title: Extragalactic water masers in bright IRAS sources

abstract:
  We report the results of a search for 22 GHz water maser emission in
IRAS-bright galaxies, using the 100-m Effelsberg telescope. In particular, we
present the details of four new maser detections (IC342, NGC2146, NGC3556, and
Arp299) and follow-up interferometric studies. A comparison between water maser
detection rates derived in the present study and those in previous similar
surveys is also presented.


title: Neutral hydrogen absorption at the center of NGC2146

abstract:
  We present 1.4 GHz HI absorption line observations towards the starburst in
NGC2146, made with the VLA and MERLIN. The HI absorption has a regular spatial
and regular velocity distribution, and does not reveal any anomaly as a sign of
an encounter with another galaxy or of a far-evolved merger.


title:
Monopole gravitational waves from relativistic fireballs driving
  gamma-ray bursts

abstract:
  Einstein's general relativity predicts that pressure, in general stresses,
play a similar role to energy density in generating gravity. The source of
gravitational field, the active gravitational mass density, sometimes referred
to as Whittaker's mass density, is not conserved, hence its changes can
propagate as monopole gravitational waves. Such waves can be generated only by
astrophysical sources with varying gravitational mass. Here we show that
relativistic fireballs, considered in modelling gamma-ray burst phenomena, are
likely to radiate monopole gravitational waves from high-pressure plasma with
varying Whittaker's mass. Also, ejection of a significant amount of initial
mass-energy of the progenitor contributes to the monopole gravitational
radiation. We identify monopole waves with h^11+h^22 waves of Eddington's
classification which propagate (in the z-direction) together with the energy
carried by massless fields. We show that the monopole waves satisfy Einstein's
equations, with a common stress-energy tensor for massless fields. The
polarization mode of monopole waves is Phi_22, i.e. these are perpendicular
waves which induce changes of the radius of a circle of test particles only
(breathing mode). The astrophysical importance of monopole gravitational waves
is discussed.


title:
A comparison of the galaxy populations in the Coma and distant clusters:
  the evolution of k+a galaxies and the role of the intracluster medium

abstract:
  The spectroscopic properties of galaxies in the Coma cluster are compared
with those of galaxies in rich clusters at $z \sim 0.5$, to investigate the
evolution of the star formation history in clusters. Luminous galaxies with
$M_V \leq -20$ and post-starburst/post-starforming (k+a) spectra which
constitute a significant fraction of galaxies in distant cluster samples are
absent in Coma, where spectacular cases of k+a spectra are found instead at
$M_V>-18.5$ and represent a significant proportion of the cluster dwarf galaxy
population. A simple inspection of their positions on the sky indicates that
this type of galaxy does not show a preferential location within the cluster,
but the bluest and strongest-lined group of k+a's lies in projection towards
the central 1.4 Mpc of Coma and have radial velocities significantly higher
than the cluster mean. We find a striking correlation between the positions of
these young and strong post-starburst galaxies and substructure in the hot
intracluster medium (ICM) identified from {\it XMM-Newton} data, with these
galaxies lying close to the edges of two infalling substructures. This result
strongly suggests that the interaction with the dense ICM could be responsible
for the quenching of the star formation (thus creating the k+a spectrum), and
possibly, for any previous starburst. The evolution with redshift of the
luminosity distribution of k+a galaxies can be explained by a ``downsizing
effect'', with the maximum luminosity/mass of actively star-forming galaxies
infalling onto clusters decreasing at lower redshift. We discuss the possible
physical origin of this downsizing effect and the implications of our results
for current scenarios of environmental effects on the star formation in
galaxies.


title: Ultraluminous X-ray Sources and Star Formation

abstract:
  Chandra observations of the Cartwheel galaxy reveal a population of
ultraluminous X-ray sources (ULXs) with lifetimes < 10^7 yr associated with a
spreading wave of star formation which began some 3 x 10^8 yr ago. A population
of high-mass X-ray binaries provides a simple model: donor stars of initial
masses M_2 > 15 Msun transfer mass on their thermal timescales to black holes
of masses M_1 > 10 Msun.
  For alternative explanations of the Cartwheel ULX population in terms of
intermediate-mass black holes (IMBH) accreting from massive stars, the inferred
production rate > 10^-6 yr^-1 implies at least 300 IMBHs, and more probably 3 x
10^4, within the star-forming ring. These estimates are increased by factors
eta^-1 if the efficiency eta with which IMBHs find companions of > 15 Msun
within 10^7 yr is <1. Current models of IMBH production would require a very
large mass ($\ga 10^{10}\msun$) of stars to have formed new clusters. Further,
the accretion efficiency must be low (< 6 x 10^-3) for IMBH binaries,
suggesting super-Eddington accretion, even though intermediate black hole
masses are invoked with the purpose of avoiding it.
  These arguments suggest either that to make a ULX, an IMBH must accrete from
some as yet unknown non-stellar mass reservoir with very specific properties,
or that most if not all ULXs in star-forming galaxies are high-mass X-ray
binaries.


title:
The Impact of the Chemical Stratification of White Dwarfs on the
  Classification of Classical Novae

abstract:
  We analyse the impact of the initial abundances of the underlying white dwarf
core on the nucleosynthesis accompanying classical nova outbursts, in the
framework of hydrodynamic models of the explosion. Specifically, we take into
account the chemical stratification of the white dwarf. It turns out that the
presence of a thick CO-buffer on top of the ONe-rich core, as results from
detailed calculations of previous evolution of the progenitor star, may lead to
significant amounts of both 7Li and 26Al, after an outburst that, due to the
lack of neon isotopes in the ejecta, would be misclassified as a non-neon nova
(i.e., CO nova).


title: Arecibo Timing and Single Pulse Observations of 18 Pulsars

abstract:
  We present new results of timing and single pulse measurements for 18 radio
pulsars discovered in 1993 - 1997 by the Penn State/NRL declination-strip
survey conducted with the 305-m Arecibo telescope at 430 MHz. Long-term timing
measurements have led to significant improvements of the rotational and the
astrometric parameters of these sources, including the millisecond pulsar, PSR
J1709+2313, and the pulsar located within the supernova remnant S147, PSR
J0538+2817. Single pulse studies of the brightest objects in the sample have
revealed an unusual "bursting" pulsar, PSR J1752+2359, two new drifting
subpulse pulsars, PSR J1649+2533 and PSR J2155+2813, and another example of a
pulsar with profile mode changes, PSR J1746+2540. PSR J1752+2359 is
characterized by bursts of emission, which appear once every 3-5 min. and decay
exponentially on a ~45 sec timescale. PSR J1649+2533 spends ~30% of the time in
a null state with no detectable radio emission.


title: Ten-Micron Observations of Nearby Young Stars

abstract:
  (abridged) We present new 10-micron photometry of 21 nearby young stars
obtained at the Palomar 5-meter and at the Keck I 10-meter telescopes as part
of a program to search for dust in the habitable zone of young stars. Thirteen
of the stars are in the F-K spectral type range ("solar analogs"), 4 have B or
A spectral types, and 4 have spectral type M. We confirm existing IRAS
12-micron and ground-based 10-micron photometry for 10 of the stars, and
present new insight into this spectral regime for the rest. Excess emission at
10 micron is not found in any of the young solar analogs, except for a possible
2.4-sigma detection in the G5V star HD 88638. The G2V star HD 107146, which
does not display a 10-micron excess, is identified as a new Vega-like
candidate, based on our 10-micron photospheric detection, combined with
previously unidentified 60-micron and 100-micron IRAS excesses. Among the
early-type stars, a 10-micron excess is detected only in HD 109573A (HR 4796A),
confirming prior observations; among the M dwarfs, excesses are confirmed in AA
Tau, CD -40 8434, and Hen 3-600A. A previously suggested N band excess in the
M3 dwarf CD -33 7795 is shown to be consistent with photospheric emission.


title: Low mass X-ray binaries as a stellar mass indicator for the host galaxy

abstract:
  Using results of Chandra observations of old stellar systems in eleven nearby
galaxies of various morphological types and the census of LMXBs in the Milky
Way, we study the population of low mass X-ray binaries and their relation to
the mass of the host galaxy. We show that the azimuthally averaged spatial
distribution of the number of LMXBs and, in the majority of cases, of their
collective luminosity closely follows that of the near-infrared light.
Considering galaxies as a whole, we find that in a broad mass range,
log(M)~9-11.5, the total number of LMXBs and their combined luminosity are
proportional to the stellar mass of the host galaxy. Within the accuracy of the
light-to-mass conversion, we cannot rule out the possibility of a weak
dependence of the X/M ratio on morphological type. However, the effect of such
a dependence, if any, does not exceed a factor of ~1.5-2.
  The luminosity distributions of LMXBs observed in different galaxies are
similar to each other and, with the possible exception of NGC1553, are
consistent with the average luminosity function derived from all data. The
average XLF of LMXBs in nearby galaxies has a complex shape and is
significantly different from that of HMXBs. It follows a power law with a
differential slope of ~1 at low luminosities, gradually steepens at
log(Lx)>37.0-37.5 and has a rather abrupt cut-off at log(Lx)~39.0-39.5. This
value of the cut-off luminosity is significantly, by an order of magnitude,
lower than found for high mass X-ray binaries.


title: HETE-2 Observations of the Extremely Soft X-Ray Flash XRF 020903

abstract:
  We report HETE-2 WXM/FREGATE observations of the X-ray flash, XRF 020903.
This event was extremely soft: the ratio log(S_X/S_gamma) = 0.7, where S_X and
S_gamma are the fluences in the 2-30 and 30-400 keV energy bands, is the most
extreme value observed so far by HETE-2. In addition, the spectrum has an
observed peak energy E^{obs}_{peak} < 5.0 keV (99.7 % probability upper limit)
and no photons were detected above ~10 keV. The burst is shorter at higher
energies, which is similar to the behavior of long GRBs. We consider the
possibility that the burst lies at very high redshift and that the low value of
E^{obs}_{peak} is due to the cosmological redshift, and show that this is very
unlikely. We find that the properties of XRF 020903 are consistent with the
relation between the fluences S(7-30 keV) and S(30-400 keV) found by Barraud et
al. for GRBs and X-ray-rich GRBs, and are consistent with the extension by a
decade of the hardness-intensity correlation (Mallozzi et al. 1995) found by
the same authors. Assuming that XRF 020903 lies at a redshift z = 0.25 as
implied by the host galaxy of the candidate optical and radio afterglows of
this burst, we find that the properties of XRF 020903 are consistent with an
extension by a factor ~300 of the relation between the isotropic-equivalent
energy E_iso and the peak E_peak of the nu F_nu spectrum (in the source frame
of the burst) found by Amati et al. for GRBs. The results presented in this
paper therefore provide evidence that XRFs, X-ray-rich GRBs, and GRBs form a
continuum and are a single phenomenon. The results also impose strong
constraints on models of XRFs and X-ray-rich GRBs.


