title:
Evidence for an intermediate mass black hole and a multi-zone warm
  absorber in NGC 4395

abstract:
  We report on the results of an analysis in the X-ray band of a recent long
ASCA observation of NGC 4395, the most variable low-luminosity AGN known. A
relativistically-broadened iron line at ~6.4 keV is clearly resolved in the
time-averaged spectrum, with an equivalent width of 310^{+70}_{-90} eV.
Time-resolved spectral analysis of the heavily absorbed soft X-ray band
confirms the existence of a variable, multi-zone warm absorber in this source,
as proposed in a previous analysis of a shorter ASCA observation. The light
curve of the source is wildly variable on timescales of hours or less, and a
factor of nearly 10 change in count-rate was recorded in a period of less than
2000 s. The long observation and variability of the source allowed the power
density spectrum (PDS) to be constructed to an unprecedented level of detail.
There is evidence for a break in the PDS from a slope of \alpha~1 to \alpha~1.8
at a frequency of around 3 \times 10^{-4} Hz. The central black hole mass of
NGC 4395 is estimated to be approximately 10^4-10^5 solar masses using the
break in the PDS, a result consistent with previous analyses using optical and
kinematical techniques.


title: Disk-Driven Outflows in AGNs

abstract:
  Analysis of spectral absorption features has led to the identification of
several distinct outflow components in AGNs. The outflowing gas is evidently
photoionized by the nuclear continuum source and originates in the accretion
flow toward the central black hole. The most likely driving mechanisms are
continuum and line radiation pressure and magnetic stresses. The theoretical
modeling of these outflows involves such issues as: (1) Which of the above
mechanisms actually contributes in each case? (2) How is the gas uplifted from
the underlying accretion disk? (3) How can the intense central continuum
radiation be shielded to allow efficient radiative driving? (4) Is the outflow
continuous or clumpy, and, if clumpy, what is the nature and dynamical state of
the ``clouds''? This review summarizes recent theoretical and observational
results that bear on these questions and outlines prospects for further
progress.


title: The Supranova Model and Its Implications

abstract:
  The supranova model for gamma-ray bursts, originally proposed by Vietri &
Stella (1998), has several unique features that make it attractive for the
interpretation of GRBs and their afterglows, and it has emerged as a promising
candidate for modeling the evolution and environment of at least some GRB
sources. This review summarizes the model and its key observational
implications, assesses its strengths and potential weaknesses, and outlines
paths for future observational and theoretical work.


title:
Parent Stars of Extrasolar Planets VII: New Abundance Analyses of 30
  Systems

abstract:
  The results of new spectroscopic analyses of 30 stars with giant planet
and/or brown dwarf companions are presented. Values for Teff and [Fe/H] are
used in conjunction with Hipparcos data and Padova isochrones to derive masses,
ages, and theoretical surface gravities. These new data are combined with
spectroscopic and photometric metallicity estimates of other stars harboring
planets and published samples of F, G, and K dwarfs to compare several subsets
of planet bearing stars with similarly well-constrained control groups. The
distribution of [Fe/H] values continues the trend uncovered in previous studies
in that stars hosting planetary companions have a higher mean value than
otherwise similar nearby stars. We also investigate the relationship between
stellar mass and the presence of giant planets and find statistically marginal
but suggestive evidence of a decrease in the incidence of radial velocity
companions orbiting relatively less massive stars. If confirmed with larger
samples, this would represent a critical constraint to both planetary formation
models as well as to estimates of the distribution of planetary systems in our
galaxy.


title:
Precision Cosmology from the Lyman-alpha Forest: Power Spectrum and
  Bispectrum

abstract:
  We investigate the promise of the Ly-alpha forest for high precision
cosmology in the era of the Sloan Digital Sky Survey using low order N-point
statistics. We show that with the existing data one can determine the
amplitude, slope and curvature of the slope of the matter power spectrum with a
few percent precision. Higher order statistics such as the bispectrum provide
independent information that can confirm and improve upon the statistical
precision from the power spectrum alone. The achievable precision is comparable
to that from the cosmic microwave background with upcoming satellites, and
complements it by measuring the power spectrum amplitude and shape at smaller
scales. Since the data cover the redshift range 2<z<4, one can also extract the
evolution of the growth factor and Hubble parameter over this range, and
provide useful constraints on the presence of dark energy at z>2.


title:
Constraints to the evolution of Ly-Alpha bright galaxies between z=3 and
  z=6

abstract:
  Galaxies at high redshift with a strong Ly-Alpha emission line trace massive
star formation in the absence of dust, and can therefore be regarded as a prime
signature of the first major starburst in galaxies. We report results of the
Ly-Alpha search within the Calar Alto Deep Imaging Survey (CADIS). With imaging
Fabry-Perot interferometer CADIS can detect emission lines in three waveband
windows free of night-sky emission lines at 700nm, 820nm, and 920nm. The
typical flux detection limit for Ly-Alpha emission redshifted into these
windows, Flim > 3X10^(-20) Wm^(-2), corresponds to (unobscured) star formation
rates of >10Msun/yr at z=6. Candidate Ly-Alpha-emitting galaxies are selected
from the total emission line sample, which contains more than 97% of objects at
z<1.2, by the absence of flux below the Lyman limit (B-band "dropouts"), and
the non-detection of secondary emission lines in narrow band filters. We have
detected 5 bright Ly-Alpha-emitting galaxy candidates at z ~ 4.8, and 11
candidates at z ~ 5.7. For two of four observed Ly-Alpha candidates, one
candidate at z ~ 4.8, and the other at z ~ 5.7, the emission line detected with
the Fabry-Perot has been verified spectroscopically at the VLT. When compared
to Ly-Alpha surveys at z<3.5 even the upper limits set by our list of
candidates show that bright Ly-Alpha galaxies are significantly rarer at z>5
than the assumption of a non-evolving population would predict. Therefore we
conclude that the Ly-Alpha bright phase of primeval star formation episodes
reached its peak at redshifts between 3 and 6.


title: The Multiplicity Function of Galaxies

abstract:
  The multiplicity function (MF) of groups and clusters of galaxies is
determined using galaxy catalogues extracted from a set of Digitized Palomar
Sky Survey (DPOSS) plates. The two different types of structures (of low and
high richness) were identified using two different algorithms: a modified
version of the van Albada method for groups, and a peak finding algorithm for
larger structures. In a 300 sq. deg. area up to z<0.2, we find 2944 groups and
179 clusters. Our MF covers a wide range of richnesses, from 2 to 200, and the
two MF's derived by the two algorithms match smoothly without the need for
additional conditions or normalisations. The resulting multiplicity function,
of slope alpha= -2.08 +- 0.07, strongly resembles a power law.


title:
Roche tomography of cataclysmic variables -- II. Images of the secondary
  stars in AM Her, QQ Vul, IP Peg and HU Aqr

abstract:
  We present a set of Roche tomography reconstructions of the secondary stars
in the cataclysmic variables AM Her, QQ Vul, IP Peg and HU Aqr. The image
reconstructions show distinct asymmetries in the irradiation pattern for all
four systems which can be attributed to shielding of the secondary star by the
accretion stream/column in AM Her, QQ Vul and HU Aqr, and increased irradiation
by the bright spot in IP Peg. We use the entropy landscape technique to derive
accurate system parameters (M1, M2, i and gamma) for the four binaries. In
principle, this technique should provide the most reliable mass determinations
available, since the intensity distribution across the secondary star is known.
We also find that the intensity distribution can systematically affect the
value of gamma derived from circular orbit fits to radial velocity variations.


title:
Star forming rates between z=0.25 and z=1.2 from the CADIS emission line
  survey

abstract:
  The emission line survey within the Calar Alto Deep Imaging Survey (CADIS)
detects emission line galaxies by a scan with an imaging Fabry-Perot
interferometer. It covers 5 fields of > 100 square arcmin each in three
wavelengths windows centered on lambda ~ 700, 820, and 920nm, and reaches to a
typical limiting line flux of 3 x 10^(-20) W m^(-2). This is the deepest
emission line survey covering a field of several 100 square arcmin. Galaxies
between z = 0.25 and z = 1.4 are detected by prominent emission lines (from
Halpha to [OII]372.7) falling into the FP scans. Additional observations with a
dozen medium band filters allow to establish the line identification and thus
the redshift of the galaxies to better than sigma(z) =0.001. On the basis of a
total of more than 400 emission line galaxies detected in Halpha (92 galaxies),
[OIII]500.7 (124 galaxies), or [OII]372.7 (222 galaxies) we measure the
instantaneous star formation rate (SFR) in the range 0.24 < z < 1.21. With this
purely emission line selected sample we are able to reach much fainter emission
line galaxies than previous, continuum-selected samples. Thus completeness
corrections are much less important. Our results substantiates the indications
from previous studies (based on small galaxy samples) that the SFR decreases by
a factor of ~20 between z = 1.2 and today. In fact, for a Omega(m) = 0.3,
Omega(Lambda) = 0.7 cosmology, we find an exponential decline rho(SFR)
proportional to exp(-lookback_time) / 2.6Gyr). The inferred SF density is in
perfect agreement with that deduced from the FIR emission of optically selected
galaxies which is explained by a large overlap between both populations. We
show that self-consistent extinction corrections of both our emission lines and
the UV continua lead to consistent results for the SF density.


title:
The history of the iron K-alpha line profile in the Piccinotti AGN
  ESO198-G24

abstract:
  This paper presents ASCA (July 1997), XMM-Newton (December 2000) and BeppoSAX
(January 2001) observations of the Piccinotti Seyfert 1 galaxy ESO198-G24. The
BeppoSAX 0.1-200 keV spectrum exhibits reprocessing features, probably produced
by an X-ray illuminated, relativistic accretion disk subtending a solid angle
\~2 pi. During the XMM-Newton observation the fluorescent iron K-alpha line
profile (centroid energy E~6.4 keV) was broad and twice as bright as in the
BeppoSAX observation. An additional emission feature (E~5.7 keV), detected at
the 96.3% confidence level, may be part of a relativistic, double-peaked
profile. By contrast, in the earlier ASCA observation the line profile is
dominated by a remarkably narrow "core" (intrinsic width <50 eV). If this
component is produced by reflection off the inner surface of a molecular torus,
its large Equivalent Width (~300 eV) most likely represents the "echo" of a
previously brighter flux state, in agreement with the dynamical range covered
by the historical X-ray light curve in ESO198-G24.


