title:
Probing dark energy with baryonic oscillations and future radio surveys
  of neutral Hydrogen

abstract:
  Current surveys may be on the verge of measuring the baryonic oscillations in
the galaxy power spectrum which are clearly seen imprinted on the Cosmic
Microwave Background. It has recently been proposed that these oscillations
allow a `standard ruler' method of probing the equation of state of dark
energy. In this paper we present a new calculation of the number of galaxies
future adio telescopes will detect in surveys of the sky in neutral Hydrogen
(HI). We estimate the likely statistical errors if the standard ruler method
were to be applied to such surveys. We emphasise uncertainties in our
calculations, and pinpoint the most important features of future HI surveys if
they are to provide new constraints on dark energy via baryonic oscillations.
Designs of future radio telescopes are required to have a large bandwidth
(characterised by \beta$, the ratio of the instantaneous bandwidth to the
bandwidth required by survey) and to have the widest instantaneous (1.4 GHz)
field of view ($FOV$) possible. Given the expected sensitivity of a future
Square Kilometre Array (SKA), given that half of its collecting area will be
concentrated in a core of diameter $\sim 5 ~ \rm km$, and given a reasonable
survey duration ($T_0$ $\sim$ 1 yr), we show that there will be negligible shot
noise on a power spectrum derived from HI galaxies out to redshift $z \simeq
1.5$. To access the largest cosmic volume possible by surveying all the sky
available, we argue that $\beta$, $T_0$ and $FOV$ must obey the relation $\beta
FOV T_0 \gtsimeq 10 \rm deg^2$ yr. An $\sim$1-yr SKA survey would then contain
$\gtsimeq 10^{9} (f_{\rm sky}/0.5)$ HI galaxies and provide constraints on the
dark-energy parameter $w$ of order $\Delta w \simeq 0.01 (f_{\rm
sky}/0.5)^{-0.5}$.


title:
Dust attenuation in the nearby Universe: comparison between galaxies
  selected in the ultraviolet or in the infrared

abstract:
  We compare the dust attenuation properties of two samples of galaxies purely
selected in the near-ultraviolet (NUV) band (1750-2750 A, lambda_m = 2310 A)
and in the far-infrared (FIR) at 60micron. These samples are built using the
GALEX and IRAS sky surveys over ~600 square degrees. The NUV selected sample
contains 95 galaxies detected down to NUV=16mag (AB system). 83 galaxies in
this sample are spirals or irregulars and only two of them are not detected at
60micron. The FIR selected sample is built from the IRAS PSCz catalog complete
down to 0.6Jy. Among the 163 sources, we select 118 star forming galaxies well
measured by IRAS, all but 1 are detected in NUV and 14 galaxies are not
detected in the far-ultraviolet (FUV) band (1350-1750 A, lambda_m = 1530 A).
The dust to ultraviolet (NUV and FUV) flux ratio is calibrated to estimate the
dust attenuation at both wavelengths. The median value of the attenuation in
NUV is found to be ~1 mag for the NUV selected sample versus ~2 mag for the FIR
selected one. Within both samples, the dust attenuation is found to correlate
with the luminosity of the galaxies. Almost all the NUV selected galaxies and
2/3 of the FIR selected sample exhibit a lower dust attenuation than that
expected from the tight relation found previously for starburst galaxies
between the dust attenuation and the slope of the ultraviolet continuum. The
situation is inverse for one third of the FIR selected galaxies: their
extinction is higher than that deduced from their FUV-NUV color and the
relation valid for starbursts.


title: Massive galaxies at redshift 2 in cosmological hydrodynamic simulations

abstract:
  We study the properties of galaxies at z=2 in a Lambda cold dark matter
universe, using two different types of hydrodynamic simulation methods --
Eulerian TVD and smoothed particle hydrodynamics (SPH) -- and a
spectrophotometric analysis in the U_n, G, R filter set. The simulated galaxies
at z=2 satisfy the color-selection criteria proposed by Adelberger et al.
(2004) and Steidel et al. (2004) when we assume Calzetti extinction with
E(B-V)=0.15. We find that the number density of simulated galaxies brighter
than R<25.5 at z=2 is about 1e-2 h^3 Mpc^-3 for E(B-V)=0.15, which is roughly
twice that of the number density found by Erb et al. (2004) for the UV bright
sample. This suggests that roughly half of the massive galaxies with M*>10^{10}
Msun/h at z=2 are UV bright population, and the other half is bright in the
infra-red wavelengths. The most massive galaxies at z=2 have stellar masses >=
10^{11-12} Msun. They typically have been continuously forming stars with a
rate exceeding 30 Msun/yr over a few Gyrs from z=10 to z=2, together with
significant contribution by starbursts reaching up to 1000 Msun/yr which lie on
top of the continuous component. TVD simulations indicate a more sporadic star
formation history than the SPH simulations. Our results do not imply that
hierarchical galaxy formation fails to account for the observed massive
galaxies at z>=1. The global star formation rate density in our simulations
peaks at z>=5, a much higher redshift than predicted by the semianalytic
models. This star formation history suggests early build-up of the stellar mass
density, and predicts that 70 (50, 30)% of the total stellar mass at z=0 had
already been formed by z=1 (2, 3). Upcoming observations by Spitzer and Swift
might help to better constrain the star formation history at high redshift.


title:
Modeling the Stellar Spectral Energy Distributions of Star-Forming
  Galaxies

abstract:
  I will review recent progress in the modeling of the stellar spectral energy
distributions of star-forming galaxies. I will cover the full relevant
wavelength range from the near-infrared to the extreme ultraviolet, with an
emphasis on the ultraviolet long- and shortward of the Lyman break where most
of the stellar luminosity is emitted. Uncertainties in stellar atmosphere and
evolution models will be critically examined, and the impact on the total
panchromatic luminosity will be highlighted.


title: Self-consistent distance determinations for Lutz-Kelker-limited samples

abstract:
  We present a method designed to correct for Lutz-Kelker effects in
distance-limited samples. The method allows for the calculation of distances to
individual objects and, at the same time, provides a fit to a parameterized,
self-consistent spatial distribution of the population. An example using
Hipparcos data is presented and the relevance to Gaia is also discussed.


title:
Neutrino-Driven Supernovae: an Accretion Instability in a Nuclear
  Physics Controlled Environment

abstract:
  New simulations demonstrate that low-mode, nonradial hydrodynamic
instabilities of the accretion shock help starting hot-bubble convection in
supernovae and thus support explosions by the neutrino-heating mechanism. The
prevailing conditions depend on the high-density equation of state which
governs stellar core collapse, core bounce, and neutron star formation. Tests
of this sensitivity to nuclear physics variations are shown for spherically
symmetric models. Implications of current explosion models for r-process
nucleosynthesis are addressed.


title: Structure Function Analysis of Long Term Quasar Variability

abstract:
  In our second paper on long-term quasar variability, we employ a much larger
database of quasars than in de Vries, Becker & White. This expanded sample,
containing 35165 quasars from the Sloan Digital Sky Survey Data Release 2, and
6413 additional quasars in the same area of the sky taken from the 2dF QSO
Redshift Survey, allows us to significantly improve on our earlier conclusions.
As before, all the historic quasar photometry has been calibrated onto the SDSS
scale by using large numbers of calibration stars around each quasar position.
We find the following: (1) the outbursts have an asymmetric light-curve
profile, with a fast-rise, slow-decline shape; this argues against a scenario
in which micro-lensing events along the line-of-sight to the quasars are
dominating the long-term variations in quasars; (2) there is no turnover in the
Structure Function of the quasars up to time-scales of ~40 years, and the
increase in variability with increasing time-lags is monotonic and constant;
and consequently, (3) there is not a single preferred characteristic outburst
time-scale for the quasars, but most likely a continuum of outburst
time-scales, (4) the magnitude of the quasar variability is a function of
wavelength: variability increases toward the blue part of the spectrum, (5)
high-luminosity quasars vary less than low-luminosity quasars, consistent with
a scenario in which variations have limited absolute magnitude. Based on this,
we conclude that quasar variability is intrinsic to the Active Galactic
Nucleus, is caused by chromatic outbursts / flares with a limited luminosity
range and varying time-scales, and which have an overall asymmetric light-curve
shape. Currently the model that has the most promise of fitting the
observations is based on accretion disk instabilities.


title: Morphology, Environment, and the HI Mass Function

abstract:
  We exploit a large, complete optical diameter and HI flux limited sample of
spiral galaxies with types later than S0a to derive a robust measurement of the
HI mass function (HIMF) for masses log(M_HI/M_Sun) > 7.4 which takes into
account the effects of local large scale structure. The global HIMF derived for
this optically-selected sample is well fit by a Schechter function with alpha =
-1.24, log(M* / M_Sun)=9.99, phi* = 3.2 (10^{-3}) Mpc^{-3}. These values match
those derived from blind HI surveys to within the estimated uncertainties, yet
our estimated HIMF is clearly lower than most other estimates at the lowest
masses. We also investigate the variation in the derived HIMF among spiral
subclasses, finding a clear distinction between the Schechter parameters found
for types Sa-Sc and those Scd and later, in the sense that the HIMF of the
latest types is rising at the low mass end, whereas that of the main spiral
classes is flat or even declining. We also explore the possible environmental
dependence of the HIMF by computing it separately in regimes of differing
cosmic density. The HIMFs of higher density regions are found to have flatter
low-mass ends and lower values of M* than those of lower density regions,
although the statistical significance of the difference is low. We find that
the environmental dependence cannot be accounted for by morphological
segregation, and must be a consequence of differences among galaxies of the
same morphological type but found in different environments. If this dependence
is caused by the well known deficiency of galaxies in clusters, then it would
suggest that galaxies of small linear optical diameter are characterized by
higher HI deficiency, an expectation consistent with gas removal mechanisms
such as ram pressure stripping.


title: Methanol abundance in low mass protostars

abstract:
  Methanol lines observations of a sample of low mass Class 0 protostars are
presented. Using a 1D radiative transfer model, I show that several protostars
have large abundance jumps in the inner hot and dense region of envelopes,
probably because of thermal grain mantle evaporation. These abundances are
compared with a grain surface chemistry model.


