title: Cosmic ray feedback in hydrodynamical simulations of galaxy formation

abstract:
  It is well known that cosmic rays (CRs) contribute significantly to the
pressure of the interstellar medium in our own Galaxy, suggesting that they may
play an important role in regulating star formation during the formation and
evolution of galaxies. We here discuss a novel numerical treatment of the
physics of CRs and its implementation in the parallel smoothed particle
hydrodynamics code GADGET-2. In our methodology, the non-thermal CR population
of each gaseous fluid element is approximated by a simple power law spectrum in
particle momentum, characterized by an amplitude, a cut-off, and a fixed slope.
Adiabatic compression, and a number of physical source and sink terms are
modelled which modify the CR pressure of each particle. The most important
sources considered are injection by supernovae and diffusive shock
acceleration, while the primary sinks are thermalization by Coulomb
interactions, and catastrophic losses by hadronic interactions. We also include
diffusion of CRs. Our scheme allows us to carry out the first cosmological
structure formation simulations that self-consistently account for CR physics.
In simulations of isolated galaxies, we find that CRs can significantly reduce
the star formation efficiencies of small galaxies, with virial velocities below
\~80 km/s, an effect that becomes progressively stronger towards low mass
scales. In cosmological simulations at high redshift, the total mass-to-light
ratio of small halos and the faint-end of the luminosity function are strongly
affected. When CR acceleration in shocks is followed as well, up to ~40% of the
energy dissipated at structure formation shocks can appear as CR pressure at
z~3-6, but this fraction drops to ~10% at low redshifts when the shock
distribution becomes increasingly dominated by lower Mach numbers. (abridged)


title: Willman 1 - A Galactic Satellite at 40 kpc With Multiple Stellar Tails

abstract:
  SDSSJ1049+5103, commonly known as Willman 1, is an extremely low-luminosity
Milky Way companion whose properties are intermediate between those of globular
clusters and dwarf spheroidals. In this paper, we use deep photometry to show
that this object is old and moderately metal-poor, has a distance of 38 +/- 7
kpc, has an M_V of -2.5 mag, and has a half-light radius of 21 +/- 7 pc,
consistent with previous estimates. The spatial distribution of Willman 1's
main sequence stars shows 1) its total spatial extent exceeds its tidal radius
for a range of assumptions about its total mass and its orbit and 2) the
presence of prominent multi-directional stellar tails. The tidal interactions
causing these tail features may explain the large physical size of Willman 1
relative to low-luminosity globular clusters. It is the most distant Galactic
object yet known to display prominent tails, and is the only distant satellite
to display multi-directional tails. Although we cannot at present determine the
cause of this unusual morphology, preliminary comparisons between the
morphology of Willman 1 and published simulations suggest that it may be near
the apocenter of its orbit, or that it may have interacted with another halo
object. We find a significant difference between the luminosity functions of
stars in the center and in the tails of Willman 1, strongly suggesting mass
segregation much like that seen in Palomar 5. Although Willman 1 has more
pronounced tidal tails than most confirmed Milky Way dwarf galaxies, because of
its very low stellar mass we cannot at present rule out the possibility that it
has a dark matter halo. (Abridged)


title:
Growing Live Disks Within Cosmologically Assembling Asymmetric Halos:
  Washing Out the Halo Prolateness

abstract:
  We study the growth of galactic disks in live triaxial DM halos. The halos
have been assembled through constrained realizations method and evolved from
the linear regime using cosmological simulations. The `seed' disks have been
inserted at redshift z=3 and increased in mass tenfold over various time
periods, ~1-3 Gyr, with the halo responding quasi-adiabatically to this
process. We follow the dynamical and secular evolution of the disk-halo system
and analyze changes in the most important parameters, like 3-D DM shapes,
stellar and DM radial density profiles, stellar bar development, etc. We find
that a growing disk is responsible for washing out the halo prolateness and for
diluting its flatness over a period of time comparable to the disk growth.
Moreover, we find that a disk which contributes more to the overall rotation
curve in the system is also more efficient in axisymmetrizing the halo, without
accelerating the halo figure rotation. The observational corollary is that the
maximal disks probably reside in nearly axisymmetric halos, while disks whose
rotation is dominated by the halo at all radii are expected to reside in more
prolate halos. The halo shape is sensitive to the final disk mass, but is
independent of how the seed disk is introduced into the system. We also expect
that the massive disks are subject to a bar instability, while light disks have
this instability damped by the halo triaxiality. Implications to the
cosmological evolution of disks embedded in asymmetric halos are discussed and
so are the corollaries for the observed fraction of stellar bars. Finally, the
halo responds to the stellar bar by developing a gravitational wake -- a
`ghost' bar of its own which is almost in-phase with that in the disk.


title:
The Spitzer Space Telescope Extra-Galactic First Look Survey: 24 micron
  data reduction, catalog, and source identification

abstract:
  We present the reduction of the 24 micron data obtained during the first
cosmological survey performed by the Spitzer Space Telescope (First Look
Survey, FLS). The survey consists of a shallow observation of 2.5x2 sq deg
centered at 17h18m +59d30m (main survey) and a deeper observation of 1x0.5 sq
deg centered at 17h17m +59d45m(verification survey). Issues with the reduction
of the 24 micron MIPS data are discussed and solutions to attenuate
instrumental effects are proposed and applied to the data. Approximately 17000
sources are extracted with a SNR greater than five. The photometry of the point
sources is evaluated through PSF fitting using an empirical PSF derived from
the data. Aperture corrections and the absolute calibration have been checked
using stars in the field. Astrometric and photometric errors depend on the SNR
of the source varying between 0.35-1 arcsec and 5-15%, respectively, for
sources detected at 20-5 sigma. The flux of the 123 extended sources have been
estimated through aperture photometry. The extended sources cover less than
0.3% of the total area of the survey. Based on simulations, the main and
verification surveys are 50% complete at 0.3 and 0.15 mJy, respectively.
Counterparts have been searched for in optical and radio catalogs. More than
80% of the 24 micron sources have a reliable optical counterpart down to
R=25.5. 16% of the sources have a 20 cm counterpart down to 0.1 mJy and ~ 80%
of the radio-infrared associations have a reliable optical counterpart. A
residual map is obtained by subtracting point sources detected at the 3-sigma
level and interpolating the regions occupied by extended sources. Several
galactic clouds with low and intermediate velocities are identified by
comparison with neutral Hydrogen data from this field.


title: Diffraction of Apodized Pupil Mapping Systems with Aberrations

abstract:
  Pupil mapping is a promising and unconventional new method for high contrast
imaging being considered for terrestrial exoplanet searches. It employs two (or
more) specially designed aspheric mirrors to create a high-contrast amplitude
profile across the telescope pupil that does not appreciably attenuate
amplitude. As such, it reaps significant benefits in light collecting
efficiency and inner working angle, both critical parameters for terrestrial
planet detection. While much has been published on various aspects of pupil
mapping systems, the problem of sensitivity to wavefront aberrations remains an
open question. In this paper, we present an efficient method for computing the
sensitivity of a pupil mapped system to Zernike aberrations. We then use this
method to study the sensitivity of a particular pupil mapping system and
compare it to the concentric-ring shaped pupil coronagraph. In particular, we
show how contrast and inner working angle degrade with increasing Zernike order
and rms amplitude, which has obvious ramifications for the stability
requirements and overall design of a planet-finding observatory.


title: Interstellar Scintillation of PSR J0437-4715

abstract:
  We studied the turbulence spectrum of the local interstellar plasma in the
direction of PSR J0437-4715, on the basis of our observations and those
reported earlier by others. We combine these data to form a structure function
for the variations of phase along the line of sight to the pulsar. For
observations that did not report them, we infer modulation indices from a
theoretical model. We find that all of the observations fit a power-law
spectrum of turbulence with index n=3.46+/-0.20. We suggest that differences
among reported values for scintillation bandwidth and timescale for this pulsar
arise from differences in observing parameters. We suggest that refractive
effects dominate for this line of sight, with refraction angle about twice the
diffraction angle at 330 MHz observing frequency. We suggest that the
scattering of this pulsar lies in a layer of enhanced turbulence, about 10 pc
from the Sun. We propose that the flux variations of the extragalactic source
PKS 0405-385 arise in the same scattering layer.


title: Local Group Dwarf Galaxies and the Fundamental Manifold of Spheroids

abstract:
  The fundamental manifold (FM), an extension of the fundamental plane
formalism, incorporates all spheroid-dominated stellar systems from dwarf
ellipticals up to the intracluster stellar populations of galaxy clusters by
accounting for the continuous variation of the mass-to-light ratio within the
effective radius r_e with scale. Here, we find that Local Group dwarf
spheroidal and dwarf elliptical galaxies, which probe the FM relationship
roughly one decade lower in r_e than previous work, lie on the extrapolation of
the FM. When combined with the earlier data, these Local Group dwarfs
demonstrate the validity of the empirical manifold over nearly four orders of
magnitude in r_e. The continuity of the galaxy locus on the manifold and, more
specifically, the overlap on the FM of dwarf ellipticals like M 32 and dwarf
spheroidals like Leo II, implies that dwarf spheroidals belong to the same
family of spheroids as their more massive counterparts. The only significant
outliers are Ursa Minor and Draco. We explore whether the deviation of these
two galaxies from the manifold reflects a breakdown in the coherence of the
empirical relationship at low luminosities or rather the individual dynamical
peculiarities of these two objects. We discuss some implications of our results
for how the lowest mass galaxies form.


