title: SZE Signals in Cluster Models

abstract:
  The upcoming generation of SZE surveys will shed fresh light onto the study
of clusters. What will this new observational window reveal about cluster
properties? What can we learn from combining X-ray, SZE, and optical
observations? How do variations in the gas entropy profile, dark matter
concentration, accretion pressure, and intracluster medium (ICM) mass fraction
affect SZE observables? We investigate the signature of these important cluster
parameters with an analytic model of the ICM. Given the current uncertainties
in ICM physics, our approach is to span the range of plausible models motivated
by observations and a small set of assumptions. We find a tight relation
between the central Compton parameter and the X-ray luminosity outside the
cluster core, suggesting that these observables carry the same information
about the ICM. The total SZE luminosity is proportional to the thermal energy
of the gas, and is a surprisingly robust indicator of cluster mass: $L_{SZ}
\propto f_{ICM} M^{5/3}$. We show that a combination of $L_{SZ}$ and the
half-luminosity radius $r_{SZ}$ provides a measure of the potential energy of
the cluster gas, and thus we can deduce the total energy content of the ICM. We
caution that any systematic variation of the ICM mass fraction will distort the
expected $L_{SZ} - M$ calibration to be used to study the evolution of cluster
number density, and propose a technique using kSZ to constrain $f_{ICM}(M,z)$.


title: On the Decoherence of Primordial Fluctuations During Inflation

abstract:
  We study the evironment-induced decoherence of cosmological perturbations in
an inflationary background. Splitting our spectrum of perturbations into two
distinct sets characterized by their wavelengths (super and sub-Hubble), we
identify the long wavelength modes with our system and the remainder with an
environment. We examine the effects of the interactions between our system and
the environment. This interaction causes the long-wavelength modes to decohere
for realistic values of the coupling and we conclude that interactions due to
backreaction are more than sufficient to decohere the system within 60
e-foldings of inflation. This is shown explicitly by obtaining an analytic
solution to a master equation detailing the evolution of the density matrix of
the system.


title: Spitzer observations of the dusty warped disk of Centaurus A

abstract:
  Spitzer mid-infrared images of the dusty warped disk in the galaxy Centaurus
A show a parallelogram-shaped structure. We successfully model the observed
mid-infrared morphology by integrating the light from an emitting, thin, and
warped disk, similar to that inferred from previous kinematic studies. The
models with the best match to the morphology lack dust emission within the
inner 0.1 to 0.8 kpc, suggesting that energetic processes near the nucleus have
disturbed the inner molecular disk, creating a gap in the molecular gas
distribution.


title:
Absolute-Magnitude Distributions and Light Curves of Stripped-Envelope
  Supernovae

abstract:
  The absolute visual magnitudes of three Type IIb, 11 Type Ib and 13 Type Ic
supernovae (collectively known as stripped-envelope supernovae) are studied by
collecting data on the apparent magnitude, distance, and interstellar
extinction of each event. Weighted and unweighted mean absolute magnitudes of
the combined sample as well as various subsets of the sample are reported. The
limited sample size and the considerable uncertainties, especially those
associated with extinction in the host galaxies, prevent firm conclusions
regarding differences between the absolute magnitudes of supernovae of Type Ib
and Ic, and regarding the existence of separate groups of overluminous and
normal-luminosity stripped-envelope supernovae. The spectroscopic
characteristics of the events of the sample are considered. Three of the four
overluminous events are known to have had unusual spectra. Most but not all of
the normal luminosity events had typical spectra. Light curves of
stripped-envelope supernovae are collected and compared. Because SN 1994I in
M51 was very well observed it often is regarded as the prototypical Type Ic
supernova, but it has the fastest light curve in the sample. Light curves are
modeled by means of a simple analytical technique that, combined with a
constraint on E/M from spectroscopy, yields internally consistent values of
ejected mass, kinetic energy, and nickel mass.


title:
Catalog of fundamental mode RR Lyrae stars in the Galactic bulge from
  the Optical Gravitational Lensing Experiment

abstract:
  We present a catalog of 1888 fundamental-mode RR Lyrae stars detected in the
Galactic bulge fields of the second phase of the Optical Gravitational Lensing
Experiment (OGLE). The catalog includes basic parameters of the light curves,
identifications of Blazhko frequencies, V-I colors at minimum light (for most
stars), and other information for each star. We detect a high rate of incidence
of the Blazhko phenomenon (at least 27.6%), including unprecedentedly many
frequency triplets, which we attribute to our sensitive search method. We find
that the minimum light V-I color (useful as a reddening indicator) grows slowly
redder with increasing period and exhibits a star-to-star scatter of
approximately 0.07 mag. We use this color to evaluate the zero-point accuracy
of the reddening map of the Galactic bulge derived from OGLE data, and find
that in addition to low-level random errors or resolution effects (responsible
for much of the scatter), the map may systematically over-represent E(V-I) by
approximately 0.05 mag in most fields. We present reasonably robust evidence
that the RR Lyrae-to-red clump color separation is larger by 0.05--0.08 mag in
the bulge than locally, which argues for caution in the use of these stars for
reddening determinations. We consider the RR Lyrae constraint on the
Galactocentric distance, but uncertainty about the absolute magnitude
calibration leaves significant flexibility in the result. In contrast to
previous results, we robustly detect the signature of the Galactic bar in the
RR Lyrae population within the inner plus/minus 3 degrees of longitude, and we
highlight the apparent differences between the structures traced by the red
clump giants and the more metal-poor RR Lyrae stars. (abridged)


title:
The Bar-Halo Interaction - II. Secular evolution and the religion of
  N-body simulations

abstract:
  This paper explores resonance-driven secular evolution between a bar and
dark-matter halo using N-body simulations. We make direct comparisons to our
analytic theory (Weinberg & Katz 2005) to demonstrate the great difficulty that
an N-body simulation has representing these dynamics for realistic astronomical
interactions. In a dark-matter halo, the bar's angular momentum is coupled to
the central density cusp (if present) by the Inner Lindblad Resonance. Owing to
this angular momentum transfer and self-consistent re-equilibration, strong
realistic bars WILL modify the cusp profile, lowering the central densities
within about 30% of the bar radius in a few bar orbits. Past results to the
contrary (Sellwood 2006, McMillan & Dehnen 2005) may be the result of weak bars
or numerical artifacts. The magnitude depends on many factors and we illustrate
the sensitivity of the response to the dark-matter profile, the bar shape and
mass, and the galaxy's evolutionary history. For example, if the bar length is
comparable to the size of a central dark-matter core, the bar may exchange
angular momentum without changing its pattern speed significantly. We emphasise
that this apparently simple example of secular evolution is remarkably subtle
in detail and conclude that an N-body exploration of any astronomical scenario
requires a deep investigation into the underlying dynamical mechanisms for that
particular problem to set the necessary requirements for the simulation
parameters and method (e.g. particle number and Poisson solver). Simply put,
N-body simulations do not divinely reveal truth and hence their results are not
infallible. They are unlikely to provide useful insight on their own,
particularly for the study of even more complex secular processes such as the
production of pseudo-bulges and disk heating.


title: The Galactic Nature of High Velocity Cloud Complex WB

abstract:
  We have detected absorption lines from the High Velocity Cloud Complex WB in
the spectrum of the star HE1048+0231. This detection sets an upper distance
limit to the cloud of 8.8^{+2.3}_{-1.3} kpc. Non-detection (at >4 sigma
confidence) in the star HE1138-1303 at 7.7 +/- 0.2 kpc sets a probable lower
limit. The equivalent width of the CaII K line due to the HVC (114.6 +/- 4.4
mA) corresponds to a column density of 1.32 +/- 0.05 x 10^12 cm^-2. Using an HI
spectrum from the Leiden/Argentine/Bonn survey, we calculated N(CaII)/N(HI) =
81 +/- 16 x 10^-9. These distance limits imply an HI mass limit of 3.8 x 10^5
Msun < M_HI < 4.9 x 10^5 Msun. The upper distance limit imposed by these
observations shows that this HVC complex has a probable Galactic or
circum-Galactic origin. Future metallicity measurements will be able to confirm
or refute this interpretation.


title:
Gravitational microlensing of quasar Broad Line Regions: the influence
  of fractal structures

abstract:
  Recent models for the emission clouds within the Broad Line Region of quasars
suggest that they are due to transient overdensities within an overall
turbulent medium. If this were the case, the broad line emission would
spatially appear fractal, possessing structure on a range of scales. This paper
examines the influence of such fractal structure when a quasar is microlensed
by a population of intervening masses. It is found that while the highest
fractal levels can undergo significant microlensing magnification, when these
light curves are superimposed to create an emission line profile, the resultant
emission line profile remains relatively constant for physical models of the
Broad Line Region. It is concluded that the detection of the possible fractal
structure of Broad Line Regions via gravitational microlensing is not
practical.


title: The X-ray properties of young radio-loud AGN

abstract:
  We present XMM-Newton observations of a complete sample of five archetypal
young radio-loud AGN, also known Gigahertz Peaked Spectrum (GPS) sources. They
are among the brightest and best studied GPS/CSO sources in the sky, with radio
powers in the range L_{5GHz}=10^{43-44} erg/s and with 4 sources having
measured kinematic ages of 570 to 3000 yrs. All sources are detected, and have
2-10 keV luminosities from 0.5 to 4.8x10^{44} erg/s. In comparison with the
general population of radio galaxies, we find that: 1) GPS galaxies show a a
range in absorption column densities similar to other radio galaxies. We
therefore find no evidence that GPS galaxies reside in significantly more dense
circumnuclear environment, such that they could be hampered in their expansion.
2) The ratio of radio to X-ray luminosity is significantly higher than for
classical radio sources. This is consistent with an evolution scenario in which
young radio sources are more efficient radio emitters than large extended
objects at a constant accretion power. 3) Taking the X-ray luminosity of radio
sources as a measure of ionisation power, we find that GPS galaxies are
significantly underluminous in their [OIII]_{5007 Angstrom}, including a weak
trend with age. This is consistent with the fact that the Stroemgren sphere
should still be expanding in these young objects. This would mean that here we
are witnessing the birth of the narrow line region of radio-loud AGN.


title:
Collapse of Neutron Stars to Black Holes in Binary Systems: A Model for
  Short Gamma Ray Bursts

abstract:
  The accretion of ~ 0.1 -- 1 M_o of material by a neutron star through Roche
lobe overflow of its companion or through white-dwarf/neutron-star coalescence
in a low mass binary system could be enough to exceed the critical mass of a
neutron star and trigger its collapse to a black hole, leading to the
production of a short gamma-ray burst (SGRB). In this model, SGRBs would often
be found in early-type galaxies or in globular cluster environments, though
they could also be formed through stellar-wind accretion in high-mass binary
systems of star-forming galaxies. Although the collapse event is likely to be
of short (<< 1 s) duration, afterglow complexity could be produced by neutron
decoupling in the fireball and subsequent accretion of the companion remnant,
for example, the disrupted white-dwarf core.


