title:
Discovery of Soft Spectral Component and Transient 22.7s Quasi Periodic
  Oscillations of SAX J2103.5+4545

abstract:
  XMM-Newton observed SAX J2103.5+4545 on January 6, 2003, while RXTE was
monitoring the source. Using RXTE-PCA dataset between December 3, 2002 and
January 29, 2003, the spin period and average spin-up rate during the
XMM-Newton observations were found to be $354.7940\pm0.0008$ s and
$(7.4\pm0.9)\times10^{-13}$Hz s$^{-1}$ respectively. In the power spectrum of
the 0.9-11 keV EPIC-PN lightcurve, we found quasi periodic oscillations around
0.044 Hz (22.7 s) with an rms fractional amplitude $\sim $6.6 %. We interpreted
this QPO feature as the Keplerian motion of inhomogenuities through the inner
disk. In the X-ray spectrum, in addition to the power law component with high
energy cutoff and $\sim6.4$ keV fluorescent iron emission line (Baykal et al.,
2002), we discovered a soft component consistent with a blackbody emission with
${\rm{kT}}\sim1.9$keV. The pulse phase spectroscopy of the source revealed that
the blackbody flux peaked at the peak of the pulse with an emission radius
$\sim 0.3$ km, suggesting the polar cap on the neutron star surface as the
source of blackbody emission. The flux of the iron emission line at $\sim 6.42$
keV was shown to peak at the off-pulse phase, supporting the idea that this
feature arises from fluorescent emission of the circumstellar material around
the neutron star rather than the hot region in the vicinity of the neutron star
polar cap.


title: Chaotic behavior of micro quasar GRS 1915+105

abstract:
  Black hole binaries are variable in timescales of rang from months to
milli-seconds. The origin of this variability is still not clear, it could be
due to the variation of external parameters, like mass accretion rate,
instabilities in the inner regions of the accretion flow etc. Important
constraints on these possibilities can be obtained from the study of the
non-linear behavior of fluctuations. We present a modified non-linear time
series analysis technique which optimizes the use of the available data and
computes the correlation dimension in a non-subjective manner. We apply this
technique to the X-ray light-curve of the black hole system, GRS 1915+105, to
show conclusively that at least for four of its twelve temporal classes, the
underlying mechanism is a low order chaotic one.


title: Acoustic Oscillations in Solar and Stellar Flaring Loops

abstract:
  Evolution of a coronal loop in response to an impulsive energy release is
numerically modelled. It is shown that the loop density evolution curves
exhibit quasi-periodic perturbations with the periods given approximately by
the ratio of the loop length to the average sound speed, associated with the
second standing harmonics of an acoustic wave. The density perturbations have a
maximum near the loop apex. The corresponding field-aligned flows have a node
near the apex. We suggest that the quasi-periodic pulsations with periods in
the range 10-300 s, frequently observed in flaring coronal loops in the radio,
visible light and X-ray bands, may be produced by the second standing harmonic
of the acoustic mode.


title: Chemical and Thermal History of the Intracluster Medium

abstract:
  Clusters of galaxies can be seen as giant astrophysical laboratories
enclosing matter in a large enough volume, so that the matter composition can
be taken as representing the composition of our Universe. X-ray observations
allow a very precise investigation of the physical properties of the
intracluster plasma allowing us to probe probe the cluster structure, determine
its total mass, and measure the baryon fraction in clusters and in the Universe
as a whole. We can determine the abundance of heavy elements from O to Ni which
originate from supernova explosions and draw from this important conclusions on
the history of star formation in the cluster galaxy population. From the
entropy structure of the intracluster medium we obtain constraints on the
energy release during early star bursts. With the observational capabilities of
the X-ray observatories XMM-Newton and Chandra this field of research is
rapidly evolving. In particular, first detailed observations of the
intracluster medium of the Virgo cluster around M87 have provided new insights.
The present contribution gives an account of the current implications of the
intracluster medium observations, but more importantly illustrates the
prospects of this research for the coming years.


title: Formation and evolution of S0 galaxies: a SAURON case study of NGC7332

abstract:
  We present SAURON integral-field observations of the S0 galaxy NGC7332.
Existing broad-band ground-based and HST photometry reveals a double disk
structure and a boxy bulge interpreted as a bar viewed close to edge-on. The
SAURON two-dimensional stellar kinematic maps confirm the existence of the bar
and inner disk but also uncover the presence of a cold counter-rotating stellar
component within the central 250 pc. The Hbeta and [OIII] emission line maps
show that the ionised gas has a complex morphology and kinematics, including
both a component counter-rotating with respect to the stars and a fainter
co-rotating one. Analysis of the absorption line-strength maps show that
NGC7332 is young everywhere. The presence of a large-scale bar can explain most
of those properties, but the fact that we see a significant amount of unsettled
gas, together with a few peculiar features in the maps, suggest that NGC7332 is
still evolving. Interactions as well as bar-driven processes must thus have
played an important role in the formation and evolution of NGC7332, and
presumably of S0 galaxies in general.


title:
The XMM-Newton and BeppoSAX view of the Ultra Luminous Infrared Galaxy
  MKN 231

abstract:
  We discuss XMM-Newton and BeppoSAX observations of MKN 231, the
lowest-redshift Broad Absorption Line (BAL) QSO known so far and one of the
best-studied Ultra Luminous Infrared Galaxies. By combining the XMM-Newton
spectral resolution and the high-energy bandpass of BeppoSAX we have been able
to study in more detail than previously possible its 0.2--50 keV spectral
properties. The BeppoSAX PDS data unveiled, for the first time, a highly
absorbed ($N_H\sim 2\times 10^{24}$cm$^{-2}$) power-law component. We find
that: a) below 10 keV we are seeing only reprocessed radiation through
reflection and/or scattering; b) the intrinsic 2-10 keV luminosity of MKN 231
is $1^{+1.0}_{-0.5} \times 10^{44}$ ergs s$^{-1}$, i.e. more than an order of
magnitude greater than previous measurements; c) the starburst activity
significantly contributes to the soft ($E<2$ keV) X-ray emission.


title:
On the estimation of gravity-induced non-Gaussianities from weak lensing
  surveys

abstract:
  We study various measures of weak lensing distortions in future surveys,
taking into account the noise arising from the finite survey size and the
intrinsic ellipticity of galaxies. We also consider a realistic redshift
distribution of the sources, as expected for the SNAP mission. We focus on the
low order moments and the full distribution function (pdf) of the aperture-mass
$\Map$ and of the smoothed shear component $\gammais$. We also propose new
unbiased estimators for low-order cumulants which have less scatter than the
usual estimators of non-Gaussianity based on the moments themselves. Then,
using an analytical model which has already been seen to provide a good
description of weak gravitational lensing through comparison against numerical
simulations, we study the statistical measures which can be extracted from
future surveys like the SNAP experiment. We recover the fact that at small
angular scales ($1'<\theta_s<10'$) the variance can be extracted with a few
percent level accuracy. Non-Gaussianity can also be measured from the skewness
of the aperture-mass (at a 10% level) while the shear kurtosis is more noisy
and cannot be easily measured beyond 6'. On the other hand, we find that the
pdf of the estimator associated with the aperture-mass can be distinguished
both from the Gaussian and the Edgeworth expansion and could provide useful
constraints, while this appears to be difficult to realize with the shear
component. Finally, we investigate various survey strategies and the
possibility to perform a redshift binning of the sample.


title: Unified dark energy models : a phenomenological approach

abstract:
  A phenomenological approach is proposed to the problem of universe
accelerated expansion and of the dark energy nature. A general class of models
is introduced whose energy density depends on the redshift $z$ in such a way
that a smooth transition among the three main phases of the universe evolution
(radiation era, matter domination, asymptotical de Sitter state) is naturally
achieved. We use the estimated age of the universe, the Hubble diagram of Type
Ia Supernovae and the angular size - redshift relation for compact and
ultracompact radio structures to test whether the model is in agreement with
astrophysical observation and to constrain its main parameters. Although
phenomenologically motivated, the model may be straightforwardly interpreted as
a two fluids scenario in which the quintessence is generated by a suitably
chosen scalar field potential. On the other hand, the same model may also be
read in the context of unified dark energy models or in the framework of
modified Friedmann equation theories.


title: A Chandra Study of the Core of the Nearby Cluster Abell 576

abstract:
  We present data from a Chandra observation of the nearby cluster of galaxies
Abell 576. The core of the cluster shows a significant departure from dynamical
equilibrium. We show that this core gas is most likely the remnant of a merging
subcluster, which has been stripped of much of its gas, depositing a stream of
gas behind it in the main cluster. The unstripped remnant of the subcluster is
characterized by a different temperature, density and metalicity than that of
the surrounding main cluster, suggesting its distinct origin. Continual
dissipation of the kinetic energy of this minor merger may be sufficient to
counteract most cooling in the main cluster over the lifetime of the merger
event.


title: The Impact of AMR in Numerical Astrophysics and Cosmology

abstract:
  I survey the use and impact of adaptive mesh refinement (AMR) simulations in
numerical astrophysics and cosmology. Two basic techniques are in use to extend
the dynamic range of Eulerian grid simulations in multi-dimensions: cell
refinement, and patch refinement, otherwise known as block-structured adaptive
mesh refinement (SAMR). In this survey, no attempt is made to assess the
relative merits of these two approaches. Rather, the discussion focuses on how
AMR is being used and how AMR is making a scientific impact in a diverse set of
fields from space physics to the cosmology of the early universe. The increased
adoption of AMR techniques in the past decade is driven in part by the public
availability of AMR codes and frameworks. I provide a partial list of resources
for those interested in learning more about AMR simulations.


title: 1E1207.4-5209 - a Unique Object

abstract:
  The discovery of deep spectral features in the X-ray spectrum of
1E1207.4-5209 focussed the attention of the astronomical community on this
radio-quiet NS, making it the most intensively observed INS ever. The harvest
of X-ray photons, collected mainly by XMM-Newton, unveiled a number of unique
characteristics, raising questions on this source very nature.


title: Geminga: a tale of two tails, and much more

abstract:
  We report on the deep (100 ksec) XMM-Newton/EPIC observation of the field of
the Geminga pulsar. The unprecedented throughput of the instrument allowed to
detect two elongated parallel X-ray tails trailing the neutron star. They are
aligned with the object's supersonic motion, extend for ~2', and have a
nonthermal spectrum produced by electron-synchrotron emission in the bow shock
between the pulsar wind and the surrounding medium. Electron lifetime against
synchrotron cooling matches the source transit time over the X-ray features'
length. Such an X-ray detection of a pulsar bow shock allows us to gauge the
pulsar electron injection energy and the shock magnetic field while
constraining the angle of Geminga's motion and the local matter density. We
give also preliminary results on the timing and spectral analysis of the
\~63,000 photons collected from the neutron star.


