title:
Galaxy clustering from COMBO-17: The halo occupation distribution at
  <z>=0.6

abstract:
  We present measurements of galaxy clustering at redshift <z>=0.6 using 10360
galaxies with photometric redshifts over an area of 0.78 square degree from the
COMBO-17 survey. To obtain a result that is unaffected by redshift
uncertainties, we calculate the projected correlation function w(r_p), giving
results for red sequence and blue cloud galaxies separately. The correlation
function of the red galaxies displays clear deviations from a power law at
comoving separations around 1 to 3 h^-1 Mpc, and similar but weaker trends are
suggested by the data for the blue galaxies. To interpret these results, we fit
the correlation functions with analytical predictions derived from a simple
halo occupation model. This combines linear clustering of the underlying mass
with a description of the number of galaxies occupying each dark-matter halo
(the halo occupation distribution). If the occupation numbers are taken to be a
simple power law with N proportional to M^alpha, then alpha ~ 0.5 and alpha ~
0.2 for red and blue galaxies respectively. These figures are little different
from the values required to fit present-day clustering data. The power-spectrum
shape is assumed to be known in this exercise, but we allow the data to
determine the preferred value of sigma_8, the linear power-spectrum
normalization. The average normalization inferred from red and blue galaxies at
<z> =0.6 is sigma_8=1.02+-0.17 at zero redshift, consistent with independent
estimates of this local value. This agreement can be regarded as a verification
of the hierarchical growth of the halo mass function.


title: Radiative Transfer and Acceleration in Magnetocentrifugal Winds

abstract:
  Detailed photoionization and radiative acceleration of self-similar
magnetocentrifugal accretion disk winds are explored. First, a general-purpose
hybrid magnetocentrifugal and radiatively-driven wind model is defined.
Solutions are then examined to determine how radiative acceleration modifies
magnetocentrifugal winds and how those winds can influence radiative driving in
Active Galactic Nuclei (AGNs). For the models studied here, both radiative
acceleration by bound-free (``continuum-driving'') and bound-bound
(``line-driving'') processes are found to be important, although magnetic
driving dominates the mass outflow rate for the Eddington ratios studied
(L/L_Edd = 0.001 - 0.1). The solutions show that shielding by a
magnetocentrifugal wind can increase the efficiency of a radiatively-driven
wind, and also that, within a magnetocentrifugal wind, radiative acceleration
is sensitive to both the column in the shield, the column of the wind and the
initial density at the base of the wind.


title: Ion Heating in Collisionless Shocks in Supernovae and the Heliosphere

abstract:
  Collisionless shocks play a role in many astrophysical phenomena, from
coronal mass ejections (CMEs) in the heliosphere to supernova remnants. Their
role in heating and accelerating particles is well accepted yet the exact
mechanism for ion heating is not well understood. Two systems, CMEs and
supernova remnants, were examined to determine the heating of heavy ions as
they pass through collisionless shocks thus providing a seed population for
cosmic ray acceleration processes. Three parameters are examined, the plasma
beta, the Mach number of the shock and the magnetic angle of the shock. CMEs
heat heavy ions preferentially. This is in contrast to the supernova data which
shows less than mass proportional heating. In addition to these studies,
heating in astrophysical systems involves neutral atoms. A Monte Carlo model
simulated neutral particles as they pass through the shock. Neutrals can create
a precursor to the shock additionally heating the plasma. This work uses in
situ data from the heliosphere to study astronomical systems because of common
shock properties is a unique way to study magnetic components of shocks
remotely.


title:
The Ionized Gas and Nuclear Environment in NGC 3783 V. Variability and
  Modeling of the Intrinsic Ultraviolet Absorption

abstract:
  We present results on the location, physical conditions, and geometry of the
outflow in the Seyfert 1 galaxy NGC 3783 from a study of the variable intrinsic
UV absorption. Based on 18 observations with HST/STIS and 6 observations with
FUSE, we find: 1) The absorption from the lowest-ionization species in each of
the three strong kinematic components varied inversely with the continuum flux,
indicating the ionization structure responded to changes in the photoionizing
flux over the weekly timescales sampled by our observations. 2) A multi-
component model with an unocculted NLR and separate BLR and continuum
line-of-sight covering factors predicts saturation in several lines, consistent
with the lack of observed variability. 3) Column densities for the individual
metastable levels are measured from the resolved C III *1175 absorption complex
observed in one component. Based on our computed metastable level populations,
the electron density of this absorber is ~3x10^4 cm^-3. Photoionization
modeling results place it at ~25 pc from the central source. 4) Using
time-dependent calculations, we are able to reproduce the detailed variability
observed in this absorber, and derive upper limits on the distances for the
other components of 25-50 pc. 5) The ionization parameters derived for the
higher ionization UV absorbers are consistent with the modeling results for the
lowest-ionization X-ray component, but with smaller total column density. They
have similar pressures as the three X-ray ionization components. These results
are consistent with an inhomogeneous wind model for the outflow in NGC 3783. 6)
Based on the predicted emission-line luminosities, global covering factor
constraints, and distances derived for the UV absorbers, they may be identified
with emission- line gas observed in the inner NLR of AGNs. (abridged)


title: Near and Mid Infrared Observations of Ultracompact HII Regions

abstract:
  This review discussed near- and mid- infrared observations of ultracompact
(UC) HII regions. The importance of ISO mid-IR fine-structure nebular lines is
emphasised since only a small fraction of UCHII regions are observed directly
in the near-IR. The reliability of contemporary atmospheric models for such
indirect diagnostics is discussed, whilst a revised Spectral Type-Temperature
calibration is presented for Galactic O3 to B3 dwarfs. In particular,
fine-structure line derived properties of G29.96-0.02 differ from the direct
near-IR spectroscopic result and represents a serious discrepancy which needs
to be addressed. Mid-IR MSX and Spitzer imaging permits the identification of
those UCHII regions for which far-IR IRAS fluxes are reliable, relevant to the
single versus cluster nature of individual sources. High spatial resolution
imaging with ground-based 8m telescopes allows more direct tests, as recently
applied to G70.29+1.60. Finally, recent Spitzer mid-IR observations of Giant
HII regions are briefly discussed.


title:
Anti-correlated hard X-ray time lag in GRS 1915+105: evidence for a
  truncated accretion disc

abstract:
  Multi-wavelength observations of Galactic black hole candidate sources
indicate a close connection between the accretion disk emission and the jet
emission. The recent discovery of an anti-correlated time lag between the soft
and hard X-rays in Cygnus X-3 (Choudhury & Rao 2004) constrains the geometric
picture of the disk-jet connection into a truncated accretion disk, the
truncation radius being quite close to the black hole. Here we report the
detection of similar anti-correlated time lag in the superluminal jet source
GRS 1915+105. We show the existence of the pivoting in the X-ray spectrum
during the delayed anti-correlation and we also find that the QPO parameters
change along with the spectral pivoting. We explore theoretical models to
understand this phenomenon.


title:
On the accuracy of slow-roll inflation given current observational
  constraints

abstract:
  We investigate the accuracy of slow-roll inflation in light of current
observational constraints, which do not allow for a large deviation from scale
invariance. We investigate the applicability of the first and second order
slow-roll approximations for inflationary models, including those with large
running of the scalar spectral index. We compare the full numerical solutions
with those given by the first and second order slow-roll formulae. We find that
even first order slow-roll is generally accurate; the largest deviations arise
in models with large running where the error in the power spectrum can be at
the level of 1-2%. Most of this error comes from inaccuracy in the calculation
of the slope and not of the running or higher order terms. Second order
slow-roll does not improve the accuracy over first order. We also argue that in
the basis $\epsilon_0=1/H$, $\epsilon_{n+1}={d\ln|\epsilon_n|}/{dN}$,
introduced by Schwarz et al. (2001), slow-roll does not require all of the
parameters to be small. For example, even a divergent $\epsilon_3$ leads to
finite solutions which are accurately described by a slow-roll approximation.
Finally, we argue that power spectrum parametrization recently introduced by
Abazaijan, Kadota and Stewart does not work for models where spectral index
changes from red to blue, while the usual Taylor expansion remains a good
approximation.


title:
The IMF in Extreme Star-Forming Environments: Searching for Variations
  vs. Initial Conditions

abstract:
  Any predictive theory of star formation must explain observed variations (or
lack thereof) in the initial mass function. Recent work suggests that we might
expect quantitative variations in the IMF as a function of metallicity (Larson
2005) or magnetic field strength (Shu et al. 2004). We summarize results from
several on-going studies attempting to constrain the ratio of high to low mass
stars, as well as stars to sub- stellar objects, in a variety of different
environments, all containing high mass stars.
  First, we examine the ratio of stars to sub--stellar objects in the nearby
Mon R2 region utilizing NICMOS/HST data. We compare our results to the IMF by
Kroupa (2002)]} and to the observed ratios for IC 348 and Orion. Second, we
present preliminary results for the ratio of high to low mass stars in W51, the
most luminous HII region in the galaxy. Based on ground--based multi--colour
images of the cluster obtained with the MMT adaptive optics system, we derive a
lower limit to the ratio of high-mass to low-mass stars and compare it to the
ratios for nearby clusters.
  Finally, we present the derived IMF for the R136 region in the LMC where the
metallicity is 1/4 solar using HST/NICMOS data. We find that the IMF is
consistent with that characterizing the field (Chabrier 2003), as well as
nearby star--forming regions, down to 1.0 Msun outside 2 pc. Whereas the
results for both Mon R2 and R136 are consistent with the nearby clusters, the
ratio of high to low mass stars in W51 tentatively indicates a lack of
low--mass objects.


title: Study of 23 day periodicity of Blazar Mkn501 in 1997

abstract:
  We confirm a 23 day periodicity during a large flare in 1997 for X-ray data
of X-ray satellite RXTE all sky monitor(ASM), 2 TeV gamma ray data from Utah
Seven Telescope and HEGRA, with a Fourier analysis. We found the three results
to be the same with a newly estimated error. We confirm the presence of a
frequency dependent power (1/f noise) in a frequency-power diagram. Further, we
calculated a chance probability of the occurrence of the 23 day periodicity by
considering the 1/f noise and obtained a chance probability 4.88*10^-3 for the
HEGRA data: this is more significant than previous result by an order. We also
obtained an identical peridoicity with another kind of timing analysis-epoch
folding method for the ASM data and HEGRA data. We strongly suggest an
existence of the periodicity. We divided the HEGRA data into two data sets,
analyzed them with a Fourier method, and found an unstableness of the
periodicity with a 3.4 sigma significance. We also analyzed an energy spectra
of the X-ray data of a RXTE proportional counter array and we found that a
combination of three parameters-a magnetic field, a Lorentz factor, and a
beaming factor-is related to the periodicity.


