title:
Ionizing radiation fluctuations and large-scale structure in the
  Lyman-alpha forest

abstract:
  We investigate the large-scale inhomogeneities of the hydrogen ionizing
radiation field in the Universe at redshift z=3. Using a raytracing algorithm,
we simulate a model in which quasars are the dominant sources of radiation. We
make use of large scale N-body simulations of a LambdaCDM universe, and include
such effects as finite quasar lifetimes and output on the lightcone, which
affects the shape of quasar light echoes. We create Lya forest spectra that
would be generated in the presence of such a fluctuating radiation field,
finding that the power spectrum of the Lya forest can be suppressed by as much
as 15 % for modes with k=0.05-1 Mpc/h. This relatively small effect may have
consequences for high precision measurements of the Lya power spectrum on
larger scales than have yet been published. We also investigate another
radiation field probe, the cross-correlation of quasar positions and the Lya
forest. For both quasar lifetimes which we simulate (10^7 yr and 10^8 yr), we
expect to see a strong decrease in the Lya absorption close to other quasars
(the ``foreground'' proximity effect). We then use data from the Sloan Digital
Sky Survey First Data Release to make an observational determination of this
statistic. We find no sign of our predicted lack of absorption, but instead
increased absorption close to quasars. If the bursts of radiation from quasars
last on average < 10^6 yr, then we would not expect to be able to see the
foreground effect. However, the strength of the absorption itself seems to be
indicative of rare objects, and hence much longer total times of emission per
quasar. Variability of quasars in bursts with timescales > 10^4yr and < 10^6 yr
could reconcile these two facts.


title:
Efficiency Gains from Time Refinement on AMR Meshes and Explicit
  Timestepping

abstract:
  Block-structured AMR meshes are often used in astrophysical fluid
simulations, where the geometry of the domain is simple. We consider potential
efficiency gains for time sub-cycling, or time refinement (TR), on
Berger-Collela and oct-tree AMR meshes for explicit or local physics (such as
explict hydrodynamics), where the work per block is roughly constant with level
of refinement. We note that there are generally many more fine zones than there
are coarse zones. We then quantify the natural result that any overall
efficiency gains from reducing the amount of work on the relatively few coarse
zones must necessarily be fairly small. Potential efficiency benefits from TR
on these meshes are seen to be quite limited except in the case of refining a
small number of points on a large mesh -- in this case, the benefit can be made
arbitrarily large, albeit at the expense of spatial refinement efficiency.


title:
Cosmological variation of deuteron binding energy, strong interaction
  and quark masses from big bang nucleosynthesis

abstract:
  We use Big Bang Nucleosynthesis calculations and light element abundance data
to constrain the relative variation of the deuteron binding energy since the
universe was a few minutes old, $\delta Q = Q(BBN)-Q(present)$. Two approaches
are used, first treating the baryon to photon ratio, $\eta$, as a free
parameter, but with the additional freedom of varying $\delta Q$, and second
using the WMAP value of $\eta$ and solving only for $\delta Q$. Including
varying $Q$ yields a better fit to the observational data than imposing the
present day value, rectifying the discrepancy between the $^4He$ abundance and
the deuterium and $^7Li$ abundances, {\it and} yields good agreement with the
independently determined $\eta_{WMAP}$. The minimal deviation consistent with
the data is significant at about the 4-$\sigma$ level; $\delta Q/Q= -0.019 \pm
0.005$. If the primordial $^4$He abundance lies towards the low end of values
in the literature, this deviation is even larger and more statistically
significant. Taking the light element abundance data at face-value, our result
may be interpreted as variation of the dimensionless ratio
$X=m_s/\Lambda_{QCD}$ of the strange quark mass and strong scale: $\delta
X/X=(1.1 \pm 0.3) \times 10^{-3}$. These results provide a strong motivation
for a more thorough exploration of the potential systematic errors in the light
element abundance data.


title: Strong GeV Emission Accompanying TeV Blazar H1426+428

abstract:
  For High frequency BL Lac objects (HBLs) like H1426+428, a significant
fraction of their TeV gamma-rays emitted are likely to be absorbed in
interactions with the diffuse IR background, yielding $e^\pm$ pairs. The
resulting $e^\pm$ pairs generate one hitherto undiscovered GeV emission by
inverse Compton scattering with the cosmic microwave background photons
(CMBPs). We study such emission by taking the 1998-2000 CAT data, the
reanalyzed 1999 & 2000 HEGRA data and the corresponding intrinsic spectra
proposed by Aharonian et al. (2003a). We numerically calculate the scattered
photon spectra for different intergalactic magnetic field (IGMF) strengths. If
the IGMF is about $10^{-18}{\rm G}$ or weaker, there comes very strong GeV
emission, whose flux is far above the detection sensitivity of the upcoming
satellite GLAST! Considered its relatively high redshift ($z=0.129$), the
detected GeV emission in turn provides us a valuable chance to calibrate the
poor known spectral energy distribution of the intergalactic infrared
background, or provides us some reliable constraints on the poorly known IGMF
strength.


title: Non-adiabatic theoretical observables in Delta Scuti stars

abstract:
  Phase differences and amplitude ratios at different colour photometric bands
are currently being used to discriminate pulsation modes in order to facilitate
mode identification of kappa-driven non-radial pulsating stars. In addition to
physical inputs (e.g., mass, T_eff, etc.), these quantities depend on the
non-adiabatic treatment of the atmosphere. This paper presents theoretical
results concerning Delta Scuti pulsating stars. The envelope of each of these
stellar structures possesses a convection zone whose development is determined
by various factors. An interacting pulsation-atmosphere physical treatment is
introduced which supplies two basic non-adiabatic physical quantities: the
relative effective temperature variation and the phase lag phi^T, defined as
the angle between effective temperature variations and radial displacement.
These quantities can be used to derive the phase differences and amplitude
ratios. Numerical values for these quantities depend critically on the alpha
MLT parameter used to calculate the convection in the envelope. The dependence
on alpha was analized and it was found that the use of colour observations may
be of considerable importance in testing the MLT. Finally, examples are given
of how alpha introduces uncertainties in the theoretical predictions regarding
phases and amplitudes of photometric variations in Delta Scuti pulsating stars.


title: Precision Analysis of the Local Group Acceleration

abstract:
  We reexamine likelihood analyses of the Local Group (LG) acceleration, paying
particular attention to nonlinear effects. Under the approximation that the
joint distribution of the LG acceleration and velocity is Gaussian, two
quantities describing nonlinear effects enter these analyses. The first one is
the coherence function, i.e. the cross-correlation coefficient of the Fourier
modes of gravity and velocity fields. The second one is the ratio of velocity
power spectrum to gravity power spectrum. To date, in all analyses of the LG
acceleration the second quantity was not accounted for. Extending our previous
work, we study both the coherence function and the ratio of the power spectra.
With the aid of numerical simulations we obtain expressions for the two as
functions of wavevector and sigma_8. Adopting WMAP's best determination of
sigma_8, we estimate the most likely value of the parameter beta and its
errors. As the observed values of the LG velocity and gravity, we adopt
respectively a CMB-based estimate of the LG velocity, and Schmoldt et al.'s
(1999) estimate of the LG acceleration from the PSCz catalog. We obtain beta =
0.66^{+0.21}_{-0.07}; thus our errorbars are significantly smaller than those
of Schmoldt et al. This is not surprising, because the coherence function they
used greatly overestimates actual decoherence between nonlinear gravity and
velocity.


title:
Rotational effects on the oscillation frequencies of newly born
  proto-neutron stars

abstract:
  In this paper we study the effects of rotation on the frequencies of the
quasi-normal modes of a proto-neutron star (PNS) born in a gravitational
collapse during the first minute of life. Our analysis starts a few tenths of
seconds after the PNS formation, when the stellar evolution can be described by
a sequence of equilibrium configurations. We use the evolutionary models
developed by Pons et al. (1999; 2001) that describe how a non rotating star
cools down and contracts while neutrino diffusion and thermalization processes
dominate the stellar dynamics. For assigned values of the evolution time, we
set the star into slow rotation and integrate the equations of stellar
perturbations in the Cowling approximation, both in the time domain and in the
frequency domain, to find the quasi-normal mode frequencies. We study the
secular instability of the g-modes, that are present in the oscillation
spectrum due to the intense entropy and composition gradients that develop in
the stellar interior, and we provide an estimate of the growth time of the
unstable modes based on a post-Newtonian formula.


title: Can quantum theory explain dark matter?

abstract:
  Certain solutions to a gravitational form of Schrodinger's equation can yield
stable, macroscopic eigenstate solutions having no classical analogue, with
properties resembling those of dark matter. Some more tractable solutions show:
(1) radiative lifetimes far exceeding the universe's age, implying negligible
emission and inherent stability w.r.t. gravitational collapse, (2) negligible
interaction with EMR and visible matter, (3) potential to give rise to flat
rotation curves and (4) eigenstate energies and `sizes' consistent with that
expected for the galactic halo. Traditional baryonic particles occupying such
eigenstates will be invisible and weakly interacting, and may be assimilated
into galactic evolution scenarios without significantly disturbing BBN ratios.
It is proposed that such structures may explain the nature and origin of dark
matter.


title: The impact of cluster mergers on arc statistics

abstract:
  We study the impact of merger events on the strong lensing properties of
galaxy clusters. Previous lensing simulations were not able to resolve
dynamical time scales of cluster lenses, which arise on time scales which are
of order a Gyr. In this case study, we first describe qualitatively with an
analytic model how some of the lensing properties of clusters are expected to
change during merging events. We then analyse a numerically simulated lens
model for the variation in its efficiency for producing both tangential and
radial arcs while a massive substructure falls onto the main cluster body. We
find that: (1) during the merger, the shape of the critical lines and caustics
changes substantially; (2) the lensing cross sections for long and thin arcs
can grow by one order of magnitude and reach their maxima when the extent of
the critical curves is largest; (3) the cross section for radial arcs also
grows, but the cluster can efficiently produce this kind of arcs only while the
merging substructure crosses the main cluster centre; (4) while the arc cross
sections pass through their maxima as the merger proceeds, the cluster's X-ray
emission increases by a factor of $\sim5$. Thus, we conclude that accounting
for these dynamical processes is very important for arc statistics studies. In
particular, they may provide a possible explanation for the arc statistics
problem.


title:
Floquet analysis of disk instabilities and superhumps in Cataclysmic
  Variables

abstract: The paper has been deeply reviewed and compeltely re-written.


title: Early-type Galaxy Halo Dynamics inferred using the PN Spectrograph

abstract:
  A new instrument is providing crucial data with which to probe the structure
of dark halos in elliptical galaxies.