title: The EPIC/MOS view of the 2-8 keV Cosmic X-ray Background Spectrum

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, with 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% (1 sigma), suggesting the
existence of a new population of faint sources, largely undetected within the
current sensitivity limits of the deepest X-ray surveys.


title: The Atacama Cosmology Telescope

abstract:
  The Atacama Cosmology Telescope (ACT) project is described. This
multi-institution collaboration aims to produce arcminute-resolution and
micro-Kelvin sensitivity maps of the microwave background temperature over 200
square degrees of the sky in three frequency bands. We give a brief overview of
the scientific motivations for such a map, followed by a design outline of our
six-meter custom telescope, an overview of our proposed bolometer array
detector technology, and site considerations and scan strategy. We also
describe associated optical and X-ray galaxy cluster surveys.


title:
The Evolution of the Ultraluminous Infrared Galaxy Population from
  Redshift 0 to 1.5

abstract:
  We use redshift observations of two deep 1.4GHz fields to probe the evolution
of the bright end of the radio galaxy luminosity function to z=1.5. We show
that the number of galaxies with radio power that would correspond locally to
an ultraluminous infrared galaxy (ULIG) evolves rapidly over this redshift
range. The optical spectra and X-ray luminosities are used to refine this
result by separating the sources with clear active galactic nucleus (AGN)
signatures from those that may be dominated by star formation. Both populations
show extremely rapid evolution over this redshift range. We find that the
number of sources with ULIG radio power and no clear AGN signatures evolves as
(1+z)^(7).


title: Chandra Observations of X-ray Weak Narrow-Line Seyfert 1 Galaxies

abstract:
  We present Chandra observations of 17 optically-selected, X-ray weak
narrow-line Seyfert 1 (NLS1) galaxies. These objects were optically identified
by Williams et al. (2002) in the Sloan Digital Sky Survey Early Data Release,
but were not found in the ROSAT All-Sky Survey (RASS) despite having optical
properties similar to RASS-detected NLS1s. All objects in this sample were
detected by Chandra and exhibit a range of 0.5-2 keV photon indices
Gamma=1.1-3.4. One object was not detected in the soft band, but has a best-fit
Gamma=0.25 over the full 0.5-8 keV range. These photon indices extend to values
far below what are normally observed in NLS1s. A composite X-ray spectrum of
the hardest objects in this sample does not show any signs of absorption,
although the data do not prohibit one or two of the objects from being highly
absorbed. We also find a strong correlation between Gamma and L_1keV; this may
be due to differences in L_bol/L_Edd among the NLS1s in this sample. Such
variations are seemingly in conflict with the current paradigm that NLS1s
accrete near the Eddington limit. Most importantly, this sample shows that
strong, ultrasoft X-ray emission is not a universal characteristic of NLS1s; in
fact, a substantial number may exhibit weak and/or low-Gamma X-ray emission.


title: On the environmental dependence of halo formation

abstract:
  A generic prediction of hierarchical gravitational clustering models is that
the distribution of halo formation times should depend relatively strongly on
halo mass, massive haloes forming more recently, and depend only weakly, if at
all, on the large scale environment of the haloes. We present a novel test of
this assumption which uses a statistic that proves to be particularly
well-suited to detecting and quantifying weak correlations with environment. We
find that close pairs of haloes form at slightly higher redshifts than do more
widely separated halo pairs, suggesting that haloes in dense regions form at
slightly earlier times than do haloes of the same mass in less dense regions.
The environmental trends we find are useful for models which relate the
properties of galaxies to the formation histories of the haloes which surround
them.


title:
The Far-Ultraviolet Spectra of TW Hya. II. Models of H2 Fluorescence in
  a Disk

abstract:
  We measure the temperature of warm gas at planet-forming radii in the disk
around the classical T Tauri star (CTTS) TW Hya by modelling the H2
fluorescence observed in HST/STIS and FUSE spectra. Strong Ly-alpha emission
irradiates a warm disk surface within 2 AU of the central star and pumps
certain excited levels of H2. We simulate a 1D plane-parallel atmosphere to
estimate fluxes for the 140 observed H2 emission lines and to reconstruct the
Ly-alpha emission profile incident upon the warm H2. The excitation of H2 can
be determined from relative line strengths by measuring self-absorption in
lines with low-energy lower levels, or by reconstructing the Ly-alpha profile
incident upon the warm H2 using the total flux from a single upper level and
the opacity in the pumping transition. Based on those diagnostics, we estimate
that the warm disk surface has a column density of log
N(H2)=18.5^{+1.2}_{-0.8}, a temperature T=2500^{+700}_{-500} K, and a filling
factor of H2, as seen by the source of Ly-alpha emission, of 0.25\pm0.08 (all
2-sigma error bars). TW Hya produces approximately 10^{-3} L_\odot in the FUV,
about 85% of which is in the Ly-alpha emission line. From the H I absorption
observed in the Ly-alpha emission, we infer that dust extinction in our line of
sight to TW Hya is negligible.


title: Free-Free Emission at Low Radio Frequencies

abstract:
  We discuss free-free radio emission from ionized gas in the intergalactic
medium. Because the emissivity is proportional to the square of the electron
density, the mean background is strongly sensitive to the spatial clumping of
free electrons. Using several existing models for the clumping of ionized gas,
we find that the expected free-free distortion to the cosmic microwave
background (CMB) blackbody spectrum is at a level detectable with upcoming
experiments such as the Absolute Radiometer for Cosmology, Astrophysics, and
Diffuse Emission (ARCADE). However, the dominant contribution to the distortion
comes from clumpy gas at z < 3, and the integrated signal does not strongly
constrain the epoch of reionization. In addition to the mean emission, we
consider spatial fluctuations in the free-free background and the extent to
which these anisotropies confuse the search for fluctuations in 21 cm line
emission from neutral hydrogen during and prior to reionization. This
background is smooth in frequency space and hence can be removed through
frequency differencing, but only so long as the 21 cm signal and the free-free
emission are uncorrelated. We show that, because the free-free background is
generated primarily at low redshifts, the cross-correlation between the two
fields is smaller than a few percent. Thus, multifrequency cleaning should be
an effective way to eliminate the free-free confusion.


title:
On the Afterglow of the X-Ray Flash of July 23 2003: Photometric
  evidence for an off-axis Gamma-Ray Burst with an associated Supernova?

abstract:
  We present optical and near-infrared follow-up observations of the X-Ray
Flash (XRF) of July 23 2003. Our observations in the R-band cover the temporal
range from 4.2 h to 64 days after the high energy event. We also present the
results of multicolor imaging extending to the K-band on three epochs. The
lightcurve of the R-band afterglow the first week after the burst is similar to
the lightcurve for long duration Gamma-Ray Bursts (GRBs), i.e., a broken
power-law with a late time slope of alpha=-2.0 (F_nu propto t^alpha).
Furthermore, the spectral energy distribution (SED) has a power-law (F_nu
propto nu^beta) shape with slope beta=-1.0. However, the decay slope at t<1 day
is shallow, consistent with zero. This is in qualitative agreement with the
prediction that XRFs are off-axis classical GRBs. After the first week there is
a strong bump in the lightcurve, which peaks at around 16 days. The SED after
the peak becomes significantly redder. We discuss the possible interpretations
of this bump, and conclude that an underlying supernova is the most likely
explanation since no other model appears consistent with the evolution of the
SED. Finally, we present deep spectroscopy of the burst both in the afterglow
and in the bump phase. A firm upper limit of z=2.3 is placed on the redshift of
XRF030723 from the lack of Ly-alpha forest lines in the spectrum of the
afterglow. The lack of significant absorption and emission lines in either of
the two spectra excludes a spectroscopic redshift determination.


title: Photoevaporation of Circumstellar Disks around Young Stars

abstract:
  We examine the ability of photoevaporative disk winds to explain the
low-velocity components observed in the forbidden line spectra of low-mass T
Tauri stars. Using the analytic model of Shu, Johnstone, & Hollenbach (1993)
and Hollenbach et al. (1994) as a basis, we examine the characteristics of
photoevaporative outflows with hydrodynamic simulations. General results from
the simulations agree well with the analytic predictions, although some small
differences are present. Most importantly, the flow of material from the disk
surface develops at smaller radii than in the analytic approximations and the
flow-velocity from the disk surface is only one-third the sound speed. A
detailed presentation of observational consequences of the model is given,
including predicted line widths, blue-shifts, and integrated luminosities of
observable sulfur and nitrogen emission lines. We demonstrate that these
predictions are in agreement with current observational data on the
low-velocity forbidden line emission of ionized species from T Tauri stars.
This is in contrast with magnetic wind models, which systematically
under-predict these forbidden line luminosities. However, the present model
cannot easily account for the luminosities of neutral oxygen lines in T Tauri
stars.


title:
CAIRNS: The Cluster And Infall Region Nearby Survey II. Environmental
  Dependence of Infrared Mass-to-Light Ratios

abstract:
  CAIRNS (Cluster And Infall Region Nearby Survey) is a spectroscopic survey of
the infall regions surrounding nine nearby rich clusters of galaxies. In Paper
I, we used redshifts within $\sim 10\Mpc$ of the centers of the clusters to
determine the mass profiles of the clusters based on the phase space
distribution of the galaxies. Here, we use 2MASS photometry and an additional
\ncziinew redshifts to investigate the environmental dependence of
near-infrared mass-to-light ratios. In the virial regions, the halo occupation
function is non-linear; the number of bright galaxies per halo increases more
slowly than the mass of the halo. On larger scales, the light contained in
galaxies is less clustered than the mass in rich clusters. Specifically, the
mass-to-light ratio inside the virial radius is a factor of $1.8\pm0.3$ larger
than that outside the virial radius. This difference could result from changing
fractions of baryonic to total matter or from variations in the efficiency of
galaxy formation or disruption with environment. The average mass-to-light
ratio $M/L_K = 53\pm 5 h$ implies $\Omega_m = 0.18\pm 0.03$ (statistical) using
the luminosity density based on 2dFGRS data. These results are difficult to
reconcile with independent methods which suggest higher $\Omega_m$. Reconciling
these values by invoking bias requires that the typical value of $M/L_K$
changes significantly at densities of $\lesssim3\rho_c$.