title:
High-Resolution Absorption Spectroscopy of Multi-phase, High-Metallicity
  Gas Associated with the Luminous Quasar HE 0226-4110

abstract:
  We present FUSE and HST/STIS observations of the absorption line system near
the emission redshift of the radio-quiet, X-ray bright quasar HE0226-4110 (z =
0.495, V=15.2). The spectra cover the rest-frame wavelength range 610--1150 A,
and we detect a wide range of ionization species, including four adjacent
stages of oxygen (O III-VI), which reveal a striking change in gas kinematics
with ionization. Examination of the O VI 1031, 1037 doublet profiles reveals no
evidence for partial coverage or unresolved saturated structure. O III is only
detected in a narrow feature which is also traced by H I and C III, suggesting
that they arise in the same gas. Absorption at the same velocity is also
present in other species N IV, O IV-VI, S IV, and possibly N VIII, but the
kinematics differ from the O III, implying production in separate gaseous
phases. The H I, O II-IV, and C III information in yield an estimate of both
the photoionization parameter and metallicity of the O III-bearing gas:
[O/H]=+0.12(-0.03/+0.16), log U=-2.29(-0.23/+0.02). We discuss two possible
locations for the gas in this associated absorption-line system: the narrow
emission line region of the quasar, and the halo of the quasar host galaxy. An
additional narrow (thus, photoionized) component that is only detected in O VI
appears 58 km/s redward of the O III-bearing gas with -0.35 < log U < 0.02.
Additional structure is detected in the associated absorber in the form of two
broad components which only appear in moderate to high ionization species.
[highly abridged]


title:
Inverting Color-Magnitude Diagrams to Access Precise Star Cluster
  Parameters: A Bayesian Approach

abstract:
  We demonstrate a new Bayesian technique to invert color-magnitude diagrams of
main sequence and white dwarf stars to reveal the underlying cluster properties
of age, distance, metallicity, and line-of-sight absorption, as well as
individual stellar masses. The advantages our technique has over traditional
analyses of color-magnitude diagrams are objectivity, precision, and explicit
dependence on prior knowledge of cluster parameters. Within the confines of a
given set of often-used models of stellar evolution, the initial-final mass
relation, and white dwarf cooling, and assuming photometric errors that one
could reasonably achieve with the Hubble Space Telescope, our technique yields
exceptional precision for even modest numbers of cluster stars. For clusters
with 50 to 400 members and one to a few dozen white dwarfs, we find typical
internal errors of sigma([Fe/H]) <= 0.03 dex, sigma(m-M) <= 0.02 mag, and
sigma(Av) <= 0.01 mag. We derive cluster white dwarf ages with internal errors
of typically only 10% for clusters with only three white dwarfs and almost
always <= 5% with ten white dwarfs. These exceptional precisions will allow us
to test white dwarf cooling models and standard stellar evolution models
through observations of white dwarfs in open and globular clusters.


title: Massive neutrinos and cosmology

abstract:
  The present experimental results on neutrino flavour oscillations provide
evidence for non-zero neutrino masses, but give no hint on their absolute mass
scale, which is the target of beta decay and neutrinoless double-beta decay
experiments. Crucial complementary information on neutrino masses can be
obtained from the analysis of data on cosmological observables, such as the
anisotropies of the cosmic microwave background or the distribution of
large-scale structure. In this review we describe in detail how free-streaming
massive neutrinos affect the evolution of cosmological perturbations. We
summarize the current bounds on the sum of neutrino masses that can be derived
from various combinations of cosmological data, including the most recent
analysis by the WMAP team. We also discuss how future cosmological experiments
are expected to be sensitive to neutrino masses well into the sub-eV range.


title: Supernova 2006aj and the associated X-Ray Flash 060218

abstract:
  We have studied the afterglow of the gamma-ray burst (GRB) of February 18,
2006. This is a nearby long GRB, with a very low peak energy, and is therefore
classified as an X-ray Flash (XRF). XRF 060218 is clearly associated with a
supernova -- dubbed SN 2006aj. We present early spectra for SN 2006aj as well
as optical lightcurves reaching out to 50 days past explosion. Our optical
lightcurves define the rise times, the lightcurve shapes and the absolute
magnitudes in the U, V and R bands, and we compare these data with data for
other relevant supernovae. SN 2006aj evolved quite fast, somewhat similarly to
SN 2002ap, but not as fast as SN 1994I. Our spectra show the evolution of the
supernova over the peak, when the U-band portion of the spectrum rapidly fades
due to extensive line blanketing. We compare to similar spectra of very
energetic Type Ic supernovae. Our first spectra are earlier than spectra for
any other GRB-SN. The spectrum taken 12 days after burst in the rest frame is
similar to somewhat later spectra of both SN 1998bw and SN 2003dh, implying a
rapid early evolution. This is consistent with the fast lightcurve.
  From the narrow emission lines from the host galaxy we derive a redshift of
z=0.0331+-0.0007. This makes XRF 060218 the second closest gamma-ray burst
detected. The flux of these emission lines indicate a high-excitation state,
and a modest metallicity and star formation rate of the host galaxy.


title: The shortest modulation period Blazhko RR Lyrae star: SS Cnc

abstract:
  Extended BV(RI)c CCD observations of SS Cnc, a short period RRab star are
presented. Nearly 1400 data points in each band have been obtained spanning
over 79 days during the spring of 2005. The star exhibits light curve
modulation, the so called Blazhko effect with small amplitude (B maximum
brightness varies 0.1 mag) and with the shortest modulation period (5.309 d)
ever observed. In the Fourier spectrum of the V light curve the pulsation
frequency components are detected up to the 24th harmonic order, and modulation
side lobe frequencies with significantly asymmetric amplitudes are seen up to
the 15th and 9th orders for the lower and higher frequency components,
respectively. Detailed comparison of the modulation behavior of SS Cnc and RR
Gem, the two recently discovered small amplitude, short modulation period
Blazhko stars is presented. The modulation frequency (f_m) appears in the
Fourier spectrum of both stars with similar amplitude. We also demonstrate that
the modulation frequencies have basically different properties as the pulsation
and modulation side lobe frequencies have, indicating that the physics behind
these frequency components are not the same. The discovery of small amplitude
modulations of RRab stars cautions that the large photometric surveys (MACHO,
OGLE) may seriously underestimate the number of modulated RR Lyrae stars.


title: The Dissipative Merger Progenitors of Elliptical Galaxies

abstract:
  We address the deviations of the scaling relations of elliptical galaxies
from the expectations based on the virial theorem and homology, including the
"tilt" of the "fundamental plane" and the steep decline of density with mass.
We show that such tilts result from dissipative major mergers once the gas
fraction available for dissipation declines with progenitor mass, and derive
the scaling properties of the progenitors. We use hydrodynamical simulations to
quantify the effects of major mergers with different gas fractions on the
structural properties of galaxies. The tilts are driven by the differential
shrinkage of the effective stellar radius as a function of dissipation in the
merger, while the correlated smaller enhancements in internal velocity and
stellar mass keep the slope of the velocity-stellar mass relation near V \pr
M_*^{1/4}. The progenitors match a straightforward model of disc formation in
LCDM haloes. Their total to stellar mass ratio within the effective radius
varies as M/M_* \pr M_*^-0.25, consistent with supernova feedback. They are
nearly homologous in the sense that the dark-matter fractions within the
effective and virial radii scale with mass in a similar way, with only a weak
decline of density with mass. The progenitor radius is roughly R \pr M_*^0.3,
compatible with today's intermediate late-type galaxies. This indicates that
the latest wet mergers involved relatively big discs. The dissipative gas to
stellar mass ratio is predicted to decline \pr M_*^-0.5, similar to the
observed trend in today's blue sequence galaxies. Such a trend should be
observed in relatively massive gaseous galaxies at z~1-4. The corresponding
"baryonic" relations are consistent with homology and spherical virial
equilibrium, V \pr R \pr M_b^1/3.


title: Magnetospheric Accretion in Classical T Tauri Stars

abstract:
  The inner 0.1 AU around accreting T Tauri stars hold clues to many physical
processes that characterize the early evolution of solar-type stars. The
accretion-ejection connection takes place at least in part in this compact
magnetized region around the central star, with the inner disk edge interacting
with the star's magnetosphere thus leading simultaneously to magnetically
channeled accretion flows and to high velocity winds and outflows. The magnetic
star-disk interaction is thought to have strong implications for the angular
momentum evolution of the central system, the inner structure of the disk, and
possibly for halting the migration of young planets close to the stellar
surface. We review here the current status of magnetic field measurements in T
Tauri stars, the recent modeling efforts of the magnetospheric accretion
process, including both radiative transfer and multi-D numerical simulations,
and summarize current evidence supporting the concept of magnetically-channeled
accretion in young stars. We also discuss the limits of the models and
highlight observational results which suggest that the star-disk interaction is
a highly dynamical and time variable process in young stars.


title:
A Viscous Heating Mechanism for the Hot Plasma in the Galactic Center
  Region

abstract:
  In addition to lines originating in a soft phase at ~0.8 keV and to cold
molecular clouds, the X-ray spectra from the Galactic center region also
exhibit properties similar to those of a diffuse, thin, very hot plasma at 8
keV on a scale of hundreds of parsecs. This phase is surprising for more than
one reason. First, such a hot plasma should not be bound to the Galactic plane
and the power needed to sustain the escaping matter would be higher then any
known source. Second, there is no known mechanism able to heat the plasma to
more than a few keV. Recently we have suggested that, hydrogen having escaped,
the hot plasma could be a helium plasma, heavy enough to be gravitationally
confined. In this case, the required power is much more reasonable. We present
here a possible heating mechanism which taps the gravitational energy of the
molecular clouds. We note that the 8 keV plasma is highly viscous and we show
how viscous friction of molecular clouds flowing within the hot phase can
dissipate energy in the gas and heat it. We detail the MHD wake of a spherical
cloud by considering the different MHD waves the cloud can excite. We find that
most of the energy is dissipated by the damping of Alfvenic perturbations in
two possible manners, namely by non-linear effects and by a large scale
curvature of the field lines. Depending on the field strength, this heating can
balance the radiative cooling. We note that the plasma parameters may be
optimal to make the dissipation most efficient, suggesting a self-regulation
mechanism. The loss of kinetic and gravitational energy also causes accretion
of the clouds and may have significant action on the gas dynamics in this
region between the large scale, bar dominated flow and the central accretion to
the massive black hole.


title:
Testing Cosmological General Relativity against high redshift
  observations

abstract:
  Several key relations are derived for Cosmological General Relativity which
are used in standard observational cosmology. These include the luminosity
distance, angular size, surface brightness and matter density. These relations
are used to fit type Ia supernova (SNe Ia) data, giving consistent, well
behaved fits over a broad range of redshift $0.1 < z < 2$. The best fit to the
data for the local density parameter is $\Omega_{m} = 0.0401 \pm 0.0199$.
Because $\Omega_{m}$ is within the baryonic budget there is no need for any
dark matter to account for the SNe Ia redshift luminosity data. From this local
density it is determined that the redshift where the universe expansion
transitions from deceleration to acceleration is $z_{t}= 1.095
{}^{+0.264}_{-0.155}$. Because the fitted data covers the range of the
predicted transition redshift $z_{t}$, there is no need for any dark energy to
account for the expansion rate transition. We conclude that the expansion is
now accelerating and that the transition from a closed to an open universe
occurred about $8.54 {\rm Gyr}$ ago.


