title: The Spatial Structure of the beta Pictoris Gas Disk

abstract:
  We have used VLT/UVES to spatially resolve the gas disk of beta Pictoris. 88
extended emission lines are observed, with the brightest coming from Fe I, Na I
and Ca II. The extent of the gas disk is much larger than previously
anticipated; we trace Na I radially from 13 AU out to 323 AU and Ca II to
heights of 77 AU above the disk plane, both to the limits of our observations.
The degree of flaring is significantly larger for the gas disk than the dust
disk. A strong NE/SW brightness asymmetry is observed, with the SW emission
being abruptly truncated at 150-200 AU. The inner gas disk is tilted about 5
degrees with respect to the outer disk, similar to the appearance of the disk
in light scattered from dust. We show that most, perhaps all, of the Na I
column density seen in the 'stable' component of absorption, comes from the
extended disk. Finally, we discuss the effects of radiation pressure in the
extended gas disk and show that the assumption of hydrogen, in whatever form,
as a braking agent is inconsistent with observations.


title:
The Dependence of the Galaxy Luminosity Function on Large-Scale
  Environment

abstract:
  A basic assumption in current halo occupation model is that the properties of
a galaxy depend only on the mass of its dark matter halo. An important
consequence of this is that the segregation of the galaxy population by
large-scale environment is entirely due to the environmental dependence of the
halo population. In this paper we use such a model to predict how the galaxy
luminosity function depends on large-scale environment. The latter is
represented by the density contrast (delta) averaged over a spherical volume of
radius R=8Mpc/h. The model predicts that the Schechter function is a good
approximation to the luminosity functions of galaxies brighter than ~10^9
h^{-2}L_sun (b_j-band) in virtually all environments. The characteristic
luminosity, L^{\star}, increases moderately with \delta. The faint-end slope,
\alpha, on the other hand, is quite independent of $\delta$. However, when
splitting the galaxy population into early and late types, it is found that for
late-types \alpha is virtually constant, whereas for early-types \alpha
increases from ~-0.3 in underdense regions (\delta~-0.5) to ~-0.8 in highly
overdense regions with \delta ~ 10. The luminosity function at L_{b_j}<10^9
h^{-2} L_sun is significantly steeper than the extrapolation of the Schechter
function that fits the brighter galaxies. This steepening is more significant
for early-types and in low-density environments. The model also predicts that
the luminosity density and mass density are closely correlated. The relation
between the two is monotonic but highly non-linear. This suggests that one can
use the luminosity density, averaged over a large volume, to rank the mass
density. This, in turn, allows the environmental effects predicted here to be
tested by observations.


title: Testing the energy scale of the CELESTE experiment

abstract:
  The uncertainties on the absolute energy scale of the CELESTE experiment
affect the constraints CELESTE can impose on > 30 GeV gamma-ray emission
models. To date, these uncertainties have been of order 30 %. The optical
throughputs of the atmosphere and the detector are key to understanding the
energy scale. We are comparing CELESTE photomultiplier anode currents measured
for bright stars with predictions from the detector simulation. In these
studies we include data from recently installed radiometers, and from the LIDAR
operating on the site.


title:
Extraction of cluster parameters from Sunyaev-Zeldovich effect
  observations with simulated annealing optimization

abstract:
  We present a user-friendly tool for the analysis of data from
Sunyaev-Zeldovich effect observations. The tool is based on the stochastic
method of simulated annealing, and allows the extraction of the central values
and error-bars of the 3 SZ parameters, Comptonization parameter, y, peculiar
velocity, v_p, and electron temperature, T_e. The f77-code SASZ will allow any
number of observing frequencies and spectral band shapes. As an example we
consider the SZ parameters for the COMA cluster.


title:
The X-ray flaring activity of the galactic nucleus observed with
  XMM-Newton

abstract:
  We report the results of XMM-Newton observations of Sgr A*, the radiative
counterpart of the massive black hole at the nucleus of our Galaxy, performed
in the frame of the guaranteed time survey program of the Galactic Center
region. The discovery of bright X-ray flares from Sgr A* with Chandra in
October 2000 have opened new perspectives to understand the processes at work
in this object and in general in black holes accreting at low accretion rates.
We report here the important results obtained with XMM-Newton on the Sgr A*
high-energy flaring activity and we discuss the implications on the models and
the future observational perspectives.


title:
Mid-IR observations of Galactic HII regions: constraining ionizing
  spectra of massive stars and the nature of the observed excitation sequences

abstract:
  Extensive photoionization model grids for single star HII regions using a
variety of recent state-of-the-art stellar atmosphere models have been computed
with the main aim of constraining/testing their predicted ionizing spectra
against recent ISO mid-IR observations of Galactic HII regions, which probe the
ionizing spectra between ~ 24 and 41 eV thanks to Ne, Ar, and S fine structure
lines. Particular care has been paid to examining in detail the dependences of
the nebular properties on the numerous nebular parameters (mean ionization
parameter U, abundances, dust etc.) which are generally unconstrained for the
objects considered here. Finally we have examined which parameters are chiefly
responsible for the observed mid-IR excitation sequences. The galactic gradient
of metallicity changing the shape of the stellar emission is found to be one of
the drivers for the excitation sequence of Galactic HII regions, the actual
contribution of this effect being finally atmosphere model dependent. We find
that the dispersion of Teff between different HII regions due to statistical
sampling of the IMF plus additional scatter in the ionization parameter are
probably the dominant driver for the observed excitation scatter.


title: IceCube-Plus: An Ultra-High Energy Neutrino Telescope

abstract:
  While the first kilometer-scale neutrino telescope, IceCube, is under
construction, alternative plans exist to build even larger detectors that will,
however, b e limited by a much higher neutrino energy threshold of 10 PeV or
higher rather than 10 to 100 GeV. These future projects detect radio and
acoustic pulses as w ell as air showers initiated by ultra-high energy
neutrinos. As an alternative, we here propose an expansion of IceCube, using
the same strings, placed on a gri d with a spacing of order 500 m. Unlike other
proposals, the expanded detector uses methods that are understood and
calibrated on atmospheric neutrinos. Atmosp heric neutrinos represent the only
background at the energies under consideratio n and is totally negligible.
Also, the cost of such a detector is understood. We conclude that supplementing
the 81 IceCube strings with a modest number of addi tional strings spaced at
large distances can almost double the effective volume of the detector.
Doubling the number of strings on a 800 m grid can deliver a d etector that
this a factor of 5 larger for horizontal muons at modest cost.


title: Another single hydrogen-rich Wolf-Rayet star in the SMC?

abstract:
  A 12th Wolf-Rayet star in the SMC has recently been discovered by Massey et
al. (2003). In order to determine its spectral type and a preliminary binary
status, we obtained 3 high signal-to-noise spectra separated in time at the
ESO-NTT. Compared to other WR stars in the SMC, SMC-WR12 appears to belong to
the subgroup of faint, single and hydrogen-rich WN stars. We discuss the
evolutionary status of WR12 and show that relatively low mass rotating
progenitors can better account for the properties of single hydrogen-rich WN
stars in the SMC.


title: Galaxy Scaling Relations as a Result of Secular Evolution

abstract:
  The secular evolution process which slowly transforms the morphology of a
given galaxy over its lifetime through mostly internal dynamical mechanisms
could naturally account for most of the observed properties of physical
galaxies (Zhang 2003a). As an emerging paradigm for galaxy evolution, its
dynamical foundations had been established in the past few years (Zhang 1996,
1998, 1999). In this paper, we explore further implications of the secular
morphological evolution process in reproducing the well-known scaling relations
of galaxies.


title: Fitting Pulsar Wind Tori

abstract:
  CXO imaging has shown that equatorial tori, often with polar jets, are very
common in young pulsar wind nebulae (PWNe). These structures are interesting
both for what they reveal about the relativistic wind itself and for the
(nearly) model-independent measurement of the neutron star spin orientation
they provide. The later is a particularly valuable probe of pulsar emission
models and of neutron star physics.We describe here a procedure for fitting
simple 3-D torus models to the X-ray data which provides robust estimates of
the geometric parameters. An application to 6 PWN tori gives orientations, PWN
shock scales and post-shock wind speeds along with statistical errors. We
illustrate the use of these data by commenting on the implications for kick
physics and for high energy beaming models.


title:
First results of IBIS/ISGRI Cygnus X-3 monitoring during INTEGRAL PV
  phase

abstract:
  We report on preliminary results of IBIS/ISGRI serendipitous observations of
Cygnus X-3 in the 15-100 keV energy range during the INTEGRAL Performance and
Verification phase. This peculiar microquasar was inside IBIS/ISGRI field of
view at a ~ 9 degrees distance from the pointing direction during Cygnus X-1
staring observations in November and December 2002. We analyzed observations
from 27 November 2002 to 8 December 2002 with an effective on source exposure
time of ~ 300 kiloseconds. Cyg X-3 was always significantly detected in the
15-40 and 40-100 keV energy bands during single exposures lasting between 30
minutes and one hour. The source light curve shows the characteristic 4.8-hour
modulation with a shape consistent with a standard template. The two light
curves' phase zero have no measurable offset and their values are consistent
with historical ephemeris. These results show that even at this early stage of
the mission, IBIS/ISGRI is capable of producing high quality scientific results
on highly off axis, relatively bright targets.


title: Mergers and Non-Thermal Processes in Clusters

abstract:
  Clusters of galaxies generally form by the gravitational merger of smaller
clusters and groups. Mergers drive shocks in the intracluster gas which heat
the intracluster gas. Mergers disrupt cluster cooling cores. Mergers produce
large, temporary increases in the X-ray luminosities and temperatures of
cluster; such merger boost may bias estimates of cosmological parameters from
clusters. Chandra observations of the X-ray signatures of mergers, particularly
"cold fronts," will be discussed. X-ray observations of shocks can be used to
determine the kinematics of the merger. As a result of particle acceleration in
shocks and turbulent acceleration following mergers, clusters of galaxies
should contain very large populations of relativistic electrons and ions.
Observations and models for the radio, extreme ultraviolet, hard X-ray, and
gamma-ray emission from nonthermal particles accelerated in these shocks are
described.


