title: Spitzer observations of hydrogen deuteride

abstract:
  We report the detection of interstellar hydrogen deuteride (HD) toward the
supernova remnant IC443, and the tentative detection of HD toward the Herbig
Haro objects HH54 and HH7 and the star forming region GGD37 (Cepheus A West).
Our detections are based upon spectral line mapping observations of the R(3)
and R(4) rotational lines of HD, at rest wavelengths of 28.502 and 23.034
micron respectively, obtained using the Infrared Spectrograph onboard the
Spitzer Space Telescope. The HD R(4)/R(3) line intensity ratio promises to be a
valuable probe of the gas pressure in regions where it can be observed. The
derived HD/H2 abundance ratios are 1.19(+0.35/-0.24)E-5, 1.80(+0.54/-0.32)E-5,
and 1.41(+0.46/-0.33)E-5 respectively (68.3% confidence limits, based upon
statistical errors alone) for IC443 (clump C), HH54, and HH7. If HD is the only
significant reservoir of gas-phase deuterium in these sources, the inferred
HD/H2 ratios are all consistent with a gas-phase elemental abundance
[n(D)/n(H)](gas) ~ 7.5E-6, a factor 2 - 3 below the values obtained previously
from observations of atomic deuterium in the local bubble and the Galactic
halo. However, similarly low gas-phase deuterium abundances have been inferred
previously for molecular gas clouds in the Orion region, and in atomic clouds
along sight-lines within the Galactic disk to stars more distant than 500 pc
from the Sun.


title: Dynamical PN Evolution with Magnetic Fields

abstract:
  Hydrodynamical simulations played an important role in understanding the
dynamics and shaping of planetary nebulae in the past century. However,
hydrodynamical simulations were just a first order approach. The new millennium
arrived with the generalized understanding that the effects of magnetic fields
were necessary to study the dynamics of planetary nebulae. Thus, B-fields
introduced a whole new number of physical possibilities for the modeling. In
this paper, we review observational works done in the last 5 years and several
works on magnetohydrodynamics about proto-planetary nebulae, since all the
effort has been focused on that stage, and discuss different scenarios for the
origin of magnetized winds, and the relation binary-bipolararity.


title: A Curious New Milky Way Satellite in Ursa Major

abstract:
  In this Letter, we study a localized stellar overdensity in the constellation
of Ursa Major, first identified in Sloan Digital Sky Survey (SDSS) data and
subsequently followed up with Subaru imaging. Its color-magnitude diagram (CMD)
shows a well-defined sub-giant branch, main sequence and turn-off, from which
we estimate a distance of ~30 kpc and a projected size of ~250 x 125 pc. The
CMD suggests a composite population with some range in metallicity and/or age.
Based on its extent and stellar population, we argue that this is a previously
unknown satellite galaxy of the Milky Way, hereby named Ursa Major II (UMa II)
after its constellation. Using SDSS data, we find an absolute magnitude of M_V
\~ -3.8, which would make it the faintest known satellite galaxy. UMa II's
isophotes are irregular and distorted with evidence for multiple
concentrations; this suggests that the satellite is in the process of
disruption.


title: U solubility in the core of Earth

abstract:
  Uranium is the most important heat producing element in the Earth. The
presence of an appreciable amount of U in the core of Earth would have an
important influence on geodynamics. In this study, the solubility of U in
Fe-10wt% S and in Fe-35wt% S was measured by partitioning experiments with a
mixture of peridotite, uraninite, Fe and FeS powder at pressure (P) of 0-9 GPa
and temperature (T) of 1500-2200 oC. Comparisons with the run products
containing pure Fe as the metal phase in our previous study and re-analysis of
run products were made in this study. We found that in all run products,
including Fe-10wt% S, Fe-35wt% S and pure Fe groups, the solubility and
partitioning of U in the pure metal or metal-sulfide phase relative to the
silicate phase (DU) increases with increasing P and T. With a molten silicate
phase, DU is generally 3-6 times larger than with a solid silicate phase. While
DU has a positive dependence on S concentration of the metal-sulfide phase,
there is a negative correlation between Ca and U. According to our calculations
based on these experimental results, if the core has formed from a magma ocean
at a P of 26 GPa at its base and the core contained 10wt% S, then it could have
incorporated at least 10 ppb U. Alternatively, if the core formed by
percolation and contained 10wt% S, then it could have incorporated 5-22 ppb U.
The geophysical implications of U in the core of Earth are discussed.


title:
The Direct Detection of Lyman-Continuum Emission from Star-forming
  Galaxies at z~3

abstract:
  We present the results of rest-frame ultraviolet spectroscopic observations
of a sample of 14 z~3 star-forming galaxies in the SSA22a field. These spectra
are characterized by unprecedented depth in the Lyman-continuum region. For the
first time, we have detected escaping ionizing radiation from individual
galaxies at high redshift, with two of the 14 objects showing significant
emission below the Lyman limit. We also measured the ratio of emergent flux
density at 1500 AA to that in the Lyman-continuum region, for the individual
detections (C49 and D3) and the sample average. If a correction for the average
IGM opacity is applied to the spectra of the objects C49 and D3, we find
f_1500/f_900,corr(C49)=4.5 and f_1500/f_900,corr(D3)=2.9. The average emergent
flux-density ratio in our sample is <f_1500/f_900,corr>=22, implying an escape
fraction ~4.5 times lower than inferred from the composite spectrum in Steidel
et al. (2001). If this new estimate is representative of LBGs, their
contribution to the metagalactic ionizing radiation field is
J_nu(900)~2.6x10^{-22} erg/s/cm^2/Hz/sr, comparable to the contribution of
optically-selected quasars at the same redshift. The sum of the contributions
from galaxies and quasars is consistent with recent estimates of the level of
the ionizing background at z~3, inferred from the HI Ly-alpha forest optical
depth. There is significant variance among the emergent far-UV spectra in our
sample, yet the factors controlling the detection or non-detection of
Lyman-continuum emission from galaxies are not well-determined. Because we do
not yet understand the source of this variance, significantly larger samples
will be required to obtain robust constraints on the galaxy contribution to the
ionizing background at z~3 and beyond (abridged).


title:
Dynamical friction in constant density cores: a failure of the
  Chandrasekhar formula

abstract:
  Using analytic calculations and N-body simulations we show that in constant
density (harmonic) cores, sinking satellites undergo an initial phase of very
rapid (super-Chandrasekhar) dynamical friction, after which they experience no
dynamical friction at all. For density profiles with a central power law
profile of log-slope, $-\alpha$, the infalling satellite heats the background
and causes $\alpha$ to decrease. For $\alpha < 0.5$ initially, the satellite
generates a small central constant density core and stalls as in the $\alpha =
0$ case.
  We discuss some astrophysical applications of our results to decaying
satellite orbits, galactic bars and mergers of supermassive black hole
binaries. In a companion paper we show that a central constant density core can
provide a natural solution to the timing problem for Fornax's globular
clusters.


title:
Single star progenitors of long gamma-ray bursts I: Model grids and
  redshift dependent GRB rate

abstract:
  We present grids of massive star evolution models at four different
metallicities (Z=0.004, 0.002, 0.001, 0.00001). The effects of rotation on the
stellar structure and the transport of angular momentum and chemical elements
through the Spruit-Tayler dynamo and rotationally induced instabilities are
considered. After discussing uncertainties involved with the adopted physics,
we elaborate the final fate of massive stars as a function of initial mass and
spin rate, at each considered metallicity. In particular, we investigate for
which initial conditions long gamma-ray bursts (GRBs) are expected to be
produced in the frame of the collapsar model. Then, using an empirical spin
distribution of young massive metal-poor stars and a specified
metallicity-dependent history of star-formation, we compute the expected GRB
rate as function of metallicity and redshift based on our stellar evolution
models. The GRB production in our models is limited to metallicities of Z \lsim
0.004, with the consequence that about 50 % of all GRBs are predicted to be
found at redshifts above z = 4, with most supernovae occurring at redshifts
below z\simeq 2.2. The average GRB/SN ratio predicted by our model is about
1/200 globally, and 1/1250 at low redshift. Future strategies for testing the
considered GRB progenitor scenario are briefly discussed.


title:
Numerical Simulations of the Lyman-alpha forest - A comparison of
  Gadget-2 and Enzo

abstract:
  We compare simulations of the Lyman-alpha forest performed with two different
hydrodynamical codes, Gadget-2 and Enzo. A comparison of the dark matter power
spectrum for simulations run with identical initial conditions show differences
of 1-3% at the scales relevant for quantitative studies of the Lyman-alpha
forest. This allows a meaningful comparison of the effect of the different
implementations of the hydrodynamic part of the two codes. Using the same
cooling and heating algorithm in both codes the differences in the temperature
and the density probability distribution function are of the order of 10%.
These differences can be mainly attributed to a slight mismatch in the
resolution. The differences are smaller than or equal to the effects of boxsize
and resolution on these statistics. Once resolution effects are taken into
account the differences in the flux power spectrum - the statistics most widely
used for estimating the matter power spectrum and cosmological parameters from
Lyman-alpha forest data - are about 5%. This is again smaller than or equal to
the effects of boxsize and resolution. Numerical uncertainties due to a
particular implementation of solving the hydrodynamic or gravitational
equations appear therefore to contribute only moderately to the error budget in
estimates of the flux power spectrum from numerical simulations. We further
find that the differences in the flux power spectrum for Enzo simulations run
with and without adaptive mesh refinement are also of order 5% or smaller. The
latter require 10 times less CPU time making the CPU time requirement similar
to that of a version of Gadget-2 that is optimised for Lyman-alpha forest
simulations.


title: Geometrical Distance Determination using Type I X-ray Bursts

abstract:
  With the excellent angular resolution of the Chandra X-ray Observatory, it is
possible to geometrically determine the distance to variable Galactic sources,
based on the phenomenon that scattered radiation appearing in the X-ray halo
has to travel along a slightly longer path than the direct, unscattered
radiation. By measuring the delayed variability, constraints on the source
distance can be obtained if the halo brightness is large enough to dominate the
point spread function (PSF) and to provide sufficient statistics. The distance
to Cyg X-3, which has a quasi-sinusoidal light curve, has been obtained with
this approach by Predehl et al. Here we examine the feasibility of using the
delayed signature of type I X-ray bursts as distance indicators. We use
simulations of delayed X-ray burst light curves in the halo to find that the
optimal annular region and energy band for a distance measurement with a
grating observation is roughly 10-50" and 1-5 keV respectively, assuming
Chandra's effective area and PSF, uniformly distributed dust, the input
spectrum and optical depth to GX 13+1, and the Weingartner & Draine
interstellar grain model. We find that the statistics are dominated by Poisson
noise rather than systematic uncertainties, e.g., the PSF contribution to the
halo. Using Chandra, a distance measurement to such a source at 4 (8) kpc could
be made to about 23% (30%) accuracy with a single burst with 68% confidence. By
stacking many bursts, a reasonable estimate of systematic errors limit the
distance measurement to about 10% accuracy.


