title:
Confirmation of the $\eps$ -- $\eiso$ (Amati) relation from the X-ray
  flash XRF 050416A observed by Swift/BAT

abstract:
  We report Swift Burst Alert Telescope (BAT) observations of the X-ray Flash
(XRF) XRF 050416A. The fluence ratio between the 15-25 keV and 25-50 keV energy
bands of this event is 1.5, thus making it the softest gamma-ray burst (GRB)
observed by BAT so far. The spectrum is well fitted by the Band function with
E^{\rm obs}_{\rm peak} of 15.0_{-2.7}^{+2.3} keV. Assuming the redshift of the
host galaxy (z = 0.6535), the isotropic-equivalent radiated energy E_{\rm iso}
and the peak energy at the GRB rest frame (E^{\rm src}_{\rm peak}) of XRF
050416A are not only consistent with the correlation found by Amati et al. and
extended to XRFs by Sakamoto et al., but also fill-in the gap of this relation
around the 30 - 80 keV range of E^{\rm src}_{\rm peak}. This result tightens
the validity of the E^{\rm src}_{\rm peak} - E_{\rm iso} relation from XRFs to
GRBs.
  We also find that the jet break time estimated using the empirical relation
between E^{\rm src}_{\rm peak} and the collimation corrected energy E_{\gamma}
is inconsistent with the afterglow observation by Swift X-ray Telescope. This
could be due to the extra external shock emission overlaid around the jet break
time or to the non existence of a jet break feature for XRF, which might be a
further challenging for GRB jet emission, models and XRF/GRB unification
scenarios.


title:
Dynamic tides in rotating objects: orbital circularisation of extra
  solar planets for realistic planet models

abstract:
  (abbreviated) We consider the problem of the tidal capture or circularisation
from large eccentricity of a uniformly rotating object. We extend the
self-adjoint formalism introduced in Papaloizou \& Ivanov 2005 (PI) to derive
general expressions for the energy and angular momentum transfered when the
planet or a star passes through periastron in a parabolic or highly eccentric
orbit around a central mass, without making a low frequency approximation as
was done in PI. We show how these can be adapted to the low frequency limit in
which only inertial modes contribute to the energy and angular momentum
transfer. We calculate the inertial mode eigenspectrum for planet models of one
and five Jupiter masses $M_J,$ without a solid core, with different radii
corresponding to different ages.
  We consider the multi-passage problem when there is no dissipation finding
that stochastic instability resulting in the stochastic gain of inertial mode
energy over many periastron passages occurs under similar conditions to those
already found for the $f$ modes.
  We apply our calculations to the problem of the tidal circularisation of the
orbits of the extra solar planets in a state of pseudo synchronisation, and
find that inertial mode excitation dominates the tidal interaction for $1 M_J$
planets that start with semi- major axes less than $10 AU$ and end up on
circular orbits with final period in the $4-6$ day range. It is potentially
able to account for initial circularisation up to a final $6$ day period within
a few $Gyr$ But in the case of $5M_J$ oscillation modes excited in the star are
more important.


title: NLTE analyses of sdB stars: progress and prospects

abstract:
  We report on preliminary results of a hybrid non-LTE analysis of
high-resolution, high-S/N spectra of the helium-rich subdwarf B star Feige49
and the helium-poor sdB HD205805. Non-LTE effects are found to have a notable
impact on the stellar parameter and abundance determination. In particular the
HeI lines show significant deviations from detailed balance, with the computed
equivalent widths strengthened by up to ~35%. Non-LTE abundance corrections for
the metals (C, N, O, Mg, S) are of the order ~0.05-0.25 dex on the mean, while
corrections of up to ~0.7 dex are derived for individual transitions. The
non-LTE approach reduces systematic trends and the statistical uncertainties in
the abundance determination. Consequently, non-LTE analyses of a larger sample
of objects have the potential to put much tighter constraints on the formation
history of the different sdB populations than currently discussed.


title: Improved helium line formation for EHe stars

abstract:
  Quantitative analyses of extreme helium stars to date face the difficulty
that theory fails to reproduce the observed helium lines in their entirety,
wings and line cores. Here, we demonstrate how the issues can be resolved using
state-of-the-art non-LTE line formation for these chemically peculiar objects.
Two unique B-type objects are discussed in detail, the pulsating variable V652
Her and the metal-poor star HD144941. The improved non-LTE computations for
helium show that analyses assuming LTE or based on older non-LTE model atoms
can predict equivalent widths, for the HeI 10830A transition in particular, in
error by up to a factor ~3. Our modelling approach also succeeds in largely
resolving the general mismatch for effective temperatures of EHe stars derived
from ionization equilibria and from spectral energy distributions.


title: Non-LTE metal abundances in V652 Her and HD144941

abstract:
  Two evolutionary scenarios are proposed for the formation of extreme helium
stars: a post-AGB star suffering from a late thermal pulse, or the merger of
two white dwarfs. An identification of the evolutionary channel for individual
objects has to rely on surface abundances. We present preliminary results from
a non-LTE analysis of CNO, Mg and S for two unique objects, V652 Her and
HD144941. Non-LTE abundance corrections for these elements range from
negligible values to ~0.7 dex. Non-LTE effects typically lead to systematic
shifts in the abundances relative to LTE and reduce the uncertainties.


title:
Implications for the Cosmic Reionization from the Optical Afterglow
  Spectrum of the Gamma-Ray Burst 050904 at z = 6.3

abstract:
  The gamma-ray burst (GRB) 050904 at z = 6.3 provides the first opportunity of
probing the intergalactic medium (IGM) by GRBs at the epoch of the
reionization. Here we present a spectral modeling analysis of the optical
afterglow spectrum taken by the Subaru Telescope, aiming to constrain the
reionization history. The spectrum shows a clear damping wing at wavelengths
redward of the Lyman break, and the wing shape can be fit either by a damped Ly
alpha system with a column density of log (N_HI/cm^{-2}) ~ 21.6 at a redshift
close to the detected metal absorption lines (z_metal = 6.295), or by almost
neutral IGM extending to a slightly higher redshift of z_{IGM,u} ~ 6.36. In the
latter case, the difference from z_metal may be explained by acceleration of
metal absorbing shells by the activities of the GRB or its progenitor. However,
we exclude this possibility by using the light transmission feature around the
Ly beta resonance, leading to a firm upper limit of z_{IGM,u} < 6.314. We then
show an evidence that the IGM was largely ionized already at z=6.3, with the
best-fit neutral fraction of IGM, x_HI = N_HI/N_H = 0.00, and upper limits of
x_HI < 0.17 and 0.60 at 68 and 95% C.L., respectively. This is the first direct
and quantitative upper limit on x_HI at z > 6. Various systematic uncertainties
are examined, but none of them appears large enough to change this conclusion.
To get further information on the reionization, it is important to increase the
sample size of z >~ 6 GRBs, in order to find GRBs with low column densities
(log N_HI <~ 20) within their host galaxies, and for statistical studies of Ly
alpha line emission from host galaxies.


title: Evading the astrophysical limits on light pseudoscalars

abstract:
  We study the possibility of evading astrophysical bounds on light
pseudoscalars. We argue that the solar bounds can be evaded if we have a
sufficiently strong self coupling of the pseudoscalars. The required couplings
do not conflict with any known experimental bounds. We show that it is possible
to find a coupling range such that the results of the recent PVLAS experiment
are not in conflict with any astrophysical bounds.


title: The sense of rotation of subhaloes in cosmological dark matter haloes

abstract:
  We present a detailed analysis of the velocity distribution and orientation
of orbits of subhaloes in high resolution cosmological simulations of dark
matter haloes. We find a trend for substructure to preferentially revolve in
the same direction as the sense of rotation of the host halo: there is an
excess of prograde satellite haloes. Throughout our suite of nine host haloes
(eight cluster sized objects and one galactic halo) there are on average 59% of
the satellites corotating with the host. Even when including satellites out to
five virial radii of the host, the signal still remains pointing out the
relation of the signal with the infall pattern of subhaloes. However, the
fraction of prograde satellites weakens to about 53% when observing the data
along a (random) line-of-sight and deriving the distributions in a way an
observer would infer them. This decrease in the observed prograde fraction has
its origin in the technique used by the observer to determine the sense of
rotation, which results in a possible misclassification of non-circular orbits.
We conclude that the existence of satellites on corotating orbits is another
prediction of the cold dark matter structure formation scenario, although there
will be difficulties to verify it observationally. Since the galactic halo
simulation gave the same result as the cluster-sized simulations, we assume
that the fraction of prograde orbits is independent of the scale of the system,
though more galactic simulations would be necessary to confirm this.


title: The XMM-Newton Slew Survey: a wide-angle survey in the 0.2 - 12 keV band

abstract:
  The scientific data collected during slews of the XMM-Newton satellite are
used to construct a slew survey catalogue. This comprises of the order of 4000
sources detected in the EPIC-pn 0.2-12 keV band with exposures of less than 15s
and a sky coverage of about 6300 square degrees (source density ~0.65 per
square degree). Below 2 keV the sensitivity limit is comparable to the ROSAT
PSPC All-Sky Survey and the XMM-Newton slew survey offers long-term variablity
studies. Above 2 keV the survey will be a factor of 10 more sensitive than all
previous all-sky X-ray surveys. The slew survey is almost complementary to the
serendipitous survey compiled from pointed XMM-Newton observations. It is aimed
to release the first source catalogue by the end of 2005. Later slew
observations and detections will continuously be added. This paper discusses
the XMM-Newton slew survey also in a historical context.


title:
Accreting White Dwarfs among the Planetary Nebulae Most Luminous in [O
  III]5007 Emission

abstract:
  I propose that some of the most luminous planetary nebulae (PNs) are actually
proto-PNs, where a companion white dwarf (WD) accretes mass at a relatively
high rate from the post-asymptotic giant branch star that blew the nebula. The
WD sustains a continuous nuclear burning and ionizes the nebula. The WD is
luminous enough to make the dense nebula luminous in the [O III]5007 line, In
young stellar populations these WD accreting systems account for a small
fraction of [O III]-luminous PNs, but in old stellar populations these binaries
might account for most, or even all, of the [OIII]-luminous PNs. This might
explain the puzzling constant cutoff (maximum) [O III]5007 luminosity of the
planetary nebula luminosity function across different galaxy types.