title:
The High-Energy Polarization-Limiting Radius of Neutron Star
  Magnetospheres I -- Slowly Rotating Neutron Stars

abstract:
  In the presence of strong magnetic fields, the vacuum becomes a birefringent
medium. We show that this QED effect decouples the polarization modes of
photons leaving the NS surface. Both the total intensity and the intensity in
each of the two modes is preserved along a ray's path through the neutron-star
magnetosphere. We analyze the consequences that this effect has on aligning the
observed polarization vectors across the image of the stellar surface to
generate large net polarizations. Counter to previous predictions, we show that
the thermal radiation of NSs should be highly polarized even in the optical.
When detected, this polarization will be the first demonstration of vacuum
birefringence. It could be used as a tool to prove the high magnetic field
nature of AXPs and it could also be used to constrain physical NS parameters,
such as $R/M$, to which the net polarization is sensitive.


title: White Dwarf Sequences in Dense Star Clusters

abstract:
  We use the results of realistic N-body simulations to investigate the
appearance of the white dwarf population in dense star clusters. We show that
the presence of a substantial binary population in a star cluster, and the
interaction of this population with the cluster environment, has serious
consequences for the morphology of the observed white dwarf sequence and the
derived white dwarf cooling age of the cluster. We find that over time the
dynamical evolution of the cluster -- mass-segregation, stellar interactions
and tidal stripping -- hampers the use of white dwarfs as tracers of the
initial mass function, and also leads to a significant enhancement of the white
dwarf mass fraction. Future observations of star clusters should be conducted
slightly interior to the half-mass radius of the cluster in order to best
obtain information about the cluster age and initial mass function from the
white dwarf luminosity function. The evolution of binary stars and the cluster
environment must necessarily be accounted for when studying the white dwarf
populations of dynamically evolved star clusters.


title: Supernova Reverse Shocks and SiC Growth

abstract:
  We present new mechanisms by which the isotopic compositions of X-type grains
of presolar SiC are altered by reverse shocks in Type II supernovae. We address
three epochs of reverse shocks: pressure wave from the H envelope near t =
10$^6$s; reverse shock from the presupernova wind near 10$^8-10^9$s; reverse
shock from the ISM near 10$^{10}$s. Using 1-D hydrodynamics we show that the
first creates a dense shell of Si and C atoms near 10$^6$s in which the SiC
surely condenses. The second reverse shock causes precondensed grains to move
rapidly forward through decelerated gas of different isotopic composition,
during which implantation, sputtering and further condensation occur
simultaneously. The third reverse shock causes only further ion implantation
and sputtering, which may affect trace element isotopic compositions. Using a
25M$_{\odot}$ supernova model we propose solutions to the following unsolved
questions: where does SiC condense?; why does SiC condense in preference to
graphite?; why is condensed SiC $^{28}$Si-rich?; why is O richness no obstacle
to SiC condensation?; how many atoms of each isotope are impacted by a grain
that condenses at time t$_0$ at radial coordinate r$_0$? These many
considerations are put forward as a road map for interpreting SiC X grains
found in meteorites and their meaning for supernova physics.


title: Signatures of high energy protons in pulsar winds

abstract:
  The resonant cyclotron absorption model is very successful in describing
particle acceleration in plerions. A sensible prediction of this model is the
presence of a substantial amount of relativistic protons in pulsar winds.
Although difficult to detect, these protons may show up through their
interactions either with the photons in the plerion environment or with the
thermal gas in the supernova ejecta. Inelastic proton-proton (p-p) collisions
are expected to be very effective in young objects, resulting in a copious
production of neutral and charged pions. Charged pions produced during the
first few hundred years after the supernova explosion may have time to decay
into muons, whose subsequent decay may provide an additional source of
electrons and positrons in these nebulae, that sums up to the pulsar input.
These secondary leptons evolve just as the pairs in the pulsar wind, and
signatures of their presence could be found, in principle, even in the
synchrotron spectrum of older objects. p-p collisions may remain fairly
efficient even in moderately old objects resulting in the production of TeV
gamma-rays and neutrinos. We apply our calculations to the case of the Crab
Nebula, the best studied plerion insofar, and find that existing data already
allow to infer interesting constraints on the physical properties of the Crab
pulsar wind.


title: Accretion Flow Along a Dipolar Field: Application to Intermediate Polars

abstract:
  A hydrodynamic formulation for accretion flow channeled by a dipolar magnetic
field is constructed using a curvi-linear coordinate system natural to the
field structure. We solve the hydrodynamic equations and determine the
velocity, density and temperature profiles of the post-shock accretion flow.
The results are applied to accretion flows in intermediate polars. We have
found that for systems with massive white dwarfs (~1Msolar) the temperature
profiles in the flow can differ significantly to those obtained from models in
which the accretion column is assumed to be cylindrical.


title:
3D Simulations of Relativistic Precessing Jets Probing the Structure of
  Superluminal Sources

abstract:
  We present the results of a three-dimensional, relativistic, hydrodynamic
simulation of a precessing jet into which a compact blob of matter is injected.
A comparison of synthetic radio maps computed from the hydrodynamic model,
taking into account the appropriate light travel time delays, with those
obtained from observations of actual superluminal sources shows that the
variability of the jet emission is the result of a complex combination of phase
motions, viewing angle selection effects, and non-linear interactions between
perturbations and the underlying jet and/or the external medium. These results
question the hydrodynamic properties inferred from observed apparent motions
and radio structures, and reveal that shock-in-jet models may be overly
simplistic.


title:
Amplitude and frequency variability of the pulsating DB white dwarf
  stars KUV 05134+2605 and PG 1654+160 observed with the Whole Earth Telescope

abstract:
  We have acquired new time series photometry of the two pulsating DB white
dwarf stars KUV 05134+2605 and PG 1654+160 with the Whole Earth Telescope.
Additional single-site photometry is also presented. We use all these data plus
all available archival measurements to study the temporal behaviour of the
pulsational amplitudes and frequencies of these stars for the first time.
  We demonstrate that both KUV 05134+2605 and PG 1654+160 pulsate in many modes
whose amplitudes are variable in time; some frequency variability of PG
1654+160 is also indicated. Beating of multiple pulsation modes cannot explain
our observations; the amplitude variability must therefore be intrinsic. We
cannot find stable modes to be used for determinations of the evolutionary
period changes of the stars. Some of the modes of PG 1654+160 appear at the
same periods whenever detected. The mean spacing of these periods (about 40s)
suggests that they are probably caused by non-radial gravity-mode pulsations of
spherical degree l=1. If so, PG 1654+160 has a mass around 0.6 Msun.
  The time scales of the amplitude variability of both stars (down to two
weeks) are consistent with theoretical predictions of resonant mode coupling, a
conclusion which might however be affected by the temporal distribution of our
data.


title: What can we learn about cosmic structure from gravitational waves?

abstract:
  Observations of low frequency gravitational waves by the space-based LISA
mission will open a new observational window on the early universe and the
emergence of structure. LISA will observe the dynamical coalescence of massive
black hole binaries at high redshifts, giving an unprecedented look at the
merger history of galaxies and the reionization epoch. LISA will also observe
gravitational waves from the collapse of supermassive stars to form black
holes, and will map the spacetime in the central regions of galaxy cusps at
high precision.


title:
The Field Condition: A New Constraint of Spatial Resolution in
  Simulations of the nonlinear Development of Thermal Instability

abstract:
  We present the dynamics of a thermally bistable medium using one-dimensional
numerical calculations, including cooling, heating, thermal conduction, and
physical viscosity.We set up a two-phase medium from a thermally unstable
one-phase medium and follow its long-term evolution. To clarify the role of
thermal conduction, we compare the results of the two models, with and without
thermal conduction. The calculations show that the thermal conduction helps to
generate the kinetic energy of translational motions of the clouds. Next, we
focus on spatial resolution because we have to resolve the Field length
$\lambda_{\rm F}$, which is the characteristic length scale of the thermal
conduction. The results show convergence only when thermal conduction is
included and a large enough cell number is used. We find it necessary to
maintain a cell size of less than $\lambda_{\rm F}/3$ to achieve a converged
motion in the two-phase medium. We refer to the constraint that $\lambda_{\rm
F}/3$ be resolved as the ``Field condition''. The inclusion of thermal
conduction to satisfy the Field condition is crucial to numerical studies of
thermal instability (TI) and may be important for studies of the turbulent
interstellar two-phase medium: the calculations of TI without thermal
conduction may be susceptible to contamination by artificial phenomena that do
not converge with increasing resolutions.


title:
Asteroseismological studies of three Beta Cephei stars: IL Vel, V433 Car
  and KZ Mus

abstract:
  We have acquired between 127 and 150 h of time-resolved multicolour
photometry for each of the three Beta Cephei stars IL Vel, V433 Car and KZ Mus
over a time span of four months from two observatories. All three objects are
multiperiodic with at least three modes of pulsation. Mode identification from
the relative colour amplitudes is performed. We obtain unambiguous results for
the two highest-amplitude modes of IL Vel (both are l=1) and the three
strongest modes of KZ Mus (l=2,0 and 1), but none for V433 Car. Spectroscopy
shows the latter star to be a fast rotator (v sin i = 240 km/s), whereas the
other two have moderate v sin i (65 and 47 km/s, respectively). We performed
model calculations with the Warsaw-New Jersey stellar evolution and pulsation
code. We find that IL Vel is an object of about 12 Msun in the second half of
its main sequence evolutionary track. Its two dipole modes are most likely
rotationally split components of the mode originating as p1 on the ZAMS; one of
these modes is m=0. V433 Car is suggested to be an unevolved 13 Msun star just
entering the Beta Cephei instability strip. KZ Mus seems less massive (about
12.7 Msun) and somewhat more evolved, and its radial mode is probably the
fundamental one. In this case its quadrupole mode would be the one originating
as g1, and its dipole mode would be p1. It is suggested that mode
identification of slowly rotating Beta Cephei stars based on photometric colour
amplitudes is reliable; we estimate that a relative accuracy of 3% in the
amplitudes is sufficient for unambiguous identifications. Due to the good
agreement of our theoretical and observational results we conclude that the
prospects for asteroseismology of multiperiodic slowly rotating Beta Cephei
star are good.


title: A Search for Pulsars in Quiescent Soft X-Ray Transients. I

abstract:
  We have carried out a deep search at 1.4 GHz for radio pulsed emission from
six soft X-ray transient sources observed during their X-ray quiescent phase.
The commonly accepted model for the formation of the millisecond radio pulsars
predicts the presence of a rapidly rotating, weakly magnetized neutron star in
the core of these systems. The sudden drop in accretion rate associated with
the end of an X-ray outburst causes the Alfv\`en surface to move outside the
light cylinder, allowing the pulsar emission process to operate. No pulsed
signal was detected from the sources in our sample. We discuss several
mechanisms that could hamper the detection and suggest that free-free
absorption from material ejected from the system by the pulsar radiation
pressure could explain our null result.


title:
Correlations of Globular Cluster Properties: Their Interpretations and
  Uses

abstract:
  Correlations among the independently measured physical properties of globular
clusters (GCs) can provide powerful tests for theoretical models and new
insights into their dynamics, formation, and evolution. We review briefly some
of the previous work, and present preliminary results from a comparative study
of GC correlations in the Local Group galaxies. The results so far indicate
that these diverse GC systems follow the same fundamental correlations,
suggesting a commonality of formative and evolutionary processes which produce
them.