title: WIMPs search by means of the highly segmented scintillator

abstract:
  The highly sensitive method to search for WIMPs dark matter particles is
proposed. An array of thin NaI(Tl) plate has the great selectivity for
distinguishing the WIMPs events and background ones. The principle of signal
selection for WIMPs is described. The high sensitivity for SD (spin-dependent)
type WIMPs is expected by applying multi-layer system of NaI(Tl) detector.


title: Pioneer Anomaly and the Kuiper Belt mass distribution

abstract:
  Pioneer 10 and 11 were the first probes sent to study the outer planets of
the Solar System and Pioneer 10 was the first spacecraft to leave the Solar
System. Besides their already epic journeys, Pioneer 10 and 11 spacecraft were
subjected to an unaccounted effect interpreted as a constant acceleration
toward the Sun, the so-called Pioneer anomaly. One of the possibilities put
forward for explaining the Pioneer anomaly is the gravitational acceleration of
the Kuiper Belt. In this work we examine this hypothesis for various models for
the Kuiper Belt mass distribution. We find that the gravitational effect due to
the Kuiper Belt cannot account for the Pioneer anomaly. Furthermore, we have
also studied the hypothesis that drag forces can explain the the Pioneer
anomaly; however we conclude that the density required for producing the
Pioneer anomaly is many orders of magnitude greater than those of
interplanetary and interstellar dust. Our conclusions suggest that only through
a mission, the Pioneer anomaly can be confirmed and further investigated. If a
mission with these aims is ever sent to space, it turns out, on account of our
results, that it will be also a quite interesting probe to study the mass
distribution of the Kuiper Belt.


title:
Chandra Observations of A Galactic Supernova Remnant Vela Jr.: A New
  Sample of Thin Filaments Emitting Synchrotron X-Rays

abstract:
  A galactic supernova remnant (SNR) Vela Jr. (RX J0852.0$-$4622, G266.6$-$1.2)
shows sharp filamentary structure on the north-western edge of the remnant in
the hard X-ray band. The filaments are so smooth and located on the most outer
side of the remnant. We measured the averaged scale width of the filaments
($w_u$ and $w_d$) with excellent spatial resolution of {\it Chandra}, which are
in the order of the size of the point spread function of {\it Chandra} on the
upstream side and 49.5 (36.0--88.8) arcsec on the downstream side,
respectively. The spectra of the filaments are very hard and have no line-like
structure, and were well reproduced with an absorbed power-law model with
$\Gamma = $2.67 (2.55--2.77), or a {\tt SRCUT} model with $\nu_{rolloff}$ = 4.3
(3.4--5.3)$\times 10^{16}$ Hz under the assumption of $p=0.3$. These results
imply that the hard X-rays are synchrotron radiation emitted by accelerated
electrons, as mentioned previously. Using a correlation between a function
${\cal B} \equiv \nu_{rolloff}/w_d^2$ and the SNR age, we estimated the
distance and the age of Vela Jr.: the estimated distance and age are 0.33
(0.26--0.50) kpc and 660 (420--1400) years, respectively. These results are
consistent with previous reports, implying that ${\cal B}$--age relation may be
a useful tool to estimate the distance and the age of synchrotron X-ray
emitting SNRs.


title:
Extinction law variations and dust excitation in the spiral galaxy NGC
  300

abstract:
  We investigate the origin of the strong radial gradient in the
ultraviolet-to-infrared ratio in the spiral galaxy NGC 300, and emphasize the
importance of local variations in the interstellar medium geometry, concluding
that they cannot be neglected with respect to metallicity effects. This
analysis is based upon a combination of maps from GALEX and Spitzer, and from
the ground (UBVRI, Halpha and Hbeta). We select ionizing stellar clusters
associated with HII regions of widely varying morphologies, and derive their
fundamental parameters from population synthesis fitting of their spectral
energy distributions, measured to eliminate local backgrounds accurately. From
these fits, we conclude that the stellar extinction law is highly variable in
the line of sight of young clusters of similar ages. In the particular model
geometry that we consider most appropriate to the sampled regions, we checked
that our findings are not significantly altered by the correct treatment of
radiative transfer effects. The variations are systematic in nature: extinction
laws of the Milky Way or LMC type are associated with compact HII regions (the
compacity being quantified in two different ways), while clusters surrounded by
diffuse HII regions follow extinction laws of the 30 Doradus or SMC type. The
Calzetti starburst attenuation law, although most often degenerate with the 30
Doradus extinction law, overpredicts ionizing photon fluxes by large amounts.
We also find that the extinction law variations are correlated with the column
density of dust species emitting in the near- and mid-infrared. Finally, we
briefly discuss the nebular to stellar extinction ratios, and the excitation of
aromatic band carriers, invalidating their claimed association with cold dust.


title:
On the effective particle acceleration in the paraboloidal magnetic
  field

abstract:
  The problem of the efficiency of particle acceleration for parabolic poloidal
magnetic field is considered within the approach of steady axisymmetric MHD
flow. For the large Michel magnetization parameter it is possible to linearize
the stream equation near the force-free solution and to solve the problem
self-consistently as was done by Beskin, Kuznetsova and Rafikov (1998) for
monopole magnetic field. It is shown that on the fast magnetosonic surface the
particle Lorentz factor does not exceed the standard value. On the other hand,
in the supersonic region the Lorentz factor grows linearly with the distance
from the rotational axis, reaching almost its maximal value. This corresponds
to almost the full conversion of the Poynting energy flux into the particle
kinetic one.


title: Cosmological perturbations in multiple-field inflation

abstract:
  We analyze cosmological perturbations to the linear order in the context of
inflation with an arbitrary number of scalar fields. The fields take values on
a non-trivial manifold with a positive-definite metric and are non-minimally
coupled to Einstein gravity. The perturbations are decomposed into three
different types. The scalar-type perturbations are presented in a gauge-ready
form without fixing the temporal gauge condition, as well as in terms of
gauge-invariant variables. The gauge-ready method enables us to impose
different gauge conditions which are most suitable to the problem at hand. We
quantize the scalar perturbations and obtain the solutions.


title: Likelihood Estimation of Gamma Ray Bursts Duration Distribution

abstract:
  Two classes of Gamma Ray Bursts have been identified so far, characterized by
T90 durations shorter and longer than approximately 2 seconds. It was shown
that the BATSE 3B data allow a good fit with three Gaussian distributions in
log T90. In the same Volume in ApJ. another paper suggested that the third
class of GRBs is may exist. Using the full BATSE catalog here we present the
maximum likelihood estimation, which gives us 0.5% probability to having only
two subclasses. The MC simulation confirms this probability.


title:
Hot Stars in Old Stellar Populations: A Continuing Need for Intermediate
  Ages

abstract:
  We investigate the effect of a small contamination of hot, old, metal-poor
starlight on the inferred stellar populations of early-type galaxies in the
core of the Coma Cluster. We find that the required correction to the Balmer
and metal absorption-line strengths for old, metal-poor stars does not
significantly affect the inferred age of the stellar population when the Hbeta
strength is large. Intermediate-aged populations are therefore still needed to
explain enhanced Balmer-line strengths in early-type galaxies. This gives us
increased confidence in our age estimates for these objects. For galaxies with
weak Balmer-line strengths corresponding to very old populations (t>10 Gyr),
however, a correction for hot stars may indeed alter the inferred age, as
previously suggested. Finally, the inferred metallicity [Z/H] will always be
higher after any correction for old, metal-poor starlight than without, but the
enhancement ratios [E/Fe] will strengthen only slightly.


title: Emission line variability of RS Ophiuchi

abstract:
  We report that the H_alpha emission line of RS Oph was strongly variable
during our 2004 observations on a time scale of 1 month. The line consisted of
both a double peaked central narrow component (FWHM ~ 220 km/s) and a strongly
variable broad one (FWHM ~ 2000 km/s). The base of the H_alpha line was very
broad with FWZI 4600 km/s on all spectra from 1986 to 2004. The variability of
the broad component extends from -2000 to +2000 km/s. Most probably this is due
to either blobs ejected from the white dwarf (with a typical blob mass
estimated to be ~10^{-10} M_solar or a variable accretion disk wind.
  We also detected variability of the HeII4686 line on a time scale shorter
than 1 day. The possible origin is discussed.


title: Mira Variables in the OGLE Bulge fields

abstract:
  (abridged) The 222000 I-band light curves of variable stars detected by the
OGLE-II survey in the direction of the Galactic Bulge have been fitted and have
also been correlated with the DENIS and 2MASS databases. Results are presented
for 2691 objects with I-band semi-amplitude larger than 0.45 magnitude,
corresponding to classical Mira variables. The Mira period distribution of 6
fields at similar longitude but spanning latitudes from -1.2 to -5.8 degrees
are statistically indistinguisable indicating similar populations with initial
masses of 1.5-2 \msol (corresponding to ages of 1-3 Gyr). A field at similar
longitude at b = -0.05 from Glass et al. (2001) does show a significantly
different period distribution, indicating the presence of a younger population
of 2.5-3 \msol and ages below 1 Gyr. The K-band period-luminosity relation is
presented for the whole sample, and for sub-fields. The zero point depends on
Galactic longitude. Simulations are carried out to show that the observed
dependence of the zero point with $l$, and the number of stars per field are
naturally explained using the model of disk and bulge stars of Binney et al.
(1997), for a viewing angle of 43 +/- 17 degrees. A comparison is made with
similar objects in the Magellanic Clouds, studied in a previous paper. The
slope of the PL-relation in the Bulge and the MCs agree within the errorbars. A
distance to the Galactic Centre between 8.6 and 9.0 kpc is derived (for an
assumed DM of 18.50 to the LMC).


title:
The supernova rate-velocity dispersion relation in the interstellar
  medium

abstract:
  We investigate the relationship between the velocity dispersion of the gas
and the SN rate and feedback efficiency in the ISM. We explore the constancy of
the velocity dispersion profiles in the outer parts of galactic disks at~6-8 km
s^-1, and the transition to the starburst regime. Our results show that a) SN
driving leads to constant velocity dispersions of sig~6 km s^-1 for the total
gas and sigHI~3 km s^-1 for the HI gas, independent of the SN rate, for values
of the rate between 0.01-0.5 the Galactic rate R_{G},b) the position of the
transition to the starburst regime at SFR/Area~5*10^-3-10^-2 M_sol yr^-1 kpc^-2
observed in the simulations, is in good agreement with the transition to the
starburst regime in the observations, c) for the high SN rates, no HI gas is
present in the simulations box, however, for the total gas velocity dispersion,
there is good agreement between the models and the observations,d) at the
intermediate SN rates R/R_{G}~0.5-1, taking into account the thermal broadening
of the HI line helps reach a good agreement in that regime between the models
and the observations,e) for R/R_{G}<0.5, sig and sigHI fall below the observed
values by a factor of~2. However, a set of simulation with different values of
epsilon indicates that for larger values of the supernova feedback
efficiencies, velocity dispersions of the HI gas of the order of 5-6 km s^{-1}
can be obtained, in closer agreement with the observations. The fact that for
R/R_{G}<0.5, the HI gas velocity dispersions are a factor ~2 smaller than the
observed values could result from the fact that we might have underestimated
the SN feedback efficiency. It might also be an indication that other physical
processes couple to the stellar feedback in order to produce the observed level
of turbulence in galactic disks.


