title: Rapid Star Formation in the Presence of Active Galactic Nuclei

abstract:
  Recent observations reveal galaxies in the early Universe (2<z<6.4) with
large reservoirs of molecular gas and extreme star formation rates. For a very
large range of sources, a tight relationship exists between star formation rate
and the luminosity of the HCN J=1-0 spectral line, but sources at redshifts of
z~2 and beyond do not follow this trend. The deficit in HCN is conventionally
explained by an excess of infrared (IR) radiation due to active galactic nuclei
(AGN). We show in this letter not only that the presence of AGN cannot account
for the excess of IR over molecular luminosity, but also that the observed
abundance of HCN is in fact consistent with a population of stars forming from
near-primordial gas.


title:
Spitzer Quasar and ULIRG evolution study (QUEST): I. The origin of the
  far infrared continuum of QSOs

abstract:
  This paper addresses the origin of the far-infrared (FIR) continuum of QSOs,
based on the Quasar and ULIRG Evolution Study (QUEST) of nearby QSOs and ULIRGs
using observations with the Spitzer Space Telescope. For 27 Palomar-Green QSOs
at z <~ 0.3, we derive luminosities of diagnostic lines ([NeII]12.8um,
[NeV]14.3um, [OIV]25.9um) and emission features (PAH7.7um emission which is
related to star formation), as well as continuum luminosities over a range of
mid- to far-infrared wavelengths between 6 and 60um. We detect star-formation
related PAH emission in 11/26 QSOs and fine-structure line emission in all of
them, often in multiple lines. The detection of PAHs in the average spectrum of
sources which lack individual PAH detections provides further evidence for the
widespread presence of PAHs in QSOs. Similar PAH/FIR and [NeII]/FIR ratios are
found in QSOs and in starburst-dominated ULIRGs and lower luminosity
starbursts. We conclude that the typical QSO in our sample has at least 30% but
likely most of the far-infrared luminosity (~ 10^(10...12)Lsun) arising from
star formation, with a tendency for larger star formation contribution at the
largest FIR luminosities. In the QSO sample, we find correlations between most
of the quantities studied including combinations of AGN tracers and starburst
tracers. The common scaling of AGN and starburst luminosities (and fluxes) is
evidence for a starburst-AGN connection in luminous AGN. Strong correlations of
far-infrared continuum and starburst related quantities (PAH, low excitation
[NeII]) offer additional support for the starburst origin of far-infrared
emission.


title:
Supermassive black hole formation during the assembly of pre-galactic
  discs

abstract:
  In this paper we discuss the evolution of gravitationally unstable
pre-galactic discs that result from the collapse of haloes at high redshift $z
\approx 10$ or so, which have not yet been enriched by metals. In cases where
molecular hydrogen formation is suppressed the discs are maintained at a
temperature of a few thousand degrees Kelvin. However, when molecular hydrogen
is present cooling can proceed down to a few hundred degrees Kelvin. Analogous
to the case of the larger scale proto-galactic discs, we assume that the
evolution of these discs is mainly driven by angular momentum redistribution
induced by the development of gravitational instabilities in the disc. We also
properly take into account the possibility of disc fragmentation. We thus show
that this simple model naturally predicts the formation of supermassive black
holes in the nuclei of such discs and provides a robust determination of their
mass distribution as a function of halo properties. We estimate that roughly 5%
of discs resulting from the collapse of haloes with $M\approx 10^7 M_{\odot}$
should host a massive black hole with a mass $M_{\rm BH}\approx 10^5
M_{\odot}$. We confirm our arguments with time-dependent calculations of the
evolution of the surface density and of the accretion rate in these primordial
discs. This mechanism offers an efficient way to form seed black holes at high
redshift. The predicted masses for our black hole seeds enable the comfortable
assembly of $10^9 M_{\odot}$ black holes powering the luminous quasars detected
by the Sloan Digital Sky Survey at $z = 6$ for a concordance cosmology.
(abridged)


title:
3D photoionisation and dust RT modelling with MOCASSIN: geometry effects
  on the emission line spectra of star-forming regions

abstract:
  Emission line spectra from HII regions are often used to study properties of
the gas in star-forming regions, as well as temperatures and luminosities of
the ionising sources. Empirical diagnostics for the interpretation of
observational data must often be calibrated with the aid of photoionisation
models. Most studies so far have been carried out by assuming spherical or
plane-parallel geometries, with major limitations on allowed gas and dust
density distributions and with the spatial distribution of multiple,
non-centrally-located ionising sources not being accounted for. We present the
first results of our theoretical study of geometric effects, via the
construction of a number of 3D photoionisation models using the MOCASSIN code
for a variety of spatial configurations and ionisation sources. We compare
integrated emission line spectra from such configurations and show evidence of
systematic errors caused by the simplifying assumption of a single, central
location for all ionising sources.


title:
Detection of VHE radiation from the BL Lac PG 1553+113 with the MAGIC
  telescope

abstract:
  In 2005 and 2006, the MAGIC telescope has observed very high energy gamma-ray
emission from the distant BL Lac object PG 1553+113. The overall significance
of the signal is 8.8 sigma for 18.8h observation time. The light curve shows no
significant flux variations on a daily time-scale, the flux level during 2005
was, however, significantly higher compared to 2006. The differential energy
spectrum between ~90 GeV and 500 GeV is well described by a power law with
photon index Gamma = 4.2 +- 0.3. The combined 2005 and 2006 energy spectrum
provides an upper limit of z=0.74 on the redshift of the object.


title: XMM-Newton Detection of the Rare FR II BAL Quasar FIRST J101614.3+520916

abstract:
  We have detected FIRST J101614.3+520916 with the XMM-Newton X-ray
Observatory. FIRST J101614.3+520916, one of the most extreme radio-loud, broad
absorption line (BAL) quasars so far discovered, is also a Fanaroff-Riley type
II (FR II) radio source. We find that, compared to its estimated intrinsic
X-ray flux, the observed X-rays are likely suppressed, and that the observed
hardness ratio indicates significant soft X-ray photons. This is inconsistent
with the simplest model, a normal quasar spectrum absorbed by a large neutral
HI column density, which would primarily absorb the softer photons. More
complex models, involving partial covering, an ionized absorber, ionized mirror
reflection, or jet contributions need to be invoked to explain this source. The
suppressed but soft X-ray emission in this radio-loud BAL quasar is consistent
with the behavior displayed by other BAL quasars, both radio-loud and
radio-quiet.


title: The distribution of ND2H in LDN1689N

abstract:
  Finding tracers of the innermost regions of prestellar cores is important for
understanding their chemical and dynamical evolution before the onset of
gravitational collapse. While classical molecular tracers, such as CO and CS,
have been shown to be strongly depleted in cold, dense gas by condensation on
grain mantles, it has been a subject of discussion to what extent
nitrogen-bearing species, such as ammonia, are affected by this process. As
deuterium fractionation is efficient in cold, dense gas, deuterated species are
excellent tracers of prestellar cores. A comparison of the spatial distribution
of neutral and ionized deuterated species with the dust continuum emission can
thus provide important insights into the physical and chemical structure of
such regions. We study the spatial distribution of the ground-state 335.5 GHz
line of ND2H in LDN1689N, using APEX, and compare it with the distribution of
the DCO+(3--2) line, as well as the 350 micron dust continuum emission observed
with the SHARC~II bolometer camera at CSO. While the distribution of the ND2H
emission in LDN1689N is generally similar to that of the 350 microns dust
continuum emission, the peak of the ND2H emission is offset by ~10'' to the
East from the dust continuum and DCO+ emission peak. ND2H and ND3 share the
same spatial distribution. The observed offset between the ND2H and DCO+
emission is consistent with the hypothesis that the deuterium peak in LDN1689N
is an interaction region between the outflow shock from IRAS16293--2422 and the
dense ambient gas. We detect the J = 4 - 3 line of H13CO+ at 346.998 GHz in the
image side band serendipitously. This line shows the same spatial distribution
as DCO+(3--2), and peaks close to the 350 mic emission maximum which provides
further support for the shock interaction scenario.


title: Evidence for Differential Rotation on a T Tauri Star

abstract:
  Five years of photometric monitoring of the T Tauri star HBC 338 in NGC 1333
has revealed that it is a periodic variable, but the period has changed
significantly with time. From 2000-2003, a period near 5.6 days was observed,
while in the last two seasons, the dominant period is near 4.6 days. No other T
Tauri star has been seen to change its period by such a large percentage. We
propose a model in which a differentially rotating star is seen nearly
equator-on and a high latitude spot has gradually been replaced by a low
latitude spot. We show that this model provides an excellent fit to the
observed shapes of the light curves at each epoch. The amplitude and sense of
the inferred differential rotation is similar to what is seen on the Sun. This
may be surprising given the likely high degree of magnetic surface activity on
the star relative to the Sun but we note that HBC 338 is clearly an exceptional
T Tauri star.


title: The Dwarf Galaxy Population in Nearby Groups. The data

abstract:
  We used V and I CCD photometry to search for low-surface brightness dwarf
galaxies (LSBD) in the central (<0.5 h^-1 Mpc) region of the groups NGC 6868,
NGC 5846, HCG 42 and the poor cluster IC 4765. Using the parameters given by
the exponential profile fit, we identified 80 LSBD candidates with magnitudes
17 < V < 22 mag and with colors V-I < 1.5 mag at the limiting isophote of 25.8
V mag/arcsec^2. The galaxies have mu0 > 22.5 V mag/arcsec^2, h > 1.5 arcsec,
and diameters larger than 1.2 h^-1 kpc. Twenty of the eighty galaxies are
extended LSB galaxies that were detected only on smoothed images, after masking
all high surface brightness objects. The completeness in the detection is ~80%
for galaxies with V<=20 and 22.5<mu0<24.5 V mag/arcsec^2, and below 50% at
fainter magnitudes and central surface brightnesses. In this last bin, the
completeness increases to ~80% when we search for galaxies in smoothed images
instead. The detected LSBD galaxies are highly concentrated towards the center
of the four groups in the inner 250 h^-1 kpc. The best fit power-law slope of
the surface density distribution is, on average, beta ~ -1.5 (R < 250 h^-1
kpc), in agreement with the values found for satellites dwarfs around isolated
E/S0 galaxies and in X-ray groups. The LSBD galaxies in the Mv-mu0 plane does
not show a clear correlation, suggesting that the correlation noted by other
studies could be produced by selection effects. The LSBD dwarf galaxies follow
a well defined color-magnitude relation, extending for more than ten magnitudes
(from bright ellipticals to faint dwarfs). A similar well defined
color-magnitude relation from giants to dwarfs is known to be valid for galaxy
clusters but it is the first time that it is demonstrated in the sparse
environments of groups. (Abridge)


title:
Probing long-period companions to planetary hosts. VLT and CFHT near
  infrared coronographic imaging surveys

abstract:
  We present the results of a deep imaging survey of stars surrounded by
planets detected with the radial velocity technique. The purpose is to search
for and to characterize long-period stellar and substellar companions. The
sample contains a total of 26 stars, among which 6 exhibit additional radial
velocity drifts. We used NACO, at the ESO Very Large Telescope, and PUEO-KIR,
at the Candian French Hawaiian Telescope, to conduct a near-infrared
coronographic survey with adaptive optics of the faint circumstellar
environment of the planetary hosts. The domain investigated ranges between 0.1
to 15" (i.e. about 3 to 500 AU, according to the mean distance of the sample).
The survey is sensitive to companions within the stellar and the substellar
domains, depending on the distance to the central stars and on the star
properties. The images of 14 stars do not reveal any companions once the field
objects are removed. 8 stars have close potential companions that need to be
re-observed within 1-2 years to check for physical companionship. 4 stars are
surrounded by faint objects which are confirmed or very probable companions.
The companion to HD13445 (Gliese 86) is already known. The HD196885 star is a
new close visual binary system with a high probability of being bound. The 2
newly discovered companions, HD1237 B and HD27442 B, share common proper
motions with the central stars. Orbital motion is detected for HD1237 B. HD1237
B is likely a low-mass M star, located at 70 AU (projected distance) from the
primary. HD27442 B is most probably a white dwarf companion located at about
240 AU (projected distance).