title:
Search for a Point-Source Counterpart of the Unidentified Gamma-Ray
  Source TeV J2032+4130 in Cygnus

abstract:
  We have made a multiwavelength study of the overlapping error boxes of the
unidentified gamma-ray sources TeV J2032+4130 and 3EG J2033+4118 in the
direction of the Cygnus OB2 association (d = 1.7 kpc) in order to search for a
point-source counterpart of the first unidentified TeV source. Optical
identifications and spectroscopic classifications for the brighter X-ray
sources in ROSAT PSPC and Chandra ACIS images are obtained, without finding a
compelling counterpart. The classified X-ray sources are a mix of early and
late-type stars, with one exception. The brightest source in the Chandra
observation is a new, hard absorbed source that is both transient and rapidly
variable. It lies 7' from the centroid of the TeV emission, which places it
outside of the claimed 2 sigma location (r = 4.8'). A possible eclipse or "dip"
transition is seen in its light curve. With a peak 1-10 keV luminosity of 7 x
10^(32) (d/1.7 kpc})^2 ergs s^(-1), this source could be a quiescent low-mass
X-ray binary that lies beyond the Cyg OB2 association. A coincident, reddened
optical object of R = 20.4, J = 15.4, H = 14.2, and K = 13.4 is observed, but
not yet classified due to the lack of obvious emission or absorption features
in its spectrum. Alternatively, this Chandra} and optical source might be a
considered a candidate for a proton blazar, a long hypothesized type of
radio-weak gamma-ray source. More detailed observations will be needed to
determine the nature of this variable X-ray source, and to assess the
possibility of its connection with TeV J2032+4130.


title: Parallel Universes

abstract:
  I survey physics theories involving parallel universes, which form a natural
four-level hierarchy of multiverses allowing progressively greater diversity.
  Level I: A generic prediction of inflation is an infinite ergodic universe,
which contains Hubble volumes realizing all initial conditions - including an
identical copy of you about 10^{10^29} meters away.
  Level II: In chaotic inflation, other thermalized regions may have different
effective physical constants, dimensionality and particle content.
  Level III: In unitary quantum mechanics, other branches of the wavefunction
add nothing qualitatively new, which is ironic given that this level has
historically been the most controversial.
  Level IV: Other mathematical structures give different fundamental equations
of physics. The key question is not whether parallel universes exist (Level I
is the uncontroversial cosmological concordance model), but how many levels
there are. I discuss how multiverse models can be falsified and argue that
there is a severe "measure problem" that must be solved to make testable
predictions at levels II-IV.


title: Magnetic Protoneutron Star Winds and r-Process Nucleosynthesis

abstract:
  Because of their neutron-richness and association with supernovae,
post-explosion protoneutron star winds are thought to be a likely astrophysical
site for rapid neutron capture nucleosynthesis (the r-process). However, the
most recent models of spherical neutrino-driven protoneutron star winds do not
produce robust r-process nucleosynthesis for `canonical' neutron stars with a
gravitational mass of 1.4M_sun and coordinate radius of 10km. These models fail
variously; either the flow entropy is too low, the electron fraction is too
high, or the dynamical expansion timescale is too long. To date, no models have
included the effects of an ordered dipole magnetic field. We show that a strong
magnetic field can trap the outflow in the neutrino heating region, thus
leading to much higher matter entropy. We estimate both the trapping timescale
and the resulting entropy amplification. For sufficiently large energy
deposition rates, the trapped matter emerges dynamically from the region of
closed magnetic field lines and escapes to infinity. We find that ordered
dipoles with surface fields of greater than 6 times 10^14 Gauss increase the
asymptotic entropy sufficiently for robust r-process nucleosynthesis.


title: Non-Thermal Chemistry in Diffuse Clouds with Low Molecular Abundances

abstract:
  High quality archival spectra of interstellar absorption from C I toward 9
stars, taken with the Goddard High Resolution Spectrograph on the Hubble Space
Telescope, were analyzed. Our sample was supplemented by two sight lines, 23
Ori and B1 Sco, for which the C I measurements of Federman, Welty, & Cardelli
were used. Directions with known CH+ absorption, but only upper limits on
absorption from C2 and CN, were considered for our study. This restriction
allows us to focus on regions where CH+ chemistry dominates the production of
carbon-bearing molecules. Profile synthesis of several multiplets yielded
column densities and Doppler parameters for the C I fine structure levels.
Equilibrium excitation analyses, using the measured column densities as well as
the temperature from H2 excitation, led to values for gas density. These
densities, in conjunction with measurements of CH, CH+, C2, and CN column
densities, provided estimates for the amount of CH associated with CH+
production, which in turn set up constraints on the present theories for CH+
formation in this environment. We found for our sample of interstellar clouds
that on average, 30--40 % of the CH originates from CH+ chemistry, and in some
cases it can be as high as 90 %. A simple chemical model for gas containing
non-equilibrium production of CH+ was developed for the purpose of predicting
column densities for CH, CO, HCO+, CH2+, and CH3+ generated from large
abundances of CH+. Again, our results suggest that non-thermal chemistry is
necessary to account for the observed abundance of CH and probably that of CO
in these clouds.


title:
The Araucaria Project: Dependence of mean K, J, and I absolute
  magnitudes of red clump stars on metallicity and age

abstract:
  (Abridged) We present results of deep near-infrared JK imaging of LMC, SMC,
and the Carina and Fornax dwarf galaxies. A comparison of the
extinction-corrected K-band red clump star magnitudes with the tip of the red
giant branch magnitude, the mean RR Lyrae star V-band magnitude, and the mean
K-band magnitude of Cepheid variables at a period of 10 days (for the LMC and
SMC) strongly suggest that the red clump star absolute K-band magnitude has a
very low (if any) dependence on metallicity over the broad range of
metallicities covered by our target galaxies. This finding is in contrast to
the mean I-band and J-band red clump star magnitudes, which do have a clear
metallicity dependence which we calibrate from our data. Excellent agreement
with the former calibration of the red clump I-band magnitude dependence on
metallicity of Udalski is found from our new data. We use the Galactic cluster
K-band red clump star data of Grocholski and Sarajedini to demonstrate that the
K-band red clump star absolute magnitude also has very little (if any)
dependence on age. The present study therefore provides clear evidence that the
mean K-band magnitude of red clump stars is an excellent distance indicator,
with very small (if any) population corrections to be applied over a large
range in metallicity and age. Comparing derived distances to those coming from
the observed mean I-band magnitudes of the red clump stars, we find evidence
that there is likely to be a problem in the photometric calibration of the
local, solar neighborhood red clump star K-band or I-band magnitudes which
amounts to some 0.2 mag. A re-determination of the absolute photometric
calibration of the Hipparcos-observed nearby red clump stars seems necessary to
resolve this problem.


title:
A generalization of the Lagrangian points: studies of resonance for
  highly eccentric orbits

abstract:
  We develop a framework based on energy kicks for the evolution of
high-eccentricity long-period orbits with Jacobi constant close to 3 in the
restricted circular planar three-body problem where the secondary and primary
masses have mass ratio mu << 1. We use this framework to explore mean-motion
resonances between the test particle and the secondary mass. This approach
leads to (i) a redefinition of resonance orders to reflect the importance of
interactions at periapse; (ii) a pendulum-like equation describing the
librations of resonance orbits; (iii) an analogy between these new fixed points
and the Lagrangian points as well as between librations around the fixed points
and the well known tadpole and horseshoe orbits; (iv) a condition a ~ mu^(-2/5)
for the onset of chaos at large semimajor axis a; (v) the existence of a range
mu < ~5 x 10^(-6) in secondary mass for which a test particle initially close
to the secondary cannot escape from the system, at least in the planar problem;
(vi) a simple explanation for the presence of asymmetric librations in exterior
1:N resonances.


title: The Early Light Curve of the Optical Afterglow of GRB 021211

abstract:
  The Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory observed
GRB 021211 starting 105 s after the burst, among the earliest observations of
an optical afterglow to date. Our well-sampled light curve, consisting of 18
points in the first 10 min and a total of 28 useful observations in the first
2.5 hr after the GRB, directly shows for the first time a break at $t \approx
10$ min. The light curve can be represented as a sum of two components with
power-law decay indices of $-1.82\pm0.02$ and $-0.82\pm0.11$. We hypothesize
that the data before the break were dominated by emission from the reverse
shock, as was previously suggested for GRB 990123. Our data suggest that either
GRB 021211 underwent a dramatic color change at early times, or there are
small-scale variations superimposed on the power-law decay of the reverse-shock
emission. The faintness of GRB 021211, coupled with the fast decline typical of
optical afterglows, suggests that some of the "dark bursts" were not detected
because optical observations commenced too late after the GRB.


title: Imaging Large Scale Structure in the X-ray Sky

abstract:
  We present the first results from a wide solid angle, moderately deep {\it
Chandra} survey of the Lockman Hole North-West region. Our 9 ACIS-I fields
cover an effective solid angle of 0.4 deg$^{2}$ and reach a depth of $3 \times
10^{-16}$ \ergpcmsqps in the 0.4--2 keV band and $3 \times 10^{-15}$
\ergpcmsqps in the 2--8 keV band. The best fit logN-logS for the entire field,
the largest contiguous {\it Chandra} field yet observed, matches well onto that
of the {\it Chandra} Deep Field North. We show that the full range of the
`cosmic variance' previously seen in different {\it Chandra} fields is
reproduced in this small region of the sky. Counts-in-cells analysis shows that
the hard band sources are more strongly correlated than the soft band sources.


title: CMBEASY:: an Object Oriented Code for the Cosmic Microwave Background

abstract:
  We have ported the cmbfast package to the C++ programming language to produce
cmbeasy, an object oriented code for the cosmic microwave background. The code
is available at www.cmbeasy.org. We sketch the design of the new code,
emphasizing the benefits of object orientation in cosmology, which allow for
simple substitution of different cosmological models and gauges. Both gauge
invariant perturbations and quintessence support has been added to the code.
For ease of use, as well as for instruction, a graphical user interface is
available.


