title:
Grid-based simulation program for gravitational wave interferometers
  with realistically imperfect optics

abstract:
  We describe an optical simulation program that models a complete,
coupled-cavity interferometer like those used by the Laser Interferometer
Gravitational-Wave Observatory (LIGO) Project. A wide variety of interferometer
deformations can be modeled, including general surface roughness and substrate
inhomogeneities, with no a priori symmetry assumptions about the nature of
interferometer imperfections. Several important interferometer parameters are
optimized automatically to achieve the best possible sensitivity for each new
set of perturbed mirrors. The simulation output data set includes the
circulating powers and electric fields at various points in the interferometer,
both for the main carrier beam and for its signal-sideband auxiliary beams,
allowing an explicit calculation of the shot-noise-limited gravitational-wave
sensitivity of the interferometric detector to be performed. Here we present an
overview of the physics simulated by the program, and demonstrate its use with
a series of runs showing the degradation of LIGO performance caused by
realistically-deformed mirror profiles. We then estimate the effect of this
performance degradation upon the detectability of astrophysical sources of
gravitational waves. We conclude by describing applications of the simulation
program to LIGO research and development efforts.


title: Polarizing Grids, Their Assemblies and Beams of Radiation

abstract:
  This article gives an analysis of the behavior of polarizing grids and
reflecting polarizers by solving Maxwell's equations, for arbitrary angles of
incidence and grid rotation, for cases where the excitation is provided by an
incident plane wave or a beam of radiation. The scattering and impedance matrix
representations are derived and used to solve more complicated configurations
of grid assemblies. The results are also compared with data obtained in the
calibration of reflecting polarizers at the Owens Valley Radio Observatory
(OVRO). From this analysis, we propose a method for choosing the optimum grid
parameters (wire radius and spacing). We also provide a study of the effects of
two types of errors (in wire separation and radius size) that can be introduced
in the fabrication of a grid.


title: PSR J1909-3744, a Binary Millisecond Pulsar with a Very Small Duty Cycle

abstract:
  We report the discovery of PSR J1909-3744, a 2.95 millisecond pulsar in a
nearly circular 1.53 day orbit. Its narrow pulse width of 43 microseconds
allows pulse arrival times to be determined with great accuracy. We have
spectroscopically identified the companion as a moderately hot (T = 8500 K)
white dwarf with strong absorption lines. Radial velocity measurements of the
companion will yield the mass ratio of the system. Our timing data suggest the
presence of Shapiro delay; we expect that further timing observations, combined
with the mass ratio, will allow the first accurate determination of a
millisecond pulsar mass. We have measured the timing parallax and proper motion
for this pulsar which indicate a transverse velocity of 140 (+80/-40) km/s.
This pulsar's stunningly narrow pulse profile makes it an excellent candidate
for precision timing experiments that attempt to detect low frequency
gravitational waves from coalescing supermassive black hole binaries.


title:
Controlling a Telescope Chopping Secondary Mirror Assembly Using a
  Signal Deconvolution Technique

abstract:
  We describe a technique for improving the response of a telescope chopping
secondary mirror assembly by using a signal processing method based on the Lucy
deconvolution technique. This technique is general and could be used for any
systems, linear or non-linear, where the transfer function(s) can be measured
with sufficient precision. We demonstrate how the method was implemented and
show results obtained at the Caltech Submillimeter Observatory using different
chop throw amplitudes and frequencies. No intervention from the telescope user
is needed besides the selection of the chop throw amplitude and frequency. All
the calculations are done automatically once the appropriate command is issued
from the user interface of the observatory's main computer.


title: Broad Recombination Line Objects in W49N on 600 AU Scales

abstract:
  High resolution 7 mm observations of the W49N massive star forming region
have detected recombination line emission from the individual ultracompact (UC)
HII regions on 50 milliarcsecond (600 AU) scales. These line observations,
combined with multifrequency, high-resolution continuum imaging of the region
at 7 mm (VLA) and at 3 mm and 1 mm (BIMA), indicate that five to seven of the
eighteen ultracompact sources in W49N are broad recombination line objects
(BRLOs) as described by Jaffe & Martin-Pintado (1999). BRLOs have both broad
radio recombination lines ($\Delta$V$>$60 \kms) and rising spectra
(S$_{\nu}\sim\nu^{\alpha}$), with $\alpha$ values greater than 0.4. The broad
line widths of the H52$\alpha$ line are probably related to motions in the
ionized gas rather than pressure broadening. A number of models have been
proposed to explain the long lifetime of UC HII regions, including the
photoevaporated disk model proposed by Hollenbach et al. (1994). This model can
also explain the broad lines, rising spectra and bipolar morphologies of some
sources. We suggest$-$based on line and continuum observations as well as
source morphology$-$that in a subset of the W49N ultracompact sources we may be
observing ionized winds that arise from circumstellar disks.


title:
Low frequency observations of SN 1993J with Giant Meterwave Radio
  Telescope

abstract:
  In this paper, we discuss the low frequency spectrum of SN 1993J with GMRT.
We observed SN 1993J at several epochs in 20cm, 50cm, 90cm and 125cm
wavelengths and achieved near simultaneous spectra. We fit synchrotron self
absorption (SSA) and free-free models to the data. We compare the size of SN
obtained using SSA fits to that of size extrapolated from VLBI measurements at
various epochs using public data at earlier epochs. We find that the
synchrotron self absorption process is insufficient to reproduce the observed
size of the supernova under the assumption of equipartition between magnetic
fields and relativistic electrons. We also derive the evolution of spectral
index and magnetic field at several epochs.


title: Low frequency radio and X-ray properties of core-collapse supernovae

abstract:
  Radio and X-ray studies of young supernovae probe the interaction between the
supernova shock waves and the surrounding medium and give clues to the nature
and past of the progenitor star. Here we discuss the early emission from type
Ic SN 2002ap and argue that repeated Compton boosting of optical photons by hot
electrons presents the most natural explanation of the prompt X-ray emission.
We describe the radio spectrum of another type Ic SN 2003dh (GRB030329)
obtained with combined GMRT and VLA data. We report on the low frequency radio
monitoring of SN 1995N and our objectives of distinguishing between competing
models of X-ray emission from this SN and the nature of its progenitor by X-ray
spectroscopy. Radio studies on SN 2001gd, SN 2001ig and SN 2002hh are
mentioned.


title:
Gravitational Microlensing: A Tool for Detecting and Characterizing
  Free-Floating Planets

abstract:
  Various methods have been proposed to search for extrasolar planets. Compared
to the other methods, microlensing has unique applicabilities to the detections
of Earth-mass and free-floating planets. However, the microlensing method is
seriously flawed by the fact that the masses of the detected planets cannot be
uniquely determined. Recently, Gould, Gaudi, & Han introduced an observational
setup that enables one to resolve the mass degeneracy of the Earth-mass
planets. The setup requires a modest adjustment to the orbit of an already
proposed Microlensing planet-finder satellite combined with ground-based
observations. In this paper, we show that a similar observational setup can
also be used for the mass determinations of free-floating planets with masses
ranging from ~0.1 M_J to several Jupiter masses. If the proposed observational
setup is realized, the future lensing surveys will play important roles in the
studies of Earth-mass and free-floating planets, which are the populations of
planets that have not been previously probed.


title: Finite volume effects for non-Gaussian multi-field inflationary models

abstract:
  Models of multi-field inflation exhibiting primordial non-Gaussianity have
recently been introduced. This is the case in particular if the fluctuations of
a light field scalar field, transverse to the inflaton direction, with quartic
coupling can be transferred to the metric fluctuations. So far in those
calculations only the ensemble statistical properties have been considered. We
explore here how finite volume effects could affect those properties. We show
that the expected non-Gaussian properties survive at a similar level when the
finite volume effects are taken into account and also find that they can skew
the metric distribution even though the ensemble distribution is symmetric.


title:
High order correlation functions for self interacting scalar field in de
  Sitter space

abstract:
  We present the expressions of the three- and four-point correlation functions
of a self interacting light scalar field in a de Sitter spacetime at tree order
respectively for a cubic and a quartic potential. Exact expressions are derived
and their limiting behaviour on super-horizon scales are presented. Their
essential features are shown to be similar to those obtained in a classical
approach.


title: Clues on galaxy and cluster formation from their scaling relations

abstract:
  By means of high-resolution N-body simulations in a LambdaCDM cosmology, we
verify that scaling relations similar to those observed for nearby galaxy
clusters are also defined by their dark matter hosts; the slopes, however, are
not the same. We then show that the scaling relations of galaxy clusters can be
explained as the result of the cosmological collapse of density fluctuations at
the appropriate scales, plus a systematic trend of the M/L ratio with cluster
mass. The empirical fact that the exponent of the Faber-Jackson relation of
elliptical galaxies is significantly different (higher) than that of clusters,
force us to conclude that the galaxy scaling laws might derive from the
cosmological collapse of density fluctuations at the epoch when galactic scales
became non-linear, plus modifications afterward due to early-time dissipative
merging.


title:
Brightest cluster galaxy formation in the cluster C0037-2522: flattening
  of the dark matter cusp

abstract:
  The X-ray cluster C0337-2522 at redshift $z=0.59$ hosts in its core a group
of five elliptical galaxies. Using N-body simulations we show that a multiple
merging event among the five galaxies is expected to take place in the next few
Gyrs, forming a central brightest cluster galaxy. We also find indications that
dynamical friction heating associated with this event is likely to modify the
central slope of the cluster dark matter density profile.


title: X-ray and radio prompt emission from a hypernova SN 2002ap

abstract:
  Here we report on combined X-ray and radio observations of SN 2002ap with
XMM-Newton ToO observation and GMRT observations aided with VLA published
results. In deriving the X-ray flux of SN 2002ap we account for the
contribution of a nearby source, found to be present in the pre-SN explosion
images obtained with Chandra observatory. We also derive upper limits on mass
loss rate from X-ray and radio data. We suggest that the prompt X-ray emission
is non-thermal in nature and its is due to the repeated compton boosting of
optical photons. We also compare SN's early radiospheric properties with two
other SNe at the same epoch.


title:
Does Magnetic Levitation or Suspension Define the Masses of Forming
  Stars?

