title: Results from the ULTRA experiment in the framework of the EUSO project

abstract:
  The detection of Cerenkov light from EAS in a delayed coincidence with
fluorescence light gives a strong signature to discriminate protons and
neutrinos in cosmic rays. For this purpose, the ULTRA experiment has been
designed with 2 detectors: a small EAS array (ETscope) and an UV optical device
including wide field (Belenos) and narrow field (UVscope) Cerenkov light
detectors. The array measures the shower size and the arrival direction of the
incoming EAS, while the UV devices, pointing both to zenith and nadir, are used
to determine the amount of direct and diffused coincident Cerenkov light. This
information, provided for different diffusing surfaces, will be used to verify
the possibility of detecting from Space the Cerenkov light produced by UHECRs
with the EUSO experiment, on board the ISS.


title:
Near-Infrared and Optical Studies of the fast nova V4643 Sgr (Nova
  Sagittarii 2001)

abstract:
  V4643 Sagittarii or Nova Sagittarii 2001 was discovered in outburst at 7.7
mag. on 2001 February 24. Here, we present near-infrared results of this fast
classical nova obtained in the early decline phase in 2001 March followed by
optical observations about one month later. Subsequently we also present
near-infrared spectra taken later in the nova's evolution, about four months
after the outburst, when V4643 Sgr had entered the coronal phase. The spectra
in the early decline phase are dominated by emission lines of the HI Brackett
series and also the Paschen beta and gamma lines. We study the cause of the
excitation of the the OI line at 1.128 micron and discuss the variation in its
strength with time after outburst. We discuss the role of optical depth effects
on the observed strengths of the hydrogen Brackett and Paschen lines and
discuss possible reasons for the puzzling behavior of the Br gamma line
strength and whether it is correlated with the OI 1.128 micron line behavior.
An optical spectrum is presented which shows that HeII lines are the most
prominent features - after HI - to be seen in early 2001 April. We present and
also discuss spectra taken in 2001 June and August which prominently show
coronal lines of [Si VI] and [Si VII] at 1.9641 micron and 2.4807 micron
respectively.


title: Detecting filaments in the ultra-high energy cosmic ray distribution

abstract:
  We propose and test new statistical tools to study the distribution of cosmic
rays based on the use of the Minimal Spanning Tree. The method described is
particularly sensitive to filamentary structures, as those expected to arise
from strong sources of charged cosmic rays which get deflected by intervening
magnetic fields. We also test the method with data available from the AGASA and
SUGAR surface detector arrays.


title: Crystalline silicates as a probe of disk formation history

abstract:
  We present a new perspective on the crystallinity of dust in protoplanetary
disks. The dominant crystallization by thermal annealing happens in the very
early phases of disk formation and evolution. Both the disk properties and the
level of crystallinity are thereby directly linked to the properties of the
molecular cloud core from which the star+disk system was formed. We show that,
under the assumption of single star formation, rapidly rotating clouds produce
disks which, after the main infall phase (i.e. in the optically revealed class
II phase), are rather massive and have a high accretion rate but low
crystallinity. Slowly rotating clouds, on the other hand, produce less massive
disks with lower accretion rate, but high levels of crystallinity. Cloud
fragmentation and the formation of multiple stars complicates the problem and
necessitates further study. The underlying physics of the model is
insufficiently understood to provide the precise relationship between
crystallinity, disk mass and accretion rate. But the fact that with `standard'
input physics the model produces disks which, in comparison to observations,
appear to have either too high levels of crystallinity or too high disk masses,
demonstrates that the comparison of these models to observations can place
strong contraints on the disk physics. The question to ask is not why some
sources are so crystalline, but why some other sources have such a low level of
crystallinity.


title:
The neutrino mass bound from WMAP-3, the baryon acoustic peak, the SNLS
  supernovae and the Lyman-alpha forest

abstract:
  We have studied bounds on the neutrino mass using new data from the WMAP 3
year data, the Sloan Digital Sky Survey measurement of the baryon acoustic
peak, the Type Ia supernovae from SNLS, and the Lyman-alpha forest. We find
that even in the most general models with a running spectral index where the
number of neutrinos and the dark energy equation of state are allowed to vary,
the 95% C.L. bound on the sum of neutrino masses is sum m_nu < 0.62 eV (95%
C.L.), a bound which we believe to be robust. In the more often used
constrained analysis with N_nu =3, w = -1, and alpha_s = 0, we find a bound of
0.48 eV without using the Lyman-alpha data. If Lyman-alpha data is used, the
bound shrinks to \sum m_nu < 0.2-0.4 eV (95% C.L.), depending strongly on the
Lyman-alpha analysis used.


title: The Quintom Model of Dark Energy

abstract:
  In this paper I give a brief review on the recently proposed new scenario of
dark energy model dubbed $Quintom$. Quintom describes the dynamical dark energy
models where the equation of state getting across the cosmological constant
boundary during evolutions. I discuss some aspects on the quintom model
buildings and the observational consequences.


title:
Do magnetic fields contribute to the dynamical stability of the
  secondaries of CVs against mass transfer?

abstract:
  We show the presence of CVs with orbital periods in the range 3.5-7 h and
mass ratios q=M2/M1 above the critical values for dynamically stable mass
transfer. We explore whether the magnetic fields produced in the secondaries
alter the theoretical mass ratio limits allowing dynamical stability. Since
magnetic fields change the specific heats and the polytropic exponent gamma of
the gas in the convective envelope, the mass-radius adiabatic exponent xi_ad
also changes. We find that turbulent magnetic fields can produce 10% less
restrictive critical q-profiles while large-scale toroidal and poloidal fields
have smaller effects. Thus, magnetic fields alone do not account for the
stability of all the anomalous CVs. However, we found that the small variations
of xi_ad induced by solar-type magnetic cycles explain the amplitudes of the
cyclic accretion luminosity variations shown by several CVs.


title: VLBA images of High Frequency Peakers

abstract:
  We propose a morphological classification based on the parsec scale structure
of fifty-one High Frequency Peakers (HFPs) from the ``bright'' HFP sample. VLBA
images at two adjacent frequencies (chosen among 8.4, 15.3, 22.2 and 43.2 GHz)
have been used to investigate the morphological properties of the HFPs in the
optically thin part of their spectrum. We confirm that there is quite a clear
distinction between the pc-scale radio structure of galaxies and quasars: the
78% of the galaxies show a ``Double/Triple'' morphology, typical of Compact
Symmetric Objects (CSOs), while the 87% of the quasars are characterised by
Core-Jet or unresolved structure. This suggests that most HFP candidates
identified with quasars are likely blazar objects in which a flaring
self-absorbed component at the jet base was outshining the remainder of the
source at the time of the selection based on the spectral shape. Among the
sources classified as CSOs or candidates it is possible to find extremely young
radio sources with ages of about 100 years or even less.


title:
A weak acceleration effect due to residual gravity in a multiply
  connected universe

abstract:
  Could cosmic topology imply dark energy? We use a weak field (Newtonian)
approximation of gravity and consider the gravitational effect from distant,
multiple copies of a large, collapsed (virialised) object today (i.e. a massive
galaxy cluster), taking into account the finite propagation speed of gravity,
in a flat, multiply connected universe, and assume that due to a prior epoch of
fast expansion (e.g. inflation), the gravitational effect of the distant copies
is felt locally, from beyond the naively calculated horizon. We find that for a
universe with a $T^1xR^2$ spatial section, the residual Newtonian gravitational
force (to first order) provides an anisotropic effect that repels test
particles from the cluster in the compact direction, in a way algebraically
similar to that of dark energy. For a typical test object at comoving distance
$\chi$ from the nearest dense nodes of the cosmic web of density perturbations,
the pressure-to-density ratio $w$ of the equation of state in an FLRW universe,
is w \sim - (\chi/L)^3, where $L$ is the size of the fundamental domain, i.e.
of the universe. Clearly, |w|<<1. For a T^3 spatial section of exactly equal
fundamental lengths, the effect cancels to zero. For a T^3 spatial section of
unequal fundamental lengths, the acceleration effect is anisotropic in the
sense that it will *tend to equalise the three fundamental lengths*. Provided
that at least a modest amount of inflation occurred in the early Universe, and
given some other conditions, multiple connectedness does generate an effect
similar to that of dark energy, but the amplitude of the effect at the present
epoch is too small to explain the observed dark energy density and its
anisotropy makes it an unrealistic candidate for the observed dark energy.


abstract:
  The Boston University-Five College Radio Astronomy Observatory Galactic Ring
Survey is a new survey of Galactic 13CO (1-0) emission. The survey used the
SEQUOIA multi pixel array on the Five College Radio Astronomy Observatory 14 m
telescope to cover a longitude range of l = 18 deg-55.7 deg and a latitude
range of |b| < 1 deg, a total of 75.4 square degrees. Using both
position-switching and On-The-Fly mapping modes, we achieved an angular
sampling of 22 arcsec, better than half of the telescope's 46 arcsec angular
resolution. The survey's velocity coverage is -5 to 135 km/s for Galactic
longitudes l <= 40 deg and -5 to 85 km/s for Galactic longitudes l > 40 deg. At
the velocity resolution of 0.21 km/s, the typical rms sensitivity is
sigma(TA*)~0.13 K. The survey comprises a total of 1,993,522 spectra. We show
integrated intensity images (zeroth moment maps), channel maps,
position-velocity diagrams, and an average spectrum of the completed survey
dataset. We also discuss the telescope and instrumental parameters, the
observing modes, the data reduction processes, and the emission and noise
characteristics of the dataset. The Galactic Ring Survey data are available to
the community at www.bu.edu/galacticring or in DVD form by request.


title: Solar system constraints on multi-field theories of modified dynamics

abstract:
  Any viable theory of modified Newtonian dynamcs (MOND) as modified gravity is
likely to require fields in addition to the usual tensor field of General
Relativity. For such theories the MOND phenomenology emerges from an effective
fifth force probably associated with a scalar field. Here I consider the
constraints imposed upon such theories by solar system phenomenology, primarily
by the absence of significant deviations from inverse square attraction in the
inner solar system as well as detectable local preferred frame effects. The
current examples of multi-field theories can be constructed to satisfy these
constraints and such theories lead inevitably to an anomalous non
inverse-square force in the outer solar system.


title: Jet Speeds in Wide Angle Tailed Radio Galaxies

abstract:
  We present a sample of 30 wide angle tailed radio galaxies (WATs) that we use
to constrain the jet speeds in these sources. We measure the distribution of
jet-sidedness ratios for the sample, and assuming that the jets are beamed, jet
speeds in the range (0.3-0.7)c are obtained. Whilst the core prominence of the
sample, which ought to be a reliable indicator of beaming, shows little
correlation with the jet-sidedness, we argue that due to the peculiar nature of
WATs core-prominence is unlikely to be a good indicator of beaming in these
sources. We further show that if the jets are fast and light, then the galaxy
speeds required to bend jets into C-shapes such as those seen in 0647+693 are
reasonable for a galaxy in a merging or recently merged cluster.


