title: An XMM-Newton observation of A3921: an off-axis merger

abstract:
  We present the results of a detailed analysis of the XMM-Newton observation
of the galaxy cluster Abell 3921. The X-ray morphology of the cluster is
elliptical, with the centroid offset from the brightest cluster galaxy by 17
arcsec, and with a pronounced extension toward the NW. Subtraction of a 2D beta
model fit to the main cluster emission reveals a large scale, irregular
residual structure in the direction of the extension, containing both diffuse
emission from the intra cluster medium, and extended emission from the second
and third-brightest cluster galaxies (BG2 and BG3). The greatest concentration
of galaxies in the subcluster lies at the extreme northern edge of the
residual. The cluster exhibits a remarkable temperature structure, in
particular a bar of significantly hotter gas, oriented SE-NW and stretching
from the centre of the cluster towards BG2 and BG3. Our detailed study of the
morphological and thermal structure points to an off-axis merger between a main
cluster and a less massive galaxy cluster infalling from the SE. From
comparison of the temperature map with numerical simulations, and with
independent calculations based on simple physical assumptions, we conclude that
the merging event is ~0.5 Gyr old. The cluster is thus perhaps the best X-ray
observed candidate so far of an intermediate mass ratio, moderate impact
parameter merger.


title:
On the Rotational Dynamics of Magnetically Threaded Disks around Neutron
  Stars

abstract:
  We investigate the rotational dynamics of disk accretion around a strongly
magnetized neutron star with an aligned dipole field. The magnetospheric field
is assumed to thread the disk plasma both inside and outside the corotation
radius. As a result of disk-star interaction, the magnetic torque on the disk
affects the structure of accretion flow to yield the observed spin-up or
spin-down rates for a source of given fastness, magnetic field strength, and
mass accretion rate. Within the model we obtain a prescription for the
dynamical viscosity of such magnetically modified solutions for a Keplerian
disk. We then use this prescription to find a model solution for the rotation
rate profile throughout the entire disk including the non-Keplerian inner disk.
We find that the non-Keplerian angular velocity transition region is not
necessarily narrow for a source of given spin state. The boundary layer
approximation, as in the standard magnetically threaded disk model, holds only
in the case of dynamical viscosity decreasing all the way to the innermost edge
of the disk. These results are applied to several observed disk-fed X-ray
pulsars that have exhibited quasi-periodic oscillations (QPOs). The QPO
frequencies provide a constraint on the fastness parameter and enable one to
determine uniquely the width of the angular velocity transition zone for each
source within model assumptions. We discuss the implications of these results
on the value of the critical fastness parameter for a magnetized star in spin
equilibrium. Applications of our model are also made with relevant parameters
from recent numerical simulations of quasi-stationary disk-magnetized star
interactions.


title:
The Largest Blueshifts of [O III] emission line in Two Narrow-Line
  Quasars

abstract:
  We have obtained optical intermediate resolution spectra (R = 3000) of the
narrow-line quasars DMS 0059-0055 and PG 1543+489. The [O III] emission line in
DMS 0059-0055 is blueshifted by 880 km/s relative to Hbeta. We also confirm
that the [O III] emission line in PG 1543+489 has a relative blueshift of 1150
km/s. These two narrow-line quasars show the largest [O III] blueshifts known
to date among type 1 active galactic nuclei (AGNs). The [O III] emission lines
in both objects are broad (1000 - 2000 km/s) and those in DMS 0059-0055 show
strong blue asymmetry. We interpret the large blueshift and the profile of the
[O III] lines as the result of an outflow interacting with circumnuclear gas.
Among type 1 AGNs with large blueshifted [O III], there is no correlation
between the Eddington ratios and the amount of [O III] blueshifts. Combining
our new data with published results, we confirm that the Eddington ratios of
the such AGNs are the highest among AGNs with the same black hole masses. These
facts suggest that the Eddington ratio is a necessary condition or the [O III]
blueshifts weakly depend on the Eddington ratio. Our new sample suggests that
there are possible necessary conditions to produce an outflow besides a high
Eddington ratio: large black hole mass (> 10^7 M_solar) or high mass accretion
rate (> 2 M_solar/yr) or large luminosity (lambda L_{lambda} (5100A) > 10^44.6
erg/s).


title:
Thorium-rich halo star HD221170: further evidence against the
  universality of the r-process

abstract:
  We report the abundance determination in the atmosphere of the bright halo
star HD221170. The spectra were taken with the Terskol Observatory's 2.0-m
telescope with a resolution R=45000 and signal-to-noise ratio up to 250 in the
wavelength region 3638-10275 \AA. The adopted atmospheric parameters correspond
to an effective temperature \Tef=4475 K, a surface gravity \lgg=1.0, a
microturbulent velocity \vmi=1.7 \kms, and a macroturbulent velocity \vma=4
\kms. The abundances of 43 chemical elements were determined with the method of
spectrum synthesis. The large overabundances (by 1 dex relative to iron) of
elements with Z$>38$ are shown to follow the same pattern as the solar
r-abundances. The present HD221170 analysis confirms the non-universality of
the r-process, or more exactly the observation that the astrophysical sites
hosting the r-process do not always lead to a unique relative abundance
distribution for the bulk Ba to Hg elements, the Pb-peak elements, and the
actinides.


title: A Star Catalog for the Open Cluster NGC188

abstract:
  We present new BVRI broad-band photometry for the old open cluster NGC188
based upon analysis of 299 CCD images either obtained by us, donated by
colleagues, or retrieved from public archives. We compare our results on a
star-by-star basis with data from eleven previous photometric investigations of
the cluster. We homogenize and merge the data from all the photometric studies,
and also merge membership probabilities from four previous proper-motion
studies of the cluster field. Fiducial cluster sequences in the BV (Johnson) RI
(Cousins) photometric system of Landolt (1992, AJ, 104, 340) represent the
principal result of this paper. These have been compared to reference samples
defined by (a) Landolt's standard stars, (b) the old open clusters M67 and
NGC6791, and (c) stars within 25 pc having modern photometry and precise
Hipparcos parallaxes. In a companion paper we show that our derived cluster
results agree well with the predictions of modern stellar-interior and
-evolution theory, given reasonable estimates of the cluster chemical
abundances and foreground reddening. The individual and combined datasets for
NGC188 have been made available through our web site.


title: Some Consequences of the Baryonic Dark Matter Population

abstract:
  Microlensed double-image quasars have sent a consistent message that the
baryonic dark matter consists of a population of free-roaming planet mass
objects, as summarized previously. These were previously predicted to have
formed at the time of recombination, 300,000 years after the Big Bang, whence
they collapsed on a Kelvin Helmholz time scale. Today they are glimpsed as the
cometary knots in planetary nebulae. But they probably also nucleate the
mysterious Lyman-alpha clouds and cause a reduction in the transparency of the
universe to distant quasars and supernovae.


title:
Electron-Ion Recombination Rate Coefficients and Photoionization Cross
  Sections for Astrophysically Abundant Elements VIII. Ar XIII with new
  features

abstract:
  Ar XIII is found to be unique with new features in electron-ion recombination
not seen in any other ion. The ion has been studied with the unified method
which provides a theoretically self-consistent set of atomic parameters for the
inverse processes of photoionization and total electron-ion recombination. The
unified method subsumes both the radiative recombination (RR) and dielectronic
recombination (DR) within the framework of close-coupling formulations using
the R-matrix method. A set of four DR "bumps", two in the low and two in the
high temperature regions, is found to exist in the recombination rates of Ar
XIV + e $\to$ Ar XIII. This is in contrast to two typical DR "bumps", one at
high temperature common for most ions and one at low temperature depending on
the presence of near threshold autoionizing resonances in the bound-free
process. The large scale ab initio calculations for Ar XIII employ
eigenfunction expansion of 37 core Ar XIV states from n = 2 and 3 complexes.
This enables core excitations of type $\Delta n$ = 0 and 1. Ar XIII exhibits
more extensive resonant structures and wider PEC (photoexitation-of-core)
resonances for n = 3 core states than those of n = 2 states. Hence the high
energy region of photoionization and recombination are dominated by these
structures. Total and partial photoionization cross sections of all bound
states, state-specific recombinaion rates of 561 bound states and total
recombination rate coefficients are presented.


title: A Comparison of Local SNIa with the IRAS PSCz Gravity Field

abstract:
  We compare the measured peculiar velocities of 98 local (<150/h Mpc) type Ia
supernovae with predictions derived from the PSCz survey. There is excellent
agreement between the two datasets with a best fit beta_I (=Omega_m^0.6/b_I) of
0.55+-0.06. Subsets of the supernovae dataset are further analysed and the
above result is found to be robust with respect to culls by distance,
host-galaxy extinction and to the choice of reference frame in which the
analysis is carried out. Alternative methods of determining beta_I including
density-density comparisons, dipole measurements and WMAP-based results are
also discussed. We conclude that most recent determinations are consistent with
a value of beta_I=0.5.


title: Neutron-Capture Element Abundances in Halo Stars

abstract:
  We present new abundance observations of neutron-capture elements in Galactic
stars. These include new Hubble Space Telescope (HST) detections of the
elements Ge, Zr and Pt in a group of 11 halo stars. Correlations between these
elements and Eu (obtained with ground-based observations), and with respect to
metallicity, are also presented.


title: Turbulent Control of the Star Formation Efficiency

abstract:
  Supersonic turbulence plays a dual role in molecular clouds: On one hand, it
contributes to the global support of the clouds, while on the other it promotes
the formation of small-scale density fluctuations, identifiable with clumps and
cores. Within these, the local Jeans length $\Ljc$ is reduced, and collapse
ensues if $\Ljc$ becomes smaller than the clump size and the magnetic support
is insufficient (i.e., the core is ``magnetically supercritical''); otherwise,
the clumps do not collapse and are expected to re-expand and disperse on a few
free-fall times. This case may correspond to a fraction of the observed
starless cores. The star formation efficiency (SFE, the fraction of the cloud's
mass that ends up in collapsed objects) is smaller than unity because the mass
contained in collapsing clumps is smaller than the total cloud mass. However,
in non-magnetic numerical simulations with realistic Mach numbers and
turbulence driving scales, the SFE is still larger than observational
estimates. The presence of a magnetic field, even if magnetically
supercritical, appears to further reduce the SFE, but by reducing the
probability of core formation rather than by delaying the collapse of
individual cores, as was formerly thought. Precise quantification of these
effects as a function of global cloud parameters is still needed.


