title: AEGIS20: a radio survey of the Extended Groth Strip

abstract:
  We describe AEGIS20 - a radio survey of the Extended Groth Strip (EGS)
conducted with the Very Large Array (VLA) at 1.4GHz. The resulting catalog
contains 1,123 emitters and is sensitive to ultraluminous starbursts to z<=1.3,
well matched to the redshift range of the DEEP2 spectroscopic survey in this
region. We use stacking techniques to explore the uJy-level emission from a
variety of galaxy populations selected via conventional criteria - Lyman-break
galaxies (LBGs), distant red galaxies (DRGs), UV-selected galaxies and
extremely red objects (EROs) - determining their properties as a function of
color, magnitude and redshift and their extinction-free contributions to the
history of star formation. We confirm the familiar pattern that the
star-formation-rate (SFR) density, SFRD, rises by at least ~5x from z=0-1,
although we note highly discrepant UV- and radio-based SFR estimates. Our
radio-based SFRs become more difficult to interpret at z>1 where correcting for
contamination by radio-loud active galactic nuclei (AGN) comes at the price of
rejecting luminous starbursts. Whilst stacking radio images is a useful
technique, accurate radio-based SFRs for z>>1 galaxies require precise
redshifts and extraordinarily high-fidelity radio data to identify and remove
accretion-related emission.


title:
AEGIS: Enhancement of Dust-enshrouded Star Formation in Close Galaxy
  Pairs and Merging Galaxies up to z ~ 1

abstract:
  Using data from the DEEP2 Galaxy Redshift Survey and HST/ACS imaging in the
Extended Groth Strip, we select nearly 100 interacting galaxy systems including
kinematic close pairs and morphologically identified merging galaxies. Spitzer
MIPS 24 micron fluxes of these systems reflect the current dusty star formation
activity, and at a fixed stellar mass (M_{*}) the median infrared luminosity
(L_{IR}) among merging galaxies and close pairs of blue galaxies is twice (1.9
+/- 0.4) that of control pairs drawn from isolated blue galaxies. Enhancement
declines with galaxy separation, being strongest in close pairs and mergers and
weaker in wide pairs compared to the control sample. At z ~ 0.9, 7.1% +/- 4.3%
of massive interacting galaxies (M_{*} > 2*10^{10} M_{solar}) are found to be
ULIRGs, compared to 2.6% +/- 0.7% in the control sample. The large spread of IR
luminosity to stellar mass ratio among interacting galaxies suggests that this
enhancement may depend on the merger stage as well as other as yet unidentified
factors (e.g., galaxy structure, mass ratio, orbital characteristics, presence
of AGN or bar). The contribution of interacting systems to the total IR
luminosity density is moderate (<= 36 %).


title:
The evolution of the bi-modal colour distribution of galaxies in SDSS
  groups

abstract:
  We analyse $u-r$ colour distributions for several samples of galaxies in
groups drawn from the Fourth Data Release of the Sloan Digital Sky Survey. For
all luminosity ranges and environments considered the colour distributions are
well described by the sum of two Gaussian functions. We find that the fraction
of galaxies in the red sequence is an increasing function of group virial mass.
We also study the evolution of the galaxy colour distributions at low redshift,
$z\le0.18$ in the field and in groups for galaxies brighter than
$M_r-5\log(h)=-20$, finding significant evidence of recent evolution in the
population of galaxies in groups. The fraction of red galaxies monotonically
increases with decreasing redshift, this effect implies a much stronger
evolution of galaxies in groups than in the field.


title:
All-wavelength Extended Groth strip International Survey: the
  environment of X-ray sources at z~1

abstract:
  We explore the environment of z~1 AGN using a sample of 53 spectroscopically
identified X-ray sources in the All-wavelength Extended Groth strip
International Survey. We quantify the local density in the vicinity of an X-ray
source by measuring the projected surface density of spectroscopically
identified optical galaxies within a radius defined by the 3rd nearest
neighbour. Our main result is that X-ray selected AGN at z~1 avoid underdense
regions at the 99.89% confidence level. Moreover, although we find that the
overall population shares the same (rich) environment with optical galaxies of
similar U-B and M_B, there is also tentative evidence (96%) that AGN with blue
colors (U-B<1) reside in denser environments compared to optical galaxies. We
argue that the results above are a consequence of the whereabouts of massive
galaxies, capable of hosting supermassive black holes at their centers, with
available cold gas reservoirs, the fuel for AGN activity. At z~1 an increasing
fraction of such systems are found in dense regions.


title: The WMAP normalization of inflationary cosmologies

abstract:
  We use the three-year WMAP observations to determine the normalization of the
matter power spectrum in inflationary cosmologies. In this context, the
quantity of interest is not the normalization marginalized over all parameters,
but rather the normalization as a function of the inflationary parameters n and
r with marginalization over the remaining cosmological parameters. We compute
this normalization and provide an accurate fitting function. The statistical
uncertainty in the normalization is 3 percent, roughly half that achieved by
COBE. We use the k-l relation for the standard cosmological model to identify
the pivot scale for the WMAP normalization. We also quote the inflationary
energy scale corresponding to the WMAP normalization.


title:
Discovery of an X-ray Jet and Extended Jet Structure in the Quasar PKS
  1055+201

abstract:
  This letter reports rich X-ray jet structures found in the Chandra
observation of PKS 1055+201. In addition to an X-ray jet coincident with the
radio jet we detect a region of extended X-ray emission surrounding the jet as
far from the core as the radio hotspot to the North, and a similar extended
X-ray region along the presumed path of the unseen counterjet to the Southern
radio lobe. Both X-ray regions show a similar curvature to the west, relative
to the quasar. We interpret this as the first example where we separately
detect the X-ray emission from a narrow jet and extended, residual jet plasma
over the entire length of a powerful FRII jet.


title:
Density-Functional-Theory Calculations of Matter in Strong Magnetic
  Fields: II. Infinite Chains and Condensed Matter

abstract:
  We present new, ab initio calculations of the electronic structure of
one-dimensional infinite chains and three-dimensional condensed matter in
strong magnetic fields ranging from B=10^12 G to 2x10^15 G, appropriate for
observed magnetic neutron stars. At these field strengths, the magnetic forces
on the electrons dominate over the Coulomb forces, and to a good approximation
the electrons are confined to the ground Landau level. Our calculations are
based on the density functional theory, and use a local magnetic
exchange-correlation function appropriate in the strong field regime. The band
structures of electrons in different Landau orbitals are computed
self-consistently. Numerical results of the ground-state energies and electron
work functions are given for one-dimensional chains of H, He, C, and Fe.
Fitting formulae for the B-dependence of the energies are also provided. For
all the field strengths considered in this paper, hydrogen, helium, and carbon
chains are found to be bound relative to individual atoms (although for B less
than a few x 10^12 G, the relative binding between C and C_infinity is small).
Iron chains are significantly bound for B>10^14 G and are weakly bound if at
all at B<10^13 G. We also study the cohesive property of three-dimensional
condensed matter of H, He, C, and Fe at zero pressure, constructed from
interacting chains in a body-centered tetragonal lattice. Such
three-dimensional condensed matter is found to be bound relative to individual
atoms, with the cohesive energy increasing rapidly with increasing B.


title: Discovery of a z=6.1 Radio-Loud Quasar in the NDWFS

abstract:
  From examination of only 4 deg^2 of sky in the NOAO Deep Wide-Field Survey
(NDWFS) region, we have identified the first radio-loud quasar at a redshift
z>6. The object, FIRST J1427385+331241, was discovered by matching the FLAMEX
IR survey to FIRST survey radio sources with NDWFS counterparts. One candidate
z>6 quasar was found, and spectroscopy with the Keck II telescope confirmed its
identification, yielding a redshift z=6.12. The object is a Broad Absorption
Line (BAL) quasar with an optical luminosity of M_B ~ -26.9 and a
radio-to-optical flux ratio ~ 60. Two MgII absorptions systems are present at
redshifts of z=2.18 and z=2.20. We briefly discuss the implications of this
discovery for the high-redshift quasar population.


title: Testing General Relativity with High-Resolution Imaging of Sgr A*

abstract:
  Submilliarcsecond astrometry and imaging of the black hole Sgr A* at the
Galactic Center may become possible in the near future at infrared and
submillimetre wavelengths. This resolution is sufficient to observe the
silhouette the supermassive black hole in the Galactic center casts upon
background emission. However, more exciting is the prospect of observing ``hot
spots'' in the accretion flow. Here we discuss how such measurements may be
used to test not only the consistency of General Relativity, but also the
validity of the Kerr metric in particular.


title:
Ultracompact Blue Dwarf Galaxies: Hubble Space Telescope Imaging and
  Stellar Population Analysis

abstract:
  We present deep Hubble Space Telescope Advanced Camera for Surveys / High
Resolution Channel U, narrow-V, and I images of nine "ultracompact" blue dwarf
galaxies (UCBDs) selected from the Sloan Digital Sky Survey. We define UCBDs as
local (z < 0.01) star-forming galaxies having angular diameters < 6" and
physical sizes < 1 kpc. They are also among the most metal-poor galaxies known,
and are found to reside within voids. Both the HST images and the objects'
optical spectra reveal that they are composites of young (~1 Myr) populations
that dominate their light, and older (~10 Gyr) populations that dominate their
stellar masses, which we estimate to be ~10^7 - 10^8 Msol. An intermediate-age
population is also indicated in most cases. The objects are not as dynamically
disturbed as the prototype UCBD, POX 186, but the structure of several of them
suggests that their current starbursts have been triggered by the
collisions/mergers of smaller clumps of stars. In one case, HS 0822+3542, the
ACS/HRC images resolve the object into two small (~100 pc) components which
appear to have recently collided, supporting this interpretation. In six of the
objects much of their star formation is concentrated in Young Massive Star
clusters. The evidence that the galaxies consist mainly of ~10 Gyr old stars
establishes that they are not protogalaxies; their low metallicities are more
likely to be the result of the escape of supernova ejecta, as opposed to youth.
These results are consistent with recent galaxy formation simulations which
predict that cosmic re-ionization at z ~ 6 significantly limited the subsequent
star formation of dwarf galaxies in voids due to the photo-evaporation of
baryons from their cold dark matter halos (Abridged).


