title:
HI studies of eXtremely Metal Deficient galaxies - II: GMRT observations
  of SBS 1129+576

abstract:
  We present GMRT HI observations of an eXtremely Metal Deficient (XMD) galaxy
SBS 1129+576 (12 + log(O/H) = 7.41). Our HI observations show that the galaxy
is strongly interacting with a companion galaxy, SBS 1129+577. A third, smaller
galaxy, SDSS J113227.68+572142.3, is also present in the data cube. Our
low-resolution map shows a bridge of emission connecting the two larger
galaxies and a large one-armed spiral distortion of the disc of SBS 1129+577.
Assuming that most of the bridge gas originally came from SBS 1129+576, ~1/3 of
its original gas mass has been stripped off. The third smaller galaxy does not
show any sign of interaction with the other two galaxies. The higher resolution
maps show that SBS 1129+577 has a central bar and a ring surrounding the bar;
there is also a hint of an integral-shaped warp in SBS 1129+576. All these
features are very likely to have been induced by the tidal interaction. In both
SBS 1129+576 and SBS 1129+577, there is, in general, a good correspondence
between regions with high HI column density and those with ongoing star
formation. The inclination-corrected HI column density in the two brightest HII
regions in SBS 1129+576 and near the HII regions in SBS 1129+577 is generally
above the threshold density for star formation observed in other blue compact
galaxies. (abridged)


title: Dark Satellites and Cosmic Reionization

abstract:
  A possible explanation of the present discrepancy between the abundance of
galactic subhaloes predicted by N-Body simulations with those observed in the
Local Group is presented. We study the impact of an early reionization on the
baryonic component of the Universe using SPH simulations on group and galactic
scales. We use a simplified model for reionization described as an
instantaneous increment of the IGM temperature (with 1e5<T_{IGM}<1e6 K) at a
given redshift (z_r > 8). We find that a key role is played by compton cooling
(interaction between hot electrons and the CMB photons); at high redshift
(z_r>10) this cooling is very efficient and it is able to counteract any
heating of the gas within few Myrs. This means that a late reionization is
needed (z_r<9) to sufficiently reduce the number of luminous dwarf satellites
around our Galaxy. For a reionization redshift z_r=8 and a reionization
temperature of T_{IGM}~1e5 K we are able to reproduce the observed number of
Local Group dwarf galaxies in our simulations.


title: Steerable wavelet analysis of CMB structures alignment

abstract:
  This paper reviews the application of a novel methodology for analysing the
isotropy of the universe by probing the alignment of local structures in the
CMB. The strength of the proposed methodology relies on the steerable wavelet
filtering of the CMB signal. One the one hand, the filter steerability renders
the computation of the local orientation of the CMB features affordable in
terms of computation time. On the other hand, the scale-space nature of the
wavelet filtering allows to explore the alignment of the local structures at
different scales, probing possible different phenomena. We present the WMAP
first-year data analysis recently performed by the same authors (Wiaux et al.),
where an extremely significant anisotropy was found. In particular, a preferred
plane was detected, having a normal direction with a northern end position
close to the northern end of the CMB dipole axis. In addition, a most preferred
direction was found in that plane, with a northern end direction very close to
the north ecliptic pole. This result synthesised for the first time previously
reported anomalies identified in the direction of the dipole and the ecliptic
poles axes. In a forthcoming paper (Vielva et al.), we have extended our
analysis to the study of individual frequency maps finding first indications
for discarding foregrounds as the origin of the anomaly. We have also tested
that the preferred orientations are defined by structures homogeneously
distributed in the sky, rather than from localised regions. We have also
analysed the WMAP 3-year data, finding the same anomaly pattern, although at a
slightly lower significance level.


title:
HI studies of the Sculptor group galaxies. VIII. The background
  galaxies: NGC 24 and NGC 45

abstract:
  In order to complete our HI survey of galaxies in the Sculptor group area,
VLA observations of NGC 24 and NGC 45 are presented. These two galaxies of
similar magnitude M_B ~ -17.4 lie in the background of the Sculptor group and
are low surface brightness galaxies, especially NGC 45. The HI distribution and
kinematics are regular for NGC 24 while NGC 45 exhibits a kinematical twist of
its major axis. A tilted-ring model shows that the position angle of the major
axis changes by ~25 degrees. A best-fit model of their mass distribution gives
mass-to-light ratios for the stellar disk of 2.5 and 5.2 for NGC 24 and NGC 45
respectively. These values are higher than the ones expected from stellar
population synthesis models. Despite the large dark matter contribution, the
galaxy mass is still dominated by the stellar component in their very inner
regions. These high mass-to-light ratios are typical of what is seen in low
surface brightness galaxies and may indicate that, in those galaxies, disks are
far from the maximum disk case. The halo parameters derived from the best-fit
models are thus lower limits.


title: Results from MAGIC's first observation cycle on galactic sources

abstract:
  During its Cycle I, the MAGIC telescope targeted about 250 hours several
galactic sources sought to be, or detected previously by other experiments in
the same energy domain, gamma-ray emitters. This paper reviews some results of
such MAGIC observations covering, among others, supernova remnants, the
Galactic Center and microquasars. We will concentrate on the recent discovery
at very high energy gamma-rays of the microquasar LS I +61 303.


title: On the multiwavelength spectrum of the microquasar 1E 1740.7-2942

abstract:
  Context. The microquasar 1E 1740.7-2942 is a source located in the direction
of the Galactic Center. It has been detected at X-rays, soft gamma-rays, and in
the radio band, showing an extended radio component in the form of a
double-sided jet. Although no optical counterpart has been found so far for 1E
1740.7-2942, its X-ray activity strongly points to a galactic nature. Aims. We
aim to improve our understanding of the hard X-ray and gamma-ray production in
the system, exploring whether the jet can emit significantly at high energies
under the light of the present knowledge. Methods. We have modeled the source
emission, from radio to gamma-rays, with a cold-matter dominated jet model.
INTEGRAL data combined with radio and RXTE data, as well as EGRET and HESS
upper-limits, are used to compare the computed and the observed spectra.
Results. From our modeling, we find out that jet emission cannot explain the
high fluxes observed at hard X-rays without violating at the same time the
constraints from the radio data, favoring the corona origin of the hard X-rays.
Also, 1E 1740.7-2942 might be detected by GLAST or AGILE at GeV energies, and
by HESS and HESS-II beyond 100 GeV, with the spectral shape likely affected by
photon-photon absorption in the disk and corona photon fields.


title: Heating of the Intergalactic Medium by Primordial Miniquasars

abstract:
  A simple analytical model is used to calculate the X-ray heating of the IGM
for a range of black hole masses. This process is efficient enough to decouple
the spin temperature of the intergalactic medium from the cosmic microwave
background (CMB) temperature and produce a differential brightness temperature
of the order of $\sim 5-20 \mathrm{mK}$ out to distances as large as a few
co-moving Mpc, depending on the redshift, black hole mass and lifetime. We
explore the influence of two types of black holes, those with and without
ionising UV radiation. The results of the simple analytical model are compared
to those of a full spherically symmetric radiative transfer code. Two simple
scenarios are proposed for the formation and evolution of black hole mass
density in the Universe. The first considers an intermediate mass black hole
that form as an end-product of Population III stars, whereas the second
considers super-massive black holes that form directly through the collapse of
massive halos with low spin parameter. These scenarios are shown not to violate
any of the observational constraints, yet produce enough X-ray photons to
decouple the spin-temperature from that of the CMB. This is an important issue
for future high redshift 21 cm observations.


title: Observations of Extragalactic Sources with the MAGIC Telescope

abstract:
  MAGIC is currently the world's largest single dish ground based imaging
atmospheric Cherenkov telescope. During the first year of operation, more than
20 extragalactic sources have been observed and several of them detected. Here
we present results of analyzed data, including discussion about spectral and
temporal properties of the detected sources. In addition, we discuss
implications of the measured energy spectra of distant sources for our
knowledge of the extragalactic background light.


title:
Dynamo Action in the Solar Convection Zone and Tachocline: Pumping and
  Organization of Toroidal Fields

abstract:
  We present the first results from three-dimensional spherical shell
simulations of magnetic dynamo action realized by turbulent convection
penetrating downward into a tachocline of rotational shear. This permits us to
assess several dynamical elements believed to be crucial to the operation of
the solar global dynamo, variously involving differential rotation resulting
from convection, magnetic pumping, and amplification of fields by stretching
within the tachocline. The simulations reveal that strong axisymmetric toroidal
magnetic fields (about 3000 G in strength) are realized within the lower stable
layer, unlike in the convection zone where fluctuating fields are predominant.
The toroidal fields in the stable layer possess a striking persistent
antisymmetric parity, with fields in the northern hemisphere largely of
opposite polarity to those in the southern hemisphere. The associated mean
poloidal magnetic fields there have a clear dipolar geometry, but we have not
yet observed any distinctive reversals or latitudinal propagation. The presence
of these deep magnetic fields appears to stabilize the sense of mean fields
produced by vigorous dynamo action in the bulk of the convection zone.


title:
Timing of millisecond pulsars in NGC 6752 - II. Proper motions of the
  pulsars in the cluster outskirts

abstract:
  Exploiting a five-year span of data, we present improved timing solutions for
the five millisecond pulsars known in the globular cluster NGC 6752. They
include proper motion determinations for the two outermost pulsars in the
cluster, PSR J1910-5959A and PSR J1910-5959C. The values of the proper motions
are in agreement with each other within current uncertainties, but do not match
(at 4 sigma and 2 sigma level respectively) with the value of the proper motion
of the entire globular cluster derived in the optical band. Implications of
these results for the cluster membership of the two pulsars are investigated.
Prospects for the detection of the Shapiro delay in the binary system
J1910-5959A are also discussed.


title:
CURious Variables Experiment (CURVE). CCD Photometry and Variable Stars
  in the field of open cluster NGC 637

abstract:
  We present VI photometry for the open cluster NGC 637 which is located in the
Cassiopeia region. Morphology of cluster color-magnitude diagram indicates that
it is a young object with age of a few million years. The apparent distance
modulus of the cluster is 13.9<(m-M)_V<14.3, while reddening is
0.69<E(V-I)<0.73. We estimated the heliocentric distance as 2.6<d<3.3 kpc. We
also report the identification of two variable stars in NGC 637. One of the
variables is a non-radial pulsating beta Cep-type star. Other one is a likely
ellipsoidal variable, however its pulsating nature can not be excluded.


