title: The influence of binaries on galactic chemical evolution

abstract:
  Understanding the galaxy in which we live is one of the great intellectual
challenges facing modern science. With the advent of high quality observational
data, the chemical evolution modeling of our galaxy has been the subject of
numerous studies in the last years. However, all these studies have one missing
element which is the evolution of close binaries. Reason: their evolution is
very complex and single stars only perhaps can do the job. (Un)Fortunately at
present we know that the majority of the observed stars are members of a binary
or multiple system and that certain objects can only be formed through binary
evolution. Therefore galactic studies that do not account for close binary
evolution may be far from realistic.
  Because of the large expertise developed through the years in stellar
evolution in general and binary evolution in particular at the Brussels
Astrophysical Institute, we found ourselves in a privileged position to be the
first to do chemical evolutionary simulations with the inclusion of detailed
binary evolution. The complexity of close binary evolution has kept many
astronomers from including binary stars into their studies. However, it is not
always the easiest way of living that gives you the most excitement and
satisfaction.


title: X-ray to UV Variability Correlation in MCG-6-30-15

abstract:
  We used a ~300 ks long XMM-Newton observation of the Seyfert 1 galaxy
MCG-6-30-15 to study the correlation between the 0.2-10 keV X-ray and the
3000-4000 A bands. We found a significant correlation peak at a time lag of 160
ks where the UV flux variations preceded the variations in the X-ray band. We
interpret this result as evidence in favour of Comptonisation models where the
observed X-rays are produced through Compton up-scattering of thermal UV seed
photons from an accretion disc, as this process naturally predicts the UV
variations to precede similar flux variations in the X-rays. The length of the
time lag favours models where the observed UV and the seed-photon-emitting
regions are connected by perturbations of the accretion flow traveling inwards
through the disc, affecting first the main U-band-emitting radii and then the
innermost region where the bulk of the seed photons is expected to be produced.
Finally, the absence of significant features in the correlation function with
X-ray flux variations preceding those in the UV indicates that the observed
U-band photons are not mainly produced through reprocessing of hard X-rays in
this source.


title: Kinematics of stars and brown dwarfs at birth

abstract:
  We use numerical N-body simulations in order to test whether the kinematics
of stars and brown dwarfs at birth depend on mass. In particular we examine how
initial variations in velocity dispersion can affect the spatial distribution
of stellar and substellar objects in clusters. We use 'toy' N-body models of a
Pleiades-like cluster in which brown dwarfs have their own velocity dispersion
sigma_(V_BD) which is k times larger than the stellar one.
  We find that in order to match the broad agreement between the brown dwarf
fraction in the field and in the Pleiades, the velocity dispersion of brown
dwarfs at birth has to be less than twice the stellar velocity dispersion, i.e.
cannot exceed a few km/s in the Pleiades cluster. In order to discern more
subtle differences between the kinematics of brown dwarfs and stars at birth,
our simulations show that we need to look at clusters that are much less
dynamically evolved than the Pleiades. One might especially seek evidence of
high velocity brown dwarfs at birth by examining spatial distribution of stars
and brown darfs in clusters that are about a crossing timescale old.


title:
Organic Molecules in Low-Mass Protostellar Hot Cores: Submillimeter
  Imaging of IRAS 16293-2422

abstract:
  Arcsecond-resolution spectral observations toward the protobinary system IRAS
16293-2422 at 344 and 354 GHz were conducted using the Submillimeter Array.
Complex organic molecules such as CH3OH and HCOOCH3 were detected. Together
with the rich organic inventory revealed, it clearly indicates the existence of
two, rather than one, compact hot molecular cores (smaller than or equal to 400
AU in radius) associated with each of the protobinary components identified by
their dust continuum emission in the inner star-forming core.


title: Intracluster and Intragroup Entropy from Quasar Activity

abstract:
  We investigate how the hierarchical merging of dark matter halos, the
radiative cooling of baryons, and the energy feedback from supernovae and
active galactic nuclei or quasars combine to govern the amount and the thermal
state of the hot plasma pervading groups and clusters of galaxies. We show
that, by itself, supernova preheating of the external gas flowing into clusters
falls short of explaining the observed X-ray scaling relations of the plasma
luminosity L_X or the plasma entropy K versus the X-ray temperature T. To
account for the scaling laws from rich to poor clusters takes preheating
enhanced by the energy input from active galactic nuclei. In groups, on the
other hand, the internal impacts of powerful quasars going off in member
galaxies can blow some plasma out of the structure. So they depress L_X and
raise K to the observed average levels; meanwhile, the sporadic nature of such
impulsive events generates the intrinsic component of the wide scatter apparent
in the data. The same quasar feedback gives rise in groups to entropy profiles
as steep as observed, a feature hard to explain with simple preheating schemes.
Finally, we argue a close connection of the L_X-T or the K-T relation with the
M_{\bullet}-\sigma correlation between the host velocity dispersion and the
masses of the black holes, relics of the quasar activity.


title:
Detecting cold H2 globules in the outer Galactic disc by microlensing
  towards the Maffei 1 elliptical

abstract:
  A serious candidate for dark matter in spiral galaxies are cold molecular
hydrogen globules with a condensed central core and a disc-like space
distribution probably similar to that of neutral hydrogen. This paper shows
that the H_2 cores are sufficiently compact and massive to be detected by
microlensing in the outer Galactic disc and that the Maffei 1 elliptical
galaxy, at a distance of 3 Mpc and Galactic latitude b=-0.6 deg, offers an
ideal target for such an experiment. The microlensing optical depth of H_2
cores along the line of sight to this galaxy is estimated to tau~0.7x10^(-6) if
most of the dark mass in the Milky Way resides in such cores, and the typical
event timescale to ~< 1 day. Detection rates are computed both in the classical
and pixel lensing approaches in the I- and K-bands, and for a representative
selection of existing observing facilities. In the more efficient pixel lensing
case, two 10-hour observing runs, separated in time by at least several days,
should yield of order 10 positive detections at the 5-sigma level using
ground-based 8m-class telescopes in the K-band or the Hubble Space Telescope
ACS camera in the I-band, and the corresponding fraction of events with
timescale measurable to an accuracy better than 50% amounts to about 9% and 4%
respectively for these observing alternatives.


title: Testing a string dilaton model with experimental and observational data

abstract:
  We test the prediction of the time variation of the fine structure constant
in the string dilaton model proposed by Damour and Polyakov. First, we analize
the dependence of all available observational and experimental data with the
fine structure constant variation. Furthermore, we obtain the prediction of the
time variation of the fine structure constant including the renormalization
group correction. Finally, we use the data set to perform a statistical
analyisis. This analysis enables us to determine that the the dilaton model is
in agreement with most of the data. Finally, constraints on the free parameters
of this model are obtained.


title: The Cosmology of Generalized Modified Gravity Models

abstract:
  We consider general curvature-invariant modifications of the Einstein-Hilbert
action that become important only in regions of extremely low space-time
curvature. We investigate the far future evolution of the universe in such
models, examining the possibilities for cosmic acceleration and other ultimate
destinies. The models generically possess de Sitter space as an unstable
solution and exhibit an interesting set of attractor solutions which, in some
cases, provide alternatives to dark energy models.


title:
The Evolution of Cosmic Magnetic Fields: From the Very Early Universe,
  to Recombination, to the Present

abstract:
  (abridged) A detailed examination of the evolution of stochastic magnetic
fields between high cosmic temperatures and the present epoch is presented. A
simple analytical model matching the results of the 3D MHD simulations allows
for the prediction of present day magnetic field correlation lengths and
energy. Our conclusions are multi fold. (a) Initial primordial fields with only
a small amount of helicity are evolving into maximally helical fields. (b)
There exists a correlation between the strength of the magnetic field, B, at
the peak of it's spectrum and the location of the peak, given at the present
epoch by: B ~ 5x10^{-12} (L/kpc) Gauss, where L is the correlation length
determined by the initial magnetic field. (c) Concerning studies of generation
of cosmic microwave background (CMBR) anisotropies due to primordial magnetic
fields of B~10^{-9} Gauss on ~ 10 Mpc scales, such fields are not only
impossible to generate in early causal magnetogenesis scenarios but also
seemingly ruled out by distortions of the CMBR spectrum due to magnetic field
dissipation on smaller scales and the overproduction of cluster magnetic
fields. (d) The most promising detection possibility of CMBR distortions due to
primordial magnetic fields may be on much smaller scales at higher multipoles
l~10^6 where the signal is predicted to be the strongest. (e) It seems possible
that magnetic fields in clusters of galaxies are entirely of primordial origin,
without invoking dynamo amplification. Such fields would be of (pre-collapse)
strength 10^{-12} - 10^{-11} Gauss with correlation lengths in the kpc range,
and would also exist in voids of galaxies.


title:
Deuterated molecular hydrogen in the Galactic ISM. New observations
  along seven translucent sightlines

abstract:
  We present column density measurements of the HD molecule in the interstellar
gas toward 17 Galactic stars. The values for the seven most heavily reddened
sightlines, with E(B-V) = 0.38-0.72, are derived from observations with the Far
Ultraviolet Spectroscopic Explorer (FUSE). The other ten values are from a
reanalysis of spectra obtained with Copernicus. In all cases, high-resolution
ground-based observations of KI and/or the CH molecule were used to constrain
the gas velocity structure and to correct for saturation effects. Comparisons
of the column densities HD, CH, CN, and KI in these 17 sightlines indicate that
HD is most tightly correlated with CH. Stringent lower limits to the
interstellar D/H ratio, derived from the HD/2H2 ratio, range from 3.7 10^(-7)
to 4.3 10^(-6). Our results also suggest that the HD/H2 ratio increases with
the molecular fraction f(H2) and that the interstellar D/H ratio might be
obtained from HD by probing clouds with f(H2) = 1. Finally, we note an apparent
relationship between the molecular fractions of hydrogen and deuterium.


