title:
A Joint Mid-Infrared Spectroscopic and X-Ray Imaging Investigation of
  Liner Galaxies

abstract:
  We present a comprehensive comparative high resolution mid-IR spectroscopic
and X-ray imaging investigation of LINERs using archival observations from the
ISO-SWS and the Chandra Advanced CCD Imaging Spectrometer. Although the sample
is heterogenous and incomplete, this is the first comprehensive study of the
mid-infrared fine structure line emission of LINERs. These results have been
compared with similar observations of starburst galaxies and AGN. We find that
LINERs very clearly fall between starbursts and AGN in their mid-IR fine
structure line spectra, showing L_[OIV]26um/L_FIR and
L_[OIV]26um/L_[NeII]12.8um ratios, both measures of the dominant nuclear energy
source in dust-enshrouded galaxies, intermediate between those of AGN and
starbursts. Chandra imaging observations of the LINERs reveal hard nuclear
point sources morphologically consistent with AGN in most (67%) of the sample,
with a clear trend with IR-brightness. Most LINERs that show a single dominant
hard compact X-ray core are IR-faint ((L_FIR/L_B < 1), whereas most LINERs that
show scattered X-ray sources are IR-bright. A comparative X-ray/mid-IR
spectroscopic investigation of LINERs reveals some puzzling results. Objects
that display strong hard nuclear X-ray cores should also display high
excitation lines in the IR. However, we find two LINERs disagree with this
expectation. The galaxy NGC 404 shows weak soft X-ray emission consistent with
a starburst but has the most prominent highest excitation mid-IR spectrum of
our entire sample. Using IR emission line diagnostics alone, this galaxy would
be classified as hosting a dominant AGN. Conversely, the IR luminous LINER NGC
6240 has an extremely luminous binary AGN as revealed by the X-rays but shows
weak IR emission lines.


title:
Compact Nuclear Starbursts in Seyfert 2 Galaxies from the CfA and 12
  Micron Samples

abstract:
  We present infrared 2.8-4.1 micron slit spectra of 32 Seyfert 2 galaxies in
the CfA and 12 micron samples. The 3.3 micron polycyclic aromatic hydrocarbon
(PAH) emission feature was used to estimate the absolute magnitude of a compact
nuclear starburst (< a few 100 pc in size) that is presumed to have occurred in
the outer region of an obscuring dusty molecular torus around a central
supermassive black hole. We detected 3.3 micron PAH emission in 11 of the 32
Seyfert 2 nuclei in our sample, providing evidence for the presence of compact
nuclear starbursts in a significant fraction of Seyfert 2 nuclei. However, the
rest-frame equivalent widths of the 3.3 micron PAH emission, and the 3.3 micron
PAH-to-infrared luminosity ratios measured in this study suggest that compact
nuclear starbursts generally do not contribute significantly to the observed
3-4 micron nuclear fluxes or to the infrared luminosities of Seyfert 2
galaxies. Small optical depths of absorption features at 3.4 micron from bare
dust and at 3.1 micron from ice-covered dust suggest that dust extinction
toward the 3-4 micron continuum-emitting region in the innermost part of the
obscuring dusty torus is modest: AV < 50-60 mag. Finally, the 3.3 micron PAH
emission luminosities measured in this study were found to be significantly
correlated with IRAS 12- and 25-micron, and nuclear N-band (10.6 micron)
luminosities. If these three luminosities trace the power of the active
galactic nucleus (AGN), then the luminosities of compact nuclear starbursts and
AGNs are correlated. This correlation is in agreement with theories predicting
that the presence of a compact nuclear starburst in the torus leads to an
enhancement of the mass accretion rate onto the central supermassive black
hole.


title:
Ejection of hypervelocity stars by the (binary) black hole(s) in the
  Galactic center

abstract:
  We study three processes that eject hypervelocity (>10^3 km/s) stars from the
Galactic center: (i) close encounters of two single stars; (ii) tidal breakup
of binary stars by the central black hole, as originally proposed by Hills; and
(iii) three-body interactions between a star and a binary black hole (BBH).
Mechanism (i) expels hypervelocity stars to the solar radius at a negligible
rate, ~10^{-11}/yr. Mechanism (ii) expels hypervelocity stars at a rate ~
10^{-5}(\eta/0.1)/yr, where \eta is the fraction of stars in binaries with
semimajor axis a_b<~0.3 AU. For solar-mass stars, the corresponding number of
hypervelocity stars within the solar radius R_0=8 kpc is ~60(\eta/0.1)(a_b/0.1
AU)^{1/2}. For mechanism (iii), Sgr A^* is assumed to be one component of a
BBH. We constrain the allowed parameter space (semimajor axis, mass ratio) of
the BBH. In the allowed region (for example, semimajor axis of 0.5x10^{-3} pc
and mass ratio of 0.01), the rate of ejecting hypervelocity stars can be as
large as ~10^{-4}/yr and the expected number of hypervelocity stars within the
solar radius can be as large as ~10^3. Hypervelocity stars may be detectable by
the next generation of large-scale optical surveys.


title: The deuterium-to-oxygen ratio in the interstellar medium

abstract:
  Because the ionization balances for HI, OI, and DI are locked together by
charge exchange, D/O is an important tracer for the value of the D/H ratio and
for potential spatial variations in the ratio. As the DI and OI column
densities are of similar orders of magnitude for a given sight line,
comparisons of the two values will generally be less subject to systematic
errors than comparisons of DI and HI, which differ by about five orders of
magnitude. Moreover, D/O is additionally sensitive to astration, because as
stars destroy deuterium, they should produce oxygen. We report here the results
of a survey of D/O in the interstellar medium performed with FUSE. We also
compare these results with those for D/N. Together with a few results from
previous missions, the sample totals 24 lines of sight. The distances range
from a few pc to ~2000 pc and log N(DI) from ~13 to ~16 (cm-2). The D/O ratio
is constant in the local interstellar medium out to distances of ~150 pc and
N(DI) ~ 1x10^15 cm-2, i.e. within the Local Bubble. In this region of the
interstellar space, we find D/O = (3.84+/-0.16)x10^-2 (1 sigma in the mean).
The homogeneity of the local D/O measurements shows that the spatial variations
in the local D/H and O/H must be extremely small, if any. A comparison of the
Local Bubble mean value with the few D/O measurements available for low
metallicity quasar sight lines shows that the D/O ratio decreases with cosmic
evolution, as expected. Beyond the Local Bubble we detected significant spatial
variations in the value of D/O. This likely implies a variation in D/H, as O/H
is known to not vary significantly over the distances covered in this study.
Our dataset suggests a present-epoch deuterium abundance below 1x10^-5, i.e.
lower than the value usually assumed, around 1.5x10^-5.


title: The Thermal Stability of Mass-Loaded Flows

abstract:
  We present a linear stability analysis of a flow undergoing
conductively-driven mass-loading from embedded clouds. We find that
mass-loading damps isobaric and isentropic perturbations, and in this regard is
similar to the effect of thermal conduction, but is much more pronounced where
many embedded clumps exist. The stabilizing influence of mass-loading is
wavelength independent against isobaric (condensing) perturbations, but
wavelength dependent against isentropic (wave-like) perturbations. We derive
equations for the degree of mass-loading needed to stabilize such
perturbations. We have also made 1D numerical simulations of a mass-loaded
radiative shock and demonstrated the damping of the overstability when
mass-loading is rapid enough.


title:
The Formation of Broad Emission Line Regions in Supernova-QSO Wind
  Interactions II. 2D Calculations

abstract:
  One aspect of supernova remnant evolution that is relatively unstudied is the
influence of an AGN environment. A high density ambient medium and a nearby
powerful continuum source will assist the cooling of shocked ejecta and
swept-up gas. Motion of the surrounding medium relative to the remnant will
also affect the remnant morphology. In an extension to previous work we have
performed 2D hydrodynamical calculations of SNR evolution in an AGN
environment, and have determined the evolutionary behaviour of cold gas in the
remnant. The cold gas will contribute to the observed broad line emission in
AGNs, and we present preliminary theoretical line profiles from our
calculations. A more detailed comparison with observations will be performed in
future work. The SNR-AGN interaction may be useful as a diagnostic of the AGN
wind.


title: The orbital period distribution of subdwarf B binaries

abstract:
  We present the results of a 3.5 year long campaign to measure orbital periods
of subdwarf B (sdB) star binaries. We directly compare our observed orbital
period distribution with that predicted by using binary population synthesis.
Up to now, most of our systems seem to have been formed through two of the
formation channels discussed by Han et al.(2003), i.e. the first and the second
common envelope ejection (CE) channels. At this point, thanks to the long
baseline of our observations, we are starting to detect also very long orbital
period systems. These have probably come from a complete different formation
path, the first stable Roche Lobe overflow (RLOF) channel in which the first
mass transfer phase is stable. This channel is expected to lead to the
formation of very wide binaries with orbital periods ranging between 0.5 to
2000 days.


title:
XMM-Newton observation of the Chandra Deep Field-South: Statistical
  treatment of faint source spectra

abstract:
  We present first results of the X-ray spectral analysis of the 500 ksec deep
survey obtained with XMM-Newton on the Chandra Deep Field South (CDFS).
Statistical distributions of spectral index and intrinsic absorption are
derived for a sample containing 70 sources with a count limit of 100 (flux
limit in the [2-10] keV band of 8.9 $\times 10^{-16}$ erg cm$^{-2}$ s$^{-1}$),
of which 44 have redshift identification. We observe a separation between the
type-1 and the type-2 AGN in diagnostics involving different X-ray parameters.
Using the subsample with known $z$, we show that this separation between the
AGN populations is a consequence of different absorption column densities. The
two populations have the same average spectral index, $<\Gamma> = 2 \pm 0.1$.
  We present integrated spectrum for the most distant type-2 QSO whith strong
X-ray absorption and a clear soft excess; we obtained the best fit for these
objects with two difference models: a scattering model and a double power law
model. We also confirm a progressive hardening for the combined integrated
spectra for faint objects which at first was noted by \cite{toz01a}. Our
results shown a clear evolution of decrease of $<\Gamma>$ with decreasing flux
in the hard 2-10 keV band. However, we detect not only a regular increase of
$<\Gamma>$ for different subsamples of fluxes in comparison with Chandra
results, but also an internal discrepancy of the values, if we fitted in the
different energy bands.


title: A Rocket Model of Neutrino Jet for Pulsar Kick

abstract:
  On the basis of the neutrino emission from the isotropic $^1$S$_0$ neutron
superfluid vortexes in neutron star interiors, we propose a rocket model of
neutrino jet for the observed pulsar kick.


