title:
Comparison of 13CO Line and Far-Infrared Continuum Emission as a
  Diagnostic of Dust and Molecular Gas Physical Conditions: II. The
  Simulations: Testing the Method

abstract:
  The reliability of modeling the far-IR continuum to 13CO J=1-0 spectral line
ratios applied to the Orion clouds (Wall 2006) is tested by applying the models
to simulated data. The two-component models are found to give the dust-gas
temperature difference, $\DT$, to within 1 or 2$ $K. However, other parameters
like the column density per velocity interval and the gas density can be wrong
by an order of magnitude or more. In particular, the density can be
systematically underestimated by an order of magnitude or more. The overall
mass of the clouds is estimated correctly to within a few percent.
  The one-component models estimate the column density per velocity interval
and density within factors of 2 or 3, but their estimates of $\DT$ can be wrong
by 20$ $K. They also underestimate the mass of the clouds by 40-50%.
  These results may permit us to reliably constrain estimates of the Orion
clouds' physical parameters, based on the real observations of the far-IR
continuum and 13CO J=1-0 spectral line. Nevertheless, other systematics must be
treated first. These include the effects of background/foreground subtraction,
effects of the HI component of the ISM, and others. These will be discussed in
a future paper (Wall 2006a).


title:
Comparison of 13CO Line and Far-Infrared Continuum Emission as a
  Diagnostic of Dust and Molecular Gas Physical Conditions: III. Systematic
  Effects and Scientific Implications

abstract:
  Far-infrared continuum data from the {\it COBE}/{\it DIRBE} instrument were
combined with Nagoya 4-m $\cOone$ spectral line data to infer the
multiparsec-scale physical conditions in the Orion$ $A and B molecular clouds,
using 140$\um$/240$\um$ dust color temperatures and the 240$\um$/$\cOone$
intensity ratios. In theory, the ratio of far-IR, submillimeter, or millimeter
continuum to that of a $\cO$ (or $\Co$) rotational line can place reliable
upper limits on the temperature of the dust and molecular gas on multi-parsec
scales; on such scales, both the line and continuum emission are optically
thin, resulting in a continuum-to-line ratio that suffers no loss of
temperature sensitivity in the high-temperature limit as occurs for ratios of
CO rotational lines or ratios of continuum emission in different wavelength
bands. Two-component models fit the Orion data best, where one has a
fixed-temperature and the other has a spatially varying temperature. The former
represents gas and dust towards the surface of the clouds that are heated
primarily by a very large-scale (i.e. $\sim 1 $kpc) interstellar radiation
field. The latter represents gas and dust at greater depths into the clouds and
are shielded from this interstellar radiation field and heated by local stars.
The inferred physical conditions are consistent with those determined from
previously observed maps of $\COone$ and $\Jtwo$ that cover the entire Orion$
$A and B molecular clouds. The models require that the dust-gas temperature
difference is 0$\pm 2 $K. If this surprising result applies to much of the
Galactic ISM, except in unusual regions such as the Galactic Center, then there
are a number implications.


title:
A Rich Population of X-ray Emitting Wolf-Rayet Stars in the Galactic
  Starburst Cluster Westerlund 1

abstract:
  Recent optical and IR studies have revealed that the heavily-reddened
starburst cluster Westerlund 1 (Wd 1) contains at least 22 Wolf-Rayet (WR)
stars, comprising the richest WR population of any galactic cluster. We present
results of a senstive Chandra X-ray observation of Wd 1 which detected 12 of
the 22 known WR stars and the mysterious emission line star W9. The fraction of
detected WN stars is nearly identical to that of WC stars. The WN stars WR-A
and WR-B as well as W9 are exceptionally luminous in X-rays and have similar
hard heavily-absorbed spectra with strong Si XIII and S XV emission lines. The
luminous high-temperature X-ray emission of these three stars is characteristic
of colliding wind binary systems but their binary status remains to be
determined. Spectral fits of the X-ray bright sources WR-A and W9 with
isothermal plane-parallel shock models require high absorption column densities
log N$_{H}$ = 22.56 (cm$^{-2}$) and yield characteristic shock temperatures
kT_shock ~ 3 keV (T ~ 35 MK).


title:
Coronal Emission Measures and Abundances for Moderately Active K Dwarfs
  Observed by Chandra

abstract:
  We have used Chandra to resolve the nearby 70 Oph (K0 V+K5 V) and 36 Oph (K1
V+K1 V) binary systems for the first time in X-rays. The LETG/HRC-S spectra of
all four of these stars are presented and compared with an archival LETG
spectrum of another moderately active K dwarf, Epsilon Eri. Coronal densities
are estimated from O VII line ratios and emission measure distributions are
computed for all five of these stars. We see no substantial differences in
coronal density or temperature among these stars, which is not surprising
considering that they are all early K dwarfs with similar activity levels.
However, we do see significant differences in coronal abundance patterns.
Coronal abundance anomalies are generally associated with the first ionization
potential (FIP) of the elements. On the Sun, low-FIP elements are enhanced in
the corona relative to high-FIP elements, the so-called "FIP effect." Different
levels of FIP effect are seen for our stellar sample, ranging from 70 Oph A,
which shows a prominent solar-like FIP effect, to 70 Oph B, which has no FIP
bias at all or possibly even a weak inverse FIP effect. The strong abundance
difference exhibited by the two 70 Oph stars is unexpected considering how
similar these stars are in all other respects (spectral type, age, rotation
period, X-ray flux). It will be difficult for any theoretical explanation for
the FIP effect to explain how two stars so similar in all other respects can
have coronae with different degrees of FIP bias. Finally, for the stars in our
sample exhibiting a FIP effect, a curious difference from the solar version of
the phenomenon is that the data seem to be more consistent with the high-FIP
elements being depleted in the corona rather than a with a low-FIP enhancement


title:
Simultaneous Measurement of Ionization and Scintillation from Nuclear
  Recoils in Liquid Xenon as Target for a Dark Matter Experiment

abstract:
  We report the first measurements of the absolute ionization yield of nuclear
recoils in liquid xenon, as a function of energy and electric-field.
Independent experiments were carried out with two dual-phase time projection
chamber prototypes, developed for the XENON Dark Matter project. We find that
the charge yield increases with decreasing recoil energy, and exhibits only a
weak field dependence. These results are a first demonstration of the
capability of dual phase xenon detectors to discriminate between electron and
nuclear recoils, a key requirement for a sensitive dark matter search at recoil
energies down to 20 keV.


title:
The Ep,i - Eiso correlation in GRBs: updated observational status,
  re-analysis and main implications

abstract:
  The correlation between the cosmological rest-frame nuFnu spectrum peak
energy, Ep,i, and the isotropic equivalent radiated energy, Eiso, discovered by
Amati et al. in 2002 and confirmed/extended by subsequent osbervations, is one
of the most intriguing and debated observational evidences in Gamma-Ray Bursts
(GRB) astrophysics. In this paper I provide an update and a re-analysis of the
Ep,i - Eiso correlation basing on an updated sample consisting of 41 long
GRBs/XRFs with firm estimates of z and observed peak energy, Ep,obs, 12 GRBs
with uncertain valeus of z and/or Ep,obs, 2 short GRBs with firm estimates of z
and Ep,obs and the peculiar sub-energetic events GRB980425/SN1998bw and
GRB031203/SN2003lw. In addition to standard correlation analysis and power-law
fitting, the data analysis here reported includes a modelization which accounts
for sample variance. All 53 classical long GRBs and XRFs, including 11 Swift
events with published spectral parameters and fluences, have Ep,i and Eiso
values, or upper/lower limits, consistent with the correlation, which shows a
chance probability as low as ~7x10{-15}, a slope of ~0.57 (~0.5 when fitting by
accounting for sample variance) and an extra-Poissonian logarithmic dispersion
of ~0.15, it extends over ~5 orders of magnitude in Eiso and ~3 orders of
magnitude in Ep,i and holds from the closer to the higher z GRBs. I also
discuss the main implications of the updated Ep,i - Eiso correlation for the
models of the physics and geometry of GRB emission, its use for discriminating
different classes and as a pseudo-z estimator, and the tests of possible
selection effects with GRBs of unknown redshift.


title: Monte Carlo simulations of H2 formation on stochastically heated grains

abstract:
  Continuous-time, random-walk Monte Carlo simulations of H2 formation on
grains have been performed for surfaces that are stochastically heated by
photons. We have assumed diffuse cloud conditions and used a variety of grains
of varying roughness and size based on olivine. The simulations were performed
at different optical depths. We confirmed that small grains (r <= 0.02 micron)
have low modal temperatures with strong fluctuations, which have a large effect
on the efficiency of the formation of molecular hydrogen. The grain size
distribution highly favours small grains and therefore H2 formation on these
particles makes a large contribution to the overall formation rate for all but
the roughest surfaces. We find that at A_V=0 only the roughest surfaces can
produce the required amount of molecular hydrogen, but by A_V=1, smoother
surfaces are possible alternatives. Use of a larger value for the evaporation
energy of atomic hydrogen, but one still consistent with experiment, allows
smoother surfaces to produce more H2.


title: Stopping Cooling Flows with Jets

abstract:
  We describe 2D gasdynamical models of jets that carry mass as well as energy
to the hot gas in galaxy clusters. These flows have many attractive attributes
for solving the galaxy cluster cooling flow problem: Why the hot gas
temperature and density profiles resemble cooling flows but show no spectral
evidence of cooling to low temperatures. Using an approximate model for the
cluster A1795, we show that mass-carrying jets can reduce the overall cooling
rate to or below the low values implied by X-ray spectra. Biconical
subrelativistic jets, described with several ad hoc parameters, are assumed to
be activated when gas flows toward or cools near a central supermassive black
hole. As the jets proceed out from the center they entrain more and more
ambient gas. The jets lose internal pressure by expansion and are compressed by
the ambient cluster gas, becoming rather difficult to observe. For a wide
variety of initial jet parameters and several feedback scenarios the global
cooling can be suppressed for many Gyrs while maintaining cluster temperature
profiles similar to those observed. The intermittancy of the feedback generates
multiple generations of X-ray cavities similar to those observed in the Perseus
Cluster and elsewhere.


title: GRB 051221A and Tests of Lorentz Symmetry

abstract:
  Various approaches to quantum gravity suggest the possibility of violation of
Lorentz symmetry at very high energies. In these cases we expect a modification
at low energies of the dispersion relation of photons that contains extra
powers of the momentum suppressed by a high energy scale. These terms break
boost invariance and can be tested even at relatively low energies. We use the
light curves of the very bright short Gamma-Ray Burst GRB 051221A and compare
the arrival times of photons at different energies with the expected time delay
due to a modified dispersion relation. As no time delay was observed, we set a
lower bound of 0.0066 E_{pl} \sim 0.66 10^{17} GeV on the scale of Lorentz
invariance violation.


title: Did Swift measure GRB prompt emission radii?

