title: Abundance analysis of cool extreme helium star: LSS 3378

abstract:
  Abundance analysis of the cool extreme helium (EHe) star LSS 3378 is
presented. The abundance analysis is done using LTE line formation and LTE
model atmospheres constructed for EHe stars.
  The atmosphere of LSS 3378 shows evidence of H-burning, He-burning, and
s-process nucleosynthesis. The derived abundances of iron-peak and
alpha-elements indicate absence of selective fractionation or any other
processes that can distort chemical composition of these elements. Hence, the
Fe abundance (log epsilon(Fe) = 6.1) is adopted as an initial metallicity
indicator. The measured abundances of LSS 3378 are compared with those of R
Coronae Borealis (RCB) stars and with rest of the EHe stars as a group.


title:
An analysis method for time ordered data processing of Dark Matter
  experiments

abstract:
  The analysis of the time ordered data of Dark Matter experiments is becoming
more and more challenging with the increase of sensitivity in the ongoing and
forthcoming projects. Combined with the well-known level of background events,
this leads to a rather high level of pile-up in the data. Ionization,
scintillation as well as bolometric signals present common features in their
acquisition timeline: low frequency baselines, random gaussian noise, parasitic
noise and signal characterized by well-defined peaks. In particular, in the
case of long-lasting signals such as bolometric ones, the pile-up of events may
lead to an inaccurate reconstruction of the physical signal (misidentification
as well as fake events). We present a general method to detect and extract
signals in noisy data with a high pile-up rate and qe show that events from few
keV to hundreds of keV can be reconstructed in time ordered data presenting a
high pile-up rate. This method is based on an iterative detection and fitting
procedure combined with prior wavelet-based denoising of the data and baseline
subtraction. {We have tested this method on simulated data of the MACHe3
prototype experiment and shown that the iterative fitting procedure allows us
to recover the lowest energy events, of the order of a few keV, in the presence
of background signals from a few to hundreds of keV. Finally we applied this
method to the recent MACHe3 data to successfully measure the spectrum of
conversion electrons from Co57 source and also the spectrum of the background
cosmic muons.


title:
Beyond the bubble catastrophe of Type Ia supernovae: Pulsating Reverse
  Detonation models

abstract:
  We describe a mechanism by which a failed deflagration of a
Chandrasekhar-mass carbon-oxygen white dwarf can turn into a successful
thermonuclear supernova explosion, without invoking an ad hoc high-density
deflagration-detonation transition. Following a pulsating phase, an accretion
shock develops above a core of 1 M_sun composed of carbon and oxygen, inducing
a converging detonation. A three-dimensional simulation of the explosion
produced a kinetic energy of 1.05E51 ergs and 0.70 M_sun of 56Ni, ejecting
scarcely 0.01 M_sun of C-O moving at low velocities. The mechanism works under
quite general conditions and is flexible enough to account for the diversity of
normal Type Ia supernovae. In given conditions the detonation might not occur,
which would reflect in peculiar signatures in the gamma and UV-wavelengths


title:
Accelerating universe in scalar tensor models - confrontation of
  theoretical predictions with observations

abstract:
  We consider scalar tensor theories of gravity assuming that the scalar field
is non minimally coupled with gravity. We use this theory to study evolution of
a flat homogeneous and isotropic universe. In this case the dynamical equations
can be derived form a point like Lagrangian. We study the general properties of
dynamics of this system and show that for a wide range of initial conditions
such models lead in a natural way to an accelerated phase of expansion of the
universe. Assuming that the point like Lagrangian admits a Noether symmetry we
are able to explicitly solve the dynamical equations. We study one particular
model and show that its predictions are compatible with observational data,
namely the publicly available data on type Ia supernovae, the parameters of
large scale structure determined by the 2-degree Field Galaxy Redshift Survey
(2dFGRS), the measurements of cosmological distances with the
Sunyaev-Zel'dovich effect and the rate of growth of density perturbations}{It
turns out that this model have a very interesting feature of producing in a
natural way an epoch of accelerated expansion. With an appropriate choice of
parameters our model is fully compatible with several observed characteristics
of the universe


title:
LIRIS multi-slit H_alpha spectroscopy of a z ~ 1 DEEP2 sample of
  star-forming galaxies

abstract:
  We present preliminary results of H_alpha near-infrared spectroscopy of six
galaxies with redshifts z ~ 1 drawn from the DEEP2 Galaxy Redshift Survey. The
spectra have been taken with the multi-slit mode of LIRIS (Long-slit
Intermediate Resolution Infrared Spectrograph) installed at the 4.2-m William
Herschel Telescope. This is a pilot study for a larger program to obtain
H_alpha luminosities of about 50 star-forming galaxies at z ~ 1, with the aim
of deriving the corresponding star formation rates (SFRs) from H_alpha as well
as studying the relationship with other SFR indicators. The new galaxy sample
will be selected from the Extended Groth Strip Survey, where galaxies will also
have measures of stellar masses, reddening, far-IR data, and galaxy
morphologies.


title:
Who Is Eating the Outflow?: High-Angular Resolution Study of an
  Intermediate-Mass Protostar in L1206

abstract:
  Up to now only a few intermediate-mass molecular outflows have been studied
with enough high-angular resolution. The aim of this work is to study in detail
the intermediate-mass YSO IRAS 22272+6358A, which is embedded in L1206, and its
molecular outflow, in order to investigate the interaction of the outflow with
the dense protostellar material, and to compare their properties with those of
lower mas counterparts. We carried out OVRO observations of the 2.7 mm
continuum emission, CO(1-0), C18O(1-0), and HC3N(12-11) in order to map with
high-angular resolution the core of L1206, and to derive the properties of the
dust emission, the molecular outflow and the dense protostellar envelope. The
2.7 mm continuum emission has been resolved into four sources, labeled OVRO~1,
2, 3, and 4. The intermediate-mass Class~0/I object OVRO 2, with a mass traced
by the dust emission of 14.2 Msun, is the source associated with IRAS
22272+6358A. The CO(1-0) observations have revealed a very collimated outflow
driven by OVRO 2, at a PA ~140 degr, that has a very weak southeastern red lobe
and a much stronger northwestern blue lobe. Photodissociation toward the red
lobe produced by the ionization front coming from the bright-rimmed diffuse HII
region could be responsible of the morphology of the outflow. The spatial
correlation between the outflow and the elongated dense protostellar material
traced by HC3N(12-11) suggests an interaction between the molecular outflow and
the protostellar envelope. Shocks produced by the molecular outflow, and
possibly by the shock front preceding the ionization front could account for
the southern enhancement of HC3N. The properties of the intermediate-mass
protostar OVRO 2 and the molecular outflow are consistent with those of lower
mass counterparts.


title:
A 62 Day X-Ray Periodicity and an X-Ray Flare from the Ultraluminous
  X-Ray Source in M82

abstract:
  In 240 days of X-ray monitoring of M82, we have discovered an X-ray
periodicity at $62.0 \pm 2.5$ days with a peak to peak amplitude corresponding
to an isotropic luminosity of $2.4 \times 10^{40} \rm erg s^{-1}$ in M82 and an
X-ray flare reaching a peak luminosity of $9.8 \times 10^{40} \rm erg s^{-1}$.
The periodicity and flare likely originate from the ultraluminous X-ray source
(ULX) in M82 which has been identified as a possible intermediate mass black
hole. We suggest that the 62~day modulation is due to orbital motion within an
X-ray binary with a Roche-lobe overflowing companion star which would imply
that the average density of the companion star is near $5 \times 10^{-5} \rm g
cm^{-3}$ and is therefore a giant or supergiant. Chandra observations just
after the flare show an energy spectrum that is consistent with a power-law
with no evidence of a thermal component or line emission. Radio observations
made with the VLA during the flare allow us to rule out a blazar identification
for the source and place strong constraints on relativistically beamed models
of the X-ray emission. The Chandra observations reveal a second X-ray source
reached a flux of $4.4 \times 10^{-12} \rm erg cm^{-2} s^{-1}$ in the 0.3-7 keV
band which is dramatically higher than any flux previously seen from this
source and corresponds to an isotropic luminosity of $1.1 \times 10^{40} \rm
erg s^{-1}$. This source is a second ultraluminous X-ray source in M82 and may
give rise to the QPOs detected from the central region of M82.


title: High resolution infrared spectroscopy of the old open cluster NGC6791

abstract:
  We report abundance analysis for 6 M giant members of the old open cluster
NGC6791, based on infrared spectroscopy (1.5-1.8 micron) at R=25,000, using the
NIRSPEC spectrograph at the Keck II telescope. We find the iron abundance
<[Fe/H]>= +0.35 +/- 0.02$, confirming the super solar metallicity of this
cluster derived from optical medium-high resolution spectroscopy. We also
measure C, O and other alpha element abundances, finding roughly solar
[alpha/Fe] and <[C/Fe]> = -0.35. Our approach constrains [O/Fe] especially
well, based on the measurement of a number of OH lines near 1.6micron; we find
[O/Fe]=-0.07 +/-0.03. The Solar alpha enhancement is in contrast to the
composition of similar stars in the Galactic bulge. We also find low
12C/13C~10, confirming the presence of extra-mixing processes during the red
giant phase of evolution, up to super solar metallicities.


title: Disk Evolution in Young Binaries: from Observations to Theory

abstract:
  The formation of a binary system surrounded by disks is the most common
outcome of stellar formation. Hence studying and understanding the formation
and the evolution of binary systems and associated disks is a cornerstone of
star formation science. Moreover, since the components within binary systems
are coeval and the sizes of their disks are fixed by the tidal truncation of
their companion, binary systems provide an ideal "laboratory" in which to study
disk evolution under well defined boundary conditions.
  In this paper, we review observations of several inner disk diagnostics in
multiple systems, including hydrogen emission lines (indicative of ongoing
accretion), $K-L$ and $K-N$ color excesses (evidence of warm inner disks), and
polarization (indicative of the relative orientations of the disks around each
component). We examine to what degree these properties are correlated within
binary systems and how this degree of correlation depends on parameters such as
separation and binary mass ratio. These findings will be interpreted both in
terms of models that treat each disk as an isolated reservoir and those in
which the disks are subject to re-supply from some form of circumbinary
reservoir, the observational evidence for which we will also critically review.
The planet forming potential of multiple star systems is discussed in terms of
the relative lifetimes of disks around single stars, binary primaries and
binary secondaries. Finally, we summarize several potentially revealing
observational problems and future projects that could provide further insight
into disk evolution in the coming decade


title:
The (54Fe+58Ni)/56Ni ratio as a second parameter for Type Ia supernova
  properties

abstract:
  A variation of the relative content of (54Fe+58Ni) versus 56Ni may be
responsible for the observed scatter of Type Ia Supernovae (SNe Ia) about a
mean relation between their intrinsic brightness and the shape of their light
curve. Synthetic light curves are computed of parametrised Chandrasekhar-mass
explosion models of constant kinetic energy, where the ejecta are divided into
an inner NSE zone, composed of (54Fe+58Ni) inside and 56Ni outside, an outer
zone with Intermediate Mass Elements and a CO zone. Both the size of the NSE
zone and the fraction of (54Fe+58Ni) v. 56Ni are varied systematically. Models
with the same original NSE content but different (54Fe+58Ni)/56Ni ratios reach
different peak brightness but have similar light curve shapes. Synthetic
spectra indicate that the V-band decline rate is not affected by the
(54Fe+58Ni)/56Ni ratio. While the 56Ni mass and the total NSE mass are the
dominant parameters determining the peak luminosity and the shape of the light
curve, respectively, a variation in the (54Fe+58Ni)/56Ni ratio, which may
depend on the metallicity of the progenitor (Timmes, Brown & Truran 2003) is
likely to account for a significant part of the observed scatter of local SNe
Ia about the mean brightness--decline rate relation.