title:
A Numerical Algorithm for Modeling Multigroup Neutrino-Radiation
  Hydrodynamics in Two Spatial Dimensions

abstract:
  It is now generally agreed that multidimensional, multigroup, radiation
hydrodynamics is an indispensable element of any realistic model of
stellar-core collapse, core-collapse supernovae, and protoneutron star
instabilities. We have developed a new, two-dimensional, multigroup algorithm
that can model neutrino-radiation-hydrodynamic flows in core-collapse
supernovae. Our algorithm uses an approach that is similar to the ZEUS family
of algorithms, originally developed by Stone and Norman. However, we extend
that previous work in three significant ways: First, we incorporate
multispecies, multigroup, radiation hydrodynamics in a flux-limited-diffusion
approximation. Our approach is capable of modeling pair-coupled
neutrino-radiation hydrodynamics, and includes effects of Pauli blocking in the
collision integrals. Blocking gives rise to nonlinearities in the discretized
radiation-transport equations, which we evolve implicitly in time. We employ
parallelized Newton-Krylov methods to obtain a solution of these nonlinear,
implicit equations. Our second major extension to the ZEUS algorithm is
inclusion of an electron conservation equation, which describes evolution of
electron-number density in the hydrodynamic flow. This permits following the
effects of deleptonization in a stellar core. In our third extension, we have
modified the hydrodynamics algorithm to accommodate realistic, complex
equations of state, including those having non-convex behavior. In this paper,
>... <abstract continues>


title: Local hydrodynamics and operator stability of Keplerian accretion disks

abstract:
  We discuss non-self-gravitating hydrodynamic disks in the thin disk limit.
These systems are stable according to the Rayleigh criterion, and yet there is
some evidence that the dissipative and transport processes in these disks are
hydrodynamic in nature at least some of the time. We draw on recent work on the
hydrodynamics of laboratory shear flows. Such flows are often experimentally
unstable even in the absence of a linear instability. The transition to
turbulence in these systems, as well as the large linear transient
amplification of initial disturbances, may depend upon the non-self-adjoint
nature of the differential operator that describes the dynamics of
perturbations to the background state. We find that small initial perturbations
can produce large growth in accretion disks in the shearing sheet approximation
with shearing box boundary conditions, despite the absence of any linear
instability. Furthermore, the differential operator that propagates initial
conditions forward in time is asymptotically close (as a function of Reynolds
number) to possessing growing eigenmodes. The similarity to the dynamics of
laboratory shear flows is suggestive that accretion disks might be
hydrodynamically unstable despite the lack of any known instability mechanism.


title: New age estimates of M31 globular clusters from multi-colour photometry

abstract:
  The large majority of extragalactic star cluster studies performed to date
essentially use multi-colour photometry, combined with theoretical stellar
synthesis models, to derive ages, masses, extinction estimates, and
metallicities. M31 offers a unique laboratory for studies of globular cluster
(GC) systems. In this paper, we obtain new age estimates for 91 M31 globular
clusters, based on improved photometric data, updated theoretical stellar
synthesis models and sophisticated new fitting methods. In particular, we used
photometric measurements from the Two Micron All Sky Survey (2MASS), which, in
combination with optical photometry, can partially break the well-known
age-metallicity degeneracy operating at ages in excess of a few Gyr. We show
robustly that previous age determinations based on photometric data were
affected significantly by this age-metallicity degeneracy. Except for one
cluster, the ages of our other sample GCs are all older than 1 Gyr. Their age
distribution shows populations of young and intermediate-age GCs, peaking at
$\sim3$ and 8 Gyr respectively, as well as the "usual" complement of well-known
old GCs, i.e., GCs of similar age as the majority of the Galactic GCs. Our
results also show that although there is significant scatter in metallicity at
any age, there is a noticeable lack of young metal-poor and old metal-rich GCs,
which might be indicative of an underlying age-metallicity relationship among
the M31 GC population.


title:
Primordial Non-Gaussianity and Analytical Formula for Minkowski
  Functionals of the Cosmic Microwave Background and Large-scale Structure

abstract:
  We derive analytical formulae for the Minkowski Functions of the cosmic
microwave background (CMB) and large-scale structure (LSS) from primordial
non-Gaussianity. These formulae enable us to estimate a non-linear coupling
parameter, f_NL, directly from the CMB and LSS data without relying on
numerical simulations of non-Gaussian primordial fluctuations. One can use
these formulae to estimate statistical errors on f_NL from Gaussian
realizations, which are much faster to generate than non-Gaussian ones, fully
taking into account the cosmic/sampling variance, beam smearing, survey mask,
etc. We show that the CMB data from the Wilkinson Microwave Anisotropy Probe
should be sensitive to |f_NL|\simeq 40 at the 68% confidence level. The Planck
data should be sensitive to |f_NL|\simeq 20. As for the LSS data, the late-time
non-Gaussianity arising from gravitational instability and galaxy biasing makes
it more challenging to detect primordial non-Gaussianity at low redshifts. The
late-time effects obscure the primordial signals at small spatial scales.
High-redshift galaxy surveys at z>2 covering \sim 10Gpc^3 volume would be
required for the LSS data to detect |f_NL|\simeq 100. Minkowski Functionals are
nicely complementary to the bispectrum because the Minkowski Functionals are
defined in real space and the bispectrum is defined in Fourier space. This
property makes the Minksowski Functionals a useful tool in the presence of
real-world issues such as anisotropic noise, foreground and survey masks. Our
formalism can be extended to scale-dependent f_NL easily.


title: Two-dimensional MHD simulations of relativistic magnetic reconnection

abstract:
  It has been recognized that magnetic reconnection process is of great
importance in high-energy astrophysics. We develop a new two-dimensional
relativistic resistive magnetohydrodynamic (R$^2$MHD) code, and carry out
numerical simulations of magnetic reconnection. We find that outflow velocity
reaches Alfv\'{e}n velocity in the inflow region, and that higher Alfv\'{e}n
velocity provides higher reconnection rate. We also find Lorentz contraction
plays an important role in enhancement of reconnection rate.


title: Potential Neutrino Signals from Galactic Gamma-Ray Sources

abstract:
  The recent progress made in Galactic gamma-ray astronomy using the High
Energy Stereoskopic System (H.E.S.S.) instrument provides for the first time a
population of Galactic TeV gamma-rays, and hence potential neutrino sources,
for which the neutrino flux can be estimated. Using the energy spectra and
source morphologies measured by H.E.S.S., together with new parameterisations
of pion production and decay in hadronic interactions, we estimate the signal
and background rates expected for these sources in a first-generation water
Cherenkov detector (ANTARES) and a next-generation neutrino telescope in the
Mediterranean Sea, KM3NeT, with an instrumented volume of 1 km^3. We find that
the brightest gamma-ray sources produce neutrino rates above 1 TeV, comparable
to the background from atmospheric neutrinos. The expected event rates of the
brightest sources in the ANTARES detector make a detection unlikely. However,
for a 1 km^3 KM3NeT detector, event rates of a few neutrinos per year from
these sources are expected, and the detection of individual sources seems
possible. Although generally these estimates should be taken as flux upper
limits, we discuss the conditions and type of gamma-ray sources for which the
neutrino flux predictions can be considered robust.


title: The puzzling abundance pattern of HD134439 and HD134440

abstract:
  Abundances of 18 elements are determined for the common proper-motion pair,
HD134439 and HD134440, which shows high [Mn/Fe] and low [\alpha/Fe] ratios as
compared to normal halo stars. Moreover, puzzling abundances are indicated from
elements whose origins are normally considered to be from the same
nucleosynthesis history. Particularly, we have found that [Mg/Fe] and [Si/Fe]
are lower than [Ca/Fe] and [Ti/Fe] by 0.1-0.3 dex. When elemental abundances
are interpreted in term of their condensation temperatures (Tc), obvious trends
of [X/Fe] vs. Tc for alpha elements and probably iron-peak elements as well are
shown. The hypothesis that these stars have formed from a dusty environment in
dSph galaxy provides a solution to the puzzling abundance pattern.


title: A New Measure for Weak Lensing Flexion

abstract:
  We study a possibility to use the octopole moment of gravitationally lensed
images as a direct measure of the third-order weak gravitational lensing
effect, or the gravitational flexion. It turns out that there is a natural
relation between flexion and certain combinations of octopole/higher-multipole
moments which we call the Higher Order Lensing Image's Characteristics
(HOLICs). This will allow one to measure directly flexion from observable
octopole and higher-multipole moments of background images. We show based on
simulated observations how the use of HOLICs can improve the accuracy and
resolution of a reconstructed mass map, in which we assume Gaussian
uncertainties in the shape measurements estimated using deep i'-band data of
blank fields observed with Suprime-Cam on the Subaru telescope.


title:
Ionization of large-scale absorbing haloes and feedback events from
  high-redshift radio galaxies

abstract:
  We present photoionization calculations for the spatially-extended absorbers
observed towards the extended emission line spectrum of two high-redshift radio
galaxies: 0943-242 (z=2.922) and 0200+015 (z=2.230), with the aim of
reproducing the absorber column ratio, N(CIV)/N(HI). We explore the effects of
using different UV continua in the photoionization calculations. A comparison
is drawn between the absorber in 0200+015 and the two absorbers in the lensed
Lynx Arc Nebula at z=3.36, which present similar N(CIV)/N(HI) ratios. We find
that hot stars from a powerful starburst, or a metagalactic background
radiation (MBR) in which stars dominate over quasars, are equally successful in
producing the observed N(CIV)/N(HI), assuming subsolar absorber metallicities.
These softer SEDs eliminate the factor 1000 difference in metallicity between
the two absorbers encountered in earlier work assuming a powerlaw SED. The
detected level of continuum flux in 0943-242 is consistent with stellar
ionization. If the MBR is responsible for the ionization of the radio galaxy
absorbing shells, their radii (if spherical) would be large (> 100 kpc) and
their mass would be huge (>1E12 M_Sun), implying that a feedback event within
the radiogalaxy has expelled more baryonic material than left within it. If, as
we believe more likely, stellar sources within the radiogalaxy are responsible
for the absorber's ionization, smaller radii of ~25 kpc and much smaller masses
(~1E8-1E10 M_Sun) are inferred. This radius is consistent with the observed
transition in radio source size between smaller sources where strong HI
absorption is almost ubiquitous, and the larger sources where it is mostly
lacking. Finally, we outline additional absorption line diagnostics which could
further constrain the properties of the haloes and their ionization sources.


title: Stellar winds from massive stars - What are the REAL mass-loss rates?

abstract:
  We discuss recent evidence that currently accepted mass-loss rates may need
to be revised downwards, as a consequence of previously neglected ``clumping''
of the wind. New results on the radial stratification of the corresponding
clumping factors are summarized. We investigate the influence of clumping on
the ionization equilibrium of phosphorus, which is of major relevance when
deriving constraints on the clumping factors from an analysis of the FUV PV
resonance lines.