abstract:
  The Swift X-Ray Telescope often observes a rapidly decaying X-ray emission
stretching to as long as $ t \sim 10^3$ seconds after a conventional prompt
phase. This component is most likely due to a prompt emission viewed at large
observer angles $\theta > 1/\Gamma$, where $\theta\sim 0.1$ is a typical
viewing angle of the jet and$\Gamma\geq 100$ is the Lorentz factor of the flow
during the prompt phase. This can be used to estimate the prompt emission
radii, $r_{em} \geq 2 t c/\theta^2 \sim 6 \times 10^{15}$ cm. These radii are
much larger than is assumed within a framework of a fireball model. Such large
emission radii can be reconciled with a fast variability, on time scales as
short as milliseconds, if the emission is beamed in the bulk outflow frame,
e.g. due to a random relativistic motion of ''fundamental emitters''. This may
also offer a possible explanation for X-ray flares observed during early
afterglows.


title:
Spectral Energy Distributions and Multiwavelength Selection of Type 1
  Quasars

abstract:
  We present an analysis of the mid-infrared (MIR) and optical properties of
type 1 (broad-line) quasars detected by the Spitzer Space Telescope. The MIR
color-redshift relation is characterized to z=3, with predictions to z=7. We
demonstrate how combining MIR and optical colors can yield even more efficient
selection of active galactic nuclei (AGN) than MIR or optical colors alone.
Composite spectral energy distributions (SEDs) are constructed for 259 quasars
with both Sloan Digital Sky Survey and Spitzer photometry, supplemented by
near-IR, GALEX, VLA and ROSAT data where available. We discuss how the spectral
diversity of quasars influences the determination of bolometric luminosities
and accretion rates; assuming the mean SED can lead to errors as large as a
factor of 2 for individual quasars. Finally, we show that careful consideration
of the shape of the mean quasar SED and its redshift dependence leads to a
lower estimate of the fraction of reddened/obscured AGNs missed by optical
surveys as compared to estimates derived from a single mean MIR to optical flux
ratio.


title: Aberration of the Cosmic Microwave Background

abstract:
  The motion of the solar system barycenter with respect to the cosmic
microwave background (CMB) induces a very large apparent dipole component into
the CMB brightness map at the 3 mK level. In this Letter we discuss another
kinematic effect of our motion through the CMB: the small shift in apparent
angular positions due to the aberration of light. The aberration angles are
only of order beta ~0.001, but this leads to a potentially measurable
compression (expansion) of the spatial scale in the hemisphere toward (away
from) our motion through the CMB. In turn, this will shift the peaks in the
acoustic power spectrum of the CMB by a factor of order 1 +/- beta. For current
CMB missions, and even those in the foreseeable future, this effect is small,
but should be taken into account. In principle, if the acoustic peak locations
were not limited by sampling noise (i.e., the cosmic variance), this effect
could be used to determine the cosmic contribution to the dipole term.


title:
Full-Polarization Observations of OH Masers in Massive Star-Forming
  Regions: II. Maser Properties and the Interpretation of Polarization

abstract:
  We analyze full-polarization VLBA data of ground-state, main-line OH masers
in 18 massive star-forming regions previously presented in a companion paper.
The OH masers often arise in the shocked neutral gas surrounding ultracompact
Hii regions. Magnetic fields as deduced from OH maser Zeeman splitting are
highly ordered, both on the scale of a source as well as the maser clustering
scale of ~10^15 cm. Results from our large sample show that this clustering
scale appears to be universal to these masers. OH masers around ultracompact
Hii regions live ~10^4 years and then turn off abruptly, rather than weakening
gradually with time. These masers have a wide range of polarization properties.
At one extreme (e.g., W75 N), pi-components are detected and the polarization
position angles of maser spots show some organization. At the other extreme
(e.g., W51 e1/e2), almost no linear polarization is detected and total
polarization fractions can be substantially less than unity. A typical source
has properties intermediate to these two extremes. In contrast to the well
ordered magnetic field inferred from Zeeman splitting, there is generally no
clear pattern in the distribution of polarization position angles. This can be
explained if Faraday rotation in a typical OH maser source is large on a maser
amplification length but small on a single (e-folding) gain length. Increasing
or decreasing Faraday rotation by a factor of ~5 among different sources can
explain the observed variation in polarization properties. We suggest that
almost all pi-components acquire a signficant amount of circular polarization
from low-gain stimulated emission of a sigma-component from OH appropriately
shifted in velocity and lying along the propagation path.


title:
Color, Structure, and Star Formation History of Dwarf Galaxies over the
  last ~3 Gyr with GEMS and SDSS

abstract:
  We present a study of the colors, structural properties, and star formation
histories for a sample of ~1600 dwarfs over look-back times of ~3 Gyr
(z=0.002-0.25). The sample consists of 401 distant dwarfs drawn from the Galaxy
Evolution from Morphologies and SEDs (GEMS) survey, which provides high
resolution Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)
images and accurate redshifts, and of 1291 dwarfs at 10-90 Mpc compiled from
the Sloan Digitized Sky Survey (SDSS). The sample is complete down to an
effective surface brightness of 22 mag arcsec^-2 in z and includes dwarfs with
M_g=-18.5 to -14 mag. Rest-frame luminosities in Johnson UBV and SDSS ugr
filters are provided by the COMBO-17 survey and structural parameters have been
determined by S\'ersic fits. We find that the GEMS dwarfs are bluer than the
SDSS dwarfs by ~0.13 mag in g-r, which is consistent with the color evolution
over ~2 Gyr of star formation histories involving moderate starbursts and long
periods of continuous star formation. The full color range of the samples
cannot be reproduced by single starbursts of different masses or long periods
of continuous star formation alone. Furthermore, an estimate of the mechanical
luminosities needed for the gas in the GEMS dwarfs to be completely removed
from the galaxies shows that a significant number of low luminosity dwarfs are
susceptible to such a complete gas loss, if they would experience a starburst.
On the other hand, a large fraction of more luminous dwarfs is likely to retain
their gas. We also estimate the star formation rates per unit area for the GEMS
dwarfs and find good agreement with the values for local dwarfs.


title: On the transfer of resonant-line radiation in mesh simulations

abstract:
  The last decade has seen applications of Adaptive Mesh Refinement (AMR)
methods for a wide range of problems from space physics to cosmology. With the
advent of these methods, in which space is discretized into a mesh of many
individual cubic elements, the contemporary analog of the extensively studied
line radiative transfer (RT) in a semi-infinite slab is that of RT in a cube.
In this study we provide an approximate solution of the RT equation, as well as
analytic expressions for the probability distribution functions (pdfs) of the
properties of photons emerging from a cube, and compare them with the
corresponding slab problem. These pdfs can be used to perform fast
resonant-line RT in optically thick AMR cells where, otherwise, it could take
unrealistically long times to transfer even a handful of photons.


title:
Discovery of a Cool Planet of 5.5 Earth Masses Through Gravitational
  Microlensing

abstract:
  In the favoured core-accretion model of formation of planetary systems, solid
planetesimals accumulate to build up planetary cores, which then accrete
nebular gas if they are sufficiently massive. Around M-dwarf stars (the most
common stars in our Galaxy), this model favours the formation of Earth-mass to
Neptune-mass planets with orbital radii of 1 to 10 astronomical units (AU),
which is consistent with the small number of gas giant planets known to orbit
M-dwarf host stars. More than 170 extrasolar planets have been discovered with
a wide range of masses and orbital periods, but planets of Neptune's mass or
less have not hitherto been detected at separations of more than 0.15 AU from
normal stars. Here we report the discovery of a 5.5 (+5.5/-2.7) M_earth
planetary companion at a separation of 2.6 (+1.5/-0.6) AU from a 0.22
(+0.21/-0.11) M_solar M-dwarf star. (We propose to name it OGLE-2005-BLG-390Lb,
indicating a planetary mass companion to the lens star of the microlensing
event.) The mass is lower than that of GJ876d, although the error bars overlap.
Our detection suggests that such cool, sub-Neptune-mass planets may be more
common than gas giant planets, as predicted by the core accretion theory.


title: Electron-positron pair production in the electrosphere of quark stars

abstract:
  We study Schwinger pair creation of charged particles due to the
inhomogeneous electric field created by the thin electron layer at the surface
of quark stars (the electrosphere). As suggested earlier, due to the low photon
emissivity of the quark-gluon plasma and of the electrosphere,
electron-positron pair emission could be the main observational signature of
quark stars. To obtain the electron-positron pair creation rate we use the
tunnelling approach. Explicit expressions for the fermion creation rate per
unit time per unit volume are derived, which generalize the classical Schwinger
result. The finite size effects in pair production, due to the presence of a
boundary (the surface of the quark star), are also considered in the framework
of a simple approach. It is shown that the boundary effects induce large
quantitative and qualitative deviations of the particle production rate from
what one deduces with the Schwinger formula and its generalization for the
electric field of the electrosphere. The electron-positron pair emissivity and
flux of the electrosphere of quark stars due to pair creation is considered,
and the magnitude of the boundary effects for this parameters is estimated. Due
to the inhomogeneity of the electric field distribution in the electrosphere
and of the presence of the boundary effects, at high temperatures ($T\geq
T_{cr}\approx 0.1 $ MeV) we find a lower electron-positron flux as previously
estimated. The numerical value of the critical temperature $T_{cr}$ depends on
the surface potential of the star. We briefly consider the effect of the
magnetic field on the pair creation process and show that the magnetic field
can enhance drastically the pair creation rate.


title: Hubble Space Telescope H-Band Imaging Survey of Massive Gas-Rich Mergers

abstract:
  We report the results from a deep HST NICMOS H-band imaging survey of a
carefully selected sample of 33 luminous, late-stage galactic mergers at z <
0.3. Signs of a recent galactic interaction are seen in all of the objects in
the HST sample, including all 7 IR-excess Palomar-Green (PG) QSOs in the
sample. Unsuspected double nuclei are detected in 5 ULIRGs. A detailed
two-dimensional analysis of the surface brightness distributions in these
objects indicates that the great majority (81%) of the single-nucleus systems
show a prominent early-type morphology. However, low-surface-brightness
exponential disks are detected on large scale in at least 4 of these sources.
The hosts of 'warm' AGN-like systems are of early type and have less pronounced
merger-induced morphological anomalies than the hosts of cool systems with
LINER or HII region-like nuclear optical spectral types. The host sizes and
luminosities of the 7 PG~QSOs in our sample are statistically indistinguishable
from those of the ULIRG hosts. In comparison, highly luminous quasars, such as
those studied by Dunlop et al. (2003), have hosts which are larger and more
luminous. The hosts of ULIRGs and PG QSOs lie close to the locations of
intermediate-size (about 1 -- 2 L*) spheroids in the photometric projection of
the fundamental plane of ellipticals, although there is a tendency in our
sample for the ULIRGs with small hosts to be brighter than normal spheroids.
Excess emission from a young stellar population in the ULIRG/QSO hosts may be
at the origin of this difference. Our results provide support for a possible
merger-driven evolutionary connection between cool ULIRGs, warm ULIRGs, and
PG~QSOs although this sequence may break down at low luminosity. (abridged)


title: NLTE spectral analysis of GW Vir pulsators

abstract:
  GW Vir variables are the pulsating members in the spectroscopic class of PG
1159 stars. In order to understand the characteristic differences between
pulsating and non-pulsating PG 1159 stars, we analyse FUSE spectra of eleven
objects, of which six are pulsating, by means of state-of-the-art NLTE model
atmospheres. The numerous metal lines in the FUV spectra of these stars allow a
precise determination of the photospheric parameters. We present here
preliminary results of our analysis.


