepening of the observed local CR spectra from the galactic
disk CR spectra are discussed by propagating local CRs having a source spectrum
derived using local SNR age distribution (SNRs located within 1.5 kpc from the
Sun), for a diffusion coefficient D_0 ~ 0.3\times 10^{27} cm^2 s^{-1} in the
local region which is much less than the typical value in the galaxy D_0 ~
(1-10)\times 10^{28} cm^2 s^{-1}. The results obtained in this paper support
the SNR origin of galactic CRs.


title:
CB17: Inferring the dynamical history of a prestellar core with
  chemo-dynamical models

abstract:
  We present a detailed theoretical study of the isolated Bok globule CB17
(L1389) based on spectral maps of CS, HCO$^+$, C$^{18}$O, C$^{34}$S, and
H$^{13}$CO$^+$ lines. A phenomenological model of prestellar core evolution, a
time-dependent chemical model, and a radiative transfer simulation for
molecular lines are combined to reconstruct the chemical and kinematical
structure of this core. We developed a general criterion that allows to
quantify the difference between observed and simulated spectral maps. By
minimizing this difference, we find that very high and very low values of the
effective sticking probability $S$ are not appropriate for the studied
prestellar core. The most probable $S$ value for CB17 is 0.3--0.5. The spatial
distribution of the intensities and self-absorption features of optically thick
lines is indicative of UV irradiation of the core. By fitting simultaneously
optically thin and optically thick transitions, we isolate the model that
reproduces all the available spectral maps to a reasonable accuracy. The line
asymmetry pattern in CB17 is reproduced by a combination of infall, rotation,
and turbulent motions with velocities $\sim0.05$ km s$^{-1}$, $\sim0.1$ km
s$^{-1}$, and $\sim0.1$ km s$^{-1}$, respectively. These parameters corresponds
to energy ratios $E_{\rm rot}/E_{\rm grav}\approx0.03$, $E_{\rm therm}/E_{\rm
grav}\approx0.8$, and $E_{\rm turb}/E_{\rm grav}\approx0.05$ (the rotation
parameters are determined for $i=90^\circ$). The chemical age of the core is
about 2 Myrs. In particular, this is indicated by the central depletion of CO,
CS, and HCO$^+$. Based on the angular momentum value, we argue that the core is
going to fragment, i.e., to form a binary (multiple) star. (abridged)


title:
Early and Late Transient Cosmic Acceleration due to Curvature Inspired
  Dark Energy

abstract:
  It is obtained that dark energy emerges from higher-derivative gravity with
anon-linear terms proportional to $R^2$ and $R^3$ with $R$ being the Ricci
scalar curvature. Interestingly, it is found that the universe begins with
acceleration, which continues for a short period. Later on,it decelerates
driven by radiation and subsequently by matter. Two components of dark energy
are found here.In the early universe, dark energy mimics quintessence giving
high vlue of initial density $\sim 10^{75} {\rm GeV}^4$ at Planck scale. But,
in the late universe, dark energy behaves like phantom giving current value of
its density and causing late acceleration for some time. Thereafter,
deceleration driven by matter resumes.Thus, two components of dark energy are
obtained here (i) quintessence-like in the early universe and (ii)phantom-like
in the late universe. Moreover, it is interesting to see acceleration being a
transient phenomenon in early as well as late universe.


title:
Dark matter density profiles: A comparison of nonextensive theory with
  N-body simulations

abstract:
  Density profiles of simulated galaxy cluster-sized dark matter haloes are
analysed in the context of a recently introduced nonextensive theory of dark
matter and gas density distributions. Nonextensive statistics accounts for
long-range interactions in gravitationally coupled systems and is derived from
the fundamental concept of entropy generalisation. The simulated profiles are
determined down to radii of ~1% of R_200. The general trend of the relaxed,
spherically averaged profiles is accurately reproduced by the theory. For the
main free parameter kappa, measuring the degree of coupling within the system,
and linked to physical quantities as the heat capacity and the polytropic index
of the self-gravitating ensembles, we find a value of -15. The significant
advantage over empirical fitting functions is provided by the physical content
of the nonextensive approach.


title: Non Thermal Features in the Cosmic Neutrino Background

abstract:
  I review some of the basic information on the Cosmic Neutrino Background
momentum distribution. In particular, I discuss how present data from several
cosmological observables such as Big Bang Nucleosynthesis, Cosmic Microwave
Background and Large Scale Structure power spectrum constrain possible
deviations from a standard Fermi-Dirac thermal distribution.


title: SCUBA observations of the Horsehead Nebula - what did the horse swallow?

abstract:
  We present observations taken with SCUBA on the JCMT of the Horsehead Nebula
in Orion (B33), at wavelengths of 450 and 850 \mum. We see bright emission from
that part of the cloud associated with the photon-dominated region (PDR) at the
`top' of the horse's head, which we label B33-SMM1. We characterise the
physical parameters of the extended dust responsible for this emission, and
find that B33-SMM1 contains a more dense core than was previously suspected. We
compare the SCUBA data with data from the Infrared Space Observatory (ISO) and
find that the emission at 6.75-\mum is offset towards the west, indicating that
the mid-infrared emission is tracing the PDR while the submillimetre emission
comes from the molecular cloud core behind the PDR. We calculate the virial
balance of this core and find that it is not gravitationally bound but is being
confined by the external pressure from the HII region IC434, and that it will
either be destroyed by the ionising radiation, or else may undergo triggered
star formation. Furthermore we find evidence for a lozenge-shaped clump in the
`throat' of the horse, which is not seen in emission at shorter wavelengths. We
label this source B33-SMM2 and find that it is brighter at submillimetre
wavelengths than B33-SMM1. SMM2 is seen in absorption in the 6.75-\mum ISO
data, from which we obtain an independent estimate of the column density in
excellent agreement with that calculated from the submillimetre emission. We
calculate the stability of this core against collapse and find that it is in
approximate gravitational virial equilibrium. This is consistent with it being
a pre-existing core in B33, possibly pre-stellar in nature, but that it may
also eventually undergo collapse under the effects of the HII region.