title:
Study of the Structure of the Coma Cluster Based on a Hierarchical
  Powerful Clustering Method

abstract:
  Six subclusters in the Coma cluster have been selected on the basis of a
hierarchical clustering method that takes the gravitational interaction among
galaxies into account. Of these, three main subclusters around the galaxies NGC
4889, NGC 4874, and NGC 4839 have been singled out. We have used the objective
statistical criterion applied by Vennik and Anosova in studies of close groups
of galaxies to evaluate each member included in a subcluster with a high
probability. Galaxies with a significant deficit of hydrogen HI, including
objects from the Bravo-Alfaro list,have been identified with members of the
subclusters, with the greatest number of them in the subclusters around NGC
4874 and NGC 4839. A quantitative estimate of the hydrogen deficit using the HI
index in the RCG3 catalog reveals a statistically significant excess value for
those galaxies that are members of the subclusters compared to the field
galaxies with a hydrogen deficit in the studied area of Coma cluster. A
substantial number of the spiral galaxies with a hydrogen deficit in the
subclusters turned out to be radio galaxies as well.


title: Vortices in Thin, Compressible, Unmagnetized Disks

abstract:
  We consider the formation and evolution of vortices in a hydrodynamic
shearing-sheet model. The evolution is done numerically using a version of the
ZEUS code. Consistent with earlier results, an injected vorticity field evolves
into a set of long-lived vortices, each of which has a radial extent comparable
to the local scale height. But we also find that the resulting velocity field
has a positive shear stress, <Sigma delta v_r delta v_phi>. This effect appears
only at high resolution. The transport, which decays with time as t^-1/2,
arises primarily because the vortices drive compressive motions. This result
suggests a possible mechanism for angular momentum transport in low-ionization
disks, with two important caveats: a mechanism must be found to inject
vorticity into the disk, and the vortices must not decay rapidly due to
three-dimensional instabilities.


title: Near-Field Cosmology with Horizontal Branch and RR Lyrae Stars

abstract:
  The importance of horizontal branch and RR Lyrae stars is discussed in the
context of cosmological arguments for the formation of the Galactic halo and
its satellite dwarf galaxies. It is shown, in particular, that the Galactic
halo globular cluster system cannot have formed from the accretion of
``protogalactic fragments'' resembling the very early counterparts of the
present-day dwarf satellite galaxies of the Milky Way, or else its RR Lyrae
properties would be very different from what is currently observed.


title: Analysis of 26 Barium Stars I. Abundances

abstract:
  We present a detailed analysis of 26 barium stars, including dwarf barium
stars, providing their atmospheric parameters (Teff, log g, [Fe/H], vt) and
elemental abundances. We aim at deriving gravities and luminosity classes of
the sample stars, in particular to confirm the existence of dwarf barium stars.
Accurate abundances of chemical elements were derived. Abundance ratios between
nucleosynthetic processes, by using Eu and Ba as representatives of the r- and
s-processes are presented. High-resolution spectra with the FEROS spectrograph
at the ESO-1.5m Telescope, and photometric data with Fotrap at the Zeiss
telescope at the LNA were obtained. The atmospheric parameters were derived in
an iterative way, with temperatures obtained from colour-temperature
calibrations. The abundances were derived using spectrum synthesis for Li, Na,
Al, alpha-, iron peak, s- and r-elements atomic lines, and C and N molecular
lines. Atmospheric parameters in the range 4300 < Teff < 6500, -1.2 < [Fe/H] <
0.0 and 1.4 < log g < 4.6 were derived, confirming that our sample contains
giants, subgiants and dwarfs. The abundance results obtained for Li, Al, Na,
alpha- and iron peak elements for the sample stars show that they are
compatible with the values found in the literature for normal disk stars in the
same range of metallicities. Enhancements of C, N and heavy elements relative
to Fe, that characterise barium stars, were derived and showed that [X/Ba] vs.
[Ba/H] and [X/Ba] vs. [Fe/H] present different behaviour as compared to [X/Eu]
vs. [Eu/H] and [X/Eu] vs. [Fe/H], reflecting the different nucleosynthetic
sites for the s- and r-processes.


title:
Discovery of the new slowly pulsating B star HD 163830 (B5II/III) from
  MOST spacebased photometry

abstract:
  We report the discovery of a new slowly pulsating B (SPB) star, with the
largest number of detected frequencies to date by more than a factor of three,
based on 37 days of MOST (Microvariability & Oscillations of STars) satellite
guide star photometry. The star HD 163830 (V = 9.3, B5II/III) varies in twenty
detected frequencies in the range $0.035 - 1.06$ d$^{-1}$ ($0.4 - 12.3 ~
\mu$Hz) with amplitudes from 0.7 to 7.6 mmag ($S/N$ from {4 to 43}). Eighteen
of these frequencies are consistent with low-degree, high-order nonradial
g-modes {of seismic models of an evolved 4.5$M_{\odot}$ star. We are unable to
identify one unique model due to lack of mode identifications. The lowest two
frequencies may be associated with the rotation of HD 163830, but firm proof of
this must await future spectroscopic data.


title: N-Body Simulations of Alternate Gravity Models

abstract:
  Theories in which gravity is weaker on cosmological scales have been proposed
to explain the observed acceleration of the universe. The nonlinear regime in
such theories is not well studied, though it is likely that observational tests
of structure formation will lie in this regime. A class of alternate gravity
theories may be approximated by modifying Poisson's equation. We have run
N-body simulations of a set of such models to study the nonlinear clustering of
matter on 1-100 Mpc scales. We find that nonlinear gravity enhances the
deviations of the power spectrum of these models from standard gravity. This
occurs due to mode-coupling, so that models with an excess or deficit of
large-scale power (at k < 0.2/Mpc) lead to deviations in the power spectrum at
smaller scales as well (up to k ~ 1/Mpc), even though the linear spectra match
very closely on the smaller scales. This makes it easier to distinguish such
models from general relativity using the three-dimensional power spectrum
probed by galaxy surveys and the weak lensing power spectrum. If the potential
for light deflection is modified in the same way as the potential that affects
the dark matter, then weak lensing constrains deviations from gravity even more
strongly. Our simulations show that even with a modified potential,
gravitational evolution is approximately universal. Based on this, the
Peacock-Dodds approach can be adapted to get an analytical fit for the
nonlinear power spectra of alternate gravity models, though the recent Smith et
al formula is less successful. Our conclusions extend to models with
modifications of gravity on scales of 1-20 Mpc. We also use a way of measuring
projected power spectra from simulations that lowers the sample variance, so
that fewer realizations are needed to reach a desired level of accuracy.


title:
X-ray and Sunyaev-Zel'dovich Effect Measurements of the Gas Mass
  Fraction in Galaxy Clusters

abstract:
  We present gas mass fractions of 38 massive galaxy clusters spanning
redshifts from 0.14 to 0.89, derived from Chandra X-ray data and OVRO/BIMA
interferometric Sunyaev-Zel'dovich Effect measurements. We use three models for
the gas distribution: (1) an isothermal beta-model fit jointly to the X-ray
data at radii beyond 100 kpc and to all of the SZE data,(2) a non-isothermal
double beta-model fit jointly to all of the X-ray and SZE data, and (3) an
isothermal beta-model fit only to the SZE spatial data. We show that the simple
isothermal model well characterizes the intracluster medium (ICM) outside of
the cluster core in clusters with a wide range of morphological properties. The
X-ray and SZE determinations of mean gas mass fractions for the 100 kpc-cut
isothermal beta-model are fgas(X-ray)=0.110 +0.003-0.003 +0.006-0.018 and
fgas(SZE)=0.116 +0.005-0.005 +0.009-0.026, where uncertainties are statistical
followed by systematic at 68% confidence. For the non-isothermal double
beta-model, fgas(X-ray)=0.119 +0.003-0.003 +0.007-0.014 and fgas(SZE)=0.121
+0.005-0.005 +0.009-0.016. For the SZE-only model, fgas(SZE)=0.120 +0.009-0.009
+0.009-0.027. Our results indicate that the ratio of the gas mass fraction
within r2500 to the cosmic baryon fraction is 0.68 +0.10-0.16 where the range
includes statistical and systematic uncertainties. By assuming that cluster gas
mass fractions are independent of redshift, we find that the results are in
agreement with standard LambdaCDM cosmology and are inconsistent with a flat
matter dominated universe.


title: The Global 21 Centimeter Background from High Redshifts

abstract:
  We consider the evolution of the sky-averaged 21 cm background during the
early phases of structure formation. Using simple analytic models, we calculate
the thermal and ionization histories, assuming that stellar photons dominate
the radiation background. The resulting 21 cm spectra can constrain the
properties of the first generations of stars and quasars. If Population II
stars dominate, Lyman-alpha coupling renders the IGM visible before it is
heated by X-rays and long before reionization. Thus the 21 cm background has a
strong absorption epoch followed by weaker emission that fades during
reionization. The harder spectra of very massive Population III stars compress
these transitions into a shorter time interval and decreases the signal
amplitude. However, the reionization epoch will remain visible except in
extreme cases. The global 21 cm signal will be challenging to observe because
of astronomical foregrounds, but it offers an exciting opportunity to study the
first sources of light. It also fixes the overall amplitude of the fluctuating
background whose detection is a major goal of several next-generation
low-frequency radio interferometers.


