title:
Inhomogeneous distribution of mercury on the surfaces of rapidly
  rotating HgMn stars

abstract:
  Starspots are usually associated with the action of magnetic fields at the
stellar surfaces. However, recently an inhomogeneous chemical distribution of
mercury was found for the mercury-manganese (HgMn) star alpha And -- a
well-established member of a non-magnetic subclass of the chemically peculiar
stars of the upper main sequence. In this study we present first results of the
high-resolution survey of the HgII 3984 resonance line in the spectra of
rapidly rotating HgMn stars with atmospheric parameters similar to those of
alpha And. We use spectrum synthesis modelling and take advantage of the
Doppler resolution of the stellar surfaces to probe horizontal structure of
mercury distribution. Clear signatures of spots are found in the HgII 3984 line
profiles of HR 1185 and HR 8723. Two observations of the latter star separated
by two days give evidence for the line profile variability. We conclude that
inhomogeneous distribution of Hg is a common phenomenon for the rapidly
rotating HgMn stars in the 13000--13800 K effective temperature range
independently of the stellar evolutionary stage. These results establish
existence of a new class of spectrum variable spotted B-type stars. It is
suggested that the observed Hg inhomogeneities arise from dynamical
instabilities in the chemical diffusion processes and are unrelated to magnetic
phenomena.


title:
Outflowing material in the CSS quasar 3C48: evidence of jet-cloud
  interaction?

abstract:
  We report the detection of a zabs=0.3654 associated absorption-line system in
the UV spectrum of the CSS quasar 3C48. The absorbing material is blue shifted
with respect to the quasar emission-line redshift, zem=0.3700, suggesting an
outflow velocity of ~1000 km/s. We detect absorption lines over a range of
ionization states from Ly-beta, Ly-gamma, CIV, NIV, SVI to OVI and possibly OIV
and NeVIII. The kinematical properties of the absorption-line system are
similar to the blue-shifted emission line gas seen in [OIII]\lambda5007
(Chatzichristou, Vanderriest & Jaffe 1999), which is believed to have
interacted with the radio jet. We study the properties of the absorbing
material using CLOUDY and find that photoionization models with Solar abundance
ratios (with overall metallicity in the range 0.1<Z/Z$_\odot$<1.3) are enough
to explain the observed column densities of all the species except NeVIII,
detection of which requires confirmation. Since the cooling and recombination
time for the gas is ~10^5 yr, the consistency with the photoionization models
suggests that any possible interaction of absorbing material with the jet must
have taken place before ~10^5 yr. The abundance ratio of nitrogen to carbon is
close to Solar values, unlike in the case of most quasars, especially at
high-redshifts, which have super-Solar values. We observed 3C48 with the Giant
Metrewave Radio Telescope (GMRT) to search for redshifted 21cm HI absorption.
However, we did not detect any significant feature in our spectra and estimate
the 3-sigma upper limit to the optical depth to be in the range 0.001 to 0.003.
However, due to the diffuse nature of the radio source, optical depths as high
as 0.1 towards individual knots or compact components cannot be ruled out.


title: Molecular Hydrogen Emission from Protoplanetary Disks

abstract:
  We have modeled self-consistently the density and temperature profiles of gas
and dust in protoplanetary disks, taking into account irradiation from a
central star. Making use of this physical structure, we have calculated the
level populations of molecular hydrogen and the line emission from the disks.
As a result, we can reproduce the observed strong line spectra of molecular
hydrogen from protoplanetary disks, both in the ultraviolet (UV) and the
near-infrared, but only if the central star has a strong UV excess radiation.


title: Blueshifted [O III] Emission: Indications of a Dynamic NLR

abstract:
  The [O III] 5007 line is commonly used as an indicator of the systemic
redshift of AGNs. Also, recent studies have used the width of this emission
line as a proxy for the stellar velocity dispersion in the host galaxy. This
paper calls both of these assumptions into question by analyzing a sample of
approximately 400 AGN spectra from the first data release of the Sloan Digital
Sky Survey. These spectra show that the low-ionization forbidden lines ([O II],
[N II], [S II]) define a consistent redshift, but that the peak of the [O III]
line is blueshifted in approximately half of the AGNs with respect to that
redshift. For the sample studied here, the average shift is 40 km/s, with the
largest shift being over 400 km/s. The magnitude of this shift is found to be
correlated with a number of properties, including the width of the [O III] line
and the Eddington ratio (L/L$_{Edd}$), derived from the luminosity and width of
H-beta.


title: Improved Templates for Photometric Redshifts of Submm Sources

abstract:
  There is growing evidence that some star-forming galaxies at z>1 are
characterized by high efficiencies and specific star formation rates. In the
local universe, these traits are shared by ``active'' Blue Compact Dwarf
galaxies (BCDs) with compact and dense star-forming regions. The Spectral
Energy Distributions (SEDs) of these BCDs are dominated by young massive star
clusters, embedded in a cocoon of dust. In this Letter, we incorporate these
BCD SEDs as templates for two samples of high-redshift galaxy populations
selected at submm wavelengths. Because of the severe absorption of the optical
light, the featureless mid-infrared spectrum, and the relatively flat radio
continuum, the dusty star-cluster SEDs are good approximations to most of the
submm sources in our samples. In most cases, the active BCD SEDs fit the
observed photometric points better than the ``standard'' templates, M 82 and
Arp 220, and predict photometric redshifts significantly closer to the
spectroscopic ones. Our results strongly suggest that the embedded dusty star
clusters in BCD galaxies are superior to other local templates such as M 82 and
Arp 220 in fitting distant submm starburst galaxies.


title:
Spectral Formation in X-Ray Pulsars: Bulk Comptonization in the
  Accretion Shock

abstract:
  Accretion-powered X-ray pulsars are among the most luminous X-ray sources in
the Galaxy. However, despite decades of theoretical and observational work
since their discovery, no satisfactory model for the formation of the observed
X-ray spectra has emerged. In particular, the previously available theories are
unable to reproduce the power-law variation observed at high energies in many
sources. In this paper, we present the first self-consistent calculation of the
spectrum emerging from a pulsar accretion column that includes an explicit
treatment of the energization occurring in the shock. Using a rigorous
eigenfunction expansion method based on the exact dynamical solution for the
velocity profile in the column, we obtain a closed-form expression for the
Green's function describing the upscattering of radiation injected into the
column from a monochromatic source located at the top of the thermal mound,
near the base of the flow. The Green's function is convolved with a Planck
distribution to calculate the radiation spectrum resulting from the
reprocessing of blackbody photons emitted by the thermal mound. We demonstrate
that the energization of the photons in the shock naturally produces an X-ray
spectrum with a power-law shape at high energies and a blackbody shape at low
energies, in agreement with many observations of accreting X-ray pulsars.


title: Multi-Phase Galaxy Formation and Quasar Absorption Systems

abstract:
  The central problem of galaxy formation is understanding the cooling and
condensation of gas in dark matter halos. It is now clear that to match
observations this requires further physics than the simple assumptions of
single phase gas cooling. A model of multi-phase cooling (Maller & Bullock
2004) can successfully account for the upper cutoff in the masses of galaxies
and provides a natural explanation of many types of absorption systems (Mo &
Miralda-Escude 1996).
  Absorption systems are our best probes of the gaseous content of galaxy halos
and therefore provide important constraints on models for gas cooling into
galaxies. All physical processes that effect gas cooling redistribute gas and
therefore are detectable in absorption systems. Detailed studies of the nature
of gas in galaxy halos using absorption systems are crucial for building a
correct theory of galaxy formation.


title: The Nature of Dark Matter

abstract:
  The observed strong dark-to-luminous matter coupling suggests the existence
of a some functional relation between visible and DM sources which leads to
biased Einstein equations. We show that such a bias appears in the case when
the topological structure of the actual Universe at very large distances does
not match properly that of the Friedman space. We introduce a bias operator
$\rho_{DM} = B \rho_{vis}$ and show that the simple bias function $b \~1/r^{2}$
(the kernel of $B$) allows to account for all the variety of observed DM halos
in astrophysical systems. In galaxies such a bias forms the cored DM
distribution with the radius $R_{C}\sim R_{opt}$ (which explains the recently
observed strong correlation between $R_{C}$ and $R_{opt}$), while for a point
source it produces the logarithmic correction to the Newton's potential (which
explains the observed flat rotation curves in spirals). Finally, we show that
in the theory suggested the galaxy formation process leads to a specific
variation with time of all interaction constants and, in particular, of the
fine structure constant.


title:
Anti-de Sitter curvature radius constrained by quasars in brane-world
  scenarios

abstract:
  This paper is intended to investigate the luminosity due to accretion of gas
in supermassive black holes (SMBHs) in the center of quasars, using a
brane-world scenario naturally endowed with extra dimensions, whereon theories
formulated introduce corrections in the field equations at high energies. SMBHs
possess the necessary highly energetic environment for the introduction of
these corrections, which are shown to produce small deviations in all SMBH
properties and, consequentely, corrections in the accretion theory that
supports quasars radiative processes. The radiative flux observed from quasars
indicates these deviations, from which the magnitude of the AdS$_5$ bulk
curvature radius, and consequently the extra dimension compactification radius
is estimated.


title:
Effective equation of state for dark energy: mimicking quintessence and
  phantom energy through a variable Lambda

abstract:
  While there is mounting evidence in all fronts of experimental cosmology for
a non-vanishing dark energy component in the Universe, we are still far away
from understanding its ultimate nature. A fundamental cosmological constant,
Lambda, is the most natural candidate, but many dynamical mechanisms to
generate an effective Lambda have been devised which postulate the existence of
a peculiar scalar field (so-called quintessence, and generalizations thereof).
These models are essentially ad hoc, but they lead to the attractive
possibility of a time-evolving dark energy with a non-trivial equation of state
(EOS). Most, if not all, future experimental studies on precision cosmology
(e.g. the SNAP and PLANCK projects) address very carefully the determination of
an EOS parametrized ``a la quintessence''. Here we show that by fitting
cosmological data to an EOS of that kind can also be interpreted as a hint of a
fundamental, but time-evolving, cosmological term: Lambda=Lambda(t). We
exemplify this possibility by studying the effective EOS associated to a
renormalization group (RG) model for Lambda. We find that the effective EOS can
correspond to both normal quintessence and phantom dark energy, depending on
the value of a single parameter of the RG model. We conclude that behind a
non-trivial EOS of a purported quintessence or phantom scalar field there can
actually be a running cosmological term of a fundamental quantum field theory.


