title: An Induction Accelerator of Cosmic Rays on the Axis of an Accretion Disk

abstract:
  The structure and magnitude of the electric field created by a rotating
accretion disk with a poloidal magnetic field is found for the case of a vacuum
approximation along the axis. The accretion disk is modeled as a torus filled
with plasma and the frozen-in magnetic field. The dimensions and location of
the maximum electric field are found, as well as the energy of the accelerated
particles. The gravitational field is assumed to be weak.


title:
Blind separation of noisy Gaussian stationary sources. Application to
  cosmic microwave background imaging

abstract:
  We present a new source separation method which maximizes the likelihood of a
model of noisy mixtures of stationary, possibly Gaussian, independent
components. The method has been devised to address the problem of imaging CMB
anisotropies. It works in the spectral domain where, thanks to two simple
approximations, the likelihood assumes a simple form which is easy to handle
(low dimensional sufficient statistics) and to maximize (via the EM algorithm).


title: Correlated timing and spectral behavior of 4U 1705-44

abstract:
  We follow the timing properties of the neutron star low-mass X-ray binary
system 4U 1705-44 in different spectral states, as monitored by the Rossi X-ray
Timing Explorer over about a month. We fit the power density spectra using
multiple Lorentzians. We show that the characteristic frequencies of these
Lorentzians, when properly identified, fit within the correlations previously
reported. The time evolution of these frequencies and their relation with the
parameters of the energy spectra reported in Barret & Olive (2002) are used to
constrain the accretion geometry changes. The spectral data were fitted by the
sum of a blackbody and a Comptonized component and were interpreted in the
framework of a truncated accretion disk geometry, with a varying truncation
radius. If one assumes that the characteristic frequencies of the Lorentzians
are some measure of this truncation radius, as in most theoretical models, then
the timing data presented here strengthen the above interpretation. The soft to
hard and hard to soft transitions are clearly associated with the disk receding
from and approaching the neutron star respectively. During the transitions,
correlations are found between the Lorentzian frequencies and the flux and
temperature of the blackbody, which is thus likely to be coming from the disk.
On the other hand, in the hard state, the characteristic Lorentzians
frequencies which are at the lowest, remained nearly constant despite
significant evolution of the spectra parameters. The disk no longer contributes
to the X-ray emission, and the blackbody is now likely to be emitted by the
neutron star surface which is providing the seed photons for the
Comptonization.


title: Ground Based VLBI Facilities -- the European and Global VLBI Network

abstract:
  There are at least four well known Very Long Baseline Interferometer (VLBI)
networks that provide open access to astronomers around the world. These
include the EVN, VLBA, CMVA and APT/LBA. In this paper I have chosen to focus
on a sub-set of these facilities, in particular the European VLBI Network, both
in stand-alone mode but also as a major component of a Global VLBI Network,
involving MERLIN and the VLBA.


title: Spectral energy distributions of selfgravitating QSO discs

abstract:
  We calculate spectral energy distributions (SEDs) of steady accretion discs
at high accretion rates, as appropriate for bright QSOs, under the assumption
that the outer parts are heated sufficiently to maintain marginal gravitational
stability, presumably by massive stars formed within the disc. The SED is
independent of the nature of these auxiliary sources if their inputs are
completely thermalized. Standard assumptions are made for angular momentum
transport, with an alpha parameter less than unity. With these prescriptions,
the luminosity of the disc is sensitive to its opacity, in contrast to standard
discs powered by release of orbital energy alone. Compared to the latter, our
discs have a broader SED, with a second peak in the near-infrared that is
energetically comparable to the blue bump. The energy in the second peak
increases with the outer radius of the disc, provided that the accretion rate
is constant with radius. By comparing our computed SEDs with observed ones, we
limit the outer radius of the disc to be less than 10^5 Schwarzschild radii, or
about one parsec, in a typical QSO. We also discuss some properties of our
minimum-Q discs in the regions where auxiliary heating is dominant (10^3-10^5
Schwarzschild radii).