title: Gamma-Ray Burst Detection with INTEGRAL/SPI

abstract:
  The spectrometer SPI, one of the two main instruments of the INTEGRAL
spacecraft, has strong capabilities in the Field of Gamma-Ray Burst (GRB)
detections. In its 16 degree Field of view (FoV) SPI is able to trigger and to
localize GRBs. With its large anticoincidence shield (ACS) of 512 kg of BGO
crystals SPI is able to detect GRBs quasi omnidirectionally with a very high
sensitivity. The ACS GRB alerts will provide GRB arrival times with high
accuracy but with no or very rough positional information. The expected GRB
detection rate in SPI's FoV will be one per month and for the ACS around 300
per year. At MPE two SPI software contributions to the real-time INTEGRAL
burst-alert system (IBAS) at the INTEGRAL science data centre ISDC have been
developed. The SPI-ACS branch of IBAS will produce burst alerts and
light-curves with 50 ms resolution. It is planned to use ACS burst alerts in
the 3rd interplanetary network. The SPI-FoV branch of IBAS is currently under
development at MPE. The system is using the energy and timing information of
single and multiple events detected by the Germanium-camera of SPI. Using the
imaging algorithm developed at the University of Birmingham the system is
expected to locate strong bursts with an accuracy of better than 1 degree.


title:
Is evidence for enhanced mass transfer during dwarf-nova outbursts well
  substantiated?

abstract:
  Outburst mechanisms of SU UMa-type dwarf novae are discussed. Two competing
models were proposed; a pure disk instability model called the thermal-tidal
instability model (TTI model) and the enhanced mass transfer model (EMT model).
Observational evidence for enhanced mass transfer from the secondary star
during outbursts is critically examined. It is demonstrated that most evidence
for enhanced mass transfer is not well substantiated. Patterson et al. (2002)
have recently claimed to have found evidence for enhanced mass transfer during
the 2001 outburst of WZ Sge. We show that their evidence is probably due to a
misinterpretation of their observed light curves. Our theoretical analysis also
shows that irradiation during outburst should not affect the mass transfer
rate. A refinement of the TTI model is proposed that can explain why superhumps
appear a few days after the superoutburst maximum in some SU UMa stars. We
present our own interpretation of the overall development of the 2001 outburst
of WZ Sge based on the TTI model that does not require the assumption of an
unproved enhanced mass transfer.


title:
On the structure of the burst and afterglow of Gamma-Ray Bursts I: the
  radial approximation

abstract:
  We have proposed three paradigms for the theoretical interpretation of
gamma-ray bursts (GRBs). (1) The relative space-time transformation (RSTT)
paradigm emphasizes how the knowledge of the entire world-line of the source
from the moment of gravitational collapse is a necessary condition to interpret
GRB data. (2) The interpretation of the burst structure (IBS) paradigm
differentiates in all GRBs between an injector phase and a beam-target phase.
(3) The GRB-supernova time sequence (GSTS) paradigm introduces the concept of
induced supernova explosion in the supernovae-GRB association. These three
paradigms are illustrated using our theory based on the vacuum polarization
process occurring around an electromagnetic black hole (EMBH theory) and using
GRB 991216 as a prototype. We illustrate the five fundamental eras of the EMBH
theory: the self acceleration of the $e^+e^-$ pair-electromagnetic plasma (PEM
pulse), its interaction with the baryonic remnant of the progenitor star (PEMB
pulse). We then study the approach of the PEMB pulse to transparency, the
emission of the proper GRB (P-GRB) and its relation to the ``short GRBs''.
Finally the three different regimes of the afterglow are described within the
fully radiative and radial approximations. The best fit of the theory leads to
an unequivocal identification of the ``long GRBs'' as extended emission
occurring at the afterglow peak (E-APE). The relative intensities, the time
separation and the hardness ratio of the P-GRB and the E-APE are used as
distinctive observational test of the EMBH theory and the excellent agreement
between our theoretical predictions and the observations are documented. The
afterglow power-law indexes in the EMBH theory are compared and contrasted with
the ones in the literature, and no beaming process is found for GRB 991216.


title: Timing, glitches and braking index of PSR B0540-69

abstract:
  We report a pulse-time history of PSR B0540$-$69 based on the analysis of an
extended Data set including ASCA, BeppoSAX and RXTE observations spanning a
time interval of about 8 years. This interval includes also the epoch of the
glitch episode reported by Zhang et al. (2001). Our analysis shows the presence
of a relevant timing noise and does not give a clear evidence of the glitch
occurrence. We performed an accurate evaluation of the main timing parameters,
$\nu$, $\dot{\nu}$ and $\ddot{\nu}$ and derived a mean braking index of
$n=2.125\pm0.001$ quite different from the lower value found by Zhang et al.
(2001), but in rather good agreement with other several values reported in the
literature.


title: Search for relativistic beaming in ultraluminous X-ray sources

abstract:
  The nature of the ultraluminous X-ray sources (ULX) is still to be
understood. Several hypotheses have been suggested to explain the high X-ray
luminosity: stellar mass black holes with emission collimated by relativistic
effects or anisotropies in the accretion disk, intermediate mass black holes,
young supernovae remnants, background active galactic nuclei. To discriminate
among the above hypotheses, the search for relativistic effects can be a
valuable "pathfinder". Here we propose a list of ULX candidates suitable to
show relativistic beaming


title: On the generation of UHECRs in GRBs: a reappraisal

abstract:
  We re-examine critically the arguments raised against the theory that Ultra
High Energy Cosmic Rays observed at Earth are produced in Gamma Ray Bursts.
These include the limitations to the highest energy attainable by protons
around the bursts' shocks, the spectral slope at the highest energies, the
total energy released in non--thermal particles, the occurrence of doublets and
triplets in the data reported by AGASA. We show that, to within the
uncertainties in our current knowledge of GRBs, none of these objections is
really fatal to the scenario. In particular, we show that the total energy
budget of GRBs easily accounts for the energy injection rate necessary to
account for UHECRs as observed at Earth. We also compute the expected particle
spectrum at Earth, showing that it fits the HiRes and AGASA data to within
statistical uncertainties. We consider the existence of multiplets in AGASA'
data. To this end, we present a Langevin--like treatment for the motion of a
charged particle in the IGM magnetic field, which allows us to estimate both
the average and the rms timedelay for particles of given energy; we discuss
when particles of identical energies reach the Earth in bunches, or spread over
the rms timedelay, showing that multiplets pose no problem for an explosive
model for the sources of UHECRs. We compare our model with a scenario where the
particles are accelerated at internal shocks, underlining differences and
advantages of particle acceleration at external shocks.


title:
The correlation of the Lyman-alpha forest in close pairs and groups of
  high-redshift quasars: clustering of matter on scales 1-5 Mpc

abstract:
  We study the clustering of matter in the intergalactic medium from the
Lyman-alpha forests seen in the spectra of pairs or groups of z ~ 2 quasars
observed with FORS2 and UVES at the VLT-UT2 Kueyen ESO telescope. The sample
consists of five pairs with separations 0.6, 1, 2.1, 2.6 and 4.4 arcmin and a
group of four quasars with separations from 2 up to 10 arcmin. This
unprecedented data set allows us to measure the transverse flux correlation
function for a range of angular scales. Correlations are clearly detectable at
separations smaller than 3 arcmin. The shape and correlation length of the
transverse correlation function on these scales is in good agreement with those
expected from absorption by the photoionized warm intergalactic medium
associated with the filamentary and sheet-like structures predicted in CDM-like
models for structure formation. At larger separation no significant correlation
is detected. Assuming that the absorbing structures are randomly orientated
with respect to the line of sight, the comparison of transverse and
longitudinal correlation lengths constrains the cosmological parameters (as a
modified version of the Alcock & Paczy\'nski test). The present sample is too
small to get significant constraints. Using N-body simulations, we investigate
the possibility to constrain Ol from future larger samples of QSO pairs with
similar separations. The observation of a sample of 30 pairs at 2, 4.5 and 7.5
arcmin should constrain the value of Ol at +- 15 % (2 sigma level). We further
use the observed spectra of the group of four quasars, to search for underdense
regions in the intergalactic medium. We find a quasi-spherical structure of
reduced absorption with radius 12.5 h^{-1} Mpc which we identify as an
underdense region.


title:
Spectral and Photometric Evolution of Young Stellar Populations: the
  Impact of Gaseous Emission at Various Metallicities

abstract:
  We include gaseous continuum and line emission into our GALEV models for the
spectral and photometric evolution of Simple Stellar Populations (SSPs) for
various metallicities in the range 0.02 <= Z/Zsun <= 2.5. This allows to extend
them to significantly younger ages than before. They now cover the age range
from 4 Myr all through 14 Gyr. We point out the very important contributions of
gaseous emission to broad band fluxes and their strong metallicity dependence
during very early evolutionary stages of star clusters, galaxies or subgalactic
fragments with vigorous ongoing star formation. Emission-line contributions are
commonly seen in these actively star-forming regions. Models without gaseous
emission cannot explain their observed colors at all, or lead to wrong age
estimates. We use up-to-date Lyman continuum emission rates and decided to use
recent empirical determinations of emission line ratios relative to Hbeta for
subsolar metallicities. We justify this approach for all situations where no or
not enough spectral information is available to determine all the parameters
required by photoionization models. The effects of gaseous line and continuum
emission on broad band fluxes are shown for different metallicities and as a
function of age. In addition to the many filter systems already included in our
earlier models, we here also include the HST NICMOS and Advanced Camera for
Surveys (= ACS) filter systems.


title:
The Absorption and Emission Kinematics in the z=0.7450 Mg II Absorber
  Towards Q1331+17

abstract:
  (Abridged) We present a comparative analysis of the galaxy emission and QSO
absorption kinematics of a z~0.7450 MgII system and its candidate absorbing
galaxy (G5) located 3.86 arcsecs (28.3 h-1 kpc) from the QSO. We have obtained
a spectrum of the galaxy candidate, previously identified as a luminous edge-on
disk, and detect the [OII] 3727 A doublet at a systemic redshift of z =0.7450.
  From slit spectroscopy of this galaxy, we find v_rot ~> 210 km/s, and
possibly as large as 350 km/s. Plotted on the same velocity scale, the systemic
redshift of the galaxy coincides with the center of the absorption system,
although the absorption components span more than 100 km/s in either direction.
However, once the sense of the rotation is taken into account, there is no
absorbing gas at the projected velocity of the disk rotation curve. This
implies incompatibility with a simple disk scenario. Moreover, a re-analysis of
archival HST data reveals that the galaxy is only 0.3 L*, considerably less
luminous than previously reported in the literature. Analysis of the absorption
lines shows evidence for superbubbles in the interstellar medium (ISM) of the
absorbing galaxy, based on the striking symmetry between components and large
MgI/MgII and MgI/FeII ratios, indicative of large densities. The large velocity
separations between line pairings, dv ~ 150 km/s indicates that these bubbles
may be powered by OB associations comparable to the largest observed at z=0 and
that the gas is probably enriched to at least 1/10 solar metallicity.