title: A Unified Jet Model of X-Ray Flashes and Gamma-Ray Bursts

abstract:
  HETE-2 has provided strong evidence that the properties of X-Ray Flashes
(XRFs) and GRBs form a continuum, and therefore that these two types of bursts
are the same phenomenon. We show that both the structured jet and the uniform
jet models can explain the observed properties of GRBs reasonably well.
However, if one tries to account for the properties of both XRFs and GRBs in a
unified picture, the uniform jet model works reasonably well while the
structured jet model does not. The uniform jet model of XRFs and GRBs implies
that most GRBs have very small jet opening angles (~ half a degree). This
suggests that magnetic fields play a crucial role in GRB jets. The model also
implies that the energy radiated in gamma rays is ~100 times smaller than has
been thought. Most importantly, the model implies that there are ~10^4 -10^5
more bursts with very small jet opening angles for every such burst we see.
Thus the rate of GRBs could be comparable to the rate of Type Ic core collapse
supernovae. Determination of the spectral parameters and redshifts of many more
XRFs will be required in order to confirm or rule out the uniform jet model and
its implications. HETE-2 is ideally suited to do this (it has localized 16 XRFs
in ~2 years), whereas Swift is less so. The unique insights into the structure
of GRBs jets, the rate of GRBs, and the nature of Type Ic supernovae that XRFs
may provide therefore constitute a compelling scientific case for continuing
HETE-2 during the Swift mission.


title:
Search for Global Dipole Enhancements in the HiRes-I Monocular Data
  above 10^{18.5} eV

abstract:
  Several proposed source models for Ultra-High Energy Cosmic Rays (UHECRs)
consist of dipole distributions oriented towards major astrophysical landmarks
such as the galactic center, M87, or Centaurus A. We use a comparison between
real data and simulated data to show that the HiRes-I monocular data for
energies above 10^{18.5} eV is, in fact, consistent with an isotropic source
model. We then explore methods to quantify our sensitivity to dipole source
models oriented towards the Galactic Center, M87, and Centaurus A.


title:
A Model for High Frequency Quasi-periodic Oscillations from Accreting
  Black Holes

abstract:
  Observations from the Rossi X-Ray Timing Explorer have shown the existence of
high frequency quasi-periodic oscillations (HFQPOs) in the X-ray flux from
accreting black hole binary systems. In at least two systems, these HFQPOs come
in pairs with a 2:3 frequency commensurability. We propose a simple ``hot
spot'' model to explain the position and amplitude of the HFQPO peaks. Using
the exact geodesic equations for the Kerr metric, we calculate the trajectories
of massive test particles, which are treated as isotropic, monochromatic
emitters in their rest frames. Photons are traced from the accretion disk to a
distant observer to produce time- and frequency-dependent images of the
orbiting hot spot and background disk. The power spectrum of the X-ray light
curve consists of multiple peaks at integral combinations of the black hole
coordinate frequencies. In particular, if the radial frequency is one-third of
the azimuthal frequency (as is the case near the inner-most stable circular
orbit), beat frequencies appear in the power spectrum at two-thirds and
four-thirds of the fundamental azimuthal orbital frequency, in agreement with
observations. We also model the effects of shearing the hot spot in the disk,
producing an arc of emission that also follows a geodesic orbit, as well as the
effects of non-planar orbits that experience Lens-Thirring precession around
the black hole axis. By varying the arc length, we are able to explain the
different QPO features observed in ``Type A'' and ``Type B'' X-ray outbursts
from XTE J1550-564. In the context of this model, the observed power spectra
allow us to infer values for the black hole mass and angular momentum, and also
constrain the parameters of the model, such as the hot spot size and
luminosity.


title: Astrometry of the OH masers of 4 Mira stars

abstract:
  The OH main line masers in circumstellar shells were observed with
astrometric VLBI in order to accurately determine the position of the star, as
well as its motion, including the parallax. Results are presented on 4 Mira
stars monitored for 2 - 8 years with the VLBA. The data show that in some stars
the VLBI detection is dominated by blue-shifted emission that is associated
with the stellar image amplified by the maser shell in front of the star. In
other cases the maser is not directly tied to the stellar position, but still
persistent enough to measure proper motion and parallax.


title: The Nature of E+A Galaxies in Intermediate Redshift Clusters

abstract:
  [Abridged] Combining HST/WFPC2 mosaics with extensive ground-based
spectroscopy, we study the nature of E+A galaxies in three intermediate
redshift clusters (z=0.33, 0.58, & 0.83). From a sample of ~500 confirmed
cluster members, we isolate 46 E+A candidates to determine the E+A fraction and
study their physical properties. We find E+A's comprise a non-negligible
component (~7-13%) of the cluster population at these redshifts, and their
diverse nature indicates a heterogeneous parent population. Cluster E+A's span
the range in Hubble type and cover a wide range in luminosity, internal
velocity dispersion, and half-light radius. From their velocity dispersions and
half-light radii, we infer that the descendants of E+A's in our highest
redshift cluster are massive early-type galaxies. We find a decrease in the
characteristic E+A mass similar to the decrease in luminosity of rapidly
star-forming field galaxies since z~1, i.e. galaxy ``down-sizing.'' In
addition, we argue our statistics imply that >30% of the E-S0 members have
undergone an E+A phase; the true fraction could be 100% if the effects of E+A
down-sizing, an increasing E+A fraction with redshift, and the conversion of
spirals into early-types are also considered. Thus, the E+A phase may indeed be
an important stage in the transformation of star-forming galaxies into
early-type cluster members.


title: Theoretical Examination of the Lithium Depletion Boundary

abstract:
  We explore the sensitivity in open cluster ages obtained by the lithium
depletion boundary (LDB) technique to the stellar model input physics. The LDB
age technique is limited to open clusters with ages ranging from 20 to 200 Myr.
Effective 1-sig errors in the LDB technique due to uncertain input physics are
roughly 3% at the oldest age increasing to 8% at the youngest age. Bolometric
correction uncertainties add an additional 10 to 6% error to the LDB age
technique for old and young clusters, respectively. Rotation rates matching the
observed fastest rotators in the Pleiades affect LDB ages by less than 2%. The
range of rotation rates in an open cluster are expected to ``smear'' the LDB
location by only 0.02 mag for a Pleiades age cluster increasing to 0.06 mag for
a 20 Myr cluster. Thus, the observational error of locating the LDB (~7-10%)
and the bolometric correction uncertainty currently dominate the error in LDB
ages. For our base case, we formally derive a LDB age of 148 +- 19 Myr for the
Pleiades, where the error includes 8, 3, and 9% contributions from
observational, theoretical, and bolometric correction sources, respectively. A
maximally plausible 0.3 magnitude shift in the I-band bolometric correction to
reconcile main sequence isochrone fits with the observed (V-I) color for the
low mass Pleiades members results in an age of 126 +- 11 Myr, where the error
includes observational and theoretical errors only. Upper main-sequence-fitting
ages that do not include convective core overshoot for the Pleiades (~75 Myr)
are ruled out by the LDB age technique.


title: Scientific Highlights of the HETE-2 Mission

abstract:
  The HETE-2 mission has been highly productive. It has observed more than 250
GRBs so far. It is currently localizing 25 - 30 GRBs per year, and has
localized 43 GRBs to date. Twenty-one of these localizations have led to the
detection of X-ray, optical, or radio afterglows, and as of now, 11 of the
bursts with afterglows have known redshifts. HETE-2 has confirmed the
connection between GRBs and Type Ic supernovae, a singular achievement and
certainly one of the scientific highlights of the mission so far. It has
provided evidence that the isotropic-equivalent energies and luminosities of
GRBs are correlated with redshift, implying that GRBs and their progenitors
evolve strongly with redshift. Both of these results have profound implications
for the nature of GRB progenitors and for the use of GRBs as a probe of
cosmology and the early universe. HETE-2 has placed severe constraints on any
X-ray or optical afterglow of a short GRB. It is also solving the mystery of
"optically dark' GRBs, and revealing the nature of X-ray flashes.


title: Gamma-Ray Bursts as a Laboratory for the Study of Type Ic Supernovae

abstract:
  HETE-2 has confirmed the connection between GRBs and Type Ic supernovae. Thus
we now know that the progenitors of long GRBs are massive stars. HETE-2 has
also provided strong evidence that the properties of X-Ray Flashes (XRFs) and
GRBs form a continuum, and therefore that these two types of bursts are the
same phenomenon. We show that both the structured jet and the uniform jet
models can explain the observed properties of GRBs reasonably well. However, if
one tries to account for the properties of both XRFs and GRBs in a unified
picture, the uniform jet model works reasonably well while the structured jet
model fails utterly. The uniform jet model of XRFs and GRBs implies that most
GRBs have very small jet opening angles (~ half a degree). This suggests that
magnetic fields play a crucial role in GRB jets. The model also implies that
the energy radiated in gamma rays is ~100 times smaller than has been thought.
Most importantly, the model implies that there are ~10^4 -10^5 more bursts with
very small jet opening angles for every such burst we see. Thus the rate of
GRBs could be comparable to the rate of Type Ic core collapse supernovae.
Accurate, rapid localizations of many XRFs, leading to identification of their
X-ray and optical afterglows and the determination of their redshifts, will be
required in order to confirm or rule out these profound implications. HETE-2 is
ideally suited to do this (it has localized 16 XRFs in ~2 years), whereas Swift
is not. The unique insights into the structure of GRB jets, the rate of GRBs,
and the nature of Type Ic supernovae that XRFs may provide therefore constitute
a compelling scientific case for continuing HETE-2 during the Swift mission.


title:
The observability of gamma-rays from neutralino annihilations in Milky
  Way substructure

abstract:
  We estimate the probability of detecting gamma-rays from the annihilation of
neutralino dark matter in dense, central regions of Milky Way substructure. We
characterize Galactic substructure statistically based on Monte Carlo
realizations of the formation of a Milky Way-like halo using a semi-analytic
method that has been calibrated against the results of high-resolution N-body
simulations. We find that it may be possible for the upcoming experiments GLAST
and VERITAS, working in concert, to detect gamma-rays from dark matter
substructure if the neutralino is relatively light ($\Mchi \lsim 100 \GeV$),
while for $\Mchi \gsim 500 \GeV$ such a detection would be unlikely. We perform
most of our calculations within the framework of the standard $\Lambda$CDM
cosmological model; however, we also investigate the robustness of our results
to various assumptions and find that the probability of detection is sensitive
to poorly-constrained input parameters, particularly those that characterize
the primordial power spectrum. Specifically, the best-fitting power spectrum of
the WMAP team, with a running spectral index, predicts roughly a factor of
fifty fewer detectable subhalos compared to the standard $\LCDM$ cosmological
model with scale-invariant power spectrum. We conclude that the lack of a
detected gamma-ray signal gives very little information about the
supersymmetric parameter space due to uncertainties associated with both the
properties of substructure and cosmological parameters.


