title:
Numerical simulations of mass outflows driven from accretion disks by
  radiation and magnetic forces

abstract:
  We study the two-dimensional, time-dependent MHD of radiation-driven winds
from luminous accretion disks initially threaded by a purely axial magnetic
field. The radiation force is mediated primarily by spectral lines. We use
ideal MHD to compute the evolution of Keplerian disks, varying the magnetic
field strengths and the luminosity of the disk, the central accreting object or
both. We find that the magnetic fields very quickly start deviating from purely
axial due to the magnetorotational instability. This leads to fast growth of
the toroidal magnetic field. As a result the toroidal field dominates over the
poloidal field above the disk and the gradient of the former drives a slow and
dense disk outflow, which conserves specific angular momentum. Depending on the
strength of the magnetic field relative to the system luminosity the disk wind
can be radiation- or MHD driven. The pure radiation-driven wind consists of a
dense, slow outflow that is bounded on the polar side by a high-velocity
stream. The mass-loss rate is mostly due to the fast stream. As the magnetic
field strength increases first the slow part of the flow is affected, namely it
becomes denser and slightly faster and begins to dominate the mass-loss rate.
In very strong magnetic field or pure MHD cases, the wind consists of only a
dense, slow outflow without the presence of the distinctive fast stream so
typical to pure radiation-driven winds. Our simulations indicate that winds
launched by the magnetic fields are likely to remain dominated by the fields
downstream because of their relatively high densities.


title:
The Fundamental Plane at z=1.27: First Calibration of the Mass Scale of
  Red Galaxies at Redshifts z>1

abstract:
  We present results on the Fundamental Plane (FP) of early-type galaxies in
the cluster RDCS J0848+4453 at z=1.27. Internal velocity dispersions of three
K-selected early-type galaxies are determined from deep Keck spectra.
Structural parameters are determined from HST NICMOS images. The galaxies show
substantial offsets from the FP of the nearby Coma cluster, as expected from
passive evolution of their stellar populations. The offsets from the FP can be
expressed as offsets in M/L ratio. The M/L ratios of the two most massive
galaxies are consistent with an extrapolation of results obtained at
z=0.02-0.83. The evolution of early-type galaxies with masses >10^11 M_sun is
well described by ln M/L(B) = (-1.06 +- 0.09) z, corresponding to passive
evolution of -1.50 +- 0.13 mag at z=1.3. Ignoring selection effects, the best
fitting stellar formation redshift is z*=2.6, corresponding to a luminosity
weighted age at the epoch of observation of ~2 Gyr. The M/L ratios of these two
galaxies are also in excellent agreement with predictions from models that
include progenitor bias. The third galaxy is a factor ~10 less massive than the
other two, shows strong Balmer absorption lines in its spectrum, and is offset
from the Coma Fundamental Plane by 2.9 mag in rest-frame B. Despite their large
range in M/L ratios, all three galaxies fall in the ``Extremely Red Object''
(ERO) class with I-H>3 and R-K>5, and our results show that it is hazardous to
use simple models for converting luminosity to mass for these objects.
Measurements of M/L ratios at high redshift can be considered first steps to
empirically disentangle luminosity and mass evolution at the high mass end of
the galaxy population, lifting an important degeneracy in the interpretation of
evolution of the luminosity function. [SHORTENED]


title:
Possible arcminute-separation gravitational lensed QSOs in the 2dF QSO
  survey

abstract:
  We report the possible discovery of multiple gravitationally-lensed images of
QSOs with angular separations on arcminute scales. The QSOs were selected from
the completed 2dF QSO survey as having redshifts and optical colours which are
statistically consistent. In this paper we present higher-quality optical
spectra of the candidates and discuss the likelihood of their genuinely being
systems lensed by massive clusters of galaxies. From a comparison of the
spectra it appears that up to six pairs of QSOs may be lensed multiple images,
although the true number may be less than that and further observations should
be undertaken to amass more evidence and to detect the lensing clusters. Two of
the candidates may be associated with low redshift clusters of galaxies.


title:
A Submillimeter and Radio Survey of Gamma-Ray Burst Host Galaxies: A
  Glimpse into the Future of Star Formation Studies

abstract:
  We present the first comprehensive search for submillimeter and radio
emission from the host galaxies of twenty well-localized gamma-ray bursts
(GRBs). With the exception of a single source, all observations were undertaken
months to years after the GRB explosions to ensure negligible contamination
from the afterglows. We detect the host galaxy of GRB 000418 in both the sub-mm
and radio, and the host galaxy of GRB 000210 only in the sub-mm. These
observations, in conjunction with the previous detections of the host galaxies
of GRB 980703 and GRB 010222, indicate that about 20% of GRB host galaxies are
ultra-luminous and have star formation rates of about 500 M_sun/yr. As an
ensemble, the non-detected hosts have a star formation rate of about 100
M_sun/yr (5-sigma) based on their radio emission. The detected and ensemble
star formation rates exceed the optical values by an order of magnitude,
indicating significant dust obscuration. In the same vein, the ratio of
bolometric dust luminosity to UV luminosity for the hosts detected in the
sub-mm and radio ranges from 20-800, and follows the known trend of increasing
obscuration with increasing bolometric luminosity. We also show that, both as a
sample and individually, the GRB host galaxies have bluer R-K colors as
compared with galaxies selected in the sub-mm in the same redshift range. This
possibly indicates that the stellar populations in the GRB hosts are on average
younger, supporting the massive stellar progenitor scenario for GRBs, but it is
also possible that GRB hosts are on average less dusty.


title: Density gradients and internal dust in the Orion nebula

abstract:
  The ionization structure of the Orion nebula can be described as a skin-like
ionization structure on the surface of a dense cloud. We propose that a steep
density stratification, increasing as a powerlaw ($n \propto x^{-2}$) function
of distance x from the ionization front, exhibits properties which agree with
our long-slit spectrum of the Orion nebula. For instance, there exist a unicity
relation between both the Hbeta surface brightness or the ionization front
[SII] density, and the scale L of the powerlaw, where L is the distance between
the ionization front and the onset of the density near the exciting star.
Internal dust is required to obtain a simultaneous acceptable fit of both the
[SII] density and then Hbeta suface brightness observations. Nebular models
containing small dust grains provide a better fit than large grains. The line
ratio gradients observed along the slit are qualitatively reproduced by our
density stratified models assuming a stellar temperature of 38000 K.
Collisional deexcitation appears to be responsible for half of the gradient
observed in the [NII] 5755/6583 temperature sensitive ratio. We propose that
the empirical relationship found by Wen & O'dell between density and stellar
distance may possibly be caused by a power-law density stratification.


title:
High-speed energy-resolved STJ photometry of the eclipsing dwarf nova IY
  UMa

abstract:
  We present high time-resolution photometry of the dwarf nova IY UMa using the
S-Cam2 super-conducting tunnel junction device attached to the 4.2m William
Herschel Telescope on La Palma. Exploiting the well-defined white dwarf and hot
spot eclipse features, we derive an updated orbital ephemeris for IY UMa and an
orbital period of 0.07390897(5) days. A white dwarf ingress/egress duration of
31 +/- 2s along with the contact phases of the bright spot gives M_1=0.79 +/-
0.04 M_sun and M_2=0.10 +/- 0.01 Msun, corresponding to a mass ratio of q=0.125
+/- 0.008. The white dwarf eclipse width of 0.0637 then implies i=86.0 +/- 1
degrees. A curious rise with a duration of 30 +/- 2s is observed in the orbital
lightcurves during all three observed eclipses. It occurs between the end of
white dwarf ingress and hot spot ingress and is blue in colour. We suggest that
the source of this light lies in the buried part of the gas stream, resulting
in a compact, hot impact cavity.


title: On the structures in the afterglow peak emission of gamma ray bursts

abstract:
  Using GRB 991216 as a prototype, it is shown that the intensity substructures
observed in what is generally called the "prompt emission" in gamma ray bursts
(GRBs) do originate in the collision between the accelerated baryonic matter
(ABM) pulse with inhomogeneities in the interstellar medium (ISM). The initial
phase of such process occurs at a Lorentz factor $\gamma\sim 310$. The crossing
of ISM inhomogeneities of sizes $\Delta R\sim 10^{15}$ cm occurs in a detector
arrival time interval of $\sim 0.4$ s implying an apparent superluminal
behavior of $\sim 10^5c$. The long lasting debate between the validity of the
external shock model vs. the internal shock model for GRBs is solved in favor
of the first.


title: The GEO600 Gravitational Wave Detector -- Pulsar Prospects

abstract:
  The GEO600 laser-interferometric gravitational wave detector near Hannover,
Germany, is one of six such interferometers now close to operation worldwide.
The UK/German GEO collaboration uses advanced technologies, including
monolithic silica suspensions and signal recycling, to deliver a sensitivity
comparable with much larger detectors in their initial configurations. Here we
review the design and performance of GEO600 and consider the prospects for a
direct detection of continuous gravitational waves from spinning neutron stars.


title: Multiwavelength Time Series Data of the LMC Cluster Reticulum

abstract:
  We present accurate multiwavelength UBVI time series data of the LMC cluster
Reticulum. Data cover a time interval of ~ 6 yr and have been collected with
SUSI1/2 and SOFI at NTT/ESO. For each band we collected approximately 30
short/long exposures and the total exposure times range from roughly 3500 (U,
B), 6000s (V) to 8300s (I). The observing strategy and data reduction
(DAOPHOTII/ALLFRAME) allowed us to reach a photometry accuracy of 0.02
magnitude from the tip of the Red Giant Branch well below the Turn-Off region.
Even though this cluster presents a very low central density, we found a
sizable sample of Blue Stragglers (BSs). We also selected stars with a
variability index larger than 2, and interestingly enough we detected together
with the RR Lyrae stars a large sample of variable stars around and below the
TO region. Preliminary analysis on the luminosity variation indicate that these
objects might be binary stars.


title: An XMM-Newton Study of Hard X-ray Sources

abstract:
  We briefly report on an on-going spectroscopic study of hard X-ray sources
selected serendipitously in 12 XMM-Newton fields. Results for the analysis of
the 41 sources from the first seven EPIC observations have been discussed in a
previous paper (Piconcelli et al. 2002, Paper I) where we found an absolute
fraction of X-ray absorbed sources (~30%) lower than expected (~50%) by the
predictions of popular CXB synthesis models at F(2-10)~5x10**(-14) erg cm**-2
s**-1. We present here the preliminary results concerning the whole sample
including five new deeper XMM-Newton measurements increasing the sample to 90
sources. Even if still on-going, the present study appears to confirm and
extend down to F(2-10)~10**(-14) erg cm**-2 s**-1 the above mismatch between
observational data and theoretical expectations regarding the fraction of
absorbed sources. Furthermore the sample average spectral index of 1.5-1.6 is
steeper than the CXB slope indicating that the majority of obscured sources
making the bulk of the CXB resides at even lower hard X-ray fluxes.


