title: Radio continuum imaging of FIR luminous QSOs at z>6

abstract:
  We present sensitive imaging at 1.4 GHz of the two highest redshift
far-infrared (FIR) luminous QSOs SDSS J114816.65+525150.2 (z=6.42) and SDSS
J104845.05+463718.3 (z=6.2). Radio continuum emission is detected from
J1148+5251 with S_{1.4} = 55 \pm 12 uJy, while J1048+4637 is marginally
detected with S_{1.4} = 26 \pm 12 uJy. Comparison of the radio and FIR
luminosities shows that both sources follow the radio-FIR correlation for star
forming galaxies, with implied (massive) star formation rates \sim 10^3 M_sun
year^{-1}, although we cannot rule-out as much as 50% of the FIR luminosity
being powered by the AGN. Five bright (> 22 mJy) radio sources are detected
within 8' of J1148+5251. This is a factor 30 more than expected for a random
field. Two sources have SDSS redshifts, including a z = 1.633 radio loud quasar
and a z = 0.05 radio galaxy. However, we do not find evidence for a galaxy
cluster in the SDSS data, at least out to z = 0.2. Considering the faint SDSS
magnitudes of the remaining radio sources, we conclude that the over-density of
radio sources could either be a statistical fluke, or a very large scale
structure (> 8 Mpc comoving) at z > 1. We also consider the possibility of
gravitational lensing by the closest (in angle) bright galaxy in the SDSS data
at z = 0.05, and conclude that the galaxy provides negligible magnification.


title: The Structure and Evolution of Early Cosmological HII Regions

abstract:
  We study the formation and evolution of HII regions around the first stars
formed at z=10-30. We use a one-dimensional Lagrangian hydrodynamics code which
self-consistently incorporates radiative transfer and non-equilibrium
primordial gas chemistry. The star-forming region is defined as a spherical gas
cloud with a Population III star embedded at the center. We explore a large
parameter space of host halo mass, gas density profile, and stellar luminosity.
The formation of the HII region is characterized by initial slow expansion of a
weak D-type ionization front near the center, followed by rapid propagation of
an R-type front throughout the outer gas envelope. We find that the transition
between the two front types is indeed a critical condition for the complete
ionization of halos of cosmological interest. In small mass (< 10^6 M_sun)
halos, the transition takes place within a few 10^5 yr, yielding high escape
fractions (>80%) of both ionizing and photodissociating photons. In larger mass
(> 10^7 M_sun) halos, the ionization front remains to be of D-type over the
lifetime of the massive star, the HII region is confined well inside the virial
radius, and the escape fractions are essentially zero. We derive an analytic
formula that reproduces well the results of our simulations. We discuss
immediate implications of the present results for the star formation history
and early reionization of the Universe.


title: Nucleosynthesis in multi-dimensional SNIa explosions

abstract:
  We present the results of nucleosynthesis calculations based on
multidimensional (2D and 3D) hydrodynamical simulations of the thermonuclear
burning phase in SNIa. The detailed nucleosynthetic yields of our explosion
models are calculated by post-processing the ejecta, using passively advected
tracer particles. The nuclear reaction network employed in computing the
explosive nucleosynthesis contains 383 nuclear species. We analyzed two
different choices of ignition conditions (centrally ignited, in which the
spherical initial flame geometry is perturbated with toroidal rings, and
bubbles, in which multi-point ignition conditions are simulated). We show that
unburned C and O varies typically from ~40% to ~50% of the total ejected
material.The main differences between all our models and standard 1D
computations are, besides the higher mass fraction of unburned C and O, the C/O
ratio (in our case is typically a factor of 2.5 higher than in 1D
computations), and somewhat lower abundances of certain intermediate mass
nuclei such as S, Cl, Ar, K, and Ca, and of 56Ni. Because explosive C and O
burning may produce the iron-group elements and their isotopes in rather
different proportions one can get different 56Ni-fractions (and thus supernova
luminosities) without changing the kinetic energy of the explosion. Finally, we
show that we need the high resolution multi-point ignition (bubbles) model to
burn most of the material in the center (demonstrating that high resolution
coupled with a large number of ignition spots is crucial to get rid of unburned
material in a pure deflagration SNIa model).


title:
Detecting compact dark matter in galaxy clusters via gravitational
  microlensing: A2218 & A370

abstract:
  After decades of searching, the true nature of dark matter still eludes us.
One potential probe of the form of dark matter in galaxy clusters is to search
for microlensing variability in the giant arcs and arclets. In this paper, a
simple method is introduced to characterize pixel variability in the limit of
high optical depth to microlensing. Expanding on earlier work, the expected
microlensing signal for two massive clusters, A2218 & A370 is calculated. It is
found that the microlensing signal depends sensitively upon the mix of smooth
and compact dark matter in the cluster. Comparison of two deep exposures taken
with James Webb Space Telescope or two hour long exposures taken with a
30-metre class telescope in two epochs separated by a few years will possibly
detect about a few dozen pixels which show strong variability due to
microlensing at five sigma level, revealing wealth of information on the
microlensing population.


title:
R-mode oscillations of rapidly rotating barotropic stars in general
  relativity: Analysis by the relativistic Cowling approximation

abstract:
  We develop a numerical scheme for obtaining the $r$-mode oscillations of
rapidly rotating relativistic stars. In the present scheme, we neglect all
metric perturbations and only take account of the dynamics of the fluid in the
background spacetime of the unperturbed star (the relativistic Cowling
approximation). We also assume the star is barotropic, i.e. neutrally stable
against convection under the assumption of adiabatic oscillations. Our
numerical scheme is based on the Yoshida-Eriguchi formulation for the analysis
of the general relativistic f-mode oscillations in the Cowling approximation
and a general relativistic generalization of the
Karino-Yoshida-Yoshida-Eriguchi's numerical scheme for obtaining oscillations
of rapidly rotating Newtonian stars. By this new numerical scheme, frequencies
of the $r$-mode oscillations are obtained as functions of the ratio of the
rotational energy to the absolute value of the gravitational energy $T/|W|$
along sequences of polytropic equilibrium stars whose ratio of the pressure to
the total energy density at the center of the star and the polytropic index are
kept constant. It is found that the dimensionless oscillation frequency
$\sigma/\Omega$ is a linearly decreasing function of $T/|W|$, where $\sigma$
and $\Omega$ are the oscillation frequency and the angular velocity of the star
measured in an inertial frame at spatial infinity. We also find that
oscillation frequencies of the $r$-modes are highly dependent on the
relativistic factor $M/R$ of the star as already found in previous studies in
which the slow rotation approximation has been used. Here $M$ and $R$ denote
the mass and radius of the star, respectively.


title:
The nature of close companions of the BL Lac Objects 1ES 0502+675 and
  1ES 1440+122

abstract:
  We report on deep radio images and optical spectroscopy of two BL Lac objects
that have very close compact companions. The two targets, 1ES 0502+675 and 1ES
1440+122, were selected from the HST imaging survey of 110 BL Lacs as
candidates for possible gravitational lensing. The new observations clearly
demonstrate that the companion objects are not secondary images of the active
nuclei but, in spite of the relatively low chance projection probability,
foreground Galactic stars. Gravitational lensing appears to be unimportant to
the BL Lac phenomenon. We discuss the radio properties of the BL Lac objects in
the context of standard beaming models, and show they are as expected for
beamed FRI radio galaxies.


title: Direct Non-baryonic Dark Matter Search - An experimental Review

abstract:
  This review will present the latest advances in the search for non-baryonic
dark matter from an experimental point of view, focusing more particularly on
the direct detection approach. After a brief reminder of the main motivations
for this search, we will expose the physical basis of WIMP detection, its
advantages and limitations. The current techniques having achieved the most
competitive results in terms of sensitivity will then be discussed. We will
conclude with a rapid overview of the future of direct detection experiments,
the techniques considered and their sensitivity goals.


title:
X-ray luminous galaxies II. Chandra and XMM-Newton Observations of the
  'composite' galaxy IRAS20051-1117

abstract:
  We present Chandra and XMM-Newton observations of the composite
star-forming/Seyfert galaxy IRAS20051-1117. The X-ray imaging and spectral
properties reveal the presence of an active nucleus. The Chandra image shows a
strong nuclear point source (L(2-10 keV) ~ 4x10^{42} erg s-1). The nuclear
X-ray source coincides with a bright, alsoun-resolved, UV source which appears
in the xmm Optical Monitor images. The xmm and chandra spectrum is well
represented by a power-law with a photon index of ~1.7-1.9 and a thermal
component with a temperature of 0.2 keV. We also detect an Fe line at 6.4 keV
with an equivalent width of ~0.3 keV, typical of the iron lines that have been
detected in the X-ray spectra of "classical" AGN. We find no evidence for
short-term variability in the X-ray light curves, while we detect no variations
between the xmm and chandra observations which are separated by about 20 days.
Optical spectroscopic observations which were performed ~2.5 months after the
xmm observation show that the optical spectrum is dominated by a star-forming
galaxy component, although a weak broad Halpha component is present, in
agreement with the results from past observations. The lack of strong AGN
signatures in the optical spectrum of the source can be explained by the
dilution of the nuclear AGN emission by the nuclear star-forming component and
the strong emission of the underlying, bright host galaxy.


title: Particle decay in inflationary cosmology

abstract:
  We investigate the relaxation and decay of a particle during inflation by
implementing the dynamical renormalization group. This investigation allows us
to give a meaningful definition for the decay rate in an expanding universe. As
a prelude to a more general scenario, the method is applied here to study the
decay of a particle in de Sitter inflation via a trilinear coupling to massless
conformally coupled particles, both for wavelengths much larger and much
smaller than the Hubble radius. For superhorizon modes we find that the decay
is of the form eta^{Gamma1} with eta being conformal time and we give an
explicit expression for Gamma1 to leading order in the coupling which has a
noteworthy interpretation in terms of the Hawking temperature of de Sitter
space-time. We show that if the mass M of the decaying field is << H then the
decay rate during inflation is enhanced over the Minkowski spacetime result by
a factor 2H/[pi M]. For wavelengths much smaller than the Hubble radius we find
that the decay law is e^{-alpha/[k H C(eta)} with C(eta) the scale factor and
alpha determined by the strength of the trilinear coupling. This result
suggests a suppression of power for long wavelength modes upon horizon
crossing. In all cases we find a substantial enhancement in the decay law as
compared to Minkowski space-time. These results suggest potential implications
for the spectrum of scalar density fluctuations as well as non-gaussianities.


title:
The polarization effects of radiation from magnetized envelopes and
  extended accretion structures

abstract:
  The results of numerical calculations of linear polarization from magnetized
spherical optically thick and optically thin envelopes are presented. We give
the methods how to distinguish magnetized optically thin envelopes from
optically thick ones using observed spectral distributions of the polarization
degree and the positional angle. The results of numerical calculations are used
for analysis of polarimetric observations of OB and WR stars, X-ray binaries
with black hole candidates (Cyg X-1, SS 433) and supernovae. The developed
method allows to estimate magnetic field strength for the objects mentioned
above.


