title: Dark matter within high surface brightness spiral galaxies

abstract:
  We present results from a detailed dynamical analysis of five high surface
brightness, late type spirals, studied with the aim to quantify the
luminous-to-dark matter ratio inside their optical radii. The galaxies' stellar
light distribution and gas kinematics have been observed and compared to
hydrodynamic gas simulations, which predict the 2D gas dynamics arising in
response to empirical gravitational potentials, which are combinations of
differing stellar disk and dark halo contributions. The gravitational potential
of the stellar disk was derived from near-infrared photometry, color-corrected
to constant (M/L); the dark halo was modelled by an isothermal sphere with a
core. Hydrodynamic gas simulations were performed for each galaxy for a
sequence of five different mass fractions of the stellar disk and for a wide
range of spiral pattern speeds. These two parameters mainly determine the
modelled gas distribution and kinematics. The agreement between the
non-axisymmetric part of the simulated and observed gas kinematics permitted us
to conclude that the galaxies with the highest rotation velocities tend to
possess near-maximal stellar disks. In less massive galaxies, with v_max<200
km/s, the mass of the dark halo at least equals the stellar mass within 2-3
R_disk. The simulated gas morphology provides a powerful tool to determine the
dominant spiral pattern speed. The corotation radius for all galaxies was found
to be constant at R_corotation ~ 3 R_disk and encloses the strong part of the
stellar spiral in all cases.


title: Collimation of a Central Wind by a Disk-Associated Magnetic Field

abstract:
  We present the results of time-dependent, numerical magnetohydrodynamic
simulations of a realistic young stellar object outflow model with the addition
of a disk-associated magnetic field. The outflow produced by the magnetic
star-disk interaction consists of an episodic jet plus a wide-angle wind with
an outflow speed comparable to that of the jet (100--200 km/s). An initially
vertical field of << 0.1 Gauss, embedded in the disk, has little effect on the
wind launching mechanism, but we show that it collimates the entire flow (jet +
wide wind) at large (several AU) distances. The collimation does not depend on
the polarity of the vertical field. We also discuss the possible origin of the
disk-associated field.


title: Dense gas-star systems: Super-massive stars evolution

abstract:
  In the 60s and 70s super-massive central objects (from now onwards SMOs) were
thought to be the main source of active galactic nuclei (AGNs) characteristics
(luminosities of $L \approx 10^{12} L_{\odot}$). The release of gravitational
binding energy by the accretion of material on to an SMO in the range of $10^7
- 10^9 M_{\odot}$ has been suggested to be the primary powerhouse (Lynden-Bell
1969).
  That rather exotic idea in early time has become common sense nowadays. Not
only our own galaxy harbours a few million-solar mass black hole (Genzel 2001)
but also many of other non-active galaxies show kinematic and gas-dynamic
evidence of these objects (Magorrian et al. 1998) The concept of central
super-massive stars (SMSs henceforth) (${\cal M} \ge 5 \times 10^4 M_{\odot}$,
where ${\cal M}$ is the mass of the SMS) embedded in dense stellar systems was
suggested as a possible explanation for high- energy emissions phenomena
occurring in AGNs and quasars (Vilkoviski 1976, Hara 1978), such as X-ray
emissions (Bahcall and Ostriker, 1975). SMSs and super-massive black holes
(SMBHs) are two possibilities to explain the nature of SMOs, and SMSs may be an
intermediate step towards the formation of SMBHs (Rees 1984). In this paper we
give the equations that describe the dynamics of such a dense star-gas system
which are the basis for the code that will be used in a prochain future to
simulate this scenario. We also briefly draw the mathematical fundamentals of
the code


title: Clusters of galaxies with modified Newtonian dynamics (MOND)

abstract:
  X-ray emitting clusters of galaxies are considered in the context of modified
Newtonian dynamics (MOND). I show that self-gravitating isothermal gas spheres
are not good representations of rich clusters with respect to the radial gas
density distribution as indicated by the X-ray surface brightness. Pure gas
spheres with a density distribution described by a ``beta'' model, as observed,
also fail because, with MOND, these objects are far from isothermal. These
problems may be resolved by adding an additional dark mass component in the
central regions; a constant density sphere contained within two core radii and
having a total mass of one to two times that in the gas. With this additional
component, the observed luminosity-temperature relation for clusters of
galaxies is reproduced. When the observed X-ray surface brightness distribution
in actual clusters is modeled by such a two-component structure, the typical
mass discrepancy is three to four times smaller than with Newtonian dynamics.
Thus while MOND significantly reduces the mass of the dark component in
clusters it does not remove it completely. I speculate on the nature of the
dark component and argue that this is not a fundamental problem for MOND.


title:
On the Invariant Distribution of Galaxies in the re--mie plane out to z
  = 0.64

abstract:
  We study the evolution of the relation between half-light (effective) radius,
r_e, and mean surface brightness, mi_e, known as Kormendy relation, out to
redshift z=0.64 in V-band restframe on the basis of a large sample of
spheroidal galaxies (N=228) belonging to three clusters of galaxies. The
present sample constitutes the largest data set for which the Kormendy relation
is investigated up to a look-back time of 6 Gyr (H_0= 70 Km/s/Mpc, Omega_M=0.3,
Omega_Lambda=0.7). A new fitting procedure, which suitably accounts for
selection criteria effects, allows for the first time to study the trend of the
slope (beta) and of the intrinsic dispersion (sigma_mi_e) of the Kormendy
relation, and the properties of the whole distribution in the r_e -- mi_e,
plane as a function of look-back time. The slope beta of the relation does not
change from z=0.64 to the present epoch: beta=2.92+/-0.08, implying a tight
constraint of 18--28% on the variation of the stellar formation epoch along the
sequence of spheroidal galaxies per decade of radius. The intrinsic dispersion
of the relation, sigma_i_<mi>_e=0.40+/-0.03, does not vary with redshift and
the distribution of galaxy sizes as well as the distribution in the plane of
the effective parameters do not vary among the clusters, as proven by the
Kolmogorov--Smirnov tests. We conclude that, whatever the mechanism driving
galaxy evolution is, it does not affect significantly the properties of bright
galaxies in the log(r_e) -- mi_e, plane at least since z=0.64. The evolution of
the zeropoint of the Kormendy relation is fully explained by the cosmological
dimming in an expanding universe plus the passive luminosity evolution of
stellar populations with high formation redshift (z_f>2).


title: Thermodynamics and Self-Gravitating Systems

abstract:
  This work assembles some basic theoretical elements on thermal equilibrium,
stability conditions, and fluctuation theory in self-gravitating systems
illustrated with a few examples. Thermodynamics deals with states that have
settled down after sufficient time has gone by. Time dependent phenomena are
beyond the scope of this paper. While thermodynamics is firmly rooted in
statistical physics, equilibrium configurations, stability criteria and the
destabilizing effect of fluctuations are all expressed in terms of
thermodynamic functions. The work is not a review paper but a pedagogical
introduction which may interest theoreticians in astronomy and astrophysicists.
It contains sufficient mathematical details for the reader to redo all
calculations. References are only to seminal works or readable reviews. (Except
in the ultimate sub-section.) Delicate mathematical problems are mentioned but
are not discussed in detail.


title:
3D convection simulations of the outer layers of the Sun using realistic
  physics

abstract:
  This paper describes a series of 3D simulations of shallow inefficient
convection in the outer layers of the Sun. The computational domain is a closed
box containing the convection-radiation transition layer, located at the top of
the solar convection zone. The most salient features of the simulations are
that: i)The position of the lower boundary can have a major effect on the
characteristics of solar surface convection (thermal structure, kinetic energy
and turbulent pressure). ii)The width of the box has only a minor effect on the
thermal structure, but a more significant effect on the dynamics (rms
velocities). iii)Between the surface and a depth of 1 Mm, even though the
density and pressure increase by an order of magnitude, the vertical
correlation length of vertical velocity is always close to 600 km. iv) In this
region the vertical velocity cannot be scaled by the pressure or the density
scale height. This casts doubt on the applicability of the mixing length
theory, not only in the superadiabatic layer, but also in the adjacent
underlying layers. v) The final statistically steady state is not strictly
dependent on the initial atmospheric stratification.


title:
Theory and astrophysical consequences of a magnetized torus around a
  rapidly rotating black hole

abstract:
  (Abbrev.) We analyze the topology, lifetime, and emissions of a torus around
a black hole formed in hypernovae and black hole-neutron star coalescence. The
torus is ab initio uniformly magnetized, represented by two counter oriented
current-rings, and develops a state of suspended accretion against a "magnetic
wall" around the black hole. Magnetic stability of the torus gives rise to a
new fundamental limit EB/Ek<0.1 for the ratio of poloidal magnetic field
energy-to-kinetic energy. The lifetime of rapid spin of the black hole is
effectively defined by the timescale of dissipation of black hole-spin energy
in the horizon, and satisfies T= 40s (MH/7MSun)(R/6MH)^4(0.03MH/MT) for a black
hole of mass MH surrounded by a torus of mass MT and radius R. The torus
converts a major fraction Egw/Erot=0.1 into gravitational radiation through a
finite number of multipole mass-moments, and a smaller fraction into MeV
neutrinos and baryon-rich winds. At a source distance of 100Mpc, these
emissions over N=2e4 periods give rise to a characteristic strain amplitude
\sqrt{N}hchar=6e-21. We argue that torus winds create an open magnetic
flux-tube on the black hole, which carries a minor and standard fraction
Ej/Erot=1e-3 in baryon-poor outflows to infinity. We identify this baryon poor
output of tens of seconds with GRBs with contemporaneous and strongly
correlated emissions in gravitational radiation, conceivably at multiple
frequencies. Ultimately, this leaves a black hole binary surrounded by a
supernova remnant.


title:
A comparative study of the X-ray afterglow properties of optically
  bright and dark GRBs

abstract:
  We have examined the complete set of X-ray afterglow observations of dark and
optically bright GRBs performed by BeppoSAX until February 2001. X-ray
afterglows are detected in 90% of the cases. We do not find significant
differences in the X-ray spectral shape, in particular no higher X-ray
absorption in GRBs without optical transient (dark GRBs) compared to GRBs with
optical transient (OTGRBs). Rather, we find that the 1.6-10 keV flux of OTGRBs
is on average about 5 times larger than that of the dark GRBs. A K-S test shows
that this difference is significant at 99.8% probability. Under the assumption
that dark and OTGRB have similar spectra, this could suggest that the first are
uncaught in the optical band because they are just faint sources. In order to
test this hypothesis, we have determined the optical-to-X ray flux ratios of
the sample. OTGRBs show a remarkably narrow distribution of flux ratios, which
corresponds to an average optical-to-x spectral index 0.794\pm 0.054. We find
that, while 75% of dark GRBs have flux ratio upper limits still consistent with
those of OT GRBs, the remaining 25% are 4 - 10 times weaker in optical than in
X-rays. The significance of this result is equal to or higher than 2.6 sigma.
If this sub-population of dark GRBs were constituted by objects assimilable to
OTGRBs, they should have shown optical fluxes higher than upper limits actually
found. We discuss the possible causes of their behaviour, including a possible
occurrence in high density clouds or origin at very high redshift and a
connection with ancient, Population III stars.