title: Evidence for a Supernova Associated with the X-ray Flash 020903

abstract:
  We present ground-based and Hubble Space Telescope optical observations of
the X-ray flash (XRF) 020903, covering 300 days. The afterglow showed a very
rapid rise in the first day, followed by a relatively slow decay in the next
few days. There was a clear bump in the light curve after ~25 days, accompanied
by a drastic change in the spectral energy distribution. The light curve and
the spectral energy distribution are naturally interpreted as the emergence --
and subsequent decay -- of a supernova (SN), similar to SN 1998bw. At peak
luminosity, the SN is estimated to be 0.8 +/- 0.1 mag fainter than SN1998bw.
This argues in favor of the existence of a supernova associated with this X-ray
flash. A spectrum obtained 35 days after the burst shows emission lines from
the host galaxy. We use this spectrum to put an upper limit on the oxygen
abundance of the host at [O/H] < -0.6 dex. We also discuss a possible trend
between the softness of several bursts and the early behavior of the optical
afterglow, in the sense that XRFs and X-ray rich GRBs seem to have a plateau
phase or even a rising light curve. This can be naturally explained in models
where XRFs are similar to GRBs but seen off the jet axis.


title:
Gravitational Radiation from Ultra High Energy Cosmic Rays in Models
  with Large Extra Dimensions

abstract:
  The effects of classical gravitational radiation in models with large extra
dimensions are investigated for ultra high energy cosmic rays (CRs). The cross
sections are implemented into a simulation package (SENECA) for high energy
hadron induced CR air showers. We predict that gravitational radiation from
quasi-elastic scattering could be observed at incident CR energies above $10^9$
GeV for a setting with more than two extra dimensions. It is further shown that
this gravitational energy loss can alter the energy reconstruction for CR
energies $E_{\rm CR}\ge 5\cdot 10^9$ GeV.


title:
The influence of radio-galaxy activity on X-ray absorption lines from
  the intracluster medium

abstract:
  We present an investigation of the X-ray absorption features predicted by
hydrodynamic simulations of radio galaxies interacting with the intracluster
medium (ICM) of their host galaxy clusters. We show how these absorption lines
can be used as a new diagnostic for the radio-galaxy/ICM interactions. Such
interactions have been observed in numerous systems by ROSAT, CHANDRA and
XMM-NEWTON, and understanding them has implications for AGN feedback and galaxy
formation. Starting from the hydrodynamic simulations of Reynolds, Heinz &
Begelman, we calculate the properties of the highly ionized iron and oxygen
lines (seen in absorption against the central active galactic nucleus; AGN),
predicting line shapes, equivalent widths, column densities and velocity
shifts. The main effect of the jet on the absorption lines is a reduction of
the line strength from that of the quiescent ICM and the introduction of some
velocity structure in the line profile. We investigate whether these features
are detectable with current as well as future high-resolution X-ray
spectrometers. We conclude that the CHANDRA transmission gratings have
insufficient sensitivity to detect these features with high significance, and
certainly would not allow a study of the dynamics of the interaction via
absorption signatures. CONSTELLATION-X, on the other hand, will allow superb
constraints to be derived. We can also use this analysis to assess the idea
that radio-galaxy induced ICM outflows give rise to the resonant oxygen X-ray
absorption lines that have been claimed as evidence for the warm-hot
intergalactic medium (WHIM). We show that these detached, high-velocity oxygen
absorption lines cannot result from a radio-galaxy/ICM interaction, thereby
strengthening the WHIM interpretation.


title:
Unified Model for Inflation and Dark Energy with Planck-Scale
  Pseudo-Goldstone Bosons

abstract:
  We present a model with a complex and a real scalar fields and a potential
whose symmetry is explicitly broken by Planck-scale physics. For exponentially
small breaking, the model accounts for the period of inflation in the early
universe and for the period of acceleration of the late universe.


title:
HST/STIS Spectroscopy and Modeling of the Long Term Cooling of WZ
  Sagittae following the July 2001 Outburst

abstract:
  We present the last HST/STIS E140M FUV spectrum (1150-1725A) of the dwarf
nova (DN) WZ Sge, obtained in July 2004, 3 years following the early
superoutburst of July 2001. Single white dwarf (WD) synthetic spectral fits
(log{g}=8.5) to the data indicate that the WD has a temperature T~15,000K,
about ~1500K above its quiescent temperature and it is still showing the effect
of the outburst. Taking into account temperature estimates of the earlier phase
of the cooling, we model the cooling curve of WZ Sge, over a period of 3 years,
using a stellar evolution code including accretion and the effects of
compressional heating. Assuming that compressional heating alone is the source
of the energy released during the cooling phase, we find that (1) the mass of
the white dwarf must be quite large (~1.0 Msun); and (2) the mass accretion
rate must have a time-averaged (over 52 days of outburst) value of the order of
1.E-8 Msun/yr or larger. The outburst mass accretion rate derived from these
compressional heating models is larger than the rates estimated from optical
observations and from a FUV spectral fit by up to one order of magnitude. This
implies that during the cooling phase the energy released by the WD is not due
to compressional heating alone.


title: Distribution of the Extinction and Star Formation in NGC 1569

abstract:
  We investigate spatial the distribution of the intrinsic extinction in the
starburst dwarf galaxy NGC1569 creating an extinction map of the whole galaxy
derived from the Halpha/Hbeta emission line ratio. We differentiate the
extinction in the HII regions from the extinction of the diffuse gas. The
intrinsic extinction shows considerable variations over the plane of the
galaxy, from negligible extinction up to highest values of A(V)=0.8mag. The
extinction map shows small scale clumpy structures possibly due to a clumpy
dust distribution. We also identify in this map a shell structure, for which we
establish a causal relation with the expanding gas structure produced by the
stellar winds coming from the Super Star Clusters (SSC) in the center of the
galaxy. The comparison of the spatial profiles of the extinction, dust and
gaseous emissions crossing the border of the shell shows a layered structure;
the peak of this Halpha distribution lying closest to the SSC A, followed
outwards by the peak of the extinction and at a still larger distances by the
bulk of the atomic gas. We suggest that the extinction shell has been produced
by the SSCs and that it can be explained by the accumulation of dust at the
border of this ionized gas structure.


title: Analysis of IUE spectra of helium-rich white dwarf stars

abstract:
  We studied the class of DB white dwarf stars, using re-calibrated UV spectra
for thirty four DBs obtained with the IUE satellite. By comparing the observed
energy distributions with model atmospheres, we simultaneously determine
spectroscopic distances (d), effective temperature (Teff), and surface
gravities (log g). Using parallax measurements and previous determinations of
Teff and log g from optical spectra, we can study whether the atmospheres of
eleven DB stars are consistent with pure He or have a small amount of H
contamination. We also report on our observations of seventeen stars with Teff
close to the DB instability strip through time series photometry and found them
to be non variable within our detection limits.


title: Polarimetry and the Envelopes of Magellanic B[e] Supergiants

abstract:
  We discuss the nature of the circumstellar envelopes around the B[e]
supergiants (B[e]SG) in the Magellanic Clouds (MC). Contrary to those in the
Galaxy, the MC B[e]SG have a well defined luminosity and can be considered
members of a well defined class. We discuss spectroscopy and optical broadband
polarimetry and spectropolarimetry data. These data show for the first time
detailed changes in the polarization across several spectral features.
  We show that the envelopes of the B[e]SG are generally variable. Broadband
polarimetry data show that the envelopes are definitely non-spherically
symmetric and large non-axisymmetric ejections may occur. In addition to that,
spectropolarimetry is coming of age as a tool to study the B[e]SG envelope
structure.


title: AGN-controlled cooling in elliptical galaxies

abstract:
  A long-standing problem for models of galaxy formation has been the mismatch
between the predicted shape of the mass function of dark matter halos and the
observed shape of the luminosity function of galaxies. The number of massive
halos is predicted to decrease as a power law (N proportional to M^-2) out to
very large masses, while the galaxy luminosity function cuts off exponentially
at luminosities above L*. This implies that the efficiency with which gas cools
onto massive systems is lower than expected. This letter investigates the role
of radio-loud active galactic nuclei (AGN) in continually re-heating the
cooling gas. By combining two observational results, the time-averaged energy
output associated with recurrent radio source activity is determined, as a
function of the black hole mass of the host galaxy: H = 10^21.4 (M_BH /
M_sun)^1.6 W. It is shown that for massive elliptical galaxies this
radio-source heating balances the radiative energy losses from the hot gas
surrounding the galaxy. The recurrent radio-loud AGN activity may therefore
provide a self-regulating feedback mechanism capable of controlling the rate of
growth of galaxies.


title:
Probing the IGM/Galaxy Connection Toward PKS0405-123 III: The Galaxy
  Survey and Correlations with OVI Absorbers

abstract:
  We present a galaxy survey of the field surrounding PKS0405-123 performed
with the WFCCD spectrometer at Las Campanas Observatory. The survey is
comprised of two datasets: (1) a greater than 95% complete survey to R = 20 of
the field centered on PKS0405-123 with 10' radius (L~0.1 L_* and radius of 1Mpc
at z=0.1); and (2) a set of four discontiguous (i.e. non-overlapping), flanking
fields covering ~1 square degree area with completeness ~90% to R=19.5mag. With
these datasets, one can examine the local and large-scale galactic environment
of the absorption systems identified toward PKS0405-123. In this paper, we
focus on the OVI systems analyzed in Paper I. The results suggest that this gas
arises in a diverse set of galactic environments including the halos of
individual galaxies, galaxy groups, filamentary-like structures, and also
regions devoid of luminous galaxies. In this small sample, there are no obvious
trends between galactic environment and the physical properties of the gas.
Furthermore, we find similar results for a set of absorption systems with
comparable N(HI) but no detectable metal-lines. The observations indicate that
metals are distributed throughout a wide range of environments in the local
universe. Future papers in this series will address the distribution of
galactic environments associated with metal-line systems and the Lya forest
based on data for over 10 additional fields. All of the data presented in this
paper is made public at a dedicated web site.


title: Origin of Structures in Wolf-Rayet Winds: FUSE Observations of WR 135

abstract:
  We report the detection with FUSE of strong, highly blue-shifted absorption
features appearing in the absorption troughs of practically all major P Cygni
profiles in the presumably single Wolf-Rayet star WR135. These features also
appear in the shock-sensitive OVI 1032/38 \AA doublet, coincident both in time
and velocity space with the rest of the lower-ionization species. Choosing
between two alternative interpretations: large-scale, coherent structures vs.
localized, random shocks, we favor the latter. The absolute value of velocity,
as well as velocity dispersion in the shocked region, the density of the
shocked gas, and the time scales of the observed variability allow us to relate
the observed shocks to the incidence of numerous over-dense clumps (blobs) in
the wind of a hot, massive star.