title:
Instability of a stalled accretion shock: evidence for the
  advective-acoustic cycle

abstract:
  We analyze the linear stability of a stalled accretion shock in a perfect gas
with a parametrized cooling function L ~ rho^{beta-alpha} P^alpha. The
instability is dominated by the l=1 mode if the shock radius exceeds 2-3 times
the accretor radius, depending on the parameters of the cooling function. The
growth rate and oscillation period are comparable to those observed in the
numerical simulations of Blondin & Mezzacappa (2006). The instability mechanism
is analyzed by separately measuring the efficiencies of the purely acoustic
cycle and the advective-acoustic cycle. These efficiencies are estimated
directly from the eigenspectrum, and also through a WKB analysis in the high
frequency limit. Both methods prove that the advective-acoustic cycle is
unstable, and that the purely acoustic cycle is stable. Extrapolating these
results to low frequency leads us to interpret the dominant mode as an
advective-acoustic instability, different from the purely acoustic
interpretation of Blondin & Mezzacappa (2006). A simplified characterization of
the instability is proposed, based on an advective-acoustic cycle between the
shock and the radius r_nabla where the velocity gradients of the stationary
flow are strongest. The importance of the coupling region in this mechanism
calls for a better understanding of the conditions for an efficient
advective-acoustic coupling in a decelerated, nonadiabatic flow, in order to
extend these results to core-collapse supernovae.


title: Testing Relativity at High Energies Using Spaceborne Detectors

abstract:
  (ABRIDGED) The Gamma-ray Large Area Space Telescope (GLAST) will measure the
spectra of distant extragalactic sources of high energy gamma-rays. GLAST can
look for energy dependent propagation effects from such sources as a signal of
Lorentz invariance violation (LIV). Such sources should also exhibit high
energy spectral cutoffs from pair production interactions with low energy
photons. The properties of such cutoffs can also be used to test LIV. Detectors
to measure gamma-ray polarization can look for the depolarizing effect of
space-time birefingence predicted by loop quantum gravity. A spaceborne
detector array looking down on Earth to study extensive air showers produced by
ultrahigh energy cosmic rays can study their spectral properties and look for a
possible deviation from the predicted GZK effect as another signal of LIV.


title:
Line Strengths in Early-Type Cluster Galaxies at z=0.33: Implications
  for alpha/Fe, Nitrogen and the Histories of E/S0s

abstract:
  [Heavily Abbreviated] In this paper we analyze previously published spectra
with high signal-to-noise ratios of E/S0 galaxies in the rich cluster CL1358+62
at z=0.33, and introduce techniques for fitting stellar population models to
the data. Here we focus on the 19 E and S0 galaxies with an homogeneous set of
eight blue Lick indices. We explore the galaxy properties using six-parameter
stellar population models from the literature, and describe an approach for
fitting the models differentially, such that the largest systematic errors are
avoided. We find: (1) no differences between the stellar population parameters
of Es and S0s, at fixed sigma; (2) the stars in the Es and S0s are uniformly
old, consistent with previously published results using M/L ratios; (3) a
significant correlation of [Z/H] with sigma, in a manner consistent with the
observed B-V colors of the galaxies; (4) no significant correlation of
[alpha/Fe] with sigma; and (5) a significant anti-correlation of [alpha/N] with
[Z/H], which we interpret as the signature of secondary nitrogen. Neither
[alpha/C], nor [alpha/Ca] shows significant variation. While the differences
between our conclusions and the current view of stellar populations may point
to serious deficiencies, our deduced correlation of mean metallicity with sigma
does reproduce the B-V colors of the galaxies, as well as the slope of the
local Mg-sigma relation. In matching the inferred population trends with
published data on nearby galaxies, the line strength-line width relations match
well, save for the narrow iron indices. Taken together, these results reduce
early-type galaxies in clusters to a family with one-parameter, velocity
dispersion, greatly simplifying scenarios for their formation and evolution.


title: Cosmological science enabled by Planck

abstract:
  Planck will be the first mission to map the entire cosmic microwave
background (CMB) sky with mJy sensitivity and resolution better than 10'. The
science enabled by such a mission spans many areas of astrophysics and
cosmology. In particular it will lead to a revolution in our understanding of
primary and secondary CMB anisotropies, the constraints on many key
cosmological parameters will be improved by almost an order of magnitude (to
sub-percent levels) and the shape and amplitude of the mass power spectrum at
high redshift will be tightly constrained.


title:
The Nature of Interstellar Gas toward the Pleiades Revealed in
  Absorption Lines

abstract:
  We present high-resolution, high signal to noise absorption-line observations
of CN, Ca II, Ca I, CH^+, and CH along twenty lines of sight toward members of
the Pleiades. The acquired data enable the most detailed study to date of the
interaction between cluster stars and the surrounding interstellar gas. Total
equivalent widths are consistent with previous investigations except where
weaker features are detected owing to our greater sensitivity. Mean b-values
for the molecular species indicate that toward most of the Pleiades CH is
associated with the production of CH^+ rather than CN. An analysis of radial
velocities reveals a kinematic distinction between ionized atomic gas and
molecular and neutral gas. Molecular components are found with velocities in
the local standard of rest of either ~ +7 km s^-1 or ~ +9.5 km s^-1, with the
higher-velocity components associated with the strongest absorption. Atomic gas
traced by Ca II shows a strong central component at v_LSR ~ +7 km s^-1
exhibiting velocity gradients indicative of cloud-cluster interactions. Gas
density estimates derived from measured CH/CH^+ column density ratios show good
agreement with those inferred from H_2 rotational populations, yielding typical
values of n ~ 50 cm^-3. Our models do not include the important time-dependent
effects on CH^+ formation which may ultimately be needed to extract physical
conditions in these clouds.


title:
Impact of Stellar Dynamics on the Frequency of Giant Planets in Close
  Binaries

abstract:
  Hostile tidal forces may inhibit the formation of Jovian planets in binaries
with semimajor axes of $\la$$50\au$, binaries that might be called ``close'' in
this context. As an alternative to in situ planet formation, a binary can
acquire a giant planet when one of its original members is replaced in a
dynamical interaction with another star that hosts a planet. Simple scaling
relations for the structure and evolution of star clusters, coupled with
analytic arguments regarding binary-single and binary-binary scattering,
indicate that dynamical processes can deposit Jovian planets in $<$1% of close
binaries. If ongoing and future exoplanet surveys measure a much larger
fraction, it may be that giant planets do somehow form frequently in such
systems.


title: Synchrotron flaring in the jet of 3C 279

abstract:
  We study the synchrotron flaring behaviour of the blazar 3C279 based on an
extensive dataset covering 10 years of monitoring at 19 different frequencies
in the radio-to-optical range. The properties of a typical outburst are derived
from the observations by decomposing the 19 lightcurves into a series of
self-similar events. This analysis is achieved by fitting all data
simultaneously to a succession of outbursts defined according to the
shock-in-jet model of Marscher & Gear (1985). We compare the derived properties
of the synchrotron outbursts in 3C279 to those obtained with a similar method
for the quasar 3C273. It is argued that differences in the flaring behaviour of
these two sources are intrinsic to the sources themselves rather than being due
to orientation effects. We also compare the start times and flux densities of
our modelled outbursts with those measured from radio components identified in
Very Long Baseline Interferometry (VLBI) images. We find VLBI counterparts for
most of our model outbursts, although some high-frequency peaking events are
not seen in the radio maps. Finally, we study the link between the appearance
of a new synchrotron component and the EGRET gamma-ray state of the source at
10 different epochs. We find that an early-stage shock component is always
present during high gamma-ray states, while in low gamma-ray states the time
since the onset of the last synchrotron outburst is significantly longer. This
statistically significant correlation supports the idea that gamma-ray flares
are associated with the early stages of shock components propagating in the
jet. We note, however, that the shock wave is already beyond the broad line
region during the gamma-ray flaring.


title: Life Products of Stars

abstract:
  We attempt to document complete energetic transactions of stars in their
life. We calculate photon and neutrino energies that are produced from stars in
their each phase of evolution from 1 to 8 M_sun, using the state-of-the-art
stellar evolution code, tracing the evolution continuously from pre-main
sequence gravitational contraction to white dwarfs. We also catalogue
gravitational and thermal energies and helium, and heavier elements that are
stored in stars and those ejected into interstellar space in each evolutionary
phase.


title: Cosmic variance of weak lensing surveys in the non-Gaussian regime

abstract:
  The results from weak gravitational lensing analyses are subject to a cosmic
variance error term that has previously been estimated assuming Gaussian
statistics. In this letter we address the issue of estimating cosmic variance
errors for weak lensing surveys in the non-Gaussian regime. Using standard cold
dark matter model ray-tracing simulations characterized by Omega_m=0.3,
Omega_Lambda=0.7, h=0.7, sigma_8=1.0 for different survey redshifts z_s, we
determine the variance of the two-point shear correlation function measured
across 64 independent lines of sight. We compare the measured variance to the
variance expected from a random Gaussian field and derive a redshift-dependent
non-Gaussian calibration relation. We find that the ratio can be as high as ~30
for a survey with source redshift z_s ~ 0.5 and ~10 for z_s ~ 1. The transition
scale theta_c above which the ratio is consistent with unity, is found to be
theta_c ~ 20 arcmin for z_s ~ 0.5 and theta_c ~ 10 arcmin for z_s ~ 1. We
provide fitting formula to our results permitting the estimation of
non-Gaussian cosmic variance errors for any weak lensing analysis, and discuss
the impact on current and future surveys. A more extensive set of simulations
will however be required to investigate the dependence of our results on
cosmology, specifically on the amplitude of clustering.


title: Extinction Curves of Lensing Galaxies out to z=1

abstract:
  We present a survey of the extinction properties of ten lensing galaxies, in
the redshift range z = 0.04 - 1.01, using multiply lensed quasars imaged with
the ESO VLT in the optical and near infrared. The multiple images act as
'standard light sources' shining through different parts of the lensing galaxy,
allowing for extinction studies by comparison of pairs of images. We explore
the effects of systematics in the extinction curve analysis, including
extinction along both lines of sight and microlensing, using theoretical
analysis and simulations. In the sample, we see variation in both the amount
and type of extinction. Of the ten systems, seven are consistent with
extinction along at least one line of sight. The mean differential extinction
for the most extinguished image pair for each lens is A(V) = 0.56 +- 0.04,
using Galactic extinction law parametrization. The corresponding mean R_V = 2.8
+- 0.4 is consistent with that of the Milky Way at R_V = 3.1, where R_V =
A(V)/E(B-V). We do not see any strong evidence for evolution of extinction
properties with redshift. Of the ten systems, B1152+199 shows the strongest
extinction signal of A(V) = 2.43 +- 0.09 and is consistent with a Galactic
extinction law with R_V = 2.1 +- 0.1. Given the similar redshift distribution
of SN Ia hosts and lensing galaxies, a large space based study of multiply
imaged quasars would be a useful complement to future dark energy SN Ia
surveys, providing independent constraints on the statistical extinction
properties of galaxies up to z~1.