title: New constrains on Gliese 86 B

abstract:
  We present the results of multi epochs imaging observations of the companion
to the planetary host Gliese 86. Associated to radial velocity measurements,
this study aimed at characterizing dynamically the orbital properties and the
mass of this companion (here after Gliese 86 B), but also at investigating the
possible history of this particular system. We used the adaptive optics
instrument NACO at the ESO Very Large Telescope to obtain deep coronographic
imaging in order to determine new photometric and astrometric measurements of
Gliese 86 B. Part of the orbit is resolved. The photometry of Gliese B
indicates colors compatible with a ~70 Jupiter mass brown dwarf or a white
dwarf. Both types of objects allow to fit the available, still limited
astrometric data. Besides, if we attribute the long term radial velocity
residual drift observed for Gliese A to B, then the mass of the latter object
is ~0.5 Msun. We analyse both astrometric and radial velocity data to propose
first orbital parameters for Gliese B. Assuming Gliese B is a ~0.5 Msun white
dwarf, we explore the constraints induced by this hypothesis and refine the
parameters of the system.


title: Near Scale Invariance with Modified Dispersion Relations

abstract:
  We describe a novel mechanism to seed a nearly scale invariant spectrum of
adiabatic perturbations during a non-inflationary stage. It relies on a
modified dispersion relation that contains higher powers of the spatial
momentum of matter perturbations. We implement this idea in the context of a
massless scalar field in an otherwise perfectly homogeneous universe. The
couplings of the field to background scalars and tensors give rise to the
required modification of its dispersion relation, and the couplings of the
scalar to matter result in an adiabatic primordial spectrum. This work is meant
to explicitly illustrate that it is possible to seed nearly scale invariant
primordial spectra without inflation, within a conventional expansion history.


title:
Formation of Globular Clusters in Hierarchical Cosmology: ART and
  Science

abstract:
  We test the hypothesis that globular clusters form in supergiant molecular
clouds within high-redshift galaxies. Numerical simulations demonstrate that
such large, dense, and cold gas clouds assemble naturally in current
hierarchical models of galaxy formation. These clouds are enriched with heavy
elements from earlier stars and could produce star clusters in a similar way to
nearby molecular clouds. The masses and sizes of the model clusters are in
excellent agreement with the observations of young massive clusters. Do these
model clusters evolve into globular clusters that we see in our and external
galaxies? In order to study their dynamical evolution, we calculate the orbits
of model clusters using the outputs of the cosmological simulation of a Milky
Way-sized galaxy. We find that at present the orbits are isotropic in the inner
50 kpc of the Galaxy and preferentially radial at larger distances. All
clusters located outside 10 kpc from the center formed in the now-disrupted
satellite galaxies. The spatial distribution of model clusters is spheroidal,
with a power-law density profile consistent with observations. The combination
of two-body scattering, tidal shocks, and stellar evolution results in the
evolution of the cluster mass function from an initial power law to the
observed log-normal distribution. However, not all initial conditions and not
all evolution scenarios are consistent with the observed mass function.


title:
K-corrections and filter transformations in the ultraviolet, optical,
  and near infrared

abstract:
  Template fits to observed galaxy fluxes allow calculation of K-corrections
and conversions among observations of galaxies at various wavelengths. We
present a method for creating model-based template sets given a set of
heterogeneous photometric and spectroscopic galaxy data. Our technique,
non-negative matrix factorization, is akin to principle component analysis
(PCA), except that it is constrained to produce nonnegative templates, it can
use a basis set of models (rather than the delta function basis of PCA), and it
naturally handles uncertainties, missing data, and heterogeneous data
(including broad-band fluxes at various redshifts). The particular
implementation we present here is suitable for ultraviolet, optical, and
near-infrared observations in the redshift range 0 < z < 1.5. Since we base our
templates on stellar population synthesis models, the results are intepretable
in terms of approximate stellar masses and star-formation histories. We present
templates fit with this method to data from GALEX, Sloan Digital Sky Survey
spectroscopy and photometry, the Two-Micron All Sky Survey, the Deep
Extragalactic Evolutionary Probe and the Great Observatories Origins Deep
Survey. In addition, we present software for using such data to estimate
K-corrections and stellar masses.


title:
Constraining a double component dark energy model using type Ia
  supernovae data

abstract:
  A two-component fluid representing dark energy is studied. One of the
components has a polytropic form, while the other has a barotropic form. Exact
solutions are obtained and the cosmological parameters are constrained using
supernova type Ia data. In general, an open universe is predicted. A big rip
scenario is largely preferred, but the dispersion in the parameter space is
very high. Hence, even if scenarios without future singularities can not be
excluded with the allowed range of parameters, a phantom cosmology, with an
open spatial section, is a general prediction of the model. For a wide range of
the equation of state parameters there is an asymptotic de Sitter phase.


title:
The thermal Sunyaev-Zel'dovich Signature of Baryons in the Local
  Universe

abstract:
  Using cosmological hydrodynamical simulations, we investigate the prospects
of the thermal Sunyaev-Zel'dovich (tSZ) effect to detect the missing baryons in
the local universe. We find that at least 80% of the tSZ luminosity is
generated in collapsed structures, and that $\sim$ 70% of the remaining diffuse
tSZ luminosity (i.e., $\sim 15$% of the total) comes from overdense regions
with $\delta_{gas}>$10, such as filaments and superclusters. The gas present in
slightly overdense and underdense regions with $\delta_{gas} < 10$, despite
making up 50% of the total baryon budget, leaves very little tSZ signature: it
gives rise to only $\sim$ 5% of the total tSZ luminosity. Thus, future Cosmic
Microwave Background (CMB) observations will be sensitive to, at best, one half
of the missing baryons, improving the current observational status, but still
leaving one half unobserved. Since most of the tSZ is generated in haloes, we
find a tight correlation between gas pressure and galaxy number density. This
allows us to predict the CMB Comptonization from existing galaxy surveys and to
forecast the tSZ effect from the local structures probed by the Two Micron All
Sky Survey (2MASS) galaxy catalog.


title: Intracluster Planetary Nebulae

abstract:
  I review the progress in research on intracluster planetary nebulae over the
last five years. Hundreds more intracluster planetary nebulae have been
detected in the nearby Virgo and Fornax galaxy clusters, searches of several
galaxy groups have been made, and intracluster planetary candidates have been
detected in the distant Coma cluster. The first theoretical studies of
intracluster planetaries have also been completed, studying their utility as
tracers of the intracluster light as a whole, and also as individual objects.
  From the results to date, it appears that intracluster planetaries are common
in galaxy clusters (10-20% of the total amount of starlight), but thus far,
none have been detected in galaxy groups, a result which currently is not well
understood. Limited spectroscopic follow-up of intracluster planetaries in
Virgo indicate that they have a complex velocity structure, in agreement with
numerical models of intracluster light. Hydrodynamic simulations of individual
intracluster planetaries predict that their morphology is significantly altered
by their intracluster environment, but their emission-line properties appear to
be unaffected.


title:
On the role of continuum-driven eruptions in the evolution of very
  massive stars and Population III stars

abstract:
  We suggest that the mass lost during the evolution of very massive stars may
be dominated by optically thick, continuum-driven outbursts or explosions,
instead of by steady line-driven winds. In order for a massive star to become a
WR star, it must shed its H envelope, but new estimates of the effects of
clumping in winds indicate that line driving is vastly insufficient. We discuss
massive stars above roughly 40-50 Msun, for which the best alternative is mass
loss during brief eruptions of luminous blue variables (LBVs). Our clearest
example of this phenomenon is the 19th century outburst of eta Car, when the
star shed 12-20 Msun or more in less than a decade. Other examples are
circumstellar nebulae of LBVs, extragalactic eta Car analogs (``supernova
impostors''), and massive shells around SNe and GRBs. We do not yet fully
understand what triggers LBV outbursts, but they occur nonetheless, and present
a fundamental mystery in stellar astrophysics. Since line opacity from metals
becomes too saturated, the extreme mass loss probably arises from a
continuum-driven wind or a hydrodynamic explosion, both of which are
insensitive to metallicity. As such, eruptive mass loss could have played a
pivotal role in the evolution and fate of massive metal-poor stars in the early
universe. If they occur in these Population III stars, such eruptions would
profoundly affect the chemical yield and types of remnants from early SNe and
hypernovae.


title: The James Webb Space Telescope

abstract:
  The James Webb Space Telescope (JWST) is a large (6.6m), cold (50K),
infrared-optimized space observatory that will be launched early in the next
decade. The observatory will have four instruments: a near-infrared camera, a
near-infrared multi-object spectrograph, and a tunable filter imager will cover
the wavelength range, 0.6 to 5.0 microns, while the mid-infrared instrument
will do both imaging and spectroscopy from 5.0 to 29 microns. The JWST science
goals are divided into four themes. The End of the Dark Ages: First Light and
Reionization theme seeks to identify the first luminous sources to form and to
determine the ionization history of the early universe. The Assembly of
Galaxies theme seeks to determine how galaxies and the dark matter, gas, stars,
metals, morphological structures, and active nuclei within them evolved from
the epoch of reionization to the present day. The Birth of Stars and
Protoplanetary Systems theme seeks to unravel the birth and early evolution of
stars, from infall on to dust-enshrouded protostars to the genesis of planetary
systems. The Planetary Systems and the Origins of Life theme seeks to determine
the physical and chemical properties of planetary systems including our own,
and investigate the potential for the origins of life in those systems. To
enable these observations, JWST consists of a telescope, an instrument package,
a spacecraft and a sunshield. The telescope consists of 18 beryllium segments,
some of which are deployed. The segments will be brought into optical alignment
on-orbit through a process of periodic wavefront sensing and control. The JWST
operations plan is based on that used for previous space observatories, and the
majority of JWST observing time will be allocated to the international
astronomical community through annual peer-reviewed proposal opportunities.