title:
Sun-as-a-star observations: evidence for degree dependence of changes in
  damping of low-l p modes along the solar cycle

abstract:
  We use 9.5-yr of BiSON Sun-as-a-star data to search for dependence of
solar-cycle parameter changes on the angular degree, l, of the data. The nature
of the Sun-as-a-star observations is such that for changes measured at fixed
frequency, or for changes averaged across the same range in frequency, any l
dependence present carries information on the latitudinal distribution of the
agent (i.e., the activity) responsible for those changes. We split the 9.5-yr
timeseries into contiguous 108-d pieces, and determine mean changes in the
damping of, power in, and energy supplied to the modes through the solar cycle.
We also apply a careful correction to account for the deleterious effects of
the ground-based BiSON window function on the results. From our full analysis
we obtain a marginally significant result for the damping parameter, where the
mean change is found to be weakest at l=0. The other parameters show hints of
some dependence in l. Our main conclusion is that the mean fractional
solar-cycle change in the l=0 damping rates is approximately 50 % smaller than
was previously assumed. It had been common practice to use an average over all
low-l modes; our downward revision of the radial-mode value has implications
for comparisons with models of the global solar cycle changes, which are
usually based on a spherically symmetric geometry.


title:
Spitzer-IRS spectra of disks around T Tauri stars II. PAH emission
  features

abstract:
  Aims: We search for PAH features towards T Tauri stars and compare them with
surveys of Herbig Ae/Be stars. The presence and strength of the PAH features
are interpreted with disk radiative transfer models exploring the PAH feature
dependence on the incident UV radiation, PAH abundance and disk parameters.
  Methods: Spitzer Space Telescope 5-35 micron spectra of 54 pre-main sequence
stars with disks were obtained, consisting of 38 T Tauri, 7 Herbig Ae/Be and 9
stars with unknown spectral type.
  Results: Compact PAH emission is detected towards at least 8 sources of which
5 are Herbig Ae/Be stars. The 11.2 micron PAH feature is detected in all of
these sources, as is the 6.2 micron PAH feature where short wavelength data are
available. However, the 7.7 and 8.6 micron features appear strongly in only 1
of these 4 sources. PAH emission is observed towards at least 3 T Tauri stars
(8% detection rate). The lowest mass source with PAHs in our sample is T Cha
(G8). All 4 sources in our sample with evidence for dust holes in their inner
disk show PAH emission, increasing the feature/continuum ratio. Typical 11.2
micron line intensities are an order of magnitude lower than those observed for
the more massive Herbig Ae/Be stars. Measured line fluxes indicate PAH
abundances that are factors of 10-100 lower than standard interstellar values.
Conversely, PAH features from disks exposed to stars with Teff<=4200K without
enhanced UV are predicted to be below the current detection limit, even for
high PAH abundances. Disk modeling shows that the 6.2 and 11.2 micron features
are the best PAH tracers for T Tauri stars, whereas the 7.7 and 8.6 micron
bands have low feature over continuum ratios due to the strongly rising
silicate emission.


title:
Viscous overstability and eccentricity evolution in three-dimensional
  gaseous discs

abstract:
  We investigate the growth or decay rate of the fundamental mode of even
symmetry in a viscous accretion disc. This mode occurs in eccentric discs and
is known to be potentially overstable. We determine the vertical structure of
the disc and its modes, treating radiative energy transport in the diffusion
approximation. In the limit of very long radial wavelength, an analytical
criterion for viscous overstability is obtained, which involves the effective
shear and bulk viscosity, the adiabatic exponent and the opacity law of the
disc. This differs from the prediction of a two-dimensional model. On shorter
wavelengths (a few times the disc thickness), the criterion for overstability
is more difficult to satisfy because of the different vertical structure of the
mode. In a low-viscosity disc a third regime of intermediate wavelengths
appears, in which the overstability is suppressed as the horizontal velocity
perturbations develop significant vertical shear. We suggest that this effect
determines the damping rate of eccentricity in protoplanetary discs, for which
the long-wavelength analysis is inapplicable and overstability is unlikely to
occur on any scale. In thinner accretion discs and in decretion discs around Be
stars overstability may occur only on the longest wavelengths, leading to the
preferential excitation of global eccentric modes.


title: A directional continuous wavelet transform on the sphere

abstract:
  A new construction of a directional continuous wavelet analysis on the sphere
is derived herein. We adopt the harmonic scaling idea for the spherical
dilation operator recently proposed by Sanz et al. but extend the analysis to a
more general directional framework. Directional wavelets are a powerful
extension that allow one to also probe oriented structure in the analysed
function. Our spherical wavelet methodology has the advantage that all
functions and operators are defined directly on the sphere. The construction of
wavelets in our framework is demonstrated with an example.


abstract:
  (abridged:) The XMM-Newton Extended Survey of the Taurus Molecular Cloud
(XEST) surveys the most populated ~5 square degrees of the Taurus star
formation region, using the XMM-Newton X-ray observatory to study the thermal
structure, variability, and long-term evolution of hot plasma, to investigate
the magnetic dynamo, and to search for new potential members of the
association. Many targets are also studied in the optical, and high-resolution
X-ray grating spectroscopy has been obtained for selected bright sources. The
X-ray spectra have been coherently analyzed with two different thermal models
(2-component thermal model, and a continuous emission measure distribution
model). We present overall correlations with fundamental stellar parameters
that were derived from the previous literature. A few detections from Chandra
observations have been added. The present overview paper introduces the project
and provides the basic results from the X-ray analysis of all sources detected
in the XEST survey.Comprehensive tables summarize the stellar properties of all
targets surveyed. The survey goes deeper than previous X-ray surveys of Taurus
by about an order of magnitude and for the first time systematically accesses
very faint and strongly absorbed TMC objects. We find a detection rate of 85%
and 98% for classical and weak-line T Tau stars (CTTS resp. WTTS), and identify
about half of the surveyed protostars and brown dwarfs. Overall, 136 out of 169
surveyed stellar systems are detected. We describe an X-ray luminosity vs. mass
correlation, discuss the distribution of X-ray-to-bolometric luminosity ratios,
and show evidence for lower X-ray luminosities in CTTS compared to WTTS.
Detailed analysis (e.g., variability, rotation-activity relations, influence of
accretion on X-rays) will be discussed in a series of accompanying papers.


title: Astronomy with Small Telescopes

abstract:
  The All Sky Automated Survey (ASAS) is monitoring all sky to about 14 mag
with a cadence of about 1 day; it has discovered about 10^5 variable stars,
most of them new. The instrument used for the survey had aperture of 7 cm. A
search for planetary transits has lead to the discovery of about a dozen
confirmed planets, so called 'hot Jupiters', providing the information of
planetary masses and radii. Most discoveries were done with telescopes with
aperture of 10 cm.
  We propose a search for optical transients covering all sky with a cadence of
10 - 30 minutes and the limit of 12 - 14 mag, with an instant verification of
all candidate events. The search will be made with a large number of 10 cm
instruments, and the verification will be done with 30 cm instruments.
  We also propose a system to be located at the L_1 point of the Earth - Sun
system to detect 'killer asteroids'. With a limiting magnitude of about 18 mag
it could detect 10 m boulders several hours prior to their impact, provide
warning against Tunguska-like events, as well as to provide news about
spectacular but harmless more modest impacts.


title: Monte Carlo Simulations of Metal-Poor Star Clusters

abstract:
  Metal-poor globular clusters (GCs) can provide a probe of the earliest epoch
of star formation in the Universe, being the oldest stellar systems observable.
In addition, young and intermediate-age low-metallicity GCs are present in
external galaxies. Nevertheless, inferring their evolutionary status by using
integrated properties may suffer from large \emph{intrinsic} uncertainty caused
by the discrete nature of stars in stellar systems, especially in the case of
faint objects. In this paper, we evaluate the \emph{intrinsic} uncertainty (due
to statistical effects) affecting the integrated colours and mass--to--light
ratios as a function of the cluster integrated visual magnitude ($M_V^{tot}$),
which represents a quantity directly measured. Our approach is based on Monte
Carlo techniques for randomly generating stars distributed according to the
cluster's mass function. Integrated colours and mass--to--light ratios in
different photometric bands are checked to be in good agreement with the
observational values of low-metallicity Galactic clusters. We present
integrated colours and mass--to--light ratios as a function of age for
different assumptions on the cluster total $V$ magnitude. We find that the
emph{intrinsic} uncertainty cannot be neglected. In particular, in models with
$M_V^{tot}=-4$ the broad-band colours show an \emph{intrinsic} uncertainty so
high as to prevent precise age evaluation of the cluster. Finally, the present
predictions are compared with recent results available in the literature,
showing in some cases non-negligible differences.


title:
Estimating the Dark Halo Mass from the Relative Thickness of Stellar
  Disks

abstract:
  We analyze the relationship between the mass of a spherical component and the
minimum possible thickness of stable stellar disks. This relationship for real
galaxies allows the lower limit on the dark halo mass to be estimated (the
thinner the stable stellar disk is, the more massive the dark halo must be). In
our analysis, we use both theoretical relations and numerical N-body
simulations of the dynamical evolution of thin disks in the presence of
spherical components with different density profiles and different masses. We
conclude that the theoretical relationship between the thickness of disk
galaxies and the mass of their spherical components is a lower envelope for the
model data points. We recommend using this theoretical relationship to estimate
the lower limit for the dark halo mass in galaxies. The estimate obtained turns
out to be weak. Even for the thinnest galaxies, the dark halo mass within four
exponential disk scale lengths must be more than one stellar disk mass.


title: The linear stability of dilute particulate rings

abstract:
  Irregular structure in planetary rings is often attributed to the intrinsic
instabilities of a homogeneous state undergoing Keplerian shear. Previously
these have been analysed with simple hydrodynamic models. We instead employ a
kinetic theory, in which we solve the linearised moment equations derived in
Shu and Stewart 1985 for a dilute ring. This facilitates an examination of
velocity anisotropy and non-Newtonian stress, and their effects on the viscous
and viscous/gravitational instabilities thought to occur in Saturn's rings.
Because we adopt a dilute gas model, the applicability of our results to the
actual dense rings of Saturn are significantly curtailled. Nevertheless this
study is a necessary preliminary before an attack on the difficult problem of
dense ring dynamics. We find the Shu and Stewart formalism admits analytic
stability criteria for the viscous overstability, viscous instability, and
thermal instability. These criteria are compared with those of a hydrodynamic
model incorporating the effective viscosity and cooling function computed from
the kinetic steady state. We find the two agree in the `hydrodynamic limit'
(i.e. many collisions per orbit) but disagree when collisions are less
frequent, when we expect the viscous stress to be increasingly non-Newtonian
and the velocity distribution increasingly anisotropic. In particular,
hydrodynamics predicts viscous overstability for a larger portion of parameter
space. We also numerically solve the linearised equations of the more accurate
Goldreich and Tremaine 1978 kinetic model and discover its linear stability to
be qualitatively the same as that of Shu and Stewart's. Thus the simple
collision operator adopted in the latter would appear to be an adequate
approximation for dilute rings, at least in the linear regime.


title: How accurate is Limber's equation?