title:
A survey for nanodiamond features in the 3 micron spectra of Herbig
  Ae/Be stars

abstract:
  We have carried out a survey of 60 Herbig Ae/Be stars in the 3 micron
wavelength region in search for the rare spectral features at 3.43 and 3.53
micron. These features have been attributed to the presence of large, hot,
hydrogen-terminated nanodiamonds. Only two Herbig Ae/Be stars, HD 97048 and
Elias 3-1 are known to display both these features. We have obtained
medium-resolution spectra (R ~2500) with the ESO near-IR instrument ISAAC in
the 3.15-3.65 micron range. In our sample, no new examples of sources with
prominent nanodiamond features in their 3 micron spectra were discovered
(detection rate less than 4%). We report tentative 3.53 micron detections in
V921 Sco (=CD-42.11721), HD 163296 and T CrA. The sources which display the
nanodiamond features are not exceptional in the group of Herbig stars with
respect to disk properties, stellar characteristics, or disk and stellar
activity. Moreover, the nanodiamond sources are very different from each other
in terms of these parameters. We do not find evidence for a recent supernova in
the vicinity of any of the nanodiamond sources. We have analyzed the PAH 3.3
micron feature and the Pfund delta hydrogen emission line, two other spectral
features which occur in the 3 micron wavelength range. We reinforce the
conclusion of previous authors that flared-disk systems display significantly
more PAH emission than self-shadowed-disk sources. The Pf delta line detection
rate is higher in self-shadowed-disk sources than in the flared-disk systems.
We discuss the possible origin and paucity of the (nano)diamond features in
Herbig stars. Different creation mechanisms have been proposed in the
literature, amongst others in-situ and supernova-induced formation. Our data
set is inconclusive in proving or disproving either formation mechanism.


title:
Vector current conservation and neutrino emission from singlet-paired
  baryons in neutron stars

abstract:
  Neutrino emission caused by singlet Cooper pairing of baryons in neutron
stars is recalculated by accurately taking into account for conservation of the
vector weak currents. The neutrino emissivity via the vector weak currents is
found to be several orders of magnitude smaller than that obtained before by
different authors. This makes unimportant the neutrino radiation from singlet
pairing of protons or hyperons.


title: Evidence for variable outflows in the Young Stellar Object V645 Cygni

abstract:
  As part of the Red MSX Source Survey of Massive Young Stellar Objects (MYSOs)
we have conducted multi-wavelength follow up observations of the well-known
object V645 Cygni. We present our data on this object, whose near-infrared
spectrum is exceptional and place these in context with previous observations.
Our observations of V645 Cyg included near/mid infrared imaging observations,
13CO 2-1 line observations and high signal-to-noise velocity resolved
near-infrared spectroscopy. The spectrum shows P-Cygni hydrogen Brackett
emission, consistent with a high velocity stellar wind. A red-shifted emission
component to a number of near-IR emission lines was also uncovered. This is
associated with a similar component in the H alpha line. V645 Cyg is also found
to have variable CO first overtone bandhead emission. The data clearly indicate
that the outflow of V645 Cyg is variable. The unidentified feature in a
previously published optical spectrum is identified with a receding outflow at
2000 km per second. The nature of this feature, which is found in hydrogen and
helium atomic lines and CO molecular lines remains a puzzle.


title: Neutrino emission due to Cooper pairing in neutron stars

abstract:
  Neutrino emission caused by Cooper pairing of baryons in neutron stars is
recalculated by accurately taking into account for conservation of the vector
weak current. The vector current contribution to the neutrino emissivity is
found to be several orders of magnitude smaller than that obtained before by
different authors. Therefore, the neutrino energy losses due to singlet-state
pairing of baryons can in practice be neglected in simulations of neutron star
cooling. This makes negligible the neutrino radiation from pairing of protons
or hyperons. The neutrino radiation from triplet pairing takes place through
axial weak currents. For these states, when the total momentum projection is
$m_{j}=0$, the vanishing of the vector weak current contribution results in the
suppression of the neutrino energy losses by about 25%. The neutrino emissivity
due to triplet pairing with $| m_{j}| =2$ is suppressed by about a factor of 3,
caused by the collective contribution of spin-density fluctuations in the
condensate.


title: Power-laws and Non-Power-laws in Dark Matter Halos

abstract:
  Simulated dark matter profiles are often modelled as a `NFW' density profile
rather than a single power law. Recently, attention has turned to the rather
rigorous power-law behaviour exhibited by the `pseudo phase-space density' of
the dark matter halo, which is defined dimensionally in terms of the local
density and velocity dispersion of the dark matter particles. The non-power-law
behaviour of the density profile is generally taken to exclude simple
scale-free, in-fall models; however the power-law behaviour of the
`pseudo-density' is a counter indication. We argue in this paper that both
behaviours may be at least qualitatively understood in terms of a dynamically
evolving self-similarity, rather than the form for self-similar infall that is
fixed by cosmological initial conditions. The evolution is likely due to
collective relaxation such as that provided by the radial-orbit instability on
large scales. We deduce, from a distribution function given by first order
coarse-graining, both the NFW-type density profile and the power-law
pseudo-density profile. The results are not greatly sensitive to variation
about 3 in the power of the velocity dispersion used in the definition of the
phase space pseudo-density. We suggest that the power 2 may create the more
physical quantity, whose deviations from a power-law are a diagnostic of
incomplete relaxation.


title:
Harmonic QPOs and Thick Accretion Disk Oscillations in BL Lac Object AO
  0235+164

abstract:
  Periodic outbursts are observed in many AGNs and usually explained with a
supermassive black hole binary (SMBHB) scenario. However, multiple periods are
observed in some AGNs and cannot be explained with it. Here we analyze the
periodicity of the radio light curves of AO 0235+164 at multi-frequencies and
report the discovery of six QPOs in integer ratio 1:2:3:4:5:6 of QPO
frequencies, of which the second with period $P_2 = (5.46 \pm 0.47) {\rm yr}$
is the strongest. We fit the radio light curves and show that the initial
phases of six QPOs have zero or $\pi$ differences relative to each other. We
suggest a harmonic relationship of QPOs. The centroid frequency, relative
strength, harmonic relationship and relative initial phases of QPOs are
independent of radio frequency. The harmonic QPOs are likely due to the
quasi-periodic injection of plasma from an oscillating accretion disk into the
jet. We estimate the supermassive black hole mass $M_{\rm BH} \simeq (4.72\pm
2.04) \times 10^8 M_\odot$ and the accretion rate $\dot{m}\simeq 0.007$. With
the knowledge of accretion disk, it implies that the inner region of accretion
disk of AO 0235+164 is a radiatively inefficient accretion flow. The
oscillation accretion is due to the p-mode oscillation of the thick disk
probably excited by a SMBHB. The theoretical predications of fundamental
oscillation frequency and the harmonics are well consistent with the
observations. Harmonic QPOs would be absent when the thick disk becomes
geometrically thin due to the increase of accretion rate. We discuss the
observations of AO 0235+164 basing on the SMBHB-thick disk oscillation
scenario.


title: XMM-Newton observation of the eclipsing binary Algol

abstract:
  We present an {\sl XMM-Newton} observation of the eclipsing binary Algol
which contains an X-ray dark B8V primary and an X-ray bright K2IV secondary.
The observation covered the optical secondary eclipse and captured an X-ray
flare that was eclipsed by the B star. The EPIC and RGS spectra of Algol in its
quiescent state are described by a two-temperature plasma model. The cool
component has a temperature around 6.4$\times 10^{6}$ K while that of the hot
component ranges from 2 to 4.0$\times 10^{7}$ K. Coronal abundances of C, N, O,
Ne, Mg, Si and Fe were obtained for each component for both the quiescent and
the flare phases, with generally upper limits for S and Ar, and C, N, and O for
the hot component. F-tests show that the abundances need not to be different
between the cool and the hot component and between the quiescent and the flare
phase with the exception of Fe. Whereas the Fe abundance of the cool component
remains constant at $\sim$0.14, the hot component shows an Fe abundance of
$\sim$0.28, which increases to $\sim$0.44 during the flare. This increase is
expected from the chromospheric evaporation model. The absorbing column density
$N_H$ of the quiescent emission is 2.5$\times10^{20}$ cm$^{-2}$, while that of
the flare-only emission is significantly lower and consistent with the column
density of the interstellar medium. This observation substantiates earlier
suggestions of the presence of X-ray absorbing material in the Algol system.


title: A fresh look on the heating mechanisms of the Solar corona

abstract:
  Recently using Particle-In-Cell simulations i.e. in the kinetic plasma
description Tsiklauri et al. and G\'enot et al. reported on a discovery of a
new mechanism of parallel electric field generation, which results in electron
acceleration. In this work we show that the parallel (to the uniform
unperturbed magnetic field) electric field generation can be obtained in much
simpler framework using ideal Magnetohydrodynamic (MHD) description, i.e.
without resorting to complicated wave particle interaction effects such as ion
polarisation drift and resulting space charge separation which seems to be an
ultimate cause of the electron acceleration. Further, in the context of the
coronal heating problem a new {\it two stage mechanism} of the plasma heating
is presented by putting emphasis, first, on the generation of parallel electric
fields within {\it ideal MHD} description directly, rather than focusing on the
enhanced dissipation mechanisms of the Alfv\'en waves and, second, dissipation
of these parallel electric fields via {\it kinetic} effects. It is shown that a
single Alfv\'en wave harmonic with frequency ($\nu = 7$ Hz), (which has
longitudinal wavelength $\lambda_A = 0.63$ Mm for putative Alfv\'en speed of
4328 km s$^{-1}$) the generated parallel electric field could account for the
10% of the necessary coronal heating requirement. We conjecture that wide
spectrum (10$^{-4}-10^3$ Hz) Alfv\'en waves, based on observationally
constrained spectrum, could provide necessary coronal heating requirement.


title:
MHD versus kinetic effects in the solar coronal heating: a two stage
  mechanism

abstract:
  Using Particle-In-Cell simulations i.e. in the kinetic plasma description the
discovery of a new mechanism of parallel electric field generation was recently
reported. Here we show that the electric field generation parallel to the
uniform unperturbed magnetic field can be obtained in a much simpler framework
using the ideal magnetohydrodynamics (MHD) description. In ideal MHD the
electric field parallel to the uniform unperturbed magnetic field appears due
to fast magnetosonic waves which are generated by the interaction of weakly
non-linear Alfv\'en waves with the transverse density inhomogeneity. In the
context of the coronal heating problem a new {\it two stage mechanism} of
plasma heating is presented by putting emphasis, first, on the generation of
parallel electric fields within an {\it ideal MHD} description directly, rather
than focusing on the enhanced dissipation mechanisms of the Alfv\'en waves and,
second, dissipation of these parallel electric fields via {\it kinetic}
effects. It is shown that for a single Alfv\'en wave harmonic with frequency
$\nu = 7$ Hz, and longitudinal wavelength $\lambda_A = 0.63$ Mm for a putative
Alfv\'en speed of 4328 km s$^{-1}$, the generated parallel electric field could
account for 10% of the necessary coronal heating requirement. We conjecture
that wide spectrum (10$^{-4}-10^3$ Hz) Alfv\'en waves, based on the
observationally constrained spectrum, could provide the necessary coronal
heating requirement. By comparing MHD versus kinetic results we also show that
there is a clear indication of the {\it anomalous resistivity} which is 100s of
times greater than the classical Braginskii value.


