title:
The Origin of the Large-Scale Structure in the Universe: Theoretical and
  Statistical Aspects

abstract:
  We review some theoretical and statistical aspects of the origin of the
large-scale structure in the Universe, in view of the two most widely known and
accepted scenarios: the inflaton and the curvaton scenarios. Among the
theoretical aspects, we point out the impossibility of having a low
inflationary energy scale in the simplest curvaton model. A couple of
modifications to the simplest setup are explored, corresponding to the
implementation of a second (thermal) inflationary period whose end makes the
curvaton field `heavy', triggering either its oscillations or immediate decay.
Low scale inflation is then possible to attain with H_\ast being as low as 1
TeV. Among the statistical aspects, we study the bispectrum
B_\zeta(k_1,k_2,k_3) of the primordial curvature perturbation \zeta whose
normalisation \fnl gives information about the level of non-gaussianity in
\zeta. In connection with \fnl, several conserved and/or gauge invariant
quantities described as the second-order curvature perturbation have been given
in the literature. We review each of these quantities showing how to interpret
one in terms of the others, and analyze the respective expected \fnl in both
the inflaton and the curvaton scenarios as well as in other less known models
for the generation of primordial perturbations and/or non-gaussianities. The
\delta N formalism turns out to be a powerful technique to compute \fnl in
multi-component slow-roll inflation, as the knowledge of the evolution of some
family of unperturbed universes is the only requirement. We present for the
first time this formalism and apply it to selected examples.


title:
On the role of injection in kinetic approaches to nonlinear particle
  acceleration at non relativistic shocks

abstract:
  The dynamical reaction of the particles accelerated at a shock front by the
first order Fermi process can be determined within kinetic models that account
for both the hydrodynamics of the shocked fluid and the transport of the
accelerated particles. These models predict the appearance of multiple
solutions, all physically allowed. We discuss here the role of injection in
selecting the {\it real} solution, in the framework of a simple
phenomenological recipe, which is a variation of what is sometimes referred to
as {\it thermal leakage}. In this context we show that multiple solutions
basically disappear and when they are present they are limited to rather
peculiar values of the parameters.


title: Spectroscopy of twelve Type Ia supernovae at intermediate redshift

abstract:
  We present spectra of twelve Type Ia supernovae obtained in 1999 at the
William Herschel Telescope and the Nordic Optical Telescope during a search for
Type Ia supernovae (SN Ia) at intermediate redshift. The spectra range from
z=0.178 to z=0.493, including five high signal-to-noise ratio SN Ia spectra in
the still largely unexplored range 0.15 < z < 0.3. Most of the spectra were
obtained before or around restframe B-band maximum light. None of them shows
the peculiar spectral features found in low-redshift over- or under-luminous SN
Ia. Expansion velocities of characteristic spectral absorption features such as
SiII at 6355 angs., SII at 5640 angs. and CaII at 3945 angs. are found
consistent with their low-z SN Ia counterparts.


title:
High-order 2MASS galaxy correlation functions: Probing the primordial
  density field and the linearity of galaxy bias

abstract:
  We use the 2MASS extended source catalogue to determine angular correlation
functions, w_p, to high orders (p<=9). The main sample contains 650,745
galaxies and represents an order of magnitude increase in solid angle over
previous samples used in such analysis. The high-order correlation functions
are used to determine the projected and real space hierarchical amplitudes, s_p
and S_p. In contrast to recent results, for p<=6 these parameters are found to
be quite constant over a wide range of scales to r=40 Mpc, consistent with a
Gaussian form to the primordial distribution of density fluctuations which has
evolved under the action of gravitational instability. We test the sensitivity
of our results to the presence of rare fluctuations in the local galaxy
distribution by cutting various regions of over-density from the main sample;
unlike previous analyses, we find that our results are relatively robust to the
removal of the largest superclusters. We use our constraints on the K-band S_p
parameters in two ways. First, we examine their consistency with non-Gaussian
initial conditions; we are able to rule out strong non-Gaussianity in the
primordial density field, as might be seeded by topological defects such as
cosmic strings or global textures at the 2.5 sigma confidence level. Second, we
investigate the way in which galaxies trace the underlying mass distribution.
We find evidence for a non-zero quadratic contribution to the galaxy bias,
parameterised by c_2=0.57+/-0.33. This positive result represents a significant
difference from the negative values found previously; we examine a possible
explanation in the light of recent observations which universally provide
negative values for c_2.


title: A Spitzer/IRAC Survey of Massive Star-Forming Regions

abstract:
  We are conducting a survey of several regions of high-mass star formation to
assess their content and structure. The observations include Spitzer
observations, ground-based optical and near-IR imaging surveys, and optical and
IR spectra of objects and locations in the molecular clouds. The goal of the
survey is to gain a better understanding of the processes involved in high mass
star formation by determining the characteristics of the stars detected in
these regions and investigating the properties of the interstellar medium (ISM)
environment in which these stars form. In this contribution, we present results
on the identification and spatial analysis of young stars in three clusters,
W5/AFGL 4029, S255, and S235. First we show how the IRAC data are used to
roughly segregate young stars according to their mid-infrared colors, into two
groups corresponding the SED Class I and Class II young stellar objects. Then
using the IRAC data in combination with 2MASS, we show how more young stars can
be identified. Finally, we examine the spatial distributions of young stars in
these clusters and find a range of morphologies and of peak surface densities.


title:
STIS Spectroscopy of Young Star Clusters in "The Antennae" Galaxies (NGC
  4038/4039)

abstract:
  Long-slit spectra of several dozen young star clusters have been obtained at
three positions in the Antennae galaxies with the Space Telescope Imaging
Spectrograph (STIS) and its 52"x0.2" slit. Based on H-alpha emission-line
measurements, the average cluster-to-cluster velocity dispersion in 7 different
cluster aggregates ("knots") is <10 \kms. The fact that this upper limit is
similar to the velocity dispersion of gas in the disks of typical spiral
galaxies suggests that the triggering mechanism for the formation of young
massive compact clusters ("super star clusters") is unlikely to be high
velocity cloud-cloud collisions. On the other hand, models where preexisting
giant molecular clouds in the disks of spiral galaxies are triggered into
cluster formation are compatible with the observed low velocity dispersions.
These conclusions are consistent with those reached by Zhang et al. (2001)
based on comparisons between the positions of the clusters and the velocity and
density structure of the nearby interstellar medium. We find evidence for
systematically lower values of the line ratios [NII]/H-alpha and [SII]/H-alpha
in the bright central regions of some of the knots, relative to their outer
regions. This suggests that the harder ionizing photons are used up in the
regions nearest the clusters, and the diffuse ionized gas farther out is
photoionized by 'leakage' of the leftover low-energy photons. The low values of
the [SII]/H-alpha line ratio, typically [SII]/H-alpha<0.4, indicates that the
emission regions are photoionized rather than shock heated. The absence of
evidence for shock-heated gas is an additional indication that high velocity
cloud-cloud collisions are not playing a major role in the formation of the
young clusters.


title: Soft gamma-ray background and light Dark Matter annihilation

abstract:
  The bulk of the extragalactic background between 10 keV and 10 GeV is likely
to be explained by the emission of Seyfert galaxies, type Ia supernovae, and
blazars. However, as revealed by the INTEGRAL satellite, the bulge of our
galaxy is an intense source of a 511 keV gamma-ray line, indicating the
production of a large number of positrons that annihilate. The origin of the
latter is debated, and they could be produced, in particular, by the (S- or
P-wave) annihilation of light Dark Matter particles into e+e-. In any case, the
cumulated effect of similar sources at all redshifts could lead to a new
background of hard X-ray and soft gamma-ray photons. On the basis of the
hierarchical model of galaxy formation, we compute analytically the SNIa
contribution to the background, and add it to Seyfert and blazars emission
models. We find that any extra contribution to this unresolved background at
511 keV should be lower than about 4 keV/cm^2/s/sr. We also estimate
analytically the extragalactic background due to Dark Matter annihilation,
increasing the accuracy of the earlier computations. Indeed, we take into
account the large positron escape fraction from low mass dark matter halos,
unable to confine a dense and magnetized interstellar medium. Our new
background estimate turns out to be one order of magnitude lower, so that the
hypothesis of a light Dark Matter candidate remains compatible with the
observed extragalactic background for a wider range of particle masses and
cross-sections.


title: The BeppoSAX catalog of GRB X-ray afterglow observations

abstract:
  We present the X-ray afterglow catalog of BeppoSAX from the launch of the
satellite to the end of the mission. Thirty-three X-ray afterglows were
securely identified based on their fading behavior out of 39 observations. We
have extracted the continuum parameters (decay index, spectral index, flux,
absorption) for all available afterglows. We point out a possible correlation
between the X-ray afterglow luminosity and the energy emitted during the prompt
$\gamma$-ray event. We do not detect a significant jet signature within the
afterglows, implying a lower limit on the beaming angle, neither a standard
energy release when X-ray fluxes are corrected for beaming. Our data support
the hypothesis that the burst should be surrounded by an interstellar medium
rather than a wind environment, and that this environment should be dense. This
may be explained by a termination shock located near the burst progenitor. We
finally point out that some dark bursts may be explained by an intrinsic
faintness of the event, while others may be strongly absorbed.


title: The Baikal neutrino experiment: from NT200 to NT200+

abstract:
  The Baikal neutrino telescope NT200 takes data since 1998. In 2005, the
deployment of three additional strings for common operation with NT200 was
finished. We describe the physics program and the design of the new telescope
named NT200+ and present selected physical results obtained with NT200. First
results from NT200+ will be presented at the conference.


title:
X-ray continuum properties of GRB afterglows observed by XMM-Newton and
  Chandra

abstract:
  We present a catalog of XMM-Newton and Chandra observations of gamma-ray
burst (GRB) afterglows, reduced in a common way using the most up-to-date
calibration files and software. We focus on the continuum properties of the
afterglows. We derive the spectral and temporal decay indices for 16 bursts. We
place constraints on the burst environment and geometry. A comparison of the
fast XMM-Newton follow-up and the late Chandra observations shows a significant
difference in those parameters, likely produced by a transition from jet
expansion taking place between two and ten days after the burst. We do not
observe a significant shrinking of the luminosity distribution when we correct
for beaming; more burst observations are needed to confirm this result. We also
compare our results with those obtained by BeppoSAX and SWIFT; there is no
strong discrepancy between the afterglow fluxes observed with these satellites
when we carefully take into account the different median observation time of
each observatory.