title: VSI: a milli-arcsec spectro-imager for the VLTI

abstract:
  VLTi Spectro-Imager (VSI) is a proposition for a second generation VLTI
instrument which is aimed at providing the ESO community with the capability of
performing image synthesis at milli-arcsecond angular resolution. VSI provides
the VLTI with an instrument able to combine 4 telescopes in a baseline version
and optionally up to 6 telescopes in the near-infrared spectral domain with
moderate to high spectral resolution. The instrument contains its own fringe
tracker in order to relax the constraints onto the VLTI infrastructure. VSI
will do imaging at the milli-arcsecond scale with spectral resolution of: a)
the close environments of young stars probing the initial conditions for planet
formation; b) the surfaces of stars; c) the environment of evolved stars,
stellar remnants and stellar winds, and d) the central region of active
galactic nuclei and supermassive black holes. The science cases allowed us to
specify the astrophysical requirements of the instrument and to define the
necessary studies of the science group for phase A.


title: Radiative diffusion in stellar atmospheres: diffusion velocities

abstract:
  The present paper addresses some of the problems in the buildup of element
stratification in stellar magnetic atmospheres due to microscopic diffusion, in
particular the redistribution of momentum among the various ionisation stages
of a given element and the calculation of diffusion velocities in the presence
of inclined magnetic fields.
  We have considerably modified and extended our CARAT code to provide
radiative accelerations, not only from bound-bound but also from bound-free
transitions. In addition, our code now computes ionisation and recombination
rates, both radiative and collisional. These rates are used in calculating the
redistribution of momentum among the various ionisation stages of the chemical
elements. A careful comparison shows that the two different theoretical
approaches to redistribution that are presently available lead to widely
discrepant results for some chemical elements, especially in the magnetic case.
In the absence of a fully satisfactory theory of redistribution, we propose to
use the geometrical mean of the radiative accelerations from both methods.
  Diffusion velocities have been calculated for 28 chemical elements in a T_eff
= 12000K, log g = 4.00 stellar magnetic atmosphere with solar abundances.
Velocities and resulting element fluxes in magnetic fields are discussed; rates
of abundance changes are analysed for systematic trends with field strength and
field direction. Special consideration is given to the Si case and our results
are confronted in detail with well-known results derived more than two decades
ago.


title: TIRAVEL - Template Independent RAdial VELocity measurement

abstract:
  We propose a new approach to measure differential radial velocities, mainly
for single-lined spectroscopic binaries. The proposed procedure - TIRAVEL
(Template Independent RAdial VELocities) - does not rely on a prior theoretical
or observed template, but instead looks for a set of relative Doppler shifts
that simultaneously optimizes the alignment of all the observed spectra. We
suggest a simple measure to quantify this overall alignment and use its maximum
to measure the relative radial velocities. As a demonstration, we apply TIRAVEL
to the observed spectra of three known spectroscopic binaries, and show that in
two cases TIRAVEL performs as good as the commonly used approach, while in one
case TIRAVEL yielded a better orbital solution.


title: PVLAS Experiment: Some Astrophysical Consequences

abstract:
  The birefringent effects of photon-pseudoscalar boson (Goldstone) particle
mixing in intergalactic magnetic field are calculated for cosmological objects.
We use the recent results of PVLAS collaboration that reported recently the
observation of a rotation of the polarization plane of light propagating
through a transverse static magnetic field. Such results which were
interpretated as arising due to conversion of photon into pseudoscalar with
coupling strength $g_{a\gamma}\sim 4\times 10^{-6} GeV^{-1}$ allows us to
estimate the intergalactic magnetic field magnitude as $\sim 10^{-16} G$ based
on Hatsemekers et al. observations of extreme-scale alignments of quasar
polarization vectors. We have analyzed some additional results of astronomical
observations that could be explained by axion interpretation of the PVLAS data:
a sharp steepening of the QSO continuum short ward of $\simeq 1100$\AA,
observed circular polarization of AGNs and QSOs, discrepancy between observed
intrinsic polarization of stars in the Local Bubble and stellar spectral
classification. The observed polarization of stars in the Local Bubble can't be
explained by interstellar origin.


title:
A Comparative Study on Lithium Abundances in Solar--Type Stars With and
  Without Planets

abstract:
  We have investigated the abundance anomalies of lithium for stars with
planets in the temperature range of 5600--5900 K reported by Israelian and
coworkers, as compared to 20 normal stars at the same temperature and
metallicity ranges. Our result indicates a higher probability of lithium
depletion for stars with planets in the main--sequence stage. It seems that
stellar photospheric abundances of lithium in stars with planets may be
somewhat affected by the presence of planets. Two possible mechanisms are
considered to account for the lower Li abundances of stars with planets. One is
related to the rotation-induced mixing due to the conservation of angular
momentum by the protoplanetary disk, and the other is a shear instability
triggered by planet migration. These results provide new information on stellar
evolution and the lithium evolution of the Galaxy.


title: Microquasars as sources of positron annihilation radiation

abstract:
  We consider the production of positrons in microquasars, i.e. X-ray binary
systems that exhibit jets frequently, but not continuously. We estimate the
production rate of positrons in microquasars, both by simple energy
considerations and in the framework of various proposed models. We then
evaluate the collective emissivity of the annihilation radiation produced by
Galactic microquasars and we find that it might constitute a substantial
contribution to the annihilation flux measured by INTEGRAL/SPI. We also discuss
the possible spatial distribution of Galactic microquasars, on the basis of the
(scarce) available data and the resulting morphology of the flux received on
Earth. Finally, we consider nearby 'misaligned' microquasars, with jets
occasionally hitting the atmosphere of the companion star; these would
represent interesting point sources, for which we determine the annihilation
flux and the corresponding light curve, as well as the line's spectral profile.
We discuss the possibility of detection of such point sources by future
instruments.


title: Mid-Infrared Spectroscopic Diagnostics of Galactic Nuclei

abstract:
  In this paper I summarize the science motivations, as well as a few
mid-infrared spectroscopic methods used to identify the principal mechanisms of
energy production in dust enshrouded galactic nuclei. The development of the
various techniques is briefly discussed. Emphasis is given to the use of the
data which are becoming available with the infrared spectrograph (IRS) on
Spitzer, as well as the results which have been obtained by IRS over the past
two years.


title: XMM-Newton survey of two Upper Scorpius regions

abstract:
  We study X-ray emission from young stars by analyzing deep XMM-Newton
observations of two regions of the Upper Scorpius association, having an age of
5 Myr. Based on near infrared and optical photometry we identify 22 Upper
Scorpius photometric members among the 224 detected X-ray sources. We derive
coronal properties of Upper Scorpius stars by performing X-ray spectral and
timing analysis. The study of four strong and isolated stellar flares allows us
to derive the length of the flaring loops. Among the 22 Upper Scorpius stars,
13 are identified as Upper Scorpius photometric members for the first time. The
sample includes 7 weak-line T Tauri stars and 1 classical T Tauri star, while
the nature of the remaining sources is unknown. Except for the intermediate
mass star HD 142578, all the detected USco sources are low mass stars of
spectral type ranging from G to late M. The X-ray emission spectrum of the most
intense Upper Scorpius sources indicates metal depleted plasma with temperature
of ~10 MK, resembling the typical coronal emission of active main sequence
stars. At least 59% of the detected members of the association have variable
X-ray emission, and the flaring coronal structures appear shorter than or
comparable to the stellar radii already at the Upper Scorpius age. We also find
indication of increasing plasma metallicity (up to a factor 20) during strong
flares. We identify a new galaxy cluster among the 224 X-ray source detected:
the X-ray spectrum of its intra cluster medium indicates a redshift of
0.41+/-0.02.


title: Photometry of the Magnetic White Dwarf SDSS 121209.31+013627.7

abstract:
  The results of 27 hours of time series photometry of SDSS 121209.31+013627.7
are presented. The binary period established from spectroscopy is confirmed and
refined to 0.061412 d (88.43 minutes). The photometric variations are dominated
by a brightening of about 16 mmag, lasting a little less than half a binary
cycle. The amplitude is approximately the same in V, R and white light. A
secondary small brightness increase during each cycle may also be present. We
speculate that SDSS 121209.31+013627.7 may be a polar in a low state.


title:
An angular power spectrum analysis of the DRAO 1.4 GHz polarization
  survey: implications for CMB observations

abstract:
  The aim of the present analysis is to improve the knowledge of the
statistical properties of the Galactic diffuse synchrotron emission, which
constrains sensitive CMB anisotropy measurements. We have analysed the new DRAO
1.4 GHz polarization survey together with the Stockert 1.4 GHz total intensity
survey and derived the angular power spectra (APSs) of the total intensity, the
polarized emission, and their cross-correlation for the entire surveys and for
three low-intensity regions. The APSs of the diffuse synchrotron emission are
modelled by power laws. For the $E$ and $B$ modes, a slope of $\alpha \sim
[-3.0,-2.5]$ for the multipole range $\sim [30,300]$ is found. By the
extrapolation of these results to 70 GHz, we can estimate the Galactic
synchrotron contamination of CMB anisotropies, and we find results that are
compatible with the ones coming from WMAP 3-yr data. In the low-intensity
regions, the cosmological primordial B~mode peak at $\ell \sim 100$ should be
clearly observable for a tensor-to-scalar ratio $T/S \gsim 0.5$ and a
synchrotron temperature spectral index $\beta \sim -3$. Its detection is also
possible for $T/S \gsim 0.005$ and $\beta \sim -3$, in case a separation of the
foreground from the CMB signal could be achieved with an accuracy of $\sim
5-10%$. For the TE mode, a mask excluding $|b_{gal}| \le 5^{\circ}$ (for
$\beta\sim -3.0$) or $|b_{gal}| \le 20^{\circ}$ (for $\beta\sim -2.8$) from the
surveys is sufficient to render the foreground contamination negligible, thus
confirming the ability of WMAP to have a clear view of the
temperature-polarization correlation peak and antipeak series.


title: Cosmological Constraints from Hubble Parameter versus Redshift Data

abstract:
  We use the Simon, Verde, & Jimenez (2005) determination of the redshift
dependence of the Hubble parameter to constrain cosmological parameters in
three dark energy cosmological models. We consider the standard $\Lambda$CDM
model, the XCDM parameterization of the dark energy equation of state, and a
slowly rolling dark energy scalar field with an inverse power-law potential.
The constraints are restrictive, consistent with those derived from Type Ia
supernova redshift-magnitude data, and complement those from galaxy cluster gas
mass fraction versus redshift data.


title: Bayesian Photometric Redshifts for Weak Lensing Applications

abstract:
  The next generation of weak gravitational lensing surveys is capable of
generating good measurements of cosmological parameters, provided that, amongst
other requirements, adequate redshift information is available for the
background galaxies that are measured. It is frequently assumed that
photometric redshift techniques provide the means to achieve this. Here we
compare Bayesian and frequentist approaches to photometric redshift estimation,
particularly at faint magnitudes. We identify and discuss the biases that are
inherent in the various methods, and describe an optimum Bayesian method for
extracting redshift distributions from photometric data.