title:
Multiwavelength Observations of Strong Flares From the TeV-Blazar 1ES
  1959+650

abstract:
  Following the detection of strong TeV gamma-ray flares from the BL Lac object
1ES 1959+650 with the Whipple 10 m Cherenkov telescope on May 16 and 17, 2002,
we performed intensive Target of Opportunity (ToO) radio, optical, X-ray and
TeV gamma-ray observations from May 18, 2002 to August 14, 2002. Observations
with the X-ray telescope RXTE and the Whipple and HEGRA gamma-ray telescopes
revealed several strong flares, enabling us to sensitively test the
X-ray/gamma-ray flux correlation properties. Although the X-ray and gamma-ray
fluxes seemed to be correlated in general, we found an ``orphan'' gamma-ray
flare that was not accompanied by an X-ray flare. After describing in detail
the radio (UMRAO, VLA), optical (Boltwood, Abastumani), X-ray (RXTE) and
gamma-ray (Whipple, HEGRA) light curves and Spectral Energy Distributions
(SEDs) we present initial modeling of the SED with a simple Synchrotron
Self-Compton (SSC) model. With the addition of another TeV blazar with good
broadband data, we consider the set of all TeV blazars to begin to look for a
connection of the jet properties to the properties of the central accreting
black hole thought to drive the jet. Remarkably, the temporal and spectral
X-ray and gamma-ray emission characteristics of TeV blazars are very similar,
even though the masses estimates of their central black holes differ by up to
one order of magnitude.


title: RR Lyrae Variables in Globular Clusters and Nearby Galaxies

abstract:
  I point out that the Oosterhoff dichotomy for globular cluster and field RR
Lyrae (RRL) stars may place the strongest constraints so far on the number of
dwarf spheroidal-like protogalactic fragments that may have contributed to the
formation of the Galactic halo. The first calibration of the RRL
period-luminosity relation in I, J, H, K taking evolutionary effects into
account is provided. Problems in the interpretation of RRL light curves and
evolutionary properties are briefly reviewed.


title:
GRAPE-SPH Chemodynamical Simulation of Elliptical Galaxies I: Evolution
  of Metallicity Gradients

abstract:
  We simulate the formation and chemodynamical evolution of 124 elliptical
galaxies by using a GRAPE-SPH code that includes various physical processes
associated with the formation of stellar systems: radiative cooling, star
formation, feedback from Type II and Ia supernovae and stellar winds, and
chemical enrichment. In our CDM-based scenario, galaxies form through the
successive merging of sub-galaxies with various masses. Their merging histories
vary between a major merger at one extreme, and a monolithic collapse of a
slow-rotating gas cloud at the other extreme. The basic processes driving the
evolution of the metallicity gradients are as follows: i) destruction by
mergers to an extent dependent on the progenitor mass ratio. ii) regeneration
when strong central star formation is induced at a rate dependent on the gas
mass of the secondary. iii) slow evolution as star formation is induced in the
outer regions through late gas accretion. We succeed in reproducing the
observed variety of the radial metallicity gradients. The average gradient dlog
Z/dlog r ~ -0.3 with dispersion of +- 0.2 and no correlation between gradient
and galaxy mass are consistent with observations of Mg2 gradients. The variety
of the gradients stems from the difference in the merging histories. Galaxies
that form monolithically have steeper gradients, while galaxies that undergo
major mergers have shallower gradients. Thus merging histories can, in
principle, be inferred from the observed metallicity gradients of present-day
galaxies. The observed variation in the metallicity gradients cannot be
explained by either monolithic collapse or by major merger alone. Rather it
requires a model in which both formation processes arise, such as the present
CDM scheme.


title: Migration of extrasolar planets to large orbital radii

abstract:
  Observations of structure in circumstellar debris discs provide
circumstantial evidence for the presence of massive planets at large (several
tens of au) orbital radii, where the timescale for planet formation via core
accretion is prohibitively long. Here, we investigate whether a population of
distant planets can be produced via outward migration subsequent to formation
in the inner disc. Two possibilities for significant outward migration are
identified. First, cores that form early at radii of around 10 au can be
carried to larger radii via gravitational interaction with the gaseous disc.
This process is efficient if there is strong mass loss from the disc - either
within a cluster or due to photoevaporation from a star more massive than the
Sun - but does not require the extremely destructive environment found, for
example, in the core of the Orion Nebula. We find that, depending upon the disc
model, gas disc migration can yield massive planets (several Jupiter masses) at
radii of around 20-50 au. Second, interactions within multiple planet systems
can drive the outer planet into a large, normally highly eccentric orbit. A
series of scattering experiments suggests that this process is most efficient
for lower mass planets within systems of unequal mass ratio. This mechanism is
a good candidate for explaining the origin of relatively low mass giant planets
in eccentric orbits at large radii.


title: Massive Young Clusters

abstract:
  In the last decade we have come to realize that the traditional
classification of stellar clusters into open and globular clusters cannot be
easily extended beyond the realm of the Milky Way, and that even for our Galaxy
it is not fully valid. The main failure of the traditional classification is
the existence of Massive Young Clusters (MYCs), which are massive like Globular
Clusters (GCs) but also young like open clusters. We describe here the mass and
age distributions of clusters in general with an emphasis on MYCs. We also
discuss the issue of what constitutes a cluster and try to establish a general
classification scheme.


title: Gravitational lensing as a contaminant of the gravity wave signal in CMB

abstract:
  Gravity waves (GW) in the early universe generate B-type polarization in the
cosmic microwave background (CMB), which can be used as a direct way to measure
the energy scale of inflation. Gravitational lensing contaminates the GW signal
by converting the dominant E polarization into B polarization. By
reconstructing the lensing potential from CMB itself one can decontaminate the
B mode induced by lensing. We present results of numerical simulations of B
mode delensing using quadratic and iterative maximum-likelihood lensing
reconstruction methods as a function of detector noise and beam. In our
simulations we find the quadratic method can reduce the lensing B noise power
by up to a factor of 7, close to the no noise limit. In contrast, the iterative
method shows significant improvements even at the lowest noise levels we
tested. We demonstrate explicitly that with this method at least a factor of 40
noise power reduction in lensing induced B power is possible, suggesting that
T/S=10^-6 may be achievable in the absence of sky cuts, foregrounds, and
instrumental systematics. While we do not find any fundamental lower limit due
to lensing, we find that for high-sensitivity detectors residual lensing noise
dominates over the detector noise.


title:
Inter-Network magnetic fields observed during the minimum of the solar
  cycle

abstract:
  We analyze a time series of high angular resolution magnetograms of quiet Sun
Inter-Network (IN) magnetic fields. These magnetograms have a spatial
resolution better than 0.5 arcsec, a noise of some 20 G, and they have been
obtained at the disk center during the minimum of the solar cycle. The IN
regions show a typical unsigned flux density of the order of 15 G. Signals
occur, preferentially, in the intergranular lanes, and the strongest signals
trace a network with a scale similar to the mesogranulation. All these features
are consistent with the IN magnetograms by Dominguez Cernena et al., obtained
during the maximum of the solar cycle. Consequently, the unsigned magnetic flux
of the structures that give rise to the IN polarization signals does not seem
to undergo large variations during the solar cycle.


title:
Emission Line Properties of AGN from a post-COSTAR FOS HST Spectral
  Atlas

abstract:
  This paper joins a series compiling consistent emission line measurements of
large AGN spectral databases, useful for reliable statistical studies of
emission line properties. It is preceded by emission line measurements of 993
spectra from the Large Bright Quasar Survey (Forster et al. 2001) and 174
spectra of AGN obtained from the Faint Object Spectrograph (FOS) on HST prior
to the installation of COSTAR (Kuraszkiewicz et al. 2002). This time we
concentrate on 220 spectra obtained with the FOS after the installation of
COSTAR, completing the emission line analysis of all FOS archival spectra. We
use the same automated technique as in previous papers, which accounts for
Galactic extinction, models blended optical and UV iron emission, includes
Galactic and intrinsic absorption lines and models emission lines using
multiple Gaussians. We present UV and optical emission line parameters
(equivalent widths, fluxes, FWHM, line positions) for a large number (28) of
emission lines including upper limits for undetected lines. Further scientific
analyses will be presented in subsequent papers.


title:
Astrochemistry of Sub-Millimeter Sources in Orion: Studying the
  Variations of Molecular Tracers with Changing Physical Conditions

abstract:
  Cornerstone molecules (CO, H_2CO, CH_3OH, HCN, HNC, CN, CS, SO) were observed
toward seven sub-millimeter bright sources in the Orion molecular cloud in
order to quantify the range of conditions for which individual molecular line
tracers provide physical and chemical information. Five of the sources observed
were protostellar, ranging in energetics from 1 - 500L_sun, while the other two
sources were located at a shock front and within a photodissociation region
(PDR).
  Statistical equilibrium calculations were used to deduce from the measured
line strengths the physical conditions within each source and the abundance of
each molecule. In all cases except the shock and the PDR, the abundance of CO
with respect to H_2 appears significantly below (factor of ten) the general
molecular cloud value of 10^-4. {Formaldehyde measurements were used to
estimate a mean temperature and density for the gas in each source. Evidence
was found for trends between the derived abundance of CO, H_2CO, CH_3OH, and CS
and the energetics of the source, with hotter sources having higher
abundances.} Determining whether this is due to a linear progression of
abundance with temperature or sharp jumps at particular temperatures will
require more detailed modeling. The observed methanol transitions require high
temperatures (T>50 K), and thus energetic sources, within all but one of the
observed protostellar sources. The same conclusion is obtained from
observations of the CS 7-6 transition. Analysis of the HCN and HNC 4-3
transitions provides further support for high densities n> 10^7 cm^-3 in all
the protostellar sources.


title:
Limitations of the Hamiltonian Treatment for Collisionless Astrophysical
  Accretion Flows

abstract:
  In the Hamiltonian treatment of purely mechanical systems, the canonical and
actual momentum of a particle are the same. In contrast, for a plasma of
charged particles and electromagnetic fields, those two momenta are different.
We show how this distinction is fundamental in identifying the limitations of a
recent attempt by Binney (2003) to rule out two-temperature collisionless
astrophysical accretion flows from Hamiltonian theory. This illustrates the
Hamiltonian method for astrophysical plasmas, its relation to the equations of
motion, and its role in practical calculations. We also discuss how the
complete Hamiltonian treatment of a plasma should couple the particle motion to
a fully dynamical treatment of the electromagnetic fields. Our results stand
independent from the discussion of Quataert (2003) who argued that time scale
calculated in Binney (2003) is not the equipartition time as claimed.


title: Gamma Ray Bursts and Radio Loud Active Galactic Nuclei

abstract:
  We believe that the radiation we receive from Gamma-Ray Bursts (GRBs) and
radio loud Active Galacti Nuclei (AGNs) originates from the transformation of
bulk relativistic motion into random energy. Mechanisms to produce, collimate
and accelerates the jets in these sources are uncertain, and it may be fruitful
to compare the characteristics of both class of sources in search of
enlightening similarities. I will present some general characteristics of radio
loud AGNs and GRBs such as their bulk Lorentz factors and the power of their
jets. I will also discuss the way in which the energy in bulk relativistic
motion can be transformed into beamed radiation, and consider the possibility
that both classes of sources can work in the same way, namely by an
intermittent release of relativistic plasma at the base of the jet: shells
ejected with slightly different velocities collide at some distance from the
central engine, dissipating part of their kinetic energy, and keeping the rest
to power the extended radio lobes (in AGNs) or to produce the afterglow (in
GRBs).