title: HST/STIS High Resolution Echelle Spectra of alpha Centauri A (G2 V)

abstract:
  We describe and analyze HST/STIS observations of the G2 V star alpha Centauri
A (alpha Cen A, HD 128620), a star similar to the Sun. The high resolution
echelle spectra obtained with the E140H and E230H gratings cover the complete
spectral range 1133-3150 Angstrom with a resolution of 2.6 km/s, an absolute
flux calibration accurate to +/-5%, and an absolute wavelength accuracy of
0.6-1.3 km/s. We present here a study of the E140H spectrum covering the
1140-1670 Angstrom spectral range, which includes 671 emission lines
representing 37 different ions and the molecules CO and H_2. For alpha Cen A
and the quiet and active Sun, we intercompare the redshifts, nonthermal line
widths, and parameters of two Gaussian representations of transition region
lines (e.g., Si IV, C IV), infer the electron density from the O IV intersystem
lines, and compare their differential emission measure distributions. One
purpose of this study is to compare the alpha Cen A and solar UV spectra to
determine how the atmosphere and heating processes in alpha Cen A differ from
the Sun as a result of the small differences in gravity, age, and chemical
composition of the two stars. A second purpose is to provide an excellent high
resolution UV spectrum of a solar-like star that can serve as a proxy for the
Sun observed as a point source when comparing other stars to the Sun.


title:
Mapping deflections of extragalactic Ultra-High Energy Cosmic Rays in
  magnetohydrodynamic simulations of the Local Universe

abstract:
  We construct a map of deflections of ultra-high energy cosmic rays by
extragalactic magnetic fields using a magneto-hydrodynamical simulation of
cosmic structure formation that realistically reproduces the positions of known
galaxy clusters in the Local Universe. Large deflection angles occur in cluster
regions, which however cover only an insignificant fraction of the sky. More
typical deflections of order $\lsim 1^\circ$ are caused by crossings of
filaments. For protons with energies $E \geq 4 \times 10^{19} {\rm eV}$,
deflections do not exceed a few degrees over most of the sky up to a
propagation distance of 500 Mpc. Given that the field strength of our simulated
intergalactic magnetic field forms a plausible upper limit, we conclude that
charged particle astronomy is in principle possible.


title: Stellar Kinematics of the Bulge from HST Proper Motion Measurements

abstract:
  I report on an ongoing programme of proper motion measurements in the
Galactic Bulge, using HST images. As a first application, the data are used to
derive the vertical gravitational acceleration on the minor axis of the Galaxy.
Implications of the measurement for the flattening of the Galactic potential
are discussed.


title: Generalized phantom energy

abstract:
  We examine cosmological models with generalized phantom energy (GPE).
Generalized phantom energy satisfies the supernegative equation of state, but
its evolution with the scale factor is generally independent, i.e. not
determined by its equation of state. The requirement of general covariance
makes the gravitational constant time-dependent. It is found that a large class
of distinct GPE models with different evolution of generalized phantom energy
density and gravitational constant, but the same equation of state of GPE have
the same evolution of the scale factor of the universe in the distant future.
The time dependence of the equation of state parameter determines whether the
universe will end in a de Sitter-like phase or diverge in finite time with the
accompanying "Big Rip" effect on the bound structures.


title: The Spectral Energy Distributions of Quasars and AGN

abstract:
  Active Galactic Nuclei (AGN) are multiwavelength emitters. To have any hope
of understanding them, or even to determine their energy output, we must
observe them with many telescopes. I will review what we have learned from
broad-band observations of relatively bright, low-redshift AGN over the past 15
years. AGN can be found at all wavelengths but each provides a different view
of the intrinsic population, often with little overlap between samples selected
in different wavebands. I look forward to the full view of the intrinsic
population which we will obtain over the next few years with surveys using
today's new, sensitive observatories. These surveys are already finding enough
new and different AGN candidates to pose the question "What IS an AGN?".


title: The stellar velocity distribution in the solar neighbourhood

abstract:
  We explore the heating of the velocity distribution in the solar
neighbourhood by stochastic spiral waves. Our investigation is based on direct
numerical integration of initially circular test-particle orbits in the sheared
sheet. We confirm the conclusion of other investigators that heating by spiral
structure can explain the principal features of the age-velocity dispersion
relation and other parameters of the velocity distribution in the solar
neighbourhood. In addition, we find that heating by strong transient spirals
can naturally explain the presence of small-scale structure in the velocity
distribution (``moving groups''). Heating by spiral structure also explains why
the stars in a single velocity-space moving group have a wide range of ages, a
result which is difficult to understand in the traditional model that these
structures result from inhomogeneous star formation. Thus we suggest that old
moving groups arise from irregularities in the Galactic potential rather than
irregularities in the star-formation rate.


title: X-ray emitting AGN unveiled by the Chandra Multiwavelength Project

abstract:
  We present an X-ray and optical analysis of a 2-8 keV flux limited (fx >
10e-14 erg s^-1 cm^-2) sample of 126 AGN detected in 16 Chandra fields. This
work represents a small though significant subset of the Chandra
Multiwavelength Project (ChaMP). We have chosen this limiting flux to have a
reasonable degree of completeness (50%) in our optical spectroscopic
identifications. The optical counterparts of these AGN are characterized as
either broad emission line AGN (BLAGN; 67%), narrow emission line galaxies
(NELG; 22%) or absorption line galaxies (ALG; 11%) without any evidence of an
AGN signature. Based on their X-ray luminosity and spectral properties, we show
that NELG and ALG are primarily the hosts of obscured AGN with an intrinsic
absorbing column in the range of 10^21.5<NH<10^23.3 cm^-2. While most of the
BLAGN are unobscured, there are a few with substantial absorption. X-ray
surveys such as the ChaMP nicely complement the SDSS to determine the
demographics of the AGN population.


title: Mapping the dark matter using weak lensing

abstract:
  Weak gravitational lensing of distant galaxies by foreground structures has
proven to be a powerful tool to study the mass distribution in the universe.
The advent of panoramic cameras on 4m class telescope has led to a first
generation of surveys that already compete with large redshift surveys in terms
of the accuracy with which cosmological parameters can be determined. The next
surveys, which already have started taking data, will provide another major
step forward. At the current level, systematics appear under control, and it is
expected that weak lensing will develop into a key tool in the era of precision
cosmology, provided we improve our knowledge of the non-linear matter power
spectrum and the source redshift distribution. In this review we will briefly
describe the principles of weak lensing and discuss the results of recent
cosmic shear surveys. We show how the combination of weak lensing and cosmic
microwave background measurements can provide tight constraints on cosmological
parameters. We also demonstrate the usefulness of weak lensing in studies of
the relation between the galaxy distribution and the underlying dark matter
distribution (``galaxy biasing''), which can provide important constraints on
models of galaxy formation. Finally, we discuss new and upcoming large cosmic
shear surveys.


title: Predicting Dust Distribution in Protoplanetary Discs

abstract:
  We present the results of three-dimensional numerical simulations that
include the effects of hydrodynamical forces and gas drag upon an evolving
dusty gas disk. We briefly describe a new parallel, two phase numerical code
based upon the smoothed particle hydrodynamics (SPH) technique in which the gas
and dust phases are represented by two distinct types of particles. We use the
code to follow the dynamical evolution of a population of grains in a gaseous
protoplanetary disk in order to understand the distribution of grains of
different sizes within the disk. Our ``grains'' range from metre to
submillimetre in size.


title:
Characterizing IMARAD CZT Detectors with Time Resolved Anode and Cathode
  Signals

abstract:
  We present the results of using standard IMARAD CZT detectors with a 100 MHz
readout of the anode and cathode pulses. The detectors, 2 cm x 2 cm large and
0.5 cm thick, have 64 Indium pixellated anode contacts at a pitch of 2.5 mm. We
investigate the possibilities to improve on the detector's photo-peak
efficiency and energy resolution using two depth of interaction (DOI)
indicators: (i) the total charge induced on the cathode and (ii) the drift time
of the electron cloud determined from the anode and/or the cathode pulses. The
DOI correction with the cathode charge gives better results, increasing the 662
keV photo-peak efficiency by 57% and improving the energy resolution from 2.33%
to 2.15% (FWHM, including the electronic noise). The information on the time
dependence of the induced charge can be used as a diagnostic tool to understand
the performance of the detector. Detailed comparison of the pulse shapes with
detector simulations gives the electron mobility and drift time and makes it
possible to assess the weighting potential and electric field inside the
detector


title: Connections Between Big and Small

abstract:
  Big-Bang cosmology and ideas for possible physics beyond the Standard Model
of particle physics are introduced. The density budget of the Universe is
audited, and the issues involved in calculating the baryon density from
microphysics are mentioned, as is the role of cold dark matter in the formation
of cosmological structures. Candidates for cold dark matter are introduced,
with particular attention to the lightest supersymmetric particle and
metastable superheavy relics. Prospects for detecting supersymmetric dark
matter in non-accelerator experiments are assessed, and the possible role of
decays in generating ultra-high-energy cosmic rays is discussed. More details
of these and other astroparticle topics are presented during the rest of this
Summer Institute.


title: Prospects for galaxy-mass relations from the 6dF Galaxy Survey

abstract:
  We develop new methods to study the properties of galaxy redshift surveys and
radial peculiar velocity surveys, both individually and combined. We derive the
Fisher information matrix for redshift surveys, including redshift distortions
and stochastic bias. We find exact results for estimating the marginalised
accuracy of a two-parameter measurement of the amplitude of galaxy clustering,
A_g, and the distortion parameter beta. The Fisher matrix is also derived for a
radial peculiar velocity survey and we discuss optimisation of these surveys
for equal timescales. The Fisher Super-Matrix, combining both surveys, is
derived. We apply these results to investigate the 6 degree Field Galaxy Survey
(6dFGS), currently underway on the UK Schmidt Telescope (UKST). The survey will
consist of approximately 125000 K-band selected galaxies with redshifts and a
subset of around 15000 galaxies with radial peculiar velocities. We find for
the redshift survey that we can measure the three parameters A_g, Gamma and
beta to about 3% accuracy, but will not be able to detect the baryon abundance,
or the matter-galaxy correlation coefficient, r_g. The peculiar velocity survey
will jointly measure the velocity amplitude A_v and Gamma to around 25%
accuracy. A conditional estimate of the amplitude A_v alone, can be made to 5%.
When the surveys are combined however, the major degeneracy between beta and
r_g is lifted and we are able to measure A_g, Gamma, beta and r_g all to the 2%
level, significantly improving on current estimates. Finally we consider scale
dependence of r_g and the biassing parameter b. We find that measurements for
these averaged over logarithmic passbands can be constrained to the level of a
few percent.


