title:
Evolution at z>0.5 of the X-ray properties of simulated galaxy clusters:
  comparison with the observational constraints

abstract:
  (ABRIDGED) We analyze the X-ray properties of a sample of local and high
redshift galaxy clusters extracted from a large cosmological hydrodynamical
simulation. This simulation has been realized using the Tree+SPH code GADGET-2
for a LambdaCDM model. In our analysis, we consider only objects with T_ew >2
keV and adopt an approach that mimics observations, associating with each
measurement an error comparable with recent observations and providing best-fit
results via robust techniques. Within the clusters, baryons are distributed
among (i) a cold neutral phase, with a relative contribution that increases
from less than 1 to 3 per cent at higher redshift, (ii) stars which contribute
with about 20 per cent and (iii) the X-ray emitting plasma that contributes by
80 (76) per cent at z=0 (1) to the total baryonic budget. A depletion of the
cosmic baryon fraction of ~7 (at z=0) and 5 (at z=1) per cent is measured at
the virial radius, R_vir, in good agreement with adiabatic hydrodynamical
simulations. We confirm that, also at redshift >0.5, power-law relations hold
between gas temperature, T, bolometric luminosity, L, central entropy, S, gas
mass, M_gas, and total gravitating mass, M_tot and that these relations are
steeper than predicted by simple gravitational collapse. A significant,
negative evolution in the L-T and L-M_tot relations and positive evolution in
the S-T relation are detected at 0.5 < z < 1 in this set of simulated galaxy
clusters. This is partially consistent with recent analyses of the observed
properties of z>0.5 X-ray galaxy clusters. By fixing the slope to the values
predicted by simple gravitational collapse, we measure at high redshift
normalizations lower by 10-40 per cent in the L-T, M_tot-T, M_gas-T, f_gas-T
and L-M_tot relations than the observed estimates.


title: New light on Dark Cosmos

abstract:
  Recent studies by a number of independent collaborations, have correlated the
CMB temperatures measured by the WMAP satellite with different galaxy surveys
that trace the matter distribution with light from the whole range of the
electromagnetic spectrum: radio, far-infrared, optical and X-ray surveys. The
new data systematically finds positive correlations, indicating a rapid slow
down in the growth of structure in the universe. Individual cross-correlation
measurements are of low significance, but we show that combining data at
different redshifts introduces important new constraints. Contrary to what
happens at low redshifts, for a fixed $\Omm$, the higher the dark energy
contend, $\Ol$, the lower the ISW cross-correlation amplitude. At 68%
confidence level, the data finds new independent evidence of dark energy: $\Ol
=0.42-1.22$ . It also confirms, to higher significance, the presence of a large
dark matter component: $\Omm =0.18-0.34$, exceeding the density of baryonic
matter, but far from the critical value. Combining these new constraints with
the prior of a flat universe, or the prior of an accelerating universe provides
strong new evidence for a dark cosmos. Combination with supernova data yields
$\Ol = 0.71 \pm 0.13$, $\Omm = 0.29 \pm 0.04$. If we also assume a flat
universe, we find $\Ol = 0.70 \pm 0.05$ and $w = -1.02 \pm 0.17$ for a constant
dark energy equation of state.


title: Revisiting the Magnification of Type Ia Supernovae with SDSS

abstract:
  We cross-correlate the sample of Type Ia supernovae from Riess et al. (2004)
with the SDSS DR2 photometric galaxy catalogue. In contrast to recent work, we
find no detectable correlation between supernova magnitude and galaxy
overdensity on scales ranging between 1 and 10 arcminutes. Our results are in
accord with theoretical expectations for gravitational lensing of supernovae by
large-scale structure. Future supernova surveys like SNAP will be capable of
detecting unambiguously the predicted lensing signal.


title: Connecting Cosmology and Colliders

abstract:
  The broad connections between cosmology and collider physics, particularly
precision measurements at the high-energy frontier, are discussed. These
proceedings summarize a colloquium delivered to a general audience of
experimental and theoretical particle and collider physicists at the
International Conference on Linear Colliders (LCWS2004) in Paris.


title:
The X-ray Outburst of H1743-322: High-Frequency QPOs with a 3:2
  Frequency Ratio

abstract:
  We observed the 2003 X-ray outburst of H1743-322 in a series of 130 pointed
observation with RXTE. We searched individual observations for high-frequency
QPOs (HFQPOs) and found only weak or marginal detections near 240 and 160 Hz.
We next grouped the observations in several different ways and computed the
average power-density spectra (PDS) in a search for further evidence of HFQPOs.
This effort yielded two significant results for those observations defined by
the presence of low-frequency QPOs (0.1-20 Hz) and an absence of
``band-limited'' power continua: (1) The 9 time intervals with the highest 7-35
keV count rates yielded an average PDS with a QPO at $166 \pm 5$ Hz. ($4.1
\sigma$; 3--35 keV); and (2) a second group with lower 7-35 keV count rates (26
intervals) produced an average PDS with a QPO at $242 \pm 3$ Hz ($6.0 \sigma$;
7--35 keV). The ratio of these two frequencies is $1.46 \pm 0.05$. This finding
is consistent with results obtained for three other black hole systems that
exhibit commensurate HFQPOs in a 3:2 ratio. Furthermore, the occurrence of
H1743-322's slower HFQPO at times of higher X-ray luminosity closely resembles
the behavior of XTE J1550-564 and GRO J1655-40. We discuss our results in terms
of a resonance model that invokes frequencies set by general relativity for
orbital motions near a black-hole event horizon.


title:
Chandra Observations and Models of the Mixed-Morphology Supernova
  Remnant W44: Global Trends

abstract:
  As with other mixed morphology remnants, W44's projected center is bright in
thermal X-rays. It has an obvious radio shell, but no discernable X-ray shell.
X-ray bright knots dot W44's image. The Chandra data show that the remnant's
hot, bright projected center is metal-rich and that the bright knots are
regions of comparatively elevated elemental abundances. The neon abundance is
elevated, suggesting that the center is rich in ejecta. Furthermore, some of
the emitting iron atoms appear to be underionized with respect to the other
ions, providing the first X-ray evidence for dust destruction in a supernova
remnant. We use the Chandra data to test the following explanations for W44's
X-ray bright center: 1.) entropy mixing from thermal conduction or bulk mixing,
2.) cloud evaporation, and 3.) a metallicity gradient, possibly due to dust
destruction and ejecta enrichment. In these tests, we assume that the remnant
has evolved beyond the adiabatic evolutionary stage, which explains the X-ray
dimness of the shell. The entropy mixed model spectrum was found to be a good
match to the Chandra spectrum. The bright knots have similar levels of
ionization as the surrounding regions, challenging the evaporating clouds
model. While both of these models are known to predict centrally bright X-ray
morphologies, their predictions fall short of the observed brightness gradient.
The resulting brightness gap can be largely filled in by emission from the
extra metals in and near the remnant's projected center. The preponderance of
evidence suggests that W44's remarkable morphology can be attributed to dust
destruction and ejecta enrichment within an entropy mixed, adiabatic phase
supernova remnant.


title: Bayesian Power Spectrum Analysis of the First-Year WMAP data

abstract:
  We present the first results from a Bayesian analysis of the WMAP first year
data using a Gibbs sampling technique. Using two independent, parallel
supercomputer codes we analyze the WMAP Q, V and W bands. The analysis results
in a full probabilistic description of the information the WMAP data set
contains about the power spectrum and the all-sky map of the cosmic microwave
background anisotropies. We present the complete probability distributions for
each C_l including any non-Gaussianities of the power spectrum likelihood.
While we find good overall agreement with the previously published WMAP
spectrum, our analysis uncovers discrepancies in the power spectrum estimates
at low l multipoles. For example we claim the best-fit Lambda-CDM model is
consistent with the C_2 inferred from our combined Q+V+W analysis with a 10%
probability of an even larger theoretical C_2. Based on our exact analysis we
can therefore attribute the "low quadrupole issue" to a statistical
fluctuation.


title: Power spectrum estimation from high-resolution maps by Gibbs sampling

abstract:
  We revisit a recently introduced power spectrum estimation technique based on
Gibbs sampling, with the goal of applying it to the high-resolution WMAP data.
In order to facilitate this analysis, a number of sophistications have to be
introduced, each of which is discussed in detail. We have implemented two
independent versions of the algorithm to cross-check the computer codes, and to
verify that a particular solution to any given problem does not affect the
scientific results. We then apply these programs to simulated data with known
properties at intermediate (N_side = 128) and high (N_side = 512) resolutions,
to study effects such as incomplete sky coverage and white vs. correlated
noise. From these simulations we also establish the Markov chain correlation
length as a function of signal-to-noise ratio, and give a few comments on the
properties of the correlation matrices involved. Parallelization issues are
also discussed, with emphasis on real-world limitations imposed by current
super-computer facilities. The scientific results from the analysis of the
first-year WMAP data are presented in a companion letter.


title: Physical Structure of Planetary Nebulae. II. NGC 7662

abstract:
  We present a study of the structure and kinematics of the triple-shell
planetary nebula NGC 7662 based on long-slit echelle spectroscopic observations
and HST archival narrow-band images. The structure of NGC 7662 main nebula
consists of a central cavity surrounded by two concentric shells. The bright
inner shell has a non-negligible thickness and the highest density in the
nebula. The outer shell is filled with nebular material whose density profile
shows a propto 1/r drop-off in the inner regions of the shell and flattens in
the outermost regions. Both the inner and the outer shells can be described as
prolate ellipsoids: the inner shell is more elongated, while the outermost
layer of the outer shell expands faster. The physical structure of NGC 7662 is
qualitatively consistent with the predictions of hydrodynamical simulations
based on the interacting-stellar-wind models for planetary nebulae with a 0.605
solar mass central star. Models with a higher AGB wind velocity are needed for
detailed comparisons.


title: Mz 3, a Multipolar Nebula in the Making

abstract:
  The nebula Mz 3 has arguably the most complex bipolar morphology, consisting
of three nested pairs of bipolar lobes and an equatorial ellipse. Its three
pairs of bipolar lobes share the same axis of symmetry, but have very different
opening angles and morphologies: the innermost pair of bipolar lobes shows
closed lobe morphology, while the other two have open lobes with cylindrical
and conical shapes, respectively. We have carried out high-dispersion
spectroscopic observations of Mz 3, and detected distinct kinematic properties
among the different morphological components. The expansion characteristics of
the two outer pairs of lobes suggest that they originated in an explosive
event, whereas the innermost pair of lobes resulted from the interaction of a
fast wind with the surrounding material. The equatorial ellipse is associated
with a fast equatorial outflow which is unique among bipolar nebulae. The
dynamical ages of the different structures in Mz 3 suggest episodic bipolar
ejections, and the distinct morphologies and kinematics among these different
structures reveal fundamental changes in the system between these episodic
ejections.