title:
The Build-up of the Red Sequence in the galaxy cluster MS1054-0321 at
  z=0.831

abstract:
  Using one of the deepest datasets available, we determine that the red
sequence of the massive cluster MS1054-0321 at z=0.831 is well populated at all
studied magnitudes, showing no deficit of faint (down to M^*+3.5) red galaxies:
the faint end of the colour-magnitude relation is neither empty nor
underpopulated. The effect is quantified by the computation of the luminosity
function (LF) of red galaxies. We found a flat slope, showing that the
abundance of red galaxies is similar at faint and at intermediate magnitudes.
Comparison with present-day and z~0.4 LFs suggests that the slope of the LF is
not changed, within the errors, between z=0.831 and z=0. Therefore, the
analysis of the LF shows no evidence for a decreasing (with magnitude or
redshift) number of faint red galaxies. The presence of faint red galaxies in
high redshift clusters disfavours scenarios where the evolution of red galaxies
is mass-dependent, because the mass dependency should differentially
depauperate the red sequence, while the MS1054-0321 colour-magnitude relation
is populated as in nearby clusters and as in z~0.4 clusters. The presence of
abundant faint red galaxies in the high redshift cluster MS1054-0321 restricts
the room for allocating descendants of Butcher-Oemler galaxies, because they
should change the faint end slope of the LF of red galaxies, while instead the
same faint end slopes are observed in MS1054-0321, at z~0 and at z~0.4. In the
rich MS1054-0321 cluster, the colour-magnitude relation seems to be fully in
place at z=0.831 and therefore red galaxies of all magnitudes were wholly
assembled at higher redshift.


title: A fossil galaxy cluster; an X-ray and optical study of RX J1416.4+2315

abstract:
  We present a detailed X-ray and optical study of a distant fossil system RX
J1416.4+2315 (z=0.13), combining Chandra and XMM-Newton observations, optical
photometry and spectroscopy. X-ray emitting hot gas imaged by both the Chandra
and XMM-Newton shows a globally relaxed spatial distribution, supporting the
idea that fossil groups are old galaxy systems with no recent mergers. However,
the diffuse X-ray emission shows signs of asymmetries in the core of the
system. With a mean gas temperature of ~ 4.0 keV and total gravitational mass
of 3.1 x 10^14 solar mass, within the virial radius, this is better described
as a fossil galaxy cluster rather than a fossil group. The temperature profile
shows no sign of a significant cooler core despite a cooling time dropping to 5
Gyr within the resolved core. We find a mass concentration parameter c_200 ~ 11
which is relatively high for a cluster of this mass, indicative of an early
formation epoch. Using the spectroscopically identified cluster members we
present the galaxy luminosity function for this fossil system. We measure the
velocity dispersion of the galaxies to be ~ 700 km/s based on 18 confirmed
members. The dynamical mass is nearly twice the total gravitational mass
derived from the X-ray analysis. The measured R-band mass-to-light ratio,
within the virial radius, is ~ 440 M/L (solar) which is not unusual for
clusters of galaxies. The central giant elliptical galaxy has discy isophotes
and spectral features typical of elliptical galaxies.


title: Mid-infrared spectroscopy of carbon stars in the Small Magellanic Cloud

abstract:
  We have observed a sample of 36 objects in the Small Magellanic Cloud (SMC)
with the Infrared Spectrometer on the Spitzer Space Telescope. Nineteen of
these sources are carbon stars. An examination of the near- and mid-infrared
photometry shows that the carbon-rich and oxygen-rich dust sources follow two
easily separated sequences. A comparison of the spectra of the 19 carbon stars
in the SMC to spectra from the Infrared Space Observatory (ISO) of carbon stars
in the Galaxy reveals significant differences. The absorption bands at 7.5 um
and 13.7 um due to C2H2 are stronger in the SMC sample, and the SiC dust
emission feature at 11.3 um is weaker. Our measurements of the MgS dust
emission feature at 26-30 um are less conclusive, but this feature appears to
be weaker in the SMC sample as well. All of these results are consistent with
the lower metallicity in the SMC. The lower abundance of SiC grains in the SMC
may result in less efficient carbon-rich dust production, which could explain
the excess C2H2 gas seen in the spectra. The sources in the SMC with the
strongest SiC dust emission tend to have redder infrared colors than the other
sources in the sample, which implies more amorphous carbon, and they also tend
to show stronger MgS dust emission. The weakest SiC emission features tend to
be shifted to the blue; these spectra may arise from low-density shells with
large SiC grains.