abstract:
  The so-called Limber equation is widely used in the literature to relate the
projected angular clustering of galaxies to the spatial clustering of galaxies
in an approximate way. This paper gives estimates of where the regime of
applicability of Limber's equation stops. Limber's equation is accurate for
small galaxy separations but breaks down beyond a certain separation that
depends mainly on the ratio sigma/R and to some degree on the power-law index,
gamma, of spatial clustering xi; sigma is the one-sigma width of the galaxy
distribution in comoving distance, and R the mean comoving distance. As
rule-of-thumb, a 10% relative error is reached at 260 sigma/R arcmin for
gamma~1.6, if the spatial clustering is a power-law. More realistic xi are
discussed in the paper. Limber's equation becomes increasingly inaccurate for
larger angular separations. Ignoring this effect and blindly applying Limber's
equation can possibly bias results for the inferred spatial correlation. It is
suggested to use in cases of doubt, or maybe even in general, the exact
equation that can easily be integrated numerically in the form given in the
paper.


title: On the cosmological mass function theory

abstract:
  This paper provides, from one side, a review of the theory of the
cosmological mass function from a theoretical point of view, starting from the
seminal paper of Press & Shechter (1974) to the last developments (Del Popolo &
Gambera (1998, 1999), Sheth & Tormen 1999 (ST), Sheth, Mo & Tormen 2001 (ST1),
Jenkins et al. 2001 (J01), Shet & Tormen 2002 (ST2), Del Popolo 2002a, Yagi et
al. 2004 (YNY)), and from another side some improvements on the multiplicity
function models in literature. ...


title: Gravitational collapse and non-self similarity in the L-T relation

abstract:
  We derive the luminosity-temperature relation for clusters of galaxies by
means of a modification of the self-similar model to take account of angular
momentum acquisition by protostructures and of an external pressure term in the
virial theorem. The fundamental result of the model is that gravitational
collapse, which takes account of angular momentum acquisition, can explain the
non self-similarity in the L-T relation, in disagreement with the largely
accepted assumption that heating/cooling processes and similar are fundamental
in the originating the non-self similar behavior (shaping) of the L-T relation.


title: High-energy gamma-ray emission in AGNs and microquasars

abstract:
  I review here some of the main observational features in microquasars and
AGNs as sources of high-energy gamma-rays as well as some of the current models
that try to explain the emission in the gamma-ray domain.


title:
Evolution of the K-band Galaxy Cluster Luminosity Function and Scaling
  Relations

abstract:
  We study the evolution of two fundamental properties of galaxy clusters: the
luminosity function (LF) and the scaling relations between the total galaxy
number N (or luminosity) and cluster mass M. Using a sample of 27 clusters
(0<z<0.9) with new near-IR observations and mass estimates derived from X-ray
temperatures, in conjunction with data from the literature, we construct the
largest sample for such studies to date. The evolution of the characteristic
luminosity of the LF can be described by a passively evolving population formed
in a single burst at z=1.5-2. Under the assumption that the mass-temperature
relation evolves self-similarly, and after the passive evolution is accounted
for, the N-M scaling shows no signs of evolution out to z=0.9. Our data provide
direct constraints on halo occupation distribution models, and suggest that the
way galaxies populate cluster-scale dark matter halos has not changed in the
past 7 Gyr, in line with previous investigations.


title:
The ERO Host Galaxy of GRB 020127: Implications for the Metallicity of
  GRB Progenitors

abstract:
  We present optical and near-IR observations of the host galaxy of GRB 020127,
for which we measure R-K=6.2 mag. This is only the second GRB host to date,
which is classified as an ERO. The spectral energy distribution is typical of a
dusty starburst galaxy, with a redshift, z~1.9, a luminosity, L~5L*, and an
inferred stellar mass of ~10^11-10^12 Msun, two orders of magnitude more
massive than typical GRB hosts. A comparison to the z~2 mass-metallicity (M-Z)
relation indicates that the host metallicity is about 0.5 Zsun. This result
shows that at least some GRBs occur in massive, metal-enriched galaxies, and
that the proposed low metallicity bias of GRB progenitors is not as severe as
previously claimed. Instead we propose that the blue colors and sub-L*
luminosities of most GRB hosts reflect their young starburst populations. This,
along with the locally increased fraction of starbursts at lower stellar mass,
may in fact be the underlying reason for the claimed low metallicity bias of
z<0.2 GRB hosts. Consequently, GRBs and their host galaxies may serve as a
reliable tracer of cosmic star formation, particularly at z>1 where the M-Z
relation is systematically lower, and the star formation rate is dominated by
sub-L* galaxies.


title:
Large Area Mapping at 850 Microns. V. Analysis of the Clump Distribution
  in the Orion A South Molecular Cloud

abstract:
  We present results from a 2300 arcmin^2 survey of the Orion A molecular cloud
at 450 and 850 micron using the Submillimetre Common-User Bolometer Array
(SCUBA) on the James Clerk Maxwell Telescope. The region mapped lies directly
south of the OMC1 cloud core and includes OMC4, OMC5, HH1/2, HH34, and L1641N.
We identify 71 independent clumps in the 850 micron map and compute size, flux,
and degree of central concentration in each. Comparison with isothermal,
pressure-confined, self-gravitating Bonnor-Ebert spheres implies that the
clumps have internal temperatures T_d ~ 22 +/- K and surface pressures log
(k^-1 P cm^-3 K) = 6.0 +/- 0.2. The clump masses span the range 0.3 - 22 Msun
assuming a dust temperature T_d ~ 20 K and a dust emissivity kappa_850 = 0.02
cm^2 g^-1. The distribution of clump masses is well characterized by a
power-law N(M) propto M^-alpha with alpha = 2.0 +/- 0.5 for M > 3.0 Msun,
indicating a clump mass function steeper than the stellar Initial Mass
Function. Significant incompleteness makes determination of the slope at lower
masses difficult. A comparison of the submillimeter emission map with an H_2
2.122 micron survey of the same region is performed. Several new Class 0
sources are revealed and a correlation is found between both the column density
and degree of concentration of the submillimeter sources and the likelihood of
coincident H_2 shock emission.


title: The Final Merger of Comparable Mass Binary Black Holes

abstract:
  A remarkable series of breakthroughs in numerical relativity modeling of
black hole binary mergers has occurred over the past few years. This paper
provides a general overview of these exciting developments, focusing on recent
progress in merger simulations and calculations of the resulting gravitational
waveforms.


title: GRB Fireball Physics: Prompt and Early Emission

abstract:
  We review the fireball shock model of gamma-ray burst prompt and early
afterglow emission in light of rapid follow-up measurements made and enabled by
the multi-wavelength Swift satellite. These observations are leading to a
reappraisal and expansion of the previous standard view of the GRB and its
fireball. New information on the behavior of the burst and afterglow on minutes
to hour timescales has led, among other results, to the discovery and follow-up
of short GRB afterglows, the opening up of the z>6 redshift range, and the
first prompt multi-wavelength observations of a long GRB-supernova. We discuss
the salient observational results and some associated theoretical issues.


title:
Theoretical calculations of the HI, HeI and HeII free-bound continuou
  emission spectra

abstract:
  We present coefficients for the calculation of the continuous emission
spectra of HI, HeI and HeII due to electron-ion recombination. Coefficients are
given for photon energies from the first ionization threshold for each ion to
the n=20 threshold of hydrogen (36.5um), and for temperatures 100 K <= Te
<=10^5 K. The emission coefficients for HeI are derived from accurate ab initio
photoionization data. The coefficients are scaled in such a way that they may
be interpolated by a simple scheme with uncertainties less than 1% in the whole
temperature and wavelength domain. The data are suitable for incorporation into
photoionisation/plasma codes and should aid with the interpretation of spectra
from the very cold ionised gas phase inferred to exist in a number of gaseous
clouds.


title:
Nearby early-type galaxies with ionized gas. III. Analysis of
  line-strength indices with new stellar population models

abstract:
  In this paper we study the underlying stellar population of a sample of 65
nearby early-type galaxies predominantly located in low density environments.
Ages, metallicities and [alpha/Fe] ratios have been derived through the
comparison of Lick indices measured at different galacto-centric distances with
new SSP models which account for the presence of alpha/Fe enhancement. The SSPs
cover a wide range of ages, metallicities and [alpha/Fe] ratios. To derive the
stellar population parameters we have devised an algorithm based on the
probability density function. We derive a large spread in age ((1-15) Gyrs).
Age does not show any significant trend with central velocity dispersion
sigma_c but E galaxies appear on average older than S0. On the contrary, an
increasing trend of metallicity and [alpha/Fe] with sigma_c is observed,
testifying that the chemical enrichment was more efficient and the duration of
the star formation shorter in more massive galaxies. We have also sought for
possible correlations with the local galaxy density but neither metallicity nor
alpha-enhancement show clear trends. However we find that while low density
environments (LDE) contain very young objects (from 1 to 4 Gyr), none of the
galaxies in the higher density environments (HDE) is younger than 5 Gyrs.
Considering the lack of environmental effect on the [alpha/Fe] ratio and the
high value of [alpha/Fe] in some young massive objects, we argue that young
galaxies in LDE are more likely due to recent rejuvenation episodes. By
comparing the number of rejuvenated objects with the total number of galaxies
in our sample, and by means of simple two-SSP component models, we estimate
that, on average, the rejuvenation episodes do not involve more than 25 % of
the total galaxy mass.


title:
Two Bipolar Outflows and Magnetic Fields in a Multiple Protostar System,
  L1448 IRS 3

abstract:
  We performed spectral line observations of CO J=2-1, 13CO J=1-0, and C18O
J=1-0 and polarimetric observations in the 1.3 mm continuum and CO J=2-1 toward
a multiple protostar system, L1448 IRS 3, in the Perseus molecular complex at a
distance of ~250 pc, using the BIMA array. In the 1.3 mm continuum, two sources
(IRS 3A and 3B) were clearly detected with estimated envelope masses of 0.21
and 1.15 solar masses, and one source (IRS 3C) was marginally detected with an
upper mass limit of 0.03 solar masses. In CO J=2-1, we revealed two outflows
originating from IRS 3A and 3B. The masses, mean number densities, momentums,
and kinetic energies of outflow lobes were estimated. Based on those estimates
and outflow features, we concluded that the two outflows are interacting and
that the IRS 3A outflow is nearly perpendicular to the line of sight. In
addition, we estimated the velocity, inclination, and opening of the IRS 3B
outflow using Bayesian statistics. When the opening angle is ~20 arcdeg, we
constrain the velocity to ~45 km/s and the inclination angle to ~57 arcdeg.
Linear polarization was detected in both the 1.3 mm continuum and CO J=2-1. The
linear polarization in the continuum shows a magnetic field at the central
source (IRS 3B) perpendicular to the outflow direction, and the linear
polarization in the CO J=2-1 was detected in the outflow regions, parallel or
perpendicular to the outflow direction. Moreover, we comprehensively discuss
whether the binary system of IRS 3A and 3B is gravitationally bound, based on
the velocity differences detected in 13CO J=1-0 and C18O J=1-0 observations and
on the outflow features. The specific angular momentum of the system was
estimated as ~3e20 cm^2/s, comparable to the values obtained from previous
studies on binaries and molecular clouds in Taurus.