title:
Correlated Fluctuations in Luminosity Distance and the (Surprising)
  Importance of Peculiar Motion in Supernova Surveys

abstract:
  Large scale structure introduces two different kinds of errors in the
luminosity distance estimates from standardizable candles such as supernovae Ia
(SNe) - a Poissonian scatter for each SN and a coherent component due to
correlated fluctuations between different SNe. Increasing the number of SNe
helps reduce the first type of error but not the second. The coherent component
has been largely ignored in forecasts of dark energy parameter estimation from
upcoming SN surveys. For instance it is commonly thought, based on Poissonian
considerations, that peculiar motion is unimportant, even for a low redshift SN
survey such as the Nearby Supernova Factory (SNfactory; z = 0.03 - 0.08), which
provides a useful anchor for future high redshift surveys by determining the SN
zero-point. We show that ignoring coherent peculiar motion leads to an
underestimate of the zero-point error by about a factor of 2, despite the fact
that SNfactory covers almost half of the sky. More generally, there are four
types of fluctuations: peculiar motion, gravitational lensing, gravitational
redshift and what is akin to the integrated Sachs-Wolfe effect. Peculiar motion
and lensing dominates at low and high redshifts respectively. Taking into
account all significant luminosity distance fluctuations due to large scale
structure leads to a degradation of up to 60% in the determination of the dark
energy equation of state from upcoming high redshift SN surveys, when used in
conjunction with a low redshift anchor such as the SNfactory. The most relevant
fluctuations are the coherent ones due to peculiar motion and the Poissonian
ones due to lensing, with peculiar motion playing the dominant role. We also
discuss to what extent the noise here can be viewed as a useful signal, and
whether corrections can be made to reduce the degradation.


title: Cluster infall in the concordance LCDM model

abstract:
  We perform statistical analyses of the infall of dark-matter onto clusters in
numerical simulations within the concordance LCDM model. By studying the infall
profile around clusters of different mass, we find a linear relation between
the maximum infall velocity and mass which reach 900km/s for the most massive
groups. The maximum infall velocity and the group mass follow a suitable power
law fit of the form, V_{inf}^{max} = (M/m_0)^{gamma}. By comparing the measured
infall velocity to the linear infall model with an exponential cutoff
introduced by Croft et al., we find that the best agreement is obtained for a
critical overdensity delta_c = 45. We study the dependence of the direction of
infall with respect to the cluster centres, and find that in the case of
massive groups, the maximum alignment occurs at scales r ~ 6Mpc/h. We obtain a
logarithmic power-law relation between the average infall angle and the group
mass. We also study the dependence of the results on the local dark-matter
density, finding a remarkable difference in the dynamical behaviour of low- and
high-density particles.


title:
Kinematics and Metallicity of M31 Red Giants: The Giant Southern Stream
  and Discovery of a Second Cold Component at R = 20 kpc

abstract:
  We present spectroscopic observations of red giant branch (RGB) stars in the
Andromeda spiral galaxy (M31), acquired with the DEIMOS instrument on the Keck
II 10-m telescope. The three fields targeted in this study are in the M31
spheroid, outer disk, and giant southern stream. In this paper, we focus on the
kinematics and chemical composition of RGB stars in the stream field located at
a projected distance of R = 20 kpc from M31's center. A mix of stellar
populations is found in this field. M31 RGB stars are isolated from Milky Way
dwarf star contaminants using a variety of spectral and photometric
diagnostics. The radial velocity distribution of RGB stars displays a clear
bimodality -- a primary peak centered at v = -513 km/s and a secondary one at v
= -417 km/s -- along with an underlying broad component that is presumably
representative of the smooth spheroid of M31. Both peaks are found to be
dynamically cold with intrinsic velocity dispersions of sigma(v) = 16 km/s. The
mean metallicity and metallicity dispersion of stars in the two peaks is also
found to be similar: [Fe/H] = -0.45 and sigma([Fe/H]) = 0.2. The observed
velocity of the primary peak is consistent with that predicted by dynamical
models for the stream, but there is no obvious explanation for the secondary
peak. The nature of the secondary cold population is unclear: it may represent:
(1) tidal debris from a satellite merger event that is superimposed on, but
unrelated to, the giant southern stream; (2) a wrapped around component of the
giant southern stream; (3) a warp or overdensity in M31's disk at R > 50 kpc
(this component is well above the outward extrapolation of the smooth
exponential disk brightness profile).


title:
Gamma Rays from Compton Scattering in the Jets of Microquasars:
  Application to LS 5039

abstract:
  Recent HESS observations show that microquasars in high-mass systems are
sources of VHE gamma-rays. A leptonic jet model for microquasar gamma-ray
emission is developed. Using the head-on approximation for the Compton cross
section and taking into account angular effects from the star's orbital motion,
we derive expressions to calculate the spectrum of gamma rays when nonthermal
jet electrons Compton-scatter photons of the stellar radiation field.
Calculations are presented for power-law distributions of nonthermal electrons
that are assumed to be isotropically distributed in the comoving jet frame, and
applied to $\gamma$-ray observations of LS 5039. We conclude that (1) the TeV
emission measured with HESS cannot result only from Compton-scattered stellar
radiation (CSSR), but could be synchrotron self-Compton (SSC) emission or a
combination of CSSR and SSC; (2) fitting both the HESS data and the EGRET data
associated with LS 5039 requires a very improbable leptonic model with a very
hard electron spectrum. Because the gamma rays would be variable in a leptonic
jet model, the data sets are unlikely to be representative of a simultaneously
measured gamma-ray spectrum. We therefore attribute EGRET gamma rays primarily
to CSSR emission, and HESS gamma rays to SSC emission. Detection of periodic
modulation of the TeV emission from LS 5039 would favor a leptonic SSC or
cascade hadron origin of the emission in the inner jet, whereas stochastic
variability alone would support a more extended leptonic model. The puzzle of
the EGRET gamma rays from LS 5039 will be quickly solved with GLAST. (Abridged)


title:
High Metallicity, Photoionised Gas in Intergalactic Large-Scale
  Filaments

abstract:
  We present high-resolution UV spectra of absorption-line systems toward the
low-z QSO HS0624+6907 (z=0.3700). Coupled with spectroscopic galaxy redshifts,
we find that many of these absorbers are integalactic gas clouds distributed
within large-scale structures. The gas is cool (T<10^5 K) and has relatively
high metallicity (Z/Z_sol>0.9). STIS data reveal a cluster of 13 HI Lyman alpha
lines within a 1000 km/s interval at z=0.0635. We find 10 galaxies at this
redshift with impact parameters ranging from 135 h^-1 kpc to 1.37 h^-1 Mpc. We
attribute the HI Lya absorptions to intragroup medium gas, possibly from a
large-scale filament viewed along its long axis. Remarkably, the metallicity is
near-solar, [M/H] = -0.05 +/- 0.4 (2 sigma uncertainty), yet the nearest galaxy
which might pollute the IGM is at least 135 h_70^-1 kpc away. Tidal stripping
from nearby galaxies appears to be the most likely origin of this highly
enriched, cool gas. More than six Abell galaxy clusters are found within 4
degree of the sight line suggesting that the QSO line of sight passes near a
node in the cosmic web. At z~0.077, we find absorption systems as well as
galaxies at the redshift of the nearby clusters Abell 564 and Abell 559. We
conclude that the sight line pierces a filament of gas and galaxies feeding
into these clusters. The absorber at z_abs = 0.07573 associated with Abell
564/559 also has a high metallicity with [C/H] > -0.6, but again the closest
galaxy is relatively far from the sight line (293 h^-1 kpc).


title: Gamma Ray Bursts as Possible High Energy Sources

abstract:
  Gamma-ray bursts are known to be sources of high-energy gamma rays, and are
likely to be sources of high-energy cosmic rays and neutrinos. Following a
short review of observations of GRBs at multi-MeV energies and above, the
physics of leptonic and hadronic models of GRBs is summarized. Evidence for two
components in BATSE and EGRET/TASC data suggest that GRBs are sources of
high-energy cosmic rays. GLAST observations will reveal the high-energy
gamma-ray power and energy releases from GRBs, and will provide detailed
knowledge of anomalous high-energy emission components, but confirmation of
cosmic ray acceleration must await 100 TeV -- PeV neutrino detection from GRBs.


title:
Surface photometry and structure of high redshift disk galaxies in the
  HDF-S NICMOS field

abstract:
  A photometric study of 22 disk galaxies at redshifs z=0.5-2.6 is conducted,
using deep NICMOS J and H band and STIS open mode observations of the HDF-S
NICMOS parallel field. Rest-frame B-profiles and (U-V) color profiles are
constructed. A number of disks show steeper decrease of luminosity than
exponential, referring to disk truncation. Shape of the luminosity profiles
does not vary with redshift, but galactic sizes decrease significantly. (U-V)
colors and color gradients suggest more intense and centrally concentrated star
formation at earlier epochs. On the basis of (U-V) color and chemical evolution
models, the disks at z~2.5 have formed between z=3.5-7. The studied parameters
are idependent of absolute B luminosity within the sample.


title: Very Small-Scale Clustering and Merger Rate of Luminous Red Galaxies

abstract:
  We present the small-scale (0.01<r<8 h^{-1} Mpc) projected correlation
function w_p(r_p) and real space correlation function xi(r) of 24520 luminous
early-type galaxies from the Sloan Digital Sky Survey Luminous Red Galaxy (LRG)
sample (0.16<z<0.36). ``Fiber collision'' incompleteness of the SDSS
spectroscopic sample at scales smaller than 55 arcseconds prevents measurements
of the correlation function for LRGs on scales smaller than ~0.3 Mpc by the
usual methods. In this work, we cross-correlate the spectroscopic sample with
the imaging sample, with a weighting scheme to account for the collisions,
extensively tested against mock catalogs. We correct for photometric biases in
the SDSS imaging of close galaxy pairs. We find that the correlation function
xi(r) is surprisingly close to a r^{-2} power law over more than 4 orders of
magnitude in separation r. This result is too steep at small scales to be
explained in current versions of the halo model for galaxy clustering. We infer
an LRG-LRG merger rate of less than or similar to 0.6 Gyr^{-1} Gpc^{-3} for
this sample. This result suggests that the LRG-LRG mergers are not the main
mode of mass growth for LRGs at z<0.36.


title:
The Beylkin-Cramer Summation Rule and A New Fast Algorithm of Cosmic
  Statistics for Large Data Sets

abstract:
  Based on the Beylkin-Cramer summation rule, we introduce a new fast algorithm
that enable us to explore the high order statistics efficiently in large data
sets. Central to this technique is to make decomposition both of fields and
operators within the framework of multi-resolution analysis (MRA), and realize
theirs discrete representations. Accordingly, a homogenous point process could
be equivalently described by a operation of a Toeplitz matrix on a vector,
which is accomplished by making use of fast Fourier transformation. The
algorithm could be applied widely in the cosmic statistics to tackle large data
sets. Especially, we demonstrate this novel technique using the spherical,
cubic and cylinder counts in cells respectively. The numerical test shows that
the algorithm produces an excellent agreement with the expected results.
Moreover, the algorithm introduces naturally a sharp-filter, which is capable
of suppressing shot noise in weak signals. In the numerical procedures, the
algorithm is somewhat similar to particle-mesh (PM) methods in N-body
simulations. As scaled with $O(N\log N)$, it is significantly faster than the
current particle-based methods, and its computational cost does not relies on
shape or size of sampling cells. In addition, based on this technique, we
propose further a simple fast scheme to compute the second statistics for
cosmic density fields and justify it using simulation samples. Hopefully, the
technique developed here allows us to make a comprehensive study of
non-Guassianity of the cosmic fields in high precision cosmology. A specific
implementation of the algorithm is publicly available upon request to the
author.


