title:
A New Search Paradigm for Correlated Neutrino Emission from Discrete
  GRBs using Antarctic Cherenkov Telescopes in the Swift Era

abstract:
  We describe the theoretical modeling and analysis techniques associated with
a preliminary search for correlated neutrino emission from GRB980703a, which
triggered the Burst and Transient Source Experiment (BATSE GRB trigger 6891),
using archived data from the Antarctic Muon and Neutrino Detector Array
(AMANDA-B10). Under the assumption of associated hadronic acceleration, the
expected observed neutrino energy flux is directly derived, based upon
confronting the fireball phenomenology with the discrete set of observed
electromagnetic parameters of GRB980703a, gleaned from ground-based and
satellite observations, for four models, corrected for oscillations. Models 1
and 2, based upon spectral analysis featuring a prompt photon energy fit to the
Band function, utilize an observed spectroscopic redshift, for isotropic and
anisotropic emission geometry, respectively. Model 3 is based upon averaged
burst parameters, assuming isotropic emission. Model 4, based upon a Band fit,
features an estimated redshift from the lag-luminosity relation with isotropic
emission. Consistent with our AMANDA-II analysis of GRB030329, which resulted
in a flux upper limit of ~0.150 GeV/cm^2/s for model 1, we find differences in
excess of an order of magnitude in the response of AMANDA-B10, among the
various models for GRB980703a. Implications for future searches in the era of
Swift and IceCube are discussed.


title: Strongly induced collapse in the Class 0 protostar NGC 1333 IRAS 4A

abstract:
  The onset of gravitational collapse in cluster-forming clouds is still poorly
known. Our goal is to use the Class 0 protostar IRAS 4A, which is undergoing
collapse in the active molecular cloud NGC 1333, to set constraints on this
process. In particular we want to measure the mass infall rate and investigate
whether the collapse could have been triggered by a strong external
perturbation. We analyze existing continuum observations to derive the density
structure of the envelope, and use our new molecular line observations done
with the IRAM 30m telescope to probe its velocity structure. We perform a
detailed comparison of this set of data with a numerical model of collapse
triggered by a fast external compression. Both the density and velocity
structures of the envelope can be well fitted by this model of collapse induced
by a fast external compression for a time elapsed since point mass formation of
1-2 x 10**4 yr. We deduce a large mass infall rate of 0.7-2 x 10**-4 Msun/yr.
The momentum required for the perturbation to produce this large mass infall
rate is of the same order as the momenta measured for the NGC 1333 numerous
outflows. Our analysis shows also that the turbulence is highly non uniform in
the envelope, dropping from supersonic to subsonic values toward the center.
The inner subsonic turbulence is most likely a relic of the conditions
prevailing in the dense core before the onset of collapse. The vigorous
collapse undergone by IRAS 4A was triggered by a fast external compression,
probably related to the expansion of a nearby cavity, which could have
triggered the collapse of the nearby Class 0 protostar IRAS 4B simultaneously.
This cavity could have been generated by an outflow but we have not found a
good protostellar candidate yet.


title:
AGB stars in the Magellanic Clouds. III. The rate of star formation
  across the SMC

abstract:
  This article compares the Ks magnitude distribution of Small Magellanic Cloud
asymptotic giant branch stars obtained from the DENIS and 2MASS data with
theoretical distributions. Theoretical Ks magnitude distributions have been
constructed using up-to-date stellar evolution calculations for low and
intermediate-mass stars, and in particular for thermally pulsing asymptotic
giant branch stars. Separate fits of the magnitude distributions of carbon- and
oxygen-rich stars allowed us to constrain the metallicity distribution across
the galaxy and its star formation rate. The Small Magellanic Cloud stellar
population is found to be on average 7-9 Gyr old but older stars are present at
its periphery and younger stars are present in the direction of the companion
galaxy the Large Magellanic Cloud. The metallicity distribution traces a
ring-like structure that is more metal rich than the inner region of the
galaxy. The C/M ratio discussed in Paper I is a tracer of the metallicity
distribution only if the underlying stellar population is of intermediate-age.


title:
OB Stars in the Solar Neighborhood I: Analysis of their Spatial
  Distribution

abstract:
  We present a newly-developed, three-dimensional spatial classification
method, designed to analyze the spatial distribution of early type stars within
the 1 kpc sphere around the Sun. We propose a distribution model formed by two
intersecting disks -the Gould Belt (GB) and the Local Galactic Disk (LGD)-
defined by their fundamental geometric parameters. Then, using a sample of
about 550 stars of spectral types earlier than B6 and luminosity classes
between III and V, with precise photometric distances of less than 1 kpc, we
estimate for some spectral groups the parameters of our model, as well as
single membership probabilities of GB and LGD stars, thus drawing a picture of
the spatial distribution of young stars in the vicinity of the Sun.


title:
On the incidence rate of first overtone Blazhko stars in the Large
  Magellanic Cloud

abstract:
  By using the full span of multicolor data on a representative sample of first
overtone RR Lyrae stars in the Large Magellanic Cloud (LMC) we revisit the
problem of the incidence rate of the amplitude/phase-modulated (Blazhko) stars.
Multicolor data, obtained by the MAssive Compact Halo Objects (MACHO) project,
are utilized through a periodogram averaging method. This enables us to
increase the number of detected multiperiodic variables by 18% relative to the
number obtained by the analysis of the best single color data. We also test the
maximum modulation period detectable in the present dataset. We find that
variables showing amplitude/phase modulations with periods close to the total
time span can still be clearly separated from the class of stars showing period
changes. This larger limit on the modulation period, the more efficient data
analysis and the longer time span lead to a substantial increase in the
incidence rate of the Blazhko stars in comparison with earlier results. We find
altogether 99 first overtone Blazhko stars in the full sample of 1332 stars,
implying an incidence rate of 7.5%. Although this rate is nearly twice of the
one derived earlier, it is still significantly lower than that of the
fundamental mode stars in the LMC. The by-products of the analysis (e.g.,
star-by-star comments, distribution functions of various quantities) are also
presented.


title: An X-ray bright ERO hosting a type 2 QSO

abstract:
  We present the XMM-Newton and the optical-VLT spectra along with the optical
and the near-infrared photometric data of one of the brightest X-ray (F(2-10
keV)~1e-13 erg/s cm^2) extremely red objects (R-K>=5) discovered so far. The
source, XBSJ0216-0435, belongs to the XMM-Newton Bright Serendipitous Survey
and it has extreme X-ray-to-optical (~220) and X-ray-to-near-infrared (~60)
flux ratios. Thanks to its brightness, the X-ray statistics are good enough for
an accurate spectral analysis by which the presence of an X-ray obscured
(NH>1e22 cm^-2) QSO (L(2-10 keV)=4e45 erg/s) is determined. A statistically
significant (~99%) excess around 2 keV in the observed-frame suggests the
presence of an emission line. By assuming that this feature corresponds to the
iron Kalpha line at 6.4 keV, a first estimate of the redshift of the source is
derived (z_x~2). The presence of a high redshift QSO2 has been finally
confirmed through dedicated VLT optical spectroscopic observations
(z_o=1.985+/-0.002). This result yields to an optical validation of a new X-ray
Line Emitting Object (XLEO) for which the redshift has been firstly derived
from the X-ray data. XBSJ0216-0435 can be considered one of the few examples of
X-ray obscured QSO2 at high redshift for which a detailed X-ray and optical
spectral analysis has been possible. The spectral energy distribution from
radio to X-rays is also presented. Finally from the near-infrared data the
luminosity and the stellar mass of the host galaxy has been estimated finding a
new example of the coexistence at high-z between massive galaxies and powerful
QSOs.


title: Multiwavelength analysis of the young open cluster NGC 2362

abstract:
  We present a multiwavelength analysis of the young open cluster NGC 2362.
UBVRcIc CCD photometric observations, together with available data in the
Chandra data base, near infrared data from the Two Micron All Sky Survey
(2MASS), and recently published Halpha spectroscopy were used to get
information about the evolutionary stage of the cluster and the main physical
properties of its stellar content. Cluster membership is estimated for every
individual star by means of ZAMS and isochrone fitting. The cluster is
confirmed to host a richly populated pre-main sequence (PMS), and to contain a
large amount of X-ray emitting stars, which reach from the PMS members of GK
spectral type, up to the most luminous OB type main sequence (MS) members. The
PMS cluster members show no significant age spread, and the comparison to both
PMS and post-MS isochrones suggests a younger age for the more massive MS than
for lower mass PMS members. The analysis allows to asses the validity of
currently used pre-main sequence evolutionary models, and supports the
suggestion of a well defined positive correlation of the X-ray emission from
PMS stars with their bolometric luminosity. Clear differences are found on the
other hand, between the X-ray activity properties of MS and PMS cluster
members, both in the relation between X-ray luminosity and bolometric
luminosity, and in spectral properties as well.


title: The rp-Process in Neutrino-driven Winds

abstract:
  Recent hydrodynamic simulations of core-collapse supernovae with accurate
neutrino transport suggest that the bulk of the early neutrino-heated ejecta is
proton rich, in which the production of some interesting proton-rich nuclei is
expected. As suggested in recent nucleosynthesis studies, the rapid
proton-capture (rp) process takes place in such proton-rich environments by
bypassing the waiting point nuclei with the beta-lives of a few minutes via the
faster capture of neutrons continuously supplied from the neutrino absorption
by protons. In this study, the nucleosynthesis calculations are performed with
the wide ranges of the neutrino luminosities and the electron fractions (Ye),
using the semi-analytic models of proto-neutron star winds. The masses of
proto-neutron stars are taken to be 1.4 Msolar and 2.0 Msolar, where the latter
is regarded as the test for somewhat high entropy winds (about a factor of
two). For Ye > 0.52, the neutrino-induced rp-process takes place in many wind
trajectories, and the p-nuclei up to A ~ 130 are synthesized with interesting
amounts. However, 92Mo is somewhat underproduced compared to those with similar
mass numbers. For 0.46 < Ye < 0.49, on the other hand, 92Mo is significantly
enhanced by the nuclear flows in the vicinity of the abundant 90Zr that
originates from the alpha-process at higher temperature. The nucleosynthetic
yields are averaged over the ejected masses of winds, and further the Ye
distribution predicted by the recent hydrodynamic simulation of a core-collapse
supernova. Comparison of the mass-Ye-averaged yields to the solar compositions
implies that the neutrino-driven winds can be potentially the origin of light
p-nuclei up to A ~ 110, including 92,94Mo and 96,98Ru that cannot be explained
by other astrophysical sites.


