title: Extent of Excess Far Infrared Emission around Luminosity Class III Stars

abstract:
  With the Infrared Space Observatory, we conducted 3x3-pixel imaging
photometry of twelve luminosity class III stars, which were previously presumed
to have dust particles around them, at far infrared wavelengths (60 and 90 um).
Eleven out of twelve targets show a peak of excess (above photosphere) far
infrared emission at the location of the star, implying that the dust particles
are truly associated with stars. To estimate the size of the excess emission
source, the flux ratio of center to boundary pixels of the 3x3 array was
examined. The radius of the dust emission is found to be ~3000 to ~10000 AU for
a thin shell distribution, and ~5000 to ~25000 AU for a uniform distribution.
We consider three models for the origin of the dust: disintegration of comets,
sporadic dust ejection from the star, and emission from nearby interstellar
cirrus. The data seem to rule out the first model (as far as the "Kuiper--belt"
like particles are assumed to be large blackbody grains), but do not enable us
to choose between the other two models.


title: A study of the gravitational wave form from pulsars

abstract:
  We present analytical and numerical studies of the Fourier transform (FT) of
the gravitational wave (GW) signal from a pulsar,taking into account the
rotation of the Earth for a one day observation period.


title:
Trans-Relativistic Blast Waves in Supernovae as Gamma-Ray Burst
  Progenitors

abstract:
  We investigate the acceleration of shock waves to relativistic velocities in
the outer layers of exploding stars. By concentrating the explosion energy in
the outermost ejecta, such trans-relativistic blast waves can serve as the
progenitors of gamma-ray bursts (GRBs); in particular, the ``baryon-loading''
problem that plagues many models of GRBs is circumvented. We present physically
motivated and numerically validated analytic expressions to describe
trans-relativistic blast waves in supernovae. We find that relativistic ejecta
are enhanced in more centrally condensed envelopes, e.g., for radiative
envelopes, when the luminosity approaches the Eddington limit. We present
convenient formulae for estimating the relativistic ejecta from a given
progenitor. We apply our analytic and numerical methods to a model of SN
1998bw, finding significantly enhanced relativistic ejecta compared to previous
studies. We propose that GRB 980425 is associated with SN 1998bw and may have
resulted from an approximately spherical explosion producing ~10^-6 M_sun of
mildly relativistic ejecta with mean Lorentz factor ~2, which then interacted
with a dense circumstellar wind with mass loss rate ~few x 10^-4 M_sun/yr. A
highly asymmetric explosion is not required. An extreme model of ``hypernova''
explosions in massive stars is able to account for the energetics and
relativistic ejecta velocities required by many of the observed cosmological
GRBs. We present simplified models of explosions resulting from
accretion-induced collapse of white dwarfs and phase transitions of neutron
stars. While we find increased energies in relativistic ejecta compared to
previous studies, these explosions are unlikely to be observed at cosmological
distances with current detectors. (abridged)


title: A Progress Report on the Caltech Faint Galaxy Redshift Survey

abstract:
  I review recent progress on determining the spectral energy distributions and
luminosity functions for galaxies in the large magnitude limited sample in the
region of the HDF-North of the Caltech Faint Galaxy Redshift Survey.


title: The Genesis of Super Star Clusters as Self-Gravitating HII Regions

abstract:
  We examine the effects of ionization, radiation pressure and main sequence
winds from massive stars on self-gravitating, clumpy molecular clouds, thereby
modeling the formation and pre-supernova feedback of massive star clusters. We
find the process of ``turbulent mass loading'' is effective in confining HII
regions. Extrapolating typical Galactic high-mass star forming regions to
greater initial gas cloud masses and assuming steady star formation rates, we
determine the timescales for cloud disruption. We find that a dense n_c ~ 2 x
10^5 cm^-3 cloud with initial mass M_c ~ 4 x 10^5 M_sun is able to form ~2 x
10^5 M_sun of stars (50% efficiency) before feedback disperses the gas after ~3
Myr. This mass and age are typical of young, optically visible super star
clusters (SSCs). The high efficiency permits the creation of a bound stellar
system.


title: Analytical Studies on the Structure and Emission of the SS433 Jets

abstract:
  We study the structure and emission of the SS 433 jets in the X-ray emitting
region and in the inner and hotter portion inside the X-ray emitting region. In
order to consider the jet structure from the inner to outer regions we develop
the hybrid model combining the conical beam and the model beam whose cross
section grows with the distance more slowly. We find that the jet beams in the
inner and hotter portion are of two-temperature and emit a large amount of high
energy gamma photons. Our analyses suggest the thick absorbing envelope to
exist in the SS 433 system. Based on our results, we discuss the possible
acceleration mechanism for the SS 433 jets.


title: Can all breaks in GRB afterglows be explained by jet effects?

abstract:
  Whether gamma-ray bursts are highly beamed or not is a very important
question, since it has been pointed out that the beaming will lead to a sharp
break in the afterglow light curves during the ultra-relativistic phase, with
the breaking point determined by $\Gamma \sim 1/\theta_{0}$, where $\Gamma$ is
the bulk Lorentz factor and $\theta_{0}$ is the initial half opening angle of
the ejecta, and such a break is claimed to be present in the light curves of
some GRBs. In this paper we will examine whether all the observed breaks in GRB
afterglow light curves can be explained by jet effects. Here we present a
detailed calculation of the jet evolution and emission, and have obtained a
simple formula of bulk Lorentz factor evolution. We show that the light curves
are very smoothly steepened by jet effect, and the shape of the light curve is
determined by only one parameter -- $(E/n)^{1/8} \theta_{0}^{3/4}$, where E and
n are the fireball energy and surrounding medium density. We find that for
GRB990123 and GRB991216, the jet model can approximately fit their light
curves, and the values of $(E_{51}/n_1)^{1/8} \theta_{0}^{3/4}$ are about 0.17
and 0.22 respectively. While for GRB990510, GRB000301c, GRB000926 and
GRB010222, their light curves cannot be fitted by the jet model, which suggests
that the breaks may be caused by some other reasons, jet should be not the
unique reason.


title: Morphological Evolution of Galaxies to z=4

abstract:
  Galaxies have clearly evolved since the universe was 1 Gyr old, but methods
to trace and quantify this evolution are still in their infancy. In this paper
I demonstrate that with the careful use of a `physical morphology' it is
possible to determine quantitatively how the process of galaxy evolution is
occurring out to z=4. Using a system of parameters that traces star formation
and galaxy interactions, I show how distinct galaxy populations at high-z can
be identified in deep high-resolution optical and NIR images. These tools are
also used to measure a potential merger fraction of galaxies from 0<z<4. If
these methods are reliable, as is suggested by a local galaxy calibration, the
merger fraction of galaxies scales as (1+z)^{2.1+/-0.5}, peaks near z=2, and
declines thereafter. I also discuss how this system is likely part of the
ultimate physical classification of galaxies.


title: Probing the power spectrum bend with recent CMB data

abstract:
  We constrain the primordial fluctuation spectrum P(k) by using the new data
on the Cosmic Microwave Background (CMB) from the Boomerang and MAXIMA
experiments. Our study is based on slow-roll inflationary models, and we
consider the possibility of a running spectral index. Specifically, we expand
the power spectrum P(k) to second order in ln(k), thus allowing the power
spectrum to ``bend'' in k-space. We show that allowing the power spectrum to
bend erases the ability of the present data to measure the tensor to scalar
perturbation ratio. Moreover, if the primordial baryon density \Omega_b h^2 is
as low as found from Big Bang nucleosynthesis (BBN), the data favor a negative
bending of the power spectrum, corresponding to a bump-like feature in the
power spectrum around a scale of k=0.004 Mpc^-1.


title: Spectroscopic investigation of old planetaries V. Distance scales

abstract:
  We use the results of our recent NLTE model atmosphere analysis of central
stars of old planetary nebulae (PN) to calculate distances. We perform a
comparison with three other methods (trigonometric parallaxes, interstellar NaD
lines, and Shklovsky distances) and discuss the problem of the PNe distance
scale. The result of the comparison of our spectroscopic distances with the
trigonometric distances is that the spectroscopic distances are 55% larger.
Since using trigonometric parallaxes with large relative measurement errors can
introduce systematic errors, we carried out a Monte Carlo simulation of the
biases introduced by selection effects and measurement errors. It turns out
that a difference between both distance scales of the observed size is expected
for the present day data if the underlying distance scales are identical. Thus
our finding is essentially a confirmation of the spectroscopic distance scale!
Good agreement is found between the spectroscopic distances and distances
derived from the interstellar NaD lines.
  All three independent methods of distance measurement indicate that the
widely used "statistical" distance scales of the Shklovsky type are too short
for old PNe. A correlation with nebular radii exists. The most likely
explanation is an underestimate of the nebula masses for large PN. Implications
for the nebula masses are discussed. Estimates of the PNe space density and
birthrate, which are based on Shklovsky type distances, therefore give too
large values.


title:
The obscured mid-infrared continuum of NGC 4418: a dust- and
  ice-enshrouded AGN

abstract:
  We report the detection of absorption features in the 6-8 micron region
superimposed on a featureless mid-infrared continuum in NGC 4418. For several
of these features this is the first detection in an external galaxy. We compare
the absorption spectrum of NGC 4418 to that of embedded massive protostars and
the Galactic centre, and attribute the absorption features to ice grains and to
hydrogenated amorphous carbon grains. From the depth of the ice features, the
powerful central source responsible for the mid-infrared emission must be
deeply enshrouded. Since this emission is warm and originates in a compact
region, an AGN must be hiding in the nucleus of NGC 4418.


title: Cosmological models: theory and observations

abstract:
  The current status of the theoretical and observational cosmology is
reviewed.


title: Two-dimensional disk dynamos with vertical outflows into a halo

abstract:
  We study the effects of vertical outflows on mean-field dynamos in disks.
These outflows could be due to thermal winds or magnetic buoyancy. We analyse
numerical solutions of the nonlinear mean-field dynamo equations using a
two-dimensional finite-difference model. Contrary to expectations, a modest
vertical velocity can enhance dynamo action. This can lead to super-exponential
growth of the magnetic field and to higher magnetic energies at saturation in
the nonlinear regime.


title: $\Lambda$-Inflation and CMBR Anisotropy

abstract:
  We argue that a $\Lambda$-inflation model can ensure large relative
contribution of cosmic gravity waves into the $\Delta T/T$ at COBE scale
preserving at the same time a near scale-invariant spectrum of cosmological
density perturbations favored by observational data ($n_S\simeq 1$). High
efficiency of these models to meet observational tests is discussed.