title: A Chandra X-ray observation of the globular cluster Terzan 1

abstract:
  We present a 19 ks Chandra ACIS-S observation of the globular cluster Terzan
1. Fourteen sources are detected within 1.4 arcmin of the cluster center with 2
of these sources predicted to be not associated with the cluster (background
AGN or foreground objects). The neutron star X-ray transient, X1732-304, has
previously been observed in outburst within this globular cluster with the
outburst seen to last for at least 12 years. Here we find 4 sources that are
consistent with the ROSAT position for this transient, but none of the sources
are fully consistent with the position of a radio source detected with the VLA
that is likely associated with the transient. The most likely candidate for the
quiescent counterpart of the transient has a relatively soft spectrum and an
unabsorbed 0.5-10 keV luminosity of 2.6E32 ergs/s, quite typical of other
quiescent neutron stars. Assuming standard core cooling, from the quiescent
flux of this source we predict long (>400 yr) quiescent episodes to allow the
neutron star to cool. Alternatively, enhanced core cooling processes are needed
to cool down the core. However, if we do not detect the quiescent counterpart
of the transient this gives an unabsorbed 0.5-10 keV luminosity upper limit of
8E31 ergs/s. We also discuss other X-ray sources within the globular cluster.
  From the estimated stellar encouter rate of this cluster we find that the
number of sources we detect is significantly higher than expected by the
relationship of Pooley et al. (2003).


title:
Redshifts and Velocity Dispersions of Galaxy Clusters in the
  Horologium-Reticulum Supercluster

abstract:
  We present 118 new optical redshifts for galaxies in 12 clusters in the
Horologium-Reticulum supercluster (HRS) of galaxies. For 76 galaxies, the data
were obtained with the Dual Beam Spectrograph on the 2.3m telescope of the
Australian National University at Siding Spring Observatory. After combining 42
previously unpublished redshifts with our new sample, we determine mean
redshifts and velocity dispersions for 13 clusters, in which previous
observational data were sparse. In six of the 13 clusters, the newly determined
mean redshifts differ by more than 750 km/s from the published values. In the
case of three clusters, A3047, A3109, and A3120, the redshift data indicate the
presence of multiple components along the line of sight. The new cluster
redshifts, when combined with other reliable mean redshifts for clusters in the
HRS, are found to be distinctly bi-modal. Furthermore, the two redshift
components are consistent with the bi-modal redshift distribution found for the
inter-cluster galaxies in the HRS by Fleenor et al. (2005).


title: Modelling and Correcting the Time-Dependent ACS PSF

abstract:
  The ability to accurately measure the shapes of faint objects in images taken
with the Advanced Camera for Surveys(ACS) on the Hubble Space Telescope (HST)
depends upon detailed knowledge of the Point Spread Function (PSF). We show
that thermal fluctuations cause the PSF of the ACS Wide Field Camera (WFC) to
vary over time. We describe a modified version of the TinyTim PSF modeling
software to create artificial grids of stars across the ACS field of view at a
range of telescope focus values. These models closely resemble the stars in
real ACS images. Using ~10 bright stars in a real image, we have been able to
measure HST's apparent focus at the time of the exposure. TinyTim can then be
used to model the PSF at any position on the ACS field of view. This obviates
the need for images of dense stellar fields at different focus values, or
interpolation between the few observed stars. We show that residual differences
between our TinyTim models and real data are likely due to the effects of
Charge Transfer Efficiency (CTE) degradation. Furthermore, we discuss
stochastic noise that is added to the shape of point sources when distortion is
removed, and we present Multidrizzle parameters that are optimal for weak
lensing science. Specifically, we find that reducing the Multidrizzle output
pixel scale and choosing a Gaussian kernel significantly stabilizes the
resulting PSF after image combination, while still eliminating cosmic rays/bad
pixels, and correcting the large geometric distortion in the ACS. We discuss
future plans, which include more detailed study of the effects of CTE
degradation on object shapes and releasing our TinyTim models to the
astronomical community.


title:
037-B327 in M31: Luminous Globular Cluster or Core of a Former Dwarf
  Spheroidal Companion to M31?

abstract:
  037-B327 is of interest because it is both the most luminous and the most
highly reddened cluster known in M31. Deep observations with the Advanced
Camera for Surveys on the Hubble Space Telescope provide photometric data in
the F606W band, and also show that this cluster is crossed by a dust lane. We
determined the structural parameters of 037-B327 by fitting the observed
surface brightness distribution to a King model with r_c=0.72" (=2.69 pc), and
r_t=5.87" (=21.93 pc), and a concentration index c=log(r_t/r_c)=0.91. The
surface brightness profile appears to be essentially flat within 0.25" of the
center and shows no signs of core collapse. Although the dust lane affects the
photometry, the King model fits the surface brightness profile well except for
the regions badly affected by the dust lane. We also calculate the half-light
radius r_h=1.11" (=4.15 pc). Combined with previous photometry, we find that
this object falls in the same region of the M_V versus log R_h diagram as do
Omega Centauri, M54 and NGC 2419 in the Milky Way and the massive cluster G1 in
M31. All four of these objects have been claimed to be the stripped cores of
former dwarf galaxies. This suggests that 037-B327 may also be the stripped
core of a former dwarf companion to M31.


title:
Age Estimations of M31 Globular Clusters from Their Spectral Energy
  Distributions

abstract:
  This paper presents accurate spectral energy distributions (SEDs) of 16 M31
globular clusters (GCs) confirmed by spectroscopy and/or high
spatial-resolution imaging, as well as 30 M31 globular cluster candidates
detected by Mochejska et al. Most of these candidates have m_V > 18, deeper
than previous searches, and these candidates have not yet been confirmed to be
globular clusters. The SEDs of these clusters and candidates are obtained as
part of the BATC Multicolor Survey of the Sky, in which the
spectrophotometrically-calibrated CCD images of M31 in 13 intermediate-band
filters from 4000 to 10000 A were observed. These filters are specifically
designed to exclude most of the bright and variable night-sky emission lines
including the OH forest. In comparison to the SEDs of true GCs, we find that
some of the candidate objects are not GCs in M31. SED fits show that
theoretical simple stellar population (SSP) models can fit the true GCs very
well. We estimate the ages of these GCs by comparing with SSP models. We find
that, the M31 clusters range in age from a few ten Myr to a few Gyr old, as
well as old GCs, confirming the conclusion that has been found by Barmby et a,
Williams & Hodge, Beasley et al., Burstein et al. and Puzia et al. in their
investigations of the SEDs of M31 globular clusters.


title:
Spectral Energy Distributions of M81 Globular Clusters in BATC
  Multicolor Survey

abstract:
  In this paper, we give the spectral energy distributions of 42 M81 globular
clusters in 13 intermediate-band filters from 4000 to 10000 A, using the CCD
images of M81 observed as part of the BATC multicolor survey of the Sky. The
BATC multicolor filter system is specifically designed to exclude most of the
bright and variable night-sky emission lines including the OH forest. Hence, it
can present accurate SEDs of the observed objects. These spectral energy
distributions are low-resolution spectra, and can reflect the stellar
populations of the globular clusters. This paper confirms the conclusions of
Schroder et al. that, M81 contains clusters as young as a few Gyrs, which also
were observed in both M31 and M33


title: Development of Multi-Fourier Transform interferometer :Fundamental

abstract:
  We propose the development of an instrument by the Martin & Puplett-type
Fourier Transform Spectrometer to applying the aperture synthesis technique in
millimeter and submillimeter waves. We call this equipment the Multi-Fourier
Transform interferometer (MuFT). MuFT performs a wide band imaging,
spectroscopy and polarimetry in millimeter and submillimeter wavelengths. We
describe the fundamentals of MuFT, and give an example of one potential
implementation. Full description of the observables by MuFT are provided. A
physical explanation of the observability of the complex visibility by MuFT is
given. Fundamental restrictions on observations with MuFT, eg. limits on
spectral and spatial resolutions and field-of-view, are discussed. The
advantages of MuFT are also summarized.


title: Massive elliptical galaxies : From cores to haloes

abstract:
  In the context of recent observational results that show massive ellipticals
were in place at high redshifts, we reassess the status of monolithic collapse
in a LCDM universe. Using a sample of over 2000 galaxies from the Sloan Digital
Sky Survey, by comparing the dynamical mass and stellar mass (estimated from
colours) we find that ellipticals have `cores' which are baryon-dominated
within their half-light radius. These galaxies correspond to 3-sigma peaks in
the spherical collapse model if the total mass in the halo is assumed to be 20
times the dynamical mass within the half-light radius. This value yields
stellar mass to total mass ratios of 8%, compared to a cosmological baryon
fraction of 18% derived from WMAP3 alone. We further develop a method for
reconstructing the concentration halo parameter c of the progenitors of these
galaxies by utilizing adiabatic contraction. Although the analysis is done
within the framework of monolithic collapse, the resulting distribution of c is
log-normal with a peak value of c~3-10 and a distribution width similar to the
results of N-body simulations. We also derive scaling relations between stellar
and dynamical mass and the velocity dispersion, and find that these are
sufficient to recover the tilt of the fundamental plane.


title:
Evidence of a Change in the Long Term Spin-down Rate of the X-ray Pulsar
  4U 1907+09

abstract:
  We analyzed RXTE archival observations of 4U 1907+09 between 17 February 1996
and 6 March 2002. The pulse timing analysis showed that the source stayed at
almost {\bf{constant}} period around August 1998 and then started to spin-down
at a rate of $(-1.887\mp 0.042)\times 10^{-14}$ Hz s$^-1$ which is $\sim$ 0.60
times lower than the long term ($\sim 15$ years) spin-down rate (Baykal et al.
2001). Our pulse frequency measurements for the first time resolved significant
spin-down rate variations since the discovery of the source. We also presented
orbital phase resolved X-ray spectra during two stable spin down episodes
during November 1996 - December 1997 and March 2001 - March 2002. The source
has been known to have two orbitally locked flares. We found that X-ray flux
and spectral parameters except Hydrogen column density agreed with each other
during the flares.We interpreted the similar values of X-ray fluxes as an
indication of the fact that the source accretes not only via transient
retrograde accretion disc (in't Zand et al. 1998) but also via the stellar wind
of the companion (Roberts et al. 2001), so that the variation of the accretion
rate from the disc does not cause significant variation in the observed X-ray
flux. Lack of significant change in spectral parameters except Hydrogen column
density was interpreted as a sign of the fact that the change in the spin-down
rate of the source was not accompanied by a significant variation in the
accretion geometry.