title:
The frontier of darkness: the cases of GRB 040223, GRB 040422, GRB
  040624

abstract:
  Understanding the reasons for the faintness of the optical/near-infrared
afterglows of the so-called dark bursts is essential to assess whether they
form a subclass of GRBs, and hence for the use of GRBs in cosmology. With VLT
and other ground-based telescopes, we searched for the afterglows of the
INTEGRAL bursts GRB 040223, GRB 040422 and GRB 040624 in the first hours after
the triggers. A detection of a faint afterglow and of the host galaxy in the K
band was achieved for GRB 040422, while only upper limits were obtained for GRB
040223 and GRB 040624, although in the former case the X-ray afterglow was
observed. A comparison with the magnitudes of a sample of afterglows clearly
shows the faintness of these bursts, which are good examples of a population
that an increasing usage of large diameter telescopes is beginning to unveil.


title: Development of Gaseous Tracking Devices for the Search of WIMPs

abstract:
  The Time Projection Chamber (TPC) has been recognized as a potentially
powerful detector for the search of WIMPs by measuring the directions of
nuclear recoils, in which the most convincing signature of WIMPs, caused by the
Earth's motion around the Galaxy, appears.
  We report on the first results of a performance study of the neutron exposure
of our prototype micro-TPC with Ar-C$_2$H$_6$ (90:10) and CF$_4$ gas of 150
Torr.


title:
Discovery of a Featureless X-Ray Spectrum in the Supernova Remnant Shell
  of G330.2+1.0

abstract:
  We report here on the first pointed X-ray observation of the supernova
remnant (SNR) G330.2+1.0. The X-ray morphology is characterized by an extended
shell. Its X-ray spectrum is well represented by a single power-law function
with a photon index of $\gamma\simeq 2.8$ and interstellar absorption of
$n_{\rm H}\simeq2.6\times 10^{22}$[cm$^{-2}$]. We interpret this emission as
synchrotron radiation from accelerated electrons at the SNR shock, as seen in
SN 1006. The surface brightness of the X-ray emission is anti-correlated with
the radio emission, and the power-law spectrum is dominated at the western
shell where the radio emission is weak. The co-existence of two distinct (radio
bright/X-ray faint and radio faint/X-ray bright) shells in a single supernova
remnant challenges our understanding of the particle acceleration and radiation
mechanisms in different interstellar environments. The object may be a good
target for searching TeV gamma-rays and molecular gas surrounding the blast
shock. We also report on the nature of a bright point-like source (AX
J1601-5143) to the south of the SNR.


title: Primordial magnetic fields and CMB anisotropies

abstract:
  Possible signatures of primordial magnetic fields on the Cosmic Microwave
Background (CMB) temperature and polarization anisotropies are reviewed. The
signals that could be searched for include excess temperature anisotropies
particularly at small angular scales below the Silk damping scale, B-mode
polarization, and non-Gaussian statistics. A field at a few nG level produces
temperature anisotropies at the 5 micro Kelvin level, and B-mode polarization
anisotropies 10 times smaller, and is therefore potentially detectable via the
CMB anisotropies. An even smaller field, with B_0 < 0.1 nG, could lead to
structure formation at high redshift z > 15, and hence naturally explain an
early re-ionization of the Universe.


title: Neutrino Astronomy at the South Pole: latest Results from AMANDA-II

abstract:
  AMANDA-II is the largest neutrino telescope collecting data at the moment,
and its main goal is to search for sources of high energy extra-terrestrial
neutrinos. The detection of such sources could give non-controversial evidence
for the acceleration of charged hadrons in cosmic objects like Supernova
Remnants, Micro-quasars, Active Galactic Nuclei or Gamma Ray Bursts. No
significant excess has been found in searching for neutrinos from both
point-like and non-localized sources. However AMANDA-II has significantly
improved analysis techniques for better signal-to-noise optimization. The
km$^3$-scale IceCube telescope will enlarge the observable energy range and
improve the sensitivities of high energy neutrino searches due to its 30 times
larger effective area.


title: Diffuse radio sources in the cluster of galaxies Abell 548b

abstract:
  We report extensive VLA and ATCA observations of the two diffuse radio
sources in the cluster of galaxies Abell 548b, which confirm their
classification as relics. The two relics (named A and B) show similar flux
density, extent, shape, polarization and spectral index and are located at
projected distances of about 430 and 500 kpc from the cluster center, on the
same side of the cluster's X-ray peak. On the basis of spectral indices of
discrete radio sources embedded within the diffuse features, we have attempted
to distinguish emission peaks of the diffuse sources from unrelated sources. We
have found that both relics, in particular the B-relic, show possible fine
structure, when observed at high resolution. Another diffuse source (named C)
is detected close in projection to the cluster center. High-resolution images
show that it contains two discrete radio sources and a diffuse component, which
might be a candidate for a small relic source. The nature and properties of the
diffuse radio sources are discussed. We conclude that they are likely related
to the merger activity in the cluster.


title: The nearest young moving groups

abstract:
  The latest results in the research of forming planetary systems have led
several authors to compile a sample of candidates for searching for planets in
the vicinity of the sun. Young stellar associations are indeed excellent
laboratories for this study, but some of them are not close enough to allow the
detection of planets through adaptive optics techniques. However, the existence
of very close young moving groups can solve this problem. Here we have compiled
the members of the nearest young moving groups, as well as a list of new
candidates from our catalogue of late-type stars possible members of young
stellar kinematic groups, studying their membership through spectroscopic and
photometric criteria.


title: A Model of Cloud Fragmentation

abstract:
  We present a model in which the supersonic motions observed in molecular
clouds are driven by gravitational energy released as large structures fragment
into smaller ones. The fragmentation process begins in large molecular clouds,
and continues down to fragments of a critical mass, at which gravitational
confinement may be replaced by pressure confinement. The power laws that
describe the scaling of density and mass, and number spectra and mass spectra
of the fragments are given in terms of that of the observed velocity dispersion
of the fragments. The results agree reasonably well with observations over the
range from several to about a third of a million solar masses.


title:
First detection of a VHE gamma-ray spectral maximum from a Cosmic
  source: H.E.S.S. discovery of the Vela X nebula

abstract:
  The Vela supernova remnant (SNR) is a complex region containing a number of
sources of non-thermal radiation. The inner section of this SNR, within 2
degrees of the pulsar PSR B0833-45, has been observed by the H.E.S.S. gamma-ray
atmospheric Cherenkov detector in 2004 and 2005. A strong signal is seen from
an extended region to the south of the pulsar, within an integration region of
radius 0.8 deg. around the position (RA = 08h 35m 00s, dec = -45 deg. 36'
J2000.0). The excess coincides with a region of hard X-ray emission seen by the
ROSAT and ASCA satellites. The observed energy spectrum of the source between
550 GeV and 65 TeV is well fit by a power law function with photon index = 1.45
+/- 0.09(stat) +/- 0.2(sys) and an exponential cutoff at an energy of 13.8 +/-
2.3(stat) +/- 4.1(sys) TeV. The integral flux above 1 TeV is (1.28 +/- 0.17
(stat) +/- 0.38(sys)) x 10^{-11} cm^{-2} s^{-1}. This result is the first clear
measurement of a peak in the spectral energy distribution from a VHE gamma-ray
source, likely related to inverse Compton emission. A fit of an Inverse Compton
model to the H.E.S.S. spectral energy distribution gives a total energy in
non-thermal electrons of ~2 x 10^{45} erg between 5 TeV and 100 TeV, assuming a
distance of 290 parsec to the pulsar. The best fit electron power law index is
2.0, with a spectral break at 67 TeV.


title: Cosmic Microwave Background Polarization

abstract:
  Cosmic microwave background (CMB) anisotropy is our richest source of
cosmological information; the standard cosmological model was largely
established thanks to study of the temperature anisotropies. By the end of the
decade, the Planck satellite will close this important chapter and move us
deeper into the new frontier of polarization measurements. Numerous
ground--based and balloon--borne experiments are already forging into this new
territory. Besides providing new and independent information on the primordial
density perturbations and cosmological parameters, polarization measurements
offer the potential to detect primordial gravity waves, constrain dark energy
and measure the neutrino mass scale. A vigorous experimental program is
underway worldwide and heading towards a new satellite mission dedicated to CMB
polarization.


title:
New Relationships between Galaxy Properties and Host Halo Mass, and the
  Role of Feedbacks in Galaxy Formation

abstract:
  We present new relationships between halo masses M_h and several galaxy
properties, including r*-band luminosities L_r, stellar (M_star) and baryonic
masses, stellar velocity dispersions (sigma), and black hole masses (M_BH).
Approximate analytic expressions are given. In the galaxy halo mass range
3*10^(10) M_sun <= M_h <= 3*10^(13) M_sun the M_h-L_r, M_star-M_h, and M_BH-M_h
are well represented by a double power law, with a break at M_h_break~3*10^(11)
M_sun, corresponding to a mass in stars M_star~ 1.2*10^(10) M_sun, to a r*-band
luminosity L_r~ 5*10^9 L_sun, to a stellar velocity dispersion sigma ~ 88 km/s,
and to a black hole mass M_BH~ 9*10^(6) M_sun. The sigma-M_h relation can be
approximated by a single power law, though a double power law is a better
representation. We interpret these relations in terms of the effect of feedback
from supernovae and from the active nucleus on the interstellar medium. We
argue that the break of the power laws occurs at a mass which marks the
transition between the dominance of the stellar and the AGN feedback.


title: Keplerian discs around post-AGB stars: a common phenomenon?

abstract:
  Aims: We aim at showing that the broad-band SED characteristics of our sample
of post-AGB stars are best interpreted, assuming the circumstellar dust is
stored in Keplerian rotating passive discs.
  Methods: We present a homogeneous and systematic study of the Spectral Energy
Distributions (SEDs) of a sample of 51 post-AGB objects. The selection criteria
to define the whole sample were tuned to cover the broad-band characteristics
of known binary post-AGB stars. The whole sample includes 20 dusty RV Tauri
stars from the General Catalogue of Variable Stars (GCVS). We supplemented our
own Geneva optical photometry with literature data to cover a broad range of
fluxes from the UV to the far-IR.
  Results: All the SEDs display very similar characteristics: a large IR excess
with a dust excess starting near the sublimation temperature, irrespective of
the effective temperature of the central star. Moreover, when available, the
long wavelength fluxes show a black-body slope indicative of the presence of a
component of large mm sized grains.
  Conclusions: We argue that in all systems, gravitationally bound dusty discs
are present. The discs must be puffed-up to cover a large opening angle for the
central star and we argue that the discs have some similarity with the passive
discs detected around young stellar objects. We interpret the presence of a
disc to be a signature for binarity of the central object, but this will need
confirmation by long-term monitoring of the radial velocities. We argue that
dusty RV Tauri stars are those binaries which happen to be in the Population II
instability strip.