title:
Detection of a Far-Infrared Bow-Shock Nebula Around R Hya: the First
  MIRIAD Results

abstract:
  We present the first results of the MIRIAD (MIPS [Multiband Imaging
Photometer for Spitzer] Infra-Red Imaging of AGB [asymptotic giant branch]
Dustshells) project using the Spitzer Space Telescope. The primary aim of the
project is to probe the material distribution in the extended circumstellar
envelopes (CSE) of evolved stars and recover the fossil record of their mass
loss history. Hence, we must map the whole of the CSEs plus the surrounding sky
for background subtraction, while avoiding the central star that is brighter
than the detector saturation limit. With our unique mapping strategy, we have
achieved better than one MJy/sr sensitivity in three hours of integration and
successfully detected a faint (< 5 MJy/sr), extended (~400 arcsec) far-infrared
nebula around the AGB star R Hya. Based on the parabolic structure of the
nebula, the direction of the space motion of the star with respect to the
nebula shape, and the presence of extended H alpha emission co-spatial to the
nebula, we suggest that the detected far-IR nebula is due to a bow shock at the
interface of the interstellar medium and the AGB wind of this moving star. This
is the first detection of the stellar-wind bow-shock interaction for an AGB
star and exemplifies the potential of Spitzer as a tool to examine the detailed
structure of extended far-IR nebulae around bright central sources. \


title:
Non-thermal intracluster medium: a simultaneous interpretation of the
  central soft X-ray excess and WMAP's detection of reduced Sunyaev-Zel'dovich
  Effect

abstract:
  WMAP's detection of the Sunyaev-Zel'dovich effect at a much reduced level
among several large samples of rich clusters is interpreted in terms of
conventional physics. It has been suggested that the central soft X-ray and EUV
excess found in some clusters cannot be of thermal origin, due to problems with
rapid gas cooling and the persistent non-detection of the O VII line, but may
arise from inverse-Compton scattering between intracluster relativistic
electrons and the cosmic microwave background. In fact, recent XMM observations
of the soft X-rays from Coma and Abell 3112 are equally well fitted by a power
law or a thermal virialized gas. Therefore the missing Sunyaev-Zel'dovich flux
could partly be due to an overestimate of the central density of virialized
electrons which scatter the CMB. Synchrotron radiation in an intracluster
magnetic field of strength of a few $\mu$G is responsible for significant
additional electron energy loss. Equipartition between relativistic particle
and magnetic field energy densities is a realistic possibility. GHz radiation
data from a Coma cluster halo yields information on the high energy steepening
of the cluster relativistic electron spectrum. Cluster microwave emission in
the WMAP passbands by higher energy cosmic ray electrons and gamma ray emission
from an accompanying cosmic ray proton flux are also considered. The energetic
electrons could originate from AGN jet injection, then distributed cluster-wide
by Alfven wave sweeping, with accompanying {\it in situ} Fermi acceleration.


title:
The possiblity of detection of Ultracool Dwarfs with the UKIRT Infrared
  Deep Sky Survey

abstract:
  We present predictions for the numbers of ultra--cool dwarfs in the Galactic
disk population that could be detected by the WFCAM/UKIDSS Large Area Survey
and Ultra Deep Survey. Simulated samples of objects are created with masses and
ages drawn from different mass functions and birthrates. Each object is then
given absolute magnitudes in different passbands based on empirically derived
bolometric correction vs. effective temperature relationships (or model
predictions for Y dwarfs). These are then combined with simulated space
positions, velocities and photometric errors to yield observables such as
apparent magnitudes and proper motions. Such observables are then passed
through the survey selection mechanism to yield histograms in colour. This
technique also produces predictions for the proper motion histograms for
ultra--cool dwarfs and estimated numbers for the as yet undetected Y dwarfs.
Finally it is shown that these techniques could be used to constrain the ultra
low--mass mass function and birthrate of the Galactic disk population


title: The Stellar Mass Density at z~6 from Spitzer Imaging of i-drop Galaxies

abstract:
  We measure the ages, stellar masses, and star formation histories of z~6
galaxies, observed within 1Gyr of the Big Bang. We use imaging from HST and
Spitzer from the public "Great Observatories Origins Deep Survey", coupled with
ground-based near-infrared imaging, to measure the spectral energy
distributions from 0.8-5microns, spanning the rest-frame UV and optical. From
our sample of ~50 i-drop Lyman-break star-forming galaxies in GOODS-South with
z'(AB)<27mag, we focus on ~30 with reliable photometric or spectroscopic
redshifts. Half of these are confused with foreground sources at Spitzer
resolution, but from the 16 with clean photometry we find that a surprisingly
large fraction (40%) have evidence for substantial Balmer-breaks. This
indicates the presence of old underlying stellar populations that dominate the
stellar masses. For these objects, we find ages of 200-700Myr, implying
formation redshifts of 7<z<14, and large stellar masses in the range
1-3x10^10M_sun. Analysis of 7 i-drops that are undetected at 3.6microns
indicates that these are younger, considerably less massive systems. We
calculate that line contamination should not severely affect our photometry or
derived results. Using data out to 8microns, we find little evidence for
substantial intrinsic dust reddening. Correcting for incompleteness in our
sample, we find a lower limit on the comoving stellar mass density at z~6 to be
2.5x10^6M_sun/Mpc^3. We are able to explore the star formation histories of our
selected galaxies, and we infer that the past global star formation rate may
have been much higher than that observed at z~6. The associated UV flux we
infer at z>7 could have played a major role in reionizing the universe.


title:
The X-ray synchrotron emission of RCW 86 and the implications for its
  age

abstract:
  We report here X-ray imaging spectroscopy observations of the northeastern
shell of the supernova remnant RCW 86 with Chandra and XMM-Newton. Along this
part of the shell the dominant X-ray radiation mechanism changes from thermal
to synchrotron emission. We argue that both the presence of X-ray synchrotron
radiation and the width of the synchrotron emitting region suggest a locally
higher shock velocity of V_s = 2700 km/s and a magnetic field of B = 24+/-5
microGauss. Moreover, we also show that a simple power law cosmic ray electron
spectrum with an exponential cut-off cannot explain the broad band synchrotron
emission. Instead a concave electron spectrum is needed, as predicted by
non-linear shock acceleration models. Finally, we show that the derived shock
velocity strengthens the case that RCW 86 is the remnant of SN 185.


title: Radial Velocity Studies of Southern Close Binary Stars.II

abstract:
  Radial-velocity measurements and sine-curve fits to the orbital velocity
variations are presented for 14 close binary stars, S Ant, TT Cet, TW Cet, AA
Cet, RW Dor, UX Eri, YY Eri, BV Eri, CT Eri, SZ Hor, AD Phe, TY Pup, HI Pup and
TZ Pyx. All are double-lined binaries and all except the last one are contact
binaries. The orbital data must be considered preliminary because of the
relatively small number of observations (6 - 12), a circumstance which is
partly compensated by the good definition of the broadening functions used for
the RV determinations.


title: RHESSI Observations of the Solar Flare Iron-line Feature at 6.7 keV

abstract:
  Analysis of RHESSI 3--10 keV spectra for 27 solar flares is reported. This
energy range includes thermal free--free and free--bound continuum and two line
features, at 6.7keV and 8keV, principally due to highly ionized iron (Fe). We
used the continuum and the flux in the so-called Fe-line feature at 6.7keV to
derive the electron temperature T_e, the emission measure, and the Fe-line
equivalent width as functions of time in each flare. The Fe/H abundance ratio
in each flare is derived from the Fe-line equivalent width as a function of
T_e. To minimize instrumental problems with high count rates and effects
associated with multi-temperature and nonthermal spectral components, spectra
are presented mostly during the flare decay phase, when the emission measure
and temperature were smoothly varying. We found flare Fe/H abundance ratios
that are consistent with the coronal abundance of Fe (i.e. 4 times the
photospheric abundance) to within 20% for at least 17 of the 27 flares; for 7
flares, the Fe/H abundance ratio is possibly higher by up to a factor of 2. We
find evidence that the Fe XXV ion fractions are less than the theoretically
predicted values by up to 60% at T_e=25 MK appear to be displaced from the most
recent theoretical values by between 1 and 3 MK.


title: Mass-Loaded Flows

abstract:
  A key process within astronomy is the exchange of mass, momentum, and energy
between diffuse plasmas in many types of astronomical sources (including
planetary nebulae, wind-blown bubbles, supernova remnants, starburst
superwinds, and the intracluster medium) and dense, embedded clouds or clumps.
This transfer affects the large scale flows of the diffuse plasmas as well as
the evolution of the clumps. I review our current understanding of
mass-injection processes, and examine intermediate-scale structure and the
global effect of mass-loading on a flow. I then discuss mass-loading in a
variety of diffuse sources.


title: Emission-line Diagnostics of Low Metallicity AGN

abstract:
  Current emission-line based estimates of the metallicity of active galactic
nuclei (AGN) at both high and low redshifts indicate that AGN have
predominantly solar to supersolar metallicities. This leads to the question: do
low metallicity AGN exist? In this paper we use photoionization models to
examine the effects of metallicity variations on the narrow emission lines from
an AGN. We explore a variety of emission-line diagnostics that are useful for
identifying AGN with low metallicity gas. We find that line ratios involving
[NII] are the most robust metallicity indicators in galaxies where the primary
source of ionization is from the active nucleus. Ratios involving [SII] and
[OI] are strongly affected by uncertainties in modelling the density structure
of the narrow line clouds. To test our diagnostics, we turn to an analysis of
AGN in the Sloan Digital Sky Survey (SDSS). We find a clear trend in the
relative strength of [NII] with the mass of the AGN host galaxy. The
metallicity of the ISM is known to be correlated with stellar mass in
star-forming galaxies; our results indicate that a similar trend exists for
AGN. We also find that the best-fit models for typical Seyfert narrow line
regions have supersolar abundances. Although there is a mass-dependent range of
a factor of 2-3 in the NLR metallicities of the AGN in our sample, AGN with
sub-solar metallicities are very rare in the SDSS. Out of a sample of ~23000
Seyfert 2 galaxies we find only ~40 clear candidates for AGN with NLR
abundances that are below solar.


title: Systematic Errors in Cosmic Microwave Background Interferometry

abstract:
  Cosmic microwave background (CMB) polarization observations will require
superb control of systematic errors in order to achieve their full scientific
potential, particularly in the case of attempts to detect the B modes that may
provide a window on inflation. Interferometry may be a promising way to achieve
these goals. This paper presents a formalism for characterizing the effects of
a variety of systematic errors on interferometric CMB polarization
observations, with particular emphasis on estimates of the B-mode power
spectrum. The most severe errors are those that couple the temperature
anisotropy signal to polarization; such errors include cross-talk within
detectors, misalignment of polarizers, and cross-polarization. In a B mode
experiment, the next most serious category of errors are those that mix E and B
modes, such as gain fluctuations, pointing errors, and beam shape errors. The
paper also indicates which sources of error may cause circular polarization
(e.g., from foregrounds) to contaminate the cosmologically interesting linear
polarization channels, and conversely whether monitoring of the circular
polarization channels may yield useful information about the errors themselves.
For all the sources of error considered, estimates of the level of control that
will be required for both E and B mode experiments are provided. Both
experiments that interfere linear polarizations and those that interfere
circular polarizations are considered. The fact that circular experiments
simultaneously measure both linear polarization Stokes parameters in each
baseline mitigates some sources of error.