title:
High Resolution Imaging of the HeII lambda 4686 Emission Line Nebula
  Associated with the Ultraluminous X-Ray Source in Holmberg II

abstract:
  We present Hubble Space Telescope images of the He{\sc iii} region
surrounding the bright X-ray source in the dwarf irregular galaxy Holmberg II.
Using {\it Chandra}, we find a position for the X-ray source of $\alpha=$ 08h
19m 28.98s, $\delta=$ +70\arcdeg 42\arcmin 19.\arcsec3 (J2000) with an
uncertainty of 0.6$''$. We identify a bright, point-like optical counterpart
centered in the nebula with the X-ray source. The optical magnitude and color
of the counterpart are consistent with a star with spectral type between O4V
and B3 Ib at a distance of 3.05 Mpc or reprocessed emission from an X-ray
illuminated accretion disk. The nebular He{\sc ii} luminosity is $2.7 \times
10^{36} \rm erg s^{-1}$. The morphology of the He{\sc ii}, H$\beta$, and [O{\sc
i}] emission are consistent with being due to X-ray photoionization and are
inconsistent with narrow beaming of the X-ray emission. A spectral model
consisting of a multicolor disk blackbody with inverse-Compton emission from a
hot corona gives a good fit to X-ray spectra obtained with XMM-Newton. Using
the fitted X-ray spectrum, we calculate the relation between the He{\sc ii} and
X-ray luminosity and find that the He{\sc ii} flux implies a lower bound on the
X-ray luminosity in the range 4 to $6 \times 10^{39} \rm erg s^{-1}$ if the
extrapolation of the X-ray spectrum between 54 eV and 300 eV is accurate. A
compact object mass of at least 25 to $40 M_{\odot}$ would be required to avoid
violating the Eddington limit.


title:
Weighting the Clusters of Galaxies with Weak Gravitational Lensing: The
  problem of the mass-sheet degeneracy

abstract:
  Weak gravitational lensing is considered to be one of the most powerful tools
to study the mass and the mass distribution of galaxy clusters. However, weak
lensing mass reconstructions are plagued by the so-called mass-sheet
degeneracy--the surface mass density \kappa of the cluster can be determined
only up to a degeneracy transformation \kappa \to \kappa' = \lambda \kappa + (1
-\lambda), where \lambda is an arbitrary constant. This transformation
fundamentally limits the accuracy of cluster mass determinations if no further
assumptions are made. We discuss here a possibility to break the mass-sheet
degeneracy in weak lensing mass maps using distortion and redshift information
of background galaxies. Compared to other techniques proposed in the past, it
does not rely on any assumptions on cluster potential and does not make use of
weakly constrained information (such as the source number counts, used in the
magnification effect).Our simulations show that we are effectively able to
break the mass-sheet degeneracy for supercritical lenses and that for
undercritical lenses the mass-sheet degeneracy is very difficult to be broken,
even under idealised conditions.


title:
The Low- and Intermediate-Mass Stellar Population in the Small
  Magellanic Cloud: The Central Stars of Planetary Nebulae

abstract:
  We present a study on the central stars (CSs) of Planetary Nebulae (PNe)
observed in the Small Magellanic Cloud (SMC) with the Space Telescope Imaging
Spectrograph instrument on-board the HST. The stellar magnitudes have been
measured using broad-band photometry, and Zanstra analysis of the nebulae
provided the stellar temperatures. From the location of the CSs on the HR
diagram, and by comparing the observed CSs with current models of stellar
evolution, we infer the CSs masses. We examine closely the possibility of light
contamination in the bandpass from an unrecognized stellar companion, and we
establish strong constraints on the existence and nature of any binary
companion. We find an average mass of 0.63 Msun, which is similar to the mass
obtained for a sample of CSs in the LMC (0.65 Msun). However, the SMC and LMC
CS mass distributions differ slightly, the SMC sample lacking an
intermediate-mass stellar population (0.65 to 0.75 Msun). We discuss the
significance and possible reasons for the difference between the two mass
distributions. In particular, we consider the differences in the star formation
history between the clouds and the mass-loss rate dependence on metallicity.


title:
Volume Filling Factors of the ISM Phases in Star Forming Galaxies - I.
  The Role of the Disk-Halo Interaction

abstract:
  The role of matter circulation between the disk and halo in establishing the
volume filling factors of the different ISM phases in the Galactic disk is
investigated, using a modified version of the three-dimensional
supernova-driven ISM model of Avillez (2000). We carried out adaptive mesh
refinement simulations of the ISM with five supernova rates (in units of the
Galactic value), $\sigma/\sigma_{Gal}=1$, 2, 4, 8 and 16 (corresponding to
starburst conditions) using three finer level resolutions of 2.5, 1.25 and
0.625 pc, allowing us to understand how resolution would affect the volumes of
gas phases in pressure equilibrium. We find that the volume filling factors of
the different ISM phases depend sensitively on the existence of a duty cycle
between the disk and halo acting as a pressure release valve for the hot (T>
10^5.5 K) phase in the disk.


title:
The Disk Wind in the Young Binaries and the Origin of the Cyclic
  Activity of Young Stars

abstract:
  We present results of numerical modeling of the cyclic brightness modulation
in the young binary systems with the eccentric orbits and low-mass secondary
components. Brightness variations of the primary is due to the periodical
extinction variations on the line-of-sight caused by the disk wind of the
secondary and a common envelope it produces. A matter distribution in the
envelope has been calculated in the ballistic approach. Calculations showed
that for the young binaries with the elliptic orbits parameters of the
photometric minima (their depth, duration and the shape of light curves) depend
not only on the disk wind parameters and an inclination of the binary orbit to
the line-of-sight but also on the longitude of the periastron. A modulation of
the scattered radiation of the common envelope with a phase of the orbital
period has been investigated in the single scattering approach. It is shown
that an amplitude of the modulation is maximal when the system is seen edge-on
and has also a non-zero value in the binaries observed pole-on. Possible
applications of the theory to the young stellar objects are discussed. In
particular, an attention is payed to a resemblance of the light curves in some
models with light curves of the objects suspected as candidates to FUORs.


title: A Possible Brown Dwarf Companion to the White Dwarf GD1400

abstract:
  An unresolved, likely L dwarf companion to the DA white dwarf GD1400 is
reported. This would be only the second such system known, discovered 17 years
after the prototype L dwarf, GD165B, was determined to be a companion to a
white dwarf. Photometric observations and model predicted stellar parameters of
the well studied white dwarf primary indicate that GD1400B has $J-K\ga2.0$ and
$M_K=12.13$ mag. If correct, this would place GD1400B at spectral type L6, and
it would be the lowest luminosity unevolved companion known to a white dwarf,
and thus a definite brown dwarf. However, a low resolution Keck NIRSPEC
$2.1-2.4\mu$m spectrum may not be consistent with known L dwarfs. Uncertainties
in classification remain until the binary is resolved or a trigonometric
parallax is measured.


title:
The Thermal Regulation of Gravitational Instabilities in Protoplanetary
  Disks II. Extended Simulations with Varied Cooling Rates

abstract:
  In order to investigate mass transport and planet formation by gravitational
instabilities (GIs), we have extended our 3-D hydrodynamic simulations of
protoplanetary disks from a previous paper. Our goal is to determine the
asymptotic behavior of GIs and how it is affected by different constant cooling
times. Initially, Rdisk = 40 AU, Mdisk = 0.07 Mo, M* = 0.5 Mo, and Qmin = 1.8.
Sustained cooling, with tcool = 2 orps (outer rotation periods, 1 orp ~ 250
yrs), drives the disk to instability in ~ 4 orps. This calculation is followed
for 23.5 orps. After 12 orps, the disk settles into a quasi-steady state with
sustained nonlinear instabilities, an average Q = 1.44 over the outer disk, a
well-defined power-law Sigma(r), and a roughly steady Mdot ~ 5(-7) Mo/yr. The
transport is driven by global low-order spiral modes. We restart the
calculation at 11.2 orps with tcool = 1 and 1/4 orp. The latter case is also
run at high azimuthal resolution. We find that shorter cooling times lead to
increased Mdots, denser and thinner spiral structures, and more violent dynamic
behavior. The asymptotic total internal energy and the azimuthally averaged
Q(r) are insensitive to tcool. Fragmentation occurs only in the high-resolution
tcool = 1/4 orp case; however, none of the fragments survive for even a quarter
of an orbit. Ring-like density enhancements appear and grow near the boundary
between GI active and inactive regions. We discuss the possible implications of
these rings for gas giant planet formation.


title: The VSOP 5 GHz AGN Survey II. Data Calibration and Imaging

abstract:
  The VSOP mission is a Japanese-led project to study radio sources with
sub-milliarcsecond angular resolution using an orbiting 8-m telescope, HALCA
and global arrays of Earth-based telescopes. Approximately 25% of the observing
time has been devoted to a survey of compact AGN at 5 GHz which are stronger
than 1 Jy -- the VSOP AGN Survey. This paper, the second in a series, describes
the data calibration, source detection, self-calibration, imaging and modeling,
and gives examples illustrating the problems specific to space VLBI. The VSOP
Survey web-site which contains all results and calibrated data is described.


title:
The Effect of Rotational Gravity Darkening on Magnetically Torqued Be
  Star Disks

abstract:
  In the magnetically torqued disk (MTD) model for hot star disks, as proposed
and formulated by \citet{cassi02}, stellar wind mass loss was taken to be
uniform over the stellar surface. Here account is taken of the fact that as
stellar spin rate S_o (=\sqrt {\Omega_o^2 R^3/GM}) is increased, and the
stellar equator is gravity darkened, the equatorial mass flux and terminal
speed are reduced, compared to the poles, for a given total \mdot. As a result,
the distribution of equatorial disk density, determined by the impact of north
and southbound flows, is shifted further out from the star. This results, for
high S_o (\gtrsim 0.5), in a fall in the disk mass and emission measure, and
hence in the observed emission line EW, scattering polarization, and IR
emission. Consequently, contrary to expectations, critical rotation S_o \to 1
is not the optimum for creation of hot star disks which, in terms of EM for
example, is found to occur in a broad peak around S_o\approx 0.5-0.6 depending
slightly on the wind velocity law.
  The relationship of this analytic quasi-steady parametric MTD model to other
work on magnetically guided winds is discussed. In particular the failures of
the MTD model for Be-star disks alleged by \citet{owo03} are shown to revolve
largely around open observational tests, rather in the basic MTD physics, and
around their use of insufficiently strong fields.


title: Continuous Limit of Multiple Lens Effect and the Optical Scalar Equation

abstract:
  We study the continuous limit of the multiple gravitational lensing theory
based on the thin lens approximation. Under the approximation, we define a new,
light-path dependent angular diameter distance $\tilde{d}$ and show that it
satisfies the optical scalar equation. The distance provides relations between
quantities used in the gravitational lensing theory (the convergence-, the
shear- and the twist-term) and those used in the scalar optics theory (the
rates of expansion, shear and rotation).


