title:
Modelling the ultraviolet/submillimeter spectral energy distributions of
  normal galaxies

abstract:
  We give an overview of the factors shaping the ultraviolet (UV)/optical -
far-infrared (FIR)/submillimeter (submm) spectral energy distributions (SEDs)
of normal (non-starburst) galaxies. Particular emphasis is placed on the
influen ce of the geometry of dust and stars on the propagation of light
through the int erstellar medium. Although strong constraints can be placed on
the amount and la rge scale distribution of dust in disks from the appearance
of the galaxies in t he optical/UV range, this dust does not account for the
observed amplitude and c olour of the FIR/submm radiation. Additional,
optically thick components of dust associated with the young stellar population
on large and small scales are requ ired to account for the complete UV/optical
- FIR/submm SEDs. Self-consistent mo dels for the calculation of SEDs of spiral
galaxies are reviewed, and their pred ictions for the dust emission and the
attenuation of starlight are compared and contrasted.


title:
The structural and scaling properties of nearby galaxy clusters - II.
  The M-T relation

abstract:
  Using a sample of ten nearby (z< 0.15), relaxed galaxy clusters in the
temperature range [2-9] keV, we have investigated the scaling relation between
the mass at various density contrasts (delta=2500,1000,500,200) and the cluster
temperature. The masses are derived from NFW-type model fits to mass profiles,
obtained under the hydrostatic assumption using precise measurements, with XMM,
at least down to delta=1000. The logarithmic slope of the M-T relation is well
constrained and is the same at all delta, reflecting the self-similarity of the
mass profiles. At delta=500, the slope of the relation for the sub-sample of
hot clusters (kT>3.5 keV) is consistent with the standard self-similar
expectation: alpha= 1.49\pm0.15. The relation steepens when the whole sample is
considered: alpha=1.71\pm0.09. The normalisation of the relation is discrepant
(by ~ 30%), at all density contrasts, with the prediction from purely
gravitation based models. Models that take into account radiative cooling and
galaxy feedback are generally in better agreement with our data. We argue that
remaining discrepancies, in particular at low delta, are more likely due to
problems with models of the ICM thermal structure rather than to an incorrect
estimate of the mass from X-ray data.


title: Dark energy, chaotic fields, and fundamental constants

abstract:
  To explain the currently observed accelerated expansion of the universe, a
large number of different theoretical models are presently being discussed. In
one way or another, all of these contain `new physics', though at different
levels. The big question is how to select out of infinitely many possible
models the right one. Here we discuss a possibility that has so far been
somewhat neglected, namely that the new physics underlying dark energy arises
out of a gravitationally active amendment of the electroweak and strong sector
of the standard model. This amendment basically consists of a rapidly
fluctuating gravitationally active dynamics of vacuum fluctuations with a
cutoff of the order of the neutrino mass scale. We consider a concrete model
for this based on second-quantized self-interacting scalar fields, which evolve
in a chaotic way. It is shown that expectations with respect to the chaotic
dynamics yield statements on the observed numerical values of the electroweak
coupling constants with amazing precision, thus providing evidence for the
physical relevance of this model.


title:
Primordial Magnetic Fields from Out of Equilibrium Cosmological Phase
  Transitions

abstract:
  The universe cools down monotonically following its expansion.This generates
a sequence of phase transitions. If a second order phase transition happens
during the radiation dominated era with a charged order parameter, spinodal
unstabilities generate large numbers of charged particles. These particles
hence produce magnetic fields.We use out of equilibrium field theory methods to
study the dynamics in a mean field or large N setup.The dynamics after the
transition features two distinct stages: a spinodal regime dominated by linear
long wave length instabilities, and a scaling stage in which the
non-linearities and backreaction of the scalar fields are dominant. This second
stage describes the growth of horizon sized domains. We implement a formulation
based on the non equilibrium Schwinger-Dyson equations to obtain the spectrum
of magnetic fields that includes the dissipative effects of the plasma. We find
that large scale magnetogenesis is efficient during the scaling regime. Charged
scalar field fluctuations with wavelengths of the order of the Hubble radius
induce large scale magnetogenesis via loop effects.The leading processes
are:pair production, pair annihilation and low energy bremsstrahlung, these
processes while forbidden in equilibrium are allowed strongly out of
equilibrium. The ratio between the energy density on scales larger than L and
that in the background radiation r(L,T)= rho_B(L,T)/rho_{cmb}(T) is r(L,T) ~
10^{-34} at the Electroweak scale and r(L,T) ~ 10^{-14} at the QCD scale for L
sim 1 Mpc. The resulting spectrum is insensitive to the magnetic diffusion
length and equipartition between electric and magnetic fields does not hold. We
conjecture that a similar mechanism could be operative after the QCD chiral
phase transition.


title: On the survival and disruption of Earth mass CDM micro-haloes

abstract:
  Neutralino dark matter leads to the formation of numerous earth mass dark
matter haloes at redshifts z\approx 60 (Diemand et al. 2005). These abundant
CDM micro-haloes have cuspy density profiles that can easily withstand the
Galactic tidal field at the solar radius. Zhao, Taylor, Silk & Hooper
(astro-ph/0502049) concluded that ``...the majority of dark matter
substructures with masses \sim 10^{-6}M_o will be tidally disrupted due to
interactions with stars in the Galactic halo''. However these authors assumed a
halo density of stars that is at least an order of magnitude higher than
observed. We show that the appropriate application of the impulse approximation
is to the regime of multiple encounters, not single disruptive events as
adopted by Zhao et al., which leads to a survival time of several Hubble times.
Therefore we do not expect the tidal heating by Galactic stars to affect the
abundance of micro-haloes. Disk crossing will cause some mass loss but the
central cores are likely to survive and could be detected as gamma-ray sources
with proper motions of several arc minutes per year.


title: Precursors of UCHII regions & the evolution of massive outflows

abstract:
  Since this contributions was meant to cover two subjects which are both in
the field of massive star formation but which in its details can be discussed
separately, this paper is divided in two sections. First, we present
characteristics of precursors of UCH{\sc ii} regions and their likely
evolutionary properties. The second section discusses massive molecular
outflows, their implications for high-mass star formation, and a possible
evolutionary sequence for massive outflows.


title: Baryons in Dark Matter Halos

abstract:
  We present here the preface and the Table of Content of the Proceedings of
the Conference "Baryons in Dark Matter Halos" held in Cittanova/Novigrad (HR)
on 5-9 October, 2004 and published on-line by PoS (http://pos.sissa.it) which
is a new versatile, online proceedings and lecture notes publication service
launched by SISSA, Trieste.


title:
Spectroscopic Redshifts to z > 2 for Optically Obscured Sources
  Discovered with the Spitzer Space Telescope

abstract:
  We have surveyed a field covering 9.0 degrees^2 within the NOAO Deep
Wide-Field Survey region in Bootes with the Multiband Imaging Photometer on the
Spitzer Space Telescope (SST) to a limiting 24 um flux density of 0.3 mJy.
Thirty one sources from this survey with F(24um) > 0.75 mJy which are optically
very faint (R > 24.5 mag) have been observed with the low-resolution modules of
the Infrared Spectrograph on SST. Redshifts derived primarily from strong
silicate absorption features are reported here for 17 of these sources; 10 of
these are optically invisible (R > 26 mag), with no counterpart in B_W, R, or
I. The observed redshifts for 16 sources are 1.7 < z < 2.8. These represent a
newly discovered population of highly obscured sources at high redshift with
extreme infrared to optical ratios. Using IRS spectra of local galaxies as
templates, we find that a majority of the sources have mid-infrared spectral
shapes most similar to ultraluminous infrared galaxies powered primarily by
AGN. Assuming the same templates also apply at longer wavelengths, bolometric
luminosities exceed 10^13 L(solar).


title: Cosmological Structures behind the Milky Way

abstract:
  This paper provides an update to the review on extragalactic large-scale
structures uncovered in the Zone of Avoidance (ZOA) by Kraan-Korteweg & Lahav
2000, in particular in the Great Attractor region. Emphasis is given to the
penetration of the ZOA with the in 2003 released NIR 2MASX Catalog. The
distribution is little affected by the foreground dust. Galaxies can be
identified to extinction levels of over A(B) < 10m except in the wider Galactic
Bulge region (see Fig. 9) where star density is a strong delimiting factor. The
shape of the NIR-ZOA is quite asymmetric due to Galactic features such as
spiral arms and the Bulge, something that should not be ignored when using NIR
samples for studies such as dipole determinations.
  Results are presented from the deep blind HI ZOA survey performed with the
Multibeam Receiver at the Parkes telescope (v < 12700km/s). The distribution of
the roughly one thousand discovered spiral galaxies in the optically and NIR
impenetratable part of the ZOA clearly depict the prominence of the Norma
Supercluster. With the optically identified galaxies in the ZOA, a picture
emerges that bears a striking resemblance to the Coma cluster in the Great
Wall: the rich Norma cluster (ACO 3627) lies within a great-wall like structure
that can be traced at the redshift range of the cluster over 90dg on the sky,
with two foreground filaments - reminiscent of the legs in the famous stick man
- that merge in an overdensity at slightly lower redshifts around the radio
galaxy PKS 1343-601 (see Figs. 14 & 16). (abridged)


title:
The Radio to Infrared Emission of Very High Redshift Gamma-Ray Bursts:
  Probing Early Star Formation through Molecular and Atomic Absorption Lines

abstract:
  We evaluate the broadband afterglow emission of very high redshift gamma-ray
bursts (GRBs) using standard relativistic blastwave models with both forward
and reverse shock components. For a broad range of parameters, a generic
property for GRBs at redshifts $z \sim$ 5--30 is that the emission peaks in the
millimeter to far-infrared bands with milli-Jansky flux levels, first at a few
hours after the burst due to the reverse shock, and then again for several days
afterwards with somewhat lower flux due to the forward shock. The radio,
submillimeter and infrared continuum emission should be readily detectable out
to $z \ga 30$ by the Atacama Large Millimeter Array (ALMA), Extended Very Large
Array (EVLA), Square Kilometer Array (SKA) and other facilities. For relatively
bright bursts, spectroscopic measurements of molecular and atomic absorption
lines due to ambient protostellar gas may be possible. Utilizing models of
primordial protostellar clouds, we show that under certain conditions,
appreciable absorption may be caused by HD rotational transitions even in
metal-free environments. After sufficient metal enrichment, absorption from CO
rotational transitions and [OI] fine-structure transitions can also become
strong. With appropriate observing strategies in combination with optical
telescopes, ALMA and/or SKA may be able to detect such lines, offering a unique
probe of physical conditions in individual Pop III and early Pop II star
forming regions. We also remark on potential near-infrared absorption features
due to electronic transitions of H$_2$.


