title: Extrinsic Radio Variability of JVAS/CLASS Gravitational Lenses

abstract:
  We present flux-ratio curves of the fold and cusp (i.e. close multiple)
images of six JVAS/CLASS gravitational lens systems. The data were obtained
over a period of 8.5 months in 2001 with the Multi-Element Radio-Linked
Interferometer Network (MERLIN) at 5-GHz with 50 mas resolution, as part of a
MERLIN Key-Project. Even though the time delays between the fold and cusp
images are small (<~1 day) compared to the time-scale of intrinsic source
variability, all six lens systems show evidence that suggests the presence of
extrinsic variability. In particular, the cusp images of B2045+265 -- regarded
as the strongest case of the violation of the cusp relation (i.e. the sum of
the magnifications of the three cusp images add to zero) -- show extrinsic
variations in their flux-ratios up to ~40 percent peak-to-peak on time scales
of several months. Its low Galactic latitude of b=-10 degree and a
line-of-sight toward the Cygnus superbubble region suggest that Galactic
scintillation is the most likely cause. The cusp images of B1422+231 at b=+69
degree do not show strong extrinsic variability. Galactic scintillation can
therefore cause significant scatter in the cusp and fold relations of some
radio lens systems (up to 10 percent rms), even though these relations remain
violated when averaged over a <~1 year time baseline.


title: Covariant Magnetoionic Theory I: Ray Propagation

abstract:
  Accretion onto compact objects plays a central role in high energy
astrophysics. In these environments, both general relativistic and plasma
effects may have significant impacts upon the propagation of photons. We
present a full general relativistic magnetoionic theory, capable of tracing
rays in the geometric optics approximation through a magnetised plasma in the
vicinity of a compact object. We consider both the cold and warm, ion and pair
plasmas. When plasma effects become large the two plasma eignemodes follow
different ray trajectories resulting in a large observable polarisation. This
has implications for accreting systems ranging from pulsars and X-ray binaries
to AGN.


title:
Giant H II regions in the merging system NGC 3256: Are they the
  birthplaces of globular clusters?

abstract:
  CCD images and spectra of ionized hydrogen in the merging system NGC3256 were
acquired as part of a kinematic study to investigate the formation of globular
clusters (GC) during the interactions and mergers of disk galaxies. This paper
focuses on the proposition that giant H II regions, with an H_alpha luminosity
> 1.5 x 10^{40} erg s^{-1}, are birthplaces of young populous clusters (YPC).
We estimate 900 30-Doradus-like H II regions formed during the galaxy-galaxy
interaction which created NGC 3256. A specific frequency argument for forming a
sufficient number of GC, assuming that the NGC3256 merger remnant will be an
elliptical galaxy, only requires that about 10% of these H II regions harbor
YPC which survive several Gyr and have masses at least as large as the cluster
R136 in 30 Doradus.


title: NGC 3256: Kinematic anatomy of a merger

abstract:
  We have used the Australia Telescope Compact Array to image the neutral
hydrogen in the merging system NGC 3256, to test the idea that globular
clusters (GC) form during the interactions and mergers of disk galaxies. We
compare our observations with hydrodynamical numerical simulations, from the
literature, to examine the hypothesis that the H I fragments with masses
greater than 10$^{7\pm1} \mo$ are sites of GC formation. We appear to have
detected detached H I fragments in the vicinity of NGC 3256. These fragments,
with masses ~10^7 solar masses, may have little dark matter content which is
also a characteristic of globular clusters, and so our observations support the
hypothesis that globular clusters form in the type of interaction that resulted
in NGC 3256.


title: On Friedmann integrals coincidence

abstract:
  Expansion of the two-component universe with arbitrary spatial curvature has
been considered. It has been shown that the Friedmann integrals of the almost
flat universe do not coincide.


title: Real time localization of Gamma Ray Bursts with INTEGRAL

abstract:
  The INTEGRAL satellite has been successfully launched in October 2002 and has
recently started its operational phase. The INTEGRAL Burst Alert System (IBAS)
will distribute in real time the coordinates of the GRBs detected with
INTEGRAL. After a brief introduction on the INTEGRAL instruments, we describe
the main IBAS characteristics and report on the initial results. During the
initial performance and verification phase of the INTEGRAL mission, which
lasted about two months, two GRBs have been localized with accuracy of about
2-4 arcmin. These observations have allowed us to validate the IBAS software,
which is now expected to provide quick (few seconds delay) and precise (few
arcmin) localization for about 10-15 GRBs per year.


title: Jets in Supermassive and Stellar-Mass Black Holes

abstract:
  Relativistic outflows are a common phenomenon in accreting black holes.
Despite the enormous differences in scale, stellar-mass black holes in X-ray
binaries and collapsars, and super-massive black holes at the dynamic centre of
galaxies are sources of jets with analogous physical properties. Synergism
between the research on microquasars, gamma-ray bursts, and Active Galactic
Nuclei should help to gain insight into the physics of relativistic jets seen
everywhere in the Universe.


title: CO Emission from z>3 Radio Galaxies

abstract:
  We report on the detection of the CO(4-3) line with the IRAM Plateau de Bure
Interferometer in two z>3 radio galaxies, doubling the number of successful
detections in such objects. A comparison of the CO and Ly-alpha velocity
profiles indicates that in at least half of the cases, the CO is coincident in
velocity with associated HI absorption seen against the Ly-alpha emission. This
strongly suggests that the CO and HI originate from the same gas reservoir, and
could explain the observed redshift differences between the optical narrow
emission lines and the CO. The CO emission traces a mass of H_2 100-1000 times
larger than the HI and HII mass traced by Ly-alpha, providing sufficient gas to
supply the massive starbursts suggested by their strong thermal dust emission.


title: RX J1856.5-3754: Bare Quark Star or Naked Neutron Star ?

abstract:
  Recent Chandra observations have shown that the soft X-ray spectrum from the
isolated neutron star RX J1856.5-3754 is featureless and best fitted by a
blackbody, in contrast with the predictions of current neutron star atmospheric
models. The star distance (~120-140 pc) implies a radiation radius of at most
\~5-6 km, too small for any neutron star equation of state. Proposed
explanations for such a small radius include a reduced X-ray emitting region
(as a polar cap), or the presence of a more compact object, as a bare
quark/strange star. However, both interpretations rely on the presumption that
the quark star or the cap radiates a pure blackbody spectrum, and no
justification for this assumption has been presented yet. Here we discuss an
alternative possibility. Cool neutron stars (T < 10^6 K) endowed with high
magnetic field (B > 10^13 G) may suffer a phase transition in the outermost
layers. The neutron star is then left bare of the gaseous atmosphere. We
computed spectra from naked neutron stars with a surface Fe composition.
Depending on B, we found that the 0.1-2 keV emission can be featureless and
indistinguishable from a blackbody. Owing to the reduced surface emissivity,
the star only radiates ~30-50 % of the blackbody power, thus that the size of
the emitting region is larger than for a perfect planckian emitter. When
applied to RX J1856.5-3754 our model accounts for the observed X-ray properties
and solves the paradox of the small radius. The apparent star radius is ~10-12
km, consistent with equations of state of a neutron star. The optical emission
of RX J1856.5-3754 may be explained by the presence a thin gaseous shell on the
top of the Fe condensate.


title:
Orbital dynamics of three-dimensional bars: IV. Boxy isophotes in
  face-on views

abstract:
  We study the conditions that favour boxiness of isodensities in the face-on
views of orbital 3D models for barred galaxies. Using orbital weighted profiles
we show that boxiness is in general a composite effect that appears when one
considers stable orbits belonging to several families of periodic orbits. 3D
orbits that are introduced due to vertical instabilities, play a crucial role
in the face-on profiles and enhance their rectangularity. This happens because
at the 4:1 radial resonance region we have several orbits with boxy face-on
projections, instead of few rectangular-like x1 orbits, which, in a fair
fraction of the models studied so far, are unstable at this region. Massive
bars are characterized by rectangular-like orbits. However, we find that it is
the pattern speed that affects most the elongation of the boxy feature, in the
sense that fast bars are more elongated than slow ones. Boxiness in
intermediate distances between the center of the model and the end of the bar
can be attributed to x1v1 orbits, or to a combination of families related to
the radial 3:1 resonance.


title: Massive close binaries II

abstract:
  In the present review we summarize direct and indirect evidence that the
massive close binary frequency is very large. We then discuss the binary
evolutionary processes and we present a general massive close binary
evolutionary scheme. Finally, we highlight the importance of massive close
binaries for population number synthesis and the chemical evolution of
galaxies.


title: A search for X-ray variability in the open cluster NGC 2516

abstract:
  We present the results of a search for X-ray variability in the galactic open
cluster NGC 2516. This cluster has been observed on 8 occasions using
XMM-Newton making it an excellent target for such a study. We find 4 sources
which show significant variability, implying the detection of one significantly
variable source every 25ksec. All sources exhibit spectra which can be fitted
using an absorbed one or two temperature thermal plasma model. The brightest of
these flares also show a prominent Iron line near ~7.0keV. All 4 sources lie
near the observed main sequence of NGC 2516 suggesting they are cluster
members. We propose that at least 3 of the 4 objects are RS CVn systems. We
compare the properties of the brightest flare with those of solar flares.


title:
Cosmic Rays from PeV to ZeV, Stellar Evolution, Supernova Physics and
  Gamma Ray Bursts

abstract:
  The recent success of a proposal from some time ago to explain the spectrum
of cosmic rays allows some strong conclusions to be made on the physics of
supernovae: In the context of this specific proposal to explain the origin of
cosmic rays, the mechanism for exploding supernovae of high mass has to be the
one proposed by Bisnovatyi-Kogan more than 30 years ago, which was then based
on a broader suggestion by Kardashev: A combination of the effects of rotation
and magnetic fields explodes the star. Interestingly, this step then leads
inevitably to some further suggestions, useful perhaps for the study of gamma
ray bursts and the search of a bright standard candle in cosmology.


title:
The extended empirical process test for non-Gaussianity in the CMB, with
  an application to non-Gaussian inflationary models

abstract:
  In (Hansen et al. 2002) we presented a new approach for measuring
non-Gaussianity of the Cosmic Microwave Background (CMB) anisotropy pattern,
based on the multivariate empirical distribution function of the spherical
harmonics a_lm of a CMB map. The present paper builds upon the same ideas and
proposes several improvements and extensions. More precisely, we exploit the
additional information on the random phases of the a_lm to provide further
tests based on the empirical distribution function. Also we take advantage of
the effect of rotations in improving the power of our procedures. The suggested
tests are implemented on physically motivated models of non-Gaussian fields;
Monte-Carlo simulations suggest that this approach may be very promising in the
analysis of non-Gaussianity generated by non-standard models of inflation. We
address also some experimentally meaningful situations, such as the presence of
instrumental noise and a galactic cut in the map.