title: The Depiction of Coronal Structure in White Light Images

abstract:
  The very sharp decrease of density with heliocentric distance makes imaging
of coronal density structures out to a few solar radii challenging. The radial
gradient in brightness can be reduced using numerous image processing
techniques, thus quantitative data are manipulated to provide qualitative
images. Introduced in this study is a new normalizing radial graded filter
(NRGF), a simple filter for removing the radial gradient to reveal coronal
structure. Applied to polarized brightness observations of the corona, the NRGF
produces images which are striking in their detail. Total brightness white
light images include contributions from the F corona, stray light and other
instrumental contributions which need to be removed as effectively as possible
to properly reveal the electron corona structure. A new procedure for
subtracting this background from LASCO C2 white light total brightness images
is introduced. The background is created from the unpolarized component of
total brightness images and is found to be remarkably time-invariant, remaining
virtually unchanged over the solar cycle. By direct comparison with polarized
brightness data, we show that the new background subtracting procedure is
superior in depicting coronal structure accurately, particularly when used in
conjunction with the NRGF. The effectiveness of the procedures is demonstrated
on a series of LASCO C2 observations of a coronal mass ejection (CME).


title: Simultaneous X-ray/optical observations of GX 9+9 (4U 1728-16)

abstract:
  We report on the results of the first simultaneous X-ray (RXTE) and optical
(SAAO) observations of the luminous low mass X-ray binary (LMXB) GX 9+9 in 1999
August. The high-speed optical photometry revealed an orbital period of 4.1958
hr and confirmed previous observations, but with greater precision. No X-ray
modulation was found at the orbital period. On shorter timescales, a possible
1.4-hr variability was found in the optical light curves which might be related
to the mHz quasi-periodic oscillations seen in other LMXBs. We do not find any
significant X-ray/optical correlation in the light curves. In X-rays, the
colour-colour diagram and hardness-intensity diagram indicate that the source
shows characteristics of an atoll source in the upper banana state, with a
correlation between intensity and spectral hardness. Time-resolved X-ray
spectroscopy suggests that two-component spectral models give a reasonable fit
to the X-ray emission. Such models consist of a blackbody component which can
be interpreted as the emission from an optically thick accretion disc or an
optically thick boundary layer, and a hard Comptonized component for an
extended corona.


title:
The Impact of Sunspots on the Interpretation of Coronal Observations of
  the O VI Doublet

abstract:
  Due to their high intensity of emission in the O VI 1031.9 and 1037.6A lines,
even small sunspots on the solar disk can strongly influence the intensity of
the radiative scattering component of O VI lines in the corona. Observations of
O VI disk spectra show a 1032/1038 line intensity ratio of >2.6 in a sunspot
compared to quiet disk values of 2. The enhancement of the 1032 line in
comparison to the 1038 is likely due to interaction between molecular hydrogen
emission from the sunspot and the chromospheric O5+. Modeling shows that a
contribution from sunspots increases the coronal O VI 1032/1038 intensity ratio
to values considerably higher than those achieved with a quiet disk or coronal
hole spectrum. Therefore a re-examination of flow velocities derived from
UVCS/SOHO streamer observations must be made. This modeling demonstrates that
the inclusion of sunspots, when present, may lead to non-zero outflow
velocities at lower heights in streamer cores in contrast to some existing
model results.


title: Theory of cosmic ray production in the supernova remnant RX J1713.7-3946

abstract:
  A nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova
remnants (SNRs) is employed to investigate the properties of SNR RX
J1713.7-3946. Observations of the nonthermal radio and X-ray emission spectra
as well as the H.E.S.S. measurements of the very high energy gamma-ray emission
are used to constrain the astronomical and the particle acceleration parameters
of the system. Under the assumptions that RX J1713.7-3946 was a core collapse
supernova (SN) of type II/Ib with a massive progenitor, has an age of \approx
1600 yr and is at a distance of \approx 1 kpc, the theory gives indeed a
consistent description for all the existing observational data. Specifically it
is shown that an efficient production of nuclear CRs, leading to strong shock
modification, and a large downstream magnetic field strength B_d ~ 100 mkG can
reproduce in detail the observed synchrotron emission from radio to X-ray
frequencies together with the gamma-ray spectral characteristics as observed by
the H.E.S.S. telescopes. Small-scale filamentary structures observed in
nonthermal X-rays provide empirical confirmation for the field amplification
scenario which leads to a strong depression of the inverse Compton and
Bremsstrahlung fluxes. Going beyond that and using a semi-empirical relation
for young SNRs between the resulting CR pressure and the amplified magnetic
field energy upstream of the outer SN shock as well as a moderate upper bound
for the mechanical explosion energy, it is possible to also demonstrate the
actual need for a considerable shock modification in RX J1713.7-3946. It is
consistent with RX J1713.7-3946 being an efficient source of nuclear cosmic
rays.


title:
Gamma-Ray Luminosity Function of Blazars and the Cosmic Gamma-Ray
  Background: Evidence for the Luminosity Dependent Density Evolution

abstract:
  We present a comprehensive study for the gamma-ray luminosity function (GLF)
of blazars and their contribution to the extragalactic diffuse gamma-ray
background (EGRB). Radio and gamma-ray luminosity correlation is introduced to
take into account the radio detectability which is important for the blazar
identification. Previous studies considered only pure luminosity evolution
(PLE) or pure density evolution, but we introduce the luminosity dependent
density evolution (LDDE) model, which is favored from the evolution of X-ray
luminosity function (XLF) of AGNs. The model parameters are constrained by
likelihood analyses about the observed redshift and gamma-ray flux
distributions of the EGRET blazars. We find that the LDDE model gives a better
fit to the observed distributions than the PLE model, indicating that the LDDE
model is also appropriate for gamma-ray blazars, and that the jet activity is
universally correlated with the accretion history of AGNs. The normalization
between the GLF and XLF is consistent with the unified picture of AGNs, when
the beaming and a reasonable duty cycle of jet activity are taken into account.
We then find that only 25--50% of the EGRB can be explained by unresolved
blazars with the best-fit LDDE parameters. Unresolved blazars can account for
all the EGRB only with a steeper index of the faint-end slope of the GLF, which
is marginally consistent with the EGRET data but inconsistent with that of the
XLF. Therefore unresolved AGNs cannot be the dominant source of the EGRB,
unless there is a new population of gamma-ray emitting AGNs that evolves
differently from the XLF of AGNs. Predictions for the GLAST mission are made,
and we find that the best-fit LDDE model predicts about 3000 blazars in the
entire sky, which is considerably fewer than a previous estimate.


title:
Local Group Dwarf Galaxies and the Contribution of the First Stars to
  Reionization

abstract:
  The Local Group contains some dwarf galaxies that apparently formed all their
stars early, lost their gas to winds or ionization, and survive today as
``fossils'' from the epoch of reionization. This study presents new models of
these objects based on the hierarchical chemical evolution framework of
Tumlinson (2006). The model accurately reproduces the observed
luminosity-metallicity relation of fossil dwarf galaxies with minimal free
parameters. When calibrated to this relation, the models show that small dark
matter ``minihalos'' formed 2 - 8% of their baryonic mass into stars prior
during reionization. By tracking the chemical enrichment of these early halos
the models specify that metal-free first stars contributed approximately 5 - 10
% of the ionizing photons generated by these small halos and so did not
dominate reionization. Models that allow for larger relative contributions from
metal-free stars may not generate enough total ionizing photons for early
reionization. As significant star formation in early minihalos is a requirement
of many successful models for the IGM reionization, these models can be
considered to pass a key test of their validity. It appears we have as much to
learn about reionization from the universe at z = 0 as at z = 6.


title: Multi-colour optical monitoring of eight red blazars

abstract:
  We present the observational results of multi-colour optical monitoring of
eight red blazars from 2003 September to 2004 February. The aim of our
monitoring is to investigate the spectral variability as well as the flux
variations at short and long time scales. The observations were carried out
using the 1.0 m robotic telescope of Mt. Lemmon Optical Astronomy Observatory,
in Arizona, USA, the 0.6 m telescope of Sobaeksan Optical Astronomy Observatory
and the 1.8 m telescope of Bohyunsan Optical Astronomy Observatory, in the
Republic of Korea. During the observations, all sources show strong flux
variations with amplitudes of larger than 0.5 mag. Variations with amplitudes
of over 1 mag are found in four sources. Intraday variations with amplitudes
larger than 0.15 mag, and a rapid brightness increase with a rate of ~0.2 mag
per day in four days, are detected in S5 0716+71. We investigate the
relationship between the colour index and source brightness for each source. We
find that two out of three FSRQs tend to be redder when they are brighter, and,
conversely, all BL Lac objects tend to be bluer. In particular, we find a
significant anti-correlation between the V-I colour index and R magnitude for
3C 454.3. This implies that the spectrum became steeper when the source was
brighter, which is opposite to the common trend for blazars. In contrast,
significant positive correlations are found in 3C 66A, S5 0716+71, and BL Lac.
However, there are only very weak correlations for PKS 0735+17 and OJ 287. We
propose that the different relative contributions of the thermal versus
non-thermal radiation to the optical emission may be responsible for the
different trends of the colour index with brightness in FSRQs and BL Lac
objects.


title:
Superhumps Behavior during Normal Outbursts in ER UMa: Spectroscopy and
  Photometry

abstract:
  We have taken a 4-day spectroscopic observation and have been conducting a
13-day photometric study of the SU UMa-type dwarf nova, ER Ursae Majoris. The
mean $K$-amplitude for the emission lines is $54\pm 8$ km s$^{-1}$ and $\gamma$
velocity is 8$\pm 4$ km s$^{-1}$ from our spectroscopic results. A phase shift
of 0.22 is also obtained.
  Our photometric observation confirms superhumps in normal outbursts of ER UMa
and reconciles contradictory observational results obtained by different
authors. We find that superhumps possibly develop near each normal outburst
maximum and fade out before the next outburst maximum. If the observed humps
were not late superhumps but ordinary superhumps, much more theoretical works
should be done to explain the new phenomena.


title:
Analytical and numerical studies of fluid instabilities in relativistic
  jets

abstract:
  Relativistic outflows represent one of the best-suited tools to probe the
physics of AGN. Numerical modelling of internal structure of the relativistic
outflows on parsec scales provides important clues about the conditions and
dynamics of the material in the immediate vicinity of the central black holes
in AGN. We investigate possible causes of the structural patterns and
regularities observed in the parsec-scale jet of the well known quasar 3C 273.
We compare the model with the radio structure observed in 3C 273 on parsec
scales using very long baseline interferometry (VLBI) and constrain the basic
properties of the flow. Our results show that Kelvin-Helmholtz instabilities
are the most plausible mechanism to generate the observed structures.


