title:
Cosmological density fluctuations and gravity waves: A covariant
  approach to gauge-invariant non-linear perturbation theory

abstract:
  We present a new approach to gauge-invariant cosmological perturbations at
second order, which is also covariant. We examine two cases in particular for a
dust Friedman-Lemaitre-Robertson-Walker model of any curvature: we investigate
gravity waves generated from clustering matter, that is, induced tensor modes
from scalar modes; and we discuss the generation of density fluctuations
induced by gravity waves -- scalar modes from tensor perturbations. We derive a
linear system of evolution equations for second-order gauge-invariant variables
which characterise fully the induced modes of interest, with a source formed
from variables quadratic in first-order quantities; these we transform into
fully-fledged second-order gauge-invariant variables. Both the invariantly
defined variables and the key evolution equations are considerably simpler than
similar gauge-invariant results derived by other methods. By finding analytical
solutions, we demonstrate that non-linear effects can significantly amplify or
dampen modes present in standard linearised cosmological perturbation theory,
thereby providing an important source of potential error in, and refinement of,
the standard model. Moreover, these effects can dominate at late times, and on
super-Hubble scales.


title: Methods for the Pointing Reconstruction of the Planck satellite

abstract:
  This paper presents a method to reconstruct the position of the line of sight
and orientation of the focal plane of the Planck satellite, which may be
expressed by the parameters of the effective boresight and roll angles,
respectively. The accuracy to which these parameters must be determined to
avoid compromising the reconstruction of the C_{\ell} power spectrum is
assessed. It is expected that the pointing reconstruction will be performed
using point source transits in the highest frequency channels, given their
smaller beam sizes. Estimates are made for the number of galactic and
extragalactic point sources visible by Planck in these channels. The ability of
the method presented here to reconstruct the pointing parameters to the
required accuracies using these point sources is investigated. It is found that
the scanning strategy employed and the actual orientation of the focal plane
both independently influence the available number of suitable point sources,
from which this method may successfully evaluate the pointing parameters. While
this paper focuses on the pointing reconstruction of the Planck satellite,
elements of the analysis presented here may be of use elsewhere.


title: Early Enrichment of Quasars by First Stars

abstract:
  Studies of the broad emission-line regions (BLRs) in quasars have revealed
solar or higher enrichment levels up to the highest redshifts. In combination
with the presence of large amounts of dust in QSOs at $z$ about 6, this implies
that substantial amounts of star formation and nucleosynthesis took place at
significantly earlier epochs. Here, we examine whether a top-heavy stellar
initial mass function (IMF) is indicated by current data, by modelling the
contributions from different regions of the IMF, including Type Ia/II and pair
instability supernovae, to the metal synthesis in BLRs. We find that, in order
to reproduce the observations of roughly solar values of N/C and Fe/Mg in these
objects, (i) stars with a present-day IMF are sufficient, regardless of their
metallicity, (ii) zero-metallicity stars with a top-heavy IMF severely
underproduce N/C, and (iii) the contribution of Type Ia SNe is not strongly
required by the data. Therefore, stars of mass about 1-40 $M_\odot$ must have
existed at $z$ about 10-20, possibly coeval with any hypothesized stars of
masses exceeding about 100 $M_\odot$ at these epochs. This is in agreement with
the nucleosynthetic abundance pattern detected in extremely metal-poor stars in
the galactic halo.


title:
Reconstructing images of gravitational lenses with regularizing
  algorithms

abstract:
  This note addresses possible applications of the Tikhonov regularization to
image reconstruction of gravitational lens systems. Several modifications of
the regularization algorithm are discussed. Our illustrative example is the
close quadruple gravitational lens QSO 2237+0305 (Einstein Cross). The restored
image of the lens is decomposed into two parts - the quasar components and the
background galaxy.


title:
The "Supercritical Pile" Model of GRB: Thresholds, Polarization, Time
  Lags

abstract:
  The essence of the ``Supercritical Pile'' model is a process for converting
the energy stored in the relativistic protons of a Relativistic Blast Wave
(RBW) of Lorentz factor $\Gamma$ into electron -- positron pairs of similar
Lorentz factor, while at the same time emitting most of the GRB luminosity at
an energy $E_p \simeq 1$ MeV. This is achieved by scattering the synchrotron
radiation emitted by the RBW in an upstream located ``mirror'' and then
re-intercepting it by the RBW. The repeated scatterings of radiation between
the RBW and the ``mirror'', along with the threshold of the pair production
reaction $p \gamma \to p e^-e^+$, lead to a maximum in the GRB luminosity at an
energy $E_p \simeq 1$ MeV, {\sl independent of the value of $\Gamma$}.
Furthermore, the same threshold implies that the prompt $\gamma-$ray emission
is only possible for $\Gamma$ larger than a minimum value, thereby providing a
``natural'' account for the termination of this stage of the GRB as the RBW
slows down. Within this model the $\gamma-$ray ($E \sim 100$ keV -- 1 MeV)
emission process is due to Inverse Compton scattering and it is thus expected
to be highly polarized if viewed at angles $\theta \simeq 1/\Gamma$ to the
RBW's direction of motion. Finally, the model also predicts lags in the light
curves of the lower energy photons with respect to those of higher energy;
these are of purely kinematic origin and of magnitude $\Delta t \simeq 10^{-2}$
s, in agreement with observation.


title:
The Chemical Composition Contrast between M3 and M13 Revisited: New
  Abundances for 28 Giant Stars in M3

abstract:
  We report new chemical abundances of 23 bright red giants of the globular
cluster M3, based on high-resolution spectra obtained with the Keck I
telescope. Combining these data with a previously-reported small sample of M3
giants obtained with the Lick 3m telescope, we compare [X/Fe] ratios for 28 M3
giants with 35 M13 giants, and with halo field stars. All three groups exhibit
C depletion with advancing evolutionary state beginning at the RGB bump region.
but the overall depletion in the clusters is larger than that of the field
stars. The behaviors of O, Na, Mg and Al are distinctively different among the
three stellar samples. Both M3 and M13 show evidence of high-temperature proton
capture synthesis from the ON, NeNa, and MgAl cycles, while there is no
evidence for such synthesis among halo field stars. But the degree of such
extreme proton-capture synthesis in M3 is smaller than it is in M13, and no
indication that O depletions are a function of advancing evolutionary state as
has been claimed for M13. We have also considered NGC 6752, for which Mg
isotopic abundances have been reported by Yong et al. (2003). Giants in NGC
6752 and M13 satisfy the same anticorrelation of O abundances with the ratio
(25Mg+26Mg)/24Mg. This suggests that these abundance ratios arose in the
ejected material of 3-6 solar mass cluster stars. It also suggests that the low
oxygen abundance seen among the most evolved M13 giants arose in hot-bottom O
to N processing in these same intermediate-mass cluster stars. Thus mixing is
required by the dependence of some abundance ratios on luminosity, but an
earlier nucleosynthesis process in a hotter environment than giants or
main-sequence stars is required by the variations previously seen in stars near
the main sequence.


title: The Cluster Galaxy Circular Velocity Function

abstract:
  We present galaxy circular velocity functions (GCVFs) for 34 low redshift (z
< 0.15) clusters identified in the Sloan Digital Sky Survey (SDSS), for fifteen
clusters drawn from dark matter simulations of hierarchical structure growth in
a LambdaCDM cosmology, and for ~29,000 SDSS field galaxies. We find that the
observed and simulated cluster GCVFs take the form of a power law. The
cumulative GCVFs of the simulated clusters are very similar across a wide range
of cluster masses, provided individual subhalo circular velocities are scaled
by the circular velocities of the parent cluster. Once all sources of error are
accounted for, the intrinsic scatter in the cumulative, scaled observed cluster
GCVF is consistent with the simulations. The slope of the observed cluster GCVF
is -2.5, independent of cluster velocity dispersion. The average slope of the
simulated GCVFs is somewhat steeper, although formally consistent given the
errors. Using our highest resolution cluster, we find that the effects of
baryons on galaxy rotation curves is to flatten the simulated cluster GCVF into
better agreement with observations. Finally, we find that the field GCVF
deviates significantly from a power law, being flatter than the cluster GCVF at
circular velocities less than 200 km/s, and steeper at circular velocities
greater than 200 km/s.


title:
Direct Feeding of the Black Hole at the Galactic Center with Radial Gas
  Streams from Close-In Stellar Winds

abstract:
  We show that the recently-discovered orbits of massive stars with closest
approach of ~10^3 Schwarzschild radii from SgrA*, allow winds from these stars
to provide the required mass deposition rate near the black hole horizon. The
observed luminosity of SgrA* does not require viscous transport of angular
momentum, as long as the total wind mass loss rate reaches ~10^{-6} solar
masses per year from the close-in stars. The specific orbits of the nearest
stars should cause modulation of the radio and infrared flux from SgrA* on a
timescale of years in a predictable fashion.


title: Cross-Correlation Studies with CMB Polarization Maps

abstract:
  The free-electron population during the reionized epoch rescatters CMB
temperature quadrupole and generates a now well-known polarization signal at
large angular scales. While this contribution has been detected in the
temperature-polarization cross power spectrum measured with WMAP data, due to
the large cosmic variance associated with anisotropy measurements at tens of
degree angular scales only limited information related to reionization, such as
the optical depth to electron scattering, can be extracted. The inhomogeneities
in the free-electron population lead to an additional secondary polarization
anisotropy contribution at arcminute scales. While the fluctuation amplitude,
relative to dominant primordial fluctuations, is small, we suggest that a
cross-correlation between arcminute scale CMB polarization data and a tracer
field of the high redshift universe, such as through fluctuations captured by
the 21 cm neutral Hydrogen background or those in the infrared background
related to first proto-galaxies, may allow one to study additional details
related to reionization. For this purpose, we discuss an optimized higher order
correlation measurement, in the form of a three-point function, including
information from large angular scale CMB temperature anisotropies in addition
to arcminute scale polarization signal related to inhomogeneous reionization.
We suggest that the proposed bispectrum can be measured with a substantial
signal-to-noise ratio and does not require all-sky maps of CMB polarization or
that of the tracer field. A measurement such as the one proposed may allow one
to establish the epoch when CMB polarization related to reionization is
generated and to address if the universe was reionized once or twice.