title: Simultaneous multi-wavelength observations of GRS 1915+105

abstract:
  We present the result of multi-wavelength observations of the microquasar GRS
1915+105 in a plateau state with a luminosity of ~7.5x10^{38) erg s-1 (~40%
L_Edd), conducted simultaneously with the INTEGRAL and RXTE satellites, the
ESO/NTT, the Ryle Telescope, the NRAO VLA and VLBA, in 2003 April 2-3. For the
first time were observed concurrently in GRS 1915+105 all of the following
properties: a strong steady optically thick radio emission corresponding to a
powerful compact jet resolved with the VLBA, bright near-IR emission, a strong
QPO at 2.5 Hz in the X-rays and a power law dominated spectrum without any
cutoff in the 3-400 keV range.


title: Compton Sailing and Strong Polarization

abstract:
  It is noted that a surface layer of matter in contact with a sufficiently
super-Eddington, radially combed photon flux typically attains a relativistic
coasting state whereby the radiation does not accelerate the matter. Radiation
that scatters off this layer is most likely to be observed along the velocity
vector of the matter, where it would be most strongly polarized.


title:
Asteroseismology of HADS stars: V974 Oph, a radial pulsator flavoured by
  nonradial components

abstract:
  The analysis of a dense time-series on V974 Oph disclosed the rich
pulsational content (at least five independent terms) of this high-amplitude
(0.60 mag in B-light) Delta Sct star. A mode with a frequency very close to the
main one (probably the fundamental radial mode) has been detected: such a
doublet is not a common feature in stars of the same class. Also another term
can be considered a radial one, but the high ratio (0.786) raises some problems
that can be solved only by admitting very low metallicity. It is quite evident
that some undetectable terms are again hidden in the noise, as the
least--squares fit leaves a rms residual much higher than the observational
noise. All that considered, nonradial modes seem to play a key role in the
light variability of V974 Oph. Revealing an unsuspected asteroseismic interest,
V974 Oph provides a link between low- and high-amplitude Delta Sct stars. By
discussing other high-amplitude Delta Sct stars showing unusual period ratios,
it is evident that the asteroseismic approach is possible also for this class
of pulsators.


title: Ab initio simulations of accretion disks instability

abstract:
  We show that accretion disks, both in the subcritical and supercritical
accretion rate regime, may exhibit significant amplitude luminosity
oscillations. The luminosity time behavior has been obtained by performing a
set of time-dependent 2D SPH simulations of accretion disks with different
values of alpha and accretion rate. In this study, to avoid any influence of
the initial disk configuration, we produced the disks injecting matter from an
outer edge far from the central object. The period of oscillations is 2 - 50 s
respectively for the two cases, and the variation amplitude of the disc
luminosity is 10^38 - 10^39 erg/s. An explanation of this luminosity behavior
is proposed in terms of limit cycle instability: the disk oscillates between a
radiation pressure dominated configuration (with a high luminosity value) and a
gas pressure dominated one (with a low luminosity value). The origin of this
instability is the difference between the heat produced by viscosity and the
energy emitted as radiation from the disk surface (the well-known thermal
instability mechanism). We support this hypothesis showing that the limit cycle
behavior produces a sequence of collapsing and refilling states of the
innermost disk region.


title: Bubbles in Planetary Nebulae and Clusters of Galaxies: Jet Properties

abstract:
  I derive constraints on jet properties for inflating pairs of bubbles in
planetary nebulae and clusters of galaxies. This work is motivated by the
similarity in morphology and some non-dimensional quantities between
X-ray-deficient bubbles in clusters of galaxies and the optical-deficient
bubbles in planetary nebulae, which was pointed out in an earlier work. In the
present paper I find that for inflating fat bubbles, the opening angle of the
jets must be large, i.e., the half opening angle measured from the symemtry
axis of the jets should typically be larger than 40 degrees. Narrow jets will
form elongated lobes rather than fat bubbles. I emphasize the need to include
jets with large opening angle in simulating bubble inflation in both planetary
nebulae and (cooling flow) clusters of galaxies.


title:
The Ionized Gas and Nuclear Environment in NGC 3783. IV. Variability and
  Modeling of the 900 ks CHANDRA Spectrum

abstract:
  We present a detailed spectral analysis of the data obtained from NGC 3783
during the period 2000-2001 using Chandra. This analysis leads us to the
following results. 1) NGC 3783 fluctuated in luminosity by a factor ~1.5 during
individual observations (~170 ks duration). These fluctuations were not
associated with significant spectral variations. 2) On a longer time scale
(20-120 days), we found the source to exhibit two very different spectral
shapes. The main difference between these can be well-described by the
appearance and disappearance of a spectral component that dominates the
underlying continuum at the longest wavelengths. The spectral variations are
not related to the brightening or the fading of the continuum at short
wavelengths in any simple way. 3) The appearance of the soft continuum
component is consistent with being the only spectral variation, and there is no
need to invoke changes in the opacity of the absorbers. 4) Photoionization
modeling indicates that a combination of three ionized absorbers, each split
into two kinematic components, can explain the strengths of almost all the
absorption lines and bound-free edges. All three components are thermally
stable and seem to have the same gas pressure. 5) The only real discrepancy
between our model and the observations concerns the range of wavelengths
absorbed by the iron M-shell UTA feature. This most likely arises as the result
of our underestimation of the poorly-known dielectronic recombination rates
appropriate for these ions. 6) The lower limit on the distance of the absorbing
gas in NGC 3783 is between 0.2 and 3.2 pc. The assumption of pressure
equilibrium imposes an upper limit of about 25 pc on the distance of the
least-ionized component from the central source. (abridged)


title: SPI Measurements of Galactic 26Al

abstract:
  The precision measurement of the 1809 keV gamma-ray line from Galactic
$^{26}$Al is one of the goals of the SPI spectrometer on INTEGRAL with its Ge
detector camera. We aim for determination of the detailed shape of this
gamma-ray line, and its variation for different source regions along the plane
of the Galaxy. Data from the first part of the core program observations of the
first mission year have been inspected. A clear detection of the \Al line at
about 5--7 $\sigma$ significance demonstrates that SPI will deepen \Al studies.
The line intensity is consistent with expectations from previous experiments,
and the line appears narrower than the 5.4 keV FWHM reported by GRIS, more
consistent with RHESSI's recent value. Only preliminary statements can be made
at this time, however, due to the multi-component background underlying the
signal at \about 40 times higher intensity than the signal from Galactic
$^{26}$Al.


title:
Quantitative Description of the Sunyaev-Zeldovich Effect: Analytic
  Approximations

abstract:
  Various aspects of relativistic calculations of the Sunyaev-Zeldovich effect
are explored and clarified. We first formally show that the main previous
approaches to the calculation of the relativistically generalized thermal
component of the effect are equivalent. Our detailed description of the full
effect results in a somewhat improved formulation. Analytic approximations to
the exact calculation of the change of the photon occupation number in the
scattering, $\Delta n$, are extended to powers of the gas temperature and
cluster velocity that are higher than in similar published treatments. For the
purely thermal and purely kinematic components, we obtain identical terms up to
the highest common orders in temperature and cluster velocity, and to second
order in the Thomson optical depth, as reported in previous treatments, but we
get slightly different expressions for the terms that depend on both the gas
temperature and cluster velocity. We also obtain an accurate expression for the
crossover frequency.


title: Atomic Deuterium/Hydrogen in the Galaxy

abstract:
  An accurate value of the deuterium/hydrogen (D/H) ratio in the local
interstellar medium (LISM) and a better understanding of the D/H variations
with position in the Galactic disk can provide essential information on the
primordial D/H ratio in the Galaxy at the time of the protosolar nebula, and
the amount of astration and mixing in the Galaxy over time. Recent measurements
have been obtained with UV spectrographs on FUSE, HST, and IMAPS using hot
white dwarfs, OB stars, and late-type stars as background light sources against
which to measure absorption by D and H in the interstellar medium along the
lines of sight. Recent analyses of FUSE observations of seven white dwarfs and
subdwarfs provide a weighted mean value of D/H = (1.52 +/- 0.08) 10(-5) (15.2
+/- 0.8 ppm), consistent with the value of (1.50 +/- 0.10) 10(-5) (15.0 +/- 1.0
ppm) obtained from analysis of lines of sight toward nearby late-type stars.
Both numbers refer to the ISM within about 100 pc of the Sun, which samples
warm clouds located within the Local Bubble. Outside of the Local Bubble at
distances of 200 to 500 pc, analyses of far-UV spectra obtained with IMAPS
indicate a much wider range of D/H ratios between 0.8 to 2.2 ppm, providing
information on inhomogeneous astration in the Galactic disk.


title: Superhumps in Cataclysmic Binaries. XXIV. Twenty More Dwarf Novae

abstract:
  We report precise measures of the orbital and superhump period in twenty more
dwarf novae. For ten stars, we report new and confirmed spectroscopic periods -
signifying the orbital period P_o - as well as the superhump period P_sh. These
are GX Cas, HO Del, HS Vir, BC UMa, RZ Leo, KV Dra, KS UMa, TU Crt, QW Ser, and
RZ Sge. For the remaining ten, we report a medley of P_o and P_sh measurements
from photometry; most are new, with some confirmations of previous values.
These are KV And, LL And, WX Cet, MM Hya, AO Oct, V2051 Oph, NY Ser, KK Tel, HV
Vir, and RX J1155.4-5641.
  Periods, as usual, can be measured to high accuracy, and these are of special
interest since they carry dynamical information about the binary. We still have
not quite learned how to read the music, but a few things are clear. The
fractional superhump excess epsilon [=(P_sh-P_o)/P_o] varies smoothly with P_o.
The scatter of the points about that smooth curve is quite low, and can be used
to limit the intrinsic scatter in M_1, the white dwarf mass, and the
mass-radius relation of the secondary. The dispersion in M_1 does not exceed
24%, and the secondary-star radii scatter by no more than 11% from a fixed
mass-radius relation. For the well-behaved part of epsilon(P_o) space, we
estimate from superhump theory that the secondaries are 18+-6% larger than
theoretical ZAMS stars. This affects some other testable predictions about the
secondaries: at a fixed P_o, it suggests that the secondaries are (compared
with ZAMS predictions) 40+-14% less massive, 12+-4% smaller, 19+-6% cooler, and
less luminous by a factor 2.5(7). The presence of a well-defined mass-radius
relation, reflected in a well-defined epsilon(P_o) relation, strongly limits
effects of nuclear evolution in the secondaries.


title: High-Energy sources before INTEGRAL -- INTEGRAL reference catalog --

abstract:
  We describe the INTEGRAL reference catalog which classifies previously known
bright X-ray and gamma-ray sources before the launch of INTEGRAL. These sources
are, or have been at least once, brighter than ~1 mCrab above 3 keV, and are
expected to be detected by INTEGRAL. This catalog is being used in the INTEGRAL
Quick Look Analysis to discover new sources or significantly variable sources.
We compiled several published X-ray and gamma-ray catalogs, and surveyed recent
publications for new sources. Consequently, there are 1122 sources in our
INTEGRAL reference catalog. In addition to the source positions, we show an
approximate spectral model and expected flux for each source, based on which we
derive expected INTEGRAL counting rates. Assuming the default instrument
performances and at least ~10^5 sec exposure time for any part of the sky, we
expect that INTEGRAL will detect at least ~700 sources below 10 keV and ~400
sources above 20 keV over the mission life.