title:
A Survey of Chromospheric Activity in the Solar-Type Stars in the Open
  Cluster M67

abstract:
  We present the results of a spectroscopic survey of the Ca II H & K core
strengths in a sample of 60 solar-type stars that are members of the solar-age
and solar-metallicity open cluster M67. We adopt the HK index, defined as the
summed H+K core strengths in 0.1 nm bandpasses centered on the H and K lines,
respectively, as a measure of the chromospheric activity that is present. We
compare the distribution of mean HK index values for the M67 solar-type stars
with the variation of this index as measured for the Sun during the
contemporary solar cycle. We find that the stellar distribution in our HK index
is broader than that for the solar cycle. Approximately 17% of the M67 sun-like
stars exhibit average HK indices that are less than solar minimum. About 7%-12%
are characterized by relatively high activity in excess of solar maximum values
while 72%-80% of the solar analogs exhibit Ca II H+K strengths within the range
of the modern solar cycle. The ranges given reflect uncertainties in the most
representative value of the maximum in the HK index to adopt for the solar
cycle variations observed during the period A.D. 1976--2004. Thus, ~ 20% - 30%
of our homogeneous sample of sun-like stars have mean chromospheric H+K
strengths that are outside the range of the contemporary solar cycle. Any
cycle-like variability that is present in the M67 solar-type stars appears to
be characterized by periods greater than ~ 6 years. Finally, we estimate a mean
chromospheric age for M67 in the range of 3.8--4.3 Gyr.


title:
Further Evidence for Variable Synchrotron Emission in XTE J1118+480 in
  Outburst

abstract:
  We present simultaneous multicolor infrared and optical photometry of the
black hole X-ray transient XTE J1118+480 during its short 2005 January
outburst, supported by simultaneous X-ray observations. The variability is
dominated by short timescales, ~10s, although a weak superhump also appears to
be present in the optical. The optical rapid variations, at least, are well
correlated with those in X-rays. Infrared JHKs photometry, as in the previous
outburst, exhibits especially large amplitude variability. The spectral energy
distribution (SED) of the variable infrared component can be fitted with a
power-law of slope alpha=-0.78 where Fnu is proportional to nu^alpha. There is
no compelling evidence for evolution in the slope over five nights, during
which time the source brightness decayed along almost the same track as seen in
variations within the nights. We conclude that both short-term variability, and
longer timescale fading, are dominated by a single component of constant
spectral shape. We cannot fit the SED of the IR variability with a credible
thermal component, either optically thick or thin. This IR SED is, however,
approximately consistent with optically thin synchrotron emission from a jet.
These observations therefore provide indirect evidence to support jet-dominated
models for XTE J1118+480 and also provide a direct measurement of the slope of
the optically thin emission which is impossible based on the average spectral
energy distribution alone.


title: Cosmological Information from Lensed CMB Power Spectra

abstract:
  Gravitational lensing distorts the cosmic microwave background (CMB)
temperature and polarization fields and encodes valuable information on
distances and growth rates at intermediate redshifts into the lensed power
spectra. The non-Gaussian bandpower covariance induced by the lenses is
negligible to l=2000 for all but the B polarization field where it increases
the net variance by up to a factor of 10 and favors an observing strategy with
3 times more area than if it were Gaussian. To quantify the cosmological
information, we introduce two lensing observables, characterizing nearly all of
the information, which simplify the study of non-Gaussian impact, parameter
degeneracies, dark energy models, and complementarity with other cosmological
probes. Information on the intermediate redshift parameters rapidly becomes
limited by constraints on the cold dark matter density and initial amplitude of
fluctuations as observations improve. Extraction of this information requires
deep polarization measurements on only 5-10% of the sky, and can improve Planck
lensing constraints by a factor of ~2-3 on any one of the parameters w_0, w_a,
Omega_K, sum(m_nu) with the others fixed. Sensitivity to the curvature and
neutrino mass are the highest due to the high redshift weight of CMB lensing
but degeneracies between the parameters must be broken externally.


title: Supernovae, Lensed CMB and Dark Energy

abstract:
  Supernova distance and primary CMB anisotropy measurements provide powerful
probes of the dark energy evolution in a flat universe but degrade
substantially once curvature is marginalized. We show that lensed CMB
polarization power spectrum measurements, accessible to next generation ground
based surveys such as SPTpol or QUIET, can remove the curvature degeneracy at a
level sufficient for the SNAP and Planck surveys and allow a measurement of
sigma(w_p)=0.03, sigma(w_a)=0.3 jointly with sigma(Omega_K)=0.0035. This
expectation assumes that the sum of neutrino masses is independently known to
better than 0.1 eV. This assumption is valid if the lightest neutrino is
assumed to have negligible mass in a normal neutrino mass hierarchy and is
potentially testable with upcoming direct laboratory measurements.


title:
Meteoritical and dynamical constraints on the growth mechanisms and
  formation times of asteroids and Jupiter

abstract:
  Peak temperatures inside meteorite parent bodies are closely linked to
accretion times. Most iron meteorites come from bodies that accreted <0.5 Myr
after CAIs formed and were melted by 26Al and 60Fe, probably inside 2 AU.
Chondrite groups accreted intermittently over 4 Myr starting 1 Myr after CAIs
formed when planetary embryos may already have formed at ~1 AU. Meteorite
evidence precludes accretion of late-forming chondrites on the surface of
early-formed bodies; instead chondritic and non-chondritic meteorites probably
formed in separate planetesimals. Maximum metamorphic temperatures in chondrite
groups correlate inversely with mean chondrule age, as expected for 26Al
heating. Dynamical models suggest that asteroids accreted before Jupiter.
Therefore Jupiter probably reached its current mass >3-5 Myr after CAIs formed.
This precludes formation of Jupiter via a gravitational instability <1 Myr
after the solar nebula formed, and strongly favors core accretion. Shocks
formed by gravitational instabilities in the disk, proto-Jupiter, or by
planetary embryos may have produced some chondrules. The minimum lifetime for
the solar nebula of 3-5 Myr inferred from CAI and chondrule ages may exceed the
median 3 Myr lifetime for protoplanetary disks, but is well within the total
1-10 Myr range. Shorter formation times for extrasolar planets may help to
explain why their orbits are unlike those of solar giant planets.


title:
Structure Generation by Irradiation: What can GLIMPSE teach us about the
  ISM structure?

abstract:
  Diffuse emission in the mid-infrared shows a wealth of structure, that lends
itself to high-resolution structure analysis of the interstellar gas. A large
part of the emission comes from polycyclic aromatic hydrocarbons, excited by
nearby ultra-violet sources. Can the observed diffuse emission structure be
interpreted as column density structure? We discuss this question with the help
of a set of model molecular clouds bathed in the radiation field of a nearby
O-star. The correlation strength between column density and ``observed'' flux
density strongly depends on the absolute volume density range in the region.
Shadowing and irradiation effects may completely alter the appearance of an
object. Irradiation introduces additional small-scale structure and it can
generate structures resembling shells around HII-regions in objects that do not
possess any shell-like structures whatsoever. Nevertheless, structural
information about the underlying interstellar medium can be retrieved. In the
more diffuse regime ($n({HI})\lesssim 100$cm$^{-3}$), flux density maps may be
used to trace the 3D density structure of the cloud via density gradients.
Thus, while caution definitely is in order, mid-infrared surveys such as
GLIMPSE will provide quantitative insight into the turbulent structure of the
interstellar medium.


title:
Effects of cold dark matter decoupling and pair annihilation on
  cosmological perturbations

abstract:
  Weakly interacting massive particles are part of the lepton-photon plasma in
the early universe until kinetic decoupling, after which time the particles
behave like a collisionless gas with nonzero temperature. The Boltzmann
equation for WIMP-lepton collisions is reduced to a Fokker-Planck equation for
the evolution of the WIMP distribution including scalar density perturbations.
This equation and the Einstein and fluid equations for the plasma are solved
numerically including the acoustic oscillations of the plasma before and during
kinetic decoupling, the frictional damping occurring during kinetic decoupling,
and the free-streaming damping occurring afterwards and throughout the
radiation-dominated era. An excellent approximation reduces the solution to
quadratures for the cold dark matter density and velocity perturbations. The
subsequent evolution is followed through electron pair annihilation and the
radiation-matter transition; analytic solutions are provided for both large and
small scales. For a 100 GeV WIMP with bino-type interactions, kinetic
decoupling occurs at a temperature $T_d=23$ MeV. The transfer function in the
matter-dominated era leads to an abundance of small cold dark matter halos;
with a smooth window function the Press-Schechter mass distribution is $dn/d\ln
M\propto M^{-1/3}$ for $M<10^{-4} (T_d/$10 MeV)$^{-3}$ M$_\odot$.


title: Isolated neutron stars: Magnetic fields, distances, and spectra

abstract:
  We present timing measurements, astrometry, and high-resolution spectra of a
number of nearby, thermally emitting, isolated neutron stars. We use these to
infer magnetic field strengths and distances, but also encounter a number of
puzzles. We discuss three specific ones in detail: (i) For RX J0720.4-3125 and
RX J1308.6+2127, the characteristic ages are in excess of 1~Myr, while their
temperatures and kinematic ages indicate that they are much younger; (ii) For
RX J1856.5-3754, the brightness temperature for the optical emission is in
excess of that measured at X-ray wavelengths for reasonable neutron-star radii;
(iii) For RX J0720.4-3125, the spectrum changed from an initially featureless
state to one with an absorption feature, yet there was only a relatively small
change in effective temperature. Furthermore, we attempt to see whether the
spectra of all seven sourced, in six of which absorption features have now been
found, can be understood in the context of strongly magnetised hydrogen
atmospheres. We find that the energies of the absorption features can be
reproduced, but that the featureless spectra of some sources, especially the
Wien-like high-energy tails, remain puzzling.


title: The Halpha, Hbeta and Hdelta lines in the spectrum RR Tauri

abstract:
  The results of spectroscopic study of Ae Herbig star RR Tau are reported. The
observations were carried out with a moderate resolution. In accordance with
the presented data the Halpha line exhibits a double-peaked emission profile.
The blue component is weaker than or equal to the red one. Variations of the
Halpha equivalent width by a factor of 4 - 5 were found. The structure of this
line also varies. On JD 2447148 a red absorption reversal of the Halpha profile
was observed. The Hbeta spectral line exhibited both emission and absorption.
On JD 2449664 the single-peak emission shifted to the short wavelength range of
the underlying absorption line and the red wing of the stellar line looked like
a red-shifted absorption component of medium strength. The Hdelta line was in
absorption.