title:
Positron annihilation spectrum from the Galactic Center region observed
  by SPI/INTEGRAL

abstract:
  The electron-positron annihilation spectrum observed by SPI/INTEGRAL during
deep Galactic Center region exposure is reported. The line energy
(510.954$\pm$0.075 keV) is consistent with the unshifted annihilation line. The
width of the annihilation line is 2.37$\pm$0.25 keV (FWHM), while the strength
of the ortho-positronium continuum suggests that the dominant fraction of
positrons (94$\pm$6%) form positronium before annihilation. Compared to the
previous missions these deep INTEGRAL observations provide the most stringent
constraints on the line energy and width.
  Under the assumption of an annihilation in a single-phase medium these
spectral parameters can be explained by a warm $T_e\sim 7000-4~10^4$ K gas with
the degree of ionization larger than a few $10^{-2}$. One of the wide-spread
ISM phases - warm ($T_e \sim 8000$ K) and weakly ionized (degree of ionization
$\sim$ 0.1) medium satisfies these criteria. Other single-phase solutions are
also formally allowed by the data (e.g. cold, but substantially ionized ISM),
but such solutions are believed to be astrophysically unimportant.
  The observed spectrum can also be explained by the annihilation in a
multi-phase ISM. The fraction of positrons annihilating in a very hot ($T_e \ge
10^6$ K) phase is constrained to be less than $\sim$8%. Neither a moderately
hot ($T_e \ge 10^5$ K) ionized medium nor a very cold ($T_e \le 10^3$ K)
neutral medium can make a dominant contribution to the observed annihilation
spectrum. However, a combination of cold/neutral, warm/neutral and warm/ionized
phases in comparable proportions could also be consistent with the data.


title: UV Morphology and Star Formation in the Tidal Tails of NGC 4038/39

abstract:
  We present GALEX FUV (1530 A) and NUV (2310 A) observations of the archetypal
merging system NGC 4038/39, ``The Antennae". Both tails are relatively bright
in the UV, especially in the vicinity of the Tidal Dwarf Galaxy candidates at
the end of the southern tail. The UV light generally falls within the optically
delineated tails, although the UV light is considerably more structured, with a
remarkably similar morphology to the tidal HI. The UV colors suggest that there
has been continuing star formation within the tidal tails, even outside the
previously studied Tidal Dwarf regions. Within the inner disk regions, there
are interesting UV features which appear to be related to the extended soft
X-ray loops and halo recently discovered by CHANDRA.


title:
The Moment of Inertia of the Binary Pulsar J0737-3039A: Constraining the
  Nuclear Equation of State

abstract:
  We construct numerical models of the newly discovered binary pulsar
J0737-3039A, both with a fully relativistic, uniformly rotating, equilibrium
code that handles arbitrary spins and in the relativistic, slow-rotation
approximation. We compare results for a representative sample of viable nuclear
equations of state (EOS) that span three, qualitatively different, classes of
models for the description of nuclear matter. A future dynamical measurement of
the neutron star's moment of inertia from pulsar timing data will impose
significant constraints on the nuclear EOS. Even a moderately accurate
measurement (<~ 10 %) may be able to rule out some of these competing classes.
Using the measured mass, spin and moment of inertia to identify the optimal
model computed from different EOSs, one can determine the pulsar's radius.


title:
New Constraints on the Star Formation Histories and Dust Attenuation of
  Galaxies in the Local Universe from GALEX

abstract:
  We derive a variety of physical parameters including star formation rates
(SFRs), dust attenuation and burst mass fractions for 6472 galaxies observed by
the Galaxy Evolution Explorer (GALEX) and present in the SDSS DR1 main
spectroscopic sample. Parameters are estimated in a statistical way by
comparing each observed broad-band SED (two GALEX and five SDSS bands) with an
extensive library of model galaxy SEDs, which cover a wide range of star
formation histories and include stochastic starbursts. We compare the
constraints derived using SDSS bands only with those derived using the
combination of SDSS and GALEX photometry. We find that the addition of the
GALEX bands leads to significant improvement in the estimation of both the dust
optical depth and the star formation rate over timescales of 100 Myr to 1 Gyr
in a galaxy. We are sensitive to SFRs as low as 10^{-3} M_sun/yr, and we find
that low levels of star formation (SF) are mostly associated with early-type,
red galaxies. The least massive galaxies have ratios of current to
past-averaged SF rates (b-parameter) consistent with constant SF over a Hubble
time. For late-type galaxies, this ratio on average decreases with mass. We
find that b correlates tightly with NUV-r color, implying that the SF history
of a galaxy can be constrained on the basis of the NUV-r color alone. The
fraction of galaxies that have undergone a significant starburst episode within
the last 1 Gyr steeply declines with mass-from ~20% for galaxies with ~10^8
M_sun to ~5% for ~10^11 M_sun galaxies.


title: X-rays from the First Massive Black Holes

abstract:
  We briefly review some recent results from Chandra and XMM-Newton studies of
the highest redshift (z > 4) active galactic nuclei (AGNs). Specific topics
covered include radio-quiet quasars, radio-loud quasars, moderate-luminosity
AGNs in X-ray surveys, and future prospects. No significant changes in AGN
X-ray emission properties have yet been found at high redshift, indicating that
the small-scale X-ray emission regions of AGNs are insensitive to the dramatic
changes on larger scales that occur from z = 0-6. X-ray observations are also
constraining the environments of high-redshift AGNs, relevant emission
processes, and high-redshift AGN demography.


title:
Systematics of the Ultraviolet Rising flux in a GALEX/SDSS sample of
  Early-type Galaxies

abstract:
  We present ultraviolet photometry for a sample of morphologically early-type
galaxies selected by matching the Sloan Digital Sky Survey Data Release 1 with
the GALEX Medium and All-sky Imaging Surveys. We obtain a working sample of
1032 early-type galaxies with GALEX FUV detections, SDSS spectroscopy, and
$z<0.2$. Using the SDSS spectra to identify galaxies with even weak star
formation or evidence of AGN, and further removing galaxies with any evidence
of non early-type morphology, we derive a final sample of 172 red quiescent
early-type galaxies. We find that the $FUV-r$ color has a full range of 5 mag.
Plotting against the $FUV-r$ color the metallicity sensitive Lick $\rm Mg_2$
and D4000 indices, and the stellar velocity dispersion, we find no correlation
between our measurement of UV rising flux, and any parameter sensitive to
metallicity.


title:
Spectroscopy of High-Redshift Supernovae from the ESSENCE Project: The
  First Two Years

abstract:
  We present the results of spectroscopic observations of targets discovered
during the first two years of the ESSENCE project. The goal of ESSENCE is to
use a sample of ~200 Type Ia supernovae (SNe Ia) at moderate redshifts (0.2 < z
< 0.8) to place constraints on the equation of state of the Universe.
Spectroscopy not only provides the redshifts of the objects, but also confirms
that some of the discoveries are indeed SNe Ia. This confirmation is critical
to the project, as techniques developed to determine luminosity distances to
SNe Ia depend upon the knowledge that the objects at high redshift are the same
as the ones at low redshift. We describe the methods of target selection and
prioritization, the telescopes and detectors, and the software used to identify
objects. The redshifts deduced from spectral matching of high-redshift SNe Ia
with low-redshift SNe Ia are consistent with those determined from host-galaxy
spectra. We show that the high-redshift SNe Ia match well with low-redshift
templates. We include all spectra obtained by the ESSENCE project, including 52
SNe Ia, 5 core-collapse SNe, 12 active galactic nuclei, 19 galaxies, 4 possibly
variable stars, and 16 objects with uncertain identifications.


title:
Direct WIMP Detection Using Scintillation Time Discrimination in Liquid
  Argon

abstract:
  Discrimination between electron and nuclear recoil events in a liquid argon
scintillation detector has been demonstrated with simulations by using the
differences in the scintillation photon time distribution between these classes
of events. A discrimination power greater than 10^{8} is predicted for a liquid
argon experiment with a 10 keV threshold, which would mitigate electron and
gamma-ray backgrounds, including beta decays of 39-Ar and 42-Ar in atmospheric
argon. A dark matter search using a ~2 kg argon target viewed by immersed
photomultiplier tubes would allow a sensitivity to a spin-independent
WIMP-nucleon cross-section of ~10^{-43} cm^{2} for a 100 GeV WIMP, assuming a
one-year exposure. This technique could be used to scale the target mass to the
tonne scale, allowing a sensitivity of ~10^{-46} cm^{2}.


title:
Disentangling Morphology, Star Formation, Stellar Mass, and Environment
  in Galaxy Evolution

abstract:
  We present a study of the spectroscopic and photometric properties of
galaxies in six nearby clusters. We perform a partial correlation analysis on
our dataset to investigate whether the correlation between star formation rates
in galaxies and their environment is merely another aspect of correlations of
morphology, stellar mass, or mean stellar age with environment, or whether star
formation rates vary independently of these other correlations. We find a
residual correlation of ongoing star formation with environment, indicating
that even galaxies with similar morphologies, stellar masses, and mean stellar
ages have lower star formation rates in denser environments. Thus, the current
star formation gradient in clusters is not just another aspect of the
morphology-density, stellar mass-density, or mean stellar age-density
relations. Furthermore, the star formation gradient cannot be solely the result
of initial conditions, but must partly be due to subsequent evolution through a
mechanism (or mechanisms) sensitive to environment. Our results constitute a
true ``smoking gun'' pointing to the effect of environment on the later
evolution of galaxies.


title:
Chandra HRC Localization of the Low Mass X-ray Binaries X1624-490 and
  X1702-429: The Infrared Counterparts

abstract:
  We report on the precise localization of the low mass X-ray binaries
X1624-490 and X1702-429 with the Chandra HRC-I. We determine the best positions
to be 16:28:02.825 -49:11:54.61 (J2000) and 17:06:15.314 -43:02:08.69 (J2000)
for X1624-490 and X1702-429, respectively, with the nominal Chandra positional
uncertainty of 0.6". We also obtained deep IR observations of the fields of
these sources in an effort to identify the IR counterparts. A single, faint
(Ks=18.3 +/- 0.1) source is visible inside the Chandra error circle of
X1624-490, and we propose this source as its IR counterpart. For X1702-429, a
Ks=16.5 +/- 0.07 source is visible at the edge of the Chandra error circle. The
brightness of both counterpart candidates is comparable to that of other low
mass X-ray binary IR counterparts when corrected for extinction and distance.


title: Gamma-Ray Bursts in the SALT/Swift Era: GRB/SN Connection

abstract:
  I discuss the Gamma Ray Burst research in the era of SALT and Swift,
concentrating on the GRB/SN connection.


title: Relativistic formulation and reference frame

abstract:
  After a short review of experimental foundations of metric theories of
gravity, the choice of general relativity as a theory to be used for the
routine modeling of Gaia observations is justified. General principles of
relativistic modeling of astronomical observations are then sketched and
compared to the corresponding Newtonian principles. The fundamental reference
system -- Barycentric Celestial Reference System, which has been chosen to be
the relativistic reference system underlying the future Gaia reference frame is
presented. Principal relativistic effects in each constituent of a relativistic
model of astronomical observations are briefly elucidated. The structure of a
relativistic model of positional observations which can be used as a standard
relativistic model for Gaia is sketched. The physical meaning of the Gaia
reference frame is discussed. It is discussed also how Gaia observations can be
used to verify general relativity.


