title: Saving Planetary Systems: Dead Zones & Planetary Migration

abstract:
  The tidal interaction between a disk and a planet leads to the planet's
migration. A long-standing question regarding this mechanism is how to stop the
migration before planets plunge into their central stars. In this paper, we
propose a new, simple mechanism to significantly slow down planet migration,
and test the possibility by using a hybrid numerical integrator to simulate the
disk-planet interaction. The key component of the scenario is the role of low
viscosity regions in protostellar disks known as dead zones, which affect
planetary migration in two ways. First of all, it allows a smaller-mass planet
to open a gap, and hence switch the faster type I migration to the slower type
II migration. Secondly, a low viscosity slows down type II migration itself,
because type II migration is directly proportional to the viscosity. We present
numerical simulations of planetary migration by using a hybrid symplectic
integrator-gas dynamics code. Assuming that the disk viscosity parameter inside
the dead zone is (alpha=1e-4-1e-5), we find that, when a low-mass planet (e.g.
1-10 Earth masses) migrates from outside the dead zone, its migration is
stopped due to the mass accumulation inside the dead zone. When a low-mass
planet migrates from inside the dead zone, it opens a gap and slows down its
migration. A massive planet like Jupiter, on the other hand, opens a gap and
slows down inside the dead zone, independent of its initial orbital radius. The
final orbital radius of a Jupiter mass planet depends on the dead zone's
viscosity. For the range of alpha's noted above, this can vary anywhere from 7
AU, to an orbital radius of 0.1 AU that is characteristic of the hot Jupiters.


title: Extended inverse-Compton emission from distant, powerful radio galaxies

abstract:
  We present Chandra observations of two relatively high redshift FRII radio
galaxies, 3C 432 and 3C 191 (z=1.785 and z=1.956 respectively), both of which
show extended X-ray emission along the axis of the radio jet or lobe. This
X-ray emission is most likely to be due to inverse-Compton scattering of Cosmic
Microwave Background (CMB) photons. Under this assumption we estimate the
minimum energy contained in the particles responsible. This can be extrapolated
to determine a rough estimate of the total energy. We also present new, deep
radio observations of 3C 294, which confirm some association between radio and
X-ray emission along the NE-SW radio axis and also that radio emission is not
detected over the rest of the extent of the diffuse X-ray emission. This,
together with the offset between the peaks of the X-ray and radio emissions may
indicate that the jet axis in this source is precessing.


title:
High Order Correction Terms for The Peak-Peak Correlation Function in
  Nearly-Gaussian Models

abstract:
  One possible way to investigate the nature of the primordial power spectrum
fluctuations is by investigating the statistical properties of the local
maximum in the density fluctuation fields. In this work we present a study of
the mean correlation function, $\xi_r$, and the correlation function for high
amplitude fluctuations (the peak-peak correlation) in a slighlty non-Gaussian
context. From the definition of the correlation excess, we compute the Gaussian
two-point correlation function and, using an expansion in Generalized Hermite
polynomials, we estimate the correlation of high density peaks in a
non-Gaussian field with generic distribution and power spectrum. We also apply
the results obtained to a scale-mixed distribution model, which correspond to a
nearly Gaussian model. The results reveal that, even for a small deviation from
Gaussianity, we can expect high density peaks to be much more correlated than
in a Gaussian field with the same power spectrum. In addition, the calculations
reveal how the amplitude of the peaks in the fluctuations field is related to
the existing correlations. Our results may be used as an additional tool to
investigate the behavior of the N-point correlation function, to understand how
non-Gaussian correlations affect the peak-peak statistics and extract more
information about the statistics of the density field.


title: Is the SMC Bound to the LMC? The HST Proper Motion of the SMC

abstract:
  We present a measurement of the systemic proper motion of the Small
Magellanic Cloud (SMC) made using the Advanced Camera for Surveys (ACS) on the
\textit{Hubble Space Telescope} (\textit{HST}). We tracked the SMC's motion
relative to 4 background QSOs over a baseline of approximately 2 years. The
measured proper motion is : $\mu_W = -1.16 \pm 0.18 \masyr, \mu_N = -1.17 \pm
0.18 \masyr$. This is the best measurement yet of the SMC's proper motion. We
combine this new result with our prior estimate of the proper motion of the
Large Magellanic Cloud (LMC) from the same observing program to investigate the
orbital evolution of both Clouds over the past 9 Gyr. The current relative
velocity between the Clouds is $105 \pm 42 \kms$. Our investigations of the
past orbital motions of the Clouds in a simple model for the dark halo of the
Milky Way imply that the Clouds could be unbound from each other. However, our
data are also consistent with orbits in which the Clouds have been bound to
each other for approximately a Hubble time. Smaller proper motion errors and
better understanding of the LMC and SMC masses would be required to constrain
their past orbital history and their bound vs. unbound nature unambiguously.
The new proper motion measurements should be sufficient to allow the
construction of improved models for the origin and properties of the Magellanic
Stream. In turn, this will provide new constraints on the properties of the
Milky Way dark halo.


title: SZ Surveys are Coming: What should we do?

abstract:
  Galaxy clusters furnish extremely rich information on the contents and
structure of our universe. The potential of galaxy cluster studies to constrain
dark energy, for example, motivates a number of ambitious cluster surveys.
Among these, surveys based on the Sunyaev-Zel'dovich (SZ) effect are
particularly powerful for their ability to cleanly select clusters out to
redshifts z>1. Now poised to begin surveying substantial areas of sky,
dedicated interferometers, bolometer cameras and the Planck satellite will soon
produce large cluster catalogs that will provide a precise measure of the
cosmic expansion rate over a range of redshifts and precipitate a new
understanding of structure and galaxy formation. I review the science potential
of these surveys and examine some issues of SZ cluster catalog construction.


title: Entrainment Mechanisms for Outflows in the L1551 Star-Forming Region

abstract:
  We present high sensitivity 12/13CO(1-0) molecular line maps covering the
full extent of the parsec scale L1551 molecular outflow, including the
redshifted east-west (EW) flow. We also present 12CO(3-2) data that extends
over a good fraction of the area mapped in the 1-0 transition. We compare the
molecular data to widefield, narrow-band optical emission in H$\alpha$. While
there are multiple outflows in the L1551 cloud, the main outflow is oriented at
50\arcdeg position angle and appears to be driven by embedded source(s) in the
central IRS 5 region. The 3-2 data indicate that there may be molecular
emission associated with the L1551 NE jet, within the redshifted lobe of main
outflow. We have also better defined the previously known EW flow and believe
we have identified its blueshifted counterpart. We further speculate that the
origin of the EW outflow lies near HH 102. We use velocity dependent opacity
correction to estimate the mass and the energy of the outflow. The resulting
mass spectral indices from our analysis, are systematically lower (less steep)
than the power law indices obtained towards other outflows in several recent
studies that use a similar opacity correction method. We show that systematic
errors and biases in the analysis procedures for deriving mass spectra could
result in errors in the determination of the power-law indices. The mass
spectral indices, the morphological appearance of the position-velocity plots
and integrated intensity emission maps of the molecular data, compared with the
optical, suggest that jet-driven bow-shock entrainment is the best explanation
for the driving mechanism of outflows in L1551. The kinetic energy of the
outflows is found to be comparable to the binding energy of the cloud and
sufficient to maintain the turbulence in the L1551 cloud.


title: C stars in the outer spheroid of NGC 6822

abstract:
  From a 2 x 2 degree survey of NGC 6822 we have previously established that
this Local Group dwarf irregular galaxy possesses a huge spheroid having more
than one degree in length. This spheroid is in rotation but its rotation curve
is known only within ~15' from the center. It is therefore critical to identify
bright stars belonging to the spheroid to characterize, as far as possible, its
outer kinematics. We use the new wide field near infrared imager CPAPIR,
operated by the SMARTS consortium, to acquire J, Ks images of two 34.8' x 34.8'
areas in the outer spheroid to search for C stars. The colour diagram of the
fields allows the identification of 192 C stars candidates but a study of the
FWHM of the images permits the rejection of numerous non-stellar objects with
colours similar to C stars. We are left with 75 new C stars, their mean Ks
magnitude and mean colour are similar to the bulk of known NGC 6822 C stars.
This outer spheroid survey confirms that the intermediate-age AGB stars are a
major contributor to the stellar populations of the spheroid. The discovery of
some 50 C stars well beyond the limit of the previously known rotation curve
calls for a promising spectroscopic follow-up to a major axis distance of 40'.


title:
Far-Ultraviolet Imaging of the Hubble Deep Field North: Star Formation
  in Normal Galaxies at z<1

abstract:
  We present far-ultraviolet (FUV) imaging of the Hubble Deep Field North
(HDF-N) taken with the Solar Blind Channel of the Advanced Camera for Surveys
(ACS/SBC) and the FUV MAMA detector of the Space Telescope Imaging Spectrograph
(STIS) onboard the Hubble Space Telescope. The full WFPC2 deep field has been
observed at 1600 Angstroms. We detect 134 galaxies and one star down to a limit
of FUV_{AB} ~ 29. All sources have counterparts in the WFPC2 image. Redshifts
(spectroscopic or photometric) for the detected sources are in the range 0<z<1.
We find that the FUV galaxy number counts are higher than those reported by
GALEX, which we attribute at least in part to cosmic variance in the small
HDF-N field of view. Six of the 13 Chandra sources at z<0.85 in the HDF-N are
detected in the FUV, and those are consistent with starbursts rather than AGN.
Cross-correlating with Spitzer sources in the field, we find that the FUV
detections show general agreement with the expected L_IR/L_UV vs. Beta
relationship. We infer star formation rates (SFRs), corrected for extinction
using the UV slope, and find a median value of 0.3 Msun/yr for FUV-detected
galaxies, with 75% of detected sources have SFR<1 Msun/yr. Examining the
morphological distribution of sources, we find that about half of all
FUV-detected sources are identied as spiral galaxies. Half of
morphologically-selected spheroids at z<0.85 are detected in the FUV,
suggesting that such sources have significant ongoing star-formation in the
epoch since z=1.


title: The new pre-cataclysmic binary PG 2200+085

abstract:
  We present the results of spectroscopic-- and orbit--sampled photometric
observations of the faint UV-excess object PG 2200+085. The optical CCD
photometry observations of this object were performed by the Russian-Turkish
1.5-meter telescope RTT150 at the TUBITAK National Observatory (Turkey). The
long-slit optical spectroscopy observations with 2.6 A resolution were carried
out by 6-meter telescope BTA at the Special Astrophysical Observatory (Russia).
The photometric variations over two nights are almost sinusoidal with an
amplitude \Delta m_V = 0.04 m and a period of P = 0.3186 d. Such a light curve
is typical of a detached close binary with an illumination effect or the
ellipsoidal deformation of a secondary star. The observed spectrum clearly
displays a featureless blue continuum of a hot component and a rich
absorption--line and molecular band K--star spectrum. The CaII line profiles
with strong emission cores are remarkably similar to those of V471 Tau. We
tentatively classify PG 2200+085 as a pre-cataclysmic binary of the V471 Tau
type.


