title: Observational Tests of FRW World Models

abstract:
  Observational tests for the Cosmological Principle are reviewed. Assuming the
FRW metric we then summarize estimates of cosmological parameters from various
data sets, in particular the Cosmic Microwave Background and the 2dF galaxy
redshift survey. These and other analyses suggest a best-fit Lambda-Cold Dark
Matter model with Omega_m = 1 - Omega_lambda = 0.3 and H_0 = 70 km/sec/Mpc. It
is remarkable that different measurements converge to this `concordance model',
although it remains to be seen if the two main components of this model, the
dark matter and the dark energy, are real entities or just `epicycles'. We
point out some open questions related to this fashionable model.


title:
Using Cepheids to determine the galactic abundance gradient I. The solar
  neighbourhood

abstract:
  A number of studies of abundance gradients in the galactic disk have been
performed in recent years. The results obtained are rather disparate: from no
detectable gradient to a rather significant slope of about -0.1 dex kpc -1. The
present study concerns the abundance gradient based on the spectroscopic
analysis of a sample of classical Cepheids. These stars enable one to obtain
reliable abundances of a variety of chemical elements. Additionally, they have
well determined distances which allow an accurate determination of abundance
distributions in the galactic disc. Using 236 high resolution spectra of 77
galactic Cepheids, the radial elemental distribution in the galactic disc
between galactocentric distances in the range 6-11 kpc has been investigated.
Gradients for 25 chemical elements (from carbon to gadolinium) are derived...


title: Measuring the Equation-of-state of the Universe: Pitfalls and Prospects

abstract:
  We explore various pitfalls and challenges in determining the
equation-of-state (w) of dark energy component that dominates the universe and
causes the current accelerated expansion. We demonstrated in an earlier paper
the existence of a degeneracy that makes it impossible to resolve well the
value of w or its time-derivative with supernovae data. Here we consider
standard practices, such as assuming priors that w is constant or greater than
-1, and show that they also can lead to gross errors in estimating the true
equation-of-state. We further consider combining measurements of the cosmic
microwave background anisotropy and the Alcock-Paczynski test with supernovae
data and find that the improvement in resolving the time-derivative of w is
marginal, although the combination can constrain its present value perhaps to
20 percent uncertainty.


title:
Dusty Acoustic Turbulence in the Nuclear Disks of two LINER Galaxies NGC
  4450 and NGC 4736

abstract:
  The structure of dust spirals in the nuclei of the SAab-type Liner galaxies
NGC 4450 and NGC 4736 is studied using archival HST PC images. The spirals are
typically only several hundredths of a magnitude fainter than the neighboring
disks, so unsharp mask techniques are used to highlight them. The ambient
extinction is estimated to be less than 0.1 mag from the intensity decrements
of the dust features and from the spiral surface filling factor, which is about
constant for all radii and sizes. The nuclear dust spirals differ from
main-disk spirals in several respects: the nuclear spirals have no associated
star formation, they are very irregular with both trailing and leading
components that often cross, they become darker as they approach the center,
they completely fill the inner disks with a constant areal density, making the
number of distinct spirals (the azimuthal wavenumber m) increase linearly with
radius, and their number decreases with increasing arm width as a power law.
Fourier transform power spectra of the spirals, taken in the azimuthal
direction, show a power law behavior with a slope of -5/3 over the range of
frequencies where the power stands above the pixel noise. This is the same
slope as that found for the one-dimensional power spectra of HI emission in the
Large Magellanic Cloud, and also the slope expected for a thin turbulent disk.
All of these properties suggest that the dust spirals are a manifestation of
acoustic turbulence in the inner gas disks of these galaxies. Such turbulence
should dissipate orbital energy and transfer angular momentum outward, leading
to a steady accretion of gas toward the nucleus.


title:
A Fractal Origin for the Mass Spectrum of Interstellar Clouds: II. Cloud
  Models and Power Law Slopes

abstract:
  Three-dimensional fractal models on grids of 200**3 pixels are generated from
the inverse Fourier transform of noise with a power law cutoff, exponentiated
to give a log normal distribution of density. The fractals are clipped at
various intensity levels and the mass and size distribution functions of the
clipped peaks and their subpeaks are determined. These distribution functions
are analogous to the cloud mass functions determined from maps of the fractal
interstellar medium using various thresholds for the definition of a cloud. The
model mass functions are found to be power laws with powers ranging from -1.6
to -2.4 in linear mass intervals as the clipping level increases from 0.03 to
0.3 of the peak intensity. The low clipping value gives a cloud filling factor
of 0.1 and should be a good model for molecular cloud surveys. The agreement
between the mass spectrum of this model and the observed cloud and clump mass
spectra suggests that a pervasively fractal interstellar medium can be
interpreted as a cloud/intercloud medium if the peaks of the fractal intensity
distribution are taken to be clouds. Their mass function is a power law even
though the density distribution function in the gas is a log-normal. This is
because the size distribution function of the clipped clouds is a power law,
and with clipping, each cloud has about the same average density. A similar
result would apply to projected clouds that are clipped fractals, giving nearly
constant column densities for power law mass functions. The steepening of the
mass function for higher clip values suggests a partial explanation for the
steeper slope of the mass functions for star clusters and OB associations,
which sample denser regions of interstellar gas.


title:
Distant Cluster Hunting II: A comparison of X-ray and optical cluster
  detection techniques and catalogs from the ROX Survey

abstract:
  We present and analyze the optical and X-ray catalogs of moderate-redshift
cluster candidates from the ROSAT Optical X-ray Survey, or ROXS. The survey
covers 4.8 square degrees (23 ROSAT PSPC pointings). The cross-correlated
cluster catalogs were constructed by comparing two independent catalogs
extracted from the optical and X-ray bandpasses, using a matched filter
technique for the optical data and a wavelet technique for the X-ray data. We
cross-id cluster candidates in each catalog. In Paper II we present the cluster
catalogs and a numerical simulation of ROXS. We also present color-magnitude
plots for several cluster candidates, and examine the prominence of the red
sequence in each. We find that the X-ray clusters analyzed in this way do not
all have a prominent red sequence. We conclude that while the red sequence may
be distinct for massive, virialized clusters, it may be less so for lower-mass
clusters at even moderate redshifts. Multiple, complementary methods of
selecting and defining clusters may be essential, particularly at high redshift
where all methods run into completeness limits, incomplete understanding of
physical evolution, and projection effects.


title:
Distant Cluster Hunting I: A Comparison Between the Optical and X-ray
  Luminosity Functions from an Optical/X-ray Survey

abstract:
  We present a comparison of X-ray and optical luminosities and luminosity
functions of cluster candidates from a joint optical/X-ray survey, the ROSAT
Optical X-Ray Survey. Completely independent X-ray and optical catalogs of 23
ROSAT fields (4.8 deg2) were created by a matched-filter optical algorithm and
by a wavelet technique in the X-ray. We directly compare the results of the
optical and X-ray selection techniques. The matched-filter technique detected
74% (26 out of 35) of the most reliable cluster candidates in the
X-ray-selected sample; the remainder could be either constellations of X-ray
point sources or z>1 clusters. The matched-filter technique identified
approximately 3 times the number of candidates (152 candidates) found in the
X-ray survey of nearly the same sky (57 candidates). While the estimated
optical and X-ray luminosities of clusters of galaxies are correlated, the
intrinsic scatter in this relationship is very large. We can reproduce the
number and distribution of optical clusters with a model defined by the X-ray
luminosity function and by an LX Lambda cl relation if H0=75 km s-1 Mpc-1 and
if the LX Lambda cl relation is steeper than the expected LX Lambda 2cl. On
statistical grounds, a bimodal distribution of X-ray luminous and X-ray faint
clusters is unnecessary to explain our observations. Follow-up work is required
to confirm whether the clusters without bright X-ray counterparts are simply
X-ray faint for their optical luminosity because of their low mass or youth or
are a distinct population of clusters that do not, for some reason, have dense
intracluster media. We suspect that these optical clusters are low-mass
systems, with correspondingly low X-ray temperatures and luminosities, or that
they are not yet completely virialized systems.


title: Gravitational Microlensing Near Caustics I: Folds

abstract:
  We study the local behavior of gravitational lensing near fold catastrophes.
Using a generic form for the lensing map near a fold, we determine the
observable properties of the lensed images, focusing on the case when the
individual images are unresolved, i.e., microlensing. Allowing for images not
associated with the fold, we derive analytic expressions for the photometric
and astrometric behavior near a generic fold caustic. We show how this form
reduces to the more familiar linear caustic, which lenses a nearby source into
two images which have equal magnification, opposite parity, and are equidistant
from the critical curve. In this case, the simplicity and high degree of
symmetry allows for the derivation of semi-analytic expressions for the
photometric and astrometric deviations in the presence of finite sources with
arbitrary surface brightness profiles. We use our results to derive some basic
properties of astrometric microlensing near folds, in particular we predict for
finite sources with uniform and limb darkening profiles, the detailed shape of
the astrometric curve as the source crosses a fold. We find that the
astrometric effects of limb darkening will be difficult to detect with the
currently planned accuracy of the Space Interferometry Mission. We verify our
results by numerically calculating the expected astrometric shift for the
photometrically well-covered Galactic binary lensing event OGLE-1999-BUL-23,
finding excellent agreement with our analytic expressions. Our results can be
applied to any lensing system with fold caustics, including Galactic binary
lenses and quasar microlensing.


title: Superhump-like variation during the anomalous state of SU UMa

abstract:
  We observed an anomalously outbursting state of SU UMa which occurred in
1992. Time-resolved photometry revealed the presence of signals with a period
of 0.0832 +/- 0.0019 d, which is 3.6 sigma longer than the orbital period
(0.07635 d) of this system. We attributed this signal to superhumps, based on
its deviation from the orbital period and its characteristic profile. During
this anomalous state of SU UMa, normal outbursts were almost suppressed, in
spite of relatively regular occurrences of superoutbursts. We consider that an
ensuing tidally unstable state following the preceding superoutburst can be a
viable mechanism to effectively suppress normal outbursts, resulting in an
anomalously outbursting state.