title:
The Integral Field Unit for the Echellette Spectrograph and Imager at
  Keck II

abstract:
  We report on the design, development and commissioning of an Integral Field
Unit (IFU) that has been built for the Echellette Spectrograph and Imager (ESI)
at the W.M. Keck Observatory. This image slicer--based IFU, which was
commissioned in the spring of 2004 covers a contiguous field of 5.65 x 4.0
arcseconds in 5 slices that are 1.13 arcseconds wide. The IFU passes a spectral
range of 0.39-1.1 um with a throughput of between 45 % and 60 % depending on
wavelength and field position. The IFU head resides in an ESI slit mask holder,
so that ESI may be converted to the IFU mode remotely by selecting the
appropriate slit mask position. This IFU is the first of a family of designs
for the spectrograph, providing a range of field-coverages and dispersions. In
addition, we present the first-light science imaging and spectroscopic
observations of RXJ1131-123, a low-redshift, lensed quasar. These observations
show the 4 spectra of the lens and lensed-images captured in a single pointing.


title: Magnetospheric Gap and Accumulation of Giant Planets Close to the Star

abstract:
  The bunching of giant planets at a distance of several stellar radii may be
explained by the disruption of the inner part of the disk by the magnetosphere
of the star during the T Tauri stage of evolution. The rotating magnetic field
of the star gives rise to a low density magnetospheric gap where stellar
migration is strongly suppressed. We performed full 3D magnetohydrodynamic
simulations of the disk-magnetosphere interaction and examined conditions for
which the magnetospheric gap is "empty", by changing the misalignment angle
between magnetic and rotational axes of the star, Theta, and by lowering the
adiabatic index gamma, which mocks up the effect of heat conductivity and
cooling. Our simulations show that for a wide range of plausible conditions the
gap is essentially empty. However, in the case of large misalignment angles
Theta, part of the funnel stream is located in the equatorial plane and the gap
is not empty. Furthermore, if the adiabatic index is small (gamma=1.1) and the
rotational and magnetic axes are almost aligned, then matter penetrates through
the magnetosphere due to 3D instabilities forming high-density equatorial
funnels. For these two limits there is appreciable matter density in the
equatorial plane of the disk so that a planet may migrate into the star.


title:
Temperature dependence of charge transfer inefficiency in Chandra X-ray
  CCDs

abstract:
  Soon after launch, the Advanced CCD Imaging Spectrometer (ACIS), one of the
focal plane instruments on the Chandra X-ray Observatory, suffered radiation
damage from exposure to soft protons during passages through the Earth's
radiation belts. The primary effect of the damage was to increase the charge
transfer inefficiency (CTI) of the eight front illuminated CCDs by more than
two orders of magnitude. The ACIS instrument team is continuing to study the
properties of the damage with an emphasis on developing techniques to mitigate
CTI and spectral resolution degradation. We present the initial temperature
dependence of ACIS CTI from -120 to -60 degrees Celsius and the current
temperature dependence after more than six years of continuing slow radiation
damage. We use the change of shape of the temperature dependence to speculate
on the nature of the damaging particles.


title: MEMS-based Speckle Spectrometer

abstract:
  We describe a new concept for a MEMS-based active spatial filter for
astronomical spectroscopy. The goal of this device is to allow the use of a
diffraction-limited spectrometer on a seeing limited observation at improved
throughput over a comparable seeing-limited spectrometer, thus reducing the
size and cost of the spectrometer by a factor proportional to r0/D (For the
case of a 10 meter telescope this size reduction will be approximately a factor
of 25 to 50). We use a fiber-based integral field unit (IFU) that incorporates
an active MEMS mirror array to feed an astronomical spectrograph. A fast camera
is used in parallel to sense speckle images at a spatial resolution of lambda/D
and at a temporal frequency greater than that of atmospheric fluctuations. The
MEMS mirror-array is used as an active shutter to feed speckle images above a
preset intensity threshold to the spectrometer, thereby increasing the
signal-to-noise ratio (SNR) of the spectrogram. Preliminary calculations
suggests an SNR improvement of a factor of about 1.4. Computer simulations have
shown an SNR improvement of 1.1, but have not yet fully explored the parameter
space.


title: The detectability of HI 21-cm absorption in damped Lyman-alpha systems

abstract:
  In this paper we investigate the possible reasons why HI 21-cm absorption in
damped Lyman-alpha systems (DLAs) has only been detected at low redshift... We
suggest that the lack of 21-cm absorption detections at high redshift arises
from the fact that these DLAs are at similar angular diameter distances to the
background quasars (i.e. the distance ratios are always close to unity): Above
z~1.6 the covering factor becomes largely independent of the DLA--QSO distance,
making the high redshift absorbers much less effective at covering the
background continuum emission. At low redshift, small distance ratios are
strongly favoured by the 21-cm detections, whereas large ratios are favoured by
the non-detections. This mix of distance ratios gives the observed mix of
detections and non-detections at z<1.6.In addition to the predominance of large
distance ratios and non-detections at high redshift, this strongly suggests
that the observed distribution of 21-cm absorption in DLAs is dominated by
geometric effects.


title: Calibrating an Interferometric Null

abstract:
  One of the biggest challenges associated with a nulling interferometer-based
approach to detecting extra-solar Earth-like planets comes from the extremely
stringent requirements of pathlength, polarization and amplitude matching in
the interferometer. To the extent that the light from multiple apertures are
not matched in these properties, light will leak through the nuller and confuse
the search for a planetary signal. Here we explore the possibility of using the
coherence properties of the starlight to separate contributions from the planet
and nuller leakage. We find that straightforward modifications to the optical
layout of a nulling interferometer will allow one to measure and correct for
the leakage to a high degree of precision. This nulling calibration relaxes the
field matching requirements substantially, and should consequently simplify the
instrument design.


title:
Interferometric Observations of Explosive Variables: V838 Mon, Nova Aql
  2005, and RS Oph

abstract:
  During the last two years we have used the Palomar Testbed Interferometer to
observe several explosive variable stars, including V838 Monocerotis, V1663
Aquilae and recently RS Ophiuchi. We observed V838 Monocerotis approximately 34
months after its eruption, and were able to resolve the ejecta. Observations of
V1663 Aql were obtained starting 9 days after peak brightness and continued for
10 days. We were able to resolve the milliarcsecond-scale emission and follow
the expansion of the nova photosphere. When combined with radial-velocity
information, these observations can be used to infer the distance to the nova.
Finally we have resolved the recurrent nova RS Oph and can draw some
preliminary conclusions regarding the emission morphology.


title: Constraints on cosmological parameters

abstract:
  A cosmological model with total density close to critical (and flat
geometry), dominated by dark matter and dark energy of unknown nature, and
consistent with the basic predictions of the inflationary scenario is a very
good fit to a variety of cosmological probes: the anisotropy of the CMB, the
large scale distribution of matter, the luminosity distance of high-redshift
type Ia supernovae and so on. These high-quality data have established a new
standard of precision in the determination of cosmological parameters.


title:
X-ray thermal coronae of galaxies in hot clusters -- ubiquity of
  embedded mini cooling cores

abstract:
  We present a systematic investigation of X-ray thermal coronae in 157
early-type galaxies and 22 late-type galaxies from a survey of 25 hot (kT>3
keV), nearby (z<0.05) clusters, based on CHANDRA archival data. Cool galactic
coronae (kT=0.5-1.1 keV generally) have been found to be very common, >60% in
NIR selected galaxies that are more luminous than 2L*, and >40% in L* < L_Ks <
2L* galaxies. These embedded coronae in hot clusters are generally smaller
(1.5-4 kpc radii), less luminous (<~ 10^41 erg s^-1), and less massive
(10^6.5-10^8 M_solar}) than coronae in poor environments, demonstrating the
negative effects of hot cluster environments on galactic coronae. Nevertheless,
these coronae still manage to survive ICM stripping, evaporation, rapid
cooling, and powerful AGN outflows, making them a rich source of information
about gas stripping, microscopic transport, and feedback processes in the
cluster environment. Heat conduction across the boundary of the coronae has to
be suppressed by a factor of >100, which implies the X-ray gas in early-type
galaxies is magnetized and the magnetic field plays an important role in energy
transfer. Stripping through transport processes (viscosity or turbulence) also
needs to be suppressed by at least a factor of ten at the coronal boundary...
(abridged) Diffuse thermal coronae have also been detected in at least 8 of 22
late-type (Sb or later) galaxies in our sample. Evidence for enhanced star
formation triggered by the ICM pressure has been found in four late-type
galaxies. The fraction of luminous X-ray AGN (>10^41 ergs s^-1) is not small (~
5%) in our sample.


title:
Velocity-Metallicity Correlation for high-z DLA Galaxies: Evidence for a
  Mass-Metallicity Relation?

abstract:
  We used our database of VLT-UVES quasar spectra to build up a sample of 70
Damped Lyman-alpha (DLA) or strong sub-DLA systems with total neutral hydrogen
column densities of log N(HI)>20 and redshifts in the range 1.7<z_abs<4.3. For
each of the systems, we measured in an homogeneous manner the metallicities
relative to Solar, [X/H] (with X=Zn, or S or Si), and the velocity widths of
low-ionization line profiles, Delta V. We provide for the first time evidence
for a correlation between DLA metallicity and line profile velocity width,
which is detected at the 6.1sigma significance level. This confirms the trend
previously observed in a much smaller sample by Wolfe & Prochaska (1998). The
best-fit linear relation is [X/H]=1.55(\pm 0.12) log Delta V -4.33(\pm 0.23)
with Delta V expressed in km/s. The slope of the DLA velocity-metallicity
relation is the same within uncertainties between the higher (z_abs>2.43) and
the lower (z_abs<2.43) redshift halves of our sample. However, the two
populations of systems are statistically different. There is a strong redshift
evolution in the sense that the mean metallicity and mean velocity width
increase with decreasing redshift. We argue that the existence of a DLA
velocity-metallicity correlation, over more than a factor of 100 spread in
metallicity, is probably the consequence of an underlying mass-metallicity
relation for the galaxies responsible for DLA absorption lines. Assuming a
simple linear scaling of the galaxy luminosity with the mass of the dark-matter
halo, we find that the slope of the DLA velocity-metallicity relation is
consistent with that of the luminosity-metallicity relation derived for local
galaxies. [...] abridged.