title: New Results from High Energy Gamma-Ray Astronomy

abstract:
  High energy gamma-ray astronomy has recently made significant progresss
through ground-based instruments like the {\it H.E.S.S.} array of imaging
atmospheric Cherenkov telescopes. The unprecedented angular resolution and the
large field of view has allowed to spatially resolve for the first time the
morphology of gamma-ray sources in the TeV energy range. The experimental
technique is described and the types of sources detected and still expected are
discussed. Selected results include objects as different as a Galactic binary
Pulsar, the Galactic Center and Supernova Remnants but they also concern the
diffuse extragalactic optical/infrared radiation field. Finally, a scan of the
Galactic plane in TeV gamma rays is described which has led to a significant
number of new TeV sources, many of which are still unidentified in other
wavelengths. The field has a close connection with X-ray astronomy which allows
the study of the synchrotron emission from these very high energy sources.


title: Shell-type Supernova Remnants

abstract:
  The role of Supernova Remnants (SNRs) for the production of the Galactic
Cosmic Rays is reviewed from the point of view of theory and very high energy
gamma-ray experiments. The point is made that theory can describe young SNRs
very well, if the evidence from the synchrotron emission is used to empirically
determine several parameters of the theory, and thus theory can predict the
relative contributions of hadronic and leptonic gamma rays at TeV energies.
This is exemplified for several objects that have been observed intensively
during the last years. Future key observations are discussed.


title: Slow evolution of elliptical galaxies induced by dynamical friction

abstract:
  Many astrophysical problems, ranging from structure formation in cosmology to
dynamics of elliptical galaxies, refer to slow processes of evolution of
essentially collisionless self-gravitating systems. In order to determine the
relevant quasi-equilibrium configuration at time t from given initial
conditions, it is often argued that such slow evolution may be approximated in
terms of adiabatic evolution, for the calculation of which efficient
semi--analytical techniques are available. Here we focus on the slow process of
evolution, induced by dynamical friction of a host stellar system on a minority
component of "satellites", that we have investigated in a previous paper, to
determine to what extent an adiabatic description might be applied. The study
is realized by comparing directly N--body simulations of the stellar system
evolution (in two significantly different models) from initial to final
conditions in a controlled numerical environment. We demonstrate that for the
examined process the adiabatic description is going to provide incorrect
answers, not only quantitatively, but also qualitatively. The two classes of
models considered exhibit generally similar trends in evolution, with one
exception noted in relation to the evolution of the total density profile. This
simple conclusion should be taken as a warning against the indiscriminate use
of adiabatic growth prescriptions in studies of structure of galaxies.


title: Near-Infrared Photometry of Carbon Stars

abstract:
  Near-infrared, JHKL, photometry of 239 Galactic carbon-rich variable stars is
presented and discussed. From these and published data the stars were
classified as Mira or non-Mira variables and amplitudes and pulsation periods,
ranging from 222 to 948 days for the Miras, were determined for most of them. A
comparison of the colour and period relations with those of similar stars in
the Large Magellanic Cloud indicates minor differences, which may be the
consequence of sample selection effects. Apparent bolometric magnitudes were
determined by combining the mean JHKL fluxes with mid-infrared photometry from
IRAS and MSX. Then, using the Mira period luminosity relation to set the
absolute magnitudes, distances were determined -- to greater accuracy than has
hitherto been possible for this type of star. Bolometric corrections to the K
magnitude were calculated and prescriptions derived for calculating these from
various colours. Mass-loss rates were also calculated and compared to values in
the literature.
  Approximately one third of the C-rich Miras and an unknown fraction of the
non-Miras exhibit apparently random obscuration events that are reminiscent of
the phenomena exhibited by the hydrogen deficient RCB stars. The underlying
cause of this is unclear, but it may be that mass loss, and consequently dust
formation, is very easily triggered from these very extended atmospheres.


title: Carbon-Rich Mira Variables: Radial Velocities and Distances

abstract:
  Optical radial velocities have been measured for 38 C-type Mira variables.
These data together with others in the literature are used to study the
differences between optical and CO mm observations for C-Miras and the
necessary corrections to the optical velocities are derived in order to obtain
the true radial velocities of the variables. The difference between absorption
and emission line velocities is also examined. A particularly large difference
(+30 km\s) is found in the case of the H-alpha emission line. A catalogue is
given of 177 C-Miras with estimated distances and radial velocities. The
distances are based on bolometric magnitudes derived in Paper I using SAAO
observations or (for 60 of the stars) using non-SAAO photometry. In the latter
case the necessary transformations to the SAAO system are derived. These data
will be used in paper III to study the kinematics of the C-Miras.


title: Carbon-Rich Mira Variables: Kinematics and Absolute Magnitudes

abstract:
  The kinematics of galactic C-Miras are discussed on the basis of the
bolometric magnitudes and radial velocities of Papers I and II of this series.
Differential galactic rotation is used to derive a zero-point for the
bolometric period-luminosity relation which is in satisfactory agreement with
that inferred from the LMC C-Miras. We find for the galactic Miras, Mbol =
-2.54logP + 2.06 (+/- 0.24), where the slope is taken from the LMC. The mean
velocity dispersion, together with the data of Nordstroem et al. and the Padova
models, leads to a mean age for our sample of C-Miras of 1.8 +/- 0.4 Gyr and a
mean initial mass of 1.8 +/-0.2 solar masses. Evidence for a variation of
velocity dispersion with period is found, indicating a dependence of period on
age and initial mass, the longer period stars being younger. We discuss the
relation between the O- and C-Miras and also their relative numbers in
different systems.


title: Indirect signatures for axion(-like) particles

abstract:
  Magnetic field dependent transient solar observations are suggestive for
axion-photon oscillations with light axion(-like) particle involvement. Novel
dark-moon measurements with the SMART X-ray detectors can be conclusive for
radiatively decaying massive exotica like the generic solar Kaluza-Klein
axions. Furthermore, the predicted intrinsic strong solar magnetic fields could
be the reason of enhanced low energy axion production. Such an axion component
could be the as yet unknown origin of the strong quiet Sun X-ray luminosity at
energies below 1 keV. Solar axion telescopes should lower their threshold,
aiming to copy processes that might occur near the solar surface, be it due to
spontaneous or magnetically induced radiative decay of axion(-like) particles.
This is motivated also by the recent claim of an axion-like particle detection
by the laser experiment PVLAS.


title:
Past and Future of CG J1720-67.8: Constraints from Observations and
  Models

abstract:
  We discuss the evolution of the peculiar, nearby (z = 0.045), compact galaxy
group CG J1720-67.8, by interpreting a large amount of observational
information on the basis of our recent results from spectrophotometric
evolutionary synthesis models and new N-body/SPH simulations. The group, that
is composed of two spiral galaxies with a mass ratio approximately 4:1 and an
S0 galaxy in a particularly compact configuration, is undergoing an active
pre-merging phase. Several tidal features are signposts of the complex dynamics
of the system. We suggest that the observed structure of the tidal features can
be explained only if all three galaxies are involved in a strong interaction
process.


title:
Mass spectrum of primordial black holes from inflationary perturbation
  in the Randall-Sundrum braneworld: a limit on blue spectra

abstract:
  The mass spectrum of the primordial black holes formed by density
perturbation in the radiation-dominated era of the Randall-Sundrum type-2
cosmology is given. The spectrum coincides with standard four-dimensional one
on large scales but the deviation is apparent on smaller scales. The mass
spectrum is initially softer than standard four-dimensional one, while after
accretion during the earliest era it becomes harder than that. We also show
expected extragalactic diffuse photon background spectra varying the initial
perturbation power-law power spectrum and give constraints on the blue spectra
and/or the reheating temperature. The most recent observations on the small
scale density perturbation from WMAP, SDSS and Lyman-\alpha Forest are used.
What we get are interpreted as constraints on the smaller scale inflation on
the brane connected to the larger one at the scale of Lyman-\alpha Forest. If
we set the bulk curvature radius to be 0.1 mm and assume the reheating
temperature is higher than 10^6 GeV, the scalar spectral index from the smaller
scale inflation is constrained to be n \lesssim 1.3. Typically, the constraints
are tighter than standard four-dimensional one, which is also revised by us
using the most recent observations.


title: RHESSI Observation of Chromospheric Evaporation

abstract:
  We present analyses of the spatial and spectral evolution of hard X-ray
emission observed by {\it RHESSI} during the impulsive phase of an M1.7 flare
on 2003 November 13. In general, as expected, the loop top (LT) source
dominates at low energies while the footpoint (FP) sources dominate the high
energy emission. At intermediate energies, both the LT and FPs may be seen, but
during certain intervals emission from the legs of the loop dominates, in
contrast to the commonly observed LT and FP emission. The hard X-ray emission
tends to rise above the FPs and eventually merge into a single LT source. This
evolution starts first at low energies and proceeds to higher energies. The
spectrum of the resultant LT source becomes more and more dominated by a
thermal component with an increasing emission measure as the flare proceeds.
The soft and hard X-rays show a Neupert-type behavior. With a non-thermal
bremsstrahlung model the brightness profile along the loop is used to determine
the density profile and its evolution, which reveals a gradual increase of the
gas density in the loop. These results are evidence for chromospheric
evaporation and are consistent with the qualitative features of hydrodynamic
simulations of this phenomenon. However, some observed source morphology and
its evolution cannot be accounted for by previous simulations. Therefore
simulations with more realistic physical conditions are required to explain the
results and the particle acceleration and plasma heating processes.


title:
The Luminosity Function of Nearby Galaxy Clusters II: Redshifts and
  Luminosity Function for Galaxies in the Region of the Centaurus Cluster

abstract:
  We acquired spectra for a random sample of galaxies within a 0.83 square
degree region centered on the core of the Centaurus cluster. Radial velocities
were obtained for 225 galaxies to limiting magnitudes of V < 19.5. Of the
galaxies for which velocities were obtained, we find 35% to be member galaxies.
Of the 78 member galaxies, magnitudes range from 11.8 < V < 18.5 (-21.6 < M_{V}
< -14.9 for H_o = 70 km s^-1 Mpc^-1) with a limiting central surface brightness
of \mu_o < 22.5 mag arcsec^-2. We constructed the cluster galaxy luminosity
function by using these spectroscopic results to calculate the expected
fraction of cluster members in each magnitude bin. The faint-end slope of the
luminosity function using this method is shallower than the one obtained using
a statistical method to correct for background galaxy contamination. We also
use the spectroscopy results to define surface brightness criteria to establish
membership for the full sample. Using these criteria, we find a luminosity
function very similar to the one constructed with the statistical background
correction. For both, we find a faint-end slope alpha ~ -1.4. Adjusting the
surface brightness membership criteria we find that the data are consistent
with a faint-end slope as shallow as -1.22 or as steep as -1.50. We describe in
this paper some of the limitations of using these methods for constructing the
galaxy luminosity function.