title: The Magellanic Stream in Modified Newtonian Dynamics

abstract:
  The dynamics of the Magellanic Stream (MS) as a series of clouds extending
from the Magellanic Clouds (MCs) to the south Galactic pole is affected by the
distribution and the amount of matter in the Milky Way. We calculate the
gravitational effect of the Galactic disk on the MS in the framework of
modified Newtonian dynamics(MOND) and compare with observations of the Stream's
radial velocity. We consider the tidal force of the Galaxy, which strips
material from the MCs to form the MS, and, using a no-halo model of the Galaxy,
we ignore the effect of the drag of the Galactic halo on the MS. We also
compare the MONDian dynamics with that in logarithmic and power-law dark halo
models and show that the MOND theory seems plausible for describing the
dynamics of satellite galaxies such as the MCs. Finally, we perform a maximum
likelihood analysis to obtain the best MOND parameters for the Galactic disk.


title: Bayesian Estimation of Hardness Ratios: Modeling and Computations

abstract:
  A commonly used measure to summarize the nature of a photon spectrum is the
so-called Hardness Ratio, which compares the number of counts observed in
different passbands. The hardness ratio is especially useful to distinguish
between and categorize weak sources as a proxy for detailed spectral fitting.
However, in this regime classical methods of error propagation fail, and the
estimates of spectral hardness become unreliable. Here we develop a rigorous
statistical treatment of hardness ratios that properly deals with detected
photons as independent Poisson random variables and correctly deals with the
non-Gaussian nature of the error propagation. The method is Bayesian in nature,
and thus can be generalized to carry out a multitude of
source-population--based analyses. We verify our method with simulation
studies, and compare it with the classical method. We apply this method to real
world examples, such as the identification of candidate quiescent Low-mass
X-ray binaries in globular clusters, and tracking the time evolution of a flare
on a low-mass star.


title:
Effect on cosmic microwave background polarization of coupling of
  quintessence to pseudoscalar formed from the electromagnetic field and its
  dual

abstract:
  We present the full set of power spectra of cosmic microwave background (CMB)
temperature and polarization anisotropies due to the coupling between
quintessence and pseudoscalar of electromagnetism. This coupling induces the
rotation of the polarization plane of CMB photons, thus resulting in
non-vanishing B mode and parity-violating TB and EB modes. Using the 2003
flight of BOOMERANG (B03) data, we give the most stringent constraint on the
coupling strength. In some cases, the rotation-induced B mode can confuse the
hunting for the gravitational lensing induced B mode.


title:
Cosmological constraints on a dark energy model with a non-linear scalar
  field

abstract:
  In the present work we study a dark energy model in which a non-linear scalar
field (tachyon) with a Born-Infeld type of action is responsible for the
observed cosmic acceleration. The potential of the tachyon is well-motivated
since it comes from open string theory and the model is subjected to various
cosmological constraints with data coming from supernovae as well as from
microwave background radiation. Our analysis shows that in the particular model
under study the tachyon can be an excellent candidate for dark energy in the
universe, as the model agrees with a series of observational data and for a
wide range of the parameters of the model.


title:
ELTs Adaptive Optics for Multi-Objects 3D Spectroscopy : Key Parameters
  and Design Rules

abstract:
  In the last few years, new Adaptive Optics [AO] techniques have emerged to
answer new astronomical challenges: Ground-Layer AO [GLAO] and Multi-Conjugate
AO [MCAO] to access a wider Field of View [FoV], Multi-Object AO [MOAO] for the
simultaneous observation of several faint galaxies, eXtreme AO [XAO] for the
detection of faint companions. In this paper, we focus our study to one of
these applications : high red-shift galaxy observations using MOAO techniques
in the framework of Extremely Large Telescopes [ELTs]. We present the
high-level specifications of a dedicated instrument. We choose to describe the
scientific requirements with the following criteria : 40% of Ensquared Energy
[EE] in H band (1.65um) and in an aperture size from 25 to 150 mas. Considering
these specifications we investigate different AO solutions thanks to Fourier
based simulations. Sky Coverage [SC] is computed for Natural and Laser Guide
Stars [NGS, LGS] systems. We show that specifications are met for NGS-based
systems at the cost of an extremely low SC. For the LGS approach, the option of
low order correction with a faint NGS is discussed. We demonstrate that, this
last solution allows the scientific requirements to be met together with a
quasi full SC.


title: A hot transient outflow from eta Carinae

abstract:
  eta Carinae is a stellar binary system with a period of 5.54 years. It
harbors one of the brightest and most massive stars in our galaxy. This paper
presents spectroscopic evidence for a fast (up to 2,000 km/s) X-ray outflow of
ionized gas launched from eta Carinae just before what is believed to be the
binary periastron (point of smallest binary separation). The appearance of this
high-velocity component, just as the irregular flares in the X-ray light curve,
can not be explained by the simple continuous binary wind interaction, adding
to the intrigue of the eta Carinae system.


title: Modelling of the spectra and atmospheres of evolved stars

abstract:
  The method and results of the computation of the model atmospheres and
spectral energy distributions of chemically peculiar stars, are discussed. The
models are computed with a special consideration of the particular problems
encountered when computing model atmospheres for M and C-giants, and of
hydrogen deficient stars. We present some computed model atmospheres for
Sakurai's object, giants of globular clusters, and C-giants.


title: Faint X-ray Sources in the Globular Cluster Terzan 5

abstract:
  We report our analysis of a Chandra X-ray observation of the rich globular
cluster Terzan 5, in which we detect 50 sources to a limiting 1.0-6 keV X-ray
luminosity of 3*10^{31} ergs/s within the half-mass radius of the cluster.
Thirty-three of these have L_X>10^{32} ergs/s, the largest number yet seen in
any globular cluster. In addition to the quiescent low-mass X-ray binary (LMXB,
identified by Wijnands et al.), another 12 relatively soft sources may be
quiescent LMXBs. We compare the X-ray colors of the harder sources in Terzan 5
to the Galactic Center sources studied by Muno and collaborators, and find the
Galactic Center sources to have harder X-ray colors, indicating a possible
difference in the populations. We cannot clearly identify a metallicity
dependence in the production of low-luminosity X-ray binaries in Galactic
globular clusters, but a metallicity dependence of the form suggested by Jordan
et al. for extragalactic LMXBs is consistent with our data.


title: Spinning-Down of Moving Magnetars in the Propeller Regime

abstract:
  We use axisymmetric magnetohydrodynamic simulations to investigate the
spinning-down of magnetars rotating in the propeller regime and moving
supersonically through the interstellar medium. The simulations indicate that
magnetars spin-down rapidly due to this interaction, faster than for the case
of a non-moving star. From many simulation runs we have derived an approximate
scaling laws for the angular momentum loss rate, \dot{L} \propto
\~\eta_m^{0.3}\mu^{0.6}\rho^{0.8}{\cal M}^{-0.4} \Omega_*^{1.5}, where \rho is
the density of the interstellar medium, \cal M is Mach number, \mu is the
star's magnetic moment, \Omega_* is its angular velocity, and \eta_m is
magnetic diffusivity. A magnetar with a surface magnetic field of 10^{13} -
10^{15} G is found to spin-down to a period P > 10^5-10^6 s in \sim 10^4 - 10^5
years. There is however uncertainty about the value of the magnetic diffusivity
so that the time-scale may be longer. We discuss this model in respect of Soft
Gamma Repeaters (SGRs) and the isolated neutron star candidate RXJ1856.5-3754.


title:
Confronting X-ray Emission Models with the Highest-Redshift
  Kiloparsec-scale Jets: the z=3.89 Jet in Quasar 1745+624

abstract:
  A newly identified kiloparsec-scale X-ray jet in the high-redshift z=3.89
quasar 1745+624 is studied with multi-frequency Very Large Array, Hubble Space
Telescope, and Chandra X-ray imaging data. This is only the third large-scale
X-ray jet beyond z>3 known and is further distinguished as being the most
luminous relativistic jet observed at any redshift, exceeding 10^45 erg/s in
both the radio and X-ray bands. Apart from the jet's extreme redshift,
luminosity, and high inferred equipartition magnetic field (in comparison to
local analogues), its basic properties such as X-ray/radio morphology and radio
polarization are similar to lower-redshift examples. Its resolved linear
structure and the convex broad-band spectral energy distributions of three
distinct knots are also a common feature among known powerful X-ray jets at
lower-redshift. Relativistically beamed inverse Compton and `non-standard'
synchrotron models have been considered to account for such excess X-ray
emission in other jets; both models are applicable to this high-redshift
example but with differing requirements for the underlying jet physical
properties, such as velocity, energetics, and electron acceleration processes.
One potentially very important distinguishing characteristic between the two
models is their strongly diverging predictions for the X-ray/radio emission
with increasing redshift. This is considered, though with the limited sample of
three z>3 jets it is apparent that future studies targeted at very
high-redshift jets are required for further elucidation of this issue. Finally,
from the broad-band jet emission we estimate the jet kinetic power to be no
less than 10^46 erg/s, which is about 10% of the Eddington luminosity
corresponding to this galaxy's central [abridged]


title: Large-Scale Radio and X-ray Jets in the Highest Redshift Quasars

abstract:
  We describe our program to search for and study the kilo-parsec scale radio
jets in a sample of high-redshift (greater than 3.4), flat spectrum quasars
using new and archival VLA data. Two of these radio jets have been imaged with
Chandra, and have X-ray counterparts and are briefly discussed. These
high-redshift sources are important targets for testing current X-ray jet
emission models for kpc-scale jets and follow-up multi-wavelength observations
will shed light on this problem.


title: V605 Aql: The Older Twin of Sakurai's Object

abstract:
  New optical spectra have been obtained with VLT/FORS2 of the final helium
shell flash (FF) star, V605 Aql, which peaked in brightness in 1919. New models
suggest that this star is experiencing a very late thermal pulse. The evolution
to a cool luminous giant and then back to a compact hot star takes place in
only a few years. V605 Aql, the central star of the Planetary Nebula (PN), A58,
has evolved from T$_{eff}\sim$5000 K in 1921 to $\sim$95,000 K today. There are
indications that the new FF star, Sakurai's Object (V4334 Sgr), which appeared
in 1996, is evolving along a similar path. The abundances of Sakurai's Object
today and V605 Aql 80 years ago mimic the hydrogen deficient R Coronae Borealis
(RCB) stars with 98% He and 1% C. The new spectra show that V605 Aql has
stellar abundances similar to those seen in Wolf-Rayet [WC] central stars of
PNe with ~55% He, and ~40% C. The stellar spectrum of V605 Aql can be seen even
though the star is not directly detected. Therefore, we may be seeing the
spectrum in light scattered around the edge of a thick torus of dust seen
edge-on. In the present state of evolution of V605 Aql, we may be seeing the
not too distant future of Sakurai's Object.