title:
The VSOP 5 GHz AGN Survey: III. Imaging Results for the First 102
  Sources

abstract:
  The VSOP mission is a Japanese-led project to study radio sources with
sub-milliarcsec resolution using an orbiting 8 m telescope, HALCA, along with
global arrays of Earth-based telescopes. Approximately 25% of the observing
time is devoted to a survey of compact AGN which are stronger than 1 Jy at 5
GHz-the VSOP AGN Survey. This paper, the third in the series, presents the
results from the analysis of the first 102 Survey sources. We present high
resolution images and plots of visibility amplitude versus projected baseline
length. In addition, model-fit parameters to the primary radio components are
listed, and from these the angular size and brightness temperature for the
radio cores are calculated. For those sources for which we were able to
determine the source frame core brightness temperature, a significant fraction
(53 out of 98) have a source frame core brightness temperature in excess of
10^12 K. The maximum source frame core brightness temperature we observed was
1.2 X 10^13 K. Explaining a brightness temperature this high requires an
extreme amount of relativistic Doppler beaming. Since the maximum brightness
temperature one is able to determine using only ground-based arrays is of the
order of 10^12 K, our results confirm the necessity of using space VLBI to
explore the extremely high brightness temperature regime.


title: On the Nature of Feedback Heating in Cooling Flow Clusters

abstract:
  We study the feedback between heating and cooling of the intra-cluster medium
(ICM) in cooling flow (CF) galaxies and clusters. We adopt the popular view
that the heating is due to an active galactic nucleus (AGN), i.e. a central
black hole accreting mass and launching jets and/or winds. We propose that the
feedback occurs with the entire cool inner region (r <~ 5-30 kpc), where the
non-linear over-dense blobs of gas with a density contrast >~2 cool fast and
are removed from the ICM before experiencing the next major AGN heating event.
We term this scenario "cold-feedback". Some of these blobs cool and sink toward
the central black hole, while others might form stars and cold molecular
clouds. We derive the conditions under which the dense blobs formed by
perturbations might cool to low temperatures (T <~ 10^4 K), and feed the black
hole. The main conditions are found to be: (1) An over-dense blob must be
prevented from reaching an equilibrium position in the ICM: therefore it has to
cool fast, and the density profile of the ambient gas should be shallow; (2)
Non-linear perturbations are required: they might have chiefly formed by
previous AGN activity; (3) The cooling time of these non-linear perturbations
should be short relative to few times the typical interval between successive
AGN outbursts. (4) The blobs should be magnetically disconnected from their
surroundings, in order not to be evaporated by thermal conduction.


title: Stellar complexes in M33

abstract:
  A method for identification of stellar complexes in M33 is applied. Several
OB associations form a stellar complex with mean size of 0.3 - 1 kpc. We apply
a correlation technique to compare different stellar populations in M33. Our
results confirm the existence of a strong correlation between OB stars, HII
regions and WR stars, which trace the regions of massive star formation. There
is a good correlation between red supergiants (RSGs) and WR stars in the spiral
arms of M33. This can be expected since the progenitors of WR stars are massive
OB stars or RSGs with masses greater than 20 M_sun. The massive RSGs and WR
stars probably originate from nearby sites of star formation. We consider this
fact as a ground for identification of stellar complexes in M33. The presented
method for identification of stellar complexes can be applied to other nearby
galaxies.


title: Muon Track Reconstruction and Data Selection Techniques in AMANDA

abstract:
  The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy
neutrino telescope operating at the geographic South Pole. It is a lattice of
photo-multiplier tubes buried deep in the polar ice between 1500m and 2000m.
The primary goal of this detector is to discover astrophysical sources of high
energy neutrinos. A high-energy muon neutrino coming through the earth from the
Northern Hemisphere can be identified by the secondary muon moving upward
through the detector. The muon tracks are reconstructed with a maximum
likelihood method. It models the arrival times and amplitudes of Cherenkov
photons registered by the photo-multipliers. This paper describes the different
methods of reconstruction, which have been successfully implemented within
AMANDA. Strategies for optimizing the reconstruction performance and rejecting
background are presented. For a typical analysis procedure the direction of
tracks are reconstructed with about 2 degree accuracy.


title:
Resolving the large scale spectral variability of the luminous Seyfert 1
  galaxy 1H 0419-577: Evidence for a new emission component and absorption by
  cold dense matter

abstract:
  An XMM-Newton observation of the luminous Seyfert 1 galaxy 1H 0419-577 in
September 2002, when the source was in an extreme low-flux state, found a very
hard X-ray spectrum at 1-10 keV with a strong soft excess below ~1 keV.
Comparison with an earlier XMM-Newton observation when 1H 0419-577 was `X-ray
bright' indicated the dominant spectral variability was due to a steep power
law or cool Comptonised thermal emission. Four further XMM-Newton observations,
with 1H 0419-577 in intermediate flux states, now support that conclusion,
while we also find the variable emission component in intermediate state
difference spectra to be strongly modified by absorption in low ionisation
matter. The variable `soft excess' then appears to be an artefact of absorption
of the underlying continuum while the `core' soft emission can be attributed to
recombination in an extended region of more highly ionised gas. We note the
wider implications of finding substantial cold dense matter overlying (or
embedded in) the X-ray continuum source in a luminous Seyfert 1 galaxy.


title: Analysis of RGU Photometry in Selected Area 51

abstract:
  A low-latitude anticenter field (l=189, b=+21) is investigated by using the
full calibration tools of RGU photometry. The observed RGU data are reduced to
the standard system and the separation of dwarfs and evolved stars is carried
out by an empirical method. Stars are categorized into three metallicity
classes, i.e. -0.25<[M/H]<=+0.50, -1.00<[M/H]<=-0.25, and [M/H]<=-1.00$ dex,
and their absolute magnitudes are determined by the corresponding
colour-magnitude diagrams. The unusually large scattering in the two-colour
diagrams is reduced by excluding 153 extra-galactic objects, identifying them
compared with the charts of Basel Astronomical Institute and University of
Minnesota, and by the criterion and algorithm of Gaidos et al. (1993). The
local logarithmic space density for giants, D(0)=6.75, lies within the local
densities of Gliese (1969) and Gliese & Jahreiss (1992). The local luminosity
function for the absolute magnitude interval 3<M(G)<=7 agrees with Hipparcos'
better than Gliese's, whereas there is a considerable excess for the interval 7
< M(G) <= 8 relative to both luminosity functions. This discrepancy may be due
to many reasons, i.e. cumulative catalogue errors, binarity etc.


title:
Late Universe expansion dominated by domain walls and dissipative dark
  matter

abstract:
  In this paper we show that a universe dominated by two components, namely
domain walls and dissipative dark matter such that the former slowly decays
into the latter may drive power law cosmological acceleration consistent with
the high redshift supernovae data, while the ratio between the energy densities
of both components remains fixed at late times thus solving the coincidence
problem of present acceleration. Likewise, we estimate the aforesaid ratio at
early times.


title: Future Universe With w < -1 Without Big Smash

abstract:
  It is demonstrated that if cosmic dark energy behaves like a fluid with
equation of state $p = {\rm w} \rho (p$ and $\rho$ being pressure and energy
density respectively) as well as generalized Chaplygin gas simultaneously, Big
Rip or Big smash problem does not arise even for equation of state parameter
${\rm w} < -1$.Unlike other phantom models, here, scale factor for the future
universe is found regular for all time.


title: Nuclear Activity and the Dynamics of Elliptical Galaxies

abstract:
  This paper looks for any correlation between the internal dynamics of
elliptical galaxies and the relatively mild nuclear activity found in many such
systems. We show that there is such a relation in the sense that the active
ellipticals tend to be significantly less rotationally supported than their
inactive cousins. The correlation can partly be related to the galaxies'
luminosities: the brightest galaxies tend to be more active and less
rotationally supported. However, even at lower luminosities the active and
inactive galaxies seem to have systematically different dynamics. This
variation suggests that there are significant large-scale structural
differences between active and inactive elliptical galaxies, and hence that the
existence of both types of system cannot just be the result of random sporadic
nuclear activity.


title: The Cygnus X region - a multiwavelength view

abstract:
  The Cygnus X region is one of the most nearby massive star forming regions
within our Galaxy, recognised by prominent emission throughout the entire
electromagnetic spectrum, from radio to gamma-ray waves. This paper reviews our
current knowledge about this region by describing its multi-wavelength
characteristics. Particular emphasis will be given to the central stellar
cluster Cyg OB2 that dominates the energetics and kinematics in the area. The
cluster is also believed to be an active site of nucleosynthesis, as traced by
the observation of the 1809 keV gamma-ray line, attributed to radioactive decay
of 26Al. New observations obtained by the SPI telescope onboard the INTEGRAL
gamma-ray observatory will be presented that corroborate this hypothesis, and
that for the first time allow to measure the kinematics of the gas in the hot
Cygnus X superbubble.


title: Supernova 1993J: a veiled pulsar in a binary system?

abstract:
  The recent report of a binary companion to the progenitor of supernova 1993J
may provide important clues for identifying the nature of the nascent compact
object. Given the estimates of the progenitor mass, the potential power source
is probably a pulsar rather than an accreting black hole. If there is a pulsar,
one would expect the rotational luminosity to be stored and reprocessed by the
supernova remnant, but no pulsar nebula has yet been seen. The lack of
detection of an X-ray synchrotron nebula should be taken as strong evidence
against the presence of a bright pulsar. This is because absorption by the
surrounding supernova gas should be negligible for the light of the companion
star to have been detected. A model is developed here for the luminosity of the
pulsar nebula in SN 1993J, which is then used to predict the spin-down power of
the putative pulsar. If one exists, it can be providing no more than about 6 x
10^{39} erg/s. With an initial rotation period of 10-30 ms, as extrapolated
from young galactic pulsars, the nascent neutron star can have either a weak
magnetic field, B < 10^{11} G, or one so strong, B > 10^{15} G, that its spin
was rapidly slowed down. The companion star, if bound to the neutron star,
should provide ample targets for the pulsar wind to interact and produce
high-energy gamma-rays. The expected non-pulsed, GeV signal is calculated; it
could be detected by current and future experiments provided that the pulsar
wind velocity is similar to that of the Crab Nebula.


title: On the destruction of star-forming clouds

abstract:
  Type II supernovae (SNe), probably the most important contributors to stellar
feedback in galaxy formation, explode within the very dense star-forming
clouds, where the injected energy is most easily radiated away. The efficiency
of type II SNe in injecting energy into the interstellar medium (ISM) and in
re-heating a fraction of the original star-forming cloud is estimated with the
aid of a two-phase model for the ISM of the cloud. We argue that when SNe
explode the star-forming cloud has already been partially destroyed by ionizing
light and winds from massive stars. SN remnants (SNRs) will first cause the
collapse of most of the cloud gas into cold fragments, until the diffuse hot
phase has a low enough density to make further radiative losses negligible.
This is completed in ~3 Myr, with a modest energy loss of ~5 per cent of the
total budget. We compute that a fraction ranging from 5 to 30 per cent of the
cloud is reheated to a high temperature (from 10^5 to 10^7 K); these numbers
are very uncertain, due to the very complicated nature of the problem, and to
the uncertain role of thermal evaporation. Small star-forming clouds, less
massive than ~10^4 Msun, will be destroyed by a single SN. In all cases, a high
fraction of the energy from type II SNe (~80 per cent for large clouds, smaller
but still significant for small clouds) will be available for heating the ISM.