title: 21 Centimeter Fluctuations from Cosmic Gas at High Redshifts

abstract:
  The relatively large Thomson optical depth, tau_e, inferred recently from the
WMAP observations suggests that the Universe was reionized in a more complex
manner than previously believed. However, the value of tau_e provides only an
integral constraint on the history of reionization and, by itself, cannot be
used to determine the nature of the sources responsible for this transition.
Here, we show that the evolution of the ionization state of the intergalactic
medium at high redshifts can be measured statistically using fluctuations in 21
centimeter radiation from neutral hydrogen. By analogy with the mathematical
description of anisotropies in the cosmic microwave background, we develop a
formalism to quantify the variations in 21 cm emission as a function of both
frequency and angular scale. Prior to and following reionization, fluctuations
in the 21 cm signal are mediated by density perturbations in the distribution
of matter. Between these epochs, pockets of gas surrounding luminous objects
become ionized, producing large HII regions. These ``bubbles'' of ionized
material imprint features into the 21 cm power spectrum that make it possible
to distinguish them from fluctuations produced by the density perturbations.
The variation of the power spectrum with frequency can be used to infer the
evolution of this process. As has been emphasized previously by others, the
absolute 21 cm signal from neutral gas at high redshifts is undetectable owing
to contamination by foreground sources. However, we argue that this source of
noise can be suppressed by comparing maps closely spaced in frequency, i.e.
redshift, so that 21 cm fluctuations from the IGM can be measured against a
much brighter, but smoothly varying (in frequency) background.


title: Non-linear Galaxy Power Spectrum and Cosmological Parameters

abstract:
  The galaxy power spectrum is now a well-known tool of precision cosmology. In
addition to the overall shape, baryon oscillations and the small-scale
suppression of power by massive neutrinos capture complimentary information on
cosmological parameters when compared to the angular power spectrum of cosmic
microwave background anisotropies. We study both the real space and redshift
space galaxy power spectra in the context of non-linear effects and model them
based on the halo approach to large scale structure clustering. We consider
potential systematic in the cosmological parameter determination when
non-linear effects are ignored and the galaxy power spectrum is described with
the linear power spectrum scaled by a constant bias factor. We suggest that
significant improvements can be made when non-linear effects are taken into
account as a power-law contribution with two additional parameters to be
determined from the data. In addition to cosmological parameters through galaxy
clustering, such an approach allow a determination of useful information
related to astrophysics on how galaxies occupy dark matter halos.


title: Effects of Fluid Instabilities on Accretion Disk Spectra

abstract:
  Numerical calculations and linear theory of radiation magnetohydrodynamic
flows indicate that the photon bubble and magnetorotational instability (MRI)
may produce large density inhomogeneities in radiation pressure supported
media. We study the effects of the photon bubble instability on accretion disk
spectra using 2-D Monte Carlo (MC) and 1-D Feautrier radiative transfer
calculations on a snapshot of a 2-D numerical simulation domain. We find an
enhancement in the thermalization of the MC spectra over that of the Feautrier
calculation. In the inner-most regions of these disks, the turbulent magnetic
pressure may greatly exceed that of the gas. It is then possible for bulk
turbulent Alfvenic motions driven by the MRI to exceed the thermal velocity
making turbulent Comptonization the dominant radiative process. We estimate the
spectral distortion due to turbulent Comptonization utilizing a 1-D MC
calculation.


title:
Cryogenic Tests of Volume-Phase Holographic Gratings: I. Results at 200
  K

abstract:
  We present results from cryogenic tests of a Volume-Phase Holographic (VPH)
grating at 200 K measured at near-infrared wavelengths. The aims of these tests
were to see whether the diffraction efficiency and angular dispersion of a VPH
grating are significantly different at a low temperature from those at a room
temperature, and to see how many cooling and heating cycles the grating can
withstand. We have completed 5 cycles between room temperature and 200 K, and
find that the performance is nearly independent of temperature, at least over
the temperature range which we are investigating. In future, we will not only
try more cycles between these temperatures but also perform measurements at a
much lower temperature (e.g., 80 K).


title: Simulations of the Intergalactic Medium

abstract:
  I present a review by epoch of baryons in the intergalactic medium (IGM),
from the first star until today. Recent observations indicate a protracted
period of reionization, suggesting multiple populations of reionizers;
detection of these z>6 sources is a key goal that is now coming within reach.
The optical Lyman alpha forest (2<z<4) is well-described by the Fluctuating
Gunn-Peterson Approximation, but puzzling observations of associated metal
lines and nearby galaxies may provide insights into galactic feedback
processes. IGM studies at z<1.5 are progressing rapidly thanks to ultraviolet
absorption line studies of both Ly-alpha absorbers and the warm-hot
intergalactic medium. Cosmological hydrodynamic simulations have played an
integral part in these advances, and have helped to shape our understanding of
the IGM at each epoch. Working jointly, observations and theory continue to
expand our knowledge of the IGM as the earliest stages of galaxy formation and
the dominant reservoir of baryons at all redshifts.


title:
Astrometric Microlensing of Quasars : Dependence on surface mass density
  and external shear

abstract:
  A small fraction of all quasars are strongly lensed and multiply imaged, with
usually a galaxy acting as the main lens. Some, maybe all of these quasars are
also affected by microlensing, the effects of stellar mass objects in the
lensing galaxy. Stellar microlensing not only has photometric effects
(magnitude fluctuations of the quasar images), it also affects the observed
position of the images. This astrometric effect was first explored by Lewis and
Ibata (1998): the position of the quasar - i.e. the center-of-light of the many
microimages - can shift by tens of microarcseconds due to the relatively sudden
(dis-)appearance of a pair of microimages when a caustic is being crossed.
  We explore this effect quantitatively for different values of the surface
mass density and external shear covering most of the known multiple quasar
systems. We show examples of microlens-induced quasar motion and the
corresponding light curves for different quasar sizes. We evaluate
statistically the occurrence of large shifts in angular position and their
correlation with apparent brightness fluctuations. We also show statistical
relations between positional offsets and time from random starting points.
  As the amplitude of the astrometric offset depends on the source size,
astrometric microlensing signatures of quasars - combined with the photometric
variations - will provide very good constraints on the size of quasars as a
function of wavelength. We predict that such signatures will be detectable for
realistic microlensing scenarios with near future technology in the
infrared/optical (Keck-Interferometry, VLTI, SIM, GAIA). Such detections will
show that not even high redshift quasars define a 'fixed' coordinate system.


title: Implications of IR continua for x-ray emission/reflection in AGN

abstract:
  Observations of infrared emission from AGN show that grains exist over a
broad range of distances from the central object, extending to the point where
they are destroyed by sublimation. These ~1000 K grains produce much of the 1
micron continuum. In this region closest to the central object there must be a
gaseous component associated with the hot grains. This paper employs a state of
the art grain model and shows that the gas must be very hot, with temperatures
in the neighborhood of 10^6 K. The dusty component has a covering factor of
roughly 50% and so this region also reprocesses much of the total x-ray
emission. Our explicit models of the IR through x-ray spectral energy
distributions allow the x-ray component to be predicted from IR observations.
We are creating a grid of such predictions and will make them available as an
XSPEC add-in, allowing this spectral component to be included in quantitative
modeling of AGN spectra.


title:
On the evolutionary states of neutron stars in pre-low-mass X-ray
  binaries

abstract:
  We present a simple model for the evolutionary states of neutron stars in
pre-low-mass X-ray binaries during the main sequence stage of donor stars. It
is shown that for typical parameters some of the neutron stars in these systems
can not accrete matter from winds of their companions in a stable way.
Accretors are found if neutron stars have magnetic fields about $10^{13}$ G and
higher and/or in close systems with orbital periods about a few days and
shorter.


title: Dark Matter Constraints from the Sagittarius Dwarf and Tail System

abstract:
  2MASS has provided a three-dimensional map of the >360 degree, wrapped tidal
tails of the Sagittarius (Sgr) dwarf spheroidal galaxy, as traced by M giant
stars. With the inclusion of radial velocity data for stars along these tails,
strong constraints exist for dynamical models of the Milky Way-Sgr interaction.
N-body simulations of Sgr disruption with model parameters spanning a range of
initial conditions (e.g., Sgr mass and orbit, Galactic rotation curve, halo
flattening) are used to find parameterizations that match almost every extant
observational constraint of the Sgr system. We discuss the implications of the
Sgr data and models for the orbit, mass and M/L of the Sgr bound core as well
as the strength, flattening, and lumpiness of the Milky Way potential.


title: Where Are Be/black-hole Binaries?

abstract:
  We apply the tidal truncation model proposed by Negueruela & Okazaki(2001) to
arbitrary Be/compact star binaries to study the truncation efficiency
dependance on the binary parameters. We find that the viscous decretion disks
around the Be stars could be truncated very effectively in narrow systems.
Combining this with the population synthesis results of Podsiadlowski,
Rappaport and Han (2003) that binary black holes are most likely to be born in
systems with orbital periods less than about 30 days, we suggest that most of
the Be/black-hole binaries may be transient systems with very long quiescent
states. This could explain the lack of observed Be/black-hole X-ray binaries.
We also discuss the evolution of the Be/black-hole binaries and their possible
observational features.


title:
Enhanced production of HD and D_2 molecules on small dust grains in
  diffuse clouds

abstract:
  Motivated by recent observations of deuterated molecules in the interstellar
medium, we examine the production of HD and D$_2$ molecules on dust grain
surfaces. A mechanism for the enhanced production of these deuterated molecules
is studied. This mechanism applies on grain surfaces on which D atoms stick
more strongly than H atoms, under conditions of low flux and within a suitable
range of temperatures. It is shown that under these conditions the production
rates of HD and D$_2$ are greatly enhanced (vs. the H$_2$ production rate)
compared with the expected rates based on the adsorption of gas-phase atomic
abundances of D and H. The enhancement in the formation rate of HD is
comparable with the enhancement due to gas-phase ion-molecule reactions in
diffuse clouds.


title:
Cepheid distances from infrared long-baseline interferometry - I.
  VINCI/VLTI observations of seven Galactic Cepheids

abstract:
  We report the angular diameter measurements of seven classical Cepheids (X
Sgr, eta Aql, W Sgr, zeta Gem, beta Dor, Y Oph and L Car) that we have obtained
with the VINCI instrument, installed at ESO's VLT Interferometer (VLTI). We
also present reprocessed archive data obtained with the FLUOR/IOTA instrument
on zeta Gem, in order to improve the phase coverage of our observations. We
obtain average limb darkened angular diameter values of LD(X Sgr) = 1.471 +/-
0.033 mas, LD(eta Aql) = 1.839 +/- 0.028 mas, LD(W Sgr) = 1.312 +/- 0.029 mas,
LD(beta Dor) = 1.891 +/- 0.024 mas, LD(zeta Gem) =1.747 +/- 0.061 mas, LD(Y
Oph) = 1.437 +/- 0.040 mas and LD(L Car) = 2.988 +/- 0.012 mas. For four of
these stars (eta Aql, W Sgr, beta Dor, and L Car) we detect the pulsational
variation of their angular diameter. This enables us to compute directly their
distances, using a modified version of the Baade-Wesselink method: d(eta Aql) =
276 [+55 -38] pc, d(W Sgr) = 379 [+216 -130] pc, d(beta Dor) = 345 [+175 -80]
pc, d(L Car) = 603 [+24 -19] pc. The stated error bars are statistical in
nature. Applying a hybrid method, that makes use of the Gieren et al. (1998)
Period-Radius relation to estimate the linear diameters, we obtain the
following distances (statistical and systematic error bars are mentioned): d(X
Sgr) = 324 +/- 7 +/- 17 pc, d(eta Aql) = 264 +/- 4 +/- 14 pc, d(W Sgr) = 386
+/- 9 +/- 21 pc, d(beta Dor) = 326 +/- 4 +/- 19 pc, d(zeta Gem) = 360 +/- 13
+/- 22 pc, d(Y Oph) = 648 +/- 17 +/- 47 pc and d(L Car) = 542 +/- 2 +/- 49 pc.