title: Radiative Flow in a Luminous Disk

abstract:
  Radiatively-driven flow in a luminous disk is examined in the subrelativistic
regime of $(v/c)^1$, taking account of radiation transfer. The flow is assumed
to be vertical, and the gravity and gas pressure are ignored. When internal
heating is dropped, for a given optical depth and radiation pressure at the
flow base (disk ``inside''), where the flow speed is zero, the flow is
analytically solved under the appropriate boundary condition at the flow top
(disk ``surface''), where the optical depth is zero. The loaded mass and
terminal speed of the flow are both determined by the initial conditions; the
mass-loss rate increases as the initial radiation pressure increases, while the
flow terminal speed increases as the initial radiation pressure and the loaded
mass decrease. In particular, when heating is ignored, the radiative flux $F$
is constant, and the radiation pressure $P_0$ at the flow base with optical
depth $\tau_0$ is bound in the range of $2/3 < cP_0/F < 2/3 + \tau_0$. In this
case, in the limit of $cP_0/F = 2/3 + \tau_0$, the loaded mass diverges and the
flow terminal speed becomes zero, while, in the limit of $cP_0/F = 2/3$, the
loaded mass becomes zero and the terminal speed approaches $(3/8)c$, which is
the terminal speed above the luminous flat disk under an approximation of the
order of $(v/c)^1$. We also examine the case where heating exists, and find
that the flow properties are qualitatively similar to the case without heating.


title: Radiative Flow in a Luminous Disk II

abstract:
  Radiatively-driven transfer flow perpendicular to a luminous disk is examined
in the subrelativistic regime of $(v/c)^1$, taking into account the gravity of
the central object. The flow is assumed to be vertical, and the gas pressure is
ignored, while internal heating is assumed to be proportional to the gas
density. The basic equations were numerically solved as a function of the
optical depth, and the flow velocity, the height, the radiative flux, and the
radiation pressure were obtained for a given radius, an initial optical depth,
and initial conditions at the flow base (disk ``inside''), whereas the
mass-loss rate was determined as an eigenvalue of the boundary condition at the
flow top (disk ``surface''). For sufficiently luminous cases, the flow
resembles the case without gravity. For less-luminous cases, however, the flow
velocity decreases, and the flow would be impossible due to the existence of
gravity in the case that the radiative flux is sufficiently small. Application
to a supercritical accretion disk with mass loss is briefly discussed.


title:
Novel Methods for Predicting Photometric Redshifts from Broad Band
  Photometry using Virtual Sensors

abstract:
  We calculate photometric redshifts from the Sloan Digital Sky Survey Main
Galaxy Sample, The Galaxy Evolution Explorer All Sky Survey, and The Two Micron
All Sky Survey using two new training-set methods. We utilize the broad-band
photometry from the three surveys alongside Sloan Digital Sky Survey measures
of photometric quality and galaxy morphology. Our first training-set method
draws from the theory of ensemble learning while the second employs Gaussian
process regression both of which allow for the estimation of redshift along
with a measure of uncertainty in the estimation. The Gaussian process models
the data very effectively with small training samples of approximately 1000
points or less. These two methods are compared to a well known Artificial
Neural Network training-set method and to simple linear and quadratic
regression. Our results show that robust photometric redshift errors as low as
0.02 RMS can regularly be obtained. We also demonstrate the need to provide
confidence bands on the error estimation made by both classes of models. Our
results indicate that variations due to the optimization procedure used for
almost all neural networks, combined with the variations due to the data
sample, can produce models with variations in accuracy that span an order of
magnitude. A key contribution of this paper is to quantify the variability in
the quality of results as a function of model and training sample. We show how
simply choosing the "best" model given a data set and model class can produce
misleading results.


title: Quantifying the Luminosity Evolution in Gamma-ray Bursts

abstract:
  We estimate the luminosity evolution and formation rate for over 900 GRBs by
using redshift and luminosity data calculated by Band, Norris, $&$ Bonnell
(2004) via the lag-luminosity correlation. By applying maximum likelihood
techniques, we are able to infer the true distribution of the parent GRB
population's luminosity function and density distributions in a way that
accounts for detector selection effects. We find that after accounting for data
truncation, there still exists a significant correlation between the average
luminosity and redshift, indicating that distant GRBs are on average more
luminous than nearby counterparts. This is consistent with previous studies
showing strong source evolution and also recent observations of under luminous
nearby GRBs. We find no evidence for beaming angle evolution in the current
sample of GRBs with known redshift, suggesting that this increase in luminosity
can not be due to an evolution of the collimation of gamma-ray emission. The
resulting luminosity function is well fit with a single power law of index
$L'^{-1.5}$, which is intermediate between the values predicted by the
power-law and Gaussian structured jet models. We also find that the GRB
comoving rate density rises steeply with a broad peak between $1<z<2$ followed
by a steady decline above $z> 3$. This rate density qualitatively matches the
current estimates of the cosmic star formation rate, favoring a short lived
massive star progenitor model, or a binary model with a short delay between the
formation of the compact object and the eventual merger.


title: Discovery of a 500 pc shell in the nucleus of Centaurus A

abstract:
  Spitzer Space Telescope mid-infrared images of the radio galaxy Centaurus A
reveal a shell-like, bipolar, structure 500 pc to the north and south of the
nucleus. This shell is seen in 5.8, 8.0 and 24 micron broad-band images. Such a
remarkable shell has not been previously detected in a radio galaxy and is the
first extragalactic nuclear shell detected at mid-infrared wavelengths. We
estimate that the shell is a few million years old and has a mass of order
million solar masses. A conservative estimate for the mechanical energy in the
wind driven bubble is 10^53 erg. The shell could have created by a small few
thousand solar mass nuclear burst of star formation. Alternatively, the
bolometric luminosity of the active nucleus is sufficiently large that it could
power the shell. Constraints on the shell's velocity are lacking. However, if
the shell is moving at 1000 km/s then the required mechanical energy would be
100 times larger.


title: RICE Limits on the Diffuse Ultra-High Energy Neutrino Flux

abstract:
  We present new limits on ultra-high energy neutrino fluxes above 100 PeV
based on data collected by the Radio Ice Cherenkov Experiment (RICE) at the
South Pole from 1999-2005. We discuss estimation of backgrounds, calibration
and data analysis algorithms (both on-line and off-line), procedures used for
the dedicated neutrino search, and refinements in our Monte Carlo (MC)
simulation, including recent in situ measurements of the complex ice dielectric
constant. An enlarged data set and a more detailed study of hadronic showers
results in a sensitivity improvement of more than one order of magnitude
compared to our previously published results. Examination of the full RICE data
set yields zero acceptable neutrino candidates, resulting in 95%
confidence-level model dependent limits on the flux
(E_\nu)^2(d\phi/dE_\nu)<10^{-6} GeV/(cm^2s~sr}) in the energy range 10^{17}<
E_\nu< 10^{20} eV. The new RICE results rule out the most intense flux model
projections at 95% confidence level.


title:
Time Delays for the Giant Quadruple Lensed Quasar SDSS J1004+4112:
  Prospects for Determining the Density Profile of the Lensing Cluster

abstract:
  We investigate the dependence of the time delays for the large-separation
gravitationally lensed quasar SDSS J1004+4112 on the inner mass profile of the
lensing cluster. Adopting the mass model whose innermost density profile is
parameterized as \rho \propto r^{-\alpha}, we derive a series of mass models
which can fit observational data and then compute the probability distribution
functions of time delays. We find that larger \alpha has longer time delays,
longer tails at the higher end of the probability distribution, and larger
model uncertainties. The ratios of time delays slightly depend on the slope
\alpha. Among others, time delays between images C and A (or B) have little
dependence on the inner slope, particularly when the time delays are short. The
dependence of time delays on \alpha is well fitted by a linear form, which
reflects well-known degeneracy between the mass profile and time delays. We
perform a Monte-Carlo simulation to illustrate how well the inner slope can be
constrained from measurements of time delays. We find that measurements of more
than one time delays result in reasonably tight constraints on the inner slope
(\sigma_{\alpha} \lesssim 0.25), while only one time delay cannot determine the
inner slope very well. Our result indicates that time delays indeed serve as a
powerful tool to determine the mass profile, despite the complexity of the
lensing cluster.


title:
An improved redshift indicator for Gamma-Ray Bursts, based on the prompt
  emission

abstract:
  We propose an improved version of the redshift indicator developed by Atteia
(2003), which gets rid of the dependence on the burst duration and provides
better estimates for high-redshift GRBs. We present the derivation and the
definition of this redshift indicator, then its calibration with 17 GRBs with
known redshifts detected by HETE-2 and 2 more detected by Konus-Wind. We also
provide an estimation of the redshift for 59 bursts, and we finally discuss the
redshift distribution of HETE-bursts and the possible other applications of
this redshift indicator.


title: Spectral analysis of extinguished sunlight

abstract:
  SAOZ (Systeme d'Analyse par Observation Zenitale) is a balloon born
experiment which determines the column density of several molecular species
from the visible spectrum of sunlight. We will use sequence of spectra
collected during a sunset to discuss atmospheric extinction, and the nature of
the radiation field in the atmosphere. The radiation field in the atmosphere
is, from daylight to sunset, and with a clear sky, dominated by light coming
from the direction of the sun. This light is composed of direct sunlight
(extinguished by the gas), and of sunlight forward-scattered by aerosols. As
the sun sets, aerosol scattering is first perceived towards the UV. It
progressively replaces direct sunlight over all of the spectrum. Our analysis
permits fixing the main parameters of each component of the radiation field at
any time. The fits we find for the extinction of sunlight in the atmosphere
must also apply to starlight. Thus, the present work can be used in astronomy
to correct ground-based spectral observations for extinction in the atmosphere.


title: Spectral analysis of red scattered sunlight at sunrise

abstract:
  We analyze and fit visible spectra of a red horizon at sunrise. The shape of
the spectra consist of a blue continuum followed by a red bump. The reddest
spectra are well fitted by the product of a spectrum of extinguished sunlight
(Rayleigh extinction + ozone absorption) and 1/lambda^4. The former is
essentially the radiation field in the outer atmosphere, at the scattering
volume location; the latter corresponds to Rayleigh scattering by the gas.
Moving to higher altitudes, a second component, corresponding to the spectrum
of a blue sky, must be added. The spectra we have obtained are similar to
spectra of red nebulae, suggesting there may be other explanations than an
emission process to the red color of some nebulae.


title: Inflation and accelerated expansion TeVeS cosmological solutions

abstract:
  We find exact exponentially expanding and contracting de Sitter solutions of
the spatially homogeneous TeVeS cosmological equations of motion in the vacuum
TeVeS model and a power law accelerated expanding solution in thepresence of an
additional ideal fluid with equation of state parameter $-5/3 < \omega < -1$. A
preliminary stability analysis shows that the expanding vacuum solution is
stable, while in the ideal fluid case stability depends on model parameter
values. These solutions might provide a basis for incorporating early-time
inflation or late-time accelerated expansion in TeVeS cosmology.