title: Blind component separation in wavelet space. Application to CMB analysis

abstract:
  It is a recurrent issue in astronomical data analysis that observations are
unevenly sampled or incomplete maps with missing patches or intentionaly masked
parts. In addition, many astrophysical emissions are non stationary processes
over the sky. Hence spectral estimation using standard Fourier transforms is no
longer reliable. Spectral matching ICA (SMICA) is a source separation method
based on covariance matching in Fourier space which is successfully used for
the separation of diffuse astrophysical emissions in Cosmic Microwave
Background observations. We show here that wavelets, which are standard tools
in processing non stationary data, can profitably be used to extend SMICA.
Among possible applications, it is shown that gaps in data are dealt with more
conveniently and with better results using this extension, wSMICA, in place of
the original SMICA. The performances of these two methods are compared on
simulated CMB data sets, demonstrating the advantageous use of wavelets.


title:
Far-Ultraviolet Surveys of Globular Clusters: Hunting for the Products
  of Stellar Collisions and Near Misses

abstract:
  Globular clusters are gravitationally bound stellar systems containing on the
order of 100,000 stars. Due to the high stellar densities in the cores of these
clusters, close encounters and even physical collisions between stars are
inevitable. These dynamical interactions can produce exotic types of single and
binary stars that are extremely rare in the galactic field, but which may be
important to the dynamical evolution of their host clusters. A common feature
of these dynamically-formed stellar populations is that many of their members
are relatively hot, and thus bright in the far-ultraviolet (FUV) waveband. In
this short review, I describe how space-based FUV observations are being used
to find and study these populations.


title:
Image reconstruction technique and optical monitoring of the
  QSO2237+0305 from Maidanak Observatory in 2002 -- 2003

abstract:
  We have observed the gravitational lens system Q2237+0305 from the Maidanak
Observatory over the period from August 2002 to November 2003. Here we report
the results of our observations. We implemented a two-stage technique that has
been developed specifically for the purpose of gravitational lens image
reconstruction. The technique is based on the Tikhonov regularization approach
and allows one to obtain astrometric and photometric characteristics of the
gravitational lens system. Light curves with 78 data points for the four quasar
components are obtained. Slow brightness variations over the observational
period are found in all components. Images A, C, D have a tendency to decrease
in brightness. Image B does not vary more than 0.05mag. The observations did
not reveal evidence for large variations in brightness of the components due to
microlensing effects. To provide an overall picture of the photometry
behaviour, our data are combined with the Maidanak observations published for
1995 -- 2000.


title: Scaling Laws in Magnetohydrodynamic Turbulence

abstract:
  We analyze the decay laws of the kinetic and magnetic energies and the
evolution of correlation lengths in freely decaying incompressible
magnetohydrodynamic (MHD) turbulence.
  Scale invariance of MHD equations assures that, in the case of constant
dissipation parameters ({\it i.e.} kinematic viscosity and resistivity) and
null magnetic helicity, the kinetic and magnetic energies decay in time as $E
\sim t^{-1}$, and the correlation lengths evolve as $\xi \sim t^{1/2}$.
  In the helical case, assuming that the magnetic field evolve towards a
force-free state, we show that (in the limit of large magnetic Reynolds number)
the magnetic helicity remains constant, the kinetic and magnetic energies decay
as $E_v \sim t^{-1}$ and $E_B \sim t^{-1/2}$ respectively, while both the
kinetic and magnetic correlation lengths grow as $\xi \sim t^{1/2}$.


title:
The Optical Gravitational Lensing Experiment. Small Amplitude Variable
  Red Giants in the Magellanic Clouds

abstract:
  We present analysis of the large sample of variable red giants from the Large
and Small Magellanic Clouds detected during the second phase of the Optical
Gravitational Lensing Experiment (OGLE-II) and supplemented with OGLE-III
photometry. Comparing pulsation properties of detected objects we find that
they constitute two groups with clearly distinct features. In this paper we
analyze in detail small amplitude variable red giants (about 15400 and 3000
objects in the LMC and SMC, respectively). The vast majority of these objects
are multi-periodic. At least 30% of them exhibit two modes closely spaced in
the power spectrum, what likely indicates non-radial oscillations. About 50%
exhibit additional so called Long Secondary Period.
  To distinguish between AGB and RGB red giants we compare PL diagrams of
multi-periodic red giants located above and below the tip of the Red Giant
Branch (TRGB). The giants above the TRGB form four parallel ridges in the PL
diagram. Among much more numerous sample of giants below the TRGB we find
objects located on the low luminosity extensions of these ridges, but most of
the stars are located on the ridges slightly shifted in logP. We interpret the
former as the second ascent AGB red giants and the latter as the first ascent
RGB objects. Thus, we empirically show that the pulsating red giants fainter
than the TRGB are a mixture of RGB and AGB giants.
  Finally, we compare the Petersen diagrams of the LMC, SMC and Galactic bulge
variable red giants and find that they are basically identical indicating that
the variable red giants in all these different stellar environments share
similar pulsation properties.


title: Cosmological simulations of the intracluster medium

abstract:
  We investigate the properties of the intracluster medium (ICM) that forms
within N-body/hydrodynamical simulations of galaxy clusters in a \LambdaCDM
cosmology. When radiative cooling and a simple model for galactic feedback are
included, our clusters have X-ray luminosities and temperatures in good
agreement with observed systems, demonstrating the required excess entropy in
their cores. More generally, cooling and feedback increases the entropy of the
ICM everywhere, albeit without significantly affecting the slope of the profile
(S prop. to r) at large radii. The temperature of the ICM is only modestly
increased by these processes, with projected temperature profiles being in
reasonable agreement with the observations. Star/galaxy formation is still too
efficient in our simulations, however, and so our gas mass fractions are around
60 per cent of the observed value at r_{2500}. Finally, we examine the
reliability of using the hydrostatic equilibrium equation to estimate cluster
masses and find that it underpredicts the true mass of our clusters by up to 20
per cent, due to incomplete thermalisation of the gas. Feedback reduces this
discrepancy, however, with estimates being accurate to within 10 per cent out
to r_{500}.


title: Single field consistency relation for the 3-point function

abstract:
  We point out the existence of a consistency relation involving the 3-point
function of scalar perturbations which is valid in any inflationary model,
independently of the inflaton Lagrangian under the assumption that the inflaton
is the only dynamical field. The 3-point function in the limit in which one of
the momenta is much smaller than the other two is fixed in terms of the power
spectrum and its tilt. This relation, although very hard to verify
experimentally, could be easily proved wrong by forecoming data, thus ruling
out any scenario with a single dynamical field in a model independent way.


title: Helioseismological Implications of Recent Solar Abundance Determinations

abstract:
  We show that standard solar models are in good agreement with the
helioseismologically determined sound speed and density as a function of solar
radius, the depth of the convective zone, and the surface helium abundance, as
long as those models do not incorporate the most recent heavy element abundance
determinations. However, sophisticated new analyses of the solar atmosphere
infer lower abundances of the lighter metals (like C, N, O, Ne, and Ar) than
the previously widely used surface abundances. We show that solar models that
include the lower heavy element abundances disagree with the solar profiles of
sound speed and density as well as the depth of the convective zone and the
helium abundance. The disagreements for models with the new abundances range
from factors of several to many times the quoted uncertainties in the
helioseismological measurements. The disagreements are at temperatures below
what is required for solar interior fusion reactions and therefore do not
significantly affect solar neutrino emission. If errors in thecalculated OPAL
opacities are solely responsible for the disagreements, then the corrections in
the opacity must extend from 2 times 10^6 K (R = 0.7R_Sun)to 5 times 10^6 K (R
= 0.4 R_Sun), with opacity increases of order 10%.


title: Distributions of Galaxy Spectral Types in the Sloan Digital Sky Survey

abstract:
  We perform an objective classification of 170,000 galaxy spectra in the Sloan
Digital Sky Survey (SDSS) using the Karhunen-Lo\`eve (KL) transform. With about
one-sixth of the total set of galaxy spectra which will be obtained by the
survey, we are able to carry out the most extensive analysis of its kind to
date. The formalism proposed by Connolly and Szalay is adopted to correct for
gappy regions in the spectra, and to derive eigenspectra and eigencoefficients.
  From this analysis, we show that this gap-correction formalism leads to a
converging set of eigenspectra and KL-repaired spectra. Furthermore, KL
eigenspectra of galaxies are found to be convergent not only as a function of
iteration, but also as a function of the number of randomly selected galaxy
spectra used in the analysis. From these data a set of ten eigenspectra of
galaxy spectra are constructed, with rest-wavelength coverage 3450-8350
angstrom. The eigencoefficients describing these galaxies naturally place the
spectra into several classes defined by the plane formed by the first three
eigencoefficients of each spectrum. Spectral types, corresponding to different
Hubble-types and galaxies with extreme emission lines, are identified for the
170,000 spectra and are shown to be complementary to existing spectral
classifications. From a non-parametric classification technique, we find that
the population of galaxies can be divided into three classes which correspond
to early late- through to intermediate late-types galaxies. (Abridged)


title: Hot Radiative Accretion onto a Spinning Neutron Star

abstract:
  (Abridged) A new type of self-similar hot viscous radiative accretion flow
onto a rapidly spinning neutron star has recently been discovered. This ``hot
brake'' flow forms in the two-temperature zone (close to a central object), but
at a sufficiently low accretion rate and a high spin it may extend in the
radial direction beyond ~300 Schwarzchild radii into a one-temperature zone.
When the spin of the star is small enough, the flow transforms smoothly to an
advection-dominated accretion flow. All gas parameters (density, angular
velocity, temperature, luminosity, angular momentum flux) except for the radial
velocity are independent of the mass accretion rate. The radiative efficiency
may be arbitrarily large as M-dot -> 0. The gas angular momentum is transported
outward under most conditions, hence the central star is nearly always
spun-down. The flow is convectively stable. We also find that themal conduction
in the flow is strong enough to make the flow thermally stable. The very fact
that the density, temperature and angular velocity of the gas at any radius in
the hot brake flow are completely independent of the outer and inner (except
for the star spin) boundary conditions implies that the flow cannot be smoothly
matched to a general external medium as well as to general conditions on the
star surface. We demonstrate that there are two extra self-similar solutions:
one bridges the gap between the original solution and the external medium, and
another represents a boundary layer between the bulk of the flow and the star
surface, in which the gas temperature rapidly drops while the density builds
up. Finally, we briefly discuss that a hot brake flow may form around other
rapidly spinning compact objects: white dwarfs and black holes.