title: The Stellar, Gas and Dynamical Masses of Star-Forming Galaxies at z~2

abstract:
  We present analysis of the near-infrared spectra of 114 rest-frame
UV-selected star-forming galaxies at z~2. By combining the H-alpha spectra with
photometric measurements from observed 0.3--8 micron, we assess the
relationships between kinematics, dynamical masses, inferred gas fractions, and
stellar masses and ages. The H-alpha line widths give a mean dynamical mass
M_dyn=6.9 +/- 0.6 x 10^10 Msun within a typical radius of ~6 kpc, after
excluding AGN. The average dynamical mass is ~2 times larger than the average
stellar mass, and the two agree to within a factor of several for most objects.
However, ~15% of the sample has M_dyn >> M_star. These objects are best fit by
young stellar populations and tend to have high H-alpha equivalent widths,
suggesting that they are young starbursts with large gas masses. Rest-frame
optical luminosity and velocity dispersion are correlated with 4 sigma
significance. Using the local empirical correlation between star formation rate
per unit area and gas surface density, we estimate the mass of the gas
associated with star formation, and find a mean gas fraction of ~50% and a
strong decrease in gas fraction with increasing stellar mass. The masses of gas
and stars combined are considerably better correlated with the dynamical masses
than are the stellar masses alone, and agree to within a factor of three for
85% of the sample. The combination of kinematic measurements, estimates of gas
masses, and stellar population properties suggest that the factor of ~500 range
in stellar mass across the sample cannot be fully explained by intrinsic
differences in the total masses of the galaxies, which vary by a factor of ~40;
the remaining variation is due to the evolution of the stellar population and
the conversion of gas into stars. [Abridged]


title: A Compact Supermassive Binary Black Hole System

abstract:
  We report on the discovery of a supermassive binary black hole system in the
radio galaxy 0402+379, with a projected separation between the two black holes
of just 7.3 pc. This is the closest black hole pair yet found by more than two
orders of magnitude. These results are based upon recent multi-frequency
observations using the Very Long Baseline Array (VLBA) which reveal two
compact, variable, flat-spectrum, active nuclei within the elliptical host
galaxy of 0402+379. Multi-epoch observations from the VLBA also provide
constraints on the total mass and dynamics of the system. Low spectral
resolution spectroscopy using the Hobby-Eberly Telescope indicates two velocity
systems with a combined mass of the two black holes of ~1.5 x 10^8 solar
masses. The two nuclei appear stationary while the jets emanating from the
weaker of the two nuclei appear to move out and terminate in bright hot spots.
The discovery of this system has implications for the number of close binary
black holes that might be sources of gravitational radiation. Green Bank
Telescope observations at 22 GHz to search for water masers in this interesting
system are also presented.


title:
Spreading of thermonuclear flames on the neutron star in SAX
  J1808.4-3658: an observational tool

abstract:
  We analyse archival Rossi X-Ray Timing Explorer (RXTE) proportional counter
array (PCA) data of thermonuclear X-ray bursts from the 2002 outburst of the
accreting millisecond pulsar SAX J1808.4-3658. We present evidence of
nonmonotonic variations of oscillation frequency during burst rise, and
correlations among the time evolution of the oscillation frequency, amplitude,
and the inferred burning region area. We also discuss that the amplitude and
burning region area evolutions are consistent with thermonuclear flame
spreading on the neutron star surface. Based on this discussion, we infer that
for the 2002 Oct. 15 thermonuclear burst, the ignition likely occured in the
mid-latitudes, the burning region took ~ 0.2 s to nearly encircle the
equatorial region of the neutron star, and after that the lower amplitude
oscillation originated from the remaining asymmetry of the burning front in the
same hemisphere where the burst ignited. Our observational findings and
theoretical discussion indicate that studies of the evolution of burst
oscillation properties during burst rise can provide a powerful tool to
understand thermonuclear flame spreading on neutron star surfaces under extreme
physical conditions.


title:
The Starburst in the Abell 1835 Cluster Central Galaxy: A Case Study of
  Galaxy Formation Regulated by an Outburst from a Supermassive Black Hole

abstract:
  We present an optical, X-ray, and radio analysis of the starburst in the
Abell 1835 cluster's central cD galaxy. The dense gas surrounding the galaxy is
radiating X-rays with a luminosity of ~1E45 erg/s consistent with a cooling
rate of ~1000-2000 solar masses per year. However, Chandra and XMM-Newton
observations find less than 200 solar masses per year of gas cooling below ~2
keV, a level that is consistent with the cD's current star formation rate of
100-180 solar masses per year. One or more heating agents (feedback) must then
be replenishing the remaining radiative losses. The heat fluxes from supernova
explosions and thermal conduction alone are unable to do so. However, a pair of
X-ray cavities from an AGN outburst has deposited ~1.7E60 erg into the
surrounding gas over the past 40 Myr. The corresponding jet power 1.4E45
erg/sec is enough to offset most of the radiative losses from the cooling gas.
The jet power exceeds the radio synchrotron power by ~4000 times, making this
one of the most radiatively inefficient radio sources known. The large jet
power implies that the cD's supermassive black hole accreted at a mean rate of
  ~0.3 solar masses per year over the last 40 Myr or so, which is a small
fraction of the Eddington accretion rate for a 10E9 solar mass black hole. The
ratio of the bulge growth rate through star formation and the black hole growth
rate through accretion is consistent with the slope of the (Magorrian)
relationship between bulge and central black hole mass in nearby quiescent
galaxies. The consistency between net cooling, heating (feedback), and the
cooling sink (star formation) in this system resolves the primary objection to
traditional cooling flow models. (abridged)


title:
A Revised Prescription for the Tayler-Spruit Dynamo: Magnetic Angular
  Momentum Transport in Stars

abstract:
  Angular momentum transport by internal magnetic fields is an important
ingredient for stellar interior models. In this paper we critically examine the
basic heuristic assumptions in the model of the Tayler-Spruit dynamo, which
describes how a pinch-type instability of a toroidal magnetic field in
differentially rotating stellar radiative zones may result in large-scale fluid
motion. We agree with prior published work both on the existence of the
instability and its nearly horizontal geometry for perturbations. However, the
approximations in the original Acheson dispersion relation are valid only for
small length scales, and we disagree that the dispersion relation can be
extrapolated to horizontal length scales of order the radius of the star. We
contend that dynamical effects, in particular angular momentum conservation,
limit the maximum horizontal length scale. We therefore present transport
coefficients for chemical mixing and angular momentum redistribution by
magnetic torques that are significantly different from previous published
values. The new magnetic viscosity is reduced by 2 to 3 orders of magnitude
compared to the old one, and we find that magnetic angular momentum transport
by this mechanism is very sensitive to gradients in the mean molecular weight.
The revised coefficients are more compatible with empirical constraints on the
timescale of core-envelope coupling in young stars than the previous ones.
However, solar models including only this mechanism possess a rapidly rotating
core, in contradiction with helioseismic data. (abridged)


title:
Detection of Highly Ionized Metal Absorption Lines in the Ultracompact
  X-ray Dipper 4U 1916-05

abstract:
  We present the high-resolution Chandra X-ray Observatory persistent (non-dip)
spectrum of 4U 1916-05 which revealed narrow absorption lines from hydrogenic
neon, magnesium, silicon, and sulfur, in addition to the previous identified
hydrogenic and helium-like iron absorption lines. This makes 4U 1916-05 only
the second of the classical X-ray dipper systems to show narrow absorption
lines from elements other than iron. We propose two possible explanations for
the small measured line widths (>~ 500-2000 km s^{-1}), compared to the
expected Keplerian velocities (> 1000 km s^{-1}) of the accretion disk in this
50-min orbital period system, and lack of wavelength shifts (>~ 250 km s^{-1}).
First, the ionized absorber may be stationary. Alternatively, the line
properties may measure the relative size of the emission region. From this
hypothesis, we find that the emission region is constrained to be >~ 0.25 times
the radial extent of the absorber. Our results also imply that the ionized
absorber spans a range of ionization parameters.


title: Hydrogen in Type Ic Supernovae?

abstract:
  By definition, a Type Ic supernova (SN Ic) does not have conspicuous lines of
hydrogen or helium in its optical spectrum. SNe Ic usually are modelled in
terms of the gravitational collapse of bare carbon-oxygen cores. We consider
the possibility that the spectra of ordinary (SN 1994I-like) SNe Ic have been
misinterpreted, and that SNe Ic eject hydrogen. An absorption feature usually
attributed to a blend of Si II 6355 and C II 6580 may be produced by H-alpha.
If SN 1994I-like SNe Ic eject hydrogen, the possibility that hypernova (SN
1998bw-like) SNe Ic, some of which are associated with gamma-ray bursts, also
eject hydrogen should be considered. The implications of hydrogen for SN Ic
progenitors and explosion models are briefly discussed.


title:
Sensitivity of time-distance helioseismic measurements to spatial
  variation of oscillation amplitudes I. Observations and a numerical model

abstract:
  It is well known that the observed amplitude of solar oscillations is lower
in sunspots than in quiet regions of the Sun. We show that this local reduction
in oscillation amplitudes combined with the phase-speed filtering procedure in
time-distance helioseismic analyses could be a source of systematic errors in
the range of 5 - 40% in the measured travel-time anomalies of acoustic waves
around sunspots. Removing these travel time artifacts is important for
correctly inferring the subsurface structure of sunspots. We suggest an
empirical correction procedure and illustrate its usage for a small sunspot.
This work utilizes data from MDI/SOHO.


title:
Survey for Transiting Extrasolar Planets in Stellar Systems IV:
  Variables in the Field of NGC 1245

abstract:
  The Survey for Transiting Extrasolar Planets in Stellar Systems (STEPSS)
project is a search for planetary transits in open clusters. In this paper, we
analyze the STEPSS observations of the open cluster NGC 1245 to determine the
variable star content of the cluster. Out of 6787 stars observed with V < 22,
of which ~870 are cluster members, we find 14 stars with clear intrinsic
variability that are potential cluster members, and 29 clear variables that are
not cluster members. None of these variables have been previously identified.
We present light curves, finding charts, and stellar/photometric data on these
variable objects. Several of the interacting binaries have estimated distances
consistent with the cluster distance determined from isochrone fits to the
color magnitude diagram. Four stars at the main sequence turnoff of the cluster
have light curves consistent with gamma Doradus variability. If these gamma
Doradus candidates are confirmed, they represent the oldest and coolest members
of this class of variable discovered to date.


title: The First Stars in The Universe

abstract:
  Large telescopes have allowed astronomers to observe galaxies that formed as
early as 850 million years after the Big Bang. We predict when the first star
that astronomers can observe formed in the universe, accounting for the first
time for the size of the universe and for three essential ingredients: the
light travel time from distant galaxies, Poisson and density fluctuations on
all scales, and the effect of very early cosmic history on galaxy formation. We
find that the first observable star is most likely to have formed 30 million
years after the Big Bang (at redshift 65), much earlier than previously
expected. Also, the first galaxy as massive as our own Milky Way likely formed
when the universe was only 400 Myr old (at redshift 11). We also show that
significant modifications are required in current methods of numerically
simulating the formation of galaxies at redshift 20 and above.


