title: Stellar Populations in Nearby Lenticular Galaxies

abstract:
  We have obtained 2D spectral data for a sample of 58 nearby S0 galaxies with
the Multi-Pupil Spectrograph of the 6m telescope of the Special Astrophysical
Observatory of the Russian Academy of Sciences. The Lick indices H-beta, Mgb,
and <Fe> are calculated separately for the nuclei and for the bulges taken as
the rings between R=4" and 7"; and the luminosity-weighted ages, metallicities,
and Mg/Fe ratios of the stellar populations are estimated by confronting the
data to SSP models. Four types of galaxy environments are considered: clusters,
centers of groups, other places in groups, and field. The nuclei are found to
be on average slightly younger than the bulges in any types of environments,
and the bulges of S0s in the sparse environments are younger than those in the
dense environments. The effect can be partly attributed to the well-known age
correlation with the stellar velocity dispersion in early-type galaxies (in our
sample the galaxies in sparse environements are on average less massive than
those in dense environments). However for the most massive S0s, with the
stellar velocity dispersion of 170-220 km/s, the age dependence on the
environment is still significant at the confidence level of 1.5 sigma.


title: Submillimeter emission from the hot molecular jet HH 211

abstract:
  We observed the HH 211 jet in the submillimeter continuum and the CO(3-2) and
SiO(8-7) transitions with the Submillimeter Array. The continuum source
detected at the center of the outflow shows an elongated morphology,
perpendicular to the direction of the outflow axis. The high-velocity emission
of both molecules shows a knotty and highly collimated structure. The SiO(8-7)
emission at the base of the outflow, close to the driving source, spans a wide
range of velocities, from -20 up to 40 km s^{-1}. This suggests that a
wide-angle wind may be the driving mechanism of the HH 211 outflow. For
distances greater than 5" (1500 AU) from the driving source, emission from both
transitions follows a Hubble-law behavior, with SiO(8-7) reaching higher
velocities than CO(3-2), and being located upstream of the CO(3-2) knots. This
indicates that the SiO(8-7) emission is likely tracing entrained gas very close
to the primary jet, while the CO(3-2) is tracing less dense entrained gas. From
the SiO(5-4) data of Hirano et al. we find that the SiO(8-7)/SiO(5-4)
brightness temperature ratio along the jet decreases for knots far from the
driving source. This is consistent with the density decreasing along the jet,
from (3-10)x10^6 cm^{-3} at 500 AU to (0.8-4)x10^6 cm^{-3} at 5000 AU from the
driving source.


title: Studying distant dwarf galaxies with GEMS and SDSS

abstract:
  We study the colors, structural properties, and star formation histories of a
sample of ~1600 dwarfs over look-back times of ~3 Gyr (z=0.002-0.25). The
sample consists of 401 distant dwarfs drawn from the Galaxy Evolution from
Morphologies and SEDs (GEMS) survey, which provides high resolution Hubble
Space Telescope (HST) Advanced Camera for Surveys (ACS) images and accurate
redshifts, and of 1291 dwarfs at 10-90 Mpc compiled from the Sloan Digitized
Sky Survey (SDSS). We find that the GEMS dwarfs are bluer than the SDSS dwarfs,
which is consistent with star formation histories involving starbursts and
periods of continuous star formation. The full range of colors cannot be
reproduced by single starbursts or constant star formation alone. We derive the
star formation rates of the GEMS dwarfs and estimate the mechanical
luminosities needed for a complete removal of their gas. We find that a large
fraction of luminous dwarfs are likely to retain their gas, whereas fainter
dwarfs are susceptible to a significant gas loss, if they would experience a
starburst.


title:
Chandra Observations of A2670 and A2107: A Comet Galaxy and cDs with
  Large Peculiar Velocities

abstract:
  We present an analysis of Chandra observations of the galaxy clusters A2670
and A2107. Their cD galaxies have large peculiar velocities (>200km/s) and thus
the clusters appear to be undergoing mergers. In A2670, we find a comet-like
structure around one of the brightest galaxies. At the leading edge of the
structure, there is a cold front. The mass of the X-ray gas in the comet-like
structure suggests that the galaxy was in a small cluster or group, and its
intracluster medium (ICM) is being stripped by ram-pressure. The regions of
cool interstellar medium (ISM) of the cD galaxies in A2670 and A2107 are very
compact. This is similar to the brightest galaxies in the Coma cluster, which
is also a merging cluster. In each galaxy, the short cooling time of the ISM
requires a heating source; the compact nature of the ISM makes it unlikely that
the heating source is a central active galactic nucleus (AGN).


title: Approximate dynamics of dark matter ellipsoids

abstract:
  The collapse of non-collisional dark matter and the formation of pancake
structures in the Universe are investigated approximately. Collapse is
described by a system of ordinary differential equations, in the model of a
uniformly rotating, three-axis, uniform density ellipsoid. Violent relaxation,
mass and angular momentum losses are taken into account phenomenologically. The
formation of the equilibrium configuration, secular instability and the
transition from a spheroid to a three-axis ellipsoid are investigated
numerically and analytically in this dynamical model.


title: Modeling the Warm Absorber in AGN

abstract:
  We present a wide grid of models for the structure and transmission
properties of warm absorbers in active galactic nuclei (AGN). Contrary to
commonly used constant density models, our absorbing cloud is assumed to be
under constant total (gas plus radiation) pressure. This assumption implies the
coexistence of material at different temperatures and ionization states, which
is a natural consequence of pressure and thermal equilibrium. Our
photoionization code allows us to compute the profiles of the density, the
temperature, the gas pressure, the radiation pressure and the ionization state
across the cloud, and to calculate the radiative transfer of continuum and
lines including Compton scattering. Therefore, equivalent widths of both
saturated and unsaturated lines are properly modeled. For each pair of the
incident spectrum slope and the ionization parameter at the cloud surface there
is a natural upper limit to the total column densities of the cloud due to
thermal instabilities. These maximum values are comparable to the observational
constraints on the column density of warm absorbers which may give support to
constant total pressure models. In all models we note considerable absorption
around 6.4 keV which modifies the intrinsic relativistically broadened iron
line profile originating in an accretion disk illuminated atmosphere. Our
models can be applied to fitting the spectroscopic data from the {\it
XMM-Newton} and {\it Chandra} satellites.


title: Nonaxisymmetric Magnetorotational Instability in Proto-Neutron Stars

abstract:
  We investigate the stability of differentially rotating proto-neutron stars
(PNSs) with a toroidal magnetic field. Stability criteria for nonaxisymmetric
MHD instabilities are derived using a local linear analysis. PNSs are expected
to have much stronger radial shear in the rotation velocity compared to normal
stars. We find that nonaxisymmetric magnetorotational instability (NMRI) with a
large azimuthal wavenumber $m$ is dominant over the kink mode ($m=1$) in
differentially rotating PNSs. The growth rate of the NMRI is of the order of
the angular velocity $\Omega$ which is faster than that of the kink-type
instability by several orders of magnitude. The stability criteria are
analogous to those of the axisymmetric magnetorotational instability with a
poloidal field, although the effects of leptonic gradients are considered in
our analysis. The NMRI can grow even in convectively stable layers if the
wavevectors of unstable modes are parallel to the restoring force by the
Brunt-V\"ais\"al\"a oscillation. The nonlinear evolution of NMRI could amplify
the magnetic fields and drive MHD turbulence in PNSs, which may lead to
enhancement of the neutrino luminosity.


title:
The Homogeneity of Interstellar Elemental Abundances in the Galactic
  Disk

abstract:
  We present interstellar elemental abundance measurements derived from Space
Telescope Imaging Spectrograph echelle observations of 47 sight lines extending
up to 6.5 kpc through the Galactic disk. These paths probe a variety of
interstellar environments, covering ranges of nearly four orders of magnitude
in molecular hydrogen fraction f(H_2) and more than two in mean hydrogen sight
line density <n_H>. Coupling the current data with Goddard High Resolution
Spectrograph data from 17 additional sight lines and the corresponding Far
Ultraviolet Spectroscopic Explorer and Copernicus observations of H_2
absorption features, we explore magnesium, phosphorus, manganese, nickel,
copper, and germanium gas-phase abundance variations as a function of <n_H>:
density-dependent depletion is noted for each element, consistent with a smooth
transition between two abundance plateaus identified with warm and cold neutral
interstellar medium depletion levels. The observed scatter with respect to an
analytic description of these transitions implies that total elemental
abundances are homogeneous on length scales of hundreds of parsecs, to the
limits of abundance measurement uncertainty. The probable upper limit we
determine for intrinsic variability at any <n_H> is 0.04 dex, aside from an
apparent 0.10 dex deficit in copper (and oxygen) abundances within 800 pc of
the Sun. Magnesium dust abundances are shown to scale with the amount of
silicon in dust and, in combination with a similar relationship between iron
and silicon, these data appear to favor the young F and G star values of Sofia
& Meyer (2001; ApJ 554, L221) as an elemental abundance standard for the
Galaxy.


title:
Spectral Variability of Quasars in the Sloan Digital Sky Survey. II: The
  C IV Line

abstract:
  We examine the variability of the high-ionizaton C IV line in a sample of 105
quasars observed at multiple epochs by the Sloan Digital Sky Survey. We find a
strong correlation between the change in the C IV line flux and the change in
the line width, but no correlations between the change in flux and changes in
line center and skewness. The relation between line flux change and line width
change is consistent with a model in which a broad line base varies with
greater amplitude than the line core. The objects studied here are more
luminous and at higher redshift than those normally studied for variability,
ranging in redshift from 1.65 to 4.00 and in absolute r-band magnitude from
roughly -24 to -28. Using moment analysis line-fitting techniques, we measure
line fluxes, centers, widths and skewnesses for the C IV line at two epochs for
each object. The well-known Baldwin Effect is seen for these objects, with a
slope beta = -0.22. The sample has a median intrinsic Baldwin Effect slope of
beta = -0.85; the C IV lines in these high-luminosity quasars appear to be less
responsive to continuum variations than those in lower luminosity AGN.
Additionally, we find no evidence for variability of the well known blueshift
of the C IV line with respect to the low-ionization Mg II line in the highest
flux objects, indicating that this blueshift might be useful as a measure of
orientation.


title:
The effect of a strong external radiation field on protostellar
  envelopes in Orion

abstract:
  We discuss the effects of an enhanced interstellar radiation field (ISRF) on
the observables of protostellar cores in the Orion cloud region. Dust radiative
transfer is used to constrain the envelope physical structure by reproducing
SCUBA 850 micron emission. Previously reported 13CO, C17O and H2CO line
observations are reproduced through detailed Monte Carlo line radiative
transfer models. It is found that the 13CO line emission is marginally
optically thick and sensitive to the physical conditions in the outer envelope.
An increased temperature in this region is needed in order to reproduce the
13CO line strengths and it is suggested to be caused by a strong heating from
the exterior, corresponding to an ISRF in Orion 10^3 times stronger than the
"standard" ISRF. The typical temperatures in the outer envelope are higher than
the desorption temperature for CO. The C17O emission is less sensitive to this
increased temperature but rather traces the bulk envelope material. The data
are only fit by a model where CO is depleted, except in the inner and outermost
regions where the temperature increases above 30-40 K. The fact that the
temperatures do not drop below approximately 25 K in any of the envelopes
whereas a significant fraction of CO is frozen-out suggest that the
interstellar radiation field has changed through the evolution of the cores.
The H2CO lines are successfully reproduced in the model of an increased ISRF
with constant abundances of 3-5x10^{-10}.