title: Radio Variability of Radio Quiet and Radio Loud Quasars

abstract:
  The majority of quasars are weak in their radio emission, with flux densities
comparable to those in the optical, and energies far lower. A small fraction,
about 10%, are hundreds to thousands of times stronger in the radio.
Conventional wisdom holds that there are two classes of quasars, the radio
quiets and radio louds, with a deficit of sources having intermediate power.
Are there really two separate populations, and if so, is the physics of the
radio emission fundamentally different between them? This paper addresses the
second question, through a study of radio variability across the full range of
radio power, from quiet to loud. The basic findings are that the root mean
square amplitude of variability is independent of radio luminosity or
radio-to-optical flux density ratio, and that fractionally large variations can
occur on timescales of months or less in both radio quiet and radio loud
quasars. Combining this with similarities in other indicators, such as radio
spectral index and the presence of VLBI-scale components, leads to the
suggestion that the physics of radio emission in the inner regions of all
quasars is essentially the same, involving a compact, partially opaque core
together with a beamed jet.


title: Mira science with interferometry: a review

abstract:
  Model-predicted and observed properties of the brightness distribution on
M-type Mira disks are discussed. Fundamental issues of limb-darkening and
diameter definition, of assigning observational data to diameter-type
quantities and of interpreting such quantities in terms of model diameters are
outlined. The influence of model properties upon interpretation of measured
data is clarified. The dependence of the centre-to-limb variation (CLV) of
intensity on wavelength, on stellar parameters and on variablity phase and
cycle may be used for analyzing the geometrical and physical structure of the
Mira atmosphere, for determining fundamental stellar parameters, and for
investigating the quality of models. Desirable future observations include
simultaneous observations in different spectral features at different phases
and cycles, observation of the position of the shock front and observation of
the time- and wavelength-dependence of deviations from spherical symmetry.


title:
The Nature and Excitation Mechanisms of Acoustic Oscillations in Solar
  and Stellar Coronal Loops

abstract:
  In the recent work of Nakariakov et al. (2004), it has been shown that the
time dependences of density and velocity in a flaring loop contain pronounced
quasi-harmonic oscillations associated with the 2nd harmonic of a standing slow
magnetoacoustic wave. That model used a symmetric heating function (heat
deposition was strictly at the apex). This left outstanding questions: A) is
the generation of the 2nd harmonic a consequence of the fact that the heating
function was symmetric? B) Would the generation of these oscillations occur if
we break symmetry? C) What is the spectrum of these oscillations? Is it
consistent with a 2nd spatial harmonic? The present work (and partly Tsiklauri
et al. (2004b)) attempts to answer these important outstanding questions.
Namely, we investigate the physical nature of these oscillations in greater
detail: we study their spectrum (using periodogram technique) and how heat
positioning affects the mode excitation. We found that excitation of such
oscillations is practically independent of location of the heat deposition in
the loop. Because of the change of the background temperature and density, the
phase shift between the density and velocity perturbations is not exactly a
quarter of the period, it varies along the loop and is time dependent,
especially in the case of one footpoint (asymmetric) heating. We also were able
to model successfully SUMER oscillations observed in hot coronal loops.


title: A Prototype for the PASS Permanent All Sky Survey

abstract:
  A prototype system for the Permanent All Sky Survey (PASS) project is
presented. PASS is a continuous photometric survey of the entire celestial
sphere with a high temporal resolution. Its major objectives are the detection
of all giant-planet transits (with periods up to some weeks) across stars up to
mag 10.5, and to deliver continuously photometry that is useful for the study
of any variable stars. The prototype is based on CCD cameras with short focal
length optics on a fixed mount. A small dome to house it at Teide Observatory,
Tenerife, is currently being constructed. A placement at the antarctic Dome C
is also being considered. The prototype will be used for a feasibility study of
PASS, to define the best observing strategies, and to perform a detailed
characterization of the capabilities and scope of the survey. Afterwards, a
first partial sky surveying will be started with it. That first survey may be
able to detect transiting planets during its first few hundred hours of
operation. It will also deliver a data set around which software modules
dealing with the various scientific objectives of PASS will be developed. The
PASS project is still in its early phase and teams interested in specific
scientific objectives, in providing technical expertise, or in participating
with own observations are invited to collaborate.


title: Photon mass in inflation and nearly minimal magnetogenesis

abstract:
  We argue that the dynamics of photons canonically coupled to scalars in de
Sitter inflation gets modified by a photon mass term. This might have lead to
generation of potentially observable magnetic field correlated over
cosmological scales today.


title:
CI emission in Ultra Luminous Infrared Galaxies as a molecular gas mass
  tracer

abstract:
  We present new sensitive wide-band measurements of the fine structure line
3^P_1 -> 3^P_0 (J=1-0, 492GHz) of neutral atomic carbon (CI) in the two typical
Ultra Luminous Infrared Galaxies NGC6240 and Arp220. We then use them along
with several other CI measurements in similar objects found in the literature
to estimate their global molecular gas content under the assumption of a full
CI-H_2 concomitance. We find excellent agreement between the H_2 gas mass
estimated with this method and the standard methods using 12^CO. This may
provide a new way to measure H_2 gas mass in galaxies, and one which may be
very valuable in ULIRGs since in such systems the bright 12^CO emission is
known to systematically overestimate the gas mass while their 13^CO emission is
usually very weak. At redshifts z>=1 the CI J=1-0 line shifts to much more
favorable atmospheric windows and can become a viable alternative tracer of the
H_2 gas fueling starburst events in the distant Universe.


title:
Massive star-formation rates of gamma-ray burst host galaxies: an
  unobscured view in X-rays

abstract:
  The hard X-ray (2-10keV) luminosity of a star-forming galaxy tracks its
population of high mass X-ray binaries and is essentially unobscured. It is
therefore a practically unbiased measure of star-formation in the host galaxies
of gamma-ray bursts (GRBs). Using recent and archival observations of GRBs with
the XMM-Newton and Chandra X-ray observatories, limits are placed on the
underlying X-ray emission from GRB hosts. Useful limits on the current massive
star-formation rates (SFRs), unaffected by obscuration, are obtained for the
hosts of three low redshift GRBs: GRB980425, GRB030329 and GRB031203. These
limits show that though the specific SFRs may be high (as in dwarf starburst
galaxies), none have massive obscured star-formation at the levels implied by
the sub-mm detection of some GRB hosts. It is also shown that in cases where
the faint luminosities of the late time afterglow or supernova emission are of
interest, the contribution of the host galaxy to the X-ray flux may be
significant.


title: Integral/Rxte observations of GRS 1915+105

abstract:
  We report here the first results of the spectral and timing analysis of our
simultaneous INTEGRAL/RXTE observations of GRS 1915+105. The first observation
ever performed with INTEGRAL revealed a new class of variability, where changes
of luminosity seem driven by changes in the Comptonising medium. The
spectro-temporal study of our data taken later, in the steady state, could show
the influence of the compact jet in the hard X-rays.


title: Fragment Driven Magnetic Reconnection

abstract:
  In this paper, we investigate a simple model where two, initially
unconnected, flux systems are forced to interact in response to the imposed
boundary driving by solving the non-ideal 3D MHD equations numerically. The
reconnection rate of the dynamical process is determined and compared with the
corresponding rate for the potential evolution of the magnetic field. This
shows that the dynamic reconnection rate is about a factor of two smaller than
the potential (perfect, instantaneous) rate for realistic solar driving
velocities demonstrating that this three-dimensional magnetic reconnection
process is fast.
  The energy input for a fixed advection distance is found to be independent of
the driving velocity. The Joule dissipation associated with the reconnection
process is also found to be basically dependent on the advection distance
rather than driving velocity. This implies that the timescale for the event
determines the effect the heating has on the temperature increase.
  Finally, the numerical experiments indicate that the observational structure
of the reconnection site changes dramatically depending on the phase of the
evolution of the passage of the two flux sources. In the initial phase, where
the sources become connected, the heating is confined to a compact region. For
the disconnecting phase the energy gets distributed over a larger area due to
the reconnected field line connectivity.


title: MAGIC and the Search for Signatures of Supersymmetric Dark Matter

abstract:
  The 17m Imaging Air shower Cherenkov Telescope MAGIC (Roque de los Muchachos
Observatory, La Palma, Canary Islands) has recently entered its commissioning
phase. One of the main goals of the MAGIC telescope project is to provide an
unprecedented sensitivity for the detection of gamma rays with energies as low
as 30 GeV. A dedicated search for the gamma rays expected to be produced by
WIMP annihilations is a prime object of the MAGIC physics program. We consider
annihilating supersymmetric dark matter in M 87 and discuss a possible
observation strategy. New calculations concerning the extragalactic gamma ray
and neutrino backgrounds owing to cosmological neutralino annihilation are also
briefly discussed.


title: The Selection Function of SZ Cluster Surveys

abstract:
  We study the nature of cluster selection in Sunyaev-Zel'dovich (SZ) surveys,
focusing on single frequency observations and using Monte Carlo simulations
incorporating instrumental effects, primary cosmic microwave background (CMB)
anisotropies and extragalactic point sources. Clusters are extracted from
simulated maps with an optimal, multi-scale matched filter. We introduce a
general definition for the survey selection function that provides a useful
link between an observational catalog and theoretical predictions. The
selection function defined over the observed quantities of flux and angular
size is independent of cluster physics and cosmology, and thus provides a
useful characterization of a survey. Selection expressed in terms of cluster
mass and redshift, on the other hand, depends on both cosmology and cluster
physics. We demonstrate that SZ catalogs are not simply flux limited, and
illustrate how incorrect modeling of the selection function leads to biased
estimates of cosmological parameters. The fact that SZ catalogs are not flux
limited complicates survey ``calibration'' by requiring more detailed
information on the relation between cluster observables and cluster mass.


title:
Mass loss from dwarf spheroidal galaxies: the origins of shallow dark
  matter cores and exponential surface brightness profiles

abstract:
  Dwarf spheroidal galaxies have shallow central dark matter density profiles,
low angular momentum and approximately exponential surface brightness
distributions. Through N-body simulations and analytic calculations we
investigate the extent to which these properties can be generated from
``typical'' $\Lambda$CDM galaxies, which differ in all of these properties, by
the dynamical consequences of feedback.
  We find that, for a wide range of initial conditions, one impulsive mass loss
event will naturally produce a surface brightness profile in the remaining
stellar component of a dwarf spheroidal galaxy (dSph) which is well fit over
many scale lengths by an exponential, in good qualitative agreement with
observations of Local Group dSphs. Furthermore, two impulsive mass loss phases,
punctuated by significant gas re-accretion, are found to be sufficient to
transform a central density cusp in the dark matter profile into a
near-constant density core. This may then provide the missing link between
current cosmological simulations, which predict a central cusp in the dark
matter density profile, and current observations, which find much shallower
central density profiles.
  We also look at the angular momentum history of dSphs and demonstrate that if
these galaxies have spent most of their lifetime in tidal isolation from
massive galaxies then they cannot have formed from high angular momentum gas
discs.