title:
The jet/disk connection in AGN: Chandra and XMM observations of three
  powerful radio-loud quasars

abstract:
  The connection between the accretion process that powers AGN and the
formation of jets is still poorly understood. Here we tackle this issue using
new, deep \chandra and \xmm observations of the cores of three powerful radio
loud quasars: 1136--135, 1150+497 (\chandra), and 0723+679 (\xmm), in the
redshift range $z$=0.3--0.8. These sources are known from our previous \chandra
snapshot survey to have kpc-scale X-ray jets. In 1136--135 and 1150+497,
evidence is found for the presence of diffuse thermal X-ray emission around the
cores, on scales of 40--50 kpc and with luminosity L$_{0.3-2 keV} \sim 10^{43}$
\lum, suggesting thermal emission from the host galaxy or a galaxy group. The
X-ray continua of the cores in the three sources are described by an
upward-curved (concave) broken power law, with photon indices $\Gamma_{soft}
\sim 1.8-2.1$ and $\Gamma_{hard} \sim 1.7$ below and above $\approx 2$ keV,
respectively. There is evidence for an unresolved \feka line with EW $\sim$ 70
eV in the three quasars. The Spectral Energy Distributions of the sources can
be well described by a mix of jet and disk emission, with the jet dominating
the radio and hard X-rays (via synchrotron and external Compton) and the disk
dominating the optical/UV through soft X-rays. The ratio of the jet-to-disk
powers is $\sim 1$, consistent with those derived for a number of gamma-ray
emitting blazars. This indicates that near equality of accretion and jet power
may be common in powerful radio-loud AGN.


title: Stokes Theorem and the Equations of GRMHD

abstract:
  This paper provides an alternate derivation of the equations used in the
GRMHD code of De Villiers and Hawley using Stokes Theorem. This derivation
places the published form of the discretized equations of GRMHD in a broader
context, and suggests possible future directions for numerical work.


title:
A mechanism for parallel electric field generation in the MHD limit:
  possible implications for the coronal heating problem in the two stage
  mechanism

abstract:
  We solve numerically ideal, 2.5D, MHD equations in Cartesian coordinates,
with a plasma beta of 0.0001 starting from the equilibrium that mimics a
footpoint of a large curvature radius solar coronal loop or a polar region
plume. On top of such an equilibrium, a purely Alfv\'enic, linearly polarised,
plane wave is launched. In the context of the coronal heating problem a new two
stage mechanism of plasma heating is presented by putting emphasis, first, on
the generation of parallel electric fields within an ideal MHD description
directly, rather than focusing on the enhanced dissipation mechanisms of the
Alfv\'en waves and, second, dissipation of these parallel electric fields via
{\it kinetic} effects. It is shown that a single Alfv\'en wave harmonic with
frequency $\nu = 7$ Hz and longitudinal wavelength $\lambda_A = 0.63$ Mm, for a
putative Alfv\'en speed of 4328 km s$^{-1}$, the generated parallel electric
field could account for 10% of the necessary coronal heating requirement. We
conjecture that wide spectrum (10$^{-4}-10^3$ Hz) Alfv\'en waves, based on the
observationally constrained spectrum, could provide the necessary coronal
heating requirement. The exact amount of energy that could be deposited by such
waves through our mechanism of parallel electric field generation can only be
calculated once a more complete parametric study is done. Thus, the
"theoretical spectrum" of the energy stored in parallel electric fields versus
frequency needs to be obtained.


title:
On the luminosity-redshift relation in brane-worlds with cosmological
  constant

abstract:
  In this paper we calculate the luminosity distance - redshift relation for a
special type of flat Friedmann brane with cosmological constant. This special
case is singled out by its simplicity, the luminosity distance being given in
terms of elementary functions. We compare our analytical result with the
expresssion of the luminosity distance for the flat
Friedmann-Lemaitre-Robertson-Walker (FLRW) universe and discuss the
differences.


title: Astrophysics in 2005

abstract:
  We bring you, as usual, the Sun and Moon and stars, plus some galaxies and a
new section on astrobiology. Some highlights are short (the newly identified
class of gamma-ray bursts, and the Deep Impact on Comet 9P/ Tempel 1), some
long (the age of the universe, which will be found to have the Earth at its
center), and a few metonymic, for instance the term "down-sizing" to describe
the evolution of star formation rates with redshift.


title:
The answer is blowing in the wind: Simulating the interaction of jets
  with dynamic cluster atmospheres

abstract:
  We present numerical simulations investigating the interaction of AGN jets
with galaxy clusters, for the first time taking into account the dynamic nature
of the cluster gas and detailed cluster physics. The simulations successfully
reproduce the observed morphologies of radio sources in clusters. We find that
cluster inhomogeneities and large scale flows have significant impact on the
morphology of the radio source and cannot be ignored a-priori when
investigating radio source dynamics. Morphological comparison suggests that the
gas in the centres of clusters like Virgo and Abell 4059 shows significant
shear and/or rotation. We find that shear and rotation in the intra-cluster
medium move large amounts of cold material back into the path of the jet,
ensuring that subsequent jet outbursts encounter a sufficient column density of
gas to couple with the inner cluster gas, thus alleviating the problem of
evacuated channels discussed in the recent literature. The same effects
redistribute the excess energy Delta_E deposited by the jets, making the
distribution of Delta_E at late times consistent with being isotropic.


title: The Starburst Contribution to the Extra-Galactic Gamma-Ray Background

abstract:
  Cosmic ray protons interacting with gas at the mean density of the
interstellar medium in starburst galaxies lose energy rapidly via inelastic
collisions with ambient nuclei. The resulting pions produce secondary electrons
and positrons, high-energy neutrinos, and gamma-ray photons. We estimate the
cumulative gamma-ray emission from starburst galaxies. We find a total
integrated background above 100 MeV of F_gamma ~ 10^{-6} GeV/cm^2/s/sr and a
corresponding specific intensity at GeV energies of nuI_nu ~ 10^{-7}
GeV/cm^2/s/sr. Starbursts may thus account for a significant fraction of the
extra-galactic $\gamma$-ray background. We show that the FIR-radio correlation
provides a strong constraint on the gamma-ray emission from starburst galaxies
because pions decay into both gamma-rays and radio-emitting electron/positron
pairs. We identify several nearby systems where the potential for observing
gamma-ray emission is the most favorable (M82, NGC 253, and IC 342), predict
their fluxes, and predict a linear FIR-gamma-ray correlation for the densest
starbursts. If established, the FIR-gamma-ray correlation would provide strong
evidence for the ``calorimeter'' theory of the FIR-radio correlation and would
imply that cosmic rays in starburst galaxies interact with gas at approximately
the mean density of the interstellar medium (ISM), thereby providing an
important constraint on the physics of the ISM in starbursts.


title: Spitzer Observations of two TW Hydrae Association Brown Dwarfs

abstract:
  We present Spitzer Space Telescope observations of two TW Hydrae Association
brown dwarfs, 2MASSW J1207334-393254 and 2MASSW J1139511-315921, in the IRAC
and MIPS 24 micron bands. Based on their IRAC colors, we have classified them
as Classical and Weak-line T Tauri stars, respectively. For 2MASSW
J1207334-393254, we have found that a flat disk model fits the data very well.
This brown dwarf shows the presence of warm (T > 100 K) circumstellar dust
close (R < 0.2 AU) to it, and does not display any signs of cleansing of dust
within several AU of the star. In comparison with other TWA members that show
excess in IR, we suggest that there exists a different disk evolution/dust
processing mechanism for stellar and sub-stellar objects. 2MASSW
J1139511-315921 does not show any significant excess in any of the IRAC bands,
but a small one at 24 micron, which is not significant enough to suggest the
presence of warm dust around this star. It shows signs of dust cleansing in the
inner several AU, similar to most of the other TWA members.


title:
Gemini/GMOS IFU stellar kinematics of the nuclear region of six nearby
  active galaxies

abstract:
  We present two-dimensional (2D) mapping of the stellar velocity field within
the inner 5 arcsec of six nearby active galaxies, using spectra obtained with
the Integral Field Unit of the GMOS instrument at the Gemini North telescope.
The spatial resolution range from 20 to about 180 pc, and the observed field of
view covers a few hundred parsecs around the nuclei. The Calcium II triplet
absorption features at ~ 8500 A were used to measure the stellar radial
velocities and velocity dispersions (sigma). A simple kinematical model
assuming a purely rotating system with circular orbits in a plane was fitted to
the radial velocity data. The turnover of the rotation curve is at only ~ 50 pc
for NGC 4051 and between 200 and 700 pc for the other 5 galaxies. The sigma
maps show the largest values at the centre. In the cases of NGC 2273 and NGC
3227, there is a decrease to sigma ~ 70-80 km/s at ~ 200-300 pc from the
nucleus, delineating partial rings of low sigma values. A similar broken ring
seems to be present at ~ 400 pc from the nucleus also in NGC 4593. We interpret
these low sigma rings as traces of recently formed stars that partially keep
the cold kinematics of the original gas from which they have formed.
  The main novelty of the present work is the unprecedented spatial resolution
reached by a 2D study of stellar kinematics of Seyfert galaxies using an IFU.
The few similar IFU studies available in the literature for Seyfert galaxies
have a much poorer spatial resolution and/or are restricted to the study of
emission line kinematics.


title: Dufour and Soret effects in a magnetized and non-magnetized plasma

abstract:
  It is well known that magnetic fields affect heat conduction in a different
way in the direction parallel and perpendicular to the field. In this paper a
formal derivation of this phenomenon and analytical expressions for the
transport coefficients based in the Boltzmann equation are presented. Moreover,
the Dufour effect or diffusion thermo effect is usually ignored in plasma
transport theory. In this work, analytic expressions for the parallel and
perpendicular thermal conductivities as well as the coefficients for both the
thermal diffusion, or Soret, effect and the Dufour effect are formally derived.
It is also shown how the heat conduction in the perpendicular direction
decreases with increasing magnetic field and how in both directions the
diffusion thermo effect is significant compared to thermal conduction. Other
aspects of this work are also emphasized.