title:
Constraining the Structure of GRB Jets Through the log(N)-log(S)
  Distribution

abstract:
  A general formalism is developed for calculating the luminosity function and
the expected number $N$ of observed GRBs above a peak photon flux $S$ for any
GRB jet structure. This new formalism directly provides the true GRB rate
without the need for a `correction factor'. We apply it to the uniform jet (UJ)
and universal structured jet (USJ) models for the structure of GRB jets and
perform fits to the observed log(N)-log(S) distribution from the GUSBAD catalog
which contains 2204 BATSE bursts. A core angle $\theta_c$ and an outer edge at
$\theta_{max}$ are introduced for the structured jet, and a finite range of
half-opening angles $\theta_{min}\leq\theta_j\leq\theta_{max}$ is assumed for
the uniform jets. The efficiency $\epsilon_\gamma$ for producing gamma-rays,
and the energy per solid angle $\epsilon$ in the jet are allowed to vary with
$\theta_j$ (the viewing angle $\theta_{obs}$) in the UJ (USJ) model,
$\epsilon_\gamma\propto\theta^{-b}$ and $\epsilon\propto\theta^{-a}$. We find
that a single power-law luminosity function provides a good fit to the data.
Such a luminosity function arises naturally in the USJ model, while in the UJ
model it implies a power-law probability distribution for $\theta_j$,
$P(\theta_j)\propto\theta_j^{-q}$. The value of $q$ cannot be directly
determined from the fit to the observed log(N)-log(S) distribution, and an
additional assumption on the value of $a$ or $b$ is required. Alternatively, an
independent estimate of the true GRB rate would enable one to determine $a$,
$b$ and $q$. The implied values of $\theta_c$ (or $\theta_{min}$) and
$\theta_{max}$ are close to the current observational limits. The true GRB rate
for the USJ model is found to be $R_{GRB}(z=0)=0.86^{+0.14}_{-0.05} Gpc^{-3}
yr^{-1}$.


title: TeV neutrinos from core collapse supernovae and hypernovae

abstract:
  A fraction of core collapse supernovae of type Ib/c are associated with
Gamma-ray bursts, which are thought to produce highly relativistic jets.
Recently, it has been hypothesized that a larger fraction of core collapse
supernovae produce slower jets, which may contribute to the disruption and
ejection of the supernova envelope, and explain the unusually energetic
hypernovae. We explore the TeV neutrino signatures expected from such slower
jets, and calculate the expected detection rates with upcoming Gigaton
Cherenkov experiments. We conclude that individual jetted SNe may be detectable
from nearby galaxies.


title: Abundances of metal-rich H II regions in M51

abstract:
  We have obtained multi-object spectroscopy of H II regions in the spiral
galaxy M51 with the Keck I telescope and the Low Resolution Imaging
Spectrometer. For 10 objects we have detected the auroral line [N II] 5755,
while [S III] 6312 has been measured in 7 of these. This has allowed us to
measure the electron temperature of the gas and to derive O, S and N abundances
for the 10 H II regions. Contrary to the expectations from previous
photoionization models of a few H II regions in M51 and from strong-line
abundance indicators, the O/H abundance is below the solar value for most
objects, with the most metal-rich H II regions, P 203 and CCM 72, having
log(O/H) = -3.16 and log(O/H) = -3.29, respectively. The reduction of O/H by
factors up to two or three with respect to previous indirect determinations has
important consequences for the calibration of empirical abundance indicators,
such as R23, in the abundance and excitation range found in the central regions
of spiral galaxies. Based on our new abundances we revise the effective yield
for M51, now found to be almost four times lower than previous estimates, and
we discuss this result within the context of chemical evolution in galactic
disks. Features from Wolf-Rayet stars are detected in a large number of H II
regions in M51, with the C III 5696 line found preferentially in the central,
most metal-rich objects. (abridged)


title: UV star-formation rates of GRB host galaxies

abstract:
  We study a magnitude-limited sample of 10 gamma-ray burst (GRB) host galaxies
with known spectroscopic redshifts (0.43 < z < 2.04). From an analysis of the
spectral energy distributions (SEDs), based on published broad-band optical and
near-infrared photometry, we derive photometric redshifts, galaxy types, ages
of the dominant stellar populations, internal extinctions, and ultraviolet (UV)
star-formation rates (SFRs) of the host galaxies. The photometric redshifts are
quite accurate despite the heterogeneous nature of the sample: The r.m.s.
errors are sigma(z) = 0.21 and sigma(Delta z/(1+z_spec)) = 0.16 with no
significant systematic offsets. All the host galaxies have SEDs similar to
young starburst galaxies with moderate to low extinction. A comparison of
specific SFRs with those of high-redshift galaxies in the Hubble Deep Fields
shows that GRB hosts are most likely similar to the field galaxies with the
largest specific SFRs. On the other hand, GRB hosts are not significantly
younger than starburst field galaxies at similar redshifts, but are found to be
younger than a sample of all types of field galaxies.


title: Beyond the iron group: heavy metals in hot subdwarfs

abstract:
  We report the discovery of strong photospheric resonance lines of Ga III, Ge
IV, Sn IV and Pb IV in the UV spectra of more than two dozen sdB and sdOB stars
at temperatures ranging from 22000 K to 40000 K. Lines of other heavy elements
are also detected, however in these cases more atomic data are needed. Based on
these discoveries, we present a hypothesis to explain the apparent lack of
silicon in sdB stars hotter than ~32000 K. The existence of triply ionised Ge,
Sn, and Pb suggests that rather than silicon sinking deep into the photosphere,
it is removed from the star in a fractionated stellar wind. This hypothesis
provides a challenge to diffusion models of sdB stars.


title: Fuelling starbursts and AGN

abstract:
  There is considerable evidence that the circumnuclear regions of galaxies are
intimately related to their host galaxies, most directly through their bars.
There is also convincing evidence for relations between the properties of
supermassive black holes in the nuclei of galaxies and those of their host
galaxy. It is much less clear, however, how stellar (starburst) and non-stellar
(AGN) activity in the nuclear regions can be initiated and fuelled. I review
gas transport from the disk to the nuclear and circumnuclear regions of
galaxies, as well as the statistical relationships between the occurrence of
nuclear activity and mechanisms which can cause central gas concentration, in
particular bars and interactions. There are strong indications from theory and
modelling for bar-induced central gas concentration, accompanied by limited
observational evidence. Bars are related to activity, but this is only a weak
statistical effect in the case of Seyferts, whereas the relation is limited to
specific cases in starbursts. There is no observational evidence for a
statistical connection between interactions and activity in Seyferts, and some
evidence for this in starbursts, but probably limited to the extremes, e.g.,
ULIRGs. Some interesting hints at relations between rings, including nuclear
rings, and the presence of nuclear activity are emerging. It is likely that the
connection between the inflow of gaseous fuel from the disk of a galaxy on the
one hand and the activity in its nuclear region on the other is not as
straightforward as sometimes suggested, because the spatial- or time-scales
concerned may be significantly different.


title:
The VSOP 5-GHz AGN Survey: IV. The Angular Size/Brightness Temperature
  Distribution

abstract:
  The VSOP (VLBI Space Observatory Programme) mission is a Japanese-led project
to study radio sources with sub-milliarcsec angular resolution, using an
orbiting 8-m telescope on board the satellite HALCA with a global earth-based
array of telescopes. A major program is the 5 GHz VSOP Survey Program, which we
supplement here with VLBA observations to produce a complete and flux-density
limited sample. Using statistical methods of analysis of the observed
visibility amplitude versus projected (u,v) spacing, we have determined the
angular size and brightness temperature distribution of bright AGN radio cores.
On average, the cores have a diameter (full-width, half-power) of 0.20 mas
which contains about 20% of the total source emission, and (14+/-6)% of the
cores are <0.04 mas in size. About (20+/-5)% of the radio cores have a source
frame brightness temperature 10^{13}K, and (3+/-2)% have 10^{14}K. A model of
the high brightness temperature tail suggests that the radio cores have a
brightness temperatures approx 10^{12}K, and are beamed toward the observer
with an average bulk motion of v/c=0.993 +/- 0.004.


title: Long term variability of Cygnus X-1, III. Radio-X-ray correlations

abstract:
  Long time scale radio-X-ray correlations in black holes during the hard state
have been found in many sources and there seems to emerge a universal
underlying relationship which quantitatively describes this behavior. Although
it would appear only natural to detect short term emission patterns in the
X-ray and - with a certain time lag - in the radio, there has been little
evidence for this up to now. The most prominent source for radio-X-ray
correlations on short time scales (minutes) so far remains GRS 1915+105 where a
single mass ejection could be detected successively in the X-ray, IR, and radio
wavebands. We analyze a database of more than 4 years of simultaneous
radio-X-ray data for Cygnus X-1 from the Ryle Telescope and RXTE PCA/HEXTE. We
confirm the existence of a radio-X-ray correlation on long time scales,
especially at hard energies. We show that apparent correlations on short time
scales in the lightcurves of Cygnus X-1 are most likely the coincidental
outcome of white noise statistics. Interpreting this result as a breakdown of
radio-X-ray correlations on shorter time scales, this sets a limit to the speed
of the jet.


title: Cataclysmic Variables from SDSS III. The Third Year

abstract:
  This paper continues the series that identifies new cataclysmic variables
found in the Sloan Digital Sky Survey. We present 36 cataclysmic variables and
one possible symbiotic star from Sloan spectra obtained during 2002, of which
34 are new discoveries, 2 are known dwarf novae (BC UMa, KS UMa) and one is a
known CV identified from the 2dF survey. The positions, colors and spectra of
all 37 systems are presented, along with follow-up spectroscopic/photometric
observations of 10 systems. As in the past 2 years of data, the new SDSS
systems show a large variety of characteristics based on their inclination and
magnetic fields, including 3 eclipsing systems, 4 with prominent He II
emission, and 15 systems showing features of the underlying stars.


title: Theory of Parabolic Arcs in Interstellar Scintillation Spectra

abstract:
  Our theory relates the secondary spectrum, the 2D power spectrum of the radio
dynamic spectrum, to the scattered pulsar image in a thin scattering screen
geometry. Recently discovered parabolic arcs in secondary spectra are generic
features for media that scatter radiation at angles much larger than the rms
scattering angle. Each point in the secondary spectrum maps particular values
of differential arrival-time delay and fringe rate (or differential Doppler
frequency) between pairs of components in the scattered image. Arcs correspond
to a parabolic relation between these quantities through their common
dependence on the angle of arrival of scattered components. Arcs appear even
without consideration of the dispersive nature of the plasma. Arcs are more
prominent in media with negligible inner scale and with shallow wavenumber
spectra, such as the Kolmogorov spectrum, and when the scattered image is
elongated along the velocity direction. The arc phenomenon can be used,
therefore, to constrain the inner scale and the anisotropy of scattering
irregularities for directions to nearby pulsars. Arcs are truncated by finite
source size and thus provide sub micro arc sec resolution for probing emission
regions in pulsars and compact active galactic nuclei. Multiple arcs sometimes
seen signify two or more discrete scattering screens along the propagation
path, and small arclets oriented oppositely to the main arc persisting for long
durations indicate the occurrence of long-term multiple images from the
scattering screen.