title:
Towards an Understanding of the Physical Nature of MgII Absorption
  Systems

abstract:
  We discuss issues concerning the physical nature of intervening MgII quasar
absorption systems in light of results from our recent surveys using SDSS EDR
QSO spectra and data obtained at the MMT. These surveys indicate an excess of
weak $W_0^{\lambda2796} \lesssim 0.3$\AA) systems relative to the exponential
dN/dW distribution of stronger systems. The incidence of intermediate-strength
lines shows remarkably little evolution with redshift, thereby constraining
models for the nature of the clouds comprising these absorbers. The total
distribution does evolve, with the incidence decreasing with decreasing
redshift in a $W_0^{\lambda2796}$-dependent rate (the strongest systems evolve
the fastest). This suggests that multiple populations that evolve at different
rates contribute to the incidence in a $W_0^{\lambda2796}$-dependent manner. We
also present two images of fields containing unprecedented ``ultra-strong''
($W_0^{\lambda2796} \ge 4.0$\AA) MgII absorbers.


title:
Ionization fronts and their interaction with density fluctuations:
  implications for reionization

abstract:
  The propagation of cosmological ionization fronts (I-fronts) during
reionization is strongly influenced by small-scale structure. Here we summarize
our recent attemps to understand the effect of this small-scale structure. We
present high resolution cosmological N-body simulations at high-z (z>6) which
resolve a wide range of halo mass, from minihalos to clusters of large, rare
halos. We also study how minihalos affect I-fronts, through simulations of
minihalo photoevaporation. Furthermore, we modify the I-front propagation
equations to account for evolving small-scale structure, and incorporate these
results into a semi-analytical reionization model. When intergalactic medium
clumping and minihalo clustering around sources are included, small-scale
structure affects reionization by slowing it down and extending it in time.
This helps to explain observations by the Wilkinson Microwave Anisotropy Probe,
which imply an early and extended reionization epoch. We also study how source
clustering affects the evolution and size of H II regions, finding, in
agreement with simulations, that H II regions usually expand, rarely shrinking.
Hence, "relic H II regions'' are an exception, rather than the rule. When the
suppression of small-mass sources in already-ionized regions by Jeans-mass
filtering is accounted for, H II regions are smaller, delaying overlap. We also
present a new numerical method for radiative transfer which is fast, efficient,
and easily coupled to hydrodynamics and N-body codes, along with sample tests
and applications.


title:
Black Hole Formation from Collapsing Dust Fluid in a Background of Dark
  Energy

abstract:
  The gravitational collapse of a spherically symmetric star, made of a dust
fluid, $\rho_{DM}$, in a background of dark energy, $p = w\rho,\; (w < -1/3)$,
is studied. It is found that when only dark energy is present, black holes are
{\em never} formed. When both of them are present, black holes can be formed,
due to the condensation of the dust fluid. Initially the dust fluid may not
play an important role, but, as time increases, it will dominate the collapse
and finally leads to formation of black holes. This result remains true even
when the interaction between the dust fluid and dark energy does not vanish.
When $w < -1$ (phantoms), some models can also be interpreted as representing
the death of a white hole that ejects both dust and phantoms. The ejected
matter re-collapses to form a black hole.


title:
Near-Infrared Photometry of the High-Redshift Quasar RDJ030117+002025:
  Evidence for a Massive Starburst at z=5.5

abstract:
  With a redshift of z=5.5 and an optical blue magnitude M_B ~ -24.2 mag (~4.5
10^12 L_sun), RDJ030117+002025 is the most distant optically faint (M_B > -26
mag) quasar known. MAMBO continuum observations at lambda=1.2 mm (185
micrometer rest-frame) showed that this quasar has a far-IR luminosity
comparable to its optical luminosity. We present near-infrared J- and K-band
photometry obtained with NIRC on the Keck I telescope, tracing the slope of the
rest frame UV spectrum of this quasar. The observed spectral index is close to
the value of alpha_nu ~ -0.44 measured in composite spectra of optically-bright
SDSS quasars. It thus appears that the quasar does not suffer from strong dust
extinction, which further implies that its low rest-frame UV luminosity is due
to an intrinsically-faint AGN. The FIR to optical luminosity ratio is then much
larger than that observed for the more luminous quasars, supporting the
suggestion that the FIR emission is not powered by the AGN but by a massive
starburst.


title:
Tightening Constraints from the Lyman Alpha Forest with the Flux
  Probability Distribution Function

abstract:
  The analysis of the Lyman-alpha forest of absorption lines in quasar spectra
has emerged as a potentially powerful technique to constrain the linear matter
power spectrum. In most previous work, the amplitude of the ionizing background
was fixed by calibrating simulations to match the observed mean transmitted
flux in the Lyman-alpha forest. This procedure is undesirable in principle as
it requires the estimation of the unabsorbed quasar continuum level, a
difficult undertaking subject to various sources of systematic error and bias.
We suggest an alternative approach based on measuring the one-point probability
distribution function (pdf) of the fluctuations in the flux about the mean,
relative to the mean, i.e. the pdf of delta_f = (f - <f>)/<f>. This statistic,
while sensitive to the amplitude of the ionizing background, has the virtue
that its measurement does not require an estimate of the unabsorbed continuum
level. We present a measurement of the pdf of delta_f from seven Keck HIRES
spectra, spanning a redshift range of z = 2.2 - 4.4. To illustrate that our
method is useful, we compare our measurements of the pdf of delta_f, and
measurements of the flux power spectrum from Croft et al. (2002) at z = 2.72,
with cosmological simulations. From this comparison, we obtain constraints on
the mean transmission in the Lyman-alpha forest, the slope of the
temperature-density relation, as well as the amplitude and slope of the mass
power spectrum. Our methodology will be useful for obtaining more precise
constraints with larger data samples from the Sloan Digital Sky Survey (SDSS).


title:
Chemical Composition in the Globular Cluster M71 from Keck/HIRES Spectra
  of Turn-Off Stars

abstract:
  We have made observations with the Keck I telescope and HIRES at a resolution
of $\sim$45,000 of five nearly identical stars at the turn-off of the
metal-rich globular cluster M 71. Our mean Fe abundance, [Fe/H]=-0.80 +-0.02,
is in excellent agreement with previous cluster determinations from both giants
and near-turnoff stars. There is no clear evidence for any star-to-star
abundance differences or correlations in our sample. Abundance ratios of the
Fe-peak elements (Cr, Ni) are similar to Fe. The turn-off stars in M71 have
remarkably consistent enhancements of 0.2 - 0.3 dex in [Si/Fe], [Ca/Fe] and
[Ti/Fe] -- like the red giants. Our [Mg/Fe] ratio is somewhat lower than that
suggested by other studies. We compare our mean abundances for the five M 71
stars with field stars of similar [Fe/H] -- 8 with halo kinematics and 17 with
disk kinematics. The abundances of the alpha-fusion products (Mg, Si, Ca, Ti)
agree with both samples, but seem a closer match to the disk stars. The Mg
abundance in M71 is at the lower edge of the disk and halo samples. The
neutron-capture elements, Y and Ba, are enhanced relative to solar in the M71
turn-off stars. Our ratio [Ba/Fe] is similar to that of the halo field stars
but a factor of two above that for the disk field stars. The important [Ba/Y]
ratio is significantly lower than M71 giant values. The Na content of the M71
turn-off stars is remarkably similar to that in the disk field stars, but more
than a factor of two higher than the halo field star sample. We find [Na/Fe] =
+0.14 $\pm$0.04 with a spread less than half of that found in the red giants in
M71. Excluding Mg, the lack of intracluster $\alpha$-element variations
(turn-off vs giants) suggests the polluting material arose in a more
traditional $s$-process environment such as AGB stars.


title:
Transrelativistic Synchrotron Emissivity, Cross-Section, and
  Polarization

abstract:
  The spectrum and polarization produced by particles spiraling in a magnetic
field undergo dramatic changes as the emitters transition from nonrelativistic
to relativistic energies. However, none of the currently available methods for
calculating the characteristics of this radiation field are adequate for the
purpose of sustaining accuracy and speed of computation in the intensity, and
none even attempt to provide a means of determining the polarization fraction
other than in the cyclotron or synchrotron limits. But the transrelativistic
regime, which we here find to lie between $5\times 10^7$ K and $5\times 10^9$ K
for a thermal plasma, is becoming increasingly important in high-energy
astrophysical environments, such as in the intra-cluster medium, and in the
accretion flows of supermassive black holes. In this paper, we present simple,
yet highly accurate, fitting formulae for the magnetobremsstrahlung (also known
as cyclo-synchrotron) emissivity, its polarization fraction (and content), and
the absorption cross-section. We demonstrate that both the harmonic and
high-energy limiting behavior are well represented, incurring at most an error
of $\sim 5%$ throughout the transition region.


title:
VLBA Identification of the Milliarcsecond Active Nucleus in the Seyfert
  Galaxy NGC 4151

abstract:
  The Seyfert galaxy NGC 4151 has been imaged at resolution better than 0.1 pc
using a VLBI array consisting of the VLBA and three 100m-class telescopes. A
flat-spectrum 3-mJy source with a monochromatic radio power of ~10^{37} ergs/s
has been detected, apparently at the location of the active galactic nucleus
(AGN) and its central black hole. The radio source has a minimum brightness
temperature of 2.1 x 10^8 K and a size upper limit of 0.035 pc, about 10 times
the diameter of the broad-line region and 15,000 times the diameter of the
black hole's event horizon. An additional flat-spectrum component located
within a parsec of the apparent nucleus is likely to be a knot in the inner
radio jet. The presence of some steep-spectrum radio emission within 0.1 pc of
the galaxy nucleus limits the emission measure of a possible ionized torus to a
maximum value of 10^8 cm^{-6}pc. If the hard X-ray source in NGC 4151 is
associated with the radio AGN, its radio to X-ray ratio is less than 10^{-5},
putting NGC 4151 securely in the radio-quiet class of AGNs. The radio image
reveals a 0.2 pc two-sided base to the well-known arcsecond radio jet. Apparent
speeds of jet components relative to the radio AGN are <0.050c and <0.028c at
respective nuclear distances of 0.16 pc and 6.8 pc. These are the lowest speed
limits yet found for a Seyfert galaxy, and indicate non-relativistic jet
motions, possibly due to thermal plasma, on a scale only an order of magnitude
larger than the broad-line region.


title: The phase-space distribution of infalling dark matter subhalos

abstract:
  We use high-resolution numerical simulations to study the physical properties
of subhalos when they merge into their host halos. An improved algorithm is
used to identify the subhalos. We then examine their spatial and velocity
distributions in spherical and triaxial halo models. We find that the accretion
of satellites preferentially occurs along the major axis and perpendicular to
the spin axis of the host halo. Furthermore, the massive subhalos show a
stronger preference to be accreted along the major axis of the host halo than
the low-mass ones. Approximate fitting formulae are provided for the physical
properties of subhalos. Combined with analytical and semi-analytic techniques,
these empirical formulae provide a useful basis for studying the subsequent
evolution of subhalos and satellite galaxies in their hosts. Future studies
should however account for satellites that may not be undergoing the first
infall in their evolution.