title: Solar Surface Magneto-Convection

abstract:
  Magneto-convection simulations on meso-granule and granule scales near the
solar surface are used to study small scale dynamo activity, the emergence and
disappearance of magnetic flux tubes, and the formation and evolution of
micropores.
  From weak seed fields, convective motions produce highly intermittent
magnetic fields in the intergranular lanes which collect over the boundaries of
the underlying meso-granular scale cells. Instances of both emerging magnetic
flux loops and magnetic flux disappearing from the surface occur in the
simulations. We show an example of a flux tube collapsing to kG field strength
and discuss how the nature of flux disappearance can be investigated. Observed
stokes profiles of small magnetic structures are severely distorted by
telescope diffraction and seeing.
  Because of the strong stratification, there is little recycling of plasma and
field in the surface layers. Recycling instead occurs by exchange with the deep
layers of the convection zone. Plasma and field from the surface descend
through the convection zone and rise again toward the surface. Because only a
tiny fraction of plasma rising up from deep in the convection zone reaches the
surface due to mass conservation, little of the magnetic energy resides in the
near surface layers. Thus the dynamo acting on weak incoherent fields is
global, rather than a local surface dynamo.


title:
Hot dust in normal star-forming galaxies: JHKL' photometry of the ISO
  Key Project sample

abstract:
  We present JHK and 3.8-micron photometry of 26 galaxies in the Infrared Space
Observatory (ISO) Normal Galaxy Key Project (KP) sample and of seven normal
ellipticals with the aim of investigating the origin of the 4-micron emission.
The majority of the KP galaxies, and all the ellipticals, have K-L<~1.0,
consistent with stellar photospheres plus moderate dust extinction. Ten of the
26 KP galaxies have K-L>~1.0, corresponding to a flat or rising 4-micron
continuum, consistent with significant emission from hot dust at 600-1000K. K-L
is anticorrelated with ISO flux ratio F_{6.75}/F_{15}, weakly correlated with
line ratio [OI]/[CII], but not with [CII]/FIR or IRAS ratio F_{60}/F_{100}.
Photodissociation-region models for these galaxies show that the hot dust
responsible for red K-L resides in regions of high pressure and intense
far-ultraviolet radiation field. Taken together, these results suggest that
star formation in normal star-forming galaxies can assume two basic forms: an
``active'', relatively rare, mode characterized by hot dust, suppressed
Aromatic Features in Emission (AFEs), high pressure, and intense radiation
field; and the more common ``passive'' mode that occurs under more quiescent
physical conditions, with AFEs, and without hot dust. The occurrence of these
modes appears to only weakly depend on the star-formation rate per unit area.
Passive star formation over large scales makes up the bulk of star-forming
activity locally, while the ``active'' regime may dominate at high redshifts.


title: Orbital periods of twenty two subdwarf B stars

abstract:
  Subdwarf B (sdB) stars are thought to be core helium burning stars with low
mass hydrogen envelopes. In recent years it has become clear that many sdB
stars lose their hydrogen through interaction with a binary companion and
continue to reside in binary systems today. In this paper we present the
results of a programme to measure orbital parameters of binary sdB stars. We
determine the orbits of 22 binary sdB stars from 424 radial velocity
measurements, raising the sample of sdBs with known orbital parameters to 38.
We calculate lower limits for the masses of the companions of the sdB stars
which, when combined with the orbital periods of the systems, allow us to
discuss approximate evolutionary constraints. We find that a formation path for
sdB stars consisting of mass transfer at the tip of the red giant branch
followed by a common envelope phase explains most, but not all of the observed
systems. It is particularly difficult to explain both long period systems and
short period, massive systems. We present new measurements of the effective
temperature, surface density and surface helium abundance for some of the sdB
stars by fitting their blue spectra. We find that two of them (PG0839+399 and
KPD1946+4340) do not lie in the Extreme Horizontal Branch (EHB) band indicating
that they are post-EHB stars.


title: Discovery of the heavily obscured supernova 2002cv

abstract:
  On the 13th of May 2002, supernova 2002cv was discovered using a
near-infrared camera working at the AZT-24 1.1m telescope at Campo Imperatore
(AQ-Italy). After the infrared detection a simultaneous photometric follow-up
was started at optical wavelengths. The preliminary results confirm a heavily
obscured object with a V-K color not lower than 6 magnitudes, making SN 2002cv
the most reddened supernova ever observed. This finding, along with the recent
discovery of another obscured supernova, suggests a critical revision of the
rates known to date. The estimate of the visual extinction and the light curves
are provided here. These latter indicate that our SN 2002cv observations are
the earliest available for a type-Ia supernova at IR wavelengths.


