title:
Observing with a space-borne gamma-ray telescope: selected results from
  INTEGRAL

abstract:
  The International Gamma-Ray Astrophysics Laboratory, i.e. the INTEGRAL
satellite of ESA, in orbit since about 3 years, performs gamma-ray observations
of the sky in the 15 keV to 8 MeV energy range. Thanks to its imager IBIS, and
in particular the ISGRI detection plane based on 16384 CdTe pixels, it achieves
an excellent angular resolution (12 arcmin) for point source studies with good
continuum spectrum sensitivity. Thanks to its spectrometer SPI, based on 19
germanium detectors maintained at 85 K by a cryogenic system, located inside an
active BGO veto shield, it achieves excellent spectral resolution of about 2
keV for 1 MeV photons, which permits astrophysical gamma-ray line studies with
good narrow-line sensitivity. In this paper we review some goals of gamma-ray
astronomy from space and present the INTEGRAL satellite, in particular its
instruments ISGRI and SPI. Ground and in-flight calibration results from SPI
are presented, before presenting some selected astrophysical results from
INTEGRAL. In particular results on point source searches are presented,
followed by results on nuclear astrophysics, exemplified by the study of the
1809 keV gamma-ray line from radioactive 26Al nuclei produced by the ongoing
stellar nucleosynthesis in the Galaxy. Finally a review on the study of the
positron-electron annihilation in the Galactic center region, producing 511 keV
gamma-rays, is presented.


title: CO emission from candidate photo-dissociation regions in M81

abstract:
  Context At least a fraction of the atomic hydrogen in spiral galaxies is
suspected to be the result of molecular hydrogen which has been dissociated by
radiation from massive stars.
  Aims In this paper, we extend our earlier set of data from a small region of
the Western spiral arm of M81 with CO observations in order to study the
interplay between the radiation field and the molecular and atomic hydrogen.
  Methods We report CO(1-0) observations with the Nobeyama 45 m dish and the
Owens Valley interferometer array of selected regions in the Western spiral arm
of M81.
  Results From our Nobeyama data, we detect CO(1-0) emission at several
locations, coinciding spatially with HI features near a far-UV source. The
levels and widths of the detected CO profiles are consistent with the CO(1-0)
emission that can be expected from several large photo-dissociation regions
with typical sizes of some 50x150 pc located within our telescope beam. We do
not detect emission at other pointings, even though several of those are near
far-UV sources and accompanied by bright HI. This non-detection is likely a
consequence of the marginal area filling factor of photo-dissociation regions
in our observations. We detect no emission in our Owens Valley data, consistent
with the low intensity of the CO emission detected in that field by the
Nobeyama dish.
  Conclusions We explain the lack of CO(1-0) emission at positions farther from
far-UV sources as a consequence of insufficient heating and excitation of the
molecular gas at these positions, rather than as an absence of molecular
hydrogen.


title: Interacting holographic dark energy

abstract:
  We demonstrate that a transition from decelerated to accelerated cosmic
expansion arises as a pure interaction phenomenon if pressureless dark matter
is coupled to holographic dark energy whose infrared cutoff scale is set by the
Hubble length. In a spatially flat universe the ratio of the energy densities
of both components remains constant through this transition, while it is
subject to slow variations for non-zero spatial curvature. The coincidence
problem is dynamized and reformulated in terms of the interaction rate. An
early matter era is recovered since for negligible interaction at high
redshifts the dark energy itself behaves as matter. A simple model for this
dynamics is shown to fit the SN Ia data. The constant background energy density
ratio simplifies the perturbation analysis which is characterized by
non-adiabatic features.


title: High Accuracy Matching of Planetary Images

abstract:
  We address the question of to what accuracy remote sensing images of the
surface of planets can be matched, so that the possible displacement of
features on the surface can be accurately measured. This is relevant in the
context of the libration experiment aboard the European Space Agency's
BepiColombo mission to Mercury. We focus here only on the algorithmic aspects
of the problem, and disregard all other sources of error (spacecraft position,
calibration uncertainties, etc.) that would have to be taken into account. We
conclude that for a wide range of illumination conditions, translations between
images can be recovered to about one tenth of a pixel r.m.s.


title:
LIINUS/SERPIL: a design study for interferometric imaging spectroscopy
  at the LBT

abstract:
  LIINUS/SERPIL is a design study to augment LBTs interferometric beam combiner
camera LINC-NIRVANA with imaging spectroscopy. The FWHM of the interferometric
main beam at 1.5 micron will be about 10 mas, offering unique imaging and
spectroscopic capabilities well beyond the angular resolution of current 8-10m
telescopes. At 10 mas angular scale, e.g., one resolution element at the
distance of the Galactic Center corresponds to the average diameter of the
Pluto orbit (79 AU), hence the size of the solar system. Taking advantage of
the LBT interferometric beam with an equivalent maximum diameter of 23 m,
LIINUS/SERPIL is an ideal precursor instrument for (imaging) spectrographs at
extremely large full aperture telescopes. LIINUS/SERPIL will be built upon the
LINC-NIRVANA hardware and LIINUS/SERPIL could potentially be developed on a
rather short timescale. The study investigates several concepts for the optical
as well as for the mechanical design. We present the scientific promises of
such an instrument together with the current status of the design study.


title: Water masers in the Local Group of galaxies

abstract:
  We compare the number of detected 22 GHz H2O masers in the Local Group
galaxies M31, M33, NGC6822, IC10, IC1613, DDO187, GR8, NGC185, and the
Magellanic Clouds with the water maser population of the Milky Way. To
accomplish this we searched for water maser emission in the two Local Group
galaxies M33 and NGC6822 using the Very Large Array (VLA) and incorporated
results from previous studies. We observed 62 HII regions in M33 and 36 regions
with H-alpha emission in NGC6822. Detection limits are 0.0015 and 0.0008 Lsun
for M33 and NGC6822, respectively (corresponding to 47 and 50 mJy in three
channels with 0.7 km/s width). M33 hosts three water masers above our detection
limit, while in NGC6822 no maser source was detected. We find that the water
maser detection rates in the Local Group galaxies M31, M33, NGC6822, IC1613,
DDO187, GR8, NGC185, and the Magellanic Clouds are consistent with expectations
from the Galactic water masers if one considers the different star formation
rates of the galaxies. However, the galaxy IC10 exhibits an overabundance of
masers, which may result from a compact central starburst.


title:
Homotopy symmetry in the multiply connected twin paradox of special
  relativity

abstract:
  In a multiply connected space, the two twins of the special relativity twin
paradox move with constant relative speed and meet a second time without
acceleration. The twins' situations appear to be symmetrical despite the need
for one to be younger due to time dilation. Here, the suggestion that the
apparent symmetry is broken by homotopy classes of the twins' worldlines is
reexamined using space-time diagrams. It is found that each twin finds her own
spatial path to have zero winding index and that of the other twin to have
unity winding index, i.e. the twins' worldlines' relative homotopy classes are
symmetrical. Although the twins' apparent symmetry is in fact broken by the
need for the non-favoured twin to non-simultaneously identify spatial domain
boundaries, the non-favoured twin {\em cannot} detect her disfavoured state if
she only measures the homotopy classes of the two twins' projected worldlines,
contrary to what was previously suggested. We also note that for the
non-favoured twin, the fundamental domain can be chosen by identifying time
boundaries (with a spatial offset) instead of space boundaries (with a temporal
offset).


title: First observations with CONDOR, a 1.5 THz heterodyne receiver

abstract:
  The THz atmospheric windows centered at roughly 1.3 and 1.5~THz, contain
numerous spectral lines of astronomical importance, including three high-J CO
lines, the N+ line at 205 microns, and the ground transition of para-H2D+. The
CO lines are tracers of hot (several 100K), dense gas; N+ is a cooling line of
diffuse, ionized gas; the H2D+ line is a non-depleting tracer of cold (~20K),
dense gas. As the THz lines benefit the study of diverse phenomena (from
high-mass star-forming regions to the WIM to cold prestellar cores), we have
built the CO N+ Deuterium Observations Receiver (CONDOR) to further explore the
THz windows by ground-based observations. CONDOR was designed to be used at the
Atacama Pathfinder EXperiment (APEX) and Stratospheric Observatory For Infrared
Astronomy (SOFIA). CONDOR was installed at the APEX telescope and test
observations were made to characterize the instrument. The combination of
CONDOR on APEX successfully detected THz radiation from astronomical sources.
CONDOR operated with typical Trec=1600K and spectral Allan variance times of
30s. CONDOR's first light observations of CO 13-12 emission from the hot core
Orion FIR4 (= OMC1 South) revealed a narrow line with T(MB) = 210K and
delta(V)=5.4km/s. A search for N+ emission from the ionization front of the
Orion Bar resulted in a non-detection. The successful deployment of CONDOR at
APEX demonstrates the potential for making observations at THz frequencies from
ground-based facilities.


title:
Chaotic motion and spiral structure in self-consistent models of
  rotating galaxies

abstract:
  Dissipationless N-body models of rotating galaxies, iso-energetic to a
non-rotating model, are examined as regards the mass in regular and in chaotic
motion. The values of their spin parameters $\lambda$ are near the value
$\lambda=0.22$ of our Galaxy.
  We obtain the distinction between the sets of particles moving in regular and
in chaotic orbits and we show that the spatial distribution of these two sets
of particles is much different. The rotating models are characterized by larger
fractions of mass in chaotic motion ($\thickapprox 65%$) compared with the
fraction of mass in chaotic motion in the non-rotating iso-energetic model
($\thickapprox 32%$). Furthermore, the Lyapunov numbers of the chaotic orbits
in the rotating models become by about one order of magnitude larger than in
the non-rotating model. Chaotic orbits are concentrated preferably in values of
the Jacobi integral around the value of the effective potential at the
corotation radius.
  We find that density waves form a central rotating bar embedded in a thin and
a thick disc with exponential surface density profile. A surprising new result
is that long living spiral arms are exited on the disc, composed almost
completely by chaotic orbits.
  The bar excites an $m=2$ mode of spiral waves on the surface density of the
disc, emanating from the corotation radius. These spiral waves are deformed,
fade, or disappear temporarily, but they grow again re-forming a well developed
spiral pattern. Spiral arms are discernible up to 20 or 30 rotations of the bar
(lasting for about a Hubble time).