title: Polarization intermittency in MHD and its influence on turbulent cascade

abstract:
  Goldreich-Sridhar model of incompressible turbulence provides an elegant
approach to describing strong MHD turbulence. It relies on the fact that
interacting Alfvenic waves are independent and have random polarization.
However, in case of strong interaction a spontaneous local assymetry can arise.
We used direct numerical simulations to show that polarization alignment occurs
and it grows larger at smaller scales. This effect would lead to a shallower
spectrum and stronger anisotropy. Even small changes in these two properties
will have important astrophysical consequencies, e.g. for the cosmic ray
physics.


title:
Interaction of ultra-energetic cosmic neutrinos with a thermal gas of
  relic neutrinos

abstract:
  We use the formalism of finite-temperature field theory to study the
interactions of ultra-high energy (UHE) cosmic neutrinos with the thermal
background of relic neutrinos. From the imaginary part of the neutrino
self-energy, calculated in terms of the Z boson propagator near the resonance,
we derive general expressions for the UHE neutrino transmission probability.
This allows us to take into account the thermal effects introduced by the
momentum distribution of the relic neutrinos. We compare our results with the
approximate expressions existing in the literature and discuss the influence of
thermal effects on the absorption dips in the context of realistic UHE neutrino
fluxes and favoured neutrino mass schemes.


title:
Beryllium in Disk and Halo Stars -- Evidence for a Beryllium Dispersion
  in Old Stars

abstract:
  The study of Be in stars of differing metal content can elucidate the
formation mechanisms and the Galactic chemical evolution of Be. We have
obtained high-resolution, high signal-to-noise spectra of the resonance lines
of Be II in eight stars with the high-dispersion spectrograph (HDS) on the
Subaru 8.2 m telescope on Mauna Kea. Abundances of Be have been determined
through spectrum synthesis. The stars with [Fe/H] values > -1.1 conform to the
published general trend of Be vs Fe. We have confirmed the high Be abundance in
HD 94028 and have found a similarly high Be abundance in another star, HD
132475, at the same metallicity: [Fe/H] = -1.5. These two stars are 0.5 - 0.6
dex higher in Be than the Be-Fe trend. While that general trend contains the
evidence for a Galaxy-wide enrichment in Be and Fe, the higher Be abundances in
those two stars indicates local Be enrichments. Possible enrichment mechanisms
include hypernovae and multiple supernova explosions contained in a
superbubble. The star G 64-37 has [Fe/] = -3.2; we have determined its Be
abundance to look for evidence of a Be plateau. It's Be abundance appears to
extend the Be-Fe trend to lower Fe abundances without any evidence for a
plateau as had been indicated by a high Be abundance in another very metal-poor
star, G 64-12. Although these two stars have similar Be abundances within the
errors, it could be that their different Be values may be indicating that a Be
dispersion exists even at the lowest metallicities.


title:
Effect of the length of inflation on angular TT and TE power spectra in
  power-law inflation

abstract:
  The effect of the length of inflation on the power spectra of scalar and
tensor perturbations is estimated using the power-law inflation model with a
scale factor of a(t) = t^q. Considering various pre-inflation models with
radiation-dominated or scalar matter-dominated periods before inflation in
combination with two matching conditions, the temperature angular power
spectrum (TT) and temperature-polarization cross-power spectrum (TE) are
calculated and a likelihood analysis is performed. It is shown that the
discrepancies between the Wilkinson Microwave Anisotropy Probe (WMAP) data and
the LCDM model, such as suppression of the spectrum at l = 2,3 and oscillatory
behavior, may be explained by the finite length of inflation model if the
length of inflation is near 60 e-folds and q > 300. The proposed models retain
similar values of chi^2 to that achieved by the LCDM model with respect to fit
to the WMAP data, but display different characteristics of the angular TE power
spectra at l < 20.


title: HD 178892 - a cool Ap star with extremely strong magnetic field

abstract:
  We report a discovery of the Zeeman resolved spectral lines, corresponding to
the extremely large magnetic field modulus <Bs>=17.5 kG, in the cool Ap star HD
178892. The mean longitudinal field of this star reaches 7.5 kG, and its
rotational modulation implies the strength of the dipolar magnetic component
Bp>=23 kG. We have revised rotation period of the star using the All Sky
Automated Survey photometry and determined P=8.2478 d. Rotation phases of the
magnetic and photometric maxima of the star coincide with each other. We
obtained Geneva photometric observation of HD 178892 and estimated
Teff=7700+/-250 K using photometry and the hydrogen Balmer lines. Preliminary
abundance analysis reveals abundance pattern typical of rapidly oscillating Ap
stars.


title:
The Element Abundances in Bare Planetary Nebula Central Stars and the
  Shell Burning in AGB Stars

abstract:
  We review the observed properties of extremely hot hydrogen-deficient
post-AGB stars of spectral type [WC] and PG1159. Their H-deficiency is probably
caused by a (very) late helium-shell flash or a AGB final thermal pulse, laying
bare interior stellar regions which are usually kept hidden below the hydrogen
envelope. Thus, the photospheric element abundances of these stars allow to
draw conclusions about details of nuclear burning and mixing processes in the
precursor AGB stars. We summarize the state-of-the-art of stellar evolution
models which simulate AGB evolution and the occurrence of a late He-shell
flash. We compare predicted element abundances to those determined by
quantitative spectral analyses performed with advanced non-LTE model
atmospheres. A good qualitative and quantitative agreement is found. Future
work can contribute to an even more complete picture of the nuclear processes
in AGB stars.


title:
Mapping Large-Scale Structures Behind the Galactic Plane: The Second
  CIZA Subsample

abstract:
  We present the latest results of the Clusters in the Zone of Avoidance (CIZA)
survey, which is mapping the large-scale matter distribution behind the Milky
Way by performing the first systematic search for X-ray luminous galaxy
clusters at low Galactic latitudes. The survey's approach, which uses X-ray
emission to locate cluster candidates, overcomes the problems faced by
optically selected cluster surveys which have traditionally avoided this region
of the sky due to the severe extinction present along the Galactic plane. We
here present the second flux-limited CIZA cluster catalog containing 60 X-ray
luminous galaxy clusters, 88% of which are new discoveries. We also examine the
degree to which known superclusters extend into the Zone of Avoidance and
highlight newly discovered structures which have previously gone unnoticed. We
show that the survey has found far fewer rich clusters in the Great Attractor
region than would be expected given the region's proposed mass. Instead, we
find a significant increase in the number of clusters behind the Great
Attractor, with the most notable being an association of clusters near the
Shapley supercluster. We propose these clusters trace an extension of the
large-scale filament network in which the Shapley concentration is embedded. We
also highlight an association of clusters near the Galactic anticenter, which
is the first supercluster found to be completely hidden by the Milky Way. Our
finding of a less massive Great Attractor and the detection of significant
structures behind the complex supports studies which suggest the motion of
nearby galaxies, including that of the Local Group, is due, in part, to a
large-scale bulk flow which is induced by overdensities beyond the Great
Attractor region.


title: Spectroscopic companions of very young brown dwarfs

abstract:
  I review here the results of the first RV survey for spectroscopic companions
to very young brown dwarfs (BDs) and (very) low-mass stars in the ChaI
star-forming cloud with UVES at the VLT. This survey studies the binary
fraction in an as yet unexplored domain not only in terms of primary masses
(substellar regime) and ages (a few Myr) but also in terms of companion masses
(sensitive down to planetary masses) and separations (< 1 AU). The UVES spectra
obtained so far hint at spectroscopic companions of a few Jupiter masses around
one BD and around one low-mass star (M4.5) with orbital periods of at least
several months. Furthermore, the data indicate a multiplicity fraction
consistent with field BDs and stellar binaries for periods < 100 days.


title: You Can't Get There From Here: Hubble Relaxation in the Local Volume

abstract:
  A beginning end-point for galaxy motions within the 10-Mpc Local Volume is
constructed by requiring a smooth distribution of (luminous) mass at the time
of recombination, which is shown to be equivalent to a smooth Hubble flow at
early times. It is found, by this purely kinematical method, that present
peculiar motions are too small by a factor of at least several (and largely in
the wrong direction) to have produced the observed structures within the age of
the universe. Known dynamical effects are inadequate to remove the discrepancy.
This result is different in origin from previously known ``cold flow''
problems. The simple dynamical picture often used within the Local Volume (for
instance, in deriving masses through calculation of a zero-velocity surface) is
thus called into question. The most straightforward explanation (though not the
only possible) is that there exists a large quantity of baryonic matter in this
region so far undetected, and unassociated with galaxies or groups.


title: A Note on the Cosmic Evolution of the Axion in a Strong Magnetic Field

abstract:
  It has been pointed out in the literature that in the presence of an external
magnetic field the axion mass receives an electromagnetic contribution. We show
that if a magnetic field with energy density larger than ~10^{-8} times the
energy density of the Universe existed at temperatures of a few GeV, that
contribution would be dominant and consequently the cosmic evolution of the
axion field would change substantially. In particular, the expected axion relic
abundance would be lowered, allowing a small relaxation of the present
cosmological bound on the Peccei-Quinn constant.


title: Simulating Wide-Field Quasar Surveys from the Optical to Near-Infrared

abstract:
  A number of deep, wide-field, near-infrared surveys employing new infrared
cameras on 4m-class telescopes are about to commence. These surveys have the
potential to determine the fraction of luminous dust-obscured quasars that may
have eluded surveys undertaken at optical wavelengths. In order to understand
the new observations it is essential to make accurate predictions of surface
densities and number-redshift relations for unobscured quasars in the
near-infrared based on information from surveys at shorter wavelengths. The
accuracy of the predictions depends critically on a number of key components.
The commonly used single power-law representation for quasar SEDs is inadequate
and the use of an SED incorporating the upturn in continuum flux at
lambda~12000 A is essential. The presence of quasar host galaxies is
particularly important over the restframe wavelength interval 8000 < lambda <
16000 A and we provide an empirical determination of the magnitude distribution
of host galaxies using a low redshift sample of quasars from the SDSS DR3
quasar catalogue. A range of models for the dependence of host galaxy
luminosity on quasar luminosity is investigated, along with the implications
for the near-infrared surveys. Even adopting a conservative model for the
behaviour of host galaxy luminosity the number counts for shallow surveys in
the K-band increase by a factor of two. The degree of morphological selection
applied to define candidate quasar samples in the near-infrared is found to be
an important factor in determining the fraction of the quasar population
included in such samples.


