title: Kinematics of Extragalactic Radio Sources

abstract:
  Symmetric extragalactic radio sources exhibit a baffling array of features -
the remarkable symmetry between the two lobes, the emission in the radio
frequency range, well collimated jets, core regions emitting blue and
ultraviolet light, transient X-ray and gamma ray bursts, etc. In this article,
we present a model for the kinematics of extragalactic radio sources that
explains these features. We establish that an apparent superluminal motion in
both the jets of these radio sources (galactic or extragalactic) necessarily
implies real superluminal motion. The light travel time effect influences the
way we perceive superluminal motion. An object, moving across our field of
vision at superluminal speeds, will appear to us as two objects receding from a
single point. Based on this fact, we derive the kinematical properties of
extragalactic radio sources and explain the puzzling features listed above.
Furthermore, we derive the time evolution of the hot spots and compare it to
the proper motions reported in the literature. This model can also explain the
observed blue/UV spectrum (and its time evolution) of the core region and the
RF spectrum of the lobes, and why the radio sources appear to be associated
with galactic nuclei. We make other quantitative predictions, which can be
verified.


title:
3-200 keV spectral states and variability of the INTEGRAL Black Hole
  binary IGR J17464-3213

abstract:
  On March 2003, IBIS, the gamma-ray imager on board the INTEGRAL satellite,
detected an outburst from a new source, IGR J17464-3213, that turned out to be
a HEAO-1 transient, H1743-322. In this paper we report on the high energy
behaviour of this BHC studied with the three main instruments onboard INTEGRAL.
The data, collected with unprecedented sensitivity in the hard X-Ray range,
show a quite hard Comptonised emission from 3 keV up to 150 keV during the
rising part of the source outburst, with no thermal emission detectable. A few
days later, a prominent soft disk multicolour component appears, with the hard
tail luminosity almost unchanged: 10-9 erg*cm-2*s-1. Two months later, during a
second monitoring campaign near the end of the outburst, the observed disk
component was unchanged. Conversely, the Comptonised emission from the
central-hot part of the disk reduced by a factor of 10. We present here its
long term behaviour in different energy ranges and the combined JEM-X, SPI and
IBIS wide band spectral evolution of this source.


title: Warped accretion disks and the unification of Active Galactic Nuclei

abstract:
  Orientation of parsec-scale accretion disks in AGN is likely to be nearly
random for different black hole feeding episodes. Since AGN accretion disks are
unstable to self-gravity on parsec scales, star formation in these disks will
create young stellar disks, similar to those recently discovered in our
Galactic Center. The disks blend into the quasi-spherical star cluster
enveloping the AGN on time scales much longer than a likely AGN lifetime.
Therefore, the gravitational potential within the radius of the black hole
influence is at best axi-symmetric rather than spherically symmetric. Here we
show that as a result, a newly formed accretion disk will be warped. For the
simplest case of a potential resulting from a thin stellar ring, we calculate
the disk precession rates, and the time dependent shape. We find that, for a
realistic parameter range, the disk becomes strongly warped in few hundred
orbital times. We suggest that this, and possibly other mechanisms of accretion
disk warping, have a direct relevance to the problem of AGN obscuration, masing
warped accretion disks, narrow Fe K-alpha lines, etc.


title: Population synthesis in astrophysics

abstract:
  We briefly describe different astrophysical applications of a population
synthesis method. In some details we discuss the population synthesis of close
binary systems and of isolated neutron stars.


title: The role of compressibility in solar wind plasma turbulence

abstract:
  Incompressible Magnetohydrodynamics is often assumed to describe solar wind
turbulence. We use extended self similarity to reveal scaling in structure
functions of density fluctuations in the solar wind. Obtained scaling is then
compared with that found in the inertial range of quantities identified as
passive scalars in other turbulent systems. We find that these are not
coincident. This implies that either solar wind turbulence is compressible, or
that straightforward comparison of structure functions does not adequately
capture its inertial range properties.


title: Gravitational radiation from rotating monopole-string systems

abstract:
  We study the gravitational radiation from a rotating monopole-antimonopole
pair connected by a string. While at not too high frequencies the emitted
gravitational spectrum is described asymptotically by $P_n\propto n^{-1}$, the
spectrum is exponentially suppressed in the high-frequency limit, $P_n\propto
\exp(-n/n_{\rm cr})$. Below $n_{\rm cr}$, the emitted spectrum of gravitational
waves is very similar to the case of an oscillating monopole pair connected by
a string, and we argue therefore that the spectrum found holds approximately
for any moving monopole-string system. As application, we discuss the
stochastic gravitational wave background generated by monopole-antimonopole
pairs connected by strings in the early Universe and gravitational wave bursts
emitted at present by monopole-string networks. We confirm that advanced
gravitational wave detectors have the potential to detect a signal for string
tensions as small as $G\mu\sim 10^{-13}$.


title: Robustness of Cosmological Simulations I: Large Scale Structure

abstract:
  The gravitationally-driven evolution of cold dark matter dominates the
formation of structure in the Universe over a wide range of length scales.
While the longest scales can be treated by perturbation theory, a fully
quantitative understanding of nonlinear effects requires the application of
large-scale particle simulation methods. Additionally, precision predictions
for next-generation observations, such as weak gravitational lensing, can only
be obtained from numerical simulations. In this paper, we compare results from
several N-body codes using test problems and a diverse set of diagnostics,
focusing on a medium resolution regime appropriate for studying many
observationally relevant aspects of structure formation. Our conclusions are
that -- despite the use of different algorithms and error-control methodologies
-- overall, the codes yield consistent results. The agreement over a wide range
of scales for the cosmological tests is test-dependent. In the best cases, it
is at the 5% level or better, however, for other cases it can be significantly
larger than 10%. These include the halo mass function at low masses and the
mass power spectrum at small scales. While there exist explanations for most of
the discrepancies, our results point to the need for significant improvement in
N-body errors and their understanding to match the precision of near-future
observations. The simulation results, including halo catalogs, and initial
conditions used, are publicly available.


title: PSR J1756-2251: a new relativistic double neutron star system

abstract:
  We report the discovery during the Parkes Multibeam Pulsar Survey of PSR
J1756-2251, a 28.5 ms pulsar in a relativistic binary system. Subsequent timing
observations showed the pulsar to have an orbital period of 7.67 hrs and an
eccentricity of 0.18. They also revealed a significant advance of periastron,
2.585+/-0.002 deg./yr. Assuming this is entirely due to general relativity
implies a total system mass (pulsar plus companion) of 2.574+/-0.003 solar
mass. This mass and the significant orbital eccentricity suggest that this is a
double neutron star system. Measurement of the gravitational redshift, gamma,
and an evaluation of the Shapiro delay shape, s, indicate a low companion mass
of <1.25 solar mass. The expected coalescence time due to emission of
gravitational waves is only ~1.7 Gyr substantially less than a Hubble time. We
note an apparent correlation between spin period and eccentricity for normally
evolving double neutron star systems.


title: Probing Halos with PNe: Mass and Angular Momentum in Early-Type Galaxies

abstract:
  We present an observational survey program using planetary nebulae, globular
clusters, and X-ray emission to probe the halos of early-type galaxies. We
review evidence for scanty dark matter halos around ordinary elliptical
galaxies, and discuss the possible implications. We also present measurements
of rotation in the halos.


title: L- and M-band imaging observations of the Galactic Center region

abstract:
  We present near-infrared H-, K-, L- and M-band photometry of the Galactic
Center from images obtained at the ESO VLT in May and August 2002, using the
NAOS/CONICA (H and K) and the ISAAC (L and M) instruments. The large field of
view (70" x 70") of the ISAAC instrument and the large number of sources
identified (L-M data for 541 sources) allows us to investigate colors, infrared
excesses and extended dust emission. Our new L-band magnitude calibration
reveals an offset to the traditionally used calibrations, which we attribute to
the use of the variable star IRS7 as a flux calibrator. Together with new
results on the extinction towards the Galactic Center (Scoville et al. 2003;
Raab 2000), our magnitude calibration results in stellar color properties
expected from standard stars and removes any necessity to modify the K-band
extinction. The large number of sources for which we have obtained L-M colors
allows us to measure the M-band extinction to A_M=(0.056+-0.006)A_V
(approximately =A_L), a considerably higher value than what has so far been
assumed. L-M color data has not been investigated previously, due to lack of
useful M-band data. We find that this color is a useful diagnostic tool for the
preliminary identification of stellar types, since hot and cool stars show a
fairly clear L-M color separation. This is especially important if visual
colors are not available, as in the Galactic Center. For one of the most
prominent dust embedded sources, IRS3, we find extended L- and M-band continuum
emission with a characteristic bow-shock shape. An explanation for this
appearance is that IRS3 consists of a massive, hot, young mass-losing star
surrounded by an optically thick, extended dust shell, which is pushed
northwest by wind from the direction of the IRS16 cluster and SgrA*.


title:
Comparison of radiative accelerations obtained with atomic data from OP
  and OPAL

abstract:
  Here, we compare radiative accelerations (g_rad) derived from the new Opacity
Project (OP) data with those computed from OPAL and some previous data from OP.
For the case where we have full data from OPAL, the differences in the
Rosseland mean opacities between OPAL and the new OP data are within 12% and
less than 30% between new OP and previous OP data (OP1 at CDS). The radiative
accelerations g_rad differ at up to the 17% level when compared to OPAL and up
to the 38% level when compared to OP1. The comparison with OP1 on a larger
(rho-T) space gives a difference of up to 40% for g_rad(C). And it increases
for heavier elements. The differences increase for heavier elements reaching
60% for Si and 65% for S and Fe. We also constructed four representative
stellar models in order to compare the new OP accelerations with prior
published results that used OPAL data. The Rosseland means overall agree better
than 10% for all of our cases. For the accelerations, the comparisons with
published values yield larger differences in general. The published OPAL
accelerations for carbon are even larger relative to OP compare to what our
direct comparisons would indicate. Potential reasons for this puzzling behavior
are discussed. In light of the significant differences in the inferred
acceleration rates, theoretical errors should be taken into account when
comparing models with observations. The implications for stellar evolution are
briefly discussed. The sensitivity of g_rad to the atomic physics may provide a
useful test of different opacity sources.