title: Low-Mass Proto-Planet Migration in T-Tauri Alpha-Disks

abstract:
  We present detailed estimates of ''type-I'' migration rates for low-mass
proto-planets embedded in steady-state T-Tauri alpha-disks, based on Lindblad
torque calculations ignoring feedback on the disk. Differences in migration
rates for several plausible background disk models are explored and we contrast
results obtained using the standard two dimensional formalism of spiral density
wave theory with those obtained from a simple treatment of three-dimensional
effects. Opacity transitions in the disk result in sudden radial variations of
the migration rates. Regions with minimal migration rates may be preferred
sites of gravitational interactions between proto-planets. Three-dimensional
torques are significantly weaker than two-dimensional ones and they are
sensitive to the surface density profile of the background disk. We find that
migration times in excess of runaway envelope accretion times or T-Tauri disk
lifetimes are possible for Earth-mass proto-planets in some background disk
models, even at sub-AU distances. We conclude that an understanding of the
background disk structure and ''viscosity'', as well as a proper treatment of
three-dimensional effects in torque calculations, are necessary to obtain
reliable estimates of ``type-I'' migration rates.


title: A Subarcsecond Companion to the T Tauri Star AS 353B

abstract:
  Adaptive optics imaging of the bright visual T Tauri binary AS 353 with the
Subaru Telescope shows that it is a hierarchical triple system. The secondary
component, located 5.6" south of AS 353A, is resolved into a subarcsecond
binary, AS 353Ba and Bb, separated by 0.24". Resolved spectroscopy of the two
close components shows that both have nearly identical spectral types of about
M1.5. Whereas AS 353A and Ba show clear evidence for an infrared excess, AS
353Bb does not. We discuss the possible role of multiplicity in launching the
large Herbig-Haro flow associated with AS 353A.


title: Kinematics of Extremely Faint Dwarf Galaxies

abstract:
  We present the results of deep, high velocity resolution (~1.6 km/s) Giant
Meterwave Radio Telescope (GMRT) HI 21cm observations of extremely faint (M_B >
-12.5) dwarf irregular galaxies. We find that all of our sample galaxies show
systematic large scale velocity gradients, unlike earlier studies which found
chaotic velocity fields for such faint galaxies. For some of the sample
galaxies the velocity fields are completely consistent with ordered rotation,
though the peak circular velocities are comparable to the observed random
motions. These are the faintest known galaxies with such regular kinematics. We
present ("asymmetric drift" corrected) rotation curves and mass models
(including fits for Isothermal and NFW halos) for some of these galaxies and
discuss the implications for hierarchical models of galaxy formation.


title:
Supermassive fermion balls and constraints from stellar dynamics near
  Sgr A*

abstract:
  All presently known stellar-dynamical constraints on the size and mass of the
supermassive compact dark object at the Galactic center are consistent with a
ball of self-gravitating degenerate fermions with mass between 76 and 491 keV.
Sterile neutrinos of 76 keV mass, which are mixed with at least one of the
active neutrinos with a mixing angle ~10^{-7}, are produced in about the right
amount in the early Universe and may be responsible for the formation of the
supermassive degenerate fermion balls and black holes at the galactic centers.


title: Evidence for high accretion-rates in Weak-Line T Tauri stars?

abstract:
  We have discovered T Tauri stars which show startling spectral variability
between observations seperated by 20 years. In spectra published by Bouvier &
Appenzeller (1992) these objects showed very weak H-alpha emission, broad CaII
absorption and so called ``composite spectra'', where the spectral type
inferred from the blue region is earlier than that inferred from the red. We
present here new spectroscopy which shows that all four stars now exhibit
strong H-alpha emission, narrow CaII emission and a spectral type which is
consistent at all wavelengths.
  We propose a scheme to understand these changes whereby the composite spectra
of these stars can be explained by a period of active accretion onto the
central, young star. In this scheme the composite spectrum consists of a
contribution from the stellar photosphere and a contribution from a hot,
optically thick, accretion component. The optically thick nature of the
accretion flow explains the weakness of the H-alpha emission during this phase.
Within this scheme, the change to a single spectral type at all wavelengths and
emergence of strong H-alpha emission are consistent with the accretion columns
becoming optically thin, as the accretion rate drops. There is a strong analogy
here with the dwarf novae class of interacting binaries, which show similar
behaviour during the decline from outbursts of high mass-transfer rate.
  The most important consequence of this interpretation is that these objects
bring into question the association of Weak-Line T Tauri stars (WTTs) with
non-accreting or discless objects. In light of this result we consider the
justification for this paradigm.


title:
Weak lensing with COMBO-17: estimation and removal of intrinsic
  alignments

abstract:
  We estimate and remove the contamination of weak gravitational lensing
measurements by the intrinsic alignment of close pairs of galaxies. We do this
by investigating both the aperture mass B mode statistic, and the shear
correlations of close and distant pairs of galaxies. We re-analyse the COMBO-17
survey, and study published results from the RCS and the VIRMOS-DESCART survey,
concluding that the intrinsic alignment effect is at the lower end of the range
of theoretical predictions. We also revisit this theoretical issue, and show
that misalignment of baryon and halo angular momenta may be an important effect
which can reduce the intrinsic ellipticity correlations estimated from
numerical simulations to the level that we and the SuperCOSMOS survey observe.
We re-examine the cosmological parameter estimation from the COMBO-17 survey,
now marginalising over the Hubble constant. Assuming no evolution in galaxy
clustering, and marginalising over the intrinsic alignment signal, we find the
mass clustering amplitude is reduced by 0.03 to sigma_8(Omega_m / 0.27)^0.6 =
0.71 +/- 0.11. We consider the forthcoming SNAP wide weak lensing survey, and
the CFHTLS wide synoptic survey, and expect them to be contaminated on scales
>1 arcmin by intrinsic alignments at the level of ~1% and ~2% respectively.
Division of the SNAP survey for lensing tomography significantly increases the
contamination in the lowest redshift bin to ~7% and possibly higher. Removal of
the intrinsic alignment effect by the downweighting of nearby galaxy pairs will
therefore be vital for SNAP, (abridged).


title:
The X-ray Properties of Nearby Abell Clusters from the ROSAT All-Sky
  Survey: The Sample and Correlations with Optical Properties

abstract:
  We present an analysis of the X-ray emission for a complete sample of 288
Abell clusters spanning the redshift range 0.016<= z <= 0.09 from the ROSAT
All-Sky Survey. This sample is based on our 20cm VLA survey of nearby Abell
clusters. We find an X-ray detection rate of 83%. We report cluster X-ray
fluxes and luminosities and two different flux ratios indicative of the
concentration and extent of the emission. We examine correlations between the
X-ray luminosity, Abell Richness, and Bautz-Morgan and Rood-Sastry cluster
morphologies. We find a strong correlation between Lx and cluster richness
coupled to a dependence on the optical morphological type. These results are
consistent with the observed scatter between X-ray luminosity and temperature
and a large fraction of cooling flows. For each cluster field we also report
the positions, peak X-ray fluxes, and flux-ratios of all X-ray peaks above
3-sigma significance within a box of 2x2 Mpc centered on Abell's position.


title:
The Effect of Magnetic Field Tilt and Divergence on the Mass Flux and
  Flow Speed in a Line-Driven Stellar Wind

abstract:
  We carry out an extended analytic study of how the tilt and
faster-than-radial expansion from a magnetic field affect the mass flux and
flow speed of a line-driven stellar wind. A key motivation is to reconcile
results of numerical MHD simulations with previous analyses that had predicted
non-spherical expansion would lead to a strong speed enhancement. By including
finite-disk correction effects, a dynamically more consistent form for the
non-spherical expansion, and a moderate value of the line-driving power index
$\alpha$, we infer more modest speed enhancements that are in good quantitative
agreement with MHD simulations, and also are more consistent with observational
results. Our analysis also explains simulation results that show the
latitudinal variation of the surface mass flux scales with the square of the
cosine of the local tilt angle between the magnetic field and the radial
direction. Finally, we present a perturbation analysis of the effects of a
finite gas pressure on the wind mass loss rate and flow speed in both spherical
and magnetic wind models, showing that these scale with the ratio of the sound
speed to surface escape speed, $a/v_{esc}$, and are typically 10-20% compared
to an idealized, zero-gas-pressure model.


title: Out of the Chorus Line : What Makes 1E1207.4-5209 a Unique Object?

abstract:
  The discovery of deep spectral features in the X-ray spectrum of
1E1207.4-5209 has pushed this Isolated Neutron Star (INS) out of the chorus
line, since no other INS has shown significant features in its X-ray continuum.
On August 2002, XMM-Newton devoted a two-orbit TOO observation to this target
with the aim to better understand the nature of such spectral features, using
much improved statistics. Indeed, the 260 ksec observation yielded 360,000
photons from 1E1207.4-5209, allowing for a very sensitive study of the temporal
and spectral behaviour of this object.


title: A Simple Cosmological Model with Decreasing Light Speed

abstract:
  An alternative model describing the dynamics of a flat Universe without
cosmological constant and allowing a gradual change of c with time is proposed.
New relationships of redshift vs. distance and cosmic background radiation
temperature are given. Values for the Universal radius, matter density, Hubble
parameter, light deceleration, cosmic age and recombination time are obtained.
Distant SNeIa faintness is explained within this decelerating, matter-dominated
Universe without invoking dark energy. Horizon, flatness and other problems of
standard Big Bang cosmology are solved without the need of inflation. The top
speed of any signal, force, particle or wave at any time is limited by the
expansion speed of the Universe itself.


title: Magnetic Spin-Up of Line-Driven Winds

abstract:
  We summarize recent 2D MHD simulations of line-driven stellar winds from
rotating hot-stars with a dipole magnetic field aligned to the star's rotation
axis. For moderate to strong fields, much wind outflow is initially along
closed magnetic loops that nearly corotate as a solid body with the underlying
star, thus providing a torque that results in an effective angular momentum
spin-up of the outflowing material. But instead of forming the ``magnetically
torqued disk'' (MTD) postulated in previous phenemenological analyses, the
dynamical simulations here show that material trapped near the tops of such
closed loops tends either to fall back or break out, depending on whether it is
below or above the Keplerian corotation radius. Overall the results raise
serious questions about whether magnetic torquing of a wind outflow could
naturally result in a Keplerian circumstellar disk. However, for very strong
fields, it does still seem possible to form a %``magnetically confined,
centrifugally supported, rigid-body disk'', centrifugally supported,
``magnetically rigid disk'' (MRD), in which the field not only forces material
to maintain a rigid-body rotation, but for some extended period also holds it
down against the outward centrifugal force at the loop tops. We argue that such
rigid-body disks seem ill-suited to explain the disk emission from Be stars,
but could provide a quite attractive paradigm for circumstellar emission from
the magnetically strong Bp and Ap stars.