title: Diffuse Gamma Rays: Galactic and Extragalactic Diffuse Emission

abstract:
  "Diffuse" gamma rays consist of several components: truly diffuse emission
from the interstellar medium, the extragalactic background, whose origin is not
firmly established yet, and the contribution from unresolved and faint Galactic
point sources. One approach to unravel these components is to study the diffuse
emission from the interstellar medium, which traces the interactions of high
energy particles with interstellar gas and radiation fields. Because of its
origin such emission is potentially able to reveal much about the sources and
propagation of cosmic rays. The extragalactic background, if reliably
determined, can be used in cosmological and blazar studies. Studying the
derived "average" spectrum of faint Galactic sources may be able to give a clue
to the nature of the emitting objects.


title:
The angular size of the Cepheid L Car: a comparison of the
  interferometric and surface brightness techniques

abstract:
  Recent interferometric observations of the brightest and angularly largest
classical Cepheid, L Carinae, with ESO's VLT Interferometer (VLTI) have
resolved with high precision the variation of its angular diameter with phase.
We compare the measured angular diameter curve to the one we derive by an
application of the Baade-Wesselink type infrared surface brightness technique,
and find a near-perfect agreement between the two curves. The mean angular
diameters of L Car from the two techniques agree very well within their total
error bars (1.5 %), as do the derived distances (4 %). This result is an
indication that the calibration of the surface brightness relations used in the
distance determination of far away Cepheids is not affected by large biases.


title: Non-extensive statistics and the stellar polytrope index

abstract:
  We use physical constrains imposed from the H-Theorem and from the negative
nature of the heat capacity of self-gravitating thermodynamically isolated
systems to investigate some possible limits on the stellar polytrope index $n$
within the domain of a classical non-extensive kinetic theory.


title: On the Evolutionary State of the Components of the YLW 15 Binary System

abstract:
  We report centimeter continuum observations with the VLA and the VLBA as well
as mid-infrared observations with COMICS/SUBARU toward the components of the
YLW 15 very young binary system, VLA 1 and VLA 2. The centimeter emission of
the two components traces partially thick free-free emission, likely due to
collimated, ionized winds. VLA 1 is an embedded protostar, undetected in the
near-IR, and possibly in the Class 0 to Class I transition and powering a
Herbig-Haro outflow. Its mid-IR emission appears slightly resolved with a
diameter of ~16 AU, possibly tracing circumstellar material from both the
envelope and the disk. VLA 2 is a typical Class I object, unresolved in the
mid-IR, and is the responsible of the strong X-ray emission associated with YLW
15. The expected centimeter ''peri-stellar'' emission associated with the X-ray
emission is not detected with the VLBA at 6 cm likely due to the high optical
depth of the free-free emission. Strikingly, the near to mid-IR properties of
YLW 15 suggest that VLA 1 is a more embedded YSO, or alternatively, less
luminous than VLA 2, whereas orbital proper motions of this binary system
indicate that VLA 1 is more massive than VLA 2. This result is apparently
against the expected evolutionary scenario, where one expects that the more
massive YSO in a binary system is the more evolved and luminous YSO. Finally,
the nearby source YLW 16A is detected with the VLA, its position coincides with
reported near-IR and X-ray sources.


title:
Chandra Observations of the "Dark" Moon and Geocoronal Solar-Wind Charge
  Transfer

abstract:
  We have analyzed data from two sets of calibration observations of the Moon
made by the Chandra X-ray Observatory. In addition to obtaining a spectrum of
the bright side that shows several distinct fluorescence lines, we also clearly
detect time-variable soft X-ray emission, primarily O VII Ka and O VIII Lya,
when viewing the optically dark side. The apparent dark-side brightness varied
by at least an order of magnitude, up to 2x10^-6 phot/s/arcmin^2/cm^2 between
500 and 900 eV, which is comparable to the typical 3/4-keV-band background
emission measured in the ROSAT All-Sky Survey. The spectrum is also very
similar to background spectra recorded by Chandra in low or moderate-brightness
regions of the sky. Over a decade ago, ROSAT also detected soft X-rays from the
dark side of the Moon, which were tentatively ascribed to continuum emission
from energetic solar wind electrons impacting the lunar surface. The Chandra
observations, however, with their better spectral resolution, combined with
contemporaneous measurements of solar-wind parameters, strongly favor charge
transfer between highly charged solar-wind ions and neutral hydrogen in the
Earth's geocorona as the mechanism for this emission. We present a theoretical
model of geocoronal emission and show that predicted spectra and intensities
match the Chandra observations very well. We also model the closely related
process of heliospheric charge transfer and estimate that the total charge
transfer flux observed from Earth amounts to a significant fraction of the soft
X-ray background, particularly in the ROSAT 3/4-keV band.


title: Shock-induced star formation in a model of the Mice

abstract:
  Star formation plays an important role in the fate of interacting galaxies.
To date, most galactic simulations including star formation have used a
density-dependent star formation rule designed to approximate a Schmidt law.
Here, I present a new star formation rule which is governed by the local rate
of energy dissipation in shocks. The new and old rules are compared using
self-consistent simulations of NGC 4676; shock-induced star formation provides
a better match to the observations of this system.


title: On the mixing rules for interstellar inhomogeneous grains

abstract:
  We present the computation of effective refractive coefficients for
inhomogeneous two-component grains with 3 kinds of inclusions with ${\rm
m_{incl}=3.0+4.0i, 2.0+1.0i, 2.5+0.0001i}$ and a matrix with ${\rm
m_m=1.33+0.01i}$ for 11 volume fractions of inclusions from 0% to 50% and
wavelengths ${\rm\lambda}$=0.5, 1.0, 2.0 and 5.0 ${\rm \mu m}$. The
coefficients of extinction for these grains have been computed using a discrete
dipole approximation (DDA). Computation of the extinction by the same method
for grains composed of a matrix material with randomly embedded inclusions has
been carried out for different volume fractions of inclusions. A comparison of
extinction coefficients obtained for both models of grain materials allows to
choose the best mixing rule for a mixture. In cases of inclusions with ${\rm
m_{incl}}$=2.0+1.0i and 2.5+0.0001i the best fit for the whole wavelengths
range and volume fractions of inclusions from 0 to 50% has been obtained for
Lichtenecker mixing rule. In case of ${\rm m_{incl}=3.0+4.0i}$ the fit for the
whole wavelength range and volume fractions of inclusions from 0 to 50% is not
very significant but the best has been obtained for Hanai rule. For volume
fractions of inclusion from 0 to 15% a very good fit has been obtained for the
whole wavelength range for Rayleigh and Maxwell-Garnett mixing rules.


title:
Halpha Kinematics of Tidal Tails in Interacting Systems: Projection
  Effects and Dark Matter in TDGs

abstract:
  Several interacting systems exhibit at the tip of their long tidal tails
massive condensations of atomic hydrogen, which may be the progenitors of Tidal
Dwarf Galaxies. Because, quite often, these tails are observed edge-on,
projection effects have been claimed to account for the large HI column
densities measured there. Here we show that determining the velocity field all
along the tidal features, one may disentangle projection effects along the line
of view from real bound structures. Due to its large field of view, high
spectral and 2D spatial resolutions, Fabry-Perot observations of the ionized
gas are well adapted to detect a kinematical signature of either streaming
motions along a bent tidal tail or of infalling/rotating material associated
with a forming TDG. Spectroscopic observations also allow to measure the
dynamical masses of the TDGs that are already relaxed and check their dark
matter content.


title: Synchrotron emission from circumstellar disks around massive stars

abstract:
  We argue that the interaction of stellar wind with the surface of a
circumstellar accretion (or protoplanetary) disk can result in the acceleration
of relativistic electrons in an external layer of the disk, and produce
synchrotron radiation. Conservative estimates give a total synchrotron
luminosity $L_s\sim 10^{-5}\lsun$ for a central star with $\dot M=10^{-6}\msun$
yr$^{-1}$, comparable with the value observed around the TW object in the
W3(OH) region.


title:
Identifying old Tidal Dwarf Galaxies in Simulations and in the Nearby
  Universe

abstract:
  Most Tidal Dwarf Galaxies (TDGs) so-far discussed in the literature may be
considered as young ones or even newborns, as they are still physically linked
to their parent galaxies by an umbilical cord: the tidal tail at the tip of
which they are usually observed. Old Tidal Dwarf Galaxies, completely detached
from their progenitors, are still to be found. Using N--body numerical
simulations, we have shown that tidal objects as massive as 10^9 solar masses
may be formed in interacting systems and survive for more than one Gyr. Old
TDGs should hence exist in the Universe. They may be identified looking at a
peculiarity of their "genetic identity card": a relatively high abundance in
heavy elements, inherited from their parent galaxies. Finally, using this
technique, we revisit the dwarf galaxies in the local Universe trying to find
arguments pro and con a tidal origin.


title: Charged Polytropic Stars and a Generalization of Lane-Emden Equation

abstract:
  In this paper we will discuss charged stars with polytropic equation of
state, where we will try to derive an equation analogous to the Lane-Emden
equation. We will assume that these stars are spherically symmetric, and the
electric field have only the radial component. First we will review the field
equations for such stars and then we will proceed with the analog of the
Lane-Emden equation for a polytropic Newtonian fluid and their relativistic
equivalent. These kind of equations are very interesting because they transform
all the structure equations of the stars in a group of differential equations
which are much more simple to solve than the source equations. These equations
can be solved numerically for some boundary conditions and for some initial
parameters. For this we will assume that the pressure caused by the electric
field obeys a polytropic equation of state too.


title: Primordial star formation triggered by UV photons from UHECR

abstract:
  The presence of ultra-high energy cosmic rays in the universe in the
pre-ionization epoch enhances significantly H$_2$ kinetics in virialized halos.
It results in more efficient radiative cooling and decreases the lower mass
limit of the first star-forming systems. Consequently, the fraction of baryons
contained in the first luminous objects and their contribution to the
reionization of the universe can significantly increase in comparison with the
standard scenario.


title:
FALCON: a concept to extend adaptive optics corrections to cosmological
  fields

abstract:
  FALCON is an original concept for a next generation spectrograph at ESO VLT
or at future ELTs. It is a spectrograph including multiple small integral field
units (IFUs) which can be deployed within a large field of view such as that of
VLT/GIRAFFE. In FALCON, each IFU features an adaptive optics correction using
off-axis natural reference stars in order to combine, in the 0.8-1.8 \mu m
wavelength range, spatial and spectral resolutions (0.1-0.15 arcsec and
R=10000+/-5000). These conditions are ideally suited for distant galaxy
studies, which should be done within fields of view larger than the galaxy
clustering scales (4-9 Mpc), i.e. foV > 100 arcmin2. Instead of compensating
the whole field, the adaptive correction will be performed locally on each IFU.
This implies to use small miniaturized devices both for adaptive optics
correction and wavefront sensing. Applications to high latitude fields imply to
use atmospheric tomography because the stars required for wavefront sensing
will be in most of the cases far outside the isoplanatic patch.