title: NGC 1399: a complex dynamical case

abstract:
  Evidence for a disturbed velocity structure in the outer regions of the
galaxy NGC1399 comes from a re-analysis of the planetary nebulae data from
Arnaboldi et al. (1994). We find a strong rotation along a P.A.=140 degrees for
R<=140'' which is followed by a rapid drop off at larger radii, where the
velocity dispersion starts to increase. This kinematical behavior can be
interpreted as an indication for an interaction scenario. Interaction is
advocated in previous analysis of the halo regions of this system, based on
different dynamical tracers such as globular clusters and X-rays, but in all
these studies the mass distribution is derived under the equilibrium
hypothesis, which is not appropriate when an interaction takes place. Here we
attempt a non-equilibrium dynamical analysis of NGC1399: with a simple model
and under the impulse approximation, we show that the observed kinematics is
consistent with an energy injection caused by a flyby encounter of NGC 1399
with the nearby system NGC 1404. In this approach, we find a mass-to-light
ratio, M/L_B=26 within R=400'', which is about half of that requested when
equilibrium is assumed, i.e. M/L_B=56.


title:
Observational Mass-to-Light Ratio of Galaxy Systems: from Poor Groups to
  Rich Clusters

abstract:
  We study the mass-to-light ratio of galaxy systems from poor groups to rich
clusters, and present for the first time a large database for useful
comparisons with theoretical predictions. We extend a previous work, where B_j
band luminosities and optical virial masses were analyzed for a sample of 89
clusters. Here we also consider a sample of 52 more clusters, 36 poor clusters,
7 rich groups, and two catalogs, of about 500 groups each, recently identified
in the Nearby Optical Galaxy sample by using two different algorithms. We
obtain the blue luminosity and virial mass for all systems considered. We
devote a large effort to establishing the homogeneity of the resulting values,
as well as to considering comparable physical regions, i.e. those included
within the virial radius. By analyzing a fiducial, combined sample of 294
systems we find that the mass increases faster than the luminosity: the linear
fit gives M\propto L_B^{1.34 \pm 0.03}, with a tendency for a steeper increase
in the low--mass range. In agreement with the previous work, our present
results are superior owing to the much higher statistical significance and the
wider dynamical range covered (about 10^{12}-10^{15} M_solar). We present a
comparison between our results and the theoretical predictions on the relation
between M/L_B and halo mass, obtained by combining cosmological numerical
simulations and semianalytic modeling of galaxy formation.


title: Galactic orbits of stars with planets

abstract:
  We have reconstructed the galactic orbits of the parent stars of exoplanets.
For comparison, we have recalculated the galactic orbits of stars from the
Edvardsson et al.(1993) catalog. A comparison between the two samples indicates
that stars with planets are not kinematically peculiar. At each perigalactic
distance stars with planets have a metallicity systematically larger than the
average for the comparison sample. We argue that this result favors scenarios
where the presence of planets is the cause of the higher metallicity of stars
with planets.


title: Signatures of kinetic and magnetic helicity in the CMBR

abstract:
  P and CP violation in cosmology can be manifested as large-scale helical
velocity flows in the ambient plasma and as primordial helical magnetic fields.
We show that kinetic helicity at last scattering leads to
temperature-polarization correlations ($C_l^{TB}$ and $C_l^{EB}$) in the cosmic
microwave background radiation (CMBR) and calculate the magnitude of the
effect. Helical primordial magnetic fields, expected from cosmic events such as
electroweak baryogenesis, can lead to helical velocity flows and hence to
non-vanishing correlations of the temperature and B-type polarization. However
we show that the magnitude of the induced helical flow is unobservably small
because the helical component of a magnetic field is almost force-free. We
discuss an alternate scheme for extracting the helicity of a stochastically
homogeneous and isotropic primordial magnetic field using observations of the
CMBR. The scheme involves constructing Faraday rotation measure maps of the
CMBR and thus determining the sum of the helical and non-helical components of
the primordial magnetic field. The power spectrum of B-type polarization
fluctuations, on the other hand, are sensitive only to the non-helical
component of the primordial magnetic field. The primordial magnetic helicity
can then be derived by combining these two sets of observations.


title: Is Vacuum Decay Significant in Ekpyrotic and Cyclic Models?

abstract:
  It has recently been argued that bubble nucleation in ekpyrotic and cyclic
cosmological scenarios can lead to unacceptable inhomogeneities unless certain
constraints are satisfied. In this paper we show that this is not the case. We
find that bubble nucleation is completely negligible in realistic models.


title:
Luminosities of [O III] and Hydrogen Balmer lines in nova shells years
  and decades after outburst

abstract:
  The evolution of the luminosity of nova shells in the century following the
nova outburst is studied for the lines H-alpha, H-beta, and [O III]. About 1200
flux measurements from 96 objects have been collected from the literature, from
unpublished observations, from the HST archive, or from new narrow-band filter
imaging. For most objects, the distance and reddening is known (or newly
determined), and luminosities were calculated from the observed fluxes. The
luminosity data were combined in five groups, according to nova light curve
type (very fast, fast, moderately fast, slow, recurrent); some objects were
re-assigned to other groups for a better fit of the luminosity data to the
general trend. For very fast, fast and moderately fast novae, the slope of the
[O III] decline is very similar, leading to a basic `switchoff' of [O III]
emission after 11, 23 and 24 years, respectively. For the same speed classes,
the slope of the Balmer luminosity is quite similar. In contrast to all types
of fast novae, the decline in Balmer luminosity is more rapid in slow novae.
However, the slope in [O III] is more gentle; slow novae still show [O III]
emission after 100 years. Thus shells of slow novae are still hot after one
century; the same applies for the shells of the very fast nova GK Per and the
recurrent nova T Pyx, which interact with circumstellar material.In recurrent
novae, [O III] is usually inconspicuous or absent. In objects with giant
companions, the Balmer luminosity decreases very slowly after an outburst,
which may be an effect of line blending of material from the ejecta and the
giant wind. On the other hand, objects with dwarf companions show a very rapid
decline in Balmer luminosity.


title:
The Limiting Stellar Initial Mass for Black Hole Formation in Close
  Binary Systems

abstract:
  We present models for the complete life and death of a 60 solar mass star
evolving in a close binary system, from the main sequence phase to the
formation of a compact remnant and fallback of supernova debris. After core
hydrogen exhaustion, the star expands, loses most of its envelope by Roche lobe
overflow, and becomes a Wolf-Rayet star. We study its post-mass transfer
evolution as a function of the Wolf-Rayet wind mass loss rate (which is
currently not well constrained and will probably vary with initial metallicity
of the star). Varying this mass loss rate by a factor 6 leads to stellar masses
at collapse that range from 3.1 to 10.7 solar masses. Although the iron core
masses at collapse are generally larger for stars with larger final masses,
they do not depend monotonically on the final stellar mass or even the C/O-core
mass. We then compute the evolution of all models through collapse and bounce.
The results range from strong supernova explosions for the lower final masses
to the direct collapse of the star into a black hole for the largest final
mass. Correspondingly, the final remnant masses, which were computed by
following the supernova evolution and fallback of material for a time scale of
about one year, are between 1.2 and 10 solar masses. We discuss the remaining
uncertainties of this result and outline the consequences of our results for
the understanding of the progenitor evolution of X-ray binaries and gamma-ray
burst models.


title: Conference Summary

abstract:
  Concluding remarks at the international workshop ``Tracing Cosmic Evolution
with Galaxy Clusters", held at Sesto Pusteria, Italy, July 3-6, 2001.


title:
The New Mexico alpha-omega Dynamo Experiment: Modeling Astrophysical
  Dynamos

abstract:
  A magnetic dynamo experiment is under construction at the New Mexico
Institute of Mining and Technology. The experiment is designed to demonstrate
in the laboratory the alpha-omega magnetic dynamo, which is believed to operate
in many rotating and conducting astrophysical objects. The experiment uses the
Couette flow of liquid sodium between two cylinders rotating with different
angular velocities to model the omega-effect. The alpha-effect is created by
the rising and expanding jets of liquid sodium driven through a pair of
orifices in the end plates of the cylindrical vessel, presumably simulating
plumes driven by buoyancy in astrophysical objects. The water analog of the
dynamo device has been constructed and the flow necessary for the dynamo has
been demonstrated. Results of the numerical simulations of the kinematic dynamo
are presented. The toroidal field produced by the omega-effect is predicted to
be B_{\phi} \simeq (R_m/2\pi) B_{poloidal}\simeq 20 \times B_{poloidal} for the
expected magnetic Reynolds number of R_m \sim 120. The critical rate of jets
necessary for the dynamo self-excitation is predicted from the calculations to
be a pair of plumes every 4 revolutions of the outer cylinder. For reasonable
technical limitations on the strength of materials and the power of the drive,
the self-excitation of the dynamo appears to be feasible.


title:
Detection of negative superhumps in a LMXRB -- an end to the long debate
  on the nature of V1405 Aql (X1916-053)

abstract:
  The detection of two similar periodicities (3001 and 3028 s) in the light
curve of V1405 Aql, a low mass X-ray Binary (LMXRB), has attracted the
attention of many observers. Two basic competing models have been offered for
this system. According to the first, V1405 Aql is a triple system. The second
model invokes the presence of an accretion disc that precesses in the apsidal
plane, suggesting that the shorter period is the orbital period while the
longer is a positive superhump. The debate on the nature of V1405 Aql has been
continued until very recently. Re-examination of previously published X-ray
data reveals an additional periodicity of 2979 s, which is naturally
interpreted as a negative superhump. The recently found 4.8-d period is
consequently understood as the nodal precession of the disc. This is the first
firm detection of negative superhumps and nodal precession in a LMXRB. Our
results thus confirm the classification of V1405 Aql as a permanent superhump
system. The 14-year argument on the nature of this intriguing object has thus
finally come to an end. We find that the ratio between the negative superhump
deficit (over the orbital period) and the positive superhump excess is a
function of orbital period in systems that show both types of superhumps. This
relation presents some challenge to theory as it fits binaries with different
components. We propose that a thickening in the disc rim, which causes
increased occultation of the X-ray source, is the mechanism responsible for
both types of superhumps in LMXRBs. According to our model superhumps (both in
the X-ray and optical regimes) are permitted in high inclination LMXRBs
contrary to Haswell et al. (2001) prediction.


title:
On the Maximal Quantity of Processed Information in the Physical
  Eschatological Context

abstract:
  An estimate of the maximal informational content available to advanced
extraterrestrial or future (post)human civilizations is presented. It is shown
that the fundamental thermodynamical considerations may lead to a quantitative
estimate of the largest quantity of information to be processed by conceivable
computing devices. This issue is interesting from the point of view of physical
eschatology, as well as general futurological topics, like the degree of
confidence in long-term physical predictions or viability of the large-scale
simulations of complex systems.