title:
On the metallicity dependence of the winds from red supergiants and
  Asymptotic Giant Branch stars

abstract:
  Over much of the initial mass function, stars are destined to become luminous
and cool red giants. They may then be able to produce dust in an atmosphere
which has been elevated by strong radial pulsations, and hence drive a wind.
The amount of mass that is lost in this way can be a very significant fraction
of the stellar mass, and especially in the case of intermediate-mass stars it
is highly enriched. The delay between a star's birth and its feedback into the
environment varies from several million years for massive stars to almost the
age of the Universe for the least massive red giants we see today. I here
present a review on the metallicity dependence of red giant winds. I show that
recent measurements not only confirm theoretical expectations, but also
admonish of common misconceptions with implications for feedback at low initial
metallicity.


title: Laboratory tests on dark energy

abstract:
  The physical nature of the currently observed dark energy in the universe is
completely unclear, and many different theoretical models co-exist.
Nevertheless, if dark energy is produced by vacuum fluctuations then there is a
chance to probe some of its properties by simple laboratory tests based on
Josephson junctions. These electronic devices can be used to perform `vacuum
fluctuation spectroscopy', by directly measuring a noise spectrum induced by
vacuum fluctuations. One would expect to see a cutoff near 1.7 THz in the
measured power spectrum, provided the new physics underlying dark energy
couples to electric charge. The effect exploited by the Josephson junction is a
subtile nonlinear mixing effect and has nothing to do with the Casimir effect
or other effects based on van der Waals forces. A Josephson experiment of the
suggested type will now be built, and we should know the result within the next
3 years.


title:
The evolution of Radio Loud Quasar host galaxies: AO observations at z =
  3

abstract:
  We report on ESO--VLT adaptive optics imaging of one radio-loud quasar at z
$\sim$ 3. In spite of the large distance of the object we are able to detect
its surrounding extended nebulosity the properties of which are consistent with
an underlying massive galaxy of M$_K$ $\sim$ --27 and effective radius R$_e$ =
7 kpc. As far as we know this is the clearest detection of a radio loud quasar
host at high redshift. The host luminosity is indicative of the existence of
massive spheroids even at this early cosmic epoch. The host luminosity is about
1 magnitude fainter than the expected value based on the average trend of the
host galaxies of RLQ at lower redshift. The result, which however is based on a
single object, suggests that at z $\sim$ 3 there is a deviation from a
luminosity--redshift dependence regulated only by passive evolution.


title:
Approaching the knee -- balloon-borne observations of cosmic ray
  composition

abstract:
  Below the knee in the cosmic ray spectrum, balloon and spacecraft experiments
offer the capability of direct composition and energy measurements on the
primary particles. A major difficulty is obtaining enough exposure to extend
the range of direct measurements sufficiently high in energy to permit overlap
with ground-based observations. Presently, balloon and space measurements
extend only up to ~100 TeV, well below the range of ground-based experiments.
The prospect of Ultra-Long Duration Balloon missions offers the promise of
multiple long flights that can build up exposure. The status of balloon
measurements to measure the high energy proton and nuclear composition and
spectrum is reviewed, and the statistical considerations involved in searching
for a steepening in the spectrum are discussed. Given the very steeply falling
spectrum, it appears unlikely that balloon experiments will be able to extend
the range of direct measurements beyond 1000 TeV any time in the near future.
Especially given the recent suggestions from KASCADE that the proton spectrum
steepens only at 4000-5000 TeV, the chance of detecting the knee with direct
measurements of protons to iron on balloons is not likely to occur without
significant increases in the payload and flight duration capabilities of high
altitude balloons.


title:
Early Evolution of Stellar Groups and Clusters: Environmental Effects on
  Forming Planetary Systems

abstract:
  This paper studies the dynamical evolution of young stellar clusters with $N$
= 100 - 1000 members. We use N-body simulations to explore how evolution
depends on system size $N$ and the initial conditions. Motivated by recent
observations of extremely young systems, this study compares subvirial and
virial starting states. Multiple realizations of equivalent cases (100
simulations per case) are used to build up a robust statistical description of
these systems, e.g., distributions of closest approaches, mass profiles, and
distributions of radial locations. These results provide a framework from which
to assess the effects of these clusters on star and planet formation. The
distributions of radial positions are used in conjunction with distributions of
FUV luminosities (also calculated here) to determine the radiation exposure of
circumstellar disks. The distributions of closest approaches are used in
conjunction with scattering cross sections (calculated here from $10^5$
scattering experiments) to determine the probability of solar system
disruption. We also use the nearby cluster NGC 1333 as a test case. Our main
conclusion is that clusters in this size range have only a modest effect on
forming planetary systems: Interaction rates are low so that the typical solar
system experiences a single encounter within 1000 AU. Radiation exposure is
low, with median FUV flux $G_0$ = 900, so that photoevaporation of disks is
only important beyond 30 AU. Given the low interaction rates and modest
radiation levels, we suggest that solar system disruption is a rare event in
these clusters.


title: On the origin and excitation of the extended nebula surrounding NGC 1275

abstract:
  We use line-of-sight velocity information on the filamentary emission-line
nebula of NGC 1275 to infer a dynamical model of the nebula's flow through the
surrounding intracluster gas. We detect outflowing gas and flow patterns that
match simulations of buoyantly rising bubbles from which we deduce that some of
the nebula filaments have been drawn out of NGC 1275. We find a radial gradient
of the ratio [NII]6584/H-alpha which may be due to a variation in metallicity,
interactions with the surrounding intracluster medium or a hardening of the
excitation mechanism. We find no preferred spatial correlation of stellar
clusters within the filaments and there is a notable lack of [OIII]5007
emission, therefore it is unlikely that the filaments are ionized by stellar
UV.


title: Evolution of the fine-structure constant in the non-linear regime

abstract:
  We study the evolution of the fine-structure constant, $\alpha$, induced by
non-linear density perturbations in the context of the simplest class of
quintessence models with a non-minimal coupling to the electromagnetic field,
in which the two available free functions (potential and gauge kinetic
function) are Taylor-expanded up to linear order. We show that the results
obtained using the spherical infall model for an infinite wavelength
inhomogeneity are inconsistent with the results of a local linearized gravity
study and we argue in favour of the second approach. We also discuss recent
claims that the value of $\alpha$ inside virialised regions could be
significantly different from the background one on the basis of these findings.


title:
Strong limits on the possible decay of the vacuum energy into CDM or CMB
  photons

abstract:
  We investigate models that suggest that the vacuum energy decays into cold
dark matter (CDM) and into a homogeneous distribution of a thermalized cosmic
microwave background (CMB), which is characteristic of an adiabatic vacuum
energy decay into photons. We show that the density fluctuation spectrum
obtained from the CMB and galaxy distribution data agreement put strong limits
on the rate of decay of the vacuum energy. A vacuum energy decaying into CDM
increases its total density \rho, diluting (\delta \rho/\rho)^2. The observed
temperature fluctuations of the CMB photons (\delta T/T)^2 are approximately
proportional to CDM density fluctuations (\delta \rho/\rho)^2. In both case,
when evaluating (\delta \rho/\rho)^2 at the recombination era, its present
measured value must be increased by a factor F. Since the (\delta \rho/\rho)^2
derived from the CMB and galaxy distribution data agree to \sim 10%, the
maximum value for F is F_{\rm max}\aprox 1.1. Our results indicate that the
rate of the decay of the vacuum energy into CDM and CMB photons are extremely
small.


title: 26Al in the inner Galaxy

abstract:
  We performed a spectroscopic study of the 1809 keV gamma-ray line from 26Al
decay in the Galaxy using the SPI imaging spectrometer with its high-resolution
Ge detector camera on the INTEGRAL observatory. We analyzed observations of the
first two mission years, fitting spectra from all 7130 telescope pointings in
narrow energy bins to models of instrumental background and the 26Al sky.
Instrumental background is estimated from independent tracers of cosmic-ray
activation. The shape of the 26Al signal is compared to the instrumental
response to extract the width of the celestial line. We detect the 26Al line at
\~16sigma significance. The line is broadened only slightly, if at all; we
constrain the width to be below 2.8 keV (FWHM, 2 sigma). The average Doppler
velocities of 26Al at the time of its decay in the interstellar medium (decay
time~1.04 My) therefore are probably around 100 km/s, in agreement with
expectations from Galactic rotation and interstellar turbulence. The flux and
spatial distribution of the emission are found consistent with previous
observations. The derived amount of 26Al in the Galaxy is 2.8 (+/-0.8) M_solar.


title: Angular Differential Imaging: a Powerful High-Contrast Imaging Technique

abstract:
  Angular differential imaging is a high-contrast imaging technique that
reduces quasi-static speckle noise and facilitates the detection of nearby
companions. A sequence of images is acquired with an altitude/azimuth telescope
while the instrument field derotator is switched off. This keeps the instrument
and telescope optics aligned and allows the field of view to rotate with
respect to the instrument. For each image, a reference PSF is constructed from
other appropriately-selected images of the same sequence and subtracted to
remove quasi-static PSF structure. All residual images are then rotated to
align the field and are combined. Observed performances are reported for Gemini
North data. It is shown that quasi-static PSF noise can be reduced by a factor
\~5 for each image subtraction. The combination of all residuals then provides
an additional gain of the order of the square root of the total number of
acquired images. A total speckle noise attenuation of 20-50 is obtained for
one-hour long observing sequences compared to a single 30s exposure. A PSF
noise attenuation of 100 was achieved for two-hour long sequences of images of
Vega, reaching a 5-sigma contrast of 20 magnitudes for separations greater than
8". For a 30-minute long sequence, ADI achieves 30 times better signal-to-noise
than a classical observation technique. The ADI technique can be used with
currently available instruments to search for ~1MJup exoplanets with orbits of
radii between 50 and 300 AU around nearby young stars. The possibility of
combining the technique with other high-contrast imaging methods is briefly
discussed.


title: Inflation without inflatons

abstract:
  (abridged)We present a model which predicts inflation without the presence of
inflaton fields, based on the \epsilon R^2 and Starobinsky models. It links the
above models to the observable universe, in particular, to the ratio r of
tensor to scalar fluctuations. In our model, we assume the existence of
particles with the mass M that have a long decay time. These particles which
were gravitationally produced \sim 60e-folds before the end of inflation
produced the nearly scale invariant scalar density fluctuations which are
observed. Gravitational waves (tensor fluctuations) were also produced at this
epoch. The ratio of tensor to scalar fluctuations r (which are to be measured
in the near future to good accuracy) determines M, which together with H_0,
determine the time at the end of inflation, t_end. At t_end, the Hubble
parameter begins to oscillate rapidly, gravitationally producing the bulk of
the M particles, which we identify with the matter content of the universe
today. The time required for the universe to dissipate its vacuum energy into M
particles is found to be t_dis \simeq 6M_Pl^2/M^3. We assume that the time
t_RH, (called the reheating time) needed for the M particles to decay into
relativistic particles, is very much greater than that necessary to create the
M particles, t_dis. From the ratio f\equiv t_dis/t_RH and g_\ast (the total
number of degrees of freedom of the relativistic particles) we can, then,
evaluate the maximum temperature of the universe, T_max, and the reheat
temperature, T_RH, at t_RH. Our model, thus, predicts M, t_dis, t_end, T_max,
T_RH, t_max, and t_RH as a function of r, f, and g_\ast (and to a weaker extent
the particle content of the vacuum near the Planck epoch).