title: Simulation studies of CZT Detectors as Gamma-Ray Calorimeter

abstract:
  We describe the results of detailed 3-D Monte Carlo simulations of a "CZT
calorimeter" that can be used to detect photons in the keV to several MeV
range. Several astrophysics applications require the detection of photons in
the energy range of keV up to several MeV with good position and energy
resolution. For certain applications Cadmium Zinc Telluride (CZT) detectors
might be the detector option of choice. Up to now, CZT detectors have mainly
been used in the energy range between a few keV to ~1 MeV, we describe the
results of detailed 3-D Monte Carlo simulations of a "CZT calorimeter" that can
be used to detect photons in the keV to several MeV range. The main objective
of these studies is to evaluate the feasibility of CZT calorimeters, to study
their performance and detect and understand performance limiting factors. Such
a calorimeter consists of many layers of closely packed pixellated CZT detector
units. Our simulations of single detector units reproduce experimental results,
indicating that our simulations capture the main factors that limit the
performance of a detector unit. Overall the conclusion of our simulation study
is that between 1 cm and 1.5 cm thick detector units can be used to build a
calorimeter with good performance over the energy range from ~20 keV to ~10
MeV.


title:
The Anomalous X-Ray Pulsar 4U 0142+61: A Neutron Star with a Gaseous
  Fallback Disk

abstract:
  The recent detection of the anomalous X-ray pulsar (AXP) 4U 0142+61 in the
mid-infrared with the {\it Spitzer} observatory by Z.Wang and coworkers
constitutes the first instance of a disk around an AXP. We show, by analyzing
earlier optical and near-IR data together with the recent data, that the
overall broadband data set can be reproduced by a single model of an irradiated
and viscously heated disk.


title:
RASS-SDSS Galaxy Cluster Survey. VII. On the Cluster Mass to Light ratio
  and the Halo Occupation Distribution

abstract:
  We explore the mass-to-light ratio in galaxy clusters and its relation to the
cluster mass. We study the relations among the optical luminosity ($L_{op}$),
the cluster mass ($M_{200}$) and the number of cluster galaxies within
$r_{200}$ ($N_{gal}$) in a sample of 217 galaxy clusters with confirmed 3D
overdensity. We correct for projection effects, by determining the galaxy
surface number density profile in our cluster sample. This is best fitted by a
cored King profile in low and intermediate mass systems. The core radius
decreases with cluster mass, and, for the highest mass clusters, the profile is
better represented by a generalized King profile or a cuspy Navarro, Frenk &
White profile. We find a very tight proportionality between $L_{op}$ and
$N_{gal}$, which, in turn, links the cluster mass-to-light ratio to the Halo
Occupation Distribution $N_{gal}$ vs. $M_{200}$. After correcting for
projection effects, the slope of the $L_{op}-M_{200}$ and $N_{gal}-M_{200}$
relations is found to be $0.92\pm0.03$, close, but still significantly less
than unity. We show that the non-linearity of these relations cannot be
explained by variations of the galaxy luminosity distributions and of the
galaxy M/L with the cluster mass. We suggest that the nonlinear relation
between number of galaxies and cluster mass reflects an underlying nonlinear
relation between number of subhaloes and halo mass.


title:
Neutral hydrogen in nearby elliptical and lenticular galaxies: the
  continuing formation of early-type galaxies

abstract:
  (Abridged) We present deep WSRT observations of neutral hydrogen in 12 nearby
elliptical and lenticular galaxies. The selected objects come from a
representative sample of nearby galaxies earlier studied at optical wavelengths
with the integral-field spectrograph Sauron. We detect HI - both in regular
discs as well as in clouds and tails off-set from the host galaxy - in 70% of
the galaxies. This detection rate is much higher than in previous, shallower
single-dish surveys, and is similar to that for the ionised gas. The results
suggest that at faint detection levels the presence of HI is a relatively
common characteristic of field early-type galaxies. The observed total HI
masses range between a few times 10^6 Msun to just over 10^9 Msun. The presence
of regular disc-like structures is a situation as common as HI in offset clouds
and tails around early-type galaxies. All galaxies where HI is detected also
contain ionised gas, whereas no HI is found around galaxies without ionised
gas. Galaxies with regular HI discs tend to have strong emission from ionised
gas. In these cases, the similar kinematics of the neutral hydrogen and ionised
gas suggest that they form one structure. We do not find a clear trend between
the presence of HI and the global age of the stellar population or the global
dynamical characteristics of the galaxies. Our observations support the idea
that gas accretion is common and does not happen exclusively in peculiar
early-type galaxies. For the majority of the cases the gas is likely acquired
through merging, but the lack of correlation with the stellar population age
suggests that smooth, cold accretion could be an alternative scenario, at least
in some galaxies. In either cases, the data suggest that early-type galaxies
continue to build their mass up to the present.


title: On the X-ray spectra of luminous, inhomogeneous accretion flows

abstract:
  We discuss the expected X-ray spectral and variability properties of black
hole accretion discs at high luminosity, under the hypothesis that radiation
pressure dominated discs are subject to violent clumping instabilities and, as
a result, have a highly inhomogeneous two-phase structure. After deriving the
full accretion disc solutions explicitly in terms of the parameters of the
model, we study their radiative properties both with a simple two-zones model,
treatable analytically, and with radiative transfer simulations which account
simultaneously for energy balance and Comptonisation in the hot phase, together
with reflection, reprocessing, ionization and thermal balance in the cold
phase. We show that, if not only the density, but also the heating rate within
these flows is inhomogeneous, then complex reflection-dominated spectra can be
obtained for a high enough covering fraction of the cold phase. In general,
large reflection components in the observed X-ray spectra should be associated
with strong soft excesses, resulting from the combined emission of ionized
atomic emission lines. The variability properties of such systems are such
that, even when contributing to a large fraction of the hard X-ray spectrum,
the reflection component is less variable than the power-law like emission
originating from the hot Comptonising phase, in agreement with what is observed
in many Narrow Line Seyfert 1 galaxies and bright Seyfert 1. Our model falls
within the family of those trying to explain the complex X-ray spectra of
bright AGN with ionized reflection, but presents an alternative, specific,
physically motivated, geometrical setup for the complex multi-phase structure
of the inner regions of near-Eddington accretion flows.


title:
Techniques for reducing fiber-fed and integral-field spectroscopy data:
  The software package R3D

abstract:
  This paper describes the general characteristics of raw data from fiber-fed
spectrographs in general and fiber-fed IFUs in particular. The different steps
of the data reduction are presented, and the techniques used to address the
unusual characteristics of these data are described in detail. These techniques
have been implemented in a specialized software package, R3D, developed to
reduce fiber-based integral field spectroscopy (IFS) data. The package
comprises a set of command-line routines adapted for each of these steps,
suitable for creating pipelines. The routines have been tested against
simulations, and against real data from various integral field spectrographs
(PMAS, PPAK, GMOS, VIMOS and INTEGRAL). Particular attention is paid to the
treatment of cross-talk.


title: A general model for the identification of specific PAHs in the far-IR

abstract:
  Context. In the framework of the interstellar PAH hypothesis, far-IR skeletal
bands are expected to be a fingerprint of single species in this class. Aims. A
detailed model of the photophysics of interstellar PAHs is required for such
single-molecule identification of their far-IR features in the presently
available Infrared Space Observatory data and in those of the forthcoming
Herschel Space Observatory mission. Methods. We modelled the detailed
photophysics of a vast sample of species in different radiation fields, using a
compendium of Monte-Carlo techniques and quantum-chemical calculations. This
enabled us to validate the use of purely theoretical data and assess the
expected accuracy and reliability of the resulting synthetic far-IR emission
spectra. Results. We produce positions and intensities of the expected far-IR
features which ought to be emitted by each species in the sample in the
considered radiation fields. A composite emission spectrum for our sample is
computed for one of the most favourable sources for detection, namely the Red
Rectangle nebula. The resulting spectrum is compared with the estimated dust
emission in the same source, to assess the dependence of detectability on key
molecular parameters. Conclusions. Identifying specific PAHs from their far-IR
features is going to be a difficult feat in general, still it may well be
possible under favourable conditions.


title:
The mean electro-motive force, current- and cross-helicity under the
  influence of rotation, magnetic field and shear

abstract:
  The mean electromotive force (MEMF) in a rotating stratified
magnetohydrodynamical turbulence is studied.Our study rests on the mean-field
magnetohydrodynamics framework and $\tau$ approximation. We compute the effects
of the large-scale magnetic fields (LSMF), global rotation and large-scale
shear flow on the different parts of the MEMF (such as $\alpha$ - effect,
turbulent diffusion, turbulent transport, etc.) in an explicit form. The
influence of the helical magnetic fluctuations which stem from the small-scale
dynamo is taken into account, as well. In the paper, we derive the equation
governing the current helicity evolution. It is shown that the joint effect of
the differential rotation and magnetic fluctuations in the stratified media can
be responsible for the generation, maintenance and redistribution of the
current helicity. The implication of the obtained results to astrophysical
dynamos is considered as well.


title: Ellipsoidal Universe Can Solve The CMB Quadrupole Problem

abstract:
  The recent three-year WMAP data have confirmed the anomaly concerning the low
quadrupole amplitude compared to the best-fit \Lambda CDM prediction. We show
that, allowing the large-scale spatial geometry of our universe to be
plane-symmetric with eccentricity at decoupling or order 10^{-2}, the
quadrupole amplitude can be drastically reduced without affecting higher
multipoles of the angular power spectrum of the temperature anisotropy.


title:
Mean--field electrodynamics: Critical analysis of various analytical
  approaches to the mean electromotive force

abstract:
  There are various analytical approaches to the mean electromotive force $\cal
E =< \vec{u}\times \vec{b}>$ crucial in mean--field electrodynamics, with
$\vec{u}$ and
  $\vec{b}$ being velocity and magnetic field fluctuations. In most cases the
traditional approach, restricted to the second--order correlation
approximation, has been used. Its validity is only guaranteed for a range of
conditions, which is narrow in view of many applications, e.g., in
astrophysics. With the intention to have a wider range of applicability other
approaches have been proposed which make use of the so--called
$\tau$--approximation, reducing correlations of third order in $\vec{u}$ and
$\vec{b}$ to such of second order. After explaining some basic features of the
traditional approach a critical analysis of the approaches of that kind is
given. It is shown that they lead in some cases to results which are in clear
conflict with those of the traditional approach. It is argued that this
indicates shortcomings of the $\tau$--approaches and poses serious restrictions
to their applicability. These shortcomings do not result from the basic
assumption of the $\tau$--approximation. Instead, they seem to originate in
some simplifications made in order to derive $\cal E$ without really solving
the equations governing $\vec{u}$ and $\vec{b}$. A starting point for a new
approach is described which avoids the conflict.