title:
New insights on chemical evolution of galaxies: XMM-Newton observations
  of M82

abstract:
  We report on the ongoing data analysis of a very deep (~100 ks) XMM-Newton
observation of the starburst galaxy M82. We show some details of data analysis
and a few results from spatially-resolved spectroscopy with the EPIC cameras.
Since M82 is a bright object with a complex spectrum, the data reduction of
such a deep observation has posed many challenges both about the involved
astrophysical processes and the available data analysis techniques. Vertical
(with respect to the galaxy plane) abundance gradients are discovered. The
hints for an under-abundance of Oxygen stemming from our previous study are
confirmed. The hot X-ray emitting gas is shown to have a multi-temperature
distribution.


title: Detection of Giant Radio Pulses from the Pulsar PSR B0656+14

abstract:
  Giant pulses (GPs) have been detected from the pulsar PSR B0656+14. A pulse
that is more intense than the average pulse by a factor of 120 is encountered
approximately once in 3000 observed periods of the pulsar. The peak flux
density of the strongest pulse, 120 Jy, is a factor of 630 higher than that of
the average pulse. The GP energy exceeds the energy of the average pulse by up
to a factor of 110, which is comparable to that for other known pulsars with
GPs, including the Crab pulsar and the millisecond pulsar PSR B1937+21. The
giant pulses are a factor of 6 narrower than the average pulse and are
clustered at the head of the average pulse. PSR B0656+14 along with PSR
B0031-07, PSR B1112+50, and PSR J1752+2359 belong to a group of pulsars that
differ from previously known ones in which GPs have been detected without any
extremely strong magnetic field on the light cylinder.


title: High-z X-ray AGN Clustering and Cosmological Implications

abstract:
  I review recent results of the high-redshift X-ray selected AGN clustering,
based on the XMM/2dF survey. Using the luminosity-dependent density evolution
luminosity function we find that the spatial clustering lengths, derived using
Limber's inversion equation, are ~16 and ~19 h-1 Mpc respectively (for the
comoving clustering evolution model) while the median redshifts of the soft and
hard X-ray sources are z~ 1.2 and 0.75, respectively. Within the framework of
flat cosmological models we find that these results support a model with
Omega_m=0.26, \sigma_8=0.75, w=-0.9 (in excellent agreement with the 3 year
WMAP results). We also find the present day bias of X-ray AGNs to be b_o=2.


title: Mass and Environment Drive the Evolution of Early-Type Galaxies

abstract:
  New information has recently become available on the fundamental plane for
various samples of early-type galaxies with redshift up to 1.3, both in
clusters and in the field. This information is reviewed and clues are derived
on the evolution of spheroids over the last two thirds of the Universe lifetime
as a function of galaxy mass and environment, in comparison with the
predictions of the hierarchical models of galaxy formation. Using the Universe
as a time-machine and interpreting changes in M/L ratio as age differences, we
see that the age increases with galaxy mass in all environments, cluster
galaxies with any mass are older than field galaxies with the same mass, and
the age difference between cluster and field galaxies increases with mass. The
first two results confirm those obtained with other methods, and are reproduced
by the most recent incarnation of the hierarchical models, while the third
result is new and appears in contrast with the predictions of these models.


title:
Generating the Curvature Perturbation at the End of Inflation in String
  Theory

abstract:
  In brane inflationary scenarios, the cosmological perturbations are supposed
to originate from the vacuum fluctuations of the inflaton field corresponding
to the position of the brane. We show that a significant, and possibly
dominant, contribution to the curvature perturbation is generated at the end of
inflation through the vacuum fluctuations of fields, other than the inflaton,
which are light during the inflationary trajectory and become heavy at the
brane-anti brane annihilation. These fields appear generically in string
compactifications where the background geometry has exact or approximate
isometries and parametrize the internal angular directions of the brane.


title:
X-ray Radiation from the Annihilation of Dark Matter at the Galactic
  Center

abstract:
  The existing and upcoming multiwavelength data from the Galactic Center
suggest a comparative study in order to propose or rule out possible models
which would explain the observations. In this paper we consider the X-ray
synchrotron and the gamma-ray emission due to Kaluza Klein Dark Matter and
define a set of parameters for the shape of the Dark Matter halo which is
consistent with the observations. We show that for this class of models the
existing Chandra X-ray data is more restrictive than the constraints on very
high energy gamma-rays coming from HESS.


title:
Global structures in a composite system of two scale-free discs with a
  coplanar magnetic field

abstract:
  We investigate a theoretical MHD disc problem involving a composite disc
system of gravitationally coupled stellar and gaseous discs with a coplanar
magnetic field in the presence of an axisymmetric dark matter halo. The two
discs are expediently approximated as razor-thin, a ring-like magnetic field,
and a power-law rotation curve in radius . By imposing the scale-free
condition, we construct analytically stationary global MHD perturbation
configurations for both aligned and logarithmic spiral patterns. MHD
perturbation configurations in a composite system of partial discs in the
presence of an axisymmetric dark matter halo are also considered. We derive
analytically the stationary MHD dispersion relations for both aligned and
unaligned perturbation structures and analyze the corresponding phase
relationships between surface mass densities and the magnetic field. Compared
with earlier results, we obtain three solution branches corresponding to super
fast MHD density waves, fast MHD density waves and slow MHD density waves,
respectively. By evaluating the unaligned $m=0$ case, we determine the marginal
stability curves where the two unstable regimes corresponding to Jeans collapse
instability and ring fragmentation instability are identified. We find that the
aligned $m=0$ case is simply the limit of the unaligned $m=0$ case with the
radial wavenumber $\xi\to0$. We further show that a composite system of partial
discs behaves much differently from a composite system of full discs in certain
aspects. Our formalism provides a useful theoretical framework in the study of
stationary global perturbation configurations for MHD disc galaxies with bars,
spirals and barred spirals.


title:
Collapse of rotating stars in the Universe and the cosmic gamma ray
  bursts

abstract:
  We analyze here late evolutionary stages of massive (with initial mass higher
than 8 masses of the Sun) close binary stars. Our purposes are to study
possible mechanisms of gamma ray bursts (GRBs) origin. We suppose in this paper
that GRB phenomenon require formation of massive (approx. 1 M_sun) compact
(approx. 10 km) accretion disks around Kerr black holes and neutron stars. Such
Kerr black holes are products of collapse of Wolf-Rayet stars in extremely
close binaries and merging of neutron stars with black holes and neutron stars
with neutron stars in close binary systems. Required accretion disks also can
be formed around neutron stars which were formed during collapse of accreting
oxygen-neon white dwarfs. We have estimated frequencies of events which lead to
a rotational collapse concerned with formation of rapidly rotating relativistic
objects in the Galaxy. We made our calculations using the "Scenario Machine".


title:
The X-ray spectrum of the bursting atoll source 4U~1728-34 observed with
  INTEGRAL

abstract:
  We present for the first time a study of the 3-200 keV broad band spectra of
the bursting atoll source 4U 1728-34 (GX 354-0) along its hardness intensity
diagram. The analysis was done using the INTEGRAL public and Galactic Center
deep exposure data ranging from February 2003 to October 2004. The spectra are
well described by a thermal Comptonization model with an electron temperature
from 35 keV to 3 keV and Thomson optical depth, tau_T, from 0.5 to 5 in a slab
geometry. The source undergoes a transition from an intermediate/hard to a soft
state where the source luminosity increases from 2 to 12% of Eddington. We have
also detected 36 type I X-ray bursts two of which show photospheric radius
expansion. The energetic bursts with photospheric radius expansion occurred at
an inferred low mass accretion rate per unit area of \dot m ~ 1.7x10E3 g/cm2/s,
while the others at a higher one between 2.4x10E3 - 9.4x10E3 g/cm2/s. For
4U1728-34 the bursts' total fluence, and the bursts' peak flux are
anti-correlated with the mass accretion rate. The type I X-ray bursts involve
pure helium burning either during the hard state, or during the soft state of
the source.


title:
The nature and evolution of the highly ionized near-zones in the
  absorption spectra of z~6 quasars

abstract:
  We use state-of-the-art hydrodynamical simulations combined with a 1D
radiative transfer code to assess the extent to which the highly ionized
regions observed close to z~6 quasars, which we refer to as near-zones, can
constrain the ionization state of the surrounding IGM. We find the appearance
in Lya absorption of a quasar HII ionization front expanding into a neutral IGM
can be very similar to a classical proximity zone, produced by the enhancement
in ionizing flux close to a quasar embedded in a highly ionized IGM. The
observed sizes of these highly ionized near-zones and their redshift evolution
can be reproduced for a wide range of IGM neutral hydrogen fractions for
plausible values of the luminosity and lifetime of the quasars. The observed
near-zone sizes at the highest observed redshifts are equally consistent with a
significantly neutral and a highly ionized surrounding IGM. Stronger
constraints on the IGM neutral hydrogen fraction can be obtained by considering
the relative size of the near-zones in the Lya and Lyb regions of a quasar
spectrum. A large sample of high quality quasar absorption spectra with
accurate determinations of near-zone sizes and their redshift evolution in both
the Lya and Lyb regions should confirm or exclude the possibility that the
Universe is predominantly neutral at the highest observed redshifts. The width
of the discrete absorption features in these near-zones will contain important
additional information on the ionization state and the previous thermal history
of the IGM at these redshifts.


title: Dynamic Fibrils are driven by Magnetoacoustic Shocks

abstract:
  The formation of jets such as dynamic fibrils, mottles, and spicules in the
solar chromosphere is one of the most important, but also most poorly
understood, phenomena of the Sun's magnetized outer atmosphere. We use
extremely high-resolution observations from the Swedish 1-m Solar Telescope
combined with advanced numerical modeling to show that in active regions these
jets are a natural consequence of upwardly propagating slow mode
magnetoacoustic shocks. These shocks form when waves generated by convective
flows and global p-mode oscillations in the lower lying photosphere leak upward
into the magnetized chromosphere. We find excellent agreement between observed
and simulated jet velocities, decelerations, lifetimes and lengths. Our
findings suggest that previous observations of quiet sun spicules and mottles
may also be interpreted in light of a shock driven mechanism.