title:
A Study of Ultra-Luminous X-ray Sources from the Chandra Archive of
  Galaxies

abstract:
  The more than 80 nearby galaxies imaged with the Chandra Advanced CCD Imaging
Spectrometer have been analyzed in a search for Ultra-Luminous X-ray (ULX)
sources. The sample of galaxies span the range of Hubble morphological types
and include galaxies of various mass, gas content, and dynamical state. X-ray
characteristics of the resulting ensemble of ULX candidates are reported and
correlations with properties of the host galaxies are presented.


title:
Constraints on a planetary origin for the gap in GM Aurigae's
  protoplanetary disc

abstract:
  The unusual spectral energy distribution (SED) of the classical T Tauri star
GM Aurigae provides evidence for the presence of an inner disc hole extending
to several au. Using a combination of hydrodynamical simulations and Monte
Carlo radiative transport, we investigate whether the observed SED is
consistent with the inner hole being created and maintained by an orbiting
planet. We show that an ~ 2 M_Jupiter planet, orbiting at 2.5 au in a disc with
mass 0.047 M_sun and radius 300 au, provides a good match both to the SED and
to CO observations which constrain the velocity field in the disc. A range of
planet masses is allowed by current data, but could in principle be
distinguished with further observations between 3 and ~ 20 microns. Future high
precision astrometric instruments should also be able to detect the motion of
the central star due to an orbiting Jupiter mass planet. We argue that the
small number of T Tauri stars with SEDs resembling that of GM Aur is broadly
consistent with the expected statistics of embedded migrating planets.


title: The discovery of low-mass pre main sequence stars in Cepheus OB3b

abstract:
  We report the discovery of low-mass PMS stars in the younger subgroup of the
Cepheus OB3 association, Cep OB3b, using {\it UBVI} CCD photometry and
spectroscopy. The location of a PMS is well defined in a V versus (V-I)
colour-magnitude diagram (CMD). Multi-fibre spectroscopy results of
optically-selected PMS candidates confirm the T Tauri nature of 10 objects,
with equal numbers of classical and weak-line TTS. There are 6 other objects
which we classify as possible PMS stars. The newly discovered TTS have masses
in the range 0.9 - 3.0 Msun and ages from <1 to nearly 10 Myr, based on the
Siess et al.(2000) isochrones. Their location close to the O and B Their
location close to the O and B stars of the association demonstrates that
low-mass star formation is possible in this hostile environment dominated by
early-type stars and that the latter must have been less effective in eroding
the circumstellar discs of their lower mass siblings compared to other OB
associations (e.g. lambda Ori). We attribute this to the nature of the local
environment, speculating that the bulk of molecular material, which shielded
low-mass stars from the ionising radiation of their early-type siblings, has
only recently been removed (abridged).


title: Discovery of a New Nearby Star

abstract:
  We report the discovery of a nearby star with a very large proper motion of
5.06 +/- 0.03 arcsec/yr. The star is called SO025300.5+165258 and referred to
herein as HPMS (high proper motion star). The discovery came as a result of a
search of the SkyMorph database, a sensitive and persistent survey that is well
suited for finding stars with high proper motions. There are currently only 7
known stars with proper motions > 5 arcsec/yr. We have determined a preliminary
value for the parallax of 0.43 +/- 0.13 arcsec. If this value holds our new
star ranks behind only the Alpha Centauri system (including Proxima Centauri)
and Barnard's star in the list of our nearest stellar neighbors. The spectrum
and measured tangential velocity indicate that HPMS is a main-sequence star
with spectral type M6.5. However, if our distance measurement is correct, the
HPMS is underluminous by 1.2 +/- 0.7 mag.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Preliminary Maps and Basic Results

abstract:
  We present full sky microwave maps in five bands (23 to 94 GHz) from the WMAP
first year sky survey. Calibration errors are <0.5% and the low systematic
error level is well specified. The 2<l<900 anisotropy power spectrum is cosmic
variance limited for l<354 with a signal-to-noise ratio >1 per mode to l=658.
The temperature-polarization cross-power spectrum reveals both acoustic
features and a large angle correlation from reionization. The optical depth of
reionization is 0.17 +/- 0.04, which implies a reionization epoch of 180+220-80
Myr (95% CL) after the Big Bang at a redshift of 20+10-9 (95% CL) for a range
of ionization scenarios. This early reionization is incompatible with the
presence of a significant warm dark matter density. The age of the best-fit
universe is 13.7 +/- 0.2 Gyr old. Decoupling was 379+8-7 kyr after the Big Bang
at a redshift of 1089 +/- 1. The thickness of the decoupling surface was dz=195
+/- 2. The matter density is Omega_m h^2 = 0.135 +0.008 -0.009, the baryon
density is Omega_b h^2 = 0.0224 +/- 0.0009, and the total mass-energy of the
universe is Omega_tot = 1.02 +/- 0.02. The spectral index of scalar
fluctuations is fit as n_s = 0.93 +/- 0.03 at wavenumber k_0 = 0.05 Mpc^-1,
with a running index slope of dn_s/d ln k = -0.031 +0.016 -0.018 in the
best-fit model. This flat universe model is composed of 4.4% baryons, 22% dark
matter and 73% dark energy. The dark energy equation of state is limited to
w<-0.78 (95% CL). Inflation theory is supported with n_s~1, Omega_tot~1,
Gaussian random phases of the CMB anisotropy, and superhorizon fluctuations. An
admixture of isocurvature modes does not improve the fit. The tensor-to-scalar
ratio is r(k_0=0.002 Mpc^-1)<0.90 (95% CL).


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Foreground Emission

abstract:
  Full sky maps are made in five microwave frequency bands to separate the
temperature anisotropy of the CMB from foreground emission. We define masks
that excise regions of high foreground emission. The effectiveness of template
fits to remove foreground emission from the WMAP data is examined. These
efforts result in a CMB map with minimal contamination and a demonstration that
the WMAP CMB power spectrum is insensitive to residual foreground emission. We
construct a model of the Galactic emission components. We find that the Milky
Way resembles other normal spiral galaxies between 408 MHz and 23 GHz, with a
synchrotron spectral index that is flattest (beta ~ -2.5) near star-forming
regions, especially in the plane, and steepest (beta ~ -3) in the halo. The
significant synchrotron index steepening out of the plane suggests a diffusion
process in which the halo electrons are trapped in the Galactic potential long
enough to suffer synchrotron and inverse Compton energy losses and hence a
spectral steepening. The synchrotron index is steeper in the WMAP bands than in
lower frequency radio surveys, with a spectral break near 20 GHz to beta < -3.
The modeled thermal dust spectral index is also steep in the WMAP bands, with
beta ~ 2.2. Microwave and H alpha measurements of the ionized gas agree.
Spinning dust emission is limited to < ~5% of the Ka-band foreground emission.
A catalog of 208 point sources is presented. Derived source counts suggest a
contribution to the anisotropy power from unresolved sources of (15.0 +- 1.4)
10^{-3} microK^2 sr at Q-band and negligible levels at V-band and W-band.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Determination of Cosmological Parameters

abstract:
  WMAP precision data enables accurate testing of cosmological models. We find
that the emerging standard model of cosmology, a flat Lambda-dominated universe
seeded by nearly scale-invariant adiabatic Gaussian fluctuations, fits the WMAP
data. With parameters fixed only by WMAP data, we can fit finer scale CMB
measurements and measurements of large scle structure (galaxy surveys and the
Lyman alpha forest). This simple model is also consistent with a host of other
astronomical measurements. We then fit the model parameters to a combination of
WMAP data with other finer scale CMB experiments (ACBAR and CBI), 2dFGRS
measurements and Lyman alpha forest data to find the model's best fit
cosmological parameters: h=0.71+0.04-0.03, Omega_b h^2=0.0224+-0.0009, Omega_m
h^2=0.135+0.008-0.009, tau=0.17+-0.06, n_s(0.05/Mpc)=0.93+-0.03, and
sigma_8=0.84+-0.04. WMAP's best determination of tau=0.17+-0.04 arises directly
from the TE data and not from this model fit, but they are consistent. These
parameters imply that the age of the universe is 13.7+-0.2 Gyr. The data favors
but does not require a slowly varying spectral index. By combining WMAP data
with other astronomical data sets, we constrain the geometry of the universe,
Omega_tot = 1.02 +- 0.02, the equation of state of the dark energy w < -0.78
(95% confidence limit assuming w >= -1), and the energy density in stable
neutrinos, Omega_nu h^2 < 0.0076 (95% confidence limit). For 3 degenerate
neutrino species, this limit implies that their mass is less than 0.23 eV (95%
confidence limit). The WMAP detection of early reionization rules out warm dark
matter.


title: GRB Energetics and the GRB Hubble Diagram: Promises and Limitations

abstract:
  We present a complete sample of 29 GRBs for which it has been possible to
determine temporal breaks (or limits) from their afterglow light curves. We
interpret these breaks within the framework of the uniform conical jet model,
incorporating realistic estimates of the ambient density and propagating error
estimates on the measured quantities. In agreement with our previous analysis
of a smaller sample, the derived jet opening angles of those 16 bursts with
redshifts result in a narrow clustering of geometrically-corrected gamma-ray
energies about E_gamma = 1.33e51 erg; the burst-to-burst variance about this
value is a factor of 2.2. Despite this rather small scatter, we demonstrate in
a series of GRB Hubble diagrams, that the current sample cannot place
meaningful constraints upon the fundamental parameters of the Universe. Indeed
for GRBs to ever be useful in cosmographic measurements we argue the necessity
of two directions. First, GRB Hubble diagrams should be based upon fundamental
physical quantities such as energy, rather than empirically-derived and
physically ill-understood distance indicators. Second, a more homogeneous set
should be constructed by culling sub-classes from the larger sample. These
sub-classes, though now first recognizable by deviant energies, ultimately must
be identifiable by properties other than those directly related to energy. We
identify a new sub-class of GRBs (``f-GRBs'') which appear both underluminous
by factors of at least 10 and exhibit a rapid fading at early times. About
10-20% of observed long-duration bursts appear to be f-GRBs.


title:
VLBI Polarimetry of 177 Sources from the Caltech-Jodrell Bank
  Flat-spectrum Survey

abstract:
  We present VLBA observations and a statistical analysis of 5 GHz VLBI
polarimetry data from 177 sources in the Caltech-Jodrell Bank flat-spectrum
(CJF) survey. The CJF survey, a complete, flux-density-limited sample of 293
extragalactic radio sources, gives us the unique opportunity to compare a broad
range of source properties for quasars, galaxies and BL Lacertae objects. We
focus primarily on jet properties, specifically the correlation between the jet
axis angle and the polarization angle in the core and jet. A strong correlation
is found for the electric vector polarization angle in the cores of quasars to
be perpendicular to the jet axis. Contrary to previous claims, no correlation
is found between the jet polarization angle and the jet axis in either quasars
or BL Lac objects. With this large, homogeneous sample we are also able to
investigate cosmological issues and AGN evolution.