title: Cosmic Connections

abstract:
  A National Research Council study on connecting quarks with the cosmos has
recently posed a number of the more important open questions at the interface
between particle physics and cosmology. These questions include the nature of
dark matter and dark energy, how the Universe began, modifications to gravity,
the effects of neutrinos on the Universe, how cosmic accelerators work, and
whether there are new states of matter at high density and pressure. These
questions are discussed in the context of the talks presented at this Summer
Institute.


title: Void Hierarchy and Cosmic Structure

abstract:
  Within the context of hierarchical scenarios of gravitational structure
formation we describe how an evolving hierarchy of voids evolves on the basis
of {\em two} processes, the {\em void-in-void} process and the {\it
void-in-cloud} process. The related analytical formulation in terms of a {\it
two-barrier} excursion problem leads to a self-similarly evolving peaked void
size distribution.


title: uvbyHbeta CCD Photometry of Clusters. IV. Solving the Riddle of NGC 3680

abstract:
  CCD photometry on the uvbyCaHbeta system is presented for the open cluster,
NGC 3680. Restricting the data to probable cluster members using the CMD and
the photometric indices alone defines a sample of 34 stars at the cluster
turnoff that imply E(b-y)=0.042(0.002) or E(B-V) = 0.058(0.003), where the
errors (s.e.m) refer to internal errors alone. With this reddening, [Fe/H] is
derived from both m1 and hk using both b-y and Hbeta as the temperature
indices. The agreement among the four approaches is excellent, leading to final
value of [Fe/H] = -0.14 (0.03) for the cluster and removing the apparent
discrepancy between the past uvby analyses and extensive results from the red
giants for which the cause has been traced to an apparent zero-point offset in
the original m1 indices. Using the homogenized and combined V, b-y data from a
variety of studies transformed to B-V, the cluster CMD is compared to NGC 752,
IC 4651, and the core-convective-overshoot isochrones of Girardi et al. (2002).
By interpolation to the proper metallicity, it is found that the E(B-V), (m-M),
and age for NGC 752, IC 4651, and NGC 3680 are (0.03, 8.30, 1.55 Gyr), (0.10,
10.20, 1.7 Gyr), and (0.06, 10.20, 1.85 Gyr), respectively. The revised age and
metallicity sequence and the color distribution of the giants provide evidence
for the suggestion that the giants defining the apparent clump in NGC 3680 are
predominantly first-ascent giants, as indicated by their Li abundance, while
the clump stars in NGC 752, 0.1 mag bluer in (B-V), are He-core-burning stars.
When combined with the color distribution in IC 4651, it is suggested that over
this modest age range where He-core flash becomes important, the distribution
of so-called clump stars switches from being dominated by He-core burning stars
to first-ascent giants in the bump phase.


title: New Quasars Detected via Variability in the QUEST1 Survey

abstract:
  By observing the high galactic latitude equatorial sky in drift scan mode
with the QUEST (QUasar Equatorial Survey Team) Phase 1 camera, multi-bandpass
photometry on a large strip of sky, resolved over a large range of time scales
(from hourly to biennially) has been collected. A robust method of ensemble
photometry revealed those objects within the scan region that fluctuate in
brightness at a statistically significant level. Subsequent spectroscopic
observations of a subset of those varying objects easily discriminated the
quasars from stars. For a 13-month time scale, 38% of the previously known
quasars within the scan region were seen to vary in brightness and subsequent
spectroscopic observation revealed that approximately 7% of all variable
objects in the scan region are quasars. Increasing the time baseline to 26
months increased the percentage of previously known quasars which vary to 61%
and confirmed via spectroscopy that 7% of the variable objects in the region
are quasars. This reinforces previously published trends and encourages
additional and ongoing synoptic searches for new quasars and their subsequent
analysis. During two spectroscopic observing campaigns, a total of 30 quasars
were confirmed, 11 of which are new discoveries and 19 of which were determined
to be previously known. Using the previously cataloged quasars as a benchmark,
we have found it possible to better optimize future variability surveys. This
paper reports on the subset of variable objects which were spectroscopically
confirmed as quasars.


title:
The Occurrence of the Hall--Instability in Crusts of Isolated Neutron
  Stars

abstract:
  In former papers we showed that during the decay of a neutron star's magnetic
field under the influence of the Hall--drift, an unstable rise of small--scale
field structures at the expense of the large--scale background field may
happen. This linear stability analysis was based on the assumption of a uniform
density throughout the neutron star crust, whereas in reality the density and
all transport coefficients vary by many orders of magnitude. Here, we extend
the investigation of the Hall--drift induced instability by considering
realistic profiles of density and chemical composition, as well as background
fields with more justified radial profiles. Two neutron star models are
considered differing primarily in the assumption on the core matter equation of
state. For their cooling history and radial profiles of density and composition
we use known results to infer the conductivity profiles. These were fed into
linear calculations of a dipolar field decay starting from various initial
configurations. At different stages of the decay, snapshots of the magnetic
fields at the equator were taken to yield background field profiles for the
stability analysis. The main result is that the Hall instability may really
occur in neutron star crusts. Characteristic growth times are in the order of
\lesssim 10^4 ... 10^6 yrs depending on cooling age and background field
strength. The influence of the equation of state and of the initial field
configuration is discussed.


title: Gravitational Waves from Hyper-Accretion onto Nascent Black Holes

abstract:
  We examine the possibility that hyper-accretion onto newly born, black holes
occurs in highly intermittent, non-asymmetric fashion favorable to
gravitational wave emission in a neutrino cooled disk. This picture of
near-hole accretion is motivated by magneto-rotationally induced,
ultra-relativistic disk dynamics in the region of the flow bounded from below
by the marginally bound geodesic radius. For high spin values, a largely
coherent magnetic field in this region has the dynamical implication of compact
mass segregation at the displacement nodes of the non-axisymmetric, MRI modes.
When neutrino stress competes favorably for the disk dynamical structure, the
matter clumps may be rather dense and sufficiently long-lived to excite the
Quasi-Normal Ringing (a.k.a. QNR) modes of the Kerr geometry upon their
in-fall. We find that such accretion flow may drive bar-like, quadrupole
(l,m=2,2) modes in nearly resonant fashion for spin parameters $a \geq .9$. The
ensuing build up in strain amplitude of the undamped oscillations warrants a
brisk rate of energy deposition into gravitational waves. A detectability
assessment for the LIGO interferometers through the match filtering technique
is given by integrating the energy flux over a one second epoch of resonant
hyper-accretion at $1 \msun \sec^{-1}$. Thus, a $15 \msun$ Kerr black hole
spinning at $a \simeq .98$ ($f_{\rm QNR} \simeq 1677$ Hz), and located at 27
Mpc (e.g., GRB980425), will deliver a characteristic strain amplitude, $h_{\rm
char} \simeq 2.2_{-21}$, large enough to be detectable by LIGO II. If resonant
hyper-accretion were sustainable for a longer period (or at higher rates)
possibly associated with a second broad hump in a GRB light-curve, these
objects could be detected by LIGO I at very low redshifts.


title: Galactic Point Sources of TeV Antineutrinos

abstract:
  High energy cosmic ray experiments have identified an excess from the region
of the Galactic Plane in a limited energy range around $10^{18}$ eV (EeV). This
is very suggestive of neutrons as candidate primaries, because the directional
signal requires relatively-stable neutral primaries, and time-dilated neutrons
can reach Earth from typical Galactic distances when the neutron energy exceeds
an EeV. We here point out that if the Galactic messengers are neutrons, then
those with energies below an EeV will decay in flight, providing a flux of
cosmic antineutrinos above a TeV which is {\it observable} at a kilometer-scale
neutrino observatory. The expected event rate per year above 1 TeV in a
detector such as IceCube, for example, is 20 antineutrino showers (all flavors)
and a $1^\circ$ directional signal of 4 $\bar \nu_\mu$ events. A measurement of
this flux can serve to identify the first extraterrestrial point source of TeV
antineutrinos.


title:
X-ray Preionisation Powered by Accretion on the First Black Holes. I: a
  Model for the WMAP Polarisation Measurement

abstract:
  We investigate the possibility that there is a first phase of partial
ionisation due to X-rays produced by black hole accretion in small-mass
galaxies at redshifts 7<z<20. This is followed by complete reionisation by
stellar sources at z~7. This scenario is motivated by the large optical depth
to Thompson scattering, tau_e=0.17, measured by WMAP. But it is also consistent
with the observed Gunn-Peterson trough in the spectra of quasars at z~5-6. We
use a semianalytic code to explore models with different black hole accretion
histories and cosmological parameters.We find that ``preionisation'' by X-rays
can increase the intergalactic medium (IGM) optical depth from tau_e~0.06 given
by stellar sources only, to 0.1<tau_e<0.2, if a fraction of baryons 5x10^-5 is
accreted onto seed black holes produced in the collapse of low metallicity,
high mass stars before z~15. To be effective, preionisation requires a
non-negligible star formation in the first small-mass galaxies in hich seed
black holes are formed.The model predicts that dwarf spheroidal galaxies may
host a mass in black holes that is 5-40% of their stellar mass. The redshifted
X-ray background produced by this early epoch of black hole accretion
constitutes about 5-10% of the X-ray background in the 2-50 keV bands and
roughtly half of the currently estimated black hole mass density was formed at
early times.Moreover, in most models, the photons from the redshifted
background are sufficient to fully reionise HeII at redshift z~3 without any
additional contribution from quasars at lower redshifts and the temperature of
the mean density intergalactic medium remains close to 10^4 K down to redshift
z~1.[abridged]


title: High-Energy Neutrino Astronomy: from AMANDA to Icecube

abstract:
  Kilometer-scale neutrino detectors such as IceCube are discovery instruments
covering nuclear and particle physics, cosmology and astronomy. Examples of
their multidisciplinary missions include the search for the particle nature of
dark matter and for additional small dimensions of space. In the end, their
conceptual design is very much anchored to the observational fact that Nature
accelerates protons and photons to energies in excess of 10^{20} and 10^{13}
eV, respectively. The cosmic ray connection sets the scale of cosmic neutrino
fluxes. In this context, we discuss the first results of the completed AMANDA
detector and the reach of its extension, IceCube.


title:
Inflationary potentials yielding constant scalar perturbation spectral
  indices

abstract:
  We explore the types of slow-roll inflationary potentials that result in
scalar perturbations with a constant spectral index, i.e., perturbations that
may be described by a single power-law spectrum over all observable scales. We
devote particular attention to the type of potentials that result in the
Harrison--Zel'dovich spectrum.