title:
Modelling the spectral energy distribution of galaxies. IV Correcting
  apparent disk scalelengths and central surface brightnesses for the effect of
  dust at optical and near-infrared wavelengths

abstract:
  We present corrections for the change in the apparent scalelengths, central
surface brightnesses and axis ratios due to the presence of dust in pure disk
galaxies, as a function of inclination, central face-on opacity in the B-band
(tau^f_B) and wavelength. The correction factors were derived from simulated
images of disk galaxies created using geometries for stars and dust which can
reproduce the entire spectral energy distribution from the ultraviolet (UV) to
the Far-infrared (FIR)/submillimeter (submm) and can also account for the
observed surface-brightness distributions in both the optical/Near-infrared and
FIR/submm. We found that dust can significantly affect both the scalelength and
central surface brightness, inducing variations in the apparent to intrinsic
quantities of up to 50 percent in scalelength and up to 1.5 magnitudes in
central surface brightness. We also identified some astrophysical effects for
which, although the absolute effect of dust is non-negligible, the predicted
variation over a likely range in opacity is relatively small, such that an
exact knowledge of opacity is not needed. Thus, for a galaxy at a typical
inclination of 37 degrees and having any tau^f_B>2, the effect of dust is to
increase the scalelength in B relative to that in I by a factor of 1.12 +- 0.02
and to change the B-I central colour by 0.36 +- 0.05 magnitudes. Finally we use
the model to analyse the observed scalelength ratios between B and I for a
sample of disk-dominated spiral galaxies, finding that the tendency for
apparent scalelength to increase with decreasing wavelength is primarily due to
the effects of dust.


title:
First Fruits of the Spitzer Space Telescope: Galactic and Solar System
  Studies

abstract:
  This article provides a brief overview of the Spitzer Space Telescope and
discusses its initial scientific results on galactic and solar system science.


title: One-dimensional Hybrid Approach to Extensive Air Shower Simulation

abstract:
  An efficient scheme for one-dimensional extensive air shower simulation and
its implementation in the program CONEX are presented. Explicit Monte Carlo
simulation of the high-energy part of hadronic and electromagnetic cascades in
the atmosphere is combined with a numeric solution of cascade equations for
smaller energy sub-showers to obtain accurate shower predictions. The developed
scheme allows us to calculate not only observables related to the number of
particles (shower size) but also ionization energy deposit profiles which are
needed for the interpretation of data of experiments employing the fluorescence
light technique. We discuss in detail the basic algorithms developed and
illustrate the power of the method. It is shown that Monte Carlo, numerical,
and hybrid air shower calculations give consistent results which agree very
well with those obtained within the CORSIKA program.


title: Thermal Emission from a Hot Cocoon Surrounding the Jet of XRF 060218

abstract:
  It is long speculated that long duration gamma-ray bursts (GRBs) originate
froma relativistic jet emerging from a collapsing massive star progenitor.
Although associations of core-collapsing supernovae with long GRB afterglows
have been identified in a number of systems, including the latest X-ray flash
(XRF) 060218/SN 2006aj connection detected by Swift, direct evidence of a
relativistic jet emerging from a collapsing star is still lacking. Here we
report the detection of a thermal emission component (high-T component)
accompanying the prompt X-ray emission of XRF 060218, with temperature
kT_H=1.21+0.22/-0.24 keV and effective blackbody radius R_H~ 5\times 10^{9} cm.
This high-T component co-exists with another low-T thermal component as
reported by Campana et al. 2006 for at least 2700 seconds, but evolves
independently with respect to the low-T component by tracing the lightcurve of
the non-thermal component. We identify this high-T thermal component as the
emission of a hot cocoon surrounding the relativistic jet, as expected from the
theoretical models.


title: Galilean Equivalence for Galactic Dark Matter

abstract:
  Satellite galaxies are tidally disrupted as they orbit the Milky Way. If dark
matter (DM) experiences a stronger self-attraction than baryons, stars will
preferentially gain rather than lose energy during tidal disruption leading to
an enhancement in the trailing compared to the leading tidal stream. The Sgr
dwarf galaxy is seen to have roughly equal streams, challenging models in which
DM and baryons accelerate differently by more than 10%. Future observations and
a better understanding of DM distribution should allow detection of equivalence
violation at the percent level.


title:
The prompt optical/near-infrared flare of GRB 050904: the most luminous
  transient ever detected

abstract:
  With a redshift of z=6.295, GRB 050904 is the most distant gamma-ray burst
ever discovered. It was an energetic event at all wavelengths and the afterglow
was observed in detail in the near-infrared bands. We gathered all available
optical and NIR afterglow photometry of this GRB to construct a composite NIR
light curve spanning several decades in time and flux density. Transforming the
NIR light curve into the optical, we find that the afterglow of GRB 050904 was
more luminous at early times than any other GRB afterglow in the
pre-\emph{Swift} era, making it at these wavelengths the most luminous
transient ever detected. Given the intrinsic properties of GRB 050904 and its
afterglow, we discuss if this burst is markedly different from other GRBs at
lower redshifts.


title: Measuring dark energy properties with 3D cosmic shear

abstract:
  We present parameter estimation forecasts for present and future 3D cosmic
shear surveys. We demonstrate that, in conjunction with results from cosmic
microwave background (CMB) experiments, the properties of dark energy can be
estimated with very high precision with large-scale, fully 3D weak lensing
surveys. In particular, a 5-band, 10,000 square degree ground-based survey to a
median redshift of zm=0.7 could achieve 1-$\sigma$ marginal statistical errors,
in combination with the constraints expected from the CMB Planck Surveyor, of
$\Delta$w0=0.108 and $\Delta$wa=0.099 where we parameterize w by
w(a)=w0+wa(1-a) where a is the scale factor. Such a survey is achievable with a
wide-field camera on a 4 metre class telescope. The error on the value of w at
an intermediate pivot redshift of z=0.368 is constrained to
$\Delta$w(z=0.368)=0.0175. We compare and combine the 3D weak lensing
constraints with the cosmological and dark energy parameters measured from
planned Baryon Acoustic Oscillation (BAO) and supernova Type Ia experiments,
and find that 3D weak lensing significantly improves the marginalized errors. A
combination of 3D weak lensing, CMB and BAO experiments could achieve
$\Delta$w0=0.037 and $\Delta$wa=0.099. Fully 3D weak shear analysis avoids the
loss of information inherent in tomographic binning, and we show that the
sensitivity to systematic errors is much less. In conjunction with the fact
that the physics of lensing is very soundly based, this analysis demonstrates
that deep, wide-angle 3D weak lensing surveys are extremely promising for
measuring dark energy properties.


title: Viscosity driven instability in rotating relativistic stars

abstract:
  We investigate the viscosity driven instability in rotating relativistic
stars by means of an iterative approach. We focus on polytropic rotating
equilibrium stars and impose an m=2 perturbationin the lapse. We vary both the
stiffness of the equation of state and the compactness of the star to study
those effects on the value of the threshold. For a uniformly rotating star, the
criterion T/W, where T is the rotational kinetic energy and W is the
gravitational binding energy, mainly depends on the compactness of the star and
takes values around 0.13 ~ 0.16, which differ slightly from that of Newtonian
incompressible stars (~ 0.14). For differentially rotating stars, the critical
value of T/W is found to span the range 0.17 - 0.25. This is significantly
larger than the uniformly rotating case with the same compactness of the star.
Finally we discuss a possibility of detecting gravitational waves from
viscosity driven instability with ground-based interferometers.


title: Is There a Fundamental Line for Disk Galaxies?

abstract:
  We show that there are strong local correlations between metallicity, surface
brightness, and dynamical mass-to-light ratio within M33, analogous to the
fundamental line of dwarf galaxies identified by Prada & Burkert (2002). Using
near-infrared imaging from 2MASS, the published rotation curve of M33, and
literature measurements of the metallicities of HII regions and supergiant
stars, we demonstrate that these correlations hold for points at radial
distances between 140 pc and 6.2 kpc from the center of the galaxy. At a given
metallicity or surface brightness, M33 has a mass-to-light ratio approximately
four times as large as the Local Group dwarf galaxies; other than this constant
offset, we see broad agreement between the M33 and dwarf galaxy data. We use
analytical arguments to show that at least two of the three fundamental line
correlations are basic properties of disk galaxies that can be derived from
very general assumptions. We investigate the effect of supernova feedback on
the fundamental line with numerical models and conclude that while feedback
clearly controls the scatter in the fundamental line, it is not needed to
create the fundamental line itself, in agreement with our analytical
calculations. We also compare the M33 data with measurements of a simulated
disk galaxy, finding that the simulation reproduces the trends in the data
correctly and matches the fundamental line, although the metallicity of the
simulated galaxy is too high, and the surface brightness is lower than that of
M33.


title: GaBoDS: The Garching-Bonn Deep Survey: VI. Cosmic shear analysis

abstract:
  Aims. We present a cosmic shear analysis and data validation of 15 square
degree high-quality R-band data of the Garching-Bonn Deep Survey obtained with
the Wide Field Imager of the MPG/ESO 2.2m telescope. Methods. We measure the
two-point shear correlation functions to calculate the aperture mass
dispersion. Both statistics are used to perform the data quality control.
Combining the cosmic shear signal with a photometric redshift distribution of a
galaxy sub-sample obtained from two square degree of UBVRI-band observations of
the Deep Public Survey we determine constraints for the matter density Omega_m,
the mass power spectrum normalisation sigma_8 and the dark energy density
Omega_Lambda in the magnitude interval R in [21.5,24.5]. In this magnitude
interval the effective number density of source galaxies is n=12.5/sq. arcmin,
and their mean redshift is z_m=0.78. To estimate the posterior likelihood we
employ the Monte Carlo Markov Chain method. Results. Using the aperture mass
dispersion we obtain for the mass power spectrum normalisation sigma_8=0.80 +-
0.10 (1 sigma statistical error) at a fixed matter density Omega_m=0.30
assuming a flat universe with negligible baryon content and marginalising over
the Hubble parameter and the uncertainties in the fitted redshift distribution.


title: Thermal Evaporation of Gas from X-ray Clusters

abstract:
  A fraction of the thermal protons in the outer envelope of an X-ray cluster
have velocities that exceed the local escape speed from the cluster
gravitational potential. The Coulomb mean-free-path of these protons is larger
than the virial radius of the cluster at temperatures >2.5 keV. The resulting
leakage of suprathermal particles generates a collisionless shock in
neighboring voids and fills them with heat and magnetic fields. The momentum
flux of suprathermal particles cannot be confined by magnetic tension at the
typical field strength in the periphery of cluster halos (<<1 micro-gauss).
Over a Hubble time, thermal evaporation could drain up to a tenth of the
cluster gas at its virial temperature. The evaporated fraction could increase
dramatically if additional heat is deposited into the gas by cluster mergers,
active galactic nuclei or supernovae. Thermal evaporation is not included in
existing cosmological simulations since they are based on the fluid
approximation. Measurements of the baryon mass fraction in the outer envelopes
of hot clusters (through their Sunyaev-Zel'dovich effect or X-ray emission) can
be used to empirically constrain their evaporation rate.