title:
Formation and Evolution of Planetary Systems: Upper Limits to the Gas
  Mass in Disks Around Sun-like Stars

abstract:
  We have carried out a sensitive search for gas emission lines at infrared and
millimeter wavelengths for a sample of 15 young sun-like stars selected from
our dust disk survey with the Spitzer Space Telescope. We have used
mid-infrared lines to trace the warm (300-100 K) gas in the inner disk and
millimeter transitions of 12CO to probe the cold (~20 K) outer disk. We report
no gas line detections from our sample. Line flux upper limits are first
converted to warm and cold gas mass limits using simple approximations allowing
a direct comparison with values from the literature. We also present results
from more sophisticated models following Gorti and Hollenbach (2004) which
confirm and extend our simple analysis. These models show that the SI line at
25.23 micron can set constraining limits on the gas surface density at the disk
inner radius and traces disk regions up to a few AU. We find that none of the
15 systems have more than 0.04 MJ of gas within a few AU from the disk inner
radius for disk radii from 1 AU up to ~40 AU. These gas mass upper limits even
in the 8 systems younger than ~30 Myr suggest that most of the gas is dispersed
early. The gas mass upper limits in the 10-40 AU region, that is mainly traced
by our CO data, are <2 Mearth. If these systems are analogs of the Solar
System, either they have already formed Uranus- and Neptune-like planets or
they will not form them beyond 100 Myr. Finally, the gas surface density upper
limits at 1 AU are smaller than 0.01% of the minimum mass solar nebula for most
of the sources. If terrestrial planets form frequently and their orbits are
circularized by gas, then circularization occurs early.


title: 2MASS wide field extinction maps - I. The Pipe nebula

abstract:
  We present a 8 deg x 6 deg, high resolution extinction map of the Pipe nebula
using 4.5 million stars from the Two Micron All Sky Survey (2MASS) point source
catalog. The use of NICER, a robust and optimal technique to map the dust
column density, allows us to detect a Av = 0.5 mag extinction at a 3-sigma
level with a 1 arcmin resolution. We find for the Pipe nebula a normal
reddening law, E(J-H) = (1.85 +/- 0.15) E(H-K). We measure the cloud distance
using Hipparchos and Tycho parallaxes, and obtain ~130 pc. This, together with
the total estimated mass, 10^4 Msun, makes the Pipe the closest massive cloud
complex to Earth. We compare the NICER extinction map to the NANTEN 12CO
observations and derive with unprecedented accuracy the relationship between
the near-infrared extinction and the 12CO column density and hence (indirectly)
the 12CO X-factor, that we estimate to be 2.91 10^20 cm^-2 K^-1 km^-1 s in the
range Av <- [0.9, 5.4] mag. We identify ~1500 OH/IR stars located within the
Galactic bulge in the direction of the Pipe field. This represents a
significant increase of the known numbers of such stars in the Galaxy. Our
analysis confirms the power and simplicity of the color excess technique to
study molecular clouds. The comparison with the NANTEN 12CO data corroborates
the insensitivity of CO observations to low column densities (up to
approximately 2 mag in Av), and shows also an irreducible uncertainty in the
dust-CO correlation of about 1 mag of visual extinction.


title:
Outgassing of Ordinary Chondritic Material and Some of its Implications
  for the Chemistry of Asteroids, Planets, and Satellites

abstract:
  We used chemical equilibrium calculations to model thermal outgassing of
ordinary chondritic material as a function of temperature, pressure, and bulk
compositions and use our results to discuss outgassing on asteroids and the
early Earth. The calculations include ~1,000 solids and gases of the elements
Al, C, Ca, Cl, Co, Cr, F, Fe, H, K, Mg, Mn, N, Na, Ni, O, P, S, Si, and Ti. The
major outgassed volatiles from ordinary chondritic material are CH4, H2, H2O,
N2, and NH3(the latter at conditions where hydrous minerals form). Contrary to
widely held assumptions, CO is never the major C-bearing gas during ordinary
chondrite metamorphism. The calculated oxygen fugacity (partial pressure) of
ordinary chondritic material is close to that of the quartz-fayalite-iron (QFI)
buffer. Our results are insensitive to variable total pressure, variable
volatile element abundances, and kinetic inhibition of C and N dissolution in
Fe metal. Our results predict that Earth's early atmosphere contained CH4, H2,
H2O, N2, and NH3; similar to that used in Miller-Urey synthesis of organic
compounds.


title: Looking at the Fundamental Plane through a gravitational lens

abstract:
  We consider the Fundamental Plane of elliptical galaxies lensed by the
gravitational field of a massive deflector (typically, a cluster of galaxies).
We show that the Fundamental Plane relation provides a straightforward
measurement of the projected mass distribution of the lens with a typical
accuracy of ~0.15 in the dimensionless column density kappa. The proposed
technique breaks the mass-sheet degeneracy completely and is thus expected to
serve as an important complement to other lensing-based analyses. Moreover, its
ability to measure directly the mass distribution on the small pencil beams
that characterize the size of background galaxies may lead to crucial tests for
current scenarios of structure formation.


title:
They Came From the Deep in the Supernova: The Origin of TiC and Metal
  Subgrains in Presolar Graphite Grains

abstract:
  A new formation scenario for TiC and Fe,Ni-metal inclusions in presolar
graphite grains of supernova origin is described. The mineralogy and chemistry
require condensation of (Fe,Ni)-titanides from Fe, Ni, and Ti-rich gaseous
ejecta, subsequent carburization to make TiC and metal, and encapsulation into
graphite. Titanides only condense if Si is depleted relative to heavier mass
elements, which requires alpha-rich freeze-out and a deep mass-cut for the
supernova ejecta. This Si-poor core material must remain unmixed with other
supernova zones until the titanides condensed. This can be accomplished by
transport of core ejecta in bipolar jets through the major expanding supernova
zone ejecta. If the jets stall in regions dominated by C-rich ejecta such as
C-He zone where graphite condenses, thermochemically favored in situ
carburization of the titanides - either before or during encapsulation into
condensing graphite - leads to a TiC and metal composite. This scenario agrees
with theoretical models and observations of asymmetric core collapse in
supernovae that are associated with bipolar jets loaded with iron-peak
elements.


title: Physics of Strongly Magnetized Neutron Stars

abstract:
  There has recently been growing evidence for the existence of neutron stars
possessing magnetic fields with strengths that exceed the quantum critical
field strength of $4.4 \times 10^{13}$ G, at which the cyclotron energy equals
the electron rest mass. Such evidence has been provided by new discoveries of
radio pulsars having very high spin-down rates and by observations of bursting
gamma-ray sources termed magnetars. This article will discuss the exotic
physics of this high-field regime, where a new array of processes becomes
possible and even dominant, and where familiar processes acquire unusual
properties. We review the physical processes that are important in neutron star
interiors and magnetospheres, including the behavior of free particles, atoms,
molecules, plasma and condensed matter in strong magnetic fields, photon
propagation in magnetized plasmas, free-particle radiative processes, the
physics of neutron star interiors, and field evolution and decay mechanisms.
Application of such processes in astrophysical source models, including
rotation-powered pulsars, soft gamma-ray repeaters, anomalous X-ray pulsars and
accreting X-ray pulsars will also be discussed. Throughout this review, we will
highlight the observational signatures of high magnetic field processes, as
well as the theoretical issues that remain to be understood.


title:
Constraints on the Accretion History of Massive Black Holes from Faint
  X-ray Counts

abstract:
  We investigate how hierarchical models for the co-evolution of the massive
black hole (MBH) and AGN population can reproduce the observed faint X-ray
counts. We find that the main variable influencing the theoretical predictions
is the Eddington ratio of accreting sources. We compare three different models
proposed for the evolution of AGN Eddington ratio, f_Edd: constant f_Edd=1,
f_Edd decreasing with redshift, and f_Edd depending on the AGN luminosity, as
suggested by simulations of galactic mergers including BHs and AGN feedback. We
follow the full assembly of MBHs and host halos from early times to the present
in a LambdaCDM cosmology. AGN activity is triggered by halo major mergers and
MBHs accrete mass until they satisfy the observed correlation with velocity
dispersion. We find that all three models can reproduce fairly well the total
faint X-ray counts. The redshift distribution is however poorly matched in the
first two models. The Eddington ratios suggested by merger simulations predicts
no turn-off of the faint end of the AGN optical luminosity function at
redshifts z>=1 down to very low luminosity.


title: Spitzer 70-micron Source Counts in GOODS-North

abstract:
  We present ultra-deep Spitzer 70-micron observations of GOODS-North. For the
first time, the turn-over in the 70-micron Euclidean-normalized differential
source counts is observed. We derive source counts down to a flux density of
1.2mJy. From the measured source counts and fluctuation analysis, we estimate a
power-law approximation of the faint 70-micron source counts of dN/dS
proportional to S^{-1.6}, consistent with that observed for the faint 24-micron
sources. An extrapolation of the 70-micron source counts to zero flux density
implies a total extragalactic background light (EBL) of 7.4+/-1.9 nW m^{-2}
sr^{-1}. The source counts above 1.2mJy account for about 60% of the estimated
EBL. From fluctuation analysis, we derive a photometric confusion level of
sigma_c = 0.30+/-0.15 mJy (q=5) for the Spitzer 70-micron band.


title:
Distinguishing Propagation vs. Launch Physics of Astrophysical Jets and
  the Role of Experiments

abstract:
  The absence of other viable momentum sources for collimated flows leads to
the likelihood that magnetic fields play a fundamental role in jet launch
and/or collimation in astrophysical jets. To best understand the physics of
jets, it is useful to distinguish between the launch region where the jet is
accelerated and the larger scales where the jet propagates as a collimated
structure. Observations presently resolve jet propagation, but not the launch
region. Simulations typically probe the launch and propagation regions
separately, but not both together. Here, I identify some of the physics of jet
launch vs. propagation and what laboratory jet experiments to date have probed.
Reproducing an astrophysical jet in the lab is unrealistic, so maximizing the
benefit of the experiments requires clarifying the astrophysical connection.


title:
Accretion onto Supermassive Black Holes in Quasars: Learning from
  Optical/UV Observations

abstract:
  Accretion processes in quasars and active galactic nuclei are still poorly
understood, especially as far as the connection between observed spectral
properties and physical parameters is concerned. Quasars show an additional
degree of complexity compared to stars that is related to anisotropic
emission/obscuration influencing the observed properties in most spectral
ranges. This complicating factor has hampered efforts to define the equivalent
of an Hertzsprung-Russel diagram for quasars. Even if it has recently become
possible to estimate black hole mass and Eddington ratio for sources using
optical and UV broad emission lines, the results are still plagued by large
uncertainties. Nevertheless, robust trends are emerging from multivariate
analysis of large spectral datasets of quasars. A firm observational basis is
being laid out by accurate measurements of broad emission line properties
especially when the source rest-frame is known. We consider the most widely
discussed correlations (i.e. the so-called "eigenvector 1 parameter space" and
the "Baldwin effect") and analyze how they can be explained in terms of
accretion properties, broad line region structure, and source evolution. We
critically review recent estimates of black hole mass, accretion rate, spin and
possible orientation indicators, stressing that any improvement in these
parameters will provide a much better understanding of the physics and dynamics
of the region producing the optical and UV broad emission lines. More accurate
measurements of Eddington ratio and black hole mass may have a significant
impact on our ideas about evolution of quasar properties with redshift and
luminosity as well as on broader cosmological issues.