title: The diffuse X-ray background

abstract:
  The deepest observations of the X-ray background approach the surface
brightness of the truly diffuse component generated by Thomson scattering of
cosmic X-ray photons. Available estimates of the electron density and the X-ray
luminosity density of AGNs as a function of cosmological epoch are used to
calculate the integral scattered X-ray background component. It is shown that
the scattered component constitutes 1.0 - 1.7 % of the total background,
depending on the AGN cosmic evolution. Albeit this is a minute fragment of the
total flux, it becomes a perceptible fraction of the still unresolved part of
the background and should be taken into account in the future rigorous
assessments of the X-ray background structure. This diffuse component at
energies < 1 keV sums up with the emission by WHIM to 3 - 4 %. Consequently,
one should expect that integrated counts of discrete sources account for just
96 - 97 % for soft background and ~99 % at higher energies.


title:
The Mass Ratio Distribution in Main-Sequence Spectroscopic Binaries
  Measured by IR Spectroscopy

abstract:
  We report infrared spectroscopic observations of a large, well-defined sample
of main-sequence, single-lined spectroscopic binaries in order to detect the
secondaries and derive the mass ratio distribution of short-period binaries.
The sample consists of 51 Galactic disk spectroscopic binaries found in the
Carney and Latham high-proper-motion survey, with primary masses in the range
of 0.6--0.85 msun. Our infrared observations detect the secondaries in 32
systems, two of which have mass ratios, q=M_2/M_1, as low as ~0.20. Together
with 11 systems previously identified as double-lined binaries by visible light
spectroscopy, we have a complete sample of 62 binaries, out of which 43 are
double-lined. The mass ratio distribution is approximately constant over the
range q=1.0 to 0.3. The distribution appears to rise at lower q values, but the
uncertainties are sufficiently large that we cannot rule out a distribution
that remains constant. The mass distribution derived for the secondaries in our
sample, and that of the extra-solar planets, apparently represent two distinct
populations.


title:
The effect of the process of star formation on the temporal evolution of
  the WR and O-type star populations in the Solar Neighbourhood

abstract:
  A comparison between the observed O-type star and the WR star populations and
the theoretically predicted ones depends on the effects of stellar wind mass
loss during various phases and rotation on stellar evolution and, last not
least, on the effects of binaries. Obviously, both populations depend on the
massive star formation rate. In the present paper we show that the rate in the
Solar Neighbourhood is fluctuating on a timescale which is smaller than the
evolutionary timescale of a massive star. We demonstrate that this fluctuating
behaviour affects both population enormously, in such a way that a comparison
between observations and theoretical prediction to test stellar evolutionary
models is ambiguous.


title:
The Great Observatories Origins Deep Survey: Initial Results From
  Optical and Near-Infrared Imaging

abstract:
  This Special Issue of the Astrophysical Journal Letters is dedicated to
presenting initial results from the Great Observatories Origins Deep Survey
(GOODS) that are primarily, but not exclusively, based on multi--band imaging
data obtained with the {\it Hubble Space Telescope} ({\it HST}) and the
Advanced Camera for Surveys (ACS). The survey covers roughly 320 square
arcminutes in the ACS F435W, F606W, F814W, and F850LP bands, divided into two
well-studied fields. Existing deep observations from the {\it Chandra} X-ray
Observatory (\cxo) and ground-based facilities are supplemented with new, deep
imaging in the optical and near-infrared from the European Southern Observatory
(ESO) and from the Kitt Peak National Observatory (KPNO). Deep observations
with the {\it Space Infrared Telescope Facility} (SIRTF) are scheduled. Reduced
data from all facilities are being released worldwide within three to six
months of acquisition. Together, this data set provides two deep reference
fields for studies of distant normal and active galaxies, supernovae, and faint
stars in our own galaxy. This paper serves to outline the survey strategy and
describe the specific data that have been used in the accompanying letters,
summarizing the reduction procedures and sensitivity limits.


title: A cross-correlation of WMAP and ROSAT

abstract:
  We cross-correlate the recent CMB WMAP 1 year data with the diffuse soft
X-ray background map of ROSAT. We look for common signatures due to galaxy
clusters (SZ effect in CMB, bremsstrahlung in X-rays) by cross-correlating the
two maps in real and in Fourier space. We do not find any significant
correlation and we explore the different reasons for this lack of correlation.
The most likely candidates are the possibility that we live in a low $\sigma
_8$ universe ($\sigma_8 < 0.9$) and/or systematic effects in the data
especially in the diffuse X-ray maps which may suffer from significant cluster
signal subtraction during the point source removal process.


title:
Cyclotron-Synchrotron: harmonic fitting functions in the
  non-relativistic and trans-relativistic regimes

abstract:
  The present work investigates the calculation of absorption and emission
cyclotron line profiles in the non-relativistic and trans-relativistic regimes.
We provide fits for the ten first harmonics with synthetic functions down to
10^(-4) of the maximum flux with an accuracy of 20 per cent at worst. The lines
at a given particle energy are calculated from the integration of the Schott
formula over the photon and the particle solid angles relative to the magnetic
field direction. The method can easily be extended to a larger number of
harmonics. We also derive spectral fits of thermal emission line plasmas at
non-relativistic and trans-relativistic temperatures extending previous
parameterisations.


title: Study of the angular resolution of the ARGO-YBJ detector

abstract:
  The determination of the arrival direction of gamma-induced air showers in
the ARGO-YBJ experiment has been investigated using different algorithms in the
reconstruction procedure. The calculation has been performed, as a function of
pad multiplicity, for different primary energies. The performance of a conical
correction to the shower front with a suitable fixed cone slope is discussed.


title: Identification of showers with the core outside the ARGO-YBJ detector

abstract:
  In this paper we present a procedure able to identify and reject showers with
the core outside the ARGO-YBJ carpet boundaries. The efficiency of this method
is investigated for different primary energies and fiducial areas. A comparison
of the results for gamma and proton induced showers is also presented.


title:
XMM-Newton observations of three short period polars: V347 Pav, GG Leo
  and EU UMa

abstract:
  We present phase-resolved XMM_Newton data of three short period polars: V347
Pav, GG Leo and EU UMa. All three systems show one dominant accretion region
which is seen for approximately half of the orbital cycle. GG Leo shows a
strong dip feature in its X-ray and UV light curves which is due to absorption
of X-rays from the accretion site by the accretion stream. The emission in the
case of EU UMa is dominated by soft X-rays: its soft/hard X-ray ratio is
amongst the highest seen in these objects. In contrast, GG Leo and V347 Pav
shows a ratio consistent with that predicted by the standard shock model. We
infer the mass of the white dwarf and explore the affect of restricting the
energy range on the derived parameters.


title: Protoneutron Star Winds

abstract:
  Neutrino-driven winds are thought to accompany the Kelvin-Helmholtz cooling
phase of nascent protoneutron stars in the first seconds after a core-collapse
supernova. These outflows are a likely candidate as the astrophysical site for
rapid neutron-capture nucleosynthesis (the r-process). In this chapter we
review the physics of protoneutron star winds and assess their potential as a
site for the production of the heavy r-process nuclides. We show that spherical
transonic protoneutron star winds do not produce robust $r$-process
nucleosynthesis for `canonical' neutron stars with gravitational masses of 1.4
M_sun and coordinate radii of 10 km. We further speculate on and review some
aspects of neutrino-driven winds from protoneutron stars with strong magnetic
fields.


title: Color Variability of Asteroids in SDSS Moving Object Catalog

abstract:
  We report a detection of statistically significant color variations for a
sample of 7,531 multiply observed asteroids that are listed in the Sloan
Digital Sky Survey Moving Object Catalog. Using 5-band photometric observations
accurate to ~0.02 mag, we detect color variations in the range 0.06-0.11 mag
(rms). These variations appear uncorrelated with asteroids physical
characteristics such as diameter (in the probed 1-10 km range), taxonomic
class, and family membership. Despite such a lack of correlation, which implies
a random nature for the cause of color variability, a suite of tests suggest
that the detected variations are not instrumental effects. In particular, the
observed color variations are incompatible with photometric errors, and, for
objects observed at least four times, the color change in the first pair of
observations is correlated with the color change in the second pair. These
facts strongly suggest that the observed effect is real, and also indicate that
for some asteroids color variations are larger than for others. The detected
color variations can be explained as due to inhomogeneous albedo distribution
over an asteroid surface. Although relatively small, these variations suggest
that fairly large patches with different color than their surroundings exist on
a significant fraction of asteroids. This conclusion is in agreement with
spatially resolved color images of several large asteroids obtained by NEAR
spacecraft and HST.


title:
High-Resolution Mid-Infrared Observations of High Mass Protostellar
  Objects

abstract:
  This article presents a review of all high-resolution ground-based
mid-infrared observations of high mass protostellar objects (HMPOs) to date. An
introduction to the characteristics of HMPOs and their relationship to the hot
molecular core phase of massive star formation is outlined. I explain why
observations in the mid-infrared of these types of sources are important, and
in particular why high-resolution observations are needed. A summary is given
of the earliest mid-infrared detections of HMPOs, followed by a detailed
account of the most recent observations.


title:
In-Flight Calibration of the Chandra High Energy Transmission Grating
  Spectrometer

abstract:
  We present results from in-flight calibration of the High Energy Transmission
Grating Spectrometer (HETGS) on the Chandra X-ray Observatory. Basic grating
assembly parameters such as orientation and average grating period were
measured using emission line sources. These sources were also used to determine
the locations of individual CCDs within the flight detector. The line response
function (LRF) was modeled in detail using an instrument simulator based on
pre-flight measurements of the grating alignments and periods. These LRF
predictions agree very well with in-flight observations of sources with narrow
emission lines. Using bright continuum sources, we test the consistency of the
detector quantum efficiencies by comparing positive orders to negative orders.


title: New contribution to WIMP-nucleus scattering

abstract:
  A weakly-interacting massive particle (WIMP) is perhaps the most promising
candidate for the dark matter in the Galactic halo. The WIMP detection rate in
laboratory searches is fixed by the cross section for elastic WIMP-nucleus
scattering. Here we calculate the contribution to this cross section from
two-nucleon currents from pion exchange in the nucleus, and show that it may in
some cases be comparable to the one-nucleon current that has been considered in
prior work, and perhaps help resolve the discrepancies between the various
direct dark-matter search experiments. We provide simple expressions that allow
these new contributions to be included in current calculations.


title:
Can Non-Gaussian Cosmological Models Explain the WMAP's High Optical
  Depth for Reionization?