title:
Separating cosmic shear from intrinsic galaxy alignments: correlation
  function tomography

abstract:
  During the past few years, secure detections of cosmic shear have been
obtained, manifest in the correlation of the observed ellipticities of
galaxies. Constraints have already been placed on cosmological parameters, such
as the normalisation of the matter power spectrum sigma_8. One possible
systematic contaminant of the lensing correlation signal arises from intrinsic
galaxy alignment, which is still poorly constrained. Unlike lensing, intrinsic
correlations only pertain to galaxies with small physical separations, the
correlation length being a few Mpc. We present a new method that harnesses this
property, and isolates the lensing and intrinsic components of the galaxy
ellipticity correlation function using measurements between different redshift
slices. The observed signal is approximated by a set of template functions,
making no strong assumptions about the amplitude or correlation length of any
intrinsic alignment. We also show that the near-degeneracy between the matter
density parameter Omega_m and sigma_8 can be lifted using correlation function
tomography, even in the presence of an intrinsic alignment signal.


title:
Infrared spectroscopy around 4micron of Seyfert 2 galaxies: Obscured
  broad line regions and coronal lines

abstract:
  The state of the matter that is obscuring a small circumnuclear region in AGN
can be probed by observations of its broad emission lines. Infrared lines are
particularly useful since they penetrate significant columns of obscuring
matter, the properties of which can be constrained by comparing infrared and
X-ray obscuration. We report on new 4um spectroscopy of a sample of 12 Seyfert
2 galaxies, probing for broad components to the Brackett alpha 4.05um line.
Broad components are observed in 3 to 4 objects. All objects with a broad
component exhibit relatively low X-ray obscuring columns, and our results are
consistent with a Galactic ratio of 4um obscuration to the BLR and X-ray
column. In combination with observations of a NON-Galactic ratio of VISUAL
obscuration of BLRs and X-ray obscuring column in Seyferts, and interpreted in
a unified AGN scheme, this result can be reconciled with two interpretations.
Either the properties of dust near the AGN are modified towards larger grains,
for example through coagulation, in a way that significantly flattens the
optical/IR extinction curve, or the ratio of dust obscuration to X-ray column
varies for different viewing angles with respect to the axis of symmetry of the
putative torus. Our spectra also provide a survey of emission in the [SiIX]
3.94um coronal line, finding variation by an order of magnitude in its ratio to
Br alpha. The first extragalactic detection of the [CaVII] 4.09um and [CaV]
4.16um coronal lines is reported in the spectrum of the Circinus galaxy.


title: Measuring Polarization with DASI

abstract:
  We describe an experiment to measure the polarization of the Cosmic Microwave
Background (CMB) with the Degree Angular Scale Interferometer (DASI), a compact
microwave interferometer optimized to detect CMB anisotropy at multipoles 140
to 900. The telescope has operated at the Amundsen-Scott South Pole research
station since 2000 January. The telescope was retrofit as a polarimeter during
the 2000--2001 austral summer, and throughout the 2001 and 2002 austral winters
has made observations of the CMB with sensitivity to all four Stokes
parameters. The telescope performance has been extensively characterized
through observations of artificial sources, the Moon, and polarized and
unpolarized Galactic sources. In 271 days of observation, DASI has differenced
the CMB fluctuations in two fields to an rms noise level of 2.8 uK.


title: A Distributed Control System for Rapid Astronomical Transient Detection

abstract:
  The Rapid Telescope for Optical Response (RAPTOR) program consists of a
network of robotic telescopes dedicated to the search for fast optical
transients. The pilot project is composed of three observatories separated by
approximately 38 kilometers located near Los Alamos, New Mexico. Each of these
observatories is composed of a telescope, mount, enclosure, and weather
station, all operating robotically to perform individual or coordinated
transient searches. The telescopes employ rapidly slewing mounts capable of
slewing a 250 pound load 180 degrees in under 2 seconds with arcsecond
precision. Each telescope consists of wide-field cameras for transient
detection and a narrow-field camera with greater resolution and sensitivity.
The telescopes work together by employing a closed-loop system for transient
detection and follow-up. Using the combined data from simultaneous
observations, transient alerts are generated and distributed via the Internet.
Each RAPTOR telescope also has the capability of rapidly responding to external
transient alerts received over the Internet from a variety of ground-based and
satellite sources. Each observatory may be controlled directly, remotely, or
robotically while providing state-of-health and observational results to the
client and the other RAPTOR observatories. We discuss the design and
implementation of the spatially distributed RAPTOR system.