title: Inflation in Flat Universe

abstract:
  We started the evolution of a flat universe from a nonsingular state called
prematter which is governed by an inflationary equation of state
$P=(\gamma_{p}-1)\rho$ where $\gamma_{p}$ represents the initial vacuum
dominance of the universe. The evolution of the universe-except in the
prematter era-is affected neither by the initial vacuum dominance nor the
initial expansion rate of the universe. On the other hand, present properties
of the universe such as Hubble constant, age and density are sensitive to the
temperature at the decoupling $(T_{m})$. Over a range between $3\cdot10^{4}$
and $5\cdot10^{4}$ K for $(T_{m})$, our model predicts a value between 50 and
80 $Km\cdot sec^{-1}\cdot Mpc^{-1}$ for the present value of the Hubble
constant $(H_{0})$. Assuming that the thermal history of the universe is
independent from its geometry, the above range could be considered as
transition range for the decoupling temperature $(T_{m})$.


title:
Signatures of hadronic cosmic rays in starbursts? High-energy photons
  and neutrinos from NGC253

abstract:
  We show that it appears possible for starburst galaxies, like the nearby NGC
253, recently identified as a TeV source by the CANGAROO collaboration, to emit
a significant amount of high-energy gamma-rays and neutrinos through hadronic
processes in their cores. We suggest that proton illumination of the inner
winds of massive stars can be a viable mechanism for producing TeV gamma-rays
and neutrinos without a strong MeV-GeV counterpart. The rich stellar content of
the starbursts, with millions of early-type stars concentrated in the central
regions, where collective effects of the stellar winds and supernovae can
produce a significant enhancement of the cosmic ray density, provides an
adequate scenario for TeV $\gamma$-ray generation. Close starbursts are also
found to be potential sources for km-scale neutrino telescopes, like ICECUBE,
within reasonable integration times.


title: Curvature force and dark energy

abstract:
  A curvature self-interaction of the cosmic gas is shown to mimic a
cosmological constant or other forms of dark energy, such as a rolling tachyon
condensate or a Chaplygin gas. Any given Hubble rate and deceleration parameter
can be traced back to the action of an effective curvature force on the gas
particles. This force self-consistently reacts back on the cosmological
dynamics. The links between an imperfect fluid description, a kinetic
description with effective antifriction forces, and curvature forces, which
represent a non-minimal coupling of gravity to matter, are established.


title:
Fe K emission and absorption features in XMM-Newton spectra of Mkn 766 -
  evidence for reprocessing in flare ejecta

abstract:
  We report on the analysis of a long XMM-Newton EPIC observation in 2001 May
of the Narrow Line Seyfert 1 galaxy Mkn 766. The 3-11 keV spectrum exhibits a
moderately steep power law continuum, with a broad emission line at ~6.7 keV,
probably blended with a narrow line at ~6.4 keV, and a broad absorption trough
above ~8.7 keV. We identify both broad spectral features with reprocessing in
He-like Fe. An earlier XMM-Newton observation of Mkn 766 in 2000 May, when the
source was a factor ~2 fainter, shows a similar broad emission line, but with a
slightly flatter power law and absorption at a lower energy. In neither
observation do we find a requirement for the previously reported broad 'red
wing' to the line and hence of reflection from the innermost accretion disc.
More detailed examination of the longer XMM-Newton observation reveals evidence
for rapid spectral variability in the Fe K band, apparently linked with the
occurrence of X-ray 'flares'. A reduction in the emission line strength and
increased high energy absorption during the X-ray flaring suggests that these
transient effects are due to highly ionised ejecta associated with the flares.
Simple scaling from the flare avalanche model proposed for the luminous QSO PDS
456 (Reeves etal. 2002) confirms the feasibility of coherent flaring being the
cause of the strong peaks seen in the X-ray light curve of \mkn.


title: Optical and Far-UV Spectroscopy of Knot D in the Vela Supernova Remnant

abstract:
  We present spectra of optical filaments associated with the X-ray knot D in
the Vela supernova remnant. It has been suggested that Knot D is formed by a
bullet of supernova ejecta, that it is a break-out of the shock front of the
Vela SNR, and also that it is an outflow from the recently discovered remnant
RXJ0852.0-4622. We find that Knot D is a bow shock propagating into an
interstellar cloud with normal abundances and typical cloud densities (n_H ~
4-11 cm^-3). Optical longslit spectra show that the [S II] 6716,6731 to Halpha
line ratio is greater than unity, proving that the optical filaments are shock
excited. The analysis of far-ultraviolet spectra obtained with the Hopkins
Ultraviolet Telescope and with the Far Ultraviolet Spectroscopic Explorer
(FUSE) LWRS aperture show that slower shocks (~100 km s^-1) produce most of the
low ionization lines such as O III] 1662, while faster shocks (~180 km s^-1)
produce the O VI 1032,1038 and other high ionization lines. C III and O VI
lines are also detected in the FUSE MDRS aperture, which was located on an
X-ray bright region away from the optical filaments. The lines have two
velocity components consistent with ~150 km s^-1 shocks on the near and far
sides of the knot. The driving pressure in the X-ray knot, P/k ~ 1.8E+7 cm^-3
K, is derived from the shock properties. This is over an order of magnitude
larger than the characteristic X-ray pressure in the Vela SNR. The velocity
distribution of the emission and the overpressure support the idea that Knot D
is a bow shock around a bullet or cloud that originated near the center of the
Vela remnant.


title: Fireballs, Flares and Flickering

abstract:
  We review our understanding of the prototype ``Propeller'' system AE Aqr and
we examine its flaring behaviour in detail. The flares are thought to arise
from collisions between high density regions in the material expelled from the
system after interaction with the rapidly rotating magnetosphere of the white
dwarf. We show calculations of the time-dependent emergent optical spectra from
the resulting hot, expanding ball of gas and derive values for the mass,
lengthscale and temperature of the material involved. We see that the fits
suggest that the secondary star in this system has reduced metal abundances and
that, counter-intuitively, the evolution of the fireballs is best modelled as
isothermal.


title:
CO emission and associated HI absorption from a massive gas reservoir
  surrounding the z=3 radio galaxy B3 J2330+3927

abstract:
  We present results of a comprehensive multi-frequency study of the radio
galaxy B3 J2330+3927. The 1.9" wide radio source, consisting of 3 components,
is bracketed by 2 objects in our Keck K-band image. Optical and near-IR Keck
spectroscopy of these two objects yield z=3.087+-0.004. The brightest (K=18.8)
object has a standard type II AGN spectrum, and is the most likely location of
the AGN, which implies a one-sided jet radio morphology. Deep 113 GHz
observations with the IRAM Plateau de Bure Interferometer reveal CO J=4-3
emission, which peaks at the position of the AGN. The CO line is offset by 500
km/s from the systemic redshift of the AGN, but corresponds very closely to the
velocity shift of an associated HI absorber seen in Lya. This strongly suggests
that both originate from the same gas reservoir surrounding the AGN host
galaxy. Simultaneous 230 GHz interferometer observations find a ~3x lower
integrated flux density when compared to single dish 250 GHz observations with
MAMBO at the IRAM 30m telescope. This can be interpreted as spatially resolved
thermal dust emission at scales of 0.5" to 6". Finally, we present a tau <1.3%
limit to the HI 21 cm absorption against the radio source, which represents the
seventh non-detection out of 8 z>2 radio galaxies observed to date with the
WSRT. We present mass estimates for the atomic, neutral, and ionized hydrogen,
and for the dust, ranging from M(HI)=2x10^7 M_Sun derived from the associated
HI absorber in Lya up to M(H_2)=7x10^{10} M_Sun derived from the CO emission.
This indicates that the host galaxy is surrounded by a massive reservoir of gas
and dust. The K-band companion objects may be concentrations within this
reservoir, which will eventually merge with the central galaxy hosting the AGN.


title: Is the Giant Radio Galaxy M87 a TeV Gamma-Ray Emitter?

abstract:
  For the first time an excess of photons above an energy threshold of 730 GeV
from the giant radio galaxy M87 has been measured at a significance level above
4 sigma. The data have been taken during the years 1998 and 1999 with the HEGRA
stereoscopic system of 5 imaging atmospheric Cherenkov telescopes. The excess
of 107.4 +- 26.8 events above 730 GeV corresponds to an integral flux of 3.3%
of the Crab flux or N_gamma(E > 730 GeV) = (0.96 +- 0.23) * 10^(-12)
phot.cm^(-2)s^(-1). M87 is located at the center of the Virgo cluster of
galaxies at a relatively small redshift of z = 0.00436 and is a promising
candidate among the class of giant radio galaxies for the emission of TeV
gamma-radiation. The detection of TeV gamma-rays from M87 -- if confirmed --
would establish a new class of extragalactic source in this energy regime since
all other AGN detected to date at TeV energies are BL Lac type objects.


title:
Matter and Radiation in Superstrong Magnetic Fields and Thermal Emission
  from Neutron Stars

abstract:
  Thermal surface emissions have now been detected from more than a dozen
isolated neutron stars, including radio pulsars, radio-quiet neutron stars and
magnetars. These detections can potentially provide important information on
the interior physics, magnetic fields, and surface composition of neutron
stars. Understanding the properties of matter and radiative transfer in strong
magnetic fields is essential for the proper interpretation of the observations.
We review current theoretical works on modeling magnetized neutron star
atmospheres/surface layers, discussing some of the novel properties of matter
and radiative transfer in strong magnetic fields. Of particular interest is the
effect of the strong-field vacuum polarization, which dramatically changes the
radiative transfer and the emergent X-ray spectra from magnetars.


title: Spectral Energy Distributions of Dusty Galaxies

abstract:
  We present a SED model of dusty galaxies, in which the equation of radiative
transfer is solved by assuming spherical symmetry. The temperature fluctuation
of very small dust particles is calculated consistently with the radiative
transfer. The adopted dust model consists of graphite and silicate grains and
PAHs, whose relative fractions are determined for each MW, LMC and SMC type
extinction curve. This model allows us to derive the intrinsic SEDs of stellar
populations embedded in dusty ISM, which are very important indicators for the
age of stellar populations. Therefore, the evolutionary phase of starburst
galaxies which have frequently very dusty ISM can be investigated with this SED
model. We show that the SEDs of Arp220 and M82 can both be explained by the
same single stellar population, despite the significant differences in the SEDs
and the infrared luminosities. The apparent difference between their SEDs is
mainly caused by the difference in the optical depth. In contrast, the SED of
prototypical star-forming ERO, HR10, indicates that this galaxy is relatively
old comparing to Arp220 and M82. It is found that, in the case of optically
thin limit like elliptical galaxies, the optical depth cannot be inferred only
from the SED, due to a degeneracy between the optical depth, galactic size, and
the spatial distribution of dust; the latter two are important for estimating
the average temperature of dust grains in elliptical galaxies. When the
observed size of elliptical galaxies is adopted for the model geometry, SEDs
can be used to constrain the spatial distribution of dust in elliptical
galaxies.