title: Central Compact Objects in Supernova Remnants

abstract:
  There are point-like sources in central regions of several supernova remnants
which have not been detected outside the X-ray range. The X-ray spectra of
these Central Compact Objects (CCOs) have thermal components with blackbody
temperatures of 0.2-0.5 keV and characteristic sizes of 0.3-3 km. Most likely,
the CCOs are neutron stars born in supernova explosions. We overview their
observational properties, emphasizing the Chandra data, and compare them with
magnetars.


title:
Periodicities In The X-Ray Intensity Variations of TV Columbae: An
  Intermediate Polar

abstract:
  We present results from a temporal analysis of the longest and the most
sensitive X-ray observations of TV Columbae--an intermediate polar. The
observations were carried out with the RXTE PCA, ROSAT PSPC, and ASCA. Data
were analyzed using a 1-dimensional CLEAN and Bayesian algorithms. The presence
of a nearly sinusoidal modulation due to the spin of the white dwarf is seen
clearly in all the data, confirming the previous reports based on the EXOSAT
data. An improved period of 1909.7+/-2.5s is derived for the spin from the RXTE
data.The binary period of 5.5hr is detected unambiguously in X-rays for the
first time. Several side-bands due to the interaction of these periods are
observed in the power spectra, thereby suggesting contributions from both the
disk-fed and the stream-fed accretion for TV Col. The accretion disk could
perhaps be precessing as side-bands due to the influence of 4 day period on the
orbital period are seen. The presence of a significant power at certain
side-bands of the spin frequency indicates that the emission poles are
asymmetrically located. The strong power at the orbital side-bands seen in both
the RXTE and ROSAT data gives an indication for an absorption site fixed in the
orbital frame. Both the spin and the binary modulation are found to be
energy-dependent. Increased hardness ratio during a broad dip in the intensity
at binary phase of 0.75--1.0 confirms the presence of a strong attenuation due
to additional absorbers probably from an impact site of the accretion stream
with the disk or magnetosphere. Hardness ratio variations and the energy
dependent modulation depth during the spin modulation can be explained by
partially covered absorbers in the path of X-ray emission region in the
accretion stream.


title: The Luminosity Function of Lyman Alpha Emitters at Redshift z~5.7

abstract:
  We report results of a deep wide-field narrowband survey for redshift z~5.7
Ly alpha emitters carried out with SuprimeCam on Subaru 8.3-m telescope. Deep
narrowband imaging of the SSA22 field through a 120 A bandpass filter centered
at 8150 A was combined with deep multicolor RIz' SuprimeCam broadband imaging,
and BVRZ imaging taken with CFHT's CFH12K camera to select high-redshift galaxy
candidates. Spectroscopic observations were made using the new wide-field
multi-object DEIMOS spectrograph on Keck for 22 of the 26 candidate objects.
Eighteen objects were identified as z~5.7 Lyman alpha emitters, and a further
nineteenth candidate was identified based on an LRIS spectrum. At the 3.3 A
resolution of the DEIMOS spectra the asymmetric profile for Ly alpha emission
with its steep blue fall-off can be clearly seen. We use this to describe the
distribution of equivalent widths and the continuum color break properties for
z~5.7 Ly alpha galaxies compared with foreground objects. The large majority
(>75%) of Ly alpha lines have rest frame equivalent widths less than 240 A and
can be understood in terms of young star forming galaxies with a Salpeter
initial mass function for the stars. With narrowband selection criteria of I-N
> 0.7 and N<25.05 (AB mags) we find a surface density of Ly alpha emitters of
0.03 per square arcminute per (deltaz=0.1) to a limiting flux just under 2e-17
erg/cm2/s. The luminosity function of the Ly alpha emitters is similar to that
at lower redshifts to the lowest measurable luminosity of 1e43 ergs/s as is the
universal star formation rate based on their continuum properties. We note that
the objects are highly structured in both spatial and spectral properties on
the angular scale of the fields (~60 Mpc), and that multiple fields will have
to be averaged to accurately measure their ensemble properties.


title:
Sulphur and zinc abundances in Galactic stars and damped Lyman-alpha
  systems

abstract:
  High resolution spectra of 34 halo population dwarf and subgiant stars have
been obtained with VLT/UVES and used to derive sulphur abundances from the
8694.0, 8694.6 A and 9212.9, 9237.5 A SI lines. In addition, iron abundances
have been determined from 19 FeII lines and zinc abundances from the 4722.2,
4810.5 ZnI lines. The abundances are based on a classical 1D, LTE model
atmosphere analysis, but effects of 3D hydrodynamical modelling on the [S/Fe],
[Zn/Fe] and [S/Zn] ratios are shown to be small. We find that most halo stars
with metallicities in the range -3.2 < [Fe/H] < -0.8 have a near-constant
[S/Fe] = +0.3; a least square fit to [S/Fe] vs. {Fe/H] shows a slope of only
-0.04 +/- 0.01. Among halo stars with -1.2 < [Fe/H] < -0.8 the majority have
[S/Fe] ~ +0.3, but two stars (previously shown to have low [alpha/Fe] ratios)
have [S/Fe] ~ 0. For disk stars with [Fe/H] > -1, [S/Fe] decreases with
increasing [Fe/H]. Hence, sulphur behaves like other typical alpha-capture
elements, Mg, Si and Ca. Zinc, on the other hand, traces iron over three orders
of magnitude in [Fe/H], although there is some evidence for a small systematic
Zn overabundance ([Zn/Fe] ~ +0.1) among metal-poor disk stars and for halo
stars with [Fe/H] < -2.0. Recent measurements of S and Zn in ten damped
Ly-alpha systems (DLAs) with redshifts between 1.9 and 3.4 and zinc abundances
in the range -2.1 < [Zn/H] < -0.15 show an offset relative to the [S/Zn] -
[Zn/H] relation in Galactic stars. Possible reasons for this offset are
discussed, including low and intermittent star formation rates in DLAs.


title: Multi-wavelength study of the G 82.2+5.3 supernova remnant

abstract:
  We present the first CCD flux-calibrated images of the snr G 82.2+5.3 in
major optical emission lines. The [O III] 5007 line provides the first direct
evidence of optical emission originating from G 82.2+5.3. Filamentary emission
is detected in the west and east areas, roughly defining an ellipsoidal shell.
The [O III] emission is rather well correlated with the radio emission
suggesting their association, while typical fluxes are found in the range of
20-30x10^{-17} erg s^{-1} cm^{-2} arcsec^{-2}. Deep long-slit spectra taken at
specific positions of the remnant verify that the filamentary emission
originates from shock heated gas with shock velocities ~100 km/s and low
electron densities, while the diffuse [O III] emission in the south results
from photoionization processes. The X-ray surface brightness is quite patchy,
missing obvious limb brightening and is dominated by a bright bar-like emission
region which is off-set from the geometric center by ~9'. The X-ray emission is
thermal and requires two temperatures of 0.2 keV and 0.63 keV. The bright bar
region shows overabundant Mg, Si and Fe, which might indicate still radiating
ejecta matter. The azimuthally averaged radial surface profile is consistent
with the matter density changing with distance r from the center ~e^{-r/r_0}
with a characteristic angular length of 36', or, alternatively, with an
r^{-1/2} density profile. The matter inside the remnant is quite likely
structured like a porous cloudy medium. The average matter density is ~0.04 x
d_{1.6}^{-0.5}. Because of the low density and the long cooling times involved
the remnant is more likely to be in the adiabatic phase, which is consistent
with the densities derived for the X-ray plasma and the optical line emission,
but it is not excluded that is has reached the radiating phase.


title: Modelling of the continuum emission from Class 0 sources

abstract:
  Class 0 sources are objects representing the earliest phase of the
protostellar evolution. Since they are highly obscured by an extended dusty
envelope, these objects emit mainly in the far-infrared to millimetre
wavelength range. The analysis of their spectral energy distributions with wide
wavelength coverage allows to determine the bolometric temperature and
luminosity. However, a more detailed physical interpretation of the internal
physical structure of these objects requires radiative transfer modelling. We
present modelling results of spectral energy distributions of a sample of nine
Class 0 sources in the Perseus and Orion molecular clouds. The SEDs have been
simulated using a radiative transfer code based on the Monte Carlo method. We
find that a spherically symmetric model for the youngest Class 0 sources allows
to reproduce the observed SEDs reasonably well. From our modelling we derive
physical parameters of our sources, such as their mass, density distribution,
size, etc. We find a density structure of $\rho \sim r^{-2}$ for the collapsing
cores at young ages, evolving to $\rho \sim r^{-3/2}$ at later times.


title: The energy distribution of atoms in the field of thermal radiation

abstract:
  Using the principle of detailed balance and the assumption on the absorption
cross-section consistent with available astrophysical data, we obtain the
energy distribution of atoms in the field of thermal blackbody radiation and
show that this distribution diverges from the Boltzmann law. There is an
inversion of the high energy level population at sufficiently high
temperatures.


title: Microlensing towards M31: candidates and perspectives

abstract:
  Recent results of the SLOTT-AGAPE and POINT-AGAPE collaborations on a search
for microlensing events in direction of the Andromeda galaxy, by using the
pixel method, are reported. The detection of 4 microlensing events, some likely
to be due to self--lensing, is discussed. One microlensing light curve is shown
to be compatible with a binary lens. The present analysis still does not allow
us to draw conclusions on the MACHO content of the M31 galaxy.


title: Initial results from SECIS observations of the 2001 eclipse

abstract:
  SECIS observations of the June 2001 total solar eclipse were taken using an
Fe xiv 5303 A filter. Existing software was modified and new code was developed
for the reduction and analysis of these data. The observations, data reduction,
study of the atmospheric and instrumental effects, together with some
preliminary results are discussed. Emphasis is given to the techniques used for
the automated alignment of the 8000 images, the application of the a Trous
algorithm for noise filtering and the software developed for the automated
detection of intensity oscillations using wavelet analysis. In line with
findings from the 1999 SECIS total eclipse observations, intensity oscillations
with periods in the range of 20-30 s, both inside and just outside coronal
loops are also presented.


title:
Oscillating dark energy: a possible solution to the problem of eternal
  acceleration

abstract:
  We present a dark energy model with a double exponential potential for a
minimally coupled scalar field, which allows general exact integration of the
cosmological equations. The solution can perfectly emulate a $\Lambda$-term
model at low-medium redshift, exhibits tracking behavior, and does not show
eternal acceleration.