title: Detection of Polarization in the Cosmic Microwave Background using DASI

abstract:
  We report the detection of polarized anisotropy in the Cosmic Microwave
Background radiation with the Degree Angular Scale Interferometer (DASI),
located at the Amundsen-Scott South Pole research station. Observations in all
four Stokes parameters were obtained within two 3.4 FWHM fields separated by
one hour in Right Ascension. The fields were selected from the subset of fields
observed with DASI in 2000 in which no point sources were detected and are
located in regions of low Galactic synchrotron and dust emission. The
temperature angular power spectrum is consistent with previous measurements and
its measured frequency spectral index is -0.01 (-0.16 -- 0.14 at 68%
confidence), where 0 corresponds to a 2.73 K Planck spectrum. The power
spectrum of the detected polarization is consistent with theoretical
predictions based on the interpretation of CMB anisotropy as arising from
primordial scalar adiabatic fluctuations. Specifically, E-mode polarization is
detected at high confidence (4.9 sigma). Assuming a shape for the power
spectrum consistent with previous temperature measurements, the level found for
the E-mode polarization is 0.80 (0.56 -- 1.10), where the predicted level given
previous temperature data is 0.9 -- 1.1. At 95% confidence, an upper limit of
0.59 is set to the level of B-mode polarization with the same shape and
normalization as the E-mode spectrum. The TE correlation of the temperature and
E-mode polarization is detected at 95% confidence, and also found to be
consistent with predictions. These results provide strong validation of the
underlying theoretical framework for the origin of CMB anisotropy and lend
confidence to the values of the cosmological parameters that have been derived
from CMB measurements.


title:
The Broad-band Optical Properties of Galaxies with Redshifts 0.0 < z <
  0.2

abstract:
  Using photometry and spectroscopy of 144,609 galaxies from the Sloan Digital
Sky Survey, we present bivariate distributions of pairs of seven galaxy
properties: four optical colors, surface brightness, radial profile shape as
measured by the Sersic index, and absolute magnitude. In addition, we present
the dependence of local galaxy density (smoothed on 8 h^{-1} Mpc scales) on all
of these properties. Several classic, well-known relations among galaxy
properties are evident at extremely high signal-to-noise ratio: the color-color
relations of galaxies, the color-magnitude relations, the magnitude-surface
brightness relation, and the dependence of density on color and absolute
magnitude. We show that most of the i-band luminosity density in the universe
is in the absolute magnitude and surface brightness ranges used. Some of the
relationships between parameters, in particular the color--magnitude relations,
show stronger correlations for exponential galaxies and concentrated galaxies
taken separately than for all galaxies taken together. We provide a simple set
of fits of the dependence of galaxy properties on luminosity for these two sets
of galaxies.


title:
Heartbeat of the Mouse: a young radio pulsar associated with the
  axisymmetric nebula G359.23-0.82

abstract:
  We report the discovery of PSR J1747-2958, a radio pulsar with period P = 98
ms and dispersion measure DM = 101 pc/cc, in a deep observation with the Parkes
telescope of the axially-symmetric "Mouse" radio nebula (G359.23-0.82). Timing
measurements of the newly discovered pulsar reveal a characteristic age Pdt/2dP
= 25 kyr and spin-down luminosity dE/dt = 2.5e36 erg/s. The pulsar (timing)
position is consistent with that of the Mouse's "head". The distance derived
from the DM, ~2 kpc, is consistent with the Mouse's distance limit from HI
absorption, < 5.5 kpc. Also, the X-ray energetics of the Mouse are compatible
with being powered by the pulsar. Therefore we argue that PSR J1747-2958,
moving at supersonic speed through the local interstellar medium, powers this
unusual non-thermal nebula. The pulsar is a weak radio source, with
period-averaged flux density at 1374 MHz of 0.25 mJy and luminosity ~1 mJy
kpc^2.