title: The CNO problem in magnetic cataclysmic variables

abstract:
  Some magnetic CVs like BY Cam are characterized by unusual CNO line ratios
compared to other polars and non-solar abundances have been suggested to
explain this anomaly. We present here a first attempt to constrain the
elemental abundances in these systems by applying a specific ionisation model
combined with a geometrical description of the accretion column where these
lines are thought to be formed. The line luminosities have been computed using
the CLOUDY plasma code for different ionisation spectra and column extension.
We show here selected results and compare to the values observed in "peculiar"
magnetic CVs. The model applied to BY Cam confirms that ionization models with
solar abundances fail to reproduce the observed line intensity ratios. Assuming
the model to be valid, the induced best abundances imply an overabundance of N
(x25), underabundance of C (:8) and nearly solar O (:2), in line with CNO
reprocessing.


title: MAXIMA: Observations of CMB Anisotropy

abstract:
  This document describes the Millimeter Anisotropy eXperiment IMaging Array
(MAXIMA), a balloon-borne experiment measuring the temperature anisotropy of
the Cosmic Microwave Background (CMB) on angular scales of 10 arcminutes to 5
degrees. MAXIMA maps the CMB using 16 bolometric detectors observing in
spectral bands centered at 150 GHz, 230 GHz, and 410 GHz, with 10 arcminute
resolution at all frequencies. The combined receiver sensitivity to CMB
anisotropy is 40 micro-K*(sec^0.5). During two flights with a total of 8.5
hours of CMB observations, 300 square degrees of the sky were mapped. MAXIMA
data are used to discriminate between cosmological models and to determine
cosmological parameters; results are presented from the 1998 flight. The
angular power spectrum derived from these data shows a narrow peak near l=200,
and is consistent with inflationary Big Bang models. Cosmological parameters
are estimated, including total density Omega(total)=0.9(-0.16,+0.18), baryon
density Omega(b)h^2=0.033(+/-0.013), and power spectrum normalization
C(10)=690(-125,+200) micro-K^2. The final chapter is a discussion CMB
polarization anisotropy, including an overview of MAXIPOL, the polarization
sensitive follow-up to MAXIMA.


title: Occultation Searches for Kuiper Belt Objects

abstract:
  The occultation of background stellar sources by foreground Kuiper Belt
Objects (KBOs) can be used to survey physical properties of the KBO population.
We discuss statistics related to a KBO occultation survey, such as the event
duration distribution, and suggest that occultation searches can be effectively
used to probe the KBO size distribution below 10 km. In particular, we suggest
that occultation surveys may be best suited to search for a turnover radius in
the KBO size distribution due to collisions between small-size objects. For
occultation surveys that monitor stellar sources near the ecliptic over a few
square degrees, with time sampling intervals of order 0.1 sec and sensitivity
to flux variations of a few percent or more, a turnover radius between 0.1 and
1.0 km can be probed. While occultation surveys will probe the low-radius limit
and imaging surveys will detect KBOs of size 100 km or more, statistics of
objects with sizes in the intermediate range of around 1 km to 100 km will
likely remain unattainable.


title: Virial shocks in galactic haloes?

abstract:
  We investigate the conditions for the existence of an expanding virial shock
in the gas falling within a spherical dark-matter halo. The shock relies on
pressure support by the shock-heated gas behind it. When the radiative cooling
is efficient compared to the infall rate the post-shock gas becomes unstable;
it collapses inwards and cannot support the shock.
  We find for a monoatomic gas that the shock is stable when the post-shock
pressure and density obey gamma effective>10/7, with gamma effective begin the
time depended equivalent to the adiabatic index. We express the effective gamma
in terms of r, u and rho at the shock to obtain a simple condition for shock
stability. This result is confirmed by hydrodynamical simulations, using an
accurate spheri-symmetric Lagrangian code. When the stability analysis is
applied in cosmology, we find that a virial shock does not develop in most
haloes that form before z ~ 2, and it never forms in haloes less massive than a
few 10^11 solar masses. In such haloes the infalling gas is never heated to the
virial temperature, and it does not need to cool radiatively before it drops
into a disc. Instead, the gas collapses at T ~ 10^4K directly into the disc.
This should have nontrivial effects on the star-formation rate and on the gas
removal by supernova-driven winds. Instead of radiating soft x rays, this gas
would emit lyman alpha thus helping explain the low flux of soft x-ray
background and the lyman alpha emitters observed at high redshift.


title: Strong magnetic fields and cosmic rays in very young galaxies

abstract:
  We present a scenario for efficient magnetization of very young galaxies
about 0.5 Gigayears after the Big-Bang by a cosmic ray-driven dynamo. These
objects experience a phase of strong star formation during this first $10^9$
years. We transfer the knowledge of the connection between star formation and
the production rate of cosmic rays by supernova remnants to such high redshift
objects. Since the supernova rate is a direct measure for the production rate
of cosmic rays we conclude that very young galaxies must be strong sources of
cosmic rays. The key argument of our model is the finding that magnetic fields
and cosmic rays are dynamically coupled, i.e. a strong cosmic ray source
contains strong magnetic fields since the relativistic particles drive an
efficient dynamo in a galaxy via their buoyancy. We construct a
phenomenological model of a dynamo driven by buoyancy of cosmic rays and show
that if azimuthal shearing is strong enough the dynamo amplification timescale
is close to the buoyancy timescale of the order of several $10^7 \div 10^8$ yr.
We predict that young galaxies are strongly magnetized and may contribute
significantly to the gamma-ray-background.


title:
Review of Discrete X-Ray Sources in the Small Magellanic Cloud: Summary
  of the ASCA Results and Implication on the Recent Star Forming Activity

abstract:
  We made 22 observations on the Small Magellanic Cloud (SMC) and covered full
regions by the end of the ASCA mission. We detected 106 discrete sources with a
criterion of S/N > 5 and performed systematic analyses on all of the sources.
We determined the source positions with an ~40'' error radius (90% confidence)
for sources detected in the central 20' radius of the GIS. We detected coherent
pulsations from 17 sources. Among them, eight were newly discovered during this
study. We classified most of these pulsars as X-ray binary pulsars (XBPs) based
on their properties, such as the flux variability and the existence of an
optical counterpart. We detected X-ray emission from eight supernova remnants
(SNRs). Among them, five SNRs showed emission lines in their spectra, hence we
regarded the five as thermal SNRs. We found that XBPs and thermal SNRs in the
SMC can be clearly separated by their spectral hardness ratio. Applying this
empirical law to faint (thus unclassified) sources, we found 19 XBP candidates
and four thermal SNR candidates. We also found several tens of candidates for
active galactic nuclei, both from the hardness ratio and the logN--logS
relation of extragalactic sources. Based on these ASCA results and further
information from other sattelites, we compiled comprehensive catalogues of
discrete X-ray sources in the Small Magellanic Cloud. Using the catalogues, we
derived the spatial distributions of XBPs and SNRs. XBPs and SNRs were found to
be concentrated in the main body and eastern wing, which resembles the
distribution of young stars with ages of ~2e7yr. By comparing the source
populations in the SMC and our Galaxy, we suggest that the star-forming rate
(per unit mass) in the SMC was much higher than the Galaxy 1e7yr ago. We also
discuss the recent change of the star-forming rate in the SMC.


title: The mineralogy, geometry and mass-loss history of IRAS 16342-3814

abstract:
  We present the 2-200 um Infrared Space Observatory (ISO) spectrum and 3.8-20
um ISAAC and TIMMI2 images of the extreme OH/IR star IRAS 16342-3814. Amorphous
silicate absorption features are seen, together with crystalline silicate
absorption features up to almost 45 um. No other OH/IR star is known to have
crystalline silicate features in absorption up to these wavelengths. This
suggests that IRAS 16342-3814 must have, or recently had, an extremely high
mass-loss rate. Preliminary radiative transfer calculations suggest that the
mass-loss rate may be as large as 10^{-3} Msun/yr. The 3.8 um ISAAC image shows
a bipolar reflection nebula with a dark equatorial waist or torus, similar to
that seen in optical Hubble Space Telescope (HST) images. The position angle of
the nebula decreases significantly with increasing wavelength, suggesting that
the dominant source of emission changes from scattering to thermal emission.
Still, even up to 20 um the nebula is oriented approximately along the major
axis of the nebula seen in the HST and ISAAC images, suggesting that the torus
must be very cold, in agreement with the very red ISO spectrum. The 20 um image
shows a roughly spherically symmetric extended halo, approximately 6'' in
diameter, which is probably due to a previous phase of mass-loss on the AGB,
suggesting a transition from a (more) spherically symmetric to a (more) axial
symmetric form of mass-loss at the end of the AGB. We estimate the maximum dust
particle sizes in the torus and in the reflection nebula to be 1.3 and 0.09 um
respectively. The size of the particles in the torus is large compared to
typical ISM values, but in agreement with high mass-loss rate objects like AFGL
4106 and HD161796. We discuss the possible reason for the difference in
particle size between the torus and the reflection nebula.


title: Solid Quark Stars?

abstract:
  It is conjectured that cold quark matter with much high baryon density could
be in a solid state, and strange stars with low temperatures should thus be
solid stars. The speculation could be close to the truth if no peculiar
polarization of thermal X-ray emission (in, e.g., RXJ1856), or no gravitational
wave in post-glitch phases, is detected in future advanced facilities, or if
spin frequencies beyond the critical ones limited by r-mode instability are
discovered. The shear modulus of solid quark matter could be ~ 10^{32} erg/cm^3
if the kHz QPOs observed are relevant to the eigenvalues of the center star
oscillations.


title:
Large Angle CMB Fluctuations from Cosmic Strings with a Comological
  Constant

abstract:
  In this paper, we present results for large-angle CMB anisotropies generated
from high resolution simulations of cosmic string networks in a range of flat
FRW universes with a cosmological constant. Using an ensemble of all-sky maps,
we compare with the COBE data to infer a normalization (or upper bound) on the
string linear energy density $\mu$. For a flat matter-dominated model
($\Omega_{M}=1$) we find $G\mu/c^2 \approx 0.7\times 10^{-6}$, which is lower
than previous constraints probably because of the more accurate inclusion of
string small-scale structure. For a cosmological constant within an
observationally acceptable range, we find a relatively weak dependence with
$G\mu/c^2$ less than 10% higher.


title: Inverse Power Law Quintessence with Non-Tracking Initial Conditions

abstract:
  A common property of popular models of quintessence dark energy is the
convergence to a common solution from a large range of the initial conditions.
We re-examine the popular inverse power-law model of quintessence (where the
common solution is dubbed as the 'tracker') with particular attention to the
initial conditions for the field and their influence on the evolution. We find
that previously derived limits on the parameters of the potential in this model
are valid only in a range of initial conditions. A reasonably sharp boundary
lies where the initial energy density of the scalar field is equal to that of
the background radiation component. An initial quintessence energy density
above this equipartition value lead to a solution that will not have joined the
tracker solution by the present epoch. These non-tracker solutions possess the
property that their present equation of state is very compatible with the
observed bounds and independent of the exponent of the potential.