abstract:
  The first-year Wilkinson Microwave Anisotropy Probe data suggest a high
optical depth for Thomson scattering of 0.17 +/- 0.04, implying that the
universe was reionized at an early epoch, z ~ 20. Such early reionization is
likely to be caused by UV photons from first stars, but it appears that the
observed high optical depth can be reconciled within the standard structure
formation model only if star-formation in the early universe was extremely
efficient. With normal star-formation efficiencies, cosmological models with
non-Gaussian density fluctuations may circumvent this conflict as high density
peaks collapse at an earlier epoch than in models with Gaussian fluctuations.
We study cosmic reionization in non-Gaussian models and explore to what extent,
within available constraints, non-Gaussianities affect the reionization
history. For mild non-Gaussian fluctuations at redshifts of 30 to 50, the
increase in optical depth remains at a level of a few percent and appears
unlikely to aid significantly in explaining the measured high optical depth. On
the other hand, within available observational constraints, increasing the
non-Gaussian nature of density fluctuations can easily reproduce the optical
depth and may remain viable in underlying models of non-Gaussianity with a
scale-dependence.


title: The Wisconsin H-Alpha Mapper Northern Sky Survey

abstract:
  The Wisconsin H-Alpha Mapper (WHAM) has surveyed the distribution and
kinematics of ionized gas in the Galaxy above declination -30 degrees. The WHAM
Northern Sky Survey (WHAM-NSS) has an angular resolution of one degree and
provides the first absolutely-calibrated, kinematically-resolved map of the
H-Alpha emission from the Warm Ionized Medium (WIM) within ~ +/-100 km/s of the
Local Standard of Rest. Leveraging WHAM's 12 km/s spectral resolution, we have
modeled and removed atmospheric emission and zodiacal absorption features from
each of the 37,565 spectra. The resulting H-Alpha profiles reveal ionized gas
detected in nearly every direction on the sky with a sensitivity of 0.15 R (3
sigma). Complex distributions of ionized gas are revealed in the nearby spiral
arms up to 1-2 kpc away from the Galactic plane. Toward the inner Galaxy, the
WHAM-NSS provides information about the WIM out to the tangent point down to a
few degrees from the plane. Ionized gas is also detected toward many
intermediate velocity clouds at high latitudes. Several new H II regions are
revealed around early B-stars and evolved stellar cores (sdB/O). This work
presents the details of the instrument, the survey, and the data reduction
techniques. The WHAM-NSS is also presented and analyzed for its gross
properties. Finally, some general conclusions are presented about the nature of
the WIM as revealed by the WHAM-NSS.


title: Unraveling the cooling trend of the Soft Gamma Repeater, SGR 1627-41

abstract:
  SGR 1627-41 was discovered in 1998 after a single active episode which lasted
\~6 weeks. We report here our monitoring results of the decay trend of the
persistent X-ray luminosity of the source during the last 5 years. We find an
initial temporal power law decay with index 0.47, reaching a plateau which is
followed by a sharp (factor of ten) flux decline ~800 days after the source
activation. The source spectrum is best described during the entire period by a
single power law with high absorption (N_H=9.0(7)x10^(22) cm^(-2)); the
spectral index, however, varies dramatically between 2.2-3.8 spanning the
entire range for all known SGR sources. We discuss the cooling behavior of the
neutron star assuming a deep crustal heating initiated by the burst activity of
the source during 1998.


title: Galactic Winds: Near and Far

abstract:
  Multiwavelength data on star-forming galaxies provide strong evidence for
large-scale galactic winds in both nearby and distant objects. The results from
recent ground-based and space-borne programs are reviewed. The impact of these
winds on the host galaxies and the surrounding environment is discussed in the
context of galaxy evolution.


title: Chemical abundances in Terzan 7 from UVES spectra

abstract:
  We present chemical abundances for Mg, Si, Ca and Fe for three red giants in
the sparse globular cluster Terzan 7, physically associated to the Sagittarius
Dwarf Spheroidal Galaxy (Sgr dSph), which is presently being tidally disrupted
by the Milky Way. The data has been obtained with VLT-UVES and show a mean
[Fe/H]=-0.57, with solar alpha content, mean [alpha/Fe]=-0.03. This enforces
Ter 7's membership to the Sgr dSph system, which shows a similar pattern of
abundance.


title: Sgr dSph: a bridge between Dwarf Galaxies and DLAs?

abstract:
  We present abundances for 12 giants in the Sagittarius Dwarf Spheroidal
Galaxy (Sgr dSph) obtained from VLT - UVES spectra. Moving on a short period,
polar orbit around the Milky Way, the Sgr dSph is undergoing tidal disruption
and will eventually dissolve in the Halo.Our sample is dominated by a metal
rich, alpha-element-poor population, indicative of long chemical processing of
the dSph gas during a slow, probably bursting star formation history. This
population is the most metal-rich ever observed in a Dwarf Galaxy of the Local
Group, and has the lowest alpha-element content. Placing the known abundances
of the LG dwarfs on the [alpha/Fe] vs. [Fe/H] plane allows now to recognize a
well defined evolutive sequence, different from the one followed by the MW disk
stars, but apparently superimposed to the one followed by many of the Damped
Lyman Alpha systems.


title:
The Standard Candle Method for Type II Supernovae and the Hubble
  Constant

abstract:
  The "standard candle method" for Type II plateau supernovae produces a Hubble
diagram with a dispersion of 0.3 mag, which implies that this technique can
produce distances with a precision of 15%. Using four nearby supernovae with
Cepheid distances I find Ho(V)=75+/-7, and Ho(I)=65+/-12.


title: Hadronic gamma-ray emission from windy microquasars

abstract:
  The jets of microquasars with high-mass stellar companions are exposed to the
dense matter field of the stellar wind. We present estimates of the gamma-ray
emission expected from the jet-wind hadronic interaction and we discuss the
detectability of the phenomenon at high energies. The proposed mechanism could
explain some of the unidentified gamma-ray sources detected by EGRET instrument
on the galactic plane.


title: History of Astrophysics in Antarctica - A Brief Overview

abstract:
  On examining the historical development of astrophysical science at the
bottom of the world from the early 20th century until today we find three
temporally overlapping eras of which each has a rather distinct beginning.
These are the eras of Astrogeology, High Energy Astrophysics and Photon
Astronomy. A full version of this paper will be submitted to PASA.


title: The old open clusters Saurer A, B and C revisited

abstract:
  We report on deep (V $\approx$ 24.0) $VI$ CCD photometry of 3 fields centered
in the regions of the old open clusters Saurer A, B and C. In the case of
Saurer A, which is considered one of the oldest known open cluster, we also
provide a comparison field. From the analysis of the photometry we claim that
Saurer A is as old as M 67 ($\approx$ 5 Gyrs), but more metal poor (Z=0.008).
Moreover it turns out to be the open cluster with the largest galactocentric
distance so far detected. As for Saurer B, it closely resembles NGC 2158, and
indeed is of intermediate-age (1.8-2.2 Gyrs) and significantly reddened. In
this case we revise both the age and the distance with respect to previous
studies, but we are not able to clearly establish the cluster metal abundance.
Finally, Saurer C has an age of about 2 Gyrs, but we emphasize that the precise
determination of its properties is hampered by the heavy fieldstars
contamination.


title: The stellar environment of SMC N81

abstract:
  We present near infrared JHK imaging of the Small Magellanic Cloud compact H
II region N81 using the ISAAC camera at the ESO Very Large Telescope (Antu).
Our analysis of the stellar environment of this young massive star region
reveals the presence of three new stellar populations in the surrounding field
which are mainly composed of low mass stars. The main population is best fitted
by evolutionary models for about 2 solar mass stars with an age of 1 Gyr. We
argue that these populations are not physically associated with the H II region
N81. Instead they are the result of a number of low mass star forming events
through the depth of the SMC south of its Shapley's wing. The populations can
rather easily be probed due to the low interstellar extinction in that
direction.


title: Ultraviolet Background Radiation from Cosmic Structure Formation

abstract:
  We calculate the contribution to the ultraviolet background (UVB) from
thermal emission from gas shock heated by cosmic structure formation. Our main
calculation is based on an updated version of Press-Schechter theory. It is
consistent with a more empirical estimate based on the observed properties of
galaxies and the observed cosmic star formation history. Thermal UVB emission
is characterized by a hard spectrum extending well beyond 4 Ry. The bulk of the
radiation is produced by objects in the mass range 10^11-13 M_solar, i.e. large
galaxies and small groups. We compute a composite UVB spectrum due to QSO,
stellar and thermal components. The ratio of the UVB intensities at the H and
He Lyman limits increases from 60 at z=2 to more than 300 at z=6. A comparison
of the resulting photoionization rates to the observed Gunn-Peterson effect at
high redshifts constrains the escape fraction of ionizing photons from galaxies
to be less than a few percent. Near 1 Ry, thermal and stellar emission are
comparable amounting to about 10 %, 20 % and 35 % of the total flux at
redshifts of 3, 4.5 and higher, respectively. However, near the ionization
threshold for HeII, the thermal contribution is much stronger. It is comparable
to the QSO intensity already at redshift ~3 and dominates at redshifts above 4.
Thermal photons alone are enough to produce and sustain HeII reionization
already at z~6. We discuss the possible implications of our results for the
thermal history of the intergalactic medium, in particular for HeII
reionization.


title: Global asymptotic solutions for non-relativistic MHD jets and winds

abstract:
  We present general and global analytical solutions, valid from pole to
equator, for the asymptotic structure of non-relativistic, rotating,
stationary, axisymmetric, polytropic, unconfined, perfect MHD winds. The
asymptotic structure of such winds consists of field-regions virtually devoid
of poloidal current. We show that an Hamilton-Jacobi equation, or equivalently
a Grad-Shafranov equation, gives the asymptotic structure in the field
regions.These field regions are bordered by current-carrying boundary layers
around the polar axis and near null magnetic surfaces. The solution is given in
the form of matched asymptotics separately valid outside and inside these
boundary layers. The polar boundary layer is pressure-supported against the
pinching force exerted by the axial poloidal current and has the structure of a
current pinch, while the null-surface boundary layers have the structure of
current sheet pinches.For winds which are kinetic-energy dominated at infinity
we derive WKBJ analytic solutions whose magnetic surfaces focus into
paraboloids. The current slowly weakens as the inverse of the logarithm of the
distance to the wind source while the axial plasma density falls-off as a
negative power of this logarithm.For winds carrying Poynting flux at large
distances the solutions asymptotically approach to nested cylindrical and
conical magnetic surfaces.


title: State transitions in the 2001/2002 outburst of XTE J1650-500

abstract:
  We present a study of the X-ray transient and black hole candidate XTE
J1650-500 during its 2001/2002 outburst. The source made two state transitions
between the hard and soft states, at luminosity levels that differed by a
factor of ~5-10. The first transition, between hard and soft, lasted for ~30
days and showed two parts; one part in which the spectral properties evolve
smoothly away from the hard state and another that we identify as the 'steep
power law state'. The two parts showed different behavior of the Fe K emission
line and QPO frequencies. The second transition, from soft to hard, lasted only
\~15 days and showed no evidence of the presence of the 'steep power law
state'. Comparing observations from the early rise and the decay of the
outburst, we conclude that the source can be in the hard state in a range of
more 10^4 in luminosity. We briefly discuss the state transitions in the
framework of a two-flow model.