title:
Current Results from the RRFID Kinematic Survey: Apparent Speeds from
  the First Five Years of Data

abstract:
  We present current results from our ongoing project to study the parsec-scale
relativistic jet kinematics of sources in the U.S. Naval Observatory's Radio
Reference Frame Image Database (RRFID). The RRFID consists of snapshot
observations using the VLBA plus up to 9 additional antennas at 8 and 2 GHz.
The Image Database currently contains about 3000 images of 450 sources from
1994 to 2004, with some sources having images at 20 epochs or more. We have now
completed analysis of the 8 GHz images for all sources observed at 3 or more
epochs from 1994 to 1998. The completed analysis comprises 966 images of 87
sources, or an average of 11 epochs per source. Apparent jet speeds have been
measured for these sources, and the resulting speed distribution has been
compared with results obtained by other large VLBI surveys. The measured
apparent speed distribution agrees with those found by the 2 cm survey and
Caltech-Jodrell Bank (CJ) survey; however, when a source-by-source comparison
is done with the 2 cm survey results, significant disagreement is found in the
apparent speed measurements for a number of sources. This disagreement can be
traced in most cases to either an insufficient time baseline for the current
RRFID results, or to apparent component mis-identification in the 2 cm survey
results caused by insufficient time sampling. These results emphasize the need
for long time baselines and dense time sampling for multi-epoch monitoring of
relativistic jets.


title: Extra-planar Diffuse Hot Gas Around Normal Disk Galaxies

abstract:
  I review results from {\sl Chandra} observations of nearby normal edge-on
galaxies (Sd to Sa types). These galaxies have a broad range of star formation
rate, but none of them is dominated by a nuclear starburst. The galaxies are
all in directions of low Galactic foreground absorption. Extra-Planar diffuse
soft X-ray emission is detected unambiguously from all the galaxies, except for
N4244 (Sd), which is low in both the stellar mass and the star formation rate.
The thermal nature of the X-ray-emitting gas is well established, although its
chemical and ionization states remain largely uncertain. The X-ray luminosity
of the gas is proportional to the star formation rate and to the stellar mass
of the galaxies. But the luminosity accounts for at most a few percent of the
expected supernova mechanical energy input. Therefore, there is a ``missing''
energy problem for spiral galaxies. Much of the energy in late-type spirals may
be converted and radiated in lower energy bands. But early-type ones most
likely have outflows, which are powered primarily by Type Ia supernovae in
galactic bulges. These galactic outflows may strongly affect both the dynamics
and cooling of the intergalactic gas accretion, hence the evolution of the
galaxies.


title: Three Years of ChaMPlane Northern Field WIYN Spectroscopy

abstract:
  We present initial results of WIYN spectroscopic observations of selected
objects detected in the Chandra Multiwavelength Plane (ChaMPlane) Survey in
fields towards the Galactic anti-center. ChaMPlane is designed to identify low
luminosity X-ray sources, both accretion-powered and stellar coronal, in the
Galaxy. It also includes a wider-fields optical imaging Survey conducted with
the NOAO Mosaic cameras to identify optical counterparts as well as H
alpha-selected objects in the ~5 times larger field. We report spectra for 1048
objects in galactic anti-center (i.e. northern) fields, resulting in 609 type
determinations. These include 5 new cataclysmic variables, 4 Be stars, 14
lithium-absorption stars, 180 stellar coronal sources (primarily dMe stars),
and 29 new quasars. Bright optical counterparts of Chandra sources in this
sample are most frequently dMe stars whereas a majority of the faintest (R ~21)
spectroscopically classified Chandra source counterparts are quasars. The bulk
of H alpha-selected sources appears to be roughly evenly divided between dMe
stars and M stars at all magnitudes.


title:
Monster Redshift Surveys through Dispersive Slitless Imaging: The Baryon
  Oscillation Probe

abstract:
  Wide-field imaging from space should not forget the dispersive dimension. We
consider the capability of space-based imaging with a slitless grism: because
of the low near-infrared background in space and the high sky-density of high
redshift emission line galaxies this makes for a very powerful redshift machine
with no moving parts. A small 1m space telescope with a 0.5 degree field of
view could measure redshifts for 10^7 galaxies at 0.5<z<2 per year, this is a
MIDEX class concept which we have dubbed `The Baryon Oscillation Probe' as the
primary science case would be constraining dark energy evolution via
measurement of the baryonic oscillations in the galaxy power spectrum. These
ideas are generalizable to other missions such as SNAP and DESTINY.


abstract:
  The cosmological utility of type Ia Supernovae (SNe) prompted numerous
studies of these events, and they are now well characterized observationally,
both as individual objects and as a population. In contrast, all other types of
SNe (i.e., core-collapse events) are not as well observationally characterized.
While some individual events have been studied in great detail (e.g., SN 1987A
or SN 1998bw), the global properties of the core-collapse SN population are
little known. However, in recent years, major drivers for change have emerged,
among them the verification of the connection between core-collapse SNe and
long-duration Gamma-Ray Bursts (GRBs), the possible utility of some
core-collapse SNe (type II-P) as independent cosmological probes, and studies
of core-collapse SNe as high redshift targets for missions like SNAP and JWST.
The Caltech Core-Collapse Project (CCCP) is a large observational program using
the Hale 200'' and the robotic 60'' telescopes at Palomar observatory to obtain
optical photometry, spectroscopy and IR photometry of ~50 nearby core-collapse
SNe. The program is designed to provide a complete sample of core-collapse
events, with well-defined selection criteria and uniform, high-quality
optical/IR observations, as well as radio and X-ray light curves for some
events. We will use this sample to characterize the little-studied properties
of core-collapse SNe as a population. The sample will be used as a comparison
set for studies of SNe associated with Gamma-Ray Bursts, to promote and
calibrate the use of SNe II-P for cosmography, and to set the stage for
investigations of SNe at high-z using coming space missions such as SNAP and
JWST.


title: Spatially Resolved Chemistry in Nearby Galaxies I. The Center of IC 342

abstract:
  We have imaged emission from the millimeter lines of eight molecules--C2H,
C34S, N2H+, CH3OH, HNCO, HNC, HC3N, and SO--in the central half kpc of the
nearby spiral galaxy IC 342. The 5" (~50 pc) resolution images were made with
OVRO. Using these maps we obtain a picture of the chemistry within the nuclear
region on the sizescales of individual GMCs. Bright emission is detected from
all but SO. There are marked differences in morphology for the different
molecules. A principal component analysis is performed to quantify similarities
and differences among the images. This analysis reveals that while all
molecules are to zeroth order correlated, that is, they are all found in dense
molecular clouds, there are three distinct groups of molecules distinguished by
the location of their emission within the nuclear region. N2H+, C18O, HNC and
HCN are widespread and bright, good overall tracers of dense molecular gas. C2H
and C34S, tracers of PDR chemistry, originate exclusively from the central
50-100 pc region, where radiation fields are high. The third group of
molecules, CH3OH and HNCO, correlates well with the expected locations of
bar-induced orbital shocks. The good correlation of HNCO with the established
shock tracer molecule CH3OH is evidence that this molecule, whose chemistry has
been uncertain, is indeed produced by processing of grains. HC3N is observed to
correlate tightly with 3mm continuum emission, demonstrating that the young
starbursts are the sites of the warmest and densest molecular gas. We compare
our HNC images with the HCN images of Downes et al. (1992) to produce the first
high resolution, extragalactic HCN/HNC map: the HNC/HCN ratio is near unity
across the nucleus and the correlation of both of these gas tracers with the
star formation is excellent. (Abridged).


title: Development of Uniform CdTe Pixel Detectors Based on Caltech ASIC

abstract:
  We have developed a large CdTe pixel detector with dimensions of 23.7 x 13.0
mm and a pixel size of 448 x 448 um^2. The detector is based on recent
technologies of an uniform CdTe single crystal, a two-dimensional ASIC, and
stud bump-bonding to connect pixel electrodes on the CdTe surface to the ASIC.
Good spectra are obtained from 1051 pixels out of total 1056 pixels. When we
operate the detector at -50 C, the energy resolution is 0.67 keV and 0.99 keV
at 14 keV and 60 keV, respectively. Week-long stability of the detector is
confirmed at operating temperatures of both -50 C and -20 C. The detector also
shows high uniformity: the peak positions for all pixels agree to within 0.82%,
and the average of the energy resolution is 1.04 keV at a temperature of -50 C.
When we normalized the peak area by the total counts detected by each pixel, a
variation of 2.1 % is obtained.


title:
Gravitational Collapse in an Expanding Universe: Scaling Relations for
  Two-Dimensional Collapse Revisited

abstract:
  We investigate non-linear scaling relations for two-dimensional gravitational
collapse in an expanding background using a 2D TreePM code and study the
strongly non-linear regime ($\bar\xi \leq 200$) for power law models. Evolution
of these models is found to be scale-invariant in all our simulations. We find
that the stable clustering limit is not reached, but there is a model
independent non-linear scaling relation in the asymptotic regime. This confirms
results from an earlier study which only probed the mildly non-linear regime
($\bar\xi \leq 40$). The correlation function in the extremely non-linear
regime is a less steep function of scale than reported in earlier studies. We
show that this is due to coherent transverse motions in massive haloes. We also
study density profiles and find that the scatter in the inner and outer slopes
is large and that there is no single universal profile that fits all cases. We
find that the difference in typical density profiles for different models is
smaller than expected from similarity solutions for halo profiles and
transverse motions induced by substructure are a likely reason for this
difference being small.


title: Discovery of magnetic fields in hot subdwarfs

abstract:
  We present initial results of a project to measure mean longitudinal magnetic
fields in a group of sdB/OB/O stars. The project was inspired by the discovery
of three super-metal-rich sdOB stars, each having metals (e.g. Ti, V) enhanced
by factors of 10^3 to 10^5. Similar behaviour is observed in chemically
peculiar A stars, where strong magnetic fields are responsible for the
enrichment. With this in mind, we obtained circularly polarised spectra of two
of the super-metal-rich sdOBs, two "normal" sdBs and two sdOs using FORS1 on
the ESO/VLT. By examining circular polarisation in the hydrogen Balmer lines
and in helium lines, we have detected magnetic fields with strengths of 1-2 kG
in most of our targets. This suggests that such fields are relatively common in
hot subdwarfs.


title:
Excitation rates of p modes: mass luminosity relation across the HR
  diagram

abstract:
  We compute the rates P at which energy is injected into the p modes for a set
of 3D simulations of outer layers of stars.
  We found that Pmax - the maximum in P - scales as (L/M)^s where s is the
slope of the power law, L and M are the luminosity and the mass of the 1D
stellar models associated with the simulations. The slope is found to depend
significantly on the adopted representation for the turbulent eddy-time
correlation function, chi_k. According to the expected performances of COROT,
it will likely be possible to measure Pmax as a function of L/M and to
constrain the properties of stellar turbulence as the turbulent eddy
time-correlation.