title:
Estimating the Porosity of the Interstellar Medium from
  Three-Dimensional Photoionization Modeling of H II Regions

abstract:
  We apply our three dimensional photoionization code to model Wisconsin
H-alpha Mapper observations of the H II region surrounding the O9.5V star Zeta
Oph. Our models investigate the porosity of the interstellar medium around zeta
Oph and the effects of 3D densities on the H-alpha surface brightness and
variation in the [N II]/H-alpha line ratio. The Zeta Oph H II region has a well
characterized ionizing source, so it is an excellent starting point for 3D
models of diffuse ionized gas. We investigate various hierarchically clumped
density structures, varying the overall smoothness within the clumping
algorithm. By simulating the observations, we can estimate the porosity of the
medium in the vicinity of Zeta Oph and find that within the context of our
hierarchically clumped models, around 50% to 80% of the volume is occupied by
clumps surrounded by a low density smooth medium. We also conclude that in
order for O stars to ionize the diffuse Warm Ionized Medium, the O star
environment must be more porous than that surrounding Zeta Oph, with clumps
occupying less than one half of the interstellar volume. Our clumpy models have
irregular boundaries, similar to observed H II regions. However, in observed H
II regions it is difficult to identify the precise location of the boundary
because of the foreground and/or background emission from the widespread Warm
Ionized Medium. This complicates the interpretation of the predicted rapid rise
of some emission line ratios near the edge of uniform density H II regions and
combined with the three dimensional clumpy nature of the interstellar medium
may explain the apparent lack of distinctive emission line ratios near H I -- H
II interfaces.


title: The Ultraluminous X-ray Sources NGC 1313 X-1 and X-2

abstract:
  We present a detailed analysis of XMM archival data of two Ultraluminous
X-ray Sources (ULXs) in the nearby spiral galaxy NGC 1313: NGC 1313 X-1 and
X-2. The spectral continuum of these sources was modeled with a soft thermal
component plus a power-law. If the soft component originates from an accretion
disk, the inferred mass of the compact remnant is > 100 M_sun, making it an
Intermediate Mass Black Hole (IMBH). A detailed analysis of the residuals of
the XMM EPIC-pn spectrum shows some evidence for the presence of an Oxygen
emission line in NGC 1313 X-1. The simultaneous presence of an excess in
emission, although at a much reduced significance level, at different energies
in the X-ray spectra of NGC 1313 X-1 and X-2 is suggestive of typical emission
lines from young supernova remnants. An optical counterpart for NGC 1313 X-2
was also identified. On an ESO 3.6 m image, the Chandra error box embraces a R
\~ 23 mag stellar-like object and excludes a previously proposed optical
counterpart.


title:
Dynamical and Pressure Structures in Winds with Multiple Embedded
  Evaporating Clumps I. 2D Numerical Simulations

abstract:
  Because of its key role in feedback in star formation and galaxy formation,
we examine the nature of the interaction of a flow with discrete sources of
mass injection. We show the results of two-dimensional numerical simulations in
which we explore a range of configurations for the mass sources and study the
effects of their proximity on the downstream flow. The mass sources act
effectively as a single source of mass injection if they are so close together
that the ratio of their combined mass injection rate is comparable to or
exceeds the mass flux of the incident flow into the volume that they occupy.
The simulations are relevant to many diffuse sources, such as planetary nebulae
and starburst superwinds, in which a global flow interacts with material
evaporating or being ablated from the surface of globules of cool, dense gas.


title:
A Spectroscopic Search for the non-nuclear Wolf-Rayet Population of the
  metal-rich spiral galaxy M83

abstract:
  We present a catalogue of non-nuclear regions containing Wolf-Rayet stars in
the metal-rich spiral galaxy M83 (NGC5236). From a total of 283 candidate
regions identified using HeII 4686 imaging with VLT-FORS2, Multi Object
Spectroscopy of 198 regions was carried out, confirming 132 WR sources. From
this sub-sample, an exceptional content of 1035 +/- 300 WR stars is inferred,
with N(WC)/N(WN) approx 1.2, continuing the trend to larger values at higher
metallicity amongst Local Group galaxies, and greatly exceeding current
evolutionary predictions at high metallicity. Late-type stars dominate the WC
population of M83, with N(WC8-9)/N(WC4-7)=9 and WO subtypes absent, consistent
with metallicity dependent WC winds. Equal numbers of late to early WN stars
are observed, again in contrast to current evolutionary predictions. Several
sources contain large numbers of WR stars. In particular, #74 (alias region 35
from De Vaucouleurs et al. contains 230 WR stars, and is identified as a Super
Star Cluster from inspection of archival HST/ACS images. Omitting this
starburst cluster would result in revised statistics of N(WC)/N(WN) approx 1
and N(WC8-9)/N(WC4-7) approx 6 for the `quiescent' disk population. Including
recent results for the nucleus and accounting for incompleteness in our
spectroscopic sample, we suspect the total WR population of M83 may exceed 3000
stars.


title: A comparative analysis of empirical calibrators for nebular metallicity

abstract:
  We present a new analysis of the main empirical calibrators of oxygen
abundance for ionised gas nebulae. With that aim we have compiled an extensive
sample of objects with emission line data including the near IR [SIII] lines
and the weak auroral lines which allow for the determination of the gas
electron temperature. For all the objects the oxygen abundances have been
derived in a homogeneus way, using the most recent sets of atomic coefficients
and taking into the account the effect of particle density on the temperature
of O$^+$. The residuals between directly and empirically-derived abundances as
a function of abundance have been studied. A grid of photo-ionisation models,
covering the range of physical properties of the gas, has been used to explain
the origin of the uncertainties affecting each abundance calibrator. The range
of validity for each abundance parameter has been identified and its average
uncertainty has been quantified.


title:
The Dark Halo of NGC 5963 as a Constraint on Dark Matter
  Self-Interaction at the Low Velocity Regime

abstract:
  Self-interacting dark matter has been proposed as a hypothesis to explain the
shallow central slopes of the density profiles of dark matter halos in
galaxies. In order to be consistent with observational studies at scales of
galaxy clusters, the cross section should scale inversely with the velocity of
collision. In this paper we consider the mass density profile of the halo of
the low surface brightness (LSB) galaxy NGC 5963 to place an upper limit on the
dark matter cross section for collisions with velocities $\sim 150$ km
s$^{-1}$, i.e. at the low velocity regime. After calibrating against
cosmological simulations, we found that the large inferred dark matter
concentration and central dark matter density in NGC 5963 are inconsistent with
an effective collisional cross section per unit of mass >0.2 cm^2/g.
Corrections were applied in order to account for reduction of the core by the
adiabatic contraction caused by cooling baryons. Our limits that involve a
number of simplifying, but always conservative, assumptions, exclude the last
permitted interval for velocity-dependent cross sections to explain the flat
density core in LSB galaxies. Implications for the nature of dark matter are
also discussed.


title: Constraints on hot metals in the Vicinity of the Galaxy

abstract:
  We have searched for evidence of soft X-ray absorption by hot metals in the
vicinity of the Galaxy in the spectra of a small sample of fifteen Type I AGN
observed with the high resolution X-ray gratings on board Chandra. This is an
extension of our previous survey of hot OVII and OVIII absorbing gas in the
vicinity of the Galaxy. The strongest absorption signatures within a few
hundred km/s of their rest-frame energies are most likely due to warm absorbing
outflows from the nearest AGN, which are back-lighting the local hot gas. We
emphasize that absorption signatures in the spectra of some distant AGN that
are kinematically consistent with the recessional velocity of the AGN are most
likely to be due to hot local gas. Along the sightline towards PG 1211+143, PDS
456 and MCG-6-30-15 there is a very large absorbing Fe column density which is
kinematically consistent with absorption by hot, local Fe. The sightlines to
these three AGN pass through the limb of the Northern Polar Spur (NPS), a local
bubble formed from several supernovae which, if rich in Fe, may account for a
large local Fe column.
  We obtain limits on the column density of local, highly ionized N, Ne, Mg, Si
along all of the sightlines in our sample. We correlate the column density
limits with those of highly ionized O along the same sightlines. Assuming the
hot local gas is in collisionally ionized equilibrium, we obtain limits on the
temperature and relative abundances of the metals in the hot local gas. Our
limits on the ionic column densities in the local hot gas seem to be consistent
with those observed in the hot halo gas of edge-on normal spiral galaxies.


title:
Stellar evolution with rotation and magnetic fields:III: The interplay
  of circulation and dynamo

abstract:
  We examine the effects of the magnetic field created by the Tayler--Spruit
dynamo in differentially rotating stars. Magnetic fields of the order of a few
$10^4$ G are present through most of the stellar envelope, with the exception
of the outer layers. The diffusion coefficient for the transport of angular
momentum is very large and it imposes nearly solid body rotation during the MS
phase. In turn, solid body rotation drives meridional circulation currents
which are much faster than usual and leads to much larger diffusion
coefficients than the magnetic diffusivity for the chemical species. The
consequence is that the interplay of the thermal and magnetic instabilities
favours the chemical transport of elements, while there would be no transport
in models with magnetic field only. We also discuss the effects on the stellar
interior, lifetimes and HR diagram.


title:
[Fe/H] relations for c-type RR Lyrae Variables based upon Fourier
  Coefficients

abstract:
  [Fe/H] - phi_31 - log P relations are found for c-type RR Lyrae stars in
globular clusters. The relations are analogous to that found by Jurcsik &
Kovacs (1996) for field ab-type RR Lyrae stars, where a larger period
correlates with lower metallicity values for similar values of the Fourier
coefficient phi_31. The relations obtained here are used to determine the
metallicity of field c-type RR Lyrae stars, those within omega Cen, the LMC and
toward the galactic bulge. The results are found to compare favorably to
metallicity values obtained elsewhere.