abstract:
  We investigate whether magnetic tension can define the masses of forming
stars by holding up the subcritical envelope of a molecular cloud that suffers
gravitational collapse of its supercritical core. We perform an equilibrium
analysis of the initial and final states assuming perfect field freezing, no
rotation, isothermality, and a completely flattened configuration. The sheet
geometry allows us to separate the magnetic tension into a levitation
associated with the split monopole formed by the trapped flux of the central
star and a suspension associated with curved field lines that thread the static
pseudodisk and envelope of material external to the star. We find solutions
where the eigenvalue for the stellar mass is a fixed multiple of the initial
core mass of the cloud. We verify the analytically derived result by an
explicit numerical simulation of a closely related 3-D axisymmetric system.
However, with field freezing, the implied surface magnetic fields much exceed
measured values for young stars. If the pinch by the central split monopole
were to be eliminated by magnetic reconnection, then magnetic suspension alone
cannot keep the subcritical envelope (i.e., the entire model cloud) from
falling onto the star. We argue that this answer has general validity, even if
the initial state lacked any kind of symmetry, possessed rotation, and had a
substantial level of turbulence. These findings strongly support a picture for
the halt of infall that invokes dynamic levitation by YSO winds and jets, but
the breakdown of ideal magnetohydrodynamics is required to allow the appearance
in the problem of a rapidly rotating, centrifugally supported disk. We use
these results to calculate the initial mass function and star formation
efficiency for the distributed and clustered modes of star formation.


title:
Detection of Molecular Clouds in the Interarm of the Flocculent Galaxy
  NGC 5055

abstract:
  We present high-resolution (~ 4") 12CO (J = 1 - 0) mapping observations with
high - velocity resolution (~ 2.6 km s^{-1}) toward the disk of flocculent
galaxy NGC 5055, using the Nobeyama Millimeter Array in order to study the
physical properties of the molecular clouds in the arm and the interarm. The
obtained map shows clumpy structures. Although these are mainly distributed
along a spiral arm seen in near-infrared observations, some clouds are located
far from the arm, namely in the interarm. These clouds in both the arm and the
interarm have a typical size and mass of a few 100 pc and a few 10^6 Mo,
respectively. These correspond to the largest Giant Molecular Cloud (GMC) in
our Galaxy, and are slightly smaller than Giant Molecular Associations (GMAs)
in the grand design spiral M 51. Their CO flux-based masses show good agreement
with their virial masses. A size - velocity dispersion relation is also plotted
on an extension of the relation for the Galactic GMCs. These facts suggest that
the properties of these clouds are similar to that of the Galactic GMCs. We
also found no clear systematic offset between the molecular gas and HII regions
unlike M 51. This fact and no existense of GMAs suggest the view that, in NGC
5055, cloud formation and following star formation in both the arm and the
interarm are due to enhancement of gas by local fluctuation. On the other hand,
in grand design spiral galaxies, such as M 51, GMA formations may occur only in
the arm due to a strong density wave also enhanced star formation in GMA
formation may also occur. These may control the optical morphology of spiral
arms in spiral galaxies.


title: The relation between galactic properties and cluster structure

abstract:
  A satisfactory understanding of the origin of the dependence of galaxy
properties on their environment has remained, so far, out of reach. In the
light of numerous observational results and substantial theoretical progress
obtained for clusters of galaxies in the last years, a primary goal is to
understand how the star formation activity depends on cluster substructure,
i.e. on the merging/accretion history of a cluster. In this contribution we
present a case in which it is possible to identify the cluster environment, and
in particular the intracluster medium and the recent infall history of galaxies
onto the cluster, as the cause for an abrupt change in the star formation
histories of a subset of galaxies in the Coma cluster.


title: Stellar Populations, Butcher-Oemler Effect, Star Formation in Clusters

abstract:
  In this brief overview of the stellar populations of galaxies in clusters I
highlight some of the most recent results, including the downsizing of the k+a
population and the star formation--local density relation. I conclude
discussing some open questions regarding the interpretation of the
observational results, and speculating on the current meaning of the words
``primordial'' and ``environmental''.


title:
The Virgo Alignment Puzzle in Propagation of Radiation on Cosmological
  Scales

abstract:
  We reconsider analysis of data on the cosmic microwave background on the
largest angular scales. Temperature multipoles of any order factor naturally
into a direct product of axial quantities and cosets. Striking coincidences
exist among the axes associated with the dipole, quadrupole, and octupole CMB
moments. These axes also coincide well with two other axes independently
determined from polarizations at radio and optical frequencies propagating on
cosmological scales. The five coincident axes indicate physical correlation and
anisotropic properties of the cosmic medium not predicted by the conventional
Big Bang scenario. We consider various mechanisms, including foreground
corrections, as candidates for the observed correlations. We also consider
whether the propagation anomalies may be a signal of ``dark energy'' in the
form of a condensed background field. Perhaps {\it light propagation} will
prove to be an effective way to look for the effects of {\it dark energy}.


title:
Non-Gaussian Signatures in the Lens Deformations of the CMB Sky. A New
  Ray-Tracing Procedure

abstract:
  We work in the framework of an inflationary cold dark matter universe with
cosmological constant, in which the cosmological inhomogeneities are considered
as gravitational lenses for the CMB photons. This lensing deforms the angular
distribution of the CMB maps in such a way that the induced deformations are
not Gaussian. Our main goal is the estimation of the deviations with respect to
Gaussianity appeared in the distribution of deformations. In the new approach
used in this paper, matter is evolved with a particle-mesh N-body code and,
then, an useful ray-tracing technique designed to calculate the correlations of
the lens deformations induced by nonlinear structures is applied. Our approach
is described in detail and tested. Various correlations are estimated at an
appropriate angular scale. The resulting values point out both deviations with
respect to Gaussian statistics and a low level of correlation in the lens
deformations.


title:
Anisotropy in the distribution of satellites around primary galaxies in
  the 2dFGRS: the Holmberg effect

abstract:
  We have analysed a sample of satellite and primary galaxies in the 2dF galaxy
redshift survey. In our study we find a strong statistical evidence of the
Holmberg effect (that is a tendency for satellites to avoid regions along the
line defined by the primary plane) within 500 kpc of projected distance to the
primary. This effect is present only when we restrict to objects with radial
velocity relative to the primary $|\Delta v|<160$ km/s which correspond
approximately to the mean of the distribution. We explore the dependence of
this anisotropy on spectral type ($\eta$), colours, and luminosities of both
primaries and satellites, finding that objects with a low present-day star
formation rate present the most significant effect.


title:
Dynamical effects of interactions and the Tully-Fisher relation for
  Hickson compact groups

abstract:
  We investigate the properties of the B-band Tully-Fisher (T-F) relation for
25 compact group galaxies, using Vmax derived from 2-D velocity maps. Our main
result is that the majority of the Hickson Compact Group galaxies lie on the
T-F relation. However, about 20% of the galaxies, including the lowest-mass
systems, have higher B luminosities for a given mass, or alternatively, a mass
which is too low for their luminosities. We favour a scenario in which outliers
have been brightened due to either enhanced star formation or merging.
Alternatively, the T-F outliers may have undergone truncation of their dark
halo due to interactions. It is possible that in some cases, both effects
contribute. The fact that the B-band T-F relation is similar for compact group
and field galaxies tells us that these galaxies show common mass-to-size
relations and that the halos of compact group galaxies have not been
significantly stripped inside R25. We find that 75% of the compact group
galaxies studied (22 out of 29) have highly peculiar velocity fields.
Nevertheless, a careful choice of inclination, position angle and center,
obtained from the velocity field, and an average of the velocities over a large
sector of the galaxy enabled the determination of fairly well-behaved rotation
curves for the galaxies. However, two of the compact group galaxies which are
the most massive members in M51--like pairs, HCG 91a and HCG 96a, have very
asymmetric rotation curves, with one arm rising and the other one falling,
indicating, most probably, a recent perturbation by the small close companions.


title:
Chandra ACIS and Newton EPIC Observations of the X-ray Luminous SN1978K
  in NGC 1313

abstract:
  We describe an observation of the X-ray luminous SN1978K in NGC 1313 using
the ACIS detector on Chandra and an archival Newton EPIC observation. The
models that provided good fits to the ASCA SIS and GIS and the ROSAT PSPC
spectra no longer do so for the ACIS or EPIC spectra. The best-fit model to the
ACIS and EPIC spectra are dual hot plasma model (vmekal); one component is soft
(T = 0.61+0.04-0.05 keV, 90% errors) and the other is harder (T=3.16+0.44-0.40
keV). For the varying abundances permitted within the model, only the Si
abundance of the soft component differs from solar, with a value
n(Si)(SN78K)/n(Si)(solar) = 3.20+1.80-1.90 (90% errors). From a ratio of the
low- and high-T model fits to the Chandra and XMM-Newton spectra, we infer an
exponent n of the ejecta density distribution, rho_ejecta ~ r^(-n), of ~5.2,
adopting a circumstellar matter distribution exponent of s = 2 (rho_cs ~
r^(-s)). The 0.5-2 keV light curve shows essentially no decline; the 2-10 keV
light curve, constructed only of the ASCA, XMM-Newton, and Chandra
observations, shows a drop of 1.5 from the ASCA epoch. The hard band decline,
together with the apparently enhanced Si emission, signal the start of the
X-ray decline of SN1978K.


title: Open Problems in Cosmology

abstract:
  The main task for cosmology today is the completion of the program of
cosmological tests that commenced in the 1930s. I offer comments on the state
of the program and the issues to be addressed to establish a convincing
large-scale picture of the observable universe.


title: Quasar Atmospheres: Toward a "Low" Theory for Quasars

abstract:
  After 40 years we have no "low" theory of quasars to predict the atomic
absorption and emission features so abundant in quasar spectra. Here I take the
first step, using results selected for their diagnostic power to build an
"observational paradigm" unifying all the atomic features in quasars. This
paradigm bears a remarkable resemblance to the one I proposed in Elvis (2000,
astro-ph/0008064)! Yet all the results used here were not used in that earlier
study, with one exception. The Elvis (2000) model has been tested by the new
data and has survived, and so has been strengthened. The structure is readily
tested, is physically suggestive, and opens up many areas for detailed
modelling. From this I believe a truly predictive "low" theory of quasars will
emerge.


title: Optical CCD Observations of Eta Carinae at La Plata Observatory

abstract:
  In 2003.5 Eta Carinae was expected to undergo an X-ray eclipse (Damineli et
al., 2000). In the framework of an international campaign to obtain
multi-wavelength observations of this event, we have obtained optical CCD
images of Eta Carinae. Here, we present the B, V, R, I, data of Eta Car
obtained before and during the X-ray eclipse.