title: Cosmological implications of dwarf spheroidal chemical evolution

abstract:
  The chemical properties of dwarf spheroidals in the local group are shown to
be inconsistent with star formation being truncated after the reionization
epoch (z~8). Enhanced levels of [Ba/Y] in stars in dwarf spheroidals like
Sculptor indicate strong s-process production from low-mass stars whose
lifetimes are comparable with the duration of the pre-reionization epoch. The
chemical evolution of Sculptor is followed using a model with SNeII and SNeIa
feedback and mass- and metallicity-dependent nucleosynthetic yields for
elements from H to Pb. We are unable to reproduce the Ba/Y ratio unless stars
formed over an interval long enough for the low-mass stars to pollute the
interstellar medium with s-elements. This robust result challenges the
suggestion that most of the local group dwarf spheroidals are fossils of
reionization and supports the case for large initial dark matter halos.


title:
GRB 050713A: High Energy Observations of the GRB Prompt and Afterglow
  Emission

abstract:
  Swift discovered GRB 050713A and slewed promptly to begin observing with its
narrow field instruments 72.6 seconds after the burst onset, while the prompt
gamma-ray emission was still detectable in the BAT. Simultaneous emission from
two flares is detected in the BAT and XRT. This burst marks just the second
time that the BAT and XRT have simultaneously detected emission from a burst
and the first time that both instruments have produced a well sampled,
simultaneous dataset covering multiple X-ray flares. The temporal rise and
decay parameters of the flares are consistent with the internal shock
mechanism. In addition to the Swift coverage of GRB 050713A, we report on the
Konus-Wind (K-W) detection of the prompt emission in the energy range 18-1150
keV, an upper limiting GeV measurement of the prompt emission made by the MAGIC
imaging atmospheric Cherenkov telescope and XMM-Newton observations of the
afterglow. Simultaneous observation between Swift XRT and XMM-Newton produce
consistent results, showing a break in the lightcurve at T+~15ks. Together,
these four observatories provide unusually broad spectral coverage of the
prompt emission and detailed X-ray follow-up of the afterglow for two weeks
after the burst trigger. Simultaneous spectral fits of K-W with BAT and BAT
with XRT data indicate that an absorbed broken powerlaw is often a better fit
to GRB flares than a simple absorbed powerlaw. These spectral results together
with the rapid temporal rise and decay of the flares suggest that flares are
produced in internal shocks due to late time central engine activity.


title: What can be learned about dark energy evolution?

abstract:
  We examine constraints obtained from SNIa surveys on a two parameter model of
dark energy in which the equation of state $w (z) = P(z) / \rho (z)$ undergoes
a transition over a period significantly shorter than the Hubble time. We find
that a transition between $w \sim -0.2$ and $w \sim -1$ (the first value being
somewhat arbitrary) is allowed at redshifts as low as 0.1, despite the fact
that data extend beyond $z \sim 1$. Surveys with the precision anticipated for
space experiments should allow only slight improvement on this constraint, as a
transition occurring at a redshift as low as $\sim 0.17$ could still remain
undistinguishable from a standard cosmological constant. The addition of a
prior on the matter density $\Omega_\MAT = 0.3$ only modestly improves the
constraints. Even deep space experiments would still fail to identify a rapid
transition at a redshift above 0.5. These results illustrate that a Hubble
diagram of distant SNIa alone will not reveal the actual nature of dark energy
at a redshift above 0.2 and that only the local dynamics of the quintessence
field can be infered from a SNIa Hubble diagram. Combinations, however, seem to
be very efficient: we found that the combination of present day CMB data and
SNIa already excludes a transition at redshifts below 0.8.


title: The dynamics of eccentric accretion discs in superhump systems

abstract:
  We have applied an eccentric accretion disc theory in simplified form to the
case of an accretion disc in a binary system, where the disc contains the 3:1
Lindblad resonance. This is relevant to the case of superhumps in SU Ursae
Majoris cataclysmic variables and other systems, where it is thought that this
resonance leads to growth of eccentricity and a modulation in the light curve
due to the interaction of a precessing eccentric disc with tidal stresses. A
single differential equation is formulated which describes the propagation,
resonant excitation and viscous damping of eccentricity. The theory is first
worked out in the simple case of a narrow ring and leads to the conclusion that
the eccentricity distribution is locally suppressed by the presence of the
resonance, creating a dip in the eccentricity at the resonant radius.
Application of this theory to the superhump case confirms this conclusion and
produces a more accurate expression for the precession rate of the disc than
has been previously accomplished with simple dynamical estimates.


title:
Spiral structure of the Third Galactic Quadrant and the solution to the
  Canis Major debate

abstract:
  With the discovery of the Sagittarius dwarf spheroidal (Ibata et al. 1994), a
galaxy caught in the process of merging with the Milky Way, the hunt for other
such accretion events has become a very active field of astrophysical research.
The identification of a stellar ring-like structure in Monoceros, spanning more
than 100 degrees (Newberg et al. 2002), and the detection of an overdensity of
stars in the direction of the constellation of Canis Major (CMa, Martin et al.
2004), apparently associated to the ring, has led to the widespread belief that
a second galaxy being cannibalised by the Milky Way had been found. In this
scenario, the overdensity would be the remaining core of the disrupted galaxy
and the ring would be the tidal debris left behind. However, unlike the
Sagittarius dwarf, which is well below the Galactic plane and whose orbit, and
thus tidal tail, is nearly perpendicular to the plane of the Milky Way, the
putative CMa galaxy and ring are nearly co-planar with the Galactic disk. This
severely complicates the interpretation of observations. In this letter, we
show that our new description of the Milky Way leads to a completely different
picture. We argue that the Norma-Cygnus spiral arm defines a distant stellar
ring crossing Monoceros and the overdensity is simply a projection effect of
looking along the nearby local arm. Our perspective sheds new light on a very
poorly known region, the third Galactic quadrant (3GQ), where CMa is located.


title:
Radiative Transfer Modeling of Three-Dimensional Clumpy AGN Tori and its
  Application to NGC 1068

abstract:
  Recent observations of NGC 1068 and other AGN support the idea of a
geometrically and optically thick dust torus surrounding the central
supermassive black hole and accretion disk of AGN. In type 2 AGN, the torus is
seen roughly edge-on, leading to obscuration of the central radiation source
and a silicate absorption feature near 10 micron. While most of the current
torus models distribute the dust smoothly, there is growing evidence that the
dust must be arranged in clouds. We describe a new method for modeling near-
and mid-infrared emission of 3-dimensional clumpy tori using Monte Carlo
simulations. We calculate the radiation fields of individual clouds at various
distances from the AGN and distribute these clouds within the torus region. The
properties of the individual clouds and their distribution within the torus are
determined from a theoretical approach of self-gravitating clouds close to the
shear limit in a gravitational potential. We demonstrate that clumpiness in AGN
tori can overcome the problem of over-pronounced silicate features. Finally, we
present model calculations for the prototypical Seyfert 2 galaxy NGC 1068 and
compare them to recent high-resolution measurements. Our model is able to
reproduce both the SED and the interferometric observations of NGC 1068 in the
near- and mid-infrared.


title:
"Anomalous" Optical GRB Afterglows are Common: Two z~4 Bursts, GRB
  060206 and 060210

abstract:
  We report on two recent z~4 gamma-ray bursts (GRBs), GRB 060206 and GRB
060210, for which we have obtained well-sampled optical light curves. Our data,
combined with early optical data reported in the literature, shows unusual
behavior for both afterglows. In R-band GRB 060206 (z=4.045) experienced a slow
early decay, followed by a rapid increase in brightness by factor ~2.5 about 1
hour after the burst. Its afterglow then faded in a broken power-law fashion,
with a smooth break at t_b=0.6 days, but with additional, less dramatic (~10%)
``bumps and wiggles'', well detected in the densely sampled light curve. The
R-band afterglow of GRB 060210 (z=3.91) is also unusual: the light curves was
more or less flat between 60 and 300 sec after the burst, followed by ~70%
increase at ~600 sec after the burst, after which the light curve declined as a
t^{-1.3} power-law. Despite earlier reports to the contrary, we find that for
GRB 060206 X-rays also more or less follow the optical decay, but with
significant variations on short timescales. However, the X-ray afterglow is
contaminated by a nearby, variable source, which especially at late times
obscures the behavior of the X-ray afterglow. We argue that ``anomalous''
optical afterglows are likely to be the norm, and that the rapid variations
often seen in Swift-XRT data would also be seen in the optical light curves,
given good enough sampling. As a result, some of the often employed procedures,
such as deriving the jet opening angle using a smooth broken power-law fit to
the optical light curves, in many cases might have a poor statistical
significance. We argue that the early increase in brighness for both bursts
might be due to the turn-on of the external shock. Existence of such features
could provide valuable additional information about the burst. (Abridged)


title:
Spectroscopic Confirmation of a Large AGN Population in Clusters of
  Galaxies

abstract:
  We have completed a spectroscopic survey of X-ray point sources in eight
low-redshift clusters of galaxies (0.05<z<0.31) and have identified 40 cluster
members with broad-band (0.3-8 keV) X-ray luminosities between L_X = 8x10^{40}
and 4x10^{43} erg/s. There are between two and ten X-ray sources per cluster.
We use visible-wavelength emission lines, X-ray spectral shapes, and
multiwavelength flux ratios to determine that at least 35 of these galaxies are
Active Galactic Nuclei (AGN). From our spectroscopic survey of other candidate
cluster members we estimate that the AGN fraction f_A is ~5% for cluster
galaxies more luminous than M_R = -20 mag hosting AGN with broad-band X-ray
luminosities above L_X = 10^{41} erg/s, or f_A(M_R<-20;L_X>10^{41}) ~ 5%. We
stress that additional, lower-luminosity AGN are expected to be present in the
M_R < -20 mag cluster members. Our data unambiguously demonstrate that cluster
galaxies host AGN more frequently than previously expected. Only four of these
galaxies have obvious visible-wavelength AGN signatures, even though their
X-ray luminosities are too high for their X-ray emission to be due to
populations of low-mass X-ray binaries or hot, gaseous halos. We attribute the
significant difference in visible and X-ray AGN identification to dilution of
low-luminosity AGN spectral signatures by host galaxy starlight and/or
obscuration of accretion onto the central, supermassive black hole.


title: Panchromatic study of GRB 060124: from precursor to afterglow

abstract:
  We present observations of GRB 060124, the first event for which both the
prompt and the afterglow emission could be observed simultaneously and in their
entirety by the three Swift instruments. Indeed, Swift-BAT triggered on a
precursor ~570s before the main burst peak, and this allowed Swift to repoint
the narrow field instruments to the burst position ~350s before the main burst
occurred. GRB 060124 also triggered Konus-Wind, which observed the prompt
emission in a harder gamma-ray band (up to 2MeV). Thanks to these exceptional
circumstances, the temporal and spectral properties of the prompt emission can
be studied in the optical, X-ray and gamma-ray ranges. While the X-ray emission
(0.2-10keV) clearly tracks the gamma-ray burst, the optical component follows a
different pattern, likely indicating a different origin, possibly the onset of
external shocks. The prompt GRB spectrum shows significant spectral evolution,
with both the peak energy and the spectral index varying. As observed in
several long GRBs, significant lags are measured between the hard- and
low-energy components, showing that this behaviour extends over 3 decades in
energy. The GRB peaks are also much broader at soft energies. This is related
to the temporal evolution of the spectrum, and can be accounted for by assuming
that the electron spectral index softened with time. The burst energy
(E_iso~5x10^{53} erg) and average peak energy (E_p~300keV) make GRB 060124
consistent with the Amati relation. The X-ray afterglow is characterized by a
decay which presents a break at t_b~10^5s.