title: The Structure of Stellar Coronae in Active Binary Systems

abstract:
  A survey of 28 stars using EUV spectra has been conducted to establish the
structure of stellar coronae in active binary systems from the EMD, electron
densities, and scale sizes. Observations obtained by the EUVE during 9 years of
operation are included for the stars in the sample. EUVE data allow a
continuous EMD to be constructed in the range log T~5.6-7.4, using iron
emission lines. These data are complemented with IUE observations to model the
lower temperature range. Inspection of the EMD shows an outstanding narrow
enhancement, or ``bump'' peaking around log T~6.9 in 25 of the stars, defining
a fundamental coronal structure. The emission measure per unit stellar area
decreases with increasing orbital (or photometric) periods of the target stars;
stars in binaries generally have more material at coronal temperatures than
slowly rotating single stars. High electron densities (Ne>10^12 cm^-3) are
derived at ~10 MK for some targets, implying small emitting volumes. The
observations suggest the magnetic stellar coronae of these stars are consistent
with two basic classes of magnetic loops: solar-like loops with maximum
temperature around log T~6.3 and lower electron densities (Ne>10^9-10.5), and
hotter loops peaking around log T~6.9 with higher electron densities
(Ne>10^12). For the most active stars, material exists at much higher
temperatures (log T>6.9) as well. However, current ab initio stellar loop
models cannot reproduce such a configuration. Analysis of the light curves of
these systems reveals signatures of rotation of coronal material, as well as
apparent seasonal changes in the activity levels.


title: The Be star content of young open clusters

abstract:
  We present a photometric survey aimed to characterize the Be star population
of young open clusters. It is found that in these clusters early-type Be stars
are more frequent than in the galactic field, and late-type Be stars are scarce
or inexistent. We interpret this result as evidence for an evolutionary
enhancement of the Be phenomenon towards the end of the main sequence lifetime.


title: Absorption Systems in the Spectrum of GRB 021004

abstract:
  We report on a 3600 s spectrum of GRB 021004 obtained with the Nordic Optical
Telecope on La Palma 10.71 hours after the burst. We identify absorption lines
from five systems at redshifts 1.3806, 1.6039, 2.2983, 2.3230, and 2.3292. In
addition we find an emission line which, if due to Ly-alpha from the host
galaxy, gives a redshift of 2.3351. The nearest absorber is blueshifted by 530
km/s with respect to this line, consistent with shifts seen in Damped Ly-alpha
and Lyman-Break galaxies at similar redshifts. The emission line flux is
2.46+-0.50 x 10^-16 erg/s/cm^2. Some of the absorption systems are
"line-locked", an effect often seen in QSO absorption systems believed to
originate close to the QSO central engine.


title: Quark Matter in Neutron Star Mergers

abstract:
  Binary neutron star mergers are expected to be one of the most promising
source of gravitational waves (GW) for the network of laser interferometric and
bar detectors becoming operational in the next few years. The merger wave
signal is expected to be sensitive to the interior structure of the neutron
star (NS). The structure of high density phases of matter is under current
experimental investigation in heavy-ion collisions. We investigate the
dependence of the merger process and its GW signal on the presence of quarks in
these phases by performing numerical simulations, where the smoothed particle
hydrodynamics (SPH) method and the conformally flat approximation for the
3-geometry in general relativistic gravity are implemented.


title:
Dynamical Evolution of Gamma-Ray Burst Remnants with Evolving Radiative
  Efficiency

abstract:
  In previous works, a generic dynamical model has been suggested by Huang et
al., which is shown to be correct for both adiabatic and radiative blastwaves,
and in both ultra-relativistic and non-relativistic phases. In deriving their
equations, Huang et al. have assumed that the radiative efficiency of the
fireball is constant. They then applied their model directly to realistic cases
where the radiative efficiency evolves with time. In this paper, we abandon the
above assumption and re-derive a more accurate dynamical equation for gamma-ray
burst remnants. Numerical results show that Huang et al.'s model is accurate
enough in general cases.


title: [C II] emission and star formation in late-type galaxies. II A model

abstract:
  We study the relationship between gas cooling via the [C II] (158 micron)
line emission and dust cooling via the far-IR continuum emission on the global
scale of a galaxy in normal (i.e. non-AGN dominated and non-starburst)
late-type systems. It is known that the luminosity ratio of total gas and dust
cooling, L(C II)/L(FIR), shows a non-linear behaviour with the equivalent width
of the Halpha line emission, the ratio decreasing in galaxies of lower massive
star-formation activity. This result holds despite the fact that known
individual Galactic and extragalactic sources of the [C II] line emission show
different [C II] line-to-far-IR continuum emission ratios. This non-linear
behaviour is reproduced by a simple quantitative model of gas and dust heating
from different stellar populations, assuming that the photoelectric effect on
dust, induced by far-UV photons, is the dominant mechanism of gas heating in
the general diffuse interstellar medium of the galaxies under investigation.
According to the model, the global L(C II)/L(FIR) provides a direct measure of
the fractional amount of non-ionizing UV light in the interstellar radiation
field and not of the efficiency of the photoelectric heating. The model also
defines a method to constrain the stellar initial mass function from
measurements of L(C II) and L(FIR). A sample of 20 Virgo cluster galaxies
observed in the [C II] line with the LWS on board ISO is used to illustrate the
model. The limited statistics and the necessary assumptions behind the
determination of the global [C II] luminosities from the spatially limited data
do not allow us to establish definitive conclusions but data-sets available in
the future will allow tests of both the reliability of the assumptions of our
model and the statistical significance of our results.


title:
Can Supermassive Black Holes alter Cold Dark Matter cusps through
  accretion?

abstract:
  We present some simple models to determine whether or not the accretion of
cold dark matter by supermassive black holes is astrophysically important.
Contrary to some claims in the literature, we show that supermassive black
holes cannot significantly alter a power law density cusp via accretion,
whether during mergers or in the steady state.


title: Optical Continuum Sources in Gravitationally Lensed Quasars

abstract:
  We review some techniques to study the nature and size of the optical
continuum sources in multiple QSOs. We focus on the source originating the
events with several months timescale (the rapid variability source) as well as
the source that is responsible for the non-variable background component (the
background source). The techniques are used to study both the rapid variability
source in Q0957+561 and the main (compact) background source in Q2237+0305.


title:
Age and Metallicity Distribution of the Galactic Bulge from Extensive
  Optical and Near-IR Stellar Photometry

abstract:
  We present a new determination of the metallicity distribution, age, and
luminosity function of the Galactic bulge stellar population. By combining
near-IR data from the 2MASS survey, from the SOFI imager at ESO NTT and the
NICMOS camera on board HST we were able to construct color-magnitude diagrams
(CMD) and luminosity functions (LF) with large statistics and small photometric
errors from the Asymptotic Giant Branch (AGB) and Red Giant Branch (RGB) tip
down to $\sim 0.15 M_\odot$. This is the most extended and complete LF so far
obtained for the galactic bulge. Similar near-IR data for a disk control field
were used to decontaminate the bulge CMDs from foreground disk stars, and hence
to set stronger constraint on the bulge age, which we found to be as large as
that of Galactic globular clusters, or $\gsim 10$ Gyr. No trace is found for
any younger stellar population. Synthetic CMDs have been constructed to
simulate the effect of photometric errors, blending, differential reddening,
metallicity dispersion and depth effect in the comparison with the
observational data. By combining the near-IR data with optical ones, from the
Wide Field Imager at the ESO/MPG 2.2m telescope, a disk-decontaminated
$(M_K,V-K)$ CMD has been constructed and used to derive the bulge metallicity
distribution, by comparison with empirical RGB templates. The bulge metallicity
is found to peak at near solar value, with a sharp cutoff just above solar, and
a tail towards lower metallicity that does not appreciably extend below
[M/H]$\sim-1.5$.


title: VLBI Techniques in Pulsar Astronomy

abstract:
  Very long baseline interferometry (VLBI) provides the resolution needed to
make precision measurements of a pulsar's parallax and proper motion. In making
these measurements, the astronomer is faced with difficult calibration problems
and a paucity of strong point-like calibrators that ultimately limit the
accuracy of parallax measurements of even the brightest pulsars. A new
technique to calibrate away the effects of the ionosphere, the dominant source
of phase error at frequencies below 5 GHz, has led to the new measurements of
nine pulsar parallaxes to 100 microarcsecond or better precision.


title:
High Resolution X-ray Spectroscopic Constraints on Cooling-Flow Models
  for Clusters of Galaxies

abstract:
  We present high resolution X-ray spectra of 14 putative cooling-flow clusters
of galaxies obtained with the Reflection Grating Spectrometer on XMM-Newton.
The clusters in the sample span a large range of temperatures and mass
deposition rates. Various of these spectra exhibit line emission from O VIII,
Ne X, Mg XII & XI, Al XIII & XII, Si XIV & XIII, N VII, and C VI as well as all
Fe L ions. The spectra exhibit strong emission from cool plasma at just below
the ambient temperature, $T_0$, down to $T_0/2$, but also exhibit a severe
deficit of emission, relative to the predictions of the isobaric cooling-flow
model at lower temperatures ($<$ $T_0/3$). In addition, the best-resolved
spectra show emission throughout the entire X-ray temperature range, but
increasingly less emission at lower temperatures than the cooling-flow model
would predict. These results are difficult to reconcile with simple
prescriptions for distorting the emission measure distribution, e.g. by
including additional heating or rapid cooling terms. We enumerate some
theoretical difficulties in understanding the soft X-ray spectra of
cooling-flows independent of the classic problem of the failure to detect the
cooling-flow sink. Empirically, the differential luminosity distribution is
consistent with being proportional to the temperature to the power of $\approx$
1 to 2, instead of being independent of the temperature, as expected in the
standard multi-phase model. The primary differences in the observed low
temperature spectra are ascribed to differences in the ambient temperature.


title: Variable Stars in M31's Globular Clusters

abstract: This paper has been withdrawn.


title: Monte Carlo Methods for X-ray Dispersive Spectrometers

abstract:
  We discuss multivariate Monte Carlo methods appropriate for X-ray dispersive
spectrometers. Dispersive spectrometers have many advantages for high
resolution spectroscopy in the X-ray band. Analysis of data from these
instruments is complicated by the fact that the instrument response functions
are multi-dimensional and relatively few X-ray photons are detected from
astrophysical sources. Monte Carlo methods are the natural solution to these
challenges, but techniques for their use are not well developed. We describe a
number of methods to produce a highly efficient and flexible multivariate Monte
Carlo. These techniques include multi-dimensional response interpolation and
multi-dimensional event comparison. We discuss how these methods have been
extensively used in the XMM-Newton Reflection Grating Spectrometer in-flight
calibration program. We also show several examples of a Monte Carlo applied to
observations of clusters of galaxies and elliptical galaxies with the
XMM-Newton observatory.


