title:
High-energy gamma-ray emission from the inner jet of LS I+61 303: the
  hadronic contribution revisited

abstract:
  LS I+61 303 has been detected by the Cherenkov telescope MAGIC at very high
energies, presenting a variable flux along the orbital motion with a maximum
clearly separated from the periastron passage. In the light of the new
observational constraints, we revisit the discussion of the production of
high-energy gamma rays from particle interactions in the inner jet of this
system. The hadronic contribution could represent a major fraction of the TeV
emission detected from this source. The spectral energy distribution resulting
from p-p interactions is recalculated. Opacity effects introduced by the photon
fields of the primary star and the stellar decretion disk are shown to be
essential in shaping the high-energy gamma-ray light curve at energies close to
200 GeV. We also present results of Monte Carlo simulations of the
electromagnetic cascades developed very close to the periastron passage. We
conclude that a hadronic microquasar model for the gamma-ray emission in LS I
+61 303 can reproduce the main features of its observed high-energy gamma-ray
flux.


title:
Ultraviolet Spectroscopy of Comet 9P/Tempel 1 with Alice/Rosetta during
  the Deep Impact Encounter

abstract:
  We report on spectroscopic observations of periodic comet 9P/Tempel 1 by the
Alice ultraviolet spectrograph on the Rosetta spacecraft in conjunction with
NASA's Deep Impact mission. Our objectives were to measure an increase in
atomic and molecular emissions produced by the excavation of volatile
sub-surface material. We unambiguously detected atomic oxygen emission from the
quiescent coma but no enhancement at the 10% (1-sigma) level following the
impact. We derive a quiescent water production rate of 9 x 10^27 molecules per
second with an estimated uncertainty of 30%. Our upper limits to the volatiles
produced by the impact are consistent with other estimates.


title:
A multi-wavelength census of star formation activity in the young
  embedded cluster around Serpens/G3-G6

abstract:
  Aims. The aim of this paper is to characterise the star formation activity in
the poorly studied embedded cluster Serpens/G3-G6, located ~ 45' (3 pc) to the
south of the Serpens Cloud Core, and to determine the luminosity and mass
functions of its population of Young Stellar Objects (YSOs).
  Methods. Multi-wavelength broadband photometry was obtained to sample the
near and mid-IR spectral energy distributions to separate YSOs from field stars
and classify the YSO evolutionary stage. ISOCAM mapping in the two filters LW2
(5-8.5 um) and LW3 (12-18 um) of a 19' x 16' field was combined with JHKs data
from 2MASS, Ks data from Arnica/NOT, and L' data from SIRCA/NOT. Continuum
emission at 1.3 mm (IRAM) and 3.6 cm (VLA) was mapped to study the cloud
structure and the coldest/youngest sources. Deep narrow band imaging at the
2.12 um S(1) line of H2 from NOTCam/NOT was obtained to search for signs of
bipolar outflows.
  Results. We have strong evidence for a stellar population of 31 Class II
sources, 5 flat-spectrum sources, 5 Class I sources, and two Class 0 sources.
Our method does not sample the Class III sources. The cloud is composed of two
main dense clumps aligned along a ridge over ~ 0.5 pc plus a starless core
coinciding with absorption features seen in the ISOCAM maps. We find two
S-shaped bipolar collimated flows embedded in the NE clump, and propose the two
driving sources to be a Class 0 candidate (MMS3) and a double Class I (MMS2).
For the Class II population we find a best age of ~ 2 Myr and compatibility
with recent Initial Mass Functions (IMFs) by comparing the observed Class II
luminosity function (LF), which is complete to 0.08 L_sun, to various model LFs
with different star formation scenarios and input IMFs.


title:
The Origin of Diffuse X-ray and $\gamma$-ray Emission from the Galactic
  Center Region: Cosmic Ray Particles

abstract:
  (Abridged) The inner couple hundred pcs of our Galaxy is characterized by
significant amount of synchrotron-emitting gas, which appears to co-exist with
a large reservoir of molecular gas. The spatial correlation between fluorescent
Fe K-alpha line emission at 6.4 keV and molecular line emission from Galactic
center molecular clouds has been explained as reflected X-rays from a past
outburst of Sgr A*. Here we present multi-wavelength study of a representative
Galactic center cloud Sgr C using Chandra, VLA and FCRAO. We note a correlation
between the nonthermal radio filaments in Sgr C and the X-ray features,
suggesting that the two are related. We account for this distribution in terms
of the impact of the relativistic particles from local (nonthermal filaments)
and extended sources with diffuse neutral gas producing both a nonthermal
bremsstrahlung X-ray continuum emission, as well as diffuse 6.4 keV line
emission. The production rate of Fe Kalpha photons associated with the
injection of electrons into a cloud as a function of column density is
calculated. The required energy density of low-energy cosmic rays associated
with the synchrotron emitting radio filaments or extended features is estimated
to be in the range between 20 and $\sim10^3$ eV cm^-3 for Sgr C, Sgr B1, Sgr
B2, and ``the 45 and -30 \kms'' clouds. We also generalize this idea to explain
the pervasive production of diffuse Kalpha line and TeV emission from the
Galactic center molecular clouds. In particular, we suggest that IC scattering
of the sub-millimeter radiation from dust by relativistic electrons may
contribute substantially to the large-scale diffuse TeV emission observed
towards the central regions of the Galaxy.


title: CZT imaging detectors for ProtoEXIST

abstract:
  We describe the detector development for a balloon-borne wide-field hard
X-ray (20 - 600 keV) telescope, ProtoEXIST. ProtoEXIST is a pathfinder for both
technology and science of the proposed implementation of the Black Hole Finder
Probe, Energetic X-ray Imaging Survey telescope (EXIST). The principal
technology challenge is the development of large area, close-tiled modules of
imaging CZT detectors (1000 cm2 for ProtoEXIST1). We review the updates of the
detector design and package concept for ProtoEXIST1 and report the current
development status of the CZT detectors, using calibration results of our basic
detector unit - 2 x 2 x 0.5 cm CZT crystals with 2.5 mm pixels (8 x 8 array).
The current prototype (Rev1) of our detector crystal unit (DCU) shows ~4.5 keV
electronics noise (FWHM), and the radiation measurements show the energy
resolution (FWHM) of the units is 4.7 keV (7.9%) at 59.5 keV, 5.6 keV (4.6%) at
122 keV, and 7.6 keV (2.1%) at 356 keV. The new (Rev2) DCU with revised design
is expected to improve the resolution by ~30%.


title: Galactic structure studies from BATC survey

abstract:
  We present an analysis of the photometric parallaxes of stars in 21 BATC
fields carried out with the National Astronomical Observatories (NAOC) 60/90 cm
Schmidt Telescope in 15 intermediate-band filters from 3000 to 10000 {\AA}. In
this study, we have adopted a three-component (thin disk, thick disk and halo)
model to analyze star counts information. By calculating the stellar space
density as a function of distance from the Galactic plane, we determine that
the range of scale height for the thin disk varies from 220 to 320 pc. Although
220 pc seems an extreme value, it is close to the lower limit in the
literature. The range of scale height for the thick disk is from 600 to 1100
pc, and the corresponding space number density normalization is 7.0-1.0% of the
thin disk. We find that the scale height of the disk may be variable with
observed direction, which cannot simply be attributed to statistical errors.
Possibly the main reasons can be attributed to the disk (mainly the thick disk)
is flared, with a scale height increasing with radius. The structure is
consistent with merger origin for the thick disk formation. Adopting a de
Vaucouleurs $r^{1/4}$ law halo, we also find that the axis ratio towards the
Galactic center is somewhat flatter ($\sim 0.4$), while the shape of the halo
in the anticentre and antirotation direction is rounder with $c/a> 0.4$. Our
results show that star counts in different lines of sight can be used directly
to obtain a rough estimate of the shape of the stellar halo. Our solutions
support the Galactic models with a flattened inner halo, possibly it is formed
by a merger early in the Galaxy's history.


title: Modeling the Emission Processes in Blazars

abstract:
  Blazars are the most violent steady/recurrent sources of high-energy
gamma-ray emission in the known Universe. They are prominent emitters of
electromagnetic radiation throughout the entire electromagnetic spectrum. The
observable radiation most likely originates in a relativistic jet oriented at a
small angle with respect to the line of sight. This review starts out with a
general overview of the phenomenology of blazars, including results from a
recent multiwavelength observing campaign on 3C279. Subsequently, issues of
modeling broadband spectra will be discussed. Spectral information alone is not
sufficient to distinguish between competing models and to constrain essential
parameters, in particular related to the primary particle acceleration and
radiation mechanisms in the jet. Short-term spectral variability information
may help to break such model degeneracies, which will require snap-shot
spectral information on intraday time scales, which may soon be achievable for
many blazars even in the gamma-ray regime with the upcoming GLAST mission and
current advances in Atmospheric Cherenkov Telescope technology. In addition to
pure leptonic and hadronic models of gamma-ray emission from blazars,
leptonic/hadronic hybrid models are reviewed, and the recently developed
hadronic synchrotron mirror model for TeV gamma-ray flares which are not
accompanied by simultaneous X-ray flares (``orphan TeV flares'') is revisited.


title:
Towards a Solution of the Polycyclic Aromatic Hydrocarbon - Diffuse
  Interstellar Band Hypothesis

abstract:
  A novel theoretical method is developed to study the polycyclic aromatic
hydrocarbon - diffuse interstellar band (PAH-DIB) hypothesis. In this method, a
computer program is used to enumerate all PAH molecules with up to a specific
number of fused benzene rings. Fast quantum chemical calculations are then
employed to calculate the electronic transition energies, oscillator strengths,
and rotational constants of these molecules. An electronic database of all PAHs
with up to any specific number of benzene rings can be constructed this way.
Comparison of the electronic transition energies, oscillator strengths, and
rotational band contours of all PAHs in the database with astronomical spectra
allows one to identify possible individual PAH carriers of some of the intense
narrow DIBs. Using the current database containing up to 10 benzene rings we
have selected 8 closed-shell PAHs as possible carriers of the intense
lambda6614 DIB.