title: A Chandra Survey of Quasar Jets: First Results

abstract:
  We present results from Chandra X-ray imaging and spectroscopy of a
flux-limited sample of flat spectrum radio-emitting quasars with jet-like
extended structure. Twelve of twenty quasar jets are detected in 5 ks ACIS-S
exposures. The quasars without X-ray jets are not significantly different from
those in the sample with detected jets except that the extended radio emission
is generally fainter. New radio maps are combined with the X-ray images in
order to elucidate the relation between radio and X-ray emission in spatially
resolved structures. We find a variety of morphologies, including long straight
jets and bends up to 90 degrees. All X-ray jets are one-sided although the
radio images used for source selection often show lobes opposite the X-ray
jets. The FR II X-ray jets can all be interpreted as inverse Compton scattering
of cosmic microwave background photons by electrons in large-scale relativistic
jets although deeper observations are required to test this interpretation in
detail. Applying this interpretation to the jets as a population, we find that
the jets would be aligned to within 30 degrees of the line of sight generally,
assuming that the bulk Lorentz factor of the jets is 10.


title:
A multi-color and Fourier study of RR Lyrae variables in the globular
  cluster NGC 5272 (M3)

abstract:
  We have performed a detailed study of the pulsational and evolutionary
characteristics of 133 RR Lyrae stars in the globular cluster NGC5272 (M3)
using highly accurate BVI data taken on 5 separate epochs. M3 seems to contain
no less than ~32% of Blazhko stars, and the occurrence and characteristics of
the Blazhko effect have been analyzed in detail. We have identified a good
number (~ 14%) of overluminous RR Lyrae stars that are likely in a more
advanced evolutionary stage off the Zero Age Horizontal Branch (ZAHB). Physical
parameters (i.e. temperature, luminosity, mass) have been derived from (B--V)
colors and accurate color-temperature calibration, and compared with Horizontal
Branch evolutionary models and with the requirements of stellar pulsation
theory. Additional analysis by means of Fourier decomposition of the V light
curves confirms, as expected, that no metallicity spread is present in M3.
Evolution off the ZAHB does not affect [Fe/H] determinations, whereas Blazhko
stars at low amplitude phase do affect [Fe/H] distributions as they appear more
metal-rich. Absolute magnitudes derived from Fourier coefficients might provide
useful average estimates for groups of stars, if applicable, but do not give
reliable {\em individual} values. Intrinsic colors derived from Fourier
coefficients show significant discrepancies with the observed ones, hence the
resulting temperatures and temperature-related parameters are unreliable.


title: The star-forming environment of a ULX in NGC 4559: an optical study

abstract:
  We have studied the candidate optical counterparts and the stellar population
in the star-forming complex around a bright ULX in NGC4559, using HST/WFPC2,
XMM-Newton/OM, and ground-based data. We find that the ULX is located near a
small group of OB stars. The brightest point source in the Chandra error circle
is consistent with a single blue supergiant of mass ~ 20 M_sun and age ~ 10
Myr. A few other stars are resolved inside the error circle: mostly blue and
red supergiants with masses ~ 10-15 M_sun and ages ~ 20 Myr. This is consistent
with the interpretation of this ULX as a black hole (BH) accreting from a
high-mass donor star in its supergiant phase, via Roche-lobe overflow. The
observed optical colors and the blue-to-red supergiant ratio suggest a low
metal abundance: 0.2 <~ Z/Z_sun <~ 0.4 (Padua tracks), or 0.05 <~ Z/Z_sun <~
0.2 (Geneva tracks). The age of the star-forming complex is <~ 30 Myr. H-alpha
images show that this region has a ring-like appearance. We propose that it is
an expanding wave of star formation, triggered by an initial density
perturbation, in a region where the gas was only marginally stable to
gravitational collapse. A possible trigger was the collision with a satellite
dwarf galaxy, visible a few arcsec north-west of the complex, going through the
gas-rich outer disk of NGC4559. The X-ray data favour a BH more massive (M > 50
M_sun) than typical Milky Way BH candidates. The optical data favour a
``young'' BH originating in the recent episode of massive star formation;
however, they also rule out an association with young massive star clusters. We
speculate that other mechanisms may lead to the formation of relatively massive
BHs (~ 50-100 M_sun) from stellar evolution processes in low-metallicity
environments, or when star formation is triggered by galactic collisions.


title: Polarization Observations with the Cosmic Background Imager

abstract:
  Polarization observations of the cosmic microwave background with the Cosmic
Background Imager from September 2002 to May 2004 provide a significant
detection of the E-mode polarization and reveal an angular power spectrum of
polarized emission showing peaks and valleys that are shifted in phase by half
a cycle relative to those of the total intensity spectrum. This key agreement
between the phase of the observed polarization spectrum and that predicted
based on the total intensity spectrum provides support for the standard model
of cosmology, in which dark matter and dark energy are the dominant
constituents, the geometry is close to flat, and primordial density
fluctuations are predominantly adiabatic with a matter power spectrum
commensurate with inflationary cosmological models.


title: The HI Parkes Zone of Avoidance Survey: the Northern Extension

abstract:
  We present the results of the northern extension of the HI Parkes Zone of
Avoidance Survey, a blind HI survey utilizing the multibeam receiver on the
Parkes 64-m telescope. In the two regions studied here, l=36 to 52 deg. and
l=196 to 212 deg., |b|<5 deg., we have detected 77 HI galaxies, twenty of which
have been previously detected in HI. The survey has a median rms noise of 6.0
mJy/beam and is complete to a mean flux density of 22 mJy. We have searched for
multiwavelength counterparts to the 77 galaxies detected here: 19, 27, and 11
have a likely optical, 2MASS, and IRAS cataloged counterpart, respectively. A
further 16 galaxies have likely visible counterparts on the Digitized Sky
Survey. The detection of these 77 galaxies allows a closer inspection of the
large-scale structures in these regions. We see several filaments crossing the
Galactic plane, one of which appears to be the continuation of a sine-wave like
feature that can be traced across the whole southern sky. An analysis of the HI
mass function suggests that the regions studied here may be underdense. One
particularly noteworthy galaxy is HIZOA J0630+08 (l,b = 203 deg., -0.9 deg.)
with a velocity of 367 km/s. We suggest that it belongs to the nearby Orion
Group which includes a small number of dwarf galaxies. The newly detected
galaxies improve our understanding of the properties of several voids, such as
the Orion, Gemini, and Canis Major Voids.


title:
Colors, magnitudes and velocity dispersions in early-type galaxies:
  Implications for galaxy ages and metallicities

abstract:
  We present an analysis of the color-magnitude-velocity dispersion relation
for a sample of 39320 early-type galaxies within the Sloan Digital Sky Survey.
We demonstrate that the color-magnitude relation is entirely a consequence of
the fact that both the luminosities and colors of these galaxies are correlated
with stellar velocity dispersions. Previous studies of the color-magnitude
relation over a range of redshifts suggest that the luminosity of an early-type
galaxy is an indicator of its metallicity, whereas residuals in color from the
relation are indicators of the luminosity-weighted age of its stars. We show
that this, when combined with our finding that velocity dispersion plays a
crucial role, has a number of interesting implications. First, galaxies with
large velocity dispersions tend to be older (i.e., they scatter redward of the
color-magnitude relation). Similarly, galaxies with large dynamical mass
estimates also tend to be older. In addition, at fixed luminosity, galaxies
which are smaller, or have larger velocity dispersions, or are more massive,
tend to be older. Second, models in which galaxies with the largest velocity
dispersions are also the most metal poor are difficult to reconcile with our
data. However, at fixed velocity dispersion, galaxies have a range of ages and
metallicities: the older galaxies have smaller metallicities, and vice-versa.
Finally, a plot of velocity dispersion versus luminosity can be used as an age
indicator: lines of constant age run parallel to the correlation between
velocity dispersion and luminosity.


title:
A Method for Separating the Physics from the Astrophysics of
  High-Redshift 21cm Fluctuations

abstract:
  Fluctuations in the 21cm brightness from cosmic hydrogen at redshifts z > 6
were sourced by the primordial density perturbations from inflation as well as
by the radiation from galaxies. We propose a method to separate these
components based on the angular dependence of the 21cm fluctuation power
spectrum. Peculiar velocities increase the power spectrum by a factor of ~ 2
compared to density fluctuations alone, and introduce an angular dependence in
Fourier space. The resulting angular structure relative to the line of sight
facilitates a simple separation of the power spectrum into several components,
permitting an unambiguous determination of the primordial power spectrum of
density fluctuations, and of the detailed properties of all astrophysical
sources of 21cm fluctuations. We also demonstrate that there is no significant
information to be gained from 21cm measurements on large angular scales. Thus,
observational analyses can be confined to small angular areas where projection
effects are negligible, and theoretical predictions should focus on the
three-dimensional power spectrum of 21cm fluctuations.


title:
A Porosity-Length Formalism for Photon-Tiring-Limited Mass Loss from
  Stars Above the Eddington Limit

abstract:
  We examine radiatively driven mass loss from stars near and above the
Eddington limit (Ledd). We begin by reviewing the instabilities that are
expected to form extensive structure near Ledd. We investigate how this
"porosity" can reduce the effective coupling between the matter and radiation.
Introducing a new "porosity-length'' formalism, we derive a simple scaling for
the reduced effective opacity, and use this to derive an associated scaling for
the porosity-moderated, continuum-driven mass loss rate from stars that
formally exceed Ledd. For a simple super-Eddington model with a single porosity
length that is assumed to be on the order of the gravitational scale height,
the overall mass loss is similar to that derived in previous porosity work.
This is much higher than is typical of line-driven winds, but is still only a
few percent of the photon tiring limit--for which the luminosity becomes
insufficient to carry the flow out of the gravitational potential. To obtain
still stronger mass loss that approaches observationally inferred values near
this limit, we introduce a power-law-porosity model in which the associated
structure has a broad range of scales. We show that the mass loss rate can be
enhanced by a factor that increases with the Eddington parameter Gamma, such
that for moderately large Gamma (> 3-4), mass loss rates could approach the
photon tiring limit. Together with the ability to drive quite fast outflow
speeds, the derived mass loss could explain the large inferred mass loss and
flow speeds of giant outbursts in eta Carinae and other LBV stars.