title: The present and the future of cosmology with Gamma Ray Bursts

abstract:
  Gamma Ray Bursts are among the most powerful astrophysical sources and they
release up to 1.e54 erg, if isotropic, in less than few hundred seconds. Their
detection in the hard X/gamma ray band (at energies >10 keV) and out to very
high redshift (z~6.3) makes them a powerful new cosmological tool (a) to study
the reionization epoch, (b) to unveil the properties of the IGM, (c) to study
the present universe geometry and (d) to investigate the nature and cosmic
evolution of the dark energy. While GRBs will surely help to understand the
first two issues in the future, the present link between GRBs and cosmology has
been made concrete by the recent discovery of a tight correlation between their
rest frame prompt and afterglow emission properties which allowed their use as
standard candles.


title:
A Grid of Relativistic, non-LTE Accretion Disk Models for Spectral
  Fitting of Black Hole Binaries

abstract:
  Self-consistent vertical structure models together with non-LTE radiative
transfer should produce spectra from accretion disks around black holes which
differ from multitemperature blackbodies at levels which may be observed. High
resolution, high signal-to-noise observations warrant spectral modeling which
both accounts for relativistic effects, and treats the physics of radiative
transfer in detail. In Davis et al. (2005) we presented spectral models which
accounted for non-LTE effects, Compton scattering, and the opacities due to
ions of abundant metals. Using a modification of this method, we have tabulated
spectra for black hole masses typical of Galactic binaries. We make them
publicly available for spectral fitting as an Xspec model. These models
represent the most complete realization of standard accretion disk theory to
date. Thus, they are well suited for both testing the theory's applicability to
observed systems and for constraining properties of the black holes, including
their spins.


title:
Magnitude-Redshift Relation for SNe Ia, Time Dilation, and Plasma
  Redshift

abstract:
  We have previously shown that the type Ia supernovae data by Riess et al.
match the prediction of the magnitude-redshift relation in the plasma-redshift
cosmology. In this article, we also show that the recent SNLS data, which have
a slightly narrower distribution as reported by Astier et al. in 2005, match
the predictions of the plasma-redshift cosmology. The standard deviation of the
SNLS-magnitude from the predicted curve is only about 0.14. The data indicate
that there is no cosmic time dilation. The big-bang cosmology therefore appears
false. The plasma redshift, which follows from exact evaluation of photons
interaction with hot sparse electron plasma, leads to a quasi-static, infinite,
and everlasting universe. It does not need big bang, dark energy, or dark
matter for describing the observations. It predicts intrinsic redshifts of
galaxies consistent with what is observed. The Hubble constant that best fits
the SNLS data is about 63 km per sec per Mpc. This corresponds to an average
electron density of about 0.0002 per cubic centimeter in intergalactic space.
This density together with the plasma redshift heating to an average plasma
temperature in intergalactic space of about 3 million K explains the observed
isotropic cosmic microwave background (CMB) and the cosmic X-ray background.


title: Optical Detection of Two Intermediate Mass Binary Pulsar Companions

abstract:
  We report the detection of probable optical counterparts for two Intermediate
Mass Binary Pulsar (IMBP) systems, PSR J1528-3146 and PSR J1757-5322. Recent
radio pulsar surveys have uncovered a handful of these systems with putative
massive white dwarf companions, thought to have an evolutionary history
different from that of the more numerous class of Low Mass Binary Pulsars
(LMBPs) with He white dwarf companions. The study of IMBP companions via
optical observations offers us several new diagnostics: the evolution of main
sequence stars near the white-dwarf-neutron star boundary, the physics of white
dwarfs close to the Chandrasekhar limit, and insights into the recycling
process by which old pulsars are spun up to high rotation frequencies. We were
unsuccessful in our attempt to detect optical counterparts of PSR J1141-6545,
PSR J1157-5112, PSR J1435-6100, and PSR J1454-5846.


title:
Turbulent Elasticity of the Solar Convective Zone and the Taylor Number
  Puzzle

abstract:
  Previous work on the angular momentum balance and meridional circulation of
the solar convective zone (SCZ) generally consists either of semi-analytic
approaches in which a simple turbulence model is adopted, or full direct
numerical simulation (DNS) of the hydrodynamics or magnetohydrodynamics (MHD).
In both instances the inclusion of magnetic fields has been troublesome. Also,
both approaches have had difficulty reproducing the known angular velocity
profile of the SCZ; this is the Taylor Number Puzzle.
  I discuss preliminary work in which I incorporate magnetic fields into a
viscoelastic turbulence model for the SCZ and apply this to the problem of
meridional circulation and angular momentum balance. I suggest that such an
approach may help solve the Taylor Number Puzzle of the SCZ and bring
theoretical predictions for the large-scale motion of the SCZ in line with
observations.


title:
The Extended Starformation History of the First Generation of Stars, and
  the Reionization of Cosmic Hydrogen

abstract:
  Population-III (Pop-III) starformation (SF) is thought to be quenched when
the metallicity of the star-forming gas reaches a critical level. At high z,
when the general intergalactic medium (IGM) was enriched with metals, the
fraction of primordial gas already collapsed in minihalos was significantly
larger than the fraction of primordial gas that had already been involved in
Pop-III SF. We argue that this minihalo gas remained largely in a metal-free
state, until these minihalos merged into large systems and formed stars. As a
result, the era of Pop-III SF was significantly prolonged, leading to an
integrated Pop-III SF an order of magnitude larger than expected for an abrupt
transition redshift. The contribution of Pop-III SF to the reionization of
hydrogen could have been significant until z~10 and may have extended to z~6.
Our modeling allows for gradual enrichment of the IGM, feedback from
photo-ionization and screening of reionization by minihalos. Nevertheless,
extended Pop-III SF can result in complex, multi-peaked reionization histories.
The contribution of Pop-III stars to reionization will be tested by the
three-year WMAP results: (1) if Pop-III stars do not contribute to
reionization, tau_es<0.05-0.06 and a rapid reionization at z~6 is expected; (2)
if the product of star formation efficiency and escape fraction for Pop-III
stars is significantly larger than for Pop-II stars, then a maximum tau_es=0.21
is achievable; (3) in a scenario where the product of star formation efficiency
and escape fraction for Pop-III stars is comparable to that for Pop-II stars,
tau_es=0.09-0.12 would be observed, with reionization histories characterized
by an extended ionization plateau from z=7-12. This result holds regardless of
the redshift where the IGM becomes enriched with metals.


title:
Jet-gas interactions in z~2.5 radio galaxies: evolution of the
  ultraviolet line and continuum emission with radio morphology

abstract:
  We present an investigation into the nature of the jet-gas interactions in a
sample of 10 radio galaxies at 2.3<z<2.9 using deep spectroscopy of the UV line
and continuum emission obtained at Keck II and the Very Large Telescope.
Kinematically perturbed gas, which we have shown to be within the radio
structure in previous publications, is always blueshifted with respect to the
kinematically quiescent gas, is usually spatially extended, and is usually
detected on both sides of the nucleus. In the three objects from this sample
for which we are able to measure line ratios for both the perturbed and
quiescent gases, we suggest that the former has a lower ionization state than
the latter.
  We propose that the perturbed gas is part of a jet-induced outflow, with dust
obscuring the outflowing gas that lies on the far side of the object. The
spatial extent of the blueshifted perturbed gas, typically ~35 kpc, implies
that the dust is spatially extended at least on similar spatial scales.
  We also find interesting interrelationships between UV line, UV continuum and
radio continuum properties of this sample.


title:
HI 21cm observations of the PG1216+069 sub-DLy-alpha absorber field at
  z=0.00632

abstract:
  The Westerbork Synthesis Radio Telescope finds a weak 21cm line emission
feature at the coordinates (RA-Dec-velocity) of the sub-Damped Lyman-alpha
absorber observed at z_abs=0.00632 in the spectrum of PG1216+069. The emission
feature, WSRT-J121921+0639, lies within 30" of the quasar sightline, is
detected at 99.8% (3 sigma) confidence level, has M_HI between 5 and 15x10^6
M_solar, and has velocity spread between 20 and 60 km/s. Other HI emitters in
the field include VCC297 at a projected distance of 86/h_75 kpc and a
previously unreported HI cloud, WSRT-J121919+0624 at 112/h_75 kpc with M_HI ~
3x10^8 M_solar. The optically identified, foreground galaxy that is closest to
the quasar sightline appears to be VCC339 (~L*/25) at 29/h_75 kpc and velocity
offset 292 km/s . A low surface brightness galaxy with the HI mass of the
sub-DLA absorber WSRT-J121921+0639 would likely have m_B ~ 17, and its diffuse
optical emission would need to compete with the light of both the background
QSO and a brighter foreground star ~10" from the QSO sight line.


title:
Toward a No-Go Theorem for an Accelerating Universe through a Nonlinear
  Backreaction

abstract:
  The backreaction of nonlinear inhomogeneities to the cosmic expansion is
re-analyzed in the framework of general relativity. Apparent discrepancies
regarding the effect of the nonlinear backreaction, which exist among the
results of previous works in different gauges, are resolved. By defining the
spatially averaged matter energy density as a conserved quantity in the large
comoving volume, it is shown that the nonlinear backreaction neither
accelerates nor decelerates the cosmic expansion in a matter-dominated
universe. The present result in the Newtonian gauge is consistent with the
previous results obtained in the comoving synchronous gauge. Although our work
does not give a complete proof, it strongly suggests the following no-go
theorem: No cosmic acceleration occurs as a result of the nonlinear
backreaction via averaging.


title: OSIRIS Software: The Mask Designer Tool

abstract:
  OSIRIS is a Day One instrument that will be available at the 10m GTC
telescope which is being built at La Palma observatory in the Canary Islands.
This optical instrument is designed to obtain wide-field narrow-band images
using tunable filters and to do low-resolution spectroscopy in both long-slit
and multislit modes. For the multislit spectroscopy mode, we have developed a
software to assist the observers to design focal plane masks. In this paper we
describe the characteristics of this Mask Designer tool. We discuss the main
design concepts, the functionality and particular features of the software.


title: Global albedo particles: a new approach from loss cone distributions

abstract:
  This paper has been withdraw by the author due to adding more modeling
results.


