title:
Determination of the mass loss rate and the terminal velocity of stellar
  winds. I Genetic algorithm for automatic line profile fitting

abstract:
  Terminal wind velocity and mass loss rate are the most fundamental parameters
of stellar winds. Unfortunately, their determination calls for high resolution
spectroscopy in a range of wavelengths spanning from the ultraviolet to the
infrared. For weak and/or distant objects, this becomes unfeasible.
Nevertheless, it is possible to obtain an accurate estimate of these parameters
through a simplified study of the formation processes of resonant lines which
show P Cyg profiles. In this case, the line profile is a complex function of 6
parameters, with the radiative transport treatment becoming relatively
inexpensive. However, preforming a 6 dimensional parameter fit raises a number
of problems if one seeks an objective and automatic procedure to yield the
optimal values, from which wind velocities and mass loss rates can be
estimated.
  Useing a Likelihood function to construct a well defined statistical
estimator of the goodness of fit which corresponds to a given model, we turn to
a genetic algorithm through which we find the global maximum of the 6
dimensional Likelihood hyper-surface. We here present the implementation of the
method, its successful testing with synthetic line profiles, where the answer
is known in advance, together with first results of its application to real
data


title:
Equatorial scattering and the structure of the broad-line region in
  Seyfert nuclei: evidence for a rotating disc

abstract:
  We present detailed scattering models confirming that distinctive variations
in polarization across the broad Halpha line, which are observed in a
significant fraction of Seyfert 1 galaxies, can be understood in terms of a
rotating line-emitting disc surrounded by a co-planar scattering region (the
equatorial scattering region). The predicted polarization properties are:
averaged over wavelength, the position angle of polarization is aligned with
the projected disc rotation axis and hence also with the radio source axis;
(ii) the polarization PA rotates across the line profile, reaching equal but
opposite (relative to the continuum PA) rotations in the blue and red wings;
(iii) the degree of polarization peaks in the line wings and passes through a
minimum in the line core. We identify 11 objects which exhibit these features
to different degrees. In order to reproduce the large amplitude PA rotations
observed in some cases, the scattering region must closely surround the
emission disc and the latter must itself be a relatively narrow annulus --
presumably the Halpha-emitting zone of a larger accretion disc. Asymmetries in
the polarization spectra may be attributable to several possible causes,
including bulk radial infall in the equatorial scattering region, or
contamination by polar scattered light. The broad Halpha lines do not, in
general, exhibit double-peaked profiles, suggesting that a second
Halpha-emitting component of the broad-line region is present, in addition to
the disc.


title: Dust diffusion in protoplanetary discs by magnetorotational turbulence

abstract:
  We measure the turbulent diffusion coefficient of dust grains embedded in
magnetorotational turbulence in a protoplanetary disc directly from numerical
simulations and compare it to the turbulent viscosity of the flow. The
simulations are done in a local coordinate frame comoving with the gas in
Keplerian rotation. Periodic boundary conditions are used in all directions,
and vertical gravity is not applied to the gas. Using a two-fluid approach,
small dust grains of various sizes (with friction times up to $\varOmega_0
\tau_{\rm f}=0.02$) are allowed to move under the influence of friction with
the turbulent gas. We measure the turbulent diffusion coefficient of the dust
grains by applying an external sinusoidal force field acting in the vertical
direction on the dust component only. This concentrates the dust around the
mid-plane of the disc, and an equilibrium distribution of the dust density is
achieved when the vertical settling is counteracted by the turbulent diffusion
away from the mid-plane. Comparing with analytical expressions for the
equilibrium concentration we deduce the vertical turbulent diffusion
coefficient. The vertical diffusion coefficient is found to be lower than the
turbulent viscosity and to have an associated vertical diffusion Prandtl number
of about 1.5. A similar radial force field also allows us to measure the radial
turbulent diffusion coefficient. We find a radial diffusion Prandtl number of
about 0.85 and also find that the radial turbulent diffusion coefficient is
around 70% higher than the vertical. We also find evidence for trapping of dust
grains of intermediate friction time in turbulent eddies.


title:
Long-term stability of collisionless equilibrium configurations;
  algorithms

abstract:
  We present the summary of the theoretical aspects and algorithms used in an
undergraduate (JRG) summer project based on numerical N-body simulations of
collisionless systems. First, we review the importance of numerical N-body
simulations in astrophysics. We introduce the different codes used and their
performances. We then introduce four famous density profiles : Hernquist, NFW,
truncated isothermal sphere, and Plummer. The history of these profiles and
their dynamical properties are discussed in the third section. In the fourth
section, we present the Barnes & Hut tree code, its features and performances.
We then explain how to build and incorporate a multiple time stepping scheme in
a tree code. The fifth section is dedicated to the different physical
measurements we used to characterize the dynamics of the N-body system.
Finally, we describe the future work that will be done with these codes, mainly
the study of the adiabatic growth of a black hole at the center of a spherical
distribution of stars.


title: Extended Born-Infeld Dynamics and Cosmology

abstract:
  We introduce an extension of the Born-Infeld action for a scalar field and
show that it can act as unifying-dark-matter, providing an explanation for both
structure formation and the accelerated expansion of the universe. We
investigate the cosmological dynamics of this theory in a particular case,
referred as the "Milne-Born-Infeld" (MBI) Lagrangian. We show that this model,
whose equation of state has effectively a single free parameter, is consistent
with recent type Ia supernovae data, providing a fit as good as for the
$\Lambda$CDM model with the same number of degrees of freedom. Furthermore,
this parameter is tightly constrained by current data, making the model easily
testable with other observables. Contrary to previous candidates for
unifying-dark-matter, the sound velocity of the MBI model is vanishing both
close to the dark matter state as well as near the cosmological constant state.
This could avoid the problems on the matter power spectrum that were present in
previous adiabatic dark-matter/dark-energy unification models. We also present
a short discussion on the causal propagation in nonlinear scalar field theories
such as the one proposed here.


title:
Relative Evolutionary Time Scale of Hot Molecular Cores with Respect to
  Ultra Compact HII Regions

abstract:
  Using the Owens Valley and Nobeyama Radio Observatory interferometers, we
carried out an unbiased search for hot molecular cores and ultracompact UC HII
regions toward the high-mass star forming region G19.61--0.23. In addition, we
performed 1.2 mm imaging with SIMBA, and retrieved 3.5 and 2 cm images from the
VLA archive data base. The newly obtained 3 mm image brings information on a
cluster of high-mass (proto)stars located in the innermost and densest part of
the parsec scale clump detected in the 1.2 mm continuum. We identify a total of
10 high-mass young stellar objects: one hot core (HC) and 9 UC HII regions,
whose physical parameters are obtained from model fits to their continuum
spectra. The ratio between the current and expected final radii of the UC \HII
regions ranges from 0.3 to 0.9, which leaves the possibility that all O-B stars
formed simultaneously. Under the opposite assumption -- namely that star
formation occurred randomly -- we estimate that HC lifetime is less than
$\sim$1/3 of that of UCHII regions on the basis of the source number ratio
between them.


title: Gamma-ray Observations of Explosive Nucleosynthesis Products

abstract:
  In this review I discuss the various gamma-ray emission lines that are
expected and have been observed from radioactive explosive nucleosynthesis
products. The most important gamma-ray lines result from the decay chains of
Ni-56, Ni-57, and Ti-44. Ni-56 is the prime explosive nucleosynthesis product
of Type Ia supernovae, but Ni-56 is also a product of core-collapse supernovae.
Gamma-ray line emission from its daughter product, Co-56, has been detected
from SN1987A. The early occurrence of this emission indicates that some
fraction of Ni-56, which is synthesized in the innermost supernova layers, must
have mixed with the outermost ejecta.
  Special attention is given to the gamma-ray line emission of the decay chain
of Ti-44, giving line emission at 68 keV, 78 keV, and 1157keV. Given its decay
time of 86 yr, one expects this line emission from young supernova remnants.
The Ti-44 production is very sensitive to the explosion properties This makes
Ti-44 an ideal tool to study the inner layers of the supernova explosion.
  The gamma-ray line emission from Ti-44 has so far only been detected from the
supernova remnant Cas A. I discuss these detections, which were made by COMPTEL
and BeppoSAX, which suggest a Ti-44 yield of (1.5+/-1.0)x10^{-4} Msun.
Moreover, I present some preliminary results of Cas A observations by INTEGRAL,
which has yielded a 3sigma detection of the 68 keV line with the ISGRI
instrument at a level consistent with the BeppoSAX results. A preliminary
analysis of the vailable INTEGRAL-SPI data indicates that narrow line emission
(Delta v < 1000 km/s) can be almost excluded at the 2sigma level. (Abridged)


title:
Resolving IRAS 09111-1007 at 350 microns - a different path to ULIRG
  formation?

abstract:
  We have resolved the ultraluminous infrared galaxy (ULIRG), IRAS 09111-1007,
with the new 350 micron-optimised Second Generation Submillimeter High Angular
Resolution Camera (SHARC II) and present the first submillimetre fluxes and
images for the system. IRAS 09111-1007 comprises two interacting luminous
infrared galaxies (LIRGs) with a projected nuclear separation of 39 kpc. The
Western galaxy is roughly four times more luminous in the submillimetre than
its Eastern counterpart. It is an extremely bright LIRG with an AGN. The
classification of the Eastern source is uncertain: it could be a Seyfert 2
galaxy or a LINER. We highlight IRAS 09111-1007 as a system that necessitates
further study: a double AGN ULIRG whose molecular gas content differs from
other widely separated pairs and whose ULIRG phase might not be explained by
current multiple merger and/or final stage ULIRG scenarios.


title: Why Magnetic Fields Cannot be the Main Agent Shaping Planetary Nebulae

abstract:
  An increasing amount of literature reports the detection of magnetic fields
in asymptotic giant branch (AGB) stars and in central stars of planetary
nebulae (PNs). These detections lead to claims that the magnetic fields are the
main agent shaping the PNs. In this paper, I examine the energy and angular
momentum carried by magnetic fields expelled from AGB stars, as well as other
physical phenomena that accompany the presence of large scale fields, such as
those claimed in the literature. I show that a single star cannot supply the
energy and angular momentum if the magnetic fields have the large coherent
structure required to shape the circumstellar wind. Therefore, the structure of
non-spherical planetary nebulae cannot be attributed to dynamically important
large scale magnetic fields. I conclude that the observed magnetic fields
around evolved stars can be understood by locally enhanced magnetic loops which
can have a secondary role in the shaping of the PN. The primary role, I argue,
rests with the presence of a companion.