title:
The Dark Matter Distribution in the Central Regions of Galaxy Clusters:
  Implications for CDM

abstract:
  We have undertaken a spectroscopic survey of gravitational arcs in a
carefully chosen sample of six clusters each containing a dominant brightest
cluster galaxy. We use these systems to study the relative distributions of
dark and baryonic material in the central regions. Three clusters present both
radial and tangential arcs and provide particularly strong constraints on the
mass profiles, whereas the other three display only tangential arcs and act as
a control set. We analyze stellar velocity dispersion data for the brightest
cluster galaxies in conjunction with the arc redshifts and lens models to
constrain the dark and baryonic mass profiles jointly. For the systems
containing radial arcs we find that the inner dark matter density profile is
consistent with a 3-D distribution, rho_{DM} propto r^-beta, with logarithmic
slope <beta>=0.52^{+0.05}_{-0.05} (68% CL). Similarly, we find that the
tangential arc sample gives an upper limit, beta<0.57 (99% CL). Taking the 6
clusters together, the mean dark matter distribution is quite inconsistent with
the standard Navarro, Frenk & White (1997) value, beta=1.0, at >99% confidence.
In addition, we find considerable cosmic scatter in the beta (Delta beta ~0.3)
values of the radial arc sample. We find no evidence that systems with radial
arcs preferentially yield flatter dark matter profiles as might be expected if
they were a biased subset. We discuss the validity of our 1-D mass
reconstruction method and verify its conclusions by comparing with results of a
more rigorous ray-tracing lensing code. Our results extend and strengthen the
earlier conclusions presented by Sand et al. (2002) and suggest the
relationship between dark and visible matter in the cores of clusters is more
complex than anticipated from recent simulations. (abridged)


title: First Starbursts at high redshift: Formation of globular clusters

abstract:
  Numerical simulations of a Milky Way-size galaxy demonstrate that globular
clusters with the properties similar to observed can form naturally at z > 3 in
the concordance Lambda-CDM cosmology. The clusters in our model form in the
strongly baryon-dominated cores of supergiant molecular clouds. The first
clusters form at z = 12, while the peak formation appears to be at z = 3-5. The
zero-age mass function of globular clusters can be approximated by a power-law
dN/dM ~ M^-2, in agreement with observations of young massive star clusters.


title:
Comparing Chandra and SIRTF Observations for Obscured Starbursts and AGN
  at High Redshift

abstract:
  Tracking the star formation rate to high redshifts requires knowledge of the
contribution from both optically visible and obscured sources. The dusty,
optically-obscured galaxies can be located by X-ray and infrared surveys. To
establish criteria for selecting such sources based only on X-ray and infrared
surveys, we determine the ratio of infrared to X-ray brightness that would be
observed by SIRTF and Chandra for objects with the same spectral shapes as
nearby starbursts if seen at high redshift. The parameter IR/X is defined as
IR/X = (flux density observed in SIRTF MIPS 24 $\mu$m filter in mJy)/(total
flux observed within 0.5-2.0 keV in units of 10^-16 ergs\s\cm^2). Based on
observations of NGC 4038/39 (``The Antennae''), NGC 3690+IC 694 (Arp 299 or Mkn
171), M 82, and Arp 220, nine starburst regions are compared using mid-infrared
spectra taken by the Infrared Space Observatory (ISO) and X-ray spectra
obtained with Chandra . The IR/X are determined as they would appear for 1<z<3.
The mean IR/X over this redshift range is 1.3 and is not a significant function
of redshift or luminosity, indicating that SIRTF surveys reaching 0.4 mJy at 24
$\mu$m should detect the same starbursts as deep CXO surveys detect at a flux
of 0.3x10^-16 ergs/s/cm^2. The lower bound of IR/X for starbursts is about 0.2,
suggesting that objects with IR/X smaller than this have an AGN X-ray component
in addition to the starburst. Values of IR/X for the obscured AGN within NGC
1068, the Circinus galaxy, and NGC 6240 are also determined for comparison
although interpretation is complicated by the circumnuclear starbursts in these
galaxies. Any sources found in surveys having IR/X>4 would not match any of the
objects considered.


title:
Gemini-South + FLAMINGOS Demonstration Science: Near-Infrared
  Spectroscopy of the z=5.77 Quasar SDSS J083643.85+005453.3

abstract:
  We report an infrared 1-1.8 micron (J+H-bands), low-resolution (R=450)
spectrogram of the highest-redshift radio-loud quasar currently known, SDSS
J083643.85+005453.3, obtained during the spectroscopic commissioning run of the
FLAMINGOS multi-object, near-infrared spectrograph at the 8m Gemini-South
Observatory. These data show broad emission from both CIV 1549 and CIII] 1909,
with strengths comparable to lower-redshift quasar composite spectra. The
implication is that there is substantial enrichment of the quasar environment,
even at times less than a billion years after the Big Bang. The redshift
derived from these features is z = 5.774 +/- 0.003, more accurate and slightly
lower than the z = 5.82 reported in the discovery paper based on the
partially-absorbed Lyman-alpha emission line. The infrared continuum is
significantly redder than lower-redshift quasar composites. Fitting the
spectrum from 1.0 to 1.7 microns with a power law f(nu) ~ nu^(-alpha), the
derived power law index is alpha = 1.55 compared to the average continuum
spectral index <alpha> = 0.44 derived from the first SDSS composite quasar.
Assuming an SMC-like extinction curve, we infer a color excess of E(B-V) = 0.09
+/- 0.01 at the quasar redshift. Only approximately 6% of quasars in the
optically-selected Sloan Digital Sky Survey show comparable levels of dust
reddening.


title: Radio Loud AGN in the Context of the Eigenvector 1 Parameter Space

abstract:
  We consider the properties of radio-loud (RL) AGN in the context of the
Eigenvector 1 (E1) parameter space. RL sources show a restricted E1 parameter
space occupation relative to the radio-quiet (RQ) majority. The Fanaroff-Riley
II ``parent population'' of relatively un-boosted RL sources (median
radio/optical flux ratio ~490) shows the most restricted occupation. RL sources
have different broad line properties (and inferred black hole masses and
Eddington ratios). FWHM H_beta for the broad line component in RL sources are
at least twice as large as the RQ majority. The average broad FeII emission
line strength is also about half that for RQ sources. Our sample suggests that
the RL cutoff occurs near R_k=70 or logP(6cm)=32.0 ergs/s/Hz. Sources below
this cutoff are RQ although we cannot rule out the existence of a distinct
intermediate population. We show that the Doppler boosted core-dominated RL
sources (median flux ratio ~1000) lie towards smaller FWHM(H_beta_bc) and
stronger FeII in E1 as expected if the lines arise in an accretion disk. Our
subsample of superluminal sources, with orientation inferred from the
synchrotron self Compton model, reinforce this general E1 trend and allow us to
estimate the role of source orientation in driving E1 domain occupation.


title:
Observational Tests of Damping by Resonant Absorption in Coronal Loop
  Oscillations

abstract:
  One of the proposed damping mechanisms of coronal (transverse) loop
oscillations in the kink-mode is resonant absorption as a result of the Alfven
speed variation at the outer boundary of coronal loops. Analytical expressions
for the period and damping time exist for loop models with thin non-uniform
boundaries. Here we measure the thickness of the non-uniform layer in
oscillating loops for 11 events, by forward-fitting of the cross-sectional
density profile and line-of-sight integration to the cross-sectional fluxes
observed with TRACE 171 A. This way we model the internal and external electron
density of the coronal plasma in oscillating loops. This allows us to test the
theoretically predicted damping rates for thin boundaries as function of the
density ratio. We find that the density ratio predicted by the damping time is
higher than the density ratio estimated from the background fluxes. The lower
densities modeled from the background fluxes are likely to be a consequence of
the neglected hotter plasma that is not detected with the TRACE 171 A filter.
Taking these correction into account, resonant absorption predicts damping
times of kink-mode oscillations that are commensurable with the observed ones
and provides a new diagnostic of the density contrast of oscillating loops.


title: Starburst Galaxies: Why the Calzetti Dust Extinction Law?

abstract:
  The empirical reddening function for starburst galaxies generated by Calzetti
and her co-workers has proven very successful, and is now used widely in the
observational literature. Despite its success, however, the physical basis for
this extinction law, or more correctly, attenuation law remains weak. Here we
provide a physical explanation for the Calzetti Law based on a turbulent
interstellar medium. In essence, this provides a log-normal distribution of
column densities, giving a wide range of column densities in the dusty
foreground screen. Therefore, extended sources such as starburst regions or HII
regions seen through it suffer a point-to-point stochastic extinction and
reddening. Regions of high column densities are "black" in the UV, but
translucent in the IR, which leads to a flatter extinction law, and a larger
value of the total to selective extinction, R_V. We fit the Calzetti Law, and
infer that the variance sigma of the log-normal distribution lies in the range
0.6<sigma<2.2. The absolute to selective extinction R_V is found to be in the
range 4.3 to 5.2 consistent with R_V=4.05+/-0.80 of the Calzetti Law.


title: Strange Stars with a Density-Dependent Bag Parameter

abstract:
  We have studied strange quark stars in the framework of the MIT bag model,
allowing the bag parameter B to depend on the density of the medium. We have
also studied the effect of Cooper pairing among quarks, on the stellar
structure. Comparison of these two effects shows that the former is generally
more significant. We studied the resulting equation of state of the quark
matter, stellar mass-radius relation, mass-central-density relation,
radius-central-density relation, and the variation of the density as a function
of the distance from the centre of the star. We found that the
density-dependent B allows stars with larger masses and radii, due to
stiffening of the equation of state. Interestingly, certain stellar
configurations are found to be possible only if B depends on the density. We
have also studied the effect of variation of the superconducting gap parameter
on our results.


title:
Infrared emission towards 11 years after outburst: Properties of the
  circumstellar dust

abstract:
  Detailed models are presented for the late epoch mid infrared (MIR) emission
from collisionally heated grains in the shocked circumstellar gas around SN
1987A. Thermal dust emission from a region of moderate density interior to the
thick inner ring seen with the Hubble Space Telescope (HST) is found to be a
natural explanation for the MIR spectral energy distribution measured by
ISOCAM. The MIR-spectrum can be reproduced by a mixture of silicate-iron or
silicate-graphite grains or by a composition of pure graphite grains. A
composition of pure iron grains on the other hand can be excluded and a pure
silicate composition does not seem to be very likely. The dust-to-gas ratio in
the interaction zone is ~0.01%, an order of magnitude lower than estimates for
dust abundances in the winds of red supergiant (RSG) stars in the LMC. This low
dust abundance can be accounted for by a combination of evaporation through the
UV-flash from the supernova outburst and subsequent sputtering in the shocked
gas. For this explanation to hold, dust in the pre-supernova circumstellar
medium (CSM) would have to have been predominantly composed of grains other
than graphite, with a maximum size smaller than ~0.1 microns.