title:
Gravoturbulent Star Formation: Effects of the Equation of State on
  Stellar Masses

abstract:
  Stars form by gravoturbulent fragmentation of interstellar gas clouds. The
supersonic turbulence ubiquitously observed in Galactic molecular gas generates
strong density fluctuations with gravity taking over in the densest and most
massive regions. Collapse sets in to build up stars and star clusters.
  Turbulence plays a dual role. On global scales it provides support, while at
the same time it can promote local collapse. Stellar birth is thus intimately
linked to the dynamic behavior of parental gas clouds, which governs when and
where protostellar cores form, and how they contract and grow in mass via
accretion from the surrounding cloud material to build up stars. The equation
of state plays a pivotal role in the fragmentation process. Under typical cloud
conditions, massive stars form as part of dense clusters following the "normal"
mass function observed, e.g. in the solar neighborhood. However, for gas with
an effective polytropic index greater than unity star formation becomes biased
towards isolated massive stars. This is relevant for understanding the
properties of zero-metallicity stars (Population III) or stars that form under
extreme environmental conditions like in the Galactic center or in luminous
starbursts.


title:
Runaway electromagnetic cascade in shear flows and high energy radiation
  of astrophysical jets

abstract:
  We propose a straightforward and efficient mechanism of the high energy
emission of astrophysical jets associated with an exchange of interacting high
energy photons between the jet and external environment and vice versa.
Interactions which play the main role in this mechanism, are e^+ e^- pair
production by photons and inverse Compton scattering. The process has been
studied with numerical simulations demonstrating that under reasonable
conditions it has a supercritical character: high energy photons breed
exponentially being fed directly by the bulk kinetic energy of the jet.
Eventually, there is a feedback of particles on the fluid dynamics and the jet
partially decelerates.


title: The masses, radii and luminosities of the components of U Geminorum

abstract:
  We present a phase-resolved spectroscopic study of the secondary star in the
cataclysmic variable U Gem. We use our data to measure the radial velocity
semi-amplitude, systemic velocity and rotational velocity of the secondary
star. Combining this with literature data allows us to determine masses and
radii for both the secondary star and white dwarf which are independent of any
assumptions about their structure. We use these to compare their properties
with those of field stars and find that both components follow field
mass-radius relationships. The secondary star has the mass, radius, luminosity
and photometric temperature of an M2 star, but a spectroscopic temperature of
M4. The latter may well be due to a high metallicity. There is a troubling
inconsistency between the radius of the white dwarf inferred from its
gravitational redshift and inclination and that inferred from its temperature,
flux, and astrometric distance.
  We find that there are two fundamental limits to the accuracy of the
parameters we can derive. First the radial velocity curve of the secondary star
deviates from a sinusoid, in part because of its asphericity (which can be
modelled) and in part because the line flux is not evenly distributed over its
surface. Second we cannot be certain which spectral type is the best match for
the lines of the secondary star, and the derived rotational velocity is a
function of the spectral type of the template star used.


title:
Constraints on Inner Disk Evolution Timescales: A Disk Census of the eta
  Chamaeleontis Young Cluster

abstract:
  We present new L' (3.8-micron) observations of stars in the nearby (~97 pc)
young (~6 Myr) compact cluster around eta Chamaeleontis, obtained with the
European Southern Observatory's Very Large Telescope in Paranal, Chile. Our
data, combined with J,H, Ks photometry from the 2-Micron All Sky Survey, reveal
that only two of the 12 members surveyed harbor L'-band excesses consistent
with optically thick inner disks; both are also likely accretors. Intriguingly,
two other stars with possible evidence for on-going accretion, albeit at very
low rates, do not show significant infrared excess: this may imply substantial
grain growth and/or partial clearing of the inner disk region, as expected in
planet formation scenarios. Our findings suggest that eta Cha stars are in an
epoch when disks are rapidly evolving, perhaps due to processes related to
planet building, and provide further constraints on inner disk lifetimes.


title:
The X-ray binary population in M33: I. Source list and luminosity
  function

abstract:
  In this paper we present the source list for 3 Chandra observations of the
Local Group galaxy M33. The observations are centered on the nucleus and on the
star forming region NGC 604. We detect a total of 261 sources in an area of
\~0.2 square degree down to a flux limit of 3*10^{-16} erg/s/cm^2 which
corresponds to a luminosity of ~2*10^34 erg/s at a distance of 840 kpc. From
the source list we construct the luminosity functions of sources observed in
M33. Taking into account background contamination the luminosity functions are
consistent with those of other star forming galaxies. In addition, the
combination of X-ray color analysis and the existence of ``blue'' optical
counterparts strongly indicate that the X-ray point source population in M33
consists of young objects. Above 3*10^35 erg/s there are few X-ray sources in
the locus of the X-ray hardness ratio diagram that is generally populated by
LMXBs.


title: All-sky Relative Opacity Mapping Using Night Time Panoramic Images

abstract:
  An all-sky cloud monitoring system that generates relative opacity maps over
many of the world's premier astronomical observatories is described.
Photometric measurements of numerous background stars are combined with
simultaneous sky brightness measurements to differentiate thin clouds from sky
glow sources such as air glow and zodiacal light. The system takes a continuous
pipeline of all-sky images, and compares them to canonical images taken on
other nights at the same sidereal time. Data interpolation then yields
transmission maps covering almost the entire sky. An implementation of this
system is currently operating through the Night Sky Live network of CONCAM3s
located at Cerro Pachon (Chile), Mauna Kea (Hawaii), Haleakala (Hawaii), SALT
(South Africa) and the Canary Islands (Northwestern Africa).


title:
An unexpectedly rapid decline in the X-ray afterglow emission of long
  gamma-ray bursts

abstract:
  Long gamma-ray bursts (GRBs) are commonly accepted to originate in the
explosion of particularly massive stars, which gives rise to a highly
relativistic jet. Internal inhomogeneities in the expanding flow give rise to
internal shock waves that are believed to produce the gamma-rays we see. As the
jet travels further outward into the surrounding circumstellar medium
`external' shocks give rise to the afterglow emission seen in the X-ray,
optical and radio bands. Here we report on the early phases of the X-ray
emission of five GRBs. Their X-ray light curves are characterised by a rapid
fall-off for the first few hundred seconds, followed by a less rapid decline
lasting several hours. This steep decline, together with detailed spectral
properties of two particular bursts, shows that violent shock interactions take
place in the early jet outflows.


title:
VLT-SINFONI observations of Mrk 609 - A showcase for X-ray active
  galaxies chosen from a sample of AGN suitable for adaptive optics
  observations with natural guide stars

abstract:
  We will present first results of ESO-VLT AO-assisted integral-field
spectroscopy of a sample of X-ray bright AGN with redshifts of 0.04 < z < 1. We
constructed this sample by cross-correlating the SDSS and ROSAT surveys and
utilizing typical AO constraints. This sample allows for a detailed study of
the NIR properties of the nuclear and host environments with high spectral
resolution on the 100 pc scale. These objects can then be compared directly to
the local (z<0.01) galaxy populations (observed without AO) at the same linear
scale. As a current example, we will present observations of the z=0.034
Seyfert 1.8 galaxy Mrk 609 with the new AO-assisted integral-field spectrometer
SINFONI at the VLT. The successful observations show, that in the future -
while having observed more objects - we will be able to determine the presence,
frequency and importance of nuclear bars and/or circum-nuclear star forming
rings in these objects and address the question of how these X-ray luminous AGN
and their hosts are linked to optically/UV-bright QSOs, low-z QSOs/radio
galaxies, or ULIRGs.


title: Discovery of an extended ultraviolet disk in the nearby galaxy NGC4625

abstract:
  Recent far-UV (FUV) and near-UV (NUV) observations of the nearby galaxy
NGC4625 made by the Galaxy Evolution Explorer (GALEX) show the presence of an
extended UV disk reaching 4 times the optical radius of the galaxy. The
UV-to-optical colors suggest that the bulk of the stars in the disk of NGC4625
are currently being formed, providing a unique opportunity to study today the
physics of star formation under conditions similar to those when the normal
disks of spiral galaxies like the Milky Way first formed. In the case of
NGC4625, the star formation in the extended disk is likely to be triggered by
interaction with NGC4618 and possibly also with the newly discovered galaxy
NGC4625A. The positions of the FUV complexes in the extended disk coincide with
peaks in the H I distribution. The masses of these complexes are in the range
10^3-10^4 Msun with their Halpha emission (when present) being dominated by
ionization from single stars.


title: An Infrared Coronagraphic Survey for Substellar Companions

abstract:
  We have used the F160W filter (1.4-1.8 um) and the coronagraph on the
Near-InfraRed Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space
Telescope (HST) to survey 45 single stars with a median age of 0.15 Gyr, an
average distance of 30 pc, and an average H-magnitude of 7 mag. For the median
age we were capable of detecting a 30 M_Jup companion at separations between 15
and 200 AU. A 5 M_Jup object could have been detected at 30 AU around 36% of
our primaries. For several of our targets that were less than 30 Myr old, the
lower mass limit was as low as a Jupiter mass, well into the high mass planet
region. Results of the entire survey include the proper motion verification of
five low-mass stellar companions, two brown dwarfs (HR7329B and TWA5B) and one
possible brown dwarf binary (Gl 577B/C).


title:
A New Determination Of The Diffuse Galactic and Extragalactic Gamma-Ray
  Emission

abstract:
  The GALPROP model for cosmic-ray propagation is able to make explicit
predictions for the distribution of galactic diffuse gamma-rays. We compare
different propagation models with gamma-ray spectra measured by EGRET for
various regions of the sky. This allows sensitive tests of alternative
explanations for the apparent excess emission observed at GeV gamma-rays. We
find that a population of hard-spectrum gamma-ray sources cannot be solely
responsible for the excess since it also appears at high latitudes; on the
other hand a hard cosmic-ray electron spectrum cannot explain the gamma-ray
excess in the inner Galaxy. By normalizing the cosmic ray spectra within
reasonable bounds under preservation of their shape we are able to obtain our
best prediction of the Galactic component of diffuse gamma rays, and show that
away from the Galactic plane it gives an accurate prediction of the observed
gamma-ray intensities. On this basis we reevaluate the extragalactic gamma-ray
background. We find that for some energies previous work underestimated the
Galactic contribution and hence overestimated the background. The new EGRB
spectrum shows a positive curvature similar to that expected for models of the
extragalactic gamma-ray emission based on contributions from unresolved
blazars.


title:
Constraints on Intracluster Gas Bulk Motions in Clusters of Galaxies
  with ASCA

abstract:
  The recent detection of Doppler shifts of X-ray spectral lines in the
intracluster gas of the Centaurus and Perseus clusters of galaxies with ASCA
has raised the question of the frequency of such velocity gradients and their
relation to other cluster properties. To address this and improve the sample of
ICM velocity gradient candidates we carried out a systematic search of the ASCA
archive for clusters with suitable observing conditions that allow full
azimuthal mapping of gas velocities near the central regions. Here we present
the results of the azimuthal velocity distribution of a sample consisting of
the best" observed clusters for velocity analysis. Our sample encompasses
clusters with different physical and morphological characteristics, including
both well behaved "cooling flow" and dynamically active clusters. The gas
temperatures of the clusters in our sample range from 1.4 keV to 6.3 keV. We
find velocity substructures in ~ 15% of the clusters in our sample on the order
of a few x 1E3 km/s. The significance of the velocity gradients' is greater
than 99% in Abell 576 and RXJ0419.6+0225, the clusters where velocity gradients
are most significant. The velocity gradients are consistent with transitory
and/or rotational bulk motion. The velocity gradients in these clusters are
unlikely to be due to projected temperature anisotropies, ASCA PSF, intrachip
gain variations, and flux contamination from other sources. Chandra images of
these clusters do not show obvious cluster alignments within the field of view
covered by ASCA. We also noticed a high frequency (~50%) of anisotropic
temperature gradients in the core of "cooling flow" clusters, suggesting the
presence of frequent dynamical activity in the core of galaxy clusters.