title: Study of Photon Dominated Regions in Cepheus B

abstract:
  Aim: The aim of the paper is to understand the emission from the photon
dominated regions in Cepheus B, estimate the column densities of neutral carbon
in bulk of the gas in Cepheus B and to derive constraints on the factors which
determine the abundance of neutral carbon relative to CO. Methods: This paper
presents 15'x15' fully sampled maps of CI at 492 GHz and 12CO 4-3 observed with
KOSMA at 1' resolution. The new observations have been combined with the FCRAO
12CO 1-0, IRAM-30m 13CO 2-1 and C18O 1-0 data, and far-infrared continuum data
from HIRES/IRAS. The KOSMA-tau spherical PDR model has been used to understand
the CI and CO emission from the PDRs in Cepheus B and to explain the observed
variation of the relative abundances of both C^0 and CO. Results: The emission
from the PDR associated with Cepheus B is primarily at V_LSR between -14 and
-11 km s^-1. We estimate about 23% of the observed CII emission from the
molecular hotspot is due to the ionized gas in the HII region. Over bulk of the
material the C^0 column density does not change significantly, (2.0+-1.4)x10^17
cm^-2, although the CO column density changes by an order of magnitude. The
observed \cbyco abundance ratio varies between 0.06 and 4 in Cepheus B. We find
an anti-correlation of the observed C/CO abundance ratio with the observed
hydrogen column density, which holds even when all previous observations
providing C/CO ratios are included. Here we show that this observed variation
of C/CO abundance with total column density can be explained only by clumpy
PDRs consisting of an ensemble of clumps. At high H2 column densities high mass
clumps, which exhibit low C/CO abundance, dominate, while at low column
densities, low mass clumps with high C/CO abundance dominate.


title: On the distance of GRO J1655-40

abstract:
  We challenge the accepted distance of 3.2 kpc of GRO J1655-40. We present
VLT-UVES spectroscopic observations to estimate the absorption toward the
source, and determine a maximum distance of GRO J1655-40. We show that the
accepted value of 3.2 kpc is taken for granted by many authors. We retrieved in
the ESO archive UVES spectra taken in April 2004 when GRO J1655-40 was in
quiescence to determine the spectral type of the secondary star. For the first
time we build a flux-calibrated mean (UVES) spectrum of GRO J1655-40 and
compare its observed flux to that of five nearby stars of similar spectral
types. We strengthen our results with the traditional pair method, using
published photometric data of the comparison stars. We show that the distance
of 3.2 kpc is questionable. We determine a spectral type F6IV for the secondary
star. We demonstrate in details that the distance of GRO J1655-40 must be
smaller than 1.7 kpc. The runaway black hole GRO J1655-40 could be associated
with the open cluster NGC 6242 which is located at 1.0$\pm$0.1 kpc from the
Sun. At $D \leq$ 1.7 kpc the jets are not a superluminal, and GRO J1655-40
becomes one of the closest known black holes to the Sun.


title:
The remarkable light and colour variability of Small Magellanic Cloud Be
  stars

abstract:
  (Abridged) Some 240 blue stars in the Small Magellanic Cloud are investigated
on their fantastic irregular continuum variability. We report here two results
regarding these stars. First, their optical flux excess is correlated to their
near-IR flux excess, as determined from optical EROSII light curves and 2MASS
measurements. Second, the relation between optical colour and magnitude is
observed to be bi-valued in 40% of the cases, resulting in a "loop" when the
light curve is presented in a colour-magnitude diagram. We argue that optical
variability for a large fraction of the variable stars is due to variations in
the amount of bound-free and free-free radiation. We do simple model
calculations that allow us to interpret the observed colour-magnitude
variability as due to an outflowing ionized circumstellar disk. The mass loss
of the central star is variable, i.e. on or off. Once the star stops losing
mass, the disk evolves naturally into a ring. The observed bi-valued
colour-magnitude relation is the transition of a partially optically thick to a
fully optically thin disk. Significantly, the loop is traversed clockwise by
outflowing matter, but anti-clockwise by infalling matter. It is observed that
the material is generally outflowing, but few cases of inflow are also
observed.


title:
Exploring Halo Substructure with Giant Stars: The Dynamics and
  Metallicity of the Dwarf Spheroidal in Bootes

abstract:
  We report the results of a spectroscopic study of the Bootes (Boo) dwarf
spheroidal (dSph) galaxy carried out with the WIYN telescope and the Hydra
multifiber spectrograph. Radial velocities have been measured for 58 Boo
candidate stars selected to have magnitudes and colors consistent with its red
and asymptotic giant branches. Within the 13' half-light radius, seven members
of Boo yield a systemic velocity of V_r=95.6+-3.4 km/s and a velocity
dispersion of 6.6+-2.3 km/s. This implies a mass on the order of 1 x 10^7
M_sun, similar to the inferred masses of other Galactic dSphs. Adopting a total
Boo luminosity of L=1.8 x 10^4 L_sun to 8.6 x 10^4 L_sun implies M/L ~ 610 to
130, making Boo, the most distorted known Milky Way dwarf galaxy, potentially
also the darkest. From the spectra of Boo member stars we estimate its
metallicity to be [Fe/H] ~ -2.5, which would make it the most metal poor dSph
known to date.


title: The highly ionized disk wind of GRO J1655-40

abstract:
  Aims: The galactic superluminal microquasar GRO J1655-40 started a new
outburst in February 2005, after seven years in quiescence, rising to a
high/soft state in March 2005. In this paper we study the X-ray spectra during
this rise. Methods: We observed GRO J1655-40 with XMM-Newton, on 27 February
2005, in the low/hard state, and on three consecutive days in March 2005,
during the rise of the source to its high/soft state. The EPIC-pn camera was
used in the fast-read Burst mode to avoid photon pile-up. Results: First, we
contributed to the improvement of the calibration of the EPIC-pn, since the
high flux received from the source required some refinements in the correction
of the Charge Transfer Efficiency of the camera.Second, we find that the X-ray
spectrum of GRO J1655-40 is dominated in the high/soft state by the thermal
emission from the accretion disk, with an inner radius of 13-14(D/3.2kpc)km and
a maximum temperature of 1.3 keV. Two absorption lines are detected in the
EPIC-pn spectra, at 6.7-6.8 and 7.8-8.0 keV, which can be identified either as
blended Fe XXV and Fe XXVI K-alpha and K-beta lines, or as blueshifted Fe XXV.
We find no orbital dependence on the X-ray properties, which provides an upper
limit for the inclination of the system of 73 degr. The RGS spectrometers
reveal interstellar absorption features at 17.2AA, 17.5AA (Fe L edges) and
23.54AA (OI K-alpha). Finally, while checking the interstellar origin of the OI
line, we find a general correlation of the OI K-alpha line equivalent width
with the hydrogen column density using several sources available in the
literature.


title: On the weakness of disc models in bright ULXs

abstract:
  It is sometimes suggested that phenomenological power-law plus cool
disc-blackbody models represent the simplest, most robust interpretation of the
X-ray spectra of bright ultraluminous X-ray sources (ULXs); this has been taken
as evidence for the presence of intermediate-mass black holes (BHs) (M ~ 10^3
Msun) in those sources. Here, we assess this claim by comparing the cool
disc-blackbody model with a range of other models. For example, we show that
the same ULX spectra can be fitted equally well by subtracting a disc-blackbody
component from a dominant power-law component, thus turning a soft excess into
a soft deficit. Then, we propose a more complex physical model, based on a
power-law component slightly modified at various energies by smeared emission
and absorption lines from highly-ionized, fast-moving gas. We use the
XMM-Newton/EPIC spectra of two ULXs in Holmberg II and NGC 4559 as examples.
Our main conclusion is that the presence of a soft excess or a soft deficit
depends on the energy range over which we choose to fit the ``true'' power-law
continuum; those small deviations from the power-law spectrum are well modelled
by disc-blackbody components (either in emission or absorption) simply because
they are a versatile fitting tool for most kinds of smooth, broad bumps. Hence,
we argue that those components should not be taken as evidence for accretion
disc emission, nor used to infer BH masses. Finally, we speculate that bright
ULXs could be in a spectral state similar to (or an extension of) the
steep-power-law state of Galactic BH candidates, in which the disc is now
completely comptonized and not directly detectable, and the power-law emission
may be modified by the surrounding, fast-moving, ionized gas.


title:
Tomographic simulations of accretion disks in Cataclysmic Variables -
  flickering and wind

abstract:
  Cataclysmic Variables (CVs) are close binary systems where mass is
transferred from a red dwarf star to a white dwarf star via an accretion disk.
The flickering is observed as stochastic variations in the emitted radiation
both in the continuum and in the emission line profiles. The main goal of our
simulations is to compare synthetic Doppler maps with observed ones, aiming to
constrain the flickering properties and wind parameters. A code was developed
which generates synthetic emission line profiles of a geometrically thin and
optically thick accretion disk. The simulation allows us to include flares in a
particular disk region. The emission line flares may be integrated over
arbitrary ``exposure'' times, producing the synthetic line profiles. Flickering
Doppler maps are created using such synthetic time series. The presence of a
wind inside the Roche lobe was also implemented. Radiative transfer effects in
the lines where taken into account in order to reproduce the single peaked line
profiles frequently seen in nova-like CVs.


title: [TiII] and [NiII] emission from the strontium filament of eta Carinae

abstract:
  We study the nature of the [TiII] and [NiII] emission from the so-called
strontium filament found in the ejecta of eta Carinae. To this purpose we
employ multilevel models of the TiII and NiII systems which are used to
investigate the physical condition of the filament and the excitation
mechanisms of the observed lines. For the TiII ion, for which no atomic data
was previously available, we carry out ab initio calculations of radiative
transition rates and electron impact excitation rate coefficients. It is found
that the observed spectrum is consistent with the lines being excited in a
mostly neutral region with an electron density of the order of $10^7$ cm$^{-3}$
and a temperature around 6000 K. In analyzing three observations with different
slit orientations recorded between March~2000 and November~2001 we find line
ratios that change among various observations, in a way consistent with changes
of up to an order of magnitude in the strength of the continuum radiation
field. These changes result from different samplings of the extended filament,
due to the different slit orientations used for each observation, and yield
clues on the spatial extent and optical depth of the filament. The observed
emission indicates a large Ti/Ni abundance ratio relative to solar abundances.
It is suggested that the observed high Ti/Ni ratio in gas is caused by dust-gas
fractionation processes and does not reflect the absolute Ti/Ni ratio in the
ejecta of \etacar. We study the condensation chemistry of Ti, Ni and Fe within
the filament and suggest that the observed gas phase overabundance of Ti


title: On the First Generation of Stars

abstract:
  We argue that the first stars may have spanned the conventional mass range
rather than be identified with the Very Massive Objects (100-1000 solar masses)
favoured by numerical simulations. Specifically, we find that magnetic field
generation processes acting in the first protostellar systems suffice to
produce fields that exceed the threshold for MRI instability to operate and
thereby allow the MRI dynamo to generate equipartition-amplitude magnetic
fields on protostellar mass scales below 50 solar masses. Such fields allow
primordial star formation to occur at essentially any metallicity by regulating
angular momentum transfer, fragmentation, accretion and feedback in much the
same way as occurs in conventional molecular clouds.