title:
Which are the youngest protostars? Determining properties of confirmed
  and candidate Class0 sources by broad-band photometry

abstract:
  We searched the literature to obtain a complete list of known Class0 sources.
A list of 95 confirmed or candidate objects was compiled. To the best of our
knowledge, all published broad-band observations from 1mu to 3.5mm have been
collected and are assembled in a catalogue. These data were used to determine
physical properties (T_bol, L_bol, L_smm/L_bol, M_env) and for a uniform
classification. 50 sources possess sufficient observational data and are
classified as Class0 or Class0/1 objects. The source properties are compared
with different evolutionary models to infer ages and masses, and their
correlations are investigated. About 25% of the sources are found to be in a
quiet accretion phase or possess a significantly different time evolution of
the accretion rate than the average. In Taurus, with its isolated star
formation mode, this seems especially to be the case.


title: The Dynamic Radio Sky

abstract:
  Transient radio sources are necessarily compact and usually are the locations
of explosive or dynamic events, therefore offering unique opportunities for
probing fundamental physics and astrophysics. In addition, short-duration
transients are powerful probes of intervening media owing to dispersion,
scattering and Faraday rotation that modify the signals. While radio astronomy
has an impressive record obtaining high time resolution, usually it is achieved
in quite narrow fields of view. Consequently, the dynamic radio sky is poorly
sampled, in contrast to the situation in the X-ray and gamma-ray bands. The SKA
has the potential to change this situation, opening up new parameter space in
the search for radio transients. We summarize the wide variety of known and
hypothesized radio transients and demonstrate that the SKA offers considerable
power in exploring this parameter space. Requirements on the SKA to search the
parameter space include the abilities to (1) Make targeted searches using
beamforming capability; (2) Conduct blind, all-sky surveys with dense sampling
of the frequency-time plane in wide fields; (3) Sample the sky with multiple
fields of view from spatially well-separated sites in order to discriminate
celestial and terrestrial signals; (4) Utilize as much of the SKA's aggregate
collecting area as possible in blind surveys, thus requiring a centrally
condensed configuration; and (5) Localize repeating transient sources to high
angular precision, requiring a configuration with long baselines, thus
requiring collecting area in both a centrally condensed "core" array and
sufficient area on long baselines.


title: Formation and Evolution of Very Low Mass Stars and Brown Dwarfs

abstract:
  The formation and evolution of brown dwarfs are currently "hot topics" in
cool star research. Latest observations and modeling efforts on disks,
accretion, outflows, spatial distribution, and binarity in the context of the
formation by ejection model and alternative scenarios were presented and
discussed vigorously in this splinter session. A second major topic was
rotation and activity of these objects. This part included observations of
rotation periods and amplitudes, variability, and X-ray activity, and their
consequences for the generation of magnetic fields and the cool atmospheres.


title: Rotational evolution of very low mass objects and brown dwarfs

abstract:
  The regulation of angular momentum is one of the key processes for our
understanding of stellar evolution. The rotational evolution of solar-mass
stars is mainly determined by the magnetic interaction with their circumstellar
disk and angular momentum loss through stellar winds, and In contrast to
solar-mass stars, very low mass (VLM) objects and brown dwarfs are believed to
be fully convective. This may lead to major differences of rotation and
activity, since fully convective objects may not host a solar-type dynamo.
Here, we report on our observational efforts to understand the rotational
evolution of VLM objects. By means of photometric monitoring, we determined 62
rotation periods for targets in three clusters, which form an age sequence from
3 to 125 Myr. We find that VLM objects rotate faster than their solar-mass
siblings in all evolutionary stages. Their rotational evolution seems to be
determined by hydrostatic contraction and exponential angular momentum loss.
The photometric amplitudes of the light curves are much lower than for
solar-mass stars. This may be explained as a consequence of smaller spot
coverage, more symmetric spot distributions, or lower contrast between spots
and their environment. Most of these results can be explained with a change of
the magnetic field properties with decreasing mass. VLM objects possibly
possess only small-scale, turbulent magnetic fields.


title:
The Evolution of Substructure in Galaxy, Group and Cluster Haloes II:
  Global Properties

abstract:
  In a previous paper, we described a new method for including detailed
information about substructure in semi-analytic models of dark matter halo
formation based on merger trees. In this paper, we present the basic
predictions of our full model of halo formation. We first describe the overall
properties of substructure in galaxy, group or cluster haloes at the present
day. We then discuss the evolution of substructure, and the effect of the mass
accretion history of an individual halo on the mass function and orbital
grouping of its subhalo population. We show, in particular, that the shape of
the subhalo mass function is strongly correlated with the formation epoch of
the halo. In a third paper in this series we will compare the results of our
semi-analytic method with the results of self-consistent numerical simulations
of halo formation.


title:
The Evolution of Substructure in Galaxy, Group and Cluster Haloes III:
  Comparison with Simulations

abstract:
  In a previous paper, we described a new method for including detailed
information about substructure in semi-analytic models of halo formation based
on merger trees. In this paper, we compare the predictions of our model with
results from self-consistent numerical simulations. We find that in general the
two methods agree extremely well, particularly once numerical effects and
selection effects in the choice of haloes are taken into account. As expected
from the original analyses of the simulations, we see some evidence for
artificial overmerging in the innermost regions of the simulated haloes, either
because substructure is being disrupted artificially or because the
group-finding algorithms used to identify substructure are not detecting all
the bound clumps in the highest-density regions. Our analytic results suggest
that greater mass and force resolution may be required before numerical
overmerging becomes negligible in all current applications. We discuss the
implications of this result for observational and experimental tests of halo
substructure, such as the analysis of discrepant magnification ratios in
strongly lensed systems, terrestrial experiments to detect dark matter
particles directly, or indirect detection experiments searching for positrons,
gamma-rays, neutrinos or other dark matter decay products.


title: Optical and GeV-TeV flashes from gamma-ray bursts

abstract:
  The synchrotron optical flash caught in GRB 990123 overlaps with the MeV
radiation front, and the optical-emitting electrons must also produce GeV-TeV
emission by inverse Compton scattering of MeV photons. The ultra-high-energy
flash can be much stronger than its optical counterpart. We also note that
Compton cooling by MeV photons immediately terminates the optical emission
unless the fireball Lorentz factor exceeds 10^3. Severe Compton losses may
explain the non-detections of optical flashes in several long GRBs. Such failed
optical flashes should be especially efficient GeV producers and likely to
develop e+- cascades. This probably happened in GRB 941017, and its mysterious
high-energy component is well explained by Compton upscattering of GRB photons
at the fireball deceleration radius. The proposed mechanism of GeV emission
should not work for short gamma-ray bursts that early decouple from the
fireball and avoid interaction with the electrons in the deceleration flash.
Observations by Swift and GLAST will provide an opportunity to test these
expectations. The existing data for GRB 990123 already impose interesting
constraints on the explosion.


title: Outflows and inflows in astrophysical systems

abstract:
  We seek for self-similar solutions describing the time-dependent evolution of
self-gravity systems with either spherical symmetry or axisymmetric disk
geometry. By assuming self-similar variable $x\equiv r/at$ where $a$ is
isothermal sound speed we find self-similar solutions extending from the
initial instant $t=0$ to the final stage $t\to \infty$ using standard
semi-analytical methods. Different types of solutions are constructed, which
describe overall expansion or collapse, envelope expansion with core collapse
(EECC), the formation of central rotationally supported quasi-equilibrium disk
as well as shocks. Though infinitely many, these self-similarity solutions have
similar asymptotic behaviors which may impose diagnosis on the velocity and
density structures in astrophysical systems.


title: A New Catalog of Radio Compact HII Regions in the Milky Way

abstract:
  We utilize new VLA Galactic plane catalogs at 5 and 1.4 GHz covering the
first Galactic quadrant (350<l<42, |b|<0.4) in conjunction with the MSX6C
Galactic plane catalog to construct a large sample of ultra-compact HII
regions. A radio catalog of this region was first published by Becker et al.
(1994), but we have added new observations and re-reduced the data with
significantly improved calibration and mosaicing procedures, resulting in a
tripling of the number of 5 GHz sources detected. Comparison of the new 5 GHz
catalog and the MSX6C Galactic plane catalog resulted in a sample of 687
matches, out of which we estimate only 15 to be chance coincidences. Most of
the matches show red MSX colors and a thermal radio spectrum. The scale height
of their Galactic latitude distribution is very small (FWHM of 16' or ~40 pc).
These properties suggest that the sample is dominated by young ultra-compact
HII regions, most of which are previously uncataloged. High reliability and low
reliability source lists are available for download with the paper.


title: Why there are no jets from cataclysmic variable stars

abstract:
  We argue that the recent thermal model of jet launching by young stellar
objects, when applied to system containing disk-accreting white dwarfs
naturally explain the otherwise astonishing absence of jets in cataclysmic
variable stars. Thermal launching is possible when the accreted material is
strongly shocked due to large gradients of physical quantities in the boundary
layer (or at the inner boundary of a truncated disk) and then cools on a time
scale longer than its ejection time from the disk. In our framework the
magnetic fields are weak, and serve only to recollimate the outflow at large
distances from the source, or to initiate the shock, but not as a jet-driving
agent. Using criteria for shock formation and mass ejection, we find the mass
accretion rate above which jets can be launched from boundary layers around
accreting white dwarfs to be ~10^{-6} Mo/y, which explains the absence of jets
in cataclysmic variable stars and their presence in other white-dwarf accreting
systems such as super-soft X-ray sources, symbiotic stars and classical novae.


title:
Candidate Type II Quasars from the SDSS: III. Spectropolarimetry Reveals
  Hidden Type I Nuclei

abstract:
  We have conducted spectropolarimetry of 12 type II (obscured) quasar
candidates selected from the spectroscopic database of the Sloan Digital Sky
Survey based on their emission line properties. Polarization was detected in
all objects, with nine being highly polarized (> 3%) and with polarization
reaching as high as 17% in two objects. Broad lines were detected in the
polarized spectra of five objects. These observations prove beyond a reasonable
doubt that the objects in our sample are indeed type II quasars, in that they
harbor luminous UV-excess AGNs in their centers and that the direct view to the
AGN is highly obscured. For three of the objects in this paper, we have
obtained HST images in three bands. The HST observations, combined with the
spectropolarimetry data, imply that scattering off material outside the
obscuration plane is the dominant polarization mechanism. In all three objects
the sizes of scattering regions are a few kpc. For one object, the extent of
the scattering region, coupled with the characteristics of the polarized
spectrum, argue strongly that dust scattering rather than electron scattering
dominates the polarized light. Our observations are well-described by the basic
orientation-based unification model of toroidal obscuration and off-plane
scattering, implying that the model can be extended to include at least some
high-luminosity AGNs.