title:
Restrictions on the Physical Prescription for the Viscosity in
  Advection-Dominated Accretion Disks

abstract:
  It has recently been demonstrated that the Shakura-Sunyaev prescription for
the kinematic viscosity in an advection-dominated accretion disk yields
physically reasonable solutions for the structure of the inflow close to the
event horizon. In particular, no violations of relativistic causality occur at
the horizon. This is somewhat surprising considering the diffusive nature of
the angular momentum transport in the Shakura-Sunyaev scenario, and it is
therefore natural to ask whether one can also obtain acceptable solutions for
the disk structure based on the various alternative models for the viscosity
that have been proposed, including the "deterministic" forms. In this paper we
perform a rigorous asymptotic analysis of the structure of an
advection-dominated accretion disk close to the event horizon of a nonrotating
black hole based on three of the alternative prescriptions for the viscosity
that have been suggested in the literature. We constrain the physical disk
model by stipulating that the stress must vanish at the horizon, which is the
fundamental inner boundary condition imposed by general relativity.
Surprisingly, we find that none of the three alternative viscosity
prescriptions yield physically acceptable disk structures close to the horizon
when the zero-torque condition is applied, whether the flow is in vertical
hydrostatic equilibrium or free-fall. Hence we conclude that the original
Shakura-Sunyaev prescription is the only one proposed so far that is physically
consistent close to the event horizon.


title:
A Self-Consistent Model for the Formation of Relativistic Outflows in
  Advection-Dominated Accretion Disks with Shocks

abstract:
  In this Letter, we suggest that the relativistic protons powering the
outflows emanating from radio-loud systems containing black holes are
accelerated at standing, centrifugally-supported shocks in hot,
advection-dominated accretion disks. Such disks are ideal sites for first-order
Fermi acceleration at shocks because the gas is tenuous, and consequently the
mean free path for particle-particle collisions generally exceeds the thickness
of the disk. The accelerated particles are therefore able to avoid
thermalization, and as a result a small fraction of them achieve very high
energies and escape from the disk. In our approach the hydrodynamics and the
particle acceleration are coupled and the solutions are obtained
self-consistently based on a rigorous mathematical treatment. The theoretical
analysis of the particle transport parallels the early studies of cosmic-ray
acceleration in supernova shock waves. We find that particle acceleration in
the vicinity of the shock can extract enough energy to power a relativistic
jet. Using physical parameters appropriate for M87 and Sgr A*, we confirm that
the jet kinetic luminosities predicted by the theory agree with the
observational estimates.


title:
Nearby early-type galaxies with ionized gas.I. Line-strength indices of
  the underlying stellar population

abstract:
  With the aim of building a data-set of spectral properties of well studied
early-type galaxies showing emission lines, we present intermediate resolution
spectra of 50 galaxies in the nearby Universe. The sample, which covers several
of the E and S0 morphological sub-classes, is biased toward objects that might
be expected to have ongoing and recent star formation, at least in small
amounts, because of the presence of the emission lines. The emission are
expected to come from the combination of active galactic nuclei and star
formation regions within the galaxies. Sample galaxies are located in
environments corresponding to a broad range of local galaxy densities, although
predominantly in low density environments. Our long-slit spectra cover the 3700
- 7250 A wavelength range with a spectral resolution of about 7.6 A at 5550 A.
The specific aim of this paper, and our first step on the investigation, is to
map the underlying galaxy stellar population by measuring, along the slit,
positioned along the galaxy major axis, line--strength indices at several,
homogeneous galacto-centric distances. For each object we extracted 7
luminosity weighted apertures corrected for the galaxy ellipticity and 4
gradients and we measured 25 line-strength indices. The paper introduces the
sample, presents the observations, describes the data reduction procedures, the
extraction of apertures and gradients, the determination and correction of the
line--strength indices, the procedure adopted to transform them into the
Lick-IDS System and the procedures adopted for the emission correction. We
finally discuss the comparisons between our dataset and line-strength indices
available in the literature.


title: Dynamical dark energy: Current constraints and forecasts

abstract:
  We consider how well the dark energy equation of state $w$ as a function of
red shift $z$ will be measured using current and anticipated experiments. We
use a procedure which takes fair account of the uncertainties in the functional
dependence of $w$ on $z$, as well as the parameter degeneracies, and avoids the
use of strong prior constraints. We apply the procedure to current data from
WMAP, SDSS, and the supernova searches, and obtain results that are consistent
with other analyses using different combinations of data sets. The effects of
systematic experimental errors and variations in the analysis technique are
discussed. Next, we use the same procedure to forecast the dark energy
constraints achieveable by the end of the decade, assuming 8 years of WMAP data
and realistic projections for ground-based measurements of supernovae and weak
lensing. We find the $2 \sigma$ constraints on the current value of $w$ to be
$\Delta w_0 (2 \sigma) = 0.20$, and on $dw/dz$ (between $z=0$ and $z=1$) to be
$\Delta w_1 (2 \sigma)=0.37$. Finally, we compare these limits to other
projections in the literature. Most show only a modest improvement; others show
a more substantial improvement, but there are serious concerns about
systematics. The remaining uncertainty still allows a significant span of
competing dark energy models. Most likely, new kinds of measurements, or
experiments more sophisticated than those currently planned, are needed to
reveal the true nature of dark energy.


title: Continuing a Chandra Survey of Quasar Radio Jets

abstract:
  We are conducting an X-ray survey of flat spectrum radio quasars (FSRQs) with
extended radio structures. We summarize our results from the first stage of our
survey, then we present findings from its continuation.
  We have discovered jet X-ray emission from 12 of our first 20 Chandra
targets, establishing that strong 0.5-7.0 keV emission is a common feature of
FSRQ jets. The X-ray morphology is varied, but in general closely matches the
radio structure until the first sharp radio bend. In the sources with optical
data as well as X-ray detections we rule out simple synchrotron models for
X-ray emission, suggesting these systems may instead be dominated by inverse
Compton (IC) scattering. Fitting models of IC scattering of cosmic microwave
background photons suggests that these jets are aligned within a few degrees of
our line of sight, with bulk Lorentz factors of a few to ten and magnetic
fields a bit stronger than $10^{-5}$ G.
  In the weeks prior to this meeting, we have discovered two new X-ray jets at
$z > 1$. One (PKS B1055+201) has a dramatic, $20''$-long jet. The other (PKS
B1421-490) appears unremarkable at radio frequencies, but at higher frequencies
the jet is uniquely powerful: its optically-dominated, with jet/core flux
ratios of 3.7 at 1 keV and 380 at 480 nm.


title: High-Energy Emission From Millisecond Pulsars

abstract:
  The X-ray and gamma-ray spectrum of rotation-powered millisecond pulsars is
investigated in a model for acceleration and pair cascades on open field lines
above the polar caps. Although these pulsars have low surface magnetic fields,
their short periods allow them to have large magnetospheric potential drops,
but the majority do not produce sufficient pairs to completely screen the
accelerating electric field. The accelerating particles maintain high Lorentz
factors and undergo cyclotron resonant absorption of radio emission, that
produces and maintains a large pitch angle, resulting in a strong synchrotron
component. The resulting spectra consist of several distinct components:
curvature radiation from primary electrons dominating from 1 - 100 GeV,
synchrotron radiation from primary and secondary electrons dominating up to
about 100 MeV, and much weaker inverse-Compton radiation from primary electrons
at 0.1 - 1 TeV. We find that the relative size of these components depends on
pulsar period, period derivative, and neutron star mass and radius with the
level of the synchrotron component also depending sensitively on the radio
emission properties. This model is successful in describing the observed X-ray
and gamma-ray spectrum of PSR J0218+4232 as synchrotron radiation, peaking
around 100 MeV and extending up to a turnover around several GeV. The predicted
curvature radiation components from a number of millisecond pulsars, as well as
the collective emission from the millisecond pulsars in globular clusters,
should be detectable with AGILE and GLAST. We also discuss a hidden population
of X-ray-quiet and radio-quiet millisecond pulsars which have evolved below the
pair death line, some of which may be detectable by telescopes sensitive above
1 GeV.


title:
The Evolution and Structure of Early-type Field Galaxies: A Combined
  Statistical Analysis of Gravitational Lenses

abstract:
  We introduce a framework for simultaneously investigating the structure and
luminosity evolution of early-type gravitational lens galaxies. The method is
based on the fundamental plane, which we interpret using the aperture
mass-radius relations derived from lensed image geometries. We apply this
method to our previous sample of 22 lens galaxies with measured redshifts and
excellent photometry. Modeling the population with a single mass profile and
evolutionary history, we find that early-type galaxies are nearly isothermal
(logarithmic density slope n = 2.06 +/- 0.17, 68% C.L.), and that their stars
evolve at a rate of dlog(M/L)_B/dz = -0.50 +/- 0.19 (68% C.L.) in the rest
frame B band. For a Salpeter IMF and a concordance cosmology, this implies a
mean star formation redshift of <z_f> > 1.5 at 95% confidence. While this model
can neatly describe the mean properties of early-type galaxies, it is clear
that the scatter of the lens sample is too large to be explained by
observational uncertainties alone. We therefore consider statistical models in
which the galaxy population is described by a distribution of star formation
redshifts. We find that stars must form over a significant range of redshifts
(Delta z_f > 1.7, 68% C.L.), which can extend as low as z_f = 1 for some
acceptable models. However, the typical galaxy will still have an old stellar
population (<z_f> > 1.5). The lens sample therefore favors early star formation
in field ellipticals -- even if we make no a priori assumption regarding the
shape of the mass distribution in lenses, and include the range of possible
deviations from homology in the uncertainties. Our evolution results call into
question several recent claims that early-type galaxies in low-density
environments have much younger stars than those in rich clusters.


title: Methanol masers in environments of three massive protostars

abstract:
  We present the first EVN maps of 6.7 GHz methanol masers of three high-mass
protostar candidates selected from the Torun unbiased survey of the Galactic
plane. A variety of linear and arc like structures was detected. A number of
maser clusters with projected sizes of 20-100 AU show monotonic velocity
gradients. Some of them are roughly perpendicular to the major axes of these
structures and can arise behind shock fronts.


title: VWhere: A Visual, Extensible `where' Command

abstract:
  In this paper we describe "VWhere," a S-Lang guilet which augments the
computational power of "where" with the point-click ease of a Gtk-based visual
interface. The result is a new mechanism for interacting with datasets, which
unifies the constraint evaluation cycle implicit within observational analysis
and provides a number of compelling advantages over traditional tool-based
methods.