title: Photon Pickup by Intense Poynting Flows

abstract:
  It is suggested that a Poynting flux-dominated outflow with a sufficiently
strong magnetic field can pick up hard X-ray photons when the magnetic field is
of sufficient strength. The zeroth generation X-rays pair produce, and the
pairs radiate extremely energetic first generation photons that could be
detected by extensive air shower arrays and/or MILAGRO if they escape the
production site intact. Giant flares from magnetars may thus yield bursts of
UHE photons. GRB-associated Poynting flows may be unstable to pair production
near their source, and their energy rapidly converted to pairs.


title:
Optical and Infrared Photometry of the Nearby Type Ia Supernovae 1999ee,
  2000bh, 2000ca, and 2001ba

abstract:
  We present near infrared photometry of the Type Ia supernova 1999ee; also,
optical and infrared photometry of the Type Ia SNe 2000bh, 2000ca, and 2001ba.
For SNe 1999ee and 2000bh we present the first-ever SN photometry at 1.035
microns (the Y-band). We present K-corrections which transform the infrared
photometry in the observer's frame to the supernova rest frame. Using our
infrared K-corrections and stretch factors derived from optical photometry, we
construct JHK templates which can be used to determine the apparent magnitudes
at maximum if one has some data in the window -12 to +10 d with respect to
T(B_max). Following up previous work on the uniformity of V minus IR loci of
Type Ia supernovae of mid-range decline rates, we present unreddened loci for
slow decliners. We also discuss evidence for a continuous change of color at a
given epoch as a function of decline rate.


title: Fast accretion of small planetesimals by protoplanetary cores

abstract:
  We explore the dynamics of small planetesimals coexisting with massive
protoplanetary cores in a gaseous nebula. Gas drag strongly affects the motion
of small bodies leading to the decay of their eccentricities and inclinations,
which are excited by the gravity of protoplanetary cores. Drag acting on larger
($\gtrsim 1$ km), high velocity planetesimals causes a mere reduction of their
average random velocity. By contrast, drag qualitatively changes the dynamics
of smaller ($\lesssim 0.1-1$ km), low velocity objects: (1) small planetesimals
sediment towards the midplane of the nebula forming vertically thin subdisk;
(2) their random velocities rapidly decay between successive passages of the
cores and, as a result, encounters with cores typically occur at the minimum
relative velocity allowed by the shear in the disk. This leads to a drastic
increase in the accretion rate of small planetesimals by the protoplanetary
cores, allowing cores to grow faster than expected in the simple oligarchic
picture, provided that the population of small planetesimals contains more than
roughly 1% of the solid mass in the nebula. Fragmentation of larger
planetesimals ($\gtrsim 1$ km) in energetic collisions triggered by the
gravitational scattering by cores can easily channel this amount of material
into small bodies on reasonable timescales ($< 1$ Myr in the outer Solar
System), providing a means for the rapid growth (within several Myr at 30 AU)
of rather massive protoplanetary cores. Effects of inelastic collisions between
planetesimals and presence of multiple protoplanetary cores are discussed.


title: Single pulses from PSR B1641-45

abstract:
  The integrated profile of PSR B1641-45 can be decomposed into four Gaussian
components. The sum of these Gaussian components can be made to replicate the
total intensity, linear and circular polarization of the integrated profile,
and the discontinuity in the swing of the position angle. Surprisingly, the
single pulses from PSR B1641-45 can also be decomposed into these same Gaussian
components with only the amplitude of the components as a free parameter. The
distributions of the fitted amplitudes are log-normal. Under the assumption
that emission consists of 100% polarized orthogonal modes which are emitted
simultaneously, I show that the polarization properties of the single pulses
can also be replicated in a simple way. This lends support to models involving
the superposition of orthogonal modes rather than disjoint emission of the
modes.


title:
Simulation of Ultra-High Energy Photon Propagation in the Geomagnetic
  Field

abstract:
  The identification of primary photons or specifying stringent limits on the
photon flux is of major importance for understanding the origin of ultra-high
energy (UHE) cosmic rays. We present a new Monte Carlo program allowing
detailed studies of conversion and cascading of UHE photons in the geomagnetic
field. The program named PRESHOWER can be used both as an independent tool or
together with a shower simulation code. With the stand-alone version of the
code it is possible to investigate various properties of the particle cascade
induced by UHE photons interacting in the Earth's magnetic field before
entering the Earth's atmosphere. Combining this program with an extensive air
shower simulation code such as CORSIKA offers the possibility of investigating
signatures of photon-initiated showers. In particular, features can be studied
that help to discern such showers from the ones induced by hadrons. As an
illustration, calculations for the conditions of the southern part of the
Pierre Auger Observatory are presented.


title:
CCD Photometric Observations of the Galactic Globular Clusters NGC 1904
  and NGC 6341

abstract:
  We present multi-colour broad band CCD photometric observations of a few
thousands of stars located region of the galactic globular clusters NGC 1904
and NGC 6341. These observations are used to generate their deep colour
magnitude diagrams (CMDs) to study overall morphologies of sub giant, red
giant, asymptotic giant and horizontal branches. We also determine the main
sequence morphology of the NGC 6341. A comparison of their CMDs with the
theoretical isochrones given by Demarque et al. (1996) indicates an age of 14
and 16 Gyr for NGC 1904 and NGC 6341 GGCs respectively. We present a new method
for artificial add star experiment. Using this method on the photometric data
of galactic globular cluster NGC 6341, we determined the completeness factor in
B, V and I pass bands. We have determined the luminosity function of the main
sequence stars down to V $\sim$ 21.0 (M$_{V} \sim$ 6.5) from the V Vs (B-V)
colour magnitude diagram of this cluster. Using accurate parameters of 64 GGCs,
we derived relations between galactocentric distance R, distance from the
galactic plane Z$_{g}$ and metalicity [Fe/H] of GGCs.


title:
Extended self-similarity of the small-scale cosmic microwave background
  anisotropy

abstract:
  The Extended Self-Similarity (ESS) of cosmic microwave background (CMB)
radiation has been studied using recent data obtained by the space-craft based
Wilkinson Microwave Anisotropy Probe. Using the ESS and the high angular scale
resolution (arcminutes) of the data it is shown that the CMB temperature space
{\it increments} exhibit considerable and systematic declination from
Gaussianity for high order moments at the small angular scales. Moreover, the
CMB space increment ESS exponents have remarkably close values to the ESS
exponents observed in turbulence (in magnetohydrodynamic turbulence).


title: Multiscale self-organized criticality and powerful X-ray flares

abstract:
  A combination of spectral and moments analysis of the continuous X-ray flux
data is used to show consistency of statistical properties of the powerful
solar flares with 2D BTW prototype model of self-organized criticality.


title: Rapid N_H Changes in NGC 4151

abstract:
  We have analyzed two long BeppoSAX observations of the bright Seyfert galaxy
NGC 4151, searching for short timescale (10-200 ksec) X-ray spectral
variability. The light curve of a softness ratio, chosen as most sensitive to
pinpoint changes of the column density of the absorbing gas along the line of
sight, shows significant variations. We try to model these variations by
performing a detailed, time resolved, spectral analysis. We find significant,
large (factors of 1.5-6) variations of the absorber column densities on time
scales of 40-200 ksec. These values are 10-100 times shorter than those found
by Risaliti et al. 2002 in a sample of Seyfert 2 galaxies, and provide strong
constraints on the geometry of the obscuring medium.


title: The Infrared Continuum of Active Galaxies

abstract:
  We discuss the different physical processes contributing to the infrared
continuum of AGN, assuming that both photoionization from the active center and
shocks ionize and heat the gas and dust contained in an ensemble of clouds
surrounding the nucleus. Radiation transfer of primary and secondary radiation
throughout a cloud is calculated consistently with collisional processes due to
the shock. We consider that the observed continuum corresponds to reprocessed
radiation from both dust and gas in the clouds. The model is applied to the
continuum of Seyfert galaxies from which best estimate of the nuclear, stellar
subtracted, emission is available. The results show that radiation-dominated
high velocity clouds are more numerous in Seyfert 1-1.5 whereas shock-dominated
low velocity clouds are dominant in Seyfert type 2 in full agreement with the
unified model for AGN. In type 2 objects, radiation is partly suppressed by a
central dusty medium with a high dust-to-gas ratio. A grid of models is used to
provide a phenomenological analysis of the observed infrared spectral energy
distribution.


title: A comment on 'Accurate spin axes and solar system dynamics'

abstract:
  In a recent paper, Edvardsson etal (2002) propose a new solution for the spin
evolution of the Earth and Mars. Their results differ significantly with
respect to previous studies, as they found a large contribution on the
precession of the planet axis from the tidal effects of Phobos and Deimos. In
fact, this probably results from the omission by the authors of the torques
exerted on the satellites orbits by the planet's equatorial bulge, as otherwise
the average torque exerted by the satellites on the planet is null.


title: Another Decade of Strange Quark Matter (ASTRO) Physics

abstract:
  We present a perspective of strange quark matter research in the 1991-2001
decade focused on astrophysics topics, with particular attention to open
problems. We outline the basic concepts and developments in the field, paying
attention to the established research and promising perspectives. An analysis
of the whole literature (experimental searches, theory,
astrophysical/cosmological) serves to point out some general trends, supported
by a fairy complete statistical sample of published works.


title:
On the Influence of Uncertainties in Chemical Reaction Rates on Results
  of the Astrochemical Modelling

abstract:
  With the chemical reaction rate database UMIST95 (Millar et al. 1997) we
analyze how uncertainties in rate constants of gas-phase chemical reactions
influence the modelling of molecular abundances in the interstellar medium.
Random variations are introduced into the rate constants to estimate the
scatter in theoretical abundances. Calculations are performed for dark and
translucent molecular clouds where gas phase chemistry is adequate. Similar
approach was used by Pineau des Forets & Roueff (2000) for the study of
chemical bistability. All the species are divided into 6 sensitivity groups
according to the value of the scatter in their model abundances computed with
varied rate constants. It is shown that the distribution of species within
these groups depends on the number of atoms in a molecule and on the adopted
physical conditions. The simple method is suggested which allows to single out
reactions that are most important for the evolution of a given species.


title: X-ray Cluster Large Scale Structure and Cosmology

abstract:
  We outline main arguments in favor of cosmological X-ray surveys of galaxy
clusters. We summarize recent advances in our understanding of cluster physics.
After a short review of past surveys, we present the scientific motivations of
the XMM Large Scale Structure survey. We further illustrate how such a survey
can help constrain the nature of the dark energy as well as cluster scaling law
evolution, i.e. non gravitational physics.