title: Bihelical Magnetic Relaxation and Large Scale Magnetic Field Growth

abstract:
  A unified, three-scale system of equations accommodating nonlinear velocity
driven helical dynamos, as well as time-dependent relaxation of magnetically
dominated unihelical or bihelical systems is derived and solved herein. When
opposite magnetic helicities of equal magnitude are injected on the
intermediate and small scales, the large scale magnetic helicity grows
kinematically (independent of the magnetic Reynolds number) to equal that on
the intermediate scale. For both free and driven relaxation large scale fields
are rapidly produced. Subsequently, a dissipation-limited dynamo, driven by
growth of small scale kinetic helicity, further amplifies the large scale
field. The results are important for astrophysical coronae fed with bihelical
structures by dynamos in their host rotators. The large scale for the rotator
corresponds to the intermediate scale for the corona. That bihelical magnetic
relaxation can produce global scale fields may help to explain the formation of
astrophysical coronal holes and magnetohydrodynamic outflows.


title: Astrophysical Quark Matter

abstract:
  The quark matter may have great implications in astrophysical studies, which
could appear in the early Universe, in compact stars, and/or as cosmic rays.
After a general review of astrophysical quark matter, the density-dominated
quark matter is focused.


title:
On the alignment of classical T Tauri stars with the magnetic field in
  the Taurus-Auriga molecular cloud

abstract:
  In this paper we readdress the issue of the alignment of Classical T Tauri
stars with the magnetic field in the Taurus-Auriga molecular cloud. Previous
studies have claimed that the jet axis of active young stellar objects,
projected in the plane of the sky, is aligned preferentially along the
projected direction of the local magnetic field. We re-examine this issue in
view of the numerous high angular resolution images of circumstellar disks and
micro-jets now available. The images show that T Tauri stars as a group are
oriented randomly with respect to the local magnetic field, contrary to
previous claims. This indicates that the magnetic field may play a lesser role
in the final stages of collapse of an individual prestellar core than
previously envisioned. The current database also suggests that a subsample of
CTTS with resolved disks but without observations of bright and extended
outflows have a tendency to align perpendicularly to the magnetic field. We
discuss the possibility that this may trace a less favorable topology, e.g.,
quadrupolar, for the magnetic field in the inner disk, resulting in a weaker
collimated outflow.


title: Spectral Properties of Low Quasi-Periodic Oscillations in GRS 1915+105

abstract:
  We report on the timing analysis of RXTE observations of the Galactic
micro-quasar GRS 1915+105 performed in 2003. Out of a total of six times ~20
ks, we focus here only on the three observations during which GRS 1915+105 is
found in a steady C-state (referred to as class $\chi$) resulting in a total of
\~50 ks. During these observations, we detect low frequency quasi-periodic
oscillations with high (~14 %) rms amplitude in the 2-40 keV energy range.
Contrary to what is usually observed in GRS 1915+105, in most of our
observations the QPO frequency presents no correlation with the RXTE/PCA count
rate, nor with the RXTE/ASM count rate. We present, for the first time, high
resolution (22 spectral channels) 2-40 keV spectral fits of the energy
dependence of the QPO amplitude (``QPO spectra''). The QPO spectra are well
modeled with a cut-off power law except on one occasion where a single power
law gives a satisfactory fit (with no cut-off at least up to ~40 keV). The
cut-off energy evolves significantly from one observation to the other, from a
value of ~21.8 keV to ~30 keV in the other observations where it is detected.
We discuss the possible origin of this behavior and suggest that the compact
jet detected in the radio contributes to the hard X-ray (> 20 keV) mostly
through synchrotron emission, whereas the X-ray emitted below 20 keV would
originate through inverse Compton scattering. The dependence of the QPO
amplitude on the energy can be understood if the modulation of the X-ray flux
is contained in the Comptonized photons and not in the synchrotron ones.


title:
Nuclear star formation in the quasar PG1126-041 from adaptive optics
  assisted spectroscopy

abstract:
  We present adaptive optics assisted spectroscopy of three quasars obtained
with NACO at VLT. The high angular resolution achieved with the adaptive optics
(~0.08"), joined to the diagnostic power of near-IR spectroscopy, allow us to
investigate the properties of the innermost 100 pc of these quasars. In the
quasar with the best adaptive optics correction, PG1126-041, we spatially
resolve the Pa-alpha emission within the nuclear 100 pc. The comparison with
higher excitation lines suggests that the narrow Pa-alpha emission is due to
nuclear star formation. The inferred intensity of the nuclear star formation
(13 M(sun)/yr) may account for most of the far-IR luminosity observed in this
quasar.


title:
The Phoenix Deep Survey: the radio properties of the hard X-ray selected
  sample

abstract:
  The radio properties of hard (2-8keV) X-ray selected sources are explored by
combining a single 50ks XMM-Newton pointing with the ultra-deep and homogeneous
Phoenix radio (1.4GHz) survey (Hopkins et al. 2003). A total of 43 sources are
detected above the X-ray flux limit f_X(2-8keV)=7.7e-15cgs with 14 of them
exhibiting radio emission above ~40muJy (3sigma). The X-ray/radio matched
population lies in the borderline between radio loud and quiet AGNs and
comprises sources with both soft and hard X-ray spectral properties suggesting
both obscured and unobscured systems. The spectroscopically identified
sub-sample (total of 6 X-ray/radio matches) comprises narrow emission line AGNs
(4) with hard X-ray spectral properties and broad line sources (2) with soft
X-ray spectra. We find evidence that the fraction of X-ray/radio matches
increases from ~20% for sources with rest-frame column density N_H<1e22cm^-2 to
\~50% for more absorbed systems. Poor statistics however, limit the
significance of the above result to the ~2sigma level. Also, the X-ray/radio
matched sources have flatter coadded X-ray spectrum
(Gamma=1.78^{+0.05}_{-0.03}) compared to sources without radio emission
(Gamma=2.00^{+0.03}_{-0.04}). A possible explanation for the higher fraction of
absorbed sources with radio emission at the muJy level is the presence of
circum-nuclear starburst activity that both feeds and obscures the central
engine. For a small sub-sample of z~0.4 radio emitting AGNs with N_H>1e22cm^-2
their combined spectrum exhibits a soft X-ray component that may be associated
with star-formation activity, although other possibilities cannot be excluded.
We also find that radio emitting AGNs make up about 13-20% of the hard-band
X-ray background depending on the adopted normalisation.


title: Near-IR speckle imaging of massive young stellar objects

abstract:
  We present near-IR speckle images of 21 massive Young Stellar Objects (YSOs)
associated with outflows. The aim of this study is to search for sub-arcsecond
reflection nebulae associated with the outflow cavity. We find that 6 of the
massive YSOs show a conical nebula which can be interpreted in terms of
reflected light from the dusty walls of the outflow cavity. In all cases, the
small scale structures seen in our images are compared with outflow indicators
found in the literature. No clear correlation is found between the presence of
the reflection nebulosity and any property such as degree of embeddedness. We
also note that 3 of the sources show close companions, one of them belonging
also to the sample with conical nebula.


title: XMM-Newton EPIC Observation of the Galaxy Cluster A3667

abstract:
  The Abell cluster of galaxies A3667 was observed with XMM-Newton in 6
partially overlapping pointings. We present here the resulting X-ray surface
brightness, temperature, entropy and pressure maps and discuss the structure of
this cluster on scales from 0.1 to 30 arcminutes. Based on these observations
we refine the origin of the A3667 cold front to the displacement of the low
entropy, high metal abundance gas from the current pressure peak of the
cluster. We argue that the mushroom shape of the cold front observed here is
similar to what is seen in some numerical simulations. We also present the
first evidence for a dynamically significant angular momentum in the cold
front.


title: Multipole invariants and non-Gaussianity

abstract:
  We propose a framework for separating the information contained in the CMB
multipoles, $a_{\ell m}$, into its algebraically independent components. Thus
we cleanly separate information pertaining to the power spectrum,
non-Gaussianity and preferred axis effects. The formalism builds upon the
recently proposed multipole vectors (Copi, Huterer & Starkman 2003; Schwarz &
al 2004; Katz & Weeks 2004), and we elucidate a few features regarding these
vectors, namely their lack of statistical independence for a Gaussian random
process. In a few cases we explicitly relate our proposed invariants to
components of the $n$-point correlation function (power spectrum, bispectrum).
We find the invariants' distributions using a mixture of analytical and
numerical methods. We also evaluate them for the co-added WMAP first year map.


title: Gamma-Ray Burst Detection with INTEGRAL/SPI

abstract:
  The spectrometer SPI, one of the two main instruments of the INTEGRAL
spacecraft, has strong capabilities in the field of Gamma-Ray Burst (GRB)
detections. In its 16 deg field of view (FoV) SPI is able to trigger and to
localize GRBs with an accuracy for strong bursts better than 1 deg. The
expected GRB detection rate is about one per month.


title: Superbursts at near-Eddington mass accretion rates

abstract:
  Models for superbursts from neutron stars involving carbon shell flashes
predict that the mass accretion rate should be anywhere in excess of one tenth
of the Eddington limit. Yet, superbursts have so far only been detected in
systems for which the accretion rate is limited between 0.1 and 0.25 times that
limit. The question arises whether this is a selection effect or an intrinsic
property. Therefore, we have undertaken a systematic study of data from the
BeppoSAX Wide Field Cameras on the luminous source GX 17+2, comprising 10 Msec
of effective observing time on superbursts. GX 17+2 contains a neutron star
with regular Type-I X-ray bursts and accretes matter within a few tens of
percents of the Eddington limit. We find four hours-long flares which
reasonably match superburst characteristics. Two show a sudden rise (i.e.,
faster than 10 s), and two show a smooth decay combined with spectral
softening. The implied superburst recurrence time, carbon ignition column and
quenching time for ordinary bursts are close to the predicted values. However,
the flare decay time, fluence and the implied energy production of (2-4) x
10^17 erg/g are larger than expected from current theory.