title: Mapping the Cosmic Web with Ly-alpha Emission

abstract:
  We use a high-resolution cosmological simulation to predict the distribution
of HI Ly-alpha emission from the low-redshift (z<0.5) intergalactic medium
(IGM). Our simulation can be used to reliably compute the emission from
optically thin regions of the IGM but not that of self-shielded gas. We
therefore consider several models that bracket the expected emission from
self-shielded regions. Most galaxies are surrounded by extended (>10^2 kpc)
``coronae'' of optically thin gas with Ly-alpha surface brightness close to the
expected background. Most of these regions contain smaller cores of dense, cool
gas. Unless self-shielded gas is able to cool to T<10^4.1 K, these cores are
much brighter than the background. The Ly-alpha coronae represent ``cooling
flows'' of IGM gas accreting onto galaxies. We also estimate the number of
Ly-alpha photons produced through the reprocessing of stellar ionizing
radiation in the interstellar medium of galaxies; while this mechanism is
responsible for the brightest Ly-alpha emission, it occurs on small physical
scales and can be separated using high-resolution observations. In all cases,
we find that Ly-alpha emitters are numerous (with a space density ~0.1 h^3
Mpc^-3) and closely trace the filamentary structure of the IGM, providing a new
way to map gas inside the cosmic web.


title: NIR Observations of the QSO 3C 48 Host Galaxy

abstract:
  In this paper we present new near infrared (NIR) imaging and spectroscopic
data of the quasar 3C 48 and its host galaxy. The data were obtained with the
ESO-VLT camera ISAAC.We report the first detection of the apparent second
nucleus 3C 48A about 100NE of the bright QSO nucleus in the NIR bands J, H, and
Ks. 3C 48A is highly reddened with respect to the host, which could be due to
warm dust, heated by enhanced star formation or by interstellar material
intercepting the radio jet. In fact, all colors on the host galaxy are reddened
by several magnitudes of visual extinction. Imaging and initial spectroscopy
also reveal a stellar content of about 30% to the overall QSO-light in the NIR.
These results are important input parameters for future models of the stellar
populations by taking extinction into account.


title:
High redshift quasars and the supermassive black hole mass budget:
  constraints on quasar formation models

abstract:
  We investigate the constraints on models of supermassive black hole (SMBH)
and quasar formation obtainable from two recent observational developments: the
discovery of luminous quasars at z~6, and estimates of the local mass density
of SMBHs. If ~90 per cent of this mass was accreted at redshifts z<3, as
suggested by the observed quasar luminosity functions, these joint constraints
pose a challenge for models, which must account for the observed luminous
quasar population at z~6 within a very limited `mass budget'. We investigate a
class of models based within the hierarchical structure formation scenario, in
which major mergers lead to black hole formation and fuelling, and the
resulting quasars shine at their Eddington-limited rate until their fuel is
exhausted. We show that the simplest such model, in which a constant fraction
of the gas within the halo is accreted in each major merger, cannot satisfy
both constraints simultaneously. When this model is normalized to reproduce the
number density of luminous quasars at z~6, the mass budget is grossly exceeded
due to an overabundance of lower mass SMBHs. We explore a range of
modifications to the simple model designed to overcome this problem. We show
that both constraints can be satisfied if the gas accretion fraction scales as
a function of the halo virial velocity. Similar scalings have been proposed in
order to reproduce the local M-sigma relation. Successful models can also be
constructed by restricting the formation of seed black holes to redshifts above
z~11.5 or to haloes above a velocity threshold ~55 km/s, or assuming that only
a fraction of major mergers result in formation of a seed SMBH. (abridged)


title: Could There Be A Hole In Type Ia Supernovae?

abstract:
  In the favored progenitor scenario, Type Ia supernovae arise from a white
dwarf accreting material from a non-degenerate companion star. Soon after the
white dwarf explodes, the ejected supernova material engulfs the companion
star; two-dimensional hydrodynamical simulations by Marietta et. al. show that,
in the interaction, the companion star carves out a conical hole of opening
angle 30-40 degrees in the supernova ejecta. In this paper we use
multi-dimensional Monte Carlo radiative transfer calculations to explore the
observable consequences of an ejecta-hole asymmetry. We calculate the variation
of the spectrum, luminosity, and polarization with viewing angle for the
aspherical supernova near maximum light. We find that the supernova looks
normal from almost all viewing angles except when one looks almost directly
down the hole. In the latter case, one sees into the deeper, hotter layers of
ejecta. The supernova is relatively brighter and has a peculiar spectrum
characterized by more highly ionized species, weaker absorption features, and
lower absorption velocities. The spectrum viewed down the hole is comparable to
the class of SN 1991T-like supernovae. We consider how the ejecta-hole
asymmetry may explain the current spectropolarimetric observations of SNe Ia,
and suggest a few observational signatures of the geometry. Finally, we discuss
the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry
may fit in as one of several possible sources of diversity.


title:
A dwarf galaxy remnant in Canis Major: the fossil of an in-plane
  accretion onto the Milky Way

abstract:
  We present an analysis of the asymmetries in the population of Galactic
M-giant stars present in the 2MASS All Sky catalogue. Several large-scale
asymmetries are detected, the most significant of which is a strong
elliptical-shaped stellar over-density, close to the Galactic plane at (l=240,
b=-8), in the constellation of Canis Major. A small grouping of globular
clusters (NGC 1851, NGC 1904, NGC 2298, and NGC 2808), coincident in position
and radial velocity, surround this structure, as do a number of open clusters.
The population of M-giant stars in this over-density is similar in number to
that in the core of the Sagittarius dwarf galaxy. We argue that this object is
the likely dwarf galaxy progenitor of the ring-like structure that has recently
been found at the edge of the Galactic disk. A numerical study of the tidal
disruption of an accreted dwarf galaxy is presented. The simulated debris fits
well the extant position, distance and velocity information on the ``Galactic
Ring'', as well as that of the M-giant over-densities, suggesting that all
these structures are the consequence of a single accretion event. The disrupted
dwarf galaxy stream orbits close to the Galactic Plane, with a pericentre at
approximately the Solar circle, an orbital eccentricity similar to that of
stars in the Galactic thick disk, as well as a vertical scale height similar to
that of the thick disk. This finding strongly suggests that the Canis Major
dwarf galaxy is a building block of the Galactic thick disk, that the thick
disk is continually growing, even up to the present time, and that thick disk
globular clusters were accreted onto the Milky Way from dwarf galaxies in
co-planar orbits.


title: On the turbulent $\alpha$-disks and the intermittent activity in AGN

abstract:
  We consider effects of the MHD turbulence on the viscosity during the
evolution of the thermal-viscous ionization instability in the standard
$\alpha$-accretion disks. We consider the possibility that the accretion onto a
supermassive black hole proceeds through an outer standard accretion disk and
inner, radiatively inefficient and advection dominated flow. In this scenario
we follow the time evolution of the accretion disk in which the viscosity
parameter $\alpha$ is constant throughout the whole instability cycle, as
implied by the strength of MHD turbulence. We conclude that the hydrogen
ionization instability is a promising mechanism to explain the intermittent
activity in AGN.


title:
Detection possibility of the pair-annihilation neutrinos from the
  neutrino-cooled pre-supernova star

abstract:
  The signal produced in neutrino observatories by the pair-annihilation
neutrinos emitted from a 20 $M_{\odot}$ pre-supernova star at the silicon
burning phase is estimated. The spectrum of the neutrinos with an average
energy $\sim$2 MeV is calculated with the use of the Monte Carlo method. A few
relevant reactions for neutrinos and anti-neutrinos in modern detectors are
considered. The most promising results are from $\bar{\nu}_e + p
\longrightarrow n + e^{+}$ reaction. During the Si-burning phase we expect 1.27
neutrons/day/kiloton of water to be produced by neutrinos from a star located
at a distance of 1 kpc. Small admixture of effective neutron-absorbers as e.g.
NaCl or GdCl$_{3}$ makes these neutrons easily visible because of Cherenkov
light produced by electrons which were hit by $\sim$8 MeV photon cascade
emitted by Cl or Gd nuclei. The estimated rate of neutron production for SNO
and Super-Kamiokande is, respectively, 2.2 and 41 events per day for a star at
1 kpc. For future detectors UNO and Hyper-Kamiokande we expect 5.6 and 6.9
events per day even for a star 10 kpc away. This would make it possible to
foresee a massive star death a few days before its core collapse. Importance of
such a detection for theoretical astrophysics is discussed.


title:
When Do Planets Form? A Search for Extra-solar Planets Around Metal-Poor
  Stars

abstract:
  We present preliminary results from our spectroscopic search for planets
within 1 AU of metal-poor field dwarfs using NASA time with HIRES on Keck I.
The core accretion model of gas giant planet formation is sensitive to the
metallicity of the raw material, while the disk instability model is not. By
observing metal-poor stars in the field we eliminate the role of dynamical
interactions in dense stellar environments, such as a globular cluster. The
results of our survey should allow us to distinguish the relative roles of the
two competing giant planet formation scenarios.


title:
Cooling by Heat Conduction Inside Magnetic Flux Loops and the Moderate
  Cluster Cooling Flow Model

abstract:
  I study non-radiative cooling of X-ray emitting gas via heat conduction along
magnetic field lines inside magnetic flux loops in cooling flow clusters of
galaxies. I find that such heat conduction can reduce the fraction of energy
radiated in the X-ray band by a factor of 1.5-2. This non-radiative cooling
joins two other proposed non-radiative cooling processes, which can be more
efficient. These are mixing of cold and hot gas, and heat conduction initiated
by magnetic fields reconnection between hot and cold gas. These processes when
incorporated into the moderate cooling flow model lead to a general cooling
flow model with the following ingredients. (1) Cooling flow does occur, but
with a mass cooling rate about 10 times lower than in old versions of the
cooling flow model. Namely, heating occurs such that the effective age of the
cooling flow is much below the cluster age, but the heating can't prevent
cooling altogether. (2) The cooling flow region is in a non-steady state
evolution. (3) Non-radiative cooling of X-ray emitting gas can bring the model
to a much better agreement with observations. (4) The general behavior of the
cooling flow gas, and in particular the role played by magnetic fields, make
the intracluster medium in cooling flow clusters similar in some aspects to the
active solar corona.


title: Loop quantum gravity effects on inflation and the CMB

abstract:
  In loop quantum cosmology, the universe avoids a big bang singularity and
undergoes an early and short super-inflation phase. During super-inflation,
non-perturbative quantum corrections to the dynamics drive an inflaton field up
its potential hill, thus setting the initial conditions for standard inflation.
We show that this effect can raise the inflaton high enough to achieve
sufficient e-foldings in the standard inflation era. We analyze the
cosmological perturbations generated when slow-roll is violated after
super-inflation, and show that loop quantum effects can in principle leave an
indirect signature on the largest scales in the CMB, with some loss of power
and running of the spectral index.