title:
Magnetic fields in our Galaxy: How much do we know? III. Progress in the
  last decade

abstract:
  A decade ago, there was very limited knowledge of magnetic fields of our
Galaxy. The local fields in the Solar vicinity were known to be directed
towards a Galactic longitude $l\sim~90^{\circ}$ with reversed directions at
smaller Galacto-radii. The regular field strength was found to be about
2~$\mu$G. The filaments near the Galactic Center show the possible poloidal
fields there. There was no information about the magnetic fields in the
Galactic halo. In last decade, there has been significant progress on
measurements of the Galactic magnetic fields. In the Galactic disk, from the
RMs of a large number of newly observed pulsars, large-scale magnetic fields
along the spiral arms have been delineated in a much larger region then ever
before, with alternating directions in the arm and interarm regions. The
toroidal fields in the Galactic halo were revealed to have opposite directions
below and above the Galactic plane, which is an indication of A0 dynamo
operating in the halo. The strength of large-scale fields also has been found
from pulsar RM data to exponentially increase at smaller Galacto-radii.
Compared to the steep Kolmogorov spectrum of magnetic energy at small scales,
the large-scale magnetic fields show a shallow broken spatial magnetic energy
spectrum.


title: Evidence for a population of beamed radio intermediate quasars

abstract:
  Whether radio intermediate quasars possess relativistic jets as radio-loud
quasars is an important issue in the understanding of the origin of radio
emission in quasars. In this letter, using the two-epoch radio data obtained
during Faint Image of Radio Sky at Twenty centimeter sky (FIRST) and NOAO VLA
Sky Survey (NVSS), we identify 89 radio variable sources in the Sloan Digital
Sky Survey. Among them, more than half are radio intermediate quasars
(RL=f2cm/f2500A<250). For all objects with available multiple band radio
observations, the radio spectra are either flat or inverted. The brightness
temperature inferred from the variability is larger than the synchrotron-self
Compton limit for a stationary source in 87 objects, indicating of relativistic
beaming. Considering the sample selection and viewing angle effect, we conclude
that relativistic jets probably exist in a substantianl fraction of radio
intermediate quasars.


title:
The black hole fundamental plane from a uniform sample of radio and
  X-ray emitting broad line AGNs

abstract:
  We derived the black hole fundamental plane relationship among the 1.4GHz
radio luminosity (L_r), 0.1-2.4keV X-ray luminosity (L_X), and black hole mass
(M) from a uniform broad line SDSS AGN sample including both radio loud and
radio quiet X-ray emitting sources. We found in our sample that the fundamental
plane relation has a very weak dependence on the black hole mass, and a tight
correlation also exists between the Eddington luminosity scaled X-ray and radio
luminosities for the radio quiet subsample. Additionally, we noticed that the
radio quiet and radio loud AGNs have different power-law slopes in the
radio--X-ray non-linear relationship. The radio loud sample displays a slope of
1.39, which seems consistent with the jet dominated X-ray model. However, it
may also be partly due to the relativistic beaming effect. For radio quiet
sample the slope of the radio--X-ray relationship is about 0.85, which is
possibly consistent with the theoretical prediction from the accretion flow
dominated X-ray model. We briefly discuss the reason why our derived
relationship is different from some previous works and expect the future
spectral studies in radio and X-ray bands on individual sources in our sample
to confirm our result.


title:
Modeling the gas-phase chemistry of the transitional disk around HD
  141569A

abstract:
  Aims: The chemistry, distribution and mass of the gas in the transitional
disk around the 5 Myr old B9.5 V star HD 141569A are constrained.
  Methods: A quasi 2-dimensional (2D) chemistry code for photon dominated
regions (PDR) is used to calculate the chemistry and gas temperatures in the
disk. The calculations are performed for several gas distributions, PAH
abundances and values of the total gas mass. The resulting CO J=2-1 and J=3-2
emission lines are computed with a 2D radiative transfer code and are compared
to observations.
  Results: The CO abundance is very sensitive to the total disk mass because
the disk is in a regime where self-shielding just sets in. The observed CO
emission lines are best fit by a power-law gas distribution of 80 M_earth
starting at 80 AU from the central star, indicating that there is some gas in
the inner hole. Predictions are made for intensities of atomic fine-structure
lines. [C I], which is the dominant form of carbon in large parts of the disk,
is found to be a good alternative tracer of the gas mass.


title: Models for the Type Ic Hypernova SN 2003lw associated with GRB 031203

abstract:
  The Gamma-Ray Burst 031203 at a redshift z=0.1055 revealed a highly reddened
Type Ic Supernova, SN 2003lw, in its afterglow light. This is the third well
established case of a link between a long-duration GRB and a type Ic SN. The SN
light curve is obtained subtracting the galaxy contribution and is modelled
together with two spectra at near-maximum epochs. A red VLT grism 150I spectrum
of the SN near peak is used to extend the spectral coverage, and in particular
to constrain the uncertain reddening, the most likely value for which is
E_{G+H}(B-V) about 1.07 +/- 0.05. Accounting for reddening, SN 2003lw is about
0.3 mag brighter than the prototypical GRB-SN 1998bw. Light curve models yield
a 56Ni mass of about 0.55 solar mass. The optimal explosion model is somewhat
more massive (ejecta mass about 13 solar mass) and energetic (kinetic energy
about 6 times 10^52 erg) than the model for SN 1998bw, implying a massive
progenitor (40 - 50 solar mass). The mass at high velocity is not very large
(1.4 solar mass above 30000 km/s, but only 0.1 solar mass above 60000 km/s),
but is sufficient to cause the observed broad lines. The similarity of SNe
2003lw and 1998bw and the weakness of their related GRBs, GRB031203 and
GRB980425, suggest that both GRBs may be normal events viewed slightly off-axis
or a weaker but possibly more frequent type of GRB.


title:
Beta decay rates for nuclei with 115 < A < 140 for r-process
  nucleosynthesis

abstract:
  For r-process nucleosynthesis the beta decay rates for a number of
neutron-rich intermediate heavy nuclei are calculated. The model for the beta
strength function is able to reproduce the observed half~lives quite well.


title:
Simulating Cosmic Reionization at Large Scales II: the 21-cm Emission
  Features and Statistical Signals

abstract:
  We present detailed predictions for the redshifted 21cm signal from the epoch
of reionization. These predictions are obtained from radiative transfer
calculations on the results of large scale (100/h Mpc), high dynamic range,
cosmological simulations. We consider several scenarios for the reionization
history, of both early and extended reionization. From the simulations we
construct and analyze a range of observational characteristics, from the global
signal, via detailed images and spectra, to statistical representations of rms
fluctuations, angular power spectra, and probability distribution functions to
characterize the non-gaussianity of the 21cm signal. (abbreviated abstract)


title:
GRBs, SGRs by UHE leptons showering, blazing and re-brightening by
  precessing Gamma Jets in-off axis

abstract:
  A list of questions regarding Gamma Ray Bursts (GRBs) and Soft Gamma
Repeaters (SGRs) remain unanswered within the Fireball-cone and Magnetar
explosive scenarios. A persistent, thin (less than micron-sr solid angle)
precessing and spinning gamma jet, with a power output comparable to the
progenitor supernova (SN) or XRay pulsar, may explain these issues. The
precessing jets may have a few hours characteristic decay time, while their
decreasing intensity follow a power law for thousands of years. The orientation
of the spinning and precessing beam respect to the line of sight plays a key
role : the farthest GRB events in widest cosmic volumes correspond generally to
a very narrow and on-axis beam, while for the nearest ones sources are mostly
observable off-axis. Consequentely the far ones are the hardest and the most
bright and viceversa nearest one are mostly softer and longest ones as in Amati
correlation. We expect that nearby off-axis GRBs would be accompanied by a
chain of OT and radio bumps as in GRB030329-SN2003 and latest GRB060218-SN2006
events. Delayed blazing jets are observable in the local universe as X-Ray
Flahes (XRFs) or short GRBs often as orphan afterglow event, and at closer
distances as SGRs and anomalous X-ray Pulsars AXRPs. The gamma jet is
originated by ultra-relativistic electron pairs showering via Synchrotron (or
Inverse Compton) radiation. The electron pairs escape from the inner SN core
thanks to a more penetrating couriers, the relativistic PeV muon pairs,
themselves secondaries of inner UHE hadron jets. They are 'transparent' through
the SN shells of matter and lights; they decay far away in to electron pairs
(and later on) in gamma and neutrinos jets. Then GRBs (and SGRs) are not the
most explosive event of the Universe, but just the most beamed ones.


title: Vega is a rapidly rotating star

abstract:
  Vega, the second brightest star in the northern hemisphere, serves as a
primary spectral type standard. While its spectrum is dominated by broad
hydrogen lines, the narrower lines of the heavy elements suggested slow to
moderate rotation, giving confidence that the ground-based calibration of its
visibile spectrum could be safely extrapolated into the ultraviolet and
near-infrared (through atmosphere models), where it also serves as the primary
photometric calibrator. But there have been problems: the star is too bright
compared to its peers and it has unusually shaped absorption line profiles,
leading some to suggest that it is a distorted, rapidly rotating star seen
pole-on. Here we report optical interferometric observations of Vega which
detect the asymmetric brightness distribution of the bright, slightly offset
polar axis of a star rotating at 93% of breakup speed. In addition to
explaining the unusual brightness and line shape pecularities, this result
leads to the prediction of an excess of near-infrared emission compared to the
visible, in agreement with observations. The large temperature differences
predicted across its surface call into question composition determinations,
adding uncertainty to Vega's age and opening the possibility that its debris
disk could be substantially older than previously thought.


title: ChaMP Serendipitous Galaxy Cluster Survey

abstract:
  We present a survey of serendipitous extended X-ray sources and optical
cluster candidates from the Chandra Multi-wavelength Project (ChaMP). Our main
goal is to make an unbiased comparison of X-ray and optical cluster detection
methods. In 130 archival Chandra pointings covering 13 square degrees, we use a
wavelet decomposition technique to detect 55 extended sources, of which 6 are
nearby single galaxies. Our X-ray cluster catalog reaches a typical flux limit
of about ~10^-14 erg s^-1 cm^-2, with a median cluster core radius of 21
arcsec. For 56 of the 130 X-ray fields, we use the ChaMP's deep NOAO/4m MOSAIC
g, r, and i imaging to independently detect cluster candidates using a Voronoi
tessellation and percolation (VTP) method. Red-sequence filtering decreases the
galaxy fore/background contamination and provides photometric redshifts to
z~0.7. From the overlapping 6.1 square degree X-ray/optical imaging, we find
115 optical clusters (of which 11% are in the X-ray catalog) and 28 X-ray
clusters (of which 46% are in the optical VTP catalog). The median redshift of
the 13 X-ray/optical clusters is 0.41, and their median X-ray luminosity (0.5-2
keV) is L_X=(2.65\pm0.19)x10^43 ergs s^-1. The clusters in our sample that are
only detected in our optical data are poorer on average (~4sigma) than the
X-ray/optically matched clusters, which may partially explain the difference in
the detection fractions.