title: HST Stellar Standards with 1% Accuracy in Absolute Flux

abstract:
  Free of any atmospheric contamination, HST provides the best available
spectrophotometry from the far-UV to the near-IR for stars as faint as V~16.
The HST CALSPEC standard star network is based on 3 standard candles: the hot,
pure hydrogen white dwarf (WD) stars G191B2B, GD153, and GD71, which have
Hubeny NLTE model flux calculations that require the atomic physics for only
one atom. These model flux distributions are normalized to the absolute flux
for Vega of 3.46x10^{-9} erg cm^{-2} s^{-1} \AA^{-1} at 5556\AA using precise
Landolt V band photometry and the V bandpass function corrected for atmospheric
transmission by M. Cohen. The 3 primary WD standards provide absolute flux
calibrations for FOS, STIS, and NICMOS spectrophotometry from these instruments
on the HST. About 32 stellar spectral energy distributions (SEDs) have been
constructed with a primary pedigree from the STIS data, which extends from 1150
\AA for the hot stars to a long wavelength limit of 1\mu m. NICMOS grism
spectrophotometry provides an extension to 1.9\mu m in the IR for 17 of the HST
standards and longward to 2.5\mu m for a few of the brighter stars. Included
among these HST standards are Vega, the Sloan standard BD+17$^{\circ}$4708, 3
bright solar analog candidates, 3 cool stars of type M or later, and 5 hot WDs.
In addition, 4 K giants and 4 main sequence A-stars have NICMOS
spectrophotometry from 0.8-2.5\mu m. The WD fluxes are compared to their
modeled SEDs and demonstrate an internal precision of 1-2%, while the A-stars
agree with the Cohen IR fluxes to ~2%. Three solar analog candidate stars
differ from the solar spectrum by up to 10% in the region of heavy line
blanketing from 3000-4000 \AA and show differences in shape of ~5% in the IR
around 1.8\mu m.


title:
Using the Galactic Dynamics of M7 Dwarfs to Infer the Evolution of Their
  Magnetic Activity

abstract:
  We present a spectroscopic study and dynamical analysis of ~2600 M7 dwarfs.
We confirm our previous finding that the fraction of magnetically active stars
decreases with vertical distance from the Galactic plane. We also show that the
mean luminosity of the H-alpha emission has a small but statistically
significant decrease with distance. Using space motions for ~1300 stars and a
simple one-dimensional dynamical simulation, we demonstrate that the drop in
the activity fraction of M7 dwarfs can be explained by thin disk dynamical
heating and a rapid decrease of magnetic activity at a mean stellar age of ~6-7
Gyr.


title:
Does the AGN Unified Model Evolve with Redshift? Utilizing the X-ray
  Background to Predict the Mid-Infrared Emission of AGN

abstract:
  Deep X-ray surveys by Chandra and XMM-Newton have resolved about 80% of the
2-10 keV cosmic extragalactic X-ray background (CXRB) into point sources, the
majority of which are obscured AGN. The obscuration might be connected to
processes within the host galaxy, possibly the star-formation rate. Here, we
use the results of CXRB synthesis calculations as input to detailed Cloudy
simulations in order to predict the evolution of AGN properties at several
mid-IR wavelengths. Computations were performed for three different evolutions
of the AGN type 2/type 1 ratio between z=0 and 1: where the ratio increased as
(1+z)^{0.9}, as (1+z)^{0.3} and one with no redshift evolution. Models were
calculated with the inner radius of the absorbing gas and dust at 1 pc or at 10
pc. Comparing the results of the calculations to combined X-ray and Spitzer
data of AGN shows that the predicted spectral energy distributions are a good
description of average AGNs found in the deep surveys. The existing data
indicates that the mid-IR emission from an average AGN is best described by
models where the attenuating material is ~10 pc from the central engine. We
present the expected Spitzer cumulative number count distributions and the
evolution of the total AGN (type 1 + type 2) luminosity function (LF) between
z=0 and 1 at rest-frame 8 microns and 30 microns for the three evolutionary
scenarios. The mid-IR AGN LF will be an excellent tool to measure the evolution
of the covering factor of the gas and dust from z~0 to 1.


title:
Slow Roll Reconstruction: Constraints on Inflation from the 3 Year WMAP
  Dataset

abstract:
  We study the constraints on the inflationary parameter space derived from the
3 year WMAP dataset using ``slow roll reconstruction'', using the SDSS galaxy
power spectrum to gain further leverage where appropriate. This approach
inserts the inflationary slow roll parameters directly into a Monte Carlo
Markov chain estimate of the cosmological parameters, and uses the inflationary
flow hierarchy to compute the parameters' scale-dependence. We work with the
first three parameters (epsilon, eta and xi) and pay close attention to the
possibility that the 3 year WMAP dataset contains evidence for a ``running''
spectral index, which is dominated by the xi term. Mirroring the WMAP team's
analysis we find that the permitted distribution of xi is broad, and centered
away from zero. However, when we require that inflationary parameters yield at
least 30 additional e-folds of inflation after the largest observable scales
leave the horizon, the bounds on xi tighten dramatically. We make use of the
absence of an explicit pivot scale in the slow roll reconstruction formalism to
determine the dependence of the computed parameter distributions on the pivot.
We show that the choice of pivot has a significant effect on the inferred
constraints on the inflationary variables, and the spectral index and running
derived from them. Finally, we argue that the next round of cosmological data
can be expected to place very stringent constraints on the region of parameter
space open to single field models of slow roll inflation.


title:
RAISHIN: A High-Resolution Three-Dimensional General Relativistic
  Magnetohydrodynamics Code

abstract:
  We have developed a new three-dimensional general relativistic
magnetohydrodynamic (GRMHD) code, RAISHIN, using a conservative, high
resolution shock-capturing scheme. The numerical fluxes are calculated using
the Harten, Lax, & van Leer (HLL) approximate Riemann solver scheme. The
flux-interpolated, constrained transport scheme is used to maintain a
divergence-free magnetic field. In order to examine the numerical accuracy and
the numerical efficiency, the code uses four different reconstruction methods:
piecewise linear methods with Minmod and MC slope-limiter function, convex
essentially non-oscillatory (CENO) method, and piecewise parabolic method (PPM)
using multistep TVD Runge-Kutta time advance methods with second and
third-order time accuracy. We describe code performance on an extensive set of
test problems in both special and general relativity. Our new GRMHD code has
proven to be accurate in second order and has successfully passed with all
tests performed, including highly relativistic and magnetized cases in both
special and general relativity.


title:
The cosmic star formation rate evolution from z=5 to z=0 from the VIMOS
  VLT Deep Survey

abstract:
  We present the evolution of the comoving SFR density in the redshift range 0
< z < 5 using the first epoch data release of the VVDS, that is 11564 spectra
selected at I_AB=24 over 2200 arcmin^2 in two fields of view, the VVDS-0226-04
and the VVDS-CDFS-0332-27, and the cosmological parameters (Omega_M, Omega_L,
h)=(0.3, 0.7, 0.7). We study the multi-wavelength non dust-corrected luminosity
densities at 0 < z < 2 from the rest-frame FUV to the optical passbands, and
the rest-frame 1500A luminosity functions and densities at 2.7 < z < 5. They
evolve from z=1.2 to 0.05 according to (1+z)^{x} with x = 2.05, 1.94, 1.92,
1.14, 0.73, 0.42, 0.30 in the FUV-1500, NUV-2800, U-3600, B-4400, V-5500,
R-6500, and I-7900 passbands, respectively. From z = 1.2 to 0.2 the B-band
density for the irregular-like galaxies decreases markedly by a factor 3.5
while it increases by a factor 1.7 for the elliptical-like galaxies. We
identify several SFR periods; from z = 5 to 3.4 the FUV-band density increases
by at most 0.5dex, from z=3.4 to 1.2 it decreases by 0.08dex, from z=1.2 to
0.05 it declines steadily by 0.6dex. For the most luminous M_AB(1500) < -21
galaxies the FUV-band density drops by 2dex from z = 3.9 to 1.2, and for the
intermediate -21 < M_AB(1500) < -20 galaxies it drops by 2dex from z = 0.2 to
0. Comparing with dust corrected surveys, at 0.4 < z < 2 the FUV seems obscured
by a constant factor of ~1.8-2 mag, while at z < 0.5 it seems progressively
less obscured by up to ~0.9-1 mag when the dust-deficient early-type population
is increasingly dominating the B-band density. The VVDS results agree with a
downsizing picture where the most luminous sources cease to efficiently produce
new stars 12 Gyrs ago (at z~4), while intermediate luminosity sources keep
producing stars until 2.5 Gyrs ago (at z~0.2).(abridged)


title: The Electron Temperature Gradient in the Galactic Disk

abstract:
  We derive the electron temperature gradient in the Galactic disk using a
sample of HII regions that spans Galactocentric distances 0--17 kpc. The
electron temperature was calculated using high precision radio recombination
line and continuum observations for more than 100 HII regions. Nebular
Galactocentric distances were calculated in a consistent manner using the
radial velocities measured by our radio recombination line survey. The large
number of nebulae widely distributed over the Galactic disk together with the
uniformity of our data provide a secure estimate of the present electron
temperature gradient in the Milky Way. Because metals are the main coolants in
the photoionized gas, the electron temperature along the Galactic disk should
be directly related to the distribution of heavy elements in the Milky Way. Our
best estimate of the electron temperature gradient is derived from a sample of
76 sources for which we have the highest quality data. The present gradient in
electron temperature has a minimum at the Galactic Center and rises at a rate
of 287 +/- 46 K/kpc. There are no significant variations in the value of the
gradient as a function of Galactocentric radius or azimuth. The scatter we find
in the HII region electron temperatures at a given Galactocentric radius is not
due to observational error, but rather to intrinsic fluctuations in these
temperatures which are almost certainly due to fluctuations in the nebular
heavy element abundances. Comparing the HII region gradient with the much
steeper gradient found for planetary nebulae suggests that the electron
temperature gradient evolves with time, becoming flatter as a consequence of
the chemical evolution of the Milky Way's disk.


title: Stability Properties of Magnetic Tower Jets

abstract:
  Stability properties of ``magnetic tower'' jets propagating in the
gravitationally stratified background have been examined by performing
three-dimensional magnetohydrodynamic simulations. The current-carrying,
Poynting flux-dominated magnetic tower jet, which possesses a highly wound
helical magnetic field, is subject to the current-driven instability (CDI). We
find that, under general physical conditions including small perturbations in
the initial background profiles, the propagating magnetic tower jets develop
the non-axisymmetric, $m=1$ kink mode of the CDI. The kink mode grows on the
local Alfv\'en crossing time scale. In addition, two types of kink modes appear
in the system. At the central region where external thermal pressure
confinement is strong, only the internal kink mode is excited and will grow. A
large distance away from the central region where the external thermal pressure
becomes low, the external kink mode is observed. As a result, the exterior of
magnetic tower jets will be deformed into a large-scale wiggled structure. We
also discuss extensively the different physical processes that contribute to
the overall stability properties of the magnetic tower jets. Specifically, when
the jet propagates in an initially unperturbed background, we find that they
can survive the kink mode beyond the point predicted by the well-known
Kruskal-Shafranov (K-S) criterion. The stabilization in this case comes mainly
from the dynamical relaxation of magnetic twists during the propagation of
magnetic towers; the magnetic pitch is reduced and the corresponding K-S
critical wavelength becomes longer as the tower jet proceeds. Furthermore, we
show that the pressure-driven and Kelvin-Helmholtz instabilities do not occur
in the magnetic tower jets.