title:
Constraints in the circumstellar density distribution of massive Young
  Stellar Objects

abstract:
  We use a Monte Carlo code to generate synthetic near-IR reflection nebulae
that resemble those (normally associated with a bipolar outflow cavity) seen
towards massive young stellar objects (YSOs). The 2D axi-symmetric calculations
use an analytic expression for a flattened infalling rotating envelope with a
bipolar cavity representing an outflow. We are interested in which aspects of
the circumstellar density distribution can be constrained by servations of
these reflection nebulae. We therefore keep the line of sight optical depth
constant in the model grid, as this is often constrained independently by
observations. It is found that envelopes with density distributions
corresponding to mass infall rates of ~ 1E-4 M_sun/yr (for an envelope radius
of 4700 AU) seen at an inclination angle of ~ 45 deg approximately reproduce
the morphology and extension of the sub-arcsecond nebulae observed in massive
YSOs. Based on the flux ratio between the approaching and receding lobe of the
nebula, we can constrain the system inclination angle. The cavity opening angle
is well constrained from the nebula opening angle. Our simulations indicate
that to constrain the outflow cavity shape and the degree of flattening in the
envelope, near-IR imaging with higher resolution and dynamic range than speckle
imaging in 4m-class telescopes is needed. The radiative transfer code is also
used to simulate the near-IR sub-arcsecond nebula seen in Mon R2 IRS3. We find
indications of a shallower opacity law in this massive YSO than in the
interstellar medium, or possibly a sharp drop in the envelope density
distribution at distances of ~ 1000 AU from the illuminating source.


title: Stellar Populations of a Sample of Tidal Dwarf Galaxies

abstract:
  We investigate the stellar populations of a sample of Tidal Dwarf Galaxies,
combining observations and evolutionary synthesis models to try and reveal
their formation mechanism. On optical images we select a first sample of TDGs
for which optical spectroscopy is used to measure metallicities and velocity
structure. Finally, we estimate ages, burst strengths, and stellar masses from
near-infrared imaging in comparison with a dedicated grid of evolutionary
synthesis models, to assess if Tidal Dwarfs are formed out of collapsing gas
clouds or by an accumulation of old stars from the parent galaxy or by a
combination of both.


title: M87 as a misaligned Synchrotron-Proton Blazar

abstract:
  The giant radio galaxy M87 is usually classified as a Fanaroff-Riley class I
source, suggesting that M87 is a mis-aligned BL Lac object. Its unresolved
nuclear region emits strong non-thermal emission from radio to X-rays which has
been interpreted as synchrotron radiation. In an earlier paper we predicted M87
as a source of detectable gamma ray emission in the context of the hadronic
Synchrotron-Proton Blazar (SPB) model. The subsequent tentative detection of
TeV energy photons by the HEGRA-telescope array would, if confirmed, make it
the first radio galaxy to be detected at TeV-energies. We discuss the emission
from the unresolved nuclear region of M87 in the context of the SPB model, and
give examples of possible model representations of its non-simultaneous
spectral energy distribution. The low-energy component can be explained as
synchrotron radiation by a primary relativistic electron population that is
injected together with energetic protons into a highly magnetized emission
region. We find that the gamma-ray power output is dominated either by
mu/pi-synchrotron or proton synchrotron radiation depending on whether the
primary electron synchrotron component peaks at low or high energies,
respectively. The predicted gamma-ray luminosity peaks at around 100 GeV at a
level comparable to that of the low-energy hump, and this makes M87 a promising
candidate source for the newly-commissioned high-sensitivity low-threshold
Cherenkov telescopes H.E.S.S., VERITAS, MAGIC and CANGAROO III. (abridged)


title:
UV and FIR selected samples of galaxies in the local Universe. Dust
  extinction and star formation rates

abstract:
  We have built two samples of galaxies selected at 0.2micron (hereafter UV)
and 60micron (hereafter FIR) covering a sky area of 35.36 deg^2. The UV
selected sample contains 25 galaxies brighter than AB_0.2=17mag. All of them,
but one elliptical, are detected at 60micron with a flux density larger or
equal to 0.2Jy. The UV counts are significantly lower than the euclidean
extrapolation towards brighter fluxes of previous determinations. The FIR
selected sample contains 42 galaxies brighter than f_60=0.6Jy. Excepting four
galaxies, all of them have a UV counterpart at the limiting magnitude
AB_0.2=20.3mag. The mean extinction derived from the analysis of the FIR to UV
flux ratio is ~1mag for the UV selected sample and ~2mag for the FIR selected
one. For each sample we compare several indicators of the recent star formation
rate (SFR) based on the FIR and/or the UV emissions and we find linear
relationships with slopes close to unity, meaning that no trend with the SFR
exists when converting between each other. Various absolute calibrations for
both samples are discussed in this paper. A positive correlation between
extinction and SFR is found when both samples are considered together although
with a considerable scatter. A similar result is obtained when using the SFR
normalized to the optical surface of the galaxies.


title:
Radiative Hydrodynamic Modeling of the Bastille-Day Flare (14 July,
  2000): I. Numerical Simulations

abstract:
  A 1-D loop radiative hydrodynamic model that incorporates the effects of
gravitational stratification, heat conduction, radiative losses, external heat
input, presence of helium, and Braginskii viscosity is used to simulate
elementary flare loops. The physical parameters for the input are taken from
observations of the Bastille-Day flare of 2000 July 14. The present analysis
shows that: (a) The obtained maximum values of the electron density can be
considerably higher (4.2 X 10^{11} cm^{-3} or more) in the case of footpoint
heating than in the case of apex heating (2.5 X 10^{11} cm^{-3}). (b) The
average cooling time after the flare peak takes less time in the case of
footpoint heating than in the case of apex heating. (c) The peak apex
temperatures are significantly lower (by about 10 MK) for the case of footpoint
heating than for apex heating (for the same average loop temperature of about
30 MK). This characteristic allows us to discriminate between different heating
positioning. (d) In both cases (of apex and footpoint heating), the maximum
obtained apex temperature T^{max} is practically independent of the heating
duration sigma_{t}, but scales directly with the heating rate E_{H0}. (e) The
maximum obtained densities at the loop apex, n_e^{max}, increase with the
heating rate E_{H0} and heating duration sigma_{t} for both footpoint and apex
heating. In Paper II we will use the outputs of these hydrodynamic simulations,
which cover a wide range of the parameter space of heating rates and durations,
as an input for forward-fitting of the multi-loop arcade of the Bastille-day
flare. KEYWORDS: Sun: Flares -- Sun: Activity -- Sun: Corona


title: Flare Generated Acoustic Oscillations in Solar and Stellar Coronal Loops

abstract:
  Low-frequency longitudinal oscillations of a flaring coronal loop are studied
numerically. In the recent work of Nakariakov et al., Astron. and Astrophys.,
414, L25-L28 (2004) it has been shown that the time dependences of density and
velocity in a flaring loop contain well-pronounced quasi-harmonic oscillations
associated with a 2nd harmonic of a standing slow magnetoacoustic wave. In this
work we investigate physical nature of these oscillations in greater detail,
namely, we study their spectrum (using periodogram technique) and how does heat
positioning affects the mode excitation. We found that excitation of such
oscillations practically independent of the positioning of the heat deposition
in the loop. Because of the change of the background temperature and density,
the phase shift between the density and velocity perturbations is not exactly
equal to the quarter of the period, it varies along the loop and is time
dependent, especially in the case of one footpoint (asymmetric) heating.
  KEYWORDS -- Sun: flares -- Sun: oscillations -- Sun: Corona -- Stars: flare
-- Stars: oscillations -- Stars: coronae


title:
HI Fluctuations at Large Redshifts: III - Simulating the Signal Expected
  at GMRT

abstract:
  We simulate the distribution of neutral hydrogen (HI) at the redshifts z=1.3
and 3.4 using a cosmological N-body simulation along with a prescription for
assigning HI masses to the particles. The HI is distributed in clouds whose
properties are consistent with those of the damped Lyman-\alpha absorption
systems (DLAs) seen in quasar spectra. The clustering properties of these
clouds are identical to those of the dark matter. We use this to simulate the
redshifted HI emission expected at 610 MHz and 325 MHz, two of the observing
bands a the GMRT. These are used to predict the correlations expected between
the complex visibilities measured at different baselines and frequencies in
radio-interferometric observations with the GMRT. The visibility correlations
directly probe the power spectrum of HI fluctuations at the epoch when the HI
emission originated, and this holds the possibility of using HI observations to
study large-scale structures at high z.


title: What is the SUSY mass scale?

abstract:
  The energy, or mass scale M_SUSY, of the supersymmetry (SUSY) phase
transition is, as yet, unknown. If it is very high (i.e., ~ 10^3 GeV),
terrestrial accelerators will not be able to measure it. We determine M_SUSY
here by combining theory with the cosmic microwave background (CMB) data.
Starobinsky suggested an inflationary cosmological scenario in which inflation
is driven by quantum corrections to the vacuum Einstein's equation. The
modified Starobinsky model (MSM) is a natural extension of this. In the MSM,
the quantum corrections are the quantum fluctuations of the supersymetric
(SUSY) particles, whose particle content creates inflation and whose masses
terminate it. Since the MSM is difficult to solve until the end of the
inflation period, we assume here that an effective inflaton potential (EIP)
that reproduces the time dependence of the cosmological scale factor of the MSM
can be used to make predictions for the MSM. We predict the SUSY mass scale to
be M_SUSY ~ 10^15 GeV, thus satisfying the requirement that the predicted
density fluctuations of the MSM be in agreement with the observed CMB data.


title: The GRB-SN connection: GRB030329 and XRF030723

abstract:
  The attempt to secure conclusive, spectroscopic evidence for the GRB/SN
connection has been a central theme in most GRB observing time proposals since
the discovery of the very unusual GRB980425 associated with the peculiar type
Ib/c SN1998bw. GRB030329 provided this evidence to everybody's satisfaction. In
this contribution we show the results of a spectroscopic campaign of the
supernova associated with GRB030329 carried out at ESOs Very Large Telescope.
We also present preliminary results from a photometric and spectroscopic
campaign targeting the X-ray Flash of July 23.