title:
Detection of gamma-ray lines from interstellar 60Fe by the high
  resolution spectrometer SPI

abstract:
  It is believed that core-collapse supernovae (CCSN), occurring at a rate
about once per century, have seeded the interstellar medium with long-lived
radioisotopes such as 60Fe (half-life 1.5 Myr), which can be detected by the
gamma rays emitted when they beta-decay. Here we report the detection of the
60Fe decay lines at 1173 keV and 1333 keV with fluxes 3.7 +/- 1.1 x 10(-5) ph
cm(-2) s(-1) per line, in spectra taken by the SPI spectrometer on board
INTEGRAL during its first year. The same analysis applied to the 1809 keV line
of 26Al yielded a line flux ratio 60Fe/26Al = 0.11 +/- 0.03. This supports the
hypothesis that there is an extra source of 26Al in addition to CCSN.


title:
Cosmological Interpretation from High Redshift Clusters Observed Within
  the XMM-Newton $\Omega$-Project

abstract:
  During the last ten years astrophysical cosmology has brought three
remarkable results of deep impact for fundamental physics: the existence of
non-baryonic dark matter, the (nearly) flatness of space, the domination of the
density of the universe by some gravitationally repulsive fluid. This last
result is probably the most revolutionizing one: the scientific review Sciences
has considered twice results on this question as Breakthrough of the Year (for
1998 and 2003). However, direct evidence of dark energy are still rather weak,
and the strength of the standard scenario relies more on the "concordance"
argument rather than on the robustness of direct evidences. Furthermore, a
scenario can be build in an Einstein-de Sitter universe, which reproduces as
well as the concordance model the following various data relevant to cosmology:
WMAP results, large scale structure of the universe, local abundance of massive
clusters, weak lensing measurements, most Hubble constant measurements not
based on stellar indicators. Furthermore, recent data on distant x-ray clusters
obtained from XMM and Chandra indicates that the observed abundances of
clusters at high redshift taken at face value favors an Einstein de Sitter
model and are hard to reconcile with the concordance model. It seems wise
therefore to consider that the actual existence of the dark energy is still an
open question.


title:
Stochastic processes, galactic star formation, and chemical evolution.
  Effects of accretion, stripping, and collisions in multiphase multi-zone
  models

abstract:
  This paper reports simulations allowing for stochastic accretion and mass
loss within closed and open systems modeled using a previously developed
multi-population, multi-zone (halo, thick disk, thin disk) treatment. The star
formation rate is computed as a function of time directly from the model
equations and all chemical evolution is followed without instantaneous
recycling. Several types of simulations are presented here: (1) a closed system
with bursty mass loss from the halo to the thick disk, and from the thick to
the thin disk, in separate events to the thin disk; (2) open systems with
random environmental (extragalactic) accretion, e.g. by infall of high velocity
clouds directly to the thin disk; (3) schematic open system single and multiple
collision events and intracluster stripping. For the open models, the mass of
the Galaxy has been explicitly tracked with time. We present the evolution of
the star formation rate, metallicity histories, and concentrate on the light
elements. We find a wide range of possible outcomes, including an explanation
for variations in the Galactic D/H ratio, and highlight the problems for
uniquely reconstructing star forming histories from contemporary abundance
measurements.


title:
A tensor-vector-scalar framework for modified dynamics and cosmic dark
  matter

abstract:
  I describe a tensor-vector-scalar theory that reconciles the galaxy scale
success of modified Newtonian dynamics (MOND) with the cosmological scale
evidence for CDM. The theory provides a cosmological basis for MOND in the
sense that the predicted phenomenology only arises in a cosmological
background. The theory contains an evolving effective potential, and scalar
field oscillations in this potential comprise the cold dark matter; the de
Broglie wavelength of these soft bosons, however, is sufficiently large that
they cannot accumulate in galaxies. The theory predicts, inevitably, a constant
anomalous acceleration in the outer solar system which, depending upon the
choice of parameters, can be consistent with that detected by the Pioneer
spacecrafts.


title:
Evidence for Primordial Clustering Around the QSO SDSS J1030+0524 at
  z=6.28

abstract:
  We present tentative evidence for primordial clustering, manifested as an
excess of color-selected objects in the field of the QSO SDSS J1030+0524 at
redshift z=6.28. We have selected objects red in i_{775}-z_{850} on the basis
of Hubble Space Telescope Advanced Camera for Surveys imaging of a field
centered on the QSO. Compared to data at comparable depth obtained by the GOODS
survey, we find an excess of objects with (i_{775}-z_{850}) \geq 1.5 in the QSO
field. The significance of the detection is estimated to be ~97% on the basis
of the counts alone and increases to 99.4% if one takes into account the color
distribution. If confirmed this would represent the highest redshift example of
galaxy clustering and would have implications on models for the growth of
structure. Bias-driven clustering of first luminous objects forming in the
highest peaks of the primordial density field is expected in most models of
early structure formation. The redshift of one of the candidates has been found
to be z=5.970 by our spectroscopy with Keck I/LRIS, confirming the validity of
our color selection.


title: Theoretical He I Emissivities in the Case B Approximation

abstract:
  We calculate the He I case B recombination cascade spectrum using improved
radiative and collisional data. We present new emissivities over a range of
electron temperatures and densities. The differences between our results and
the current standard are large enough to have a significant effect not only on
the interpretation of observed spectra of a wide variety of objects but also on
determinations of the primordial helium abundance.


title:
GRMHD Simulations of Disk/Jet Systems: Application to the Inner Engines
  of Collapsars

abstract:
  We have carried out 2D and 3D general relativistic magnetohydrodynamic
simulations of jets launched self-consistently from accretion disks orbiting
Kerr black holes and applied the results to the inner engine of the collapsar
model of gamma-ray bursts. The accretion flow launches energetic jets in the
axial funnel region of the disk/jet system, as well as a substantial coronal
wind. The jets feature knot-like structures of extremely hot,
ultra-relativistic gas; the gas in these knots begins at moderate velocities
near the inner engine, and is accelerated to ultra-relativistic velocities
(Lorentz factors of 50, and higher) by the Lorentz force in the axial funnel.
The increase in jet velocity takes place in an acceleration zone extending to
at least a few hundred gravitational radii from the inner engine. The overall
energetics of the jets are strongly spin-dependent, with high-spin black holes
producing the highest energy and mass fluxes. In addition, with high-spin black
holes, the ultra-relativistic outflow is cylindrically collimated within a few
hundred gravitational radii of the black hole, whereas in the zero- spin case
the jet retains a constant opening angle of approximately 16 degrees. The
simulations also show that the coronal wind, though considerably slower and
colder than the jets, also carries a significant amount of mass and energy.
When simulation data is scaled to the physical dimensions of a collapsar the
jets operate for a period ranging from 0.1 to 1.4 seconds, until the accretion
disk is depleted, delivering $10^{48}$ to $10^{49}$ erg.


title:
The Integrated Sunyaev-Zeldovich Effect as the Superior Method for
  Measuring the Mass of Clusters of Galaxies

abstract:
  We investigate empirical scaling relations between the thermal
Sunyaev-Zeldovich effect (SZE) and cluster mass in simulated clusters of
galaxies. The simulated clusters have been compiled from four different samples
that differ only in their assumed baryonic physics. We show that the strength
of the thermal SZE integrated over a significant fraction of the virialized
region of the clusters is relatively insensitive to the detailed heating and
cooling processes in the cores of clusters by demonstrating that the derived
scaling relations are nearly identical between the four cluster samples
considered. For our synthetic images, the central Comptonization parameter
shows significant boosting during transient merging events, but the integrated
SZE appears to be relatively insensitive to these events. Most importantly, the
integrated SZE closely tracks the underlying cluster mass. Observations through
the thermal SZE allow a strikingly accurate mass estimation from relatively
simple measurements that do not require either parametric modeling or geometric
deprojection and thus avoid assumptions regarding the physics of the ICM or the
symmetry of the cluster. This result offers significant promise for precision
cosmology using clusters of galaxies.


title:
A full sky prediction of the SZ effect from diffuse hot gas in the local
  universe and the upper limit from the WMAP data

abstract:
  We use the PSCz galaxy redshift catalogue combined with constrained
simulations based on the IRAS 1.2 Jy galaxy density field to estimate the
contribution of hot gas in the local universe to the SZ-effect on large scales.
We produce a full sky Healpix map predicting the SZ-effect from clusters as
well as diffuse hot gas within 80Mpc/h. Performing cross-correlation tests
between this map and the WMAP data in pixel, harmonic and wavelet space we can
put an upper limit on the effect. We conclude that the SZ effect from diffuse
gas in the local universe cannot be detected in current CMB data and is not a
contaminating factor on large scales (l<60) in studies of the CMB angular
anisotropies. However, for future high sensitivity experiments observing at a
wider range of frequencies, the predicted large scale SZ effect could be of
importance.


title:
Mass-to-Light Ratios of Field Early-Type Galaxies at z~1 from Ultra-Deep
  Spectroscopy: Evidence for Mass-dependent Evolution

abstract:
  We present an analysis of the Fundamental Plane for a sample of 27 field
early-type galaxies in the redshift range 0.6<z<1.15. The galaxies in this
sample have high S/N spectra obtained at the VLT and high resolution imaging
from the ACS. We find that the mean evolution in M/L of our sample is $Delta ln
(M/L_B) = -1.74+/-0.16z$, with a large galaxy-to-galaxy scatter. This value can
be too low by 0.3 due to selection effects, resulting in $Delta ln (M/L_B) =
-1.43+/-0.16z$. The strong correlation between M/L and rest-frame color
indicates that the observed scatter is not due to measurement errors, but due
to intrinsic differences between the stellar populations of the galaxies. This
pace of evolution is much faster than the evolution of cluster galaxies.
However, we find that the measured M/L evolution strongly depends on galaxy
mass. For galaxies with masses $M>2 x 10^11 Msol$, we find no significant
difference between the evolution of field and cluster galaxies: $Delta ln
(M/L_B) = -1.20+/-0.18z for field galaxies and $Delta ln (M/L_B) =
-1.12+/-0.06z$ for cluster galaxies. The relation between the measured M/L
evolution and mass is partially due to selection effects. However, even when
taking selection effects into account, we still find a relation between M/L
evolution and mass, which is most likely caused by a lower mean age and a
larger intrinsic scatter for low mass galaxies. Results from lensing early-type
galaxies, which are mass-selected, show a very similar trend with mass. This,
combined with our findings, provides evidence for down-sizing. Previous studies
of the rate of evolution of field early-type galaxies found a large range of
mutually exclusive values. We show that these differences are largely caused by
the differences between fitting methods. (Abridged)


title: Diverse Albedos of Small Trans-Neptunian Objects

abstract:
  Discovery of transneptunian object (TNO) satellites and determination of
their orbits has recently enabled estimation of the size and albedo of several
small TNOs, extending the size range of objects having known size and albedo
down into the sub-100 km range. In this paper we compute albedo and size
estimates or limits for 20 TNOs, using a consistent method for all binary
objects and a consistent method for all objects having reported thermal fluxes.
As is true for larger TNOs, the small objects show a remarkable diversity of
albedos. Although the sample is limited, there do not yet appear to be any
trends relating albedo to other observable properties or to dynamical class,
with the possible exception of inclination. The observed albedo diversity of
TNOs has important implications for computing the size-frequency distribution,
the mass, and other global properties of the Kuiper belt derived from
observations of objects' apparent magnitudes and may also point the way toward
an improved compositional taxonomy based on albedo in addition to color.