title:
New Galactic Wolf-Rayet stars, and candidates. An annex to The VIIth
  Catalogue of Galactic Wolf-Rayet Stars

abstract:
  This paper gathers, from the literature and private communication, 72 new
Galactic Population I Wolf-Rayet stars and 17 candidate WCLd stars, recognized
and/or discovered after the publication of The VIIth Catalogue of Galactic
Wolf-Rayet Stars. This brings the total number of known Galactic Wolf-Rayet
stars to 298, of which 24 (8%) are in open cluster Westerlund 1, and 60 (20%)
are in open clusters near the Galactic Center.


title: The optical spectral slope variability of 17 blazars

abstract:
  Many quasi-simultaneous optical observations of 17 blazars are obtained from
previous papers published over the last 19 years in order to investigate the
spectral slope variability and understand the radiation mechanism of blazars.
The long-period dereddened optical spectral slopes are calculated. We analyse
the average spectral slope distribution, which suggests that the spectra of
flat spectrum radio quasars (FSRQs) and high energy peaked BL Lac objects
(HBLs) are probably deformed by other emission components. The average spectral
slopes of low energy peaked BL Lac objects(LBLs), which scatter around 1.5,
show a good accordance with the synchrotron self-Compton (SSC) loss-dominated
model. We present and discuss the variability between the spectral slope and
optical luminosity. The spectra of all HBLs and LBLs get flatter when they turn
brighter, while for FSRQs this trend does not exist or may even be reversed.
This phenomenon may imply that there is a thermal contribution to the optical
spectrum for FSRQs. For the FSRQ 1156+295, there is a hint that the slope gets
flatter at both the brightest and faintest states. Our result shows that three
subclasses locate in different regions in the pattern of slope variability
indicator versus average spectral slope. The relativistic jet mechanism is
supported by the significant correlation between the optical Doppler factor and
the average spectral slope.


title:
The Southern Galactic Plane Survey: Polarized Radio Continuum
  Observations and Analysis

abstract:
  The Southern Galactic Plane Survey (SGPS) is a radio survey in the 21 cm H I
line and in 1.4 GHz full-polarization continuum, observed with the Australia
Telescope Compact Array and the Parkes 64m single dish telescope. The survey
spans a Galactic longitude of 253 deg < l < 358 deg and a latitude of |b| < 1
deg at a resolution of 100 arcsec and a sensitivity below 1 mJy/beam. This
paper presents interferometer only polarized continuum survey data and
describes the data taking, analysis processes and data products. The primary
data products are the four Stokes parameters I, Q, U, and V in 25 overlapping
fields of 5.5 deg by 2 deg, from which polarized intensity, polarization angle
and rotation measure are calculated. We describe the effects of missing short
spacings, and discuss the importance of the polarized continuum data in the
SGPS for studies of fluctuations and turbulence in the ionized interstellar
medium and for studying the strength and structure of the Galactic magnetic
field.


title:
Implication of Existence of Hybrid stars and Theoretical Expectation of
  Submillisecond Pulsars

abstract:
  We derive the bulk viscous damping timescale of hybrid stars, neutron stars
with quark matter core. The r-mode instability windows of the stars show that
the theoretical results are consistent with the rapid rotation pulsar data,
which may give an indication for the existence of quark matter in the interior
of neutron stars. Hybrid stars instead of neutron or strange stars may lead to
submillisecond pulsars.


title:
Comparison between Windowed FFT and Hilbert-Huang Transform for
  Analyzing Time Series with Poissonian Fluctuations: A Case Study

abstract:
  Hilbert-Huang Transform (HHT) is a novel data analysis technique for
nonlinear and non-stationary data. We present a time-frequency analysis of both
simulated light curves and an X-ray burst from the X-ray burster 4U 1702-429
with both the HHT and the Windowed Fast Fourier Transform (WFFT) methods. Our
results show that the HHT method has failed in all cases for light curves with
Poissonian fluctuations which are typical for all photon counting instruments
used in astronomy, whereas the WFFT method can sensitively detect the periodic
signals in the presence of Poissonian fluctuations; the only drawback of the
WFFT method is that it cannot detect sharp frequency variations accurately.


title:
Upper bounds on the low-frequency stochastic gravitational wave
  background from pulsar timing observations: current limits and future
  prospects

abstract:
  Using a statistically rigorous analysis method, we place limits on the
existence of an isotropic stochastic gravitational wave background using pulsar
timing observations. We consider backgrounds whose characteristic strain
spectra may be described as a power-law dependence with frequency. Such
backgrounds include an astrophysical background produced by coalescing
supermassive black-hole binary systems and cosmological backgrounds due to
relic gravitational waves and cosmic strings. Using the best available data, we
obtain an upper limit on the energy density per unit logarithmic frequency
interval of \Omega^{\rm SMBH}_g(1/8yr) h^2 <= 1.9 x 10^{-8} for an
astrophysical background which is five times more stringent than the earlier
Kaspi et al. (1994) limit of 1.1 x 10^{-7}. We also provide limits on a
background due to relic gravitational waves and cosmic strings of \Omega^{\rm
relic}_g(1/8yr) h^2 <= 2.0 x 10^{-8} and \Omega^{\rm cs}_g(1/8yr) h^2 <= 1.9 x
10^{-8} respectively. All of the quoted upper limits correspond to a 0.1% false
alarm rate together with a 95% detection rate. We discuss the physical
implications of these results and highlight the future possibilities of the
Parkes Pulsar Timing Array project. We find that our current results can 1)
constrain the merger rate of supermassive binary black hole systems at high red
shift, 2) rule out some relationships between the black hole mass and the
galactic halo mass, 3) constrain the rate of expansion in the inflationary era
and 4) provide an upper bound on the dimensionless tension of a cosmic string
background.


title:
Large Misalignment between Stellar Bar and Dust Pattern in NGC 3488
  Revealed by Spitzer and SDSS

abstract:
  A large position angle misalignment between the stellar bar and the
distribution of dust in the late-type barred spiral NGC 3488 was discovered,
using mid-infrared images from the Spitzer Space Telescope and optical images
from the Sloan Digital Sky Survey (SDSS). The angle between the bar and dust
patterns was measured to be 25+-2deg, larger than most of the misalignments
found previously in barred systems based on Ha or HI/CO observations. The
stellar bar is bright at optical and 3.6um, while the dust pattern is more
prominent in the 8um band but also shows up in the SDSS u and g-band images,
suggesting a rich interstellar medium environment harboring ongoing star
formation. This angular misalignment is unlikely to have been caused by
spontaneous bar formation. We suggest that the stellar bar and the dust pattern
may have different formation histories, and that the large misalignment was
triggered by a tidal interaction with a small companion. A statistical analysis
of a large sample of nearby galaxies with archival Spitzer data indicates that
bar structure such as that seen in NGC 3488 is quite rare in the local
Universe.


title: The coronal Ne/O abundance of alpha Centauri

abstract:
  Recent improvements in the modeling of solar convection and line formation
led to downward revisions of the solar photospheric abundances of the lighter
elements, which in turn led to changes in the radiative opacity of the solar
interior and hence to conflicts with the solar convection zone depth as
inferred from helioseismic oscillation frequencies. An increase of the solar
Ne/O abundance to values as observed for nearby stars has been proposed as a
solution. Because of the absence of strong neon lines in the optical, neon
abundances are difficult to measure and the correct solar and stellar Ne/O
abundances are currently hotly debated. Based on X-ray spectra obtained with
XMM-Newton, we determine a reference value of Ne/O for the inactive, solar-like
star alpha Cen (primarily alpha Cen B, which is the dominant component in
X-rays), with three independent, line-based methods, using differential
emission measure reconstruction and an emission measure-independent method. Our
results indicate a value of approx. 0.28 for Ne/O in alpha Cen, approximately
twice the value measured for the Sun, but still below the average value
obtained for other stars. The low Ne/O abundance of the Sun is peculiar when
compared to alpha Cen and other stars; our results emphasize the necessity to
obtain more and accurate Ne/O abundance measurements of low activity stars.


title:
Evolution of the Luminosity Function, Star Formation Rate, Morphology
  and Size of Star-forming Galaxies Selected at Rest-frame 1500A and 2800A

abstract:
  Using the multiwavelength photometric and spectroscopic data covering the
CDF-S obtained within the GOODS, we investigate the rest-frame UV properties of
galaxies to z~2.2, including the evolution of the luminosity function, the
luminosity density, star formation rate (SFR) and galaxy morphology. We find a
significant brightening (~ 1 mag) in the rest-frame 2800A characteristic
magnitude (M*) over the redshift range 0.3<z<1.7 and no evolution at higher
redshifts. The rest-frame 2800A luminosity density shows an increase by a
factor ~4 to z~2.2. We estimate the SFR to z~2.2 from the 1500A and 2800A
luminosities. The SFR derived from the 2800A luminosity density is almost
factor two higher than that derived from the 1500A luminosities. Attributing
this to differential dust extinction, we find that an E(B-V)=0.20 results in
the same extinction corrected SFR from both 1500A and 2800A luminosities. We
investigate the morphological composition of our sample by fitting Sersic
profiles to the galaxy images at a fixed rest-frame wavelength of 2800A at
0.5<z<2.2. We find that the fraction of apparently bulge-dominated galaxies
(Sersic index n>2.5) increases from ~10% at z~0.5 to ~30% at z~2.2. At the same
time, we note that galaxies get bluer at increasing redshift. This suggests a
scenario where an increased fraction of the star formation takes place in
bulge-dominated systems at high redshift. This could be the evidence that the
present day ellipticals are a result of assembly (i.e., mergers) of galaxies at
z>1. Finally, we find that galaxy sizes for a luminosity selected sample
evolves as (1+z)^{-1.1} between redshifts z=2.2 and z=1.1. This is consistent
with previous measurements and suggests a similar evolution over the redshift
range 0 < z < 6.


title:
Do Ultraluminous X-ray Sources Really Contain Intermediate-mass Black
  Holes?

abstract:
  An open question remains whether Ultraluminous X-ray Sources (ULXs) really
contain intermediate-mass black holes (IMBHs). We carefully investigated the
XMM-Newton EPIC spectra of the four ULXs that were claimed to be strong
candidates of IMBHs by several authors. We first tried fitting by the standard
spectral model of disk blackbody (DBB) + power-law (PL), finding good fits to
all of the data, in agreement with others. We, however, found that the PL
component dominates the DBB component at $\sim$ 0.3 to 10 keV. Thus, the black
hole parameters derived solely from the minor DBB component are questionable.
Next, we tried to fit the same data by the ``$p$-free disk model'' without the
PL component, assuming the effective temperature profile of $T_{\rm eff}
\propto r^{-p}$ where $r$ is the disk radius. Interestingly, in spite of one
less free model parameters, we obtained similarly good fits with much higher
innermost disk temperatures, $1.8 < kT_{\rm in} < 3.2$ keV. More importantly,
we obtained $p \sim 0.5$, just the value predicted by the slim (super-critical)
disk theory, rather than $p = 0.75$ that is expected from the standard disk
model. The estimated black hole masses from the $p$-free disk model are much
smaller; $M\ltsim 40 M_\odot$. Furthermore, we applied a more sophisticated
slim disk model by Kawaguchi (2003, ApJ, 593,69), and obtained good fits with
roughly consistent black hole masses. We thus conclude that the central engines
of these ULXs are super-critical accretion flows to stellar-mass black holes.