title:
uvbyCaHbeta CCD Photometry of Clusters. III. The Most Metal-Rich Open
  Cluster, NGC 6253

abstract:
  CCD photometry on the intermediate-band uvbyCaH-beta system is presented for
the old open cluster, NGC 6253. Despite a high level of field star
contamination due to its location toward the galactic center, combination of
the data from the multiple color indices with the core cluster sample derived
from radial star counts leads to the identification of a set of highly
probable, single cluster members. Photometric analysis of a select sample of 71
turnoff stars produces a reddening value of E(b-y) = 0.190 +/-0.002 (s.e.m.) or
E(B-V) = 0.260 +/- 0.003 (s.e.m.) from 71 stars. The metallicity indices,
delta-m1 and delta-hk, both identify this cluster as the most metal-rich object
studied on either system to date. Simple extrapolation of the available
metallicity calibrations leads to [Fe/H] ranging from +0.7 to +0.9. Metal-rich
isochrones with overshoot imply an age between 2.5 and 3.5 Gyr, with an
apparent distance modulus between (m-M)= 11.6 and 12.2, depending upon the
isochrones used. The improvement in the fit using alpha-enhanced isochrones may
indicate that the cluster [Fe/H] is closer to +0.4, but the photometric indices
are distorted by an elemental distribution other than a scaled solar. The
galacto- centric position of the cluster, in conjunction with data for other
clusters and Cepheids, is consistent with the inner disk reaching and
maintaining a metallicity well above solar since the early history of the disk,
unlike the solar neighborhood.


title:
A Generalized Potential with Adjustable Slope: A Hydrostatic Alternative
  to Cluster Cooling Flows

abstract:
  I discuss a new gravitational potential, Phi(r) ~ (r_0^n+r^n)^(-1/n), for
modeling the mass distribution of spherical systems. This potential has a
finite mass and generates a density profile with adjustable inner slope 2-n. A
gas embedded in this potential has hydrostatic temperature and gas density
distributions that are elementary functions of n, greatly simplifying the task
of measuring the slope from X-ray data. I show that this model is successful in
describing the rising temperature profile and steep gas density profile often
seen in cooling flow clusters. An application to the Abell 478 cluster of
galaxies yields an inner slope 2-n = 1.0 +/- 0.2 (90%), consistent with the
inner regions of collisionless dark matter halos first simulated by Navarro,
Frenk, and White. The potential is also useful for cluster dynamics: it is a
generalization of the familiar Hernquist and Plummer potentials, and because it
is invertible, it allows for easy analytic calculation of particle phase space
distribution functions in terms of n.


title:
Cosmic Shear with Next Generation Redshift Surveys as a Cosmological
  Probe

abstract:
  The expansion of the universe causes spacetime curvature, distinguishing
between distances measured along and transverse to the line of sight. The ratio
of these distances, e.g. the cosmic shear distortion of a sphere defined by
observations of large scale structure as suggested by Alcock & Paczynski,
provides a method for exploring the expansion as a function of redshift. The
theoretical sensitivity to cosmological parameters, including the dark energy
equation of state, is presented. Remarkably, sensitivity to the time variation
of the dark energy equation of state is best achieved by observations at
redshifts z<1. While systematic errors greatly degrade the theoretical
sensitivity, this probe may still offer useful parameter estimation, especially
in complementarity with a distance measure like the Type Ia supernova method
implemented by SNAP. Possible future observations of the Alcock-Paczynski
distortion by the KAOS project on a 8 meter ground based telescope are
considered.


title:
Causality and Sound Speed for General Scalar Field Models, including w <
  -1, tachyonic, phantom, k-essence and curvature corrections

abstract:
  The result from the SN1a projects suggest that the dark energy can be
represented by a fluid with w<-1. However, it is commonly argued that a fluid
with |w|>1 contradicts causality.
  Here, we will show that a fluid with |w|>1 does not contradict causality if
$w$ is not constant. Scalar field are the most promising candidates for
describing the dark energy and they do not have a constant equation of state
parameter w. Scalar potentials may lead to regions where w is larger or smaller
than one and even regions where the group velocity $d p/d\rho$ diverges.
  We study the evolution of scalar field perturbations and we show that the
"sound speed" is always smaller than the speed of light independently of the
value of w=p/\rho or d p/d\rho. In general, it is neither the phase velocity
nor the group velocity that gives the "sound speed". In the analysis we include
the special cases of $|w|>1$, tachyonic, phantom, k-essence scalar fields and
curvature corrections. Our results show that scalar fields do not contradict
causality as long as there is dispersion.


title:
Deuterium Toward Two Milky Way Disk Stars: Probing Extended Sight Lines
  with the Far Ultraviolet Spectroscopic Explorer

abstract:
  We have carried out an investigation of the abundance of deuterium along two
extended sight lines through the interstellar medium (ISM) of the Galactic
disk. The data include Far Ultraviolet Spectroscopic Explorer (FUSE)
observations of HD 195965 (B1Ib) and HD 191877 (B0V), as well as Space
Telescope Imaging Spectrograph (STIS) observations of HD 195965. The distances
to HD 195965 and HD 191877, derived from spectroscopic parallax, are 794+/-200
pc and 2200+/-550 pc, respectively, making these the longest Galactic disk
sight lines in which deuterium has been investigated with FUSE. The higher
Lyman lines clearly show the presence of deuterium. We use a combination of
curve of growth analyses and line profile fitting to determine the DI abundance
toward each object. We also present column densities for OI and NI toward both
stars, and HI measured from Ly-alpha absorption in the STIS spectrum of HD
195965. The D/H ratios along these sight lines are lower than the average value
found with FUSE for the local interstellar medium (37 to 179 pc from the Sun).
These observations lend support to earlier detections of variation in D/H over
distances greater than a few hundred pc. The D/H and O/H values measured along
these sight lines support the expectation that the ISM is not well mixed on
distances of ~1000 pc.


title: Probing Broad Absorption Line Quasar Outflows: X-ray Insights

abstract:
  Energetic outflows appear to occur in conjunction with active mass accretion
onto supermassive black holes. These outflows are most readily observed in the
approximately 10% of quasars with broad absorption lines, where the observer's
line of sight passes through the wind. Until fairly recently, the paucity of
X-ray data from these objects was notable, but now sensitive hard-band missions
such as Chandra and XMM-Newton are routinely detecting broad absorption line
quasars. The X-ray regime offers qualitatively new information for the
understanding of these objects, and these new results must be taken into
account in theoretical modeling of quasar winds.


title: The Cosmic Microwave Background

abstract:
  I review the discovery of the temperature fluctuations in the cosmic
microwave background radiation. The underlying theory and the implications for
cosmology are reviewed, and I describe the prospects for future progress.


title: Motions of Isolated G-Band Bright Points in the Solar Photosphere

abstract:
  Magnetic elements on the quiet sun are buffeted by convective flows that
cause lateral motions on timescales of minutes. The magnetic elements can be
observed as bright points (BPs) in the G band at 4305 {\AA}. We present
observations of BPs based on a long sequence of G-band images recorded with the
Dutch Open Telescope (DOT) and post-processed using speckle masking techniques.
  From these images we measured the proper motions of isolated BPs and derived
the auto-correlation function of their velocity relative to the solar
granulation pattern. The accuracy of BP position measurements is estimated to
be less than 23 km on the Sun. The rms velocity of BPs (corrected for
measurement errors) is about 0.89 km s$^{-1}$, and the correlation time of BP
motions is about 60 s. This rms velocity is about 3 times the velocity measured
using cork tracking, almost certainly due to the fact that isolated BPs move
more rapidly than clusters of BPs. We also searched for evidence of vorticity
in the motions of G band BPs.


title: Resolved Mid-IR Emission in the Narrow Line Region of NGC 4151

abstract:
  We present subarcsecond resolution mid infrared images of NGC 4151 at 10.8
micron and 18.2 micron. These images were taken with the University of Florida
mid-IR camera/spectrometer OSCIR at the Gemini North 8-m telescope. We resolve
emission at both 10.8 micron and 18.2 micron extending ~ 3.5" across at a P.A.
of ~ 60 degrees. This coincides with the the narrow line region of NGC 4151 as
observed in [OIII] by the Hubble Space Telescope. The most likely explanation
for this extended mid-IR emission is dust in the narrow line region heated by a
central engine. We find no extended emission associated with the proposed torus
and place an upper limit on its mid-IR size of less than or equal to ~ 35 pc.


title: A BeppoSAX Observation of the IC1262 Galaxy Cluster

abstract:
  We present an analysis of BeppoSAX observations of the IC1262 galaxy cluster
and report the first temperature and abundance measurements, along with
preliminary indications of diffuse, nonthermal emission. By fitting a 6' (~360
h_50^-1 kpc) region with a single Mewe-Kaastra-Liedahl model with photoelectric
absorption, we find a temperature of 2.1 - 2.3 keV, and abundance of 0.45 -
0.77 (both 90% confidence). We find the addition of a power-law component
provides a statistically significant improvement (F-test = 90%) to the fit. The
addition of a second thermal component also improves the fit but we argue that
it is physically implausible. The power-law component has a photon index
(Gamma_X) of 0.4 - 2.8 and a nonthermal flux of (4.1 - 56.7) x 10-5 photons
cm^-2 s^-1 over the 1.5 - 10.5 keV range in the Medium Energy Concentrator
spectrometer detector. An unidentified X-ray source found in the ROSAT High
Resolution Imager observation (~0'.9 from the center of the cluster) is a
possible explanation for the nonthermal flux; however, additional evidence of
diffuse, nonthermal emission comes from the NRAO VLA Sky Survey and the
Westerbork Northern Sky Survey radio measurements, in which excess diffuse,
radio flux is observed after point-source subtraction. The radio excess can be
fitted to a simple power law with a spectral index of ~1.8, which is consistent
with the nonthermal X-ray emission spectral index. The steep spectrum is
typical of diffuse emission and the size of the radio source implies that it is
larger than the cD galaxy and not due to a discreet source.


