title: Equation of state for Universe from similarity symmetries

abstract:
  In this paper we proposed to use the group of analysis of symmetries of the
dynamical system to describe the evolution of the Universe. This methods is
used in searching for the unknown equation of state. It is shown that group of
symmetries enforce the form of the equation of state for noninteracting scaling
multifluids. We showed that symmetries give rise the equation of state in the
form $p=-\Lambda+w_{1}\rho(a)+w_{2}a^{\beta}+0$ and energy density
$\rho=\Lambda+\rho_{01}a^{-3(1+w)}+\rho_{02}a^{\beta}+\rho_{03}a^{-3}$, which
is commonly used in cosmology. The FRW model filled with scaling fluid (called
homological) is confronted with the observations of distant type Ia supernovae.
We found the class of model parameters admissible by the statistical analysis
of SNIa data. We showed that the model with scaling fluid fits well to
supernovae data. We found that $\Omega_{\text{m},0} \simeq 0.4$ and $n \simeq
-1$ ($\beta = -3n$), which can correspond to (hyper) phantom fluid, and to a
high density universe. However if we assume prior that
$\Omega_{\text{m},0}=0.3$ then the favoured model is close to concordance
$\Lambda$CDM model. Our results predict that in the considered model with
scaling fluids distant type Ia supernovae should be brighter than in
$\Lambda$CDM model, while intermediate distant SNIa should be fainter than in
$\Lambda$CDM model. We also investigate whether the model with scaling fluid is
actually preferred by data over $\Lambda$CDM model. As a result we find from
the Akaike model selection criterion prefers the model with noninteracting
scaling fluid.


title:
The enigmatic B[e]-star Henize 2-90: The non-spherical mass loss history
  from an analysis of forbidden lines

abstract:
  (abridged) We study the optical spectrum of the exciting B[e] star Hen 2-90
based on new high-resolution observations that cover the innermost 2". Our
investigation is splitted in two parts, a qualitative study of the presence of
the numerous emission lines and the classification of their line profiles which
indicate a circumstellar environment of high complexity, and a quantitative
analysis of numerous forbidden lines, e.g. [OI], [OII], [OIII], [SII], [SIII],
[ArIII], [ClII], [ClIII] and [NII]. We find a correlation between the different
ionization states of the elements and the velocities derived from the line
profiles: the highly ionized atoms have the highest outflow velocity while the
neutral lines have the lowest outflow velocity. The recent HST image of Hen
2-90 reveals a bipolar, highly ionized region, a neutral disk-like structure
and an intermediate region of moderate ionization. It seems that a
non-spherical stellar wind model is a good option to explain the ionization and
spatial distribution of the circumstellar material. We modelled the forbidden
lines under the assumption of a non-spherically symmetric wind based on the HST
image. We find that in order to fit the observed line luminosities, the mass
flux, surface temperature, and terminal wind velocities need to be latitude
dependent, which might be explained in terms of a rapidly rotating central
star. A rotation speed of 75-80 % of the critical velocity has been derived.
The total mass loss rate of the star was determined to be of order 3 10^{-5}
M_sun/yr. Such a wind scenario and the fact that compared to solar abundances
C, O, and N seem to be underabundant while S, Ar and Cl have solar abundances,
might be explained in terms of a rapidly rotating post-AGB star.


title:
Tests of a Prototype Multiplexed Fiber-Optic Ultra-fast FADC Data
  Acquisition System for the MAGIC Telescope

abstract:
  Ground-based Atmospheric Air Cherenkov Telescopes (ACTs) are successfully
used to observe very high energy (VHE) gamma rays from celestial objects. The
light of the night sky (LONS) is a strong background for these telescopes. The
gamma ray pulses being very short, an ultra-fast read-out of an ACT can
minimize the influence of the LONS. This allows one to lower the so-called tail
cuts of the shower image and the analysis energy threshold. It could also help
to suppress other unwanted backgrounds.
  Fast 'flash' analog-to-digital converters (FADCs) with GSamples/s are
available commercially; they are, however, very expensive and power consuming.
Here we present a novel technique of Fiber-Optic Multiplexing which uses a
single 2 GSamples/s FADC to digitize 16 read-out channels consecutively. The
analog signals are delayed by using optical fibers. The multiplexed (MUX) FADC
read-out reduces the cost by about 85% compared to using one ultra-fast FADC
per read-out channel.
  Two prototype multiplexers, each digitizing data from 16 channels, were built
and tested. The ultra-fast read-out system will be described and the test
results will be reported. The new system will be implemented for the read-out
of the 17m diameter MAGIC telescope camera.


title: Astrometric Discovery of GJ 802b: In the Brown Dwarf Oasis?

abstract:
  The Stellar Planet Survey is an ongoing astrometric search for giant planets
and brown dwarfs around a sample of about 30 M-dwarfs. We have discovered
several low-mass companions by measuring the motion of our target stars
relative to their reference frames. The lowest mass discovery thus far is GJ
802b, a companion to the M5-dwarf GJ 802A. The orbital period is 3.14 +/- 0.03
y, the system mass is 0.214 +/- 0.045 Msolar, and the semi-major axis is 1.28
+/- 0.10 AU or 81 +/- 6 mas. Imaging observations indicate that GJ 802b is
likely to be a brown dwarf with the astrometrically determined mass 0.058 +/-
0.021 Msolar (one sigma limits). The remaining uncertainty in the orbit is the
eccentricity that is now loosely constrained. We discuss how the system age
limits the mass and the prospects to further narrow the mass range when e is
more precisely determined.


title: Relativistic Aberration Effect in Astrophysics and Cosmology

abstract:
  Relativistic aberration influences apparent luminosities of objects moving
with relativistic relative velocities. The superluminosity or dimming of
incoming or receding jets ejected from Active Galactic Nuclei is believed to be
the manifestation of the effect. Redshifted cosmological objects, such as
high-z galaxies and supernovae in high-z galaxies, are also subjected to
luminosity dimming due to relativistic aberration, although the correcting
terms encompassing spectral redshift and time dilation are used to scale the
observed magnitudes in the restframe template. The Universe's expansion results
in elongation of distances to the objects from the moment of emission to the
present time related to the z = 0 local space; this elongation is equal to the
apparent increase of the distance from the apparent size to the restframe
distance in the theory of special relativity due to the effect of relativistic
aberration. Contrary to the standard Big Bang model with stationary space, the
effect of relativistic aberration zeroes in the expending space model; if local
spaces and local objects expand together with the Universe, the luminosity
distances to high-redshifted objects appear to be smaller then in the Big Bang
model.


title: Haloes of k-Essence

abstract:
  We study gravitationally bound static and spherically symmetric
configurations of k-essence fields. In particular, we investigate whether these
configurations can reproduce the properties of dark matter haloes. The classes
of Lagrangians we consider lead to non-isotropic fluids with barotropic and
polytropic equations of state. The latter include microscopic realizations of
the often-considered Chaplygin gases, which we find can cluster into dark
matter halo-like objects with flat rotation curves, while exhibiting a dark
energy-like negative pressure on cosmological scales. We complement our studies
with a series of formal general results about the stability and initial value
formulation of non-canonical scalar field theories, and we also discuss a new
class of de Sitter solutions with spacelike field gradients.


title:
Characterizing the Adaptive Optics Off-Axis Point-Spread Function. II.
  Methods for Use in Laser Guide Star Observations

abstract:
  Most current astronomical adaptive optics (AO) systems rely on the
availability of a bright star to measure the distortion of the incoming
wavefront. Replacing the guide star with an artificial laser beacon alleviates
this dependency on bright stars and therefore increases sky coverage, but it
does not eliminate another serious problem for AO observations. This is the
issue of PSF variation with time and field position near the guide star. In
fact, because a natural guide star is still necessary for correction of the
low-order phase error, characterization of laser guide star (LGS) AO PSF
spatial variation is more complicated than for a natural guide star alone. We
discuss six methods for characterizing LGS AO PSF variation that can
potentially improve the determination of the PSF away from the laser spot, that
is, off-axis. Calibration images of dense star fields are used to determine the
change in PSF variation with field position. This is augmented by AO system
telemetry and simple computer simulations to determine a more accurate off-axis
PSF. We report on tests of the methods using the laser AO system on the Lick
Observatory Shane Telescope. [Abstract truncated.]


title:
Stellar Content from high resolution galactic spectra via Maximum A
  Posteriori

abstract:
  This paper describes STECMAP (STEllar Content via Maximum A Posteriori), a
flexible, non-parametric inversion method for the interpretation of the
integrated light spectra of galaxies, based on synthetic spectra of single
stellar populations (SSPs). We focus on the recovery of a galaxy's star
formation history and stellar age-metallicity relation. We use the high
resolution SSPs produced by PEGASE-HR to quantify the informational content of
the wavelength range 4000 - 6800 Angstroms.
  A detailed investigation of the properties of the corresponding simplified
linear problem is performed using singular value decomposition. It turns out to
be a powerful tool for explaining and predicting the behaviour of the
inversion. We provide means of quantifying the fundamental limitations of the
problem considering the intrinsic properties of the SSPs in the spectral range
of interest, as well as the noise in these models and in the data.
  We performed a systematic simulation campaign and found that, when the time
elapsed between two bursts of star formation is larger than 0.8 dex, the
properties of each episode can be constrained with a precision of 0.04 dex in
age and 0.02 dex in metallicity from high quality data (R=10 000,
signal-to-noise ratio SNR=100 per pixel), not taking model errors into account.
  The described methods and error estimates will be useful in the design and in
the analysis of extragalactic spectroscopic surveys.


title:
A Possible Correlation Between the Luminosities and Lifetimes of Active
  Galactic Nuclei

abstract:
  We use the clustering of galaxies around distant AGN to show with ~90%
confidence that fainter AGN are longer lived. Our argument is simple: since the
measured galaxy-AGN cross-correlation length r_0 ~ 5h^-1 Mpc does not vary
significantly over a 10 magnitude range in AGN optical luminosity, faint and
bright AGN must reside in dark matter halos with similar masses. The halos that
host bright and faint AGN therefore have similar intrinsic abundances, and the
large observed variation in AGN number density with luminosity reflects a
change in duty cycle.


title: Galaxy Morphology - Halo Gas Connections

abstract:
  We studied a sample of 38 intermediate redshift MgII absorption-selected
galaxies using (1) Keck/HIRES and VLT/UVES quasar spectra to measure the halo
gas kinematics from MgII absorption profiles and (2) HST/WFPC-2 images to study
the absorbing galaxy morphologies. We have searched for correlations between
quantified gas absorption properties, and host galaxy impact parameters,
inclinations, position angles, and quantified morphological parameters. We
report a 3.2-sigma correlation between asymmetric perturbations in the host
galaxy morphology and the MgII absorption equivalent width. We suggest that
this correlation may indicate a connection between past merging and/or
interaction events in MgII absorption-selected galaxies and the velocity
dispersion and quantity of gas surrounding these galaxies.