title:
Cepheid Calibration of the Peak Brightness of SNe Ia. X. SN 1991T in NGC
  4527

abstract:
  Repeated imaging observations have been made of NGC 4527 with the Hubble
Space Telescope between April and June 1999, over an interval of 69 days.
Images were obtained on 12 epochs in the F555W band and on five epochs in the
F814W band. The galaxy hosted the type Ia supernova SN1991T, which showed
relatively unusual behavior by having both an abnormal spectrum near light
maximum, and a slower declining light curve than the proto-typical Branch
normal SNe Ia.
  A total of 86 variables that are putative Cepheids have been found, with
periods ranging from 7.4 days to over 70 days. From photometry with the DoPHOT
program, the de-reddened distance modulus is determined to be (m-M)_0 = 30.67
+/- 0.12 (internal uncertainty) using a subset of the Cepheid data whose
reddening and error parameters are secure. A parallel analysis of the Cepheids
using photometry with ROMAFOT yields (m -M)_0 =30.82 +/- 0.11. The final
adopted modulus is (m -M)_0 =30.74 +/- 0.12 +/- 0.12 (d=14.1 +/- 0.8 +/- 0.8
Mpc).
  The photometric data for SN1991T are used in combination with the Cepheid
distance to NGC 4527 to obtain the absolute magnitude for this supernova of
M_V^0(max) = -19.85 +/- 0.29. The relatively large uncertainty is a result of
the range in estimates of the reddening to the supernova. Thus SN1991T is seen
to be only moderately brighter (by ~ 0.3 mag) than the mean for
spectroscopically normal supernovae, although magnitude differences of up to
0.6 mag cannot be ruled out.


title: Sunyaev-Zel'dovich distortion from early galactic winds

abstract:
  We consider the distortion in the cosmic microwave background (CMB) due to
galactic winds at high redshift. Winds outflowing from galaxies have been
hypothesized to be possible sources of metals in the intergalactic medium,
which is known to have been enriched to $10^{-2.5}$ Z$_{\odot}$ at $z \sim 3$.
We model these winds as functions of mass of the parent galaxy and redshift,
assuming they activate at a common initial redshift, $z_{in}$, and calculate
the mean $y$ distortion and the angular power spectrum of the distortion in the
CMB. We find that the thermal Sunyaev-Zel'dovich (SZ) effect due to the winds
to be consistent with previous estimates. The distortion due to the kinetic SZ
(kSZ) effect is, however, found to be more important than the thermal SZ (tSZ)
effect. We find that the distortion due to galactic winds is an important
contribution to the power spectrum of distortion at very small angular scales
$(l \sim 10^4)$. We also find that the power spectrum due to clustering
dominates the Poisson power spectrum for $l \le 4\hbox{--}5 \times 10^5$. We
show explicitly how the combined power spectrum from wind dominates over that
of clusters at 217 GHz, relevant for PLANCK. We also show how these constraints
change when the efficiency of the winds is varied.


title: Inner Disk Oscillations and QPOs in Relativistic Jet Sources

abstract:
  Recent results on the inner disk oscillations found in GRS 1915+105 are
reviewed. QPOs during the low state are used as a marker for such oscillations
and the physical picture emerging from a combined X-ray spectral and timing
analysis is examined. The relationship between inner disk oscillations and
synchrotron radio emission is critically evaluated.


title: Current Status of cosmological models with mixed dark matter

abstract:
  An analysis of cosmological mixed dark matter models in spatially flat
Friedmann Universe with zero $\Lambda$-term is presented. We argue that the
introduction of cosmic gravity waves helps to satisfy observational
constraints. The analysis of models is based on the confrontation with the mass
function of clusters of galaxies and the CMB anisotropy. The implication of
Press-Schechter formalism allowed to constrain $\sigma_8=0.52 \pm 0.01$. This
normalisation of the spectrum of density perturbations has been used to
calculate numerically the value of the large scale CMB anisotropy and the
relative contribution of cosmological gravitational waves, T/S. We found that
increasing $\Omega_\nu$ weakens the requirements to the value of T/S, however
even for $\Omega_\nu\le 0.4$ the models with $h+n\ge 1.5$ suggest considerable
abundance of gravitational waves, T/S${}^>_\sim 0.3$. Minimisation of the value
T/S is possible only in the range of the red spectra ($n<1$) and small $h$
($<0.6$). However the parameter $\Omega_\nu$ is strongly constrained by $\Delta
T/T$ data on the first acoustic peak of Sakharov oscillations. Assuming that
T/S $\in[0,3]$ and taking into account observational data on the amplitude of
the first acoustic peak we constrain the model parameters. We show that the
considered models admit both moderate red and blue spectra of density
perturbations $n\in [0.9,1.2]$ with rather high abundance hot dark matter,
$\Omega_\nu \in [0.2,0.4]$. Any condition, $n<0.9$ or $\Omega_\nu<0.2$,
decreases the relative amplitude of the first acoustic peak for more than 30%
in comparison with its height measured by BOOMERanG.


title: Singular Isothermal Disks and the Formation of Multiple Stars

abstract:
  A crucial missing ingredient in previous theoretical studies of fragmentation
is the inclusion of dynamically important levels of magnetic fields. As a
minimal model for a candidate presursor to the formation of binary and multiple
stars, we therefore consider the equilibrium configuration of isopedically
magnetized, scale-free, singular isothermal disks, without the assumption of
axial symmetry. We find that lopsided (M=1) configurations exist at any
dimensionless rotation rate, including zero. Multiple-lobed (M = 2, 3, 4, ...)
configurations bifurcate from an underlying axisymmetric sequence at
progressively higher dimensionless rates of rotation, but such nonaxisymmetric
sequences always terminate in shockwaves before they have a chance to fission
into separate bodies. We advance the hypothesis that binary and multiple
star-formation from smooth (i.e., not highly turbulent) starting states that
are supercritical but in unstable mechanical balance requires the rapid (i.e.,
dynamical) loss of magnetic flux at some stage of the ensuing gravitational
collapse.


title: Planetary dynamics in stellar clusters

abstract:
  We investigate how the formation and evolution of extrasolar planetary
systems can be affected by stellar encounters that occur in the crowded
conditions of a stellar cluster. Using plausible estimates of cluster
evolution, we show how planet formation may be supressed in globular clusters
while planets wider than 0.1 AU that do form in such environments can be
ejected from their stellar system. Less crowded systems such as open clusters
have a much reduced effect on any planetary system. Planet formation is
unaffected in open clusters and only the wider planetary systems will be
disrupted during the cluster's lifetime. The potential for free-floating
planets in these environments is also discussed.


title: Why is the Hubble flow so quiet?

abstract:
  The cosmological vacuum, which is perfectly uniform, dominates by density
over all the forms of cosmic matter. It makes the Universe be actually more
uniform than it could be seen from the visible picture of the highly
non-uniform matter distribution, especially inside the observed cell of
uniformity (100-150 Mpc). This uniformity reveals itself in the structure of
the Hubble matter flow which extends over a giant range of cosmic space scales
-- from few Mpc to a thousand Mpc, -- preserving its kinematical identity.
According to Sandage (1999), this flow is mysteriously regular and quiet even
deep inside the cell of uniformity. An answer we propose to the question in the
title above is as follows: This is most probably because the flow is
dynamically controlled by the cosmological vacuum. An additional conjecture of
cosmological intermittency, that addresses a complex statistical structure of
initial chaotic perturbations, is also suggested in this context.


title: The star-formation history of the universe - an infrared perspective

abstract:
  A simple and versatile parameterized approach to the star formation history
allows a quantitative investigation of the constraints from far infrared and
submillimetre counts and background intensity measurements.
  The models include four spectral components: infrared cirrus (emission from
interstellar dust), an M82-like starburst, an Arp220-like starburst and an AGN
dust torus. The 60 $\mu$m luminosity function is determined for each chosen
rate of evolution using the PSCz redshift data for 15000 galaxies. The
proportions of each spectral type as a function of 60 $\mu$m luminosity are
chosen for consistency with IRAS and SCUBA colour-luminosity relations, and
with the fraction of AGN as a function of luminosity found in 12 $\mu$m
samples. The luminosity function for each component at any wavelength can then
be calculated from the assumed spectral energy distributions. With assumptions
about the optical seds corresponding to each component and, for the AGN
component, the optical and near infrared counts can be accurately modelled.
  A good fit to the observed counts at 0.44, 2.2, 15, 60, 90, 175 and 850
$\mu$m can be found with pure luminosity evolution in all 3 cosmological models
investigated: $\Omega_o$ = 1, $\Omega_o$ = 0.3 ($\Lambda$ = 0), and $\Omega_o$
= 0.3, $\Lambda$ = 0.7.
  All 3 models also give an acceptable fit to the integrated background
spectrum. Selected predictions of the models, for example redshift
distributions for each component at selected wavelengths and fluxes, are shown.
  The total mass-density of stars generated is consistent with that observed,
in all 3 cosmological models.


title: Galaxy Formation: Was There A Big Bang Shell?

abstract:
  The tight correlation of galactic velocity distribution to both luminosity
and its black hole mass and the relation of halo parameters to luminous mass
distribution, can not be due to collapse dynamics. A big bang shell can solve
galaxy formation problems by forming the supermassive black holes necessary to
capture the initial blast wave in a coordinated pattern.


title: Models for infrared and submillimetre counts and backgrounds

abstract:
  A simple and versatile parameterized approach to the star formation history
allows a quantitative investigation of the constraints from far infrared and
submillimetre counts and background intensity measurements.
  The models include four spectral components: infrared cirrus, an M82-like
starburst, an Arp220-like starburst and an AGN dust torus. The 60 $\mu$m
luminosity function is determined for each chosen rate of evolution using the
PSCz redshift data for 15000 galaxies. The proportions of each spectral type as
a function of 60 $\mu$m luminosity are chosen for consistency with IRAS and
SCUBA colour-luminosity relations, and with the fraction of AGN as a function
of luminosity found in 12 $\mu$m samples.
  A good fit to the observed counts at 0.44, 2.2, 15, 60, 90, 175 and 850
$\mu$m can be found with pure luminosity evolution in all 3 cosmological models
investigated: $\Omega_o$ = 1, $\Omega_o$ = 0.3 ($\Lambda$ = 0), and $\Omega_o$
= 0.3, $\Lambda$ = 0.7. All 3 models also give an acceptable fit to the
integrated background spectrum. The total mass-density of stars generated is
consistent with that observed, in all 3 cosmological models.


title:
Models for the IR and submm SEDs of normal, starburst and active
  galaxies

abstract:
  Models for the seds of infrared galaxies are reviewed, with particular
application to hyperluminous infrared galaxies.


title: Cosmological Parameters: do we already know the final answer ?

abstract:
  Some of the arguments which support the strong concensus for an $\Omega_o$ =
0.3, $\lambda_o$ = 0.7 model are reexamined. Corrections for Malmquist bias,
local flow and metallicity suggest a revised value for $H_o$ of 63 $\pm$ 6
km/s/Mpc, improving the age problems for an $\Omega_o$ = 1 universe. The latest
CMB results may require a high baryon density and hence new physics, for
example a strong lepton asymmetry. Difficulties for the $\Omega_o$ = 1 model
with cluster evolution, the baryon content of clusters, and the evidence from
Type Ia supernovae favouring low $\Omega_o$, $\Lambda > 0$ models, are
discussed critically.