title:
The Temperature Distribution of Dense Molecular Gas in the Center of NGC
  253

abstract:
  [abridged] We present interferometric maps of ammonia (NH3) of the nearby
starburst galaxy NGC 253 [star formation rate: ~2.8 Mo yr^(-1)]. The
observations have been taken with the Australia Telescope Compact Array and
include the para-NH3 (1,1), (2,2), and the ortho-NH3 (3,3) and (6,6) inversion
lines. Six major complexes of dense ammonia are identified, three of them on
either side of the starburst center, out to projected galactocentric radii of
\~250 pc. [...] The application of radiative transfer large velocity gradient
models reveals that the bulk of the ammonia molecules is embedded in a
one-temperature gas phase. Kinetic temperatures of this gas are ~200 and 140 K
toward the south-west and north-east [of the nucleus of NGC 253], respectively.
The temperatures under which ammonia was formed in the past are with >~30 K
also warmer toward the south-west than toward the north-east (~15-20 K). This
is indicated by the ortho-to-para ammonia ratio which is ~1 and 1.5-2.5 toward
the south-west and north-east, respectively. Ammonia column densities in the
brightest complexes are in the range of 6-11x10^(14) cm^(-2), which adds up to
a total ammonia mass of ~20 Mo, about evenly distributed toward both sides of
the nucleus. [...] Toward the center of NGC 253, NH3 (1,1), (2,2), and (6,6) is
detected in absorption against an unresolved continuum source. At the same
location, however, ammonia (3,3) is found in emission which indicates maser
activity. This would be the first detected extragalactic NH3 maser. Evidence
for an expanding shell in the south-western complex is provided. [...] The
shell and X-ray properties can be reproduced by the energy input of a highly
obscured young stellar cluster with a mass of ~10^5 Mo which also heats the
dense gas.


title: Evolving turbulence and magnetic fields in galaxy clusters

abstract:
  We discuss, using simple analytical models and MHD simulations, the origin
and parameters of turbulence and magnetic fields in galaxy clusters. Three
physically distinct regimes can be identified in the evolution of cluster
turbulence and magnetic fields. Firstly, the fluctuation dynamo will produce
microgauss-strong, random magnetic fields during cluster formation and major
mergers. Turbulent velocity of about 300 km/s can be maintained at scales
100-200 kpc. The magnetic field is intermittent, has a smaller scale of 20-30
kpc and average strength of 2 microgauss. Secondly, when major mergers end,
turbulent speed and magnetic field undergo a power-law decay, decreasing in
strength but increasing in scale by a factor of about two. Thirdly,
smaller-mass subclusters and cluster galaxies produce turbulent wakes, with
turbulent speeds and magnetic field strengths similar to those quoted above.
The velocity scales are about 200 kpc and 10 kpc respectively, and the magnetic
field scale is about 6 times smaller. Although these wakes may fill only a
small fraction of the cluster volume, their area covering factor can be close
to unity. So one can potentially reconcile observations that indicate the
coexistence of turbulence with ordered filamentary gas structures, as in the
Perseus cluster. Random Faraday rotation measure is estimated to be typically
100-200 rad/m^2, in agreement with observations. We predict detectable
synchrotron polarization from cluster radio halos at wavelengths 3-6 cm, if
observed at sufficiently high resolution (abridged).


title:
Discovery of a Radio Supernova Remnant and Non-thermal X-rays Coincident
  with the TeV Source HESS J1813-178

abstract:
  We present the discovery of non-thermal radio and X-ray emission positionally
coincident with the TeV $\gamma$-ray source HESS J1813--178. We demonstrate
that the non-thermal radio emission is due to a young shell-type supernova
remnant (SNR) G12.8--0.0, and constrain its distance to be greater than 4 kpc.
The X-ray emission is primarily non-thermal and is consistent with either an
SNR shell or unidentified pulsar/pulsar wind nebula origin; pulsed emission is
not detected in archival ASCA data. A simple synchrotron+inverse Compton model
for the broadband emission assuming that all of the emission arises from the
SNR shell implies maximum energies of $(30-450)(B/10 microG)^{-0.5}$ TeV.
Further observations are needed to confirm that the broadband emission has a
common origin and better constrain the X-ray spectrum.


title: Radio Emission from Anisotropic Electron Distributions

abstract:
  The effect of pitch-angle anisotropy of fast electrons on generation of
nonthermal radio emission is studied. Incoherent gyrosynchrotron radiation is
shown to depend strongly on the anisotropy. In particular, the spectral index
of gyrosynchrotron radiation increases up to a factor of 3-4 compared with the
isotropic case. The degree of polarization (X-mode) increases for loss-cone
distributions, while decreases for beam-like distributions. Ample evidence of
the pitch-angle anisotropy effect on (1) spatial distribution of the radio
brightness, (2) spatially resolved light curves of the intensity and
polarization, (3) spectral hardness of microwave bursts, is found by exploring
observations performed with Nobeyama Radioheliograph and Owens Valley Solar
Array. Above some threshold in the angular gradient, the electron cyclotron
maser instability (coherent gyrosynchrotron emission) can develop, provided
that standard gyrosynchrotron emission is accompanied by a lower-frequency
intense coherent emission. The coherent emission is studied in detail for a
realistic distribution of fast electrons over the energy and pitch-angle. In
agreement with observations of narrowband radio spikes, it is found that (1)
hard (power-law) distributions over energy are preferable to produce the
coherent emission, (2) the threshold of the instability corresponds to quite an
anisotropic electron distribution, thus, the pitch-angle anisotropy derived
from the properties of the continuum gyrosynchrotron radiation will not
necessarily give rise to coherent emission (either enhanced isotropization
implied by quasilnear saturation of the instability).


title: Star Formation and Chemical Evolution of DLAs with Semi-Analytical Model

abstract:
  We have examined some basic properties of damped Ly$\alpha$ systems(DLAs) by
semi-analytic model. We assume that DLA hosts are disk galaxies whose mass
function is generated by Press-Schechter formulism at redshift 3. Star
formation and chemical evolution undergo in the disc. We select modelled DLAs
according to their observational criterion by Monte Carlo simulation using
random line of sights and disk inclinations. The DLA ages are set to be 1 to 3
Gyr. By best-fitting the predicted metallicity distribution to the observed
ones, we get the effective yield for DLAs about $0.25Z_{\odot}$. On the basis
of this constrain, we further compared our model predictions with observations
at redshift 3 in the following items: number density; gas content; HI frequency
distribution; star formation rate density; relationship between metallicity and
HI column density. We found that the predicted number density at redshift 3
agree well with the observed value, but the gas content $\Omega_{DLA}$ is about
3 times larger than observed since our model predicts more DLA systems with
higher column density. The frequency distribution at higher HI column density
is quite consistent with observation while some difference exists at lower HI
end. The predicted star formation rate density contributed by DLAs is
consistent with the most recent observations. Meanwhile, the connection between
DLAs and Lyman Break galaxies(LBGs) is discussed by comparing their UV
luminosity functions which shows that the DLAs host galaxies are much fainter
than LBGs. However, there is a discrepancy between model prediction and
observation in the correlation between metallicity and HI column density for
DLAs. Further investigations are needed for the star formation mode at high
redshift environments.


title:
Full-Polarization Observations of OH Masers in Massive Star-Forming
  Regions: I. Data

abstract:
  We present full-polarization VLBA maps of the ground-state, main-line, 2 Pi
3/2, J = 3/2 OH masers in 18 Galactic massive star-forming regions. This is the
first large polarization survey of interstellar hydroxyl masers at VLBI
resolution. A total of 184 Zeeman pairs are identified, and the corresponding
magnetic field strengths are indicated. We also present spectra of the NH3
emission or absorption in these star-forming regions. Analysis of these data
will be presented in a companion paper.


title:
Pulsation and evolutionary masses of classical Cepheids. I. Milky Way
  variables

abstract:
  We investigate a selected sample of Galactic classical Cepheids with
available distance and reddening estimates in the framework of the theoretical
scenario provided by pulsation models, computed with metal abundance Z=0.02,
helium content in the range of Y=0.25 to 0.31, and various choices of the
stellar mass and luminosity. After transforming the bolometric light curve of
the fundamental models into BVRIJK magnitudes, we derived analytical relations
connecting the pulsation period with the stellar mass, the mean
(intensity-averaged) absolute magnitude, and the color of the pulsators. These
relations are used together with the Cepheid observed absolute magnitudes in
order to determine the "pulsation" mass -M_p- of each individual variable. The
comparison with the "evolutionary" masses -M_(e,can)- given by canonical (no
convective core overshooting, no mass-loss) models of central He-burning
stellar structures reveals that the M_p/M_(e,can) ratio is correlated with the
Cepheid period, ranging from about 0.8 at logP=0.5 to about 1 at logP=1.5. We
discuss the effects of different input physics and/or assumptions on the
evolutionary computations, as well as of uncertainties in the adopted Cepheid
metal content, distance, and reddening. Eventually, we find that the
pulsational results can be interpreted in terms of mass-loss during or before
the Cepheid phase, whose amount increases as the Cepheid original mass
decreases. It vanishes around 13M_(sun) and increases up to about 20% at
4M_(sun).


title:
UHE Leptons and Neutrons feeding Precessing gamma Jet in GRBs - SGRs: A
  SGR 1806-20 link to EeV C.R.?

abstract:
  Soft Gamma Repeaters are widely believed to occur as isotropic Magnetar
explosion. We suggest on the contrary that they may be described by thin
collimated spinning and precessing Gamma Jets flashing and blazing along the
line of sight. The Jet (for SGRs) maybe powered by an accretion disk in binary
system and it reproduces huge outflow and oscillating blazing mode as the
observed ones in Giant Flare SGR 1806-20. The precessing and spinning blazing
nature reflects at smaller intensity the same behavior observed in brief GRBs
Jetted Supernova, as well as re-brightening and bumps in afterglows. The SGR
gamma beam maybe powered by Inverse Compton Scattering or by Synchrotron
Radiation of electron pair beam respectively at GeVs or PeVs energies. In the
latter case tens PeVs leptons (muons and later decaying PeVs electrons) might
be originated while EeV nucleons Jets (protons-neutrons) are in photo-pion
equilibrium with infrared photons surrounding the source. The neutron Jet might
survive and remain collimated. It maybe already detected as an EeV cosmic ray
anisotropy in present AGASA map pointing toward known (North Hemisphere) SGRs :
SGR 1900 +14 and SGR 1806-20. If the SGR-EeV connection is correct a parasite
traces of PeVs neutrino as well PeV-TeVs gamma rays might be found in present
or future data records, among the others C.R. array detectors, inside the
Amanda and Milagro volumes.