title:
High Resolution X-Ray Spectroscopic Constraints on Cooling Flow Models
  of Clusters of Galaxies and Gaseous Haloes Around Elliptical Galaxies

abstract:
  In many clusters of galaxies, the cooling time at the core of the
intracluster medium is much less than the age of the system, suggesting that
the the gas should continually lose energy by radiation. Simple thermodynamic
arguments then require that the expected "cooling flow" should exhibit a
specific spectroscopic signature, characterized by a differential emission
measure distribution that is inversely proportional to the cooling function of
the plasma. That prediction can be quantitatively tested for the first time by
the Reflection Grating Spectrometer (RGS) experiment on XMM-Newton, which
provides high resolution X-ray spectra, even for moderately extended sources
like clusters. We present RGS data on 14 separate cooling flow clusters,
sampling a very wide range in mass deposition rate. Surprisingly, in all cases
we find a systematic deficit of low temperature emission relative to the
predictions of the cooling flow models. However, we do see evidence for cooling
flow gas at temperatures just below the cluster background temperature, $T_0$,
roughly down to $T_0/2$. These results are difficult to reconcile with most of
the possible explanations for the cooling flow problem that have been proposed
to date. We also present RGS data on the massive elliptical galaxy NGC 4636. In
this case, we detect evidence for resonance emission line scattering of high
oscillator strength Fe L-shell emission lines within the gaseous halo of the
galaxy. The detection of that effect leads to very tight constraints on
physical conditions within the halo. However, here again, the expected
signature of a cooling flow is not detected, perhaps suggesting some
fundamental uncertainty in our understanding of radiative cooling in low
density cosmic plasmas.


title:
Chandra Detection of Local OVII He-alpha Absorption Along the Sight Line
  Toward 3C 273

abstract:
  With the Chandra X-ray Telescope we have detected a zero-redshift OVII
He-alpha absorption line along the sight line toward 3C 273. This line
detection is highly significant, with a signal-to-noise ratio (S/N) of 6.4. We
explore two models, which associate this line with (1) the intragroup gas in
the Local Group, and (2) the hot halo gas in the vicinity of our Milky Way. In
the first model, we find that for a standard beta-model of the gas distribution
in the Local Group, the temperature is constrained to 2.3e5 < T < 1.2e6 K and
the baryon overdensity is delta_b ~ 100; both results are consistent with the
properties of the so-called warm-hot intergalactic medium (WHIM) predicted by
cosmological simulations. We also find the core radius of the gas distribution
should be > 100 kpc. In the second model we discuss several possible Galactic
origins for the absorption, and we comment on the possibility that the OVII is
associated with the OVI absorption observed in this direction by the Far
Ultraviolet Spectroscopic Explorer (FUSE). We find that there is a strong
indication that collisional ionization is the dominant ionization source for
the observed absorption.


title: Surveys of Galaxy Clusters with the Sunyaev Zel'dovich Effect

abstract:
  We have created mock Sunyaev-Zel'dovich effect (SZE) surveys of galaxy
clusters using high resolution N-body simulations. To the pure surveys we add
`noise' contributions appropriate to instrument and primary CMB anisotropies.
Applying various cluster finding strategies to these mock surveys we generate
catalogues which can be compared to the known positions and masses of the
clusters in the simulations. We thus show that the completeness and efficiency
that can be achieved depend strongly on the frequency coverage, noise and beam
characteristics of the instruments, as well as on the candidate threshold. We
study the effects of matched filtering techniques on completeness, and bias. We
suggest a gentler filtering method than matched filtering in single frequency
analyses. We summarize the complications that arise when analyzing the SZE
signal at a single frequency, and assess the limitations of such an analysis.
Our results suggest that some sophistication is required when searching for
`clusters' within an SZE map.


title: The Remarkably Featureless High Resolution X-ray Spectrum of Mrk 478

abstract:
  An observation of Mrk 478 using the Chandra Low Energy Transmission Grating
Spectrometer is presented. The source exhibited 30-40% flux variations on
timescales of order 10000 s together with a slow decline in the spectral
softness over the full 80 ks observation. The 0.15--3.0 keV spectrum is well
fitted by a single power law with photon index of Gamma = 2.91 +/- 0.03.
Combined with high energy data from BeppoSAX, the spectrum from 0.15 to 10 keV
is well fit as the sum of two power laws with Gamma = 3.03 +/- 0.04, which
dominates below 2 keV and 1.4 +/- 0.2, which dominates above 2 keV (quoting 90%
confidence uncertainties). No significant emission or absorption features are
detected in the high resolution spectrum, supporting our previous findings
using the Extreme Ultraviolet Explorer but contradicting the claims of emission
lines by Hwang & Bowyer (1997). There is no evidence of a warm absorber, as
found in the high resolution spectra of many Sy 1 galaxies including others
classified as narrow line Sy 1 galaxies such as Mrk 478. We suggest that the
X-ray continuum may result from Comptonization of disk thermal emission in a
hot corona through a range of optical depths.


title: On the magnetic fields and particle acceleration in Cas A

abstract:
  We investigate the non-thermal X-ray emission from Cas A. For the hard X-ray
continuum we test the model proposed by Laming, which invokes bremsstrahlung
from electrons accelerated by lower hybrid plasma waves. The justification for
this model comes from our determination of a lower limit to the average
magnetic field of B > 0.5 mG, which suggest that most of the electron
populations are too much affected by synchrotron losses to produce X-ray
synchrotron emission. An exception is the X-ray emission from the rim
surrounding Cas A, seen in Chandra continuum images. The width of this rim of
1.5" to 4", can be used to infer the magnetic field near the shock front, for
which we estimate B = 0.08 - 0.16 mG, and electron energies of about 57 - 40
TeV. This is lower than the average magnetic field, but higher than what may be
expected from shocked interstellar medium, suggesting a high pre-shock magnetic
field, or rapid, post shock, field amplification. Combining the two magnetic
field measurements we have constructed a simple two zone model. Most of the
radio emission comes from inside Cas A, where the magnetic field is strong,
whereas the inverse Compton emission comes from near the shock front. Only for
our lower limit on the magnetic field strength near the shock front is it
possible to explain the recent detection of TeV emission by HEGRA with inverse
Compton, for which, in addition, we have to assume a rather high far infrared
photon density that should be twice as high as our best estimate of roughly 70
cm^{-3}. Pion decay is therefore likely to be the dominant emission from Cas A
at TeV energies.


title: Global Alfven Wave Heating of the Magnetosphere of Young Stars

abstract:
  Excitation of a Global Alfven wave (GAW) is proposed as a viable mechanism to
explain plasma heating in the magnetosphere of young stars. The wave and basic
plasma parameters are compatible with the requirement that the dissipation
length of GAWs be comparable to the distance between the shocked region at the
star's surface and the truncation region in the accretion disk. A two-fluid
magnetohydrodynamic plasma model is used in the analysis. A current carrying
filament along magnetic field lines acts as a waveguide for the GAW. The
current in the filament is driven by plasma waves along the magnetic field
lines and/or by plasma crossing magnetic field lines in the truncated region of
the disk of the accreting plasma. The conversion of a small fraction of the
kinetic energy into GAW energy is sufficient to heat the plasma filament to
observed temperatures.


title: Electromagnetic Outflows and GRBs

abstract:
  We study the dynamics of relativistic electromagnetic explosions as a
possible mechanism for the production of Gamma-Ray Bursts. We propose that a
rotating relativistic stellar-mass progenitor loses much of its spin energy in
the form of an electromagnetically-dominated outflow.
  After the flow becomes optically thin, it forms a relativistically expanding,
non-spherically symmetric magnetic bubble - a ''cold fireball''. We analyze the
structure and dynamics of such a cavity in the force-free approximation. During
relativistic expansion, most of the magnetic energy in the bubble is
concentrated in a thin shell near its surface (contact discontinuity). We
suggest that either the polar current or the shell currents become unstable to
electromagnetic instabilities at a radius $\sim10^{16}$ cm. This leads to
acceleration of pairs and causes the $\gamma$-ray emission. At a radius
$\sim10^{17}$ cm, the momentum contained in the electromagnetic shell will have
been largely transferred to the surrounding blast wave propagating into the
circumstellar medium. Particles accelerated at the fluid shock may combine with
electromagnetic field from the electromagnetic shell to produce the afterglow
emission.


title: HII regions in symbiotic binaries and their radio emission

abstract:
  The slow and dense wind from a symbiotic red giant can be significantly
deflected toward the orbital plane by the gravitational pull of the companion
star. In such an environment, the ionizing radiation from the companion creates
a highly asymmetric HII region. We present three-dimensional models of HII
regions in symbiotic S-type systems, for which we calculate radio maps and
radio spectra. We show that the standard assumption of spherically symmetric RG
wind results in wrong shapes, sizes and spectra of ionized regions, which in
turn affects the observational estimates of orbital separation and mass loss
rate. A sample of radio maps and radio spectra of our models is presented and
the results are discussed in relation to observational data.


title: BATSE Soft Gamma-Ray Observations of GROJ0422+32

abstract:
  We report results of a comprehensive study of the soft gamma-ray (30 keV to
1.7 MeV) emission of GROJ0422+32 during its first known outburst in 1992. These
results were derived from the BATSE earth-occultation database with the JPL
data analysis package, EBOP (Enhanced BATSE Occultation Package). Results
presented here focus primarily on the long-term temporal and spectral
variability of the source emission associated with the outburst. The light
curves with 1-day resolution in six broad energy-bands show the high-energy
flux (>200 keV) led the low-energy flux (<200 keV) by ~5 days in reaching the
primary peak, but lagged the latter by ~7 days in starting the declining phase.
We confirm the "secondary maximum" of the low-energy (<200 keV) flux at TJD
8970-8981, ~120 days after the first maximum. Our data show that the "secondary
maximum" was also prominent in the 200-300 keV band, but became less pronounced
at higher energies. During this 200-day period, the spectrum evolved from a
power-law with photon index of 1.75 on TJD 8839, to a shape that can be
described by a Comptonized model or an exponential power law below 300 keV,
with a variable power-law tail above 300 keV. The spectrum remained roughly in
this two-component shape until ~9 November (TJD 8935) and then returned to the
initial power-law shape with an index of ~2 until the end of the period. The
correlation of the two spectral shapes with the high and low luminosities of
the soft gamma-ray emission is strongly reminiscent of that seen in Cygnus X-1.
We interpret these results in terms of the Advection Dominated Accretion Flow
(ADAF) model with possibly a "jet-like" region that persistently produced the
non-thermal power-law gamma rays observed throughout the event.