title: Thermodynamics, Spectral Distribution and the Nature of Dark Energy

abstract:
  Recent astronomical observations suggest that the bulk of energy in the
Universe is repulsive and appears like a dark component with negative pressure
($\omega \equiv p_x/\rho_x < 0$). In this work we investigate thermodynamic and
statistical properties of such a component. It is found that its energy and
temperature grow during the evolution of the Universe since work is done on the
system. Under the hypothesis of a null chemical potential, the case of phantom
energy ($\omega < -1$) seems to be physically meaningless because its entropy
is negative. It is also proved that the wavelengths of the $\omega$-quanta
decrease in an expanding Universe. This unexpected behavior explains how their
energy may be continuously stored in the course of expansion. The spectrum and
the associated Wien-type law favors a fermionic nature with $\omega$ naturally
restricted to the interval $-1 \leqslant \omega < -1/2$. Our analysis also
implies that the ultimate fate of the Universe may be considerably modified. If
a dark energy dominated Universe expands forever, it will become increasingly
hot.


title: Spectral dating of high-redshift stellar populations

abstract:
  (Abridged) Age derivation techniques for unresolved stellar populations at
high redshifts are explored using the NUV spectrum of LBDS~53W091 and
LBDS~53W069. The photometry and morphology of these galaxies suggest they are
early-type systems,a feature that makes them ideal test beds for the analysis
of their ages and metallicities. In the analysis that is based on simple
stellar population models,we find a significant degeneracy between the derived
ages and metallicities both in optical+NIR photometric and NUV spectroscopic
analyses. This degeneracy is not so strong for LBDS~53W069. However even in
this case the stellar age cannot be constrained better than to a range roughly
encompassing one third of the age of the Universe at the observed redshift. We
have explored several independent population synthesis models and consistently
found similar results. Broadband photometry straddling the rest-frame 4000A
break is also subject to a strong age-metallicity degeneracy. The use of
realistic chemical enrichment assumptions significantly helps in disentangling
the degeneracy. Based on this method, we derive the average stellar age for
both galaxies around 3.6-3.8 Gyr with better constraints on the youngest
possible ages. From the observational point of view, the most efficient (and
feasible) way to set limits on unresolved stellar populations comprises a
combination of Balmer absorption lines along with either low SNR rest frame NUV
spectroscopy or accurate optical and NIR photometry.


title: Convergence and scatter of cluster density profiles

abstract:
  We present new results from a series of LCDM simulations of cluster mass
halos resolved with high force and mass resolution. These results are compared
with recently published simulations from groups using various codes including
PKDGRAV, ART, TPM, GRAPE and GADGET. Careful resolution tests show that with 25
million particles within the high resolution region we can resolve to about
0.3% of the virial radius and that convergence in radius is proportional to the
mean interparticle separation. The density profiles of 26 high resolution
clusters obtained with the different codes and from different initial
conditions agree very well. The average logarithmic slope at one percent of the
virial radius is $\gamma = 1.26$ with a scatter of $\pm 0.17$. Over the entire
resolved regions the density profiles are well fitted by a smooth function that
asymptotes to a central cusp $\rho \propto r^{-\gamma}$, where we find
$\gamma=1.16\pm 0.14$ from the mean of the fits to our six highest resolution
clusters.


title:
Mkn 1239: A highly polarized NLS1 with a steep X-ray spectrum and strong
  NeIX emission

abstract:
  We report the results of an XMM-Newton observation of the Narrow-Line Seyfert
1 galaxy Mkn 1239. This optically highly polarized AGN has one of the steepest
X-ray spectra found in AGN with alpha-X = +3.0 based on ROSAT PSPC data. The
XMM-Newton EPIC PN and MOS data confirm this steep X-ray spectrum. The PN data
are best-fit by a powerlaw with a partial covering absorption model suggesting
two light paths between the continuum source and the observer, one indirect
scattered one which is less absorbed and a highly absorbed direct light path.
This result agrees with the wavelength dependent degree of polarization in the
optical/UV band. Residuals in the X-ray spectra of all three XMM-Newton EPIC
detectors around 0.9 keV suggest the presence of an emission line feature, most
likely the Ne IX triplet. The detection of NeIX and the non-detection of
OVII/OVIII suggest a super-solar Ne/O ratio.


title:
TP-AGB stars to date high-redshift galaxies with the Spitzer Space
  Telescope

abstract:
  We present new stellar population models that include the contribution of the
Thermally Pulsing Asymptotic Giant Branch (TP-AGB) phase also in the synthetic
spectral energy distribution (SED). The TP-AGB phase is essential for a correct
modeling of intermediate-age (0.2 < t/Gyr < 1-2) stellar populations, because
it provides ~40% of the bolometric contribution, and up to ~80% of that in the
K-band. These models are obtained by coupling the energetic of the TP-AGB phase
as calibrated with data of Magellanic Clouds star clusters (Maraston 1998),
with empirical spectra of TP-AGB stars (Lancon & Mouchine 2002). Now that the
Spitzer Space Telescope (SST) allows the sight of the rest-frame IR at high
redshifts, these models provide the opportunity to use the TP-AGB phase as an
age indicator also for high-redshift stellar populations. Here we focus on
redshift 3 and provide predictions of the colours of various galaxy models as
will be measured by means of the IRAC imaging instrument on board the SST. We
find a sizable magnitude difference between TP-AGB-dominated high-redshift
stellar populations and those being older or younger. The first releases of
GOODS data should allow a check of these predictions.


title: The mysterious nature of HS2331+3905

abstract:
  We report the discovery of one unique cataclysmic variable drawn from the
Hamburg Quasar Survey, HS2331+3905. Follow-up observations obtained over three
years unveiled a very unusual picture. The large amplitude 3.5 h radial
velocity variations obtained from our optical spectroscopy is not the orbital
period of the system, as one would normally expect. Instead, extensive CCD
photometry strongly suggests that HS2331+3905 is a short orbital period
cataclysmic variable with Porb = 81.09 min, containing a cold white dwarf which
appears to exhibit ZZ Ceti pulsations.


title:
Synthetic stellar populations: single stellar populations, stellar
  interior models and primordial proto-galaxies

abstract:
  We present a new set of stellar interior and synthesis models for predicting
the integrated emission from stellar populations in star clusters and galaxies
of arbitrary age and metallicity. This work differs from existing spectral
synthesis codes in a number of important ways, namely (1) the incorporation of
new stellar evolutionary tracks, with sufficient resolution in mass to sample
rapid stages of stellar evolution; (2) a physically consistent treatment of
evolution in the HR diagram, including the approach to the main sequence and
the effects of mass loss on the giant and horizontal-branch phases. Unlike
several existing models, ours yield consistent ages when used to date a coeval
stellar population from a wide range of spectral features and colour indexes.
We rigorously discuss degeneracies in the age-metallicity plane and show that
inclusion of spectral features blueward of 4500 AA, suffices to break any
remaining degeneracy and that with moderate S/N spectra (10 per 20AA,
resolution element) age and metallicity are not degenerate. We also study
sources of systematic errors in deriving the age of a single stellar population
and conclude that they are not larger than 10-15%. We illustrate the use of
single stellar populations by predicting the colors of primordial
proto-galaxies and show that one can first find them and then deduce the form
of the IMF for the early generation of stars in the universe. Finally, we
provide accurate analytic fitting formulas for ultra fast computation of colors
of single stellar populations. The models can be found at
http://www.physics.upenn.edu/~raulj


title:
Preliminary Parallaxes of 40 L and T Dwarfs from the U.S. Naval
  Observatory Infrared Astrometry Program

abstract:
  We present preliminary trigonometric parallaxes and proper motions for 22 L
dwarfs and 18 T dwarfs measured using the ASTROCAM infrared imager. Relative to
absolute parallax corrections are made by employing 2MASS and/or SDSS
photometry for reference frame stars. We combine USNO infrared and optical
parallaxes with the best available CIT system photometry to determine M_J, M_H,
and M_K values for 37 L dwarfs between spectral types L0 to L8 and 19 T dwarfs
between spectral types T0.5 and T8 and present selected absolute magnitude
versus spectral type and color diagrams, based on these results. Luminosities
and temperatures are estimated for these objects. Of special interest are the
distances of several objects which are at or near the L-T dwarf boundary so
that this important transition can be better understood. The previously
reported early-mid T dwarf luminosity excess is clearly confirmed and found to
be present at J, H, and K. The large number of objects that populate this
luminosity excess region indicates that it cannot be due entirely to selection
effects. The T dwarf sequence is extended to M_J~16.9 by 2MASS J041519-0935
which, at d = 5.74 pc, is found to be the least luminous [log(L/L_sun)=-5.58]
and coldest (T_eff~760 K) brown dwarf known. Combining results from this paper
with earlier USNO CCD results we find that, in contrast to the L dwarfs, there
are no examples of low velocity (V_tan < 20 km/s) T dwarfs. We briefly discuss
future directions for the USNO infrared astrometry program.


title:
Phototmetry of V1062 Tau: low states, short outbursts, and
  period-switching

abstract:
  Time resolved photometry of the long-period intermediate polar V1062 Tau
confirmed the presence of the previously reported orbital and spin periods, and
revealed the presence of a third one, corresponding to the beat of the two.
While the orbital periodicity was present throughout our data, only one of the
shorter periods was detectable at any given time. On a time-scale of ~90 days,
the short-period modulation in the light curve of the star changed three times
between the spin period and the beat. On longer time-scales, we report two
outbursts of V1062 Tau (the first to be recorded for this object) - both of
which were probably short, low-amplitude ones (dm ~1.2 mag). Our data also
suggest a brief low state phase in 2002 Jan. Thus, this system joins two
exclusive groups of intermediate polars: those undergoing short outbursts, and
those having low states. We propose that the alternations between the short
periods that modulate the light curve were caused by changes in the accretion
mode, from disc-fed accretion, to disc-overflow accretion. We further suggest
that these changes may have been triggered by changes in mass-transfer rate,
which were manifested by the low-state/outburst activity of the system.


title: VLA HI and OVRO CO Interferometry of a Tidal Dwarf Galaxy

abstract:
  We present high resolution interferometric observations of the cool atomic
and cold molecular ISM of the TDG candidate Arp 245N, an object resembling a
dwarf galaxy in the northern tidal tail of the interacting system NGC 2992/3.
We observed the HI line with the NRAO VLA and the CO(1-->0) transition with the
OVRO millimeter interferometer at 5''-6'' angular resolution (750 pc linear
resolution). These datacubes offer the required spatial and velocity resolution
to determine whether the mass concentration near the tip of the tail is a
genuine feature, and hence a good TDG candidate, or an artefact caused by a
fortuitous alignment of our line of sight with the direction of the tail. A
preliminary analysis seems to confirm that Arp 245N is a self-gravitating
entity.