title: Slow Star Formation in Dense Gas: Evidence and Implications

abstract:
  It has been known for more than 30 years that star formation in giant
molecular clouds (GMCs) is slow, in the sense that only ~1% of the gas forms
stars every free-fall time. This result is entirely independent of any
particular model of molecular cloud lifetime or evolution. Here we survey
observational data on higher density objects in the interstellar medium,
including infrared dark clouds and dense molecular clumps, to determine if
these objects form stars slowly like GMCs, or rapidly, converting a significant
fraction of their mass into stars in one free-fall time. We find no evidence
for a transition from slow to rapid star formation in structures covering three
orders of magnitude in density. This has important implications for models of
star formation, since competing models make differing predictions for the
characteristic density at which star formation should transition from slow to
rapid. The data are inconsistent with models that predict that star clusters
form rapidly and in free-fall collapse. Magnetic- and turbulence-regulated star
formation models can reproduce the observations qualitatively, and the
turbulence-regulated star formation model of Krumholz & McKee quantitatively
reproduces the infrared-HCN luminosity correlation recently reported by Gao &
Solomon. Slow star formation also implies that the process of star cluster
formation cannot be one of global collapse, but must instead proceed over many
free-fall times. This suggests that turbulence in star-forming clumps must be
driven, and that the competitive accretion mechanism does not operate in
typical cluster-forming molecular clumps.


title:
The Robinson Gravitational Wave Background Telescope (BICEP): a
  bolometric large angular scale CMB polarimeter

abstract:
  The Robinson Telescope (BICEP) is a ground-based millimeter-wave bolometric
array designed to study the polarization of the cosmic microwave background
radiation (CMB) and galactic foreground emission. Such measurements probe the
energy scale of the inflationary epoch, tighten constraints on cosmological
parameters, and verify our current understanding of CMB physics. Robinson
consists of a 250-mm aperture refractive telescope that provides an
instantaneous field-of-view of 17 degrees with angular resolution of 55 and 37
arcminutes at 100 GHz and 150 GHz, respectively. Forty-nine pair of
polarization-sensitive bolometers are cooled to 250 mK using a 4He/3He/3He
sorption fridge system, and coupled to incoming radiation via corrugated feed
horns. The all-refractive optics is cooled to 4 K to minimize polarization
systematics and instrument loading. The fully steerable 3-axis mount is capable
of continuous boresight rotation or azimuth scanning at speeds up to 5 deg/s.
Robinson has begun its first season of observation at the South Pole. Given the
measured performance of the instrument along with the excellent observing
environment, Robinson will measure the E-mode polarization with high
sensitivity, and probe for the B-modes to unprecedented depths. In this paper
we discuss aspects of the instrument design and their scientific motivations,
scanning and operational strategies, and the results of initial testing and
observations.


title:
The First DIRECT Distance Determination to a Detached Eclipsing Binary
  in M33

abstract:
  We present the first direct distance determination to a detached eclipsing
binary in M33, which was found by the DIRECT Project. Located in the OB 66
association at coordinates (alpha, delta)=(01:33:46.17,+30:44:39.9) for
J2000.0, it was one of the most suitable detached eclipsing binaries found by
DIRECT for distance determination, given its apparent magnitude and orbital
period. We obtained follow-up BV time series photometry, JHKs photometry and
optical spectroscopy from which we determined the parameters of the system. It
contains two O7 main sequence stars with masses of 33.4+/-3.5 Mo and 30.0+/-3.3
Mo and radii of 12.3+/-0.4 Ro and 8.8+/-0.3 Ro, respectively. We derive
temperatures of 37000+/-1500 K and 35600+/-1500 K. Using BVRJHKs photometry for
the flux calibration, we obtain a distance modulus of 24.92+/-0.12 mag
(964+/-54 kpc), which is ~0.3 mag longer than the Key Project distance to M33.
We discuss the implications of our result and the importance of establishing
M33 as an independent rung on the cosmological distance ladder.


title:
Recipes for stellar jets: results of combined optical/infrared
  diagnostics

abstract:
  We examine the conditions of the plasma along a sample of 'classical'
Herbig-Haro jets located in the Orion and Vela star forming regions, through
combined optical-infrared spectral diagnostics. Our sample includes HH 111, HH
34, HH 83, HH 73, HH 24 C/E, HH 24 J, observed at moderate spatial/spectral
resolution. The obtained spectra cover a wide wavelength range from 0.6-2.5 um,
including many transitions from regions of different excitation conditions.
This allows us to probe the density and temperature stratification which
characterises the cooling zones behind the shock fronts along the jet. The
derived physical parameters (such as the extinction, the electron density and
temperature, the ionisation fraction, and the total density) are used to
estimate the depletion onto dust grains of Calcium and Iron with respect to
solar abundances. This turns out to be between 70% and 0% for Ca and ~90% for
Fe, suggesting that the weak shocks present in the beams are not capable of
completely destroying the dust grains. We then derive the mass flux rates
(Mdot_jet is on average 5 10^-8 M_solar yr^-1) and the associated linear
momentum fluxes. The latter are higher than, or of the same order as, those
measured in the coaxial molecular flows, suggesting that the flows are jet
driven. Finally, we discuss differences between jets in our sample.


title: Dark Matter Halos with Cores from Hierarchical Structure Formation

abstract:
  We show that dark matter emerging from late decays (z < 1000) produces a
linear power spectrum identical to that of Cold Dark Matter (CDM) on all
observationally relavant scales (> 0.1 Mpc), and simultaneously generates
observable constant-density cores in small dark matter halos. We refer to this
class of models as meta-Cold Dark Matter (mCDM), because it is born with
non-relativistic velocities from the decays of cold thermal relics. The
constant-density cores are a result of the low phase-space density of mCDM at
birth. Warm dark matter cannot produce similar size phase-space limited cores
without saturating the Ly-alpha power spectrum bounds. Dark matter dominated
galaxy rotation curves and stellar velocity dispersion profiles may provide the
best means to discriminate between mCDM and CDM. mCDM candidates are motivated
by the particle spectrum of supersymmetric and extra dimensional extensions to
the standard model of particle physics.


title:
The Interplay between Star Formation and the Nuclear Environment of our
  Galaxy: Deep X-ray Observations of the Galactic Center Arches and Quintuplet
  Clusters

abstract:
  The Galactic center (GC) provides a unique laboratory for a detailed
examination of the interplay between massive star formation and the nuclear
environment of our Galaxy. Here, we present an 100 ks Chandra ACIS observation
of the Arches and Quintuplet star clusters. We also report on a complementary
mapping of the dense molecular gas near the Arches cluster made with the Owens
Valley Millimeter Array. The number-flux relation of point-like X-ray sources
indicates an over-population of relatively bright X-ray sources, which are
apparently associated with the clusters. The sources in the core of the Arches
and Quintuplet clusters are most likely extreme colliding wind massive star
binaries. The diffuse X-ray emission from the core of the Arches cluster has a
spectrum showing a 6.7-keV emission line and a surface intensity profile
declining steeply with radius, indicating an origin in a cluster wind. In the
outer regions near the Arches cluster, the overall diffuse X-ray enhancement
demonstrates a bow shock morphology and is prominent in the Fe Kalpha 6.4-keV
line emission. Much of this enhancement may result from an ongoing collision
between the cluster and the adjacent molecular cloud. The older and less
compact Quintuplet cluster contains much weaker X-ray sources and diffuse
emission, probably originating from low-mass stellar objects as well as a
cluster wind. However, the overall population of these objects, constrained by
the observed total diffuse X-ray luminosities, is substantially smaller than
expected for both clusters. This deficiency of low-mass objects may be a
manifestation of the unique star formation environment of the Galactic center.


title:
Capella Corona Revisited: A Combined View from \textit{XMM-Newton} RGS,
  \textit{Chandra} HETGS, and LETGS

abstract:
  We present a combined analysis of the X-ray emission of the Capella corona
obtained with \textit{XMM-Newton} RGS, \textit{Chandra} HETGS, and LETGS. An
improved atomic line database and a new differential emission measure (DEM)
deconvolution method are developed for this purpose. Our new atomic database is
based on the Astrophysical Plasma Emission Database and incorporates improved
calculations of ionization equilibrium and line emissivities for L-shell ions
of abundant elements using the Flexible Atomic Code. The new DEM deconvolution
method uses a Markov Chain Monte-Carlo (MCMC) technique which differs from
existing MCMC or $\chi^2$-fitting based methods. We analyze the advantages and
disadvantages of each individual instrument in determining the DEM and
elemental abundances. We conclude that results from either RGS or HETGS data
alone are not robust enough due to their failure to constrain DEM in some
temperature region or the lack of significant continuum emission in the
wavelength band of the spectrometers, and that the combination of HETGS and RGS
gives more stringent constraints on the DEM and abundance determinations. Using
the LETGS data, we show that the recently discovered inconsistencies between
the EUV and X-ray lines of Fe XVIII and XIX also exist in more highly charged
iron ions, up to Fe XXIII, and that enhanced interstellar absorption due to
partially ionized plasma along the Capella line of sight may explain some, but
not all, of these discrepancies.


title:
Molecular Line Observations of Infrared Dark Clouds: Seeking the
  Precursors to Intermediate and Massive Star Formation

abstract:
  We have identified 41 infrared dark clouds from the 8 micron maps of the
Midcourse Space Experiment (MSX), selected to be found within one square degree
areas centered on known ultracompact HII regions. We have mapped these infrared
dark clouds in N2H+(1-0), CS(2-1) and C18O(1-0) emission using the Five College
Radio Astronomy Observatory. The maps of the different species often show
striking differences in morphologies, indicating differences in evolutionary
state and/or the presence of undetected, deeply embedded protostars. We derive
an average mass for these clouds using N2H+ column densities of ~2500 solar
masses, a value comparable to that found in previous studies of high mass star
forming cores using other mass tracers. The linewidths of these clouds are
typically ~2.0 - 2.9 km/s. Based on the fact that they are dark at 8 micron,
compact, massive, and have large velocity dispersions, we suggest that these
clouds may be the precursor sites of intermediate and high mass star formation.