title:
Predicting the peculiar velocities of nearby PSC-z galaxies using the
  Least Action Principle

abstract:
  We use the Least Action Principle to predict the peculiar velocities of PSC-z
galaxies inside $cz=2000$\km. Linear theory is used to account for tidal
effects to $cz=15000$\km, and we iterate galaxy positions to account for
redshift distortions. As the Least Action Principle is valid beyond Linear
theory, we can predict reliable peculiar velocities even for very nearby
galaxies (ie $cz \leq 500$\km). These predicted peculiar velocities are then
compared with the observed velocities of 12 galaxies with Cepheid distances.
The combination of the PSC-z galaxy survey (with its large sky coverage and
uniform selection), with the accurate Cepheid distances, makes this comparison
relatively free from systematic effects. We find that galaxies are good tracers
of the mass, even at small ($\leq 10$\mpc) scales; and under the assumption of
no biasing, $0.25 \leq \beta \leq 0.75$ (at 90% confidence). We use the
reliable predicted peculiar velocities to estimate the Hubble constant \ho from
the local volume without ``stepping up'' the distance ladder, finding a
confidence range of 65-75\kmM (at 90% confidence).


title:
Gas kinematics from spectroscopy with a wide slit: detecting nuclear
  black holes

abstract:
  Motivated by STIS observations of more than 50 nearby galactic nuclei, we
consider long-slit emission-line spectra when the slit is wider than the
instrumental PSF, and the target has arbitrarily large velocity gradients. The
finite width of the slit generates complex patterns in the spectra that can be
misinterpreted as coming from various physically distinct nuclear components,
but when interpreted correctly, they can have considerable diagnostic power.
For a thin disk in circular motion around a central galactic black hole (BH), a
characteristic artifact occurs in the spectrum at the outer edge of the BH's
sphere of influence. It betrays the presence of a BH, and allows us to develop
a new method for estimating its mass, which gives higher sensitivity to BH
detection than traditional methods.


title: Steady-state structure of relativistic collisionless shocks

abstract:
  We explore analytically the structure of relativistic shock and solitary wave
solutions in collisionless plasmas. In the wave frame of reference, a cold
plasma is flowing from one end and impacting on a low velocity plasma. First we
show that under astrophysical conditions, a cold electron-positron plasma is
unstable with respect to a two-stream instability in the interface between
these regions. The instability heats the inflowing cold plasma rapidly, on a
timescale comparable to the inverse of its plasma frequency. We then derive
time-independent equations to describe the resulting hot state of the pair
plasma, and describe the conditions under which the spatially uniform solution
is the unique stable solution for the post shock conditions. We also examine
plasmas composed of cold protons and hot electrons, and show that the spatially
uniform solution is the unique stable solution there as well. We state the
shock jump conditions which connect a cold, electron-proton plasma to a hot
electron-proton plasma. The generic feature evident in all of these models is
that the plasma's initial, directed kinetic energy gets almost completely
converted into heat. The magnetic field plays the role of catalyst which can
induce the plasma instability, but our solutions indicate that the macroscopic
field only gets amplified by a factor of approximately three in the frame of
the shock.


title: Broad P Cygni X-ray Lines from Circinus X-1

abstract:
  Chandra High Energy Transmission Grating Spectrometer (HETGS) observations of
the extremely luminous and violent X-ray binary Cir X-1 reveal many X-ray
emission lines showing broad P Cygni profiles. These are from H-like and
He-like ions of Ne, Mg, Si, S, Ar, and Fe. The lines originate in a
high-velocity (up to 2000 km s^-1) outflow, which may be an accretion disk
wind. Cir X-1 has a radio jet, and during some periastron passages of the
neutron star (orbital phase = 0.0), it flares at radio, infrared and X-ray
wavelengths. The X-ray P Cygni profiles were observed during this phase, where
we also expect the strongest mass transfer from the companion star. We present
new results on the time variability of the P Cygni profiles and discuss their
general importance.


title: A Cosmological Window on Trans-Planckian Physics

abstract:
  In the framework of inflation, scales which nowadays correspond to large
scale structures were smaller than the Planck length at the beginning of
inflation. Therefore, measurements of CMBR anisotropy or surveys of galaxies
and of clusters of galaxies could help us to probe physics beyond the Planck
scale. In these proceedings, we study how the inflationary observables depend
on trans-Planckian physics. It is found that there exist cases where
adiabaticity can be violated and the primordial spectrum of the quantum
cosmological perturbations modified. These cases correspond to rather drastic
alterations of the dispersion relation. There exist also modifications of the
standard physics which leave the power spectrum unchanged and therefore which
are compatible with the data. In this sense, the presently available
observations already constrain trans-Planckian physics.


title: Accretion and Outflow Traced by Water Masers in the Circinus AGN

abstract:
  The first VLBI images of water maser emission in the Circinus Galaxy AGN show
both a warped, edge-on accretion disk and an outflow 0.1 to 1 pc from the
central engine. The inferred central mass is 1.3 million suns, while the disk
mass may be on the order of 0.1 million suns, based on a nearly Keplerian
rotation curve. The bipolar, wide-angle outflow appears to contain ``bullets''
ejected from within <0.1 pc of the central mass. The positions of filaments and
bullets observed in the AGN ionization cone on kpc-scales suggest that the disk
channels the flow to a radius of about 0.4 pc, at which the flow appears to
disrupt the disk.


title: Physical Modelling of the Zodiacal Dust Cloud

abstract:
  (abridged) This review is based on an extensive work done in collaboration
with N. Gorkavyi, J. Mather, and T. Taidakova, which aimed at the physical
modelling of the interplanetary dust (IPD) cloud in the Solar system, i.e.,
establishing a link between the observable characteristics of the zodiacal
cloud and the dynamical and physical properties of the parent minor bodies. Our
computational approach permits with modest computer resources to integrate the
trajectories of hundreds of particles and to effectively store up to
$10^{10-11}$ positions, which provides a high fidelity 3D distribution of the
dust. Our numerical codes account for the major dynamical effects that govern
the motion of IPD particles. We have demonstrated the efficacy of our codes by
performing the following analyses: (i) simulation of the distribution of
Centaurs (comets scattered in their journey from the Kuiper belt inward the
Solar system) and revealing the effects of the outer planets in producing
`cometary belts'; (ii) detailed inspection of a rich resonant structure found
in these belts, which predicts the existence of gaps similar to the Kirkwood
gaps in the main asteroid belt; (iii) a preliminary 3-D physical model of the
IPD cloud, which includes three dust components -- asteroidal, cometary, and
kuiperoidal -- and is consistent with the available data of Pioneers and
Voyagers dust detectors; (iv) modeling of the IPD cloud, which provides a
zodiacal light distribution in accord, to the order of 1%, with a subset of the
COBE/DIRBE observations; and (v) showing that the resonant structure in dusty
circumstellar disks of Vega and Epsilon Eridani is a signature of embedded
extrasolar planets. Further improvements of our modelling and their importance
for astronomy and cosmology are outlined.


title:
Reddenings and metallicities in the LMC and SMC from Stroemgren CCD
  photometry

abstract:
  The individual reddenings for B stars in two fields in the Small Magellanic
Cloud (SMC) and two fields in the Large Magellanic Cloud (LMC) are determined
by means of Stroemgren uvby CCD photometry. In both LMC fields we find a
foreground reddening of E(B-V) = 0.085 +/- 0.02, and for the SMC fields we find
E(B-V) = 0.070 +/- 0.02. In addition to the foreground reddening we find
contributions from reddening intrinsically in the Clouds up to E(B-V) ~ 0.21.
The intrinsic contribution is not correlated with position within our 6 x 4.5
arcmin CCD fields but varies in an essentially random way. Unless the reddening
is measured for a particular object, it will be uncertain by +/- 0.035 in
E(B-V) (best case, far from the central bars) to more than +/- 0.10 (close to
the central bars).
  The Stroemgren vby photometry has been used to derive metallicities for GK
giant stars in the observed fields. Adopting average reddenings we obtain mean
metallicities which are consistent with those found from spectroscopic studies
of F and G supergiants but with a considerable scatter, from [Fe/H]~ -2.0 to >
0. A significant fraction of the scatter is, however, due to reddening
variations rather than being intrinsic. The possible existence of high
metallicity stars should be investigated further using spectroscopic methods.


title: The Seyfert-Starburst Connection in X-rays. I. The Data

abstract:
  We analyze X-ray spectra and images of a sample of Seyfert 2 galaxies that
unambiguously contain starbursts, based on their optical and UV
characteristics. Although all sample members contain active galactic nuclei
(AGNs), supermassive black holes or other related processes at the galactic
centers alone cannot account for the total X-ray emission in all instances.
Eleven of the twelve observed galaxies are significantly resolved with the
ROSAT HRI, while six of the eight sources observed with the lower-resolution
PSPC also appear extended on larger scales. The X-ray emission is extended on
physical scales of 10 kpc and greater, which we attribute to starburst-driven
outflows and supernova-heating of the interstellar medium. Spectrally, a
physically-motivated composite model of the X-ray emission that includes a
heavily absorbed (N_H > 10^{23} cm^{-2}) nuclear component (the AGN), power-law
like scattered AGN flux, and a thermal starburst describes this sample well.
Half the sample exhibit iron K alpha lines, which are typical of AGNs.


title: The Seyfert-Starburst Connection in X-rays. II. Results and Implications

abstract:
  We present the results of X-ray imaging and spectroscopic analysis of a
sample of Seyfert 2 galaxies that contain starbursts, based on their optical
and UV characteristics. These composite galaxies exhibit extended, soft,
thermal X-ray emission, which we attribute to their starburst components.
Comparing their X-ray and far-infrared properties with ordinary Seyfert and
starburst galaxies, we identify the spectral characteristics of their various
intrinsic emission sources. The observed far-infrared emission of the composite
galaxies may be associated almost exclusively with star formation, rather than
the active nucleus. The ratio of the hard X-ray luminosity to the far-infrared
and [O III] 5007 luminosity distinguishes most of these composite galaxies from
``pure'' Seyfert 2 galaxies, while their total observed hard X-ray luminosity
distinguishes them from ``pure'' starbursts. The hard nuclear X-ray source is
generally heavily absorbed (N_H > 10^{23} cm^{-2}) in the composite galaxies.
Based on these results, we suggest that the interstellar medium of the nuclear
starburst is a significant source of absorption. The majority of the sample are
located in groups or are interacting with other galaxies, which may trigger the
starburst or allow rapid mass infall to the central black hole, or both. We
conclude that starbursts are energetically important in a significant fraction
of active galaxies, and starbursts and active galactic nuclei may be part of a
common evolutionary sequence.