title:
Detection of Bipolar Flow toward an Unusual SiO Maser Source IRAS
  19312+1950

abstract:
  We report a result of an interferometric observation toward an SiO maser
source, IRAS 19312+1950, in the HCO+ J=1-0 line with the
Berkeley-Illinois-Maryland-Association (BIMA) Millimeter Array. In the
spatially integrated spectrum of HCO+, two kinematic components were seen: a
strong line with a narrow width (~2 km/s, narrow component), and a weak
symmetric line with a broad width (~60 km/s, broad component). The line profile
of HCO+ are reminiscent of that of CO. In the integrated intensity map, we
found a pronounced bipolar shape consisting of lower-velocity parts of the
broad component. The higher-velocity part of the broad component originated in
a relatively small region (< 3"). The spatial structure of the narrow component
clearly correlated with near-infrared structure. The position-velocity diagrams
indicated presence of a bipolar outflow with an expansion velocity of about 10
km/s. On the basis of the present results, we suggest that the nature of the
bipolar flow seen in IRAS 19312+1950 is explained by hydrodynamical interaction
between an AGB wind and ambient material with axial symmetric structure.


title: Characterization and Status of a Terahertz Telescope

abstract:
  The Receiver Lab Telescope (RLT) is a ground-based terahertz observatory,
located at an altitude of 5525 m on Cerro Sairecabur, Chile. The RLT has been
in operation since late 2002, producing the first well-calibrated astronomical
data from the ground at frequencies above 1 THz. We discuss the status of this
telescope after 18 months of operation and plans for the upcoming observing
season.
  There are many practical challenges to operating a telescope at these
frequencies, including difficulties in determining the pointing, measuring the
telescope beam and efficiency, and calibrating data, resulting from high
receiver noise, receiver gain instabilities, and low atmospheric transmission.
We present some of the techniques we have employed for the RLT, including the
use of atmospheric absorption lines in the place of continuum measurements for
efficiency and beam measurements, and the utility of a Fourier-transform
spectrometer for producing reliable data calibration.


title:
Intracluster Stars and the Chemical Enrichment of the Intracluster
  Medium

abstract:
  We explore the contribution of intracluster stars (ICS) to the chemical
enrichment history of the intracluster medium (ICM). In contrast to scenarios
in which all the metals originate in cluster galaxies and are then transported
into the ICM, intracluster stars enrich the ICM in situ, thereby contributing
100% of their supernovae ejecta directly into the ICM. Modeling the ICS as an
ancient, single burst stellar population with a normal initial mass function,
we generate ICM iron abundances in the range of the observed values of several
tenths solar. Large observational and theoretical uncertainties preclude us
from concluding that the intracluster stars are the primary contributor of
metals to the ICM in general. However, for the two clusters in our sample, and
one from the literature, for which all of the required observational
constraints exist, we are able to reproduce between half and all of the ICM
iron. Due to the ubiquity of intracluster stars in clusters and their direct
connection with the ICM, we conclude that all models of the chemical enrichment
history and energy budget of the ICM should account for the impact of the ICS.


title: The Dynamics of Abell 2125

abstract:
  We present 371 galaxy velocities in the field of the very rich cluster Abell
2125 (z~0.25). These were determined using optical spectroscopy collected over
several years from both the WIYN 3.5m telescope and NOAO Mayall 4m telescope.
Prior studies at a variety of wavelengths (radio, optical, and X-ray) have
indicated that A2125 is a likely cluster-cluster merger, a scenario which we
are able to test using our large velocity database. We identified 224 cluster
galaxies, which were subjected to a broad range of statistical tests using both
positional and velocity information to evaluate the cluster dynamics and
substructure. The tests confirmed the presence of substructures within the
Abell 2125 system at high significance, demonstrating that A2125 is a complex
dynamical system. Comparison of the test results with existing simulations
strengthens the merger hypothesis, and provides clues about the merger geometry
and stage. The merger model for the system can reconcile A2125's low X-ray
temperature and luminosity with its apparently high richness, and might also
explain A2125's high fraction of active galaxies identified in prior radio and
optical studies.


title: Dust Reddening in SDSS Quasars

abstract:
  We explore the form of extragalactic reddening toward quasars using a sample
of 9566 quasars with redshifts 0<z<2.2, and accurate optical colors from the
Sloan Digital Sky Survey (SDSS). We confirm that dust reddening is the primary
explanation for the red ``tail'' of the color distribution of SDSS quasars. Our
fitting to 5-band photometry normalized by the modal quasar color as a function
of redshift shows that this ``tail'' is well described by SMC-like reddening
but not by LMC-like, Galactic, or Gaskell et al. (2004) reddening. Extension to
longer wavelengths using a subset of 1886 SDSS-2MASS matches confirms these
results at high significance. We carry out Monte-Carlo simulations that match
the observed distribution of quasar spectral energy distributions using a
Lorentzian dust reddening distribution; 2% of quasars selected by the main SDSS
targeting algorithm (i.e., which are not extincted out of the sample) have
E_{B-V} > 0.1; less than 1% have E_{B-V} > 0.2, where the extinction is
relative to quasars with modal colors. Reddening is uncorrelated with the
presence of intervening narrow-line absorption systems, but reddened quasars
are much more likely to show narrow absorption at the redshift of the quasar
than are unreddened quasars. Thus the reddening towards quasars is dominated by
SMC-like dust at the quasar redshift.


title: Multi-Wavelength Observations of Colliding Stellar Winds

abstract:
  Massive colliding wind binary stars serve as laboratories for the study of
strong-shock physics. In these systems fundamental flow parameters (velocities,
densities, directions) are often well known, and photon fields important for
Compton scattering and ionization are usually defined or constrained as well.
In this paper we review observed X-ray and radio characteristics of some
important colliding wind systems. We discuss how X-ray and radio observations
of these systems can be used to test models of the collision of massive flows
in the presence of intense UV radiation and magnetic fields.


title:
Supernova Remnants in the Magellanic Clouds. IV. X-Ray Emission from the
  Largest SNR in the LMC

abstract:
  We present the first X-ray detection of SNR 0450-70.9 the largest known
supernova remnant (SNR) in the Large Magellanic Cloud. To study the physical
conditions of this SNR, we have obtained XMM-Newton X-ray observations, optical
images and high-dispersion spectra, and radio continuum maps. Optical images of
SNR 0450-70.9 show a large, irregular elliptical shell with bright filaments
along the eastern and western rims and within the shell interior. The interior
filaments have higher [S II]/Halpha ratios and form an apparent inner shell
morphology. The X-ray emission region is smaller than the full extent of the
optical shell, with the brightest X-ray emission found within the small
interior shell and on the western rim of the large shell. The expansion
velocity of the small shell is ~220 km/s, while the large shell is ~120 km/s.
  The radio image shows central brightening and a fairly flat radio spectral
index over the SNR. However, no point X-ray or radio source corresponding to a
pulsar is detected and the X-ray emission is predominantly thermal. Therefore,
these phenomena can be most reasonably explained in terms of the advanced age
of the large SNR. Using hydrodynamic models combined with a nonequilibrium
ionization model for thermal X-ray emission, we derived a lower limit on the
SNR age of about 45,000 yr, well into the later stages of SNR evolution.
Despite this, the temperature and density derived from spectral fits to the
X-ray emission indicate that the remnant is still overpressured, and thus that
the development is largely driven by hot gas in the SNR interior.


title: ImpZ: a new photometric redshift code for galaxies and quasars

abstract:
  We present a combined galaxy-quasar approach to template-fitting photometric
redshift techniques and show the method to be a powerful one. The code (ImpZ)
is presented, developed and applied to two spectroscopic redshift catalogues,
namely the Isaac Newton Telescope Wide Angle Survey ELAIS N1 and N2 fields and
the Chandra Deep Field North. In particular, optical size information is used
to improve the redshift determination. The success of the code is shown to be
very good with Delta z/(1+z) constrained to within 0.1 for 92 per cent of the
galaxies in our sample. The extension of template-fitting to quasars is found
to be reasonable with Delta z/(1+z) constrained to within 0.25 for 68 per cent
of the quasars in our sample. Various template extensions into the far-UV are
also tested.


title: On the Origin of Dark Matter Cores in Dwarf Galaxies

abstract:
  In this paper, we study the dynamical stability and time evolution of the
central dark matter cores of low-mass (about 10^8-10^9 M_solar) galactic haloes
found in recent cold dark matter simulations at high redshift. From those
simulations we extract three haloes, assembled by hierarchical merging, that at
redshift z>10 display a core and we evolve them without further merging to low
redshift using direct N-body integration. The central core in the dark matter
profile is found to be dynamically stable: it survives for many crossing times
without evolution into a cusp. This result supports the claim that the mass
dependence of the central dark matter profiles of simulated haloes is a direct
consequence of the power spectrum of primordial density fluctuations. In
addition, we show that the simulated dark matter profiles, if they evolved in
isolation, are consistent with the observed velocity dispersion profile of
stars in the inner parts of the Draco dwarf spheroidal galaxy. Simple scaling
arguments are reviewed which explain the evolution of the concentration
parameter with redshift. We also review some arguments used to derive the
logarithmic slope of the inner and outer density profile.


title:
Spitzer Space Telescope Spectroscopy of Ices toward Low Mass Embedded
  Protostars

abstract:
  Sensitive 5-38 um Spitzer Space Telescope (SST) and ground based 3-5 um
spectra of the embedded low mass protostars B5 IRS1 and HH46 IRS show deep ice
absorption bands superposed on steeply rising mid-infrared continua. The ices
likely originate in the circumstellar envelopes. The CO2 bending mode at 15 um
is a particularly powerful tracer of the ice composition and processing
history. Toward these protostars, this band shows little evidence for thermal
processing at temperatures above 50 K. Signatures of lower temperature
processing are present in the CO and OCN- bands, however. The observed CO2
profile indicates an intimate mixture with H2O, but not necessarily with CH3OH,
in contrast to some high mass protostars. This is consistent with the low CH3OH
abundance derived from the ground based L band spectra. The CO2/H2O column
density ratios are high in both B5 IRS1 and HH46 IRS (~35%). Clearly, the SST
spectra are essential to study ice evolution in low mass protostellar
environments, and to eventually determine the relation between interstellar and
solar system ices.