title: On The Origin Of Unidentified EGRET Gamma-Ray Sources

abstract:
  The identification of celestial gamma-ray sources with astronomical objects
or object classes has remained the initial and most fundamental key for
understanding their physical nature. The observational characteristic of a
gamma-ray emitter and the conditions under which an astronomical object is able
to produce energetic gamma-ray emission defines the range of candidates
available for source identifications. The main obstacle must be seen in the
fact that a gamma-ray source location is often imprecise, a flux history could
only be established on the basis of weeks, and uncertainties in the gamma-ray
observables are considerably large. Therefore coordinated multifrequency
follow-up campaigns or spatial-statistical methods are required to assign
proper counterpart identifications. Although Active Galactic Nuclei and pulsars
are uniquely identified EGRET sources, many other gamma-ray sources still
remain unidentified. I will review properties of the population and highlight
the characteristics of potential counterparts of the still unidentified
gamma-ray sources detected by EGRET.


title: On the binary nature of 1RXS J162848.1-415241

abstract:
  We present spectroscopy of the optical counterpart to 1RXS J162848.1-41524,
also known as the microquasar candidate MCQC J162847-4152. All the data
indicate that this X-ray source is not a microquasar, and that it is a
single-lined chromospherically active binary system with a likely orbital
period of 4.9 days. Our analysis supports a K3IV spectral classification for
the star, which is dominant at optical wavelengths. The unseen binary component
is most likely a late-type (K7-M) dwarf or a white dwarf. Using the high
resolution spectra we have measured the K3 star's rotational broadening to be
vsini = 43 +/- 3 km/s and determined a lower limit to the binary mass ratio of
q(=M2/M1)>2.0. The high rotational broadening together with the strong CaII H &
K / Halpha emission and high-amplitude photometric variations indicate that the
evolved star is very chromospherically active and responsible for the
X-ray/radio emission.


title: Multiwavelength studies of WR 21a and its surroundings

abstract:
  We present results of high-resolution radio continuum observations towards
the binary star WR 21a (Wack 2134) obtained with the Australia Telescope
Compact Array (ATCA) at 4.8 and 8.64 GHz. We detected the system at 4.8 GHz (6
cm) with a flux density of 0.25+-0.06 mJy and set an upper limit of 0.3 mJy at
8.64 GHz (3 cm). The derived spectral index of alpha < 0.3
[S(nu)=k.nu**(alpha)] suggests the presence of non-thermal emission, probably
originating in a colliding-wind region. A second, unrelated radio source was
detected ~10" north of WR 21a at (RA, Dec)(J2000)=(10h 25m 56.49, -57deg 48'
34.4", with flux densities of 0.36 and 0.55 mJy at 4.8 and 8.64 GHz,
respectively, resulting in alpha = 0.72. HI observations in the area are
dominated by absorption against the prominent HII region RCW 49. Analysis of a
complete set of archived X-ray observations of WR 21a confirms its strong
variability but throws into doubt previous suggestions by Reig (1999) of a
period of years for the system. Finally, we comment on the association with the
nearby EGRET source 3EG J1027-5817.


title: Neutron Diffusion and Nucleosynthesis in an Inhomogeneous Big Bang Model

abstract:
  This article presents an original code for Big Bang Nucleosynthesis in a
baryon inhomogeneous model of the universe. In this code neutron diffusion
between high and low baryon density regions is calculated simultaneously with
the nuclear reactions and weak decays that compose the nucleosynthesis process.
The size of the model determines the time when neutron diffusion becomes
significant. This article describes in detail how the time of neutron diffusion
relative to the time of nucleosynthesis affects the final abundances of He4,
deuterium and Li7. These results will be compared with the most recent
observational constraints of He4, deuterium and Li7. This inhomogeneous model
has He4 and deuterium constraints in concordance for baryon to photon ratio eta
= (4.3 - 12.3) X 10^{-10} Li7 constraints are brought into concordance with the
other isotope constraints by including a depletion factor as high as 5.9. These
ranges for the baryon to photon ratio and for the depletion factor are larger
than the ranges from a Standard Big Bang Nucleosynthesis model.


title: New neighbours VI. Spectroscopy of DENIS nearby stars candidates

abstract:
  We present spectra of 36 nearby star candidates and 3 red giant candidates,
identified in the DENIS database by Phan-Bao et al. (2003). 32 of the dwarf
candidates are indeed nearby red dwarfs, with spectral types from M5.5 to M8.5.
Out of 11 targets with low proper motion (mu < 0.1$ arc-sec/yr) but a Reduced
Proper Motion above an inclusive threshold, 9 are red dwarfs. The 4
contaminants are all reddened F-K main sequence stars, and they could have been
eliminated by checking for some well known high latitude molecular clouds.
These stars might be of interest as probes of interstellar absorption. For the
red dwarfs we derive spectral types and spectroscopic distances, using a new
calibration of the PC3 spectral index to absolute magnitudes in the I, J, H and
K photometric bands.
  We confirm 2 new members of the 12 pc volume (2 new M8.5), and one M7.5 NLTT
object closer than 10pc. We also show that one quarter of the stars with
photometric distances under 30 pc have too small a proper motion for inclusion
in the NLTT catalog.


title:
Critical Examinations of QSO Redshift Periodicities and Associations
  with Galaxies in Sloan Digital Sky Survey Data

abstract:
  We have used the publicly available data from the Sloan Digital Sky Survey
and 2dF QSO Redshift Survey to test the hypothesis that QSOs are ejected from
active galaxies with periodic non-cosmological redshifts. For two different
intrinsic redshift models, namely the Karlsson $\log(1+z)$ model and Bell's
decreasing intrinsic redshift (DIR) model, we do two tests respectively. First,
using different criteria, we generate four sets of QSO-galaxy pairs and find
there is no evidence for a periodicity at the predicted frequency in
$\log(1+z)$, or at any other frequency. We then check the relationship between
high redshift QSOs and nearby active galaxies, and we find the distribution of
projected distance between high redshift QSOs and nearby active galaxies and
the distribution of redshifts of those active galaxies are consistent with a
distribution of simulated random pairs, completely different from Bell's
previous conclusion. We also analyze the periodicity in redshifts of QSOs, and
no periodicity is found in high completeness samples, contrary to the DIR
model. These results support that QSOs are not ejected from active galaxies.


title: Total and Jet Blandford-Znajek Power in Presence of Accretion Disk

abstract:
  A rotating black hole probably powers ultrarelativistic jets in gamma-ray
bursts, relativistic jets from some active galactic nuclei, and jets from some
black hole x-ray binaries. Prior estimates of the power output of a black hole
have assumed an infinitely thin disk, a magnetic field based upon a slowly
rotating black hole, and have not self-consistently determined the geometry or
magnitude of the magnetic field for a realistic accretion disk. We provide
useful formulae for the total and jet Blandford-Znajek (BZ) power and
efficiency as determined self-consistently from general relativistic
magnetohydrodynamic numerical models. Of all jet mechanisms, we suggest that
only the BZ mechanism is able to produce an ultrarelativistic jet.


title:
Jet Formation in Black Hole Accretion Systems I: Theoretical Unification
  Model

abstract:
  Two types of relativistic jets are suggested to form near accreting black
holes: a potentially ultrarelativistic Poynting-dominated jet and a
Poynting-baryon jet. One source of jet matter is electron-positron pair
production, which is driven by neutrino annihilation in GRBs and photon
annihilation in AGN and x-ray binaries. GRB Poynting-dominated jets are also
loaded by electron-proton pairs by the collisional cascade of Fick-diffused
free neutrons. We show that, for the collapsar model, the neutrino-driven
enthalpy flux (classic fireball model) is probably dominated by the
Blandford-Znajek energy flux, which predicts a jet Lorentz factor of
$\Gamma\sim 100-1000$. We show that radiatively inefficient AGN, such as M87,
are synchrotron-cooling limited to $\Gamma\sim 2-10$. Radiatively efficient
x-ray binaries, such as GRS1915+105, are Compton-drag limited to $\Gamma
\lesssim 2$, but the jet may be destroyed by Compton drag. However, the
Poynting-baryon jet is a collimated outflow with $\Gamma \sim 1-3$. The jet
from radiatively efficient systems, such as microquasar GRS1915+105, may
instead be a Poynting-baryon jet that is only relativistic when the disk is
geometrically thick. In a companion paper, general relativistic hydromagnetic
simulations of black hole accretion with pair creation are used to simulate jet
formation in GRBs, AGN, and x-ray binaries.


title: Jet Formation in Black Hole Accretion Systems II: Numerical Models

abstract:
  In a companion theory paper, we presented a unified model of jet formation.
We suggested that primarily two types of relativistic jets form near accreting
black holes: a potentially ultrarelativistic Poynting-dominated jet and a
Poynting-baryon jet. We showed that, for the collapsar model, the
neutrino-driven enthalpy flux (classic fireball model) is probably dominated by
the Blandford-Znajek energy flux, which predicts a jet Lorentz factor of
$\Gamma\sim 100-1000$. We showed that radiatively inefficient AGN, such as M87,
are synchrotron-cooling limited to $\Gamma\sim 2-10$. Radiatively efficient
x-ray binaries, such as GRS1915+105, are Compton-drag limited to $\Gamma
\lesssim 2$, but the jet may be destroyed by Compton drag. However, the
Poynting-baryon jet is a collimated outflow with $\Gamma \sim 1-3$. Here we
present general relativistic hydromagnetic simulations of black hole accretion
with pair creation used to simulate jet formation in GRBs, AGN, and x-ray
binaries. Our collapsar model shows the development of a patchy ``magnetic
fireball'' with typically $\Gamma\sim 100-1000$ and a Gaussian structure.
Temporal variability of the jet is dominated by toroidal field instabilities
for $\gtrsim 10^2$ gravitational radii. A broader Poynting-baryon jet with
$\Gamma\sim 1.5$ could contribute to a supernova.