title:
Third-order perturbative solutions in the Lagrangian perturbation theory
  with pressure

abstract:
  Lagrangian perturbation theory for cosmological fluid describes structure
formation in the quasi-nonlinear stage well. We present a third-order
perturbative equation for Lagrangian perturbation with pressure in both the
longitudinal and transverse modes. Then we derive the perturbative solution for
simplest case.


title:
How Concentrated Are The Haloes Of Low Surface Brightness Galaxies In
  The Cold Dark Matter Model?

abstract:
  We investigate whether a correlation exists between the concentration and
spin parameters of dark matter haloes forming in LCDM N-body simulations. In
particular, we focus on haloes with virial masses characteristic of the hosts
of Low Surface Brightness (LSB) and High Surface Brightness (HSB) galaxies. Our
analysis demonstrates that concentration and spin are anti-correlated. If we
assume that a galaxy disk forms in one of these haloes from baryons that
approximately conserved angular momentum during their dissipation into the
rotationally supported disk, then it is possible to estimate the disk's central
surface density. For an appropriate choice of mass-to-light ratio, we can place
constraints on the central surface brightness of the disk and hence identify
the analogues of the host haloes of LSB and HSB galaxies. We find that our LSB
galaxy analogues occupy haloes that have lower concentrations than might be
expected based on consideration of the mass-concentration relation for the LCDM
cosmology. The distribution of concentrations peaks at c~6, in good agreement
with observational data, although there are important differences between the
shapes of the simulated and observationally inferred distributions. This
suggests that LSB galaxies inhabit a biased subsample of the halo population,
and that this bias may be an important ingredient for resolving the current
debate regarding the structure of LSB galaxy dark matter haloes.


title: Supernova neutrino challenges

abstract:
  A principal `supernova neutrino challenge' is the computational difficulty of
six-dimensional neutrino radiation hydrodynamics. The variety of resulting
approximations has provoked a long history of uncertainty in the core-collapse
supernova explosion mechanism, but recent work highlighting low-mode convection
and a newly-recognized instability in spherical accretion shocks may signal
(yet another) resolution. As part of its goal of elucidating the explosion
mechanism, the Terascale Supernova Initiative is committed to meeting the full
complexity of the computational challenge. The understanding of supernova
neutrino emission gained in detailed simulations provides a potential basis for
learning about two major remaining unknowns in neutrino flavor mixing: the
value of the mixing angle $\theta_{13}$, and distinguishing between ``normal''
and ``inverted'' mass hierarchies.


title: Symmetric hyperbolic Euler equations for relativistic perfect fluids

abstract:
  The Euler equations governing a relativistic perfect fluid are put into
symmetric hyperbolic form with dependent variables the fluid's specific entropy
plus a generalized velocity vector equal to the fluid's unit relativistic
velocity vector divided pointwise by the fluid's specific enthalpy.


title: New Cosmology with Clusters of Galaxies

abstract:
  The review summarizes present and future applications of galaxy clusters to
cosmology with emphasis on nearby X-ray clusters. The discussion includes the
density of dark matter, the normalization of the matter power spectrum,
neutrino masses, and especially the equation of state of the dark energy, the
interaction between dark energy and ordinary matter, gravitational holography,
and the effects of extra-dimensions.


title: A Search for Very Active Stars in the Galaxy

abstract:
  We report the first results of a systematic search near the plane of the
Galaxy for the so called very active stars (VAS), which are characterized by a
hard X-ray spectrum and activity in the radio domain. Candidates with hard
X-ray binary-like spectra have been selected from the Bright ROSAT Source
Catalogue in the Zone of Avoidance ($| b | < 20{^o}$) and were tentatively
identified in GB6/PMM/NVSS radio surveys. Most of them were observed with the
ATCA and VLA. Precise radio coordinates have led to unambiguous optical
identification for 60 candidates, and a sub-sample of five of themhas been
observed with the VLT. Also some discovery and confirmatory spectra were
obtained with the AAT (4-m) and BTA (6-m). Spectroscopy with moderate
dispersion, made with the FORS1 spectrograph of the VLT has revealed two
stellar objects (one of them, VASC J1628-41, is definitivelya binary VAS), one
new AGN and two featureless spectrum sources. One of these objects, VASC
J1353-66, shows a marginal evidence of proper motion, which, if confirmed,
would imply the discovery of a new type of galactic source.


title: A "pulsational" distance determination for the Large Magellanic Cloud

abstract:
  We present results from the theoretical modelling of the observed B,V light
curves of 14 RR Lyrae stars in the Large Magellanic Cloud. The sample includes
7 fundamental and 7 first overtone pulsators covering the metallicity range
from -2.12 to -0.79 dex in [Fe/H], with average value of -1.54 dex. Masses,
intrinsic luminosities, effective temperatures, and reddenings were derived by
fitting high accuracy multiband light curves available for these RR Lyrae stars
to nonlinear convective pulsation models. Individual distance moduli were
determined for each variable, they lead to an average distance modulus for the
Large Magellanic Cloud of (m-M)o= 18.54 +/-0.02 (sigm= 0.09 mag, standard
deviation of the average), in good agreement with the "long" astronomical
distance scale.


title: The axis of evil

abstract:
  We examine previous claims for a preferred axis at $(b,l)\approx (60,-100)$
in the cosmic radiation anisotropy, by generalizing the concept of multipole
planarity to any shape preference (a concept we define mathematically).
Contrary to earlier claims, we find that the amount of power concentrated in
planar modes for $\ell=2,3$ is not inconsistent with isotropy and Gaussianity.
The multipoles' alignment, however, is indeed anomalous, and extends up to
$\ell=5$ rejecting statistical isotropy with a probability in excess of 99.9%.
There is also an uncanny correlation of azimuthal phases between $\ell=3$ and
$\ell=5$. We are unable to blame these effects on foreground contamination or
large-scale systematic errors. We show how this reappraisal may be crucial in
identifying the theoretical model behind the anomaly.


title: Disk-averaged Spectra & light-curves of Earth

abstract:
  We are using computer models to explore the observational sensitivity to
changes in atmospheric and surface properties, and the detectability of
biosignatures, in the globally averaged spectra and light-curves of the Earth.
Using AIRS (Atmospheric Infrared Sounder) data, as input for atmospheric and
surface properties, we have generated spatially resolved high-resolution
synthetic spectra using the SMART radiative transfer model, for a variety of
conditions, from the UV to the far-IR (beyond the range of current Earth-based
satellite data). We have then averaged over the visible disk for a number of
different viewing geometries to quantify the sensitivity to surface types and
atmospheric features as a function of viewing geometry, and spatial and
spectral resolution.
  These results have been processed with an instrument simulator to improve our
understanding of the detectable characteristics of Earth-like planets as viewed
by the first generation extrasolar terrestrial planet detection and
characterization missions (Terrestrial Planet Finder/Darwin and Life finder).
The wavelength range of our results are modelled over are applicable to both
the proposed visible coronograph and mid-infrared interferometer TPF
architectures.
  We have validated this model against disk-averaged observations by the Mars
Global Surveyor Thermal Emission Spectrometer (MGS TES).
  This model was also used to analyze Earth-shine data for detectability of
planetary characteristics and biosignatures in disk-averaged spectra.


title:
Upper limits to the SN1006 multi-TeV gamma-ray flux from H.E.S.S.
  observations

abstract:
  Observations of the shell-type supernova remnant SN1006 have been carried out
with the H.E.S.S. system of Cherenkov telescopes during 2003 (18.2h with two
operating telescopes) and 2004 (6.3h with all four telescopes). No evidence for
TeV gamma-ray emission from any compact or extended region associated with the
remnant is seen and resulting upper limits at the 99.9% confidence level are up
to a factor 10 lower than previously-published fluxes from CANGAROO. For SN1006
at its current epoch of evolution we give limits for a number of important
global parameters. Upper limits on the gamma-ray luminosity (for E=0.26 to 10
TeV, distance d=2 kpc) of L_gamma < 1.7x10^{33} erg s^{-1}, and the total
energy in corresponding accelerated protons, W_p<1.6\times 10^{50} erg (for
proton energies E_p \sim 1.5 to 60 TeV and assuming the lowest value n=0.05
cm^{-3} of the ambient target density discussed in literature) are estimated.
Extending this estimate to cover the range of proton energies observed in the
cosmic ray spectrum up to the knee (we take here E_p ~ 1 GeV to 3 PeV, assuming
a differential particle index -2) gives W_p<6.3x10^{50} erg. A lower limit on
the post-shock magnetic field of B>25microG results when considering the
synchrotron/inverse-Compton framework for the observed X-ray flux and gamma-ray
upper limits.


title:
Probing the Magnetic Field at Sub-Parsec Radii in the Accretion Disk of
  NGC 4258

abstract:
  We present an analysis of polarimetric observations at 22 GHz of the water
vapor masers in NGC 4258 obtained with the VLA and the GBT. We do not detect
any circular polarization in the spectrum indicative of Zeeman-induced
splitting of the maser lines of water, a non-paramagnetic molecule. We have
improved the 1-sigma upper limit estimate on the toroidal component of the
magnetic field in the circumnuclear disk of NGC 4258 at a radius of 0.2 pc from
300 mG to 90 mG. We have developed a new method for the analysis of spectra
with blended features and derive a 1-sigma upper limit of 30 mG on the radial
component of the magnetic field at a radius of 0.14 pc. Assuming thermal and
magnetic pressure balance, we estimate an upper limit on the mass accretion
rate of ~10^(-3.7) M_sun/yr for a total magnetic field of less than 130 mG. We
discuss the ramifications of our results on current maser models proposed to
explain the observed maser emission structure and the consequences for current
accretion theories. We find from our magnetic field limits that the thin-disk
model and the jet-disk model are better candidates for accounting for the
extremely low-luminosity nature of NGC 4258, than models that include
advection-dominated accretion flows.