title: A transient large-scale relativistic radio jet from GX 339-4

abstract:
  We report on the formation and evolution of a large-scale,
synchrotron-emitting jet from the black hole candidate and X-ray binary system
GX 339-4. In 2002 May, the source moved from a low/hard to a very high X-ray
state, contemporaneously exhibiting a very bright optically thin radio flare.
Further observations with the Australia Telescope Compact Array have tracked
the formation of a collimated structure extending to about 12 arcsec, with
apparent velocity greater than 0.9c. The luminosity of the outflow seems to be
rapidly decreasing; these observations confirm that transient large-scale jets
are likely to be common events triggered by X-ray state transitions in black
hole X-ray binaries.


title:
SAX J1808.4-3658 and the origin of X-ray variability in X-ray binaries
  and active galactic nuclei

abstract:
  The aperiodic X-ray variability in neutron star and black hole X-ray binaries
(XRBs), and active galactic nuclei (AGN) shows a characteristic linear
relationship between rms amplitude and flux, implying a multiplying-together or
`coupling' of variability on different time-scales. Such a coupling may result
from avalanches of flares, due to magnetic reconnection in an X-ray emitting
corona. Alternatively this coupling may arise directly from the coupling of
perturbations in the accretion flow, which propagate to the inner emitting
regions and so modulate the X-ray emission. Here, we demonstrate explicitly
that the component of aperiodic variability which carries the rms-flux relation
in the accreting millisecond pulsar SAX J1808.4-3658 is also coupled to the 401
Hz pulsation in this source. This result implies that the rms-flux relation in
SAX J1808.4-3658 is produced in the accretion flow on to the magnetic caps of
the neutron star, and not in a corona. By extension we infer that propagating
perturbations in the accretion flow, and not coronal flares, are the source of
the rms-flux relations and hence the aperiodic variability in other XRBs and
AGN.


title: Quasar Winds as Dust Factories at High Redshift

abstract:
  Winds from AGN and quasars will form large amounts of dust, as the cool gas
in these winds passes through the (pressure, temperature) region where dust is
formed in AGB stars. Conditions in the gas are benign to dust at these radii.
As a result quasar winds may be a major source of dust at high redshifts,
obviating a difficulty with current observations, and requiring far less dust
to exist at early epochs.


title: Zero-Field Dichroism in the Solar Chromosphere

abstract:
  We explain the linear polarization of the Ca II infrared triplet observed
close to the edge of the solar disk. In particular, we demonstrate that the
physical origin of the enigmatic polarizations of the 866.2 nm and 854.2 nm
lines lies in the existence of atomic polarization in their metastable lower
levels, which produces differential absorption of polarization components
(dichroism). To this end, we have solved the problem of the generation and
transfer of polarized radiation by taking fully into account all the relevant
optical pumping mechanisms in multilevel atomic models. We argue that
`zero-field' dichroism may be of great diagnostic value in astrophysics.


title:
A survey of SiO 5-4 emission towards outflows from low-luminosity
  protostellar candidates

abstract:
  We have observed the SiO J=5--4 line towards a sample of 25 low-luminosity
(L* < 10^3 Lsun) protostellar outflow systems. The line was detected towards 7
of the 25 sources, a detection rate of 28 per cent. The majority (5 out of 7)
of sources detected were of class 0 status. We detected a higher fraction of
class 0 sources compared with the class I and II sources, although given the
small numbers involved the significance of this result should be regarded as
tentative. Most of the detected sources showed emission either at or close to
the central position, coincident with the protostar. In four cases (HH211,
HH25MMS, V-380 OriNE and HH212) emission was also detected at positions away
from the center, and was stronger than that observed at the centre position.
  SiO abundances of 10^(-8) to 8x10^(-7) are derived from LTE analysis. For 2
sources we have additional transitions which we use to conduct statistical
equilibrium modeling to estimate the gas density in the SiO-emitting regions.
For HH25MMS these results suggest that the SiO emission arises in a
higher-density region than the methanol previously observed. We find that the
most likely explanation for the preferential detection of SiO emission towards
class 0 sources is the greater density of those environments, reinforced by
higher shock velocities. We conclude that while not all class 0 sources exhibit
SiO emission, SiO emission is a good signpost for the presence of class 0
sources.


title: Massive Black Holes in Dwarf Spheroidal Galaxy Haloes?

abstract:
  It is now established that several of the Local Group dwarf Spheroidal
galaxies (dSphs) have large mass-to-light ratios. We consider the possibility
that the dark matter in the halos of dSphs is composed of massive black holes
with masses in the range 10^5 to 10^7 solar masses. We use direct N-body
simulations to determine the long term evolution of a two-component dSph
composed of a pressure-supported stellar population in a black hole halo. The
black holes are initially distributed according to a Navarro, Frenk & White
profile. For black hole masses between 10^5 and 10^6 solar masses, the dark
matter halo evolves towards a shallower inner profile in less than a Hubble
time. This suggests that black holes in this mass range might provide an
explanation for the origin of the dark matter cores inferred from observations
of Low Surface Brightness galaxy rotation curves. We compare the simulated
evolution of the stellar population with observed data for the Draco dSph. The
dependence of the heating rate on the black hole mass is determined, and an
upper limit of 10^5 solar masses is placed on the individual black holes
comprising the dark matter halo of Draco, if its present stellar distribution
is representative of the initial one. We also present a simple scaling argument
which demonstrates that the dynamical heating of an initially compact, though
not self-gravitating, stellar distribution might produce a remnant distribution
similar in extent to Draco after 10 Gyr, even for black hole masses somewhat in
excess of 10^5 solar masses.


title: Empirically Constrained Color-Temperature Relations. II. uvby

abstract:
  (Abriged) A new grid of theoretical color indices for the Stromgren uvby
photometric system has been derived from MARCS model atmospheres and SSG
synthetic spectra for cool dwarf and giant stars. At warmer temperatures this
grid has been supplemented with the synthetic uvby colors from recent Kurucz
atmospheric models without overshooting. Our transformations appear to
reproduce the observed colors of extremely metal-poor turnoff and giant stars
(i.e., [Fe/H]<-2). Due to a number of assumptions made in the synthetic color
calculations, however, our color-temperature relations for cool stars fail to
provide a suitable match to the uvby photometry of both cluster and field stars
having [Fe/H]>-2. To overcome this problem, the theoretical indices at
intermediate and high metallicities have been corrected using a set of color
calibrations based on field stars having accurate IRFM temperature estimates
and spectroscopic [Fe/H] values. Encouragingly, isochrones that employ the
transformations derived in this study are able to reproduce the observed CMDs
(involving u-v, v-b, and b-y colors) for a number of open and globular clusters
(including M92, M67, the Hyades, and 47Tuc) rather well. Moreover, our
interpretations of such data are very similar, if not identical, with those
given by VandenBerg & Clem (2003, AJ, 126, 778) from a consideration of BV(RI)c
observations for the same clusters. In the present investigation, we have also
analyzed the observed Stromgren photometry for the classic Population II
subdwarfs, compared our "final" (b-y)-Teff relationship with those derived
empirically in a number of recent studies, and examined in some detail the
dependence of the m1 index on [Fe/H].


title: Galaxy formation in pre-processed dark halos

abstract:
  Recent N-body simulations show that the formation of a present-day, galaxy
sized dark matter halo in the CDM cosmogony in general consists of an early
fast collapse phase, during which the potential associated with a halo is
established, followed by a slow accretion phase, during which mass is added
rather gently in the outer region. Here we outline a scenario in which the fast
collapse phase is accompanied with rapid formation of cold clouds and with
starbursts that can eject a large amount of gas from the halo center.The loss
of orbital energy of the cold clouds to the dark matter and the ejection of gas
from halo center by starburst can significantly reduce the halo concentration.
The outflow from the starburst can also heat the gas in the protogalaxy region.
Subsequent formation of galaxies in the slow accretion regime is therefore in
halos that have been pre-processed by these processes and may have properties
different from that given by N-body simulations.
  This scenario can help to solve several outstanding problems in the standard
  Lambda CDM model of galaxy formation without compromising its success in
allowing structure formation at high redshift. The predicted rotation curves
are quite flat,alleviating the discrepancy of the Tully-Fisher relation
predicted in the Lambda CDM model with observations. The flattened galaxy halos
allow accreted minihalos to survive in their central regions longer, which may
be helpful in producing the flux anomalies observed in some gravitational
lensing systems. The preheating by the early starbursts effectively reduces the
amount of gas that can be accreted into galaxy halos, which may explain why the
baryon fraction in a spiral galaxy is in general much lower than the universal
baryon fraction, f_B~0.16, in the standard Lambda CDM model.


title:
Characteristics of Diffuse X-Ray Line Emission within 20 pc of the
  Galactic Center

abstract:
  Over the last 3 yrs, the Galactic center (GC) region has been monitored with
the Chandra X-Ray Observatory. With 11 Chandra observations through 2002 June,
the total effective exposure reaches ~590 ks, providing significant photon
statistics on the faint, filamentary, diffuse X-ray emission. The true-color
X-ray image and the equivalent width (EW) images for the detected elemental
species demonstrate that the diffuse X-ray features have a broad range of
spatio-spectral properties. Enhancements of the low-ionization-state, or
``neutral'' Fe line emission (E~6.4 keV) to the northeast of Sgr A* can be
interpreted as fluorescence within the dense ISM resulting from irradiation by
hard, external X-ray sources. They may also be explained by emission induced by
the bombardments by high energy particles on the ISM, such as unresolved
supernova (SN) ejecta intruding into dense ISM. The detection of molecular
cloud counterparts to the 6.4 keV Fe line features indicates that these Fe line
features are associated with dense GC clouds and/or active star-forming
regions, which supports the X-ray reflection and/or SN ejecta origins for the
Fe line emission. We detect highly ionized S and Si lines which are generally
coincident with the neutral Fe line emission and the dense molecular clouds in
the northeast of Sgr A*. These hot plasmas are likely produced by massive
star-forming activities and/or SNRs. In contrast, we find that highly ionized
He-like Fe line emission (E~6.7 keV) is primarily distributed along the plane
instead of being concentrated in the northeast of Sgr A*. The implied high
temperature and the alignment along the plane are consistent with the magnetic
confinement model.