title: Non-Abelian Effects in Gravitation

abstract:
  The non-abelian symmetry of a lagrangian invalidates the principle of
superposition for the field described by this lagrangian. A consequence in QCD
is that non-linear effects occur, resulting in the quark-quark linear potential
that explains the quark confinement, the quarkonia spectra or the Regge
trajectories. Following a parallel between QCD and gravitation, we suggest that
these non-linear effects should create an additional logarithmic potential in
the classical newtonian description of gravity. The modified potential may
account for the rotation curve of galaxies and other problems, without
requiring dark matter.


title:
Infrared emission towards SN 1987A 11 years after outburst: Measurements
  with ISOCAM

abstract:
  We present measurements of the mid-infrared (MIR) emission from SN 1987A,
made using the Infrared Space Observatory (ISO) 11 years after outburst. They
are the only late epoch detections of this source in the thermal IR regime. The
position of the source, determined from an offset to an IR-emitting star,
suggests that the emission is associated with SN 1987A or its extended
supernova remnant (SNR). A predominantly circumstellar origin is however
suggested by the size and orientation of the IR-emitting region, which is
comparable with the extension of the inner ring seen with the Hubble Space
Telescope (HST). The emission is most probably from collisionally-heated
circumstellar grains embedded in shocked gas downstream of the blast wave. The
MIR extent is consistent with the hypothesis that the blast wave was
propagating into material of moderate density interior to the thick inner ring
at the epoch of the ISOCAM observations.


title:
Giant Planets and Variable Stars in 47 Tucanae - a progress report of a
  comprehensive ground-based search

abstract:
  We present a short progress report of a comprehensive search for variability
in the globular cluster 47 Tucanae. Using the MSSSO 40'' telescope and a
combined V+R filter, we are searching for variability across a 52x52' field
centered on the cluster. The main aim is to search for transiting 'Hot Jupiter'
planets, the results of which are still being produced, but a natural side
product is a deep catalogue of variable stars within the cluster field. The
experiment samples the whole of the cluster (except the inner 5'), thus probing
the uncrowded outer regions where the stellar densities are lower, increasing
the prospects for the survivability of planetary systems. Half of the currently
identified variable stars are new discoveries. We have data for 36,000 stars
with masses similar to that of the Sun for the main transit search.


title: HI on large and small scales in starburst radio galaxies

abstract:
  The study of the optical continuum of radio galaxies shows that about 30%
have a young stellar population component. Among them are the most far-IR
bright radio galaxies. A further indication of the relatively gas rich
environment of these galaxies (possibly related to the recent merger from which
they originate) is the high fraction being detected in HI. Here we present
recent results obtained from the study of neutral hydrogen (detected either in
emission or absorption) in a group of starburst radio galaxies. In some
objects, large-scale (tens of kpc) structures involving HI masses exceeding
10^9 M_sun are observed. In these cases, the HI can be used to study the origin
and evolution of these systems and the timescales involved. In this respect,
the parameters obtained from the study of the stellar populations and from the
HI can be complementary. In other objects, very broad (> 1000 km/s), mostly
blueshifted HI is detected in absorption. This result shows that, despite the
extremely energetic phenomena occurring near an AGN - including the powerful
radio jet - some of the outflowing gas remains, or becomes again, neutral. This
can give new and important insights in the physical conditions of the gaseous
medium around an AGN. The possible origin of the extreme kinematics is
discussed.


title: Quantum Gravity and the Big Bang

abstract:
  Quantum gravity has matured over the last decade to a theory which can tell
in a precise and explicit way how cosmological singularities of general
relativity are removed. A branch of the universe "before" the classical big
bang is obtained which is connected to ours by quantum evolution through a
region around the singularity where the classical space-time dissolves. We
discuss the basic mechanism as well as applications ranging to new
phenomenological scenarios of the early universe expansion, such as an
inflationary period.


title: Recovery of the old nova V840 Ophiuchi: A carbon rich system

abstract:
  We present optical spectroscopy and multi colour photometry of the old nova
V840 Oph. We rediscovered the nova based on its position in the colour--colour
diagrams. It stands out as a very blue object with an additional red component.
We present the first optical spectroscopy of this candidate and confirm its
nova character. Furthermore, V840\,Oph has been found as one of very few
cataclysmic variables showing C IV emission at lambda = 580/1 nm. From the
analysis of the carbon lines it seems probable that V840 Oph contains actually
a carbon-rich secondary star. So far, only the nova-like QU Car has been known
to have such a companion. We furthermore find spectroscopic evidence that V840
Oph has a hot, dense accretion disc or stream and is probably a magnetic
system.


title:
Updated Big Bang Nucleosynthesis confronted to WMAP observations and to
  the Abundance of Light Elements

abstract:
  We improve Standard Big Bang Nucleosynthesis (SBBN) calculations taking into
account new nuclear physics analyses (Descouvemont et al. 2003). Using a
Monte-Carlo technique, we calculate the abundances of light nuclei versus the
baryon to photon ratio.The results concerning omegab are compared to relevant
astrophysical and cosmological observations. Consistency between WMAP, SBBN
results and D/H data strengthens the deduced baryon density and has interesting
consequences on cosmic chemical evolution. A significant discrepancy between
the calculated Li-7 deduced from WMAP and the Spite plateau is clearly
revealed. To explain this discrepancy three possibilities are invoked :
uncertainties on the Li abundance, surface alteration of Li in the course of
stellar evolution or poor knowledge of the reaction rates related to Be-7
destruction. In particular, the possible role of the up to now neglected
Be-7(d,p)2He-4 and Be-7(d,alpha)Li5 reactions is considered. The impressive
advances in CMB observations provide a strong motivation for more efforts in
experimental nuclear physics and high quality spectroscopy to keep BBN in pace.


title: T Tauri Multiple Systems

abstract:
  New high-resolution adaptive optics systems provide an unprecedentedly
detailed view of nearby star forming regions. In particular, young nearby T
Tauri stars can be probed at much smaller physical scales (a few AU) than
possible just a decade ago (several tens of AU). Of major importance is closing
the sensitivity gap between imaging and spectral surveys for stellar
companions. This allows for 1) calibration of pre-main-sequence evolutionary
tracks by obtaining accurate dynamical masses, 2) resolving confusion problems
arising by placing unresolved systems in colour-magnitude diagrams, and 3) well
defined and determined multiplicity fractions of young stellar systems,
important for discriminating star formation scenarios. This article briefly
reviews the current status of high resolution imaging of T Tauri multiple
systems, and what we can expect to learn from them in the near future.


title: Cosmological Parameters from Cosmic Shear

abstract:
  We present simulations of a cosmic shear survey and show how the survey
geometry influences the accuracy of determination of cosmological parameters.
We numerically calculate the full covariance matrices of the two-point
statistics \xi_+, \xi_- and <Map^2> and use maximum likelihood and Fisher
matrix analyses in order to derive expected constraints on the cosmological
parameters \Omega_m, \sigma_8, \Gamma, n_s and \Omega_\Lambda.


title:
On the Purity of the ZZ Ceti Instability Strip: Discovery of More
  Pulsating DA White Dwarfs on the Basis of Optical Spectroscopy

abstract:
  We report the discovery of two new ZZ Ceti pulsators, LP 133-144 and HE
1258+0123, selected on the basis of model atmosphere fits to optical
spectroscopic data. The atmospheric parameters for LP 133-144, Teff = 11,800
+/- 200 K and log g = 7.87 +/- 0.05, and for HE 1258+0123, Teff = 11,410 +/-
200 K and log g = 8.04 +/- 0.05, place them within the empirical boundaries of
the ZZ Ceti instability strip. This brings the number of known ZZ Ceti stars to
a total of 36, a quarter of which have now been discovered using the
spectroscopic approach for estimating their atmospheric parameters. This method
has had a 100% success rate so far in predicting the variability of candidate
ZZ Ceti stars. We have also analyzed additional spectra of known nonvariable
white dwarfs in the vicinity of the ZZ Ceti instability strip. Our study
further strengthens the idea that ZZ Ceti stars occupy a pure region in the log
g-Teff plane, a region where no nonvariable stars are found. This result
supports the thesis that ZZ Ceti pulsators represent a phase through which all
DA stars must evolve.


title:
Early SPI/INTEGRAL measurements of galactic 511 keV line emission from
  positron annihilation

abstract:
  We report the first measurements of the 511 keV line emission from the
Galactic Centre (GC) region performed with the spectrometer SPI on the space
observatory INTEGRAL (International Gamma-Ray Astrophysics Laboratory). Taking
into account the range of spatial distribution models which are consistent with
the data, we derive a flux of $9.9^{+4.7}_{-2.1} \times 10^{-4}$ ph cm$^{-2}$
s$^{-1}$ and an intrinsic line width of $2.95^{+0.45}_{-0.51}$ keV (FWHM). The
results are consistent with other high-spectroscopy measurements, though the
width is found to be at the upper bound of previously reported values.


title: Cluster mass functions in the quintessential Universe

abstract:
  We use $N$-body simulations to measure mass functions in flat cosmological
models with quintessence characterized by constant $w$ with $w=-1$, -2/3 and
-1/2. The results are compared to the predictions of the formula proposed by
Jenkins et al. at different redshifts, in terms of FOF masses as well as Abell
masses appropriate for direct comparison to observations. The formula
reproduces quite well the mass functions of simulated haloes in models with
quintessence. We use the cluster mass function data at a number of redshifts
from Carlberg et al. to constrain $\Omega_0$, $\sigma_8$ and $w$. The best fit
is obtained in the limit $w \to 0$, but none of the values of $w$ in the
considered range $-1 \le w < 0$ can actually be excluded. However, the adopted
value of $w$ affects significantly the constraints in the $\Omega_0-\sigma_8$
plane. Taking into account the dependence on $w$ we find $\Omega_0=0.32 \pm
0.15$ and $\sigma_8=0.85_{-0.12}^{+0.38}$ (68% c.l.). Since less negative $w$
push the confidence regions toward higher $\Omega_0$ and lower $\sigma_8$ we
conclude that relaxing the assumption of $w=-1$ typically made in such
comparisons may resolve the discrepancy between recent cluster mass function
results (yielding rather low $\Omega_0$ and high $\sigma_8$) and most other
estimates. The fact that high $w$ values are preferred may however also point
towards some unknown systematics in the data or the model with constant $w$
being inadequate.