title: Extra-planar HI in the starburst galaxy NGC 253

abstract:
  Observations of the nearby starburst galaxy NGC 253 in the 21-cm line reveal
the presence of neutral hydrogen in the halo, up to 12 kpc from the galactic
plane. This extra-planar HI is found only in one half of the galaxy and is
concentrated in a half-ring structure and plumes which are lagging in rotation
with respect to the disk. The HI plumes are seen bordering the bright Halpha
and X-ray halo emission. It is likely that, as proposed earlier for the Halpha
and the X-rays, also the origin of the extra-planar HI is related to the
central starburst and to the active star formation in the disk. A minor merger
and gas accretion are also discussed as possible explanations.
  The HI disk is less extended than the stellar disk. This may be the result of
ionization of its outer parts or, alternatively, of tidal or ram pressure
stripping.


title: Accelerated expansion in a stochastic self-similar fractal Universe

abstract:
  In a recent paper, a cosmological model based on El Naschie {\it E} infinity
cantorian spacetime was presented [Iovane, G.; Chaos, Solitons and Fractals,
20: 657-667, (2004)]. In that work it was claimed that the present accelerated
expansion of the Universe can be obtained as the effect of a scaling law on
newtonian cosmology with a certain time dependent gravitational constant ($G$).
In the present work we show that it may be problematic to explain the present
accelerated expansion of the Universe using the approach presented in
\cite{iovane}. As a better alternative we apply the same scaling law and a
time-dependent gravitational constant, that follows from the observational
constraints, to relativistic cosmology, i.e. the Friedmann's model. We are able
to show that for a matter-dominated flat Universe, with the scaling law and a
varying $G$, an accelerated expansion emerges in such a way that the function
luminosity distance vs redshift can be made close to the corresponding function
that comes from the usual Friedmann's model supplemented with a cosmological
constant of value $\Omega_{\Lambda}\simeq0.7$. Then the measurements of high
redshift supernovae, could be interpreted as a consequence of the fractal-self
similarity of the $G$ varying relativistic universe.


title:
A three-dimensional study of reconnection, current sheets and jets
  resulting from magnetic flux emergence in the Sun

abstract:
  We present the results of a set of three-dimensional numerical simulations of
magnetic flux emergence from below the photosphere into the corona that include
a uniform and horizontal coronal magnetic field mimicking a pre-existing
large-scale coronal magnetic system. Cases with different relative orientations
of the upcoming and coronal fields are studied. Upon contact, a concentrated
current sheet with the shape of an arch or bridge is formed at the interface
which marks the positions of maximum jump in the field vector between the two
systems. Relative angles above 90 degrees yield abundant magnetic reconnection
and plasma heating. The reconnection is seen to be intrisincally
three-dimensional in nature, except at singular positions along the current
sheet. It drives collimated high-speed and high-temperature outflows only a
short distance from the reconnection site that propagate along the ambient
magnetic field lines as jets. Due to the low plasma density in the corona,
these jets may propagate over large distances and, therefore help distribute
high-density and high-temperature plasma along these newly reconnected field
lines. The experiments permit to discern and visualize the three-dimensional
shape and relative position of the upcoming plasma hill, high-speed jets and
subphotospheric flux system. As a result of the reconnection, magnetic field
lines from the magnetized plasma below the surface end up as coronal field
lines, thus causing a profound change in the connectivity of the magnetic
regions in the corona. The experiments presented here thus yield a number of
features repeatedly observed with the TRACE satellite and the YOHKOH-SXT
detector, like the establishment of connectivity between emergent and
pre-existing active regions, local heating and high-velocity outflows.


title: Development of a Si/CdTe semiconductor Compton telescope

abstract:
  We are developing a Compton telescope based on high resolution Si and CdTe
imaging devices in order to obtain a high sensitivity astrophysical observation
in sub-MeV gamma-ray region. In this paper, recent results from the prototype
Si/CdTe semiconductor Compton telescope are reported. The Compton telescope
consists of a double-sided Si strip detector (DSSD) and CdTe pixel detectors,
combined with low noise analog LSI, VA32TA. With this detector, we obtained
Compton reconstructed images and spectra from line gamma-rays ranging from 81
keV up to 356 keV. The energy resolution is 3.8 keV and 7.9 keV at 122 keV and
356 keV, respectively, and the angular resolution is 9.9 degrees and 5.7
degrees at 122 keV and 356 keV, respectively.


title:
Ultra Deep Survey for Irregular Satellites of Uranus: Limits to
  Completeness

abstract:
  We present a deep optical survey of Uranus' Hill sphere for small satellites.
The Subaru 8-m telescope was used to survey about 3.5 square degrees with a 50%
detection efficiency at limiting red magnitude m = 26.1 mag. This magnitude
corresponds to objects that are about 7 km in radius (assuming an albedo of
0.04). We detected (without prior knowledge of their positions) all previously
known outer satellites and discovered two new irregular satellites (S/2001 U2
and S/2003 U3). The two inner satellites Titania and Oberon were also detected.
One of the newly discovered satellites (S/2003 U3) is the first known irregular
prograde of the planet. The population, size distribution and orbital
parameters of Uranus' irregular satellites are remarkably similar to the
irregular satellites of gas giant Jupiter. Both have shallow size distributions
(power law indices q~2 for radii > 7 km) with no correlation between the sizes
of the satellites and their orbital parameters. However, unlike those of
Jupiter, Uranus' irregular satellites do not appear to occupy tight distinct
dynamical groups in semi-major axis versus inclination phase space. Two
groupings in semi-major axis versus eccentricity phase space appear to be
statistically significant.


title: Optical afterglows of short Gamma-ray Bursts and GRB 040924

abstract:
  Short-duration Gamma-ray bursts (GRBs) (\leq 2{\rm s}) have remained a
mystery due to the lack of afterglow detection until recently. The models to
interpret short GRBs invoke distinct progenitor scenarios. Here we present a
generic analysis of short GRB afterglows, and calculate the optical lightcurves
of short GRBs within the framework of different progenitor models. We show that
all these optical afterglows are bright enough to be detected by the
Ultraviolet and Optical Telescope (UVOT) on board the {\em Swift} observatory,
and that different models could be distinguished with a well-monitored
lightcurve. We also model the afterglow data of the recently discovered short
burst GRB 040924. We find that the limited data are consistent with a low
medium density environment which is consistent with the pre-concept of the
compact-star merger progenitor model, although the models with a collapsar
progenitor are not ruled out.


title: Relic neutrino background from cosmological supernovae

abstract:
  Present and future observations of supernova relic neutrinos (SRNs), i.e., a
cosmological neutrino background from past core-collapse supernova explosions,
potentially give us useful information concerning various fields of
astrophysics, cosmology and particle physics. We review recent progress of
theoretical and observational studies of SRNs, particularly focusing on the
detectability and also on implications for cosmic star formation history and
neutrino physics.


title: Thermal condensation in a turbulent atomic hydrogen flow

abstract:
  We present a numerical and analytical study of the thermal fragmentation of a
turbulent flow of interstellar hydrogen. We first present the different
dynamical processes and the large range of spatial (and temporal) scales that
need to be adequately represented in numerical simulations. Next, we present
bidimensionnal simulations of turbulent converging flows which induce the
dynamical condensation of the warm neutral phase into the cold phase. We then
analyse the cold structures and the fraction of unstable gas in each
simulation, paying particular attention to the influence of the degree of
turbulence. When the flow is very turbulent a large fraction of the gas remains
in the thermally unstable domain. This unstable gas forms a filamentary
network. We show that the fraction of thermally unstable gas is strongly
correlated with the level of turbulence of the flow. We then develop a
semi-analytical model to explain the origin of this unstable gas. This simple
model is able to reproduce quantitatively the fraction of unstable gas observed
in the simulations and its correlation with turbulence. Finally, we stress the
fact that even when the flow is very turbulent and in spite of the fact that a
large fraction of the gas is maintained dynamically in the thermally unstable
domain, the classical picture of a 2-phase medium with stiff thermal fronts and
local pressure equilibrium turns out to be still relevant in the vicinity of
the cold structures.


title: Reconstruction of large-scale peculiar velocity fields

abstract:
  A reconstruction method for recovering the initial conditions of the Universe
starting from the present galaxy distribution is presented which guarantees
uniqueness of solutions. We show how our method can be used to obtain the
peculiar velocities of a large number of galaxies, hence trace galaxies orbits
back in time and obtain the entire past dynamical history of the Universe above
scales where multi-streaming has not occurred. When tested against a 128^3
LambdaCDM simulation in a box of 200 Mpc/h length, we obtain 60% exact
reconstruction on scales above 6 Mpc/h. We apply our method to a real galaxy
redshift catalogue, the updated NBG (Nearby Galaxies), containing 1483
galaxies, groups and clusters in a radius of 30 Mpc/h, and reconstruct the
peculiar velocity fields in the local neighbourhood. Our reconstructed
distances are well-matched to the observed values outside the collapsed regions
if Omega_m(t)= 0.20 exp(-0.26 (t-13)) where t is the age of the Universe in
Gyrs.


title: On the Observability of Giant Protoplanets in Circumstellar Disks

abstract:
  We investigate the possibility to detect giant planets that are still
embedded in young circumstellar disks. Based on models with different stellar,
planetary, and disk masses, and different radial positions of the planet we
analyze the resulting submillimeter appearance of these systems. We find that
the influence of the planet on the spectral energy distribution could not be
distinguished from that of other disk parameters. However, dust reemission
images of the disks show that the hot region in the proximity of a young
planet, along with the gap, could indeed be detected and mapped with the
Atacama Large Millimeter Array in the case of nearby circumstellar disks
(d<100pc) in approximate face-on orientation.


title: The Local Group and other neighboring galaxy groups

abstract:
  Over the last few years, rapid progress has been made in distance
measurements for nearby galaxies based on the magnitude of the tip of red giant
branch stars. Current CCD surveys with HST and large ground- based telescopes
bring $\sim$10%-accurate distances for roughly a hundred galaxies within 5 Mpc.
The new data on distances to galaxies situated in (and around) the nearest
groups: the Local Group, M81 group, CenA/M83 group, IC342/Maffei group,
Sculptor filament, and Canes Venatici cloud allowed us to determine their total
mass from the radius of the zero- velocity surface, $R_0$, which separates a
group as bound against the homogeneous cosmic expansion. The values of $R_0$
for the virialized groups turn out to be close each other, in the range of 0.9
-- 1.3 Mpc. As a result, the total masses of the groups are close to each
other, too, yielding total mass-to-blue luminosity ratios of 10 -- 40
$M_{\sun}/L_{\sun}$. The new total mass estimates are 3 -- 5 times lower than
old virial mass estimates of these groups. Because about half of galaxies in
the Local Volume belong to such loose groups, the revision of the amount of
dark matter (DM) leads to a low local density of matter, $\Omega_m \simeq
0.04$, which is comparable with the global baryonic fraction $\Omega_b$, but
much lower than the global density of matter, $\Omega_m = 0.27$.
  To remove the discrepancy between the global and local quantities of
$\Omega_m$, we assume the existence of two different DM components: 1) compact
dark halos around individual galaxies and 2) a non-baryonic dark matter
``ocean'' with $\Omega_{dm1} \simeq 0.07$ and $\Omega_{dm2} \simeq 0.20$,
respectively.