title:
Modification of Projected Velocity Power Spectra by Density
  Inhomogeneities in Compressible Supersonic Turbulence

abstract:
  (Modified) The scaling of velocity fluctuation, dv, as a function of spatial
scale L in molecular clouds can be measured from size-linewidth relations,
principal component analysis, or line centroid variation. Differing values of
the power law index of the scaling relation dv = L^(g3D) in 3D are given by
these different methods: the first two give g3D=0.5, while line centroid
analysis gives g3D=0. This discrepancy has previously not been fully
appreciated, as the variation of projected velocity line centroid fluctuations
(dv_{lc} = L^(g2D)) is indeed described, in 2D, by g2D=0.5. However, if
projection smoothing is accounted for, this implies that g3D=0. We suggest that
a resolution of this discrepancy can be achieved by accounting for the effect
of density inhomogeneity on the observed g2D obtained from velocity line
centroid analysis. Numerical simulations of compressible turbulence are used to
show that the effect of density inhomogeneity statistically reverses the effect
of projection smoothing in the case of driven turbulence so that velocity line
centroid analysis does indeed predict that g2D=g3D=0.5. Using our numerical
results we can restore consistency between line centroid analysis, principal
component analysis and size-linewidth relations, and we derive g3D=0.5,
corresponding to shock-dominated (Burgers) turbulence. We find that this
consistency requires that molecular clouds are continually driven on large
scales or are only recently formed.


title:
The Response of a Two-Element Radio Interferometer to Gravitational
  Waves

abstract:
  This document presents a ray-optics analysis of the response of a two-element
radio interferometer to the presence of a plane gravitational wave. A general
expression for the differential phase observed between the two receiving
stations as a result of an arbitrary gravitational wave is determined, as well
as the specific responses to monochromatic and black hole ring-down waveforms.
Finally, the possibility of gravitational wave detection via this mechanism is
discussed in the context of interferometer noise.


title: Formation rates of core collapse SNe and GRBs

abstract:
  We study the evolution of stars that may be the progenitors of long-soft
gamma-ray burst (GRBs) -- rotating naked helium stars presumed to have lost
their envelopes to winds or companions. Our aim is to investigate the formation
and development of single and binary systems and from this population evaluate
the rates of interesting individual species. Using a rapid binary evolution
algorithm, that enables us to model the most complex binary systems and to
explore the effect of metallicity on GRB production, we draw the following
conclusions. First we find that, if we include an approximate treatment of
angular momentum transport by mass loss, the resulting spin rates for single
stars become too low to form a centrifugally supported disc that can drive a
GRB engine. Second massive stars in binaries result in enough angular momentum
-- due to spin-orbit tidal interactions -- to form a centrifugally supported
disc and are thus capable of supplying a sufficient number of progenitors. This
holds true even if only a small fraction of bursts are visible to a given
observer and the GRB rate is several hundred times larger than the observed
rate. Third low-metallicity stars aid the formation of a rapidly rotating,
massive helium cores at collapse and so their evolution is likely to be
affected by the local properties of the ISM. This effect could increase the GRB
formation rate by a factor of 5-7 at Z=Z_solar/200. Finally we quantify the
effects of mass loss, common-envelope evolution and black-hole formation and
show that more stringent constraints to many of these evolution parameters are
needed in order to draw quantitative conclusions from population synthesis
work.


title: On Mach's critique of Newton and Copernicus

abstract:
  Maintaining the relativity of all motion, especially rotational motion, Mach
denied the existence of absolute motion and absolute space. He maintained the
equivalence of the Ptolemaic and the Copernican systems and the equivalence of
a fixed bucket in a rotating universe with the converse. An analysis of the
Foucault pendulum shows that there cannot be a fixed bucket in a rotating
universe. Also, Mach's views violate the physics he espoused: non-inertial
experiments, e.g. stellar aberration and electromagnetic effects, distinguish
between a rotating bucket in a fixed universe and the converse, between the
Copernican and the Ptolemaic systems, and establish that one cannot ascribe all
observations solely to relative motion between a system and the universe.


title: Intergalactic HII Regions Discovered in SINGG

abstract:
  A number of very small isolated HII regions have been discovered at projected
distances up to 30 kpc from their nearest galaxy. These HII regions appear as
tiny emission line objects in narrow band images obtained by the NOAO Survey
for Ionization in Neutral Gas Galaxies (SINGG). We present spectroscopic
confirmation of four isolated HII regions in two systems, both systems have
tidal HI features. The results are consistent with stars forming in interactive
debris due to cloud-cloud collisions. The H-alpha luminosities of the isolated
HII regions are equivalent to the ionizing flux of only a few O stars each.
They are most likely ionized by stars formed in situ, and represent atypical
star formation in the low density environment of the outer parts of galaxies. A
small but finite intergalactic star formation rate will enrich and ionize the
surrounding medium. In one system, NGC 1533, we calculate a star formation rate
of 1.5e-3 msun/yr, resulting in a metal enrichment of ~1e-3 solar for the
continuous formation of stars. Such systems may have been more common in the
past and a similar enrichment level is measured for the `metallicity floor' in
damped Lyman-alpha absorption systems.


title: Ultra High Energy Cosmic Rays

abstract:
  Cosmic rays with energies above $10^{18}$ eV are currently of considerable
interest in astrophysics and are to be further studied in a number of projects
which are either currently under construction or the subject of well-developed
proposals. This paper aims to discuss some of the physics of such particles in
terms of current knowledge and information from particle astrophysics at other
energies.


title: A Model for 'Double Notches' in Radio Pulsar Profiles

abstract:
  Aberration and retardation of the radiation within a pulsar's magnetosphere
enable a single corotating absorbing region in the outer magnetosphere to give
rise to a 'double notch' in the pulsar's observed radio profile. This effect
requires that a pulsar has not only absorbing but also emitting regions at
heights which are a substantial proportion of the light cylinder radius. The
known presence of double notches in the weak secondary emission of three nearby
pulsars suggests that this emission comes from open field lines well above
their poles and that an obscuring region extending over no more than 5 percent
of the light cylinder radius is located at or near the light cylinder.


title: HST and VLT observations of Pulsars and their Environments

abstract:
  The state of the art of optical studies of Isolated Neutron Stars (INSs) and
their Pulsar Wind Nebulae (PWNe) is reviewed. In addition, results obtained
from recent HST and VLT observations are presented and discussed.


title: On the Feasibility of Disk Chemical Modeling

abstract:
  In this paper, we compare the results of the modeling of a protoplanetary
disk chemical evolution obtained with the UMIST95 and ``New Standard Model''
(NSM) chemical databases. Assuming the same initial conditions, it is found
that the substitution of one chemical network by another causes almost no
difference for the disk ionization degree. In contrast, the NSM and UMIST95
abundances of CO can differ by a factor of a hundred at some regions of the
disk surface. However, relevant CO vertical column densities differ much less,
at most by a factor of a few. In addition, we synthesize the single-dish
CO(J=3-2) line by means of the 2D line radiative transfer for both considered
chemical networks. It is shown that the intensity of this line in the case of
the UMIST95 abundances is lower compared to the NSM case by about 15%.


title:
Hyperon softening of the EOS of dense matter and the spin evolution of
  isolated neutron stars

abstract:
  The effect of the hyperon softening of the equation of state (EOS) of dense
matter on the spin evolution of isolated neutron stars is studied for a broad
set of hyperonic EOSs. We use a multidomain 2-D code based on a spectral
method, and show how important the precision of solving the equations of
stationary motion is for the stability analysis. For some EOSs, the hyperon
softening leads to spin-up by the angular momentum loss, in the form of the
back bending phenomenon, for a rather broad range of stellar baryon mass. We
show that large segments of the evolutionary tracks exhibiting the back bending
behaviour in the moment-of-inertia - rotation-frequency plane, are actually
unstable and therefore not astrophysically relevant. We show also that during
the spin-up - angular-momentum-loss epoch, an isolated neutron star (e.g., a
radio pulsar) can lose a sizable part of its initial angular momentum without
significantly changing its rotation period. We propose also simple arguments
and criteria allowing to connect the presence of a back bending epoch with the
mass-radius relations and the stiffness and/or softness of the nucleon and
hyperon EOSs of the neutron star core.


title: Neutrostriction in Neutron stars

abstract:
  It is demonstrated that not only gravity, but also neutrostriction forces due
to optical potential created by coherent elastic neutron-neutron scattering can
hold a neutron star together. The latter forces can be stronger than
gravitational ones. The effect of these forces on mass, radius and structure of
the neutron star is estimated.


title: The Origin of Energy for the Big Bang

abstract:
  Our universe is probably a huge black hole. If that is true, all the light
and heat ejected by various celestial bodies into the space will be confined
within it and shuttling ceaselessly, leading eventually to a uniform
equilibrium radiation at certain temperature. The authors hold that the 3 K
background radiation discovered in 1965 is actually such equilibrium radiation.
The 3 K background radiation is convincible evidence that our universe is a
closed one and it is actually a huge heat ocean.
  Billions of galaxies produced in the big bang will also be shuttling within
the closed universe, passing the central part of the universe again and again.
They have many chances to meet each other. There are numerous black holes of
various sizes in these galaxies. A black hole absorbs matter and radiation,
even swallows in other approaching celestial bodies. These black holes provide
the mechanism of matter-re-gathering and energy-re-gathering in the universe.
All the real matter will finally gather again to form a single huge black hole.
The huge black hole absorbs energy from the heat ocean further, until its
energy overpasses certain threshold value, leading to a new big bang.
  The heat ocean has energy, hence it has mass, too. Calculations show that,
the mass of the heat ocean surpasses overwhelmingly the mass of all the real
matter. The heat ocean is the dominant part of the universe, and the real
matter is only a fraction, which explodes and re-gathers repeatedly within the
universe.


title:
A long, hard look at MCG-6-30-15 with XMM-Newton II: detailed EPIC
  analysis and modelling

abstract:
  The bright Seyfert 1 galaxy MCG-6-30-15 has provided some of the best
evidence to date for the existence of supermassive black holes in active
galactic nuclei. Observations with ASCA revealed an X-ray iron line profile
shaped by strong Doppler and gravitational effects. In this paper the shape of
the iron line, its variability characteristics and the robustness of this
spectral interpretation are examined using the long XMM-Newton observation
taken in 2001. A variety of spectral models, both including and excluding the
effects of strong gravity, are compared to the data in a uniform fashion. The
results strongly favour models in which the spectrum is shaped by emission from
a relativistic accretion disc. It is far more difficult to explain the 3-10 keV
spectrum using models dominated by absorption (either by warm or partially
covering cold matter), emission line blends, curved continua or additional
continuum components. These provide a substantially worse fit to the data and
fail to explain other observations (such as the simultaneous BeppoSAX
spectrum). This reaffirms the veracity of the relativistic `disc line'
interpretation. The short term variability in the shape of the energy spectrum
is investigated and explained in terms of a two-component emission model. Using
a combination of spectral variability analyses the spectrum is successfully
decomposed into a variable power-law component (PLC) and a reflection dominated
component (RDC). The former is highly variable while the latter is
approximately constant throughout the observation, leading to the well-known
spectral variability patterns. (Abridged)


title: A Face-On Tully-Fisher Relation

abstract:
  We construct the first "face-on" Tully-Fisher (TF) relation for 24 galaxies
with inclinations between 16 degrees and 41 degrees. The enabling measurements
are integral-field, echelle spectroscopy from the WIYN 3.5m telescope, which
yield accurate kinematic estimates of disk inclination to 15 degrees. Kinematic
inclinations are of sufficient accuracy that our measured TF scatter of 0.42
mag is comparable to other surveys even without internal-absorption
corrections. Three of four galaxies with significant kinematic and photometric
asymmetries also have the largest deviations from our TF relation, suggesting
that asymmetries make an important contribution to TF scatter. By measuring
inclinations below 40 degrees, we establish a direct path to linking this
scatter to the unprojected structure of disks and making non-degenerate
dynamical mass-decompositions of spiral galaxies.