title: The Fourth Data Release of the Sloan Digital Sky Survey

abstract:
  This paper describes the fourth data release of the Sloan Digital Sky Survey
(SDSS), including all survey-quality data taken through June 2004. The data
release includes five-band photometric data for 180 million objects selected
over 6670 deg^2, and 673,280 spectra of galaxies, quasars, and stars selected
from 4783 deg^2 of that imaging data using the standard SDSS target selection
algorithms. These numbers represent a roughly 25% increment over those of the
Third Data Release. The Fourth Data Release also includes an additional 131,840
spectra of objects selected using a variety of alternative algorithms, to
address scientific issues ranging from the kinematics of stars in the Milky Way
thick disk to populations of faint galaxies and quasars.


title:
Search for a diffuse flux of high-energy neutrinos with the NT200
  neutrino telescope

abstract:
  We present the results of a search for high energy extraterrestrial neutrinos
with the Baikal underwater Cherenkov detector NT200, based on data taken in
1998 - 2002 (1038 live days).Upper limits on the diffuse fluxes of
\nu_e+\nu_{\mu}+\nu_{\tau}, predicted by several models of AGN-like neutrino
sources, are derived. For an E^{-2} behavior of the neutrino spectrum, our
limit is E^2 \Phi_{\nu}(E)<8.1 10^{-7} cm^{-2} s^{-1} sr^{-1} GeV over a
neutrino energy range 2 10^4 - 5 10^7 GeV covering 90% of expected events. The
upper limit on the resonant \bar{\nu}_e diffuse flux is \Phi_{\bar{\nu}_e} <
3.3 10^{-20} cm^{-2}s^{-1}sr^{-1}GeV^{-1}.


title:
Search for relativistic magnetic monopoles with the Baikal neutrino
  telescope NT200

abstract:
  We present a limit on the flux of relativistic monopoles obtained during 994
days of operation of the Baikal neutrino telescope NT200. The search for
relativistic monopoles is based on the enormous amount of Cherenkov radiation
emitted by these particles.


title:
Holographic cosmic energy, fundamental physics and the future of the
  universe

abstract:
  Holographic dark energy models have been recently suggested which most
clearly show that accelerating cosmology appears to be incompatible with
mathematically consistent formulations of fundamental theories such as string/M
theories. In this paper it is however argued that holographic phantom models
are no longer incompatible with such theories, provided that we allow for the
existence of wormholes and ringholes near the big rip singularity and a
quantization condition on the parameter of the equation of state is introduced.
It is also seen that such a condition actually implies a quantization of the
phantom energy which stabilizes the fluid against decay processes.


title:
Baikal neutrino telescope NT200+ : Upgrade of data acquisition and time
  calibration systems

abstract:
  The Baikal neutrino telescope NT200, operating since 1998, has been upgraded
in spring 2005 to NT200+. This telescope with 3 additional outer strings at 100
m radius from the center encloses a geometric volume of 5 Mtons. We describe
the modernized data acquisition and control system, which allows for higher
bandwidth, full multiplexing of data and control streams over a single cable to
shore, redundant system components and underwater data pre-processing. To
calibrate all time offsets between new distant strings and the central
telescope on the nsec-scale, a new external laser unit with a powerful N2-Dye
laser and a light diffusor, has been developed. This laser is also used to tune
reconstruction techniques for pointlike showers with energies from 20 TeV to 10
PeV.


title:
A multi-frequency study of the spectral index distribution in the SNR
  CTB 80

abstract:
  We have conducted a study at radio wavelengths of the spectral behaviour of
the supernova remnant (SNR) CTB 80. Based on an homogenised data set of
integrated flux densities, we calculated for the whole SNR a radio index -0.36
+/- 0.02. The shape of the global spectrum suggests absorption by ionized gas
in the interstellar medium (ISM) along the line of sight. Spatial spectral
variations across the SNR are investigated based on high-angular resolution
data at 240, 324, 610, and 1380 MHz using different techniques. The three
extended arms associated with this SNR, show a clear indication of spectral
steepening when moving outwards from the central nebula, with variations of up
to - 0.9. However, while the spectral steepening is smooth along the eastern
arm, the northern and soutwestern arms include locally flatter structures,
which in all cases coincide with radio, IR, and optical emission enhancements.
We interpret this spectral property as the result of the combination of two
different particle populations: aging relativistic electrons injected by PSR
B1951+32 and particles accelerated at the sites where the SNR shock front
encounters interstellar gas inhomogeneities. Concerning the central nebula, the
angular resolution of the available database does not permit a detailed
spectral study of the core region, i.e. the 45'' region around PSR B1951+32,
where we can only confirm an average spectral index alpha=0.0. The surrounding
8' plateau nebula has an <alpha> ~ -0.25, with a peak of alpha ~ -0.29
coincident with a secondary maximun located at the termination of a twisted
filament that trails to the east, behind the pulsar.


title: Generalizing the generalized Chaplygin gas

abstract:
  The generalized Chaplygin gas is characterized by the equation of state p = -
A/rho^alpha, with alpha > -1 and w > -1. We generalize this model to allow for
the cases where alpha < -1 or w < -1. This generalization leads to three new
versions of the generalized Chaplygin gas: an early phantom model in which w <<
-1 at early times and asymptotically approaches w = -1 at late times, a late
phantom model with w \approx -1 at early times and w -> - \infty at late times,
and a transient model with w \approx -1 at early times and w -> 0 at late
times. We consider these three cases as models for dark energy alone and
examine constraints from type Ia supernovae and from the subhorizon growth of
density perturbations. The transient Chaplygin gas model provides a possible
mechanism to allow for a currently accelerating universe without a future
horizon, while some of the early phantom models produce w < -1 without either
past or future singularities.


title:
A Statistical Study of Threshold Rotation Rates for the Formation of
  Disks around Be Stars

abstract:
  This paper presents a detailed statistical determination of the equatorial
rotation rates of classical Be stars. The rapid rotation of Be stars is likely
to be linked to the ejection of gas that forms dense circumstellar disks. The
physical origins of these disks are not understood, though it is generally
believed that the ability to spin up matter into a Keplerian disk depends on
how close the stellar rotation speed is to the critical speed at which the
centrifugal force cancels gravity. There has been recent disagreement between
the traditional idea that Be stars rotate between 50 and 80 percent of their
critical speeds and new ideas (inspired by the tendency for gravity darkening
to mask rapid rotation at the equator) that their rotation may be very nearly
critical. This paper utilizes Monte Carlo forward modeling to simulate
distributions of the projected rotation speed (v sin i), taking into account
gravity darkening, limb darkening, and observational uncertainties. A
chi-squared minimization procedure was used to find the distribution parameters
that best reproduce observed v sin i distributions from R. Yudin's database.
Early-type (O7e-B2e) Be stars were found to exhibit a roughly uniform spread of
intrinsic rotation speed that extends from 40 to 60 percent up to 100 percent
of critical. Late-type (B3e-A0e) Be stars exhibit progressively narrower ranges
of rotation speed as the effective temperature decreases; the lower limit rises
to reach critical rotation for the coolest Be stars. The derived lower limits
on equatorial rotation speed represent conservative threshold rotation rates
for the onset of the Be phenomenon. The significantly subcritical speeds found
for early-type Be stars represent strong constraints on physical models of
angular momentum deposition in Be star disks.


title:
The Physical and Photometric Properties of High-Redshift Galaxies in
  Cosmological Hydrodynamic Simulations

abstract:
  We study the physical and photometric properties of galaxies at z=4 in
cosmological hydrodynamic simulations of a lambda-CDM universe. We focus on
galaxies satisfying the GOODS "B-dropout" criteria. Our goals are: (1) to study
the nature of high-redshift galaxies; (2) to test the simulations against
published measurements of high-redshift galaxies; (3) to find relations between
photometric measurements by HST/ACS (0.4 -- 1 micron) and Spitzer/IRAC (3.6 --
8 micron) and the intrinsic physical properties of GOODS "B-dropouts" such as
stellar mass, stellar age, dust reddening, and star-formation rate; and (4) to
assess how representative the GOODS survey is at this epoch. Our simulations
predict that high-redshift galaxies show strong correlations in star formation
rate versus stellar mass, and weaker correlations versus environment and age,
such that GOODS galaxies are predicted to be the most massive, most rapidly
star-forming galaxies at that epoch, living preferentially in dense regions.
The simulated rest-frame UV luminosity function (LF) and integrated luminosity
density are in broad agreement with observations at z~4. The predicted
rest-frame optical (observed 3.6 micron) LF is similar to the rest-frame UV LF,
shifted roughly one magnitude brighter. We predict that GOODS detects less than
50% of the total stellar mass density formed in galaxies more massive than
10^8.7 M_sun by z=4, mainly because of brightness limits in the HST/ACS bands.
The most rapidly star forming galaxies in our simulations have rates exceeding
1000 M_sun yr^-1, similar to observed sub-mm galaxies. The star formation rates
of these galaxies show at most a mild excess (2--3x) over the rates that would
be expected for their stellar mass. Whether these bright galaxies would be
observable as LBGs depends on the uncertain effects of dust reddening.


title: High-Resolution Spectroscopy of Ursa Major Moving Group Stars

abstract:
  We use new and extant literature spectroscopy to address abundances and
membership for UMa moving group stars. We first compare the UMa, Coma, and
Hyades H-R diagrams via a homogeneous set of isochrones, and find that these
three aggregates are essentially coeval. Our spectroscopy of cool UMa dwarfs
reveals striking abundance anomalies--trends with Teff, ionization state, and
excitation potential--like those recently seen in young cool M34, Pleaides, and
Hyades dwarfs. In particular, the trend of rising 7774 Ang-based OI abundance
with declining Teff is markedly subdued in UMa compared to the Pleiades,
suggesting a dependence on age or metallicity. Despite disparate sources of Li
data,our homogeneous analysis indicates that UMa members evince remarkably
small scatter in the Li-Teff plane for Teff>5200 K. Significant star-to-star
scatter suggested by previous studies is seen for cooler stars. Comparison with
the consistently determined Hyades Li-Teff trend reveals differences
qualitatively consistent with this cluster's larger [Fe/H] (and perhaps
slightly larger age). However, quantitative comparison with standard stellar
models indicates the differences are smaller than expected, suggesting the
action of a fourth parameter beyond age, mass, and [Fe/H] controlling Li
depletion.