title: Unifying XRFs and GRBs with a Fisher-Shaped Universal Jet Model

abstract:
  We show analytically that GRB jets with an emissivity profile given by the
Fisher distribution, epsilon(theta) = A * e^(B cos(theta)), have the unique
property of producing equal numbers of bursts per logarithmic interval in Eiso,
and therefore in most burst properties. Since this broad distribution of burst
properties is a key feature found by HETE-2, a Fisher-shaped universal jet
model can explain many of the observed properties of XRFs, X-ray-rich GRBs, and
GRBs reasonably well, in contrast to a power-law universal model. For small
viewing angles, the Fisher distribution can be approximated by a Gaussian,
whose properties have been explored by Zhang et al. (2004). We also show that
the Fisher universal jet model produces a broad distribution in the inferred
radiated energy Egamma_inf, in contrast to the narrow distribution predicted by
the uniform variable opening-angle jet model Lamb, Donaghy & Graziani (2005).
Here we present Monte Carlo simulations of both a Fisher-shaped universal jet
model and a Fisher-shaped variable opening-angle jet model.


title: The Importance of Off-Axis Beaming in Jet Models

abstract:
  Gamma-Ray Bursts (GRBs) are widely thought to originate from collimated jets
of material moving at relativistic velocities. Emission from such a jet should
be visible even when viewed from outside the angle of collimation. Using Monte
Carlo population synthesis methods and including the effects of this off-axis
beaming, we can compare various GRB jet models against the global properties of
observed bursts. We explore whether or not the X-Ray Flashes (XRFs) seen by
HETE-2 and BeppoSAX can be explained as classical GRBs viewed off-axis, and
begin to address the more general question of the importance of off-axis
beaming in current burst samples.


title: Likelihood Analysis of GRB Evolution with Redshift

abstract:
  We present a likelihood approach to modeling multi-dimensional GRB
Epeak--fluence--redshift data that naturally incorporates instrument detection
thresholds. The treatment of instrument thresholds is essential for analyzing
evidence for GRB evolution. The method described here compares the data to a
uniform jet model, in which the jet parameters are allowed to vary with
redshift. Data from different experiments may be modeled jointly. In addition,
BATSE data (for which no redshift information is available) may be incorporated
by ascribing to each event a likelihood derived from the full model by
integrating the probability density over the unknown redshift. The loss of
redshift information is mitigated by the large number of available bursts. We
discuss the implementation of the method, and validation of it using simulated
data.


title: Size dependence of solar X-ray flare properties

abstract:
  Non-thermal and thermal parameters of 85 solar flares of GOES class B1 to M6
(background subtracted classes A1 to M6) have been compared to each other. The
hard X-ray flux has been measured by RHESSI and a spectral fitting provided
flux and spectral index of the non-thermal emission, as well as temperature and
emission measure of the thermal emission. The soft X-ray flux was taken from
GOES measurements. We find a linear correlation in a double logarithmic plot
between the non-thermal flux and the spectral index. The higher the
acceleration rate of a flare, the harder the non-thermal electron distribution.
The relation is similar to the one found by a comparison of the same parameters
from several sub-peaks of a single flare. Thus small flares behave like small
subpeaks of large flares. Thermal flare properties such as temperature,
emission measure and the soft X-ray flux also correlate with peak non-thermal
flux. A large non-thermal peak flux entails an enhancement in both thermal
parameters. The relation between spectral index and the non-thermal flux is an
intrinsic feature of the particle acceleration process, depending on flare
size. This property affects the reported frequency distribution of flare
energies.


title:
HST and UKIRT Observations of the Center of the Trifid Nebula: Evidence
  for the Photoevaporation of a Proplyd and a Protostellar Condensation

abstract:
  The Trifid nebula (M20) is a well-known prominent optical HII region
trisected by bands of obscuring dust lanes and excited by an O7.5 star HD
164492A. Previous near-IR, mid-IR and radio continuum observations of the
cluster of stars at the center of the Trifid nebula indicated circumstellar
disks associated with hot stars with envelopes that are photoionized externally
by the UV radiation from the hot central star, HD 164492A. Using WFPC2 of the
HST, we present evidence of a resolved proplyd in H$\alpha$ and [SII] line
emission from a stellar source emitting cool dust emission. Using UKIRT, an
infrared observation of the stellar source with a proplyd indicates a late F --
mid G spectral type. We also note a remarkable complex of filamentary and
sheet-like structures which appear to arise from the edge of a protostellar
condensation. These observations are consistent with a picture in which the
bright massive star HD 164492A is responsible for the photoevaporation of
protoplanetary disks of other less-massive members of the cluster as well as
the closest protostellar condensation facing the central cluster. Using the
evidence for a proplyd, we argue that the massive and intermediate mass members
of the cluster, HD 164492C (B6 star) and HD 164492 (Herbig Be star) have disks
associated with them.


title: Jet Models of X-Ray Flashes

abstract:
  One third of all HETE-2--localized bursts are X-Ray Flashes (XRFs), a class
of events first identified by Heise in which the fluence in the 2-30 keV energy
band exceeds that in the 30-400 keV energy band. We summarize recent HETE-2 and
other results on the properties of XRFs. These results show that the properties
of XRFs, X-ray-rich gamma-ray bursts (GRBs), and GRBs form a continuum, and
thus provide evidence that all three kinds of bursts are closely related
phenomena. As the most extreme burst population, XRFs provide severe
constraints on burst models and unique insights into the structure of GRB jets,
the GRB rate, and the nature of Type Ib/Ic supernovae. We briefly mention a
number of the physical models that have been proposed to explain XRFs. We then
consider two fundamentally different classes of phenomenological jet models:
universal jet models, in which it is posited that all GRBs jets are identical
and that differences in the observed properties of the bursts are due entirely
to differences in the viewing angle; and variable-opening angle jet models, in
which it is posited that GRB jets have a distribution of jet opening angles and
that differences in the observed properties of the bursts are due to
differences in the emissivity and spectra of jets having different opening
angles. We consider three shapes for the emissivity as a function of the
viewing angle theta_v from the axis of the jet: power-law, top hat (or
uniform), and Gaussian (or Fisher). We then discuss the effect of relativistic
beaming on each of these models. We show that observations can distinguish
between these various models.


title:
Second-order gravitational effects of local inhomogeneities on CMB
  anisotropies in nonzero-Lambda flat cosmological models

abstract:
  Nonlinear gravitational effects of large-scale inhomogeneities on Cosmic
Microwave Background (CMB) anisotropies are studied. based on the relativistic
second-order theory of perturbations in nonzero-Lambda flat cosmological
models, which has been analytically derived by the present author, and on the
second-order formula of CMB anisotropies derived by Mollerach and Matarrese. In
this paper we derive the components of the CMB anisotropy power spectra in the
range of l = 1 -22 which are caused by asymmetric local inhomogeneities on
scales of 300 Mpc. Using our results it is found that there is a possibility to
explain the small north-south asymmetry of CMB anisotropies which has recently
been observed.


title:
Precision of Inflaton Potential Reconstruction from CMB Using the
  General Slow-Roll Approximation

abstract:
  Through a principal component analysis, we study how accurately CMB
observables can constrain inflaton potentials in a model independent manner. We
apply the general slow-roll approximation in our analysis where we allow, in
contrast to the standard slow-roll approximation, the possibility of variations
in $V''(\phi)$ and take into account the fact that horizon crossing is not an
instantaneous event. Our analysis provides a set of modes to be used in fitting
observables. We find that of order five of these modes will be constrained by
future observations, so a fully general data analysis package could use the
amplitudes of just a handful of modes as free parameters and retain all
relevant information in the data.


title:
Phenomenological Analogies in TeV Blazars and Black Hole X-ray Binaries
  in low state

abstract:
  Blazars are well known for the violent variability from the radio to
gamma-ray wavelengths. In this paper, we present a brief summary of the X-ray
variability recently obtained for TeV blazars. We also point out the probable
similarities of the X-ray variability characteristics between blazars and
microblazars. Such phenomenological analogies could be interpreted and unified
with the synchrotron X-ray emissions from the jets of the two classes of
objects that differ in black hole mass by factors of $\ga 10^7$. The
phenomenological analogies in blazars and microblazars (both are jet-dominated)
might be parallel to those in black hole X-ray binaries in high/soft state and
Seyfert galaxies (both are disk-dominated).


title:
XMM-Newton View of PKS 2155-304: Characterizing the X-ray Variability
  Properties with EPIC-PN

abstract:
  Starting from XMM-Newton EPIC-PN data, we present the X-ray variability
characteristics of PKS 2155-304 using a simple analysis of the excess variance,
\xs, and of the fractional rms variability amplitude, fvar. The scatter in \xs\
and \fvar, calculated using 500 s long segments of the light curves, is smaller
than the scatter expected for red noise variability. This alone does not imply
that the underlying process responsible for the variability of the source is
stationary, since the real changes of the individual variance estimates are
possibly smaller than the large scatters expected for a red noise process. In
fact the averaged \xs and \fvar, reducing the fluctuations of the individual
variances, chang e with time, indicating non-stationary variability. Moreover,
both the averaged \sqxs (absolute rms variability amplitude) and \fvar show
linear correlation with source flux but in an opposite sense: \sqxs correlates
with flux, but \fvar anti-correlates with flux. These correlations suggest that
the variability process of the source is strongly non-stationary as random
scatters of variances should not yield any correlation. \fvar spectra were
constructed to compare variability amplitudes in different energy bands. We
found that the fractional rms variability amplitude of the source, when
significant variability is observed, increases logarithmically with the photon
energy, indicating significant spectral variability. The point-to-point
variability amplitude may also track this trend, suggesting that the slopes of
the power spectral density of the source are energy-independent. Using the
normalized excess variance the black hole mass of \pks was estimated to be
about $1.45 \times 10^8 M_{\bigodot}$. This is compared and contrasted with the
estimates derived from measurements of the host galaxies.


title:
Molecular gas and continuum emission in 3C48: Evidence for two merger
  nuclei?

abstract:
  We present new interferometer observations of the CO(1-0) line and mm
continuum emission from 3C48 - one of the nearest examples of a merger
activating a quasar. Our new CO data show that most of the CO is not in a disk
around the quasar 3C48, but rather in a second nucleus associated with the
source 3C48A ~1" to the north-east, recently studied in the near-IR by Zuther
et al. (2004). This main CO source has a strong velocity gradient (140km/s over
about 1"). Our new data also show a second, weaker CO source at the QSO itself.
At 1.2mm, the continuum emission is elongated in the direction of the radio jet
and towards 3C48A. We model the 1.2mm continuum with three different sources in
3C48 - the 3C48 QSO, the 3C48 jet, and the second nucleus 3C48A. We suggest
that the unusually bright and extended nature of the jet may be due to its
interaction with the second merger nucleus 3C48A.