title: Early results from the VIMOS VLT Deep Survey

abstract:
  The VIMOS VLT Deep Survey (VVDS) is underway to study the evolution of
galaxies, large scale structures and AGNs, from the measurement of more than
100000 spectra of faint objects. We present here the results from the first
epoch observations of more than 20000 spectra. The main challenge of the
program, the redshift measurements, is described, in particular entering the
``redshift desert'' in the range $1.5<z<3$ for which only very weak features
are observed in the observed wavelength range. The redshift distribution of a
magnitude limited sample brighter than $I_{AB}=24$ is presented for the first
time, showing a peak at a low redshift $z\sim0.7$, and a tail extending all the
way above $z=4$. The evolution of the luminosity function out to $z=1.5$ is
presented, with the LF of blue star forming galaxies carrying most of the
evolution, with L* changing by more than two magnitudes for this sub-sample.


title:
Observations of the pulsating subdwarf B star Feige 48: Constraints on
  evolution and companions

abstract:
  Since pulsating subdwarf B (sdBV or EC14026) stars were first discovered
(Kilkenny et al, 1997), observational efforts have tried to realize their
potential for constraining the interior physics of extreme horizontal branch
(EHB) stars. Difficulties encountered along the way include uncertain mode
identifications and a lack of stable pulsation mode properties. Here we report
on Feige 48, an sdBV star for which follow-up observations have been obtained
spanning more than four years, which shows some stable pulsation modes.
  We resolve the temporal spectrum into five stable pulsation periods in the
range 340 to 380 seconds with amplitudes less than 1%, and two additional
periods that appear in one dataset each. The three largest amplitude
periodicities are nearly equally spaced, and we explore the consequences of
identifying them as a rotationally split l=1 triplet by consulting with a
representative stellar model.
  The general stability of the pulsation amplitudes and phases allows us to use
the pulsation phases to constrain the timescale of evolution for this sdBV
star. Additionally, we are able to place interesting limits on any stellar or
planetary companion to Feige 48.


title:
Mass Segregation in Young Magellanic Clouds Star Clusters: Four Clusters
  observed with HST

abstract:
  We present the results of our investigation on the phenomenon of mass
segregation in young star clusters in the Magellanic Clouds. HST/WFPC2
observations on NGC 1818, NGC 2004 & NGC 2100 in the Large Magellanic Cloud and
NGC 330 in the Small Magellanic Cloud have been used for the application of
diagnostic tools for mass segregation: i) the radial density profiles of the
clusters for various mass groups and ii) their mass functions (MFs) at various
radii around their centres. All four clusters are found to be mass segregated,
but each one in a different manner. Specifically not all the clusters in the
sample show the same dependence of their density profiles on the selected
magnitude range, with NGC 1818 giving evidence of a strong such relation and
NGC 330 showing only a hint of the phenomenon. NGC 2004 did not also show any
significant signature of mass segregation in its density profiles. The MFs
radial dependence provides clear proof of the phenomenon for NGC 1818, NGC 2100
and NGC 2004, while for NGC 330 it gives only indications. An investigation on
the constraints introduced by the application of both diagnostic tools is
presented. We also discuss the problems related to the construction of a
reliable MF for a cluster and their impact on the investigation of the
phenomenon of mass segregation. We find that the MFs of these clusters as they
were constructed with two methods, are comparable to Salpeter's IMF. A
discussion is given on the dynamical status of the clusters and a test is
applied on the equipartition among several mass groups in them. Both showed
that the observed mass segregation in the clusters is of primordial nature.


title: Dissecting the knee - Air shower measurements with KASCADE

abstract:
  Recent results of the KASCADE air shower experiment are presented in order to
shed some light on the astrophysics of cosmic rays in the region of the knee in
the energy spectrum. The results include investigations of high-energy
interactions in the atmosphere, the analysis of the arrival directions of
cosmic rays, the determination of the mean logarithmic mass, and the unfolding
of energy spectra for elemental groups.


title: On the origin of the system PSR B1757-24/SNR G5.4-1.2

abstract:
  A scenario for the origin of the system PSR B1757-24/supernova remnant (SNR)
G5.4-1.2 is proposed. It is suggested that both objects are the remnants of a
supernova (SN) that exploded within a pre-existing bubble blown-up by a runaway
massive star (the SN progenitor) during the final (Wolf-Rayet) phase of its
evolution. This suggestion implies that (a) the SN blast centre was
significantly offset from the geometric centre of the wind-blown bubble (i.e.
from the centre of the future SNR), (b) the bubble was surrounded by a massive
wind-driven shell, and (c) the SN blast wave was drastically decelerated by the
interaction with the shell. Therefore, one can understand how the relatively
young and low-velocity pulsar PSR B1757-24 was able to escape from the
associated SNR G5.4-1.2 and why the inferred vector of pulsar transverse
velocity does not point away from the geometric centre of the SNR. A possible
origin of the radio source G5.27-0.9 (located between PSR B1757-24 and the SNR
G5.4-1.2) is proposed. It is suggested that G5.27-0.9 is a lobe of a low Mach
number (\simeq 1.7) jet of gas outflowing from the interior of G5.4-1.2 through
the hole bored in the SNR's shell by the escaping pulsar. It is also suggested
that the non-thermal emission of the comet-shaped pulsar wind nebula originates
in the vicinity of the termination shock and in the cylindric region of
subsonically moving shocked pulsar wind. The role of magnetized wind-driven
shells (swept-up during the Wolf-Rayet phase from the ambient interstellar
medium with the regular magnetic field) in formation of elongated axisymmetric
SNRs is discussed.


title: The Kinematics in the Cores of Low Surface Brightness Galaxies

abstract:
  Systematic effects on HI and Halpha long-slit observations make a measurement
of the inner slope of the dark matter density distribution difficult to
determine. Halos with constant density cores and ones with r^-1 profiles both
appear consistent with the data, although constant density cores generally
provide better fits. High-resolution, two-dimensional velocity fields remove
most of the systematic effects, yet as a result of noncircular and random
motions the inner slopes still cannot be accurately measured. Halo
concentration parameters provide a more useful test of cosmological models
because they are more tightly constrained by observations. The concentration
parameters for LSB galaxies appear consistent with, but on the low end of the
distribution predicted by CDM.


title:
Lucky Exposures: Diffraction limited astronomical imaging through the
  atmosphere

abstract:
  Through selection of short exposure images we achieve diffraction-limited
I-band imaging from well-figured ground-based telescopes as large as 2.5 m
diameter. The faint limiting magnitude and large isoplanatic patch size for the
Lucky Exposures technique at the Nordic Optical Telescope means that 25% of the
night sky is within range of a suitable reference star for I-band imaging.
Typically the 1%--10% of exposures with the highest Strehl ratios are selected.
When these exposures are shifted and added together, field stars in the
resulting images have Strehl ratios as high as 0.26 and full width at half
maximum flux (FWHM) as small as 90 milliarcseconds. Within the selected
exposures the isoplanatic patch is found to be 60 arcseconds in diameter at 810
nm wavelength. Images within globular clusters and of multiple stars from the
Nordic Optical Telescope using reference stars as faint as I~16 are presented.
  A new generation of CCDs (E2V L3Vision CCDs) were used in these observations,
allowing extremely low noise high frame-rate imaging with both fine pixel
sampling and a relatively wide field of view. The theoretical performance of
these CCDs is compared with the experimental results obtained.


title: Physical Processes in Star-Gas Systems

abstract:
  First we present a recently developed 3D chemodynamical code for galaxy
evolution from the K**2 collaboration. It follows the evolution of all
components of a galaxy such as dark matter, stars, molecular clouds and diffuse
interstellar matter (ISM). Dark matter and stars are treated as collisionless
N-body systems. The ISM is numerically described by a smoothed particle
hydrodynamics (SPH) approach for the diffuse (hot) gas and a sticky particle
scheme for the (cool) molecular clouds. Physical processs such as star
formation, stellar death or condensation and evaporation processes of clouds
interacting with the ISM are described locally. An example application of the
model to a star forming dwarf galaxy will be shown for comparison with other
codes. Secondly we will discuss new kinds of exotic chemodynamical processes,
as they occur in dense gas-star systems in galactic nuclei, such as
non-standard ``drag''-force interactions, destructive and gas producing stellar
collisions. Their implementation in 1D dynamical models of galactic nuclei is
presented. Future prospects to generalize these to 3D are work in progress and
will be discussed.


title:
Ground-Based Gamma-Ray Detection of High Energy Galactic Sources: An
  Update

abstract:
  I review the present status of ground-based gamma-ray astronomy,
concentrating on the population of galactic TeV sources. A number of new
telescope systems are now being completed, and promise to yield exciting new
discoveries, expanding rapidly the number of sources. The TeV galactic sources
today include a number of plerions, shell-type SNR, an X-ray binary, and also
one unidentified candidate. Their present status, and our understanding of
their TeV gamma-ray emission processes are summarised and some motivation
driving development of the field is outlined.