title:
Coherent radio pulses from showers in different media: A unified
  parameterization

abstract:
  We study the frequency and angular dependences of Cherenkov radio pulses
originated by the excess of electrons in electromagnetic showers in different
dense media. We develop a simple model to relate the main characteristics of
the electric field spectrum to the properties of the shower such as
longitudinal and lateral development. This model allows us to establish the
scaling of the electric field spectrum with the properties of the medium such
as density, radiation length, Moliere radius, critical energy and refraction
index. We normalize the predictions of the scaling relations to the numerical
results obtained in our own developed GEANT4-based Monte Carlo simulation, and
we give a unified parameterization of the frequency spectrum and angular
distribution of the electric field in ice, salt, and the lunar regolith, in
terms of the relevant properties of the media. Our parameterizations are valid
for electromagnetic showers below the energy at which the
Landau-Pomeranchuk-Migdal effect starts to be relevant in these media. They
also provide an approximate estimate of radio emission in hadronic showers
induced by high energy cosmic rays or neutrinos.


title:
Chandra Multiwavelength Project: Normal Galaxies at Intermediate
  Redshift

abstract:
  (abridged) We have investigated 136 Chandra extragalactic sources without
broad optical emission lines, including 93 galaxies with narrow emission lines
(NELG) and 43 with only absorption lines (ALG). Based on fx/fo, Lx, X-ray
spectral hardness and optical emission line diagnostics, we have conservatively
classified 36 normal galaxies (20 spirals and 16 ellipticals) and 71 AGNs. We
found no statistically significant evolution in Lx/LB, within the limited z
range. We have built log(N)-log(S), after correcting for completeness based on
a series of simulations. The best-fit slope is -1.5 for both S and B energy
bands, which is considerably steeper than that of the AGN-dominated cosmic
background sources, but slightly flatter than the previous estimate, indicating
normal galaxies will not exceed the AGN population until fx ~ 2 x 10-18 erg s-1
cm-2 (a factor of ~5 lower than the previous estimate). A group of NELGs appear
to be heavily obscured in X-rays, i.e., a typical type 2 AGN. After correcting
for intrinsic absorption, their X-ray luminosities could be Lx > 10^44 erg s-1,
making them type 2 quasar candidates. While most X-ray luminous ALGs (XBONG -
X-ray bright, optically normal galaxy candidates) do not appear to be
significantly absorbed, we found two heavily obscured objects, which could be
as luminous as an unobscured broad-line quasar. Among 43 ALGs, we found two E+A
galaxy candidates with strong Balmer absorption lines, but no [OII] line. The
X-ray spectra of both galaxies are soft and one of them has a nearby close
companion galaxy, supporting the merger/interaction scenario rather than the
dusty starburst hypothesis.


title: Low State, Phase-Resolved IR Spectroscopy of VV Puppis

abstract:
  We present phase-resolved low resolution $JHK$ and higher resolution $K$-band
spectroscopy of the polar VV Pup. All observations were obtained when VV Pup
was in a low accretion state having a K magnitude near 15. The low resolution
observations reveal cyclotron emission in the $J$ band during some phases,
consistent with an origin near the active 30.5 MG pole on the white dwarf. The
secondary in VV Pup appears to be a normal M7V star and we find that the $H$
and $K$ band fluxes are entirely due to this star at all orbital phases during
the low accretion state. We use our higher resolution Keck spectroscopy to
produce the first $K$-band radial velocity curve for VV Pup. Our orbital
solution yields $K_2$=414$\pm27$ km sec$^{-1}$ and leads to mass estimates of
M$_1$=0.73$\pm$0.05 M$_{\odot}$ and M$_2$=0.10$\pm$0.02 M$_{\odot}$. We find
that the mass accretion rates during the normal low states of the polars VV
Pup, EF Eri, and EQ Cet are near 10$^{-13}$ M$_{\odot}$ yr$^{-1}$. The fact
that \.M is not zero in low state polars indicates active secondary stars in
these binary systems, including the sub-stellar donor star present in EF Eri.


title:
Spectroscopy of GRB 051111 at z=1.54948: Kinematics and Elemental
  Abundances of the GRB Environment and Host Galaxy

abstract:
  We present a high-resolution, high signal-to-noise optical spectrum of the
afterglow of GRB 051111 obtained with the HIRES spectrograph on the Keck I 10-m
telescope. The spectrum exhibits three redshifted absorption systems with the
highest, at z=1.54948, arising in the GRB host galaxy. While the Ly-alpha
feature is outside the range of our spectrum, the high column density of
weakly-depleted Zn suggests that the host is a damped Lyman-alpha system with
N(HI)>10^21(Z/Z_sun)^-1. The bulk of the gas (>80%) is confined to a narrow
velocity range of |v|<30 km/s exhibiting strong dust depletion of refractory
elements such as Fe and Cr. The depletion pattern is similar to that observed
in warm disk clouds of the Milky Way. We also detect absorption from all
ground-level fine-structure states of FeII, the first such example in a QSO-DLA
or GRB-absorption spectrum, which indicate conditions that are consistent with
the "warm disk" depletion pattern. The absorption profiles of FeII and MgII
extend over several hundred km/s, with a depletion pattern that more closely
resembles that of QSO-DLAs, suggesting that the sight line to GRB 051111 probes
the halo of the host galaxy in addition to the dense disk. Thus, detailed
diagnostics of the interstellar medium of GRB host galaxies continue to provide
insight into regions which are generally missed in quasar surveys.


title: Green Bank Telescope Studies of Giant Pulses from Millisecond Pulsars

abstract:
  We have conducted a search for giant pulses from four millisecond pulsars
using the 100m Green Bank Telescope. Coherently dedispersed time-series from
PSR J0218+4232 were found to contain giant pulses of very short intrinsic
duration whose energies follow power-law statistics. The giant pulses are in
phase with the two minima of the radio integrated pulse profile but are phase
aligned with the peaks of the X-ray profile. Historically, individual pulses
more than 10-20 times the mean pulse energy have been deemed to be ``giant
pulses''. As only 4 of the 155 pulses had energies greater than 10 times the
mean pulse-energy, we argue the emission mechanism responsible for giant pulses
should instead be defined through: (a) intrinsic timescales of microsecond or
nanosecond duration; (b) power-law energy statistics; and (c) emission
occurring in narrow phase-windows coincident with the phase windows of
non-thermal X-ray emission. Four short-duration pulses with giant-pulse
characteristics were also observed from PSR B1957+20. As the inferred magnetic
fields at the light cylinders of the millisecond pulsars that emit giant pulses
are all very high, this parameter has previously been considered to be an
indicator of giant pulse emissivity. However, the frequency of giant pulse
emission from PSR~B1957+20 is significantly lower than for other millisecond
pulsars that have similar magnetic fields at their light cylinders. This
suggests that the inferred magnetic field at the light cylinder is a poor
indicator of the rate of emission of giant pulses.


title: The electromagnetic model of Gamma Ray Bursts

abstract:
  I describe electromagnetic model of gamma ray bursts and contrast its main
properties and predictions with hydrodynamic fireball model and its
magnetohydrodynamical extension. The electromagnetic model assumes that
rotational energy of a relativistic, stellar-mass central source
(black-hole--accretion disk system or fast rotating neutron star) is converted
into magnetic energy through unipolar dynamo mechanism, propagated to large
distances in a form of relativistic, subsonic, Poynting flux-dominated wind and
is dissipated directly into emitting particles through current-driven
instabilities. Thus, there is no conversion back and forth between internal and
bulk energies as in the case of fireball model. Collimating effects of magnetic
hoop stresses lead to strongly non-spherical expansion and formation of jets.
Long and short GRBs may develop in a qualitatively similar way, except that in
case of long bursts ejecta expansion has a relatively short, non-relativistic,
strongly dissipative stage inside the star. Electromagnetic and fireball models
(as well as strongly and weakly magnetized fireballs) lead to different early
afterglow dynamics, before deceleration time. Finally, I discuss the models in
view of latest observational data in the Swift era.


title: The Chandra XBootes Survey - III: Optical and Near-IR Counterparts

abstract:
  The XBootes Survey is a 5-ks Chandra survey of the Bootes Field of the NOAO
Deep Wide-Field Survey (NDWFS). This survey is unique in that it is the largest
(9.3 deg^2), contiguous region imaged in X-ray with complementary deep optical
and near-IR observations. We present a catalog of the optical counterparts to
the 3,213 X-ray point sources detected in the XBootes survey. Using a Bayesian
identification scheme, we successfully identified optical counterparts for 98%
of the X-ray point sources. The optical colors suggest that the optically
detected galaxies are a combination of z<1 massive early-type galaxies and
bluer star-forming galaxies whose optical AGN emission is faint or obscured,
whereas the majority of the optically detected point sources are likely quasars
over a large redshift range. Our large area, X-ray bright, optically deep
survey enables us to select a large sub-sample of sources (773) with high X-ray
to optical flux ratios (f_x/f_o>10). These objects are likely high redshift
and/or dust obscured AGN. These sources have generally harder X-ray spectra
than sources with 0.1<f_x/f_o<10. Of the 73 X-ray sources with no optical
counterpart in the NDWFS catalog, 47 are truly optically blank down to R~25.5
(the average 50% completeness limit of the NDWFS R-band catalogs). These
sources are also likely to be high redshift and/or dust obscured AGN.


title:
Hypervelocity intracluster stars ejected by supermassive black hole
  binaries

abstract:
  Hypervelocity stars have been recently discovered in the outskirts of
galaxies, such as the unbound star in the Milky Way halo, or the three
anomalously fast intracluster planetary nebulae (ICPNe) in the Virgo Cluster.
These may have been ejected by close 3-body interactions with a binary
supermassive black hole (SMBBH), where a star which passes within the semimajor
axis of the SMBBH can receive enough energy to eject it from the system. Stars
ejected by SMBBHs may form a significant sub-population with very different
kinematics and mean metallicity than the bulk of the intracluster stars. The
number, kinematics, and orientation of the ejected stars may constrain the mass
ratio, semimajor axis, and even the orbital plane of the SMBBH. We investigate
the evolution of the ejected debris from a SMBBH within a clumpy and
time-dependent cluster potential using a high resolution, self-consistent
cosmological N-body simulation of a galaxy cluster. We show that the predicted
number and kinematic signature of the fast Virgo ICPNe is consistent with
3-body scattering by a SMBBH with a mass ratio $10:1$ at the center of M87.