title: Detection of CO+ in the nucleus of M82

abstract:
  We present the detection of the reactive ion CO+ towards the prototypical
starburst galaxy M82. This is the first secure detection of this short-lived
ion in an external galaxy. Values of [CO+]/[HCO+]>0.04 are measured across the
inner 650pc of the nuclear disk of M82. Such high values of the [CO+]/[HCO+]
ratio had only been previously measured towards the atomic peak in the
reflection nebula NGC7023. This detection corroborates that the molecular gas
reservoir in the M82 disk is heavily affected by the UV radiation from the
recently formed stars. Comparing the column densities measured in M82 with
those found in prototypical Galactic photon-dominated regions (PDRs), we need
\~20 clouds along the line of sight to explain our observations. We have
completed our model of the molecular gas chemistry in the M82 nucleus. Our PDR
chemical model successfully explains the [CO+]/[HCO+] ratios measured in the
M~82 nucleus but fails by one order of magnitude to explain the large measured
CO+ column densities (~1--4x10^{13} cm^{-2}). We explore possible routes to
reconcile the chemical model and the observations.


title:
Double-core evolution and the formation of neutron-star binaries with
  compact companions

abstract:
  We present the results of a systematic exploration of an alternative
evolutionary scenario to form double neutron-star binaries, first proposed by
Brown (1995), which does not involve a neutron star passing through a common
envelope. In this scenario, the initial binary components have very similar
masses, and both components have left the main sequence before they evolve into
contact; preferably the primary has already developed a CO core. We have
performed population synthesis simulations to study the formation of double
neutron star binaries via this channel and to predict the orbital properties
and system velocities of such systems. We obtain a merger rate for DNSs in this
channel in the range of 0.1 - 12/Myr. These rates are still subject to
substantial uncertainties such as the modelling of the contact phase.


title: Flat-spectrum symmetric objects with ~1 kpc sizes I. The candidates

abstract:
  In order to understand the origin and evolution of radio galaxies, searches
for the youngest such sources have been conducted. Compact-medium symmetric
objects (CSO-MSOs) are thought to be the earliest stages of radio sources, with
possible ages of <10^3 yrs for CSOs (<1 kpc in size) and 10^4-10^5 yrs for MSOs
(1-15 kpc). From a literature selection in heterogeneous surveys, we have
established a sample of 37 confirmed CSOs. In addition, we only found three
confirmed flat-spectrum MSOs in the literature.
  The typical CSO resides on a z<0.5 galaxy, has a flat radio spectrum
(a_thin<0.5; S_v proportional to v^-a), is <0.3 kpc in size, has an arm length
ratio <2, and well-aligned (theta<20 deg) opposite lobes with a flux density
ratio <10. In order to populate the 0.3-1 kpc size range (large CSOs) and also
in order to find more flat-spectrum MSOs, we have built a sample of 157 radio
sources with a_{1.40}^{4.85}<0.5 that were resolved with the VLA-A 8.4 GHz. As
first results, we have 'rediscovered' nine of the known CSO/MSOs while
identifying two new ~14 kpc MSOs and two candidate CSO/MSOs (which only lack
redshifts for final classification). We were able to reject 61 of the remaining
144 objects from literature information alone. In the series of papers that
starts with this one we plan to classify the remaining 83 CSO/MSO candidates
(thanks to radio and optical observations) as well as characterize the physical
properties of the (likely) many 0.3-15 kpc flat-spectrum CSO/MSOs to be found.


title:
Titan at the time of the Cassini spacecraft first flyby: a prediction
  for its origin, bulk chemical composition and internal physical structure

abstract:
  I report the results of a new set of calculations for the gravitational
contraction of the proto-solar cloud to quantify the idea that Titan may be a
captured moon of Saturn (Prentice 1981, 1984). It is proposed that Titan
initially condensed as a secondary embryo in the same proto-solar gas ring from
which the central solid core and gaseous envelope of Saturn were acquired. At
the orbit of Saturn, the bulk chemical constituents of the condensate are rock
(mass fraction 0.494), water ice (0.474), and graphite (0.032). The mean
density is 1523 kg/m^3. Structural models for a frozen Titan yield a mean
density of 2095 kg/m^3 (chemically homogeneous case) and 1904 kg/m^3 (fully
differentiated 2-zone case). The agreement to one percent of the latter value
with the observed mean density suggests that Titan is indeed a fully
differentiated satellite. The value of C/MR^2 for this model is 0.316. It is
predicted that Titan has no internal ocean or induced magnetic field but it may
possess a small native dipole field of magnitude 2 x 10^11 Tesla m^3 due to
thermoremanent magnetization fed by the ancient magnetic field of Saturn.
Capture of Titan was achieved by gas drag at the edge of the proto-Saturnian
envelope at a time when that cloud had a radius close to the present orbital
size of Titan. Collisional drag was also probably an important agent in
securing the capture of Titan. Perhaps Hyperion is the shattered remnant of a
pre-existing native moon of Saturn that was destroyed on the arrival of Titan.
Titan should thus have much the same appearance as Triton, being nearly smooth,
crater-free and streaked with elemental carbon (Prentice 2004a).


title: Jet deceleration: the case of PKS 1136-135

abstract:
  Modeling the multiwavelength emission of successive regions in the jet of the
quasar PKS 1136-135 we find indication that the jet suffers deceleration near
its end. Adopting a continuous flow approximation we discuss the possibility
that the inferred deceleration is induced by entrainment of external gas.


title: ESO Imaging Survey: infrared observations of CDF-S and HDF-S

abstract:
  This paper presents infrared data obtained from observations carried out at
the ESO 3.5m New Technology Telescope (NTT) of the Hubble Deep Field South
(HDF-S) and the Chandra Deep Field South (CDF-S). These data were taken as part
of the ESO Imaging Survey (EIS) program, a public survey conducted by ESO to
promote follow-up observations with the VLT. In the HDF-S field the infrared
observations cover an area of ~53 square arcmin, encompassing the HST WFPC2 and
STIS fields, in the JHKs passbands. The seeing measured in the final stacked
images ranges from 0.79" to 1.22" and the median limiting magnitudes (AB
system, 2" aperture, 5sigma detection limit) are J_AB~23.0, H_AB~22.8 and
K_AB~23.0 mag. Less complete data are also available in JKs for the adjacent
HST NICMOS field. For CDF-S, the infrared observations cover a total area of
\~100 square arcmin, reaching median limiting magnitudes (as defined above) of
J_AB~23.6 and K_AB~22.7 mag. For one CDF-S field H-band data are also
available. This paper describes the observations and presents the results of
new reductions carried out entirely through the un-supervised, high-throughput
EIS Data Reduction System and its associated EIS/MVM C++-based image processing
library developed, over the past 5 years, by the EIS project and now publicly
available. The paper also presents source catalogs extracted from the final
co-added images which are used to evaluate the scientific quality of the survey
products, and hence the performance of the software. This is done comparing the
results obtained in the present work with those obtained by other authors from
independent data and/or reductions carried out with different software packages
and techniques. The final science-grade catalogs and co-added images are
available at CDS.


title:
"Soft bang" instead of "big bang": model of an inflationary universe
  without singularities and with eternal physical past time

abstract:
  The solution for an inflationary universe without singularities is derived
from the Einstein-Lemaitre equations. The present state of the universe evolved
from a steady state solution for a tiny, but classical micro-universe with
large cosmological constant or large equivalent vacuum energy density and with
an equal energy density of radiation and/or some kind of relativistic
primordial matter in the infinite past. An instability of this state outside
the quantum regime caused a "soft bang" by triggering an expansion that
smoothly started with zero expansion rate, continuously increased, culminated
in an exponentially inflating phase and ended through a phase transition, the
further evolution being a Friedmann-Lemaitre evolution as in big bang models.
As a necessary implication of the model the universe must be closed. All other
parameters of the model are very similar to those of big bang models and comply
with observational constraints.


title: Fourier resolved spectroscopy of 4U 1543-47 during the 2002 outburst

abstract:
  We have obtained Fourier-resolved spectra of the black-hole binary 4U 1543-47
in the canonical states (high/soft, very high, intermediate and low/hard)
observed in this source during the decay of an outburst that took place in
2002. Our objective is to investigate the variability of the spectral
components generally used to describe the energy spectra of black-hole systems,
namely a disk component, a power-law component attributed to Comptonization by
a hot corona and the contribution of the iron line due to reprocessing of the
high energy (E > 7 keV) radiation. We find that i) the disk component is not
variable on time scales shorter than ~100 seconds, ii) the reprocessing
emission as manifest by the variability of the Fe Kalpha line responds to the
primary radiation variations down to time scales of ~70 ms in the high and
very-high states, but longer than 2 s in the low state, iii) the low-frequency
QPOs are associated with variations of the X-ray power law spectral component
and not to the disk component and iv) the spectra corresponding to the highest
Fourier frequency are the hardest
  (show the flatter spectra) at a given spectral state. These results question
models that explain the observed power spectra as due to modulations of the
accretion rate alone, as such models do not provide any apparent reason for a
Fourier frequency dependence of the power law spectral indices.


title:
Testing the companion hypothesis for the origin of the X-ray emission
  from intermediate-mass main-sequence stars

abstract:
  There is no straightforward explanation for intrinsic X-ray emission from
intermediate-mass main-sequence stars. Therefore the observed emission is often
interpreted in terms of (hypothesized) late-type magnetically active companion
stars. We use Chandra imaging observations to spatially resolve in X-rays a
sample of main-sequence B-type stars with recently discovered companions at
arcsecond separation. We find that all spatially resolved companions are X-ray
emitters, but seven out of eleven intermediate-mass stars are also X-ray
sources. If this emission is interpreted in terms of additional sub-arcsecond
or spectroscopic companions, this implies a high multiplicity of B-type stars.
Firm results on B star multiplicity pending, the alternative, that B stars
produce intrinsic X-rays, can not be discarded. The appropriate scenario in
this vein is might be a magnetically confined wind, as suggested for the X-ray
emission of the magnetic Ap star IQ Aur. However, the only Ap star in the
Chandra sample is not detected in X-rays, and therefore does not support this
picture.