title: New Elemental Abundances for V1974 Cygni

abstract:
  We present a new analysis of existing optical and ultraviolet spectra of the
ONeMg nova V1974 Cygni 1992. Using these data and the photoionization code
Cloudy, we have determined the physical parameters and elemental abundances for
this nova. Many of the previous studies of this nova have made use of incorrect
analyses and hence a new study was required. Our results show that the ejecta
are enhanced, relative to solar, in helium, nitrogen, oxygen, neon, magnesium
and iron. Carbon was found to be subsolar. We find an ejected mass of ~2x10e-4
solar masses. Our model results fit well with observations taken at IR, radio,
sub-millimeter and X-ray wavelengths.


title:
A search for 53 MHz OH line near G48.4$-$1.4 using the National MST
  Radar Facility

abstract:
  We present the results of a search for the ground state hyperfine transition
of the OH radical near 53 MHz using the National MST Radar Facility at Gadanki,
India. The observed position was G48.4$-$1.4 near the Galactic plane. The OH
line is not detected. We place a 3$\sigma$ upper limit for the line flux
density at 39 Jy from our observations. We also did not detect recombination
lines (RLs) of carbon, which were within the frequency range of our
observations. The 3$\sigma$ upper limit of 20 Jy obtained for the flux density
of carbon RL, along with observations at 34.5 and 327 MHz are used to constrain
the physical properties of the line forming region. Our upper limit is
consistent with the line emission expected from a partially ionized region with
electron temperature, density and path lengths in the range 20 -- 300 K, 0.03
-- 0.3 cm$^{-3}$ and 0.1 -- 170 pc respectively.


title:
An 8.5 GHz Arecibo survey of Carbon Recombination Lines toward
  Ultra-compact \HII regions: Physical properties of dense molecular material

abstract:
  We report here on a survey of carbon recombination lines (RLs) near 8.5 GHz
toward 17 ultra-compact \HII regions (\UCHII s). Carbon RLs are detected in 11
directions, indicating the presence of dense photodissociation regions (PDRs)
associated with the \UCHII s. In this paper, we show that the carbon RLs
provide important, complementary information on the kinematics and physical
properties of the ambient medium near \UCHII s. Non-LTE models for the carbon
line forming region are developed, assuming that the PDRs surround the \UCHII
s, and we constrained the model parameters by multi-frequency RL data. Modeling
shows that carbon RL emission near 8.5 GHz is dominated by stimulated emission
and hence we preferentially observe the PDR material that is in front of the
\UCHII continuum. We find that the relative motion between ionized gas and the
associated PDR is about half that estimated earlier, and has an RMS velocity
difference of 3.3 \kms. Our models also give estimates for the PDR density and
pressure. We found that the neutral density of PDRs is typically $>$ 5 $\times$
10$^5$ \cmthree and \UCHII s can be embedded in regions with high ambient
pressure. Our results are consistent with a pressure confined \HII region model
where the stars are moving relative to the cloud core. Other models cannot be
ruled out, however. Interestingly, in most cases, the PDR pressure is an order
of magnitude larger than the pressure of the ionized gas. Further investigation
is needed to understand this large pressure difference.


title:
The Stable Topology of the Planetary Systems of two 2:1 Resonant
  Companions:Application to HD 82943

abstract:
  We have numerically explored the stable planetary geometry for the multiple
systems involved in a 2:1 mean motion resonance, and herein we mainly study the
HD 82943 system by employing two sets of the orbital parameters (Mayor et al.
2004; Ji et al. 2004). In the simulations, we find that all stable orbits are
related to the 2:1 resonance that can help to remain the semi-major axes for
two companions almost unaltered over the secular evolution for $10^{8}$ yr. In
addition, we also show that there exist three possible stable
configurations:(1) Type I, only $\theta_{1} \approx 0^{\circ}$, (2) Type II,
$\theta_{1}\approx\theta_{2}\approx\theta_{3}\approx 0^{\circ}$ (aligned case),
and (3) Type III, $\theta_{1}\approx 180^{\circ}$,
$\theta_{2}\approx0^{\circ}$, $\theta_{3}\approx180^{\circ}$ (antialigned
case), where two resonant arguments are $\theta_{1} = \lambda_{1} - 2\lambda
_{2} + \varpi_{1}$ and $\theta_{2} = \lambda_{1} - 2\lambda_{2} + \varpi_{2}$,
the relative apsidal longitudes $\theta_{3} =
\varpi_{1}-\varpi_{2}=\Delta\varpi$. And we find that other 2:1 resonant
systems (e.g., GJ 876) may possess one of three stable orbits in their
realistic motions. Moreover, we also study the existence of the assumed
terrestrial bodies at $\sim 1$ AU for HD 82943 and GJ 876 systems (see main
texts).


title: Two-field Models of Dark Energy with Equation of State Across -1

abstract:
  In this paper, we study the possibility of building two-field models of dark
energy with equation of state across -1. Specifically we will consider two
classes of models: one consists of two scalar fields (Quintessence+Phantom) and
another includes one scalar (Phantom) and one spinor field (Neutrino). Our
studies indicate to some extent that two-field models give rise to a simple
realization of the dynamical dark energy model with the equation of state
across $w = -1$.


title: Pycnonuclear reactions in dense stellar matter

abstract:
  We discuss pycnonuclear burning of highly exotic atomic nuclei in deep crusts
of neutron stars, at densities up to 1e13 g/cc. As an application, we consider
pycnonuclear burning of matter accreted on a neutron star in a soft X-ray
transient (SXT, a compact binary containing a neutron star and a low-mass
companion). The energy released in this burning, while the matter sinks into
the stellar crust under the weight of newly accreted material, is sufficient to
warm up the star and initiate neutrino emission in its core. The surface
thermal radiation of the star in quiescent states becomes dependent of poorly
known equation of state (EOS) of supranuclear matter in the stellar core, which
gives a method to explore this EOS. Four qualitatively different model EOSs are
tested against observations of SXTs. They imply different levels of the
enhancement of neutrino emission in massive neutron stars by (1) the direct
Urca process in nucleon/hyperon matter; (2) pion condensates; (3) kaon
condensates; (4) Cooper pairing of neutrons in nucleon matter with the
forbidden direct Urca process. A low level of the thermal quiescent emission of
two SXTs, SAX J1808.4-3658 and Cen X-4, contradicts model (4). Observations of
SXTs test the same physics of dense matter as observations of thermal radiation
from cooling isolated neutron stars, but the data on SXTs are currently more
conclusive.


title: A Galactic Plane Relative Extinction Map from 2MASS

abstract:
  We present three 14400 square degree relative extinction maps of the Galactic
Plane (|b|<20degrees) obtained from 2MASS using accumulative star counts (Wolf
diagrams). This method is independent of the colour of the stars and the
variation of extinction with wavelength. Stars were counted in 3.5'x3.5' boxes,
every 20". 1x1degree surrounding fields were chosen for reference, hence the
maps represent local extinction enhancements and ignore any contribution from
the ISM or very large clouds. Data reduction was performed on a Beowulf-type
cluster (in approximately 120 hours). Such a cluster is ideal for this type of
work as areas of the sky can be independently processed in parallel. We studied
how extinction depends on wavelength in all of the high extinction regions
detected and within selected dark clouds. On average a power law opacity index
(\beta) of 1.0 to 1.8 in the NIR was deduced. The index however differed
significantly from region to region and even within individual dark clouds.
That said, generally it was found to be constant, or to increase, with
wavelength within a particular region.


title:
Three-dimensional Numerical Simulations of Rayleigh-Taylor Unstable
  Flames in Type Ia Supernovae

abstract:
  Flame instabilities play a dominant role in accelerating the burning front to
a large fraction of the speed of sound in a Type Ia supernova. We present a
three-dimensional numerical simulation of a Rayleigh-Taylor unstable carbon
flame, following its evolution through the transition to turbulence. A low Mach
number hydrodynamics method is used, freeing us from the harsh timestep
restrictions imposed by sound waves. We fully resolve the thermal structure of
the flame and its reaction zone, eliminating the need for a flame model. A
single density is considered, $1.5\times 10^7 \gcc$, and half carbon\slash half
oxygen fuel--conditions under which the flame propagated in the flamelet regime
in our related two-dimensional study. We compare to a corresponding
two-dimensional simulation, and show that while fire-polishing keeps the small
features suppressed in two dimensions, turbulence wrinkles the flame on far
smaller scales in the three-dimensional case, suggesting that the transition to
the distributed burning regime occurs at higher densities in three dimensions.
Detailed turbulence diagnostics are provided. We show that the turbulence
follows a Kolmogorov spectrum and is highly anisotropic on the large scales,
with a much larger integral scale in the direction of gravity. Furthermore, we
demonstrate that it becomes more isotropic as it cascades down to small scales.
Based on the turbulent statistics and the flame properties of our simulation,
we compute the Gibson scale. We show the progress of the turbulent flame
through a classic combustion regime diagram, indicating that the flame just
enters the distributed burning regime near the end of our simulation.


title:
The Physical Connections Among IR QSOs, PG QSOs and Narrow-Line Seyfert
  1 Galaxies

abstract:
  We study the properties of infrared-selected QSOs (IR QSOs),
optically-selected QSOs (PG QSOs) and Narrow Line Seyfert 1 galaxies (NLS1s).
We compare their properties from the infrared to the optical and examine
various correlations among the black hole mass, accretion rate, star formation
rate and optical and infrared luminosities. We find that the infrared excess in
IR QSOs is mostly in the far infrared, and their infrared spectral indices
suggest that the excess emission is from low temperature dust heated by
starbursts rather than AGNs. The infrared excess is therefore a useful
criterion to separate the relative contributions of starbursts and AGNs. We
further find a tight correlation between the star formation rate and the
accretion rate of central AGNs for IR QSOs. The ratio of the star formation
rate and the accretion rate is about several hundred for IR QSOs, but decreases
with the central black hole mass. This shows that the tight correlation between
the stellar mass and the central black hole mass is preserved in massive
starbursts during violent mergers. We suggest that the higher Eddington ratios
of NLS1s and IR QSOs imply that they are in the early stage of evolution toward
classical Seyfert 1's and QSOs, respectively.


title:
On the influence of Stark broadening on Cr I lines in stellar
  atmospheres

abstract:
  Using the semiclassical perturbation method, electron-, proton-, and ionized
helium-impact line widths and shifts for the nine Cr I spectral lines from the
$4p^7P^0-4d^7D$ multiplet, have been calculated for a perturbers density of
10$^{14}$ cm$^{-3}$ and temperatures T =2,500 - 50,000 K. The obtained results
have been used to investigate the influence of Stark broadening effect in the
Cr-rich Ap star $\beta $ CrB atmosphere on line shapes of these lines. It has
been found that the contribution of the proton and He II collisions to the line
width and shift is significant, and it is comparable and sometimes (depending
of the electron temperature) even larger than electron-impact contribution.
Moreover, not only the Stark line width, but, depending on the electron-,
proton-, and He\ii density in stellar atmosphere also the Stark shift may
contribute to the blue as well as to the red asymmetry of the same line. The
obtained results have been used to investigate the influence of Stark
broadening effect on line shapes of Cr\i lines in the atmosphere of Cr-rich Ap
star $\beta $ CrB.