title: Evidence Against a Redshift z>6 for the Galaxy STIS 123627+621755

abstract:
  The identification of galaxies at extreme distances provides our most direct
information on the earliest phases of galaxy formation. The distance implied by
redshifts z > 5 makes this a challenging endeavor for even the most luminous
sources; interpretation of low signal-to-noise ratio observations of faint
galaxies is difficult and occasional misidentifications will occur. Here we
report on STIS 123627+621755, a galaxy with a suggested spectroscopic redshift
of z = 6.68 and the most distant spectroscopically-identified object claimed.
For the suggested redshift and reported spectral energy distribution, the
galaxy should be essentially invisible shortward of 9300 Angstroms because the
intervening intergalactic medium absorbs essentially all light energetic enough
to ionize neutral hydrogen (lambda < (1 + z) x 912 Angstroms; the redshifted
Lyman limit). The galaxy should be relatively bright in the near-infrared with
f(nu) ~ 1 microJy. Here we report a detection of the galaxy at 6700 Angstroms,
below the Lyman limit for z = 6.68. We also report a non-detection at 1.2
microns, implying the flux has dropped by a factor of three or more between
rest 1216 Angstroms and rest 1560 Angstroms for z = 6.68. Our observations are
inconsistent with the suggested extreme distance of STIS 123627+621755 and
conservatively require z < 6.


title: The Coalescence Rate of Double Neutron Star Systems

abstract:
  We estimate the coalescence rate of close binaries with two neutron stars
(NS) and discuss the prospects for the detection of NS-NS inspiral events by
ground-based gravitational-wave observatories, such as LIGO. We derive the
Galactic coalescence rate using the observed sample of close NS-NS binaries
(PSR B1913+16 and PSR B1534+12) and examine in detail each of the sources of
uncertainty associated with the estimate. Specifically, we investigate (i) the
dynamical evolution of NS-NS binaries in the Galactic potential and the
vertical scale height of the population, (ii) the pulsar lifetimes, (iii) the
effects of the faint end of the radio pulsar luminosity function and their
dependence on the small number of observed objects, (iv) the beaming fraction,
and (v) the extrapolation of the Galactic rate to extragalactic distances
expected to be reachable by LIGO. We find that the dominant source of
uncertainty is the correction factor (up to about 200) for faint (undetectable)
pulsars. All other sources are much less important, each with uncertainty
factors smaller than 2. Despite the relatively large uncertainty, the derived
coalescence rate is approximately consistent with previously derived upper
limits, and is more accurate than rates obtained from population studies. We
obtain a most conservative lower limit for the LIGO II detection rate of 2
events per year. Our upper limit on the detection rate lies between 300 to more
than 1000 events per year.


title: The bulge luminosity functions in the MSX infrared bands

abstract:
  We use an inversion technique to derive the luminosity functions of the
Galactic bulge from point source counts extracted from the Midcourse Space
Experiment's Point Source Catalog (version 1.2).


title:
Possible galactic sources of ultrahigh-energy cosmic rays and a strategy
  for their detection via gravitational lensing

abstract:
  If decays of superheavy relic particles in the galactic halo are responsible
for ultrahigh-energy cosmic rays, these particles must be clustered to account
for small-scale anisotropy in the AGASA data. We show that the masses of such
clusters are large enough for them to gravitationally lens stars and galaxies
in the background. We propose a general strategy that can be used to detect
such clusters via gravitational lensing, or to rule out the hypothesis of
decaying relic particles as the origin of highest-energy cosmic rays.


title:
Pseudoparticle Multipole Method: A Simple Method to Implement
  High-Accuracy Treecode

abstract:
  In this letter we describe the pseudoparticle multipole method (P2M2), a new
method to express multipole expansion by a distribution of pseudoparticles. We
can use this distribution of particles to calculate high order terms in both
the Barnes-Hut treecode and FMM. The primary advantage of P2M2 is that it works
on GRAPE. GRAPE is a special-purpose hardware for the calculation of
gravitational force between particles. Although the treecode has been
implemented on GRAPE, we could handle terms only up to dipole, since GRAPE can
calculate forces from point-mass particles only. Thus the calculation cost
grows quickly when high accuracy is required. With P2M2, the multipole
expansion is expressed by particles, and thus GRAPE can calculate high order
terms. Using P2M2, we implemented an arbitrary-order treecode on GRAPE-4.
Timing result shows GRAPE-4 accelerates the calculation by a factor between 10
(for low accuracy) to 150 (for high accuracy). Even on general-purpose
programmable computers, our method offers the advantage that the mathematical
formulae and therefore the actual program is much simpler than that of the
direct implementation of multipole expansion.


title:
Implications of the PSR 1257+12 Planetary System for Isolated
  Millisecond Pulsars

abstract:
  The first extrasolar planets were discovered in 1992 around the millisecond
pulsar PSR 1257+12. We show that recent developments in the study of accretion
onto magnetized stars, plus the existence of the innermost, moon-sized planet
in the PSR 1257+12 system, suggest that the pulsar was born with approximately
its current rotation frequency and magnetic moment. If so, this has important
implications for the formation and evolution of neutron star magnetic fields as
well as for the formation of planets around pulsars. In particular, it suggests
that some and perhaps all isolated millisecond pulsars may have been born with
high spin rates and low magnetic fields instead of having been recycled by
accretion.


title: Small-scale structure deduced from X- and gamma-ray timing measurements

abstract:
  X-ray timing observations of neutron stars and black holes are among the few
available probes of ultrastrong magnetic fields, strong gravity, high
densities, and the propagation of thermonuclear burning. Here we review the
evidence for these effects revealed with data from the Rossi Explorer in the
last five years. We also discuss the exciting prospects for making the first
quantitative tests of strong-gravity general relativistic predictions with a
large-area X-ray timing mission.


title: The Optical-Near-IR Spectrum of the M87 Jet From HST Observations

abstract:
  We present 1998 HST observations of M87 which yield the first single-epoch
optical and radio-optical spectral index images of the jet at $0.15''$
resolution. We find $<\alpha_{ro} > \approx 0.67$, comparable to previous
measurements, and $<\alpha_o > \approx 0.9$ ($F_\nu \propto \nu^{-\alpha}$),
slightly flatter than previous workers. Reasons for this discrepancy are
discussed. These observations reveal a large variety of spectral slopes. Bright
knots exhibit flatter spectra than interknot regions. The flattest spectra
($\alpha_o \sim 0.5-0.6$; comparable to or flatter than $\alpha_{ro}$) are
found in two inner jet knots (D-East and HST-1) which contain the fastest
superluminal components. In knots A, B and C, $\alpha_o$ and $\alpha_{ro}$ are
essentially anti-correlated. Near the flux maxima of knots HST-1 and F, changes
in $\alpha_{ro}$ lag changes in $\alpha_o$, but in knots D and E, the opposite
relationship is observed. This is further evidence that radio and optical
emissions in the M87 jet come from substantially different physical regions.
The delays observed in the inner jet are consistent with localized particle
acceleration, with $t_{acc} << t_{cool}$ for optically emitting electrons in
knots HST-1 and F, and $t_{acc} \sim t_{cool}$ for optically emitting electrons
in knots D and E. Synchrotron models yield $\nu_B \gsim 10^{16}$ Hz for knots
D, A and B, and somewhat lower values, $\nu_B \sim 10^{15}- 10^{16}$ Hz, in
other regions. If X-ray emissions from knots A, B and D are co-spatial with
optical and radio emission, we can strongly rule out the ``continuous
injection'' model. Because of the short lifetimes of X-ray synchrotron emitting
particles, the X-ray emission likely fills volumes much smaller than the
optical emission regions.


title:
Precise Masses for Wolf 1062 AB from Hubble Space Telescope
  Interferometric Astrometry and McDonald Observatory Radial Velocities

abstract:
  We present an analysis of astrometric data from FGS 3, a white-light
interferometer on {\it HST}, and of radial velocity data from two ground-based
campaigns. We model the astrometric and radial velocity measurements
simultaneously to obtain parallax, proper motion and component masses for Wolf
1062 = Gl 748 AB (M3.5V). To derive the mass fraction, we relate FGS 3 fringe
scanning observations of the science target to a reference frame provided by
fringe tracking observations of a surrounding star field. We obtain an absolute
parallax $\pi_{abs} = 98.0 \pm 0.4$ milliseconds of arc, yielding ${\cal M}_A =
0.379 \pm 0.005{\cal M}_{\sun}$ and ${\cal M}_B= 0.192 \pm 0.003 {\cal
M}_{\sun}$, high quality component masses with errors of only 1.5%.


title: Nucleosynthesis Calculations for the Ejecta of Neutron Star Coalescences

abstract:
  We present the results of fully dynamical r-process network calculations for
the ejecta of neutron star mergers (NSMs). The late stages of the inspiral and
the final violent coalescence of a neutron star binary have been calculated in
detail using a 3D hydrodynamics code (Newtonian gravity plus backreaction
forces emerging from the emission of gravitational waves) and a realistic
nuclear equation of state. The found trajectories for the ejecta serve as input
for dynamical r-process calculations where all relevant nuclear reactions
(including beta-decays depositing nuclear energy in the expanding material) are
followed. We find that all the ejected material undergoes r-process. For an
initial Ye close to 0.1 the abundance distributions reproduce very accurately
the solar r-process pattern for nuclei with A above 130. For lighter nuclei
strongly underabundant (as compared to solar) distributions are encountered. We
show that this behaviour is consistent with the latest observations of very
old, metal-poor stars, despite simplistic arguments that have recently been
raised against the possibility of NSM as possible sources of Galactic r-process
material.


title:
Astrophysical tests for the Novello-De Lorenci-Luciane theory of
  gravity: Gravitational-wave + neutrino bursts from local supernovae and
  gravitational-wave microlensing by Galactic (MACHOs) black holes

abstract:
  The Novello-DeLorenci-Luciane (NDL) field theory of gravitation predicts that
gravitational waves (GWs) follow geodesics of a modified (effective) geometry
with a speed lower than the velocity of light. The theory also demonstrates
that GWs exhibit the phenomenon of birefringence, formerly believed to be
exclusive of electromagnetic waves. Here prospective astrophysical tests of
these predictions are proposed. I point out that future measurements of
gravitational waves in coincidence with a non-gravitational process such as
{\it a neutrino burst} (and likely a burst of gamma-rays) may prove useful to
discriminate among all the existing theories of gravity. It is also stressed
that microlensing of gravitational waves emitted by known galactic sources
(i.e., pulsars) in the bulge, lensed by either the Galaxy's central black hole
(Sgr A$^\ast$) or a MACHO object adrift among the Milky Way's stars, may
provide a clean test of the birefringence phenomenon implied by the NDL gravity
theory.