title: Super-Solar Super Lyman Limit Systems

abstract:
  We present abundance measurements for two super Lyman Limit systems (SLLS;
quasar absorption line systems with 10^19 cm^-2 < N_HI < 10^20.3 cm^-2)
selected from a set of metal-strong absorbers in the Sloan Digital Sky Survey
quasar database. After applying estimate corrections for photoionization
effects, we derive gas-phase metallicities of [M/H]=+0.7 +/- 0.2 dex for the
SLLS at z=1.7749 toward SDSS0927+5621 and [M/H]=+0.05 +/- 0.1 dex for the SLLS
at z=1.7678 toward SDSS0953+5230. The former exhibits among the highest gas
metallicity of any astrophysical environment and its total metal surface
density exceeds that of nearly every known damped Lya system. The properties of
these absorbers -- high metallicity and large velocity width (> 300 km/s) --
resemble those of gas observed in absorption in the spectra of bright,
star-forming galaxies at high redshift. We discuss the metal mass density of
the SLLS based on these observations and our ongoing SLLS survey and argue that
a conservative estimate to the total metal budget at z=2 is greater than 15% of
the total, suggesting that the metal-rich LLS may represent the dominant metal
reservoir in the young universe.


title: Future state of the Universe

abstract:
  Following the observational evidence for cosmic acceleration which may
exclude a possibility for the universe to recollapse to a second singularity,
we review alternative scenarios of its future evolution. Although the de Sitter
asymptotic state is still an option, some other asymptotic states which allow
new types of singularities such as Big-Rip (due to a phantom matter) and sudden
future singularities are also admissible and are reviewed in detail. The
reality of these singularities which comes from the relation to observational
characteristics of the universe expansion are also revealed and widely
discussed.


title: Neutrino-Accelerated Hot Hydrogen Burning

abstract:
  We examine the effects of significant electron anti-neutrino fluxes on
hydrogen burning. Specifically, we find that the bottleneck weak nuclear
reactions in the traditional pp-chain and the hot CNO cycle can be accelerated
by anti-neutrino capture, increasing the energy generation rate. We also
discuss how anti-neutrino capture reactions can alter the conditions for break
out into the rp-process. We speculate on the impact of these considerations for
the evolution and dynamics of collapsing very- and super- massive compact
objects.


title: The compact circumstellar material around OH 231.8+4.2

abstract:
  We have observed the bipolar post-AGB candidate OH 231.8+4.2, using the
mid-infrared interferometer MIDI and the infrared camera with the adaptive
optics system NACO on the Very Large Telescope. An unresolved core (<200 mas in
FWHM) is found at the center of the OH 231.8+4.2 in the 3.8 micron image. This
compact source is resolved with the interferometer. We used two 8-meter
telescopes with four different baselines, which cover projected baseline
lengths from 62 to 47 meters, and projected position angles from 112 to 131
degrees that are almost perpendicular to the bipolar outflow. Fringes from 8 to
9 micron and from 12 to 13.5 micron were clearly detected, whilst the strong
silicate self-absorption allows only marginal detection of visibilities between
9 and 12 micron. The fringes from the four baselines consistently show the
presence of a compact circumstellar object with an inner radius of 30-40 mas,
which is equivalent to 40-50 AU at 1.3 kpc. This clearly shows that the
mid-infrared compact source is not the central star (3 AU) but circumstellar
material. The measured size of the circumstellar material is consistent with
the size of such disks calculated by hydrodynamic models, implying the
circumstellar material may have a disk configuration.


title:
Modelling the closest double degenerate system RXJ0806.3+1527 and its
  decreasing period

abstract:
  In the hypothesis that the 5.4m binary RXJ0806.3+1527 consists of a low mass
helium white dwarf (donor) transferring mass towards its more massive white
dwarf companion (primary), we consider as possible donors white dwarfs which
are the result of common envelope evolution occurring when the helium core mass
of the progenitor giant was still very small (~ 0.2Msun), so that they are
surrounded by a quite massive hydrogen envelope (~1/100Msun or larger), and
live for a very long time supported by proton--proton burning. Mass transfer
from such low mass white dwarfs very probably starts during the hydrogen
burning stage, and the donor structure will remain dominated by the burning
shell until it loses all the hydrogen envelope and begins transferring helium.
We model mass transfer from these low mass white dwarfs, and show that the
radius of the donor decreases while they shed the hydrogen envelope. This
radius behavior, which is due to the fact that the white dwarf is not fully
degenerate, has two important consequences on the evolution of the binary: 1)
the orbital period decreases, with a timescale consistent with the period
decrease of the binary RXJ0806.3+1527; 2) the mass transfer rate is a factor of
about 10 smaller than from a fully degenerate white dwarf, easing the problem
connected with the small X-ray luminosity of this object. The possibility that
such evolution describes the system RXJ0806.3+1527 is also consistent with the
possible presence of hydrogen in the optical spectrum of the star, whose
confirmation would become a test of the model.


title:
GaBoDS: The Garching-Bonn Deep Survey VIII. Lyman-break galaxies in the
  ESO Deep Public Survey

abstract:
  Aims. The clustering properties of a large sample of U-dropouts are
investigated and compared to very precise results for B-dropouts from other
studies to identify a possible evolution from z=4 to z=3. Methods. A population
of ~8800 candidates for star-forming galaxies at z=3 is selected via the
well-known Lyman-break technique from a large optical multicolour survey (the
ESO Deep Public Survey). The selection efficiency, contamination rate, and
redshift distribution of this population are investigated by means of extensive
simulations. Photometric redshifts are estimated for every Lyman-break galaxy
(LBG) candidate from its UBVRI photometry yielding an empirical redshift
distribution. The measured angular correlation function is deprojected and the
resulting spatial correlation lengths and slopes of the correlation function of
different subsamples are compared to previous studies. Results. By fitting a
simple power law to the correlation function we do not see an evolution in the
correlation length and the slope from other studies at z=4 to our study at z=3.
In particular, the dependence of the slope on UV-luminosity similar to that
recently detected for a sample of B-dropouts is confirmed also for our
U-dropouts. For the first time number statistics for U-dropouts are sufficient
to clearly detect a departure from a pure power law on small scales down to ~2"
reported by other groups for B-dropouts.


title: Interloper treatment in dynamical modelling of galaxy clusters

abstract:
  The aim of this paper is to study the efficiency of different approaches to
interloper treatment in dynamical modelling of galaxy clusters. Using
cosmological N-body simulation of standard LCDM model, we select 10 massive
dark matter haloes and use their particles to emulate mock kinematic data in
terms of projected galaxy positions and velocities as they would be measured by
a distant observer. Taking advantage of the full 3D information available from
the simulation, we select samples of interlopers defined with different
criteria. The interlopers thus selected provide means to assess the efficiency
of different interloper removal schemes found in the literature. We study
direct methods of interloper removal based on dynamical or statistical
restrictions imposed on ranges of positions and velocities available to cluster
members. In determining these ranges, we use either the velocity dispersion
criterion or a maximum velocity profile. We also generalize the common
approaches taking into account both the position and velocity information.
Another criterion is based on the dependence of the commonly used virial mass
and projected mass estimators on the presence of interlopers. We find that the
direct methods exclude on average 60-70 percent of unbound particles producing
a sample with contamination as low as 2-4 percent. Next, we consider indirect
methods of interloper treatment which are applied to the data stacked from many
objects. In these approaches, interlopers are treated in a statistical way as a
uniform background which modifies the distribution of cluster members. Using a
Bayesian approach, we reproduce the properties of composite clusters and
estimate the probability of finding an interloper as a function of distance
from the object centre.


title: Metallicity Dependent Wolf-Rayet Winds

abstract:
  Observational and theoretical evidence in support of metallicity dependent
winds for Wolf-Rayet stars is considered. Well known differences in Wolf-Rayet
subtype distributions in the Milky Way, LMC and SMC may be attributed to the
sensitivity of subtypes to wind density. Implications for Wolf-Rayet stars at
low metallicity include a hardening of ionizing flux distributions, an
increased WR population due to reduced optical line fluxes, plus support for
the role of single WR stars as Gamma Ray Burst progenitors.


title:
Stability of the Accretion Flows with Stalled Shocks in Core-Collapse
  Supernovae

abstract:
  Bearing in mind the application to the theory of core-collapse supernovae, we
performed a global linear analysis on the stability of spherically symmetric
accretion flows through a standing shock wave onto a proto neutron star. As
unperturbed flows, we adopted the spherically symmetric steady solutions to the
Euler equations obtained with realistic equation of state and formulae for
neutrino reaction rates taken into account. Then we solved the equations for
linear perturbations numerically, and obtained the eigen frequencies and eigen
functions. We found (1) the flows are stable for all modes if the neutrino
luminosity is lower than $\sim 1\times 10^{52}$ ergs/s for
$\dot{M}=1.0M_{\odot}/{\rm s}$. (2) For larger luminosities, the non-radial
instabilities are induced, probably via the advection-acoustic cycles.
Interestingly, the modes with $\ell=2$ and 3 become unstable at first for
relatively low neutrino luminosities, e.g. $\gtrsim 2-3\times 10^{52}$ ergs/s
for the same accretion rate, whereas the $\ell=1$ mode is the most unstable for
higher luminosities, $\sim 3-7\times 10^{52}$ ergs/s. These are all oscillatory
modes. (3) For still larger luminosities, $\sim 7\times 10^{52}$ ergs/s for
$\dot{M}=1.0M_{\odot}/{\rm s}$, non-oscillatory modes, both radial and
non-radial, become unstable. These non-radial modes were identified as
convection. We confirmed the results obtained by numerical simulations that the
instabilities induced by the advection-acoustic cycles are more important than
the convection for lower neutrino luminosities.


title:
The Star-Forming Region NGC 346 in the Small Magellanic Cloud with
  Hubble Space Telescope ACS Observations I. Photometry

abstract:
  We present a photometric study of the star-forming region NGC 346 and its
surrounding field in the Small Magellanic Cloud, using data taken with the
Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST).
The data set contains both short and long exposures for increased dynamic
range, and photometry was performed using the ACS module of the stellar
photometry package DOLPHOT. We detected almost 100,000 stars over a magnitude
range of V ~ 11 to V ~ 28 mag, including all stellar types from the most
massive young stars to faint lower main sequence and pre-main sequence stars.
We find that this region, which is characterized by a plethora of stellar
systems and interesting objects, is an outstanding example of mixed stellar
populations. We take into account different features of the color-magnitude
diagram of all the detected stars to distinguish the two dominant stellar
systems: The stellar association NGC 346 and the old spherical star cluster BS
90. These observations provide a complete stellar sample of a field about 5
arcmin x 5 arcmin around the most active star-forming region in this galaxy.
Considering the importance of these data for various investigations in the
area, we provide the full stellar catalog from our photometry. This paper is
the first part of an ongoing study to investigate in detail the two dominant
stellar systems in the area and their surrounding field.