title:
Constraining Dark Energy with X-ray Galaxy Clusters, Supernovae and the
  Cosmic Microwave Background

abstract:
  We present new constraints on the evolution of dark energy from an analysis
of Cosmic Microwave Background, supernova and X-ray galaxy cluster data. Our
analysis employs a minimum of priors and exploits the complementary nature of
these data sets. We examine a series of dark energy models with up to three
free parameters: the current dark energy equation of state w_0, the early time
equation of state w_et and the scale factor at transition, a_t. From a combined
analysis of all three data sets, assuming a constant equation of state and that
the Universe is flat, we measure w_0=-1.05+0.10-0.12. Including w_et as a free
parameter and allowing a_t to vary over the range 0.5<a_t<0.95 where the data
sets have discriminating power, we measure w_0=-1.27+0.33-0.39 and
w_et=-0.66+0.44-0.62. We find no significant evidence for evolution in the dark
energy equation of state parameter with redshift. Marginal hints of evolution
in the supernovae data become less significant when the cluster constraints are
also included in the analysis. The complementary nature of the data sets leads
to a tight constraint on the mean matter density, Omega_m and alleviates a
number of other parameter degeneracies, including that between the scalar
spectral index n_s, the physical baryon density Omega_bh^2 and the optical
depth tau. This complementary nature also allows us to examine models in which
we drop the prior on the curvature. For non-flat models with a constant
equation of state, we measure w_0=-1.09+0.12-0.15 and Omega_de=0.70+-0.03. Our
analysis includes spatial perturbations in the dark energy fluid, assuming a
sound speed c_s^2 =1. For our most general dark energy model, not including
such perturbations would lead to spurious constraints on w_et which would be
tighter by approximately a factor two with the current data. (abridged)


title:
Properties of Two Hypernovae Entering the Nebular Phase: SN 1997ef and
  SN 1997dq

abstract:
  The two peculiar Type Ic supernovae (SNe) 1997ef and 1997dq are shown to have
very similar photometric and spectral evolution in the epochs when both SNe are
observed (i.e. beyond $\sim 80$ days after the explosion). The early light
curves and spectra of SN 1997ef suggested that this was a ``hypernova,'' or
``SN 1998bw-like Type Ic supernova.'' The fact that the two SNe are very
similar allows us to extend the time coverage of this type of event, since SN
1997dq, unlike SN 1997ef, was observed well into the nebular phase. In contrast
to SN 1998bw, the spectra of these two SNe did not become fully nebular until
almost one year after the explosion. During a long transition phase, lasting at
least 6 months, the SNe developed nebular emission in lines of [\OI] and
[\CaII], but at the same time they retained an underlying, photospheric-type
spectrum, originating at very low velocities. Spectral synthesis techniques are
used to model the spectrum of SN 1997dq, suggesting that it produced $\sim 0.16
\Msun$ of \Nifs, and that a significant fraction of this is located in a dense,
low-velocity inner region.


title:
Inter-cluster Filaments of Galaxies Programme: Abundance and
  Distribution of Filaments in the 2dFGRS Catalogue

abstract:
  Filaments of galaxies are known to stretch between galaxy clusters at all
redshifts in a complex manner. In this Letter, we present an analysis of the
frequency and distribution of inter-cluster galaxy filaments selected from the
2dF Galaxy Redshift Survey. Out of 805 cluster-cluster pairs, we find at least
40 per cent have bone-fide filaments. We introduce a filament classification
scheme and cast the filaments into several types according to their visual
morphology: straight (lying on the cluster-cluster axis; 37 per cent), warped
or curved (lying off the cluster-cluster axis; 33 per cent), sheets (planar
configurations of galaxies; 3 per cent), uniform (1 per cent) and irregular (26
per cent). We find that straight filaments are more likely to reside between
close cluster pairs and they become more curved with increasing cluster
separation. This curving is toward a larger mass concentration in general. We
also show that the more massive a cluster is, the more likely it is to have a
larger number of filaments. Our results are found to be consistent with a
Lambda cold dark matter cosmology.


title: A supernova origin for dust in a high-redshift quasar

abstract:
  Interstellar dust plays a crucial role in the evolution of the Universe by
assisting the formation of molecules, by triggering the formation of the first
low-mass stars, and by absorbing stellar ultraviolet-optical light and
subsequently re-emitting it at infrared/millimetre wavelengths. Dust is thought
to be produced predominantly in the envelopes of evolved (age >1 Gyr), low-mass
stars. This picture has, however, recently been brought into question by the
discovery of large masses of dust in the host galaxies of quasars at redshift
z>6, when the age of the Universe was less than 1 Gyr. Theoretical studies,
corroborated by observations of nearby supernova remnants, have suggested that
supernovae provide a fast and efficient dust formation environment in the early
Universe. Here we report infrared observations of a quasar at redshift 6.2,
which are used to obtain directly its dust extinction curve. We then show that
such a curve is in excellent agreement with supernova dust models. This result
demonstrates a supernova origin for dust in this high-redshift quasar, from
which we infer that most of the dust at high redshifts has probably the same
origin.


title: Gravitational Waves from Rotating Proto-Neutron Stars

abstract:
  We study the effects of rotation on the quasi normal modes (QNMs) of a newly
born proto neutron star (PNS) at different evolutionary stages, until it
becomes a cold neutron star (NS). We use the
  Cowling approximation, neglecting spacetime perturbations, and consider
different models of evolving PNS. The frequencies of the modes of a PNS are
considerably lower than those of a cold NS, and are further lowered by
rotation; consequently, if QNMs were excited in a sufficiently energetic
process, they would radiate waves that could be more easily detectable by
resonant-mass and interferometric detectors than those emitted by a cold NS. We
find that for high rotation rates, some of the g-modes become unstable via the
CFS instability; however, this instability is likely to be suppressed by
competing mechanisms before emitting a significant amount of gravitational
waves.


title:
Local kinematics of K and M giants from Coravel/Hipparcos/Tycho-2 data.
  Revisiting the concept of superclusters

abstract:
  The availability of the Hipparcos Catalogue triggered many kinematic and
dynamical studies of the solar neighbourhood. Nevertheless, those studies
generally lacked the third component of the space velocities, i.e., the radial
velocities. This work presents the kinematic analysis of 5952 K and 739 M
giants in the solar neighbourhood which includes for the first time radial
velocity data from a large survey performed with the CORAVEL
spectrovelocimeter. It also uses proper motions from the Tycho-2 catalogue,
which are expected to be more accurate than the Hipparcos ones. The UV-plane
constructed from these data for the stars with precise parallaxes reveals a
rich small-scale structure, with several clumps corresponding to the Hercules
stream, the Sirius moving group, and the Hyades and Pleiades superclusters. A
maximum-likelihood method, based on a bayesian approach, has been applied to
the data, in order to make full use of all the available stars and to derive
the kinematic properties of these subgroups. Isochrones in the
Hertzsprung-Russell diagram reveal a very wide range of ages for stars
belonging to these groups. These groups are most probably related to the
dynamical perturbation by transient spiral waves rather than to cluster
remnants. A possible explanation for the presence of young clusters in the same
area of the UV-plane is that they have been put there by the spiral wave
associated with their formation, while the kinematics of the older stars of our
sample has also been disturbed by the same wave. The term "dynamical stream"
for the kinematic groups is thus more appropriate than the traditional term
"supercluster" since it involves stars of different ages, not born at the same
place nor at the same time.


title:
New estimates of the contribution of Wolf--Rayet stellar winds to the
  Galactic 26Al

abstract:
  We present new yields of 26Al from Wolf--Rayet stellar winds based on
rotating stellar models which account well for numerous observed properties of
massive stars. We study the impacts on the yields of a change of initial mass,
metallicity and initial rotation velocity. We also consider the effects of a
change of mass loss rates during the Wolf--Rayet phase. We show that for
surface rotation velocities during the core H--burning phase matching to the
observed ones, the quantity of 26Al ejected by a star of a given initial mass
and metallicity is roughly doubled when the effects of rotation are taken into
account. The metallicity dependence of the yield is, on the other hand, very
similar to that obtained from non--rotating models. We estimate that at least
about 20% to 50% (e.g. 0.6 --1.4 Msun) of the live 26Al detected in the
Milky--Way originates from Wolf--Rayet stellar winds. We show the importance of
a good knowledge of the present metallicity gradient and star formation rate in
our galaxy for modeling both the variation of the 26Al surface density with the
galactocentric distance and the global contribution of the Wolf--Rayet stellar
winds to the present galactic mass of 26Al.


title: Interpretation of abundance ratios

abstract:
  In this paper we discuss abundance ratios and their relation to stellar
nucleosynthesis and other parameters of chemical evolution models, reviewing
and clarifying the correct use of the observed abundance ratios in several
astrophysical contests. In particular, we start from the well known fact that
abundance ratios depend on stellar yields, initial mass function and stellar
lifetimes and we show, by means of specific examples, that in some cases it is
not correct to infer constraints on the contributions from different SN types
(Ia, II), and particularly on different sets of yields, in the absence of a
complete chemical evolution model taking into account stellar lifetimes. In
spite of the fact that some of these results should be well known, we believe
that it is useful to discuss the meaning of abundance ratios in the light of
severel recent claims based upon an incorrect interpretation of observed
abundance ratios. In particular, the procedure, often used in the recent
literature, of deriving directly conclusions about stellar nucleosynthesis,
just by relating abundance ratios to yield ratios, implicitly assumes the
instantaneous recycling approximation (I.R.A.). This approximation is clearly
not correct when one analyzes the contributions of SNIa relative to SNII as
functions of cosmic time. In this paper we show that the uncertainty which
arises from adopting this oversimplified procedure in a variety of
astrophysical objects, such as elliptical galaxies, the intracluster medium and
high redshift objects, does not allow us to draw any firm conclusion, and that
the differences between abundance ratios predicted by models with I.R.A. and
models with detailed stellar lifetimes is of the same order as the differences
between different sets of yields. (Abridged)


title: The Solar Neighbourhood XI: The trigonometric parallax of SCR 1845--6357

abstract:
  We present a trigonometric parallax for the nearby star SCR1845--6357, an
extremely red high proper motion object discovered by Hambly et al. (2004) and
identified via accurate photoelectric photometry and spectroscopy to be an M8.5
dwarf with a photometric parallax of $4.6\pm0.8$ pc by Henry et al. (2004).
Using methods similar to those described in Deacon & Hambly (2001) we have
derived a full astrometric solution from SuperCOSMOS scans of eight survey and
non--survey Schmidt photographs held in the United Kingdom Schmidt Telescope
Unit plate library. We calculate the trigonometric parallax to be
$\pi=282\pm23$ mas yielding a distance of $3.5\pm0.3$ pc which implies an
absolute K$_{s}$ magnitude of 10.79. This distance calculation places
SCR1845--6357 as the 16th closest stellar system to the Sun.