title: Influence of protons on the capture of electrons by 7Be in the Sun

abstract:
  The capture of electrons by the nucleus $^{7}Be$ from the three-body initial
state $p+e^{-}+^{7}Be$ in the continuum is studied. On the basis of the
expansion of the three-body continuum wave function in the small parameter
$\epsilon\approx ({m_e}/{m_p})^{1/2}$ [$m_e$ ($m_p$) is the electron (proton)
mass], the role of the protons on the electron capture is considered. The
results are compared with the traditional treatment of the electron capture by
the nucleus $^{7}Be$. For stars with the density and temperature like in the
centre of the Sun the studied mechanism can make non-negligible contribution to
the capture rate.


title:
Line-of-sight velocity dispersions and a mass distribution model of the
  Sa galaxy NGC 4594

abstract:
  In the present paper we develop an algorithm allowing to calculate
line-of-sight velocity dispersions in an axisymmetric galaxy outside of the
galactic plane. When constructing a self-consistent model, we take into account
the galactic surface brightness distribution, stellar rotation curve and
velocity dispersions. This algorithm is applied to a Sa galaxy NGC 4594 = M
104, for which there exist velocity dispersion measurements outside of the
galactic major axis. The mass distribution model is constructed in two stages.
In the first stage we construct a luminosity distribution model, where only
galactic surface brightness distribution is taken into account. Thereafter, in
the second stage we develop on the basis of the Jeans equations a detailed mass
distribution model and calculate line-of-sight velocity dispersions and the
stellar rotation curve. Here a dark matter halo is added to visible components.
Calculated dispersions are compared with observations along different slit
positions perpendicular and parallel to the galactic major axis. In the
best-fitting model velocity dispersion ellipsoids are radially elongated.
Outside the galactic plane velocity dispersion behaviour is more sensitive to
the dark matter density distribution and allows to estimate dark halo
parameters.


title: New algorithms for adaptive optics point-spread function reconstruction

abstract:
  Context. The knowledge of the point-spread function compensated by adaptive
optics is of prime importance in several image restoration techniques such as
deconvolution and astrometric/photometric algorithms. Wavefront-related data
from the adaptive optics real-time computer can be used to accurately estimate
the point-spread function in adaptive optics observations. The only
point-spread function reconstruction algorithm implemented on astronomical
adaptive optics system makes use of particular functions, named $U\_{ij}$.
These $U\_{ij}$ functions are derived from the mirror modes, and their number
is proportional to the square number of these mirror modes. Aims. We present
here two new algorithms for point-spread function reconstruction that aim at
suppressing the use of these $U\_{ij}$ functions to avoid the storage of a
large amount of data and to shorten the computation time of this PSF
reconstruction. Methods. Both algorithms take advantage of the eigen
decomposition of the residual parallel phase covariance matrix. In the first
algorithm, the use of a basis in which the latter matrix is diagonal reduces
the number of $U\_{ij}$ functions to the number of mirror modes. In the second
algorithm, this eigen decomposition is used to compute phase screens that
follow the same statistics as the residual parallel phase covariance matrix,
and thus suppress the need for these $U\_{ij}$ functions. Results. Our
algorithms dramatically reduce the number of $U\_{ij}$ functions to be computed
for the point-spread function reconstruction. Adaptive optics simulations show
the good accuracy of both algorithms to reconstruct the point-spread function.


title: Mass Accretion onto T Tauri Stars

abstract:
  It is now accepted that accretion onto classical T Tauri stars is controlled
by the stellar magnetosphere, yet to date most accretion models have assumed
that their magnetic fields are dipolar. By considering a simple steady state
accretion model with both dipolar and complex magnetic fields we find a
correlation between mass accretion rate and stellar mass of the form $\dot{M}
\propto M_{\ast}^{\alpha}$, with our results consistent within observed
scatter. For any particular stellar mass there can be several orders of
magnitude difference in the mass accretion rate, with accretion filling factors
of a few percent. We demonstrate that the field geometry has a significant
effect in controlling the location and distribution of hot spots, formed on the
stellar surface from the high velocity impact of accreting material. We find
that hot spots are often at mid to low latitudes, in contrast to what is
expected for accretion to dipolar fields, and that particularly for higher mass
stars, the accretion flow is predominantly carried by open field lines.


title: How to calculate the CMB spectrum

abstract:
  We present a self-contained description of everything needed to write a
program that calculates the CMB power spectrum for the standard model of
cosmology (LCDM). This includes the equations used, assumptions and
approximations imposed on their solutions, and most importantly the algorithms
and programming tricks needed to make the code actually work. The resulting
program is compared to CMBFAST and typically agrees to within 0.1% - 0.4%. It
includes both helium, reionization, neutrinos and the polarization power
spectrum. The methods presented here could serve as a starting point for people
wanting to write their own CMB program from scratch, for instance to look at
more exotic cosmological models where CMBFAST or the other standard programs
can't be used directly.


title:
Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI
  spectroscopy of HD104237

abstract:
  We investigate the origin of the $\mathrm{Br}\gamma$ emission of the Herbig
Ae star HD104237 on Astronomical Unit (AU) scales. Using AMBER/VLTI at a
spectral resolution R=1500 spatially resolve the emission in both the BrGamma
line and the adjacent continuum. The visibility does not vary between the
continuum and the BrGamma line, even though the line is strongly detected in
the spectrum, with a peak intensity 35% above the continuum. This demonstrates
that the line and continuum emission have similar size scales. We assume that
the K-band continuum excess originates in a ``puffed-up'' inner rim of the
circumstellar disk, and discuss the likely origin of BrGamma. We conclude that
this emission most likely arises from a compact disk wind, launched from a
region 0.2-0.5 AU from the star, with a spatial extent similar to that of the
near infrared continuum emission region, i.e, very close to the inner rim
location.


title: Constraining Isocurvature Initial Conditions with WMAP 3-year data

abstract:
  We present constraints on the presence of isocurvature modes from the
temperature and polarization CMB spectrum data from the WMAP satellite alone,
and in combination with other datasets including SDSS galaxy survey and SNLS
supernovae. We find that the inclusion of polarization data allows the WMAP
data alone, as well as in combination with complementary observations, to place
improved limits on the contribution of CDM and neutrino density isocurvature
components individually. With general correlations, the upper limits on these
sub-dominant isocurvature components are reduced to ~60% of the first year WMAP
results, with specific limits depending on the type of fluctuations. If
multiple isocurvature components are allowed, however, we find that the data
still allow a majority of the initial power to come from isocurvature modes. As
well as providing general constraints we also consider their interpretation in
light of specific theoretical models like the curvaton and double inflation.


title: A Search for Fallback Disks in Four Young Supernova Remnants

abstract:
  We report on our search for the optical/infrared counterparts to the central
compact objects in four young supernova remnants: Pup A, PKS 1209-52, RCW 103,
and Cas A. The X-ray point sources in these supernova remnants are excellent
targets for probing the existence of supernova fallback disks, since
irradiation of a disk by a central X-ray source should lead to an infrared
excess. We used ground-based optical and near-infrared imaging and Spitzer
Space Telescope mid-infrared imaging to search for optical/infrared
counterparts at the X-ray point source positions measured by the Chandra X-Ray
Observatory. We did not detect any counterparts, and hence find no evidence for
fallback disks around any of these sources. In PKS 1209-52, we are able to
exclude a nearby optical/infrared candidate counterpart. In RCW 103, a blend of
3 faint stars at the X-ray source position prevents us from deriving useful
limits. For the other targets, the upper limits on the infrared/X-ray flux
ratio are as deep as (1.0--1.7)$\times 10^{-4}$. Comparing these limits to the
ratio of $\approx 6\times10^{-5}$ measured for 4U 0142+61 (a young pulsar
recently found with an X-ray irradiated dust disk), we conclude that the
non-detection of any disks around young neutron stars studied here are
consistent with their relatively low X-ray luminosities, although we note that
a similar dust disk around the neutron star in Pup A should be detectable by
deeper infrared observations.


title: The Hard X-ray 20-40 keV AGN Luminosity Function

abstract:
  We have compiled a complete extragalactic sample based on 25,000 deg^2 to a
limiting flux of 3E-11 ergs/cm**2/sec (7,000 deg^2 to a flux limit of 1E-11
ergs/cm**2/sec) in the 20 - 40 keV band with INTEGRAL. We have constructed a
detailed exposure map to compensate for effects of non-uniform exposure. The
flux-number relation is best described by a power-law with a slope of alpha =
1.66+-0.11. The integration of the cumulative flux per unit area leads to f =
2.6E-10 ergs/cm**2/sec/sr, which is about 1% of the known 20 - 40 keV X-ray
background. We present the first luminosity function of AGNs in the 20-40 keV
energy range, based on 38 extragalactic objects detected by the imager
IBIS/ISGRI on-board INTEGRAL. The luminosity function shows a smoothly
connected two power-law form, with an index of gamma_1 = 0.8 below, and gamma_2
= 2.1 above the turn-over luminosity of L* = 2.4E43 ergs/sec. The emissivity of
all INTEGRAL AGNs per unit volume is W(> 1E41 ergs/sec) = 2.8E38
ergs/sec/Mpc**3. These results are consistent with those derived in the 2 - 20
keV energy band and do not show a significant contribution by Compton-thick
objects. Because the sample used in this study is truly local (average z =
0.022), only limited conclusions can be drawn for the evolution of AGNs in this
energy band.


title:
VADER - A Satellite Mission Concept For High Precision Dark Energy
  Studies

abstract:
  We present a satellite mission concept to measure the dark energy equation of
state parameter w with percent-level precision. The Very Ambitious Dark Energy
Research satellite (VADER) is a multi-wavelength survey mission joining X-ray,
optical, and IR instruments for a simultaneous spectral coverage from 4microns
(0.3eV) to 10keV over a field of view (FoV) of 1 square degree. VADER combines
several clean methods for dark energy studies, the baryonic acoustic
oscillations in the galaxy and galaxy cluster power spectrum and weak lensing,
for a joint analysis over an unrivalled survey volume. The payload consists of
two XMM-like X-ray telescopes with an effective area of 2,800cm^2 at 1.5keV and
state-of-the-art wide field DEPFET pixel detectors (0.1-10keV) in a curved
focal plane configuration to extend the FoV. The X-ray telescopes are
complemented by a 1.5m optical/IR telescope with 8 instruments for simultaneous
coverage of the same FoV from 0.3 to 4 microns. The 8 dichroic-separated bands
(u,g,r,z,J,H,K,L) provide accurate photometric galaxy redshifts, whereas the
diffraction-limited resolution of the central z-band allows precise shape
measurements for cosmic shear analysis.
  The 5 year VADER survey will cover a contiguous sky area of 3,500 square
degrees to a depth of z~2 and will yield accurate photometric redshifts and
multi-wavelength object parameters for about 175,000 galaxy clusters, one
billion galaxies, and 5 million AGN. VADER will not only provide unprecedented
constraints on the nature of dark energy, but will additionally extend and
trigger a multitude of cosmic evolution studies to very large (>10 Gyrs)
look-back times.