title: X-ray Radiation from the Millisecond Pulsar J0437-4715

abstract:
  We report on spectral and timing observations of the nearest millisecond
pulsar J0437-4715 with Chandra. The pulsar spectrum, detected up to 7 keV,
cannot be described by a simple one-component model. We suggest that it
consists of two components, a nonthermal power-law spectrum generated in the
pulsar magnetosphere, with a photon index about 2, and a thermal spectrum
emitted by heated polar caps, with a temperature decreasing outwards from 2 MK
to 0.5 MK. The lack of spectral features in the thermal component suggests that
the neutron star surface is covered by a hydrogen (or helium) atmosphere. The
timing analysis shows one X-ray pulse per period, with a pulsed fraction of
about 40% and the peak at the same pulse phase as the radio peak. No
synchrotron pulsar-wind nebula is seen in the X-rays.


title: Correlated X-ray timing and spectral behavior of GX 349+2: RXTE PCA data

abstract:
  We present a detailed and systematic investigation of correlated spectral and
timing properties of the Z source GX 349+2, using a huge amount (about 40 ks)
of good quality data from September 29, 1998 to October 13, 1998, obtained with
the Proportional-Counter-Array on-board RXTE satellite. We, for the first time,
give a detailed comparison between the normal-branch-properties and the
flaring-branch-properties of this source, as it shows an extended normal branch
(which is a rare phenomenon for it) for our case. In our work, the properties
of the peaked noise are analyzed as functions of the position on the Z-track
(in color-color-diagram), and they are discussed in connection with the peaked
noise seen for another Z source Cyg X-2 (at low overall intensities). This will
help to construct theoretical models for the peaked noise, as well as to
understand the physics behind the Z-shaped tracks traced by these kind of
sources in color-color-diagram. We also find a QPO (centroid frequency is about
3.8 Hz) at the upper part of the flaring branch. This is for the first time, a
QPO is seen from this source and hence is very important in understanding the
nature of its X-ray emitting components.


title: 557 GHz Observations of Water Vapor Outflows from VY CMa and W Hydrae

abstract:
  We report the first detection of thermal water vapor emission in the 557 GHz,
$1_{10} - 1_{01}$ ground state transition of ortho-H$_2$O toward VY Canis
Majoris. In observations obtained with the Submillimeter Wave Astronomy
Satellite (SWAS), we measured a flux of $\sim 450 $Jy, in a spectrally resolved
line centered on a velocity $v_{LSR} = 25 $km s$^{-1}$ with a full width half
maximum of $\sim 35$ km s$^{-1}$, somewhat dependent on the assumed line shape.
We analyze the line shape in the context of three different radial outflow
models for which we provide analytical expressions. We also detected a weaker
557 GHz emission line from W Hydrae. We find that these and other H$_2$O
emission line strengths scale as suggested by Zubko and Elitzur (2000).


title: Formation and Evolution of Galaxies in Clusters

abstract:
  Elliptical and S0 galaxies dominate the galaxy population in nearby rich
clusters such as Coma. Studies of the evolution of the colors, M/L ratios, and
line indices of early-type galaxies indicate that they have been a highly
homogeneous, slowly evolving population over the last ~65% of the age of the
Universe. On the other hand, recent evidence suggests that many early-type
galaxies in clusters have been transformed from spiral galaxies since z~1.
Arguably the most spectacular evidence for such transformations is the
incidence of red merger systems in several high redshift clusters. Due to this
morphological evolution the sample of early-type galaxies at high redshift is
only a subsample of the sample of early-type galaxies at low redshift. This
``progenitor bias'' results in an overestimate of the mean formation redshift
if simple models without morphological transformations are used. Models which
incorporate morphological evolution explicitly can bring the homogeneity, slow
evolution, and morphological transformations into agreement. The modeling shows
that the corrected mean formation redshift of the stars in early-type galaxies
may be as low as z~2 in a Lambda dominated Universe.


title:
Profiles of the Resonance Doublets Formed in Bipolar Winds in Symbiotic
  Stars

abstract:
  We compute the profiles of resonance doublet lines formed in bipolar winds
with velocity greater than the doublet separation in symbiotic stars.
Particular attention has been paid on the doublet line ratio, where the
conversion of the short wavelength component arising from the
$2S_{1/2}-2P_{3/2}$ transition into the long wavelengh component for the
transition $2S_{1/2}-2P_{1/2}$ plays an essential role in determining the flux
line ratio of the doublet. We adopted a Monte Carlo technique and the Sobolev
approximation. Our bipolar winds take the form of a cone and are characterised
by the terminal wind velocity, mass loss rate and the opening angle of the
cone. When the observer is in the polar direction and the Sobolev optical depth
is moderate $\tau_{Sob}\simeq 1$, then we mainly obtain profiles with inverted
flux line ratios, where the short wavelength component is weaker than the long
wavelength component. When the observer is in the equatorial direction, we find
that the profiles are characterised by two broad components, where the long
wavelength component is the broader and stronger of the two. We conclude that
the profiles obtained in our model provide qualitative understanding of broad
and inverted intensity ratio of the doublets in symbiotic stars and that the
bipolarity of the stellar winds can be inferred from the broader and stronger
long wavelength components in the doublet.


title:
Gravitational lensing as a possible explanation for some unidentified
  gamma-ray sources at high latitudes

abstract:
  We propose that some of the high-latitude unidentified EGRET gamma-ray
sources could be the result of gravitational lensing amplification of the
innermost regions of distant, faint, active galactic nuclei. These objects have
gamma-ray emitting regions small enough as to be affected by microlensing of
stars in interposed galaxies. We compute the gravitational amplification taking
into account effects of the host galaxy of the lens and prove that, whereas the
innermost gamma-ray regions can be magnified up to thousand times, there is no
amplification at radio frequencies, leading to the observed absence of strong
counterparts. Some new effects in the spectral evolution of a gravitational
microlensed gamma-ray AGN are predicted. Within a reasonable range of lensing
parameters, and/or types of sources, both variable and non-variable EGRET
detections at high latitudes can be explained by microlensing. The same
phenomenon could also have an important incidence among the future GLAST
detections at high-latitudes.


title:
Experimental Searches for Non-Baryonic Dark Matter: WIMP Direct
  Detection

abstract:
  An overview of the current status of WIMP direct searches is presented,
emphasizing strategies, achievements and prospects.


title:
Large-Scale Structure of the Universe and Cosmological Perturbation
  Theory

abstract:
  We review the formalism and applications of non-linear perturbation theory
(PT) to understanding the large-scale structure of the Universe. We first
discuss the dynamics of gravitational instability, from the linear to the
non-linear regime. This includes Eulerian and Lagrangian PT, non-linear
approximations, and a brief description of numerical simulation techniques. We
then cover the basic statistical tools used in cosmology to describe cosmic
fields, such as correlations functions in real and Fourier space, probability
distribution functions, cumulants and generating functions. In subsequent
sections we review the use of PT to make quantitative predictions about these
statistics according to initial conditions, including effects of possible non
Gaussianity of the primordial fields. Results are illustrated by detailed
comparisons of PT predictions with numerical simulations. The last sections
deal with applications to observations. First we review in detail practical
estimators of statistics in galaxy catalogs and related errors, including
traditional approaches and more recent developments. Then, we consider the
effects of the bias between the galaxy distribution and the matter
distribution, the treatment of redshift distortions in three-dimensional
surveys and of projection effects in angular catalogs, and some applications to
weak gravitational lensing. We finally review the current observational
situation regarding statistics in galaxy catalogs and what the future
generation of galaxy surveys promises to deliver.


title: Kinematics of Distant Galaxies from Keck

abstract:
  DEEP is a two-phase spectral survey of faint field galaxies with the Keck
Telescopes. The goals include exploring galaxy formation and evolution, mapping
distant large scale structures, and constraining cosmology. DEEP, since its
inception in the early 1990's, has been distinguished by an emphasis on
studying the kinematics and masses of distant galaxies. The major DEEP survey
in the second phase (DEEP2) is scheduled to begin in 2002 using a new
spectrograph and will mainly aim for a sample of 50,000 galaxies to I ~ 23.
Until then, the first phase of DEEP science programs will have been
concentrating on using existing Keck spectrographs to undertake spectral
surveys of over 1000 galaxies that have also been observed with HST. I will
highlight the study of rotation curves of distant spirals; the fundamental
plane of faint, high-redshift E/S0s; the narrow velocity widths seen in
luminous blue compact galaxies; and the diversity of kinematics seen in a small
sample of high redshift (z ~ 3) galaxies. These DEEP pilot programs have
clearly demonstrated the feasibility, importance, and potential of using
kinematics to better understand distant galaxies.


title: Properties of Cosmic Ray Interactions at PeV Energies

abstract:
  An analysis has been made of the present situation with the high energy
hadron-nucleus and nucleus-nucleus interaction models. As is already known
there are inconsistencies in the interpretation of experimental data on the
primary mass composition, which appear when different EAS components are used
for the analyses, even for the same experiment. In the absence of obvious
experimental defects, there is a clear need for an improvement to the existing
models; we argue that the most promising way is to introduce two effects which
should be present in nucleus-nucleus collisions and have not been allowed for
before. These are: a few percent energy transfer into the EAS electromagnetic
component due to electron-positron pair production or electromagnetic radiation
of quark-gluon plasma and a small slow-down of the cascading process in its
initial stages associated with the extended lifetime of excited nuclear
fragments. The latter process displaces the shower maximum deeper into the
atmosphere.


title:
Tales within Tales and Cutoffs within Cutoffs: What Sets the Mass Scale
  for Galaxies?

abstract:
  Please answer ``yes'' or ``no'': 1. Does the mass function for clusters of
galaxies cut off exponentially? 2. Does the luminosity function for galaxies
cut off exponentially? 3. Is the dependence of virial velocity on galaxy
luminosity a power law? 4. Does the velocity function for galaxies cut off
exponentially?


title: Structure and Physical Conditions in MHD Jets from Young Stars

abstract:
  We have constructed the foundations to a series of theoretical diagnostic
methods to probe the jet phenomenon in young stars as observed at various
optical forbidden lines. We calculate and model in a self-consistent manner the
physical and radiative processes which arise within an inner disk-wind driven
magnetocentrifugally from the circumstellar accretion disk of a young sun-like
star. Comparing with real data taken at high angular resolution, our approach
will provide the basis of systematic diagnostics for jets and their related
young stellar objects, to attest the emission mechanisms of such phenomena.
This work can help bring first-principle theoretical predictions to confront
actual multi-wavelength observations, and will bridge the link between many
very sophiscated numerical simulations and observational data. Analysis methods
discussed here are immediately applicable to new high-resolution data obtained
with HST and Adaptic Optics.