title: The UKIRT Infrared Deep Sky Survey Early Data Release

abstract:
  This paper defines the UKIRT Infrared Deep Sky Survey (UKIDSS) Early Data
Release (EDR). UKIDSS is a set of five large near-infra-red surveys defined by
Lawrence et al. (2006), being undertaken with the UK Infra-red Telescope
(UKIRT) Wide Field Camera (WFCAM). The programme began in May 2005 and has an
expected duration of seven years. Each survey uses some or all of the broadband
filter complement ZYJHK. The EDR is the first public release of data to the
European Southern Observatory (ESO) community. All worldwide releases occur
after a delay of 18 months from the ESO release. The EDR provides a small
sample dataset, ~50 sq.deg (about 1% of the whole of UKIDSS), that is a lower
limit to the expected quality of future survey data releases. In addition, an
EDR+ dataset contains all EDR data plus extra data of similar quality, but for
areas not observed in all of the required filters (amounting to ~220 sq.deg).
The first large data release, DR1, will occur in mid-2006. We provide details
of the observational implementation, the data reduction, the astrometric and
photometric calibration, and the quality control procedures. We summarise the
data coverage and quality (seeing, ellipticity, photometricity, depth) for each
survey and give a brief guide to accessing the images and catalogues from the
WFCAM Science Archive.


title:
Near-Infrared and Optical Luminosity Functions from the 6dF Galaxy
  Survey

abstract:
  Luminosity functions and their integrated luminosity densities are presented
for the 6dF Galaxy Survey (6dFGS). This ongoing survey ultimately aims to
measure around 150,000 redshifts and 15,000 peculiar velocities over almost the
entire southern sky at |b|>10 deg. The main target samples are taken from the
2MASS Extended Source Catalog and the SuperCOSMOS Sky Survey catalogue, and
comprise 138,226 galaxies complete to (K, H, J, rF, bJ) = (12.75, 13.00, 13.75,
15.60, 16.75). These samples are comparable in size to the optically-selected
Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey samples, and improve on
recent near-infrared-selected redshift surveys by more than an order of
magnitude in both number and sky coverage. The partial samples used in this
paper contain a little over half of the total sample in each band and are ~90
percent complete.
  Luminosity distributions are derived using the 1/Vmax, STY and SWML
estimators, and probe 1 to 2 absolute magnitudes fainter in the near-infrared
than previous surveys. The effects of magnitude errors, redshift incompleteness
and peculiar velocities have been taken into account and corrected throughout.
Generally, the 6dFGS luminosity functions are in excellent agreement with those
of similarly-sized surveys. Our data are of sufficient quality to demonstrate
that a Schechter function is not an ideal fit to the true luminosity
distribution, due to its inability to simultaneously match the faint end slope
and rapid bright end decline. Integrated luminosity densities from the 6dFGS
are consistent with an old stellar population and moderately declining star
formation rate.


title:
Evolution of magnetic fields in stars across the upper main sequence: I.
  Catalogue of magnetic field measurements with FORS1 at the VLT

abstract:
  To properly understand the physics of Ap and Bp stars it is particularly
important to identify the origin of their magnetic fields. For that, an
accurate knowledge of the evolutionary state of stars that have a measured
magnetic field is an important diagnostic. Previous results based on a small
and possibly biased sample suggest that the distribution of magnetic stars with
mass below 3 M_sun in the H-R diagram differs from that of normal stars in the
same mass range (Hubrig et al. 2000). In contrast, higher mass magnetic Bp
stars may well occupy the whole main-sequence width (Hubrig, Schoeller & North
2005). In order to rediscuss the evolutionary state of upper main sequence
magnetic stars, we define a larger and bias-free sample of Ap and Bp stars with
accurate Hipparcos parallaxes and reliably determined longitudinal magnetic
fields. We used FORS1 at the VLT in its spectropolarimetric mode to measure the
magnetic field in chemically peculiar stars where it was unknown or poorly
known as yet. In this first paper we present our results of the mean
longitudinal magnetic field measurements in 136 stars. Our sample consists of
105 Ap and Bp stars, two PGa stars, 17 HgMn stars, three normal stars, and nine
SPB stars. A magnetic field was for the first time detected in 57 Ap and Bp
stars, in four HgMn stars, one PGa star, one normal B-type star and four SPB
stars.


title:
An Atomic and Molecular Study of the Interstellar Medium Around the SNR
  RCW 103

abstract:
  We report on the detection of HCO+ and 12CO emission in the rotational
transition J=1-0 in the vicinity of the shock front at the southern border of
the supernova remnant RCW 103, where previous infrared observations suggest an
interaction with a molecular cloud. The observations were carried out with the
Australian Millimeter Radiotelescope at Mopra. We observed a depletion of HCO+
behind the supernova shock front. In addition, we studied the interstellar
medium over an extended region towards RCW 103 based on archival 21 cm HI line
observations from the Australia Telescope Compact Array (ATCA) and the Parkes
Telescope. No atomic gas is observed in emission in coincidence with the
molecular feature. This absence is interpreted in terms of self absorption
processes.


title:
The white dwarf luminosity function. I. Statistical errors and
  alternatives

abstract:
  Over the years, several methods have been proposed to compute galaxy
luminosity functions, from the most simple ones -counting sample objects inside
a given volume- to very sophisticated ones -like the C- method, the STY method
or the Choloniewski method, among others. However, only the V/Vmax method is
usually employed in computing the white dwarf luminosity function and other
methods have not been applied so far to the observational sample of
spectroscopically identified white dwarfs. Moreover, the statistical
significance of the white dwarf luminosity function has also received little
attention and a thorough study still remains to be done. In this paper we
study, using a controlled synthetic sample of white dwarfs generated using a
Monte Carlo simulator, which is the statistical significance of the white dwarf
luminosity function and which are the expected biases. We also present a
comparison between different estimators for computing the white dwarf
luminosity function. We find that for sample sizes large enough the V/Vmax
method provides a reliable characterization of the white dwarf luminosity
function, provided that the input sample is selected carefully. Particularly,
the V/Vmax method recovers well the position of the cut-off of the white dwarf
luminosity function. However, this method turns out to be less robust than the
Choloniewski method when the possible incompletenesses of the sample are taken
into account. We also find that the Choloniewski method performs better than
the V/Vmax method in estimating the overall density of white dwarfs, but misses
the exact location of the cut-off of the white dwarf luminosity function.