title: Lyman Break Galaxies and the Star Formation Rate of the Universe at z~6

abstract:
  We determine the space density of UV-luminous star-burst galaxies at z~6
using deep HST ACS SDSS-i' (F775W) and SDSS-z' (F850LP) and VLT ISAAC J and K_s
band imaging of the Chandra Deep Field South. We find 8 galaxies and one star
with (i'-z')>1.5 to a depth of z'{AB}= 25.6 (an 8-sigma detection in each of
the 3 available ACS epochs). This corresponds to an unobscured star formation
rate of ~15M_sun/yr/h{70}^2 at z=5.8, equivalent to L* for the Lyman break
population at z =3-4 (Omega_{Lambda}=0.7, Omega_M=0.3). We are sensitive to
star forming galaxies at 5.6<z<7.0 with an effective comoving volume of
\~1.8x10^5 Mpc^3/h{70}^3 after accounting for incompleteness at the higher
redshifts due to luminosity bias. This volume should encompass the primeval
sub-galactic scale fragments of the progenitors of about a thousand L* galaxies
at the current epoch. We determine a volume-averaged global star formation rate
of (6.7 +/- 2.7)x10^{-4}h{70}M_sun/yr/Mpc^3 at z~6 from rest-frame UV selected
star-bursts at the bright end of the luminosity function: this is a lower limit
because of dust obscuration and galaxies below our sensitivity limit. This
measurement shows that at z~6 the star formation density at the bright end is a
factor of ~6 times less than that determined by Steidel et al. (1999) for a
comparable sample of UV selected galaxies at z=3-4, and so extends our
knowledge of the star formation history of the Universe to earlier times than
previous work and into the epoch where reionization may have occurred.


title:
Wilkinson Microwave Anisotropy Probe (WMAP) First Year Observations: TE
  Polarization

abstract:
  The Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the full sky in
Stokes I, Q, and U parameters at frequencies 23, 33, 41, 61, and 94 GHz. We
detect correlations between the temperature and polarization maps significant
at more than 10 standard deviations. The correlations are present in all WMAP
frequency bands with similar amplitude from 23 to 94 GHz, and are consistent
with a superposition of a CMB signal with a weak foreground. The fitted CMB
component is robust against different data combinations and fitting techniques.
On small angular scales theta < 5 deg, the WMAP data show the
temperature-polarization correlation expected from adiabatic perturbations in
the temperature power spectrum. The data for l > 20 agree well with the signal
predicted solely from the temperature power spectra, with no additional free
parameters. We detect excess power on large angular scales (theta > 10 deg)
compared to predictions based on the temperature power spectra alone. The
excess power is well described by reionization at redshift 11 < z_r < 30 at 95%
confidence, depending on the ionization history. A model-independent fit to
reionization optical depth yields results consistent with the best-fit
LambdaCDM model, with best fit value tau = 0.17 +- 0.04 at 68% confidence,
including systematic and foreground uncertainties. This value is larger than
expected given the detection of a Gunn-Peterson trough in the absorption
spectra of distant quasars, and implies that the universe has a complex
ionization history: WMAP has detected the signal from an early epoch of
reionization.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Beam Profiles and Window Functions

abstract:
  Knowledge of the beam profiles is of critical importance for interpreting
data from cosmic microwave background experiments. In this paper, we present
the characterization of the in-flight optical response of the WMAP satellite.
The main beam intensities have been mapped to < -30 dB of their peak values by
observing Jupiter with the satellite in the same observing mode as for CMB
observations. The beam patterns closely follow the pre-launch expectations. The
full width at half maximum is a function of frequency and ranges from 0.82
degrees at 23 GHz to 0.21 degrees at 94 GHz; however, the beams are not
Gaussian. We present: (a) the beam patterns for all ten differential
radiometers and show that the patterns are substantially independent of
polarization in all but the 23 GHz channel; (b) the effective symmetrized beam
patterns that result from WMAP's compound spin observing pattern; (c) the
effective window functions for all radiometers and the formalism for
propagating the window function uncertainty; and (d) the conversion factor from
point source flux to antenna temperature. A summary of the systematic
uncertainties, which currently dominate our knowledge of the beams, is also
presented. The constancy of Jupiter's temperature within a frequency band is an
essential check of the optical system. The tests enable us to report a
calibration of Jupiter to 1-3% accuracy relative to the CMB dipole.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Galactic Signal Contamination from Sidelobe Pickup

abstract:
  Since the Galactic center is ~1000 times brighter than fluctuations in the
Cosmic Microwave Background (CMB), CMB experiments must carefully account for
stray Galactic pickup. We present the level of contamination due to sidelobes
for the year one CMB maps produced by the WMAP observatory. For each
radiometer, full 4 pi sr antenna gain patterns are determined from a
combination of numerical prediction, ground-based and space-based measurements.
These patterns are convolved with the WMAP year one sky maps and observatory
scan pattern to generate expected sidelobe signal contamination, for both
intensity and polarized microwave sky maps. Outside of the Galactic plane, we
find rms values for the expected sidelobe pickup of 15, 2.1, 2.0, 0.3, 0.5 uK
for K, Ka, Q, V, and W bands respectively. Except at K band, the rms polarized
contamination is <<1 uK. Angular power spectra of the Galactic pickup are
presented.


title: Current Challenges Facing Planet Transit Surveys

abstract:
  The initial task that confronted extrasolar-planet transit surveys was to
monitor enough stars with sufficient photometric precision and complete phase
coverage. Numerous searches have been pursued over the last few years. Among
these projects are shallow, intermediate, and deep surveys of the Galactic
plane, and monitoring of open clusters, and a globular cluster. These projects
have all defeated the initial technical challenge, but a new obstacle has risen
in its place: Single-color photometric time series are not sufficient to
identify uniquely transiting planet systems, as eclipsing binary stars can
mimic the signal. Multicolor photometric time series and multi-epoch
spectroscopic monitoring are required to cull the list of candidates prior to
high-precision radial velocity monitoring. I also discuss the prospects for
detecting another transiting system among the planets found by the
radial-velocity method, as well as review the recent announcement of
OGLE-TR-56b, the first extrasolar planet detected by the transit method.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Angular Power Spectrum

abstract:
  We present the angular power spectrum derived from the first-year Wilkinson
Microwave Anisotropy Probe (WMAP) sky maps. We study a variety of power
spectrum estimation methods and data combinations and demonstrate that the
results are robust. The data are modestly contaminated by diffuse Galactic
foreground emission, but we show that a simple Galactic template model is
sufficient to remove the signal. Point sources produce a modest contamination
in the low frequency data. After masking ~700 known bright sources from the
maps, we estimate residual sources contribute ~3500 uK^2 at 41 GHz, and ~130
uK^2 at 94 GHz, to the power spectrum l*(l+1)*C_l/(2*pi) at l=1000. Systematic
errors are negligible compared to the (modest) level of foreground emission.
Our best estimate of the power spectrum is derived from 28 cross-power spectra
of statistically independent channels. The final spectrum is essentially
independent of the noise properties of an individual radiometer. The resulting
spectrum provides a definitive measurement of the CMB power spectrum, with
uncertainties limited by cosmic variance, up to l~350. The spectrum clearly
exhibits a first acoustic peak at l=220 and a second acoustic peak at l~540 and
it provides strong support for adiabatic initial conditions. Kogut et al.
(2003) analyze the C_l^TE power spectrum, and present evidence for a relatively
high optical depth, and an early period of cosmic reionization. Among other
things, this implies that the temperature power spectrum has been suppressed by
\~30% on degree angular scales, due to secondary scattering.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Parameter Estimation Methodology

abstract:
  We describe our methodology for comparing the WMAP measurements of the cosmic
microwave background (CMB) and other complementary data sets to theoretical
models. The unprecedented quality of the WMAP data, and the tight constraints
on cosmological parameters that are derived, require a rigorous analysis so
that the approximations made in the modeling do not lead to significant biases.
We describe our use of the likelihood function to characterize the statistical
properties of the microwave background sky. We outline the use of the Monte
Carlo Markov Chains to explore the likelihood of the data given a model to
determine the best fit cosmological parameters and their uncertainties. We add
to the WMAP data the l>~700 CBI and ACBAR measurements of the CMB, the galaxy
power spectrum at z~0 obtained from the 2dF galaxy redshift survey (2dFGRS),
and the matter power spectrum at z~3 as measured with the Ly alpha forest.
These last two data sets complement the CMB measurements by probing the matter
power spectrum of the nearby universe. Combining CMB and 2dFGRS requires that
we include in our analysis a model for galaxy bias, redshift distortions, and
the non-linear growth of structure. We show how the statistical and systematic
uncertainties in the model and the data are propagated through the full
analysis.


title:
The Effect of Neutron Star Binding Energy on
  Gravitational-Radiation-Driven Mass-Transfer Binaries

abstract:
  In a relativistic model of a neutron star, the star's mass is less than the
mass of the individual component baryons. This is due to the fact that the
star's negative binding energy makes a contribution to the star's total energy
and its mass. A consequence of this relativistic mass deficit is that a neutron
star that is accreting matter increases its mass at a rate which is slower than
the mass of a baryon times the rate that baryons are accreted. This difference
in the rate of change of the masses has a simple relation with the star's
gravitational redshift. We show that this effect has the potential to be
observed in binaries where the mass transfer is driven by angular momentum
losses from the gravitational radiation emitted by the binary motion.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Interpretation of the TT and TE Angular Power Spectrum Peaks

abstract:
  The CMB has distinct peaks in both its temperature angular power spectrum
(TT) and temperature-polarization cross-power spectrum (TE). From the WMAP data
we find the first peak in the temperature spectrum at l = 220.1 +- 0.8 with an
amplitude of 74.7 +- 0.5 microK; the first trough at l = 411.7 +- 3.5 with an
amplitude of 41.0 +- 0.5 microK; and the second peak at l = 546 +- 10 with an
amplitude of 48.8 +- 0.9 microK. The TE spectrum has an antipeak at l = 137 +-
9 with a cross-power of -35 +- 9 microK^2, and a peak at l = 329 +- 19 with
cross-power 105 +- 18 microK^2. All uncertainties are 1 sigma and include
calibration and beam errors. An intuition for how the data determine the
cosmological parameters may be gained by limiting one's attention to a subset
of parameters and their effects on the peak characteristics. We interpret the
peaks in the context of a flat adiabatic LambdaCDM model with the goal of
showing how the cosmic baryon density, Omega_b h^2, matter density, Omega_m
h^2, scalar index, n_s, and age of the universe are encoded in their positions
and amplitudes. To this end, we introduce a new scaling relation for the TE
antipeak-to-peak amplitude ratio and recompute known related scaling relations
for the TT spectrum in light of the WMAP data. From the scaling relations, we
show that WMAP's tight bound on Omega_b h^2 is intimately linked to its robust
detection of the first and second peaks of the TT spectrum.