title:
The DEEP Groth Strip Galaxy Redshift Survey. VIII. The Evolution of
  Luminous Field Bulges at Redshift z ~ 1

abstract:
  We present a sample of over 50 luminous field bulges (including ellipticals)
found in the Groth Strip Survey (GSS), with 0.73< z < 1.04 and with bulge
magnitudes I <= 23. The exponential disk light is removed via decomposition of
HST images using GIM2D. We find that 85% of these bulges are nearly as red as
local E/S0's and have a shallow slope and a small color dispersion in the
color-luminosity relation, suggesting roughly coeval formation. The surface
brightnesses of these bulges are about 1 mag higher than local bulges. These
results are explained adopting a "drizzling" scenario where a metal-rich early
formation is later polluted by small amounts of additional star formation.
Almost all disks have the same or bluer colors than their accompanying bulges,
regardless of the bulge-disk ratio and bulge luminosity, as expected from
semi-analytic hierarchical galaxy formation models. We present evidence that
the few blue bulge candidates are not likely to be genuine blue ellipticals or
bulges. Our deeper, more extensive, and less disk-contaminated observations
challenge prior claims that 30% to 50% of field bulges or ellipticals are in a
blue, star-forming phase at z < 1. We conclude that field bulges and
ellipticals at z ~ 1, like luminous early- type cluster galaxies at the same
redshift, are already dominated by metal-rich, old stellar populations that
have been fading from a formation epoch earlier than z ~ 1.5. (abridged)


title: Estimating Photometric Redshifts Using Support Vector Machines

abstract:
  We present a new approach to obtaining photometric redshifts using a kernel
learning technique called Support Vector Machines (SVMs). Unlike traditional
spectral energy distribution fitting, this technique requires a large and
representative training set. When one is available, however, it is likely to
produce results that are comparable to the best obtained using template fitting
and artificial neural networks. Additional photometric parameters such as
morphology, size and surface brightness can be easily incorporated. The
technique is demonstrated using samples of galaxies from the Sloan Digital Sky
Survey Data Release 2 and the hybrid galaxy formation code GalICS. The RMS
error in redshift estimation is $<0.03$ for both samples. The strengths and
limitations of the technique are assessed.


title: X-ray and Radio Monitoring of GX 339-4 and Cyg X-1

abstract:
  Previous work by Motch et al. (1985) suggested that in the low/hard state of
GX339-4, the soft X-ray power-law extrapolated backward in energy agrees with
the IR flux level. Corbel and Fender (2002) later showed that the typical hard
state radio power-law extrapolated forward in energy meets the backward
extrapolated X-ray power-law at an IR spectral break, which was explicitly
observed twice in GX339-4. This has been cited as further evidence that jet
synchrotron radiation might make a significant contribution to the observed
X-rays in the hard state. We explore this hypothesis with a series of
simultaneous radio/X-ray hard state observations of GX339-4. We fit these
spectra with a simple, but remarkably successful, doubly broken power-law model
that indeed requires a spectral break in the IR. For most of these
observations, the break position as a function of X-ray flux agrees with the
jet model predictions. We then examine the radio flux/X-ray flux correlation in
Cyg X-1 through the use of 15 GHz radio data, obtained with the Ryle radio
telescope, and Rossi X-ray Timing Explorer data, from the All Sky Monitor and
pointed observations. We find evidence of `parallel tracks' in the radio/X-ray
correlation which are associated with `failed transitions' to, or the beginning
of a transition to, the soft state. We also find that for Cyg X-1 the radio
flux is more fundamentally correlated with the hard, rather than the soft,
X-ray flux.


title:
Light Scalars and the Generation of Density Perturbations During
  Preheating or Inflaton Decay

abstract:
  Reheating after inflation can occur through inflaton decay or efficient
parametric resonant production of particles from the oscillation of the
inflaton. If the particles produced interact with scalars that were light
during inflation, then significant super-horizon density perturbations are
generated during this era. These perturbations can be highly non-Gaussian.


title: Inclusion of Binaries in Evolutionary Population Synthesis

abstract:
  Using evolutionary population synthesis we present integrated colours,
integrated spectral energy distributions and absorption-line indices defined by
the Lick Observatory image dissector scanner (referred to as Lick/IDS) system,
for an extensive set of instantaneous burst binary stellar populations with and
without binary interactions. The ages of the populations are in the range $1-15
$Gyr and the metallicities are in the range $0.0001-0.03$. By comparing the
results for populations with and without binary interactions we show that the
inclusion of binary interactions makes the integrated $\rm U-B$, $\rm B-V$,
$\rm V-R$ and $\rm R-I$ colours and all Lick/IDS spectral absorption indices
(except for $\rm H_\beta$) substantially smaller. In other words binary
evolution makes a population appear bluer. This effect raises the derived age
and metallicity of the population.
  We calculate several sets of additional solar-metallicity binary stellar
populations to explore the influence of input parameters to the binary
evolution algorithm (the common-envelope ejection efficiency and the stellar
wind mass-loss rate) on the resulting integrated colours. We also look at the
dependence on the choice of distribution functions used to generate the initial
binary population. The results show that variations in the choice of input
model parameters and distributions can significantly affect the results.
However, comparing the discrepancies that exist between the colours of various
models, we find that the differences are less than those produced between the
models with and those without binary interactions. Therefore it is very
necessary to consider binary interactions in order to draw accurate conclusions
from evolutionary population synthesis work.


title: Magnetized Turbulence

abstract:
  Several topics in the theory of magnetized turbulence are reviewed with
application to star formation and the interstellar medium. The density,
pressure, and temperature distribution in a turbulent interstellar medium is
described in comparison to a medium dominated by thermal instability. The
derivation of the empirical theory for the energy spectrum of hydrodynamic and
MHD turbulence is outlined, and comparisons are given to numerical models for
the magnetized case. Next discussed is how density fluctuations modify
observations of velocity fluctuations in line centroids, coincidentally
cancelling the effects of projection smoothing. The analytic description of
velocity structure functions as a function of the dimensionality of the
dissipative structures is then covered. Finally the question of whether
turbulence can support against gravitational collapse is addressed. Turbulence
both prevents and promotes collapse, but its net effect is to inhibit collapse,
so it does not trigger star formation in any significant sense.


title: Undulant Universe

abstract:
  If the equation of state for "dark energy" varies periodically, the expansion
of the Universe may have undergone alternating eras of acceleration and
deceleration. We examine a specific form that survives existing observational
tests, does not single out the present state of the Universe as exceptional,
and suggests a future much like the matter-dominated past: a smooth expansion
without a final inflationary epoch.


title: Gamma-Ray Bursts: Polarization of Afterglows from Two-Component Jets

abstract:
  Polarization behaviors of optical afterglows from two-component gamma-ray
burst jets are investigated, assuming various configurations for the two
components. In most cases, the observed polarization is dominated by the inner
narrow component for a long period. Interestingly, it is revealed that
different assumptions about the lateral expansion of the jet can lead to
different evolutions of the position angle of polarization. The observed
afterglow light curve and polarization behaviors of GRB 020813 can be well
explained by the two-component jet model. Particularly, the model is able to
explain the constancy of the observed position angle in this event, given that
the line of sight is slightly outside the narrow component.


title: GRB 040403: a faint X-ray rich Gamma-ray Burst discovered by INTEGRAL

abstract:
  GRB 040403 is one of the faintest gamma-ray bursts for which a rapid and
accurate localization has been obtained. Here we report on the gamma-ray
properties of this burst, based on observations with the IBIS instrument aboard
INTEGRAL, and the results of searches for its optical afterglow. The steep
spectrum (power law photon index = 1.9 in the 20-200 keV range) implies that
GRB 040403 is most likely an X-ray rich burst. Our optical limit of R > 24.2 at
16.5 hours after the burst, indicates a rather faint afterglow, similar to
those seen in other relatively soft and faint bursts.


title: Galaxy transmutations: The double ringed galaxy ESO 474-G26

abstract:
  Surface photometry and a 21cm HI line spectrum of the giant double-ringed
galaxy ESO 474-G26 are presented. The morphology of this system is unique among
the 30,000 galaxies with >B15. Two almost orthogonal optical rings with
diameters of 60 and 40 kpc surround the central body (assuming H0=70 km/s/Mpc).
The outer one is an equatorial ring, while the inner ring lies in a nearly
polar plane. The rings have blue optical colors typical of late-type spirals.
Both appear to be rotating around the central galaxy, so that this system can
be considered as a kinematically confirmed polar ring galaxy. Its observational
characteristics are typical of galaxy merger remnants. Although the central
object has a surface brightness distribution typical of elliptical galaxies, it
has a higher surface brightness for its effective radius than ordinary
ellipticals. Possible origins of this galaxy are discussed and numerical
simulations are presented that illustrate the formation of the two rings in the
merging process of two spiral galaxies, in which the observed appearance of ESO
474-G26 appears to be a transient stage.


title: Finding Faint Intermediate-mass Black Holes in the Radio Band

abstract:
  We discuss the prospects for detecting faint intermediate-mass black holes,
such as those predicted to exist in the cores of globular clusters and dwarf
spheroidal galaxies. We briefly summarize the difficulties of stellar dynamical
searches, then show that recently discovered relations between black hole mass,
X-ray luminosity and radio luminosity imply that in most cases, these black
holes should be more easily detected in the radio than in the X-rays. Finally,
we show upper limits from some radio observations of globular clusters, and
discuss the possibility that the radio source in the core of the Ursa Minor
dwarf spheroidal galaxy might be a $\sim 10,000-100,000 M_\odot$ black hole.


title:
Spallation dominated propagation of Heavy Cosmic Rays and the Local
  Interstellar Medium (LISM)

abstract:
  Measurements of ultra heavy nuclei at GeV/n energies in the galactic cosmic
radiation address the question of the sources (nucleosynthetic s- and
r-processes). As such, the determination of CR source abundances is a promising
way to discriminate between existing nucleosynthesis models. For primary
species (nuclei present and accelerated at sources), it is generally assumed
that the relative propagated abundances, if they are close in mass, are not too
different from their relative source abundances. Besides, the range of the
correction factor associated to propagation has been estimated in weighted slab
models only. Heavy CRs that are detected near Earth were accelerated from
regions that are closer to us than were the light nuclei. Hence, the geometry
of sources in the Solar neighbourhood, and as equally important, the geometry
of gas in the same region, must be taken into account. In this paper, a two
zone diffusion model is used, and as was previously investigated for
radioactive species, we report here on the impact of the local interstellar
medium (LISM) feature (under-dense medium over a scale ~100 pc) on primary and
secondary stable nuclei propagated abundances. Going down to Fe nuclei, the
connection between heavy and light abundances is also inspected. A general
trend is found that decreases the UHCR source abundances relative to the HCR
ones. This could have an impact on the level of r-process required to reproduce
the data.


title:
Metallicities on the Double Main Sequence of omega Centauri Imply Large
  Helium Enhancement

abstract:
  Having shown in a recent paper that the main sequence of omega Centauri is
split into two distinct branches, we now present spectroscopic results showing
that the bluer sequence is_less_ metal-poor. We have carefully combined
GIRAFFE@VLT spectra of 17 stars on each side of the split into a single
spectrum for each branch, with adequate S/N to show clearly that the stars of
the blue main sequence are less metal poor by 0.3 dex than those of the
dominant red one. From an analysis of the individual spectra, we could not
detect any abundance spread among the blue main sequence stars, while the red
main sequence stars show a 0.2 dex spread in metallicity. We use
stellar-structure models to show that only greatly enhanced helium can explain
the color difference between the two main sequences, and we discuss ways in
which this enhancement could have arisen.