title: An Empirical Calibration of Star Formation Rate Estimators

abstract:
  (Abridged) The observational determination of the behaviour of the star
formation rate (SFR) with look-back time or redshift has two main weaknesses:
1- the large uncertainty of the dust/extinction corrections, and 2- that
systematic errors may be introduced by the fact that the SFR is estimated using
different methods at different redshifts. To assess the possible systematic
differences among the different SFR estimators and the role of dust, we have
compared SFR estimates using H$\alpha$, SFR(H$\alpha$), [OII]$\lambda$3727\AA,
SFR(OII), UV, SFR(UV) and FIR, SFR(FIR) luminosities of a sample comprising the
31 nearby star forming galaxies having high quality photometric data in the UV,
optical and FIR.
  We review the different "standard" methods for the estimation of the SFR and
find that while the standard method provides good agreement between
SFR(H$\alpha$) and SFR(FIR), both SFR(OII) and SFR(UV) are systematically
higher than SFR(FIR), irrespective of the extinction law.
  We show that the excess in the SFR(OII) and SFR(UV) is mainly due to an
overestimate of the extinction resulting from the effect of underlying stellar
Balmer absorptions in the measured emission line fluxes. Taking this effect
into consideration in the determination of the extinction brings the SFR(OII)
and SFR(UV) in line with the SFR(FIR) and simultaneously reduces the internal
scatter of the SFR estimations. Based on these results we have derived
"unbiased" SFR expressions for the SFR(UV), SFR(OII) and SFR(H$\alpha$). We
have used these estimators to recompute the SFR history of the Universe using
the results of published surveys.


title: On the secondary star of the cataclysmic variable 1RXS J094432.1+035738

abstract:
  We present V and Rc band photometry and optical near-infrared spectroscopy of
the cataclysmic variable 1RXS J094432.1+035738. We detected features of a cool
secondary star, which can be modeled with a red dwarf of spectral type M2 (+0.5
-1.0) V at a distance of 433 +- 100 pc.


title: Broad-band Modeling of GRB Afterglows

abstract:
  Observations of GRB afterglows ranging from radio to X-ray frequencies
generate large data sets. Careful analysis of these broad-band data can give us
insight into the nature of the GRB progenitor population by yielding such
information like the total energy of the burst, the geometry of the fireball
and the type of environment into which the GRB explodes. We illustrate, by
example, how global, self-consistent fits are a robust approach for
characterizing the afterglow emission. This approach allows a relatively simple
comparison of different models and a way to determine the strengths and
weaknesses of these models, since all are treated self-consistently. Here we
quantify the main differences between the broad-band, self-consistent approach
and the traditional approach, using GRB000301C and GRB970508 as test cases.


title: Radio, Sub-mm, and X-ray Studies of Gamma-Ray Burst Host Galaxies

abstract:
  The study of gamma-ray burst (GRB) host galaxies in the radio, sub-mm, and
X-ray wavelength regimes began only recently, in contrast to optical studies.
This is mainly due to the long timescale on which the radio afterglow emission
decays, and to the intrinsic faintness of radio emission from star-forming
galaxies at z~1, as well as source confusion in sub-mm observations; X-ray
observations of GRB hosts have simply not been attempted yet. Despite these
difficulties, we have recently made the first detections of radio and sub-mm
emission from the host galaxies of GRB980703 and GRB010222, respectively, using
the VLA and the SCUBA instrument on JCMT. In both cases we find that the
inferred star formation rates (~500 solar masses per year) and bolometric
luminosities (~few 10^12 solar luminosities) indicate that these galaxies are
possibly analogous to the local population of Ultra-Luminous Infrared Galaxies
(ULIRGs) undergoing a starburst. However, there is a modest probability that
the observed emission is due to AGN activity rather than star formation, thus
requiring observations with Chandra or XMM. The sample of GRB hosts offers a
number of unique advantages to the broader question of the evolution of
galaxies and star formation from high redshift to the present time since: (i)
GRBs trace massive stars, (ii) are detectable to high redshifts, and (iii) have
immense dust penetrating power. Therefore, radio/sub-mm/X-ray observations of
GRB hosts can potentially provide crucial information both on the nature of the
GRB host galaxies, and on the history of star formation.


title: Gravitational wave amplification of seed magnetic fields

abstract:
  We discuss how gravitational waves could amplify seed magnetic fields to
strengths capable of supporting the galactic dynamo. We consider the
interaction of a weak magnetic field with gravity wave distortions in almost
FRW cosmologies and find that the magnitude of the original field is amplified
proportionally to the wave induced shear anisotropy and, crucially,
proportionally to the square of the field's initial scale. The latter makes our
mechanism particularly efficient when operating on superhorizon sized magnetic
fields, like those produced during inflation. In that case, the achieved
amplification can easily boost magnetic strengths, which may still lie
relatively close to the galactic dynamo lower limits, well within the currently
accepted range.


title:
Dynamical evolution of clusters of galaxies: the effect of high-
  velocity substructure clumps

abstract:
  In the Cold Dark Matter (hereafter CDM) scenario even isolated density peaks
contain a high fraction of small scale clumps having velocities larger than the
average escape velocity from the structure. These clumps populate
protoclusters, especially in the peripheral regions, r > R_f (where R_f is the
filtering scale). During the cluster collapse and the subsequent secondary
infall, collapsing or infalling clumps (having v<v_esc) interact with the
quoted unbound clumps (or high speed clumps, as we also call them) having v >
v_esc. We study the interaction between these two kind of clumps by means of
the impulse approximation and we find that the collapse of bound clumps is
accelerated with respect to the homogeneous case (Gunn & Gott's model). The
acceleration of the collapse increases with decreasing height of the peak, \nu.
We finally compare the acceleration produced by this effect to the slowing down
effect produced by the gravitational interaction of the quadrupole moment of
the system with the tidal field of the matter of the neighboring proto-clusters
studied in Del Popolo & Gambera. We find that the magnitude of the slowing down
effect is larger than the acceleration produced by the effect studied in this
paper, only in the outskirts of the cluster. We want to stress that the one
which we study in this paper is also present in an isolated protocluster, being
produced by the interaction of the collapsing clumps with the unbound
substructure internal to the collapsing clumps itself while that studied in Del
Popolo & Gambera (1998) is produced by substructure external to the density
peak.


title:
Detection of a high frequency break in the X-ray power spectrum of Ark
  564

abstract:
  We present a power spectrum analysis of the long ASCA observation of Ark 564
in June/July 2001. The observed power spectrum covers a frequency range of ~
3.5 decades. We detect a high frequency break at ~ 0.002 Hz. The power spectrum
has an rms of ~30% and a slope of ~ -1 and ~ -2 below and above the break
frequency. When combined with the results from a long RXTE observation (Pounds
et al. 2001), the observed power spectra of Ark 564 and Cyg X-1 (in the
low/hard state) are almost identical, showing a similar shape and rms
amplitude. However, the ratio of the high frequency breaks is very small (~
10e{3-4}), implying that these characteristic frequencies are not indicative of
the black hole mass. This result supports the idea of a small black hole
mass/high accretion rate in Ark 564.


title:
Tolman-Bondi collapse in scalar-tensor theories as a probe of
  gravitational memory

abstract:
  In cosmological models with a varying gravitational constant, it is not clear
whether primordial black holes preserve the value of $G$ at their formation
epoch. We investigate this question by using the Tolman-Bondi model to study
the evolution of a background scalar field when a black hole forms from the
collapse of dust in a flat Friedmann universe. Providing the back reaction of
the scalar field on the metric can be neglected, we find that the value of the
scalar field at the event horizon very quickly assumes the background
cosmological value. This suggests that there is very little gravitational
memory.


title: Stationary state in N-body System with power law interaction

abstract:
  Many self-gravitating systems often show scaling properties in their mass
density, system size, velocities and so on. In order to clarify the origin of
these scaling properties, we consider the stationary state of N-body system
with inverse power law interaction. As a simple case, we consider the
self-similar stationary solution in the collisionless Boltzmann equation with
power law potential and investigate its stability in terms of a linear
symplectic perturbation. The stable scaling solutions obtained are
characterized by the power index of the potential and the virial ratio of the
initial state. It is suggested in general that the nonextensive system has much
various stable scaling solutions than those in the extensive system.


title: Accelerating Universe from the Evolution of Extra Dimensions

abstract:
  In this paper we propose that the accelerating expansion of the present
matter-dominated universe, as suggested by the recent distance measurements of
type Ia supernovae, is generated along with the evolution of space in extra
dimensions. The Einstein equations are first analyzed qualitatively and then
solved numerically, so as to exhibit explicitly these patterns of the
accelerating expansion in this scenario. A fine-tuning problem associated with
such a scenario is also described and discussed.


title: The Impact of Cooling and Feedback on Disc Galaxies

abstract:
  We present detailed, analytical models for the formation of disc galaxies to
investigate the impact that cooling and feedback have on their structural
properties. In particular, we investigate which observables extracted directly
from the models are best suited as virial mass estimators, and to what extent
they allow the recovery of the model input parameters regarding the feedback
and cooling efficiencies. Contrary to naive expectations, the luminosities and
circular velocities of disc galaxies are extremely poor indicators of total
virial mass. Instead, we show that the product of disc scale length and
rotation velocity squared yields a much more robust estimate. We show that
feedback can cause a narrow correlation between galaxy mass fraction and halo
spin parameter, similar to that found recently by van den Bosch, Burkert and
Swaters from an analysis of dwarf galaxy rotation curves. Finally we
investigate the impact that cooling and feedback have on the colors,
metallicities, star formation histories and Tully-Fisher relation of disc
galaxies.


title:
First XMM-Newton observations of strongly magnetic cataclysmic variables
  - II. Timing studies of DP Leo and WW Hor

abstract:
  XMM-Newton was used to observe two eclipsing, magnetic cataclysmic variables,
DP Leo and WW Hor, continuously for three orbital cycles each. Both systems
were in an intermediate state of accretion. For WW Hor we also obtained optical
light curves with the XMM-Newton Optical Monitor and from ground-based
observations. Our analysis of the X-ray and optical light curves allows us to
constrain physical and geometrical parameters of the accretion regions and
derive orbital parameters and eclipse ephemerides of the systems. For WW Hor we
directly measure horizontal and vertical temperature variations in the
accretion column. From comparisons with previous observations we find that
changes in the accretion spot longitude are correlated with the accretion rate.
For DP Leo the shape of the hard X-ray light curve is not as expected for
optically thin emission, showing the importance of optical depth effects in the
post-shock region. We find that the spin period of the white dwarf is slightly
shorter than the orbital period and that the orbital period is decreasing
faster than expected for energy loss by gravitational radiation alone.