title: Gravitational cooling of self-gravitating Bose-Condensates

abstract:
  Equilibrium configurations for a self-gravitating scalar field with
self-interaction are constructed. The corresponding Schr\"odinger-Poisson (SP)
system is solved using finite differences assuming spherical symmetry. It is
shown that equilibrium configurations of the SP system are late-time attractor
solutions for initially quite arbitrary density profiles, which relax and
virialize through the emission of scalar field bursts; a process dubbed
gravitational cooling. Among other potential applications, these results
indicate that scalar field dark matter models (in its different flavors)
tolerate the introduction of a self-interaction term in the SP equations. This
study can be useful in exploring models in which dark matter in galaxies is not
point-like.


title: The 1-1000 micron SEDs of far-infrared galaxies

abstract:
  Galaxies selected at 170um by the ISO FIRBACK survey represent the brightest
\~10% of the Cosmic Infrared Background. Examining their nature in detail is
therefore crucial for constraining models of galaxy evolution. Here we combine
Spitzer archival data with previous near-IR, far-IR, and sub-mm observations of
a representative sample of 22 FIRBACK galaxies spanning three orders of
magnitude in infrared luminosity. We fit a flexible, multi-component, empirical
SED model of star-forming galaxies designed to model the entire ~1-1000um
wavelength range. The fits are performed with a Markov Chain Monte Carlo (MCMC)
approach, allowing for meaningful uncertainties to be derived. This approach
also highlights degeneracies such as between Td and beta, which we discuss in
detail. From these fits and standard relations we derive: L_IR, L_PAH, SFR,
tau_V, M_star, M_dust, Td, and beta. We look at a variety of correlations
between these and combinations thereof in order to examine the physical nature
of these galaxies. Our conclusions are supplemented by morphological
examination of the sources, and comparison with local samples. We find the bulk
of our sample to be consistent with fairly standard size and mass disk galaxies
with somewhat enhanced star-formation relative to local spirals, but likely not
bona fide starbursts. A few higher-z LIGs and ULIGs are also present, but
contrary to expectation, they are weak mid-IR emitters and overall are
consistent with star-formation over an extended cold region rather than
concentrated in the nuclear regions. We discuss the implications of this study
for understanding populations detected at other wavelengths, such as the bright
850um SCUBA sources or the faint Spitzer 24um sources.


title: Small Scale Anisotropy Predictions for the Auger Observatory

abstract:
  We study the small scale anisotropy signal expected at the Pierre Auger
Observatory in the next 1, 5, 10, and 15 years of operation, from sources of
ultra-high energy (UHE) protons. We numerically propagate UHE protons over
cosmological distances using an injection spectrum and normalization that fits
current data up to $\sim 10^{20}\eV$. We characterize possible sources of
ultra-high energy cosmic rays (UHECRs) by their mean density in the local
Universe, $\bar{\rho} = 10^{-r}$ Mpc$^{-3}$, with $r$ between 3 and 6.
  These densities span a wide range of extragalactic sites for UHECR sources,
from common to rare galaxies or even clusters of galaxies. We simulate 100
realizations for each model and calculate the two point correlation function
for events with energies above $4 \times 10^{19}\eV$ and above $10^{20}\eV$, as
specialized to the case of the Auger telescope. We find that for $r\ga 4$,
Auger should be able to detect small scale anisotropies in the near future.
Distinguishing between different source densities based on cosmic ray data
alone will be more challenging than detecting a departure from isotropy and is
likely to require larger statistics of events. Combining the angular
distribution studies with the spectral shape around the GZK feature will also
help distinguish between different source scenarios.


title:
Integrated specific star formation rates of galaxies, groups, and
  clusters: A continuous upper limit with stellar mass?

abstract:
  Aims: We investigate the build-up of stellar mass through star formation in
field galaxies, galaxy groups, and clusters in order to better understand the
physical processes regulating star formation in different haloes.
  Methods: In order to do so we relate ongoing star formation activity to the
stellar mass by studying the integrated specific star formation rate (SSFR),
defined as the star-formation rate per unit stellar mass, as a function of
integrated stellar mass for samples of field galaxies, groups of galaxies, and
galaxy clusters at 0.18 < z < 0.85. The star formation rate (SFR) is derived
from the ultraviolet continuum for the galaxies and group members, and from
emission line fluxes for the cluster galaxies. The stellar masses are computed
from multi-band photometry including the near-infrared bands for the galaxies
and groups, and from the dynamical mass for the cluster sample.
  Results: For the first time, integrated SSFRs for clusters and groups are
presented and related to the SSFRs of field galaxies. Tentatively, we find a
continuous upper limit for galaxies, groups, and clusters in the SSFR-stellar
mass plane over seven orders of magnitude in stellar mass. This might indicate
that the physical processes which control star formation in dark matter haloes
of different mass have the same scaling with mass over a wide range of masses
from dwarf galaxies to massive clusters of galaxies.


title: Updating reionization scenarios after recent data

abstract:
  The recent release of data on (i) high redshift source counts from NICMOS
HUDF, and (ii) electron scattering optical depth from 3-year WMAP, require a
re-examination of reionization scenarios. Using an improved self-consistent
model, based on Choudhury & Ferrara (2005), we determine the range of
reionization histories which can match a wide variety of data sets
simultaneously. From this improved analysis we find that hydrogen reionization
starts around z = 15, driven by the metal-free stars (with normal Salpeter-like
IMF), and is 90% complete by z = 10. The photoionizing power of PopIII stars
fades for z < 10 because of the concomitant action of radiative and chemical
feedbacks, which causes the reionization process to stretch considerably and to
end only by z = 6. The combination of different data sets still favours a
non-zero contribution from metal-free stars, forming with efficiencies > 2%.