title:
Refining the relativistic model for Gaia: cosmological effects in the
  BCRS

abstract:
  This paper represents a first attempt of embedding the Barycentric Celestial
Reference System, the fundamental relativistic reference system to be used for
the modeling of Gaia observations, into some cosmological background. The
general Robertson-Walker metric is transformed into local coordinates where the
cosmological effects are represented as tidal potentials. A version of a
cosmological BCRS is then suggested to lowest order. The effects of
cosmological background on the motion of the solar system are estimated and
found to be completely negligible. The relation to the de Sitter and
Schwarzschild-de Sitter solutions is discussed.


title: The UV Galaxy Luminosity Function in the Local Universe from GALEX Data

abstract:
  We present the results of a determination of the galaxy luminosity function
at ultraviolet wavelengths at redshifts of $z=0.0-0.1$ from GALEX data. We
determined the luminosity function in the GALEX FUV and NUV bands from a sample
of galaxies with UV magnitudes between 17 and 20 that are drawn from a total of
56.73 deg^2 of GALEX fields overlapping the b_j-selected 2dF Galaxy Redshift
Survey. The resulting luminosity functions are fainter than previous UV
estimates and result in total UV luminosity densities of 10^(25.55+/-0.12) ergs
s^-1 Hz^-1 Mpc^-3 and 10^(25.72+/-0.12) ergs s^-1 Hz^-1 Mpc^-3 at 1530 Ang. and
2310 Ang., respectively. This corresponds to a local star formation rate
density in agreement with previous estimates made with H-alpha-selected data
for reasonable assumptions about the UV extinction.


title:
Relationship between the gamma-ray burst pulse width and energy due to
  the Doppler effect of fireballs

abstract:
  We study in details how the pulse width of gamma-ray bursts is related with
energy under the assumption that the sources concerned are in the stage of
fireballs. Due to the Doppler effect of fireballs, there exists a power law
relationship between the two quantities within a limited range of frequency.
The power law range and the power law index depend strongly on the observed
peak energy $E_p$ as well as the rest frame radiation form, and the upper and
lower limits of the power law range can be determined by $E_p$. It is found
that, within the same power law range, the ratio of the $FWHM$ of the rising
portion to that of the decaying phase of the pulses is also related with energy
in the form of power laws. A platform-power-law-platform feature could be
observed in the two relationships. In the case of an obvious softening of the
rest frame spectrum, the two power law relationships also exist, but the
feature would evolve to a peaked one. Predictions on the relationships in the
energy range covering both the BATSE and Swift bands for a typical hard burst
and a typical soft one are made. A sample of FRED (fast rise and exponential
decay) pulse bursts shows that 27 out of the 28 sources belong to either the
platform-power-law-platform feature class or the peaked feature group,
suggesting that the effect concerned is indeed important for most of the
sources of the sample. Among these bursts, many might undergo an obvious
softening evolution of the rest frame spectrum.


title:
Observation of EGRET Gamma-Ray Sources by an Extensive Air Shower
  Experiment

abstract:
  Ultra-high-energy (E$>$100 Tev) Extensive Air Showers (EASs) have been
monitored for a period of five years (1997 - 2003), using a small array of
scintillator detectors in Tehran, Iran. The data have been analyzed to take in
to account of the dependence of source counts with respect to the zenith angle.
During a calendar year different sources come in the field of view of the
detector at varying zenith angles. Because of varying thickness of the
overlaying atmosphere, the shower count rate is extremely dependent on zenith
angle which have been carefully analyzed over time. High energy gamma-ray
sources from EGRET third catalogue where observed and the data were analyzed
using an excess method. A number of upper limits for a number of EGRET sources
were obtained, including 6 AGNs or probably AGNs and 4 unidentified sources.


title:
Ices in the edge-on disk CRBR 2422.8-3423: Spitzer spectroscopy and
  Monte Carlo radiative transfer modeling

abstract:
  We present 5.2-37.2 micron spectroscopy of the edge-on circumstellar disk
CRBR 2422.8-3423 obtained using the InfraRed Spectrograph (IRS) of the Spitzer
Space Telescope. The IRS spectrum is combined with ground-based 3-5 micron
spectroscopy to obtain a complete inventory of solid state material present
along the line of sight toward the source. We model the object with a 2D
axisymmetric (effectively 3D) Monte Carlo radiative transfer code. It is found
that the model disk, assuming a standard flaring structure, is too warm to
contain the very large observed column density of pure CO ice, but is possibly
responsible for up to 50% of the water, CO2 and minor ice species. In
particular the 6.85 micron band, tentatively due to NH4+, exhibits a prominent
red wing, indicating a significant contribution from warm ice in the disk. It
is argued that the pure CO ice is located in the dense core Oph-F in front of
the source seen in the submillimeter imaging, with the CO gas in the core
highly depleted. The model is used to predict which circumstances are most
favourable for direct observations of ices in edge-on circumstellar disks. Ice
bands will in general be deepest for inclinations similar to the disk opening
angle, i.e. ~70 degrees. Due to the high optical depths of typical disk
mid-planes, ice absorption bands will often probe warmer ice located in the
upper layers of nearly edge-on disks. The ratios between different ice bands
are found to vary by up to an order of magnitude depending on disk inclination
due to radiative transfer effects caused by the 2D structure of the disk.
Ratios between ice bands of the same species can therefore be used to constrain
the location of the ices in a circumstellar disk. [Abstract abridged]


title:
Relationship between different channel light curves of gamma-ray burst
  pulses shown in aspects other than the pulse width

abstract:
  In this paper, we employ the peak count rate{\bf \}$C_p$ and the total count
$C_{total}$ of light curves to study in the corresponding aspects the
relationship between different channel light curves. To make a direct
comparison between count rates of different channel light curves we introduce a
plot of $C(\tau)$ versus $C_H(\tau)$, where $C(\tau)$ is the count rate of a
channel and $C_H(\tau)$ is the count rate of a definite cannel, channel H (see
the text). According to the plot we define $\Delta C_{\max}$ as the maximum
deviation of the two count rate values of $C(\tau)$ associated with a same
count rate value of $% C_H(\tau)$ and define $\Delta S$ as the area confined by
the close curve of $C(\tau)$ in the plot to measure the difference of the
rising and decaying portions of a light curve relative to the count rate of
channel H. Under the assumption that some GRBs observed are in the stage of
fireballs which expand relativistically, predictions on the relationships
between the four quantities{\bf (}$C_p$, $C_{total}$, $\Delta C_{\max}$, and
$\Delta S$) and energy within a wide band, calculated with different rest frame
radiation forms and two typical Lorentz factors ($\Gamma =20$ and 200), are
made and presented, which would make the test of our model with the coming
Swift data easier. Interpretations to the relationships within the mechanism of
fireballs are also presented.


title:
Symmetry of the Neutron and Proton Superfluidity Effects in Cooling
  Neutron Stars

abstract:
  We investigate the combined effect of neutron and proton superfluidities on
the cooling of neutron stars whose cores consist of nucleons and electrons. We
consider singlet-state pairing of protons and triplet-state pairing of neutrons
in the cores of neutron stars. The critical superfluid temperatures T_c are
assumed to depend on the density of matter. We study two types of neutron
pairing with different components of the total angular momentum of Cooper pairs
along the quantization axis (|m_J| =0 or 2). Our calculations are compared with
observations of thermal emission from isolated neutron stars. We show that the
observations can be interpreted by using two classes of superfluidity models:
(1) strong proton superfluidity with a maximum critical temperature in the
stellar core T_c^{max} > 4 \times 10^9 K and weak neutron superfluidity of any
type (T_c^{max} < 2 \times 10^8 K); (2) strong neutron superfluidity (pairing
with |m_J|=0) and weak proton superfluidity. The two types of models reflect an
approximate symmetry with respect to an interchange of the critical
temperatures of neutron and proton pairing.


title: Models Of Strange Stars With A Crust And Strange Dwarfs

abstract:
  Strange quark stars with a crust and strange dwarfs consisting of a compact
strange quark core and an extended crust are investigated in terms of a bag
model. The crust, which consists of atomic nuclei and degenerate electrons, has
a limiting density of ro_ cr=ro_drip=4.3*10^11g/cm^3. A series of
configurations are calculated for two sets of bag model parameters and three
different values of ro_cr (10^9g/cm^3<=ro_cr<=ro_drip) to find the dependence
of a star's mass M and radius R on the central density. Sequences of stars
ranging from compact strange stars to extended strange dwarfs are constructed
out of strange quark matter with a crust. The effect of the bag model
parameters and limiting crust density ro_cr on the parameters of the strange
stars and strange dwarfs is examined. The strange dwarfs are compared with
ordinary white dwarfs and observational differences between the two are pointed
out.


title: Asteroseismology of sdB stars with FUSE

abstract:
  The hot subdwarf B (sdB) stars form an homogeneous group populating an
extension of the horizontal branch (HB) in the ($T_{\rm eff}$--$\log g$)
diagram towards temperatures up to 40,000 K. The recent discovery that many of
them are multimode pulsators has triggered a large observational and
theoretical effort. We discuss the possibility of performing space-based
asteroseismology with {\em FUSE}, and we demonstrate that periodic luminosity
variations are already detectable in archival TTAG data of sdB stars. In
particular, we report on the {\em FUSE} observation of the pulsator PF
1219+534, which shows the presence of periodic variations at 6.9 mHz and 7.8
mHz, consistent with those reported from ground--based observations.


title:
UV Emission from Stellar Populations within Tidal Tails: Catching the
  Youngest Galaxies in Formation?

abstract:
  New GALEX observations have detected significant FUV (1530 Angstroms) and NUV
(2310 Angstroms) emission from stellar substructures within the tidal tails of
four ongoing galaxy mergers. The UV-bright regions are optically faint and are
coincident with HI density enhancements. FUV emission is detected at any
location where the HI surface density exceeds ~2 M_sun pc^{-2}, and is often
detected in the absence of visible wavelength emission. UV luminosities of the
brighter regions of the tidal tails imply masses of 10^6 M_sun to ~10^9 M_sun
in young stars in the tails, and HI luminosities imply similar HI masses.
UV-optical colors of the tidal tails indicate stellar populations as young as a
few Myr, and in all cases ages < 400Myr. Most of the young stars in the tails
formed in single bursts rather than resulting from continuous star formation,
and they formed *in situ* as the tails evolved. Star formation appears to be
older near the parent galaxies and younger at increasing distances from the
parent galaxy. This could be because the star formation occurs progressively
along the tails, or because the star formation has been inhibited near the
galaxy/tail interface. The youngest stellar concentrations, usually near the
ends of long tidal tails, have masses comparable to confirmed tidal dwarf
galaxies and may be newly forming galaxies undergoing their first burst of star
formation.


title: Relativistic Particle Acceleration in a Folded Current Sheet

abstract:
  Two-dimensional particle simulations of a relativistic Harris current sheet
of pair plasmashave demonstrated that the system is unstable to the
relativistic drift kink instability (RDKI) and that a new kind of acceleration
process takes place in the deformed current sheet. This process contributes to
the generation of non-thermal particles and contributes to the fast magnetic
dissipation in the current sheet structure. The acceleration mechanism and a
brief comparison with relativistic magnetic reconnection are presented.