title: An AGN Identification for 3EG J2006-2321

abstract:
  We present a multiwavelength analysis of the high-energy gamma-ray source 3EG
J2006-2321. The flux of this source above 100 MeV is shown to be variable on
time scales of days and months. Optical observations and careful examination of
archived radio data indicate that its radio counterpart is PMN J2005-2310, a
flat-spectrum radio quasar with a 5-GHz flux density of 260 mJy. Study of the
$V=18.7$ optical counterpart indicates a redshift of 0.833 and variable linear
polarization. No X-ray source has been detected near the position of PMN
J2005-2310, but an X-ray upper limit is derived from ROSAT data. This upper
limit provides for a spectral energy distribution with global characteristics
similar to those of known gamma-ray blazars. Taken together, these data
indicate that 3EG J2006-2321, listed as unidentified in the 3rd EGRET Catalog,
is a member of the blazar class of AGN. The 5-GHz radio flux density of this
blazar is the lowest of the 68 EGRET-detected AGN. The fact that EGRET has
detected such a source has implications for unidentified EGRET sources,
particularly those at high latitudes ($|b|>30^{\circ}$), many of which may be
blazars.


title:
Time-Dependent, Multifluid, Magnetohydrodynamic Shock Waves with Grain
  Dynamics I. Formulation and Numerical Tests

abstract:
  This is the first in a series of papers on the effects of dust on the
formation, propagation, and structure of nonlinear MHD waves and MHD shocks in
weakly-ionized plasmas. We model the plasma as a system of 9 interacting
fluids, consisting of the neutral gas, ions, electrons, and 6 grain fluids
comprised of very small grains or PAHs and classical grains in different charge
states. We formulate the governing equations for perpendicular shocks under
approximations appropriate for dense molecular clouds, protostellar cores, and
protoplanetary disks. We describe a code that obtains numerical solutions using
a finite difference method, and estabish its accuracy by comparing numerical
and exact solutions for special cases.


title: Spheroidal Galaxies/QSOs Connection

abstract:
  In view of the extensive evidence of a tight inter-relationship between
spheroidal galaxies (and galactic bulges) and massive black holes hosted at
their centers, a consistent model must deal jointly with the evolution of the
two components. We describe one viable model, which successfully accounts for
the local luminosity function of spheroidal galaxies, their photometric and
chemical properties, deep galaxy counts in different wavebands, including those
in the (sub)-mm region which proved to be critical for current semi-analytic
models stemming from the standard hierarchical clustering picture, clustering
properties of SCUBA galaxies, of EROs, and of LBGs, as well as for the local
mass function of massive black holes and for quasar evolution. Predictions that
can be tested by surveys carried out by SIRTF are presented.


title:
Quasiequilibrium sequences of synchronously rotating binary neutron
  stars with constant rest masses in general relativity -- Another approach
  without using the conformally flat condition --

abstract:
  We have computed quasiequilibrium sequences of synchronously rotating compact
binary star systems with constant rest masses. This computation has been
carried out by using the numerical scheme which is different from the scheme
based on the conformally flat assumption about the space. Stars are assumed to
be polytropes with polytropic indices of N=0.5, N=1.0, and N=1.5. Since we have
computed binary star sequences with a constant rest mass, they provide
approximate evolutionary tracks of binary star systems. For relatively stiff
equations of state (N < 1.0), there appear turning points along the
quasiequilibrium sequences plotted in the angular momentum -- angular velocity
plane. Consequently secular instability against exciting internal motion sets
in at those points. Qualitatively, these results agree with those of Baumgarte
et al. who employed the conformally flat condition. We further discuss the
effect of different equations of state and different strength of gravity by
introducing two kinds of dimensionless quantities which represent the angular
momentum and the angular velocity. Strength of gravity is renormalized in these
quantities so that the quantities are transformed to values around unity.
Therefore we can clearly see relations among quasiequilibrium sequences for a
wide variety of strength of gravity and for different compressibility.


title: Selfgravity and QSO disks

abstract:
  It is well known that the outer parts of QSO accretion disks are prone to
selfgravity if heated solely by orbital dissipation. Such disks might be
expected to form stars rather than accrete onto the black hole. The arguments
leading to this conclusion are reviewed. Conversion of a part of the gas into
high-mass stars or stellar-mass black holes, and the release of energy in these
objects by fusion or accretion, may help to stabilize the remaining gas. If the
disk extends beyond a parsec, however, more energy is probably required for
stability than is available by turning half the gas into high-mass stars. Small
black holes are perhaps marginally viable energy sources, with important
implications (not pursued here) for the QSO spectral energy distribution, the
metallicity of the gas, microlensing of QSO disks, and perhaps
gravitational-wave searches. Other possible palliatives for selfgravity include
accretion driven by nonviscous torques that allow near-sonic accretion speeds
and hence lower surface densities for a given mass accretion rate. All such
modes of accretion face major theoretical difficulties, and in any case merely
postpone selfgravity. Alternatively, thin disks may not exist beyond a thousand
Schwarzshild radii or so (0.01 parsec), in which case QSOs must be fueled by
gas with small specific angular momentum.


title: Synergistic warm inflation

abstract:
  We consider an alternative warm inflationary scenario in which $n$ scalar
fields coupled to a dissipative matter fluid cooperate to produce power--law
inflation. The scalar fields are driven by an exponential potential and the
bulk dissipative pressure coefficient is linear in the expansion rate. We find
that the entropy of the fluid attains its asymptotic value in a characteristic
time proportional to the square of the number of fields. This scenario remains
nearly isothermal along the inflationary stage. The perturbations in energy
density and entropy are studied in the long--wavelength regime and seen to grow
roughly as the square of the scale factor. They are shown to be compatible with
COBE measurements of the fluctuations in temperature of the CMB.


title: The Observational Case for Jupiter Being a Typical Massive Planet

abstract:
  We identify a subsample of the recently detected extrasolar planets that is
minimally affected by the selection effects of the Doppler detection method.
With a simple analysis we quantify trends in the surface density of this
subsample in the period - Msin(i) plane. A modest extrapolation of these trends
puts Jupiter in the most densely occupied region of this parameter space, thus
indicating that Jupiter is a typical massive planet rather than an outlier. Our
analysis suggests that Jupiter is more typical than indicated by previous
analyses. For example, instead of M_Jup mass exoplanets being twice as common
as 2 M_Jup exoplanets, we find they are three times as common.


title:
Centimeter searches for molecular line emission from high-redshift
  galaxies

abstract:
  We consider the capabilities for detecting low order CO emission lines from
high-z galaxies using the next generation of radio telescopes operating at 22
and 43 GHz. We employ models for the evolution of dusty star forming galaxies
based on source counts at (sub)millimeter wavelengths, and on the observed mm
through infrared backgrounds, to predict the expected detection rate of
low-order CO(2-1) and CO(1-0) line emitting galaxies for optimal
centimeter(cm)-wave surveys using future radio telescopes, such as the Square
Kilometer Array (SKA) and the Expanded Very Large Array (EVLA). We then compare
these results to surveys that can be done with the next-generation mm-wave
telescope, the Atacama Large Millimeter Array (ALMA). Operating at 22 GHz the
SKA will be competitive with the ALMA in terms of the detection rate of lines
from high-z galaxies, and will be potentially superior by an order of magnitude
if extended to 43 GHz. Perhaps more importantly, cm-wave telescopes are
sensitive to lower excitation gas in higher redshift galaxies, and so provide a
complementary view of conditions in high redshift galaxies to mm-wave surveys.
We have also included in our models emission from HCN. The number of HCN(1-0)
detections will be about 5% of the CO detections in the (CO-optimized) 22 GHz
surveys, and about 1.5% for 43 GHz surveys. In order not to over-resolve the
sources, brightness temperature limitations require that a future large area cm
telescopes have much of its collecting area on baselines shorter than 10 km.


title:
High time resolution observations of the January 2000 glitch in the Vela
  pulsar

abstract:
  Pulsars are rotating neutron stars, sweeping the emission regions from the
magnetic poles across our line of sight. Isolated neutron stars lose angular
momentum through dipole radiation and (possibly) particle winds, hence they
slow down extremely steadily, making them amongst the most reliable timing
sources available. However, it is well known that younger pulsars can suffer
glitches, when they suddenly deviate from their stable rotation period. On 2000
January 16 (MJD 51559) the rate of pulsation from the Vela pulsar (B0833-45)
showed such a fractional period change of {\rm $3.1\times 10^{-6}$}, the
largest recorded for this pulsar. The glitch was detected and reported by the
Hobart radio telescope. The speedy announcement allowed the X-ray telescope,
Chandra, and others, to make Target of Opportunity observations. The data
placed an upper limit of 40 seconds for the transition time from the original
to the new period. Four relaxation timescales are found, which are believed to
be due to the variable coupling between the crust and the interior fluid. One
is very short, about 60 seconds; the others have been previously reported and
are 0.56, 3.33 and 19.1 days in length.


title: Measuring the Virial Masses of Disk Galaxies

abstract:
  I present detailed models for the formation of disk galaxies, and investigate
which observables are best suited as virial mass estimators. Contrary to naive
expectations, the luminosities and circular velocities of disk galaxies are
extremely poor indicators of total virial mass. Instead, I show that the
product of disk scale length and rotation velocity squared yields a much more
robust estimate. Finally, I show how this estimator may be used to put limits
on the efficiencies of cooling and feedback during the process of galaxy
formation.


title:
Heat expansion of star-like cosmic objects induced by the cosmological
  expansion

abstract:
  The heat expansion of a star-like cosmic object, induced by the cosmological
bremsheat production within a moving body, that was predicted by the Projective
Unified field Theoriy of the author, is approximately treated. The difference
to planet-like bodies investigated previously arises from another material
constitution. The exponential-like expansion law is applied to a model with
numerical values of the Sun. The results are not in contradiction to empirical
facts.


title:
Identification of Galactic Wind Candidates using Excitation Maps:
  Tunable-Filter Discovery of a Shock-Excited Wind in the Galaxy NGC 1482

abstract:
  Multi-line imaging of the nearby disk galaxy NGC 1482 with the Taurus Tunable
Filter (TTF) on the Anglo-Australian Telescope reveals a remarkable
hourglass-shaped [N II] 6583/H-alpha excitation structure suggestive of a
galactic wind extending at least 1.5 kpc above and below the disk of the host
galaxy. Long-slit spectroscopy confirms the existence of a large-scale outflow
in this galaxy. The entrained wind material has [N II] 6583/H-alpha ratios in
excess of unity while the disk material is characterized by H II region-like
line ratios indicative of a starburst. Expansion velocities of order 250 km/s
are detected in the wind material, and a lower limit of 2 x 10^{53} ergs is
derived for the kinetic energy of the outflow based on the gas kinematics and
the amount of ionized material entrained in the outflow. This is the first time
to our knowledge that a galactic wind is discovered using excitation maps. This
line ratio technique represents a promising new way to identify wind galaxy
candidates before undergoing more time-consuming spectroscopic follow-ups. This
method of selection may be particularly useful for samples of galaxies at
moderate redshifts.