title: Stability and evolution of super-massive stars (SMS)

abstract:
  Highly condensed gaseous objects with masses larger than 5x10^4 M_sun are
called super-massive stars. In the quasistationary contraction phase, the
hydrostatic equilibrium is determined by radiation pressure and gravitation.
The global structure is that of an n=3 polytrope at the stability limit. Small
relativistic corrections for example can initiate a free fall collapse due to
the 'post Newtonian' instability. Since the outcome of the final collapse -A
super-massive black hole or hypernova- depends sensitively on the structure and
the size of the object, when the instability sets in, it is important to
investigate in more detail the contraction phase of the SMS. If the gaseous
object is embedded in a dense stellar system, the central star cluster, the
interaction and coupling of both components due to dynamical friction changes
the energy balance and evolution of the SMS dramatically. Dynamical friction
between stars and gas, which can be estimated semi-analytically (see Just et
al. 1986), has three different effects on the two-component system. We discuss
in which evolutionary stages and parameter range these interaction processes
are relevant and how they can influence the stability and evolution of the SMS.


title:
The effect of the electron donor H3+ on the pre-main and Main Sequence
  evolution of low mass zero metallicity stars

abstract:
  H3+ has been shown (Lenzuni et al. 1991, ApJS, 76, 759) to be the dominant
positive ion, in a zero metallicity gas at low temperature and intermediate to
high density. It therefore affects both the number of free electrons and the
opacity of the gas. The most recent H3+ partition function (Neale and Tennyson,
1995, ApJ, 454, L169) is an order of magnitude larger at 4000 K than all
previous partition functions, implying that H3+ is a more important electron
donor than previously thought.
  Here we present new Rosseland mean opacities for a hydrogen-helium gas of
1000 < T(K) < 9000 and -14 < log10(density [g/cc]) < -2. In the calculation of
these opacities we have made use of the latest collision induced absorption
data as well as the most recent H3+ partition function and line opacity data.
It is shown that these updated and new sources of opacity give rise to a
Rosseland mean opacity for a hydrogen-helium gas which is in general greater
than that calculated in earlier works.
  The new opacity data are then used to model the evolution of low mass
0.15-0.8 Mo zero metallicity stars, from pre-Main Sequence collapse to Main
Sequence turn-off. To investigate the effect of H3+ on the evolution of low
mass zero metallicity stars, we repeat our calculations neglecting H3+ as a
source of electrons and line opacity. We find that H3+ can have an effect on
the structure and evolution of stars of mass ~0.5 Mo or less. A gray atmosphere
is used for the calculation, which is sufficient to demonstrate that H3+
affects the evolution of very low mass stars to a greater degree than
previously believed.


title:
Dynamical friction on Globular Clusters in core-triaxial galaxies: is it
  a cause of massive black hole accretion?

abstract:
  The present work extends and deepens previous examinations of the evolution
of globular cluster orbits in elliptical galaxies, by means of numerical
integrations of a wide set of orbits in 5 self-consistent triaxial galactic
models characterized by a central core and different axial ratios. These models
constitute a valid and complete representation of regular orbits in elliptical
galaxies. Dynamical friction is definitely shown to be an efficient cause of
evolution for the globular cluster systems in elliptical galaxies of any mass
and axial ratios. Moreover, our statistically significant sample of computed
orbits confirm that the globular cluster orbital decay times are, in a wide
range of realistic initial conditions, much shorter than the age of the
galaxies. Consequently, the huge quantity of mass carried into the innermost
galactic region in form of decayed globular clusters have likely contributed
significantly in feeding and accreting a compact object therein.


title: Testing the Paradigm of Low-Mass Star Formation

abstract:
  Protostellar core formation is probably much more dynamic, and magnetic
fields are probably much less important, than has been previously assumed in
the standard model of low-mass star formation. This revised picture has
important consequences: it is easier to understand the observed rapidity of
star formation in molecular clouds; cores are more likely to have structures
favoring high infall rates at early times, helping to explain the differences
between Class 0 and Class I protostars; and core structure and asymmetry will
strongly favor post-collapse fragmentation into binary and multiple stellar
systems.


title:
The GraS Hypothesis: a Model for Dark Matter-Baryons Gravitational
  Interaction

abstract:
  According to the gravitational suppression (GraS) hypothesis the
gravitational interaction between exotic (dark) and standard (visible) matter
is suppressed below the kpc scales. We review the phenomenological motivations
at the basis of this idea and its formal implementation by means of a Yukawa
contribution to the usual Newtonian potential. We also discuss a class of
astrophysical phenomena that may help in testing this scenario.


title: Signal Fluctuations in the Auger Surface Detector

abstract:
  We measured the Cerenkov signal fluctuations in the water tanks of the Pierre
Auger Observatory. Two stations located near the center of the 32-tank
Engineering Array separated by 11 m were used for the purpose. At this
separation the stations sample nearly the same region of the air shower.
Sources of the signal fluctuations are discussed.


title: z-ph-REM: A photometric redshift code for the REM telescope

abstract:
  The REM telescope is being deployed these very days at the La Silla
Observatory in Chile, and will be fully operational by the beginning of 2004.
It is a very fast-slewing robotized telescope, endowed with optical and
near-infrared capabilities, designed with the primary objective of performing
rapid follow-up of GRB events. One of the key issues will be the prompt
recognition of potentially interesting bursts (those happening at high redshift
or peculiarly reddened). Here I present a sketch of z-ph-REM, the photometric
redshift code designed for this mission.


title: MHD Sausage Mode Oscillations in Coronal Loops

abstract:
  A recent study by Nakariakov et al. pointed out that the dispersion relation
of MHD sausage mode oscillations has been incorrectly applied to coronal loops,
neglecting the highly dispersive nature of the phase speed and the
long-wavelength cutoff of the wave number. In the light of these new insights
we revisit previous observations that have been interpreted in terms of MHD
sausage mode oscillations in coronal loops and come to the following
conclusions: (1) Fast sausage MHD mode oscillations require such a high
electron density imposed by the wave number cutoff that they can only occur in
flare loops; (2) In the previously reported radio observations ($\nu \approx
100$ MHz to 1 GHz) with periods of $P\approx 0.5-5$ s, the fast sausage MHD
mode oscillation is likely to be confined to a small segment (corresponding to
a high harmonic node) near the apex of the loop, rather than involving a global
oscillation over the entire loop length. The recent microwave and soft X-ray
observations of fast periods ($P\approx 6-17$ s) by Asai et al. and Melnikov et
al., however, are consistent with fast sausage MHD oscillations at the
fundamental harmonic.


title: History of Star Formation Rate and Luminosity Density of Galaxies

abstract:
  We have computed the time evolution of bolometric, far-infrared, Halpha line,
ultraviolet (both intrinsic and escaping the star forming region) and the
nonthermal radio continuum luminosities for continuous and constant star
formation. The luminosity rises to a plateau value and declines after the
termination of starburst, but only gradually. The time evolution profiles are
broad and different for different star formation indicators. The broad profiles
lead to uncertainties in the star formation rate derived depending on the
initial mass function, duration of starburst, its distribution and the
observational epoch.


title:
The formation of cluster elliptical galaxies as revealed by extensive
  star formation

abstract:
  The most massive galaxies in the present-day Universe are found to lie in the
centres of rich clusters. They have old, coeval stellar populations suggesting
that the bulk of their stars must have formed at early epochs in spectacular
starbursts - luminous phenomena at submillimetre wavelengths. The most popular
model of galaxy formation predicts that these galaxies form in proto-clusters
at high-density peaks in the early Universe. Such peaks are signposted by
massive high-redshift radio galaxies. Here we report deep submillimetre mapping
of seven high-redshift radio galaxies and their environments. These data
confirm not only the presence of spatially extended massive star-formation
activity in the radio galaxies themselves, but also in companion objects
previously undetected at any wavelength. The prevalence, orientation, and
inferred masses of these submillimetre companion galaxies suggest that we are
witnessing the synchronous formation of the most luminous elliptical galaxies
found today at the centres of rich galaxy clusters.


title: Environmental Effects on the Kinematics of Virgo Cluster Galaxies

abstract:
  We present results from an ongoing survey dedicated to the ionized gas
kinematics of Virgo cluster spiral galaxies using Fabry-Perot interferometry.
Our goal is to study the environmental effects on galaxy evolution in the Virgo
cluster. We report here on the Halpha distribution map and velocity field of
NGC 4438, the prototype of an interacting galaxy near the centre of the
cluster.


title: Diffuse X-Rays from the Inner 3 Parsecs of the Galaxy

abstract:
  Recent observations with the Chandra X-ray Observatory have provided us with
the capability to discriminate point sources, such as the supermassive black
hole Sgr A*, from the diffuse emission within the inner 10'' of the Galaxy. The
hot plasma producing the diffuse X-radiation, estimated at ~7.6*10^{31} ergs
s^{-1} arcsec^{-2} in the 2-10 keV band, has a RMS electron density ~26 cm^{-3}
and a temperature kT ~= 1.3 keV, with a total inferred mass of ~0.1 solar
masses. At least some of this gas must be injected into the ISM via stellar
winds. In the most recent census, about 25 bright, young stars have been
identified as the dominant sources of the overall mass efflux from the Galactic
center. In this paper, we use detailed 3-dimensional SPH simulations to study
the wind-wind interactions occurring in the inner 3 parsecs of the Galaxy, with
a goal of understanding what fraction, if any, of the diffuse X-ray flux
measured by Chandra results from the ensuing shock heating of the ambient
medium. We conclude that this process alone can account for the entire X-ray
flux observed by Chandra in the inner 10'' of the Galaxy. Understanding the
X-ray morphology of the environment surrounding Sgr A* will ultimately provide
us with a greater precision in modeling the accretion of gas onto this object,
which appears to be relatively underluminous compared to its brethren in the
nuclei of other galaxies.


title: Accurate Redshifts and Classifications for 110 Radio-Loud AGNs

abstract:
  We report accurate redshifts of 110 active galaxies (mostly radio-loud
objects at z<0.4) observed in the course of a survey to find broad,
double-peaked emission lines. These redshifts are measured from the narrow
emission lines of these objects and are accurate to at least one part in 10^4 .
For each object we determine a redshift from high- and low-ionization lines
separately, as well as an average redshift from all the available lines. We
find that in about 15% of cases, the low-ionization lines yield a slightly
higher redshift than the high-ionization lines; the average redshift difference
amounts to a velocity difference of approximately 80 km/s. In addition to the
redshift measurements we also report revised redshifts for two objects as well
as new classifications for three narrow-line objects.