title:
Diffuse Gamma Rays from the Galactic Plane: Probing the "GeV Excess" and
  Identifying the "TeV Excess"

abstract:
  Pion decay gamma rays have long been recognized as a unique signature of
hadronic cosmic rays and their interactions with the interstellar medium. We
present a model-independent way of constraining this signal with observations
of the Galactic Plane in diffuse gamma rays. We combine detections by the EGRET
instrument at GeV energies and the Milagro Cherenkov detector at TeV energies
with upper limits from KASCADE and CASA-MIA ground arrays at PeV energies. Such
a long "lever arm", spanning at least six orders of magnitude in energy,
reveals a "TeV excess" in the diffuse Galactic Plane gamma-ray spectrum. While
the origin of this excess is unknown, it likely implies also enhanced TeV
neutrino fluxes, significantly improving the prospects for their detection. We
show that unresolved point sources are a possible source of the TeV excess. In
fact, the spectra of the unidentified EGRET sources in the Milagro region must
break between ~10 GeV and ~1 TeV to avoid strongly overshooting the Milagro
measurement; this may have important implications for cosmic-ray acceleration.
  Finally, we use our approach to examine the recent suggestion that
dark-matter annihilation may account for the observed excess in diffuse
Galactic gamma-rays detected by EGRET at energies above 1 GeV. Within our
model-independent approach, current data cannot rule this possibility in or
out; however we point out how a long "lever arm" can be used to constrain the
pionic gamma-ray component and in turn limit the "GeV excess" and its possible
sources. Experiments such as HESS and MAGIC, and the upcoming VERITAS and
GLAST, should be able to finally disentangle the main sources of the Galactic
gamma rays.


title: Exploring brown dwarf disks: A 1.3 mm survey in Taurus

abstract:
  We have carried out sensitive 1.3 mm observations of 20 young brown dwarfs in
the Taurus star-forming region, representing the largest sample of young
substellar objects targeted in a deep millimeter continuum survey to date.
Under standard assumptions, the masses of brown dwarf disks range from ~<0.4 to
several Jupiter masses. Their relative disk masses are comparable to those
derived for coeval low-mass stars: most of them are in the ~<1-5% range, and
there is no clear change of relative disk mass with object mass from 0.015 to 3
solar masses. Specifically, we do not find evidence for disk truncation, as
would be expected in the ejection scenario for brown dwarf origin, although the
signature of ejection may be hidden in our non-detections. We use the derived
mm fluxes, complemented by mid-infrared data from the Spitzer Space Telescope
and ground-based near-infrared images, to construct spectral energy
distributions (SEDs) for six of our sources, and model those SEDs with a Monte
Carlo radiative transfer code. While the model fits are by no means unique,
they allow us to investigate disk properties such as the degree of flaring and
minimum radii. In several cases, we find that the SEDs in the mid-infrared
exhibit lower flux levels than predicted by hydrostatic models, implying dust
settling to the disk midplane. What's more, at least 25% of our targets are
likely to have disks with radii >10 AU; models with smaller disks cannot
reproduce the mm fluxes even if they are very massive. This finding is in
contrast to the results of some simulations of the ejection scenario for brown
dwarf formation that suggest only ~5% of ejected objects would harbor disks
larger than 10 AU. Our findings imply that ejection is probably not the
dominant formation process, but may still be relevant for some brown dwarfs.


title: Non-thermal emission from early-type stars

abstract:
  Massive, early-type stars deposit energy and momentum in the interstellar
medium through dense, supersonic winds. These objects are one of the most
important sources of ionising radiation and chemical enrichment in the Galaxy.
The physical conditions in the winds give rise to thermal and non-thermal
emission, detectable from radio to gamma rays. In this report the relevant
radiation processes will be described and studies on particular systems will be
presented, discussing the information provided by multifrequency observations.
Future steps aiming at understanding the stellar wind phenomenon as a whole
will be outlined.


title:
Probing Dynamics of Dark Energy with Supernova, Galaxy Clustering and
  the Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations

abstract:
  Using the Markov chain Monte Carlo (MCMC) method we perform a global analysis
constraining the dynamics of dark energy in light of the supernova (Riess
"Gold" samples), galaxy clustering (SDSS 3D power spectra and SDSS lyman-\alpha
forest information) and the latest three-year Wilkinson Microwave Anisotropy
Probe (WMAP) observations. We have allowed the dark energy equation of state to
get across -1 and pay particular attention to the effects when incorrectly
neglecting dark energy perturbations. We find the parameter space of dynamical
dark energy is now well constrained and neglecting dark energy perturbations
will make the parameter space significantly smaller. Dynamical dark energy
model where the equation of state crosses -1 is mildly favored and the standard
\LambdaCDM model is still a good fit to the current data.