title: SiO chimneys and supershells in M82

abstract:
  In this Letter we present the first images of the emission of SiO and H13CO+
in the nucleus of the starburst galaxy M82. Contrary to other molecular species
that mainly trace the distribution of the star-forming molecular gas within the
disk, the SiO emission extends noticeably out of the galaxy plane. The bulk of
the SiO emission is restricted to two major features. The first feature,
referred to as the SiO supershell, is an open shell of 150 pc diameter, located
120 pc west from the galaxy center.
  The SiO supershell represents the inner front of a molecular shell expanding
at 40 km/s, produced by mass ejection around a supercluster of young stars
containing supernova remnant SNR 41.95+57.5. The second feature is a vertical
filament, referred to as the SiO chimney, emanating from the disk at 200 pc
east from the galaxy center. The SiO chimney reaches a 500 pc vertical height,
and it is associated with the most prominent chimney identified in radio
continuum maps. The kinematics, morphology, and fractional abundances of the
SiO gas features in M82 can be explained in the framework of shocked chemistry
driven by local episodes of gas ejection from the starburst disk.


title: Radial structure of galactic stellar disks

abstract:
  We present the results from our deep optical imaging survey \mu_lim=26-27
V-mag/arcsec^2 of a morphologically selected sample of 72 edge-on disk
galaxies. The question of the global structure of galactic stellar disks,
especially the radial surface brightness profile at large galactocentric
distances, is addressed. We find that typical radial profiles are better
described by a two-slope exponential profile --characterised by an inner and
outer scalelength separated at a break radius-- rather than a sharply-truncated
exponential model. Results are given for three face-on equivalents, serving as
the crucial test to assure the findings for the edge-on sample without possible
geometrical line-of-sight effects.


title:
Ultra Compact Objects in the Fornax Cluster of Galaxies: Globular
  clusters or dwarf galaxies?

abstract:
  The relation between the Ultra Compact Objects (UCOs) recently discovered in
the Fornax cluster (Drinkwater et al. 2000, Hilker et al. 1999) and the
brightest globular clusters associated with the central galaxy NGC 1399 has
been investigated. The question was adressed whether the UCOs constitute a
distinct population of objects not linked to globular clusters or whether there
is a smooth transition between both populations. Therefore, a spectroscopic
survey on compact objects in the central region of the Fornax cluster was
carried out with the 2.5m du Pont telescope (LCO). UCOs and the bright NGC 1399
globular clusters with similar brightness were inspected. 12 GCs from the
bright end of the globular cluster luminosity function have been identified as
Fornax members. Eight are new members, four were known as members from before.
Their magnitude distribution supports a smooth transition between the faint
UCOs and the bright globular clusters. There is no evidence for a magnitude gap
between both populations. However, the brightest UCO clearly stands out, it is
too bright and too large to be accounted for by globular clusters. For the only
UCO included in our survey, a relatively high metallicity of about [Fe/H]=-0.5
dex is measured.


title:
Measuring the properties of extragalactic dust and implications for the
  Hubble diagram

abstract:
  Scattering and absorption of light by a homogeneous distribution of
intergalactic large dust grains has been proposed as an alternative,
non-cosmological explanation for the faintness of Type Ia supernovae at $z\s im
0.5$. We investigate the differential extinction for high-redshift sources
caused by extragalactic dust along the line of sight.
  Future observations of Type Ia supernovae up to $z\sim 2$, e.g. by the
proposed SNAP satellite, will allow the measurement of the properties of dust
over cosmological distances. We show that 1% {\em relative} spectrophotometric
accuracy (or broadband photometry) in the wavelength interval 0.7--1.5 $\mu$m
is required to measure the extinction caused by ``grey'' dust down to $\delta
m=0.02$ magnitudes.
  We also argue that the presence of grey dust is not necessarily inconsistent
with the recent measurement of the brightness of a supernova at $z=1.7$ (SN
1997ff), in the absence of accurate spectrophotometric information of the
supernova.


title:
On the Optimization of Broad-Band Photometry for Galaxy Evolution
  Studies

abstract:
  We have derived the uncertainties to be expected in the derivation of galaxy
physical properties (star formation history, age, metallicity, reddening) when
comparing broad-band photometry to the predictions of evolutionary synthesis
models. We have obtained synthetic colors for a large sample (9000) of
artificial galaxies assuming different star formation histories, ages,
metallicities, reddening values, and redshifts. The colors derived have been
perturbed by adopting different observing errors, and compared back to the
evolutionary synthesis models grouped in different sets. The comparison has
been performed using a combination of Monte Carlo simulations, a Maximum
Likelihood Estimator and Principal Component Analysis. After comparing the
input and derived output values we have been able to compute the uncertainties
and covariant degeneracies between the galaxy physical properties as function
of (1) the set of observables available, (2) the observing errors, and (3) the
galaxy properties themselves. In this work we have considered different sets of
observables, some of them including the standard Johnson/Cousins (UBVRI) and
Sloan Digital Sky Survey (SDSS) bands in the optical, the 2 Micron All Sky
Survey (2MASS) bands in the near-infrared, and the Galaxy Evolution Explorer
(GALEX) bands in the UV, at three different redshifts, z=0.0, 0.7, and 1.4.
This study is intended to represent a basic tool for the design of future
projects on galaxy evolution, allowing an estimate of the optimal band-pass
combinations and signal-to-noise ratios required for a given scientific
objective.


title: Determination of stellar parameters with GAIA

abstract:
  The GAIA Galactic survey satellite will obtain photometry in 15 filters of
over 10^9 stars in our Galaxy across a very wide range of stellar types. No
other planned survey will provide so much photometric information on so many
stars. I examine the problem of how to determine fundamental physical
parameters (Teff, log g, [Fe/H] etc.) from these data. Given the size,
multidimensionality and diversity of this dataset, this is a challenging task
beyond any encountered so far in large-scale stellar parametrization. I
describe the problems faced (initial object identification, interstellar
extinction, multiplicity, missing data etc.) and present a framework in which
they can can be addressed. A probabilistic approach is advocated on the grounds
that it can take advantage of additional information (e.g. priors and data
uncertainties) in a consistent and useful manner, as well as give meaningful
results in the presence of poor or degenerate data. Furthermore, I suggest an
approach to parametrization which can use the other information GAIA will
acquire, in particular the parallax, which has not previously been available
for large-scale multidimensional parametrization. Several of the problems
identified and ideas suggested will be relevant to other large surveys, such as
SDSS, DIVA, FAME, VISTA and LSST, as well as stellar parametrization in a
virtual observatory.


title: When did the Large Elliptical Galaxies Form?

abstract:
  The simple reading of the evidence is that the large elliptical galaxies
existed at about the present star mass and comoving number density at redshift
z=2. This is subject to the usual uncertainties of measurement and
interpretation in astronomy, but should be taken seriously because it is
indicated by quite a few lines of evidence. And it might be a guide to a more
perfect theory of galaxy formation.


title: The Light Curve of S Andromedae

abstract:
  Historical observations of S And, in combination with the color versus
rate-of-decline relationship for well-observed SN 1991bg-like supernovae, are
used to estimate a rate of decline Delta m15 (B) = 2.21 and an intrinsic color
at maximum [B(0) - V(0)]o = 1.32 for SN 1885A.


title:
The stellar velocity dispersion of the lens galaxy in MG2016+112 at
  z=1.004

abstract:
  We present a direct measurement of the stellar velocity dispersion of the
early-type lens galaxy D in the system MG2016+112 (z=1.004), determined from a
spectrum obtained with the Echelle Spectrograph and Imager (ESI) on the W.M.
Keck-II Telescope, as part of the Lenses Structure and Dynamics (LSD) Survey.
We find a velocity dispersion of sigma_ap=304+-27 km/s inside an effective
circular aperture with a radius of 0.65'', corresponding to a central velocity
dispersion of sigma=328+-32 km/s. From a Hubble Space Telescope F160W-band
image, we measure the effective radius and effective surface brightness in
order to determine the offset of the lens galaxy with respect to the local
Fundamental Plane. The offset corresponds to an evolution of the rest-frame
effective mass-to-light ratio of Delta log(M/L_B)=-0.62+-0.08 from z=0 to
z=1.004. By interpreting colors and offset of the FP with two independent
stellar population synthesis models, we obtain a single-burst equivalent age of
2.8+-0.8 Gyr (i.e. z_f>1.9) and a supersolar metallicity of
log[Z/Z_sun]=0.25+-0.25. The lens galaxy is therefore a massive elliptical
dominated by an old and metal rich stellar population at z>1. The excellent
agreement of the stellar velocity dispersion with that predicted from recent
lens models confirms that the angular separation of the multiple images of the
background QSO is predominantly due to the lens galaxy, and not to a massive
``dark cluster'', in agreement with recent weak lensing and X-ray observations.
However, the significant overdensity of galaxies in the field might indicate
that this system is a proto-cluster, in formation around galaxy D, responsible
for the ~10% external shear inferred from the strong lens models.


title: Evidence for Nearby Supernova Explosions

abstract:
  Supernova explosions are one of the most energetic--and potentially
lethal--phenomena in the Universe. Scientists have speculated for decades about
the possible consequences for life on Earth of a nearby supernova, but
plausible candidates for such an event were lacking. Here we show that the
Scorpius-Centaurus OB association, a group of young stars currently located
at~130 parsecs from the Sun, has generated 20 SN explosions during the last 11
Myr, some of them probably as close as 40 pc to our planet. We find that the
deposition on Earth of 60Fe atoms produced by these explosions can explain the
recent measurements of an excess of this isotope in deep ocean crust samples.
We propose that ~2 Myr ago, one of the SNe exploded close enough to Earth to
seriously damage the ozone layer, provoking or contributing to the
Pliocene-Pleistocene boundary marine extinction.