title:
Robust Dark Energy Constraints from Supernovae, Galaxy Clustering, and
  Three-Year Wilkinson Microwave Anisotropy Probe Observations

abstract:
  Type Ia supernova (SN Ia), galaxy clustering, and cosmic microwave background
anisotropy (CMB) data provide complementary constraints on the nature of the
dark energy in the universe. We find that the three-year Wilkinson Microwave
Anisotropy Probe (WMAP) observations give a CMB shift parameter of R =
(\Omega_m H_0^2)^{1/2} \int_0^{z_{CMB}} dz'/H(z')= 1.70 \pm 0.03. Using this
new measured value of the CMB shift parameter, together with the baryon
acoustic oscillation (BAO) measurement from the Sloan Digital Sky Survey
(SDSS), and SN Ia data from the HST/GOODS program and the first year Supernova
Legacy Survey, we derive model-independent constraints on the dark energy
density rho_X(z) and the cosmic expansion rate H(z). We also derive constraints
on the dark energy equation of state w_X(z)=w_0+w'z (with cutoff at z=2) and
w_X(a)=w_0+(1-a)w_a.
  We find that current data provide slightly tighter constraints on rho_X(z)
and H(z) as free functions in redshift, and roughly a factor of two improvement
in constraining w_X(z). A cosmological constant remains consistent with data,
however, uncertainties remain large for model-independent constraints of dark
energy. Significant increase in the number of observed SNe Ia between redshifts
of 1 and 2, complemented by improved BAO and weak lensing cosmography
measurements (as expected from the JEDI mission concept for the Joint Dark
Energy Mission), will be required to dramatically tighten model-independent
dark energy constraints.


title: Molecular Line Observations of a Carbon-Chain-Rich Core L492

abstract:
  We report on molecular abundances and distributions in a starless dense core
L492. We have found that the abundances of carbon-chain molecules such as CCS,
C$_{3}$S, HC$_{3}$N, HC$_{5}$N, and HC$_{7}$N are comparable to those in
chemically young dark cloud cores called "carbon-chain--producing regions",
such as L1495B, L1521B, L1521E, and TMC-1. This is the first dark cloud core
with extremely rich in carbon-chain-molecules that is found outside the Taurus
region. In addition, the deuterium fractionation ratios of DNC/HNC and
DCO$^{+}$/HCO$^{+}$ are also comparable to those in carbon-chain--producing
regions, being significantly lower than those in the evolved prestellar cores
such as L1498 and L1544. On the other hand, the abundances of NH$_{3}$ and
N$_{2}$H$^{+}$ are systematically higher than those in carbon-chain--producing
regions. Our mapping observations reveal that the central hole of molecular
distributions, which were reported for CCS and C$^{34}$S in evolved prestellar
cores is not significant in L492, indicating that the depletion factor of
molecules is not very high. Furthermore, L492 is dynamically more evolved than
carbon-chain--producing regions, and the protostellar collapse has started like
L1498 and L1544. Therefore, it is likely that the chemical and dynamical
evolutionary stage of L492 is intermediate between carbon-chain--producing
regions (L1495B, L1521B, L1521E, and TMC-1) and evolved prestellar cores (L1498
and L1544).


title: Which jet launching mechanism(s) in TTauri stars?

abstract:
  AIMS: We examine whether ejection phenomena from accreting T Tauri stars can
be described by only one type of self-collimated jet model. METHODS: We present
analytical kinematic predictions valid soon after the Alfv\'en surface for all
types of steady magnetically self-confined jets. RESULTS: We show that extended
disc winds, X-winds, and stellar winds occupy distinct regions in the poloidal
speed vs. specific angular momentum plane. Comparisons with current
observations of T Tauri jets yield quantitative constraints on the range of
launching radii, magnetic lever arms, and specific energy input in disc and
stellar winds. Implications on the origin of jet asymmetries and disc magnetic
fields are outlined. CONCLUSIONS: We argue that ejection phenomena from
accreting T Tauri stars most likely include three dynamical components: (1) an
outer self-collimated steady disc wind carrying most of the mass-flux in the
optical jet (when present), confining (2) a pressure-driven coronal stellar
wind and (3) a hot inner flow made of blobs sporadically ejected from the
magnetopause. If the stellar magnetic moment is parallel to the disc magnetic
field, then the highly variable inner flow resembles a "Reconnection X-wind",
that has been proven to efficiently brake down an accreting and contracting
young star. If the magnetic moment is anti-parallel, then larger versions of
the solar coronal mass ejections are likely to occur. The relative importance
of these three components in the observed outflows and the range of radii
involved in the disc wind are expected to vary with time, from the stage of
embedded source to the optically revealed T Tauri star phase.


title:
A deep photometric survey of the eta Chamaeleontis cluster down to the
  brown dwarf - planet boundary

abstract:
  We report the outcome of the deep optical/infrared photometric survey of the
central region (33 X 33 arcmin or 0.9 pc^2) of the eta Chamaeleontis pre-main
sequence star cluster. The completeness limits of the photometry are I = 19.1,
J = 18.2 and H = 17.6; faint enough to reveal low mass members down to the
brown dwarf and planet boundary of ~ 13 M_Jup. We found no such low mass
members in this region. Our result combined with a previous shallower (I = 17)
but larger area survey indicates that low mass objects (0.013 < M/M(solar mass)
< 0.075) either were not created in the eta Cha cluster or were lost due to the
early dynamical history of the cluster and ejected to outside the surveyed
areas.


title:
Can the Brans-Dicke Gravity with $\Lambda$ Possibly be a Theory of Dark
  Matter?

abstract:
  The pure Brans-Dicke (BD) gravity with or without the cosmological constant
$\Lambda $ has been taken as a model theory for the dark matter. Indeed, there
has been a consensus that unless one modifies either the standard theory of
gravity, namely, general relativity, or the standard model for particle
physics, or both, one can never achieve a satisfying understanding of the
phenomena associated with dark matter and dark energy. Along this line, our
dark matter model in this work can be thought of as an attempt to modify the
gravity side alone in the simplest fashion to achieve the goal. Among others,
it is demonstrated that our model theory can successfully predict the emergence
of dark matter halo-like configuration in terms of a self-gravitating spacetime
solution to the BD field equations and reproduce the flattened rotation curve
in this dark halo-like object in terms of the non-trivial energy density of the
BD scalar field, which was absent in the context of general relativity where
Newton's constant is strictly a ``constant'' having no dynamics. Our model
theory, however, is not entirely without flaw, such as the prediction of
relativistic jets in all types of galaxies which actually is not the case.


title: Oscillations in the stable starless core Barnard 68

abstract:
  New molecular line observations of the Bok globule Barnard 68 in HCO+
irrefutably confirm the complex pattern of red and blue asymmetric line
profiles seen across the face of the cloud in previous observations of CS. The
new observations thus strengthen the previous interpretation that Barnard 68 is
undergoing peculiar oscillations. Furthermore, the physical chemistry of B68
indicates that the object is much older than the sound crossing time and is
therefore long-lived. A model is presented for the globule in which a modest
external pressure perturbation is shown to lead to oscillations about a stable
equilibrium configuration. Such oscillations may be present in other stable
starless cores as manifested by a similar signature of inward and outward
motions.


title:
On the transition of the adiabatic supernova remnant to the radiative
  stage in a nonuniform interstellar medium

abstract:
  Methods for estimation of different reference times which appear in the
description of transition of a strong adiabatic shock into the radiative era
are reviewed. The need for consideration of an additional transition subphase
in between the end of the adiabatic era and the beginning of the radiative
''pressure-driven snowplow'' stage for a shock running in the uniform or
nonuniform medium is emphasized. This could be of importance in particular for
studying the interaction of supernova remnants (SNRs) with molecular clouds and
therefore for understanding the processes of the cosmic ray production in such
systems. The duration of this subphase - about 70% of SNR age at its beginning
- is almost independent of the density gradient for media with increasing
density and is longer for higher supernova explosion energy and for smaller
density in the place of explosion. It is shown as well that if the density of
the ambient medium decreases then the cooling processes could differ from the
commonly accepted scenario of the ''thin dense radiative shell'' formation.
This property should be studied in the future because it is important for
models of nonspherical SNRs which could be only partially radiative.


title:
UV and FIR selected star-forming galaxies at z=0: differences and
  overlaps

abstract:
  We study two samples of local galaxies, one is UV (GALEX) selected and the
other FIR (IRAS) selected, to address the question whether UV and FIR surveys
see the two sides ('bright' and 'dark') of the star formation of the same
population of galaxies or two different populations of star forming galaxies.
No significant difference between the L$_{tot}$ ($=L_{60}+L_{FUV}$) luminosity
functions of the UV and FIR samples is found. Also, after the correction for
the `Malmquist bias' (bias for flux limited samples), the FIR-to-UV ratio v.s.
L$_{tot}$ relations of the two samples are consistent with each other. In the
range of $9 \la \log(L_{tot}/L_\sun) \la 12$, both can be approximated by a
simple linear relation of $\log (L_{60}/L_{FUV})=\log(L_{tot}/L_\sun)-9.66$.
These are consistent with the hypothesis that the two samples represent the
same population of star forming galaxies, and their well documented differences
in L$_{tot}$ and in FIR-to-UV ratio are due only to the selection effect. A
comparison between the UV luminosity functions shows marginal evidence for a
population of faint UV galaxies missing in the FIR selected sample. The
contribution from these 'FIR-quiet' galaxies to the overall UV population is
insignificant, given that the K-band luminosity functions (i.e. the stellar
mass functions) of the two samples do not show any significant difference.


title:
Analysis of the dust evolution in the circumstellar disks of TTauri
  stars

abstract:
  We present a compositional analysis of 8-13um spectra of 32 young stellar
objects (YSOs). Our sample consists of 5 intermediate-mass stars and 27
low-mass stars. While the spectra and first scientific results have already
been published by Przygodda et al. (2003) and Kessler-Silacci et al. (2004) we
perform a more detailed analysis of the 10um silicate feature. In our analysis
we assume that this emission feature can be represented by a linear
superposition of the wavelength-dependent opacity $\kappa_{\rm abs}(\lambda)$
describing the optical properties of silicate grains with different chemical
composition, structure, and grain size. The determination of an adequate
fitting equation is another goal of this study. Using a restricted number of
fitting parameters we investigate which silicate species are necessary for the
compositional fitting. Particles with radii of 0.1um- and 1.5um consisting of
amorphous olivine and pyroxene, forsterite, enstatite, and quartz have been
considered. Only compact, homogeneous dust grains have been used in the
presented fitting procedures. In this context we show that acceptable fitting
results can also be achieved if emission properties of porous silicate grains
are considered instead. Although some previous studies give reasons for the
similarity between the dust in circumstellar disks of TTauri stars and Herbig
Ae/Be stars, a quantitative comparison has been missing, so far. Therefore, we
conclude with a discussion of the results of a 10um spectroscopic survey of van
Boekel et al. (2005) who focus on Herbig Ae/Be stars, the higher mass
counterparts of T Tauri stars and draw comparisons to this and other studies.
We find that the results of our study of T Tauri systems partly agree with
previous studies of Herbig Ae/Be stars.