title:
On the transition from Galactic to extragalactic cosmic-rays: spectral
  and composition features from two opposite scenarios

abstract:
  We study the phenomenology of cosmic-rays (CRs) at the galactic/extragalactic
transition, focusing on two opposite models for the composition of the
extragalactic (EG) component. Model A assumes a mixed source composition, with
nuclear abundances similar to that of the low-energy CRs, while model B assumes
that the EG sources accelerate only protons. We study the limits within which
both scenarios can reproduce the high-energy CR data, from the point of view of
the energy spectrum, each with its own interpretation of the ankle (as the
GCR/EGCR transition for model A; as a pair-production dip for model B) and its
own source spectrum (in E?2.3 model A; in E?2.6 or E?2.7 for model B). We then
focus on the energy evolution of the high-energy CR composition and compare our
predictions for two main composition-related observables (Xmax and hlnAi) with
the available data, to conclude that model A is currently favoured.
Uncertainties are discussed and distinctive features of the two models are
identified, which should allow one to distinguish between the models in the
near future when more precise measurements are available with higher-statistics
experiments.


title: Stellar Populations in Bulges

abstract:
  We present line strengths in the bulges and inner disks of 38 galaxies in the
local universe, including several galaxies whose bulges were previously
identified as being disk-like in their colors or kinematics, to see if their
spectral properties reveal evidence for secular evolution. We find that red
bulges of all Hubble types are similar to luminous ellipticals in their central
stellar populations. They have large luminosity-weighted ages, metallicities,
and alpha/Fe ratios. Blue bulges can be separated into a metal-poor class that
is restricted to late-types with small velocity dispersion and a young,
metal-rich class that includes all Hubble types and velocity dispersions.
Luminosity-weighted metallicities and alpha/Fe ratios are sensitive to central
velocity dispersion and maximum disk rotational velocity. Red bulges and
ellipticals follow the same scaling relations. We see differences in some
scaling relations between blue and red bulges and between bulges of barred and
unbarred galaxies. Most bulges have decreasing metallicity with increasing
radius; galaxies with larger central metallicities have steeper gradients.
Where positive age gradients (with the central regions being younger) are
present, they are invariably in barred galaxies. The metallicities of bulges
are correlated with those of their disks. While this and the differences
between barred and unbarred galaxies suggest that secular evolution cannot be
ignored, our results are generally consistent with the hypothesis that mergers
have been the dominant mechanism responsible for bulge formation.


title:
A Near-Infrared Analysis of the Submillimeter Background and the Cosmic
  Star-Formation History

abstract:
  We use new deep near-infrared (NIR) and mid-infrared (MIR) observations to
analyze the 850$~\mu$m image of the GOODS HDF-N region. We show that much of
the submillimeter background at this wavelength is picked out by sources with
$H(AB)$ or 3.6um (AB)<23.25 (1.8 uJy). These sources contribute an 850um
background of 24\pm2 Jy deg^-2. This is a much higher fraction of the measured
background (31-45 Jy deg^-2) than is found with current 20cm or 24um samples.
Roughly one-half of these NIR-selected sources have spectroscopic
identifications, and we can assign robust photometric redshifts to nearly all
of the remaining sources using their UV to MIR spectral energy distributions.
We use the redshift and spectral type information to show that a large fraction
of the 850um background light comes from sources with z=0-1.5 and that the
sources responsible have intermediate spectral types. Neither the elliptical
galaxies, which have no star formation, nor the bluest galaxies, which have
little dust, contribute a significant amount of 850um light, despite the fact
that together they comprise approximately half of the galaxies in the sample.
The galaxies with intermediate spectral types have a mean flux of 0.40\pm0.03
mJy at 850um and 9.1\pm0.3 uJy at 20cm.
  The redshift distribution of the NIR-selected 850um light lies well below
that of the much smaller amount of light traced by the more luminous, radio-
selected submillimeter sources. We therefore require a revised star-formation
history with a lower star-formation rate at high redshifts. We use a stacking
analysis of the 20cm light in the NIR sample to show that the star-formation
history of the total 850um sample is relatively flat down to z~1 and that half
of the total star formation occurs at redshifts z<1.4.


title:
Elemental Abundance Ratios in Stars of the Outer Galactic Disk. III.
  Cepheids

abstract:
  We present metallicities, [Fe/H], and elemental abundance ratios, [X/Fe], for
a sample of 24 Cepheids in the outer Galactic disk. The sample have
Galactocentric distances covering 12 < R_GC (kpc) < 17.2 making them the most
distant Galactic Cepheids upon which detailed abundance analyses have been
performed. We find sub-solar ratios of [Fe/H] and overabundances of [alpha/Fe],
[La/Fe], and [Eu/Fe]. All abundance ratios exhibit a dispersion that exceeds
the measurement uncertainties. As seen in our previous studies of old open
clusters and field giants, enhanced ratios of [alpha/Fe] and [Eu/Fe] reveal
that recent star formation has taken place in the outer disk.
  The outer disk Cepheids appear to exhibit a bimodal distribution for [Fe/H]
and [alpha/Fe]. Most of the Cepheids continue the trends with Galactocentric
distance exhibited by Andrievsky's larger Cepheid sample and we refer to these
stars as the "Galactic Cepheids". A minority of the Cepheids show considerably
lower [Fe/H] and higher [alpha/Fe] and we refer to these stars as the "Merger
Cepheids". One signature of a merger event would be composition differences
between the "Galactic" and "Merger" Cepheids. The Cepheids satisfy this
requirement and we speculate that the distinct compositions suggest that the
"Merger Cepheids" may have formed under the influence of significant merger or
accretion events. The short lifetimes of the Cepheids reveal that the merger
event may be on-going with the Monoceros ring and Canis Major galaxy being
possible merger candidates. [Abridged]


title:
Determination of the Cosmic Distance Scale from Sunyaev-Zel'dovich
  Effect and Chandra X-ray Measurements of High Redshift Galaxy Clusters

abstract:
  We determine the distance to 38 clusters of galaxies in the redshift range
0.14 < z < 0.89 using X-ray data from Chandra and Sunyaev-Zeldovich Effect data
from the Owens Valley Radio Observatory and the Berkeley-Illinois-Maryland
Association interferometric arrays. The cluster plasma and dark matter
distributions are analyzed using a hydrostatic equilibrium model that accounts
for radial variations in density, temperature and abundance, and the
statistical and systematic errors of this method are quantified. The analysis
is performed via a Markov chain Monte Carlo technique that provides
simultaneous estimation of all model parameters. We measure a Hubble constant
of 76.9 +3.9-3.4 +10.0-8.0 km/s/Mpc (statistical followed by systematic
uncertainty at 68% confidence) for an Omega_M=0.3, Omega_Lambda=0.7 cosmology.
We also analyze the data using an isothermal beta model that does not invoke
the hydrostatic equilibrium assumption, and find H_0=73.7 +4.6-3.8 +9.5-7.6
km/s/Mpc; to avoid effects from cool cores in clusters, we repeated this
analysis excluding the central 100 kpc from the X-ray data, and find H_0=77.6
+4.8-4.3 +10.1-8.2 km/s/Mpc. The consistency between the models illustrates the
relative insensitivity of SZE/X-ray determinations of H_0 to the details of the
cluster model. Our determination of the Hubble parameter in the distant
universe agrees with the recent measurement from the Hubble Space Telescope key
project that probes the nearby universe.


title: Supermassive Black Holes at the Center of Galaxies

abstract:
  This was my final paper for the AST 308 Galaxies class at Michigan State
University. Using many sources I was able to compile a moderate amount of
information concerning the evidence for, and the formation of Supermassive
Black Holes.


title: Multi-Generational Star Formation in L1551

abstract:
  The L1551 molecular cloud contains two small clusters of Class 0 and I
protostars, as well as a halo of more evolved Class II and III YSOs, indicating
a current and at least one past burst of star formation. We present here new,
sensitive maps of 850 and 450 um dust emission covering most of the L1551
cloud, new CO J=2-1 data of the molecular cloud, and a new, deep, optical image
of [SII] emission. No new Class 0/I YSOs were detected. Compact sub-millimetre
emitters are concentrated in two sub-clusters: IRS5 and L1551NE, and the
HL~Tauri group. Both stellar groups show significant extended emission and
outflow/jet activity. A jet, terminating at HH 265 and with a very weak
associated molecular outflow, may originate from LkHa 358, or from a binary
companion to another member of the HL Tauri group. Several Herbig Haro objects
associated with IRS5/NE were clearly detected in the sub-mm, as were faint
ridges of emission tracing outflow cavity walls. We confirm a large-scale
molecular outflow originating from NE parallel to that from IRS5, and suggest
that the "hollow shell" morphology is more likely due to two interacting
outflows. We confirm the presence of a prestellar core (L1551-MC) of mass 2-3
Mo north-west of IRS5. The next generation cluster may be forming in this core.
The L1551 cloud appears cometary in morphology, and appears to be illuminated
and eroded from the direction of Orion, perhaps explaining the multiple
episodes of star formation in this cloud. The full paper (including figures)
can be downloaded at http://www.jach.hawaii.edu/~gms/l1551/l1551-apj641.pdf, or
viewed at http://www.jach.hawaii.edu/~gms/l1551/.


title: Upper limits on the hot Jupiter fraction in the field of NGC 7789

abstract:
  We describe a method of estimating the abundance of short-period extrasolar
planets based on the results of a photometric survey for planetary transits. We
apply the method to a 21-night survey with the 2.5m Isaac Newton Telescope of
\~32000 stars in a ~0.5 deg by 0.5 deg square field including the open cluster
NGC 7789. From the colour-magnitude diagram we estimate the mass and radius of
each star by comparison with the cluster main sequence. We search for injected
synthetic transits throughout the lightcurve of each star in order to determine
their recovery rate, and thus calculate the expected number of transit
detections and false alarms in the survey. We take proper account of the
photometric accuracy, time sampling of the observations and criteria
(signal-to-noise and number of transits) adopted for transit detection.
Assuming that none of the transit candidates found in the survey will be
confirmed as real planets, we place conservative upper limits on the abundance
of planets as a function of planet radius, orbital period and spectral type.