title: Binary Black Holes at the Core of Galaxy Clusters

abstract:
  In this paper we push forward and exploit an analogy between the morphologies
of the X-ray cavities observed in some galaxy clusters, and the optically
deficient point-symmetric bubbles occurring in some planetary nebulae (PNe).
Point-symmetric PNe are thought to be shaped by stellar binary interactions;
namely, the presence of a companion to the PN's progenitor star is required. We
suggest that similar point-symmetric structures in the X-ray cavities of galaxy
clusters might be associated with the presence of massive binary black holes. A
systematic cataloguing of high-resolution images of the diffuse X-ray emission
at the core of galaxy clusters might contribute to individuate massive binary
black holes.


title:
From the Spectrum to Inflation : An Inverse Formula for the General
  Slow-Roll Spectrum

abstract:
  We propose a general inverse formula for extracting inflationary parameters
from the observed power spectrum of cosmological perturbations. Under the
general slow-roll scheme, which helps to probe the properties of inflation in a
model independent way, we invert the leading order, single field, power
spectrum formula. We also give some physically interesting examples to
demonstrate its wide applicability and illuminate its properties.


title: Radio Observations of PSR B1259-63 through the 2004 periastron passage

abstract:
  We report here on extensive radio observations of the binary system
containing PSR B1259-63 and the Be star SS 2883, made around the time of the
2004 periastron. This is the fourth periastron to have been observed in detail.
As in previous observations, changes in the pulsar's dispersion and rotation
measures are detected over a period spanning 200 days. We show that the eclipse
of the pulsed emission lasts from 16 days prior to periastron to 15 days after
periastron and is consistent from one periastron to the next. We demonstrate
that the timing solution proposed by Wang et al. (2004) provides a good fit
through the 2004 periastron. The light curve of the transient unpulsed radio
emission is broadly similar from one periastron to the next. For this
periastron, however, the light curve is strongly peaked post-periastron with
rather little enhancement prior to periastron, in contrast to the 2000
periastron where the peak flux densities were more equal. These observations
remain consistent with the interpretation that the pulsar passes through the
dense circumstellar disk of the Be star just before and just after periastron.
The observed differences from one periastron to the next can be ascribed to
variations in the local disk density and magnetic field structure at the time
the pulsar enters the disk.


title: Classifying the Future of Universes with Dark Energy

abstract:
  We classify the future of the universe for general cosmological models
including matter and dark energy. If the equation of state of dark energy is
less then -1, the age of the universe becomes finite. We compute the rest of
the age of the universe for such universe models. The behaviour of the future
growth of matter density perturbation is also studied. We find that the
collapse of spherical overdensity region is greatly changed if the equation of
state of dark energy is less than -1.


title:
The non-detection of oscillations in Procyon by MOST: is it really a
  surprise?

abstract:
  We argue that the non-detection of oscillations in Procyon by the MOST
satellite reported by Matthews et al. (2004) is fully consistent with published
ground-based velocity observations of this star. We also examine the claims
that the MOST observations represent the best photometric precision so far
reported in the literature by about an order of magnitude and are the most
sensitive data set for asteroseismology available for any star other than the
Sun. These statements are not correct, with the most notable exceptions being
observations of oscillations in alpha Cen A that are far superior. We further
disagree that the hump of excess power seen repeatedly from velocity
observations of Procyon can be explained as an artefact caused by gaps in the
data. The MOST observations failed to reveal oscillations clearly because their
noise level is too high, possibly from scattered Earthlight in the instrument.
We did find an excess of strong peaks in the MOST amplitude spectrum that is
inconsistent with a simple noise source such as granulation, and may perhaps
indicate oscillations at roughly the expected level.


title:
Relativistic second-order perturbations of nonzero-\Lambda flat
  cosmological models and CMB anisotropies

abstract:
  First the second-order perturbations of nonzero-\Lambda cosmological models
are derived with an arbitrary potential function of spatial coordinates, using
the nonlinear version of Lifshitz's method in the synchronous gauge. Their
expression is the generalization (to the nonzero-\Lambda case) of second-order
perturbations in the Einstein-de Sitter model which were derived previously by
the present author. Next the second-order temperature anisotropies of Cosmic
Micriwave Background radiation are derived using the gauge-invariant formula
which was given by Mollerach and Matarrese. Moreover the corresponding
perturbations in the Poisson gauge are derived using the second-order gauge
transformations formulated by Bruni et al. In the second-order it is found in
spite of gauges that tensor (gravitational-wave) perturbations and vector
(shear) perturbations without vorticity are induced from the first-order scalar
perturbations. These results will be useful to analyze the nonlinear effect of
local inhomogeneities on Cosmic Microwave Background anisotropies.


title:
Reddening, Absorption, and Decline Rate Corrections for a Complete
  Sample of Type Ia Supernovae leading to a Fully Corrected Hubble Diagram to
  v<30,000kms-1

abstract:
  Photometric BVI and redshift data corrected for streaming motions are
compiled for 111 "Branch normal", 4 1991T-like, 7 1991bg-like, and 2 unusual
SNe Ia. Color excesses E(B-V)host of normal SNe Ia, due to the absorption of
the host galaxy, are derived by three independent methods leading to the
intrinsic colors at maximum of (B-V)00=-0.024, and (V-I)00=-0.265 if normalized
to a common decline rate of Dm_15=1.1. The strong correlation between redshift
absolute magnitudes (based on Ho=60), corrected only for the extrinsic Galactic
absorption, and the derived E(B-V)host leads to well determined, yet abnormal
absorption-to-reddening ratios of R_BVI=3.65, 2.65, and 1.35. Comparison with
the canonical Galactic values of 4.1, 3.1, 1.8 forces the conclusion that the
law of interstellar absorption in the path length to the SN in the host galaxy
is different from the local Galactic law. Improved correlations of the fully
corrected absolute magnitudes with host galaxy type, decline rate, and
intrinsic color are derived. The four peculiar 1991T-type SNe are significantly
overluminous as compared to Branch-normal SNe Ia. The overluminosity of the
seven 1999aa-like SNe is less pronounced. The seven 1991bg-types in the sample
constitute a separate class of SNeIa, averaging in B two magnitudes fainter
than the normal Ia. New Hubble diagrams in BVI are derived out to ~30,000kms-1
using the fully corrected magnitudes and velocities, corrected for streaming
motions. Nine solutions for the intercept magnitudes in these diagrams show
extreme stability at the 0.04 level using various subsamples of the data. The
same precepts for fully correcting SN magnitudes we shall use for the
luminosity recalibration of SNe Ia in the forthcoming final review of our HST
Cepheid-SN experiment for the Hubble constant.


title: The Mean Pulse Profile of PSR J0737-3039A

abstract:
  General relativity predicts that the spin axes of the pulsars in the
double-pulsar system (PSR J0737-3039A/B) will precess rapidly, in general
leading to a change in the observed pulse profiles. We have observed this
system over a one-year interval using the Parkes 64-m radio telescope at three
frequencies: 680, 1390 and 3030 MHz. These data, combined with the short survey
observation made two years earlier, show no evidence for significant changes in
the pulse profile of PSR J0737-3039A, the 22-ms pulsar. The limit on variations
of the profile 10% width is about 0.5 deg per year. These results imply an
angle delta between the pulsar spin axis and the orbit normal of <~ 60 deg,
consistent with recent evolutionary studies of the system. Although a wide
range of system parameters remain consistent with the data, the model proposed
by Jenet & Ransom (2004) can be ruled out. A non-zero ellipticity for the
radiation beam gives slightly but not significantly improved fits to the data,
so that a circular beam describes the data equally well within the
uncertainties.


title: Modeling the Dust Spectral Energy Distributions of Dwarf Galaxies

abstract:
  Recent efforts on the modeling of the infrared spectral energy distributions
(SEDs) of dwarf galaxies are summarised here. The characterisation of the dust
properties in these low metallicity environments is just unfolding, as a result
of recently available mid-infrared to millimetre observations. From the limited
cases we know to date, it appears that the hard radiation fields that are
present in these star-bursting dwarf galaxies, as well as the rampent
energetics of supernovae shocks and winds have modified the dust properties, in
comparison with those in the Galaxy, or other gas and dust rich galaxies. The
sophistication of the SED models is limited by the availability of detailed
data in the mid infrared and particularly in the submillimetre to millimetre
regime, which will open up in the near future with space-based missions, such
as Herschel.


title:
The unidentified TeV source (TeVJ2032+4130) and surrounding field: Final
  HEGRA IACT-System results

abstract:
  The unidentified TeV source in Cygnus is now confirmed by follow-up
observations from 2002 with the HEGRA stereoscopic system of Cherenkov
Telescopes. Using all data (1999 to 2002) we confirm this new source as steady
in flux over the four years of data taking, extended with radius 6.2 arcmin
(+-1.2 arcmin (stat) +-0.9 arcmin (sys)) and exhibiting a hard spectrum with
photon index -1.9. It is located in the direction of the dense OB stellar
association, Cygnus OB2. Its integral flux above energies E>1 TeV amounts to
\~5% of the Crab assuming a Gaussian profile for the intrinsic source
morphology. There is no obvious counterpart at radio, optical nor X-ray
energies, leaving TeVJ2032+4130 presently unidentified. Observational
parameters of this source are updated here and some astrophysical discussion is
provided. Also included are upper limits for a number of other interesting
sources in the FoV, including the famous microquasar Cygnus X-3.


title: The end of locked inflation

abstract:
  We investigate the end of the inflationary period in the recently proposed
scenario of locked inflation, and consider various constraints arising from
density perturbations, loop corrections, parametric resonance and defect
formation. We show that in a scenario where there is one long period of locked
inflation, it is not possible to satisfy all of these constraints without
having a period of saddle inflation afterwards, which would wipe out all
observable signatures. On the other hand, if one does not insist on satisfying
the loop correction constraint, saddle inflation can be avoided, but then
inflation must have ended through parametric resonance.


title:
Is Arcturus a well-understood K giant? Test of model atmospheres and
  potential companion detection by near-infrared interferometry

abstract:
  We present near-IR interferometric measurements of the K1.5 giant Arcturus
(alpha Bootis), obtained at the IOTA interferometer with the FLUOR instrument,
in four narrow filters with central wavelengths ranging from 2.03 to 2.39
micron. These observations were expected to allow us to quantify the wavelength
dependence of the diameter of a typical K giant. They are compared to
predictions from both plane-parallel and spherical model atmospheres.
Unexpectedly, neither can explain the observed visibilities. We show how these
data suggest the presence of a companion, in accordance with the Hipparcos data
on this star, and discuss this solution with respect to Arcturus' single star
status.