title:
Constraining dark matter halo profiles and galaxy formation models using
  spiral arm morphology. I. Method outline

abstract:
  We investigate the use of spiral arm pitch angles as a probe of disk galaxy
mass profiles. We confirm our previous result that spiral arm pitch angles (P)
are well-correlated with the rate of shear (S) in disk galaxy rotation curves,
by using a much larger sample (51 galaxies) than used previously (17 galaxies).
We use this correlation to argue that imaging data alone can provide a powerful
probe of galactic mass distributions out to large lookback times. In contrast
to previous work, we show that observed spiral arm pitch angles are similar
when measured in the optical (at 0.4 um) and the near-infrared (at 2.1 um) with
a mean difference of 2.3+/-2.7 degrees. This is then used to strengthen the
known correlation between P and S using B-band images. We then use two example
galaxies to demonstrate how an inferred shear rate coupled with a bulge-disk
decomposition model and a Tully-Fisher derived velocity normalization can be
used to place constraints on a galaxy's baryon fraction and dark matter halo
profile. We show that ESO 582-G12, a galaxy with a high shear rate (slightly
declining rotation curve) at ~10 kpc, favors an adiabatically contracted halo,
with high initial NFW concentration (c_vir > 16) and a high fraction of halo
baryons in the form of stars (~15-40%). In contrast, IC 2522 has a low shear
rate (rising rotation curve) at ~10 kpc and favors non-adiabatically contracted
models with low NFW concentrations (c_vir ~ 2-8) and a low stellar baryon
fraction <10%.


title: Quasar Microlensing: when compact masses mimic smooth matter

abstract:
  The magnification induced by gravitational microlensing is sensitive to the
size of a source relative to the Einstein radius, the natural microlensing
scale length. This paper investigates the effect of source size in the case
where the microlensing masses are distributed with a bimodal mass function,
with solar mass stars representing the normal stellar masses, and smaller
masses (down to $8.5\times 10^{-5}$M$_\odot$) representing a dark matter
component. It is found that there exists a critical regime where the dark
matter is initially seen as individual compact masses, but with an increasing
source size the compact dark matter acts as a smooth mass component. This study
reveals that interpretation of microlensing light curves, especially claims of
small mass dark matter lenses embedded in an overall stellar population, must
consider the important influence of the size of the source.


title: Dark Energy in an Astrophysical Context

abstract:
  We explore local consequences of a non-zero cosmological constant on
astrophysical structures. We find that the effects are not only sensitive to
the density of the configurations but also to the geometry. For non-homogeneous
configurations, we calculate the effects for a polytropic configurations and
the isothermal sphere. Special emphasis is put on the fact that the
cosmological constant sets certain scales of length, time, mass and density.
Sizable effects are established for non spherical systems such as elliptical
galaxy clusters where the effects of $\Lambda$ are growing with the flatness of
the system. The equilibrium of rotating ellipsoids is modified and the
cosmological constant allows new configurations of equilibrium.


title:
Type II Quasars from the Sloan Digital Sky Survey: V. Imaging host
  galaxies with the Hubble Space Telescope

abstract:
  Type II quasars are luminous Active Galactic Nuclei whose centers are
obscured by large amounts of gas and dust. In this paper we present 3-band HST
images of nine type II quasars with redshifts 0.2 < z < 0.4 selected from the
Sloan Digital Sky Survey based on their emission line properties. The intrinsic
luminosities of these AGN are estimated to be -24 > M_B > -26, but optical
obscuration allows their host galaxies to be studied unencumbered by bright
nuclei. Each object has been imaged in three continuum filters (`UV', `blue'
and `yellow') placed between the strong emission lines. The spectacular, high
quality images reveal a wealth of details about the structure of the host
galaxies and their environments. Six of the nine galaxies in the sample are
ellipticals with de Vaucouleurs light profiles, one object has a well-defined
disk component and the remaining two have marginal disks. Stellar populations
of type II quasar hosts are more luminous (by a median of 0.3-0.7 mag,
depending on the wavelength) and bluer (by about 0.4 mag) than are M* galaxies
at the same redshift. When smooth fits to stellar light are subtracted from the
images, we find both positive and negative residuals that become more prominent
toward shorter wavelengths. We argue that the negative residuals are due to
kpc-scale dust obscuration, while most positive residuals are due to the light
from the nucleus scattered off interstellar material in the host galaxy.
Scattered light makes a significant contribution to the broad band continuum
emission and can be the dominant component of the extended emission in the UV
in extreme cases.


title: HI in Local Group analogs: what does it tell us about galaxy formation?

abstract:
  We present the results of our HI survey of six loose groups of galaxies
analogous to the Local Group. The survey was conducted using the Parkes
telescope and the Australia Telescope Compact Array to produce a census of all
the gas-rich galaxies and potential analogs to the high-velocity clouds (HVCs)
within these groups down to M(HI)<10^7 M(sun) as a test of models of galaxy
formation. We present the HI mass function and halo mass function for these
analogous groups and compare them with the Local Group and other environments.
We also demonstrate that our non-detection of HVC analogs in these groups
implies that they must have low HI masses and be clustered tightly around
galaxies, including around our own Milky Way, and are not distributed
throughout the Local Group.


title:
Jet Sideways Expansion Effect on Estimating the Gamma-Ray Burst
  Efficiency

abstract:
  The high efficiency of converting kinetic energy into gamma-rays estimated
with late-time afterglows in Gamma-Ray Burst (GRB) phenomenon challenges the
commonly accepted internal-shock model. However, the efficiency is still highly
uncertain because it is sensitive to many effects. In this Letter we study the
sideways expansion effect of jets on estimating the efficiency. We find that
this effect is considerable, reducing the efficiency by a factor of $\sim0.5$
for typical parameters, when the afterglow data $\sim 10$ hr after the GRB
trigger are used to derive the kinetic energy. For a more dense circumburst
medium, this effect is more significant. As samples, taking this effect into
account, we specifically calculate the efficiency of two bursts whose
parameters were well constrained. Almost the same results are derived. This
suggests that the sideways expansion effect should be considered when the GRB
efficiency is estimated with the late afterglow data.