title: K-shell Photoabsorption of Oxygen Ions

abstract:
  Extensive calculations of the atomic data required for the spectral modelling
of the K-shell photoabsorption of oxygen ions have been carried out in a
multi-code approach. The present level energies and wavelengths for the highly
ionized species (electron occupancies 2 <= N <= 4) are accurate to within 0.5
eV and 0.02 A, respectively. For N > 4, lack of measurements, wide experimental
scatter, and discrepancies among theoretical values are handicaps in reliable
accuracy assessments. The radiative and Auger rates are expected to be accurate
to 10% and 20%, respectively, except for transitions involving strongly mixed
levels. Radiative and Auger dampings have been taken into account in the
calculation of photoabsorption cross sections in the K-threshold region,
leading to overlapping lorentzian shaped resonances of constant widths that
cause edge smearing. The behavior of the improved opacities in this region has
been studied with the XSTAR modelling code using simple constant density slab
models, and is displayed for a range of ionization parameters.


title: Extinction radial profiles of M83 from GALEX UV imaging

abstract:
  We use the far-UV (FUV) and near-UV (NUV) images of M83 obtained by GALEX to
compute the radial profile of the UV spectral slope in the star forming disk.
We briefly present a model of its chemical evolution which allows us to obtain
realistic intrinsic properties of the stellar populations. Using corollary
data, we also compute the profiles of H-alpha/H-beta and of the total IR (TIR)
to FUV ratio. Both data and model are used to estimate and compare the
extinction gradients at the FUV wavelength obtained from these various
indicators. We discuss the implications for the determination of the star
formation rate.


title:
Limits of dark energy measurements from CMB lensing-ISW-galaxy count
  correlations

abstract:
  I discuss several issues that arise when trying to constrain the dark energy
equation of state using correlations of the integrated Sachs-Wolfe effect with
galaxy counts and lensing of the cosmic microwave background. These techniques
are complementary to others such as galaxy shear surveys, and can use data that
will already be obtained from currently planned observations. In regimes where
cosmic variance and shot noise are the dominant sources of error, constraints
could be made on the mean equation of state to within 0.33 and its first
derivative to within 1.0. Perhaps more interesting is that the determination of
dark energy parameters by these types of experiments depends strongly on the
presence or absence of perturbations in the dark energy fluid.


title:
White Dwarf Light Curves: Constraining Convection and Mode
  Identification Using Non-sinusoidal Light Curves

abstract:
  In this paper we show how the formalism of Wu & Goldreich developed for
weakly nonlinear white dwarf pulsations can be extended to the fully nonlinear
case. Due to the computational simplification this affords over the simulations
of Brickhill (1992) and Ising & Koester (2001), we are able to obtain the first
ever fits of observed light curves. These fits allow us to obtain not only mode
identifications but also to constrain the average depth of the convection zone
and its sensitivity to changes in effective temperature. We are thus able to
probe the fundamental physics of convection in these objects.


title: Compton Scattering of Fe K\alpha Lines from Accreting White Dwarfs

abstract:
  Compton scattering in the bulk accretion flow of the accretion column in
magnetic cataclysmic variables (mCVs) can significantly shift photon energies
in the X-ray emission lines resulting from accretion shocks. In particular,
Compton recoil can potentially broaden the 6.7 and 6.97 keV Fe K$\alpha$
emission lines produced in the post-shock region, and contaminate the
fluorescent 6.4 keV neutral Fe K$\alpha$ line reflected off the white dwarf
surface. We present nonlinear Monte Carlo simulations demonstrating these
effects, and we discuss the interpretation of observed Fe K$\alpha$ linewidths
in mCVs in light of these new results. The implications for other accreting
compact objects are also discussed.


title: Formation of a spiral galaxy in a major merger

abstract:
  We use numerical simulations to examine the structure of merger remnants
resulting from collisions of gas-rich spiral galaxies. When the gas fraction of
the progenitors is small, the remnants structurally and kinematically resemble
elliptical galaxies, in agreement with earlier work. However, if the progenitor
disks are gas-dominated, new types of outcomes are possible. In fact, we show
that a prominent disk may survive in certain cases. To illustrate this
scenario, we analyze an extreme example with progenitor galaxies consisting of
dark matter halos, pure gas disks, and no bulges, as might be appropriate for
mergers at high redshifts. While rapid star formation triggered by tidal
torques during the merger forms a central, rotating bulge in the remnant, not
all the gas is consumed in the burst. The remaining gas cools very quickly and
settles into an extended star-forming disk, yielding an object similar to a
spiral galaxy, and not an early type galaxy. This is contrary to the usual view
that major mergers invariably destroy disks. The morphological evolution of
galaxies can therefore be more complicated than often assumed, and in
particular, theoretical constraints based on the fragility of spiral disks need
to be reevaluated.


title: FUSE and the Astrophysics of AGN and QSOs

abstract:
  The high spectral resolution and sensitivity of FUSE have enabled
far-ultraviolet studies of AGN and QSOs that are a natural complement to
observations using HST, Chandra, and XMM-Newton. Through synergistic use of the
large sample of nearby AGN that serve as background probes of gas in the
Galactic halo and the ISM, the FUSE PI team has observed a large number
(approaching 100) of the nearest and brightest AGN. In addition to emission
from O VI, we identify emission lines due to C III, N III, S IV, and He II in
many of the Type-1 AGN. More than half of the Type 1 objects also show
intrinsic absorption by the O VI doublet as well as C IV absorption and
evidence of a soft X-ray warm absorber. Guest investigators have successfully
coordinated FUSE observations of bright AGN with simultaneous HST and X-ray
observations. These have contributed greatly to our understanding of the UV and
X-ray absoring gas in AGN as either a wind from the accretion disk, or a
thermally driven wind from the obscuring torus.


title: Search for Aligned Events in Muon Groups Measured by BUST

abstract:
  A search for aligned events has been done throughout the muon groups events
measured by Baksan Underground Scintillation Telescope (BUST) during a period
of 7.7 years. Only groups of multiplicity $>3$ for muon threshold energy equal
to 0.85 TeV were selected for the analysis. A distribution of the events on
alignment parameter $\lambda$ has been obtained and compared with the results
of Monte-Carlo simulation made for this experiment. The upper limit for aligned
muon event flux as low as $5.3\cdot10^{-15}$ $cm^{-2} sec^{-1} sr^{-1}$ is
given.


title: A Formation Scenario for the Heavy-Weight Cluster W3 in NGC 7252

abstract:
  The young star cluster W3 (age 300-500 Myr) in NGC 7252 is the most luminous
star cluster known to date. Dynamical mass estimates result in 8 +/- 2 * 10^7
M_sun. With an effective radius of about 18 pc and a velocity dispersion of 45
km/s this object is rather one of the recently discovered ultra-compact dwarf
(UCD) galaxies than a star cluster. In our model we propose a formation
scenario for W3. Observations of interacting galaxies reveal regions of strong
star formation forming dozens up to hundreds of star clusters in confined
regions of several hundred parsec in diameter. The total mass of new stars in
these regions can reach 10^7 or even 10^8 solar masses. By means of numerical
simulations we have shown that the star clusters in these regions merge on
short time-scales forming objects like UCD galaxies or W3.


title: Towards simulating star formation in the interstellar medium

abstract:
  As a first step to a more complete understanding of the local physical
processes which determine star formation rates (SFRs) in the interstellar
medium (ISM), we have performed controlled numerical experiments consisting of
hydrodynamical simulations of a kilo-parsec scale, periodic, highly supersonic
and "turbulent" three-dimensional flow. Using simple but physically motivated
recipes for identifying star forming regions, we convert gas into stars which
we follow self-consistently as they impact their surroundings through
supernovae and stellar winds. We investigate how various processes (turbulence,
radiative cooling, self-gravity, and supernovae feedback) structure the ISM,
determine its energetics, and consequently affect its SFR. We find that the
one-point statistical measurement captured by the probability density function
(PDF) is sensitive to the simulated physics. Aside from its effect on the
density structure of the medium, including self-gravity and/or supernovae
feedback changes the dynamics of the medium by halting the decay of the kinetic
energy. Since we find that the SFR depends most strongly on the underlying
velocity field, the SFR declines in the runs lacking a means to sustain the
kinetic energy, and the subsequent high density constrasts. This strong
dependence on the gas velocity dispersion is in agreement with Silk's formula
for the SFR (Silk 2001) which also takes the hot gas porosity, and the average
gas density as important parameters. Measuring the porosity of the hot gas for
the runs with supernovae feedback, we compare Silk's model for the SFR to our
measured SFR and find agreement to better than a factor two.


title: Atmospheric Refraction Path Integrals in Ground-Based Interferometry

abstract:
  The basic effect of the earth's atmospheric refraction on telescope operation
is the reduction of the true zenith angle to the apparent zenith angle,
associated with prismatic aberrations due to the dispersion in air. If one
attempts coherent superposition of star images in ground-based interferometry,
one is in addition interested in the optical path length associated with the
refracted rays. In a model of a flat earth, the optical path difference between
these is not concerned as the translational symmetry of the setup means no net
effect remains.
  Here, I evaluate these interferometric integrals in the more realistic
arrangement of two telescopes located on the surface of a common earth sphere
and point to a star through an atmosphere which also possesses spherical
symmetry. Some focus is put on working out series expansions in terms of the
small ratio of the baseline over the earth radius, which allows to bypass some
numerics which otherwise is challenged by strong cancellation effects in
building the optical path difference.


title:
Low-Luminosity Accretion in Black Hole X-ray Binaries and Active
  Galactic Nuclei

abstract:
  At luminosities below a few percent of Eddington, accreting black holes
switch to a hard spectral state which is very different from the soft
blackbody-like spectral state that is found at higher luminosities. The hard
state is well-described by a two-temperature, optically thin, geometrically
thick, advection-dominated accretion flow (ADAF) in which the ions are
extremely hot (up to $10^{12}$ K near the black hole), the electrons are also
hot ($\sim10^{9-10.5}$ K), and thermal Comptonization dominates the X-ray
emission. The radiative efficiency of an ADAF decreases rapidly with decreasing
mass accretion rate, becoming extremely low when a source reaches quiescence.
ADAFs are expected to have strong outflows, which may explain why relativistic
jets are often inferred from the radio emission of these sources. It has been
suggested that most of the X-ray emission also comes from a jet, but this is
less well established.