title:
On the Light Curve and Spectrum of SN 2003dh Separated from the Optical
  Afterglow of GRB 030329

abstract:
  The net optical light curves and spectra of the supernova (SN) 2003dh are
obtained from the published spectra of GRB 030329, covering about 6 days before
SN maximum to about 60 days after. The bulk of the U-band flux is subtracted
from the observed spectra using early-time afterglow templates, because strong
line blanketing greatly depresses the UV and U-band SN flux in a metal-rich,
fast-moving SN atmosphere. The blue-end spectra of the gamma-ray burst
(GRB)connected hypernova SN 1998bw is used to determine the amount of
subtraction. The subtraction of a host galaxy template affects the late-time
results. The derived SN 2003dh light curves are narrower than those of SN
1998bw, rising as fast before maximum, reaching a possibly fainter maximum, and
then declining ~ 1.2-1.4 times faster. We then build UVOIR bolometric SN light
curve. Allowing for uncertainties, it can be reproduced with a spherical ejecta
model of Mej ~ 7+/-3 Msun, KE ~ (3.5+/-1.5)E52 ergs, with KE/Mej ~ 5 following
previous spectrum modelling, and M(Ni56) ~ (0.4 +0.15/-0.1) Msun. This suggests
a progenitor main-sequence mass of about 25-40 Msun, lower than SN 1998bw but
significantly higher than normal Type Ic SNe and the GRB-unrelated hypernova SN
2002ap.


title: Direct Evidence for a Polar Spot on SV Cam

abstract:
  We have used spectrophotometric data from the Hubble Space Telescope to
eclipse-map the primary component of the RS CVn binary SV Cam over 9 HST
orbits. We find from these observations and the HIPPARCOS parallax that the
surface flux in the eclipsed low-latitude region of the primary is about 30%
lower than computed from a PHOENIX model atmosphere at the effective
temperature that best fits the spectral energy distribution of the eclipsed
flux. This can only be accounted for if about a third of the primary's surface
is covered with unresolved dark star-spots. Extending this to the full surface
of the primary, we find that even taking into account this spot filling factor
there is an additional flux deficit on the primary star. This can only be
explained if there is a large polar spot on the primary star extending from the
pole to latitude 48 degrees.


title:
Dynamics of the Primordial Hydrogen and Helium (HeI) Recombination in
  the Universe

abstract:
  The dependences on z of fractional number densities of H+ and He+ ions are
calculated with a proper allowance for two-photon decays of upper levels of
hydrogen and parahelium and radiative transfer in intercombination line 2 3P_1
--> 1 1S_0 of helium. It is shown that for hydrogen this gives corrections for
a degree of ionization in no more than a few percents but for helium this leads
to a significant acceleration of recombination compared to the recent papers by
Seager et al. (1999; 2000) where these effects were ignored.


title: Leading Wave as a Component of the Spiral Pattern of the Galaxy

abstract:
  The spiral pattern of the Galaxy identified by analyzing the kinematics of
young stars within 3 kpc of the Sun is Fourier decomposed into spiral
harmonics. The spiral pattern of the Galaxy is shown to be representable as a
superposition of trailing and leading waves with interarm distances of
1.8(+/-0.4) kpc and 4(+/-2) kpc, respectively. Shock waves are probably present
only in the portions of the trailing spiral pattern where it crosses the crest
of the leading wave. The small interarm distance of the trailing spiral wave
(1.8 kpc) can be explained by its evolution - by the decrease in the interarm
distance as the wave is displaced toward the inner Lindblad resonance. The
Carina arm may be part of this resonance ring.


title: Astrophysical parameters of Galactic open clusters

abstract:
  We present a catalogue of astrophysical data of 520 Galactic open clusters.
These are the clusters, for which at least three most probable members (18 on
average) could be identified in the ASCC-2.5, a catalogue of stars based on the
Tycho-2 observations from the Hipparcos mission. We applied homogeneous methods
and algorithms to determine angular sizes of cluster cores and coronae,
heliocentric distances, mean proper motions, mean radial velocities and ages.
For the first time we derive distances for 200 clusters, radial velocities for
94 clusters and determine ages of 196 clusters. This homogeneous new parameter
set is compared with earlier determinations. In particular, we find that the
angular sizes were systematically underestimated in the literature.


title:
Cardassian Expansion: Dark Energy Density from Modified Friedmann
  Equations

abstract:
  The Cardassian universe is a proposed modification to the Friedmann equation
in which the universe is flat, matter dominated, and accelerating. In the
ordinary Friedmann equation, the right hand side is a linear function of the
energy density, $H^2 \sim \rho$. Here, instead, the right hand side of the
Friedmann equation is a different function of the energy density, $H^2 \sim
g(\rho)$. This function returns to ordinary Friedmann at early times, but
drives acceleration of the universe at the current epoch. The only ingredients
in this universe are matter and radiation: in particular, there is NO vacuum
contribution. The new term required may arise, e.g., as a consequence of our
observable universe living as a 3-dimensional brane in a higher dimensional
universe. A second possible interpretation of Cardassian expansion is
developed, in which we treat the modified Friedman equations as due to a fluid,
in which the energy density has new contributions with negative pressure
(possibly due to dark matter with self-interactions). Predictions are shown for
observational tests of generalized Cardassian models in future supernova
surveys.


title:
Constraining the structure of the non-spherical preprotostellar core
  L1544

abstract:
  A series of self-consistent, three-dimensional continuum radiative transfer
models are constructed of the pre-protostellar core L1544, with the results
compared with existing SCUBA and ISO data. The source is well-fit by a prolate
spheroid, having an ellipsoidal power-law density distribution of index m ~ 2
(1.75 < m < 2.25) in to at least r ~ 1600AU. For r<1600 AU, the data are
consistent with either an extension of the power law to smaller radii, or a
flattened (Bonner-Ebert like) density distribtion. We can further constrain the
optical depth along the short axis at 1300um to be ~ 5e-3, the central
luminosity to be L < 1e-3 solar luminosities, the long axis diameter D ~ 0.1
pc, the axis ratio to be q ~ 2, and the external ISRF to be similar to that
defined by Mathis, Mezger, & Panagia (1983) to within 50 per cent. The outer
diameter and axis ratio may each be somewhat larger due to potential on-source
chopping in the observations, and the projection of the long axis onto the
plane of the sky. While these results are similar to those inferred directly
from observations or spherical modeling due to the source transparency at
submillimeter wavelengths, we infer a smaller size, lower mass, and higher
optical depth / column density, exposed to a stronger external radiation field
than previously assumed. Finally, we find that both the spectral energy
distribution (SED) and surface brightness distribution are necessary to
constrain the source properties in this way.


title:
Blind search for the real sample: Application to the origin of
  ultra-high energy cosmic rays

abstract:
  We suggest a method for statistical tests which does not suffer from a
posteriori manipulations with tested samples (e.g. cuts optimization) and does
not require a somewhat obscure procedure of the penalty estimate. The idea of
the method is to hide the real sample (before it has been studied) among a
large number of artificial samples, drawn from a random distribution expressing
the null hypothesis, and then to search for it as the one demonstrating the
strongest hypothesized effect. The statistical significance of the effect in
this approach is the inverse of the maximal number of random samples at which
the search was successful. We have applied the method to revisit the problem of
correlation between the arrival directions of ultra-high energy cosmic rays and
BL Lac objects. No significant correlation was found.


title: Cooling of Neutron Stars and 3P_2 neutron gap

abstract:
  We study the dependence of the cooling of isolated neutron stars on the
magnitude of the $3P_2$ neutron gap. It is demonstrated that our ``Nuclear
medium cooling scenario'' is in favor of a suppressed value of the $3P_2$
neutron gap.


title:
High Resolution Studies of Radio Sources in the Hubble Deep and Flanking
  Fields

abstract:
  Eighteen days of MERLIN data and 42 hours of A-array VLA data at 1.4 GHz have
been combined to image a 10-arcmin field centred on the Hubble Deep and
Flanking Fields (HDF and HFF). A complete sample of 92 radio sources with
1.4-GHz flux densities above 40 microJy has been imaged using MERLIN+VLA. The
images are amongst the most sensitive yet made at 1.4 GHz, with rms noise
levels of 3.3 microJy/beam in the 0.2-arcsec images. Virtually all the sources
are resolved, with angular sizes in the range 0.2 to 3 arcsec. No additional
sources were detected down to 23 microJy in the central 3 arcmin, indicating
that sources fainter than 40 microJy are heavily resolved with MERLIN and must
have typical angular sizes greater than 0.5 arcsec. Compact radio sources were
used to align the optical data to the ICRF, to <50 mas in the HDF. We find a
statistical association of very faint (2 microJy and above) radio sources with
optically bright HDF galaxies down to about 23 mag. Of the 92 radio sources
above 40 microJy, about 85 percent are identified with galaxies brighter than
about I = 25 mag; the remaining 15 percent are associated with optically faint
systems. We identify several very red, optically faint systems including the
the strongest sub-mm source in the HDF, HDF850.1. 72 percent of the radio
sources are starburst or AGN-type systems; the remainder are unclassified. The
proportion of starburst systems increases with decreasing flux density; below
100 microJy 70 percent of the sources are starburst-type systems in the
redshift range 0.3 -- 1.3. Chandra detections are associated with 55 of the 92
radio sources but their X-ray flux densities do not appear to be correlated
with the radio flux densities or morphologies.


title:
Massive galaxies & EROs at z=1-3 in cosmological hydrodynamic
  simulations: near-IR properties

abstract:
  Recent observations have revealed a population of red massive galaxies at
high redshift which are challenging to explain in hierarchical galaxy formation
models. We analyze this ``massive galaxy problem'' with two different types of
hydrodynamic simulations -- Eulerian TVD and SPH -- of a concordance Lambda CDM
universe. We consider two separate but connected aspects of the problem posed
by these extremely red objects (EROs): (1) the mass-scale, and (2) red colors.
We perform spectrophotometric analyses of simulated galaxies in B, z, R, I, Js,
Ks, K filters, and compare their near-IR properties with observations at
redshift z=1-3. We find that the simulated galaxies brighter than the magnitude
limit of K_vega=20 mag have stellar masses Mstar >= 10^{11} Msun/h and a number
density of a few \times 10^{-4} h^3 Mpc^{-3} at z~2, in good agreement with the
observed number density in the K20 survey. Therefore, our hydrodynamic
simulations do not exhibit the ``mass-scale problem''. The answer to the
``redness problem'' is less clear because of our poor knowledge of the amount
of dust extinction in EROs and the uncertain fraction of star-forming EROs.
However, our simulations can account for the observed comoving number density
of ~ 1e-4 Mpc^{-3} at z=1-2 if we assume a uniform extinction of E(B-V)=0.4 for
the entire population of simulated galaxies. The critical question of the
existence of a significant population of old, passively evolving massive EROs
should continue to be tested with future hydrodynamic simulations. Upcoming
observations of the thermal emission of dust in 24 micron by the Spitzer Space
Telescope will help to better estimate the dust content of EROs at z=1-3, and
thus to further constrain the star formation history of the Universe, and
theoretical models of galaxy formation. (abridged)


title:
Resonant Auger Destruction and Iron K-Alpha Spectra in Compact X-ray
  Sources

abstract:
  We examine the effects of resonant Auger destruction in modifying the
intensities and flux distributions of K-alpha spectra from iron L-shell ions.
Applications include X-ray irradiated stellar winds in X-ray binaries and
accretion disk atmospheres. Using detailed atomic models, we find that resonant
Auger destruction is selective, in that only a subset of the emitted K-alpha
lines is highly attenuated. We also show that that the local excitation
conditions can have a dramatic effect on the K-alpha emissivity spectrum.