title:
Age spreads in star forming regions: The lithium test in the Orion
  Nebula Cluster

abstract:
  We present the initial results of a study of the surface lithium abundance in
a sample of low-mass members (M~0.4-1.0 Msun) of the Orion Nebula Cluster (ONC)
that provide an independent clock to estimate stellar ages. We report discovery
of significant depletion of lithium in four stars with estimated mass of ~0.4
Msun and age ~10Myr. Comparison with the predictions of numerical and
analytical models shows excellent agreement between the isochronal age and
lithium depletion time scale for two objects, the first case in lithium-poor
pre-main sequence stars. Our results bear on the issue of the real age spread
in the ONC and hence on the overall duration of the star formation process,
indicating that the stellar population did not came into existence in a single,
rapid burst.


title: Spherical Collapse Model And Dark Energy(I)

abstract:
  In existing literatures about the top-hat spherical collapse model of galaxy
clusters formation in cosmology containing dark energies, dark energies are
usually assumed not to cluster on this scale. But all these literatures ignored
the current describing the flowing of dark energies outside the clusters which
should exist under this assumption, so the conclusions of these literatures are
worth further explorations. In this paper we study this model in QCDM or
Phantom-CDM cosmologies(flat) by assuming that dark energies will cluster
synchronously with ordinary matters on the scale of galaxy clusters so the dark
energy current flowing outside the clusters does not exist at all and find that
in this case, the key parameters of the model exhibit rather non-trivial and
remarkable dependence on the equation of state coefficients of dark energies.
We then apply the results in
  Press-Scheter theory and calculate the number density of galaxy clusters and
its evolutions. We find that this two quantities are both affected
exponentially by the equation of state coefficients of dark energies. We leave
the study of this model with the assumption that dark energies do not cluster
on the scale of galaxy clusters at all as the topic of another paper where
similar conclusions will be obtained also.


title: Spherical Collapse Model And Dark Energy(II)

abstract:
  This is a second paper of a series of two. In this paper, we directly correct
the problem pointed out in the first paper of this series, dark energy does not
cluster on the scale of galaxy clusters, but the current describing the flowing
of dark energies outside the clusters is ignored in almost all the previous
papers. We set up and solve a first order differential equation which describes
the evolution of the clusters in a back ground universe containing dark
energies.
  From the solution we extract the key parameters of the model and find them
depending on the equation of state coefficients of dark energies rather
non-trivially. We then apply the results in Press-Scheter theory and calculate
the number density of galaxy clusters and its evolutions, we find the
observable quantities are strongly affected by the equation of state
coefficients of dark energies.


title:
Mapping the Physical Properties of Cosmic Hot Gas with Hyper-spectral
  Imaging

abstract:
  A novel inversion technique is proposed to compute parametric maps showing
the temperature, density and chemical composition of cosmic hot gas from X-ray
hyper-spectral images. The parameters are recovered by constructing a unique
non-linear mapping derived by combining a physics-based modelling of the X-ray
spectrum with the selection of optimal bandpass filters. Preliminary results
and analysis are presented.


title:
Extracting energy from black holes: "long" and "short" GRBs and their
  astrophysical settings

abstract:
  The introduction of the three interpretational paradigms for Gamma-Ray Bursts
(GRBs) and recent progress in understanding the X- and gamma ray luminosity in
the afterglow allow us to make assessments about the astrophysical settings of
GRBs. In particular, we evidence the distinct possibility that some GRBs occur
in a binary system. This subclass of GRBs manifests itself in a "tryptich": one
component formed by the collapse of a massive star to a black hole, which
originates the GRB; a second component by a supernova and a third one by a
young neutron star born in the supernova event. Similarly, the understanding of
the physics of quantum relativistic processes during the gravitational collapse
makes possible precise predictions about the structure of short GRBs.


title: Is There a Microlensing Puzzle?

abstract:
  Using neural networks, Belokurov, Evans & Le Du (2003, 2004) showed that 7
out of the 29 microlensing candidates towards the Large Magellanic Cloud (LMC)
of the MACHO collaboration are consistent with blended microlensing and added
Gaussian noise. They then estimated the microlensing optical depth to the LMC
to be between 0.3 x 10^{-7} and 0.5 x 10^{-7}, lower by about a factor of two
than that found by the MACHO collaboration. There has been a recent independent
claim of a low optical depth to the LMC by the EROS collaboration, who find
0.15 x 10^{-7} from 3 candidates (Tisserand et al 2006). Griest & Thomas (2005)
have contested our calculations. Unfortunately, their paper contains a number
of scientific misrepresentations of our work. We stand by our application of
neural networks to microlensing searches and believe it to be a technique of
great promise. Rather, the main cause of the disparity between Griest & Thomas
and Belokurov et al. lies in the very different datasets through which these
investigators look for microlensing events. We don't exclude the possibility
that some of our non-microlensing designations may change with access to clean
data. Whilst not everything is understood about the microlensing datasets
towards the LMC, the latest downward revisions of the optical depth means that
Griest & Thomas' microlensing puzzle is a roughly 1 sigma effect. Efficiency
calculations can correct for the effects of false negatives, but they cannot
correct for the effects of false positives (variable stars that are mistaken
for microlensing). Therefore, the best strategy in a microlensing experiment is
to eschew a decision boundary altogether. Rather, each lightcurve should be
assigned a probability and the microlensing rate calculated by summing over the
probabilities of all such lightcurves.


title: Chemical differentiation along the CepA-East outflows

abstract:
  We present the results of a multiline survey at mm-wavelengths of the Cepheus
A star forming region. Four main flows have been identified: three pointing in
the SW, NE, and SE directions and accelerating high density CS clumps. The
fourth outflow, revealed by high-sensitivity HDO observations, is pointing
towards South and is associated with conditions particularly favourable to a
chemical enrichment. The analysis of the line profiles shows that the SiO
molecule dominates at the highest velocities and at the highest excitation
conditions, confirming its close association with shocks. H2S, SO2, and SO
preferentially trace more quiescent regions than SiO, and in particular a lack
of bright H2S emission at the highest velocities is found. OCS and H2CS emit at
quite high velocities, where the abundances of three shock tracers like SiO,
CH3OH, and HDO are higher. These results may indicate that H2S is not the only
major sulphur carrier in the grain mantles, and that OCS and H2CS may probably
play an important role on the grains; or that alternatively they rapidly form
once the mantle is evaporated after the passage of a shock. Finally, the
outflow peak emission has been compared with recent time-dependent sulphur
chemistry models: the results indicate that, if associated with accurate
measurements of the physical conditions, the CH3OH/H2CS column density ratio
can be used as an effective chemical clock to date the age of shocked gas.


title:
Modeling the 3--D Secular Planetary Three-Body Problem. Discussion on
  the outer ${\upsilon}$ Andromedae Planetary System

abstract:
  The three-dimensional secular behavior of a system composed of a central star
and two massive planets is modeled semi-analytically in the frame of the
general three-body problem. The main dynamical features of the system are
presented in geometrical pictures allowing us to investigate a large domain of
the phase space of this problem without time-expensive numerical integrations
of the equations of motion and without any restriction on the magnitude of the
planetary eccentricities, inclinations and mutual distance. Several regimes of
motion of the system are observed. With respect to the secular angle
$\Delta\varpi$, possible motions are circulations, oscillations (around 0 and
$180^\circ$), and high eccentricity/inclination librations in secular
resonances. With respect to the arguments of pericenter, $\omega_1$ and
$\omega_2$, possible motions are direct circulation and high-inclination
libration around $\pm 90^\circ$ in the Lidov-Kozai resonance. The regions of
transition between domains of different regimes of motion are characterized by
chaotic behavior.
  We apply the analysis to the case of the two outer planets of the $\upsilon$
Andromedae system, observed edge-on. The topology of the 3--D phase space of
this system is investigated in detail by means of surfaces of section, periodic
orbits and dynamical spectra, mapping techniques and numerical simulations. We
obtain the general structure of the phase space, and the boundaries of the
spatial secular stability. We find that this system is secularly stable in a
large domain of eccentricities and inclinations.


title:
Unification in the low radio luminosity regime; evidence from optical
  line emission

abstract:
  We address the question of whether or not the properties of all
low-luminosity flat spectrum radio sources, not just the obvious BL Lac
objects, are consistent with them being the relativistically beamed
counterparts of the low radio luminosity radio galaxies (the Fanaroff-Riley
type 1 - FRI). We compare the emission-line luminosities of a well studied
sample of core-dominated radio sources with a matched sample of FR I radio
galaxies. The emission lines in the core-dominated objects are on average
significantly more luminous than those in the comparison sample, inconsistent
with the simplest unified models in which there is no orientation dependence of
the line emission. However, the results are equally consistent with a scenario
in which, for the majority of objects, beaming has minimal effect on the
observed core luminosities of a large fraction of the FRI population and that
intrinsically stronger cores simply give rise to stronger emission lines. We
conclude that FRI unification is much more complex than usually portrayed, and
models combining beaming with an intrinsic relationship between core and
emission line strengths need to be explored.


title:
Modeling the Physical Structure of the Low Density Pre-protostellar Core
  Lynds 1498

abstract:
  Lynds 1498 is a pre-protostellar core (PPC) and was one of the initial
objects toward which molecular depletion and differentiation was detected.
Despite the considerable scrutiny of L1498, there has not been a extensive
study of the density and temperature structure as derived from radiative
transfer modeling of dust continuum observations. We present deep SCUBA
observations of L1498 at 850 and 450 micron, high resolution BEARS maps of the
N2H+ 1-0 transition, CSO observations of the N2H+ 3-2 transition, and GBT
observations of the C3S 4-3 transition. We also present a comparison of derived
properties between L1498 and nearby PPCs that have been observed at
far-infrared and submillimeter wavelengths. We present a more realistic
treatment of PPC heating which varies the strength of the ISRF, Sisrf, and
includes attenuation of the ISRF due to dust grains at the outer radius of the
core, Av. The best-fitted model consists of a Bonner-Ebert sphere with a
central density of 1 - 3 x 10^4 cm-3, R_o ~ 0.29 pc, 0.5 <= Sisrf <= 1, Av ~ 1
mag, and a nearly isothermal temperature profile of ~ 10.5 K for OH8 opacities.
C3S emission shows a central depletion hole while N2H+ emission is centrally
peaked. The observed depletions of C3S and H2CO, the modest N2H+ abundance, and
a central density that is an order of magnitude lower than other modeled PPCs
suggests that L1498 may be a forming PPC. Our derived temperature and density
profile will improve modeling of molecular line observations that will
explicate the core's kinematical and chemical state. (abridged)


title:
Fully Threaded Transport Engine: New Method for Multi-Scale Radiative
  Transfer

abstract:
  A new, very fast method for 3D radiative transfer on fully threaded grids
with arbitrarily high angular resolution is presented. The method uses
completely cell-based discretization, and is ideally suited for problems with
diffuse background radiation, often encountered in cosmological and star
formation models. We find that for accurate statistical study of intergalactic
Ly-alpha absorption lines one needs of order of few hundred angular
discretization elements even for models without radiative feedback from star
forming galaxies.