title:
An efficient technique for pre-selecting low redshift damped Lyman alpha
  systems

abstract:
  The number of z ~ 1 damped Lyman alpha systems (DLAs, log N(HI) >= 20.3) per
unit redshift is approximately 0.1, making them relatively rare objects. Large,
blind QSO surveys for low redshift DLAs are therefore an expensive prospect for
space-borne UV telescopes. Increasing the efficiency of these surveys by
pre-selecting DLA candidates based on the equivalent widths of metal absorption
lines has previously been a successful strategy. However, the success rate of
DLA identification is still only ~ 35% when simple equivalent width cut-offs
are applied, the majority of systems having 19.0 < log N(HI)<20.3. Here we
propose a new way to pre-select DLA candidates. Our technique requires
high-to-moderate resolution spectroscopy of the MgII 2796 transition, which is
easily accessible from the ground for 0.2 < z < 2.4. We define the D-index, the
ratio of the line's equivalent width to velocity spread and measure this
quantity for 19 DLAs and 8 sub-DLAs in archival spectra obtained with echelle
spectrographs. For the majority of absorbers, there is a clear distinction
between the D-index of DLAs compared with sub-DLAs (Kolmogorov-Smirnov
probability = 0.8%). Based on this pilot data sample, we find that the D-index
can select DLAs with a success rate of up to 90%, an increase in selection
efficiency by a factor of 2.5 compared with a simple equivalent width cut. We
test the applicability of the D-index at lower resolution and find that it
remains a good discriminant of DLAs for FWHM < 1.5 A. However, the recommended
D-index cut-off between DLAs and sub-DLAs decreases with poorer resolution and
we tabulate the appropriate D-index values that should be used with spectra of
different resolutions.


title: A Successful Targeted Search for Hypervelocity Stars

abstract:
  Hypervelocity stars (HVSs) travel with velocities so extreme that dynamical
ejection from a massive black hole is their only suggested origin. Following
our discovery of the first HVS, we have undertaken a dedicated survey for more
HVSs in the Galactic halo and present here the resulting discovery of two new
HVSs: SDSS J091301.0+305120 and SDSS J091759.5+672238, traveling with Galactic
rest-frame velocities at least +558+-12 and +638+-12 km/s, respectively.
Assuming the HVSs are B8 main sequence stars, they are at distances ~75 and ~55
kpc, respectively, and have travel times from the Galactic Center consistent
with their lifetimes. The existence of two B8 HVSs in our 1900 deg^2 survey,
combined with the Yu & Tremaine HVS rate estimates, is consistent with HVSs
drawn from a standard initial mass function but inconsistent with HVS drawn
from a truncated mass function like the one in the top-heavy Arches cluster.
The travel times of the five currently known HVSs provide no evidence for a
burst of HVSs from a major in-fall event at the Galactic Center in the last
\~160 Myr.


title: Globular Clusters as a Test for Gravity in the Weak Acceleration Regime

abstract:
  Non-baryonic Dark Matter (DM) appears in galaxies and other cosmic structures
when and only when the acceleration of gravity, as computed considering only
baryons, goes below a well defined value a0=1.2e-8 cm/s/s. This might indicate
a breakdown of Newton's law of gravity (or inertia) below a0, an acceleration
smaller than the smallest probed in the solar system. It is therefore important
to verify whether Newton's law of gravity holds in this regime of
accelerations. In order to do this, one has to study the dynamics of objects
that do not contain significant amounts of DM and therefore should follow
Newton's prediction for whatever small accelerations. Globular clusters are
believed, even by strong supporters of DM, to contain negligible amounts of DM
and therefore are ideal for testing Newtonian dynamics in the low acceleration
limit. Here, we discuss the status of an ongoing program aimed to do this test.
Compared to other studies of globular clsuters, the novelty is that we trace
the velocity dispersion profile of globular clusters far enough from the center
to probe gravitational accelerations well below a0. In all three clusters
studied so far the velocity dispersion is found to remain constant at large
radii rather than follow the Keplerian falloff. On average, the flattening
occurs at the radius where the cluster internal acceleration of gravity is
1.8+-0.4 x 10^{-8} cm/s/s, fully consistent with MOND predictions.


title:
The Bolocam 1.1 mm Lockman Hole Galaxy Survey: SHARC II 350 micron
  Photometry and Implications for Spectral Models, Dust Temperatures, and
  Redshift Estimation

abstract:
  We present 350 micron photometry of all 17 galaxy candidates in the Lockman
Hole detected in a 1.1 mm Bolocam survey. Several of the galaxies were
previously detected at 850 microns, at 1.2 mm, in the infrared by Spitzer, and
in the radio. Nine of the Bolocam galaxy candidates were detected at 350
microns and two new candidates were serendipitously detected at 350 microns
(bringing the total in the literature detected in this way to three). Five of
the galaxies have published spectroscopic redshifts, enabling investigation of
the implied temperature ranges and a comparison of photometric redshift
techniques.
  Lambda = 350 microns lies near the spectral energy distribution peak for z =
2.5 thermally emitting galaxies. Thus, luminosities can be measured without
extrapolating to the peak from detection wavelengths of lambda > 850 microns.
Characteristically, the galaxy luminosities lie in the range 1.0 - 1.2 x 10^13
L_solar, with dust temperatures in the range of 40 K to 70 K, depending on the
choice of spectral index and wavelength of unit optical depth. The implied dust
masses are 3 - 5 x 10^8 M_solar. We find that the far-infrared to radio
relation for star-forming ULIRGs systematically overpredicts the radio
luminosities and overestimates redshifts on the order of Delta z ~ 1, whereas
redshifts based on either on submillimeter data alone or the 1.6 micron stellar
bump and PAH features are more accurate.


title: Far-ultraviolet Observations of the North Ecliptic Pole with SPEAR

abstract:
  We present SPEAR/FIMS far-ultraviolet observations near the North Ecliptic
Pole. This area, at b~30 degrees and with intermediate HI column, seems to be a
fairly typical line of sight that is representative of general processes in the
diffuse ISM. We detect a surprising number of emission lines of many elements
at various ionization states representing gas phases from the warm neutral
medium (WNM) to the hot ionized medium (HIM). We also detect fluorescence bands
of H2, which may be due to the ubiquitous diffuse H2 previously observed in
absorption.


title:
Far-UV Observations of a Thermal Interface in the Orion-Eridanus
  Superbubble

abstract:
  Diffuse far-UV emission arising from the edge of the Orion-Eridanus
superbubble was observed with the SPEAR imaging spectrometer, revealing
numerous emission lines arising from both atomic species and H2. Spatial
variations in line intensities of CIV, SiII, and OVI, in comparison with soft
X-ray, H-alpha and dust data, indicate that these ions are associated with
processes at the interface between hot gas inside the bubble and the cooler
ambient medium. Thus our observations probe physical conditions of an evolved
thermal interface in the ISM.


title: Morpho-kinematic modeling of gaseous nebulae with SHAPE

abstract:
  We present a powerful new tool to analyse and disentangle the 3-D geometry
and kinematic structure of gaseous nebulae. The method consists in combining
commercially available digital animation software to simulate the 3-D structure
and expansion pattern of the nebula with a dedicated, purpose built rendering
software that produces the final images and long slit spectra which are
compared to the real data. We show results for the complex planetary nebulae
NGC 6369 and Abell 30 based on long slit spectra obtained at the San Pedro
Martir observatory.


title: Far Ultraviolet Spectral Images of the Vela Supernova Remnant

abstract:
  We present far-ultraviolet (FUV) spectral-imaging observations of the Vela
supernova remnant (SNR), obtained with the Spectroscopy of Plasma Evolution
from Astrophysical Radiation (SPEAR) instrument, also known as FIMS. The Vela
SNR extends 8 degrees in the FUV and its global spectra are dominated by
shock-induced emission lines. We find that the global FUV line luminosities can
exceed the 0.1-2.5 keV soft X-ray luminosity by an order of magnitude. The
global O VI:C III ratio shows that the Vela SNR has a relatively large fraction
of slower shocks compared with the Cygnus Loop.


title:
The Spectroscopy of Plasma Evolution from Astrophysical Radiation
  Mission

abstract:
  The Spectroscopy of Plasma Evolution from Astrophysical Radiation (or the
Far-ultraviolet Imaging Spectrograph) instruments, flown aboard the STSAT-1
satellite mission, have provided the first large-area spectral mapping of the
cosmic far ultraviolet (FUV, lambda 900-1750 Ang) background. We observe
diffuse radiation from hot (10^4 to 10^6 K) and ionized plasmas, molecular
hydrogen, and dust scattered starlight. These data provide for the
unprecedented detection and discovery of spectral emission from a variety of
interstellar environments, including the general medium, molecular clouds,
supernova remnants, and super-bubbles. We describe the mission and its data,
present an overview of the diffuse FUV sky's appearance and spectrum, and
introduce the scientific findings detailed later in this volume.


title: The SPEAR Instrument and On-Orbit Performance

abstract:
  The SPEAR (or 'FIMS') instrumentation has been used to conduct the first
large-scale spectral mapping of diffuse cosmic far ultraviolet (FUV, 900-1750
AA) emission, including important diagnostics of interstellar hot (10^4 K -
10^6 K) and photoionized plasmas, H_2, and dust scattered starlight. The
instrumentation's performance has allowed for the unprecedented detection of
astrophysical diffuse far UV emission lines. A spectral resolution of 550 and
an imaging resolution of 5' is achieved on-orbit in the Short (900 - 1175 AA)
and Long (1335 - 1750 AA) bandpass channels within their respective 7.4 deg x
4.3' and 4.0 deg x 4.6' fields of view. We describe the SPEAR imaging
spectrographs, their performance, and the nature and handling of their data.


title: Internal Kinematics of Galaxies: 3D Spectroscopy on Russian 6m Telescope

abstract:
  We have considered some results concerning gas and stars kinematics of nearby
galaxies recently obtained on the SAO RAS 6m telescope using the panoramic
spectroscopy methods. The circumnuclear regions of the galaxies were observed
with integral-field spectrograph MPFS. The large-scale ionized gas kinematics
was studied with the scanning Fabry-Perot interferometer (FPI) in the
multi-mode focal reducer SCORPIO. The main attention is given for kinematically
decoupled regions in the galaxies: bars, spirals, polar disks and rings.