title:
The Star Formation Region NGC 6530: distance, ages and Initial Mass
  Function

abstract:
  We present astrometry and $BVI$ photometry, down to $V\simeq22$, of the very
young open cluster NGC6530, obtained from observations taken with the Wide
Field Imager camera at the MPG/ESO 2.2 m Telescope. Both the $V$ vs. $B-V$ and
the $V$ vs. $V-I$ color-magnitude diagrams (CMD) show the upper main sequence
dominated by very bright cluster stars, while, due to the high obscuration of
the giant molecular cloud surrounding the cluster, the blue envelopes of the
diagrams at $V\gtrsim 14$ are limited to the main sequence stars at the
distance of NGC6530. This particular structure of the NGC6530 CMD allows us to
conclude that its distance is about $d \simeq 1250$ pc, significantly lower
than the previous determination of d=1800 pc. We have positionally matched our
optical catalog with the list of X-ray sources found in a Chandra-ACIS
observation, finding a total of 828 common stars, 90% of which are pre-main
sequence stars in NGC6530. Using evolutionary tracks of Siess et al. (2000)},
mass and age values are inferred for these stars. The median age of the cluster
is about 2.3 Myr; in the mass range (0.6--4.0)$ M_\odot$, the Initial Mass
Function (IMF) shows a power law index $x=1.22\pm0.17$, consistent with both
the Salpeter index (1.35), and with the index derived for other young clusters
; towards smaller masses the IMF shows a peak and then it starts to decrease.


title:
Interpretation of the Spectra Originating from the Photospheres
  Contaminated with Dust - Experience in L and T Dwarfs

abstract:
  Recent observations revealed that the infrared colors of L and T dwarfs show
a large variation at a given T_ eff and this result may imply that the
thickness of the dust cloud is changing at a given T_ eff. Our Unified Cloudy
Model (UCM), in which the dust cloud forms between the condensation
temperature, T_cond, and the critical temperature, T_cr, is already prepared
for such a new situation and can be used by simply changing T_cr at a given
T_eff, instead of assuming a constant value of T_cr=1800K throughout as in our
previous applications of the UCMs. However, the effects of T_eff and T_cr on
individual spectra are difficult to discriminate, since the effect of T_eff at
a fixed T_cr on one hand and the effect of T_cr at a fixed T_eff on the other
have essentially the same effect on the spectra. For this reason, spectra of
dusty dwarfs were in fact misinterpreted in general, also by ourselves. We show
that the degeneracy of T_eff and T_cr can be removed to some extent by the
analysis of the spectra transformed to the SEDs on an absolute scale. Our
reanalysis of some spectra revealed that the L-T spectral sequence is not a
sequence of T_eff, at least between middle L and early T types, but should be
interpreted as a sequence of T_cr. In other words, the L-T spectral sequence
has little to do with T_eff but reflects a change of the thickness of the dust
cloud. Although this unexpected result is based on a limited sample, an odd
``brightening'' of the absolute magnitudes (e.g., M_J and M_bol) plotted
against the L-T spectral types may also be a manifestation that the L-T
spectral sequence is not a temperature sequence. :


title: SNII enrichment and the star cluster mass function

abstract:
  Changing the form of the star cluster mass function (CMF) can effectively
change the upper end of the stellar initial mass function. The yields of from
supernovae are very sensitive to the mass of the progenitor star. We show that
by changing the parameters of the CMF, it is possible to change the yields of
oxygen and magnesium by a factor of $\sim 1.5$ and of metals in general by a
factor of $\sim 1.8$.


title: Spatial energy spectrum of primordial magnetic fields

abstract:
  Here, we analyze the primordial magnetic field transition between a radiative
and a matter-dominated universe. The gravitational structure formation affects
its evolution and energy spectrum. The structure excitation can trigger
magnetic field amplification and the steepening of its energy density spectrum.


title: Scaling behavior in warm inflation

abstract:
  We anlayze the dynamics of warm inflation models with general viscous
effects. We characterize the situations yielding asymptotic scaling behavior.


title: A disk in the Galactic Center in the past ?

abstract:
  We raise the question whether in the past a disk could have existed in our
Galactic Center which has disappeared now. Our model for the interaction of a
cool disk and a hot corona above (Liu et al. 2004) allows to estimate an upper
limit for the mass that might have been present in a putative accretion disk
after a last star forming event, but would now have evaporated by coronal
action.


title: Metals in the Neutral Interstellar Medium of Dwarf Star-Forming Galaxies

abstract:
  The determination of the metal abundances in the neutral interstellar medium
of dwarf star-forming galaxies is a key step in understanding their physical
and chemical evolution. This type of investigation has been possible in the
last 5 years thanks to FUSE. We will give a flavor of the issues involved by
presenting the work that we are performing in this astrophysical field.


title: Cosmic strings reborn?

abstract:
  There are two main reasons for the recent renewal of interest in cosmic
strings: Fundamental string-theory models suggest their existence; and there
are at least two tentative observations of their possible effects. In this
talk, I review their current status in the light of these two factors.


title: Optical properties of SMC X-ray binaries

abstract:
  This work represent the first major study of the optical and IR
characteristics of the mass donor companions to the X-ray pulsars in the Small
Magellanic Cloud (SMC). In this work several new counterparts have been
identified, and possible ones confirmed, as companions to X-ray pulsars in the
SMC giving a total of 34 such objects now identified. In addition this work
presents three new binary periods and confirms two X-ray periods using optical
data for objects in this group. This homogeneous sample has been studied as a
group to determine important general characteristics that may offer insight
into the evolution of such systems. In particular, the spectral class
distribution shows a much greater agreement with those of isolated Be stars,
and appears to be in some disagreement with the galactic population of Be stars
in Be/X-ray binaries. Studies of the long term optical modulation of the Be
star companions reveal an extremely variable group of objects, a fact which
will almost certainly make a major contribution to the pronounced X-ray
variability. The spatial distribution of these systems within the SMC is
investigated and strongly suggests a link between massive star formation and
the HI density distribution. Finally, studies of the circumstellar disk
characteristics reveal a strong link with optical variability offering
important clues into the long-term stability of such disks.


title: A High Temperature Liquid Plasma Model of the Sun

abstract:
  In this work, a liquid model of the Sun is presented wherein the entire solar
mass is viewed as a high density/high energy plasma. This model challenges our
current understanding of the densities associated with the internal layers of
the Sun, advocating a relatively constant density, almost independent of radial
position. The incompressible nature of liquids is advanced to prevent solar
collapse from gravitational forces. The liquid plasma model of the Sun is a
non-equilibrium approach, where nuclear reactions are free to occur throughout
the solar mass. The primary means of addressing internal heat transfer are
convection and conduction. As a result of the convective processes on the solar
surface, the liquid model brings into question the established temperature of
the solar photosphere by highlighting a violation of Kirchhoff's law of thermal
emission. Along these lines, the model emphasizes that radiative emission is a
surface phenomenon. Strong evidence is provided that the Sun is a high
density/high energy liquid plasma. This evidence is based on our knowledge of
Planckian thermal emission and condensed matter, including the existence of
pressure ionization and liquid metallic hydrogen at high temperatures and
pressures. The equations of magnetohydrodynamics are invoked as the proper
vehicle for the understanding od stellar convection and structure. Prior to
introducing the liquid plasma model, the historic and scientific justifications
for the gaseous model of the Sun are reviewed and the gaseous equations of
state are also discussed.


title: Planck-scale Lorentz-symmetry test theories

abstract:
  In the recent quantum-gravity literature there has been strong interest in
the possibility of Planck-scale departures from Lorentz symmetry, including
possible modifications of the energy/momentum dispersion relation. I stress
that a meaningful characterization of the progress of experimental bounds on
these Planck-scale effects requires the analysis of some reference test
theories, and I propose to focus on two ``minimal'' test theories, a
pure-kinematics test theory and an effective-field-theory-based test theory. I
illustrate some features of the phenomenology based on these test theories
considering some popular strategies for constraining Planck-scale effects, and
in particular I observe that sensitivities that are already in the Planck-scale
range for some parameters of the two test theories can be achieved using
observations of TeV photons from Blazars, both using the so-called ``gamma-ray
time-of-flight analyses'' and using the now robust evidence of absorption of
TeV photons. Instead the Crab-nebula synchrotron-radiation analyses, whose
preliminary sensitivity estimates raised high hopes, actually do not lead to
any bound on the parameters of the two ``minimal'' test theories. The
Crab-nebula synchrotron-radiation analyses do however constrain some possible
generalizations of one of the minimal test theories. As an example of
forthcoming data which could provide extremely stringent (beyond-Planckian)
limits on the two minimal test theories I consider the possibility of studies
of the GZK cutoff for cosmic-rays.


title: Thick CZT Detectors for Space-Borne X-ray Astronomy

abstract:
  Cadmium Zinc Telluride (CZT) detectors are having a major impact on the field
of hard X-ray astronomy. Without the need for cryogenic cooling they achieve
good spatial and energy resolutions over the broad energy range from 10 keV to
600 keV. In this paper, we briefly review the historical development of
detectors used in X-ray astronomy. Subsequently, we present an evaluation of
CZT detectors from the company Imarad. The standard 2x2x0.5 cm detectors,
contacted with 8x8 In pixels and an In cathode, exhibit FWHM energy resolutions
of 7 keV at 59 keV, and 10 keV at 662 keV. A direct measurement of the 662 keV
photopeak efficiency gives 67%. We have started a detailed study of the
performance of Imarad detectors depending on surface preparation, contact
materials, contact deposition, post-deposition detector annealing, and detector
passivation techniques. We present first results from contacting detectors with
Cr, Ag, Au, and Pt.