title:
How astrophysical mean field dynamos can circumvent existing quenching
  constraints

abstract:
  Mean field dynamo theory is a leading candidate to explain the observed large
scale magnetic fields of galaxies and stars. However, controversy arises over
the extent of premature quenching by the backreaction of the growing field. We
distinguish between rapid mean field dynamo action, which is required by
astrophysical systems, and resistively limited action. We show how the flow of
magnetic helicity is important for rapid action. Existing numerical and
analytic work suggesting that mean field dynamos are prematurely quenched and
resistively limited include approximations or boundary conditions which
suppress the magnetic helicity flow from the outset. Thus they do not
unambiguously reveal whether real astrophysical mean field dynamos are
dynamically suppressed when the helicity flow is allowed. An outflow of
helicity also implies an outflow of magnetic energy and so active coronae or
winds should accompany mean field dynamos. Open boundaries alone may not be
sufficient for rapid dynamo action and the additional physics of buoyancy and
outflows may be required. Possible simulation approaches to test some of the
principles are briefly discussed. Some limitations of the ``Zeldovich
relation'' are also addressed.


title: Neutron Star Kicks and Asymmetric Supernovae

abstract:
  Observational advances over the last decade have left little doubt that
neutron stars received a large kick velocity (of order a few hundred to a
thousand km/s) at birth. The physical origin of the kicks and the related
supernova asymmetry is one of the central unsolved mysteries of supernova
research. We review the physics of different kick mechanisms, including
hydrodynamically driven, neutrino -- magnetic field driven, and
electromagnetically driven kicks. The viabilities of the different kick
mechanisms are directly related to the other key parameters characterizing
nascent neutron stars, such as the initial magnetic field and the initial spin.
Recent observational constraints on kick mechanisms are also discussed.


title: Does Light Gravitate? (Proposal on New Test of Equivalence Principle)

abstract:
  On the basis of the relativistic mass-energy concept we found that a proper
mass of a test particle in a gravitational field depends on a potential energy,
hence, a freely falling particle has a varying proper mass. Consequently, a
multitude of freely falling reference frames cannot be regarded as the
multitude of equivalent inertial reference frames. There is a class of
experiments, which allow distinguishing between them. If so, a demonstration of
a violation of the Equivalence Principle is possible. It is shown that a
variant of the classical Pound-Rebka-Snider experiment on a photon frequency
shift in a gravitational field if conducted in a freely falling laboratory
would be such a test.


title: Why Are There Dwarf Spheroidal Galaxies?

abstract:
  There appears to exist a conflict between the standard structure formation
theory and the existence of the faint dwarf spheroidal galaxies in the Local
Group. Theoretical considerations suggest that a cold dark matter universe has
been a very hostile place for the formation of small galaxies. In particular,
gas would not have been able to cool and condense to form stars inside dark
matter halos with a velocity dispersion <10km/s since before the cosmological
reionization epoch. In other words, one should not expect to see any major star
formation activities in dwarf galaxies with a velocity dispersion <10km/s
during the past 12Gyr, according to the current structure formation theory. The
real universe, on the other hand, shows that all dwarf spheroidal galaxies in
the Local Group have velocity dispersions <10km/s and extended and recent star
formation activities are quite common in them. This apparent conflict between
cold dark matter models and local observations can be resolved, if one allows
the cold dark matter particles to decay relatively recently. The resolution
comes about in that the dwarf spheroidal galaxies with a velocity dispersion of
\~10km/s seen today were born, in this picture, in a small fraction of halos
with a velocity dispersion of ~20km/s, where gas can be retained and is able to
cool and contract to form stars. The presently observed lower velocity
dispersion ~10km/s of these dwarf spheroidal galaxies is a consequence of the
decay of one half of the dark matter in and subsequent expansion of the halos
since redshift z~2.


title:
Sunyaev-Zel'dovich Effect Imaging of Massive Clusters of Galaxies at
  Redshift z > 0.8

abstract:
  We present Sunyaev-Zel'dovich Effect (SZE) imaging observations of three
distant (z > 0.8) and highly X-ray luminous clusters of galaxies, Cl1226+33,
Cl0152-13 and MS1054-03. Two of the clusters, Cl1226+33 and Cl0152-13, were
recently discovered in deep ROSAT x-ray images. Their high X-ray luminosity
suggests that they are massive systems which, if confirmed, would provide
strong constraints on the cosmological parameters of structure formation
models. Our Sunyaev-Zel'dovich Effect data provide confirmation that they are
massive clusters similar to the well studied cluster MS1054-03. Assuming the
clusters have the same gas mass fraction as that derived from SZE measurements
of eighteen known massive clusters, we are able to infer their mass and
electron temperature from the SZE data. The derived electron temperatures are
9.8, 8.7, and 10.4 keV, respectively, and we infer total masses of ~2 x 10^14
h^-1 Msun within a radius of 65 arcsec (340 h^{-1} kpc) for all three clusters.
For Cl0152-13 and MS1054-03 we find good agreement between our SZE derived
temperatures and those inferred from X-ray spectroscopy. No X-ray derived
temperatures are available for Cl1226+33, and thus the SZE data provide the
first confirmation that it is indeed a massive system. The demonstrated ability
to determine cluster temperatures and masses from SZE observations without
access to X-ray data illustrates the power of using deep SZE surveys to probe
the distant universe.


title: Synthesis of Small and Large scale Dynamos

abstract:
  Using a closure model for the evolution of magnetic correlations, we uncover
an interesting plausible saturated state of the small-scale fluctuation dynamo
(SSD) and a novel anology between quantum mechanical tunneling and the
generation of large-scale fields. Large scale fields develop via the
$\alpha$-effect, but as magnetic helicity can only change on a resistive
timescale, the time it takes to organize the field into large scales increases
with magnetic Reynolds number. This is very similar to the results which obtain
from simulations using full MHD.


title:
A Gas-Kinetic Stability Analysis of Self-Gravitating and Collisional
  Particulate Disks with Application to Saturn's Rings

abstract:
  Linear theory is used to determine the stability of the self-gravitating,
rapidly (and nonuniformly) rotating, two-dimensional, and collisional
particulate disk against small-amplitude gravity perturbations. A gas-kinetic
theory approach is used by exploring the combined system of the Boltzmann and
the Poisson equations. The effects of physical collisions between particles are
taken into account by using in the Boltzmann kinetic equation a Krook model
integral of collisions modified to allow collisions to be inelastic. It is
shown that as a direct result of the classical Jeans instability and a secular
dissipative-type instability of small-amplitude gravity disturbances (e.g.
those produced by a spontaneous perturbation and/or a companion system) the
disk is subdivided into numerous irregular ringlets, with size and spacing of
the order of the Jeans length (= (4-6) mean epicyclic radius). The present
research is aimed above all at explaining the origin of various structures in
highly flattened, rapidly rotating systems of mutually gravitating particles.
In particular, it is suggested that forthcoming Cassini spacecraft
high-resolution images may reveal this kind of hyperfine of the order of 100 m
structure in the main rings A, B, and C of the Saturnian ring system.


title: Populating a cluster of galaxies - I. Results at z=0

abstract:
  We simulate the assembly of a massive rich cluster and the formation of its
constituent galaxies in a flat, low-density universe. Our most accurate model
follows the collapse, the star-formation history and the orbital motion of all
galaxies more luminous than the Fornax dwarf spheroidal, while dark halo
structure is tracked consistently throughout the cluster for all galaxies more
luminous than the SMC. Within its virial radius this model contains about 2.0e7
dark matter particles and almost 5000 distinct dynamically resolved galaxies.
Simulations of this same cluster at a variety of resolutions allow us to check
explicitly for numerical convergence both of the dark matter structures
produced by our new parallel N-body and substructure identification codes, and
of the galaxy populations produced by the phenomenological models we use to
follow cooling, star formation, feedback and stellar aging. This baryonic
modelling is tuned so that our simulations reproduce the observed properties of
isolated spirals outside clusters. Without further parameter adjustment our
simulations then produce a luminosity function, a mass-to-light ratio,
luminosity, number and velocity dispersion profiles, and a morphology-radius
relation which are similar to those observed in real clusters. In particular,
since our simulations follow galaxy merging explicitly, we can demonstrate that
it accounts quantitatively for the observed cluster population of bulges and
elliptical galaxies.


title:
Cosmic Microwave Background Polarization Signals from Tangled Magnetic
  Fields

abstract:
  Tangled, primordial cosmic magnetic fields create small rotational velocity
perturbations on the last scattering surface (LSS) of the cosmic microwave
background radiation (CMBR). For fields which redshift to a present value of
$B_0 = 3\times 10^{-9}$ Gauss, these vector modes are shown to generate
polarization anisotropies of order $0.1\mu K - 4 \mu K$ on small angular scales
($ 500 < l < 2000$), assuming delta function or a power law spectra with
$n=-1$. About 200 times larger signals result for $n=2$ spectra. Unlike
inflation generated, scalar modes, these signals are dominated by the odd
parity, B-type polarization, which could help in their detection.


title:
Exploring the formation and evolution of massive ellipticals with
  Extremely Red Objects

abstract:
  Extremely Red Objects (EROs) provide the important possibility to shed light
on the formation and evolution of the present-day massive ellipticals. On one
hand, they allow to select z>1 old passively evolving spheroidals and to
compare their abundance with the predictions of galaxy formation scenarios. On
the other hand, they provide the possibility to find dust obscured starbursts,
a fraction of which may trace the formation of proto-ellipticals at z>2. In
this paper, the most recent results on EROs are reviewed and the main
implications discussed.


title:
Decay of inhomogeneities from the spin-torsion fluctuations in the early
  stages of inflation

abstract:
  The spin-torsion fluctuations are shown to act as source of decay of
inhomogeneities in the early stages of inflationary de Sitter universe.This
seems to be a resul of the repulsive nature of the spin-torsion effects.This
result is shown through the investigation of the evolution equation of density
perturbations in Einstein-Cartan cosmology.We also show that it is possible to
place limits on torsion in the universe from the CMBR temperature anisotropy
from the computations we made.The decay of inhomogeneities is not enough
however to stop the structure formation as galaxies because the growth of
inhomogeneitis dominates the torsion effects and the only effect of torsion
seems to decrease very weakly the speed of formation of galaxies.


title: Terapixel Surveys for Cosmic Shear

abstract:
  The recent detections of cosmic shear signal announced by several groups have
demonstrated the feasibility of this challenging program and convinced astro-
nomers of its potential for cosmology. Cosmic shear analysis demands to handle
Gigabytes of data in order to probe several square degrees in subarcsecond deep
imaging mode. The success of these surveys is sensitive to the designs of the
observation strategy, the organization of the data reduction pipelines and the
links of the data base with surveys like X-ray or spectroscopic follow up. We
describe the cosmic shear surveys we have carried out at the VLT and at CFHT
and the way we handle this huge data set in a more general context including
the VIRMOS and the XMM-LSS surveys, and the future CMB surveys.