title:
The cyclo-synchrotron process and particle heating through the
  absorption of photons

abstract:
  We propose a new approximation for the cyclo-synchrotron emissivity of a
single electron. In the second part of this work, we discuss a simple
application for our approximation, and investigate the heating of electrons
through the self-absorption process. Finally, we investigate the self-absorbed
part of the spectrum produced by a power-law population of electrons. In
comparison to earlier approximations, our formula provides a few significant
advantages. Integration of the emissivity over the whole frequency range,
starting from the proper minimal emitting frequency, gives the correct cooling
rate for any energy particle. Further, the spectrum of the emission is well
approximated over the whole frequency range, even for relatively low particle
energies (beta << 0.1), where most of the power is emitted in the first
harmonic. In order to test our continuous approximation, we compare it with a
recently derived approximation of the first ten harmonics. Finally, our formula
connects relatively smooth to the synchrotron emission at beta=0.9. We show
that the self-absorption is a very efficient heating mechanism for low energy
particles, independent of the shape of the particle distribution responsible
for the self-absorbed synchrotron emission. We find that the energy gains for
low energy particles are always higher than energy losses by cyclo-synchrotron
emission. We show also that the spectral index of the self-absorbed part of the
spectrum at very low frequencies differs significantly from the well known
standard relation I(nu) ~ nu^(5/2).


title: Celestial positions in radio and optical

abstract:
  We discuss the importance of the direct link between the most accurate radio
and optical reference frames that will become possible with the next-generation
space astrometry missions in about a decade. The positions of more than 500
active galactic nuclei that are common in the precise Very Long Baseline
Interferometry (VLBI) catalogues and the Sloan Digital Sky Survey (SDSS) Data
Release 4 (DR4) are compared. While obtaining an ``independent'' estimate for
the SDSS coordinate accuracies, we find indications that the assumption of
spatially coincident brightness peaks for the same objects in radio and optical
does not hold for each object.


title: X-ray reflection in the nearby Seyfert 2 galaxy NGC 1068

abstract:
  We use the full broad-band XMM-Newton EPIC data to examine the X-ray spectrum
of the nearby Seyfert 2 galaxy NGC 1068, previously shown to be complex with
the X-ray continuum being a sum of components reflected/scattered from cold
(neutral) and warm (ionised) matter, together with associated emission line
spectra. We quantify the neutral and ionised reflectors in terms of the
luminosity of the hidden nucleus. Both are relatively weak, a result we
interpret on the Unified Seyfert Model by a near side-on view to the putative
torus, reducing the visibility of the illuminated inner surface of the torus
(the cold reflector), and part of the ionised outflow. A high inclination in
NGC 1068 also provides a natural explanation for the large (Compton-thick)
absorbing column in the line-of-sight to the nucleus. The emission line fluxes
are consistent with the strength of the neutral and ionised continuum
components, supporting the robustness of the spectral model.


title: The internal kinematics of dwarf spheroidal galaxies

abstract:
  The status of kinematic observations in Local Group dwarf spheroidal galaxies
(dSphs) is reviewed. Various approaches to the dynamical modelling of these
data are discussed and some general features of dSph dark matter haloes based
on simple mass models are presented.


title:
Axisymmetric simulations of magnetorotational core collapse: Approximate
  inclusion of general relativistic effects

abstract:
  We continue our investigations of the magnetorotational collapse of stellar
cores discussing simulations performed with a modified Newtonian gravitational
potential that mimics general relativistic effects. The approximate TOV
potential used in our simulations catches several features of fully
relativistic simulations quite well. It is able to correctly reproduce the
behavior of models which show a qualitative change both of the dynamics and the
gravitational wave signal when switching from Newtonian to fully relativistic
simulations. If this is not the case, the Newtonian and the approximate TOV
models differ quantitatively. The collapse proceeds to higher densities with
the approximate TOV potential allowing for a more efficient amplification of
the magnetic field by differential rotation. Sufficiently strong magnetic
fields brake down the core's rotation and trigger a contraction phase to higher
densities. Several models exhibit two different kinds of shock generation. Due
to magnetic braking, a first shock wave created during the initial centrifugal
bounce does not suffice to eject any mass, and the core continues to collapse
to supranuclear densities. Another stronger shock wave is generated during the
second bounce as the core exceeds nuclear matter density. The gravitational
wave signal of these models does not fit into the standard classification.
Instead it belongs to the signal type IV introduced by us in the first paper of
this series. This signal type is more frequent for the approximate relativistic
potential than for the Newtonian one. Strongly magnetized models emit a
substantial fraction of their GW power at very low frequencies. A flat spectrum
between 10 Hz and > 100 kHz denotes the generation of a jet-like outflow.
[Abstract abbreviated]


title:
On the reliability of CIV 1549 as an abundance indicator for high
  redshift star-forming galaxies

abstract:
  We reconsider the use of the equivalent width of CIV 1549, EW(CIV), as an
indicator of the oxygen abundance in star-forming galaxies, as proposed by
Heckman et al. for nearby starbursts. We refine the local calibration of
EW(CIV) vs. log (O/H) by using a restricted wavelength window which minimises
blending with interstellar absorption lines. When applied to the stellar
component only of the complex CIV 1549 features in two high redshift galaxies
with good quality spectra, MS1512-cB58 (z = 2.7268) and Q1307-BM1163 (z =
1.4105), the local calibration gives values of the oxygen abundance which are
in good agreement with other metallicity determinations based on nebular
emission and interstellar absorption lines. Our main conclusion is that for
this method to give reliable results at high redshifts, it should only be used
on data of sufficiently high spectral resolution (R > 1000) for stellar and
interstellar CIV components to be clearly separated. Oxygen abundances will be
systematically overestimated if the local calibration is applied to spectra of
high-z galaxies obtained with the low resolving powers (R ~ 200-300) of many
current wide field surveys. It will also be necessary to understand better the
causes of the scatter in the local relation, before we can be confident of
inferences from it at high z.


title:
Various Modes of Helium Mixing in Globular Cluster Giants and Their
  Possible Effects on the Horizontal Branch Morphology

abstract:
  It has been known for a long time that some red giants in globular clusters
exhibit large star-to-star variations in the abundances of light elements that
are not exhibited by field giants. This fact can be taken as evidence that the
extra mixing mechanism(s) that operate in globular cluster giants may be
consequences of star-star interactions in the dense stellar environment. In
order to constrain the extra mixing mechanism(s), we study the influence of
helium enrichment along the red giant branch (RGB) on the evolution of stars
through the horizontal branch. Three possible modes of helium enrichment are
considered, associated with close encounters of stars in the globular clusters.
We show that as a consequence of the variations in the core mass as well as in
the total mass due to mass loss, the color of horizontal branch models are
distributed over almost all range of horizontal branch. The results are
discussed in relation to the scenario for the origin of the abundance anomalies
and for the effects on the morphology of horizontal branch. We argue that the
star-star interactions can explain not only the source of angular momentum of
rapid rotation but also provide a mechanism for the bimodal distribution of
rotation rates in some globular clusters. We also propose the time elapsed from
the latest core collapse phase during the gravo-thermal oscillations as the
second parameter to explain the variations in HB morphology among the globular
clusters.


title: Impact of Uncertainties in Hadron Production on Air-Shower Predictions

abstract:
  At high energy, cosmic rays can only be studied by measuring the extensive
air showers they produce in the atmosphere of the Earth. Although the main
features of air showers can be understood within a simple model of successive
interactions, detailed simulations and a realistic description of particle
production are needed to calculate observables relevant to air shower
experiments. Currently hadronic interaction models are the main source of
uncertainty of such simulations. We will study the effect of using different
hadronic models available in CORSIKA and CONEX on extensive air shower
predictions.


title: XMM-Newton study of the complex and variable spectrum of NGC 4051

abstract:
  We study the X-ray spectral variability of the Narrow Line Seyfert 1 galaxy
NGC 4051 as observed during two XMM-Newton observations. The data show evidence
for a neutral and constant reflection component and for constant emission from
photoionized gas, which are included in all spectral models. The nuclear
emission can be modelled both in terms of a ``standard model'' (pivoting power
law plus a black body component for the soft excess) and of a two--component
one (power law plus ionized reflection from the accretion disc). The standard
model results indicate that the soft excess does not follow the standard black
body law. Moreover, although the spectral slope is correlated with flux, which
is consistent with spectral pivoting, the hardest photon indexes are so flat as
to require rather unusual scenarios. These problems can be solved in terms of
the two-component model in which the soft excess is not thermal, but due to the
ionized reflection component. The variability of the reflection component from
the inner disc closely follows the predictions of the light bending model,
suggesting that most of the primary nuclear emission is produced in the very
innermost regions, only a few gravitational radii from the central black hole.
(abridged)


title:
The SAURON project - VI. Line strength maps of 48 elliptical and
  lenticular galaxies

abstract:
  We present absorption line strength maps of 48 representative elliptical and
lenticular galaxies obtained as part of the SAURON survey of nearby galaxies.
Using high-quality spectra, spatially binned to a constant signal-to-noise, we
measure four key age, metallicity and abundance ratio sensitive indices from
the Lick/IDS system over a two-dimensional field extending up to approximately
one effective radius. We modify the classical Fe5270 index to define a new
index, Fe5270S, which maximizes the usable spatial coverage of SAURON. Maps of
Hbeta, Fe5015, Mgb and Fe5270S are presented for each galaxy. We use the maps
to compute average line strengths integrated over circular apertures of
one-eighth effective radius, and compare the resulting relations of index
versus velocity dispersion with previous long-slit work. The metal line
strength maps show generally negative gradients with increasing radius roughly
consistent with the morphology of the light profiles. Remarkable deviations
from this general trend exist, particularly the Mgb isoindex contours appear to
be flatter than the isophotes of the surface brightness for about 40% of our
galaxies without significant dust features. Generally these galaxies exhibit
significant rotation. We infer from this that the fast-rotating component
features a higher metallicity and/or an increased Mg/Fe ratio as compared to
the galaxy as a whole. The Hbeta maps are typically flat or show a mild
positive outwards radial gradient, while a few galaxies show strong central
peaks and/or elevated overall Hbeta-strength likely connected to recent
star-formation activity. For the most prominent post-starburst galaxies even
the metal line strength maps show a reversed gradient. (abridged)


title:
Obtaining cosmic ray propagation parameters from diffuse VHE gamma ray
  emission from the Galactic center ridge

abstract:
  The recent discovery of diffuse, VHE gamma radiation from the Galactic center
ridge by the H.E.S.S. telescope allow for the first time the direct
determination of parameters of galactic cosmic ray propagation models. In this
paper we show that the diffuse gamma radiation near the Galactic center may be
explained by the interaction of VHE cosmic ray (CR) protons with the
interstellar gas located in several giant molecular clouds leading to a
measurement of the cosmic ray diffusion coefficient for the galactic center
region of k = 1.3 kpc^2 Myr^-1 for a mean proton energy of about 3 TeV, if we
assume that the CR protons originated from a supernova event (Sgr A East),
which took off about 10 kyr ago. This value of k is about 5 to 10 times smaller
than the locally measured value.