title: Reducing the shear

abstract:
  As gravitational lensing measurements become increasingly precise, it becomes
necessary to include ever higher order effects in the theoretical calculations.
Here we show how the difference between the shear and the reduced shear
manifest themselves in a number of commonly used measures of shear power. If we
are to reap the science rewards of future, high precision measurements of
cosmic shear we will need to include this effect in our theoretical
predictions.


title: Ultraviolet HST Observations of the Jet in M87

abstract:
  We present new ultraviolet photometry of the jet in M87 obtained from HST
WFPC2 imaging. We combine these ultraviolet data with previously published
photometry for the knots of the jet in radio, optical, and X-ray, and fit three
theoretical synchrotron models to the full data set. The synchrotron models
consistently overpredict the flux in the ultraviolet when fit over the entire
dataset. We show that if the fit is restricted to the radio through ultraviolet
data, the synchrotron models can provide a good match to the data. The break
frequencies of these fits are much lower than previous estimates. The implied
synchrotron lifetimes for the bulk of the emitting population are longer than
earlier work, but still much shorter than the estimated kinematic lifetimes of
the knots. The observed X-ray flux cannot be successfully explained by the
simple synchrotron models that fit the ultraviolet and optical fluxes. We
discuss the possible implications of these results for the physical properties
of the M87 jet. We also observe increased flux for the HST-1 knot that is
consistent with previous results for flaring. This observation fills in a
significant gap in the time coverage early in the history of the flare, and
therefore sets constraints on the initial brightening of the flare.


title:
The formation and evolution of hydrogen-deficient post-AGB white dwarfs:
  the emerging chemical profile and the expectations for the PG1159-DB-DQ
  evolutionary connection

abstract:
  This paper is designed to explore the formation and evolution of
hydrogen-deficient post-AGB white dwarfs. To this end, we compute the complete
evolution of an initially 2.7 M_sun star from the zero-age main sequence
through the thermally pulsing and mass-loss phases to the white dwarf stage.
Particular attention is given to the chemical abundance changes during the
whole evolution. A time-dependent scheme for the simultaneous treatment of
abundance changes caused by nuclear reactions, diffusive overshooting, salt
fingers and convection is considered. We employed the double-diffusive
mixing-length theory of convection for fluids with composition gradients
(Grossman & Taam 1996). The study can therefore be considered as a test of its
performance in low-mass stars. Also, time-dependent element diffusion for
multicomponent gases is taken into account during the white dwarf evolution.
The evolutionary stages corresponding to the last helium thermal pulse on the
early white-dwarf cooling branch and the following born-again episode are
carefully explored. Relevant aspects for PG1159 stars and DB white dwarf
evolution are studied in the frame of these new evolutionary models that take
into account the history of the white dwarf progenitor. The scope of the
calculations is extended to the domain of the helium-rich, carbon-contaminated
DQ white dwarfs with the aim of exploring the plausibility of the evolutionary
connection PG1159-DB-DQ. In this regard, the implications for the
double-layered chemical structure in pulsating DB white dwarfs is investigated.
Another aspect of the investigation concerned the consequences of mass-loss
episodes during the PG1159 stage for the chemical stratification of the outer
layer of DB and DQ white dwarfs.


title: Recurrent ~24 h Periods in RXTE ASM Data

abstract:
  Analysis of data from the Rossi X-ray Timing Explorer satellite's All Sky
Monitor instrument for several X-ray binary sources has identified a recurrent
\~24 h period. This period is sometimes highly significant, giving rise to the
possibility of it being identified as an orbital or super-orbital period.
Further analysis has revealed the same period in a number of other X-ray
sources. As a result this period has been discounted as spurious, described
variously as arising from daily variations in background levels and beating
between the sampling period and long-term secular trends in the light curves.
We present here an analysis of the spurious periods and show that the dominant
mechanism is in fact spectral leakage of low-frequency power present in the
light curves.


title: Chandra Observations of Gravitational Lenses B1600+434 and B1608+656

abstract:
  We observed B1600+434 and B1608+656 with CXO/ACIS, detecting both quasar
images in B1600+434 and three of four images in B1608+656. We did not detect
significant X-ray emission from nearby galaxy groups or clusters associated
with each lens galaxy. The upper limits on the X-ray luminosity of any cluster
within 4 arcmin of each lens and at each lens redshift are of ~2\times10^{42}
and ~6\times10^{42} erg/s for B1600+434 and B1608+656, respectively. The
radio-loud source quasars have power-law photon indices of \Gamma=1.9\pm0.2 and
\Gamma=1.4\pm0.3 and X-ray luminosities of 1.4^{+0.2}_{-0.1}\times10^{45} and
2.9^{+0.7}_{-0.4}\times10^{44} erg/s for B1600+434 and B1608+656, respectively
before correcting for the magnification. We detected a differential absorption
column density of \Delta N_H ~ 3\times10^{21} cm^{-2} between the two images of
B1600+434, roughly consistent with expectations from differential extinction
estimates of \Delta E(B-V)=0.1 mag and a standard dust-to-gas ratio. The
differential absorption observed in gravitational lenses may serve as an
important probe to study the gas content in high redshift galaxies since it can
separate the absorbing column originating from the lens galaxy and those
intrinsic to quasars. We also detected 157 serendipitous X-ray sources in the
two Chandra fields and identified the brighter optical counterparts using the
SDSS and DPOSS surveys.


title: Superorbital Period in the High Mass X-ray Binary 2S 0114+650

abstract:
  We report the detection of a superorbital period in the high-mass X-ray
binary 2S 0114+650. Analyses of data from the Rossi X-ray Timing Explorer
(RXTE) All-Sky Monitor (ASM) from 1996 January 5 to 2004 August 25 reveal a
superorbital period of 30.7 +/- 0.1 d, in addition to confirming the previously
reported neutron star spin period of 2.7 h and the binary orbital period of
11.6 d. It is unclear if the superorbital period can be ascribed to the
precession of a warped accretion disc in the system.


title: A multiwavelength study of the remnant of nova GK Persei

abstract:
  We present new observations of the nebular remnant of the old nova GK Persei
1901, in the optical using the 2m HCT and at low radio frequencies using the
GMRT. The evolution of the nova remnant indicates shock interaction with the
ambient medium, especially in the southwest quadrant. Application of a simple
model for the shock and its evolution to determine the time dependence of the
radius of the shell in the southwest quadrant indicates that the shell is now
expanding into an ambient medium that has a lower density compared to the
density of the ambient medium ahead of the shock in 1987.There are indications
of a recent interaction of the nova remnant with the ambient medium in the
northeast quadrant also. The nova remnant of GK Per is detected at all the
observed radio frequencies and is of similar extent as the optical remnant.
Putting together our radio observations with VLA archival data on GK Per from
1997, we obtain three interesting results: 1. The spectrum above 1.4 GHz
follows a power law with an index -0.7 and below 1.4 GHz follows a power law
with an index ~ -0.85. This could be due to the presence of at least two
populations of electrons dominating the global emission at different
frequencies. 2. We record an annual secular decrease of 2.1% in the flux
density of the nova remnant at 1.4 and 4.9 GHz between 1984 and 1997 which has
left the spectral index unchanged at -0.7. No such decrease is observed in the
flux densities below 1 GHz. 3. We record an increase in the flux density at
0.33 GHz compared to the previous estimate in 1987. We conclude that the
remnant of nova GK Per is similar to supernova remnants and in particular, to
the young supernova remnant Cas A.


title:
Gamma-ray bursts and other sources of giant lightning discharges in
  protoplanetary systems

abstract:
  Lightning in the solar nebula is considered to be one of the probable sources
for producing the chondrules that are found in meteorites. Gamma-ray bursts
(GRBs) provide a large flux of gamma-rays that Compton scatter and create a
charge separation in the gas because the electrons are displaced from the
positive ions. The electric field easily exceeds the breakdown value of ~1 V
m^-1 over distances of order 0.1 AU. The energy in a giant lightning discharge
exceeds a terrestrial lightning flash by a factor of ~10^12. The predicted
post-burst emission of gamma-rays from accretion into the newly formed black
hole or spin-down of the magnetar is sufficiently intense to cause a lightning
storm in the nebula that lasts for days and is more probable than the GRB
because the radiation is beamed into a larger solid angle. The giant outbursts
from nearby soft gamma-ray repeater sources (SGRs) are also capable of causing
giant lightning discharges. The total amount of chondrules produced is in
reasonable agreement with the observations of meteorites. Furthermore in the
case of GRBs most chondrules were produced in a few major melting events by
nearby GRBs and lightning occurred at effectively the same time over the whole
nebula, and provide accurate time markers to the formation of chondrules and
evolution of the solar nebula. This model provides a reasonable explanation for
the delay between the formation of calcium aluminium inclusions (CAIs) and
chondrules.


title: Effelsberg HI observations of compact high-velocity clouds

abstract:
  We have mapped 11 compact high-velocity clouds (CHVCs) in the 21-cm line
emission of neutral, atomic hydrogen, using the Effelsberg 100-m radio
telescope. The aim of our observations was to study the overall distribution of
the warm neutral medium of CHVCs with high sensitivity. The achieved baseline
rms of about 50 mK at the original 2.6 km/s velocity resolution allows us to
search for evidence of ram-pressure interaction with the ambient medium. In
addition, we have obtained spectra along an appropriate axis across each CHVC
with longer integration times and denser angular sampling. These deep slices
with a spectral baseline rms of about 25...35 mK allow us to determine the
column density profile in greater detail as well as the velocity and line width
gradient across each cloud. The most outstanding result of our observations is
the complexity of the HI column density distribution and the line profiles of
the investigated CHVCs. We have found only one cloud with a
spherically-symmetric appearance. Among the remaining clouds we observe
head-tail structures, bow-shock shapes, and objects with irregular shapes.
These complex morphologies in combination with the obtained physical parameters
suggest that ram-pressure interactions with an ambient medium may play a
significant role in shaping some of the CHVCs from our sample. These results
are consistent with a circumgalactic distribution of CHVCs with typical
distances of the order of 100 kpc. The pressure of the ambient medium might
also stabilise CHVCs in addition to their own gravitational potential.