title:
The cepheid-like relationship between variability and luminosity
  explained within the ``cannonball model'' of Gamma-Ray bursts

abstract:
  I show how an empirical variability - luminosity relationship for prompt
gamma-ray bursts, first proposed by Fenimore and Ramirez-Ruiz, can be
understood as a special-relativistic beaming effect in the ``cannonball model''
of Dar and De R\'ujula. In this scenario the variability is a measure of the
direction of propagation and the Lorentz factor of the cannonball on which in
turn the apparent luminosity of the prompt GRB depends sensitively. The
observed absence of cosmological time dilation in the ``aligned peak test'' -
when using redshifts derived with this relation - is also explained. The most
direct evidence in favour of the cannonball model presented here is its correct
description for the observed relation between narrow-spike width and amplitude
within a given GRB. There seems to be an indication for cosmological time
dilation in the total duration of GRBs, as expected in the cannonball model.
Quantitative predictions for the luminosity function of GRBs and the
``spectral-lag luminosity relation'' are given.


title:
Possible direct method to determine the radius of a star from the
  spectrum of gravitational wave signals II : Spectra for various cases

abstract:
  We compute the spectrum and the waveform of gravitational waves generated by
the inspiral of a disk or a spherical like dust body into a Kerr black hole. We
investigate the effect of the radius R of the body on gravitational waves and
conclude that the radius is inferred from the gravitational wave signal
irrespective of (1) the form of the body (a disk or a spherical star) (2) the
location where the shape of the body is determined, (3) the orbital angular
momentum of the body, and (4) a black hole rotation. We find that when $R$ is
much larger than the characteristic length of the quasinormal mode frequency,
the spectrum has several peaks and the separation of the troughs $\Delta\omega$
is proportional to $R^{-1}$. Thus, we may directly determine the radius of a
star in a coalescing binary black hole - star system from the observed spectrum
of gravitational waves. For example, both trough frequency of neutron stars and
white dwarfs are within the detectable frequency range of some laser
interferometers and resonant type detectors so that this effect can be observed
in the future. We therefore conclude that the spectrum of gravitational waves
may provide us important signals in gravitational wave astronomy as in optical
astronomy.


title:
One-dimensional Electric Field Structure of an Outer Gap Accelerator -
  III. Location of the Gap and the Gamma-ray Spectrum

abstract:
  We investigate a stationary particle acceleration zone in the outer
magnetosphere of a spinning neutron star. The charge depletion due to a global
current causes a large electric field along the magnetic field lines. Migratory
electrons and/or positrons are accelerated by this field to radiate curvature
gamma-rays, some of which collide with the X-rays to materialize as pairs in
the gap. As a result of this pair-production cascade, the replenished charges
partially screen the electric field, which is self-consistently solved together
with the distribution of particles and gamma-rays. If no current is injected at
neither of the boundaries of the accelerator, the gap is located around the
so-called null surface, where the local Goldreich-Julian charge density
vanishes. However, we find that the gap position shifts outwards (or inwards)
when particles are injected at the inner (or outer) boundary. We apply the
theory to the nine pulsars of which X-ray fields are known from observations.
We show that the gap should be located near to or outside of the null surface
for the Vela pulsar and PSR B1951+32, so that their expected GeV spectrum may
be consistent with observations. We then demonstrate that the intrinsically
large TeV flux from the outer gap of PSR B0540-69 is absorbed by the
magnetospheric infrared photons to be undetectable. We also point out that the
electrodynamic structure and the resultant GeV emission properties of
millisecond pulsars are similar to young pulsars.


title:
Near-infrared spectroscopy of the circumnuclear star formation regions
  in M100: Evidence for sequential triggering

abstract:
  We present low resolution (R~450) K-band spectroscopy for 16 of the 43
circumnuclear star-forming knots in M100 identified by Ryder & Knapen (1999).
We compare our measurements of equivalent widths for the Br-gamma emission line
and CO 2.29 micron absorption band in each knot with the predictions of
starburst models from the literature, and derive ages and burst parameters for
the knots. The majority of these knots are best explained by the result of
short, localised bursts of star formation between 8 and 10 Myr ago. By
examining both radial and azimuthal trends in the age distribution, we present
a case for sequential triggering of star formation, most likely due to the
action of a large-scale shock. In an appendix, we draw attention to the fact
that the growth in the CO spectroscopic index with decreasing temperature in
supergiant stars is not as regular as is commonly assumed.


title: The Formation of Black-Hole X-Ray Transients

abstract:
  Studies of the observed characteristics of black-hole (BH) X-ray binaries can
be provide us with valuable information about the process of BH formation. In
this paper I address some of the aspects of our current understanding of BH
formation in binaries and point out some of the existing problems of current
theoretical models. In particular, the measured orbital periods and donor-star
properties indicate that a common-envelope phase appears to be a necessary
ingredient of the evolutionary history of observed BH X-ray transients, and
that it must be associated only with a modest orbital contraction. The timing
of this common-envelope phase is crucial in determining the final BH masses and
current evolutionary models of mass-losing massive stars place strong
constraints on the possible masses for immediate BH progenitors and wind mass
loss from helium stars. Last, it is interesting that, even in the absence of
any source of mass loss, the highest helium-star masses predicted by current
evolutionary models are still not high enough to account for the measured BH
mass in V404 Cyg (>10 solar masses). An alternative for the formation of
relatively massive BH may be provided by the evolutionary sequence proposed by
Eggleton & Verbunt (1986), which invokes hierarchical triples as progenitors of
BH X-ray binaries with low-mass companions.


title: Spectroscopy of Ultra Steep Spectrum Radio Sources

abstract:
  We present optical spectroscopy of 62 objects selected from several samples
of ultra steep spectrum (USS) radio sources. 46 of these are from our primary
catalog, consisting of 669 sources with radio spectral indices alpha < -1.30
(S_nu ~ nu^alpha); this first spectroscopic sub-sample was selected on the
basis of their faint optical and near-IR identifications. Most are identified
as narrow-lined radio galaxies with redshifts ranging from z=0.25 to z=5.19.
Ten objects are at z>3, nearly doubling the number of such sources known to
date. Four of the USS radio sources are identified with quasars, of which at
least three have very red spectral energy distributions. The source TN
J0936-2242 is identified with an extremely red object (ERO, R-K>5); both it and
a close companion are at z=1.479. The spectrum of the ERO closely resembles
that of previously discovered radio galaxies at z~1.5. Five sources show
continuum emission, but fail to show any clear emission or absorption features,
despite integrations of ~1 h with the Keck telescope. We suggest that these
objects could be (i) radio galaxies with faint emission lines in the ``redshift
desert'' at 1.5 <~ z <~ 2.3, (ii) radio galaxies with an obscured AGN, which
are dominated by a stellar continuum observed with insufficient S/N, or (iii)
pulsars. Three radio sources identified with faint objects in the K-band images
remain undetected in 50-90 min spectroscopic integrations with the Keck
telescope, and are possible z>7 candidates.


title: Cosmic Momentum Field and Mass Fluctuation Power Spectrum

abstract:
  We introduce the cosmic momentum field as a new measure of the large-scale
peculiar velocity and matter fluctuation fields. The momentum field is defined
as the peculiar velocity field traced and weighted by galaxies, and is equal to
the velocity field in the linear regime. We show that the radial component of
the momentum field can be considered as a scalar field with the power spectrum
which is practically 1/3 of that of the total momentum field. We present a
formula for the power spectrum directly calculable from the observed radial
peculiar velocity data. The momentum power spectrum is measured for the MAT
sample in the Mark III catalog of peculiar velocities of galaxies. Using the
momentum power spectrum we find the amplitude of the matter power spectrum is
6400^{+2800}_{-1800} and 4500^{+2000}_{-1300} \Omega^{-1.2} (h^{-1} Mpc)^{-3}
at the wavenumbers 0.049 and 0.074 h Mpc^{-1}, respectively, where \Omega is
the density parameter. The 68% confidence limits include the cosmic variance.
The measured momentum and density power spectra together indicate that the
parameter \beta_O = \Omega^{0.6}/b_O = 0.51^{+0.13}_{-0.08} or \Omega =
0.33^{+0.15}_{-0.09} b_O^{5/3} where b_O is the bias factor for optical
galaxies.


title:
Galaxy Cluster Gas Mass Fractions from Sunyaev-Zel'dovich Effect
  Measurements: Constraints on Omega_M

abstract:
  Using sensitive centimeter-wave receivers mounted on the Owens Valley Radio
Observatory and Berkeley-Illinois-Maryland-Association millimeter arrays, we
have obtained interferometric measurements of the Sunyaev-Zel'dovich (SZ)
effect toward massive galaxy clusters. We use the SZ data to determine the
pressure distribution of the cluster gas and, in combination with published
X-ray temperatures, to infer the gas mass and total gravitational mass of 18
clusters. The gas mass fraction, f_g, is calculated for each cluster, and is
extrapolated to the fiducial radius r_{500} using the results of numerical
simulations. The mean f_g within r_{500} is 0.081+0.009 -0.011/(h_{100}
(statistical uncertainty at 68% confidence level, assuming OmegaM=0.3,
OmegaL=0.7). We discuss possible sources of systematic errors in the mean f_g
measurement. We derive an upper limit for OmegaM from this sample under the
assumption that the mass composition of clusters within r_{500} reflects the
universal mass composition: Omega_M h < Omega_B/f_g. The gas mass fractions
depend on cosmology through the angular diameter distance and the r_{500}
correction factors.
  For a flat universe (OmegaL = 1 - OmegaM) and h=0.7, we find the measured gas
mass fractions are consistent with Omegam less than 0.40, at 68% confidence.
Including estimates of the baryons contained in galaxies and the baryons which
failed to become bound during the cluster formation process, we find OmegaM
\~0.25.


title: The Properties of High Redshift Galaxies

abstract:
  In recent years, a variety of techniques at optical, near-infrared, sub-mm,
and radio wavelengths have opened complementary windows on the high-redshift
Universe. Here we review the current understanding of the general properties of
the z>~2 galaxies detected in the optical (Lyman-break galaxies) and in the
sub-mm (SCUBA sources). We list some of the key questions that need to be
answered in order to understand the nature and evolution of the high-redshift
galaxies. Wherever possible, we present tentative answers given so far to those
questions, in particular on the low-redshift couterparts of the high-redshift
galaxies, on the impact of dust obscuration on the observed quantities, and on
physical characteristics of the high-z systems as inferred from observations.


title: X-ray transients in quiescence

abstract:
  Transient X-ray binaries remain in their quiescent state for a long time
(months to hundred years) and then bright up as the most powerful sources of
the X-ray sky. While it is clear that, when in outbursts, transient binaries
are powered by accretion, the origin of the low luminosity X-ray emission that
has been detected in the quiescent state has different interpretations and
provides the unique opportunity for testing different accretion regimes. In
this paper we concentrate on the various aspects of the accretion physics at
low rates onto compact objects. We describe the observational panorama of
quiescent emission for the three classes of X-ray transients and try to
interpret these data in light of the different regimes accessible at such low
mass inflow rates.