title: Grand Challenges in Planetary Nebulae Studies: Binary Evolution and MHD

abstract:
  We review work on the evolution of planetary nebulae and proto-planetaries
via magneto-rotational mechanisms showing that a dynamo generated magnetic
field can produce the energy and momentum needed to drive pPN and PNe outflows.
Angular momentum considerations lead to the conclusion that single stars may
not be capable of supporting strong fields for long times. Thus we take the
working hypothesis that most PN may form via binary stars. We propose that the
grand challenge for PN studies is fully understanding the diverse physical
processes at work in binary late stage evolution including the development of
disks, fields and outflows.


title: No-go theorem for k-essence dark energy

abstract:
  We demonstrate that if k-essence can solve the coincidence problem and play
the role of dark energy in the universe, the fluctuations of the field have to
propagate superluminally at some stage. We argue that this implies that
successful k-essence models violate causality. It is not possible to define a
time ordered succession of events in a Lorentz invariant way. Therefore,
k-essence cannot arise as low energy effective field theory of a causal,
consistent high energy theory.


title:
Integral field spectroscopy of the Luminous Infrared Galaxy Arp299
  (IC694+NGC3690)

abstract:
  The luminous infrared galaxy Arp299 (IC694+NGC3690) is studied using optical
integral field spectroscopy obtained with the INTEGRAL system, together with
archival Hubble Space Telescope WFPC2 and NICMOS images. The stellar and
ionized gas morphology shows lambda-dependent variations due to the combined
effects of the dust internal extinction, and the nature and spatial
distribution of the different ionizing sources. The two-dimensional ionization
maps have revealed an off-nuclear conical structure of about 4 kpc in length,
characterized by high excitation conditions and a radial gradient in the gas
electron density. The apex of this structure coincides with B1 region of
NGC3690 which, in turn, presents Seyfert-like ionization, high extinction and a
high velocity dispersion. These results strongly support the hypothesis that B1
is the true nucleus of NGC3690, where an AGN is located. In the circumnuclear
regions HII-like ionization dominates, while LINER-like ionization is found
elsewhere. The Halpha emitting sources with ages from 3.3 to 7.2x10^6 years,
have masses of between 6 and 680x10^6 Msun and contribute (extinction
corrected) about 45% to the bolometric luminosity. The ionized (Halpha) and
neutral (NaD) gas velocity fields show similar structure on scales of several
hundred to about 1 kpc, indicating that these gas components are kinematically
coupled. The kinematic structure is complex and on scales of about 0.2 kpc does
not appear to be dominated by the presence of ordered, rotational motions. The
large velocity dispersion measured in NGC3690 indicates that this galaxy is the
most massive of the system. The low velocity amplitude and dispersion of the
interface suggest that the ionized gas is slowly rotating or in a close to
quiescent phase.


title:
Formation of Galactic Systems in Light of the Magnesium Abundance in
  Field Stars.III.the Halo

abstract:
  We analyze the relations between the relative magnesium abundances,
metallicities, and Galactic orbital elements for halo stars. We show that the
relative magnesium abundances in protodisk halo stars are virtually independent
of metallicity and lie within a fairly narrow range while presumably accreted
stars demonstrate a large spread in relative magnesium abundances up to
negative [Mg/Fe]. The mean metallicity of magnesium-poor ([Mg/Fe]<0.2 dex)
accreted stars has been found to be displaced toward the negative values when
passing from stars with low azimuthal velocities to those with high ones at
\Delta[Fe/H]=0.5dex. The mean apogalactic radii and inclinations of the orbits
also increase while their eccentricities decrease. As a result negative radial
and vertical gradients in relative magnesium abundances are observed in the
accreted halo in the absence of correlations between the [Mg/Fe] ratios and
other orbital elements, while these correlations are found at a high
significance level for genetically related Galactic stars. We surmise that as
the masses of dwarf galaxies decrease, the maximum SNII masses and hence, the
yield of \alpha-elements in them also decrease. In this case, the relation
between the [Mg/Fe] ratios and the inclinations and sizes of the orbits of
accreted stars is in complete agreement with numerical simulations of dynamical
processes during the interaction of galaxies. Thus the behavior of the
magnesium abundance in accreted stars suggests that the satellite galaxies are
disrupted and lose their stars en masse only after dynamical friction reduces
significantly the sizes of their orbits and drags them into the Galactic plane.
Less massive satellite galaxies are disrupted even before their orbits change
appreciably under tidal forces.


title: UBVJHK synthetic photometry of Galactic O stars

abstract:
  The development of powerful infrared observational technics enables the study
of very extincted objects and young embedded star forming regions. This is
especially interesting in the context of massive stars which form and spend a
non negligible fraction of their life still enshrouded in their parental
molecular cloud. Spectrophotometric calibrations are thus necessary to
constrain the physical properties of heavily extincted objects. Here, we derive
UBVJHK magnitudes and bolometric corrections from a grid of atmosphere models
for O stars. Bessel passbands are used. Bolometric corrections (BC) are derived
as a function of Teff and are subsequently used to derive BC - spectral type
(ST) and Absolute Magnitudes - ST relations. Infrared magnitudes and, for the
first time, bolometric corrections are given for the full range of spectral
types and luminosity classes. Infrared colors are essentially constant.
Intrinsic H-K colors are 0.05 mag bluer than previously proposed. Optical
calibrations are also provided and are similar to previous work, except for
(B-V)0 which is found to be at minimum -0.28 for standard O stars, slightly
larger (0.04 mag) than commonly accepted.


title: Detecting a rotation in the epsilon Eridani debris disc

abstract:
  The evidence for a rotation of the epsilon Eridani debris disc is examined.
Data at 850 micron wavelength were previously obtained using the Submillimetre
Common User Bolometer Array (SCUBA) over periods in 1997-1998 and 2000-2002. By
chi-square fitting after shift and rotation operations, images from these two
epochs were compared to recover proper motion and orbital motion of the disc.
The same procedures were then performed on simulated images to estimate the
accuracy of the results.
  Minima in the chi-square plots indicate a motion of the disc of approximately
0.6'' per year in the direction of the star's proper motion. This
underestimates the true value of 1'' per year, implying that some of the
structure in the disc region is not associated with epsilon Eridani,
originating instead from background galaxies. From the chi-square fitting for
orbital motion, a counterclockwise rotation rate of ~2.75 degrees per year is
deduced. Comparisons with simulated data in which the disc is not rotating show
that noise and background galaxies result in approximately Gaussian
fluctuations with a standard deviation +/-1.5 degrees per year. Thus
counterclockwise rotation of disc features is supported at approximately a
2-sigma level, after a 4-year time difference. This rate is faster than the
Keplerian rate of 0.65 degrees per year for features at ~65 AU from the star,
suggesting their motion is tracking a planet inside the dust ring.
  Future observations with SCUBA-2 can rule out no rotation of the epsilon
Eridani dust clumps with ~4-sigma confidence. Assuming a rate of about 2.75
degrees per year, the rotation of the features after a 10-year period could be
shown to be >1 degree per year at the 3-sigma level.


title: An optimum time-stepping scheme for N-body simulations

abstract:
  We present a new time-stepping criterion for N-body simulations that is based
on the true dynamical time of a particle. This allows us to follow the orbits
of particles correctly in all environments since it has better adaptivity than
previous time-stepping criteria used in N-body simulations. Furthermore, it
requires far fewer force evaluations in low density regions of the simulation
and has no dependence on artificial parameters such as, for example, the
softening length. This can be orders of magnitude faster than conventional
ad-hoc methods that employ combinations of acceleration and softening and is
ideally suited for hard problems, such as obtaining the correct dynamics in the
very central regions of dark matter haloes. We also derive an eccentricity
correction for a general leapfrog integration scheme that can follow
gravitational scattering events for orbits with eccentricity e -> 1 with high
precision. These new approaches allow us to study a range of problems in
collisionless and collisional dynamics from few body problems to cosmological
structure formation. We present tests of the time-stepping scheme in N-body
simulations of 2-body orbits with eccentricity e -> 1 (elliptic and
hyperbolic), equilibrium haloes and a hierarchical cosmological structure
formation run.


title:
A Time Dependent Leptonic Model for Microquasar Jets: Application to LSI
  61 303

abstract:
  The Galactic high-mass X-ray binary and jet source (microquasar) LSI +61 303
has recently been detected at TeV gamma-ray energies by the MAGIC telescope. We
have applied a time-dependent leptonic jet model to the broadband spectral
energy distribution and suggested (though not unambiguously detected) orbital
modulation of the very high energy gamma-ray emission of this source. Our model
takes into account time dependent electron injection and acceleration, and the
adiabatic and radiative cooling of non-thermal electrons. It includes
synchrotron, synchrotron self-Compton and external inverse Compton (with seed
photons from the companion star), as well as gamma-gamma absorption of
gamma-rays by starlight photons. The model can successfully reproduce the
available multiwavelength observational data. Our best fit to the SED indicates
that a magnetic field of B_0 ~ 5 X 10^3 G at ~ 10^3 R_g is required, and
electrons need to be accelerated out to TeV energies (gamma_2 = 10^6) with a
nonthermal injection spectrum with a spectral index of q = 1.7, indicating the
operation of acceleration mechanisms beyond the standard first-order Fermi
mechanism at relativistic or non-relativistic shocks. The orbital modulation of
the VHE gamma-ray emission can be explained solely by the geometrical effect of
changes in the relative orientation of the stellar companion with respect to
the compact object and jet as it impacts the position and depth of the
gamma-gamma absorption trough. Such a scenario predicts a trend of spectral
hardening during VHE gamma-ray low orbital phases.


title: Clusters and Groups of Galaxies in the Simulated Local Universe

abstract:
  We compare the properties of galaxy groups extracted from the Updated Zwicky
Catalogue (UZC) with those of groups extracted from N-body simulations of the
local Universe, in a LambdaCDM and a tauCDM cosmology. In the simulations, the
initial conditions of the dark matter density field are set to reproduce the
present time distribution of the galaxies within 80 Mpc/h from the Milky Way.
These initial conditions minimize the uncertainty originated by cosmic
variance, which has affected previous analyses of this small volume of the
Universe. The simulations also model the evolution of the photometric
properties of the galaxy population with semi-analytic prescriptions. The
models yield a galaxy luminosity function sensibly different from that of the
UZC and are unable to reproduce the distribution of groups and their luminosity
content. The discrepancy between the model and the UZC reduces substantially,
if we redistribute the luminosity among the galaxies in the simulation
according to the UZC luminosity function while preserving the galaxy luminosity
rank. The modified LambdaCDM model provides the best match to the UZC: the
abundances of groups by harmonic radius, velocity dispersion, mass and
luminosity are consistent with observations. We find that this model also
reproduces the halo occupation number of groups and clusters. However, the
large-scale distribution of groups is marginally consistent with the UZC and
the redshift-space correlation function of galaxies on scales larger than 6
Mpc/h is still more than 3-sigma smaller than observed. We conclude that
reproducing the properties of the observed groups certainly requires a more
sophisticated treatment of galaxy formation, and possibly an improvement of the
dark matter model.