title: A Search For Organic Molecules in Intermediate Redshift DLAs

abstract:
  There has been a renewed interest in searching for diffuse interstellar bands
(DIBs) due to their probable connection to organic molecules and, thus, their
possible link to life in the Universe. Our group is undertaking an extensive
search for DIBs in DLAs via QSO absorption-line systems. Six of our DLA targets
are presented here. Our equivalent width (EW) limits for the 5780 DIB line
strongly suggests that DIB abundance is below the Milky Way expected value or
that metallicity plays a large role in DIB strengths.


title:
Hybrid Characteristics: 3D radiative transfer for parallel adaptive mesh
  refinement hydrodynamics

abstract:
  We have developed a three-dimensional radiative transfer method designed
specifically for use with parallel adaptive mesh refinement hydrodynamics
codes. This new algorithm, which we call hybrid characteristics, introduces a
novel form of ray tracing that can neither be classified as long, nor as short
characteristics, but which applies the underlying principles, i.e. efficient
execution through interpolation and parallelizability, of both. Primary
applications of the hybrid characteristics method are radiation hydrodynamics
problems that take into account the effects of photoionization and heating due
to point sources of radiation. The method is implemented in the hydrodynamics
package FLASH. The ionization, heating, and cooling processes are modelled
using the DORIC ionization package. Upon comparison with the long
characteristics method, we find that our method calculates the column density
with a similarly high accuracy and produces sharp and well defined shadows. We
show the quality of the new algorithm in an application to the photoevaporation
of multiple over-dense clumps. We present several test problems demonstrating
the feasibility of our method for performing high resolution three-dimensional
radiation hydrodynamics calculations that span a large range of scales. Initial
performance tests show that the ray tracing part of our method takes less time
to execute than other parts of the calculation (e.g. hydrodynamics and adaptive
mesh refinement), and that a high degree of efficiency is obtained in parallel
execution. Although the hybrid characteristics method is developed for problems
involving photoionization due to point sources, the algorithm can be easily
adapted to the case of more general radiation fields.


title:
Radial Velocity Jitter in Stars from the California and Carnegie Planet
  Search at Keck Observatory

abstract:
  I present an empirical model for predicting a star's radial velocity jitter
from its B-V color, activity level, and absolute magnitude. This model is based
on observations of 450 well- observed stars from Keck Observatory for the
California and Carnegie Planet Search Program. The model includes noise from
both astrophysical sources and systematic errors, and describes jitter as
generally increasing with a star's activity and height above the main sequence.


title:
A Resonance Model of Quasi-Periodic Oscillations of Low-Mass X-Ray
  Binaries

abstract:
  We try to understand the quasi-periodic oscillations (QPOs) in low-mass
neutron-star and black-hole X-ray binaries by a resonance model in warped disks
with precession. Our main concern is high-frequency QPOs, hectohertz QPOs, and
horizontal-branch QPOs in the z sources and the atoll sources, and the
correponding QPOs in black-hole X-ray binaries. Our resonance model can
qualitatively, but systematically, explain these QPOs by regarding hectohertz
QPOs as a precession of warp.


title: Anti-Truncation of Disks in Early-Type Barred Galaxies

abstract:
  The disks of spiral galaxies are commonly thought to be truncated: the radial
surface brightness profile steepens sharply beyond a certain radius (3--5
inner-disk scale lengths). Here we present the radial brightness profiles of a
number of barred S0--Sb galaxies with the opposite behavior: their outer
profiles are distinctly shallower in slope than the main disk profile. We term
these "anti-truncations"; they are found in at least 25% of a larger sample of
barred S0--Sb galaxies. There are two distinct types of anti-truncations. About
one-third show a fairly gradual transition and outer isophotes which are
progressively rounder than the main disk isophotes, suggestive of a disk
embedded within a more spheroidal outer zone -- either the outer extent of the
bulge or a separate stellar halo. But the majority of the profiles have rather
sharp surface-brightness transitions to the shallower, outer exponential
profile and, crucially, outer isophotes which are not significantly rounder
than the main disk; in the Sab--Sb galaxies, the outer isophotes include
visible spiral arms. This suggests that the outer light is still part of the
disk. A subset of these profiles are in galaxies with asymmetric outer
isophotes (lopsided or one-armed spirals), suggesting that interactions may be
responsible for at least some of the disklike anti-truncations.


title:
Radio Observations of the Hubble Deep Field South region: I. Survey
  Description and Initial Results

abstract:
  This paper is the first of a series describing the results of the Australia
Telescope Hubble Deep Field South (ATHDFS) radio survey. The survey was
conducted at four wavelengths - 20, 11, 6, and 3 cm, over a 4-year period, and
achieves an rms sensitivity of about 10 microJy at each wavelength. We describe
the observations and data reduction processes, and present data on radio
sources close to the centre of the HDF-S. We discuss in detail the properties
of a subset of these sources. The sources include both starburst galaxies and
galaxies powered by an active galactic nucleus, and range in redshift from 0.1
to 2.2. Some of them are characterised by unusually high radio-to-optical
luminosities, presumably caused by dust extinction.


title:
Accretion by the Secondary in Eta Carinae During the Spectroscopic
  Event: I. Flow Parameters

abstract:
  We examine the influence of the gravity of the companion (the secondary) to
the massive primary star Eta Carinae on the winds blown by the primary and the
secondary. The two winds collide with each other after passing through two
respective shock waves, and escape the system while strongly emitting in the
X-ray band. While during most of the 5.5 years orbital period, the companion's
gravity has a negligible effect on the winds, we find that near periastron, the
companion's gravity may significantly influence the flow and the companion
might accrete from the primary's wind under certain circumstances. Near
periastron passage, the collision region of the two winds may collapse onto the
secondary star, a process that could substantially reduce the X-ray luminosity.
We suggest that such an accretion process produces the long, almost flat, X-ray
minimum in Eta Carinae.


title:
Serendipitous discovery of the unidentified extended TeV gamma-ray
  source HESS J1303-631

abstract:
  The serendipitous discovery of an unidentified extended TeVgamma-ray source
close to the galactic plane named HESS J1303-631 at a significance of 21
standard deviations is reported. The observations were performed between
February and June 2004 with the H.E.S.S. stereoscopic system of Cherenkov
telescopes in Namibia. HESS J1303-631 was discovered roughly 0.6 deg north of
the binary system PSR B1259-63/SS 2883, the target object of the initial
observation campaign which was also detected at TeV energies in the same field
of view. HESS J1303-631 is extended with a width of an assumed intrinsic
Gaussian emission profile of sigma = (0.16 +- 0.02) deg and the integral flux
above 380 GeV is compatible with constant emission over the entire
observational period of (17 +- 3)% of the Crab Nebula flux. The measured energy
spectrum can be described by a power-law dN/dE ~ E^-Gamma with a photon index
of Gamma = 2.44 +- 0.05_stat +- 0.2_syst. Up to now, no counterpart at other
wavelengths is identified. Various possible TeV production scenarios are
discussed.


title: Ultra High Energy Neutrino Astronomy

abstract:
  The short review of theoretical aspects of ultra high energy (UHE) neutrinos
and superGZK neutrinos. The sources and diffuse fluxes of UHE neutrinos are
discussed. Much attention is given to comparison of the cascade and cosmic ray
upper bounds for diffuse neutrino fluxes. Cosmogenic neutrinos and neutrinos
from the mirror mater are considered as superGZK neutrinos.


title:
Full computation of massive AGB evolution. II. The role of mass loss and
  cross-sections

abstract:
  In the course of a systematic exploration of the uncertainties associated to
the input micro- and macro-physics in the modeling of the evolution of
intermediate mass stars during their Asymptotic Giant Branch (AGB) phase, we
focus on the role of the nuclear reactions rates and mass loss. We consider
masses 3<M/Msun<6.5 for a metallicity typical for Globular Cluster, Z=0.001,
and compare the results obtained by computing the full nucleosynthesis with hot
bottom burning (HBB), for a network of 30 elements, using either the NACRE or
the Cameron & Fowler (1988) cross-sections. The results differ in particular
with respect to the Na23 nucleosynthesis (which is more efficient in the NACRE
case) and the magnesium isotopes ratios. For both choices, however, the CNO
nucleosynthesis shows that the C+N+O is constant within a factor of two, in our
models employing a very efficient convection treatment. Different mass loss
rates alter the physical conditions for HBB and the length of the AGB phase,
changing indirectly the chemical yields. These computations show that the
predictive power of our AGB models is undermined by these uncertainties. In
particular, it appears at the moment very difficult to strongly accept or
dismiss that these sources play a key-role in the pollution of Globular
Clusters (GCs)


title:
New model of angular momentum transfer from the rotating central body of
  a two-body system into the orbital motion of this system (with application to
  the earth-moon system)

abstract:
  In a previous paper we treated within the framework of our Projective Unified
Field Theory (Schmutzer 2004, Schmutzer 2005a) the 2-body system (e.g.
earth-moon system) with a rotating central body in a rather abstract manner.
Here a concrete model of the transfer of angular momentum from the rotating
central body to the orbital motion of the whole 2-body system is presented,
where particularly the transfer is caused by the inhomogeneous gravitational
force of the moon acting on the oceanic waters of the earth, being modeled by a
spherical shell around the solid earth. The theory is numerically tested. Key
words: transfer of angular momentum from earth to moon, action of the
gravitational force of the moon on the waters of the earth.


title: RRAB Variables and Metallicity

abstract:
  A preliminary analysis of the UBV light curves of RR AB variables revealed
that they contain information on the metallicities of these stars. The computed
parameters which correlate with metallicity are given in the tables for 99 RR
AB stars including 12 variables without previously determined metallicities.


title:
W Hya through the eye of Odin Satellite observations of circumstellar
  submillimetre H$_2$O line emission

abstract:
  We present Odin observations of the AGB star W Hya in the ground-state
transition of ortho-H2O, 1(10)-1(01), at 557GHz. The line is clearly of
circumstellar origin. Radiative transfer modelling of the water lines observed
by Odin and ISO results in a mass-loss rate of (2.5 +/- 0.5)E-7 Msol/yr, and a
circumstellar H2O abundance of (2.0 +/- 1.0)E-3. The inferred mass-loss rate is
consistent with that obtained from modelling the circumstellar CO radio line
emission, and also with that obtained from the dust emission modelling combined
with a dynamical model for the outflow. The very high water abundance, higher
than the cosmic oxygen abundance, can be explained by invoking an injection of
excess water from evaporating icy bodies in the system. The required extra mass
of water is quite small, on the order of ~ 0.1 earth mass.