title: Galaxy Rotation Curves Without Non-Baryonic Dark Matter

abstract:
  We apply the modified acceleration law obtained from Einstein gravity coupled
explaining galaxy rotation curves without exotic dark matter. Our sample of
galaxies includes low surface brightness (LSB) and high surface brightness
(HSB) galaxies, and an elliptical galaxy. In those cases where photometric data
are available, a best fit via the single parameter (M/L)_{stars} to the
luminosity of the gaseous (HI plus He) and luminous stellar disks is obtained.
Additionally, a best fit to the rotation curves of galaxies is obtained in
terms of a parametric mass distribution (independent of luminosity
observations) -- a two parameter fit to the total galactic mass, (or
mass-to-light ratio M/L), and a core radius associated with a model of the
galaxy cores using a nonlinear least-squares fitting routine including
estimated errors. The fits are compared to those obtained using Milgrom's
phenomenological MOND model and to the predictions of the Newtonian-Kepler
acceleration law.


title: Inflessence: a phenomenological model for inflationary quintessence

abstract:
  We present a phenomenologically motivated model which is able to give rise
both to an inflationary epoch and to the present day cosmic acceleration. We
introduce an approach where the energy density depends on the scale factor $a$
in such a way that a smooth transition from the inflation to the matter
dominated era and then to the nowadays accelerated expansion is achieved. We
use the dimensionless coordinate distance $y(z)$ to the Gold Type Ia Supernovae
dataset and to a sample comprising 20 radio galaxies, the shift parameter
${\cal{R}}$ and the acoustic peak parameter ${\cal{A}}$ to test whether the
model is in agreement with observations and to constrain its main parameters.
As an independent cross check, we also compare model predictions with the
lookback time to galaxy clusters and the age of the universe. Although
phenomenologically inspired, the model may be theoretically motivated either
resorting to a scenario with a scalar and phantom fields (eventually
interacting) or as an effective description arising from higher order gravity
theories.


title:
Local Supercluster Dynamics: External Tidal Impact of the PSCz sample
  traced by Optimized Numerical Least Action Method

abstract:
  We assess the extent to which the PSCz survey encapsulates the complete or
major share of matter inhomogeneities responsible for the external tidal forces
affecting the peculiar velocity flow within the Local Supercluster [LS]. We
investigate this issue on the basis of mock galaxy catalogs drawn from two
large Nbody simulations of cosmic structure formation in two different
cosmological scenarios. From these a variety of datasets is selected imitating
the observational conditions of either the volume-limited LS mimicking NBG
catalog or the deeper magnitude-limited PSCz catalog. The mildly nonlinear
dynamics in the mock NBG and PSCz velocities are analyzed by means of an
optimized implementation of the Least Action Principle, the Fast Action Method
[FAM]. By comparing the modeled and true velocities of the corresponding mock
catalogs we assess the extent and nature of the external tidal influence on the
LS volume. We find that the dynamics in the inner 30Mpc/h volume is strongly
affected by the external forces. Most of the external forces can be traced back
to a depth of no more than 100Mpc/h. This is concluded from the fact that the
FAM reconstructions of the 100Mpc/h PSCz volume appear to have included most
gravitational influences. In addition, we demonstrate that for all considered
cosmological models the bulk flow and shear components of the tidal velocity
field generated by the external distribution of PSCz galaxies provides
sufficient information for representing the full external tidal force field.


title:
Non-Gaussianity in Multi-field Stochastic Inflation with the Scaling
  Approximation

abstract:
  The statistics of multi-field inflation are investigated using the stochastic
approach. We analytically obtain the probability distribution function of
fields with the scaling approximation by extending the previous work by
Amendola. The non-Gaussian nature of the probability distribution function is
investigated decomposing the fields into the adiabatic and isocurvature
components. We find that the non-Gaussianity of the isocurvature component can
be large compared with that of the adiabatic component. The adiabatic and
isocurvature components may be correlated at nonlinear order in the skewness
and kurtosis even if uncorrelated at linear level.


title:
Could the 47 UMa Planetary System be a Second Solar System: predicting
  the Earth-like planets

abstract:
  (Abridged)We numerically investigated the dynamical architecture of 47 UMa
with the planetary configuration of the best-fit orbital solutions by Fischer
et al. We systematically studied the existence of Earth-like planets in the
region 0.05 AU $\leq a \leq 2.0$ AU for 47 UMa with numerical simulations, and
we also explored the packed planetary geometry and Trojan planets in the
system. In the simulations, we found that "hot Earths" at 0.05 AU $\leq a < $
0.4 AU can dynamically survive at least for 1 Myr. The Earth-like planets can
eventually remain in the system for 10 Myr in areas involved in the mean motion
resonances (MMR) (e.g., 3:2 MMR) with the inner companion. Moreover, we showed
that the 2:1 and 3:1 resonances are on the fringe of stability, while the 5:2
MMR is unstable. Additionally, the 2:1 MMR marks out a remarkable boundary
between chaotic and regular motions, inside, most of the orbits can survive,
outside, they are mostly lost in the orbital evolution. In a dynamical sense,
the most likely candidate for habitable environment is Earth-like planets with
orbits in the ranges 0.8 AU $\leq a < 1.0$ AU and 1.0 AU $ < a < 1.30$ AU
(except several unstable cases) with relatively low eccentricities. The Trojan
planets with low eccentricities and inclinations can secularly last at the
triangular equilibrium points of two massive planets. Hence, the 47 UMa
planetary system may be a close analog to our solar system.


title:
Reduced magnetic braking and the magnetic capture model for the
  formation of ultra-compact binaries

abstract:
  A binary in which a slightly evolved star starts mass transfer to a neutron
star can evolve towards ultra-short orbital periods under the influence of
magnetic braking. This is called magnetic capture. In a previous paper we
showed that ultra-short periods are only reached for an extremely small range
of initial binary parameters, in particular orbital period and donor mass. Our
conclusion was based on one specific choice for the law of magnetic braking,
and for the loss of mass and angular momentum during mass transfer. In this
paper we show that for less efficient magnetic braking it is impossible to
evolve to ultra-short periods, independent of the amount of mass and associated
angular momentum lost from the binary.


title: The Remnants of Intergalactic Supernovae

abstract:
  Intergalactic type-Ia supernovae (SNe-Ia) have been discovered recently in
rich galaxy clusters, likely the descendants of an intergalactic stellar
population found in recent years through a variety of tracers. We estimate the
observational signatures of the associated SN remnants (SNRs) in the unusual
intracluster medium (ICM) environment. If SNe-Ia still have a circumstellar
medium (CSM) at the time of explosion, then their remnants are visible in the
optical for ~100-1000 years, with properties similar to young galactic SNRs. In
contrast with galactic SNRs, in which the ejecta from the explosion interacts
with the ISM, intracluster SNRs become undetectable in the optical once their
ejecta passes beyond the CSM and enters the hot and tenuous ICM. If SNe-Ia have
a CSM, there should be ~150 young SNRs in the Virgo cluster, with
L(H-alpha)~10^{35} erg/s and angular size ~0.1''. We investigate the
possibility that members of this SNR population may have recently been
detected, but incorrectly identified as intergalactic HII regions.
Alternatively, if optical intergalactic SNRs do not exist in Virgo, this will
be evidence that SNe-Ia are devoid of a CSM, with implications for progenitor
scenarios. Regardless of the presence of a CSM, about 10 older radio SNRs per
square degree should be detectable in Virgo, with fluxes of ~0.1 mJy at 1 GHz.
Their angular sizes, morphologies, and lack of optical association with distant
galaxies can distinguish them from the much more numerous background
population. Their detection would provide a measurement of the intracluster SN
rate. Observations toward the site of SN1980I, a possibly intergalactic Virgo
SN-Ia, can test the existence of a CSM by comparison to our early-time
predictions for intergalactic SNR development.


title: AMICA, an astro-mapper for AMS

abstract:
  The Alpha Magnetic Spectrograph (AMS) is a composite particle detector to be
accommodated on the International Space Station (ISS) in 2008. AMS is mainly
devoted to galactic, charged Cosmic Rays studies, Antimatter and Dark Matter
searches. Besides the main, classical physics goals, capabilities in the field
of GeV and multi-GeV gamma astrophysics have been established and are under
investigation by a number of groups. Due to the unsteadiness of the ISS
platform, a star-mapper device is required in order to fully exploit the
intrinsic arc-min angular resolution provided by the Silicon Tracker. A
star-mapper is conceptually an imaging, optical instrument able to autonomously
recognize a stellar field and to calculate its own orientation with respect to
an inertial reference frame. AMICA (Astro Mapper for Instruments Check of
Attitude) on AMS is responsible for providing real-time information that is
going to be used off-line for compensating the large uncertainties in the ISS
flight attitude and the structural degrees of freedom. In this paper, we
describe in detail the AMICA sub-system and the accommodation/integration
issues and the in-flight alignment procedure adopting identified galactic
(pulsars) and extragalactic (AGNs) sources.


title:
Radiative transfer in moving media II. Solution of the radiative
  transfer equation in axial symmetry

abstract:
  A new method for the formal solution of the 2D radiative transfer equation in
axial symmetry in the presence of arbitrary velocity fields is presented. The
combination of long and short characteristics methods is used to solve the
radiative transfer equation. We include the velocity field in detail using the
Local Lorentz Transformation. This allows us to obtain a significantly better
description of the photospheric region, where the gradient of the global
velocity is too small for the Sobolev approximation to be valid. Sample test
calculations for the case of a stellar wind and a rotating atmosphere are
presented.


title: Polarization microvariability of BL Lac objects

abstract:
  We present the results of a systematic observational campaign designed to
search for microvariability in the optical polarization of BL Lac objects. We
have observed a sample formed by 8 X-ray-selected and 10 radio-selected
sources, looking for rapid changes in both the degree of linear polarization
and the corresponding polarization angle. The whole campaign was carried out
along the last three years, and most of the objects were observed at least on
two consecutive nights. The statistical properties of both classes of BL Lac
objects are compared, and some general conclusions on the nature of the
phenomenon are drawn. In general, radio selected sources seem to display higher
duty cycles for polarimetric microvariability and, on average, they have a
stronger polarization.


title: The XMM-Newton Slew Survey

abstract:
  XMM-Newton, with the huge collecting area of its mirrors and the high quantum
efficiency of its EPIC detectors, is the most sensitive X-ray observatory ever
flown. This is strikingly evident during slew exposures, which, while yielding
only at most 14 seconds of on-source exposure time, actually constitute a 2-10
keV survey ten times deeper than all other "all-sky" surveys. The current
(April 2005) XMM archive contains 374 slew exposures which give a uniform
coverage over around 10,000 square degrees (approx. 25% of the sky). Here we
describe the results of pilot studies, the current status of the XMM-Newton
Slew Survey, up-to-date results and our progress towards constructing a
catalogue of slew detections in the full 0.2-12 keV energy band.