title:
Palomar/Las Campanas Imaging Atlas of Blue Compact Dwarf galaxies: I.
  Images and integrated photometry

abstract:
  We present B, R, and Halpha images for a total of 114 nearby galaxies
(v_helio<4000km/s) that, with exception of 9 objects, are classified as Blue
Compact Dwarfs (BCDs). BR integrated magnitudes, Halpha fluxes and Halpha
equivalent widths for all the objects in the sample are presented. A new set of
quantitative, observational criteria for a galaxy to be classified as a BCD is
proposed. These criteria include a limit on the K-band luminosity (i.e. stellar
mass; M_K>-21mag), peak surface brightness (mu_B,peak<22mag/arcsec^2), and
color at the peak surface brightness (mu_B,peak-mu_R,peak<~1). Halpha emission
is detected in all but three sample galaxies. Typical color, absolute
magnitude, and Halpha luminosity are (B-R)=0.7+/-0.3mag, M_B=-16.1+/-1.4mag,
and log(L_Halpha)=40.0+/-0.6(erg/s). Galaxies morphologically classified as nE
and iE BCDs within our sample show lower Halpha equivalent widths and redder
colors, on average, than the iI and i0-type BCDs. For most of the galaxies the
presence of an evolved stellar population is required to explain their observed
properties; only the most metal-poor BCDs (e.g. IZw18, Tol65) are still
compatible with a pure, young burst. The flux-calibrated and WCS-compliant
images in this Atlas are individually available through the NASA/IPAC
Extragalactic Database (NED) image server and collectively through a dedicated
web page at http://nedwww.ipac.caltech.edu/level5/Sept02/Palco_BCD/frames.html


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Data Processing Methods and Systematic Errors Limits

abstract:
  We describe the calibration and data processing methods used to generate
full-sky maps of the cosmic microwave background (CMB) from the first year of
Wilkinson Microwave Anisotropy Probe (WMAP) observations. Detailed limits on
residual systematic errors are assigned based largely on analyses of the flight
data supplemented, where necessary, with results from ground tests. The data
are calibrated in flight using the dipole modulation of the CMB due to the
observatory's motion around the Sun. This constitutes a full-beam calibration
source. An iterative algorithm simultaneously fits the time-ordered data to
obtain calibration parameters and pixelized sky map temperatures. The noise
properties are determined by analyzing the time-ordered data with this sky
signal estimate subtracted. Based on this, we apply a pre-whitening filter to
the time-ordered data to remove a low level of 1/f noise. We infer and correct
for a small ~1% transmission imbalance between the two sky inputs to each
differential radiometer, and we subtract a small sidelobe correction from the
23 GHz (K band) map prior to further analysis. No other systematic error
corrections are applied to the data. Calibration and baseline artifacts,
including the response to environmental perturbations, are negligible.
Systematic uncertainties are comparable to statistical uncertainties in the
characterization of the beam response. Both are accounted for in the covariance
matrix of the window function and are propagated to uncertainties in the final
power spectrum. We characterize the combined upper limits to residual
systematic uncertainties through the pixel covariance matrix.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Tests of Gaussianity

abstract:
  We present limits to the amplitude of non-Gaussian primordial fluctuations in
the WMAP 1-year cosmic microwave background sky maps. A non-linear coupling
parameter, f_NL, characterizes the amplitude of a quadratic term in the
primordial potential. We use two statistics: one is a cubic statistic which
measures phase correlations of temperature fluctuations after combining all
configurations of the angular bispectrum. The other uses the Minkowski
functionals to measure the morphology of the sky maps. Both methods find the
WMAP data consistent with Gaussian primordial fluctuations and establish
limits, -58<f_NL<134, at 95% confidence. There is no significant frequency or
scale dependence of f_NL. The WMAP limit is 30 times better than COBE, and
validates that the power spectrum can fully characterize statistical properties
of CMB anisotropy in the WMAP data to high degree of accuracy. Our results also
validate the use of a Gaussian theory for predicting the abundance of clusters
in the local universe. We detect a point-source contribution to the bispectrum
at 41 GHz, b_src = (9.5+-4.4) X 1e-5 uK^3 sr^2, which gives a power spectrum
from point sources of c_src = (15+-6) X 1e-3 uK^2 sr in thermodynamic
temperature units. This value agrees well with independent estimates of source
number counts and the power spectrum at 41 GHz, indicating that b_src directly
measures residual source contributions.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  On-Orbit Radiometer Characterization

abstract:
  The WMAP satellite has completed one year of measurements of the Cosmic
Microwave Background (CMB) radiation using 20 differential
high-electron-mobility-transistor (HEMT) based radiometers. All the radiometers
are functioning nominally, and characterizations of the on-orbit radiometer
performance are presented, with an emphasis on properties that are required for
the production of sky maps from the time ordered data. A radiometer gain model,
used to smooth and interpolate the CMB dipole gain measurements is also
presented. No degradation in the sensitivity of any of the radiometers has been
observed during the first year of observations.


title:
First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Implications for Inflation

abstract:
  We confront predictions of inflationary scenarios with the WMAP data, in
combination with complementary small-scale CMB measurements and large-scale
structure data. The WMAP detection of a large-angle anti-correlation in the
temperature--polarization cross-power spectrum is the signature of adiabatic
superhorizon fluctuations at the time of decoupling. The WMAP data are
described by pure adiabatic fluctuations: we place an upper limit on a
correlated CDM isocurvature component. Using WMAP constraints on the shape of
the scalar power spectrum and the amplitude of gravity waves, we explore the
parameter space of inflationary models that is consistent with the data. We
place limits on inflationary models; for example, a minimally-coupled lambda
phi^4 is disfavored at more than 3-sigma using WMAP data in combination with
smaller scale CMB and large scale structure survey data. The limits on the
primordial parameters using WMAP data alone are: n_s(k_0=0.002
Mpc^{-1})=1.20_{-0.11}^{+0.12}, dn/dlnk=-0.077^{+0.050}_{- 0.052}, A(k_0=0.002
Mpc}^{-1})=0.71^{+0.10}_{-0.11} (68% CL), and r(k_0=0.002 Mpc^{-1})<1.28 (95%
CL).


title: The Phenomena of High Energy Astrophysics

abstract:
  A brief summary of some highlights in the study of high energy astrophysical
sources over the past decade is presented. It is argued that the great progress
that has been made derives largely from the application of new technology to
observation throughout all of the electromagnetic and other spectra and that,
on this basis, the next decade should be even more exciting. However, it is
imperative to observe cosmic sources throughout these spectra in order to
obtain a full understanding of their properties. In addition, it is necessary
to learn the universal laws that govern the macroscopic and the microscopic
behavior of cosmic plasma over a great range of physical conditions by
combining observations of different classes of source. These two injunctions
are illustrated by discussions of cosmology, hot gas, supernova remnants and
explosions, neutron stars, black holes and ultrarelativistic outflows. New
interpreations of the acceleration of Galactic cosmic rays, the cooling of hot
gas in rich clusters and the nature of ultrarelativistic outflows are outlined.
The new frontiers of VHE $\gamma$-ray astronomy, low frequency radio astronomy,
neutrino astronomy, UHE cosmic ray physics and gravitational wave astronomy are
especially promising.


title:
Interferometric Detection of Linear Polarization from Sagittarius A* at
  230 GHz

abstract:
  We measured the linear polarization of Sagittarius A* to be 7.2 +/- 0.6 % at
230 GHzusing the BIMA array with a resolution of 3.6 x 0.9 arcsec. This
confirms the previously reported detection with the JCMT 14-m antenna. Our high
resolution observations demonstrate that the polarization does not arise from
dust but from a synchrotron source associated with Sgr A*. We see no change in
the polarization position angle and only a small change in the polarization
fraction in four observations distributed over 60 days. We find a position
angle 139 +/- 4 degrees that differs substantially from what was found in
earlier JCMT observations at the same frequency. Polarized dust emission cannot
account for this discrepancy leaving variability and observational error as the
only explanations. The BIMA observations alone place an upper limit on the
magnitude of the rotation measure of 2 x 10^6 rad m^-2. These new observations
when combined with the JCMT observations at 150, 375 and 400 GHz suggest RM
=-4.3 +/- 0.1 x 10^5 rad m^-2. This RM may be caused by an external Faraday
screen. Barring a special geometry or a high number of field reversals, this RM
rules out accretion rates greater than ~ 10^-7 M_sun y^-1. This measurement is
inconsistent with high accretion rates necessary in standard advection
dominated accretion flow and Bondi-Hoyle models for Sgr A*. It argues for low
accretion rates as a major factor in the overall faintness of Sgr A*.


title: Linear and Circular Polarization from Sagittarius A* and M81*

abstract:
  We describe recent results for Sgr A*, M81* and other low luminosity active
galactic nuclei. We have conducted linear and circular polarimetry over a
frequency range of 1.4 to 230 GHz and detected a variety of phenomena. The
polarization properties of the studied sources are substantially different from
higher powered AGN. In the case of Sgr A*, we are able to eliminate ADAFs and
Bondi-Hoyle flows as possible models based on mm $\lambda$ polarimetry. Our
success with Sgr A* demonstrates that we can learn about the nature of
accretion and outflow in these sources with unprecedented detail. We may also
develop probes of general relativity in the strong-field limit.


title: X-ray astronomy in the new Millenium. A Summary

abstract:
  Recent X-ray observations have had a major impact on topics ranging from
protostars to cosmology. They have also drawn attention to important and
general physical processes that currently limit our understanding of thermal
and nonthermal X-ray sources. These include unmeasured atomic astrophysics data
(wavelengths, oscillator strengths etc.), basic hydromagnetic processes (e.g.
shock structure, reconnection), plasma processes (such as electron-ion
equipartition and heat conduction) and radiative transfer (in disks and
accretion columns). Progress on these problems will probably come from
integrative studies that draw upon observations, throughout the electromagnetic
spectrum, of different classes of source. X-ray observations are also giving a
new perspective on astronomical subjects, like the nature of galactic nuclei
and the evolution of stellar populations. They are contributing to answering
central cosmological questions including the measurement of the matter content
of the universe, understanding its overall luminosity density, describing its
chemical evolution and locating the first luminous objects. X-ray astronomy has
a healthy future with several international space missions under construction
and in development.


title: Resolved Jets and Long-Period Black Hole X-ray Novae

abstract:
  In this brief note we point out that the four spatially resolved relativistic
jets among the 14 dynamically confirmed black hole X-ray novae are all in
systems with long orbital periods. Many shorter period systems show transient
radio outbursts which are attributed to jets, but these jets have not been
spatially resolved. Super-Eddington accretion has been suggested as a
requirement for jet formation and may be consistent with our compilation of
luminosities, but some super-Eddington outbursts did not form spatially
resolved jets. We speculate that some as yet unknown process (or combination of
processes) favors formation of substantially larger jets in long period
systems. Two short period systems show evidence for extent, but have not been
resolved into multiple components as the long period systems have.