title: Comments on "Bigger Rip with no dark energy"

abstract:
  We make corrections on the paper by Frampton and Takahashi [{\it Astropart.
Phys.} {\bf 22} (2004) 307]. Our focus is especially upon Eqs. (12-15) therein.


title: The Spectral Variability of Pulsating Stars: PG1159-035

abstract:
  With 10m class telescopes as well as with time-tagging detectors on board of
HST and FUSE, the analysis of time-resolved spectra for pulsating white dwarfs
becomes feasible. We present simulated time-resolved spectra for the hot
pulsating white dwarf PG1159-035 and compare these models with observational
data of the 516s mode based on HST-STIS spectroscopy. A determination of the
pulsation mode by the spectral variability of PG1159-035 seems to be impossible
for the moment.


title: Solar-like oscillations in the F9 V beta Virginis

abstract:
  This paper presents the analysis of Doppler p-modes of the F9 V star beta
Virginis obtained with the spectrograph CORALIE in March 2003. Eleven nights of
observations have made it possible to collect 1293 radial velocity measurements
with a standard deviation of about 2.2 m s^-1. The power spectrum of the high
precision velocity time series clearly presents several identifiable peaks
between 0.7 and 2.4 mHz showing regularity with a large and small spacings of
Delta_nu = 72.1 uHz and delta_nu_02 = 6.3 uHz respectively. Thirty-one
individual modes have been identified with amplitudes in the range 23 to 46 cm
s^-1, i.e. with a signal to noise between 3 and 6.


title:
Discovery of new Milky Way star cluster candidates in the 2MASS Point
  Source Catalog IV. Follow-up observations of cluster candidates in the
  Galactic plane

abstract:
  Nearly 500 cluster candidates have been reported by searches based on the new
all-sky near infrared surveys. The true nature of the majority of these objects
is still unknown. This project aims to estimate the physical parameters of some
of the candidates in order to use them as probes of the obscured star formation
in the Milky Way.
  Here we report deep near infrared observations of four objects, discovered by
our search based on the 2MASS Point Source Catalog (Ivanov et al. 2002;
Borissova et al. 2003). CC04 appears to be a few million year old cluster. We
estimate its distance and extinction, and set a limit on the total mass. CC08
contains red supergiants, indicating a slightly older age of about 7-10 Myr.
The suspected cluster nature of CC13 was not confirmed. CC14 appears to be an
interesting candidate with double-tail-like morphology but our data doesn't
allow us to derive a firm conclusion about the nature of this object.
  We found no supermassive star clusters similar to the Arches or the
Quintuplet (Mtot >= 10**4 Msolar) among the dozen confirmed clusters studied so
far in this series of papers, indicating that such objects are not common in
the Milky Way.


title: First VLBI mapping of circumstellar 29SiO maser emission

abstract:
  We report the first VLBI map of the v=0 J=1-0 maser line of 29SiO in the
long-period variable star IRC+10011. We have found that this maser emission is
composed of multiple spots distributed in an incomplete ring, suggesting that
this maser is also amplified tangentially, as already proposed in other SiO
circumstellar masers. We present also VLBI maps for the 7 mm 28SiO v=1 and 2
J=1-0 and the 3 mm v=1 J=2-1 lines. The 29SiO masing region appears to be
located in a layer in between the 28SiO v=1 J=1-0 and 28SiO v=1 J=2-1 lines. In
addition, we confirm that the 86 GHz maser v=1 J=2-1 forms in an outer region
of the circumstellar envelope compared to the other 28SiO masers studied.
Finally, we discuss the possible implications of the observational results on
the SiO maser pumping theory.


title:
Cosmic Rays Astrophysics and Neutrino Astronomy beyond and beneath the
  Horizons

abstract:
  Modern Terrestrial Cerenkov Telescopes and Array Scintillators facing the
Horizons may soon reveal far Cosmic Rays or nearer PeVs-EeVs Neutrino Showers
Astronomy. Indeed UHE neutrino interactions in air, leading to Horizontal
Showers, may take place through several channels: the main Glashow resonant
one, the charged nuclear interactions and the neutral current events. Analogous
events occur also for the neutrino-nucleon events.
  These interactions are producing hadronic or electromagnetic showers at the
far horizons and their correlated secondaries Cerenkov flashes. Comparable
interactions are producing, inside the Earth, the Horizontal, but Up-going
ultra-relativistic tau, whose decay in flight is source of tau Air Showers
(Uptaus and HorTaus); Horizontal Tau Air-Showers are rarely (one-two order of
magnitude) enhanced by highest mountain chains at horizons, as in AUGER
experimental site; their hadronic or electromagnetic traces are preferentially
at PeV-EeV energies; their tracks are amplified by their muon-gamma bundles
whose signals are above the random noises and better disentangled by Cerenkov
flashes in time coincidence. More exotic UHE SUSY interactions at tens PeVs-EeV
energy may blaze at Horizons. Anyway common High Energy Cosmic rays at
PeVs-EeVs energy must traces their presence in Magic-like Cerenkov Telescopes
at horizons. Present Magic Telescopes facing the Horizons are, at equal given
time, almost comparable with the Amanda underground neutrino detector.


title:
Full characterization of binary-lens event OGLE-2002-BLG-069 from PLANET
  observations

abstract:
  We analyze the photometric data obtained by PLANET and OGLE on the
caustic-crossing binary-lens microlensing event OGLE-2002-BLG-069. Thanks to
the excellent photometric and spectroscopic coverage of the event, we are able
to constrain the lens model up to the known ambiguity between close and wide
binary lenses. The detection of annual parallax in combination with
measurements of extended-source effects allows us to determine the mass,
distance and velocity of the lens components for the competing models. While
the model involving a close binary lens leads to a Bulge-Disc lens scenario
with a lens mass of M=(0.51 +- 0.15) M_sol and distance of D_L=(2.9 +- 0.4)
kpc, the wide binary lens solution requires a rather implausible binary
black-hole lens (M >=126 M_sol). Furthermore we compare current
state-of-the-art numerical and empirical models for the surface brightness
profile of the source, a G5III Bulge giant. We find that a linear
limb-darkening model for the atmosphere of the source star is consistent with
the data whereas a PHOENIX atmosphere model assuming LTE and with no free
parameter does not match our observations.


title:
Restoration of Brightness Distributions across Quasar's Accretion Disk
  from Observations of High Magnification Events in Components of Gravitational
  Lens QSO 2237+0305

abstract:
  We present a technique for the successive restoration of the branches of the
one-dimensional strip brightness distribution across a quasar's accretion disk
via the analysis of observations of high magnification events in measured
fluxes from the multiple quasar images produced by a gravitational lens.
Hypothesizing these events to by associated with microlensing by a fold
caustic, the branches of brightness distribution are searched for on compact
sets of non-negative, monotonically non-increasing, convex downward functions.
The results of numerical simulations show that the solution obtained is stable
against random noise. Analysis of the light curves of high magnification events
in the fluxes from components C and A of the gravitational lens QSO 2237+0305,
observed by the OGLE and GLITP groups, has yielded the forms of the strip
brightness distributions across the accretion disk of the lensed quasar. The
resulting sizes of the accretion disk are in agreement with results obtained
earlier via model-fitting. The form of the brightness distribution is
consistent with the expected appearance of an accretion disk rotating around
supermassive black hole.


title:
Using the EXIST Active Shields for Earth Occultation Observations of
  X-ray Sources

abstract:
  The EXIST active shields, planned for the main detectors of the coded
aperture telescope, will have approximately 15 times the area of the BATSE
detectors, and they will have a good geometry on the spacecraft for viewing
both the leading and trailing Earth's limb for occultation observations. These
occultation observations will complement the imaging observations of EXIST and
can extend them to higher energies. Earth occultation observations of the hard
X-ray sky with BATSE on the Compton Gamma Ray Observatory developed and
demonstrated the capabilities of large, flat, uncollimated detectors for
applying this observation method. With BATSE, a catalog of 179 X-ray sources
was monitored twice every spacecraft orbit for 9 years at energies above about
25 keV, resulting in 83 definite detections and 36 possible detections with 5
sigma detection sensitivities of 3.5-20 mcrab (20-430 keV) depending on the sky
location. This catalog included four transients discovered with this technique
and many variable objects (galactic and extragalactic.) This poster describes
the Earth occultation technique, summarizes the BATSE occultation observations,
and compares the basic observational parameters of the occultation detector
elements of BATSE and EXIST.


title:
The gravitational collapse of ONe electron-degenerate cores and white
  dwarfs: the role of $^{24}$Mg and $^{12}$C revisited

abstract:
  The final stages of the evolution of electron--degenerate ONe cores,
resulting from carbon burning in ``heavy weight'' intermediate--mass stars ($8
M_{\sun}\la M \la 11 M_{\sun}$) and growing in mass, either from carbon burning
in a shell or from accretion of matter in a close binary system, are examined
in the light of their detailed chemical composition. In particular, we have
modelled the evolution taking into account the abundances of the following
minor nuclear species, which result from the previous evolutionary history:
$^{12}$C, $^{23}$Na, $^{24}$Mg, and $^{25}$Mg. Both $^{23}$Na and $^{25}$Mg
give rise to Urca processes, which are found to be unimportant for the final
outcome of the evolution. $^{24}$Mg was formerly considered a major component
of ONe cores (hence called ONeMg cores), but updated evolutionary calculations
in this mass range have severely reduced its abundance. Nevertheless, we have
parameterized it and we have found that the minimum amount of $^{24}$Mg
required to produce NeO burning at moderate densities is $\sim 23%$, a value
exceedingly high in the light of recent evolutionary models. Finally, we have
determined that models with relatively small abundances of unburnt carbon
($X(^{12}$C)$\sim 0.015$) could be a channel to explosion at low to moderate
density ($\sim 1\times 10^9$ g cm$^{-3}$). This is clearly below the current
estimate for the explosion/collapse threshold and would have interesting
consequences.


title: Local Starbursts in a Cosmological Context

abstract:
  In this contribution I introduce some of the major issues that motivate the
conference, with an emphasis on how starbursts fit into the ``big picture''. I
begin by defining starbursts in several different ways, and discuss the merits
and limitations of these definitions. I will argue that the most physically
useful definition of a starburst is its ``intensity'' (star formation rate per
unit area). This is the most natural parameter to compare local starbursts with
physically similar galaxies at high redshift, and indeed I will argue that
local starbursts are unique laboratories to study the processes at work in the
early universe. I will describe how NASA's GALEX mission has uncovered a rare
population of close analogs to Lyman Break Galaxies in the local universe. I
will then compare local starbursts to the Lyman-Break and sub-mm galaxies high
redshift populations, and speculate that the multidimensional ``manifold'' of
starbursts near and far can be understood largely in terms of the
Schmidt/Kennicutt law and galaxy mass-metallicity relation. I will briefly
summarize he properties of starburst-driven galactic superwinds and their
possible implications for the evolution of galaxies and the IGM. These complex
multiphase flows are best studied in nearby starbursts, where we can study the
the hot X-ray gas that contains the bulk of the energy and newly produced
metals.