title: Magnetic Fields in the Formation of Sun-Like Stars

abstract:
  We report high-angular-resolution measurements of polarized dust emission
toward the low-mass protostellar system NGC 1333 IRAS 4A. We show that in this
system the observed magnetic field morphology is in agreement with the standard
theoretical models of the formation of Sun-like stars in magnetized molecular
clouds at scales of a few hundred astronomical units; gravity has overcome
magnetic support, and the magnetic field traces a clear hourglass shape. The
magnetic field is substantially more important than turbulence in the evolution
of the system, and the initial misalignment of the magnetic and spin axes may
have been important in the formation of the binary system.


title:
The 2dF-SDSS LRG and QSO Survey: The Star Formation Histories of
  Luminous Red Galaxies

abstract:
  We present a detailed investigation into the recent star formation histories
of 5,697 Luminous Red Galaxies (LRGs) based on the Hdelta (4101A) and [OII]
(3727A) lines. LRGs are luminous (L>3L*), galaxies which have been selected to
have photometric properties consistent with an old, passively evolving stellar
population. For this study we utilise LRGs from the recently completed 2dF-SDSS
LRG and QSO survey (2SLAQ). Equivalent widths of the Hdelta and [OII] lines are
measured and used to define three spectral types, those with only strong Hdelta
absorption (k+a), those with strong [OII] in emission (em) and those with both
(em+a). All other LRGs are considered to have passive star formation histories.
The vast majority of LRGs are found to be passive (~80 per cent), however
significant numbers of k+a (2.7 per cent), em+a (1.2 per cent) and em LRGs (8.6
per cent) are identified. An investigation into the redshift dependence of the
fractions is also performed. A sample of SDSS MAIN galaxies with colours and
luminosities consistent with the 2SLAQ LRGs is selected to provide a low
redshift comparison. While the em and em+a fractions are consistent with the
low redshift SDSS sample, the fraction of k+a LRGs is found to increase
significantly with redshift. This result is interpreted as an indication of an
increasing amount of recent star formation activity in LRGs with redshift. By
considering the expected life time of the k+a phase, the number of LRGs which
will undergo a k+a phase can be estimated. A crude comparison of this estimate
with the predictions from semi-analytic models of galaxy formation shows that
the predicted level of k+a and em+a activity is not sufficient to reconcile the
predicted mass growth for massive early-types in a hierarchical merging
scenario.


title: Detecting UHE Cosmics & Neutrinos off the Moon; an Optimal Radio Window

abstract:
  We show that at wavelengths comparable to the length of the shower produced
by an Ultra-High Energy cosmic ray or neutrino, radio signals are an extremely
efficient way to detect these particles. Through an example it is shown that
this new approach offers, for the first time, the realistic possibility of
measuring UHE neutrino fluxes below the Waxman-Bahcall limit. It is shown that
in only one month of observing with the upcoming LOFAR radio telescope,
cosmic-ray events can be measured beyond the GZK-limit, at a sensitivity level
of two orders of magnitude below the extrapolated values.


title: Dim Isolated Neutron Stars, Cooling and Energy Dissipation

abstract:
  The cooling and reheating histories of dim isolated neutron stars(DINs) are
discussed. Energy dissipation due to dipole spindown with ordinary and magnetar
fields, and due to torques from a fallback disk are considered as alternative
sources of reheating which would set the temperature of the neutron star after
the initial cooling era. Cooling or thermal ages are related to the numbers and
formation rates of the DINs and therefore to their relations with other
isolated neutron star populations. Interaction with a fallback disk, higher
multipole fields and activity of the neutron star are briefly discussed.


title: Thermal Emission from HII Galaxies: Discovering the Youngest Systems

abstract:
  We studied the radio properties of very young massive regions of star
formation in HII galaxies, with the aim of detecting episodes of recent star
formation in an early phase of evolution where the first supernovae start to
appear. Our sample consists of 31 HII galaxies, characterized by strong
Hydrogen emission lines, for which low resolution VLA 3.5cm and 6cm
observations were obtained. The radio spectral energy distribution has a range
of behaviours; 1) there are galaxies where the SED is characterized by a
synchrotron-type slope, 2) galaxies with a thermal slope, and, 3) galaxies with
possible free-free absorption at long wavelengths. The latter SEDs were found
in a few galaxies and represent a signature of heavily embedded massive star
clusters closely related to the early stages of massive star formation. Based
on the comparison of the star formation rates determined from the recombination
lines and those determined from the radio emission we find that SFR(Ha) is on
average five times higher than SFR(1.4GHz). We confirm this tendency by
comparing the ratio between the observed flux at 20 cm and the expected one,
calculated based on the Ha star formation rates, both for the galaxies in our
sample and for normal ones. This analysis shows that this ratio is a factor of
2 smaller in our galaxies than in normal ones, indicating that they fall below
the FIR/radio correlation. These results suggest that the emission of these
galaxies is dominated by a recent and massive star formation event in which the
first supernovae (SN) just started to explode. We conclude that the systematic
lack of synchrotron emission in those systems with the largest equivalent width
of Hb can only be explained if those are young starbursts of less than 3.5Myr
of age.


title: X-rays from jet-driving protostars and T Tauri stars

abstract:
  (abridged:) We study X-rays from jet-driving protostars and T Tau stars. We
seek soft spectral components that may be due to shock emission, and
shock-induced emission displaced from the stellar position. Two stellar samples
are used, the first consisting of lightly absorbed T Tau stars with strong
jets, the other containing protostars with disks seen nearly edge-on. The
former sample was observed in the XMM-Newton Extended Survey of the Taurus
Molecular Cloud (XEST), while Chandra archival data provided observations of
the latter. We confirm the previously identified peculiar spectrum of DG Tau A
and find similar phenomenology in GV Tau and DP Tau, suggesting a new class of
X-ray spectra. These consist of a lightly absorbed, very soft component and a
strongly absorbed, very hard component. The latter is flaring while little
variability is detected in the former. The absorption of the harder component
is about an order of magnitude higher than expected from the optical extinction
assuming a standard gas-to-dust mass ratio. The flaring hard component
represents active coronal emission. Its strong absorption is attributed to mass
inflow from the accretion disk. The optical extinction is small because the
dust has sublimated at larger distances. The weakly absorbed soft component
cannot originate from the same location. Because the stars drive strong jets,
we propose that the X-rays are generated in shocks in the jets. We find that
for the three peculiar X-ray sources, the luminosity of the soft component
roughly scales with the equivalent width of the [OI] 6300A line formed in the
jets, and with the mass outflow rate. In the more strongly obscured protostars,
the soft component is entirely absorbed, and only the hard, coronal component
penetrates the envelope or the near-edge-on disk.


title:
Impact of neutron star oscillations on the accelerating electric field
  in the polar cap of pulsar: or could we see oscillations of the neutron star
  after the glitch in pulsar?

abstract:
  Pulsar "standard model", that considers a pulsar as a rotating magnetized
conducting sphere surrounded by plasma, is generalized to the case of
oscillating star. We developed an algorithm for calculation of the
Goldreich-Julian charge density for this case. We consider distortion of the
accelerating zone in the polar cap of pulsar by neutron star oscillations. It
is shown that for oscillation modes with high harmonic numbers (l,m) changes in
the Goldreich-Julian charge density caused by pulsations of neutron star could
lead to significant altering of an accelerating electric field in the polar cap
of pulsar. In the moderately optimistic scenario, that assumes excitation of
the neutron star oscillations by glitches, it could be possible to detect
altering of the pulsar radioemission due to modulation of the accelerating
field.


title: Irradiated ISM: Discriminating between Cosmic Rays and X-rays

abstract:
  The ISM of active galaxy centers is exposed to a combination of cosmic ray,
FUV and X-ray radiation. We apply PDR models to this ISM with both `normal' and
highly elevated (5\times 10^{-15}s^-1) cosmic-ray rates and compare the results
to those obtained for XDRs. Our existing PDR-XDR code is used to construct
models over a 10^3-10^5 cm^-3 density range and for 0.16-160 erg s^-1 cm^-2
impingent fluxes. We obtain larger high J (J>10) CO ratios in PDRs when we use
the highly elevated cosmic ray rate, but these are always exceeded by the
corresponding XDR ratios. The [CI] 609 mum/13CO(2-1) line ratio is boosted by a
factor of a few in PDRs with n~10^3 cm^-3 exposed to a high cosmic ray rate. At
higher densities ratios become identical irrespective of cosmic ray flux, while
XDRs always show elevated [CI] emission per CO column. The HCN/CO and HCN/HCO+
line ratios, combined with high J CO emission lines, are good diagnostics to
distinguish between PDRs under either low or high cosmic ray irradiation
conditions, and XDRs. Hence, the HIFI instrument on Herschel, which can detect
these CO lines, will be crucial in the study of active galaxies.


title:
The BH mass of nearby QSOs: a comparison of the bulge luminosity and
  virial methods

abstract:
  We report on the analysis of the photometric and spectroscopic properties of
a sample of 29 low redshift (z<0.6) QSOs for which both HST WFPC2 images and
ultraviolet HST FOS spectra are available. For each object we measure the R
band absolute magnitude of the host galaxy, the CIV (1550A) line width and the
1350A continuum luminosity. From these quantities we can estimate the black
hole (BH) mass through the M(BH)-L(bulge) relation for inactive galaxies, and
from the virial method based on the kinematics of the regions emitting the
broad lines. The comparison of the masses derived from the two methods yields
information on the geometry of the gas emitting regions bound to the massive
BH. The cumulative distribution of the line widths is consistent with that
produced by matter laying in planes with inclinations uniformly distributed
between 10 and 50 deg, which corresponds to a geometrical factor f=1.3. Our
results are compared with those of the literature and discussed within the
unified model of AGN.


title:
Formation and destruction of polycyclic aromatic hydrocarbon clusters in
  the interstellar medium

abstract:
  The competition between the formation and destruction of coronene clusters
under interstellar conditions is investigated theoretically. The unimolecular
nucleation of neutral clusters is simulated with an atomic model combining an
explicit classical force field and a quantum tight-binding approach.
Evaporation rates are calculated in the framework of the phase space theory and
are inserted in an infrared emission model and compared with the growth rate
constants. It is found that, in interstellar conditions, most collisions lead
to cluster growth. The time evolution of small clusters (containing up to 312
carbon atoms) was specifically investigated under the physical conditions of
the northern photodissociation region of NGC 7023. These clusters are found to
be thermally photoevaporated much faster than they are reformed, thus providing
an interpretation for the lowest limit of the interstellar cluster size
distribution inferred from observations. The effects of ionizing the clusters
and density heterogeneities are also considered. Based on our results, the
possibility that PAH clusters could be formed in PDRs is critically discussed.