title:
The X-ray emission of the supernova remnant W49B observed with
  XMM-Newton

abstract:
  In the framework of the study of supernova remnants and their complex
interaction with the interstellar medium, we report on an XMM-Newton EPIC
observation of the Galactic supernova remnant W49B. We investigate the spatial
distribution of the chemical and physical properties of the plasma, so as to
get important constraints on the physical scenario, on the dynamics of the
supernova explosion, and on the interaction of the supernova remnant with the
ambient interstellar clouds. We present line images, equivalent width maps, and
a spatially resolved spectral analysis of a set of homogeneous regions. The
X-ray spectrum of W49B is characterized by strong K emission lines from Si, S,
Ar, Ca and Fe. In all the regions studied, the X-ray spectrum is dominated by
the emission from the ejecta and there is no indication of radial
stratification of the elements. A high overabundance of Ni
(Ni/Ni_sun=10^{+2}_{-1}) is required in the bright central region and the
previous detection of Cr and Mn line emission is confirmed. Spectra are well
described by two thermal components in collisional ionization equilibrium. We
observe spatial variations in the temperature, with the highest temperature
found in the east and the lowest in the west. Our results support a scenario in
which the X-ray emission comes from ejecta interacting with a dense belt of
ambient material, but another possibility is that the remnant is the result of
an asymmetric bipolar explosion with the eastern jet being hotter and more
Fe-rich than the western jet. The eastern jet is confined by interaction with
ambient molecular clouds. Comparison of the observed abundances with yields for
hypernova and supernova nucleosynthesis does not directly support the
association of W49B with a gamma-ray burst, although it remains possible.


title:
Non-Newtonian behavior in weak field general relativity for extended
  rotating sources

abstract:
  Exact stationary axially symmetric solutions of the 4D Einstein equations
with corotating pressureless perfect fluid sources are studied. A particular
solution with approximately flat rotation curve is discussed in some detail. We
find that simple Newtonian arguments overestimate the amount of matter needed
to explain these curves by more than 30%. The crucial insight gained by this
model is that the Newtonian approximation breaks down globally, even though it
is valid locally everywhere. No conflict with solar system tests arises.


title:
Response of the integrals in the Tremaine-Weinberg method to multiple
  pattern speeds: a counter-rotating inner bar in NGC 2950?

abstract:
  When integrals in the standard Tremaine-Weinberg method are evaluated for the
case of a realistic model of a doubly barred galaxy, their modifications
introduced by the second rotating pattern are in accord with what can be
derived from a simple extension of that method, based on separation of tracer's
density. This extension yields a qualitative argument that discriminates
between prograde and retrograde inner bars. However, the estimate of the value
of inner bar's pattern speed requires further assumptions. When this extension
of the Tremaine-Weinberg method is applied to the recent observation of the
doubly barred galaxy NGC 2950, it indicates that the inner bar there is
counter-rotating, possibly with the pattern speed of -140 +/- 50 km/s/arcsec.
The occurrence of counter-rotating inner bars can constrain theories of galaxy
formation.


title: A Tracker Solution for a Holographic Dark Energy Model

abstract:
  We investigate a kind of holographic dark energy model with the future event
horizon the IR cutoff and the equation of state -1. In this model, the
constraint on the equation of state automatically specifies an interaction
between matter and dark energy. With this interaction included, an accelerating
expansion is obtained as well as the transition from deceleration to
acceleration. It is found that there exists a stable tracker solution for the
numerical parameter $d>1$, and $d$ smaller than one will not lead to a physical
solution. This model provides another possible phenomenological framework to
alleviate the cosmological coincidence problem in the context of holographic
dark energy. Some properties of the evolution which are relevant to
cosmological parameters are also discussed.


title: Chandra Observations of the Transient 7-s X-ray Pulsar AX J1845.0-0258

abstract:
  We present the results of Chandra X-ray Observatory observations of the
transient anomalous X-ray pulsar (AXP) candidate AX J1845.0-0258 in apparent
quiescence. Within the source's error circle, we find a point source and
possible counterpart, which we designate CXOU J184454.6-025653. No coherent
pulsations are detected, and no extended emission is seen. The source's
spectrum is equally well described by a blackbody model of temperature kT~2.0
keV or a power law model with photon index Gamma~1.0. This is considerably
harder than was seen for AX J1845.0-0258 during its period of brightening in
1993 (kT~0.6 keV) despite being at least ~13 times fainter. This behavior is
opposite to that observed in the case of the established transient AXP, XTE
J1810-197. We therefore explore the possibility that CXOU J184454.6-025653 is
an unrelated source, and that AX J1845.0-0258 remains undetected since 1993,
with flux 260-430 times fainter than at that epoch. If so, this would represent
an unprecedented range of variability in AXPs.


title:
Tracing early structure formation with massive starburst galaxies and
  their implications for reionization

abstract:
  Cosmological hydrodynamic simulations have significantly improved over the
past several years, and we have already shown that the observed properties of
Lyman-break galaxies (LBGs) at z=3 can be explained well by the massive
galaxies in the simulations. Here we extend our study to z=6 and show that we
obtain good agreement for the LBGs at the bright-end of the luminosity function
(LF). Our simulations also suggest that the cosmic star formation rate density
has a peak at z= 5-6, and that the current LBG surveys at z=6 are missing a
significant number of faint galaxies that are dimmer than the current magnitude
limit. Together, our results suggest that the universe could be reionized at
z=6 by the Pop II stars in ordinary galaxies. We also estimate the LF of
Lyman-alpha emitters (LAEs) at z=6 by relating the star formation rate in the
simulation to the Ly-alpha luminosity. We find that the simulated LAE LFs agree
with the observed data provided that the net escape fraction of Ly-alpha photon
is f_{Ly-alpha} <= 0.1. We investigate two possible scenarios for this effect:
(1) all sources in the simulation are uniformly dimmer by a factor of 10
through attenuation, and (2) one out of ten LAEs randomly lights up at a given
moment. We show that the correlation strength of the LAE spatial distribution
can possibly distinguish the two scenarios.


title: The Size of the Cooling Region of Hot Gas in Two Elliptical Galaxies

abstract:
  Some early-type galaxies show OVI emission, a tracer of gas at 10^5.5 K, and
a predicted product of gas cooling from the X-ray emitting temperatures. We
studied the spatial extent and velocity structure of this cooling gas by
obtaining spectra of the OVI doublet in NGC 4636 and NGC 5846 with the Far
Ultraviolet Spectroscopic Explorer. For NGC 4636, the central LWRS pointing
shows that the OVI lines are double-peaked and symmetrical about the systemic
velocity of the galaxy, with a separation of 210 km/s. A LWRS observation 30"
from the center failed to show additional OVI emission. For NGC 5846, three
spectra were obtained with 4" x 20" apertures (MDRS) at the center and 4" to
the east and west of the center. The OVI line flux seen in the previous LWRS is
contained in the sum of the smaller apertures, with most of the flux in a
single non-central MDRS aperture, suggesting a size for the emission < 0.5 kpc;
the emission consists of a blue and red peak. For both galaxies, the OVI
velocity structure is similar to that of the optical [NII] emission and is
consistent with rotation. The compactness and velocity structure of the OVI
emission rules out cooling flow models with broadly distributed mass drop-out
but is consistent with cooling flow models where the cooling occurs primarily
in the central region. The 1E4 K gas may be the end state of the OVI gas.


title: X-Ray Flares from Postmerger Millisecond Pulsars

abstract:
  Recent observations support the suggestion that short-duration gamma-ray
bursts are produced by compact star mergers. The X-ray flares discovered in two
short gamma-ray bursts last much longer than the previously proposed postmerger
energy release time scales. Here we show that they can be produced by
differentially rotating, millisecond pulsars after the mergers of binary
neutron stars. The differential rotation leads to windup of interior poloidal
magnetic fields and the resulting toroidal fields are strong enough to float up
and break through the stellar surface. Magnetic reconnection--driven explosive
events then occur, leading to multiple X-ray flares minutes after the original
gamma-ray burst.


title:
Accelerated Cosmological Models in Modified Gravity tested by distant
  Supernovae SNIa data

abstract:
  Recent supernovae of type Ia measurements and other astronomical observations
suggest that our universe is in accelerating phase of evolution at the present
epoch. While a dark energy of unknown form is usually proposed as the most
feasible mechanism for the acceleration, there are appears some alternative
conception that some effects arising from generalization of Einstein equation
can mimic dark energy through a modified Friedmann equation. In this work we
investigate some observational constraints on modified Friedmann equation
obtained from generalized Lagrangian ${\cal L} \propto R^n$ in minimal coupling
with matter in Palatini formalism. We mainly concentrate on the constraints of
model parameters from distant supernovae but other constraint from baryon
oscillation prior is also considered. We obtain the confidence levels on two
additional model parameter ($n$,$\Omega_{m,0}$). We conclude that the FRW model
of First-Order Non-linear gravity survives several observational test like SNIa
observation and baryon oscillation peaks. We find preferred value of
$\Omega_{m,0} \simeq 0.3$ from combined analysis of supernovae data and baryon
oscillation peak. For deeper statistical analysis we apply Akaike and Bayesian
information criteria of model selection for comparison prediction of the model
with prediction of concordance $\Lambda$CDM model.


title: On the Lack of a Soft X-Ray Excess from Clusters of Galaxies

abstract:
  A soft X-ray excess has been claimed to exist in and around a number of
galaxy clusters and this emission has been attributed to the warm-hot
intergalactic medium that may constitute most of the baryons in the local
universe. We have re-examined a study of the XMM-Newton observations on this
topic by Kaastra et al. (2003) and find that the X-ray excess (or deficit)
depends upon Galactic latitude and appears to be most closely related to the
surface brightness of the 1/4 keV emission, which is largely due to emission
from the Local hot bubble and the halo of the Milky Way. We suggest that the
presence of the soft X-ray excess is due to incorrect subtraction of the soft
X-ray background. An analysis is performed where we choose a 1/4 keV background
that is similar to the background near the cluster (and for similar HI column).
We find that the soft X-ray excess largely disappears using our background
subtraction and conclude that these soft X-ray excesses are not associated with
the target clusters. We also show that the detections of "redshifted" O VII
lines claimed by Kaastra et al. (2003) are correlated with solar system charge
exchange emission suggesting that they are not extragalactic either.


title: CMB Polarization due to Scattering in Clusters

abstract:
  Scattering of the cosmic microwave background (CMB) in clusters of galaxies
polarizes the radiation. We explore several polarization components which have
their origin in the kinematic quadrupole moments induced by the motion of the
scattering electrons, either directed or random. Polarization levels and
patterns are determined in a cluster simulated by the hydrodynamical Enzo code.
We find that polarization signals can be as high as $\sim 1 \mu$K, a level that
may be detectable by upcoming CMB experiments.