title: Near-Horizon Solution for DGP Perturbations

abstract:
  We develop a scaling ansatz for the master equation in Dvali, Gabadadze,
Porrati cosmologies, which allows us to solve the equations of motion for
perturbations off the brane during periods when the on-brane evolution is
scale-free. This allows us to understand the behavior of the gravitational
potentials outside the horizon at high redshifts and close to the horizon
today. We confirm that the results of Koyama and Maartens are valid at scales
relevant for observations such as galaxy-ISW correlation. At larger scales,
there is an additional suppression of the potential which reduces the growth
rate even further and would strengthen the ISW effect.


title: Large-Scale Tests of the DGP Model

abstract:
  The self-accelerating braneworld model (DGP) can be tested from measurements
of the expansion history of the universe and the formation of structure.
Current constraints on the expansion history from supernova luminosity
distances, the CMB, and the Hubble constant exclude the simplest flat DGP model
at about 3sigma. The best-fit open DGP model is, however, only a marginally
poorer fit to the data than flat LCDM. Its substantially different expansion
history raises structure formation challenges for the model. A dark-energy
model with the same expansion history would predict a highly significant
discrepancy with the baryon oscillation measurement due the high Hubble
constant required and a large enhancement of CMB anisotropies at the lowest
multipoles due to the ISW effect. For the DGP model to satisfy these
constraints new gravitational phenomena would have to appear at the non-linear
and cross-over scales respectively. A prediction of the DGP expansion history
in a region where the phenomenology is well understood is that high-redshift
galaxies should be substantially correlated with the CMB through the ISW
effect. This correlation should provide a sharp test of the DGP model in the
future.


title: Scalar-Tensor Models of Normal and Phantom Dark Energy

abstract:
  We consider the viability of dark energy (DE) models in the framework of the
scalar-tensor theory of gravity, including the possibility to have a phantom DE
at small redshifts $z$ as admitted by supernova luminosity-distance data. For
small $z$, the generic solution for these models is constructed in the form of
a power series in $z$ without any approximation. Necessary constraints for DE
to be phantom today and to cross the phantom divide line $p=-\rho$ at small $z$
are presented. Considering the Solar System constraints, we find for the
post-Newtonian parameters that $\gamma_{PN}<1$ and $\gamma_{PN,0}\approx 1$ for
the model to be viable, and $\beta_{PN,0}>1$ (but very close to 1) if the model
has a significantly phantom DE today. However, prospects to establish the
phantom behaviour of DE are much better with cosmological data than with Solar
System experiments. Earlier obtained results for a $\Lambda$-dominated universe
with the vanishing scalar field potential are extended to a more general DE
equation of state confirming that the cosmological evolution of these models
rule them out. Models of currently fantom DE which are viable for small $z$ can
be easily constructed with a constant potential; however, they generically
become singular at some higher $z$. With a growing potential, viable models
exist up to an arbitrary high redshift.


title:
Speckle nulling for exoplanet detection with space-based coronagraphic
  telescopes

abstract:
  To detect Earth-like planets in the visible with a coronagraphic telescope,
two major noise sources have to be overcome: the photon noise of the diffracted
star light, and the speckle noise due to the star light scattered by
instrumental defects. Coronagraphs tackle only the photon noise contribution.
In order to decrease the speckle noise below the planet level, an active
control of the wave front is required. We have developed analytical methods to
measure and correct the speckle noise behind a coronagraph with a deformable
mirror. In this paper, we summarize these methods, present numerical
simulations, and discuss preliminary experimental results obtained with the
High-Contrast Imaging Testbed at NASA's Jet Propulsion Laboratory.


title:
Determinations of temperature and density for solar-like Stars using Si
  XI soft X-ray emission lines

abstract:
  We study temperature and density sensitivities of ratios of Si XI soft X-ray
emission lines, in the wavelength range of 43--54\AA . The typical temperature
of the formation of the analyzed lines is around 1.6~MK, which makes this
analysis complementary to the analysis of He-like triplets being sensitive to
hotter plasma. We present theoretical calculations and compare them with ratios
obtained from high-resolution X-ray spectra of five solar-like stars: Procyon,
$\alpha$ Cen A$&$B, $\epsilon$ Eri, and Capella. We find that our results are
in good agreement with results obtained by other authors through different
diagnostics, namely the analysis of density- and temperature-sensitive He-like
triplet lines. We further estimate the coronal pressure and filling factors
from Si~XI lines in this study.


title: Instruments without optics: an integrated photonic spectrograph

abstract:
  In recent years, a great deal of emphasis has been placed on achieving the
diffraction limit with large aperture telescopes. For a well matched
focal-plane instrument, the diffraction limit provides the highest possible
angular resolution and sensitivity per pixel. But it offers another key
advantage as we now show. Conventionally, as the telescope aperture D grows,
the instrument size grows in proportion to D, and cost increases as D^2 or
faster. However, an instrument that operates at the diffraction limit can break
the trend of spiralling costs. In traditional instruments, the light must pass
through a succession of large lenses, mirrors and gratings, making it difficult
to conserve the integrity of such as small psf. An alternative approach, as we
now show, is to couple the diffraction limited beam directly into an integrated
photonic spectrograph operating in low-order modes.


title: Coupling light into optical fibres near the diffraction limit

abstract:
  The burgeoning field of astrophotonics explores the interface between
astronomy and photonics. Important applications include photonic OH suppression
at near-infrared wavelengths, and integrated photonic spectroscopy. These new
photonic mechanisms are not well matched to conventional multi-mode fibres and
are best fed with single or few-mode fibres. We envisage the largest gains in
astrophotonics will come from instruments that operate with single or few-mode
fibres in the diffraction limited or near diffraction limited regimes. While
astronomical instruments have largely solved the problem of coupling light into
multi-mode fibres this is largely unexplored territory for few-mode and
single-mode fibres. Here we describe a project to explore this topic in detail,
and present initial results on coupling light into single and few-mode fibres
at the diffraction limit. We find that fibres with as few as ~5 guided modes
have qualitatively different behaviour to single-mode fibres and share a number
of the beneficial characteristics of multi-mode fibres.


title: Proto-clusters in the Lambda CDM Universe

abstract:
  We compare the highly clustered populations of very high redshift galaxies
with proto-clusters identified numerically in a standard $\Lambda$CDM universe
($\Omega_0=0.3, \lambda_0=0.7$) simulation. We evolve 256^3 dark matter
particles in a comoving box of side 150h^{-1}Mpc. By the present day there are
63 cluster sized objects of mass in excess of 10^{14}h^{-1}Mo in this box. We
trace these clusters back to higher redshift finding that their progenitors at
z=4--5 are extended regions of typically 20--40 Mpc (comoving) in size, with
dark halos of mass in excess of 10^{12}h^{-1}Mo and are overdense by typically
1.3--13 times the cosmological mean density. Comparison with the observation of
Lyman alpha emitting (LAEs) galaxies at z=4.86 and at z=4.1 indicates that the
observed excess clustering is consistent with that expected for a proto-cluster
region if LAEs typically correspond to massive dark halos of more than
10^{12}h^{-1}Mo. We give a brief discussion on the relation between high
redshift concentration of massive dark halos and present day rich clusters of
galaxies.


title:
Unconstrained Astrometric Orbits for Hipparcos Stars with Stochastic
  Solutions

abstract:
  A considerable number of astrometric binaries whose positions on the sky do
not obey the standard model of mean position, parallax and linear proper
motion, were observed by the Hipparcos satellite. Some of them remain
non-discovered, and their observational data have not been properly processed
with the more adequate astrometric model that includes nonlinear orbital
motion. We develop an automated algorithm based on "genetic optimization", to
solve the orbital fitting problem with no prior information about the orbital
elements is available (from, e.g., spectroscopic data or radial velocity
monitoring). We test this method on Hipparcos stars with known orbital
solutions in the catalog, and further apply it to stars with stochastic
solutions, which may be unresolved binaries. At a confidence level of 99%,
orbital fits are obtained for 65 stars, most of which have not been known as
binary. A few of the new probable binaries with A-type primaries with periods
444-2015 d are chemically peculiar stars, including Ap and \lambda Boo type.
The anomalous spectra of these stars are explained as admixture of the light
from the unresolved, sufficiently bright and massive companions. We estimate
the apparent orbits of four stars which have been identified as members of the
300 Myr-old UMa kinematic group. Another four new nearby binaries may include
low-mass M-type or brown dwarf companions. Similar astrometric models and
algorithms can be used for binary stars and planet hosts observed by SIM
PlanetQuest and Gaia.


title: On the investigations of galaxy redshift periodicity

abstract:
  In this article we present a historical review of study of the redshift
periodicity of galaxies, starting from the first works performed in the
seventies of the twentieth century until the present day. We discuss the
observational data and methods used, showing in which cases the discretization
of redshifts was observed. We conclude that galaxy redshift periodisation is an
effect which can really exist. We also discussed the redshift discretization in
two different structures: the Local Group of galaxies and the Hercules
Supercluster. Contrary to the previous studies we consider all galaxies which
can be regarded as a structure member disregarding the accuracy of velocity
measurements. We applied the power spectrum analysis using the Hann function
for weighting, together with the jackknife error estimator. In both the
structures we found weak effects of redshift periodisation.


title: Advances in infrared and imaging fibres for astronomical instrumentation

abstract:
  Optical fibres have already played a huge part in ground based astronomical
instrumentation, however, with the revolution in photonics currently taking
place new fibre technologies and integrated optical devices are likely to have
a profound impact on the way we manipulate light in the future. The
Anglo-Australian Observatory, along with partners at the Optical Fibre
Technology Centre of the University of Sydney, is investigating some of the
developing technologies as part of our Astrophotonics programme. In this paper
we discuss the advances that have been made with infrared transmitting fibre,
both conventional and microstructured, in particular those based on flouride
glasses. Flouride glasses have a particularly wide transparent region from the
UV through to around 7um, whereas silica fibres, commonly used in astronomy,
only transmit out to about 2um. We discuss the impact of advances in fibre
manufacture that have greatly improved the optical, chemical resistance and
physical properties of the flouride fibres. We also present some encouraging
initial test results for a modern imaging fibre bundle and imaging fibre taper.


title:
Spitzer observations of acetylene bands in carbon-rich AGB stars in the
  Large Magellanic Cloud

abstract:
  We investigate the molecular bands in carbon-rich AGB stars in the Large
Magellanic Cloud (LMC), using the InfraRed Spectrograph (IRS) on board the
Spitzer Space Telescope (SST) over the 5--38 micron range. All 26
low-resolution spectra show acetylene (C2H2) bands at 7 and 14 micron. The
hydrogen cyanide (HCN) bands at these wavelengths are very weak or absent. This
is consistent with low nitrogen abundances in the LMC. The observed 14 micron
C2H2 band is reasonably reproduced by an excitation temperature of 500 K. There
is no clear dilution of the 14 micron band by circumstellar dust emission. This
14 micron band originates from molecular gas in the circumstellar envelope in
these high mass-loss rate stars, in agreement with previous findings for
Galactic stars. The C2H2,column density, derived from the 13.7 micron band,
shows a gas mass-loss rate in the range 3x10^-6 to 5x10^{-5} Msun yr-1. This is
comparable with the total mass-loss rate of these stars estimated from the
spectral energy distribution. Additionally, we compare the line strengths of
the 13.7 micron C2H2 band of our LMC sample with those of a Galactic sample.
Despite the low metallicity of the LMC, there is no clear difference in the
C2H2 abundance among LMC and Galactic stars. This reflects the effect of the
3rd dredge-up bringing self-produced carbon to the surface, leading to high C/O
ratios at low metallicity.