title: Variation of the cluster luminosity function across the disk of M51

abstract:
  We study the luminosity function (LF) of the star clusters in M51. Comparing
the observed LF with the LF resulting from artificial cluster populations
suggests that there exists an upper mass limit for clusters and that this limit
and/or the cluster disruption varies with galactocentric distance.


title:
Suppression of the large scale curvature perturbation by interacting
  fluids

abstract:
  The large-scale dynamics of a two-fluid system with a time dependent
interaction is studied analytically and numerically. We show how a rapid
transition can significantly suppress the large-scale curvature perturbation
and present approximative formulae for estimating the effect. By comparing to
numerical results, we study the applicability of the approximation and find
good agreement with exact calculations.


title:
The fate of spiral galaxies in clusters: the star formation history of
  the anemic Virgo cluster galaxy NGC 4569

abstract:
  We present a new method for studying the star formation history of late-type,
cluster galaxies undergoing gas starvation or a ram-pressure stripping event by
combining bidimensional multifrequency observations with multi-zones models of
galactic chemical and spectrophotometricevolution. This method is applied to
the Virgo cluster anemic galaxy NGC 4569. We extract radial profiles from
recently obtained UV GALEX images at 1530 and 2310 A, from visible and near-IR
narrow (Halpha) and broad band images at different wavelengths (u, B, g, V, r,
i, z, J, H, K), from Spitzer IRAC and MIPS images and from atomic and molecular
gas maps. The model in the absence of interaction (characterized by its
rotation velocity and spin parameter) is constrained by the unperturbed H band
light profile and by the Halpha rotation curve. We can reconstruct the observed
total-gas radial-density profile and the light surface-brightness profiles at
all wavelengths in a ram-pressure stripping scenario by making simple
assumptions about the gas removal process and the orbit of NGC 4569 inside the
cluster. The observed profiles cannot be reproduced by simply stopping gas
infall, thus mimicing starvation. Gas removal is required, which is more
efficient in the outer disk, inducing a radial quenching in the star formation
activity, as observed and reproduced by the model. This observational result,
consistent with theoretical predictions that a galaxy-cluster IGM interaction
is able to modify structural disk parameters without gravitational
perturbations, is discussed in the framework of the origin of lenticulars in
clusters.


title: Infrared Constrains on AGN Tori Models

abstract:
  This work focuses on the properties of dusty tori in active galactic nuclei
(AGN) derived from the comparison of SDSS type 1 quasars with mid-Infrared
(MIR) counterparts and a new, detailed torus model. The infrared data were
taken by the Spitzer Wide-area InfraRed Extragalactic (SWIRE) Survey. Basic
model parameters are constraint, such as the density law of the graphite and
silicate grains, the torus size and its opening angle. A whole variety of
optical depths is supported. The favoured models are those with decreasing
density with distance from the centre, while there is no clear tendency as to
the covering factor, i.e. small, medium and large covering factors are almost
equally distributed. Based on the models that better describe the observed
SEDs, properties such as the accretion luminosity, the mass of dust, the inner
to outer radius ratio and the hydrogen column density are computed. The
properties of the tori, as derived fitting the observed SEDs, are independent
of the redshift, once observational biases are taken into account.


title: HI in circumstellar environments

abstract:
  We present new results of a spectroscopic survey of circumstellar HI in the
direction of evolved stars made with the Nancay Radiotelescope. The HI line at
21 cm has been detected in the circumstellar shells of a variety of evolved
stars: AGB stars, oxygen-rich and carbon-rich, Semi-Regular and Miras, and
Planetary Nebulae. The emissions are generally spatially resolved, i.e. larger
than 4', indicating shell sizes of the order of 1 pc which opens the
possibility to trace the history of mass loss over the past ~ 10^4-10^5 years.
The line-profiles are sometimes composite. The individual components have
generally a quasi-Gaussian shape; in particular they seldom show the
double-horn profile that would be expected from the spatially resolved
optically thin emission of a uniformly expanding shell. This probably implies
that the expansion velocity decreases outwards in the external shells (0.1-1
pc) of these evolved stars. The HI line-profiles do not necessarily match those
of the CO rotational lines. Furthermore, the centroid velocities do not always
agree with those measured in the CO lines and/or the stellar radial velocities.
The HI emissions may also be shifted in position with respect to the central
stars. Without excluding the possibility of asymmetric mass ejection, we
suggest that these two effects could also be related to a non-isotropic
interaction with the local interstellar medium. HI was detected in emission
towards several sources (rho Per, alpha Her, delta^2 Lyr, U CMi) that otherwise
have not been detected in any radio lines. Conversely it was not detected in
the two oxygen-rich stars with substantial mass-loss rate, NML Tau and WX Psc,
possibly because these sources are young with hydrogen in molecular form,
and/or because the temperature of the circumstellar HI gas is very low (< 5 K).


title:
Static and Dynamic Modeling of a Solar Active Region. I: Soft X-Ray
  Emission

abstract:
  Recent simulations of solar active regions have shown that it is possible to
reproduce both the total intensity and the general morphology of the high
temperature emission observed at soft X-ray wavelengths using static heating
models. There is ample observational evidence, however, that the solar corona
is highly variable, indicating a significant role for dynamical processes in
coronal heating. Because they are computationally demanding, full hydrodynamic
simulations of solar active regions have not been considered previously. In
this paper we make first application of an impulsive heating model to the
simulation of an entire active region,
  AR8156 observed on 1998 February 16. We model this region by coupling
potential field extrapolations to full solutions of the time-dependent
hydrodynamic loop equations. To make the problem more tractable we begin with a
static heating model that reproduces the emission observed in 4 different
\textit{Yohkoh} Soft X-Ray Telescope
  (SXT) filters and consider dynamical heating scenarios that yield
time-averaged SXT intensities that are consistent with the static case. We find
that it is possible to reproduce the total observed soft X-ray emission in all
of the SXT filters with a dynamical heating model, indicating that nanoflare
heating is consistent with the observational properties of the high temperature
solar corona.


title:
The Mid-IR Properties of Starburst Galaxies from Spitzer-IRS
  Spectroscopy

abstract:
  We present 5-38um mid-infrared spectra at a spectral resolution of R~65-130
of a large sample of 22 starburst nuclei taken with the Infrared Spectrograph
IRS on board the Spitzer Space Telescope. The spectra show a vast range in
starburst SEDs. The silicate absorption ranges from essentially no absorption
to heavily obscured systems with an optical depth of tau(9.8um)~5. The spectral
slopes can be used to discriminate between starburst and AGN powered sources.
The monochromatic continuum fluxes at 15um and 30um enable a remarkably
accurate estimate of the total infrared luminosity of the starburst. We find
that the PAH equivalent width is independent of the total starburst luminosity
L_IR as both continuum and PAH feature scale proportionally. However, the
luminosity of the 6.2um feature scales with L_IR and can be used to approximate
the total infrared luminosity of the starburst. Although our starburst sample
covers about a factor of ten difference in the [NeIII]/[NeII] ratio, we found
no systematic correlation between the radiation field hardness and the PAH
equivalent width or the 7.7um/11.3um PAH ratio. These results are based on
spatially integrated diagnostics over an entire starburst region, and local
variations may be ``averaged out''. It is presumably due to this effect that
unresolved starburst nuclei with significantly different global properties
appear spectrally as rather similar members of one class of objects.


title: Collisional dust avalanches in debris discs

abstract:
  We quantitatively investigate how collisional avalanches may developin debris
discs as the result of the initial break-up of a planetesimal or comet-like
object, triggering a collisional chain reaction due to outward escaping small
dust grains. We use a specifically developed numerical code that follows both
the spatial distribution of the dust grains and the evolution of their
size-frequency distribution due to collisions. We investigate how strongly
avalanche propagation depends on different parameters (e.g., amount of dust
released in the initial break-up, collisional properties of dust grains and
their distribution in the disc). Our simulations show that avalanches evolve on
timescales of ~1000 years, propagating outwards following a spiral-like
pattern, and that their amplitude exponentially depends on the number density
of dust grains in the system. We estimate a probability for witnessing an
avalanche event as a function of disc densities, for a gas-free case around an
A-type star, and find that features created by avalanche propagation can lead
to observable asymmetries for dusty systems with a beta Pictoris-like dust
content or higher. Characteristic observable features include: (i) a brightness
asymmetry of the two sides for a disc viewed edge-on, and (ii) a one-armed open
spiral or a lumpy structure in the case of face-on orientation. A possible
system in which avalanche-induced structures might have been observed is the
edge-on seen debris disc around HD32297, which displays a strong luminosity
difference between its two sides.


title:
SiO and CH3CCH abundances and dust emission in high-mass star-forming
  cores

abstract:
  Aims. The main goal of the present study is to determine the fractional SiO
abundance in high-mass star-forming cores, and to investigate its dependence on
the physical conditions. In this way we wish to provide constraints on the
chemistry models concerning the formation of SiO in the gas phase or via grain
mantle evaporation. The work addresses also CH3CCH chemistry as the kinetic
temperature is determined using this molecule.
  Methods. We estimate the physical conditions of 15 high-mass star-forming
cores and derive the fractional SiO and CH3CCH abundances in them by using
spectral line and dust continuum observations with the SEST.
  Results. The kinetic temperatures as derived from CH3CCH range from 25 to 39
K. The SiO emission regions are extended and typically half of the integrated
line emission comes from the velocity range traced out by CH3CCH emission. The
upper limit of SiO abundance in this 'quiescent' gas component is ~10^-10. The
average CH3CCH abundance is about 7 x 10^-9. It shows a shallow, positive
correlation with the temperature, whereas SiO shows the opposite tendency.
  Conclusions. We suggest that the high CH3CCH abundance and its possible
increase when the clouds get warmer is related to the intensified desorption of
the chemical precursors of the molecule from grain surfaces. In contrast, the
observed tendency of SiO does not support the idea that the evaporation of
Si-containing species from the grain mantles would be important, and it
contradicts with the models where neutral reactions with activation barriers
dominate the SiO production. A possible explanation for the decrease is that
warmer cores represent more evolved stages of core evolution with fewer
high-velocity shocks and thus less efficient SiO replenishment.