title: The Effects of Magnetic Fields on Line-Driven Hot-Star Winds

abstract:
  This talk summarizes results from recent MHD simulations of the role of a
dipole magnetic field in inducing large-scale structure in the line-driven
stellar winds of hot, luminous stars. Unlike previous fixed-field analyses, the
MHD simulations here take full account of the dynamical competition between the
field and the flow. A key result is that the overall degree to which the wind
is influenced by the field depends largely on a single, dimensionless `wind
magnetic confinement parameter', $\eta_\ast (= B_{eq}^2 R_{\ast}^2/\dot{M}
v_\infty$), which characterizes the ratio between magnetic field energy density
and kinetic energy density of the wind. For weak confinement, $\eta_\ast \le
1$, the field is fully opened by wind outflow, but nonetheless, for confinement
as small as $\eta_\ast=1/10$ it can have significant back-influence in
enhancing the density and reducing the flow speed near the magnetic equator.
For stronger confinement, $\eta_\ast > 1$, the magnetic field remains closed
over limited range of latitude and height above the equatorial surface, but
eventually is opened into nearly radial configuration at large radii. Within
the closed loops, the flow is channeled toward loop tops into shock collisions
that are strong enough to produce hard X-rays. Within the open field region,
the equatorial channeling leads to oblique shocks that are again strong enough
to produce X-rays and also lead to a thin, dense, slowly outflowing ``disk'' at
the magnetic equator.


title: Inhomogeneous Chaplygin Gas Cosmology

abstract:
  The hypothesis that dark matter and dark energy are unified through the
Chaplygin gas is reexamined. Using a generalization of the spherical model
which incorporates effects of the acoustic horizon we show that an initially
perturbative Chaplygin gas evolves into a mixed system containing cold dark
matter in the form of gravitational condensate. Furthermore, we demonstrate
that the observed CMB angular and baryonic power spectra are reproduced.


title: Cosmological dynamics of scalar field with non-minimal kinetic term

abstract:
  We investigate dynamics of scalar field with non-minimal kinetic term.
Nontrivial behavior of the field in the vicinity of singular points of kinetic
term is observed. In particular, the singular points could serve as attractor
for classical solutions.


title:
On the Divergence-Free Condition in Godunov-Type Schemes for Ideal
  Magnetohydrodynamics: the Upwind Constrained Transport Method

abstract:
  We present a general framework to design Godunov-type schemes for
multidimensional ideal magnetohydrodynamic (MHD) systems, having the
divergence-free relation and the related properties of the magnetic field B as
built-in conditions. Our approach mostly relies on the 'Constrained Transport'
(CT) discretization technique for the magnetic field components, originally
developed for the linear induction equation, which assures div(B)=0 and its
preservation in time to within machine accuracy in a finite-volume setting. We
show that the CT formalism, when fully exploited, can be used as a general
guideline to design the reconstruction procedures of the B vector field, to
adapt standard upwind procedures for the momentum and energy equations,
avoiding the onset of numerical monopoles of O(1) size, and to formulate
approximate Riemann solvers for the induction equation. This general framework
will be named here 'Upwind Constrained Transport' (UCT). To demonstrate the
versatility of our method, we apply it to a variety of schemes, which are
finally validated numerically and compared: a novel implementation for the MHD
case of the second order Roe-type positive scheme by Liu and Lax (J. Comp.
Fluid Dynam. 5, 133, 1996), and both the second and third order versions of a
central-type MHD scheme presented by Londrillo and Del Zanna (Astrophys. J.
530, 508, 2000), where the basic UCT strategies have been first outlined.


title: Dust and dark Gamma-Ray Bursts: mutual implications

abstract:
  In a cosmological context dust has been always poorly understood. That is
true also for the statistic of GRBs so that we started a program to understand
its role both in relation to GRBs and in function of z. This paper presents a
composite model in this direction. The model considers a rather generic
distribution of dust in a spiral galaxy and considers the effect of changing
some of the parameters characterizing the dust grains, size in particular. We
first simulated 500 GRBs distributed as the host galaxy mass distribution,
using as model the Milky Way. If we consider dust with the same properties as
that we observe in the Milky Way, we find that due to absorption we miss about
10% of the afterglows assuming we observe the event within about 1 hour or even
within 100s. In our second set of simulations we placed GRBs randomly inside
giants molecular clouds, considering different kinds of dust inside and outside
the host cloud and the effect of dust sublimation caused by the GRB inside the
clouds. In this case absorption is mainly due to the host cloud and the
physical properties of dust play a strong role. Computations from this model
agree with the hypothesis of host galaxies with extinction curve similar to
that of the Small Magellanic Cloud, whereas the host cloud could be also
characterized by dust with larger grains. To confirm our findings we need a set
of homogeneous infrared observations. The use of coming dedicated infrared
telescopes, like REM, will provide a wealth of cases of new afterglow
observations.


title: A Chandra View of the Multiple Merger In Abell 2744

abstract:
  We present a Chandra observation of the merging cluster of galaxies Abell
2744. The cluster shows strong evidence for an ongoing major merger which we
believe to be responsible for the radio halo. X-ray emission and temperature
maps of the cluster, combined with the spatial and redshift distribution of the
galaxies, indicate a roughly north-south axis for the merger, with a
significant velocity component along the line of sight. The merger is occurring
at a very large velocity, with M = 2-3. In addition, there is a small merging
subcluster toward the northwest, unrelated to the major merger, which shows
evidence of a bow shock. A hydrodynamical analysis of the subcluster indicates
a merger velocity corresponding to a Mach number of ~1.2, consistent with a
simple infall model. This infalling subcluster may also be re-exciting
electrons in the radio halo. Its small Mach number lends support to turbulent
reacceleration models for radio halo formation.


title: Cosmological parameters and the WMAP data

abstract:
  I discuss whether the standard cosmological models fit the WMAP data well
enough to justify parameter estimation with standard assumptions. The observed
quadrupole is low (but has significant foreground uncertainty) and drives weak
evidence for theoretical models predicting low values, such as models with a
running spectral index. Other more seriously outlying points of the WMAP power
spectrum appear not to fit the expectations of simple Gaussian models very
well. The effective temperature chi-squared is however acceptable on large
scales. There also appears to be evidence for an anisotropic distribution of
power, which taken together with the other points may indicate that either
there is a problem with the WMAP data or that standard cosmological models are
incorrect. These issues should be clarified before cosmological parameter
extraction for the usual standard models can be trusted, and hint that maybe
the CMB is more interesting than we imagined. I also discuss various systematic
and analysis issues, and comment on various oddities in the publicly available
first year WMAP data and code.


title: The Ofpe/WN9 stars in M33

abstract:
  We present HST/STIS Ultraviolet spectra of the six known Ofpe/WN9 stars
(``slash stars'') in M33. These stars were selected for showing the
characteristics of the Ofpe/WN9 class from previous optical ground-based
spectroscopy. The UV spectra are rich in wind lines, whose strength and
terminal velocity vary greatly among our target sample. We analyse the STIS
spectra with non-LTE, line blanketed, spherical models with hydrodynamics,
computed with the WM-basic code. We find C to be underabundant and N
overabundant, respect to the solar values, with a ratio (by mass) of C/N
between 0.02 to 0.9 across the sample. Some stars show very conspicuous wind
lines (P Cygni profiles), while two stars have extremely weak winds. The
mass-loss rates thus vary greatly across the sample.
  The mass-loss rates of the hottest stars are lower than typical values of WNL
stars, but higher than expected for normal population I massive stars. There is
indication that the mass-loss rates may be variable in time. The C/N ratio, and
the other physical parameters derived by the spectral modeling (Teff, Lbol,
mass), are consistent with evolutionary calculations for objects with
moderately high initial masses (approx 30-50 solar masses), evolving towards
the WNL stage through an enhanced mass-loss phase.


title:
MM-Newton Observations of two high redshift quasars: RX J1028-0844 and
  BR 0351-1034

abstract:
  We report the results of XMM-Newton observations of two high redshift
quasars, one radio-loud, RX J1028.6-0844 (z=4.276) and one radio-quiet, BR
0351-1034 (z=4.351). We find that the evidence for strong excess absorption
towards RX J1028-0844 is marginal at best, contrary to previous claims. The
superior sensitivity and broader, softer energy range of XMM-Newton (0.2-10
keV) allows better determination of spectral parameters than much deeper ASCA
observations (0.8-7 keV). Our XMM-Newton observations call into question
several other ASCA results of strong absorption towards high redshift
radio-loud quasars. RX J1028.6-0844 occupies the same parameter space in broad
band spectral properties as the low redshift BL Lac objects, showing no obvious
evolution with redshift. The radio-quiet quasar BR 0351-1024 became fainter
between ROSAT and XMM observations by a factor of at least 5, but with the
present data we cannot determine whether there is an associated spectral
change. These observations do not support previous claims of weaker X-ray
emission from high redshift radio-quiet quasars. The soft X-ray spectral slope
required to reconstruct the ROSAT PSPC hardness ratio of BR 0351-1034 is about
alpha-X=3.5, the steepest X-ray slope ever observed in a high redshift quasar,
and similar to that of low redshift Narrow Line Seyfert 1 galaxies.


title:
Galactic Evolution of Sr, Y, Zr: A Multiplicity of Nucleosynthetic
  Processes

abstract:
  We follow the Galactic enrichment of three easily observed light n-capture
elements Sr,Y,and Zr.Input stellar yields have been first separated into their
respective main and weak s-process,and r-process components.The s-process
yields from AGB stars are computed,exploring a wide range of efficiencies of
the major neutron source,13C,and covering both disk and halo metallicities.AGBs
have been shown to reproduce the main s-component in the solar system.The
concurrent weak s-process,which accounts for the major fraction of the light
s-process isotopes in the solar system and occurs in massive stars by the
operation of the 22Ne n-source,is discussed in detail.Neither the main s-,nor
the weak s-components are shown to contribute significantly to the n-capture
element abundances observed in unevolved halo stars.We present a detailed
analysis of a large database of spectroscopic observations of Sr,Y,Zr, Ba,and
Eu for Galactic stars at various metallicities.Spectroscopic observations of
Sr,Y,and Zr to Ba and Eu abundance ratios versus metallicity provide useful
diagnostics of the types of n-capture processes forming Sr,Y and Zr.The
observed [Sr,Y,Zr/Ba,Eu] ratio is clearly not flat at low metallicities,as we
would expect if Ba,Eu and Sr,Y,Zr all had the same r-process origin.We discuss
our chemical evolution predictions, taking into account the interplay between
different processes to produce Sr-Y-Zr.We find hints for a primary process in
low-metallicity massive stars, different from the 'classical s-process' and
from the 'classical r-process',that we tentatively define LEPP (Lighter Element
Primary Process).This allows us to revise the estimates of the r-process
contributions to the solar Sr,Y and Zr abundances,as well as of the
contribution to the s-only isotopes 86Sr,87Sr,96Mo.