title:
Z-machine science other than CO - scientific and technical prospects for
  very wide band-width radio and (sub)millimeter-wavelength spectroscopy

abstract:
  While clearly the main scientific targets of ''z-machines" will be redshifted
lines of carbon monoxide, there also exist other interesting applications. Here
scientific and technological aspects of observing lines from CO and other
species at high redshift and in the local universe are discussed as are the
limitations of such efforts and prospects for the future.


title: 15 years of VLBI observations of two compact radio sources in Messier 82

abstract:
  We present the results of a second epoch of 18cm global Very Long-Baseline
Interferometry (VLBI) observations, taken on 23 February 2001, of the central
kiloparsec of the nearby starburst galaxy Messier 82. These observations
further investigate the structural and flux evolution of the most compact radio
sources in the central region of M82. The two most compact radio objects in M82
have been investigated (41.95+575 and 43.31+592). Using this recent epoch of
data in comparison with our previous global VLBI observations and two earlier
epochs of European VLBI Network observations we measure expansion velocities in
the range of 1500-2000km/s for 41.95+575, and 9000-11000km/s for 43.31+592
using various independent methods. In each case the measured remnant expansion
velocities are significantly larger than the canonical expansion velocity
(500km/s) of supernova remnants within M82 predicted from theoretical models.
  In this paper we discuss the implications of these measured expansion
velocities with respect to the high density environment that the SNR are
expected to reside in within the centre of the M82 starburst.


title:
X-ray and optical bursts and flares in YSOs: results from a 5-day
  XMM-Newton monitoring campaign of L1551

abstract:
  We present the results of a five-day monitoring campaign with XMM-Newton of
six X-ray bright young stellar objects (YSOs) in the star-forming complex L1551
in Taurus. All stars present significant variability on the five-day time
scale. Modulation of the light curve on time scales comparable with the star's
rotational period appeared to be present in the case of one weak-lined T Tauri
star. Significant spectral variations between the 2000 and the 2004
observations were detected in the (unresolved) classical T Tauri binary system
XZ Tau: a hot plasma component which was present in the X-ray spectrum in 2000
had significantly weakened in 2004. As XZ Tau N was undergoing a strong optical
outburst in 2000, which had terminated since then, we speculate on the possible
relationship between episodic, burst accretion, and X-ray heating. The
transition object HL Tau underwent a strong flare with a complex temperature
evolution, which is indicative of an event confined within a very large
magnetic structure (few stellar radii), similar to the ones found in YSOs in
the Orion Nebula Cluster.


title:
Cosmological Magnetic Field: a fossil of density perturbations in the
  early universe

abstract:
  The origin of the substantial magnetic fields that are found in galaxies and
on even larger scales, such as in clusters of galaxies, is yet unclear. If the
second-order couplings between photons and electrons are considered, then
cosmological density fluctuations, which explain the large scale structure of
the universe, can also produce magnetic fields on cosmological scales before
the epoch of recombination. By evaluating the power spectrum of these
cosmological magnetic fields on a range of scales, we show here that magnetic
fields of 10^{-18.1} gauss are generated at a 1 megaparsec scale and can be
even stronger at smaller scales (10^{-14.1} gauss at 10 kiloparsecpc). These
fields are large enough to seed magnetic fields in galaxies and may therefore
have affected primordial star formation in the early universe.


title:
Constraints on the DGP Model from Recent Supernova Observations and
  Baryon Acoustic Oscillations

abstract:
  Although there is mounting observational evidence that the expansion of our
universe is undergoing a late-time acceleration, the mechanism for this
acceleration is yet unknown. In the so-called Dvali-Gabadadze-Porrati (DGP)
model this phenomena is attributed to gravitational leakage into extra
dimensions. In this work, we mainly focus our attention to the constraints on
the model from the gold sample of type Ia supernovae (SNeIa), the first year
data from the Supernova Legacy Survey (SNLS) and the baryon acoustic
oscillation (BAO) peak found in the Sloan Digital Sky Survey (SDSS). At 99.73%
confidence level, the combination of the three databases provides
Omega_m=0.270^{+0.018}_{-0.017} and Omega_{r_c}=0.216^{+0.012}_{-0.013} (hence
a spatially closed universe with Omega_k=-0.350^{+0.080}_{-0.083}), which seems
to be in contradiction with the most recent WMAP results indicating a flat
universe. Based on this result, we also estimated the transition redshift (at
which the universe switches from deceleration to acceleration) to be 0.70 <
z_{q=0} < 1.01, at 2 sigma confidence level.


title: Galaxy Formation and SN Feedback

abstract:
  We present a Supernova (SN) feedback model that succeeds at describing the
chemical and energetic effects of SN explosions in galaxy formation
simulations. This new SN model has been coupled to GADGET-2 and works within a
new multiphase scheme which allows the description of a co-spatial mixture of
cold and hot interstellar medium phases.
  No ad hoc scale-dependent parameters are associated to these SN and
multiphase models making them particularly suited to studies of galaxy
formation in a cosmological framework. Our SN model succeeds not only in
setting a self-regulated star formation activity in galaxies but in triggering
collimated chemical-enriched galactic winds. The effects of winds vary with the
virial mass of the systems so that the smaller the galaxy, the larger the
fraction of swept away gas and the stronger the decrease in its star formation
activity. The fact that the fraction of ejected metals exceeds 60 per cent
regardless of mass, suggests that SN feedback can be the responsible mechanism
of the enrichment of the intergalactic medium to the observed levels.