title:
Measuring Accretion in Young Substellar Objects: Approaching the
  Planetary Mass Regime

abstract:
  We present observations of Halpha emission line profiles taken at Magellan
Observatory for a sample of 39 young low-mass stars and brown dwarfs in the
Taurus and Chamaeleon I star forming regions. We have identified 11 new
substellar accretors, more than tripling the number of known brown dwarfs with
measurable accretion activity. These include the lowest-mass objects yet seen
with accretion, with masses down to ~0.015 Msun. Using models of Halpha
emission produced in magnetospheric accretion flows, the most widely applicable
primary calibrator now available, we determine the first estimates of mass
accretion rates for objects at such extremely low masses. For the six objects
with masses < 0.03 Msun, we find accretion rates of ~ 5x10^{-12} Msun/yr, among
the smallest yet measured. These new results continue the trend of decreasing
mass accretion rate with decreasing (sub)stellar mass that we have noted
previously for samples of more massive objects; the overall correlation is Mdot
\~ M^{2.1}, and now extends over a mass range of over two orders of magnitude.
Finally, the absence of a discontinuity in the distribution of accretion rates
with mass tends to suggest that stars and brown dwarfs share similar formation
histories.


title: Density and Temperature Structure of TMC-1C from 450 and 850 micron Maps

abstract:
  We have mapped the central 10'x10' of the dense core TMC-1C at 450 and 850
microns using SCUBA on the James Clerk Maxwell Telescope. The unusually high
quality of the 450 micron map allows us to make a detailed analysis of the
temperature and column density profiles of the core. We find that the dust
temperature at the center of TMC-1C is 7 K, rising to 11 K at the edges. We
discuss the possibility and effects of a variable emissivity spectral index on
the derived mass profile. The low dust temperature of TMC-1C results in a high
derived mass for the core, significantly larger than the virial mass estimated
from the linewidth of the N2H+ (1-0) transition. This result is valid within a
wide range of dust properties and ellipticities of the core. The N2H+ (1-0)
spectra, taken with the IRAM 30m telescope, show signs of self-absorption,
which provide evidence of sub-sonic infall motions. The derived density profile
and infall velocity is compared to the predictions of several popular star
formation models, and the Bonnor-Ebert model isthe best fit analytic model.


title:
Discovery of new Milky Way star cluster candidates in the 2MASS point
  source catalog III. Follow-up observations of cluster candidates in the
  Galactic Center region

abstract:
  This paper is part of a project to search the inner Milky Way for hidden
massive clusters and to address the question of whether our Galaxy still forms
clusters similar to the progenitors of the present-day globular clusters.
  We report high angular resolution deep near-infrared imaging of 21 cluster
candidates selected from the catalogues of Bica et al. (2003) and Dutra et
al.(2003) in a region around the Galactic Center. These catalogues were created
from visual inspection of the 2MASS images. Seven objects appear to be genuine
clusters, and for these objects we present estimates of extinction, distance
and in some cases age and mass.
  Our estimated masses range from 1200 to 5500 solar masses. These clusters are
thus significantly smaller than any Galactic globular cluster, and indicate
that the formation of massive young clusters such as Arches and Quintuplet is
not common in the present-day Milky Way.
  The remaining 14 objects are either not clusters or cannot be classified
based on our data.


title:
Dynamics and Radiation of Young Type-Ia Supernova Remnants: Important
  Physical Processes

abstract:
  We examine and analyze the physical processes that should be taken into
account when modeling young type-Ia SNRs, with ages of several hundred years.
It is shown, that energy losses in the metal-rich ejecta can be essential for
remnants already at this stage of evolution. The influence of electron thermal
conduction and the rate of the energy exchange between electrons and ions on
the temperature distribution and the X-radiation from such remnants is studied.
The data for Tycho SNR from the XMM-Newton X-ray telescope have been employed
for the comparison of calculations with observations.


title:
The Broad-Band Spectrum and Infrared Variability of the Magnetar AXP
  1E1048.1-5937

abstract:
  We present photometry of the Anomalous X-ray pulsar 1E1048.1-5937 in the
infrared and optical, taken at Magellan and the VLT. The object is detected in
the I, J and Ks bands under excellent conditions. We find that the source has
varied greatly in its infrared brightness and present these new magnitudes. No
correlation is found between the infrared flux and spin-down rate, but the
infrared flux and X-ray flux may be anti-correlated. Assuming nominal reddening
values, the resultant spectral energy distribution is found to be inconsistent
with the only other AXP SED available (for 4U0142+61). We consider the effect
of the uncertainty in the reddening to the source on its SED. We find that
although both the X-ray and infrared fluxes have varied greatly for this
source, the most recent flux ratio is remarkably consistent with what is is
found for other AXPs. Finally, we discuss the implications of our findings in
the context of the magnetar model.


title:
Keck Spectroscopy of distant GOODS Spheroidal Galaxies: Downsizing in a
  Hierarchical Universe

abstract:
  We analyze the evolution of the Fundamental Plane for 141 field spheroidal
galaxies in the redshift range 0.2<z<1.2, selected morphologically to a
magnitude limit F850LP=22.43 in the northern field of the Great Observatories
Origin Survey. For massive galaxies we find that the bulk of the star formation
was completed prior to z=2. However, for the lower mass galaxies, the
luminosity-weighted ages are significantly younger. The differential change in
mass-to-light ratio correlates closely with rest-frame color, consistent with
recent star formation and associated growth. Our data are consistent with mass
rather than environment governing the overall growth, contrary to the
expectations of hierarchical assembly. We discuss how feedback, conduction, and
galaxy interactions may explain the downsizing trends seen within our large
sample.


title: Searching for Early Ionization with the Primeval Structure Telescope

abstract:
  The Primeval Structure Telescope (PaST), will be used search for and study
the era the of the first luminous objects, the epoch of reionization. The first
stars ionized the gas around them producing a pattern of ionization that
reflects the large scale density structure present at the time. The PaST array
will be used in an attempt to sense and study this ionization, by mapping the
brightness of 21-cm neutral hydrogen emission at redshifts from 6 to 25. This
emission disappears on ionization, allowing the study of large scale structure
and of star formation at this very early epoch. The 10,000 antenna PaST array
will be used to image ionized structures by creating 1 million pixel images of
the sky. The angular scales of the images to be produced span from 5
arc-minutes to 10 degrees. The array is currently under construction and over
2000 antennas have been installed.


title:
New radio observations of QSO 0957+561 confirm optical-to radio time
  delay

abstract:
  In our previous publications have been reported about possible time delay
between optical and radio (6 cm) variations in QSO 0957+561 and noted that the
result can be tested with new radio observations. Here we have made this test
using new published (Haarasma et al., 1999) radio observations of the object in
6 cm and 4 cm. We have found that the new observations confirm optical-to-radio
time delay. Additionally we have found that radio 6 cm variations followed 4 cm
ones with time delay about 230 days.
  Obtained results imply existence of the variable beamed hard radiation in the
nucleus of the QSO.


title: Energy Conditions and Segre Classification of Phantom Fields

abstract:
  Recent discoveries in the field of observational cosmology have provided
increasing evidence that the Universe is undergoing a late time acceleration,
which has also stimulated speculations on the nature of the dark component
responsible for such a phenomenon. Among several candidates discussed in the
current literature, phantom fields, an exotic scalar field with a negative
kinetic term and that violates most of the classical energy conditions, appear
as a real possibility according to recent observational analysis. In this paper
we examine the invariant characterization for the energy-momentum tensor of
phantom fields through the Segre algebraic classification in the framework of
general relativity. We also discuss some constraints which are imposed on the
values of $V(\phi)$ from the classical energy conditions.


title: Cosmological Surprises from Braneworld models of Dark Energy

abstract:
  Properties of Braneworld models of dark energy are reviewed. Braneworld
models admit the following interesting possibilities: (i) The effective
equation of state can be w < -1 as well as w > -1. In the former case the
expansion of the universe is well behaved at all times and the universe does
not run into a future `Big Rip' singularity which is usually encountered by
Phantom models. (ii) For a class of Braneworld models the acceleration of the
universe can be a transient phenomenon. In this case the current acceleration
of the universe is sandwiched between two matter dominated epochs. Such a
braneworld does not have a horizon in contrast to LCDM and most Quintessence
models. (iii) For a specific set of parameter values the universe can either
originate from, or end its existence in a Quiescent singularity, at which the
density, pressure and Hubble parameter remain finite, while the deceleration
parameter and all invariants of the Riemann tensor diverge to infinity within a
finite interval of cosmic time. (iv) Braneworld models of dark energy can
loiter at high redshifts: $6 \lleq z \lleq 40$. The Hubble parameter
decreasesduring the loitering epoch relative to its value in LCDM. As a result
the age of the universe at loitering dramatically increases and this is
expected to boost the formation of high redshift gravitationally bound systems
such as $10^9 M_\odot$ black holes at $z \sim 6$ and lower-mass black holes
and/or Population III stars at $z > 10$, whose existence could be problematic
within the LCDM scenario. (v) Braneworld models with a time-like extra
dimension bounce at early times thereby avoiding the initial `Big Bang
singularity'. (vi) Both Inflation and Dark Energy can be successfully unified
within a single scheme (Quintessential Inflation).


title: The Secular Decrease of the Crab Nebula at 927 and 151.5 MHz

abstract:
  Long-term measurements have been carried out of the Crab Nebula radio
emission flux density relative to Orion A at 927 MHz and relative to Cygnus A
and Virgo A at 151.5 MHz. As a result the mean rates have been found of the
secular change of the Crab Nebula radio emission flux density: $d_m
(927\hbox{MHz})=-(0.18\pm0.10)$% year$^{-1}$ (over the period 1977--2000), $d_m
(151.5\hbox{MHz})=- (0.32\pm0.08)$% year$^{-1}$ (over the period 1980--2003).


title: Cosmological model with energy transfer

abstract:
  The observations of SNIa suggest that we live in the acceleration epoch when
the densities of the cosmological constant term and matter are almost equal.
This leads to the cosmic coincidence conundrum. As the explanation for this
problem we propose the FRW model with dark matter and dark energy which
interact each other exchanging energy. We show that the cubic correction to the
Hubble law, measured by distant supernovae type Ia, probes this interaction. We
demonstrate that influences between nonrelativistic matter and vacuum sectors
are controlled by third and higher derivatives of the scale factor. As an
example we consider flat decaying $\Lambda(t)$ FRW cosmologies. We point out
the possibility of measure of the energy transfer by the cubic and higher
corrections to Hubble's law. The statistical analysis of SNIa data is used as
an evidence of energy transfer. We find that there were the transfer from the
dark energy sector to the dark matter one without any assumption about physics
governing this process. We confront this hypothesis about the transfer with
SNIa observations and find that the transfer the phantom and matter sector is
admissible for $\Omega_{\text{m},0}=0.27$. We also demonstrate that it is
possible to differentiate between the energy transfer model and the variable
coefficient equation of state model.