title:
Exploring the Divisions and Overlap between AGB and Super-AGB Stars and
  Supernovae

abstract:
  We discuss the mass ranges over which we find AGB and super-AGB stars. The
most massive super-AGB stars are candidate progenitors for type II
core-collapse SNe. We discuss the two supernovae, SN1980K and SN2003gd that
provide some restrictions on the upper mass limit of super-AGB stars.


title:
Energy Injection Episodes in Gamma Ray Bursts: The Light Curves and
  Polarization Properties of GRB 021004

abstract:
  Several GRB afterglow light curves deviate strongly from the power law decay
observed in most bursts. We show that these variations can be accounted for by
including refreshed shocks in the standard fireball model previously used to
interpret the overall afterglow behavior. As an example we consider GRB 021004
that exhibited strong light curve variations and has a reasonably well
time-resolved polarimetry. We show that the light curves in the R-band, X-rays
and in the radio can be accounted for by four energy injection episodes in
addition to the initial event. The polarization variations are shown to be a
consequence of the injections.


title: From First Galaxies to QSOs: feeding the baby monsters

abstract:
  We present a physical model for the coevolution of massive spheroidal
galaxies and active nuclei at their centers. Supernova heating is increasingly
effective in slowing down the star formation and in driving gas outflows in
smaller and smaller dark matter halos. Thus the more massive protogalaxies
virializing at early times are the sites of faster star formation. The
correspondingly higher radiation drag causes a faster angular momentum loss by
the gas and induces a larger accretion rate onto the central black hole. In
turn, the kinetic energy of the outflows powered by the active nuclei can
unbind the residual gas in a time shorter for larger halos. The model accounts
for a broad variety of dynamical, photometric and metallicity properties of
early-type galaxies, for the M_BH -- \sigma relation and for the local
supermassive black-hole mass function.


title: High-velocity OVI in and near the Milky Way

abstract:
  The Far Ultraviolet Spectroscopic Explorer (FUSE) has observed over three
hundred fifty sightlines to extragalactic targets. About one hundred fifty of
these are of sufficient quality to measure OVI absorption in and near the Milky
Way. High-velocity OVI absorption is detected in about 80% of the sightlines,
with the detection rate going up for sightlines with higher signal-to-noise
ratios. OVI is almost always seen in directions with previously known HI HVCs,
including HVCs complex C, complex A, complex WD, the Magellanic Stream, and the
Outer Arm. Studies of several sightlines through complex C suggest that the OVI
absorption is produced in conductive interfaces between the cool HVC and a
hotter surrounding medium, most likely a corona around the Milky Way. The OVI
detections associated with the Magellanic Stream imply that this hot corona has
a radius of at least 50 kpc. About half of the detections of high-velocity OVI
are in directions where no high-velocity HI was previously known. Some of these
are probably associated with the Magellanic Stream, others may represent Local
Group gas. Still others often show up as a distinct wing on the low-velocity
absorption; these may either represent an outflow from the Milky Way associated
with the Galactic Fountain, they may be extragalactic HVCs, or they may be
tracing a wind from the Galactic Center. Distance limits to the high-velocity
OVI are scarce, but at least one of the clouds appear to be more distant than 4
kpc.


title:
Detection of hard X-ray pulsations and a strong iron K_beta emission
  line during an extended low state of GX 1+4

abstract:
  We present here results obtained from a detailed timing and spectral analysis
of three BeppoSAX observations of the binary X-ray pulsar GX 1+4 carried out in
August 1996, March 1997, and August 2000. In the middle of the August 2000
observation, the source was in a rare low intensity state that lasted for about
30 hours. Though the source does not show pulsations in the soft X-ray band
(1.0-5.5 keV) during the extended low state, pulsations are detected in
5.5-10.0 keV energy band of the MECS detector and in hard X-ray energy bands
(15-150 keV) of the PDS instrument. Comparing the 2-10 keV flux during this low
state with the previously reported low states in GX 1+4, we suggest that the
propeller regime in GX 1+4 occurs at a lower mass accretion rate than reported
earlier. Broad-band (1.0-150 keV) pulse averaged spectroscopy reveals that the
best-fit model comprises of a Comptonized continuum along with an iron K_alpha
emission line. A strong iron K_beta emission line is detected for the first
time in GX 1+4 during the extended low state of 2000 observation with
equivalent width of ~550 eV. The optical depth and temperature of the
Comptonizing plasma are found to be identical during the high and low intensity
states whereas the hydrogen column density and the temperature of the seed
photons are higher during the low state. We also present results from pulse
phase resolved spectroscopy during the high and low flux episodes.


title: FUSE Observations of the Dwarf Nova SW UMa During Quiescence

abstract:
  We present spectroscopic observations of the short-period cataclysmic
variable SW Ursa Majoris, obtained by the Far Ultraviolet Spectroscopic
Explorer (FUSE) satellite while the system was in quiescence. The data include
the resonance lines of O VI at 1031.91 and 1037.61 A. These lines are present
in emission, and they exhibit both narrow (~ 150 km/s) and broad (~ 2000 km/s)
components. The narrow O VI emission lines exhibit unusual double-peaked and
redshifted profiles. We attribute the source of this emission to a cooling flow
onto the surface of the white dwarf primary. The broad O VI emission most
likely originates in a thin, photoionized surface layer on the accretion disk.
We searched for emission from H_2 at 1050 and 1100 A, motivated by the
expectation that the bulk of the quiescent accretion disk is in the form of
cool, molecular gas. If H_2 is present, then our limits on the fluxes of the
H_2 lines are consistent with the presence of a surface layer of atomic H that
shields the interior of the disk. These results may indicate that accretion
operates primarily in the surface layers of the disk in SW UMa. We also
investigate the far-UV continuum of SW UMa and place an upper limit of 15,000 K
on the effective temperature of the white dwarf.


title: Microlensing Characterization of Wide-Separation Planets

abstract:
  With their excellent photometric precision and dramatic increase in
monitoring frequency, future microlensing survey experiments are expected to be
sensitive to very short time-scale, isolated events caused by free-floating and
wide-separation planets with mass as low as a few lunar masses. We estimate the
probability of measuring the Einstein radius \theta_E for bound and
free-floating planets. We carry out detailed simulations of the planetary
events expected in next-generation surveys and estimate the resulting
uncertainty in \theta_E for these events. We show that, for main-sequence
sources and Jupiter-mass planets, the caustic structure of wide-separation
planets with projected separations of < 20 AU substantially increases the
probability of measuring the dimensionless source size and thus determining
\theta_E compared to the case of unbound planets. In this limit where the
source is much smaller than the caustic, the effective cross-section to measure
\theta_E to 10% is ~25% larger than the full width of the caustic. Measurement
of the lens parallax is possible for low-mass planetary events by combined
observations from the ground and a satellite located in an L2 orbit; this would
complete the mass measurements for such wide-separation planets. Finally,
short-duration events caused by bound planets can be routinely distinguished
from those caused by free-floating planets for planet-star separations < 20 AU
from either the deviations due to the planetary caustic or (more often) the
low-amplitude bump from the magnification due to the parent star.


title:
Primordial Power Spectrum's Calculation and the Upper Bound on the
  Number of E-foldings of Inflation

abstract:
  In numerical calculations of the primordial power spectrum of perturbations
produced during inflation, for very little wavenumber $k$s, to implement the
initial conditions required of the perturbation mode functions consistently, we
must let the universe experience more e-foldings of inflation than that
required of it to solve the horizon, flatness and other pre-inflation problems.
However, if the number of e-foldings of inflation has an upper bound, then for
perturbations at scales greater than some critical value, the initial
conditions required of the mode functions cannot be implemented physically.
Because at the inflation beginning point, these perturbation modes lie outside
the horizon. We propose that such perturbations do not contribute to the
Cosmological Microwave Background Anisotropy (CMBA). Under this proposition,
the exceptional lowness of the observed little $l$ muli-poles of CMBA is
reproduced numerically. In Linde's $\phi^2$ model, the upper bound on the
number of e-foldings of inflation is determined to be 65 approximately.


title:
Exploring the Gamma Ray Horizon with the next generation of Gamma Ray
  Telescopes. Part 3: Optimizing the observation schedule of gamma-ray sources
  for the extraction of cosmological parameters

abstract:
  The optimization of the observation schedule of gamma-ray emitters by the new
generation of Cherenkov Telescopes to extract cosmological parameters from the
measurement of the Gamma Ray Horizon at different redshifts is discussed. It is
shown that improvements over 30% in the expected cosmological parameter
uncertainties can be achieved if instead of equal-observation time, dedicated
observation schedules are applied.


title:
Chandra detection of ejecta in the small-diameter supernova remnant
  G349.7+0.2

abstract:
  We present high-resolution X-ray observations of the small-diameter supernova
remnant (SNR) G349.7+0.2 with the Chandra X-ray Observatory. The overall SNR
spectrum can be described by two spectral components. The soft component is in
ionization equilibrium and has a temperature of ~0.8 keV; the hard spectral
component has a temperature of ~1.4 keV, an ionization timescale of ~5x10^{11}
cm{-3}s and enhanced abundances of Si. The spatially resolved spectral modeling
shows that S may also be enhanced, at least in some regions. The enhanced
abundances clearly point to the presence of an ejecta component in this
remnant. The X-ray morphology of G349.7+0.2 is strikingly similar to that at
radio wavelengths - an irregular shell with a brighter eastern side - which is
consistent with expansion in a medium with a large scale density gradient. The
remnant is known to be interacting with a molecular cloud (from the presence of
OH(1720 MHz) masers), but this interaction is probably limited to the central
portion of the SNR, as seen in SNR IC 443. We found that HI clouds are present
in the SNR region, which supports the notion that G349.7+0.2 belongs to a class
of remnants evolving in the intercloud medium (such are IC 443 and W44,
Chevalier 1999), which is also responsible for the remnant's morphology.
G349.7+0.2 does not have the mixed-morphology found for other maser-emitting
SNRs studied to date in X-rays, but its morphology can be explained by a
projection model for mixed-morphology SNRs. We have identified a point source
close to the center of the SNR with a luminosity of Lx(0.5-10.0 keV) ~
(0.2-2.3)x10^{34} d_{22} erg/s, which is consistent with that of the compact
central objects found in a few other Galactic SNRs.