title: A White Dwarf Merger Paradigm for Supernovae and Gamma-Ray Bursts

abstract:
  Gamma-ray bursts can appear to be a hundred times as luminous as supernovae,
but their underlying energy source(s) have remained a mystery. However, there
has been evidence for some time now of an association of gamma-ray bursts with
supernovae of Type Ib and Ic, a fact which has been exploited by a number of
models, to explain the gamma-ray burst phenomenon. Here we interpret the
results of basic observations of SN 1987A and of pulsars in globular clusters,
to propose the energy source, which powers at least some long-duration
gamma-ray bursts, as core-collapse following the merger of two white dwarfs,
either as stars or stellar cores. The beaming and intrinsic differences among
gamma-ray bursts arise, at least in part, from differing amounts and
composition of the gas in the merged stellar common envelopes, with the more
energetic bursts resulting from mergers within less massive envelopes. In order
for the beams/jets associated with gamma-ray bursts to form in mergers within
massive common envelopes (as with SN 1987A), much of the intervening stellar
material in the polar directions must be cleared out by the time of
core-collapse, or the beams/jets themselves must clear their own path. The
core-collapse produces supernovae of Type Ib, Ic, or II (as with SN 1987A, a
SNa IIp), leaving a weakly magnetized neutron star remnant with a spin period
near 2 milliseconds. There is no compelling reason to invoke any other model to
account for gamma-ray bursts. Far from being an unusual event, SN 1987A is
typical, having the same merger source of initiation as 95% of all supernovae,
the rare exceptions being Ia's induced via gradual accretion from a binary
companion, and Fe catastrophe II's.


title:
The Recent Cluster Formation Histories of NGC 5253 and NGC 3077:
  Environmental Impact on Star Formation

abstract:
  We present multicolor photometry of bright star cluster candidates in the
nearby starburst galaxies NGC 3077 and NGC 5253, observed with the Hubble Space
Telescope Wide Field and Planetary Camera 2 in both broadband (F300W, F547M and
F814W) and narrowband (F487N and F656N) filters. By comparing the photometry
with theoretical population synthesis models, we estimate the age and mass of
each star cluster, which provides constraints on the recent star formation
histories of the host galaxies. We compare the star cluster populations in
these dwarf starburst galaxies to those of the nuclear starburst in the barred
spiral M 83, and discuss implications for our understanding of the nature and
evolution of starburst events.


title: Charged-particle decay and suppression of small-scale power

abstract:
  We study the suppression of the small-scale power spectrum due to the decay
of charged matter to dark matter prior to recombination. Prior to decay, the
charged particles couple to the photon-baryon fluid and participate in its
acoustic oscillations. However, after decaying to neutral dark matter the
photon-baryon fluid is coupled only gravitationally to the newly-created dark
matter. This generically leads to suppression of power on length scales that
enter the horizon prior to decay. For decay times of approximately 3.5 years
this leads to suppression of power on subgalactic scales, bringing the observed
number of Galactic substructures in line with observation. Decay times of a few
years are possible if the dark matter is purely gravitationally interacting,
such as the gravitino in supersymmetric models or a massive Kaluza-Klein
graviton in models with universal extra dimensions.


title: Massive black hole seeds from low angular momentum material

abstract:
  (ABRIDGED) We present a model in which the seeds of supermassive black holes
form from the lowest angular momentum gas in proto-galaxies at high redshift.
We show that this leads to a correlation between black hole masses and spheroid
properties, as observed today. We assume that gas in early-forming, rare halos
has a distribution of specific angular momentum similar to that expected for
dark matter halos. This distribution has a significant low angular momentum
tail which implies that every proto-galaxy should contain gas that ends up in a
high-density disc. In halos more massive than a critical threshold of
\~10^8Msun, the discs are gravitationally unstable, and experience an efficient
Lin-Pringle viscosity that allows mass inflow. This process continues until the
first massive stars disrupt the disc. Black holes are created with a
characteristic mass of ~10^5 Msun, independent of the redshift of formation.
This serves as a lower bound for black-hole masses in galaxies today. The
comoving mass density of black hole seeds grows with time, and saturates when
cosmic reionization stops gas cooling in these low-mass systems. By z~15, the
comoving mass density becomes comparable to that inferred from observations,
with room for appropriate additional luminous growth during a later quasar
accretion phase. Hierarchical merging after z~15 naturally leads to a linear
correlation between black-hole mass and stellar spheroid mass, with negligible
black hole masses in disc-dominated galaxies.


title: The Luminosity and Angular Distributions of Long GRBs

abstract:
  The realization that the total energy of GRBs is correlated with their jet
break angles motivates the search for a similar relation between the peak
luminosity, $L$, and the jet break angles, $L\propto\theta^{-2}$. Such a
relation implies that the GRB luminosity function determines the angular
distribution. We re-derive the GRB luminosity function using the BATSE peak
flux distribution and compare the predicted distribution with the observed
redshift distribution. The luminosity function can be approximated by a broken
power law with a break peak luminosity of $4.4 \times 10^{51}$ erg/sec, a
typical jet angle of 0.12 rad and a local GRB rate of $0.44 h_{65}^{3}$
Gpc$^{-3}$yr$^{-1}$. The angular distribution implied by $L\propto\theta^{-2}$
agrees well with the observed one, and implies a correction factor to the local
rate due to beaming of $75\pm25$ (instead of 500 as commonly used). The
inferred overall local GRB rate is $33\pm11 h_{65}^{3}$ Gpc$^{-3}$yr$^{-1}$.
The luminosity function and angle distribution obtained within the universal
structured jet model, where the angular distribution is essentially $\propto
\theta$ and hence the luminosity function must be $\propto L^{-2}$, deviate
from the observations at low peak fluxes and, correspondingly, at large angles.
The corresponding correction factor for the universal structure jet is $\sim 20
\pm 10$.


title: Cosmic and Galactic Neutrino Backgrounds from Thermonuclear Sources

abstract:
  We estimate energy spectra and fluxes at the Earth's surface of the cosmic
and Galactic neutrino backgrounds produced by thermonuclear reactions in stars.
The extra-galactic component is obtained by combining the most recent estimates
of the cosmic star formation history and the stellar initial mass function with
accurate theoretical predictions of the neutrino yields all over the
thermonuclear lifetime of stars of different masses. Models of the structure
and evolution of the Milky Way are used to derive maps of the expected flux
generated by Galactic sources as a function of sky direction. The predicted
neutrino backgrounds depend only slightly on model parameters. In the relevant
50 keV-10 MeV window, the total flux of cosmic neutrinos ranges between 20 and
65 particles per square cm per s. Neutrinos reaching the Earth today have been
typically emitted at redshift z~2. Their energy spectrum peaks at E~0.1-0.3
MeV. The energy and entropy densities of the cosmic background are negligible
with respect to the thermal contribution of relic neutrinos originated in the
early universe. In every sky direction, the cosmic background is outnumbered by
the Galactic one, whose integrated flux amounts to 300-1000 particles per
square cm per s. The emission from stars in the Galactic disk contributes more
than 95 per cent of the signal.


title:
The radio galaxy K-z relation: the 10^12 Msol mass limit; masses of
  galaxies from the L_K luminosity, up to z >4

abstract:
  The narrow K-z relation of powerful radio galaxies in the Hubble K diagram is
often attributed to the stellar populations of massive elliptical galaxies.
Extended over a large range of redshifts (0<z<4), it is difficult to estimate
masses at high z from galaxy evolution. In the present paper, we propose to
estimate the stellar masses of galaxies using the galaxy evolution model
PEGASE. We use star formation scenarios that successfully fit faint galaxy
counts and z=0 galaxy templates. They also allow to estimate valid photometric
redshifts. The baryonic mass of the initial gas cloud M_bar is then derived.
The K-z relation is remarkably reproduced by our scenario for elliptical
galaxies of baryonic mass M_(bar,max)=10^12 Msol, at all z up to z=4.
M_(bar,max) is also the maximum mass limit of all types of galaxies. Using
another IMF, even a top-heavy one, does not alter our conclusions. The high
value of M_(bar,max) observed at z > 4 implies that massive clouds were already
formed at early epochs. We also find that the M_(bar,max) limit is similar to
the critical mass M_crit of a self-gravitating cloud regulated by cooling (Rees
& Ostriker, 1977; Silk, 1977). Moreover, the critical size r_crit = 75 Kpc is
remarkably close to the typical diameter of Ly_alpha haloes surrounding distant
radio galaxies. This confirms the validity of the method of baryonic mass
determination based on the K-band luminosity. A puzzling question that remains
to be answered is the short time-scale of mass-accumulation required to form
such massive galaxies at z=4. We discuss the dispersion of the K-z relation and
the link between the active nucleus and a large stellar mass.


title: Reconstructing the primordial power spectrum - a new algorithm

abstract:
  We propose an efficient and model independent method for reconstructing the
primordial power spectrum from Cosmic Microwave Background (CMB) and large
scale structure observations. The algorithm is based on a Monte Carlo principle
and therefore very simple to incorporate into existing codes such as Markov
Chain Monte Carlo. The algorithm has been used on present cosmological data to
test for features in the primordial power spectrum. No significant evidence for
features is found, although there is a slight preference for an overall bending
of the spectrum, as well as a decrease in power at very large scales. We have
also tested the algorithm on mock high precision CMB data, calculated from
models with non-scale invariant primordial spectra. The algorithm efficiently
extracts the underlying spectrum, as well as the other cosmological parameters
in each case. Finally we have used the algorithm on a model where an artificial
glitch in the CMB spectrum has been imposed, like the ones seen in the WMAP
data. In this case it is found that, although the underlying cosmological
parameters can be extracted, the recovered power spectrum can show significant
spurious features, such as bending, even if the true spectrum is scale
invariant.


title: Near infrared imaging of NGC2316

abstract:
  In the present paper we present JHK photometric results of the young embedded
cluster NGC 2316. We construct the cluster radial profile from which we
determine a radius of 0.63 pc. We find 189 $\pm$ 29 cluster members in an
extinction limited sub-sample of the survey, 22 $\pm$ 19 of which are possibly
substellar. An average extinction of 4.5 visual magnitudes is derived using
(H-K) colours of control fields. This extinction is due to the presence of
residual parental molecular cloud. NGC 2316 presents 16% source fraction of
excess emission which is consistent with other results from clusters with an
age of 2-3 Myr. This age is consistent with the distribution of sources in the
colour-magnitude diagram when compared to theoretical isochrones, and the
overall shape of the cluster KLF. The substellar population of the cluster is
similar or smaller than that observed for other embedded clusters and the
stellar objects dominate the cluster membership.


title:
IRFM T_eff calibrations for cluster and field giants in the Vilnius,
  Geneva, RI(C) and DDO photometric systems

abstract:
  Based on a large sample of disk and halo giant stars, for which accurate
effective temperatures derived through the InfraRed Flux Method (IRFM) exist, a
calibration of the temperature scale in the Vilnius, Geneva, RI(C) and DDO
photometric systems is performed. We provide calibration formulae for the
metallicity dependent T_eff vs color relations as well as grids of intrinsic
colors and compare them with other calibrations. Photometry, atmospheric
parameters and reddening corrections for the stars of the sample have been
updated with respect to the original sources in order to reduce the dispersion
of the fits. Application of our results to Arcturus leads to an effective
temperature in excellent agreement with the value derived from its angular
diameter and integrated flux. The effects of gravity on these T_eff vs color
relations are also explored by taking into account our previous results for
dwarf stars.