title:
A U-band survey of brown dwarfs in the Taurus Molecular Cloud with the
  XMM-Newton Optical/UV Monitor

abstract:
  We aim to characterize the U-band variability of young brown dwarfs in the
Taurus Molecular Cloud and discuss its origin. We used the XMM-Newton Extended
Survey of the Taurus Molecular Cloud, where a sample of 11 young bona fide
brown dwarfs (spectral type later than M6) were observed simultaneously in
X-rays with XMM-Newton and in the U-band with the XMM-Newton Optical/UV Monitor
(OM). We obtained upper limits to the U-band emission of 10 brown dwarfs
(U>19.6-20.6 mag), whereas 2MASSJ04141188+2811535 was detected in the U-band.
Remarkably, the magnitude of this brown dwarf increased regularly from U~19.5
mag at the beginning of the observation, peaked 6h later at U~18.4 mag, and
then decreased to U~18.65 mag in the next 2h. The first OM U-band measurement
is consistent with the quiescent level observed about one year later thanks to
ground follow-up observations. This brown dwarf was not detected in X-rays by
XMM-Newton during the OM observation. We discuss the possible sources of U-band
variability for this young brown dwarf, namely a magnetic flare, non-steady
accretion onto the substellar surface, and rotational modulation of a hot spot.
We conclude that this event is related to accretion from a circumsubstellar
disk, where the mass accretion rate was about a factor of 3 higher than during
the quiescent level.


title:
Probing Modified Gravity by Combining Supernovae and Galaxy Cluster
  Surveys

abstract:
  Possible explanations of the observed accelerated expansion of the Universe
are the introduction of a dark energy component or the modifications of gravity
at large distances. A particular difference between these scenarios is the
dynamics of the growth of structures. The redshift distribution of galaxy
clusters will probe this growth of structures with large precision. Here we
will investigate how proposed galaxy cluster surveys will allow one to
distinguish the modified gravity scenarios from dark energy models. We find
that cluster counts can distinguish the Dvali-Gabadadze-Porrati model from a
dark energy model, which has the same background evolution, as long as the
amplitude of the primordial power spectrum is constrained by a CMB experiment
like Planck. In order to achieve this, only a couple of hundred clusters in
bins of width Delta-z = 0.1 are required. This should be easily achievable with
forthcoming Sunyaev-Zel'dovich cluster counts, such as the South Pole Telescope
in conjunction with the Dark Energy Survey.


title:
Synthetic properties of bright metal-poor variables. I. "Anomalous"
  Cepheids

abstract:
  We present new grids of evolutionary models for the so-colled ``Anomalous''
Cepheids (ACs), adopting Z=0.0001 and various assumptions on the progenitor
mass and mass-loss efficiency. These computations are combined with the results
of our previous set of pulsation models and used to build synthetic populations
of the predicted pulsators as well as to provide a Mass-Luminosity relation in
the absence of mass-loss. We investigate the effect of mass-loss on the
predicted boundaries of the instability strip and we find that the only
significant dependence occurs in the Period-Magnitude plane, where the
synthetic distribution of the pulsators is, on average, brighter by about 0.1
mag than the one in absence of mass-loss. Tight Period-Magnitude relations are
derived in the K band for both fundamental and first overtone pulsators,
providing a useful tool for distance evaluations with an intrinsic uncertainty
of about 0.15 mag, which decreases to about 0.04 mag if the mass term is taken
into account. The constraints provided by the evolutionary models are used to
derive evolutionary (i.e, mass-independent) Period-Magnitude-Color relations
which provide distance determinations with a formal uncertainty of the order of
about 0.1 mag, once the intrinsic colors are well known. We also use model
computations from the literature to investigate the effect of metal content
both on the instability strip and on the evolutionary Period-Magnitude-Color
relations. Finally, we compare our theoretical predictions with observed
variables and we confirm that a secure identification of actual ACs requires
the simultaneous information on period, magnitude and color, that also provide
constraints on the pulsation mode.


title: A population of high-redshift type-2 quasars-II. Radio Properties

abstract:
  We present multi-frequency radio observations of a sample of z~2 obscured
(type-2) quasars in the Spitzer extragalactic First Look Survey area. We
combine the public data at 1.4 GHz, used in the selection of these sources,
with new observations at 610 MHz (GMRT) and at 4.9 GHz (VLA). We find the
sample includes sources with steep, flat and gigahertz-peaked spectra. There
are no strong correlations between the presence or absence of emission lines in
the optical spectra and the radio spectral properties of the sample. However,
there are no secure flat-spectrum type-2 quasars with narrow emission lines
which would be problematic for unified schemes. Most of the population have
straight radio spectra with spectral index alpha~1 as is expected for
developed, potentially FRI-like, jets in which continous injection of
relativistic electrons is accompanied by inverse-Compton losses against the
cosmic microwave background.


title: Can Electric Charges and Currents Survive in an Inhomogeneous Universe?

abstract:
  Although observations point to the neutrality and lack of currents on large
scales in the universe, many mechanisms are known that can generate charges or
currents during the early universe. We examine the question of survivability of
relic charges and currents in a realistic model of the universe. We show that
the dynamics of cosmological perturbations drive the universe to become
electrically neutral and current-free to a high degree of accuracy on all
scales, regardless of initial conditions. We find that charges are efficiently
driven away in a time small compared to the Hubble time for temperatures 100
GeV > T > 1 eV, while the same is true for currents at all temperatures T > 1
eV. The forced neutrality relaxes constraints on the generation of an electric
charge in the early universe, while the forced erasure of currents disfavors
many mechanisms for the early origins of large-scale magnetic fields.


title: Accretion Rates in Herbig Ae stars

abstract:
  Accretion rates from disks around pre-main sequence stars are of importance
for our understanding of planetary formation and disk evolution. We provide in
this paper estimates of the mass accretion rates in the disks around a large
sample of Herbig Ae stars. We obtained medium resolution 2 micron spectra and
used the results to compute values of Macc from the measured luminosity of the
Br_gamma emission line, using a well established correlation between
L(Br_gamma) and the accretion luminosity Lacc. We find that 80% of the stars,
all of which have evidence of an associated circumstellar disk, are accreting
matter, with rates 3x10^{-9} < Macc} < 10^{-6} Msun/yr; for 7 objects, 6 of
which are located on the ZAMS in the HR diagram, we do not detect any line
emission. Few HAe stars (25%) have Macc>10^{-7} Msun/yr. In most HAe stars the
accretion rate is sufficiently low that the gas in the inner disk, inside the
dust evaporation radius, is optically thin and does not prevent the formation
of a puffed-up rim, where dust is directly exposed to the stellar radiation.
When compared to the Macc values found for lower-mass stars in the star forming
regions Taurus and Ophiuchus, HAe stars have on average higher accretion rates
than solar-mass stars; however, there is a lack of very strong accretors among
them, probably due to the fact that they are on average older.


title: Polarized Emission from Interstellar Dust

abstract:
  Observations of far-infrared (FIR) and submillimeter (SMM) polarized emission
are used to study magnetic fields and dust grains in dense regions of the
interstellar medium (ISM). These observations place constraints on models of
molecular clouds, star-formation, grain alignment mechanisms, and grain size,
shape, and composition. The FIR/SMM polarization is strongly dependent on
wavelength. We have attributed this wavelength dependence to sampling different
grain populations at different temperatures. To date, most observations of
polarized emission have been in the densest regions of the ISM. Extending these
observations to regions of the diffuse ISM, and to microwave frequencies, will
provide additional tests of grain and alignment models.
  An understanding of polarized microwave emission from dust is key to an
accurate measurement of the polarization of the cosmic microwave background.
The microwave polarization spectrum will put limits on the contributions to
polarized emission from spinning dust and vibrating magnetic dust.


title:
Heating and Non-thermal Particle Acceleration in Relativistic,
  Transverse Magnetosonic Shock Waves in Proton-Electron-Positron Plasmas

abstract:
  We report the results of 1D particle-in-cell simulations of ultrarelativistic
shock waves in proton-electron-positron plasmas. We consider magnetized shock
waves, in which the upstream medium carries a large scale magnetic field,
directed transverse to the flow. Relativistic cyclotron instability of each
species as the incoming particles encounter the increasing magnetic field
within the shock front provides the basic plasma heating mechanism. The most
significant new results come from simulations with mass ratio $m_p/m_\pm =
100$. We show that if the protons provide a sufficiently large fraction of the
upstream flow energy density (including particle kinetic energy and Poynting
flux), a substantial fraction of the shock heating goes into the formation of
suprathermal power-law spectra of pairs. Cyclotron absorption by the pairs of
the high harmonic ion cyclotron waves, emitted by the protons, provides the
non-thermal acceleration mechanism. As the proton fraction increases, the
non-thermal efficiency increases and the pairs' power-law spectra harden.
  We suggest that the varying power law spectra observed in synchrotron sources
powered by magnetized winds and jets might reflect the correlation of the
proton to pair content enforced by the underlying electrodynamics of these
sources' outflows, and that the observed correlation between the X-ray spectra
of rotation powered pulsars with the X-ray spectra of their nebulae might
reflect the same correlation.


title: Thermal and Bulk Comptonization in Accretion-Powered X-Ray Pulsars

abstract:
  We develop a new theoretical model for the spectral formation process in
accretion-powered X-ray pulsars based on a detailed treatment of the bulk and
thermal Comptonization occurring in the accreting, shocked gas. A rigorous
eigenfunction expansion method is employed to obtain the analytical solution
for the Green's function describing the scattering of radiation injected into
the column from a monochromatic source located at an arbitrary height above the
stellar surface. The emergent spectrum is calculated by convolving the Green's
function with source terms corresponding to bremsstrahlung, cyclotron, and
blackbody emission. The energization of the photons in the shock, combined with
cyclotron absorption, naturally produces an X-ray spectrum with a relatively
flat continuum shape and a high-energy quasi-exponential cutoff. We demonstrate
that the new theory successfully reproduces the phase-averaged spectra of the
bright pulsars Her X-1, LMC X-4, and Cen X-3. In these luminous sources, it is
shown that the emergent spectra are dominated by Comptonized bremsstrahlung
emission.