title:
Low surface brightness galaxies rotation curves in the low energy limit
  of $R^n$ gravity : no need for dark matter?

abstract:
  We investigate the possibility that the observed flatness of the rotation
curves of spiral galaxies is not an evidence for the existence of dark matter
haloes, but rather a signal of the breakdown of General Relativity. To this
aim, we consider power - law fourth order theories of gravity obtained by
replacing the scalar curvature $R$ with $f(R) = f_0 R^n$ in the gravity
Lagrangian. We show that, in the low energy limit, the gravitational potential
generated by a pointlike source may be written as $\Phi(r) \propto r^{-1} \left
[ 1 + (r/r_c)^{\beta} \right ]$ with $\beta$ a function of the slope $n$ of the
gravity Lagrangian and $r_c$ a scalelength depending on the gravitating system
properties. In order to apply the model to realistic systems, we compute the
modified potential and the rotation curve for spherically symmetric and for
thin disk mass distributions. It turns out that the potential is still
asymptotically decreasing, but the corrected rotation curve, although not flat,
is higher than the Newtonian one thus offering the possibility to fit rotation
curves without dark matter. To test the viability of the model, we consider a
sample of 15 low surface brightness (LSB) galaxies with combined HI and
H$\alpha$ measurements of the rotation curve extending in the putative dark
matter dominated region. We find a very good agreement between the theoretical
rotation curve and the data using only stellar disk and interstellar gas.


title: The dark matter halos of the bluest low surface brightness galaxies

abstract:
  We present BVI photometry and long-slit Halpha rotation curve data obtained
with ESO VLT/FORS2 for six low surface brightness galaxies with extremely blue
colours and very faint central regions. We find no evidence for a steep central
density cusp of the type predicted by many N-body simulations of cold dark
matter (CDM) halos. Our observations are instead consistent with dark matter
halos characterized by cores of roughly constant density, in agreement with
previous investigations. While unremarkable in terms of the central density
slope, these galaxies appear very challenging for existing CDM halo models in
terms of average central halo density, as measured by the Delta_(V/2)
parameter. Since most of our target galaxies are bulgeless disks, our
observations also disfavour a recently suggested mechanism for lowering the
central mass concentration of the halo by means of a fast collapse phase, as
this scenario predicts that the original CDM profile should still be detectable
in bulgeless galaxies. Other potential ways of reconciling the CDM predictions
with these observations are discussed.


title:
A search for ultra-compact dwarf galaxies in the NGC 1023 group of
  galaxies

abstract:
  We present a photometric search for UCD candidates in the nearby galaxy group
NGC 1023 (d=11 Mpc) -- the poorest environment searched for UCDs yet --, based
on wide field imaging with CFHT. After photometric and morphological selection,
we obtain a sample of 21 UCD candidates with -12<M_V<-11 mag, if located at NGC
1023's distance. From spectroscopy taken at Calar Alto observatory, we identify
the UCD candidate in closest projection to NGC 1023 as an emission line
background galaxy. Our photometric data show that in the NGC 1023 group, the
mass spectrum of analogs to Fornax/Virgo UCD is restricted to about 1/4 of the
maximum Fornax/Virgo UCD mass. More spectroscopy is needed to further constrain
the mass range of UCDs in this galaxy group.


title:
Submillimeter corrections to gravity and the metastability of white
  dwarf and neutron stars

abstract:
  The string inspired higher dimensional theories suggest modification of
Newton's law at submillimeter length scales. Inter-particle distances in white
dwarf and neutron stars are $10^{-10} cms$ and $10^{-13} cms$ respectively, and
therefore, the effects of of short distance corrections to gravity deserve
investigation. We show, by carrying out explicit analytical many-body
calculations that, in the presence of corrections, the normal state of these
compact stars become metastable. The actual quantum mechanical ground state of
the stars turns out to be unstable. However, the tunneling probability to the
unstable ground state is so small that the stars may remain trapped in the
metastable state practically for ever.


title: Bursts from the very early universe

abstract:
  Bursts of weakly interacting particles such as neutrinos or even more weakly
interacting particles such as wimps and gravitons from the very early universe
would offer a much deeper ``look back time'' to early epochs than is possible
with photons.
  We consider some of the issues related to the existence of such bursts and
their detectability. Characterizing the burst rate by a probability $\cal P$
per Hubble four-volume we find, for events in the radiation-dominated era, that
the natural unit of description is the present intensity of the CMB times $\cal
P$. The existence of such bursts would make the observation of phenomena
associated with very early times in cosmology at least conceptually possible.
One might even hope to probe the transplanckian epoch if complexes more weakly
interacting than the graviton can exist. Other conceivable applications include
the potential detectability of the formation of "pocket" universes'' in a
multiverse.


title:
Deep CFHT Photometric Survey of the Entire M33 Galaxy I: Catalogue of
  36000 Variable Point Sources

abstract:
  We have conducted a variability survey of the local group galaxy M33 using
g', r', and i' observations from 27 nights spanning 17 months made with the
MegaPrime/MegaCam instrument on the 3.6 m CFHT telescope. We identify more than
36000 variable sources with g',r',i' < 24 out of approximately 2 million point
sources in a one square degree field of view. This increases the number of
known variables in this galaxy by more than a factor of 20. In this paper we
provide a brief description of the data and a general overview of the variable
star population which includes more than 800 candidate variable blue and red
supergiant stars, more than 2000 Cepheids, and more than 19000 long period
variable AGB and RGB stars.


title:
Hubble Space Telescope Identification of the Optical Counterparts of
  Ultraluminous X-ray Sources in M51

abstract:
  We present the results of a search for optical identifications of
ultraluminous X-ray sources (ULXs) in M51 by using mosaic images taken with the
Hubble Space Telescope Advanced Camera for Surveys in filters F435W (B), F555W
(V), F814W (I), and F658N (Halpha). Our sample consisting of nine ULXs is
defined by analyzing the three Chandra observations of M51 performed in 2000
June, 2001 June, and 2003 Aug. We found four ULXs have one or two candidates
for counterparts, while two have multiple stars within their error circles. The
other three have no candidate counterparts. Four ULXs are located near or in a
star cluster, while others have no association with a cluster. These results
indicate that the companion star, environment, and origin of ULXs are probably
heterogeneous.


title: Discovery of VHE gamma-ray emission from 1ES1218+30.4

abstract:
  The MAGIC collaboration has studied the high peaked BL-Lac object
1ES1218+30.4 at a redshift z = 0.182, using the MAGIC imaging air Cherenkov
telescope located on the Canary island of La Palma. A gamma-ray signal was
observed with 6.4sigma significance. The differential energy spectrum for an
energy threshold of 120GeV can be fitted by a simple power law yielding F_E(E)
= (8.1+-2.1)*10^-7 (E/250GeV)^(-3.0+-0.4) TeV^-1 m^-2 s^-1. During the six days
of observation in January 2005 no time variability on time scales of days was
found within the statistical errors. The observed integral flux above 350GeV is
nearly a factor two below the the upper limit reported by the Whipple
Collaboration in 2003.


title: An optical supernova associated with the X-ray flash XRF 060218

abstract:
  Long-duration gamma-ray bursts (GRBs) are associated with type Ic supernovae
that are more luminous than average and that eject material at very high
velocities. Less-luminous supernovae were not hitherto known to be associated
with GRBs, and therefore GRB-supernovae were thought to be rare events. Whether
X-ray flashes - analogues of GRBs, but with lower luminosities and fewer
gamma-rays - can also be associated with supernovae, and whether they are
intrinsically 'weak' events or typical GRBs viewed off the axis of the burst,
is unclear. Here we report the optical discovery and follow-up observations of
the type Ic supernova SN 2006aj associated with X-ray flash XRF 060218.
Supernova 2006aj is intrinsically less luminous than the GRB-supernovae, but
more luminous than many supernovae not accompanied by a GRB. The ejecta
velocities derived from our spectra are intermediate between these two groups,
which is consistent with the weakness of both the GRB output and the supernova
radio flux. Our data, combined with radio and X-ray observations, suggest that
XRF 060218 is an intrinsically weak and soft event, rather than a classical GRB
observed off-axis. This extends the GRB-supernova connection to X-ray flashes
and fainter supernovae, implying a common origin. Events such as XRF 060218 are
probably more numerous than GRB-supernovae.


title: Magnetic Field Structure from Synchrotron Polarization

abstract:
  Total magnetic fields in spiral galaxies, as observed through their total
synchrotron emission, are strongest (up to \simeq 30\mu G) in the spiral arms.
The degree of radio polarization is low; the field in the arms must be mostly
turbulent or tangled. Polarized synchrotron emission shows that the resolved
regular fields are generally strongest in the interarm regions (up to \simeq
15\mu G), sometimes forming 'magnetic arms' parallel to the optical arms. The
field structure is spiral in almost every galaxy, even in flocculent and bright
irregular types which lack spiral arms. The observed large-scale patterns of
Faraday rotation in several massive spiral galaxies reveal coherent regular
fields, as predicted by dynamo models. However, in most galaxies observed so
far no simple patterns of Faraday rotation could be found. Either many dynamo
modes are superimposed and cannot be resolved by present-day telescopes, or
most of the apparently regular field is in fact anisotropic random, with
frequent reversals, due to shearing and compressing gas flows. In galaxies with
massive bars, the polarization pattern follows the gas flow. However, around
strong shocks in bars, the compression of the regular field is much lower than
that of the gas; the regular field decouples from the cold gas and is strong
enough to affect the flow of the diffuse warm gas. -- The average strength of
the total magnetic field in the Milky Way is 6\mu G near the sun and increases
to 20-40\mu G in the Galactic center region. The Galactic field is mostly
parallel to the plane, except in the center region. Rotation measure data from
pulsars indicate several field reversals, unlike external galaxies, but some
reversals could be due to distortions of the nearby field.