title: Calibration of Gamma-Ray Burst Luminosity Indicators

abstract:
  Several gamma-ray burst (GRB) luminosity indicators (LIs)have been proposed.
Unlike SNe Ia, calibration of GRB LIs using a low-redshift sample is difficult.
Based on the Bayesian theory, here we propose an approach to calibrate these
LIs without introducing a low-redshift GRB sample. The essential points of our
approach include, (1) calibrate the power-law indices in the LIs with a sample
of GRBs in a narrow redshift range (Delta z); and (2) marginalize the
coefficient of the LIs over a reasonable range of cosmological parameters. We
take our newly discovered multivariable GRB LIs as an example and test the
validity of our approach through simulations. We show that while the
coefficient strongly depends on the cosmological parameters, the power-law
indices do not as long as Delta z is small enough. The selection of Delta z for
a particular GRB sample could be judged according to the size and the
observational uncertainty of the sample. There is no preferable redshift to
perform the calibration of the indices, while a lower redshift is preferable
for the marginalization of the coefficient. The best strategy would be to
collect GRBs within a narrow redshift bin around a fiducial intermediate
redshift (e.g. z~1 or z~2), since the observed GRB redshift distribution is
found to peak around z=(1 - 2.5). Our simulation suggests that with the current
observational precision of measuring GRB isotropic energy, spectral break
energy, and the optical temporal break time, 25 GRBs within a redshift bin of
Delta z ~ 0.30 would give fine calibration to our luminosity
indicator(abridged).


title:
Two-dimensional radiation-hydrodynamic model for limit-cycle
  oscillations of luminous accretion disks

abstract:
  We investigate the time evolution of luminous accretion disks around black
holes, conducting the two-dimensional radiation-hydrodynamic simulations. We
adopt the alpha prescription for the viscosity. The radial-azimuthal component
of viscous stress tensor is assumed to be proportional to the total pressure in
the optically thick region, while the gas pressure in the optically thin
regime. The viscosity parameter, alpha, is taken to be 0.1. We find the
limit-cycle variation in luminosity between high and low states. When we set
the mass input rate from the outer disk boundary to be 100 L_E/c^2, the
luminosity suddenly rises from 0.3L_E to 2L_E, where L_E is the Eddington
luminosity. It decays after retaining high value for about 40 s. Our numerical
results can explain the variation amplitude and duration of the recurrent
outbursts observed in microquasar, GRS 1915+105. We show that the
multi-dimensional effects play an important role in the high-luminosity state.
In this state, the outflow is driven by the strong radiation force, and some
part of radiation energy dissipated inside the disk is swallowed by the black
hole due to the photon-trapping effects. This trapped luminosity is comparable
to the disk luminosity. We also calculate two more cases: one with a much
larger accretion rate than the critical value for the instability and the other
with the viscous stress tensor being proportional to the gas pressure only even
when the radiation pressure is dominant. We find no quasi-periodic light
variations in these cases. This confirms that the limit-cycle behavior found in
the simulations is caused by the disk instability.


title: The Very Early Gamma-ray Burst Afterglows Powered by Structured Jets

abstract:
  If X-ray flashes (XRFs) and X-ray rich Gamma-ray Bursts(XRRGs) have the same
origin with Gamma-ray Bursts (GRBs) but are viewed from larger angles of
structured jets, their early afterglows may differ from those of GRBs. When the
ultra-relativistic outflow interact with the surrounding medium, there are two
shocks formed, one is a forward shock, the other is a reverse shock. In this
paper we calculate numerically the early afterglow powered by uniform jet,
Gaussian jet and power-law jet in the forward-reverse shock scenario. A set of
differential equations are used to govern the dynamical evolution and
synchrotron self-Compton effect has been taken into account to calculate the
emission. In uniform jets, the very early afterglows of XRRGs and XRFs are
significantly lower than GRBs and the observed peak times of RS emission are
longer in interstellar medium environment. The RS components in XRRGs and XRFs
are difficult to be detected. But in stellar wind, the reduce of very early
flux and the delay of RS peak time are not so remarkable. In nonuniform
jet(Gaussian jet and power-law jet), where there are emission materials on the
line of sight, the very early light curve resembles isotropic-equivalent ejecta
in general although the RS flux decay index shows notable deviation if the RS
is relativistic(in stellar wind).


title: L_X-T Relation and Related Properties of Galaxy Clusters

abstract:
  An observational approach is presented to constrain the global structure and
evolution of the intracluster medium based on the ROSAT and ASCA distant
cluster sample. From statistical analysis of the gas density profile and the
connection to the LX-T relation under the beta-model, the scaled gas profile is
nearly universal for the outer region and the LX(>0.2r500) is tightly related
to the temperature through T^3 rather than T^2. On the other hand, a large
density scatter exists in the core region and there is clearly a deviation from
the self-similar scaling for clusters with a small core size. A direct link
between the core size and the radiative cooling timescale suggest that t_cool
is a parameter to control the gas structure and the appearance of small cores
in regular clusters may be much connected with the thermal evolution. We derive
the luminosity-ambient temperature (T') relation, assuming the universal
temperature profile to find the dispersion around the relation significantly
decreases: L_1keV is almost constant for a wide range of t_cool. We further
examined the LX-Tbeta and LX-T'beta relations and showed a trend that merging
clusters segregate from the regular clusters on the planes. A good correlation
between t_cool and the X-ray morphology on the L_1keV-t_cool/t_age plane leads
us to define three phases according to the different level of cooling, and draw
a phenomenological picture: after a cluster collapses and t_cool falls below
t_age, the core cools radiatively with quasi-hydrostatic balancing in the
gravitational potential, and the central density gradually becomes higher to
evolve from an outer-core-dominant cluster to inner-core-dominant cluster.


title: Is FLARE for Solar flare?

abstract:
  The Fermi Lab Liquid ARgon experiment, FLARE, a huge neutrino argon-liquid
project detector of 50 kt mass, might in a near future enlarge the neutrino
telescope accuracy revealing in detail solar, supernova, atmospheric as well as
largest solar flares neutrino. Indeed the solar energetic (E_p > 100 MeVs)
flare particles (protons, alpha) while scattering among themselves or hitting
the solar atmosphere must produce on sun prompt charged pions, whose decay (as
well as their sequent muon decays) into secondaries is source of a copious
solar neutrino "flare" (at tens or hundreds MeV energy). These brief (minutes)
neutrino "burst" at largest flare peak may overcome by three to five order of
magnitude the steady atmospheric neutrino noise on the Earth, possibly leading
to their emergence and detection above the thresholds. The largest prompt
"burst" solar neutrino flare may be detected in future FLARE neutrino detectors
both in electron and positron and possibly in its muon pair neutrino component.
Our estimate for the recent and exceptional October - November 2003 solar
flares and last January 20th 2005 exceptional flare might lead to a few events
for future FLARE or near unity for present Super-KamiokandeII. The neutrino
spectra may reflect the neutrino flavor oscillations and mixing in flight. In
neutrino detectors a surprising (correlated) muon appearance may occur while a
rarer tau appearance may even marginally take place. A comparison of the solar
neutrino flare signal with other neutrino foreground is estimated: it offer the
first opportunity for an independent road map to disentangle the neutrino
flavor puzzles, as well a prompt alarm system for dangerous solar flare
eruptions.


title: The stability of toroidal fields in stars

abstract:
  We present numerical models of hydromagnetic instabilities under the
conditions prevailing in a stably stratified, non-convective stellar interior,
and compare them with previous results of analytic work on instabilities in
purely toroidal fields. We confirm that an $m=1$ mode (`kink') is the dominant
instability in a toroidal field in which the field strength is proportional to
distance from the axis, such as the field formed by the winding up of a weak
field by differential rotation. We measure the growth rate of the instability
as a function of field strength and rotation rate $\Omega$, and investigate the
effects of a stabilising thermal stratification as well as magnetic and thermal
diffusion on the stability. Where comparison is computationally feasible, the
results agree with analytic predictions.


title: Reduced Wolf-Rayet Line Luminosities at Low Metallicity

abstract:
  New NTT/EMMI spectrophotometry of single WN2-5 stars in the Magellanic Clouds
are presented, from which HeII 4686 line luminosities have been derived, and
compared with observations of other Magellanic Cloud WR stars. SMC WN3-4 stars
possess line luminosities which are a factor of 4 times lower than LMC
counterparts, incorporating several binary SMC WN3-4 stars. Similar results are
found for WN5-6 stars, despite reduced statistics, incorporating observations
of single LMC WN5-9 stars. CIV 5808 line luminosities of carbon sequence WR
stars in the SMC and IC1613 (both WO subtypes) are a factor of 3 lower than LMC
WC stars from Mt Stromlo/DBS spectrophotometry, although similar results are
also obtained for the sole LMC WO star. We demonstrate how reduced line
luminosities at low metallicity follow naturally if WR winds are Z-dependent,
as recent results suggest. We apply mass loss-Z scalings to atmospheric non-LTE
models of Milky Way and LMC WR stars to predict the wind signatures of WR stars
in the metal-poor star forming WR galaxy IZw18. WN HeII 4686 line luminosities
are 7-20 times lower than in Z-rich counterparts of identical bolometric
luminosity, whilst WC CIV 5808 line luminosities are 3-6 times lower.
Significant He^+ Lyman continuum fluxes are predicted for Z-poor early-type WR
stars. Consequently, our results suggest the need for larger population of WR
stars in IZw18 than is presently assumed, particularly for WN stars,
potentially posing a severe challenge to evolutionary models at very low Z.
Finally, reduced wind strengths from WR stars at low Z impacts upon the
immediate circumstellar environment of long duration GRB afterglows,
particularly since the host galaxies of high-redshift GRBs tend to be Z-poor.


title: The MAGIC Telescope

abstract:
  MAGIC (Major Atmospheric Gamma Imaging Cherenkov telescope) is presently the
largest ground-based gamma ray telescope. MAGIC has been taking data regularly
since October 2004 at the Roque de los Muchachos Observatory on the island of
La Palma. In this paper the MAGIC telescope status, its performances and some
preliminary results on observed gamma ray sources are presented.


title:
Multiband photometric detection of a huge flare on the M9 dwarf 2MASSW
  J1707183+643933

abstract:
  We present simultaneous UV-G-R-I monitoring of 19 M dwarfs that revealed a
huge flare on the M9 dwarf 2MASSW J1707183+643933 with an amplitude in the UV
of at least 6 magnitudes. This is one of the strongest detections ever of an
optical flare on an M star and one of the first in an ultracool dwarf (UCD,
spectral types later than about M7). Four intermediate strength flares (Delta
m_UV < 4 mag) were found in this and three other targets. For the whole sample
we deduce a flare probability of 0.013 (rate of 0.018/hr), and 0.049 (0.090/hr)
for 2M1707+64 alone. Deviations of the flare emission from a blackbody is
consistent with strong Halpha line emission. We also confirm the previously
found rotation period for 2M1707+64 (Rockenfeller, Bailer-Jones & Mundt (2006),
http://arxiv.org/abs/astro-ph/0511614/) and determine it more precisely to be
3.619 +/- 0.015 hr.