title:
Cosmic Rays and Neutrinos from GRBs: Predictions versus Acceleration
  Modeling

abstract:
  The paper is devoted to the analysis of Fermi acceleration of protons in GRBs
and its neutrino signature. We have compared the consequences of Bohm scaling
and those of a Kolmogorov scaling, the latter being more reliable. The
predictions about the energy limitation of UHE-protons by the various losses
and the neutrino emissions turn out to be very sensitive to these scalings. We
consider Kolmogorov scaling as the most realistic and predict a reasonable
pp-neutrino emission around 100 GeV at the end of the radiative stage of the
fireball expansion, for a large number of GRBs pending on their baryonic load.
A second p$\gamma$-neutrino emission is expected with the acceleration of
protons in the radiation free stage, but with a synchrotron loss limitation
immediately followed by a severe expansion loss limitation. According to the
Kolmogorov scaling, the protons could not reach the UHE-range. Anyway the large
possibility of a two component neutrino emission would be an interesting clue
of cosmic ray physics.


title: Binary evolution models with rotation

abstract:
  We discuss the first available binary evolution models which include
up-to-date rotational physics for both components, as well as angular momentum
accretion and spin-orbit coupling. These models allow a self-consistent
computation of the mass transfer efficiency during Roche-lobe overflow phases,
and a determination of the transition from quasi-conservative to
non-conservative evolution. Applications to massive binary systems lead to
predictions for the spin rates of compact objects in binaries, and for the
occurrence of gamma-ray bursts from collapsars in binaries. Rotational effects
in accreting white dwarfs are found to stabilise the shell burning and decrease
the carbon abundance in progenitor models for Chandrasekhar-mass Type Ia
supernovae, and to potentially avoid a detonation of the white dwarf within the
sub-Chandrasekhar mass scenario.


title: Nova nucleosynthesis and Galactic evolution of the CNO isotopes

abstract:
  We study the role played both by novae and single stars in enriching the ISM
of the Galaxy with CNO group nuclei, in the framework of a detailed successful
model for the chemical evolution of both the Galactic halo and disc. Once all
the nucleosynthesis sources of CNO elements are taken into account, we conclude
that 13C, 15N and 17O are likely to have both a primary and a secondary origin,
in contrast to previous beliefs. Given the uncertainties still present in the
computation of theoretical stellar yields, our results can be used to put
constraints on stellar evolution and nucleosynthesis models.


title:
Variability of the Halpha emission of Cygnus X-1 and its connection with
  the soft X-ray radiation

abstract:
  High-resolution Halpha monitoring of Cyg X-1, HD226868 was carried out during
1996-2002 and the resultant spectra analysed in conjunction with 1.5-12 keV
X-ray monitoring. We demonstrate that the Halpha line-profiles have complex
variability on different timescales, controlled in particular by the orbital
period and the focused wind model of mass loss. We find that long-term
variability of the mass loss by the supergiant and short-term variability due
to clumpy structure of the stellar wind dominate during the low/hard X-ray
state and that X-ray photoionization has a relatively small influence on the
line-profile shape and EW variability. During the high/soft X-ray state and
flaring the effect of photoionization the line-profile and EW of Halpha
increases but is still unable to describe the loose anti-correlation between EW
and the low energy X-ray emission. We propose that variability of the mass loss
by the supergiant can change wind velocities in the Stromgren zone around the
accretion disc of the secondary, leading to an increase in accretion rate
through the disc.


title: Models of the Accretion Spots in Magnetic Cataclysmic Variables

abstract:
  The structure of the near-polar accretion spots on accreting magnetic white
dwarfs has been studied theoretically and observationally in numerous papers
over the last decade. Detailed treatments are available for the regime of low
mass flux, usually termed the bombardment case, and for higher mass fluxes
which create a strong shock standing above the photosphere of the white dwarf.
No general treatment is so far available for the case of shocks buried deep in
the photosphere. I review the theoretical foundations, present some
applications of theory, and discuss in short the open questions which still
need to be addressed.


title: The Synoptic Swift Synergy -- Catching Gamma-Ray Bursts Before They Fly

abstract:
  The advent of large panoramic photometric surveys of the sky offers the
possibly of exploring the association of gamma-ray bursts (GRBs) with
supernovae. To date, a few gamma-ray bursts have been connected possibly with
supernovae: GRB 980425 -- SN 1998bw, GRB 011121 -- SN 2001ke, GRB 970228 and
GRB 980326. A combination of a large detection rate of GRBs and rapid coverage
of a large portion of the sky to faint magnitude limits offers the possibility
of detecting a supernova preceding an associated GRB or at least placing limits
on the rate of association between these two phenomena and the time delay
between them. This would provide important constraints on theoretical models
for gamma-ray bursts.


title: The emission distribution of RR Pictoris

abstract:
  We present time-resolved optical spectroscopy of the old nova RR Pic. Two
emission lines (Halpha and He I) are present in the observed part of the
spectrum and both show strong variability. Halpha has been used for Doppler
tomography in order to map the emission distribution in this system for the
first time. The resulting map shows the emission from the disc as well as two
additional emission sources on the leading and trailing side of the disc.
Furthermore we find evidence for the presence of either a disc-overflow or an
asymmetric outflow from the binary with velocities up to +- 1200km/s. The
origin of the outflow would be the emission source on the leading side of the
accretion disc.


title: X-ray absorption via K-alpha resonance complexes in oxygen ions

abstract:
  The K-alpha resonance complexes in oxygen ions O I - O VI are theoretically
computed and resonance oscillator strengths and wavelengths are presented. The
highly resolved photoionization cross sections, with relativistic fine
structure, are computed in the coupled channel approximation using the
Breit-Pauli R-matrix method. A number of strong K-alpha resonances are found to
be appreciable, with resonance oscillator strengths f_r > 0.1. The K-alpha
resonance wavelengths of O I-O VI lie in a relatively narrow wavelength range
22 - 23.5 A, and the X-ray opacity in this region should therefore be
significantly affected by K --> L transitions in oxygen. The results should be
useful in the interpretation of soft X-ray spectra observed from Chandra and
XMM-Newton.


title:
Non-spherical Core Collapse Supernovae I. Neutrino-Driven Convection,
  Rayleigh-Taylor Instabilities, and the Formation and Propagation of Metal
  Clumps

abstract:
  Two-dimensional simulations of a Type II and a Type Ib-like supernova
explosion are presented that encompass shock revival by neutrino heating,
neutrino-driven convection, explosive nucleosynthesis, the growth of
Rayleigh-Taylor instabilities, and the propagation of newly formed metal clumps
through the exploding star. In both cases we find very high Ni56 velocities of
17000 km/s shortly after shock-revival, and a complete fragmentation of the
progenitor's metal core within the first few minutes after core bounce, due to
the growth of Rayleigh-Taylor instabilities at the Si/O and (C+O)/He
composition interfaces. This leads to the formation of high-velocity,
metal-rich clumps which eventually decouple from the flow and move
ballistically through the ejecta. Maximum final metal velocities of 3500-5500
km/s and 1200 km/s are obtained for the Type Ib model and the Type II model,
respectively. The low maximum metal velocities in the Type II model, which are
significantly smaller than those observed in SN 1987A, are due to the massive
hydrogen envelope of the progenitor. The envelope forces the supernova shock to
decelerate strongly, leaving behind a reverse shock below the He/H interface,
which interacts with the clumps and slows them down significantly. This reverse
shock is absent in the Type Ib-like model. The latter is in fairly good
agreement with observations of Type Ib supernovae. In addition, in this case
the pattern of clump formation in the ejecta is correlated with the convective
pattern prevailing during the shock-revival phase. This might be used to deduce
observational constraints for the dynamics during this early phase of the
evolution, and the role of neutrino heating in initiating the explosion.


title: Ultra-Short Period Double-Degenerate Binaries

abstract:
  We review the current observational status of the ROSAT sources RX
J1914.4+2456 and RX J0806.3+1527, and the evidence that these are ultra-short
period (<10min) binary systems. We argue that an Intermediate Polar
interpretation can be ruled out, that they are indeed compact binaries with a
degenerate secondary, and that the period seen in the X-ray and optical is the
orbital period. A white dwarf primary is preferred, but a neutron star cannot
be excluded. We examine the capability of the three current double-degenerate
models (Polar, Direct Accretor and Electric Star) to account for the
observational characteristics of these systems. All models have difficulties
with some aspects of the observations, but none can be excluded with confidence
at present. The Electric Star model provides the best description, but the
lifetime of this phase requires further investigation. These ultra-short period
binaries will be strong gravitational wave emitters in the LISA bandpass, and
because of their known source properties will be important early targets for
gravitational wave studies.


title: Spectroscopic Identification of the Infrared Counterpart to GX5-1

abstract:
  Using CGS4 on UKIRT, we have obtained a 1.95-2.45 micron infrared spectrum of
the primary candidate counterpart to the bright Z LMXB GX5-1. IR photometry by
Naylor, Charles, & Longmore (1992) and the astrometry of Jonker et al. (2000)
had previously identified this star as the most likely counterpart to GX5-1.
The spectrum presented here clearly shows Brackett gamma and He lines in
emission, for the first time confirming the identity of the counterpart.
Similar to our previous spectroscopy of the Z source LMXBs Sco X-1 and Sco X-2
(Bandyopadhyay et al. 1999), the K-band spectrum of GX5-1 shows emission lines
only. We briefly discuss the implications of this spectrum for the nature of
the Z sources.


title: The HRX-BL Lac sample - evolution of BL Lac objects

abstract:
  The unification of X-ray and radio selected BL Lacs has been an outstanding
problem in the blazar research in the past years. Recent investigations have
shown that the gap between the two classes can be filled with intermediate
objects and that apparently all differences can be explained by mutual shifts
of the peak frequencies of the synchrotron and inverse Compton component of the
emission. We study the consequences of this scheme using a new sample of X-ray
selected BL Lac objects comprising 104 objects with z<0.9 and a mean redshift
z=0.34. 77 BL Lacs, of which the redshift could be determined for 64 (83%)
objects, form a complete sample. The new data could not confirm our earlier
result, drawn from a subsample, that the negative evolution vanishes below a
synchrotron peak frequency log (peak-frequency) = 16.5. The complete sample
shows negative evolution at the 2 sigma level (<V_e/V_a> = 0.42 +- 0.04). We
conclude that the observed properties of the HRX BL Lac sample show typical
behaviour for X-ray selected BL Lacs. They support an evolutionary model, in
which flat-spectrum radio quasars (FSRQ) with high energetic jets evolve
towards low frequency peaked (mostly radio-selected) BL Lac objects and later
on to high frequency peaked (mostly X-ray selected) BL Lacs.