title: The Development and Scientific Impact of the Chandra X-Ray Observatory

abstract:
  I review the operational capabilities of the Chandra X-ray Observatory,
including some of the spectacular results obtained by the general observer
community. A natural theme of this talk is that Chandra is revealing outflows
of great quantities of energy that were not previously observable. I highlight
the Chandra studies of powerful X-ray jets. This subject is only possible due
to the sub-arcsecond resolution of the X-ray telescope.


title:
Down-Sizing in Galaxy Formation at z~1 in the Subaru/XMM-Newton Deep
  Survey (SXDS)

abstract:
  We use the deep wide-field optical imaging data of the Subaru/XMM-Newton Deep
Survey (SXDS) to discuss the luminosity (mass) dependent galaxy colours down to
z'=25.0 (5 x 10^9 h_{70}^{-2} Msun) for z~1 galaxies in colour-selected high
density regions. We find an apparent absence of galaxies on the red
colour-magnitude sequence below z'~24.2, corresponding to ~M*+2 (~10^{10} Msun)
with respect to passively evolving galaxies at z~1. Galaxies brighter than
M*-0.5 (8 x 10^{10} Msun), however, are predominantly red passively evolving
systems, with few blue star forming galaxies at these magnitudes.
  This apparent age gradient, where massive galaxies are dominated by old
stellar populations while less massive galaxies have more extended star
formation histories, supports the `down-sizing' idea where the mass of galaxies
hosting star formation decreases as the Universe ages. Combined with the lack
of evolution in the shape of the stellar mass function for massive galaxies
since at least z~1, it appears that galaxy formation processes (both star
formation and mass assembly) should have occurred in an accelerated way in
massive systems in high density regions, while these processes should have been
slower in smaller systems. This result provides an interesting challenge for
modern CDM-based galaxy formation theories which predict later formation epochs
of massive systems, commonly referred to as ``bottom-up''.


title:
Extreme Kuiper Belt Object 2001 QG298 and the Fraction of Contact
  Binaries

abstract:
  Extensive time-resolved observations of Kuiper Belt object 2001 QG298 show a
lightcurve with a peak-to-peak variation of 1.14 +-0.04 magnitudes and
single-peaked period of 6.8872 +- 0.0002 hr. The mean absolute magnitude is
6.85 magnitudes which corresponds to a mean effective radius of 122 (77) km if
an albedo of 0.04 (0.10) is assumed. This is the first known Kuiper Belt object
and only the third minor planet with a radius > 25 km to display a lightcurve
with a range in excess of 1 magnitude. We find the colors to be typical for a
Kuiper Belt object (B-V = 1.00 +- 0.04, V-R = 0.60 +- 0.02) with no variation
in color between minimum and maximum light. The large light variation,
relatively long double-peaked period and absence of rotational color change
argue against explanations due to albedo markings or elongation due to high
angular momentum. Instead, we suggest that 2001 QG298 may be a very close or
contact binary similar in structure to what has been independently proposed for
the Trojan asteroid 624 Hektor. If so, its rotational period would be twice the
lightcurve period or 13.7744 +- 0.0004 hr. By correcting for the effects of
projection, we estimate that the fraction of similar objects in the Kuiper Belt
is at least 10% to 20% with the true fraction probably much higher. A high
abundance of close and contact binaries is expected in some scenarios for the
evolution of binary Kuiper Belt objects.


title: Fundamental Aspects of the Expansion of the Universe and Cosmic Horizons

abstract:
  In the context of the new standard LambdaCDM cosmology we resolve conflicts
in the literature regarding fundamental aspects of the expansion of the
universe and cosmic horizons and we link these concepts to observational tests.
We derive the dynamics of a non-comoving galaxy and use this to demonstrate the
counter-intuitive result that objects at constant proper distance can have a
non-zero redshift. Receding galaxies can be blueshifted and approaching
galaxies can be redshifted, even in an empty universe for which one might
expect special relativity to apply.
  We then test the generalized second law of thermodynamics (GSL) and its
extension to incorporate cosmological event horizons. In spite of the fact that
cosmological horizons do not generally have well-defined thermal properties, we
find that the GSL is satisfied for a wide range of models. We explore in
particular the relative entropic 'worth' of black hole versus cosmological
horizon area. An intriguing set of models show an apparent entropy decrease but
we anticipate this apparent violation of the GSL will disappear when solutions
are available for black holes embedded in arbitrary backgrounds.
  Recent evidence suggests a small increase in the fine structure constant
(alpha =e^2/hbar c) over cosmological time scales. This raises the question of
which fundamental quantities are truly constant and which might vary. We show
that black hole thermodynamics may provide a means to discriminate between
alternative theories invoking varying constants, because some variations in the
fundamental 'constants' could lead to a violation of the generalized second law
of thermodynamics.


title: Accurate Modelling of Relativistic Iron Lines from Accretion Discs

abstract:
  Observations of fluorescent iron lines from accreting black holes provide one
of the best tests of strong field gravity available to date, and the only
current observational tool to probe black hole spacetime. However, the two most
widely used models for spectral fitting (diskline, laor) are over a decade old
and have significant limitations. We present a new code for calculating these
effects which will be incorporated within the XSPEC package


title: Planetary Nebulae Near the Galactic Center: Identifications

abstract:
  We surveyed the central 4 x 4 degrees of the Galactic center for planetary
nebulae in the light of [S III] 9532 A and found 94 PNe that were not
previously known, plus 3 that were previously identified as possible
candidates. For 63 of these 97 objects, we obtained spectra that are consistent
with highly reddened PN while the other 34 could not be recovered
spectroscopically and remain unverified. Of the 94 candidates, 54 and 57 were
detected via radio at 3 and 6 cm, respectively. An additional 20 PNe candidates
were found during follow-up Halpha imaging but have not yet been verified
spectroscopically. Based on the properties of IRAS sources in this region of
the Galaxy, and on the total luminosity of the Galactic bulge, the expected
number of PNe is ~250, only 50 % more than the 160 PNe candidates now known.
Thus, surveys for PNe in the bulge are approximately two-thirds complete with
the remainder likely hidden behind dust.


title: Suppression of small scale dynamo action by an imposed magnetic field

abstract:
  Non-helical hydromagnetic turbulence with an externally imposed magnetic
field is investigated using direct numerical simulations. It is shown that the
imposed magnetic field lowers the spectral magnetic energy in the inertial
range. This is explained by a suppression of the small scale dynamo. At large
scales, however, the spectral magnetic energy increases with increasing imposed
field strength for moderately strong fields, and decreases only slightly for
even stronger fields. The presence of Alfven waves is explicitly confirmed by
monitoring the evolution of magnetic field and velocity at one point. The
frequency omega agrees with vA k1, where vA is the Alfven speed and k1 is the
smallest wavenumber in the box.


title: Pulsar motions in our Galaxy

abstract:
  Pulsar motions in our Galaxy from their birth until 2 Gyr are studied
statistically via Monte-Carlo simulation of $2\times 10^5$ pulsars with the
best available representation of the Galactic potential. We find that the
distribution of height above the Galactic plane for pulsars with characteristic
ages less than about 8 Myr could be well fitted by a Gaussian function. For
older pulsars, an extra exponential function is necessary to fit the
distribution. The scale-height of the Gaussian component increases linearly
with time until about 40 Myr. The height distribution becomes stabilized after
about 200 Myr. These results are not sensitive to initial height or radial
distributions. Taking the relationship between the initial velocity and height
distribution, we found from the latest pulsar catalog that the height
distribution of pulsars younger than 1 Myr directly implies the mean initial
velocity of $280\pm96$ km s$^{-1}$. Comparison of simulated sample of pulsars
with the current available millisecond pulsars shows that their 1D initial
velocity dispersion should be most probably $60\pm10$ km s$^{-1}$.


title: Normal Galaxies - INES Guide No. 2

abstract:
  This guide presents, in a uniform manner, all the information collected by
the IUE satellite on normal galaxies. It contains information on 274 galaxies
and it supersedes the previous IUE guide to normal galaxies (Longo & Capaccioli
1992). The data shown here are restricted to galaxies defined as ``normal'' by
the observer, and entered as such in the IUE data file header. The information
is also restricted to low-dispersion spectra obtained through the large
apertures of IUE. For the first time, we provide spectral information from
well-defined and identifiable locations in the target galaxies. These are
mostly located close to the photocenter of each object, although there are few
exceptions. Each representative spectrum of a galaxy consists of a short-wave
(SW) and a long-wave (LW) IUE low-dispersion spectrum (where available)
combined into a single spectrum covering the wavelength range 1150 A to 3350 A.
We selected the two spectra to be combined so as to be, preferably, the deepest
exposures available in the INES archive. Each representative spectrum is
accompanied by two images of the galaxy, on which the locations of the SW
entrance aperture and the LW entrance aperture are marked. The guide is
available at (http://wise-iue.tau.ac.il/~lili/Fnet/Fnet.html)


title: Principal component analysis of IUE galaxy spectra

abstract:
  We analyse the UV spectral energy distribution of a sample of normal galaxies
listed in the IUE-INES Guide No. 2-Normal Galaxies (Formiggini & Brosch, 2000)
using a Principal Component Analysis. The sample consists of the IUE-SW spectra
of the central regions of 118 galaxies, where the IUE aperture included more
than 1 per cent of the galaxy size. The principal components are associated
with the main components observed in the UV spectra of galaxies. The first
component, accounting for the largest source of diversity, can be associated
with the UV continuum emission. The second component represents the UV
contribution of an underlying evolved stellar population. The third component
is sensitive to the amount of activity in the central regions of galaxies and
measures the strength of star formation events. In all the samples analysed
here the principal component representative of star-forming activity accounts
for a significant percentage of the variance. The fractional contribution to
the SED by the evolved stars and by the young population are similar.
Projecting the SEDs onto their eigenspectra, we find that none of the
coefficients of the principal components can outline an internal correlation or
can correlate with the optical morphological types. In a sub-sample of 43
galaxies, consisting of almost only compact and BCD galaxies, the third
principal component defines a sequence related to the degree of starburst
activity of the galaxy.


title: Unidentified Gamma-Ray Sources and Microquasars

abstract:
  Some phenomenological properties of the unidentified EGRET detections suggest
that there are two distinct groups of galactic gamma-ray sources that might be
associated with compact objects endowed with relativistic jets. We discuss
different models for gamma-ray production in both microquasars with low- and
high-mass stellar companions. We conclude that the parent population of
low-latitude and halo variable sources might be formed by yet undetected
microquasars and microblazars.