title:
VLT-ISAAC 3-5 micron spectroscopy of embedded young low-mass stars. III.
  Intermediate-mass sources in Vela

abstract:
  We performed a spectroscopic survey toward five intermediate-mass class I
YSOs located in the Southern Vela molecular cloud in the L and M bands at
resolving powers 600-800 up to 10,000, using the Infrared Spectrometer and
Array Camera mounted on the VLT-ANTU. Lower mass companion objects were
observed simultaneously in both bands. Solid H2O at 3 micron is detected in all
sources, including the companion objects. CO ice at 4.67 micron is detected in
a few main targets and one companion object. One object (LLN 19) shows little
CO ice but strong gas-phase CO ro-vibrational lines in absorption. The CO ice
profiles are different from source to source. The amount of water ice and CO
ice trapped in a water-rich mantle may correlate with the flux ratio at 12 and
25 micron. The abundance of H2O-rich CO likely correlates with that of water
ice. A weak feature at 3.54 mu attributed to solid CH3OH and a broad feature
near 4.62 mu are observed toward LLN17, but not toward the other sources. The
derived abundances of solid CH3OH and OCN- are ~10% and ~1% of the H2O ice
abundance respectively. The H2O optical depths do not show an increase with
envelope mass, nor do they show lower values for the companion objects compared
with the main protostar. The line-of-sight CO ice abundance does not correlate
with the source bolometric luminosity. Comparison of the solid CO profile
toward LLN17, which shows an extremely broad CO ice feature, and that of its
lower mass companion at a few thousand AU, which exhibits a narrow profile,
together with the detection of OCN- toward LLN17 provide direct evidences for
local thermal processing of the ice.


title:
Simulating Cosmic Reionization at Large Scales I: the Geometry of
  Reionization

abstract:
  We present the first large-scale radiative transfer simulations of cosmic
reionization, in a simulation volume of (100/h Mpc)^3, while at the same time
capturing the dwarf galaxies which are primarily responsible for reionization.
We achieve this by combining the results from extremely large, cosmological,
N-body simulations with a new, fast and efficient code for 3D radiative
transfer, C^2-Ray. The resulting electron-scattering optical depth is in good
agreement with the first-year WMAP polarization data. We show that reionization
clearly proceeded in an inside-out fashion, with the high-density regions being
ionized earlier, on average, than the voids. Ionization histories of
smaller-size (5 to 10 comoving Mpc) subregions exibit a large scatter about the
mean and do not describe the global reionization history well. The minimum
reliable volume size for such predictions is ~30 Mpc. We derive the
power-spectra of the neutral, ionized and total gas density fields and show
that there is a significant boost of the density fluctuations in both the
neutral and the ionized components relative to the total at arcminute and
larger scales. We find two populations of HII regions according to their size,
numerous, mid-sized (~10 Mpc) regions and a few, rare, very large regions tens
of Mpc in size. We derive the statistical distributions of the ionized fraction
and ionized gas density at various scales and for the first time show that both
distributions are clearly non-Gaussian. (abridged)


title: Ultra High Energy Cosmic Rays from Sequestered X Bursts

abstract:
  Assuming that there is no GZK (Greisen-Zatsepin-Kuzmin) cut-off and that
super-GZK cosmic rays correlate with AGN (Active Galactic Nuclei) at
cosmological distances, it is speculated that a relic superheavy particle (X)
has its lifetime enhanced by sequestration in an extra dimension. This
sequestration is assumed to be partially liberated by proximity of merging
supermassive black holes in an AGN, temporarily but drastically reducing the
lifetime, thus stimulating an X burst. Based on sequestration of the decay
products of X, a speculative explanation of the observed $\gamma/N$ ratio is
proposed.


title:
Two-Dimensional Hydrodynamic Core-Collapse Supernova Simulations with
  Spectral Neutrino Transport II. Models for Different Progenitor Stars

abstract:
  1D and 2D supernova simulations for stars between 11 and 25 solar masses are
presented, making use of the Prometheus/Vertex neutrino-hydrodynamics code,
which employs a full spectral treatment of the neutrino transport.
Multi-dimensional transport aspects are treated by the ``ray-by-ray plus''
approximation described in Paper I. Our set of models includes a 2D calculation
for a 15 solar mass star whose iron core is assumed to rotate rigidly with an
angular frequency of 0.5 rad/s before collapse. No important differences were
found depending on whether random seed perturbations for triggering convection
are included already during core collapse, or whether they are imposed on a 1D
collapse model shortly after bounce. Convection below the neutrinosphere sets
in about 40 ms p.b. at a density above 10**12 g/cm^3 in all 2D models, and
encompasses a layer of growing mass as time goes on. It leads to a more
extended proto-neutron star structure with accelerated lepton number and energy
loss and significantly higher muon and tau neutrino luminosities, but reduced
mean energies of the radiated neutrinos, at times later than ~100 ms p.b. In
case of an 11.2 solar mass star we find that low (l = 1,2) convective modes
cause a probably rather weak explosion by the convectively supported
neutrino-heating mechanism after ~150 ms p.b. when the 2D simulation is
performed with a full 180 degree grid, whereas the same simulation with 90
degree wedge fails to explode like all other models. This sensitivity
demonstrates the proximity of our 2D models to the borderline between success
and failure, and stresses the need of simulations in 3D, ultimately without the
axis singularity of a polar grid. (abridged)


title: SS 433 : a phenomenon imitating a Wolf-Rayet star

abstract:
  We present mid-infrared (2-12 micron) spectra of the microquasar SS 433
obtained with the Infrared Space Observatory (spectroscopic mode of ISOPHOT and
ISOCAM). We compare them to the spectra of four Wolf-Rayet stars: WR78, WR134,
WR136, and WR147 in the same wavelength range. The mid-infrared spectrum of SS
433 mainly shows HI and HeI emission lines and is very similar to the spectrum
of WR147, a WN8(h)+B0.5V binary. The 2-12 micron continuum emission of SS 433
corresponds to optically thin and partially optically thick free-free emission,
from which we calculate a mass loss rate of 2-3 x 10^{-4} Msun/yr if the wind
is homogeneous and a third of these values if it is clumped. This is consistent
with a strong stellar wind from a WN star. However, following recent studies
concluding that the mass donor star of SS 433 is not a Wolf-Rayet star, we
propose that this strong wind out flows from a geometrically thick envelope of
material that surrounds the compact object like a stellar atmosphere, imitating
the Wolf-Rayet phenomenon. This wind could also wrap the mass donor star, and
at larger distances (~ 40 AU), it might form a dust envelope from which the
thermal emission, detected with ISOPHOT at 25 micron and 60 micron, would
originate. This wind also probably feeds the material that is ejected in the
orbital plane of the binary system and that forms the equatorial outflow
detected in radio at distances > 100 AU.


title: 10 New Very Low Mass Close Binaries Resolved in the Visible

abstract:
  We present preliminary results from the first part of the LuckyCam late
M-dwarf binarity survey. We survey a sample of 48 nearby ($<$40 pc) and red
(M5-M9) stars with the novel high angular resolution visible light imaging
technique Lucky Imaging, in only 8 hours of 2.5m telescope time. We discover 10
new binaries; although the survey is sensitive to brown dwarf companions none
are detected. The orbital radius distribution of the newly discovered binaries
broadly matches that of previous detections by other groups, although we do
discover one wide binary at ~40AU.


title: Acceleration of low energy charged particles by gravitational waves

abstract:
  The acceleration of charged particles in the presence of a magnetic field and
gravitational waves is under consideration. It is shown that the weak
gravitational waves can cause the acceleration of low energy particles under
appropriate conditions. Such conditions may be satisfied close to the source of
the gravitational waves if the magnetized plasma is in a turbulent state.


title: Star-burst regions in the LMC

abstract:
  Aims. Filamentary structures of early type stars are found to be a common
feature of the Magellanic Clouds formed at an age of about 0.9-2*10^8 yr. As we
go to younger ages these large structures appear fragmented and sooner or later
form young clusters and associations. In the optical domain we have detected 56
such large structures of young objects, known as stellar complexes in the LMC
for which we give coordinates and dimensions. We also investigate star
formation activity and evolution of these stellar complexes and define the term
"starburst region". Methods. IR properties of these regions have been
investigated using IRAS data. A colour-magnitude diagram (CMD) and a two-colour
diagram from IRAS data of these regions ware compared with observations of
starburst galaxies and cross-matching with HII regions and SNRs was made .
Radio emission maps at 8.6-GHz and the CO (1 to 0) line were also cross
correlated with the map of the stellar complexes. Results. It has been found
that nearly 1/3 of the stellar complexes are extremely active resembling the IR
behaviour of starburst galaxies and HII regions. These stellar complexes
illustrating such properties are called here "starburst regions". They host an
increased number of HII regions and SNRs. The main starburst tracers are their
IR luminosity (F60 well above 5.4 Jy) and the 8.6-GHz radio emission. Finally
the evolution of all stellar complexes is discussed based on the CO emission.


title: Constraints on Alternatives to Supermassive Black Holes

abstract:
  Observations of the centers of galaxies continue to evolve, and it is useful
to take a fresh look at the constraints that exist on alternatives to
supermassive black holes at their centers. We discuss constraints complementary
to those of Maoz (1998) and demonstrate that an extremely wide range of other
possibilities can be excluded. In particular, we present the new argument that
for the velocity dispersions inferred for many galactic nuclei, even binaries
made of point masses cannot stave off core collapse because hard binaries are
so tight that they merge via emission of gravitational radiation before they
can engage in three-body or four-body interactions. We also show that under
these conditions core collapse leads inevitably to runaway growth of a central
black hole with a significant fraction of the initial mass, regardless of the
masses of the individual stars. For clusters of noninteracting low-mass objects
(from low-mass stars to elementary particles), relaxation of stars and compact
objects that pass inside the dark region will be accelerated by interactions
with the dark mass. If the dark region is instead a self-supported object such
as a fermion ball, then if stellar-mass black holes exist they will collide
with the object, settle, and consume it. The net result is that the keyhole
through which alternatives to supermassive black holes must pass is
substantially smaller and more contrived than it was even a few years ago.


title: Scale-invariant Perturbations from Chaotic Inflation

abstract:
  Vacuum fluctuations in the inflaton field driving chaotic inflation with a
quadratic potential give a red spectrum of primordial density perturbations,
n=0.97. However angular fluctuations in an O(N)-symmetric quadratic potential
have a very nearly scale-invariant spectrum, n=0.9998. We investigate the
possibility that these isocurvature field perturbations could give the dominant
contribution to the primordial density perturbation after inflation.