title:
The detection of Class I methanol masers towards regions of low-mass
  star formation

abstract:
  Six young bipolar outflows in regions of low-to-intermediate-mass star
formation were observed in the 7_0-6_1A+, 8_0-7_1A+, and 5_{-1}-4_0E methanol
lines at 44, 95, and 84 GHz, respectively. Narrow features were detected
towards NGC 1333IRAS4A, HH 25MMS, and L1157 B1. Flux densities of the detected
lines are no higher than 11 Jy, which is much lower than the flux densities of
strong maser lines in regions of high-mass star formation. Analysis shows that
most likely the narrow features are masers.


title: The mass of dwarf spheroidal galaxies and the missing satellite problem

abstract:
  We present the results from a suite of N-body simulations of the tidal
stripping of two-component dwarf galaxies comprising some stars and dark
matter. We show that recent kinematic data from the local group dwarf
spheroidal (dSph) galaxies suggests that dSph galaxies must be sufficiently
massive ($10^9 - 10^{10}$M$_\odot$) that tidal stripping is of little
importance for the stars. We discuss the implications of these massive dSph
galaxies for cosmology and galaxy formation.


title: Spectroscopic binaries with elliptical orbits

abstract:
  The radial velocity curves of many spectroscopic binaries (SBs) are perturbed
by gas streams or proximity effects. For SBs with circular orbits, these
perturbations can give rise to spurious orbital eccentricities of high
statistical significance. But tests to identify such anomalous orbits can be
constructed since perturbed velocity curves are in general no longer Keplerian.
The derived tests are applied both to synthetic and to observed velocity
curves.


title:
A feasibility study of future observations with MIDI and other VLTI
  science instruments: The example of the Galactic Center

abstract:
  VLT-Interferometry will allow imaging of the Galactic Center (GC) and the
nuclei of extragalactic sources at an angular resolution of a few
milliarcseconds. VLTI will be a prime instrument to study the immediate
environment of the massive black hole at the center of the Milky Way. With the
MID infrared Interferometric instrument (MIDI) for example the enigmatic
compact dust embedded MIR-excess sources within the central parsec should be
resolvable. Further the observations of external galactic nuclei will allow
unprecedented measurements of physical parameters (i.e. structure and
luminosity) in these systems. With the exception of a few 'self-referencing'
sources these faint-target observations will benefit from the available
off-axis wavefront-correction system. To fully exploit the use of VLTI within
this context, the following questions have to be addressed among others: How
feasible is blind-pointing on (faint) science targets? Are VLTI observations
still efficiently feasible if these faint science targets exceed the usual
angular distance (<=1arcmin) to a GuideStar [...]? How is the fringe-tracking
procedure affected in densely populated regions such as the GC? What
preparatory steps have to be performed to successfully observe these
non-standard targets with the VLTI? In this contribution, we present aspects
for the preparation of VLTI observations, which will be conducted in the near
future. Considering these example observations of the GC region, several
details of observing modes are discussed, which are necessary to observe such
science targets. The final goal is the definition of observational strategies
[...] touching the limits of VLTI observability.


title:
Hydrodynamical stellar models including rotation, internal gravity waves
  and atomic diffusion. I. Formalism and tests on Pop I dwarfs

abstract:
  In this paper, we develop a formalism in order to incorporate the
contribution of internal gravity waves to the transport of angular momentum and
chemicals over long time-scales in stars. We show that the development of a
double peaked shear layer acts as a filter for waves, and how the asymmetry of
this filter produces momentum extraction from the core when it is rotating
faster than the surface. Using only this filtered flux, it is possible to
follow the contribution of internal waves over long (evolutionary) time-scales.
  We then present the evolution of the internal rotation profile using this
formalism for stars which are spun down via magnetic torquing. We show that
waves tend to slow down the core, creating a "slow" front that may then
propagate from the core to the surface. Further spin down of the surface leads
to the formation of a new front. Finally we show how this momentum transport
reduces rotational mixing in a 1.2Msun, Z=0.02 model, leading to a surface
lithium abundance in agreement with observations in the Hyades.


title:
Gravitomagnetic Effects on Collective Plasma Oscillations in Compact
  Stars

abstract:
  The effects of gravitomagnetic force on plasma oscillations are investigated
using the kinetic theory of homogeneous electrically neutral plasma in the
absence of external electric or magnetic field. The random phase assumption is
employed neglecting the thermal motion of the electrons with respect to a fixed
ion background. It is found that the gravitomagnetic force reduces the
characteristic frequency of the plasma thus enhancing the refractive index of
the medium. The estimates for the predicted effects are given for a typical
white dwarf, pulsar, and neutron star.


title: Discovery of Pulsed OH Maser Emission Stimulated by a Pulsar

abstract:
  Stimulated emission of radiation has not been directly observed in
astrophysical situations up to this time. Here we demonstrate that photons from
pulsar B1641-45 stimulate pulses of excess 1720 MHz line emission in an
interstellar OH cloud. As this stimulated emission is driven by the pulsar, it
varies on a few millisecond timescale, orders of magnitude shorter than the
quickest OH maser variations previously detected.
  Our 1612 MHz spectra are inverted copies of the 1720 MHz spectra. This
"conjugate line" phenomenon enables us to constrain the properties of the
interstellar OH line-producing gas.
  We also show that pulsar signals suffer significantly deeper OH absorption
than do other background sources; confirming earlier tentative findings that OH
clouds are clumpier on small scales than neutral hydrogen clouds.


title: Reply to comments of Dikpati et al

abstract:
  We present here our response to Dikpati et al.'s criticism of our recent
solar dynamo model.


title:
Neutrino emission in the hadronic Synchrotron Mirror Model: the "orphan"
  TeV flare from 1ES 1959+650

abstract:
  A challenge to standard leptonic SSC models are so-called orphan TeV flares,
i.e. enhanced very high energy (VHE) gamma-ray emission without any
contemporaneous X-ray flaring activity, that have recently been observed in
TeV-blazars (e.g., 1ES 1959+650). In order to explain the orphan TeV flare of
1ES 1959+650 observed in June 2002, the co-called hadronic synchrotron mirror
model has been developed. Here, relativistic protons are proposed to exist in
the jet, and interact with reflected electron-synchrotron radiation of the
precursor SSC flare. If the reflector is located in the cloud region, time
shifts of several days are possible between the precursor and the orphan flare.
The external photons, blueshifted in the comoving jet frame, are able to excite
the \Delta(1232)-resonance when interacting with protons of Lorentz factors
\gamma'_p~10^3-10^4. The decay products of this resonance include charged pions
which, upon decay, give rise to neutrino production during the orphan flare. In
this paper we calculate the expected neutrino emission for the June 4, 2002,
orphan TeV flare of 1ES 1959+650. We compare our results with the recent
observations of AMANDA-II of a neutrino event in spatial and temporal
coincidence with the orphan flare of this blazar. We find that the expected
neutrino signal from the hadronic synchrotron mirror model is insufficient to
explain the observed neutrino event from the direction of 1ES 1959+650.


title:
Giant Planet Migration through the Action of Disk Torques and Planet
  Scattering

abstract:
  This paper presents a parametric study of giant planet migration through the
combined action of disk torques and planet-planet scattering. The torques
exerted on planets during Type II migration in circumstellar disks readily
decrease the semi-major axes, whereas scattering between planets increases the
orbital eccentricities. This paper presents a parametric exploration of the
possible parameter space for this migration scenario using two (initial)
planetary mass distributions and a range of values for the time scale of
eccentricity damping (due to the disk). For each class of systems, many
realizations of the simulations are performed in order to determine the
distributions of the resulting orbital elements of the surviving planets; this
paper presents the results of 8500 numerical experiments. Our goal is to study
the physics of this particular migration mechanism and to test it against
observations of extrasolar planets. The action of disk torques and
planet-planet scattering results in a distribution of final orbital elements
that fills the a-e plane, in rough agreement with the orbital elements of
observed extrasolar planets. In addition to specifying the orbital elements, we
characterize this migration mechanism by finding the percentages of ejected and
accreted planets, the number of collisions, the dependence of outcomes on
planetary masses, the time spent in 2:1 and 3:1 resonances, and the effects of
the planetary IMF. We also determine the distribution of inclination angles of
surviving planets and the distribution of ejection speeds for exiled planets.


title: Constraints on the Orbital Evolution of Triton

abstract:
  We present simulations of Triton's post-capture orbit that confirm the
importance of Kozai-type oscillations in its orbital elements. In the context
of the tidal orbital evolution model, these variations require average
pericenter distances much higher than previously published, and the timescale
for the tidal orbital evolution of Triton becomes longer than the age of the
Solar System. Recently-discovered irregular satellites present a new constraint
on Triton's orbital history. Our numerical integrations of test particles
indicate a timescale for Triton's orbital evolution to be less than $10^5$ yrs
for a reasonable number of distant satellites to survive Triton's passage. This
timescale is inconsistent with the exclusively tidal evolution (time scale of
$>10^8$ yrs), but consistent with the interestion with the debris from
satellite-satellite collisions. Any major regular satellites will quickly
collide among themselves after being perturbed by Triton, and the resulting
debris disk would eventually be swept up by Triton; given that the total mass
of the Uranian satellite system is 40% of that of Triton, large scale evolution
is possible. This scenario could have followed either collisional or the
recently-discussed three-body-interaction-based capture.


title: The Effects of Gravitational Back-Reaction on Cosmological Perturbations

abstract:
  Because of the non-linearity of the Einstein equations, the cosmological
fluctuations which are generated during inflation on a wide range of
wavelengths do not evolve independently. In particular, to second order in
perturbation theory, the first order fluctuations back-react both on the
background geometry and on the perturbations themselves. I this paper, the
gravitational back-reaction of long wavelength (super-Hubble) scalar metric
fluctuations on the perturbations themselves is investigated for a large class
of inflationary models. Specifically, the equations describing the evolution of
long wavelength cosmological metric and matter perturbations in an inflationary
universe are solved to second order in both the amplitude of the perturbations
and in the slow roll expansion parameter. Assuming that the linear fluctuations
have random phases, we show that the fractional correction to the power
spectrum due to the leading infrared back-reaction terms does not change the
shape of the spectrum. The amplitude of the effect is suppressed by the product
of the inflationary slow-roll parameter and the amplitude of the linear power
spectrum. The non-gaussianity of the spectrum induced by back-reaction is
commented upon.


title: Results of a Search for Cold Flows of Dark Matter Axions

abstract:
  Theoretical arguments predict that the distribution of cold dark matter in
spiral galaxies has peaks in velocity space associated with non-thermalized
flows of dark matter particles. We searched for the corresponding peaks in the
spectrum of microwave photons from axion to photon conversion in the cavity
detector of dark matter axions. We found none and place limits on the density
of any local flow of axions as a function of the flow velocity dispersion over
the axion mass range 1.98 to 2.17 $\mu$eV.