title: Convection and observable properties of late-type giants

abstract:
  We show that contrary to what is expected from 1D stationary model
atmospheres, 3D hydrodynamical modeling predicts a considerable influence of
convection on the spectral properties of late-type giants. This is due to the
fact that convection overshoots into the formally stable outer atmospheric
layers producing a notable granulation pattern in the 3D hydrodynamical models,
which has a direct influence on the observable spectra and colors. Within the
framework of standard 1D model atmospheres the average thermal stratification
of the 3D hydro model can not be reproduced with any reasonable choice of the
mixing length parameter and formulation of the turbulent pressure. The
differences in individual photometric colors -- in terms of 3D versus 1D --
reach up to ~0.2 mag, or \Delta Teff~70K. We discuss the impact of full 3D
hydrodynamical models on the interpretation of observable properties of
late-type giants, briefly mentioning problems and challenges which need to be
solved for bringing these models to a routine use within the astronomical
community in 5-10 years from now.


title: Photometric colors of late-type giants: theory versus observations

abstract:
  To assess the current status in the theoretical modeling of the spectral
properties of late-type giants, we provide a comparison of synthetic
photometric colors of late-type giants (calculated with PHOENIX, MARCS and
ATLAS model atmospheres) with observations, at [M/H]=0.0 and -2.0. Overall,
there is a good agreement between observed and synthetic colors, and synthetic
colors and published Teff-color relations, both at [M/H]=0.0 and -2.0.
Deviations from the observed trends in Teff-color planes are generally within
\pm 150K (or less) in the effective temperature range Teff=3500-4800K.
Synthetic colors calculated with different stellar atmosphere models typically
agree to ~100K, within a large range of effective temperatures and gravities.
Some discrepancies are seen in the Teff-(B-V) plane below Teff~3800K at
[M/H]=0.0, due to difficulties in reproducing the 'turn-off' to the bluer
colors which is seen in the observed data at Teff~3600K. Note that at
[M/H]=-2.0 effective temperatures given by the scale of Alonso et al. (1999)
are generally lower than those resulting from other Teff-color relations based
both on observed and synthetic colors.


title: Exponential Cardassian Universe

abstract:
  The expectation of explaining cosmological observations without requiring new
energy sources is forsooth worthy of investigation. In this letter, a new kind
of Cardassian models, called exponential Cardassian models, for the late-time
universe are investigated in the context of the spatially flat FRW universe
scenario. We fit the exponential Cardassian models to current type Ia
supernovae data and find they are consistent with the observations.
Furthermore, we point out that the equation-of-state parameter for the
effective dark fluid component in exponential Cardassian models can naturally
cross the cosmological constant divide $w=-1$ that observations favor mildly
without introducing exotic material that destroy the weak energy condition.


title: The host galaxies of low luminosity quasars at high redshift

abstract:
  We present VLT/ISAAC near-infrared imaging of the host galaxies of 15 low
luminosity quasars at 1 < z < 2. This work complements our studies to trace the
cosmological evolution of the host galaxies of high luminosity quasars. The
radio-loud (RLQ) and radio-quiet (RQQ) quasars have similar distribution of
redshift and luminosity, and together the high and low luminosity quasars cover
a large range of the quasar luminosity function. Both RLQ and RQQ hosts
resemble massive inactive ellipticals undergoing passive evolution. However,
RLQ hosts are systematically more luminous than RQQ hosts, as also found for
the high luminosity quasars. The difference in the host luminosity remains the
same from z = 2 to z = 0. For the entire set of quasars, we find a correlation
between the nuclear and the host luminosities, albeit with a large scatter. The
correlation is less apparent for the RQQs than for the RLQs.


title:
An investigation of the submillimeter background radiation using SCUBA
  and Spitzer

abstract:
  We investigate the redshift dependence of the contribution to the
extragalactic far-infrared/sub-millimeter background from galaxies detected by
the Spitzer Space Telescope at 8um and 24um. Using seven-band optical to
mid-infrared photometry, we estimate photometric redshifts for the Spitzer
sources which appear to be mostly L* galaxies at a median redshift of z=1.0.
These sources, extracted from deep 8um and 24um mosaics of the CUDSS 14-hour
field with 5sigma limits of 5.8uJy and 70uJy respectively, exhibit significant
850um and 450um emission as observed by SCUBA. At 850um, after removing
>=4sigma sources and those securely identified in our previous cross-matching
paper, we measure stacked flux at the significance level of 4.4sigma and
2.9sigma from the full 8um and 24um galaxy catalogue respectively. At 450um,
flux is detected from all 8um galaxies at the level of 3.5sigma, while there is
no significant emission from the 24um galaxies. We find that the 850um flux is
emitted almost exclusively at z>~1.3 from the Spitzer sources with 0.44mJy
(4.7sigma) per 8um source and 0.51mJy (2.8sigma) per 24um source. This
corresponds to a contribution of (16+/-3)% toward the 850um extra-galactic
background from the 8um sources and (5.0+/-1.8)% from the 24um sources. At
450um, only the 8um sources within the redshift interval 1<z<2 exhibit
significant emission with an average flux per source of 3.35mJy (3.0sigma).
This is a contribution of (37+/-12)% to the 450um background.


title: GRB 050911: a black hole - neutron star merger or a naked GRB

abstract:
  GRB 050911, discovered by the Swift Burst Alert Telescope, was not seen 4.6
hr later by the Swift X-ray Telescope, making it one of the very few X-ray
non-detections of a Gamma-Ray Burst (GRB) afterglow at early times. The
gamma-ray light-curve shows at least three peaks, the first two of which (~T_0
- 0.8 and T_0 + 0.2 s, where T_0 is the trigger time) were short, each lasting
0.5 s. This was followed by later emission 10-20 s post-burst. The upper limit
on the unabsorbed X-ray flux was 1.7 x 10^-14 erg cm^-2 s^-1 (integrating 46 ks
of data taken between 11 and 18 September), indicating that the decay must have
been rapid. All but one of the long bursts detected by Swift were above this
limit at ~4.6 hr, whereas the afterglows of short bursts became undetectable
more rapidly. Deep observations with Gemini also revealed no optical afterglow
12 hr after the burst, down to r=24.0 (5-sigma limit). We speculate that GRB
050911 may have been formed through a compact object (black hole-neutron star)
merger, with the later outbursts due to a longer disc lifetime linked to a
large mass ratio between the merging objects. Alternatively, the burst may have
occured in a low density environment, leading to a weak, or non-existent,
forward shock - the so-called 'naked GRB' model.


title: Micro-arcsecond light bending by Jupiter

abstract:
  The detectors designed for Gaia, the next ESA space astrometry mission to be
launched in 2011, will allow to observe repeatedly stars very close to
Jupiter's limb. This will open a unique opportunity to test General Relativity
by performing many Eddington-like experiments through the comparison between
the pattern of a starfield observed with or without Jupiter. We have derived
the main formulas relevant for the monopole and quadrupole light deflection by
an oblate planet and developed a simulator to investigate the processing of the
Gaia astrometric observation in the vicinity of the planet. The results show
that such an experiment carried out with the Gaia data will provide a new fully
independent determination of the PPN parameter gamma by means of differential
astrometric measurements and, more importantly, for the first time will
evidence the bending effect due to the quadrupole moment with a 3-sigma
confidence level. Given the accuracy of the experiment for the monopole
deflection, this will permit to test alternative modelling of the light bending
by moving masses.


title:
The Transition between Star Clusters and Dwarf Galaxies -- On the
  existence of a mass-radius relation for star clusters of masses >10^7 Mo: are
  these objects formed in mergers of stellar systems?

abstract:
  At which masses does the regime of globular clusters end and the one of dwarf
galaxies begin? And what separates these two classes of hot stellar systems?
  We examine to what extend very massive (>10^7 Mo) young star clusters are
similar to their lower mass counter parts and to which degree they resemble
other objects in their mass regime (dwarf--globular transition objects (DGTOs),
ultra compact dwarf galaxies (UCDs), galaxy nuclei).
  The comparison is performed by placing the recently observed very massive
young clusters onto known scaling relation defined by globular clusters (with
typical masses <10^6 Mo) and/or by hot stellar systems with sizes up to those
of giant galaxies.
  The very massive (>10^{6.5-7} Mo) young clusters seem to show a mass--radius
relation compatible with the one defined by hot stellar systems of galaxy mass.
This, in turn, can explain their location on the other scaling relations
investigated. It contrasts with the behaviour of the less massive young
clusters and of globular clusters, which do not exhibit any mass-radius
relation. However, the behaviour of the most massive clusters is similar to
that of most other objects in that mass regime (10^6-10^8 Mo).
  We show that the properties of young massive clusters are compatible with
other objects in the same mass regime such as DGTOs/UCDs. They present a
possible direct avenue of formation for those objects, which does not require
the transformation of a previously existing stellar system. Simulations and
observations support the possibility of the formation of such very massive
young clusters by early mergers of lower mass stellar clusters, which could
explain the emergence of a mass--radius relation.


title: Boundary layer emission in luminous LMXBs

abstract:
  We show that aperiodic and quasiperiodic variability of bright LMXBs - atoll
and Z- sources, on ~sec - msec time scales is caused primarily by variations of
the boundary layer luminosity. The accretion disk emission is less variable on
these time scales and its power density follows 1/f law, contributing to
observed flux variation at low frequencies and low energies only. The kHz QPOs
have the same origin as variability at lower frequencies - independent of the
nature of the "clock", the actual luminosity modulation takes place on the NS
surface. The boundary layer spectrum remains nearly constant during luminosity
variations and can be represented by the Fourier frequency resolved spectrum.
In the range of Mdot~(0.1-1)*Mdot_Edd it depends weakly on the global mass
accretion rate and in the limit Mdot~Mdot_Edd is close to Wien spectrum with
kT~2.4 keV. Its independence on the Mdot lends support to the suggestion by
Inogamov & Sunyaev (1999) that the boundary layer is radiation pressure
supported.
  Based on the knowledge of the boundary layer spectrum we attempt to relate
the motion along the Z-track to changes of physically meaningful parameters.
Our results suggest that the contribution of the boundary layer to the observed
emission decreases along the Z-track from conventional ~50% on the horizontal
branch to a rather small number on the normal branch. This decrease can be
caused, for example, by obscuration of the boundary layer by the geometrically
thickened accretion disk at Mdot~Mdot_Edd. Alternatively, this can indicate
significant change of the structure of the accretion flow at Mdot~Mdot_Edd and
disappearance of the boundary layer as a distinct region of the significant
energy release associated with the NS surface.


title:
L-band (3.5 micron) IR-excess in massive star formation, II. RCW 57/NGC
  3576

abstract:
  We present a JHKL survey of the massive star forming region RCW 57 (NGC 3576)
based on L-band data at 3.5 micron taken with SPIREX (South Pole Infrared
Explorer), and 2MASS JHK data at 1.25-2.2 micron. This is the second of two
papers, the first one concerning a similar JHKL survey of 30 Doradus.
Colour-colour and colour-magnitude diagrams are used to detect sources with
infrared excess. This excess emission is interpreted as coming from
circumstellar disks, and hence gives the cluster disk fraction (CDF). Based on
the CDF and the age of RCW 57, it is possible to draw conclusions on the
formation and early evolution of massive stars. The infrared excess is detected
by comparing the locations of sources in JHKL colour-colour and L vs. (K-L)
colour-magnitude diagrams to the reddening band due to interstellar extinction.
A total of 251 sources were detected. More than 50% of the 209 sources included
in the diagrams have an infrared excess. Comparison with other JHKL surveys,
including the results on 30 Doradus from the first paper, support a very high
initial disk fraction (>80%) even for massive stars, although there is an
indication of a possible faster evolution of circumstellar disks around high
mass stars. 33 sources only found in the L-band indicate the presence of
heavily embedded, massive Class I protostars. We also report the detection of
diffuse PAHs emission throughout the RCW 57 region.