title: Excitation of g modes in Wolf-Rayet stars by a deep opacity bump

abstract:
  We examine the stability of l=1 and l=2 g modes in a pair of nitrogen-rich
Wolf-Rayet stellar models characterized by differing hydrogen abundances. We
find that modes with intermediate radial orders are destabilized by a kappa
mechanism operating on an opacity bump at an envelope temperature log T ~ 6.25.
This `deep opacity bump' is due primarily to L-shell bound-free transitions of
iron. Periods of the unstable modes span ~ 11-21 hr in the model containing
some hydrogen, and ~ 3-12 hr in the hydrogen-depleted model. Based on the
latter finding, we suggest that self-excited g modes may be the source of the
9.8 hr-periodic variation of WR 123 recently reported by Lefevre et al. (2005).


title:
Detectability of [CII] 158 micron emission from high-redshift galaxies:
  predictions for ALMA and SPICA

abstract:
  We discuss the detectability of high-redshift galaxies via [CII] 158 micron
line emission by coupling an analytic model with cosmological Smoothed Particle
Hydrodynamics (SPH) simulations that are based on the concordance Lambda cold
dark matter (CDM) model. Our analytic model describes a multiphase interstellar
medium irradiated by the far ultra-violet radiation from local star-forming
regions, and it calculates thermal and ionization equilibrium between cooling
and heating. The model allows us to predict the mass fraction of a cold neutral
medium (CNM) embedded in a warm neutral medium (WNM). Our cosmological SPH
simulations include a treatment of radiative cooling/heating, star formation,
and feedback effects from supernovae and galactic winds. Using our method, we
make predictions for the [CII] luminosity from high-redshift galaxies which can
be directly compared with upcoming observations by the Atacama Large Millimeter
Array (ALMA) and the Space Infrared Telescope for Cosmology and Astrophysics
(SPICA). We find that the number density of high-redshift galaxies detectable
by ALMA and SPICA via [CII] emission depends significantly on the amount of
neutral gas which is highly uncertain. Our calculations suggest that, in a CDM
universe, most [CII] sources at z=3 are faint objects with \Snu < 0.01 mJy.
Lyman-break galaxies (LBGs) brighter than R_AB=23.5 mag are expected to have
flux densities \Snu = 1-3 mJy depending on the strength of galactic wind
feedback. The recommended observing strategy for ALMA and SPICA is to aim at
very bright LBGs or star-forming DRG/BzK galaxies.


title: Mechanical Model for Relativistic Blast Waves and Stratified Fireballs

abstract:
  We propose a simple mechanical model for relativistic explosions with both
forward and reverse shocks, which allows one to do fast calculations of GRB
afterglow. The blast wave in the model is governed by pressures P_F and P_R at
the forward and reverse shocks. We show that the simplest assumption P_F=P_R is
in general inconsistent with energy conservation law. The model is applied to
GRBs with non-uniform ejecta. Such "stratified fireballs" are likely to emerge
with a monotonic velocity profile after an internal-shock stage. We calculate
the early afterglow emission expected from stratified fireballs.


title: Neutrino-cooled Accretion Disks around Spinning Black Holes

abstract:
  We calculate the structure of accretion disk around a spinning black hole for
accretion rates 0.01 - 10 M_sun/s. The model is fully relativistic and treats
accurately the disk microphysics including neutrino emissivity, opacity,
electron degeneracy, and nuclear composition. We find that the accretion flow
always regulates itself to a mildly degenerate state with the proton-to-nucleon
ratio Y_e ~ 0.1 and becomes very neutron-rich. The disk has a well defined
"ignition" radius where neutrino flux raises dramatically, cooling becomes
efficient, and Y_e suddenly drops. We also calculate other characteristic radii
of the disk, including the neutrino-opaque and neutrino-trapping radii, and
show their dependence on the accretion rate. Accretion disks around
fast-rotating black holes produce intense neutrino fluxes which may deposit
enough energy above the disk to generate a GRB jet.


title: Cosmic ray recipes

abstract:
  Cosmic rays represent one of the most fascinating research themes in modern
astronomy and physics. After almost a century since their discovery, a huge
amount of scientific literature has been written on this topic and it is not
always easy to extract from it the necessary information for somebody who
approaches the subject for the first time. This has been the main motivation
for preparing this article, which is a concise and self-contained review for
whoever is interested in studying cosmic rays. The priority has been given here
to well established facts, which are not at risk to get obsolete in a few years
due to the fast progress of the research in this field. Also many data are
presented, which are useful to characterize the doses of ionizing radiation
delivered to organisms living on the Earth due to cosmic rays. The technical
terms which are often encountered in the scientific literature are explained in
a separate appendix.


title: An empirical calibration of the mixing-length parameter alpha

abstract:
  We present an empirical calibration of the Mixing-Length free parameter
${\alpha}$ based on a homogeneous Infrared database of 28 Galactic globular
clusters spanning a wide metallicity range (-2.15$<$[Fe/H]$<$-0.2). Empirical
estimates of the red giant effective temperatures have been obtained from
infrared colors. Suitable relations linking these temperatures to the cluster
metallicity have been obtained and compared to theoretical predictions. An
appropriate set of models for the Sun and Population II giants have been
computed by using both the standard solar metallicity $[Z/X]_{\odot}=0.0275$
and the most recently proposed value $[Z/X]_{\odot}=$0.0177. We find that when
the standard solar metallicity is adopted, a unique value of $\alpha$=2.17 can
be used to reproduce both the solar radius and the population II red giant
temperature. Conversely, when the new solar metallicity is adopted, two
different values of $\alpha$ are required: $\alpha=1.86$ to fit the solar
radius and $\alpha \approx2.0$ to fit the red giant temperatures. However, it
must be noted that, regardless the adopted solar reference, the $\alpha$
parameter does not show any significant dependence on metallicity.


title: Self-consistent response of a galactic disc to vertical perturbations

abstract:
  We study the self-consistent, linear response of a galactic disc to vertical
perturbations as induced say by a tidal interaction. We calculate the
self-gravitational potential corresponding to a non-axisymmetric,
self-consistent density response of the disc using the Green's function method.
The response potential is shown to oppose the perturbation potential because
the self-gravity of the disc resists the imposed potential, and this resistence
is stronger in the inner parts of a galactic disc. For the m=1 azimuthal
wavenumber, the disc response opposes the imposed perturbation upto a radius
that spans a range of 4-6 disc scale-lengths, so that the disc shows a net warp
only beyond this region. This physically explains the well-known but so far
unexplained observation (Briggs 1990) that warps typically set in beyond this
range of radii. We show that the inclusion of a dark matter halo in the
calculation only marginally changes (by ~ 10 %) the radius for the onset of
warps. For perturbations with higher azimuthal wavenumbers, the net signature
of the vertical perturbations can only be seen at larger radii - for example
beyond 7 exponential disc scale-lengths for m=10. Also, for high m cases, the
magnitude of the negative disc response due to the disc self-gravity is much
smaller. This is shown to result in corrugations of the mid-plane density,
which explains the puzzling scalloping with m=10 detected in HI in the
outermost regions ~ 30 kpc in the Galaxy by Kulkarni et al. (1982).


title:
Resonant relaxation near a massive black hole: the stellar distribution
  and gravitational wave sources

abstract:
  Resonant relaxation (RR) of orbital angular momenta occurs near massive black
holes (MBHs) where the stellar orbits are nearly Keplerian and so do not
precess significantly. The resulting coherent torques efficiently change the
magnitude of the angular momenta and rotate the orbital inclination in all
directions. As a result, many of the tightly bound stars very near the MBH are
rapidly destroyed by falling into the MBH on low-angular momentum orbits, while
the orbits of the remaining stars are efficiently randomized. We solve
numerically the Fokker-Planck equation in energy for the steady state
distribution of a single mass population with a RR sink term. We find that the
steady state current of stars, which sustains the accelerated drainage close to
the MBH, can be up to ~10 times larger than that due to non-coherent 2-body
relaxation alone. RR mostly affects tightly bound stars, and so it increases
only moderately the total tidal disruption rate, which is dominated by stars
originating from less bound orbits farther away. We show that the event rate of
gravitational wave (GW) emission from inspiraling stars, originating much
closer to the MBH, is dominated by RR dynamics. The GW event rate depends on
the uncertain efficiency of RR. The efficiency indicated by the few available
simulations implies rates ~10 times higher than those predicted by 2-body
relaxation, which would improve the prospects of detecting such events by
future GW detectors, such as LISA. However, a higher, but still plausible RR
efficiency can lead to the drainage of all tightly bound stars and strong
suppression of GW events from inspiraling stars. We apply our results to the
Galactic MBH, and show that the observed dynamical properties of stars there
are consistent with RR.


title: Optical Properties of Radio-selected Narrow Line Seyfert 1 Galaxies

abstract:
  We present results from the analysis of the optical spectra of 47
radio-selected narrow-line Seyfert 1 galaxies (NLS1s). These objects are a
subset of the First Bright Quasar Survey (FBQS) and were initially detected at
20 cm (flux density limit ~1 mJy) in the VLA FIRST Survey. We run Spearman rank
correlation tests on several sets of parameters and conclude that, except for
their radio properties, radio-selected NLS1 galaxies do not exhibit significant
differences from traditional NLS1 galaxies. Our results are also in agreement
with previous studies suggesting that NLS1 galaxies have small black hole
masses that are accreting very close to the Eddington rate. We have found 16
new radio-loud NLS1 galaxies, which increases the number of known radio-loud
NLS1 galaxies by a factor of ~5.


title: Dark Energy Constraints from Baryon Acoustic Oscillations

abstract:
  Baryon acoustic oscillations (BAO) in the galaxy power spectrum allows us to
extract the scale of the comoving sound horizon at recombination, a
cosmological standard ruler accurately determined by the cosmic microwave
background anisotropy data. We examine various issues important in the use of
BAO to probe dark energy. We find that assuming a flat universe, and priors on
Omega_m, Omega_m h^2, and Omega_b h^2 as expected from the Planck mission, the
constraints on dark energy parameters (w_0,w') scale much less steeply with
survey area than (area)^{-1/2} for a given redshift range. The constraints on
the dark energy density rho_X(z), however, do scale roughly with (area)^{-1/2}
due to the strong correlation between H(z) and Omega_m (which reduces the
effect of priors on Omega_m). Dark energy constraints from BAO are very
sensitive to the assumed linear scale of matter clustering and the redshift
accuracy of the survey. For a BAO survey with 0.5<= z <= 2, sigma(R)=0.4
(corresponding to k_{max}(z=0)=0.086 h Mpc^{-1}), and sigma_z/(1+z)=0.001,
(sigma_{w_0},sigma_{w'})=(0.115, 0.183) and (0.069, 0.104) for survey areas of
1000 (deg)^2 and 10000 (deg)^2 respectively. We find that it is critical to
minimize the bias in the scale estimates in order to derive reliable dark
energy constraints. For a 1000 (10000) square degree BAO survey, a 1-sigma bias
in ln H(z) leads to a 2-sigma (3-sigma) bias in w'. The bias in w' due to the
same scale bias from ln D_A(z) is slightly smaller and opposite in sign. The
results from this paper will be useful in assessing different proposed BAO
surveys and guiding the design of optimal dark energy detection strategies.