title: Populations of AGB stars and LPVs in the Galaxy and Local Group

abstract:
  In this review I will discuss recent developments on the topic of resolved
Asymptotic Giant Branch (AGB) stars and Long Period Variables (LPVs) in our
Galaxy, the Magellanic Clouds, and the Local Group in general. Since the main
characteristics of AGB stars are (1) their infrared, (2) pulsational and (3)
chemical properties, it is fitting that I will focus on recent results from the
(a) 2MASS/DENIS and MSX near- and mid-IR surveys, the (b) micro-lensing surveys
and (c) dedicated narrow-band imaging surveys.


title: The disk vanishes

abstract:
  Recently published observations of VY Scl stars in their low,
long-intermediate and high states confirm our model (Hameury & Lasota 2002)
according to which accretion disks in such systems must vanish when their
temperature corresponds to thermally unstable configurations. An observational
confirmation of the hypothesis that the disk disappearance is caused by
magnetic effects would have important consequences for cataclysmic variable
evolution models.


title: The Excess Far-Infrared Emission of AGN in the Local Universe

abstract:
  We have cross-correlated the Sloan Digital Sky Survey (SDSS) second data
release spectroscopic galaxy sample with the IRAS faint-source catalogue (FSC).
Optical emission line ratios are used to classify the galaxies with reliable
IRAS 60 and 100 microns detections into AGN and normal star-forming galaxies.
We then create subsamples of normal galaxies and AGN that are very closely
matched in terms of key physical properties such as stellar mass, redshift,
size, concentration and mean stellar age (as measured by absorption line
indicators in the SDSS spectra). We then quantify whether there are systematic
differences between the IR luminosities of the galaxies and the AGN in the
matched subsamples. We find that the AGN exhibit a significant excess in far-IR
emission relative to the star-forming galaxies in our sample. The excesses at
60 and 100 microns are 0.21 +/- 0.03 dex and 0.12 +/- 0.035 dex in
log[L(60)/M*] and log[L(100)/M*], respectively. We then discuss whether the
far-IR excess is produced by radiation from the active nucleus that is absorbed
by dust or alternatively, by an extra population of young stars that is not
detectable at optical wavelengths.


title: A near-IR spectrum of the DO white dwarf RE J0503-285

abstract:
  We present a near-IR spectroscopic analysis of the intriguing DO white dwarf
RE J0503-285. The IR spectrum fails to reveal evidence of the presence of a
spatially unresolved, cool, late-type companion. Hence we have placed an
approximate limit on the spectral-type and mass of a putative companion (later
than M8, M<0.085Msun). This result rules out ongoing interaction between the
white dwarf and a close companion with M>0.085Msun as responsible for the
discrepancies between the observed photospheric abundances and model
predictions. As the possibility remains that there is a cooler companion lying
beyond the detection threshold of this study we use our modelling to estimate
the improvement in sensitivity offered by a Spitzer observation.


title: High-Energy Cosmic Rays and Neutrinos from Gamma-Ray Bursts

abstract:
  A complete model for the origin of high-energy >~10^{14} eV) cosmic rays from
gamma-ray bursts (GRBs) and implications of this hypothesis are described.
Detection of high-energy neutrinos from GRBs provide an unambiguous test of the
model. Evidence for cosmic-ray acceleration in GRBs is suggested by the
detection of anomalous gamma-ray components such as that observed from GRB
941017. Neutron beta-decay halos around star-forming galaxies such as the Milky
Way are formed as a consequence of this model. Cosmic rays from GRBs in the
Galaxy are unlikely to account for the ~10^{18} eV cosmic-ray excess reported
by the Sydney University Giant Air Shower Recorder (SUGAR), but could
contribute to past extinction events.


title: Nuclear fusion in dense matter: Reaction rate and carbon burning

abstract:
  In this paper we analyze the nuclear fusion rate between equal nuclei for all
five different nuclear burning regimes in dense matter (two thermonuclear
regimes, two pycnonuclear ones, and the intermediate regime). The rate is
determined by Coulomb barrier penetration in dense environments and by the
astrophysical S-factor at low energies. We evaluate previous studies of the
Coulomb barrier problem and propose a simple phenomenological formula for the
reaction rate which covers all cases. The parameters of this formula can be
varied, taking into account current theoretical uncertainties in the reaction
rate. The results are illustrated for the example of the ^{12}C+^{12}C fusion
reaction. This reaction is very important for the understanding of nuclear
burning in evolved stars, in exploding white dwarfs producing type Ia
supernovae, and in accreting neutron stars. The S-factor at stellar energies
depends on a reliable fit and extrapolation of the experimental data. We
calculate the energy dependence of the S-factor using a recently developed
parameter-free model for the nuclear interaction, taking into account the
effects of the Pauli nonlocality. For illustration, we analyze the efficiency
of carbon burning in a wide range of densities and temperatures of stellar
matter with the emphasis on carbon ignition at densities rho > 10^9 g/cc.


title: Bimodal Color Distribution in Hierarchical Galaxy Formation

abstract:
  We show how the observed bimodality in the color distribution of galaxies can
be explained in the framework of the hierarchical clustering picture in terms
of the interplay between the properties of the merging histories and the
feedback/star-formation processes in the progenitors of local galaxies. Using a
semi-analytic model of hierarchical galaxy formation, we compute the color
distributions of galaxies with different luminosities and compare them with the
observations. Our fiducial model matches the fundamental properties of the
observed distributions, namely: 1) the distribution of objects brighter than
M_r = -18 is clearly bimodal, with a fraction of red objects increasing with
luminosity; 2) for objects brighter than M_r = -21 the color distribution is
dominated by red objects with color u-r = 2.2-2.4; 3) the spread on the
distribution of the red population is smaller than that of the blue population;
4) the fraction of red galaxies is larger in denser environments, even for
low-luminosity objects; 5) the bimodality in the distribution persists up to z
= 1.5. We discuss the role of the different physical processes included in the
model in producing the above results.


title: Patterns of energy-dependent variability from Comptonization

abstract:
  We study fractional variability as a function of energy from black-hole X-ray
binaries on timescales from milliseconds to hundreds of seconds. We build a
theoretical model of energy-dependent variability in which the X-ray energy
spectrum varies in response to a changing physical parameter. We compare these
models to rms spectra obtained from RXTE PCA observations of black-hole
binaries XTE J1550-564 and XTE J1650-500. We show that two main variability
models are consistent with the data: variable seed photon input in the hard
state and variable power in the Comptonized component in the soft and very high
states. The lack of clear reflection features in the rms spectra implies that
the reflection and the X-ray continuum, when integrated over Fourier
frequencies, are correlated and vary with similar fractional amplitudes. Our
models predict two important features of rms spectra, not possible to be
clearly seen by the PCA due sensitivity limits. At soft X-rays, >~3 keV, we
predict the presence of a break in the rms spectrum at energy directly related
to the seed photon temperature. At higher energies, ~20--30 keV, we predict a
peak in the rms spectrum originating from the variability of the spectrum
produced by a hybrid thermal/non-thermal electron distribution. If these
features are confirmed by broad-band observations, they will impose important
constraints on the origin of the seed photons for Comptonization and the
electron distribution in the hot plasma.


title: Kaluza-Klein Dark Matter and Galactic Antiprotons

abstract:
  Extra dimensions offer new ways to address long-standing problems in beyond
the standard model particle physics. In some classes of extra-dimensional
models, the lightest Kaluza-Klein particle is a viable dark matter candidate.
In this work, we study indirect detection of Kaluza-Klein dark matter via its
annihilation into antiprotons. We use a sophisticated galactic cosmic ray
diffusion model whose parameters are fully constrained by an extensive set of
experimental data. We discuss how fluxes of cosmic antiprotons can be used to
exclude low Kaluza-Klein masses.


title:
Measuring the primordial power spectrum: Principal component analysis of
  the cosmic microwave background

abstract:
  We implement and investigate a method for measuring departures from
scale-invariance, both scale-dependent as well as scale-free, in the primordial
power spectrum of density perturbations using cosmic microwave background (CMB)
C_l data and a principal component analysis technique. The primordial power
spectrum is decomposed into a dominant scale-invariant Gaussian adiabatic
component plus a series of orthonormal modes whose detailed form only depends
the noise model for a particular CMB experiment. However, in general these
modes are localised across wavenumbers with 0.01 < k < 0.2 Mpc^-1, displaying
rapid oscillations on scales corresponding the acoustic peaks where the
sensitivity to primordial power spectrum is greatest. The performance of this
method is assessed using simulated data for the Planck satellite, and the full
cosmological plus power spectrum parameter space is integrated out using Markov
Chain Monte Carlo. As a proof of concept we apply this data compression
technique to the current CMB data from WMAP, ACBAR, CBI and VSA. We find no
evidence for the breaking of scale-invariance from measurements of four PCA
mode amplitudes, which is translated to a constraint on the scalar spectral
index n_S(k_0=0.04 Mpc^-1)=0.94+-0.04 in accordance with WMAP studies.


title: Fast outflow of neutral and ionized gas from the radio galaxy 3C 293

abstract:
  We detect a fast outflow of neutral and ionized gas with velocities up to
about 1000 km/s from the central region of radio galaxy 3C 293. With optical
spectroscopy we locate the bulk of the ionized gas outflow at the position of a
bright radio hot-spot in the inner radio jet, about 1 kpc east of the nucleus.
Given the presence of large amounts of cold gas and the distorted morphology of
the radio jet in this region, we argue that the ISM is pushed out by a severe
interaction with the radio plasma. The similarity of the outflow of HI with the
ionized gas outflow that we see at the position of the radio hot-spot suggests
that despite the high energies involved in the jet-ISM interaction, part of the
gas stays, or becomes again, neutral. In this paper we also present the
detection of HI emission in three nearby companions of 3C 293.


title: Cosmological constraints on a classical limit of quantum gravity

abstract:
  We investigate the cosmology of a recently proposed deformation of Einstein
gravity, emerging from quantum gravity heuristics. The theory is constructed to
have de Sitter space as a vacuum solution, and thus to be relevant to the
accelerating universe. However, this solution turns out to be unstable, and the
true phase space of cosmological solutions is significantly more complex,
displaying two late-time power-law attractors -- one accelerating and the other
dramatically decelerating. It is also shown that non-accelerating cosmologies
sit on a separatrix between the two basins of attraction of these attractors.
Hence it is impossible to pass from a decelerating cosmology to an accelerating
one, as required in standard cosmology for consistency with nucleosynthesis and
structure formation and compatibility with the data inferred from supernovae
Ia. We point out that alternative models of the early universe, such as the one
investigated here might provide possible ways to circumvent these requirements.