title: Entropy Injection as a Global Feedback Mechanism

abstract:
  Both preheating of the intergalactic medium and radiative cooling of low
entropy gas have been proposed to explain the deviation from self-similarity in
the cluster L_x-T_x relation and the observed entropy floor in these systems.
However, severe overcooling of gas in groups is necessary for radiative cooling
alone to explain the observations. Non-gravitational entropy injection must
therefore still be important in these systems. We point out that on scales of
groups and below, gas heated to the required entropy floor cannot cool in a
Hubble time, regardless of its subsequent adiabatic compression. Preheating
therefore shuts off the gas supply to galaxies, and should be an important
global feedback mechanism for galaxy formation. Constraints on global gas
cooling can be placed from the joint evolution of the comoving star formation
rate and neutral gas density. Preheating at high redshift can be ruled out;
however the data does not rule out passive gas consumption without inflow since
z~2. Since for preheated gas t_cool > t_dyn, we speculate that preheating could
play a role in determining the Hubble sequence: at a given mass scale, high
sigma peaks in the density field collapse early to form ellipticals, while low
sigma peaks collapse late and quiescently accrete preheated gas to form
spirals. The entropy produced by large scale shock-heating of the intergalatic
medium is significant only at late times, z<1, and cannot produce these
effects.


title: Gravitational Lensing by a Compound Population of Halos: Standard Models

abstract:
  Based on observed rotation curves of galaxies and theoretical simulations of
dark matter halos, there are reasons for believing that at least three
different types of dark matter halos exist in the Universe classified by their
masses M and the inner slope of mass density -\alpha: Population A (galaxies):
10^{10} h^{-1} M_\odot < M < 2 \times 10^{13} h^{-1} M_\odot, \alpha = 2;
Population B (cluster halos): M > 2 \times 10^{13} h^{-1} M_\odot, \alpha =
1.3; and Population C (dwarf halos): M < 10^{10} h^{-1} M_\odot, \alpha = 1.3.
In this paper we calculate the lensing probability produced by such a compound
population of dark halos, for both image separation and time delay, assuming
that the mass function of halos is given by the Press-Schechter function and
the Universe is described by an LCDM, OCDM, or SCDM model. The LCDM model is
normalized to the WMAP observations, OCDM and SCDM models are normalized to the
abundance of rich clusters. We compare the predictions of the different
cosmological models with observational data and show that, both LCDM and OCDM
models are marginally consistent with the current available data, but the SCDM
model is ruled out. The fit of the compound model to the observed correlation
between splitting angle and time delay is excellent but the fit to the number
vs splitting angle relation is only adequate using the small number of sources
in the objective JVAS/CLASS survey. A larger survey of the same type would have
great power in discriminating among cosmological models. Furthermore,
population C in an LCDM model has a unique signature in the time domain, an
additional peak at ~3 seconds potentially observable in GRBs, which makes it
distinguishable from variants of CDM scenarios, such as warm dark matter,
repulsive dark matter, or collisional dark matter.


title:
The bias of galaxies and the density of the universe from the 2dF galaxy
  redshift survey

abstract:
  By studying the bispectrum of the galaxy distribution in the 2dF galaxy
redhsift survey (2dFGRS), we have shown that 2dFGRS galaxies are unbiased
tracers of the mass distribution. This allows us the break the degeneracy
intrinsic to power spectrum studies, between the matter density parameter
Omega_m and the bias parameter b, and to obtain an accurate measurement of
Omega_m: Omega_{m,z_{eff}}=0.27 \pm 0.06, a measurement obtained from the
2dFGRS alone, independently from other data sets. This result has to be
interpreted as Omega_m at the effective redshift of the survey z_{eff}=0.17.
Extrapolated at z=0 we obtain Omega_m=0.2 \pm 0.06 for the LCDM model. This
constraint on the matter density parameter when combined with cosmic microwave
background constraints on the flatness of the Universe, show firm evidence that
the Universe is dominated by a vacuum energy component.


title: Clusters and Superclusters in the Sloan Digital Sky Survey

abstract:
  Two-dimensional high-resolution density field of galaxies of the Early Data
Release of the Sloan Digital Sky Survey with a smoothing lengths 0.8 h^{-1} Mpc
is applied to extract clusters of galaxies, and a low-resolution field with
smoothing lengths 10^{-1} Mpc to extract superclusters of galaxies. We compare
properties of density field clusters and superclusters with Abell clusters, and
superclusters found on the basis of Abell clusters. We found that clusters in
high-density environment have a luminosity a factor of about 5 higher than in
low-density environment. There exists a large anisotropy between the SDSS
Northern and Southern sample in the properties of clusters and superclusters:
most luminous clusters and superclusters in the Northern sample are a factor of
2 more luminous than the respective systems in the Southern sample.


title: X ray emission line profile modeling of hot stars

abstract:
  The launch of high-spectral-resolution x-ray telescopes (Chandra, XMM) has
provided a host of new spectral line diagnostics for the astrophysics
community. In this paper we discuss Doppler-broadened emission line profiles
from highly supersonic outflows of massive stars. These outflows, or winds, are
driven by radiation pressure and carry a tremendous amount of kinetic energy,
which can be converted to x rays by shock-heating even a small fraction of the
wind plasma. The unshocked, cold wind is a source of continuum opacity to the x
rays generated in the shock-heated portion of the wind. Thus the emergent line
profiles are affected by transport through a two-component, moving, optically
thick medium. While complicated, the interactions among these physical effects
can provide quantitative information about the spatial distribution and
velocity of the x-ray-emitting and absorbing plasma in stellar winds. We
present quantitative models of both a spherically-symmetric wind and a wind
with hot plasma confined in an equatorial disk by a dipole magnetic field.


title: Explosion Mechanisms of Massive Stars

abstract:
  One of the central problems in supernova theory is the question how massive
stars explode. Understanding the physical processes that drive the explosion is
crucial for linking the stellar progenitors to the final remnants and for
predicting observable properties like explosion energies, neutron star and
black hole masses, nucleosynthetic yields, explosion anisotropies, and pulsar
kicks. Here we review different suggestions for the explosion mechanism and
discuss the constraints that can or cannot be deduced from observations. The
most refined and detailed hydrodynamical models are available for
neutrino-driven supernova explosions, although the viability of this mechanism
has yet to be demonstrated convincingly. Since spherical models do not explode,
the hope rests on the helpful effects of convection inside the nascent neutron
star and in the neutrino-heated region behind the stalled shock. We present the
first two-dimensional simulations of these processes which have been performed
with a Boltzmann solver for the neutrino transport and a state-of-the-art
description of neutrino-matter interactions. Our most complete models fail, but
convection brings them encouragingly close to a success. An explosion could be
obtained by just a minor modification of the neutrino transport, in which case
the exploding model fulfills important requirements from observations
(abridged).


title: EUV excess in the inner Virgo cluster

abstract:
  Observations with the Extreme UltraViolet Explorer (EUVE) satellite have
shown that the inner region of the Virgo cluster (centered in M87 galaxy) has a
strong Extreme UltraViolet (EUV) emission (up to $13^{\prime}$) in excess to
the low-energy tail expected from the hot, diffuse IntraCluster Medium (ICM).
Detailed observations of large scale radio emission and upper limits for hard,
non-thermal X-ray emission in the $2 - 10$ keV energy band have been also
reported. Here we show that all available observations can be accounted for by
the existence of two electron Populations (indicated as I and II) in the M87
Galaxy. The mildly relativistic Population I is responsible for the EUV excess
emission via IC scattering of CBR and starlight photons. Population II
electrons (with higher energy) are instead responsible for the radio emission
through synchrotron mechanism. The same electrons also give rise to hard
non-thermal X-ray emission (via IC scattering of CBR photons), but the
resulting power is always below the upper bounds placed by present
observations. The non-negligible energy budget of the two electron populations
with respect to that associated with thermal electrons indicates that the M87
galaxy is not today in a quiescent (relaxed) phase. Nuclear activity and
merging processes could have made available this energy budget that today is
released in the form of relativistic electrons.


title: Core Collapse and Then? The Route to Massive Star Explosions

abstract:
  The rapidly growing base of observational data for supernova explosions of
massive stars demands theoretical explanations. Central of these is a
self-consistent model for the physical mechanism that provides the energy to
start and drive the disruption of the star. We give arguments why the delayed
neutrino-heating mechanism should still be regarded as the standard paradigm to
explain most explosions of massive stars and show how large-scale and even
global asymmetries can result as a natural consequence of convective overturn
in the neutrino-heating region behind the supernova shock. Since the explosion
is a threshold phenomenon and depends sensitively on the efficiency of the
energy transfer by neutrinos, even relatively minor differences in numerical
simulations can matter on the secular timescale of the delayed mechanism. To
enhance this point, we present some results of recent one- and two-dimensional
computations, which we have performed with a Boltzmann solver for the neutrino
transport and a state-of-the-art description of neutrino-matter interactions.
Although our most complete models fail to explode, the simulations demonstrate
that one is encouragingly close to the critical threshold because a modest
variation of the neutrino transport in combination with postshock convection
leads to a weak neutrino-driven explosion with properties that fulfill
important requirements from observations.


title:
The Mechanism of Core-Collapse Supernovae and the Ejection of Heavy
  Elements

abstract:
  We present here the first results of two-dimensional hydrodynamical
simulations of the neutrino-heating phase in the collapsed core of a 15 solar
mass star, where the neutrino transport is treated with a variable Eddington
factor method for solving the Boltzmann transport equation, and the neutrino
interactions include nucleon-nucleon bremsstrahlung, nucleon recoils and
correlations, and weak-magnetism effects as well as direct interactions between
neutrinos of different flavors. With the given input physics (neutrino
reactions and nuclear equation of state), our best simulations do not develop
strong convection in the neutrino-heating layer behind the shock and do not
yield explosions. With about 30% higher neutrino-energy deposition behind the
shock, however, an explosion occurs on a timescale of 150 ms after core bounce.
It leaves behind a neutron star with an initial baryonic mass of 1.4 solar
masses and ejects the N = 50 isotopes of Sr, Y and Zr in amounts consistent
with Galactic abundances.


title:
New insights into the photometric structure of Blue Compact Dwarf
  Galaxies from a deep Near-Infrared study

abstract:
  We present deep Near-Infrared (NIR) imaging of Blue Compact Dwarf Galaxies
(BCDs), allowing for the first time to derive and systematize the NIR
structural properties of their stellar low-surface brightness (LSB) host
galaxies. Compared to optical data, NIR images, being less contamined by the
extended stellar and ionized gas emission from the starburst, permit to study
the LSB host galaxy closer to its center. We find that radial surface
brightness profiles (SBPs) of the LSB hosts show at large radii a mostly
exponential intensity distribution, in agreement with previous optical studies.
At small to intermediate radii, however, the NIR data reveal an inwards
flattening with respect to the outer exponential slope ("type V SBPs", Binggeli
& Cameron 1991) in the LSB component of more than one half of the sample BCDs.
This result may constitute an important observational constraint to the
dynamics and evolution of BCDs. We apply a modified exponential fitting
function (Papaderos et al. 1996a) to parametrize and systematically study type
V profiles in BCDs. A Sersic law is found to be less suitable for studying the
LSB component of BCDs, since it yields very uncertain solutions.