title: Hydrodynamic simulations of He-shell flash convection

abstract:
  We present the first hydrodynamic, multi-dimensional simulations of He-shell
flash convection. Specifically, we investigate the properties of shell
convection at a time immediately before the He- luminosity peak during the 15th
thermal pulse of a stellar evolution track with initially two solar masses and
metallicity Z=0.01. This choice is a representative example of a low-mass
asymptotic giant branch thermal pulse. We construct the initial vertical
stratification with a set of polytropes to resemble the stellar evolution
structure. Convection is driven by a constant volume heating in a thin layer at
the bottom of the unstable layer. We calculate a grid of 2D simulations with
different resolutions and heating rates. Our set of simulations includes one
low-resolution 3D run. The computational domain includes 11.4 pressure scale
heights. He-shell flash convection is dominated by large convective cells that
are centered in the lower half of the convection zone. Convective rolls have an
almost circular appearance because focusing mechanisms exist in the form of the
density stratification for downdrafts and the heating of localized eddies that
generate upflows. Nevertheless, downdrafts appear to be somewhat more focused.
The He-shell flash convection generates a rich spectrum of gravity waves in
both stable layers above and beneath the convective shell. The magnitude of the
convective velocities from our 1D mixing-length theory model and the
rms-averaged vertical velocities from the hydrodynamic model are consistent
within a factor of a few. However, the velocity profile in the hydrodynamic
simulation is more asymmetric, and decays exponentially inside the convection
zone. [abbreviated]


title:
The near-infrared luminosity function of cluster galaxies beyond
  redshift one

abstract:
  We determined the K band luminosity function (LF) of cluster galaxies at
redshift z~1.2, using near-infrared images of three X-ray luminous clusters at
z=1.11,1.24,1.27. The composite LF was derived down to M*+4, by means of
statistical background subtraction, and is well described by a Schechter
function with K*=20.5 AB mag and alpha=-1.
  From the K band composite LF we derived the stellar mass function of cluster
galaxies. Using available X-ray mass profiles we determined the M/L ratios of
these three clusters, which tend to be lower than those measured in the local
universe.
  With these data, no significant difference can be seen between the shapes of
the cluster galaxies LF and the LF of field galaxies at similar redshift.
  We also found no significant evolution out to z ~1.2 in the bright (<M*+4)
part of the cluster galaxies LF probed in this study, apart from a brightening
of ~1.3 mag of the characteristic magnitude of the high redshift LF. We
confirm, and extend to higher redshift, the result from previous work that the
redshift evolution of the characteristic magnitude M* is consistent with
passive evolution of a stellar population formed at z>2.
  The results obtained in this work support and extend previous findings that
most of the stars in bright galaxies were formed at high redshift, and that
K-bright (M>10^11 Msun) galaxies were already in place at z ~ 1.2, at least in
the central regions of X-ray luminous clusters. Together with recent results on
the field galaxies stellar mass function, this implies that most of the stellar
mass is already assembled in massive galaxies by z ~ 1, both in low and high
density environments.


title: Encounter-Triggered Disc Mass Loss in the ONC

abstract:
  The relevance of encounters on the destruction of protoplanetary discs in the
Orion Nebula Cluster (ONC) is investigated by combining two different types of
numerical simulation. First, star-cluster simulations are performed to model
the stellar dynamics of the ONC, the results of which are used to investigate
the frequency of encounters, the mass ratio and separation of the stars
involved, and the eccentricity of the encounter orbits. The results show that
interactions that could influence the star-surrounding disc are more frequent
than previously assumed in the core of the ONC, the so-called Trapezium
cluster. Second, a parameter study of star-disc encounters is performed to
determine the upper limits of the mass loss of the discs in encounters. For
simulation times of $\sim$ 1-2 Myr (the likely age of the ONC) the results show
that gravitational interaction might account for a significant disc mass loss
in dense clusters. Disc destruction is dominated by encounters with high-mass
stars, especially in the Trapezium cluster, where the fraction of discs
destroyed due to stellar encounters can reach 10-15%. These estimates are in
accord with observations of (Lada et al. 2000) who determined a stellar disc
fraction of 80-85%. Thus, it is shown that in the ONC - a typical star-forming
region - stellar encounters do have a significant effect on the mass of
protoplanetary discs and thus affect the formation of planetary systems.


title: The Butcher--Oemler effect at z~0.35: a change in perspective

abstract:
  The present paper focuses on the much debated Butcher-Oemler effect: the
increase with redshift of the fraction of blue galaxies in clusters.
Considering a representative cluster sample made of seven group/clusters at
z~0.35, we have measured the blue fraction from the cluster core to the cluster
outskirts and the field mainly using wide field CTIO images. This sample
represents a random selection of a volume complete x-ray selected cluster
sample, selected so that there is no physical connection with the studied
quantity (blue fraction), to minimize observational biases. In order to
statistically assess the significance of the Butcher-Oemler effect, we
introduce the tools of Bayesian inference. Furthermore, we modified the blue
fraction definition in order to take into account the reduced age of the
universe at higher redshifts, because we should no longer attempt to reject an
unphysical universe in which the age of the Universe does depend on redshift,
whereas the age of its content does not. We measured the blue fraction from the
cluster center to the field and we find that the cluster affects the properties
of the galaxies up to two virial radii at z~0.35. Data suggest that during the
last 3 Gyrs no evolution of the blue fraction, from the cluster core to the
field value, is seen beyond the one needed to account for the varying age with
redshift of the Universe and of its content. The agreement of the radial
profiles of the blue fraction at z=0 and z~0.35 implies that the pattern infall
did not change over the last 3 Gyr, or, at least, its variation has no
observational effect on the studied quantity.


title: The Cosmological Parameters 2006

abstract:
  This is a review article for The Review of Particle Physics 2006 (aka the
Particle Data Book). It forms a compact review of knowledge of the cosmological
parameters as at May 2006. Topics included are Parametrizing the Universe;
Extensions to the standard model; Probes; Bringing observations together;
Outlook for the future.


title:
Resolving the compact dusty discs around binary post-AGB stars using
  N-band interferometry

abstract:
  We present the first mid-IR long baseline interferometric observations of the
circumstellar matter around binary post-AGB stars. Two objects, SX Cen and HD
52961, were observed using the VLTI/MIDI instrument during Science
Demonstration Time. Both objects are known binaries for which a stable
circumbinary disc is proposed to explain the SED characteristics. This is
corroborated by our N-band spectrum showing a crystallinity fraction of more
than 50 % for both objects, pointing to a stable environment where dust
processing can occur. Surprisingly, the dust surrounding SX Cen is not resolved
in the interferometric observations providing an upper limit of 11 mas (or 18
AU at the distance of this object) on the diameter of the dust emission. This
confirms the very compact nature of its circumstellar environment. The dust
emission around HD 52961 originates from a very small but resolved region,
estimated to be ~ 35 mas at 8 micron and ~ 55 mas at 13 micron. These results
confirm the disc interpretation of the SED of both stars. In HD 52961, the dust
is not homogeneous in its chemical composition: the crystallinity is clearly
concentrated in the hotter inner region. Whether this is a result of the
formation process of the disc, or due to annealing during the long storage time
in the disc is not clear.


title: A deep wide-field optical survey in the young open cluster Collinder 359

abstract:
  We present the first deep, optical, wide-field imaging survey of the young
open cluster Collinder 359, complemented by near-infrared follow-up
observations. This study is part of a large programme aimed at examining the
dependence of the mass function on environment and time. We have surveyed 1.6
square degrees in the cluster, in the I and z filters, with the CFH12K camera
on the Canada-France-Hawaii 3.6-m telescope down to completeness and detection
limits in both filters of 22.0 and 24.0 mag, respectively. Based on their
location in the optical (I-z,I) colour-magnitude diagram, we have extracted new
cluster member candidates in Collinder 359 spanning 1.3-0.03 Msun assuming an
age of 60 Myr and a distance of 450 pc for the cluster. We have used the 2MASS
database as well as our own near-infrared photometry to examine the membership
status of the optically-selected cluster candidates. Comparison of the location
of the most massive members in Collinder 359 in a (B-V,V) diagram with
theoretical isochrones suggests that Collinder 359 is older than Alpha Per but
younger than the Pleiades. We discuss the possible relationship between
Collinder 359 and IC 4665 as both clusters harbour similar parameters,
including proper motion, distance, and age.


title: Is space really expanding? A counterexample

abstract:
  In all Friedman models, the cosmological redshift is widely interpreted as a
consequence of the general-relativistic phenomenon of EXPANSION OF SPACE. Other
commonly believed consequences of this phenomenon are superluminal recession
velocities of distant galaxies and the distance to the particle horizon greater
than c*t (where t is the age of the Universe), in apparent conflict with
special relativity. Here, we study a particular Friedman model: empty universe.
This model exhibits both cosmological redshift, superluminal velocities and
infinite distance to the horizon. However, we show that the cosmological
redshift is there simply a relativistic Doppler shift. Moreover, apparently
superluminal velocities and `acausal' distance to the horizon are in fact a
direct consequence of special-relativistic phenomenon of time dilation, as well
as of the adopted definition of distance in cosmology. There is no conflict
with special relativity, whatsoever. In particular, INERTIAL recession
velocities are subluminal. Since in the real Universe, sufficiently distant
galaxies recede with relativistic velocities, these special-relativistic
effects must be at least partly responsible for the cosmological redshift and
the aforementioned `superluminalities', commonly attributed to the expansion of
space. Let us finish with a question resembling a Buddhism-Zen `koan': in an
empty universe, what is expanding?


title: The role of kink instability in Poynting-flux dominated jets

abstract:
  The role of kink instability in magnetically driven jets is explored through
numerical one-dimensional steady relativistic MHD calculations. The instability
is shown to have enough time to grow and influence the dynamics of
Poynting-flux dominated jets. In the case of AGN jets, the flow becomes kinetic
flux dominated at distances larger than ~1000 r_g because of the rapid
dissipation of Poynting flux. When applied to GRB outflows, the model predicts
more gradual Poynting dissipation and moderately magnetized flow at distances
of ~10^{16} cm where the deceleration of the ejecta due to its interaction with
the external medium is expected. The energy released by the instability can
power the compact ``blazar zone'' emission and the prompt emission of GRB
outflows with high radiative efficiencies.