title: The Eclipsing ULX in NGC 3379

abstract:
  We report recent Chandra observations of the ULX in the elliptical galaxy
NGC3379 that clearly detect two flux variability cycles. Comparing these data
with the Chandra observation of ~5yr ago, we measure a flux modulation with a
period of ~12.6hr. Moreover, we find that the emission undergoes a correlated
spectral modulation, becoming softer at low flux. We argue that our results
establish this source as a ULX binary in NGC3379. Given the old stellar
population of this galaxy, the ULX is likely to be a soft transient, however
historical X-ray sampling suggests that the current on phase has lasted ~10yr.
We discuss our results in terms of ADC and wind-feedback models. We constrain
the donor mass and orbital period at the onset of mass transfer within
1.15-1.4M and 12.5-16hr, respectively. The duration of the mass-transfer phase
so far is probably ~1Gyr and the binary has been a soft X-ray transient
throughout this time. These constraints are insensitive to the mass of the
accretor.


title:
High resolution HI and radio continuum observations of the SNR
  G290.1-0.8

abstract:
  We have observed the supernova remnant (SNR) G290.1-0.8 in the 21-cm HI line
and the 20-cm radio continuum using the Australia Telescope Compact Array
(ATCA). The HI data were combined with data from the Southern Galactic Plane
Survey to recover the shortest spatial frequencies. In contrast, HI absorption
was analyzed by filtering extended HI emission, with spatial frequencies
shorter than 1.1 k-lambda. The low-resolution ATCA radio continuum image of the
remnant shows considerable internal structure, resembling a network of
filaments across its 13 arcmin diameter. A high-resolution ATCA radio continuum
image was also constructed to study the small scale structure in the SNR. It
shows that there are no structures smaller than ~17", except perhaps for a
bright knot to the south, which is probably an unrelated object. The HI
absorption study shows that the gas distribution and kinematics in front of SNR
G290.1-0.8 are complex. We estimate that the SNR probably lies in the Carina
arm, at a distance 7 (+/- 1) kpc. In addition, we have studied nearby sources
in the observed field using archival multiwavelength data to determine their
characteristics.


title: Higher order contributions to the primordial non-gaussianity

abstract:
  In this paper we calculate additional contributions to that part of the
non-Gaussianity of the curvature perturbation, which come from the three-point
correlator of the field perturbations. We estimate this contribution in the
following models for its origin: single-component inflation, multi-component
chaotic inflation, a two-component "hybrid" inflationary model, and the
curvaton scenario. In all of these models, the additional contributions to the
primordial non-gaussianity considered here, are too small to be ever detected.


title: Towards a Cosmological Hubble Diagram for Type II-P Supernovae

abstract:
  We present the first high-redshift Hubble diagram for Type II-P supernovae
(SNe II-P) based upon five events at redshift up to z~0.3. This diagram was
constructed using photometry from the Canada-France-Hawaii Telescope Supernova
Legacy Survey and absorption line spectroscopy from the Keck observatory. The
method used to measure distances to these supernovae is based on recent work by
Hamuy & Pinto (2002) and exploits a correlation between the absolute brightness
of SNe II-P and the expansion velocities derived from the minimum of the Fe II
516.9 nm P-Cygni feature observed during the plateau phases. We present three
refinements to this method which significantly improve the practicality of
measuring the distances of SNe II-P at cosmologically interesting redshifts.
These are an extinction correction measurement based on the V-I colors at day
50, a cross-correlation measurement for the expansion velocity and the ability
to extrapolate such velocities accurately over almost the entire plateau phase.
We apply this revised method to our dataset of high-redshift SNe II-P and find
that the resulting Hubble diagram has a scatter of only 0.26 magnitudes, thus
demonstrating the feasibility of measuring the expansion history, with present
facilities, using a method independent of that based upon supernovae of Type
Ia.


title: Microlensing modulation by quadrupole variation

abstract:
  We investigate microlensing in the case where the lens is considered as an
extended object. We use a multipolar expansion of the lens potential and show
that the time-varying nature of the quadrupole contribution allows to separate
it from the mass and spin contributions and leads to specific modulations of
the amplification signal. As example we study the case of binary system lenses
in our galaxy. The modulation is observable if the rotation period of the
system is smaller than the time over which the amplification is significant and
if the impact parameter of the passing light ray is sufficiently close to the
Einstein radius so that the amplification is large. Observations of this
modulation can reveal important information on the quadrupole and thus on the
gravitational radiation emitted by the binary lens. Even if not observed
directly, because of their importance the quadrupole modulation has to be
included in the error budget for high magnification ($\mu\leq7$) microlensing
events.


title:
Long gamma-ray bursts and core-collapse supernovae have different
  environments

abstract:
  When massive stars exhaust their fuel they collapse and often produce the
extraordinarily bright explosions known as core-collapse supernovae. On
occasion, this stellar collapse also powers an even more brilliant relativistic
explosion known as a long-duration gamma-ray burst. One would then expect that
long gamma-ray bursts and core-collapse supernovae should be found in similar
galactic environments. Here we show that this expectation is wrong. We find
that the long gamma-ray bursts are far more concentrated on the very brightest
regions of their host galaxies than are the core-collapse supernovae.
Furthermore, the host galaxies of the long gamma-ray bursts are significantly
fainter and more irregular than the hosts of the core-collapse supernovae.
Together these results suggest that long-duration gamma-ray bursts are
associated with the most massive stars and may be restricted to galaxies of
limited chemical evolution. Our results directly imply that long gamma-ray
bursts are relatively rare in galaxies such as our own Milky Way.


title: Testing and selection cosmological models with dark energy

abstract:
  It is described dynamics of a large class of accelerating cosmological models
in terms of dynamical systems of the Newtonian type. The evolution of the
models is reduced to the motion of a particle in a potential well parameterized
by the scale factor. This potential function can be reconstructed from distant
supernovae type Ia data and many cosmological models represented in terms of
the potential becomes in a good agreement with current observational data. It
is proposed to use the information criteria to overcome this degeneracy within
a class of A) dark energy models and B) simple models basing on modification of
the FRW equation. Two class of models can be recommended by the Akaike (AIC)
and Schwarz (BIC) information criteria: the phantom and $\Lambda$CDM models.


title: Inflation models after WMAP year three

abstract:
  The survey of models in astro-ph/0510441 is updated.For the first time, a
large fraction of the models is ruled out at more than $3\sigma$.


title:
Challenges in Detecting Gamma-Rays From Dark Matter Annihilations in the
  Galactic Center

abstract:
  Atmospheric Cerenkov Telescopes, including HESS and MAGIC, have detected a
spectrum of gamma-rays from the galactic center region which extends from
$\sim$200 GeV or lower, to at least $\sim$10 TeV. Although the source of this
radiation is not yet known, the spectrum appears to behave as a simple
power-law, which is not the expectation for gamma-rays generated through the
annihilation of dark matter particles. If instead we conclude that the source
of these gamma-rays is astrophysical in origin, this spectrum will constitute a
background for future dark matter searches using gamma-rays from this region.
In this paper we study how this background will affect the prospects for
experiments such as GLAST to detect dark matter in the galactic center. We find
that only a narrow range of dark matter annihilation rates are potentially
observable by GLAST given this newly discovered background and considering
current constraints from EGRET and HESS. We also find that a detection of line
emission, while not completely ruled out, is only possible for a very narrow
range of dark matter models and halo profiles.


title: Was Star-Formation Suppressed in High-Redshift Minihalos?

abstract:
  The primordial gas in the earliest dark matter halos, collapsing at redshifts
around z=20, with masses M_halo=10^6 M_sun, and virial temperatures
T_vir<10^4K, relied on the presence of molecules for cooling. Several
theoretical studies have suggested that gas contraction and star-formation in
these minihalos was suppressed by radiative, chemical, thermal, and dynamical
feedback processes. The recent measurement by the Wilkinson Microwave
Anisotropy Probe (WMAP) of the optical depth to electron scattering,
tau=0.09+/-0.03, provides the first empirical evidence for this suppression.
The new WMAP result is consistent with vanilla models of reionization, in which
ionizing sources populate cold dark matter (CDM) halos down to a virial
temperature of T_vir=10^4K. On the other hand, we show that in order to avoid
overproducing the optical depth, the efficiency for the production of ionizing
photons in minihalos must have been about an order of magnitude lower than
expected and lower than the efficiency in large halos that can cool via atomic
hydrogen (T_vir > 10^4K). This conclusion is insensitive to assumptions about
the efficiency of ionizing photon production in the large halos, as long as
reionization ends by z=6, as required by the spectra of bright quasars at z<6.
Our conclusion is strengthened if the clumping of the ionized gas evolves with
redshift, as suggested by semi-analytical predictions and three-dimensional
numerical simulations.


title: Using Stellar Limb-Darkening to Refine the Properties of HD 209458b

abstract:
  We use multi-band photometry to refine estimates for the planetary radius and
orbital inclination of the transiting planet system HD 209458. We gathered 1066
spectra over four distinct transits with the STIS spectrometer on the Hubble
Space Telescope using two gratings with a resolution R=1500 and a combined
wavelength range of 290-1030 nm. We divide the spectra into ten
spectrophotometric bandpasses, five for each grating, of equal wavelength span
within each grating, and fit a transit curve over all bandpasses
simultaneously. In our fit we use theoretical values for the stellar
limb-darkening to further constrain the planetary radius. We find that the
radius of HD 209458b is 1.320 +/- 0.025 R_Jup, which is a factor of two more
precise than current estimates. We also obtain improved estimates for the
orbital period P and time of center of transit T_C. Although in principle the
photon-limited precision of the STIS data should allow us to measure the timing
of individual transits to a precision of 2-7 s, we find that systematic
instrumental offsets in the measured flux from one orbit of the spacecraft to
the next degrade these measurements to a typical precision of +/- 14 s. Within
this level of error, we find no significant variations in the timing of the
eight events examined in this work.


title: On the Luminosity Dependence of the Galaxy Pairwise Velocity Dispersion

abstract:
  (Abridged) We make predictions for the pairwise velocity dispersion (PVD) of
galaxies with models that are constrained to match the projected correlation
function and luminosity function of galaxies in the Two-Degree Field Galaxy
Redshift Survey (2dFGRS). We use these data to constrain the halo occupation
distribution (HOD), then calculate the PVD by populating the halos of a high
resolution N-body simulation. We examine the luminosity and scale dependence of
the predicted PVD. At r<1 Mpc/h and r>3 Mpc/h, we find that the PVD decreases
with increasing galaxy luminosity. This result is mostly driven by the fraction
of satellite galaxies f_sat, which is well-constrained by the correlation
function. We find f_sat~25% for galaxies fainter than L_star, while for
brighter galaxies the satellite fraction rapidly declines, creating the
decrease in the PVD with luminosity. At r=1 Mpc/h, the PVD has no dependence on
luminosity because satellite galaxies dominate the statistics for all objects.
Recent measurements of the PVD in Fourier space using the "dispersion model"
have reported a strong decline in PVD with increasing luminosity at k=1 h/Mpc.
We test this method with our HOD models, finding that there is no consistent
comparison between the PVD at a given k and the true dispersion at a given
value of r. This results in a luminosity dependence in k-space that is stronger
than in configuration space. The luminosity dependence of the HOD results in
Fourier space are consistent with those measured at k=1 h/Mpc; thus the recent
measurements of the PVD are fully explainable in the context of halo occupation
models. The normalization of the PVD is lower than predicted by our fiducial
model, and reproducing it requires a lower value of Omega_m (~0.2 instead of
0.3), a lower value of sigma_8 (~0.7 instead of 0.9), or strong velocity bias.