title: Molecular Hydrogen Fluorescence in the Eridanus Superbubble

abstract:
  The first FUV (lambda lambda 1350-1750 A) spectral imaging observations of
the Eridanus superbubble, obtained with the SPEAR/FIMS mission, have revealed
distinct fluorescent emission from molecular hydrogen. In this study, the
observed emission features were compared with those from a photo-dissociation
region model with assumed illuminating stellar fields. The result showed rather
high line ratios of I_{1580}/I_{1610}, which may imply the existence of
high-temperature molecular clouds in the region. The H_2 fluorescence intensity
showed a proportional correlation with H-alpha emission, indicating that the
fluorescence and the recombination emission have similar physical origins.


title:
Soft X-ray emission lines of Fe XV in solar flare observations and the
  Chandra spectrum of Capella

abstract:
  Recent calculations of atomic data for Fe XV have been used to generate
theoretical line ratios involving n = 3-4 transitions in the soft X-ray
spectral region (52-83 A), for a wide range of electron temperatures and
densities applicable to solar and stellar coronal plasmas. A comparison of
these with solar flare observations from a rocket-borne spectrograph (XSST)
reveals generally good agreement between theory and experiment. In particular,
the 82.76 A emission line in the XSST spectrum is identified, for the first
time to our knowledge in an astrophysical source. Most of the Fe XV transitions
which are blended have had the species responsible clearly identified, although
there remain a few instances where this has not been possible. The line ratio
calculations are also compared with a co-added spectrum of Capella obtained
with the Chandra satellite, which is probably the highest signal-to-noise
observation achieved for a stellar source in the 25-175 A soft X-ray region.
Good agreement is found between theory and experiment, indicating that the Fe
XV lines are reliably detected in Chandra spectra, and hence may be employed as
diagnostics to determine the temperature and/or density of the emitting plasma.
However the line blending in the Chandra data is such that individual emission
lines are difficult to measure accurately, and fluxes may only be reliably
determined via detailed profile fitting of the observations. The co-added
Capella spectrum is made available to hopefully encourage further exploration
of the soft X-ray region in astronomical sources.


title:
The UKIRT Infrared Deep Sky Survey ZYJHK Photometric System: Passbands
  and Synthetic Colours

abstract:
  The UKIRT Infrared Deep Sky Survey is a set of five surveys of complementary
combinations of area, depth, and Galactic latitude, which began in 2005 May.
The surveys use the UKIRT Wide Field Camera (WFCAM), which has a solid angle of
0.21deg^2. Here we introduce and characterise the ZYJHK photometric system of
the camera, which covers the wavelength range 0.83-2.37 microns. We synthesise
response functions for the five passbands, and compute colours in the WFCAM,
SDSS and 2MASS bands, for brown dwarfs, stars, galaxies and quasars of
different types. We provide a recipe for others to compute colours from their
own spectra. Calculations are presented in the Vega system, and the computed
offsets to the AB system are provided, as well as colour equations between
WFCAM filters and the SDSS and 2MASS passbands. We highlight the opportunities
presented by the new Y filter at 0.97-1.07 microns for surveys for hypothetical
Y dwarfs (brown dwarfs cooler than T), and for quasars of very--high redshift,
z>6.4.


title: On the CMB large-scales angular correlations

abstract:
  We study the large-scale angular correlation signatures of the Cosmic
Microwave Background (CMB) temperature fluctuations from WMAP data in several
spherical cap regions of the celestial sphere, outside the Kp0 or Kp2 cut-sky
masks. We applied a recently proposed method to CMB temperature maps, which
permits an accurate analysis of their angular correlations in the celestial
sphere through the use of normalized histograms of the number of pairs of such
objects with a given angular separation versus their angular separation. The
method allows for a better comparison of the results from observational data
with the expected CMB angular correlations of a statistically isotropic
Universe, computed from Monte Carlo maps according to the WMAP best-fit Lambda
CDM model. We found that the, already known, anomalous lack of large-scale
power in full-sky CMB maps are mainly due to missing angular correlations of
quadrupole-like signature. This result is robust with respect to frequency CMB
maps and cut-sky masks. Moreover, we also confirm previous results regarding
the unevenly distribution in the sky of the large-scale power of WMAP data. In
a bin-to-bin correlations analyses, measured by the full covariance matrix
chi^2 statistic, we found that the angular correlations signatures in opposite
Galactic hemispheres are anomalous at the 98%-99% confidence level.


title: Weak Gravitational Lensing of the CMB

abstract:
  Weak gravitational lensing has several important effects on the cosmic
microwave background (CMB): it changes the CMB power spectra, induces
non-Gaussianities, and generates a B-mode polarization signal that is an
important source of confusion for the signal from primordial gravitational
waves. The lensing signal can also be used to help constrain cosmological
parameters and lensing mass distributions. We review the origin and calculation
of these effects. Topics include: lensing in General Relativity, the lensing
potential, lensed temperature and polarization power spectra, implications for
constraining inflation, non-Gaussian structure, reconstruction of the lensing
potential, delensing, sky curvature corrections, simulations, cosmological
parameter estimation, cluster mass reconstruction, and moving lenses/dipole
lensing.


title: Faint emission lines in the Galactic H II regions M16, M20 and NGC 3603

abstract:
  We present deep echelle spectrophotometry of the Galactic {\hii} regions M16,
M20 and NGC 3603. The data have been taken with the Very Large Telescope
Ultraviolet-Visual Echelle Spectrograph in the 3100 to 10400 \AA range. We have
detected more than 200 emission lines in each region. Physical conditions have
been derived using different continuum and line intensity ratios. We have
derived He$^{+}$, C$^{++}$ and O$^{++}$ abundances from pure recombination
lines as well as abundances from collisionally excited lines for a large number
of ions of different elements. We have obtained consistent estimations of the
temperature fluctuation parameter, {\ts}, using different methods. We also
report the detection of deuterium Balmer lines up to D$\delta$ (M16) and to
D$\gamma$ (M20) in the blue wings of the hydrogen lines, which excitation
mechanism seems to be continuum fluorescence. The temperature fluctuations
paradigm agree with the results obtained from optical CELs and the more
uncertain ones from far IR fine structure CELs in NGC 3603, although, more
observations covering the same volume of the nebula are necessary to obtain
solid conclusions.


title:
Energy balance in two phase models for temperature fluctuations in HII
  regions

abstract:
  Aims. The main objective of this article is to provide a simple physical
framework with permits a quantitative comparison of measurements of the
temperature fluctuations in the ionized interstellar medium with possible
mechanisms which can produce them. Methods. We assume a generalized two phase
ISM and derive expressions relating the mean amplitude of the temperature
fluctuations to the temperatures of the phases and to the energy input, in
excess of the basic component due to photoionization, required to maintain
them. We apply these expressions to a set of limiting cases for the temperature
and density differences between the phases. Finally we compare the most
plausible case with the most complete data set available: the temperature
fluctuations observed in the Orion Nebula. Results. We first list the cases
considered and our general inferences: (a) Very hot tenuous substrate and warm
moderately dense clouds; discarded as requiring too much excess energy input.
(b) Two phases with equal densities but different temperatures, both warm;
feasible but not general. (c) Two warm phases at moderately different
temperatures and densities; the most probable case. This case is then used to
quantify a specific hypothesis, reconnection of turbulent magnetic fields, as
the source of the fluctuations observed in the Orion Nebula. Field strengths of
a few hundred microG are required, not out of line with the limited
observations available. Time variability on scales of months is a testable
prediction of the scenario.


title: Small scale contributions to CMB: A coherent analysis

abstract:
  We reanalyse Cosmic Microwave Background data from experiments probing both
large and small scales. We assume that measured anisotropies are due not only
to primary fluctuations but also, especially at small scales, to secondary
effects (namely the Sunyaev-Zel'dovich effect) and possible point source
contaminations. We first consider primary and secondary anisotropies only. For
the first time in such analyses, the cosmological dependence of secondary
fluctuations is fully taken into account. We show in that case that a higher
value of the normalisation $\sigma\_8$ is preferred, as found by previous
studies, but also higher values of the optical depth $\tau$ and power spectrum
index $n\_s$ are needed. In the second part of our analysis, we further include
possible contaminations from unresolved and unremoved point sources. Under
these considerations, we discuss the effects on the cosmological parameters. We
further obtain the best combination of relative contributions of the three
kinds of sources to the measured microwave power on small scales at each
frequency. Our method allows us to simultaneously obtain cosmological
parameters and explain the so-called small scale power excess in a consistent
way.


title: Dynamical dark energy with a constant vacuum energy density

abstract:
  We present a holographic dark-energy model in which the Newton constant
$G_{N}$ scales in such a way as to render the vacuum energy density a true
constant. Nevertheless, the model acts as a dynamical dark-energy model since
the scaling of $G_{N}$ goes at the expense of deviation of concentration of
dark-matter particles from its canonical form and/or of promotion of their mass
to a time-dependent quantity, thereby making the effective equation of state
(EOS) variable and different from -1 at the present epoch. Thus the model has a
potential to naturally underpin Dirac's suggestion for explaining the
large-number hypothesis, which demands a dynamical $G_{N}$ along with the
creation of matter in the universe. We show that with the aid of observational
bounds on the variation of the gravitational coupling, the effective-field
theory IR cutoff can be strongly restricted, being always closer to the future
event horizon than to the Hubble distance. As for the observational side, the
effective EOS restricted by observation can be made arbitrary close to -1, and
therefore the present model can be considered as a ``minimal'' dynamical
dark-energy scenario. In addition, for nonzero but small curvature
$(|\Omega_{k0}| \lsim 0.003)$, the model easily accommodates a transition
across the phantom line for redshifts $z \lsim 0.2 $, as mildly favored by the
data. A thermodynamic aspect of the scenario is also discussed.


title: Andromeda X, A New Dwarf Spheroidal Satellite of M31: Photometry

abstract:
  We report the discovery of Andromeda X, a new dwarf spheroidal satellite of
M31, based on stellar photometry from the Sloan Digital Sky Survey (SDSS).
Using follow-up imaging data we have estimated its distance and other physical
properties. We find that Andromeda X has a dereddened central surface
brightness of mu_V,0 ~ 26.7 mag arcsec^-2 and a total apparent magnitude of
V_tot ~ 16.1, which at the derived distance modulus, (m - M)_0 ~ 24.12 - 24.34,
yields an absolute magnitude of M_V ~ -8.1 +/- 0.5; these values are quite
comparable to those of Andromeda IX, a previously-discovered low luminosity M31
satellite. The discoveries of Andromeda IX and Andromeda X suggest that such
extremely faint satellites may be plentiful in the Local Group.


title:
Statistical Mechanics of the Self-Gravitating Gas: Thermodynamic Limit,
  Unstabilities and Phase Diagrams

abstract:
  We show that the self-gravitating gas at thermal equilibrium has an infinite
volume limit in the three ensembles (GCE, CE, MCE) when (N, V) -> infty,
keeping N/V^{1/3} fixed, that is, with eta = G m^2 N/[ V^{1/3} T] fixed. We
develop MonteCarlo simulations, analytic mean field methods (MF) and low
density expansions. We compute the equation of state and find it to be locally
p(r) = T rho_V(r), that is a local ideal gas equation of state. The system is
in a gaseous phase for eta < eta_T = 1.51024...and collapses into a very dense
object for eta > eta_T in the CE with the pressure becoming large and negative.
The isothermal compressibility diverges at eta = eta_T. We compute the
fluctuations around mean field for the three ensembles. We show that the
particle distribution can be described by a Haussdorf dimension 1 < D < 3.