title: Lookback time as a test for brane cosmology

abstract:
  The observed late-time acceleration of the Universe may be the result of
unknown physical processes involving either modifications of gravitation theory
or the existence of new fields in high energy physics. In the former case, such
modifications are usually related to the possible existence of extra dimensions
(which is also required by unification theories), giving rise to the so-called
brane cosmology. In this paper we investigate the viability of this idea by
considering a particular class of brane scenarios in which a large scale
modification of gravity arises due to a gravitational \emph{leakage} into extra
dimensions. To this end, differently from other recent analyses, we combine
\emph{orthogonal} age and distance measurements at intermediary and high
redshifts. We use observations of the lookback time to galaxy clusters,
indirect estimates of the age of the Universe from the most recent Large-Scale
Structure (LSS) and Cosmic Microwave Background (CMB) data, along with the
recent detection of the baryon acoustic oscillations at $z = 0.35$. In
agreement with other recent analyses we show that, although compatible with
these age and distance measurements, a spatially closed scenario is largely
favoured by the current observational data. By restricting our analysis to a
spatially flat universe, we also find that the standard $\Lambda$CDM model is
favoured over the particular braneworld scenario here investigated.


title: X-ray Spectroscopy of the Contact Binary VW Cephei

abstract:
  Short-period binaries represent extreme cases in the generation of stellar
coronae via a rotational dynamo. Such stars are important for probing the
origin and nature of coronae in the regimes of rapid rotation and activity
saturation. VW Cep (P=0.28 d) is a relatively bright, partially eclipsing, and
very active object. Light curves made from Chandra/HETGS data show flaring and
rotational modulation, but no eclipses. Velocity modulation of emission lines
indicates that one component dominates the X-ray emission. The emission measure
is highly structured, having three peaks. Helium-like triplet lines give
electron densities of about 3.0E+10 - 18.0E+10 /cm^3. We conclude that the
corona is predominantly on the polar regions of the primary star and compact.


title:
The Joint Efficient Dark-energy Investigation (JEDI): Measuring the
  cosmic expansion history from type Ia supernovae

abstract:
  JEDI (Joint Efficient Dark-energy Investigation) is a candidate
implementation of the NASA-DOE Joint Dark Energy Mission (JDEM). JEDI will
probe dark energy in three independent methods: (1) type Ia supernovae, (2)
baryon acoustic oscillations, and (3) weak gravitational lensing. In an
accompanying paper, an overall summary of the JEDI mission is given. In this
paper, we present further details of the supernova component of JEDI. To derive
model-independent constraints on dark energy, it is important to precisely
measure the cosmic expansion history, H(z), in continuous redshift bins from z
\~ 0-2 (the redshift range in which dark energy is important). SNe Ia at z > 1
are not readily accessible from the ground because the bulk of their light has
shifted into the near-infrared where the sky background is overwhelming; hence
a space mission is required to probe dark energy using SNe. Because of its
unique near-infrared wavelength coverage (0.8-4.2 microns), JEDI has the
advantage of observing SNe Ia in the rest frame J band for the entire redshift
range of 0 < z < 2, where they are less affected by dust, and appear to be
nearly perfect standard candles. During the first year of JEDI operations,
spectra and light curves will be obtained for ~4,000 SNe Ia at z < 2. The
resulting constraints on dark energy are discussed, with special emphasis on
the improved precision afforded by the rest frame near-infrared data.


title: New Approaches for Modeling Type Ia Supernovae

abstract:
  Type Ia supernovae (SNe Ia) are the largest thermonuclear explosions in the
Universe. Their light output can be seen across great distances and has led to
the discovery that the expansion rate of the Universe is accelerating. Despite
the significance of SNe Ia, there are still a large number of uncertainties in
current theoretical models. Computational modeling offers the promise to help
answer the outstanding questions. However, even with today's supercomputers,
such calculations are extremely challenging because of the wide range of length
and time scales. In this paper, we discuss several new algorithms for
simulations of SNe Ia and demonstrate some of their successes.


title: Neutral gas density in Damped Lyman Alpha systems

abstract:
  We estimate the intrinsic neutral gas density in Damped Lyman Alpha systems
($\Omega_{HI}^{(DLA)}$) in the redshift range $ 2.2 \lesssim z \lesssim 5$ from
the DLA SDSS DR_3 sample of optically selected quasars. We take into account
self-consistently the obscuration on background quasars due to the dust present
in Damped Lyman Alpha systems. We model the column density and redshift
distribution of these systems by using both a non-parametric and a parametric
approach. Under conservative assumptions on the dust content of Damped Lyman
$\alpha$ systems, we show that selection effects lead to underestimating the
intrinsic neutral gas density by at least $15\%$ with respect to the observed
neutral gas density. Over the redshift range $[2.2;5.5]$ we find
$\Omega_{HI}^{(DLA)}=0.97^{+0.08+0.28}_{-0.06-0.15} \cdot 10^{-3}$, where the
first set of error bars gives the $1\sigma$ random errors and the second set
gives the modeling uncertainty dependent on the fraction of metals in dust -
from 0\% to 50\%. This value compares with
$\Omega_{HI}^{(DLA)}=0.82^{+0.05}_{-0.05}$ ($1\sigma$ error bars), which is
obtained when no correction for dust is introduced. In the model with half of
the metals mass in dust we cannot constraint $\Omega_{HI}^{(DLA)}$ at a
confidence level higher than $90\%$. In this case there is indeed a probability
of about $10\%$ that the intrinsic column density distribution of DLA systems
is a power law $f(N_{HI}) \propto 1/N_{HI}^{~1.95}$. In contrast, with $25 \%$
of the metals in dust - the most realistic estimate - a power law is ruled out
at $99.5\%$ of confidence level.


title: A Universal Magnetic Helicity Integral

abstract:
  A magnetic helicity integral is proposed which can be applied to domains
which are not magnetically closed, i.e. have a non-vanishing normal component
of the magnetic field on the boundary. In contrast to the relative helicity
integral, which was previously suggested for magnetically open domains, it does
not rely on a reference field and thus avoids all problems related to the
choice of a particular reference field. Instead it uses a gauge condition on
the vector potential, which corresponds to a particular topologically unique
closure of the magnetic field in the external space. The integral has
additional elegant properties and is easy to compute numerically in practice.
For magnetically closed domains it reduces to the classical helicity integral.


title:
Multi-wavelength properties of the high-energy bright Seyfert 1 galaxy
  IGR J18027-1455

abstract:
  A new sample of hard X-ray sources in the Galactic Plane is being revealed by
the regular observations performed by the INTEGRAL satellite. The full
characterization of these sources is mandatory to understand the hard X-ray
sky. Here we report new multifrequency radio, infrared and optical observations
of the source IGR J18027-1455, as well as a multi-wavelength study from radio
to hard X-rays. The radio counterpart of IGR J18027-1455 is not resolved at any
observing frequency. The radio flux density is well fitted by a simple power
law with a spectral index alpha=-0.75+/-0.02. This value is typical of
optically thin non-thermal synchrotron emission originated in a jet. The NIR
and optical spectra show redshifted emission lines with z=0.034, and a broad
Halpha line profile with FWHM ~3400 km/s. This suggests an Active Galactic
Nucleus (AGN) of type 1 as the optical counterpart of IGR J18027-1455. We
confirm the Seyfert 1 nature of the source, which is intrinsically bright at
high energies both in absolute terms and when scaled to a normalized 6 cm
luminosity. Finally, comparing its X-ray luminosity with isotropic indicators,
we find that the source is Compton thin and AGN dominated. This indicates that
INTEGRAL might have just seen the tip of the iceberg, and several tens of such
sources should be unveiled during the course of its lifetime.


title:
The Morphological Diversities Among Star-forming Galaxies at High
  Redshifts in the Great Observatories Origins Deep Survey (GOODS)

abstract:
  We have used the HST/ACS images to identify 4700 Lyman break galaxies (LBGs)
in GOODS. We present the results from a parametric analysis of the 2-D surface
brightness profiles, for 1333 LBGs at z > 2.5 with rest-frame UV(1600 Angstrom)
AB magnitude < -20.5. Based on the Sersic index, n, which measures the profile
shape, we find that about 40% of LBGs at z=3 have light profiles close to
exponential, and only 30% have the high concentrations seen for spheroids.
About 30% of LBGs appear to have multiple cores or disturbed morphologies
suggestive of close pairs or on-going mergers. The fraction of spheroid-like (n
> 2.5) LBGs decreases by about 15% from z = 5 to 3. A comparison of LBGs with
the starburst galaxies at z = 1.2, shows that the fraction of spheroid-like
profiles is about 20% higher among LBGs. The ellipticity distribution for LBGs
exhibits a pronounced skew towards high ellipticities (> 0.5), which cannot be
explained by morphologies similar to the local disks and spheroids viewed at
random orientations. The peak of the distribution evolves toward lower
ellipticities, from 0.7 at z = 4 to 0.5 at z = 3. At z = 1.2 the distribution
is relatively flat as seen among the present-day galaxies. The dominance of
elongated morphologies among LBGs suggests that in a significant fraction of
them we may be witnessing star-formation in clumps along gas-rich filaments, or
the earliest gas-rich bars that encompass essentially the entire visible
galaxy. Similar features are found to be ubiquitous in hydrodynamical
simulations in which galaxy formation at high redshifts occurs in filamentary
inflows of dynamically cold gas within the dark matter halos, and involves gas-
rich mergers.


title:
Reconstruction of Neutrino-Induced Hadronic and Electromagnetic Showers
  with the ANTARES Experiment

abstract:
  The ANTARES neutrino telescope is being constructed at a site off the French
Mediterranean coast at a depth of 2400m. When high energy neutrinos interact in
water, the charged secondary particles produce Cherenkov light which can be
measured in photomultiplier tubes. Different event signatures are possible;
this work introduces a reconstruction algorithm for events with a hadronic and
potentially an electromagnetic shower producing a signal in the detector. An
algorithm for the combined reconstruction of shower direction and energy is
described, based on a maximum likelihood fit which matches the signal expected
in the photomultipliers for an assumed direction and energy with the signal
actually measured.


title: The luminosity-redshift relation in brane-worlds: I. Analytical results

abstract:
  The luminosity distance - redshift relation is analytically given for
generalized Randall-Sundrum type II brane-world models containing dark
radiation. The derived expressions contain both elementary functions and
elliptic integrals of the first and second kind. First we derive the relation
for models with the Randall-Sundrum fine-tuning. Then we generalize the method
for models with cosmological constant. The analytical results are suitable for
testing brane-world models when future supernova data at higher redshifts will
be available.