title:
Constraining vacuum gap models of pulsar radio emission using the
  intensity modulation index

abstract:
  Recent observations suggest that the level of pulse-to-pulse intensity
modulation observed in a given radio pulsar may depend on its period and period
derivative. Such a ``modulation index relationship'' (MIR) may be an important
tool for determining the physical processes behind the radio emission. In the
context of sparking gap models, the exact functional form of the MIR depends on
the physical processes occurring on the surface of the neutron star in the
region known as the ``vacuum gap.'' Several possible vacuum gap models are
studied here in order to determine the expected MIR for a given model. Current
observations are consistent with two of the four models studied: the curvature
radiation driven vacuum gap and the curvature radiation driven near threshold
vacuum gap (CR-NTVG). It is shown that the inverse Compton scattering driven
vacuum gap models are not supported by the current data. Given that the current
data best supports the CR-NTVG model, its possible that all pulsars have strong
(approx 10^13 G) surface magnetic fields.


title: Cosmic acceleration vs axion-photon mixing

abstract:
  Axion-photon mixing has been proposed as an alternative to acceleration as
the explanation for supernovae dimming. We point out that the loss of photons
due to this mixing will induce a strong asymmetry between the luminosity,
d_L(z), and angular-diameter distance, d_A(z), since the latter is unaffected
by mixing. In a first search for such an asymmetry we introduce a dimensionless
mixing amplitude lambda so that lambda=0 if no photons are lost and lambda = 1
if axion-photon mixing occurs. The best-fit to SNIa and radio galaxy data is
lambda = -0.3^{+0.6}_{-0.4} (95% CL), corresponding to an unphysical, negative,
mixing length. This same argument limits the attenuation of light from
supernovae due to dust. We show that future d_L and d_A data from SNAP and
galaxy surveys such as DEEP2 and KAOS will detect or rule out mixing at more
than 5-sigma, almost independently of the dark energy dynamics. Finally we
discuss the constraints from the near maximal polarisation of the gamma-ray
burst (GRB) GRB021206. Since mixing reduces the polarisation of distant
sources, future observations of high redshift GRBs may provide orthogonal
constraints on axion-photon mixing and related scenarios.


title:
Early Hierarchical Formation of Massive Galaxies Triggered By
  Interactions

abstract:
  To address the problem concerning the early formation of stars in massive
galaxies, we present the results of a semi-analytic model of galaxy formation
which includes a physical description of starbursts triggered by galaxy
interactions. These originate from the destabilization of cold galactic gas
occurring in galaxy encounters, which in part feeds the accretion onto black
holes powering quasars, and in part drives circumnuclear starsbursts at
redshifts $z\approx 2-4$, preferentially in massive objects. This speeds up the
formation of stars in massive galaxies at high redshifts without altering it in
low mass galactic halos. Thus, at intermediate $z\approx 1.5-2$ we find that a
considerable fraction of the stellar content of massive galaxies is already in
place, at variance with the predictions of previous hierarchical models. The
resulting high-$z$ star formation rate and B-band luminosity functions, and the
luminosity and redshift distribution of galaxies in K-band at $z\lesssim 2$ are
all in good agreement with the existing observations concerning the bright
galaxy population.


title:
Internal dynamics of the radio--halo cluster A2219: a multi-wavelength
  analysis

abstract:
  We present the results of the dynamical analysis of the rich, hot, and X-ray
very luminous galaxy cluster A2219, containing a powerful diffuse radio-halo.
Our analysis is based on new redshift data for 27 galaxies in the cluster
region, measured from spectra obtained at the TNG, with the addition of other
105 galaxies recovered from reduction of CFHT archive data in a cluster region
of about 5 arcmin radius (about 0.8 Mpc h^-1 at the cluster distance) centered
on the cD galaxy. The investigation of the dynamical status is also performed
by using X-ray data stored in the Chandra archive. Further, valuable
information comes from other bands - optical photometric, infrared, and radio
data - which are analyzed and/or discussed, too. Our analyses support the view
of the connection between extended radio emission and merging phenomena in
galaxy clusters.


title: 'Notches' in the Profiles of Bright Pulsars

abstract:
  We discuss the discovery of `notch-like' features in the mean pulse profile
of the nearby, bright pulsar B0950+08. We compare these low-level features with
those previously seen in the pulse profiles of pulsars J0437-4715 and B1929+10.
While J0437-4715 is a binary millisecond pulsar and B0950+08 and B1929+10 are
isolated, slow pulsars, all three pulsars are nearby and very bright.
Furthermore, all three have detectable emission over an unusually wide range of
pulse phase. We describe the similar properties of the notch features seen in
all three pulsars and discuss possible interpretations.


title: Adiabatic relativistic models for the jets in the radio galaxy 3C 31

abstract:
  We present a general approach to the modelling of the brightness and
polarization structures of adiabatic, decelerating relativistic jets, based on
the formalism of Matthews & Scheuer (1990). We compare the predictions of
adiabatic jet models with deep, high-resolution observations of the radio jets
in the FR I radio galaxy 3C 31. Adiabatic models require coupling between the
variations of velocity, magnetic field and particle density. They are therefore
more tightly constrained than the models previously presented for 3C 31 by
Laing & Bridle (2002). We show that adiabatic models provide a poorer
description of the data in two crucial respects: they cannot reproduce the
observed magnetic-field structures in detail, and they also predict too steep a
brightness decline along the jets for plausible variations of the jet velocity.
We find that the innermost regions of the jets show the strongest evidence for
non-adiabatic behaviour, and that the adiabatic models provide progressively
better descriptions of the jet emission at larger distances from the galactic
nucleus. We briefly discuss physical processes which might contribute to this
non-adiabatic behaviour. In particular, we develop a parameterized description
of distributed particle injection, which we fit to the observed total
intensities. We show that particles are preferentially injected where bright
X-ray emission is observed, and where we infer that the jets are
over-pressured.


title:
Magnetically Driven Accretion Flows in the Kerr Metric II: Structure of
  the Magnetic Field

abstract:
  We present a detailed analysis of the magnetic field structure found in
general relativistic 3D MHD simulations of accreting tori in the Kerr metric
with different black hole spins. Among the properties analyzed are the field
strength as a function of position and black hole spin, the shapes of field
lines, the degree to which they connect different regions, and their degree of
tangling. We investigate prior speculations about the structure of the magnetic
fields and discuss how frequently certain configurations are seen in the
simulations. We also analyze the distribution of current density, with a view
toward identifying possible locations for magnetic energy dissipation.


title:
H$\alpha$-Derived Star-Formation Rates for the z=0.84 Galaxy Cluster
  CLJ0023+0423B

abstract:
  We present H$\alpha$-derived star-formation rates (SFRs) for the galaxy
cluster CL J0023+0423B at $z = 0.845$. Our $3\sigma$ flux limits corresponds to
a star-formation rate of 0.24 \smy, and our minimum reliable H$\alpha$ + [N II]
equivalent width is $> 10$ \AA, demonstrating that near-infrared narrow-band
imaging can sample the star-forming galaxy population in distant clusters.
Comparison with spectroscopy shows that the number of false detections is low
($9 \pm 6$%) and that our H$\alpha$ equivalent widths are correlated with
spectroscopically determined [O II] equivalent widths. A magnitude-limited
spectroscopic survey conducted over the same area missed 70% of the
star-forming galaxies and 65% of the integrated star formation. Using Hubble
Space Telescope Wide Field Planetary Camera 2 Archive images, we fit Sersic
profiles to all galaxies with significant narrow-band equivalent widths and
find that equivalent width decreases as the steepness of galaxy profile
increases. We find no significant population of early type galaxies with
ongoing star formation. The integrated SFR per cluster mass of CL J0023+0423B
is a factor of ten higher than that of the three $z \sim 0.2$ clusters in the
literature with available H$\alpha$ observations. A larger sample of $z \sim
0.8$ clusters spanning a range of cluster masses is needed to determine whether
this variation is due to a difference in cluster mass or redshift.


title:
Mapping small-scale temperature and abundance structures in the core of
  the Perseus cluster

abstract:
  We report further results from a 191 ks Chandra observation of the core of
the Perseus cluster, Abell 426. The emission-weighted temperature and abundance
structure is mapped detail. There are temperature variations down to ~1 kpc in
the brightest regions. Globally, the strongest X-ray surface brightness
features appear to be caused by temperature changes. Density and temperature
changes conspire to give approximate azimuthal balance in pressure showing that
the gas is in hydrostatic equilibrium. Si, S, Ar, Ca, Fe and Ni abundance
profiles rise inward from about 100 kpc, peaking at about 30-40 kpc. Most of
these abundances drop inwards of the peak, but Ne shows a central peak, all of
which may be explained by resonance scattering. There is no evidence for a
widespread additional cooler temperature component in the cluster with a
temperature greater than a factor of two from the local temperature. There is
however evidence for a widespread hard component which may be nonthermal. The
temperature and abundance of gas in the cluster is observed to be correlated in
a manner similar to that found between clusters.


title: Perturbations in cosmologies with a scalar field and a perfect fluid

abstract:
  We study the properties of cosmological density perturbations in a
multi-component system consisting of a scalar field and a perfect fluid. We
discuss the number of degrees of freedom completely describing the system,
introduce a full set of dynamical gauge-invariant equations in terms of the
curvature and entropy perturbations, and display an efficient formulation of
these equations as a first-order system linked by a fairly sparse matrix. Our
formalism includes spatial gradients, extending previous formulations
restricted to the large-scale limit, and fully accounts for the evolution of an
isocurvature mode intrinsic to the scalar field. We then address the issue of
the adiabatic condition, in particular demonstrating its preservation on large
scales. Finally, we apply our formalism to the quintessence scenario and
clearly underline the importance of initial conditions when considering
late-time perturbations. In particular, we show that entropy perturbations can
still be present when the quintessence field energy density becomes
non-negligible.


title: Evidence for Toroidal B-Field Structures in BL Lac Objects

abstract:
  If the transverse jet B fields observed in BL Lac objects on parsec scales
represent the toroidal component of the jet B fields, this should give rise to
rotation-measure gradients across the jets, due to the systematic change in the
line-of-sight component of the jet B field. We have found evidence for such
rotation-measure gradients in one-third to one-half of the 1 Jy BL Lac objects
we have analyzed. We present and discuss these new results, together with some
of their implications for our understanding of the parsec-scale jets of AGN.