title:
Timing Features of the Accretion--driven Millisecond X-Ray Pulsar XTE
  J1807--294 in 2003 March Outburst

abstract:
  In order to probe the activity of the inner disk flow and its effect on the
neutron star surface emissions, we carried out the timing analysis of the Rossi
X-Ray Timing Explorer (RXTE) observations of the millisecond X-ray pulsar XTE
J1807--294, focusing on its correlated behaviors in X-ray intensities, hardness
ratios, pulse profiles and power density spectra. The source was observed to
have a serial of broad "puny" flares on a timescale of hours to days on the top
of a decaying outburst in March 2003. In the flares, the spectra are softened
and the pulse profiles become more sinusoidal. The frequency of kilohertz
quasi-periodic oscillation (kHz QPO) is found to be positively related to the
X-ray count rate in the flares. These features observed in the flares could be
due to the accreting flow inhomogeneities. It is noticed that the fractional
pulse amplitude increases with the flare intensities in a range of $\sim
2%-14%$, comparable to those observed in the thermonuclear bursts of the
millisecond X-ray pulsar XTE J1814--338, whereas it remains at about 6.5% in
the normal state. Such a significant variation of the pulse profile in the
"puny" flares may reflect the changes of physical parameters in the inner disk
accretion region. Furthermore, we noticed an overall positive correlation
between the kHz QPO frequency and the fractional pulse amplitude, which could
be the first evidence representing that the neutron-star surface emission
properties are very sensitive to the disk flow inhomogeneities. This effect
should be cautiously considered in the burst oscillation studies.


title: The parallel lives of supermassive black holes and their host galaxies

abstract:
  We compare all the available observational data on the redshift evolution of
the total stellar mass and star formation rate density in the Universe with the
mass and accretion rate density evolution of supermassive black holes,
estimated from the hard X-ray selected luminosity function of quasars and
active galactic nuclei. We find that on average black hole mass must have been
higher at higher redshift for given spheroid stellar mass. Moreover, we find
negative redshift evolution of the disk/irregulars to spheroid mass ratio. The
total accretion efficiency is constrained to be between 0.06 and 0.12,
depending on the exact value of the local SMBH mass density, and on the
critical accretion rate below which radiatively inefficient accretion may take
place.


title:
A Spitzer mid-infrared spectral survey of mass-losing carbon stars in
  the Large Magellanic Cloud

abstract:
  We present a Spitzer Space Telescope spectroscopic survey of mass-losing
carbon stars (and one oxygen-rich star) in the Large Magellanic Cloud. The
spectra cover the wavelength range 5--38 micron. They show varying combinations
of dust continuum, dust emission features (SiC, MgS) and molecular absorption
bands (C2H2, HCN). A set of four narrow bands, dubbed the Manchester system, is
used to define the infrared continuum for dusty carbon stars. The relations
between the continuum colours and the strength of the dust and molecular
features are studied, and are compared to Galactic stars of similar colours.
The circumstellar 7-micron C2H2 band is found to be stronger at lower
metallicity, from a comparison of stars in the Galaxy, the LMC and the SMC.
This is explained by dredge-up of carbon, causing higher C/O ratios at low
metallicity (less O). A possible 10-micron absorption feature seen in our
spectra may be due to C3. This band has also been identified with interstellar
silicate or silicon-nitrite dust. The line-to-continuum ratio of theSiC and MgS
bands shows some indication of being lower at low metallicity. The MgS band is
only seen at dust temperatures below 600 K. We discuss the selection of carbon
versus oxygen-rich AGB stars using the J-K vs. K-A colours, and show that these
colours are relatively insensitive to chemical type. Metal-poor carbon stars
form amorphous carbon dust from self-produced carbon. The formation efficiency
of oxygen-rich dust depends more strongly on metallicity. We suggest that in
lower-metallicity environments, the dust input into the Interstellar Medium by
AGB stars is efficient but may be strongly biassed towards carbonaceous dust,
as compare to the Galaxy.


title:
Folded Fields as the Source of Extreme Radio-Wave Scattering in the
  Galactic Center

abstract:
  A strong case has been made that radio waves from sources within about half a
degree of the Galactic Center undergo extreme diffractive scattering. However,
problems arise when standard (``Kolmogorov'') models of electron density
fluctuations are employed to interpret the observations of scattering in
conjunction with those of free-free radio emission. Specifically, the outer
scale of a Kolmogorov spectrum of electron density fluctuations is constrained
to be so small that it is difficult to identify an appropriate astronomical
setting. Moreover, an unacceptably high turbulent heating rate results if the
outer scale of the velocity field coincides with that of the density
fluctuations. We propose an alternative model based on folded magnetic field
structures that have been reported in numerical simulations of small-scale
dynamos. Nearly isothermal density variations across thin current sheets
suffice to account for the scattering. There is no problem of excess turbulent
heating because the outer scale for the velocity fluctuations is much larger
than the widths of the current sheets. We speculate that interstellar magnetic
fields could possess geometries that reflect their origins: fields maintained
by the galactic dynamo could have large correlation lengths, whereas those
stirred by local energetic events might exhibit folded structures.


title:
VIRGO sensitivity to binary coalescences and the Population III black
  hole binaries

abstract:
  We analyze the properties of VIRGO detector with the aim of studying its
ability to search for coalescing black hole binaries. We focus on the remnants
of the Population III stars, which currently should be massive black holes
($\sim 100-1000 M_\odot$), some of them bound in binary systems. The
coalescence of such binaries due to emission of gravitational waves may be
currently observable. We use a binary population synthesis to model the
evolution of Population III binaries. We calculate the signal to noise ratios
of gravitational waves emitted by the system in each of the coalescence phase:
inspiral, merger and ringdown, and provide simple formulae for the signal to
noise ratio as a function of masses of the binaries. We estimate the detection
rates for the VIRGO interferometer and also compare them with the estimates for
the current LIGO. We show that these expected rates are similar to, or larger
than the expected rates from coalescences of Population I and II compact object
binaries.


title: Observation of kink waves in solar spicules

abstract:
  Height series of H${\alpha}$ spectra in solar limb spicules obtained with the
53 cm coronagraph of the Abastumani Astrophysical Observatory are analyzed.
Each height series covered 8 different heights beginning at 3800 km above the
photosphere. The spatial difference between neighboring heights was 1$^{\prime
\prime}$, consequently $\sim$ 3800 - 8700 km distance above the photosphere has
been covered. The total time duration of each height series was 7 s. We found
that nearly 20% of measured height series show a periodic spatial distribution
of Doppler velocities. We suggest that this spatial periodicity in Doppler
velocity is caused by propagating kink waves in spicules. The wave length is
found to be $\sim$ 3500 km. However the wave length tends to be $\sim$ 1000 km
at the photosphere due to the height variation of the kink speed. This probably
indicates to a granular origin for the waves. The period of waves is estimated
to be in the range of 35-70 s. These waves may carry photospheric energy into
the corona, therefore can be of importance in coronal heating.


title: Two-wave interaction in ideal magnetohydrodynamics

abstract:
  The weakly nonlinear interaction of sound and linearly polarised Alfv{\'e}n
waves propagating in the same direction along an applied magnetic field is
studied. It is found that a sound wave is coupled to the Alfv{\'e}n wave with
double period and wavelength when the sound and Alfv{\'e}n speeds are equal.
The Alfv{\'e}n wave drives the sound wave through the ponderomotive force,
while the sound wave returns energy back to the Alfv{\'e}n wave through the
parametric (swing) influence. As a result, the two waves alternately exchange
their energy during propagation. The process of energy exchange is faster for
waves with stronger amplitudes. The phenomenon can be of importance in
astrophysical plasmas, including the solar atmosphere and solar wind.


title: Depolarization canals and interstellar turbulence

abstract:
  Recent radio polarization observations have revealed a plethora of unexpected
features in the polarized Galactic radio background that arise from propagation
effects in the random (turbulent) interstellar medium. The canals are
especially striking among them, a random network of very dark, narrow regions
clearly visible in many directions against a bright polarized Galactic
synchrotron background. There are no obvious physical structures in the ISM
that may have caused the canals, and so they have been called Faraday ghosts.
They evidently carry information about interstellar turbulence but only now is
it becoming clear how this information can be extracted. Two theories for the
origin of the canals have been proposed; both attribute the canals to Faraday
rotation, but one invokes strong gradients in Faraday rotation in the sky plane
(specifically, in a foreground Faraday screen) and the other only relies on
line-of-sight effects (differential Faraday rotation). In this review we
discuss the physical nature of the canals and how they can be used to explore
statistical properties of interstellar turbulence. This opens studies of
magnetized interstellar turbulence to new methods of analysis, such as contour
statistics and related techniques of computational geometry and topology. In
particular, we can hope to measure such elusive quantities as the Taylor
microscale and the effective magnetic Reynolds number of interstellar MHD
turbulence.


title: Toward a Clean Sample of Ultra-Luminous X-ray Sources

abstract:
  CONTEXT. Observational follow-up programmes for the characterization of
ultra-luminous X-ray sources (ULXs) require the construction of clean samples
of such sources in which the contamination by foreground/background sources is
minimum.
  AIMS. In this article we calculate the degree of foreground/background
contaminants among the ULX sample candidates in the Colbert & Ptak (2002)
catalogue and compare these computations with available spectroscopical
identifications.
  METHODS. We use statistics based on known densities of X-ray sources and
AGN/QSOs selected in the optical. The analysis is done individually for each
parent galaxy. The existing identifications of the optical counterparts are
compiled from the literature.
  RESULTS. More than a half of the ULXs, within twice the distance of the major
axis of the 25 mag/arcsec$^2$ isophote from RC3 nearby galaxies and with X-ray
luminosities $L_X$[2-10 keV] $\ge 10^{39}$ erg/s, are expected to be high
redshift background QSOs. A list of 25 objects (clean sample) confirmed to be
real ULXs or to have a low probability of being contaminant
foreground/background objects is provided.


title:
Effect of hyperon-hyperon interaction on bulk viscosity and r-mode
  instability in neutron stars

abstract:
  We investigate the effect of hyperon matter including hyperon-hyperon
interaction on bulk viscosity. Equations of state are constructed within the
framework of a relativistic field theoretical model where baryon-baryon
interaction is mediated by the exchange of scalar and vector mesons.
Hyperon-hyperon interaction is also taken into account by the exchange of two
strange mesons. This interaction results in a smaller maximum mass neutron star
compared with the case without the interaction. The coefficient of bulk
viscosity due to the non-leptonic weak process is determined by these equations
of state. The interacting hyperon matter reduces the bulk viscosity coefficient
in a neutron star interior compared with the no interaction case. The r-mode
instability is more effectively suppressed in hyperon-hyperon interaction case
than that without the interaction.


title: Galaxy cluster merger kinematics by Rees-Sciama effect

abstract:
  We discuss how to use the Rees-Sciama (RS) effect associated with merging
clusters of galaxies to measure their kinematic properties. In a previous work
(Rubino-Martin et al. 2004), the morphology and symmetries of the effect were
examined by means of a simplified model. Here, we use realistic N-body
simulations to better describe the effect, and to confirm that the signal has a
characteristic quadrupole structure. From the amplitude of the signal obtained,
we conclude that it is necessary to combine several cluster mergers in order to
achieve a detection. Using the extended Press-Schechter formalism, we
characterized the expected distribution of the parameters describing the
mergers, and we used these results to generate realistic mock catalogues of
cluster mergers. To optimize the extraction of the RS signal, we developed an
extension of the spatial filtering method described in Haehnelt & Tegmark
(1996). This extended filter has a general definition, so it can be applied in
many other fields, such as gravitational lensing of the CMB or lensing of
background galaxies. It has been applied to our mock catalogues, and we show
that with the announced sensitivities of future experiments like the Atacama
Cosmology Telescope (ACT), the South Pole Telescope (SPT) or the Atacama Large
Millimeter Array (ALMA), a detection of the signal will be possible if we
consider of the order of 1,000 cluster mergers.