title:
Photometric study of new southern SU UMa-type dwarf novae and
  candidates: V877 Ara, KK Tel and PU CMa

abstract:
  We photometrically observed three dwarf novae V877 Ara, KK Tel and PU CMa. We
discovered undisputed presence of superhumps in V877 Ara and KK Tel, with mean
periods of 0.08411(2) d and 0.08808(3) d, respectively. Both V877 Ara and KK
Tel are confirmed to belong to long-period SU UMa-type dwarf novae. In V877
Ara, we found a large decrease of the superhump period (dot(P)/P = -14.5 +/-
2.1 x 10^(-5)). There is evidence that the period of KK Tel decreased at a
similar or a more exceptional rate. Coupled with the past studies of superhump
period changes, these findings suggest that a previously neglected diversity of
phenomena is present in long-period SU UMa-type dwarf novae. The present
discovery of a diversity in long-period SU UMa-type systems would become an
additional step toward a full understanding the dwarf nova phenomenon. PU CMa
is shown to be an excellent candidate for an SU UMa-type dwarf nova. We
examined the outburst properties of these dwarf novae, and derived
characteristic outburst recurrence times. Combined with the recently published
measurement of the orbital period of PU CMa, we propose that PU CMa is the
first object filling the gap between the extreme WZ Sge-type and ER UMa-type
stars.


title:
Target Selection for SETI: 1. A Catalog of Nearby Habitable Stellar
  Systems

abstract:
  In preparation for the advent of the Allen Telescope Array, the SETI
Institute has the need to greatly expand its former list of ~2000 targets
compiled for Project Phoenix, a search for extraterrestrial technological
signals. In this paper we present a catalog of stellar systems that are
potentially habitable to complex life forms (including intelligent life), which
comprises the largest portion of the new SETI target list. The Catalog of
Nearby Habitable Systems (HabCat) was created from the Hipparcos Catalogue by
examining the information on distances, stellar variability, multiplicity,
kinematics and spectral classification for the 118,218 stars contained therein.
We also make use of information from several other catalogs containing data for
Hipparcos stars on X-ray luminosity, CaII H&K activity, rotation, spectral
types, kinematics, metallicity, and Stroemgren photometry. Combined with
theoretical studies on habitable zones, evolutionary tracks and third body
orbital stability, these data were used to remove unsuitable stars from HabCat,
leaving a residue of stars that, to the best of our current knowledge, are
potentially habitable hosts for complex life. While this Catalog will no doubt
need to be modified as we learn more about individual objects, the present
analysis results in 17,129 Hipparcos "habstars" near the Sun (75% within 140
pc), ~2200 of which are known or suspected to be members of binary or triple
star systems.


title: Evolutionary Synthesis Models for Galaxy Transformation in Clusters

abstract:
  The galaxy population in rich local galaxy clusters shows a ratio of one
quarter elliptical galaxies, two quarters S0 galaxies, and one quarter spiral
galaxies. Observations of clusters at redshift 0.5 show a perspicuously
different ratio, the dominant galaxy type are spiral galaxies with a fraction
of two quarters while the number of S0 galaxies decreases to a fraction of one
quarter (Dressler et al.1997). This shows an evolution of the galaxy population
in clusters since redshift0.5 and it has been suspected that galaxy
transformation processes during the infall into a cluster are responsible for
this change. These could be merging, starburst or ram-pressure stripping. We
use our evolutionary synthesis models to describe various possible effects of
those interactions on the star formation of spiral galaxies infalling into
clusters. We study the effects of starbursts of various strengths as well as of
the truncation of star formation at various epochs on the color and luminosity
evolution of model galaxies of various spectral types. As a first application
we present the comparison of our models with observed properties of the local
S0 galaxy population to constrain possible S0 formation mechanisms in clusters.
Application to other types of galaxies is planned for the future.


title:
Thermodynamical description of a family of partially relaxed stellar
  systems

abstract:
  We examine the thermodynamical properties of a family of partially relaxed,
anisotropic stellar systems, derived earlier from the Boltzmann entropy under
the assumption that a third quantity Q is conserved in addition to the total
energy and the total number of stars. We now show that the family of models
conforms to the paradigm of the gravothermal catastrophe, which is expected to
occur (in the presence of adequate energy transport mechanisms) when the
one-parameter equilibrium sequence attains sufficiently high values of the
concentration parameter; these are the values for which the models are well
fitted by the R^(1/4) law. In the intermediate concentration regime the models
belonging to the sequence exhibit significant deviations from the R^(1/4) law.
Curiously, in the low-concentration regime, the global thermodynamical
temperature associated with the models becomes negative when the models become
too anisotropic so that they are unstable against the radial orbit instability;
this latter behavior, while offering a new clue to the physical interpretation
of the radial orbit instability, is at variance with respect to the
low-concentration limit of the classical case of the isotropic, isothermal
sphere investigated by Bonnor (1956) and Lynden-Bell & Wood (1968).


title: Real space statistical properties of standard cosmological models

abstract:
  After reviewing some basic relevant properties of stationary stochastic
processes (SSP), we discuss the properties of the so-called Harrison-Zeldovich
like spectra of mass density perturbations. These correlations are a
fundamental feature of all current standard cosmological models. Examining them
in real space we note they imply a "sub-poissonian" normalised variance in
spheres $\sigma_M^2(R) \sim R^{-4} \ln R$. In particular this latter behaviour
is at the limit of the most rapid decay ($\sim R^{-4}$) of this quantity
possible for any stochastic distribution (continuous or discrete). In a simple
classification of all SSP into three categories, we highlight with the name
``super-homogeneous'' the properties of the class to which models like this,
with $P(0)=0$, belong. In statistical physics language they are well described
as lattice or glass-like. We illustrate their properties through two simple
examples: (i) the ``shuffled'' lattice and the One Component Plasma at thermal
equilibrium.


title: The clustering of sub-mJy radio sources in The Bootes Deep Field

abstract:
  We measure the angular clustering of ~2000 radio sources in The Bootes Deep
Field, covering 5.3 deg^2 down to S(1.4 GHz)=0.2 mJy. With reference to work by
Blake & Wall, we show that the size distribution of multi-component radio
galaxies dominates the overall clustering signal, and that its amplitude
extrapolates smoothly from their measurements above 5 mJy. The upper limits on
any true galaxy-galaxy clustering are consistent with the clustering of the
sub-mJy radio-loud AGN being effectively diluted by the more weakly-clustered
IRAS-type starburst galaxies. Source count models imply that the survey
contains around 400 of the latter galaxies above 0.2 mJy out to z ~ 1 to 2.
Measurement of their clustering must await their identification via the optical
and infrared data due on this field.


title:
Interstellar extinction in the open clusters towards galactic longitude
  around 130 degrees

abstract:
  In this paper we present a detailed study of the intra-cluster reddening
material in the young open clusters located around $l \sim 130^o$ using
colour-excess diagrams and two-colour diagrams. The study supports the
universality of the extinction curves for $\lambda \geq \lambda_J$, whereas for
shorter wavelengths the curve depends upon the value of the $R_{cluster}$
(total-to-selective absorption in the cluster region). The value of
$R_{cluster}$ in the case of NGC 654, NGC 869 and NGC 884 is found to be
normal, whereas the value of $R_{cluster}$ in the cluster regions NGC 1502 and
IC 1805 indicates an anomalous reddening law in these regions. It is also found
that the extinction process in the $U$ band in the case of NGC 663 seems to be
less efficient, whereas in the case of NGC 869 the process is more efficient.


title: Galactic X-ray Survey

abstract:
  We review highlights of the results obtained from recent Galactic X-ray
survey observations, in particular ASCA Galactic center and plane survey and
our Chandra deep survey on the (l,b)=(28.5,0) region. Strong hard X-ray diffuse
components are observed from Galactic ridge, center and bulge, and they have
both thermal and non-thermal spectral components. Dozens of discrete and
extended sources have been discovered on the Galactic plane, which also
indicate thermal and/or non-thermal X-ray energy spectra. They are often
associated with radio sources and are considered to be SNR candidates. Most of
the hard X-ray point sources in the outer part of the Galactic plane are
considered to be background AGNs, while fraction of the Galactic hard X-ray
sources (such as quiescent dwarf novae) increases toward the Galactic center.
Most of the soft X-ray sources on the Galactic plane are presumably nearby
active stars.


title:
Near-Infrared Identification of the Dimmest X-ray Sources on the
  Galactic Plane with the ESO/NTT SOFI Camera

abstract:
  We have carried out a deep X-ray observation on a typical Galactic plane
region with the Chandra ACIS-I instrument with unprecedented sensitivity and
spatial resolution, and detected 274 unidentified X-ray point sources in the
\~500 arcmin2 region. In order to identify these new X-ray sources, we have
carried out a near infrared follow-up observation using ESO/NTT infrared camera
on 2002/7/28 and 2002/7/29. Initial results are briefly reported.


title: ASCA Slew Survey

abstract:
  We are systematically analyzing ASCA GIS data taken during the satellite
attitude maneuver operation. Our motivation is to search for serendipitous hard
X-ray sources and make the ASCA Slew Survey catalog.
  During its operational life from 1993 February to 2000 July, ASCA carried out
more than 2,500 maneuver operations, and total exposure time during the
maneuver was ~415 ksec after data screening. Preliminary results are briefly
reported.


title:
XMM-Newton confirmation of Soft X-ray excess emission in clusters of
  galaxies - the discovery of O VII emission from an extended warm baryonic
  component

abstract:
  We investigate a sample of 14 clusters of galaxies observed with XMM-Newton
in a search for soft X-ray excess emission. In five of these clusters a
significant soft excess is evident. This soft X-ray excess is compared with the
thermal emission from both the hot intracluster gas and any cooling (flow) gas
that may be present. A warm (kT=0.2 keV), extended (several Mpc), plasma
component is particularly clear in the outer parts of the cluster, where the
normal cluster X-ray emission is weak. This warm component causes both a
thermal soft X-ray excess at low energies (below 0.4-0.5 keV), as well as O VII
line emission with a redshift consistent with a cluster origin, and not easily
interpreted as Galactic foreground emission. The intensity of this component is
commensurate with what has been measured before with the ROSAT PSPC in the 1/4
keV band. We attribute this component to emission from intercluster filaments
of the Warm-Hot Intergalactic Medium in the vicinity of these clusters. For the
central regions of clusters the detection of lines in the soft X-ray spectrum
is more difficult, due to the predominance of the X-ray emitting hot plasma
there, hence we cannot discriminate between the thermal and nonthermal origin
of the soft excess, leaving several options open. These include thermal
emission from warm filaments seen in projection in front of or behind the
cluster center, thermal or nonthermal emission in the cluster core itself
related to magnetic reconnection, or Inverse Compton emission from the cosmic
microwave background on relativistic electrons.


title: CNO at the surface of low and intermediate MS stars

abstract:
  Recent studies of spectral lines of the CNO elements in the Sun and unevolved
disk and halo stars show that most published abundance data may be affected by
systematic errors due to inadequate 1D modelling of stellar atmospheres. This
raises doubts about previously derived trends of CNO abundances as a function
of [Fe/H]. In this review we concentrate on abundance ratios derived from weak
spectral features with similar dependences on temperature and pressure, which
ratios are then relatively insensitive to 3D model atmosphere effects and to
effective temperature and surface gravity. The recent controversy about the
trend of [O/Fe] vs. [Fe/H] is discussed, new results for C/O ratios as
determined from forbidden lines and high excitation neutral lines are
presented, and N/C ratios derived from NH and CH lines are commented on.