title: High energy photon emission in the early afterglow of GRB's

abstract:
  We consider the emission within the fireball model framework of very high
energy, ~1 GeV to >1 TeV photons, on a minute time scale, during the onset of
fireball deceleration due to interaction with surrounding medium. Our time
dependent numerical model includes exact treatment of electron synchrotron
emission, inverse-Compton scattering, pair production, and evolution of
electromagnetic cascades (initiated by pair production or photo-production of
pions). We find that (i) The 1 GeV--10 GeV flux is not sensitive to model
parameters and is ~10^{-7} erg cm^-2 s^-1 for z=1 bursts, well within the
detection capabilities of GLAST; (ii) The sub-TeV flux depends on the
surrounding medium density and on the fraction of thermal energy carried by the
magnetic field, epsilon_B: It ranges from ~10^{-7} erg cm^-2 s^-1 in the case
of typical ISM density and epsilon_B <~ 10^{-4} to 10^{-10} erg cm^-2 s^-1 in
the case of a source surrounded by a wind and epsilon_B ~ 10^{-0.5}; (iii) The
sub-TeV flux is detectable by high energy gamma-ray experiments such as HESS,
MAGIC, MILAGRO, and VERITAS; (iv) Combined ~1 keV, ~1 GeV and sub-TeV
observations will allow to determine both epsilon_B and the ambient medium
density; (v) The spectra depend only weakly on the spectral index of the energy
distribution of the accelerated electrons. Pion production energy loss of high
energy protons may contribute significantly in the wind case to the luminosity
of high energy photons. However, it is difficult to distinguish in this case
between the electron and proton contributions since the spectral shape is
determined primarily by the energy dependence of the pair production optical
depth.


title:
A BeppoSAX-WFC viewpoint of new INTEGRAL sources, particularly IGR
  J17544-2619

abstract:
  Of the 21 new sources that INTEGRAL discovered up to Feb. 1, 2004, five were
detected with the BeppoSAX Wide Field Cameras at earlier times. IGR J16320-4751
appears to be a persistently active X-ray source which hints at a supergiant
Roche-lobe overflowing companion star in this proposed high-mass X-ray binary.
IGR J17091-3624 is a transient source that was detected in 1996 and 2001 with a
maximum flux of 20 mCrab (2-28 keV). It is either a Be X-ray binary or a low
mass X-ray binary transient. IGR J18483-0311 may be a high-mass X-ray binary,
because it is located in a region rich of such objects, just like IGR
J19140+098. IGR J17544-2619 appears to be a frequently active X-ray source
whose hours-long flares, of which WFC detected five, are reminiscent of the
stellar black hole source V4641 Sgr. We discuss this source in detail.


title: Quarks, Electrons, and Atoms in Closely Related Universes

abstract:
  In a model where a multiverse wavefunction explores a multitude of vacua with
different symmetries and parameters, properties of universes closely related to
ours can be understood by examining the consequences of small departures of
physical parameters from their observed values. The masses of the light
fermions that make up the stable matter of which we are made-- the up and down
quarks, and the electron-- have values in a narrow window that both allows a
variety of nuclei other than protons to exist, and at the same time allows
atoms with stable shells of electrons that are not devoured by their nuclei.
These fundamental parameters of the Standard Model are good candidates for
quantities whose values are determined through selection effects within a
multiverse, since a living world of molecules needs stable nuclei other than
just protons and neutrons. If the fermion masses are fixed by brane
condensation or compactification of extra dimensions, there may be observable
fossils of the branching event, such as a gravitational wave background.


title: New BeppoSAX-WFC results on superbursts

abstract:
  Presently seven superbursters have been identified representing 10% of the
total Galactic X-ray burster population. Four superbursters were discovered
with the Wide Field Cameras (WFCs) on BeppoSAX and three with the All-Sky
Monitor and Proportional Counter Array on RXTE. We discuss the properties of
superbursters as derived from WFC observations. There are two interesting
conclusions. First, the average recurrence time of superbursts among X-ray
bursters that are more luminous than 10% of the Eddington limit is 1.5 yr per
object. Second, superbursters systematically have higher alpha values and
shorter ordinary bursts than most bursters that have not exhibited superbursts,
indicating a higher level of stable thermonuclear helium burning. Theory
predicts hitherto undetected superbursts from the most luminous neutron stars.
We investigate the prospects for finding these in GX~17+2.


title:
Initial Scientific Results from Phase-Referenced Astrometry of
  Sub-Arcsecond Binaries

abstract:
  The Palomar Testbed Interferometer has observed several binary star systems
whose separations fall between the interferometric coherence length (a few
hundredths of an arcsecond) and the typical atmospheric seeing limit of one
arcsecond. Using phase-referencing techniques we measure the relative
separations of the systems to precisions of a few tens of micro-arcseconds. We
present the first scientific results of these observations, including the
astrometric detection of the faint third stellar component of the kappa Pegasi
system.


title:
Detecting Sunyaev-Zel'dovich clusters with PLANCK: I. Construction of
  all-sky thermal and kinetic SZ-maps

abstract:
  All-sky thermal and kinetic Sunyaev-Zel'dovich (SZ) maps are presented for
assessing how well the PLANCK-mission can find and characterise clusters of
galaxies, especially in the presence of primary anisotropies of the cosmic
microwave background (CMB) and various galactic and ecliptic foregrounds. The
maps have been constructed from numerical simulations of structure formation in
a standard LCDM cosmology and contain all clusters out to redshifts of z = 1.46
with masses exceeding 5e13 M_solar/h. By construction, the maps properly
account for the evolution of cosmic structure, the halo-halo correlation
function, the evolving mass function, halo substructure and adiabatic gas
physics. The velocities in the kinetic map correspond to the actual density
environment at the cluster positions. We characterise the SZ-cluster sample by
measuring the distribution of angular sizes, the integrated thermal and kinetic
Comptonisations, the source counts in the three relevant PLANCK-channels, and
give the angular power-spectra of the SZ-sky. While our results are broadly
consistent with simple estimates based on scaling relations and spherically
symmetric cluster models, some significant differences are seen which may
affect the number of cluster detectable by PLANCK.


title:
Detecting Sunyaev-Zel'dovich clusters with PLANCK: II. Foreground
  components and optimised filtering schemes

abstract:
  The PLANCK mission is the most sensitive all-sky CMB experiment currently
planned. The High Frequency Instrument (HFI) will be especially suited for
observing clusters of galaxies by their thermal Sunyaev-Zel'dovich (SZ) effect.
In order to assess PLANCKs SZ-capabilities in the presence of spurious signals,
a simulation is presented that combines maps of the thermal and kinetic
SZ-effects with a realisation of the cosmic microwave background (CMB), in
addition to Galactic foregrounds (synchrotron emission, free-free emission,
thermal emission from dust, CO-line radiation) as well as the sub-millimetric
emission from celestial bodies of our Solar system. Additionally, observational
issues such as the finite angular resolution and spatially non-uniform
instrumental noise of PLANCKs sky maps are taken into account, yielding a set
of all-sky flux maps, the auto-correlation and cross-correlation properties of
which are examined in detail. In the second part of the paper, filtering
schemes based on scale-adaptive and matched filtering are extended to spherical
data sets, that enable the amplification of the weak SZ-signal in the presence
of all contaminations stated above. The theory of scale-adaptive and matched
filtering in the framework of spherical maps is developed, the resulting filter
kernel shapes are discussed and their functionality is verified.


title: Distinguishing Bare Quark Stars from Neutron Stars

abstract:
  Observations to date cannot distinguish neutron stars from self-bound bare
quark stars on the basis of their gross physical properties such as their
masses and radii alone. However, their surface luminosity and spectral
characteristics can be significantly different. Unlike a normal neutron star, a
bare quark star can emit photons from its surface at super-Eddington
luminosities for an extended period of time. We present a calculation of the
photon bremsstrahlung rate from the bare quark star's surface, and indicate
improvements that are required for a complete characterization of the spectrum.
The observation of this distinctive photon spectrum would constitute an
unmistakable signature of a strange quark star and shed light on color
superconductivity at stellar densities.


title: Magnetically Driven Accretion in the Kerr Metric III: Unbound Outflows

abstract:
  We have carried out fully relativistic numerical simulations of accretion
disks in the Kerr metric. In this paper we focus on the unbound outflows that
emerge self-consistently from the accretion flow. These outflows are found in
the axial funnel region and consist of two components: a hot, fast, tenuous
outflow in the axial funnel proper, and a colder, slower, denser jet along the
funnel wall. Although a rotating black hole is not required to produce these
unbound outflows, their strength is enhanced by black hole spin. The
funnel-wall jet is excluded from the axial funnel due to elevated angular
momentum, and is also pressure-confined by a magnetized corona. The tenuous
funnel outflow accounts for a significant fraction of the energy transported to
large distances in the higher-spin simulations. We compare the outflows
observed in our simulations with those seen in other simulations.


title: The Timescale and Mode of Star Formation in Clusters

abstract:
  I discuss two questions about the origin of star clusters: How long does the
process take? What is the mode of individual star formation? I argue that
observations of Galactic star-forming regions, particularly the Orion Nebula
Cluster (ONC), indicate that cluster formation often takes several Myr, which
is many local dynamical timescales. Individual stars and binaries, including
massive stars, appear to form from the collapse of gas cores.


title:
Constraints on the dark energy equation of state from recent supernova
  data

abstract:
  Measurements suggest that our universe has a substantial dark energy
component. The most recent data on type Ia supernovae give a dark energy
density which is in good agreement with other measurements if the dark energy
is assumed to be a cosmological constant. Here we examine to what extent that
data can put constraints on a more general equation of state for the dark
energy.


title: How Do Galaxies Get Their Gas?

abstract:
  We examine the temperature history of gas accreted by forming galaxies in SPH
simulations. About half the gas shock heats to roughly the virial temperature
of the galaxy potential well before cooling, condensing, and forming stars, but
the other half radiates its acquired gravitational energy at much lower
temperatures, typically T<10^5 K, and the histogram of maximum gas temperatures
is clearly bimodal. The "cold mode" of gas accretion dominates for low mass
galaxies (M_baryon < 10^{10.3}Msun or M_halo < 10^{11.4}Msun), while the
conventional "hot mode" dominates the growth of high mass systems. Cold
accretion is often directed along filaments, allowing galaxies to efficiently
draw gas from large distances, while hot accretion is quasi-spherical. The
galaxy and halo mass dependence leads to redshift and environment dependence of
cold and hot accretion rates, with cold mode dominating at high redshift and in
low density regions today, and hot mode dominating in group and cluster
environments at low redshift. Star formation rates closely track accretion
rates, and we discuss the physics behind the observed environment and redshift
dependence of galactic scale star formation. If we allowed hot accretion to be
suppressed by conduction or AGN feedback, then the simulation predictions would
change in interesting ways, perhaps resolving conflicts with the colors of
ellipticals and the cutoff of the galaxy luminosity function. The transition
between cold and hot accretion at M_h ~ 10^{11.4}Msun is similar to that found
by Birnboim & Dekel (2003) using 1-d simulations and analytic arguments. The
corresponding baryonic mass is tantalizingly close to the scale at which
Kauffmann et al. (2003) find a marked shift in galaxy properties. We speculate
on connections between these theoretical and observational transitions.