title: Measuring the Primordial Deuterium Abundance During the Cosmic Dark Ages

abstract:
  We discuss how measurements of fluctuations in the absorption of cosmic
microwave background (CMB) photons by neutral gas during the cosmic dark ages,
at redshifts z ~ 7--200, could reveal the primordial deuterium abundance of the
Universe. The strength of the cross-correlation of brightness-temperature
fluctuations due to resonant absorption of CMB photons in the 21-cm line of
neutral hydrogen with those due to resonant absorption of CMB photons in the
92-cm line of neutral deuterium is proportional to the fossil deuterium to
hydrogen ratio [D/H] fixed during big bang nucleosynthesis (BBN). Although
technically challenging, this measurement could provide the cleanest possible
determination of [D/H], free from contamination by structure formation
processes at lower redshifts, and has the potential to improve BBN constraints
to the baryon density of the Universe \Omega_{b} h^2. We also present our
results for the thermal spin-change cross-section for deuterium-hydrogen
scattering, which may be useful in a more general context than we describe
here.


title:
First and second-type self-similar solutions of implosions and
  explosions containing ultra-relativistic shocks

abstract:
  We derive self similar solutions for ultra-relativistic shock waves
propagating into cold material of powerlaw density profile in radius rho ~
r^-k. We treat both implosions and explosions in three geometries: planar,
cylindrical and spherical. For spherical explosions these are the first type
solutions of Blandford and McKee for k<4 and the second type solutions found by
Best and Sari for k>5-sqrt(3/4). In addition we find new, hollow (with
evacuated interior), first type solutions that may be applicable for 4<k<17/4.
This ``sequence'' with increasing k of first type solutions, hollow first type
solutions, and then second type solutions is reminiscent of the
non-relativistic sequence. However, while in the non relativistic case there is
a range of k which corresponds to a ``gap'' - a range in $k$ with neither first
nor second type solutions which separates the hollow first type solutions and
the second type solutions, here there is an ``overlap'': a range of k for which
current considerations allow for both hollow first and second type solutions.
Further understanding is needed to determine which of the two solutions apply
in this overlap regime. We provide similar exploration for the other geometries
and for imploding configurations. Interestingly, we find a gap for imploding
spherical shocks and exploding planar shocks and an overlap for imploding
planar solutions. Cylindrical configurations have no hollow solutions and
exhibit direct transition from first type to second type solutions, without a
gap or an overlap region.


title:
Effects of Rotation and Relativistic Charge Flow on Pulsar
  Magnetospheric Structure

abstract:
  We propose an analytical 3-D model of the open field-line region of a neutron
star (NS) magnetosphere. We construct an explicit analytic solution for
arbitrary obliquity (angle between the rotation and magnetic axes)
incorporating the effects of magnetospheric rotation, relativistic flow of
charges (e.g. primary electron beam) along the open field lines, and E X B
drift of these charges. Our solution employs the space-charge-limited
longitudinal current calculated in the electrodynamic model of Muslimov &
Tsygan (1992) and is valid up to very high altitudes nearly approaching the
light cylinder. We assume that in the innermost magnetosphere, the NS magnetic
field can be well represented by a static magnetic dipole configuration. At
high altitudes the open magnetic field lines significantly deviate from those
of a static dipole and tend to focus into a cylindrical bundle, swept back in
the direction opposite to the rotation, and also bent towards the rotational
equator. We briefly discuss some implications of our study to spin-powered
pulsars.


title:
Self-similar solutions for relativistic shocks emerging from stars with
  polytropic envelopes

abstract:
  We consider a strong ultrarelativistic shock moving through a star whose
envelope has a polytrope-like density profile. When the shock is close to the
star's outer boundary, its behavior follows the self-similar solution given by
Sari (2005) for implosions in planar geometry. Here we outline this solution
and find the asymptotic solution as the shock reaches the star's edge. We then
show that the motion after the shock breaks out of the star is described by a
self-similar solution remarkably like the solution for the motion inside the
star. In particular, the characteristic Lorentz factor, pressure, and density
vary with time according to the same power laws both before and after the shock
breaks out of the star. After emergence from the star, however, the
self-similar solution's characteristic position corresponds to a point behind
the leading edge of the flow rather than at the shock front, and the relevant
range of values for the similarity variable changes. Our numerical integrations
agree well with the analytic results both before and after the shock reaches
the star's edge.


title:
A General Theory of Turbulence-Regulated Star Formation, From Spirals to
  ULIRGs

abstract:
  We derive an analytic prediction for the star formation rate in environments
ranging from normal galactic disks to starbursts and ULIRGs in terms of the
observables of those systems. Our calculation is based on three premises: (1)
star formation occurs in virialized molecular clouds that are supersonically
turbulent; (2) the density distribution within these clouds is lognormal, as
expected for supersonic isothermal turbulence; (3) stars form in any sub-region
of a cloud that is so overdense that its gravitational potential energy exceeds
the energy in turbulent motions. We show that a theory based on this model is
consistent with simulations and with the observed star formation rate in the
Milky Way. We use our theory to derive the Kennicutt-Schmidt Law from first
principles, and make other predictions that can be tested by future
observations. We also provide an algorithm for estimating the star formation
rate that is suitable for inclusion in numerical simulations.


title: Evidence for an X-Ray Jet in DG Tau A?

abstract:
  We present evidence for an X-ray jet in the T Tau star DG Tau A based on
Chandra ACIS data. DG Tau A, a jet-driving classical T Tau star with a flat
infrared spectrum, reveals an unusual X-ray spectrum that requires two thermal
components with different intervening absorption column densities. The softer
component shows a low temperature of T \approx 2.9 MK, and its absorption is
compatible with the stellar optical extinction (hydrogen column density N_H
\approx 5x10^21 cm^-2). In contrast, the harder component reveals a temperature
(22 MK) characteristic for active T Tau stars but its emission is more strongly
absorbed (N_H \approx 2.8x10^22 cm^-2). Furthermore, the high-resolution ACIS-S
image reveals a weak excess of soft (0.5-2 keV) counts at distances of 2-4"
from the star precisely along the optical jet, with a suggestive concentration
at 4" where a bow-shock-like structure has previously been identified in
optical line observations. The energy distribution of these photons is similar
to those of the stellar soft component. We interpret the soft spectral
component as originating from shocks at the base of the jet, with shock heating
continuing out to a distance of at least 500 AU along the jet, whereas the hard
component is most likely coronal/magnetospheric as in other young stellar
systems.


title:
Reconstructing the Triaxial Shapes of Dark Matter Halos from the
  Anisotropic Spatial Distributions of their Substructures in the Concordance
  Cosmology

abstract:
  We develop an algorithm to reconstruct the triaxial shapes of dark matter
halos from the anisotropic spatial distributions of their substructures for the
concordance background cosmology. First, we construct an analytic model for the
anisotropic spatial distribution of dark halo substructures under the
assumption that the tidal field with non-zero trace in the triaxial mass
distribution of the host halos generates the substructure bulk motions toward
the major principal axes of the hosts. Our analytic model implies that the
degree of anisotropy depends sensitively on the triaxiality of the host halos
as well as the correlation between the substructure locations and the tidal
shear field. Second, we set the axis ratios of the triaxial host halos as free
parameters in the analytic model, fit the model to the numerical results from
high-resolution N-body simulation of the concordance cosmology, and reconstruct
the two axis-ratios of the host halos from the best-fit values of the free
parameters. The comparison of the reconstructed axis ratios with the numerical
results reveals a good agreement. Finally, we conclude that our analytic model
may provide a physical understanding of the anisotropic spatial distribution of
dark halo substructures and a new way to reconstruct in principle the triaxial
shapes of dark matter halos from the observables.


title: Multi-epoch VERA Observations of H2O masers in OH 43.8-0.1

abstract:
  We report on the multi-epoch observations of H2O maser emission in star
forming region OH 43.8-0.1 carried out with VLBI Exploration of Radio
Astrometry (VERA). The large-scale maser distributions obtained by single-beam
VLBI mapping reveal new maser spots scattered in area of 0.7 x 1.0 arcsec, in
addition to a `shell-like' structure with a scale of 0.3 x 0.5 arcsec which was
previously mapped by Downes et al.(1979). Proper motions are also obtained for
43 spots based on 5-epoch monitoring with a time span of 281 days. The
distributions of proper motions show a systematic outflow in the north-south
direction with an expansion velocity of ~8 km/s, and overall distributions of
maser spots as well as proper motions are better represented by a bipolar flow
plus a central maser cluster with a complex structure, rather than a shell with
a uniform expansion such as those found in Cep A R5 and W75N VLA2. The distance
to OH 43.8-0.1 is also estimated based on the statistical parallax, yielding D
= 2.8 +/- 0.5 kpc. This distance is consistent with a near kinematic distance
and rules out a far kinematics distance (~9 kpc), and the LSR velocity of OH
43.8-0.1 combined with the distance provides a constraint on the flatness of
the galactic rotation curve, that there is no systematic difference in rotation
speeds at the Sun and at the position of OH 43.8-0.1, which is located at the
galacto-centric radius of ~6.3 kpc.


title:
A cosmological "probability event horizon" and its observational
  implications

abstract:
  Suppose an astronomer is equipped with a device capable of detecting
emissions -- whether they be electromagnetic, gravitational, or neutrino --
from transient sources distributed throughout the cosmos. Because of source
rate density evolution and variation of cosmological volume elements, the
sources first detected when the machine is switched on are likely to be ones in
the high-redshift universe; as observation time increases, rarer, more local,
events will be found. We characterize the observer's evolving record of events
in terms of a "probability event horizon", converging on the observer from
great distances at enormous speed, and illustrate it by simulating neutron star
birth events distributed throughout the cosmos. As an initial application of
the concept, we determine the approach of this horizon for gamma-ray bursts
(GRBs) by fitting to redshift data. The event rates required to fit the model
are consistent with the proposed link between core-collapse supernovae and a
largely undetected population of faint GRBs.