title: The chemistry of compact planetary nebulae

abstract:
  We report high-sensitivity millimetre observations of several molecular
species (13CO, HCN, HNC, CN, HCO+ and N2H+) in a sample of compact planetary
nebulae. Some species such as HCO+ and CN are particularly abundant compared to
envelopes around AGB stars or even interstellar clouds. We have estimated the
following average values for the column densities ratios: CN/HCN~2.6,
HCO+/HCN~0.5, and HNC/HCN~0.4. Thus, the chemical composition of the molecular
envelopes in these compact PNe appears somewhat intermediate between the
composition of proto-PNe (such as CRL 2688 or CRL 618) and well evolved PNe
(such as the Ring, M4--9, or the Helix). From observations of the CO
isotopomers, we have estimated that the 12C/13C ratio is in the range 10 ~<
12C/13C ~< 40. These values are below those expected from standard asymptotic
giant branch models and suggest non-standard mixing processes. The observed
molecular abundances are compared to very recent modelling work, and we
conclude that the observations are well explained, in general terms, by
time-dependent gas-phase chemical models in which the ionization rate is
enhanced by several orders of magnitude with respect to the average
interstellar value. Thus, our observations confirm that the chemistry in the
neutral shells of PNe is essentially governed by the high energy radiation from
the hot central stars. The complexity of the chemical processes is increased by
numerous factors linked to the properties of the central star and the geometry
and degree of clumpiness of the envelope. Several aspects of the PN chemistry
that remains to be understood are discussed within the frame of the available
chemical models.


title: VLT spectroscopy of globular clusters in the Sombrero galaxy

abstract:
  We have obtained intermediate-resolution VLT spectroscopy of 75 globular
cluster candidates around the Sa galaxy M104 (NGC4594). Fifty-seven candidates
out to ~ 40 kpc in the halo of the galaxy were confirmed to be bona-fide
globular clusters, 27 of which are new. A first analysis of the velocities
provides only marginal evidence for rotation of the cluster system. From Hbeta
line strengths, almost all of the clusters in our sample have ages that are
consistent, within the errors, with Milky Way globular clusters. Only a few
clusters may be 1-2 Gyr old, and bulge and halo clusters appear coeval. The
absorption line indices follow the correlations established for the Milky Way
clusters. Metallicities are derived based upon new empirical calibrations with
Galactic globular clusters taking into account the non-linear behavior of some
indices (e.g., Mg2). Our sample of globular clusters in NGC4594 spans a
metallicity range of -2.13 < [Fe/H] < +0.26 dex, and the median metallicity of
the system is [Fe/H] = -0.85. Thus, our data provide evidence that some of the
clusters have super-solar metallicity. Overall, the abundance distribution of
the cluster system is consistent with a bimodal distribution with peaks at
[Fe/H] ~- 1.7 and -0.7. However, the radial change in the metallicity
distribution of clusters may not be straightforwardly explained by a varying
mixture of two sub-populations of red and blue clusters.


title: Young compact objects in the Solar vicinity

abstract:
  We present Log N -- Log S distribution for close-by young isolated neutron
stars. On the basis of this distribution it is shown that the seven ROSAT
isolated neutron stars (if they are young cooling objects) are genetically
related to the Gould Belt. We predict, that there are about few tens
unidentified close-by young isolated neutron stars in the ROSAT All-Sky Survey.
The possibility that these seven peculiar sources contain a neutron star less
massive and more magnetized then in ordinary radiopulsars is also discussed. In
the aftermath of relatively close recent supernova explosions (1 kpc around the
Sun, a few Myrs ago), a few black holes might have been formed, according to
the local initial mass function. We thus discuss the possibility of determining
approximate positions of close-by isolated black holes using data on runaway
stars and simple calculations of binary evolution and disruption.


title: Wide field photometry of the M104 globular cluster system

abstract:
  We present preliminary results of a wide field study of the globular cluster
system of NGC4594, the Sombrero galaxy. The galaxy was observed in B, V, and R
using the Wide Field Imager on the ESO 2.2m telescope. Using color and shape
criteria to select a sample of highly probable globular cluster candidates, we
measured the radial density profile of clusters out to 40' (100 Kpc) in the
galaxy halo. The colors are consistent with the bimodal color distribution
observed in previous studies. The red cluster candidates show a clear central
concentration relative to the blue clusters. The population of red clusters
does not appear significantly flattened, thus indicating that they are
associated to the galaxy bulge rather than to the disk.


title:
Spectro-Polarimetric search for hidden AGNs in four southern
  Ultraluminous Infrared Galaxies

abstract:
  We report on a spectro-polarimetric analysis of four southern Ultra-Luminous
Infrared Galaxies (ULIRGs), aimed at constraining the presence of hidden broad
AGN lines. For IRAS 19254--7245 ({\sl The Superantennae}) we find evidence for
a significant level of polarized light in the H$\alpha$ line with FWHM$>$2300
km/s. Some degree of polarization is also detected in IRAS 20551-4250, though
with lower significance. In the two other sources (IRAS 20100--4156 and IRAS
22491--1808) no polarized signals are detected. Although it is unclear from the
present data if the origin of polarization is due to reflected light from an
AGN or more simply to dichroic transmission by a dust slab, we find interesting
correlation between the presence of polarized components in the optical spectra
and independent evidence for AGN emissions in hard X-rays and the far-IR.


title:
A new look at the pulsating DB white dwarf GD 358:Line-of-sight velocity
  measurements and constraints on model atmospheres

abstract:
  We report on our findings of the bright, pulsating, helium atmosphere white
dwarf GD 358, based on time-resolved optical spectrophotometry. We identify 5
real pulsation modes and at least 6 combination modes at frequencies consistent
with those found in previous observations. The measured Doppler shifts from our
spectra show variations with amplitudes of up to 5.5 km/s at the frequencies
inferred from the flux variations. We conclude that these are variations in the
line-of-sight velocities associated with the pulsational motion. We use the
observed flux and velocity amplitudes and phases to test theoretical
predictions within the convective driving framework, and compare these with
similar observations of the hydrogen atmosphere white dwarf pulsators (DAVs).
The wavelength dependence of the fractional pulsation amplitudes (chromatic
amplitudes) allows us to conclude that all five real modes share the same
spherical degree, most likely, l=1. This is consistent with previous
identifications based solely on photometry. We find that a high signal-to-noise
mean spectrum on its own is not enough to determine the atmospheric parameters
and that there are small but significant discrepancies between the observations
and model atmospheres. The source of these remains to be identified. While we
infer T_eff=24kK and log g~8.0 from the mean spectrum, the chromatic
amplitudes, which are a measure of the derivative of the flux with respect to
the temperature, unambiguously favour a higher effective temperature, 27kK,
which is more in line with independent determinations from ultra-violet
spectra.


title: The Galaxy Cluster RBS380: Xray and Optical Analysis

abstract:
  We present X-ray and optical observations of the z=0.52 galaxy cluster
RBS380. This is the most distant cluster in the ROSAT Bright Source catalog.
The cluster was observed with the CHANDRA satellite in September 2000. The
optical observations were carried out with the NTT-SUSI2 camara in filters V
and R in August and September 2001. The preliminary conclusions are that we see
a very rich optical galaxy cluster but with a relative low X-ray luminosity. We
also compare our results to other clusters with similar properties.


title: Extremely hard GRB spectra prune down the forest of emission models

abstract:
  We consider the evidence for very hard low energy spectra during the prompt
phase of Gamma-Ray Bursts (GRB). In particular we examine the spectral
evolution of GRB 980306 together with the detailed analysis of some other
bursts already presented in the literature (GRB 911118, GRB 910807, GRB 910927
and GRB 970111), and check for the significance of their hardness (i.e.
extremely steep spectral slopes below the $EF_{E}$ peak) by applying different
tests. These bursts, detected by the Burst And Transient Source Experiment
(BATSE) in the $\sim 30$ keV -- 2 MeV energy range, are sufficiently bright to
allow time resolved spectral studies on time intervals of the order of tenths
of a second. We discuss the hard spectra of these bursts and their evolution in
the context of several non--thermal emission models, which all appear
inadequate to account for these cases. The extremely hard spectra, which are
detected in the early part of the BATSE light curve, are also compared with a
black body spectral model: the resulting fits are remarkably good, except for
an excess at high energies (in several cases) which could be simply accounted
for by the presence of a supra--thermal component. The findings on the possible
thermal character of the evolving spectrum and the implications on the GRB
physical scenario are considered in the frameworks of photospheric models for a
fireball which is becoming optically thin, and of Compton drag models, in which
the fireball boosts "ambient" seed photons by its own bulk motion. Both models,
according to simple estimates, appear to be qualitatively and quantitatively
consistent with the found spectral characteristics, although their possible
caveats are discussed.


title: The USNO-B Catalog

abstract:
  USNO-B is an all-sky catalog that presents positions, proper motions,
magnitudes in various optical passbands, and star/galaxy estimators for
1,042,618,261 objects derived from 3,643,201,733 separate observations. The
data were obtained from scans of 7,435 Schmidt plates taken for the various sky
surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky
coverage, completeness down to V = 21, 0.2 arcsecond astrometric accuracy at
J2000, 0.3 magnitude photometric accuracy in up to five colors, and 85%
accuracy for distinguishing stars from non-stellar objects. A brief discussion
of various issues is given here, but the actual data are available from
http://www.nofs.navy.mil and other sites.


title:
A revised calibration of the Mv-W(OI 7774) relationship using Hipparcos
  data: Its application to Cepheids and evolved stars

abstract:
  A new calibration of the Mv-W(OI 7774) relationship has been calculated using
better estimates of reddenings and distances to a sample of 27 calibrator stars
of A-G spectral types, based on accurate parallaxes and proper motions from the
Hipparcos and Tycho catalogues. The present calibration predicts absolute
magnitude with accuracies of $\pm$ 0.38 mag. for a sample covering a large
range of Mv, from -9.5 to $+0.35$ mag.
  The colour term included in a previous paper has been dropped since its
inclusion was not bringing any significant improvement to the calibration. The
variation of the OI 7774 feature in the classical cepheid SS Sct has been
studied. We calculated a phase-dependent correction to random phase OI feature
strengths in Cepheids, such that it predicts mean absolute magnitudes using the
above calibration. After applying such correction, we could increase the list
of calibrators to 58 by adding Mv and OI triplet strength data for 31 classical
Cepheids.
  The standard error of the calibration using the composite sample was
comparable to that obtained from the primary 27 calibrators, showing that it is
possible to calculate mean Cepheid luminosities from random phase observations
of the OI7774 feature. We use our derived calibrations to estimate Mv for a set
of evolved objects to be able to locate their positions in the H-R diagram.