title:
B_gg revisited: The environments of low-excitation radio galaxies and
  unified models

abstract:
  Recent measurements of the galaxy clustering environments around
intermediate-redshift radio sources have suggested a systematic environmental
difference between radio galaxies and radio-loud quasars, in contradiction to
the predictions of simple unified models for the two classes of object. I show
that the apparent difference arises mainly as a result of the properties of
low-excitation radio galaxies included in the radio-galaxy sample, which tend
to lie in significantly richer environments. The environmental properties of
high-excitation radio galaxies and quasars are statistically consistent in the
redshift range 0.15 < z <0.4, as unified models would predict.


title: Exponential Potentials for Tracker Fields

abstract:
  We show that a general, exact cosmological solution, where dynamics of scalar
field is assigned by an exponential potential, fulfils all the issues of dark
energy approach, both from a theoretical point of view and in comparison with
available observational data. Moreover, tracking conditions are discussed, with
a new treatment of the well known condition $\Gamma>1$. We prove that the
currently used expression for $\Gamma$ is wrong.


title: The 2-8 keV cosmic X-ray background spectrum as observed with XMM-Newton

abstract:
  We have measured the spectrum of the Cosmic X-ray Background (CXB) in the 2-8
keV range with the high throughput EPIC/MOS instrument onboard XMM-Newton. A
large sample of high galactic latitude observations was used, covering a total
solid angle of 5.5 square degrees. Our study is based on a very careful
characterization and subtraction of the instrumental background, which is
crucial for a robust measurement of the faintest diffuse source of the X-ray
sky. The CXB spectrum is consistent with a power law having a photon index
Gamma=1.41+/-0.06 and a normalization of 2.46+/-0.09 photons/(cm^2 s sr keV) at
3 keV (~11.6 photons/(cm^2 s sr keV) at 1 keV), corresponding to a 2-10 keV
flux of (2.24+/-0.16)x10^(-11) erg/(cm^2 s deg) (90% confidence level,
including the absolute flux calibration uncertainty). Our results are in
excellent agreement with two of the most recent CXB measurements, performed
with BeppoSAX LECS/MECS data (Vecchi et al. 1999) and with an independent
analysis of XMM-Newton EPIC/MOS data (Lumb et al. 2002), providing a very
strong constrain to the absolute sky surface brightness in this energy range,
so far affected by a ~40% uncertainty. Our measurement immediately implies that
the fraction of CXB resolved by the recent deep X-ray observations in the 2-10
keV band is of 80+/-7% (1sigma), suggesting the existence of a new population
of faint sources, largely undetected within the current sensitivity limits of
the deepest X-ray surveys.


title: HI and Hot Gas in the Outskirts of the M81 Group

abstract:
  Results are presented from a wide area, high resolution HI synthesis survey
of the outer regions of the nearby M81 group, where internal (galactic) and
external (group-related) evolution processes can be studied simultaneously in
great detail. The survey encompasses the star forming dwarf galaxies M81dwA,
UGC4483, and HoII, where evidence of ram pressure stripping was recently
discovered. The data do not reveal any intergalactic HI, but the outer parts of
HoII are reminiscent of tidal tails. We argue however that those structures are
equally consistent with the latest ram pressure models including cooling. The
case for a hot intergalactic medium in this poor, spiral-only group is thus
still open. The survey also puts tight constraints on possible counterparts to
the local high velocity cloud population in an external group, reaching a 3
sigma column density of 10^19 atom/cm^2 and a 6 sigma limiting mass of 1.5x10^5
M_sun.


title:
Physically adequate proper reference system of a test observer and
  relativistic description of the GAIA attitude

abstract:
  A relativistic definition of the physically adequate proper reference system
of a test observer is suggested within the framework of the PPN formalism.
According to the nomenclature accepted within the GAIA project this reference
system is called Center-of-Mass Reference System (CoMRS). The interrelation
between the suggested definition of the CoMRS and the Resolutions 2000 on
relativity of the International Astronomical Union (IAU) are elucidated. The
tetrad representation of the CoMRS at its origin is also explicated. It is
demonstrated how to use that tetrad representation to calculate the relation
between the observed direction of a light ray and the corresponding coordinate
direction in the Barycentric Celestial Reference System of the IAU. It is
argued that the kinematically non-rotating CoMRS is the natural choice of the
reference system where the attitude of the observer (e.g. of the GAIA
satellite) should be modeled. The relativistic equations of rotational motion
of a satellite relative to its CoMRS are briefly discussed. A simple algorithm
for the attitude description of the satellite is proposed.


title:
Spectroscopic [Fe/H] for 98 extra-solar planet-host stars: Exploring the
  probability of planet formation

abstract:
  We present stellar parameters and metallicities, obtained from a detailed
spectroscopic analysis, for a large sample of 98 stars known to be orbited by
planetary mass companions (almost all known targets), as well as for a
volume-limited sample of 41 stars not known to host any planet. For most of the
stars the stellar parameters are revised versions of the ones presented in our
previous works. However, we also present parameters for 18 stars with planets
not previously published, and a compilation of stellar parameters for the
remaining 4 planet-hosts for which we could not obtain a spectrum. A comparison
of our stellar parameters with values of Teff, log(g), and [Fe/H] available in
the literature shows a remarkable agreement. The derived [Fe/H] values are then
used to confirm the previously known result that planets are more prevalent
around metal-rich stars. Furthermore, we confirm that the frequency of planets
is a strongly rising function of the stellar metallicity, at least for stars
with [Fe/H]>0. While only about 3% of the solar metallicity stars in the
CORALIE planet search sample were found to be orbited by a planet, this number
increases to more than 25% for stars with [Fe/H] above +0.3. Curiously, our
results also suggest that these percentages might remain relatively constant
for values of [Fe/H] lower than about solar, increasing then linearly with the
mass fraction of heavy elements. These results are discussed in the context of
the theories of planetary formation.


title: How old are the HII Galaxies?

abstract:
  Using a novel approach we have reanalized the question of whether the extreme
star forming galaxies known as HII galaxies are truly young or rejuvenated old
systems. We first present a method of inversion that applies to any monotonic
function of time describing the evolution of independent events. We show that,
apart from a normalization constant, the ``true'' time dependence can be
recovered from the inversion of its probability density function. We applied
the inversion method to the observed equivalent width of Hbeta (EW(Hbeta))
distribution for objects in the Terlevich and collaborators Spectrophotometric
Catalogue of HII galaxies and found that their global history of star formation
behaves much closer to the expectations of a continuos star formation model
than to an instantaneous one. On the other hand, when the inversion method is
applied to samples within a restricted metallicity range we find that their
history of star formation behaves much closer to what the instantaneous model
predicts.
  Our main conclusion is that, globally, the evolution of HII galaxies seems
consistent with a succession of short starbursts separated by quiescent periods
and that, while the emission lines trace the properties of the present burst,
the underlying stellar continuum traces the whole star formation history of the
galaxy. Thus, observables like the EW(Hbeta) that combine an emission line
flux, i.e. a parameter pertaining to the present burst, with the continuum
flux, i.e. a parameter that traces the whole history of star formation, should
not be used alone to characterize the present burst.


title:
Direct Numerical Simulations of Type Ia Supernovae Flames I: The
  Landau-Darrieus Instability

abstract:
  Planar flames are intrinsically unstable in open domains due to the thermal
expansion across the burning front--the Landau-Darrieus instability. This
instability leads to wrinkling and growth of the flame surface, and
corresponding acceleration of the flame, until it is stabilized by cusp
formation. We look at the Landau-Darrieus instability for C/O thermonuclear
flames at conditions relevant to the late stages of a Type Ia supernova
explosion. Two-dimensional direct numerical simulations of both single-mode and
multi-mode perturbations using a low Mach number hydrodynamics code are
presented. We show the effect of the instability on the flame speed as a
function of both the density and domain size, demonstrate the existence of the
small scale cutoff to the growth of the instability, and look for the proposed
breakdown of the non-linear stabilization at low densities. The effects of
curvature on the flame as quantified through measurements of the growth rate
and computation of the corresponding Markstein number. While accelerations of a
few percent are observed, they are too small to have any direct outcome on the
supernova explosion.


title: CMBfit: Rapid WMAP likelihood calculations with normal parameters

abstract:
  We present a method for ultra-fast confrontation of the WMAP cosmic microwave
background observations with theoretical models, implemented as a publicly
available software package called CMBfit, useful for anyone wishing to measure
cosmological parameters by combining WMAP with other observations. The method
takes advantage of the underlying physics by transforming into a set of
parameters where the WMAP likelihood surface is accurately fit by the
exponential of a quartic or sextic polynomial. Building on previous physics
based approximations by Hu et.al., Kosowsky et.al. and Chu et.al., it combines
their speed with precision cosmology grade accuracy. A Fortran code for
computing the WMAP likelihood for a given set of parameters is provided,
pre-calibrated against CMBfast, accurate to Delta lnL ~ 0.05 over the entire
2sigma region of the parameter space for 6 parameter ``vanilla'' Lambda CDM
models. We also provide 7-parameter fits including spatial curvature,
gravitational waves and a running spectral index.


title: Testing the Predictions of the Universal Structured GRB Jet Model

abstract:
  The two leading models for the structure of GRB jets are the uniform jet
model and the universal structured jet (USJ) model. In the latter, all GRB jets
are intrinsically identical and the energy per solid angle drops as the inverse
square of the angle from the jet axis. The simplicity of the USJ model gives it
a strong predictive power, including a specific prediction for the observed GRB
distribution as a function of both the redshift $z$ and the viewing angle
$\theta$. We show that the current sample of GRBs with known $z$ and estimated
$\theta$ does not agree with the predictions of the USJ model. This can be best
seen for a relatively narrow range in $z$, in which the USJ model predicts that
most GRBs should be near the upper end of the observed range in $\theta$, while
in the observed sample most GRBs are near the lower end of that range. Since
the current sample is very inhomogeneous (i.e. involves many different
detectors), it should be taken with care and cannot be used to rule out the USJ
model. Nevertheless, this sample strongly disfavors the USJ model. Comparing
the prediction for the observed GRB distribution both in $\theta$ and in $z$,
with a larger and more homogeneous GRB sample, like the one expected from
Swift, would either clearly rule out the USJ model, or alternatively, provide a
strong support for it. The test presented here is general, and can be used to
test any model that predicts both a luminosity function and a luminosity-angle
relation.


title: Dusty Debris Disks as Signposts of Planets: Implications for SIRTF

abstract:
  Submillimeter and near-infrared images of cool dusty debris disks and rings
suggest the existence of unseen planets. At dusty but non-imaged stars,
semi-major axes of associated planets can be estimated from the dust
temperature. For some young stars these semi-major axes are greater than an arc
second as seen from Earth. Such stars are excellent targets for sensitive
near-infrared imaging searches for warm planets. To probe the full extent of
the dust and hence of potential planetary orbits, SIRTF observations should
include measurements with the 160mu filter.