title: Pre-Maximum Spectropolarimetry of the Type Ia SN 2004dt

abstract:
  We report observations of SN 2004dt obtained with the Very Large Telescope of
the European Southern Observatory on August 13.30, 2004 when the supernova was
more than a week before optical maximum. SN 2004dt showed strong lines of
\ion{O}{1}, \ion{Mg}{2}, \ion{Si}{2}, and \ion{Ca}{2} with typical velocities
of absorption minimum around 17,000 \kms. The line profiles show material
moving at velocities as high as 25,000 \kms in these lines. The observations
also reveal absorption lines from \ion{S}{2} and \ion{Si}{3} with a velocity of
only 11,000 \kms. The highest velocity in the \ion{S}{2} features can be traced
no higher than 15,000 \kms, much lower than those of O, Mg, Si, and Ca. SN
2004dt has a polarization spectrum unlike any previously observed. The
variation of the polarization across some \ion{Si}{2} lines approaches 2%,
making SN 2004dt the most highly polarized SN Ia ever observed. In contrast,
the strong line of O I at 777.4 nm shows little or no polarization signature.
The degree of polarization points to a richly-structured partially burned
silicon layer with substantial departure from spherical symmetry. A geometry
that would account for the observations is one in which the distribution of
oxygen is essentially spherically symmetric, but with bubbles of
intermediate-mass elements with significant opacity within the oxygen
substrate.


title: Magnetized initial conditions for CMB anisotropies

abstract:
  This paper introduces a systematic treatment of the linear theory of scalar
gravitational perturbations in the presence of a fully inhomogeneous magnetic
field. The analysis is conducted both in the synchronous and in the conformally
Newtonian gauges. The cosmological plasma is assumed to be composed of cold
dark mattter, baryons, photons, neutrinos. The problem of super-horizon initial
conditions for the fluid variables of the various species and for the coupled
system of Boltzmann-Einstein equations is discussed in the presence of an
inhomogeneous magnetic field. The tight coupling approximation for the
Boltzmann hierarchy is extended to the case where gravitating magnetic fields
are included.


title:
Magnetic-Driven Winds from Post-AGB Stars: Solutions for High Speed
  Winds and Extreme Collimation

abstract:
  This paper explores the effects of post-AGB winds driven solely by magnetic
pressure from the stellar surface. It is found that winds can reach high speeds
under this assumption, and lead to the formation of highly collimated
proto-planetary nebulae. Bipolar knotty jets with periodic features and
constant velocity are well reproduced by the models. Several wind models with
terminal velocities from a few tens of $\kms$ up to $10^3$ $\kms$ are
calculated, yielding outflows with linear momenta in the range $10^{36}-10^{40}
\gcms$, and kinetic energies in the range $10^{42}-10^{47} $ erg. These results
are in accord with recent observations of proto-planetary nebulae that have
pointed out serious energy and momentum deficits if radiation pressure is
considered as the only driver for these outflows. Our models strengthen the
notion that the large mass-loss rates of post-AGB stars, together with the
short transition times from the late AGB to the planetary nebula stage, could
be directly linked with the generation of strong magnetic fields during this
transition stage.


title: Exorcising w < -1

abstract:
  We show that the combined dimming of Type Ia supernovae induced by both a
cosmological constant and the conversion of photons into axions in
extra-galactic magnetic fields can impersonate dark energy with an equation of
state w < -1. An observer unaware of the presence of photon-axion conversion
would interpret the additional dimming as cosmic acceleration faster than that
induced by a cosmological constant alone. We find that this mechanism can mimic
equations of state as negative as w \simeq - 1.5. Our model does not have any
ghosts, phantoms and the like. It is fully consistent with the conventional
effective field theory in curved space, and all existing observational
constraints on the axions are obeyed.


title: Simulating the Spitzer mid-IR color-color diagrams

abstract:
  We use a simple parameterization of the mid-IR spectra of a wide range of
galaxy types in order to predict their distribution in the Infrared Array
Camera (IRAC) 3.6um, 4.5um, 5.8um, and 8.0um and Multiband Photometer for
Spitzer (MIPS) 24um color-color diagrams. We distinguish three basic spectral
types by the energetically dominant component in the 3--12 micron regime:
stellar-dominated; PAH-dominated; and continuum-dominated. We have used a
Markov chain Monte Carlo (MCMC) approach to arrive at a more systematic and
robust representation of the mid-IR spectra of galaxies than more traditional
approaches. We find that IRAC color-color plots are well suited to
distinguishing the above spectral types, while the addition of 24 micron data
allows us to suggest practical 3-color cuts which preferentially select higher
redshift sources of specific type. We compare our simulations with the
color-color plot obtained by the Spitzer First Look Survey (FLS) and find
reasonable agreement. Lastly, we discuss other applications as well as future
directions for this work.


title: Three-Dimensional Delayed-Detonation Model of Type Ia Supernova

abstract:
  We study a Type Ia supernova explosion using large-scale three-dimensional
numerical simulations based on reactive fluid dynamics with a simplified
mechanism for nuclear reactions and energy release. The initial deflagration
stage of the explosion involves a subsonic turbulent thermonuclear flame
propagating in the gravitational field of an expanding white dwarf. The
deflagration produces an inhomogeneous mixture of unburned carbon and oxygen
with intermediate-mass and iron-group elements in central parts of the star.
During the subsequent detonation stage, a supersonic detonation wave propagates
through the material unburned by the deflagration. The total energy released in
this delayed-detonation process, (1.3-1.6)x10^51 ergs, is consistent with a
typical range of kinetic energies obtained from observations. In contrast to
the deflagration model that releases only about 0.6x10^51 ergs, the
delayed-detonation model does not leave carbon, oxygen, and intermediate-mass
elements in central parts of a white dwarf. This removes the key disagreement
between three-dimensional simulations and observations, and makes a delayed
detonation the mostly likely mechanism for Type Ia supernova explosions.


title: Inverse-Scattering Theory and the Density Perturbations from Inflation

abstract:
  Inflationary cosmology provides a successful paradigm for solving several
problems, notably the generation of density perturbations which seed the
formation of observed cosmic structure. We show how to use inverse scattering
theory as the basis for the inflationary reconstruction program, the goal of
which is to gain information about the physics which drives inflation. Inverse
scattering theory provides an effective and well-motivated procedure, having a
sound mathematical basis and being of sufficient generality that it can be
considered the foundation for a non-parametric reconstruction program. We show
how simple properties of the power spectrum translate directly into statements
about the evolution of the background geometry during inflation.


title:
X-ray Properties of Lyman Break Galaxies in the Great Observatories
  Origins Deep Survey

abstract:
  We constrain the X-ray emission properties of Lyman break galaxies (LBGs) at
z ~ 3-6 using the 2 Ms Chandra Deep Field-North and 1 Ms Chandra Deep
Field-South. Large samples of LBGs were discovered using HST as part of the
Great Observatories Origins Deep Survey (GOODS). Deep optical and X-ray imaging
over the GOODS fields have allowed us to place the most significant constraints
on the X-ray properties of LBGs to date. Mean X-ray properties of 449, 1734,
629, and 247 LBGs with z ~ 3, 4, 5, and 6, respectively, were determined using
stacking techniques. When stacked, we detect X-ray emission from LBGs at z ~ 3
(7 sigma) and from an optically bright subset (brightest 25%) of LBGs at z ~ 4
(3 sigma); the latter is the highest redshift detection yet for "normal"
galaxies in the X-ray band. The effective exposure times for these stacked
observations are 0.7 and 0.5 Gs, respectively. The derived average rest-frame
2.0-8.0 keV luminosities are 1.5 and 1.4 x 10^41 erg s^-1, respectively. X-ray
emission from these LBGs is likely due to high mass X-ray binaries (HMXBs) and
Type II supernovae; the corresponding star formation rates are 85-240 M_sol
yr^-1. The X-ray to B-band mean luminosity ratio (Lx/LB) at z~3 is somewhat
elevated with respect to that measured for starburst galaxies in the local
Universe. When stacking full samples of LBGs at z ~ 4, 5, and 6 we do not
obtain significant detections and derive rest-frame 2.0-8.0 keV luminosity
upper limits of 0.9, 2.8, and 7.1 x 10^41 erg s^-1, respectively. These upper
limits constrain any widespread AGN activity in these objects to be modest at
best. Furthermore, we find that ~ 0.5% of our LBGs from z ~ 3-6 are detected
individually in the X-ray band. Continued ...


title: The stellar IMF of Galactic clusters and its evolution

abstract:
  We show that one can obtain a good fit to the measured main sequence mass
function (MF) of a large sample of Galactic clusters (young and old) with a
tapered Salpeter power law distribution function with an exponential
truncation. The average value of the power law index is very close to Salpeter
(~2.3), whereas the characteristic mass is in the range 0.1 - 0.5 Msolar and
does not seem to vary in a systematic way with the present cluster parameters
such as metal abundance and central concentration. However, a remarkable
correlation with age is seen, in that the peak mass of young clusters increases
with it. This trend does not extend to globular clusters, whose peak mass is
firmly at ~0.35 Msolar. This correlation is due to the onset of mass
segregation following early dynamical interactions in the loose cluster cores.
Differences between globular and younger clusters may depend on the initial
environment of star formation, which in turn affects their total mass.


title: Neutron Stars With A Quark Core. I. Equations Of State

abstract:
  An extensive set of realistic equations of state for superdense matter with a
quark phase transition is derived on the basis of the three equations of state
for neutron matter and the eight variants of strange quark-gluon plasmas in the
MIT quark bag model. The characteristics of the phase transitions are described
and the calculated equations of state with a density jump are studied in
detail.


title: GOODS Discovery of a Significant Population of Obscured AGN

abstract:
  We analysed the optical and infrared properties of X-ray sources in the Great
Observatories Origins Deep Survey (GOODS), a deep multiwavelength survey
covering 0.1 square degrees in two fields. The HST ACS data are well explained
by a unified AGN scheme that postulates roughly 3 times as many obscured as
unobscured AGN, as are the spectroscopic and photometric redshift distributions
once selection effects are considered. Our model predicts infrared number
counts of AGN that agree well with the preliminary Spitzer data, confirming
that large numbers of obscured AGN are present in the early Universe (z>1).