title: Discovery of a Young Substellar Companion in Chamaeleon

abstract:
  During an imaging survey of the Chamaeleon I star-forming region with the ACS
aboard HST, we have discovered a candidate substellar companion to the young
low-mass star CHXR 73 (~2 Myr, M=0.35 Msun). We measure a projected separation
of 1.3+/-0.03" for the companion, CHXR 73 B, which corresponds to 210 AU at the
distance of the cluster. A near-infrared spectrum of this source obtained with
CorMASS at the Magellan II telescope exhibits strong steam absorption that
confirms its late-type nature (>=M9.5). In addition, the gravity-sensitive
shapes of the H- and K-band continua demonstrate that CHXR 73 B is a young,
pre-main-sequence object rather than a field star. The probability that CHXR
73A and B are unrelated members of Chamaeleon I is ~0.001. We estimate the
masses of CHXR 73 B and other known substellar companions in young clusters
with a method that is consistent with the dynamical measurements of the
eclipsing binary brown dwarf 2M 0535-0546, which consists of a comparison of
the bolometric luminosities of the companions to the values predicted by the
evolutionary models of Chabrier & coworkers and Burrows & coworkers. We arrive
at mass estimates of 0.003-0.004, 0.024+/-0.012, 0.011+0.01/-0.003, and
0.012+0.008/-0.005 Msun for 2M 1207-3932 B, GQ Lup B, DH Tau B, and CHXR 73 B,
respectively. Thus, DH Tau B and CHXR 73 B appear to be the least massive
companions to stars outside the solar system that have been detected in direct
images, and may have masses that are within the range observed for extrasolar
planetary companions (M<=0.015 Msun). However, because these two objects (as
well as 2M 1207-3932 B) probably did not form within circumstellar disks around
their primaries, we suggest that they should be viewed as brown dwarf
companions rather than planets.


title: Can extragalactic foregrounds explain the large-angle CMB anomalies?

abstract:
  We address the effect of an extended local foreground on the low-l anomalies
found in the CMB. Recent X-ray catalogues point us to the existence of very
massive superstructures at the 100 h^(-1) Mpc scale that contribute
significantly to the dipole velocity profile. Being highly non-linear, these
structures provide us a natural candidate to leave an imprint on the CMB sky
via a local Rees-Sciama effect. We show that the Rees-Sciama effect of local
foregrounds can induce CMB anisotropy of DeltaT/T ~ 10^(-5) and we analyse its
impact on multipole power as well as the induced phase pattern on largest
angular scales.


title: CDMS, Supersymmetry and Extra Dimensions

abstract:
  The CDMS experiment aims to directly detect massive, cold dark matter
particles originating from the Milky Way halo. Charge and lattice excitations
are detected after a particle scatters in a Ge or Si crystal kept at ~30 mK,
allowing to separate nuclear recoils from the dominating electromagnetic
background. The operation of 12 detectors in the Soudan mine for 75 live days
in 2004 delivered no evidence for a signal, yielding stringent limits on dark
matter candidates from supersymmetry and universal extra dimensions. Thirty Ge
and Si detectors are presently installed in the Soudan cryostat, and operating
at base temperature. The run scheduled to start in 2006 is expected to yield a
one order of magnitude increase in dark matter sensitivity.


title: Electrodynamics for Nuclear Matter in Bulk

abstract:
  A general approach to analyze the electrodynamics of nuclear matter in bulk
is presented using the relativistic Thomas-Fermi equation generalizing to the
case of $N \simeq (m_{\rm Planck}/m_n)^3$ nucleons of mass $m_n$ the approach
well tested in very heavy nuclei ($Z \simeq 10^6$). Particular attention is
given to implement the condition of charge neutrality globally on the entire
configuration, versus the one usually adopted on a microscopic scale. As the
limit $N \simeq (m_{\rm Planck}/m_n)^3$ is approached the penetration of
electrons inside the core increases and a relatively small tail of electrons
persists leading to a significant electron density outside the core. Within a
region of $10^2$ electron Compton wavelength near the core surface electric
fields close to the critical value for pair creation by vacuum polarization
effect develop. These results can have important consequences on the
understanding of physical process in neutron stars structures as well as on the
initial conditions leading to the process of gravitational collapse to a black
hole.


title:
Properties of the galaxy population in hydrodynamical simulations of
  clusters

abstract:
  We present a study of the galaxy population predicted by hydrodynamical
simulations for a set of 19 galaxy clusters based on the GADGET-2 Tree+SPH
code. These simulations include gas cooling, star formation, a detailed
treatment of stellar evolution and chemical enrichment, as well as SN energy
feedback in the form of galactic winds. We compute the spectro-photometric
properties of the simulated galaxies. All simulations have been performed for
two choices of the stellar initial mass function: a standard Salpeter IMF, and
a top-heavier IMF. Several of the observational properties of the galaxy
population in nearby clusters are reproduced fairly well by simulations. A
Salpeter IMF is successful in accounting for the slope and the normalization of
the color-magnitude relation for the bulk of the galaxy population. Simulated
clusters have a relation between mass and optical luminosity which generally
agrees with observations, both in normalization and slope. We find that
galaxies are generally bluer, younger and more star forming in the cluster
outskirts, thus reproducing the observational trends. However, simulated
clusters have a total number of galaxies which is significantly smaller than
the observed one, falling short by about a factor 2-3. Finally, the brightest
cluster galaxies are always predicted to be too massive and too blue, when
compared to observations, due to gas overcooling in the core cluster regions,
even in the presence of a rather efficient SN feedback.


title: Critical Mass Transfer in Double-Degenerate Type Ia Supernovae

abstract:
  Doubly-degenerate binary systems consisting of two white dwarfs both composed
of carbon and oxygen and close enough that mass is transferred from the less
massive to the more massive are possible progenitors of type Ia supernovae. If
the mass transfer rate is slow enough that the accreting white dwarf can reach
1.38 solar masses then it can ignite carbon degenerately at its centre. This
can lead to a thermonuclear runaway and thence a supernova explosion. However
if the accretion rate is too high the outer layers of the white dwarf heat up
too much and carbon ignites there non-degenerately. A series of mild carbon
flashes can then propagate inwards and convert the carbon to neon relatively
gently. There is no thermonuclear runaway and no supernova. We have determined
the critical rate for accretion and find it to be generally about two-fifths of
the Eddington rate. In the case of actual bianry stars the mass transfer rate
falls off as mass is transferred so we find that this rate can be very much
exceeded at the onset of mass transfer. We determine combinations of white
dwarf masses that can lead to central degenerate carbon ignition.


title:
Unbinned maximum-likelihood estimators for low-count data: Applications
  to faint X-ray spectra in the Taurus Molecular Cloud

abstract:
  Traditional binned statistics such as $\chi^2$ suffer from information loss
and arbitrariness of the binning procedure. We point out that the underlying
statistical quantity (the log likelihood $L$) does not require any binning
beyond the one implied by instrumental readout channels, and we propose to use
it for low-count data. The performance of $L$ in the model classification and
point estimation problems is explored by Monte-Carlo simulations of Chandra and
XMM X-ray spectra, and is compared to the performances of the binned Poisson
statistic ($C$), Pearson's $\chi^2$ and Neyman's $\chi^2_N$, the Kolmogorov-
Smirnov, and Kuiper' statistics. It is found that the unbinned log likelihood
$L$ performs best with regard to the expected chi-square distance between true
and estimated spectra, the chance of a successful identification among discrete
candidate models, the area under the receiver-operator curve of reduced
(two-model) binary classification problems, and generally also with regard to
the mean square errors of individual spectrum parameters. The $\chi^2$
($\chi^2_{\rm N}$) statistics should only be used if more than 10 (15)
predicted counts per bin are available. From the practical point of view, the
computational cost of evaluating $L$ is smaller than for any of the alternative
methods if the forward model is specified in terms of a Poisson intensity and
normalization is a free parameter. The maximum-$L$ method is applied to 14
observations from the Taurus Molecular Cloud, and the unbinned results are
compared to binned XSPEC results, and found to generally agree, with exceptions
explained by instability under re-binning and by background fine structures.
The maximum-$L$ method has no lower limit on the available counts, and allows
to treat weak sources which are beyond the means of binned methods.


title: Persistent and Transient Blank Field Sources

abstract:
  Blank field sources (BFS) are good candidates for hosting dim isolated
neutron stars (DINS). The results of a search of BFS in the ROSAT HRI images
are revised. We then focus on transient BFS, arguing that they belong to a
rather large population. The perspectives of future research on DINS are then
discussed.


title:
Biomarkers in disk-averaged near-UV to near-IR Earth spectra using
  Earthshine observations

abstract:
  We analyse the detectability of vegetation on a global scale on Earth's
surface. Considering its specific reflectance spectrum showing a sharp edge
around 700 nm, vegetation can be considered as a potential global biomarker.
This work, based on observational data, aims to characterise and to quantify
this signature in the disk-averaged Earth's spectrum. Earthshine spectra have
been used to test the detectability of the "Vegetation Red Edge" (VRE) in the
Earth spectrum. We obtained reflectance spectra from near UV (320 nm) to near
IR (1020 nm) for different Earth phases (continents or oceans seen from the
Moon) with EMMI on the NTT at ESO/La Silla, Chile. We accurately correct the
sky background and take into account the phase-dependent colour of the Moon.
VRE measurements require a correction of the ozone Chappuis absorption band and
Rayleigh plus aerosol scattering. Results : The near-UV spectrum shows a dark
Earth below 350 nm due to the ozone absorption. The Vegetation Red Edge is
observed when forests are present (4.0% for Africa and Europe), and is lower
when clouds and oceans are mainly visible (1.3% for the Pacific Ocean). Errors
are typically $\pm0.5$, and $\pm1.5$ in the worst case. We discuss the
different sources of errors and bias and suggest possible improvements. We
showed that measuring the VRE or an analog on an Earth-like planet remains very
difficult (photometric relative accuracy of 1% or better). It remains a small
feature compared to atmospheric absorption lines. A direct monitoring from
space of the global (disk-averaged) Earth's spectrum would provide the best VRE
follow-up.


title:
VLT/FORS spectroscopy of faint cataclysmic variables discovered by the
  Sloan Digital Sky Survey

abstract:
  We present medium-resolution VLT/FORS2 spectroscopy of six cataclysmic
variables discovered by the Sloan Digital Sky Survey. We determine orbital
periods for SDSS J023322.61+005059.5 (96.08 +/- 0.09 min), SDSS
J091127.36+084140.7 (295.74 +/- 0.22 min), SDSS J103533.02+055158.3 (82.10 +/-
0.09 min), and SDSS J121607.03+052013.9 (most likely 98.82 +/- 0.16 min, but
the one-day aliases at 92 min and 107 min are also possible) using radial
velocities measured from their H_alpha and H_beta emission lines. Three of the
four orbital periods measured here are close to the observed 75--80 min minimum
period for cataclysmic variables, indicating that the properties of the
population of these objects discovered by the SDSS are substantially different
to those of the cataclysmic variables found by other means. Additional
photometry of SDSS J023322.61+005059.5 reveals a periodicity of approximately
60 min which we interpret as the spin period of the white dwarf, suggesting
that this system is an intermediate polar with a low accretion rate. SDSS
J103533.02+055158.3 has a period right at the observed minimum value, a
spectrum dominated by the cool white dwarf primary star and exhibits deep
eclipses, so is an excellent candidate for an accurate determination of the
parameters of the system. The spectroscopic orbit of SDSS J121607.03+052013.9
has a velocity amplitude of only 13.8 +/- 1.6 km/s, implying that this system
has an extreme mass ratio. From several physical constraints we find that this
object must contain either a high-mass white dwarf or a brown-dwarf-mass
secondary component or both.