title: On the viewing angle to broad-lined radio galaxies

abstract:
  We address the nature of broad-lined radio galaxies, in particular their
radio axis orientation, using new, matched resolution, dual frequency radio
observations of a sample of twelve nearby broad-lined extragalactic 3C objects.
Radio spectral index and depolarisation asymmetries indicate that these objects
have a preferred orientation with respect to the observer. In addition, the
spectral asymmetries are suggestive of lower Doppler factors in the broad-lined
radio galaxies when compared to 3C quasars. This is in agreement with their
optical properties, and leads to the conclusion that some objects are lower
powered versions-at similar lines of sight-of the more distant quasars, whereas
others are at larger angles to the line of sight.


title: Mass profiles and anisotropies of early-type galaxies

abstract:
  We discuss the problem of using stellar kinematics of early-type galaxies to
constrain the galaxies' orbital anisotropies and radial mass profiles. We
demonstrate that compressing a galaxy's light distribution along the line of
sight produces approximately the same signature in the line-of-sight velocity
profiles as radial anisotropy. In particular, fitting spherically symmetric
dynamical models to apparently round, isotropic face-on flattened galaxies
leads to a spurious bias towards radial orbits in the models, especially if the
galaxy has a weak face-on stellar disk. Such face-on stellar disks could
plausibly be the cause of the radial anisotropy found in spherical models of
intermediate luminosity ellipticals such as NGC 2434, NGC 3379 and NGC 6703.
  In the light of this result, we use simple dynamical models to constrain the
outer mass profiles of a sample of 18 round, early-type galaxies. The galaxies
follow a Tully-Fisher relation parallel to that for spiral galaxies, but
fainter by at least 0.8 mag (I-band) for a given mass. The most luminous
galaxies show clear evidence for the presence of a massive dark halo, but the
case for dark haloes in fainter galaxies is more ambiguous. We discuss the
observations that would be required to resolve this ambiguity.


title: Supernovae as stellar objects

abstract:
  Type Ia supernovae (SN Ia) are generally believed to be the result of the
thermonuclear disruption of Chandrasekhar-mass carbon-oxygen white dwarfs,
mainly because such thermonuclear explosions can account for the right amount
of nickel, which is needed to explain the light curves and the late-time
spectra, and the abundances of intermediate-mass nuclei which dominate the
spectra near maximum light. Because of their enormous brightness and apparent
homogeneity SN Ia have become an important tool to measure cosmological
parameters.
  In this article the present understanding of the physics of thermonuclear
explosions is reviewed. In particular, we focus our attention on subsonic
("deflagration") fronts, i.e. we investigate fronts propagating by heat
diffusion and convection rather than by compression. Models based upon this
mode of nuclear burning have been applied very successfully to the SN Ia
problem, and are able to reproduce many of their observed features remarkably
well. However, the models also indicate that SN Ia may differ considerably from
each other, which is of importance if they are to be used as standard candles.


title: K band monitoring of GRS 1915+105 during 1999/2000

abstract:
  We report on long-term K band photometry of the galactic microquasar GRS
1915+105 since March 1999. We see variations of more than 1 mag, which are
seemingly correlated with variations in X-ray intensity and spectral slope.


title: Identification of the donor in GRS 1915+105

abstract:
  We report on the results of medium-resolution spectroscopy of GRS 1915+105 in
the H and K band using the 8m VLT at ESO. We clearly identify absorption
bandheads from CO12 and CO13. Together with other features this results in a
classification of the donor as a K-M III star.


title: The Cosmological Evolution of BL Lacertae Objects

abstract:
  We review the main results from several radio, X-ray and multi-frequency
surveys on the topic of cosmological evolution of BL Lacertae objects. Updated
findings on BL Lac evolution following the recent identification of many
sources in the ``Sedentary Multi-Frequency survey'' are also discussed. By
means of extensive Monte Carlo simulations we test some possible explanations
for the peculiar cosmological evolution of BL Lacs. We find that a dependence
of the relativistic Doppler factor on radio luminosity (as expected within the
beaming scenario) may induce low values of V/V_max and that both edge effects
at the low luminosity end of the BL Lacs radio luminosity function, and
incompleteness at faint optical magnitudes may be the cause of the low V/V_max
found for extreme HBL sources in X-ray selected samples.


title: Relativistic corrections to fractal analyses of the galaxy distribution

abstract:
  The effect of curvature on the results of fractal analyses of the galaxy
distribution is investigated. We show that, if the universe satisfies the
criteria of a wide class of parabolic homogeneous models, the observers
measuring the fractal index with the integrated conditional density procedure
may use the Hubble formula, without having to allow for curvature, out to
distances of 600 Mpc, and possibly far beyond. This contradicts a previous
claim by Ribeiro (1995) that, in the Einstein-de Sitter case, relativistic
corrections should be taken into account at much smaller scales. We state for
the class of cosmological models under study, and give grounds for conjecture
for others, that the averaging procedure has a smoothing effect and that,
therefore, the redshift-distance relation provides an upper limit to the
relativistic corrections involved in such analyses.


title: On the pre-RLO spin-orbit couplings in LMXBs

abstract:
  We investigate the effect of orbital decay caused by nuclear expansion of a
(sub)giant star in synchronous binary system. We compare this effect with the
presence of a magnetic stellar wind and show that the additional transfer of
orbital angular momentum into spin angular momentum is relatively important --
especially since it has been shown that the effect of magnetic braking
saturates at short orbital periods.


title: Supernova Science with an Advanced Compton Telescope

abstract:
  Gamma-ray line emission is a direct probe of the nucleosynthesis that occurs
in Type Ia supernovae. In this work we describe the wealth of information
obtainable from observations of this emission. Advanced Compton telescope
designs are being studied by the Naval Research Laboratory, with the goal being
the construction of a telescope which would be capable of detecting SNe Ia to
distances in excess of 100 Mpc. We describe the instrument capabilities and the
design issues that are being addressed. We assume a SN Ia rate and quantify the
frequency at which an advanced Compton telescope could detect, discriminate
between, and diagnose Type Ia supernovae. From these estimates, we argue that
an advanced Compton telescope would be a powerful astrophysical tool.


title:
ATCA search for 21 cm emission from a candidate damped Ly-$\alpha$
  absorber at z = 0.101

abstract:
  We report a deep search for 21 cm emission/absorption from the $z \sim 0.101$
candidate damped Lyman-$\alpha$ system towards PKS 0439-433, using the
Australia Telescope Compact Array (ATCA). The spectrum shows a weak absorption
feature --- at the $3.3 \sigma$ level --- which yields a lower limit of 730 K
on the spin temperature of the system. No HI emission was detected: the
$3\sigma$ upper limit on the HI mass of the absorber is $2.25 \times 10^9
M_{\odot}$, for a velocity spread of $\sim 70$ km s$^{-1}$. The low HI mass and
the high spin temperature seem to rule out the possibility that the absorber is
a large gas-rich spiral galaxy.


title:
3D MHD Simulations of Radio Galaxies Including Nonthermal Electron
  Transport

abstract:
  We report on an effort to study the connections between dynamics in simulated
radio galaxy plasma flows and the properties of nonthermal electron populations
carried in those flows. To do this we have introduced a new numerical scheme
for electron transport that allows a much more detailed look at this problem
than has been possible before. Especially when the dynamics is fully three
dimensional the flows are generally chaotic in the cocoon, and the jet itself
can flail about violently. The bending jet can pinch itself off and redirect
itself to enhance its penetration of the ambient medium. These behaviors often
eliminate the presence of a strong jet termination shock, which is assumed
present in all modern cartoon models of the RG phenomenon. Instead a much more
complex ``shock web'' forms near the end of the jet that leads to a far less
predictable pattern of particle acceleration. Similarly, the magnetic fields in
these flows are highly filamented, as well as spatially and temporally
intermittent. This leads to a very localized and complex pattern of synchrotron
aging for relativistic electron populations, which makes it difficult to use
properties of the electron spectrum to infer the local rate of aging.


title:
Nonthermal Emission in Radio Galaxies from Simulated Relativistic
  Electron Transport in 3D MHD Flows

abstract:
  We perform a series of so-called ``synthetic observations'' on a set of 3D
MHD jet simulations which explicitly include energy-dependent transport of
relativistic electrons, as described in the companion paper by Jones,
Tregillis, & Ryu. Analyzing them in light of the complex source dynamics and
energetic particle distributions described in that paper, we find that the
standard model for radiative aging in radio galaxies does not always adequately
reflect the detailed source structure.


title: Correlations of Cosmic Tidal Fields

abstract:
  We study correlations amongst tidal fields originated by the large-scale
distribution of matter in the Universe. The two-point tidal correlation is
described as a rank-4 tensor, whose elements can be written in terms of four
fundamental scalar functions ranging, with respect the spatial separation, from
purely transversal to purely longitudinal correlations. Tidal fields, both on
galaxy and cluster scales, reveal to be correlated over distances larger than
the mass-density correlation lenght, though traceless tidal fields show
anti-correlation between diagonal terms along orthogonal directions. The
cross-correlation between mass and tidal field is also analyzed. These results
are relevant for galaxy formation and the interpretation of large-scale weak
lensing phenomena.


title:
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning
  Data V. Hobby-Eberly Telescope Observations

abstract:
  We report the discovery of 27 quasars with redshifts between 3.58 and 4.49.
The objects were identified as high-redshift candidates based on their colors
in Sloan Digital Sky Survey commissioning data. The redshifts were confirmed
with low resolution spectra obtained at the Hobby-Eberly Telescope. The
quasars' $i^*$ magnitudes range from 18.55 to 20.97. Nearly 60% of the quasar
candidates observed are confirmed spectroscopically as quasars. Two of the
objects are Broad Absorption Line quasars, and several other quasars appear to
have narrow associated absorption features.


title:
EUV and soft X-rays from clusters of galaxies - the `cluster
  soft-excess' phenomenon

abstract:
  Clusters of galaxies are strong emitters of EUV and soft X-rays substantially
in excess of the contribution from the hot intra-cluster medium at X-ray
temperatures. After the initial discovery of EUV excess emission in the Virgo
cluster, the phenomenon was reported also for the Coma, A1795 and A2199
clusters. Recent reobservations confirmed the finding, and further searches on
a large sample of nearby galaxy clusters are clearly revealing the cosmological
impact of the discovery.