title: The Seyfert-LINER Galaxy NGC 7213: An XMM-Newton Observation

abstract:
  We examine the XMM X-ray spectrum of the LINER-AGN NGC 7213, which is best
fit with a power law, K-alpha emission lines from Fe I, Fe XXV and Fe XXVI and
a soft X-ray collisionally ionised thermal plasma with kT=0.18 +0.03/-0.01 keV.
We find a luminosity of 7x10^(-4) L_Edd, and a lack of soft X-ray excess
emission, suggesting a truncated accretion disc. NGC 7213 has intermediate
X-ray spectral properties, between those of the weak AGN found in the LINER M81
and higher luminosity Seyfert galaxies. This supports the notion of a
continuous sequence of X-ray properties from the Galactic Centre through LINER
galaxies to Seyferts, likely determined by the amount of material available for
accretion in the central regions.


title: The Galaxy Dark Matter Connection

abstract:
  What galaxy lives in what halo? The answer to this simple question holds
important information regarding galaxy formation and evolution. We describe a
new statistical technique to link galaxies to their dark matter haloes, or
light to mass, using the clustering properties of galaxies as function of their
luminosity. The galaxy-dark matter connection thus established, and
parameterized through the conditional luminosity function, indicates the
presence of two characteristic scales in galaxy formation: one at ~10^{11}
Msun, where galaxy formation is most efficient, and another at ~10^{13} Msun,
where a transition occurs from systems dominated by one brightest, central
galaxy to systems with several dominant galaxies of comparable luminosity. We
show that the relation between light and mass established from galaxy
clustering alone is in excellent agreement with the dynamical masses inferred
from satellite kinematics. We also present a new (halo-based) galaxy-group
finder, and show that the multiplicity function of galaxy groups identified in
the 2dFGRS suggests a relatively high mass-to-light ratio on the scales of
galaxy clusters, or, alternatively, a relatively low value of sigma_8. These
findings are also supported by our studies of pairwise peculiar velocities and
satellite abundances.


title:
Probing the nature of Possible Open Cluster Remnants with the Southern
  Proper Motion Program

abstract:
  We discuss the nature of eleven Possible Open Cluster Remnants (POCRs) by
using absolute proper motions from the Southern Proper Motion (SPM) Program 3
(Girard et al. 2004) combined with near infrared photometry from 2MASS. The
analysis is done by considering the distribution of stars in the
Color-Magnitude and the Vector Point diagrams. We successfully probed the
capabilities of the SPM catalog to detect a physical group by looking at the
open cluster Blanco~1. However, within the uncertainties of the SPM3 catalog
and basing on 2MASS photometry we conclude that only one -ESO282SC26- out of
eleven objects turns out to be a probable physical group. We suggest it is an
open cluster 1.3 Gyr old and located 1.4 kpc from the Sun.


title: The density of very massive evolved galaxies to z~1.7

abstract:
  We spectroscopically identified 7 massive evolved galaxies with magnitudes
17.8<K<18.4 at 1.3<z<1.7 over an area of ~160 arcmin^2 of the MUNICS survey.
Their rest-frame K-band absolute magnitudes are -26.8<M$_K<-26.1 (5L*<L_K<10L*)
and the resulting stellar masses are in the range 3-6.5x10^{11} M_sun. The
analysis we performed unambiguously shows the early-type nature of their
spectra. The 7 massive evolved galaxies account for a comoving density of
\~5.5(+-2) x 10^{-5} Mpc^{-3} at <z>~1.5, a factor 1.5 lower than the density
(8.4(+-1) x 10^{-5} Mpc^{-3}) of early-types with comparable masses at z=0. The
incompleteness (30%) of our spectroscopic observations accounts for this
discrepancy. Thus, our data do not support a decrease of the comoving density
of early-type galaxies with masses comparable to the most massive ones in the
local Universe up to z~1.7. This suggests that massive evolved galaxies do not
play an important role in the evolution of the mass density outlined by recent
surveys in this redshift range, evolution which instead has to be ascribed to
the accretion of the stellar mass in late-type galaxies. Finally, the presence
of such massive evolved galaxies at these redshifts suggests that the assembly
of massive spheroids has taken place at z>2 supporting a high efficiency in the
accretion of the stellar mass in massive halos in the early Universe.


title:
XMM-Newton X-ray spectroscopy of the high-mass X-ray binary 4U1700-37 at
  low flux

abstract:
  We present results of a monitoring campaign of the high-mass X-ray binary
system 4U 1700-37/HD 153919, carried out with XMM-Newton in February 2001. The
system was observed at four orbital phase intervals, covering 37% of one
3.41-day orbit. The lightcurve includes strong flares, commonly observed in
this source. We focus on three epochs in which the data are not affected by
photon pile up: the eclipse, the eclipse egress and a low-flux interval in the
lightcurve around orbital phase phi ~0.25. The high-energy part of the
continuum is modelled as a direct plus a scattered component, each represented
by a power law with identical photon index (alpha ~1.4), but with different
absorption columns. We show that during the low-flux interval the continuum is
strongly reduced, probably due to a reduction of the accretion rate onto the
compact object. A soft excess is detected in all spectra, consistent with
either another continuum component originating in the outskirts of the system
or a blend of emission lines. Many fluorescence emission lines from
near-neutral species and discrete recombination lines from He- and H-like
species are detected during eclipse and egress. The detection of recombination
lines during eclipse indicates the presence of an extended ionised region
surrounding the compact object. The observed increase in strength of some
emission lines corresponding to higher values of the ionisation parameter xi
further substantiates this conclusion.


title: Initial power spectrum shape

abstract:
  Mainly used to set constraints on cosmological parameters, CMB anisotropies
can give information on primordial universe. Unfortunately, initial conditions
and late time cosmology are degenerated. I focus on the effect of the shape of
the initial power spectrum of fluctuations on the cosmological parameter
estimation from CMB temperature anisotropies. Strong constraints obtained using
a priori knowledge of the initial spectrum disappear when the latter is let
free.


title: SED models of AGN

abstract:
  Present AGN models aiming to account for the observed infrared SEDs consider
a physical description of the dust and a solution of the radiative transfer
problem. Mid infrared spectra obtained at different spatial scales are
presented. They show that PAH bands are detected in starburst regions but
significantly reduced near the centre of AGN. This may be explained by
examining the heating mechanism of PAHs after hard photon interactions. On the
radiative transfer side first a most economic model is presented where three
parameters, luminosity, effective size and extinction of the nucleus are varied
to obtain SED fits. A full grid of model spectra are made available at:
"http://www.eso.org/~rsiebenm/agn_models". This model is sufficient to account
for ISO broad band data of a sample of 68 radio galaxies and quasars of the 3CR
catalogue. The hot dust component detected is mainly due to small grains and
PAHs. In such models, type 1 AGNs are represented by a compact dust
distribution with warm grains and weak PAH emission. In AGNs of type 2, the
dust appears to be more extended, relatively colder and PAH bands are strong.
Realistic AGN models which are consistent with the unification need to explain
the overall absence of the 9.7mic. silicate emission feature. This can be done
by considering various geometries (tapered discs). Models which combine AGN and
starburst activity are presented for galaxies with hidden broad line region. It
is found that the AGN torus dominate the mid IR continuum emission and that the
starbursts dominate the PAH band as well as the far infrared and submillimeter
emission.


title: Binary Merger Progenitors for Gamma-Ray Bursts and Hypernovae

abstract:
  The collapsar model, the now leading model for the engine behind gamma-ray
bursts and hypernovae, requires that a star collapses to form a black hole
surrounded by an accretion disk of high-angular momentum material. The current
best theoretical stellar models, however, do not retain enough angular momentum
in the core of the star to make a centrifugally supported disk. In this paper,
we present the first calculations of the helium-star/helium-star merger
progenitors for the collapsar model. These progenitors invoke the merger of two
helium cores during the common envelope inspiral phase of a binary system. We
find that, in some cases, the merger can produce cores that are rotating 3-10
times faster than single stars. He-star/He-star gamma-ray burst progenitors
have a very different redshift distribution than their single-star gamma-ray
burst progenitors and we discuss how gamma-ray burst observations can constrain
these progenitors.


abstract:
  We discuss various analytical approximation methods for the evolution of the
density fluctuation in the Universe. From primordial density fluctuation, the
large-scale structure is formed via its own self-gravitational instability. For
this dynamical evolution, several approaches have been considered. In Newtonian
cosmology, in which matter motion is described by Newtonian dynamics with
cosmic expansion, Lagrangian description for the cosmic fluid is known to work
rather well for quasi-nonlinear clustering regime. In this paper, we briefly
review Lagrangian perturbation theory in Newtonian cosmology.


title:
On the X-ray emission of z~2 radio galaxies: IC scattering of the CMB &
  no evidence for fully-formed potential wells

abstract:
  We present the results of 20 ksec Chandra observations for each of 5 radio
galaxies in the redshift range 2.0 < z < 2.6. For 4 of the 5 targets we detect
unresolved X-ray components coincident with the radio nuclei. From spectral
analysis of one of the cores and comparison to the empirical radio to X-ray
luminosity ratio correlation, we find that obscuring material (n(HI)~10^22
cm^-2) may be surrounding the nuclei.
  We detect X-ray emission coincident with the radio hotspots or lobes in 4 of
the 5 targets, which can be explained by Inverse-Compton (IC) scattering of CMB
photons. The magnetic field strengths of ~100-200 muG that we derive agree with
the equipartition magnetic field strengths. The relative ease with which the
lobe X-ray emission is detected is a consequence of the (1+z)^4 increase in the
energy density of the CMB. An HST image of one of the sources shows that the
X-ray emission could also be produced by a reservoir of hot, shocked gas, as
evidenced by a bright, optical bow-shock.
  By stacking our data we created a deep, 100 ksec exposure to search for
diffuse X-ray emission from intra-cluster gas. We detect no diffuse emission
and derive upper limits of ~1e+44 erg/s, thereby ruling out a virialized
structure of cluster-size scale at z~2.
  The average number of soft X-ray sources in our fields is consistent with the
number density of AGN in the Chandra Deep Fields. Their angular distribution
shows no evidence for large-scale structure associated with the radio galaxies.


title:
Two-dimensional structure of thin transonic discs: theory and
  observational manifestations

abstract:
  We study the two-dimensional structure of thin transonic accretion discs in
the vicinity of black holes. We use the hydrodynamical version of the
Grad-Shafranov equation and focus on the region inside the marginally stable
orbit. We show that all components of the dynamical force in the disc become
significant near the sonic surface and especially important in the supersonic
region. Under certain conditions, the disc structure is shown to be far from
radial, and we review the affected disc properties, in particular the role of
the critical condition at the sonic surface: it determines neither the
accretion rate nor the angular momentum in the accretion disc. Finally, we
present a simple model explaining quasi-periodical oscillations that have been
observed in the infrared and X-ray radiation of the Galactic Centre.