title: 67P/Churyumov-Gerasimenko - potential target for the Rosetta mission

abstract:
  An influence of the non-gravitational effects on the motion of short-period
comet 67P/Churyumov-Gerasimenko is investigated. It was found that the normal
component of the non-gravitational force exceeds the transverse one and a model
of the motion including A_1, A_2, A_3 better fits the observations than model
neglecting A_3. Assuming asymmetry in g(r) with respect to the perihelion the
large value of displacement \tau was derived (about 34 days), and very small
negative value of transverse component A_2 was obtained. The models of rotating
non-spherical nucleus also suggest the large shift of light curve with respect
to perihelion (\tau greater than 30 days). The forced precession model of 67P
with \tau = 34 days gives a prolate spheroidal shape of the rotating nucleus
with axial ratio R_b/R_a = 1.16, rotational period to equatorial radius
P_{rot}/R_a = 4.6\pm 1.4 hrs/km, and torque factor f_{tor}=3\cdot 10^5 day/AU.
The much larger \tau = 54 days gives distinctly prolate shape of nucleus with
axial ratio R_b/R_a = 1.71. The orientation of spin axis of the nucleus and its
evolution are presented. The past and the future dynamical evolution of comet
67P is also widely discussed.


title:
The Formation of Massive Stars by Accretion Through Trapped Hypercompact
  HII Regions

abstract:
  The formation of massive stars may take place at relatively low accretion
rates over a long period of time if the accretion can continue past the onset
of core hydrogen ignition. The accretion may continue despite the formation of
an ionized HII region around the star if the HII region is small enough that
the gravitational attraction of the star dominates the thermal pressure of the
HII region. The accretion may continue despite radiation pressure acting
against dust grains in the molecular gas if the momentum of the accretion flow
is sufficient to push the dust grains through a narrow zone of high dust
opacity at the ionization boundary and into the HII region where the dust is
sublimated. This model of massive star formation by continuing accretion
predicts a new class of gravitationally-trapped, long-lived hypercompact HII
regions. The observational characteristics of the trapped hypercompact HII
regions can be predicted for comparison with observations.


title: Global asymptotic solutions for relativistic MHD jets and winds

abstract:
  We consider relativistic, stationary, axisymmetric, polytropic, unconfined,
perfect MHD winds, assuming their five lagrangian first integrals to be known.
The asymptotic structure consists of field-regions bordered by boundary layers
along the polar axis and at null surfaces, such as the equatorial plane, which
have the structure of charged column or sheet pinches supported by plasma or
magnetic poloidal pressure. In each field-region cell, the proper current
(defined here as the ratio of the asymptotic poloidal current to the asymptotic
Lorentz factor) remains constant. Our solution is given in the form of matched
asymptotic solutions separately valid outside and inside the boundary layers.
An Hamilton-Jacobi equation, or equivalently a Grad-Shafranov equation, gives
the asymptotic structure in the field-regions of winds which carry Poynting
flux to infinity. An important consistency relation is found to exist between
axial pressure, axial current and asymptotic Lorentz factor. We similarly
derive WKB-type analytic solutions for winds which are kinetic-energy dominated
at infinity and whose magnetic surfaces focus to paraboloids. The density on
the axis in the polar boundary column is shown to slowly fall off as a negative
power of the logarithm of the distance to the wind source. The geometry of
magnetic surfaces in all parts of the asymptotic domain, including boundary
layers, is explicitly deduced in terms of the first-integrals.


title:
Birth rates of different types of neutron star and possible evolutions
  of these objects

abstract:
  We estimate the spatial densities of different types of neutron star near the
Sun. It is shown that the distances of dim isolated thermal neutron stars must
be on average about 300-400 pc. The combined birth rate of these sources
together with radio pulsars and dim radio quiet neutron stars can be a little
more than the supernova rate as some of the dim isolated thermal neutron stars
can be formed from dim radio quiet neutron stars and radio pulsars. Some of
these sources must have relations with anomalous X-ray pulsars and soft gamma
repeaters. In order to understand the locations of different types of neutron
star on the P-\.{P} diagram it is also necessary to take into account the
differences in the masses and the structures of neutron stars.


title: Stellar population synthesis at the resolution of 2003

abstract:
  We present a new model for computing the spectral evolution of stellar
populations at ages between 100,000 yr and 20 Gyr at a resolution of 3 A across
the whole wavelength range from 3200 to 9500 A for a wide range of
metallicities. These predictions are based on a newly available library of
observed stellar spectra. We also compute the spectral evolution across a
larger wavelength range, from 91 A to 160 micron, at lower resolution. The
model incorporates recent progress in stellar evolution theory and an
observationally motivated prescription for thermally-pulsing stars on the
asymptotic giant branch. The latter is supported by observations of surface
brightness fluctuations in nearby stellar populations. We show that this model
reproduces well the observed optical and near-infrared colour-magnitude
diagrams of Galactic star clusters of various ages and metallicities.
Stochastic fluctuations in the numbers of stars in different evolutionary
phases can account for the full range of observed integrated colours of star
clusters in the Magellanic Clouds. The model reproduces in detail typical
galaxy spectra from the Early Data Release (EDR) of the Sloan Digital Sky
Survey (SDSS). We exemplify how this type of spectral fit can constrain
physical parameters such as the star formation history, metallicity and dust
content of galaxies. Our model is the first to enable accurate studies of
absorption-line strengths in galaxies containing stars over the full range of
ages. Using the highest-quality spectra of the SDSS EDR, we show that this
model can reproduce simultaneously the observed strengths of those Lick indices
that do not depend strongly on element abundance ratios [abridged].


title:
Late-time Entropy Production from Scalar Decay and Relic Neutrino
  Temperature

abstract:
  Entropy production from scalar decay in the era of low temperatures after
neutrino decoupling will change the ratio of the relic neutrino temperature to
the CMB temperature, and, hence, the value of N_eff, the effective number of
neutrino species. Such scalar decay is relevant to reheating after thermal
inflation, proposed to dilute massive particles, like the moduli and the
gravitino, featuring in supersymmetric and string theories. The effect of such
entropy production on the relic neutrino temperature ratio is calculated in a
semi-analytic manner, and a recent lower bound on this ratio, obtained from the
WMAP satellite and 2dF galaxy data, is used to set a lower bound of ~ 1.5 x
10^-23 Gev on the scalar decay constant, corresponding to a reheating
temperature of about 3.3 Mev.


title: Morphological Evolution of Dwarf Galaxies in the Local Group

abstract:
  The dwarf galaxies of the Local Group can be separated in three morphological
groups: irregular, elliptical and spheroidal. As in the large galaxy clusters,
there seems to be a morphology-position relationship: irregular galaxies are
preferentially found in the outskirts (low density regions) of the Local Group,
whereas dwarf ellipticals and spheroidals are more frequent in the central,
high density regions. To cast light on the nature and origin of dwarf galaxies
in the Local Group, Mayer et al.(2001) have suggested that a dwarf irregular
galaxy tidally interacting with a galaxy of much larger mass may be re-shaped
into a dwarf spheroidal or elliptical object. In this paper we check by means
of N-Body Tree-SPH simulations whether this is possible for a selected sample
of galaxies of the Local Group. Using the best data available in literature to
fix the dynamical and kinematical status of a few dwarf galaxies in the Local
Group, we follow the evolution of an ideal satellite, which supposedly started
as an irregular object during its orbital motion around the Milky Way. We find
that the tidal interactions with the Milky Way remove a large fraction of the
mass of the dwarf irregular and gradually reshape it into a spherical object.


title:
The Connection Between Radio Quiet AGN and the High/Soft State of X-Ray
  Binaries

abstract:
  A large sample of AGN studied here shows a ``quenching'' of the radio
emission occurs when the luminosity is at a few percent to about 10% of the
Eddington rate, just as is seen in the high/soft state of X-ray binaries. The
result holds even when the sample of AGN includes no Narrow Line Seyfert 1
galaxies (the systems most commonly suggested to be the analog of the high/soft
state). This adds substantially to the body of evidence that AGN show the same
spectral state phenomenology and related disc-jet coupling as the stellar mass
accreting black holes. That the power law correlation between X-ray and radio
luminosity is the same in both AGN and X-ray binaries and extends below
$10^{-7} L_{EDD}$ strengthens the argument that there is no fundamental
difference between the low/hard state and the so-called quiescent state in
X-ray binaries. We also discuss possible reasons for the scatter in the radio
to X-ray luminosity correlation in the AGN.


title: Sulphur chemistry in the envelopes of massive young stars

abstract:
  The sulphur chemistry in nine regions in the earliest stages of high-mass
star formation is studied through single-dish submillimeter spectroscopy. The
line profiles indicate that 10-50% of the SO and SO2 emission arises in
high-velocity gas, either infalling or outflowing. For the low-velocity gas,
excitation temperatures are 25 K for H2S, 50 K for SO, H2CS, NS and HCS+, and
100 K for OCS and SO2, indicating that most observed emission traces the outer
parts (T<100 K) of the molecular envelopes, except high-excitation OCS and SO2
lines. Abundances in the outer envelopes, calculated with a Monte Carlo
program, using the physical structures of the sources derived from previous
submillimeter continuum and CS line data, are ~10^-8 for OCS, ~10^-9 for H2S,
H2CS, SO and SO2, and ~10^-10 for HCS+ and NS. In the inner envelopes (T>100 K)
of six sources, the SO2 abundance is enhanced by factors of ~100-1000. This
region of hot, abundant SO2 has been seen before in infrared absorption, and
must be small, <~ 0.2 arcsec (180 AU radius). The derived abundance profiles
are consistent with models of envelope chemistry which invoke ice evaporation
at T~100$ K. Shock chemistry is unlikely to contribute. A major sulphur carrier
in the ices is probably OCS, not H2S as most models assume. The
source-to-source abundance variations of most molecules by factors of ~10 do
not correlate with previous systematic tracers of envelope heating. Without
observations of H2S and SO lines probing warm (>~ 100 K) gas, sulphur-bearing
molecules cannot be used as evolutionary tracers during star formation.