title: A new sample of young Planetary Nebulae

abstract:
  Despite of numerous efforts, the stage from Asymptotic Giant Branch (AGB) to
Planetary Nebulae (PN) is a poorly understood phase of stellar evolution. We
have therefore carried out interferometric (VLA) observations of a sample of
hot post-AGB stars, selected on the basis of their optical and infrared
properties. Ten sources, out of the 16 been observed, were detected. This
indicates that most of our targets are surrounded by a nebula where the
ionization has already started. This definitively determines the evolutionary
status of the selected sources and provides us with a unique sample of very
young Planetary Nebulae (yPNs).


title: On the formation time scale and core masses of gas giant planets

abstract:
  Numerical simulations show that the migration of growing planetary cores may
be dominated by turbulent fluctuations in the protoplanetary disk, rather than
by any mean property of the flow. We quantify the impact of this stochastic
core migration on the formation time scale and core mass of giant planets at
the onset of runaway gas accretion. For standard Solar Nebula conditions, the
formation of Jupiter can be accelerated by almost an order of magnitude if the
growing core executes a random walk with an amplitude of a few tenths of an au.
A modestly reduced surface density of planetesimals allows Jupiter to form
within 10 Myr, with an initial core mass below 10 Earth masses, in better
agreement with observational constraints. For extrasolar planetary systems, the
results suggest that core accretion could form massive planets in disks with
lower metallicities, and shorter lifetimes, than the Solar Nebula.


title: Dark Matter in Dwarf Galaxies: The First Dark Galaxy?

abstract:
  We present new HI observations of the high-velocity cloud (HVC) that we
resolved near the Local Group dwarf galaxy LGS 3. The cloud is rotating, with
an implied mass that makes it dark matter-dominated no matter what its distance
from the Milky Way is. Our new, high-sensitivity Arecibo observations
demonstrate that the faint HI features that we previously described as tidal
tails are indeed real and do connect to the main body of the HVC. Thus, these
observations are consistent with our original hypothesis of a tidal interaction
between the HVC and LGS 3. We suggest that the HVC may be one of the missing
dark matter satellites in the Local Group that are seen in Cold Dark Matter
numerical simulations but have not yet been identified observationally.


title: Dark Matter in Dwarf Galaxies: Latest Density Profile Results

abstract:
  We present high-resolution two-dimensional velocity fields in Halpha and CO
of the nearby dwarf galaxy NGC 2976. Our observations were made at both higher
spatial resolution (~75 pc) and higher velocity resolution (13 km/s in Halpha
and 2 km/s in CO) than most previous studies. We show that NGC 2976 has a very
shallow dark matter density profile, with rho(r) lying between rho ~ r^-0.3 and
rho ~ r^0. We carefully test the effects of systematic uncertainties on our
results, and demonstrate that well-resolved, two-dimensional velocity data can
eliminate many of the systematic problems that beset longslit observations. We
also present a preliminary analysis of the velocity field of NGC 5963, which
appears to have a nearly NFW density profile.


title: The Destruction of Bars by Central Mass Concentrations

abstract:
  More than two thirds of disk galaxies are barred to some degree. Many today
harbor massive concentrations of gas in their centers, and some are known to
possess supermassive black holes (SMBHs) and their associated stellar cusps.
Previous theoretical work has suggested that a bar in a galaxy could be
dissolved by the formation of a mass concentration in the center, although the
precise mass and degree of central concentration required is not
well-established. We report an extensive study of the effects of central masses
on bars in high-quality N-body simulations of galaxies. We have varied the
growth rate of the central mass, its final mass and degree of concentration to
examine how these factors affect the evolution of the bar. Our main conclusions
are: (1) Bars are more robust than previously thought. The central mass has to
be as large as several percent of the disk mass to completely destroy the bar
on a short timescale. (2) For a given mass, dense objects cause the greatest
reduction in bar amplitude, while significantly more diffuse objects have a
lesser effect. (3) The bar amplitude always decreases as the central mass is
grown, and continues to decay thereafter on a cosmological time-scale. (4) The
first phase of bar-weakening is due to the destruction by the CMC of
lower-energy, bar-supporting orbits, while the second phase is a consequence of
secular changes to the global potential which further diminish the number of
bar-supporting orbits. We provide detailed phase-space and orbit analysis to
support this suggestion. Thus current masses of SMBHs are probably too small,
even when dressed with a stellar cusp, to affect the bar in their host
galaxies. The molecular gas concentrations found in some barred galaxies are
also too diffuse to affect the amplitude of the bar significantly.


title: Interaction of the AGN and X-ray Emitting Gas

abstract:
  The process that prevents the deposition of cooled gas in cooling flows must
rely on feedback in order to maintain gas with short cooling times, while
preventing the bulk of the gas from cooling to low temperatures. The primary
candidate for the feedback mechanism is the accretion of cooled and cooling gas
by an active galactic nucleus (AGN). Despite some difficulties with this model,
the high incidence of central radio sources in cooling flows and the common
occurrence of radio lobe cavities, together, support this view. The Bondi
accretion rate for the intracluster gas onto the AGN depends on the gas
properties only through its specific entropy and that is governed directly by
competition between heating and cooling. This provides a viable link for the
feedback process. It is argued that the mass accreted between outbursts by the
central AGN is only sensitive to the mass of the black hole and the gas
temperature. Bondi accretion by an AGN leads to a simple expression for
outburst energy that can be tested against observations.


title: Environmental Effects on Galaxy Evolution

abstract:
  It is a remarkable feature that various properties of galaxies vary according
to their environments. However, only little has been known on the origin of
this variety in galaxies. Using the Sloan Digital Sky Survey (SDSS) data, we
investigate the morphology-density relation to find two characteristic
environment where the morphology-density relation abruptly changes (0.3 and 2
Rvir).The result has significant implication for the underlying physical
mechanism since it suggests that two different mechanisms might be responsible
for the morphology-density relation. In addition, we study the environment of
unusual spiral galaxies with no [OII] or Halpha emission lines (passive
spirals), and find that passive spiral galaxies preferentially live in cluster
infalling regions (1-10 Rvir}). Thus, the origin of passive spiral galaxies is
likely to be cluster related. Based on all of our observational results, we
propose possible fate of cluster infalling galaxies.


title:
The Asymptotic Giant Branch of NGC 205: The Characteristics of Carbon
  Stars and M Giants Identified from JHK' Images

abstract:
  J, H, and K' images are used to investigate the asymptotic giant branch (AGB)
content of the Local Group dwarf elliptical galaxy NGC 205. The AGB on the (K,
H-K) and (K, J-K) color-magnitude diagrams consists of two sequences: a
near-vertical plume of giants with spectral types K and M, and a red arm
containing C stars. There are 320 C stars with M_bol < -4.1 and J-K > 1.5
within 2 arcmin of the nucleus. C stars account for 10% of the integrated
luminosity of AGB stars brighter than M_bol = -3.75 near the center of NGC 205,
and this is in excellent agreement with what is measured in intermediate-age
clusters in the LMC. The most luminous AGB star has M_bol = -6.5, although
variability introduces an uncertainty of a few tenths of a magnitude when using
this as an estimate of the AGB-tip brightness. Comparisons with models suggest
that the brightest AGB stars formed within the past 0.1 Gyr, and that the
previous episode of star formation occured a few tenths of a Gyr earlier. These
results are consistent with star formation in NGC 205 being triggered by
interactions with M31. These data also demonstrate that near-infrared imaging
provides an efficient means of identifying C stars in nearby galaxies.


title:
Signatures of Relativistic Neutrinos in CMB Anisotropy and Matter
  Clustering

abstract:
  We present a detailed analytical study of ultra-relativistic neutrinos in
cosmological perturbation theory and of the observable signatures of
inhomogeneities in the cosmic neutrino background. We note that a modification
of perturbation variables that removes all the time derivatives of scalar
gravitational potentials from the dynamical equations simplifies their solution
notably. The used perturbations of particle number per coordinate, not proper,
volume are generally constant on superhorizon scales. In real space an
analytical analysis can be extended beyond fluids to neutrinos.
  The faster cosmological expansion due to the neutrino background changes the
acoustic and damping angular scales of the cosmic microwave background (CMB).
But we find that equivalent changes can be produced by varying other standard
parameters, including the primordial helium abundance. The low-l integrated
Sachs-Wolfe effect is also not sensitive to neutrinos. However, the gravity of
neutrino perturbations suppresses the CMB acoustic peaks for the multipoles
with l>~200 while it enhances the amplitude of matter fluctuations on these
scales. In addition, the perturbations of relativistic neutrinos generate a
*unique phase shift* of the CMB acoustic oscillations that for adiabatic
initial conditions cannot be caused by any other standard physics. The origin
of the shift is traced to neutrino free-streaming velocity exceeding the sound
speed of the photon-baryon plasma. We find that from a high resolution, low
noise instrument such as CMBPOL the effective number of light neutrino species
can be determined with an accuracy of sigma(N_nu) = 0.05 to 0.09, depending on
the constraints on the helium abundance.


title: Coupling between satellite dwarfs and the Milky Way warp

abstract:
  The perturbations of satellite galaxies, in particular the Large Magellanic
Cloud (LMC), have been repeatedly proposed and discounted as the cause of the
Milky Way warp. While the LMC may excite a wake in the Galactic dark matter
halo that could provide sufficient torque to excite a warp of the observed
magnitude, its orbit may be incompatible with the orientation of the warp's
line of nodes. The Sgr dSph galaxy has an appropriately-oriented orbit, and due
to its closer orbit may produce a stronger tidal effect than the LMC. Evidence
that Sgr may be responsible for the warp comes from its orbital angular
momentum, which has the same magnitude as the angular momentum of the warped
component of the Galactic disk and is anti-aligned with it. We have run high
resolution numerical N-body simulations of Sgr-sized satellites around a Milky
Way-sized disk to test this idea. Preliminary results suggest that Sgr-sized
satellites can indeed excite warps with properties similar to that observed for
the Milky Way.