title: Frustrated Expectations: Defect Networks and Dark Energy

abstract:
  We discuss necessary conditions for a network of cosmic domain walls to have
a chance of providing the dark energy that might explain the recent
acceleration of the universe. We derive a strong bound on the curvature of the
walls, which shows that viable candidate networks must be fine-tuned and
non-standard. We also discuss various requirements that any stable lattice of
frustrated walls must obey. We conjecture that, even though one can build (by
hand) lattices that would be stable, no such lattices will ever come out of
realistic domain wall forming cosmological phase transitions. We provide some
simple numerical simulations that illustrate our results and correct some
misconceptions in the published literature, but a detailed numerical analysis
is left for a companion paper.


title: GRB051210: Swift detection of a short gamma ray burst

abstract:
  The short/hard GRB051210 was detected and located by the Swift-BAT instrument
and rapidly pointed towards by the narrow field instrumens. The XRT was able to
observe a bright X-ray afterglow, one of the few ever observed for this class
of bursts. We present the analysis of the prompt and afterglow emission of this
event The BAT spectrum is a power-law with photon index 1.1 +/-0.3. The X-ray
light curve decays with slope 2.58+/-0.11 and shows a small flare in the early
phases. The spectrum can be described with a power law with photon index
1.54+/-0.16 and absorption (7.5 (-3.2, +4.3)*10^20 cm-2 We find that the X-ray
emission is consistent with the hypothesis that we are observing the curvature
effect of a GRB occurred in a low density medium, with no detectable afterglow.
We estimate the density of the circumburst medium to be lower than 4*10^-3
cm^-3. We also discuss different hypothesis on the possible origin of the
flare.


title: The COMPLETE Survey of Star-Forming Regions: Phase I Data

abstract:
  We present an overview of data available for the Ophiuchus and Perseus
molecular clouds from ``Phase I'' of the COMPLETE Survey of Star-Forming
Regions. This survey provides a range of data complementary to the Spitzer
Legacy Program ``From Molecular Cores to Planet Forming Disks.'' Phase I
includes: Extinction maps derived from 2MASS near-infrared data using the NICER
algorithm; extinction and temperature maps derived from IRAS 60 and 100um
emission; HI maps of atomic gas; 12CO and 13CO maps of molecular gas; and
submillimetre continuum images of emission from dust in dense cores. Not
unexpectedly, the morphology of the regions appears quite different depending
on the column-density tracer which is used, with IRAS tracing mainly warmer
dust and CO being biased by chemical, excitation and optical depth effects.
Histograms of column-density distribution are presented, showing that
extinction as derived from 2MASS/NICER gives the closest match to a log-normal
distribution as is predicted by numerical simulations. All the data presented
in this paper, and links to more detailed publications on their implications
are publically available at the COMPLETE website.


title: Pluto's moon system: survey of the phase space I

abstract:
  The dynamical structure of the phase space of the Pluto--Charon system is
studied in the model of the spatial circular restricted three-body problem by
using numerical methods. With the newly discovered two small satellites S/2005
P1 and S/2005 P2, the Pluto--Charon system can be considered as the first known
binary system in which celestial bodies move in P-type orbits. It is shown that
the two satellites are in the stable region of the phase space and their origin
by capture is unlikely. Also the large mass parameter allows to regard the
satellites as a model of a new class of exoplanets orbiting around stellar
binary systems.


title: Effect of heat flux on differential rotation in turbulent convection

abstract:
  We studied the effect of the turbulent heat flux on the Reynolds stresses in
a rotating turbulent convection. To this end we solved a coupled system of
dynamical equations which includes the equations for the Reynolds stresses, the
entropy fluctuations and the turbulent heat flux. We used a spectral $\tau$
approximation in order to close the system of dynamical equations. We found
that the ratio of the contributions to the Reynolds stresses caused by the
turbulent heat flux and the anisotropic eddy viscosity is of the order of $\sim
10 (L_\rho / l_0)^2$, where $l_{0}$ is the maximum scale of turbulent motions
and $L_\rho$ is the fluid density variation scale. This effect is crucial for
the formation of the differential rotation and should be taken into account in
the theories of the differential rotation of the Sun, stars and planets. In
particular, we demonstrated that this effect may cause the differential
rotation which is comparable with the typical solar differential rotation.


title:
Cloud fragmentation and proplyd-like features in HII regions imaged by
  HST

abstract:
  We have analyzed HST ACS and WFPC2 new and archival images of eight HII
regions to look for new proto-planetary disks (proplyds) similar to those found
in the Orion Nebula. We find a wealth of features similar in size (though many
are larger) to the bright cusps around the Orion Nebula proplyds. None of them,
however, contains a definitive central star. From this, we deduce that the new
cusps may not be proplyds, but instead are fragments of molecular cloud
material. Out of all the features found in the eight HII regions examined, only
one, an apparent edge-on silhouette in M17, may have a central star. This
feature might join the small number of bona fide proplyds found outside the
Orion Nebula, in M8, M20 and possibly in M16. In line with the results found
recently by Smith et al. (2005), the paucity of proplyds outside the Orion
Nebula, may be explained by their transient nature as well as by the specific
environmental conditions under whichthey can be observed.


title: Mid-Infrared Ethane Emission on Neptune and Uranus

abstract:
  We report 8- to 13-micron spectral observations of Neptune and Uranus from
the NASA Infrared Telescope Facility spanning more than a decade. The
spectroscopic data indicate a steady increase in Neptune's mean atmospheric
12-micron ethane emission from 1985 to 2003, followed by a slight decrease in
2004. The simplest explanation for the intensity variation is an increase in
stratospheric effective temperature from 155 +/- 3 K in 1985 to 176 +/- 3 K in
2003 (an average rate of 1.2 K/year), and subsequent decrease to 165 +/- 3 K in
2004. We also detected variation of the overall spectral structure of the
ethane band, specifically an apparent absorption structure in the central
portion of the band; this structure arises from coarse spectral sampling
coupled with a non-uniform response function within the detector elements. We
also report a probable direct detection of ethane emission on Uranus. The
deduced peak mole fraction is approximately an order of magnitude higher than
previous upper limits for Uranus. The model fit suggests an effective
temperature of 114 +/- 3 K for the globally-averaged stratosphere of Uranus,
which is consistent with recent measurements indicative of seasonal variation.


title:
Discovery of Lyman-alpha Pumped Molecular Hydrogen Emission in the
  Planetary Nebulae NGC 6853 and NGC 3132

abstract:
  We report the first observation of Ly$\alpha$ pumped molecular hydrogen
emission lines in planetary nebulae. The H$_{2}$ emission observed in the
ultraviolet spectra of NGC 6853 and NGC 3132 can be explained by excitation of
vibrationally hot H$_{2}$ by Ly$\alpha$ photons. Constraints are placed on the
nebular Ly$\alpha$ emission profile, as well as the molecular hydrogen
temperature, column density and turbulent motion. These parameters are similar
for the two nebulae, pointing to similar physical conditions in these objects.
The ro-vibrational cascade following Ly$\alpha$ pumping is predicted to have
low surface brightness signatures in the visible and near infrared.


title:
The Effect of Large-Scale Structure on the SDSS Galaxy Three-Point
  Correlation Function

abstract:
  We present measurements of the normalised redshift-space three-point
correlation function (Q_z) of galaxies from the Sloan Digital Sky Survey (SDSS)
main galaxy sample. We have applied our "npt" algorithm to both a
volume-limited (36738 galaxies) and magnitude-limited sample (134741 galaxies)
of SDSS galaxies, and find consistent results between the two samples, thus
confirming the weak luminosity dependence of Q_z recently seen by other
authors. We compare our results to other Q_z measurements in the literature and
find it to be consistent within the full jack-knife error estimates. However,
we find these errors are significantly increased by the presence of the ``Sloan
Great Wall'' (at z ~ 0.08) within these two SDSS datasets, which changes the
3-point correlation function (3PCF) by 70% on large scales (s>=10h^-1 Mpc). If
we exclude this supercluster, our observed Q_z is in better agreement with that
obtained from the 2dFGRS by other authors, thus demonstrating the sensitivity
of these higher-order correlation functions to large-scale structures in the
Universe. This analysis highlights that the SDSS datasets used here are not
``fair samples'' of the Universe for the estimation of higher-order clustering
statistics and larger volumes are required. We study the shape-dependence of
Q_z(s,q,theta) as one expects this measurement to depend on scale if the large
scale structure in the Universe has grown via gravitational instability from
Gaussian initial conditions. On small scales (s <= 6h^-1 Mpc), we see some
evidence for shape-dependence in Q_z, but at present our measurements are
consistent with a constant within the errors (Q_z ~ 0.75 +/- 0.05). On scales
>10h^-1 Mpc, we see considerable shape-dependence in Q_z.


title:
The relation between accretion rate and jet power in X-ray luminous
  elliptical galaxies

abstract:
  Using Chandra X-ray observations of 9 nearby, X-ray luminous ellipticals with
good optical velocity dispersion measurements, we show that a tight correlation
exists between the Bondi accretion rates calculated from the X-ray data and
estimated black hole masses, and the power emerging from these systems in
relativistic jets. The jet powers, inferred from the energies and timescales
required to inflate the cavities observed in the surrounding X-ray emitting
gas, can be related to the accretion rates by a power law model. A significant
fraction (2.2^{+1.0}_{-0.7} per cent, for P_jet=10^{43} erg/s) of the energy
associated with the rest mass of material entering the accretion radius
eventually emerges in the jets. The data also hint that this fraction may rise
slightly with increasing jet power. Our results have significant implications
for studies of accretion, jet formation and galaxy formation. The tight
correlation between P_Bondi and P_jet suggests that the Bondi formulae provide
a reasonable description of the accretion process, despite the likely presence
of magnetic pressure and angular momentum in the accreting gas, and that the
accretion flows are approximately stable over timescales of a few million
years. Our results show that the black hole `engines' at the hearts of large
elliptical galaxies and groups can feed back sufficient energy to stem cooling
and star formation, leading naturally to the observed exponential cut off at
the bright end of the galaxy luminosity function.