title:
Massive Young Stellar Objects in the Large Magellanic Cloud: water
  masers and ESO-VLT 3-4 micron spectroscopy

abstract:
  We investigate the conditions of star formation in the Large Magellanic
Cloud. We have conducted a survey for water maser emission arising from massive
young stellar objects in the 30 Doradus region (N 157) and several other H II
regions in the Large Magellanic Cloud (N 105A, N 113 and N 160A). We have
identified a new maser source in 30 Dor at the systemic velocity of the LMC. We
have obtained 3-4 micron spectra, with the ESO Very Large Telescope, of two
candidate young stellar objects. N 105A IRS1 shows H recombination line
emission and its Spectral Energy Distribution (SED) and mid-infrared colours
are consistent with a massive young star ionising the molecular cloud. N 157B
IRS1 is identified as an embedded young object, based on its SED and a
tentative detection of water ice. The data on these four H II regions are
combined with mid-infrared archival images from the Spitzer Space Telescope to
study the location and nature of the embedded massive young stellar objects and
signatures of stellar feedback. Our analysis of 30 Dor, N 113 and N 160A
confirms the picture that the feedback from the massive O and B-type stars,
which creates the H II regions, also triggers further star formation on the
interfaces of the ionised gas and the surrounding molecular cloud. Although in
the dense cloud N 105A star formation seems to occur without evidence of
massive star feedback, the general conditions in the LMC seem favourable for
sequential star formation as a result of feedback. In an appendix we present
water maser observations of the galactic red giants R Doradus and W Hydrae.


title:
Chandra Observation of the Interaction of the Radio Source and Cooling
  Core in Abell 2063

abstract:
  We present the results of a Chandra observation of the cooling core cluster
Abell 2063. Spectral analysis shows that there is cool gas (2 keV) associated
with the cluster core, which is more than a factor of 2 cooler than the outer
cluster gas (4.1 keV). There also is spectral evidence for a weak cooling flow,
Mdot ~ 20 Msun/yr. The cluster exhibits a complex structure in the center that
consists of several bright knots of emission, a depression in the emission to
the north of the center of the cluster, and a shell of emission surrounding it.
The depression in the X-ray emission is coincident with the position of the
north-eastern radio lobe of the radio source associated with the
cluster-central galaxy. The shell surrounding this region appears to be hotter,
which may be the result of a shock that has been driven into the gas by the
radio source. The power output of the radio source appears to be sufficient to
offset the cooling flow, and heating of the gas through shocks is a possible
explanation of how the energy transfer is established.


title:
Relating Diffusion Properties of Cosmic-Ray Electrons to Star Formation
  Activity within Normal Galaxies

abstract:
  Using data obtained as part of the {\it Spitzer} Infrared Nearby Galaxies
Survey (SINGS; Kennicutt et al. 2003) and WSRT-SINGS radio continuum survey
(Braun et al. 2006), we study the effects of star-formation activity on the
far-infrared (FIR)--radio correlation {\it within} galaxies. This is done by
testing a phenomenological model for the correlation, which describes the radio
image as a smeared version of the FIR image. We find that this description
works particularly well for galaxies with higher infrared surface brightnesses,
yielding best-fit smoothing scale-lengths of a few hundred parsecs,
substantially shorter than those for lower surface brightness galaxies. We
interpret this result to suggest that galaxies with higher disk averaged star
formation rates have had a recent episode of enhanced star formation and are
characterized by a higher fraction of young cosmic-ray (CR) electrons compared
to galaxies with lower star formation activity.


title:
The SCUBA HAlf Degree Extragalactic Survey (SHADES) -- II. Submillimetre
  maps, catalogue and number counts

abstract:
  We present the maps, source catalogue and number counts of the largest, most
complete and unbiased extragalactic submillimetre survey ever undertaken: the
850-micron SCUBA HAlf Degree Extragalactic Survey (SHADES). Using the
Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell
Telescope (JCMT), SHADES mapped two separate regions of sky: the
Subaru/XMM-Newton Deep Field (SXDF) and the Lockman Hole East (LH). These SCUBA
maps cover 720 square arcmin with an RMS noise level of about 2 mJy and have
uncovered >100 submillimetre galaxies. In order to ensure the utmost robustness
of the resulting source catalogue, data reduction was independently carried out
by four sub-groups drawn within the SHADES team, providing an unprecedented
degree of reliability with respect to other SCUBA catalogues available from the
literature. Individual source lists from the four groups were combined to
produce a robust 120-object SHADES catalogue; an invaluable resource for
follow-up campaigns aiming to study the properties of a complete and consistent
sample of submillimetre galaxies. We present differential and integral source
number counts of submillimetre galaxies and find that the differential counts
are better fit with a broken power-law or a Schechter function than with a
single power-law; the SHADES data alone significantly show that a break is
required at several mJy, although the precise position of the break is not well
constrained. We also find that an 850-micron survey complete down to 2 mJy
would resolve 20-30 per cent of the Far-IR background into point sources.
[abridged]


title: Crossing the Phantom Divide

abstract:
  We consider fluid perturbations close to the "phantom divide" characterised
by p = -rho and discuss the conditions under which divergencies in the
perturbations can be avoided. We find that the behaviour of the perturbations
depends crucially on the prescription for the pressure perturbation delta-p.
The pressure perturbation is usually defined using the dark energy rest-frame,
but we show that this frame becomes unphysical at the divide. If the pressure
perturbation is kept finite in any other frame, then the phantom divide can be
crossed. Our findings are important for generalised fluid dark energy used in
data analysis (since current cosmological data sets indicate that the dark
energy is characterised by p ~ -rho so that p < -rho cannot be excluded) as
well as for any models crossing the phantom divide, like some modified gravity,
coupled dark energy and braneworld models. We also illustrate the results by an
explicit calculation for the "Quintom" case with two scalar fields.


title: The Carina-Near Moving Group

abstract:
  We identify a group of ~20 co-moving, mostly southern hemisphere, ~200 Myr
old stars near Earth. Of the stars likely to be members of this Carina-Near
Moving Group, in either its nucleus (~30 pc from Earth) or surrounding stream,
all but 3 are plausible members of a multiple star system. The nucleus is
(coincidentally) located quite close to the nucleus of the AB Doradus moving
group notwithstanding that the two groups have substantially different ages and
Galactic space motions, UVW.


title: The evolution of the number density of large disk galaxies in COSMOS

abstract:
  We study a sample of approximately 16,500 galaxies with I_AB <= 22.5 in the
COSMOS field. Structural information on the galaxies is derived by fitting
single Sersic models to their two-dimensional surface brightness distributions.
We investigate the evolution of the number density of disk galaxies larger than
5 kpc between redshift z~1 and the present epoch. To this end, we use the
measurements of the half-light radii to construct, as a function of redshift,
the size function of both the total disk galaxy population and of disk galaxies
split in four bins of bulge-to-disk ratio. Furthermore, we use a selected
sample of roughly 1800 SDSS galaxies to calibrate our results with respect to
the local universe. We find that: (i) The number density of disk galaxies with
intermediate sizes (r_{1/2}~5-7 kpc) remains nearly constant from z~1 to today.
(ii) The number density of the largest disks (r_{1/2}>7 kpc) decreases by a
factor of about two out to z~1. (iii) There is a constancy in the number
density of large bulgeless disks out to z~1; the deficit of large disks at
early epochs seems to arise from a smaller number of bulged disks. Our results
indicate that the bulk of the large disk galaxy population has completed its
growth by z~1, and support the hypothesis that secular evolution processes
produce - or at least add stellar mass to - the bulge components of disk
galaxies.


title:
A line profile analysis of the pulsating red giant star epsilon Ophiuchi
  (G9.5III)

abstract:
  So far, solar-like oscillations have been studied using radial velocity
and/or light curve variations, which reveal frequencies of the oscillation
modes. Line-profile variations, however, are also a valuable diagnostic to
characterise radial and non-radial oscillations, including frequencies,
amplitudes, the spherical mode wavenumbers (l,m) and the stellar inclination
angle. Here we present a line profile analysis of epsilon Ophiuchi, which is a
pulsating red giant. The main differences compared to previous line profile
analyses done for heat-driven oscillations are the small amplitudes and the
predicted short damping and re-excitation times in red giants.
  Two line diagnostics have been tested to see whether these are sensitive to
the small line profile variations present in red giants. In addition, line
profiles have been simulated with short damping and re-excitation times and are
compared with the observations. This comparison reveals that non-radial modes
are detected in the observed line profile variations of epsilon Ophiuchi. This
is rather surprising, as theoretical predictions favours the occurrence of
radial modes.


title:
The Zurich Extragalactic Bayesian Redshift Analyzer (ZEBRA) and its
  first application: COSMOS

abstract:
  We present ZEBRA, the Zurich Extragalactic Bayesian Redshift Analyzer. The
current version of ZEBRA combines and extends several of the classical
approaches to produce accurate photometric redshifts down to faint magnitudes.
In particular, ZEBRA uses the template-fitting approach to produce Maximum
Likelihood and Bayesian redshift estimates based on: (1.) An automatic
iterative technique to correct the original set of galaxy templates to best
represent the SEDs of real galaxies at different redshifts; (2.) A training set
of spectroscopic redshifts for a small fraction of the photometric sample; and
(3.) An iterative technique for Bayesian redshift estimates, which extracts the
full two-dimensional redshift and template probability function for each
galaxy. We demonstrate the performance of ZEBRA by applying it to a sample of
866 I_AB <= 22.5 COSMOS galaxies with available u*, B, V, g', r', i', z' and
K_s photometry and zCOSMOS spectroscopic redshifts in the range 0 < z < 1.3.
Adopting a 5-sigma-clipping that excludes less than 10 galaxies, both the
Maximum Likelihood and Bayesian estimates for this sample have an accuracy
dz/1+z better than 0.03. Similar accuracies are recovered using mock galaxies.


title:
Carbon Deficiency in Externally-Polluted White Dwarfs: Evidence for
  Accretion of Asteroids

abstract:
  Existing determinations show that n(C)/n(Fe) is more than a factor of 10
below solar in the atmospheres of three white dwarfs that appear to be
externally-polluted. These results are not easily explained if the stars have
accreted interstellar matter, and we re-interpret these measurements as
evidence that these stars have accreted asteroids of a chrondritic composition.


title:
Production of Hypervelocity Stars through Encounters with Stellar-Mass
  Black Holes in the Galactic Centre

abstract:
  Stars within 0.1 pc of the supermassive black hole Sgr A* at the Galactic
centre are expected to encounter a cluster of stellar-mass black holes (BHs)
that have segregated to that region. Some of these stars will scatter off an
orbiting BH and be kicked out of the Galactic centre with velocities up to
~2000 km/s. We calculate the resulting ejection rate of hypervelocity stars
(HVSs) by this process under a variety of assumptions, and find it to be
comparable to the tidal disruption rate of binary stars by Sgr A*, first
discussed by Hills (1988). Under some conditions, this novel process is
sufficient to account for all of the hypervelocity B-stars observed in the
halo, and may dominate the production rate of all HVSs with lifetimes much less
than the relaxation time-scale at a distance ~2 pc from Sgr A* (>~ 2 Gyr).
Since HVSs are produced by at least two unavoidable processes, the statistics
of HVSs could reveal bimodal velocity and mass distributions, and can constrain
the distribution of BHs and stars in the innermost 0.1 pc around Sgr A*.