title:
Curious Variables Experiment (CURVE). Variable properties of the dwarf
  nova SS UMi

abstract:
  We report on extensive photometry of the dwarf nova SS Ursae Minoris
throughout nine months of 2004. In total, we recorded two superoutbursts and 11
normal outbursts of the star. SS UMi has been known to show frequent
superoutbursts with a mean interval of 84.7 days. Our data suggest that the
interval between successive superoutbursts lengthened to 197 days, indicating
that SS UMi entered a period of untypical behavior manifested by a growth in
the quiescent magnitude of the star and a series of frequent, low-amplitude,
normal outbursts observed from July to September 2004.
  The mean superhump period derived for the April 2004 superoutburst of SS UMi
is 0.070149(16) days (101.015 min). Combining this value with an earlier
orbital period determination, we were able to derive the period excess, which
is equal to 3.5 +/- 1.6%, and estimate the mass ratio of the binary system as
equal to q=0.16 +/- 0.07.
  During the entire superoutburst, the period decreased at a rate of $\dot
P/P_{\rm sh} = -6.3(1.4) \times 10^{-5}$. However, detailed analysis of the
timings of superhump maxima seem to suggest a more complex period change, with
a decrease in the period during the first and last stages of the superoutburst
but an increase in the middle interval.


title: High-redshift, Restframe Far-infrared Selected Galaxies

abstract:
  I discuss our current understanding of the properties and nature of high
redshift, far-infrared luminous galaxies selected through their observed-frame
submillimeter emission.


title: Nuclear embedded star clusters in NGC 7582

abstract:
  We report on the discovery of several compact regions of mid-infrared
emission in the starforming circum nuclear disk of the starburst/Seyfert2
galaxy NGC7582. The compact sources do not have counterparts in the optical and
near-infrared, suggesting that they are deeply embedded in dust. We use the
[NeII]12.8 micron line emission to estimate the emission measure of the ionized
gas, which in turn is used to assess the number of ionizing photons. Two of the
brighter sources are found to have ionizing fluxes of ~2.5x10^52, whereas the
fainter ones have ~1x10^52 photons/s. Comparing with a one Myr old starburst,
we derive stellar masses in the range (3-5)x10^5 Msun, and find that the number
of O-stars in each compact source is typically (0.6-1.6)x10^3. We conclude that
the compact mid-infrared sources are likely to be young, embedded star
clusters, of which only a few are known so far. Our observation highlights the
need for high resolution mid-infrared imaging to discover and study embedded
star clusters in the proximity of active galactic nuclei.


title: The Mass of the Cosmos

abstract:
  We point out that the mass of the cosmos on gigaparsec scales can be
measured, owing to the unique geometric role of the maximum in the areal
radius. Unlike all other points on the past null cone, this maximum has an
associated mass, which can be calculated with very few assumptions about the
cosmological model, providing a measurable characteristic of our cosmos. In
combination with luminosities and source counts, it gives the bulk mass to
light ratio. The maximum is particularly sensitive to the values of the bulk
cosmological parameters. In addition, it provides a key reference point in
attempts to connect cosmic geometry with observations. We recommend the
determination of the distance and redshift of this maximum be explicitly
included in the scientific goals of the next generation of reshift surveys. The
maximum in the redshift space density provides a secondary large scale
characteristic of the cosmos.


title:
XMM-Newton observations of the complex spin pulse of the intermediate
  polar PQ~Geminorum

abstract:
  The intermediate polar PQ Geminorum shows a complex pulsation, caused by a
spinning white dwarf, which varies markedly with wavelength. We report
XMM-Newton observations, including the soft and hard X-ray bands and the first
UV lightcurves of this star. We update the ephemeris for PQ Gem allowing us to
align these data with a compilation of lightcurves from the optical to the
X-ray. Building on work by previous authors, we show how a model in which
accretion flows along skewed field lines, viewed at the correct inclination,
can explain the major features of the lightcurves in all bands. We discuss how
the skew of the field lines relates to the spinning down of the white-dwarf
rotation.


title:
The metallicities of luminous, massive field galaxies at intermediate
  redshifts

abstract:
  We derive oxygen abundances for a sample of 40 luminous (M_{B} < -19),
star-forming, mostly disk, field galaxies with redshifts in the range 0.2 < z <
0.8$, with a median of <z> = 0.45. Oxygen abundances, relative to hydrogen, of
the interstellar emitting gas are estimated by means of the empirically
calibrated strong emission line ratio technique. The derived (12+log(O/H))
values range from 8.4 to 9.0, with a median of 8.7. Twenty of these galaxies
have securely measured rotation velocities, in the range 50--244 km/s. The
measured emission line equivalent widths and diagnostic ratios for the
intermediate redshift galaxies cover similar ranges to those observed across a
large sample of local galaxies. The estimated oxygen abundances for our
luminous star-forming intermediate redshift galaxies cover the same range as
their local counterparts. However, at a given galaxy luminosity, many of our
galaxies have significantly lower oxygen abundances, i.e., $(12+log(O/H))~8.6$,
than local galaxies with similar luminosities. Interestingly, these luminous,
massive, intermediate redshift, star-forming galaxies with low oxygen
abundances exhibit physical conditions, i.e., emission line equivalent width
and ionization state, very similar to those of local faint and metal-poor
star-forming galaxies. The oxygen abundance of the interstellar gas does not
seem to correlate with the maximum rotation velocity or the emission scale
length of the parent galaxy. This suggests that there is a diversity in the
intrinsic properties of the massive field galaxy population at intermediate
redshifts (ABRIDGED).