title: The Clustering of Massive Halos

abstract:
  The clustering properties of dark matter halos are a firm prediction of
modern theories of structure formation. We use two large volume,
high-resolution N-body simulations to study how the correlation function of
massive dark matter halos depends upon their mass and formation history. We
find that halos with the lowest concentrations are presently more clustered
than those of higher concentration, the size of the effect increasing with halo
mass; this agrees with trends found in studies of lower mass halos. The
clustering dependence on other characterizations of the full mass accretion
history appears weaker than the effect with concentration. Using the integrated
correlation function, marked correlation functions, and a power-law fit to the
correlation function, we find evidence that halos which have recently undergone
a major merger or a large mass gain have slightly enhanced clustering relative
to a randomly chosen population with the same mass distribution.


title:
A Catalog of Spectroscopically Confirmed White Dwarfs from the Sloan
  Digital Sky Survey Data Release 4

abstract:
  We present a catalog of 9316 spectroscopically confirmed white dwarfs from
the Sloan Digital Sky Survey Data Release 4. We have selected the stars through
photometric cuts and spectroscopic modeling, backed up by a set of visual
inspections. Roughly 6000 of the stars are new discoveries, roughly doubling
the number of spectroscopically confirmed white dwarfs. We analyze the stars by
performing temperature and surface gravity fits to grids of pure hydrogen and
helium atmospheres. Among the rare outliers are a set of presumed helium-core
DA white dwarfs with estimated masses below 0.3 Msun, including two candidates
that may be the lowest masses yet found. We also present a list of 928 hot
subdwarfs.


title: Fundamental parameters of six neglected old open clusters

abstract:
  In this paper we present the first $BVI$ CCD photometry of six overlooked old
open clusters (Berkeley 44, NGC 6827, Berkeley 52, Berkeley 56, Skiff 1 and
Berkeley 5) and derive estimates of their fundamental parameters by using
isochrones from the Padova library (Girardi et al. 2000). We found that all the
clusters are older than the Hyades, with ages ranging from 0.8 (NGC 6827 and
Berkeley 5) to 4.0 (Berkeley 56) Gyr. This latter is one of the old open
clusters with the largest heliocentric distance. In the field of Skiff 1 we
recognize a faint blue Main Sequence identical to the one found in the
background of open clusters in the Second and Third Galactic Quadrant, and
routinely attributed to the Canis Major accretion event. We use the synthetic
Color Magnitude Diagram method and a Galactic model to show that this
population can be easily interpreted as Thick Disk and Halo population toward
Skiff 1. We finally revise the old open clusters age distribution, showing that
the previously suggested peak at 5 Gyr looses importance as additional old
clusters are discovered.


title: Hot DB White Dwarfs from the Sloan Digital Sky Survey

abstract:
  We present ugriz photometry and optical spectroscopy for 28 DB and DO white
dwarfs with temperatures between 28,000K and 45,000K. About 10 of these are
particularly well-observed; the remainder are candidates. These are the hottest
DB stars yet found, and they populate the "DB gap" between the hotter DO stars
and the familiar DB stars cooler than 30,000K. Nevertheless, after carefully
matching the survey volumes, we find that the ratio of DA stars to DB/DO stars
is a factor of 2.5 larger at 30,000 K than at 20,000 K, suggesting that the "DB
gap" is indeed deficient and that some kind of atmospheric transformation takes
place in roughly 10% of DA stars as they cool from 30,000 K to 20,000 K.


title:
Nonlinear Structure Formation and "Apparent" Acceleration: an
  Investigation

abstract:
  We present an analytically solvable nonlinear model of structure formation in
a Universe with only dust. The model is an LTB solution (of General Relativity)
and structures are shells of different density. We show that the luminosity
distance-redshift relation has significant corrections at low redshift when the
density contrast becomes nonlinear. A minimal effect is a correction in
apparent magnitudes of order 0.15. We discuss different possibilities that
could further enhance this effect and mimick Dark Energy.


title: Cosmological Evolution of the Duty Cycle of Quasars

abstract:
  Quasars are powered by accretion onto supermassive black holes, but the
problem of the duty cycle related to the episodic activity of the black holes
remains open as one of the major questions of cosmological evolution of
quasars. In this Letter, we obtain quasar duty cycles based on analyses of a
large sample composed of 10,979 quasars with redshifts $z\le2.1$ from the Sloan
Digital Sky Survey (SDSS) Data Release Three. We estimate masses of quasar
black holes and obtain their mass function (MF) of the present sample. We then
get the duty cycle $\bar{\delta}(z)=10^{-3}\sim 1$ based on the So{\l}tan's
argument, implying that black holes are undergoing multiple episodic activity.
We find that the duty cycle has a strong evolution. By comparison, we show that
evolution of the duty cycle follows the history of cosmic star formation rate
(SFR) density in the Universe, providing intriguing evidence for a natural
connection between star formation and triggering of black hole activity.
Feedback on star formation from black hole activity is briefly discussed.


title: FUSE observations of HD 5980: The wind structure of the eruptor

abstract:
  HD 5980 is a unique system containing one massive star (star A) that is
apparently entering the luminous blue variable phase, and an eclipsing
companion (star B) that may have already evolved beyond this phase to become a
Wolf-Rayet star. In this paper we present the results from FUSE observations
obtained in 1999, 2000, and 2002 and one far-UV observation obtained by
ORFEUS/BEFS in 1993 shortly before the first eruption of HD 5980. The eight
phase-resolved spectra obtained by FUSE in 2002 are analyzed in the context of
a wind-eclipse model. This analysis shows that the wind of the eruptor obeyed a
very fast velocity law in 2002, which is consistent with the line-driving
mechanism. Large amplitude line-profile variations on the orbital period are
shown to be due to the eclipse of star B by the wind of star A, although the
eclipse due to gas flowing in the direction of star B is absent. This can only
be explained if the wind of star A is not spherically symmetric, or if the
eclipsed line radiation is "filled-in" by emission originating from somewhere
else in the system, e.g., in the wind-wind collision region. Except for a
slightly lower wind speed, the ORFEUS/BEFS spectrum is very similar to the
spectrum obtained by FUSE at the same orbital phase: there is no indication of
the impending eruption. However, the trend for decreasing wind velocity
suggests the occurrence of the "bi-stability" mechanism, which in turn implies
that the restructuring of the circumbinary environment caused by the transition
from "fast, rarefied wind" to "slow, dense wind" was observed as the eruptive
event. The underlying mechanism responsible for the long-term decrease in wind
velocity that precipitated this change remains an open issue.


title:
Contribution of GRB Emission to the GeV Extragalactic Diffuse Gamma-Ray
  Flux

abstract:
  TeV gamma rays emitted by GRBs are converted into electron-positron pairs via
interactions with the extragalactic infrared radiation fields. In turn the
pairs produced, whose trajectories are randomized by magnetic fields, will
inverse Compton scatter off the cosmic microwave background photons. The beamed
TeV gamma ray flux from GRBs is thus transformed into a GeV isotropic gamma ray
flux, which contributes to the total extragalactic gamma-ray background
emission. Assuming a model for the extragalactic radiation fields, for the GRB
redshift distribution and for the GRB luminosity function, we evaluate the
contribution of the GRB prompt and scattered emissions to the measured
extragalactic gamma-ray flux. To estimate this contribution we optimistically
require that the energy flux at TeV energies is about 10 times stronger than
the energy flux at MeV energies. The resulting gamma-ray diffuse background is
only a small fraction of what is observed, allowing blazars and other sources
to give the dominant contribution.


title:
Radio and X-ray Properties of Relativistic Beaming Models for
  Ultra-Luminous X-ray Sources

abstract:
  We calculate the broadband radio--X-ray spectra predicted by microblazar and
microquasar models for Ultra-Luminous X-ray sources (ULXs), exploring the
possibility that their dominant power-law component is produced by a
relativistic jet, even at near-Eddington mass accretion rates. We do this by
first constructing a generalized disk--jet theoretical framework in which some
fraction of the total accretion power Pa is efficiently removed from the
accretion disk by a magnetic torque responsible for jet formation. Thus, for
different black hole masses, mass accretion rates and magnetic coupling
strength, we self-consistently calculate the relative importance of the
modified disk spectrum, as well as the overall jet emission due to synchrotron
and Compton processes. In general, transferring accretion power to a jet makes
the disk fainter and cooler than a standard disk at the same mass accretion
rate; this may explain why the soft spectral component appears less prominent
than the dominant power-law component in most bright ULXs. We show that the
apparent X-ray luminosity and spectrum predicted by the microquasar model are
consistent with the observed properties of most ULXs. We predict that the radio
synchrotron jet emission is too faint to be detected at the typical threshold
of radio surveys to date. This is consistent with the high rate of
non-detections over detections in radio counterpart searches. Conversely, we
conclude that the observed radio emission found associated with a few ULXs
cannot be due to beamed synchrotron emission from a relativistic jet.


title:
Constraining a possible time-variation of the gravitational constant
  through "gravitochemical heating" of neutron stars

abstract:
  A hypothetical time-variation of the gravitational constant $G$ would cause
neutron star matter to depart from beta equilibrium, due to the changing
hydrostatic equilibrium. This forces non-equilibrium beta processes to occur,
which release energy that is invested partly in neutrino emission and partly in
heating the stellar interior. Eventually, the star arrives at a stationary
state in which the temperature remains nearly constant, as the forcing through
the change of $G$ is balanced by the ongoing reactions. Comparing the surface
temperature of the nearest millisecond pulsar, PSR J0437-4715, inferred from
ultraviolet observations, with our predicted stationary temperature, we
estimate two upper limits for this variation: (1) $|\dot G/G| < 2 \times
10^{-10}$ yr$^{-1}$, if we allow direct Urca reactions operating in the neutron
star core, and (2) $|\dot G/G| < 4 \times 10^{-12}$ yr$^{-1}$, considering only
modified Urca reactions. Both results are competitive with those obtained by
other methods, with (2) being among the most restrictive.


title: Pico: Parameters for the Impatient Cosmologist

abstract:
  We present a fast, accurate, robust and flexible method of accelerating
parameter estimation. This algorithm, called Pico, can compute the CMB power
spectrum and matter transfer function as well as any computationally expensive
likelihoods in a few milliseconds. By removing these bottlenecks from parameter
estimation codes, Pico decreases their computational time by 1 or 2 orders of
magnitude. Pico has several important properties. First, it is extremely fast
and accurate over a large volume of parameter space. Furthermore, its accuracy
can continue to be improved by using a larger training set. This method is
generalizable to an arbitrary number of cosmological parameters and to any
range of l-values in multipole space. Pico is approximately 3000 times faster
than CAMB for flat models, and approximately 2000 times faster then the WMAP 3
year likelihood code. In this paper, we demonstrate that using Pico to compute
power spectra and likelihoods produces parameter posteriors that are very
similar to those using CAMB and the official WMAP3 code, but in only a fraction
of the time. Pico and an interface to CosmoMC are made publicly available at
http://www.astro.uiuc.edu/~bwandelt/pico/.