title: The scaling of the X-ray variability with black hole mass in AGN

abstract:
  The relation between the 2-10 keV, long term, excess variance and AGN black
hole mass is considered in this work. A significant anti-correlation is found
between these two quantities in the sense that the excess variance decreases
with increasing black hole mass. This anti-correlation is consistent with the
hypothesis that the 2-10 keV power spectrum in AGN follows a power law of slope
-2 at high frequencies. It then flattens to a slope of -1 below a break
frequency until a second break frequency below which it flattens to a slope of
zero. The ratio of the two break frequencies is equal to 10-30, similar to the
ratio of the respective frequencies in Cyg X-1. The power spectrum amplitude in
the "frequency x power" space does not depend on black hole mass. Instead it is
roughly equal to 0.02 in all objects. The high frequency break decreases with
increasing black hole mass according to the relation 1.5x(10^-6)/(BHmass/(10^7)
solar masses) Hz, in the case of "classical" Seyfert 1 galaxies. The excess
variance of NGC4051, a Narrow Line Seyfert 1 object, is larger than what is
expected for its black hole mass and X-ray luminosity. This can be explained if
its high frequency break is 20 times larger than the value expected in the case
of a "classical" Seyfert 1 with the same black hole mass. Finally, the excess
variance vs X-ray luminosity correlation is a byproduct of the excess variance
vs black hole mass correlation, with AGN accreting at ~ 0.1-0.15 the Eddington
limit. These results are consistent with recent results from the power spectral
analysis of AGN.


title: The Properties and the Evolution of the Highly Ionized Gas in MR2251-178

abstract:
  We present the first XMM-Newton observations of the radio-quiet quasar
MR2251-178. We model the X-ray spectrum with two power laws, one at high
energies with a slope of \Gamma=1.6 and the other to model the soft excess with
a slope of \Gamma=2.9, both absorbed by at least two warm absorbers (WAs). The
high-resolution grating spectrum shows emission lines from N VI, O VII, O VIII,
Ne IX, and Ne X, as well as absorption lines from the low ionization ions O
III, O IV, and O V. A study of the spectral variations in MR2251-178 over a
period of 8.5 years yields that all X-ray observations can be fitted with the
above model. Luminosity variations over timescales of years seem to correlate
with the soft excess variations but not with the WA properties variations. The
overall picture is that of a stratified WA that enters and disappears from the
line-of-sight on timescales of several months. We also present the first FUSE
spectrum of MR2251-178. The general characteristics of the UV and X-ray
absorbers seem to be consistent.


title:
Testing Circuit Models for the Energies of Coronal Magnetic Field
  Configurations

abstract:
  Circuit models involving bulk currents and inductances are often used to
estimate the energies of coronal magnetic field configurations, in particular
configurations associated with solar flares. The accuracy of circuit models is
tested by comparing calculated energies of linear force-free fields with
specified boundary conditions with corresponding circuit estimates. The circuit
models are found to provide reasonable (order of magnitude) estimates for the
energies of the non-potential components of the fields, and to reproduce
observed functional dependences of the energies. However, substantial departure
from the circuit estimates is observed for large values of the force-free
parameter, and this is attributed to the influence of the non-potential
component of the field on the path taken by the current.


title: The First Stars

abstract:
  We review recent theoretical results on the formation of the first stars in
the universe, and emphasize related open questions. In particular, we discuss
the initial conditions for Population III star formation, as given by variants
of the cold dark matter cosmology. Numerical simulations have investigated the
collapse and the fragmentation of metal-free gas, showing that the first stars
were predominantly very massive. The exact determination of the stellar masses,
and the precise form of the primordial initial mass function, is still hampered
by our limited understanding of the accretion physics and the protostellar
feedback effects. We address the importance of heavy elements in bringing about
the transition from an early star formation mode dominated by massive stars, to
the familiar mode dominated by low mass stars, at later times. We show how
complementary observations, both at high redshifts and in our local cosmic
neighborhood, can be utilized to probe the first epoch of star formation.


title: The rotation curves of dwarf galaxies: a problem for Cold Dark Matter?

abstract:
  We address the issue of accuracy in recovering density profiles from
observations of rotation curves of galaxies. We ``observe'' and analyze our
models in much the same way as observers do the real galaxies. We find that the
tilted ring model analysis produces an underestimate of the central rotational
velocity. In some cases the galaxy halo density profile seems to have a flat
core, while in reality it does not. We identify three effects, which explain
the systematic biases: (1) inclination (2), small bulge, and (3) bar. The
presence of even a small non-rotating bulge component reduces the rotation
velocity. In the case of a disk with a bar, the underestimate of the circular
velocity is larger due to a combination of non-circular motions and random
velocities. Signatures of bars can be difficult to detect in the surface
brightness profiles of the model galaxies. The variation of inclination angle
and isophote position angle with radius are more reliable indicators of bar
presence than the surface brightness profiles. The systematic biases in the
central ~ 1 kpc of galaxies are not large. Each effect separately gives
typically a few kms error, but the effects add up. In some cases the error in
circular velocity was a factor of two, but typically we get about 20 percent.
The result is the false inference that the density profile of the halo flattens
in the central parts. Our observations of real galaxies show that for a large
fraction of galaxies the velocity of gas rotation (as measured by emission
lines) is very close to the rotation of stellar component (as measured by
absorption lines). This implies that the systematic effects discussed in this
paper are also applicable both for the stars and emission-line gas.


title: HI absorption in a gravitational lens at $z \sim 0.7645$

abstract:
  We have used the Westerbork Synthesis Radio Telescope to detect HI 21cm
absorption at $z \sim 0.7645$ in the gravitational lens system towards PMN
J0134-0931. The 21cm profile has two broad components, with peak optical depths
of $0.047 \pm 0.007$ and $0.039 \pm 0.007$, at heliocentric redshifts $0.76470
\pm 0.00006$ and $0.76348 \pm 0.00006$, respectively. The redshift of the
stronger component matches that of CaII H and K absorption detected earlier.
The absorption has a total velocity width of $\sim 500$ km/s (between nulls)
and an equivalent width of $7.1 \pm 0.08$ km/s. This would imply a total HI
column density of $2.6 \pm 0.3 \times 10^{21}$ per cm$^2$, for a spin
temperature of 200 K and a covering factor of unity. The high estimated HI
column density is consistent with the presence of large amounts of dust at the
lens redshift; the intervening dust could be responsible for the extremely red
colour of the background quasar.


title: High-Energy Radiation Probes of Protostellar Envelopes

abstract:
  We present observations of molecular high-energy radiation probes and report
the first detections of CO+ toward W3 IRS5, a source containing ultracompact
HII regions. UV radiation and X-rays from the central objects may enhance
molecules due to photodissociation and ionization processes. To study the
effects on the immediate YSO environment, we are developing time- and
depth-dependant chemical models containing UV and X-ray chemistry, by extending
the models of Doty et al. (2002). Molecules like CO+ or NO may be used as
tracers of very early X-ray emission in regions of high extinction, from which
no X-ray photons can be detected.


title: The sigma_c-V_c correlation in high and low surface brightness galaxies

abstract:
  We investigate the relation between the central velocity dispersion, sigma_0,
and the circular velocity, V_c, in galaxies. In addition to previously
available data, we consider an observationally homogeneus sample of 52 high
surface brightness and 11 low surface brightness spiral galaxies. We performed
a straight line regression analysis in a linear scale, finding a good fit, also
for low sigma_0 galaxies, always rejected in the previous studies. Low surface
brightness galaxies seem to behave differently, showing either higher values of
V_c or lower values of sigma_0 with respect to their high surface brightness
counterparts.


title: Hot Dust in Radio-Loud Active Galactic Nuclei

abstract:
  We have measured mid-infrared (MIR) fluxes of 3C sources on images taken with
ISOCAM onboard the Infrared Space Observatory (ISO). The photometric data were
combined with existing photometry at other wavelengths to assemble the spectral
energy distribution (SED) for each galaxy from infrared to radio wavelengths.
In addition, we used ISOPHOT spectra to compute average MIR spectra for
different types of Active Galactic Nuclei (AGNs). The MIR emission of 53 of our
sources shows evidence of dust. We find a clear correlation between the SEDs,
emission from polycyclic aromatic hydrocarbons (PAHs), and the type of AGN.
Specifically, we find that in broad emission line radio galaxies (BLRGs), the
dust emission peaks at ~40 microns and PAH bands are weak, whereas emission in
comparable narrow line radio galaxies (NLRGs) peaks at a longer wavelength of
\~100microns and the PAH bands are much stronger. Although less pronounced, a
similar trend is seen when comparing quasars (QSOs) with high-luminosity NLRGs.
We used dust radiative transfer models with a central heating source to
describe the SEDs. The difference in the dust emission appears to be the effect
of heating by radiation from the central engine. In type~1 AGNs (BLRGs and
QSOs), the broad line region (BLR) is directly visible and therefore hot
(T>~300K) dust dominates the emission. In this region, PAHs are destroyed which
explains the weak PAH emission. On the other hand, the BLR is hidden in type~2
AGNs (NLRGs). Their SEDs are therefore dominated by cooler dust including PAHs.


title: A new strongly X-ray flaring M9 dwarf in the solar neighborhood

abstract:
  We report on the discovery of a very low mass (VLM) star in the solar
neighborhood, originally identified as an optical counterpart of a flaring
X-ray source detected in the ROSAT All-Sky survey. Optical spectroscopy and
infrared photometry consistently reveal a spectral type of M9 \pm 0.5 and a
distance of ~11 pm 2pc. The optical counterpart of 1RXS J115928.5-524717 shows
a large proper motion of 1.08\pm0.06 "/year. 1RXS~J115928.5-524717 is the
fourth object among the VLM stars displaying a huge X-ray flare, reaching the
unprecedent value of L_X/L_{bol}~0.1.


title:
VLT + UVES Spectroscopy of the Low-Ionization Intrinsic Absorber in SDSS
  J001130.56+005550.7

abstract:
  We analyse high-resolution VLT+UVES spectra of the low-ionization intrinsic
absorber observed in the BAL QSO SDSS J001130.56+005550.7. Two narrow
absorption systems at velocities -600 km/s and -22000 km/s are detected. The
low-velocity system is part of the broad absorption line (BAL), while the
high-velocity one is well detached. While most narrow absorption components are
only detected in the high-ionization species, the lowest velocity component is
detected in both high- and low-ionization species, including in the excited
SiII* and CII* lines. From the analysis of doublet lines, we find that the
narrow absorption lines at the low-velocity end of the BAL trough are
completely saturated but do not reach zero flux, their profiles being dominated
by a velocity-dependent covering factor. The covering factor is significantly
smaller for MgII than for SiIV and NV, which demonstrates the intrinsic nature
of absorber. From the analysis of the excited SiII* and CII* lines in the
lowest velocity component, we find an electron density ~ 1000 cm^{-3}. Assuming
photoionization equilibrium, we derive a distance ~ 20 kpc between the
low-ionization region and the quasar core. The correspondence in velocity of
the high- and low-ionization features suggests that all these species must be
closely associated, hence formed at the same distance of ~ 20 kpc, much higher
than the distance usually assumed for BAL absorbers.