title: Optical imaging of L723: the structure of HH 223

abstract:
  We imaged the Lynds 723 dark nebula (L723) with the aim of studying the
morphology of the Herbig-Haro object HH 223 and other line-emission nebula
detected in the region. We obtained deep narrow-band images in the Halpha and
[SII] lines and in the continuum nearby Halpha of a field of ~5' of the L723
dark nebula centered on HH 223. The Halpha and [SII] images reveal the detailed
morphology of HH 223, unresolved in previous optical images. Both images show a
quite complex knotty, wiggling structure embedded in a low-emission nebula.
Comparison between the [SII] and Halpha fluxes of the knots are indicative of
variations in the excitation conditions through HH 223. In addition, several
other faint nebula are detected in Halpha a few arcmin to the SE and to the NW
of HH 223, all of them lying projected onto the east-west pair of lobes of the
quadrupolar CO outflow. Comparison between the Halpha and the continuum images
confirms the HH-like nature of the Vrba object V83, while the Vrba objects V84
and V85 are identified as faint field stars.


title: Continuous optical monitoring during the prompt emission of GRB 060111B

abstract:
  We present the time-resolved optical emission of GRB 060111B during its
prompt phase, measured with the TAROT robotic observatory. This is the first
time that the optical emission from a gamma-ray burst has been continuously
monitored with a temporal resolution of a few seconds during the prompt
gamma-ray phase. The temporal evolution of the prompt optical emission at the
level of several seconds is used to provide a clue to the origin of this
emission. The optical emission was found to decay steadily from our first
measure, 28s after the trigger, in contrast to the gamma-ray emission, which
exhibits strong variability at the same time. This behaviour strongly suggests
that the optical emission is due to the reverse shock.


title: Planetary Microlensing: From Prediction to Discovery

abstract:
  Four planets have recently been discovered by gravitational microlensing. The
most recent of these discoveries is the lowest-mass planet known to exist
around a normal star. The detection of planets in gravitational microlensing
events was predicted over a decade ago. Microlensing is now a mature field of
astrophysical research and the recent planet detections herald a new chapter in
the hunt for low mass extra-solar planets. This paper reviews the basic theory
of planetary microlensing, describes the experiments currently in operation for
the detection and observation of microlensing events and compares the
characteristics of the planetary systems found to date by microlensing. Some
proposed schemes for improving the detection rate of planets via microlensing
are also discussed.


title:
Semi-empirical analysis of Sloan Digital Sky Survey galaxies: IV. A
  nature via nurture scenario for galaxy evolution

abstract:
  We investigate the environmental dependence of stellar population properties
of galaxies in the local universe. Physical quantities related to the stellar
content of galaxies are derived from a spectral synthesis method applied to a
volume-limited sample containing more than 60 thousand galaxies extracted from
the DR4 of the SDSS. Mean stellar ages, mean stellar metallicities and stellar
masses are obtained from this method and used to characterise the stellar
populations of galaxies. The environment is defined by the projected local
galaxy density estimated from a nearest neighbour approach. We recover the star
formation--density relation in terms of the mean light-weighted stellar age,
which is strongly correlated with star formation parameters derived from \Ha.
We find that the age--density relation is distinct when we divide galaxies
according to luminosity or stellar mass. The relation is remarkable for
galaxies in all bins of luminosity. On the other hand, only for an intermediate
stellar mass interval (associated to a transition in galaxy properties) the
relation shows a change in galaxy properties with environment. Such distinct
behaviours are associated to the large stellar masses of galaxies with the same
luminosity in high-density environments. In addition, the well known star
formation--density relation results from the prevalence of massive systems in
high-density environments, independently of galaxy luminosity, with the
additional observed downsizing in galaxy formation, in which the star formation
is shifted from massive galaxies at early times to low-mass galaxies as the
universe evolves. Our results support that a natural path for galaxy evolution
proceeds via a nurture way, in the sense that galaxy evolution is accelerated
in denser environments, that took place mainly at high-redshifts.


title:
Analysis of 26 Barium Stars II. Contributions of s-, r- and p-processes
  in the production of heavy elements

abstract:
  Barium stars show enhanced abundances of the slow neutron capture (s-process)
heavy elements, and for this reason they are suitable objects for the study of
s-process elements. The aim of this work is to quantify the contributions of
the s-, r- and p-processes for the total abundance of heavy elements from
abundances derived for a sample of 26 barium stars. The abundance ratios
between these processes and neutron exposures were studied. The abundances of
the sample stars were compared to those of normal stars thus identifying the
fraction relative to the s-process main component. The fittings of the sigmaN
curves (neutron capture cross section times abundance, plotted against atomic
mass number) for the sample stars suggest that the material from the companion
asymptotic giant branch star had approximately the solar isotopic composition
as concerns fractions of abundances relative to the s-process main component.
The abundance ratios of heavy elements, hs, ls and s and the computed neutron
exposure are similar to those of post-AGB stars. For some sample stars, an
exponential neutron exposure fits well the observed data, whereas for others, a
single neutron exposure provides a better fit. The comparison between barium
and AGB stars supports the hypothesis of binarity for the barium star
formation. Abundances of r-elements that are part of the s-process path in
barium stars are usually higher than those in normal stars,and for this reason,
barium stars seemed to be also enriched in r-elements, although in a lower
degree than s-elements. No dependence on luminosity classes was found in the
abundance ratios behaviour among the dwarfs and giants of the sample barium
stars.


title: Resolved Stellar Populations at the Distance of Virgo

abstract:
  Top of the wish list of any astronomer who wants to understand galaxy
formation and evolution is to resolve the stellar populations of a sample of
giant elliptical galaxies: to take spectra of the stars and make
Colour-Magnitude Diagrams going down to the oldest main sequence turn-offs. It
is only by measuring the relative numbers of stars on Main Sequence Turnoffs at
ages ranging back to the time of the earliest star formation in the Universe
that we can obtain unambiguous star formation histories. Understanding star
formation histories of individual galaxies underpins all our theories of galaxy
formation and evolution. To date we only have detailed star formation histories
for the nearest-by objects in the Local Group, namely galaxies within 700kpc of
our own. This means predominantly small diffuse dwarf galaxies in a poor group
environment. To sample the full range of galaxy types and to consider galaxies
in a high density environment (where much mass in the Universe resides) we need
to be able to resolve stars at the distance of the Virgo (~17Mpc) or Fornax
(~18Mpc) clusters. This ambitious goal requires an Extremely Large Telescope
(ELT), with a diameter of 50-150m, operating in the optical/near-IR at its
diffraction limit.


title: The Effect of Substructure on Mass Estimates of Galaxies

abstract:
  Large galaxies are thought to form hierarchically, from the accretion and
disruption of many smaller galaxies. Such a scenario should naturally lead to
galactic phase-space distributions containing some degree of substructure. We
examine the errors in mass estimates of galaxies and their dark halos made
using the projected phase-space distribution of a tracer population (such as a
globular cluster system or planetary nebulae) due to falsely assuming that the
tracers are distributed randomly. The level of this uncertainty is assessed by
applying a standard mass estimator to samples drawn from 11 random realizations
of galaxy halos containing levels of substructure consistent with current
models of structure formation. We find that substructure will distort our mass
estimates by up to ~20% - a negligible error compared to statistical and
measurement errors in current derivations of masses for our own and other
galaxies. However, this represents a fundamental limit to the accuracy of any
future mass estimates made under the assumption that the tracer population is
distributed randomly, regardless of the size of the sample or the accuracy of
the measurements.


title: Radiative transfer in protoplanetary disks

abstract:
  We present a new 3D continuum radiative transfer code, MCFOST, based on a
Monte-Carlo method. The reliability and efficiency of the code is tested by
comparison with five different radiative transfer codes previously tested by
Pascucci et al., 2004, using a 2D disk configuration. When tested against the
same disk configuration, no significant difference is found between the
temperature and SED calculated with MCFOST and with the other codes. The
computed values are well within the range of values computed by the other
codes. The code-to-code differences are small, they rarely exceed 10% and are
usually much smaller.


title: The SPITZER IRS view of stellar populations in Virgo early type galaxies

abstract:
  We have obtained high S/N Spitzer IRS spectra of 17 Virgo early-type galaxies
that lie on the colour-magnitude relation of passively evolving galaxies in the
cluster. To flux calibrate these extended sources we have devised a new
procedure that allows us to obtain the intrinsic spectral energy distribution
and to disentangle resolved and unresolved emission within the same object.
Thirteen objects of the sample (76%) show a pronounced broad silicate feature
(above 10micron) which is spatially extended and likely of stellar origin, in
agreement with model predictions. The other 4 objects (24%) are characterized
by different levels of activity. In NGC 4486 (M87) the line emission and the
broad silicate emission are evidently unresolved and, given also the typical
shape of the continuum, they likely originate in the nuclear torus. NGC 4636
show emission lines superimposed to extended silicate emission (i.e. likely of
stellar origin, pushing the percentage of galaxies with silicate emission to
82%). Finally NGC 4550 and NGC 4435 are characterized by PAH and line emission,
arising from a central unresolved region.


title: The Scientific Programme of Planck

abstract:
  For 40 years, the cosmic microwave background (CMB) has been the most
important source of information about the geometry and contents of the
Universe. Even so, only a small fraction of the information available in the
CMB has been extracted to date. Planck, the third space CMB mission after COBE
and WMAP, is designed to extract essentially all of the information in the CMB
temperature anisotropies. Planck will also measure to high accuracy the
polarization of CMB anisotropies, which encodes not only a wealth of
cosmological information but also provides a unique probe of the thermal
history of the Universe during the time when the first stars and galaxies
formed. Polarization measurements may also detect the signature of a stochastic
background of gravitational waves generated during inflation, 10^(-35) s after
the Big Bang. This book describes the expected scientific output of the Planck
mission, both cosmological and non-cosmological. Chapter 1 summarizes the
experimental concept and the operation of the satellite. Chapter 2 covers the
core cosmological science of the mission, describing the measurements that
Planck will make, what we expect to learn from them about the geometry and
contents of the Universe and about fundamental physics, and the combination of
CMB data with other data to provide additional insights. Although the primary
goal of Planck is cosmology, it will survey the whole sky with an unprecedented
combination of frequency coverage, angular resolution, and sensitivity,
providing data valuable for a broad range of astrophysics. Chapters 3, 4, and 5
describe non-cosmological astrophysical uses of the Planck data. This book can
also be downloaded directly from http://www.rssd.esa.int/Planck .