title: A Physical Model for the Origin of Quasar Lifetimes

abstract:
  We propose a model of quasar lifetimes in which observational quasar
lifetimes and an intrinsic lifetime of rapid accretion are strongly
distinguished by the physics of obscuration by surrounding gas and dust.
Quasars are powered by gas funneled to galaxy centers, but for a large part of
the accretion lifetime are heavily obscured by the large gas densities powering
accretion. In this phase, starbursts and black hole growth are fueled but the
quasar is buried. Eventually, feedback from accretion energy disperses
surrounding gas, creating a window in which the black hole is observable
optically as a quasar, until accretion rates drop below those required to
maintain a quasar luminosity. We model this process and measure the unobscured
and intrinsic quasar lifetimes in a hydrodynamical simulation of a major galaxy
merger. The source luminosity is determined from the black hole accretion rate,
calculated from local gas properties. We calculate the column density of
hydrogen to the source along multiple lines of sight and use these column
densities and gas metallicities to determine B-band attenuation of the source.
Defining the observable quasar lifetime as the total time with an observed
B-band luminosity above some limit L_B,min, we find lifetimes ~10-20 Myr for
L_B,min=10^11 L_sun (M_B=-23), in good agreement with observationally
determined quasar lifetimes. This is significantly smaller than the intrinsic
lifetime ~100 Myr obtained if attenuation is neglected. The ratio of observed
to intrinsic lifetime is also strong function of both the limiting luminosity
and the observed frequency.


title:
X-ray Absorption Line Spectroscopy of the Galactic Hot Interstellar
  Medium

abstract:
  We present an X-ray absorption line spectroscopic study of the large-scale
hot interstellar medium (HISM) in the Galaxy. We detect Ne IX K$_\alpha$
absorption lines in the {\sl Chandra} grating spectra of seven Galactic
low-mass X-ray binaries. Three of these sources also show absorption of O VII
K$_\alpha$, O VII K$_\beta$, and/or O VIII K$_\alpha$. Both centroid and width
of the lines are consistent with a Galactic HISM origin of the absorption. By
jointly fitting the multiple lines, accounting for line saturation and assuming
the collisional ionization equilibrium, we estimate the average absorbing gas
temperature as $\sim 2.4\pm0.3\times10^6$ K (90% confidence errors). We further
characterize the spatial density distribution of the gas as ${\rm
6.4_{-1.7}^{+2.4} exp(-|z|/1.2_{-0.5}^{+1.0} kpc) \times10^{-3}{\rm cm^{-3}}} $
(a disk morphology) or ${\rm 6.2_{-2.1}^{+3.8} [ 1 + (R/2.3_{-1.1}^{+1.6}
kpc)^2]^{-1} \times10^{-3} {\rm cm^{-3}}}$ (a sphere morphology), where $z$ and
$R$ are the distances from the Galactic plane and Galactic center (GC)
respectively. Since nearly all the sight-lines with significant absorption
lines detected are somewhat toward GC and at low Galactic latitudes, these
results could be severely biased. More observations toward off-GC sight-lines
and at high latitudes are urgently needed to further the study. Nevertheless,
the results demonstrate the excellent potential of X-ray absorption line
spectroscopy in the study of the HISM.


title: Dark Energy Constraints from the CTIO Lensing Survey

abstract:
  We perform a cosmological parameter analysis of the 75 square degree CTIO
lensing survey in conjunction with CMB and Type Ia supernovae data. For Lambda
CDM cosmologies, we find that the amplitude of the power spectrum at low
redshift is given by sigma_8 = 0.81 (+0.15,-0.10, 95% c.l.), where the error
bar includes both statistical and systematic errors. The total of all
systematic errors is smaller than the statistical errors, but they do make up a
significant fraction of the error budget. We find that weak lensing improves
the constraints on dark energy as well. The (constant) dark energy equation of
state parameter, w, is measured to be -0.89 (+0.16,-0.21, 95% c.l.).
Marginalizing over a constant $w$ slightly changes the estimate of sigma_8 to
0.79 (+0.17, -0.14, 95% c.l.). We also investigate variable w cosmologies, but
find that the constraints weaken considerably; the next generation surveys are
needed to obtain meaningful constraints on the possible time evolution of dark
energy.


title: Neutrinos: the Key to UHE Cosmic Rays

abstract:
  Observations of ultrahigh energy cosmic rays (UHECR) do not uniquely
determine both the injection spectrum and the evolution model for UHECR sources
- primarily because interactions during propagation obscure the early Universe
from direct observation. Detection of neutrinos produced in those same
interactions, coupled with UHECR results, would provide a full description of
UHECR source properties.


title:
Diffusive Synchrotron Radiation from Relativistic Shocks of Gamma-Ray
  Burst Sources

abstract:
  The spectrum of electromagnetic emission generated by relativistic electrons
scattered on small-scale random magnetic fields, implied by current models of
the magnetic field generation in the gamma-ray burst sources, is considered.
The theory developed includes both perturbative and non-perturbative versions
and, therefore, suggests a general treatment of the radiation in arbitrary
small-scale random field. It is shown that a general treatment of the random
nature of the small-scale magnetic field, as well as angular diffusion of the
electrons due to multiple scattering by magnetic inhomogeneities (i.e.,
non-perturbative effects), give rise to a radiation spectrum that differs
significantly from so-called "jitter" spectrum. The spectrum of diffusive
synchrotron radiation seems to be consistent with the low energy spectral index
distribution of the gamma-ray bursts.


title:
Towards an understanding of the rapid decline of the cosmic star
  formation rate

abstract:
  We present a first analysis of deep 24 micron observations with the Spitzer
Space Telescope of a sample of nearly 1500 galaxies in a thin redshift slice,
0.65<z<0.75. We combine the infrared data with redshifts, rest-frame
luminosities, and colors from COMBO-17, and with morphologies from Hubble Space
Telescope images collected by the GEMS and GOODS projects. To characterize the
decline in star-formation rate (SFR) since z~0.7, we estimate the total thermal
infrared (IR) luminosities, SFRs, and stellar masses for the galaxies in this
sample. At z~0.7, nearly 40% of intermediate and high-mass galaxies (with
stellar masses >2x10^10 solar masses) are undergoing a period of intense star
formation above their past-averaged SFR. In contrast, less than 1% of
equally-massive galaxies in the local universe have similarly intense star
formation activity. Morphologically-undisturbed galaxies dominate the total
infrared luminosity density and SFR density: at z~0.7, more than half of the
intensely star-forming galaxies have spiral morphologies, whereas less than
\~30% are strongly interacting. Thus, a decline in major-merger rate is not the
underlying cause of the rapid decline in cosmic SFR since z~0.7. Physical
properties that do not strongly affect galaxy morphology - for example, gas
consumption and weak interactions with small satellite galaxies - appear to be
responsible.


title: High Redshift Supernovae: Cosmological Implications

abstract:
  We review the findings for the values of the cosmological parameters as
derived from high-redshift SNIa measurements. The most recent results confirm
the picture of a non-empty inflationary Universe that is consistent with a
cosmological constant Omega_Lambda~0.7. This implies that the expansion of the
Universe is currently accelerated by the action of some mysterious dark energy.
We also discuss the possibility and the consequences of the fact that SNIa may
not be "perfect" standard candles, in the sense of having properties in the
early Universe that are systematically different from those they have at the
present times.


title: Statistical isotropy of CMB anisotropy from WMAP

abstract:
  The statistical expectation values of the temperature fluctuations of cosmic
microwave background (CMB) are assumed to be preserved under rotations of the
sky. We investigate the statistical isotropy of the CMB anisotropy maps
recently measured by the Wilkinson Microwave Anisotropy Probe (WMAP) using
bipolar spherical harmonic power spectrum proposed in Hajian & Souradeep 2003.
The Bipolar Power Spectrum (BiPS) is estimated for the full sky CMB anisotropy
maps of the first year WMAP data. The method allows us to isolate regions in
multipole space and study each region independently. This search shows no
evidence for violation of statistical isotropy in the first-year WMAP data on
angular scales larger than that corresponding to l~60.


title: Summary of ICGC04 Cosmology Workshop

abstract:
  Cosmology is passing through a golden phase of rapid advance. The cosmology
workshop at ICGC-2004 attracted a large number of research contributions from
diverse topics of cosmology. I attempt to classify and summarize the research
work and results of the oral and poster presentations made at the meeting.


title: Testing Stellar Models With An Improved Physical Orbit for 12 Bootis

abstract:
  We report on a significantly improved determination of the physical orbit of
the double-lined spectroscopic binary system 12 Boo. We have a 12 Boo
interferometry dataset spanning six years with the Palomar Testbed
Interferometer, a smaller amount of data from the Navy Prototype Optical
Interferometer, and a radial velocity dataset spanning 14 years from the
Harvard-Smithsonian Center for Astrophysics. We have updated the 12 Boo
physical orbit model with our expanded interferometric and radial velocity
datasets. The revised orbit is in good agreement with previous results, and the
physical parameters implied by a combined fit to our visibility and radial
velocity data result in precise component masses and luminosities. In
particular, the orbital parallax of the system is determined to be 27.74 $\pm$
0.15 mas, and masses of the two components are determined to be 1.4160 $\pm$
0.0049 M$_{\sun}$ and 1.3740 $\pm$ 0.0045 M$_{\sun}$, respectively. Based on
theoretical models we can estimate a system age of approximately 3.2 Gyr.
Comparisons with stellar models suggest that the 12 Boo primary may be just
entering the Hertzsprung gap, but that conclusion is highly dependent on
details of the models. Such a dynamic evolutionary state makes the 12 Boo
system a unique and important test for stellar models.


title: Time correlations of high energy muons in an underground detector

abstract:
  We present the result of a search for correlations in the arrival times of
high energy muons collected from 1995 till 2000 with the streamer tube system
of the complete MACRO detector at the underground Gran Sasso Lab. Large samples
of single muons (8.6 million), double muons (0.46 million) and multiple muons
with multiplicities from 3 to 6 (0.08 million) were selected. These samples
were used to search for time correlations of cosmic ray particles coming from
the whole upper hemisphere or from selected space cones. The results of our
analyses confirm with high statistics a random arrival time distribution of
high energy cosmic rays.


title: The near-infrared size-luminosity relations for Herbig Ae/Be disks

abstract:
  We report the results of a sensitive K-band survey of Herbig Ae/Be disk sizes
using the 85-m baseline Keck Interferometer. Targets were chosen to span the
maximum range of stellar properties to probe the disk size dependence on
luminosity and effective temperature. For most targets, the measured
near-infrared sizes (ranging from 0.2 to 4 AU) support a simple disk model
possessing a central optically-thin (dust-free) cavity, ringed by hot dust
emitting at the expected sublimation temperatures (T_sub~1000-1500K).
Furthermore, we find a tight correlation of disk size with source luminosity R
propto L^(1/2) for Ae and late Be systems (valid over more than 2 decades in
luminosity), confirming earlier suggestions based on lower-quality data.
Interestingly, the inferred dust-free inner cavities of the highest luminosity
sources (Herbig B0-B3 stars) are under-sized compared to predictions of the
optically-thin cavity model, likely due to optically-thick gas within the inner
AU.


title: Neutralino annihilation in the Large Magellanic Cloud

abstract:
  I present results with respect to the gamma-ray and synchrotron fluxes due to
neutralino annihilation in the Large Magellanic Cloud based on Tasitsiomi et
al., Astrop. Phys. 21, 637 (2004).


title: Coronographic Methods for the Detection of Terrestrial Planets

abstract:
  This report summarizes the current status of efforts to develop the
technologies required for coronographic space missions aimed at the detection
of terrestrial extrasolar planets.