title:
Magnetar-Driven Magnetic Tower as a Model for Gamma-Ray Bursts and
  Asymmetric Supernovae

abstract:
  We consider a newly-born millisecond magnetar, focusing on its interaction
with the dense stellar plasma in which it is initially embedded. We argue that
the confining pressure and inertia of the surrounding plasma acts to collimate
the magnetar's Poynting-flux-dominated outflow into tightly beamed jets and
increases its magnetic luminosity. We propose this process as an essential
ingredient in the magnetar model for gamma-ray burst and asymmetric supernova
central engines. We introduce the ``pulsar-in-a-cavity'' as an important model
problem representing a magnetized rotating neutron star inside a collapsing
star. We describe its essential properties and derive simple estimates for the
evolution of the magnetic field and the resulting spin-down power. We find that
the infalling stellar mantle confines the magnetosphere, enabling a gradual
build-up of the toroidal magnetic field due to continuous twisting. The growing
magnetic pressure eventually becomes dominant, resulting in a
magnetically-driven explosion. The initial phase of the explosion is
quasi-isotropic, potentially exposing a sufficient amount of material to
$^{56}$Ni-producing temperatures to result in a bright supernova. However, if
significant expansion of the star occurs prior to the explosion, then very
little $^{56}$Ni is produced and no supernova is expected. In either case, hoop
stress subsequently collimates the magnetically-dominated outflow, leading to
the formation of a magnetic tower. After the star explodes, the decrease in
bounding pressure causes the magnetic outflow to become less beamed. However,
episodes of late fallback can reform the beamed outflow, which may be
responsible for late X-ray flares.


title:
A Distributed Population of Low Mass Pre-Main Sequence Stars near the
  Taurus Molecular Clouds

abstract:
  We present a drift scan survey covering a ~5 deg by 50 deg region toward the
southern portion of the Taurus-Auriga molecular cloud. Data taken in the B,R,I
filters with the Quest-2 camera on the Palomar 48-inch telescope were combined
with 2MASS near-infrared photometry to select candidate young stars. Follow-up
optical spectroscopy of 190 candidates led to identification of 42 new low mass
pre-main sequence stars with spectral types M4-M8, of which approximately half
exhibit surface gravity signatures similar to known Taurus stars while the
other half exhibit surface gravity signatures similar to members of the
somewhat older Upper Sco, TW Hya and Beta Pic associations. The pre-main
sequence stars are spread over ~35 deg, and many are located well outside of
previously explored regions. From assessment of the spatial and proper motion
distributions, we argue that the new pre-main sequence stars identified far
from the clouds cannot have originated from the vicinity of the 1-2 Myr-old
subclusters which contain the bulk of the identified Taurus members, but
instead represent a newly-identified area of recent star-formation near the
clouds.


title:
A New Algorithm for 2-D Transport for Astrophysical Simulations: I.
  General Formulation and Tests for the 1-D Spherical Case

abstract:
  We derive new equations using the mixed-frame approach for one- and
two-dimensional (axisymmetric) time-dependent radiation transport and the
associated couplings with matter. Our formulation is multi-group and
multi-angle and includes anisotropic scattering, frequency(energy)-dependent
scattering and absorption, complete velocity dependence to order v/c, rotation,
and energy redistribution due to inelastic scattering. Hence, the "2D"
realization is actually "6 1/2"-dimensional. The effects of radiation viscosity
are automatically incorporated. Moreover, we develop
Accelerated-Lambda-Iteration, Krylov subspace (GMRES),
Discontinuous-Finite-Element, and Feautrier numerical methods for solving the
equations and present the results of one-dimensional numerical tests of the new
formalism. The virtues of the mixed-frame approach include simple velocity
dependence with no velocity derivatives, straight characteristics, simple
physical interpretation, and clear generalization to higher dimensions. Our
treatment can be used for both photon and neutrino transport, but we focus on
neutrino transport and applications to core-collapse supernova theory in the
discussions and examples.


title: Investigating the Andromeda Stream: III. A Young Shell System in M31

abstract:
  Published maps of red giant stars in the halo region of M31 exhibit a giant
stellar stream to the south of this galaxy, as well as a giant "shelf" to the
northeast of M31's center. Using these maps, we find that there is a fainter
shelf of comparable size on the western side as well. By choosing appropriate
structural and orbital parameters for an accreting dwarf satellite within the
accurate M31 potential model of Geehan et al. (2006), we produce a very similar
structure in an N-body simulation. In this scenario, the tidal stream produced
at pericenter of the satellite's orbit matches the observed southern stream,
while the forward continuation of this tidal stream makes up two orbital loops,
broadened into fan-like structures by successive pericentric passages; these
loops correspond to the NE and W shelves. The tidal debris from the satellite
also reproduces a previously-observed "stream" of counterrotating PNe and a
related stream seen in red giant stars. The debris pattern in our simulation
resembles the shell systems detected around many elliptical galaxies, though
this is the first identification of a shell system in a spiral galaxy and the
first in any galaxy close enough to allow measurements of stellar velocities
and relative distances. We discuss the physics of these partial shells,
highlighting the role played by spatial and velocity caustics in the
observations. We show that kinematic surveys of the tidal debris will provide a
sensitive measurement of M31's halo potential, while quantifying the surface
density of debris in the shelves will let us reconstruct the original mass and
time of disruption of the progenitor satellite.


title:
Calibrating the Solar Dynamo: Magnetic Activity Cycles of Southern
  Sun-like Stars

abstract:
  The solar magnetic activity cycle is responsible for periodic episodes of
severe space weather, which can perturb satellite orbits, interfere with
communications systems, and bring down power grids. Much progress has recently
been made in forecasting the strength and timing of this 11-year cycle, using a
predictive flux-transport dynamo model (Dikpati 2005, Dikpati et al. 2006). We
can strengthen the foundation of this model by extending it to match
observations of similar magnetic activity cycles in other Sun-like stars, which
exhibit variations in their Ca II H and K emission on time scales from 2.5 to
25 years (Baliunas et al. 1995). This broad range of cycle periods is thought
to reflect differences in the rotational properties and the depth of the
surface convection zone for stars with various masses and ages.
Asteroseismology is now yielding direct measurements of these quantities for
individual stars, but the most promising asteroseismic targets are in the
southern sky (alpha Cen A, alpha Cen B, beta Hyi), while the existing activity
cycle survey is confined to the north. We are initiating a long-term survey of
Ca II H and K emission for a sample of 92 southern Sun-like stars to measure
their magnetic activity cycles and rotational properties, which will ultimately
provide independent tests of solar dynamo models.


title:
Oxygen abundances in the Galactic Bulge: evidence for fast chemical
  enrichment

abstract:
  AIMS: We spectroscopically characterize the Galactic Bulge to infer its star
formation timescale, compared to the other Galactic components, through the
chemical signature on its individual stars.
  METHODS: We derived iron and oxygen abundances for 50 K giants in four fields
towards the Galactic bulge. High resolution (R=45,000) spectra for the target
stars were collected with FLAMES-UVES at the VLT.
  RESULTS: Oxygen, as measured from the forbidden line at 6300 \AA, shows a
well-defined trend with [Fe/H], with [O/Fe] higher in bulge stars than in thick
disk ones, which were known to be more oxygen enhanced than thin disk stars.
  CONCLUSIONS: These results support a scenario in which the bulge formed
before and more rapidly than the disk, and therefore the MW bulge can be
regarded as a prototypical old spheroid, with a formation history similar to
that of early-type (elliptical) galaxies.


title:
Radial and rotational velocities of young brown dwarfs and very low-mass
  stars in the Upper Scorpius OB association and the rho Ophiuchi cloud core

abstract:
  We present the results of a radial velocity (RV) survey of 14 brown dwarfs
(BDs) and very low-mass (VLM) stars in the Upper Scorpius OB association
(UScoOB) and 3 BD candidates in the rho Ophiuchi dark cloud core. We obtained
high-resolution echelle spectra at the Very Large Telescope using Ultraviolet
and Visual Echelle Spectrograph (UVES) at two different epochs for each object,
and measured the shifts in their RVs to identify candidates for binary/multiple
systems in the sample. The average time separation of the RV measurements is
21.6d, and our survey is sensitive to the binaries with separation < 0.1 au. We
found that 4 out of 17 objects (or 24^{+16}_{-13} per cent by fraction) show a
significant RV change in 4-33d time scale, and are considered as
binary/multiple `candidates.' We found no double-lined spectroscopic binaries
in our sample, based on the shape of cross-correlation curves. The RV
dispersion of the objects in UScoOB is found to be very similar to that of the
BD and VLM stars in Chamaeleon I (Cha I). We also found the distribution of the
mean rotational velocities (v sin i) of the UScoOB objects is similar to that
of the Cha I, but the dispersion of v sin i is much larger than that of the Cha
I objects.


title: H.E.S.S. Observations of LS 5039

abstract:
  Recent observations of the binary system LS5039 with the High Energy
Stereoscopic System (H.E.S.S.) revealed that its Very High Energy (VHE)
gamma-ray emission is modulated at the 3.9 days orbital period of the system.
The bulk of the emission is largely confined to half of the orbit, peaking
around the inferior conjunction epoch of the compact object. The flux
modulation provides the first indication of gamma-ray absorption by pair
production on the intense stellar photon field. This implies that the
production region size must be not significantly greater than the gamma-gamma
photosphere size (~1 AU), thus excluding the large scale collimated outflows or
jets (extending out to ~1000 AU). A hardening of the spectrum is also observed
at the same epoch between 0.2 and a few TeV which is unexpected under a pure
absorption scenario and could rather arise from variation with phase in the
maximum electron energy and/or the dominant VHE gamma-ray production mechanism.
This first-time observation of modulated gamma-ray emission allows precise
tests of the acceleration and emission models in binary systems.


title: Unstable modes of non-axisymmetric gaseous discs

abstract:
  We present a perturbation theory for studying the instabilities of
non-axisymmetric gaseous discs. We perturb the dynamical equations of
self-gravitating fluids in the vicinity of a non-axisymmetric equilibrium, and
expand the perturbed physical quantities in terms of a complete basis set and a
small non-axisymmetry parameter $\epsilon$. We then derive a linear eigenvalue
problem in matrix form, and determine the pattern speed, growth rate and mode
shapes of the first three unstable modes. In non-axisymmetric discs the
amplitude and phase angle of travelling waves are functions of both the radius
$R$ and the azimuthal angle $\phi$. This is due to the interaction of different
wave components in the response spectrum. We demonstrate that wave interaction
in unstable discs with small initial asymmetries, can develop dense clumps
during the phase of exponential growth. Local clumps, which occur on the major
spiral arms, can constitute seeds of gas giant planets in accretion discs.