title: Observations of the Crab Nebula with H.E.S.S

abstract:
  The Crab nebula was observed with the H.E.S.S. stereoscopic
Cherenkov-telescope array between October 2003 and January 2005 for a total of
22.9 hours (after data quality selection). Observations were made with three
operational telescopes in late 2003 and with the complete 4 telescope array in
January - February 2004 and October 2004 - January 2005. The observations are
discussed and used as an example to detail the flux and spectral analysis
procedures of H.E.S.S., and to evaluate the systematic uncertainties in
H.E.S.S. flux measurements. The flux and spectrum of gamma-rays from the source
are calculated on run-by-run and monthly time-scales, and a correction is
applied for long-term variations in the detector sensitivity. Comparisons of
the measured flux and spectrum over the observation period, along with the
results from a number of different analysis procedures are used to estimate
systematic uncertainties in the measurements. The energy spectrum is found to
follow a power law with an exponential cutoff, with photon index $\Gamma = 2.39
\pm 0.03\stat$ and cutoff energy $E_{c} = (14.3 \pm 2.1\stat) \textrm{TeV}$
between 440 GeV and 40 TeV. The observed integral flux above 1 TeV is $(2.26
\pm 0.08\stat) \times 10^{-11} cm^{-2} s^{-1}$. The estimated systematic error
on the flux measurement is estimated to be 20%, while the estimated systematic
error on the spectral slope is 0.1.


title:
CMB anisotropies seen by an off-center observer in a spherically
  symmetric inhomogeneous universe

abstract:
  The current authors have previously shown that inhomogeneous, but spherically
symmetric universe models containing only matter can yield a very good fit to
the SNIa data and the position of the first CMB peak. In this work we examine
how far away from the center of inhomogeneity the observer can be located in
these models and still fit the data well. Furthermore, we investigate whether
such an off-center location can explain the observed alignment of the lowest
multipoles of the CMB map. We find that the observer has to be located within a
radius of 15 Mpc from the center for the induced dipole to be less than that
observed by the COBE satellite. But for such small displacements from the
center, the induced quadru- and octopoles turn out to be insufficiently large
to explain the alignment.


title: Signals from the Noise: Image Stacking for Quasars in the FIRST Survey

abstract:
  We present a technique to explore the radio sky into the nanoJansky regime by
employing image stacking using the FIRST survey. We first discuss the
non-intuitive relationship between the mean and median values of a distribution
that is dominated by noise, followed by an analysis of the systematic effects
present in FIRST's 20cm VLA snapshot images. Image stacking allows us to
recover the properties of source populations with fluxes a factor of 30 or more
below the rms noise level. Mean estimates of radio flux density, luminosity,
etc., are derivable for any source class having arcsecond positional accuracy.
  We use this technique to compute the mean radio properties for 41,295 quasars
from the SDSS DR3 catalog. There is a tight correlation between optical and
radio luminosity, with the radio luminosity increasing as the 0.85 power of
optical luminosity. This implies declining radio-loudness with optical
luminosity: the most luminous objects (M=-28.5) have average radio-to-optical
ratios 3 times lower than the least luminous objects (M=-20). There is also a
striking correlation between optical color and radio loudness: quasars that are
either redder or bluer than the norm are brighter radio sources, with objects
0.8 magnitudes redder than the SDSS composite spectrum having radio-loudness
ratios that are higher by a factor of 10. We explore the longstanding question
of whether a radio-loud/radio-quiet dichotomy exists in quasars, finding that
optical selection effects probably dominate the distribution function of radio
loudness, which has at most a modest (~20%) inflection between the radio-loud
and radio-quiet ends of the distribution. We also find, surprisingly, that
broad absorption line quasars have higher mean radio flux densities, with the
greatest disparity arising in the rare low-ionization BAL subclass.


title: An Activity Catalogue of Southern Stars

abstract:
  We have acquired high-resolution echelle spectra of 225 F6-M5 type stars in
the southern hemisphere. The stars are targets or candidates to be targets for
the Anglo-Australian Planet Search. CaII HK line cores were used to derive
activity indices for all of these objects. The indices were converted to the
Mt. Wilson system of measurements and logR'HK values determined. A number of
these stars had no previously derived activity indices. In addition we have
also included the stars from Tinney et al. (2002) using our Mt. Wilson
calibration. The radial-velocity instability (also known as jitter) level was
determined for all 21 planet-host stars in our dataset. We find the jitter to
be at a level considerably below the radial-velocity signatures in all but one
of these systems. 19 stars from our sample were found to be active (logR'HK >
-4.5) and thus have high levels of jitter. Radial-velocity analysis for
planetary companions to these stars should precede with caution.


title:
Intrinsic properties of the magnetically collimated water maser jet of
  W43A

abstract:
  Water maser polarization observations in the precessing jet of W43A have
revealed that it is magnetically collimated. Here we present a detailed
description of the physical properties of the water maser environment in the
jet. We discuss the maser saturation level and beaming angle as well as the
intrinsic temperatures and densities. Additionally, we show that the
polarization angle of the strongest red-shifted maser feature undergoes a fast
rotation of 90 degrees across the maser. Along with the variation of linear
polarization fraction, this strongly supports the current theoretical
description of maser linear polarization.


title:
Atmospheric Circulation of Close-In Extrasolar Giant Planets: I. Global,
  Barotropic, Adiabatic Simulations

abstract:
  We present results from a set of over 300 pseudospectral simulations of
atmospheric circulation on extrasolar giant planets with circular orbits. The
simulations are of high enough resolution (up to 341 total and sectoral modes)
to resolve small-scale eddies and waves, required for reasonable physical
accuracy. In this work, we focus on the global circulation pattern that emerges
in a shallow, ``equivalent-barotropic'', turbulent atmosphere on both tidally
synchronized and unsynchronized planets. A full exploration of the large
physical and numerical parameter-space is performed to identify robust features
of the circulation. For some validation, the model is first applied to Solar
System giant planets. For extrasolar giant planets with physical parameters
similar to HD209458b--a presumably synchronized extrasolar giant planet,
representative in many dynamical respects--the circulation is characterized by
the following features: 1) a coherent polar vortex that revolves around the
pole in each hemisphere; 2) a low number--typically two or three--of
slowly-varying, broad zonal (east-west) jets that form when the maximum jet
speed is comparable to, or somewhat stronger than, those observed on the
planets in the Solar System; and, 3) motion-associated temperature field, whose
detectability and variability depend on the strength of the net heating rate
and the global root mean square wind speed in the atmosphere. In many ways, the
global circulation is Earth-like, rather than Jupiter-like. However, if
extrasolar giant planets rotate faster and are not close-in (therefore not
synchronized), their circulations become more Jupiter-like, for Jupiter-like
rotation rates.


title: Constraints on Supersymmetric Models of Hybrid Inflation

abstract:
  We point out that the inclusion of a string component contributing around 5%
to the CMB power spectrum amplitude on large scales can increase the preferred
value of the spectral index n_s of density fluctuations measured by CMB
experiments. While this finding applies to any cosmological scenario involving
strings, we consider in particular models of supersymmetric hybrid inflation,
which predict n_s >= 0.98, in tension with the CMB data when strings are not
included. Using MCMC analysis we constrain the parameter space allowed for F-
and D-term inflation. For the F-term model, using minimal supergravity
corrections, we find that \log\kappa= -2.34\pm 0.38 and M= (0.518\pm 0.059) *
10^16 GeV. The inclusion of non-minimal supergravity corrections can modify
these values somewhat. In the corresponding analysis for D-term inflation, we
find \log\kappa= -4.24\pm 0.19 and m_FI= (0.245\pm 0.031) * 10^16 GeV. Under
the assumption that these models are correct, these results represent precision
measurements of important parameters of a Grand Unified Theory. We consider the
possible uncertainties in our measurements and additional constraints on the
scenario from the stochastic background of gravitational waves produced by the
strings. The best-fitting model predicts a B-mode polarization signal \approx
0.3 \mu K rms peaking at l \approx 1000. This is of comparable amplitude to the
expected signal due to gravitational lensing of the adiabatic E-mode signal on
these scales.


title:
Introducing Powell's Direction Set Method to a Fully Automated Analysis
  of Eclipsing Binary Stars

abstract:
  With recent observational advancements, substantial amounts of photometric
and spectroscopic eclipsing binary data have been acquired. As part of an
ongoing effort to assemble a reliable pipeline for fully automatic data
analysis, we put Powell's direction set method to the test. The method does not
depend on numerical derivatives, only on function evaluations, and as such it
cannot diverge. Compared to differential corrections (DC) and Nelder & Mead's
downhill simplex (NMS) method, Powell's method proves to be more efficient in
terms of solution determination and the required number of iterations. However,
its application is still not optimal in terms of time cost. Causes for this
deficiency are identified and two steps toward the solution are proposed:
non-ortogonality of the parameter set should be removed and better initial
directions should be determined before the minimization is initiated. Once
these setbacks are worked out, Powell's method will probably replace DC and NMS
as the default minimizing algorithm in PHOEBE modeling package.


title: Astrophysical Effects of Scalar Dark Matter Miniclusters

abstract:
  We model the formation, evolution and astrophysical effects of dark compact
Scalar Miniclusters (``ScaMs''). These objects arise when a scalar field, with
an axion-like or Higgs-like potential, undergoes a second order phase
transition below the QCD scale. Such a scalar field may couple too weakly to
the standard model to be detectable directly through particle interactions, but
may still be detectable by gravitational effects, such as lensing and baryon
accretion by large, gravitationally bound miniclusters. The masses of these
objects are shown to be constrained by the Ly$\alpha$ power spectrum to be less
than $\sim 10^4 M_\odot$, but they may be as light as classical axion
miniclusters, of the order of $10^{-12} M_\odot$. We simulate the formation and
nonlinear gravitational collapse of these objects around matter-radiation
equality using an N-body code, estimate their gravitational lensing properties,
and assess the feasibility of studying them using current and future lensing
experiments. Future MACHO-type variability surveys of many background sources
can reveal either high-amplification, strong lensing events, or measure density
profiles directly via weak-lensing variability, depending on ScaM parameters
and survey depth. However, ScaMs, due to their low internal densities, are
unlikely to be responsible for apparent MACHO events already detected in the
Galactic halo. A simple estimate is made of parameters that would give rise to
early structure formation; in principle, early stellar collapse could be
triggered by ScaMs as early as recombination, and significantly affect cosmic
reionization.