title: Fading of the Transient Anomalous X-ray Pulsar XTE J1810-197

abstract:
  Three observations of the 5.54 s Transient Anomalous X-ray Pulsar XTE
J1810-197 obtained over 6 months with the Newton X-Ray Multi-Mirror Mission
(XMM-Newton) are used to study its spectrum and pulsed light curve as the
source fades from outburst. The decay is consistent with an exponential of time
constant 300 days, but not a power law as predicted in some models of sudden
deep crustal heating events. All spectra are well fitted by a blackbody plus a
steep power law, a problematic model that is commonly fitted to anomalous X-ray
pulsars (AXPs). A two-temperature blackbody fit is also acceptable, and better
motivated physically in view of the faint optical/IR fluxes, the X-ray pulse
shapes that weakly depend on energy in XTE J1810-197, and the inferred emitting
areas that are less than or equal to the surface area of a neutron star. The
fitted temperatures remained the same while the flux declined by 46%, which can
be interpreted as a decrease in area of the emitting regions. The pulsar
continues to spin down, albeit at a reduced rate of (5.1+/-1.6)x10^{-12} s
s^{-1}. The inferred characteristic age Tau_c = P/2Pdot ~17,000 yr, magnetic
field strength B_s ~1.7x10^{14} G, and outburst properties are consistent with
both the outburst and quiescent X-ray luminosities being powered by magnetic
field decay, i.e., XTE J1810-197 is a magnetar.


title: Globular Clusters with Dark Matter Halos. I. Initial Relaxation

abstract:
  In a series of two papers, we test the primordial scenario of globular
cluster formation using results of high-resolutions N-body simulations. In this
first paper we study the initial relaxation of a stellar core inside a live
dark matter minihalo in the early universe. Our dark-matter dominated globular
clusters show features which are usually attributed to the action of the tidal
field of the host galaxy. Among them are the presence of an apparent cutoff
("tidal radius") or of a "break" in the outer parts of the radial surface
brightness profile, and a flat line-of-sight velocity dispersion profile in the
outskirts of the cluster. The apparent mass-to-light ratios of our hybrid
(stars + dark matter) globular clusters are very close to those of purely
stellar clusters. We suggest that additional observational evidence such as the
presence of obvious tidal tails is required to rule out the presence of
significant amounts of dark matter in present day globular clusters.


title: Globular Clusters with Dark Matter Halos. II. Evolution in Tidal Field

abstract:
  In this second paper in our series, we continue to test primordial scenarios
of globular cluster formation which predict that globular clusters formed in
the early universe in the potential of dark matter minihalos. In this paper we
use high-resolution N-body simulations to model tidal stripping experienced by
primordial dark-matter dominated globular clusters in the static gravitational
potential of the host dwarf galaxy. We test both cuspy Navarro-Frenk-White
(NFW) and flat-core Burkert models of dark matter halos. Our primordial
globular cluster with an NFW dark matter halo survives severe tidal stripping,
and after 10 orbits is still dominated by dark matter in its outskirts. Our
cluster with Burkert dark matter halo loses almost all its dark matter to tidal
stripping, and starts losing stars at the end of our simulations. The results
of this paper reinforce our conclusion in Paper I that current observations of
globular clusters are consistent with the primordial picture of globular
cluster formation.


title:
Effects of chemical composition and thermohaline mixing on the accreting
  components for low--mass close binaries: application to blue stragglers

abstract:
  We studied the effects of surface composition and thermohaline mixing caused
by secular instability on the accreting components for low--mass binaries and
applied the results on a short-orbital-period BS F190 in the old cluster M67.
The results indicate no distinction in surface composition between the models
with and without thermohaline mixing during Roche lobe overflow, but we still
see the divergences of evolutionary tracks on HRD and CMD. The change of
surface composition makes the gainer bluer and smaller than the ones with
original surface composition while thermohaline mixing lessens the effect
slightly. If thermohaline mixing were to act instantaneously, the effect would
be lessened more. Our calculation shows that case A and case B mass transfer
may produce BSs in short- or relatively short-orbital-period binaries
(including Algol systems), and that CNO abundance abnormalities could be
observed in these products. Our simulation of F190 shows that the primary's
mass $M_{\rm 1i}$ of the appropriate models is located in the range of 1.40 to
1.45$M_{\odot}$ with initial mass ratio $q_{\rm i}=1.5$ and initial orbital
period $P_{\rm i}=0.8$ days, indicating that case A is a more likely
evolutionary channel than case B to form this object. The simulation also shows
that it is very likely that F190 is still in a slow stage of mass transfer. As
a consequence, obvious CNO abundance abnormalities should be observed for the
object.


title: The Low X-Ray State of LS 5039 / RX J1826.2-1450

abstract:
  Recent XMM-Newton and Chandra observations of the high mass X-ray binary LS
5039 / RX J1826.2-1450 caught the source in a faint X-ray state. In contrast
with previous RXTE observations, we fail to detect any evidence of iron line
emission. We also fail to detect X-ray pulsations. The X-ray spectrum can be
well fitted by a simple powerlaw, slightly harder than in previous
observations, and does not require the presence of any additional disk or
blackbody component. XMM-Newton data imply an X-ray photoelectric absorption
($N_{\rm H} \sim 7 \times 10^{21}$ cm$^{-2}$) consistent with optical
reddening, indicating that no strong local absorption occurs at the time of
these observations. We discuss possible source emission mechanisms and
hypotheses on the nature of the compact object, giving particular emphasis to
the young pulsar scenario.


title:
Indirect imaging of nonradial pulsations in a rapidly oscillating Ap
  star

abstract:
  Many types of stars show periodic variations of radius and brightness, which
are commonly referred to as `stellar pulsations'. Observed pulsational
characteristics are determined by fundamental stellar parameters. Consequently,
investigations of stellar pulsations provide a unique opportunity to verify and
refine our understanding of the evolution and internal structure of stars.
However, a key boundary condition for this analysis -- precise information
about the geometry of pulsations in the outer stellar envelopes -- has been
notoriously difficult to secure. Here we demonstrate that it is possible to
solve this problem by constructing an `image' of the pulsation velocity field
from time series observations of stellar spectra. This technique is applied to
study the geometry of nonradial pulsations in a prototype magnetic oscillating
(roAp) star HR 3831. Our velocity map directly demonstrates an alignment of
pulsations with the axis of the global magnetic field and reveals a significant
magnetically induced distortion of pulsations. This observation constitutes a
long-sought solution of the problem of the pulsation geometry of roAp stars and
enables very stringent tests of the recent theories of stellar magneto-acoustic
oscillations.


title:
Novel Geometrical Models of Relativistic Stars III. The Point Particle
  Idealization

abstract:
  We describe a novel class of geometrical models of relativistic stars. Our
approach to the static spherically symmetric solutions of Einstein equations is
based on a careful physical analysis of radial gauge conditions. It brings us
to a two parameter family of relativistic stars without stiff functional
dependence between the stelar radius and stelar mass.
  As a result, a point particle idealization -- a limiting case of bodies with
finite dimension, becomes possible in GR, much like in Newtonian gravity. We
devote this article to detailed mathematical study of this limit.


title: Microarcsecond Astrometry using the SKA

abstract:
  The sensitivity and versatility of SKA will provide microarcsec astrometric
precision and high quality milliarcsec-resolution images by simultaneously
detecting calibrator sources near the target source. To reach these goals, we
suggest that the long-baseline component of SKA contains at least 25% of the
total collecting area in a region between 1000 to 5000 km from the core SKA. We
also suggest a minimum of 60 elements in the long-baseline component of SKA to
provide the necessary (u-v) coverage. For simultaneous all-sky observations,
which provide absolute astrometric and geodetic parameters, we suggest using
ten independent subarrays each composed of at least six long-baseline elements
correlated with the core SKA. We discuss many anticipated SKA long-baseline
astrometric experiments: determination of distance, proper motion and orbital
motion of thousands of stellar objects; planetary motion detections; mass
determination of degenerate stars using their kinetics; calibration of the
universal distance scale from 10 pc to 10 Mpc; the core and inner-jet
interactions of AGN. With an increase by a factor of 10 in absolute astrometric
accuracy using simultaneous all sky observations, the fundamental quasar
reference frame can be defined to <10 microarcsec and tied to the solar-system
dynamic frame to this accuracy. Parameters associated with the earth rotation
and orientation, nutation, and geophysical parameters, can be accurately
monitored. Tests of fundamental physics include: solar and Jovian deflection
experiments, the sky frame accuracy needed to interpret the gravity
wave/pulsar-timing experiment, accurate monitoring of spacecraft orbits which
impacts solar system dynamics.


title:
Effects of the core radius of an isothermal ellipsoidal gravitational
  lens on the caustics and the critical curves

abstract:
  We study the effect of the core radius of an isothermal ellipsoidal
gravitational lens on the caustics and the critical curves. We derive an
analytic expression of the caustics for an isothermal ellipsoidal gravitational
lens via a sixth-order algebraic equation. Since the expression is too long, by
using another method we obtain a parametric representation of the critical
curves in order to show analytically that there exist three cases: There are
two curves for a small core radius, one for a quite large one, and no curves
appear for an extremely large one, though the latter two cases are not
realistic. The caustics are represented also by the same parameter.


title: Inversion formula for determining parameters of an astrometric binary

abstract:
  It is believed that some numerical technique must be employed for the
determination of the system parameters of a visual binary or a star with a
planet because the relevant equations are not only highly nonlinear but also
transcendental owing to the Kepler's equation. Such a common sense, however, is
not true; we discover an analytic inversion formula, in which the original
orbital parameters are expressed as elementary functions of the observable
quantities such as the location of four observed points and the time interval
between these points. The key thing is that we use the time interval but not
the time of each observation in order to avoid treating the Kepler's equation.
The present formula can be applied even in cases where the observations cover a
short arc of the orbit during less than one period. Thus the formula will be
useful in the future astrometric missions such as SIM, GAIA and JASMINE.


title: VLBI detections of a source weaker than 100 mJy at 86 GHz

abstract:
  We use a new phase-calibration strategy to calibrate the phase of 86 GHz VLBI
observations of the FR I radio galaxy NGC 4261. Instead of switching between a
calibrator source and the target source, the target was observed while rapidly
switching between the target frequency and a lower reference frequency.
Self-calibration at the reference frequency yielded phase corrections which
were multiplied with the frequency ratio and applied to the target frequency
visibilities. The resulting detection of NGC 4261 is, to our knowledge, the
first of NGC 4261 with 86 GHz VLBI, and it is also the weakest source so far
detected with VLBI at that frequency.


title: Origin of the Blueshift in Signals from Pioneer 10 and 11

abstract:
  A previous paper [1] introduced a quantum-mechanical theory of gravity, and
showed it agrees with the standard experimental tests of general relativity.
Doppler tracking signals returned by the Pioneer 10 and 11 space probes offer
an additional test. Analysis by Anderson, Laing, Lau, Liu, Neito and Turyshev
[2] finds a persistent blueshift, equivalent to an extra acceleration of the
probes toward the Sun. While unexplained by general relativity or prevailing
cosmology, it's shown this effect is predicted by the quantum-mechanical
alternative.