title: X-ray flare in XRF 050406: evidence for prolonged engine activity

abstract:
  We present observations of XRF 050406, the first burst detected by Swift
showing a flare in its X-ray light curve. During this flare, which peaks at
t_peak ~210s after the BAT trigger, a flux variation of (delta F)/F~6 in a very
short time (delta t)/t_peak<<1 was observed. Its measured fluence in the 0.2-10
keV band was ~1.4x10^-8 erg cm^-2, which corresponds to 1-15% of the prompt
fluence. We present indications of spectral variations during the flare. We
argue that the producing mechanism is late internal shocks, which implies that
the central engine is still active at 210s, though with a reduced power with
respect to the prompt emission. The X-ray light curve flattens to a very
shallow slope with decay index of ~0.5 after ~4400s, which also supports
continued central engine activity at late times. This burst is classified as an
X-ray flash, with a relatively low fluence (~10^-7 erg cm^-2 in the 15-350 keV
band, E_iso~10^51 erg), a soft spectrum (photon index 2.65), no significant
flux above ~50 keV and a peak energy E_p<15 keV. XRF 050406 is one of the first
examples of a well-studied X-ray light curve of an XRF. We show that the main
afterglow characteristics are qualitatively similar to those of normal GRBs. In
particular, X-ray flares superimposed on a power-law light curve have now been
seen in both XRFs and GRBs. This indicates that a similar mechanism may be at
work for both kinds of events.


title:
Interstellar Extinction Law in the J, H, and Ks Bands toward the
  Galactic Center

abstract:
  We have determined the ratios of total to selective extinction in the
near-infrared bands (J, H, Ks) toward the Galactic center from the observations
of the region |l| < 2.0deg and 0.5deg < |b| < 1.0deg with the IRSF telescope
and the SIRIUS camera. Using the positions of red clump stars in
color-magnitude diagrams as a tracer of the extinction and reddening, we
determine the average of the ratios of total to selective extinction to be
A(Ks)/E(H-Ks) = 1.44+-0.01, A(Ks)/E(J-Ks) = 0.494+-0.006, and A(H)/E(J-H) =
1.42+-0.02, which are significantly smaller than those obtained in previous
studies. From these ratios, we estimate that A(J) : A(H) : A(Ks) = 1 :
0.573+-0.009 : 0.331+-0.004 and E(J-H)/E(H-Ks) = 1.72+-0.04, and we find that
the power law A(lambda) \propto lambda^{-1.99+-0.02} is a good approximation
over these wavelengths. Moreover, we find a small variation in A(Ks)/E(H-Ks)
across our survey. This suggests that the infrared extinction law changes from
one line of sight to another, and the so-called ``universality'' does not
necessarily hold in the infrared wavelengths.


title: The Chandra view of the 3C/FRI sample of low luminosity radio-galaxies

abstract:
  We present results from Chandra observations of the 3C/FRI sample of low
luminosity radio-galaxies. We detected a power-law nuclear component in 12
objects out of the 18 with available data. In 4 galaxies we detected nuclear
X-ray absorption at a level of about N_H= (0.2-6)e22 cm-2. X-ray absorbed
sources are associated with the presence of highly inclined dusty disks (or
dust filaments projected onto the nuclei) seen in the HST images. This suggests
the existence of a flattened X-ray absorber, but of much lower optical depth
than in classical obscuring tori. We thus have an un-obstructed view toward
most FR~I nuclei while absorption plays only a marginal role in the remaining
objects. Three pieces of evidence support an interpretation for a jet origin
for the X-ray cores: i) the presence of strong correlations between the nuclear
luminosities in the radio, optical and X-ray bands, extending over 4 orders of
magnitude and with a much smaller dispersion (about 0.3 dex) when compared to
similar trends found for other classes of AGNs, pointing to a common origin for
the emission in the three bands; ii) the close similarity of the broad-band
spectral indices with the sub-class of BL Lac objects sharing the same range of
extended radio-luminosity, in accord with the FRI/BL Lacs unified model; iii)
the presence of a common luminosity evolution of spectral indices in both FRI
and BL Lacs. The low luminosities of the X-ray nuclei, regardless of their
origin, strengthens the interpretation of low efficiency accretion in low
luminosity radio-galaxies.


title:
A radial velocity survey of low Galactic latitude structures: III. The
  Monoceros Ring in front of the Carina and Andromeda galaxies

abstract:
  As part of our radial velocity survey of low Galactic latitude structures
that surround the Galactic disc, we report the detection of the so called
Monoceros Ring in the foreground of the Carina dwarf galaxy at Galactic
coordinates (l,b)=(260,-22) based on VLT/FLAMES observations of the dwarf
galaxy. At this location, 20 degrees in longitude greater than previous
detections, the Ring has a mean radial velocity of 145+/-5 km/s and a velocity
dispersion of only 17+/-5 km/s. Based on Keck/DEIMOS observations, we also
determine that the Ring has a mean radial velocity of -75+/-4 km/s in the
foreground of the Andromeda galaxy at (l,b)\sim(122,-22), along with a velocity
dispersion of 26+/-3 km/s. These two kinematic detections are both highly
compatible with known characteristics of the structure and, along with previous
detections provide radial velocity values of the Ring over the 120<l<260 range.
This should add strong constraints on numerical models of the accretion of the
dwarf galaxy that is believed to be the progenitor of the Ring.


title: Deep X-ray survey of the young open cluster NGC 2516 with XMM-Newton

abstract:
  We report on a deep X-ray survey of the young (~ 140 Myr), rich open cluster
NGC 2516 obtained with the EPIC camera on board the XMM-Newton satellite. By
combining data from six observations, a high sensitivity, greater than a factor
5 with respect to recent Chandra observations, has been achieved. We detected
431 X-ray sources and 234 of them have as optical counterparts cluster stars
spanning the entire NGC 2516 Main Sequence. The X-ray luminosities of cluster
stars span the range log Lx (erg/s) = 28.4 - 30.8. The representative
temperatures span the 0.3 - 0.6 keV (3.5 - 8 MK) range for the cool component
and 1.0 - 2.0 keV (12 -- 23 MK) for the hot one; similar values are found in
other young open clusters like the Pleiades, IC 2391, and Blanco 1. While no
significant differences are found in X-ray spectra, NGC 2516 solar type stars
are definitely less luminous in X-rays than the nearly coeval Pleiades. The
comparison with a previous ROSAT survey evidence the lack of variability
amplitudes larger than a factor 2 in solar type stars in a ~11 yr time scale of
the cluster and thus activity cycles like in the Sun are probably absent or
different by period and amplitude in young stars.


title: New Planetary Nebulae in the Galactic Bulge region with l>0deg - II

abstract:
  The presentation of new results from an [O III] 5007 A survey in a search for
planetary nebulae (PNe) in the galactic bulge is continued. A total of 60
objects, including 19 new PNe, have been detected in the remaining 34 per cent
of the survey area, while 41 objects are already known. Deep Halpha+[N II] CCD
images as well as low resolution spectra have been acquired for these objects.
Their spectral signatures suggest that the detected emission originates from
photoionized nebulae. In addition, absolute line fluxes have been measured and
the electron densities are given. Accurate optical positions and optical
diameters are also determined.


title:
The Luminosity, Colour and Morphology dependence of galaxy filaments in
  the Sloan Digital Sky Survey Data Release Four

abstract:
  We have tested for luminosity, colour and morphology dependence of the degree
of filamentarity in seven nearly two dimensional strips from the Sloan Digital
Sky Survey Data Release Four (SDSS DR4). The analysis is carried out at various
levels of coarse graining allowing us to address different length-scales. We
find that the brighter galaxies have a less filamentary distribution than the
fainter ones at all levels of coarse graining. The distribution of red galaxies
and ellipticals shows a higher degree of filamentarity compared to blue
galaxies and spirals respectively at low levels of coarse graining. The
behaviour is reversed at higher levels of coarse graining. We propose a picture
where the ellipticals are densely distributed in the vicinity of the nodes
where the filaments intersect while the spirals are sparsely distributed along
the entire extent of the filaments. Our findings indicate that the regions with
an excess of ellipticals are larger than galaxy clusters, protruding into the
filaments. We have also compared the predictions of a semi-analytic model of
galaxy formation (the Millennium Run galaxy catalogue) against our results for
the SDSS. We find the two to be in agreement for the $M^{*}$ galaxies and for
the red galaxies, while the model fails to correctly predict the filamentarity
of the brighter galaxies and the blue galaxies.


title: The Ultra Luminous X-ray sources in the High Velocity System of NGC 1275

abstract:
  We report the results of a study of X-ray point sources coincident with the
High Velocity System (HVS) projected in front of NGC 1275. A very deep X-ray
image of the core of the Perseus cluster made with the Chandra Observatory has
been used. We find a population of Ultra-Luminous X-ray sources (ULX; 7 sources
with LX [0.5-7 keV] > 7x10^39 erg/s). As with the ULX populations in the
Antennae and Cartwheel galaxies, those in the HVS are associated with a region
of very active star formation. Several sources have possible optical
counterparts found on HST images, although the X-ray brightest one does not.
Absorbed power-law models fit the X-ray spectra, with most having a photon
index between 2 and 3.


title: Optical and Infrared Non-detection of the z=10 Galaxy Behind Abell 1835

abstract:
  Gravitational lensing by massive galaxy clusters is a powerful tool for the
discovery and study of high redshift galaxies, including those at z>=6 likely
responsible for cosmic re-ionization. Pello et al. recently used this technique
to discover a candidate gravitationally magnified galaxy at z=10 behind the
massive cluster lens Abell 1835 (z=0.25). We present new Keck (LRIS) and
Spitzer Space Telescope (IRAC) observations of the z=10 candidate (hereafter
#1916) together with a re-analysis of archival optical and near-infrared
imaging from the Hubble Space Telescope and VLT respectively. Our analysis
therefore extends from the atmospheric cut-off at lambda_obs=0.35um out to
lambda_obs=5um with Spitzer/IRAC. The z=10 galaxy is not detected in any of
these data, including an independent reduction of Pello et al.'s discovery H-
and K-band imaging. We conclude that there is no statistically reliable
evidence for the existence of #1916. We also assess the implications of our
results for ground-based near-infrared searches for gravitationally magnified
galaxies at z>~7. The broad conclusion is that such experiments remain
feasible, assuming that space-based optical and mid-infrared imaging are
available to break the degeneracy with low redshift interlopers (e.g. z~2-3)
when fitting spectral templates to the photometric data.