title: Neutrino emission rates in highly magnetized neutron stars revisited

abstract:
  Magnetars are a subclass of neutron stars whose intense soft-gamma-ray bursts
and quiescent X-ray emission are believed to be powered by the decay of a
strong internal magnetic field. We reanalyze neutrino emission in such stars in
the plausibly relevant regime in which the Landau band spacing of both protons
and electrons is much larger than kT (where k is the Boltzmann constant and T
is the temperature), but still much smaller than the Fermi energies. Focusing
on the direct Urca process, we find that the emissivity oscillates as a
function of density or magnetic field, peaking when the Fermi level of the
protons or electrons lies about 3kT above the bottom of any of their Landau
bands. The oscillation amplitude is comparable to the average emissivity when
the Landau band spacing mentioned above is roughly the geometric mean of kT and
the Fermi energy (excluding mass), i. e., at fields much weaker than required
to confine all particles to the lowest Landau band. Since the density and
magnetic field strength vary continuously inside the neutron star, there will
be alternating surfaces of high and low emissivity. Globally, these
oscillations tend to average out, making it unclear whether there will be any
observable effects.


title:
Early BVRcIc imaging and the discovery of the optical afterglow of GRB
  041218

abstract:
  We report early BVRcIc imaging of the INTEGRAL GRB 041218. The observation
started 129 s after the burst and a sequence of exposures in V, Rc, Ic, and B
bands were repeated. The optical afterglow is detected in Rc and Ic bands while
it was not detected in B and V. We find that the early afterglow deviates from
a single power law decay and identify two characteristic timescales (breaks).
Such breaks are theoretically expected from synchrotron cooling in the
relativistic fireball (Sari et al. 1998) and we crudely constrain the physical
condition of the relativistic shock.


title:
Simultaneous Flavor Transformation of Neutrinos and Antineutrinos with
  Dominant Potentials from Neutrino-Neutrino Forward Scattering

abstract:
  In astrophysical environments with intense neutrino fluxes, neutrino-neutrino
forward scattering contributes both diagonal and off-diagonal potentials to the
flavor-basis Hamiltonian that governs neutrino flavor evolution. We examine a
special case where adiabatic flavor evolution can produce an off-diagonal
potential from neutrino-neutrino forward scattering that dominates over both
the corresponding diagonal term and the potential from neutrino-matter forward
scattering. In this case, we find a solution that, unlike the ordinary
Mikeyhev-Smirnov-Wolfenstein scenario, has both neutrinos and antineutrinos
maximally mixed in medium over appreciable ranges of neutrino and antineutrino
energy. Employing the measured solar and atmospheric neutrino mass-squared
differences, we identify the conditions on neutrino fluxes that are required
for this solution to exist deep in the supernova environment, where it could
affect the neutrino signal, heavy-element nucleosynthesis, and even the revival
of the supernova shock. We speculate on how this solution might or might not be
attained in realistic supernova evolution. Though this solution is ephemeral in
time and/or space in supernovae, it may signal the onset of subsequent
appreciable flavor mixing for both neutrinos and antineutrinos. A similar
solution may also exist in an early universe with significant net
neutrino-lepton numbers.


title:
X-Ray Emission and Optical Polarization of V1432 Aquilae: An
  Asynchronous Polar

abstract:
  A detailed analysis of X-ray data from ROSAT, ASCA, XMM and RXTE for the
asynchronous polar V1432 Aql along with Stokes polarimetry data from SAAO, is
presented. Power spectra from long-baseline ROSAT data show a spin period of
12150s along with several system related frequency components. However, the
second harmonic of the spin period dominates power spectrum in the XMM data.
For the optical circular polarization, the dominant period corresponds to half
the spin period. The ROSAT data can be explained as due to accretion onto two
hot spots that are not anti-podal. The variations seen in the optical
polarization and the ASCA and XMM data suggest the presence of at least three
accretion foot prints on the white dwarf surface. Two spectral models, a
multi-temperature plasma and a photo-ionized plasma model, are used for
spectral study. The RXTE PCA data are used to constrain the white dwarf mass to
1.2$\pm$0.1 M_odot using the multi-temperature plasma model. A strong soft
X-ray excess (<0.8 keV) in the XMM MOS data is well modeled by a blackbody
component having a temperature of 80-90 eV. The plasma emission lines seen at
6.7 and 7.0 keV are well fitted using the multi-temperature plasma model,
however an additional Gaussian is needed for the 6.4 keV line. The
multi-temperature plasma model requires a homogeneous absorber fully covering
the source and a partial absorber covering 65% of the source. The photo-ionized
plasma model, with a range of Fe column densities, gives a slightly better
overall fit and fits all emission lines. The presence of a strong blackbody
component, a spin period of 12150s, modulation of the 6.4 keV line flux with
spin period, and a very hard X-ray component suggest that V1432 Aql is a polar
with X-ray spectral properties similar to that of a soft intermediate polar.


title: Three active M dwarfs within 8 pc: L 449-1, L 43-72, & LP 949-15

abstract:
  Three nearby star candidates were selected as bright 2MASS point sources
without associated optical sources, i.e. with potentially large proper motions,
subsequently confirmed by multi-epoch optical data from the SuperCOSMOS Sky
Surveys. All three objects are listed in the NLTT catalogue of high proper
motion stars. Follow-up spectroscopic observations allowed us to classify L
449-1 as M4.0e dwarf at 5.7 pc, L43-72 as M4.5e dwarf at 7.2 pc, and LP 949-15
as M5.0e dwarf at 6.1 pc, using known absolute $JHK_\mathrm{s}$ magnitudes of
dwarfs with corresponding spectral types, respectively. All three stars exhibit
$H{\alpha}$ emission lines, and all three can be identified with bright X-ray
sources. The available ROSAT light curves of two of the objects show typical
flare-like variability. Thus, all three stars are active, very close potential
neighbours of the Sun, previously not mentioned as such, certainly deserving
further attention. In particular, these are very promising candidates for
trigonometric parallax programs.


title: The red optical afterglow of GRB 030725

abstract:
  We present a photometric study of the optical counterpart of the
long-duration Gamma Ray Burst (GRB) 030725, which triggered the HETE FREGATE
and WXM instruments on July 25th, 2003, and lasted more than 160s. An optical
counterpart was identified at the Bronberg Observatory in South Africa about 7
hours after the burst occurred. The optical afterglow (OA) was observed between
4 and 15 days after the burst with the 1.54m Danish telescope at La Silla in
the V, Rc, and Ic bands. We fit a broken power law to the data and determine a
break time in the light curve between 16 hours and 4.7 days after the first
detection of the burst. The decay slope is alpha1 = -0.59 +0.59/-0.44 before
and alpha2 = -1.43 +/- 0.06 after the break. A bump may be present in the light
curve, only significant at the 2-sigma level, 13.9 days after the main burst.
The spectral slope of the OA, measured 12 days after the burst, is -2.9 +/- 0.6
, i.e. it falls in the extreme red end of the distribution of previous OA
spectral slopes. Observations of the field 8 months after the burst with the
EMMI instrument on the NTT telescope (La Silla) resulted in an upper limit of
Rc=24.7 mag for the host galaxy of GRB 030725. The OA of GRB 030725 was
discovered at a private, non-professional observatory and we point out that
with the current suite of gamma ray satellites, an effort to organize future
contributions of amateur observers may provide substantial help in GRB light
curve follow up efforts.


title:
Evidence for a Weak Galactic Center Magnetic Field from Diffuse Low
  Frequency Nonthermal Radio Emission

abstract:
  New low-frequency 74 and 330 MHz observations of the Galactic center (GC)
region reveal the presence of a large-scale ($6\arcdeg\times 2\arcdeg$) diffuse
source of nonthermal synchrotron emission. A minimum energy analysis of this
emission yields a total energy of $\sim (\phi^{4/7}f^{3/7})\times 10^{52}$ ergs
and a magnetic field strength of $\sim 6(\phi/f)^{2/7}$ \muG (where $\phi$ is
the proton to electron energy ratio and $f$ is the filling factor of the
synchrotron emitting gas). The equipartition particle energy density is
$1.2(\phi/f)^{2/7}$ \evcm, a value consistent with cosmic-ray data. However,
the derived magnetic field is several orders of magnitude below the 1 mG field
commonly invoked for the GC. With this field the source can be maintained with
the SN rate inferred from the GC star formation. Furthermore, a strong magnetic
field implies an abnormally low GC cosmic-ray energy density. We conclude that
the mean magnetic field in the GC region must be weak, of order 10 \muG (at
least on size scales $\ga 125\arcsec$).


title: A climatic thermostat making Earth habitable

abstract:
  The mean surface temperature on Earth and other planets with atmospheres is
determined by the radiative balance between the non-reflected incoming solar
radiation and the outgoing long-wave black-body radiation from the atmosphere.
The surface temperature is higher than the black-body temperature due to the
greenhouse warming. Balancing the ice-albedo cooling and the greenhouse warming
gives rise to two stable climate states. A cold climate state with a
completelyice-covered planet, called Snowball Earth, and a warm state similar
to our present climate where greenhouse warming prevents the total glacition.
The warm state has dominated Earth in most of its geological history despite a
30 % fainter young Sun. The warming could have been controlled by a greenhouse
thermostat operating by temperature control of the weathering process depleting
the atmosphere from $CO_2$. This temperature control has permitted life to
evolve as early as the end of the heavy bombartment 4 billion years ago.


title: Multi-wavelength interferometry of evolved stars using VLTI and VLBA

abstract:
  We report on our project of coordinated VLTI/VLBA observations of the
atmospheres and circumstellar environments of evolved stars. We illustrate in
general the potential of interferometric measurements to study stellar
atmospheres and envelopes, and demonstrate in particular the advantages of a
coordinated multi-wavelength approach including near/mid-infrared as well as
radio interferometry. We have so far made use of VLTI observations of the near-
and mid-infrared stellar sizes and of concurrent VLBA observations of the SiO
maser emission. To date, this project includes studies of the Mira stars S Ori
and RR Aql as well as of the supergiant AH Sco. These sources all show strong
silicate emission features in their mid-infrared spectra. In addition, they
each have relatively strong SiO maser emission. The results from our first
epochs of S Ori measurements have recently been published and the main results
are reviewed here. The S Ori maser ring is found to lie at a mean distance of
about 2 stellar radii, a result that is virtually free of the usual uncertainty
inherent in comparing observations of variable stars widely separated in time
and stellar phase. We discuss the status of our more recent S Ori, RR Aql, and
AH Sco observations, and present an outlook on the continuation of our project.