title:
An Exploratory Chandra Survey of a Well-Defined Sample of 35 Large
  Bright Quasar Survey Broad Absorption Line Quasars

abstract:
  We present 4-7 ks Chandra observations of 35 Broad Absorption Line (BAL)
quasars from the Large Bright Quasar Survey, the largest sample of sensitive,
0.5-8.0 keV X-ray observations of this class of quasars to date. The limited
ranges in both redshift (z=1.42-2.90) and UV luminosity (a factor of ~12) of
the sample also make it relatively uniform. Of 35 targets, 27 are detected for
a detection fraction of 77%, and we confirm previous studies that find BAL
quasars to be generally X-ray weak. Five of the eight non-detections are known
low-ionization BAL quasars, confirming reports of extreme X-ray weakness in
this subset (~10% of optically selected BAL quasars). Those BAL quasars with
the hardest X-ray spectra are also the X-ray weakest, consistent with the
interpretation that intrinsic absorption is the primary cause of X-ray weakness
in this class of quasars as a whole. Furthermore, the observed trend is not
consistent with simple neutral absorption, supporting findings from
spectroscopic observations of individual targets that BAL quasars typically
exhibit complex X-ray absorption (e.g., partially covering or ionized
absorbers). In sum, high-ionization BAL quasars are typically neither
intrinsically X-ray weak nor suffer from Compton-thick absorption. In general,
we find no evidence for correlations between X-ray weakness and UV
absorption-line properties, with the exception of a likely correlation between
the maximum outflow velocity of CIV absorption and the magnitude of X-ray
weakness. We discuss the implications of our results for disk-wind models of
BAL outflows in quasars. (abridged)


title: Short-lived Nuclei in the Early Solar System: Possible AGB Sources

abstract:
  (Abridged) We review abundances of short-lived nuclides in the early solar
system (ESS) and the methods used to determine them. We compare them to the
inventory for a uniform galactic production model. Within a factor of two,
observed abundances of several isotopes are compatible with this model. I-129
is an exception, with an ESS inventory much lower than expected. The isotopes
Pd-107, Fe-60, Ca-41, Cl-36, Al-26, and Be-10 require late addition to the
solar nebula. Be-10 is the product of particle irradiation of the solar system
as probably is Cl-36. Late injection by a supernova (SN) cannot be responsible
for most short-lived nuclei without excessively producing Mn-53; it can be the
source of Mn-53 and maybe Fe-60. If a late SN is responsible for these two
nuclei, it still cannot make Pd-107 and other isotopes. We emphasize an AGB
star as a source of nuclei, including Fe-60 and explore this possibility with
new stellar models. A dilution factor of about 4e-3 gives reasonable amounts of
many nuclei. We discuss the role of irradiation for Al-26, Cl-36 and Ca-41.
Conflict between scenarios is emphasized as well as the absence of a global
interpretation for the existing data. Abundances of actinides indicate a
quiescent interval of about 1e8 years for actinide group production in order to
explain the data on Pu-244 and new bounds on Cm-247. This interval is not
compatible with Hf-182 data, so a separate type of r-process is needed for at
least the actinides, distinct from the two types previously identified. The
apparent coincidence of the I-129 and trans-actinide time scales suggests that
the last actinide contribution was from an r-process that produced actinides
without fission recycling so that the yields at Ba and below were governed by
fission.


title:
Tentative Discovery of a New Supernova Remnant in Cepheus: Unveiling an
  Elusive Shell in the Spitzer Galactic First Look Survey

abstract:
  We have discovered an axially symmetric, well-defined shell of material in
the constellation of Cepheus, based on imaging acquired as part of the Galactic
First Look Survey with the Spitzer Space Telescope. The 86'' x 75'' object
exhibits brightened limbs on the minor axis, and is clearly visible at 24
microns, but is not detected in the 3.6, 4.5, 5.8, 8.0, 70, or 160 micron
images. Followup with 7.5 - 40 micron spectroscopy reveals the shell to be
composed entirely of ionized gas, and that the 24 micron imaging traces solely
[O IV] 25.89 micron emission. The spectrum also exhibits weaker [Ne III], [S
III], and very weak [Ne V] emission. No emission from warm dust is detected.
Spectral cuts through the center of the shell and at the northern limb are
highly consistent with each other. The progenitor is not readily identified,
but with scaling arguments and comparison to well-known examples of evolved
stellar objects, we find the observations to be most straightforward to
interpret in terms of a young supernova remnant located at a distance of at
least 10 kpc, some 400 pc above the Galactic disk. If confirmed, this would be
the first SNR discovered initially at infrared wavelengths.


title: A high resolution UV absorption spectrum of supernova ejecta in SN1006

abstract:
  We report a high resolution, far-ultraviolet, STIS E140M spectrum of the
strong, broad Si II, III, and IV features produced by the ejecta of SN1006 seen
in absorption against the background Schweizer-Middleditch star. The spectrum
confirms the extreme sharpness of the red edge of the redshifted Si II 1260 A
feature, supporting the idea that this edge represents the location of the
reverse shock moving into the freely expanding ejecta. The expansion velocity
of ejecta at the reverse shock is measured to be 7026 +-3(relative)
+-10(absolute) km/s. If the shock model is correct, then the expansion velocity
should be decreasing at the observable rate of 2.7 +-0.1 km/s per year. The
pre-shock velocity, post-shock velocity, and post-shock velocity dispersion are
all measured from the Si II 1260 A feature, and consistency of these velocities
with the shock jump conditions implies that there is little or no electron
heating in this fast (2680 km/s) Si-rich shock.


title:
Powerful High Velocity-Dispersion Molecular Hydrogen Associated with an
  Intergalactic Shock Wave in Stephan's Quintet

abstract:
  We present the discovery of strong mid-infrared emission lines of molecular
hydrogen of apparently high velocity dispersion (~870 km/s) originating from a
group-wide shock wave in Stephan's Quintet. These Spitzer Space Telescope
observations reveal emission lines of molecular hydrogen and little else. this
is the first time an almost pure H_2 line spectrum has been seen in an
extragalactic object. Along with the absence of PAH features and very low
excitation ionized gas tracers, the spectra resemble shocked gas seen in
Galactic supernova remnants, but on a vast scale. The molecular emission
extends over 24 kpc along the X-ray emitting shock-front, but has ten times the
surface luminosity as the soft X-rays, and about one-third the surface
luminosity of the IR continuum. We suggest that the powerful H_2 emission is
generated by the shock wave caused when a high-velocity intruder galaxy
collides with filaments of gas in the galaxy group. Our observations suggest a
close connection between galaxy-scale shock-waves and strong broad H_2 emission
lines, like those seen in the spectra of Ultraluminous Infrared Galaxies where
high-speed collisions between galaxy disks are common.


title:
Probing Multiple Sight Lines through the SN 1006 Remnant by UV
  Absorption Spectroscopy

abstract:
  Absorption-line spectroscopy is an effective probe for cold ejecta within an
SNR, provided that suitable background UV sources can be identified. For the SN
1006 remnant we have identified four such sources, in addition to the
much-studied Schweitzer-Middleditch (SM) star. We have used STIS on HST to
obtain UV spectra of all four sources, to study "core samples" of the SN 1006
interior. The line of sight closest to the center of the SNR shell, passing
only 2.0 arcmin away, is to a V = 19.5 QSO at z = 1.026. Its spectrum shows
broad Fe II absorption lines, asymmetric with red wings broader than blue. The
similarity of these profiles to those seen in the SM star, which is 2.8 arcmin
from the center in the opposite direction, confirms the existence of a bulge on
the far side of SN 1006. The Fe II equivalent widths in the QSO spectrum are ~
50% greater than in the SM star, suggesting that somewhat more iron may be
present within SN 1006 than studies of the SM star alone have indicated, but
this is still far short of what most SNIa models require. The absorption
spectrum against a brighter z = 0.337 QSO seen at 57% of the shell radius shows
broad silicon absorption lines but no iron other than narrow, probably
interstellar lines. The cold iron expanding in this direction must be confined
within v <~ 5200 km/s, also consistent with a high-velocity bulge on the far
side only. The broad silicon lines indicate that the silicon layer has expanded
beyond this point, and that it has probably been heated by a reverse shock.
Finally, the spectra of two ~ A0V stars near the southern shell rim show no
broad or unusually strong absorption lines, suggesting that the low-ionization
ejecta are confined within 83% of the shell radius, at least at the azimuths of
these background sources.


title:
The intensity contrast of solar photospheric faculae and network
  elements II. Evolution over the rising phase of solar cycle 23

abstract:
  We studied the radiative properties of small magnetic elements (active region
faculae and the network) during the rising phase of solar cycle 23 from 1996 to
2001, determining their contrasts as a function of heliocentric angle,
magnetogram signal, and the solar cycle phase. We combined near-simultaneous
full disk images of the line-of-sight magnetic field and photospheric continuum
intensity provided by the MDI instrument on board the SOHO spacecraft. Sorting
the magnetogram signal into different ranges allowed us to distinguish between
the contrast of different magnetic structures. We find that the contrast
center-to-limb variation (CLV) of these small magnetic elements is independent
of time with a 10% precision, when measured during the rising phase of solar
cycle 23. A 2-dimensional empirical expression for the contrast of photospheric
features as a function of both the position on the disk and the averaged
magnetic field strength was determined, showing its validity through the
studied time period. A study of the relationship between magnetogram signal and
the peak contrasts shows that the intrinsic contrast (maximum contrast per unit
of magnetic flux) of network flux tubes is higher than that of active region
faculae during the solar cycle.


title: The 2:1 resonant exoplanetary system orbiting HD73526

abstract:
  We report the detection of a second exoplanet orbiting the G6V dwarf HD73526.
This second planet has an orbital period of 377 d, putting it in a 2:1
resonance with the previously known exoplanet, the orbital period for which is
updated to 188d. Dynamical modeling of the combined system allows solution for
a self-consistent set of orbital elements for both components. HD73526 is the
fourth exoplanetary system (of a total of 18 systems with 2 or more components
currently known) to have components detected in 2:1 resonance. Finding such a
large fraction of multiple planets (more than 20 per cent) in 2:1 resonance
strongly suggests that orbital migration, halted by stabilisation in a trapping
resonance, plays an important role in the evolution of exoplanets in multiple
planet systems.


title:
Luminosity dependent study of the High Mass X-ray Binary Pulsar
  4U~0114+65 with ASCA

abstract:
  Here we report the spectral characteristics of the high and low states of the
pulsar 4U~0114+65 and examine the change in the parameters of the spectral
model. A power law and a photoelectric absorption by material along the line of
sight together with a high energy cut-off suffice to describe the continuum
spectrum in both the states. A fluorescence iron line at $\sim$6.4 keV is
present in the high as well as in the low state, though it is less intense in
the latter. The photon index, cut-off energy and e-folding energy values hardly
show any discernible change over the states. We compare these spectral
characteristics as observed with ASCA to that with other satellites. We also
compare the spectral characteristics of 4U~0114+650 with other X-ray sources
which show intensity variation at different time scales.