title:
Globular Clusters in Virgo Ellipticals: Unexpected Results for Giants,
  Dwarfs, and Nuclei from ACS Imaging

abstract:
  We have analyzed archival HST/ACS images in Sloan g and z of the globular
cluster (GC) systems of 53 ellipticals in the Virgo Cluster, spanning massive
galaxies to dEs. Among the new results are: (1) In the gEs M87 and NGC 4649,
there is a correlation between luminosity and color for individual metal-poor
GCs, such that more massive GCs are more metal-rich. A plausible interpretation
of this result is self-enrichment, and may suggest that these GCs once
possessed dark matter halos. (2) Many dEs have metal-rich GC subpopulations. We
also confirm the GC color--galaxy luminosity relations found previously for
both metal-poor and metal-rich GC subpopulations. (3) There are large
differences in GC specific frequency among dEs. Over -15 < M_B < -18, there is
little correlation between specific frequency (S_N)and M_B. But we do find
evidence for two separate S_N classes of dEs: those with B-band S_N ~ 2, and
others with populous GC systems that have S_N ranging from ~ 5-20 with median
S_N ~ 10. Together, these points suggest multiple formation channels for dEs in
Virgo. (4) The peak of the GC luminosity function (GCLF) is the same for both
gEs and dEs. This is contrary to expectations of dynamical friction on massive
GCs, unless the primordial GCLF varies between gEs and dEs. Among gEs the GCLF
turnover varies by a surprising small 0.05 mag, an encouraging result for its
use as an accurate standard candle. (5) dE,Ns appear bimodal in their nuclear
properties: there are small bright red nuclei consistent with formation by
dynamical friction of GCs, and larger faint blue nuclei which appear to have
formed by a dissipative process with little contribution from GCs. The role of
dynamical evolution in shaping the present-day properties of dE GC systems and
their nuclei remains ambiguous. (Abridged)


title: Constraints on supernovae dimming from photon-pseudo scalar coupling

abstract:
  An alternative mechanism that dims high redshift supernovae without cosmic
acceleration utilizes an oscillation of photons into a pseudo-scalar particle
during transit. Since angular diameter distance measures are immune to the loss
of photons, this ambiguity in interpretation can be resolved by combining CMB
acoustic peak measurements with the recent baryon oscillation detection in
galaxy power spectra. This combination excludes a non-accelerating dark energy
species at the 4sigma level regardless of the level of the pseudo-scalar
coupling. While solutions still exist with substantial non-cosmological dimming
of supernovae, they may be tested with future improvement in baryon oscillation
experiments.


title:
The XMM Large-Scale Structure Survey: An initial sample of galaxy groups
  and clusters to a redshift z<0.6

abstract:
  We present X-ray and optical spectroscopic observations of twelve galaxy
groups and clusters identified within the XMM Large-Scale Structure (LSS)
survey. Groups and clusters are selected as extended X-ray sources from a 3.5
deg2 XMM image mosaic above a flux limit 8e-15 ergs/s/cm2 in the [0.5-2] keV
energy band. Deep BVRI images and multi-object spectroscopy confirm each source
as a galaxy concentration located within the redshift interval 0.29<z<0.56. We
combine line-of-sight velocity dispersions with the X-ray properties of each
structure computed from a two-dimensional surface brightness model and a single
temperature fit to the XMM spectral data. The resulting distribution of X-ray
luminosity, temperature and velocity dispersion indicate that the XMM-LSS
survey is detecting low-mass clusters and galaxy groups to redshifts z < 0.6.
Confirmed systems display little or no evidence for X-ray luminosity evolution
at a given X-ray temperature compared to lower redshift X-ray group and cluster
samples. A more complete understanding of these trends will be possible with
the compilation of a statistically complete sample of galaxy groups and
clusters anticipated within the continuing XMM-LSS survey.


title: Keck/HIRES Spectroscopy of Four Candidate Solar Twins

abstract:
  We use high S/N, high-resolution Keck/HIRES spectroscopy of 4 solar twin
candidates (HIP 71813, 76114, 77718, 78399) from our Hipparcos-based CaII H & K
survey to carry out parameter and abundance analyses of these objects. Our
spectroscopic Teff estimates are some 100 K hotter than the photometric scale
of the recent Geneva-Copenhagen survey; several lines of evidence suggest the
photometric temperatures are too cool at solar $T_{\rm eff}$. At the same time,
our abundances for the 3 solar twin candidates included in the
Geneva-Copenhagen survey are in outstanding agreement with the photometric
metallicities; there is no sign of the anomalously low photometric
metallicities derived for some late-G UMa group and Hyades dwarfs. A first
radial velocity determination is made for HIP 78399, and UVW kinematics derived
for all stars. HIP 71813 appears to be a kinematic member of the Wolf 630
moving group (a structure apparently reidentified in a recent analysis of
late-type Hipparcos stars), but its metallicity is 0.1 dex higher than the most
recent estimate of this group's metallicity. While certainly ``solar-type''
stars, HIP 76114 and 77718 are a few percent less massive, significantly older,
and metal-poor compared to the Sun; they are neither good solar twin candidates
nor solar analogs providing a look at the Sun at some other point in its
evolution. HIP 71813 appears to be an excellent solar analog of age 8 Gyr. Our
results for HIP 78399 suggest the promise of this star as a solar twin may be
equivalent to the ``closest ever solar twin'' HR 6060; follow up study of this
star is encouraged.


title: Initial Populations of Black Holes in Star Clusters

abstract:
  Using an updated population synthesis code we study the formation and
evolution of black holes (BHs) in young star clusters following a massive
starburst. This study continues and improves on the initial work described by
Belczynski, Sadowski & Rasio (2004). In our new calculations we account for the
possible ejections of BHs and their progenitors from clusters because of natal
kicks imparted by supernovae and recoil following binary disruptions. The
results indicate that the properties of both retained BHs in clusters and
ejected BHs (forming a field population) depend sensitively on the depth of the
cluster potential. In particular, most BHs ejected from binaries are also
ejected from clusters with central escape speeds Vesc < 100 km/s. Conversely,
most BHs remaining in binaries are retained by clusters with Vesc > 50 km/s.
BHs from single star evolution are also affected significantly: about half of
the BHs originating from primordial single stars are ejected from clusters with
Vesc < 50 km/s. Our results lay a foundation for theoretical studies of the
formation of BH X-ray binaries in and around star clusters, including possible
ultra-luminous sources, as well as merging BH--BH binaries detectable with
future gravitational-wave observatories.


title: How Far Away are Gravitational Lens Caustics? Wrong Question

abstract:
  It has been a persistent question at least for a decade where the
gravitational lens caustics are in the radial direction: whether in front of
the lensing mass, behind the lensing mass, or on the plane normal to the line
of sight that passes through the lensing mass, the radiation source, or the
observer. It is a wrong question. And, the truth angers certain referees who
somehow possess the ability to write lengthy rubbish referee reports and delay
certain papers indefinitely.
  General relativity is a metric theory, particularly of Riemannian geometry,
which is characterized by the existence of an inner product -- or, the
invariance of the proper time. According to Einstein field equations, a compact
mass defines a spherical geometry around it and focuses photons from a distant
source to an observer with the source and observer as the two focal points.
When the mass is spherically symmetric, the two dimensional lens equation that
relates the angular positions of a source and its images defines a point
caustic at the angular position of the lensing mass.
  The third (radial) position of the point caustic is not defined. For an
arbitrary mass, the caustic extends into a web of piecewise smooth curves
punctuated by cusps and again its notion exists only within the context of the
lens equation. We point out a few errors in a couple of papers, published in
the Astrophysical Journal, which may be influential.


title:
The chemistry of planetary nebulae and HII regions in the dwarf galaxies
  Sextans A and B from deep VLT spectra

abstract:
  Spectroscopic observations obtained with the VLT of one planetary nebula (PN)
in Sextans A and of five PNe in Sextans B and of several HII regions (HII) in
these two dwarf irregular galaxies are presented. The extended spectral
coverage, from 320.0 to 1000.0nm, and the large telescope aperture allowed us
to detect a number of emission lines, covering more than one ionization stage
for several elements (He, O, S, Ar). The electron temperature (Te) diagnostic
[OIII] line at 436.3 nm was measured in all six PNe and in several HII allowing
for an accurate determination of the ionic and total chemical abundances by
means of the Ionization Correction Factors method. For the time being, these
PNe are the farthest ones where such a direct measurement of the Te is
obtained. In addition, all PNe and HII were also modelled using the
photoionization code CLOUDY. The physico-chemical properties of PNe and HII are
presented and discussed. A small dispersion in the oxygen abundance of HII was
found in both galaxies: 12 + $\log$(O/H)=7.6$\pm$0.2 in SextansA, and
7.8$\pm$0.2 in SextansB. For the five PNe of SextansA, we find that 12 +
$\log$(O/H)=8.0$\pm$0.3, with a mean abundance consistent with that of HII. The
only PN known in SextansA appears to have been produced by a quite massive
progenitor, and has a significant nitrogen overabundance. In addition, its
oxygen abundance is 0.4 dex larger than the mean abundance of HII, possibly
indicating an efficient third dredge-up for massive, low-metallicity PN
progenitors. The metal enrichment of both galaxies is analyzed using these new
data.


title: The Largest Scale We Can Detect in the Universe and the Inflation

abstract:
  From the damping of the Cosmic Microwave Background Radiation
  (CMB) anisotropy power spectrum at large scale and the recent accelerating
expansion of the Universe, we find that, there may be a largest scale which we
can detect in the Universe. From this, we can get the inflation parameters as
spectrum index $n_s$, e-fold
  $N$, Hubble parameter $H$, the ratio of tensor and scalar $r$, the lasting
time of reheating time $\alpha$ for special inflation models. We do them in
three inflation models, and find that all the results fit very well with the
observations and the inflation theory.


title:
Rotational Evolution of Solar-Like Stars in Clusters from Pre-Main
  Sequence to Main Sequence: Empirical Results

abstract:
  Rotation periods are now available for ~500 pre-main sequence and recently
arrived main sequence stars of solar-like mass (0.4-1.2 M_sun) in five nearby
young clusters: the Orion Nebula Cluster, NGC 2264, alpha Per, IC 2602 and the
Pleiades. In combination with estimates of stellar radii these data allow us to
construct distributions of surface angular momentum per unit mass at three
different epochs: nominally, 1, 2 and 50 My. Our main result is illustrated in
Fig. 18 and may be summarized as follows: (1) 50-60% of the stars on convective
tracks in this mass range are released from any locking mechanism very early on
and are free to conserve angular momentum throughout most of their PMS
evolution, i.e. to spin up and account for the rapidly rotating young main
sequence stars. (2) The other 40-50% lose substantial amounts of angular
momentum during the first few million years, and end up as slowly rotating main
sequence stars. The duration of the rapid angular momentum loss phase is ~5-6
My, which is roughly consistent with the lifetimes of disks estimated from
infrared surveys of young clusters. The rapid rotators of Orion age lose less
than 10% of their (surface) specific angular momentum during the next 50 My
while the slow rotators lose about two-thirds of theirs. A detectable part of
this loss occurs even during the ~1 My interval between the ONC and NGC 2264.
The data support the view that interaction between an accretion disk and star
is the primary mechanism for evolving the broad, bimodal distribution of
rotation rates seen for solar-like stars in the ONC into the even broader
distributions seen in the young MS clusters.