title:
The Nearby QSO Host I Zw 1: NIR Probing of Structural Properties and
  Stellar Populations

abstract:
  The likely merger process and the properties of the stellar populations in
the I Zw 1 host galaxy are analyzed on the basis of multi-wavelength
observations (with the ISAAC camera at the Very Large Telescope (VLT/UT1) of
the European Southern Observatory (ESO), Chile (Paranal), with the
interferometer of the Berkeley-Illinois-Maryland Association (BIMA), USA (Hat
Creek/California), and with the IRAM Plateau de Bure Interferometer (PdBI),
France) and N-body simulations. The data give a consistent picture of I Zw 1,
with properties between those of ultra-luminous infrared galaxies (ULIRGs) and
QSOs as displayed by transition objects in the evolutionary sequence of active
galaxies.


title: On Solar Radius Variation with Magnetic Field

abstract:
  In response to the claim by Dziembowski et al. (2001) that the solar radius
decreases with magnetic activity at the rate of 1.5 km/yr, we consider the
theoretical question whether a radius variation is expected with the solar
cycle. If the radius variation is caused by the magnetic pressure of toroidal
flux tubes at the bottom of the convection zone, then the dynamo model of Nandy
and Choudhuri (2002) would suggest a radius decrease with magnetic activity, in
contrast to other dynamo models which would suggest a radius increase. However,
the radius decrease is estimated to be only of the order of hundreds of metres.


title:
X-ray and optical counterparts of hard X-ray selected sources from the
  SHEEP survey: first results

abstract:
  We present followup observations of five hard X-ray sources from the ASCA
5-10 keV SHEEP survey, which has a limiting flux of $\sim 10^{-13}$ erg
cm$^{-2}$ s$^{-1}$. Chandra data have been obtained to improve the X-ray
positions from a few arcmin to $<1''$, which allows unambiguous optical
identification. While the objects almost certainly house AGN based on their
X-ray luminosity, optical spectroscopy reveals a variety of properties. The
identifications indicate that the SHEEP survey samples the same populations as
deeper surveys which probe the origin of the X-ray background, but because the
SHEEP sources are far brighter, they are more amenable to detailed followup
work. We find a variety of classifications and properties, including a type II
QSO, a galaxy undergoing star formation, and a broad-line AGN which has a very
hard X-ray spectrum, indicating substantial absorption in the X-ray but none in
the optical. Two objects have X-ray/optical flux ratios which, were they at an
X-ray flux level typical of objects in Chandra deep surveys, would place them
in the ``optically faint'' category. They are both identified with broad line
QSOs at z$\sim 1$. Clearly this survey - which is relatively unbiased against
obscured objects - is revealing a set of remarkable objects quite different to
the familiar classes of AGN found in previous optical and soft X-ray surveys.


title:
The H alpha Galaxy Survey I. The galaxy sample, H alpha narrow-band
  observations and star formation parameters for 334 galaxies

abstract:
  We discuss the selection and observations of a large sample of nearby
galaxies, which we are using to quantify the star formation activity in the
local Universe. The sample consists of 334 galaxies across all Hubble types
from S0/a to Im and with recession velocities of between 0 and 3000 km/s. The
basic data for each galaxy are narrow band H alpha plus [NII] and R-band
imaging, from which we derive star formation rates, H alpha plus [NII]
equivalent widths and surface brightnesses, and R-band total magnitudes. A
strong correlation is found between total star formation rate and Hubble type,
with the strongest star formation in isolated galaxies occurring in Sc and Sbc
types. More surprisingly, no significant trend is found between H alpha plus
[NII] equivalent width and galaxy R-band luminosity. More detailed analyses of
the data set presented here will be described in subsequent papers.


title:
Why do millisecond pulsars have weaker magnetic fields compared to
  ordinary pulsars?

abstract:
  Millisecond pulsars, with magnetic fields weaker by three to four orders
compared to those of ordinary pulsars, are presumed to be neutron stars spun up
by binary accretion. We expect the magnetic field to get screened by the
accreted material. Our simulation of this screening mechanism shows, for the
first time, that the field decreases by a purely geometric factor $\sin^{-7/2}
\theta_{\rm P,i}$ before freezing to an asymptotic value, where $ \theta_{\rm
P,i}$ is the initial angular width of the polar cap. If $ \theta_{\rm P,i}$
lies in the range $5^o$--$10^o$, then the magnetic field diminution factor
turns out to be $\sim 10^3$--$10^4$ in conformity with observational data.


title: Turbulent Structure of the Interstellar Medium

abstract:
  How does turbulence contribute to the formation and structure of the dense
interstellar medium (ISM)? Molecular clouds are dense, high-pressure objects.
It is usually argued that gravitational confinement causes the high pressures,
and that the clouds are (magneto)hydrostaticobjects supported by a balance
between magnetic and turbulent pressures and gravity. However, magnetic
pressures appear too weak, and MHD turbulent support not only requires driving,
but also results in continuing gravitational collapse, as has now been
demonstrated in simulations reaching 512^3 zones. Models of supernova-driven,
magnetized turbulence readily form transient, high-pressure, dense regions that
may form molecular clouds. They are contained not by self-gravity, but by
turbulent ram pressures from the larger flow. Apparent virialization may
actually be a geometrical effect. Turbulent clouds are unlikely to be in
hydrostatic equilibrium, instead either collapsing or expanding, although they
may appear well-fit by projected equilibrium Bonnor-Ebert spheres. Collapsing
clouds probably form stars efficiently, while expanding ones can still form
stars by turbulent compression, but rather inefficiently.


title: A new paradigm for the universe

abstract:
  This book provides a completely new approach to understanding the universe.
The main idea is that the principal objects in the universe form a spectrum
unified by the presence of a massive or hypermassive black hole. These objects
are variously called quasars, active galaxies and spiral galaxies. The key to
understanding their dynamics is angular momentum and the key tool, and main
innovative idea of this work, is a proper formulation of "Mach's principle"
using Sciama's ideas. In essence, what is provided here is a totally new
paradigm for the universe. In this paradigm, there is no big bang, and the
universe is many orders of magnitude older than current estimates for its age.
Indeed there is no natural limit for its age.


title: Searching for signs of triggered star formation toward IC 1848

abstract:
  We have carried out an in-depth study of three bright-rimmed clouds SFO 11,
SFO 11NE and SFO 11E associated with the HII region IC 1848, using observations
carried out at the James Clerk Maxwell Telescope (JCMT) and the Nordic Optical
Telescope (NOT), plus archival data from IRAS, 2MASS and the NVSS. We show that
the overall morphology of the clouds is reasonably consistent with that of
radiative-driven implosion (RDI) models developed to predict the evolution of
cometary globules. There is evidence for a photoevaporated flow from the
surface of each cloud and, based upon the morphology and pressure balance of
the clouds, it is possible that D-critical ionisation fronts are propagating
into the molecular gas. The primary O star responsible for ionising the
surfaces of the clouds is the 06V star HD17505. Each cloud is associated with
either recent or ongoing star formation: we have detected 8 sub-mm cores which
possess the hallmarks of protostellar cores and identify YSO candidates from
2MASS data. We infer the past and future evolution of the clouds and
demonstrate via a simple pressure-based argument that the UV illumination may
have induced the collapse of the dense molecular cores found at the head of SFO
11 and SFO 11E.


title: Variability in black hole accretion discs

abstract:
  Observations of accreting systems often show significant variability (10-20
percent of accretion luminosity) on timescales much longer than expected for
the disc regions releasing most of the luminosity. We propose an explicit
physical model for disc variability, consistent with Lyubarskii's (1997)
general scheme for solving this problem. We suggest that local dynamo processes
can affect the evolution of an accretion disc by driving angular momentum loss
in the form of an outflow (a wind or jet). We model the dynamo as a small-scale
stochastic phenomenon, operating on roughly the local dynamical timescale. We
argue that large-scale outflow can only occur when the small-scale random
processes in neighbouring disc annuli give rise by chance to a coherent
large-scale magnetic field. This occurs on much longer timescales, and causes a
bright large-amplitude flare as a wide range of disc radii evolve in a coherent
fashion. Most of the time, dynamo action instead produces small-amplitude
flickering. We reproduce power spectra similar to those observed, including a
1/f power spectrum below a break frequency given by the magnetic alignment
timescale at the inner disc edge. However the relation between the black hole
mass and the value of the break frequency is less straightforward than often
assumed in the literature. The effect of an outer disc edge is to flatten the
spectrum below the magnetic alignment frequency there. We also find a
correlation between the variability amplitude and luminosity, similar to that
found in some AGN.


title: Strong Limits on the Infrared Spectrum of HD 209458 b Near 2.2 Micron

abstract:
  We present a brief summary of observations of the transiting extrasolar
planet, HD 209458 b, designed to detect the secondary eclipse. We employ the
method of `occultation spectroscopy', which searches in combined light (star
and planet) for the disappearance and reappearance of weak infrared spectral
features due to the planet as it passes behind the star and reappears. We have
searched for a continuum peak near 2.2 micron (defined by CO and H2O absorption
bands), as predicted by some models of the planetary atmosphere to be
approximately 6E-4 of the stellar flux, but no such peak is detected at a level
of about 3E-4 of the stellar flux. Our results represent the strongest limits
on the infrared spectrum of the planet to date and carry significant
implications for understanding the planetary atmosphere.


title:
The Relativistic Fe Emission Line in XTE J1650-500 with BeppoSAX:
  Evidence for Black Hole Spin and Light Bending Effects?

abstract:
  We report spectral results from three BeppoSAX observations of the black hole
candidate XTE J1650-500 during its 2001/2002 outburst. We find strong evidence
for the presence of a broad and strongly relativistic Fe emission line. The
line profile indicates an accretion disc extending down to two gravitational
radii (or less) suggesting the presence of a rapidly rotating central Kerr
black hole. Thanks to the broadband spectral coverage of BeppoSAX, we could
analyze the 1.5-200 keV spectra of the three observations and report the
presence of a strong reflection component from the accretion disc, which is
totally consistent with the observed broad Fe emission line. The shape of the
reflection component appears to be affected by the same special and general
relativistic effects that produce the broad Fe line. We study the variation of
the different spectral components from the first to the third observation and
we find that they are well reproduced by a recently proposed light bending
model.