title:
Non-Gaussianity in the Very Small Array CMB maps with
  Smooth-Goodness-of-fit tests

abstract:
  (Abridged) We have used the Rayner & Best (1989) smooth tests of
goodness-of-fit to study the Gaussianity of the Very Small Array (VSA) data.
Out of the 41 published VSA individual pointings dedicated to cosmological
observations, 37 are found to be consistent with Gaussianity, whereas four
pointings show deviations from Gaussianity. In two of them, these deviations
can be explained as residual systematic effects of a few visibility points
which, when corrected, have a negligible impact on the angular power spectrum.
The non-Gaussianity found in the other two (adjacent) pointings seems to be
associated to a local deviation of the power spectrum of these fields with
respect to the common power spectrum of the complete data set, at angular
scales of the third acoustic peak (l = 700-900). No evidence of residual
systematics is found in this case, and unsubstracted point sources are not a
plausible explanation either. If those visibilities are removed, a cosmological
analysis based on this new VSA power spectrum alone shows no differences in the
parameter constraints with respect to our published results, except for the
physical baryon density, which decreases by 10 percent. Finally, the method has
been also used to analyse the VSA observations in the Corona Borealis
supercluster region (Genova-Santos et al. 2005), which show a strong decrement
which cannot be explained as primordial CMB. Our method finds a clear deviation
(99.82%) with respect to Gaussianity in the second-order moment of the
distribution, and which can not be explained as systematic effects. A detailed
study shows that the non-Gaussianity is produced in scales of l~500, and that
this deviation is intrinsic to the data (in the sense that can not be explained
in terms of a Gaussian field with a different power spectrum).


title: Dark energy parameterizations and their effect on dark halos

abstract:
  There is a plethora of dark energy parameterizations that can fit current
supernovae Ia data. However, this data is only sensitive to redshifts up to
order one. In fact, many of these parameterizations break down at higher
redshifts. In this paper we study the effect of dark energy models on the
formation of dark halos. We select a couple of dark energy parameterizations
which are sensible at high redshifts and compute their effect on the evolution
of density perturbations in the linear and non-linear regimes. Using the
Press-Schechter formalism we show that they produce distinguishable signatures
in the number counts of dark halos. Therefore, future observations of galaxy
clusters can provide complementary constraints on the behavior of dark energy.


title: Pulsar twinkling and relativity

abstract:
  The number of pulsars with detected emission at X-ray and gamma-ray energies
has been steadily growing, showing that beams of high-energy particles are
commonly accelerated in pulsar magnetospheres, even though the location and
number of acceleration sites remain unsettled. Acceleration near the magnetic
poles, close to the polar cap surface or to higher altitudes in the slot gap
along the last open field lines, involves an electric field component due to
inertial-frame dragging. Acceleration can also take place in the outer
magnetosphere where charge depletion due to global currents causes a large
electric field along the magnetic field lines. All models require a detailed
knowledge of the open magnetosphere geometry and its relativistic distortions.
Observational trends with age, spin-down power and magnetic field as well as
population synthesis studies in the Galactic disc and the nearby Gould Belt
provide useful, however not yet conclusive, constraints on the competing
models.


title:
Extending the redshift distribution of submm galaxies: Identification of
  a z~4 submm galaxy

abstract:
  We present the identification of a bright submillimeter galaxy (SMG) in the
field of Abell 2218. The galaxy has a spectroscopic redshift of ~4, and is
currently the highest redshift SMG known. It is detected at all wavelengths
from optical to submm, including the Spitzer IRAC bands. We discuss the
properties of this galaxy, which is undergoing intense star formation at a
rate~600 Msun/yr. We also compare the properties to those of radio-preselected
submm-bright galaxies. The z~4 result extends the redshift distribution of
SMGs.


title: Molecular Outflows in Galaxy Merger Simulations with Embedded AGN

abstract:
  We study the effects of feedback from active galactic nuclei (AGN) on
emission from molecular gas in galaxy mergers by combining hydrodynamic
simulations which include black holes with a three-dimensional, non-local
thermodynamic equilibrium (LTE) radiative transfer code. We find that molecular
clouds entrained in AGN winds produce an extended CO morphology with
significant off-nuclear emission, which may be detectable via contour mapping.
Furthermore, kinematic signatures of these molecular outflows are visible in
emission line profiles when the outflow has a large line of sight velocity. Our
results can help interpret current and upcoming observations of luminous
infrared galaxies, as well as provide a detailed test of subresolution
prescriptions for supermassive black hole growth in galaxy-scale hydrodynamic
simulations.


title:
Perturbation Theory Reloaded: Analytical Calculation of Non-linearity in
  Baryonic Oscillations in the Real Space Matter Power Spectrum

abstract:
  We compare the non-linear matter power spectrum in real space calculated
analytically from 3rd-order perturbation theory with N-body simulations at
1<z<6. We find that the perturbation theory prediction agrees with the
simulations to better than 1% accuracy in the weakly non-linear regime where
the dimensionless power spectrum, Delta^2(k)=k^3P(k)/2pi^2, which approximately
gives variance of matter density field at a given k, is less than 0.4. While
the baryonic acoustic oscillation features are preserved in the weakly
non-linear regime at z>1, the shape of oscillations is distorted from the
linear theory prediction. Nevertheless, our results suggest that one can
correct the distortion caused by non-linearity almost exactly. We also find
that perturbation theory, which does not contain any free parameters, provides
a significantly better fit to the simulations than the conventional approaches
based on empirical fitting functions to simulations. The future work would
include perturbation theory calculations of non-linearity in redshift space
distortion and halo biasing in the weakly non-linear regime.


title: A Debris Disk Around An Isolated Young Neutron Star

abstract:
  Pulsars are rotating, magnetized neutron stars that are born in supernova
explosions following the collapse of the cores of massive stars. If some of the
explosion ejecta fails to escape, it may fall back onto the neutron star or it
may possess sufficient angular momentum to form a disk. Such 'fallback' is both
a general prediction of current supernova models and, if the material pushes
the neutron star over its stability limit, a possible mode of black hole
formation. Fallback disks could dramatically affect the early evolution of
pulsars, yet there are few observational constraints on whether significant
fallback occurs or even the actual existence of such disks. Here we report the
discovery of mid-infrared emission from a cool disk around an isolated young
X-ray pulsar. The disk does not power the pulsar's X-ray emission but is
passively illuminated by these X-rays. The estimated mass of the disk is of
order 10 Earth masses, and its lifetime (at least a million years)
significantly exceeds the spin-down age of the pulsar, supporting a supernova
fallback origin. The disk resembles protoplanetary disks seen around ordinary
young stars, suggesting the possibility of planet formation around young
neutron stars.


title:
Predictions for the correlation between giant and terrestrial extrasolar
  planets in dynamically evolved systems

abstract:
  The large eccentricities of many giant extrasolar planets may represent the
endpoint of gravitational scattering in initially more crowded systems. If so,
the early evolution of the giant planets is likely to be more restrictive of
terrestrial planet formation than would be inferred from the current,
dynamically quiescent, configurations. Here, we study statistically the extent
of the anti-correlation between giant planets and terrestrial planets expected
in a scattering model. We use marginally stable systems of three giant planets,
with a realistic range of planetary masses, as a simple model for the initial
conditions prior to scattering, and show that after scattering the surviving
planets reproduce well the known extrasolar planet eccentricities beyond a >
0.5 AU. By tracking the minimum periastron values of all planets during the
evolution, we derive the distribution of orbital radii across which strong
perturbations (from crossing orbits) are likely to affect low mass planet
formation. We find that scattering affects inner planet formation at orbital
separations less than 50% of the final periastron distance of the innermost
massive planet in approximately 30% of the realizations, and can occasionally
influence planet formation at orbital separations less than 20% of the final
periastron distance of the innermost massive planet. The domain of influence of
the scattering massive planets increases as the mass differential between the
massive planets decreases. Observational study of the correlation between
massive and terrestrial extrasolar planets in the same system has the potential
to constrain the origin of planetary eccentricity.


title: Protoplanet Dynamics in a Shear-Dominated Disk

abstract:
  The velocity dispersion, or eccentricity distribution, of protoplanets
interacting with planetesimals is set by a balance between dynamical friction
and viscous stirring. We calculate analytically the eccentricity distribution
function of protoplanets embedded in a cold, shear-dominated planetesimal
swarm. We find a distinctly non-Rayleigh distribution with a simple analytical
form. The peak of the distribution lies much lower than the root-mean-squared
value, indicating that while most of the bodies have similarly small
eccentricities, a small subset of the population contains most of the thermal
energy. We also measure the shear-dominated eccentricity distribution using
numerical simulations. The numerical code treats each protoplanet explicitly
and adds an additional force term to each body to represent the dynamical
friction of the planetesimals. Without fitting any parameters, the eccentricity
distribution of protoplanets in the N-body simulation agrees with the
analytical results. This distribution function provides a useful tool for
testing hybrid numerical simulations of late-stage planet formation.


title: Shoemaker-Levy 9 Impact Modeling: I. High-Resolution 3D Bolides

abstract:
  We have run high-resolution, three-dimensional, hydrodynamic simulations of
the impact of comet Shoemaker-Levy 9 into the atmosphere of Jupiter. We find
that the energy deposition profile is largely similar to the previous
two-dimensional calculations of Mac Low and Zahnle (1994), though perhaps
somewhat broader in the range of height over which the energy is deposited. As
with similar calculations for impacts into the Venusian atmosphere, there is
considerable sensitivity in the results to small changes in the initial
conditions, indicating dynamical chaos. We calculated the median depth of
energy deposition (the height z at which 50% of the bolide's energy has been
released) per run. The mean value among runs is approx 70 km below the 1-bar
level, for a 1-km diameter impactor of porous ice of density rho=0.6 g cm^{-3}.
The standard deviation among these runs is 14 km. We find little evidence of a
trend in these results with the resolution of the calculations (up to 57 cells
across the impactor radius, or 8.8-m resolution), suggesting that resolutions
as low as 16 grid cells across the radius of the bolide may yield good results
for this particular quantity.


title: Redshifted 21 Centimeter Emission from Minihalos Before Reionization

abstract:
  Before reionization, the intergalactic medium (IGM) may have been
sufficiently cold for low-mass "minihalos" to condense out of the gas and
subsequently affect reionization. Previous work has shown that minihalos
generate reasonably large 21 cm fluctuations. Here we consider this signal in
its proper cosmological context and show that isolating minihalos from the rest
of the IGM is extremely difficult. Using the well-known halo model, we compute
the power spectrum of 21 cm fluctuations from minihalos and show that the
signal decreases rapidly as feedback increases the Jeans mass. We then show
that even a small Lyman-alpha background increases the 21 cm fluctuations of
the diffuse IGM well beyond those of the minihalos; because the mass fraction
in the IGM is much larger, minihalos will lie buried within the IGM signal. The
distinctive signatures of non-linear bias and minihalo structure emerge only at
much smaller scales, well beyond the resolution of any upcoming instruments.
Using simple, but representative, reionization histories, we then show that the
required Lyman-alpha background level is most likely achieved at z>15, while
minihalos are still rare, so that they are almost always degenerate with the
diffuse IGM.