title:
Improved HCN/HNC linelist, model atmospheres and synthetic spectra for
  WZ Cas

abstract:
  We build an accurate database of 5200 HCN and HNC rotation-vibration energy
levels, determined from existing laboratory data. 20~000 energy levels in the
Harris et al. (2002) linelist are assigned approximate quantum numbers. These
assignments, lab determined energy levels and Harris et al (2002) energy levels
are incorporated in to a new energy level list. A new linelist is presented, in
which frequencies are computed using the lab determined energy levels where
available, and the ab initio energy levels otherwise.
  The new linelist is then used to compute new model atmospheres and synthetic
spectra for the carbon star WZ Cas. This results in better fit to the spectrum
of WZ Cas in which the absorption feature at 3.56 micron is reproduced to a
higher degree of accuracy than has previously been possible. We improve the
reproduction of HCN absorption features by reducing the abundance of Si to
[Si/H] = --0.5 dex, however, the strengths of the $\Delta v=2$ CS band heads
are over-predicted.


title: The Epoch of Reionization

abstract:
  We have modelled the process of reionization of the IGM by photoionization by
galaxies, in order to predict the epoch of reionization. We use a sophisticated
semi-analytic model to track the formation of galaxies. Our study represents a
much more complete and physically consistent modelling of reionization than has
been conducted in the past, containing significant improvements in the
modelling of the collapse of baryons into dark matter halos, and in the model
for the cooling and condensation of gas within halos (including photoheating
from a self-consistently computed ionizing background and cooling due to H2).
We find that reionization can be achieved by z~10-20 in a LCDM cosmological
model with sigma8~0.9. However, a cosmological model with a running spectral
index is only able to achieve reionization before z~9 if extreme assumptions
are made about the physics of feedback at high redshifts. We also consider the
galaxy formation model discussed by Baugh et al., and find that it is able to
reionize the Universe by z~12. The previous results assume that all of the
ionizing photons produced by stars in galaxies are able to escape and ionize
the IGM. If this is not the case, then the redshift of reionization could be
substantially reduced. We find that extended periods of partial reionization
and double reionizations can occur in models in which the first stars formed
via cooling by H2 molecules, are very massive, and in which the escape fraction
of ionizing photons ~10-30%. Such models do not fully reionize until z~6-7, but
predict an electron scattering optical depth as large as 0.15. Models with
lower sigma8=0.7-0.8 as suggested by the recent WMAP three year data have
reduced redshifts of reionization, but can be consistent with the lower optical
depth also suggested by the WMAP three year data.


title:
Ram pressure stripping of disc galaxies: The role of the inclination
  angle

abstract:
  We present 3D hydrodynamical simulations of ram pressure stripping of massive
disc galaxies in clusters. Studies of galaxies that move face-on have predicted
that in such a geometry the galaxy can lose a substantial amount of its
interstellar medium. But only a small fraction of galaxies is moving face-on.
Therefore, in this work we focus on a systematic study of the effect of the
inclination angle between the direction of motion and the galaxy's rotation
axis.
  In agreement with some previous works, we find that the inclination angle
does not play a major role for the mass loss as long as the galaxy is not
moving close to edge-on. We can predict this behaviour by extending Gunn &
Gott's estimate of the stripping radius, which is valid for face-on geometries,
to moderate inclinations.
  The inclination plays a role as long as the ram pressure is comparable to
pressures in the galactic plane, which can span two orders of magnitude. For
very strong ram pressures, the disc will be stripped completely, and for very
weak ram pressures, mass loss is negligible independent of inclination. We show
that in non-edge-on geometries the stripping proceeds remarkably similar. A
major difference between different inclinations is the degree of asymmetry
introduced in the remaining gas disc.
  We demonstrate that the tail of gas stripped from the galaxy does not
necessarily point in a direction opposite to the galaxy's direction of motion.
Therefore, the observation of a galaxy's gas tail may be misleading about the
galaxy's direction of motion.


title:
Dwarf elliptical galaxies in Centaurus A group: stellar populations in
  AM 1339-445 and AM 1343-452

abstract:
  We study the red giant populations of two dE galaxies, AM 1339-445 and AM
1343-452, with the aim of investigating the number and luminosity of any upper
asymptotic giant branch (AGB) stars present. The galaxies are members of the
Centaurus A group (D~3.8 Mpc) and are classified as outlying (R~350 kpc)
satellites of Cen A. The analysis is based on near-IR photometry for individual
red giant stars, derived from images obtained with ISAAC on the VLT. The
photometry, along with optical data derived from WFPC2 images retrieved from
the HST science archive, enable us to investigate the stellar populations of
the dEs in the vicinity of the red giant branch (RGB) tip. In both systems we
find stars above the RGB tip, which we interpret as intermediate-age upper-AGB
stars. The presence of such stars is indicative of extended star formation in
these dEs similar to that seen in many, but not all, dEs in the Local Group.
For AM 1339-445, the brightest of the upper-AGB stars have Mbol~-4.5 while
those in AM 1343-452 have Mbol~-4.8 mag. These luminosities suggest ages of
approximately 6.5+/-1 and 4+/-1 Gyr as estimates for the epoch of the last
episode of significant star formation in these systems. In both cases the
number of upper-AGB stars suggests that ~15% of the total stellar population is
in the form of intermediate-age stars, considerably less than is the case for
outlying dE satellites of the Milky Way such as Fornax and LeoI.


title:
Cosmology of Mass-Varying Neutrinos Driven by Quintessence: Theory and
  Observations

abstract:
  The effects of mass-varying neutrinos on cosmic microwave background (CMB)
anisotropies and large scale structures (LSS) are studied. In these models,
dark energy and neutrinos are coupled such that the neutrino masses are
functions of the scalar field playing the role of dark energy. We begin by
describing the cosmological background evolution of such a system. It is
pointed out that, similar to models with a dark matter/dark energy interaction,
the apparent equation of state measured with SNIa can be smaller than -1. We
then discuss the effect of mass-varying neutrinos on the CMB anisotropies and
the matter power spectrum. A suppression of power in the CMB power spectrum at
large angular scales is usually observed. We give an explanation for this
behaviour and discuss different couplings and quintessence potentials to show
the generality of the results obtained. We perform a likelihood analysis using
wide-ranging SNIa, CMB and LSS observations to assess whether such theories are
viable. Treating the neutrino mass as a free parameter we find that the
constraints on the coupling are weak, since CMB and LSS surveys give only upper
bounds on the neutrino mass. However, fixing a priori the neutrino masses, we
find that there is some evidence that the existence of such a coupling is
actually preferred by current cosmological data over the standard LambdaCDM
cosmology.


title:
Very Large Primordial Non-Gaussianity from multi-field: Application to
  Massless Preheating

abstract:
  In this paper we derive a generic expression, which is valid for scales
larger than Hubble radius and contains only the local terms, for the second
order curvature perturbations for more than one field, provided the expansion
is sourced by the energy density of a single field. As an application,
motivated by our previous paper [1], we apply our formalism to two fields
during preheating, where the inflaton oscillations are sourced by
$\lambda\phi^4$ potential which is governing the expansion of the Universe. A
second field $\sigma$, coupled to the inflaton through $g^2\phi^2\sigma^2$, is
excited from the vacuum fluctuations. The excited modes of $\sigma$ amplify the
super-Hubble isocurvature perturbations, which seed the second order curvature
perturbations to give rise to a significantly large non-Gaussianity. Our
results show that within 3 inflaton oscillations for a range of parameters, $1<
g^2/\lambda < 3$, the non-Gaussianity parameter becomes: $f_{NL}\geq {\cal
O}(1000)$, which is already ruled out by the current WMAP observation.


title:
Do measurements of the one-point distribution of aperture-mass improve
  constraints on cosmology ?

abstract:
  We study the possibility of using the entire probability distribution
function (PDF) of the aperture mass Map and its related cumulative probability
distribution function (CPDF) to obtain meaningful constraints on cosmological
parameters. Deriving completely analytic expressions for the associated
covariance matrices, we construct the Fisher matrix and use it to estimate the
accuracy with which various cosmological parameters can be recovered from
future surveys using such statistics. This formalism also includes the effect
of various noises such as intrinsic ellipticity distribution of galaxies and
finite survey size. The estimation errors are then compared with the ones
derived from low order moments of the PDF (variance and skewness) to check how
efficiently the high Map tail can be used to constrain cosmological parameters
such as Omega_m, sigma_8 and dark energy equation of state w_de. We find that
for future surveys such as JDEM the full PDF does not bring significant
tightening of constraints on cosmology beyond what is already achievable by the
joint use of second and third order moments.


title:
Nonlinear Decline-Rate Dependence and Intrinsic Variation of Type Ia
  Supernova Luminosities

abstract:
  Published B and V fluxes from nearby Type Ia supernovae are fitted to
light-curve templates with 4-6 adjustable parameters. Separately, B magnitudes
from the same sample are fitted to a linear dependence on B-V color within a
post-maximum time window prescribed by the CMAGIC method. These fits yield two
independent SN magnitude estimates B_max and B_BV. Their difference varies
systematically with decline rate Delta m_15 in a form that is compatible with a
bilinear but not a linear dependence; a nonlinear form likely describes the
decline-rate dependence of B_max itself. A Hubble fit to the average of B_max
and B_BV requires a systematic correction for observed B-V color that can be
described by a linear coefficient R = 2.59 +- 0.24, well below the coefficient
R_B ~ 4.1 commonly used to characterize the effects of Milky Way dust. At 99.9%
confidence the data reject a simple model in which no color correction is
required for SNe that are clustered at the blue end of their observed color
distribution. After systematic corrections are performed, B_max and B_BV
exhibit mutual rms intrinsic variation equal to 0.074 +- 0.019 mag, of which at
least an equal share likely belongs to B_BV. SN magnitudes measured using
maximum-luminosity or CMAGIC methods show comparable rms deviations of order ~
0.14 mag from the Hubble line. The same fit also establishes a 95% confidence
upper limit of 486 km/s on the rms peculiar velocity of nearby SNe relative to
the Hubble flow.