title: Microwave ISM Emission Observed by WMAP

abstract:
  We investigate the nature of the diffuse Galactic emission in the Wilkinson
Microwave Anisotropy Probe (WMAP) temperature anisotropy data. Substantial
dust-correlated emission is observed at all WMAP frequencies, far exceeding the
expected thermal dust emission in the lowest frequency channels (23, 33, 41
GHz). The WMAP team (Bennett et al.) interpret this emission as dust-correlated
synchrotron radiation, attributing the correlation to the natural association
of relativistic electrons produced by SNae with massive star formation in dusty
clouds, and deriving an upper limit of 5% on the contribution of Draine &
Lazarian spinning dust at K-band (23 GHz). We pursue an alternative
interpretation that much, perhaps most, of the dust-correlated emission at
these frequencies is indeed spinning dust, and explore the spectral dependence
on environment by considering a few specific objects as well as the full sky
average. Models similar to Draine & Lazarian spinning dust provide a good fit
to the full-sky data. The full-sky fit also requires a significant component
with free-free spectrum uncorrelated with \Halpha, possibly hot (~million K)
gas within 30 degrees of the Galactic center.


title:
Resolution of the MACHO-LMC-5 Puzzle: The Jerk-Parallax Microlens
  Degeneracy

abstract:
  By extending the constant-acceleration analysis of Smith, Mao, & Paczynski to
include jerk, I show that microlens parallax measurements are subject to a
four-fold discrete degeneracy. The new degeneracy is characterized by a
projected velocity \tilde v_j =
-(3/4)\csc\beta_\ec(\cos^2\psi\sin^2\beta_\ec+\sin^2\psi)^{3/2}v_earth, where
\beta_\ec is the ecliptic latitude, \psi is the phase of the Earth's orbit
relative to opposition at the time of the event maximum, and v_earth=30 km/s is
the speed of the Earth. The degeneracy becomes important when the lens
projected velocity \tilde v is of order \tilde v_j. For events toward the Large
Magellanic Cloud, \tilde v_j\simeq (3/4)v_earth, so this degeneracy is
important primarily for lenses in the Milky Way disk. In particular, it solves
the puzzle of MACHO-LMC-5, whose microlens parallax measurement had yielded
mass and distance determinations for the lens that were inconsistent with
photometric estimates. Toward the Galactic bulge, \tilde v_j ranges from about
0.2 km/s at the solstice to about 200 km/s at the equinoxes, so the effect of
the degeneracy depends strongly on the peak time of the event. The degeneracy
applies mainly to events with Einstein timescales, t_E < yr/2pi.


title: Cosmological X-Ray Flashes from Off-Axis Jets

abstract:
  The <V/Vmax> of the cosmological X-ray flashes detected by WFC/BeppoSAX is
calculated theoretically in a simple jet model. The total emission energy from
the jet is assumed to be constant. We find that if the jet opening half-angle
is smaller than 0.03 radian, off-axis emission from sources at z<~4 can be
seen. The theoretical <V/Vmax> is less than 0.4, which is consistent with the
observational result of 0.27+/-0.16 at the 1-sigma level. This suggests that
the off-axis GRB jet with the small opening half-angle at the cosmological
distance can be identified as the cosmological X-ray flash.


title: GRB980425 in the Off-Axis Jet Model of the Standard GRBs

abstract:
  Using a simple off-axis jet model of GRBs, we can reproduce the observed
unusual properties of the prompt emission of GRB980425, such as the extremely
low isotropic equivalent gamma-ray energy, the low peak energy, the high
fluence ratio, and the long spectral lag when the jet with the standard energy
of ~10^{51} ergs and the opening half-angle of \Delta\theta=~10-30 degree is
seen from the off-axis viewing angle ~\Delta\theta+10/\gamma, where \gamma is a
Lorentz factor of the jet. For our adopted fiducial parameters, if the jet that
caused GRB 980425 is viewed from the on-axis direction, the intrinsic peak
energy Ep(1+z) is ~2.0-4.0 MeV, which corresponds to those of GRB990123 and
GRB021004. Our model might be able to explain the other unusual properties of
this event. We also discuss the connection of GRB980425 in our model with the
X-ray flash, and the origin of a class of GRBs with small E_\gamma such as
GRB030329, GRB980329, GRB981226, and so on.


title:
The Cores of the Fe K Lines in Seyfert I Galaxies Observed by the
  Chandra High Energy Grating

abstract:
  We report on the results of 18 observations of the core, or peak, of the Fe K
emission line at $\sim 6.4$ keV in 15 Seyfert I galaxies using the {\it
Chandra} High Energy Grating (HEG). These data afford the highest precision
measurements of the peak energy of the Fe K line, and the highest spectral
resolution measurements of the width of the core of the line to date. We were
able to measure the peak energy in 17 data sets, and, excluding a very deep
observation of NGC 3783, we obtained a weighted mean of $6.404 \pm 0.005$ keV.
In all 15 sources the two-parameter, 99% confidence errors on the line peak
energy do not exclude fluorescent $K\alpha$ line emission from Fe {\sc i},
although two sources (Mkn 509 and 3C 120) stand out as very likely being
dominated by $K\alpha$ emission from Fe {\sc xvii} or so. We were able to
measure the line core width in 14 data sets and obtained a weighted mean of
2380 +/- 760 km/s FWHM (excluding the NGC 3783 deep exposure), a little larger
than the instrument resolution. However, there is evidence of underlying broad
line emission in at least 4 sources. In fact, the width of the peak varies
widely from source to source and it may in general have a contribution from the
outer parts of an accretion disk {\it and} more distant matter. For the disk
contribution to also peak at 6.4 keV requires greater line emissivity at
hundreds of gravitational radii than has been deduced from previous studies of
the Fe K line.


title: New Planetary Nebulae in the Northern Galactic Plane

abstract:
  We present deep Halpha+[N II] CCD images of selected new Planetary Nebulae
(PNe) discovered through an [O III] 5007 A emission line survey in the Galactic
Bulge region with l > 0 deg. In total, we detected more than 200 objects,
including 45 new PNe. Deep Halpha+[N II] CCD images as well as low resolution
spectra were obtained for the new PNe in order to study them in detail. Their
first morphological study suggests that most of them are round (60%), while 31%
and 9% are elliptical and bipolar, respectively. 63% of the round PNe present
ring-like structure while 37% are compact.


title:
Chemical Enrichment in Damped Lyman Alpha Systems From Hierarchical
  Galaxy Formation Models

abstract:
  We investigate chemical enrichment in Damped Lyman alpha (DLA) systems in the
hierarchical structure formation scenario using a semi-analytic model of galaxy
formation. The model developed by Nagashima, Totani, Gouda and Yoshii takes
into account various selection effects on high-redshift galaxies and can show
fundamental observational properties of galaxies, such as luminosity functions
and number-magnitude/redshift relations. DLA systems offer the possibilities of
measuring metal abundance more accurately than faint galaxies. For example,
recent measurements of zinc abundance can provide good evidence for
understanding the processes of metal pollution and star formation in DLA
systems because zinc is virtually unaffected by dust depletion. Here we focus
on this advantage for observation in order to explore the metallicity evolution
in DLA systems at high redshifts. We can consistently show the metallicity
evolution for reasonable models which also reproduce fundamental properties of
local galaxy population. This result suggests that the chemical evolution of
DLA systems can be consistently reconciled with the observational features of
typical galaxies. We also investigate other properties of DLA systems (column
density distribution and mass density of cold gas), and find that star
formation in massive galaxies should be more active than that in low-mass ones.
This is consistent with the results by Nagashima et al. and Cole et al. in
which the star formation timescale is set by reproducing cold gas mass fraction
in local spiral galaxies. Finally we discuss host galaxies associated with DLA
systems. We conclude that they primarily consist of sub-L* and/or dwarf
galaxies from the observations.


title: Automatic detection of arcs and arclets formed by gravitational lensing

abstract:
  We present an algorithm developed particularly to detect gravitationally
lensed arcs in clusters of galaxies. This algorithm is suited for automated
surveys as well as individual arc detections. New methods are used for image
smoothing and source detection. The smoothing is performed by so-called
anisotropic diffusion, which maintains the shape of the arcs and does not
disperse them. The algorithm is much more efficient in detecting arcs than
other source finding algorithms and the detection by eye.


title: The Disk Mass project; science case for a new PMAS IFU module

abstract:
  We present our Disk Mass project as the main science case for building a new
fiber IFU-module for the PMAS spectrograph, currently mounted at the Cassegrain
focus of the 3.5m telescope on Calar Alto. Compared to traditional long-slit
observations, the large light collecting power of 2-dimensional Integral Field
Units dramatically improves the prospects for performing spectroscopy on
extended low surface brightness objects with high spectral resolution. This
enables us to measure stellar velocity dispersions in the outer disk of normal
spiral galaxies. We describe some results from a PMAS pilot study using the
existing lenslet array, and provide a basic description of the new fiber
IFU-module for PMAS.


title: An XMM-Newton observation of the dynamically active binary cluster A1750

abstract:
  We present results from the XMM-Newton observation of the binary cluster
A1750 at z = 0.086. We have performed a detailed study of the surface
brightness, temperature and entropy distribution and confirm that the two main
clusters of the system (A1750 N and A1750 C) have just started to interact.
  From the temperature distribution, we calculate that they are likely to merge
sometime in the next 1 Gyr. The more massive cluster, A1750 C, displays a more
complicated temperature structure than expected. We detect a hot region
associated with a density jump ~450 kpc east of the cluster centre, which
appears to be a shock wave. This shock is not connected with the binary merger,
but it is intrinsic to A1750 C itself. From simple physical arguments and
comparison with numerical simulations, we argue that this shock is related to a
merging event that A1750 C has suffered in the past 1-2 Gyr. The larger scale
structure around A1750 suggests that the system belongs to a rich supercluster,
which would presumably increase the likelihood of merger events. These new
XMM-Newton data thus show that A1750 is a complex system, where two clusters
are starting to interact before having re-established equilibrium after a
previous merger. This merger within a merger indicates that the present day
morphology of clusters may depend not only on on-going interactions or the last
major merging event, but also on the more ancient merger history, especially in
dense environments.


title: BeppoSAX observations of soft X-ray Intermediate Polars

abstract:
  We present broad-band (0.1--90keV) spectral and temporal properties of the
three Intermediate Polars, RE0751+144 (PQ Gem), RXJ0558.0+5353 (V405Aur) and
RXJ1712.6-2414 (V2400 Oph) based on simultaneous soft and hard X-ray
observations with the BeppoSAX satellite. The analysis of their spectra over
the wide energy range of BeppoSAX instruments allows us to identify the soft
and hard X-ray components and to determine simultaneously their temperatures.
The black--body temperatures of the irradiated poles of the white dwarf
atmosphere are found to be 60--100eV, much higher than those found in their
synchronous analogues, the Polars. The temperature of the optically thin
post--shock plasma is well constrained in RXJ1712.6-2414 and in RE0751+144 (13
and 17keV) and less precisely determined in RXJ0558.0+5353. In the first two
systems evidence of subsolar abundances is found, similarly to what estimated
in other magnetic Cataclysmic Variables. A Compton reflection component is
present in RXJ0558.0+5353 and in RE0751+144 and it is favoured in
RXJ1712.6-2414. Its origin is likely at the irradiated white dwarf surface.
Although these systems share common properties (soft X-ray component and
optical polarized radiation), their X-ray power spectra and light curves at
different energies suggest accretion geometries which cannot be reconciled with
a single and simple configuration.