categories: astro-ph cond-mat.stat-mech gr-qc hep-th


title:
Self-Gravitating Phase Transitions: Point Particles, Black Holes and
  Strings

abstract:
  We compute the quantum string entropy S_s(m,j) of the microscopic string
states of mass m and spin j in two physically relevant backgrounds: Kerr
(rotating) black holes and de Sitter (dS) space-time. We find a new formula for
the quantum gravitational entropy S_{sem} (M, J), as a function of the usual
Bekenstein-Hawking entropy S_{sem}^(0)(M, J). We compute the quantum string
emission by a black hole in de Sitter space-time (bhdS). In all these cases:
(i) strings with the highest spin, and (ii) in dS space-time, (iii) quantum
rotating black holes, (iv) quantum dS regime, (v) late bhdS evaporation, we
find a new gravitational phase transition with a common distinctive universal
feature: A square root branch point singularity in any space-time dimensions.
This is the same behavior as for the thermal self-gravitating gas of point
particles (de Vega-Sanchez transition), thus describing a new universality
class.


title: Production of antimatter in the galaxy

abstract:
  The astronomical dark matter could be made of weakly interacting massive
species whose mutual annihilations should produce antimatter particles and
distortions in the corresponding energy spectra. The propagation of cosmic rays
inside the Milky Way plays a crucial role and is briefly presented. The
uncertainties in its description lead to considerable variations in the
predicted primary fluxes. This point is illustrated with antiprotons. Finally,
the various forthcoming projects are rapidly reviewed with their potential
reach.


title:
Multi-Dimensional Simulations of the Accretion-Induced Collapse of White
  Dwarfs to Neutron Stars

abstract:
  We present 2.5D radiation-hydrodynamics simulations of the accretion-induced
collapse (AIC) of white dwarfs, starting from 2D rotational equilibrium
configurations of a 1.46-Msun and a 1.92-Msun model. Electron capture leads to
the collapse to nuclear densities of these cores within a few tens of
milliseconds. The shock generated at bounce moves slowly, but steadily,
outwards. Within 50-100ms, the stalled shock breaks out of the white dwarf
along the poles. The blast is followed by a neutrino-driven wind that develops
within the white dwarf, in a cone of ~40deg opening angle about the poles, with
a mass loss rate of 5-8 x 10^{-3} Msun/yr. The ejecta have an entropy on the
order of 20-50 k_B/baryon, and an electron fraction distribution that is
bimodal. By the end of the simulations, at >600ms after bounce, the explosion
energy has reached 3-4 x 10^{49}erg and the total ejecta mass has reached a few
times 0.001Msun. We estimate the asymptotic explosion energies to be lower than
10^{50}erg, significantly lower than those inferred for standard core collapse.
The AIC of white dwarfs thus represents one instance where a neutrino mechanism
leads undoubtedly to a successful, albeit weak, explosion.
  We document in detail the numerous effects of the fast rotation of the
progenitors: The neutron stars are aspherical; the ``nu_mu'' and anti-nu_e
neutrino luminosities are reduced compared to the nu_e neutrino luminosity; the
deleptonized region has a butterfly shape; the neutrino flux and electron
fraction depend strongly upon latitude (a la von Zeipel); and a quasi-Keplerian
0.1-0.5-Msun accretion disk is formed.


title: OH maser disc and outflow in the Orion-BN/KL region

abstract:
  MERLIN measurements of 1.6-GHz OH masers associated with Orion-BN/KL are
presented, and the data are compared with data on other masers, molecular
lines, compact radio continuum sources and infrared sources in the region. OH
masers are detected over an area 30 arcsec in diameter, with the majority lying
along an approximately E-W structure that extends for approx. 18~arcsec,
encompassing the infrared sources IRc2, IRc6 and IRc7. Radial velocities range
from -13 to +42 km/s. The system of OH masers shows a velocity gradient
together with non-circular motions. The kinematics are modelled in terms of an
expanding and rotating disc or torus. The rotation axis is found to be in the
same direction as the molecular outflow. There is an inner cavity of radius
approx 1300 au with no OH masers. The inner cavity, like the water `shell'
masers and SiO masers, is centred on radio source I. Some of the OH masers
occur in velocity-coherent strings or arcs that are longer than 5~arcsec (2250
au). One such feature, Stream A, is a linear structure at position angle approx
45 degree, lying between IRc2 and BN. We suggest that these masers trace shock
fronts, and have appeared, like a vapour trail, 200 yr after the passage of the
runaway star BN. The radio proper motions of BN, source I and source n project
back to a region near the base of Stream A that is largely devoid of OH masers.
The 1612-MHz masers are kinematically distinct from the other OH masers. They
are also more widely distributed and appear to be associated with the outflow
as traced by water masers and by the 2.12-micron emission from shocked H2 The
magnetic field traced by the OH masers ranges from 1.8 to 16.3 mG, with a
possible reversal. No OH masers were found associated with even the most
prominent proplyds within 10 arcsec of Theta1 Ori C.


title: Velocity field and star formation in the Horsehead nebula

abstract:
  Using large scale maps in C18O(2-1) and in the continuum at 1.2mm obtained at
the IRAM-30m antenna with the Heterodyne Receiver Array (HERA) and MAMBO2, we
investigated the morphology and the velocity field probed in the inner layers
of the Horsehead nebula. The data reveal a non--self-gravitating (m/mvir = 0.3)
filament of dust and gas (the "neck", diameter = 0.15-0.30 pc) connecting the
Horsehead western ridge, a Photon-Dominated Region illuminated by sigmaOri, to
its parental cloud L1630. Several dense cores are embedded in the ridge and the
neck. One of these cores appears particularly peaked in the 1.2 mm continuum
map and corresponds to a feature seen in absorption on ISO maps around 7 micr.
Its \cdo emission drops at the continuum peak, suggestive of molecular
depletion onto cold grains. The channel maps of the Horsehead exhibit an
overall north-east velocity gradient whose orientation swivels east-west,
showing a somewhat more complex structure than was recently reported by
\cite{pound03} using BIMA CO(1-0) mapping. In both the neck and the western
ridge, the material is rotating around an axis extending from the PDR to L1630
(angular velocity=1.5-4.0 km/s). Moreover, velocity gradients along the
filament appear to change sign regularly (3 km/s/pc, period=0.30 pc) at the
locations of embedded integrated intensity peaks. The nodes of this oscillation
are at the same velocity. Similar transverse cuts across the filament show a
sharp variation of the angular velocity in the area of the main dense core. The
data also suggest that differential rotation is occurring in parts of the
filament. We present a new scenario for the formation and evolution of the
nebula and discuss dense core formation inside the filament.


title:
The photometric evolution of dissolving star clusters I: First
  predictions

abstract:
  We calculated the broad-band photometric evolution of unresolved star
clusters, including the preferential loss of low-mass stars due to mass
segregation. The stellar mass function of a cluster evolves due to three
effects: (a) the evolution of massive stars; (b) early tidal effects reduce the
mass function independently of the stellar mass; (c) after mass segregation has
completed, tidal effects preferentially remove the lowest-mass stars from the
cluster. Results: (1) During the first ~40% of the lifetime of a cluster the
cluster simply gets fainter due to the loss of stars by tidal effects. (2)
Between ~40 and ~80% of its lifetime the cluster gets bluer due to the loss of
low-mass stars. This will result in an underestimate of the age of clusters if
standard cluster evolution models are used (0.15 -- 0.5 dex). (3) After ~80% of
the total lifetime of a cluster it will rapidly get redder. This is because
stars at the low-mass end of the main sequence, which are preferentially lost,
are bluer than the AGB stars that dominate the light at long wavelengths,
resulting in an age overestimate. (4) Clusters with mass segregation and the
preferential loss of low-mass stars evolve along almost the same tracks in
colour-colour diagrams as clusters without mass segregation. Therefore it will
be difficult to distinguish this effect from that due to the cluster age for
unresolved clusters, unless the total lifetime of the clusters can be
estimated. (5) The changes in the colour evolution of unresolved clusters due
to the preferential loss of low-mass stars will affect the determination of the
SFHs. (6) The preferential loss of low-mass stars might explain the presence of
old (~13 Gyr) clusters in NGC 4365 which are photometrically disguised as
intermediate-age clusters (2 - 5 Gyr). [Abridged]


title:
Dissipative structures of diffuse molecular gas: I - Broad HCO$^+$(1-0)
  emission

abstract:
  Results: We report the detection of broad HCO+(1-0) lines (10 mK < T < 0.5
K). The interpretation of 10 of the HCO+ velocity components is conducted in
conjunction with that of the associated optically thin 13CO emission. The
derived HCO+ column densities span a broad range, $10^{11}< N(HCO+)/\Delta v <4
\times 10^{12} \rm cm^2/(km/s^{-1}$, and the inferred HCO+ abundances, $2
\times 10^{-10}<X(HCO+) < 10^{-8}$, are more than one order of magnitude above
those produced by steady-state chemistry in gas weakly shielded from UV
photons, even at large densities. We compare our results with the predictions
of non-equilibrium chemistry, swiftly triggered in bursts of turbulence
dissipation and followed by a slow thermal and chemical relaxation phase,
assumed isobaric. The set of values derived from the observations, i.e. large
HCO+ abundances, temperatures in the range of 100--200 K and densities in the
range 100--1000 cm3, unambiguously belongs to the relaxation phase. The
kinematic properties of the gas suggest in turn that the observed HCO+ line
emission results from a space-time average in the beam of the whole cycle
followed by the gas and that the chemical enrichment is made at the expense of
the non-thermal energy. Last, we show that the "warm chemistry" signature (i.e
large abundances of HCO+, CH+, H20 and OH) acquired by the gas within a few
hundred years, the duration of the impulsive chemical enrichment, is kept over
more than thousand years. During the relaxation phase, the \wat/OH abundance
ratio stays close to the value measured in diffuse gas by the SWAS satellite,
while the OH/HCO+ ratio increases by more than one order of magnitude.


title: First detection of Lyman continuum escape from a local starburst galaxy

abstract:
  The dominating reionization source in the young universe has yet to be
identified. Possible candidates include metal poor starburst dwarf galaxies of
which the Blue Compact Galaxy Haro 11 may represent a local counterpart. Using
the Far Ultraviolet Spectroscopic Explorer (FUSE) we obtained spectra of Haro
11 to search for leaking ionizing radiation. A weak signal shortwards of the
Lyman break is identified as Lyman continuum (LyC) emission escaping from the
ongoing starburst. From profile fitting to weak metal lines we derive column
densities of the low ionization species. Adopting a metallicity typical of the
H II regions of Haro 11, the corresponding H I column density is optically
thick in the LyC. Therefore most of the LyC photons must escape through
transparent holes in the interstellar medium. Using spectral evolutionary
models we constrain the escape fraction of the produced LyC photons to between
4 and 10%, assuming a normal Salpeter IMF. We argue that in a hierarchical
galaxy formation scenario, this allows for a substantial contribution to cosmic
reionization by starburst dwarf galaxies at high redshifts.