title:
The Mass Function of the Stellar Component of Galaxies in the Sloan
  Digital Sky Survey

abstract:
  Using the MOPED algorithm we determine non-parametrically the Stellar Mass
Function of 96,545 galaxies from the Sloan Digital Sky Survey data release one.
By using the reconstructed spectrum due to starlight we can eliminate
contamination from either emission lines or AGN components. Our results give
excellent agreement with previous works, but extend their range by more than
two decades in mass to 10^{7.5} < M_s/h^{-2}M_\odot < 10^{12}. We present both
a standard Schechter fit and a fit modified to include an extra, high-mass
contribution, possibly from cluster cD galaxies. The Schechter fit parameters
are $\phi^*=(7.7\pm 0.8)\times 10^{-3} h^3 Mpc^{-3}$, $M^*=(7.53 \pm 0.04)
\times 10^{10} h^{-2}M_\odot$ and $\alpha=-1.167\pm 0.004$. Our sample also
yields an estimate for the contribution from baryons in stars to the critical
density of $\Omega_{b*}h=(2.40 \pm 0.04) \times 10^{-3}$, in good agreement
with other indicators. Error bars are statistical and a Salpeter IMF is assumed
throughout. We find no evolution of the mass function in the redshift range
$0.05 < z < 0.34$ indicating that almost all present day stars were already
formed at $z \sim 0.34$ with little or no star formation activity since then
and that the evolution seen in the luminosity function must be largely due to
stellar fading.


title: INTEGRAL observation of 3EG J1736-2908

abstract:
  The possible identification by INTEGRAL of the EGRET source 3EG J1736-2908
with the active galactic nucleus GRS 1734-292 is discussed. The latter was
discovered in 1990 and later identified with a Seyfert 1 galaxy. At the time of
the compilation of the 3rd EGRET Catalog, it was not considered as a possible
counterpart of the source 3EG J1736-2908, which remained unidentified. A
detailed multiwavelength study of the EGRET error circle is presented, by
including archival radio, soft- and hard-X observations, suggesting that GRS
1734-292 could be a likely counterpart of 3EG J1736-2908, even though this
poses very interesting questions about the production mechanisms of gamma-rays
with energies greater than 100 MeV.


title:
The Formation and Evolution of Planetary Systems: First Results from a
  Spitzer Legacy Science Program

abstract:
  We present 3-160 micron photometry obtained with the IRAC and MIPS
instruments for the first five targets from the Spitzer Legacy Science Program
"Formation and Evolution of Planetary Systems" and 4-35 micron
spectro-photometry obtained with the IRS for two sources. We discuss in detail
our observations of the debris disks surrounding HD 105 (G0V, 30 +- 10 Myr) and
HD 150706 (G3V, ~ 700 +- 300 Myr). For HD 105, possible interpretations include
large bodies clearing the dust inside of 45 AU or a reservoir of gas capable of
sculpting the dust distribution. The disk surrounding HD 150706 also exhibits
evidence of a large inner hole in its dust distribution. Of the four survey
targets without previously detected IR excess, spanning ages 30 Myr to 3 Gyr,
the new detection of excess in just one system of intermediate age suggests a
variety of initial conditions or divergent evolutionary paths for debris disk
systems orbiting solar-type stars.


title:
A Chandra View of the Normal SO Galaxy NGC 1332: II: Solar Abundances in
  the Hot Gas and Implications for SN Enrichment

abstract:
  We present spectral analysis of the diffuse emission in the normal, isolated,
moderate-Lx S0 NGC 1332, constraining both the temperature profile and the
metal abundances in the ISM. The characteristics of the point source population
and the gravitating matter are discussed in two companion papers. The diffuse
emission comprises hot gas, with an ~isothermal temperature profile (~0.5 keV),
and emission from unresolved point-sources. In contrast with the cool cores of
many groups and clusters, we find a small central temperature peak. We obtain
emission-weighted abundance contraints within 20 kpc for several key elements:
Fe, O, Ne, Mg and Si. The measured iron abundance (Z_Fe=1.1 in solar units;
>0.53 at 99% confidence) strongly excludes the very sub-solar values often
historically reported for early-type galaxies but agrees with recent
observations of brighter galaxies and groups. The abundance ratios, with
respect to Fe, of the other elements were also found to be ~solar, although
Z_o/Z_Fe was significantly lower (<0.4). Such a low O abundance is not
predicted by simple models of ISM enrichment by Type Ia and Type II supernovae,
and may indicate a significant contribution from primordial hypernovae.
Revisiting Chandra observations of the moderate-Lx, isolated elliptical NGC
720, we obtain similar abundance constraints. Adopting standard SNIa and SNII
metal yields, our abundance ratio constraints imply 73+/-5% and 85+/-6% of the
Fe enrichment in NGC 1332 and NGC 720, respectively, arises from SNIa. Although
these results are sensitive to the considerable systematic uncertainty in the
SNe yields, they are in good agreement with observations of more massive
systems. These two moderate-Lx early-type galaxies reveal a consistent pattern
of metal enrichment from cluster scales to moderate Lx/Lb galaxies. (abridged)


title: Core-Collapse Supernovae Induced by Anisotropic Neutrino Radiation

abstract:
  We demonstrate the important role of anisotropic neutrino radiation on the
mechanism of core-collapse supernova explosions. Through a new parameter study
with a fixed radiation field of neutrinos, we show that prolate explosions
caused by globally anisotropic neutrino radiation is the most effective
mechanism of increasing the explosion energy when the total neutrino luminosity
is given. This is suggestive of the fact that the expanding materials of SN
1987A has a prolate geometry.


title:
The Role of Gas in the Merging of Massive Black Holes in Galactic
  Nuclei. II. Black Hole Merging in a Clumpy Disk

abstract:
  Using SPH numerical simulations, we investigate the effects of gas on the
inspiral and merger of a massive black hole binary. This study is motivated by
the very massive nuclear gas disks observed in the central regions of merging
galaxies. Here we present results that expand on the treatment in a previous
work (Escala, Larson, Coppi & Mardones 2004; henceforth Paper I), by studying
more realistic models. We run a variety of models, ranging from simulations
with a relatively smooth gas disk to cases in which the gas has a more clumpy
spatial distribution. We also vary the inclination angle between the plane of
the binary and the plane of the disk, and the mass ratio between the MBHs and
the gaseous disk. We find that as in Paper I, in the early evolution of the
system the binary separation diminishes due to gravitational drag, and in the
later stages the medium responds by forming an ellipsoidal density enhancement
whose axis lags behind the binary axis; this offset produces a torque on the
binary that causes continuing loss of angular momentum and is able to reduce
the separation to distances where gravitational radiation is efficient. In the
simulations that we perform, we find that the coalescence timescale for the MBH
binary varies between 5 10^6 yr and 2.5 10^7 yr. For MBHs that satisfy the
observed `m-sigma_c' relation, we predict that in a merger of galaxies that
have at least 1% of their total mass in gas, the MBHs will coalesce soon after
the galaxies merge. We also predict that if the MBHs depart from the
`m-sigma_c' relation, the MBH binary can create a circumbinary gap in the disk
that stalls the coalescence, but this gap formation can act as a
self-regulatory mechanism on MBH growth that can help to explain the existence
of the `m-sigma_c' relation.


title:
Effects of Early Cosmic Reionization on the Substructure Problem in
  Galactic Halo

abstract:
  Recent observations on the cosmic microwave background by Wilkinson Microwave
Anisotropy Probe(WMAP) strongly suggest that the reionization of the universe
took place quite early (z \sim 17). On the other hand, it has been pointed out
that the cold dark matter cosmology suffers from the substructure problem that
subgalactic halos are overproduced than the observed dwarf galaxies in the
Local Group. In this paper, as a potential mechanism to solve this problem, we
consider the feedback effects of the early reionization on the formation of
small-scale structures. For this purpose, we perform 3D radiation hydrodynamic
simulations with incorporating the radiative transfer for ionizing photons. As
a result, it is found that the early reionization is so devastating for
low-mass systems with M_{vir}\la 10^8 M_\odot or v_{circ}\la 20km/s, and almost
all gas is photo-evaporated in more than 95% of low-mass systems. Such a strong
negative feedback on the formation of low-mass galaxies may solve the
substructure problem and support the picture that Local Group dwarf galaxies
are descendants of the more massive halos that experienced and survived tidal
stripping.


title:
Secular evolution versus hierarchical merging: galaxy evolution along
  the Hubble sequence, in the field and rich environments

abstract:
  In the current galaxy formation scenarios, two physical phenomena are invoked
to build disk galaxies: hierarchical mergers and more quiescent external gas
accretion, coming from intergalactic filaments. Although both are thought to
play a role, their relative importance is not known precisely. Here we consider
the constraints on these scenarios brought by the observation-deduced star
formation history on the one hand, and observed dynamics of galaxies on the
other hand: the high frequency of bars and spirals, the high frequency of
perturbations such as lopsidedness, warps, or polar rings.
  All these observations are not easily reproduced in simulations without
important gas accretion. N-body simulations taking into account the mass
exchange between stars and gas through star formation and feedback, can
reproduce the data, only if galaxies double their mass in about 10 Gyr through
gas accretion. Warped and polar ring systems are good tracers of this
accretion, which occurs from cold gas which has not been virialised in the
system's potential. The relative importance of these phenomena are compared
between the field and rich clusters. The respective role of mergers and gas
accretion vary considerably with environment.


title:
Detection of Lyman-alpha emission from a DLA galaxy: Possible
  implications for a luminosity-metallicity relation at z = 2-3

abstract:
  In an ongoing programme to identify a sample of high z DLA galaxies we have
found the long sought for case of a Ly-alpha emitter seen in the centre of a
broad DLA trough. This is the predicted `textbook case' of an intervening DLA
galaxy if DLA galaxies are small, but would not be expected if intervening high
redshift DLA galaxies have large gaseous disks. The Ly-alpha flux is
5.4{+2}{-0.8} * 1e-17 ergs/s/cm2 similar to what has been found in previously
known high z DLA galaxies. The impact parameter is found to be 0.3+-0.3 arcsec.
This is smaller than what was found in previous cases but still consistent with
random sight-lines through absorbers with mean impact parameter ~1 arcsec. Of
the 24 DLAs targeted in the NICMOS imaging survey five have now been identified
as Ly-alpha emitters. The DLA galaxies with detected Ly-alpha emission tend to
have higher interstellar metallicities than those with undetected Ly-alpha
emission. This is plausibly explained as a consequence of a positive
correlation between the Ly-alpha line luminosities of the galaxies and their
metallicities, although the present sample is too small for a definitive
conclusion. The available observations of high-redshift DLA galaxies are also
consistent with a negative correlation between Ly-alpha equivalent widths and
metallicities, as seen in nearby star-forming galaxies and usually attributed
to the preferential absorption of Ly-alpha photons by dust grains.