title:
Outflow-Confined HII Regions and the Formation of Massive Stars by
  Accretion

abstract:
  If massive stars form by disk accretion, then bipolar outflows should be
generated as in the case of low-mass star formation. High accretion rates lead
to high outflow rates and make the wind density very large near the protostar.
We therefore predict that massive protostars have very small, jet-like HII
regions confined by their outflows; we identify these HII regions with
"hypercompact" (<0.01 pc) HII regions. Their lifetime is approximately equal to
the accretion timescale (~10^5 yr), much longer than the sound-crossing and
dynamical timescales of the ionized region. We present an analytic description
of the density distribution of the outflow, relate the overall mass loss rate
to the accretion rate, and normalize to values appropriate to massive
protostars. For a given ionizing luminosity, we calculate the extent of the HII
region and its radio spectrum. A detailed comparison is made with observations
of radio source "I" in the Orion Hot Core. The spectra and morphologies of many
other sources are broadly consistent with this model. We argue that confinement
of ionization allows disk and equatorial accretion to continue up to high
masses, potentially overcoming a major difficulty of standard accretion models.


title:
INTEGRAL observations of SS433, a supercritically accreting microquasar
  with hard spectrum

abstract:
  Observations of SS433 by INTEGRAL carried out in March -- May 2003 are
presented. SS433 is evidently detected on the INTEGRAL images of the
corresponding sky region in the energy bands 25-50 and 50-100 keV. The
precessional variability of the hard X-ray flux is clearly seen. The X-ray
eclipse caused by the binary orbital motion is also detected. A possible origin
of the hard continuum is briefly discussed.


title:
Implications of Cosmological Gamma-Ray Absorption II. Modification of
  gamma-ray spectra

abstract:
  Bearing on the model for the time-dependent metagalactic radiation field
developed in the first paper of this series, we compute the gamma-ray
attenuation due to pair production in photon-photon scattering. Emphasis is on
the effects of varying the star formation rate and the fraction of UV radiation
assumed to escape from the star forming regions, the latter being important
mainly for high-redshift sources. Conversely, we investigate how the
metagalactic radiation field can be measured from the gamma-ray pair creation
cutoff as a function of redshift, the Fazio-Stecker relation. For three
observed TeV-blazars (Mkn501, Mkn421, H1426+428) we study the effects of
gamma-ray attenuation on their spectra in detail.


title:
Mapping the Circumstellar Environment of T Tauri with Fluorescent H_2
  Emission

abstract:
  We have obtained three long-slit, far UV spectra of the pre-main sequence
system T Tauri. These HST/STIS spectra show a strong and variable on-source
spectrum composed of both fluoresced H_2 and stellar chromospheric lines.
Extended H_2 emission is seen up to 10" from the T Tau system. The on-source
and extended H_2 are both pumped by H I Lyman alpha. The on-source H_2 is
pumped by the red wing of a broad, self-absorbed Ly-alpha line, while the
progressions seen in the extended gas are pumped from near line center. This
suggests that the extended H_2 is pumped locally, and not by the stellar
Ly-alpha line. The H_2 to the north and west coincides with the evacuated
cavity bounded by the optical reflection nebulosity; to the south the extended
H_2 coincides with the HH 255 outflow from the embedded infrared companion T
Tau S. The spatial profile of the extended gas shows a prominent dip coincident
with the position of T Tau S. This may be absorption by a disk associated with
T Tau S. There is no evidence for absorption by a disk surrounding T Tau N
large enough to obscure T Tau S.


title:
Kinetic energy flux versus Poynting flux in MHD winds and jets: the
  intermediate regime

abstract:
  We show that the formal asymptotic limit for all rotating polytropic
axisymmetric perfect MHD flows is a kinetic energy dominated wind which
collimates to paraboloids around the symmetry axis. We reach this result by
showing that another, a priori possible, solution with finite Poynting flux can
be excluded on the following physical grounds: (1) the wind velocity does not
exceed the fast mode speed everywhere and (2) the circumpolar current increases
with distance from the source.We show that asymptotic hoop stress collimation
is mathematically robust and we give strong arguments why recent
anti-collimation claims are not correct. However, in practice, due to the very
slow logarithmic decline of the circumpolar current with increasing distance
from the source, there is a broad intermediate regime with significant Poynting
flux. This intermediate regime, rather than the mathematically exact asymptotic
regime, may well apply along the finite length of the jet. We briefly discuss
peculiarities that would be associated with Poynting jets in the intermediate
regime. Force-free initial conditions in the near field are most likely to
produce such jets, in which most of the energy flux is electromagnetic.


title: Synchrotron Radiation and Quantum Gravity

abstract:
  Photons may evade a synchrotron radiation constraint on quantum gravity by
violating the equivalence principle.


title: Digital Deblurring of CMB Maps II: Asymmetric Point Spread Function

abstract:
  In this second paper in a series dedicated to developing efficient numerical
techniques for the deblurring Cosmic Microwave Background (CMB) maps, we
consider the case of asymmetric point spread functions (PSF). Although
conceptually this problem is not different from the symmetric case, there are
important differences from the computational point of view because it is no
longer possible to use some of the efficient numerical techniques that work
with symmetric PSFs. We present procedures that permit the use of efficient
techniques even when this condition is not met. In particular, two methods are
considered: a procedure based on a Kronecker approximation technique that can
be implemented with the numerical methods used with symmetric PSFs but that has
the limitation of requiring only mildly asymmetric PSFs. The second is a
variant of the classic Tikhonov technique that works even with very asymmetric
PSFs but that requires discarding the edges of the maps. We provide details for
efficient implementations of the algorithms. Their performance is tested on
simulated CMB maps.


title:
Tests for supernova explosion models: from light curves to X-ray
  emission of supernova remnants

abstract:
  The successful theoretical supernova explosion models should be able to
explain any features of the emission from supernovae at any evolutionary stage.
We check several models from two different points of view. With the
multi-frequency radiation hydro code STELLA we calculate gamma-ray, bolometric
and broad-band UBVI light curves. Then we use the same models to calculate the
emission from young supernova remnants.
  Here we present new plots for gamma-ray luminosity from several SN Ia models
and recomputations of bolometric and UBVRI light curves of model 13C for SN
1993J.


title: Extremely red galaxies in the Phoenix Deep Survey

abstract:
  The Phoenix Deep Survey (PDS) is a multiwavelength survey based on deep 1.4
GHz radio observations used to identify a large sample of star forming galaxies
to z=1. Here we present an exploration of the evolutionary constraints on the
star-forming population imposed by the 1.4 GHz source counts, followed by an
analysis of the average properties of extremely red galaxies in the PDS, by
using the "stacking" technique.


title: The diameter and evolutionary state of Procyon A

abstract:
  We report the angular diameter measurement obtained with the VINCI/VLTI
instrument on the nearby star Procyon A (alpha CMi A, F5IV-V), at a relative
precision of +/- 0.9%. We obtain a uniform disk angular diameter in the K band
of UD = 5.376 +/- 0.047 mas and a limb darkened value of LD = 5.448 +/- 0.053
mas. Together with the Hipparcos parallax, this gives a linear diameter of
2.048 +/- 0.025 D_sun. We use this result in combination with spectroscopic,
photometric and asteroseismic constraints to model this star with the CESAM
code. One set of modeling parameters that reproduces the observations within
their error bars are an age of 2314 Myr, an initial helium mass fraction Y_i =
0.301 and an initial mass ratio of heavy elements to hydrogen Z/X_i = 0.0314.
We also computed the adiabatic oscillation spectrum of our model of Procyon A,
giving a mean large frequency separation of Delta nu_0 = 54.7 microHz. This
value is in agreement with the seismic observations by Martic et al. (1999,
2001). The interferometric diameter and the asteroseismic large frequency
spacing together suggest a mass closer to 1.4 M_sun than to 1.5 M_sun. We
conclude that Procyon is currently ending its life on the main sequence, as its
luminosity class indicates.


title:
Completion of a Survey and Detailed Study of Double-Peaked Emission
  Lines in Radio-Loud AGNs

abstract:
  We report the completion of a survey of radio-loud AGNs begun in an earlier
paper, aimed finding and studying broad, double-peaked Balmer lines. We present
Ha spectra of 13 broad-lined objects (3 with double-peaked Ha profiles). The
final sample includes 106 radio-loud AGNs. 20% of the objects have Ha lines
with double peaks or twin shoulders and of these, 60% can be fitted quite well
with a model attributing the emission to a circular, relativistic, disk. We
also compare the Hb and MgII profiles of 4 objects with models of photoionized
accretion disks and find them to be in reasonable agreement. Double-peaked
emitters stand out on the basis of the following properties: (1) unusually
large contribution of starlight to the optical continuum around Ha, (2)
unusually large equivalent widths of low-ionization lines ([OI] and [SII]), (3)
unusually large [OI]/[OIII] ratios, and (4) Balmer lines on average twice as
broad as in other radio-loud AGNs. We evaluate models for the origin of the
lines and we find accretion-disk emission to be the most successful one because
it can explain the double-peaked line profiles and it also offers an
interpretation of the spectroscopic properties of these objects. Aternative
suggestions (binary broad-line regions, bipolar outflows, anisotropically
illuminated spherical broad-line regions) are unsatisfactory because (a) they
fail direct observational tests, (b) they cannot explain the unusual properties
of double-peaked emitters self-consistently, or (c) their physical foundations
appear to be unsound. We suggest that in double-peaked emitters and accretion-
powered LINERs the accretion rate is considerably lower than the Eddington rate
with the consequence that the inner accretion disk takes the form of an ion
torus and the wind that normally enshrouds the disk proper is absent.


title: XMM-Newton observations of the hot-gas atmospheres of 3C 66B and 3C 449

abstract:
  We present new XMM-Newton observations of the hot-gas environments of two
low-power twin-jet radio galaxies, 3C 66B and 3C 449, showing direct evidence
for the interactions between X-ray-emitting gas and radio plasma that are
thought to determine the large-scale radio structure of these sources. The
temperatures that we measure for the two environments are significantly higher
than those predicted by standard luminosity-temperature relations for clusters
and groups. We show that luminosity-temperature relations for radio-quiet and
radio-loud X-ray groups differ, in the sense that radio-source heating may
operate in most groups containing radio galaxies. If the radio lobes are
expanding subsonically, we find minimum ages of 3e8 years for 3C 66B, and 5e8
years for 3C 449, older than the values obtained from spectral ageing, which
would give the radio source sufficient time to heat the groups to the observed
temperatures for plausible values of the jet power. The external pressures in
the atmospheres of both radio galaxies are an order of magnitude higher than
equipartition estimates of their radio-lobe pressures, confirming that the
radio lobes are either out of equipartition or require a pressure contribution
from non-radiating particles. Constraints from the level of X-ray emission we
measure from the radio lobes allow us to conclude that a departure from
equipartition must be in the direction of magnetic domination, and that the
most plausible candidates for a particle contribution to lobe pressure are
relativistic protons, an additional population of low-energy electrons, or
entrained and heated thermal material.