title: Swift-UVOT Observations of the X-Ray Flash 050406

abstract:
  We present Swift-UVOT data on the optical afterglow of the X-ray flash of
2005 April 6 (XRF 050406) from 88s to \sim 10^5s after the initial prompt
gamma-ray emission. Our observations in the V, B and U bands are the earliest
that have been taken of an XRF optical counterpart. Combining the early -time
optical temporal and spectral properties with \gamma- and simultaneous X-ray
data taken with the BAT and XRT telescopes on-board Swift, we are able to
constrain possible origins of the XRF. The prompt emission had a FRED profile
(fast-rise, exponential decay) with a duration of T_90 = 5.7\pm 0.2s, putting
it at the short end of the long-burst duration distribution. The absence of
photoelectric absorption red-ward of 4000 \AA in the UV/optical spectrum
provides a firm upper limit of z\leq 3.1 on the redshift, thus excluding a high
redshift as the sole reason for the soft spectrum. The optical light curve is
consistent with a power-law decay with slope alpha = -0.75\pm 0.26
(F_{\nu}\propto t^{\alpha}), and a maximum occurring in the first 200s after
the initial gamma-ray emission. The softness of the prompt emission is well
described by an off-axis structured jet model, which is able to account for the
early peak flux and shallow decay observed in the optical and X-ray bands.


title:
A 3D radiative transfer framework: I. non-local operator splitting and
  continuum scattering problems

abstract:
  We describe a highly flexible framework to solve 3D radiation transfer
problems in scattering dominated environments based on a long characteristics
piece-wise parabolic formal solution and an operator splitting method. We find
that the linear systems are efficiently solved with iterative solvers such as
Gauss-Seidel and Jordan techniques. We use a sphere-in-a-box test model to
compare the 3D results to 1D solutions in order to assess the accuracy of the
method. We have implemented the method for static media, however, it can be
used to solve problems in the Eulerian-frame for media with low velocity
fields.


title:
The ECLAIRs micro-satellite mission for gamma-ray burst multi-wavelength
  observations

abstract:
  Gamma-ray bursts (GRB), at least those with a duration longer than a few
seconds are the most energetic events in the Universe and occur at cosmological
distances. The ECLAIRs micro-satellite, to be launched in 2009, will provide
multi-wavelength observations of GRB, to study their astrophysics and to use
them as cosmological probes. Furthermore in 2009 ECLAIRs is expected to be the
only space borne instrument capable of providing a GRB trigger in near
real-time with sufficient localization accuracy for GRB follow-up observations
with the powerful ground based spectroscopic telescopes available by then. A
"Phase A study" of the ECLAIRs project has recently been launched by the French
Space Agency CNES, aiming at a detailed mission design and selection for flight
in 2006. The ECLAIRs mission is based on a CNES micro-satellite of the
"Myriade" family and dedicated ground-based optical telescopes. The satellite
payload combines a 2 sr field-of-view coded aperture mask gamma-camera using
6400 CdTe pixels for GRB detection and localization with 10 arcmin precision in
the 4 to 50 keV energy band, together with a soft X-ray camera for onboard
position refinement to 1 arcmin. The ground-based optical robotic telescopes
will detect the GRB prompt/early afterglow emission and localize the event to
arcsec accuracy, for spectroscopic follow-up observations.


title: The true redshift distribution of Pre-SWIFT gamma-ray bursts

abstract:
  SWIFT bursts appear to be more distant than previous bursts. We present the
Boer & Gendre relation that link redshift and afterglow luminosities. Taking
advantage of the XMM-Newton, Chandra and BeppoSAX catalogs, and using this
relation, we have investigated the redshift distribution of GRBs. We find that
XMM burst sources with unknown redshift appear to be more distant than those
with a known redshift. We propose that this effect may be due to a selection
effect of pre-SWIFT optical observations.


title: Possibility of a photometric detection of "exomoons"

abstract:
  We examined which exo-systems contain moons that may be detected in transit.
We numerically modeled transit light curves of Earth-like and giant planets
that cointain moons with 0.005--0.4 Earth-mass. The orbital parameters were
randomly selected, but the entire system fulfilled Hill-stability. We conclude
that the timing effect is caused by two scenarios: the motion of the planet and
the moon around the barycenter. Which one dominates depends on the parameters
of the system. Already planned missions (Kepler, COROT) may be able to detect
the moon in transiting extrasolar Earth-Moon-like systems with a 20%
probability. From our sample of 500 free-designed systems, 8 could be detected
with the photometric accuracy of 0.1 mmag and a 1 minute sampling, and one
contains a stony planet. With ten times better accuracy, 51 detections are
expected. All such systems orbit far from the central star, with the orbital
periods at least 200 and 10 days for the planet and the moon, while they
contain K- and M-dwarf stars. Finally we estimate that a few number of real
detections can be expected by the end of the COROT and the Kepler missions.


title:
The dynamical state and blue straggler population of the globular
  cluster NGC 6266 (M62)

abstract:
  We have used a proper combination of multiband high-resolution {\it
HST-WFPC2} and wide-field ground based observations to image the galactic
globular cluster NGC 6266 (M62). The extensive photometric data set allows us
to determine the center of gravity and to construct the most extended radial
profile ever published for this cluster including, for the first time, detailed
star counts in the very inner region. The star density profile is well
reproduced by a standard King model with an extended core ($\sim 19''$) and a
modest value of the concentration parameter ($c=1.5$), indicating that the
cluster has not-yet experienced core collapse.
  The millisecond pulsar population (whose members are all in binary systems)
and the X-ray emitting population (more than 50 sources within the cluster half
mass radius) suggest that NGC 6266 is in a dynamical phase particularly active
in generating binaries through dynamical encounters. UV observations of the
central region have been used to probe the population of blue straggler stars,
whose origin might be also affected by dynamical interactions. The comparison
with other globular clusters observed with a similar strategy shows that the
blue straggler content in NGC 6266 is relatively low, suggesting that the
formation channel that produces binary systems hosting neutron stars or white
dwarfs is not effective in significantly increasing the blue straggler
population. Moreover, an anticorrelation between millisecond pulsar content and
blue straggler specific frequency in globular cluster seems emerging with
increasing evidence.


title: The Complete Spectral Catalog of Bright BATSE Gamma-Ray Bursts

abstract:
  We present a systematic spectral analysis of 350 bright GRBs observed with
BATSE, with high spectral and temporal resolution. Our sample was selected from
the complete set of 2704 BATSE GRBs, and included 17 short GRBs. To obtain
well-constrained spectral parameters, four different photon models were fitted
and the spectral parameters that best represent each spectrum were
statistically determined. A thorough analysis was performed on 350
time-integrated and 8459 time-resolved burst spectra. Using the results, we
compared time-integrated and time-resolved spectral parameters, and also
studied correlations among the parameters and their evolution within each
burst. The resulting catalog is the most comprehensive study of spectral
properties of GRB prompt emission to date, and provides constraints with
exceptional statistics on particle acceleration and emission mechanisms in
GRBs.


title:
Searches for diffuse X-ray emission around millisecond pulsars: An X-ray
  nebula associated with PSR J2124-3358

abstract:
  We report on diffuse X-ray emission associated with the nearby solitary
millisecond pulsar PSR J2124-3358 detected with XMM-Newton and Chandra. The
emission extends from the pulsar to the northwest by ~0.5 arcmin. The spectrum
of the nebular emission can be modeled with a power-law of photon index
$2.2\pm0.4$, in line with the emission originating from accelerated particles
in the post shock flow. For PSR J0437-4715, PSR J0030+0451 and PSR J1024-0719,
which all have spin parameters comparable to that of PSR J2124-3358, no diffuse
emission is detected down to a 3-sigma limiting flux of $4-7\times10^{-15}$
ergs s$^{-1}$ cm$^{-2}$.


title: Short Gamma-Ray Bursts with Extended Emission

abstract:
  The recent association of several short gamma-ray bursts (GRBs) with early
type galaxies with low star formation rate demonstrates that short bursts arise
from a different progenitor mechanism than long bursts. However, since the
duration distributions of the two classes overlap, membership is not always
easily established. The picture is complicated by the occasional presence of
softer, extended emission lasting tens of seconds after the initial spike-like
emission. We show that the fundamental defining characteristic of the short
burst class is that the initial spike exhibits negligible spectral evolution at
energies above ~ 25 keV. This behavior is nearly ubiquitous for the 260 bursts
with T90 < 2 s, where the BATSE TTE data completely included the initial spike.
The same signature obtains for one HETE-2 and six Swift/BAT short bursts.
Analysis of a small sample of "short" BATSE bursts with the most intense
extended emission shows that the same lack of evolution on the pulse timescale
obtains for the extended emission. The dynamic range in the ratio of peak
intensities, spike : extended, is ~ 10^4. For some bursts, the extended
emission is only a factor of 2-5 less intense. A high Lorentz factor, ~
500-1000, might explain the negligible lags observed in short bursts.


title: Comments on the Cooperstock-Tieu Galaxy Model

abstract:
  The recently proposed Cooperstock-Tieu galaxy model claims to explain the
flat rotation curves without dark matter. The purpose of this note is to show
that this model is internally inconsistent and thus cannot be considered a
valid solution. Moreover, by making the solution consistent the ability to
explain the flat rotation curves is lost.


title:
X-ray Emission of Baryonic Gas in the Universe: Luminosity-Temperature
  Relationship and Soft-Band Background

abstract:
  We study the X-ray emission of baryon fluid in the universe using the WIGEON
cosmological hydrodynamic simulations. It has been revealed that cosmic baryon
fluid in the nonlinear regime behaves like Burgers turbulence, i.e. the fluid
field consists of shocks. Like turbulence in incompressible fluid, the Burgers
turbulence plays an important role in converting the kinetic energy of the
fluid to thermal energy and heats the gas. We show that the simulation sample
of the $\Lambda$CDM model without adding extra heating sources can fit well the
observed distributions of X-ray luminosity versus temperature ($L_{\rm x}$ vs.
$T$) of galaxy groups and is also consistent with the distributions of X-ray
luminosity versus velocity dispersion ($L_{\rm x}$ vs. $\sigma$). Because the
baryonic gas is multiphase, the $L_{\rm x}-T$ and $L_{\rm x}-\sigma$
distributions are significantly scattered. If we describe the relationships by
power laws $L_{\rm x}\propto T^{\alpha_{LT}}$ and $L_{\rm x}\propto
\sigma^{\alpha_{LV}}$, we find $\alpha_{LT}>2.5$ and $\alpha_{LV}>2.1$. The
X-ray background in the soft $0.5-2$ keV band emitted by the baryonic gas in
the temperature range $10^5<T<10^7$ K has also been calculated. We show that of
the total background, (1) no more than 2% comes from the region with
temperature less than $10^{6.5}$ K, and (2) no more than 7% is from the region
of dark matter with mass density $\rho_{\rm dm}<50 \bar{\rho}_{\rm dm}$. The
region of $\rho_{\rm dm}>50\bar{\rho}_{\rm dm}$ is generally clustered and
discretely distributed. Therefore, almost all of the soft X-ray background
comes from clustered sources, and the contribution from truly diffuse gas is
probably negligible. This point agrees with current X-ray observations.