title: On the Photometric Accuracy of RHESSI Imaging and Spectrosocopy

abstract:
  We compare the photometric accuracy of spectra and images in flares observed
with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI)}spacecraft. We
test the accuracy of the photometry by comparing the photon fluxes obtained in
different energy ranges from the spectral-fitting software SPEX with those
fluxes contained in the images reconstructed with the Clean, MEM, MEM-Vis,
Pixon, and Forward-fit algorithms. We quantify also the background fluxes, the
fidelity of source geometries, and spatial spectra reconstructed with the five
image reconstruction algorithms. We investigate the effects of grid selection,
pixel size, field-of-view, and time intervals on the quality of image
reconstruction. The detailed parameters and statistics are provided in an
accompanying CD-ROM and web page. We find that Forward-fit, Pixon, and Clean
have a robust convergence behavior and a photometric accuracy in the order of a
few percents, while MEM does not converge optimally for large degrees of
freedom (for large field-of-views and/or small pixel sizes), and MEM-Vis
suffers in the case of time-variable sources. This comparative study documents
the current status of the RHESSI spectral and imaging software, one year after
launch.


title:
The baryonic mass-velocity relation; clues to feedback processes during
  structure formation and the cosmic baryon inventory

abstract:
  We show that a global relation between baryonic mass and virial velocity can
be constructed from the scale of dwarf galaxies up to that of rich galaxy
clusters. The slope of this relation is close to that expected if dark matter
halos form in the standard hierarchical cosmogony and capture a universal
baryon fraction, once the details of halo structure and the adiabatic
contraction of halos due to cooling gas are taken into account. The scatter and
deficiency of baryons within low mass halos ($V_{vir} < 50$ km/s) is consistent
with the expected suppression of gas accretion by photo-evaporation due to the
cosmic UV background at high redshift. The data are not consistent with
significant gas removal from strong supernovae winds unless the velocities of
galaxies measured from their gas kinematics are significantly lower than the
true halo velocities for objects with $V_{vir} < 100$ km/s. Thus models such as
$\Lambda$CDM with a steep mass function of halos may find it difficult to
reproduce both the baryonic mass-velocity relation presented here whilst at the
same time reproducing the flat luminosity/HI function of galaxies. Galaxies
hold about 10% of the baryons in the Universe, which is close to the collapsed
mass fraction expected within hierarchical models on these scales, suggesting a
high efficiency for galaxy formation. Most of the baryons are expected to be
evenly distributed between diffuse intergalactic gas in low density
environments and the intra-galactic medium within galaxy groups.


title: Tomographic 3D-Modeling of the Solar Corona with FASR

abstract:
  The "Frequency-Agile Solar Radiotelescope" (FASR) litteraly opens up a new
dimension in addition to the 3D Euclidian geometry: the frequency dimension.
The 3D geometry is degenerated to 2D in all images from astronomical
telescopes, but the additional frequency dimension allows us to retrieve the
missing third dimension by means of physical modeling. We call this type of 3D
reconstruction "Frequency Tomography". In this study we simulate a realistic 3D
model of an active region, composed of 500 coronal loops with the 3D geometry
[x(s),y(s),z(s)] constrained by magnetic field extrapolations and the physical
parameters of the density n_e(s) and temperature T_e(s) given by hydrostatic
solutions. We simulate a series of 20 radio images in a frequency range of
f=0.1-10 GHz, anticipating the capabilities of FASR, and investigate what
physical information can be retrieved from such a dataset. We discuss also
forward-modeling of the chromospheric and Quiet Sun density and temperature
structure, another primary goal of future FASR science.


title: The Pulsar-White Dwarf-Planet System in Messier 4: Improved Astrometry

abstract:
  A young and undermassive white dwarf has been identified as the possible
companion to the millisecond pulsar PSR B1620-26 in Messier 4. This association
is important as it then helps constrain the mass of the third body in the
system to be of order a few times that of Jupiter. The presence of this planet
in M4 has critical implications for planetary formation mechanisms in
metal-poor environments such as globular clusters and the early Universe. The
identification of the white dwarf is purely via the agreement in position
between it and the pulsar and was limited by the accuracy of the pointing of
HST which is +/-0.7 arcsec. We have redetermined the position of the white
dwarf using ground-based data tied to USNOB-1.0 and find that the pulsar and
white dwarf are now coincident to within 0.12 +/- 0.13 arcsec further
strengthening the case for association between the two. We have also attempted
to improve the proper motion measurement of the white dwarf by a maximum
likelihood analysis of the stellar positions measured over a baseline of 5
years. While the errors are reduced by almost a factor of 6 from our previous
work, we still have not resolved the cluster's intrinsic dispersion in proper
motion. Thus the proper motion of the white dwarf with respect to the cluster
itself is still not known although it is very small and is within 2-sigma of
that of the cluster internal dispersion.


title: Structure and Dynamics of Stellar Winds in High-mass X-ray Binaries

abstract:
  A review of spectroscopic results obtained from Chandra High Energy
Transmission Grating Spectrometer and XMM-Newton Reflection Grating
Spectrometer observations of several wind-fed high-mass X-ray binaries (HMXBs)
is presented. These observations allow us to study the structure of the stellar
wind in more detail and provide, for the first time, a dyanmical view of the
X-ray photoionized wind that surrounds the compact object. At the same time,
however, they are also providing us with numerous puzzles that cannot be
explained in terms of simple models. For example, simple spherically-symmetric
wind models cannot explain the observed orbital-phase variability of the line
intensities and shapes, which may be caused by intrinsic asymmetries due to the
presence of the compact object and/or more complicated radiative transfer
effects. The observed line shifts are smaller than those expected from
extensions of simple wind models of isolated OB supergiants. In addition,
several novel spectroscopic discoveries have been made, including: (1) P-Cygni
lines from an expanding wind, (2) detection of multiple Si K fluorescent lines
from a wide range of charge states, (3) Compton scattered Fe K lines from a
cold medium. We discuss how these spectroscopic diagnostics can be used to
understand some of the global properties of stellar winds in HMXBs.


title: Gamma-ray bursts from alternating-current jets

abstract:
  We propose a gamma-ray burst scenario involving relativistic jets dominated
by Poynting flux with alternating toroidal magnetic fields. Such a structure
may arise naturally if the jet is formed and powered by the accretion flow in
the core of a collapsar. We conjecture that the polarity of the toroidal
magnetic field changes randomly due to hydromagnetic turbulence driven by the
magneto-rotational instability (MRI), with the typical reversal time determined
by the time scale for amplifying magnetic fields up to a dynamically important
level. Poynting flux-dominated jets with reversing B-fields provide a natural
and efficient way to dissipate energy via the reconnection process. Gamma-rays
are produced at the spatially separated reconnection sites. In this scenario,
the emergent synchrotron radiation can be highly polarized and can form both
smooth and spiky light curves. We note the possibility that cold and dense
filaments can form in the reconnection zones as the result of thermal
instability. One could then explain the production of very hard X-ray spectra,
as due to bound-free absorption of the synchrotron radiation.


title: Review of Coronal Oscillations - An Observer's View

abstract:
  Recent observations show a variety of oscillation modes in the corona. Early
non-imaging observations in radio wavelengths showed a number of fast-period
oscillations in the order of seconds, which have been interpreted as fast
sausage mode oscillations. TRACE observations from 1998 have for the first time
revealed the lateral displacements of fast kink mode oscillations, with periods
of ~3-5 minutes, apparently triggered by nearby flares and destabilizing
filaments. Recently, SUMER discovered with Doppler shift measurements loop
oscillations with longer periods (10-30 minutes) and relatively short damping
times in hot (7 MK) loops, which seem to correspond to longitudinal slow
magnetoacoustic waves. In addition, propagating longitudinal waves have also
been detected with EIT and TRACE in the lowest density scale height of loops
near sunspots. All these new observations seem to confirm the theoretically
predicted oscillation modes and can now be used as a powerful tool for
``coronal seismology'' diagnostic.


title:
A new Method to Constrain the Iron Abundance from Cooling Delays in
  Coronal Loops

abstract:
  Recent observations with TRACE reveal that the time delay between the
appearance of a cooling loop in different EUV temperature filters is
proportional to the loop length, dt_12 ~ L. We model this cooling delay in
terms of radiative loss and confirm this linear relationship theoretically. We
derive an expression that can be used to constrain the coronal iron enhancement
alpha_Fe=A_Fe^cor/A_Fe^Ph relative to the photospheric value as function of the
cooling delay dt_12, flux F_2, loop width w, and filling factor q_w < 1. With
this relation we find upper limits on the iron abundance enhancement of
alpha_Fe < 4.8+/-1.7 for 10 small-scale nanoflare loops, and alpha_Fe <
1.4+/-0.4 for 5 large-scale loops, in the temperature range of T~1.0-1.4 MK.
This result supports the previous finding that low-FIP elements, including Fe,
are enhanced in the corona. The same relation constitutes also a lower limit
for the filling factor, which is q_w > 0.2+/-0.1 and q_w > 0.8+/-0.2 for the
two groups of coronal loops.


title:
Sunyaev-Zel'dovich Effect by Multiple Sctattering : Numerical Solution
  of the Transfer Equations

abstract:
  The radiative transfer equations for multiple inverse Compton scattering of
the Cosmic Microwave Background Radiation (CMBR) by the hot intra-cluster
electrons are solved numerically. The spherical isothermal and inhomogeneous
$\beta$ model has been considered for the electron distribution. The anisotropy
of the CMBR caused by scattering, known as thermal Sunyaev-Zel'dovich effect,
along the radial axis of the medium is compared with the analytical solution of
Kompaneets equation. The X-ray data of several clusters of galaxies at low
redshifts provide an estimation of the central electron density $n_0$ to be of
the order $10^{-3}$. It is found that for this value of $n_0$ the effect of
multiple scattering is negligible. The numerically calculated anisotropy along
the radial axis matches well with the analytical solution that describes single
scattering. The result incorporating multiple scattering is fitted with the
recent observation of Sunyaev-Zel'dovich effect in the cluster Abell 2163. It
is shown that if $n_0$ is greater by an order of magnitude, which could be
possible for cluster of galaxies at comparatively higher redshift, multiple
scattering would play a significant role at the Wien region of the anisotropy
spectrum. A fitting formula for the correction to the Sunyaev-Zel'dovich effect
due to multiple scattering is provided.


title:
The Stochastic Gravitational-Wave Background and the Inflation to
  Radiation Transition in the Early Universe

abstract:
  In this paper we calculate the gravitational-wave power-spectra corresponding
to different types of transitions between the inflationary regime and the
radiation era. We study four cases, where inflation is followed by a stiff
matter phase, or by a dust dominated phase, or by a combination of the two,
before the universe enters the radiation era. Use is made of differential
equations for the Bogoliubov coefficients, allowing us to model all the
transitions between the different eras as continuous. New features appear, for
frequencies above 10^{7} rad/s in an otherwise flat part of the spectrum.