title:
Near-Infrared and Star-forming properties of Local Luminous Infrared
  Galaxies

abstract:
  We use HST NICMOS continuum and Pa-alpha observations to study the
near-infrared and star-formation properties of a representative sample of 30
local (d ~ 35-75Mpc) luminous infrared galaxies (LIRGs, infrared 8-1000um
luminosities of L_IR=11-11.9[Lsun]). The data provide spatial resolutions of
25-50pc and cover the central ~3.3-7.1kpc regions of these galaxies. About half
of the LIRGs show compact (~1-2kpc) Pa-alpha emission with a high surface
brightness in the form of nuclear emission, rings, and mini-spirals. The rest
of the sample show Pa-alpha emission along the disk and the spiral arms
extending over scales of 3-7kpc and larger. About half of the sample contains
HII regions with H-alpha luminosities significantly higher than those observed
in normal galaxies. There is a linear empirical relationship between the mid-IR
24um and hydrogen recombination (extinction-corrected Pa-alpha) luminosity for
these LIRGs, and the HII regions in the central part of M51. This relation
holds over more than four decades in luminosity suggesting that the mid-IR
emission is a good tracer of the star formation rate (SFR). Analogous to the
widely used relation between the SFR and total IR luminosity of Kennicutt
(1998), we derive an empirical calibration of the SFR in terms of the
monochromatic 24um luminosity that can be used for luminous, dusty galaxies.


title:
Inelastic Neutrino-Helium Scatterings and Standing Accretion Shock
  Instability in Core-Collapse Supernovae

abstract:
  We present the results of numerical experiments, in which we have
investigated the influence of the inelastic neutrino-helium interactions on the
standing accretion shock instability supposed to occur in the post-bounce
supernova core. The axisymmetric hydrodynamical simulations of accretion flows
through the standing accretion shock wave onto the protoneutron star show that
the interactions are relatively minor and the linear growth of the shock
instability is hardly affected. The extra heating given by the inelastic
reactions becomes important for the shock revival after the instability enters
the non-linear regime, but only when the neutrino luminosity is very close to
the critical value, at which the shock would be revived without the
interactions. We have also studied the dependence of the results on the initial
amplitudes of perturbation and the temperatures of mu and tau neutrinos.


title: APEX CO(3-2) observations of NGC6822

abstract:
  We observed the CO(3-2) emission of the emission-line regions HubbleI,
HubbleV, HubbleX, Holmberg 18, and the stellar emission-line object S28 in
NGC6822 with the ESO Atacama Pathfinder Experiment (APEX) 12m telescope as part
of its science verification. The very low system temperature of 130-180K
enabled us to achieve detections in 4 single pointings and in a high spatial
resolution 70''x70'' map of HubbleV. We compare the spectra with HI
observations, obtained with the Australia Telescope Compact Array, of the same
regions. In combination with previous multi-line CO observations, we perform a
preliminary investigation of the physical conditions in HubbleV using a simple
LTE model. We estimate the mass of the HubbleV region and the H_2/I_CO(3-2)
conversion factor. Also, we show that HubbleV is located very near the
line-width versus size relation traced by the Milky Way and LMC molecular
clouds.


title: Extragalactic Relativistic Jets and Nuclear Regions in Galaxies

abstract:
  Past years have brought an increasingly wider recognition of the ubiquity of
relativistic outflows (jets) in galactic nuclei, which has turned jets into an
effective tool for investigating the physics of nuclear regions in galaxies. A
brief summary is given here of recent results from studies of jets and nuclear
regions in several active galaxies with prominent outflows.


title: Cosmological bounds on dark matter-neutrino interactions

abstract:
  We investigate the cosmological effects of a neutrino interaction with cold
dark matter. We postulate a neutrino that interacts with a ``neutrino
interacting dark matter'' (NIDM) particle with an elastic-scattering cross
section that either decreases with temperature as $T^2$ or remains constant
with temperature. The neutrino--dark-matter interaction results in a
neutrino--dark-matter fluid with pressure, and this pressure results in
diffusion-damped oscillations in the matter power spectrum, analogous to the
acoustic oscillations in the baryon-photon fluid. We discuss the bounds from
the Sloan Digital Sky Survey on the NIDM opacity (ratio of cross section to
NIDM-particle mass) and compare with the constraint from observation of
neutrinos from supernova 1987A. If only a fraction of the dark matter interacts
with neutrinos, then NIDM oscillations may affect current cosmological
constraints from measurements of galaxy clustering. We discuss how detection of
NIDM oscillations would suggest a particle-antiparticle asymmetry in the
dark-matter sector.


title:
RASS-SDSS Galaxy Cluster Survey. V. The X-ray-Underluminous Abell
  Clusters

abstract:
  In this paper we consider a large sample of optically selected clusters, in
order to elucidate the physical reasons for the existence of X-ray
underluminous clusters. For this purpose we analyze the correlations of the
X-ray and optical properties of a sample of 137 spectroscopically confirmed
Abell clusters in the SDSS database. We search for the X-ray counterpart of
each cluster in the ROSAT All Sky Survey. We find that 40% of our clusters have
a marginal X-ray detection or remain undetected in X-rays. These clusters
appear too X-ray faint on average for their velocity dispersion determined
mass, i.e. they do not follow the scaling relation between X-ray luminosity and
virial mass traced by the other clusters. On the other hand, they do follow the
general scaling relation between optical luminosity and virial mass. We refer
to these clusters as the X-ray-Underluminous Abell clusters (AXU clusters, for
short) and designate as 'normal' the X-ray detected Abell systems. We examine
the distributions and properties of the galaxy populations of the normal and
the AXU clusters, separately. The AXU clusters are characterized by leptokurtic
(more centrally concentrated than a Gaussian) velocity distribution of their
member galaxies in the outskirts ($1.5 < r/r_{200} \leq 3.5$), as expected for
the systems in accretion. In addition, the AXU clusters have a higher fraction
of blue galaxies in the external region and show a marginally significant
paucity of galaxies at the center. Our results seem to support the
interpretation that the AXU clusters are systems in formation undergoing a
phase of mass accretion. Their low X-ray luminosity should be due to the still
accreting Intracluster gas or to an ongoing merging process.


title: A systematic search for very massive galaxies at z > 4

abstract:
  Motivated by the claimed discovery of a very massive galaxy (HUDF-JD2;
M~5x10^11 Msun) at extreme redshift (z = 6.5) within the Hubble Ultra Deep
Field (HUDF) (Mobasher et al. 2005), we have completed a systematic search for
comparably massive galaxies with z > 4 among the 2688 galaxies in our K < 23.5
(AB) catalogue within the CDFS/GOODS-South field. This search was conducted
using redshift estimates based on the recently-completed, uniquely-deep 11-band
imaging in this 125 square arcmin field, ~25 times larger than the NICMOS HUDF.
Initial spectral fitting, based on published catalogue SExtractor photometry,
led us to conclude that at least 2669 of the galaxies in our sample lie at z <
4. We carried out a detailed investigation of the 19 remaining z > 4
candidates, performing aperture photometry on all images, and including
marginal detections and formal non-detections in the fitting process. This led
to the rejection of a further 13 galaxies to lower redshift. Moreover,
subjecting HUDF-JD2 to the same analysis, we find that it lies at z ~ 2.2,
rather than the extreme redshift favoured by Mobasher et al. (2005). The 6
remaining candidates appear to be credible examples of galaxies in the redshift
range z = 4 - 6, with plausible stellar ages. However, refitting with allowance
for extreme values of extinction we find that, even for these objects,
statistically acceptable solutions can be found at z < 3. Moreover, the
recently-released Spitzer MIPS imaging in GOODS-South has revealed that 5 of
our 6 final z > 4 candidates are detected at 24 microns. We conclude that there
is no convincing evidence for any galaxy with M > 3 x 10^11 Msun, and z > 4
within the GOODS-South field (abridged).


title: URAT: astrometric requirements and design history

abstract:
  The U.S. Naval Observatory Robotic Astrometric Telescope (URAT) project aims
at a highly accurate (5 mas), ground-based, all-sky survey. Requirements are
presented for the optics and telescope for this 0.85 m aperture, 4.5 degree
diameter field-of-view, specialized instrument, which are close to the
capability of the industry. The history of the design process is presented as
well as astrometric performance evaluations of the toleranced, optical design,
with expected wavefront errors included.


title:
Modeling the Broadband Spectral Energy Distribution of the Microquasars
  XTE J1550-564 and H 1743-322

abstract:
  We report results from a systematic study of the spectral energy distribution
(SED) and spectral evolution of XTE J1550--564 and H 1743--322 in outburst. The
jets of both sources have been directly imaged at both radio and X-ray
frequencies, which makes it possible to constrain the spectrum of the radiating
electrons in the jets. We modelled the observed SEDs of the jet `blobs' with
synchrotron emission alone and with synchrotron emission plus inverse Compton
scattering. The results favor a pure synchrotron origin of the observed jet
emission. Moreover, we found evidence that the shape of the electron spectral
distribution is similar for all jet `blobs' seen. Assuming that this is the
case for the jet as a whole, we then applied the synchrotron model to the radio
spectrum of the total emission and extrapolated the results to higher
frequencies. In spite of significant degeneracy in the fits, it seems clear
that, while the synchrotron radiation from the jets can account for nearly 100%
of the measured radio fluxes, it contributes little to the observed X-ray
emission, when the source is relatively bright. In this case, the X-ray
emission is most likely dominated by emission from the accretion flows. When
the source becomes fainter, however, the jet emission becomes more important,
even dominant, at X-ray energies. We also examined the spectral properties of
the sources during outbursts and the correlation between the observed radio and
X-ray variabilities. The implication of the results is discussed.


title:
Three-Dimensional Simulations of Spherical Accretion Flows with
  Small-Scale Magnetic Fields

abstract:
  Spherical (nonrotating) accretion flows with small-scale magnetic fields have
been investigated using three-dimensional, time-dependent MHD simulations.
These simulations have been designed to model high-resolution (quasi) steady
accretion flows in a wedge computational domain that represents a small
fraction of the full spherical domain. Subsonic and supersonic
(super-fast-magnetosonic) accretion flows have been considered. Two accretion
regimes have been studied: conservative, or radiatively inefficient, and
nonconservative, in which the heat released in magnetic reconnections is
completely lost. The flows in both regimes are turbulent. They show the
flattened radial density profiles and reduction of the accretion velocities and
mass accretion rates in comparison with hydrodynamic Bondi flows. In the
conservative regime, the turbulence is more intensive and supported mostly by
thermal convection. In the nonconservative regime, the turbulence is less
intensive and supported by magnetic buoyancy and various magnetic interactions.
We have concluded that steady, supersonic spherical accretion cannot be
developed in the presence of small-scale magnetic fields.