title: 2D Fokker-Planck models of rotating clusters

abstract:
  Globular clusters rotate significantly, and with the increasing amount of
detailed morphologicaland kinematical data obtained in recent years on galactic
globular clusters many interesting features show up. We show how our
theoretical evolutionary models of rotating clusters can be used to obtain
fits, which at least properly model the overall rotation and its implied
kinematics in full 2D detail (dispersions, rotation velocities). Our simplified
equal mass axisymmetric rotatingmodel provides detailed two-dimensional
kinematical and morphological data for star clusters. The degree of rotation is
not dominant in energy, but also non-negligible for the phase space
distribution function, shape and kinematics of clusters. Therefore the models
are well applicable for galactic globular clusters. Since previously published
papers on that matter by us made it difficult to do detailed comparisons with
observations we provide a much more comprehensive and easy-to-use set of data
here, which uses as entries dynamical age and flattening of observed cluster
andthen offers a limited range of applicable models in full detail. The method,
data structure and some exemplary comparison with observations are presented.
Future work will improve modelling anddata base to take a central black hole, a
mass spectrum and stellar evolution into account.


title: The detection of the (J,K)=(18,18) line of NH3

abstract:
  The first astronomical detection of the metastable ($J,K$) = (18,18) line of
NH3 is reported. With 3130 K above the ground state, this is the NH3 line with
by far the highest energy detected in interstellar space. It is observed in
absorption toward the galactic center star forming region Sgr B2. There is a
clear detection toward Sgr B2(M) and a likely one toward SgrB2(N). An upper
limit for emission is determined for Orion-KL. If we combine the (18,18) line
results from Sgr B2(M) with the previously measured (12,12) absorption line, we
find a rotation temperature of >1300 K for the absorbing cloud. This is at
least a factor of two higher than previously derived values from less highly
excited ammonia lines, giving a lower limit to the kinetic temperature. There
is a hot low density gas component in the envelope of SgrB2. It is possible
that the (18,18) line arises in this region. The radial velocity of the low
density, hot envelope is the same as that of the dense hot cores, so the
(18,18) line could also arise in the dense hot cores where non-metastable (J>K)
absorption lines from energy levels of up to 1350 K above the ground state have
been observed. A discussion of scenarios is presented.


title: The optical and near-infrared properties of nearby groups of galaxies

abstract:
  We present a study of the optical (BRI) and near-infrared (JHK) luminosity
fuctions (LFs) of the GEMS sample of 60 nearby groups of galaxies between
0<z<0.04, with our optical CCD photometry and near-IR photometry from the 2MASS
survey. The LFs in all filters show a depletion of galaxies of intermediate
luminosity, two magnitudes fainter than L*, within 0.3 R{500} from the centres
of X-ray faint groups. This feature is not as pronounced in X-ray bright
gropus, and vanishes when LFs are found out to R{500}, even in the X-ray dim
groups. We argue that this feature arises due to the enhanced merging of
intermediate-mass galaxies in the dynamically sluggish environment of low
velocity-dispersion groups, indicating that merging is important in galaxy
evolution even at z~0.


title: Five new very low mass binaries

abstract:
  We report the discovery of companions to 5 nearby late M dwarfs (>M5),
LHS1901, LHS4009, LHS6167, LP869-26 and WT460, and we confirm that the recently
discovered mid-T brown dwarf companion to SCR1845-6357 is physically bound to
that star. These discoveries result from our adaptive optics survey of all M
dwarfs within 12 pc. The new companions have spectral types M5 to L1, and
orbital separations between 1 and 10 AU. They add significantly to the number
of late M dwarfs binaries in the immediate solar neighbourhood, and will
improve the multiplicity statistics of late M dwarfs. The expected periods
range from 3 to 130 years. Several pairs thus have good potential for accurate
mass determination in this poorly sampled mass range.


title: First results from the Pierre Auger Observatory

abstract:
  We review in these notes the status of the construction of the Pierre Auger
Observatory and present the first Physics results, based on the data collected
during the first year and a half of operation. These results are preliminary,
once the work to understand the systematics of the detectors are still
underway. We discuss the cosmic ray spectrum above 3 EeV, based on the
measurement done using the Surface Detector and the Fluorescence Detector,
both, components of the observatory. We discuss, as well, the search for
anisotropy near the Galactic Center and the limit on the photon fraction at the
highest energies.


title: The evolution of binary star clusters and the nature of NGC2136/NGC2137

abstract:
  We study the evolution of bound pairs of star clusters by means of direct
N-body simulations. Our simulations include mass loss by stellar evolution. The
initial conditions are selected to mimic the observed binary star cluster NGC
2136 and NGC 2137 in the Large Magellanic Cloud. Based on the rather old ages
($\sim 100$ Myr), masses, sizes of the two clusters and their projected
separation, we conclude that the cluster pair must have been born with an
initial separation of 15--20 pc. Clusters with a smaller initial separation
tend to merge in $\aplt 60$ Myr due to loss of angular momentum from escaping
stars. Clusters with a larger initial separation tend to become even more
widely separated due to mass loss from the evolving stellar populations. The
early orbital evolution of a binary cluster is governed by mass loss from the
evolving stellar population and by loss of angular momentum from escaping
stars. Mass loss by stellar winds and supernovae explosions in the first $\sim
30$ Myr causes the binary to expand and the orbit to become eccentric. The
initially less massive cluster expands more quickly than the binary separation
increases, and is therefore bound to initiate mass transfer to the more massive
cluster. This process is quite contrary to stellar binaries in which the more
massive star tends to initiate mass transfer. Since mass transfer proceeds on a
thermal timescale from the less massive to the more massive cluster, this
semi-detached phase is quite stable, even in an eccentric orbit until the
orbital separation reaches the gyration radius of the two clusters, at which
point both clusters merge to one.


title: Observational Constraints on Cluster Evolution

abstract:
  Current observational constraints on the dynamical evolution of star clusters
are reviewed. Theory and observations now agree nicely on the mass dependency
and time scales for disruption of young star clusters in galactic disks, but
many problems still await resolution. The origin of the mass function of old
globular clusters, and its (near) invariance with respect to host galaxy
properties and location within the host galaxy remain prominent puzzles. Most
current models fail to reproduce the globular cluster mass function as a result
of dynamical evolution from an initial power-law, except under very specific
conditions which are not generally consistent with observations. How well do we
actually know the proper initial conditions? The cluster initial mass function
(CIMF) seems to be consistent with a power-law with exponent alpha~ -2 in most
present-day star forming galaxies, but the limits of the mass range over which
this approximation is valid remain poorly constrained both observationally and
theoretically. Furthermore, there are hints that some dwarf galaxies may have
CIMFs which deviate from a power-law.


title: The Lidar System of the Pierre Auger Observatory

abstract:
  The Pierre Auger Observatory in Malargue, Argentina, is designed to study the
origin of ultrahigh energy cosmic rays with energies above 10^18 eV. The energy
calibration of the detector is based on a system of four air fluorescence
detectors. To obtain reliable calorimetric information from the fluorescence
stations, the atmospheric conditions at the experiment's site need to be
monitored continuously during operation. One of the components of the
observatory's atmospheric monitoring system is a set of four elastic
backscatter lidar stations, one station at each of the fluorescence detector
sites. This paper describes the design, current status, standard operation
procedure, and performance of the lidar system of the Pierre Auger Observatory.


title: A New Nearby Candidate Star Cluster in Ophiuchus at d = 170 pc

abstract:
  The recent discoveries of nearby star clusters and associations within a few
hundred pc of the Sun, as well as the order of magnitude difference in the
formation rates of the embedded and open cluster populations, suggests that
additional poor stellar groups are likely to be found at surprisingly close
distances to the Sun. Here I describe a new nearby stellar aggregate found by
virtue of the parallel proper motions, similar trigonometric parallaxes, and
consistent color-magnitude distribution of its early-type members. The 120
Myr-old group lies in Ophiuchus at $d$ $\simeq$ 170 pc, with its most massive
member being the 4th-magnitude post-MS B8II-III star $\mu$ Oph. The group may
have escaped previous notice due to its non-negligible extinction ($A_V$
$\simeq$ 0.9 mag). If the group was born with a normal initial mass function,
and the nine B- and A-type systems represent a complete system of
intermediate-mass stars, then the original population was probably of order
$\sim$200 systems. The age and space motion of the new cluster are very similar
to those of the Pleiades, $\alpha$ Per cluster, and AB Dor Moving Group,
suggesting that these aggregates may have formed in the same star-forming
complex some $\sim10^8$ yr ago.


title:
Suzaku observation of the metallicity distribution in the intracluster
  medium of the Fornax cluster

abstract:
  The metallicity distribution in the Fornax cluster was studied with the XIS
instrument onboard the Suzaku satellite. K-shell lines of O and Mg were
resolved clearly, and the abundances of O, Mg, Si, S and Fe were measured with
good accuracy. The region within a 4' radius of NGC 1399 shows approximately
solar abundances of Fe, Si and S, while the O/Fe and Mg/Fe abundance ratios are
about 0.4--0.5 and 0.7 in solar units. In the outer region spanning radii
between 6' and 23', the Fe and Si abundances drop to 0.4--0.5 solar and show no
significant gradient within this region. The abundance ratios, O/Fe and Mg/Fe,
are consistent with those in the central region. We also measured the Fe
abundance around NGC 1404 to be approximately solar, and the O, Ne and Mg
abundances to be 0.5--0.7 times the Fe level. The significant relative
enhancement of Fe within 130 kpc of NGC 1399 and in NGC 1404 indicates an
origin in SN Ia, in contrast to the species O, Ne, and Mg which reflect the
stellar metallicity. The mass-to-light ratios for O and Fe within 130 kpc of
NGC 1399 are over an order of magnitude lower than those in rich clusters,
reflecting the metal enrichment history of this poor cluster.


title:
The Magnificent Seven: Magnetic fields and surface temperature
  distributions

abstract:
  Presently seven nearby radio-quiet isolated neutron stars discovered in ROSAT
data and characterized by thermal X-ray spectra are known. They exhibit very
similar properties and despite intensive searches their number remained
constant since 2001 which led to their name ``The Magnificent Seven''. Five of
the stars exhibit pulsations in their X-ray flux with periods in the range of
3.4 s to 11.4 s. XMM-Newton observations revealed broad absorption lines in the
X-ray spectra which are interpreted as cyclotron resonance absorption lines by
protons or heavy ions and / or atomic transitions shifted to X-ray energies by
strong magnetic fields of the order of 10^13 G. New XMM-Newton observations
indicate more complex X-ray spectra with multiple absorption lines. Pulse-phase
spectroscopy of the best studied pulsars RX J0720.4-3125 and RBS 1223 reveals
variations in derived emission temperature and absorption line depth with pulse
phase. Moreover, RX J0720.4-3125 shows long-term spectral changes which are
interpreted as due to free precession of the neutron star. Modeling of the
pulse profiles of RX J0720.4-3125 and RBS 1223 provides information about the
surface temperature distribution of the neutron stars indicating hot polar caps
which have different temperatures, different sizes and are probably not located
in antipodal positions.