title:
Different Power-law Indices in the Frequency Distributions of Flares
  with and without Coronal Mass Ejections

abstract:
  We investigated the frequency distributions of flares with and without
coronal mass ejections (CMEs) as a function of flare parameters (peak flux,
fluence, and duration of soft X-ray flares). We used CMEs observed by the Large
Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric
Observatory (SOHO) mission and soft X-ray flares (C3.2 and above) observed by
the GOES satellites during 1996 to 2005. We found that the distributions obey a
power-law of the form: dN/dX~X^-alpha, where X is a flare parameter and dN is
the number of events recorded within the interval [X, X+dX]. For the flares
with (without) CMEs, we obtained the power-law index alpha=1.98+-0.05
(alpha=2.52+-0.03) for the peak flux, alpha=1.79+-0.05 (alpha=2.47+-0.11) for
the fluence, and alpha=2.49+-0.11 (alpha=3.22+-0.15) for the duration. The
power-law indices for flares without CMEs are steeper than those for flares
with CMEs. The larger power-law index for flares without CMEs supports the
possibility that nanoflares contribute to coronal heating.


title: The FIR-Radio Relationship at High and Low Redshift

abstract:
  We use the results of the SCUBA Local Universe Galaxy Survey, a submillimetre
survey of galaxies in the nearby Universe, to investigate the relationship
between the far-infrared--submillimetre and radio emission of galaxies at both
low and high redshift. At low redshift we show that the correlation between
radio and far-infrared emission is much stronger than the correlation between
radio and submillimetre emission, which is evidence that massive stars are the
source of both the far-infrared and radio emission. At high redshift we show
that the submillimetre sources detected by SCUBA are brighter sources of radio
emission than are predicted from the properties of galaxies in the local
Universe. We discuss possible reasons for the cosmic evolution of the
relationship between radio and far-infrared emission.


title: Hibernation Revived by Weak Magnetic Braking

abstract:
  Cataclysmic variables undergo periodic nova explosions during which a finite
mass of material is expelled on a short timescale. The system widens and, as a
result, the mass-transfer rate drops. This state of hibernation may account for
the variety of cataclysmic variable types observed in systems of similar mass
and period. In the light of recent changes to the theory of nova ignition and
magnetic braking we investigate whether hibernation remains a viable mechanism
for creating cataclysmic variable diversity. We model the ratio of time spent
as dwarf novae (DNe) to nova-like systems (NLs). Above a critical mass-transfer
rate the system is NL and below it a DN. The dominant loss of angular momentum
is by magnetic braking but the rate is uncertain. It is also uncertain what
fraction of the mass accreted is expelled during the novae. We compare the
models of the ratios against the period of the system for different magnetic
braking rates and different ejected masses with the ratio of the number of
observed NLs to DNe. We deduce that a rate of angular momentum loss a factor of
ten smaller than that traditionally assumed is necessary if hibernation is to
account for the observed ratios.


title:
Constraints on RRAT Emission Mechanisms from RXTE/PCA Observations of
  RRAT J1819-1458

abstract:
  We derive the second and most stringent limit to date of the X-ray/radio flux
ratio (F_x/F_R) for the radio bursts associated with the recently identified
source class, the Rotating Radio Transients (RRATs). We analyze 20.1 hr of
\rxte/PCA observations of RRAT J1819-1458 -- a period during which 350\ppm23
RRAT radio bursts occurred, based on the previously observed average radio
burst rate. No X-ray bursts were detected, implying an upper-limit on the X-ray
flux for RRAT-bursts of <1.5e-8 ergs cm-2 s-1 (2-10 keV) or a luminosity
<2.3e37 (d/3.6\kpc)^2 ergs s-1. The time-average burst flux is <2e-13 ergs cm-2
s-1 (0.5-8 keV) -- a factor of 10 below that of the previously identified
persistent X-ray counterpart. Thus, X-ray bursts from the RRAT are
energetically unimportant compared with the persistent X-ray emission. From the
previously observed burst radio flux, we derive an upper-limit F_x/F_R< 4.2e-12
erg cm-2 s-1 mJy-1 for the radio bursts from this RRAT, the most stringent to
date, due to the high radio flux of bursts from this source. The F_x/F_R ratio
is a factor approximately 80 larger than that of the millisecond pulsar PSR
B1821-24; thus emission processes of X-ray/radio efficiency comparable to MSP
pulses cannot be ruled out. However, if the RRAT burst emission mechanism is
identical to the msec bursts of magnetars, then the msec bursts of magnetars
should be easily detected with radio instrumentation; yet none have been
reported to date.


title:
Relations Between the Luminosity, Mass, and Age Distributions of Young
  Star Clusters

abstract:
  We derive and interpret some relations between the luminosity, mass, and age
distributions of star clusters, denoted here by phi(L), psi(M), and chi(tau),
respectively. Of these, phi(L) is the easiest to determine observationally,
whereas psi(M) and chi(tau) are more informative about formation and disruption
processes. For populations of young clusters, with a relatively wide range of
ages, phi(L) depends on both psi(M) and chi(tau) and thus cannot serve as a
proxy for psi(M) in general. We demonstrate this explicitly by four
illustrative examples with specific forms for either psi(M) or chi(tau). In the
special case in which psi(M) is a power law and is independent of chi(tau),
however, phi(L) is also a power law with the same exponent as psi(M). We
conclude that this accounts for the observed similarity between phi(L) and
psi(M) for the young clusters in the Antennae galaxies. This result reinforces
our picture in which clusters form with psi(M) propto M^{-2} and are then
disrupted rapidly at a rate roughly independent of their masses. The most
likely disruptive process in this first stage is the removal of interstellar
matter by the energy and momentum input from young stars (by photoionization,
winds, jets, and supernovae). The few clusters that avoid this "infant
mortality" are eventually disrupted in a second stage by the evaporation of
stars driven by two-body relaxation, a process with a strong dependence on
mass. We suspect this picture may apply to many, if not all, populations of
star clusters, but this needs to be verified observationally by determinations
of psi(M) and chi(tau) in more galaxies.


title:
Equidistant frequency triplets in pulsating stars: The Combination Mode
  Hypothesis

abstract:
  Multiplet structures are a common feature in pulsating stars, and can be the
consequence of rotational splitting, mode interaction or sinusoidal amplitude
variations. In this paper we examine the phenomenon of (nearly) equidistant
triplets, which are unlikely to be caused by rotational splitting, in different
types of pulsating stars: a Delta Scuti variable (1 Mon), an RR Lyrae variable
(RR Lyr) and a short-period Cepheid (V743 Lyr). We examine the hypothesis that
one of the modes forming the triplet results from a combination of the other
two modes. The analyses were carried out on recent data sets by using
multiple-frequency analyses and statistics with the package PERIOD04. In
particular, the small departures from equidistance were calculated for the
three selected stars. For the Delta Scuti variable 1 Mon, the departure from
equidistance is only 0.000079 +- 0.000001 c/d (or 0.91 +- 0.01 nHz). For 1 Mon
the Combination Mode Hypothesis with a mode excited by resonance is the most
probable explanation. For the star RR Lyr, the hypothesis of resonance through
a combination of modes should be considered. The results for the best-studied
cepheid with a Blazhko period (V743 Lyr) are inconclusive because of an
unfavorable period of 1.49d and insufficient data.


title:
Dynamical Mass Estimates for Incomplete Orbits: Young Multiple Stars in
  Taurus and Ophiuchus

abstract:
  We present recent measurements of the orbital motion in the binaries, DF Tau
and ZZ Tau, and in the triples, Elias 12, T Tau, and V853 Oph. We observed
these systems with the Fine Guidance Sensors on the Hubble Space Telescope and
with adaptive optics imaging at the W. M. Keck and Gemini North Observatories.
Based on our measurements and those presented in the literature, we perform
preliminary orbital analyses for DF Tau, ZZ Tau, Elias 12 Na-Nb, and T Tau
Sa-Sb. Because the orbital coverage in most of these systems does not yet span
a sufficient portion of the orbit, we are not able to find definitive orbit
solutions. By using a Monte Carlo search technique, we explored the orbital
parameter space allowed by the current set of data available for each binary.
We constructed weighted distributions for the total mass of the binaries
derived from a large sample of possible orbits that fit the data. These mass
distributions show that the total mass is already well-defined. We compute
total mass estimates of 0.78 (+0.25/-0.15) Msun, 0.66 (+0.15/-0.11) Msun, 1.13
(+0.36/-0.09) Msun, and 4.13 (+1.58/-0.97) Msun for DF Tau, ZZ Tau, Elias 12
Na-Nb, and T Tau Sa-Sb respectively, using a distance of 140 pc. For Elias 12
Na-Nb, where the orbital coverage spans ~ 164 deg, we compute a preliminary
orbit solution with a period of ~ 9-12 years. By including an earlier lunar
occultation measurement, we also find a likely orbit solution for ZZ Tau, with
a period of ~ 32 years. With additional measurements to continue mapping the
orbits, the derived dynamical masses will be useful in constraining the
theoretical tracks of pre-main sequence evolution.


title: 3C 216: A Powerful FRII Seyfert 1 Galaxy

abstract:
  3C 216 has a weak accretion flow luminosity, well below the Seyfert1/QSO
dividing line, weak broad emission lines (BELs) and powerful radio lobes. As a
consequence of the extreme properties of 3C 216, it is the most convincing
example known of an FR II radio source that is kinetically dominated: the jet
kinetic luminosity, $Q$, is larger than the total thermal luminosity (IR to
X-ray) of the accretion flow, $L_{bol}$. Using three independent estimators for
the central black hole mass, we find that the jet in 3C 216 is very
super-Eddington, $3.3 L_{Edd}<\bar{Q}< 10 L_{Edd}$, where $\bar{Q}$ is the long
term time averaged $Q(t)$, calculated at 151 MHz. It is argued that 3C 216
satisfies the contemporaneous kinetically dominated condition, $R(t)\equiv
Q(t)/L_{bol}(t)>1$, either presently or in the past based on the rarity of
$L_{bol}>L_{Edd}$ quasars. The existence of $R(t)>1$ AGN is a strong constraint
on the theory of the central engine of FRII radio sources.