title: Overcoming the Rayleigh Criterion Limit with Optical Vortices

abstract:
  We experimentally and numerically tested the separability of two independent
equally-luminous monochromatic and white light sources at the diffraction
limit, using Optical Vortices (OV), related to the Orbital Angular Momentum
(OAM) of light. The diffraction pattern of one of the two sources crosses a
phase modifying device (fork-hologram) on its center generating the
Laguerre-Gaussian (L-G) transform of an Airy disk. The second source, crossing
the fork-hologram in positions different from the optical center, acquires
different OAM values and generates non-symmetric L-G patterns. We formulated a
criterion, based on the asymmetric intensity distribution of the superposed L-G
patterns so created, to resolve the two sources at angular distances much below
the Rayleigh criterion. Analogous experiments carried out in white light allow
angular resolutions which are still one order of magnitude below the Rayleigh
criterion. The use OVs might offer new applications for stellar separation in
future space experiments.


title:
Dark matter vs. modifications of the gravitational inverse-square law.
  Results from planetary motion in the solar system

abstract:
  Dark matter or modifications of the Newtonian inverse-square law in the
solar-system are studied with accurate planetary astrometric data. From
extra-perihelion precession and possible changes in the third Kepler's law, we
get an upper limit on the local dark matter density, rho_{DM} < 3*10^{-16}
kg/m^3 at the 2-sigma confidence level. Variations in the 1/r^2 behavior are
considered in the form of either a possible Yukawa-like interaction or a
modification of gravity of MOND type. Up to scales of 10^{11} m,
scale-dependent deviations in the gravitational acceleration are really small.
We examined the MOND interpolating function mu in the regime of strong gravity.
Gradually varying mu suggested by fits of rotation curves are excluded, whereas
the standard form mu(x)= x/(1+x^2)^{1/2} is still compatible with data. In
combination with constraints from galactic rotation curves and theoretical
considerations on the external field effect, the absence of any significant
deviation from inverse square attraction in the solar system makes the range of
acceptable interpolating functions significantly narrow. Future radio ranging
observations of outer planets with an accuracy of few tenths of a meter could
either give positive evidence of dark matter or disprove modifications of
gravity.


title: Nuclear activity in galaxies driven by binary supermassive black holes

abstract:
  Nuclear activity in galaxies is closely connected to galactic mergers and
supermassive black holes (SBH). Galactic mergers perturb substantially the
dynamics of gas and stellar population in the merging galaxies, and they are
expected to lead to formation of supermassive binary black holes (BBH) in the
center of mass of the galaxies merged. A scheme is proposed here that connects
the peak magnitude of the nuclear activity with evolution of a BBH system. The
scheme predicts correctly the relative fractions of different types of active
galactic nuclei (AGN) and explains the connection between the galactic type and
the strength of the nuclear activity. It shows that most powerful AGN should
result from mergers with small mass ratios, while weaker activity is produced
in unequal mergers. The scheme explains also the observed lack of galaxies with
two active nuclei, which is attributed to effective disruption of accretion
disks around the secondary in BBH systems with masses of the primary smaller
than ~10^10 solar masses.


title:
Comparison of filters for the detection of point sources in Planck
  simulations

abstract:
  We study the detection of extragalactic point sources in two-dimensional flat
simulations for all the frequencies of the forthcoming ESA's Planck mission. In
this work we have used the most recent available templates of the microwave
sky: as for the diffuse Galactic components and the Sunyaev-Zel'dovich clusters
we have used the ``Plank Reference Sky Model''; as for the extragalactic point
sources, our simulations - which comprise all the source populations relevant
in this frequency interval - are based on up-to-date cosmological evolution
models for sources. To consistently compare the capabilities of different
filters for the compilation of the - hopefully - most complete blind catalogue
of point sources, we have obtained three catalogues by filtering the simulated
sky maps with: the Matched Filter (MF), the Mexican Hat Wavelet (MHW1) and the
Mexican Hat Wavelet 2 (MHW2), the first two members of the MHW Family. For the
nine Planck frequencies we show the number of real and spurious detections and
the percentage of spurious detections at different flux detection limits as
well as the completeness level of the catalogues and the average errors in the
estimation of the flux density of detected sources. Allowing a 5 % of spurious
detections, we obtain the following number of detections by filtering with the
MHW2 an area equivalent to half of the sky: 580 (30 GHz), 342 (44 GHz), 341 (70
GHz), 730 (100 GHz), 1130 (143 GHz), 1233 (217 GHz), 990 (353 GHz), 1025 (545
GHz) and 3183 (857 GHz). Our current results indicate that the MF and the MHW2
yield similar results, whereas the MHW1 performs worse in some cases and
especially at very low fluxes. This is a relevant result, because we are able
to obtain comparable results with the well known Matched Filter and with this
specific wavelet, the MHW2, which is much easier to implement and use.


title: On the metallicity dependence of HMXBs

abstract:
  It is commonly assumed that high mass X-ray binary (HMXB) populations are
little-affected by metallicity. However, the massive stars making up their
progenitor systems depend on metallicity in a number of ways, not least through
their winds. We present simulations, well-matched to the observed sample of
Galactic HMXBs, which demonstrate that both the number and the mean period of
HMXB progenitors can vary with metallicity, with the number increasing by about
a factor of three between solar and SMC metallicity. However, the SMC
population itself cannot be explained simply by metallicity effects; it
requires both that the HMXBs observed therein primarily sample the older end of
the HMXB population, and that the star formation rate at the time of their
formation was very large.


title: The Long Bar in the Milky Way. Corroboration of an old hypothesis

abstract:
  Recent GLIMPSE data have further confirmed the hypothesis of the existence of
an in-plane long bar different from the bulge of the Milky Way with the same
characteristics as emphasized some years ago by our team. In this paper, we
present two new analyses that corroborate recent and earlier claims concerning
the existence in our Galaxy of a long flat bar with approximate dimensions 7.8
kpc x 1.2 kpc x 0.2 kpc and a position angle of approximately 43 deg.: 1) star
counts with 2MASS All-Sky Release and MSX data, which give an excess in the
plane region along 0<l<30 deg. compared with -30 deg.<l<0, and which cannot be
due to the bulge, spiral arms, a ring, or extinction; 2) new data on the
distance of the long bar using the red clump method, together with recent
observations of our own that are compared with our model, and that are in
agreement with the long-bar scenario.


title:
First Spitzer Space Telescope Observations of Magnetic Cataclysmic
  Variables: Evidence for Excess Emission at 3--8 microns

abstract:
  We present the first observations of magnetic cataclysmic variables with the
Spitzer Space Telescope. We used the Infrared Array Camera to obtain photometry
of the polars EF Eri, GG Leo, V347 Pav, and RX J0154.0-5947 at 3.6, 4.5, 5.8,
and 8.0 $\mu$m. In all of our targets, we detect excess mid-infrared emission
over that expected from the component stars alone. We explore the origin of
this IR excess by examining bremsstrahlung, cyclotron emission, circumbinary
dust, and L/T brown dwarf secondary stars. Bremsstrahlung and cyclotron
emission appear unlikely to be significant contributors to the observed fluxes.
At present, the most likely candidate for the excess emission is dust that is
probably located in a circumbinary disk with an inner temperature near 800 K.
However, a simple dust disk plus any reasonable low mass or brown dwarf-like
secondary star is unable to fully explain the observed flux densities in the
3--8 $\mu$m region.


title: Faint flux performance of an EMCCD

abstract:
  Thorough numerical simulations were run to test the performance of three
processing methods of the data coming out from an electron multiplying charge
coupled device (EMCCD), or low light level charge coupled device (L3CCD),
operated at high gain, under real operating conditions. The effect of read-out
noise and spurious charges is tested under various low flux conditions (0.001
event/pixel/frame < f < 20 events/pixel/frame). Moreover, a method for finding
the value of the gain applied by the EMCCD amplification register is also
developed. It allows one to determine the gain value to an accuracy of a
fraction of a percent from dark frames alone.


title: Are Gamma-ray Bursts Universal?

abstract:
  It is noted that the Liang-Zhang correlation can be accounted for with the
viewing angle interpretation proposed earlier. The Ghirlanda correlation,
recently generalized by Nava et al (2006) to a wind profile, can be accounted
for by the viewing angle interpretation accordingly generalized to a wind
profile. Most of the scatter in the spectra and time-integrated brightness in
$\gamma$-ray bursts (GRB) can thus be accounted for by variation in two
parameters, 1) the viewing angle and 2) the jet opening angle, with very little
variation in any other intrinsic parameters. The scatter in apparent isotropic
equivalent fluence and other parameters is reduced by a factor of order 30 when
each of these parameters is considered. Possible difficulties with alternative
explanations are briefly discussed. It is also noted that the relative scatter
in the Amati and Ghirlanda correlations suggests certain conclusions about the
inner engine.


title: The Dynamical Evolution of Planetary Nebulae After the Fast Wind

abstract:
  In this paper we explore the dynamics of ionization bounded planetary nebulae
after the termination of the fast stellar wind. When the stellar wind becomes
negligible, the hot, shocked bubble depressurizes and the thermal pressure of
the photoionized region, at the inner edge of the swept-up shell, becomes
dominant. At this stage the shell tends to fragment creating clumps with
comet-like tails and long, photoionized trails in between, while the
photoionized material expands back towards the central stars as a rarefaction
wave. Once that the photoionized gas fills the inner cavity, it develops a
kinematical pattern of increasing velocity from the center outwards with a
typical range of velociti es starting from the systemic velocity to 50 Km/s at
the edges. The Helix nebula is a clear example of a planetary nebula at this
late evolutionary stage.


title: The Cosmological Evolution of the Average Mass Per Baryon

abstract:
  Subsequent to the early Universe quark-hadron transition the universal baryon
number is carried by nucleons: neutrons and protons. The total number of
nucleons is preserved as the Universe expands, but as it cools lighter protons
are favored over heavier neutrons reducing the average mass per baryon. During
primordial nucleosynthesis free nucleons are transformed into bound nuclides,
primarily helium, and the nuclear binding energies are radiated away, further
reducing the average mass per baryon. In particular, the reduction in the
average mass per baryon resulting from Big Bang Nucleosynthesis (BBN) modifies
the numerical factor relating the baryon (nucleon) mass and number densities.
Here the average mass per baryon, m_B, is tracked from the early Universe to
the present. The result is used to relate the present ratio of baryons to
photons (by number) to the present baryon mass density at a level of accuracy
commensurate with that of recent cosmological data, as well as to estimate the
energy released during post-BBN stellar nucleosynthesis.