title:
Milagro Search for Very High Energy Emission from Gamma-Ray Bursts in
  the Swift Era

abstract:
  The recently launched Swift satellite is providing an unprecedented number of
rapid and accurate Gamma-Ray Burst (GRB) localizations, facilitating a flurry
of follow-up observations by a large number of telescopes at many different
wavelengths. The Very High Energy (VHE, >100 GeV) regime has so far been
relatively unexplored. Milagro is a wide field of view (2 sr) and high duty
cycle (> 90%) ground-based gamma-ray telescope which employs a water Cherenkov
detector to monitor the northern sky almost continuously in the 100 GeV to 100
TeV energy range. We have searched the Milagro data for emission from the most
recent GRBs identified within our field of view. These include three Swift
bursts which also display late-time X-ray flares. We have searched for emission
coincident with these flares. No significant detection was made. A 99%
confidence upper limit is provided for each of the GRBs, as well as the flares.


title:
Supernova Neutrino Nucleosynthesis of Light Elements with Neutrino
  Oscillations

abstract:
  Light element synthesis in supernovae through neutrino-nucleus interactions,
i.e., the nu-process, is affected by neutrino oscillations in the supernova
environment. There is a resonance of 13-mixing in the O/C layer, which
increases the rates of charged-current nu-process reactions in the outer
He-rich layer. The yields of 7Li and 11B increase by about a factor of 1.9 and
1.3, respectively, for a normal mass hierarchy and an adiabatic 13-mixing
resonance, compared to those without neutrino oscillations. In the case of an
inverted mass hierarchy and a non-adiabatic 13-mixing resonance, the increase
in the 7Li and 11B yields is much smaller. Observations of the 7Li/11B ratio in
stars showing signs of supernova enrichment could thus provide a unique test of
neutrino oscillations and constrain their parameters and the mass hierarchy.


title: DQ white-dwarf stars with low C abundance: Possible progenitors

abstract:
  The present paper focuses on the evolution of hydrogen-deficient white dwarfs
with the aim of exploring the consequences of different initial envelope
structures on the carbon abundances expected in helium-rich,
carbon-contaminated DQ white dwarfs. In particular, the evolutionary link
between the DQs with low detected carbon abundances and the PG1159, extreme
horizontal branch, and helium-rich R Coronae Borealis (RCrB) stars is explored.
We present full evolutionary calculations that take a self-consistent treatment
of element diffusion into account as well as expectations for the outer layer
chemical stratification of progenitor stars upon entering the white dwarf
regime. We find that PG1159 stars cannot be related to any DQ white dwarfs with
low C abundances. Instead, we suggest that the latter could constitute the
progeny of the giant, helium-rich RCrB stars.


title: Velocity distributions in clusters of galaxies

abstract:
  We employ a high-resolution dissipationless N-body simulation of a galaxy
cluster to investigate the impact of subhalo selection on the resulting
velocity distributions. Applying a lower limit on the present bound mass of
subhalos leads to high subhalo velocity dispersions compared to the diffuse
dark matter (positive velocity bias) and to a considerable deviation from a
Gaussian velocity distribution (kurtosis -0.6). However, if subhalos are
required to exceed a minimal mass before accretion onto the host, the velocity
bias becomes negligible and the velocity distribution is close to Gaussian
(kurtosis -0.15). Recently it has been shown that the latter criterion results
in subhalo samples that agree well with the observed number-density profiles of
galaxies in clusters. Therefore we argue that the velocity distributions of
galaxies in clusters are essentially un-biased. The comparison of the galaxy
velocity distribution and the sound speed, derived from scaling relations of
X-ray observations, results in an average Mach number of 1.24. Altogether 65%
of the galaxies move supersonically and 8% have Mach numbers larger than 2 with
respect to the intra cluster gas.


title:
The AGN Contribution to the Mid-IR Emission of Luminous Infrared
  Galaxies

abstract:
  We determine the contribution of AGN to the mid-IR emission of luminous
infrared galaxies (LIRGs) at z>0.6 by measuring the mid-IR dust continuum slope
of 20,039 mid-IR sources. The 24 micron sources are selected from a
Spitzer/MIPS survey of the NOAO Deep Wide-Field Survey Bo\"otes field and have
corresponding 8 micron data from the IRAC Shallow Survey. There is a clear
bimodal distribution in the 24 micron to 8 micron flux ratio. The X-ray
detected sources fall within the peak corresponding to a flat spectrum in
nufnu, implying that it is populated by AGN-dominated LIRGs, whereas the peak
corresponding to a higher 24 micron to 8 micron flux ratio is likely due to
LIRGs whose infrared emission is powered by starbursts. The 24 micron emission
is increasingly dominated by AGN at higher 24 micron flux densities (f_24): the
AGN fraction of the z>0.6 sources increases from ~9% at f_24 ~ 0.35 mJy to
74+/-20% at f_24 ~ 3 mJy in good agreement with model predictions. Deep 24
micron, small area surveys, like GOODS, will be strongly dominated by starburst
galaxies. AGN are responsible for ~ 3-7% of the total 24 micron background.


title: Chandra Observation of Abell 2065: An Unequal Mass Merger?

abstract:
  We present an analysis of a 41 ks Chandra observation of the merging cluster
Abell 2065 with the ACIS-I detector. Previous observations with ROSAT and ASCA
provided evidence for an ongoing merger, but also suggested that there were two
surviving cooling cores, which were associated with the two cD galaxies in the
center of the cluster. The Chandra observation reveals only one X-ray surface
brightness peak, which is associated with the more luminous, southern cD
galaxy. The gas related with that peak is cool and displaced slightly from the
position of the cD. The data suggest that this cool material has formed a cold
front. On the other hand, in the higher spatial resolution Chandra image, the
second feature to the north is not associated with the northern cD; rather, it
appears to be a trail of gas behind the main cD. We argue that only one of the
two cooling cores has survived the merger, although it is possible that the
northern cD may not have possessed a cool core prior to the merger. We use the
cool core survival to constrain the kinematics of the merger and we find an
upper limit of ~< 1900 km/s for the merger relative velocity. A surface
brightness discontinuity is found at ~140 kpc from the southern cD; the Mach
number for this feature is ${\cal M} = 1.66^{+0.24}_{-0.32}$, although its
nature (shock or cold front) is not clear from the data. We argue that Abell
2065 is an example of an unequal mass merger. The more massive southern cluster
has driven a shock into the ICM of the infalling northern cluster, which has
disrupted the cool core of the latter, if one existed originally. We estimate
that core crossing occurred a few hundred Myr ago, probably for the first time.


title: Stochastic modeling of kHz QPO light curves

abstract:
  The Kluzniak & Abramowicz model explains high frequency, double peak, "3:2"
QPOs observed in neutron star and black hole sources in terms of a non-linear
parametric resonance between radial and vertical epicyclic oscillations of an
almost Keplerian accretion disk. The 3:2 ratio of epicyclic frequencies occurs
only in strong gravity. Rebusco (2004) and Horak (2004) studied the model
analytically: they proved that a small forcing may indeed excite the parametric
3:2 resonance, but they have not explained the physical nature of the forcing.
Here we integrate their equations numerically, dropping the ad hoc forcing, and
adding instead a stochastic term to mimic the action of the very complex
processes that occur in disks as, for example,
  MRI turbulence. We demonstrate that the presence of the stochastic term
triggers the resonance in epicyclic oscillations of nearly Keplerian disks, and
influences their pattern.


title: Revised Diagnostic Diagrams for Planetary Nebulae

abstract:
  Diagnostic diagrams of electron density - excitation for a sample of 613
planetary nebulae are presented. The present extensive sample allows the
definition of new statistical limits for the distribution of planetary nebulae
in the log [Ha/[SII]] vs log [Ha/[NII]], log [Ha/[SII]] vs [SII] 6717/6731 and
log [Ha/[NII]] vs [SII] 6717/6731 planes. The diagrams provide a good
representation of the ranges of physical conditions, indicated by these
emission line ratios, present in planetary nebulae during different
evolutionary stages.


title:
Erratum: "Post-T Tauri Stars in the Nearest OB Association" (AJ, 124,
  1670 [2002])

abstract:
  A few typos in Mamajek, Meyer, & Liebert (2002, AJ, 124, 1670) have been
corrected in this erratum (including two stellar misidentifications and an
incorrect power in the units of a slope). The most significant is the
correction of a sign error in the published polynomial conversion between Tycho
and Johnson-Cousins (B-V) colors.


title: Biography of Hans Albrecht Bethe

abstract: A short biography of Hans Bethe.


title:
The Group Evolution Multiwavelength Study (GEMS): the Sample and
  Datasets

abstract:
  Galaxy groups have been under-studied relative to their richer counterparts
-- clusters. The Group Evolution Multiwavelength Study (GEMS) aims to redress
some the balance. Here we describe the GEMS sample selection and resulting
sample of 60 nearby (distance < 130 Mpc) galaxy groups and our multiwavelength
dataset of X-ray, optical and HI imaging. ROSAT X-ray images of each group are
presented. GEMS also utilizes near-infrared imaging from the 2MASS survey and
optical spectra from the 6dFGS. These observational data are complemented by
mock group catalogues generated from the latest LCDM simulations with gas
physics included. Existing GEMS publications are briefly highlighted as are
future publication plans.


title:
Disentangling effective temperatures of individual eclipsing binary
  components by means of color-index constraining

abstract:
  Eclipsing binary stars are gratifying objects because of their unique
geometrical properties upon which all important physical parameters such as
masses, radii, temperatures, luminosities and distance may be obtained in
absolute scale. This poses strict demand on the model to be free of systematic
effects that would influence the results later used for calibrations, catalogs
and evolution theory. We present an objective scheme of obtaining individual
temperatures of both binary system components by means of color-index
constraining, with the only requirement that the observational data-set is
acquired in a standard photometric system. We show that for a modest case of
two similar main-sequence components the erroneous approach of assuming the
temperature of the primary star from the color index yields temperatures which
are systematically wrong by ~100K.