title: Perturbations of the Yang-Mills field in the universe

abstract:
  It has been suggested that the Yang-Mills (YM) field can be a kind of
candidate for the inflationary field at high energy scales or the dark energy
at very low energy scales, which can naturally give the equation of state
$-1<\omega<0$ or $\omega<-1$. We discuss the zero order and first order
Einstein equations and YM field kinetic energy equations of the free YM field
models. From the zero order equations, we find that $\omega+1\propto a^{-2}$,
from which it follows that the equation of state of YM field always goes to -1,
independent of the initial conditions. By solving the first order Einstein
equations and YM field equations, we find that in the YM field inflationary
models, the scale-invariant primordial perturbation power spectrum cannot be
generated. Therefore, only this kind of YM field is not enough to account for
inflationary sources. However, as a kind of candidate of dark energy, the YM
field has the `sound speed' $c_s^2=-1/3<0$, which makes the perturbation $\phi$
have a damping behavior at the large scale. This provides a way to distinguish
the YM field dark energy models from other kinds of models.


title: GRB050223: A faint Gamma-Ray Burst discovered by Swift

abstract:
  GRB050223 was discovered by the Swift Gamma-Ray Burst Explorer on 23 February
2005 and was the first Gamma-Ray Burst to be observed by both Swift and
XMM-Newton. At the time of writing (May 2005), it has one of the faintest GRB
afterglows ever observed. The spacecraft could not slew immediately to the
burst, so the first X-ray and optical observations occurred approximately 45
minutes after the trigger. Although no optical emission was found by any
instrument, both Swift and XMM-Newton detected the fading X-ray afterglow.
Combined data from both of these observatories show the afterglow to be fading
monotonically as 0.99 +0.15/-0.12 over a time frame between 45 minutes to 27
hours post-burst. Spectral analysis, allowed largely by the higher through-put
of XMM-Newton, implies a power-law with a slope of Gamma=1.75 +0.19/-0.18 and
shows no evidence for absorption above the Galactic column of 7 x 10^20 cm^-2.
  From the X-ray decay and spectral slopes, a low electron power-law index of p
= 1.3-1.9 is derived; the slopes also imply that a jet-break has not occured up
to 27 hours after the burst. The faintness of GRB050223 may be due to a large
jet opening or viewing angle or a high redshift.


title:
Measuring Fundamental Galactic Parameters with Stellar Tidal Streams and
  SIM PlanetQuest

abstract:
  Extended halo tidal streams from disrupting Milky Way satellites offer new
opportunities for gauging fundamental Galactic parameters without challenging
observations of the Galactic center. In the roughly spherical Galactic
potential tidal debris from a satellite system is largely confined to a single
plane containing the Galactic center, so accurate distances to stars in the
tidal stream can be used to gauge the Galactic center distance, R_0, given
reasonable projection of the stream orbital pole on the X_GC axis.
Alternatively, a tidal stream with orbital pole near the Y_GC axis, like the
Sagittarius stream, can be used to derive the speed of the Local Standard of
Rest (\Theta_LSR). Modest improvements in current astrometric catalogues might
allow this measurement to be made, but NASA's Space Interferometry Mission (SIM
PlanetQuest) can definitively obtain both R_0 and \Theta_LSR using tidal
streams.


title:
High and ultra-high energy cosmic ray acceleration in
  structure-formation shocks in Abell 3376 galaxy cluster

abstract:
  We describe multiwavelength optical, X-ray and radio evidences of energetic
mergers in southern galaxy cluster Abell 3376 (A3376, redshift z=0.046, X-ray
luminosity $ \rm L_{X}(0.1-2.4 keV)= 2.48 \times 10^{44} erg s^{-1}$). Here we
report the rare discovery of gigantic, Mpc-scale non-thermal radio structures
(`radio-arcs'), shaped like a pair of bow-shock fronts on the merger axis. We
argue for the shock acceleration origin of the radio emission and discuss the
possibilty of acceleration of very high energy cosmic ray particles in this and
similar clusters. At redshift z=0.04, cluster A3376 is near enough that some of
these primary or secondary cosmic ray components could actually be detected by
new cosmic ray telescopes, particularly the energetic inverse Compton hard
X-ray/gamma-ray photons upto extreme energies $E_{\gamma} \sim 100
{\gamma^{e}_{7}}^{2}$ GeV (where ${\gamma^{e}_{7}}$ is the electron Lorentz
factor in units of $10^7$). Identification of radio or hard X-ray/gamma-ray
emission from structure formation shocks holds a great promise for advancing
current knowledge on shock formation in the IGM. It should provide the first
direct evidence for such shocks, revealing the underlying large-scale
cosmological flows. When combined with hard X-ray or gamma-ray detection, the
radio signal will provide a direct measure of the unknown magnetic fields in
the IGM, thus providing a better understanding of processes leading to IGM
magnetization and also acceleration and propagation of ultra-high energy cosmic
rays.


title: A review of experimental results at the knee

abstract:
  Results of experiments investigating air showers in the energy region of the
knee are summarized. The all-particle energy spectrum, the mean logarithmic
mass, and the average depth of the shower maximum will be discussed.
  Spectra for groups of elements from air shower data are compared to results
from direct measurements.


title:
The end of the galactic cosmic-ray energy spectrum - a phenomenological
  view

abstract:
  Two structures in the all-particle energy spectrum of cosmic rays, the knee
at
  4 PeV and the second knee around 400 PeV are proposed to be explained by a
phenomenological model, the poly gonato model, connecting direct and indirect
measurements. Within this approach the knee is caused by a successive cut-off
of the flux for individual elements starting with protons at 4.5 PeV. The
second knee is interpreted as the end of the stable nuclei of the periodic
table. To check some key features of this model calculations of the cosmic ray
energy spectrum and the propagation path length at energies from 10^14 to 10^19
eV have been performed within the framework of a combined approach based on the
diffusion model of cosmic rays and a direct simulation of charged-particle
trajectories in the Galaxy.


title: The Dependence of Galaxy Colors on Luminosity and Environment at z~0.4

abstract:
  We analyse the B-R_c colors of galaxies as functions of luminosity and local
galaxy density using a large photometric redshift catalog based on the
Red-Sequence Cluster Survey. We select two samples of galaxies with a magnitude
limit of M_Rc<-18.5 and redshift ranges of 0.2<z< 0.4 and 0.4<z<0.6 containing
\~10^5 galaxies each. We model the color distributions of subsamples of
galaxies and derive the red galaxy fraction and peak colors of red and blue
galaxies as functions of galaxy luminosity and environment. The evolution of
these relationships over the redshift range of z~0.5 to z~0.05 is analysed in
combination with published results from the Sloan Digital Sky Survey. We find
that there is a strong evolution in the restframe peak color of bright blue
galaxies in that they become redder with decreasing redshift, while the colors
of faint blue galaxies remain approximately constant. This effect supports the
``downsizing'' scenario of star formation in galaxies. While the general
dependence of the galaxy color distributions on the environment is small, we
find that the change of red galaxy fraction with epoch is a function of the
local galaxy density, suggesting that the downsizing effect may operate with
different timescales in regions of different galaxy densities.


title:
The All Sky Automated Survey. The Catalog of Variable Stars. V.
  Declinations 0 deg - 28 deg of the Northern Hemisphere

abstract:
  This paper contains the fifth part of the Catalog of Variable Stars created
from the V-band photometric data collected by 9x9 deg camera of the All Sky
Automated Survey. Preliminary list of variable stars found in the fields
located between declination 0 and +28 deg of the northern hemisphere is
presented. 11,509 stars brighter than V=15 were found to be variable (2,482
eclipsing, 1,397 regularly pulsating, 318 Mira and 7,310 other stars).
Automated algorithm taking into account light curve properties (period, fourier
coefficients) and other available data (2MASS colors, IRAS fluxes) was applied
to roughly classify objects. Basic photometric properties are presented in the
tables and thumbnail light curves are made available for reference. All the
photometric data are available over the INTERNET at
http://www.astrouw.edu.pl/~gp/asas/asas.html or
http://archive.princeton.edu/~asas


title: The stellar population and interstellar medium in NGC 6822

abstract:
  We present a comprehensive study of the stellar population and the
interstellar medium in NGC 6822 using high-quality \HI data (obtained with the
Australia Telescope Compact Array) and optical broad/narrow-band data (obtained
with Subaru and the INT). Our H$\alpha$ observations are an order of magnitude
deeper than previous studies and reveal a complex filamentary network covering
almost the entire central disk of NGC 6822. We find hitherto unknown HII
regions in the outskirts of NGC 6822 and the companion galaxy. The old and
intermediate age stellar population can be traced out to radii of over 0.6 deg
(> 5 kpc), significantly more extended than the HI disk. In sharp contrast, the
distribution of the young, blue stars, closely follows the distribution of the
HI disk and displays a highly structured morphology. We find evidence for an
older stellar population in the companion galaxy -- the current star formation
activity, although likely to have been triggered by the interaction with NGC
6822, is not the first star formation episode in this object. We show that the
properties of the giant kpc-sized hole in the outer HI disk of NGC 6822 are
consistent with it being formed by the effects of stellar evolution.


title:
Heteroclinic orbit and tracking attractor in cosmological model with a
  double exponential potential

abstract:
  In this paper, the dynamical heteroclinic orbit and attractor have been
employed to make the late-time behaviors of the model insensitive to the
initial condition and thus alleviates the fine tuning problem in cosmological
dynamical system of barotropic fluid and quintessence with a double exponential
potential. The late-time asymptotic behavior of the double exponential model
does not always correspond to the single case. The heteroclinic orbits are the
non-stationary solutions and in general they will interpolate between the
critical points. Although they can not be shown analytically, yet a numerical
calculation can reveal most of their properties. Varied heteroclinic orbits and
attractors including tracking attractor and de Sitter attractor have been
found.


title: SAPAC: a SBF analysis pipeline for the astronomical community

abstract:
  Large volumes of CCD imaging data that will become available from wide-field
cameras at telescopes such as the CFHT, SUBARU, VST, or VISTA in the near
future are highly suitable for systematic distance surveys of early-type
galaxies using the Surface Brightness Fluctuation (SBF) method. For the
efficient processing of such large data sets, we are developing the first
semi-automatic SBF analysis pipeline named SAPAC. After a brief description of
the SBF method we discuss the image quality needed for a successful distance
measurement and give some background information on SAPAC


title:
Captures of Red Giant Stars by Black Holes in Elliptical Galaxies:
  Feedback to the Hot Gas

abstract:
  The highly disturbed hot gas in elliptical galaxies, as revealed in many {\em
Chandra} X-ray images, implies a source of energy in the galactic nucleus. In
some elliptical galaxies faint X-ray ``ghost'' cavities appear without
corresponding radio lobes. It has been suggested that ghost cavities are caused
by short-lived activity with a timescale of $\sim 10^3-10^4$ years, but this is
difficult to understand within the popular paradigm of active galactic nuclei.
We suggest an episode model for ghost cavities, invoking captures of red giant
stars by the black hole located at the center of the elliptical galaxies at a
typical rate of $10^{-5}$yr$^{-1}$ per galaxy. The accretion of tidally
disrupted red giant stars onto the black hole powers activity in a timescale of
a few years. The total energy channeled into the jet/outflow during the cooling
time of the hot gas is $\sim 10^{56}$ erg, which is the typical work required
to form the observed cavities. In this scenario, the faint cavities are
produced by the feedback following accretion of the debris of the captured red
giant stars onto the black holes. We apply the present model to several
elliptical galaxies and find that it can explain the formation of the ghost
cavities. This model can be tested in the future by comparisons between radio
and X-ray observations.