title:
On the "canonical behaviour" of the X-ray afterglows of the Gamma Ray
  Bursts observed with Swift's XRT

abstract:
  The "canonical behaviour" of the early X-ray afterglows of long-duration
Gamma-Ray Bursts (GRBs) --observed by the X-Ray Telescope of the SWIFT
satellite-- is precisely the one predicted by the Cannonball model of GRBs.


title: First-order formalism and dark energy

abstract:
  This work deals with cosmological models driven by real scalar field,
described by standard dynamics in generic spherical, flat, and hyperbolic
geometries. We introduce a first-order formalism, which shows how to relate the
potential that specifies the scalar field model to Hubble's parameter in a
simple and direct manner. Extensions to tachyonic dynamics, and to two or more
real scalar fields are also presented.


title:
Planets in Stellar Clusters Extensive Search. IV. A detection of a
  possible transiting planet candidate in the open cluster NGC 2158

abstract:
  We have undertaken a long-term project, Planets in Stellar Clusters Extensive
Search (PISCES), to search for transiting planets in open clusters. In this
paper we present the results for NGC 2158, an intermediate age, populous
cluster. We have monitored the cluster for over 260 hours, spread over 59
nights. We have detected one candidate transiting low luminosity object, with
eclipse depth of 3.7% in the R-band. If the host star is a member of the
cluster, the eclipse depth is consistent with a 1.7 R_J object. Cluster
membership of the host is supported by its location on the cluster main
sequence (MS) and its close proximity to the cluster center (2'). We have
discovered two other stars exhibiting low-amplitude (4-5%) transits, V64 and
V70, but they are most likely blends or field stars. Given the photometric
precision and temporal coverage of our observations, and current best estimates
for the frequency and radii of short-period planets, the expected number of
detectable transiting planets in our sample is 0.13. We have observed four
outbursts for the candidate cataclysmic variable V57. We have discovered 40 new
variable stars in the cluster, bringing the total number of identified
variables to 97, and present for them high precision light curves, spanning 13
months.


title:
MHD simulations of radiative jets from young stellar objects: Halpha
  emission

abstract:
  We study the H$\alpha$ emission from jets using two-dimensional
axisymmetrical simulations. We compare the emission obtained from hydrodynamic
(HD) simulations with that obtained from magnetohydrodynamics (MHD)
simulations. The magnetic field is supposed to be present in the jet only, and
with a toroidal configuration. The simulations have time-dependent ejection
velocities and different intensities for the initial magnetic field. The
results show an increase in the H$\alpha$ emission along the jet for the
magnetized cases with respect to the HD case. The increase in the emission is
due to a better collimation of the jet in the MHD case, and to a small increase
in the shock velocity. These results could have important implications for the
interpretation of the observations of jets from young stellar objects.


title:
Kinemetry: a generalisation of photometry to the higher moments of the
  line-of-sight velocity distribution

abstract:
  We present a generalisation of surface photometry to the higher-order moments
of the line-of-sight velocity distribution of galaxies observed with
integral-field spectrographs. The generalisation follows the approach of
surface photometry by determining the best fitting ellipses along which the
profiles of the moments can be extracted and analysed by means of harmonic
expansion. The assumption for the odd moments (e.g. mean velocity) is that the
profile along an ellipse satisfies a simple cosine law. The assumption for the
even moments (e.g velocity dispersion) is that the profile is constant, as it
is used in surface photometry. We find that velocity profiles extracted along
ellipses of early-type galaxies are well represented by the simple cosine law
(with 2% accuracy), while possible deviations are carried in the fifth harmonic
term which is sensitive to the existence of multiple kinematic components, and
has some analogy to the shape parameter of photometry. We compare the
properties of the kinematic and photometric ellipses and find that they are
often very similar. Finally, we offer a characterisation of the main velocity
structures based only on the kinemetric parameters which can be used to
quantify the features in velocity maps (abridged).


title:
Acoustic oscillations in the SDSS DR4 Luminous Red Galaxy sample power
  spectrum

abstract:
  We calculate the redshift-space power spectrum of the Sloan Digital Sky
Survey (SDSS) Data Release 4 (DR4) Luminous Red Galaxy (LRG) sample, finding
evidence for a full series of acoustic features down to the scales of \sim 0.2
hMpc^{-1}. This corresponds up to the 7th peak in the CMB angular power
spectrum. The acoustic scale derived, (105.4 \pm 2.3) h^{-1}Mpc, agrees very
well with the ``concordance'' model prediction and also with the one determined
via the analysis of the spatial two-point correlation function by Eisenstein et
al. (2005). The models with baryonic features are favored by 3.3 \sigma over
their ``smoothed-out'' counterparts without any oscillatory behavior.


title:
Spatially-resolved mid-infrared spectroscopy of NGC 1068: the nature and
  distribution of the nuclear material

abstract:
  We present spatially-resolved, near-diffraction-limited 10 micron spectra of
the nucleus of the Seyfert 2 galaxy NGC 1068, obtained with Michelle, the
mid-IR imager and spectrometer on the 8.1 m Gemini North telescope. The spectra
cover the nucleus and the central 6.0" x 0.4" of the ionization cones at a
spatial resolution of approximately 0.4" (approx. 30 parsecs). The spectra
extracted in 0.4" steps along the slit reveal striking variations in continuum
slope, silicate feature profile and depth, and fine structure line fluxes on
subarcsecond scales, illustrating in unprecedented detail the complexity of the
circumnuclear regions of this galaxy at mid-IR wavelengths. A comparison of
photometry in various apertures reveals two distinct components: a compact
(radius <15 pc), bright source within the central 0.4" x 0.4" and extended,
lower brightness emission. We identify the compact source with the AGN
obscuring torus, and the diffuse component with the AGN-heated dust in the
ionization cones. While the torus emission dominates the flux observed in the
near-IR, the mid-IR flux measured with apertures larger than about 1" is
dominated instead by the dust emission from the ionization cones. Many previous
attempts to determine the torus spectral energy distribution are thus likely to
be significantly affected by contamination from the extended emission. The
observed spectrum of the compact source is compared with clumpy torus models,
which require most of the mid-IR emitting clouds to be located within a few
parsecs of the central engine. We also present a UKIRT/CGS4 5 micron spectrum
covering the R(0) -- R(4) lines of the fundamental vibration-rotation band of
12CO. None of these lines was detected, and we discuss these non-detections in
terms of the filling factor and composition of the nuclear clouds. (Abridged)


title: Detecting Faint Galaxies by Stacking at 24 micron

abstract:
  We stack Spitzer 24 micron images for ~7000 galaxies with 0.1<z<1 in the
Chandra Deep Field South to probe the thermal dust emission in low-luminosity
galaxies over this redshift range. Through stacking, we can detect mean 24
micron fluxes that are more than an order of magnitude below the individual
detection limit. We find that the correlations for low and moderate luminosity
galaxies between the average L_IR/L_UV and rest-frame B-band luminosity, and
between the star formation rate (SFR) and L_IR/L_UV, are similar to those in
the local Universe. This verifies that oft-used assumption in deep UV/optical
surveys that the dust obscuration-SFR relation for galaxies with SFR < 20 solar
mass per year varies little with epoch. We have used this relation to derive
the cosmic IR luminosity density from z=1 to z=0.1. The results also
demonstrate directly that little of the bolometric luminosity of the galaxy
population arises from the faint end of the luminosity function, indicating a
relatively flat faint-end slope of the IR luminosity function with a power law
index of 1.2+-0.3.


title: How unlikely is a doomsday catastrophe?

abstract:
  Numerous Earth-destroying doomsday scenarios have recently been analyzed,
including breakdown of a metastable vacuum state and planetary destruction
triggered by a "strangelet'' or microscopic black hole. We point out that many
previous bounds on their frequency give a false sense of security: one cannot
infer that such events are rare from the the fact that Earth has survived for
so long, because observers are by definition in places lucky enough to have
avoided destruction. We derive a new upper bound of one per 10^9 years (99.9%
c.l.) on the exogenous terminal catastrophe rate that is free of such selection
bias, using planetary age distributions and the relatively late formation time
of Earth.


title:
First Resolved Images of the Mira AB Symbiotic Binary at Centimeter
  Wavelengths

abstract:
  We report the first spatially resolved radio continuum measurements of the
Mira AB symbiotic binary system, based on observations obtained with the Very
Large Array (VLA). This is the first time that a symbiotic binary has been
resolved unambiguously at centimeter wavelengths. We describe the results of
VLA monitoring of both stars over a ten month period, together with constraints
on their individual spectral energy distributions, variability, and radio
emission mechanisms. The emission from Mira A is consistent with originating
from a radio photosphere, while the emission from Mira B appears best explained
as free-free emission from an ionized circumstellar region ~(1-10)x10**13 cm in
radius.


title:
UV pumping of hyperfine transitions in the light elements, with
  application to 21-cm hydrogen and 92-cm deuterium lines from the early
  universe

abstract:
  We present new analytic calculations of the coupling between ultraviolet
resonance photons and the population of the hyperfine states in the light
elements (H, D, He3+) which include several previously neglected physical
processes. Among these are the backreaction of resonant scattering on the
pumping radiation, the scattering of Ly_beta photons and the effect of local
departure from pure Hubble flow. The application of the new treatment to the
redshifted hydrogen 21 and deuterium 92 cm lines from the high-redshift
universe results in an amplitude correction of up to an order of magnitude. We
further show that the standard assumption that ultraviolet pumping drives the
spin temperature towards the kinetic temperature does not hold for deuterium,
whose spin temperature is generally negative.


title:
Survey for Transiting Extrasolar Planets in Stellar Systems: III. A
  Limit on the Fraction of Stars with Planets in the Open Cluster NGC 1245

abstract:
  We analyze a 19-night photometric search for transiting extrasolar planets in
the open cluster NGC 1245. An automated transit search algorithm with
quantitative selection criteria finds six transit candidates; none are bona
fide planetary transits. We characterize the survey detection probability via
Monte Carlo injection and recovery of realistic limb-darkened transits. We use
this to derive upper limits on the fraction of cluster members with close-in
Jupiter-radii, RJ, companions. We carefully analyze the random and systematic
errors of the calculation. For similar photometric noise and weather properties
as this survey, observing NGC 1245 twice as long results in a tighter
constraint on "Hot Jupiter", HJ, companions than observing an additional
cluster of similar richness as NGC 1245 for the same length of time as this
survey. This survey observed ~870 cluster members. If 1% of stars have 1.5 RJ
HJ companions, we expect to detect one planet for every 5000 dwarf stars
observed for a month. To reach a ~2% upper limit on the fraction of stars with
1.5 RJ HJ companions, we conclude a total sample size of ~7400 dwarf stars
observed for at least a month will be needed. Results for 1.0 RJ companions,
without substantial improvement in the photometric precision, will require a
small factor larger sample size.