title:
Nonthermal Hard X-ray Emission and Iron Kalpha Emission from a
  Superflare on II Pegasi

abstract:
  We report on an X-ray flare detected on the active binary system II~Pegasi
with the Swift telescope. The trigger had a 10-200 keV luminosity of
2.2$\times10^{32}$ erg s$^{-1}$-- a superflare, by comparison with energies of
typical stellar flares on active binary systems. The trigger spectrum indicates
a hot thermal plasma with T$\sim$180 $\times10^{6}$K. X-ray spectral analysis
from 0.8--200 keV with the X-Ray Telescope and BAT in the next two orbits
reveals evidence for a thermal component (T$>$80 $\times10^{6}$K) and Fe K 6.4
keV emission. A tail of emission out to 200 keV can be fit with either an
extremely high temperature thermal plasma (T$\sim3\times10^{8}$K) or power-law
emission. Based on analogies with solar flares, we attribute the excess
continuum emission to nonthermal thick-target bremsstrahlung emission from a
population of accelerated electrons. We estimate the radiated energy from
0.01--200 keV to be $\sim6\times10^{36}$ erg, the total radiated energy over
all wavelengths $\sim10^{38}$ erg, the energy in nonthermal electrons above 20
keV $\sim3\times10^{40}$ erg, and conducted energy $<5\times10^{43}$ erg. The
nonthermal interpretation gives a reasonable value for the total energy in
electrons $>$ 20 keV when compared to the upper and lower bounds on the thermal
energy content of the flare. This marks the first occasion in which evidence
exists for nonthermal hard X-ray emission from a stellar flare. We investigate
the emission mechanism responsible for producing the 6.4 keV feature, and find
that collisional ionization from nonthermal electrons appears to be more
plausible than the photoionization mechanism usually invoked on the Sun and
pre-main sequence stars.


title: SCUBA Mapping of Spitzer c2d Small Clouds and Cores

abstract:
  We present submillimeter observations of dark clouds that are part of the
Spitzer Legacy Program, From Molecular Cores to Planet-Forming Disks (c2d). We
used the Submillimetre Common User's Bolometer Array to map the regions
observed by Spitzer by the c2d program to create a census of dense molecular
cores including data from the infrared to the submillimeter. In this paper, we
present the basic data from these observations: maps, fluxes, and source
attributes. We also show data for an object just outside the Perseus cloud that
was serendipitously observed in our program. We propose that this object is a
newly discovered, evolved protostar.


title:
Astronomical Science with Laser Guide Star Adaptive Optics: A Brief
  Review, a Current Snapshot, and a Bright Future

abstract:
  We briefly discuss the past, present, and future state of astronomical
science with laser guide star adaptive optics (LGS AO). We present a tabulation
of refereed science papers from LGS AO, amounting to a total of 23 publications
as of May 2006. The first decade of LGS AO science (1995-2004) was marked by
modest science productivity (~1 paper/year), as LGS systems were being
implemented and commissioned. The last two years have seen explosive science
growth (~1 paper/month), largely due to the new LGS system on the Keck II
10-meter telescope, and point to an exciting new era for high angular
resolution science. To illustrate the achievable on-sky performance, we present
an extensive collection of Keck LGS performance measurements from the first
year of our brown dwarf near-IR imaging survey. We summarize the current
strengths and weaknesses of LGS compared to Hubble Space Telescope, offer a
list of desired improvements, and look forward to a bright future for LGS given
its wide-scale implementation on large ground-based telescopes.


title: Pair-Production Supernovae: Theory and Observation

abstract:
  I review the physical properties of pair-production supernovae (PPSNe) as
well as the prospects for them to be constrained observationally. In very
massive (140-260 solar mass) stars, much of the pressure support comes from the
radiation field, meaning that they are loosely bound, with an adiabatic
coefficient that is close to the minimum stable value. Near the end of C/O
burning, the central temperature increases to the point that photons begin to
be converted into electron-positron pairs, softening gamma below this critical
value. The result is a runaway collapse, followed by explosive burning that
completely obliterates the star. While these explosions can be up to 100 times
more energetic that core collapse and Type Ia supernovae, their peak
luminosities are only slightly greater. However, due both to copious Ni-56
production and hydrogen recombination, they are brighter much longer, and
remain observable for ~ 1 year. Since metal enrichment is a local process,
PPSNe should occur in pockets of metal-free gas over a broad range of
redshifts, greatly enhancing their detectability, and distributing their
nucleosyntehtic products about the Milky Way. This means that measurements of
the abundances of metal-free stars should be thought of as directly
constraining these objects. It also means that ongoing supernova searches,
already provide weak constraints for PPSN models. A survey with the NIRCam
instrument on JWST, on the other hand, would be able to extend these limits to
z ~ 10. Observing a 0.3 deg^2 patch of sky for one week per year for three
consecutive years, such a program would either detect or rule out the existence
of these remarkable objects.


title:
Properties of RR Lyrae stars in the inner regions of the Large
  Magellanic Cloud. II. The extended sample

abstract:
  All galaxies that have been adequately examined so far have shown an extended
stellar halo. To search for such a halo in the LMC we have obtained
low-resolution spectra for 100 LMC RR Lyrae stars, of which 87 are in the field
and 13 in the clusters NGC1835 and NGC2019. We measured radial velocities for
87 LMC RR Lyrae stars, and metallicities for 78 RR Lyrae stars, nearly tripling
the previous sample. These targets are located in 10 fields covering a wide
range of distances, out to 2.5 degrees from the center of the LMC. Our main
result is that the mean velocity dispersion for the LMC RR Lyrae stars is
50+-2km/s. This quantity does not appear to vary with distance from the LMC
center. The metallicity shows a Gaussian distribution, with mean
[Fe/H]=-1.53+-0.02dex, and dispersion 0.20 dex in the Harris metallicity scale,
confirming that they represent a very homogeneous metal-poor population. There
is no dependence between the kinematics and metallicity of the field RR Lyrae
star population. Using good quality low-resolution spectra from FORS1, FORS2
and GEMINI-GMOS we have found that field RR Lyrae stars in the LMC show a large
velocity dispersion and that this indicate the presence of old and metal-poor
stellar halo. All the evidence so far for the halo, however, is from the
spectroscopy of the inner LMC regions, similar to the inner flattened halo in
our Galaxy. Further study is necessary to confirm this important result.


title: High Resolution Radio Maps of Four Nearby Spiral Galaxies

abstract:
  We report subarcsecond-resolution VLA imaging of the centers of four nearby
spiral galaxies: IC 342, Maffei II, NGC 2903, and NGC 6946. In each galaxy, 7 -
12 compact radio continuum sources were identified within the central 15" x
15". Slightly over half of the compact sources appear to be HII regions with
flat or positive spectral indices (alpha >~ -0.1). The HII regions with rising
spectra are optically thick at centimeter wavelengths, and thus dense (n_i ~
10^4 cm^(-3)) and young. The largest of these HII regions require the
excitation of 500 - 800 O stars, within regions of only few parsecs extent.
These clusters approach the sizes expected for globular clusters.


title:
Virgo's Intracluster Globular Clusters as Seen by the Advanced Camera
  for Surveys

abstract:
  We report the discovery of 4 candidate intracluster globular clusters (IGCs)
in a single deep HST ACS field of the Virgo Cluster. We show that each cluster
is roughly spherical, has a magnitude near the peak of the Virgo globular
cluster luminosity function, has a radial profile that is best-fit by a King
model, and is surrounded by an excess of point sources which have the colors
and magnitudes of cluster red giant stars. Despite the fact that two of our IGC
candidates have integrated colors redder than the mean of the M87 globular
cluster system, we propose that all of the objects are metal-poor with [M/H] <
-1. We show that the tidal radii of our intracluster globulars are all larger
than the mean for Milky Way clusters, and suggest that the clusters have
undergone less tidal stress than their Galactic counterparts. Finally, we
normalize our globular cluster observations to the luminosity of intracluster
stars, and derive a value of S_N ~ 6 for the specific frequency of Virgo
intracluster globular clusters. We use these data to constrain the origins of
Virgo's intracluster population, and suggest that globular clusters in our
intracluster field have a different origin than globular clusters in the
vicinity of M87. In particular, we argue that dwarf elliptical galaxies may be
an important source of intracluster stars.


title: Subarcsecond-Resolution Radio Maps of Nearby Spiral Galaxies

abstract:
  We report subarcsecond-resolution VLA imaging of four nearby spiral galaxies:
IC 342, Maffei II, NGC 2903, and NGC 6946. In each galaxy, compact radio
continuum sources are identified in the central ~ 15" x 15" region. These
compact sources are responsible for 20 - 30 % of the total emission from the
central kpc of the host galaxies at 2 cm, but only ~ 5 - 10 % at 6 cm. More
than half of the compact sources appear to be HII regions. The HII regions with
rising spectra must be fairly dense (n_i ~ 10^4 cm^(-3)) and are presumably
very young. The largest of these HII regions require the excitation of 500 -
800 O stars, within regions of only few parsecs extent. These clusters approach
the sizes expected for globular clusters. Thermal free-free emission from
compact sources contributes more significantly at 2 cm, while diffuse
synchrotron emission dominates at 6 cm. The radio HII regions are found near
the centers of giant molecular clouds in projection, and do not have obvious
visual counterparts.


title: The Ionization State of Sodium in Galactic Winds

abstract:
  Roughly 80% of Ultraluminous Infrared Galaxies (ULIRGs) show blue shifted
absorption in the resonance lines of neutral sodium, indicating that cool winds
are common in such objects, as shown by Rupke et al and by Martin. The neutral
sodium (NaI) columns indicated by these absorption lines are ~
10^{13}-3x10^{14}/cm^2, while the bolometric luminosity varies by a factor of
only four. We show that the gas in ULIRG outflows is likely to be in
photoionization equilibrium. The very small ULIRG sample of Goldader et al.
demonstrates that the ratio of ultraviolet flux to far infrared flux varies by
a factor $\sim100$ from object to object. While the Goldader sample does not
overlap with those of Rupke et al. and Martin, we show that such a large
variation in ultraviolet flux will produce a similar variation in the column of
neutral sodium for a fixed mass flux and density. However, if the cold gas is
in pressure equilibrium with a hot outflow with a mass loss rate similar to the
star formation rate, the range of ionization state is significantly smaller.
Measurements of the UV flux for objects in the Martin and Rupke et al. catalogs
will definitively determine if photoionization effects are responsible for the
wide variation seen in the sodium columns. If they are, a determination of the
gas density and mass loss rate in the cool winds will follow, with attendant
improvements in our understanding of wind driving mechanisms and of the effects
of galaxies on their surroundings.