title: First detection of triply-deuterated methanol

abstract:
  We report the first detection of triply-deuterated methanol, with 12 observed
transitions, towards the low-mass protostar IRAS 16293-2422, as well as
multifrequency observations of 13CH3OH, used to derive the column density of
the main isotopomer CH3OH. The derived fractionation ratio [CD3OH]/[CH3OH]
averaged on a 10'' beam is 1.4%. Together with previous CH2DOH and CHD2OH
observations, the present CD3OH observations are consistent with a formation of
methanol on grain surfaces, if the atomic D/H ratio is 0.1 to 0.3 in the
accreting gas. Such a high atomic ratio can be reached in the frame of
gas-phase chemical models including all deuterated isotopomers of H3+.


title: Long Term Variability of Cyg X-1, II. The rms-Flux Relation

abstract:
  We study the long term evolution of the relationship between the root mean
square (rms) variability and flux (the ``rms-flux relation'') for the black
hole Cygnus X-1 as monitored from 1996 to 2003 with the Rossi X-ray Timing
Explorer (RXTE). We confirm earlier results by Uttley & McHardy (2001) of a
linear relationship between rms and flux in the hard state on time scales > 5 s
reflecting in its slope the fractional rms variability. We demonstrate the
perpetuation of the linear rms-flux relation in the soft and the intermediate
state. The existence of a non-zero intercept in the linear rms-flux relation
argues for two lightcurve components, for example, one variable and one
non-variable component, or a possible constant rms component. The relationship
between these two hypothesized components can be described by a fundamental
dependence of slope and intercept at time scales ~< 10 ksec with long term
averages of the flux.


title:
Some empirical estimates of the H2 formation rate in photon-dominated
  regions

abstract:
  We combine recent ISO observations of the vibrational ground state lines of
H2 towards Photon-Dominated Regions (PDRs) with observations of vibrationally
excited states made with ground-based telescopes in order to constrain the
formation rate of H2 on grain surfaces under the physical conditions in the
layers responsible for H2 emission. We use steady state PDR models in order to
examine the sensitivity of different H2 line ratios to the H2 formation rate
Rf. We show that the ratio of the 0-0 S(3) to the 1-0 S(1) line increases with
Rf but that one requires independent estimates of the radiation field incident
upon the PDR and the density in order to infer Rf from the H2 line data. We
confirm the earlier result of Habart et al. (2003) that the H2 formation rate
in regions of moderate excitation such as Oph W, S140 and IC 63 is a factor of
5 times larger than the standard rate inferred from UV observations of diffuse
clouds. On the other hand, towards regions of higher radiation field such as
the Orion Bar and NGC 2023, we derive H2 formation rates consistent with the
standard value. We find also a correlation between the H2 1-0 S(1) line and PAH
emission suggesting that Rf scales with the PAH abundance. With the aim of
explaining these results, we consider some empirical models of the H2 formation
process. Here we consider both formation on big (a~0.1 microns) and small (a~10
Angstroms) grains by either direct recombination from the gas phase or
recombination of physisorbed H atoms with atoms in a chemisorbed site. We
conclude that indirect chemisorption is most promising in PDRs. Moreover small
grains which dominate the total grain surface and spend most of their time at
relatively low temperatures may be the most promising surface for forming H2 in
PDRs.


title: A Compact Array imaging survey of southern bright-rimmed clouds

abstract:
  We have carried out a radio-wavelength imaging survey of 45 bright-rimmed
clouds (BRCs), using the Australia Telescope Compact Array to characterise the
physical properties in their ionised boundary layers. We detected radio
emission from a total of 25 clouds and using a combination of Digitised Sky
Survey and mid-infrared MSX micron images classified the emission into that
associated with the ionised cloud rims, that associated with embedded possible
massive YSOs and that unlikely to be associated with the clouds at all. A total
of 18 clouds display radio emission clearly associated with the cloud rim and
we determine the ionising photon flux illuminating these clouds and the
electron density and pressure of their ionised boundary layers. Using a global
estimate for the interior molecular pressure of these clouds we show that the
majority are likely to be in pressure equilibrium and hence are currently being
shocked by photoionisation-induced shocks. We identify those clouds where the
predicted ionising photon flux is inconsistent with that derived from the
observations and show that either the spectral types of the stars illuminating
the BRCs are earlier than previously thought or that there must be additional
ionising sources within the HII regions. Finally, we identify the radio sources
embedded within the clouds with infrared stellar clusters and show that they
contain late O and early B-type stars, demonstrating that a number of BRCs are
intimately involved with high to intermediate-mass star formation.


title: Fast bars in SB0 galaxies

abstract:
  We measured the bar pattern speed in a sample of 7 SB0 galaxies using the
Tremaine-Weinberg method. This represents the largest sample of galaxies for
which bar pattern speed has been measured this way. All the observed bars are
as rapidly rotating as they can be. We compared this result with recent
high-resolution N-body simulations of bars in cosmologically-motivated dark
matter halos, and conclude that these bars are not located inside centrally
concentrated halos.


title: Iron Emission in z ~ 6 QSOs and its Possible Implications

abstract:
  We have obtained low-resolution near-infrared spectra of five SDSS QSOs at
5.3 < z < 6.3 using the NICMOS instrument of the Hubble Space Telescope. We
find evidence of emission in the Fe II complex centered near 2500 A (rest) in
all five objects. We estimate Fe II / Mg II 2800 A flux ratios comparable to
those measured in QSOs at lower redshifts, which indicate metallicities near or
above the solar level. We discuss the possible implications of this result
assuming the iron enrichment to have been produced mainly in Type Ia
supernovae.


title: Central DM density cuspiness in LSB's: a stellar kinematics approach

abstract:
  We present preliminary results from spectroscopic observations of a sample of
11 low surface brightness galaxies (LSB). We measured the stellar and gaseous
kinematics along their major and minor axes. Such information will allow us to
accurately investigate the dark matter (DM) content within their optical
regions, providing further constraints on the predictions of standard CDM
models. Although dynamical modeling is still in progress, our observations
already show that the derived stellar kinematics is more regular than the
ionized gas one, which often shows evidence for non-circular and asymmetric
motions.


title:
Probing the Redshift Desert Using the Gemini Deep Deep Survey: observing
  galaxy mass assembly at z>1

abstract:
  The aim of the Gemini Deep Deep Survey is to push spectroscopic studies of
complete galaxy samples (both red and blue objects) significantly beyond z=1;
this is the redshift where the current Hubble sequence of ellipticals and
spirals is already extant. In the Universe at z=2 the only currently
spectroscopically confirmed galaxies are blue, star-forming and of fragmented
morphology. Exploring this transition means filling the `redshift desert' 1<z<2
where there is a dearth of spectroscopic measurements. To do this we need to
secure redshifts of the oldest, reddest galaxies (candidate ellipticals) beyond
z>1 which has led us to carry out the longest exposure redshift survey ever
done: 100 ksec spectroscopic MOS exposures with GMOS on Gemini North. We have
developed an implementation of the CCD ``nod & shuffle'' technique to ensure
precise sky-subtraction in these ultra-deep exposures. At the halfway mark the
GDDS now has ~36 galaxies in the redshift desert 1.2<z<2 extending up to z=1.97
and I<24.5 with secure redshifts based on weak rest-frame UV absorption
features complete for both red, old objects and young, blue objects. The peak
epoch of galaxy assembly is now being probed by direct spectroscopic
investigation for the first time. On behalf of the GDDS team I present our
first results on the properties of galaxies in the `redshift desert'.


title: Results from DAMA/NaI and perspectives for DAMA/LIBRA

abstract:
  The about 100 kg highly radiopure NaI(Tl) set-up of the DAMA project
(DAMA/NaI) took data over seven annual cycles up to July 2002 and has achieved
results on various rare processes. Its main aim has actually been the
exploitation of the model independent WIMP annual modulation signature. After
this conference the total exposure, collected during the seven annual cycles,
was released. This cumulative exposure (107731 kg day) has given a model
independent evidence for the presence of a Dark Matter particle component in
the galactic halo at 6.3 sigma C.L.; this main result is summarised here. Some
of the many possible corollary model dependent quests for the candidate
particle are mentioned. At present, after about five years of new developments,
a second generation low background set-up (DAMA/LIBRA with a mass of about 250
kg NaI(Tl)) was built and is taking data since March 2003. New R&D efforts
toward a possible NaI(Tl) ton set-up, we proposed in 1996, have been funded and
started in 2003.


title: HI Clouds Beyond the Galactic Disk

abstract:
  Recent observations in the 21cm line with the Green Bank Telescope have
changed our view of the neutral interstellar medium (ISM) in several ways. The
new data show that in the inner parts of the Milky Way the disk-halo interface
is composed of many discrete HI clouds. The clouds lie in a layer more than one
kpc thick and follow Galactic rotation. Their origin and evolution is unknown.
In the outer Galaxy, the new data show that the high-velocity cloud Complex H
is likely a satellite on a retrograde orbit interacting with some extended
component of the Milky Way's ISM. These observations place new constraints on
models of the ISM and are directly related to the work of Don Cox and Ron
Reynolds.


title: Giant planet formation from disk instability; cooling and heating

abstract:
  We present the results of high resolution SPH simulations of the evolution of
gravitationally unstable protoplanetary disks. We report on calculations in
which the disk is evolved using a locally isothermal or adiabatic equation of
state (with shock heating), and also on new simulations in which cooling and
heating by radiation are explicitly modeled. We find that disks with a minimum
Toomre parameter $< 1.4$ fragment into several gravitationally bound
protoplanets with masses from below to a few Jupiter masses. This is confirmed
also in runs where the disk is given a quiet start, growing gradually in mass
over several orbital times. A cooling time comparable to the orbital time is
needed to achieve fragmentation, for disk masses in the range $0.08-0.1
M_{\odot}$. After about 30 orbital times, merging between the bound
condensations always leads to 2-3 protoplanets on quite eccentric orbits.