title:
Non linear particle acceleration at non-relativistic shock waves in the
  presence of self-generated turbulence

abstract:
  Particle acceleration at astrophysical shocks may be very efficient if
magnetic scattering is self-generated by the same particles. This nonlinear
process adds to the nonlinear modification of the shock due to the dynamical
reaction of the accelerated particles on the shock. Building on a previous
general solution of the problem of particle acceleration with arbitrary
diffusion coefficients (Amato & Blasi, 2005), we present here the first
semi-analytical calculation of particle acceleration with both effects taken
into account at the same time: charged particles are accelerated in the
background of Alfven waves that they generate due to the streaming instability,
and modify the dynamics of the plasma in the shock vicinity.


title: Asymmetric Spatiotemporal Evolution of Prebiotic Homochirality

abstract:
  The role of asymmetry on the evolution of prebiotic homochirality is
investigated in the context of autocatalytic polymerization reaction networks.
A model featuring enantiometric cross-inhibition and chiral bias is used to
study the diffusion equations controlling the spatiotemporal development of
left and right-handed domains. Bounds on the chiral bias are obtained
consistent with present-day constraints on the emergence of life on early
Earth. The viability of biasing mechanisms such as weak neutral currents and
circularly polarized UV light is discussed. The results can be applied to any
hypothetical planetary platform.

categories: astro-ph cond-mat.stat-mech physics.bio-ph physics.chem-ph q-bio.BM


title:
Fe-bump instability: the excitation of pulsations in subdwarf B and
  other low-mass stars

abstract:
  We consider the excitation of radial and non-radial oscillations in low-mass
B stars by the iron-bump opacity mechanism. The results are significant for the
interpretation of pulsations in subdwarf B stars, helium-rich subdwarfs and
extreme helium stars, including the EC14026 and PG1716 variables. We
demonstrate that, for radial oscillations, the driving mechanism becomes
effective by increasing the contrast between the iron-bump opacity and the
opacity from other sources. The location of the iron-bump instability boundary
depends on the mean molecular weight in the envelope and also on the radial
order of the oscillation. A bluer instability boundary is provided by
increasing the iron abundance alone, explaining the observed EC14026 variables,
and by higher radial order oscillations. We show that the coolest EC14026
variables may vary in the fundamental radial mode, but the hottest variables
must be of higher radial order. In considering non-radial oscillations, we
demonstrate that g-modes of high radial order and low spherical degree (l<4)
may be excited in some blue horizontal branch stars with near-normal
composition (Z=0.02). Additional iron enhancement extends the g-mode
instability zone to higher effective temperatures and also creates a p-mode
instability zone. With sufficient iron, the p-mode and g-mode instability zones
overlap, allowing a small region where the EC14026 and PG1716-type variability
can be excited simultaneously. However its location is roughly 5000 K too low
compared with the observed boundary between EC14026 and PG1716 variables.


title: A catalogue of micro-Jy radio sources in northern legacy fields

abstract:
  We present catalogues of faint 1.4-GHz radio sources from extremely-deep Very
Large Array pointings in the Lockman Hole, the Hubble Deep Field North (HDF-N)
and ELAIS N2. Our analysis of the HDF-N data has produced maps that are
significantly deeper than those previously published and we have used these to
search for counterparts to submm sources. For each of the fields we have
derived normalised differential source counts and in the case of the HDF-N find
no evidence for the previously-reported under-density of sources; our counts
are entirely consistent with those found for the majority of other fields. The
catalogues are available as an online supplement to this paper and the maps are
also available for download.


title:
A search for a counterpart of the unidentified gamma-ray source 3EG
  J2020+4017 (2CG078+2)

abstract:
  We report observations with the Chandra X-ray Observatory of a field in the
gamma$-Cygni supernova remnant (SNR78.2+2.1) centered on the cataloged location
of the unidentified, bright gamma-ray source 3EG J2020+4017. In this search for
an X-ray counterpart to the gamma-ray source, we detected 30 X-ray sources. Of
these, we found 17 strong-candidate counterparts in optical (visible through
near-infrared) cataloged and an additional 3 through our optical observations.
Based upon colors and (for several objects) optical spectra, nearly all the
optically identified objects appear to be reddened main-sequence stars. None of
the X-ray sources with an optical counterpart is a plausible X-ray counterpart
to 3EG J2020+4017 --if that gamma-ray source is a spin-powered pulsar. Many of
the 10 X-ray sources lacking optical counterparts are likely (extragalactic)
active galactic nuclei, based upon the sky density of such sources. Although
one of the 10 optically unidentified X-ray sources could be the gamma-ray
source, there is no auxiliary evidence supporting such an identification.


title: The Integral Field Spectrograph of SPHERE: the Planet Finder for VLT

abstract:
  SPHERE is an instrument designed and built by a consortium of French, German,
Italian, Swiss and Dutch institutes in collaboration with ESO. The project is
currently in its Phase B. The main goal of SPHERE is to gain at least one order
of magnitude with respect to the present VLT AO facility (NACO) in the direct
detection of faint objects very close to a bright star, especially giant
extrasolar planets. Apart from a high Strehl ratio, the instrument will be
designed to reduce the scattered light of the central bright star and subtract
the residual speckle halo. Sophisticated post-AO capabilities are needed to
provide maximum detectivity and possibly physical data on the putative planets.
The Integral Field Spectrograph (IFS), one of the three scientific channels
foreseen in the SPHERE design, is a very low resolution spectrograph (R~20)
which works in the near IR (0.95-1.35 micron), an ideal wavelength range for
the ground based detection of planetary features. Its goal is to suppress
speckle to a contrast of 10^7, with a goal of 10^8, and at the same time
provide spectral information in a field of view of about 1.5 x 1.5 arcsecs^2 in
proximity of the target star. In this paper we describe the overall IFS design
concept.


title: Radio Spectrum and Distance of the SNR HB9

abstract:
  New images are presented of the supernova remnant (SNR) HB9 based on 408 MHz
and 1420 MHz continuum emission and HI-line emission data of the Canadian
Galactic Plane Survey (CGPS) by the Dominion Radio Astrophysical Observatory
(DRAO). Two methods of spectral index analysis for HB9 are presented and
compared: one removes compact sources at both frequencies but is limited to the
resolution of the 408 MHz image; the other removes compact sources only in the
1420 MHz image so is effective at higher spatial resolution. The second allows
more detailed spectral index variation studies than the first. The two T-T plot
methods and new integrated flux densities give spectral index
(S_{\nu}\propto\nu^{-alpha}) for the whole of HB9 of 0.48+-0.03; and
0.47+-0.06, respectively. These are lower than previous spectral index for HB9
(alpha=0.61). Spatial variations of spectral index are derived using the second
method and yield a steeper spectral index for interior regions than for the
rim. This can be explained by a standard curved interstellar electron energy
spectrum combined with lower interior magnetic field compared to that near the
outer shock, which results in a larger proportion of steep spectrum emission
for lines-of-sight through the central body of the SNR. HI observations show
structures probably associated with the SNR in the radial velocity range -3 to
-9 km/s and suggest a distance of 0.8+-0.4 kpc for the SNR. This is consistent
with the distance to the radio pulsar 0458+46, offset from the center of HB9 by
23'. However the pulsar spindown and kinematic ages are significantly greater
than estimates of the SNR age: the Sedov age for HB9 is 6600 yr and the
evaporative cloud model yields ages of 4000-7,000 yr.


title:
What triggers galaxy transformations? The environments of post-starburst
  galaxies

abstract:
  (abridged) There are good observational reasons to believe that the
progenitors of red galaxies have undergone starbursts, followed by a
post-starburst phase. We investigate the environments of post-starburst
galaxies by measuring \textsl{(1)} number densities in $8 h^{-1} \mathrm{Mpc}$
radius comoving spheres, \textsl{(2)} transverse distances to nearest
Virgo-like galaxy clusters, and \textsl{(3)} transverse distances to nearest
luminous-galaxy neighbors. We compare the post-starburst galaxies to currently
star-forming galaxies identified solely by A-star excess or $\Halpha$ emission.
We find that post-starburst galaxies are in the same kinds of environments as
star-forming galaxies; this is our ``null hypothesis''. More importantly, we
find that at each value of the A-star excess, the star-forming and
post-starburst galaxies lie in very similar distributions of environment. The
only deviations from our null hypothesis are barely significant: a slight
deficit of post-starburst galaxies (relative to the star-forming population) in
very low-density regions, a small excess inside the virial radii of clusters,
and a slight excess with nearby neighbors. None of these effects is strong
enough to make the post-starburst galaxies a high-density phenomenon, or to
argue that the starburst events are primarily triggered by external tidal
impulses (e.g., from close passages of massive galaxies). The small excess
inside cluster virial radii suggests that some post-starbursts are triggered by
interactions with the intracluster medium, but this represents a very small
fraction of all post-starburst galaxies.


title:
Radio Emission on Sub-Parsec Scales from the Intermediate-Mass Black
  Hole in NGC 4395

abstract:
  The Seyfert 1 nucleus of NGC 4395 is energized by a black hole of 360,000
Solar masses (Peterson et al.), making it one of only two nuclear black holes
of intermediate mass, one thousand to one million Solar masses, detected in the
radio regime. Building upon UV and X-ray evidence for outflows from this
Seyfert nucleus, the VLBI High Sensitivity Array was used at 1.4 GHz to search
for extended structure on scales greater than 5 mas (0.1 pc). Elongated
emission was discovered, extending over 15 mas (0.3 pc) and suggesting an
outflow on sub-parsec scales from this intermediate-mass black hole. The
Seyfert nucleus is located at the center of an elliptical star cluster, and the
elongation position angle of the sub-parsec radio structure is only 19 degrees
from the star cluster's minor axis.