title:
Observational Constraints on the Role of the Crust in the Post-glitch
  Relaxation

abstract:
  The observed large rates of spinning down after glitches in some radio
pulsars have been previously explained in terms of a long-term spin-up behavior
of a superfluid part of the crust of neutron stars. We argue that the suggested
mechanism is not viable; being inconsistent with the basic requirements for a
superfluid spin-up, in addition to its quantitative disagreement with the data.
Hence, the observed post-glitch relaxations may not be interpreted due only to
the effects of the stellar crust.


title: A Gamma-Ray Bursts' Fluence-Duration Correlation

abstract:
  We present an analysis indicating that there is a correlation between the
fluences and the durations of gamma-ray bursts, and provide arguments that this
reflects a correlation between the total emitted energies and the intrinsic
durations. For the short (long) bursts the total emitted energies are roughly
proportional to the first (second) power of the intrinsic duration. This
difference in the energy-duration relationship is statistically significant,
and may provide an interesting constraint on models aiming to explain the short
and long gamma-ray bursts.


title:
Propagating Oscillatory Shock Model for QPOS in GRO J1655-40 During the
  March 2005 Outburst

abstract:
  GRO 1655-40, a well known black hole candidate, showed renewed X-ray activity
in March 2005 after being dormant for almost eight years. It showed very
prominent quasi-periodic oscillations. We analysed the data of two observations
in this {\it Rapid Communication}, one taken on March 2nd, 2005 and the other
taken on the March 11th, 2005. On March 2nd, 2005 the shock was weak and the
QPO was seen in roughly all energies. On March 11th, 2005 the power density
spectra showed that quasi-periodic oscillations (QPOs) were exhibited in harder
X-rays. On the first day, the QPO was seen at 0.13Hz and on the second day, the
QPO was seen at $\sim 6.5$Hz with a spectral break at $\sim 0.1$Hz. We analysed
the QPOs for the period 25th Feb. 2005 to 12th of March, 2005 and showed that
the frequency of QPO increased monotonically from 0.088Hz to 15.01Hz. This
agrees well if the oscillating shock is assumed to propagate with a constant
velocity. On several days we also noticed the presence of very high frequency
QPOs and for the first time we detected QPOs in the 600-700Hz range, the
highest frequency range so far reported for any black hole candidate.


title: Spitzer Observations Of The Supergiant Shell Region In IC 2574

abstract:
  We present spatially resolved Spitzer imaging of the supergiant shell region
of the M81 group dwarf galaxy IC 2574 obtained as part of the Spitzer Infrared
Nearby Galaxies Survey. This region harbors one of the best nearby examples of
a kinematically distinct HI shell, with an associated remnant stellar cluster;
the shell is initiating sequential star formation as it interacts with the
surrounding interstellar medium. This region dominates the infrared luminosity
of IC 2574 and is spatially resolved in all Spitzer imaging bands. We study the
differences in dust temperature as a function of local environment and compare
local star formation rates as inferred from H Alpha and total infrared
luminosities. We find that the strong H Alpha sources are associated with
regions of warm dust; however, the most luminous infrared and H Alpha sources
are not necessarilyco-spatial. The coolest dust is found in the regions
farthest from the rim of the shell; these regions show the best agreement
between star formation rates derived from H Alpha and from total infrared
luminosities (although discrepancies at the factor of 3-4 level still exist).
There is considerable variation in the radio-far infrared correlation in
different regions surrounding the shell. The low dust content of the region may
influence the scatter seen in these relations; these data demonstrate that the
expanding shell is dramatically affecting its surroundings by triggering star
formation and altering the dust temperature.


title:
The effect of grain size distribution on H$_2$ formation rate in the
  interstellar medium

abstract:
  The formation of molecular hydrogen in the interstellar medium takes place on
the surfaces of dust grains. Hydrogen molecules play a role in gas-phase
reactions that produce other molecules, some of which serve as coolants during
gravitational collapse and star formation. Thus, the evaluation of the
roduction rate of hydrogen molecules and its dependence on the physical
conditions in the cloud are of great importance. Interstellar dust grains
exhibit a broad size distribution in which the small grains capture most of the
surface area. Recent studies have shown that the production efficiency strongly
depends on the grain composition and temperature as well as on its size. In
this paper we present a formula which provides the total production rate of
H$_2$ per unit volume in the cloud, taking into account the grain composition
and temperature as well as the grain size distribution. The formula agrees very
well with the master equation results. It shows that for a physically relevant
range of grain temperatures, the production rate of H$_2$ is significantly
enhanced due to their broad size distribution.


title:
Dissecting the spiral galaxy M83: mid-infrared emission and comparison
  with other tracers of star formation

abstract:
  We present a detailed mid-infrared study of the nearby, face-on spiral galaxy
M83 based on ISOCAM data. M83 is a unique case study, since a wide variety of
MIR broad-band filters as well as spectra, covering the wavelength range of 4
to 18\mu m, were observed and are presented here. Emission maxima trace the
nuclear and bulge area, star-formation regions at the end of the bar, as well
as the inner spiral arms. The fainter outer spiral arms and interarm regions
are also evident in the MIR map. Spectral imaging of the central 3'x3' (4 kpc x
4 kpc) field allows us to investigate five regions of different environments.
The various MIR components (very small grains, polycyclic aromatic hydrocarbon
(PAH) molecules, ionic lines) are analyzed for different regions throughout the
galaxy. In the total 4\mu m to 18\mu m wavelength range, the PAHs dominate the
luminosity, contributing between 60% in the nuclear and bulge regions and 90%
in the less active, interarm regions. Throughout the galaxy, the underlying
continuum emission from the small grains is always a smaller contribution in
the total MIR wavelength regime, peaking in the nuclear and bulge components.
The implications of using broad-band filters only to characterize the
mid-infrared emission of galaxies, a commonly used ISOCAM observation mode, are
discussed. We present the first quantitative analysis of new H-alpha and 6cm
VLA+Effelsberg radio continuum maps of M83. The distribution of the MIR
emission is compared with that of the CO, HI, R band, H-alpha and 6cm radio. A
striking correlation is found between the intensities in the two mid-infrared
filter bands and the 6cm radio continuum. To explain the tight
mid-infrared-radio correlation we propose the anchoring of magnetic field lines
in the photoionized shells of gas clouds.


title: HD 12098 and other results from NainiTal-Cape survey

abstract:
  NainiTal-Cape Survey is a survey started with the aim of searching for new
rapidly oscillating Ap stars in the northern hemisphere and has discovered one
mono-periodic roAp star HD 12098. The frequency separation of HD 12098 suggests
a rotation period of 5.5 day for the star. The discovery of roAp oscillations
in HD 12098 and the results of the multi-site observation campaign organized to
resolve the ambiguity in the determination of the rotation period of HD 12098
is presented. The results of non oscillating Ap stars discovered in the survey
and two promising roAp candidates HD 17431 and HD 207561 are also presented. If
confirmed, the variability in HD 207561 will make it the first Am star showing
roAp type rapid variability.


title: On the distribution of the modulation frequencies of RR Lyrae stars

abstract:
  For the first time connection between the pulsation and modulation properties
of RR Lyrae stars has been detected. Based on the available data it is found
that the possible range of the modulation frequencies, i.e, the possible
maximum value of the modulation frequency depends on the pulsation frequency.
Short period variables (P < 0.4 d) can have modulation period as short as some
days, while longer period variables (P > 0.6 d) always exhibit modulation with
P_mod > 20 d. We interpret this tendency with the equality of the modulation
period with the surface rotation period, because similar distribution of the
rotational periods is expected if an upper limit of the total angular momentum
of stars leaving the RGB exists. The distribution of the projected rotational
velocities of red and blue horizontal branch stars at different temperatures
shows a similar behaviour as v_rot derived for RR Lyrae stars from their
modulation periods. This common behaviour gives reason to identify the
modulation period with the rotational period of the modulated RR Lyrae stars.


title: Initial Conditions for Massive Star Birth -- Infrared Dark Clouds

abstract:
  We summarize the properties of Infrared Dark Clouds, massive, dense, and cool
aggregations of interstellar gas and dust that are found througout the Galaxy
in projection against the strong mid-infrared background. We describe their
distribution and give an overview of their physical properties and chemistry.
These objects appear to be the progenitors of high-mass stars and star
clusters, but seem to be largely devoid of star formation, which however is
taking place in localized spots.


title: The thermonuclear production of F19 by Wolf-Rayet stars revisited

abstract:
  New models of rotating and non-rotating stars are computed for initial masses
between 25 and 120 Msun and for metallicities Z = 0.004, 0.008, 0.020 and 0.040
with the aim of reexamining the wind contribution of Wolf-Rayet (WR) stars to
the F19 enrichment of the interstellar medium. Models with an initial rotation
velocity vini = 300 km/s are found to globally eject less F19 than the
non-rotating models. We compare our new predictions with those of Meynet &
Arnould (2000), and demonstrate that the F19 yields are very sensitive to the
still uncertain F19(alpha,p)Ne22 rate and to the adopted mass loss rates. Using
the recommended mass loss rate values that take into account the clumping of
the WR wind and the NACRE reaction rates when available, we obtain WR F19
yields that are significantly lower than predicted by Meynet & Arnould (2000),
and that would make WR stars non-important contributors to the galactic F19
budget. In view, however, of the large nuclear and mass loss rate
uncertainties, we consider that the question of the WR contribution to the
galactic F19 remains quite largely open.


title: Planar Integrated Optics and astronomical interferometry

abstract:
  Integrated optics (IO) is an optical technology that allows to reproduce
optical circuits on a planar substrate. Since 1996, we have investigated the
potentiality of IO in the framework of astronomical single mode interferometry.
We review in this paper the principles of IO, the requirements for
interferometry and the corresponding solutions offered by IO, the results of
component characterization and the possible fields of application.


title:
Isotopic abundances of carbon and nitrogen in Jupiter-family and Oort
  Cloud comets

abstract:
  The 12C14N/12C15N and 12C14N/13C14N isotopic ratios are determined for the
first time in a Jupiter-family comet, 88P/1981 Q1 Howell, and in the chemically
peculiar Oort Cloud comet C/1999 S4 (LINEAR). By comparing these measurements
to previous ones derived for six other Oort Cloud comets (including one of
Halley-type), we find that both the carbon and nitrogen isotopic ratios are
constant within the uncertainties. The mean values are 12C/13C ~ 90 and 14N/15N
\~ 145 for the eight comets. These results strengthen the view that CN radicals
originate from refractory organics formed in the protosolar molecular cloud and
subsequently incorporated in comets.