title:
Nuclear Accretion in Galaxies of the Local Universe: Clues from Chandra
  Observations

abstract:
  In order to find an explanation for the radiative quiescence of supermassive
black holes in the local Universe, for a sample of nearby galaxies the most
accurate estimates are collected for the mass of a central black hole M_BH, the
nuclear X-ray luminosity L_X,nuc and the circumnuclear hot gas density and
temperature, by using Chandra data. L_X,nuc varies by \sim 3 orders of
magnitude and does not show a relationship with M_BH or with the Bondi mass
accretion rate \dotM_B. L_X,nuc is always much lower than expected if \dotM_B
ends in a standard accretion disc with high radiative efficiency (this instead
can be the case of the active nucleus of Cen A). Radiatively inefficient
accretion as in the standard ADAF modeling may explain the low luminosities of
a few cases; for others, the predicted luminosity is still too high and, in
terms of Eddington-scaled quantities, it is increasingly higher than observed,
for increasing \dotM_B. Variants of the simple radiatively inefficient scenario
including outflow and convection may reproduce the low emission levels
observed, since the amount of matter actually accreted is reduced considerably.
However, the most promising scenario includes feedback from accretion on the
surrounding gas: this has the important advantages of naturally explaining the
observed lack of relationship between L_X,nuc, M_BH and \dotM_B, and of evading
the problem of the fate of the material accumulating in the central galactic
regions over cosmological times.


title:
GMRT Observations of the Group Holmberg 124: Evolution by Tidal Forces
  and Ram Pressure ?

abstract:
  We report radio continuum and 21cm HI observations using the Giant Metrewave
Radio Telescope of the group Ho124 comprising four late-type galaxies, NGC2820,
Mrk108, NGC2814 and NGC2805. Three of the galaxies have clearly undergone tidal
interactions as seen from the various morphological tidal signatures whereas
other features in the group members appear to be due to ram pressure. Here, we
describe four interesting results:(a) detection of the tidal radio continuum
bridge at 330 MHz connecting the galaxies NGC2820+Mrk108 with NGC2814 with a
spectral index of -1.8. The radio bridge was discovered by van der Hulst &
Hummel (1985) who reported a spectral index of -0.8.(b) Detection of various
tidal features including a possible tidal dwarf galaxy.(c) Sharp truncation in
the HI distribution in the south of NGC2820 and in the HI & radio continuum in
the north of NGC2814. The optical disks in both the cases look undisturbed. (d)
Detection of a large one-sided HI loop to the north of NGC 2820. No radio
continuum emission or Halpha emission is detected. We discuss various scenarios
for the origin of this loop. The central starburst scenario is not supported
due to lack of ionized gas in the loop. For an electron density of 4x10^(-4)
cm^-3 we estimate the ram pressure force of the IGrM to be comparable to the
gravitational pull of the disk of NGC2820. We suggest that the loop could have
formed by ram pressure stripping if tidal effects had reduced the surface
density of HI in NGC2820. Finally we suggest that the evolution of the Ho124
group may be governed by both tidal forces due to the interaction and ram
pressure due to motion of the member galaxies in the IGrM and that the IGrM
densities might not be too low (>~4x10^(-4)cm^-3). This should be verified by
other observations.


title: Modelling Kinematics and Dark Matter: The Halos of Elliptical Galaxies

abstract:
  This review is focussed on the outer halos of elliptical galaxies. Its
emphasis is on (i) planetary nebulae as test particles to trace the stellar
kinematics at large radii, (ii) the observed angular momentum in elliptical
galaxy halos and its theoretical relevance, (iii) dynamical modelling of
stellar-kinematic data, and (iv) a discussion of the evidence for dark matter
halos in ellipticals from a wide range of measurements.


title:
High-speed, energy-resolved, STJ observations of the AM Her system V2301
  Oph

abstract:
  We present high time-resolution optical energy-resolved photometry of the
eclipsing cataclysmic variable V2301 Oph made using the ESA S-Cam detector, an
array of photon counting super-conducting tunnel junction (STJ) devices with
intrinsic energy resolution. Three eclipses were observed, revealing
considerable variation in the eclipse shape, particularly during ingress. The
eclipse shape is shown to be understood in terms of AM Her accretion via a
bright stream, with very little contribution from the white dwarf photosphere
and/or hotspot. About two thirds of the eclipsed light arises in the threading
region. Variation in the extent of the threading region can account for most of
the variations observed between cycles. Spectral fits to the data reveal a
10,000K blackbody continuum with strong, time-varying emission lines of
hydrogen and helium. This is the first time that stellar emission lines have
been detected in the optical band using a non-dispersive photon-counting
system.


title:
A Northern Sky Survey for Steady TeV Gamma-Ray Point Sources Using the
  Tibet Air Shower Array

abstract:
  Results on steady TeV $\gamma$-ray point source search using data taken from
the Tibet HD (Feb. 1997 -- Sep. 1999) and Tibet III (Nov. 1999 -- Oct. 2001)
arrays are presented. From $0^{\circ}$ to $60^{\circ}$ in declination,
significant excesses from the well-known steady source Crab Nebula and the high
state of the flare type source Markarian 421 are observed. Because the levels
of significance from other positions are not sufficiently high, 90% confidence
level upper limits on the flux are set assuming different power law spectra. To
allow crosschecking, two independently developed analyses are used in this
work.


title:
GALEX UV observations of the interacting galaxy NGC 4438 in the Virgo
  cluster

abstract:
  We present GALEX NUV (2310 A) and FUV (1530 A) images of the interacting
galaxy NGC 4438 (Arp 120) in the center of the Virgo cluster. These images show
an extended (20 kpc) tidal tail at the north-west edge of the galaxy previously
undetected at other wavelengths, at 15-25 kpc from its nucleus. Except in the
nucleus, the UV morphology of NGC 4438 is totally different from the
Halpha+[NII] one, more similar to the X-ray emission, confirming its gas
cooling origin. We study the star formation history of NGC 4438 combining
spectro-photometric data in the UV-visible-near-IR wavelength range with
population synthesis and galaxy evolution models. The data are consistent with
a recent (~ 10 Myr), instantaneous burst of star formation in the newly
discovered UV north-western tail which is significantly younger than the age of
the tidal interaction with NGC 4435, dated by dynamical models at ~ 100 Myr
ago. Recent star formation events are also present at the edge of the northern
arm and in the southern tail, while totally lacking in the other regions, which
are dominated by the old stellar population perturbed during the dynamical
interaction with NGC 4435. The contribution of this recent starburst to the
total galaxy stellar mass is lower than 0.1%, an extremely low value for such a
violent interaction. High-velocity, off-center tidal encounters such as that
observed in Arp 120 are thus not sufficient to significantly increase the star
formation activity of cluster galaxies.


title: The GALEX UV luminosity function of the cluster of galaxies Abell 1367

abstract:
  We present the GALEX NUV (2310 A) and FUV (1530 A) galaxy luminosity
functions of the nearby cluster of galaxies A1367 in the magnitude range -20.3<
M_AB < -13.3. The luminosity functions are consistent with previous (~ 2 mag
shallower) estimates based on the FOCA and FAUST experiments, but display a
steeper faint-end slope than the GALEX luminosity function for local field
galaxies. Using spectro-photometric optical data we select out star-forming
systems from quiescent galaxies and study their separate contributions to the
cluster luminosity function. We find that the UV luminosity function of cluster
star-forming galaxies is consistent with the field. The difference between the
cluster and field LF is entirely due to the contribution at low luminosities
(M_AB >-16 mag) of non star-forming, early-type galaxies that are significantly
over dense in clusters.


title: Pulsating young brown dwarfs

abstract:
  We present the results of a nonadiabatic, linear stability analysis of models
of very low-mass stars (VLMSs) and brown dwarfs (BDs) during the deuterium
burning phase in the center. We find unstable fundamental modes with periods
varying between ~5 hr for a 0.1 Msun star and ~1 hr for a 0.02 Msun BD. The
growth time of the instability decreases with decreasing mass and remains well
below the deuterium burning time scale in the mass range considered (0.1--0.02
Msun). These results are robust against variations of the relevant input
physics in the evolutionary models. We identify possible candidates for
pulsational variability among known VLMSs and BDs in nearby star forming
regions whose location in the HR diagram falls within or close to the boundary
of the instability strip. Finally, we discuss the possibility that the
variability observed in a few objects with periods of ~1 hr can be interpreted
in terms of pulsation.


title: A fossil origin for the magnetic fields of A-stars and white dwarfs

abstract:
  Some main-sequence stars of spectral type A are observed to have a strong
(300-30000 G), static, large-scale magnetic field, of a chiefly dipolar shape
-- the `Ap stars' (for example Alioth, the fifth star in the Big Dipper).
Following their discovery fifty years ago, it was speculated that these fields
a remnants of the star's formation, a `fossil' field. Alternatively, they could
be generated by a dynamo process in the star's convective core. The dynamo
hypothesis has difficulty explaining high field strengths and the lack of a
correlation with rotation. The weakness of the fossil-field theory has been the
absence of known field configurations stable enough to survive in a star over
its lifetime. We demonstrate here the formation of stable magnetic field
configurations, with properties agreeing with those observed, by evolution from
arbitrary, unstable initial fields. The results are applicable equally to Ap
stars, magnetic white dwarfs and some highly magnetised neutron stars known as
magnetars. This establishes fossil fields as the natural, unifying explanation
for the magnetism of all these stars.


title:
Accretion of cool stellar winds on Sgr A*: another puzzle of the
  Galactic Centre?

abstract:
  Sgr A* is currently being fed by winds from a cluster of gravitationally
bound young mass-loosing stars. Using observational constraints on the orbits,
mass loss rates and wind velocities of these stars, we numerically model the
distribution of gas in the ~ 0.1--10'' region around Sgr A*. We find that
radiative cooling of recently discovered slow winds leads to the formation of
many cool filaments and blobs, and to a thin and rather light accretion disc of
about an arcsecond scale. The disc however does not extend all the way to our
inner boundary. Instead, hot X-ray emitting gas dominates the inner arcsecond.
In our simulations, cool streams of gas frequently enter this region on low
angular momentum orbits, and are then disrupted and heated up to the ambient
hot gas temperature. The accreting gas around Sgr A* is thus two-phase, with a
hot component, observable at X-ray wavelengths, and a cool component, which may
be responsible for the majority of time variability of Sgr A* emission on
hundred and thousand years time-scales. We obtain an accretion rate of a few
times 10^-6 msun/year, consistent with Chandra estimates, but variable on
time-scales even shorter than hundred years. These results strongly depend on
the chosen stellar orbits and wind parameters. Further observational input is
thus key to a better modelling of Sgr A* wind accretion.