title:
Gravity's Relentless Pull: An interactive, multimedia website about
  black holes for Education and Public Outreach

abstract:
  We have created a website, called "Black Holes: Gravity's Relentless Pull",
which explains the physics and astronomy of black holes for a general audience.
The site emphasizes user participation and is rich in animations and
astronomical imagery. It won the top prize of the 2005 Pirelli INTERNETional
Awards competition for the best communication of science and technology using
the internet. This article provides a brief overview of the site. The site
starts with an opening animation that introduces the basic concept of a black
hole. The user is then invited to embark on a journey from a backyard view of
the night sky to a personal encounter with a singularity. This journey proceeds
through three modules, which allow the user to: find black holes in the night
sky; travel to a black hole in an animated starship; and explore a black hole
from up close. There are also five "experiments" that allow the user to: create
a black hole; orbit around a black hole; weigh a black hole; drop a clock into
a black hole; or fall into a black hole. The modules and experiments offer
goal-based scenarios tailored for novices and children. The site also contains
an encyclopedia of frequently asked questions and a detailed glossary that are
targeted more at experts and adults. The overall result is a website where
scientific knowledge, learning theory, and fun converge. Despite its focus on
black holes, the site also teaches many other concepts of physics, astronomy
and scientific thought. The site aims to instill an appreciation for learning
and an interest in science, especially in the younger users. It can be used as
an aid in teaching introductory astronomy at the undergraduate level.

categories: astro-ph gr-qc physics.ed-ph physics.pop-ph


title: Cosmology with X-ray Cluster Baryons

abstract:
  X-ray cluster measurements interpreted with a universal baryon/gas mass
fraction can theoretically serve as a cosmological distance probe. We examine
issues of cosmological sensitivity for current (e.g. Chandra X-ray Observatory,
XMM-Newton) and next generation (e.g. Con-X, XEUS) observations, along with
systematic uncertainties and biases. To give competitive next generation
constraints on dark energy, we find that systematics will need to be controlled
to better than 1% and any evolution in f_gas (and other cluster gas properties)
must be calibrated so the residual uncertainty is weaker than (1+z)^{0.03}.


title: The Evolution of Central Stars of Planetary Nebulae

abstract:
  The evolution of central stars of planetary nebulae can proceed in several
distinct ways, either leading to H-deficiency or to H-normal surface
composition. Several new simulations of the evolution channels that lead to
H-deficiency are now available, mainly the born-again scenarios that are
triggered by a He-shell flash during the hot pre-white dwarf evolution phase. A
realistic AGB progenitor evolution is important for correct HRD tracks, that
allow mass determinations. New hydrodynamic simulations of He-shell flash
convection including cases with H-ingestion are now performed, and allow a
determination of the convective extra-mixing efficiency. This has direct
consequences for the intershell abundance distribution of AGB stars that can be
observed in the H-deficient CSPN.


title:
Extinction Columns and Intrinsic X-ray Spectra of the Anomalous X-ray
  Pulsars

abstract:
  The X-ray spectra of Anomalous X-ray Pulsars have long been fit by smooth,
empirical models such as the sum of a black-body plus a power law. These
reproduce the ~0.5 to 10 keV range well, but fail at lower and higher energies,
grossly over-predicting the optical and under-predicting the hard X-ray
emission. A poorly constrained source of uncertainty in determining the true,
intrinsic spectra, in particular at lower energies, is the amount of
interstellar extinction. In previous studies, extinction column densities with
small statistical errors were derived as part of the fits of the spectra to
simple continuum models. Different choices of model, however, each produced
statistically acceptable fits, but a wide range of columns. Here, we attempt to
measure the interstellar extinction in a model-independent way, using
individual absorption edges of the elements O, Fe, Ne, Mg and Si in X-ray
grating spectra taken with XMM-Newton. We find that our inferred equivalent
hydrogen column density NH for 4U 0142+61 is a factor of 1.4 lower than the
typically quoted value from black-body plus power-law fits, and is now
consistent with estimates based on the dust scattering halo and visual
extinction. For three other sources, we find column densities consistent with
earlier estimates. We use our measurements to recover the intrinsic spectra of
the AXPs empirically, without making assumptions on what the intrinsic spectral
shapes ought to be. We find that the power-law components that dominate at
higher energies do not extend below the thermal peak.


title:
Adaptive Optics Spectroscopy of the [Fe II] Outflows from HL Tauri and
  RW Aurigae

abstract:
  We present new results of [Fe II] 1.644-micron spectroscopy toward the jets
from HL Tau and RW Aur carried out with the Subaru Telescope combined with the
adaptive optics system. We observed the regions within 2" - 3" from the stars
with the sub-arcsecond resolutions of 0."5 and 0."2 for HL Tau and RW Aur,
respectively. In addition to the strong, high velocity emission extended along
each jet, we detected a blueshifted low velocity emission feature seen as a
wing or shoulder of the high velocity emission at each stellar position.
Detailed analysis shows that the position-velocity diagrams (PVDs) of HL Tau
and RW Aur show a characteristic similar to those of the cold disk wind and
X-wind models in that the [Fe II] line width is broad in the vicinity of the
stellar position and is narrower at the extended jet. A closer comparison
suggests, however, that the disk wind model tends to have too large line width
at the jet while the X-wind model has excess emission on the redshifted side at
the stellar position. The narrow velocity width with symmetric line profiles of
the observed high velocity emission supports an X-wind type model where the
launching region is localized in a small radial range, while the low velocity
emission located away from the star favors the presence of a disk wind. The [Fe
II] emission from the HL Tau jet shows a gap of 0."8 between the redshifted jet
and the star, indicating the presence of an optically thick disk of ~ 160 AU in
radius. The [Fe II] emission from the RW Aur jet shows a marked drop from the
redshifted peak at Y ~ -0."2 toward the star, suggesting that its disk radius
is smaller than 40 AU.


title: Instrumental and Analytic Methods for Bolometric Polarimetry

abstract:
  We discuss instrumental and analytic methods that have been developed for the
first generation of bolometric cosmic microwave background (CMB) polarimeters.
The design, characterization, and analysis of data obtained using Polarization
Sensitive Bolometers (PSBs) are described in detail. This is followed by a
brief study of the effect of various polarization modulation techniques on the
recovery of sky polarization from scanning polarimeter data. Having been
successfully implemented on the sub-orbital Boomerang experiment, PSBs are
currently operational in two terrestrial CMB polarization experiments (QUaD and
the Robinson Telescope). We investigate two approaches to the analysis of data
from these experiments, using realistic simulations of time ordered data to
illustrate the impact of instrumental effects on the fidelity of the recovered
polarization signal. We find that the analysis of difference time streams takes
full advantage of the high degree of common mode rejection afforded by the PSB
design. In addition to the observational efforts currently underway, this
discussion is directly applicable to the PSBs that constitute the polarized
capability of the Planck HFI instrument.


title: Stellar Collapse Dynamics With Neutrino Flavor Changing Neutral Currents

abstract:
  We perform one-zone simulations of the infall epoch of a pre-supernova
stellar core in the presence of neutrino flavor changing scattering
interactions. Our calculations give a self-consistent assessment of the
relationship between flavor changing rates and the reduction in electron
fraction and re-distribution of initial electron lepton number among the
neutrino flavors. We discuss and include in our calculations sub-nuclear
density medium corrections for flavor changing scattering coherence factors. We
find that flavor changing couplings epsilon > 3x10^(-4) in either the electron
neutrino - muon neutrino or electron neutrino - tau neutrino channels result in
a dynamically significant reduction in core electron fraction relatively soon
after neutrino trapping and well before the core reaches nuclear matter
density.


title: The Nature of Blue Early-Type Galaxies in the Goods Fields

abstract:
  We present a study of the nature of the blue early-type galaxies (BEGs) in
the GOODS north and south fields using the GOODS HST/ACS archival data. Using
visual inspection, we have selected 58 BEGs and 113 normal red early-type
galaxies (REGs) in the sample of 1,949 galaxies with spectroscopic redshifts.
We find that the BEGs are generally bluer, fainter, and less-massive than the
REGs, although a few BEGs are exceptionally bright and massive. The number
fraction of the BEGs to total early-type galaxies is almost constant
($\sim0.3$) at $z \le 1.1$. In addition, we find that the size of the BEGs in
given redshift bin decrease as redshift decreases. The BEGs look similar to the
REGs in the images and surface brightness profiles. However, at least 27 BEGs
show traces of tidal disturbances in their fine structures: elongated cores,
off-centered cores, asymmetric internal color distributions, tidally distorted
outer structures, collisional rings, or very nearby companions. Twenty-one BEGs
are detected in the X-ray bands and eleven of them are as luminous as
$L_{0.5-10 {\rm keV}} \ge 10^{43.5} {\rm erg~s}^{-1}$, indicating the existence
of AGNs in their centers. These results show that at least a half of the BEGs
may be descendants of mergers/interacting-galaxies and that at least a quarter
of the BEGs may be AGN-host galaxies. The BEGs may evolve into REGs, and the
size evolution of the BEGs is consistent with the galactic \emph{downsizing}
scenario.


title: The period-luminosity relation for type II Cepheids in globular clusters

abstract:
  We report the result of our near-infrared observations (JHKs) for type II
Cepheids (including possible RV Tau stars) in galactic globular clusters. We
detected variations of 46 variables in 26 clusters (10 new discoveries in seven
clusters) and present their light curves. Their periods range from 1.2 d to
over 80 d. They show a well-defined period-luminosity relation at each
wavelength. Two type II Cepheids in NGC6441 also obey the relation if we assume
the horizontal branch stars in NGC6441 are as bright as those in metal-poor
globular clusters in spite of the high metallicity of the cluster. This result
supports the high luminosity which has been suggested for the RR Lyr variables
in this cluster. The period-luminosity relation can be reproduced using the
pulsation equation (P sqrt(rho)=Q) assuming that all the stars have the same
mass. Cluster RR Lyr variables were found to lie on an extrapolation of the
period-luminosity relation. These results provide important constraints on the
parameters of the variable stars.
  Using Two Micron All-Sky Survey (2MASS) data, we show that the type II
Cepheids in the Large Magellanic Cloud (LMC) fit our period-luminosity relation
within the expected scatter at the shorter periods. However, at long periods
($P>40$ d, i.e. in the RV Tau star range) the LMC field variables are brighter
by about one magnitude than those of similar periods in galactic globular
clusters. The long-period cluster stars also differ from both these LMC stars
and galactic field RV Tau stars in a colour-colour diagram. The reasons for
these differences are discussed.


title: Shell-models of RMHD turbulence and the heating of solar coronal loops

abstract:
  A simplified non-linear numerical model for the development of incompressible
magnetohydrodynamics (MHD) in the presence of a strong magnetic field B0 and
stratification, nicknamed Shell-Atm, is presented. In planes orthogonal to the
mean field, the non-linear incompressible dynamics is replaced by 2D
shell-models for the complex variables u and b, allowing one to reach large
Reynolds numbers while at the same time carrying out sufficiently long time
integrations to obtain a good statistics at moderate computational cost. The
shell-models of different planes are coupled by Alfven waves propagating along
B0. The model may be applied to open or closed magnetic field configurations
where the axial field dominates and the plasma pressure is low; here we apply
it to the specific case of a magnetic loop of the solar corona heated via
turbulence driven by photospheric motions, and we use statistics for its
analysis. The Alfven waves interact non-linearly and form turbulent spectra in
the directions perpendicular and, via propagation, also parallel to the mean
field. A heating function is obtained, and is shown to be intermittent; the
average heating is consistent with values required for sustaining a hot corona,
and is proportional to the aspect ratio of the loop to the power -1.5;
characteristic properties of heating events are distributed as power-laws.
Cross-correlations show a delay of dissipation compared to energy content.