categories: astro-ph nucl-ex physics.ao-ph physics.geo-ph


title:
A Coupled Dynamical and Chemical Model of Starless Cores of Magnetized
  Molecular Clouds: I. Formulation and Initial Results

abstract:
  We develop a detailed chemical model for the starless cores of strongly
magnetized molecular clouds, with the ambipolar diffusion-driven dynamic
evolution of the clouds coupled to the chemistry through ion abundances. We
concentrate on two representative model clouds in this initial study, one with
magnetic fields and the other without. The model predictions on the peak values
and spatial distributions of the column densities of CO, CCS, N$_2$H$^+$ and
HCO$^+$ are compared with those observationally inferred for the well-studied
starless core L1544, which is thought to be on the verge of star formation. We
find that the magnetic model, in which the cloud is magnetically supported for
several million years before collapsing dynamically, provides a reasonable
overall fit to the available data on L1544; the fit is significantly worse for
the non-magnetic model, in which the cloud collapses promptly. The observed
large peak column density for N$_2$H$^+$ and clear central depression for CCS
favor the magnetically-retarded collapse over the free-fall collapse. A
relatively high abundance of CCS is found in the magnetic model, resulting most
likely from an interplay of depletion and late-time hydrocarbon chemistry
enhanced by CO depletion. These initial results lend some support to the
standard picture of dense core formation in strongly magnetized clouds through
ambipolar diffusion. They are at variance with those of Aikawa et al. (2001)
who considered a set of models somewhat different from ours and preferred one
in which the cloud collapses more or less freely for L1544.


title: Holographic Discreteness of Inflationary Perturbations

abstract:
  The holographic entropy bound is used to estimate the quantum-gravitational
discreteness of inflationary perturbations. In the context of scalar inflaton
perturbations produced during standard slow-roll inflation, but assuming that
horizon-scale perturbations ``freeze out'' in discrete steps separated by one
bit of total observable entropy, it is shown that the Hilbert space of a
typical horizon-scale inflaton perturbation is equivalent to that of about 10^5
binary spins-- approximately the inverse of the final scalar metric
perturbation amplitude, independent of other parameters. Holography thus
suggests that in a broad class of fundamental theories, inflationary
perturbations carry a limited amount of information (about 10^5 bits per mode)
and should therefore display discreteness not predicted by the standard field
theory. Some manifestations of this discreteness may be observable in cosmic
background anisotropy.


title: Observing Quanta on a Cosmic Scale

abstract:
  Our entire galaxy, like all others, originated as a fairly smooth patch of
binding energy, which in turn originated as a single quantum perturbation of
the inflaton field on a subatomic scale during inflation. The best preserved
relic of these perturbations is the anisotropy of the microwave background
radiation, which on the largest scales preserves a faithful image of the
primordial quantum fields. It is possible that close study of these
perturbations might reveal signs of discreteness caused by spacetime
quantization.


title: Bifurcation for Dynamical Systems of Planet-Belt Interaction

abstract:
  The dynamical systems of planet-belt interaction are studied by the
fixed-point analysis and the bifurcation of solutions on the parameter space is
discussed. For most cases, our analytical and numerical results show that the
locations of fixed points are determined by the parameters and these fixed
points are either structurally stable or unstable. In addition to that, there
are two special fixed points: the one on the inner edge of the belt is
asymptotically stable and the one on the outer edge of the belt is unstable.
This is consistent with the observational picture of Asteroid Belt between the
Mars and Jupiter: the Mars is moving stablely close to the inner edge but the
Jupiter is quite far from the outer edge.


title:
An artificial meteors database as a test for the presence of weak
  showers

abstract:
  We have constructed an artificial meteor database resembling in all details
the real sample collected by the observers of the Comets and Meteors Workshop
in the years 1996-1999. The artificial database includes the sporadic meteors
and also events from the following showers: Perseids, Aquarid complex, Alpha
Capricornids, July Pegasids and Sagittarids. This database was searched for the
presence of the radiants of two weak showers: Alpha Cygnids and Delphinids. The
lack of these radiants in the artificial database and their existence in the
real observations suggests that Alpha Cygnids and Delphinids are the real
showers and their radiants could not be formed as an effect of intersections of
back prolongated paths of meteors belonging to other showers.


title: How good are the predictions for oscillation frequencies

abstract:
  We have used available intermediate degree p-mode frequencies for the solar
cycle 23 to check the validity of previously derived empirical relations for
frequency shifts (Jain et al.: 2000, Solar Phys., 192, 487). We find that the
calculated and observed frequency shifts during the rising phase of the cycle
23 are in good agreement. The observed frequency shift from minimum to maximum
of this cycle as calculated from MDI frequency data sets is 251 $\pm$ 7 nHz and
from GONG data is 238 $\pm$ 11 nHz. These values are in close agreement with
the empirically predicted value of 271 $\pm$ 22 nHz.


title:
Variation of solar irradiance and mode frequencies during Maunder
  minimum

abstract:
  Using the sunspot numbers reported during the Maunder minimum and the
empirical relations between the mode frequencies and solar activity indices,
the variations in the total solar irradiance and 10.7 cm radio flux for the
period 1645 to 1715 is estimated. We find that the total solar irradiance and
radio flux during the Maunder minimum decreased by 0.19% and 52% respectively,
as compared to the values for solar cycle 22.


title:
Convective intensification of magnetic flux tubes in stellar
  photospheres

abstract:
  The convective collapse of thin magnetic flux tubes in the photospheres of
sun-like stars is investigated using realistic models of the superadiabatic
upper convection zone layers of these stars. The strengths of convectively
stable flux tubes are computed as a function of surface gravity and effective
temperature. We find that while stars with T$_{eff}\ge$ 5500 K and log $g$$\ge$
4.0 show flux tubes highly evacuated of gas, and hence strong field strengths,
due to convective collapse, cooler stars exhibit flux tubes with lower field
strengths. Observations reveal the existence of field strengths close to
thermal equipartition limits even in cooler stars, implying highly evacuated
tubes, for which we suggest possible reasons.


title: Imaging and spectroscopy of the faint remnant G 114.3+0.3

abstract:
  We present the first calibrated CCD images of the faint supernova remnant G
114.3+0.3 in the emission lines of [OII], [OIII], Halpha+[NII] and [SII]. The
deep low ionization CCD images reveal diffuse emission in the south and central
areas of the remnant. These are correlated with areas of intense radio
emission, while estimates of the [SII]/Halpha ratio suggest that the detected
emission originates from shock heated gas. In the medium ionization image of
[OIII] we discovered a thin filament in the south matching very well the outer
radio contours. This filament is not continuous over its total extent but shows
variations in the intensity, mainly in the south-west suggesting inhomogeneous
interstellar clouds. Deep long-slit spectra were also taken along the [OIII]
filament clearly identifying the observed emission as emission from shock
heated gas. The Halpha emission is a few times 10^(-17) erg s^(-1) cm^(-2)
arcsec^(-2), while the variations seen in the [OIII] flux suggest shock
velocities into the interstellar clouds around or below 100 km/s. The sulfur
line ratio approaches the low density limit implying electron densities less
than ~500 cm^(-3).


title:
ESO Imaging Survey. Exploring the optical/infrared imaging data of
  CDF-S: Point Sources

abstract:
  This paper describes the methodology currently being implemented in the EIS
pipeline for analysing optical/infrared multi-colour data. The aim is to
identify different classes of objects as well as possible undesirable features
associated with the construction of colour catalogues. The classification
method used is based on the xi^2-fitting of template spectra to the observed
SEDs, as measured through broad-band filters. Its main advantage is the
simultaneous use of all colours, properly weighted by the photometric errors.
In addition, it provides basic information on the properties of the classified
objects (eg redshift, effective temperature). These characteristics make the
xi^2-technique ideal for handling large multi-band datasets. The results are
compared to the more traditional colour-colour selection and, whenever
possible, to model predictions. In order to identify objects with odd colours,
either associated with rare populations or to possible problems in the
catalogue, outliers are searched for in the multi-dimensional colour space
using a nearest-neighbour criterion. Outliers with large xi^2-values are
individually inspected to further investigate their nature. The tools developed
are used for a preliminary analysis of the multi-colour point source catalogue
constructed from the optical/infrared imaging data obtained for the Chandra
Deep Field South (CDF-S). These data are publicly available, representing the
first installment of the ongoing EIS Deep Public Survey.


title: Patterns in the weak shear 3-point correlation function

abstract:
  We explore the scale and angular dependence of the cosmic shear three-point
correlation function. The shear field is found to have a much more complex
three-point function than the convergence field, but it also exhibits specific
motifs which draw signatures of gravitational lensing. Exact shear patterns are
inferred analytically for some geometrical shear triplets configurations, when
simple interpretations can be derived. A more complete description of their
geometrical properties has then been carried out from ray-tracing numerical
simulations and simple models. These patterns reveal typical features that can
be utilized for non-gaussian signal detection in cosmic shear surveys. We test
the robustness of these properties against complex noise statistics and
non-trivial survey topologies. From these conclusive checks, we predict that
the VIRMOS-DESCART survey should allow a detection of a non-gaussian signal
with a comfortable significance for a low matter density Universe.


title: Young close isolated compact objects

abstract:
  We suggest that the seven radio-quiet isolated neutron stars observed with
ROSAT are young cooling objects associated to recent near-by supernova
explosions which formed runaway stars and the Local Bubble, affecting the
topology of the interstellar medium in the vicinity of the Sun (within a few
hundred parsecs). In the aftermath of these explosions, a few black holes might
have been formed, according to the local initial mass function. We thus discuss
the possibility of determining approximate positions of close-by isolated black
holes using data on runaway stars and simple calculations of binary evolution
and disruption.


title: Stellar Orbits Near Sagittarius A*

abstract:
  We present new SHARP/NTT stellar proper motion and accelaration data covering
an interval from 1992 to 2000: 1) We combine the high precision but shorter
time scale NIRC/Keck data with the lower precision but longer time scale
SHARP/NTT data set; 2) We statistically correct the observed accelerations for
geometrical projection effects; 3) We exclude star S8 from the analysis of the
amount and position of the central mass. We show that the stars S2, and most
likely S1 and S8 as well, are on bound, fairly inclined ($60^o<i<80^o$), and
eccentric ($0.4<e<0.95$) orbits around a central dark mass. The combination of
both data sets results in a position of this central mass of 48$^{+54}_{-24}$
$mas$ E and 18$^{+42}_{-61}$ $mas$ S of the nominal radio position of Sgr A*.
The mean statistically corrected enclosed mass derived from accelerations is
M_acc=(5 +/- 3) x 10^6 solar masses with current radial separations of S1 and
S2 from SgrA* of about $8-10 mpc$. This enclosed mass estimate is derived from
individual stellar orbits as close to the massive black hole at the center of
the Milky Way as currently possible. Although the uncertainties are large this
estimate is fully consistent with the enclosed mass range of (2.6-3.3)x10^6
solar masses derived by Genzel et al. (2000) from radial and/or proper motion
velocities of a homogenized sample of sources.