title:
Mapping the thermal history of the Universe with the new generation of
  CMB spectrum space experiments

abstract:
  We have studied the implications of the new generation of CMB spectrum space
experiments for our knowledge of the thermal history of the Universe.
  The combination of two experiments with the sensitivity and the frequency
coverage jointly forseen for DIMES and FIRAS II will be able to greatly change
our vision of the capability of the CMB spectrum information to constrain
physical processes at different cosmic ages. The limits on the energy
dissipations at the all cosmic times accessible to CMB spectrum investigations
(z < z_therm) could be improved by about two order of magnitudes and even
dissipation processes with DE/E ~ 10^-6 could be detected and possibly
accurately studied. These results are possible because such levels of accuracy
on a so wide frequency range allow to remove the approximate degeneracy both
between free-free and Bose-Einstein (BE) like distortions and between
Comptonization and BE-like distortions.
  Finally, we discussed the different signatures imprinted on the CMB spectrum
by some late astrophysical and particle decay models recently proposed in the
literature and possibly related to the reionization of the Universe indicated
by WMAP, and compared them with the sensitivity of such classes of CMB space
spectrum experiments.


title:
IBIS preliminary results on Cygnus X-1 spectral and temporal
  characteristics

abstract:
  We report preliminary results of a broadband spectral and temporal study of
the black-hole binary Cyg X-1 performed with the IBIS telescope. Cyg X-1 was
the first pointed celestial target of IBIS during the INTEGRAL Performance and
Verification Phase, 2002 Nov.-Dec., for a total observing time of 2 Ms in both
staring and dithering mode. Here, we report on only the staring, on-axis,
observation performed in a stable instrument configuration. During the
observing period the source was in its characteristic low/hard state, in which
a few flares and dips have been detected. The IBIS/ISGRI results demonstrate
that the INTEGRAL observatory offers a unique capability for studying
correlations between hardness and/or flux in different bands over a wide photon
energy range. One of our new results is finding that the hardness-flux
correlation changes the sign twice over the 20-220 keV; first from positive to
negative at 50 keV, and then back to positive at 120 keV. The former change
appears to be due to the spectral curvature introduced by variable Compton
reflection. The latter may be due spectral pivoting.


title: A Test for the Origin of Quasar Redshifts

abstract:
  It is commonly accepted that quasar redshifts have a cosmological character
and that most of the quasars are at Gigaparsec distances. However, there are
some cases where several quasars with completely different redshifts and a
nearby active galaxy are aligned in a certain way or occupy a very small patch
on the sky, which is claimed by some authors to be unlikely to happen by
chance. Is there a small subset of quasars with non-cosmological redshifts? For
quasars apparently associated with galaxies, we consider two scenarios for the
origin of their redshift: 1. a standard, cosmological scenario, 2. a
velocity-induced Doppler shift of a nearby object's spectrum (local, ejection
scenario). We argue for a simple astrometric test which can distinguish between
these two sources of quasar redshifts by constraining their proper motions.
  We give the predictions for the maximum possible proper motions of a quasar
for the cosmological and local scenarios of the origin of their redshifts. We
apply these theoretical results to the Bukhmastova (2001) catalog, which
contains more than 8000 close QSO-galaxy associations. In the standard
interpretation of quasar redshifts, their typical proper motions are a fraction
of micro arc-second, and beyond the reach of planned astrometric missions like
GAIA and SIM. On the other hand, the quasars ejected from local AGNs at
velocities close to the speed of light would have proper motions 5-6 orders of
magnitude larger, which would easily be measurable with future astrometric
missions. The distributions of proper motions for the cosmological and local
scenarios are very well separated. Moreover, the division corresponds nicely to
the expected accuracy from GAIA and SIM.


title: The consistency relation in braneworld inflation

abstract:
  The braneworld cosmology, in which our universe is imbedded as a hypersurface
in a higher dimensional bulk, has the peculiar property that the inflationary
consistency relation derived in a four-dimensional cosmology persists. This
consistency condition relates the ratio of tensor and scalar perturbation
amplitudes to the tensor spectral index produced during an epoch of slow-roll
scalar field inflation. We attempt to clarify this surprising degeneracy. Our
argument involves calculating the power spectrum of scalar field fluctuations
around geometries perturbed away from the exact de Sitter case. This
calculation is expected to be valid for perturbations which would not cause a
late-time acceleration of the universe. We use these results to argue that the
emergence of the same consistency relation in the braneworld can be connected
with a specific property, that five-dimensional observables smoothly approach
their four-dimensional counterparts as one takes the brane to infinite tension.
We exhibit an explicit example where this does not occur, and in which a
consistency relation does not persist.


title: Entropy Evolution of the Gas in Cooling Flow Clusters

abstract:
  We emphasise the importance of the gas entropy in studying the evolution of
cluster gas evolving under the influence of radiative cooling. On this basis,
we develop an analytical model for this evolution. We then show that the
assumptions needed for such a model are consistent with a numerical solution of
the same equations. We postulate that the passive cooling phase ends when the
central gas temperature falls to very low values. It follows a phase during
which an unspecified mechanism heats the cluster gas. We show that in such a
scenario the small number of clusters containing gas with temperatures below
about 1 keV is simply a consequence of the radiative cooling.


title: Can high-velocity stars reveal black holes in globular clusters?

abstract:
  We estimate the number of individual, fast-moving stars observable in
globular clusters under the assumption that the clusters contain massive
central black holes which follow the galactic black-hole mass vs. sigma
relationship. We find that radial velocity measurements are unlikely to detect
such stars, but that proper motion studies could reveal such stars, if they
exist, in the most likely clusters. Thus, HST proper motion studies can test
this hypothesis in a few nearby clusters.


title: The Pierre Auger Observatory

abstract:
  One of the most fascinating puzzles in particle astrophysics today is that of
the origin and nature of the highest energy cosmic rays. The Pierre Auger
Observatory (PAO), currently under construction in Province of Mendoza,
Argentina, and with another site planned in the Northern hemisphere, is a major
international effort to make precise, high statistics studies of the highest
energy cosmic rays. It is the first experiment designed to work in a hybrid
mode incorporating both a ground-based array of 1600 particle detectors spread
over 3000 km$^2$ with fluorescence telescopes placed on the boundaries of the
surface array. The current status of the observatory is presented and prospects
for the future discussed.


title:
Gamma-rays From Neutralino Annihilation in Milky Way Substructure: What
  Can We Learn?

abstract:
  We estimate the probability of detecting gamma-rays from the annihilation of
neutralino dark matter in the substructure of the Milky Way. We characterize
substructure statistically based on Monte Carlo realizations of the formation
of a Milky Way-like halo using semi-analytic methods that have been calibrated
against N-body simulations. We find that it may be possible for the upcoming
GLAST and VERITAS experiments, working in concert, to detect gamma-rays from
dark matter substructure if $\Mchi \lsim 100 \GeV$, while for $\Mchi \gsim 500
\GeV$ such a detection seems unlikely. We investigate the effects of the
underlying cosmological model and find that the probability of detection is
sensitive to the primordial power spectrum of density fluctuations on small
(galactic and sub-galactic) scales. We conclude that the lack of such a
detection reveals little about the supersymmetric parameter space due to the
uncertainties associated with the properties of substructure and cosmological
parameters.


title:
Generating Equilibrium Dark Matter Halos: Inadequacies of the Local
  Maxwellian Approximation

abstract:
  We describe an algorithm for constructing N-body realizations of equilibrium
spherical systems. A general form for the mass density rho(r) is used, making
it possible to represent most of the popular density profiles found in the
literature, including the cuspy density profiles found in high-resolution
cosmological simulations. We demonstrate explicitly that our models are in
equilibrium. In contrast, many existing N-body realizations of isolated systems
have been constructed under the assumption that the local velocity distribution
is Maxwellian. We show that a Maxwellian halo with an initial r^{-1} central
density cusp immediately develops a constant-density core. Moreover, after just
one crossing time the orbital anisotropy has changed over the entire system,
and the initially isotropic model becomes radially anisotropic. These effects
have important implications for many studies, including the survival of
substructure in cold dark matter (CDM) models. Comparing the evolution and
mass-loss rate of isotropic Maxwellian and self-consistent Navarro, Frenk, &
White (NFW) satellites orbiting inside a static host CDM potential, we find
that the former are unrealistically susceptible to tidal disruption. Thus,
recent studies of the mass-loss rate and disruption timescales of substructure
in CDM models may be compromized by using the Maxwellian approximation. We also
demonstrate that a radially anisotropic, self-consistent NFW satellite loses
mass at a rate several times higher than that of its isotropic counterpart on
the same external tidal field and orbit.


title: Inferring the coronal flaring patterns in AGN from reverberation maps

abstract:
  The relativistically broadened iron K-alpha line at 6.4 keV observed in the
Seyfert 1 galaxy MCG-6-30-15 has provided a probe of the strong-gravity
environment near a black hole, in particular suggesting that it is rapidly
spinning. An important variable in such analyses is the geometry of the
illuminating source. We present a new technique which constrains this geometry
based on the spectral line shape, based on a model of discrete, point-like
flaring regions in the X-ray corona. We apply it to simulated reverberation
maps and give examples of successful reconstructions of complex coronal flaring
patterns. For time-averaged spectral lines the problem is highly degenerate,
and so its inversion more challenging. We quantify this degeneracy and give a
measure of the spatial accuracy of the method in this case, before checking
that it is consistent with the existing picture of MCG-6-30-15 by applying it
to recent data from XMM-Newton.


title: Supernova Neutrino-Nucleus Astrophysics

abstract:
  In this brief review we explore the role of neutrino-nucleus interactions in
core-collapse supernovae and discuss open questions. In addition implications
of neutrino mass and mixings in such environments are summarized.


title: On the Formation of Brown Dwarfs

abstract:
  The observational properties of brown dwarfs pose challenges to the theory of
star formation. Because their mass is much smaller than the typical Jeans mass
of interstellar clouds, brown dwarfs are most likely formed through secondary
fragmentation processes, rather than through the direct collapse of a molecular
cloud core. In order to prevent substantial post-formation mass accretion,
young brown dwarfs must leave the high density formation regions in which they
form. We propose here that brown dwarfs are formed in the circumbinary disks.
Through post-formation dynamical interaction with their host binary stars,
young brown dwarfs are either scattered to large distance or removed, with
modest speed, from their cradles.


title:
Early Growth and Efficient Accretion of Massive Black Holes at High
  Redshift

abstract:
  Black-hole masses of the highest redshift quasars (4 <~ z <~ 6) are estimated
using a previously presented scaling relationship, derived from reverberation
mapping of nearby quasars, and compared to quasars at lower redshift. It is
shown that the central black holes in luminous z >~ 4 quasars are very massive
(>~ 10^9 solar masses). It is argued that the mass estimates of the high-z
quasars are not subject to larger uncertainties than those for nearby quasars.
Specifically, the large masses are not overestimates and the lack of similarly
large black-hole masses in the nearby Universe does not rule out their
existence at high-z. However, AGN host galaxies do not typically appear fully
formed or evolved at these early epochs. This supports scenarios in which black
holes build up mass very fast in a radiatively inefficient (or obscured) phase
relative to the stars in their galaxies. Additionally, upper envelopes of
black-hole mass of approximately 10^{10} solar masses and bolometric luminosity
of ~ 10^{48} erg/s are observed at all redshifts.