title:
Neural Networks as a Composition Diagnostic for Ultra-high Energy Cosmic
  Rays

abstract:
  We analyze here the possibility of studying mass composition in the Auger
data sample using neural networks as a diagnostic tool. Extensive air showers
were simulated using the AIRES code, for the two hadronic interaction models in
current use: QGSJet and Sibyll. Both, photon and hadron primaries were
simulated and used to generate events. The output parameters from the ground
array were simulated for the typical instrumental and environmental conditions
at the Malarg\"ue Auger site using the code SAMPLE. Besides photons, hydrogen,
helium, carbon, oxygen, magnesium, silicon, calcium and iron nuclei were also
simulated. We show that Principal Components Analysis alone is enough to
separate individual photon from hadron events, but the same technique cannot be
applied to the classification of hadronic events. The latter requires the use
of a more robust diagnostic. We show that neural networks are potentially
powerful enough to discriminate proton from iron events almost on an
event-by-event basis. However, in the case of a more realistic multi-component
mixture of primary nuclei, only a statistical estimate of the average mass can
be reliably obtained. Although hybrid events are not explicitly simulated, we
show that, whenever hybrid information in the form of $X_{max}$ is introduced
in the training procedure of the neural networks, a considerable improvement
can be achieved in mass discrimination analysis.


title:
The Interpretation of Inertial Force and The Existence of Absolute
  Background

abstract:
  The formalism of classical particle dynamics is reinvestigated according to
the basic requirement of causal consistency, and a new equation of particle
dynamics, which is more general and more in line with classical mechanics
experiments than Newton's second law, is obtained. More importantly, the
inertial frame of reference is no longer required and the inertial force is no
longer introduced by hand. The new dynamical equation can be straightforwardly
applied in any reference frame as long as which is irrotational with respect to
the absolute background of the universe. The nature of the inertial force is
nothing but the real forces acting on the reference object. The essence of this
reform of classical particle dynamics is just a drawback of traditional
formalism in Newtonian mechanics being corrected. However, it may be more
important that a logical derivation of this new particle dynamics equation
strongly suggests the existence of an absolute background for the whole space
of the universe. In physical concepts, the absolute background for space does
not conflict with the relative length of the base unit of space in Einstein's
Special Relativity and General Relativity. Furthermore, the size of the base
unit of space should essentially be understood as the length of the line
segment, which is cut from the absolute background of space by the intrinsic
physical events.


title:
The HIPASS catalogue: Omega_HI and environmental effects on the HI mass
  function of galaxies

abstract:
  We use the catalogue of 4315 extragalactic HI 21-cm emission line detections
from HIPASS to calculate the most accurate measurement of the HI mass function
(HIMF) of galaxies to date. The completeness of the HIPASS sample is well
characterised, which enables an accurate calculation of space densities. The
HIMF is fitted with a Schechter function with parameters: alpha=-1.37 +/- 0.03
+/- 0.05, log (M_HI/M_sun=9.80 +/- 0.03 +/- 0.03, and theta*=(6.0 +/- 0.8 +/-
0.6) x 10^{-3} Mpc^{-3} (random and systematic uncertainties at 68% CL, H0=75),
in good agreement with calculations based on the HIPASS Bright Galaxy
Catalogue, which is a complete, but smaller, sub-sample of galaxies. The
cosmological mass density of HI in the local universe is found to be
Omega_HI=(3.5 +/- 0.4 +/- 0.4) x 10^{-4}. This large homogeneous sample allows
us to test whether the shape of the HIMF depends on local galaxy density. We
find tentative evidence for environmental effects in the sense that the HIMF
becomes steeper toward higher density regions, ranging from alpha ~ -1.2 in the
lowest density environments to alpha ~ -1.5 in the highest density environments
probed by this blind HI survey. This effect appears stronger when densities are
measured on larger scales.


title:
From Young and Hot to Old and Cold: Comparing White Dwarf Cooling Theory
  to Main Sequence Stellar Evolution in Open Clusters

abstract:
  I explore the current ability of both white dwarf cooling theory and main
sequence stellar evolution theory to accurately determine stellar population
ages by comparing ages derived using both techniques for open clusters ranging
from 0.1 to 4 Gyr. I find good agreement between white dwarf and main sequence
evolutionary ages over the entire age range currently available for study. I
also find that directly comparing main sequence turn-off ages to white dwarf
ages is only weakly sensitive to realistic levels of errors in cluster
distance, metallicity, and reddening. Additional detailed comparisons between
white dwarf and main sequence ages have tremendous potential to refine and
calibrate both of these important clocks, and I present new simulations of
promising open cluster targets. The most demanding requirement for these white
dwarf studies are very deep (V > 25-28) cluster observations made necessary by
the faintness of the oldest white dwarfs.


title: Abell 370: A Cluster with a Pronounced Triaxial Morphology

abstract:
  We here combine Sunyaev-Zel'dovich effect, X-ray observations and
spectroscopic redshifts of member galaxies, to constrain the intrinsic
three-dimensional shape of the galaxy cluster: Abell 370. The cluster turns out
to be strongly elongated along the l.o.s., with two (or more) substructures in
the process of merging. Spectroscopy further suggests that the process must be
taking place at a small angle respect to the l.o.s.


title: The Nature of Nonthermal X-ray Filaments Near the Galactic Center

abstract:
  Recent Chandra and XMM-{\it Newton} observations reported evidence of two
X-ray filaments G359.88-0.08 (SgrA-E) and G359.54+0.18 (the ripple filament)
near the Galactic center. The X-ray emission from these filaments has a
nonthermal spectrum and coincides with synchrotron emitting radio sources.
Here, we report the detection of a new X-ray feature coincident with a radio
filament G359.90-0.06 (SgrA-F) and show more detailed VLA, Chandra and BIMA
observations of the radio and X-ray filaments. In particular, we show that
radio emission from the nonthermal filaments G359.90-0.06 (SgrA-F) and
G359.54+0.18 (the ripple) has a steep spectrum whereas G359.88-0.08 (SgrA-E)
has a flat spectrum. The X-ray emission from both these sources could be due to
synchrotron radiation. However, given that the 20 \kms molecular cloud, with
its intense 1.2mm dust emission, lies in the vicinity of SgrA-F, it is possible
that the X-rays could be produced by inverse Compton scattering of far-infrared
photons from dust by the relativistic electrons responsible for the radio
synchrotron emission. The production of X-ray emission from ICS allows an
estimate of the magnetic field strength of ~0.08 mG within the nonthermal
filament. This should be an important parameter for any models of the Galactic
center nonthermal filaments.


title: Kinematics of Ionised Gas in the Barred Seyfert Galaxy NGC 4151

abstract:
  We have determined the structure and kinematics of ionised gas in the weak
oval bar of the archetypal Seyfert 1 galaxy, NGC 4151, using the TAURUS
Fabry-Perot interferometer to simultaneously map the distribution and
kinematics of Hbeta emission. We also present broad-band ultraviolet imaging of
the host galaxy, obtained with XMM-Newton, that shows the detailed distribution
of star formation in the bar and in the optically-faint outer spiral arms. We
compare the distribution and kinematics of ionised gas with that previously
determined in neutral hydrogen by Mundell & Shone; we suggest that the
distribution of bright, patchy UV emission close to the HI shocks is consistent
with ionisation by star clusters that have formed in compressed pre-shock gas.
These clusters then travel ballistically through the gaseous shock to ionise
gas downstream along the leading edge of the bar. In addition, we detect, for
the first time, ionised gas within the shock itself which is streaming to
smaller radii in the same manner as the neutral gas.


title: Probing the curvature and dark energy

abstract:
  Two new one-parameter tracking behavior dark energy representations
$\omega=\omega_0/(1+z)$ and $\omega=\omega_0 e^{z/(1+z)}/(1+z)$ are used to
probe the geometry of the Universe and the property of dark energy. The
combined type Ia supernova (SN Ia), Sloan Digital Sky Survey (SDSS), and
Wilkinson Microwave Anisotropy Probe (WMAP) data indicate that the Universe is
almost spatially flat and that dark energy contributes about 72% of the matter
content of the present universe. The observational data also tell us that
$\omega(0)\sim -1$. It is argued that the current observational data can hardly
distinguish different dark energy models to the zeroth order. The transition
redshift when the expansion of the Universe changed from deceleration phase to
acceleration phase is around $z_{\rm T}\sim 0.6$ by using our one-parameter
dark energy models.


title: Absence of linear polarization in Halpha emission of solar flares

abstract:
  High sensitivity observations of Halpha polarization of 30 flares of
different sizes and disk positions are reported. Both filter and spectrographic
techniques have been used. The ZIMPOL system eliminates spurious polarizations
due to seeing and flat-field effects. We didn't find any clear linear
polarization signature above our sensitivity level which was usually better
than 0.1%. The observations include an X17.1 flare with gamma-ray lines
reported by the RHESSI satellite. These results cast serious doubts on previous
claims of linear polarization at the one percent level and more, attributed to
impact polarization. The absence of linear polarization limits the anisotropy
of energetic protons in the H$\alpha$ emitting region. The likely causes are
isotropization by collisions with neutrals in the chromosphere and defocusing
by the converging magnetic field.


title: Photoionized Lines in the X-ray Spectra of SMC X-1

abstract:
  We present a detailed spectral analysis of Chandra/ACIS-S CC mode
observations of the massive X-ray binary system SMC X-1. The system was
observed during both the high and low X-ray states of the roughly 60-day
superorbital period. The continuum spectra during both states are well
represented by a power law with photon index $\alpha$=0.9 and a blackbody of kT
= 0.15keV. The high state spectra are dominated by the continuum and
independent of orbital phase whereas the low state spectra show a strong
orbital dependence as well as line emission from O, Ne, Mg, Fe, and Si. This is
consistent with the states attributed to disk precession: during the high state
X-ray emission is dominated by the compact source which is abrubtly eclipsed
and during the low state the compact object is hidden by the disk and a larger,
less luminous scattering region is responsible for the X-ray emission. A
prominent Ne IX feature places a stringent limit (Log $\xi$ = 2.0-2.5) on the
ionization parameter which constrains the wind dynamics of the system. The Fe
line fluxes are related linearly to the blackbody fluxes indicating that both
originate in the same region or are excited by the same mechanism. There is
evidence for structure in the Fe-line that cannot be fully resolved by the
current observations. The pulse period measured during our observations,
0.7057147$\pm$0.00000027s shows that the uninterrupted spin-up trend of SMC X-1
continues. We discuss the implications of our results for models of SMC X-1.