title:
Deep XMM-Newton observation of a northern LMC field: I. Selected X-ray
  sources

abstract:
  First results from a deep XMM-Newton observation of a field in the Large
Magellanic Cloud (LMC) near the northern rim of the supergiant shell LMC 4 are
presented. Spectral and temporal analyses of a sample of selected X-ray sources
yielded two new candidates for supernova remnants, a supersoft X-ray source and
a likely high mass X-ray binary (HMXB) pulsar. From the fourteen brightest
sources up to ten are active galactic nuclei in the background of the galaxy
which can be used as probes for the interstellar medium in the LMC. From the
three previously known HMXBs the Be/X-ray binary EXO 053109-6609.2 was the
brightest source in the field, allowing a more detailed analysis of its X-ray
spectrum and pulse profile. During the pulse EXO 053109-6609.2 shows eclipses
of the X-ray emitting areas with increased photo-electric absorption before and
after the eclipse. The detection of X-ray pulsations with a period of 69.2 s is
confirmed for RX J0529.8-6556 and a possible period of 272 s is discovered from
XMMU J053011.2-655122. The results are discussed with respect to individual
sources as well as in the view of source population studies in the vicinity of
the supergiant shell LMC 4.


title: Scale Interactions and Galaxy Evolution

abstract:
  To understand galaxies and their evolution, it is necessary to describe how
the different scales interact: how the microscopic physics, such as star
formation, or the large scale physics, such as galaxy interactions may modify
the galaxy global shapes. The purpose of this review is to point out some
general or recent topics related to such scale interactions, both observational
and theoretical, which are relevant in the present understanding of galaxies.


title:
The impact of the early stages of radio source evolution on the ISM of
  the host galaxies

abstract:
  The study of both neutral and ionized gas in young radio sources is providing
key information on the effect the radio plasma has on the ISM of these objects.
We present results obtained for the compact radio sources PKS1549-79, 4C12.50
and PKS1814-63 and for the intermediate-size radio galaxy 3C459. At least in
the first two, low ionisation optical emission lines and HI absorption appear
to be associated with the extended, but relatively quiescent, dusty cocoon
surrounding the nucleus. The [OIII] lines are, on the other hand, mostly
associated with the region of interaction between the radio plasma and the ISM,
indicating a fast outflow from the canter. A case of fast outflow (up to ~1000
km/s) is also observed in HI in the radio source 4C12.50. As the radio source
evolves, any obscuring material along the radio axis is swept aside until,
eventually, cavities (of the same kind as observed e.g. in Cygnus A) are
hollowed out on either side of the nucleus. We may witness this phase in the
evolution of a radio source in the radio galaxy 3C459.


title: The nature of the "Composite" Seyfert/Star-forming Galaxies

abstract:
  We present the results obtained with BeppoSAX observations of the three
Composite Seyfert/star-forming galaxies: IRAS 20051-1117, IRAS 04392-0123 and
IRAS 01072+4954. These sources belong to an enigmatic class of X-ray sources
detected in the ROSAT All-Sky Survey (Moran et al. 1996) which is composed of 6
low redshift galaxies. Their optical spectra are dominated by the features of
HII galaxies while their X-ray luminosities (< 10^{42} ergs/s) are typical of
Seyfert galaxies. IRAS 20051-1117 shows a 2-10 keV spectrum well described by a
power-law with photon index = 1.9 and low intrinsic absorption. This result,
the ratio Flux(2-10 keV)/Flux([OIII]) and the significant X-ray variability
detected, clearly rule out a Compton thick nature of this source. IRAS
04392-0123 and IRAS 01072+4954, instead, have a BeppoSAX flux a factor of ~
50-80 smaller than in the previous ROSAT observations, resulting in poor
statistics, that prevents detailed modeling.


title: B2 0648+27: a radio galaxy in a major merger

abstract:
  We present WSRT observations of the neutral hydrogen in the nearby radio
galaxy B2 0648+27. In emission, we detect a very large amount of HI (M_HI = 1.1
x 10^10 M_sun) that is distributed in a very extended disk, or ring-like
structure, of about 160 kpc in size. We also detect HI absorption against the
central radio continuum component. The detection of the HI, its structure and
kinematics, give us key information for building a possible evolutionary
scenario. The characteristics of the detected HI are explained as the result of
a major merger event that is likely to have occurred <10^9 yr ago.
Interestinly, we find that, when observed in radio continuum at higher
resolution, this galaxy has a double lobed, steep spectrum structure of about 1
kpc in size. Thus, despite its low radio power, B2 0648+27 bears striking
similarities with Compact Symmetric Objects, i.e. objects believed to represent
the early phase of radio galaxies (< few thousand yrs old). B2~0648+27 is one
of the few nearby radio galaxies where extended neutral hydrogen has been
detected so far. This, and other recent results, appear however to indicate
that nearby radio galaxies are more often gas rich than commonly assumed. The
phenomena described are likely to be much more common at high redshift and
galaxies like B2 0648+27 may provide valuable information on the evolution of
high redshift radio sources.


title: Interstellar triply deuterated ammonia

abstract:
  Research on interstellar ND3 is reviewed and updated from the discovery
papers. Results from observations of a dozen sources at centimeter and
submillimeter wavelengths are presented. The two data sets are consistent, but
do not constrain the excitation conditions in the ND3-emitting gas. The column
density ratios of NH3:NH2D, NH2D:ND2H and ND2H:ND3, observed in similar sized
beams, are ~10, and present a challenge for both the gas-phase and the
grain-surface chemistry scenarios of deuterium fractionation. The role of
shocks and of CO depletion in deuterium chemistry is discussed.


title: Sulphur chemistry in the envelopes of massive young stars

abstract:
  We present submillimeter observations of SO, SO2, H2S, H2CS, OCS,
  NS and HCS+ toward nine massive young stars. The outflow contributes ~50% to
the SO and SO2 emission in 15-20'' beams, more than for CS, where it is 10%.
The SO2 abundance increases from dark cloud levels in the outer envelope (T<100
K) to levels seen in hot cores and shocks in the inner envelope (T>100 K).
Molecular abundances are consistent with a model of ice evaporation in an
envelope with gradients in temperature and density for a chemical age of ~30000
yr. The high observed abundance of OCS, the fact that T_ex (OCS) >> T_ex (H2S),
and the data on solid OCS and H2S all suggest that the major sulphur carrier in
grain mantles is OCS rather than H2S. For most other sulphur-bearing molecules,
the source-to-source abundance variations by factors of up to 10 do not
correlate with previously established evolutionary trends in temperature
tracers. These species probe the chemically inactive outer envelope. Our data
set does not constrain the abundances of H2S and SO in the inner envelope,
which, together with SO2, are required to use sulphur as a clock.


title: Jets from subpc to kpc scale

abstract:
  The Chandra discovery of bright X-ray emission from kpc-scale jets provides
us unprecedented insights into the physical state of the plasma in the flow. In
particular it is possible to get good constraints on the power and pressure in
bright knots. For a group of selected sources with blazar-type cores it is also
possible to constrain the physical quantities of the jet at sub-pc scale. We
discuss how these results can help us to connect the properties of the jet at
different scales.


title:
Luminosity function and density field of the Sloan and Las Campanas
  Redshift Survey

abstract:
  The luminosity function of galaxies of the Early Data Release of the Sloan
Digital Sky Survey (SDSS) and the Las Campanas Redshift Survey (LCRS) is
calculated. The luminosity function depends on redshift, density of the
environment and is different for the Norther and Southern slice of SDSS.
Luminosity functions is used to derive the number and luminosity density fields
of galaxies of the SDSS and LCRS surveys with a grid size of 1 h^{-1} Mpc for
flat cosmological models with \Omega_m=0.3 and \Omega_\Lambda =0.7. We find
that the luminosity function depends on the density of the environment: in
high-density regions brightest galaxies are more luminous than in low-density
regions by a factor up to 5.


title: Particle acceleration in ultra-relativistic parallel shock waves

abstract:
  Monte-Carlo computations for highly relativistic parallel shock particle
acceleration are presented for upstream flow gamma factors,
$\Gamma=(1-V_{1}^{2}/c^{2})^{-0.5}$ with values between 5 and $10^{3}$. The
results show that the spectral shape at the shock depends on whether or not the
particle scattering is small angle with $\delta \theta < \Gamma^{-1}$ or large
angle, which is possible if $\lambda > 2r_{g} \Gamma^{2}$ where $\lambda$ is
the scattering mean free path along the field line and $r_{g}$ the gyroradius,
these quantities being measured in the plasma flow frame. The large angle
scattering case exhibits distinctive structure superimposed on the basic
power-law spectrum, largely absent in the pitch angle case. Also, both cases
yield an acceleration rate faster than estimated by the conventional,
non-relativistic expression, $t_{acc}=[c/(V_{1}-V_{2})]
[\lambda_{1}/V_{1}+\lambda_{2}/V_{2}]$ where '1' and '2' refer to upstream and
downstream and $\lambda$ is the mean free path. A $\Gamma^{2}$ energy
enhancement factor in the first shock crossing cycle and a significant energy
multiplication in the subsequent shock cycles are also observed. The results
may be important for our understanding of the production of very high energy
cosmic rays and the high energy neutrino and gamma-ray output from Gamma Ray
Bursts (GRB) and Active Galactic Nuclei (AGN).


title: Particle acceleration in ultra-relativistic oblique shock waves

abstract:
  We perform Monte Carlo simulations of diffusive shock acceleration at highly
relativistic oblique shock waves. High upstream flow Lorentz gamma factors are
used, which are relevant to models of ultra relativistic particle shock
acceleration in Active Galactic Nuclei (AGN) central engines and relativistic
jets and Gamma Ray Burst (GRB) fireballs. We investigate numerically the
acceleration properties -in the ultra relativistic flow regime of $\Gamma \sim
10-10^{3}$- such as angular distribution, acceleration time constant, particle
energy gain versus number of crossings and spectral shapes. We perform
calculations for sub-luminal and super-luminal shocks, using two different
approaches respectively. The $\Gamma^{2}$ energization for the first crossing
cycle and the significantly large energy gain for subsequent crossings as well
as the high 'speed up' factors found, are important in supporting the Vietri
and Waxman models on GRB ultra-high energy cosmic ray, neutrino, and gamma-ray
output.


title: New Detections of Optical Emission from Kiloparsec-scale Quasar Jets

abstract:
  We report initial results from the detection of optical emission in the
arcsecond-scale radio jets of two quasars utilizing images from the {\it Hubble
Space Telescope} archive. The optical emission has a very knotty appearance and
is consistent with synchrotron emission from highly relativistic electrons in
the jet. Combining these observations with those of previously reported
features in other quasars, an emerging trend appears to be that their
radio-to-optical spectral indices are steeper than those of similar features in
jets of lower power radio sources.


title: Does the Sun Shine by pp or CNO Fusion Reactions?

abstract:
  We show that solar neutrino experiments set an upper limit of 7.8% (7.3%
including the recent KamLAND measurements) to the fraction of energy that the
Sun produces via the CNO fusion cycle, which is an order of magnitude
improvement upon the previous limit. New experiments are required to detect CNO
neutrinos corresponding to the 1.5% of the solar luminosity that the standard
solar model predicts is generated by the CNO cycle.