title:
The first binary star evolution model producing a Chandrasekhar mass
  white dwarf

abstract:
  Today, Type Ia supernovae are essential tools for cosmology, and recognized
as major contributors to the chemical evolution of galaxies. The construction
of detailed supernova progenitor models, however, was so far prevented by
various physical and numerical difficulties in simulating binary systems with
an accreting white dwarf component, e.g., unstable helium shell burning which
may cause significant expansion and mass loss. Here, we present the first
binary evolution calculation which models both stellar components and the
binary interaction simultaneously, and where the white dwarf mass grows up to
the Chandrasekhar limit by mass accretion. Our model starts with a 1.6 Msun
helium star and a 1.0 Msun CO white dwarf in a 0.124 day orbit. Thermally
unstable mass transfer starts when the CO core of the helium star reaches 0.53
Msun, with mass transfer rates of 1...8 times 10^{-6} Msun/yr. The white dwarf
burns the accreted helium steadily until the white dwarf mass has reached ~ 1.3
Msun and weak thermal pulses follow until carbon ignites in the center when the
white dwarf reaches 1.37 Msun. Although the supernova production rate through
this channel is not well known, and this channel can not be the only one as its
progenitor life time is rather short (~ 10^7 - 10^8 yr), our results indicate
that helium star plus white dwarf systems form a reliable route for producing
Type Ia supernovae.


title: Presupernova evolution of accreting white dwarfs with rotation

abstract:
  We discuss the effects of rotation on the evolution of accreting
carbon-oxygen white dwarfs, with the emphasis on possible consequences in Type
Ia supernova (SN Ia) progenitors. Starting with a slowly rotating white dwarf,
we simulate the accretion of matter and angular momentum from a quasi-Keplerian
accretion disk. The role of the various rotationally induced hydrodynamic
instabilities for the transport of angular momentum inside the white dwarf is
investigated. We find that the dynamical shear instability is the most
important one in the highly degenerate core. Our results imply that accreting
white dwarfs rotate differentially throughout,with a shear rate close to the
threshold value for the onset of the dynamical shear instability. As the latter
depends on the temperature of the white dwarf, the thermal evolution of the
white dwarf core is found to be relevant for the angular momentum
redistribution. As found previously, significant rotation is shown to lead to
carbon ignition masses well above 1.4 Msun. Our models suggest a wide range of
white dwarf explosion masses, which could be responsible for some aspects of
the diversity observed in SNe Ia. We analyze the potential role of the bar-mode
and the r-mode instability in rapidly rotating white dwarfs, which may impose
angular momentum loss by gravitational wave radiation. We discuss the
consequences of the resulting spin-down for the fate of the white dwarf, and
the possibility to detect the emitted gravitational waves at frequencies of 0.1
>... 1.0 Hz in nearby galaxies with LISA. Possible implications of fast and
differentially rotating white dwarf cores for the flame propagation in
exploding white dwarfs are also briefly discussed.


title:
Helium accreting CO white dwarfs with rotation: helium novae instead of
  double detonation

abstract:
  We present evolutionary models of helium accreting carbon-oxygen white dwarfs
in which we include the effects of the spin-up of the accreting star induced by
angular momentum accretion, rotationally induced chemical mixing and rotational
energy dissipation. Initial masses of 0.6 Msun and 0.8 Msun and constant
accretion rates of a few times 10^{-8} Msun/yr of helium rich matter have been
considered, which is typical for the sub-Chandrasekhar mass progenitor scenario
for Type Ia supernovae. It is found that the helium envelope in an accreting
white dwarf is heated efficiently by friction in the differentially rotating
spun-up layers. As a result, helium ignites much earlier and under much less
degenerate conditions compared to the corresponding non-rotating case.
Consequently, a helium detonation may be avoided, which questions the
sub-Chandrasekhar mass progenitor scenario for Type Ia supernovae. We discuss
implications of our results for the evolution of helium star plus white dwarf
binary systems as possible progenitors of recurrent helium novae.


title: Long-term IR Photometry of Seyferts

abstract:
  Long-term (up to 10000d) monitoring has been undertaken for 41 Seyferts in
the near-IR (JHKL). All but 2 showed variability, with K ampl in the range <0.1
to > 1.1 mags. The timescale for detectable change is from about one week to a
few years. A simple cross-correlation study shows evidence for delays of up to
several hundred days between the variations seen at the shortest wavelengths
and the longest in many galaxies. In particular, the data for F9 now extend to
twice the interval covered earlier and the delay between its UV and IR outputs
persists. An analysis of the fluxes shows that, for any given galaxy, the
colours of the variable component are usually independent of the level of
activity. The state of activity can be parameterized. Taken over the whole
sample, the colours of the variable components fall within moderately narrowly
defined ranges. In particular, the H-K colour is appropriate to a black body of
temperature 1600K. The H-K excess for a heavily reddened nucleus can be
determined and used to find E_{B-V}, which can be compared to the values found
from the visible region broad line fluxes. Using flux-flux diagrams, the flux
within the aperture from the underlying galaxy can often be determined without
the need for model surface brightness profiles. In many galaxies it is apparent
that here must be an additional constant contribution from warm dust.


title: Results concerning the centre of our galaxy

abstract:
  For many years it was felt that, when a star collapsed, a white dwarf
resulted if the mass of the original star was below the Chandrasekhar limit, a
neutron star if the mass was somewhat larger but still less than four or five
solar masses, but after that black holes were felt to provide the only possible
final state. The extension of this hierarchy to include the possibility of
quark, and even sub-quark, stars has been proposed and here is used to offer an
alternative explanation for the recently published photograph, credited to
Eckart and Genzel, purporting to show stars near the centre of our Galaxy
moving at very high speeds. The same basic results are used also to consider
the even more recent results of Schodel and collaborators concerning the
detailed observations of a stellar orbit very close to the centre of our
galaxy.


title:
Spectroscopic Studies of Extremely Metal-Poor Stars with Subaru/HDS:I.
  Observational Data

abstract:
  We have obtained high-resolution (R $\simeq$ 50,000 or 90,000), high-quality
(S/N $\ga$ 100) spectra of 22 very metal-poor stars ([Fe/H] $\la$ -2.5) with
the High Dispersion Spectrograph fabricated for the 8.2m Subaru Telescope. The
spectra cover the wavelength range from 3500 to 5100 {\AA}; equivalent widths
are measured for isolated lines of numerous elemental species, including the
$\alpha$ elements, the iron-peak elements, and the light and heavy
neutron-capture elements. Errors in the measurements and comparisons with
previous studies are discussed. These data will be used to perform detailed
abundance analyses in the following papers of this series. Radial velocities
are also reported, and are compared with previous studies. At least one
moderately r-process-enhanced metal-poor star, HD 186478, exhibits evidence of
a small-amplitude radial velocity variation, confirming the binary status noted
previously. During the course of this initial program, we have discovered a new
moderately r-process-enhanced, very metal-poor star, CS 30306-132 ([Fe/H] $=
-2.4$; [Eu/Fe] $= +0.85$), which is discussed in detail in the companion paper.


title: Long-term evolution of FU Ori-type stars at infrared wavelengths

abstract:
  FU Orionis-type stars form a small class of variable Young Stellar Objects,
defined by an optical outburst of 5-6 mag followed by gradual fading on a
timescale of decades. Since the phenomenon is connected to the circumstellar
medium the infrared emission spectrum is also expected to change after the
outburst. The fading phase after the outburst is well documented in the
optical/near-infrared, but not at far-infrared wavelengths.
  We investigated the brightness evolution of 7 FU Orionis systems in the 1-200
\mu m wavelength range. We compiled spectral energy distributions (SEDS) using
data from the Infared Space Observatory, 2MASS and MSX (these observations were
performed around 1995-1998). These SEDs were compared with earlier ones based
on IRAS photometry and ground-based observations carried out around 1983.
  During this period of 15 years some objects remained unchanged, while others
became fainter, but only in the near- and mid-infrared part of the spectrum.
Since the wavelength dependence of the fading provides crucial information on
the physics of the phenomenon, we studied in detail the case of V1057 Cyg.


title: XMM-Newton observations of the INTEGRAL X-ray transient J17544-2619

abstract:
  On 2003 September 17 INTEGRAL discovered a bright transient source 3 degrees
from the Galactic Center, IGR J17544-2619. The field containing the transient
was observed by XMM-Newton on 2003 March 17 and September 11 and 17. A bright
source, at a position consistent with the INTEGRAL location, was detected by
the European Photon Imaging Camera (EPIC) during both September observations
with mean 0.5-10 keV unabsorbed luminosities of 1.1x10^35 and 5.7x10^35 erg s-1
for an (assumed) distance of 8 kpc. The source was not detected in 2003 March,
with a 0.5-10 keV luminosity of < 3.8x10^32 erg s-1. The September 11 and 17
EPIC spectra can be represented by a power-law model with photon indices of
2.25+/-0.15 and 1.42+/-0.17, respectively. Thus, the 0.5-10 keV spectrum
hardens with increasing intensity. The low-energy absorption during both
September observations is comparable to the interstellar value. The X-ray
lightcurves for both September observations show energy dependent flaring which
may be modeled by changes in either low-energy absorption or power-law index.


title:
Discovery of X-ray absorption features from the dipping low-mass X-ray
  binary XB 1916-053 with XMM-Newton

abstract:
  We report the discovery of narrow Fe XXV and Fe XXVI K alpha X-ray absorption
lines at 6.65 and 6.95 keV in the persistent emission of the dipping low-mass
X-ray binary (LMXB) XB 1916-053 during an XMM-Newton observation performed in
September 2002. In addition, there is marginal evidence for absorption features
at 1.48 keV, 2.67 kev, 7.82 keV and 8.29 keV consistent with Mg XII, S XVI, Ni
XXVII K alpha and Fe XXVI K beta transitions, respectively. Such absorption
lines from highly ionized ions are now observed in a number of high inclination
(ie. close to edge-on) LMXBs, such as XB 1916-053, where the inclination is
estimated to be between 60-80 degrees. This, together with the lack of any
orbital phase dependence of the features (except during dips), suggests that
the highly ionized plasma responsible for the absorption lines is located in a
cylindrical geometry around the compact object. Using the ratio of Fe XXV and
Fe XXVI column densities, we estimate the photo-ionization parameter of the
absorbing material to be 10^{3.92} erg cm s^{-1}. Only the Fe XXV line is
observed during dipping intervals and the upper-limits to the Fe XXVI column
density are consistent with a decrease in the amount of ionization during
dipping intervals. This implies the presence of cooler material in the line of
sight during dipping. We also report the discovery of a 0.98 keV absorption
edge in the persistent emission spectrum. The edge energy decreases to 0.87 keV
during deep dipping intervals. The detected feature may result from edges of
moderately ionized Ne and/or Fe with the average ionization level decreasing
from persistent emission to deep dipping. This is again consistent with the
presence of cooler material in the line of sight during dipping.