title: Rapidly rotating superfluid neutron stars in Newtonian dynamics

abstract:
  We develop a formulation for constructing and examining rapidly rotating
Newtonian neutron star models that contain two superfluids, taking account of
the effect of the rotation velocity difference between two superfluids. We
assume neutron stars to be composed of the superfluid neutrons and the mixture
of the superfluid protons and the normal fluid electrons. To describe Newtonian
dynamics of the two superfluids, the Newtonian version of the so-called
two-fluid formalism is employed. The effect of the rotation velocity difference
on the structure of equilibrium state is treated as a small perturbation to
rapidly rotating superfluid stars whose angular velocities of two superfluids
are assumed to be exactly the same. We derive basic equations for the perturbed
structures of rapidly rotating superfluid stars due to the rotation velocity
difference between two superfluids. Assuming the superfluids to obey a simple
analytical equation of state proposed by Prix, Comer, and Andersson, we obtain
numerical solutions for the perturbations and find that the density
distributions of the superfluids are strongly dependent on the parameter
$\sigma$ which appears in the analytical equation of state and characterizes
the so-called symmetry energy. It is also found that if Prix et al.'s
analytical equation of state is assumed, the perturbations can be represented
in terms of the universal functions that are independent of the parameters of
the equation of state.


title: The X-ray emission of the Crab-like pulsar PSR J0537-6910

abstract:
  In this paper we present some preliminary result on the spectral and timing
analysis of the X-ray pulsed emission from the 16 ms pulsar PSR J0537-6910 in
the energy range 0.1--30 keV, based on archival BeppoSAX and RossiXTE
observations. This pulsar, discovered by Marshall et al.(1998) in the LMC field
with RXTE, is the fastest spinning pulsar associated with a supernova remnant.
It is characterized by strong glitch activity with the highest rate of all
known Crab-like system.


title: Outflows from Quasars and Ultraluminous X-ray Sources

abstract:
  Mass outflows from Eddington-limited accreting compact objects appear to be a
very widespread phenomenon. They may provide the soft excess observed in
quasars and ULXs, and imply that such objects have a major effect on their
surroundings. In particular they allow a simple parameter-free argument for the
M_BH-sigma relation for galaxies, and offer a straightforward interpretation of
the emission nebulae seen around ULXs.


title: INTEGRAL timing and localization performance

abstract:
  In this letter we report on the accuracy of the attitude, misalignment, orbit
and time correlation which are used to perform scientific analyses of the
INTEGRAL data. The boresight attitude during science pointings has an accuracy
of 3 arcsec. At the center of the field, the misalignments have been calibrated
leading to a location accuracy of 4 to 40 arcsec for the different instruments.
The spacecraft position is known within 10 meters. The relative timing between
instruments could be reconstructed within 10 microsec and the absolute timing
within 40 microsec.


title: Generic description of CMB power spectra

abstract:
  Taking advantage of the smoothness of CMB Cl power spectra, we derive a
simple and model-independent parameterization of their measurement. It allows
to describe completely the spectrum, ie. provide an estimate of the value and
the error for any real l point at the percent level, down to low l multipole.
We provide this parameterization for WMAP first year data and show that the
spectrum is consistent with the smoothness hypothesis. We also show how such a
parameterization allows to retrieve the Cl spectra from the measurement of
Fourier rings on the sky (Gamma(m)) or from the angular correlation function
(c(theta))


title: The energy balance in polars revisited

abstract:
  In the EXOSAT and ROSAT eras a significant number of polars were found to
show a soft/hard X-ray ratio much greater than that expected from the standard
accretion shock model. This was known as the `soft X-ray excess'. We have made
an snapshot survey of polars using XMM-Newton and determined their soft/hard
ratios. We find that less than one in five of systems show a significant soft
X-ray excess, while the rest show ratios consistent with that predicted by the
standard model. We have investigated the discrepancy between this and the
previous investigations by re-examining all the available ROSAT PSPC pointed
observations of polars using more recent calibrations than in the original
studies. We find that these data show an energy balance ratio which is broadly
consistent with that of our XMM-Newton results. We conclude that the previous
studies were affected by the data being less well calibrated. We discuss which
physical mechanisms might give rise to a high soft X-ray excess and whether
systems with high ratios show more variation in soft X-rays. Surprisingly, we
find that 6 out of 21 systems found in a high accretion state did not show a
distinct soft X-ray component. Two systems showed one pole with such a
component and one which did not. Based on the ratio of the observed soft X-ray
to UV flux measurements (which were obtained simultaneously using the Optical
Monitor) we suggest that this is because the reprocessed component in these
systems is cool enough to have moved out of the soft X-ray band and into the
EUV or UV band.


title:
Expected properties of primeval galaxies and confrontation with existing
  observations

abstract:
  We discuss the expected spectral properties of starbursts of zero and very
low metallicity covering their restframe EUV and UV to optical spectra. The
main criteria to establish such a "primeval" nature are summarised. Finally we
compare these expected properties, including continuum and emission lines, to
existing observations of high-z galaxies and briefly discuss future
observational prospects.


title:
The depolarisation properties of powerful radio sources: breaking the
  radio-power vs. redshift degeneracy

abstract:
  We define 3 samples of extragalactic radio sources of type FRII, containing
26 objects in total. The control sample consists of 6C and 7C sources with
radio powers of around 10e27 W\Hz at 151 MHz and redshifts of around z=1. The
other samples contain 3CRR sources with either comparable redshifts but radio
powers about a decade larger or with comparable radio powers but redshifts
around z = 0.4. We use these samples to investigate the possible evolution of
their depolarisation and rotation measure properties with redshift and radio
power independently. We used VLA data for all sources at 4800 MHz and two
frequencies within the 1400 MHz band, either from our own observations or from
the archive. We present maps of the total intensity flux, polarised flux,
depolarisation, spectral index, rotation measure and magnetic field direction
where not previously published. Radio cores were detected in twelve of the
twenty-six radio sources. Fourteen of the sources show a strong
Laing-Garrington effect but almost all of the sources show some depolarisation
asymmetry. All sources show evidence for an external Faraday screen being
responsible for the observed depolarisation. We find that sources at higher
redshift are more strongly depolarised. Rotation measure shows no trend with
either redshift or radio power, however variations in the rotation measure
across individual sources increase with the redshift of the sources but do not
depend on their radio power.


title:
A precise HST parallax of the cataclysmic variable EX Hydrae, its system
  parameters, and accretion rate

abstract:
  Using the HST Fine Guidance Sensor, we have measured a high precision
astrometric parallax of the cataclysmic variable EX Hydrae, pi=15.50+-0.29mas.
  From the wavelength-integrated accretion-induced energy flux, we derive a
quiescent accretion luminosity for EX Hya of Lacc = (2.6+-0.6)x10e32 erg. The
quiescent accretion rate then is Mdot=(6.2\+-1.5)x10e-11
(M1/0.5Msun)^(-1.61})Msun/yr. The time-averaged accretion rate, which includes
a small correction for the rare outbursts, is 6% higher. We discuss the system
parameters of EX Hya and deduce M1=0.4-0.7Msun, M2=0.07-0.10Msun, and
i=76.0deg-77.6deg, using recent radial velocity measurements of both components
and restrictions imposed by other observational and theoretical constraints. We
conclude that the secondary is undermassive, overluminous, and expanded over a
ZAMS star of the same mass. Near the upper limit to M1, the accretion rate of
the white dwarf coincides with that due to near-equilibrium angular momentum
loss by gravitational radiation and angular momentum transfer from the orbit
into the spin-up of the white dwarf. Near the lower mass limit, the
correspondingly higher accretion rate requires that either an additional
angular momentum loss process is acting besides gravitational radiation or that
accretion occurs on a near-adiabatic time scale. The latter possibility would
imply that EX Hya is in a transient phase of high mass transfer and the
associated spin-up of the white dwarf.


title: Self-Induced Formaton of Metal-Rich Globulars in Bulges?

abstract:
  Taken together, key latest observations assume that (i) old metal-rich
globular cluster populations (MRGCPs) in bulges were able to form due to
essentially increased, self(internally)-induced star formation rate (SFR) in
the hosts, while galaxy merging played an additional role; (ii) massive star
cluster populations (MSCPs) in irregulars may be young, less prominent
counterparts of the old MRGCPs in spheroids.


title: First INTEGRAL observations of GRS 1915+105

abstract:
  We present data from the first of six monitoring Open Time observations of
GRS 1915+105 undertaken with the orbiting INTEGRAL satellite. The source was
clearly detected with all three X-ray and gamma-ray instruments on board. GRS
1915+105 was in a highly variable state, as demonstrated by the JEM X-2 and
ISGRI lightcurves. These and simultaneous RXTE/PCA lightcurves point to a novel
type of variability pattern in the source. In addition, we fit the combined JEM
X-2 and ISGRI spectrum between 3-300 keV with a disk blackbody + powerlaw model
leading to typical parameter values found earlier at similar luminosity levels.
A new transient, IGR J19140+098, was discovered during the present observation.


title: The cosmological evolution of metal enrichment in quasar host galaxies

abstract:
  We study the gas metallicity of quasar hosts using cosmological hydrodynamic
simulations of the Lambda-cold dark matter model. Galaxy formation in the
simulations is coupled with a prescription for black hole activity enabling us
to study the evolution of the metal enrichment in quasar hosts and hence
explore the relationship between star/spheroid formation and black hole
growth/activity. We find a steep radial metallicity gradient in quasar host
galaxies, with gas metallicities close to solar values in the outer parts but
becoming supersolar in the center. The hosts of the rare bright quasars at
z~5-6 have star formation rates of several hundred solar masses per year and
halo masses of order ~10^12 solar masses. Already at these redshifts they have
supersolar (Z ~2-3 solar) central metallicities, with a mild dependence of
metallicity on luminosity, consistent with observed trends. The mean value of
metallicity is sensitive to the assumed quasar lifetime, providing a useful new
probe of this parameter. We find that lifetimes from 10^7-4x10^7yr are favored
by comparison to observational data. In both the models and observations, the
rate of evolution of the mean quasar metallicity as a function of redshift is
generally flat out to z ~ 4-5. Beyond the observed redshift range and out to
redshift z ~ 6-8, we predict a slow decline of the mean central metallicity
towards solar and slightly subsolar values as we approach the epoch of the
first significant star formation activity