title:
A VLT spectroscopic survey of RX J0152.7-1357, a forming cluster of
  galaxies at z=0.837

abstract:
  We present the results of an extensive spectroscopic survey of RX
J0152.7-1357, one of the most massive distant clusters of galaxies known.
Multi-object spectroscopy, carried out with FORS1 and FORS2 on the ESO Very
Large Telescope (VLT), has allowed us to measure more than 200 redshifts in the
cluster field and to confirm 102 galaxies as cluster members. The mean redshift
of the cluster is $z=0.837 \pm 0.001$ and we estimate the velocity dispersion
of the overall cluster galaxy distribution to be $\sim 1600 \mathrm{km \
s^{-1}}$. The distribution of cluster members is clearly irregular, with two
main clumps that follow the X-ray cluster emission mapped by Chandra. A third
clump of galaxies to the east of the central structure and at the cluster
redshift has also been identified. The two main clumps have velocity
dispersions of $\sim919$ and $\sim737 \mathrm{km s^{-1}}$ respectively, and the
peculiar velocity of the two clumps suggests that they will merge into a single
more massive cluster. A segregation in the star formation activity of the
member galaxies is observed. All star forming galaxies are located outside the
high-density peaks, which are populated only by passive galaxies. A population
of red galaxies (belonging to the cluster red sequence) with clear
post-starburst spectral features and [OII] ($\lambda$3727) emission lines is
observed in the outskirts of the cluster. Two AGNs, which were previously
confused with the diffuse X-ray emission from the intracluster medium in ROSAT
and BeppoSAX observations, are found to be cluster members.


title: Integrating Existing Software Toolkits into VO System

abstract:
  Virtual Observatory (VO) is a collection of interoperating data archives and
software tools. Taking advantages of the latest information technologies, it
aims to provide a data-intensively online research environment for astronomers
all around the world.
  A large number of high-qualified astronomical software packages and libraries
are powerful and easy of use, and have been widely used by astronomers for many
years. Integrating those toolkits into the VO system is a necessary and
important task for the VO developers.
  VO architecture greatly depends on Grid and Web services, consequently the
general VO integration route is "Java Ready - Grid Ready - VO Ready". In the
paper, we discuss the importance of VO integration for existing toolkits and
discuss the possible solutions. We introduce two efforts in the field from
China-VO project, "gImageMagick" and " Galactic abundance gradients statistical
research under grid environment". We also discuss what additional work should
be done to convert Grid service to VO service.


title: Efficiency of the dynamical mechanism

abstract:
  The most extreme starbursts occur in galaxy mergers, and it is now
acknowledged that dynamical triggering has a primary importance in star
formation. This triggering is due partly to the enhanced velocity dispersion
provided by gravitational instabilities, such as density waves and bars, but
mainly to the radial gas flows they drive, allowing large amounts of gas to
condense towards nuclear regions in a small time scale. Numerical simulations
with several gas phases, taking into account the feedback to regulate star
formation, have explored the various processes, using recipes like the Schmidt
law, moderated by the gas instability criterion. May be the most fundamental
parameter in starbursts is the availability of gas: this sheds light on the
amount of external gas accretion in galaxy evolution. The detailed mechanisms
governing gas infall in the inner parts of galaxy disks are discussed.


title: The Duty-cycle of Gamma-ray Blazars: a New Approach, New Results

abstract:
  We study several properties of blazars detected in the gamma-ray energy range
by comparing the EGRET sources with a sample of radio blazars which can be
considered possible gamma-ray candidates. We define three classes:
non-gamma-ray blazars, blazars with quasi-steady gamma-ray emission, and
gamma-ray blazars with substantial activity level. By combining the information
of detected and candidate AGNs, we characterise the blazar activity, including
the discovery of a region of consistency between the gamma-ray flaring
duty-cycle and the recurrence time between flares. We also find a possible
relation between the activity index of FSRQs and their black hole mass.


title: GALEX UV Spectroscopy and Deep Imaging of LIRGs in the ELAIS S1 field

abstract:
  The ELAIS S1 field was observed by GALEX in both its Wide Spectroscopic and
Deep Imaging Survey modes. This field was previously observed by the Infrared
Space Observatory and we made use of the catalogue of multi-wavelength data
published by the ELAIS consortium to select galaxies common to the two samples.
Among the 959 objects with GALEX spectroscopy, 88 are present in the ELAIS
catalog and 19 are galaxies with an optical spectroscopic redshift. The
distribution of redshifts covers the range $0<z<1.6$. The selected galaxies
have bolometric IR luminosities $10<Log(L_{IR})<13$ (deduced from the $15 \mu
m$ flux using ISOCAM) which means that we cover a wide range of galaxies from
normal to Ultra Luminous IR Galaxies. The mean ($\sigma$) UV luminosity (not
corrected for extinction) amounts to $Log(\lambda.L_{1530}) = 9.8 (0.6)$
$L_\sun$ for the low-z ($z \le 0.35$) sample. The UV slope $\beta$ (assuming
$f_\lambda \propto \lambda^\beta$) correlates with the GALEX FUV-NUV color if
the sample is restricted to galaxies below $z < 0.1$. Taking advantage of the
UV and IR data, we estimate the dust attenuation from the IR/UV ratio and
compare it to the UV slope $\beta$. We find that it is not possible to uniquely
estimate the dust attenuation from $\beta$ for our sample of galaxies. These
galaxies are highly extinguished with a median value $A_{FUV} = 2.7 \pm 0.8$.
Once the dust correction applied, the UV- and IR-based SFRs correlate. For the
closest galaxy with the best quality spectrum, we see a feature consistent with
being produced by a bump near 220nm in the attenuation curve.


title:
The GALEX-VVDS Measurement of the Evolution of the 1500A Luminosity
  Function

abstract:
  We present the first measurement of the galaxy luminosity function at 1500A
between 0.2<z<1.2 based on GALEX-VVDS observations (1000 spectroscopic
redshifts for galaxies with NUV<24.5) and at higher z using existing datasets.
Our main results are summarized as follows :
  (i) luminosity evolution is observed with Delta(Mstar)=-2.0 mag between z=0
and z=1 and Delta(Mstar)=-1.0mag between z=1 and z=3. This confirms that the
star formation activity was significantly higher in the past.
  (ii) the LF slopes vary between -1.2< alpha <-1.65, with a marginally
significant hint of increase at higher z.
  (iii) we split the sample in three restframe (B-I) intervals providing an
approximate spectral type classification: Sb-Sd, Sd-Irr and unobscured
starbursts. We find that the bluest class evolves less strongly in luminosity
than the two other classes. On the other hand their number density increases
sharply with z (15% in the local universe to 55% at z=1) while that of the
reddest classes decreases.


title: The early phases of Milky Way's chemical evolution

abstract:
  The earliest phases of the chemical evolution of our Galaxy are analysed in
the light of the recent VLT results (concerning abundance patterns in the most
metal-poor stars of the Galactic halo) and of stellar nucleosynthesis
calculations. It is argued that: 1) the unexpected abundance patterns observed
in Pop. II stars are not the imprints of an early generation of supermassive
Pop. III stars; 2) among the various suggestions made to exlain the observed
abundance patterns, nucleosynthesis in asymmetric supernova explosions appears
most promising. In the latter case, an indirect correlation between asymmetry
and metallicity is suggested by the data. Finally, the VLT data confirm two old
``puzzles'': the existence of primary N early in Galaxy's evolution (which
constrains the mixing of protons with He-burning products in massive stars) and
the absence of dispersion in abundance ratios, at least up to the Fe peak, in
the early Galaxy (which bears on the timescales of homogeneisation of the
interstellar medium, but also on yield variations among massive stars).


title: On the nature of the hydrodynamic stability of accretion disks

abstract:
  The linear stability of accretion disks is revisited. The governing equations
are expanded asymptotically and solved to first order in the expansion
parameter $\epsilon$ defined by the ratio of the disk's vertical thickness to
its radial extent. Algebraically growing solutions are found for global
perturbations on the radial accretion flow of thin inviscid compressible
Keplerian disks. The algebraic temporal behavior is exhibited in the vertical
velocities and the thermodynamic variables and has the form $t\sin\Omega_0 t$
locally in the disk where $\Omega_0$ is the Keplerian rotation rate. The
physical implications and relations to the Solberg-Hoiland stability criteria
are discussed.


title: Non-Gaussianity from Preheating

abstract:
  We consider a two-field model for inflation where the second order metric
perturbations can be amplified by a parametric resonance during preheating. We
demonstrate that there can arise a considerable enhancement of non-Gaussianity
sourced by the local terms generated through the coupled perturbations. We
argue that the non-Gaussianity parameter could be as large as f_{NL} ~ 50. Our
results may provide a useful test of preheating in future CMB experiments.


title: Astroparticle yield and transport from extragalactic jet terminal shocks

abstract:
  The present paper deals with the yield and transport of high-energy particle
within extragalactic jet terminal shocks, also known as hotspots. We
investigate in some details the cosmic ray, neutrinos and high-energy photons
yield in hotspots of powerful FRII radio-galaxies by scanning all known spatial
transport regimes, adiabatic and radiative losses as well as Fermi acceleration
process. Since both electrons and cosmic rays are prone to the same type of
acceleration, we derive analytical estimates of the maximal cosmic ray energy
attainable in both toroidal and poloidal magnetic field dominated shock
structures by using observational data on synchrotron emission coming from
various hot-spots. One of our main conclusions is that the best hot-spot
candidates for high energy astroparticle production is the extended
($L_{HS}\geq 1kpc$), strongly magnetized ($B> 0.1mG$) terminal shock displaying
synchrotron emission cut-off lying at least in the optical band. We found only
one object (3C273A) over the six objects in our sample being capable to produce
cosmic rays up to $10^{20}$ eV. Secondly, we investigate the astroparticle
spectra produced by two characteric hot-spots (Cygnus A and 3C273 A) by
applying a multi-scale MHD-kinetic scheme, coupling MHD simulations to kinetic
computations using stochastic differential equations. We show that 3C273 A,
matching the previous properties, may produce protons up to $10^{20}$ eV in a
Kolmogorov type turbulence by both computing electron and cosmic ray
acceleration. We also calculate the high-energy neutrino and gamma-ray fluxes
on Earth produced through p-$\gamma$ and p-p processes and compare them to the
most sensitive astroparticle experiments.


title: The CRESST Dark Matter Search

abstract:
  We present first competitive results on WIMP dark matter using the
phonon-light-detection technique. A particularly strong limit for WIMPs with
coherent scattering results from selecting a region of the phonon-light plane
corresponding to tungsten recoils. The observed count rate in the neutron band
is compatible with the rate expected from neutron background. CRESST is
presently being upgraded with a 66 channel SQUID readout system, a neutron
shield and a muon veto system. This results in a significant improvement in
sensitivity.