title:
The Helium White Dwarf orbiting the Millisecond Pulsar in the halo of
  the Globular Cluster NGC 6752

abstract:
  We have used deep high-resolution multiband images taken at the ESO Very
Large Telescope to identify the optical binary companion to the millisecond
pulsar (PSR J1911-5958A) located in the halo of the Galactic Globular Cluster
NGC6752. The object turns out to be a blue star whose position in the Color
Magnitude Diagram is consistent with the cooling sequence of a low mass
(M~0.17-0.20Mo), low metallicity Helium white dwarf (He-WD) at the cluster
distance. This is the second He-WD which has been found to orbit a millisecond
pulsar in GGCs. Curiously both objects have been found to lie on the same mass
He-WD cooling sequence. The anomalous position of PSR J1911-5958A with respect
to the globular cluster center (~6') suggested that this system has recently
(<1 Gyr) been ejected from the cluster core as the result of a strong dynamical
interaction. The data presented here allows to constrain the cooling age of the
companion within a fairly narrow range (~1.2-2.8 Gyr), therefore suggesting
that such dynamical encounter must have acted on an already recycled
millisecond pulsar.


title: Hot Molecular Cores and High-Mass Star Formation

abstract:
  This review covers hot cores in the context of high-mass star formation.
After giving an overview of chemical processes and diversity during high-mass
star formation, it reviews the `warm envelope' phase which probably precedes
the formation of hot cores. Some recent determinations of the cosmic-ray
ionization rate are discussed, as well as recent evidence for hot cores around
low-mass stars. Routes for future hot core research are outlined.


title:
Star Cluster Formation and Evolution in the Dwarf Starburst Galaxy NGC
  1569

abstract:
  We analyse multi-wavelength Hubble Space Telescope (HST) observations of a
large number of star clusters in the nearby (post-) starburst dwarf galaxy NGC
1569. Their spectral energy distributions (SEDs) cover at least the wavelength
range from U to I in equivalent HST filters, in most cases supplemented by
near-infrared data. Using our most up-to-date evolutionary synthesis models of
the Goettingen GALEV code we determine ages, metallicities, extinction values
and masses for each individual cluster robustly and independently. We confirm
the youth of most of these objects. The majority were formed in a very intense
starburst starting around 25 Myr ago. While there are two prominent ``super
star clusters'' present in this galaxy, with masses of (5-16) * 10^5 Msun,
almost all remaining clusters are significantly less massive than an average
Milky Way globular cluster, and are generally consistent with open cluster-type
objects. We determine the cluster mass function from individual cluster masses
derived by scaling the model SEDs of known mass to the observed cluster SEDs
for each individual cluster. We find signs of a change in the cluster mass
function as the burst proceeds, which we attribute to the special conditions of
star cluster formation in this starburst dwarf galaxy environment.


title:
High-Resolution Continuum Imaging at 1.3 and 0.7 cm of the W3 IRS 5
  Region

abstract:
  High-resolution images of the hypercompact HII regions (HCHII) in W3 IRS 5
taken with the Very Large Array (VLA) at 1.3 and 0.7 cm are presented. Four
HCHII regions were detected with sufficient signal-to-noise ratios to allow the
determination of relevant parameters such as source position, size and flux
density. The sources are slightly extended in our ~0.2 arcsecond beams; the
deconvolved radii are less than 240 AU. A comparison of our data with VLA
images taken at epoch 1989.1 shows proper motions for sources IRS 5a and IRS
5f. Between 1989.1 and 2002.5, we find a proper motion of 210 mas at a position
angle of 12 deg for IRS 5f and a proper motion of 190 mas at a position angle
of 50 deg for IRS 5a. At the assumed distance to W3 IRS 5, 1.83 +/- 0.14 kpc,
these offsets translate to proper motions of ~135 km/s and ~122 km/s$
respectively. These sources are either shock ionized gas in an outflow or
ionized gas ejected from high mass stars. We find no change in the positions of
IRS 5d1/d2 and IRS 5b; and we show through a comparison with archival NICMOS
2.2 micron images that these two radio sources coincide with the infrared
double constituting W3 IRS 5. These sources contain B or perhaps O stars. The
flux densities of the four sources have changed compared to the epoch 1989.1
results. In our epoch 2002.5 data, none of the spectral indicies obtained from
flux densities at 1.3 and 0.7 cm are consistent with optically thin free-free
emission; IRS 5d1/d2 shows the largest increase in flux density from 1.3 cm to
0.7 cm. This may be an indication of free-free optical depth within an ionized
wind, a photoevaporating disk, or an accretion flow. It is less likely that
this increase is caused by dust emission at 0.7 cm.


title: Multi-color observations of Young Star Clusters

abstract:
  We present a new set of evolutionary synthesis models of our GALEV code,
specifically developed to include the gaseous emission of presently forming
star clusters, in combination with an advanced tool to compare large model
grids with multi-color broad-band observations of YSC systems. Tests and first
applications are presented.


title: Young star clusters: Progenitors of globular clusters!?

abstract:
  Star cluster formation is a major mode of star formation in the extreme
conditions of interacting galaxies and violent starbursts. Young clusters are
observed to form in a variety of such galaxies, a substantial number resembling
the progenitors of globular clusters in mass and size, but with significantly
enhanced metallicity. From studies of the metal-poor and metal-rich star
cluster populations of galaxies, we can therefore learn about the violent star
formation history of these galaxies, and eventually about galaxy formation and
evolution. We present a new set of evolutionary synthesis models of our GALEV
code, with special emphasis on the gaseous emission of presently forming star
clusters, and a new tool to compare extensive model grids with multi-color
broad-band observations to determine individual cluster masses, metallicities,
ages and extinction values independently. First results for young star clusters
in the dwarf starburst galaxy NGC 1569 are presented. The mass distributions
determined for the young clusters give valuable input to dynamical star cluster
system evolution models, regarding survival and destruction of clusters. We
plan to investigate an age sequence of galaxy mergers to see dynamical
destruction effects in process.


title: Young star clusters: Metallicity tracers in external galaxies

abstract:
  Star cluster formation is a major mode of star formation in the extreme
conditions of interacting galaxies and violent starbursts. These newly-formed
clusters are built from recycled gas, pre-enriched to various levels within the
interacting galaxies. Hence, star clusters of different ages represent a fossil
record of the chemical enrichment history of their host galaxy, as well as of
the host galaxy's violent star formation history. We present a new set of
evolutionary synthesis models of our GALEV code, specifically developed to
include the gaseous emission of presently forming star clusters, and a new tool
to analyse multi-color observations with our models. First results for
newly-born clusters in the dwarf starburst galaxy NGC 1569 are presented.


title: Young star clusters: Clues to galaxy formation and evolution

abstract:
  Young clusters are observed to form in a variety of interacting galaxies and
violent starbursts, a substantial number resembling the progenitors of the
well-studied globular clusters in mass and size. By studying young clusters in
merger remnants and peculiar galaxies, we can therefore learn about the violent
star formation history of these galaxies. We present a new set of evolutionary
synthesis models of our GALEV code specifically developed to include the
gaseous emission of presently forming star clusters, and a new tool that allows
to determine individual cluster metallicities, ages, extinction values and
masses from a comparison of a large grid of model Spectral Energy Distributions
(SEDs) with multi-color observations. First results for the newly-born clusters
in NGC 1569 are presented.


title:
On the Evidence for Clustering in the Arrival Directions of AGASA's
  Ultrahigh Energy Cosmic Rays

abstract:
  Previous analyses of cosmic rays above 40 EeV observed by the AGASA
experiment have suggested that their arrival directions may be clustered.
However, estimates of the chance probability of this clustering signal vary
from 10^{-2} to 10^{-6} and beyond. It is essential that the strength of this
evidence be well understood in order to compare it with anisotropy studies in
other cosmic ray experiments. We apply two methods for extracting a meaningful
significance from this data set: one can scan for the cuts which optimize the
clustering signal, using simulations to determine the appropriate statistical
penalty for the scan. This analysis finds a chance probability of about 0.3%.
Alternatively, one can optimize the cuts with a first set of data, and then
apply them to the remaining data directly without statistical penalty. One can
extend the statistical power of this test by considering cross-correlation
between the initial data and the remaining data, as long as the initial
clustering signal is not included. While the scan is more useful in general, in
the present case only splitting the data set offers an unbiased test of the
clustering hypothesis. Using this test we find that the AGASA data is
consistent at the 8% level with the null hypothesis of isotropically
distributed arrival directions.


title:
High Angular Resolution Measurement of Ion and Neutral Spectra as a
  Probe of the Magnetic Field Structure in DR21(OH)

abstract:
  It has been suggested that under average interstellar field strengths the
cyclotron interaction between ions and magnetic fields is strong enough to
narrow the linewidth and suppress the line wings in the ion spectra. We present
evidence for the cyclotron interaction effect at arcsec scale on the velocity
dispersions in the spectra of ion/neutral molecular species in DR21(OH)
observed with the OVRO-MMA. Using a spatial resolution $\sim$ 3 times higher
than previous CSO observations by Houde et al. (2002), we show that
H$^{13}$CO$^+$ and H$^{13}$CN are coexistent at the scale of our observations
(6\arcsec). In the eastern parts of the DR21(OH) core where the dynamics is
simple, the ion linewidths are indeed narrower than the neutral linewidths with
an average ion-to-neutral linewidth ratio of 0.82$\pm$0.04. We use our results,
along with the existing Zeeman and dust/CO polarization data on small scales,
to derive the 3-D magnetic field structure. We obtain a field strength of
$0.44\pm$0.12 mG with inclination of 36\deg to the line of sight, directed
toward the observer, and a position angle of $-$75\deg in the plane of the sky.
With the full magnetic field strength derived here, we are able to conclude
that the MM1 core of DR21(OH) is magnetically supercritical; although
turbulence provides the dominant support.


title:
Creation of Electron--Positron Wind in Gamma-Ray Bursts and Its Effect
  on the Early Afterglow Emission

abstract:
  We calculate the creation of electron--positron pairs in Gamma-Ray Bursts
(GRBs) resulting from the collision between scattered and outward moving
gamma-ray photons. The number of pairs exceeds the number of ambient medium
electrons encountered by the GRB ejecta up to ~ 10^{16} cm from the center of
explosion. The shock resulting from the interaction of the ejecta with the
pair-wind may brighten the afterglow synchrotron emission during the first few
minutes. Even without this effect, the peak intensity of the optical afterglow
increases with the density of the surrounding medium. Therefore, observations
of the optical flux at early times constrain the density of the circumburst
medium. If the electron and magnetic field energies behind the forward shock
sweeping-up the pair-wind and the circumburst medium are as inferred from fits
to the broadband afterglow emission at 0.5-100 days, then the current upper
limits on the optical counterpart emission, set by the ROTSE and LOTIS
experiments, indicate that the circumburst medium within 0.01 pc is less dense
than 100 cm^{-3} or, if a wind, corresponds to a progenitor mass-loss to wind
speed ratio below 10^{-6} M_sun/yr/(1000 km/s).