title: AA Dor - An Eclipsing sdOB - Brown Dwarf Binary

abstract:
  AA Dor is an eclipsing, close, post common-envelope binary consisting of a
sdOB primary star and an unseen secondary with an extraordinary small mass -
formally a brown dwarf. The brown dwarf may have been a former planet which
survived a common envelope phase and has even gained mass.
  A recent determination of the components' masses from results of NLTE
spectral analysis and subsequent comparison to evolutionary tracks shows a
discrepancy to masses derived from radial-velocity and the eclipse curves.
Phase-resolved high-resolution and high-SN spectroscopy was carried out in
order to investigate on this problem.
  We present results of a NLTE spectral analysis of the primary, an analysis of
its orbital parameters, and discuss possible evolutionary scenarios.


title: The lensing properties of the Sersic model

abstract:
  It is well known that the surface brightness of elliptical galaxies and of
bulges of spiral galaxies is best fitted by the Sersic r^{1/n} profile. It is
thus interesting to explore the lensing properties of the Sersic model because
of its wide range of applicability. To this aim, we evaluate the lensing
potential, the deflection angle, the time delay between the images and the a
mplification for a circularly symmetric lens whose surface density is described
by the Sersic profile. We estimate the same quantities also adding a shear term
to the deflection potential in order to study (at the lowest order) the impact
of deviations from radial symmetry or the contribution from other nearby
lenses. Moreover, we investigate the systematic errors due to the use of a de
Vaucouleurs profile instead of the correct Sersic model also taking into
account the presence of a dark halo.


title:
The faint neutron star soft X-ray transient SAX J1810.8-2609 in
  quiescence

abstract:
  We present the analysis of a 35 ksec long Chandra observation of the neutron
star soft X-ray transient (SXT) SAX J1810.8-2609. We detect three sources in
the field of view. The position of one of them is consistent with the location
of the ROSAT error circle of SAX J1810.8-2609. The accurate Chandra position of
that source coincides with the position of the proposed optical counterpart,
strengthening the identification as the counterpart. We detected the neutron
star SXT system in quiescence at an unabsorbed luminosity of ~1x10^32 erg s^-1
(assuming a distance of 4.9 kpc). This luminosity is at the low-end of
quiescent luminosities found in other neutron star SXTs. This renders support
to the existence of a group of faint soft X-ray transients of which the
accreting millisecond X-ray pulsar SAX J1808.4-3658 is the most prominent
member. The quiescent spectrum of SAX J1810.8-2609 is well-fit with an absorbed
power law with photon index of 3.3+-0.5. With a value of 3.3x10^21 cm^-2 the
Galactic absorption is consistent with the value derived in outburst. Since the
spectra of quiescent neutron star SXTs are often fit with an absorbed blackbody
or neutron star atmosphere plus power-law model we also fitted the spectrum
using those fit functions. Both models provide a good fit to the data. If
cooling of the neutron star core and/or crust is responsible for the soft part
of the spectrum the time averaged mass accretion rate must have been very low
(~5.7x10^-13 Msun yr^-1; assuming standard core cooling only) or the neutron
star must be massive. We also discuss the possibility that the thermal spectral
component in neutron stars in quiescence is produced by residual accretion.


title: An MHD-driven Disk Wind Outflow in SDSS J0300+0048?

abstract:
  The outflow in SDSS J030000.56+004828.0 has the highest low-ionization
metal-line column density yet reported for a broad absorption line quasar. The
absorption from different ions is also segregated as a function of velocity in
a way that can only be explained by a disk wind outflow. Furthermore, the
presence of the such large column densities of gas at the high observed outflow
velocities may be incompatible with purely radiative acceleration. MHD
contributions to the acceleration should be considered seriously.


title:
Curvature and isocurvature perturbations in a three-fluid model of
  curvaton decay

abstract:
  We study the evolution of the cosmological perturbations after inflation in
curvaton models where the non-relativistic curvaton decays into both radiation
and a cold dark matter component. We calculate the primordial curvature and
correlated isocurvature perturbations inherited by the radiation and cold dark
matter after the curvaton has decayed. We give the transfer coefficient in
terms of the initial curvaton density relative to the curvaton decay rate.


title:
Inhomogeneous reheating scenario with low scale inflation and/or MSSM
  flat directions

abstract:
  We discuss the constraints on the inhomogeneous reheating scenario. In
particular, we discuss the prospects for low scale inflation with a Hubble
constant of the order of the gravitino mass, and the possibility that an MSSM
flat direction is responsible for the density fluctuations. Thermal effects are
generically fatal for the scenario, and can only be avoided for small enough
mass and couplings of the flat direction field, excluding MSSM flat directions.
Prompt decay at the end of inflation bypasses thermal constraints, and is
compatible with both low scale inflation and MSSM flat directions. However, the
level of non-Gaussianity is acceptably small only for a small window of
inflaton mass and couplings. The upshot is that tuning of parameters is needed
for the inhomogeneous reheating scenario to work.


title:
Abundance patterns in the low-metallicity emission-line galaxies from
  the Early Data Release of the Sloan Digital Sky Survey

abstract:
  We have derived element abundances in 310 emission-line galaxies from the
Early Data Release of the Sloan Digital Sky Survey (SDSS) for which the [O {\sc
iii}] 4363 emission line was detected, allowing abundance determination by
direct methods. We found no extremely metal-deficient galaxy (Z<Zsun/12),
probably as a consequence of selection effects in the SDSS sample. The oxygen
abundance 12 + log O/H of the SDSS galaxies sample lies in the range from ~7.6
(Zsun/12) to ~8.4 (Zsun/2). This sample is merged with a sample of ~100 blue
compact dwarf galaxies with high quality spectra containing some very
low-metallicity objects to study the abundance patterns of low-metallicity
emission-line galaxies. We find that the $\alpha$ element-to-oxygen abundance
ratios do not show any significant trends with the oxygen abundance, in
agreement with previous studies. The Fe/O abundance ratio is smaller than the
solar value, which we interpret as an indication that type Ia supernovae have
not yet appeared in these galaxies, implying an age of less than 1-2 Gyr.
However, a slight decrease of the Fe/O abundance ratio with increasing
metallicity suggests some depletion of iron onto dust in the galaxies with
higher metallicities. The N/O abundance ratio ranges from log N/O= -1.6 to
-0.8. The fact that no galaxy with log N/O < -1.6 was discovered implies that
local low-metallicity emission-line galaxies are of a different nature than
high-redshift damped Lyalpha systems with log N/O of ~-2.3 and that their ages
are probably larger than 100-300 Myr. Our data indicate the existence of a
gradual nitrogen enrichment on a time-scale of a few Myr.


title:
Proper motion surveys of the young open clusters Alpha Persei and the
  Pleiades

abstract:
  In this paper we present surveys of two open clusters using photometry and
accurate astrometry from the SuperCOSMOS microdensitometer. These use plates
taken by the Palomar Oschin Schmidt Telescope giving a wide field ($5^{\circ}$
from the cluster centre in both cases), accurate positions and a long time
baseline for the proper motions. Distribution functions are fitted to proper
motion vector point diagrams yeilding formal membership probabilities.
Luminosity and mass functions are then produced along with a catalogue of high
probability members. Background star contamination limited the depth of the
study of Alpha Per to R=18. Due to this the mass function found for this
cluster could only be fitted with a power law ($\xi(m) = m^{-\alpha}$) with
$\alpha=0.86^{+0.14}_{-0.19}$. However with the better seperation of the
Pleiades' cluster proper motion from the field population results were obtained
down to R=21. As the mass function produced for this cluster extends to lower
masses it is possible to see the gradient becoming increasingly shallow. This
mass function is well fitted by a log normal distribution.


title: The GraF instrument for imaging spectroscopy with the adaptive optics

abstract:
  The GraF instrument using a Fabry-Perot interferometer cross-dispersed with a
grating was one of the first integral-field and long-slit spectrographs built
for and used with an adaptive optics system. We describe its concept, design,
optimal observational procedures and the measured performances. The instrument
was used in 1997-2001 at the ESO 3.6 m telescope equipped with ADONIS adaptive
optics and SHARPII+ camera. The operating spectral range was 1.2 - 2.5 microns.
We used the spectral resolution from 500 to 10 000 combined with the angular
resolution of 0.1" - 0.2". The quality of GraF data is illustrated by the
integral field spectroscopy of the complex 0.9" x 0.9" central region of Eta
Car in the 1.7 microns spectral range at the limit of spectral and angular
resolutions.


title: HI kinematics in a massive spiral galaxy at z=0.89

abstract:
  We present a kinematic model of the neutral-hydrogen in the spiral galaxy of
the lens system PKS1830-211, based on a Multi Element Radio-Linked
Interferometer (MERLIN) 1.4-GHz radio map and the integrated and redshifted
21-cm hydrogen absorption-line profile as measured with the Westerbork
Synthesis Radio Telescope (WSRT). Degeneracies in the models do not allow a
unique determination of the kinematic center and forthcoming deeper Hubble
Space Telescope observations with the Advanced Camera for Surveys (ACS) are
required to break this degeneracy. Even so, we measure the inclination of the
hydrogen disk: i=(17-32) deg., indicating a close-to face-on spiral galaxy. The
optical depth increases with radius over the extent of the Einstein ring,
suggesting HI depletion towards the lens center. The latter could be due to
star formation or conversion of HI in to molecular hydrogen because of a higher
metalicity/dust content in the galaxy center. The neutral hydrogen optical
depth gives N_HI= 2x10^21 cm^-2 at r=5.0 h_{70}^-1 kpc in the disk (T_s=100K),
comparable to local spiral galaxies. Our study shows that planned new radio
telescopes (i.e. ALMA, LOFAR and SKA) -- which will discover large numbers of
similar lens systems -- are powerful new tools to probe the internal structure,
kinematics and evolution of spiral galaxies in detail to z>=1, as well as their
neutral-hydrogen (and molecular) content, thereby complementing studies of HI
emission from spirals at z<=1 and damped Ly-alpha systems to z>>1.