title:
Synthetic High-Resolution Line Spectra of Star-Forming Galaxies Below
  1200A

abstract:
  We have generated a set of far-ultraviolet stellar libraries using spectra of
OB and Wolf-Rayet stars in the Galaxy and the Large and Small Magellanic Cloud.
The spectra were collected with the Far Ultraviolet Spectroscopic Explorer and
cover a wavelength range from 1003.1 to 1182.7A at a resolution of 0.127A. The
libraries extend from the earliest O- to late-O and early-B stars for the
Magellanic Cloud and Galactic libraries, respectively. Attention is paid to the
complex blending of stellar and interstellar lines, which can be significant,
especially in models using Galactic stars. The most severe contamination is due
to molecular hydrogen. Using a simple model for the H$_2$ line strength, we
were able to remove the molecular hydrogen lines in a subset of Magellanic
Cloud stars. Variations of the photospheric and wind features of CIII 1176, OVI
1032, 1038, PV 1118, 1128, and SIV 1063, 1073, 1074 are discussed as a function
of temperature and luminosity class. The spectral libraries were implemented
into the LavalSB and Starburst99 packages and used to compute a standard set of
synthetic spectra of star-forming galaxies. Representative spectra are
presented for various initial mass functions and star formation histories. The
valid parameter space is confined to the youngest ages of less than 10 Myr for
an instantaneous burst, prior to the age when incompleteness of spectral types
in the libraries sets in. For a continuous burst at solar metallicity, the
parameter space is not limited. The suite of models is useful for interpreting
the restframe far-ultraviolet in local and high-redshift galaxies.


title: Relativistic Jets from Collapsars: Gamma-Ray Bursts

abstract:
  Growing observational evidence supports the proposition that gamma-ray bursts
(GRBs) are powered by relativistic jets from massive helium stars whose cores
have collapsed to black holes and an accretion disk (collapsars). We model the
propagation of relativistic jets through the stellar progenitor and its wind
using a two-dimensional special relativistic hydrodynamics code based on the
PPM formalism. The jet emerges from the star with a plug in front and a cocoon
surrounding it. During its propagation outside the star, the jet gains high
Lorentz factor as its internal energy is converted into kinetic energy while
the cocoon expands both outwards and sideways. External shocks between the
cocoon and the stellar wind can produce $\gamma$-ray and hard x-ray transients.
The interaction of the jet beam and the plug will also affect both of them
substantially, and may lead to short-hard GRBs. Internal shocks in the jet
itself may make long-soft GRBs.


title: Axisymmetric Dynamical Models of the Central Regions of Galaxies

abstract:
  We present axisymmetric, orbit superposition models for 12 galaxies using
data taken with the Hubble Space Telescope (HST) and ground-based
observatories. In each galaxy, we detect a central black hole (BH) and measure
its mass to accuracies ranging from 10% to 70%. We demonstrate that in most
cases the BH detection requires both the HST and ground-based data. Using the
ground-based data alone does provide an unbiased measure of the BH mass
(provided they are fit with fully general models), but at a greatly reduced
significance. The most significant correlation with host galaxy properties is
the relation between the BH mass and the velocity dispersion of the host
galaxy; we find no other equally strong correlation, and no second parameter
that improves the quality of the mass-dispersion relation. We are also able to
measure the stellar orbital properties from these general models. The most
massive galaxies are strongly biased to tangential orbits near the BH,
consistent with binary BH models, while lower-mass galaxies have a range of
anisotropies, consistent with an adiabatic growth of the BH.