title: Stellar Properties of Embedded Protostars

abstract:
  (Abridged) High dispersion spectrographs on large aperture telescopes have
recently allowed observers to study the stellar and accretion properties of
deeply embedded young stars, commonly referred to as Class I stars. We
summarize these newly determined properties and compare them with observations
of more optically revealed Class II (T Tauri) stars. Class I stars have
spectral types and stellar luminosities similar to those of Class II stars,
suggesting similar masses and ages. Estimates of stellar luminosity and age,
however, are especially uncertain given the large extinctions, scattered light
emission and continuum excesses typical of Class I stars. Several candidate
Class I brown dwarfs are identified. Class I stars appear to rotate more
rapidly than T Tauri stars, by roughly a factor of 2. Likewise, Class I disk
accretion rates are only a factor of two larger than those of T Tauri stars,
less than the mass infall rates predicted by envelope models by 1-2 orders of
magnitude. In at least a few cases the discrepancy appears to be caused by T
Tauri stars being misclassified as Class I stars because of their edge-on disk
orientation. Stars where the envelope density and infall velocity have been
determined directly and unambiguously imply that stellar mass is not acquired
in a steady-state fashion, but instead through brief outbursts of enhanced
accretion. If some Class I stars are in fact as old as T Tauri stars,
replenishment may be necessary to sustain the long-lived envelopes, possibly
via continued dynamical interactions with cloud material.


title:
Evolution of the Color-Magnitude relation in High-Redshift Clusters:
  Early-type Galaxies in the Lynx Supercluster at z~1.26

abstract:
  Color-magnitude relations have been derived in the clusters RX J0849+4452 and
RX J0848+4453 at z~1.26. The color-magnitude relation was determined from
Advanced Camera for Surveys imaging in the WFC F775W (i_775) and F850LP (z_850)
filters combined with ground-based spectroscopy. Early-type cluster candidates
have been identified according to the Postman et al. morphological
classification. In both clusters the bright red early-type population defines a
tight color-magnitude relation very similar in color, although the two clusters
present different X-ray luminosities and shapes, with RX J0849+4452 being three
times more X-ray luminous and more compact, and having a temperature two times
higher. The elliptical galaxy color-magnitude relations (CMR) in RX J0849+4452
and RX J0848+4453 show an intrinsic (i_775-z_850) color scatter of 0.026 +/-
0.012 mag and 0.024 +/- 0.015 mag, respectively, within 2 arcminutes (~1Mpc at
z=1.26) from the cluster X-ray emission centers. Simple modeling of the
scatters using stellar population models from Bruzual and Charlot, gives a mean
luminosity-weighted age t > 2.5 Gyr (z_f > 2.75). S0 galaxies follow the
elliptical CMR; they show larger scatters about the CMR.
  The intrinsic scatter decreases and the CMR slopes are steeper at smaller
radii, within both clusters. We conclude that old stellar populations in
cluster elliptical galaxies are already in place at z=1.26, both in the more
evolved cluster RX J0849+4452, and in its less evolved companion RX J0848+4453.
Even at a lookback time of 9 Gyr, in the early merging and buildup of massive
clusters, the bulk of the stellar content of the bright elliptical galaxy
population was in place - apparently formed some 2.5~Gyr earlier at z~3


title:
On the Early Time X-ray Spectra of Swift Afterglows I: Evidence for
  Anomalous Soft X-ray Emission

abstract:
  We have conducted a thorough and blind search for emission lines in >70 Swift
X-ray afterglows of total exposure ~10^7s. We find that most afterglows are
consistent with pure power-laws plus extinction. Significant outliers to the
population exist at the 5-10% level and have anomalously soft, possibly thermal
spectra. Four bursts are singled out via possible detections of 2-5 lines: GRBs
060218, 060202, 050822, and 050714B. Alternatively, a blackbody model with
kT~0.1-0.5 keV can describe the soft emission in each afterglow. The most
significant soft component detections in the full data set of ~2000 spectra
correspond to GRB060218/SN2006aj, with line significances ranging up to
\~20-sigma. A thermal plasma model fit to the data indicates that the flux is
primarily due to L-shell transitions of Fe at ~ solar abundance. We associate
(>4-sigma significant) line triggers in the 3 other events with K-shell
transitions in light metals. We favor a model where the possible line emission
in these afterglows arises from the mildly relativistic cocoon of matter
surrounding the GRB jet as it penetrates and exits the surface of the
progenitor star. The emitting material in each burst is at a similar distance
\~10^12--10^13 cm, a similar density ~10^17 cm^-3, and subject to a similar
flux of ionizing radiation. The lines may correlate with the X-ray flaring. For
the blackbody interpretation, the soft flux may arise from break out of the GRB
shock or plasma cocoon from the progenitor stellar wind, as recently suggested
for GRB060218 (Campana et al. 2006). Due to the low z of GRB060218, bursts
faint in Gamma-rays with fluxes dominated by this soft X-ray component could
outnumber classical GRBs 100-1.


title:
Einstein Field Equation: the Root of All Evil? Quantum Gravity, Solar
  Application and the Prediction on Gravity Probe B

abstract:
  The starting point of quantum mechanics is the relationship between energy
and momentum: energy is proportional to the squared momentum! As a result,
energy and momentum have not been treated equally. The wave equation required
by quantization is a differential equation which accordingly, does not treat
time and space equally. As a result, the Planck constant is not canceled out
from the two sides of the equation. Dr. He's gravity is the local bending of
background space-time which as suggested by Einstein, can be described by a
differential form of second order, and treats time and space equally.
Therefore, the Planck constant is completely canceled out in the resulting wave
equation. In other words, the quantization of gravity simply does not need the
Planck constant!


title:
Formation and evolution of compact binaries in globular clusters:
  I.Binaries with white dwarfs

abstract:
  In this paper, the first of a series, we study the stellar dynamical and
evolutionary processes leading to the formation of compact binaries containing
white dwarfs in dense globular clusters. We examine the processes leading to
the creation of X-ray binaries such as cataclysmic variables and AM CVn
systems. Using numerical simulations, we identify the dominant formation
channels and we predict the expected numbers and characteristics of detectable
systems, emphasizing how the cluster sources differ from the field population.
We explore the dependence of formation rates on cluster properties and we
explain in particular why the distribution of cataclysmic variables has only a
weak dependence on cluster density. We also discuss the frequency of dwarf nova
outbursts in globular clusters and their connection with moderately strong
white dwarf magnetic fields. We examine the rate of Type Ia supernovae via both
single and double degenerate channels in clusters and we argue that those rates
may contribute to the total SN Ia rate in elliptical galaxies. Considering
coalescing white dwarf binaries we discuss possible constraints on the common
envelope evolution of their progenitors and we derive theoretical expectations
for gravitational wave detection by LISA.


title: Black Hole Censorship of Varying Fundamental Constants

abstract:
  Here it is shown that the variation in the fine structure constant measured
by Webb et al. matches the theoretically derived value for the maximum
variation in the electronic charge permitted by the Generalized Second Law of
Thermodynamics for black holes accreting and emitting in the present cosmic
microwave background. It is postulated that the constants of nature,
independently or dependently, vary at the maximal rate allowed by the
Generalized Second Law of Thermodynamics.


title: A note on cosmological parameters and the topology of the universe

abstract:
  Given the wealth of increasingly accurate cosmological observations,
especially the recent results from the WMAP, and the development of methods and
strategies in the search for cosmic topology, it is reasonable to expect that
we should be able to detect the spatial topology of the Universe in the near
future. Motivated by this, we examine to what extent a possible detection of a
nontrivial topology of positively curved universe may be used to place
constraints on the matter content of the Universe. We show through concrete
examples that the knowledge of the spatial topology allows to place constraints
on the density parameters associated to dark matter ($\Omega_m$) and dark
energy ($\Omega_{\Lambda}$)


title:
Resolving Stellar Atmospheres I: The H alpha line and comparisons to
  microlensing observations

abstract:
  We present work on H alpha spectral line characteristics in PHOENIX stellar
model atmospheres and their comparison to microlensing observations. We examine
in detail the H alpha equivalent width (EW) and the line shape characteristics
for effective temperatures of 4500K< Teff < 5600K where H alpha is a strong
spectral feature. We find that H alpha EW in models calculated under the
assumption of local thermodynamic equilibrium (LTE) is up to 15% smaller than
in models without this assumption, non-LTE models (NLTE) and that line shapes
vary significantly for the two model types. A comparison with available high
quality microlensing data, capable of tracing H alpha absorption across the
face of one G5III giant, shows that the LTE model that fits the EW best is
about 100K hotter than and the best-fitting NLTE model has a similar Teff as
predicted by the spectral type analysis of the observed star but agree within
the uncertainties of the observationally derived temperature. Neither LTE nor
NLTE models fit the line shape well. We suspect unmodelled chromospheric
emission. Line shape diagnostics suggest lower gravities than derived for the
star and are unacceptable low in the case of the LTE models. We show that EW
alone is insufficient for comparison to stellar model atmospheres, but combined
with a new shape parameter we define is promising. In stellar parameter ranges
where the H alpha line is strong, a NLTE approach of modeling stellar
atmospheres is not only beneficial but mandatory.


title:
Searching for flickering variability in several symbiotic stars and
  related objects: BX Mon, V471 Per, RS Oph, V627 Cas, CI Cam V886 Her, Z And,
  T CrB, MWC 560, V407 Cyg

abstract:
  UBVRI photometry observations of 10 symbiotic stars and related objects
obtained in the period 2002-2003 are presented. Analysing differential light
curves we found rapid light variations with timescales of tens of minutes and
significant amplitudes in the well-known flickerers MWC 560, RS Oph, V407 Cyg
and T CrB. MWC 560 and V407 Cyg demonstrate quasi periodic oscillations (QPO)
with similar amplitudes and timescales. Flickering and unusual flare in V627
Cas as well as some indications of flickering presence in BX Mon are detected.
The existence of 29 minutes oscillations in Z And with an amplitude about 0.02
mag in U band is confirmed. Only one symbiotic star, V471 Per, and both non
symbiotic, CI Cam and V886 Her seem to be constant on flickering timescales.
Nevertheless, small night to night changes in the brightness of V886 Her were
observed as well.


title: Crossing the phantom barrier with purely kinetic multiple k-essence

abstract:
  We consider multiple k-essence sources and obtain the conditions their
kinetic functions must satisfy so that purely kinetic k-essences lead to models
with phantom barrier crossing. After that, we show that polynomial kinetic
functions allow the integration of the dynamical equations determining the
geometry and the k-fields. The models thus obtained have accelerated expansion
at late cosmic time, representing universes ending at a finite time with a big
rip singularity. In addition, these models begin to evolve from an initial
singularity, so they have a finite time span.