title:
The Impact of Galaxy Formation on the Sunyaev-Zeldovich Effect of Galaxy
  Clusters

abstract:
  We study the effects of galaxy formation on the Sunyaev-Zel'dovich effect
(SZE) observable-mass relations using high-resolution cosmological simulations.
The simulations of eleven individual clusters spanning a decade in mass are
performed with the shock-capturing Eulerian adaptive mesh refinement
N-body+gasdynamics ART code. To assess the impact of galaxy formation, we
compare two sets of simulations performed in an adiabatic regime and those with
several physical processes critical to various aspects of galaxy formation:
radiative cooling, star formation, stellar feedback and metal enrichment. We
show that a SZE signal integrated to a sufficiently large fraction of cluster
volume correlates strongly with its enclosed mass, independent of details of
gas physics and dynamical state of the cluster. The slope and redshift
evolution of the SZE flux-mass relation are also insensitive to processes of
galaxy formation and are well characterized by a simple self-similar cluster
model. Its normalization, on the other hand, is significantly affected by gas
cooling and associated star formation. Our simulations show that inclusion of
these processes suppresses the normalization by ~30-40%. The effect is due to a
decrease in gas mass fraction, which is offset slightly by an increase in gas
mass-weighted temperature. Gas cooling and star formation also cause an
increase in total mass and modify the normalization by a few percent. Finally,
the comparison with recent observations of the SZE scaling relations highlights
the importance of galaxy formation in theoretical modelling of clusters and
shows that current generation of simulations produce clusters with gross
properties quite similar to their observed counterparts.


title: Discovery of extended emission around the pulsar B0355+54

abstract:
  PSR B0355+54 is one of the handful of pulsars that has been observed with
both Chandra and XMM-Newton. The analysis of the archival data has revealed the
pulsar and a ~30 arcsec compact nebula surrounding it. XMM-Newton also has
detected a trail which extends ~6 arcmin and similar to the compact nebula is
also counter-aligned with the proper motion of the pulsar. The spectrum of both
the pulsar and the extended emission are well described by an absorbed
power-law model. The measured flux corresponds to an efficiency of converting
the spin-down luminosity into X-rays in the 2-10 keV band of ~0.01% and ~1% for
the pulsar and the extended emission, respectively. From the XMM-Newton data we
have detected pulsations at the expected radio period. The energetic and the
extent of the extended emission can be explained by a Bow-shock formed by the
motion of the pulsar through the interstellar medium.


title: An excess of damped Lyman alpha galaxies near QSOs

abstract:
  We present a sample of 33 damped Lyman alpha systems (DLAs) discovered in the
Sloan Digital Sky Survey (SDSS) whose absorption redshifts (z_abs) are within
6000 km/s of the QSO's systemic redshift (z_sys). Our sample is based on 731
2.5 < z_sys < 4.5 non-broad-absorption-line (non-BAL) QSOs from Data Release 3
(DR3) of the SDSS. We estimate that our search is ~100 % complete for absorbers
with N(HI) >= 2e20 cm^-2. The derived number density of DLAs per unit redshift,
n(z), within v < 6000 km/s is higher (3.5 sigma significance) by almost a
factor of 2 than that of intervening absorbers observed in the SDSS DR3, i.e.
there is evidence for an overdensity of galaxies near the QSOs. This provides a
physical motivation for excluding DLAs at small velocity separations in surveys
of intervening 'field' DLAs. In addition, we find that the overdensity of
proximate DLAs is independent of the radio-loudness of the QSO, consistent with
the environments of radio-loud and radio-quiet QSOs being similar.


title: On The Nature of the Compact Dark Mass at the Galactic Center

abstract:
  We consider a model in which Sgr A*, the 3.5x10^6 M_sun supermassive black
hole candidate at the Galactic Center, is a compact object with a surface.
Given the very low quiescent luminosity of Sgr A* in the near infrared, the
existence of a hard surface, even in the limit in which the radius approaches
the horizon, places severe constraints upon the steady mass accretion rate in
the source, requiring dM/dt < 10^-12 M_sun/yr. This limit is well below the
minimum accretion rate needed to power the observed submillimeter luminosity of
Sgr A*. We thus argue that Sgr A* does not have a surface, i.e., it must have
an event horizon. The argument could be made more restrictive by an order of
magnitude with microarcsecond resolution imaging, e.g., with submillimeter
VLBI.


title:
Prospects of LIGO for constraining inclination of merging compact
  binaries associated with three-dimensionally localized short-hard GRBs

abstract:
  We study prospects of a method to constrain the inclination of a coalescing
compact binary by detecting its gravitational waves associated with a
three-dimensionally localized (direction and distance) short-hard gamma-ray
burst. We take advantage of a synergy of these two observations, and our method
can be applied even with a single interferometer. For a nearly face-on binary
the inclination angle $I$ can be constrained in the range 1-1/SNR < cosI \le 1
(SNR: the signal to noise ratio of gravitational wave detection), provided that
the error of the distance estimation is negligible. This method would help us
to study properties of the short-hard bursts, including potentially collimated
jet-like structures as indicated by recent observation.


title:
Combining rotation curves and gravitational lensing: How to measure the
  equation of state of dark matter in the galactic halo

abstract:
  We argue that combined observations of galaxy rotation curves and
gravitational lensing not only allow the deduction of a galaxy's mass profile,
but also yield information about the pressure in the galactic fluid. We
quantify this statement by enhancing the standard formalism for rotation curve
and lensing measurements to a first post-Newtonian approximation. This enhanced
formalism is compatible with currently employed and established data analysis
techniques, and can in principle be used to reinterpret existing data in a more
general context. The resulting density and pressure profiles from this new
approach can be used to constrain the equation of state of the galactic fluid,
and therefore might shed new light on the persistent question of the nature of
dark matter.


title:
The nature of turbulence in OMC1 at the star forming scale: observations
  and simulations

abstract:
  Aim: To study turbulence in the Orion Molecular Cloud (OMC1) by comparing
observed and simulated characteristics of the gas motions.
  Method: Using a dataset of vibrationally excited H2 emission in OMC1
containing radial velocity and brightness which covers scales from 70AU to
30000AU, we present the transversal structure functions and the scaling of the
structure functions with their order. These are compared with the predictions
of two-dimensional projections of simulations of supersonic hydrodynamic
turbulence.
  Results: The structure functions of OMC1 are not well represented by power
laws, but show clear deviations below 2000AU. However, using the technique of
extended self-similarity, power laws are recovered at scales down to 160AU. The
scaling of the higher order structure functions with order deviates from the
standard scaling for supersonic turbulence. This is explained as a selection
effect of preferentially observing the shocked part of the gas and the scaling
can be reproduced using line-of-sight integrated velocity data from subsets of
supersonic turbulence simulations. These subsets select regions of strong flow
convergence and high density associated with shock structure. Deviations of the
structure functions in OMC1 from power laws cannot however be reproduced in
simulations and remains an outstanding issue.


title: IRS spectra of two ultraluminous infrared galaxies at z=1.3

abstract:
  We present low-resolution (64 < R < 124) mid-infrared (8--38 micron)
Spitzer/IRS spectra of two z~1.3 ultraluminous infrared galaxies (LFIR~10^13)
discovered in a Spitzer/MIPS survey of the Bootes field of the NOAO Deep
Wide-Field Survey (NDWFS). MIPS J142824.0+352619 is a bright 160 micron source
with a large infrared-to-optical flux density ratio and a possible lensing
amplification of <~10. The 6.2, 7.7, 11.3, and 12.8 micron PAH emission bands
in its IRS spectrum indicate a redshift of z~1.3. The large equivalent width of
the 6.2 micron PAH feature indicates that at least 50% of the mid-infrared
energy is generated in a starburst, an interpretation that is supported by a
large [NeII]/[NeIII] ratio and a low upper limit on the X-ray luminosity. SST24
J142827.19+354127.71 has the brightest 24 micron flux (10.55 mJy) among
optically faint (R > 20) galaxies in the NDWFS. Its mid-infrared spectrum lacks
emission features, but the broad 9.7 micron silicate absorption band places
this source at z~1.3. Given this redshift, SST24 J142827.19+354127.71 has among
the largest rest-frame 5 micron luminosities known. The similarity of its SED
to those of known AGN-dominated ULIRGs and its lack of either PAH features or
large amounts of cool dust indicate that the powerful mid-infrared emission is
dominated by an active nucleus rather than a starburst. Our results illustrate
the power of the IRS in identifying massive galaxies in the ``redshift desert''
and in discerning their power sources. Because they are bright, MIPS
J142824.0+352619 (pending future observations to constrain its lensing
amplification) and SST24 J142827.19+354127.71 are useful z>1 templates of a
high luminosity starburst and AGN, respectively.


title:
Self-similar pressure oscillations in neutron star envelopes as probes
  of neutron star structure

abstract:
  We study eigenmodes of acoustic oscillations of high multipolarity l ~ 100 -
1000 and high frequency (~100 kHz), localized in neutron star envelopes. We
show that the oscillation problem is self-similar. Once the oscillation
spectrum is calculated for a given equation of state (EOS) in the envelope and
given stellar mass M and radius R, it can be rescaled to a star with any M and
R (but the same EOS in the envelope). For l>300 the modes can be subdivided
into the outer and inner ones. The outer modes are mainly localized in the
outer envelope. The inner modes are mostly localized near the neutron drip
point, being associated with the softening of the EOS after the neutron drip.
We calculate oscillation spectra for the EOSs of cold-catalyzed and accreted
matter and show that the spectra of the inner modes are essentially different.
A detection and identification of high-frequency pressure modes would allow one
to infer M and R and determine also the EOS in the envelope (accreted or
ground-state) providing thus a new and simple method to explore the main
parameters and internal structure of neutron stars.


title:
Anisotropy of the cosmic gamma-ray background from dark matter
  annihilation

abstract:
  High-energy photons from dark matter annihilation contribute to the cosmic
gamma-ray background (CGB). Since dark matter particles are weakly interacting,
annihilation can happen only in high density regions such as dark matter halos.
The precise shape of the energy spectrum of CGB depends on the nature of dark
matter particles, as well as the cosmological evolution of dark matter halos.
In order to discriminate between the signals from dark matter annihilation and
other astrophysical sources, however, the information from the energy spectrum
may not be sufficient. We show that dark matter annihilation also produces a
characteristic anisotropy of the CGB, which provides a powerful tool for
testing the origin. We develop the formalism based on a halo model approach to
calculate the three-dimensional power spectrum of dark matter clumping, which
determines the power spectrum of annihilation signals. We show that the
sensitivity of future gamma-ray detectors such as GLAST should allow us to
measure the angular power spectrum of CGB anisotropy, if dark matter particles
are supersymmetric neutralinos and they account for most of the observed mean
intensity of CGB in GeV region. On the other hand, if dark matter has a
relatively small mass, and accounts for most of the CGB in MeV region, then the
future Advanced Compton Telescope should be able to measure the anisotropy in
MeV region. As the intensity of photons from annihilation is proportional to
the density squared, we show that the predicted shape of the angular power
spectrum of gamma rays from dark matter annihilation is different from that due
to other astrophysical sources such as blazars. Therefore, the angular power
spectrum of the CGB provides a smoking-gun signature of dark matter
annihilation.