title: A Radio Monitoring Survey of Ultra-Luminous X-Ray Sources

abstract:
  We present the results of a radio monitoring campaign to search for radio
emission from nearby ultra-luminous X-ray sources (ULXs). These sources are
bright off-nuclear X-ray point sources with luminosities exceeding L_X > 10^39
erg/sec. A well-defined sample of the 9 nearest ULXs has been monitored eight
times during 5 months with the Very Large Array in A and B configuration. Our
limiting sensitivity is approximately 0.15 mJy (4 sigma) for radio flares and
around 60 uJy for continuous emission. In M82 two ULXs seem to have coincident
compact radio sources, which are probably supernova remnants. No continuous or
flaring radio emission has been detected from any other ULX. Thus, ULXs do not
generally emit steady-state radio emission above radio powers of 1.5 10^17
W/Hz. The non-detections of the continuous emission are consistent with beamed
or unbeamed radio emission from accreting black holes of <= 10^3 Msol based on
the radio/X-ray correlation. Other published radio detections (M82, NGC 5408)
are also discussed in this context. Both detections are significantly above our
detection limit. If ULXs have flaring radio emission above 4 10^17 W/Hz we can
give an upper limit on the duty circle of the flares of 6%. This upper limit is
in agreement with the observed number of flares in Galactic radio transients.
Additionally we present a yet unreported radio double structure in the nearby
low-luminosity AGN NGC 4736.


title:
The Propeller Regime of Disk Accretion to a Rapidly Rotating Magnetized
  Star

abstract:
  The propeller regime of disk accretion to a rapidly rotating magnetized star
is investigated here for the first time by axisymmetric 2.5D
magnetohydrodynamic simulations. An expanded, closed magnetosphere forms in
which the magnetic field is predominantly toroidal. A smaller fraction of the
star's poloidal magnetic flux inflates vertically, forming a magnetically
dominated tower. Matter accumulates in the equatorial region outside
magnetosphere and accretes to the star quasi-periodically through elongated
funnel streams which cause the magnetic field to reconnect. The star spins-down
owing to the interaction of the closed magnetosphere with the disk. For the
considered conditions, the spin-down torque varies with the angular velocity of
the star omega* as omega*^1.3 for fixed mass accretion rate. The propeller
stage may be important in the evolution of X-ray pulsars, cataclysmic variables
and young stars. In particular, it may explain the present slow rotation of the
classical T Tauri stars.


title: A simple model for the complex lag structure of microquasars

abstract:
  The phase lag structure between the hard and soft X-ray photons observed in
GRS 1915+105 and XTE J1550+564 has been said to be ``complex'' because the
phase of the Quasi-Periodic Oscillation fundamental Fourier mode changes with
time and because the even and odd harmonics signs behave differentely.
  From simultaneous X-ray and radio observations this seems to be related to
the presence of a jet (level of radio emission). We propose a simple idea where
a partial absorption of the signal can shift the phases of the Fourier modes
and account for the phase lag reversal. We also briefly discuss a possible
physical mechanism that could lead to such an absorption of the quasi-periodic
oscillation modulation.


title: A New View of the Circumstellar Environment of SN 1987A

abstract:
  We summarize the analysis of a uniform set of both previously-known and
newly-discovered scattered-light echoes, detected within 30" of SN 1987A in ten
years of optical imaging, and with which we have constructed the most complete
three-dimensional model of the progenitor's circumstellar environment.
Surrounding the SN is a richly-structured bipolar nebula. An outer,
double-lobed ``peanut,'' which we believe is the contact discontinuity between
the red supergiant and main sequence winds, is a prolate shell extending 28 ly
along the poles and 11 ly near the equator. Napoleon's Hat, previously believed
to be an independent structure, is the waist of this peanut, which is pinched
to a radius of 6 ly. Interior, the innermost circumstellar material lies along
a cylindrical hourglass, 1 ly in radius and 4 ly long, which connects to the
peanut by a thick equatorial disk. The nebulae are inclined 41o south and 8o
east of the line of sight, slightly elliptical in cross section, and marginally
offset west of the SN. The 3-D geometry of the three circumstellar rings is
studied, suggesting the equatorial ring is elliptical (b/a<0.98), and spatially
offset in the same direction as the hourglass. Dust-scattering models suggest
that between the hourglass and bipolar lobes: the gas density drops from 1--3
cm^{-3} to >0.03 cm^{-3}; the maximum dust-grain size increases from ~0.2
micron to 2 micron; and the Si:C dust ratio decreases. The nebulae have a total
mass of ~1.7 Msun, yielding a red-supergiant mass loss around 5*10^{-6} Msun
yr^{-1}.


title: A quasi-time-dependent radiative transfer model of OH104.9+2.4

abstract:
  We investigate the pulsation-phase dependent properties of the circumstellar
dust shell (CDS) of the OH/IR star OH104.9+2.4 based on radiative transfer
modeling (RTM) using the code DUSTY. Our previous study concerning simultaneous
modeling of the spectral energy distribution (SED) and near-infrared (NIR)
visibilities (Riechers et al. 2004) has now been extended by means of a more
detailed analysis of the pulsation-phase dependence of the model parameters of
OH104.9+2.4. In order to investigate the temporal variation in the spatial
structure of the CDS, additional NIR speckle interferometric observations in
the K' band were carried out with the 6 m telescope of the Special
Astrophysical Observatory (SAO). At a wavelength of 2.12 micron the
diffraction-limited resolution of 74 mas was attained. Several key parameters
of our previous best-fitting model had to be adjusted in order to be consistent
with the newly extended amount of observational data. It was found that a
simple rescaling of the bolometric flux F_bol is not sufficient to take the
variability of the source into account, as the change in optical depth over a
full pulsation cycle is rather high. On the other hand, the impact of a change
in effective temperature T_eff on SED and visibility is rather small. However,
observations, as well as models for other AGB stars, show the necessity of
including a variation of T_eff with pulsation phase in the radiative transfer
models. Therefore, our new best-fitting model accounts for these changes.


title: Cooling Active Region Loops Observed With SXT and TRACE

abstract:
  An Impulsive Heating Multiple Strand (IHMS) Model is able to reproduce the
observational characteristics of EUV (~ 1 MK) active region loops. This model
implies that some of the loops must reach temperatures where X-ray filters are
sensitive (> 2.5 MK) before they cool to EUV temperatures. Hence, some bright
EUV loops must be preceded by bright X-ray loops. Previous analysis of X-ray
and EUV active region observations, however, have concluded that EUV loops are
not preceded by X-ray loops. In this paper, we examine two active regions
observed in both X-ray and EUV filters and analyze the evolution of five loops
over several hours. These loops first appear bright in the X-ray images and
later appear bright in the EUV images. The delay between the appearance of the
loops in the X-ray and EUV filters is as little as 1 hour and as much as 3
hours. All five loops appear as single ``monolithic'' structures in the X-ray
images, but are resolved into many smaller structures in the (higher
resolution) EUV images. The positions of the loops appear to shift during
cooling implying that the magnetic field is changing as the loops evolve. There
is no correlation between the brightness of the loop in the X-ray and EUV
filters meaning a bright X-ray loop does not necessarily cool to a bright EUV
loop and vice versa. The progression of the loops from X-ray images to EUV
images and the observed substructure is qualitatively consistent with the IMHS
model.


title: Are There Local Analogs of Lyman Break Galaxies?

abstract:
  To make direct comparisons in the rest-far-ultraviolet between LBGs at z~3
and more local star-forming galaxies, we use HST/STIS to image a set of 12
nearby (z<0.05) HII galaxies in the FUV and a set of 14 luminous compact blue
galaxies (LCBGs) at moderate redshift (z~0.5) in the NUV, corresponding to the
rest-FUV. We then subject both sets of galaxy images and those of LBGs at z~3
to the same morphological and structural analysis. We find many qualitative and
quantitative similarities between the rest-FUV characteristics of distant LBGs
and of the more nearby starburst samples, including general morphologies,
sizes, asymmetries, and concentrations. Along with some kinematic similarities,
this implies that nearby HII galaxies and LCBGs may be reasonable local analogs
of distant Lyman break galaxies.


title:
Dynamical and Spectral Modeling of the Ionized Gas and Nuclear
  Environment in NGC 3783

abstract:
  We present a new approach for calculating the physical properties of highly
ionized X-ray flows in active galactic nuclei (AGN). Our method relies on a
detailed treatment of the structure, dynamics and spectrum of the gas. A
quantitative comparison of our model predictions with the 900 ksec Chandra/HETG
X-ray spectrum of NGC 3783 shows that: (1) The highly ionized outflow is driven
by thermal pressure gradients and radiation pressure force is less important.
(2) A full featured dynamical model that provides a very good fit to the high
resolution X-ray spectrum requires a multi-phased flow with a density power
spectrum reminiscent of the interstellar medium. (3) Adiabatic cooling is an
important factor and so is an additional heating source that may be related to
the apparent multi-phase and turbulent nature of the flow. (4) The base of the
flow is ~1pc from the central object, in agreement with some, but not all
previous estimates. (5) The mass loss rate is in the range 0.01-0.1 solar
masses per year which is smaller than previous estimates and of the same order
of the mass accretion rate in this object.


title:
The Sun's Dust Disk -- Discovery Potential of the New Horizons mission
  during Interplanetary Cruise

abstract:
  The dust disk detected by Pioneer at a heliocentric distance of 18 AU is a
fraction of the dust generated by the Kuiper belt outside 30 AU. New Horizons
will find a very high flux of more than 10 hits per day for each square meter
of sensitive area.


title: RETROCAM: A Versatile Optical Imager for Synoptic Studies

abstract:
  We present RETROCAM, an auxiliary CCD camera that can be rapidly inserted
into the optical beam of the MDM 2.4m telescope. The speed and ease of
reconfiguring the telescope to use the imager and a straightforward user
interface permit the camera to be used during the course of other observing
programs. This in turn encourages RETROCAM's use for a variety of monitoring
projects.


title: The case for a distributed solar dynamo shaped by near-surface shear

abstract:
  Arguments for and against the widely accepted picture of a solar dynamo being
seated in the tachocline are reviewed and alternative ideas concerning dynamos
operating in the bulk of the convection zone, or perhaps even in the
near-surface shear layer, are discussed. Based on the angular velocities of
magnetic tracers it is argued that the observations are compatible with a
distributed dynamo that may be strongly shaped by the near-surface shear layer.
Direct simulations of dynamo action in a slab with turbulence and shear are
presented to discuss filling factor and tilt angles of bipolar regions in such
a model.