title: Catalog of Nearby Galaxies and the Local Cosmic Web

abstract:
  We compiled an all-sky catalog of 451 nearby galaxies, each having an
individual distance estimate $D \la 10$ Mpc or the radial velocity $V_{LG} <
550$ km s$^{-1}$. The catalog contains data on basic optical and HI properties
of the galaxies: their diameters, absolute magnitudes, morphological types,
optical and HI surface brightnesses, rotational velocities, indicative
mass-to-luminosity and HI mass-to-luminosity ratios, as well as a so-called
"tidal index", which quantifies the galaxy environment. We expect the catalog
completeness to be $\sim75$% within 8 Mpc. About 85% of the Local volume
population are dwarf (dIrr, dIm, dSph) galaxies with $M_B>-17.0$, which
contribute about 4% to the local luminosity density, and $\sim(10-16)$% to the
local HI mass density.
  We found that the mean local barion density $\Omega_b(<8$ Mpc) = 2.3%
consists of only a half of the global barion density, $\Omega_b=(4.7\pm0.6)$%
(Spergel et al. 2003). The mean-square pairwise difference of radial velocities
is about 100 km s$^{-1}$ for spatial separations within 1 Mpc, increasing to
$\sim 300$ km s$^{-1}$ on a scale of $\sim 3$ Mpc.


title: X-ray Variability of AGN and the Flare Model

abstract:
  Short-term variability of X-ray continuum spectra has been reported for
several Active Galactic Nuclei. Significant X-ray flux variations are observed
within time scales down to 10^3-10^5 seconds. We discuss short variability time
scales in the frame of the X-ray flare model, which assumes the release of a
large hard X-ray flux above a small portion of the accretion disk. The
resulting observed X-ray spectrum is composed of the primary radiation and of a
reprocessed Compton reflection component that we model with numerical radiative
transfer simulations. The incident hard X-rays of the flare will heat up the
atmosphere of the accretion disk and hence induce thermal expansion.
Eventually, the flare source will be surrounded by an optically thick medium,
which should modify the observed spectra.


title: Feedback and the Initial Mass function

abstract:
  I describe a turbulence-inspired model for the stellar initial mass function
which includes feedback and self-regulation via protostellar outflows. A new
aspect of the model provides predictions of the star formation rate in
molecular clouds and gas complexes. A similar approach is discussed for
self-regulation on kiloparsec scales via supernova input, and an expression is
presented for the global star formation rate that depends on the turbulent
pressure of the interstellar medium.


title: Kepler's Supernova Remnant: The view at 400 Years

abstract:
  October 2004 marks the 400th anniversary of the sighting of SN 1604, now
marked by the presence of an expanding nebulosity known as Kepler's supernova
remnant. Of the small number of remnants of historical supernovae, Kepler's
remnant remains the most enigmatic. The supernova type, and hence the type of
star that exploded, is still a matter of debate, and even the distance to the
remnant is uncertain by more than a factor of two. As new and improved
multiwavength observations become available, and as the time baseline of
observations gets longer, Kepler's supernova remnant is slowly revealing its
secrets. I review recent and current observations of Kepler's supernova remnant
and what they indicate about this intriguing object.


title: FUSE Observations of Variability in Hot-Star Winds

abstract:
  New constraints on the large-scale wind structures responsible for discrete
absorption components are obtained from far-ultraviolet time-series
observations of O supergiants in the Large Magellanic Cloud.


title: Multi-wavelength study of a sample of nearby Seyfert galaxies

abstract:
  One of the least biased complete Seyfert sample available to date has been
considered to perform an X-ray survey using the capabilities of XMM-Newton and
Chandra satellites. The X-ray nuclear luminosities obtained have been used to
perform a multi-wavelength analysis as a powerfull tool in the identification
of heavily obscured objects. The new X-ray data, together with highest quality
nuclear fluxes available from the radio to the optical band, allow us to obtain
nuclear Spectral Energy Distributions (SEDs) for type 1 and type 2 objects in
our sample. The results obtained from the analysis of the SED have been
discussed in the framework of Unified Models.


title: Comparing spectroscopic and photometric stellar mass estimates

abstract:
  The purpose of this letter is to compare the quality of different methods for
estimating stellar masses of galaxies. We compare the results of (a) fitting
stellar population synthesis models to broad band colors from SDSS and 2MASS,
(b) the analysis of spectroscopic features of SDSS galaxies (Kauffmann et al.
2003), and, (c) a simple dynamical mass estimate based on SDSS velocity
dispersions and effective radii. Knowing that all three methods can have
significant biases, a comparison can help to establish their (relative)
reliability. In this way, one can also probe the quality of the observationally
cheap broadband color mass estimators for galaxies at higher redshift.
Generally, masses based on broad-band colors and spectroscopic features agree
reasonably well, with a rms scatter of only ~ 0.25 dex over almost 4 decades in
mass. However, as may be expected, systematic differences do exist and have an
amplitude of ~ 0.15 dex, corrleting with Halpha emission strength.
Interestingly, masses from broad-band color fitting are in better agreement
with dynamical masses than masses based on the analysis of spectroscopic
features. In addition, the differences between the latter and the dynamical
masses correlate with Halpha equivalent width, while this much less the case
for the broad-band masses. We conclude that broad band color mass estimators,
provided they are based on a large enough wavelength coverage and use an
appropriate range of ages, metallicities and dust extinctions, can yield fairly
reliable stellar masses for galaxies. This is a very encouraging result as such
mass estimates are very likely the only ones available at significant redshifts
for some time to come.


title:
The Core Collapse Supernova Mechanism: Current Models, Gaps, and the
  Road Ahead

abstract:
  The pursuit of the core collapse supernova explosion mechanism continues.
While such efforts have been undertaken over the last four decades, it is only
in the last decade that multidimensional models have been developed, and only
in the last few years that significant components of supernova models, such as
the neutrino transport, have been modeled with sufficient realism. We can now
identify what are arguably the important components that must be included in
any realistic three-dimensional supernova model. The challenge we now face is
to include all of these in the models.


title:
A Signature of Planetary Migration: The Origin of Asymmetric Capture in
  the 2:1 Resonance

abstract:
  The spatial distribution of Kuiper belt objects (KBOs) in 2:1 exterior
resonance with Neptune constrains that planet's migration history. Numerical
simulations demonstrate that fast planetary migration generates a larger
population of KBOs trailing rather than leading Neptune in orbital longitude.
This asymmetry corresponds to a greater proportion of objects caught into
asymmetric resonance such that their resonance angles librate about values > pi
(trailing) as opposed to < pi (leading). We provide, for the first time, an
explanation of this phenomenon, using physical, analytic, and semi-analytic
arguments. Central to our understanding is how planetary migration shifts the
equilibrium points of the superposed direct and indirect potentials. Large
capture asymmetries appear for exponential timescales of migration shorter than
10 Myr. The observed distribution of 2:1 KBOs (2 trailing and 7 leading)
excludes migration timescales < 1 Myr with 99.65% confidence.


title: Exploring the Universe beyond the Photon Window

abstract:
  In this talk I review how to identify cosmic ray accelerators that are high
energy neutrino emitters. I also delineate the prospects for a new
multi-particle astronomy: neutrons as directional pointers + antineutrinos as
inheritors of directionality.


title: Toward an Improved Analytical Description of Lagrangian Bias

abstract:
  We carry out a detailed numerical investigation of the spatial correlation
function of the initial positions of cosmological dark matter halos. In this
Lagrangian coordinate system, which is especially useful for analytic studies
of cosmological feedback, we are able to construct cross-correlation functions
of objects with varying masses and formation redshifts and compare them with a
variety of analytical approaches. For the case in which both formation
redshifts are equal, we find good agreement between our numerical results and
the bivariate model of Scannapieco & Barkana (2002; SB02) at all masses,
redshifts, and separations, while the model of Porciani et al. (1998) does well
for all parameters except for objects with different masses at small
separations. We find that the standard mapping between Lagrangian and Eulerian
bias performs well for rare objects at all separations, but fails if the
objects are highly-nonlinear (low-sigma) peaks. In the Lagrangian case in which
the formation redshifts differ, the SB02 model does well for all separations
and combinations of masses, apart from a discrepancy at small separations in
situations in which the smaller object is formed earlier and the difference
between redshifts or masses is large. As this same limitation arises in the
standard approach to the single-point progenitor distribution developed by
Lacey & Cole (1993), we conclude that a more complete understanding of the
progenitor distribution is the most important outstanding issue in the analytic
modeling of Lagrangian bias.


title: P V and the Mass Loss Discrepancy in O Stars

abstract:
  Building upon a previous analysis of P V wind lines in LMC O stars, we
analyze the P V wind lines in a sample of Galactic O stars which have empirical
mass loss rates determined from either their radio fluxes or H alpha profiles.
Since the wind analysis provides a measure of \dot{M}q where q is the
ionization fraction of the ion, we determine q(P V) observationally. In spite
of model predictions that q should be about 1 for mid-O stars, we find q(P V)
is less than 0.15 throughout the O stars. We discuss the origin of this
discrepancy.


title: Modelling the X-ray spectra of high velocity outflows from quasars

abstract:
  High velocity outflows from supermassive black holes have been invoked to
explain the recent identification of strong absorption features in the hard
X-ray spectra of several quasars. Here, Monte Carlo radiative transfer
calculations are performed to synthesise X-ray spectra from models of such
flows. It is found that simple, parametric bi-conical outflow models with
plausible choices for the wind parameters predict spectra that are in good
qualitative agreement with observations in the 2 - 10 keV band. The influence
on the spectrum of both the mass-loss rate and opening angle of the flow are
considered: the latter is important since photon leakage plays a significant
role in establishing an ionization gradient within the flow, a useful
discriminant between spherical and conical outflow for this and other
applications. Particular attention is given to the bright quasar PG1211+143 for
which constraints on the outflow geometry and mass-loss rate are discussed
subject to the limitations of the currently available observational data.


title:
The interstellar C18O/C17O ratio in the solar neighbourhood: The rho Oph
  cloud

abstract:
  Observations of up to ten carbon monoxide (CO and isotopomers) transitions
are presented to study the interstellar C18O/C17O ratio towards 21 positions in
the nearby (d~140pc) low-mass star forming cloud rho Oph. A map of the C18O
J=1-0 distribution of parts of the cloud is also shown. An average
12C18O/12C17O isotopomeric ratio of 4.11 +/- 0.14, reflecting the 18O/17O
isotope ratio, is derived from Large Velocity Gradient (LVG) calculations. From
LTE column densities we derive a ratio of 4.17 +/-0.26. These calculations also
show that the kinetic temperature decreases from about 30 K in the cloud
envelope to about 10 K in the cloud cores. This decrease is accompanied by an
increase of the average molecular hydrogen density from 10^4 cm-3 to >10^5
cm-3. Towards some lines of sight C18O optical depths reach values of order
unity.