title:
Non-thermal Cosmic Backgrounds from Blazars: the contribution to the
  CMB, X-ray and gamma-ray Backgrounds

abstract:
  We present a new assessment of the contribution of Blazars to the
extragalactic background radiation across the e.m. spectrum. Our calculations
rely on deep Blazar radio counts that we derived combining several
multifrequency surveys. The integrated Blazar emission yields a broad-band
non-thermal background that in some parts of the e.m. spectrum dominates the
extragalactic brightness. Blazars are the main point-like contributors to the
CMB. Their integrated emission causes an apparent T increase of 5-50 muK in the
50-250 GHz range. The CMB fluctuation spectrum is sensibly contaminated at
l>300, for a Poissonian source distribution, or at lower l values if spatial
clustering is present. We estimate that well over 100,000 Blazars will produce
a significant signal in the PLANCK CMB anisotropy maps. Because of the
microwave-Xray flux correlation, these sources are expected to have flux > a
few 10^{-15} erg/s in the soft X-ray band. Thus, a large fraction of the
foreground sources in CMB anisotropy maps could be identified and removed using
a multi frequency approach, provided that a sufficiently deep all sky X-ray
survey will be available. We further show that Blazars are a major constituent
of all high-E extragalactic backgrounds. Their contribution is 11-12% at X-ray
frequencies and possibly 100% in the 0.5-50 MeV band. At E>100 MeV, the Blazar
collective emission, obtained extrapolating their integrated micro-wave flux to
the gamma-ray band using the SED of EGRET detected sources, over-predicts the
extragalactic background by a large factor, implying that Blazars not only
dominate the gamma-ray sky but also that their average duty cycle at these
frequencies must be rather low. We also find that Blazars of the HBL type may
produce a significant amount of flux at TeV energies.


title:
Probing the birth of the first quasars with the future far infrared
  mission

abstract:
  It is now widely recognised that massive black holes must have had a
fundamental influence on the formation of galaxies and vice versa. With current
and imminent missions we aim to unravel much of this relationship for the last
10 Gyr of cosmic history, while the quasar population waned and star formation
died down. The picture at earlier times will be more difficult to reconstruct,
but will likely be even more exciting: when the first stars shone, the first
dust was formed, and quasars were a vigorously rising population. One of the
primary goals of XEUS is to allow us to find and study the earliest quasars,
however deeply buried in gas and dust they may be. But to understand fully the
astrophysical context of these objects, their significance in the grand
picture, we must learn how they relate to their environments and their host
galaxies. The ESA future Far-InfraRed Mission (FIRM) will provide much of the
data we require, revealing the dust heated by star formation in the host
galaxy, the relative evolutionary stages of spheroid and black hole, and the
total energy budgets posessed by these first quasars. FIRM will reveal star
formation in the immediate proto-cluster environment of the quasar and so tell
us how the formation of the first galaxies and quasars coupled to the earliest
large scale structures.


title: Anomalously Weak Dynamical Friction in Halos

abstract:
  A bar rotating in a pressure-supported halo generally loses angular momentum
and slows down due to dynamical friction. Valenzuela & Klypin report a
counter-example of a bar that rotates in a dense halo with little friction for
several Gyr, and argue that their result invalidates the claim by Debattista &
Sellwood that fast bars in real galaxies require a low halo density. We show
that it is possible for friction to cease for a while should the pattern speed
of the bar fluctuate upward. The reduced friction is due to an anomalous
gradient in the phase-space density of particles at the principal resonance
created by the earlier evolution. The result obtained by Valenzuela & Klypin is
probably an artifact of their adaptive mesh refinement method, but anyway could
not persist in a real galaxy. The conclusion by Debattista & Sellwood still
stands.


title: Multiple CO lines in SMM J16359+6612 -- Further evidence for a merger

abstract:
  Using the IRAM 30m telescope, we report the detection of the CO(3--2),
CO(4--3), CO(5--4) and CO(6--5) lines in the gravitational lensed submm galaxy
SMM J16359+6612 at z=2.5. The CO lines have a double peak profile in all
transitions. From a Gaussian decomposition of the spectra we show that the CO
line ratios, and therefore the underlying physical conditions of the gas, are
similar for the blue and the redshifted component. The CO line Spectral Energy
Distribution (SED; i.e. flux density vs. rotational quantum number) turns over
already at the CO(5--4) transition which shows that the molecular gas is less
excited than in nearby starburst galaxies and high--z QSOs. This difference
mainly arises from a lower average H2 density, which indicates that the gas is
less centrally concentrated than in nuclear starburst regions in local
galaxies. We suggest that the bulk of the molecular gas in SMM J16359+6612 may
arise from an overlap region of two merging galaxies. The low gas density and
clear velocity separation may reflect an evolutionary stage of the merger event
that is in between those seen in the Antennae and in the more evolved
ultraluminous infrared galaxies (ULIRGs) like e.g. Mrk231.


title:
The aperture for UHE tau neutrinos of the Auger fluorescence detector
  using a Digital Elevation Map

abstract:
  We perform a new study of the chances of the fluorescence detector (FD) at
the Pierre Auger Observatory to detect the tau leptons produced by
Earth-skimming ultra high energy tau neutrinos. We present a new and more
detailed evaluation of the effective aperture of the FD that considers a
reliable fiducial volume for the experimental set up. In addition, we take into
account the real elevation profile of the area near Auger. We find a
significant increase in the number of expected events with respect to the
predictions of a previous semi-analytical determination, and our results show
the enhancement effect for neutrino detection from the presence of the near
mountains.


title:
High-speed, multi-colour optical photometry of the anomalous X-ray
  pulsar 4U 0142+61 with ULTRACAM

abstract:
  We present high-speed, multi-colour optical photometry of the anomalous X-ray
pulsar 4U 0142+61, obtained with ULTRACAM on the 4.2-m William Herschel
Telescope. We detect 4U 0142+61 at magnitudes of i'=23.7+-0.1, g'=27.2+-0.2 and
u'>25.8, consistent with the magnitudes found by Hulleman et al.(2004) and
hence confirming their discovery of both a spectral break in the optical and a
lack of long-term optical variability. We also confirm the discovery of Kern &
Martin (2002) that 4U 0142+61 shows optical pulsations with an identical period
(~8.7 s) to the X-ray pulsations. The rms pulsed fraction in our data is
29+-8%, 5-7 times greater than the 0.2-8 keV X-ray rms pulsed fraction. The
optical and X-ray pulse profiles show similar morphologies and appear to be
approximately in phase with each other, the former lagging the latter by only
0.04+-0.02 cycles. In conjunction with the constraints imposed by X-ray
observations, the results presented here favour a magnetar interpretation for
the anomalous X-ray pulsars.


title: Massive Coronae of Galaxies

abstract:
  There is reason to suspect that about half of the baryons are in
pressure-supported plasma in the halos of normal galaxies, drawn in by gravity
along with about half of the dark matter. To be consistent with the
observations this baryonic component, the corona, would have to be hotter than
the kinetic temperature of the dark matter in the halo so as to produce
acceptable central electron densities. We ascribe this hotter plasma
temperature to the addition of entropy prior to and during assembly of the
system, in an analogy to cluster formation. The plasma cooling time would be
longer than the gravitational collapse time but, in the inner parts, shorter
than the Hubble time, making the corona thermally unstable to the formation of
a cloudy structure that may be in line with what is indicated by quasar
absorption line systems. The corona of an isolated spiral galaxy would be a
source of soft X-ray and recombination radiation, adding to the more commonly
discussed effects of stars and supernovae. In this picture the mass in the
corona is much larger than the mass in condensed baryons in a spiral galaxy.
The corona thus would be a substantial reservoir of diffuse baryons that are
settling and adding to the mass in interstellar matter and stars, so that star
formation in isolated spirals will continue well beyond the present epoch.


title:
New type of magneto-rotational instability in cylindrical Taylor-Couette
  flow

abstract:
  We study the stability of cylindrical Taylor-Couette flow in the presence of
combined axial and azimuthal magnetic fields, and show that adding an azimuthal
field profoundly alters the previous results for purely axial fields. For small
magnetic Prandtl numbers Pm, the critical Reynolds number Re_c for the onset of
the magneto-rotational instability becomes independent of Pm, whereas for
purely axial fields it scales as Pm^{-1}. For typical liquid metals, Re_c is
then reduced by several orders of magnitude, enough that this new design should
succeed in realizing this instability in the laboratory.


title:
A COMPLETE Look at The Use of IRAS Emission Maps to Estimate Extinction
  and Dust Temperature

abstract:
  We have created new dust temperature and column density maps of Perseus,
Ophiuchus and Serpens using 60 and 100 micron data from the IRIS recalibration
of IRAS data. We describe an optimized method for finding the dust temperature,
emissivity spectral index, and optical depth using optical and NIR extinction
maps. The creation of these temperature and extinction maps (covering tens of
square degrees of molecular clouds) is one of the first results from the
ongoing COordinated Molecular Probe Line Extinction Thermal Emission (COMPLETE)
Survey of Star Forming regions. However, while the extinctions derived from the
IRIS emission maps are globally accurate, we warn that FIR emission is not a
good proxy for extinction on the scale of one pixel (5').


title:
Discovery of a Magnetic White Dwarf/Probable Brown Dwarf Short-Period
  Binary

abstract:
  The magnetic white dwarf SDSS J121209.31+013627.7 exhibits a weak, narrow
Halpha emission line whose radial velocity and strength are modulated on a
period of ~90 minutes. Though indicative of irradiation on a nearby companion,
no cool continuum component is evident in the optical spectrum, and IR
photometry limits the absolute magnitude of the companion to M_J > 13.37. This
is equivalent to an isolated L5 dwarf, with T_eff < 1700 K. Consideration of
possible evolutionary histories suggests that, until ~0.6 Gyr ago, the brown
dwarf orbited a ~1.5 M_sun main seqeunce star with P ~ 1 yr, a ~ 1 AU, thus
resembling many of the gaseous superplanets being found in extrasolar planet
searches. Common envelope evolution when the massive star left the main
sequence reduced the period to only a few hours, and ensuing angular momentum
loss has further degraded the orbit. The binary is ripe for additional
observations aimed at better studying brown dwarfs and the effects of
irradiation on their structure.