title:
Submillimetre Constraints on Hyper-Extremely Red Objects in the Subaru
  Deep Field

abstract:
  We have mapped the submillimetre wavelength continuum emission from the
Subaru Deep Field (SDF) at 450 and 850 microns with the Submillimetre
Common-User Bolometer Array (SCUBA) detector on the James Clerk Maxwell
Telescope (JCMT). The near-IR image of the SDF is one of the deepest near-IR
images available and contains four `hyper extremely red objects' (HEROs). These
data allow us to test the connection between `extremely red objects' (EROs)
found in IR surveys and the population of bright submillimetre sources found
with SCUBA. We present a weak measurement of the average flux of the four
K-band selected HEROs of 1.15 (+/-0.46) mJy, which fails to support the
hypothesis that HEROs should be bright SCUBA sources. Our data are consistent
with the HEROs being objects with SEDs like that of Arp220 out to z~1.7,
however, the extinction in the HEROs must be about 1 magnitude greater in the
J-band than is the case for Arp220 and they would need to be 1.7 times as
luminous as Arp220. On the other hand, an evolutionary model of elliptical
galaxies at z~2-3 in a dusty starburst phase is also in agreement with the
submillimetre data, as was originally proposed for the HEROs.


title: Redshifts and Distribution of ACO Clusters of Galaxies

abstract:
  The June 2004 version of our compilation of measured redshifts for clusters
in the Abell-ACO catalogue lists redshifts for 3715 clusters/subclusters in
3033 distinct (2396 A- and 637 S-) clusters, 67% of these with N_z>=3 galaxies
measured. We provide velocity dispersions (sigma_V) for 1875 (sub)clusters
towards 1353 unique ACO clusters. The median sigma_V is 650 km/s for
A-(sub)clusters and 575 km/s for S-(sub)clusters, and sigma_V clearly increases
with both, N_z and richness, and also, somewhat surprising, with later
Bautz-Morgan type of the clusters. We show examples of supercluster properties
based on these data.


title: The Cluster M/L and the Value of Omega_m

abstract:
  From an up-to-date compilation of ACO cluster redshifts and velocity
dispersions we extract a homogeneous sample of 459 clusters with robust
velocity dispersion. Using the virial theorem to estimate cluster masses, and a
correlation between Abell galaxy counts and R-band luminosity, we find a median
M/L_R of 174 h_50 M_sun/L_sun. However, if we correct the virial masses
according to the X-ray vs. virial mass correlation, as derived from our
analysis, we obtain M/L_R ~100 h_50 M_sun/L_sun. These two values of M/L imply
a mass content of the Universe of Omega_m ~0.26 and 0.15, respectively.


title: Dust emission model of Lyman-break galaxies

abstract:
  Lyman-break galaxies (LBGs) contain a non-negligible amount of dust. Takeuchi
et al. (2003)(T03) constructed a model of the infrared spectral energy
distribution (SED) for very young galaxies by taking into account the dust size
distribution in the early stage of galaxy evolution, which can be different
from that of present-day evolved galaxies. We applied T03 model to LBGs and
constructed their expected SED. In order to examine the grain size distribution
of dust, we calculated the SEDs based on two distinct type of the distribution
models: a single-sized distribution and a power-law distribution with a slope
of $dN/da \propto a^{-3.5}$. We found that the single-sized and power-law dust
size distributions yield a very similar detectability of LBGs at the
submillimetre (submm). We also found that galaxies with a power-law dust
distribution have much less flux at mid-infrared (MIR) than the other. Then, we
applied the model to a gravitationally lensed LBG \cb (cB58), a unique probe of
the dust emission from LBGs. Our model framework well reproduced the hot dust
temperature under a natural assumption for this galaxy. We also examined the
detectability of LBGs at submm wavelengths in an eight-hour deep survey by
ALMA. By integrating over their redshifted SEDs with the observed luminosity
functions, we obtained the contribution of LBGs to the cosmic infrared
background radiation (CIRB). Although they have non-negligible amount of dust,
their contribution was found to be small, especially in the FIR $\sim 200
\mu$m. Thus, we need a strongly obscured population of galaxies which contains
a large amount of star formation, at some epoch in the history of the universe.


title: Relativistic Parker winds with variable effective polytropic index

abstract:
  Spherically symmetric hydrodynamical outflows accelerated thermally in the
vicinity of a compact object are studied by generalizing an equation of state
with a variable effective polytropic index, appropriate to describe
relativistic temperatures close to the central object and nonrelativistic ones
further away. Relativistic effects introduced by the Schwarzschild metric and
the presence of relativistic temperatures in the corona are compared with
previous results for a constant effective polytropic index and also with
results of the classical wind theory. By a parametric study of the polytropic
index and the location of the sonic transition it is found that space time
curvature and relativistic temperatures tend to increase the efficiency of
thermal driving in accelerating the outflow. Thus conversely to the classical
Parker wind, the outflow is accelerated even for polytropic indices higher than
3/2. The results of this simple but fully relativistic extension of the
polytropic equation of state may be useful in simulations of outflows from hot
coronae in black hole magnetospheres.


title: Compilation and R-matrix analysis of Big Bang nuclear reaction rates

abstract:
  We use the R-matrix theory to fit low-energy data on nuclear reactions
involved in Big Bang nucleosynthesis. A special attention is paid to the rate
uncertainties which are evaluated on statistical grounds. We provide S factors
and reaction rates in tabular and graphical formats.


title: The Dense Molecular Cores in the IRAS 21391+5802 region

abstract:
  We present a detailed kinematical study and modeling of the emission of the
molecular cores at ambient velocities surrounding IRAS 21391+5802, an
intermediate-mass protostar embedded in IC 1396N. The high-density gas emission
is found in association with three dense cores associated with the YSOs BIMA 1,
BIMA 2, and BIMA 3. The CS (5-4) and CH3OH (5-4) emission around BIMA 1 has
been modeled by considering a spatially infinitely thin ring seen edge-on by
the observer. From the model we find that CS is detected over a wider radii
range than CH3OH. A bipolar outflow is detected in the CS (2-1) line centered
near BIMA 1. This outflow could be powered by a yet undetected YSO, BIMA 1W, or
alternatively could be part of the BIMA 1 molecular outflow. The CS and CH3OH
emission associated with the intermediate-mass protostar BIMA 2 is highly
perturbed by the bipolar outflow even at cloud velocities, confirming that the
protostar is in a very active stage of mass loss. For YSO BIMA 3 the lack of
outflow and of clear evidence of infall suggests that both outflow and infall
are weaker than in BIMA 1, and that BIMA 3 is probably a more evolved object.


title: First Results from THINGS: The HI Nearby Galaxy Survey

abstract:
  We describe The HI Nearby Galaxy Survey (THINGS), the largest program ever
undertaken at the VLA to perform 21-cm HI observations of the highest quality
(~7'', <= 5 km/s resolution) of nearby galaxies. The goal of THINGS is to
investigate key characteristics related to galaxy morphology, star formation
and mass distribution across the Hubble sequence. A sample of 34 objects with
distances between 3 and 10 Mpc will be observed, covering a wide range of
evolutionary stages and properties. Data from THINGS will complement SINGS, the
Spitzer Infrared Nearby Galaxy Survey. For the THINGS sample, high-quality
observations at comparable resolution will thus be available from the X-ray
regime through to the radio part of the spectrum. THINGS data can be used to
investigate issues such as the small-scale structure of the ISM, its
three-dimensional structure, the (dark) matter distribution and processes
leading to star formation. To demonstrate the quality of the THINGS data
products, we present some prelimary HI maps here of four galaxies from the
THINGS sample.


title: Stability of SN Ia progenitors against radial oscillations

abstract:
  We analyze the possible existence of a pulsational instability excited by the
$\epsilon$-mechanism during the last few centuries of evolution of a
Chandrasekhar mass white dwarf prior to its explosion as a Type Ia supernova.
Our analysis is motivated by the temperature sensitivity of the nuclear energy
generation rate ($\sim T^{23}$) in a white dwarf whose structural adiabatic
index is near 4/3. Based upon a linear stability analysis, we find that the
fundamental mode and higher order radial modes are indeed unstable and that the
fundamental mode has the shortest growth time scale. However, the growth time
scale for such instability never becomes shorter than the evolutionary
timescale. Therefore, even though the star \emph{is} pulsationally unstable, we
do not expect these radial modes to have time to grow and to affect the
structure and explosion properties of Type Ia supernovae.


title: The hot core-ultracompact HII connection in G10.47+0.03

abstract:
  We present infrared imaging and spectroscopic data of the complex massive
star-forming region G10.47+0.03. The detection of seven mid-infrared (MIR)
sources in our field combined with a sensitive Ks/ISAAC image allows to
establish a very accurate astrometry, at the level of 0.3". Two MIR sources are
found to be coincident with two ultracompact HII regions (UCHIIs) within our
astrometric accuracy. Another MIR source lies very close to three other UCHII
regions and to the hot molecular core (HMC) in G10.47+0.03. Spectroscopy of two
of the most interesting MIR sources allows to identify the location and
spectral type of the ionizing sources. We discuss in detail the relationship
between the HMC, the UCHII regions and the nearby MIR source. The nature of the
other MIR sources is also investigated.


title: The Origin of the IMF from Core Mass Functions

abstract:
  We examine the initial mass functions (IMFs) of stars produced by different
molecular core mass functions. Simulations suggest that more massive cores
produce more stars, so we propose a model in which the average number of stars
formed in a core is equal to the initial number of Jeans masses in that core.
Small-$N$ systems decay through dynamical interactions, ejecting low-mass stars
and brown dwarfs which populate the low-mass tail of the IMF. Stars which
remain in cores are able to competitively accrete more gas and become more
massive. We deduce the forms of the core mass functions required to explain the
IMFs of Taurus, Orion, IC 348 and NGC 2547. These core mass functions fall into
two categories - one which peaks at a few $M_\odot$ to explain Taurus and NGC
2547, and one that peaks at around $0.2 M_\odot$ to explain Orion and IC 348.


title: Can dark energy evolve to the Phantom?

abstract:
  Dark energy rapidly evolving from the dustlike state in the close past to the
phantomlike state at present has been recently proposed as the best fit for the
supernovae Ia data. Assuming that a dark energy component with an arbitrary
scalar-field Lagrangian, which has a general dependence on the field itself and
its first derivatives, dominates in the flat Friedmann universe, we analyze the
possibility of a dynamical transition from the states with w>-1 to those with
w<-1 or vice versa. We have found that generally such transitions are
physically implausible because they are either realized by a discrete set of
trajectories in the phase space or are unstable with respect to the
cosmological perturbations. This conclusion is confirmed by a comparison of the
analytic results with numerical solutions obtained for simple models. Without
the assumption of the dark energy domination, this result still holds for a
certain class of dark energy Lagrangians, in particular, for Lagrangians
quadratic in field's first derivatives. The result is insensitive to topology
of the Friedmann universe as well.