title: Deconvolution Map-Making for Cosmic Microwave Background Observations

abstract:
  We describe a new map-making code for cosmic microwave background (CMB)
observations. It implements fast algorithms for convolution and transpose
convolution of two functions on the sphere (Wandelt & G\'{o}rski 2001). Our
code can account for arbitrary beam asymmetries and can be applied to any
scanning strategy. We demonstrate the method using simulated time-ordered data
for three beam models and two scanning patterns, including a coarsened version
of the WMAP strategy. We quantitatively compare our results with a standard
map-making method and demonstrate that the true sky is recovered with high
accuracy using deconvolution map-making.


title: NLTE Model Atmosphere Analysis of the LMC Supersoft X-ray Source CAL 83

abstract:
  We present a non-LTE model atmosphere analysis of Chandra HRC-S/LETG and
XMM-Newton RGS spectroscopy of the prototypical supersoft source CAL 83 in the
Large Magellanic Cloud. Taken with a 16-month interval, the Chandra and
XMM-Newton spectra are very similar. They reveal a very rich absorption line
spectrum from the hot white dwarf photosphere, but no spectral signatures of a
wind. We also report a third X-ray off-state during a later Chandra
observation, demonstrating the recurrent nature of CAL 83. Moreover, we found
evidence of short-timescale variability in the soft X-ray spectrum. We
completed the analysis of the LETG and RGS spectra of CAL 83 with new NLTE
line-blanketed model atmospheres that explicitly include 74 ions of the 11 most
abundant species. We successfully matched the Chandra and XMM-Newton spectra
assuming a model composition with LMC metallicity. We derived the basic stellar
parameters of the hot white dwarf, but the current state of atomic data in the
soft X-ray domain precludes a detailed chemical analysis. We have obtained the
first direct spectroscopic evidence that the white dwarf is massive (Mwd > 1
Msun). The short timescale of the X-ray off-states is consistent with a high
white dwarf mass. Our analysis thus provides direct support for supersoft
sources as likely progenitors of SN Ia.


title: From z>6 to z~2: Unearthing Galaxies at the Edge of the Dark Ages

abstract:
  Galaxies undergoing formation and evolution can now be observed over a time
baseline of some 12 Gyr. An inherent difficulty with high-redshift observations
is that the objects are very faint and the best resolution (HST) is only ~0.5
kpc. Such studies thereby combine in a highly synergistic way with the great
detail that can be obtained for nearby galaxies. 3 new developments are
highlighted. First is the derivation of stellar masses for galaxies from SEDs
using HST and now Spitzer data, and dynamical masses from both sub-mm
observations of CO lines and near-IR observations of optical lines like Halpha.
A major step has been taken with evidence that points to the z~2-3 LBGs having
masses that are a few x 10^10 Msolar. Second is the discovery of a population
of evolved red galaxies at z~2-3 which appear to be the progenitors of the more
massive early-type galaxies of today, with dynamical masses around a few x
10^11 Msolar. Third are the remarkable advances that have occurred in
characterizing dropout galaxies to z~6 and beyond, < 1 Gyr from recombination.
The HST ACS has played a key role here, with the dropout technique being
applied to i & z images in several deep ACS fields, yielding large samples of
these objects. This has allowed a detailed determination of their properties
and meaningful comparisons against lower-z samples. The use of cloning
techniques has overcome many of the strong selection biases affecting the study
of these objects. A clear trend of size with redshift has been identified, and
its impact on the luminosity density and SFR estimated. There is a significant
though modest decrease in the SFR from z~2.5 to z~6. The latest data also allow
for the first robust determination of the LF at z~6. Finally, the latest UDF
ACS and NICMOS data has resulted in the detection of some galaxies at z~7-8.


title:
Attenuation of Millimeter Emission from Circumstellar Disks Induced by
  the Rapid Dust Accretion

abstract:
  From millimeter observations of classical T Tauri stars, it is suggested that
dust grains in circumstellar disks have grown to millimeter size or larger.
However, gas drag on such large grains induces rapid accretion of the dust. We
examine the evolution of dust disks composed of millimeter sized grains, and
show that rapid accretion of the dust disk causes attenuation of millimeter
continuum emission. If a dust disk is composed mainly of grains of 1 cm to 1 m,
its millimeter emission goes off within 10^6 yr. Hence, grains in this size
range cannot be a main population of the dust. Considering our results together
with grain growth suggested by the millimeter continuum observations, we expect
that the millimeter continuum emission of disks comes mainly from grains in a
narrow size range of [1 mm -1 cm]. This suggests either that growth of
millimeter sized grains to centimeter size takes more than 10^6 yr, or that
millimeter sized grains are continuously replenished. In the former case,
planet formation is probably difficult, especially in the outer disks. In the
latter case, reservoirs of millimeter grains are possibly large (> 10 m)
bodies, which can reside in the disk more than 10^6 yr. Constraints on the
grain growth time-scale are discussed for the above two cases.


title: The neutral gas in the environs of the Geminga gamma-ray pulsar

abstract:
  We present a high-resolution (24 arcsec) study of the HI interstellar gas
distribution around the radio-quiet neutron star Geminga. Based on Very Large
Array (VLA) and MPIfR Effelsberg telescope data, we analyzed a 40' x 40' field
around Geminga. These observations have revealed the presence of a neutral gas
shell, 0.4 pc in radius, with an associated HI mass of 0.8 Msun, which
surrounds Geminga at a radial velocity compatible with the kinematical distance
of the neutron star. In addition, morphological agreement is observed between
the internal face of the HI shell and the brightest structure of Geminga's tail
observed in X-rays.We explore the possibility that this morphological agreement
is the result of a physical association.


title:
Error analysis of quadratic power spectrum estimates for CMB
  polarization: sampling covariance

abstract:
  Quadratic methods with heuristic weighting (e.g. pseudo-C_l or correlation
function methods) represent an efficient way to estimate power spectra of the
cosmic microwave background (CMB) anisotropies and their polarization. We
construct the sample covariance properties of such estimators for CMB
polarization, and develop semi-analytic techniques to approximate the
pseudo-C_l sample covariance matrices at high Legendre multipoles, taking
account of the geometric effects of mode coupling and the mixing between the
electric (E) and magnetic (B) polarization that arise for observations covering
only part of the sky. The E-B mixing ultimately limits the applicability of
heuristically-weighted quadratic methods to searches for the gravitational-wave
signal in the large-angle B-mode polarization, even for methods that can
recover (exactly) unbiased estimates of the B-mode power. We show that for
surveys covering one or two per cent of the sky, the contribution of E-mode
power to the covariance of the recovered B-mode power spectrum typically limits
the tensor-to-scalar ratio that can be probed with such methods to around 0.05.


title:
Evidence for an inner molecular disk around massive Young Stellar
  Objects

abstract:
  We present observations of CO overtone bandhead emission toward four massive
Young Stellar Objects (spectral type O6--B5). The high signal-to-noise ratio
K-band spectra were obtained with VLT-ISAAC at a resolution of 30 km/s,
sufficient to resolve the bandheads, but not the individual J-lines. We are
able to explain the shape of the lines by assuming a simple isothermal
keplerian disk model seen at different inclinations. The gas temperature ranges
from 1500 to 4500 K and the CO column density is between 0.1 and 4 10^21 cm^-2.
The emission probably arises within the first few astronomical units of the
disk, consistent with the high gas temperature. Our results indicate that
molecules can survive close to a hot star and suggest that dense (n_H > 10^10
cm^-3) inner disks may be relatively common at an advanced stage of high-mass
star formation.


title:
X-ray spectral and timing characteristics of the stars in the young open
  cluster IC 2391

abstract:
  We present X-ray spectral and timing analysis of members of the young open
cluster IC 2391 observed with the XMM-Newton observatory. We detected 99 X-ray
sources by analysing the summed data obtained from MOS1, MOS2 and pn detectors
of the EPIC camera; 24 of them are members, or probable members, of the
cluster. Stars of all spectral types have been detected, from the early-types
to the late-M dwarfs.
  Despite the capability of the instrument to recognize up to 3 thermal
components, the X-ray spectra of the G, K and M members of the cluster are well
described with two thermal components (at kT$_1 \sim$ 0.3-0.5 keV and kT$_2
\sim$ 1.0-1.2 keV respectively) while the X-ray spectra of F members require
only a softer 1-T model.
  The Kolmogorov-Smirnov test applied to the X-ray photon time series shows
that approximately 46% of the members of IC 2391 are variable with a confidence
level $>$99%. The comparison of our data with those obtained with ROSAT/PSPC,
nine years earlier, and ROSAT/HRI, seven years earlier, shows that there is no
evidence of significant variability on these time scales, suggesting that
long-term variations due to activity cycles similar to that on the Sun are not
common, if present at all, among these young stars.


title: Correlation of IR and Opticical Variability in NGC4151

abstract:
  We combine all published NIR and optical photometrical observations of NGC
4151 as well as our new unpublished yet data which can be used for
determination of time delays between optical and NIR variations. Before we have
found change of time delay value for variations in K and L filters for
different states of the luminosity. Here we are considering new data for deep
minimum after the very high state of the nucleus. We conclude that dust
recovering time after the high state is for any case more then several years.


title:
Rotation and variability of very low mass stars and brown dwarfs near
  Epsilon Ori

abstract:
  We explore the rotation and activity of very low mass (VLM) objects by means
of a photometric variability study. Our targets in the vicinity of Epsilon Ori
belong to the OriOB1b population in the Orion star-forming complex. In this
region we selected 143 VLM stars and brown dwarfs (BDs), whose photometry in
RIJHK is consistent with membership of the young population. The variability of
these objects was investigated using a densely sampled I-band time series
covering four consecutive nights with altogether 129 data points per object.
Our targets show three types of variability: Thirty objects, including nine
BDs, show significant photometric periods, ranging from 4h up to 100h, which we
interpret as the rotation periods. Five objects, including two BDs, exhibit
variability with high amplitudes up to 1 mag which is at least partly
irregular. This behaviour is most likely caused by ongoing accretion and
confirms that VLM objects undergo a T Tauri phase similar to solar-mass stars.
Finally, one VLM star shows a strong flare event of 0.3 mag amplitude. The
rotation periods show dependence on mass, i.e. the average period decreases
with decreasing object mass, consistent with previously found mass-period
relationships in younger and older clusters. The period distribution of BDs
extends down to the breakup period, where centrifugal and gravitational forces
are balanced. Combining our BD periods with literature data, we found that the
lower period limit for substellar objects lies between 2h and 4h, more or less
independent of age. Contrary to stars, these fast rotating BDs seem to evolve
at constant rotation period from ages of 3 Myr to 1 Gyr, in spite of the
contraction process. Thus, they should experience strong rotational braking.