title: X-Ray Binary Populations: The Luminosity Function of NGC1569

abstract:
  Using the population synthesis code StarTrack we construct the first
synthetic X-ray binary populations for direct comparison with the X-ray
luminosity function (XLF) of NGC 1569 observed with Chandra.
  Our main goal is to examine whether it is possible to reproduce the XLF shape
with our models, given the current knowledge for the star-formation history of
this starburst galaxy. We thus produce hybrid models meant to represent the two
stellar populations: one old, metal-poor with continuous star-formation for 1.5
Gyr and another recent and metal-rich population. To examine the validity of
the models we compare XLFs calculated for varying ages of the populations and
varying relative weights for the star-formation rates in the two populations.
  We find that, for typical binary evolution parameters, it is indeed possible
to quite closely match the observed XLF shape.
  The robust match is achieved for an age of the young population and a ratio
of star formation rates in the two populations that are within factors of 1.5
and 2, respectively, of those inferred from HST observations of NGC 1569.
  In view of this encouraging first step, we discuss the implications of our
X-ray binary models and their potential as tools to study binary populations in
galaxies.


title: Pulsar Birthrate from Parkes Multi-beam Survey

abstract:
  We report on calculations of the pulsar birthrate based on the results of the
Parkes multibeam survey. From the observed sample of more than 800 pulsars, we
compute the pulsar current, accounting as accurately as possible for all known
selection effects. The main goal of this work is to understand the pulsar
birthrate as a function of the surface dipole magnetic field strengths. We show
that pulsars with magnetic fields greater than 10**12.5 G account for about
half of the total birthrate.


title: A Phenomenological Model for the Evolution of Proto-Galaxies

abstract:
  The contraction model of Field and Colgate for proto-galaxies, first proposed
to describe the observed properties of quasars, is generalized and used to
investigate the evolution of galaxies. The LEDA data base for elliptical,
spiral, compact and diffuse galaxies is employed and it is shown that the above
model is consistent with observational evidences regarding their dynamical
evolution, star formation rate and different morphologies.


title: X-ray Cluster Properties in SPH Simulations of Galaxy Clusters

abstract:
  Results from a large set of hydrodynamical SPH simulations of galaxy clusters
in a flat LCDM cosmology are used to investigate cluster X-ray properties. The
physical modeling of the gas includes radiative cooling, star formation, energy
feedback and metal enrichment that follows from the explosions of SNe type II
and Ia. The metallicity dependence of the cooling function is also taken into
account. It is found that the luminosity-temperature relation of simulated
clusters is in good agreement with the data, and the X-ray properties of cool
clusters are unaffected by the amount of feedback energy that has heated the
intracluster medium (ICM). The fraction of hot gas $f_g$ at the virial radius
increases with $T_X$ and the distribution obtained from the simulated cluster
sample is consistent with the observational ranges.


title: Kinematics of the dwarf irregular galaxy GR8

abstract:
  We present deep, high velocity resolution (~1.6 km/s) Giant Meterwave Radio
Telescope HI 21cm synthesis images for the faint (M_B ~ -12.1) dwarf irregular
galaxy GR8. We find that the velocity field of the galaxy shows a clear
systematic large scale pattern, with a maximum amplitude ~10 km/s. Neither pure
rotation, nor pure radial motion alone can fit the observed velocity field;
however a combination of radial and circular motions can provide a reasonable
fit. The most natural interpretation is that the neutral ISM, in addition to
rotating about the center, is also expanding outwards, as a result of energy
input from the ongoing star formation in the galaxy. Support for this
interpretation comes from the fact that the pressure in the HII regions in the
galaxy is known to be substantially (~55 times) more than the average pressure
in the gas disk. It is, however, also possible that the velocity field is the
result of the gas swirling inwards, in which case GR8 could be in the process
of formation via the merger of subgalactic clumps.


title:
Accretion of dust grains as a possible origin of metal-poor stars with
  low alpha/Fe ratios

abstract:
  The origin of low alpha/Fe ratios in some metal-poor stars, so called
low-alpha stars, is discussed. It is found that most of low-alpha stars in the
Galaxy are on the main-sequence. This strongly suggests that these stars
suffered from external pollution. It is also found that the abundance ratios
Zn/Fe of low-alpha stars both in the Galaxy and in dwarf spheroidal galaxies
are lower than the average value of Galactic halo stars whereas damped Ly alpha
absorbers have higher ratios. This implies that some low-alpha stars accreted
matter depleted from gas onto dust grains. To explain the features in these
low-alpha stars, we have proposed that metal-poor stars harboring planetary
systems are the origin of these low-alpha stars. Stars engulfing a small
fraction of planetesimals enhance the surface content of Fe to exhibit low
alpha/Fe ratios on their surfaces while they are on the main-sequence, because
dwarfs have shallow surface convection zones where the engulfed matter is
mixed. After the stars leave the main-sequence, the surface convection zones
become deeper to reduce the enhancement of Fe. Eventually, when the stars
ascend to the tip of the red giant branch, they engulf giant planets to become
low-alpha stars again as observed in dwarf spheroidal galaxies. We predict that
low-alpha stars with low Mn/Fe ratios harbor planetary systems.


title:
Correlated adiabatic and isocurvature CMB fluctuations in the light of
  the WMAP data

abstract:
  In multi-field inflation models, correlated adiabatic and isocurvature
fluctuations are produced and in addition to the usual adiabatic fluctuation
with a spectral index n_ad1 there is another adiabatic component with a
spectral index n_ad2 generated by entropy perturbation during inflation, if the
trajectory in the field space is curved. Allowing n_ad1 and n_ad2 to vary
independently we find that the WMAP data favour models where the two adiabatic
components have opposite spectral tilts. This leads naturally to a running
adiabatic spectral index. The WMAP data with a prior n_iso < 1.84 for the
isocurvature spectral index gives fiso < 0.84 for the isocurvature fraction of
the initial power spectrum at k_0 = 0.05 Mpc^{-1}. We also comment on a
degeneration between the correlation component and the optical depth tau.
Moreover, the measured low quadrupole in the TT angular power could be achieved
by a strong negative correlation, but then one would need a large tau to fit
the TE spectrum.


title: A Maximum Likelihood Analysis of the Low CMB Multipoles from WMAP

abstract:
  The amplitudes of the quadrupole and octopole measured from the Wilkinson
Microwave Anisotropy Probe (WMAP) appear to be lower than expected according to
the concordance Lambda CDM cosmology. However, the pseudo-Cl estimator used by
the WMAP team is non-optimal. In this paper, we discuss the effects of Galactic
cuts on pseudo-Cl and quadratic maximum likelihood estimators. An application
of a quadratic maximum likelihood estimator to Galaxy subtracted maps produced
by the WMAP team and Tegmark, de Oliveira-Costa and Hamilton (2003) shows that
the amplitudes of the low multipoles are stable to different Galactic cuts. In
particular, the quadrupole and octopole amplitudes are found to lie in the
ranges 176 - 250 (micro K)**2 794 - 1183 (micro K)**2 (and more likely to be at
the upper ends of these ranges) rather than the values of 123 (micro K)**2 and
611 (micro K)**2 found by the WMAP team. These results indicate that the
discrepancy with the concordance Lambda CDM model at low multipoles is not
particularly significant and is in the region of a few percent. This conclusion
is consistent with an analysis of the low amplitude of the angular correlation
function computed from quadratic maximum likelihood power spectrum estimates.


title: Radiative constraints on brane quintessence

abstract:
  We investigate the constraints on quintessence arising from both
renormalisable and non-renormalisable couplings where the 5d Planck mass is
around the TeV scale. The quintessence field vacuum expectation value is
typically of order the 4d Planck mass while non-renormalisable operators are
expected to be suppressed by the 5d Planck mass. Non-renormalisable operators
are therefore important in computing the 4d effective quintessence potential.
We then study the quantum corrections to the quintessence potential due to
fermion and graviton loops. The tower of Kaluza-Klein modes competes with the
TeV-scale cut-off, altering the graviton contribution to the vacuum
polarization of quintessence. Nevertheless we show that, as in four dimensions,
the classical potential is stable to such radiative corrections.


title:
Variable Star Network: World Center for Transient Object Astronomy and
  Variable Stars

abstract:
  Variable Star Network (VSNET, http://www.kusastro.kyoto-u.ac.jp/vsnet/) is a
global professional-amateur network of researchers in variable stars and
related objects, particularly in transient objects, such as cataclysmic
variables, black hole binaries, supernovae and gamma-ray bursts. The VSNET has
been playing a pioneering role in establishing the field of "transient object
astronomy", by effectively incorporating modern advance in observational
astronomy and global electronic network, as well as collaborative progress in
theoretical astronomy and astronomical computing. The VSNET is now one of the
best-featured global networks in this field of astronomy. We review on the
historical progress, design concept, associated technology, and a wealth of
scientific achievements powered by the VSNET.


title: The Infrared Supernova Rate

abstract:
  Optical searches can only detect supernovae with a limited amount of dust
extinction. This is a severe limitation as most of the core-collapse SNe could
explode inside dusty regions. We describe a few ongoing projects aimed at
detecting dusty SNe at near-IR wavelengths both in ground-based and HST images
and to study their properties.


title: The Merging History of Massive Black Holes

abstract:
  We investigate a hierarchical structure formation scenario describing the
evolution of a Super Massive Black Holes (SMBHs) population. The seeds of the
local SMBHs are assumed to be 'pregalactic' black holes, remnants of the first
POPIII stars. As these pregalactic holes become incorporated through a series
of mergers into larger and larger halos, they sink to the center owing to
dynamical friction, accrete a fraction of the gas in the merger remnant to
become supermassive, form a binary system, and eventually coalesce. A simple
model in which the damage done to a stellar cusps by decaying BH pairs is
cumulative is able to reproduce the observed scaling relation between galaxy
luminosity and core size. An accretion model connecting quasar activity with
major mergers and the observed BH mass-velocity dispersion correlation
reproduces remarkably well the observed luminosity function of
optically-selected quasars in the redshift range 1<z<5. We finally asses the
potential observability of the gravitational wave background generated by the
cosmic evolution of SMBH binaries by the planned space-born interferometer
LISA.


title:
The Halpha Luminosity Function of the Galaxy Cluster Abell 521 at z =
  0.25

abstract:
  We present an optical multicolor-imaging study of the galaxy cluster Abell
521 at $z = 0.25$, using Suprime-Cam on the Subaru Telescope, covering an area
of $32 \times 20$ arcmin$^2$ ($9.4 \times 5.8 h_{50}^{-2}$ Mpc$^2$ at $z =
0.25$). Our imaging data taken with both a narrow-band filter, $NB816$
($\lambda_0 = 8150$\AA and $\Delta \lambda = 120$\AA), and broad-band filters,
$B,V,R_{\rm C}, i^\prime$, and $z^\prime$ allow us to find 165 H$\alpha$
emitters. We obtain the H$\alpha$ luminosity function (LF) for the cluster
galaxies within 2 Mpc; the Schechter parameters are $\alpha = -0.75 \pm 0.23$,
$\phi^\star = 10^{-0.25 \pm 0.20}$ Mpc$^{-3}$, and $L^\star = 10^{42.03 \pm
0.17}$ erg s$^{-1}$. Although the faint end slope, $\alpha$, is consistent with
that of the local cluster H$\alpha$ LFs, the characteristic luminosity,
$L^\star$, is about 6 times (or $\approx 2$ mag) brighter. This strong
evolution implies that Abell 521 contains more active star-forming galaxies
than the local clusters, being consistent with the observed Butcher-Oemler
effect. However, the bright $L^\star$ of Abell 521 may be, at least in part,
due to the dynamical condition of this cluster.