title: Protostars in the Elephant Trunk Nebula

abstract:
  The optically-dark globule IC 1396A is revealed using Spitzer images at 3.6,
4.5, 5.8, 8, and 24 microns to be infrared-bright and to contain a set of
previously unknown protostars. The mid-infrared colors of the 24 microns
detected sources indicate several very young (Class I or 0) protostars and a
dozen Class II stars. Three of the new sources (IC 1396A: gamma, delta, and
epsilon) emit over 90% of their bolometric luminosities at wavelengths greater
than 3 microns, and they are located within ~0.02 pc of the ionization front at
the edge of the globule. Many of the sources have spectra that are still rising
at 24 microns. The two previously-known young stars LkHa 349 a and c are both
detected, with component c harboring a massive disk and component a being bare.
Of order 5% of the mass of material in the globule is presently in the form of
protostars in the 10^5 to 10^6 yr age range. This high star formation rate was
likely triggered by radiation from a nearby O star.


title: VLT FORS-1 observations of NGC 6397: Evidence for mass segregation

abstract:
  We present (V,V-I) VLT-FORS1 observations of the Galactic Globular Cluster
NGC 6397. We derive accurate color--magnitude diagrams and luminosity functions
(LFs) of the cluster Main Sequence (MS) for two fields extending from a region
near the centre of the cluster out to ~ 10 arcmin. The photometry of these
fields produces a narrow MS extending down to V ~ 27, much deeper than any
previous ground based study on this system and comparable to previous HST
photometry. The V, V-I CMD also shows a deep white dwarf cooling sequence
locus, contaminated by many field stars and spurious objects. We concentrate
the present work on the analysis of the MSLFs derived for two annuli at
different radial distance from the center of the cluster. Evidence of a
clear-cut correlation between the slope of the observed LFs before reaching the
turn-over, and the radial position of the observed fields inside the cluster
area is found. We find that the LFs become flatter with decreasing radius (x ~
0.15 for 1'< R1 < 5.5'; x ~ 0.24 for 5.5'< R2 <9.8'; core radius, rc = 0.05'),
a trend that is consistent with the interpretation of NGC 6397 as a dynamically
relaxed system. This trend is also evident in the mass function.


title: High resolution Chandra X-ray imaging of the nucleus of M33

abstract:
  We show with a short Chandra HRC-S exposure that the powerful X-ray source
coincident with the nucleus of M33 is unresolved at the highest spatial
resolution available to date (0"4). The source flux is variable, doubling
during the 5 ks exposure. The combination of properties exhibited by M33 X-8
establishes the source as the nearest example of the ultra-luminous X-ray
sources that have been uncovered in other nearby galaxies. On short timescales,
we set limits of 9% r.m.s. variability for pulsations in the 0.01-1000 Hz
range.


title:
Nonradial and nonpolytropic astrophysical outflows VI. Overpressured
  winds and jets

abstract:
  By means of a nonlinear separation of the variables in the governing full set
of the magnetohydrodynamic (MHD) equations for axisymmetric plasmas we analyse
an exact model for magnetized and rotating outflows which are hotter and
overpressured at their axis. These outflows start subsonically and
subAlfv\'enically from the central gravitating source and its surrounding
accretion disk. Subsequently, they accelerate thermally and
magnetocentrifugally and thus cross the appropriate MHD critical points,
reaching high values of the Alfv\'en Mach number. Three types of solutions are
found : (a) collimated jet-type outflows from efficient magnetic rotators with
the flow confined by the magnetic hoop stress; (b) radially expanding wind-type
outflows analogous to the solar wind, from inefficient magnetic rotators or
strongly overpressured sources; (c) terminated solutions with increasing
amplitude of oscillations in the width of the beam. In contrast to previously
studied underpressured outflows, the transition from collimated jets to
uncollimated winds is not continuous in the appropriate parametric space with a
gap where no stationary solution is found. Superfast at infinity solutions are
filtered by three critical surfaces corresponding to the three known limiting
characteristics or separatrices of MHD wind theory. Collimated and terminated
solutions cross the slow, Alfv\'en and fast magneto-acoustic critical points.
Radially expanding solutions cross the slow and Alfv\'en critical points while
the last boundary condition is imposed by requiring that the pressure vanishes
at infinity.


title: The analysis of Abell 1835 using a deprojection technique

abstract:
  We present the results from a detailed deprojection analysis of Abell 1835 as
observed by {\it XMM-Newton}. If we fit the spectra with an isothermal plasma
model, the deprojected temperature profile is flat in the outer region around
7.6 keV and decreases to $\sim$ 5.6 keV in the center, which may be connected
with the gas cooling. In the central part, a two-component thermal plasma model
can fit the spectrum significantly better. Moreover, the cool component (T
$\sim$ 1.8 keV) has a much lower metal abundance than the hot component (T
$\sim$ 8 keV), which may be due to the longer cooling time for the cool gas
with lower abundance. In addition, it was found that without a main isothermal
component, the standard cooling flow model cannot fit the spectrum
satisfactorily. From the isothermal model fitting results we also derived the
electron density $n_e$, and fitted its radial distribution with a
double-$\beta$ model. The $n_e$ profile inferred with the double-$\beta$ model
and the deprojected X-ray gas temperature profile were then combined to derive
the total mass and the total projected mass of the cluster. The projected mass
is lower than that derived from the weak lensing method. However, assuming that
the cluster extends to a larger radius $\sim15'$ as found by Clowe & Schneider
(2002), the two results are consistent within the error bars. Furthermore, we
calculated the projected mass within the radius of $\sim$ 153 kpc implied by
the presence of a gravitational lensing arc, which is about half of the mass
determined from the optical lensing.


title: Formation and evolution of clumpy tidal tails around globular clusters

abstract:
  We present some results of numerical simulations of a globular cluster
orbiting in the central region of a triaxial galaxy on a set of 'loop' orbits.
Tails start forming after about a quarter of the globular cluster orbital
period and develop, in most cases, along the cluster orbit, showing clumpy
substructures as observed, for example, in Palomar 5. If completely detectable,
clumps can contain about 7,000 solar masses each, i.e. about 10% of the cluster
mass at that epoch. The morphology of tails and clumps and the kinematical
properties of stars in the tails are studied and compared with available
observational data. Our finding is that the stellar velocity dispersion tends
to level off at large radii, in agreement to that found for M15 and Omega
Centauri.


title:
New response functions for absorption-line indices from high-resolution
  spectra

abstract:
  Basing on the huge library of 1-A resolution spectra calculated by Munari et
al. over a large range of logT, log g, [Fe/H] and both for solar and a-enhanced
abundance ratios [a/Fe], we present theoretical absorption-line indices on the
Lick system. First we derive the so-called response functions (RFs) of Tripicco
& Bell for a wide range of logT, log g, [Fe/H] and [a/Fe]=+0.4 dex. The RFs are
commonly used to correct indices with solar [a/Fe] ratios to indices with
[a/Fe]>0. Not only the RFs vary with the type of star but also with the
metallicity. Secondly, with the aid of this and the fitting functions (FFs) of
Worthey et al., we derive the indices for single stellar populations and
compare them with those obtained by previous authors, e.g. Tantalo & Chiosi.
The new RFs not only supersede the old ones by Tripicco & Bell, but also show
that Hb increases with the degree of enhancement in agreement with the results
by Tantalo & Chiosi. The new indices for single stellar populations are used to
derive with aid of the recursive Minimum Distance method the age, metallicity
and degree of enhancement of a sample of Galactic Globular Clusters for which
these key parameters have been independently derived from the Colour-Magnitude
Diagram and/or spectroscopic studies. The agreement is remarkably good.


title: Rotating compact stars with exotic matter

abstract:
  We have constructed models of uniformly rotating compact stars including
hyperons, Bose-Einstein condensates of antikaons and quarks. First order phase
transitions from hadronic to antikaon condensed matter and then to quark matter
are considered here. For the equation of state undergoing phase transitions to
antikaon condensates, the third family of compact stars are found to exist in
the fixed angular velocity sequences. However, the third family solution
disappears when the compact stars rotate very fast. For this equation of state,
the fixed baryon number supramassive sequence shows a second stable part after
the unstable region but no back bending phenomenon. On the other hand, we
observe that the rotation gives rise to a second maximum beyond the neutron
star maximum for the equation of state involving phase transitions to both
antikaon condensed and quark matter. In this case, the back bending phenomenon
has been observed in the supramassive sequence as a consequence of the first
order phase transition from $K^-$ condensed to quark matter. And the back
bending segment contains stable configurations of neutron stars.


title: The Double-Lined Spectrum of LBV 1806-20

abstract:
  Despite much theoretical and observational progress, there is no known firm
upper limit to the masses of stars. Our understanding of the interplay between
the immense radiation pressure produced by massive stars in formation and the
opacity of infalling material is subject to theoretical uncertainties, and many
observational claims of ``the most massive star'' have failed the singularity
test. LBV 1806-20 is a particularly luminous object, L~10^6 Lsun, for which
some have claimed very high mass estimates (M_initial>200 Msun), based, in
part, on its similarity to the Pistol Star. We present high-resolution
near-infrared spectroscopy of LBV 1806-20, showing that it is possibly a binary
system with components separated in velocity by ~70 kms. If correct, then this
system is not the most massive star known, yet it is a massive binary system.
We argue that a binary, or merged, system is more consistent with the ages of
nearby stars in the LBV 1806-20 cluster. In addition, we find that the velocity
of V_LSR=36 kms is consistent with a distance of 11.8 kpc, a luminosity of
10^6.3 Lsun, and a system mass of ~130 Msun.


title: Star Formation in HI Selected Galaxies I: Sample Characteristics

abstract:
  A sample of 69 galaxies with radial velocities less than 2500 km/s was
selected from the HI Parkes All Sky Survey (HIPASS) and imaged in broad band B
and R and narrow band H-alpha to deduce details about star formation in nearby
disk galaxies while avoiding surface brightness selection effects. The sample
is dominated by late-type, dwarf disks (mostly Sc and Sm galaxies) with
exponential disk scale lengths of about 1 to 5 kpc. The HIPASS galaxies on
average have lower star formation rates (SFRs) and are bluer and lower surface
brightness than an optically selected sample. HII regions were detected in all
but one of the galaxies. Many galaxies had as few as two to five HII regions.
The galaxies' H-alpha equivalent widths, colors, and SFRs per unit HI mass are
best explained by young mean ages (about 3 to 5 Gyr according to Schmidt Law
models) with star formation histories where the SFRs were higher in the past.
Comparison of the surface brightness coverage of the HIPASS galaxies with that
of an optically selected sample shows that such a sample may miss about 10% of
the local galaxy number density and could possibly miss as much as 3 to 4% of
the SFR density. The amount lower surface brightness galaxies contribute to the
total luminosity density may be insignificant, but this conclusion is somewhat
dependent on how the fluxes of these objects are determined.


title: The Physics of E x B-Drifting Jets

abstract:
  It is argued that the physical jets consist of monoenergetic pairplasma
performing almost lossfree ExB-drift. The observed broad power-law spectra
result on collision with obstacles, via post-acceleration by the (huge)
convected Poynting flux.