title: Weak Gravitational Lensing of High-Redshift 21 cm Power Spectra

abstract:
  We describe the effects of weak gravitational lensing by cosmological large
scale structure on the diffuse emission of 21 centimeter radiation from neutral
hydrogen at high redshifts during the era of reionization. The ability to
observe radial information through the frequency, and thus three-dimensional
regions of the background radiation at different redshifts, suggests that 21 cm
studies may provide a useful context for studying weak lensing effects. We
focus on the gravitational lensing effects on both the angular power spectra
and the intrinsic, three-dimensional power spectra. We present a new approach
for calculating the weak lensing signature based on integrating differential
Fourier-space shells of the deflection field and approximating the
magnification matrix. This method is applied to reionization models of the 21
cm spectra up to small angular scales over a range in redshift. The effect on
the angular power spectrum is typically < 1% on small angular scales, and very
small on scales corresponding to the feature imprinted by reionization bubbles,
due to the near-scale invariance of the angular power spectrum of the 21 cm
signal on these scales. We describe the expected effect of weak lensing on
three-dimensional 21 cm power spectra, and show that lensing creates aspherical
perturbations to the intrinsic power spectrum which depend on the polar angle
of the wavevector. The effect on the 3D power spectrum is < 1% on scales k <
0.1 h/Mpc, but can be > 1% for highly inclined modes for k > 1 h/Mpc. The
angular variation of the lensing effect on these scales is well described by a
quartic polynomial in the cosine of the polar angle. The detection of the
gravitational lensing effects on 21 cm power spectra will require very
sensitive, high resolution observations by future low-frequency radio arrays.


title:
Abundances of refractory elements in the atmospheres of stars with
  extrasolar planets

abstract:
  This work presents a uniform and homogeneous study of chemical abundances of
refractory elements in 101 stars with and 94 without known planetary
companions. We carry out an in-depth investigation of the abundances of Si, Ca,
Sc, Ti, V, Cr, Mn, Co, Ni, Na, Mg and Al. The new comparison sample, spanning
the metallicity range -0.70< [Fe/H]< 0.50, fills the gap that previously
existed, mainly at high metallicities, in the number of stars without known
planets. We used an enlarged set of data including new observations, especially
for the field ``single'' comparison stars. The line list previously studied by
other authors was improved: on average we analysed 90 spectral lines in every
spectrum and carefully measured more than 16600 equivalent widths (EW) to
calculate the abundances. We investigate possible differences between the
chemical abundances of the two groups of stars, both with and without planets.
The results are globally comparable to those obtained by other authors, and in
most cases the abundance trends of planet-host stars are very similar to those
of the comparison sample. This work represents a step towards the comprehension
of recently discovered planetary systems. These results could also be useful
for verifying galactic models at high metallicities and consequently improve
our knowledge of stellar nucleosynthesis and galactic chemical evolution.


title:
MIMAC-He3 : A Micro-TPC Matrix of Chambers of He3 for direct detection
  of Wimps

abstract:
  The project of a micro-TPC matrix of chambers of \hetrois for direct
detection of non-baryonic dark matter is presented. The privileged properties
of He3 are highlighted. The double detection (ionization - projection of
tracks) is explained and its rejection evaluated. The potentialities of
MIMAC-He3 for supersymmetric dark matter search are discussed.


title:
Abundance ratios of volatile vs. refractory elements in
  planet-harbouring stars: hints of pollution?

abstract:
  We present the [X/H] trends as function of the elemental condensation
temperature Tc in 88 planet host stars and in a volume-limited comparison
sample of 33 dwarfs without detected planetary companions. We gathered
homogeneous abundance results for many volatile and refractory elements
spanning a wide range of Tc, from a few dozens to several hundreds kelvin. We
investigate possible anomalous trends of planet hosts with respect to
comparison sample stars in order to detect evidence of possible pollution
events. No significant differences are found in the behaviour of stars with and
without planets. This result is in agreement with a ``primordial'' origin of
the metal excess in planet host stars. However, a subgroup of 5 planet host and
1 comparison sample stars stands out for having particularly high [X/H] vs. Tc
slopes.


title: Condensation temperature trends among stars with planets

abstract:
  Results from detailed spectroscopic analyses of stars hosting massive planets
are employed to search for trends between abundances and condensation
temperatures. The elements C, S, Na, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni and
Zn are included in the analysis of 64 stars with planets and 33 comparison
stars. No significant trends are evident in the data. This null result suggests
that accretion of rocky material onto the photospheres of stars with planets is
not the primary explanation for their high metallicities. However, the
differences between the solar photospheric and meteoritic abundances do display
a weak but significant trend with condensation temperature. This suggests that
the metallicity of the sun's envelope has been enriched relative to its
interior by about 0.07 dex.


title: The Distance to the Perseus Spiral Arm in the Milky Way

abstract:
  We have measured the distance to the massive star-forming region W3OH in the
Perseus spiral arm of the Milky Way to be 1.95 $\pm$ 0.04 kilo-parsecs
($5.86\times10^{16}$ km). This distance was determined by triangulation, with
the Earth's orbit as one segment of a triangle, using the Very Long Baseline
Array. This resolves a long-standing problem of a factor of two discrepancy
between different techniques to determine distances. The reason for the
discrepancy is that this portion of the Perseus arm has anomalous motions. The
orientation of the anomalous motion agrees with spiral density-wave theory, but
the magnitude is somewhat larger than most models predict.


title:
Cosmo-dynamics and dark energy with non-linear equation of state: a
  quadratic model

abstract:
  We investigate the general relativistic dynamics of Robertson-Walker models
with a non-linear equation of state (EoS), focusing on the quadratic case P =
P_0 + \alpha \rho + \beta \rho^2. This may be taken to represent the Taylor
expansion of any arbitrary barotropic EoS, P(\rho). With the right combination
of P_0, \alpha and \beta, it serves as a simple phenomenological model for dark
energy, or even unified dark matter. Indeed we show that this simple model for
the EoS can produce a large variety of qualitatively different dynamical
behaviors that we classify using dynamical systems theory. An almost universal
feature is that accelerated expansion phases are mostly natural for these
non-linear EoS's. These are often asymptotically de Sitter thanks to the
appearance of an effective cosmological constant. Other interesting
possibilities that arise from the quadratic EoS are closed models that can
oscillate with no singularity, models that bounce between infinite
contraction/expansion and models which evolve from a phantom phase,
asymptotically approaching a de Sitter phase instead of evolving to a "Big
Rip". In a second paper we investigate the effects of the quadratic EoS in
inhomogeneous and anisotropic models, focusing in particular on singularities.


title:
IRAS 16293-2422: Evidence for Infall onto a Counter-Rotating
  Protostellar Accretion Disk

abstract:
  We report high spatial resolution VLA observations of the low-mass
star-forming region IRAS 16293-2422 using four molecular probes: ethyl cyanide
(CH$_3$CH$_2$CN), methyl formate (CH$_3$OCHO), formic acid (HCOOH), and the
ground vibrational state of silicon monoxide (SiO). Ethyl cyanide emiss ion has
a spatial scale of $\sim20''$ and encompasses binary cores A and B as
determined by continuum emission peaks. Surrounded by formic acid emission,
methyl formate emission has a spatial scale of $\sim6''$and is confined to core
B. SiO emission shows two velocity components with spatial scales less than
2$''$ that map $\sim2''$ northeast of the A and B symmetry axis. The redshifted
SiO is $\sim2''$ northwest of blueshifted SiO along a position angle of
$\sim135^o$ which is approximately parallel to the A and B symmetry axis. We
interpret the spatial position offset in red and blueshifted SiO emission as
due to rotation of a protostellar accretion disk and we derive $\sim$1.4
M$_{\odot}$ interior to the SiO emission. In the same vicinity, Mundy et al.
(1986) also concluded rotation of a nearly edge-on disk from OVRO observations
of much stronger and ubiquitous $^{13}$CO emission but the direction of
rotation is opposite to the SiO emission findings. Taken together, SiO and
$^{13}$CO data suggest evidence for a counter-rotating disk. Moreover, archival
BIMA array $^{12}$CO data show an inverse P Cygni profile with the strongest
absorption in close proximity to the SiO emission, indicating unambiguous
material infall toward the counter-rotating protostellar disk at a new source
location within the IRAS 16293-2422 complex. The details of these observations
and our interpretations are discussed.


title: Water maser motions in W3(OH) and a determination of its distance

abstract:
  We report phase-referencing VLBA observations of H2O masers near the
star-forming region W3(OH) to measure their parallax and absolute proper
motions. The measured annual parallax is 0.489 +/- 0.017 milli-arcseconds (2.04
+/- 0.07 kpc), where the error is dominated by a systematic atmospheric
contribution. This distance is consistent with photometric distances from
previous observations and with the distance determined from CH3OH maser
astrometry presented in a related paper. We also find that the source driving
the H2O outflow, the ``TW-object'', moves with a 3-dimensional velocity of > 7
km/s relative to the ultracompact HII region W3(OH).


title: Magnetically Driven Jets in the Kerr Metric

abstract:
  We compute a series of three-dimensional general relativistic
magnetohydrodynamic simulations of accretion flows in the Kerr metric to
investigate the properties of the unbound outflows that result. The overall
strength of these outflows increases sharply with increasing black hole
rotation rate, but a number of generic features are found in all cases. The
mass in the outflow is concentrated in a hollow cone whose opening angle is
largely determined by the effective potential for matter orbiting with angular
momentum comparable to that of the innermost stable circular orbit. The
dominant force accelerating the matter outward comes from the pressure of the
accretion disk's corona. The principal element that shapes the outflow is
therefore the centrifugal barrier preventing accreting matter from coming close
to the rotation axis. Inside the centrifugal barrier, the cone contains very
little matter and is dominated by electromagnetic fields that rotate at a rate
tied closely to the rotation of the black hole. These fields carry an
outward-going Poynting flux whose immediate energy source is the rotating
spacetime of the Kerr black hole. When the spin parameter a/M of the black hole
exceeds ~0.9, the energy carried to infinity by these outflows can be
comparable to the nominal radiative efficiency predicted in the Novikov-Thorne
model. Similarly, the expelled angular momentum can be comparable to that
accreted by the black hole. Both the inner electromagnetic part and the outer
matter part can contribute in significant fashion to the energy and angular
momentum of the outflow.