title:
The Turn-off of Classical Novae Observed Through X-rays: Models versus
  ROSAT Observations of V1974 Cyg

abstract:
  Detection of X-ray emission from classical novae in their post-outburst
stages provides crucial information about the nova phenomenon. The soft X-ray
emission gives a direct insight into the remaining hot nuclear burning shell. A
numerical model for steady H-burning white dwarf envelopes has been developed
to study the post-outburst phases of classical novae. Properties of the X-ray
emission of the post-nova white dwarf are obtained, and the results are
compared to ROSAT observations of V1974 Cyg.


title: Chameleon Dark Energy

abstract:
  Chameleons are scalar fields whose mass depends on the environment,
specifically on the ambient matter density. While nearly massless in the
cosmos, where the matter density is tiny, their mass is of order of an inverse
millimeter on Earth, where the density is high. In this note, we review how
chameleons can satisfy current experimental constraints on deviations from
General Relativity (GR). Moreover, we study the cosmological evolution with a
chameleon field and show the existence of an attractor solution, akin to the
tracker solution in quintessence models. We discuss how chameleons can
naturally drive the observed acceleration of the universe


title: Signatures of restarted activity in core-dominated triples

abstract:
  The lobes of radio-loud AGNs are huge reservoirs of energy so even if the
central engine turns off, the radio source is still observable for a
substantial amount of time. It is quite obvious, however, that the ignition of
a new period of activity can occur before the lobes have faded completely.
Restarted activity has been observed in several giant radio galaxies but until
recently, it has hardly ever been observed in more compact sources. Here we
present an early result of a pilot VLBA programme targeted at compact
core-dominated triples. It is found that the milliarcsecond structure of the
central components in that type of objects normally take the form of core-jets,
which in many cases do not point toward the relic lobes. Therefore, it looks as
if the phenomenon of the restarted activity can occur regardless of the source
size and it is often accompanied by a repositioning of the central engine.


title: XMM-Newton Observations of Recent Galactic Novae

abstract:
  We report on the observations of five recent galactic classical novae,
performed with XMM-Newton. Some of them show emission in the whole range from
0.2 to 8.0 keV, up to 3 years after the explosion. Nova Oph 1998 shows clear
evidence of resumed accretion less than 3 years after its explosion, indicating
a very fast recovery of the cataclysmic variable after the nova outburst. In
another case, Nova Sgr 1998, it is difficult to disentangle if the emission is
produced in the ejecta and/or in the accretion stream.


title:
The Primordial Binary Population - I: A near-infrared adaptive optics
  search for close visual companions to A star members of Scorpius OB2

abstract:
  We present the results of a near-infrared adaptive optics survey with the aim
to detect close companions to Hipparcos members in the three subgroups of the
nearby OB association Sco OB2: Upper Scorpius (US), Upper Centaurus Lupus (UCL)
and Lower Centaurus Crux (LCC). We have targeted 199 A-type and late B-type
stars in the Ks band, and a subset also in the J and H band. We find 151
stellar components other than the target stars. A brightness criterion is used
to separate these components into 77 background stars and 74 candidate physical
companion stars. Out of these 74 candidate companions, 41 have not been
reported before (14 in US; 13 in UCL; 14 in LCC). Companion star masses range
from 0.1 to 3 Msun. The mass ratio distribution follows f(q) = q^-0.33, which
excludes random pairing. No close (rho < 3.75'') companion stars or background
stars are found in the magnitude range 12 < Ks < 14. The lack of stars with
these properties cannot be explained by low-number statistics, and may imply a
lower limit on the companion mass of ~ 0.1 Msun. Close stellar components with
Ks > 14 are observed. If these components are very low-mass companion stars, a
gap in the companion mass distribution might be present. The small number of
close low-mass companion stars could support the embryo-ejection formation
scenario for brown dwarfs. Our findings are compared with and complementary to
visual, spectroscopic, and astrometric data on binarity in Sco OB2. We find an
overall companion star fraction of 0.52 in this association. This paper is the
first step toward our goal to derive the primordial binary population in Sco
OB2.


title:
Towards characterization of exoplanetary atmospheres with the VLT
  Interferometer

abstract:
  The direct observation of extrasolar planets and their spectra is coming into
reach with the new generation of ground-based near-IR interferometers, like the
Very Large Telescope Interferometer (VLTI). The high contrast between star and
planet requires an excellent calibration of atmospheric distortions. Proposed
techniques are the observation of color-differential or closure phases. The
differential phase, however, is only in a first order approximation independent
of atmospheric influences because of dispersion effects. This might prevent
differential phase observations of extrasolar planets. The closure phase, on
the other hand, is immune to atmospheric phase errors and is therefore a
promising alternative. We have modeled the response of the closure phase
instrument AMBER at the VLTI to realistic models of known extrasolar planetary
systems taking into account their theoretical spectra as well as the geometry
of the VLTI. We present a strategy to determine the geometry of the planetary
system and the spectrum of the extrasolar planet from closure phase
observations in a deterministic way without any a priori assumptions. We show
that the nulls in the closure phase do only depend on the system geometry but
not on the planetary or stellar spectra. Therefore, the geometry of the system
can be determined by measuring the nulls in the closure phase and braking the
remaining ambiguity due to the unknown system orientation by means of
observations at different hour angles. Based on the known geometry, the planet
spectrum can be directly synthesized from the closure phases.


title:
Starbursts and the triggering of the activity in nearby powerful radio
  galaxies

abstract:
  We present high quality long-slit spectra for three nearby powerful radio
galaxies 3C293, 3C305, PKS1345+12. These were taken with the aim of
characterising the young stellar populations (YSP), and thereby investigating
the evolution of the host galaxies, as well as the events that triggered the
activity. Isochrone spectral synthesis modelling of the wide wavelength
coverage spectra of nuclear and off-nuclear continuum-emitting regions have
been used to estimate the ages, masses and luminosities of the YSP component,
taking full account of reddening effects and potential contamination by
activity-related components. We find that the YSP make a substantial
contribution to the continuum flux in the off-nuclear regions on a radial scale
of 1 - 20kpc in all three objects. Moreover, in two objects we find evidence
for reddened post-starburst stellar populations in the near-nuclear regions of
the host galaxies. The YSP are relatively old (0.1- 2Gyr), massive and make up
a large proportion (~1 - 50%) of the total stellar mass in the regions of
galaxies sampled by the observations. Overall, these results are consistent
with the idea that AGN activity in some radio galaxies is triggered by major
gas-rich mergers. Therefore, these radio galaxies form part of the subset of
early-type galaxies that is evolving most rapidly in the local universe.
Intriguingly, the results also suggest that the radio jets are triggered
relatively late in the merger sequence, and that there is an evolutionary link
between radio galaxies and luminous/ultra-luminous infrared galaxies.


title: The Microarcsecond Sky and Cosmic Turbulence

abstract:
  Radio waves are imprinted with propagation effects from ionized media through
which they pass. Owing to electron density fluctuations, compact sources
(pulsars, masers, and compact extragalactic sources) can display a wide variety
of scattering effects. These scattering effects, particularly interstellar
scintillation, can be exploited to provide *superresolution*, with achievable
angular resolutions (<~ 1 microarcsecond) far in excess of what can be obtained
by very long baseline interferometry on terrestrial baselines. Scattering
effects also provide a powerful sub-AU probe of the microphysics of the
interstellar medium, potentially to spatial scales smaller than 100 km, as well
as a tracer of the Galactic distribution of energy input into the interstellar
medium through a variety of integrated measures. Coupled with future gamma-ray
observations, SKA observations also may provide a means of detecting fainter
compact gamma-ray sources. Though it is not yet clear that propagation effects
due to the intergalactic medium are significant, the SKA will either detect or
place stringent constraints on intergalactic scattering.


title: Generalised cosmological scaling solutions

abstract:
  Motivated by the recent interest in cosmologies arising from energy density
modifications to the Friedmann equation, we analyse the scaling behaviour for a
broad class of these cosmologies comprised of scalar fields and background
barotropic fluid sources. In particular, we determine the corresponding scalar
field potentials which lead to attractor scaling solutions in a wide class of
braneworld and dark energy scenarios. We show how a number of recent proposals
for modifying the Friedmann equation can be thought of as being dual to one
another, and determine the conditions under which such dualities arise.


title:
Testing the Universality of the (U-V) Color-Magnitude Relations for
  Nearby Clusters of Galaxies

abstract:
  We present a detailed U-V CMR analysis for 3 local (z<0.06) Abell (A85, A496,
A754) galaxy clusters, with 637 total spectroscopic members down to 0.1L^star.
We find that these clusters have similar CMRs with a mean color of U-V=1.4 at
M_V=-20+5logh, and narrow limits of intrinsic color scatter [0.047,0.079] and
slope [-0.094,-0.075]. The core cluster population of red galaxies follow CMRs
that are in close agreement with that of Coma. We test how sensitive the CMR
uniformity is to variations in color aperture size and sample selection, and
find slightly wider limits of scatter [0.047,0.112] and slope [-0.104,-0.054].
This upper limit for U-V scatter is consistent with z_form>1.2 for the bulk of
the stars in red cluster galaxies, and a maximum age spread of 5.2 Gyr. We note
that none of the slopes exhibit a break as claimed by Metcalf et al., and using
colors from equal-light apertures does not remove the CMR slope. Our findings
expand the single Coma data point and provide a much-needed z=0 base-line for
comparisons to high-z cluster U-V CMRs. The CMR scatter range in low-z clusters
is consistent with that found in high-z clusters, suggesting little evolution
in the stars of red cluster galaxies out to z~1. To identify the most recently
accreted galaxies, we divide each cluster's membership into 3 galaxy
populations based on CMR-relative U-V color. Blue galaxies make up 18-23% of
each cluster's galaxy counts above 0.1L^star. We test the hypothesis that
CMR-relative color represents rough cluster infall times and find that blue
galaxies are spatially, kinematically, and morphologically distinct from red
cluster members. These distinctions provide further evidence that bluer members
are indeed more recently accreted field spirals as expected in an hierarchical
universe. (abridged)