title: Optical Spectroscopy of GX 339-4 - Paper I: Orbital Modulation

abstract:
  Optical spectroscopic observations of GX 339-4 were carried out between 1998
May (X-ray high state) and 1999 May (X-ray low state) over 7 epochs. The
equivalent width of Halpha increased during the high state then decreased
during the low state. The equivalent width of HeII 4686 decreased over both
states. The full-width half-maximum of Halpha, Hbeta, HeII 4686 and the Bowen
Blend increased from 1998 to 1999 indicating that the emission line regions
moved closer to the compact object. Hbeta shows a redshifted absorption feature
at 4880 angstroms at all epochs. This line remains unidentified. Analysis of
individual spectra from 1998 May 28-31 show modulation of the radial
velocities, equivalent width and V/R ratios of Halpha on the 14.86 hour orbital
period. The equivalent width of HeII 4686 also varies on the orbital period.
This is the first time since the study of Calanan et al. (1992) that
spectroscopic data has confirmed the orbital period. The semi-amplitude of the
Halpha radial velocities is K_1 = 14 km/s. Hence the mass function = 2 x
10^(-4) Msun.


title: Dust and Molecules in V4743 Sgr

abstract:
  We present 1.2 mm continuum images and spectral line observations of CO(1--0)
and SiO(3--2) rotational transitions of the recent nova V4743 Sgr. The nova is
detected at 1.2 mm showing a variable millimetre emission. Only upper limits of
T_A* = 0.06 K for CO and T_A* = 0.03 K for SiO could be derived. We discuss the
results in terms the nature of the millimetre emission favouring dust from a
phase before the recent outburst as the likely radiating source. We also
comment on the possibility of free-free emission from the ionised shell as the
source of the measured millimetre radiation.


title: Comparing filters for the detection of point sources

abstract:
  This paper considers filters (the Mexican hat wavelet, the matched and the
scale-adaptive filters) that optimize the detection/separation of point sources
on a background. We make a one-dimensional treatment, we assume that the
sources have a Gaussian profile, i. e. $\tau (x) = e^{- x^2/2R^2}$, and a
background modelled by an homogeneous and isotropic Gaussian random field,
characterised by a power spectrum $P(q)\propto q^{-\gamma}, \gamma \geq 0$.
Local peak detection is used after filtering. Then, the Neyman-Pearson
criterion is used to define the confidence level for detections and a
comparison of filters is done based on the number of spurious and true
detections. We have performed numerical simulations to test theoretical ideas
and conclude that the results of the simulations agree with the analytical
results.


title:
Obscured Asymptotic Giant Branch Variables in the Large Magellanic Cloud
  and the Period-Luminosity Relation

abstract:
  The characteristics of oxygen-rich and carbon-rich, large amplitude (dK>0.4
mag), asymptotic giant branch variables in the Large Magellanic Clouds are
discussed, with an emphasis on those obscured by dust. Near-infrared
photometry, obtained over about 8 years, is combined with published
mid-infrared observations from IRAS and ISO to determine bolometric magnitudes
for 42 stars. Pulsation periods of the O-rich stars are in the range 116<P<1393
days, while those for C-rich stars have 298<P<939 days. In addition to the
regular pulsations, one O-rich star and four C-rich stars show large amplitude,
dK> 0.6 mag, secular or very long period variations which may be associated
with changes in their mass-loss rates. We discuss and compare various methods
of determining the bolometric magnitudes and show, perhaps surprisingly, that
most of the very long period stars seem to follow an extrapolation of the
period-luminosity relation determined for stars with shorter periods - although
the details do depend on how the bolometric magnitudes are calculated. Three
stars with thin shells, which are clearly more luminous than the obscured AGB
stars, are undergoing hot bottom burning, while other stars with similar
luminosities have yet to be investigated in sufficient detail to determine
their status in this regard. We suggest that an apparent change in slope of the
period luminosity relation around 400-420 days is caused by variables with
luminosities brighter than the predictions of the core-mass luminosity
relation, due to excess flux from hot bottom burning.


title: Near-infrared constraints on the driving mechanisms for spiral structure

abstract:
  We have imaged a sample of 17 inclined spiral galaxies with measured
H$\alpha$ rotation curves in the K-band, in order to determine the morphology
of the old stellar population which dominates the mass in the disc. The K-band
images of the galaxies have been used to determine the radial extent of
Grand-Design spiral structure and compare this with the turnover radius in
their rotation curves, where the rotation curve transforms from solid-body
rotation to differential rotation. Thus, if the arms do not extend past this
radius, the winding problem is solved. We find in all 17 cases, the arms extend
past this radius, with the radius of grand-design spiral structure being a
factor of 1.3-9.6 times larger than the rotation curve turnover radius. Of
these galaxies, 4 have nearby neighbours and central bars and a further 7 have
a central bar. These bars or near neighbours may be the cause of the driving of
the spiral potential in the discs of these galaxies. Of the remaining 6
galaxies, 5 show some evidence for a bar or oval distortion in their K-band
images. The remaining galaxy (UGC 14) shows no evidence for a central bar and
has no nearby neighbours.
  Finally we also find that the spiral structure of these galaxies in the
near-infrared is extremely regular, although some range in the regularity of
spiral structure is found. To quantify this range in spiral structure, we
introduce the dust-penetrated arm class, which is analogous to the
dust-penetrated classification scheme of Block & Puerari (1999) and based on
the optical arm class of Elmegreen & Elmegreen (1982).


title:
A Survey for H2O Megamasers III. Monitoring Water Vapor Masers in Active
  Galaxies

abstract:
  We present single-dish monitoring of the spectra of 13 extragalactic water
megamasers taken over a period of 9 years and a single epoch of sensitive
spectra for 7 others. Our data include the first K-band science observations
taken with the new 100 m Green Bank Telescope (GBT). In the context of a
circumnuclear, molecular disk model, our results suggest that either (a) the
maser lines seen are systemic features subject to a much smaller acceleration
than present in NGC 4258, presumably because the gas is farther from the
nuclear black hole, or (b) we are detecting ``satellite'' lines for which the
acceleration is in the plane of the sky.
  We also report a search for water vapor masers towards the nuclei of 58
highly inclined, nearby galaxies.


title:
Is the Redshift Clustering of Long-Duration Gamma-Ray Bursts
  Significant?

abstract:
  The 26 long-duration gamma-ray bursts (GRBs) with known redshifts form a
distinct cosmological set, selected differently than other cosmological probes
such as quasars and galaxies. Since the progenitors are now believed to be
connected with active star-formation and since burst emission penetrates dust,
one hope is that with a uniformly-selected sample, the large-scale redshift
distribution of GRBs can help constrain the star-formation history of the
Universe. However, we show that strong observational biases in ground-based
redshift discovery hamper a clean determination of the large-scale GRB rate and
hence the connection of GRBs to the star formation history. We then focus on
the properties of the small-scale (clustering) distribution of GRB redshifts.
When corrected for heliocentric motion relative to the local Hubble flow, the
observed redshifts appear to show a propensity for clustering: 8 of 26 GRBs
occurred within a recession velocity difference of 1000 km/s of another GRB.
That is, 4 pairs of GRBs occurred within 30 h_65^-1 Myr in cosmic time, despite
being causally separated on the sky. We investigate the significance of this
clustering. Comparison of the numbers of close redshift pairs expected from the
simulation with that observed shows no significant small-scale clustering
excess in the present sample; however, the four close pairs occur only in about
twenty percent of the simulated datasets (the precise significance of the
clustering is dependent upon the modeled biases). We conclude with some
impetuses and suggestions for future precise GRB redshift measurements.


title: Gas Dynamics in Central Parts of Galaxies

abstract:
  Asymmetries in galactic potentials, either self-induced, or caused by a
passing companion, play an important role in global gas dynamics in galaxies.
In particular, they are able to trigger gas inflow, which in turn feeds nuclear
activity. In the inner kiloparsec, the inflowing gas becomes subject to various
resonances induced by asymmetry in the potential. This produces complicated gas
morphology and dynamics seen in the nuclear rings and spirals. Formation of
nuclear rings is related to barred galaxies, and explained by the orbital
structure in bars. One can get basic understanding of weak nuclear spirals from
the linear wave theory, but stronger spirals are likely to be out of the linear
regime, and they appear as spiral shocks in hydrodynamical models. In addition,
nuclear stellar bars are observed in a considerable fraction of disc galaxies,
often nested inside the large bar; their orbital structure further modifies the
nuclear gas dynamics. If a massive black hole (MBH) is present in the galactic
centre, it governs the resonances even beyond its classically defined sphere of
influence. Since resonances shape gas dynamics in the nuclear region, the
central black hole should be able to regulate gas flow around itself.


title:
FUSE Detection of Galactic OVI Emission in the Halo above the Perseus
  Arm

abstract:
  Background observations obtained with the Far Ultraviolet Spectroscopic
Explorer (FUSE) toward l=95.4, b=36.1 show OVI 1032,1038 in emission. This
sight line probes a region of stronger-than-average soft X-ray emission in the
direction of high-velocity cloud Complex C above a part of the disk where
Halpha filaments rise into the halo. The OVI intensities, 1600+/-300
ph/s/cm^2/sr (1032A) and 800+/-300 ph/s/cm^2/sr (1038A), are the lowest
detected in emission in the Milky Way to date. A second sight line nearby
(l=99.3, b=43.3) also shows OVI 1032 emission, but with too low a
signal-to-noise ratio to obtain reliable measurements. The measured
intensities, velocities, and FWHMs of the OVI doublet and the CII* line at
1037A are consistent with a model in which the observed emission is produced in
the Galactic halo by hot gas ejected by supernovae in the Perseus arm. An
association of the observed gas with Complex C appears unlikely.


title: Bump Cepheids and the Stellar Mass-Luminosity Relation

abstract:
  We present the results of non-linear pulsation modeling of bump Cepheids in
the LMC and SMC. By obtaining an optimal fit to the observed MACHO V and R
lightcurves we can determine the fundamental parameters of each Cepheid, namely
mass, luminosity, effective temperature, distance modulus and reddening. We are
able to describe the mass-luminosity relation for core-He burning intermediate
mass stars. The mass-luminosity relation depends critically upon the level of
internal mixing during the course of the star's main-sequence evolution. Under
the paradigm of convective core overshoot, our results enable us to place tight
quantitative limits of the level of overshoot. We derive an overshooting
parameter of \Lambda_c of 0.65+-0.03 and 0.67+-0.04l/H_p for the LMC and SMC
respectively.