title: A Survey of O VI, C III, and H I in Highly Ionized High-Velocity Clouds

abstract:
  (ABRIDGED) We present a Far-Ultraviolet Spectroscopic Explorer survey of
highly ionized high-velocity clouds (HVCs) in 66 extragalactic sight lines. We
find a total of 63 high-velocity O VI absorbers, 16 with 21 cm-emitting H I
counterparts and 47 ``highly ionized'' absorbers without 21 cm emission. 11 of
these high-velocity O VI absorbers are positive-velocity wings (broad O VI
features extending asymmetrically to velocities of up to 300 km/s). The highly
ionized HVC population is characterized by <b(O VI)>=38+/-10 km/s and <log
N_a(O VI)>=13.83+/-0.36. We find that 81% (30/37) of high-velocity O VI
absorbers have clear accompanying C III absorption, and 76% (29/38) have
accompanying H I absorption in the Lyman series. The lower average width of the
high-velocity H I absorbers implies the H I lines arise in a separate, lower
temperature phase than the O VI. We find that the shape of the wing profiles is
well reproduced by a radiatively cooling, vertical outflow. However, the
outflow has to be patchy and out of ionization equilibrium. An alternative
model, consistent with the observations, is one where the highly ionized HVCs
represent the low N(H I) tail of the HVC population, with the O VI formed at
the interfaces around the embedded H I cores. Though we cannot rule out a Local
Group explanation, we favor a Galactic origin. This is based on the recent
evidence that both H I HVCs and the million-degree gas detected in X-ray
absorption are Galactic phenomena. Since the highly ionized HVCs appear to
trace the interface between these two Galactic phases, it follows that highly
ionized HVCs are Galactic themselves. However, the non-detection of
high-velocity O VI in halo star spectra implies that any Galactic high-velocity
O VI exists at z-distances beyond a few kpc.


title:
Curvelet analysis of asteroseismic data I: Method description and
  application to simulated sun-like stars

abstract:
  Context: The detection and identification of oscillation modes (in terms of
their $\ell$, $m$ and successive $n$) is a great challenge for present and
future asteroseismic space missions. The "peak tagging" is an important step in
the analysis of these data to provide estimations of stellar oscillation mode
parameters, i.e., frequencies, rotation rates, and further studies on the
stellar structure.
  Aims: To increase the signal-to-noise ratio of the asteroseismic spectra
computed from time series representative of MOST and CoRoT observations (30-
and 150-day observations).
  Methods: We apply the curvelet transform -- a recent image processing
technique which looks for curved patterns -- to echelle diagrams built using
asteroseismic power spectra. In this diagram the eigenfrequencies appear as
smooth continuous ridges. To test the method we use Monte Carlo simulations of
several sun-like stars with different combinations of rotation rates,
rotation-axis inclination and signal-to-noise ratios.
  Results: The filtered diagrams enhance the contrast between the ridges of the
modes and the background allowing a better tagging of the modes and a better
extraction of some stellar parameters. Monte Carlo simulations have also shown
that the region where modes can be detected is enlarged at lower and higher
frequencies compared to the raw spectra. Even more, the extraction of the mean
rotational splitting from modes at low frequency can be done more easily than
using the raw spectrum.


title: Physics of the GRB 030328 afterglow and its environment

abstract:
  We report on the photometric, spectroscopic and polarimetric, monitoring of
the optical afterglow of Gamma-Ray Burst (GRB) 030328 detected by HETE-2.
Photometry, collected at 7 different telescopes, shows that a smoothly broken
powerlaw decay, with indices alpha_1 = 0.76 +/- 0.03, alpha_2 = 1.50 +/- 0.07
and a break at t_b = 0.48 +/- 0.03 days after the GRB, provides the best fit of
the optical afterglow decline. This shape is interpreted as due to collimated
emission, for which we determine a jet opening angle theta_{jet} of about 3.2
degrees. An achromatic bump starting around 0.2 d after the GRB is possibly
marginally detected in the optical light curves. Optical spectroscopy shows the
presence of two rest-frame ultraviolet metal absorption systems at z = 1.5216
+/- 0.0006 and at z = 1.295 +/- 0.001, the former likely associated with the
GRB host galaxy. Analysis of the absorption lines at z = 1.5216 suggests that
the host of this GRB may be a Damped Lyman-alpha Absorber. The optical V-band
afterglow appears polarized, with P= (2.4 +/- 0.6) % and theta = (170 +/- 7)
degrees, suggesting an asymmetric blastwave expansion. An X-ray-to-optical
spectral flux distribution of the GRB 030328 afterglow was obtained at 0.78
days after the GRB and fitted using a broken powerlaw, with an optical spectral
slope beta_{opt} = 0.47 +/- 0.15, and an X-ray slope beta_{X} = 1.0 +/- 0.2.
The discussion of these results in the context of the "fireball model" shows
that the preferred scenario for this afterglow is collimated structured jet
with fixed opening angle in a homogeneous medium.


title:
New Technique for the Measurement of the Scintillation Efficiency of
  Nuclear Recoils

abstract:
  We present a new technique developed for the measurement of the scintillation
efficiency of nuclear recoils in solid scintillators. Using this technique we
measured the quenching of the scintillation efficiency for the various
recoiling nuclei in CaWO4 crystals which are used in direct Dark Matter
searches.


title:
Radio-Loudness of Active Galactic Nuclei: Observational Facts and
  Theoretical Implications

abstract:
  We investigate how the total radio luminosity of AGN-powered radio sources
depends on their accretion luminosity and the central black hole mass. Our
studies cover about seven orders of magnitude in accretion luminosity and the
full range of AGN black hole masses. We find that AGNs form two distinct and
well separated sequences on the radio-loudness -- Eddington-ratio plane. The
`upper' sequence is formed by radio selected AGNs, the `lower' sequence
contains mainly optically selected objects. Whereas an apparent `gap' between
the two sequences may be an artifact of selection effects, the sequences
themselves mark the real upper bounds of radio-loudness of two distinct
populations of AGNs: those hosted respectively by elliptical and disk galaxies.
Both sequences show the same dependence of the radio-loudness on the Eddington
ratio (an increase with decreasing Eddington ratio), which suggests that the
normalization of this dependence is determined by the black hole spin. This
implies that central black holes in giant elliptical galaxies have (on average)
much larger spins than black holes in spiral/disc galaxies. This
galaxy-morphology related radio-dichotomy breaks down at high accretion rates
where the dominant fraction of luminous quasars hosted by elliptical galaxies
is radio quiet. This led to speculations in the literature that formation of
powerful jets at high accretion rates is intermittent and related to switches
between two disk accretion modes, as directly observed in some BH X-ray
binaries. We argue that such intermittency can be reconciled with the spin
paradigm, provided that successful formation of relativistic jets by rotating
black holes requires collimation by MHD outflows from accretion disks.


title:
Connection between accretion disk and superluminal radio jets and the
  role of radio plateau state in GRS 1915+105

abstract:
  We investigate the association between the accretion disk during radio
plateau state and the following superluminal relativistic radio jets with peak
intensity varies from 200 mJy to 1000 mJy observed over a period of five years
and present the evidences of direct accretion disc-jet connection in
microquasar GRS 1915+105. We have analysed RXTE PCA/HEXTE X-ray data and have
found that the accretion rate, $\dot{m}_{accr}$, as inferred from the X-ray
flux, is very high during the radio plateaux. We suggest that the accretion
disk during the radio plateaux always associated with radiation-driven wind
which is manifested in the form of enhanced absorption column density for X-ray
and the depleted IR emission. We find that the wind density increases with the
accretion disk luminosity during the radio plateaux. The wind density is
similar to the density of the warm absorber proposed in extragalactic AGNs and
Quasars. We suggest a simple model for the origin of superluminal relativistic
jets. Finally, We discuss the implications of this work for galactic
microquasars and the extragalactic AGNs and Quasars.


title: The XMM-Newton view of the Crab

abstract:
  We discuss the current X-ray view of the Crab Nebula and Pulsar, summarising
our analysis of observations of the source with the EPIC-pn camera on board the
XMM-Newton observatory. Different modes of EPIC-pn were combined in order to
yield a complete scenario of the spectral properties of the Crab resolved in
space and time (pulse phase). In addition we give a description of the special
EPIC-pn Burst mode and guidance for data reduction in that mode.
  We analysed spectra for the nebula and pulsar separately in the 0.6-12.0 keV
energy band. All data were processed with the SAS 6.0.0 XMM-Newton Scientific
Analysis System package; models were fitted to the data with XSPEC 11. The high
time resolution of EPIC-pn in its Burst mode (7 micros) was used for a phase
resolved analysis of the pulsar spectrum, after determination of the period
with epoch folding techniques. Data from the Small Window mode were processed
and corrected for pile-up allowing for spectroscopy simultaneously resolved in
space and time.
  The spatial variation of the spectrum over the entire region of the Crab
shows a gradual spectral softening from the inner pulsar region to the outer
nebula region with a variation in photon index, Gamma, from 2.0 to 2.4. Pulse
phase resolved spectroscopy of the Crab Pulsar reveals a phase dependent
modulation of the photon index in form of a significant hardening of the
spectrum in the inter-peak phase from Gamma =1.7 during the pulse peak to Gamma
=1.5.


title: Mid-Infrared Images of Stars and Dust in Irregular Galaxies

abstract:
  We present mid-infrared to optical properties of 22 representative irregular
galaxies: 18 Im, 3 BCDs, and one Sm. The mid-IR is based on images from the
Spitzer Space Telescope archives. The 3.6 and 4.5 micron bands and the UBVJHK
images are used to examine disk morphology and the integrated and azimuthally
averaged magnitudes and colors of stars. The non-stellar contribution to the
4.5 micron images is used to trace hot dust. The 5.8 and 8.0 micron images
reveal emission from hot dust and PAHs, and both may contribute to these
passbands, although we refer to the non-stellar emission as PAH emission. We
compare the 8.0 micron images to Halpha. Im galaxies have no hidden bars, and
those with double-exponential optical light profiles have the same at mid-IR.
Most galaxies have similar optical mid-IR scale lengths. Four galaxies have
super star clusters that are not visible at optical bands. Galaxies with higher
area-normalized star formation rates have more dust and PAH emission relative
to starlight. Hot dust and PAH emission is found mostly in high surface
brightness HII regions, implying that massive stars are the primary source of
heating. Galaxies with intense, wide-spread star formation have more extended
PAH emssion. The ratio of PAH to Halpha emission is not constant on small
scales. PAHs are associated with shell and giant filaments, so they are not
destroyed during shell formation.