title:
Binary black holes in Mkns as sources of gravitational radiation for
  space based interferometers

abstract:
  The possibility that some Markarian objects (e.g. Mkn 501, Mkn 421 and Mkn
766) host massive binary black hole systems with eccentric orbits at their
centers has been considered. These systems could be sources of gravitational
radiation for space-based gravitational wave interferometers like LISA and
ASTROD. In the framework of the Lincoln -- Will approximation we simulate
coalescence of such systems, calculate gravitational wave templates and discuss
parameters of these binary black hole systems corresponding to the facilities
of LISA and ASTROD. We discuss also the possibility to extract information
about parameters of the binary black hole systems (masses, of components,
distances between them, eccentricity and orbit inclination angle with respect
to line of sight) from future gravitational wave measurements.


title:
Observational Cosmology: caveats and open questions in the standard
  model

abstract:
  I will review some results of observational cosmology which critically cast
doubt upon the foundations of the standard cosmology: 1) The redshifts of the
galaxies are due to the expansion of the Universe; 2) The cosmic microwave
background radiation and its anisotropies come from the high energy primordial
Universe; 3) The abundance pattern of the light elements is to be explained in
terms of the primordial nucleosynthesis; 4) The formation and evolution of
galaxies can only be explained in terms of gravitation in the cold dark matter
theory of an expanding Universe. The review does not pretend to argue against
this standard scenario in favour of an alternative theory, but to claim that
cosmology is still a very young science and should leave the door wide open to
other positions.


title: WIMP direct detection and halo structure

abstract:
  Weakly Interacting Massive Particle (WIMP) direct detection experiments are
just reaching the sensitivity required to detect Galactic dark matter in the
form of neutralinos (or indeed any stable weakly interacting particle).
Detection strategies and data analyses are often based on the simplifying
assumption of a standard spherical, isothermal halo model, but observations and
numerical simulations indicate that galaxy halos are in fact triaxial and
anisotropic, and contain substructure. The annual modulation and direction
dependence of the event rate (due to the motion of the Earth) provide the best
prospects of distinguishing WIMP scattering from background events, however
these signals depend sensitively on the local WIMP velocity distribution. I
briefly review the status of WIMP direct detection experiments before
discussing the dependence of the annual modulation signal on astrophysical
input, in particular the structure of the Milky Way halo, and the possibility
that the local WIMP distribution is not smooth.


title: Grain Size Distributions and Photo-Electric Heating in Ionized Regions

abstract:
  In this paper we present results obtained with the new grain code in Cloudy
which underline the strong effect of photo-electric heating by grains in
photo-ionized regions. We study the effect that the distribution of grain sizes
has on the magnitude of the effect, and show that this effect is nothing short
of dramatic. This makes the grain size distribution an important parameter in
modeling of photo-ionized regions such as H II regions and planetary nebulae.


title:
Determining the Metallicity of Cepheid Stars in the SMC, LMC and the
  Galaxy

abstract:
  The Cepheid Period-Luminosity relation is unquestionably one of the most
powerful tools at our disposal for determining the extragalactic distance
scale. While significant progress has been made in the past few years towards
its understanding and characterisation, both on the observational (e.g. the HST
Key Project) and theoretical (e.g. non-linear pulsation models, non-LTE
atmospheres etc.) sides, the debate on the influence that chemical composition
may have on the Period-Luminosity relation is still unsettled. Current
estimates lead to differences in the distance as large as 15%, effectively
limiting the accuracy of Cepheids as distance indicators.
  To further tackle this problem, we have obtained high resolution spectra of a
large sample of Cepheids in our Galaxy and the Magellanic Clouds. The superb
quality of the data allow us to probe the detailed effects of chemical
composition (alpha, iron-group, and heavy elements) over more than a factor of
ten in metallicity. Here, we present the first preliminary results of the
analysis of iron abundances in a sub-sample of Cepheids.


title: Tidal dissipation in rotating giant planets

abstract:
  [Abridged] Tides may play an important role in determining the observed
distributions of mass, orbital period, and eccentricity of the extrasolar
planets. In addition, tidal interactions between giant planets in the solar
system and their moons are thought to be responsible for the orbital migration
of the satellites, leading to their capture into resonant configurations. We
treat the underlying fluid dynamical problem with the aim of determining the
efficiency of tidal dissipation in gaseous giant planets. In cases of interest,
the tidal forcing frequencies are comparable to the spin frequency of the
planet but small compared to its dynamical frequency. We therefore study the
linearized response of a slowly and possibly differentially rotating planet to
low-frequency tidal forcing. Convective regions of the planet support inertial
waves, while any radiative regions support generalized Hough waves. We present
illustrative numerical calculations of the tidal dissipation rate and argue
that inertial waves provide a natural avenue for efficient tidal dissipation in
most cases of interest. The resulting value of Q depends in a highly erratic
way on the forcing frequency, but we provide evidence that the relevant
frequency-averaged dissipation rate may be asymptotically independent of the
viscosity in the limit of small Ekman number. In short-period extrasolar
planets, if the stellar irradiation of the planet leads to the formation of a
radiative outer layer that supports generalized Hough modes, the tidal
dissipation rate can be enhanced through the excitation and damping of these
waves. These dissipative mechanisms offer a promising explanation of the
historical evolution and current state of the Galilean satellites as well as
the observed circularization of the orbits of short-period extrasolar planets.


title: Dark Matter in Galaxies: Conference Summary

abstract:
  The competition between CDM and MOND to account for the `missing mass'
phenomena is asymmetric. MOND has clearly demonstrated that a characteristic
acceleration $a_0$ underlies the data and understanding what gives rise to
$a_0$ is an important task. The reason for MOND's success may lie in either the
details of galaxy formation, or an advance in fundamental physics that reduces
to MOND in a suitable limit. CDM has enjoyed great success on large scales. The
theory cannot be definitively tested on small scales until galaxy formation has
been understood because baryons either are, or possibly have been, dominant in
all small-scale objects. MOND's predictive power is seriously undermined by its
isolation from the rest of physics. In view of this isolation, the way forward
is probably to treat CDM as an established theory to be used alongside
relativity and electromagnetism in efforts to understand the formation and
evolution of galaxies.


title: Revised positions for the CIG galaxies

abstract:
  We present revised positions for the 1051 galaxies belonging to the
Karachentseva Catalog of Isolated Galaxies (CIG). New positions were calculated
by applying SExtractor to the Digitized Sky Survey CIG fields with a spatial
resolution of 1.2''. We visually checked the results and for 118 galaxies had
to recompute the assigned positions due to complex morphologies (e.g. distorted
isophotes, undefined nuclei, knotty galaxies) or the presence of bright stars.
We found differences between older and newer positions of up to 38'' with a
mean value of 2.96'' relative to SIMBAD and up to 38'' and 2.42'' respectively
relative to UZC. Based on star positions from the APM catalog we determined
that the DSS astrometry of five CIG fields has a mean offset in (RA, Dec) of
(-0.90'',0.93'') with a dispersion of 0.4''. These results have been confirmed
using the 2MASS All-Sky Catalog of Point Sources. The intrinsic errors of our
method combined with the astrometric ones are of the order of 0.5''.


title:
The Sizes and Kinematic Structure of Absorption Systems Towards the
  Lensed Quasar APM08279+5255

abstract:
  We have obtained spatially resolved spectra of the z=3.911 triply imaged QSO
APM08279+5255 using the Space Telescope Imaging Spectrograph (STIS) on board
the Hubble Space Telescope (HST). We study the line of sight equivalent width
(EW) differences and velocity shear of high and low ionization absorbers
(including a damped Lyman alpha [DLA] system identified in a spatially
unresolved ground based spectrum) in the three lines of sight. We find that
high ionization systems (primarily CIV absorbers) do not exhibit strong EW
variations on scales <0.4 kpc; their fractional EW differences are typically
less than 30%. When combined with previous work on other QSO pairs, we find
that the fractional variation increases steadily with separation out to at
least ~100 kpc. Conversely, low ionization systems (primarily MgII absorbers)
show strong variations (often > 80%) over kpc scales. A minimum radius for
strong (EW > 0.3 A) MgII systems of > 1.4 kpc is inferred from absorption
coincidences in all lines of sight. For weak MgII absorbers (EW < 0.3 A), a
maximum likelihood analysis indicates a most probable coherence scale of 2.0
kpc for a uniform spherical geometry, with 95% confidence limits ranging
between 1.5 and 4.4 kpc. Finally, for systems with weak absorption that can be
confidently converted to column densities, we find constant N(CIV)/N(SiIV)
across the three lines of sight. Similarly, the [Al/Fe] ratios in the z = 2.974
DLA are consistent with solar relative abundances over a transverse distance of
\~0.35 kpc. (abrdiged)


title: Cooling Flows or Heating Flows?

abstract:
  It is now clear that AGN heat cooling flows, largely by driving winds. The
winds may contain a relativistic component that generates powerful synchrotron
radiation, but it is not clear that all winds do so. The spatial and temporal
stability of the AGN/cooling flow interaction are discussed. Collimation of the
winds probably provides spatial stability. Temporal stability may be possible
only for black holes with masses above a critical value. Both the failure of
cooling flows to have adiabatic cores and the existence of X-ray cavities
confirm the importance of collimated outflows. I quantify the scale of the
convective flow that the AGN Hydra would need to drive if it balanced radiative
inward flow by outward flow parallel to the jets. At least in Virgo any such
flow must be confined to r<~20 kpc. Hydrodynamical simulations suggest that AGN
outbursts cannot last longer than ~25 Myr. Data for four clusters with well
studied X-ray cavities suggests that heating associated with cavity formation
approximately balances radiative cooling. The role of cosmic infall and the
mechanism of filament formation are briefly touched on.