title:
The Use of Transit Timing to Detect Extrasolar Planets with Masses as
  Small as Earth

abstract:
  Future surveys for transiting extrasolar planets, including the space-based
mission Kepler (Borucki et al 2003), are expected to detect hundreds of Jovian
mass planets and tens of terrestrial mass planets. For many of these newly
discovered planets, the intervals between successive transits will be measured
with an accuracy of 0.1--100 minutes. We show that these timing measurements
will allow for the detection of additional planets in the system (not
necessarily transiting), via their gravitational interaction with the
transiting planet. The transit time variations depend on the mass of the
additional planet, and in some cases Earth-mass planets will produce a
measurable effect.


title: Supernovae and Their Massive Star Progenitors

abstract:
  I briefly describe the Lick Observatory Supernova Search with the 0.76-m
Katzman Automatic Imaging Telescope. I then present an overview of optical
observations of Type II, IIb, Ib, and Ic supernovae (SNe), all of which are
thought to arise from core collapse in massive progenitors that have previously
experienced different amounts of mass loss. SNe IIn are distinguished by
relatively narrow emission lines with little or no P-Cygni absorption
component; they probably have unusually dense circumstellar gas with which the
ejecta interact. Some SNe IIn, however, might actually be super-outbursts of
luminous variable stars; rarely, they may even be SNe Ia in disguise. Plausible
detections of the progenitors of a few SNe II have been made.
Spectropolarimetry of core-collapse SNe reveals that asphericity increases
toward the core.


title:
Stellar encounters as the origin of distant solar system objects in
  highly eccentric orbits

abstract:
  The discovery of Sedna places new constraints on the origin and evolution of
our solar system. Here we investigate the possibility that a close encounter
with another star produced the observed edge of the Kuiper belt, at roughly 50
AU, and the highly elliptical orbit of Sedna. We show that a passing star
probably scattered Sedna from the Kuiper Belt into its observed orbit. The
likelihood that a planet at 60-80 AU can be scattered into Sedna's orbit is
roughly 50%; this estimate depends critically on the geometry of the flyby.
Even more interesting, though, is the roughly 10% chance that Sedna was
captured from the outer disk of the passing star. Most captures have very high
inclination orbits; detection of these objects would confirm the presence of
extrasolar planets in our own Solar System.


title:
Millimeter Wavelength Brightness Fluctuations of the Atmosphere Above
  the South Pole

abstract:
  We report measurements of the millimeter wavelength brightness fluctuations
produced by the atmosphere above the South Pole made with the Arcminute
Cosmology Bolometer Array Receiver (ACBAR). The data span the 2002 Austral
winter during which ACBAR was mounted on the Viper telescope at the South Pole.
We recover the atmospheric signal in the presence of instrument noise by
calculating the correlation between signals from distinct elements of the ACBAR
bolometer array. With this method, it is possible to measure atmospheric
brightness fluctuations with high SNR even under the most stable atmospheric
conditions. The observed atmospheric signal is characterized by the parameters
of the Komolgorov-Taylor (KT) model, which are the amplitude and power law
exponent describing the atmospheric power spectrum, and the two components of
the wind angular velocity at the time of the observation. The KT model is
typically a good description of the observed fluctuations, and fits to the data
produce values of the Komolgorov exponent that are consistent with theoretical
expectations. By combining the wind angular velocity results with measurements
of the wind linear velocity, we find that the altitude of the observed
atmospheric fluctuations is consistent with the distribution of water vapor
determined from radiosonde data. For data corresponding to frequency passbands
centered on 150, 219, and 274 GHz, we obtain median fluctuation power
amplitudes of [10, 38, 74] mK^{2} rad^{-5/3} in Rayleigh-Jeans temperature
units. Comparing with previous work, we find that these median amplitudes are
approximately an order of magnitude smaller than those found at the South Pole
during the Austral summer and at least 30 times lower than found at the ALMA
site in the Atacama desert.


title: On detecting terrestrial planets with timing of giant planet transits

abstract:
  The transits of a planet on a Keplerian orbit occur at time intervals exactly
equal to the period of the orbit. If a second planet is introduced the orbit is
not Keplerian and the transits are no longer exactly periodic. We compute the
magnitude of these variations in the timing of the transits, dt. We investigate
analytically several limiting cases: (i) interior perturbing planets with much
smaller periods; (ii) exterior perturbing planets on eccentric orbits with much
larger periods; (iii) both planets on circular orbits with arbitrary period
ratio but not in resonance; and (iv) planets on initially circular orbits
locked in resonance. Case (iv) is perhaps the most interesting case since some
systems are known to be in resonances and the perturbations are the largest. As
long as the perturber is more massive than the transiting planet, the timing
variations would be of order of the period regardless of the perturber mass!
For lighter perturbers, we show that the timing variations are smaller than the
period by the perturber to transiting planet mass ratio. An earth mass planet
in 2:1 resonance with a 3-day period transiting planet (e.g. HD 209458b) would
cause timing variations of order 3 minutes, which would be accumulated over a
year. These are easily detectable with current ground-based measurements. For
the case of both planets on eccentric orbits, we compute numerically the
transit timing variations for several cases of known multiplanet systems
assuming they were edge-on. Transit timing measurements may be used to
constrain the masses and radii of the planetary system and, when combined with
radial velocity measurements, to break the degeneracy between mass and radius
of the host star. (abstract truncated)


title: 8--13 um spectroscopy of YSOs: Evolution of the silicate feature

abstract:
  In order to investigate possible connections between dust processing and disk
properties, 8--13 um spectra of 34 young stars, with a range of circumstellar
environments and spectral types A to M, were obtained using the Long Wavelength
Spectrometer at the W. M. Keck Observatory. The broad 9.7 um amorphous silicate
feature which dominates this wavelength regime evolves from absorption in
young, embedded sources, to emission in optically revealed stars, and to
complete absence in older debris disk systems for both low- and
intermediate-mass stars. The peak wavelength and FWHM are centered about 9.7
and ~2.3 um, corresponding to amorphous olivine, with a larger spread in FWHM
for embedded sources and in peak wavelength for disks. In a few of our objects
that have been previously identified as class I low-mass YSOs, the observed
silicate feature is complex, with absorption near 9.5 um and emission peaking
around 10 um. Although most of the emission spectra show broad classical
features attributed to amorphous silicates, variations in the shape/strength
may be linked to dust processing, including grain growth and/or silicate
crystallization. We study quantitatively the evidence for evolutionary trends
in the 8--13 um spectra through a variety of spectral shape diagnostics. Based
on the lack of correlation between these diagnostics and broad-band infrared
luminosity characteristics for silicate emission sources, we conclude that
although spectral signatures of dust processing are present, they can not be
connected clearly to disk evolutionary stage (for optically thick disks) or
optical depth (for optically thin disks). The diagnostics of silicate
absorption features (other than the central wavelength of the feature),
however, are tightly correlated with optical depth.


title:
Measuring Supermassive Black Holes in Distant Galaxies with Central
  Lensed Images

abstract:
  The supermassive black hole at the center of a distant galaxy can be weighed,
in rare but realistic cases, when the galaxy acts as a strong gravitational
lens. The central image that should be produced by the lens is either destroyed
or accompanied by a second central image, depending on the mass of the black
hole. We demonstrate that when a central image pair is detected, the mass of
the black hole can be determined with an accuracy of < 0.1 dex, if the form of
the smooth mass distribution near the galaxy core is known. Uncertainty in the
central mass distribution introduces a systematic error in the black hole mass
measurement. However, even with nearly complete ignorance of the inner mass
distribution, the black hole mass can still be determined to within a factor of
10. Central image pairs should be readily observable with future radio
interferometers, allowing this technique to be used for a census of
supermassive black holes in inactive galaxies at significant redshift (0.2 < z
< 1.0).


title:
High-Resolution Measurements of the Halos of Four Dark Matter-Dominated
  Galaxies: Deviations from a Universal Density Profile

abstract:
  We derive rotation curves for four nearby, low-mass spiral galaxies and use
them to constrain the shapes of their dark matter density profiles. This
analysis is based on high-resolution two-dimensional Halpha velocity fields of
NGC 4605, NGC 5949, NGC 5963, and NGC 6689 and CO velocity fields of NGC 4605
and NGC 5963. In combination with our previous study of NGC 2976, the full
sample of five galaxies contains density profiles that span the range from
alpha_dm = 0 to alpha_dm = 1.20, where alpha_dm is the power law index
describing the central density profile. The scatter in alpha_dm from galaxy to
galaxy is 0.44, three times as large as in Cold Dark Matter (CDM) simulations,
and the mean density profile slope is alpha_dm = 0.73, shallower than that
predicted by the simulations. These results call into question the hypothesis
that all galaxies share a universal dark matter density profile. We show that
one of the galaxies in our sample, NGC 5963, has a cuspy density profile that
closely resembles those seen in CDM simulations, demonstrating that while
galaxies with the steep central density cusps predicted by CDM do exist, they
are in the minority. In spite of these differences between observations and
simulations, the relatively cuspy density profiles we find do not suggest that
this problem represents a crisis for CDM. Improving the resolution of the
simulations and incorporating additional physics may resolve the remaining
discrepancies. We also find that four of the galaxies contain detectable radial
motions in the plane of the galaxy. We investigate the hypothesis that these
motions are caused by a triaxial dark matter halo, and place lower limits on
the ellipticity of the orbits in the plane of the disk of 0.043 - 0.175.


title: An S-shaped outflow from IRAS 03256+3055 in NGC 1333

abstract:
  The IRAS source 03256+3055 in the NGC 1333 star forming region is associated
with extended sub-millimeter emission of complex morphology, showing multiple
clumps. One of these is found to coincide with the driving source of a bipolar
jet of S-shaped morphology seen in the emission lines of H_alpha and [SII] as
well as in the H2 emission lines in the K-band. Detailed images of the driving
source at the wavelengths of H_alpha and [SII] and in the I, J, H, and K bands
as well as a K-band spectrum and polarimetry are discussed. The near-infrared
morphology is characterized by a combination of line emission from the jet and
scattered light from a source with a steep continuum spectrum. The morphology
and proper motion of the jet are discussed in the context of a binary system
with a precessing disk. We conclude that the molecular core associated with
IRAS 03256+3055 consists of several clumps, only one of which shows evidence of
recent star formation at optical and near-infrared wavelengths.We also briefly
discuss a second, newly found near-infrared source associated with a compact
sub-millimeter continuum source near IRAS 03256+3055, and conclude that this
source may be physically unrelated the cluster of molecular clumps.