title:
Self-Similar Evolutionary Solutions of Self-Gravitating, Polytropic
  $\beta$-Viscous Disks

abstract:
  We carry out the effect of $\beta$-prescription for viscosity which
introduced by Duschel et al. 2000 & Hure, Richard & Zhan 2001, in a standard
self-gravitating thin disks. We were predicted in a self-gravitating thin disk
the $\beta$-model will have different dynamical behavior compare the well known
$\alpha$-prescriptions. We used self-similar methods for solving the integrated
equations which govern the dynamical behavior of the thin disks. We present the
results of self-similar solutions of the time evolution of axisymmetric,
polytropic, self-gravitating viscous disks around a new born central object. We
apply a $\beta$-viscosity prescription which has been derived from rotating
shear flow experiments ($\nu=\beta r^2\Omega$). Using reduced equations in a
slow accretion limit, we demonstrate inside-out self-similar solutions after
core formation in the center. Some physical quantities for $\beta$-disks are
determined numerically.We have compared our results with $\alpha$-disks under
the same initial conditions. It has been found that the accretion rate onto the
central object for $\beta$-disks more than $\alpha$-disks at least in the outer
regions where $\beta$-disks are more efficient. Our results show that Toomre
instability parameter is less than one everywhere on the $\beta$-disk which
means that in such disks gravitational instabilities can be occurred, so the
$\beta$-disk model can be a good candidate for the origin of planetary systems.
Our results show that the $\beta$-disks will decouple in the outer part of the
disk where the self-gravity plays an important role which is in agreement with
Duschl predictions.


title: Detecting Irregular Orbits in Gravitational N-body Simulations

abstract:
  We present a qualitative diagnostic based on the continuous wavelet
transform, for the detection of irregular behavior in time series of particle
simulations. We apply the method to three qualitatively different gravitational
3-body encounters. The intrinsic irregular behavior of these encounters is well
reproduced by the presented method, and we show that the method accurately
identifies the irregular regime in these encounters. We also provide an
instantaneous quantification for the degree of irregularity in these
simulations. Furthermore we demonstrate how the method can be used to analyze
larger systems by applying it to simulations with 100-particles. It turns out
that the number of stars on irregular orbits is systematically larger for
clusters in which all stars have the same mass compared to a multimass system.
The proposed method provides a quick and sufficiently accurate diagnostic for
identifying stars on irregular orbits in large scale N-body simulations.


title:
Inverse Compton Emission from Galactic Supernova Remnants: Effect of the
  Interstellar Radiation Field

abstract:
  The evidence for particle acceleration in supernova shells comes from
electrons whose synchrotron emission is observed in radio and X-rays. Recent
observations by the HESS instrument reveal that supernova remnants also emit
TeV gamma-rays; long awaited experimental evidence that supernova remnants can
accelerate cosmic rays up to the ``knee'' energies. Still, uncertainty exists
whether these gamma-rays are produced by electrons via inverse Compton
scattering or by protons via neutral pion decay. The multi-wavelength spectra
of supernova remnants can be fitted with both mechanisms, although a preference
is often given to neutral pion decay due to the spectral shape at very high
energies. A recent study of the interstellar radiation field indicates that its
energy density, especially in the inner Galaxy, is higher than previously
thought. In this paper we evaluate the effect of the interstellar radiation
field on the inverse Compton emission of electrons accelerated in a supernova
remnant located at different distances from the Galactic Centre. We show that
contribution of optical and infra-red photons to the inverse Compton emission
may exceed the contribution of cosmic microwave background and in some cases
broaden the resulted gamma-ray spectrum. Additionally, we show that if a
supernova remnant is located close to the Galactic Centre its gamma-ray
spectrum will exhibit a ``universal'' cutoff at very high energies due to the
Klein-Nishina effect and not due to the cut-off of the electron spectrum. As an
example, we apply our calculations to the supernova remnants RX J1713.7-3946
and G0.9+0.1 recently observed by HESS.


title: Self-Similar Collisionless Shocks

abstract:
  Observations of gamma-ray burst afterglows suggest that the correlation
length of magnetic field fluctuations downstream of relativistic non-magnetized
collisionless shocks grows with distance from the shock to scales much larger
than the plasma skin depth. We argue that this indicates that the plasma
properties are described by a self-similar solution, and derive constraints on
the scaling properties of the solution. For example, we find that the scaling
of the characteristic magnetic field amplitude with distance from the shock is
B \propto D^{s_B} with -1<s_B<=0, that the spectrum of accelerated particles is
dn/dE \propto E^{-2/(s_B+1)}, and that the scaling of the magnetic correlation
function is <B_i(x)B_j(x+dx)> \propto x^{2s_B} (for x>>D). We show that the
plasma may be approximated as a combination of two self-similar components: a
kinetic component of energetic particles and an MHD-like component representing
"thermal" particles. We argue that the latter may be considered as infinitely
conducting, in which case s_B=0 and the scalings are completely determined
(e.g. dn/dE \propto E^{-2} and B \propto D^0). Similar claims apply to non-
relativistic shocks such as in supernova remnants, if the upstream magnetic
field can be neglected. Self-similarity has important implications for any
model of particle acceleration and/or field generation. For example, we show
that the diffusion function in the angle \mu of momentum p in diffusive shock
acceleration models must satisfy D_{\mu\mu}(p,D) = D^{-1}D'_{\mu\mu}(p/D), and
that a previously suggested model for the generation of large scale magnetic
fields through a hierarchical merger of current-filaments should be
generalized. A numerical experiment testing our analysis is outlined
(Abridged).


title:
Damping and excitation variations of the solar acoustic modes using LOWL
  observations

abstract:
  We have used observations made with the helioseismic instrument LOWL
collected over $\sim$ 6 years to carry out an independent study of the
variations of the p-mode damping and excitation rates with solar activity. We
observe significant variations in the mode height, mode width and mode velocity
power over a wide range of angular degree values. Their sensitivities to solar
activity show clear evidence of frequency dependence, the modes in the
frequency range from 2700 and 3300 $\mu$Hz showing the largest variations and
exhibiting a maximum change centered around 3100 $\mu$Hz. As for the mode
energy supply rate, it is consistent, at the level of precision of the
observations, with a zero change along the solar cycle and over the range of
studied frequencies. Moreover, the variations with solar activity of each of
these parameters are observed to be more or less $\ell$-independent over the
range of studied angular degrees. Our results provide the first in-depth
confirmation of the findings obtained from GONG measurements for intermediate
angular degrees.


title:
Shaping bipolar Planetary Nebulae : How mass loss leads to waistline
  development

abstract:
  Asymptotic Giant Branch (AGB) stars generally have spherically symmetric
envelopes, whereas most post-AGB stars and Planetary Nebulae (PNe) show
axisymmetric circumstellar envelopes. While various mechanisms for axisymmetric
circumstellar structures may explain the shapes of PNe, they do not address how
the shape of the circumstellar shell evolves. Here we address the temporal
changes in the axisymmetry of AGB star envelopes, and in particular the
development of the torus required in the Generalized Interacting Stellar Winds
(GISW) model. Assuming (1) an AGB star rotates with sufficient angular speed at
the start of the AGB phase; and (2) that the rotational angular momentum of the
AGB star is conserved, we demonstrate that some very important observational
features of AGB star axisymmetry evolution can be reproduced. We find that,
compared to the star's increasing luminosity and decreasing effective
temperature, the decreasing mass of the star primarily affects the axisymmetry
of the envelope. When a representative mass loss history is adopted, where most
of the mass is lost near the end of the AGB phase, the envelope's axisymmetry
increases over time, with the strongest increase occurring near the end of the
AGB phase. This may naturally explain why most AGB stars have spherically
symmetric envelopes, while axisymmetry seems common-place in the post-AGB/PNe
phase. The degree of axisymmetry at the end of the AGB phase is found to
increase with increasing main sequence mass, and the onset of axisymmetry
occurs only after the onset of the superwind (SW) phase, in good agreement with
the observations.


title: Luminosity and redshift dependent quasar clustering

abstract:
  We present detailed clustering measurements for a flux limited sample of
14,000 quasars extracted from the 2dF QSO Redshift Survey (2QZ) in the redshift
range 0.8<z<2.1. After splitting the sample into three redshift bins and each
of them into six luminosity intervals, we estimate the quasar projected auto
and cross-correlation functions at a given redshift for separations 3 <
r/(Mpc/h) < 20. Fitting the data with a biased CDM model and using a
frequentist analysis (the F-test), we find that models with luminosity
dependent clustering are statistically favoured at the 95 per cent confidence
level for z>1.3. On the other hand, a number of tests based on information
theory and Bayesian statistics show only marginal evidence for luminosity
dependent clustering. Anyway, the quality of the data is not good enough to
accurately quantify how quasar biasing depends on luminosity. We critically
discuss the limitations of our dataset and show that a much larger sample is
needed to rule out current models for luminosity segregation. Studying the
evolution of the clustering amplitude with redshift, we detect an increase of
the quasar correlation length with lookback time at the 99.3 per cent
confidence level. Adopting the concordance cosmological model, we discuss the
evolution of quasar biasing with cosmic epoch and show that quasars are
typically hosted by dark matter haloes with mass ~10^{13} M_sol.


title:
Numerical simulations on the relative importance of starbursts and AGN
  in ultra-luminous infrared galaxies

abstract:
  We investigate the relative importance of starbursts and AGN in nuclear
activities of ultra-luminous infrared galaxies (ULIRGs) based on chemodynamical
simulations combined with spectrophotometric synthesis codes. We numerically
investigate both the gas accretion rates (m_acc) onto super massive black holes
(SMBHs) and the star formation rates (m_sf) in ULIRGs formed by gas-rich galaxy
mergers and thereby discuss what powers ULIRGs. Our principal results, which
can be tested against observations, are as follows. (1) ULIRGs powered by AGN
can be formed by major merging between luminous, gas-rich disk galaxies with
prominent bulges containing SMBHs, owing to the efficient gas fuelling m_acc >
1 M_sun/yr of the SMBH. AGN in these ULIRGs can be surrounded by compact
poststarburst stellar populations (e.g., A-type stars). (2) ULIRGs powered by
starbursts with m_sf ~ 100 M_sun/yr can be formed by merging between gas-rich
disk galaxies with small bulges having the bulge-to-disk-ratio (f_b) as small
as 0.1. (3) The relative importance of starbursts and AGN can depend on
physical properties of merger progenitor disks, such as f_b, gas mass fraction,
and total masses. For example, more massive galaxy mergers are more likely to
become AGN-dominated ULIRGs. (4) For most models, major mergers can become
ULIRGs, powered either by starbursts or by AGN, only when the two bulges
finally merge. Interacting disk galaxies can become ULIRGs with well separated
two cores (> 20kpc) at their pericenter when they are very massive and have
small bulges. (5) Irrespective of the choice of model, interacting/merging
galaxies show the highest accretion rates onto the central SMBHs, and the
resultant rapid growth of the SMBHs occur when their star formation rates are
very high.


title: Simple scaling laws for astrophysical jets

abstract:
  The idea of a unified model for all astrophysical jets has been considered
for quite some time. We present here a few scaling laws relevant to all type of
astrophysical jets, analogous to those of \citet{sams96} which are widely used
for astrophysical black holes. We use Buckingham's $ \Pi $ theorem of
dimensional analysis to obtain a family of dimensional relations among the
physical quantities associated to astrophysical jets.