title: Neptune Trojans as a Testbed for Planet Formation

abstract:
  The problem of accretion in the Trojan 1:1 resonance is akin to the standard
problem of planet formation, transplanted from a star-centered disk to a disk
centered on the Lagrange point. The newly discovered class of Neptune Trojans
promises to test theories of planet formation by coagulation. Neptune Trojans
resembling the prototype 2001 QR322 (``QR'')--whose radius of ~100 km is
comparable to that of the largest Jupiter Trojan--may outnumber their Jovian
counterparts by a factor of ~10. We discover that seeding the 1:1 resonance
with debris from planetesimal collisions and having the seed particles accrete
in situ naturally reproduces the inferred number of QR-sized Trojans. We
analyze accretion in the Trojan sub-disk by applying the two-groups method,
accounting for kinematics specific to the resonance. We find that a Trojan
sub-disk comprising decimeter-sized seed particles and having a surface density
1e-3 that of the local minimum-mass disk produces ~10 QR-sized objects in ~1
Gyr, in accord with observation. Further growth is halted by collisional
diffusion of seed particles out of resonance. In our picture, the number and
sizes of the largest Neptune Trojans represent the unadulterated outcome of
dispersion-dominated, oligarchic accretion. Large Neptune Trojans, perhaps the
most newly accreted objects in our Solar System, may today have a dispersion in
orbital inclination of less than ~10 degrees, despite the existence of niches
of stability at higher inclinations. Such a vertically thin disk, born of a
dynamically cold environment necessary for accretion, and raised in minimal
contact with external perturbations, contrasts with the thick disks of other
minor body belts.


title: The proto--neutron--star dynamo -- viability and impediments

abstract:
  We study convective motions taken from hydrodynamic simulations of rotating
proto--neutron stars (PNSs) with respect to their ability to excite a dynamo
instability which may be responsible for the giant neutron star magnetic
fields. Since it is impossible to simulate the magnetic field evolution
employing the actual magnetic Reynolds numbers ($\Rm$) resulting from the
hydrodynamic simulations, (smallest) critical $\Rm$s and the corresponding
field geometries are derived on the kinematic level by rescaling the velocity
amplitudes. It turns out that the actual values of $\Rm$ are by many orders of
magnitude larger than the critical values found. A dynamo might therefore start
to act vigorously very soon after the onset of convection. But as in general
dynamo growth rates are non--monotonous functions of $\Rm$ the later fate of
the magnetic field is uncertain. Hence, no reliable statements on the existence
and efficiency of PNS dynamos can be drawn without considering the interplay of
magnetic field and convection from the beginning. Likewise, in so far as
convection inside the PNS is regarded to be essential in re--launching the
supernova explosion, a revision of its role in this respect could turn out to
be necessary.


title:
Searching for O$_2$ in the SMC:Constraints on Oxygen Chemistry at Low
  Metallicities

abstract:
  We present a 39 h integration with the Odin satellite on the ground-state
118.75 GHz line of O2 towards the region of strongest molecular emission in the
Small Magellanic Cloud. Our 3sigma upper limit to the O2 integrated intensity
of <0.049 K km/s in a 9'(160 pc) diameter beam corresponds to an upper limit on
the O2/H2 abundance ratio of <1.3E-6. Although a factor of 20 above the best
limit on the O2 abundance obtained for a Galactic source, our result has
interesting implications for understanding oxygen chemistry at sub-solar metal
abundances. We compare our abundance limit to a variety of astrochemical models
and find that, at low metallicities, the low O2 abundance is most likely
produced by the effects of photo-dissociation on molecular cloud structure.
Freeze-out of molecules onto dust grains may also be consistent with the
observed abundance limit, although such models have not yet been run at
sub-solar initial metallicities.


title: The XENON Dark Matter Experiment

abstract:
  The XENON experiment aims at the direct detection of dark matter in the form
of WIMPs (Weakly Interacting Massive Particles) via their elastic scattering
off Xenon nuclei. With a fiducial mass of 1000 kg of liquid xenon, a
sufficiently low threshold of ~16 keV recoil energy and an un-rejected
background rate of 10 events per year, XENON would be sensitive to a
WIMP-nucleon interaction cross section of 10^(-46) cm^2, for WIMPs with masses
above 50 GeV. The 1 tonne scale experiment (XENON1T) will be realized with an
array of ten identical 100 kg detector modules (XENON100). The detectors are
time projection chambers operated in dual (liquid/gas) phase, to detect
simultaneously the ionization, through secondary scintillation in the gas, and
primary scintillation in the liquid produced by low energy recoils. The
distinct ratio of primary to secondary scintillation for nuclear recoils from
WIMPs (or neutrons), and for electron recoils from background, is key to the
event-by-event discrimination capability of XENON. A 3kg dual phase detector
with light readout provided by an array of 7 photomultipliers is currently
being tested, along with other prototypes dedicated to various measurements
relevant to the XENON program. We present some of the results obtained to-date
and briefly discuss the next step in the phased approach to the XENON
experiment, i.e. the development and underground deployment of a 10 kg detector
(XENON10) within 2005.


title: Galactic Chemical Evolution Redux: Atomic Numbers 6 < Z < 15

abstract:
  Motivated by the inability of Galactic chemical evolution models to reproduce
some of the observed solar neighbourhood distribution of elements (and
isotopes) with atomic numbers 6 < Z < 15, we have revisited the relevant
stellar and Galactic models as part of an ambitious new program aimed at
resolving these long-standing discrepancies. Avoiding the use of (traditional)
parametric models for low- and intermediate-mass stellar evolution, we have
generated a new, physically self-consistent, suite of stellar models and
integrated the nucleosynthetic outputs into GEtool, our semi-analytical
galactic chemical evolution software package. The predicted temporal evolution
of several light- and intermediate-mass elements (and their isotopes) in the
solar neighbourhood - from carbon to phosphorus - demonstrate the efficacy of
the new yields in reconciling theory and observation.


title: Wide-field weak lensing by RXJ1347-1145

abstract:
  We present an analysis of weak lensing observations for RXJ1347-1145 over a
43' X 43' field taken in B and R filters on the Blanco 4m telescope at CTIO.
RXJ1347-1145 is a massive cluster at redshift z=0.45. Using a population of
galaxies with 20<R<26, we detect a weak lensing signal at the p<0.0005 level,
finding best-fit parameters of \sigma_v=1400^{+130}_{-140} km s^{-1} for a
singular isothermal sphere model and r_{200} = 3.5^{+0.8}_{-0.2} Mpc with c =
15^{+64}_{-10} for a NFW model in an \Omega_m = 0.3, \Omega_\Lambda = 0.7
cosmology. In addition, a mass to light ratio M/L_R =90 \pm 20 M_\odot /
L_{R\odot} was determined. These values are consistent with the previous weak
lensing study of RXJ1347--1145 by Fischer and Tyson, 1997, giving strong
evidence that systemic bias was not introduced by the relatively small field of
view in that study. Our best-fit parameter values are also consistent with
recent X-ray studies by Allen et al, 2002 and Ettori et al, 2001, but are not
consistent with recent optical velocity dispersion measurements by Cohen and
Kneib, 2002.


title:
A semi-relativistic approach to the circular restricted three body
  problem and a numerical experiment around the 3:2 resonance

abstract:
  A Hamiltonian that approaches the study of the three-body problem in general
relativity is obtained. We use it to study the relativistic version of the
circular restricted three-body problem in which the first body is the heaviest
and the third body is a test-particle. We focus on the orbits around the 3:2
resonance. We show that, in spite of the notable difference between the
relativistic and Newtonian orbits, most of the resonant region is preserved.
Nevertheless, differently from the Newtonian case, the frequencies between the
second and the third body are no longer commensurable.


title: Magnetic field generation from cosmological perturbations

abstract:
  In this letter, we discuss generation of magnetic field from cosmological
perturbations. We consider the evolution of three component plasma (electron,
proton and photon) evaluating the collision term between elecrons and photons
up to the second order. The collision term is shown to induce electric current,
which then generate magnetic field. There are three contributions, two of which
can be evaluated from the first-order quantities, while the other one is fluid
vorticity which is purely second order. We estimate the magnitudes of the
former contributions and shows that the amplitude of the produced magnetic
field is about $\sim 10^{-19} {\rm G}$ at 10Mpc comoving scale at the
recombination. Compared to astrophysical and inflationary mechanisms for
seed-field generation, our study suffers from much less ambiguities concerning
unknown physics and/or processes.


title: The density structure around quasars from optical depth statistics

abstract:
  We present a method for studying the proximity effect and the density
structure around redshift z=2-3 quasars. It is based on the probability
distribution of Lyman-alpha pixel optical depths and its evolution with
redshift.
  We validate the method using mock spectra obtained from hydrodynamical
simulations, and then apply it to a sample of 12 bright quasars at redshifts
2-3 observed with UVES at the VLT-UT2 Kueyen ESO telescope. These quasars do
not show signatures of associated absorption and have a mean monochromatic
luminosity of 5.4 10^{31} h^{-2} erg/s/Hz at the Lyman limit. The observed
distribution of optical depth within 10 Mpc/h from the QSO is statistically
different from that measured in the general intergalactic medium at the same
redshift. Such a change will result from the combined effects of the increase
in photoionisation rate above the mean UV-background due to the extra ionizing
photons from the quasar radiation (proximity effect), and the higher density of
the IGM if the quasars reside in overdense regions (as expected from biased
galaxy formation). The first factor decreases the optical depth whereas the
second one increases the optical depth, but our measurement cannot distinguish
a high background from a low overdensity. An overdensity of the order of a few
is required if we use the amplitude of the UV-background inferred from the mean
Lyman-$\alpha$ opacity. If no overdensity is present, then we require the
UV-background to be higher, and consistent with the existing measurements based
on standard analysis of the proximity effect.


title: Low Mass Star Formation in the Gum Nebula: The CG~30/31/38 complex

abstract:
  We present photometric and spectroscopic results for the low mass pre-main
sequence (PMS) stars with spectral types K - M in the cometary globule (CG)
30/31/38 complex. We obtained multi-object high resolution spectra for the
targets selected as possible PMS stars from multi-wavelength photometry. We
identified 11 PMS stars brighter than V = 16.5 with ages < 5 Myr at a distance
of approximately 200 pc. The spatial distribution of the PMS stars, CG clouds,
and ionizing sources (O stars and supernova remnants) suggests a possible
triggered origin of the star formation in this region. We confirm the youth of
the photometrically selected PMS stars using the lithium abundances. The radial
velocities of the low mass PMS stars are consistent with those of the cometary
globules. Most of the PMS stars show weak Halpha emission with W(Halpha) < 10
A. Only 1 out of the 11 PMS stars shows a moderate near-IR excess, which
suggests a short survival time (t < 5 Myr) of circumstellar disks in this star
forming environment. In addition, we find five young late type stars and one Ae
star which have no obvious relation to the CG 30/31/38 complex. We also discuss
a possible scenario of star formation history in the CG 30/31/38 region.


title: The Formation of Galactic Bulges

abstract:
  We summarise some recent results about nearby galactic bulges that are
relevant to their formation. We highlight a number of significant advances in
our understanding of the surface brightness profiles, stellar populations, and
especially the very centers of spiral galaxies. We also view our own Milky Way
as if it were an external galaxy. Our main conclusions are that bulges of
early-type spirals (S0 -- Sb) contain central nuclear components, just like
late-type spirals and most other types of galaxies. The luminosities of these
central components correlate best with total bulge luminosity, and not as well
with morphological type. Bulges of early-type spiral galaxies follow the
fundamental plane and the colour/line strength vs. luminosity relations of
elliptical galaxies. Although we have a reasonable idea about bulges of
early-type spirals we know much less about late-type bulges. However, the close
resemblance of our Milky Way Bulge to bulges in external disk galaxies makes us
suspect that bulges of late-type spirals might be very similar as well.