title:
The Ionized Gas and Nuclear Environment in NGC 3783 II. Averaged
  HST/STIS and FUSE Spectra

abstract:
  We present observations of the intrinsic absorption in the Seyfert 1 galaxy
NGC 3783 obtained with the STIS/HST and FUSE. We have coadded multiple STIS and
FUSE observations to obtain a high S/N averaged spectrum spanning 905-1730 A.
The averaged spectrum reveals absorption in O VI, N V, C IV, N III, C III and
the Lyman lines up to LyE in the three blueshifted kinematic components
previously detected in the STIS spectrum (at radial velocities of -1320, -724,
and -548 km/s). The highest velocity component exhibits absorption in Si IV. We
also detect metastable C III* in this component, indicating a high density in
this absorber. We separate the individual covering factors of the continuum and
emission-line sources as a function of velocity in each kinematic component
using the LyA and LyB lines. Additionally, we find that the continuum covering
factor varies with velocity within the individual kinematic components,
decreasing smoothly in the wings of the absorption by at least 60%. The
covering factor of Si IV is found to be less than half that of H I and N V in
the high velocity component. Additionally, the FWHM of N III and Si IV are
narrower than the higher ionization lines in this component. These results
indicate there is substructure within this absorber. We derive a lower limit on
the total column (N_H>=10^{19}cm^{-2}) and ionization parameter (U>=0.005) in
the low ionization subcomponent of this absorber. The metastable-to-total C III
column density ratio implies n_e~10^9 cm^{-3} and an upper limit on the
distance of the absorber from the ionizing continuum of R<=8x10^{17} cm.


title:
Thermal OH (1667/65 MHz) Absorption and Nonthermal OH (1720 MHz)
  Emission Towards the W28 Supernova Remnant

abstract:
  The W28 supernova remnant is an excellent prototype for observing shocked gas
resulting from the interaction of supernova remnants (SNRs) and adjacent
molecular clouds (MCs). We present two new signatures of shocked molecular gas
in this remnant. One is the detection of main-line extended OH (1667 MHz)
absorption with broad linewidths. The column density of OH estimated from the
optical depth profiles is consistent with a theoretical model in which
  OH is formed behind a C-type shock front. The second is the detection of
extended, weak OH (1720 MHz) line emission with narrow linewidth distributed
throughout the shocked region of W28. These give observational support to the
idea that compact maser sources delineate the brightest component of a much
larger region of main line OH absorption and nonthermal OH (1720 MHz) emission
tracing the global structure of shocked molecular gas. Main line OH (1665/67)
absorption and extended OH (1720 MHz) emission line studies can serve as
powerful tools to detect SNR-MC interaction even when bright OH (1720 MHz)
masers are absent.


title:
Constraints on the generalized Chaplygin gas from supernovae
  observations

abstract:
  We explore the implications of type Ia supernovae (SNIa) observations on flat
cosmological models whose matter content is an exotic fluid with equation of
state, p=-M^(4(a+1))/rho^a. In this scenario, a single fluid component may
drive the Universe from a nonrelativistic matter dominated phase to an
accelerated expansion phase behaving, first, like dark matter and in a more
recent epoch as dark energy. We show that these models are consistent with
current SNIa data for a rather broad range of parameters. However, future SNIa
experiments will place stringent constraints on these models, and could safely
rule out the special case of a Chaplygin gas (a=1) if the Universe is dominated
by a true cosmological constant.


title: Observation of gamma-rays greater than 10 TeV from Markarian 421

abstract:
  We have observed Markarian 421 in January and March 2001 with the CANGAROO-II
imaging Cherenkov telescope during an extraordinarily high state at TeV
energies. From 14 hours observations at very large zenith angles,
$\sim70^\circ$, a signal of 298 $\pm$ 52 gamma-ray--like events (5.7 $\sigma$)
was detected at $E>10$ TeV, where a higher sensitivity is achieved than those
of usual observations near the zenith, owing to a greatly increased collecting
area. Under the assumption of an intrinsic power-law spectrum, we derived a
differential energy spectrum $dN/dE =
  (3.3 \pm 0.9_{stat.} \pm 0.3_{syst.})\times10^{-13} (E/10 {Te V})^{-(4.0
^{+0.9}_{-0.6}_{stat.} \pm 0.3_{syst.})}$ ph./cm$^2$/sec/TeV, which is steeper
than those previously measured around 1 TeV, and supports the evidence for a
cutoff in the spectrum of Markarian 421. However, the 4 $\sigma$ excess at
energies greater than 20 TeV in our data favors a cutoff energy of $\sim$8 TeV,
at the upper end of the range previously reported from measurements at TeV
energies.