title:
The Effects of Low-Temperature Dielectronic Recombination on the
  Relative Populations of the Fe M-Shell States

abstract:
  We examine the effects of low-temperature, or $\Delta$$n = 0$, dielectronic
recombination (DR) on the ionization balance of the Fe M-Shell (Fe IX through
Fe XVI). Since $\Delta$$n = 0$ rates are not available for these ions, we have
derived estimates based on the existing rates for the first four ionization
states of the CNO sequence and newly calculated rates for L-shell ions of 3rd
row elements and Fe. For a range of ionization parameter and column density
applicable to the intrinsic absorbers detected in {\it ASCA}, {\it Chandra},
and {\it XMM-Newton} observations of Seyfert galaxies, we generated two grids
of photoionization models, with and without DR. The results show that the
ionization parameter at which the population of an Fe M-shell ion peakscan
increase in some cases by factor $>$ 2 when these rates are included. More
importantly, there are dramatic changes in the range in ionization parameter
over which individual M-shell ions contain significant fractions of the total
Fe (e.g. $>$ 10%) in the plasma. These results may explain the mismatch between
the range of Fe ionization states detected in the X-ray spectra of Seyferts,
identified by the energies of the M-Shell Unresolved Transition Array, and
those predicted by photoionization models of the X-ray absorbers that reproduce
lines of second and third row elements. The results suggest that care should be
taken in using 3rd and 4th row ions to constrain the physical conditions in
photoionized X-ray plasmas until accurate DR rates are available. This
underscores the importance of atomic physics in interpreting astronomical
spectroscopy.


title: Microlensing of gamma ray bursts by stars and MACHOs

abstract:
  The microlensing interpretation of the optical afterglow of GRB 000301C seems
naively surprising, since a simple estimate of the stellar microlensing rate
gives less than one in four hundred for a flat Omega_Lambda=0.7 cosmology,
whereas one event was seen in about thirty afterglows. Considering baryonic
MACHOs making up half of the baryons in the universe, the microlensing
probability per burst can be roughly 5% for a GRB at redshift z=2. We explore
two effects that may enhance the probability of observing microlensed gamma-ray
burst afterglows: binary lenses and double magnification bias. We find that the
consideration of binary lenses can increase the rate only at the ~15% level. On
the other hand, because gamma-ray bursts for which afterglow observations exist
are typically selected based on fluxes at widely separated wavebands which are
not necessarily well correlated (e.g. localization in X-ray, afterglow in
optical/infrared), magnification bias can operate at an enhanced level compared
to the usual single-bias case. We find that existing estimates of the slope of
the luminosity function of gamma-ray bursts, while as yet quite uncertain,
point to enhancement factors of more than three above the simple estimates of
the microlensing rate. We find that the probability to observe at least one
microlensing event in the sample of 27 measured afterglows can be 3-4% for
stellar lenses, or as much as 25 Omega_lens for baryonic MACHOs. We note that
the probability to observe at least one event over the available sample of
afterglows is significant only if a large fraction of the baryons in the
universe are condensed in stellar-mass objects. (ABRIDGED)


title: Influence of an Internal Magnetar on Supernova Remnant Expansion

abstract:
  Most of the proposed associations between magnetars and supernova remnant
suffer from age problems. Usually, supernova remnants ages are determined from
an approximation of the Sedov-Taylor phase relation between radius and age, for
a fixed energy of the explosion ~ 10^{51} erg. Those ages do not generally
agree with the characteristic ages of the (proposed) associated magnetars. We
show quantitatively that, by taking into account the energy injected on the
supernova remnant by magnetar spin-down, a faster expansion results, improving
matches between characteristic ages and supernova remnants ages. However, the
magnetar velocities inferred from observations would inviabilize some
associations. Since characteristic ages may not be good age estimators, their
influence on the likelihood of the association may not be as important.
  In this work we present simple numerical simulations of supernova remnants
expansion with internal magnetars, and apply it to the observed objects. A
short initial spin period, thought to be important for the very generation of
the magnetic field, is also relevant for the modified expansion of the remnant.
We next analyze all proposed associations case-by-case, addressing the
likelyhood of each one, according to this perspective. We consider a larger
explosion energy and reasses the characteristic age issue, and conclude that
about 50% of the associations can be true ones, provided SGRs and AXPs are
magnetars.


title:
On the Continuing Formation of the Andromeda Galaxy: Detection of HI
  Clouds in the M31 Halo

abstract:
  Green Bank Telescope (GBT) 21cm observations have revealed a faint, yet
extensive HI cloud population surrounding the Andromeda Galaxy (M31). The
newfound objects are likely analogs to the high-velocity HI clouds (HVCs) seen
around the Milky Way. At least 20 discrete features are detected within 50 kpc
of the M31 disk, with radial velocities that are comparable to those of outer
disk rotation. In addition, a filamentary ``halo'' component of at least 30 kpc
extent is concentrated at the M31 systemic velocity. Some of the discrete
features are organized into elongated systems with velocity continuity,
suggestive of tidal streams. The discrete population can be characterized by a
steep power-law distribution of number versus HI mass in the range between 10^5
and 10^7 M_sun. The velocity line-width of discrete clouds is correlated with
the cloud HI mass: such that if the clouds are gravitationally bound this
implies a dark- to HI mass ratio of ~ 100:1. Possible origins for the discrete
and ``halo'' M31 features include: a Local Group ``cooling flow'', tidal debris
from recent mergers or interactions, and the gaseous counterparts of low mass
dark-matter halos.


title: Very Isolated Early-Type Galaxies

abstract:
  We use the Karachentseva (1973) ``Catalogue of Very Isolated Galaxies'' to
investigate a candidate list of >100 very isolated early-type galaxies.
Broad-band imaging and low resolution spectroscopy are available for a large
fraction of these candidates and result in a sample of 102 very isolated
early-type galaxies, including 65 ellipticals and 37 S0 galaxies. Many of these
systems are quite luminous and the resulting optical luminosity functions of
the Es and early-types (E+S0s) show no statistical differences when compared to
luminosity functions dominated by group and cluster galaxies. However, whereas
S0s outnumber Es 4:1 in the CfA survey, isolated Es outnumber S0s by nearly
2:1. We conclude that very isolated elliptical galaxies show no evidence for a
different formation and/or evolution process compared to Es formed in groups or
clusters, but that most S0s are formed by a mechanism (e.g., gas stripping)
that occurs only in groups and rich clusters. Our luminosity function results
for ellipticals are consistent with very isolated ellipticals being formed by
merger events, in which no companions remain.
  CHANDRA observations were proposed to test specifically the merger hypothesis
for isolated ellipticals. However, this program has resulted in the observation
of only one isolated early-type galaxy, the S0 KIG 284, which was not detected
at a limit well below that expected for a remnant group of galaxies. Therefore,
the hypothesis remains untested that very isolated elliptical galaxies are the
remains of a compact group of galaxies which completely merged.


title: Self-Gravitating Eccentric Disk Models for the Double Nucleus of M31

abstract:
  We present new dynamical models of weakly self-gravitating, finite dispersion
eccentric stellar disks around central black holes for the double nucleus of
M31. The disk is fixed in a frame rotating at constant precession speed, and is
populated by stars on quasi-periodic orbits whose parents are numerically
integrated periodic orbits in the total potential. A distribution of
quasi-periodic orbits about a given parent is approximated by a distribution of
Kepler orbits dispersed in eccentricity and orientation, using an approximate
phase-space distribution function written in terms of the integrals of motion
in the Kepler problem. We use these models, along with an optimization routine,
to fit available published kinematics and photometry in the inner 2 arcseconds
of the nucleus. A grid of 24 best-fit models is computed to accurately
constrain the mass of the central black hole and nuclear disk parameters. We
find that the supermassive black hole in M31 has mass $M_{BH} = 5.62 \pm 0.66
\times 10^7 \msun$, which is consistent with the observed correlation between
the central black hole mass and the velocity dispersion of its host spheroid.
Our models precess rapidly, at $\Omega = 36.5 \pm 4.2 \kmspc$, and possess a
characteristic radial eccentricity distribution, which gives rise to
multi-modal line of sight velocity distributions along lines of sight near the
black hole. These features can be used as sensitive discriminants of disk
structure.


title:
Exploring Cluster Physics with High-Resolution Sunyaev-Zel'dovich Effect
  Images and X-Ray Data: The Case of the Most X-Ray-Luminous Galaxy Cluster RX
  J1347-1145

abstract:
  Foreseeing the era of high spatial resolution measurements of the
Sunyaev-Zel'dovich effect (SZE) in clusters of galaxies, we present a prototype
analysis of this sort combined with Chandra X-ray data. It is applied
specifically to RX J1347-1145 at z=0.451, the most X-ray-luminous galaxy
cluster known, for which the highest resolution SZE and X-ray images are
currently available. We demonstrate that the combined analysis yields a unique
probe of complex structures in the intracluster medium, offering determinations
of their temperature, density, and line-of-sight extent. For a subclump in RX
J1347-1145, previously discovered in our SZE map, the temperature inferred
after removing the foreground and background components is well in excess of 20
keV, indicating that the cluster has recently undergone a violent merger.
Excluding the region around this subclump, the SZE signals in submillimeter to
centimeter bands (350, 150, and 21 GHz) are all consistent with those expected
from Chandra X-ray observations. We further present a temperature deprojection
technique based on the SZE and X-ray images, without any knowledge of spatially
resolved X-ray spectroscopy. The methodology presented here will be applicable
to a statistical sample of clusters available in the future SZE surveys.


title: Simulations of Large-Scale Structure in the New Millennium

abstract:
  Simulations of large-scale structure in the universe have played a vital role
in observational cosmology since 1980's in particular. Their important role
will definitely continue to be true in the 21st century. Rather the
requirements for simulations in the precision cosmology era will become more
progressively demanding; they are supposed to fill the missing link in an
accurate and reliable manner between the ``initial'' condition at z=1000
revealed by WMAP and the galaxy/quasar distribution at z=0 - 6 surveyed by 2dF
and SDSS. In this review, I will summarize what we have learned so far from the
previous cosmological simulations, and discuss several remaining problems for
the new millennium.


title: The motion of the Solar System and the Michelson-Morley experiment

abstract:
  Historically, the Michelson-Morley experiment has played a crucial role for
abandoning the idea of a preferred reference frame, the ether, and for
replacing Lorentzian Relativity with Einstein's Special Relativity. However,
our re-analysis of the Michelson-Morley original data, consistently with the
point of view already expressed by other authors, shows that the experimental
observations have been misinterpreted. Namely, the fringe shifts point to a
non-zero observable Earth's velocity v_obs = 8.4 +/- 0.5 km/s. Assuming the
existence of a preferred reference frame, and using Lorentz transformations to
extract the kinematical Earth's velocity that corresponds to this v_obs, we
obtain a real velocity, in the plane of the interferometer, v_earth = 201 +/-
12 km/s. This value is in excellent agreement with Miller's calculated value
v_earth = 203 +/- 8 km/s and suggests that the magnitude of the fringe shifts
is determined by the typical velocity of the Solar System within our galaxy.
This conclusion, which is also consistent with the results of all other
classical experiments, leads to an alternative interpretation of the
Michelson-Morley type of experiments. Contrary to the generally accepted ideas
of last century, they provide experimental evidence for the existence of a
preferred reference frame. This point of view is also consistent with the most
recent data for the anisotropy of the two-way speed of light in the vacuum.