title: Origin of Cosmic Magnetic Fields

abstract:
  We propose that the overlapping shock fronts from young supernova remnants
produce a locally unsteady, but globally steady large scale spiral shock front
in spiral galaxies, where star formation and therefore massive star explosions
correlate geometrically with spiral structure. This global shock front with its
steep gradients in temperature, pressure and associated electric fields will
produce drifts, which in turn give rise to a strong sheet-like electric
current, we propose. This sheet current then produces a large scale magnetic
field, which is regular, and connected to the overall spiral structure. This
rejuvenates the overall magnetic field continuously, and also allows to
understand that there is a regular field at all in disk galaxies. This proposal
connects the existence of magnetic fields to accretion in disks. We not yet
address all the symmetries of the magnetic field here; the picture proposed
here is not complete. X-ray observations may be able to test it already.


title: Transition from L to T Dwarfs on the Color-Magnitude Diagram

abstract:
  The color-magnitude (CM) diagram of cool dwarfs and brown dwarfs based on the
recent astrometry data is compared with the CM diagram transformed from the
theoretical evolutionary tracks via the unified cloudy models (UCMs) of L and T
dwarfs. A reasonable agreement between the models and observations is shown for
the whole regime of ultracool dwarfs covering L and T dwarfs, and this is
achieved, for the first time, with the use of a single grid of self-consistent
nongray model photospheres accommodating dust cloud (UCMs with T_eff between
700 and 2600 K). A distinct brightening at the J band in the early T dwarfs
revealed by the recent parallax measurements is explained as a natural
consequence of the migration of the thin dust cloud to the inner region of the
photosphere and should not necessarily be evidence for Burgasser et al.'s
proposition that the dust cloud breaks up in the L/T dwarf transition. Also,
the rapid bluing from the late L to the early T dwarfs is a direct result of
the transition of the thin dust cloud from the optically thin (tau < 1) to
thick (tau > 1) regimes while L_bol and T_eff} lower only slightly. Thus, the
theoretical evolutionary models, the cloudy models of the photospheres (UCMs),
and the observed fundamental stellar parameters aqre brought into a consistent
picture of the newly defined L and T dwarfs.


title: Using radio galaxies to find super-structures

abstract:
  Radio galaxies are excellent at tracing large-scale structure due to their
high bias. We present new results from the TONS08 radio galaxy redshift survey.
We find unequivocal evidence for a huge (at least 80 x 80 x 100 Mpc^3)
super-structure at redshift z=0.27, confirming tentative evidence for such a
structure from the 7C redshift survey (7CRS). A second, newly discovered
super-structure is also tentatively found at redshift 0.35 (of dimensions at
least 100 x 100 x 100 Mpc^3). Out of the total sample size of 84 radio
galaxies, at least 25 are associated with the two super-structures. We use
quasi-linear structure formation theory to estimate the number of such
structures expected in the TONS08 volume if the canonical value for radio
galaxy bias is assumed. Under this assumption, the structures represent ~ 4-5
sigma peaks in the primordial density field and their expected number is low
(10^{-2}-10^{-4}). Fortunately, there are several plausible explanations (many
of which are testable) for these low probabilities in the form of potential
mechanisms for boosting the bias on large scales. These include: the
association of radio galaxies with highly biased rich clusters in
super-structures, enhanced triggering by group/group mergers, and enhanced
triggering and/or redshift space distortion in collapsing systems as the growth
of super-structures moves into the non-linear regime. Similar structures could
have been missed in previous surveys because of the effects of Poisson-sampling
fluctuations.


title: BAX: A dedicated X-Rays galaxy clusters Database

abstract:
  We present BAX, Base de Donn\'ees amas de galaxies X
(http://webast.ast.obs-mip.fr/bax), a project aiming at building a
comprehensive database dedicated to X-rays clusters of galaxies allowing
detailed information retrieval. BAX provides the user with {\it basic data}
published in the literature on X-rays clusters of galaxies as well as with
information concerning the physical properties in the X-rays domain or at other
wavelengths. BAX allows individual studies on selected clusters as well as
building up homogenous samples, from known X-rays clusters for which selection
criteria are chosen through web interfaces. We expect BAX to become a useful
tool for astronomy community in order to optimize the cluster science return
using data from both ground based facilities like MEGACAM (CFHT), VIRMOS (VLT)
and space missions like XMM, Chandra and Planck.


title:
General solution of the Jeans equations for triaxial galaxies with
  separable potentials

abstract:
  The Jeans equations relate the second-order velocity moments to the density
and potential of a stellar system. For general three-dimensional stellar
systems, there are three equations and six independent moments. By assuming
that the potential is triaxial and of separable Staeckel form, the mixed
moments vanish in confocal ellipsoidal coordinates. Consequently, the three
Jeans equations and three remaining non-vanishing moments form a closed system
of three highly-symmetric coupled first-order partial differential equations in
three variables. These equations were first derived by Lynden-Bell, over 40
years ago, but have resisted solution by standard methods. We present the
general solution here.
  We consider the two-dimensional limiting cases first. We solve their Jeans
equations by a new method which superposes singular solutions. The singular
solutions, which are new, are standard Riemann-Green functions. The
two-dimensional solutions are applied to non-axisymmetric discs, oblate and
prolate spheroids, and also to the scale-free triaxial limit. We then extend
the method of singular solutions to the triaxial case, and obtain a full
solution. The general solution can be expressed in terms of complete
(hyper)elliptic integrals which can be evaluated in a straightforward way, and
provides the full set of second moments which can support a triaxial density
distribution in a separable triaxial potential. (abridged)


title: On the nature of mass-energy constituents of the universe

abstract:
  On the basis of our quantum cosmological approach we show that there can be
two previously unknown types of collective states in the universe. One of them
relates to a gravitational field, another is connected with a matter (scalar)
field which fills the universe on all stages of its evolution. The increase in
number of the quanta of the collective excitations of the gravitational field
manifests itself as an expansion of the universe. The collective excitations of
the scalar field above its true vacuum reveal themselves mainly in the form of
dark matter and energy. Under the action of the gravitational forces they decay
and produce the non-baryonic dark matter, optically bright and dark baryons. We
have calculated the corresponding energy densities which prove to be in good
agreement with the data from the recent observations.


title: Fine Structures of Shock of SN 1006 with the Chandra Observation

abstract:
  The north east shell of SN 1006 is the most probable acceleration site of
high energy electrons (up to ~ 100 TeV) with the Fermi acceleration mechanism
at the shock front. We resolved non-thermal filaments from thermal emission in
the shell with the excellent spatial resolution of Chandra. The thermal
component is extended widely over about ~ 100 arcsec (about 1 pc at 1.8 kpc
distance) in width, consistent with the shock width derived from the Sedov
solution. The spectrum is fitted with a thin thermal plasma of kT = 0.24 keV in
non-equilibrium ionization (NEI), typical for a young SNR. The non-thermal
filaments are likely thin sheets with the scale widths of ~ 4 arcsec (0.04 pc)
and ~ 20 arcsec (0.2 pc) at upstream and downstream, respectively. The spectra
of the filaments are fitted with a power-law function of index 2.1--2.3, with
no significant variation from position to position. In a standard diffusive
shock acceleration (DSA) model, the extremely small scale length in upstream
requires the magnetic field nearly perpendicular to the shock normal. The
injection efficiency (eta) from thermal to non-thermal electrons around the
shock front is estimated to be ~ 1e-3 under the assumption that the magnetic
field in upstream is 10 micro G. In the filaments, the energy densities of the
magnetic field and non-thermal electrons are similar to each other, and both
are slightly smaller than that of thermal electrons. in the same order for each
other. These results suggest that the acceleration occur in more compact region
with larger efficiency than previous studies.


title: Ellipsoidal Variability in the OGLE Planetary Transit Candidates

abstract:
  We analyze the photometry of 117 OGLE stars with periodic transit events for
the presence of ellipsoidal light variations, which indicate the presence of
massive companions. We find that ~50% of objects may have stellar companions,
mostly among the short period systems. In our Table 1 we identify a coefficient
of ellipsoidal variability for each star, a_{c2}, which can be used to select
prime candidates for planetary searches. There is a prospect of improving the
analysis, and the systems with smaller ellipsoidal variability will be
identified, when the correlations in the OGLE photometry are corrected for in
the future, thereby providing a cleaner list of systems with possible planets.


title: The Radio Jet Velocities at High Resolution

abstract:
  The different methods to derive the jet velocity and orientation on the
parsec scale are presented. From these methods I will discuss the velocity
distribution of parsec scale jets and the possible presence of acceleration or
deceleration in the jet velocity. Moreover, evidences of jet velocity
structures will be reported. Finally I will present new data on the
superluminal giant radio source 1144+35 to discuss in detail the properties of
pc scale jets.


title: Polarization in GRB Afterglows

abstract:
  Polarization has been observed in a number of GRB afterglows. We briefly
review the models that have been proposed to account for the observed
polarization levels. We summarize the observations and the attempts to explain
them with existing models.


title:
ISOCAM-CVF spectroscopy of the circumstellar environment of young
  stellar objects

abstract:
  We present the results of a mid-infrared imaging spectroscopy survey of Young
Stellar Objects (YSOs) and their surrounding environment in four low-mass star
formation regions: RCrA, Rho Ophiuchi, Serpens and Chamaeleon I. This survey
was performed using ISOCAM and its Circular Variable Filters (CVF) and observed
42 YSO candidates. A number of spectral features were measured, most notably
the 9.7um silicate feature, the bending modes of both water and CO2 ices at 6.0
and 15.2um respectively and the well-known unidentified feature at 6.8um. The
strength of the unidentified feature was observed to correlate very well with
that of the water ice bending mode and far less strongly with the CO2 ice
bending mode. This suggests, in a manner consistent with previous observations,
that the carrier of the unidentified feature is a strongly polar ice.
Absorption profiles of the bending mode of CO2 ice are observed to show a
significant long wavelength wing, which suggests that a significant fraction of
the CO2 ice observed exists in a polar (H2O-rich) phase. The sources observed
in RCrA, Rho Oph and Serpens show similar spectral characteristics, whilst the
sources observed in Cha I are somewhat anomalous. However this is consistent
with previous studies of this region of the Cha I cloud, which contains an
unusual cluster of YSOs. We detect an apparent under-abundance of water ice
towards the sources in Rho Oph. This may be indicative of differences in
chemical composition between the different clouds, or may be due to
evaporation. Finally the CO2:H2O ice ratios observed towards the sources in Rho
Oph show significantly greater scatter than in the other regions, possibly due
to varying local conditions around the YSOs in Rho Oph. (Abridged)


title:
`Thermal' SiO radio line emission towards M-type AGB stars: a probe of
  circumstellar dust formation and dynamics

abstract:
  An extensive radiative transfer analysis of circumstellar SiO `thermal' radio
line emission from a large sample of M-type AGB stars has been performed. The
sample contains 18 irregulars of type Lb (IRV), 7 and 34 semiregulars of type
SRa and SRb (SRV), respectively, and 12 Miras. New observational material,
which contains data in several SiO rotational lines in the ground vibrational
state, is presented for the IRV/SRVs. The detection rate was about 60%. SiO
fractional abundances have been determined through radiative transfer
modelling. The abundance distribution of the IRV/SRV sample has a median value
of 8E-6. The high mass loss rate Miras have a bimodal abundance distribution, a
low abundance group (on average 4E-7) and a high abundance group (on average
7E-6). The derived SiO abundances are in all cases well below the abundance
expected from stellar atmosphere chemistry, on average by a factor of ten. In
addition, there is a trend of decreasing SiO abundance with increasing mass
loss rate. This is interpreted in terms of depletion of SiO molecules by the
formation of silicate grains in the circumstellar envelopes, with an efficiency
which increases with the mass loss rate. The SiO and CO radio line profiles
differ in shape. In general, the dominating part of the SiO profiles are
narrower than the CO profiles, but they have low-intensity wings which cover
the full velocity range of the CO profile. This is interpreted (as has been
done also by others) as due to the influence of gas acceleration in the region
which produces a significant fraction of the SiO line emission. Finally, a
number of sources which have peculiar CO line profiles are discussed from the
point of view of their SiO line properties.