title: Sagittarius Tidal Debris 90 kpc from the Galactic Center

abstract:
  A new overdensity of A-colored stars in distant parts of the Milky Way's
stellar halo, at a dereddened SDSS magnitude of g_0 = 20.3, is presented.
Identification of associated variable RR Lyrae candidates supports the claim
that these are blue horizontal branch stars. The inferred distance of these
stars from the Galactic center is 90 kpc, assuming the absolute magnitude of
these stars is M_g_0 = 0.7 and that the Sun is 8.5 kpc from the Galactic
center. The new tidal debris is within 10 kpc of same plane as other confirmed
tidal debris from the disruption of the Sagittarius dwarf galaxy, and could be
associated with the trailing tidal arm. Distances to the Sagittarius stream
estimated from M stars are about 13% smaller than our inferred distances. The
tidal debris has a width of at least 10 degrees, and is traced for more than 20
degrees across the sky. The globular cluster NGC 2419 is located within the
detected tidal debris, and may also have once been associated with the
Sagittarius dwarf galaxy.


title: The dark matter content of lensing galaxies at 1.5 R_e

abstract:
  Many gravitationally lensed quasars exhibit flux ratio "anomalies" that
cannot be explained under the hypothesis that the lensing potential is smooth
on scales smaller than one kpc. Micro-lensing by stars is a natural source of
granularity in the lens potential. The character of the expected fluctuations
due to micro-lensing depends sensitively on the relative surface densities of
micro-lenses (stars) and smoothly distributed (dark) matter. Observations of
flux ratios may therefore be used to infer the ratio of stellar to dark matter
along the line of sight -- typically at impact parameters 1.5 times the half
light radius. Several recently discovered systems have anomalies that would
seem to be explained by micro-lensing only by demanding that 70-90% of the
matter along the line of sight be smoothly distributed.


title:
Chandra Observations of a Young Embedded Magnetic B Star in the rho
  Ophiuchus Cloud

abstract:
  This paper reports on an analysis of two Chandra X-ray observations of the
young magnetic B star rho Ophiuchus S1. X-ray emission from the star was
detected in both observations. The average flux was almost the same in both,
but during each observation the flux showed significant time variations by a
factor of two on timescales of 20-40 ks. Each spectrum could be fit by either
an absorbed power-law model with a photon index of ~3 or a thin-thermal plasma
model with a temperature of ~2 keV and an extremely low metal abundance (<~0.1
solar). The spectrum of the first observation has a weak-line feature at about
6.8 keV, which might correspond to highly ionized iron Kalpha. In contrast, the
spectrum of the second observation apparently shows a weak edge absorption
component at E~4 keV. The continuum emission and log LX/Lbol ~ -6 are similar
to those of young intermediate-mass stars (Herbig Ae/Be stars), although the
presence of a strong magnetic field (inferred from the detection of non-thermal
radio emission) has drawn an analogy between rho Ophiuchus S1 and magnetic
chemically peculiar (MCP) stars. If the X-ray emission is thermal, the small
abundances that we derived might be related to the inverse first-ionization
potential (FIP) effect, though there is no significant trend as a function of
FIP from our model fits. If the emission is non-thermal, it might be produced
by high-energy electrons in the magnetosphere.


title: The Light Curve of the Unusual Supernova SN 2003dh

abstract:
  SN 2003dh, one of the most luminous supernovae ever recorded, and the one
with the highest measured velocities, accompanied gamma-ray burst 030329. Its
rapid rise to maximum and equally rapid decline pose problems for any
spherically symmetric model. We model the supernova here as a very energetic,
polar explosion that left the equatorial portions of the star almost intact.
The total progenitor mass was much greater than the mass of high-velocity
ejecta, and the total mass of 56-Ni synthesized was about 0.5 solar masses.
Such asymmetries and nickel masses are expected in the collapsar model. A
``composite two-dimensional'' model is calculated that agrees well with the
characteristics of the observed light curve. The mass of 56-Ni required for
this light curve is 0.55 solar masses and the total explosion energy, 26 x
10**51 erg.


title: Intermediate Element Abundances in Galaxy Clusters

abstract:
  We present the average abundances of the intermediate elements obtained by
performing a stacked analysis of all the galaxy clusters in the archive of the
X-ray telescope ASCA. We determine the abundances of Fe, Si, S, and Ni as a
function of cluster temperature (mass) from 1--10 keV, and place strong upper
limits on the abundances of Ca and Ar. In general, Si and Ni are overabundant
with respect to Fe, while Ar and Ca are very underabundant. The discrepancy
between the abundances of Si, S, Ar, and Ca indicate that the alpha-elements do
not behave homogeneously as a single group. We show that the abundances of the
most well-determined elements Fe, Si, and S in conjunction with recent
theoretical supernovae yields do not give a consistent solution for the
fraction of material produced by Type Ia and Type II supernovae at any
temperature or mass. The general trend is for higher temperature clusters to
have more of their metals produced in Type II supernovae than in Type Ias. The
inconsistency of our results with abundances in the Milky Way indicate that
spiral galaxies are not the dominant metal contributors to the intracluster
medium (ICM). The pattern of elemental abundances requires an additional source
of metals beyond standard SNIa and SNII enrichment. The properties of this new
source are well matched to those of Type II supernovae with very massive,
metal-poor progenitor stars. These results are consistent with a significant
fraction of the ICM metals produced by an early generation of population III
stars.


title:
Improvements in the M-T relation and mass function and the measured
  Omega_m through clusters evolution

abstract:
  In this paper, I revisit the constraints obtained by several authors
(Reichart et al. 1999; Eke et al. 1998; Henry 2000) on the estimated values of
Omega_m, n and sigma_8 in the light of recent theoretical developments: 1) new
theoretical mass functions (Sheth & Tormen 1999, Sheth, Mo & Tormen 1999, Del
Popolo 2002b); 2) a more accurate mass-temperature relation, also determined
for arbitrary Omega_m and Omega_{\Lambda} (Voit 2000, Pierpaoli et al. 2001,
Del Popolo 2002a). Firstly, using the quoted improvements, I re-derive an
expression for the X-ray Luminosity Function (XLF), similarly to Reichart et
al. (1999), and then I get some constraints to \Omega_m and n, by using the
ROSAT BCS and EMSS samples and maximum-likelihood analysis. Then I re-derive
the X-ray Temperature Function (XTF), similarly to Henry (2000) and Eke et al.
(1999), re-obtaining the constraints on Omega_m, n, sigma_8. Both in the case
of the XLF and XTF, the changes in the mass function and M-T relation produces
an increase in Omega_m of \simeq 20% and similar results in sigma_8 and n.


title:
A Far-Ultraviolet Survey of 47 Tucanae.II The Long-Period Cataclysmic
  Variable AKO 9

abstract:
  We present time-resolved, far-ultraviolet (FUV) spectroscopy and photometry
of the 1.1 day eclipsing binary system AKO 9 in the globular cluster 47
Tucanae. The FUV spectrum of AKO 9 is blue and exhibits prominent C IV and He
II emission lines. The spectrum broadly resembles that of long-period,
cataclysmic variables in the galactic field.
  Combining our time-resolved FUV data with archival optical photometry of 47
Tuc, we refine the orbital period of AKO 9 and define an accurate ephemeris for
the system. We also place constraints on several other system parameters, using
a variety of observational constraints. We find that all of the empirical
evidence is consistent with AKO 9 being a long-period dwarf nova in which mass
transfer is driven by the nuclear expansion of a sub-giant donor star. We
therefore conclude that AKO 9 is the first spectroscopically confirmed
cataclysmic variable in 47 Tuc.
  We also briefly consider AKO 9's likely formation and ultimate evolution.
Regarding the former, we find that the system was almost certainly formed
dynamically, either via tidal capture or in a 3-body encounter. Regarding the
latter, we show that AKO 9 will probably end its CV phase by becoming a
detached, double WD system or by exploding in a Type Ia supernova.


title:
The X-ray variability of the Narrow-Line Seyfert 1 galaxy IRAS
  13224-3809 from an XMM-Newton observation

abstract:
  We report on the XMM-Newton timing properties of the most X-ray variable,
radio-quiet, NLS1 IRAS 13224-3809. IRAS 13224-3809 continues to display the
extremely variable behavior that was previously observed with ROSAT and ASCA;
however, no giant, rapid flaring events are observed. We detect variations by a
factor as high as ~8 during the 64 ks observation, and the variability is
persistent throughout the light curve. Dividing the light curve into 9 minute
segments we found almost all of the segments to be variable at > 3 sigma. When
the time-averaged cross-correlation function is calculated for the 0.3-0.8 keV
band with the 3-10 keV band, the cross-correlation profile is skewed indicating
a possible smearing of the signal to longer times (soft band leading the hard).
A correlation between count rate and hardness ratio is detected in four energy
bands. In three cases the correlation is consistent with spectral hardening at
lower count rates which can be explained in terms of a partial-covering model.
The other band displays the reverse effect, showing spectral hardening at
higher count rates. We can explain this trend as a more variable power-law
component compared to the soft component. We also detect a delay between the
0.3-1.5 keV count rate and the 0.8-1.5 keV to 0.3-0.8 keV hardness ratio,
implying flux induced spectral variability. Such delays and asymmetries in the
cross correlation functions could be suggesting reprocessing of soft and hard
photons. In general, much of the timing behavior can be attributed to erratic
eclipsing behavior associated with the partial covering phenomenon, in addition
to intrinsic variability in the source. The variability behavior of IRAS
13224-3809 suggests a complicated combination of effects which we have started
to disentangle with this present analysis.


title:
Constraints on the mass spectrum of primordial black holes and
  braneworld parameters from the high-energy diffuse photon background

abstract:
  We investigate the spectral shape of a high-energy diffuse photon emitted by
evaporating primordial black holes (PBHs) in the Randall-Sundrum type II (RS2)
braneworld. In their braneworld scenario, the nature of small PBHs is
drastically modified from the ordinary four-dimensional case for the following
two reasons. (i) dropping Hawking temperature, which equivalently lengthens the
lifetime of the individual PBH due to the change of space-time topology and
(ii) the effective increase of the total amount of PBHs caused by accretion
during the earliest part of the radiation-dominated epoch, the brane
high-energy phase. From studies of the expected spectral shape and its
dependence on braneworld parameters, we obtain two qualitatively distinctive
possibilities of constraints on the braneworld PBHs from the observations of
diffuse high-energy photon background. If the efficiency of accretion in the
high-energy phase exceeds a critical value, the existence of the extra
dimension gives a more stringent upper bound on the abundance of PBHs than the
4D case and a small length scale for the extra dimension is favored. On the
contrary, in the case below the critical accretion efficiency, we find that the
constraint on the PBH abundance can be relaxed by a few orders of magnitude in
exchange for the existence of the large extra dimension; its size may be even
bounded in the region above 10^{19} times 4D Planck length scale provided the
rest mass energy density of the PBHs relative to energy density of radiation is
actually larger than 10^{-27} (4D upper bound) at their formation time. The
above analytical studies are also confirmed numerically, and an allowed region
for braneworld parameters and PBH abundance is clearly obtained.