title: Early reionization by miniquasars

abstract:
  Motivated by the recent detection by WMAP of a large optical depth to Thomson
scattering -- implying a very early reionization epoch -- we assess a scenario
where the universe was reionized by `miniquasars' powered by intermediate-mass
black holes (IMBHs), the remnants of the first generation of massive stars.
Pregalactic IMBHs form within minihalos above the cosmological Jeans mass
collapsing at z=24, get incorporated through mergers into larger and larger
systems, sink to the center owing to dynamical friction, and accrete cold
material. The merger history of dark halos and associated IMBHs is followed by
Monte Carlo realizations of the merger hierarchy in a LCDM cosmology. While
seed IMBHs that are as rare as the 3.5-sigma peaks of the primordial density
field evolve largely in isolation, a significant number of black hole binary
systems will form if IMBHs populate the more numerous 3-sigma peaks instead. In
the case of rapid binary coalescence a fraction of IMBHs will be displaced from
galaxy centers and ejected into the IGM by the `gravitational rocket' effect,
rather than accrete and shine as miniquasars. We show that, under a number of
plausible assumptions for the amount of gas accreted onto IMBHs and their
emission spectrum, miniquasars powered by IMBHs may be responsible for
cosmological reionization at z~15. Reionization by miniquasars with a hard
spectrum may be more `economical' than stellar reionization, as soft X-rays
escape more easily from the dense sites of star formation and travel further
than EUV radiation. Energetic photons will make the diffuse IGM warm and weakly
ionized prior to the epoch of reionization breakthrough, set an entropy floor,
and reduce gas clumping. Future 21 cm observations may detect a preheated,
weakly-ionized IGM in emission against the CMB. (abridged)


title: Accretion Onto Fast X-Ray Pulsars

abstract:
  The recent emergence of a new class of accretion-powered, transient,
millisecond X-ray pulsars presents some difficulties for the conventional
picture of accretion onto rapidly rotating magnetized neutron stars and their
spin behavior during outbursts. In particular, it is unclear from the standard
paradigm how these systems manage to accrete over such a wide range in dM/dt
(i.e., >~ a factor of 50), and why the neutron stars exhibit a high rate of
spindown in at least a number of cases. Following up on prior suggestions, we
propose that `fast' X-ray pulsars can continue to accrete, and that their
accretion disks terminate at approximately the corotation radius. We
demonstrate the existence of such disk solutions by modifying the
Shakura-Sunyaev equations with a simple magnetic torque prescription. The
solutions are completely analytic, and have the same dependence on dM/dt and
alpha (the viscosity parameter) as the original Shakura-Sunyaev solutions; but,
the radial profiles can be considerably modified, depending on the degree of
fastness. We apply these results to compute the torques expected during the
outbursts of the transient millisecond pulsars, and find that we can explain
the large spindown rates that are observed for quite plausible surface magnetic
fields of ~10^9 G.


title: First observations of the X-ray transient EXO 2030+375 with IBIS/ISGRI

abstract:
  We present a first INTEGRAL observation of the 42s transient X-ray pulsar EXO
2030+375 with IBIS/ISGRI. The source was detected during Cyg X-1 observations
in December 2002. We analyzed observations during the outburst period from 9 to
21 December 2002 with a total exposure time of ~770 kiloseconds. EXO 2030+375
was almost always detected during single ~30 minute exposures in the 18-45
energy bands. The source light curve shows the characteristic outburst shape
observed in this source.


title: X-Ray Spectral Variability of Extreme BL Lac AGN H1426+428

abstract:
  Between 7 March 2002 and 15 June 2002, intensive X-ray observations were
carried out on the extreme BL Lac object H1426+428 with instruments on board
the Rossi X-ray Timing Explorer (RXTE). These instruments provide measurements
of H1426+428 in the crucial energy range that characterizes the first peak of
its spectral energy distribution. This peak, which is almost certainly due to
synchrotron emission, has previously been inferred to be in excess of 100 keV.
By taking frequent observations over a four-month campaign, which included
$\sim$450 ksec of RXTE time, studies of flux and spectral variability on
multiple timescales were performed, along with studies of spectral hysteresis.
The 3-24 keV X-ray flux and spectra exhibited significant variability, implying
variability in the location of the first peak of the spectral energy
distribution. Hysteresis patterns were observed, and their characteristics have
been discussed within the context of emission models.


title: Evolution of the Inner Circumstellar Envelope of V838 Monocerotis

abstract:
  We present imaging polarimetry observations of the eruptive variable V838
Monocerotis and its neighboring field obtained in 2002 October. The
polarization of field stars confirms the previously determined interstellar
polarization along the line of sight to V838 Mon. While V838 Mon showed
intrinsic polarization shortly after its second outburst on 2002 February 8,
all subsequent observations only showed a quiescent interstellar polarization
component. We find V838 Mon once again showed significant intrinsic
polarization in 2002 October, suggesting the presence of an asymmetrical
geometry of scattering material close to the star. Furthermore, an observed 90
degree position angle flip in the intrinsic polarization from 2002 February to
2002 October suggests that the distribution of nearby circumstellar material
has experienced significant changes. We discuss the opacity changes in the
evolving circumstellar cloud around V838 Mon that may explain these
observations.


title: Optical, Ultraviolet, and Infrared Observations of SN 1993J

abstract:
  We review the existing set of optical/UV/IR observations of Supernova 1993J,
concentrating heavily on optical data because these are by far the most
plentiful. Some results from theoretical modeling of the observations are also
discussed. SN 1993J has provided the best observational evidence for the
transformation of a SN from one spectral type to another, thereby providing a
link between Type II and Type Ib supernovae (SNe). This has strengthened the
argument that SNe Ib (and, by extension, SNe Ic) are core-collapse events. SN
1993J has remained relatively bright for 10 years; its late-time emission comes
from the collision of supernova ejecta with circumstellar gas that was released
by the progenitor prior to the explosion. The circumstellar material shows
strong evidence of CNO processing.


title: Computing Non- Gaussian Maps of the CMB

abstract:
  We discuss methods to compute maps of the CMB in models featuring active
causal sources and in non-Gaussian models ofinflation. We show our large angle
results as well as some preliminary results on small angles. We conclude by
discussing on-going work.


title:
Force-Free Magnetosphere of an Accretion Disk -- Black Hole System. I.
  Schwarzschild Geometry

abstract:
  In this paper I study the magnetosphere of a black hole that is connected by
the magnetic field to a thin conducting Keplerian disk. I consider the case of
a Schwarzschild black hole only, leaving the more interesting but difficult
case of a Kerr black hole to a future study. I assume that the magnetosphere is
ideal, stationary, axisymmetric, and force-free. I pay a special attention to
the two singular surfaces present in the system, i.e., the event horizon and
the inner light cylinder; I use the regularity condition at the light cylinder
to determine the poloidal electric current as a function of poloidal magnetic
flux. I solve numerically the Grad--Shafranov equation, which governs the
structure of the magnetosphere, for two cases: the case of a nonrotating disk
and the case of a Keplerian disk. I find that, in both cases, the poloidal flux
function on the horizon matches a simple analytical expression corresponding to
a radial magnetic field that is uniform on the horizon. Using this result, I
express the poloidal current as an explicit function of the flux and find a
perfect agreement between this analytical expression and my numerical results.


title:
The Evolution of Early-type Field Galaxies Selected from a NICMOS Map of
  the Hubble Deep Field North

abstract:
  The redshift distribution of well-defined samples of distant early-type
galaxies offers a means to test the predictions of monolithic and hierarchical
galaxy formation scenarios. NICMOS maps of the entire Hubble Deep Field North
in the F110W and F160W filters, when combined with the available WFPC2 data,
allow us to calculate photometric redshifts and determine the morphological
appearance of galaxies at rest-frame optical wavelengths out to z ~ 2.5. Here
we report results for two subsamples of early-type galaxies, defined primarily
by their morphologies in the F160W band, which were selected from the NICMOS
data down to H160_{AB} < 24.0. The observed redshift distributions of our two
early-type samples do not match that predicted by a monolithic collapse model,
which shows an overabundance at z > 1.5. A hierarchical formation model better
matches the redshift distribution of the HDF-N early-types at z > 1.5, but
still does not adequately describe the observed early-types. The hierarchical
model predicts significantly bluer colors on average than the observed
early-type colors, and underpredicts the observed number of early-types at z <
1. [abridged]


title: Experimental Limit on the Cosmic Diffuse Ultra-high Energy Neutrino Flux

abstract:
  We report results from 120 hours of livetime with the Goldstone Lunar
Ultra-high energy neutrino Experiment (GLUE). The experiment searches for <10
ns microwave pulses from the lunar regolith, appearing in coincidence at two
large radio telescopes separated by 22 km and linked by optical fiber. Such
pulses would arise from subsurface electromagnetic cascades induced by
interactions of >= 100 EeV neutrinos in the lunar regolith. No candidates are
yet seen, and the implied limits constrain several current models for
ultra-high energy neutrino fluxes.


title: Constraining the Topology of the Universe

abstract:
  The first year data from the Wilkinson Microwave Anisotropy Probe are used to
place stringent constraints on the topology of the Universe. We search for
pairs of circles on the sky with similar temperature patterns along each
circle. We restrict the search to back-to-back circle pairs, and to nearly
back-to-back circle pairs, as this covers the majority of the topologies that
one might hope to detect in a nearly flat universe. We do not find any matched
circles with radius greater than 25 degrees. For a wide class of models, the
non-detection rules out the possibility that we live in a universe with
topology scale smaller than 24 Gpc.


title: Determination of the calorimetric energy in extensive air showers

abstract:
  The contribution of different components of an air shower to the total energy
deposit in the atmosphere, for different angles and primary particles, was
studied using the CORSIKA air shower simulation code. The amount of missing
energy, parameterized in terms of the calorimetric energy, was calculated. The
results show that this parameterization varies less than 1% with angle or
observation level. The dependence with the primary mass is less than 5% and,
with the high energy hadronic interaction model, less than 2%. The systematic
error introduced by the use of just one parameterization of the missing energy
correction function, for an equal mixture of proton and iron at 45deg, was
calculated to be below 3%. We estimate the statistical error due to
shower-to-shower fluctuations to be about 1%.


title:
Phase analysis of the 1-year WMAP data and its application for the CMB
  foreground separation

abstract:
  We present a new method based on phase analysis for the Galaxy and foreground
component separation from the cosmic microwave background (CMB) signal. This
method is based on a prevailing assumption that the phases of the underlying
CMB signal should have no or little correlation with those of the foregrounds.
This method takes into consideration all the phases of each multipole mode (l
<= 50, -l <= m <=l) from the whole sky without galactic cut, masks or any
dissection of the whole sky into disjoint regions. We use cross correlation of
the phases to illustrate that significant correlations of the foregrounds
manifest themselves in the phases of the WMAP 5 frequency bands, which are used
for separation of the CMB from the signals. Our final phase-cleaned CMB map has
the angular power spectrum in agreement with both the WMAP result and that from
Tegmark, de Oliveira-Costa and Hamilton (TOH), the phases of our derived CMB
signal, however, are slightly different from those of the WMAP Internal Linear
Combination map and the TOH map.