title:
The Stellar Content of Obscured Galactic Giant HII Regions V:
  G333.1--0.4

abstract:
  We present high angular resolution near--infrared images of the obscured
Galactic Giant HII (GHII) region G333.1--0.4 in which we detect an OB star
cluster. For G333.1--0.4, we find OB stars and other massive objects in very
early evolutionary stages, possibly still accreting. We obtained $K$--band
spectra of three stars; two show O type photospheric features, while the third
has no photospheric features but does show CO 2.3 $\mu$m band--head emission.
This object is at least as hot as an early B type star based on its intrinsic
luminosity and is surrounded by a circumstellar disc/envelope which produces
near infrared excess emission. A number of other relatively bright cluster
members also display excess emission in the $K$--band, indicative of
disks/envelopes around young massive stars. Based upon the O star photometry
and spectroscopy, the distance to the cluster is 2.6 $\pm$ 0.4 kpc, similar to
a recently derived kinematic (near side) value. The slope of the $K$--band
luminosity function is similar to those found in other young clusters. The mass
function slope is more uncertain, and we find $-1.3 \pm 0.2 < \Gamma < -1.1 \pm
0.2$- for stars with M $> 5$ M$_\odot$ where the upper an lower limits are
calculated independently for different assumptions regarding the excess
emission of the individual massive stars. The number of Lyman continuum photons
derived from the contribution of all massive stars in the cluster is 0.2
$\times$ $10^{50}$ $s^{-1}$ $< NLyc < 1.9$ $\times$ $10^{50}$ $s^{-1}$. The
integrated cluster mass is 1.0 $\times$ $10^{3}$ $M_\odot < M_{cluster} < 1.3$
$\times$ $10^{3}$ $M_\odot$.


title:
Atmospheric NLTE-Models for the Spectroscopic Analysis of Blue Stars
  with Winds. II. Line-Blanketed Models

abstract:
  We present new or improved methods for calculating NLTE, line-blanketed model
atmospheres for hot stars with winds (spectral types A to O), with particular
emphasis on a fast performance. These methods have been implemented into a
previous, more simple version of the model atmosphere code FASTWIND
(Santolaya-Rey et al.1997) and allow to spectroscopically analyze rather large
samples of massive stars in a reasonable time-scale, using state-of-the-art
physics.
  We describe our (partly approximate) approach to solve the equations of
statistical equilibrium for those elements which are primarily responsible for
line-blocking and blanketing, as well as an approximate treatment of the
line-blocking itself, which is based on a simple statistical approach using
suitable means for line opacities and emissivities. Furthermore, we comment on
our implementation of a consistent temperature structure.
  In the second part, we concentrate on a detailed comparison with results from
those two codes which have been used in alternative spectroscopical
investigations, namely CMFGEN (Hillier & Miller 1998) and WM-Basic (Pauldrach
et al. 2001). All three codes predict almost identical temperature structures
and fluxes for lambda > 400 A, whereas at lower wavelengths a number of
discrepancies are found. Optical H/He lines as synthesized by FASTWIND are
compared with results from CMFGEN, obtaining a remarkable coincidence, except
for the HeI singlets in the temperature range between 36,000 to 41,000 K for
dwarfs and between 31,000 to 35,000 K for supergiants, where CMFGEN predicts
much weaker lines. Consequences due to these discrepancies are discussed.


title:
Sunyaev-Zeldovich effects, free-free emission, and imprints on the
  cosmic microwave background

abstract:
  The signatures from Sunyaev-Zeldovich effects and free-free emission in the
intergalactic and intracluster medium and at galactic scales probe the
structure evolution at various cosmic times. The detection of these sources
and, possibly, the precise imaging of their spatial structure at the high
resolution and sensitivity achievable with SKA will greatly contribute to the
comprehension of crucial cosmological and astrophysical aspects, as the
physical conditions of early ionized halos, quasars and proto-galactic gas and
the mapping of the thermal and density structure of clusters of galaxies, with
an extremely accurate control of extragalactic radio sources, which represents
also a useful by-product for future CMB spectrum experiments devoted to probe
the thermal plasma history at early times.


title: Propagation of cosmic rays: nuclear physics in cosmic-ray studies

abstract:
  The nuclei fraction in cosmic rays (CR) far exceeds the fraction of other CR
species, such as antiprotons, electrons, and positrons. Thus the majority of
information obtained from CR studies is based on interpretation of isotopic
abundances using CR propagation models where the nuclear data and isotopic
production cross sections in p- and alpha-induced reactions are the key
elements. This paper presents an introduction to the astrophysics of CR and
diffuse gamma rays and discusses some of the puzzles that have emerged recently
due to more precise data and improved propagation models. Merging with
cosmology and particle physics, astrophysics of CR has become a very dynamic
field with a large potential of breakthrough and discoveries in the near
future. Exploiting the data collected by the CR experiments to the fullest
requires accurate nuclear cross sections.


title:
The Dwarf LSB Galaxy Population of the Virgo Cluster II. Colours and HI
  line observations

abstract:
  In order to investigate the nature of dwarf Low Surface Brightness (LSB)
galaxies we have undertaken a deep B and I band CCD survey of a 14 sq degree
strip in the Virgo Cluster and applied a Fourier convolution technique to
explore its dwarf galaxy population down to a central surface brightness of 26
B mag/sq arcsec and a total absolute B mag of ~ -10. In this paper we carry out
an analysis of their morphology, (B-I) colours and atomic hydrogen content. We
compare these properties with those of dwarf galaxies in other environments to
try and assess how the cluster environment has influenced their evolution.
Field dwarfs are generally of a more irregular morphology, are bluer and
contain relatively more gas. We assess the importance that various physical
processes have on the evolution of cluster dwarf galaxies (ram pressure
stripping, tidal interactions, supernova driven gas loss). We suggest that
enhanced star formation triggered by tidal interactions is the major reason for
the very different general properties of cluster dwarfs: they have undergone
accelerated evolution.


title: Polarization and energy content of parsec scale AGN jets

abstract:
  Most of energy carried by relativistic AGN jets remains undetected until
hundreds of kiloparsecs where interaction with intergalactic medium produces
hot spots. The jet's hidden energy is only partially dissipated at smaller
scales, from parsecs to kiloparsecs. Several media may play the role of the
``prime mover'': ions, pairs or large scale magnetic fields. Analyzing VLBI
polarization structures of relativistic parsec scale jets we conclude that
large-scale magnetic fields can explain the salient polarization properties of
parsec-scale AGN jets. This implies that large-scale magnetic fields carry a
non-negligible fraction of jet luminosity. We also discuss the possibility that
relativistic AGN jets may be electromagnetically (Poynting flux) dominated. In
this case, dissipation of the toroidal magnetic field (and not fluid shocks)
may be responsible for particle acceleration.


title:
HST and FUSE Spectroscopy of Hot Hydrogen-Rich Central Stars of
  Planetary Nebulae

abstract:
  High-resolution UV spectra, obtained with HST and FUSE, enable us to analyse
hot hydrogen-rich central stars in detail. Up to now, optical hydrogen and
helium lines have been used to derive temperature and surface gravity. Those
lines, however, are rather insensitive; in particular, neutral helium lines
have completely vanished in the hottest central stars. Therefore, we have
concentrated on ionization balances of metals, which have a rich line spectrum
in the UV, to establish a new temperature scale for our sample. Furthermore, we
have determined abundances of light metals, which had been poorly known before.
They show considerable variation from star to star. We present results of
quantitative spectral analyses performed with non-LTE model atmospheres.


title: Iron Abundance in Hydrogen-Rich Central Stars of Planetary Nebulae

abstract:
  We report on an on-going analysis of high-resolution UV spectra of hot
hydrogen-rich central stars of planetary nebulae (CSPN), obtained with the
Hubble Space Telescope and FUSE. Since UV spectra of many CSPN are dominated by
Fe and Ni lines, we intend to use them as temperature indicators to check the
CSPN temperature scale we have derived earlier from CNO ionization balances.
Furthermore, the observed line strengths of heavy metals show large variations
between different objects suggesting a possible spread in abundances. We will
determine abundances of iron group elements by quantitative spectral analyses
with non-LTE model atmospheres.


title: Star Formation in Three Nearby Galaxy Systems

abstract:
  We present an analysis of the distribution and strength of star formation in
three nearby small galaxy systems, which are undergoing a weak interaction, a
strong interaction, and a merging process, respectively. The galaxies in all
systems present widespread star formation enhancements,as well as, in some
cases, nuclear activity. In particular, for the two closest systems, we study
the number-count, size, and luminosity distribution of H {\sc ii} regions
within the interacting galaxies, while for the more distant, merging system we
analyze the general distribution of the Halpha emission across the system and
its velocity field.


title:
Classification and Characterization of Objects from GALEX and SDSS
  surveys

abstract:
  We use the GALEX (Galaxy Evolution Explorer) Medium Imaging Survey (MIS) and
All-Sky Imaging Survey (AIS) data available in the first internal release,
matched to the SDSS catalogs in the overlapping regions, to classify objects by
comparing the multi-band photometry to model colors. We show an example of the
advantage of such broad wavelength coverage (GALEX far-UV and near-UV, SDSS
ugriz) in classifying objects and augmenting the existing samples and catalogs.
  From the MIS [AIS] sample over an area of 75 [92] square degrees, we select a
total of 1736 [222] QSO candidates at redshift less than 2, significantly
extending the number of fainter candidates, and moderately increasing the
number of bright objects in the SDSS list of spectroscopically confirmed QSO.
  Numerous hot stellar objects are also revealed by the UV colors, as expected.


title: X-ray luminosity function of low-mass X-ray binaries in galaxies

abstract:
  X-ray luminosity function derived from observations of X-ray sources in
galactic bulges can be explained by prinicipal evolutionary relations for mass
accretion rate onto the compact object. The observed mean distribution of
individual X-ray luminosities of galactic LMXB is satisfactorily described by a
symmetric quasi-Lorentzian curve. The flux variance for bright sources is found
to be proportional to the mean luminosity. Such a distribution does not change
the slope of the power law luminosity function of the source population, which
is expected from the dependence of the mass transfer rate on the mass of the
Roche-lobe filling non-degenerate optical component.


title: Recent star formation in nearby galaxies from GALEX imaging:M101 and M51

abstract:
  The GALEX (Galaxy Evolution Explorer) Nearby Galaxies Survey is providing
deep far-UV and near-UV imaging for a representative sample of galaxies in the
local universe. We present early results for M51 and M101, from GALEX UV
imaging and SDSS optical data in five bands. The multi-band photometry of
compact stellar complexes in M101 is compared to population synthesis models,
to derive ages, reddening, reddening-corrected luminosities and current/initial
masses. The GALEX UV photometry provides a complete census of young compact
complexes on a approximately 160pc scale. A galactocentric gradient of the
far-UV - near-UV color indicates younger stellar populations towards the outer
parts of the galaxy disks, the effect being more pronounced in M101 than in
M51.


title: Weighing the Dark Matter Halo

abstract:
  The dark matter problem will be solved only when all of the dark matter is
accounted for. Although wimps may be discovered in direct detection experiments
soon, we will not know what fraction of the dark matter halo they compose until
we measure their local density. In this talk, I will offer a novel method to
determine the mass of a wimp from direct detection experiments alone using
kinematical consistency constraints. I will then describe a general method to
estimate the local density of wimps using both dark matter detection and hadron
collider data when it becomes available. These results were obtained in
collaboration with Gordon Kane at the University of Michigan.