title: Centrifugal Breakout of Magnetically Confined Line-Driven Stellar Winds

abstract:
  We present 2D MHD simulations of the radiatively driven outflow from a
rotating hot star with a dipole magnetic field aligned with the star's rotation
axis. We focus primarily on a model with moderately rapid rotation (half the
critical value), and also a large magnetic confinement parameter, $\eta_{\ast}
\equiv B_{\ast}^2 R_{\ast}^{2} / \dot{M} V_{\infty} = 600$. The magnetic field
channels and torques the wind outflow into an equatorial, rigidly rotating disk
extending from near the Kepler corotation radius outwards. Even with
fine-tuning at lower magnetic confinement, none of the MHD models produce a
stable Keplerian disk. Instead, material below the Kepler radius falls back on
to the stellar surface, while the strong centrifugal force on material beyond
the corotation escape radius stretches the magnetic loops outwards, leading to
episodic breakout of mass when the field reconnects. The associated dissipation
of magnetic energy heats material to temperatures of nearly $10^{8}$K, high
enough to emit hard (several keV) X-rays. Such \emph{centrifugal mass ejection}
represents a novel mechanism for driving magnetic reconnection, and seems a
very promising basis for modeling X-ray flares recently observed in rotating
magnetic Bp stars like $\sigma$ Ori E.


title:
On the variation of the fine-structure constant: Very high resolution
  spectrum of QSO HE 0515-4414

abstract:
  We present a detailed analysis of a very high resolution (R\approx 112,000)
spectrum of the quasar HE 0515-4414 obtained using the High Accuracy Radial
velocity Planet Searcher (HARPS) mounted on the ESO 3.6 m telescope at the La
Silla observatory. The HARPS spectrum, of very high wavelength calibration
accuracy (better than 1 m\AA), is used to search for possible systematic
inaccuracies in the wavelength calibration of the UV Echelle Spectrograph
(UVES) mounted on the ESO Very Large Telescope (VLT). We have carried out
cross-correlation analysis between the Th-Ar lamp spectra obtained with HARPS
and UVES. The shift between the two spectra has a dispersion around zero of
\sigma\simeq 1 m\AA. This is well within the wavelength calibration accuracy of
UVES (i.e \sigma\simeq 4 m\AA). We show that the uncertainties in the
wavelength calibration induce an error of about, \Delta\alpha/\alpha\le
10^{-6}, in the determination of the variation of the fine-structure constant.
Thus, the results of non-evolving \Delta\alpha/\alpha reported in the
literature based on UVES/VLT data should not be heavily influenced by problems
related to wavelength calibration uncertainties. Our higher resolution spectrum
of the z_{abs}=1.1508 damped Lyman-\alpha system toward HE 0515-4414 reveals
more components compared to the UVES spectrum. Using the Voigt profile
decomposition that simultaneously fits the high resolution HARPS data and the
higher signal-to-noise ratio UVES data, we obtain,
\Delta\alpha/\alpha=(0.05\pm0.24)x10^{-5} at z_{abs}=1.1508. This result is
consistent with the earlier measurement for this system using the UVES spectrum
alone.


title: Optical Detection of Galaxy Clusters

abstract:
  This chapter provides an overview of past and present techniques for optical
detection of galaxy clusters. It follows the progression of cluster detection
techniques through time, allowing readers to understand the development of the
field while explaining the variety of data and methodologies applied. Within
each section we describe the datasets and algorithms used, pointing out their
strengths and important limitations, especially with respect to the
characterizability of the resulting catalogs. The next section provides a
historical overview of pre-digital, photographic surveys that formed the basis
for most cluster studies until the start of the twenty-first century. Section
three describes the hybrid photo-digital surveys that created the largest
current cluster catalogs. The fourth section is devoted to fully digital
surveys, most specifically the Sloan Digital Sky Survey and the variety of
methods used for cluster detection. We also describe smaller surveys, mostly
for higher redshift systems. The fifth section gives an overview of the
different algorithms used by these surveys, with an eye towards future
improvements. The concluding section discusses various tests that remain to be
done to fully understand any of the catalogs produced by these surveys, so that
they can be compared to simulations.


title:
Spectral analysis of the background in ground-based, long-slit
  spectroscopy

abstract:
  This paper examines the variations, because of atmospheric extinction, of
broad-band visible spectra, obtained from long-slit spectroscopy, in the
vicinity of some stars, nebulae, and one faint galaxy.


title: An analysis of spectra in the Red Rectangle nebula

abstract:
  This paper presents an analysis of a series of spectra in the Red Rectangle
nebula. Only the reddest part of the spectra can safely be attributed to light
from the nebula, and indicates Rayleigh scattering by the gas, in conformity
with the large angles of scattering involved and the proximity of the star. In
the blue, light from HD44179, refracted or scattered in the atmosphere,
dominates the spectra. This paper questions the reliability of ground-based
observations of extended objects in the blue.


title: Nucleosynthesis In Core Collapse Supernovae

abstract:
  We present the basic properties of the yields of our latest set of
presupernova evolution and explosive nucleosynthesis of massive stars in the
range between 11 and 120 Msun having solar and zero metallicity.


title:
Automated analysis of eclipsing binary lightcurves. I. EBAS -- a new
  Eclipsing Binary Automated Solver with EBOP

abstract:
  We present a new algorithm -- Eclipsing Binary Automated Solver (EBAS), to
analyse lightcurves of eclipsing binaries. The algorithm is designed to analyse
large numbers of lightcurves, and is therefore based on the relatively fast
EBOP code. To facilitate the search for the best solution, EBAS uses two
parameter transformations. Instead of the radii of the two stellar components,
EBAS uses the sum of radii and their ratio, while the inclination is
transformed into the impact parameter. To replace human visual assessment, we
introduce a new 'alarm' goodness-of-fit statistic that takes into account
correlation between neighbouring residuals. We perform extensive tests and
simulations that show that our algorithm converges well, finds a good set of
parameters and provides reasonable error estimation.


title:
The association between gas and galaxies I: CFHT spectroscopy and pair
  analysis

abstract:
  We investigate the relative distribution of the gaseous contents of the
Universe (as traced by a sample of Lyman alpha (lya) absorbers), and the
luminous baryonic matter (as traced by a redshift survey of galaxies in the
same volume searched for lya absorbers), along 16 lines-of-sight (LOS) between
redshifts 0 and 1. Our galaxy redshift survey was made with the Multi-Object
Spectrograph (MOS) on Canada-France-Hawaii Telescope (CFHT) and, when combined
with galaxies from the literature in the same LOS, gives us a galaxy sample of
636 objects. By combining this with an absorption line sample of 406 absorbing
systems drawn from published works, we are able to study the relationship
between gas and galaxies over the latter half of the age of the Universe. A
correlation between absorbers and galaxies is detected out to separation of 1.5
Mpc. This correlation is weaker than the galaxy-galaxy correlation. There is
also some evidence that the absorbing systems seen in CIV are more closely
related to galaxies, although this correlation could be with column density
rather than metallicity. The above results are all consistent with the
absorbing gas and the galaxies co-existing in dark matter filaments and knots
as predicted by current models, where the column density of the absorbing gas
is correlated with the underlying matter density.


title:
Automated analysis of eclipsing binary lightcurves with EBAS. II.
  Statistical analysis of OGLE LMC eclipsing binaries

abstract:
  In the first paper of this series we presented EBAS, a new fully automated
algorithm to analyse the lightcurves of eclipsing binaries, based on the EBOP
code. Here we apply the new algorithm to the whole sample of 2580 binaries
found in the OGLE LMC photometric survey and derive the orbital elements for
1931 systems. To obtain the statistical properties of the short-period binaries
of the LMC we construct a well defined subsample of 938 eclipsing binaries with
main-sequence B-type primaries. Correcting for observational selection effects,
we derive the distributions of the fractional radii of the two components and
their sum, the brightness ratios and the periods of the short-period binaries.
Somewhat surprisingly, the results are consistent with a flat distribution in
log P between 2 and 10 days. We also estimate the total number of binaries in
the LMC with the same characteristics, and not only the eclipsing binaries, to
be about 5000. This figure leads us to suggest that 0.7 +- 0.4 percent of the
main-sequence B-type stars in the LMC are found in binaries with periods
shorter than 10 days. This frequency is substantially smaller than the fraction
of binaries found by small Galactic radial-velocity surveys of B stars. On the
other hand, the binary frequency found by HST photometric searches within the
late main-sequence stars of 47 Tuc is only slightly higher and still consistent
with the frequency we deduced for the B stars in the LMC.


title: Did Galaxy Assembly and Supermassive Black-Hole Growth go hand-in-hand?

abstract:
  In this paper, we address whether the growth of supermassive black-holes has
kept pace with the process of galaxy assembly. For this purpose, we first
searched the Hubble Ultra Deep Field (HUDF) for "tadpole galaxies", which have
a knot at one end and an extended tail. They appear dynamically unrelaxed --
presumably early-stage mergers -- and make up ~6% of the field galaxy
population. Their redshift distribution follows that of field galaxies,
indicating that -- if tadpole galaxies are indeed dynamically young -- the
process of galaxy assembly generally kept up with the reservoir of field
galaxies as a function of epoch. Next, we present a search for HUDF objects
with point-source components that are optically variable (at the >~3.0 sigma
level) on timescales of weeks--months. Among 4644 objects to i_AB=28.0 mag (10
sigma), 45 have variable point-like components, which are likely weak AGN.
About 1% of all field objects show variability for 0.1 < z < 4.5, and their
redshift distribution is similar to that of field galaxies. Hence supermassive
black-hole growth in weak AGN likely also kept up with the process of galaxy
assembly. However, the faint AGN sample has almost no overlap with the tadpole
sample, which was predicted by recent hydrodynamical numerical simulations.
This suggests that tadpole galaxies are early-stage mergers, which likely
preceded the ``turn-on'' of the AGN component and the onset of visible
point-source variability by >~1 Gyr.