title: The Lithium Content of the Galactic Halo Stars

abstract:
  Thanks to the accurate determination of the baryon density of the universe by
the recent cosmic microwave background experiments, updated predictions of the
standard model of Big Bang nucleosynthesis now yield the initial abundance of
the primordial light elements with an unprecedented precision. In the case of
$^7$Li, the CMB+SBBN value is significantly higher than the generally reported
abundances for Pop II stars along the so-called Spite plateau. In view of the
crucial importance of this disagreement which has cosmological, galactic and
stellar implications, we decided to tackle the most critical issues of the
problem by revisiting a large sample of literature Li data in halo stars that
we assembled following some strict selection criteria on the quality of the
original analyses. [Abridged]


title:
Discovery of a Galaxy Cluster in the Foreground of the Wide-Separation
  Quasar Pair UM425

abstract:
  We report the discovery of a cluster of galaxies in the field of UM425, a
pair of quasars separated by 6.5arcsec. Based on this finding, we revisit the
long-standing question of whether this quasar pair is a binary quasar or a
wide-separation lens. Previous work has shown that both quasars are at z=1.465
and show broad absorption lines. No evidence for a lensing galaxy has been
found between the quasars, but there were two hints of a foreground cluster:
diffuse X-ray emission observed with Chandra, and an excess of faint galaxies
observed with the Hubble Space Telescope. Here we show, via VLT spectroscopy,
that there is a spike in the redshift histogram of galaxies at z=0.77. We
estimate the chance of finding a random velocity structure of such significance
to be about 5%, and thereby interpret the diffuse X-ray emission as originating
from z=0.77, rather than the quasar redshift. The mass of the cluster, as
estimated from either the velocity dispersion of the z=0.77 galaxies or the
X-ray luminosity of the diffuse emission, would be consistent with the
theoretical mass required for gravitational lensing. The positional offset
between the X-ray centroid and the expected location of the mass centroid is
about 40kpc, which is not too different from offsets observed in lower redshift
clusters. However, UM425 would be an unusual gravitational lens, by virtue of
the absence of a bright primary lensing galaxy. Unless the mass-to-light ratio
of the galaxy is at least 80 times larger than usual, the lensing hypothesis
requires that the galaxy group or cluster plays a uniquely important role in
producing the observed deflections.
  Based on observations performed with the Very Large Telescope at the European
Southern Observatory, Paranal, Chile.


title:
The Evolution of the Dark Halo Spin Parameters lambda and lambda' in a
  LCDM Universe: The Role of Minor and Major Mergers

abstract:
  The evolution of the spin parameter of dark halos and the dependence on the
halo merging history in a set of dissipationless cosmological LCDM simulations
is investigated. Special focus is placed on the differences of the two commonly
used versions of the spin parameter, namely lambda=J*E^1/2/(G*M^5/2) (Peebles
80) and lambda'=J/(sqrt(2)*M_vir*R_vir*V_vir) (Bullock et al. 01). Though the
distribution of the spin transfer rate defined as the ratio of the spin
parameters after and prior to a merger is similar to a high degree for both,
lambda and lambda', we find considerable differences in the time evolution:
while lambda' is roughly independent of redshift, lambda turns out to increase
significantly with decreasing redshift. This distinct behaviour arises from
small differences in the spin transfer during accretion events. The evolution
of the spin parameter is strongly coupled with the virial ratio
eta:=2*E_kin/|E_pot| of dark halos. Major mergers disturb halos and increase
both their virial ratio and spin parameter for 1-2 Gyrs. At high redshifts
(z=2-3) many halos are disturbed with an average virial ratio of eta = 1.3
which approaches unity until z=0. We find that the redshift evolution of the
spin parameters is dominated by the huge number of minor mergers rather than
the rare major merger events.


title: The Luminosity Function of X-ray Point Sources in Centaurus A

abstract:
  We have studied the X-ray point source population of Centaurus A (NGC 5128)
using data from four archival CHANDRA observations. We detected 272 point-like
X-ray sources within a radius of 10 arcmin from the centre. Approximately half
of these are CXB sources, with the remaining half being LMXBs. The spatial
distribution of the LMXBs, both azimuthally averaged and 2-D, is consistent
with the distribution of the K-band light observed in the 2MASS survey. After
correction for the incompleteness effect we constrain the LMXB luminosity
function down to 2 times 10^{36} erg/s, much lower than previous studies of
LMXBs in elliptical galaxies. The obtained XLF flattens significantly below L_X
= 5 times 10^{37} erg/s and follows the dN/dL proportional to 1/L law in
agreement with the behaviour found earlier for LMXBs in the Milky Way and in
the bulge of M31.


title: VLTI observations of AGB stars

abstract:
  We report on recent observations of AGB stars obtained with the VLT
Interferometer (VLTI). We illustrate in general the potential of
interferometric measurements to study stellar atmospheres and circumstellar
envelopes, and demonstrate in particular the advantages of a coordinated
multi-wavelength approach including near/mid-infrared as well as radio
interferometry. We report on studies of the atmospheric structure of non-Mira
and Mira variable giants. We have used VLTI observations of the near- and
mid-infrared stellar sizes and concurrent VLBA observations of the SiO maser
emission. So far, this project includes studies of the Mira stars S Ori and RR
Aql as well as of the supergiant AH Sco. The results from our first epochs of S
Ori measurements have recently been published and the main results are reviewed
here. The S Ori maser ring is found to lie at a mean distance of approximately
2 stellar radii, a result that is virtually free of the usual uncertainty
inherent in comparing observations of variable stars widely separated in time
and stellar phase. We discuss the status of our more recent S Ori, RR Aql, and
AH Sco observations, and present an outlook on the continuation of our project.


title: On the Horizontal Branch of the Galactic Globular NGC2808

abstract:
  We present new UV (F218W) data for stars in the central region of the
Galactic globular cluster NGC2808, collected with the WFPC2 camera on board of
the Hubble Space Telescope. These data together with F439W and F555W-band data
and previous ground based observations provide a multifrequency coverage of the
cluster stellar population extending up to a distance of 1.7 times the cluster
core radius. We discuss this complete sample of stars, which includes 764 Red
Giant Branch (RGB) stars brighter than the Horizontal Branch (HB) luminosity
level, 1239 HB stars, 119 Asymptotic Giant Branch (AGB), and 22 AGB-manque'
stellar structures. As already known, we find that blue HB stars separate into
three distinct groups. However, our multiband photometry indicates that several
stars in the two hotter HB groups show a flat spectrum, thus suggesting the
binarity of these objects. Artificial star experiments suggest that at most 50%
of them might be photometric blends. Moreover, at variance with previous claims
one finds that canonical Zero Age Horizontal Branch (ZAHB) models do reach
effective temperatures typical of observed hot HB stars. We also show that the
ratio between HB and RGB stars brighter than the HB luminosity level steadly
increases when moving from the cluster center to the periphery, passing from
R=1.37 +/- 0.14 in the cluster core to R=1.95 +/- 0.26 in the outer cluster
regions. We discuss the possible origin of such a radial gradient in the
context of the Blue Tails phenomenon, advancing some suggestions concerning the
clumpy stellar distribution along the HB.


title: Parametrization of Quintessence and Its Potential

abstract:
  We develop a theoretical method of constructing the quintessence potential
directly from the effective equation of state function $w(z)$, which describes
the properties of the dark energy. We apply our method to four parametrizations
of equation of state parameter and discuss the general features of the
resulting potentials. In particular, it is shown that the constructed
quintessence potentials are all in the form of a runaway type.


title: Duality extended Chaplygin cosmologies with a big rip

abstract:
  We consider modifications to the Friedmann equation motivated by recent
proposals along these lines pursuing an explanation to the observed late time
acceleration. Here we show those modifications can be framed within a theory
with self-interacting gravity, where the term self-interaction refers here to
the presence of functions of $\rho$ and $p$ in the right hand side of the
Einstein equations. We then discuss the construction of the duals of the
cosmologies generated within that framework. After that we investigate the
modifications required to generate generalized and modified Chaplygin
cosmologies and show that their duals belong to a larger family of cosmologies
we call extended Chaplygin cosmologies. Finally, by letting the parameters of
those models take values not earlier considered in the literature we show some
representatives of that family of cosmologies display sudden future
singularities, which indicates their behavior is rather different from
generalized or modified Chaplygin gas cosmologies. This reinforces the idea
that modifications of gravity can be responsible for unexpected evolutionary
features in the universe.


title:
Discovery of Rapid X-ray Oscillations in the Tail of the SGR 1806-20
  Hyperflare

abstract:
  We have discovered rapid Quasi Periodic Oscillations (QPOs) in RXTE/PCA
measurements of the pulsating tail of the 27th December 2004 giant flare of SGR
1806-20. QPOs at about 92.5Hz are detected in a 50s interval starting 170s
after the onset of the giant flare. These QPOs appear to be associated with
increased emission by a relatively hard unpulsed component and are seen only
over phases of the 7.56s spin period pulsations away from the main peak. QPOs
at about 18 and 30Hz are also detected, 200-300s after the onset of the giant
flare. This is the first time that QPOs are unambiguously detected in the flux
of a Soft Gamma-ray Repeater, or any other magnetar candidate. We interpret the
highest QPOs in terms of the coupling of toroidal seismic modes with Alfven
waves propagating along magnetospheric field lines. The lowest frequency QPO
might instead provide indirect evidence on the strength of the internal
magnetic field of the neutron star.


title: Optical identification of IGR J19140+0951

abstract:
  IGR J19140+0951 was discovered by INTEGRAL in 2003 in the 4-100 keV band.
Observations with INTEGRAL and RXTE provide a tentative identification as a
high-mass X-ray binary (HMXB) with a neutron star as accretor. However, an
optical counterpart was thus far not established, nor was the presence of a
pulsar which is commonly observed in HMXBs. We observed IGR J19140+0951 with
Chandra and find the source to be active at a similar flux as previous
measurements. The lightcurve shows a marginally significant oscillation at 6.5
ks which requires confirmation. We determine a sub-arcsecond position from the
Chandra data and identify the heavily reddened optical counterpart 2MASS
19140422+0952577 in the 2MASS catalog. Optical follow-up observations with the
William Herschel Telescope at La Palma exhibit a continuum spectrum coming out
of extinction above 7000 Angstrom without strong absorption or emission
features. V, I and Ks band photometry point to an optical counterpart extincted
by A[V]=11+/-2. The extinction is consistent with the interstellar value. None
of the data reject the suspicion that IGR J19140+0951 is an HMXB with
additional circumstellar obscuration around the accretor.