title:
The ECLAIRs micro-satellite for multi-wavelength studies of gamma-ray
  burst prompt emission

abstract:
  The cosmological revolution of 1997 has established that (at least long
duration) gamma-ray bursts (GRB) are among the most energetic events in the
Universe and occur at cosmological distances. The ECLAIRs micro-satellite, to
be launched in 2009, will provide multi-wavelength observations for
astrophysical studies of GRB and for their possible use as cosmological probes.
It is expected to be the only space borne GRB trigger available for ground
based robotic telescopes operational at that time. This paper presents the
ECLAIRs project and its status. An X/gamma-ray camera onboard ECLAIRs with a
wide field of view of 2 sr, will detect ~100 GRB/yr in the 4-50 keV energy
range, localize the GRB with a precision of ~10 arcmin on the sky, and transmit
this information to the ground in near real-time, as a GRB trigger for ground
based optical telescopes. Inspired by the INTEGRAL imager IBIS, it is based on
a CdTe detection plane covering 1000 cm^2, placed 35 cm below a coded mask. An
optical camera, sensitive to magnitude-15 stars, covering up to 1/4th of the
X/gamma-ray camera's field of view, will observe the prompt emission and a
possible precursor of ~10 GRB/yr in the visible-band. Used in a continuous
acquisition mode at a rate of ~5 images/s dumped into an on-board memory, a GRB
event sent by the X/gamma-ray camera triggers a seek-back in memory for the GRB
optical precursor. The full X/gamma-ray and visible-band data of a GRB are sent
to ground when a high data-rate telemetry ground receiver is reachable.


title: The ISGRI CdTe gamma camera In-flight behavior

abstract:
  The INTEGRAL Soft Gamma-Ray Imager (ISGRI) is the first large CdTe gamma
camera ever built. It provided faultless operations in space since the launch
of INTEGRAL in October 2002. A general presentation of the system is given with
particular attention to the noisy pixel handling. The observed effect of charge
particles on the detectors and their integrated electronics is presented. The
in-flight detector evolution is detailed and the camera performance is
reviewed.


title: The Planck Low Frequency Instrument

abstract:
  Planck is the third generation of mm-wave instruments designed for space
observations of the cosmic microwave background (CMB) anisotropies within the
new Cosmic Vision 2020 ESA Science Program. Planck will map the whole sky with
unprecedented sensitivity, angular resolution, and frequency coverage, and it
likely leads us to the final comprehension of the CMB anisotropies. The Low
Frequency Instrument (LFI), operating in the 30-70 GHz range, is one of the two
instruments onboard Planck satellite, sharing the focal region of a 1.5 meter
off-axis dual reflector telescope together with the High Frequency Instrument
(HFI) operating at 100-857 GHz. We present LFI and discuss the major
instrumental systematic effects that could degrade the measurements and the
solutions adopted in the design and data analysis phase in order to adequately
reduce and control them.


title: Evidence for radio-source heating of groups

abstract:
  We report evidence that the gas properties of X-ray groups containing radio
galaxies differ from those of radio-quiet groups. For a well-studied sample of
ROSAT-observed groups, we found that more than half of the elliptical-dominated
groups can be considered ``radio-loud'', and that radio-loud groups are likely
to be hotter at a given X-ray luminosity than radio-quiet groups. We tested
three different models for the origin of the effect and conclude that
radio-source heating is the most likely explanation. We found several examples
of groups where there is strong evidence from Chandra or XMM-Newton images for
interactions between the radio source and the group gas. A variety of
radio-source heating processes are important, including shock-heating by young
sources and gentler heating by larger sources. The heating effects can be
longer-lasting than the radio emission. We show that the sample of X-ray groups
used in our study is not significantly biased in the fraction of radio-loud
groups that it contains. This allows us to conclude that the energy per
particle that low-power radio galaxies can inject over the group lifetime is
comparable to the requirements of structure formation models.


title:
SPI observations of positron annihilation radiation from the 4th
  galactic quadrant: Spectroscopy

abstract:
  The status of the analysis of the electron/positron annihilation radiation
performed by INTEGRAL/SPI in the 4th GALACTIC QUADRANT is reported. We use data
from the first two Galactic Center Deep Exposures (GCDE) and from the Galactic
Plane Scans (GPS). The analysis presented here is focused on the spectroscopic
aspects of the electron/positron annihilation radiation. Background
substraction and model fitting methods are described, and the parameters of the
511 keV line (flux, energy, and width) are deduced.


title:
Cosmological reionization after WMAP: perspectives from PLANCK and
  future CMB missions

abstract:
  The WMAP first year detection of a high redshift reionization through its
imprints on CMB anisotropy T and TE mode angular power spectra calls for a
better comprehension of the universe ionization and thermal history after the
standard recombination. Different reionization mechanisms predict different
signatures in the CMB, both in temperature and polarization anisotropies and in
spectral distortions. The Planck capability to distinguish among different
scenarios through its sensitivity to T, TE, and E mode angular power spectra is
discussed. Perspectives open by future high sensitivity experiments on the CMB
polarization anisotropy and spectrum are also presented.


title: Mid-infrared selection of quasar-2s in Spitzer's First Look Survey

abstract:
  We present early results from the spectroscopic follow-up of a sample of
candidate obscured AGN selected in the mid-infrared from the Spitzer First Look
Survey. Our selection allows a direct comparison of the numbers of obscured and
unobscured AGN at a given luminosity for the first time, and shows that the
ratio of obscured to unobscured AGN at infrared luminosities corresponding to
low luminosity quasars is ~1:1 at z~0.5. Most of our optically-faint candidate
obscured AGN have the high-ionization, narrow-line spectra expected from type-2
AGN. A composite spectrum shows evidence for Balmer absorption lines,
indicating recent star-formation activity in the host galaxies. There is
tentative evidence for a decrease in the obscured AGN fraction with increasing
AGN luminosity.


title: A supermassive binary black hole in the quasar 3C345

abstract:
  Radio loud active galactic nuclei present a remarkable variety of signs
indicating the presence of periodical processes possibly originating in binary
systems of supermassive black holes, in which orbital motion and precession are
ultimately responsible for the observed broad-band emission variations, as well
as for the morphological and kinematic properties of the radio emission on
parsec scales. This scenario, applied to the quasar 3C345, explains the
observed variations of radio and optical emission from the quasar, and
reproduces the structural variations observed in the parsec-scale jet of this
object. The binary system in 3C345 is described by two equal-mass black holes
with masses of approximately 7*10^8 solar masses separated by ~0.33 pc and
orbiting with a period of ~480 yr. The orbital motion induces a precession of
the accretion disk around the primary black hole, with a period of ~2570 yr.
The jet plasma is described by a magnetized, relativistic electron-positron
beam propagating inside a wider and slower electron-proton jet. The combination
of Alfven wave perturbations of the beam, the orbital motion of the binary
system and the precession of the accretion disk reproduces the variability of
the optical flux and evolution of the radio structure in 3C345. The timescale
of quasi-periodic flaring activity in 3C345 is consistent with typical disk
instability timescales. The present model cannot rule out a small-mass orbiter
crossing the accretion disk and causing quasi-periodic flares.


title: Contamination and exclusion in the sigma Orionis young group

abstract:
  We present radial velocities for 38 low-mass candidate members of the sigma
Orionis young group. We have measured their radial velocities by
cross-correlation of high resolution (R~6000) AF2/WYFFOS spectra of the gravity
sensitive NaI doublet at 8183, 8195Angstroms. The total sample contained 117
objects of which 54 have sufficient signal-to-noise to detect NaI at an
equivalent width of 3Angstroms, however we only detect NaI in 38 of these. This
implies that very low-mass members of this young group display weaker NaI
absorption than similarly aged objects in the Upper Scorpius OB association. We
develop a technique to assess membership using radial velocities with a range
of uncertainties that does not bias the selection when large uncertainties are
present. The resulting membership probabilities are used to assess the issue of
exclusion in photometric selections, and we find that very few members are
likely to be excluded by such techniques.
  We also assess the level of contamination in the expected pre-main sequence
region of colour-magnitude space brighter than I = 17. We find that
contamination by non-members in the expected PMS region of the colour-magnitude
diagram is small. We conclude that although radial velocity alone is
insufficient to confirm membership, high signal-to-noise observations of the
NaI doublet provide the opportunity to use the strength of NaI absorption in
concert with radial velocities to asses membership down to the lowest masses,
where Lithium absorption no longer distinguishes youth.


title:
A minimum hypothesis explanation for an IMF with a lognormal body and
  power law tail

abstract:
  We present a minimum hypothesis model for an IMF that resembles a lognormal
distribution at low masses but has a distinct power-law tail. Even if the
central limit theorem ensures a lognormal distribution of condensation masses
at birth, a power-law tail in the distribution arises due to accretion from the
ambient cloud, coupled with a non-uniform (exponential) distribution of
accretion times.


title: Turbulence and Magnetic Fields in Clouds

abstract:
  We discuss several categories of models which may explain the IMF, including
the possible role of turbulence and magnetic fields.


title:
Longitudinal development of extensive air showers: hybrid code SENECA
  and full Monte Carlo

abstract:
  New experiments, exploring the ultra-high energy tail of the cosmic ray
spectrum with unprecedented detail, are exerting a severe pressure on extensive
air hower modeling. Detailed fast codes are in need in order to extract and
understand the richness of information now available. Some hybrid simulation
codes have been proposed recently to this effect (e.g., the combination of the
traditional Monte Carlo scheme and system of cascade equations or pre-simulated
air showers). In this context, we explore the potential of SENECA, an efficient
hybrid tridimensional simulation code, as a valid practical alternative to full
Monte Carlo simulations of extensive air showers generated by ultra-high energy
cosmic rays. We extensively compare hybrid method with the traditional, but
time consuming, full Monte Carlo code CORSIKA which is the de facto standard in
the field. The hybrid scheme of the SENECA code is based on the simulation of
each particle with the traditional Monte Carlo method at two steps of the
shower development: the first step predicts the large fluctuations in the very
first particle interactions at high energies while the second step provides a
well detailed lateral distribution simulation of the final stages of the air
shower. Both Monte Carlo simulation steps are connected by a cascade equation
system which reproduces correctly the hadronic and electromagnetic longitudinal
profile. We study the influence of this approach on the main longitudinal
characteristics of proton-induced air showers and compare the predictions of
the well known CORSIKA code using the QGSJET hadronic interaction model.