title: Low Mach number modeling of Type I X-ray burst deflagrations

abstract:
  The Low Mach Number Approximation (LMNA) is applied to 2D hydrodynamical
modeling of Type I X-ray bursts on a rectangular patch on the surface of a
non-rotating neutron star. Because such phenomena involve decidedly subsonic
flows, the timestep increase offered by the LMNA makes routine simulations of
these deflagrations feasible in an environment where strong gravity produces
significant stratification, while allowing for potentially significant lateral
differences in temperature and density. The model is employed to simulate the
heating, peak, and initial cooling stages in the deep envelope layers of a
burst. During the deflagration, Benard-like cells naturally fill up a
vertically expanding convective layer. The Mach number is always less than 0.15
throughout the simulation, thus justifying the low Mach number approximation.
While the convective layer is superadiabatic on average, significant
fluctuations in adiabaticity occur within it on subconvective timescales. Due
to convective layer expansion, significant compositional mixing naturally
occurs, but tracer particle penetration through the convective layer boundaries
on convective timescales is temporary and spatially limited. Thus, mixing
occurs on the relatively slow burst timescale through thermal expansion of the
convective layer rather than from mass penetration of the convective layer
boundary through particle convection. At the convective layer boundaries where
mixing is less efficient, the actual temperature gradient more closely follows
the Ledoux criteria.


title: Proper motion of gamma-rays from microhalo sources

abstract:
  I discuss the prospects of detecting the smallest dark matter bound
structures present in the Milky Way by searching for the proper motion of
$\gamma$-ray sources in the upcoming GLAST all sky map. I show that for dark
matter particle candidates that couple to photons the detection of at least one
$\gamma$-ray microhalo source with proper motion places a constraint on the
couplings and mass of the dark matter particle. For SUSY dark matter, proper
motion detection implies that the mass of the particle is less than 500 GeV and
the kinetic decoupling temperature is in the range of [4-100] MeV.


title:
Big Bang Nucleosynthesis with Bound States of Long-lived Charged
  Particles

abstract:
  Charged particles (X) decaying after primordial nucleosynthesis are
constrained by the requirement that their decay products should not change the
light element abundances drastically. If the decaying particle is negatively
charged (X-) then it will bind to the nuclei. We consider the effects of the
decay of X when bound to Helium-4 and show that this will modify the Lithium
abundances.


title:
A New Einstein Cross: A Highly Magnified, Intrinsically Faint
  Lyman-Alpha Emitter at z=2.7

abstract:
  We report the discovery of a new Einstein cross at redshift z_S = 2.701 based
on Lyman-alpha emission in a cruciform configuration around an SDSS luminous
red galaxy (z_L = 0.331). The system was targeted as a possible lens based on
an anomalous emission line in the SDSS spectrum. Imaging and spectroscopy from
the W. M. Keck Observatory confirm the lensing nature of this system. This is
one of the widest-separation galaxy-scale lenses known, with an Einstein radius
of ~1.84 arcsec. We present simple gravitational lens models for the system and
compute the intrinsic properties of the lensed galaxy. The total mass of the
lensing galaxy within the 8.8 +/- 0.1 kpc enclosed by the lensed images is (5.2
+/- 0.1) x 10^11 M_sun. The lensed galaxy is a low mass galaxy (0.2 L*) with a
high equivalent-width Lyman-alpha line (EW_Lya_rest = 46 +/- 5 Angstroms).
Follow-up studies of this lens system can probe the mass structure of the
lensing galaxy, and can provide a unique view of an intrinsically faint,
high-redshift, star-forming galaxy at high signal-to-noise ratio.


title: The Radial Velocity Experiment (RAVE): first data release

abstract:
  We present the first data release of the Radial Velocity Experiment (RAVE),
an ambitious spectroscopic survey to measure radial velocities and stellar
atmosphere parameters (temperature, metallicity, surface gravity) of up to one
million stars using the 6dF multi-object spectrograph on the 1.2-m UK Schmidt
Telescope of the Anglo-Australian Observatory (AAO). The RAVE program started
in 2003, obtaining medium resolution spectra (median R=7,500) in the Ca-triplet
region ($\lambda\lambda$ 8,410--8,795 \AA) for southern hemisphere stars drawn
from the Tycho-2 and SuperCOSMOS catalogs, in the magnitude range 9<I<12. The
first data release is described in this paper and contains radial velocities
for 24,748 individual stars (25,274 measurements when including
re-observations). Those data were obtained on 67 nights between 11 April 2003
to 03 April 2004. The total sky coverage within this data release is
$\sim$4,760 square degrees. The average signal to noise ratio of the observed
spectra is 29.5, and 80% of the radial velocities have uncertainties better
than 3.4 km/s. Combining internal errors and zero-point errors, the mode is
found to be 2 km/s. Repeat observations are used to assess the stability of our
radial velocity solution, resulting in a variance of 2.8 km/s. We demonstrate
that the radial velocities derived for the first data set do not show any
systematic trend with color or signal to noise. The RAVE radial velocities are
complemented in the data release with proper motions from Starnet 2.0, Tycho-2
and SuperCOSMOS, in addition to photometric data from the major optical and
infrared catalogs (Tycho-2, USNO-B, DENIS and 2MASS). The data release can be
accessed via the RAVE webpage: http://www.rave-survey.org.


title: Properties of galaxies in SDSS Quasar environments at z < 0.2

abstract:
  We analyse the environment of low redshift, z < 0.2, SDSS quasars using the
spectral and photometric information of galaxies from the Sloan Digital Sky
Survey Third Data Release (SDSS-DR3). We compare quasar neighbourhoods with
field and high density environments through an analysis on samples of typical
galaxies and groups. We compute the surrounding surface number density of
galaxies finding that quasar environments systematically avoid high density
regions. Their mean environments correspond to galaxy density enhancements
similar to those of typical galaxies. We have also explored several galaxy
properties in these environments, such as spectral types, specific star
formation rates, concentration indexes, colours and active nuclei activity. We
conclude that low redshift quasar neighbourhoods (r_p < 1 Mpc h^-1, Delta V <
500 km/s) are populated by bluer and more intense star forming galaxies of
disk-type morphology than galaxies in groups and in the field. Although star
formation activity is thought to be significantly triggered by interactions, we
find that quasar fueling may not require the presence of a close companion
galaxy (r_p < 100 kpc h^-1, Delta V< 350 km/s). As a test of the unified AGN
model, we have performed a similar analysis to the neighbours of a sample of
active galaxies. The results indicate that these neighbourhoods are comparable
to those of quasars giving further support to this unified scenario.


title: Discovery of an 86 AU Radius Debris Ring Around HD 181327

abstract:
  HST/NICMOS PSF-subtracted coronagraphic observations of HD 181327 have
revealed the presence of a ring-like disk of circumstellar debris seen in 1.1
micron light scattered by the disk grains, surrounded by a di use outer region
of lower surface brightness. The annular disk appears to be inclined by 31.7
+/- 1.6 deg from face on with the disk major axis PA at 107 +/-2 deg . The
total 1.1 micron flux density of the light scattered by the disk (at 1.2" < r <
5.0") of 9.6 mJy +/- 0.8 mJy is 0.17% +/- 0.015% of the starlight. Seventy
percent of the light from the scattering grains appears to be confined in a 36
AU wide annulus centered on the peak of the radial surface brightness (SB)
profile 86.3 +/- 3.9 AU from the star, well beyond the characteristic radius of
thermal emission estimated from IRAS and Spitzer flux densities assuming
blackbody grains (~ 22 AU). The light scattered by the ring appears bilaterally
symmetric, exhibits directionally preferential scattering well represented by a
Henyey-Greenstein scattering phase function with g = 0.30 +/- 0.03, and has an
azimuthally medianed SB at the 86.3 AU radius of peak SB of 1.00 +/- 0.07 mJy
arcsec^-2. No photocentric offset is seen in the ring relative to the position
of the central star. A low surface brightness diffuse halo is seen in the
NICMOS image to a distance of ~ 4" Deeper 0.6 micron HST/ACS PSF-subtracted
coronagraphic observations reveal a faint outer nebulosity, asymmetrically
brighter to the North of the star. We discuss models of the disk and properties
of its grains, from which we infer a maximum vertical scale height of 4 - 8 AU
at the 87.6 AU radius of maximum surface density, and a total maximum dust mass
of collisionally replenished grains with minimum grain sizes of ~ 1 micron of ~
4 M(moon).


title: Quasars: What turns them off?

abstract:
  (Abridged) We explore the idea that the anti-hierarchical turn-off observed
in the quasar population arises from self-regulating feedback, via an outflow
mechanism. Using a detailed hydrodynamic simulation we calculate the luminosity
function of quasars down to a redshift of z=1 in a large, cosmologically
representative volume. Outflows are included explicitly by tracking halo
mergers and driving shocks into the surrounding intergalactic medium. Our
results are in excellent agreement with measurements of the spatial
distribution of quasars, and we detect an intriguing excess of galaxy-quasar
pairs at very short separations. We also reproduce the anti-hierarchical
turnoff in the quasar luminosity function, however, the magnitude of the
turn-off falls short of that observed as well as that predicted by analogous
semi-analytic models. The difference can be traced to the treatment of gas
heating within galaxies. The simulated galaxy cluster L_X-T relationship is
close to that observed for z~1 clusters, but the simulated galaxy groups at z=1
are significantly perturbed by quasar outflows, suggesting that measurements of
X-ray emission in high-redshift groups could well be a "smoking gun" for the
AGN heating hypothesis.


title:
The Hot Interstellar Medium of Normal Elliptical Galaxies. I. A Chandra
  Gas Gallery and Comparison of X-ray and Optical Morphology

abstract:
  We present an X-ray analysis of 54 normal elliptical galaxies in the Chandra
archive and isolate their hot gas component from the contaminating point source
emission, allowing us to conduct, for the first time, a morphological analysis
on the gas alone. A comparison with optical images and photometry shows that
the hot gas morphology has surprisingly little in common with the shape of the
stellar distribution. We observe no correlation between optical and X-ray
ellipticities in the inner regions where stellar mass dominates over dark
matter. A shallow correlation would be expected if the gas had settled into
hydrostatic equilibrium with the gravitational potential. Instead, observed
X-ray ellipticities exceed optical ellipticities in many cases. We exclude
rotation as the dominant factor to produce the gas ellipticities. The gas
appears disturbed, and hydrostatic equilibrium is the exception rather than the
rule. Nearly all hydrostatic models can be ruled out at 99% confidence, based
of their inability to reproduce the optical-X-ray correlation and large X-ray
ellipticities. Hydrostatic models not excluded are those in which dark matter
either dominates over stellar mass inside the inner half-light radius or has a
prominently cigar-shaped distribution, both of which can be ruled out on other
grounds. We conclude that, even for rather X-ray faint elliptical galaxies, the
gas is at least so far out of equilibrium that it does not retain any
information about the shape of the potential, and that X-ray derived radial
mass profiles may be in error by factors of order unity.