title:
Radio Frequency Interference Mitigation for Detection of Extended
  Sources with an Interferometer

abstract:
  Radio frequency interference (RFI) is a significant problem for current and
future radio telescopes. We describe here a method for post-correlation
cancellation of RFI for the special case of an extended source observed with an
interferometer that spatially resolves the astronomical signal. In this
circumstance, the astronomical signal is detected through the auto-correlations
of each antenna but is not present in the cross-correlations between antennas.
We assume that the RFI is detected in both auto- and cross-correlations, which
is true for many cases. The large number of cross-correlations can provide a
very high interference to noise ratio reference signal which can be adaptively
subtracted from the autocorrelation signals. The residual signal is free of
interference to significant levels. We discuss the application of this
technique for detection of the spin-flip transition of interstellar deuterium
with the Allen Telescope Array. The technique may also be of use for epoch of
reionization experiments and with multi-beam feeds on single dish telescopes.


title:
RXJ0152.7-1357: Stellar populations in an X-ray luminous galaxy cluster
  at z=0.83

abstract:
  We present a study of the stellar populations of galaxies in the cluster
RXJ0152.7-1357 at a redshift of 0.83. The study is based on new high S/N
spectroscopy of 29 cluster members covering the wavelength range 5000-10000A as
well as r'i'z' photometry of the cluster. The scaling relations between
velocity dispersions, luminosities and Balmer line strengths appear to be in
agreement with pure passive evolution of the stellar populations with a
formation redshift z=4. However, the strengths of the D4000 indices and the
metal indices do not support this interpretation. Compared to z=0, the metal
indices (C4668, Fe4383, CN3883, G4300 and CN2) show that at least half of the
non-emission line galaxies in RXJ0152.7-1357 have [alpha/Fe] of 0.2 dex higher,
and about half of the galaxies have significantly lower metal content. The
differences in stellar populations of the galaxies are associated with the
location of the galaxies relative to the X-ray emission. The galaxies with weak
C4668 and G4300, as well as galaxies with weak [OII] emission, are located in
areas of low X-ray luminosity. It is possible that these galaxies are
experiencing the effect of the cluster merger taking place in RXJ0152.7-1357 as
(short) episodes of star formation, while the galaxies in the cores of the
X-ray sub-clumps are unaffected by the merger. The spectroscopy of the
RXJ0152.7-1357 galaxies shows for the first time galaxies in a rich cluster at
intermediate redshift that cannot evolve passively into the present day galaxy
population in rich clusters. Additional physical processes may be at work and
we speculate that merging with infalling (disk) galaxies in which stars have
formed over an extended period might produce the required reduction in
[alpha/Fe]. (abridged)


title:
Chandra X-Ray Imaging of the Interacting Starburst Galaxy System NGC
  7714/5: Tidal ULXs, Emergent Wind, and Resolved HII Regions

abstract:
  We present Chandra X-ray images for the interacting galaxy pair NGC 7714/5.
In addition to the unresolved starburst nucleus, a variable point source with
L(X) ~ 10^40 erg/s was detected 1.5" (270 pc) northwest of the nucleus,
coincident with a blue, extremely optically-luminous (M(V) ~ -14.1) point
source on HST images. Eleven more candidate point-like ultraluminous X-ray
sources (ULXs) are seen, two >= 10^40 erg/s. Ten of these are associated with
interaction-induced features but only two with star formation. We found diffuse
emission with L(X) ~ 3 X 10^40 erg/s extending 11" (1.9 kpc) to the north of
the nucleus. Its spectrum can be fit with a 2-temperature Mekal function (0.6/8
keV) or a 0.6 keV Mekal function plus a power law. The hard component may be
due to high mass X-ray binaries (HMXBs) with contributions from inverse Compton
radiation, while the soft component is likely from a superwind. We also
detected extended X-ray emission from four extra-nuclear HII region complexes.
This emission may be due to HMXBs or to diffuse gas heated by winds from
supernovae, if the X-ray production efficiency L(X)/L(mech) is high (~5%). To
estimate L(X)/L(mech), we collected published data for well-studied HII regions
and superbubbles in nearby galaxies. For young HII regions (<3.5 Myrs), the
median L(X)/L(mech) ~ 0.02%, while for older regions, L(X)/L(mech) ~ 0.2-7%.
Thus gas heating by supernovae may be sufficient to account for the HII region
emission. In galaxies much more distant than NGC 7714, for example, the
Cartwheel galaxy, HII region complexes similar to those in NGC 7714 will be
unresolved by Chandra and will mimick ULXs.


title: The Centers of Early-Type Galaxies with HST. V. New WFPC2 Photometry

abstract:
  We analyze HST+WFPC2 images of 77 early-type galaxies. Brightness profiles
are classed into "core" or "power-law" forms. Cores are typically rounder than
power-law galaxies. Nearly all power-laws with central ellipticity >=0.3 have
stellar disks, implying that disks are present in power-laws with epsilon <0.3,
but are not visible due to unfavorable geometry. A few low-luminosity core
galaxies also have disks; these may be transition forms from power-laws. Cores
and power-laws both have twisting isophotes at small radii. Core galaxies have
somewhat weaker color gradients than power-laws. Nuclei are found in 29% of the
cores and 60% of the power-laws. Nuclei are typically bluer than the
surrounding galaxy. NGC 4073 and 4382 have central minima in their intrinsic
starlight distributions; NGC 4382 resembles the double nucleus of M31. In
general, the peak brightness location is coincident with the photocenter of the
core to <1 pc. Five galaxies, however, have centers significantly displaced
from their cores; these may be unresolved asymmetric double nuclei. Central
dust is visible in half of the galaxies. The presence and strength of dust
correlates with nuclear emission. The prevalence of dust and its morphology
suggests that dust clouds form, settle to the center, and disappear repeatedly
on ~10^8 yr timescales. We discuss the hypothesis that cores are created by the
decay of a massive black hole binary. Apart from their brightness profiles,
there are no strong differences between cores and power-laws that demand this
scenario; however, the rounder shapes of cores, their lack of disks, and their
reduced color gradients may be consistent with it.


title: The mass-metallicity relation at z~0.7

abstract:
  The ISM metallicity and the stellar mass are examined in a sample of 66
galaxies at 0.4<z<1, selected from the Gemini Deep Deep Survey (GDDS) and the
Canada-France Redshift Survey (CFRS). We observe a mass-metallicity relation
similar to that seen in z~0.1 SDSS galaxies, but displaced towards higher
masses and/or lower metallicities. Using this sample, and a small sample of
z~2.3 LBGs, a redshift dependent mass-metallicity relation is proposed which
describes the observed results.


title:
Forbidden Line Emission in the Eccentric Spectroscopic Binaries DQ Tauri
  and UZ Tauri E Monitored over an Orbital Period

abstract:
  We present echelle spectroscopy of the close pre-main-sequence binary star
systems DQ Tau and UZ Tau-E. Over a 16 day time interval we acquired 14 nights
of spectra for DQ Tau and 12 nights of spectra for UZ Tau-E. This represents
the entire phase of DQ Tau, and 63 percent of the phase of UZ Tau-E. As
expected, photospheric lines such as Li I 6707 clearly split into two
components as the primary and secondary orbit one another, as did the permitted
line He I 5876. Unlike the photospheric features, the forbidden lines of [O I]
6300 and [O I] 5577, retain the same shape throughout the orbit. Therefore
these lines must originate outside of the immediate vicinity of the two stars
and any circumstellar disks that participate in the orbital motion of the
stars.


title:
A Single Intrinsic Luminosity Function for Both Type-I and Type-II
  Active Galactic Nuclei

abstract:
  The luminous electromagnetic emission from distant active galactic nuclei
(AGNs) including quasars is believed to be powered by accretion onto
super-massive black holes (SMBHs). In the standard unification model for AGNs a
dusty torus covers a significant portion of the viewing angles to the accretion
disk and the BH. The system is classified as a type-I AGN if the accretion disk
is viewed through the opening part; otherwise it is called a type-II AGN.
Therefore the ratio of type-II to type-I AGNs serves as a sensitive probe to
the unification model. A surprising discovery made from several large sky
coverage and/or deep AGN surveys has found a significant anti-correlation
between the type-II fraction and the observed X-ray luminosity between 2-10
keV. This suggests two different luminosity functions for the two types of
AGNs, thus challenging the AGN unification model. However this observed
anti-correlation is a natural consequence of the AGN unification model with
only one intrinsic luminosity function if the inclination angle effects of the
X-ray emitting accretion disk are taken into account. Thus the AGN unification
model survived another critical test.


title: The B-Band Luminosity Function of Red and Blue Galaxies up to z=3.5

abstract:
  We have explored the redshift evolution of the luminosity function of red and
blue galaxies up to $z=3.5$. This was possible joining a deep I band composite
galaxy sample, which includes the spectroscopic K20 sample and the HDFs
samples, with the deep $H_{AB}=26$ and $K_{AB}=25$ samples derived from the
deep NIR images of the Hubble Deep Fields North and South, respectively. About
30% of the sample has spectroscopic redshifts and the remaining fraction
well-calibrated photometric redshifts. This allowed to select and measure
galaxies in the rest-frame blue magnitude up to $z\sim 3$ and to derive the
redshift evolution of the B-band luminosity function of galaxies separated by
their rest-frame $U-V$ color or specific (i.e. per unit mass) star-formation
rate. The class separation was derived from passive evolutionary tracks or from
their observed bimodal distributions. Both distributions appear bimodal at
least up to $z\sim 2$ and the locus of red/early galaxies is clearly identified
up to these high redshifts. Both luminosity and density evolutions are needed
to describe the cosmological behaviour of the red/early and blue/late
populations. The density evolution is greater for the early population with a
decrease by one order of magnitude at $z\sim 2-3$ with respect to the value at
$z\sim 0.4$. The luminosity densities of the early and late type galaxies with
$M_B<-20.6$ appear to have a bifurcation at $z>1$. Indeed while star-forming
galaxies slightly increase or keep constant their luminosity density, "early"
galaxies decrease in their luminosity density by a factor $\sim 5-6$ from
$z\sim 0.4$ to $z\sim 2.5-3$. A comparison with one of the latest versions of
the hierarchical CDM models shows a broad agreement with the observed number
and luminosity density evolutions of both populations.