title: A Resolved Debris Disk around the G2V star HD 107146

abstract:
  We present resolved scattered-light images of the debris disk around HD
107146, a G2 star 28.5 pc from the Sun. This is the first debris disk to be
resolved in scattered light around a solar-type star. We observed it with the
HST/ACS coronagraph, using a 1.8'' occulting spot and the F606W (broad V) and
F814W (broad I) filters. Within 2'' from the star, the image is dominated by
PSF subtraction residuals. Outside this limit, the disk looks featureless
except for a northeast-southwest brightness asymmetry that we attribute to
forward scattering. The disk has scattered-light fractional luminosities of
$(L_{Sca}/L_*)_{F606W}=6.8 \pm 0.8 \times 10^{-5}$ and
$(L_{Sca}/L_*)_{F814W}=10 \pm 1 \times 10^{-5}$ and it is detected up to 6.5''
away from the star. To map the surface density of the disk, we deproject it by
$25^\circ \pm 5^\circ$, divide by the dust scattering phase ($g_{F606W} = 0.3
\pm 0.1$, $g_{F814W} = 0.2 \pm 0.1$) and correct for the geometric dilution of
starlight. Within the errors, the surface density has the same shape in each
bandpass, and it appears to be a broad (85 AU) ring with most of the opacity
concentrated at 130 AU. The ratio of the relative luminosity in F814W to that
in F606W has the constant value of $1.3\pm0.3$, with the error dominated by
uncertainties in the value of $g$ in each filter. An examination of far
infrared and submillimeter measurements suggests the presence of small grains.
The colors and the derived values of $g$ are consistent with the presence of
dust particles smaller than the radiation pressure limit. The dust generated by
the creation of a small planet or the scattering and circularization of a large
one, are possible scenarios that may explain the shape of the surface density
profile.


title:
Understanding Compact Object Formation and Natal Kicks I. Calculation
  Methods and the case of GRO J1655-40

abstract:
  In recent years proper motion measurements have been added to the set of
observational constraints on the current properties of Galactic X-ray binaries.
We develop an analysis that allows us to consider all this available
information and reconstruct the full evolutionary history of X-ray binaries
back to the time of compact object formation. This analysis accounts for mass
transfer through the ongoing X-ray phase, tidal circularization before the
onset of Roche-lobe overflow, motion through the Galactic potential after the
formation of the compact object, and binary orbital dynamics and hydrodynamic
modeling of the core collapse. We apply the analysis to the soft X-ray
transient GRO J1655-40 and, for the first time, use its full 3D peculiar
velocity constraints right after core collapse instead of lower limits on the
current space velocity given by the present-day radial velocity. We find that
the system has remained within 200pc from the Galactic plane throughout its
entire life time and that the mass loss and a kick possibly associated with the
black hole (BH) formation imparted a kick velocity of 45-115 km/s to the
binary's center of mass. Right after BH formation, the system consists of a
3.5-6.3 Msun BH and a 2.3-4 Msun main-sequence star. At the onset of the X-ray
phase the donor is still on the main sequence. We find that a symmetric BH
formation event cannot be formally excluded, but that the associated system
parameters are only marginally consistent with the currently observed binary
properties. BH formation mechanisms involving an asymmetric supernova explosion
with associated BH kick velocities of a few tens of km/s, on the other hand,
satisfy the constraints much more comfortably. We also derive an upper limit on
the BH kick magnitude of 210 km/s. (abridged)


title:
The GALEX-VVDS Measurement of the Evolution of the Far-Ultraviolet
  Luminosity Density and the Cosmic Star Formation Rate

abstract:
  In a companion paper (Arnouts et al. 2004) we presented new measurements of
the galaxy luminosity function at 1500 Angstroms out to z~1 using GALEX-VVDS
observations (1039 galaxies with NUV<24.5 and z>0.2) and at higher z using
existing data sets. In this paper we use the same sample to study evolution of
the FUV luminosity density. We detect evolution consistent with a
(1+z)^{2.5+/-0.7} rise to z~1 and (1+z)^{0.5+/-0.4} for z>1. The luminosity
density from the most UV-luminous galaxies (UVLG) is undergoing dramatic
evolution (x30) between 0<z<1. UVLGs are responsible for a significant fraction
(>25%) of the total FUV luminosity density at z<1. We measure dust attenuation
and star formation rates of our sample galaxies and determine the star
formation rate density as a function of redshift, both uncorrected and
corrected for dust. We find good agreement with other measures of the SFR
density in the rest ultraviolet and Halpha given the still significant
uncertainties in the attenuation correction.


title:
Are Supernova Kicks Responsible for X-ray Binary Ejection from Young
  Clusters?

abstract:
  Recent Chandra observations of interacting and starburst galaxies have led us
to investigate the apparent correlation between the positions of young star
clusters and Chandra point sources. Assumed to be X-ray binaries (XRBs), these
point sources do not seem to coincide with the massive (~1e5 Msun), young (1-50
Myr) stellar clusters that can easily form systems capable of such emission. We
use a sophisticated binary evolution and population synthesis code (StarTrack)
and a simplified cluster model to track both the X-ray luminosity and position
of XRBs as a function of time. These binaries are born within the cluster
potential with self-consistent positions and velocities and we show that a
large fraction (~70%) can be ejected from the parent due to supernova
explosions and associated systemic velocities. For brighter sources and cluster
masses below ~1e6 Msun, we find that the average number of bright XRBs per
cluster remains near or below unity, consistent with current observations.


title: Quantifying Substructure Using Galaxy-Galaxy Lensing in Distant Clusters

abstract:
  We present high-resolution mass reconstructions for five massive
cluster-lenses spanning a redshift range from z = 0.18 - 0.57 utilizing
archival Hubble Space Telescope data and applying galaxy-galaxy lensing
techniques. These detailed mass models were obtained by combining constraints
from the observed strong and weak lensing regimes. Quantifying the local weak
distortions in the shear maps in terms of perturbations induced by the presence
of galaxy halos around individual bright early-type cluster member galaxies, we
estimate the fraction of mass in the central regions of these clusters that can
be associated with small scale mass clumps. This technique enables us to
directly map the substructure in the mass range 10^{11} - 10^{12.5} solar
masses which we associate with galaxy-scale sub-halos. The determination of the
mass spectrum of substructure in the inner regions of these clusters is
presented. Constraints are thereby obtained on the masses, mass-to-light ratios
and truncation radii for these sub-halos. We find that the fraction of total
cluster mass associated with individual sub-halos within the inner 0.5h^{-1} -
0.8h^{-1} Mpc of these clusters ranges from 10 - 20%. Our results have
important implications for the survival and evolution of substructure in high
density cluster cores and are consistent with the theoretical picture of tidal
stripping of galaxy-scale halos in high-density cluster environments as
expected in hierarchical Cold Dark Matter dominated structure formation
scenarios.


title: Does solar structure vary with solar magnetic activity?

abstract:
  We present evidence that solar structure changes with changes in solar
activity. We find that the adiabatic index, Gamma_1, changes near the second
helium ionization, i.e., at a depth of about 0.98 R_sun. We believe that this
change is a result of the change in the effective equation of state caused by
magnetic fields. Inversions should be able to detect the changes in Gamma_1 if
mode sets with reliable and precise high-degree modes are available.


title: FUSE Observations of Nebular O VI Emission from NGC 6543

abstract:
  NGC 6543 is one of the few planetary nebulae (PNe) whose X-ray emission has
been shown to be extended and originate from hot interior gas. Using FUSE
observations we have now detected nebular O VI emission from NGC 6543. Its
central star, with an effective temperature of ~50,000 K, is too cool to
photoionize O V, so the O VI ions must have been produced by thermal collisions
at the interface between the hot interior gas and the cool nebular shell. We
modeled the O VI emission incorporating thermal conduction, but find that
simplistic assumptions for the AGB and fast wind mass loss rates overproduce
X-ray emission and O VI emission. We have therefore adopted the pressure of the
interior hot gas for the interface layer and find that expected O VI emission
to be comparable to the observations.


title:
EGRET upper limits and stacking searches of gamma-ray observations of
  luminous and ultra-luminous infrared galaxies

abstract:
  We present a stacking analysis of EGRET $\gamma$-ray observations at the
positions of luminous and ultraluminous infrared galaxies. The latter were
selected from the recently presented HCN survey, which is thought to contain
the most active star forming regions of the universe. Different sorting
criteria are used and, whereas no positive collective detection of $\gamma$-ray
emission from these objects we determined both collective and individual upper
limits. The upper most excess we find appears in the case of ULIRGs ordered by
redshift, at a value of 1.8$\sigma$.


title:
Large-Scale Non-Gaussianities in the 21 cm Background Anisotropies From
  the Era of Reionization

abstract:
  The brightness temperature fluctuations in the 21 cm background related to
neutral Hydrogen distribution provide a probe of physics related to the era of
reionization when the intergalactic medium changed from a completely neutral to
a partially ionized one. We formulate statistics of 21 cm brightness
temperature anisotropies in terms of the angular power spectrum, the
bispectrum, and the trispectrum. Using the trispectrum, we estimate the
covariance related to the power spectrum measurements and show that
correlations resulting from non-Gaussianities are below a percent, at most.
While all-sky observations of the 21 cm background at arcminute-scale
resolution can be used to measure the bispectrum with a cumulative
signal-to-noise ratio of order a few ten, in the presence of foregrounds and
instrumental noise related to first-generation interferometers, the measurement
is unlikely to be feasible. For most purposes, non-Gaussianities in 21 cm
fluctuations can be ignored and the distribution can be described with Gaussian
statistics. Since 21 cm fluctuations are significantly contaminated by
foregrounds, such as galactic synchrotron or low-frequency radio point sources,
the lack of a significant non-Gaussianity in the signal suggests that any
significant detection of a non-Gaussianity can be due to foregrounds.
Similarly, in addition to frequency information that is now proposed to
separate 21 cm fluctuations from foregrounds, if the non-Gaussian structure of
foregrounds is a priori known, one can potentially use this additional
information to further reduce the confusion.


title: Far-IR Detection Limits I: Sky Confusion Due to Galactic Cirrus

abstract:
  Fluctuations in the brightness of the background radiation can lead to
confusion with real point sources. Such background emission confusion will be
important for infrared observations with relatively large beam sizes since the
amount of fluctuation tends to increase with angular scale. In order to
quantitively assess the effect of the background emission on the detection of
point sources for current and future far-infrared observations by space-borne
missions such as Spitzer, ASTRO-F, Herschel and SPICA, we have extended the
Galactic emission map to higher angular resolution than the currently available
data. Using this high resolution map, we estimate the sky confusion noise due
to the emission from interstellar dust clouds or cirrus, based on fluctuation
analysis and detailed photometry over realistically simulated images. We find
that the confusion noise derived by simple fluctuation analysis agrees well
with the result from realistic simulations. Although the sky confusion noise
becomes dominant in long wavelength bands (> 100 um) with 60 - 90cm aperture
missions, it is expected to be two order of magnitude smaller for the next
generation space missions with larger aperture sizes such as Herschel and
SPICA.