title: Astrophysical Jets and Outflows

abstract:
  Highly collimated supersonic jets and less collimated outflows are observed
to emerge from a wide variety of astrophysical objects. They are seen in young
stellar objects (YSOs), proto-planetary nebulae, compact objects (like galactic
black holes or microquasars, and X-ray binary stars), and in the nuclei of
active galaxies (AGNs). Despite their different physical scales (in size,
velocity, and amount of energy transported), they have strong morphological
similarities. What physics do they share? These systems either hydrodynamic or
magnetohydrodynamic (MHD) in nature and are, as such, governed by non-linear
equations. While theoretical models helped us to understand the basic physics
of these objects, numerical simulations have been allowing us to go beyond the
one-dimensional, steady-state approach extracting vital information. In this
lecture, the formation, structure, and evolution of the jets are reviewed with
the help of observational information, MHD and purely hydrodynamical modeling,
and numerical simulations. Possible applications of the models particularly to
YSOs and AGN jets are addressed.


title: BBN For Pedestrians

abstract:
  The simplest, `standard' model of Big Bang Nucleosynthesis (SBBN) assumes
three light neutrinos (N_nu = 3) and no significant electron neutrino
asymmetry, leaving only one adjustable parameter: the baryon to photon ratio
eta. The primordial abundance of any one nuclide can, therefore, be used to
measure the baryon abundance and the value derived from the observationally
inferred primordial abundance of deuterium closely matches that from current,
non-BBN data, primarily from the WMAP survey. However, using this same estimate
there is a tension between the SBBN-predicted 4He and 7Li abundances and their
current, observationally inferred primordial abundances, suggesting that N_nu
may differ from the standard model value of three and/or that there may be a
non-zero neutral lepton asymmetry (or, that systematic errors in the abundance
determinations have been underestimated or overlooked). The differences are not
large and the allowed ranges of the BBN parameters permitted by the data are
quite small. Within these ranges, the BBN-predicted abundances of D, 3He, 4He,
and 7Li are very smooth, monotonic functions of eta, N_nu, and the lepton
asymmetry. It is possible to describe the dependencies of these abundances (or
powers of them) upon the three parameters by simple, linear fits which, over
their ranges of applicability, are accurate to a few percent or better. The
fits presented here have not been maximized for their accuracy but, for their
simplicity. To identify the ranges of applicability and relative accuracies,
they are compared to detailed BBN calculations; their utility is illustrated
with several examples. Given the tension within BBN, these fits should prove
useful in facilitating studies of the viability of proposals for non-standard
physics and cosmology, prior to undertaking detailed BBN calculations.


title:
Orbital Modulation of the Apparent Dispersion Measure Towards PSR
  J0737-3039A

abstract:
  The paper was withdrawn because the effect is due to the data reduction
methodology. See the text file for details.


title:
Chandra Observation of the Merging Cluster A168: A Late Stage in the
  Evolution of a Cold Front

abstract:
  We present Chandra observations of the cool cluster A168, for which previous
X-ray imaging and optical studies indicated a merger of two subclusters nearly
in the plane of the sky. We derive a temperature map for A168, which shows that
the merger has proceeded beyond the core passage and is near subcluster
turnaround. It also reveals an unusual feature -- the gas core of one of the
subclusters forms a tongue-like structure extending ahead (in the direction of
motion) of the subcluster center. The coolest cluster gas is found in a
crescent-shaped region at the tip of this tongue, and forms a cold front in
pressure equilibrium with the external gas. In contrast with this feature's
forward location, previously observed merger cold fronts (e.g., A3667,
1E0657--56) lagged behind their host subclusters, as expected in the presense
of ram pressure. We propose that A168 illustrates a much later stage in the
evolution of a cold front, when its host subcluster approaches the apocenter of
the merger orbit where the ram pressure on its gas drops sharply. As a result,
a large chunk of the subcluster gas ``slingshots'' past the dark matter center,
becomes unbound from the subcluster and expands adiabatically, as seen in some
recent hydrodynamic simulations.


title: Class Discovery in Galaxy Classification

abstract:
  In recent years, automated, supervised classification techniques have been
fruitfully applied to labeling and organizing large astronomical databases.
These methods require off-line classifier training, based on labeled examples
from each of the (known) object classes. In practice, only a small batch of
labeled examples, hand-labeled by a human expert, may be available for
training. Moreover, there may be no labeled examples for some classes present
in the data, i.e. the database may contain several unknown classes. Unknown
classes may be present due to 1) uncertainty in or lack of knowledge of the
measurement process, 2) an inability to adequately ``survey'' a massive
database to assess its content (classes), and/or 3) an incomplete scientific
hypothesis. In recent work, new class discovery in mixed labeled/unlabeled data
was formally posed, with a proposed solution based on mixture models. In this
work we investigate this approach, propose a competing technique suitable for
class discovery in neural networks, and evaluate both methods for
classification and class discovery on several astronomical data sets. Our
results demonstrate up to a 57% reduction in classification error compared to a
standard neural network classifier that uses only labeled data.


title: N-Body Growth of a Bahcall-Wolf Cusp Around a Black Hole

abstract:
  We present a clear N-body realization of the growth of a Bahcall-Wolf f ~
E^0.25 (rho ~ 1/r^1.75) density cusp around a massive object ("black hole") at
the center of a stellar system. Our N-body algorithm incorporates a novel
implementation of Mikkola-Aarseth chain regularization to handle close
interactions between star and black hole particles. Forces outside the chain
were integrated on a GRAPE-6A/8 special-purpose computer with particle numbers
up to N=0.25 x 10^6. We compare our N-body results with predictions of the
isotropic Fokker-Planck equation and verify that the time dependence of the
density (both configuration and phase-space) predicted by the Fokker-Planck
equation is well reproduced by the N-body algorithm, for various choices of N
and of the black hole mass. Our results demonstrate the feasibility of
direct-force integration techniques for simulating the evolution of galactic
nuclei on relaxation time scales.


title:
The Discovery of a Hyperluminal Source in the Radio Afterglow of GRB
  030329

abstract:
  Taylor, Frail, Berger and Kulkarni have made precise VLBI measurements of the
size and position of the source of the radio afterglow of GRB 030329. They
report a size evolution compatible with standard fireball models, proper motion
limits inconsistent with the cannonball model, and a double source, i.e. "an
additional compact component" on day 51 after the GRB, totally unexpected in
the standard models. We outline a consistent interpretation of the ensemble of
the data in the realm of the cannonball model. The observed double source is a
radio image of the two cannonballs required in this model to explain the
gamma-ray and optical light curves of this GRB; their separation agrees with
the expectation. Thus interpreted, the observation of the two sources
--separated by a "hyperluminal" distance-- is a major discovery in
astrophysics: it pins down the origin of GRBs.


title: Deep 3.8 micron Observations of the Trapezium Cluster

abstract:
  We present deep 3.8 micron observations of the Trapezium cluster in Orion
obtained with the ESO VLT. We use these data to search for infrared excess
emission and evidence for protoplanetary disks associated with the faint,
substellar population of this young cluster, and to investigate the nature and
extent of a recently discovered population of deeply embedded sources located
in dense molecular gas behind the cluster. Examining the infrared colors of 38
luminosity and 24 spectroscopically selected substellar candidates we determine
an infrared excess fraction of 50+/-20% from the JHKsLp colors for both
samples. This finding confirms the presence of infrared excess, likely due to
circumstellar disks, around a significant fraction of the cluster's substellar
population. Our deep Lp imaging survey also provides new information concerning
the deeply embedded population of young objects located in the molecular cloud
behind the cluster; in particular, it doubles the number of sources in the
cluster region known to possess extremely red K-L colors. These objects exhibit
K-Lp colors indicative of deeply buried, possibly protostellar, objects that
likely mark the site of the most recent and ongoing star formation in the
region. We find the surface density distribution of the deeply embedded
population to follow that of the background molecular ridge and to be highly
structured, consisting of a string of at least 5 significant subclusters. These
subclusters may represent the primordial building blocks out of which the
cluster was and perhaps still is being assembled. These observations may thus
provide insights into the early stages of cluster formation and appear
consistent with recent simulations that suggest that the Trapezium cluster may
have formed from numerous but small primordial subclusters.


title: The Relation of Compact Groups of Galaxies with Larger-scale Structures

abstract:
  We show that Compact Groups of Galaxies (CGs) are frequently associated with
larger-scale structures, and such associations become more frequent for CGs
selected by the same criteria at higher redshifts. Our findings suggest that
CGs are an intrinsic part of the cosmological structure formation process and
are consistent with the LambdaCDM (or "concordance") model, but only if galaxy
formation is a biased process.


title:
Nonlinear theory of a "shear-current" effect and mean-field magnetic
  dynamos

abstract:
  The nonlinear theory of a "shear-current" effect in a nonrotating and
nonhelical homogeneous turbulence with an imposed mean velocity shear is
developed. The ''shear-current" effect is associated with the $\bar{\bf W} {\bf
\times} \bar{\bf J}$-term in the mean electromotive force and causes the
generation of the mean magnetic field even in a nonrotating and nonhelical
homogeneous turbulence (where $\bar{\bf W}$ is the mean vorticity and $\bar{\bf
J}$ is the mean electric current). It is found that there is no quenching of
the nonlinear "shear-current" effect contrary to the quenching of the nonlinear
$\alpha$-effect, the nonlinear turbulent magnetic diffusion, etc. During the
nonlinear growth of the mean magnetic field, the ''shear-current" effect only
changes its sign at some value $\bar{\bf B}_\ast$ of the mean magnetic field.
The magnitude $\bar{\bf B}_\ast$ determines the level of the saturated mean
magnetic field which is less than the equipartition field. It is shown that the
background magnetic fluctuations due to the small-scale dynamo enhance the
"shear-current" effect, and reduce the magnitude $\bar{\bf B}_\ast$. When the
level of the background magnetic fluctuations is larger than 1/3 of the kinetic
energy of the turbulence, the mean magnetic field can be generated due to the
"shear-current" effect for an arbitrary exponent of the energy spectrum of the
velocity fluctuations.