title:
The VIMOS VLT Deep Survey - Evolution of the luminosity functions by
  galaxy type up to z=1.5 from first epoch data

abstract:
  From the first epoch observations of the VVDS up to z=1.5 we have derived
luminosity functions (LF) of different spectral type galaxies. The VVDS data,
covering ~70% of the life of the Universe, allow for the first time to study
from the same sample and with good statistical accuracy the evolution of the
LFs by galaxy type in several rest frame bands from a purely magnitude selected
sample. The magnitude limit of the VVDS allows the determination of the faint
end slope of the LF with unprecedented accuracy. Galaxies have been classified
in four spectral classes, using their colours and redshift, and LFs have been
derived in the U, B, V, R and I rest frame bands from z=0.05 to z=1.5. We find
a significant steepening of the LF going from early to late types. The M*
parameter is significantly fainter for late type galaxies and this difference
increases in the redder bands. Within each of the galaxy spectral types we find
a brightening of M* with increasing redshift, ranging from =< 0.5 mag for early
type galaxies to ~1 mag for the latest type galaxies, while the slope of the LF
of each spectral type is consistent with being constant with redshift. The LF
of early type galaxies is consistent with passive evolution up to z~1.1, while
the number of bright early type galaxies has decreased by ~40% from z~0.3 to
z~1.1. We also find a strong evolution in the normalization of the LF of latest
type galaxies, with an increase of more than a factor 2 from z~0.3 to z~1.3:
the density of bright late type galaxies in the same redshift range increases
of a factor ~6.6. These results indicate a strong type-dependent evolution and
identifies the latest spectral types as responsible for most of the evolution
of the UV-optical luminosity function out to z=1.5.


title:
X-ray Cluster Associated with the z=1.063 CSS Quasar 3C 186: The Jet is
  NOT Frustrated

abstract:
  We report the Chandra discovery of an X-ray cluster at redshift z = 1.063
associated with the Compact Steep Spectrum radio loud quasar 3C 186
(Q0740+380). Diffuse X-ray emission is detected out to ~120 kpc from the quasar
and contains 741+/-40 net counts. The X-ray spectrum of the extended emission
shows strong Fe-line emission (EW=412eV) at the quasar redshift and confirms
the thermal nature of this diffuse component. We measure a cluster temperature
of 5.2(+1.2/-0.9) keV and an X-ray luminosity L(0.5-2 keV) ~ 6e44 erg/sec,
which are in agreement with the luminosity-temperature relation for
high-redshift clusters. This is the first detection of a bright X-ray cluster
around a luminous (L_bol ~1e47 erg/sec) CSS quasar at high redshift and only
the fifth z>1 X-ray cluster detected. We find that the CSS radio source is
highly overpressured with respect to the thermal cluster medium by about 3
orders of magnitude. This provides direct observational evidence that the radio
source is not thermally confined as posited in the ``frustrated'' scenario for
CSS sources. Instead, it appears that the radio source may be young and we are
observing it at an early stage of its evolution. In that case the radio source
could supply the energy into the cluster and potentially prevent its cooling.


title: Precision Determination of the Mass Function of Dark Matter Halos

abstract:
  The predicted mass function of dark matter halos is essential in connecting
observed galaxy cluster counts and models of galaxy clustering to the
properties of the primordial density field. We determine the mass function in
the concordance $\Lambda$CDM cosmology, as well as its uncertainty, using
sixteen $1024^3$-particle nested-volume dark-matter simulations, spanning a
mass range of over five orders of magnitude. Using the nested volumes and
single-halo tests, we find and correct for a systematic error in the
friends-of-friends halo-finding algorithm. We find a fitting form and full
error covariance for the mass function that successfully describes the
simulations' mass function and is well-behaved outside the simulations'
resolutions. Estimated forecasts of uncertainty in cosmological parameters from
future cluster count surveys have negligible contribution from remaining
statistical uncertainties in the central cosmology multiplicity function. There
exists a potentially non-negligible cosmological dependence (non-universality)
of the halo multiplicity function.


title:
Tracking Dark Energy with the ISW effect: short and long-term
  predictions

abstract:
  We present an analysis of the constraining power of future measurements of
the Integrated Sachs-Wolfe (ISW) effect on models of the equation of state of
dark energy as a function of redshift, w(z). To achieve this, we employ a new
parameterization of w, which utilizes the mean value of w(z) (<w>) as an
explicit parameter. This helps to separate the information contained in the
estimation of the distance to the last scattering surface (from the CMB) from
the information contained in the ISW effect. We then use Fisher analysis to
forecast the expected uncertainties in the measured parameters from future ISW
observations for two models of dark energy with very different time evolution
properties. For example, we demonstrate that the cross-correlation of Planck
CMB data and LSST galaxy catalogs will provide competitive constraints on w(z),
compared to a SNAP-like SNe project, for models of dark energy with a rapidly
changing equation of state (e.g. 'Kink' models). Our work confirms that, while
SNe measurements are more suitable for constraining variations in w(z) at low
redshift, the ISW effect can provide important independent constraints on w(z)
at high z.


title: Period recovery success rate expected with Gaia

abstract:
  The Gaia satellite was selected as a cornerstone mission of the European
Space Agency (ESA) in October 2000 and confirmed in 2002 with a current target
launch date of 2011. The Gaia mission will gather on the same observational
principles as Hipparcos detailed astrometric, photometric and spectroscopic
properties of about 1 billion sources brighter than mag V=20. The nature of the
measured objects ranges from NEOs to gamma ray burst afterglows and encompasses
virtually any kind of stars in our Galaxy. Gaia will provide multi-colour (in
about 20 passbands extending over the visible range) photometry with typically
250 observations distributed over 40 well separated epochs during the 5-year
mission. The multi-epoch nature of the project will permit to detect and
analyse variable sources whose number is currently estimated in the range of
several tens of million, among the detectable sources.
  In this paper, we assess the performances of Gaia in analysing photometric
periodic phenomena. We first present quickly the overall observational
principle before discussing the implication of the scanning law in the time
sampling. Then from extensive simulations one assesses the performances in the
recovery of periodic signals as a function of the period, signal-to-noise ratio
and position on the sky for simple sinusoidal variability.


title:
A Unified, Merger-Driven Model for the Origin of Starbursts, Quasars,
  the Cosmic X-Ray Background, Supermassive Black Holes and Galaxy Spheroids

abstract:
  We present an evolutionary model for starbursts, quasars, and spheroidal
galaxies in which mergers between gas-rich galaxies drive nuclear inflows of
gas, producing intense starbursts and feeding the buried growth of supermassive
black holes (BHs) until feedback expels gas and renders a briefly visible
optical quasar. The quasar lifetime and obscuring column density depend on both
the instantaneous and peak luminosity of the quasar, and we determine this
dependence using a large set of simulations of galaxy mergers varying host
galaxy properties, orbital geometry, and gas physics. We use these fits to
deconvolve observed quasar luminosity functions (LFs) and obtain the evolution
of the formation rate of quasars with a certain peak luminosity, n(L_peak,z).
Quasars spend extended periods of time at luminosities well below peak, and so
n(L_peak) has a maximum corresponding to the 'break' in the observed LF,
falling off at both brighter and fainter luminosities. From n(L_peak) and our
simulation results, we obtain self-consistent fits to hard and soft X-ray and
optical quasar LFs and predict many observables, including: column density
distributions of optical and X-ray samples, the LF of broad-line quasars in
X-ray samples and the broad-line fraction as a function of luminosity, active
BH mass functions, the distribution of Eddington ratios at z~0-2, the z=0 mass
function of relic BHs and total mass density of BHs, and the cosmic X-ray
background. In every case, our predictions agree well with observed estimates,
and unlike previous modeling attempts, we are able to reproduce them without
invoking any ad hoc assumptions about source properties or distributions. We
provide a library of Monte Carlo realizations of our models for comparison with
observations. (Abridged)


title: Hot Neutron and Quark Star Evolution

abstract:
  The physics of compact objects is one of the very actively developing
branches of theoretical investigations, since the careful analysis of different
models for the internal structure of these objects, their evolutionary
characteristics and the comparison with modern observational data give access
to discriminate among various speculations about the state of matter under
extreme conditions.
  The lecture provides an overview to the problem of neutron star cooling
evolution. We discuss the scheme and necessary inputs for neutron star cooling
simulations from the background of a microscopic modeling in order to present
the surface temperature - age characteristics of hybrid neutron stars including
the determination of main regulators of the cooling process, the question of
neutrino production and diffusion.


title: Further spectroscopic observations of the CSL-1 object

abstract:
  CSL-1 is a peculiar object (R.A._{2000}= 12h 23m 30.5"; Dec_{2000}= -12deg
38' 57.0") which, for its photometric and spectroscopic properties, is possibly
the first case of gravitational lensing by a cosmic string. In this paper we
present additional evidences, based on medium-high resolution VLT + FORS1
observations, that the spectra of the two components of CSL-1 are identical
within a confidence level higher than 99.9% and the velocity difference of the
two components is consistent with zero. This result adds further confidence to
the interpretation of the system as a true lens.


title: New Mass Loss Measurements from Astrospheric Lyman-alpha Absorption

abstract:
  Measurements of stellar mass loss rates are used to assess how wind strength
varies with coronal activity and age for solar-like stars. Mass loss generally
increases with activity, but we find evidence that winds suddenly weaken at a
certain activity threshold. Very active stars are often observed to have polar
starspots, and we speculate that the magnetic field geometry associated with
these spots may be inhibiting the winds. Our inferred mass-loss/age relation
represents an empirical estimate of the history of the solar wind. This result
is important for planetary studies as well as solar/stellar astronomy, since
solar wind erosion may have played an important role in the evolution of
planetary atmospheres.


title:
Millimetre continuum observations of southern massive star formation
  regions. I. SIMBA observations of cold cores

abstract:
  We report the results of a SEST 1.2 mm continuum emission survey toward
regions previously identified as harbouring a methanol maser and/or an UC HII
region, typically indicative of massive star formation. Emission is detected
toward all of the methanol maser and UC HII regions targeted, implying that
these objescts are associated with cold, deeply embedded objects.
  We have also identified a large number (253) of sources within the SIMBA
maps, which are devoid of maser and radio continuum emission. These `mm-only'
cores may be an entirely new class of source that represents an earlier stage
in the evolution of massive stars, prior to the onset of methanol maser
emission. Or, they may harbour protoclusters, which do not contain any high
mass stars (i.e. below the HII). Alternatively, they may represent a
cross-section of both, where the more massive mm-only cores are a precursor to
the methanol maser and the least massive mm-only cores will form intermediate
mass stars.
  Analysis of the mm-only sources shows that they are less massive ({\= M} =
0.9 x 10^{3} Msun), and smaller ({\= R} = 0.4 pc) than sources with methanol
maser and/or radio continuum emission, which collectively have a mean mass of
2.5 x 10^{3} Msun and a mean radius of 0.7 pc.