title:
Polycyclic Aromatic Hydrocarbons Orbiting HD 233517, an Evolved
  Oxygen-Rich Red Giant

abstract:
  We report spectra obtained with the Spitzer Space Telescope in the 5 to 35
micron range of HD 233517, an evolved K2 III giant with circumstellar dust. At
wavelengths longer than 13 microns, the flux is a smooth continuum that varies
approximately as frequency to the -5/3 power. For wavelengths shorter than 13
microns, although the star is oxygen-rich, PAH features produced by carbon-rich
species at 6.3 microns, 8.2 microns, 11.3 microns and 12.7 microns are detected
along with likely broad silicate emission near 20 microns. These results can be
explained if there is a passive, flared disk orbiting HD 233517. Our data
support the hypothesis that organic molecules in orbiting disks may be
synthesized in situ as well as being incorporated from the interstellar medium.


title: AG Carinae: a Luminous Blue Variable with a high rotational velocity

abstract:
  We report the detection of broad absorptions due to Si IV 4088-4116 A in the
Luminous Blue Variable (LBV) AG Carinae during its last hot phase (2001-2003).
Our NLTE spectral analysis, with the radiative transfer code CMFGEN, revealed
the photospheric nature of these lines predicting, however, much narrower and
deeper absorption profiles than observed. Using a recently-developed code to
compute synthetic spectra in 2D geometry allowing for the effects of rotation,
we could match the broad absorptions with a high projected rotational velocity
of 190 +/- 30 km/s on 2001 April. Analysis of spectra obtained on 2002 March
and 2003 January, when the star was cooling, yielded to a projected rotational
velocity of 110 +/- 10 km/s and 85 +/- 10 km/s, respectively. The derived
rotational velocities are proportional to R^-1, as expected from angular
momentum conservation. We discuss the effects of such high rotation on the
spectral analysis of AG Car, and on the wind terminal velocity. Our results
show direct spectroscopic evidence, for the first time, that a LBV may rotate
at a significant fraction of its break-up velocity. Thus, AG Car (and possibly
other LBVs) is indeed close to the Gamma-Omega limit, as predicted by
theoretical studies of LBVs.


title:
Turbulent Origin of the Galactic-Center Magnetic Field: Nonthermal Radio
  Filaments

abstract:
  A great deal of study has been carried out over the last twenty years on the
origin of the magnetic activity in the Galactic center. One of the most popular
hypotheses assumes milli-Gauss magnetic field with poloidal geometry, pervading
the inner few hundred parsecs of the Galactic-center region. However, there is
a growing observational evidence for the large-scale distribution of a much
weaker field of B \lesssim 10 micro G in this region. Here, we propose that the
Galactic-center magnetic field originates from turbulent activity that is known
to be extreme in the central hundred parsecs. In this picture the spatial
distribution of the magnetic field energy is highly intermittent, and the
regions of strong field have filamentary structures. We propose that the
observed nonthermal radio filaments appear in (or, possibly, may be identified
with) such strongly magnetized regions. At the same time, the large-scale
diffuse magnetic field is weak. Both results of our model can explain the
magnetic field measurements of the the Galactic-center region. In addition, we
discuss the role of ionized outflow from stellar clusters in producing the long
magnetized filaments perpendicular to the Galactic plane.


title: Cosmology with High-redshift Galaxy Survey: Neutrino Mass and Inflation

abstract:
  (abridged) High-z galaxy redshift surveys open up exciting possibilities for
precision determinations of neutrino masses and inflationary models. The high-z
surveys are more useful for cosmology than low-z ones owing to much weaker
non-linearities in matter clustering, redshift-space distortion and galaxy
bias. We can then utilize the two-dimensional information of the linear power
spectrum in angular and redshift space to measure the scale-dependent
suppression of matter clustering due to neutrino free-streaming as well as the
shape of the primordial power spectrum. To illustrate capabilities of high-z
surveys for constraining neutrino masses and the primordial power spectrum, we
compare three future redshift surveys covering 300 square degrees at 0.5<z<2,
2<z<4, and 3.5<z<6.5. We find that, combined with the cosmic microwave
background data expected from the Planck satellite, these surveys allow
precision determination of the total neutrino mass with the projected errors of
sigma(m_nu)=0.059, 0.043, and 0.025 eV, respectively, thus yielding a positive
detection of the neutrino mass rather than an upper limit, as sigma(m_nu) is
smaller than the lower limits to the neutrino masses implied from the neutrino
oscillation experiments. The accuracies of constraining the tilt and running
index of the primordial power spectrum, sigma(n_s)=(3.8, 3.7, 3.0)x10^-3, and
sigma(alpha_s)=(5.9, 5.7, 2.4)x10^-3, respectively, are smaller than the
current uncertainties by more than an order of magnitude, which will allow us
to discriminate between candidate inflationary models. In particular, the error
on alpha_s from the highest redshift survey is not very far away from the
prediction of a class of simple inflationary models driven by a massive scalar
field with self-coupling, alpha_s=-(0.8-1.2)x10^-3.


title:
Evolution in the black hole mass-bulge mass relation: a theoretical
  perspective

abstract:
  We explore the growth of super-massive black holes and host galaxy bulges in
the galaxy population using the Millennium Run LCDM simulation coupled with a
model of galaxy formation. We find that, if galaxy mergers are the primary
drivers for both bulge and black hole growth, then in the simplest picture one
should expect the mBH-mbulge relation to evolve with redshift, with a larger
black hole mass associated with a given bulge mass at earlier times relative to
the present day. This result is independent of an evolving cold gas fraction in
the galaxy population. The evolution arises from the disruption of galactic
disks during mergers that make a larger fractional mass contribution to bulges
at low redshift than at earlier epochs. There is no comparable growth mode for
the black hole population. Thus, this effect produces evolution in the
mBH-mbulge relation that is driven by bulge mass growth and not by black holes.


title:
Constraining the Projected Radial Distribution of Galactic Satellites
  with the Sloan Digital Sky Survey

abstract:
  We use the Sloan Digital Sky Survey (SDSS) spectroscopic sample to constrain
the projected radial distribution of satellites around isolated ~ L* galaxies.
We employ mock galaxy catalogs derived from high-resolution cosmological
simulations to investigate the effects of interloper contamination and show
that interlopers significantly bias the estimated slope of the projected radial
distribution of satellites. We also show that the distribution of interlopers
around galaxies is expected to be non-uniform in velocity space because
galaxies are clustered and reside in crowded environments. Successful methods
of interloper contamination correction should therefore take into account
environments of the host galaxies. Two such new methods are presented and the
most reliable of them is used to correct for interloper contamination in
analyses of the SDSS galaxy sample. The best fit power-law slope of the
interloper-corrected surface density distribution of satellites, Sigma(R) ~
R^alpha, in the volume-limited SDSS sample is alpha ~ -1.7 +/- 0.1, independent
of the galaxy and satellite luminosities. Comparison with Lambda-CDM
simulations shows that the radial distribution of the SDSS satellites is more
concentrated than that of subhalos around galaxy-sized halos, especially at R <
100 kpc/h. The predicted dark matter radial distribution is somewhat more
concentrated than the profile of the SDSS satellites, but the difference is not
statistically significant for our sample.


title: The Intrinsic Shape of Spiral Galaxies in the 2MASS Large Galaxy Atlas

abstract:
  The apparent shapes of spiral galaxies in the 2-Micron All Sky Survey Large
Galaxy Atlas are used to constrain the intrinsic shape of their disks. When the
distribution of apparent axis ratios is estimated using a nonparametric kernel
method, the shape distribution is inconsistent with axisymmetry at the 90%
confidence level in the B band and at the 99% confidence level in the K band.
If spirals are subdivided by Hubble type, the late-type spirals (Sc and later)
are consistent with axisymmetry, while the earlier spirals are strongly
inconsistent with axisymmetry. The distribution of disk ellipticity can be
fitted adequately with either a Gaussian or a lognormal distribution. The best
fits for the late spirals imply a median ellipticity of epsilon = 0.07 in the B
band and epsilon = 0.02 in the K band. For the earlier spirals, the best fits
imply a median ellipticity of epsilon = 0.18 in the B band and epsilon = 0.30
in the K band. The observed scatter in the Tully-Fisher relation, for both late
and early spirals, is consistent with the disk ellipticity measured in the B
band. This indicates that excluding spirals of Hubble type earlier than Sc will
reduce the intrinsic scatter in the Tully-Fisher relation used as a distance
indicator.


title:
Cosmology with wide-field SZ cluster surveys: Selection and Systematic
  Effects

abstract:
  The cosmological potential of large-scale structure observations for
cosmology have been extensively discussed in the litterature. In particular, it
has recently been shown how Sunyaev-Zel'dovich (SZ) cluster surveys can be used
to constrain dark energy parameters. In this paper, we study whether selection
and systematics effects will limit future wide-field SZ surveys from achieving
their cosmological potential. For this purpose, we use a sky simulation and an
SZ-cluster detection software presented in Pires et al. (2005), using the
future Olimpo, APEX and Planck surveys as a concrete examples. We show that the
SZ-cluster selection function and contamination of SZ-cluster catalogues are
more complex than is usually assumed. In particular, the simulated
field-to-field detected cluster counts is a factor 3 larger than the expected
Poisson fluctuations. We also study the impact of missing redshift information
and of the uncertainty of the scaling relations for low mass clusters. We
quantify, through hypothesis tests, how near-future SZ experiments can be used
to discriminate between different structure formation models. Using a maximum
likelihood approach, we then study the impact of these systematics on the joint
measurement of cosmological models and of cluster scaling relations.


title:
Discovery of the X-ray Counterpart to the Rotating Radio Transient
  J1819--1458

abstract:
  We present the discovery of the first X-ray counterpart to a Rotating RAdio
Transient (RRAT) source. RRAT J1819--1458 is a relatively highly magnetized (B
$\sim 5\times10^{13}$ G) member of a new class of unusual pulsar-like objects
discovered by their bursting activity at radio wavelengths. The position of
RRAT J1819--1458 was serendipitously observed by the {\sl Chandra} ACIS-I
camera in 2005 May. At that position we have discovered a pointlike source,
CXOU J181934.1--145804, with a soft spectrum well fit by an absorbed blackbody
with $N_H = 7^{+7}_{-4} \times 10^{21}$ cm$^{-2}$ and temperature $kT=0.12 \pm
0.04$ keV, having an unabsorbed flux of $\sim2 \times 10^{-12}$ ergs cm$^{-2}$
s$^{-1}$ between 0.5 and 8 keV. No optical or infrared (IR) counterparts are
visible within $1''$ of our X-ray position. The positional coincidence,
spectral properties, and lack of an optical/IR counterpart make it highly
likely that CXOU J181934.1--145804 is a neutron star and is the same object as
RRAT J1819--1458. The source showed no variability on any timescale from the
pulse period of 4.26~s up to the five-day window covered by the observations,
although our limits (especially for pulsations) are not particularly
constraining. The X-ray properties of CXOU J181934.1--145804, while not yet
measured to high precision, are similar to those of comparably-aged radio
pulsars and are consistent with thermal emission from a cooling neutron star.