title: Chandra Analysis of Abell 496 - No Chemical Gradients Across Cold Fronts

abstract:
  We present the results of a spatially-resolved spectroscopic analysis of the
galaxy cluster Abell 496 with the S3 chip on-board the Chandra satellite. We
confirm the presence of a central positive temperature gradient consistent with
a cooling flow, but with a minimum gas temperature of ~0.5-0.9 keV. The cluster
also exhibits sharp edges in gas density and temperature which are consistent
with "cold front" substructures. The iron abundance profile is not radially
symmetric relative to the cluster center. Towards the direction of the most
prominent (northerly) cold front, the iron abundance is roughly flat, with
nearly solar values. In the opposite (southerly) direction from the center, the
iron abundance distribution shows an "off-center" peak. Various abundance
ratios suggest that the heavy elements in the central regions of the cluster
are dominated by SN Ia ejecta. However, for radii greater than 100 kpc, the
abundance ratios vary in such a way that different abundance ratios provide
very different estimates of the proportion of SN Ia/II ejecta. Nonetheless,
observed abundances and abundance ratios are continuous across the cold fronts,
which suggests that the cold fronts are not likely to be the result of a
subcluster merger. We suggest instead that the cold fronts in A496 are caused
by "sloshing" of the central cooling flow gas, induced by the motion of the cD
about the cluster center.


title:
A Thickness of Stellar Disks of Edge-on Galaxies and Position of Their
  Truncation Radii

abstract:
  The relationship between the geometrical properties of stellar disks (a
flatness and truncation radius) and the disk kinematics are considered for
edge-on galaxies. It is shown that the observed thickness of the disks and the
approximate constancy of their thickness along the radius well agrees with the
condition of their marginal local gravitational stability. As a consequence,
those galaxies whose disks are thinner should harbor more massive dark haloes.
The correlation between the de-projeced central brightness of the disks and
their flatness is found (the low surface brightness disks tend to be the
thinniest ones). We also show that positions of observed photometrically
determined truncation radii $R_{cut}$ for the stellar disks support the idea of
marginal local gravitational stability of gaseous protodisks at $R =R_{cut}$,
and hence the steepening of photometric profiles may be a result of too
inefficient star formation beyond $R_{cut}$.


title:
A multi-colour study of the dark GRB 000210 host galaxy and its
  environment

abstract:
  We present UBVRIZJsHKs broad band photometry of the host galaxy of the dark
gamma-ray burst (GRB) of February 10, 2000. These observations represent the
most exhaustive photometry given to date of any GRB host galaxy. A grid of
spectral templates have been fitted to the Spectral Energy Distribution (SED)
of the host. The derived photometric redshift is z=0.842^+0.054_-0.042, which
is in excellent agreement with the spectroscopic redshift (z=0.8463+/-0.0002)
proposed by Piro et al. (2002) based on a single emission line. Furthermore, we
have determined the photometric redshift of all the galaxies in an area of
6'x6' around the host galaxy, in order to check for their overdensity in the
environment of the host. We find that the GRB 000210 host galaxy is a
subluminous galaxy (L ~ 0.5+/-0.2 L*), with no companions above our detection
threshold of 0.18+/-0.06 L*. Based on the restframe ultraviolet flux a star
formation rate of 2.1+/-0.2 Solar Masses per year is estimated. The best fit to
the SED is obtained for a starburst template with an age of 0.181^+0.037_-0.026
Gyr and a very low extinction (Av~0). We discuss the implications of the
inferred low value of Av and the age of the dominant stellar population for the
non detection of the GRB 000210 optical afterglow.


title:
The Correlation Between Supermassive Black Hole Mass and the Structure
  of Ellipticals and Bulges

abstract:
  We demonstrate a strong correlation between supermassive black hole (SMBH)
mass and the global structure of ellipticals and bulges: more centrally
concentrated bulges and ellipticals (higher Sersic index $n$) host higher-mass
black holes. This correlation is as good as that previously found between SMBH
mass and central velocity dispersion, with comparable scatter. In addition, by
carefully modeling the bulges of disk galaxies so that bars, inner disks, and
the like do not accidentally contribute to bulge light, we find that the
correlation between SMBH mass and bulge or elliptical luminosity is similarly
close.


title:
Captain Cook, the Terrestrial Planet Finder and the Search for
  Extraterrestrial Intelligence

abstract:
  Over two hundred years ago Capt. James Cook sailed up Whitsunday Passage,
just a few miles where we now sit, on a voyage of astronomical observation and
discovery that remains an inspiration to us all. Since the prospects of our
visiting planets beyond our solar system are slim, we will have to content
ourselves with searching for life using remote sensing, not sailing ships.
Fortunately, a recently completed NASA study has concluded that a Terrestrial
Planet Finder could be launched within a decade to detect terrestrial planets
around nearby stars. A visible light coronagraph using an 8-10 m telescope, or
an infrared nulling interferometer, operated on either a $\sim40$ m structure
or separated spacecraft, could survey over 150 stars, looking for habitable
planets and signs of primitive life. Such a mission, complemented by projects
(Kepler and Eddington) that will provide statistical information on the
frequency of Earth-sized planets in the habitable zone, will determine key
terms in the ``Drake equation'' that describes the number of intelligent
civilizations in the Universe.


title: The Search for Terrestrial Planets: What Do we Need to Know?

abstract:
  The goal of finding and characterizing habitable planets in other solar
systems represents one of humanity's greatest scientific challenges. NASA and
ESA have initiated studies of missions that could accomplish this goal within
the next ten years. What precursor knowledge do we need before we can initiate
such a mission? How large should the first steps be in a program whose ultimate
aim is to detect life on other planets? This talk describes different concepts
for NASA's Terrestrial Planet Finder and discusses potential precursors in a
program that balances scientific return, technological advance, and
programmatic risk.


title: Investigating Galaxy Clusters through Gamma-ray Emission

abstract:
  We address the role of gamma-ray astronomy in the investigation of nonthermal
processes in the large scale structure of the universe. Based on EGRET upper
limits on nearby galaxy clusters (GCs) we constrain the acceleration efficiency
of CR electrons at intergalactic shocks to <=1 % than the shock ram pressure.
That implies a contribution to the cosmic gamma-ray background from
intergalactic shocks of order 25 % of the measured level. We model spatial and
spectral properties of nonthermal gamma-ray emission due to shock accelerated
cosmic-rays (CRs) in GCs and emphasize the importance of imaging capability of
upcoming gamma-ray facilities for a correct interpretation of the observational
results. GC observations at this photon energy will help us understand the
origin of the radio emitting particles, the possible level of CR pressure and
the strength of magnetic fields in intracluster environment and possibly will
allow us detect the accretion shocks.


title: Halo Substructure and the Power Spectrum

abstract:
  In this proceeding, we present the results of a semi-analytic study of CDM
substructure as a function of the primordial power spectrum. We apply our
method to several tilted models in the LCDM framework with n=0.85-1.1,
sigma_8=0.65-1.2 when COBE normalized. We also study a more extreme, warm dark
matter-like spectrum that is sharply truncated below a scale of 10^10 h^-1
Msun. We show that the mass fraction of halo substructure is not a strong
function of spectral slope, so it likely will be difficult to constrain tilt
using flux ratios of gravitationally lensed quasars. On the positive side, all
of our CDM-type models yield projected mass fractions in good agreement with
strong lensing estimates: f \sim 1.5% at M \sim 10^8 Msun. The truncated model
produces a significantly smaller fraction, f \lsim 0.3%, suggesting that warm
dark matter-like spectra may be distinguished from CDM spectra using lensing.
We also discuss the issue of dwarf satellite abundances, with emphasis on the
cosmological dependence of the map between the observed central velocity
dispersion of Milky Way satellites and the maximum circular velocities of their
host halos. In agreement with earlier work, we find that standard LCDM
over-predicts the estimated count of Milky Way satellites at fixed Vmax by an
order of magnitude, but tilted models do better because subhalos are less
concentrated. Interestingly, under the assumption that dwarfs have isotropic
velocity dispersion tensors, models with significantly tilted spectra (n \lsim
0.85, sigma_8 \lsim 0.7) may under-predict the number of large Milky Way
satellites with Vmax \gsim 40 km/s.


title:
Color superconducting quark matter core in the third family of compact
  stars

abstract:
  We investigate first order phase transitions from $\beta$-equilibrated
hadronic matter to color flavor locked quark matter in compact star interior.
The hadronic phase including hyperons and Bose-Einstein condensate of $K^-$
mesons is described by the relativistic field theoretical model with density
dependent meson-baryon couplings. The early appearance of hyperons and/or
Bose-Einstein condensate of $K^-$ mesons delays the onset of phase transition
to higher density. In the presence of hyperons and/or $K^-$ condensate, the
overall equations of state become softer resulting in smaller maximum masses
than the cases without hyperons and $K^-$ condensate. We find that the maximum
mass neutron stars may contain a mixed phase core of hyperons, $K^-$ condensate
and color superconducting quark matter. Depending on the parameter space, we
also observe that there is a stable branch of superdense stars called the third
family branch beyond the neutron star branch. Compact stars in the third family
branch may contain pure color superconducting core and have radii smaller than
those of the neutron star branch. Our results are compared with the recent
observations on RX J185635-3754 and the recently measured mass-radius
relationship by X-ray Multi Mirror-Newton Observatory.


title:
The thin layer of Warm Ionized Gas: towards a 3-D reconstruction of the
  spatial distribution of HII regions

abstract:
  HII regions are known to contribute to the so-called thin layer of the
diffuse Warm Ionized Gas. In order to constrain this contribution, we
reconstruct the 3-D distribution of the sources. A detailed spatial analysis of
the largest up-to-date sample of HII regions is presented.


title: Highest Energy Neutrino Showers in EUSO

abstract:
  EUSO experiment, while monitoring the downward Earth atmosphere layers, may
observe among common Ultra High Energy Cosmic Rays, UHECR, also High Energy
Neutrino-Induced Showers either blazing upward to the detectors at high (PeVs)
energies or at much higher GZK E >= 10^19 eV energies, showering horizontally
in air or vertically downward. A small fraction of these upward, horizontal and
vertical Shower maybe originated by direct astrophysical UHE neutrino
interacting on terrestrial air layers itself; however the dominant UHE neutrino
signal are Upward and Horizontal Tau Air-Showers, UPTAUS and HORTAUs (or Earth
skimming neutrinos), born within widest Earth Crust Crown (Sea or Rock) Areas,
by UHE nu_tau + Nuclei--> tau interactions, respectively at PeVs and GZK
energies: their rate and signatures are shown in a neutrino fluence map for
EUSO thresholds versus other UHE air interacting neutrino signals and
backgrounds. The effective target Masses originating HORTAUs seen by EUSO may
exceed (on sea) at 10^19 eV energy a wide and huge ring volume above
1/2*A_Euso*l_tau*(L_nu/2R_Earth)^2= 5130 km^3.
  The consequent HORTAUS event rate (even at 10% EUSO duty cycle lifetime) may
deeply test the expected Z-Burst models by at least a hundred of yearly events.
Even rarest but inescapable GZK neutrinos (secondary of photopion production of
observed cosmic UHECR) might be discovered in a few (or a tens) horizontal
shower events; in this view an extension of EUSO detectability up to E > 10^19
eV threshold is to be preferred. A wider collecting EUSO telescope (3m
diameter) might be considered.