title:
Observations of the Cosmic Microwave Background and Galactic Foregrounds
  at 12-17 GHz with the COSMOSOMAS Experiment

abstract:
  (Abridged) We present the analysis of the first 18 months of data obtained
with the COSMOSOMAS experiment at the Teide Observatory (Tenerife). Three maps
have been obtained at 12.7, 14.7 and 16.3 GHz covering 9000 square degrees each
with a resolution of ~1 degree and with sensitivities 49, 59 and 115 muK per
beam respectively. These data in conjuction with the WMAP first year maps have
revealed that the Cosmic Microwave Background (CMB) is the dominant
astronomical signal at high galatic latitude in the three COSMOSOMAS channels
with an average amplitude of 29.7+/- 1.0 \muK (68% c.l. not including
calibration errors). This value is in agreement with the predicted CMB signal
in the COSMOSOMAS maps using the best fit Lambda-CDM model to the WMAP power
spectrum. Cross-correlation of COSMOSOMAS data with the DIRBE map at 100 \mu m
shows the existence of a common signal with amplitude 7.4+/- 1.1, 7.5+/- 1.1,
and 6.5+/-2.3 muK in the 12.7, 14.7 and 16.3 GHz COSMOSOMAS maps at
|b|>30^\deg. Using the WMAP data we find this DIRBE correlated signal rises
from high to low frequencies flattening below ~20 GHz. At higher galactic
latitudes the average amplitude of the correlated signal with the DIRBE maps
decreases slightly. The frequency behaviour of the COSMOSOMAS/WMAP correlated
signal with DIRBE is not compatible with the expected tendency for thermal
dust. A study of the H-alpha emission maps do not support free-free as a major
contributor to that signal. Our results provide evidence of a new galactic
foreground with properties compatible with those predicted by the spinning dust
models.


title:
Mid-infrared Spitzer spectra of X-ray selected Type 2 QSOs: QSO2s are
  not ULIRGs

abstract:
  We have performed a spectroscopic study of 7 Type 2 QSOs using the
mid-infrared spectrometer IRS on board the Spitzer Space Telescope. These are
(to our knowledge) the first mid-IR spectra of X-ray selected QSO2s taken. The
objects have been selected according to their high intrinsic luminosities and
column densities in the X-rays. Their spectra strongly differ from template
spectra of Type 2 AGN at lower luminosities. They do not exhibit strong PAH
dust emission features from circum-nuclear star forming regions, typical for
lower luminosity Type 2 Seyfert galaxies or other previously used QSO2
templates, such as the (Ultra)luminous Infrared Galaxy ((U)LIRG) NGC 6240. They
also do not show the ice and silicate absorption features of highly luminous
but deeply embedded compact nuclei seen in some ULIRGs. Instead they reveal a
relatively featureless, rising continuum similar to luminous Type 1 AGN. We
also find evidence for a 10 micron silicate feature in emission. Models of
dusty tori in the AGN unification scenario predict this only for Type 1 AGN.
The ratio of the AGN continuum luminosity at 6 micron to the absorption
corrected 2-10keV X-ray AGN luminosity is very similar to that found in Seyfert
galaxies. X-ray selected QSO2s are thus characterized by powerful AGN in hosts
with a luminosity due to star formation < 1e11 L_sol. The dominance of the AGN
light in the mid-IR spectra of QSO2s together with their flatter spectral
energy distributions (SEDs) places important constraints on models of the
cosmic infrared background and of the star formation history of the universe.


title: The ultra-cool white dwarf companion of PSR J0751+1807

abstract:
  We present optical and near-infrared observations with Keck of the binary
millisecond pulsar PSR J0751+1807. We detect a faint, red object - with
R=25.08+-0.07, B-R=2.5+-0.3, and R-I=0.90+-0.10 - at the celestial position of
the pulsar and argue that it is the white dwarf companion of the pulsar. The
colours are the reddest among all known white dwarfs, and indicate a very low
temperature, Teff~4000 K. This implies that the white dwarf cannot have the
relatively thick hydrogen envelope that is expected on evolutionary grounds.
Our observations pose two puzzles. First, while the atmosphere was expected to
be pure hydrogen, the colours are inconsistent with this composition. Second,
given the low temperature, irradiation by the pulsar should be important, but
we see no evidence for it. We discuss possible solutions to these puzzles.


title: An Inverse Look at the Center of M15

abstract:
  The observed radial and transverse velocities of individual stars in M15 are
implemented as inputs to a fully non-parametric code (CHASSIS) in order to
estimate the equilibrium stellar distribution function and the
three-dimensional mass density profile. In particular, the paper explores the
possibility of the existence of a central black hole in M15 via several runs
that utilize the radial velocity data set which offers kinematic measurements
closer to the centre of the cluster than the proper motion data. These runs are
distinguished from each other in the choice of the initial seed for the cluster
characteristics; however, the profiles identified by the algorithm at the end
of each run concur with each other, within error bars, thus confirming the
robustness of CHASSIS. The recovered density profiles are noted to exhibit
unequivocal flattening, inner to about 0.0525pc. Also, the enclosed mass
profile is very close to being a power-law function of radius inside 0.1pc and
is not horizontal. Simplistically speaking, these trends negate the possibility
of the central mass to be concentrated in a black hole, the lower bound on the
radius of the sphere of influence of which would be $\gtrsim$0.041pc, had it
existed. However, proper analysis suggests that the mass enclosed within the
inner 0.01pc could be in the form of a black hole of mass
$\sim{10^3}$M$_{\odot}$, under two different scenarios, which are discussed.
The line-of-sight velocity dispersion is visually found to be very similar to
the observed dispersion profile. The enclosed mass and velocity dispersion
profiles calculated from runs done with the proper motion data are found to be
consistent with the profiles obtained with the radial velocity data.


title:
Mining for normal galaxies in the First XMM-Newton Serendipitous Source
  Catalog

abstract:
  This paper uses the 1st XMM Serendipitous Source Catalog compiled by the XMM
Science Center to identify low-z X-ray selected normal galaxy candidates. Our
sample covers a total area of ~6deg^2 to the 0.5-2keV limit 1e-15cgs. A total
of 23 sources are selected on the basis of low X-ray-to-optical flux ratio
logfx/fopt<-2, soft X-ray spectral properties and optical spectra, when
available, consistent with stellar than AGN processes. This sample is combined
with similarly selected systems from the Needles in the Haystack Survey
(Georgantopoulos et al. 2005) to provide a total of 46 z<0.2 X-ray detected
normal galaxies, the largest low-z sample yet available. This is first used to
constrain the normal galaxy logN-logS at bright fluxes (>1e-15cgs). We estimate
a slope of -1.46\pm0.13 for the cumulative number counts consistent with the
euclidean prediction. We further combine our sample with 23 local (z<0.2)
galaxies from the CDF North and South to construct the local X-ray luminosity
function of normal galaxies. A Schechter form provides a good fit to the data
with a break at logL*~41.02cgs and a slope of -1.76\pm0.10. Finally, for the
sample of 46 systems we explore the association between X-ray luminosity and
host galaxy properties, such as SFR and stellar mass. We find that the L_X of
the emission-line systems correlates with Ha luminosity and 1.4GHz radio power,
both providing an estimate of the current star-formation rate. In the case of
early type galaxies with absorption line optical spectra we use the K-band as
proxy to stellar mass and find a correlation of the form L_X~L_K^1.5. This is
flatter than the L_X-L_B relation for local ellipticals. This may be due to
either L_K providing a better proxy to galaxy mass or selection effects biasing
our sample against very luminous early-type galaxies.


title:
Luminosity distance for Born-Infeld electromagnetic waves propagating in
  a cosmological magnetic background

abstract:
  Born-Infeld electromagnetic waves interacting with a static magnetic
background are studied in an expanding universe. The non-linear character of
Born-Infeld electrodynamics modifies the relation between the energy flux and
the distance to the source, which gains a new dependence on the redshift that
is governed by the background field. We compute the luminosity distance as a
function of the redshift and compare with Maxwellian curves for supernovae type
Ia.


title:
Radial Distribution of Planets. Predictions based on the Core Accretion
  Gas Capture Planet formation Model

abstract:
  We have investigated the problem of the distribution of both masses and
orbital radii of planets resulting from the gas-accretion, gas-capture model.
First we followed the evolution of gas and solids from the moment where all
solids are in the form of small grains to the stage when most of them are in
the form of planetesimals for a set of different initial masses and sizes of
protoplanetary disks. Based on that we performed Monte Carlo calculations
describing the formation of giant places at different locations. We included
the effects of type II migration and growth of the mass of the planet after the
gap opened. We discuss how these effects influence the final distribution of
giant planets. We show that when the giant planets are not able to migrate or
grow in mass after the gap opens, their distribution is mainly determined by
the properties of the gaseous disk. However, with those two effects included,
reproducing the parameters of the gaseous disks from the distribution of
planets becomes difficult. We also checked the roles of both the material of
which the solids consist and the mass of the central star. The main result is
that, in disks around less massive stars, giant planets at the given location
tend to be less massive. At the same time, the giant planets with the given
mass tend to form closer to the less massive stars.


title: NLTE Strontium and Barium in metal poor red giant stars

abstract:
  We present atmospheric models of red giant stars of various metallicities,
including extremely metal poor (XMP, [Fe/H]<-3.5) models, with many chemical
species, including, significantly, the first two ionization stages of Strontium
(Sr) and Barium (Ba), treated in Non-Local Thermodynamic Equilibrium (NLTE)
with various degrees of realism. We conclude that 1) for all lines that are
useful Sr and Ba abundance diagnostics the magnitude and sense of the computed
NLTE effect on the predicted line strength is metallicity dependent, 2) the
indirect NLTE effect of overlap between Ba and Sr transitions and transitions
of other species that are also treated in NLTE non-negligibly enhances NLTE
abundance corrections for some lines, 3) the indirect NLTE effect of NLTE
opacity of other species on the equilibrium structure of the atmospheric model
is not significant, 4) the computed NLTE line strengths differ negligibly if
collisional b-b and b-f rates are an order of magnitude smaller or larger than
those calculated with standard analytic formulae, and 5) the effect of NLTE
upon the resonance line of Ba II at 4554.03 AA is independent of whether that
line is treated with hyperfine splitting. As a result, the derivation of
abundances of Ba and Sr for metal-poor red giant stars with LTE modeling that
are in the literature should be treated with caution.


title: Accretion torque on magnetized neutron stars

abstract:
  The conventional picture of disk accretion onto magnetized neutron stars has
been challenged by the spin changes observed in a few X-ray pulsars, and by
theoretical results from numerical simulations of disk-magnetized star
interactions. These indicate possible accretion during the propeller regime and
the spin-down torque increasing with the accretion rate. Here we present a
model for the accretion torque exerted by the disk on a magnetized neutron
star, assuming accretion continues even for rapid rotators. The accretion
torque is shown to have some different characteristics from that in the
conventional model, but in accord with observations and numerical calculations
of accretion-powered magnetized neutron stars. We also discuss its possible
applications to the spin evolution in X-ray pulsars.


title: Radial velocities of population II binary stars. II

abstract:
  Here we publish the second list of radial velocities for 91 Hipparcos stars,
mostly high transverse velocity binaries without previous radial velocity
measurements. The measurements of radial velocities are done with a
CORAVEL-type radial velocity spectrometer with an accuracy better than 1 km/s.
We also present the information on eight new radial velocity variables - HD
29696, HD 117466AB, BD +28 4035AB, BD +30 2129A, BD +39 1828AB, BD +69 230A, BD
+82 565A and TYC 2267-1300-1 - found from our measurements. Two stars (HD
27961AB and HD 75632AB) are suspected as possible radial velocity variables.