title:
Models of the ICM with Heating and Cooling: Explaining the Global and
  Structural X-ray Properties of Clusters

abstract:
  (Abridged) Theoretical models that include only gravitationally-driven
processes fail to match the observed mean X-ray properties of clusters. As a
result, there has recently been increased interest in models in which either
radiative cooling or entropy injection play a central role in mediating the
properties of the intracluster medium. Both sets of models give reasonable fits
to the mean properties of clusters, but cooling only models result in fractions
of cold baryons in excess of observationally established limits and the
simplest entropy injection models do not treat the "cooling core" structure
present in many clusters and cannot account for entropy profiles revealed by
recent X-ray observations. We consider models that marry radiative cooling with
entropy injection, and confront model predictions for the global and structural
properties of massive clusters with the latest X-ray data. The models
successfully and simultaneously reproduce the observed L-T and L-M relations,
yield detailed entropy, surface brightness, and temperature profiles in
excellent agreement with observations, and predict a cooled gas fraction that
is consistent with observational constraints. The model also provides a
possible explanation for the significant intrinsic scatter present in the L-T
and L-M relations and provides a natural way of distinguishing between clusters
classically identified as "cooling flow" clusters and dynamically relaxed
"non-cooling flow" clusters. The former correspond to systems that had only
mild levels (< 300 keV cm^2) of entropy injection, while the latter are
identified as systems that had much higher entropy injection. This is borne out
by the entropy profiles derived from Chandra and XMM-Newton.


title: Co-moving space density of X-ray-selected Active Galactic Nuclei

abstract:
  For measurement of the AGN luminosity function and its evolution, X-ray
selection samples all types of AGN and provides reduced obscuration bias in
comparison with UV-excess or optical surveys. The apparent decline in
optically-selected quasars above z~3 may be strongly affected by such a bias.
The Chandra Multiwavelength Project (ChaMP) is characterizing serendipitously
detected X-ray sources in a large number of fields with archival Chandra
imaging. We present a preliminary measure of the co-moving space density using
a sample of 311 AGN found in 23 ChaMP fields (~1.8 deg^2) supplemented with 57
X-ray bright AGN from the CDF-N and CDF-S. Within our X-ray flux (f(0.3-8.0
keV) > 4x10^-15 erg cm^-2 s^-1) and optical magnitude (r' < 22.5) limits, our
sample includes 14 broad emission line AGN at z > 3. Using this X-ray selected
sample, we detect a turnover in the co-moving space density of luminous type 1
AGN (log Lx > 44.5; units erg s^-1; measured in the 0.3-8.0 keV band and
corrected for Galactic absorption) at z > 2.5. Our X-ray sample is the first to
show a behavior similar to the well established evolution of the optical quasar
luminosity function. A larger sample of high redshift AGN and with a greater
fraction of identified sources, either spectroscopic or photometric, at faint
optical magnitudes (r' > 22.5) are required to remove the remaining uncertainty
in our measure of the X-ray luminosity function. We confirm that for z < 1,
lower luminosity AGN (log Lx < 44.5) are more prevalent by more than an order
of magnitude than those with high luminosity. We have combined the Chandra
sample with AGN from the ROSAT surveys to present a measure of the space
density of luminous type 1 AGN in the soft X-ray band (0.5-2.0 keV) which
confirms the broad band turnover described above.


title:
Constraining the Evolution of Dark Energy with a Combination of Galaxy
  Cluster Observables

abstract:
  We show that the abundance and redshift distribution ($dN/dz$) of galaxy
clusters in future high--yield cluster surveys, combined with the spatial power
spectrum ($P_c(k)$) of the same clusters, can place significant constraints on
the evolution of the dark energy equation of state, $w=w(a)$. We evaluate the
expected errors on $w_a=-dw/da$ and other cosmological parameters using a
Fisher matrix approach, and simultaneously including cluster structure
evolution parameters in our analysis. We study three different types of
forthcoming surveys that will identify clusters based on their X-ray emission
(such as DUO, the Dark Universe Observatory), their Sunyaev--Zel'dovich (SZ)
decrement (such as SPT, the South Pole Telescope), or their weak lensing (WL)
shear (such as LSST, the Large Synoptic Survey Telescope). We find that
combining the cluster abundance and power spectrum significantly enhances
constraints from either method alone. We show that the weak-lensing survey can
deliver a constraint as tight as $\Delta w_a \sim 0.1$ on the evolution of the
dark energy equation of state, and that the X-ray and SZ surveys each yield
$\Delta w_a \sim 0.4$ separately, or $\Delta w_a \sim 0.2$ when these two
surveys are combined. For the X-ray and SZ surveys, constraints on dark energy
parameters are improved by a factor of two by combining the cluster data with
cosmic microwave background (CMB) anisotropy measurements by Planck, but
degrade by a factor of two if the survey is required to solve simultaneously
for cosmological and cluster structure evolution parameters. The constraint on
$w_a$ from the weak lensing survey is improved by $\sim 25$% with the addition
of Planck data.


title:
Mid-Infrared IRS Spectroscopy of NGC 7331: A First Look at the SINGS
  Legacy

abstract:
  The nearby spiral galaxy NGC 7331 was spectrally mapped from 5-38um using all
modules of Spitzer's IRS spectrograph. A strong new dust emission feature,
presumed due to PAHs, was discovered at 17.1um. The feature's intensity is
nearly half that of the ubiquitous 11.3um band. The 7-14um spectral maps
revealed significant variation in the 7.7 and 11.3um PAH features between the
stellar ring and nucleus. Weak [OIV] 25.9um line emission was found to be
centrally concentrated in the nucleus, with an observed strength over 10% of
the combined neon line flux, indicating an AGN or unusually active massive star
photo-ionization. Two [SIII] lines fix the characteristic electron density in
the HII regions at n_e < ~200 cm^-3. Three detected H_2 rotational lines,
tracing warm molecular gas, together with the observed IR continuum, are
difficult to match with standard PDR models. Either additional PDR heating or
shocks are required to simultaneously match lines and continuum.


title: Automated classification of variable stars for ASAS 1-2 data

abstract:
  With the advent of surveys generating multi-epoch photometry and the
discovery of large numbers of variable stars, the classification of these stars
has to be automatic. We have developed such a classification procedure for
about 1700 stars from the variable star catalogue of ASAS 1-2 (All Sky
Automated Survey, Pojmanski 2000) by selecting the periodic ones and by
applying an unsupervised Bayesian classifier using parameters obtained through
a Fourier decomposition of the light curve. For irregular light curves we used
the period and moments of the magnitude distribution for the classification. In
the case of ASAS 1-2, 83% of variable objects are red giants. A general
relation between the period and amplitude is found for a large fraction of
those stars. The selection led to 302 periodic and 1429 semi-periodic stars
which are classified in 6 major groups: eclipsing binaries, "sinusoidal
curves", Cepheids, small amplitude red variables, SR and Mira stars. The type
classification error level is estimated to be about 7%.


title:
High- and low-frequency quasi-periodic oscillations in the X-ray light
  curves of the black hole transient H1743-322

abstract:
  We present a variability study of the black hole candidate and X-ray
transient H1743-322 during its 2003/2004 outburst. We analyzed five Rossi X-ray
Timing Explorer observations that were performed as part of a multi-wavelength
campaign, as well as six observations from the early rise of the outburst. The
source was observed in several black hole states and showed various types of
X-ray variability, including high frequency quasi-periodic oscillations (QPOs)
at 240 Hz and 160 Hz (i.e. with a 3:2 frequency ratio), several types of low
frequency QPOs, and strong variations on a time scale of a few hundred seconds.
The discovery of high frequency QPOs in H1743-322 supports predictions that
these QPOs should be more easily observed in high inclination systems. In one
of our observations we observed a transition in count rate and color, during
which we were able to follow the smooth evolution of the low-frequency QPOs
from type-B to type-A. We classify the X-ray observations and QPOs, and briefly
discuss the QPOs in terms of recently proposed models.


title:
Status of the connection between unidentified EGRET sources and
  supernova remnants: The case of CTA 1

abstract:
  In this paper we briefly comment on the observational status of the possible
physical association between unidentified EGRET sources and supernova remnants
(SNRs) in our Galaxy. We draw upon recent results presented in the review by
Torres et al. (Physics Reports, 2003), concerning molecular gas in the vicinity
of all 19 SNRs found to be positionally coincident with EGRET sources at low
Galactic latitudes. In addition, we present new results regarding the supernova
remnant CTA~1. Our findings disfavor the possibility of a physical connection
with the nearby (in projection) EGRET source. There remains possible, however,
that the compact object produced in the supernova explosion be related with the
observed $\gamma$-ray flux.


title:
A Modification To The Gaseous Pressure Gradients In Spherical Celestial
  Bodies: Effects Of The Thermal Motion

abstract:
  The atmospherical pressure gradients of spherical celestial bodies are very
important in astrophysics and other related areas. The classical form of the
gradient in a gravitation-dominated celestial body:
$\frac{dp}{dR}=-\frac{GM}{R^2}\rho$ has been widely adopted for quit a long
time. But, in this form, a factor has been neglected: the centrifugal force
that due to the thermal motion of gaseous particles in a centripetal force
field. The pressure gradient is actually caused by the ``effective weight''
$f_g^{^{\prime}}$ of gaseous particles but not by their real gravity $f_g$. For
this reason, a modified form of the pressure gradient is given in this paper.
Though the changes are very small in most celestial bodies, they may be not
negligible in theories of stars, accretion disks, and so on with a cumulative
effect.


title: A High Spatial Resolution Infrared View of the T Tauri Multiple System

abstract:
  We present the results of our monitoring study of the IR photometric and
spectroscopic variability of the T Tau multiple system. We also present data on
the apparent position of T Tau S with respect to T Tau N, and two new spatially
resolved observations of the T Tau Sa-Sb binary. T Tau N has not varied by more
than 0.2 magnitudes in K and L' flux during the 8 years of our observations,
though its Br gamma and Br alpha emission line fluxes have varied by nearly a
factor of four during this time. For the unresolved T Tau S system, we have
derived a 20 year light curve based on our images and on measurements available
in the literature. T Tau S varies by 2-3 magnitudes in K and L'-band brightness
in a ``redder when faint'' manner, consistent with changes along the line of
sight in the amount of material that follows an ISM extinction law. Absorption
in the 3.05um water-ice feature is seen only in the spectra of T Tau S and it
displays variations in depth and profile. H_2 (2.12 um) emission is also
detected only at the position of T Tau S; the H_2, Br gamma and Br alpha
emission line fluxes also vary. We have found that the apparent positions of T
Tau S with respect to T Tau N and T Tau Sb with respect to Sa are consistent
with gravitationally bound orbital motion. The possible orbits of the T Tau S
binary imply that Sa is likely the most massive component in this young triple.
A reanalysis of the motion of the radio source associated with T Tau S provides
no evidence for an ejection event in the T Tau system.


title: Do We Know of Any Maunder Minimum Stars?

abstract:
  Most stars previously identified as Maunder minimum stars are old stars
evolved off of the main sequence. Analysis of activity measurements from the
California and Carnegie Planet Search program stars and Hipparcos parallaxes
implies that the canonical age-chromospheric activity relation breaks down for
stars older than $\sim 6$ Gyr when activity is calculated from Mount Wilson S
values. Stars only 1 magnitude above the main sequence exhibit significantly
suppressed activity levels which have been mistaken for examples of Maunder
minimum behavior.