title: Constraining the dark energy with Ly-alpha forest

abstract:
  Statistical properties of gas absorption in high redshift quasars such as
power spectrum and bispectrum allow one to determine the evolution of structure
over the redshift range 2<z<4. Sloan Digital Sky Survey (SDSS) will measure
around 10,000 quasar spectra in this redshift range and will allow one to
determine the growth factor with a few percent accuracy. This allows one to
extend the studies of dark energy to higher redshift and determine the presence
of dark energy if Omega_de>0.1-0.2 at z>2. In combination with low redshift
studies one can place useful limits on the time evolution of the equation of
state.


title:
Models for Evolution of Dusty Galaxies and E/S0s Seen in Multiband
  Surveys

abstract:
  Phenomenological models for evolution of dusty galaxies and E/S0 galaxies,
respectively, are developed to address two major questions concenring galaxy
populations in deep infrared (IR) surveys: (1) Do normal late-type galaxies or
starburst galaxies (including galaxies with obscured AGNs) dominate among
sources in deep IR surveys? (2) How much do E/S0 galaxies contribute to the
counts in deep mid-infrared (MIR: 3 -- 20$\mu m$) surveys? Among three new
models for evolution of dusty galaxies, it is assumed in Model S1 that
starburst galaxies are the dominant population, and in Model S2 that normal
galaxies dominate. Model S3 is an intermediate model. Comparing the model
predictions with a wide range of observational data collected from the
literature, we find that none of these models can be ruled out, given the
uncertainties of the data. We show that the most direct method to distinguish
these models is to compare the predicted color distributions of IR galaxies
with observations, which will soon be available from the SWIRE survey. The
models for E/S0 galaxies follow a simple passive evolution approach. Among the
three E/S0 models (E1, E2 and E3) investigated in this paper, Model E2 which is
specified by a peak formation redshift $z_{peak}=2$, and an e-folding formation
time scale $\omega=2$ Gyr, fits the data best. This suggests a synchronization
between the evolution of E/S0 galaxies and of starburst galaxies, in the sense
that the peak of the formation function of E/S0s ($z_{peak}=2$) is close to the
peak of the evolution functions of starburst galaxies ($z_{peak} = 1.4$). New
predictions for counts and confusion limits in the SIRTF bands are presented.


title: Nanolensing of gamma-ray bursts

abstract:
  All quasars vary in their optical flux on a time-scale of years, and it has
been proposed that these variations are principally due to gravitational
lensing by a cosmologically distributed population of planetary mass objects.
This interpretation has implications for the observable properties of gamma-ray
bursts (GRBs) -- as a source expands across the nano-arcsecond caustic network,
variability is expected -- and data on GRBs can be used to test the proposed
model of quasar variability. Here we employ an ultra-relativistic blast-wave
model of the source, with no intrinsic variations, to study the effects of
nanolensing on GRBs. Taken in isolation the light-curves of the caustic
crossings are predictable, and we find that a subset of the predicted
light-curves (the image-annihilating fold crossings) resemble the ``pulses''
which are commonly seen in long GRBs. Furthermore, for sources at high redshift
the expected time between caustic crossings is of order seconds, comparable to
the observed time between pulses. These points suggest that it might be
possible to model some of the observed variations of GRBs in terms of
nanolensing; however, our simulated light-curves exhibit a small depth of
modulation compared to what is observed. This means that the GRB data do not
significantly constrain the quasar nanolensing model; it also means that the
simplest nanolensing model cannot explain the observed GRB ``pulses''. Viable
nanolensing models for pulses probably require a large external beam shear. If
a viable model can be constructed it would effect a considerable simplification
in source modelling and, ironically, it would explain why no macro-lensed GRBs
have been identified to date.
  (Abridged)


title: Magnetogenesis, variation of gauge couplings and inflation

abstract:
  The interplay among the possible variation of gauge coupling and the
inflationary dynamics is investigated in a simplified toy model. Depending upon
various parameters (scalar mass, curvature scale at the end of inflation and at
the onset of the radiation epoch), the two-point function of the magnetic
inhomogeneities grows during the de Sitter stage of expansion and,
consequently, large scale magnetic fields are generated. The requirements
coming from inflationary magnetogenesis are examined together with the
theoretical constraints stemming from the explicit model of the evolution of
the gauge coupling.


title: Status of the KASCADE-Grande Experiment

abstract:
  The status and capabilities of the KASCADE-Grande extensive air shower
experiment are presented. The installation is located at Forschungszentrum
Karlsruhe and comprises a large collecting area (0.5 km^2) electromagnetic
array (Grande) operated jointly with the existing KASCADE detectors.
KASCADE-Grande will cover the primary energy range 10^16 eV < E_0 < 10^18 eV
overlapping with KASCADE around 10^16 eV, thus providing continuous information
on the primary energy and mass of cosmic rays from 3x10^14 eV up to 10^18 eV.
The major goal of the measurements is the unambiguous observation of the``iron
knee'' expected in the cosmic ray spectrum at E_k^{Fe} ~ 10^17 eV.


title: The Chemical Composition of Cosmic Rays

abstract:
  A brief review about the chemical composition of cosmic rays in the energy
range 10^15 < E < 10^20 eV is given. While there is convincing evidence for an
increasingly heavier composition above the knee, no clear picture has emerged
at the highest energies, yet. We discuss implications about the origin of
cosmic rays and emphasize systematic differences related to data analysis
techniques and to the limited understanding of the air shower development.


title: Faint and peculiar objects in GAIA: results from GSC-II

abstract:
  The one billion objects in the GSC-II make up a formidable data set for the
hunt of peculiar and rare targets such as late type stars, white dwarfs, carbon
dwarfs, asteroids, variable stars, etc. Here we present a survey to search for
ancient cool white dwarfs, which led to the discovery of several stars with
peculiar spectral distributions and extreme physical properties. Finally, we
discuss the impact of the GAIA mission with respect to these peculiar and faint
white dwarfs.


title:
An ESO/VLT survey of NIR (Z<=25) selected galaxies at redshifts 4.5<z<6:
  constraining the cosmic star formation rate near the reionization epoch

abstract:
  We present the results of a VLT and HST imaging survey aimed at the
identification of 4.5<z<6 galaxies. In the VLT data, a set of broad and
intermediate band filters has been used to select 13 high--$z$ candidates in a
Z(AB)<25 catalog, over an area of about 30 arcmin2. Discrimination against
lower redshift interlopers (mainly early--type galaxies at high redshift and
cool Galactic stars) has been done combining morphological and spectral
classification. This sample has been combined with a deeper I<27.2 sample
obtained from the Hubble Deep Field campaigns. The VLT final sample consists of
13 high z candidates, 4 of which are identified with high confidence as z>4.5
galaxies. The resulting integral surface density of the Z<25 candidates at
z>4.5z is in the range 0.13-0.44/arcmin^2 and that in the highest redshift bin
5<z<6 is between 0.07-0.13/arcmin^2. In the two HDFs, we identify at I<27.2 25
galaxies in the range 4.5<z<5 and 16 at 5<z<6$, corresponding to surface
densities of 3.1 arcmin^-2 and 2 arcmin^-2, respectively. We show that the
observed Z<25 UV luminosity density appear to drop by about one order of
magnitude from z~3 to z~6. However, if we apply a threshold to obtain an
absolute--magnitude limited sample, the UV luminosity density results to be
roughly constant up to z~6. We finally show that recent semi-analytic
hierarchical models for galaxy formation, while predicting a nearly constant
total UV luminosity density up to z~6, under-predict the observed UV luminosity
density at Z<25 and over-predicts the I<27.2 one. This behaviour can be
understood in term of a poor match to the slope of the UV luminosity function.


title: Galaxy structure and kinematics towards the NGP

abstract:
  We present a proper motion survey over about 200 square degrees towards the
NGP, based on the material used for the construction of the GSC-II, that we are
using to study the vertical structure and kinematics of the Galaxy. In
particular, we measured the rotation velocity of the halo up to 10 kpc above
the galactic plane traced by a sample of RR Lyr{\ae} and BHB giants for which
radial velocities were used to recover the complete distribution of the spatial
velocities. Finally, the impact of astrometric and spectroscopic GAIA
observation are discussed.


title: On particle acceleration around shocks. I

abstract:
  We derive a relativistically covariant (although not manifestly so) equation
for the distribution function of particles accelerated at shocks, which applies
also to extremely relativistic shocks, and arbitrarily anisotropic particle
distributions. The theory is formulated for arbitrary pitch angle scattering,
and reduces to the well--known case for small angle scatterings via a
Fokker--Planck approximation. The boundary conditions for the problem are
completely reformulated introducing a physically motivated Green's function;
the new formulation allows derivation of the particle spectrum both close and
far away from the injection energy in an exact way, while it can be shown to
reduce to a power--law at large particle energies. The particle spectral index
is also recovered in a novel way. Contact is made with the Newtonian treatment.


title:
Chandra Studies of Nonthermal Emission from Supernova Remnants and
  Pulsar Wind Nebulae

abstract:
  While supernova remnants (SNRs) have long been considered prime candidates as
sources of cosmic rays, it is only recently that X-ray observations have
identified several shell-type SNRs dominated by nonthermal emission, thus
revealing shock-accelerated electrons with energies extending far beyond the
typical thermal spectrum. Two of these SNRs have been detected as sources of
VHE gamma-rays.In other remnants, discrepancies between the shock velocity and
the electron temperature point to a strong cosmic ray component that has
thrived at the expense of the thermal gas. Modeling of the radio, X-ray, and
gamma-ray emission provides constraints on particle acceleration as well as the
properties of the medium in which the mechanism prospers.
  Crab-like pulsar wind nebulae (PWNe) are characterized by a termination shock
at which the wind is forced to join the slow expansion of the outer nebula.
These shocks also act as sites in which particles are boosted to high energies;
the X-ray emission from the Crab Nebula, as well as the inverse Compton
radiation observed as VHE gamma-rays, imply electrons with energies in excess
of ~100 TeV. Recent X-ray observations have begun to reveal these shock zones
in the Crab and other PWNe, and are now allowing us to constrain the nature of
pulsar winds as well as the flow conditions in the outer nebulae. Here I
present a brief overview of recent studies with the Chandra X-ray Observatory
in which the properties of these shock acceleration regions are finally being
revealed.