title: New neighbours: V. 35 DENIS late-M dwarfs between 10 and 30 parsecs

abstract:
  This paper reports updated results on our systematic mining of the DENIS
database for nearby very cool M-dwarfs (M6V-M8V, 2.0<I-J<3.0, photometric
distance within 30 pc), We calibrate the DENIS (M_I, I-J) colour-luminosity
relationship from M dwarfs with well measured parallaxes (HIP, GCTP,...),
obtaining distance errors for single dwarfs of 25%. Using proper motions
measured on archive Schmidt plates for stars that meet the photometric
selection criteria, we eliminate the giants by a Reduced Proper Motion cutoff,
which is significantly more selective than a simple proper motion cutoff.
  Here we present new data for 62 red dwarf candidates selected over 5700
square degrees in the DENIS database. 26 of those originate in the 2100 square
degrees analysed in Paper I, with improved parameters here, and 36 were found
in 3600 additional square degrees. 25 of those are new nearby dwarfs. We
determine from that sample of 62 stars a stellar density for 12.0<M_I<14.0 of
2.2(+-0.4)E-3 stars/pc^3/mag. This value is consistent with photometric
luminosity functions measured from deeper and smaller-field observations, but
not with the nearby star luminosity function. In addition we cross-identified
the NLTT and DENIS catalogues to find 15 similar stars, in parts of the sky not
yet covered by the colour-selected search.


title: Why Study Interstellar Matter Very Close to the Sun?

abstract:
  Interstellar matter (ISM) sets the boundary conditions of the heliosphere and
dominates the interplanetary medium. The heliosphere configuration has varied
over recent history, as the Sun emerged from the Local Bubble and entered a
turbulent outflow of cloudlets originating from the Scorpius-Centaurus
Association direction. Several indicators suggest that the local interstellar
magnetic field is weak and parallel to the galactic plane. Observations of the
interaction products of the ISM with the heliosphere, such as pickup ions and
anomalous cosmic rays, when combined with data on the ISM towards nearby stars,
provide unique constraints on the composition and physical properties of nearby
gas. These data suggest abundances in nearby ISM are subsolar, and that gas and
dust are not well mixed at the solar location.


title: Stellar Masses of Luminous Compact Blue Galaxies at Redshifts z=0.4-1.2

abstract:
  We present stellar mass measurements for a sample of 36 Luminous Compact Blue
Galaxies (LCBGs) at redshifts z = 0.4-1.2 in the Flanking Fields around the
Hubble Deep Field North. The technique is based on fitting a two-component
galaxy population model to multi-broadband photometry. Best-fit models are
found to be largely independent on the assumed values for the IMF and the
metallicity of the stellar populations, but are sensitive to the amount of
extinction and the extinction law adopted. On average, the best-fit model
corresponds to a LMC extinction law with E(B-V)=0.5. Stellar mass estimates,
however, are remarkably independent on the final model choice. Using a Salpeter
IMF, the derived median stellar mass for this sample is 5 x 10^9 Mo, i.e., ~2
times smaller than previous virial mass estimates. Despite uncertainties of a
factor 2-3, our results strengthen prior claims that L* CBGs at intermediate
redshifts are, on average, about 10 times less massive than a typical L* galaxy
today.


title: Free-Free Absorption and the Unified Scheme

abstract:
  We report Very-Long-Baseline Array (VLBA) observations at 2.3, 8.4, and 15.4
GHz towards nine GHz-Peaked Spectrum (GPS) sources. One Seyfert 1 galaxy, one
Seyfert 2 galaxy, three radio galaxies, and four quasars were included in our
survey. We obtained spatial distributions of the Free-Free Absorption (FFA)
opacity with milliarcsec resolutions for all sources. It is found that type-1
(Seyfert 1 and quasars) and type-2 (Seyfert 2 and radio galaxies) sources
showed different distributions of the FFA opacities. The type-1 sources tend to
show more asymmetric opacity distributions towards a double lobe, while those
of the type-2 sources are rather symmetric. Our results imply that the
different viewing angle of the jet causes the difference of FFA opacity along
the external absorber. This idea supports the unified scheme between quasars
and radio galaxies, proposed by Barthel (1989).


title:
Velocity Dispersion in the Halo of omega Centauri: No need for MOND
  given the present data

abstract:
  Scarpa et al. (2003) have used their new measurements of the line-of-sight
velocity dispersion at radii R ~ 30-45 pc in omega Centauri to argue for
modifications to Newtonian dynamics (MOND) at low accelerations in the outer
reaches of this globular cluster. Alternatively, any such evidence could be
taken as an indication of the presence of an extended dark-matter halo. We show
that the data of Scarpa et al. are in fact consistent with earlier observations
by Seitzer and by Meylan et al., which are in turn well described at large
radii by simple, self-consistent dynamical models. There is no need to invoke
MOND or dark matter to explain the current data.


title:
On hydrodynamic shear turbulence in Keplerian disks: via transient
  growth to bypass transition

abstract:
  This paper deals with the problem of hydrodynamic shear turbulence in
non-magnetized Keplerian disks. We wish to draw attention to a route to
hydrodynamic turbulence which seems to be little known by the astrophysical
community, but which has been intensively discussed among fluid dynamicists
during the past decade. In this so-called `bypass' concept for the onset of
turbulence, perturbations undergo a transient growth, and they may reach an
amplitude that is sufficiently large to allow positive feedback through
nonlinear interactions. This transient growth is linear in nature, and thus it
differs in principle from the well-known nonlinear instability. We describe the
type of perturbations that according to this process are the most likely to
lead to turbulence, namely non-axisymmetric vortex mode perturbations in the
two dimensional limit. We show that the apparently inhibiting action of the
Coriolis force on the dynamics of such vortical perturbations is substantially
diminished due to the pressure perturbations, contrary to current opinion. We
stress the similarity of the turbulent processes in Keplerian disks and in
Cartesian flows and conclude that the prevalent skepticism of the astrophysical
community on the occurrence of hydrodynamic shear turbulence in such disks is
not founded.


title: Chemical Composition of the Early Universe

abstract:
  A prediction of standard inflationary cosmology is that the elemental
composition of the medium out of which the earliest stars and galaxies
condensed consisted primarily of hydrogen and helium 4He with small admixtures
of deuterium, lithium 7Li, and 3He. The most red-shifted quasars, galaxies, and
Ly-alpha absorbers currently observed, however, all exhibit at least some
admixture of heavier elements, as do the most ancient stars in the Galaxy. Here
we examine ways in which the abundance of these same elements, if present
before the epoch of population III formation, might be observationally
established or ruled out.


title:
On the Geometry of the High-Velocity Ejecta of the Peculiar Type Ia
  Supernova 2000cx

abstract:
  High-velocity features in Type Ia supernova spectra provide a way to probe
the outer layers of these explosions. The maximum-light spectra of the unique
Type Ia supernova 2000cx exhibit interesting Ca II features with high-velocity
components. The infrared triplet absorption is quadruply notched, while the H&K
absorption is wide and flat. Stimulated by a three-dimensional interpretation
of similar Ca II features in another Type Ia supernova (SN 2001el, Kasen et al.
2003), we present alternative spherically symmetric and three-dimensional
ejecta models to fit the high-velocity (v > 16,000 km/s) Ca II features of SN
2000cx. We also present simple estimates of the high-velocity ejecta mass for a
few trial compositions and discuss their implications for explosion modelling.


title: The r-process in supernova explosions from the collapse of O-Ne-Mg cores

abstract:
  We examine r-process nucleosynthesis in a "prompt supernova explosion" from
an 8-10 Msun progenitor star, as an alternative scenario to the "neutrino wind"
mechanism. In the present model, the progenitor star has formed an
oxygen-neon-magnesium core at its center. The core-collapse simulations are
performed with a one-dimension, Newtonian hydrodynamic code. We obtain a very
weak prompt explosion, in which no r-processing occurs. We further simulate
energetic prompt explosions by enhancement of the shock-heating energy, in
order to investigate conditions necessary for the production of r-process
nuclei in such events. The highly neutronized ejecta (Ye = 0.14-0.20) leads to
robust production of r-process nuclei; their relative abundances are in
excellent agreement with the solar r-process pattern. Our results suggest that
prompt explosions of 8-10 Msun stars with oxygen-neon-magnesium cores can be a
promising site of r-process nuclei.


title:
Adaptive spatial binning of integral-field spectroscopic data using
  Voronoi tessellations

abstract:
  We present new techniques to perform adaptive spatial binning of
Integral-Field Spectroscopic (IFS) data to reach a chosen constant
signal-to-noise ratio per bin. These methods are required for the proper
analysis of IFS observations, but can also be used for standard photometric
imagery or any other two-dimensional data. Various schemes are tested and
compared by binning and extracting the stellar kinematics of the Sa galaxy
NGC2273 from spectra obtained with the panoramic IFS SAURON.


title:
Probing the star formation epoch with Wilkinson Microwave Anisotropy
  Probe (WMAP) data and high-redshift QSOs

abstract:
  Using the values of the cosmological parameters obtained from Wilkinson
Microwave Anisotropy Probe (WMAP) and the cosmological chemical clock observed
by high-redshift quasars, it is shown that star formation should have started
by the redshift $z_F > 9.5$, and that $z_F$ is sensitive only to $\omegamz h^2$
in flat $\Lambda$CDM cosmology.


title: Quintessence and the Curvature of the Universe after WMAP

abstract:
  We study quintessence models with a constant (effective) equation of state.
It is investigated whether such quintessence models are consistent with a
negative spatial curvature of the Universe with respect to the anisotropy of
the cosmic microwave background radiation measured by the WMAP mission. If the
reionization is negligibly small, it is found that such models with negative
curvature are admissible due to a geometrical degeneracy. However, a very high
optical depth tau to the surface of last scattering, as indicated by the
polarization measurements of WMAP, would rule out such models.


title:
Chandra Observations of Nuclear X-ray Emission from a Sample of Radio
  Sources

abstract:
  We present the X-ray properties of a sample of 17 radio sources observed with
the Chandra X-ray Observatory as part of a project aimed at studying the X-ray
emission from their radio jets. In this paper, we concentrate on the X-ray
properties of the unresolved cores. The sample includes 16 quasars (11
core-dominated and 5 lobe-dominated) in the redshift range z=0.30--1.96, and
one low-power radio-galaxy at z=0.064. No diffuse X-ray emission is present
around the cores of the quasars, except for the nearby low-power galaxy that
has diffuse emission on a scale and with a luminosity consistent with other
FRIs. No high-amplitude, short-term variability is detected within the
relatively short Chandra exposures. However, 1510-089 shows low-amplitude flux
changes with a timescale of $\sim$25 minutes. The X-ray spectra of the quasar
cores are generally well described by a single power law model with Galactic
absorption. However, in six quasars we find soft X-ray excess emission below
1.6 keV. Interestingly, we detect an Fe K-shell emission line, consistent with
fluorescent Kalpha emission from cold Iron, in one lobe- and two core-dominated
sources. The average X-ray photon index for the quasars in the sample is
Gamma=1.66 and dispersion, sigma=0.23. The average spectral slope for our
sample is flatter than the slope found for radio-quiet quasars and for
radio-loud AGNs with larger jet orientations; this indicates that beaming
affects the X-ray emission from the cores in our sample of quasars.