title:
Detection and discrimination of cosmological non-Gaussian signatures by
  multi-scale methods

abstract:
  Recent Cosmic Microwave Background (CMB) observations indicate that the
temperature anisotropies arise from quantum fluctuations in the inflationary
scenario. In the simplest inflationary models, the distribution of CMB
temperature fluctuations should be Gaussian. However, non-Gaussian signatures
can be present. They might have different origins and thus different
statistical and morphological characteristics.
  In this context and motivated by recent and future CMB experiments, we search
for, and discriminate between, different non-Gaussian signatures. We analyse
simulated maps of three cosmological sources of temperature anisotropies:
Gaussian distributed CMB anisotropies from inflation, temperature fluctuations
from cosmic strings and anisotropies due to the kinetic Sunyaev-Zel'dovich (SZ)
effect both showing a non-Gaussian character. We use different multi-scale
methods, namely, wavelet, ridgelet and curvelet transforms. The sensitivity and
the discriminating power of the methods is evaluated using simulated data sets.
  We find that the bi-orthogonal wavelet transform is the most powerful for the
detection of non-Gaussian signatures and that the curvelet and ridgelet
transforms characterise quite precisely and exclusively the cosmic strings.
They allow us thus to detect them in a mixture of CMB + SZ + cosmic strings. We
show that not one method only should be applied to understand non-Gaussianity
but rather a set of different robust and complementary methods should be used.


title: A view of PKS 2155-304 with XMM-Newton Reflection Grating Spectrometers

abstract:
  We present the high resolution X-ray spectrum of the BL Lac object PKS
2155-304 taken with the RGS units onboard XMM-Newton in November 2000. We
detect a OVII Kalpha resonant absorption line from warm/hot local gas at 21.59A
(~4.5 sigma detection). The line profile is possibly double peaked. We do not
confirm the strong 20.02 A absorption line seen with Chandra and interpreted as
z~0.05 OVIII Kalpha. A 3sigma upper limit of 14 mA on the equivalent width is
set. We also detect the ~23.5 A interstellar OI 1s-->2p line and derive a
factor <=1.5 subsolar O/H ratio in the ISM along PKS 2155-304 line of sight.


title: Tracing the relation between black holes and dark haloes

abstract:
  We present new velocity dispersion measurements for a set of 12 spiral
galaxies and use them to derive a more accurate V_c - sigma relation which
holds for a wide morphological range of galaxies. Combined with the M_BH -
sigma relation, this relation can be used as a tool to estimate supermassive
black hole (SMBH) masses by means of the asymptotic circular velocity. Together
with the Tully-Fisher relation, it serves as a constraint for galaxy formation
and evolution models.


title: Evolution and nucleosynthesis of primordial low mass stars

abstract:
  We discuss in detail the evolutionary properties of low mass stars M< 1
M(Solar) having metallicity lower than Z=10^(-6) from the pre- main sequence up
to (almost) the end of the Asymptotic Giant Branch phase. We also discuss the
possibility that the large [C,N/Fe] observed on the surface of the most Iron
poor star presently known, HE0107-5240, may be attributed to the autopollution
induced by the penetration of the He convective shell into the H rich mantle
during the He core flash of a low mass, very low metallicity star. On the basis
of a quite detailed analysis, we conclude that the autopollution scenario
cannot be responsible for the observed chemical composition of HE0107-5240.


title: Multiwavelength scaling relations for nuclei of Seyfert galaxies

abstract:
  We analyze an X-ray flux-limited, complete sample of 93 AGN at z< 0.1,
selected from the ROSAT Bright Survey. Two thirds of the sample are Seyfert 1
galaxies (Sy1) and one third are Narrow-Line Seyfert 1 galaxies (NLSy1). We
have obtained optical images of all objects. By modeling the host galaxy and
the AGN central component we decompose the optical emission into nuclear, bulge
and disk components, respectively. We find that the nuclear optical luminosity,
thought to be associated with the accretion disk surrounding the active black
hole, correlates with the X-ray luminosity, the radio luminosity and the black
hole mass.


title: NLTE Spectral Analysis of Central Stars of PNe Interacting with the ISM

abstract:
  The analysis of Planetary Nebulae (PNe) provides a tool to investigate the
properties of their exciting central stars (CSPN) at the moment of the PN
ejection as well as on the properties of the ambient interstellar medium (ISM).
The spectral analysis of the CSPN is a prerequisite to calculate the ionizing
flux which is a crucial input for reliable PN modeling. In the framework of a
systematic study of PNe interacting with the ISM, we present preliminary
results of ongoing NLTE spectral analyses of ten of their CS based on new
optical medium-resolution spectra.


title: Detection of cool dust around the G2V star HD 107146

abstract:
  We report the detection of dust emission at sub-millimeter wavelengths from
HD 107146, a G2V star with an age estimated to lie between 80 and 200 Myr. The
emission is resolved at 450um with a size 300 AU x 210 AU. A fit to the
spectral energy distribution gives a dust temperature of 51 K and dust mass of
0.10 Earth masses. No excess emission above the photosphere was detected at
18um showing that there is very little warm dust and implying the presence of a
large inner hole, at least 31 AU (~ 1'') in radius, around the star. The
properties of this star-disk system are compared with similar observations of
other systems. We also discuss prospects for future observations that may be
able to determine whether the inner hole is maintained by the dynamical effect
of an unseen orbiting companion.


title: A 3D Monte Carlo Photoionization Code for Modeling Diffuse Ionized Gas

abstract:
  We have developed a three dimensional Monte Carlo photoionization code
tailored for the study of Galactic H II regions and the percolation of ionizing
photons in diffuse ionized gas. We describe the code, our calculation of
photoionization, heating & cooling, and the approximations we have employed for
the low density H II regions we wish to study. Our code gives results in
agreement with the Lexington H II region benchmarks. We show an example of a 2D
shadowed region and point out the very significant effect that diffuse
radiation produced by recombinations of helium has on the temperature within
the shadow.


title:
The Three-point Correlation Function of Galaxies Determined from the 2dF
  Galaxy Redshift Survey

abstract:
  In a detailed analysis of the three point correlation function (3PCF) for the
2dF Galaxy Redshift Survey we have accurately measured the 3PCF for galaxies of
different luminosity. The 3PCF amplitudes [$\Qsu$ or $\Qrpu$] of the galaxies
generally decrease with increasing triangle size and increase with the shape
parameter $v$, in qualitative agreement with the predictions for the clustering
of dark matter in popular hierarchical CDM models. The 2dFGRS results agree
well with the results of Jing & B\"orner for the Las Camapanas Redshift Survey
(LCRS), though the measurement accuracy is greatly improved in the present
study. The dependence of the 3PCF on luminosity is not significant, but there
seems to be a trend for the brightest galaxy sample to have a lower amplitude
than the fainter ones. Comparing the measured 3PCF amplitudes [$\Qsu$ or
$\Qrpu$] to the prediction of a WMAP concordance model, we find that the
measured values are consistently lower than the predicted ones for dark matter.
This is most pronounced for the brightest galaxies, for which about one-half of
the predicted $Q$ value provides a good description of $\Qrpu$ for the 2dFGRS
data. For a less luminous sample, the $Q$ values are also smaller than in the
dark matter model on small scales, but on scales larger than $s=8 \mpc$ and
$r_p=3.25 \mpc$ they reach the model values. We discuss implications for
current theories of galaxy formation.


title:
The high-energy galactic tau neutrino flux and its atmospheric
  background

abstract:
  We compare the tau neutrino flux arising from the galaxy and the earth
atmosphere for $10^{3} \leq E/{GeV} \leq 10^{11}$. The intrinsic and oscillated
tau neutrino fluxes from both sources are considered. We find that, for $E\geq
10^3$ GeV, the oscillated $\nu_{\tau}$ flux along the galactic plane dominates
over the maximal intrinsic atmospheric $\nu_{\tau}$ flux, i.e., the flux along
the horizontal direction. We also briefly comment on the prospects for
observing these high-energy tau neutrinos.


title: Evidence for grain growth in T Tauri disks

abstract:
  In this article we present the results from mid-infrared spectroscopy of a
sample of 14 T Tauri stars with silicate emission. The qualitative analysis of
the spectra reveals a correlation between the strength of the silicate feature
and its shape similar to the one which was found recently for the more massive
Herbig Ae/Be stars by van Boekel et al. (2003). The comparison with theoretical
spectra of amorphous olivine with different grain sizes suggests that this
correlation is indicating grain growth in the disks of T Tauri stars. Similar
mechanisms of grain processing appear to be effective in both groups of young
stars.


title:
A simple method of correcting magnitudes for the errors introduced by
  atmospheric refraction

abstract:
  We show that the errors due to atmospheric refraction are present in the
magnitudes determined with the Difference Images Analysis method. In case of
single, unblended stars the size of the effect agrees with the theoretical
prediction. But when the blending is strong, what is quite common in a dense
field, then the effect of atmospheric refraction can be strongly amplified to
the extend that some cases of apparently variable stars with largest amplitudes
of variations are solely due to refraction. We present a simple method of
correcting for this kind of errors.


title:
Exclusion limits on spin dependent WIMP-nucleon couplings from the
  SIMPLE experiment

abstract:
  The SIMPLE experiment is reanalyzed within the context of the WIMP model
independent framework of Tovey et. al.. The results are compared with those of
the UK NAIAD and NaF experiments as recently reported by the Tokyo group,
together with those of the latest UK NAIAD results in 2003, and further
constrain the allowed parameter space.


title:
Subaru Spectroscopy of the Interacting Type Ia Supernova SN 2002ic:
  Evidence of a Hydrogen-rich, Asymmetric Circumstellar Medium

abstract:
  Optical spectroscopy of the Type Ia supernova SN 2002ic obtained on 2003 June
27.6 UT, i.e., about 222 rest-frame days after explosion, is presented. Strong
H emission indicates an interaction between the expanding SN ejecta and an
H-rich circumstellar medium (CSM). The spectrum of SN 2002ic resembles those of
SNe 1997cy and 1999E. The three SNe also have similar luminosities, suggesting
that they are the same phenomenon and that the CSM is also similar. We propose
a new classification, Type IIa SNe, for these events. The observed line
profiles and line ratios are measured and discussed within the ejecta-CSM
interaction scenario. The emission in H Balmer, [O III], and He I lines, and in
permitted Fe II blends, resembles the spectra of the Type IIn SN 1987F and of
Seyfert 1 galaxies. A high-density, clumpy CSM is inferred. Strong, very broad
[Ca II]/Ca II and [O I]/O I missions imply that not all the outer SN ejecta
were decelerated in the interaction, suggesting that the CSM is aspherical.