title: Gravitational Waves from the First Stars

abstract:
  We consider the stochastic background of gravitational waves produced by an
early generation of Population III stars coupled with a normal mode of star
formation at lower redshift. The computation is performed in the framework of
hierarchical structure formation and is based on cosmic star formation
histories constrained to reproduce the observed star formation rate at redshift
$z \la 6$, the observed chemical abundances in damped Lyman alpha absorbers and
in the intergalactic medium, and to allow for an early reionization of the
Universe at $z\sim 10-20$ as indicated by the first year results released by
WMAP. We find that the normal mode of star formation produces a gravitational
wave background which peaks at 300-500 Hz and is within LIGO III sensitivity.
The Population III component peaks at lower frequencies (30-100 Hz depending on
the model), and could be detected by LIGO III as well as the planned BBO and
DECIGO interferometers.


title: Dark matter, and its darkness

abstract:
  Assuming the validity of the general relativistic description of gravitation
on astrophysical and cosmological length scales, we analytically infer that the
Friedmann-Robertson-Walker cosmology with Einsteinian cosmological constant,
and a vanishing spatial curvature constant, unambiguously requires significant
amount of dark matter. This requirement is consistent with other indications
for dark matter. The same spacetime symmetries that underlie the freely falling
frames of Einsteinian gravity also provide symmetries, which for the spin one
half representation space, furnish a novel construct that carries extremely
limited interactions with respect to the terrestrial detectors made of the
standard model material. Both the `luminous' and `dark' matter turn out to be
residents of the same representation space but they derive their respective
`luminosity' and `darkness' from either belonging to the sector with (CPT)^2 =
+ 1, or to the sector with (CPT)^2 = - 1.


title:
Modelling galaxy clustering in a high resolution simulation of structure
  formation

abstract:
  We use the Millennium Simulation, a 10 billion particle simulation of the
growth of cosmic structure, to construct a new model of galaxy clustering. We
adopt a methodology that falls midway between the traditional semi-analytic
approach and the halo occupation distribution(HOD) approach. In our model, we
adopt the positions and velocities of the galaxies that are predicted by
following the orbits and merging histories of the substructures in the
simulation. Rather than using star formation and feedback `recipes' to specify
the physical properties of the galaxies, we adopt parametrized functions to
relate these properties to the quantity M_{infall}, defined as the mass of the
halo at the epoch when the galaxy was last the central dominant object in its
own halo. We test whether these parametrized relations allow us to recover the
basic statistical properties of galaxies in the semi-analytic catalogues,
including the luminosity function, the stellar mass function and the shape and
amplitude of the two-point correlation function evaluated in different stellar
mass and luminosity ranges. We then use our model to interpret recent
measurements of these quantities from Sloan Digital Sky Survey data. We derive
relations between the luminosities and the stellar masses of galaxies in the
local Universe and their host halo masses. Our results are in excellent
agreement with recent determinations of these relations by Mandelbaum et al
using galaxy-galaxy weak lensing measurements from the SDSS.


title:
The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. III.
  Perseus Observed with IRAC

abstract:
  We present observations of 3.86 sq. deg. of the Perseus molecular cloud
complex with the Spitzer Space Telescope Infrared Array Camera (IRAC). The maps
show strong extended emission arising from shocked H2 in outflows in the region
and from polycyclic aromatic hydrocarbon features. More than 120,000 sources
are extracted toward the cloud. Based on their IRAC colors and comparison to
off-cloud and extragalactic fields, we identify 400 candidate young stellar
objects. About two thirds of these are associated with the young clusters IC348
and NGC1333, while the last third is distributed over the remaining cloud. We
classify the young stellar objects according to the traditional scheme based on
the slope of their spectral energy distributions. Significant differences are
found for the numbers of embedded Class I objects relative to more evolved
Class II objects in IC348, NGC1333 and the remaining cloud with the embedded
Class I and "flat spectrum" YSOs constituting 14%, 36% and 47% of the total
number of YSOs identified in each of these regions. The high number of Class I
objects in the extended cloud (61% of the Class I objects in the entire cloud)
suggests that a significant fraction of the current star formation is occuring
outside the two main clusters. Finally we discuss a number of outflows and
identify their driving sources, including the known deeply embedded Class 0
sources outside the two major clusters. The Class 0 objects are found to be
detected by Spitzer and have very red [3.6]-[4.5] colors but do not show
similarly red [5.8]-[8.0] colors. The Class 0 objects are easily identifiable
in color-color diagrams plotting these two colors but are problematic to
extract automatically due to the extended emission from shocked gas or
scattered light in cavities related to the associated outflows.


title:
Improved constraints on the cosmological parameters using the VLA FIRST
  survey

abstract:
  Using the final version of the VLA FIRST survey (Becker et al. 2003), the
optical Sloan Digital Sky Survey Data Release 3 (DR3) quasar list and a series
of carefully selected criteria, we have defined the largest homogeneous
population of double-lobed sources. With the precise sample definition, the
increased depth and sensitivity of the survey data, the large size of the
dataset, and our self-consistent method of analysis, which addresses many of
the problems associated with previous work in the area, we are able to: a)
explore the correlations between the intrinsic properties of the double-lobed
radio sources (the results are also confirmed by a non-parametric analysis) and
study their evolution, b) place more interesting and tighter constraints on the
cosmological parameters, distinguish among the different cosmology models, and
determine the impact of the angular size-redshift studies in cosmology, c)
further our understanding of the behavior of the intergalactic medium (IGM)
density as a function of redshift and shed more light to the quasar-radio
galaxy unification issue.


title: Linear radio structures in selected Seyfert and LINER galaxies

abstract:
  High resolution MERLIN 5 GHz observations (0.04") of 7 Seyfert galaxies,
selected as the ones previously showing evidence of collimated ejection, have
been compared with high resolution archive HST data. The radio maps reveal rich
structures in all the galaxies. NGC 2639 and TXFS 2226-184 have multiple knot
parsec-scale extended structures, Mrk 1034, Mrk 1210, NGC 4922C and NGC 5506
reveal one-sided jets, while IC 1481 exhibits a jet-like extension. The close
correlation between the radio-emitting relativistic plasma and the ionized gas
in the inner regions of these galaxies allows us to study in detail the physics
close to the center of low luminosity AGN.


title: Dwarf Galaxy Formation Was Suppressed By Cosmic Reionization

abstract:
  A large number of faint galaxies, born less than a billion years after the
big bang, have recently been discovered. The fluctuations in the distribution
of these galaxies contributed to a scatter in the ionization fraction of cosmic
hydrogen on scales of tens of Mpc, as observed along the lines of sight to the
earliest known quasars. Theoretical simulations predict that the formation of
dwarf galaxies should have been suppressed after cosmic hydrogen was reionized,
leading to a drop in the cosmic star formation rate. Here we present evidence
for this suppression. We show that the post-reionization galaxies which
produced most of the ionizing radiation at a redshift z~5.5, must have had a
mass in excess of ~10^{10.6+/-0.4} solar masses or else the aforementioned
scatter would have been smaller than observed. This limiting mass is two orders
of magnitude larger than the galaxy mass that is thought to have dominated the
reionization of cosmic hydrogen (~10^8 solar masses). We predict that future
surveys with space-based infrared telescopes will detect a population of
smaller galaxies that reionized the Universe at an earlier time, prior to the
epoch of dwarf galaxy suppression.


title: Extended Mid-Infrared Aromatic Feature Emission in M 82

abstract:
  We present new images (groundbased optical and mid-infrared (MIR) from the
Spitzer Space Telescope) and spectra (from Spitzer) of the archetypal starburst
galaxy M 82. The Spitzer data show that the MIR emission extends at least 6 kpc
along the minor axis of the galaxy. We use the optical and infrared data to
demonstrate that the extended emission is dominated by emission from dust. The
colors of the MIR emission and the spectra indicate that there is a strong
component of aromatic feature emission (the MIR features commonly attributed to
polycyclic aromatic hydrocarbons). The dust continuum and aromatic feature
emission are both strong in the well-known superwind region of this galaxy;
clearly the carrier of the aromatic features can survive in close proximity to
the wind, far from the plane of the galaxy. We also see significant emission by
dust well outside the superwind region, providing the clearest picture to date
of the dust distribution in the halo of this galaxy.


title:
The Distribution of Secondary Masses in Post-Common Envelope Binaries: A
  Potential Test of Disrupted Magnetic Braking

abstract:
  The distribution of secondary star masses in present-day post-common envelope
binaries (PCEBs) is calculated using four different models for angular momentum
loss (AML) during the post-CE phase: only gravitational radiation (GR), GR +
disrupted magnetic braking (DMB), GR + reduced MB, and GR + intermediate MB.
For the DMB model, we find that the number of PCEBs decreases abruptly by 38%
once MB begins to operate for non-fully convective secondaries. We do not find
a similar feature in the distributions calculated using any of the other three
AML models in which MB is not disrupted. This percentage decrease in the number
of present-day PCEBs predicted using the DMB model is easily large enough so
that an observed distribution of secondary masses or even spectral types in
PCEBs can provide an important test of whether magnetic braking is indeed
substantially reduced in secondary stars that are fully convective. We discuss
briefly the feasibility of such observations.