title:
Far-Ultraviolet & Halpha Spectroscopy of SNR0057-7226 in the SMC HII
  Region N66

abstract:
  N66/NGC346 is the largest and brightest HII region in the Small Magellanic
Cloud and contains at least one known supernova remnant SNR0057-7226. Optical
emission from the remnant is overwhelmed by the bright photoionized emission
from the nebula, but the remnant has been detected by way of far ultraviolet
absorption lines. Here we present data from the Far Ultraviolet Spectroscopic
Explorer (FUSE) satellite showing strong OVI and CIII emission from a position
at the edge of SNR0057-7226. We also present high-resolution, long-slit Halpha
spectra across N66 showing high- and low-velocity emission corresponding
closely to the X-ray boundaries of the supernova remnant. We use these FUV and
optical data to determine the physical parameters of the shock and interaction
geometry with N66. We find that ionizing photons from the many massive cluster
stars nearby likely affect the ionization balance in the post-shock gas,
hindering the production of lower-ionization and neutral species. We discuss
the importance and inherent difficulty of searching for supernova remnants in
or near bright HII regions and suggest that the far ultraviolet provides a
viable means to discover and study such remnants.


title: The Galaxy Proximity Effect in the Lyman-alpha Forest

abstract:
  Hydrodynamic cosmological simulations predict that the average opacity of the
Ly-alpha forest should increase in the neighborhood of galaxies because
galaxies form in dense environments. Recent observations (Adelberger et al.
2002) confirm this expectation at large scales, but they show a decrease of
absorption at comoving separations Delta_r <~ 1 Mpc/h. We show that this
discrepancy is statistically significant, especially for the innermost data
point at Delta_r <= 0.5 Mpc/h, even though this data point rests on three
galaxy-quasar pairs. Galaxy redshift errors of the expected magnitude are
insufficient to resolve the conflict. Peculiar velocities allow gas at comoving
distances >~ 1 Mpc/h to produce saturated absorption at the galaxy redshift,
putting stringent requirements on any ``feedback'' solution. Local
photoionization is insufficient, even if we allow for recurrent AGN activity
that keeps the neutral hydrogen fraction below its equilibrium value. A simple
``wind'' model that eliminates all neutral hydrogen in spheres around the
observed galaxies can marginally explain the data, but only if the winds extend
to comoving radii ~1.5 Mpc/h.


title: Galaxy Clustering and Galaxy Bias in a Lambda-CDM Universe

abstract:
  We investigate galaxy clustering and galaxy-mass correlations in the LCDM
cosmological model using a large volume SPH simulation. For the most part, the
predicted biases between galaxies and dark matter lead to good agreement with
current observations, including: (1) a nearly constant comoving correlation
length from z=3 to z=0 for mass-selected galaxy samples of constant comoving
space density; (2) an rms bias factor b~1 at z=0; (3) a scale-dependent bias on
small scales that transforms the curved dark matter correlation function into a
nearly power-law galaxy correlation function; (4) galaxy pairwise dispersion
and hierarchical skewness ratio S_3 in good agreement with observed values, and
lower than values for the dark matter by ~20%; (5) a ratio of galaxy-galaxy to
galaxy-mass correlation functions consistent with recent measurements from the
RCS survey; and (6) a mean excess mass dM(260/h kpc) approximately proportional
to galaxy baryon mass M_b, in agreement with lensing estimates from the SDSS.
These clustering properties vary with galaxy baryon mass and, more strongly,
with stellar population age, in good qualitative agreement with the observed
dependence of galaxy clustering and galaxy-mass correlations on galaxy type.
The predicted ratio dM(260)/M_b is lower than the SDSS estimates for galaxies
with M_b>~2e11 Msun, but numerical resolution effects account for most of this
discrepancy, leaving little room for feedback or other astrophysical processes
to reduce the stellar masses of luminous galaxies, at least given our adopted
cosmological parameters. Our results show that the LCDM model and the galaxy
formation physics incorporated in the SPH simulation give a good account of
observed galaxy clustering, but anticipated improvements in clustering and weak
lensing measurements will soon test this picture in much more detail.


title: The Halo Occupation Distribution and the Physics of Galaxy Formation

abstract:
  The halo occupation distribution (HOD) describes the bias between galaxies
and dark matter by specifying (a) the probability P(N|M) that a halo of virial
mass M contains N galaxies of a particular class and (b) the relative
distributions of galaxies and dark matter within halos. We calculate predicted
HODs for a Lambda-CDM cosmological model using an SPH hydrodynamic simulation
and a semi-analytic (SA) galaxy formation model. Although the two methods
predict different galaxy mass functions, their HOD predictions agree remarkably
well. For mass-selected samples, the mean occupation <N(M)> exhibits a sharp
cutoff at low halo masses, a slowly rising plateau for <N>~1-2, and a more
steeply rising high occupancy regime. At low <N>, the mean pair and triple
counts are well below Poisson expectations, with important consequences for
small scale behavior of 2- and 3-point correlation functions. The HOD depends
strongly on galaxy age, with high mass halos populated mainly by old galaxies
and low mass halos by young galaxies. The SPH simulation supports several
simplifying assumptions about HOD bias: the most massive galaxy in a halo
usually lies close to the center and moves near the halo's mean velocity;
satellite galaxies have the same radial profile and velocity dispersion as the
dark matter; and the mean occupation at fixed halo mass is independent of the
halo's larger scale environment. By applying the SPH and SA HODs to a large
volume N-body simulation, we show that both methods predict slight, observable
departures from a power-law galaxy correlation function. The predicted HODs are
closely tied to the underlying galaxy formation physics, they offer useful
guidance to theoretical models of galaxy clustering, and they will be tested
empirically by ongoing analyses of galaxy redshift surveys. (Shortened)


title: Could Dark Energy be Measured from Redshift Surveys ?

abstract:
  We review the ability of redshift surveys to provide constraints on the Dark
Energy content of the Universe. The matter power spectrum and dynamics at the
present epoch are nearly `blind' to Dark Energy, but combined with the CMB they
can provide a constraint on the Equation of State parameter w. A representative
result from the 2dF galaxy redshift survey combined with the CMB is w <-0.52
(95 % CL; with a prior of w >= -1), consistent with Einstein's Cosmological
Constant model (w=-1). More complicated forms of Quintessence (e.g.
epoch-dependent w or w<-1) are not yet ruled out. At higher redshifts, the
abundance of galaxies and clusters of galaxies, variants of the
Alcock-Paczynski curvature test and cross correlation of the CMB with radio
sources look potentially promising, but they suffer from degeneracy with other
parameters such as the matter density and galaxy biasing.


title: Fragmentation and Collapse of Turbulent Molecular Clouds

abstract:
  We performed simulations of self-gravitating hydrodynamic turbulence to model
the formation of filaments, clumps and cores in molecular clouds. We find that
when the mass on the initial computational grid is comparable to the Jeans
mass, turbulent pressure is able to prevent gravitational collapse. When the
turbulence has damped away sufficiently, gravitational collapse can occur, and
the resulting structure closely resembles the pre-singularity collapse of an
isothermal sphere of Penston (1969). If several Jeans masses are initially
placed on the grid, turbulence may not be sufficient to prevent collapse before
turbulence can be significantly damped. In this case, the cores have density
structures which are considerably shallower than expected for an isothermal
gas, and resemble the solutions for a logatropic equation of state.


title:
Probing the Friedmann equation during recombination with future CMB
  experiments

abstract:
  We show that by combining measurements of the temperature and polarization
anisotropies of the Cosmic Microwave Background (CMB), future experiments will
tightly constrain the expansion rate of the universe during recombination. A
change in the expansion rate modifies the way in which the recombination of
hydrogen proceeds, altering the shape of the acoustic peaks and the level of
CMB polarization. The proposed test is similar in spirit to the examination of
abundances of light elements produced during Big Bang Nucleosynthesis and it
constitutes a way to study possible departures from standard recombination. For
simplicity we parametrize the change in the Friedmann equation by changing the
gravitational constant $G$. The main effect on the temperature power spectrum
is a change in the degree of damping of the acoustic peaks on small angular
scales. The effect can be compensated by a change in the shape of the
primordial power spectrum. We show that this degeneracy between the expansion
rate and the primordial spectrum can be broken by measuring CMB polarization.
In particular we show that the MAP satellite could obtain a constraint for the
expansion rate $H$ during recombination of $\delta H/H \simeq 0.09$ or $\delta
G/G \simeq 0.18$ after observing for four years, whereas Planck could obtain
$\delta H/H \leq 0.014$ or $\delta G/G \leq 0.028$ within two years, even after
allowing for further freedom in the shape of the power spectrum of primordial
fluctuations.


title: Non-LTE line-formation for CNO

abstract:
  Accurate atomic data have become available in the recent past due to the
demands of astrophysics and fusion research. We report on the impact of such
data on non-LTE line-formation calculations for CNO in early-type stars.
Considerable improvement is achieved by the derivation of consistent results
from practically all available spectroscopic indicators, regardless of
ionization stage or spin system, and the uncertainties in the analyses are
drastically reduced. Moreover, systematic trends are revealed, e.g. an increase
of the NI abundances from previous studies of BA-type supergiants by a factor
of two is indicated. The present work promises stringent observational
constraints on chemical mixing in the course of massive star evolution. First
results on BA-type supergiants in the Galaxy and the Magellanic Clouds are
discussed.


title:
An Automatic Image Reduction Pipeline for the Advanced Camera for
  Surveys

abstract:
  We have written an automatic image processing pipeline for the Advanced
Camera for Surveys (ACS) Guaranteed Time Observation (GTO) program. The
pipeline, known as Apsis, supports the different cameras available on the ACS
instrument and is written in Python with a flexible object-oriented design that
simplifies the incorporation of new pipeline modules. The processing steps
include empirical determination of image offsets and rotation, cosmic ray
rejection, image combination using the drizzle routine called via the STScI
Pyraf package, object detection and photometry using SExtractor, and
photometric redshift estimation in the event of multiple bandpasses. The
products are encapsulated in XML markup for automated ingestion into the ACS
Team archive.


title: The Amplitude of Mass Fluctuations

abstract:
  We determine the linear amplitude of mass fluctuations in the universe,
sigma_8, from the abundance of massive clusters at redshifts z=0.5 to 0.8. The
evolution of massive clusters depends exponentially on the amplitude of mass
fluctuations and thus provides a powerful measure of this important
cosmological parameter. The relatively high abundance of massive clusters
observed at z>0.5, and the relatively slow evolution of their abundance with
time, suggest a high amplitude of mass fluctuations: sigma_8=0.9 +-10% for
Omega_m=0.4, increasing slightly to sigma_8=0.95 for Omega_m=0.25 and
sigma_8=1.0 for Omega_m=0.1 (flat CDM models). We use the cluster abundance
observed at z=0.5 to 0.8 to derive a normalization relation from the
high-redshift clusters, which is only weakly dependent on Omega_m:
sigma_8*Omega_m^0.14 = 0.78 +-0.08. When combined with recent constraints from
the present-day cluster mass function (sigma_8*Omega_m^0.6=0.33 +-0.03) we find
sigma_8=0.98 +-0.1 and Omega_m=0.17 +-0.05. Low sigma_8 values (<0.7) are
unlikely; they produce an order of magnitude fewer massive clusters than
observed.