title: Stream eclipse mapping with 'fire-flies'

abstract:
  We apply a new method of eclipse mapping to the light curves of eclipsing
polars. The technique aims to locate the bright emission associated with the
accretion stream, using a technique that makes the fewest prior assumptions
about the location of the accretion stream material. We have obtained data of
EP Dra and HU Aqr with the S-Cam 2 superconducting tunnel junction camera using
the William Herschel Telescope. The location of emission regions in both
systems show that previously assumed trajectories are consistent with those
found using our technique. Most of the emission is located in a region where we
expect material to be confined to magnetic field lines, particularly for HU
Aqr, while there appears to be less emission from where we conventionally
expect material to follow a ballistic trajectory from the L1-point.


title: Groups and the Entropy Floor- XMM-Newton Observations of Two Groups

abstract:
  Using XMM-Newton spatially resolved X-ray imaging spectroscopy we obtain the
temperature, density, entropy, gas mass, and total mass profiles for two groups
of galaxies out to ~0.3 Rvir (Rvir, the virial radius). Our density profiles
agree well with those derived previously, and the temperature data are broadly
consistent with previous results but are considerably more precise. Both of
these groups are at the mass scale of 2x10^13 Msolar but have rather different
properties. They have considerably lower gas mass fractions at r<0.3 Rvir than
the rich clusters. NGC2563, one of the least luminous groups for its X-ray
temperature, has a very low gas mass fraction of ~0.004 inside 0.1 Rvir, which
rises with radius. NGC4325, one of the most luminous groups at the same average
temperature, has a higher gas mass fraction of 0.02. The entropy profiles and
the absolute values of the entropy as a function of virial radius also differ,
with NGC4325 having a value of ~100 keV cm-2 and NGC2563 a value of ~300 keV
cm-2 at r~0.1 Rvir. For both groups the profiles rise monotonically with radius
and there is no sign of an entropy "floor". These results are inconsistent with
pre-heating scenarios which have been developed to explain the entropy floor in
groups but are broadly consistent with models of structure formation which
include the effects of heating and/or the cooling of the gas. The total entropy
in these systems provides a strong constraint on all models of galaxy and group
formation, and on the poorly defined feedback process which controls the
transformation of gas into stars and thus the formation of structure in the
universe.


title:
The SZ effect contribution to WMAP. A Cross-Correlation between WMAP and
  ROSAT

abstract:
  We cross-correlate WMAP and ROSAT diffuse X-ray background maps and look for
common features in both data sets. We use the power spectrum of the product
maps and the cross-power spectrum to highlight a possible correlation. The
power spectrum of the product maps does not detect any correlation and the
cross-power spectrum does not show any significant deviation from 0. We explore
different explanations for this lack of correlation. A universe with a low
value of Sigma_8 could naturally explain the lack of correlation. We also
discuss the systematic effects which can affect this result, in particular the
subtraction of some cluster signal from the ROSAT diffuse maps which could
significantly suppress the correlation signal. These systematic effects reduce
considerably the significance of our constraints on the cosmological model.
When we include the systematic effects we find a weaker constrain on Sigma_8
allowing models with values as large as Sigma_8=1 (for Omega_m = 0.3) to be
consistent with the lack of correlation. To illustrate the capabilities of the
method with future high-quality data, we show how from the correlation signal
it should be possible to predict the level of contamination of the SZ effect on
the power spectrum of the CMB. Within the systematic errors we find evidence
that this contribution is negligible for WMAP and is expected to be small in
experiments like ACBAR or CBI, but can be important for future high resolution
experiments.


title:
Constraints on distances to Galactic Centre non-thermal filaments from
  HI absorption

abstract:
  We have studied HI absorption towards three non-thermal filaments (NTFs)
Sgr-C, G359.54+0.18 and G359.79+0.17 using the Giant Metrewave Radio Telescope
(GMRT). Our study, for the first time, constrains the distance of the Sgr C NTF
and the HII region seen associated with the NTF in the sky plane, to within a
few hundred parsecs from the Galactic Centre (GC). A molecular cloud with a
velocity of -100 km/s appears to be associated with the central part of the Sgr
C NTF. Our study also indicates that the Sgr C HII region is relatively farther
away than the NTF along our line of sight, and thereby provides evidence
against any possible interaction between the two objects. The NTF G359.54+0.18
shows weak HI absorption (4 sigma detection) at a velocity of -140 km/s, which
is the velocity of a known dense molecular cloud seen towards the NTF. This
cloud is expected to be located within ~200 pc from the GC and thereby provides
a lower limit to the distance. The upper limit to the distance of this NTF from
the Sun is 10.5 kpc. The distance to the NTF G359.79+0.17 is between 5.1 and
10.5 kpc from the Sun.


title: Flaring X-ray Emission from HST-1, a Knot in the M87 Jet

abstract:
  We present Chandra X-ray monitoring of the M87 jet in 2002, which shows that
the intensity of HST-1, an optical knot 0.8" from the core, increased by a
factor of two in 116 days and a factor of four in 2 yrs. There was also a
significant flux decrease over two months, with suggestive evidence for a
softening of the spectrum. From this variability behavior, we argue that the
bulk of the X-ray emission of HST-1 comes from synchrotron emission. None of
the other conceivable emission processes can match the range of observed
characteristics. By estimating synchrotron model parameters for various bulk
relativistic velocities, we demonstrate that a model with a Doppler factor,
delta, in the range 2 to 5 fits our preliminary estimates of light travel time
and synchrotron loss timescales.


title:
The variability of accretion onto Schwarzschild black holes from
  turbulent magnetized discs

abstract:
  We use global magnetohydrodynamic simulations, in a pseudo-Newtonian
potential, to investigate the temporal variability of accretion discs around
Schwarzschild black holes. We use the vertically-averaged magnetic stress in
the simulated disc as a proxy for the rest-frame dissipation, and compute the
observed emission by folding this through the transfer function describing the
relativistic beaming, light bending and time delays near a non-rotating black
hole. The temporal power spectrum of the predicted emission from individual
annuli in the disc is described by a broken power law, with indices of -3.5 at
high frequency and 0 to -1 at low frequency. Integrated over the disc, the
power spectrum is approximated by a single power law with an index of -2.
Increasing inclination boosts the relative power at frequencies of around 0.3
times the orbital frequency at the marginally stable orbit, but no evidence is
found for sharp quasi-periodic oscillations in the lightcurve. Assuming that
fluorescent iron line emission locally tracks the continuum flux, we compute
simulated broad iron line profiles. We find that relativistic beaming of the
non-axisymmetric emission profile, induced by turbulence, produces
high-amplitude variability in the iron line profile. We show that this
substructure within the broad iron line profile can survive averaging over a
number of orbital periods, and discuss the origin of the anomalous X-ray
spectral features, recently reported by Turner et al. (2002) for the Seyfert
galaxy NGC3516, in the context of turbulent disc models.


title: Mixing and the s-process in rotating AGB stars

abstract:
  We model the nucleosynthesis during a radiative interpulse phase of a
rotating 3Msun Asymptotic Giant Branch (AGB) star. We find an enhanced
production of the neutron source species C13 compared to non-rotating models
due to shear mixing of protons and C12 at the core-envelope interface. We
estimate that the resulting total production of heavy elements by slow neutron
capture s-process is too low to account for most observations. This due to the
fact that rotationally induced mixing during the interpulse phase causes a
pollution of the C13 pocket layer with the neutron poison N14. As a result we
find a maximum neutron exposure of tau_max=0.04mbarn^{-1} in the s-process
layer of our solar metallicity model with rotation. This is about a factor of 5
to 10 less than required to reproduce the observed stellar s-process abundance
patterns. We compare our results with models that include hydrodynamic
overshooting mixing, and with simple parametric models including the combined
effects of overshooting and mixing in the interpulse. Within the parametric
model a range of mixing efficiencies during the interpulse phase correlates
with a spread in the s-process efficiency. Such a spread is observed in AGB and
post-AGB stars as well as in pre-solar SiC grains.


title: Investigation of the polarizable vacuum cosmology

abstract:
  The basic cosmological predictions of a `polarizable-vacuum' theory of
gravity due to Dicke, predating the scalar-tensor theory, are investigated and
tested for their compliance with current observations. A Friedmann-like
equation is derived for the theory that differs in a significant way from that
of GR, for which it is demonstrated that a big bang is not a solution: the
initial scale factor may be small but not zero, and must have zero first
derivative. Detailed graphs of the predictions of the theory for combinations
of the density parameters are given. It is shown that these predictions are
compatible with current estimates for the age and deceleration parameter, and
the maximum observable redshift, provided the matter density $\Omega_m$ is
close to the luminous matter density, i.e. provided there is not a significant
amount of missing mass. For these best fit parameters, the theory predicts a
maximum initial temperature that is too small for BBN and probably too small to
support an era of radiation domination. The theory predicts a radiation power
from a binary system that is 2/3 that predicted by GR, and so incompatible with
observed orbital decay rate of PSR 1913 + 16. There is some discussion of
possible developments, including reconciliation through accommodation of vacuum
anisotropy, and of the relation between PV and the Yilmaz theory and the
quasi-steady-state cosmology.


title: Dynamical Modeling of SAURON Galaxies

abstract:
  We describe our program for the dynamical modeling of early-type galaxies
observed with the panoramic integral-field spectrograph SAURON. We are using
Schwarzschild's numerical orbit superposition method to reproduce in detail all
kinematical and photometric observables, and recover the intrinsic orbital
structure of the galaxies. Since catastrophes are the most prominent features
in the orbital observables, two-dimensional kinematical coverage is essential
to constrain the dynamical models.


title: X-ray emission from expanding cocoons

abstract:
  X-ray observations of extragalactic radiosources show strong evidences of
interaction between the radio emitting plasma and the X-ray emitting ambient
gas. In this paper we perform a detailed study of this interaction by numerical
simulations. We study the propagation of an axisymmetric supersonic jet in an
isothermal King atmosphere and we analyze the evolution of the resulting X-ray
properties and their dependence on the jet physical parameters. We show the
existence of two distinct and observationally different regimes of interaction,
with strong and weak shocks. In the first case shells of enhanced X-ray
emission are to be expected, while in the second case we expect deficit of
X-ray emission coincident with the cocoon. By a comparison between analytical
models and the results of our numerical simulations, we discuss the dependence
of the transition between these two regimes on the jet parameters and we find
that the mean controlling quantity results to be the jet kinetic power. We then
discuss how the observed jets can be used to constrain the jet properties.