title:
Detection of non-Gaussian Signatures in the VIRMOS-DESCART Lensing
  Survey

abstract:
  We have detected non-Gaussian signatures in the VIRMOS-DESCART weak lensing
survey from a measurement of the three-point shear correlation function,
following the method developed by Bernardeau et al. (2002). We obtain a
2.4-sigma signal over four independent angular bins, or equivalently, a
4.9-sigma confidence level detection with respect to measurements errors on
scale of about 2 to 4 arcmin. The amplitude and the shape of the signal are
consistent with theoretical expectations obtained from ray-tracing simulations.
This result supports the idea that the measure corresponds to a cosmological
signal due to the gravitational instability dynamics. Its properties could be
used to put constraints on the cosmological parameters, in particular on the
density parameter of the Universe, but the error level as well as the cosmic
variance are still too large to permit secure conclusions.


title: The Local Interstellar Ultraviolet Radiation Field

abstract:
  I have used the Hipparcos Input Catalog, together with Kurucz model stellar
atmospheres, and information on the strength of the interstellar extinction, to
create a model of the expected intensity and spectral distribution of the local
interstellar ultraviolet radiation field, under various assumptions concerning
the albedo a of the interstellar grains. (This ultraviolet radiation field is
of particular interest because of the fact that ultraviolet radiation is
capable of profoundly affecting the chemistry of the interstellar medium.) By
comparing my models with the observations, I am able to conclude that the
albedo a of the interstellar grains in the far ultraviolet is very low, perhaps
a = 0.1. I also advance arguments that my present determination of this albedo
is much more reliable than any of the many previous (and conflicting)
ultraviolet interstellar grain albedo determinations. Beyond this, I show that
the ultraviolet background radiation that is observed at high galactic
latitudes must be extragalactic in origin, as it cannot be backscatter of the
interstellar radiation field.


title: Do Type Ia Supernovae prove Lambda > 0 ?

abstract:
  The evidence for positive cosmological constant $\Lambda$ from Type Ia
supernovae is reexamined.
  Both high redshift supernova teams are found to underestimate the effects of
host galaxy extinction. The evidence for an absolute magnitude- decay time
relation is much weakened if supernovae not observed before maximum light are
excluded. Inclusion of such objects artificially supresses the scatter about
the mean relation.
  With a consistent treatment of host galaxy extinction and elimination of
supernovae not observed before maximum, the evidence for a positive lambda is
not very significant (3-4 $\sigma$). A factor which may contribute to apparent
faintness of high z supernovae is evolution of the host galaxy extinction with
z.
  The Hubble diagram using all high z distance estimates, including SZ clusters
and gravitational lens time-delay estimates, does not appear inconsistent with
an $\Omega_o$ = 1 model.
  Although a positive $\Lambda$ can provide an, albeit physically unmotivated,
resolution of the low curvature implied by CMB experiments and evidence that
$\Omega_o <$ 1 from large-scale structure, the direct evidence from Type Ia
supernovae seems at present to be inconclusive.


title: Obscuring Material around Seyfert Nuclei with Starbursts

abstract:
  The structure of obscuring matter in the environment of active galactic
nuclei with associated nuclear starbursts is investigated using 3-D
hydrodynamical simulations. Simple analytical estimates suggest that the
obscuring matter with energy feedback from supernovae has a torus-like
structure with a radius of several tens of parsecs and a scale height of about
10 pc. These estimates are confirmed by the fully non-linear numerical
simulations, in which the multi-phase inhomogeneous interstellar matter and its
interaction with the supernovae are consistently followed. The globally stable,
torus-like structure is highly inhomogeneous and turbulent. To achieve the high
column densities (> 10^{24} cm^{-2}) as suggested by observations of some
Seyfert 2 galaxies with nuclear starbursts, the viewing angle should be larger
than about 70 degree from the pole-on for a 10^8 solar mass massive black hole.
Due to the inhomogeneous internal structure of the torus, the observed column
density is sensitive to the line-of-sight, and it fluctuates by a factor of
order 100. The covering fraction for N > 10^{23} cm^{-2} is about 0.4. The
average accretion rate toward R < 1 pc is 0.4 solar mass/yr, which is boosted
to twice that in the model without the energy feedback.


title: On the validity of the discrete ordinates method in spherical geometry

abstract:
  The discrete ordinates method with angular parameters is discussed in light
of the recent extension of its underlying hypothesis. The analysis shows that
the method, although it compares very well with the trajectory of photons
model, it addresses a boundary value problem different from the problem of flow
of energy in the interior of spheres


title: Cosmological Implications of Massive Neutrinos

abstract:
  The massive neutrinos gravitational infall and their inprints left on the CMB
temperature and matter density fluctuations power spectra are analysed taking
into account the massive neutrino properties: the mass degeneracy, the phase
space mixing, the lepton asymmetry.


title: The Luminosity Dependence of UV Absorption in AGN

abstract:
  We describe the results of a survey of the UV absorption properties of the
Boroson & Green sample of AGN, which extends from the Seyfert (M_V ~ -21) to
the luminous quasar (M_V ~ -27) level. The survey is based mostly on HST
archival data available for >~ 1/2 of the 87 sample objects. Our main result is
that soft X-ray weak quasars (SXWQs, 10 AGN with alpha_ox<= -2) show the
strongest UV absorption at a given luminosity, and their maximum outflow
velocity, v_max, is strongly correlated with M_V (r_S=-0.95). This suggests
that v_max is largely set by the luminosity, as expected for radiation-pressure
driven outflows. Luminous SXWQs have preferentially low [O III] luminosity,
which suggests they are physically distinct from unabsorbed AGN, while
non-SXWQs with UV absorption are consistent with being drawn from the
unabsorbed AGN population. We also find an indication that v_max/v_BLR
increases with L/L_Edd, as expected for radiation-pressure driven outflows.
This relation and the v_max vs. M_V relation may indicate that the
radiation-pressure force multiplier increases with luminosity, and that the
wind launching radius in non-SXWQs is ~10 times larger than in SXWQs.


title: A Very Sensitive 21cm Survey for Galactic High-Velocity HI

abstract:
  Very sensitive HI 21cm observations have been made in 860 directions at dec
>= -43deg in search of weak, Galactic, high-velocity HI emission lines at
moderate and high Galactic latitudes. One-third of the observations were made
toward extragalactic objects. The median 4-sigma detection level is NHI =
8x10^{17} cm^-2 over the 21' telescope beam. High-velocity HI emission is
detected in 37% of the directions; about half of the lines could not have been
seen in previous surveys. The median FWHM of detected lines is 30.3 km/s. High-
velocity HI lines are seen down to the sensitivity limit of the survey implying
that there are likely lines at still lower values of NHI. The weakest lines
have a kinematics and distribution on the sky similar to that of the strong
lines, and thus do not appear to be a new population. Most of the emission
originates from objects which are extended over several degrees; few appear to
be compact sources. At least 75%, and possibly as many as 90%, of the lines are
associated with one of the major high-velocity complexes. The Magellanic Stream
extends at least 10 deg to higher Galactic latitude than previously thought and
is more extended in longitude as well. Although there are many lines with low
column density, their numbers do not increase as rapidly as NHI^-1, so most of
the HI mass in the high-velocity cloud phenomenon likely resides in the more
prominent clouds. The bright HI features may be mere clumps within larger
structures, and not independent objects.


title: A Correlation Between Inclination and Color in the Classical Kuiper Belt

abstract:
  We have measured broadband optical BVR photometry of 24 Classical and
Scattered Kuiper belt objects (KBOs), approximately doubling the published
sample of colors for these classes of objects. We find a statistically
significant correlation between object color and inclination in the Classical
Kuiper belt using our data. The color and inclination correlation increases in
significance after the inclusion of additional data points culled from all
published works. Apparently, this color and inclination correlation has not
been more widely reported because the Plutinos show no such correlation, and
thus have been a major contaminant in previous samples. The color and
inclination correlation excludes simple origins of color diversity, such as the
presence of a coloring agent without regard to dynamical effects.
Unfortunately, our current knowledge of the Kuiper belt precludes us from
understanding whether the color and inclination trend is due to environmental
factors, such as collisional resurfacing, or primordial population effects. A
perihelion and color correlation is also evident, although this appears to be a
spurious correlation induced by sampling bias, as perihelion and inclination
are correlated in the observed sample of KBOs.


title: On the formation of massive stars

abstract:
  We calculate numerically the collapse of slowly rotating, non-magnetic,
massive molecular clumps, which conceivably could lead to the formation of
massive stars. Because radiative acceleration on dust grains plays a critical
role in the clump's dynamical evolution, we utilize a wavelength-dependent
radiation transfer and a three component dust model: amorphous carbon
particles, silicates and "dirty ice"-coated silicates. We do not spatially
resolve the innermost regions of the molecular clump and assume that all
material in the innermost grid cell accretes onto a single object. We introduce
a semi-analytical scheme for augmenting existing evolution tracks of pre-main
sequence protostars by including the effects of accretion. By considering an
open outermost boundary, an arbitrary amount of material could, in principal,
be accreted onto this central star. However, for the three cases considered
(30, 60, and 120 solar masses originally within the computation grid),
radiation acceleration limited the final masses to 31.6, 33.6, and 42.9 solar
masses, respectively, for wavelength-dependent radiation transfer and to 19.1,
20.1, and 22.9 solar masses for comparison simulations with grey radiation
transfer. We demonstrate that massive stars can in principle be formed via
accretion through a disk. We conclude with the warning that a careful treatment
of radiation transfer is a mandatory requirement for realistic simulations of
the formation of massive stars.


title: Galaxy morphology in the rich cluster Abell 2390

abstract:
  We have analysed images of the field of A2390 obtained with the CFHT and HST.
The analysis fits models to bulge and disk components to several hundred
galaxies, with about equal samples from the cluster and field. We also have
assessed and graded asymmetries in the images. The cluster galaxies are
compared in different cluster locations and also compared with field galaxies.
We find that the central old population galaxies are bulge-dominated, while
disk systems have young populations and are found predominantly in the outer
cluster. S0 and bulgy disk galaxies are found throughout, but concentrate in
regions of substructure. Disks of cluster blue galaxies are generally brighter
and smaller than those in the field. We find that the cluster members have a
higher proportion of interacting galaxies than the field sample. Interactions
in the cluster and in the field, as well as cluster infall, appear to inhibit
star-formation in galaxies.