title:
Bending instabilities at the origin of persistent warps: a new
  constraint on dark matter halos

abstract:
  A substantial fraction of the warps in spiral galaxies may result from
bending instabilities if the disks are essentially self-gravitating. With
N-body simulations, we show that galaxies with self-gravitating disks as thick
as HI disks are subject to bending instabilities generating S-shaped, U-shaped
or asymmetric warps. S-shaped warps persist during several rotations and keep
the line of node straight. The warp amplitudes generated by bending
instabilities remain however modest. Other factors must be invoked for extreme
warped disks. However, bending instabilities can account for most of the cases
reported in optical surveys, where the warp angle is generally less than
$5^\circ$. This mode of warping is very sensitive to the disk flattening. It
also constrains the fraction of dark matter distributed in the disk and in the
dark halo.


title: First observation of Jupiter by XMM-Newton

abstract:
  We present the first X-ray observation of Jupiter by XMM-Newton. Images taken
with the EPIC cameras show prominent emission, essentially all confined to the
0.2-2.0 keV band, from the planet's auroral spots; their spectra can be
modelled with a combination of unresolved emission lines of highly ionised
oxygen (OVII and OVIII), and a pseudo-continuum which may also be due to the
superposition of many weak lines. A 2.8 sigma enhancement in the RGS spectrum
at 21-22 A (~0.57 keV) is consistent with an OVII identification. Our spectral
analysis supports the hypothesis that Jupiter's auroral emissions originate
from the capture and acceleration of solar wind ions in the planet's
magnetosphere, followed by X-ray production by charge exchange. The X-ray flux
of the North spot is modulated at Jupiter's rotation period. We do not detect
evidence for the ~45 min X-ray oscillations observed by Chandra more than two
years earlier. Emission from the equatorial regions of the planet's disk is
also observed. Its spectrum is consistent with that of scattered solar X-rays.


title:
Photometric variability of young brown dwarfs in the sigma Orionis open
  cluster

abstract:
  We have carried out multi-epoch, time-series differential I-band photometry
of a large sample of objects in the south-east region of the young (~3 Myr),
nearby (~350 pc) sigma Orionis open cluster. A field of ~1000 arcmin^2 was
monitored during four nights over a period of two years. Using this dataset, we
have studied the photometric variability of twenty-eight brown dwarf cluster
candidates with masses ranging from the stellar-substellar boundary down to the
planetary-mass domain. We have found that about 50% of the sample show
photometric variability on timescales from less than one hour to several days
and years. The amplitudes of the I-band light curves range from less than 0.01
up to ~0.4 magnitudes. A correlation between the near-infrared excess in the
K_s band, strong Halpha emission and large-amplitude photometric variation is
observed. We briefly discuss how these results may fit the different scenarios
proposed to explain the variability of cool and ultracool dwarfs (i.e. magnetic
spots, patchy obscuration by dust clouds, surrounding accretion discs and
binarity). Additionally, we have determined tentative rotational periods in the
range 3 to 40 h for three objects with masses around 60 M_Jup, and the
rotational velocity of 14+/-4 km/s for one of them.


title: The Nuclear Gas Dynamics and Star Formation of Markarian 231

abstract:
  We report adaptive optics H- and K-band spectroscopy of the inner few arcsec
of the luminous merger/ULIRG/QSO Mkn231, at spatial resolutions as small as
0.085". For the first time we have been able to resolve the active star forming
region close to the AGN using stellar absorption features, finding that its
luminosity profile is well represented by an exponential function with a disk
scale length 0.18-0.24" (150-200pc), and implying that the stars exist in a
disk rather than a spheroid. The stars in this region are also young
(10-100Myr), and it therefore seems likely that they have formed in situ in the
gas disk, which itself resulted from the merger. The value of the stellar
velocity dispersion is a result of the large mass surface density of the disk.
The stars in this region have a combined mass of at least 1.6x10^9M_sun, and
account for 25-40% of the bolometric luminosity of the entire galaxy. We have
detected the 2.12um 1-0S(1) H_2 and 1.64um [FeII] lines out to radii exceeding
0.5". The kinematics for the two lines are very similar to each other as well
as to the stellar kinematics, and broadly consistent with the nearly face-on
rotating disk reported in the literature and based on interferometric CO1-0 and
CO2-1 measurements of the cold gas. However, they suggest a more complex
situation in which the inner 0.2-0.3" (200pc) is warped out of its original
disk plane. Such a scenario is supported by other observations.


title: Probing galaxy density profiles with future supernova surveys

abstract:
  In this paper we discuss the possibility to measure the Hubble parameter and
the slope of galaxy density profiles using future supernova data. With future
supernova surveys such as SNAP, large numbers of core collapse supernovae will
be discovered, a small fraction of which will be multiply imaged. Measurements
of the image separation, flux-ratio, time-delay and lensing foreground galaxy
for these systems will provide tight constraints on the slope of galactic halos
as well as providing complementary and independent information to other
cosmological tests with respect to the Hubble parameter.


title:
Chandra observations of the massive star-forming region S106: X-ray
  emission from the embedded massive protostellar object IRS 4

abstract:
  We present Chandra observations of the massive star-forming region S106, a
prominent HII region in Cygnus, associated with an extended molecular cloud and
a young cluster. The nebula is excited by a single young massive star located
at the center of the molecular cloud and the embedded cluster. The prominence
of the cluster in the Chandra observation presented here confirms its youth and
allows some of its members to be studied in more detail. We detect X-ray
emission from the young massive central source S106 IRS 4, the deeply embedded
central object which drives the bipolar nebula with a mass loss rate
approximately 1-2 orders of magnitude higher than main sequence stars of
comparable luminosity. Still, on the basis of its wind momentum flux the X-ray
luminosity of S106 IRS 4 is comparable to the values observed in more evolved
(main sequence and giant) massive stars, suggesting that the same process which
is responsible for the observed X-ray emission from older massive stars is
already at work at these early stages.


title:
The XMM-Newton/2dF survey VII. Is there any X-ray absorption in
  optically selected QSOs?

abstract:
  We explore the X-ray properties of optically selected QSOs spectroscopically
identified in the course of the 2dF QSO survey (2QZ). Our main goal is to
expand to higher redshifts previous findings suggesting the presence of a
fraction of X-ray obscured sources among the low redshift optically selected
broad line AGN population. The X-ray data are from the wide field (~2.5 sq.
deg), shallow $[f(0.5 - 8 keV) ~10^-14 egs s^-1 cm^-2 XMM-Newton/2dF survey. A
total of 96 2QZ QSOs overlap with the area covered by our X-ray survey. 66 of
them have X-ray counterparts while 30 remain undetected in our X-ray survey.
The 66 X-ray detected QSOs have a mean photon index of ~2 suggesting little or
no X-ray obscuration for most of these sources. Individual X-ray spectral
fittings reveal only 1 source (intrinsic Lx(0.5-8 keV) ~ 10^44 erg s^-1 at
z=0.82) that is likely to be obscured (NH~10^23 cm^-2) at the 90% confidence
level. Additionally, there are 9 2QZ sources that show evidence for moderate
absorption (mean observed NH of ~10^21 cm^-2). For the 30 QSOs that remain
undetected in our X-ray survey we use stacking analysis to estimate a mean
hardness ratio of -0.59 +/- 0.11 suggesting that the bulk of this population
has NH consistent with the Galactic value. However, we cannot exclude the
possibility that some of these sources have enhanced photoelectric absorption
that is not revealed in the mean stacked spectrum. We estimate a lower limit to
the fraction of optically selected QSO with X-ray absorption of about 10% (10
out of 96).


title: On the use of photometric redshifts for X-ray selected AGNs

abstract:
  (Abridged) In this paper we present photometric redshift estimates for a
sample of X-ray selected sources detected in the wide field (~2 deg^2), bright
[f_{X} (0.5-8 keV)~10^{-14} cgs] XMM-Newton/2dF survey. Unlike deeper X-ray
samples comprising a large fraction of sources with colours dominated by the
host galaxy, our bright survey primarily probes the QSO X-ray population.
Therefore photometric redshift methods employing both galaxy and QSO templates
need to be used. We employ the photometric redshift technique of
Hatziminaoglou, Mathez & Pello (2000) using 5-band photometry from the SDSS. We
separate our X-ray sources according to their optical profile to point-like and
extended. We apply QSO and galaxy templates to the point-like and extended
sources respectively. X-ray sources associated with Galactic stars are
identified and discarded from our point-like sample on the basis of their low
X-ray--to--optical flux ratio and their broad band colours that are best fit by
stellar templates. Comparison of our results with spectroscopic redshifts
available, allows calibration of our method and estimation of the photometric
redshift accuracy. For ~70 per cent of the point-like sources photometric
redshifts are correct within dz <= 0.3 (or ~75 per cent have dz/(1+z) <= 0.2),
and the rms scatter is estimated to be sigma_z = 0.30. For the optically
extended objects the photometric redshifts work only in the case of red (g - r
> 0.5 mag) sources yielding dz <= 0.15 and dz/(1+z) <= 0.2 for 73 and 93 per
cent respectively. However, we find that the above photometric redshift
technique does not work in the case of extended sources with blue colours (g -
r < 0.5): such sources cannot be fit successfully by QSO or galaxy templates,
or any linear combination of the two.


title:
X-ray emission from the nuclei, lobes and hot-gas environments of two
  FR-II radio galaxies

abstract:
  We report the detection of multiple components of X-ray emission from the two
FR-II radio galaxies 3C 223 and 3C 284, based on new XMM-Newton observations.
We attribute the detected X-ray emission from the lobes of both sources to
inverse-Compton scattering of cosmic microwave background photons. With this
model, we find that the magnetic field strength in the lobes is at the
equipartition value for 3C 284, and within a factor of two of the equipartition
value for 3C 223. We also detect group-scale hot atmospheres around both
sources, and determine temperatures and pressures in the gas. The lobes of both
sources are in pressure balance with the hot-gas environments, if the lobes
contain only the synchrotron-emitting particles and the measured magnetic field
strength. The core spectra of both sources contain an unabsorbed soft
component, likely to be related to the radio jet, and an additional heavily
absorbed power-law component. 3C 223 also displays a bright (EW ~ 500 eV) Fe
K-alpha emission line.


title:
The photospheric abundances of active binaries III. Abundance
  peculiarities at high activity level

abstract:
  We report the determination from high-resolution spectra of the atmospheric
parameters and abundances of 13 chemical species (among which lithium) in 8
single-lined active binaries. These data are combined with our previous results
for 6 other RS CVn systems to examine a possible relationship between the
photospheric abundance patterns and the stellar activity level. The stars
analyzed are generally found to exhibit peculiar abundance ratios compared to
inactive, galactic disk stars of similar metallicities. We argue that this
behaviour is unlikely an artefact of errors in the determination of the
atmospheric parameters or non-standard mixing processes along the red giant
branch, but diagnoses instead the combined action of various physical processes
related to activity. The most promising candidates are cool spot groups
covering a very substantial fraction of the stellar photosphere or NLTE effects
arising from nonthermal excitation. However, we cannot exclude the possibility
that more general shortcomings in our understanding of K-type stars (e.g.
inadequacies in the atmospheric models) also play a significant role. Lastly,
we call attention to the unreliability of the (V-R) and (V-I) colour indices as
temperature indicators in chromospherically active stars.