title: Using bright ellipticals as dark energy cosmic clocks

abstract:
  The age of the Universe has been increasingly constrained by different
techniques such as the observations of type Ia supernovae at high redshift or
dating the stellar populations of globular clusters. In this paper we present a
complementary approach using the colours of the brightest elliptical galaxies
in clusters over a wide redshift range (z<1). We put new and independent bounds
on the dark energy equation of state parameterised by a constant
pressure-to-density ratio as well as by a parameter which determines the
scaling between the matter and dark energy densities. We find that accurate
estimates of the metallicities of the stellar populations in moderate and high
redshift cluster galaxies can pose stringent constraints on the parameters
which describe the dark energy equation of state. Our results are in good
agreement with the analysis of dark energy models using SNIa data as
constraint. Accurate estimates of the metallicities of stellar populations in
cluster galaxies at z<2 will make this approach a powerful complement to
studies of cosmological parameters using high redshift SNIa.


title: Reappraising foreground contamination in the COBE-DMR data

abstract:
  With the advent of all-sky H-Alpha surveys it is possible to determine a
reliable free-free template of the diffuse interstellar medium (Dickinson,
Davies & Davis 2003) which can be used in conjunction with the synchrotron and
dust templates to correct CMB observations for diffuse Galactic foregrounds. We
have used the COBE-DMR data at 31.5, 53 and 90 GHz and employed cross-
correlation techniques to re-evaluate the foreground contributions,
particularly that due to dust which is known to be correlated with H-Alpha (and
free-free) emission.The DMR microwave maps are found to contain, as well as the
expected synchrotron and free-free components, a component tightly correlated
to the 140 micron dust maps of DIRBE. At 31.5, 53 and 90 GHz this emission is
6.3 +/- 0.6, 2.4 +/- 0.4 and 2.2 +/- 0.4 microK/(MJy/sr) at 140 microns
respectively. When corrected for the contribution from thermal dust following
model 7 of Finkbeiner, Davis & Schlegel (1999), a strong anomalous dust
emission component remains, which is well-fitted by a frequency spectrum of the
form $\nu^{-\beta}$ where beta ~ 2.5 in the DMR frequency range; this is the
dominant foreground at 31.5 GHz. The result implies the presence of an emission
component with a dust-like morphology but a synchrotron-like spectrum. We
discuss the possible origins of this component and compare it with the recent
WMAP interpretation. The better knowledge of the individual foregrounds
provided by the present study enables a larger area of the sky (|b|>15) to be
used to re-appraise the CMB quadrupole normalisation, Qrms-PS, and the scalar
perturbations spectral index, n. We find Qrms-PS=15.2^{+2.8}_{-2.3} with a
power-law spectral index of n=1.2 +/- 0.2. These values are consistent with
previous COBE-DMR analyses and the WMAP 1-year analysis.


title: Radio Emission from an Ultraluminous X-Ray Source

abstract:
  The physical nature of ultraluminous x-ray sources is uncertain. Stellar mass
black holes with beamed radiation and intermediate mass black holes with
isotropic radiation are two plausible explanations. We discovered radio
emission from an ultraluminous x-ray source in the dwarf irregular galaxy NGC
5408. The x-ray, radio and optical fluxes as well as the x-ray spectral shape
are consistent with beamed relativistic jet emission from an accreting stellar
black hole. If confirmed, this would suggest that the ultraluminous x-ray
sources may be stellar-mass rather than intermediate mass black holes. However,
interpretation of the source as a jet-producing intermediate-mass black hole
cannot be ruled out at this time.


title:
Non-linear resonance in nearly geodesic motion in low-mass X-ray
  binaries

abstract:
  We have explored the ideas that parametric resonance affects nearly geodesic
motion around a black hole or a neutron star, and that it may be relevant to
the high frequency (twin) quasi-periodic oscillations occurring in some
low-mass X-ray binaries. We have assumed the particles or fluid elements of an
accretion disc to be subject to an isotropic perturbation of a hypothetical but
rather general form. We find that the parametric resonance is indeed excited
close to the radius where epicyclic frequencies of radial and meridional
oscillations are in a 2:3 ratio. The location and frequencies of the highest
amplitude excitation vary with the strength of the perturbation. These results
agree with actual frequency ratios of twin kHz QPOs that have been reported in
some black hole candidates, and they may be consistent also with correlation of
the twin peaks in Sco X-1.


title: The Discovery of Submillimeter Galaxies

abstract:
  I briefly describe some results about luminous distant dusty galaxies
obtained in the 5 years since sensitive two-dimensional bolometer array cameras
became available. The key requirements for making additional progress in
understanding the properties of these galaxies are discussed, especially the
potential role of photometric redshifts based on radio, submillimeter and
far-infrared continuum observations.


title: Radio relics in a cosmological cluster merger simulation

abstract:
  Motivated by the discovery of a number of radio relics we investigate the
fate of fossil radio plasma during a merger of clusters of galaxies using
cosmological smoothed-particle hydrodynamics simulations. Radio relics are
extended, steep-spectrum radio sources that do not seem to be associated with a
host galaxy. One proposed scenario whereby these relics form is through the
compression of fossil radio plasma during a merger between clusters. The
ensuing compression of the plasma can lead to a substantial increase in
synchrotron luminosity and this appears as a radio relic. Our simulations show
that relics are most likely to be found at the periphery of the cluster at the
positions of the outgoing merger shock waves. Relics are expected to be very
rare in the centre of the cluster where the life time of relativistic electrons
is short and shock waves are weaker than in the cooler, peripheral regions of
the cluster. These predictions can soon be tested with upcoming low-frequency
radio telescopes.


title:
Pressure Balance between Thermal and Non-Thermal Plasmas in the 3C129
  Cluster

abstract:
  With new Chandra observations of the cluster containing the two radio
galaxies 3C129 and 3C129.1, we have made a fit to the X-ray surface brightness
to obtain thermal pressures. VLA data at 1.4 GHz have been obtained to
complement previous maps at 0.33 GHz and at 5 and 8 GHz. From these radio data,
we are able to derive the minimum non-thermal pressure of various emitting
volumes along the tail of 3C129 and in the lobes of 3C129.1. Under the
assumption that the non-thermal plasma excludes significant thermal plasma, we
may expect pressure balance for most features since ram pressure should be
important only close to the cores of the galaxies. Since we find that the
minimum non-thermal pressures are generally only a factor of a few below
estimates of the ambient thermal pressure, we conclude that it is unlikely that
relativistic protons contribute significantly to the total pressure. Reasonable
contributions from low energy electrons and filling factors in the range 0.1 to
1 suffice to achieve pressure balance. Although we do not find strong
signatures for the exclusion of hot gas from the radio structures, we find soft
features near the cores of both galaxies suggestive of cool gas stripping and
hard features associated with radio jets and possibly a leading bow shock.


title:
Abundance of damped Lyman-alpha absorbers in cosmological SPH
  simulations

abstract:
  We use cosmological smoothed-particle hydrodynamics (SPH) simulations of the
Lambda cold dark matter (CDM) model to study the abundance of damped
Lyman-alpha absorbers (DLAs) in the redshift range z=0-4.5. We compute the
cumulative DLA abundance by using the relation between DLA cross-section and
the total halo mass inferred from the simulations. Our approach includes a
phenomenological model of galactic wind. We employ the ``conservative entropy''
formulation of SPH, and utilise a series of simulations of varying box-size and
particle number to isolate the impact of numerical resolution on our results.
We show that the DLA abundance was overestimated in previous studies for three
reasons: (1) the overcooling of gas occurring with non-conservative
formulations of SPH, (2) a lack of numerical resolution, and (3) an inadequate
treatment of feedback. Our new results for the total neutral hydrogen mass
density, DLA abundance, and column density distribution function all agree
reasonably well with observational estimates at redshift z=3, indicating that
DLAs arise naturally from radiatively cooled gas in dark matter haloes that
form in a Lambda CDM universe. Our simulations suggest a moderate decrease in
DLA abundance by roughly a factor of two from z=4.5 to 3, consistent with
observations. A significant decline in abundance from z=3 to z=1, followed by
weak evolution from z=1 to z=0, is also indicated, but our low-redshift results
need to be interpreted with caution because they are based on coarser
simulations than the ones employed at high redshift. Our highest resolution
simulation also suggests that the halo mass-scale below which DLAs do not exist
is slightly above 10^8 Msun/h at z=3-4, somewhat lower than previously
estimated. (abridged)


title: Clear Evidence for Intranight Optical Variability in Radio-quiet Quasars

abstract:
  We present new clues to the problem of the radio loudness dichotomy arising
from an extensive search for intranight optical variability in seven sets of
optically luminous radio-quiet quasars and (radio-loud) BL Lacertae objects,
which are matched in optical luminosity and redshift. Our monitoring of
radio-quiet quasars has for the first time clearly detected such intranight
variability, with peak-to-peak amplitudes ~1%, occurring with a duty cycle of ~
1/6. The matched BL Lacs have both higher variability amplitudes and duty
cycles when observed in the same fashion. We show that the much less pronounced
intranight variability of the radio-quiet quasars relative to BL Lacs can be
understood in terms of a modest misalignment of the jets in radio-quiet quasars
from the line-of-sight. We thus infer that relativistic particle jets may well
also emerge from radio-quiet quasars, but while traversing the short
optical-emitting distances, they could be snuffed out, possibly through inverse
Compton losses in the nuclear region.