title: On the radio properties of the highest redshift quasars

abstract:
  We present deep radio observations of the most distant complete quasar sample
drawn from the Sloan Digital Sky Survey. Combining our new data with those from
literature we obtain a sample which is ~100 per cent complete down to S_1.4GHz
= 60 \mu Jy over the redshift range 3.8 < z < 5. The fraction of radio
detections is relatively high (~43 per cent), similar to what observed locally
in bright optical surveys. Even though the combined radio and optical
properties of quasars remain overall unchanged from z ~ 5 to the local
Universe, there is some evidence for a slight over-abundance of radio-loud
sources at the highest redshifts when compared with the lower-z regime.
  Exploiting the deep radio VLA observations we present the first attempt to
directly derive the radio luminosity function of bright quasars at z ~ 4. The
unique depth -- both in radio and optical -- allows us to thoroughly explore
the population of optically bright FR~II quasars up to z ~ 5 and opens a window
on the behaviour of the brightest FR~I sources. A close investigation of the
space density of radio loud quasars also suggests a differential evolution,
with the more luminous sources showing a less pronounced cut-off at high z when
compared with the less luminous ones.


title:
Large-scale structure of Lyman break galaxies around a radio galaxy
  protocluster at z~4

abstract:
  We present broad-band imaging with the Subaru Telescope of a 25'x25' field
surrounding the radio galaxy TN J1338-1942 at redshift z=4.1. The field
contains excesses of Lyman-alpha emitters (LAEs) and Lyman break galaxies
(LBGs) identified with a protocluster surrounding the radio galaxy. Our new
wide-field images provide information about the boundary of the protocluster
and its surroundings. There are 874 candidate LBGs within our field, having
redshifts in the range z=3.5-4.5. An examination of the brightest of these
(with i'< 25.0) shows that the most prominent concentration coincides with the
previously discovered protocluster. The diameter of this galaxy overdensity
corresponds to ~2 Mpc at z=4, consistent with the previous estimation using
LAEs. Several other concentrations of LBGs are observed in the field, some of
which may well be physically connected with the z=4.1 protocluster. The
observed structure in the smoothed LBG distribution can be explained as the
projection of large-scale structure, within the redshift range z=3.5-4.5,
comprising compact overdensities and prominent larger voids. If the 5-8
observed compact overdensities are associated with protoclusters, the observed
protocluster volume density is ~5x10^-6 Mpc^-3, similar to the volume density
of rich clusters in the local Universe.


title:
Probing the mass-loss history of AGB and red supergiant stars from CO
  rotational line profiles I. Theoretical model -- Mass-loss history unravelled
  in VY CMa

abstract:
  Context: Mass loss plays a dominant role in the evolution of low mass stars
while they are on the Asymptotic Giant Branch (AGB). The gas and dust ejected
during this phase are a major source in the mass budget of the interstellar
medium. Recent studies have pointed towards the importance of variations in the
mass-loss history of such objects. Aims: By modelling the full line profile of
low excitation CO lines emitted in the circumstellar envelope, we can study the
mass-loss history of AGB stars. Methods: We have developed a non-LTE radiative
transfer code, which calculates the velocity structure and gas kinetic
temperature of the envelope in a self-consistent way. The resulting structure
of the envelope provides the input for the molecular line radiative
calculations which are evaluated in the comoving frame. The code allows for the
implementation of modulations in the mass-loss rate. This code has been
benchmarked against other radiative transfer codes and is shown to perform well
and efficiently. Results: We illustrate the effects of varying mass-loss rates
in case of a superwind phase. The model is applied to the well-studied case of
VY CMa. We show that both the observed integrated line strengths as the
spectral structure present in the observed line profiles, unambiguously
demonstrate that this source underwent a phase of high mass loss (~ 3.2E-4
Msun/yr) some 1000 yr ago. This phase took place for some 100 yr, and was
preceded by a low mass-loss phase (~ 1E-6 Msun/yr) taking some 800 yr. The
current mass-loss rate is estimated to be in the order of 8E-5 Msun/yr.
Conclusions: In this paper, we demonstrate that both the relative strength of
the CO rotational line profiles and the (non)-occurrence of spectral structure
in the profile offer strong diagnostics to pinpoint the mass-loss history.


title: Methanol Maser Polarization in W3(OH)

abstract:
  We present the first 6.7 GHz methanol maser linear polarization map of the
extended filamentary maser structure around the compact HII region W3(OH). The
methanol masers show linear polarization up to 8 per cent and the polarization
angles indicate a magnetic field direction along the North-South maser
structure. The polarization angles are consistent with those measured for the
OH masers, taking into account external Faraday rotation toward W3(OH), and
confirm that the OH and methanol masers are found in similar physical
conditions. Additionally we discuss the Zeeman splitting of the 6.7 GHz
methanol transition and present an upper limit of ~22 mG for the magnetic field
strength in the maser region. The upper limit is fully consistent with the
field strengths derived from OH maser Zeeman splitting.


title: The density profiles of hot galactic halo gas

abstract:
  Extended gas haloes around galaxies are a ubiquitous prediction of galaxy
formation scenarios. However, the density profiles of this hot halo gas is
virtually unknown, although various profiles have been suggested on theoretical
grounds. In order to quantitatively address the gas profile, we compare
galaxies from direct cosmological simulations with analytical solutions of the
underlying gas equations. We find remarkable agreement between simulations and
theoretical predictions. We present an expression for this gas profile with a
non-trivial dependence on the total mass profile. This expression is useful
when setting up equilibrium galaxy models for numerical experiments.


title: Searching for Gas-Rich Disks around T Tauri Stars in Lupus

abstract:
  AIMS : To characterize the molecular environment of classical T Tauri stars
in Lupus observed with the Spitzer Space Telescope and to search for gas-rich
disks toward these sources.
  METHODS : Submillimeter observations of 12CO, 13CO and C18O in the J=3-2 and
2-1 lines were obtained with the James Clerk Maxwell Telescope toward a sample
of 21 T Tauri stars with disks in the Lupus molecular clouds. Pointings at the
sources and at selected off-positions are presented in order to disentangle
material associated with disks from ambient cloud material.
  RESULTS : One source, IM Lup (Sz 82), has been found with double-peaked 12CO
and 13CO profiles characteristic of a large rotating gas disk. The inclination
of the disk is found to be ~20 degrees, with an outer radius of 400-700 AU. For
most other sources, including GQ Lup with its substellar companion, the
single-dish 12CO lines are dominated by extended cloud emission with a complex
velocity structure. No evidence for molecular outflows is found. Compact C18O
emission due to dense circumstellar material has been detected toward only two
sources. Future searches for gas-rich disks in Lupus should either use
interferometers or perform very deep single-dish integrations in dense gas
tracers to separate the cloud and disk emission.


title:
Timescales of merger, starburst and AGN activity in radio galaxy B2
  0648+27

abstract:
  In this paper we use neutral hydrogen HI and optical spectroscopic
observations to compare the timescales of a merger event, starburst episode and
radio-AGN activity in the radio galaxy B2 0648+27. We detect a large ring-like
structure of HI in emission around the early-type host galaxy of B2 0648+27
(M_HI = 8.5 x 10^9 Msun, diameter = 190 kpc). We interpret this as the result
of a major merger that occurred > 1.5 Gyr ago. From modelling optical long-slit
spectra we find that a young stellar population of 0.3 Gyr, indicative of a
past starburst event, dominates the stellar light throughout the galaxy. The
off-set in time between the merger event and the starburst activity in B2
0648+27 suggests that the starburst was triggered in an advanced stage of the
merger, which can be explained if the gas-rich progenitor galaxies contained a
bulge. Although the exact age of the radio source remains uncertain, there
appears to be a significant time-delay between the merger/starburst event and
the current episode of radio-AGN activity. We also observe an outflow of
emission-line gas in this system, which is likely related to superwinds driven
by the stars that formed during the starburst event. We argue that the radio
galaxy B2 0648+27 is a link in the evolutionary sequence between Ultra-Luminous
Infrared Galaxies (ULIRGs) and genuine early-type galaxies.


title:
The co-evolution of the obscured quasar PKS1549-79 and its host galaxy:
  evidence for a high accretion rate and warm outflow

abstract:
  ABRIDGED: We use deep optical, IR and radio observations to explore the
symbiosis between the nuclear activity and galaxy evolution in the southern
compact radio source PKS1549-79 (z=0.1523). The optical imaging observations
reveal the presence of tidal tail features which provide strong evidence that
the host galaxy has undergone a major merger in the recent past. This is
further supported by the detection of a young stellar population which was
formed 50-250Myr ago and makes up 1-30% of the total stellar mass. Despite the
core-jet structure of the radio source we detect HI absorption associated with
both the core and the jet. The luminous, quasar-like AGN (M_V < -23.5) is
highly extinguished (A_v > 4.9) at optical wavelengths and shows many
properties in common with narrow line Seyfert 1 galaxies (NLS1), including
relatively narrow permitted lines (FWHM ~ 1940 km/s), highly blueshifted [OIII]
lines (~680 km/s), and evidence that the putative supermassive black hole is
accreting at a high Eddington ratio. This suggests that accretion at high
Eddington ratio does not prevent the formation of powerful jets. Our
observations lend strong support to the predictions of some recent numerical
simulations of galaxy mergers in which the black hole grows rapidly through
merger-induced accretion following the coalescence of the nuclei of two merging
galaxies; the major growth phase largely hidden by the natal gas and dust.
Although the models predict that AGN-driven outflows will eventually remove the
gas from the bulge of the host galaxy, the visible warm outflow in PKS1549-79
is not currently capable of doing so. ABRIDGED


title:
Integral field spectroscopy of H-alpha emission in cooling flow cluster
  cores: disturbing the molecular gas reservoir

abstract:
  We present optical integral field spectroscopy of the H-alpha-luminous (>1E42
erg/s) central cluster galaxies in the cores of the cooling flows A1664, A1835,
A2204 and Zw8193. From the [NII]+H-alpha complex we derive 2-D views of the
distribution and kinematics of the emission line gas, and further diagnostics
from the [SII] and [OI] lines. The H-alpha emission shows a variety of
disturbed morphologies with velocity gradients and splittings of several
hundred km/s on scales of 20 kpc or more. Despite the small sample size, there
are some generic features. The most disturbed H-alpha emission appears to be
associated with secondary galaxies within 10-20 kpc (projected) of the central
galaxy and close in velocity to the H-alpha. The global H-alpha kinematics
match those of CO(1-0) emission in single-dish data. The [NII]/H-alpha,
[SII]/H-alpha and [OI]/H-alpha ratios vary little with position, local H-alpha
surface brightness or between clusters. We propose that the H-alpha and CO
emission arise in molecular clouds heated by a starburst which has been
triggered by interaction with a secondary galaxy. Such CO emission is known to
trace massive (>1E10 M_sun) compact (<20 kpc) reservoirs of cool molecular gas,
which an infalling galaxy may disturb, distorting the H-alpha morphology and
initiating widespread star formation. We suggest that cloud-cloud collisions in
the undisturbed molecular gas reservoir might be an important excitation source
for the emission line gas in the cores of lower H-alpha luminosity cluster
cores with less intense star formation (abridged).