title:
A Cosmological Kinetic Theory for the Evolution of Cold Dark Matter
  Halos with Substructure: Quasi-Linear Theory

abstract:
  We present a kinetic theory for the evolution of the phase-space distribution
of dark matter particles in galaxy halos in the presence of a cosmological
spectrum of fluctuations. This theory introduces a new way to model the
formation and evolution of halos, which traditionally have been investigated by
analytic gravitational infall models or numerical N-body methods. Unlike the
collisionless Boltzmann equation, our kinetic equation contains nonzero terms
on the right-hand side arising from stochastic fluctuations in the
gravitational potential due to substructures in the dark matter mass
distribution. Using statistics for constrained Gaussian random fields in
standard cosmological models, we show that our kinetic equation to second-order
in perturbation theory is of the Fokker-Planck form, with one scattering term
representing drift and the other representing diffusion in velocity-space. The
drift is radial, and the drift and diffusion coefficients depend only on
positions and not velocities; our relaxation process in the quasilinear regime
is therefore different from the standard two-body relaxation. We provide
explicit expressions relating these coefficients to the linear power spectrum
of mass fluctuation and present results for the currently favored cold dark
matter model with a nonzero cosmological constant. Solutions to this kinetic
equation will provide a complete description of the cold dark matter spatial
and velocity distributions for the average halo during the early phases of
galaxy halo formation.


title:
A Redshift Determination for XRF 020903: First Spectroscopic
  Observations of an X-Ray Flash

abstract:
  We report the discovery of optical and radio afterglow emission from the
extremely soft X-ray flash, XRF 020903. Our spectroscopic observations provide
the first redshift for an X-ray flash, thereby setting the distance scale for
these events. At $z=0.251$, XRF 020903 is one of the nearest cosmic explosions
ever detected, second only to the recent GRB 030329 and the unusual GRB
980425/SN 1998bw. Moreover, XRF 020903 is the first X-ray flash for which we
detect an optical afterglow. The luminosity of the radio afterglow of XRF
020903 is 1000 times greater than that of Ibc supernovae but similar to those
of GRB afterglows. From broadband afterglow modeling we show that the explosion
energy of XRF 020903 is not dissimilar from values inferred for typical
gamma-ray bursts, suggesting that these cosmological explosions may derive from
a similar mechanism.


title:
On the Xray Luminosity - velocity dispersion relation of groups of
  galaxies

abstract:
  We analyse the Lx-sigma relation for the new Mulchaey et al. group Atlas. We
find that once we take into account the possible statistical bias introduced by
the cutoff in luminosity, we recover a relation which is consistent with that
of clusters, ie., Lx ~ sigma^4. The larger scatter of this relation for groups
of galaxies could be attributed to an orientation effect, due to which the
radial velocity dispersion of groups oriented close to orthogonal to the line
of sight, would be underestimated. This effect could also contribute in the
direction of flattening the slope of the group Lx-sigma relation.


title: The dark matter halos of spheroidal galaxies and clusters of galaxies

abstract:
  We describe the first results from two observational projects aimed at
measuring the amount and spatial distribution of dark matter in distant
early-type galaxies (E/S0s) and clusters of galaxies. At the galaxy scale, the
Lenses Structure and Dynamics (LSD) Survey is gathering kinematic data for
distant (up to $z\sim1$) E/S0s that are gravitational lenses. A joint lensing
and dynamical analysis constrains the fraction of dark matter within the
Einstein radius, the mass-to-light ratio of the stellar component, and the
total slope of the mass density profile. These properties and their evolution
with redshift are briefly discussed in terms of the formation and evolution of
E/S0 galaxies and measurement of the Hubble Constant from gravitational time
delay systems. At the cluster scale -- after careful removal of the stellar
component with a joint lensing and dynamical analysis -- systems with giant
radial arcs can be used to measure precisely the inner slope of the dark matter
halo. An HST search for radial arcs and the analysis of a first sample are
briefly discussed in terms of the universal dark matter halos predicted by CDM
simulations.


title: The Galaxy's Eating Habits

abstract:
  The possibility of a gaseous halo stream which was stripped from the
Sagittarius dwarf galaxy is presented. The total mass of the neutral hydrogen
along the orbit of the Sgr dwarf in the direction of the Galactic anticenter is
4-10 x 10^6 Msun (at 36 kpc, the distance to the stellar debris in this
region). Both the stellar and gaseous components have negative velocities in
this part of the sky, but the gaseous component extends to higher negative
velocities. We suggest this gaseous stream was stripped from the main body of
the dwarf 0.2 - 0.3 Gyr ago during its current orbit after a passage through a
diffuse edge of the Galactic disk with a density > 10^{-4} cm^{-3}. The gas
would then represent the dwarf's last source of star formation fuel and
explains how the galaxy was forming stars 0.5-2 Gyr ago.


title: Graviton Mass from Close White Dwarf Binaries Detectable with LISA

abstract:
  The arrival times of gravitational waves and optical light from orbiting
binaries provide a mechanism to understand the propagation speed of gravity
when compared to that of light or electromagnetic radiation. This is achieved
with a measurement of any offset between optically derived orbital phase
related to that derived from gravitational wave data, at a specified location
of one binary component with respect to the other. Using a sample of close
white dwarf binaries (CWDBs) detectable with the Laser Interferometer Space
Antenna (LISA) and optical light curve data related to binary eclipses from
meter-class telescopes for the same sample, we determine the accuracy to which
orbital phase differences can be extracted. We consider an application of these
measurements involving a variation to the speed of gravity, when compared to
the speed of light, due to a massive graviton. For a subsample of $\sim$ 400
CWDBs with high signal-to-noise gravitational wave and optical data with
magnitudes brighter than 25, the combined upper limit on the graviton mass is
at the level of $\sim 6 \times 10^{-24}$ eV. This limit is two orders of
magnitude better than the present limit derived by Yukawa-correction arguments
related to the Newtonian potential and applied to the Solar-system.


title:
Sloan Digital Sky Survey Spectroscopic Lens Search. I. Discovery of
  Intermediate-Redshift Star-Forming Galaxies Behind Foreground Luminous Red
  Galaxies

abstract:
  We present a catalog of 49 spectroscopic strong gravitational lens candidates
selected from a Sloan Digital Sky Survey sample of 50996 luminous red galaxies.
Potentially lensed star-forming galaxies are detected through the presence of
background oxygen and hydrogen nebular emission lines in the spectra of these
massive foreground galaxies. This multiline selection eliminates the ambiguity
of single-line identification and provides a very promising sample of candidate
galaxy-galaxy lens systems at low to intermediate redshift, with foreground
redshifts ranging from 0.16 to 0.49 and background redshifts from 0.25 to 0.81.
Any lenses confirmed within our sample would be important new probes of
early-type galaxy mass distributions, providing complementary constraints to
those obtained from currently known lensed high-redshift quasars.


title:
Constraints on Chaplygin quartessence from the CLASS gravitational lens
  statistics and supernova data

abstract:
  The nature of the dark components (dark matter and dark energy) that dominate
the current cosmic evolution is a completely open question at present. In
reality, we do not even know if they really constitute two separated
substances. In this paper we use the recent Cosmic All Sky Survey (CLASS)
lensing sample to test the predictions of one of the candidates for a unified
dark matter/energy scenario, the so-called generalized Chaplygin gas (Cg) which
is parametrized by an equation of state $p = -A/\rho_{Cg}^{\alpha}$ where $A$
and $\alpha$ are arbitrary constants. We show that, although the model is in
good agreement with this radio source gravitational lensing sample, the limits
obtained from CLASS statistics are only marginally compatible with the ones
obtained from other cosmological tests. We also investigate the constraints on
the free parameters of the model from a joint analysis between CLASS and
supernova data.


title: Launching of resistive magnetic protostellar jets

abstract:
  Turbulent accretion disks are the most probable origin of jets from young
stellar objects. Using an extended version of ZEUS-3D code in the axisymmetry
option we investigate the evolution of a disk wind into a collimated jet.
Resistive jets propagate slower with increasing magnetic diffusivity, and the
degree of collimation decreases. The resistive disk included in the simulations
ejects persistent, well collimated jet.


title: ANNz: estimating photometric redshifts using artificial neural networks

abstract:
  We introduce ANNz, a freely available software package for photometric
redshift estimation using Artificial Neural Networks. ANNz learns the relation
between photometry and redshift from an appropriate training set of galaxies
for which the redshift is already known. Where a large and representative
training set is available ANNz is a highly competitive tool when compared with
traditional template-fitting methods.
  The ANNz package is demonstrated on the Sloan Digital Sky Survey Data Release
1, and for this particular data set the r.m.s. redshift error in the range 0 <
z < 0.7 is 0.023. Non-ideal conditions (spectroscopic sets which are small, or
which are brighter than the photometric set for which redshifts are required)
are simulated and the impact on the photometric redshift accuracy assessed.


title: Polarized CMB: Reionization and Primordial Tensor modes

abstract:
  We discuss upcoming opportunities with cosmic microwave background (CMB)
observations during the post-WMAP era. The curl-modes of CMB polarization probe
inflationary gravitational waves (IGWs). While a significant source of
confusion is expected from cosmic shear conversion of polarization related to
density perturbations, higher resolution observations of CMB anisotropies can
be used for a lensing reconstruction and to separate gravitational-wave
polarization signature from that of lensing. Separations based on current
lensing reconstruction techniques allow the possibility to probe inflationary
energy scales below 10^15 GeV in a range that includes grand unified theories.
The observational detection of primordial curl-modes is aided by rescattering
at late times during the reionized epoch with optical depth to electron
scattering at the level of 0.1 and above. An improved measurement of this
optical depth is useful to optimize experimental parameters of a post-WMAP
mission attempting to target the IGW background.


title:
The physical properties of star forming galaxies in the low redshift
  universe

abstract:
  (modified) We present a comprehensive study of the physical properties of
\~10^5 galaxies with measurable star formation in the SDSS. By comparing
physical information extracted from the emission lines with continuum
properties, we build up a picture of the nature of star-forming galaxies at
z<0.2. We take out essentially all aperture bias using resolved imaging,
allowing an accurate estimate of the total SFRs in galaxies. We determine the
SFR density to be 1.915^{+0.02}_{-0.01}(rand.)^{+0.14}_{-0.42} (sys.) h70
10^{-2} Msun/yr/Mpc^3 at z=0.1 (for a Kroupa IMF) and we study the distribution
of star formation as a function of various physical parameters. The majority of
the star formation in the low redshift universe takes place in moderately
massive galaxies (10^10-10^11 Msun), typically in HSB disk galaxies. Roughly
15% of all star formation takes place in galaxies that show some sign of an
active nucleus. About 20% occurs in starburst galaxies. We show that the
present to past-average star formation rate, the Scalo b-parameter; is almost
constant over almost three orders of magnitude in mass, declining only at
M*>10^10 Msun. The volume averaged b parameter is 0.408^{+0.005}_{-0.002}
(rand).^{+0.029}_{-0.090} (sys.) h70^{-1}. We use this value constrain the star
formation history of the universe. In agreement with other work we find a
correlation between $b$ and morphological type, as well as a tight correlation
between the 4000AA break (D4000) and b. We discuss how D4000 can be used to
estimate b parameters for high redshift galaxies.