title: An unbiased deep search for small-area molecular structures

abstract:
  Small-area molecular structures (SAMS) resembling those clumpuscules,
proposed by Pfenniger and Combes (1994) as candidate for baryonic dark matter,
have recently been detected (Heithausen 2002, 2004) in an area where the
shielding is too low for them to survive for a long time. To study the
frequency of occurence of such structures I present the results of an unbiased
deep search for molecular clumpuscules. The area surrounding these structures
has been surveyed using the FCRAO 14m telescope in the CO J=1-0 transition. The
field covered is 20' by 20'. The resulting rms of the data is only 0.04K in a
0.127 km/s wide channel. Also, high-angular resolution observations of the 13CO
and C18O (J=1-0) transitions were obtained with the IRAM Plateau-de-Bure
Interferometer. 3 new SAMS have been detected. The structures have very low
intensities which makes it impossible to detect them in large scale CO surveys
conducted to map the molecular gas of the Milky way. They move with a similar
radial velocity as the surrounding HI gas. The clouds follow the same
size-linewidth relation as found for giant molecular clouds or Galactic cirrus
clouds. The observations clearly show that most of the large linewidths
observed at low angular resolution is caused by a large velocity difference
among the clumps seen at highest angular resolution. At an adopted distance of
100pc the structures have masses of only Jupiter mass or below. My observations
show that SAMS might be an abundant phenomenon in the interstellar medium
however not recognized as such due to their small size. If they are made of
ordinary interstellar matter with solar metallicity they likely contribute only
little to the total interstellar mass.


title: Optical Counterparts of Ultra Luminous X-ray Sources

abstract:
  We present optical identification and characterization of counterparts of
four objects previously catalogued as ultra-luminous X-ray sources. The objects
were selected from the Colbert & Ptak (2002) catalogue. The optical
counterparts are identified as point-like objects with magnitudes in the range
\~17-19. The optical spectra of three of the sources (IXO 32, 37 and 40) show
the presence of emission lines typical of quasars. The position of these lines
allows a precise estimation of their redshifts (2.769, 0.567 and 0.789 for IXO
32, 37 and 40 respectively). The fourth X-ray source, IXO35, is associated with
a red object that has a spectrum typical of an M star in our Galaxy. These
identifications are useful for building clean samples of ULX sources, selecting
suitable targets for future observations and performing statistical studies on
the different populations of X-ray sources.


title: The rate and luminosity function of Short GRBs

abstract:
  We compare the luminosity function and rate inferred from the BATSE short
hard bursts (SHBs) peak flux distribution with the redshift and luminosity
distributions of SHBs observed by Swift/HETE II. The Swift/HETE II SHB sample
is incompatible with SHB population that follows the star formation rate.
However, it is compatible with a distribution of delay times after the SFR.
This would be the case if SHBs are associated with binary neutron star mergers.
The implied SHB rates that we find range from \sim 8 to \sim
30h_{70}^3Gpc^{-3}yr^{-1}. This rate is a much higher than what was previously
estimated and, when beaming is taken into account, it is comparable to the rate
of neutron star mergers estimated from statistics of binary pulsars. If GRBs
are produced in mergers the implied rate practically guarantees detection by
LIGO II and possibly even by LIGO I, if we are lucky. Our analysis, which is
based on observed short hard burst is limited to bursts with luminosities above
10^{49}erg/sec. Weaker bursts may exist but if so they are hardly detected by
BATSE or Swift and hence their rate is very weakly constrained by current
observations. Thus the rate of mergers that lead to a detection of a
gravitational radiation signal might be even higher.


title:
Modeling the star formation history in the ring galaxy Arp 10 with the
  help of spectral indices

abstract:
  We use long-slit spectra obtained with the 6-m telescope BTA (Russian Academy
of Sciences) to investigate the history of star formation in the peculiar ring
galaxy Arp 10. The radial distributions of quasi-Lick spectral indices are
calculated from the observed spectra and are compared with the model spectra,
the latter are generated using the Starburst99 population synthesis code. Our
model includes an outward propagating density wave which triggers star
formation in the gas disk, and an old stellar disk. The metallicity of both old
and young stellar populations is a function of radius. We show that a mix of
the young and old populations is required to explain the radial distribution of
the spectral indices. The density wave propagates outward with a moderate speed
(of order 40 km/s), and the metallicities of both young and old populations
decrease with the radius. The model indices corresponding to the alpha-elements
require somewhat higher metallicities as compared to the Fe-peak elements. We
acknowledge partial support from grant RFBR 04-02-16518.


title:
GBT Observations of IC 443: the Nature of OH(1720 MHz) Masers and OH
  Absorption

abstract:
  We present results of spectral line observations of the ground state
transitions of hydroxyl(OH) toward supernova remnant IC 443 carried out with
the Green Bank Telescope. At a spatial resolution of 7.2 arcminutes we detect
weak, extended OH(1720 MHz) maser emission with OH(1667/5,1612 MHz) absorption
along the southern extent of the remnant, where no bright compact maser sources
have been observed previously. These newly detected SNR-type masers are
coincident with known molecular clumps and a ridge of shocked molecular
hydrogen indicative of the SNR shock front interacting with the adjacent
molecular cloud. Simultaneous observation of all four ground-state transitions
of OH permits us to fit physical conditions of the shocked gas at the
interaction site. A simple two-component model for the line profiles yields the
physical parameters for detected regions of maser emission including excitation
temperature, OH column density and filling factor. Observed line profiles
suggest the shock is largely propagating toward the line-of-sight in the region
of these newly identified weak masers. The implications of shock geometry and
physical parameters in producing extended OH maser emission in SNRs are
explored. We also present VLA radio continuum observations at 330 MHz for
comparison with OH line observations of the remnant.


title: Microquasar Jet Irradiation of the Proto-Solar Nebula?

abstract:
  We explore the possibility that a now-extinct microquasar may have irradiated
the proto-solar neighborhood, causing the 'anomalously' high local 11B/10B
isotopic ratio. Given the population and typical lifetimes of radio-emitting
X-ray binaries, we find the probability of such an event having occurred is not
unreasonable. We comment on some tests of the scenario that could be carried
out by observing the elemental abundances in the vicinity of microquasars, in
particular SS433.


title: Molecular Hydrogen in a Damped Lyman-alpha System at z_abs=4.224

abstract:
  We present the direct detection of molecular hydrogen at the highest redshift
known today (z_abs=4.224) in a Damped Lyman-alpha (DLA) system toward the
quasar PSS J1443+2724. This absorber is remarkable for having one of the
highest metallicities amongst DLA systems at z_abs>3, with a measured iron
abundance relative to Solar of -1.12+/-0.10. We provide for the first time in
this system accurate measurements of NI, MgII, SII and ArI column densities.
The sulfur and nitrogen abundances relative to Solar, -0.63+/-0.10 and
-1.38+/-0.10 respectively, correspond exactly to the primary nitrogen
production plateau. H2 absorption lines are detected in four different
rotational levels (J=0, 1, 2 and 3) of the vibrational ground-state in three
velocity components with total column densities of log N(H2)=17.67, 17.97,
17.48 and 17.26 respectively. The J=4 level is tentatively detected in the
strongest component with log N(H2)~14. The mean molecular fraction is log
f=-2.38+/-0.13, with f=2N(H2)/(2N(H2)+N(HI)). We also measure log
N(HD)/N(H2)<-4.2. The excitation temperatures T_{01} for the two main
components of the system are 96 and 136 K respectively. We argue that the
absorbing galaxy, whose star-formation activity must have started at least
2-5x10^8 yrs before z=4.224, is in a quiescent state at the time of
observation. The density of the gas is small, n_H<=50 cm^{-3}, and the
temperature is of the order of T~90-180 K. The high excitation of neutral
carbon in one of the components can be explained if the temperature of the
Cosmic Microwave Background Radiation has the value expected at the absorber
redshift, T=14.2 K.


title: The Redshift Sensitivities of Dark Energy Surveys

abstract:
  Great uncertainty surrounds dark energy, both in terms of its physics, and
the choice of methods by which the problem should be addressed. Here we
quantify the redshift sensitivities offered by different techniques. We focus
on the three methods most adept at constraining w, namely supernovae, cosmic
shear, and baryon oscillations. For each we provide insight into the family of
w(z) models which are permitted for a particular constraint on either w=w0 or
w=w0+wa(1-a). Our results are in the form of "weight functions", which describe
the fitted model parameters as a weighted average over the true functional
form. For example, we find the recent best-fit from the Supernovae Legacy
Survey (w=-1.023) corresponds to the average value of w(z) over the range
0<z<0.4. Whilst there is a strong dependence on the choice of priors, each
cosmological probe displays distinctive characteristics in their redshift
sensitivities. In the case of proposed future surveys, a SNAP-like supernova
survey probes a mean redshift of z ~ 0.3, with baryon oscillations and cosmic
shear at z ~ 0.6. If we consider the evolution of w, sensitivities shift to
slightly higher redshift. Finally, we find that the weight functions may be
expressed as a weighted average of the popular "principal components".


title: Predicting and analyzing topological correlations in the CMB

abstract:
  The Cosmic Microwave Background (CMB) power spectrum derived from the first
year WMAP data demonstrates an intriguing lack of power at large scales that
cannot be accounted for within the framework of the standard cosmological
model. We explore the possibility that this anomaly could be explained by
waiving the implicit assumption of a simply connected topology, rather than
modifying the physics of the standard model. In particular, we assume that the
Universe is slightly closed and its spatial section can be described by one of
the simplest spherical multi-connected manifolds (the quaternionic, the
octahedral, the truncated cube and the Poincare space). We discuss the
implications for the CMB in each case.


title: On a Site of X-ray Emission in AE Aquarii

abstract:
  An analysis of recently reported results of XMM-Newton observations of AE Aqr
within a hypothesis that the detected X-ray source is located inside the Roche
lobe of the white dwarf is presented. I show this hypothesis to be inconsistent
with the currently adopted model of mass-transfer in the system. Possible
solutions of this problem are briefly discussed.


title: Long Gamma-Ray Bursts as standard candles

abstract:
  As soon as it was realized that long GRBs lie at cosmological distances,
attempts have been made to use them as cosmological probes. Besides their use
as lighthouses, a task that presents mainly the technological challenge of a
rapid deep high resolution follow-up, researchers attempted to find the Holy
Grail: a way to create a standard candle from GRB observables. We discuss here
the attempts and the discovery of the Ghirlanda correlation, to date the best
method to standardize the GRB candle. Together with discussing the promises of
this method, we will underline the open issues, the required calibrations and
how to understand them and keep them under control. Even though GRB cosmology
is a field in its infancy, ongoing work and studies will clarify soon if and
how GRBs will be able to keep up to the promises.