title: Planets and Asteroids in the gamma Cephei System

abstract:
  The binary star system gamma Cephei is unusual in that it harbours a stable
giant planet around the larger star at a distance only about a tenth of that of
the stellar separation. Numerical simulations are carried out into the
stability of test particles in the system. This provides possible locations for
additional planets and asteroids. To this end, the region interior to the
planet is investigated in detail and found to permit structured belts of
particles. The region between the planet and the secondary star however shows
almost no stability. The existence of an Edgeworth-Kuiper belt analogue is
found to be a possibility beyond 65 au from the barycentre of the system,
although it shows almost no structural features. Finally, the region around the
secondary star is studied for the first time. Here, a zone of stability is seen
out to 1.5 au for a range of inclinations. In addition, a ten Jupiter-mass
planet is shown to remain stable about this smaller star, with the habitability
and observational properties of such an object being discussed.


title: Contact Binaries with Additional Components.I. The Extant Data

abstract:
  We have attempted to establish an observational evidence for presence of
distant companions which may have acquired and/or absorbed the angular momentum
during evolution of multiple systems thus facilitating or enabling formation of
contact binaries. In this preliminary investigation we use several techniques
(some of them distance-independent) and mostly disregard detection biases of
individual techniques in an attempt to establish a lower limit to the frequency
of triple systems. While the whole sample of 151 contact binary stars brighter
than Vmax = 10 mag. gives a firm lower limit of 42+/-5%, the corresponding
number for the much better observed Northern-sky sub-sample is 59+/-8%. These
estimates indicate that most contact binary stars exist in multiple systems.


title: The effect of uncertainties on chemical models of dark clouds

abstract:
  The gas-phase chemistry of dark clouds has been studied with a treatment of
uncertainties caused both by errors in individual rate coefficients and
uncertainties in physical conditions. Moreover, a sensitivity analysis has been
employed to attempt to determine which reactions are most important in the
chemistry of individual species. The degree of overlap between calculated
errors in abundances and estimated observational errors has been used as an
initial criterion for the goodness of the model and the determination of a best
'chemical' age of the source. For the well-studied sources L134N and TMC-1CP,
best agreement is achieved at so-called "early times" ~10$^{5}$ yr, in
agreement with previous calculations but here put on a firmer statistical
foundation. A more detailed criterion for agreement, which takes into account
the degree of disagreement, is also proposed. Poorly understood but critical
classes of reactions are delineated, especially reactions between ions and
polar neutrals. Such reactions will have to be understood better before the
chemistry can be made more secure. Nevertheless, the level of agreement is low
enough to indicate that a static picture of physical conditions without
consideration of interactions with grain surfaces is inappropriate for a
complete understanding of the chemistry.


title:
Two-body problem with the cosmological constant and observational
  constraints

abstract:
  We discuss the influence of the cosmological constant on the gravitational
equations of motion of bodies with arbitrary masses and eventually solve the
two-body problem. Observational constraints are derived from measurements of
the periastron advance in stellar systems, in particular binary pulsars and the
solar system. Up to now, Earth and Mars data give the best constraint, Lambda <
10^{-36} km^{-2}; bounds from binary pulsars are potentially competitive with
limits from interplanetary measurements. If properly accounting for the
gravito-magnetic effect, this upper limit on $\Lambda$ could greatly improve in
the near future thanks to new data from planned or already operating
space-missions.


title:
Formation of a Partially-Screened Inner Acceleration Region in Radio
  Pulsars: Drifting Subpulses and Thermal X-Ray Emission from Polar Cap Surface

abstract:
  The subpulse drifting phenomenon in pulsar radio emission is considered
within the partially screened inner gap model, in which the
sub-Goldreich-Julian thermionic flow of iron ions or electrons coexists with
the spark-associated electron-positron plasma flow. We derive a simple formula
that relates the thermal X-ray luminosity $L_{\rm x}$ from the spark-heated
polar cap and the \EB subpulse periodicity $\hat{P}_3$ (polar cap carousel
time). For PSRs B0943+10 and B1133+16, the only two pulsars for which both
$\hat{P}_3$ and $L_{\rm x}$ are known observationally, this formula holds well.
For a few other pulsars, for which only one quantity is measured
observationally, we predict the value of the other quantity and propose
relevant observations that can confirm or discard the model. Then we further
study the detailed physical conditions that allow such partially screened inner
gap to form. By means of the condition $T_{\rm c}/T_{\rm s}>1$ (where $T_{\rm
c}$ is the critical temperature above which the surface delivers a thermal flow
to adequately supply the corotation charge density, and $T_{\rm s}$ is the
actual surface temperature), it is found that a partially-screened gap (PSG)
can be formed given that the near surface magnetic fields are very strong and
curved. We consider both curvature radiation (CR) and resonant inverse Compton
scattering (ICS) to produce seed photons for pair production, and find that the
former is the main agency to produce gamma-rays to discharge PSG.


title: Low Carbon Abundance in Type Ia Supernovae

abstract:
  We investigate the quantity and composition of unburned material in the outer
layers of three normal Type Ia supernovae (SNe Ia): 2000dn, 2002cr and 20 04bw.
Pristine matter from a white dwarf progenitor is expected to be a mixture of
oxygen and carbon in approximately equal abundance. Using near-infrared (NIR,
0.7-2.5 microns) spectra, we find that oxygen is abundant while carbon is
severely depleted with low upper limits in the outer third of the ejected mass.
Strong features from the OI line at rest wavelength = 0.7773 microns are
observed through a wide range of expansion velocities approx. 9,000 - 18,000
km/s. This large velocity domain corresponds to a physical region of the
supernova with a large radial depth. We show that the ionization of C and O
will be substantially the same in this region. CI lines in the NIR are expected
to be 7-50 times stronger than those from OI but there is only marginal
evidence of CI in the spectra and none of CII. We deduce that for these three
normal SNe Ia, oxygen is more abundant than carbon by factors of 100 - 1,000.
MgII is also detected in a velocity range similar to that of OI. The presence
of O and Mg combined with the absence of C indicates that for these SNe Ia,
nuclear burning has reached all but the extreme outer layers; any unburned
material must have expansion velocities greater than 18,000 km/s. This result
favors deflagration to detonation transition (DD) models over pure deflagration
models for SNe Ia.


title: SPEAR Far Ultraviolet Spectral Images of the Cygnus Loop

abstract:
  We present far-ultraviolet (FUV) spectral images, measured at C IV 1550, He
II 1640, Si IV+O IV] 1400, and O III] 1664, of the entire Cygnus Loop, observed
with the Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR)
instrument, also known as FIMS. The spatial distribution of FUV emission
generally corresponds with a limb-brightened shell, and is similar to optical,
radio and X-ray images. The features found in the present work include a
``carrot'', diffuse interior, and breakout features, which have not been seen
in previous FUV studies. Shock velocities of 140-160 km/s is found from a line
ratio of O IV] to O III], which is insensitive not only to resonance scattering
but also to elemental abundance. The estimated velocity indicates that the fast
shocks are widespread across the remnant. By comparing various line ratios with
steady-state shock models, it is also shown that the resonance scattering is
widespread.


title:
A search for magnetic fields in the variable HgMn star $\alpha$
  Andromedae

abstract:
  With this work, we have conducted an extensive search for magnetic fields in
the photosphere of $\alpha$~And. We have acquired new circular polarisation
spectra with the MuSiCoS and ESPaDOnS sp ectropolarimeters. We have also
obtained FORS1 circular polarisation spectra fro m the ESO Archive, and
considered all previously published magnetic data. This e xtensive dataset has
been used to systematically test for the presence of magnet ic fields in the
photosphere of $\alpha$~And. We have also examined the high-res olution spectra
for line profile variability. The polarimetric and magnetic data provide no
convincing evidence for photospheric magnetic fields. The highest-S/N phase-
and velocity-resolved Stokes $V$ profiles, obtained with ESPaDOnS, allow us to
place a $3\sigma$ upper limit of abou t 100~G on the possible presence of any
undetected pure dipolar, quadrupolar or octupolar surface magnet ic fields (and
just 50~G for fields with significant obliquity). We also conside r and dismiss
the possible existence of more complex fossil and dynamo-generated fields, and
discuss the implications of these results for explaining the non-un iform
surface distribution of Hg. The very high-quality ESPaDOnS spectra have al
lowed us to confidently detect variability of Hg~{\sc ii} $\lambda 6149$,
$\lamb da 5425$ and $\lambda 5677$. The profile variability of the Hg~{\sc ii}
lines is strong, and similar to that of the Hg~{\sc ii} $\lambda 3984$ line. On
the ot her hand, variability of other lines (e.g. Mn, Fe) is much weaker, and
appears to be attributable to orbital modulation, continuum normalisation
differences and weak, variable fringing.


title: Stochastic Gravitational Wave Production After Inflation

abstract:
  In many models of inflation, the period of accelerated expansion ends with
preheating, a highly non-thermal phase of evolution during which the inflaton
pumps energy into a specific set of momentum modes of field(s) to which it is
coupled. This necessarily induces large, transient density inhomogeneities
which can source a significant spectrum of gravitational waves. In this paper,
we consider the generic properties of gravitational waves produced during
preheating, perform detailed calculations of the spectrum for several specific
inflationary models, and identify problems that require further study. In
particular, we argue that if these gravitational waves exist they will
necessarily fall within the frequency range that is feasible for direct
detection experiments -- from laboratory through to solar system scales. We
extract the gravitational wave spectrum from numerical simulations of
preheating after $\lambda \phi^4$ and $m_{\phi}^2 \phi^2$ inflation, and find
that they lead to a gravitational wave amplitude of around $\Omega_{gw}h^2\sim
10^{-10}$. This is considerably higher than the amplitude of the primordial
gravitational waves produced during inflation. However, the typical wavelength
of these gravitational waves is considerably shorter than LIGO scales, although
in extreme cases they may be visible at scales accessible to the proposed BBO
mission. We survey possible experimental approaches to detecting any
gravitational wave background generated during preheating.