title: CMB Temperature and Polarization Anisotropy Fundamentals

abstract:
  The tremendous experimental progress in cosmic microwave background (CMB)
temperature and polarization anisotropy studies over the last few years has
helped establish a standard paradigm for cosmology at intermediate epochs and
has simultaneously raised questions regarding the physical processes at the two
opposite ends of time. What is the physics behind the source of structure in
the universe and the dark energy that is currently accelerating its expansion?
We review the acoustic phenomenology that forms the cornerstone of the standard
cosmological model and discuss internal consistency relations which lend
credence to its interpretation. We discuss future milestones in the study of
CMB anisotropy that have implications for inflationary and dark energy models.
These include signatures of gravitational waves and gravitational lensing in
the polarization fields and secondary temperature anisotropy from the transit
of CMB photons across the large-scale structure of the universe.


title:
The production mechanism of radio jets in AGN and quasar grand
  unification

abstract:
  Recent advances in estimating black hole masses for AGN show that radio
luminosity is dependent on black hole mass and accretion rate. In this paper we
outline a possible scheme for unifying radio-quiet and radio-loud AGN. We take
the ``optimistic'' view that the mass and spin of the central black hole, the
accretion rate onto it, plus orientation and a weak environmental dependence,
fully determine the observed properties of AGN.


title: Jodrell Bank Timing Astrometry

abstract:
  More than 500 pulsars are regularly observed with the 76-m Lovell radio
telescope at Jodrell Bank Observatory. Precise positional and rotational
parameters have been obtained from observations spanning between 6 and 34 years
for over 300 of these pulsars. The parameters were determined by fitting a
timing model to whitened pulse arrival times. In this paper, the technique used
to whiten the timing residuals is summarised and the astrometric measurements
are compared to proper motions determined earlier with interferometers. This
novel approach has led to the first proper motion measurements for 111 pulsars
and improved results for 15 pulsars.


title:
The Ringed Spiral Galaxy NGC 4622. I. Photometry, Kinematics, and the
  Case for Two Strong Leading Outer Spiral Arms

abstract:
  The intriguing nearly face-on southern ringed spiral galaxy NGC 4622, the
first galaxy definitively shown to have leading spiral structure, is revisited
in this paper with new images from the Hubble Space Telescope's WFPC2, together
with ground-based optical and near-IR imaging, and a Fabry-Perot H-alpha
velocity field. The data provide new information on the disk/bulge/halo mix,
rotation curve, star formation in the galaxy, and the sense of winding of its
prominent spiral arms. Previously, we suggested that the weaker, inner single
arm most likely has the leading sense, based on a numerical simulation. Now,
taking advantage of HST resolution and using de Vaucouleurs' standard
extinction and reddening technique to determine the near side of the galaxy's
slightly tilted disk, we come to the more surprising conclusion that the two
strong outer arms have the leading sense. We suggest that this highly unusual
configuration may be the result of a past minor merger or mild tidal encounter.
Possible evidence for a minor merger is found in a short, central dust lane,
although this is purely circumstantial and an unrelated interaction with a
different companion could also be relevant. The leading arms may be allowed to
persist because NGC 4622 is dark halo-dominated (i.e., not ``maximum disk'' in
the inner regions) and displays a significantly rising rotation curve. The new
HST observations also reveal a rich globular cluster system in the galaxy. The
mean color of these clusters is <(V-I)o> = 1.04 and the specific frequency is
3.4$\pm$0.6. The luminosity function of these clusters confirms the membership
of NGC 4622 in the Centaurus Cluster.


title: A Search for HI in Five Ellipticals with Fine Structure

abstract:
  We report on VLA HI spectral line observations of five early-type galaxies
classified as optically peculiar due to the presence of jets, ripples or other
optical "fine structure". We detect HI within the primary beam (30' HPBW) in
four of the five systems. However, in only one case is this gas associated with
the targeted elliptical galaxy. In the other cases the HI is associated with a
nearby gas-rich disk or dwarf galaxy. The one HI detection is for NGC 7626,
where we tentatively detect an HI cloud lying between 20 and 40 kpc southwest
of the galaxy center. Its origin is unclear. Our failure to detect obvious
tidal HI features suggests that if these fine-structure ellipticals are
remnants of disk galaxy mergers, either the progenitors were gas poor, or they
are well evolved and any gaseous tidal features have dispersed and/or been
converted into other phases. Our targeted systems all reside in groups or
clusters, and it seems likely that tidal HI is shorter lived in these
environments than suggested by studies of more isolated merger remnants.


title: The Massive Binary Pulsar J1740-3052

abstract:
  The young pulsar J1740-3052 is in an 8-month orbit with a companion of at
least 11 solar masses. We present multifrequency GBT and Parkes timing
observations, and discuss implications for the nature of the companion.


title: High-Resolution Observations of PSR B1828-11

abstract:
  We present high-time-resolution observations of the young precessing pulsar
B1828-11, which yield clues to the true beam shape and the fundamental
precession period.


title: Subaru Prime Focus Camera -- Suprime-Cam --

abstract:
  We have built an 80-mega pixels (10240 X 8192) mosaic CCD camera, called
Suprime-Cam, for the wide-field prime focus of the 8.2 m Subaru telescope.
Suprime-Cam covers a field of view 34' X 27', a unique facility among the the
8-10 m class telescopes, with a resolution of 0.''202 per pixel. The focal
plane consists of ten high-resistivity 2k X 4k CCDs developed by MIT Lincoln
Laboratory, which are cooled by a large stirling-cycle cooler. The CCD readout
electronics was designed to be scalable, which allows the multiple read-out of
tens of CCDs. It takes 50 seconds to readout entire arrays. We designed a
filter-exchange mechanism of the jukebox type that can hold up to ten large
filters (205 X 170 X 15 mm^3). The wide-field corrector is basically a
three-lens Wynne-type, but has a new type of atmospheric dispersion corrector.
The corrector provides a flat focal plane and an un-vignetted field of view of
30' in diameter. The achieved co-planarity of the focal array mosaic is smaller
than 30 micron peak-to-peak, which realizes mostly the seeing limited image
over the entire field. The median seeing in the Ic-band, measured over one year
and a half, is 0.''61. The PSF anisotropy in Suprime-Cam images, estimated by
stellar ellipticities, is about 2% under this median seeing condition. At the
time of commissioning, Suprime-Cam had the largest survey speed, which is
defined as the field of view multiplied by the primary mirror area of the
telescope, among those cameras built for sub-arcsecond imaging.


title:
Modeling Intra-Cluster Gas in Triaxial Dark Halos : An Analytical
  Approach

abstract:
  We present the first physical model for the non-spherical intra-cluster gas
distribution in hydrostatic equilibrium under the gravity of triaxial dark
matter halos. Adopting the concentric triaxial density profiles of the dark
halos with constant axis ratios proposed by Jing & Suto (2002), we derive an
analytical expression for the triaxial halo potential on the basis of the
perturbation theory, and find the hydrostatic solutions for the gas density and
temperature profiles both in isothermal and polytropic equations of state. The
resulting iso-potential surfaces are well approximated by triaxial ellipsoids
with the eccentricities dependent on the radial distance. We also find a
formula for the eccentricity ratio between the intra-cluster gas and the
underlying dark halo. Our results allow one to determine the shapes of the
underlying dark halos from the observed intra-cluster gas through the X-ray
and/or the Sunyaev-Zel'dovich effects clusters.


title:
Orbital Decay and Tidal Disruption of a Star Cluster: Analytical
  Calculation

abstract:
  The orbital decay and tidal disruption of a star cluster in a galaxy is
studied in an analytical manner. Owing to dynamical friction, the star cluster
spirals in toward the center of the galaxy. Simultaneously, the galactic tidal
field strips stars from the outskirts of the star cluster. Under an assumption
that the star cluster undergoes a self-similar evolution, we obtain the
condition and timescale for the star cluster to reach the galaxy center before
its disruption. The result is used to discuss the fate of so-called
intermediate-mass black holes with >10^3 M(sun) found recently in young star
clusters of starburst galaxies and also the mass function of globular clusters
in galaxies.


title: The rotation curve and mass-distribution in highly flattened galaxies

abstract:
  A new method is developed which permits the reconstruction of the
surface-density distribution in the galactic disk of finite radius from an
arbitrary smooth distribution of the angular velocity via two simple
quadratures. The existence of upper limits for disk's mass and radius during
the analytic continuation of rotation curves into the hidden (non-radiating)
part of the disk is demonstrated.


title: Pulsar observations at Mt. Pleasant

abstract:
  Two daily pulsar monitoring programs are progressing at the Mount Pleasant
Observatory, Hobart, Tasmania, Australia. A new system involving the 26-metre
radio telescope monitors 10 young pulsars daily and is focussed on
near-real-time glitch finding. This will allow Target of Opportunity
observations to measure post-glitch heating of the neutron star surface
(Helfand, Gotthelf, & Halpern 2000).
  The 14-metre continues its 21st year of daily monitoring of the Vela pulsar
with a recent comprehensive frontend upgrade. This is prior to an upgrade of
the backend equipment currently in progress. The 14-metre observed the most
recent glitch of the Vela pulsar in January 2000 to the highest time resolution
of any glitch and revealed a particularly short-term decay component (Dodson,
McCulloch, & Lewis 2002). This decay component will provide constraints to the
nature of the coupling of the stellar crust to the liquid interior.


title: Local galaxy flows within 5 Mpc

abstract:
  We present Hubble Space Telescope/WFPC2 images of sixteen dwarf galaxies as
part of our snapshot survey of nearby galaxy candidates. We derive their
distances from the luminosity of the tip of the red giant branch stars with a
typical accuracy of ~12%. The resulting distances are 4.26 Mpc (KKH 5), 4.74
Mpc (KK 16), 4.72 Mpc (KK 17), 4.66 Mpc (ESO 115-021), 4.43 Mpc (KKH 18), 3.98
Mpc (KK 27), 4.61 Mpc (KKH 34), 4.99 Mpc (KK 54), 4.23 Mpc (ESO 490-017), 4.90
Mpc (FG 202), 5.22 Mpc (UGC 3755), 5.18 Mpc (UGC 3974), 4.51 Mpc (KK 65), 5.49
Mpc (UGC 4115), 3.78 Mpc (NGC 2915), and 5.27 Mpc (NGC 6503). Based on
distances and radial velocities of 156 nearby galaxies, we plot the local
velocity-distance relation, which has a slope of H_0 = 73 km/(c * Mpc) and a
radial velocity dispersion of 85 km/s. When members of the M81 and CenA groups
are removed, and distance errors are taken into account, the radial velocity
dispersion drops to sigma_v=41 km/s. The local Hubble flow within 5 Mpc exibits
a significant anisotropy, with two infall peculiar velocity regions directed
towards the Supergalactic poles. However, two observed regions of outflow
peculiar velocity, situated on the Supergalactic equator, are far away (~50
degr.) from the Virgo/anti-Virgo direction, which disagrees with a spherically
symmetric Virgo-centric flow. About 63% of galaxies within 5 Mpc belong to
known compact and loose groups. Apart from them, we found six new probable
groups, consisting entirely of dwarf galaxies.