title:
HST/Acs Weak-Lensing and Chandra X-Ray Studies of the High-Redshift
  Cluster MS 1054-0321

abstract:
  We present Hubble Space Telescope/Advanced Camera for Surveys (ACS)
weak-lensing and Chandra X-ray analyses of MS 1054-0321 at z=0.83, the most
distant and X-ray luminous cluster in the Einstein Extended Medium-Sensitivity
Survey (EMSS). The high-resolution mass reconstruction through ACS weak-lensing
reveals the complicated dark matter substructure in unprecedented detail,
characterized by the three dominant mass clumps with the four or more minor
satellite groups within the current ACS field. The direct comparison of the
mass map with the Chandra X-ray image shows that the eastern weak-lensing
substructure is not present in the X-ray image and, more interestingly, the two
X-ray peaks are displaced away from the hypothesized merging direction with
respect to the corresponding central and western mass clumps, possibly because
of ram pressure. In addition, as observed in our previous weak-lensing study of
another high-redshift cluster CL 0152-1357 at z=0.84, the two dark matter
clumps of MS 1054-0321 seem to be offset from the galaxy counterparts. We
examine the significance of these offsets and discuss a possible scenario,
wherein the dark matter clumps might be moving ahead of the cluster galaxies.
The non-parametric weak-lensing mass modeling gives a projected mass of M(r<1
Mpc)=(1.02+-0.15)x 10^{15} solar mass, where the uncertainty reflects both the
statistical error and the cosmic shear effects. Our temperature measurement of
T=8.9_{-0.8}^{+1.0} keV utilizing the newest available low-energy quantum
efficiency degradation prescription for the Chandra instrument, together with
the isothermal beta description of the cluster (r_c=16"+-15" and
beta=0.78+-0.08), yields a projected mass of M(r<1 Mpc)=(1.2+-0.2) x 10^{15}
solar mass, consistent with the weak-lensing result.


title:
Measurement of Noisy Absorption Lines using the Apparent Optical Depth
  Technique

abstract:
  To measure the column densities of interstellar and intergalactic gas clouds
using absorption line spectroscopy, the apparent optical depth technique (AOD)
of Savage & Sembach (1991) can be used instead of a curve-of-growth analysis or
profile fit. We show that the AOD technique, whilst an excellent tool when
applied to data with good S/N, will likely overestimate the true column
densities when applied to data with low S/N. This overestimation results from
the non-linear relationship between the flux falling on a given detector pixel
and the apparent optical depth in that pixel. We use Monte Carlo techniques to
investigate the amplitude of this overestimation when working with data from
the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Space Telescope
Imaging Spectrograph (STIS), for a range of values of S/N, line depth, line
width, and rebinning. AOD measurements of optimally sampled, resolved lines are
accurate to within 10% for FUSE/LiF and STIS/E140M data with S/N>7 per
resolution element.


title:
The many lives of active galactic nuclei: cooling flows, black holes and
  the luminosities and colours of galaxies

abstract:
  We simulate the growth of galaxies and their central supermassive black holes
by implementing a suite of semi-analytic models on the output of the Millennium
Run, a very large simulation of the concordance LCDM cosmogony. Our procedures
follow the detailed assembly history of each object and are able to track the
evolution of all galaxies more massive than the Small Magellanic Cloud
throughout a volume comparable to that of large modern redshift surveys. In
this first paper we supplement previous treatments of the growth and activity
of central black holes with a new model for `radio' feedback from those AGN
that lie at the centre of a quasistatic X-ray emitting atmosphere in a galaxy
group or cluster. We show that for energetically and observationally plausible
parameters such a model can simultaneously explain: (i) the low observed mass
drop-out rate in cooling flows; (ii) the exponential cut-off at the bright end
of the galaxy luminosity function; and (iii) the fact that the most massive
galaxies tend to be bulge-dominated systems in clusters and to contain
systematically older stars than lower mass galaxies. This success occurs
because static hot atmospheres form only in the most massive structures, and
radio feedback (in contrast, for example, to supernova or starburst feedback)
can suppress further cooling and star formation without itself requiring star
formation. We discuss possible physical models which might explain the
accretion rate scalings required for our phenomenological `radio mode' model to
be successful.


title: On the large-angle anomalies of the microwave sky

abstract:
  [Abridged] We apply the multipole vector framework to full-sky maps derived
from the first year WMAP data. We significantly extend our earlier work showing
that the two lowest cosmologically interesting multipoles, l=2 and 3, are not
statistically isotropic. These results are compared to the findings obtained
using related methods. In particular, the planes of the quadrupole and the
octopole are unexpectedly aligned. Moreover, the combined quadrupole plus
octopole is surprisingly aligned with the geometry and direction of motion of
the solar system: the plane they define is perpendicular to the ecliptic plane
and to the plane defined by the dipole direction, and the ecliptic plane
carefully separates stronger from weaker extrema, running within a couple of
degrees of the null-contour between a maximum and a minimum over more than
120deg of the sky. Even given the alignment of the quadrupole and octopole with
each other, we find that their alignment with the ecliptic is unlikely at >98%
C.L., and argue that it is in fact unlikely at >99.9% C.L. We explore the role
of foregrounds showing that the known Galactic foregrounds are unlikely to lead
to these correlations. Multipole vectors, like individual a_lm, are very
sensitive to sky cuts, and we demonstrate that analyses using cut skies induce
relatively large errors, thus weakening the observed correlations but
preserving their consistency with the full-sky results. Finally we apply our
tests to COBE cut-sky maps and briefly extend the analysis to higher
multipoles. If the correlations we observe are indeed a signal of non-cosmic
origin, then the lack of low-l power will very likely be exacerbated, with
important consequences for our understanding of cosmology on large scales.


title: Did Boomerang hit MOND?

abstract:
  Purely baryonic dark matter dominated models like MOND based on modification
of Newtonian gravity have been successfully in reproducing some dynamical
properties of galaxies. More recently, a relativistic formulation of MOND
proposed by Bekenstein seems to agree with cosmological large scale structure
formation. In this work, we revise the agreement of MOND with observations in
light of the new results on the Cosmic Microwave Anisotropies provided by the
2003 flight of Boomerang. The measurements of the height of the third acoustic
peak, provided by several small scale CMB experiments have reached enough
sensitivity to severely constrain models without cold dark matter. Assuming
that acoustic peak structure in the CMB is unchanged and that local
measurements of the Hubble constant can be applied, we find that the cold dark
matter is strongly favoured with Bayesian probability ratio of about one in two
hundred.


title: Robustness of Discrete Flows and Caustics in Cold Dark Matter Cosmology

abstract:
  Although a simple argument implies that the distribution of dark matter in
galactic halos is characterized by discrete flows and caustics, their presence
is often ignored in discussions of galactic dynamics and of dark matter
detection strategies. Discrete flows and caustics can in fact be irrelevant if
the number of flows is very large. We estimate the number of dark matter flows
as a function of galactocentric distance and consider the various ways in which
that number can be increased, in particular by the presence of structure on
small scales (dark matter clumps) and the scattering of the flows by
inhomogeneities in the matter distribution. We find that, when all complicating
factors are taken into account, discrete flows and caustics in galactic halos
remain a robust prediction of cold dark matter cosmology with extensive
implications for observation and experiment.


title: A 2.1 Solar Mass Pulsar Measured by Relativistic Orbital Decay

abstract:
  PSR J0751+1807 is a millisecond pulsar in a circular 6 hr binary system with
a helium white dwarf secondary. Through high precision pulse timing
measurements with the Arecibo and Effelsberg radio telescopes, we have detected
the decay of its orbit due to emission of gravitational radiation. This is the
first detection of the relativistic orbital decay of a low-mass, circular
binary pulsar system. The measured rate of change in orbital period, corrected
for acceleration biases, is dP_b/dt=(-6.4+-0.9)x10^-14. Interpreted in the
context of general relativity, and combined with measurement of Shapiro delay,
it implies a pulsar mass of 2.1+-0.2 solar masses, the most massive pulsar
measured. This adds to the emerging trend toward relatively high neutron star
masses in neutron star--white dwarf binaries. Additionally, there is some
evidence for an inverse correlation between pulsar mass and orbital period in
these systems. We consider alternatives to the general relativistic analysis of
the data, and we use the pulsar timing data to place limits on violations of
the strong equivalence principle.


title: Transit Photometry of the Core-Dominated Planet HD 149026b

abstract:
  We report g, V, and r photometric time series of HD 149026 spanning predicted
times of transit of the Saturn-mass planetary companion, which was recently
discovered by Sato and collaborators. We present a joint analysis of our
observations and the previously reported photometry and radial velocities of
the central star. We refine the estimate of the transit ephemeris to Tc [HJD] =
2453527.87455^{+0.00085}_{-0.00091} + N * 2.87598^{+0.00012}_{-0.00017}.
Assuming that the star has a radius of 1.45 +/- 0.10 R_Sun and a mass of 1.30
+/- 0.10 M_Sun, we estimate the planet radius to be 0.726 +/- 0.064 R_Jup,
which implies a mean density of 1.07^{+0.42}_{-0.30} g/cm^3. This density is
significantly greater than that predicted for models which include the effects
of stellar insolation and for which the planet has only a small core of solid
material. Thus we confirm that this planet likely contains a large core, and
that the ratio of core mass to total planet mass is more akin to that of Uranus
and Neptune than that of either Jupiter or Saturn.


title: Observations of 51 Ophiuchi with MIDI at the VLTI

abstract:
  We present interferometric observations of the Be star 51 Ophiuchi. These
observations were obtained during the science demonstration phase of the MIDI
instrument at the Very Large Telescope Interferometer (VLTI). Using MIDI, a
Michelson 2 beam combiner that operates at the N band (8 to 13 microns), we
obtained for the first time observations of 51 Oph in the mid-infrared at
high-angular resolution. It is currently known that this object presents a
circumstellar dust and gas disk that shows a very different composition from
other Herbig Ae disks. The nature of the 51 Oph system is still a mystery to be
solved. Does it have a companion? Is it a protoplanetary system? We still don't
know. Observations with MIDI at the VLTI allowed us to reach high-angular
resolution (20 mas).We have several uv points that allowed us to constrain the
disk model. We have modeled 51 Oph visibilities and were able to constrain the
size and geometry of the 51 Oph circumstellar disk.