title: Pupil Mapping in 2-D for High-Contrast Imaging

abstract:
  Pupil-mapping is a technique whereby a uniformly-illuminated input pupil,
such as from starlight, can be mapped into a non-uniformly illuminated exit
pupil, such that the image formed from this pupil will have suppressed
sidelobes, many orders of magnitude weaker than classical Airy ring
intensities. Pupil mapping is therefore a candidate technique for coronagraphic
imaging of extrasolar planets around nearby stars. The pupil mapping technique
is lossless, and preserves the full angular resolution of the collecting
telescope, so it could possibly give the highest signal-to-noise ratio of any
proposed single-telescope system for detecting extrasolar planets. A planet
fainter than $10^{-10}$ times its parent star, and as close as about $2
\lambda/D$ should be detectable. We derive the 2-dimensional equations of pupil
mapping for both 2-mirror and 2-lens systems. We give examples for both cases.
We derive analytical estimates of aberration in a 2-mirror system, and show
that the aberrations are essentially corrected with an added reversed set of
mirrors.


title: Adaptive Filters Revisited - RFI Mitigation in pulsar observations

abstract:
  Pulsar detection and timing experiments are applications where adaptive
filters seem eminently suitable tools for radio-frequency-interference (RFI)
mitigation. We describe a novel variant which works well in field trials of
pulsar observations centred on an observing frequency of 675 MHz, a bandwidth
of 64 MHz and with 2-bit sampling. Adaptive filters have generally received bad
press for RFI mitigation in radio astronomical observations with their most
serious drawback being a spectral echo of the RFI embedded in the filtered
signals. Pulsar observations are intrinsically less sensitive to this as they
operate in the (pulsar period) time domain. The field trials have allowed us to
identify those issues which limit the effectiveness of the adaptive filter. We
conclude that adaptive filters can significantly improve pulsar observations in
the presence of RFI.


title:
Development of an advanced Compton camera with gaseous TPC and
  scintillator

abstract:
  A prototype of the MeV gamma-ray imaging camera based on the full
reconstruction of the Compton process has been developed. This camera consists
of a micro-TPC that is a gaseous Time Projection Chamber (TPC) and
scintillation cameras. With the information of the recoil electrons and the
scattered gamma-rays, this camera detects the energy and incident direction of
each incident gamma-ray. We developed a prototype of the MeV gamma-ray camera
with a micro-TPC and a NaI(Tl) scintillator, and succeeded in reconstructing
the gamma-rays from 0.3 MeV to 1.3 MeV. Measured angular resolutions of ARM
(Angular Resolution Measure) and SPD (Scatter Plane Deviation) for 356 keV
gamma-rays were $18^\circ$ and $35^\circ$, respectively.


title: QSSC re-examined for the newly discovered SNe Ia

abstract:
  We examine the possible consistency of the quasi-steady state model with the
newly discovered SNe Ia. The model assumes the existence of metallic dust
ejected from the SNe explosions, which extinguishes light travelling over long
distances. We find that the model shows a reasonable fit to the data, which
improves if one takes account of the weak gravitational lensing effect of the
SNe which have been observed on the brighter side.


title: Where are the stars?

abstract:
  The 2dFGRS is used in conjunction with the 2MASSXSC to study the near-IR
light and stellar mass content of the local Universe. Mock galaxy catalogues,
constructed from cosmological N-body simulations and semi-analytical galaxy
formation models, are used to gauge the accuracy with which quantities can be
recovered. The mean luminosity densities of the Universe are found to be
rho_J=(3.57+/-0.11)*10^8 h Lsol/Mpc^3 and rho_KS=(7.04+/-0.23)*10^8 h
Lsol/Mpc^3 (statistical uncertainty). Using the 2PIGG catalogue, the group
dynamical mass-to-light ratio in the K_S band is found to increase by a factor
of ~3 when going from groups with total bJ-band luminosities of 3*10^10 h^-2
Lsol to rich clusters, which have typical values of Upsilon_K~80 h Upsilon_sol.
Taking into account the bias introduced by uncertainties in estimating galaxy
stellar masses from luminosities, a value of Omega_* h=(0.99+/-0.03)*10^-3 is
measured, assuming that a Kennicutt stellar IMF is applicable to all galaxies.
The 2PIGGs are then used to study the distribution of the stellar content of
the local Universe. The three main conclusions are: (1) a slowly rising stellar
M/L_KS is found with the clusters having the largest value of ~0.6 Upsilon_sol,
(2) in contrast, the fraction of mass in stars decreases with increasing group
size, reaching ~5*10^-3 h for the rich clusters, and (3) in answer to the
question posed in the title, most stellar mass is contained in Local
Group-sized objects (M~2*10^12 h^-1 Msol) with only ~2% in clusters with
M>5*10^14 h^-1 Msol.


title: The Rest-frame Optical Spectra of SCUBA Galaxies

abstract:
  We present near-infrared spectroscopy and narrow-band imaging at the
wavelength of redshifted H-alpha for a sample of 30 high-redshift, far-infrared
luminous galaxies. This sample is selected from surveys in the sub-millimeter,
millimeter and radio wavebands and has complete redshift coverage with a median
redshift of z~2.4. Removing obvious AGN, we find that the predicted H-alpha
star formation rates in this diverse population are suppressed (by ~10x)
compared to those derived from their far-infrared luminosities. We estimate
that AGN are present in at least 40% of the galaxies in our sample. To further
investigate this, we construct a composite rest-frame spectrum for both the
entire sample and for those galaxies which individually show no signs of
nuclear activity. We find [NII]/H-alpha ratios for both composite spectra which
suggest that the energy output of the galaxies is star-formation- rather than
AGN-dominated. The median H-alpha line width for our sample (removing obvious
AGN) is 400+/-70km/s (FWHM), and the typical spatial extent of the H-alpha
emission in our narrow-band observations is < 4-8kpc, which indicates a
dynamical mass of 1-2 x 10^11 Mo. This estimate is larger than recent estimates
of the dynamical masses of UV-selected galaxies at similar redshifts derived in
an identical manner. We also compared our H-alpha and far-infrared luminosities
with deep Chandra observations of a subset of our survey fields and use these
data to further assess their AGN content. We conclude that these high-redshift,
far-infrared luminous galaxies represent a population of massive, metal-rich,
merging systems with high instantaneous star formation rates, strong dust
obscuration and actively-fueled AGN which are likely to be the progenitors of
massive local elliptical galaxies. (abridged)


title: Evidence for extended, obscured starbursts in submm galaxies

abstract:
  We compare high-resolution optical and radio imaging of 12 luminous submm
galaxies at z=2.2+/-0.2 observed with HST and the MERLIN and VLA at comparable
spatial resolution, 0.3" (2kpc). The radio emission traces the likely
far-infrared morphology of these dusty, luminous galaxies. In ~30% of the
sample the radio appears unresolved, suggesting that the emission is compact:
either an obscured AGN or nuclear starburst. However, in the majority, ~70%
(8/12), the radio emission is resolved by MERLIN/VLA on scales of ~1" (10 kpc).
For these galaxies the radio morphologies are broadly similar to their
restframe UV emission seen by HST. We discuss the probable mechanisms for the
extended emission and conclude that their luminous radio and submm emission
arises from a large, spatially-extended starburst. The median SFRs are
1700Mo/yr occuring within a ~40kpc^2 region, giving a star formation density of
45Mo/yr/kpc^2. Such vigorous and extended starbursts appear to be uniquely
associated with the submm population. A more detailed comparison of the
distribution of UV and radio emission shows that the broad similarities on
large scales are not carried through to smaller scales, where there is rarely a
one-to-one correspondance. We interpret this as resulting from highly
structured internal obscuration, suggesting that the vigorous activity is
producing wind-blown channels through the obscuration in these galaxies. If
correct this underlines the difficulty of using UV morphologies to understand
structural properties of this population and also may explain the surprising
frequency of Ly-alpha emission in their spectra. [Abridged]


title: Structure formation constraints on the Jordan-Brans-Dicke theory

abstract:
  We use cosmic microwave background data from WMAP, ACBAR, VSA and CBI, and
galaxy power spectrum data from 2dF, to constrain flat cosmologies based on the
Jordan-Brans-Dicke theory, using a Markov Chain Monte Carlo approach. Using a
parametrization based on \xi=1/4\omega, and performing an exploration in the
range \ln\xi \in [-9,3], we obtain a 95% marginalized probability bound of
\ln\xi < -6.2, corresponding to a 95% marginalized probability lower bound on
the Brans-Dicke parameter \omega>120.


title: High-mass star formation in the Southern Hemisphere sky

abstract:
  We report on a multi-wavelength (IR to cm) and multi-resolution (1 mas to 20
arcsec) exploration of high-mass star formation regions in the Galactic plane,
at longitudes observable from the Southern Hemisphere. Our source sample was
originally identified through methanol masers in the Galactic plane, which
exclusively trace high-mass star-forming regions. (Sub)millimetre continuum and
molecular line observations were carried out with SEST/SIMBA, JCMT/SCUBA and
ATNF/Mopra mm-wave telescopes and have allowed us to identify massive ($>20$
M$_{\odot}$) and luminous ($>10^3$ L$_{\odot}$) clumps in each star-forming
region. We have also constrained the SED with additional archival IR data, the
physical conditions ($T_{dust}$, $L$, $M$) and the chemical composition of each
massive clump. Several types of objects were characterised based on the
$L_{submm}/L_{bol}$ ratio, the dust temperature and the molecular line
properties, ranging from class 0-like YSO clusters ($L_{sub}/L_{bol}\sim1%$,
T=30 K) to hot molecular clumps ($L_{sub}/L_{bol}\sim0.1%$, $T=40-200$ K).
Preliminary high-angular resolution observations for a subset of the sample
with the ATNF/ATCA at 3 mm, the VLA at 15, 22 and 43 GHz and Gemini in MIR have
revealed that several (proto)stellar objects are embedded in the massive
clumps: massive protostars, hot cores and hyper-compact HII regions. We have
thus identified protoclusters of massive YSOs, which are the precursors of the
OB associations. This sample of Southern Hemisphere star-forming regions will
be extremely valuable for the scientific preparation of the ALMA and HSO
observations.


title: The Nature of Dark Energy from deep Cluster Abundance

abstract:
  We show that using the redshift dependence of the deep cluster abundance to
detect the nature of Dark Energy is a serious challenge. We compare the
expected differences between flat LCDM models, with different Omega_mo, with
the difference between LCDM and dynamical DE models. In the former case,
cluster abundances in comoving volume and geometrical factors act in the same
direction, yielding a significant difference between the expected angular
densities. On the contrary, when we keep a constant Omega_mo and change the DE
nature,abundances in comoving volume and geometrical factors act in the
opposite direction, so that the expected differences in angular densities
reduce to small factors.