title: Near-infrared spectroscopy of Seyfert galaxies

abstract:
  Results from near-infrared 1.5 - 2.5 micron long-slit spectroscopy of 14
nearby Seyfert galaxies are presented.


title:
Deep Fields: The Faint sub-mJy and microJy Radio Sky - A VLBI
  Perspective

abstract:
  Until recently, VLBI targets have been drawn almost exclusively from the
brightest and most compact radio sources in the sky, with typical flux
densities well in excess of a few tens of mJy. These sources are predominantly
identified with Active Galactic Nuclei (AGN), located at cosmological
distances. In this lecture I will attempt to summarise what is currently known
about the general properties of the faint sub-mJy and microJy radio source
population, as determined from deep multi-wavelength studies of the HDF-N. In
particular, I will try to provide a VLBI perspective, describing the first
deep, wide-field, VLBI pilot observations of the HDF, together with a summary
of the main results. The role VLBI can play in future high resolution studies
of faint radio sources is also addressed.


title:
Axi-symmetric models of ultraviolet radiative transfer with applications
  to circumstellar disk chemistry

abstract:
  A new two-dimensional axi-symmetric ultraviolet radiative transfer code is
presented, which is used to calculate photodissociation and ionization rates
for use in chemistry models of flaring circumstellar disks. Scattering and
absorption of photons from the central star and from the interstellar radiation
field are taken into account. The molecules are effectively photodissociated in
the surface layer of the disk, but can exist in the intermediate, moderately
warm layers. A comparison has been made with an approximate 2D ray-tracing
method and it was found that the latter underestimates the ultraviolet field
and thus the molecular photodissociation rates below the disk surface. The full
2D results show significantly higher abundances of radicals such as CN and C2H
than previous work, partly due to the fact that CO is dissociated to greater
depths. Results for different stellar radiation fields are also presented. The
CN/HCN ratio shows a strong dependence on the stellar spectrum, whereas other
ratios such as HCO+/CO show only little variation.


title: On the Stability of the 421-day Periodicity in A0538-66

abstract:
  In this paper we analyse 70 years of archival Harvard and Schmidt plate data
of the 16.6 d Be X-ray binary A0538-66 in order to search for the presence of
the long-term period of 420.82 +/- 0.79 d found in MACHO photometry (Alcock et
al. 2001). We find evidence for a long-term period of 421.29 +/- 0.95 d in the
archival data, and examine its stability. We also combine the archival and
MACHO datasets in order to improve the accuracy of the orbital period
determination, using a cycle-counting analysis to refine its value to 16.6460
+/- 0.0004 d. We also test the model proposed in our previous paper (Alcock et
al. 2001) with observations documented in the literature for A0538-66 from
1980-1995, constraining the system inclination to be i > 74.9 +/- 6.5 deg.


title: Future prospects: Merging data with models

abstract:
  Globular clusters are stellar dynamical systems which evolve on stellar
evolutionary and both internal and external dynamical timescales. Quantitative
comparison of cluster properties with realistic evolutionary dynamical models
is becoming feasible, and will underpin the subject in the next few years. A
few examples of the types of analysis becoming possible are presented.


title:
Modification of cluster radio halo appearance by the thermal
  Sunyaev-Zeldovich effect

abstract:
  We discuss the consequences of the spectral and morphological modification of
galaxy cluster radio halos due to the Sunyaev-Zeldovich (SZ) effect for the
interpretation of existing and upcoming high frequency radio observations.
Likely these modifications have affected the interpretation of the existing
Coma cluster radio data. The radio halo emission visible at low (< 5 GHz)
frequencies is at higher (> 10 GHz) frequencies completely over-compensated by
the thermal SZ decrement. Thus, the total radio emission of a galaxy cluster
goes through zero (in comparison to the constant cosmic microwave background
(CMB) emission) at a frequency of several GHz. Since the radio halo brightness
has a narrow radial profile compared to the SZ decrement, a central emission
region is surrounded by a decrement within the intermediate frequency range of
several GHz. The size of this emission regions shrinks with increasing
frequency until the decrement dominates everywhere in the cluster.


title: Heavy Nuclei from RHIC to the Cosmos

abstract:
  Ultra-relativistic heavy ion collisions produce a high-temperature,
thermalized system that may mimic the conditions present shortly after the big
bang. This writeup will given an overview of early results from the
Relativistic Heavy Ion Collider (RHIC), and discuss what we have learned about
hot, strongly interacting nuclear systems. The thermal and chemical composition
of the system will be discussed, along with observables that are sensitive to
the early evolution of the system. I will also discuss the implications of the
RHIC results for cosmic ray air showers.


title: Relativistic MHD jets and the GRBs

abstract:
  High velocity highly collimated beams of plasma -- the jets -- are known as a
general phenomenon among astrophysical sources of different energy and spatial
scale. The common MHD scenario of astrophysical jet formation allows to
describe the different jet sources by a scaling of the jet magnetization. In
this paper we apply the MHD jet theory for GRB parameters and find indeed that
main features as ultra-relativistic motion and strong collimation can be
explained. Others, like GRB time-variability and the bi-modal GRB duration are
(yet) beyond a MHD description.


title:
Polarization curves of GRB afterglows predicted by the universal jet
  structure

abstract:
  It has been recently proposed that current burst and afterglow observations
can be accounted for by a top hat jet structure as well as by a more universal
structured outflow, in which the energy carried by the flow is maximum at the
jet spine, decreasing outwards as a power-law with the off-axis angle. To pin
down the GRBs jet structure is important in order to quantify the total energy
released by the unknown engine and put constrains on its nature. In paper we
will review the most popular GRBs jet structures, focusing on the predicted
observed properties that could discriminate between them. In particular the
behaviour of linearly polarised emission during the afterglow phase seems very
promising, since the degree and temporal dependence are predicted to be very
different from model to model. In addition, polarization measurements and
detections are accumulating fast enouqgh to lead soon to a comprehension of
magnetic field and GRBs jet configurations.


title: Comments on Inferences of Star Formation Histories and Birthlines

abstract:
  Palla & Stahler have recently argued that star formation in Taurus and other
nearby molecular clouds extends over a period of at least 10 Myr, implying
quasi-static cloud evolution and star formation. Their conclusions contradict
other recent results indicating that molecular clouds are transient objects and
star formation proceeds rapidly. The Palla & Stahler picture implies that most
molecular clouds should have extremely low rates of star formation, and that in
such inactive stages the stellar initial mass function should be strongly
skewed toward producing stars with masses $\gtrsim 1 \msun$; neither prediction
is supported by observations. I show that the Palla & Stahler conclusions for
Taurus depend almost entirely on a small number of stars with masses $\gtrsim 1
\msun$; the lower-mass stars show no evidence for such an extended period of
star formation. I further show that most of the stars apparently older than 10
Myr in the direction of Taurus are probably foreground non-members. I also
present birthline calculations which support the idea that the ages of the
stars with masses $\gtrsim 1 \msun$ have been systematically overestimated
because ``birthline'' age corrections have been underestimated; such birthlines
would eliminate the need to postulate skewed initial mass functions. The
simplest and most robust explanation of current observations characterizing the
vast majority of young stars in molecular clouds is that cloud and star
formation is rapid and dynamic.


title:
The Orbits of Terrestrial Planets in the Habitable Zones of Known
  Exoplanetary Systems

abstract:
  We show that terrestrial planets could survive in variously restricted
regions of the habitable zones of 47 Ursae Majoris, Epsilon Eridani, and Rho
Coronae Borealis, but nowhere in the habitable zones of Gliese 876 and Upsilon
Andromedae. The first three systems between them are representative of a large
proportion of the 90 or so extrasolar planetary systems discovered by mid-2002,
and thus there are many known systems worth searching for terrestrial planets
in habitable zones. We reach our conclusions by launching putative Earth-mass
planets in various orbits and following their fate with a mixed-variable
symplectic integrator.


title: Galaxy Formation: Clues from the Milky Way

abstract:
  Stellar Populations are the fossil record of Galactic evolution.
Interpretation of this record in the Local Group allows one to determine
reliably the dominant physics controlling the evolution of those galaxies which
are typical of the luminosity in the Universe, and is an essential prerequisite
to understanding necessarily limited data at high redshifts. In our Galaxy, the
key issues are the places and times of formation and merger of the oldest
stellar populations : the halo, thick disk and bulge - and their overlaps and
evolutionary relationships, if any. New results on studies of the stellar
initial mass function at high redshift, the stellar populations of the Galactic
bulge, and the merger history of the Galactic disk are reviewed.


title: X-ray properties of spiral galaxies

abstract:
  X-ray studies of nearby spiral galaxies with star formation allow us to
investigate temperature and spatial distribution of the hot diffuse plasma, and
to carry out individual and statistical studies of different classes of
discrete sources (low- and high-mass X-ray binaries, Supernova remnants,
supersoft and ultra-luminous sources). In particular, we briefly review the
different models proposed to explain the ultra-luminous sources. We can then
use the X-ray properties of a galaxy to probe its star formation history. We
choose the starburst spiral M83 to illustrate some of these issues.


title: The AST/RO Survey of the Galactic Center Region. I. The Inner 3 Degrees

abstract:
  We present fully-sampled maps of 461 GHz CO (4-3), 807 GHz CO (7-6), and 492
GHz [CI] (3P1-3P0) emission from the inner 3 degrees of the Galactic Center
region taken with the Antarctic Submillimeter Telescope and Remote Observatory
(AST/RO) in 2001--2002. The data cover -1.3 < l < 2, -0.3 < b < 0.2 with 0.5
arcmin spacing, resulting in spectra in 3 transitions at over 24,000 positions
on the sky. The CO (4-3) emission is found to be essentially coextensive with
lower-J transitions of CO. The CO (7-6) emission is spatially confined to a far
smaller region than the lower-J CO lines. The [CI] (3P1-3P0) emission has a
spatial extent similar to the low-J CO emission, but is more diffuse. Bright CO
(7-6) emission is detected in the well-known Galactic Center clouds Sgr A and
Sgr B. We also detect CO (4-3) and CO (7-6) absorption from spiral arms in the
galactic disk at velocities near 0 km s^-1 along the line of sight to the
Galactic Center. Analyzing our CO (7-6) and CO (4-3) data in conjunction with J
= 1 - 0 12CO and 13CO data previously observed with the Bell Laboratories 7-m
antenna, we apply a Large Velocity Gradient (LVG) model to estimate the kinetic
temperature and density of molecular gas in the inner 200 pc of the Galactic
Center region. We show maps of the derived distribution of gas density and
kinetic temperature as a function of position and velocity for the entire
region. Kinetic temperature was found to decrease from relatively high values
(>70K) at cloud edges to low values (<50K) in the interiors. Typical gas
pressures in the Galactic Center gas are n(H_2) T_kin approx 10^5.2 K cm^-3. We
also present an (l,b) map of molecular hydrogen column density derived from our
LVG results.