title: A 2D analysis of percolation and filamentarity in the SDSS DR1

abstract:
  We have used the Largest Cluster Statistics and the Average Filamentarity to
quantify respectively the connectivity and the shapes of the patterns seen in
the galaxy distribution in two volume limited subsamples extracted from the
equatorial strips of the Sloan Digital Sky Survey (SDSS) Data Release One
(DR1). The data was projected onto the equatorial plane and analyzed in two
dimensions (2D). Comparing the results with Poisson point distributions at
various levels of smoothing we find evidence for a network like topology with
filaments being the dominant patterns in the galaxy distribution. With
increasing smoothing, a transition from many individual filamentary structures
to an interconnected network is found to occur at a filling factor 0.5-0.6. We
have tested the possibility that the connectivity and the morphology of the
patterns in the galaxy distribution may be luminosity dependent and find
significant evidence for a luminosity-morphology relation, the brighter
galaxies exhibiting lowers levels of connectivity and filamentarity compared to
the fainter ones. Using a statistical technique, Shuffle, we show that the
filamentarity in both the SDSS strips is statistically significant up to 80
Mpc/h but not beyond. Larger filaments, though identified, are not
statistically significant. Our findings reaffirm earlier work establishing the
filaments to be the largest known statistically significant coherent structures
in the universe.


title: Quiescent X-ray emission from an evolved brown dwarf ?

abstract:
  I report on the X-ray detection of Gl569Bab. During a 25ksec Chandra
observation the binary brown dwarf is for the first time spatially separated in
X-rays from the flare star primary Gl569A. Companionship to Gl569A constrains
the age of the brown dwarf pair to ~300-800 Myr. The observation presented here
is only the second X-ray detection of an evolved brown dwarf. About half of the
observing time is dominated by a large flare on Gl569Bab, the remainder is
characterized by weak and non-variable emission just above the detection limit.
This emission -- if not related to the afterglow of the flare -- represents the
first detection of a quiescent corona on a brown dwarf, representing an
important piece in the puzzle of dynamos in the sub-stellar regime.


title:
Comparing the temperatures of galaxy clusters from hydro-N-body
  simulations to Chandra and XMM-Newton observations

abstract:
  Theoretical studies of the physical processes in clusters of galaxies are
mainly based on the results of numerical simulations, which in turn are often
directly compared to X-ray observations. Although trivial in principle, these
comparisons are not always simple. We show that the projected spectroscopic
temperature of clusters obtained from X-ray observations is always lower than
the emission-weighed temperature. This bias is related to the fact that the
emission-weighted temperature does not reflect the actual spectral properties
of the observed source. This has implications for the study of thermal
structures in clusters, especially when strong temperature gradients, like
shock fronts, are present. In real observations shock fronts appear much weaker
than what is predicted by emission-weighted temperature maps.
  We propose a new formula, the spectroscopic-like temperature function that
better approximates the spectroscopic temperature, making simulations more
directly comparable to observations


title: Collective behavior in nuclear interactions and shower development

abstract:
  The mechanism of hadronic interactions at very high energies is still
unclear. Available accelerator data constrain weakly the forward rapidity
region which determines the development of atmospheric showers. This ignorance
is one of the main sources of uncertainty in the determination of the energy
and composition of the primary in hadron-induced atmospheric showers. In this
paper we examine the effect on the shower development of two kinds of
collective effects in high-energy hadronic interactions which modify the
production of secondary particles. The first mechanism, modeled as string
fusion, affects strongly the central rapidity region but only slightly the
forward region and is shown to have very little effect on the shower
development. The second mechanism implies a very strong stopping; it affects
modestly the profile of shower maximum but broadens considerably the number
distribution of muons at ground. For the latter mechanism, the development of
air showers is faster mimicking a heavier projectile. On the other hand, the
number of muons at ground is lowered, resembling a shower generated by a
lighter primary.


title: A concise review of the Iranian calendar

abstract:
  We present a general description of the Iranian calendar and Nowruz, which
starts at the precise instant when the Sun coincides with the vernal equinox.
Although the paper aims at the basic astronomical elements of the calendar,
historical aspects are not ignored.
  Using the ephemeris provided by the French Institut de Mecanique Celeste et
de Calcul des Ephemerides (IMCCE) for the period A.D. -4000 to +2500, we
discuss the various definitions of the year and show that the Iranian calendar
is based upon the vernal-equinox year and not on the ``tropical year'' of
365.2422 days formulated by researchers in the field of celestial mechanics.
  Neglecting the short-term fluctuations, the mean length of the Iranian year
at the present epoch is 365.2424 solar days, corresponding to the mean interval
between two successive passages of the Sun through the vernal equinox.
  There is now a widely spread confusion between the "tropical" and
vernal-equinox years, leading to the erroneous value of 365.2422 days often
given for the mean interval between two successive passages of the Sun through
the vernal equinox.
  We also analyze the intercalation system of the Iranian calendar, which is
based on a 33-year cycle, and point out the astronomical foundation of this
cycle created by the famous Iranian mathematician, astronomer, and poet Omar
Khayyam.


title: The Baryonic Tully-Fisher relation revisited

abstract:
  The Baryonic Tully-Fisher relation (BTF) can be substantially improved when
considering that the galactic baryonic mass is likely to consist not only from
the detected baryons, stars and gas, but also from a dark baryonic component
proportional to the HI gas. The BTF relation is optimally improved when the HI
mass is multiplied by a factor of about 3, but larger factors up to 11-16 still
improve the fit over the original one using only the detected baryons. The
strength of this improved relation is quantified with up-to-date statistical
tests such as the Akaike Information Criterion or the Bayesian Information
Criterion. In particular they allow to show that supposing a variable
$M_\star/L$ ratio instead is much less significant. This result reinforces the
suggestion made in several recent works that mass within galactic disks must be
a multiple of the HI mass, and that galactic disks are substantially, but not
necessarily fully, self-gravitating.


title: The orientation parameters and rotation curves of 15 spiral galaxies

abstract:
  We analyzed ionized gas motion and disk orientation parameters for 15 spiral
galaxies. Their velocity fields were measured with the H-alpha emission line by
using the Fabry-Perot interferometer at the 6m telescope of SAO RAS. Special
attention is paid to the problem of estimating the position angle of the major
axis (PA_0) and the inclination (i) of a disk, which strongly affect the
derived circular rotation velocity. We discuss and compare different methods of
obtaining these parameters from kinematic and photometric observations, taking
into account the presence of regular velocity (brightness) perturbations caused
by spiral density waves. It is shown that the commonly used method of tilted
rings may lead to systematic errors in the estimation of orientation parameters
(and hence of circular velocity) being applied to galaxies with an ordered
spiral structure. Instead we recommend using an assumption of constancy of i
and PA_0 along a radius, to estimate these parameters. For each galaxy of our
sample we present monochromatic H-alpha- and continuum maps, velocity fields of
ionized gas, and the mean rotation curves in the frame of a model of pure
circular gas motion. Significant deviations from circular motion with
amplitudes of several tens of km/s (or higher) are found in almost all
galaxies. The character and possible nature of the non-circular motion are
briefly discussed.


title: Extragalactic science at very high spectral resolution

abstract:
  I briefly mention a few possible applications of very high spectral
resolution spectroscopy with CRIRES to the study of nearby galaxies. This
includes the fields of AGN, dynamically cold systems, super stellar and
emission line clusters, and a more speculative program on the measurement of
gravitational redshifts.


title: The Bologna Complete Sample of Nearby Radio Sources

abstract:
  We present a new, complete, sample of 95 radio sources selected from the B2
and 3CR catalogues, with z < 0.1. Since no selection effect on the core radio
power, jet velocity, or source orientation is present, this sample is well
suited for statistical studies. In this first paper we present the
observational status of all sources on the parsec (mas) and kiloparsec (arcsec)
scale; we give new parsec-scale data for 28 sources and discuss their
parsec-scale properties. Combining these data with those in the literature,
information on the parsec-scale morphology is available for a total of 53 radio
sources with different radio power and kpc-scale morphology. We investigate
their properties. We find a dramatically higher fraction of two-sided sources
in comparison to previous flux limited VLBI surveys.


title: Bar-driven fueling of galactic nuclei: a 2D view

abstract:
  I discuss evidences for bar-driven gas fueling in the central regions of
galaxies, focusing on scales down to about 10 pc. I thus mention the building
of inner disks, and the link with resonances, as well as the corresponding
kinematic signatures such as sigma-drops and counter-rotating nuclear disks as
probed via integral-field spectroscopy.


title: A puzzling event during the X-ray emission of the binary system GX 1+4

abstract:
  We report on a long X-ray observation of the slow-rotating binary pulsar GX
1+4. BeppoSAX observed, in the 0.1-200 keV energy range, an event in which the
source flux dropped for almost a day, and then recovered. During this event
only the high-energy emission was found to be pulsed and the pulsations were
shifted in phase of ~0.2 . The spectrum during the event was well fitted by a
Compton-reflection model. A broad iron line at ~6.55 keV was present outside of
the event, where instead two narrow emission lines at ~6.47 keV and ~7.05 keV
were detected. The pulse profile was highly variable as a function of both
energy and time. We interpret this low-flux event as an occultation of the
direct X-ray emission, due to the increase of a torus-like accretion disk; we
then discuss similarities between this source and the recently discovered
highly absorbed INTEGRAL sources.


title:
XMM-Newton observation of the most X-ray-luminous galaxy cluster RX
  J1347.5-1145

abstract:
  We report on an XMM-Newton observation of RX J1347.5-1145 (z=0.451), the most
luminous X-ray cluster of galaxies currently known, with a luminosity L_X = 6.0
\pm 0.1 \times 10^45 erg/s in the [2-10] keV energy band. We present the first
temperature map of this cluster, which shows a complex structure. It identifies
the cool core and a hot region at radii 50-200 kpc to south-east of the main
X-ray peak, at a position consistent with the subclump seen in the X-ray image.
This structure is probably an indication of a submerger event. Excluding the
data of the south-east quadrant, the cluster appears relatively relaxed and we
estimate a total mass within 1.7 Mpc of 2.0 \pm 0.4 \times 10^15 M_sun. We find
that the overall temperature of the cluster is kT=10.0 \pm 0.3 keV. The
temperature profile shows a decline in the outer regios and a drop in the
centre, indicating the presence of a cooling core which can be modelled by a
cooling flow model with a minimum temperature ~2 keV and a very high mass
accretion rate, \dot{M} ~ 1900 M_sun/yr. We compare our results with previous
observations from ROSAT, ASCA and Chandra.