title: The Luminosity Function of Galaxies in SDSS Commissioning Data

abstract:
  During commissioning observations, the Sloan Digital Sky Survey (SDSS) has
produced one of the largest existing galaxy redshift samples selected from CCD
images. Using 11,275 galaxies complete to r^* = 17.6 over 140 square degrees,
we compute the luminosity function of galaxies in the r^* band over a range -23
< M < -16 (for h=1). The result is well-described by a Schechter function with
parameters phi_* = 0.0146 +/- 0.0012 h^3 Mpc^{-3}, M_* = -20.83 +/- 0.03, and
alpha = -1.20 +/- 0.03. The implied luminosity density in r^* is j = (2.6 +/-
0.3) x 10^8 h L_sun Mpc^{-3}. The surface brightness selection threshold has a
negligible impact for M < -18. We measure the luminosity function in the u^*,
g^*, i^*, and z^* bands as well; the slope at low luminosities ranges from
alpha=-1.35 to alpha=-1.2. We measure the bivariate distribution of r^*
luminosity with half-light surface brightness, intrinsic color, and morphology.
High surface brightness, red, highly concentrated galaxies are on average more
luminous than low surface brightness, blue, less concentrated galaxies. If we
synthesize results for R-band or b_j-band using the Petrosian magnitudes with
which the SDSS measures galaxy fluxes, we obtain luminosity densities 2.0 times
that found by the Las Campanas Redshift Survey in R and 1.4 times that found by
the Two-degree Field Galaxy Redshift Survey in b_j. We are able to reproduce
the luminosity functions obtained by these surveys if we also mimic their
isophotal limits for defining galaxy magnitudes, which are shallower and more
redshift dependent than the Petrosian magnitudes used by the SDSS. (Abridged)


title:
Numerical and Analytical Predictions for the Large-Scale
  Sunyaev-Zel'dovich Effect

abstract:
  The hot gas embedded in the large-scale structures in the Universe produces
secondary fluctuations in the Cosmic Microwave Background (CMB). Because it is
proportional to the gas pressure integrated along the line of sight, this
effect, the thermal Sunyaev-Zel'dovich (SZ) effect, provides a direct measure
of large-scale structure and of cosmological parameters. We study the
statistical properties of this effect using both hydrodynamical simulations and
analytical predictions from an extended halo model. The Adaptive Mesh
Refinement scheme, used in the newly developed code RAMSES, provides a dynamic
range of 4 order of magnitudes, and thus allows us to significantly improve
upon earlier calculations. After accounting for the finite mass resolution and
box size of the simulation, we find that the halo model agrees well with the
simulations. We discuss and quantify the uncertainty in both methods, and thus
derive an accurate prediction for the SZ power spectrum in the 10^2<l<10^5
range of multipole. We show how this combined analytical and numerical approach
is essential for accuracy, and useful for the understanding of the physical
processes and scales which contribute to large-scale SZ anisotropies.


title: Power Spectrum Covariance of Weak Gravitational Lensing

abstract:
  Weak gravitational lensing observations probe the spectrum and evolution of
density fluctuations and the cosmological parameters which govern them. At low
redshifts, the non-linear gravitational evolution of large scale structure
produces a non-Gaussian covariance in the shear power spectrum measurements
that affects their translation into cosmological parameters. Using the dark
matter halo approach, we study the covariance of binned band power spectrum
estimates and the four point function of the dark matter density field that
underlies it. We compare this semi-analytic estimate to results from N-body
numerical simulations and find good agreement. We find that for a survey out to
z ~ 1, the power spectrum covariance increases the errors on cosmological
parameters determined under the Gaussian assumption by about 15%.


title: Protoneutron star in the Relativistic Mean - Field Theory

abstract:
  In this review the basic properties of nonrotating and slowly rotating
protoneutron stars in the relativistic mean-field approach are discussed. The
equation of state is the main input to the structure equations. The TM1
parameter set extended to the case of finite temperature is used to obtain the
mass-radius relation for protoneutron stars. The occurrence of unstable areas
in the mass-radius relation are presented. This allows for the existence of
distinctively different evolutionary of tracks of the protoneutron stars. The
low density protoneutron star configurations are estimated. The obtained stable
configurations for the fixed lepton number Y_L=0.4 are compared with ones
obtained for the fixed proton fraction Y_P=0.1776.


title:
Near-IR Spectroscopy and Population Synthesis of Super Star Clusters in
  NGC 1569

abstract:
  We present H- and K-band NIRSPEC spectroscopy of super star clusters (SSCs)
in the irregular starburst galaxy NGC 1569, obtained at the Keck Observatory.
We fit these photospheric spectra to NextGen model atmospheres to obtain
effective spectral types of clusters, and find that the information in both H-
and K-band spectra is necessary to remove degeneracy in the fits. The light of
SSC B is unambiguously dominated by K0 supergiants (T_eff=4400 +- 100 K, log
g=0.5 +- 0.5). The double cluster SSC A has higher T_eff (G5) and less tightly
constrained surface gravity (log g=1.3 +- 1.3), consistent with a mixed stellar
population dominated by blue Wolf-Rayet stars and red supergiants. We predict
the time evolution of infrared spectra of SSCs using Starburst99 population
synthesis models coupled with empirical stellar spectral libraries (at solar
metallicity). The resulting model sequence allows us to assign ages of 15-18
Myr for SSC B and 18-21 Myr for SSC A.


title: Evolution of Cluster Early-Type Galaxies

abstract:
  The slow evolution of the M/L ratios, colors, and line strengths of cluster
early-type galaxies to z=1 suggests that their stars were formed at very high
redshift. At the same time, morphological studies of distant clusters indicate
significant evolution in the early-type galaxy population. Striking evidence
for strong morphological evolution in clusters is the discovery of a large
number of red merger systems in the cluster MS 1054-03 at z=0.83. The presence
of these mergers is qualitatively consistent with predictions from hierarchical
galaxy formation models, and is direct evidence against an early collapse for
all early-type galaxies. In most of the mergers there is no evidence for strong
star formation. Therefore the mean stellar ages of the merger products will be
much older than the ``assembly age'', and do not violate the constraints on the
star formation epoch of early-type galaxies imposed by the color-magnitude
relation and the Fundamental Plane.


title:
Light Curves and Spectra of Dust Echoes From Gamma-Ray Bursts and their
  Afterglows: Continued Evidence that GRB 970228 is Associated with a Supernova

abstract:
  The relative brightening and reddening of the optical afterglows of GRB
970228 and GRB 980326 around 20 - 30 days after these bursts have been
attributed to supernovae, which are red (blueward of their spectral peak), and
which peak in time after about 20(1+z) days. However, this direct evidence for
a GRB/SN connection has recently been challenged. It has been suggested that
the late afterglows of these bursts can be explained by dust echoes, of which
we consider two cases: (1) the scattering of light from the afterglow (the
forward shock), the optical flash (the reverse shock), and/or optical light
from the burst itself by a shell of dust at a radius R from the progenitor, and
(2) the absorption and thermal re-emission of this light by this shell of dust.
In this paper, we model and compute dust echo light curves and spectra for both
cases. Although the late-time afterglow of GRB 980326 was not sufficiently well
sampled to rule out a dust echo description, we find that the late-time
afterglow of GRB 970228 cannot be explained by a dust echo.


title:
Evolution of Clusters of Galaxies II: Dependence on Initial Cluster
  Model

abstract:
  We investigated the evolution of clusters of galaxies using self-consistent
N-body simulations. We varied the initial model of galaxies and clusters, and
studied the dependence of evolution on initial conditions. We found that the
growth rate of the common halo depends only weakly on galaxy models. On the
other hand, the growth rate depends strongly on cluster models. Initially the
growth rate is higher for cluster models with higher central density. However,
this high growth rate drops in a few crossing times of the cluster, and after
several crossing times, roughly half of the total mass is in the common halo in
all models we considered. In the central region of clusters density cusps with
the profile \rho ~ r^{-1.2} develops regardless of the models of clusters and
galaxies. We also found that the galaxies evolved so as to satisfy the relation
between the masses of galaxies m_{gx} and their velocity dispersion \sigma_{gx}
expressed as m_{gx} \propto \sigma_{gx}^{3~4} for all galaxy models as a
consequence of their dynamical evolution through galaxy-galaxy interactions. We
discuss the relation between our result and the observed Faber-Jackson
relation.


title: High-sensitivity observations of solar flare decimeter radiation

abstract:
  A new acousto-optic radio spectrometer has observed the 1 - 2 GHz radio
emission of solar flares with unprecedented sensitivity. The number of detected
decimeter type III bursts is greatly enhanced compared to observations by
conventional spectrometers observing only one frequency at the time. The
observations indicate a large number of electron beams propagating in dense
plasmas. For the first time, we report weak, reversed drifting type III bursts
at frequencies above simultaneous narrowband decimeter spikes. The type III
bursts are reliable signatures of electron beams propagating downward in the
corona, apparently away from the source of the spikes. The observations
contradict the most popular spike model that places the spike sources at the
footpoints of loops. Conspicuous also was an apparent bidirectional type U
burst forming a fish-like pattern. It occurs simultaneously with an intense
U-burst at 600-370 MHz observed in Tremsdorf. We suggest that it intermodulated
with strong terrestrial interference (cellular phones) causing a spurious
symmetric pattern in the spectrogram at 1.4 GHz. Symmetric features in the 1 -
2 GHz range, some already reported in the literature, therefore must be
considered with utmost caution.


title:
New constraints on the cosmic mid-infrared background using TeV
  gamma-ray astronomy

abstract:
  Very high energy gamma-ray data obtained by CAT and HEGRA from active
galactic nucleus Mkn 501 are used to constrain the cosmic Mid-Infrared
background. While the entire infrared and submillimeter spectrum shape based on
models has been fixed and the density scaled as a whole in previous studies,
recent measures on the low and high energy infrared background are extensively
used in this paper. In this original approach, the infrared distribution is
only varied in the unexplored 3.5-100 microns region. With conservative
hypothesis on the intrinsic spectra of Mkn 501, an upper limit of 4.7
nW.m-2.sr-1 between 5 and 15 microns is derived, which is very close to the
lower limit inferred from deep ISOCAM cosmological surveys at 15 microns. This
result is shown to be independent of the exact density of the lambda < 3.5
microns and lambda > 100 microns infrared distribution within the uncertainties
of the measurements. Moreover, the study presented here rules out a complete
extragalactic origin for the 60 microns excess found by Finkbeiner et al.
(2000).


title:
The initial conditions of isolated star formation: IV - C18O
  observations and modelling of the pre-stellar core L1689B

abstract:
  We present C18O observations of the pre-stellar core L1689B, in the (J=3-2)
and (J=2-1) rotational transitions, taken at the James Clerk Maxwell Telescope
in Hawaii. We use a lambda-iteration radiative transfer code to model the data.
We adopt a similar form of radial density profile to that which we have found
in all pre-stellar cores, with a `flat' inner profile, steepening towards the
edge, but we make the gradient of the `flat' region a free parameter. We find
that the core is close to virial equilibrium, but there is tentative evidence
for core contraction. We allow the temperature to vary with a power-law form
and find we can consistently fit all of the CO data with an inverse temperature
gradient that is warmer at the edge than the centre. However, when we combine
the CO data with the previously published millimetre data we fail to find a
simultaneous fit to both data-sets without additionally allowing the CO
abundance to decrease towards the centre. This effect has been observed
qualitatively many times before, as the CO freezes out onto the dust grains at
high densities, but we quantify the effect. Hence we show that the combination
of mm/submm continuum and spectral line data is a very powerful method of
constraining the physical parameters of cores on the verge of forming stars.