title:
The impact of mass loss on star cluster formation. II. Numerical N-body
  integration & further applications

abstract:
  We subject to an N-body numerical investigation our analysis of Paper I on
the survival of stellar clusters undergoing rapid mass loss. We compare
analytical tracks of bound mass-fraction {\it vs} star formation efficiency
$\epsilon$ to those obtained with N-body integration. We use these to argue
that stellar clusters must develop massive cores of high-binding energy if they
are to remain bound despite a star formation efficiency as low as 30% or lower
suggested by observations. The average local virial ratio $<\sigma^2/|\phi|>$
is introduced to classify bound clusters as function of their critical
$\epsilon$ for dissolution. Clusters dissolving at lower $\epsilon$ achieve the
lowest ratio. We applied this classification parameter successfully to
Michie-King and Hernquist-type distribution functions. The Plummer sphere is
exceptional in that it defies this and other classification parameters we
tried.
  The reasons for the discrepancy include less effective energy redistribution
during the expansion phase for this case.


title: Chandra Observation of the Cooling Flow Cluster Abell 2052

abstract:
  We present an analysis of the Chandra X-ray observation of Abell 2052,
including large scale properties of the cluster as well as the central region
which includes the bright radio source, 3C 317. We present temperature and
abundance profiles using both projected and deprojected spectral analyses. The
cluster shows the cooling flow signatures of excess surface brightness above a
beta- model at the cluster center, and a temperature decline into the center of
the cluster. The heavy element abundances initially increase into the center,
but decline within 30 arcsec. Temperature and abundance maps show that the
X-ray bright shells surrounding the radio source are the coolest and least
abundant regions in the cluster. The mass-deposition rate in the cooling flow
is 26 < Mdot < 42 Msun/yr. This rate is ~ a factor of three lower than the
rates found with previous X-ray observatories. Based on a stellar population
analysis using imaging and spectra at wavelengths spanning the far UV to the
NIR, we find a star formation rate of 0.6 Msun/yr within a 3 arcsec radius of
the nucleus of the central cluster galaxy. Total and gas mass profiles for the
cluster are also determined. We investigate additional sources of pressure in
the X-ray holes formed by the radio source, and limit the temperature of any
hot, diffuse, thermal component which provides the bulk of the pressure in the
holes to kT > 20 keV. We calculate the magnetic field in the bright-shell
region and find B ~ 11 \muG. The current luminosity of the central AGN is L_X =
7.9 x 10^41 erg/s, and its spectrum is well-fitted by a power-law model with no
excess absorption above the Galactic value. The energy output from several
radio outbursts, occurring episodically over the lifetime of the cluster, may
be sufficient to offset the cooling flow near the center. (Abridged)


title: Diffusive Nuclear Burning in Neutron Star Envelopes

abstract:
  We present a new mode of hydrogen burning on neutron stars (NSs) called
diffusive nuclear burning (DNB). In DNB, the burning occurs in the
exponentially suppressed tail of hydrogen that extends to the hotter regions of
the envelope where protons are readily captured. Diffusive nuclear burning
changes the compositional structure of the envelope on timescales $\sim
10^{2-4} {\rm yrs}$, much shorter than otherwise expected. This mechanism is
applicable to the physics of young pulsars, millisecond radio pulsars (MSPs)
and quiescent low mass X-ray binaries (LMXBs).


title: High-velocity regions in planetary nebulae

abstract:
  The internal velocity fields of planetary nebulae are studied with a
resolution of 5 km s$^{-1}$. We analyze deep echelle spectra from three nebulae
in the Bulge, the Sagittarius Dwarf and the SMC. No effects of metallicity is
seen, except possibly a slower onset of the fast wind from the central star.
Robust evidence is found for the existence of a high-velocity shock at the
inner edges of the nebulae. Such a shock is predicted in hydrodynamical models
but had not previously been observed. The shock gas is accelerated by the fast
wind from the central star. A similar shock at the outer edges traces the
expansion of the ionized shell into the ambient AGB wind. Evidence for
localized regions of high velocity is also found from lines of intermediate
excitation, for two of nebulae. We explore several possible interpretations:
(1) an embedded shock at intermediate radii, as predicted by hydrodynamic
models at the position of the outer edge of the swept-up inner shell; (2)
deviations form spherical symmetry, where in some directions the
intermediate-excitation lines extend into the region of the outer shock; (3) An
intermediate swept-up shell, as seen in some Galactic planetary nebulae. The
remaining nebula, with a [WC] star, shows strong turbulence. This may trace a
superposition of many embedded shock-lets. We suggest a relation to the
time-variable [WC] wind, giving a planetary nebula subjected to a multitude of
sound waves.


title: Spectroscopy of a Globular Cluster in the Local Group dIrr NGC 6822

abstract:
  We present low-resolution Keck spectroscopy for the globular cluster H VIII
in the Local Group dIrr galaxy NGC 6822. We find the metallicity of the cluster
to be [Fe/H]= -1.58 +/- 0.28 and the age of the cluster to be 3-4 Gyr, slightly
older than but consistent with previous age estimates. H VIII seems to be more
metal-poor than most intermediate-age globular clusters in the Local Group, and
appears most similar to the anomalous Small Magellanic Cloud clusters Lindsay
113 and NGC 339.


title: The Properties of Compressible MHD and Cosmic Ray Transport

abstract:
  Turbulence is the most common state of astrophysical flows. In typical
astrophysical fluids, turbulence is accompanied by strong magnetic fields,
which has a large impact on the dynamics of the turbulent cascade. Recently,
there has been a significant breakthrough on the theory of magnetohydrodynamic
(MHD) turbulence. For the first time we have a scaling model that is supported
by both observations and numerical simulations. We review recent progress in
studies of both incompressible and compressible turbulence. We compare
Iroshnikov-Kraichnan and Goldreich-Sridhar models, and discuss scalings of
Alfven, slow, and fast waves. We discuss the implications of this new insight
into MHD turbulence for cosmic ray transport.


title:
Polarized Foreground Emission from Dust: Grain Alignment and MHD
  Turbulence

abstract:
  Aligned grains present a foreground for cosmic microwave emission studies. We
review basic physical processes involved in grain alignment and discuss the
niches for different alignment mechanisms. We show that mechanisms which were
favored for decades do not look so promising right now, while the radiative
torque mechanism ignored for more than 20 years looks quite attractive. We
discuss alignment of small rotating grains that are thought to be responsible
for 10-90 GHz anomalous foreground and polarization arising from magnetic
grains.


title: Is HCG31 undergoing a merger or a fly-by interaction?

abstract:
  We present Fabry-Perot and multi-object spectroscopy of the galaxies in
Hickson compact group 31 (HCG31). Based upon our H$\alpha$ data cubes, galaxies
A and C are a single entity, showing no discontinuity in their kinematics.
Kinematically, galaxy E is probably a component of the A+C complex; otherwise
it is a recently detached fragment. Galaxy F appears, both kinematically and
chemically, to have formed from material tidally removed from the A+C complex.
Galaxies B and G are kinematically distinct from this complex. Galaxy Q also
has a radial velocity compatible with group membership. Galaxies A, B, C, and F
have nearly identical oxygen abundances, despite spanning a luminosity range of
5$ $mag. Galaxy B's oxygen abundance is normal for its luminosity, while galaxy
F's abundance is that expected given its origin as a tidal fragment of the A+C
complex. The oxygen abundances in galaxies A and C are also understandable if
the A+C complex is a late-type spiral suffering strong gas inflow and star
formation as a result of a tidal interaction. Given the kinematics of both the
galaxies and the \ion{H}{i} gas, the oxygen abundances, and the position of
galaxy G, we propose that an interaction of galaxy G with the A+C complex,
rather than a merger of galaxies A and C, is a more complete explanation for
the tidal features and other properties of HCG31. In this case, the A+C complex
need not be a merger in progress, though this is not ruled out.


title: Inhomogeneous Big Bang Cosmology

abstract:
  In this letter, we outline an inhomogeneous model of the Big Bang cosmology.
For the inhomogeneous spacetime used here, the universe originates in the
infinite past as the one dominated by vacuum energy and ends in the infinite
future as the one consisting of "hot and relativistic" matter. The spatial
distribution of matter in the considered inhomogeneous spacetime is {\em
arbitrary}. Hence, observed structures can arise in this cosmology from
suitable "initial" density contrast. Different problems of the standard model
of Big Bang cosmology are also resolved in the present inhomogeneous model.
This inhomogeneous model of the Big Bang Cosmology predicts "hot death" for the
universe.


title:
Caught in the act: a helium-reionizing quasar near the line of sight to
  Q0302-003

abstract:
  We report the discovery of a quasar at z=3.050+/-0.003, closely coincident in
redshift with the isolated low-opacity feature seen near z~3.056 in the
otherwise black portion of the HeII Gunn-Peterson absorption trough seen toward
the z=3.286 background quasar Q0302-003, located 6.5' away on the sky. We
explore plausible models for the HeIII ionization zone created by this
neighboring quasar and its interception with the line of sight toward
Q0302-003. At its present brightness of V=20.5 and separation of D=3.2 Mpc, the
quasar can readily account for the opacity gap in the HeII absorption spectrum
of Q0302-003, provided it has been active for t_Q > 10^7 y. This is the first
clear detection of the `transverse' proximity effect and imprint of a quasar on
the intervening absorption detected along an adjacent line of sight.


title:
Inhomogeneities in the Microwave Background Radiation interpreted within
  the framework of the Quasi-Steady State Cosmology

abstract:
  We calculate the expected angular power spectrum of the temperature
fluctuations in the microwave background radiation (MBR) generated in the
quasi-steady state cosmology (QSSC). The paper begins with a brief description
of how the background is produced and thermalized in the QSSC. We then discuss
within the framework of a simple model, the likely sources of fluctuations in
the background due to astrophysical and cosmological causes. Power spectrum
peaks at $l \approx 6-10$, 180-220 and 600-900 are shown to be related in this
cosmology respectively to curvature effects at the last minimum of the scale
factor, clusters and groups of galaxies. The effect of clusters is shown to be
related to their distribution in space as indicated by a toy model of structure
formation in the QSSC. We derive and parameterize the angular power spectrum
using six parameters related to the sources of temperature fluctuations at
three characteristic scales. We are able to obtain a satisfactory fit to the
observational band power estimates of MBR temperature fluctuation spectrum.
Moreover, the values of `best fit' parameters are consistent with the range of
expected values.