title:
Can MOND take a bullet? Analytical comparisons of three versions of MOND
  beyond spherical symmetry

abstract:
  A proper test of Modified Newtonian Dynamics (MOND) in systems of non-trivial
geometries depends on modelling subtle differences in several versions of its
postulated theories. This is especially important for lensing and dynamics of
barely virialised galaxy clusters with typical gravity of scale $\sim a_0 \sim
1\AA{\rm s}^{-2}$. The original MOND formula, the classical single field
modification of the Poisson equation, and the multi-field general relativistic
theory of Bekenstein (TeVeS) all lead to different predictions as we stray from
spherical symmetry. In this paper, we study a class of analytical MONDian
models for a system with a semi-Hernquist baryonic profile. After presenting
the analytical distribution function of the baryons in spherical limits, we
develop orbits and gravitational lensing of the models in non-spherical
geometries. In particular, we can generate a multi-centred baryonic system with
a weak lensing signal resembling that of the merging galaxy cluster 1E 0657-56
with a bullet-like light distribution. We finally present analytical scale-free
highly non-spherical models to show the subtle differences between the single
field classical MOND theory and the multi-field TeVeS theory.


title:
An inner disk below the ADAF: the intermediate spectral state of black
  hole accretion

abstract:
  Aims: The hard and soft spectral states of black hole accretion are
understood as connected with ADAF accretion (truncated disk) and standard disk
accretion, respectively. However, observations indicate the existence of cool
gas in the inner region at times when the disk is already truncated outside. We
try to shed light on these not yet understood intermediate states. Methods: The
disk-corona model allows to understand the spectral state transitions as caused
by changes of the mass flow rate in the disk and provides a picture for the
accretion geometry when disk truncation starts at the time of the soft/hard
transition, the formation of a gap in the disk filled by an advection-dominated
flow (ADAF) at the distance where the evaporation is maximal. We study the
interaction of such an ADAF with an inner thin disk below. Results: We show
that, when the accretion rate is not far below the transition rate, an inner
disk could exist below an ADAF, leading to an intermediate state of black hole
accretion.


title: The Red Halo Phenomenon

abstract:
  Optical and near-IR observations of the halos of disk galaxies and blue
compact galaxies have revealed a very red spectral energy distribution, which
cannot easily be reconciled with a normal, metal-poor stellar population like
that in the stellar halo of the Milky Way. Here, spectral evolutionary models
are used to explore the consequences of these observations. We demonstrate that
a stellar population of low to intermediate metallicity, but with an extremely
bottom-heavy initial mass function, can explain the red halos around both types
of objects. Other previously suggested explanations, like nebular emission or
very metal-rich stars, are shown to fail in this respect. This indicates that,
if the reported halo colours are correct, halo populations dominated by
low-mass stars may be a phenomenon common to galaxies of very different Hubble
types. Potential tests of this hypothesis are discussed, along with its
implications for the baryonic dark matter content of galaxies.


title: Filling the Infrared Gap: ISO Observations of 1 Jy BL Lacertae Objects

abstract:
  The large majority of BL Lacertae objects belonging to the 1 Jy sample, the
class prototype for radio-selected sources, are thought to emit most of their
synchrotron power in the far IR band. Ironically, this spectral region is very
sparsely sampled, with only a minority of the objects having IRAS data (most of
them being upper limits or low-quality detections). We aim at filling this IR
gap by presenting new, simultaneous ISOCAM and ISOPHOT observations over the 7
- 200 micron range for half the sample. A measurement of the position of the
synchrotron peak frequency, nu_peak, can provide information about particle
acceleration mechanisms and constrain the inverse Compton radiation that will
be detected by up-coming new gamma-ray missions. We have observed 17 1 Jy BL
Lacertae objects with the camera and the photometer on board the Infrared Space
Observatory (ISO) satellite. The ISOPHOT data reduction was done employing a
novel correction, which mitigates the effect of chopping for faint sources.
Using our new ISO data, complemented by nearly-simultaneous radio and optical
observations for 10 and 4 objects respectively, and other multi-frequency data,
we have built the spectral energy distributions of our sources (plus a
previously published one) and derived the rest-frame nu_peak. Its distribution
is centered at 10^13 Hz (30 micron) and is very narrow, with 60% of the BL Lacs
in the 1 - 3 10^13 Hz range. Given our set of simultaneous infrared data, these
represent the best determinations available of the synchrotron peak frequencies
for low-energy peaked BL Lacs. A comparison with previous such estimates, based
on non-simultaneous optical and near IR data, may indicate strong nu_peak
variations in a number of sources, possibly associated with large flares as
observed in the high-energy peaked BL Lac MKN 501. (abridged)


title:
Abundance Anomalies in Galactic Globular Clusters - Looking for the
  Stellar Culprits

abstract:
  Galactic globular cluster stars exhibit abundance patterns which are not
shared by their field counterparts. It is clear from recent spectroscopic
observations of GC turnoff stars that these abundance anomalies were already
present in the gas from which the observed stars formed. This provides
undisputed support to the so-called self-enrichment scenario according to which
a large fraction of GC low-mass stars have formed from material processed
through hydrogen-burning at high temperatures and then lost by more massive and
faster evolving stars (and perhaps mixed with some original gas). Within this
framework we present a new method to derive the Initial Mass Function of the
polluter stars.


title: Computing secular motion under slowly rotating quadratic perturbation

abstract:
  We consider secular perturbations of nearly Keplerian two-body motion under a
perturbing potential that can be approximated to sufficient accuracy by
expanding it to second order in the coordinates. After averaging over time to
obtain the secular Hamiltonian, we use angular momentum and eccentricity
vectors as elements. The method of variation of constants then leads to a set
of equations of motion that are simple and regular, thus allowing efficient
numerical integration. Some possible applications are briefly described.


title: Fourier phase analysis in radio-interferometry

abstract:
  Most statistical tools used to characterize the complex structures of the
interstellar medium can be related to the power spectrum, and therefore to the
Fourier amplitudes of the observed fields. To tap into the vast amount of
information contained in the Fourier phases, one may consider the probability
distribution function (PDF) of phase increments, and the related concepts of
phase entropy and phase structure quantity. We use these ideas here with the
purpose of assessing the ability of radio-interferometers to detect and recover
this information. By comparing current arrays such as the VLA and Plateau de
Bure to the future ALMA instrument, we show that the latter is definitely
needed to achieve significant detection of phase structure, and that it will do
so even in the presence of a fair amount of atmospheric phase fluctuations. We
also show that ALMA will be able to recover the actual "amount'' of phase
structure in the noise-free case, if multiple configurations are used.


title: Galaxy number counts in a presence of the graviton background

abstract:
  In the model of low-energy quantum gravity by the author, cosmological
redshifts are caused by interactions of photons with gravitons. Non-forehead
collisions with gravitons will lead to an additional relaxation of any photonic
flux. Using only the luminosity distance and a geometrical one as functions of
a redshift in this model, theoretical predictions for galaxy number counts are
considered here. The Schechter luminosity function with $\alpha =-2.43$ is
used. The considered model provides a good fit to galaxy observations by Yasuda
et al. (AJ, 122 (2001) 1104) if the same K-corrections are added. It is shown
that observations of $N(z)$ for different magnitudes $m$ are a lot more
informative than the ones of $N(m).$


title:
An asymmetric shock wave in the 2006 outburst of the recurrent nova RS
  Ophiuchi

abstract:
  Nova outbursts take place in binary star systems comprising a white dwarf and
either a low-mass Sun-like star or, as in the case of the recurrent nova RS
Ophiuchi, a red giant. Although the cause of these outbursts is known to be
thermonuclear explosion of matter transferred from the companion onto the
surface of the white dwarf, models of the previous (1985) outburst of RS
Ophiuchi failed to adequately fit the X-ray evolution and there was controversy
over a single-epoch high-resolution radio image, which suggested that the
remnant was bipolar rather than spherical as modelled. Here we report the
detection of spatially resolved structure in RS Ophiuchi from two weeks after
its 12 February 2006 outburst. We track an expanding shock wave as it sweeps
through the red giant wind, producing a remnant similar to that of a type II
supernova but evolving over months rather than millennia. As in supernova
remnants, the radio emission is non-thermal (synchrotron emission), but
asymmetries and multiple emission components clearly demonstrate that contrary
to the assumptions of spherical symmetry in models of the 1985 explosion, the
ejection is jet-like, collimated by the central binary whose orientation on the
sky can be determined from these observations.


title: Population analysis of open clusters: radii and mass segregation

abstract:
  Aims: Based on our well-determined sample of open clusters in the all-sky
catalogue ASCC-2.5 we derive new linear sizes of some 600 clusters, and
investigate the effect of mass segregation of stars in open clusters. Methods:
Using statistical methods, we study the distribution of linear sizes as a
function of spatial position and cluster age. We also examine statistically the
distribution of stars of different masses within clusters as a function of the
cluster age. Results: No significant dependence of the cluster size on location
in the Galaxy is detected for younger clusters (< 200 Myr), whereas older
clusters inside the solar orbit turned out to be, on average, smaller than
outside. Also, small old clusters are preferentially found close to the
Galactic plane, whereas larger ones more frequently live farther away from the
plane and at larger Galactocentric distances. For clusters with (V - M_V) <
10.5, a clear dependence of the apparent radius on age has been detected: the
cluster radii decrease by a factor of about 2 from an age of 10 Myr to an age
of 1 Gyr. A detailed analysis shows that this observed effect can be explained
by mass segregation and does not necessarily reflect a real decrease of cluster
radii. We found evidence for the latter for the majority of clusters older than
30 Myr. Among the youngest clusters (between 5 and 30 Myr), there are some
clusters with a significant grade of mass segregation, whereas some others show
no segregation at all. At a cluster age between 50 and 100 Myrs, the
distribution of stars of different masses becomes more regular over cluster
area. In older clusters the evolution of the massive stars is the most
prominent effect we observe.