title: The Surface of 2003EL61 in the Near Infrared

abstract:
  We report the detection of crystalline water ice on the surface of 2003 EL61.
Reflectance spectra were collected from Gemini North telescope from 1.0 to 2.4
micron wavelength range, and from the Keck telescope across the 1.4 to 2.4
micron wavelength range. The signature of crystalline water ice is obvious in
all data collected. Like the surfaces of many outer solar system bodies, the
surface of 2003 EL61 is rich in crystalline water ice, which is energetically
less favored than amorphous water ice at low temperatures, suggesting that
resurfacing processes may be taking place. The near infrared color of the
object is much bluer than a pure water ice model. Adding a near infrared blue
component such as hydrogen cyanide or phyllosilicate clays improves the fit
considerably, with hydrogen cyanide providing the greatest improvement. The
addition of hydrated tholins and bitumens also improves the fit but is
inconsistent with the neutral V-J reflectance of 2003 EL61. A small decrease in
reflectance beyond 2.3 micron may be attributable to cyanide salts. Overall,
the reflected light from 2003 EL61 is best fit by a model of 2/3 to 4/5 pure
crystalline water ice and 1/3 to 1/5 near infrared blue component such as
hydrogen cyanide or kaolinite. The surface of 2003 EL61 is unlikely to be
covered by significant amounts of dark material such as carbon black, as our
pure ice models reproduce published albedo estimates derived from the spin
state of 2003 EL61.


title:
Sub-GeV flashes in $\gamma-$ray burst afterglows as probes of underlying
  bright UV flares

abstract:
  Bright optical and X-ray flares have been observed in many Gamma-ray Burst
(GRB) afterglows. These flares have been attributed to late activity of the
central engine. In most cases the peak energy is not known and it is possible
and even likely that there is a significant far-ultraviolet component. These
far-ultraviolet photons escape our detection because they are absorbed by the
neutral hydrogen before reaching Earth. However, these photons cross the blast
wave produced by the ejecta that have powered the initial GRB. They can be
inverse Compton upscattered by hot electrons within this blast wave. This
process will produce a strong sub-GeV flare that follows the high energy (soft
X-ray) tail of the far-UV flare but lasts much longer and can be detected by
the upcoming {\em Gamma-Ray Large Area Telescope} (GLAST) satellite. This
signature can be used to probe the spectrum of the underlying far-ultraviolet
flare. The extra cooling produced by this inverse Compton process can lower the
X-ray emissivity of the forward shock and explain the unexpected low early
X-ray flux seen in many GRBs.


title:
XMM-Newton View of the z>0 Warm-Hot Intergalactic Medium Toward
  Markarian 421

abstract:
  The recent detection with Chandra of two warm-hot intergalactic medium (WHIM)
filaments toward Mrk 421 by Nicastro et al. provides a measurement of the bulk
of the "missing baryons" in the nearby universe. Since Mrk 421 is a bright
X-ray source, it is also frequently observed by the XMM-Newton Reflection
Grating Spectrometer (RGS) for calibration purposes. Using all available
archived XMM observations of this source with small pointing offsets (<15"), we
construct the highest-quality XMM grating spectrum of Mrk 421 to date with a
net exposure time (excluding periods of high background flux) of 437 ks and
\~15000 counts per resolution element at 21.6A, more than twice that of the
Chandra spectrum. Despite the long exposure time neither of the two intervening
absorption systems is seen, though the upper limits derived are consistent with
the Chandra equivalent width measurements. This appears to result from (1) the
larger number of narrow instrumental features caused by bad detector columns,
(2) the degraded resolution of XMM/RGS as compared to the Chandra/LETG, and (3)
fixed pattern noise at \lambda > 29A. The non-detection of the WHIM absorbers
by XMM is thus fully consistent with the Chandra measurement.


title:
Observational Evidence for the Co-evolution of Galaxy Mergers, Quasars,
  and the Blue/Red Galaxy Transition

abstract:
  We compile a number of observations to estimate the time-averaged rate of
formation or buildup of red sequence galaxies, as a function of mass and
redshift. Comparing this with the mass functions of mergers and quasar hosts,
and independently comparing their clustering properties as a function of
redshift, we find that these populations trace the same mass distribution, with
similar evolution, at redshifts 0<z<~1.5. Knowing one of the quasar, merger, or
elliptical mass/luminosity functions, it is possible to predict the others.
Allowing for greater model dependence, we compare the rate of early-type
buildup with the implied merger and quasar triggering rates as a function of
mass and redshift and find agreement. Over this redshift range, observed merger
fractions can account for the entire bright quasar luminosity function and
buildup of the red sequence at all but the highest masses at low redshift
(>~10^11 M_solar at z<~0.3) where 'dry' mergers appear to dominate. This
supports a necessary prediction of theories where mergers between gas-rich
galaxies produce ellipticals with an associated phase of quasar activity, after
which the remnant becomes red. These populations trace a similar characteristic
transition mass, possibly reflecting the mass above which the elliptical
population is mostly (>~50%) assembled at a given redshift, which increases
with redshift over the observed range in a manner consistent with suggestions
that cosmic downsizing may apply to red galaxy assembly as well as star
formation. These mass distributions as a function of redshift do not uniformly
trace the all/red/blue galaxy population, ruling out models in which quasar
activity is generically associated with star formation or is long lived in
'old' systems.


title:
Deducing the Lifetime of Short Gamma-Ray Burst Progenitors from Host
  Galaxy Demography

abstract:
  The frequency of short gamma-ray bursts (GRBs) in galaxies with distinct star
formation histories can be used to constrain the lifetime of the progenitor
systems. As an illustration, we consider here the constraints that can be
derived from separating the host galaxies into early and late types. On
average, early-type galaxies have their stars formed earlier than late-type
galaxies, and this difference, together with the time delay between progenitor
formation and short GRB outburst, leads to different burst rates in the two
types of hosts. Presently available data suggest, but not yet prove, that the
local short GRB rate in early-type galaxies may be comparable to that in
late-type galaxies. This suggests that, unlike Type Ia supernovae, at least
half of the short GRB progenitors that can outburst within a Hubble time have
lifetimes greater than about 7 Gyr. Models of the probability distribution of
time delays, here parametrized as P(\tau) \propto \tau^n, with n > -1 are
favored. This apparent long time delay and the fact that early-type galaxies in
clusters make a substantial contribution to the local stellar mass inventory
can explain the observed preponderance of short GRBs in galaxy clusters.


title: The magnetic field and confined wind of the O star $\theta^1$~Orionis~C

abstract:
  In this paper we confirm the presence of a globally-ordered, kG-strength
magnetic field in the photosphere of the young O star $\theta^1$~Orionis~C, and
examine the properties of its optical line profile variations. A new series of
high-resolution MuSiCoS Stokes $V$ and $I$ spectra has been acquired which
samples approximately uniformly the rotational cycle of $\theta^1$~Orionis~C.
Using the Least-Squares Deconvolution (LSD) multiline technique, we have
succeeded in detecting variable Stokes $V$ Zeeman signatures associated with
the LSD mean line profile. These signatures have been modeled to determine the
magnetic field geometry. We have furthermore examined the profi le variations
of lines formed in both the wind and photosphere using dynamic spectra. Based
on spectrum synthesis fitting of the LSD profiles, we determine that the polar
strength of the magnetic dipole component is $1150 \la B_{\rm d}\la 1800$~G and
that the magnetic obliquity is $27\degr \la \beta \la 68\degr$, assuming
$i=45\pm 20\degr$. The best-fit values for $i=45\degr$ are $B_{\rm d} = 1300
\pm 150 (1\sigma)$~G and $\beta = 50\degr \pm 6\degr (1\sigma)$. Our data
confirm the previous detection of a magnetic field in this star, and
furthermore demonstrate the sinusoidal variability of the longitudinal field
and accurately determine the phases and intensities of the magnetic extrema.
The analysis of ``photospheric'' and ``wind'' line profile variations supports
previous reports of the optical spectroscopic characteristics, and provides
evidence for infall of material within the magnetic equatorial plane.


title:
Investigation of the magnetic field characteristics of Herbig Ae/Be
  stars: Discovery of the pre-main sequence progenitors of the magnetic Ap/Bp
  stars

abstract:
  We are investigating the magnetic characteristics of pre-main sequence Herbig
Ae/Be stars, with the aim of (1) understanding the origin and evolution of
magnetism in intermediate-mass stars, and (2) exploring the influence of
magnetic fields on accretion, rotation and mass-loss at the early stages of
evolution of A, B and O stars. We have begun by conducting 2 large surveys of
Herbig Ae/Be stars, searching for direct evidence of photospheric magnetic
fields via the longitudinal Zeeman effect. From observations obtained using
FORS1 at the ESO-VLT and ESPaDOnS at the Canada-France-Hawaii Telescope, we
report the confirmed detection of magnetic fields in 4 pre-main sequence A- and
B-type stars, and the apparent (but as yet unconfirmed) detection of fields in
2 other such stars. We do not confirm the detection of magnetic fields in
several stars reported by other authors to be magnetic: HD 139614, HD 144432 or
HD 31649. One of the most evolved stars in the detected sample, HD 72106A,
shows clear evidence of strong photospheric chemical peculiarity, whereas many
of the other (less evolved) stars do not. The magnetic fields that we detect
appear to have surface intensities of order 1 kG, seem to be structured on
global scales, and appear in about 10% of the stars studied. Based on these
properties, these magnetic stars appear to be pre-main sequence progenitors of
the magnetic Ap/Bp stars.


title: Magnetic properties of intermediate-mass stars

abstract:
  Magnetic fields play an important role in producing and modifying the
photospheric chemical peculiarities of intermediate-mass main sequence stars.
This article discusses the basic theory and methods of measurement used to
detect and characterise stellar magnetic fields, and reviews our current
knowledge of selected characteristics of magnetic fields in intermediate-mass
stars.


title:
Magnetic Fields in Starburst Galaxies and The Origin of the FIR-Radio
  Correlation

abstract:
  We estimate minimum energy magnetic fields (B_min) for a sample of galaxies
with measured gas surface densities, spanning from normal spirals to
starbursts. We show that the ratio of the minimum energy magnetic pressure to
the total pressure in the ISM decreases substantially with increasing surface
density; for Arp 220 this ratio is ~10^-4. Therefore, if the minimum energy
estimate is applicable, magnetic fields in starbursts are dynamically weak
compared to gravity, in contrast to normal spiral galaxies. We argue, however,
that rapid cooling of relativistic electrons in starbursts invalidates the
minimum energy estimate. We critically assess a number of independent
constraints on the magnetic field strength in starbursts. In particular, we
argue that the existence of the FIR-radio correlation implies that the
synchrotron cooling timescale for cosmic ray electrons is much shorter than
their escape time from the galactic disk; this in turn implies that the true
magnetic field in starbursts is significantly larger than B_min. The strongest
argument against such large fields is that one might expect starbursts to have
steep radio spectra indicative of strong synchrotron cooling, which is not
observed. We show, however, that ionization and bremsstrahlung losses can
flatten the nonthermal spectra of starburst galaxies even in the presence of
rapid cooling, providing much better agreement with observed spectra. We
further demonstrate that ionization and bremsstrahlung losses are likely to be
important in shaping the radio spectra of most starbursts at GHz frequencies,
thereby preserving the linearity of the FIR-radio correlation. We thus conclude
that magnetic fields in starbursts are significantly larger than B_min. We
highlight several observations that can test this conclusion.