title: The dependence on environment of Cold Dark Matter Halo properties

abstract:
  High-resolution LCDM cosmological N-body simulations are used to study the
properties of galaxy-size dark halos in different environments (cluster, void,
and "field"). Halos in clusters and their surroundings have a median spin
parameter ~1.3 times lower, and tend to be more spherical and to have less
aligned internal angular momentum than halos in voids and the field. For halos
in clusters the concentration parameters decrease on average with mass with a
slope of ~0.1; for halos in voids these concentrations do not change with mass.
For masses <5 10^11 M_sh^-1, halos in clusters are on average ~30-40% more
concentrated and have ~2 times higher central densities than halos in voids.
When comparing only parent halos, the differences are less pronounced but they
are still significant. The Vmax-and Vrms-mass relations are shallower and more
scattered for halos in clusters than in voids, and for a given Vmax or Vrms,
the mass is smaller at z=1 than at z=0 in all the environments. At z=1, the
differences in the halo properties with environment almost dissapear,
suggesting this that the differences were stablished mainly after z~1. The
halos in clusters undergo more dramatic changes than those in the field or the
voids. The differences with environment are owing to (i) the dependence of halo
formation time on environment, and (ii) local effects as tidal stripping and
the tumultuos histories that halos suffer in high-density regions. We calculate
seminumerical models of disk galaxy evolution in halos with the properties
found for the different environments. For a given disk mass, the galaxy disks
have higher surface density, larger Vd,max and secular bulge-to-disk ratio,
lower gas fraction, and are redder as one goes from cluster to void
environments, in rough agreement with observations. (abridged)


title:
Star Formation in Isolated Disk Galaxies. II. Schmidt Laws and
  Efficiency of Gravitational Collapse

abstract:
  (Abridged). We model gravitational instability in a wide range of isolated
disk galaxies, using GADGET, a three-dimensional, smoothed particle
hydrodynamics code. The model galaxies include a dark matter halo and a disk of
stars and isothermal gas. The global Schmidt law observed in disk galaxies is
quantitatively reproduced by our models. We find that the surface density of
star formation rate directly correlates with the strength of local
gravitational instability. The local Schmidt laws of individual galaxies in our
models show clear evidence of star formation thresholds. Our results suggest
that the non-linear development of gravitational instability determines the
local and global Schmidt laws, and the star formation thresholds.


title:
Cassini UVIS Observations of the Io Plasma Torus. III. Observations of
  Temporal and Azimuthal Variability

abstract:
  In this third paper in a series presenting observations by the Cassini
Ultraviolet Imaging Spectrometer (UVIS) of the Io plasma torus, we show
remarkable, though subtle, spatio-temporal variations in torus properties. The
Io torus is found to exhibit significant, near-sinusoidal variations in ion
composition as a function of azimuthal position. The azimuthal variation in
composition is such that the mixing ratio of S II is strongly correlated with
the mixing ratio of S III and the equatorial electron density and strongly
anti-correlated with the mixing ratios of both S IV and O II and the equatorial
electron temperature. Surprisingly, the azimuthal variation in ion composition
is observed to have a period of 10.07 hours--1.5% longer than the System III
rotation period of Jupiter, yet 1.3% shorter than the System IV period defined
by Brown (1995). Although the amplitude of the azimuthal variation of S III and
O II remained in the range of 2-5%, the amplitude of the S II and S IV
compositional variation ranged between 5-25% during the UVIS observations.
Furthermore, the amplitude of the azimuthal variations of S II and S IV appears
to be modulated by its location in System III longitude, such that when the
region of maximum S II mixing ratio (minimum S IV mixing ratio) is aligned with
a System III longitude of ~200 +/- 15 degrees, the amplitude is a factor of ~4
greater than when the variation is anti-aligned. This behavior can explain
numerous, often apparently contradictory, observations of variations in the
properties of the Io plasma torus with the System III and System IV coordinate
systems.


title: The Cooling of Compact Stars

abstract:
  The cooling of a compact star depends very sensitively on the state of dense
matter at supranuclear densities, which essentially controls the neutrino
emission, as well as on the structure of the stellar outer layers which control
the photon emission. Open issues concern the hyperon population, the presence
of meson condensates, superfluidity and superconductivity, and the transition
of confined hadronic matter to quark matter. This paper describes these issues
and presents cooling calculations based on a broad collection of equations of
state for neutron star matter and strange matter. These results are tested
against the body of observed cooling data.


title:
On the Predicted and Observed Color Boundaries of the RR Lyrae
  Instability Strip as a Function of Metallicity

abstract:
  The purpose of the paper is to predict the temperature at the fundamental
blue edge (FBE) of the instability strip for RR Lyrae (RRL) variables from the
pulsation equation that relates temperature to period, luminosity, and mass.
Modern data for the correlations between period, luminosity, and metallicity at
the FBE for field and cluster RRL are used for the temperature calculation. The
predicted temperatures are changed to B-V colors using an adopted color
transformation. The predicted temperatures at the FBE become hotter as [Fe/H]
changes from 0 to -1.5, and thereafter cooler as the metallicity decreases to
-2.5 and beyond. The temperature range over this interval of metallicity is
$\Delta$log $T_e$ = 0.04, or 640 K at 6900K. The predicted color variation is
at the level of 0.03 mag in B-V. The predictions are compared with the observed
RRL colors at the FBE for both the field and cluster variables, showing general
agreement at the level of 0.02 mag in (B-V)$_o$, which, however, is the
uncertainty of the reddening corrections.
  The focus of the problem is then reversed by fitting a better envelope to the
observed FBE relation between color and metallicity for metallicities smaller
than -1.8 which, when inserted in the pulsation equation, gives a non-linear
calibration ....


title:
X-ray variability of NGC 3227 and NGC 5506 and the nature of AGN
  `states'

abstract:
  We use X-ray monitoring data obtained over a broad range of time-scales to
measure the broadband power spectral density functions (PSDs) of two Seyfert
galaxies, the broad line Seyfert 1 NGC 3227 and the Seyfert 2 NGC 5506, which
has recently been identified as an obscured Narrow Line Seyfert 1 (NLS 1).
Using a Monte-Carlo fitting technique we demonstrate that both PSDs are
reminiscent of the PSD of black hole X-ray binaries (BHXRBs) in the high/soft
state, and specifically rule out a low/hard state PSD shape in NGC 3227. This
result demonstrates that, at least where variability is concerned, broad line
Seyferts with hard X-ray spectra (photon index~1.6) are not simply the
analogues of the low/hard state in BHXRBs, and the dichotomy of NLS 1 and broad
line Seyferts cannot be simply interpreted in terms of the two states. We show
that the PSD normalisation in NGC 3227 is strongly energy dependent, with
larger variability amplitudes at lower energies, unlike NGC 5506 which shows
little energy-dependence of variability. We demonstrate that this difference is
caused by spectral pivoting of the continuum in NGC 3227 at high energies,
which is probably also related to the large amplitude of variability seen in
the 2-10 keV band in this AGN. Using the new PSD data and new results in the
literature, we replot the PSD break time-scale versus mass plot for all AGN
with PSD breaks measured so far, and demonstrate that higher accretion-rate AGN
appear to have relatively shorter break time-scales for their black hole mass
than lower-accretion rate AGN.


title:
Young stars and dust in AFGL437: NICMOS/HST polarimetric imaging of an
  outflow source

abstract:
  We present near infrared broad band and polarimetric images of the compact
star forming cluster AFGL437 obtained with the NICMOS instrument aboard HST.
Our high resolution images reveal a well collimated bipolar reflection
nebulosity in the cluster and allow us to identify WK34 as the illuminating
source. The scattered light in the bipolar nebulosity centered on this source
is very highly polarized (up to 79%). Such high levels of polarization implies
a distribution of dust grains lacking large grains, contrary to the usual dust
models of dark clouds. We discuss the geometry of the dust distribution giving
rise to the bipolar reflection nebulosity and make mass estimates for the
underlying scattering material. We find that the most likely inclination of the
bipolar nebulosity, south lobe inclined towards Earth, is consistent with the
inclination of the large scale CO molecular outflow associated with the
cluster, strengthening the identification of WK34 as the source powering it.


title: Blazars and the emerging AGN/black hole X-ray binary paradigm

abstract:
  We briefly review the emerging paradigm which links the radio-quiet and
radio-loud classes of AGN to the different accretion states observed in stellar
mass black hole X-ray binary systems (BHXRBs), and discuss the relevance of the
AGN/BHXRB connection to blazar variability.


title: A Morphological Study of Gamma-Ray Burst Host Galaxies

abstract:
  We present a comprehensive study of the morphological properties of 42
gamma-ray burst (GRB) host galaxies imaged with the Hubble Space Telescope in
the optical band. The purpose of this study is to understand the relation of
GRBs to their macro-environments, and to compare the GRB-selected galaxies to
other high redshift samples. We perform both qualitative and quantitative
analyses by categorizing the galaxies according to their visual properties, and
by examining their surface brightness profiles. We find that all of the
galaxies have approximately exponential profiles, indicative of galactic disks,
and have a median scale length of about 1.7 kpc. Inspection of the visual
morphologies reveals a high fraction of merging and interacting systems, with
\~30% showing clear signs of interaction, and an additional ~30% exhibiting
irregular and asymmetric structure which may be the result of recent mergers;
these fractions are independent of redshift and galaxy luminosity. On the other
hand, the three GRB host galaxies for which submillimeter and radio emission
has been detected are isolated and compact, unlike the luminous
submillimeter-selected galaxies. The fraction of mergers appears to be elevated
compared to other high redshift samples, particularly for the low luminosities
of GRB hosts (M_B ~ -16 to -21 mag). This suggests that merging and interacting
galaxies undergoing a burst of star formation may be an efficient site for the
production of GRB progenitors. Finally, we show that GRB hosts clearly follow
the size-luminosity relation present in other galaxy samples, but thanks to
absorption redshifts they help extend this relation to lower luminosities.


title:
Detection of neutral hydrogen in early-type dwarf galaxies of the
  Sculptor Group

abstract:
  We present our results of deep 21 cm line (HI) observations of five early and
mixed-type dwarf galaxies in the nearby Sculptor group using the ATNF 64m
Parkes Radio Telescope. Four of these objects, ESO294-G010, ESO410-G005,
ESO540-G030, and ESO540-G032, were detected in HI with neutral hydrogen masses
in the range of 2-9x10^5 M_{\odot} ($M_{HI}/L_{B}$ = 0.08, 0.13, 0.16, and
0.18, respectively). These HI masses are consistent with the gas mass expected
from stellar outflows over a large period of time. Higher resolution radio data
from the Australia Telescope Compact Array were further analysed to measure
more accurate positions and the distribution of the HI gas. In the cases of
dwarfs ESO294-G010 and ESO540-G030, we find significant offsets of 290 pc and
460 pc, respectively, between the position of the HI peak flux and the center
of the stellar component. These offsets are likely to have internal cause such
as the winds from star-forming regions. The fifth object, the spatially
isolated dwarf elliptical Scl-dE1, remains undetected at our 3\sigma limit of
22.5 mJy km/s and thus must contain less than 10^5 M_{\odot} of neutral
hydrogen. This leaves Scl-dE1 as the only Sculptor group galaxy known where no
interstellar medium has been found to date. The object joins a list of similar
systems including the Local Group dwarfs Tucana and Cetus that do not fit into
the global picture of the morphology-density relation where gas-rich dwarf
irregulars are in relative isolation and gas-deficient dwarf ellipticals are
satellites of more luminous galaxies.