title: The SUGRA Quintessence Model Coupled to the MSSM

abstract:
  We study the cosmological evolution of the universe when quintessence is
modeled within supergravity, supersymmetry is broken in a hidden sector, and we
also include observable matter in a third independent sector. We find that the
presence of hidden sector supersymmetry breaking leads to modifications of the
quintessence potential. We focus on the coupling of the SUGRA quintessence
model to the MSSM and investigate two possibilities. First one can preserve the
form of the SUGRA potential provided the hidden sector dynamics is tuned. The
currently available limits on the violations of the equivalence principle imply
a universal bound on the vacuum expectation value of the quintessence field
now, \kappa ^{1/2}Q\ll 1. On the other hand, the hidden sector fields may be
stabilised leading to a minimum of the quintessence potential where the
quintessence field acquires a mass of the order of the gravitino mass, large
enough to circumvent possible gravitational problems. However, the cosmological
evolution of the quintessence field is affected by the presence of the minimum
of the potential. The quintessence field settles down at the bottom of the
potential very early in the history of the universe. Both at the background and
the perturbation levels, the subsequent effect of the quintessence field is
undistinguishable from a pure cosmological constant


title:
Unveiling the nature of the highly absorbed X-ray source SAXJ1748.2-2808
  with XMM-Newton

abstract:
  We report on the results of an EPIC XMM-Newton observation of the faint
source SAXJ1748.2-2808 and the surrounding field. This source was discovered
during the BeppoSAX Galactic center survey performed in 1997-1998. A spatial
analysis resulted in the detection of 31 sources within the EPIC field of view.
SAXJ1748.2-2808 is clearly resolved into 2 sources in EPIC images with the
brighter contributing almost 80% of the 2-10keV flux. Spectral fits to this
main source are consistent with an absorbed power-law with a photon index of
1.4+/-0.5 and absorption equivalent to 14E22cm-2 together with an iron line at
6.6+/-0.2 keV with an equivalent width of ~780eV. The significantly better
statistics of the XMM-Newton observation, compared with BeppoSAX,allows to
exclude a thermal nature for the X-ray emission. A comparison with other
observations of SAXJ1748.2-2808 does not reveal any evidence for spectral or
intensity long-term variability. Based on these properties we propose that the
source is a low-luminosity high-mass X-ray binary located in the Galactic
center region.


title: Neutron star masses: dwarfs, giants and neighbors

abstract:
  We discuss three topics related to the neutron star (NS) mass spectrum. At
first we discuss the possibility to form low-mass ($ M \stackrel{<}{\sim} 1
M_{\odot}$) and suggest this is possible only due to fragmentation of rapidly
rotating proto-NSs. Such low-mass NSs should have very high spatial velocities
which could allow identification. A critical assessment of this scenario is
given. Secondly, we discuss mass growth due to accretion for NSs in close
binary systems. With the help of numerical population synthesis calculations we
derive the mass spectrum of massive ($M > 1.8 M_{\odot}$) NSs. Finally, we
discuss the role of the mass spectrum in population studies of young cooling
NSs. We formulate a kind of {\it mass constraint} which can be helpful, in our
opinion, in discussing different competive models of the thermal evolution of
NSs.


title:
VLT/ISAAC Spectra of the H-beta Region in Intermediate-Redshift Quasars
  II. Black Hole Mass and Eddington Ratio

abstract:
  We derive black hole masses for a sample of about 300 AGNs in the redshift
range 0 < z < 2.5. We use the same virial velocity measure (FWHM Hbeta broad
component) for all sources which represents a significant improvement over
previous studies. We review methods and caveats for determining AGN black hole
masses via the virial assumption for motions in the gas producing low
ionization broad emission lines. We derive a corrected FWHM measure for the
broad component of H-beta that better estimates the virialized line emitting
component by comparing our FWHM measures with a sample of reverberated sources
with H-beta radial velocity dispersion measures. We also consider the FWHM of
the FeII 4570 blend as a potential alternative velocity estimator. We find a
range of black hole mass between log M ~ 6 - 10, where the black hole mass M is
in solar masses. Estimates using corrected FWHM, as well as FWHM(Fe II)
measures, reduce the number of sources with log M > 9.5 and suggest that
extremely large M values (log M >~ 10) may not be realistic. Derived Eddington
ratio values values show no evidence for a significant population of
super-Eddington radiators especially after correction is made for sources with
extreme orientation to our line of sight. Sources with FWHM(Hbeta broad
component) <~ 4000 km/s show systematically higher Eddington ratio and lower M
values than broader lined AGNs (including almost all radio-loud sources).


title: Seismic signatures of strange stars with crust

abstract:
  We study acoustic oscillations (eigenfrequencies, velocity distributions,
damping times) of normal crusts of strange stars. These oscillations are very
specific because of huge density jump at the interface between the normal crust
and the strange matter core. The oscillation problem is shown to be
self-similar. For a low (but non-zero) multipolarity l the fundamental mode
(without radial nodes) has a frequency ~300 Hz and mostly horizontal
oscillation velocity; other pressure modes have frequencies >=20 kHz and almost
radial oscillation velocities. The latter modes are similar to radial
oscillations (have approximately the same frequencies and radial velocity
profiles). The oscillation spectrum of strange stars with crust differs from
the spectrum of neutron stars. If detected, acoustic oscillations would allow
one to discriminate between strange stars with crust and neutron stars and
constrain the mass and radius of the star.


title:
Discovery of the two wings of the Kookaburra complex in VHE gamma -rays
  with H.E.S.S

abstract:
  Aims. Search for Very High Energy gamma-ray emission in the Kookaburra
complex through observations with the H.E.S.S. array. Methods. Stereoscopic
imaging of Cherenkov light emission of the gamma-ray showers in the atmosphere
is used for the reconstruction and selection of the events to search for
gamma-ray signals. Their spectrum is derived by a forward-folding maximum
likelihood fit. Results. Two extended gamma-ray sources with an angular (68%)
radius of 3.3-3.4' are discovered at high (>13sigma) statistical significance:
HESS J1420-607 and HESS J1418-609. They exhibit a flux above 1 TeV of
(2.97+/-0.18stat +/-0.60sys)x10-12 and (2.17+/-0.17stat +/-0.43sys)x10-12 cm-2
s-1, respectively, and similar hard photon indices ~2.2. Multi-wavelength
comparisons show spatial coincidence with the wings of the Kookaburra. Two
pulsar wind nebulae candidates, K3/PSR J1420-6048 and the Rabbit, lie on the
edge of the H.E.S.S. sources. Conclusions. The two new sources confirm the
non-thermal nature of at least parts of the two radio wings which overlap with
the gamma-ray emission and establish their connection with the two X-ray pulsar
wind nebulae candidates. Given the large point spread function of EGRET, the
unidentified source(s) 3EG J1420-6038/GeV J1417-6100 could possibly be related
to either or both H.E.S.S. sources. The most likely explanation for the Very
High Energy gamma-rays discovered by H.E.S.S. is inverse Compton emission of
accelerated electrons on the Cosmic Microwave Background near the two candidate
pulsar wind nebulae, K3/PSR J1420-6048 and the Rabbit. Two scenarios which
could lead to the observed large (~10 pc) offset-nebula type morphologies are
briefly discussed.


title:
A Comptonization Model for the Prompt Optical and Infrared Emission of
  GRB 041219A

abstract:
  Prompt optical emission from the $\gamma$-ray burst of GRB 041219A has been
reported by Vestrand et al. There was a fast rise of optical emission
simultaneous with the dominant $\gamma$-ray pulse, and a tight correlation with
the prompt $\gamma$-ray emission has been displayed. These indicate that the
prompt optical emission and $\gamma$-ray emission would naturally have a common
origin. We propose that this optical component can be modeled by considering
the Comptonization of $\gamma$-ray photons by an electron cloud. As a result of
this mechanism, the arrival time of the optical photons is delayed compared
with that of the $\gamma$-rays. We restrict that the lag time to be shorter
than 10 s, within which the prompt optical emission is considered to vary
simultaneously with the prompt $\gamma$-ray emission. Taking the observations
of GRB 041219A into account, we derive the number density of the surrounding
electron cloud required for Comptonization. The redshift of GRB 041219A is
predicted to be $z\lesssim 0.073$ as well.


title:
XMM-Newton observations of the supernova remnant IC443: I. soft X-ray
  emission from shocked interstellar medium

abstract:
  The shocked interstellar medium around IC443 produces strong X-ray emission
in the soft energy band (E<1.5 keV). We present an analysis of such emission as
observed with the EPIC MOS cameras on board the XMM-Newotn observatory, with
the purpose to find clear signatures of the interactions with the interstellar
medium (ISM) in the X-ray band, which may complement results obtained in other
wavelenghts. We found that the giant molecular cloud mapped in CO emission is
located in the foreground and gives an evident signature in the absorption of
X-rays. This cloud may have a torus shape and the part of torus interacting
with the IC443 shock gives rise to 2MASS-K emission in the southeast. The
measured density of emitting X-ray shocked plasma increases toward the
northeastern limb, where the remnant is interacting with an atomic cloud. We
found an excellent correlation between emission in the 0.3-0.5 keV band and
bright optical/radio filament on large spatial scales. The partial shell
structure seen in this band therefore traces the encounter with the atomic
cloud.


title:
Small Magellanic Cloud Be stars: colour-magnitude relations and
  mass-loss

abstract:
  We present an analysis of optical lightcurves of Small Magellanic Cloud
Be-type stars. Observations show that (1) optical excess flux is correlated
with near-IR excess flux indicating a similar mechanism and (2) the lightcurves
can trace out ``loops'' in a colour-magnitude diagram. A simple model for the
time dependent bound-free and free-free emission produced by an outflowing
circumstellar disk gives reasonable fits to the observations.