title: Parsec-scale X-ray Flows in High-mass Star-forming Regions

abstract:
  We present Chandra/ACIS images of several high-mass star-forming regions. The
massive stellar clusters powering these HII regions are resolved at the
arcsecond level into hundreds of stellar sources, similar to those seen in
closer young stellar clusters. However, we also detect diffuse X-ray emission
on parsec scales that is spatially and spectrally distinct from the point
source population. For nearby regions (e.g. M17 and Rosette) the emission is
soft, with plasma temperatures less than 10 million degrees, in contrast to
what is seen in more distant complexes (e.g. RCW49, W51).
  This extended emission most likely arises from the fast O-star winds
thermalized either by wind-wind collisions or by a termination shock against
the surrounding media. We have established that only a small portion of the
wind energy and mass appears in the observed diffuse X-ray plasma; in the
blister HII regions, we suspect that most of it flows without cooling into the
low-density interstellar medium through blow-outs or fissures in the
surrounding neutral material. These data provide compelling observational
evidence that strong wind shocks are present in HII regions.


title:
The distance to the Sgr dwarf spheroidal galaxy from the Red Giant
  Branch Tip

abstract:
  We derived the distance to the central region of the Sagittarius dwarf
spheroidal galaxy from the Red Giant Branch Tip. The obtained distance modulus
is $(m-M)_0=17.10\pm0.15$, corresponding to a heliocentric distance
$D=26.30\pm1.8$ Kpc. This estimate is in good agreement with the distance
obtained from RR Lyrae stars of the globular cluster M~54, located in the core
of the Sgr galaxy, once the most accurate estimate of the cluster metallicity
and the most recent calibration of the $M_V(RRLy) vs.[Fe/H]$ relation are
adopted.


title:
Infrared Properties of Radio-Selected Submillimeter Galaxies in the
  Spitzer First Look Survey Verification Field

abstract:
  We report on submillimeter and infrared observations of 28 radio-selected
galaxies in the Spitzer First Look Survey Verification field (FLSV). All of the
radio-selected galaxies that show evidence for emission at 850um with SCUBA
have Spitzer counterparts at 24um, while only half of the radio-selected
galaxies without 850um emission have detectable counterparts at 24um. The data
show a wide range of infrared colors (S70/S24 < 5--30, S8/S3.6 < 0.3--4),
indicative of a mixture of infrared-warm AGN and cooler starburst dominated
sources. The galaxies showing 850um emission have Spitzer flux densities and
flux density ratios consistent with the range of values expected for
high-redshift (z=1--4) ultraluminous infrared galaxies.


title: The Submillimeter Array

abstract:
  The Submillimeter Array (SMA), a collaborative project of the Smithsonian
Astrophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy
and Astrophysics (ASIAA), has begun operation on Mauna Kea in Hawaii. A total
of eight 6-m telescopes comprise the array, which will cover the frequency
range of 180-900 GHz. All eight telescopes have been deployed and are
operational. First scientific results utilizing the three receiver bands at
230, 345, and 690 GHz have been obtained and are presented in the accompanying
papers.


title:
Energetics of Black Hole-Accretion Disk System with Magnetic Connection:
  Limit of Low Accretion Rate

abstract:
  We study the energetics of a black hole-accretion disk system with magnetic
connection: a Keplerian disk is connected to a Kerr black hole by a large-scale
magnetic field going through the transition region. We assume that the magnetic
field is locked to the inner boundary of the disk and corotates with the inner
boundary, the accretion rate is low but the accretion from the disk can still
provide enough amount of cold plasma particles in the transition region so that
the magnetohydrodynamics approximation is valid. Then, the magnetic field is
dynamically important in the transition region and affects the transportation
of energy and angular momentum. Close to the equatorial plane, the motion of
particles is governed by a one-dimensional radial momentum equation, which
contains a fast critical point as the only intrinsic singularity. By finding
solutions that smoothly pass the fast critical point, we find that a system
with a fast rotating black hole and that with a slow rotating black hole behave
very differently. For a black hole with $a > a_{\rm cr}\equiv 0.3594 M$, where
$M$ is the mass, $a$ the specific angular momentum of the black hole, the
spinning energy of the black hole is efficiently extracted by the magnetic
field and transported to the disk, increasing the radiation efficiency of the
disk by many orders of magnitude. For a black hole with $0\leq a < a_{\rm cr}$,
the inner region of the disk is disrupted by the magnetic field and the inner
boundary of the disk moves out to a radius where the Keplerian angular velocity
of the disk is equal to the spinning angular velocity of the black hole (which
is at infinity if the black hole is nonrotating). As a result, the disk may
have an extremely low radiation efficiency if $0\leq a/M \ll 1$.


title:
Statistical Isotropy of the Wilkinson Microwave Anisotropy Probe Data: A
  Bipolar Power Spectrum Analysis

abstract:
  The statistical expectation values of the temperature fluctuations of the
Cosmic Microwave Background (CMB) are assumed to be preserved under rotations
of the sky. We investigate the Statistical Isotropy (SI) of the CMB anisotropy
maps recently measured by the Wilkinson Microwave Anisotropy Probe (WMAP) using
Bipolar Power Spectrum (BiPS) proposed in [Hajian & Souradeep 2003]. The method
can probe specific regions in multipole space using appropriate window
functions. The BiPS is estimated for full sky CMB anisotropy maps based on the
first year WMAP data using a range of window functions. The BiPS spectra
computed for both full sky maps for all our window functions are consistent
with zero, roughly within $2 \sigma$. The null BiPS results may be interpreted
as an absence of strong violation of statistical isotropy in the first-year
WMAP data on angular scales larger than that corresponding to $l\sim60$.
However, pending a careful direct comparison, our results do not necessarily
conflict with the specific SI related anomalies reported using other
statistical tests.


title: Dark-Matter Electric and Magnetic Dipole Moments

abstract:
  We consider the consequences of a neutral dark-matter particle with a nonzero
electric and/or magnetic dipole moment. Theoretical constraints, as well as
constraints from direct searches, precision tests of the standard model, the
cosmic microwave background and matter power spectra, and cosmic gamma rays,
are included. We find that a relatively light particle with mass between an MeV
and a few GeV and an electric or magnetic dipole as large as $\sim 3\times
10^{-16}e$ cm (roughly $1.6\times10^{-5} \mu_B$) satisfies all experimental and
observational bounds. Some of the remaining parameter space may be probed with
forthcoming more sensitive direct searches and with the Gamma-Ray Large Area
Space Telescope.


title: Resolved Inner Disks around Herbig Ae/Be Stars

abstract:
  We have observed 14 Herbig Ae/Be sources with the long-baseline near-IR
Palomar Testbed Interferometer, All except two sources are resolved at 2.2 um,
with angular sizes generally <5 mas. We determine the size scales and
orientations of the 2.2 um emission using various models: uniform disks,
Gaussians, uniform rings, flat accretion disks with inner holes, and flared
disks with puffed-up inner rims; 7 objects display significantly inclined
morphologies, generally compatible with the outer disk geometries inferred from
millimeter interferometric observations, implying that HAEBE disks are not
significantly warped. Using the derived inner disk sizes and inclinations, we
compute the spectral energy distributions for two simple physical disk models,
and compare these with observed SEDs compiled from the literature and new
near-IR photometry. While geometrically flat accretion disk models are
consistent with the data for the earliest spectral types in our sample (MWC
297, V1685 Cyg, and MWC 1080), the later-type sources are explained better
through models incorporating puffed-up inner disk walls; this may indicate
different accretion mechanisms for early and late-type Herbig Ae/Be stars.


title: The Clustering of AGN in the Sloan Digital Sky Survey

abstract:
  We present the two--point correlation function (2PCF) of narrow-line active
galactic nuclei (AGN) selected within the First Data Release of the Sloan
Digital Sky Survey. Using a sample of 13605 AGN in the redshift range 0.055 < z
< 0.2, we find that the AGN auto--correlation function is consistent with the
observed galaxy auto--correlation function on scales 0.2h^{-1}Mpc to
>100h^{-1}Mpc. The AGN hosts trace an intermediate population of galaxies and
are not detected in either the bluest (youngest) disk--dominated galaxies or
many of the reddest (oldest) galaxies. We show that the AGN 2PCF is dependent
on the luminosity of the narrow [OIII] emission line (L_{[OIII]}), with low
L_{[OIII]} AGN having a higher clustering amplitude than high L_{[OIII]} AGN.
This is consistent with lower activity AGN residing in more massive galaxies
than higher activity AGN, and L_{[OIII]} providing a good indicator of the
fueling rate. Using a model relating halo mass to black hole mass in
cosmological simulations, we show that AGN hosted by ~ 10^{12} M_{odot} dark
matter halos have a 2PCF that matches that of the observed sample. This mass
scale implies a mean black hole mass for the sample of M_{BH} ~ 10^8 M_{odot}.


title: The Cosmic Microwave Background and Its Polarization

abstract:
  The DASI discovery of CMB polarization, confirmed by WMAP, has opened a new
chapter in cosmology. Most of the useful information about inflationary
gravitational waves and reionization is on large angular scales where Galactic
foreground contamination is the worst. The goal of the present review is to
provide the state-of-the-art of the CMB polarization from a practical point of
view, connecting real-world data to physical models. We present the physics of
this polarized phenomena and illustrate how it depends of various cosmological
parameters for standard adiabatic models. We also present all observational
constraints to date and discuss how much we have learned about polarized
foregrounds so far from the CMB studies. Finally, we comment on future
prospects for the measurement of CMB polarization.


title:
SPITZER Observations of the SCUBA/VLA Sources in the Lockman Hole: Star
  Formation History of Infrared-Luminous Galaxies

abstract:
  We present Spitzer IRAC (3.6, 4.5, 5.8, 8.0 um) and MIPS (24 um) observations
of the SCUBA submillimeter sources and uJy VLA radio sources in a 5'x5' area in
the Lockman Hole East region. Out of the ~40 SCUBA/VLA sources in the field,
Spitzer counterparts were detected for nearly all except for the few low-weight
SCUBA detections. We show that the majority (80-90%) of the detected sources
are cold (i.e., starburst-like) infrared-luminous galaxies (L_{IR} > 10^{11}
Lsun) at redshift 0.5<z<3.5, whose star-formation rate density (SFRD) is
comparable to that of the optically-selected star-forming galaxies.