title:
Cosmic shear analysis of archival HST/ACS data: I. Comparison of early
  ACS pure parallel data to the HST/GEMS Survey

abstract:
  This is the first paper of a series describing our measurement of weak
lensing by large-scale structure using archival observations from the Advanced
Camera for Surveys (ACS) on board the Hubble Space Telescope (HST).
  In this work we present results from a pilot study testing the capabilities
of the ACS for cosmic shear measurements with early parallel observations and
presenting a re-analysis of HST/ACS data from the GEMS survey and the GOODS
observations of the Chandra Deep Field South (CDFS). We describe our new
correction scheme for the time-dependent ACS PSF based on observations of
stellar fields. This is currently the only technique which takes the full time
variation of the PSF between individual ACS exposures into account. We estimate
that our PSF correction scheme reduces the systematic contribution to the shear
correlation functions due to PSF distortions to < 2*10^{-6} for galaxy fields
containing at least 10 stars. We perform a number of diagnostic tests
indicating that the remaining level of systematics is consistent with zero for
the GEMS and GOODS data confirming the success of our PSF correction scheme.
For the parallel data we detect a low level of remaining systematics which we
interpret to be caused by a lack of sufficient dithering of the data.
  Combining the shear estimate of the GEMS and GOODS observations using 96
galaxies arcmin^{-2} with the photometric redshift catalogue of the GOODS-MUSIC
sample, we determine a local single field estimate for the mass power spectrum
normalisation sigma_{8,CDFS}=0.52^{+0.11}_{-0.15} (stat) +/- 0.07 (sys) (68%
confidence assuming Gaussian cosmic variance) at fixed Omega_m=0.3 for a
LambdaCDM cosmology. We interpret this exceptionally low estimate to be due to
a local under-density of the foreground structures in the CDFS.


title: Cosmological Dynamics from Modified $f(R)$ Gravity in Einstein Frame

abstract:
  In this paper, we investigate and analyze the cosmological dynamics of the
universe, with an effect of modified $f(R)$ gravity emerging at cosmological
scale. We choose the Einstein frame as a physical frame. We consider phase
portraits of the universe at the late time from modified $f(R)$ gravity model.
This result gives our universe an acceleration phase expansion without
introducing existence of dark energy dominating our universe.


title:
Structure of pair winds from compact objects with application to
  emission from bare strange stars

abstract:
  We present the results of numerical simulations of stationary, spherically
outflowing, electron-positron pair winds, with total luminosities in the range
10^{34}- 10^{42} ergs/s. In the concrete example described here, the wind
injection source is a hot, bare, strange star, predicted to be a powerful
source of electron-positron pairs created by the Coulomb barrier at the quark
surface. We find that photons dominate in the emerging emission, and the
emerging photon spectrum is rather hard and differs substantially from the
thermal spectrum expected from a neutron star with the same luminosity. This
might help distinguish the putative bare strange stars from neutron stars.


title:
Uranium partitioning between liquid iron and silicate melt at high
  pressures: implications for uranium solubility in planetary cores

abstract:
  We have investigated the partitioning of U between silicate melt and Fe
liquid at pressures of 3.0 to14.5 GPa and temperatures of 1660 to 2500 oC. The
solubility of U in liquid Fe is in the range of 0.6 to 800 ppm and increases
with temperature (T) and pressure (P). When P = or > 7 GPa and T > Tmelt of the
silicate phase (olivine), the U concentration in Fe is 3 to 5 times greater
than for run products where T < Tmelt of the silicate phase. Correspondingly,
partitioning coefficient DU values can reach 0.031 at 8.5 GPa (using BN sample
container) and 0.036 at 14.5 GPa (using graphite sample container). This
implies that if a terrestrial-type planetary core with a pure Fe composition
formed from a deep magma ocean (T > Tmelt of the silicate phase), then > 2.4
ppb U could have entered the core. Alternatively, if a core with same
composition formed by percolation (T < Tmelt of the silicate phase), then based
on the experimental results indicating DU increases with increasing P, 1 to 4
ppb U may have entered the core. The concentration of Si in liquid Fe also
increases with pressure. The concentration of Ca is < 0.44 wt % for most
samples and no relation with U concentration is found, which indicates that U
may alloy with Fe directly. If Si concentration in the Fe phase can be used as
an indicator of oxygen fugacity, then the increase in Si and U with pressure
suggests a pressure dependent decrease in oxygen fugacity. This supports U (and
possibly also Si) inclusion in the the core of Earth at the time of core
formation. The implications for radioactive heating in the planetary cores are
briefly discussed. Keywords: Uranium; partition coefficients; high pressure;
dynamos; planetary cores; heat sources, LA-ICP-MS.


title: Light Curves from an MHD Simulation of a Black Hole Accretion Disk

abstract:
  We use a relativistic ray-tracing code to calculate the light curves observed
from a global general relativistic magneto-hydrodynamic simulation of an
accretion flow onto a Schwarzschild black hole. We apply three basic emission
models to sample different properties of the time-dependent accretion disk.
With one of these models, which assumes thermal blackbody emission and
free-free absorption, we can predict qualitative features of the high-frequency
power spectrum from stellar-mass black holes in the "Thermal Dominant" state.
The simulated power spectrum is characterized by a power law of index Gamma ~ 3
and total rms fractional variance of <~ 2% above 10 Hz. For each emission
model, we find that the variability amplitude should increase with increasing
inclination angle. On the basis of a newly-developed formalism for quantifying
the significance of quasi-periodic oscillations (QPOs) in simulation data, we
find that these simulations are able to identify any such features with
(rms/mean) amplitudes >~ 1 % near the orbital frequency at the inner-most
stable orbit. Initial results indicate the existence of transient QPO peaks
with frequency ratios of nearly 2:3 at a 99.9% confidence limit, but they are
not generic features because at any given time they are seen only from certain
observer directions. Additionally, we present detailed analysis of the
azimuthal structure of the accretion disk and the evolution of density
perturbations in the inner disk. These "hot spot" structures appear to be
roughly self-similar over a range of disk radii, with a single characteristic
size \delta\phi=25 deg and \delta r/r=0.3, and typical lifetimes T_l ~ 0.3
T_orb.


title:
Simulation of Coherent Non-Linear Neutrino Flavor Transformation in the
  Supernova Environment I: Correlated Neutrino Trajectories

abstract:
  We present results of large-scale numerical simulations of the evolution of
neutrino and antineutrino flavors in the region above the late-time
post-supernova-explosion proto-neutron star. Our calculations are the first to
allow explicit flavor evolution histories on different neutrino trajectories
and to self-consistently couple flavor development on these trajectories
through forward scattering-induced quantum entanglement. Employing the
atmospheric-scale neutrino mass-squared difference and values of theta_13
allowed by current bounds, we find transformation of neutrino and antineutrino
flavors over broad ranges of energy and luminosity in roughly the ``bi-polar''
collective mode. We find that this large-scale flavor conversion, largely
driven by the flavor off-diagonal neutrino-neutrino forward scattering
potential, sets in much closer to the proto-neutron star than simple estimates
based on flavor-diagonal potentials and Mikeheyev-Smirnov-Wolfenstein evolution
would indicate. In turn, this suggests that models of r-process nucleosynthesis
sited in the neutrino-driven wind could be affected substantially by
active-active neutrino flavor mixing, even with the small measured neutrino
mass-squared differences.


title: Identification of New M Dwarfs in the Solar Neighborhood

abstract:
  We present the results from a spectroscopic study of 1080 nearby active M
dwarfs, selected by correlating the 2MASS and ROSAT catalogs. We have derived
the spectral types and estimated distances for all of our stars. The spectral
types range between K5 and M6. Nearly half of our stars lie within 50 pc. We
have measured the equivalent width of the H alpha emission line. Our targets
show an increase in chromospheric activity from early to mid-spectral types,
with a peak in activity around M5. Using the count rate and hardness ratios
obtained from the ROSAT catalog, we have derived the X-ray luminosities. Our
stars display a "saturation-type" relation between the chromospheric and
coronal activity. The relation is such that log (Lx/Lbol) remains "saturated"
at a value of about -3 for varying H alpha equivalent width. We have found 568
matches in the USNO-B catalog, and have derived the tangential velocities for
these stars. There is a slight trend of decreasing chromospheric activity with
age, such that the stars with higher Vtan have lower H alpha equivalent widths.
The coronal emission, however, remains saturated at a value of log (Lx/Lbol) -3
for varying tangential velocities, suggesting that the coronal activity remains
saturated with age. We do not find any break in the saturation-type relation at
the spectral type where stars become fully convective (~M3.5). Most of the
stars in our sample show more coronal emission than the dMe stars in the Hyades
and Praesepe clusters, and have Vtan< 40km/s, suggesting a young population.


title:
The importance of interloper removal in galaxy clusters: saving more
  objects for the Jeans analysis

abstract:
  We study the effect of contamination by interlopers in kinematic samples of
galaxy clusters. We demonstrate that without the proper removal of interlopers
the inferred parameters of the mass distribution in the cluster are strongly
biased towards higher mass and lower concentration. The interlopers are removed
using two procedures previously shown to work most efficiently on simulated
data. One is based on using the virial mass estimator and calculating the
maximum velocity available to cluster members and the other relies on the ratio
of the virial and projected mass estimators. We illustrate the performance of
the methods in detail using the example of A576, a cluster with a strong
uniform background contamination, and compare the case of A576 to 15 other
clusters with different degree of contamination. We model the velocity
dispersion and kurtosis profiles obtained for the cleaned data samples of these
clusters solving the Jeans equations to estimate the mass, concentration and
anisotropy parameter. We present the mass-concentration relation for the total
sample of 22 clusters.


title:
An upper limit to the photon fraction in cosmic rays above 10^19 eV from
  the Pierre Auger Observatory

abstract:
  An upper limit of 16% (at 95% c.l.) is derived for the photon fraction in
cosmic rays with energies greater than 10^19 eV, based on observations of the
depth of shower maximum performed with the hybrid detector of the Pierre Auger
Observatory. This is the first such limit on photons obtained by observing the
fluorescence light profile of air showers. This upper limit confirms and
improves on previous results from the Haverah Park and AGASA surface arrays.
Additional data recorded with the Auger surface detectors for a subset of the
event sample, support the conclusion that a photon origin of the observed
events is not favored.