title:
A Study of Edge-On Galaxies with the Hubble Space Telescope's Advanced
  Camera for Surveys. I. Initial Results

abstract:
  We present the initial results of a Hubble Space Telescope/ACS snapshot
survey of 16 nearby, edge-on, late-type galaxies covering a range in distance
from 2 to 19 Mpc. The images of these galaxies show significant resolved
stellar populations. We derive F606W and F814W photometry for >1.2 million
stars, and present color-magnitude diagrams which show a mixture of young,
intermediate, and old stars in each galaxy. In one of the fields we
serendipitously detect stars from the Large Magellanic Cloud. We also identify
a candidate young dwarf galaxy lying ~2 kpc above the plane of NGC 4631. For
the nearest six galaxies, we derive tip of the red giant branch distances and
demonstrate that these galaxies fall on the K-band Tully-Fisher relation
established in clusters. From the color of the red giant branch, we also find
evidence that these galaxies possess a metal-poor thick disk or halo
population.


title: VLBA imaging of a periodic 12.2 GHz methanol maser flare in G9.62+0.20E

abstract:
  The class II methanol maser source G9.62+0.20E undergoes periodic flares at
both 6.7 and 12.2 GHz. The flare starting in 2001 October was observed at seven
epochs over three months using the VLBA at 12.2 GHz. High angular resolution
images (beam size $\sim$ 1.7 x 0.6 mas) were obtained, enabling us to observe
changes in 16 individual maser components. It was found that while existing
maser spots increased in flux density, no new spots developed and no changes in
morphology were observed. This rules out any mechanism which disturbs the
masing region itself, implying that the flares are caused by a change in either
the seed or pump photon levels. A time delay of 1--2 weeks was observed between
groups of maser features. These delays can be explained by light travel time
between maser groups. The regularity of the flares can possibly be explained by
a binary system.


title: AGNs and microquasars as high energy gamma-ray sources

abstract:
  The extragalactic analogs of the microquasars, the quasars, are strong
gamma-ray emitters at GeV energies. It is expected that microquasars are also
gamma-ray sources, because of the analogy with quasars and because theoretical
models predict the high-energy emission. There are two microquasars that appear
as the possible counterparts for two unidentified high-energy gamma-ray
sources.


title: Helium line formation and abundance in a solar active region

abstract:
  An observing campaign (SOHO JOP 139), coordinated between ground based and
SOHO instruments, has been planned to obtain simultaneous spectroheliograms of
the same active region in several spectral lines. The chromospheric lines CaII
K, Halpha and Na D as well as HeI 10830, 5876, 584 and HeII 304 AA lines have
been observed.These simultaneous observations allow us to build semi-empirical
models of the chromosphere and low transition region of an active region,
taking into account the estimated total number of photoionizing photons
impinging on the target active region and their spectral distribution. We
obtained a model that matches very well all the observed line profiles, using a
standard value for the He abundance ([He]=0.1) and a modified distribution of
microturbulence. For this model we study the influence of the coronal radiation
on the computed helium lines. We find that, even in an active region, the
incident coronal radiation has a limited effect on the UV He lines, while it
results of fundamental importance for the 5876 and 10830 lines. Finally we
build two more models assuming values of He abundance [He]= 0.07 and 1.5, only
in the region where temperatures are larger than 1.* 10^4 K. This region,
between the chromosphere and transition region, has been indicated as a good
candidate for processes that might be responsible for strong variations of
[He]. The set of our observables can still be well reproduced in both cases
changing the atmospheric structure mainly in the low transition region. This
implies that,to choose between different values of [He], it is necessary to
constrain the transition region with different observables, independent on the
He lines.


title: Dark Matter on Galactic Scales (or the Lack Thereof)

abstract:
  This paper presents a brief review of the evidence for dark matter in the
Universe on the scales of galaxies. In the interests of critically and
objectively testing the dark matter paradigm on these scales, this evidence is
weighed against that from the only other game in town, modified Newtonian
dynamics. The verdict is not as clear cut as one might have hoped.


title:
The constraints on power spectrum of relic gravitational waves from
  current observations of large-scale structure of the Universe

abstract:
  We carry out the determination of the amplitude of relic gravitational waves
power spectrum. Indirect best-fit technique was applied to compare
observational data and theory predictions. As observations we have used data on
large-scale structure (LSS) of the Universe and anisotropy of cosmic microwave
background (CMB) temperature. The conventional inflationary model with 11
parameters has been investigated, all of them evaluated jointly. This approach
gave us a possibility to find parameters of power spectrum of gravitational
waves along with statistical errors. The main result consists in following:
WMAP data on power spectrum of CMB temperature fluctuations along with LSS data
prefer model with small amplitude of tensor mode power spectrum, close to zero.
The upper limit for its amplitude at quadupole harmonics T/S=0.6 at 95% C.L.


title: Sensitivity of the EDELWEISS WIMP search to spin-dependent interactions

abstract:
  The EDELWEISS collaboration is searching for WIMP dark matter using natural
Ge cryogenic detectors. The whole data set of the first phase of the experiment
contains a fiducial exposure of 4.8 kg.day on Ge-73, the naturally present
(7.8%), high-spin Ge isotope. The sensitivity of the experiment to the
spin-dependent WIMP-nucleon interactions is evaluated using the
model-independent framework proposed by Tovey et al.


title:
Particle-In-Cell simulations of circularly polarised Alfv\'en wave phase
  mixing: a new mechanism for electron acceleration in collisionless plasmas

abstract:
  In this work we used Particle-In-Cell simulations to study the interaction of
circularly polarised Alfv\'en waves with one dimensional plasma density
inhomogeneities transverse to the uniform magnetic field (phase mixing) in
collisionless plasmas. In our preliminary work we reported discovery of a new
electron acceleration mechanism, in which progressive distortion of the
Alfv\'en wave front, due to the differences in local Alfv\'en speed, generates
an oblique (nearly parallel to the magnetic field) electrostatic field. The
latter accelerates electrons through the Landau resonance. Here we report a
detailed study of this novel mechanism, including: (i) analysis of broadening
of the ion distribution function due to the presence of Alfv\'en waves and (ii)
the generation of compressive perturbations due to both weak non-linearity and
plasma density inhomogeneity. The amplitude decay law in the inhomogeneous
regions, in the kinetic regime, is demonstrated to be the same as in the MHD
approximation described by Heyvaerts and Priest (1983).


title:
Bending Instability of Stellar Disks: The Stabilizing Effect of a
  Compact Bulge

abstract:
  The saturation conditions for bending modes in inhomogeneous thin stellar
disks that follow from an analysis of the dispersion relation are compared with
those derived from $N$-body simulations. In the central regions of
inhomogeneous disks, the reserve of disk strength against the growth of bending
instability is smaller than that for a homogeneous layer. The spheroidal
component (a dark halo, a bulge) is shown to have a stabilizing effect. The
latter turns out to depend not only on the total mass of the spherical
component, but also on the degree of mass concentration toward the center. We
conclude that the presence of a compact (not necessarily massive) bulge in
spiral galaxies may prove to be enough to suppress the bending perturbations
that increase the disk thickness. This conclusion is corroborated by our
$N$-body simulations in which we simulated the evolution of almost equilibrium,
but unstable finite-thickness disks in the presence of spheroidal components.
The final disk thickness at the same total mass of the spherical component
(dark halo + bulge) has been found to be much smaller than that in the
simulations where a concentrated bulge is present.


title: The Evolution of [OII] Emission from Cluster Galaxies

abstract:
  We investigate the evolution of the star formation rate in cluster galaxies.
We complement data from the CNOC1 cluster survey (0.15<z<0.6) with measurements
from galaxy clusters in the 2dF galaxy redshift survey (0.05<z<0.1) and
measurements from recently published work on higher redshift clusters, up to
almost z=1. We focus our attention on galaxies in the cluster core, ie.
galaxies with r<0.7h^{-1}_{70}Mpc. Averaging over clusters in redshift bins, we
find that the fraction of galaxies with strong [OII] emission is < 20% in
cluster cores, and the fraction evolves little with redshift. In contrast,
field galaxies from the survey show a very strong increase over the same
redshift range. It thus appears that the environment in the cores of rich
clusters is hostile to star formation at all the redshifts studied. We compare
this result with the evolution of the colours of galaxies in cluster cores,
first reported by Butcher & Oemler (1984). Using the same galaxies for our
analysis of the [OII] emission, we confirm that the fraction of blue galaxies,
which are defined as galaxies 0.2 mag bluer in the rest frame B-V than the red
sequence of each cluster, increases strongly with redshift. Since the colours
of galaxies retain a memory of their recent star formation history, while
emission from the [OII] line does not, we suggest that these two results can
best be reconciled if the rate at which the clusters are being assembled is
higher in the past, and the galaxies from which it is being assembled are
typically bluer.


title:
'Sculptor'-ing the Galaxy? The Chemical Compositions of Red Giants in
  the Sculptor Dwarf Spheroidal Galaxy

abstract:
  We have used high-resolution, high signal-to-noise spectra obtained with the
VLT and UVES to determine abundances of 17 elements in 4 red giants in the
Sculptor dwarf spheroidal galaxy. Our [Fe/H] values range from --2.10 to
--0.97, confirming previous findings of a large metallicity spread. We have
combined our data with similar data for five Sculptor giants studied recently
to form one of the largest samples of high resolution abundances yet obtained
for a dwarf spheroidal galaxy, covering essentially the full known metallicity
range. These properties allow us to establish trends of [X/Fe] with [Fe/H] for
many elements, X. The trends are significantly different from the trends seen
in galactic halo and globular cluster stars. We compare our Sculptor sample to
their most similar Galactic counterparts and find substantial differences
remain even with these stars. The many discrepancies in the relationships
between [X/Fe] as seen in Sculptor compared with Galactic field stars indicates
that our halo cannot be made up in bulk of stars similar to those presently
seen in dwarf spheroidal galaxies like Sculptor. These results have serious
implications for the Searle-Zinn and hierarchical galaxy formation scenarios.
We also find that the most metal-rich star in our sample is a heavy
element-rich star. A very high percentage of such heavy element stars are now
known in dwarf spheroidals compared to the halo, further mitigating against the
formation of the halo from such objects.


title:
Indication for Primordial Anisotropies in the Neutrino Background from
  WMAP and SDSS

abstract:
  We demonstrate that combining Cosmic Microwave Background anisotropy
measurements from the 1st year WMAP observations with clustering data from the
SLOAN galaxy redshift survey yields an indication for primordial anisotropies
in the cosmological Neutrino Background.


title: Abundances as Tracers of the Formation and Evolution of (Dwarf) Galaxies

abstract:
  This aims to be an overview of what detailed observations of individual stars
in nearby dwarf galaxies may teach us about galaxy evolution. This includes
some early results from the DART (Dwarf Abundances and Radial velocity Team)
Large Programme at ESO. This project has used 2.2m/WFI and VLT/FLAMES to obtain
spectra of large samples of individual stars in nearby dwarf spheroidal
galaxies and determine accurate abundances and kinematics. These results can be
used to trace the formation and evolution of nearby galaxies from the earliest
times to the present.