title: Development of Kolmogorov spectrum in the pulsar radio emission

abstract:
  It is shown that the scattering of electromagnetic waves by Langmuir ones
taking into the account the electric drift motion of particles, is the most
intense nonlinear process and should be responsible for the formation of
radiation spectrum of radio pulsars. Performed analysis indicates that in the
case of existence of inertial interval formation of stationary spectra is
possible. Analysis of linear mechanisms of wave generation and silk allows to
conclude that only possible stationary solution has spectral index $\alpha
=-1.5$. Obtained spectrum is in good agreement with observational data.


title:
The imprints of local superclusters on the Sunyaev-Zel'dovich signals
  and their detectability with Planck

abstract:
  We use high-resolution hydrodynamical simulations of large-scale structure
formation to study the imprints of the local superclusters onto the full-sky
Sunyaev-Zel'dovich (SZ) signals. Following (Mathis et al. 2002), the initial
conditions have been statistically constrained to reproduce the density field
within a sphere of 110 Mpc around the Milky Way, as observed in the IRAS 1.2-Jy
all-sky redshift survey. As a result, the positions and masses of prominent
galaxy clusters and superclusters in our simulations coincide closely with
their real counterparts in the local universe. We present the results of two
different runs, one with adiabatic gas physics only, and one also including
cooling, star formation and feedback. By analysing the full-sky maps for the
thermal and kinetic SZ signals extracted from these simulations, we find that
for multipoles with l<100 the power spectrum is dominated by the prominent
local superclusters, and its amplitude at these scales is a factor of two
higher than that obtained from unconstrained simulations; at lower multipoles
(l<20) this factor can even reach one order of magnitude. We check the
influence of the SZ effect from local superclusters on the cosmic microwave
background (CMB) power spectrum at small multipoles and find it negligible and
with no signs of quadrupole-octopole alignment. However, performing simulations
of the CMB radiation including the experimental noise at the frequencies which
will be observed by the Planck satellite, we find results suggesting that an
estimate of the SZ power spectrum at large scales can be extracted.


title:
On the effect of cyclotron emission on the spectral distortions of the
  cosmic microwave background

abstract:
  We have investigated the role of the cyclotron emission associated to cosmic
magnetic fields on the evolution of CMB spectral distortions by considering the
contributions by spontaneous and stimulated emission and by absorption in the
computation of the photon and energy injection rates. These cyclotron emission
rates have been numerically compared with those of the relevant radiative
processes operating in the cosmic plasma, bremsstrahlung and double Compton
scattering, for realistic CMB distorted spectra at early and late epochs. For
reasonable magnetic field strengths we find that the cyclotron emission
contribution is much smaller than the bremsstrahlung and double Compton
contributions, because of their different frequency locations and the high
bremsstrahlung and double Compton efficiency to keep the long wavelength region
of the CMB spectrum close to a blackbody (at electron temperature) during the
formation of the spectral distortion. Differently from previous analyses, we
find that for a very large set of dissipation mechanisms the role of cyclotron
emission in the evolution of CMB spectral distortions is negligible and, in
particular, it cannot re-establish a blackbody spectrum after the generation of
a realistic early distortion. The constraints on the energy exchanges at
various cosmic times can be then derived, under quite general assumptions, by
considering only Compton scattering, bremsstrahlung, and double Compton, other
than, obviously, the considered dissipation process. Finally, upper limits to
the CMB polarization degree induced by cyclotron emission have been estimated.


title:
M74 X-1 (CXOU J013651.1+154547): An Extremely Variable Ultraluminous
  X-Ray Source

abstract:
  Ultraluminous X-ray sources (ULXs) have been described variously as the most
luminous normal X-ray binaries, as hypernovae, and as "intermediate-mass" black
holes with masses of hundreds to thousands of solar masses. We present results
on M74 X-1 (CXOU J013651.1+154547), a ULX in the nearby spiral galaxy M74 (NGC
628), from observations by Chandra and XMM-Newton. M74 X-1is a persistent
source which exhibits extreme variability and changes in spectral state on
timescales of several thousand seconds. Its variability timescales and behavior
resemble some Galactic microquasars. This suggests that the emission mechanism
may be related to relativistically beamed jets, and that M74 X-1 could be an
extragalactic "microblazar" -- a microquasar whose jet axis is aligned with our
line of sight. We also note that its spectrum is consistent with the presence
of a low-temperature disk blackbody component, which, assuming it is due to
radiation from an accretion disk, could indicate that M74 X-1 contains an
intermediate-mass black hole.


title: XMM-Newton and VLT observations of the afterglow of GRB040827

abstract:
  The field of the Gamma-Ray Burst GRB 040827 was observed with XMM-Newton and
with the ESO/VLT starting ~6 and ~12 hours after the burst, respectively. A
fading X-ray afterglow is clearly detected with the XMM-Newton/EPIC instrument,
with a time decay t^(-delta), with delta=1.41+/-0.10. Its spectrum is well
described by a power law (photon index Gamma=2.3+/-0.1) affected by an
absorption largely exceeding (by a factor ~5) the expected Galactic one,
requiring the contribution of an intrinsic, redshifted absorber. In the
optical/NIR range, the afterglow emission was observed in the Ks band, as a
weak source superimposed to the host galaxy, with magnitude Ks=19.44+/-0.13 (12
hours after the GRB, contribution from the host subtracted); in other bands the
flux is dominated by the host galaxy. Coupling constraints derived from X-ray
spectral fitting and from photometry of the host, we estimated a gas column
density in the range (0.4-2.6)x10^22 cm^-2 in the GRB host galaxy, likely
located at a redshift 0.5<z<1.7. GRB 040827 stands out as the best example of
an X-ray afterglow with intrinsic absorption.


title:
Magnetic deflections and possible sources of the ultra-high-energy
  cosmic rays in the AGASA-HiRes-Yakutsk cluster

abstract:
  The cluster of ultra-high-energy cosmic rays observed by the AGASA, HiRes and
Yakutsk experiments is studied with respect to possible deflections of
particles in regular magnetic fields. Best-fit positions of a potential source
of these clustered particles are found, with account of the errors in energy
estimation, both in the frameworks of particular models of the Galactic
magnetic field and treating the direction and the amount of deflection as free
parameters. The study suggests that an unknown regular component of either
Galactic or extragalactic magnetic field may dominate over modelled components
in the direction of the cluster. Possible sources of the cosmic rays in that
direction are considered.


title: C and N Abundances in Stars At the Base of the Red Giant Branch in M15

abstract:
  We present an analysis of a large sample of moderate resolution Keck LRIS
spectra of subgiants and stars at the base of the RGB in M15, most within the
range 16.5 < V < 19.5 (1.2 < M_V < 4.2), with the goal of deriving C abundances
(from the G band of CH) and N abundances (from the NH band at 3360 A).
Star-to-star stochastic variations with significant range in both [C/Fe] and
[N/Fe] are found at all luminosities extending to the subgiants at M_V ~ +3.
The C and N abundances appear anti-correlated, as would be expected from the
CN-cycle processing of stellar material. Yet these M15 stars are considerably
fainter than the RGB bump, the point at which deep mixing is believed to set
in. On this basis, while the observed abundance pattern is consistent with
proton capture nucleosynthesis, we infer that the site of the reactions is
likely not within the present sample. The range of variation of the N
abundances is very large and the sum of C+N increases as C decreases. To
reproduce this requires the incorporation not only of CN but also of
ON-processed material. Combining our work with that of Trefzger et al (1983)
for the brighter giants in M15, we find strong evidence for additional
depletion of C among the most luminous giants. This presumably represents the
first dredge up (with enhanced deep mixing) expected for such luminous cluster
RGB stars in the course of normal stellar evolution as they cross the RGB bump.
We compare the behavior of these patterns for C and N in globular clusters
covering a wide range of metallicity and of current mass and discuss possible
scenarios to reproduce the observed behavior of these key elements. (abridged)


title: Double nucleus in M83

abstract:
  M 83 is one of the nearest galaxies with an enhanced nuclear star formation
and it presents one of the best opportunities to study the kinematics and
physical properties of a circumnuclear starburst. Our three-dimensional
spectroscopy data in R band confirm the presence of a secondary nucleus or mass
concentration (previously suggested by Thatte and coworkers). We determine the
position of this hidden nucleus, which would be more massive than the visible
one, and was not detected in the optical HST images due, probably, to the
strong dust extinction. The optical nucleus has a mass of 5 x 10^6 M_Sun / sin
i (r < 1''.5), and the hidden nucleus, located 3''.9 +/- 0''.5 at the NW (PA
271 +/- 15 deg) of the optical nucleus, would have a mass of 1 x 10^7 M_Sun /
sin i (r < 1''.5). The emission line ratio map also unveils the presence of a
second circumnuclear ring structure, previously discovered by IR imaging
(Elmegreen and coworkers). The data allow us to resolve the behavior of the
interstellar medium inside the circumnuclear ring and around the binary mass
concentration.


title: The fundamental plane of isolated early-type galaxies

abstract:
  Here we present new measurements of effective radii, surface brightnesses and
internal velocity dispersions for 23 isolated early-type galaxies. The
photometric properties are derived from new multi-colour imaging of 10
galaxies, whereas the central kinematics for 7 galaxies are taken from
forthcoming work by Hau & Forbes. These are supplemented with data from the
literature. We reproduce the colour-magnitude and Kormendy relations and
strengthen the result of Paper I that isolated galaxies follow the same
photometric relations as galaxies in high density environments. We also find
that some isolated galaxies reveal fine structure indicative of a recent merger
while others appear undisturbed. We examine the Fundamental Plane in both
traditional R_e, mu_e and sigma space and also kappa-space. Most isolated
galaxies follow the same Fundamental Plane tilt and scatter for galaxies in
high density environments. However, a few galaxies notably deviate from the
plane in the sense of having smaller M/L ratios. This can be understood in
terms of their younger stellar populations, which are presumably induced by a
gaseous merger. Overall, isolated galaxies have similar properties to those in
roups and clusters with a slight enhancement in the frequency of recent
mergers/interactions.


title: Alternatives to Dark Matter and Dark Energy

abstract:
  We review the underpinnings of the standard Newton-Einstein theory of
gravity, and identify where it could possibly go wrong. In particular, we
discuss the logical independence from each other of the general covariance
principle, the equivalence principle and the Einstein equations, and discuss
how to constrain the matter energy-momentum tensor which serves as the source
of gravity. We identify the a priori assumption of the validity of standard
gravity on all distance scales as the root cause of the dark matter and dark
energy problems, and discuss how the freedom currently present in gravitational
theory can enable us to construct candidate alternatives to the standard theory
in which the dark matter and dark energy problems could then be resolved. We
identify three generic aspects of these alternate approaches: that it is a
universal acceleration scale which determines when a luminous Newtonian
expectation is to fail to fit data, that there is a global cosmological effect
on local galactic motions which can replace galactic dark matter, and that to
solve the cosmological constant problem it is not necessary to quench the
cosmological constant itself, but only the amount by which it gravitates.