title: Stellar Abundances in Local Group Galaxies with the VLT

abstract:
  Here we describe some of our latest results from measuring detailed
abundances in Local Group dwarf galaxies with VLT. Combining spectroscopic
abundances with Colour-Magnitude diagrams allows the effective measurement of
detailed chemical evolution with time in these galaxies. Although there are not
yet significant numbers of individual stars observed in local group dwarf
galaxies the uniformity of the abundance patterns of the majority of stars in
galaxies with very different star formation histories must hint at a general
properties of all star formation in these small systems.


title: Cosmological Parameter Estimation: Method

abstract:
  CMB anisotropy data could put powerful constraints on theories of the
evolution of our Universe. Using the observations of the large number of CMB
experiments, many studies have put constraints on cosmological parameters
assuming different frameworks. Assuming for example inflationary paradigm, one
can compute the confidence intervals on the different components of the energy
densities, or the age of the Universe, inferred by the current set of CMB
observations. The aim of this note is to present some of the available methods
to derive the cosmological parameters with their confidence intervals from the
CMB data, as well as some practical issues to investigate large number of
parameters.


title: Cosmological implications from the observed properties of CMB

abstract:
  Observations of the cosmic microwave background represent a remarkable source
of information for modern cosmology. Besides providing impressive support for
the Big Bang model itself, they quantify the overall framework, or background,
for the formation of large scale structure. Most exciting, however, is the
potential access these observations give to the first moments of cosmic history
and to the physics reigning at such exceptionally high energies, which will
remain beyond the reach of the laboratory in any foreseeable future. Upcoming
experiments, such as the Planck mission, thus offer a window onto the Physics
of the Third Millennium.


title:
Spectroscopic Studies of Extremly Metal-Poor Stars with
  Subaru/HDS:II.The r-process Elements, Including Thorium

abstract:
  We present the abundance analyses for the neutron-capture elements, and
discuss the observed abundance distributions in very metal-poor stars with
excesses of r-process elements. As has been found by previous abundance
studies, the star-to-star scatter in the abundances of neutron-capture elements
are very large. The abundance patterns of the heavy neutron-capture elements
(56 $\leq$ Z $\leq$ 70) in seven objects with moderate to large excesses of the
neutron-capture elements are similar to that of the solar system r-process
component. These results strongly suggest that the heavy neutron-capture
elements in these objects are primarily synthesized by the r-process. On the
other hand, the abundance ratios of the light neutron-capture elements (38
$\leq$ Z $\leq$ 46) exhibit a rather large dispersion. Our inspection of the
correlation between Sr and Ba abundances in very metal-poor stars reveals that
the dispersion of the Sr abundances clearly decreases with increasing Ba
abundance. This results support previous suggestions that the light
neutron-capture elements are likely to have been produced in different
astrophysical sites from those associated with the production of the heavier
ones. The Th/Eu abundance ratios (log(Th/Eu)) measured for the seven
r-process-enhanced stars range from -0.10 to -0.59. Since these very metal-poor
stars are believed to be formed in the early Galaxy, this result means that a
small dispersion appears in the abundance ratios between Th and rare-earth
elements, such as Eu, in very metal-poor stars. In order to apply the Th/Eu
ratios to estimates of stellar ages, further understanding for the Th
production by the r-process nucleosynthesis is required.


title: Constraining Warm Inflation with the Cosmic Microwave Background

abstract:
  We discuss the spectrum of scalar density perturbations from warm inflation
when the friction coefficient $\Gamma$ in the inflaton equation is dependent on
the inflaton field. The spectral index of scalar fluctuations depends on a new
slow-roll parameter constructed from $\Gamma$. A numerical integration of the
perturbation equations is performed for a model of warm inflation and gives a
good fit to the WMAP data for reasonable values of the model's parameters.


title: Properties of Extensive Air Showers

abstract:
  Some general properties of extensive air showers are discussed. The main
focus is put on the longitudinal development, in particular the energy flow,
and on the lateral distribution of different air shower components. The
intention of the paper is to provide a basic introduction to the subject rather
than a comprehensive review.


title: Inertial range scaling in numerical turbulence with hyperviscosity

abstract:
  Numerical turbulence with hyperviscosity is studied and compared with direct
simulations using ordinary viscosity and data from wind tunnel experiments. It
is shown that the inertial range scaling is similar in all three cases.
Furthermore, the bottleneck effect is approximately equally broad (about one
order of magnitude) in these cases and only its height is increased in the
hyperviscous case--presumably as a consequence of the steeper decent of the
spectrum in the hyperviscous subrange. The mean normalized dissipation rate is
found to be in agreement with both wind tunnel experiments and direct
simulations. The structure function exponents agree with the She-Leveque model.
Decaying turbulence with hyperviscosity still gives the usual t^{-1.25} decay
law for the kinetic energy, and also the bottleneck effect is still present and
about equally strong.


title:
Effects of asphericity and substructure on the determination of cluster
  mass with weak gravitational lensing

abstract:
  Weak gravitational lensing can be used to directly measure the mass along a
line-of-sight without any dependence on the dynamical state of the mass, and
thus can be used to measure the masses of clusters even if they are not
relaxed. One common technique used to measure cluster masses is fitting
azimuthally-averaged gravitational shear profiles with a spherical mass model.
In this paper we quantify how asphericity and projected substructure in
clusters can affect the virial mass and concentration measured with this
technique by simulating weak lensing observations on 30 independent
lines-of-sights through each of four high-resolution N-body cluster
simulations. We find that the variations in the measured virial mass and
concentration are of a size similar to the error expected in ideal weak lensing
observations and are correlated, but that the virial mass and concentration of
the mean shear profile agree well with that measured in three dimensional
models of the clusters. The dominant effect causing the variations is the
proximity of the line-of-sight to the major axis of the 3-D cluster mass
distribution, with projected substructure only causing minor perturbations in
the measured concentration. Finally we find that the best-fit "universal" CDM
models used to fit the shear profiles over-predict the surface density of the
clusters due to the cluster mass density falling off faster than the r^{-3}
model assumption.


title: An X-ray View of Radio Sources

abstract:
  We review recent examples where the synergy between radio and X-ray
observations has led to substantial progress in understanding astronomical
systems. The sub-arcsecond imaging capabilities of the Chandra X-ray
observatory provides a 100-fold improvement for comparing X-ray and radio
structures. We specifically discuss examples which provide insight into the
outflow of material and energy from pulsars and supernovae, the centers of
clusters of galaxies, and the nuclei of quasars.


title: On the anomalous acceleration in the solar system

abstract:
  We study the impact of the cosmological environment on the solar
gravitational system by the imbedding formalism of Gautreau. It appears that
the cosmic mean-mass density and the cosmological constant give negligibly
small contribution to gravity potentials. On the contrary, the cosmic
acceleration beyond the Robertson-Walker geometry can considerably influence
the curvature of spacetime in the solar system. The resulting anomalous
constant acceleration towards the Sun is an order of magnitude smaller than
that measured by Pioneer 10 and 11. However, it is larger than second order
terms of potentials, thus well within the sensitivity of new gravity probes
such as the LATOR mission.


title: Chemical composition of UV-bright star ZNG 4 in the globular cluster M13

abstract:
  We present a detailed model-atmosphere analysis of ZNG 4, a UV-bright star in
the globular cluster M13. From the analysis of a high resolution ($ R \approx
45,000 $) spectrum of the object, we derive the atmospheric parameters to be
$\rm T_{eff} = 8500\pm 250$ K, log g $=$ 2.5 $\pm$ 0.5 and $\rm [Fe/H]= -1.5$.
Except for magnesium, chromium and strontium, all other even Z elements are
enhanced with titanium and calcium being overabundant by a factor of 0.8 dex.
Sodium is enhanced by a factor of 0.2 dex. The luminosity of ZNG 4 and its
position in the color-magnitude diagram of the cluster indicate that it is a
Supra Horizontal Branch (SHB) (post-HB) star. The underabundance of He and
overabundances of Ca, Ti, Sc and Ba in the photosphere of ZNG 4 indicate that
diffusion and radiative levitation of elements may be in operation in M 13
post-HB stars even at $\rm T_{eff}$ of 8500K. Detailed and more accurate
abundance analysis of post-HB stars in several globular clusters is needed to
further understand their abundance anomalies.


title:
Planets in Stellar Clusters Extensive Search. II. Discovery of 57
  Variables in the Cluster NGC 2158 with Millimagnitude Image Subtraction
  Photometry

abstract:
  We have undertaken a long-term project, Planets in Stellar Clusters Extensive
Search (PISCES), to search for transiting planets in open clusters. NGC 2158 is
one of the targets we have chosen -- an intermediate age, populous, rather
metal poor cluster. In this paper we present the results of a search for
variable stars in the data from the first season of monitoring at the FLWO 1.2
m telescope. This is the first variability search ever conducted in this
cluster. We present a catalog of 57 variable stars, most with low amplitude
variability. Among the variables is a cataclysmic variable (CV) which underwent
a 2.5 mag outburst. If it is a member of NGC 2158, this would be the fourth CV
known in an open cluster. We have also found five delta Scuti stars, three of
which we have two or more detectable modes of pulsation. Of the 57 variables
discovered, 28 have R-band amplitudes of 5% or below. Six of those vary at or
below the 2% level, including one with 0.08% variability.


title: A pair of gigantic bipolar dust jets close to the solar system

abstract:
  We report the discovery of two adjacent jet candidates with a length of about
9 degrees each -- 10 times longer than the largest known jets -- detected by us
on 60 and 100 micron IRAS maps, but not observed at any other wavelength. They
are extremely collimated (length-to-width ratios 20--50), curved, knotty, and
end in prominent bubbles. Their dust temperatures are 25 K and 30 K,
respectively. Both harbour faint stars, one having a high proper motion (0.23
arcsec/yr) and being very red, suggesting a distance of about 60 pc. At this
distance, the total mass of both jet candidates is about about 1 solar mass. We
suspect that these gigantic (9 pc length respectively) jets are of fossil type
and have a common origin, due to the decay of a system of evolved stars. They
are the first examples of jets radiating in the far IR and might, because of
their closeness, be of interest for further studies of the acceleration and
collimation processes of astrophysical jets.