title:
Dust Growth and Settling in Protoplanetary Disks and Disk Spectral
  Energy Distributions. I. Laminar Disks

abstract:
  Dust growth and settling considerably affect the spectral energy
distributions (SEDs) of protoplanetary disks. We investigated dust growth and
settling in protoplanetary disks through numerical simulations to examine
time-evolution of the disk optical thickness and SEDs. In the present paper, we
considered laminar disks as a first step of a series of papers. As a result of
dust growth and settling, a dust layer forms around the mid-plane of a gaseous
disk. After the formation of the dust layer, small dust grains remain floating
above the layer. Although the surface density of the floating small grains is
much less than that of the dust layer, they govern the disk optical thickness
and the emission. The floating small grains settle onto the dust layer in a
long time scale compared with the formation of the dust layer. Rapid grain
growth in the inner part of disks makes the radial distribution of the disk
optical thickness less steep than that of the disk surface density. At t >
10^6yr, the optical thickness of the inner disk (> a few AU) almost vanishes,
which may correspond to disk inner holes observed by Spitzer Space Telescope.
Furthermore, we examined time-evolution of disk SEDs, using our numerical
results and the two-layer model. The grain growth and settling decrease the
magnitude of the SEDs especially. Our results indicate that grain growth and
settling can explain the decrease in observed energy fluxes at
millimeter/sub-millimeter wavelengths with time scales of 10^{6-7}yr without
depletion of the disks.


title: Anisotropic mass ejection in binary mergers

abstract:
  We investigate the mass loss from a rotationally distorted envelope following
the early, rapid in-spiral of a companion star inside a common envelope. For
initially wide, massive binaries (M_1+M_2=20M_{\odot}, P\sim 10 yr), the
primary has a convective envelope at the onset of mass transfer and is able to
store much of the available orbital angular momentum in its expanded envelope.
Three-dimensional smoothed particle hydrodynamics calculations show that mass
loss is enhanced at mid-latitudes due to shock reflection from a torus-shaped
outer envelope. Mass ejection in the equatorial plane is completely suppressed
if the shock wave is too weak to penetrate the outer envelope in the equatorial
direction (typically when the energy deposited in the star is less than about
one-third of the binding energy of the envelope). We present a parameter study
to show how the geometry of the ejecta depends on the angular momentum and the
energy deposited in the envelope during a merging event. Applications to the
nearly axisymmetric, but very non-spherical nebulae around SN1987A and Sheridan
25 are discussed, as well as possible links to RY Scuti and the Small
Magellanic Cloud object R4.


title:
Systematic uncertainties in the analysis of star cluster parameters
  based on broad-band imaging observations

abstract:
  (ABRIDGED) We assess the systematic uncertainties in (young) cluster age,
mass, and - to a lesser extent - extinction and metallicity determinations,
based on broad-band imaging observations with the Hubble Space Telescope. Our
aim here is to intercompare the results obtained using a variety of commonly
used modelling techniques, specifically with respect to our own extensively
tested multi-dimensional approach. Any significant differences among the
resulting parameters are due to the details of the various, independently
developed modelling techniques used, rather than to the stellar population
models themselves. Despite the model uncertainties and the selection effects
inherent to most methods used, we find that the PEAKS in the relative age and
mass distributions of a given young (<= 10^9 yr) cluster system can be derived
relatively robustly and consistently, to accuracies of sigma_t = Delta <log(Age
/ yr)> <= 0.35 and sigma_M = Delta <log(M_cl / Msun)> <= 0.14, respectively,
assuming Gaussian distributions in cluster ages and masses for reasons of
simplicity. The peaks in the relative mass distributions can be obtained with a
higher degree of confidence than those in the relative age distributions, as
exemplified by the smaller spread among the peak values of the mass
distributions derived. This implies that mass determinations are mostly
insensitive to the approach adopted. We reiterate that as extensive a
wavelength coverage as possible is required to obtain robust and internally
consistent age and mass estimates for the individual objects, with reasonable
uncertainties. Finally, we conclude that the ACTUAL filter systems used for the
observations should be used for constructing model colours, instead of using
conversion equations, to achieve more accurate derivations of ages and masses.


title: The Nature of Ultra Luminous X-ray Sources

abstract:
  We present spectroscopic observations of six optical counterparts of
intermediate luminosity X-ray sources (ULXs) around nearby galaxies. The
spectra of the six objects show the presence of broad emission features. The
identification of these allow us to classify all of the objects as quasars at
higher redshift than their assigned parent galaxy. This is one of the first and
largest identifications of such objects using unambigous optical spectral
features. These results, in conjuction with previous similar identifications of
other sources, indicate that high redshift quasars represent an important
fraction of catalogued ULX sources. We estimate the density of such sources and
compare this with expectations for a population of randomly distributed
background quasars.


title: Molecular hydrogen formation on grain surfaces

abstract:
  We reconsider H2 formation on grain surfaces. We develop a rate equation
model which takes into account the presence of both physisorbed and chemisorbed
sites on the surface, including quantum mechanical tunnelling and thermal
diffusion. In this study, we took into consideration the uncertainties on the
characteristics of graphitic surfaces. We calculate the H2 formation efficiency
with the Langmuir Hinshelwood and Eley Rideal mechanisms, and discuss the
importance of these mechanisms for a wide range of grain and gas temperatures.
We also develop a Monte Carlo simulation to calculate the H2 formation
efficiency and compare the results to our rate equation models. Our results are
the following: (1) Depending on the barrier against chemisorption, we predict
the efficiency of H2 formation for a wide range of grain and gas temperatures.
(2) The Eley-Rideal mechanism has an impact on the H2 formation efficiency at
high grain and gas temperatures. (3) The fact that we consider chemisorption in
our model makes the rate equation and Monte Carlo approaches equivalent.


title: Luminosity and mass functions of galactic open clusters: II. NGC 4852

abstract:
  e present wide field deep UBVI photometry for the previously unstudied open
cluster NGC 4852 down to a limiting magnitude $I\sim24$, obtained from
observations taken with the Wide Field Imager camera on-board the MPG/ESO 2.2m
telescope at La Silla (ESO, Chile). These data are used to obtain the first
estimate of the cluster basic parameters, to study the cluster spatial
extension by means of star counts, and to derive the Luminosity (LF) and Mass
Function (MF). The cluster radius turns out to be $5.0\pm1.0$ arcmin. The
cluster emerges clearly from the field down to V=20 mag. At fainter magnitud
es, it is completely confused with the general Galactic disk field. The stars
inside this region define a young open cluster (200 million years old) 1.1 kpc
far from the Sun (m-M = 11.60, E(B-V) = 0.45). The Present Day Mass Functions
(PDMF) from the $V$ photometry is one of the most extended in mass insofar
obtained, and can be represented as a power-law with a slope $\alpha =
2.3\pm0.3$ and (the Salpeter (1955) MF in this notation has a slope $\alpha =
2.35$), in the mass range $3.2 \leq \frac{m}{m_{\odot}} \leq 0.6$. Below this
mass, the MF cannot be considered as representative of the cluster MF, as the
cluster merges with the field and therefore the MF is the result of the
combined effect of strong irregularities in the stellar background and
interaction of the cluster with the dense Galactic field. The cluster total
mass at the limiting magnitude results to be 2570$\pm$210 M$_{\odot}$.


title: Interferometric Observations of V838 Monocerotis

abstract:
  We have used long-baseline near-IR interferometry to resolve the peculiar
eruptive variable V838 Mon and to provide the first direct measurement of its
angular size. Assuming a uniform disk model for the emission we derive an
apparent angular diameter at the time of observations (November-December 2004)
of $1.83 \pm 0.06$ milli-arcseconds. For a nominal distance of $8\pm2$ kpc,
this implies a linear radius of $1570 \pm 400 R_{\odot}$. However, the data are
somewhat better fit by elliptical disk or binary component models, and we
suggest that the emission may be strongly affected by ejecta from the outburst.


title: Variable Star Candidates in an ACS Field of M31

abstract:
  A search for variable stars is performed using two epochs of Hubble Space
Telescope (HST) Advanced Camera for Surveys (ACS) imaging data for a 9.28
square arcminute portion of M31. This data set reveals 254 sources that vary by
at least 4-sigma between epochs. The positions and 2-epoch B-band (equivalent)
photometry of these sources are presented. The photometry suggests that this
catalog includes most of the RR Lyrae population of this portion of M31.


title: O/H in the Local Bubble

abstract:
  We present new measurements of the oxygen gas-phase abundance along four
sightlines probing gas inside the Local Bubble, using data obtained with the
Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble Space Telecope
(HST). Combining these with seven previously published N(O I) and N(H I)
measurements we determine a mean O/H ratio for the Local Bubble, (O/H) = (3.45
+/- 0.19)x10^(-4) (1 sigma in the mean). Our result is virtually identical to
O/H = (3.43 +/- 0.15)x10^(-4) derived from data for sightlines probing gas well
outside the Local Bubble. In contrast to the D/O and D/H ratios, which seem to
have different values beyond the Local Bubble, our results show that the O/H
ratio is constant and single-valued both inside and outside the Local Bubble,
for low density sightlines, with column densities up to log N (H) ~ 21. In
addition, the similarity of the two values above suggests that the net effect
of the uncertain O I f-values in the FUSE bandpass is not significant. Taking
into account the latest determinations of the Solar abundance of oxygen, our
result implies that ~25% of the oxygen in the Local Bubble is depleted onto
dust grains. The similarity of the value for O/H along low average density
sightlines in the Local Bubble with that of denser sightlines beyond may permit
a limit on the diluting effects of infalling low metallicity gas.


title: The mass of the black hole in 3C 273

abstract:
  In this paper we apply the reverberation method to determine the mass of the
black hole in 3C273 from the Ly a and C iv emission lines using archival IUE
observations. Following the standard assumptions of the method, we find a
maximum-likelihood estimate of the mass of 6.59 10^9 Mo, with a 1 sigma
confidence interval 5.69-8.27 10^9 Mo. This estimate is more than one order of
magnitude larger than that obtained in a previous study using Balmer lines. We
reanalyze the optical data and show that the method applied to the Ha, Hb, and
Hg Balmer lines produce mass estimates lower by a factor 2.5, but already much
larger than the previous estimate derived from the same lines. The finding of
such a high mass in a face-on object is a strong indication that the gas motion
is not confined to the accretion disk. The new mass estimate makes 3C273
accreting with an accretion rate about six times lower than the Eddington rate.
We discuss the implications of our result for the broad-line-region size and
black-hole mass vs luminosity relationships for the set of objects for which
reverberation black-hole masses have been obtained. We find that, while objects
with super-Eddington luminosities might theoretically be possible, their
existence is not necessarily implied by this sample.