title:
Lorentz violation at high energy: concepts, phenomena and astrophysical
  constraints

abstract:
  We consider here the possibility of quantum gravity induced violation of
Lorentz symmetry (LV). Even if suppressed by the inverse Planck mass such LV
can be tested by current experiments and astrophysical observations. We review
the effective field theory approach to describing LV, the issue of naturalness,
and many phenomena characteristic of LV. We discuss some of the current
observational bounds on LV, focusing mostly on those from high energy
astrophysics in the QED sector at order E/M_Planck. In this context we present
a number of new results which include the explicit computation of rates of the
most relevant LV processes, the derivation of a new photon decay constraint,
and modification of previous constraints taking proper account of the helicity
dependence of the LV parameters implied by effective field theory.


title: Numerical self-consistent stellar models of thin disks

abstract:
  We find a numerical self-consistent stellar model by finding the distribution
function of a thin disk that satisfies simultaneously the Fokker-Planck and
Poisson equations. The solution of the Fokker-Planck equation is found by a
direct numerical solver using finite differences and a variation of Stone's
method. The collision term in the Fokker-Planck equation is found using the
local approximation and the Rosenbluth potentials. The resulting diffusion
coefficients are explicitly evaluated using a Maxwellian distribution for the
field stars. As a paradigmatic example, we apply the numerical formalism to
find the distribution function of a Kuzmin-Toomre thin disk. This example is
studied in some detail showing that the method applies to a large family of
actual galaxies.


title: Absolute Spectrophotometry of Northern Compact Planetary Nebulae

abstract:
  We present medium-dispersion spectra and narrowband images of six northern
compact planetary nebulae (PNe): BoBn 1, DdDm 1, IC 5117, M 1-5, M 1-71, and
NGC 6833. From broad-slit spectra, total absolute fluxes and equivalent widths
were measured for all observable emission lines. High signal-to noise emission
line fluxes of H-alpha, H-beta, [OIII], [NII], and HeI may serve as emission
line flux standards for northern hemisphere observers. From narrow-slit
spectra, we derive systemic radial velocities. For four PNe, available emission
line fluxes were measured with sufficient signal-to-noise to probe the physical
properties of their electron densities, temperatures, and chemical abundances.
BoBn 1 and DdDm 1, both type IV PNe, have an H-beta flux over three sigma away
from previous measurements. We report the first abundance measurements of M
1-71. NGC 6833 measured radial velocity and galactic coordinates suggest that
it is associated with the outer arm or possibly the galactic halo, and its low
abundance ([O/H]=1.3x10E-4) may be indicative of low metallicity within that
region.


title: Identifying Near Earth Object Families

abstract:
  The study of asteroid families has provided tremendous insight into the
forces that sculpted the main belt and continue to drive the collisional and
dynamical evolution of asteroids. The identification of asteroid families
within the NEO population could provide a similar boon to studies of their
formation and interiors. In this study we examine the purported identification
of NEO families by Drummond (2000) and conclude that it is unlikely that they
are anything more than random fluctuations in the distribution of NEO
osculating orbital elements. We arrive at this conclusion after examining the
expected formation rate of NEO families, the identification of NEO groups in
synthetic populations that contain no genetically related NEOs, the orbital
evolution of the largest association identified by Drummond (2000), and the
decoherence of synthetic NEO families intended to reproduce the observed
members of the same association. These studies allowed us to identify a new
criterion that can be used to select real NEO families for further study in
future analyses, based on the ratio of the number of pairs and the size of
strings to the number of objects in an identified association.


title:
X-Ray Observations of the Black Hole Transient 4U 1630-47 During Two
  Years of X-Ray Activity

abstract:
  The black hole candidate (BHC) X-ray transient 4U 1630-47 continuously
produced strong X-ray emission for over 2 years during 2002-2004. We use
observations made with the Rossi X-ray Timing Explorer (RXTE) to study the
source throughout the outburst along with hard X-ray images from the
INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL). The source exhibits
extreme behaviors, including measured inner disk temperatures (Tin) between 2.7
and 3.8 keV, which are only rivaled by the brightest BHC systems. If the high
temperatures are caused by the dominance of electron scattering opacity in the
inner regions of the accretion disk, a luminosity >20% of the Eddington limit
is theoretically required. We detect several types of variability, including
hard 10-100 s flares at the highest disk luminosities in a regime where the
source deviates from the Ldisk/Tin relationship that is seen at lower
luminosities, possibly suggesting that we are seeing transitions between a
standard disk and a "slim" disk. The X-ray properties in 2002-2004 are
significantly different from those seen during the 1998 outburst, which is the
only outburst with detected radio jet emission. Our results support the
"jet-line" concept recently advanced by Fender and co-workers. Our study allows
for a test of the quantitative McClintock & Remillard spectral state
definitions. We also report on detections of the nearby sources IGR J16320-4751
and IGR J16358-4726.


title: The Distribution of Satellite Galaxies in a Lambda-CDM Universe

abstract:
  We compute the locations of satellite galaxies with respect to their hosts
using the Lambda-CDM GIF simulation. If the major axes of the hosts' images are
perfectly aligned with the major axes of their projected mass, the satellites
are located preferentially close to the hosts' major axes. In this case, the
degree of anisotropy in the satellite locations is a good tracer of the
flattening of the hosts' halos. If all hosts have luminous circular disks, the
symmetry axes of the projected mass and light are not perfectly aligned, and
the locations of the satellites depend upon how the hosts' disks are placed
within their halos. If the disk angular momentum vectors are aligned with the
major axes of the halos, the satellites show a pronounced "Holmberg effect". If
the disk angular momentum vectors are aligned with the intermediate axes of the
local large scale structure, the distribution of satellite locations is
essentially isotropic. If the disk angular momentum vectors are aligned with
either the minor axes or with the net angular momentum vectors of the halos,
the satellites are distributed anisotropically about their hosts, with a
preference for being found nearby the hosts' major axes. This agrees well with
the observation that satellite galaxies in the Sloan Digital Sky Survey tend to
be found nearby the major axes of their hosts, and suggests that the mass and
light of SDSS host galaxies must be fairly well aligned in projection on the
sky.


title:
Observations in the 1.3 and 1.5 THz Atmospheric Windows with the
  Receiver Lab Telescope

abstract:
  The Receiver Lab Telescope (RLT) is a ground-based terahertz telescope; it is
currently the only instrument producing astronomical data between 1 and 2 THz.
The capabilities of the RLT have been expanding since observations began in
late 2002. Initial observations were limited to the 850 GHz and 1.03 THz
windows due to the availability of solid state local oscillators. In the last
year we have begun observations with new local oscillators for the 1.3 and 1.5
THz atmospheric windows. These oscillators provide access to the 11-10 and
13-12 lines of CO at 1.267 and 1.497 THz, as well as the [N II] line at 1.461
THz. We report on our first measurements of these high CO transitions, which
represent the highest-frequency detections ever made from the ground. We also
present initial observations of [N II] and discuss the implications of this
non-detection for the standard estimates of the strength of this line.


title:
Hydrodynamic Simulations of A Moving Substructure in A Cluster of
  Galaxies: Cold Fronts and Turbulence Generation

abstract:
  We perform three dimensional hydrodynamical simulations of a moving
substructure in a cluster of galaxies. We investigate dynamical evolution of
the intracluster medium (ICM) in and around the substructure moving radially in
the larger cluster's gravitational potential, and its observational
consequences. After the substructure passes the larger cluster's center, a bow
shock and clear contact discontinuity form in front of it. The contact
discontinuity looks like a sharp cold front in the X-ray image synthesized from
the simulation results. This agrees with a structure found in 1E 0657-56. The
flow structure remains laminar before the first turnaround because the
ram-pressure stripping is dominant over the development of Kelvin-Helmholtz
instabilities on the boundary between the substructure and the ambient ICM.
  When a subcluster oscillates radially around the larger cluster's center,
both Kelvin-Helmholtz and Rayleigh-Taylor instabilities develop well and the
flow structure becomes highly turbulent. Around the turnaround, the
subcluster's cold gas is pushed out of its potential well.
  Therefore, the cold gas component appears to be in front of the subcluster. A
relatively blunt cold front appears in the simulated
  X-ray image because the contact discontinuity is perturbed by Rayleigh-Taylor
instabilities. This can explain the ICM structure found in A168.


title: Be/X-ray binaries and candidates: catalogue

abstract:
  We present a compilative catalogue of Be/X-ray binaries and candidates in the
Galaxy and in the Large and Small Magellanic Clouds. This catalogue contains
130 sources and provides information on names and spectral types of optical
components, distances, spin characteristics of neutron stars, and on orbital
and X-ray properties of binary systems.
  We give brief comments on each object and provide necessary references to
original data.


title:
Spectral lags and the energy dependence of pulse width in gamma-ray
  bursts: contributions from the relativistic curvature effect

abstract:
  We compute the temporal profiles of the gamma-ray burst pulse in the four
Burst and Transient Source Experiment (BATSE) Large Area Detector (LAD)
discriminator energy channels, with the relativistic curvature effect of a
expanding fireball being explicitly investigated. Assuming an intrinsic 'Band'
shape spectrum and an intrinsic energy-independent emission profile, we show
that merely the curvature effect can produce detectable spectral lags if the
intrinsic pulse profile has a gradually decaying phase. We examine the spectral
lag's dependences on some physical parameters, such as the Lorentz factor
\Gamma, the low-energy spectral index, \alpha, of the intrinsic spectrum, the
duration of the intrinsic radiation t_d' and the fireball radius R. It is shown
that approximately the lag \propto \Gamma ^{-1} and \propto t_d', and a
spectrum with a more extruded shape (a larger \alpha) causes a larger lag. We
find no dependence of the lag on R. Quantitatively, the lags produced from the
curvature effect are marginally close to the observed ones, while larger lags
require extreme physical parameter values, e.g., \Gamma < 50, or \alpha > -0.5.
The curvature effect causes an energy-dependent pulse width distribution but
the energy dependence of the pulse width we obtained is much weaker than the
observed W \propto E^{-0.4} one. This indicates that some intrinsic
mechanism(s), other than the curvature effect, dominates the pulse narrowing of
GRBs.


title: Gravity-wave detectors as probes of extra dimensions

abstract:
  If string theory is correct, then our observable Universe may be a
3-dimensional "brane" embedded in a higher-dimensional spacetime. This
theoretical scenario should be tested via the state-of-the-art in gravitational
experiments -- the current and upcoming gravity-wave detectors. Indeed, the
existence of extra dimensions leads to oscillations that leave a spectroscopic
signature in the gravity-wave signal from black holes. The detectors that have
been designed to confirm Einstein's prediction of gravity waves, can in
principle also provide tests and constraints on string theory.