title: s-Process Nucleosynthesis in AGB Stars: A Test for Stellar Evolution

abstract:
  [abridged] We study the s-process in AGB stars using three different stellar
evolutionary models computed for a 3Msun and solar metallicity star. First we
investigate the formation and the efficiency of the main neutron source. We
parametrically vary the number of protons mixed from the envelope into the C12
rich core. For p/C12 > 0.3, mainly N14 is produced, which represent a major
neutron poison. The amount of C12 in the He intershell and the maximum value of
the time-integrated neutron flux are proportional. Then we generate detailed
s-process calculations on the basis of stellar evolutionary models constructed
with three different codes. One code considers convective hydrodynamic
overshoot that depends on a free parameter f, and results in partial mixing
beyond convective boundaries, the most efficient third dredge up and the
formation of the C13 pocket. For the other two codes an identical C13 pocket is
introduced in the post-processing nucleosynthesis calculations. The models
generally reproduce the spectroscopically observed s-process enhancements. The
results of the cases without overshoot are remarkably similar. The code
including hydrodynamic overshoot produces a He intershell composition near to
that observed in H-deficient central stars of planetary nebulae. As a result of
this intershell dredge up the neutron fluxes have a higher efficiency, both
during the interpulse periods and within thermal pulses. The s-element
distribution is pushed toward the heavier s-process elements and large
abundances of neutron-rich isotopes fed by branching points in the s-process
path are produced. Several observational constraints are better matched by the
models without overshoot. Our study need to be extended to different masses and
metallicities and in the space of the free overshoot parameter f.


title: Particle acceleration in the M87 jet

abstract:
  The wealth of high quality data now available on the M87 jet inspired us to
carry out a detailed analysis of the plasma physical conditions in the jet. In
a companion paper (Lobanov, Hardee & Eilek, this proceedings) we identify a
double-helix structure within the jet, and apply Kelvin-Helmholtz stability
analysis to determine the physical state of the jet plasma. In this paper we
treat the jet as a test case for in situ particle acceleration. We find that
plasma turbulence is likely to exist at levels which can maintain the energy of
electrons radiating in the radio to optical range, consistent with the
broadband spectrum of the jet.


title: CNO in Low- and Zero-Metallicity AGB Stars

abstract:
  The oldest stars hide information about the chemical evolution of the early
universe. In this contect new models of the AGB stellar evolution phase at very
low and zero metallicity are presented. Due to the deficiency or absence of CNO
catalytic material hydrogen burning operates at significantly higher
temperatures than in stars of higher metallicity. As a result convective mixing
plays a very important role since the nuclear burning shells are not well
separated by an entropy barrier. These stars can host flash-like burning events
induced by mixing of C12 and protons at the core-envelope interface. Three
different mixing events with proton-capture nucleosynthesis can be encountered.
One of them, the hot dredge-up, is reported here for the first time. All these
specific modes of nucleosynthesis are relevant for the production of CNO
material in the first intermediate mass stars.


title: Radiation of Neutron Stars Produced by Superfluid Core

abstract:
  We find that neutron star interior is transparent for collisionless electron
sound, the same way as it is transparent for neutrinos. In the presence of
magnetic field the electron sound is coupled with electromagnetic radiation and
form the fast magnetosonic wave. We find that electron sound is generated by
superfluid vortices in the stellar core. Thermally excited helical vortex waves
produce fast magnetosonic waves in the stellar crust which propagate toward the
surface and transform into outgoing electromagnetic radiation. The vortex
radiation has the spectral index -0.45 and can explain nonthermal radiation of
middle-aged pulsars observed in the infrared, optical and hard X-ray bands. The
radiation is produced in the stellar interior which allows direct determination
of the core temperature. Comparing the theory with available spectra
observations we find that the core temperature of the Vela pulsar is T=8*10^8K,
while the core temperature of PSR B0656+14 and Geminga exceeds 2*10^8K. This is
the first measurement of the temperature of a neutron star core. The
temperature estimate rules out equation of states incorporating Bose
condensations of pions or kaons and quark matter in these objects. Based on the
temperature estimate and cooling models we determine the critical temperature
of triplet neutron superfluidity in the Vela core Tc=(7.5\pm 1.5)*10^9K which
agrees well with recent data on behavior of nucleon interactions at high
energies. Another finding is that in the middle aged neutron stars the vortex
radiation, rather then thermal conductivity, is the main mechanism of heat
transfer from the stellar core to the surface. Electron sound opens a
perspective of direct spectroscopic study of superdense matter in the neutron
star interiors.

categories: astro-ph cond-mat.supr-con gr-qc nucl-th


title: Evidence for Core Collapse in the Type Ib/c SN 1999ex

abstract:
  We present optical and infrared spectra of SN 1999ex that reveal a clear
example of an intermediate Type Ib/c case. This suggests a continuous
spectroscopic sequence between Type Ib and Type Ic supernovae. We report UBVRIz
photometric observations of SN 1999ex that started only one day after
explosion, which permitted us to witness an elusive transient cooling phase
that lasted 4 days. The initial cooling and subsequent radioactive heating
produced a dip in the lightcurve which is consistent with explosion models
involving core collapse of evolved massive helium stars, and inconsistent with
lightcurves resulting from the thermonuclear runaway of compact white dwarfs.


title: Dark Energy and the Hubble Age

abstract:
  I point out that an effective upper limit of approximately 20 Gyr (for a
Hubble constant of 72 km/s/Mpc) or alternatively on the $H_0$-independent
quantity $H_0t_0 < 1.47$, exists on the age of the Universe, essentially
independent of the unknown equation of state of the dominant dark energy
component in the Universe. Unless astrophysical constraints on the age of the
Universe can convincingly reduce the upper limit to below this value no useful
lower limit on the equation of state parameter $w$ for this component can be
obtained. Direct dating by stars does not provide a useful constraint, but
model-dependent cosmological limits from supernovae and the CMB observations
may. For a constant value of $w$, a bound $H_0t_0 < 1.1$ gives a limit $ w>
-1.5$


title: Spectra and power of relativistic jets

abstract:
  The power of blazar jets rivals the power that gravity can extract from
accreting matter. The mechanism launching and accelerating jets can be
considered as the most efficient engine operating in radio--loud sources. It is
still a matter of debate if the jet carries this power to the radio lobes,
hundreds of kpc away, in the form of Poynting flux or bulk kinetic energy, or
both, and if these two ingredients have relative weights changing along the
way. Accordingly, there are two (or more) possible general scenarios for how
the jet can dissipate part of its power into radiation. It can be through e.g.
reconnection of the magnetic field in the purely electromagnetic scenario, or
through internal shocks in the matter dominated picture. Ways to discriminate
these ideas are welcome.


title: Dynamics of inflationary cosmology in TVSD model

abstract:
  Within the framework of a model Universe with time variable space dimensions
(TVSD), known as decrumpling or TVSD model, we study TVSD chaotic inflation and
obtain dynamics of the inflaton, scale factor and spatial dimension. We also
study the quantum fluctuations of the inflaton field and obtain the spectral
index and its running in this model. Two classes of examples have been studied
and comparisons made with the standard slow-roll formulae. We compare our
results with the recent Wilkinson Microwave Anisotropy Probe (WMAP) data.


title:
The incompatibilities between the standard theory of interstellar
  extinction and observations

abstract:
  In this paper I review a series of observations which do not agree with the
standard interpretation of the extinction curve. The consequence is that light
we receive from a reddened star must be contaminated by starlight scattered at
very small angular distances from the star. The true extinction curve is a
straight line from the near infrared to the far-UV. If so, all interstellar
grains models must be questionned. Another conclusion concerns the average
properties of interstellar grains which seem much more uniform than previously
thought.


title:
A review of the properties of the scattered starlight which contaminates
  the spectrum of reddened stars

abstract:
  When a star is observed behind an interstellar cloud of sufficient column
density, we do not observe the direct light from the star, which is totally
extinguished. Rather, we see only starlight scattered at small angles from the
star.
  I use several papers published in New Astronomy to recount the different
steps which permit understanding how, and under which conditions, scattered
starlight can be more important than direct starlight in the spectrum of a
reddened star. Associated problems -the fit of the extinction curve, the nature
of the scatterers (small grains, or, atoms or molecules from the gas), the
2200A bump- are also, briefly, discussed.


title:
The conditions for coherent scattering of starlight in the forward
  direction, and it's consequences

abstract:
  I have been too conservative in `A review of the properties of the scattered
starlight which contaminates the spectrum of reddened stars' (NewA, 2002, 7/4,
191) concerning the conditions implied by an additional component of scattered
light in the spectrum of reddened stars. I will review and simplify these
conditions. Implications for the column density of the scatterers will then be
discussed. Estimates for coherent Rayleigh scattering by hydrogen are in
excellent agreement with the observations.


title:
The 2dF Galaxy Redshift Survey: correlation functions, peculiar
  velocities and the matter density of the Universe

abstract:
  We present a detailed analysis of the two-point correlation function, from
the 2dF Galaxy Redshift Survey (2dFGRS). We estimate the redshift-space
correlation function, xi(s), from which we measure the redshift-space
clustering length, s_0=6.82+/-0.28 Mpc/h. We also estimate the projected
correlation function, Xi(sigma), and the real-space correlation function,
xi(r), which can be fit by a power-law, with r_0=5.05+/-0.26Mpc/h,
gamma_r=1.67+/-0.03. For r>20Mpc/h, xi drops below a power-law as is expected
in the popular LCDM model. The ratio of amplitudes of the real and
redshift-space correlation functions on scales of 8-30Mpc/h gives an estimate
of the redshift-space distortion parameter beta. The quadrupole moment of xi on
scales 30-40Mpc/h provides another estimate of beta. We also estimate the
distribution function of pairwise peculiar velocities, f(v), including
rigorously the effect of infall velocities, and find that it is well fit by an
exponential. The accuracy of our xi measurement is sufficient to constrain a
model, which simultaneously fits the shape and amplitude of xi(r) and the two
redshift-space distortion effects parameterized by beta and velocity
dispersion, a. We find beta=0.49+/-0.09 and a=506+/-52km/s, though the best fit
values are strongly correlated. We measure the variation of the peculiar
velocity dispersion with projected separation, a(sigma), and find that the
shape is consistent with models and simulations. Using the constraints on bias
from recent estimates, and taking account of redshift evolution, we conclude
that beta(L=L*,z=0)=0.47+/-0.08, and that the present day matter density of the
Universe is 0.3, consistent with other 2dFGRS estimates and independent
analyses.