title: On the Location of the Snow Line in a Protoplanetary Disk

abstract:
  In a protoplanetary disk, the inner edge of the region where the temperature
falls below the condensation temperature of water is referred to as the 'snow
line'. Outside the snow line, water ice increases the surface density of solids
by a factor of 4. The mass of the fastest growing planetesimal (the 'isolation
mass') scales as the surface density to the 3/2 power. It is thought that
ice-enhanced surface densities are required to make the cores of the gas giants
(Jupiter and Saturn) before the disk gas dissipates. Observations of the Solar
System's asteroid belt suggest that the snow line occurred near 2.7 AU. In this
paper we revisit the theoretical determination of the snow line. In a
minimum-mass disk characterized by conventional opacities and a mass accretion
rate of 10^-8 solar masses per year, the snow line lies at 1.6-1.8 AU, just
past the orbit of Mars. The minimum-mass disk, with a mass of 0.02 solar, has a
life time of 2 million years with the assumed accretion rate. Moving the snow
line past 2.7 AU requires that we increase the disk opacity, accretion rate,
and/or disk mass by factors ranging up to an order of magnitude above our
assumed baseline values.


title:
The Discovery of a Population of Pre-Main Sequence Stars in N66/NGC346
  from Deep HST/ACS Image

abstract:
  We report the discovery of a rich population of low mass stars in the young,
massive star forming region N66/NGC346 in the Small Magellanic Cloud, from deep
V, I and H alpha images taken with the HST/ACS. These stars have likely formed
together with the NGC346 cluster, ~3-5 Myr ago. Their magnitude and colors are
those of pre-main sequence stars in the mass range 0.6-3 Mo, mostly
concentrated in the main cluster, but with secondary subclusters spread over a
region across ~45 pc. These subclusters appear to be spatially coincident with
previously known knots of molecular gas identified in ground based and ISO
observations. We show that N66/NGC346 is a complex region, being shaped by its
massive stars, and the observations presented here represent a key step towards
the understanding of how star formation occurred and has progressed in this low
metallicity environment.


title: Afterglow Light Curves and Broken Power Laws: A Statistical Study

abstract:
  In gamma-ray burst research it is quite common to fit the afterglow light
curves with a broken power law to interpret the data. We apply this method to a
computer simulated population of afterglows and find systematic differences
between the known model parameters of the population and the ones derived from
the power law fits. In general, the slope of the electron energy distribution
is overestimated from the pre-break light curve slope while being
underestimated from the post-break slope. We also find that the jet opening
angle derived from the fits is overestimated in narrow jets and underestimated
in wider ones. Results from fitting afterglow light curves with broken power
laws must therefore be interpreted with caution since the uncertainties in the
derived parameters might be larger than estimated from the fit. This may have
implications for Hubble diagrams constructed using gamma-ray burst data.


title:
Dynamics and High Energy Emission of the Flaring HST-1 Knot in the M 87
  Jet

abstract:
  Stimulated by recent observations of a radio-to-X-ray synchrotron flare from
HST-1, the innermost knot of the M 87 jet, as well as by a detection of a very
high energy gamma-ray emission from M 87, we investigated the dynamics and
multiwavelength emission of the HST-1 region. We study thermal pressure of the
hot interstellar medium in M 87 and argue for a presence of a gaseous
condensation in its central parts. Interaction of the jet with such a feature
is likely to result in formation of a converging reconfinement shock in the
innermost parts of the M 87 jet. We show that for a realistic set of the
outflow parameters, a stationary and a flaring part of the HST-1 knot located
\~100 pc away from the active center can be associated with the decelerated
portion of the jet matter placed immediately downstream of the point where the
reconfinement shock reaches the jet axis. We discuss a possible scenario
explaining a broad-band brightening of the HST-1 region related to the variable
activity of the central core. We show that assuming a previous epoch of the
high central black hole activity resulting in ejection of excess particles and
photons down along the jet, one may first expect a high-energy flare of HST-1
due to inverse-Comptonisation of the nuclear radiation, followed after a few
years by an increase in the synchrotron continuum of this region. If this is
the case, then the recently observed increase in the knot luminosity in all
spectral bands could be regarded as an unusual echo of the outburst that had
happened previously in the active core of the M 87 radio galaxy.


title: Measuring Magnetic Fields in Ultracool Stars and Brown Dwarfs

abstract:
  We present a new method for direct measurement of magnetic fields on
ultracool stars and brown dwarfs. It takes advantage of the Wing-Ford band of
FeH, which are seen throughout the M and L spectral types. These molecular
features are not as blended as other optical molecular bands, are reasonably
strong through most of the spectral range, and exhibit a response to magnetic
fields which is easier to detect than other magnetic diagnostics, including the
usual optical and near-infrared atomic spectral lines that have heretofore been
employed. The FeH bands show a systematic growth as the star gets cooler. We do
not find any contamination by CrH in the relevant spectral region. We are able
to model cool and rapidly-rotating spectra from warmer, slowly-rotating spectra
utilizing an interpolation scheme based on optical depth scaling. We show that
the FeH features can distinguish between negligible, moderate, and high
magnetic fluxes on low-mass dwarfs, with a current accuracy of about one
kilogauss. Two different approaches to extracting the information from the
spectra are developed and compared. Which one is superior depends on a number
of factors. We demostrate the validity of our new procedures by comparing the
spectra of three M stars whose magnetic fluxes are already known from atomic
line analysis. The low and high field stars are used to produce interpolated
moderate-strength spectra which closely resemble the moderate-field star. The
assumption of linear behavior for the magnetic effects appears to be
reasonable, but until the molecular constants are better understood the method
is subject to that assumption, and rather approximate. Nonetheless, it opens a
new regime of very low-mass objects to direct confirmation and testing of their
magnetic dynamos.


title: The 2005 outburst of the halo black hole X-ray transient XTE J1118+480

abstract:
  We present optical and infrared monitoring of the 2005 outburst of the halo
black hole X-ray transient XTE J1118+480. We measured a total outburst
amplitude of ~5.7+-0.1 mag in the R band and ~5 mag in the infrared J, H and
K_s bands. The hardness ratio HR2 (5-12 keV/3-5 keV) from the RXTE/ASM data is
1.53+-0.02 at the peak of the outburst indicating a hard spectrum. Both the
shape of the light curve and the ratio L_X (1-10 keV)/L_opt resemble the
mini-outbursts observed in GRO J0422+32 and XTE J1859+226. During early
decline, we find a 0.02-mag amplitude variation consistent with a superhump
modulation, like the one observed during the 2000 outburst. Similarly, XTE
J1118+480 displayed a double-humped ellipsoidal modulation distorted by a
superhump wave when settled into a near-quiescence level, suggesting that the
disk expanded to the 3:1 resonance radius after outburst where it remained
until early quiescence. The system reached quiescence at R=19.02+-0.03 about
three months after the onset of the outburst. The optical rise preceded the
X-ray rise by at most 4 days. The spectral energy distributions (SEDs) at the
different epochs during outburst are all quasi-power laws with F_nu
proportional to nu^alpha increasing toward the blue. At the peak of the
outburst we derived alpha=0.49+-0.04 for the optical data alone and
alpha=0.1+-0.1 when fitting solely the infrared. This difference between the
optical and the infrared SEDs suggests that the infrared is dominated by a
different component (a jet?) whereas the optical is presumably showing the disk
evolution.


title:
Structural Parameters of Stellar Disks in Edge-on Galaxies from 2MASS
  Images

abstract:
  We analyze the J, H, and Ks 2MASS images of 140 late-type edge-on galaxies
selected from the RFGC catalog (which contains flat galaxies with
major-to-minor axis ratio a/b > 7). The NIR scalelengths (h) and scaleheights
(z0) of the stellar disks are determined for all selected galaxies. The mean
relative ratios of the scaleheights of their stellar disks are 1.00:0.91:0.86
in J:H:Ks bands, respectively. We infer that the scaleheight determined from
the Ks-band images is, on average, 13% larger than the extinction-free
scaleheight. This difference is much larger if the scaleheights were found from
the optical-band images. The relative thickness (z0/h) of the stellar disks
correlates well with their deprojected central surface brightness obtained from
the 2MASS images. This project was partially supported by grant RFBR
04-02-16518.


title:
Constraints on the Evolution of the Primordial Magnetic Field from the
  Small-Scale Cosmic Microwave Background Angular Anisotropy

abstract:
  Recent observations of the cosmic microwave background (CMB) have extended
the measured power spectrum to higher multipoles $l\gtrsim$1000, and there
appears to be possible evidence for excess power on small angular scales. The
primordial magnetic field (PMF) can strongly affect the CMB power spectrum and
the formation of large scale structure. In this paper, we calculate the CMB
temperature anisotropies generated by including a power-law magnetic field at
the photon last-scattering surface (PLSS). We then deduce an upper limit on the
PMF based on our theoretical analysis of the power excess on small angular
scales. We have taken into account several important effects such as the
modified matter sound speed in the presence of a magnetic field. An upper limit
to the field strength of $|B_\lambda|\lesssim$ 4.7 nG at the present scale of 1
Mpc is deduced. This is obtained by comparing the calculated theoretical result
including the Sunyaev-Zeldovich (SZ) effect with recent observed data on the
small-scale CMB anisotropies from the $Wilkinson Microwave Anisotropy Probe$
(WMAP), the Cosmic Background Imager (CBI), and the Arcminute Cosmology
Bolometer Array Receiver (ACBAR). We discuss several possible mechanisms for
the generation and evolution of the PMF.


title:
A Dimensional Study of Disk Galaxies (An excuse to Talk about the Hubble
  Sequence)

abstract:
  We present a highly simplified model of the dynamical structure of a disk
galaxy where only two parmeters fully determine the solution, mass and angular
momentum. We show through simple physical scalings that once the mass has been
fixed, the angular momentum parameter $\lambda$ is expected to regulate such
critical galactic disk properties as colour, thickness of the disk and disk to
bulge ratio. It is hence expected to be the determinant physical ingeredient
resulting in a given Hubble type. A simple analytic estimate of $\lambda$ for
an observed system is provided. An explicit comparison of the distribution of
several galactic parameters against both Hubble type and $\lambda$ is performed
using observed galaxies. Both such distributions exhibit highly similar
characteristics for all galactic properties studied, suggesting $\lambda$ as a
physically motivated classification parameter for disk galaxies.


title:
Interferometric 890 micron Images of High Redshift Submillimeter
  Galaxies

abstract:
  We present high resolution 890 micron images of two 20 mJy submillimeter
galaxies, SMMJ123711+622212 and MIPS~J142824.0+352619, obtained using the
Submillimeter Array (SMA). Using submillimeter interferometric observations
with an angular resolution of 2.5", the coordinates of these high redshift
sources are determined with an accuracy of 0.2". The new SMA data on
SMMJ123711+622212 reveal an unresolved submm source offset to the east by 0.8"
from an optical galaxy found in deep HST images, suggesting either a large
galaxy with a dusty central region, or an interacting galaxy system. The SMA
image of hyper-luminous (LFIR = 3.2 x 10^{13} Lsun) source
MIPS~J142824.0+352619 provides a firm upper limit to the source size of < 1.2.
This constraint provides evidence that the foreground lens is only weakly
affecting the observed high FIR luminosity.