title: Tracing Quasar Accretion Rates at Higher Redshifts

abstract:
  In this work we connect some measurable properties of the CIV1549 emission
line with the quasar accretion rates (Eddington ratios). A tight correlation is
found for a sample of more than a hundred nearby objects, suggesting a possible
method for a relatively accurate estimate of the Eddington ratio of
high-redshift quasars, at least for the radio-quiet ones. This paper further
confirms the existing notion that the CIV changes (shifts) are mostly driven by
the accretion rate.


title:
Consistency of the black hole mass determination in AGN from the
  reverberation and the X-ray excess variance method

abstract:
  Values of black hole masses are frequently determined with the help of the
reverberation method. This method requires a specific geometrical factor
related to the distribution of the orbits of the Broad Line Region clouds.
Onken et al. determined the value f^2= 1.37+/-0.45 from the black hole mass -
dispersion relation. In this paper we determine this factor using an
independent mass determination from the X-ray variance method for a number of
Seyfert 1 galaxies and comparing them with the reverberation results by
Peterson et al. We obtain mean value f^2 = 1.12 +/- 0.54, consistent with Onken
et al. Both values are larger than the value 0.75 corresponding to a spherical
geometry. It indicates that most probably all values of the black hole masses
obtained with the use of the Kaspi et al. formulae should be multiplied by a
factor of \sim 1.7. This also shows that the Broad Line Region is rather flat,
and hints for a dependence of the factor f^2 on a source inclination seem to be
present in the data.


title:
GaBoDS: The Garching-Bonn Deep Survey: VII. Probing galaxy bias using
  weak gravitational lensing

abstract:
  [ABRIDGED] The weak gravitational lensing effect is used to infer matter
density fluctuations within the field-of-view of the Garching-Bonn Deep Survey
(GaBoDS). This information is employed for a statistical comparison of the
galaxy distribution to the total matter distribution. The result of this
comparison is expressed by means of the linear bias factor, b, the ratio of
density fluctuations, and the correlation factor $r$ between density
fluctuations. The total galaxy sample is divided into three sub-samples using
R-band magnitudes and the weak lensing analysis is applied separately for each
sub-sample. Together with the photometric redshifts from the related COMBO-17
survey we estimate the typical mean redshifts of these samples with
$\bar{z}=0.35, 0.47, 0.61$, respectively. For all three samples, a slight
galaxy anti-bias, b~0.8+-0.1, on scales of a few Mpc/h is found; the bias
factor shows evidence for a slight scale-dependence. The correlation between
galaxy and (dark) matter distribution is high, r~0.6+-0.2, indicating a
non-linear or/and stochastic biasing relation between matter and galaxies.
Between the three samples no significant evolution with redshift is found.


title: The Herschel/PACS 2560 bolometers imaging camera

abstract:
  The development program of the flight model imaging camera for the PACS
instrument on-board the Herschel spacecraft is nearing completion. This camera
has two channels covering the 60 to 210 microns wavelength range. The focal
plane of the short wavelength channel is made of a mosaic of 2x4 3-sides
buttable bolometer arrays (16x16 pixels each) for a total of 2048 pixels, while
the long wavelength channel has a mosaic of 2 of the same bolometer arrays for
a total of 512 pixels. The 10 arrays have been fabricated, individually tested
and integrated in the photometer. They represent the first filled arrays of
fully collectively built bolometers with a cold multiplexed readout, allowing
for a properly sampled coverage of the full instrument field of view. The
camera has been fully characterized and the ground calibration campaign will
take place after its delivery to the PACS consortium in mid 2006. The
bolometers, working at a temperature of 300 mK, have a NEP close to the BLIP
limit and an optical bandwidth of 4 to 5 Hz that will permit the mapping of
large sky areas. This paper briefly presents the concept and technology of the
detectors as well as the cryocooler and the warm electronics. Then we focus on
the performances of the integrated focal planes (responsivity, NEP, low
frequency noise, bandwidth).


title: Description of Stellar Acoustic Modes Using the Local Wave Concept

abstract:
  An understanding of stellar acoustic oscillations is attempted, using the
local wave concept in semi-analytical calculations. The local homogeneity
approximation allows to obtain simplified equations that can nevertheless
describe the wave behavior down to the central region, as the gravitational
potential perturbation is not neglected. Acoustic modes are calculated as
classical standing waves in a cavity, by determining the cavity limits and the
wave phases at these limits. The internal boundary condition is determined by a
fitting with an Airy function. The external boundary condition is defined as
the limit where the spatial variation of the background is important compared
to the wavelength. This overall procedure is in accordance with the JWKB
approximation. When comparing the results with numerical calculations, some
drawbacks of the isothermal atmosphere approximation are revealed. When
comparing with seismic observations of the Sun, possible improvements at the
surface of solar models are suggested. The present semi-analytical method can
potentially predict eigenfrequencies at the precision of +-3microHz in the
range 800-5600 microHz, for the degrees l=0-10. A numerical calculation using
the same type of external boundary conditions could reach a global agreement
with observations better than 1 microHz. This approach could contribute to
better determine the absolute values of eigenfrequencies for asteroseismology.


title:
Young Massive Clusters - Formation Efficiencies and (Initial) Mass
  Functions

abstract:
  Globular clusters are often assumed to be good tracers of major star
formation episodes in their host galaxies. While observations over the past 2
decades have confirmed the presence of young objects with globular cluster-like
properties in many galaxies, it is still not well understood exactly how the
formation efficiency of bound star clusters relative to field stars and their
mass spectrum depend on external factors. The cluster initial mass function
typically appears to be consistent with a power-law with a slope of about -2,
but most attempts to constrain any upper limit on the CIMF have been limited by
size-of-sample effects. However, evidence is starting to accumulate for
possible truncation of the cluster mass function. It is tentatively suggested
that the upper mass limit may currently be at about 10^5 Msun in the Milky Way
disk, while there are indications that it is about 5x10^5 Msun in M51 and about
2x10^6 Msun in the Antennae. Some extreme starbursts (e.g. Arp 220, NGC 7252)
are (or were) able to form clusters as massive as 10^7 Msun. The overall
formation efficiency of star clusters (relative to field stars) in the Galactic
bulge may not have been much different from that in the disk today, but was
probably significantly higher for metal-poor GCs in halos.


title: Integrated Sachs-Wolfe effect in the era of precision cosmology

abstract:
  Recent detections of the Integrated Sachs-Wolfe effect through the
correlation of the cosmic microwave background temperature anisotropy with
traces of large scale structure provided independent evidence for the expansion
of the universe being dominated by something other than matter. Even with
perfect data, statistical errors will limit the accuracy of such measurements
to worse than 10%. On the other hand, the extraordinary sensitivity of the ISW
effect to the details of structure formation should help to make up for the
lack of precision. In these conference proceedings I discuss the extent to
which future ISW measurements can help in testing the physics responsible for
the observed cosmic acceleration.


title: The atypical emission-line star Hen3-209

abstract:
  We analyse observations, spanning 15 years, dedicated to the extreme
emission-line object Hen3-209. Our photometric data indicate that the
luminosity of the star undergoes marked variations with a peak-to-peak
amplitude of 0.65mag. These variations are recurrent, with a period of
16.093+-0.005d. The spectrum of Hen3-209 is peculiar with many different lines
(HI, HeI, FeII,...) showing P Cygni profiles. The line profiles are apparently
changing in harmony with the photometry. The spectrum also contains [OIII]
lines that display a saddle profile topped by three peaks, with a maximum
separation of about 600km/s. Hen3-209 is most likely an evolved luminous object
suffering from mass ejection events and maybe belonging to a binary system.


title:
RApid Temporal Survey - RATS II: Followup observations of 4 newly
  discovered short period variables

abstract:
  The RApid Temporal Survey (RATS) is a survey to detect objects whose optical
intensity varies on timescales of less than ~70 min. In our pilot dataset taken
with the INT and the Wide Field Camera in Nov 2003 we discovered nearly 50 new
variable objects. Many of these varied on timescales much longer than 1 hr.
However, only 4 objects showed a modulation on a timescale of 1 hour or less.
This paper presents followup optical photometry and spectroscopy of these 4
objects. We find that RAT J0455+1305 is a pulsating (on a period of 374 sec)
subdwarf B (sdB) star of the EC 14026 type. We have modelled its spectrum and
determine Teff = 29,200+/- 1900K and log g = 5.2+/-0.3 which locates it on the
cool edge of the EC 14026 instability strip. It has a modulation amplitude
which is one of the highest of any known EC 14026 star. Based on their spectra,
photometric variability and their infra-red colours, we find that RAT
J0449+1756, RAT J0455+1254 and RAT J0807+1510 are likely to be SX Phe stars -
dwarf Delta Sct stars. Our results show that our observing strategy is a good
method for finding rare pulsating stars.


title:
Ultra-high energy cosmic rays, cascade gamma-rays, and high-energy
  neutrinos from gamma-ray bursts

abstract:
  Gamma-ray bursts (GRBs) are sources of energetic, highly variable fluxes of
gamma rays, which demonstrates that they are powerful particle accelerators.
Besides relativistic electrons, GRBs should also accelerate high-energy
hadrons, some of which could escape cooling to produce ultra-high energy cosmic
rays (UHECRs). Acceleration of high-energy hadrons in GRB blast waves will be
established if high-energy neutrinos produced through photopion interactions in
the blast wave are detected from GRBs. Limitations on the energy in nonthermal
hadrons and the number of expected neutrinos are imposed by the fluxes from
pair-photon cascades initiated in the same processes that produce neutrinos.
Only the most powerful bursts at fluence levels >~ 3e-4 erg/cm^2 offer a
realistic prospect for detection of >> TeV neutrinos. Detection of high-energy
neutrinos is likely if GRB blast waves have large baryon loads and Doppler
factors <~ 200. Cascade gamma rays will accompany neutrino production and might
already have been detected as anomalous emission components in the spectra of
some GRBs. Prospects for detection of GRBs in the Milky Way are also
considered.


title:
Discovery of Very High Energy $\gamma$-Rays from Markarian~180 Triggered
  by an Optical Outburst

abstract:
  The high-frequency-peaked BL Lacertae object Markarian~180 (Mrk~180) was
observed to have an optical outburst in 2006 March, triggering a Target of
Opportunity observation with the MAGIC telescope. The source was observed for
12.4 hr and very high energy $\gamma$-ray emission was detected with a
significance of 5.5 $\sigma$. An integral flux above 200 GeV of
$(2.3\pm0.7)\times10^{-11} {cm}^{-2} {s}^{-1}$ was measured, corresponding to
11% of the Crab Nebula flux. A rather soft spectrum with a photon index of
$-3.3\pm0.7$ has been determined. No significant flux variation was found.