title: Recent Results from the AMANDA-II neutrino telescope

abstract:
  AMANDA-II is an operating neutrino telescope located at the South Pole.
Recent results of AMANDA are presented, including the examination of the
diffuse neutrino flux, permanent and transient point source analyses, and
indirect dark matter searches. A brief outlook on the IceCube neutrino
telescope currently under construction at the South Pole is given.


title:
Diffusive convective overshoot in core He-burning intermediate mass
  stars. I: the LMC metallicity

abstract:
  We present detailed evolutionary calculations focused on the evolution of
intermediate mass stars with 3 Msun < M < 9 Msun of metallicity typical of the
Large Magellanic Cloud (LMC), i.e. Z=0.008. We compare carefully the models
calculated by adopting a diffusive scheme for chemical mixing, in which nuclear
burning and mixing are self-consistently coupled, while the eddy velocities
beyond the formal convective core boundary are treated to decay exponentially,
and those calculated with the traditional instantaneous mixing approximation.
We find that: i) the physical and chemical behaviour of the models during the
H-burning phase is independent of the scheme used for the treatment of mixing
inside the CNO burning core; ii) the duration of the He-burning phase relative
to the MS phase is systematically longer in the diffusive models, due to a
slower redistribution of helium to the core from the outer layers; iii) the
fraction of time spent in the blue part of the clump, compared to the stay in
the red, is larger in the diffusive models. The differences described in points
ii) and iii) tend to vanish for M > Msun. In terms of the theoretical
interpretation of an open cluster stellar population, the differences
introduced by the use of a self-consistent scheme for mixing in the core with
adjacent exponential decay are relevant for ages in the range 80 Myr < t < 200
Myr. These results are robust, since they are insensitive to the choice of the
free-parameters regulating the extension of the extra-mixing region.


title: Radio-loud flares from microquasars and radio-loudness of quasars

abstract:
  The low-frequency power spectra of the X-ray and radio emission from four
microquasars suggest that two distinct modes of energy output are at work: (i)
the `coupled' mode in which the X-ray and radio luminosities are closely
coupled and vary only weakly, and (ii) the `flaring' mode, which dramatically
boosts the radio luminosity but makes no impact on the X-ray luminosity. The
systems are in the flaring mode only a few percent of the time. However, flares
completely dominate the power spectrum of radio emission, with the consequence
that sources in which the flaring mode occurs, such as GRS 1915+105 and Cyg
X-3, have radio power spectra that lie more than an order of magnitude above
the corresponding X-ray power spectra. Of the four microquasars for which we
have examined data, in only one, Cyg X-1, is the flaring mode seemingly
inactive. While Cyg X-1 is a black-hole candidate, one of the three flaring
sources, Sco X-1, is a neutron star. Consequently, it is likely that both modes
are driven by the accretion disk rather than black-hole spin. Radio imaging
strongly suggests that the flaring mode involves relativistic jets. A typical
microquasar is in the flaring mode a few percent of the time, which is similar
to the fraction of quasars that are radio loud. Thus there may be no essential
difference between radio-loud and radio-quiet quasars; radio loudness may
simply be a function of the epoch at which the source is observed.


title: Search for Planetary Candidates within the OGLE Stars

abstract:
  We propose a method to distinguish between planetary and stellar companions
to stars which present a periodic decrease in brightness, interpreted as a
transit. Light curves from a total of 177 stars from the OGLE project were
fitted by the model which simulates planetary transits using an opaque disk in
front of an image of the Sun. The simulation results yield the orbital radius
in units of stellar radii, the orbital inclination angle, and the ratio of the
planet to the star radii. Combining Kepler's third law with a mass-radius
relation for main sequence stars, it was possible to estimate values for the
masses and radii of both the primary and secondary objects. This model was
successfully tested with the confirmed planets orbiting the stars HD 209458,
TrES-1, OGLE-TR-10, 56, 111, 113, and 132. The method consists of selecting as
planetary candidates only those objects with primary densities between 0.7 and
2.3 solar densities (F, G, and K stars) and secondaries with radius less than
1.5 Jupiter radius. The method is not able to distinguish between a planet and
a dwarf star with mass less than 0.1 $M_\odot$, such as OGLE-TR-122. We propose
a selection of 28 planetary candidates (OGLE-TR-49, 51, 55, 63, 71, 76, 90, 97,
100, 109, 114, 127, 130, 131, 134, 138, 140, 146, 151, 155, 159, 164, 165, 169,
170, 171, 172, and 174) for high resolution spectroscopy follow up.


title: The Gas Content in Galactic Disks: Correlation with Kinematics

abstract:
  We consider the relationship between the total HI mass in late-type galaxies
and the kinematic properties of their disks. The mass $M_HI$ for galaxies with
a wide variety of properties, from dwarf dIrr galaxies with active star
formation to giant low-brightness galaxies, is shown to correlate with the
product $V_c R_0$ ($V_c$ is the rotational velocity, and $R_0$ is the radial
photometric disks scale length), which characterizes the specific angular
momentum of the disk. This relationship, along with the anticorrelation between
the relative mass of HI in a galaxy and $V_c$, can be explained in terms of the
previously made assumption that the gas density in the disks of most galaxies
is maintained at a level close to the threshold (marginal) stability of a
gaseous layer to local gravitational perturbations. In this case, the
regulation mechanism of the star formation rate associated with the growth of
local gravitational instability in the gaseous layer must play a crucial role
in the evolution of the gas content in the galactic disk.


title:
On the Observational Status of Ultrahigh Energy Cosmic Rays and their
  Possible Origin in Starburst-Like Galaxies

abstract:
  This paper presents a brief review of the current status of ultrahigh energy
cosmic ray observations and discusses nearby starburst-like galaxies as their
possible origin.


title: The cosmic shear three-point functions

abstract:
  We investigate the three-point functions of the weak lensing cosmic shear,
using both analytic methods and numerical results from N-body simulations. The
analytic model, an isolated dark matter halo with a powerlaw profile chosen to
fit the effective index at the scale probed, can be used to understand the
basic properties of the eight three-point functions observed in simulations. We
use this model to construct a single three-point function estimator that
"optimally" combines the eight three-point functions. This new estimator is an
alternative to Map statistics and provides up to a factor of two improvement in
signal to noise compared to previously used combinations of cosmic shear
three-point functions.


title:
Millimeter Wave Observations of the Core-Jet and Molecular Gas in the FR
  I Radio Galaxy NGC 3801

abstract:
  We present BIMA 3 mm observations of the radio continuum source and the
molecular gas disk in the radio loud Fanaroff & Riley Type I (FR I)galaxy
NGC3801.We have detected a continuum source in the nucleus and determined that
it has a flat millimeter-wave spectrum, suggesting that the emission is
non-thermal and due to an AGN; the radio core is not evident in existing VLA
observations. We also map the extended 3 mm emission from the previously known
radio jets. In addition, we detect CO (1--0) emission associated with the dust
disk observed in previous HST images. A velocity gradient is observed,
indicating a two kpc radius rotating gas ring or disk oriented roughly
perpendicular to the radio jets. The inferred molecular gas mass of the disk is
$M(H_{2})=3\times10^{8}M_{\odot}$, about 1% of the dynamical mass. We also find
a $\sim 10^8$ M$_\odot$ molecular gas clump not associated with the gas disk.
There is evidence that this gas is associated with a merger and is infalling.
This suggests that FR I type activity is related to merger activity, as is
thought to be the case for FR II type radio galaxies. We also find indications
that one of the radio jets is entraining gas from the infalling molecular gas.


title:
Direct Measurements of Black Hole Charge with Future Astrometrical
  Missions

abstract:
  Recently, Zakharov et al. (2005) considered the possibility of evaluating the
spin parameter and the inclination angle for Kerr black holes in nearby
galactic centers by using future advanced astrometrical instruments. A similar
approach which uses the characteristic properties of gravitational
retro-lensing images can be followed to measure the charge of
Reissner-Nordstrom black hole. Indeed, in spite of the fact that their
formation might be problematic, charged black holes are objects of intensive
investigations. From the theoretical point of view it is well-known that a
black hole is described by only three parameters, namely, its mass M, angular
momentum J and charge Q. Therefore, it would be important to have a method for
measuring all these parameters, preferably by model independent way. In this
paper, we propose a procedure to measure the black hole charge by using the
size of the retro-lensing images that can be revealed by future astrometrical
missions. A discussion of the Kerr-Newmann black hole case is also offered.


title: Gamma-ray and neutrino emission from misaligned microquasars

abstract:
  Microquasars are accreting X-ray binary systems with non-thermal radio jets.
In some of these systems the jet is expected to be strongly misaligned with the
perpendicular to the orbital plane. If the donor star is an early-type star,
the jet could collide with the stellar wind producing a standing shock between
the compact object and the stellar surface. Relativistic particles injected by
the jet can be re-accelerated and isotropized at the colliding region. If the
jet has hadronic content, TeV protons will diffuse into the inner, dense wind
leading to gamma-ray and neutrino production from interactions with the matter
of the wind. In the case of very powerful jets, the wind pressure can be
overbalanced and the jet might impact directly onto the stellar surface. We
present estimates of the gamma-ray and neutrino luminosities for different sets
of parameters in these scenarios and we briefly discuss the effects of this
radiation on the donor star and its detectability with current instruments.


title: Mass Loss Due to Sputtering and Thermal Processes in Meteoroid Ablation

abstract:
  Conventional meteoroid theory assumes that the dominant mode of ablation is
by evaporation following intense heating during atmospheric flight. In this
paper we consider the question of whether sputtering may provide an alternative
disintegration process of some importance.For meteoroids in the mass range from
10^-3 to 10^-13 kg and covering a meteor velocity range from 11 to 71 km/s, we
numerically modeled both thermal ablation and sputtering ablation during
atmospheric flight. We considered three meteoroid models believed to be
representative of asteroidal (3300 kg m^-3 mass density), cometary (1000 kg
m^-3) and porous cometary (300 kg m^-3) meteoroid structures. Atmospheric
profiles which considered the molecular compositions at different heights were
used in the sputtering calculations. We find that while in many cases
(particularly at low velocities and for relatively large meteoroid masses)
sputtering contributes only a small amount of mass loss during atmospheric
flight, in some cases sputtering is very important. For example, a 10^-10 kg
porous meteoroid at 40 km/s will lose nearly 51% of its mass by sputtering,
while a 10^-13 kg asteroidal meteoroid at 60 km/s will lose nearly 83% of its
mass by sputtering. We argue that sputtering may explain the light production
observed at very great heights in some Leonid meteors. The impact of this work
will be most dramatic for very small meteoroids such as those observed with
large aperture radars.