title:
From First Stars to the Spite Plateau: a Possible Reconciliation of Halo
  Stars Observations with Predictions from Big Bang Nucleosynthesis

abstract:
  Since the pioneering observations of Spite & Spite in 1982, the constant
lithium abundance of metal-poor ([Fe/H]<-1.3) halo stars near the turnoff has
been attributed a cosmological origin. Closer analysis revealed that the
observed abundance lies at $\Delta$ Li~0.4 dex below the predictions of Big
Bang Nucleosynthesis. The measurements of deuterium abundances on the lines of
sight toward quasars and the recent data from the Wilkinson Microwave
Anisotropy Probe independently confirmed this gap. We suggest here that part of
the discrepancy is explained by the first generation of stars that efficiently
depleted lithium. Assuming that the models for lithium evolution in the halo
turnoff stars and $\Delta$ Li estimates are correct, we infer that between 1/3
and 1/2 of the baryonic matter of the early halo (~10^9 Mo) was processed
through Population III stars. This new paradigm proposes a very economical
solution to the lingering difficulty of understanding the properties of the
Spite Plateau and its lack of star-to-star scatter down to [Fe/H]=-2.5. It is
moreover in agreement both with the absence of lithium detection in the most
metal-poor star presently known (HE 1327-2326), and also with new trends of the
Plateau suggesting its low metallicity edge may be reached around [Fe/H]=-2.5.
We discuss the turbulent mixing associated with enhanced supernovae explosions
in the early interstellar medium in this picture. Finally we show that other
chemical properties of the extremely metal-poor stars are in agreement with a
significant Population III processing in the halo, provided these models
include mass-loss and rotationally-induced mixing.


title: The Circumstellar Environments of Young Stars at AU Scales

abstract:
  We review recent advances in our understanding of the innermost regions of
the circumstellar environment around young stars, made possible by the
technique of long baseline interferometry at infrared wavelengths.
Near-infrared observations directly probe the location of the hottest dust. The
characteristic sizes found are much larger than previously thought, and
strongly correlate with the luminosity of the central young stars. This
relation has motivated in part a new class of models of the inner disk
structure. The first mid-infrared observations have probed disk emission over a
larger range of scales, and spectrally resolved interferometry has for the
first time revealed mineralogy gradients in the disk. These new measurements
provide crucial information on the structure and physical properties of young
circumstellar disks, as initial conditions for planet formation.


title:
European VLBI Network observations of fourteen GHz-Peaked-Spectrum radio
  sources at 5 GHz

abstract:
  We present the results of EVN polarization observations of fourteen
GHz-Peaked-Spectrum (GPS) radio sources at 5 GHz. These sources were selected
from bright GPS source samples and we aimed at finding Compact Symmetric
Objects (CSOs). We have obtained full polarization 5 GHz VLBI observations of
14 sources providing information on their source structure and spectral
indices. The results show that two core-jet sources 1433$-$040 and DA193, out
of 14 GPS sources, exhibit integrated fractional polarizations of 3.6% and 1.0%
respectively. The other 12 sources have no clear detection of pc-scale
polarization. The results confirm that the GPS sources generally have very low
polarization at 5 GHz. The sources 1133+432, 1824+271 and 2121$-$014 are
confirmed as CSOs. Three new CSOs 0914+114, 1518+046 and 2322$-$040 (tentative)
have been classified on the basis of 5 GHz images and spectral indices. The
sources 1333+589, 1751+278 and 2323+790 can be classified either as compact
doubles, and then they are likely CSO candidates or core-jet sources; further
observations are needed for an appropriate classification; 0554$-$026,
1433$-$040 and 1509+054 are core-jet sources. In addition, we estimate that a
component in the jet of quasar DA193 has superluminal motion of $3.3\pm0.6
h^{-1}c$ in 5.5 years.


title:
The Serendipitous Extragalactic X-Ray Source Identification (SEXSI)
  Program. III. Optical Spectroscopy

abstract:
  We present the catalog of 477 spectra from the Serendipitous Extragalactic
X-ray Source Identification (SEXSI) program, a survey designed to probe the
dominant contributors to the 2-10 keV cosmic X-ray background. Our survey
covers 1 deg^2 of sky to 2-10 keV fluxes of 10^-14 erg cm^-2 s^-1, and 2 deg^2
for fluxes of 3 x 10^-14 erg cm^-2 s^-1. Our spectra reach to R <24 and have
produced redshifts for 438 hard X-ray sources. The vast majority of the 2-10
keV-selected sample are AGN with redshifts between 0.1 and 3. We find that few
sources at z<1 have high X-ray luminosities, reflecting a dearth of high-mass,
high-accretion-rate sources at low redshift, a result consistent with other
recent wide-area surveys. Half of our sources show significant obscuration,
with N_H>10^22 cm^-2, independent of unobscured luminosity. We classify 168
sources as emission-line galaxies; all are X-ray luminous objects with optical
spectra lacking both high-ionization lines and evidence of a non-stellar
continuum. The redshift distribution of these emission-line galaxies peaks at a
significantly lower redshift than does that of the sources we spectroscopically
identify as AGN. We conclude that few of these sources can be powered by
starburst activity. Stacking spectra for a subset of these sources, we detect
[Ne V] emission, a clear signature of AGN activity, confirming that the
majority of these objects are Seyfert 2s in which the high-ionization lines are
diluted by stellar emission. We find 33 objects lacking broad lines in their
optical spectra which have quasar X-ray luminosities (Lx>10^44 erg s^-1), the
largest sample of such objects identified to date. In addition, we explore 17
AGN associated with galaxy clusters and find that the cluster-member AGN sample
has a lower fraction of broad-line AGN than does the background sample.


title:
Smoothing Algorithms and High-order Singularities in Gravitational
  Lensing

abstract:
  We propose a new smoothing method for obtaining surface densities from
discrete particle positions from numerical simulations. This is an essential
step for many applications in gravitational lensing. This method is based on
the ``scatter'' interpretation of the discrete density field in the Smoothed
Particle Hydrodynamics. We use Monte Carlo simulations of uniform density
fields and one isothermal ellipsoid to empirically derive the noise properties,
and best smoothing parameters (such as the number of nearest neighbors used). A
cluster from high-resolution simulations is then used to assess the reality of
high-order singularities such as swallowtails and butterflies in caustics,
which are important for the interpretation of substructures in gravitational
lenses. We also compare our method with the Delaunay tesselation field
estimator using the galaxy studied by Bradac et al. (2004), and find good
agreements. We show that higher order singularities are not only connected with
bound subhaloes but also with the satellite streams. However, the presence of
high-order singularities are sensitive to not only the fluctuation amplitude of
the surface density, but also the detailed form of the underlying smooth
lensing potential (such as ellipticity and external shear).


title: Photometric Survey of the Polar ring galaxy NGC 6822

abstract:
  We have previously established, from a carbon star survey, that the Local
Group dwarf irregular galaxy NGC 6822 is much larger than its central bright
core.
  Four MegaCam fields are acquired to survey a 2$^\circ\times$ 2$^\circ$ area
centred on NGC 6822 to fully determine its extent and map its stellar
populations. Photometry of over one million stars is obtained in the SDSS g$'$,
r$'$, i$'$ to three magnitudes below the TRGB. RGB stars, selected from their
magnitudes and colours, are used to map the NGC 6822 stellar distribution up to
a distance of 60 arcmin. We map the reddening over the whole area. We establish
that the stellar outer structure of NGC 6822 is elliptical in shape, with
$\epsilon=0.36$ and a major-axis PA = 65$^\circ$, contrasting with the
orientation of the HI disk. The density enhancement can be seen up to a
semi-major axis of 36$'$ making NGC 6822 as big as the Small Magellanic Cloud.
We fit two exponentials to the surface density profile of the spheroid, and
identify a bulge with a scale length of 3.85$'$ and an outer spheroid with a
scale length of 10.0$'$. We find intermediate-age C stars up to $\sim$ 40$'$
while demonstrating that the SDSS filters are unsuitable to identify
extragalactic C stars. NGC 6822 is a unique Local Group galaxy with shape and
structure suggesting a polar ring configuration. Radial velocities of carbon
stars have indeed demonstrated that there are two kinematical systems in NGC
6822.


title:
SINFONI Integral Field Spectroscopy of z~2 UV-selected Galaxies:
  Rotation Curves and Dynamical Evolution

abstract:
  We present 0.5" resolution near-IR integral field spectroscopy of the Ha line
emission of 14 z~2 UV-selected BM/BX galaxies obtained with SINFONI at ESO/VLT.
The mean Ha half-light radius r_1/2 is about 4kpc and line emission is detected
over > ~20kpc in several sources. In 9 sources, we detect spatially-resolved
velocity gradients, from 40 to 410 km/s over ~10kpc. The observed kinematics of
the larger systems are consistent with orbital motions. Four galaxies are well
described by rotating disks with clumpy morphologies and we extract rotation
curves out to radii > ~10kpc. One or two galaxies exhibit signatures more
consistent with mergers. Analyzing all 14 galaxies in the framework of rotating
disks, we infer mean inclination- and beam-corrected maximum circular
velocities v_c of 180+-90 km/s and dynamical masses of (0.5-25)x10^10 Msun
within r_1/2. On average, the dynamical masses are consistent with photometric
stellar masses assuming a Chabrier/Kroupa IMF but too small for a 0.1-100 Msun
Salpeter IMF. The specific angular momenta of our BM/BX galaxies are similar to
those of local late-type galaxies. The specific angular momenta of their
baryons are comparable to those of their dark matter halos. Extrapolating from
the average v_c at 10kpc, the virial mass of the typical halo of a galaxy in
our sample is 10^(11.7+-0.5) Msun. Kinematic modeling of the 3 best cases
implies a ratio of v_c to local velocity dispersion of order 2-4 and
accordingly a large geometric thickness. We argue that this suggests a mass
accretion (alternatively, gas exhaustion) timescale of ~500Myr. We also argue
that if our BM/BX galaxies were initially gas rich, their clumpy disks will
subsequently lose their angular momentum and form compact bulges on a timescale
of ~1 Gyr. [ABRIDGED]


title: Ultra-Compact H II Regions and the Early Lives of Massive Stars

abstract:
  We review the phenomenon of ultra-compact H II regions (UCHIIs) as a key
phase in the early lives of massive stars. This most visible manifestation of
massive star formation begins when the Lyman continuum output from the massive
young stellar object becomes sufficient to ionize the surroundings from which
it was born. Knowledge of this environment is gained through an understanding
of the morphologies of UCHII regions and we examine the latest developments in
deep radio and mid-IR imaging. SPITZER data from the GLIMPSE survey are an
important new resource in which PAH emission and the ionizing stars can be
seen. We review the role played by strong stellar winds from the central stars
in sweeping out central cavities and causing the limb-brightened appearance. A
range of evidence from velocity structure, proper motions, the molecular
environment and recent hydrodynamical modeling indicates that cometary UCHII
regions require a combination of champagne flow and bow shock motion. Finally,
we discuss the class of hyper-compact H II regions or broad recombination line
objects. They are likely to mark the transition soon after the breakout of the
Lyman continuum radiation from the young star. Models for these objects are
presented, including photo-evaporating disks and ionized accretion flows that
are gravitationally trapped. Evolutionary scenarios tracing young massive stars
passage through these ionized phases are discussed.