title:
Development of Large area Gamma-ray Camera with GSO(Ce) Scintillator
  Arrays and PSPMTs

abstract:
  We have developed a position-sensitive scintillation camera with a large area
absorber for use as an advanced Compton gamma-ray camera. At first we tested
GSO(Ce) crystals. We compared light output from the GSO(Ce) crystals under
various conditions: the method of surface polishing, the concentration of Ce,
and co-doping Zr. As a result, we chose the GSO(Ce) crystals doped with only
0.5 mol% Ce, and its surface polished by chemical etching as the scintillator
of our camera. We also made a 16$\times$16 cm$^2$ scintillation camera which
consisted of 9 position-sensitive PMTs (PSPMTs Hamamatsu flat-panel H8500), the
each of which had 8$\times$8 anodes with a pitch of 6 mm and coupled to
8$\times$8 arrays of pixelated 6$\times6\times$13 mm$^3$ GSO(Ce) scintillators.
For the readout system of the 576 anodes of the PMTs, we used chained resistors
to reduce the number of readout channels down to 48 to reduce power
consumption. The camera has a position resolution of less than 6mm and a
typical energy resolution of 10.5% (FWHM) at 662 keV at each pixel in a large
area of 16$\times$16 cm$^2$. %to choose the best scintillator for our project.
  Furthermore we constructed a 16$\times$16 array of 3$\times3\times$13 mm$^3$
pixelated GSO(Ce) scintillators, and glued it to a PMT H8500. This camera had
the position resolution of less than 3mm, over an area of 5$\times$5 cm$^2$,
except for some of the edge pixels; the energy resolution was typically 13%
(FWHM) at 662 keV.


title:
Iron and Nickel Line Diagnostics for the Galactic Center Diffuse
  Emission

abstract:
  We have observed the diffuse X-ray emission from the Galactic center (GC)
using the X-ray Imaging Spectrometer (XIS) on Suzaku. The high-energy
resolution and the low-background orbit provide excellent spectra of the GC
diffuse X-rays (GCDX). The XIS found many emission lines in the GCDX near the
energy of K-shell transitions of iron and nickel. The most pronounced features
are FeI K alpha at 6.4 keV and K-shell absorption edge at 7.1 keV, which are
from neutral and/or low ionization states of iron, and the K-shell lines at 6.7
keV and 6.9 keV from He-like (FeXXV K alpha) and hydrogenic (FeXXVI Ly alpha)
ions of iron. In addition, K alpha lines from neutral or low ionization nickel
(NiI K alpha) and He-like nickel (NiXXVII K alpha), and FeI K beta, FeXXV K
beta, FeXXVI Ly beta, FeXXV K gamma and FeXXVI Ly gamma are detected for the
first time. The line center energies and widths of FeXXV K alpha and FeXXVI Ly
alpha favor a collisional excitation (CE) plasma for the origin of the GCDX.
The electron temperature determined from the line flux ratio of FeXXV K alpha /
FeXXV K beta is similar to the ionization temperature determined from that of
FeXXV K alpha /FeXXVI Ly alpha. Thus it would appear that the GCDX plasma is
close to ionization equilibrium. The 6.7 keV flux and temperature distribution
to the galactic longitude is smooth and monotonic,in contrast to the integrated
point source flux distribution. These facts support the hypothesis that the
GCDX is truly diffuse emission rather than the integration of the outputs of a
large number of unresolved point sources. In addition, our results demonstrate
that the chemical composition of Fe in the interstellar gas near the GC is
constrained to be about 3.5 times solar.


title: Cosmic Magnetic Fields and the CMB

abstract:
  I describe the imprint of primordial magnetic fields on the CMB. I show that
these are observable only if the field amplitude is of the order of $B\gsim
10^{-9}G$ on Mpc scale. I further argue that such fields are strongly
constrained by the stochastic background of gravity waves which they produce.
Primordial magnetic fields, which are strong enough to be seen in the CMB, are
compatible with the nucleosynthesis bound, only if their spectrum is close to
scale invariant, or maybe if helical magnetic fields provoke an inverse
cascade. For helical fields, the CMB signature is especially interesting. It
contains parity violating T-B and E--B correlations.


title: New X-ray views of the Galactic center observed with Suzaku

abstract:
  We report the diffuse X-ray emissions from the Sgr A and B regions observed
with Suzaku. From the Sgr A region, we found many K-shell transition lines of
iron and nickel. The brightest are K alpha lines from FeI, FeXXV and FeXXVI at
6.4 keV, 6.7 keV and 6.9 keV. In addition, K alpha lines of NiI and NiXXVII, K
beta of FeI, FeXXV and FeXXVI, and K gamma of FeXXV and FeXXVI are detected for
the first time. The center energy of K alpha of FeXXV favors collisional
excitation as the origin for this line emission. The ionization temperature
determined from the flux ratio of K alpha of FeXXV and FeXXVI is similar to the
electron temperature determined from the flux ratio of K alpha and K beta of
FeXXV, which are in the range of 5-7 keV. Consequently, the Galactic Center
diffuse X-rays (GCDX) are consistent with emission from a plasma nearly in
ionization equilibrium. The radio complex Sgr B region also exhibits K alpha
lines of FeI, FeXXV and FeXXVI. The 6.7 keV line (FeXXV) map exhibits a local
excess at (l,b) = (0.612, 0.01), and could be a new young SNR. The 6.4 keV
image is clumpy with local excesses near Sgr B2 and at (l,b) = (0.74, -0.09).
Like Sgr B2, this latter excess may be another X-ray reflection Nebulae (XRN).


title: Dark energy rest frame and the CMB dipole

abstract:
  If dark energy can be described as a perfect fluid, then, apart from its
equation of state relating energy density and pressure, we should also especify
the corresponding rest frame. Since dark energy is typically decoupled from the
rest of components of the universe, in principle such a frame could be
different from that of matter and radiation. In this work we consider the
potential observable effects of the motion of dark energy and the possibility
to measure the dark energy velocity relative to matter. In particular we
consider the modification of the usual interpretation of the CMB dipole and its
implications for the determination of matter bulk flows on very large scales.
We also comment on the possible origin of a dark energy flow and its evolution
in different models.


title:
Potential of Ozone Formation by the Smog Mechanism to shield the surface
  of the Early Earth from UV radiation?

abstract:
  We propose that the photochemical smog mechanism produced substantial ozone
(O3) in the troposphere during the Proterozoic, which contributed to
ultraviolet (UV) radiation shielding hence favoured the establishment of life.
The smog mechanism is well-established and is associated with pollution hazes
which sometimes cover modern cities. The mechanism proceeds via the oxidation
of volatile organic compounds (VOCs) such as methane (CH4) in the presence of
UV radiation and nitrogen oxides (NOx). It would have been particularly
favoured during the Proterozoic given the high levels of CH4 (up to 1000 ppm)
recently suggested. Proterozoic UV levels on the surface of the Earth were
generally higher compared with today, which would also have favoured the
mechanism. On the other hand, Proterozoic O2 required in the final step of the
smog mechanism to form O3 was less abundant compared with present times.
Further, results are sensitive to Proterozoic NOx concentrations, which are
challenging to predict, since they depend on uncertain quantities such as NOx
source emissions and OH concentrations. We review NOx sources during the
Proterozoic and apply a photochemical box model having methane oxidation with
NOx, HOx and Ox chemistry to estimate the O3 production from the smog
mechanism. Runs suggest the smog mechanism during the Proterozoic can produce
about double present day ozone columns for NOx levels of 1.53 10-9 by volume
mixing ratio, which was attainable according to our NOx source analysis, with 1
per-cent present atmospheric levels (PALs) of O2. Clearly, forming ozone in the
troposphere is a trade-off for survivability. On the one hand harmful UV is
blocked, but on the other hand ozone is a respiratory irratant, which becomes
fatal at concentrations exceeding about 1 ppmv.


title:
The radial distribution of blue straggler stars and the nature of their
  progenitors

abstract:
  The origin of blue straggler stars (BSS) in globular clusters (GCs) is still
not fully understood: they can form from stellar collisions, or through mass
transfer in isolated, primordial binaries (PBs). In this paper we use the
radial distribution of BSS observed in four GCs (M3, 47Tuc, NGC6752 and omega
Cen) to investigate which formation process prevails. We find that both
channels co-exist in all the considered GCs. The fraction of mass-transfer
(collisional) BSS with respect to the total number of BSS is around ~0.4-0.5
(~0.5-0.6) in M3, 47Tuc, and NGC6752. The case of omega Cen is peculiar with an
underproduction of collisional BSS. The relative lack of collisional BSS in
omega Cen can be understood if mass segregation has not yet driven to the core
a sizeable number of PBs, which dominate stellar collisions through three- and
four-body processes. The spatial distribution of BSS provides strong hints to
their origin: the BSS in the cluster outskirts form almost exclusively from
mass transfer in PBs, whereas the BSS found close to the cluster core most
likely have a collisional origin.


title:
The ultra-compact binary 4U1850-087 observed with INTEGRAL: hard X-ray
  emission from an X-ray burster

abstract:
  The X-ray burster 4U1850-087, located in the Galactic globular cluster
NGC6712, is an ultracompact binary (orbital period~21 min),likely harbouring a
degenerate companion.The source has been observed at soft gamma-rays several
times with the INTEGRAL satellite,during the monitoring of the Galactic plane,
with an unprecedented exposure time.We analysed all available INTEGRAL
observations, with the main aim of studying the long-term behaviour of this
Galactic bulge X-ray burster.The spectral results are based on the systematic
analysis of all INTEGRAL observations covering the source position performed
between March 2003 and November 2005.The source X-ray emission is hard and is
observed, for the first time, up to 100keV.A broad-band spectrum obtained
combining the INTEGRAL spectrum together with a quasi-simultaneous XMM-Newton
observation performed in September 2003 is well modeled with a disk-blackbody
emission (with kTin=0.8keV) together with a power-law (photon index=2.1).The
2-100keV luminosity is 1.5E36 erg/s (assuming a distance of 6.8kpc).


title: Class I methanol masers in the outflow of IRAS 16547-4247

abstract:
  The Australia Telescope Compact Array (ATCA) has been used to image class I
methanol masers at 9.9, 25 (a series from J=2 to J=9), 84, 95 and 104 GHz
located in the vicinity of IRAS 16547-4247 (G343.12-0.06), a luminous young
stellar object known to harbour a radio jet. The detected maser emission
consists of a cluster of 6 spots spread over an area of 30 arcsec. Five spots
were detected in only the 84- and 95-GHz transitions (for two spots the 84-GHz
detection is marginal), while the sixth spot shows activity in all 12 observed
transitions. We report the first interferometric observations of the rare 9.9-
and 104-GHz masers. It is shown that the spectra contain a very narrow spike
(<0.03 km/s) and the brightness temperature in these two transitions exceeds
5.3x10^7 and 2.0x10^4 K, respectively. The three most southern maser spots show
a clear association with the shocked gas traced by the H_2 2.12 micron emission
associated with the radio jet and their velocities are close to that of the
molecular core within which the jet is embedded. This fact supports the idea
that the class I masers reside in the interface regions of outflows. Comparison
with OH masers and infrared data reveals a potential discrepancy in the
expected evolutionary state. The presence of the OH masers usually means that
the source is evolved, but the infrared data suggest otherwise. The lack of any
class II methanol maser emission at 6.7 GHz in the source raises an additional
question, is this source too young or too old to have a 6.7 GHz maser? We argue
that both cases are possible and suggest that the evolutionary stage where the
class I masers are active, may last longer and start earlier than when the
class II masers are active. However, it is currently not possible to reveal the
exact evolutionary status of IRAS 16547-4247.