title:
Signature of Galactic Outflows as Absorption-Free Gaps in the Ly-alpha
  Forest

abstract:
  Powerful outflows from star-forming galaxies are expected to push away the
neutral intergalactic medium (IGM) around those galaxies, and produce
absorption-free gaps in the Ly-alpha forest. We analyze the abundance of gaps
of various sizes in three high resolution spectra of quasars at z ~ 3 - 3.5.
The gap statistics agrees well with a model in which galactic halos above a
minimum mass scale of M_min ~ 10^10 M_sun produce bubbles with a characteristic
radius of R_b ~ 0.48 Mpc/h. Both numbers are consistent with naive theoretical
expectations, where the minimum galaxy mass reflects the threshold for infall
of gas out of a photo-ionized IGM. The observed gaps are typically bounded by
deep absorption features as expected from the accumulation of swept-up gas on
the bubble walls.


title: Scaling variability from stellar to supermassive black holes

abstract:
  We investigate the correspondence between the variability seen in the stellar
and supermassive black holes. Galactic Black Hole (GBH) power density spectra
(PDS) are generally complex, and dependent on spectral state. In the low/hard
state the high-frequency rollover in the PDS moves in a way which is not simply
related to luminosity. Hence this feature can only be used as an approximate
indicator rather than as an accurate tracer of black hole mass in AGN. The
X-ray spectrum in the high/soft state is dominated by the disc in GBH, which is
rather stable. We show that the PDS of the Comptonized tail in GBH can be much
more variable, and that it is this which should be compared to AGN due to their
much lower disc temperature. This bandpass effect removes a problem in
interpreting the (often highly variable) Narrow Line Seyfert 1 (NLS1) galaxies
as the counterparts of the high mass accretion rate GBH. Additionally, we
speculate that some NLS1 (e.g. Akn 564) are counterparts of the very high
state. The Comptonized tail in this state is also highly variable, but with PDS
which can be roughly described as band-limited noise. This shape is similar to
that seen in the low/hard state, so merely seeing such band-limited noise in
the power spectrum of an AGN does not necessarily imply low luminosity. We also
stress that Cyg X-1, often used for comparison with AGN, is not a typical black
hole system due to its persistent nature. In particular, the shape of its power
spectrum in the high/soft state is markedly different from that of other
(transient) GBH systems in this state. The fact that the NLS1s NGC 4051 and
MCG-6-30-15 do appear to show a power spectrum similar to that of the high/soft
state of Cyg X-1 may lend observational support to theoretical speculation that
the Hydrogen ionization disc instability does not operate in AGN.


title: Multi-periodic oscillations of alpha Hya

abstract:
  We report the detection of multi-periodic oscillations of the cool evolved
star alpha Hya (HD 81797, K3II-III). Two-hundred and forty-three
high-resolution spectra (R=48,000) of this star have been obtained in March and
April 2005 with FEROS at the 2.2 m-MPG/ESO telescope in La Silla Observatory,
Chile. We observed oscillations in the stellar radial velocity and the
asymmetry of the spectral line profile. We detected oscillation frequencies of
the stellar radial velocity in two frequency regions, nu= 2-30 muHz and nu=
50-120 muHz. The corresponding periods are P= 0.6-5.6 days and P= 2.3-5.5
hours, respectively. In addition to these oscillations we also observed a trend
in the radial velocity which shows evidence for a long-term variability.
Furthermore, our measurements show a correlation between the variation in the
radial velocity and the asymmetry of the spectral line profile, as measured in
the bisector velocity spans. The line bisectors also show oscillations in the
same frequency regions as those of the radial velocity. We identified 13
oscillation frequencies in the bisector variation with equidistant separations
of 8.09 +- 0.32 muHz in the lower frequency region and 7.69 +- 0.47 muHz in the
higher frequency region. The source of the short-term oscillations of alpha Hya
is obviously due to non-radial stellar pulsations. These oscillations may have
a similar origin like oscillations in solar-like stars. The detection of the
multi-periodic oscillations in alpha-Hya makes this star to be an amenable
target for asteroseismology, in particular, as it is a star in the red giant
branch.


title: Fractal Approach to Large-Scale Galaxy Distribution

abstract:
  We present a review of the history and the present state of the fractal
approach to the large-scale distribution of galaxies. Angular correlation
function was used as a general instrument for the structure analysis. It was
realized later that a normalization condition for the reduced correlation
function estimator results in distorted values for both R_{hom} and fractal
dimension D. Moreover, according to a theorem on projections of fractals,
galaxy angular catalogues can not be used for detecting a structure with the
fractal dimension D>2. For this 3-d maps are required, and indeed modern
extensive redshift-based 3-d maps have revealed the ``hidden'' fractal
dimension of about 2, and have confirmed superclustering at scales even up to
500 Mpc (e.g. the Sloan Great Wall). On scales, where the fractal analysis is
possible in completely embedded spheres, a power--law density field has been
found. The fractal dimension D =2.2 +- 0.2 was directly obtained from 3-d maps
and R_{hom} has expanded from 10 Mpc to scales approaching 100 Mpc. In
concordance with the 3-d map results, modern all sky galaxy counts in the
interval 10^m - 15^m give a 0.44m-law which corresponds to D=2.2 within a
radius of 100h^{-1}_{100} Mpc. We emphasize that the fractal mass--radius law
of galaxy clustering has become a key phenomenon in observational cosmology.


title: The counterparts of Local Group dwarf spheroidals in nearby clusters

abstract:
  In this contribution, we report on the discovery of dwarf spheroidals (dSphs)
in the core of the Fornax cluster. Their photometric properties -- like
magnitude, colour, surface brightness -- are very similar to those of Local
Group dSphs. However, at a given total magnitude, dSphs in Fornax seem to be
more extended than their Local Group counterparts. The membership of several
dwarf galaxy candidates in Fornax has been confirmed by surface brightness
fluctuation measurements on deep wide-field images taken with the Magellan
telescope. The analysis of these images also confirms the flat faint end slope
of the luminosity function for dSphs in Fornax which contradicts the expected
large number of small dark matter halos connected to dwarf galaxies in
LambdaCDM theory. Dwarf spheroidals have also been detected in the Hydra I and
Centaurus cluster. A preliminary analysis of their photometric properties shows
that they obey similar scaling relations as their counterparts in Fornax and
the Local Group.


title: UCDs in Fornax and Abell 1689

abstract:
  We review some properties of ultracompact dwarf galaxies (UCDs) in Fornax and
of their brighter counterparts in Abell 1689, among which are two M32 twins,
and discuss various possible UCD formation scenarios. We note that it is
indispensable to carefully take into account the bright end of the globular
cluster luminosity function when estimating the number density of UCDs. It is
suggested that the search for more luminous UCDs in dense and rich galaxy
clusters is the best way towards establishing UCDs as a new class of galaxies.


title: Inflationary Solutions in Nonminimally Coupled Scalar Field Theory

abstract:
  We study analytically and numerically the inflationary solutions for various
type scalar potentials in the nonminimally coupled scalar field theory. The
Hamilton-Jacobi equation is used to deal with nonlinear evolutions of
inhomogeneous spacetimes and the long-wavelength approximation is employed. The
constraints that lead to a sufficient inflation are found for the nonminimal
coupling constant and initial conditions of the scalar field for inflation
potentials. In particular, we numerically find an inflationary solution in the
new inflation model of a nonminimal scalar field.


title:
VLTI observations of IRS~3: The brightest compact MIR source at the
  Galactic Centre

abstract:
  The dust enshrouded star IRS~3 in the central light year of our galaxy was
partially resolved in a recent VLTI experiment. The presented observation is
the first step in investigating both IRS~3 in particular and the stellar
population of the Galactic Centre in general with the VLTI at highest angular
resolution. We will outline which scientific issues can be addressed by a
complete MIDI dataset on IRS~3 in the mid infrared.


title:
The initial conditions of isolated star formation - VI. SCUBA mapping of
  prestellar cores

abstract:
  Observations have been carried out with SCUBA at the JCMT of 52 molecular
cloud cores that do not contain any sign of protostellar activity. These are
all therefore candidate prestellar cores, which are believed to represent the
stage of star formation that precedes the formation of a protostar. 29 of the
52 cores were detected at 850 microns at varying levels of signal-to-noise
ratio greater than 3 sigma at peak. The detected cores were split into 'bright'
cores and `intermediate' cores, depending on their peak flux density at 850
microns. Cores with peak 850 microns flux densities greater than 170 mJy/beam
were designated 'bright' (13 cores), while those flux densities below this
value were designated 'intermediate' (16 cores). This dividing line corresponds
to A_v~50 under typical assumptions. The data are combined with our previously
published ISO data, and the physical parameters of the cores, such as density
and temperature, are calculated. Detailed fitting of the bright core radial
profiles shows that they are not critical Bonnor-Ebert spheres, in agreement
with previous findings. However, we find that intermediate cores, such as B68
(which has previously been claimed to be a Bonnor-Ebert sphere), may in fact be
consistent with the Bonnor-Ebert criterion, suggesting perhaps that cores pass
through such a phase during their evolution. We make rough estimates of core
lifetimes based on the statistics of detections and find that the lifetime of a
prestellar core is roughly ~3x10^5 years, while that of a bright core is
\~1.5x10^5 years. Comparisons with some magnetic and turbulence regulated
collapse models show that no model can match all of the data. Models that are
tuned to fit the total prestellar core lifetime, do not predict the relative
numbers of cores seen at each stage.


title:
INTEGRAL IGR J18135-1751=HESS J1813-178: A new cosmic high energy
  accelerator from keV to TeV

abstract:
  We report the discovery of a soft gamma ray source, namely IGR J18135-1751,
detected with the IBIS imager on board the INTEGRAL satellite. The source is
persistent and has a 20-100 keV luminosity of $\sim$5.7 $\times$ 10$^{34}$ erg
s$^{-1}$ (assuming a distance of 4kpc). This source is coincident with one of
the eight unidentified objects recently reported by the HESS collaboration as
part of the first TeV survey of the inner part of the Galaxy. Two of these new
sources found along the Galactic plane, HESS J1813-178 and HESS J1614-518, have
no obvious lower energy counterpart, a fact that motivated the suggestion that
they might be dark cosmic ray accelerators. HESS J1813-178 has a strongly
absorbed X-ray counterpart, the ASCA source AGPS273.4-17.8, showing a power law
spectrum with photon index $\sim$ 1.8 and a total (galactic plus intrinsic)
absorption corresponding to N$_H$ $\sim$5 $\times$ 10$^{22}$ cm$^{-2}$. We
hypothesize that the source is a pulsar wind nebula embedded in its supernova
remnant. The lack of X/gamma-ray variability, the radio morphology and the ASCA
spectrum are all compatible with this interpretation. In any case we rule out
the hypothesis that HESS J1813-178 belongs to a new class of TeV objects or
that it is a cosmic "dark particle" accelerator.