title: Anti-Neutrino Imprint in Solar Neutrino Flare

abstract:
  Future neutrino detector at Megaton mass might enlarge the neutrino telescope
thresholds revealing cosmic supernova background and largest solar flares
neutrino. Indeed the solar energetic flare particles while scattering among
themselves on Solar corona atmosphere must produce prompt charged pions, whose
chain decays are source of solar (electron-muon) neutrino "flare" (at tens or
hundreds MeV energy). These brief (minutes) neutrino "burst" at largest flare
peak may overcome by three to five order of magnitude the steady atmospheric
neutrino noise on the Earth, possibly leading to their detection above
detection. Moreover the birth of anti-neutrinos at a few tens MeVs is well
loudly flaring above a null thermal "hep" anti-neutrino solar background and
also above a tiny supernova relic and atmospheric noise. The largest prompt
solar anti-neutrino "burst" may be well detected in future SuperKamikande
(Gadolinium implemented) by anti-neutrino signatures mostly in inverse Beta
decay. Our estimate for the recent and exceptional October - November 2003
solar flares and January 20th 2005 exceptional eruption might lead to a few
events above or near unity for existing Super-Kamiokande and above unity for
Megaton detectors. The neutrino spectra may reflect in a subtle way the
neutrino flavor oscillations and mixing in flight. A comparison of the solar
neutrino flare (at their birth place on Sun and after oscillation on the
arrival on the Earth) with other neutrino foreground is estimated: it offers an
independent track to disentangle the neutrino flavor puzzles and its most
secret mixing angles. The sharpest noise-free anti-neutrino imprint maybe its
first clean voice.


title:
Probing cosmological parameters with the CMB: Forecasts from full Monte
  Carlo simulations

abstract:
  The Fisher matrix formalism has in recent times become the standard method
for predicting the precision with which various cosmological parameters can be
extracted from future data. This approach is fast, and generally returns
accurate estimates for the parameter errors when the individual parameter
likelihoods approximate a Gaussian distribution. However, where Gaussianity is
not respected (due, for instance, to strong parameter degeneracies), the Fisher
matrix formalism loses its reliability. In this paper, we compare the results
of the Fisher matrix approach with those from Monte Carlo simulations. The
latter method is based on the publicly available CosmoMC code, but uses
synthetic realisations of data sets anticipated for future experiments. We
focus on prospective cosmic microwave background (CMB) data from the Planck
satellite, with or without CMB lensing information, and its implications for a
minimal cosmological scenario with eight parameters and an extended model with
eleven parameters. We show that in many cases, the projected sensitivities from
the Fisher matrix and the Monte Carlo methods differ significantly,
particularly in models with many parameters. Sensitivities to the neutrino mass
and the dark matter fraction are especially susceptible to change.


title: Generating the primordial curvature perturbations in preheating

abstract:
  We show that the primordial curvature perturbations may originate not from
the quantum fluctuations of inflaton during inflation but from isocurvature
perturbations which are amplified during preheating after inflation. We
consider a simple preheating model, whose potential is given by $V(\phi,
\chi)={1/4}\lambda \phi^4+{1/2}g^2 \phi^2 \chi^2$ with $g^2/\lambda=2$, as a
possible realization of generating curvature perturbations during preheating.
We make use of the $\delta N$ formalism which requires only knowledge of the
homogeneous background solutions in order to evaluate the evolution of
curvature perturbations on super-horizon scales. We solve the background
equations numerically and find that the amplitude and the spectral index of
curvature perturbations originating from preheating can be tuned to the
observed values if the isocurvature perturbations at the end of inflation is
not suppressed on super-horizon scales. We also point out that the tensor to
scalar ratio in ${1/4}\lambda \phi^4$ inflation model can be significantly
lowered, hence letting the ${1/4}\lambda \phi^4$ model, which is ruled out by
the Wilkinson Microwave Anisotropy Probe (WMAP) data combined with SDSS data,
get back into the observationally allowed region.


title:
First results of the Instrumentation Line for the deep-sea ANTARES
  neutrino telescope

abstract:
  In 2005, the ANTARES Collaboration deployed and operated at a depth of 2500 m
a so-called Mini Instrumentation Line equipped with Optical Modules (MILOM) at
the ANTARES site. The various data acquired during the continuous operation
from April to December 2005 of the MILOM confirm the satisfactory performance
of the Optical Modules, their front-end electronics and readout system, as well
as the calibration devices of the detector. The in-situ measurement of the
Optical Module time response yields a resolution better than 0.5 ns. The
performance of the acoustic positioning system, which enables the spatial
reconstruction of the ANTARES detector with a precision of about 10 cm, is
verified. These results demonstrate that with the full ANTARES neutrino
telescope the design angular resolution of better than $0.3^\circ$ can be
realistically achieved.


title:
An asymptotic decrease of (m_p/m_e) with cosmological time, from a
  decreasing, small effective vacuum expectation value moving from a potential
  maximum in the early universe

abstract:
  The empirical, possible small variation downward by about 10^-5, of the ratio
of the proton mass to the electron mass, over a characteristic time interval
estimated here to be about a billion years, is related to the decrease with
time of a small, effective vacuum expectation value for a Goldstone-like
pseudoscalar field which is present in the early universe, and is related to
the scalar inflaton field. The same vacuum expectation value controls the
magnitude of a very small, residual vacuum energy density today, which has also
slowly decreased. The present time variation is estimated to be near to a
definite limit, that is asymptotically approached as t->oo.


title: Helicity Observation of Weak and Strong Fields

abstract:
  We report in this letter our analysis of a large sample of photospheric
vector magnetic field measurements. Our sample consists of 17200 vector
magnetograms obtained from January 1997 to August 2004 by Huairou Solar
Observing Station of the Chinese National Astronomical Observatory. Two
physical quantities, $\alpha$ and current helicity, are calculated and their
signs and amplitudes are studied in a search for solar cycle variations.
Different from other studies of the same type, we calculate these quantities
for weak ($100G<|B_z|<500G$) and strong ($|B_z|>1000G$) fields separately. For
weak fields, we find that the signs of both $\alpha$ and current helicity are
consistent with the established hemispheric rule during most years of the solar
cycle and their magnitudes show a rough tendency of decreasing with the
development of solar cycle. Analysis of strong fields gives an interesting
result: Both $\alpha$ and current helicity present a sign opposite to that of
weak fields. Implications of these observations on dynamo theory and helicity
production are also briefly discussed.


title:
Spitzer observations of HH54 and HH7-11: mapping the H2 ortho-to-para
  ratio in shocked molecular gas

abstract:
  We report the results of spectroscopic mapping observations carried out
toward the Herbig-Haro objects HH7-11 and HH54 over the 5.2 - 37 micron region
using the Infrared Spectrograph of the Spitzer Space Telescope. These
observations have led to the detection and mapping of the S(0) - S(7) pure
rotational lines of molecular hydrogen, together with emissions in fine
structure transitions of Ne+, Si+, S, and Fe+. The H2 rotational emissions
indicate the presence of warm gas with a mixture of temperatures in the range
400 - 1200 K, consistent with the expected temperature behind nondissociative
shocks of velocity ~ 10 - 20 km/s, while the fine structure emissions originate
in faster shocks of velocity 35 - 90 km/s that are dissociative and ionizing.
Maps of the H2 line ratios reveal little spatial variation in the typical
admixture of gas temperatures in the mapped regions, but show that the H2
ortho-to-para ratio is quite variable, typically falling substantially below
the equilibrium value of 3 attained at the measured gas temperatures. The
non-equilibrium ortho-to-para ratios are characteristic of temperatures as low
as ~ 50 K, and are a remnant of an earlier epoch, before the gas temperature
was elevated by the passage of a shock. Correlations between the gas
temperature and H2 ortho-to-para ratio show that ortho-to-para ratios < 0.8 are
attained only at gas temperatures below ~ 900 K; this behavior is consistent
with theoretical models in which the conversion of para- to ortho-H2 behind the
shock is driven by reactive collisions with atomic hydrogen, a process which
possesses a substantial activation energy barrier (E_A/k ~ 4000 K) and is
therefore very inefficient at low temperature.


title: Be stars: one ring to rule them all?

abstract:
  Aims. We report theoretical spectral energy distributions (SEDs), Br$\gamma$
line profiles and visibilities for two scenarios that can explain the disk
dissipation of active hot stars an account for the transition from the Be to
the B spectroscopic phase. Methods. We use the SIMECA code to investigate these
two scenarios: the first one where the disk is formed by successive outbursts
of the central star. A low-density region is developing above the star and
slowly grows outward and forms a ring-like structure that will gradually
excavate the disk. The second one, where a slowly decreasing mass loss, for
instance due to a decrease of the radiative force through an opacity change at
the base of the photosphere, may also be responsible for the vanishing of the
circumstellar disk. Results. We obtain that a clear signature of the disk
dissipation following the ring scenario will be the disappearance of the high
velocity tails in the emission lines and a nearly constant peaks separation.
Moreover, we found that following the ring-like scenario the visibilities must
show an increasing second lobe, an increase of the value of the first zero and,
assuming an unresolved central star, a first zero of the visibility curves that
appends at shorter baselines as far as the disk is been excavate. We propose to
use the AMBER instrument on the VLTI to probe if the the ring scenario is the
one that rule the Be phenomenon.


title: Prototype development of the Integral-Field unit for VIRUS

abstract:
  VIRUS is a planned integral-field instrument for the Hobby-Eberly Telescope
(HET). In order to achieve a large field-of-view and high grasp at reasonable
costs, the approach is to replicate integral-field units (IFU) and medium sized
spectrographs many times. The Astrophysical Institute Potsdam (AIP) contributes
to VIRUS with the development and testing of the IFU prototype. This paper
describes the optomechanical design and the manufacture of the fiber-based IFU
subsystem. The initial VIRUS development aims to produce a prototype and to
measure its performance. Additionally, techniques will be investigated to allow
industrial replication of the highly specific fiber-bundle layout. This will be
necessary if this technique is to be applied to the next generation of even
larger astronomical instrumentation.


title: Neutrino detectors in ice: results and perspectives

abstract:
  The AMANDA neutrino detector has been in operation at the South Pole for
several years. A number of searches for extraterrestrial sources of high energy
neutrinos have been performed. A selection of results is presented in this
paper. The much larger IceCube detector will extend the instrumented ice volume
to a cubic kilometer and 9 out of 80 planned IceCube strings have been deployed
to date. We present the status for both detectors.


title:
Stellar Populations and Mass-Loss in M15: A Spitzer Detection of Dust in
  the Intra-Cluster Medium

abstract:
  We present Spitzer Space Telescope IRAC and MIPS observations of the galactic
globular cluster M15 (NGC 7078), one of the most metal-poor clusters with a
[Fe/H] = -2.4. Our Spitzer images reveal a population of dusty red giants near
the cluster center, a previously detected planetary nebula (PN) designated
K648, and a possible detection of the intra-cluster medium (ICM) arising from
mass loss episodes from the evolved stellar population. Our analysis suggests 9
(+/-2) x 10^-4 solar masses of dust is present in the core of M15, and this
material has accumulated over a period of approximately 10^6 years, a timescale
ten times shorter than the last galactic plane crossing event. We also present
Spitzer IRS follow up observations of K648, including the detection of the
[NeII] 12.81 micron line, and discuss abundances derived from infrared fine
structure lines.