title:
Millimeter Interferometric Investigations of the Energy Sources of Three
  Ultraluminous Infrared Galaxies, UGC 5101, Mrk 273, and IRAS 17208-0014,
  based on HCN to HCO+ Ratios

abstract:
  We present interferometric observations of three ultraluminous infrared
galaxies (ULIRGs; UGC 5101, Mrk 273, and IRAS 17208-0014) in the 3-mm
wavelength range, using the Nobeyama Millimeter Array. Both the HCN (J=1-0) and
HCO+ (J=1-0) molecular lines were observed simultaneously. HCN emission was
clearly detected at the nuclear positions of these ULIRGs, and HCO+ emission
was detected at the nuclear positions of UGC 5101 and IRAS 17208-0014. The HCN
to HCO+ brightness-temperature ratios toward the nuclei of the three ULIRGs
were derived and compared with those of lower luminosity galaxies known to be
dominated by active galactic nuclei (AGNs) or starbursts. In UGC 5101 and Mrk
273, where there is evidence for obscured AGNs from previous observations at
other wavelengths, we found high HCN/HCO+ ratios (>1.8) that are in the range
found for AGN-dominated galaxies. In IRAS 17208-0014, where the presence of a
powerful obscured AGN has been unclear, the ratio (1.7) is in between the
observed values for starburst- and AGN-dominated galaxies. The high HCN/HCO+
brightness-temperature ratios in UGC 5101 and Mrk 273 could be the consequence
of an HCN abundance enhancement, which is expected from chemical effects of the
central X-ray emitting AGN on the surrounding dense molecular gas. Our proposed
millimeter interferometric method based on HCN/HCO+ ratios may be an effective
tool for unveiling elusive buried AGNs at the cores of ULIRGs, especially
because of the negligible dust extinction at these wavelengths.


title:
Chandra and Spitzer unveil heavily obscured quasars in the SWIRE/Chandra
  Survey

abstract:
  Using the large multi-wavelength data set in the chandra/SWIRE Survey (0.6
square degrees in the Lockman Hole), we show evidence for the existence of
highly obscured (Compton-thick) AGN, estimate a lower limit to their surface
density and characterize their multi-wavelength properties. Two independent
selection methods based on the X-ray and infrared spectral properties are
presented. The two selected samples contain 1) 5 X-ray sources with hard X-ray
spectra and column densities > 10^24 cm-2, and 2) 120 infrared sources with red
and AGN-dominated infrared spectral energy distributions (SEDs). We estimate a
surface density of at least 25 Compton-thick AGN per square degree detected in
the infrared in the chandra/SWIRE field of which ~40% show distinct AGN
signatures in their optical/near-infrared SEDs, the remainings being dominated
by the host-galaxy emission. Only ~33% of all Compton-thick AGN are detected in
the X-rays at our depth (F(0.3-8 keV)>10^-15 erg/cm2/s.
  We report the discovery of two sources in our sample of Compton-thick AGN,
SWIRE_J104409.95+585224.8 (z=2.54) and SWIRE_J104406.30+583954.1 (z=2.43),
which are the most luminous Compton-thick AGN at high-z currently known. The
properties of these two sources are discussed in detail with an analysis of
their spectra, SEDs, luminosities and black-hole masses.


title:
A single-degenerate model for the progenitor of the Type Ia supernova
  2002ic

abstract:
  Supernova 2002ic was an atypical Type Ia supernova (SN Ia) with evidence for
substantial amounts of hydrogen associated with the system. Contrary to
previous claims, we show that its unusual properties can be understood within
the framework of one of the most favoured progenitor models, the so-called
supersoft channel. This requires that the donor star was initially relatively
massive ($\sim 3\Ms$) and that the system experienced a delayed dynamical
instability, leading to a large amount of mass loss from the system in the last
few $10^4 $yr before the explosion. This can produce the inferred hydrogen-rich
circumstellar environment, most likely with a disc-like geometry. However, to
apply these models requires a larger accretion efficiency onto the white dwarf
than is assumed in present parameterizations. If this is confirmed, it would
most likely increase estimates for the frequency of the single-degenerate
channel. Based on population synthesis simulations we estimate that not more
than 1 in 100 SNe Ia should belong to this subgroup of SNe Ia.


title:
The ultra-luminous X-ray source in M82: an intermediate mass black hole
  with a giant companion

abstract:
  The starburst galaxy M82 at a distance of 12 million light years, is the host
of an unusually bright $2.4-16\times 10^{40}$ erg/s X-ray point source, which
is best explained by an accreting black hole $10^{2}$ to $10^4$ times more
massive than the Sun. Though the strongest candidate for a so called
intermediate mass black hole, the only support stems from the observed
luminosity and the 0.05-0.1 Hz quasi periodicity in its signal. Interestingly,
the $7-12 $Myr old star cluster MGG-11 which has been associated with the X-ray
source is sufficiently dense that an intermediate mass black hole could have
been produced in the cluster core via collision runaway. The recently
discovered $62.0\pm 2.5$ day periodicity in the X-ray source X-1 further
supports the hypothesis that this source is powered by a black hole several
hundred times more massive than the Sun. We perform detailed binary evolution
simulations with an accreting compact object of $10-5000 \msun $ and find that
the X-ray luminosity, the age of the cluster, the observed quasi periodic
oscillations and the now observed orbital period are explained best by a black
hole of $200-5000 \msun $ that accretes material from a $22-25\msun$ giant
companion in a state of Roche-lobe contact. Interestingly such a companion star
is consistent with the expectation based on the tidal capture in a young and
dense star cluster like MGG-11, making the picture self consistent.


title:
Flux upper limit of gamma-ray emission by GRB050713a from MAGIC
  Telescope observations

abstract:
  The long-duration GRB050713a was observed by the MAGIC Telescope, 40 seconds
after the burst onset, and followed up for 37 minutes, until twilight. The
observation, triggered by a SWIFT alert, covered energies above ~175 GeV. Using
standard MAGIC analysis, no evidence for a gamma signal was found. As the
redshift of the GRB was not measured directly, the flux upper limit, estimated
by MAGIC, is still compatible with the assumption of an unbroken power-law
spectrum extending from a few hundred keV to our energy range.


title:
Solar System Processes Underlying Planetary Formation, Geodynamics, and
  the Georeactor

abstract:
  Only three processes, operant during the formation of the Solar System, are
responsible for the diversity of matter in the Solar System and are directly
responsible for planetary internal-structures, including planetocentric nuclear
fission reactors, and for dynamical processes, including and especially,
geodynamics. These processes are: (i) Low-pressure, low-temperature
condensation from solar matter in the remote reaches of the Solar System or in
the interstellar medium; (ii) High-pressure, high-temperature condensation from
solar matter associated with planetary-formation by raining out from the
interiors of giant-gaseous protoplanets, and; (iii) Stripping of the primordial
volatile components from the inner portion of the Solar System by super-intense
solar wind associated with T-Tauri phase mass-ejections, presumably during the
thermonuclear ignition of the Sun. As described herein, these processes lead
logically, in a causally related manner, to a coherent vision of planetary
formation with profound implications including, but not limited to, (a) Earth
formation as a giant gaseous Jupiter-like planet with vast amounts of stored
energy of protoplanetary compression in its rock-plus-alloy kernel; (b) Removal
of approximately 300 Earth-masses of primordial gases from the Earth, which
began Earth's decompression process, making available the stored energy of
protoplanetary compression for driving geodynamic processes, which I have
described by the new whole-Earth decompression dynamics and which is
responsible for emplacing heat at the mantle-crust-interface at the base of the
crust through the process I have described, called mantle decompression
thermal-tsunami; and, (c)Uranium accumulations at the planetary centers capable
of self-sustained nuclear fission chain reactions.


title: Searching for annihilation radiation from SN 1006 with SPI on INTEGRAL

abstract:
  Historical Type Ia supernovae are a leading candidate for the source of
positrons observed through their diffuse annihilation emission in the Galaxy.
However, search for annihilation emission from individual Type Ia supernovae
has not been possible before the improved sensitivity of \integral. The total
511 keV annihilation flux from individual SNe Ia, as well as their contribution
to the overall diffuse emission, depends critically on the escape fraction of
positrons produced in $^{56}$Co decays. Late optical light curves suggest that
this fraction may be as high as 5%. We searched for positron annihilation
radiation from the historical Type Ia supernova SN 1006 using the SPI
instrument on \integral. We did not detect significant 511 keV line emission,
with a 3$\sigma$ flux upper limit of 0.59 x 10$^{-4}$ ergs cm^-2 s^-1 for \wsim
1 Msec exposure time, assuming a FWHM of 2.5 keV. This upper limit corresponds
to a 7.5% escape fraction, 50% higher than the expected 5% escape scenario, and
rules out the possibility that Type Ia supernovae produce all of the positrons
in the Galaxy (~ 12% escape fraction), if the mean positron lifetime is less
than 10$^{5}$ years. Future observations with \integral will provide stronger
limits on the escape fraction of positrons, the mean positron lifetime, and the
contribution of Type Ia supernovae to the overall positron content of the
Galaxy.


title: Instabilities of rotating compact stars: a brief overview

abstract:
  Direct observations of gravitational waves will open in the near future new
windows on the Universe. Among the expected sources, instabilities of rotating
compact astrophysical objects are waited to be detected with some impatience as
this will sign the birth of ``gravitational waves asteroseismology'', a crucial
way to improve our knowledge of matter equation of state in conditions that
cannot be reproduced in a lab. However, the theoretical work needed to really
get informations from to-be-detected signals is still quite large, numerical
simulations having become a necessary key ingredient. This article tries to
provide a short overview of the main physical topics involved in this field
(general relativity, gravitational waves, instabilities of rotating fluids,
{\it etc.}), concluding with a brief description of the work that was done in
Paris-Meudon Observatory by Silvano Bonazzola and collaborators.


title:
The faint 2005 hard state outburst of Aquila X-1 seen by INTEGRAL and
  RXTE

abstract:
  We report on the spectral analysis of RXTE and INTEGRAL data of the 2005
April outburst of the transient Atoll source Aql X-1. Although this outburst is
one of the faintest ever detected for this source in the soft X-rays
(RXTE/ASM), one of our INTEGRAL observations, taken close to the soft X-ray
peak, shows that the source flux was quite high, with a 20-200 keV flux of 2.05
x 10^-9 erg cm^-2 s^-1. On this occasion we detect the source up to 150 keV for
the first time. We compare and discuss the similarity of the source behavior
with that of black hole transients especially XTE J1550-564.