title: Periodic Variability During the X-ray Decline of 4U 1636-53

abstract:
  We report the onset of a large amplitude, statistically significant
periodicity (~46 d) in the RXTE/ASM data of the prototype X-ray burster 4U
1636-53, the X-ray flux of which has been gradually declining over the last
four years. This behaviour is remarkably similar to that observed in the
neutron star LMXB KS 1731-260, which is a long-term transient. We also report
on an INTEGRAL/IBIS observation of 4U 1636-53 during its decline phase, and
find that the hard X-ray flux (20-100 keV) indicates an apparent
anti-correlation with soft X-rays (2-12 keV). We argue that 4U 1636-53 is
transiting from activity to quiescence, as occurred in KS 1731-260. We also
suggest that the variability during the X-ray decline is the result of an
accretion rate variability related to the X-ray irradiation of the disc.


title:
A first look with Chandra at SGR 1806-20 after the Giant Flare:
  significant spectral softening and rapid flux decay

abstract:
  We report on the results of a ~30 ks Chandra pointing of the soft gamma-ray
repeater SGR 1806-20, the first X-ray observation with high spectral resolution
performed after the 2004 December 27 Giant Flare. The source was found in a
bursting active phase and with a significantly softer spectrum than that of the
latest observations before the Giant Flare. The observed flux in the 2-10 keV
range was ~2.2 x10^-11 erg/s/cm^2, about 20% lower than that measured three
months before the event. This indicates that, although its giant flare was ~100
times more intense than those previously observed in two other soft gamma-ray
repeaters, the post flare X-ray flux decay of SGR 1806-20 has been much faster.
The pulsed fraction was about 3%, a smaller value than that observed before the
flare. We discuss the different properties of the post-flare evolution of SGR
1806-20 in comparison to those of SGR 1900+14 and interpret the results as a
strong evidence that a magnetospheric untwisting occurred (or is occurring)
after the Giant Flare.


title: The role of black hole mass in quasar radio activity

abstract:
  We use a homogeneous sample of about 300, 0.3 <~ z <~ 3, radio-loud quasars
drawn from the FIRST and 2dF QSO surveys to investigate a possible dependence
of radio activity on black-hole mass. By analyzing composite spectra for the
populations of radio-quiet and radio-loud QSOs -- chosen to have the same
redshift and luminosity distribution -- we find with high statistical
significance that radio-loud quasars are on average associated with black holes
of masses ~10^{8.6} M_sun, about twice as large as those measured for
radio-quiet quasars (~10^{8.3} M_sun). We also find a clear dependence of black
hole mass on optical luminosity of the form log (M_BH/M_sun)_{RL}= 8.57(\pm
0.06) - 0.27(\pm 0.06) (M_B + 24.5) and log (M_BH/M_sun)_{RQ}= 8.43(\pm 0.05)
-0.32(\pm 0.06) (M_B + 24.5), respectively for the case of radio-loud and
radio-quiet quasars. It is intriguing to note that these two trends run roughly
parallel to each other, implying that radio-loud quasars are associated to
black holes more massive than those producing the radio-quiet case at all
sampled luminosities. On the other hand, in the case of radio-loud quasars, we
find evidence for only a weak (if any) dependence of the black hole mass on
radio power. The above findings seem to support the belief that there exists --
at a given optical luminosity -- a threshold black hole mass associated with
the onset of significant radio activity such as that of radio-loud QSOs;
however, once the activity is triggered, there appears to be very little
connection between black hole mass and level of radio output.


title:
An Analysis of Fundamental Waffle Mode in Early AEOS Adaptive Optics
  Images

abstract:
  Adaptive optics (AO) systems have significantly improved astronomical imaging
capabilities over the last decade, and are revolutionizing the kinds of science
possible with 4-5m class ground-based telescopes. A thorough understanding of
AO system performance at the telescope can enable new frontiers of science as
observations push AO systems to their performance limits. We look at recent
advances with wave front reconstruction (WFR) on the Advanced Electro-Optical
System (AEOS) 3.6 m telescope to show how progress made in improving WFR can be
measured directly in improved science images. We describe how a "waffle mode"
wave front error (which is not sensed by a Fried geometry Shack-Hartmann wave
front sensor) affects the AO point-spread function (PSF). We model details of
AEOS AO to simulate a PSF which matches the actual AO PSF in the I-band, and
show that while the older observed AEOS PSF contained several times more waffle
error than expected, improved WFR techniques noticeably improve AEOS AO
performance. We estimate the impact of these improved WFRs on H-band imaging at
AEOS, chosen based on the optimization of the Lyot Project near-infrared
coronagraph at this bandpass.


title: Cosmic Ray Spectral Deformation Caused by Energy Determination Errors

abstract:
  Using simulation methods, distortion effects on energy spectra caused by
errors in the energy determination have been investigated. For cosmic ray
proton spectra, falling steeply with kinetic energy E as E-2.7, significant
effects appear. When magnetic spectrometers are used to determine the energy,
the relative error increases linearly with the energy and distortions with a
sinusoidal form appear starting at an energy that depends significantly on the
error distribution but at an energy lower than that corresponding to the
Maximum Detectable Rigidity of the spectrometer. The effect should be taken
into consideration when comparing data from different experiments, often having
different error distributions.


title:
Fast electron slowing-down and diffusion in a high temperature coronal
  X-ray source

abstract:
  Finite thermal velocity modifications to electron slowing-down rates may be
important for the deduction of solar flare total electron energy. Here we treat
both slowing-down and velocity diffusion of electrons in the corona at flare
temperatures, for the case of a simple, spatially homogeneous source. Including
velocity diffusion yields a consistent treatment of both `accelerated' and
`thermal' electrons. It also emphasises that one may not invoke finite thermal
velocity target effects on electron lifetimes without simultaneously treating
the contribution to the observed X-ray spectrum from thermal electrons. We
present model calculations of the X-ray spectra resulting from injection of a
power-law energy distribution of electrons into a source with finite
temperature. Reducing the power-law distribution low-energy cutoff to lower and
lower energies only increases the relative magnitude of the thermal component
of the spectrum, because the lowest energy electrons simply join the background
thermal distribution. Acceptable fits to RHESSI flare data are obtained using
this model. These also demonstrate, however, that observed spectra may in
consequence be acceptably consistent with rather a wide range of injected
electron parameters.


title: Slow-roll Inflation for Generalized Two-Field Lagrangians

abstract:
  We study the slow-roll regime of two field inflation, in which the two fields
are also coupled through their kinetic terms. Such Lagrangians are motivated by
particle physics and by scalar-tensor theories studied in the Einstein frame.
We compute the power spectra of adiabatic and isocurvature perturbations on
large scales to first order in the slow-roll parameters. We discuss the
relevance of the extra coupling terms for the amplitude and indexes of the
power spectra. Beyond the consistency condition which involves the amplitude of
gravitational waves, additional relations may be found in particular models
based on such Lagrangians: as an example, we find an additional general
consistency condition in implicit form for Brans-Dicke theory in the Einstein
frame.


title:
An Asymmetric, Energetic Type Ic Supernova Viewed Off-Axis, and a Link
  to Gamma-Ray Bursts

abstract:
  Type Ic supernovae, the explosions following the core collapse of massive
stars that have previously lost their hydrogen and helium envelopes, are
particularly interesting because of the link with long-duration gamma-ray
bursts. Although indications exist that these explosions are aspherical, direct
evidence has still been missing. Late-time observations of SN 2003jd, a
luminous Type Ic supernova, provide such evidence. Recent Subaru and Keck
spectra reveal double-peaked profiles in the nebular lines of neutral oxygen
and magnesium. These profiles are different from those of known Type Ic
supernovae, with or without a gamma-ray burst, and they can be understood if SN
2003jd was an aspherical, axisymmetric explosion viewed from near the
equatorial plane. If SN 2003jd was associated with a gamma-ray burst, we missed
the burst as it was pointing away from us.


title:
The Piecewise Parabolic Method for Multidimensional Relativistic Fluid
  Dynamics

abstract:
  We present an extension of the Piecewise Parabolic Method to special
relativistic fluid dynamics in multidimensions. The scheme is conservative,
dimensionally unsplit, and suitable for a general equation of state. Temporal
evolution is second-order accurate and employs characteristic projection
operators; spatial interpolation is piece-wise parabolic making the scheme
third-order accurate in smooth regions of the flow away from discontinuities.
The algorithm is written for a general system of orthogonal curvilinear
coordinates and can be used for computations in non-cartesian geometries. A
non-linear iterative Riemann solver based on the two-shock approximation is
used in flux calculation. In this approximation, an initial discontinuity
decays into a set of discontinuous waves only implying that, in particular,
rarefaction waves are treated as flow discontinuities. We also present a new
and simple equation of state which approximates the exact result for the
relativistic perfect gas with high accuracy. The strength of the new method is
demonstrated in a series of numerical tests and more complex simulations in
one, two and three dimensions.


title: Precise reddening and metallicity of NGC6752 from FLAMES spectra

abstract:
  (abridged) Accurate reddenings for Globular Clusters could be obtained by
comparing the colour-temperature obtained using temperatures from
reddening-free indicator (Halpha), with that given by standard
colour-temperature calibrations. From a single 1300 seconds exposure with
FLAMES at VLT2 we obtained spectra centred on Halpha (R=6000, 5<S/N<50) for 120
stars near the turn-off of NGC6752. This set of spectra was used to derive
effective temperatures from fittings of Halpha profiles with typical errors of
about +/- 200 K and reddening estimates with individual errors of 0.05 mag.
Averaging all individual reddenings, a high precision reddening estimate has
been obtained for the cluster: E(B-V)=0.046 +/- 0.005. The same exposure
provided UVES spectra of seven stars near the red giant branch bump (R=40000,
20<S/N<40) that provided Fe abundances with internal errors of 0.026 dex, and
with average metallicity [Fe/H]= -1.48 +/- 0.01 +/- 0.06 dex (random +
systematic). Abundances were obtained for several other elements, allowing e.g.
an accurate estimate of the ratio between the alpha-elements and Fe
([alpha/Fe]=+0.27 +/- 0.01). The O-Na anticorrelation is evident from our UVES
data, in agreement with past results. This analysis shows the power of FLAMES
for analysis of globular clusters: the accurate reddenings and metal abundances
obtained by a procedure like that described here, combined with distance
determinations from cluster dynamics or main sequence fitting, and high quality
colour-magnitude diagrams, could allow derivation of ages with errors below 1
Gyr for individual globular clusters.