title: Time evolution of the fine structure constant

abstract:
  We present a short review of the current quasar (QSO) absorption line
constraints on possible variation of the fine structure constant, alpha =
e^2/(hbar*c). Particular attention is paid to recent optical Keck/HIRES spectra
of 49 absorption systems which indicate a smaller alpha in the past (Murphy et
al. 2001, Webb et al. 2001). Here we present new preliminary results from 128
absorption systems: da/a = (-0.57 +/- 0.10) x 10^{-5} over the redshift range
0.2 < z < 3.7, in agreement with the previous results. Known potential
systematic errors cannot explain these results. We compare them with strong
`local' constraints and discuss other (radio and millimetre-wave) QSO
absorption line constraints on variations in alpha^2 * g_p and alpha^2 * g_p *
m_e/m_p (g_p is the proton g-factor and m_e/m_p is the electron/proton mass
ratio). Finally, we discuss future efforts to rule out or confirm the current
5.7 sigma optical detection.


title:
Analyzing weak lensing of the cosmic microwave background using the
  likelihood function

abstract:
  Future experiments will produce high-resolution temperature maps of the
cosmic microwave background (CMB) and are expected to reveal the signature of
gravitational lensing by intervening large-scale structures. We construct
all-sky maximum-likelihood estimators that use the lensing effect to estimate
the projected density (convergence) of these structures, its power spectrum,
and cross-correlation with other observables. This contrasts with earlier
quadratic-estimator approaches that Taylor-expanded the observed CMB
temperature to linear order in the lensing deflection angle; these approaches
gave estimators for the temperature-convergence correlation in terms of the CMB
three-point correlation function and for the convergence power spectrum in
terms of the CMB four-point correlation function, which can be biased and
non-optimal due to terms beyond the linear order. We show that for sufficiently
weak lensing, the maximum-likelihood estimator reduces to the computationally
less demanding quadratic estimator. The maximum likelihood and quadratic
approaches are compared by evaluating the root-mean-square (RMS) error and bias
in the reconstructed convergence map in a numerical simulation; it is found
that both the RMS errors and bias are of order 1 percent for the case of Planck
and of order 10--20 percent for a 1 arcminute beam experiment. We conclude that
for recovering lensing information from temperature data acquired by these
experiments, the quadratic estimator is close to optimal, but further work will
be required to determine whether this is also the case for lensing of the CMB
polarization field.


title: Mid-Infrared Identification of Faint Submillimeter Sources

abstract:
  Faint submillimeter sources detected with the Submillimeter Common-User
Bolometer Array on the James Clerk Maxwell Telescope have faced an
identification problem due to the telescope's broad beam profile. Here we
propose a new method to identify such submillimeter sources with a mid-infrared
image having a finer point spread function. The Infrared Space Observatory has
provided a very deep 6.7 um image of the Hawaii Deep Field SSA13. All three
faint 850 um sources in this field have their 6.7 um counterparts. They have
been identified with interacting galaxy pairs in optical images. These pairs
are also detected in the radio. Two of them are optically faint and very red
(I>24, I-K>4), one of which has a hard X-ray detection with the Chandra
satellite. As these observing properties are similar to those of local
ultraluminous infrared galaxies, their photometric redshifts are derived based
on submillimeter to mid-infrared flux ratios assuming a spectral energy
distribution (SED) of Arp220. Other photometric redshifts are obtained via
chi^2 minimization between the available photometry data and template SEDs.
Both estimates are in the range z=1-2, in good agreement with a spectroscopic
redshift and a millimetric one. The reconstructed Arp220 SEDs with these
redshift estimates are consistent with all the photometry data except Chandra's
hard X-ray detection. The sources would be a few times more luminous than
Arp220. With an assumption that AGN contributions are negligible, it appears
that extremely high star formation rates are occurring in galaxies at high
redshifts with massive stellar contents already in place.


title:
Observational Strategies of CMB Temperature and Polarization
  Interferometry Experiments

abstract:
  We have simulated the interferometric observation of the Cosmic Microwave
Background (CMB) temperature and polarization fluctuations. We have constructed
data pipelines from the time-ordered raw visibility samples to the CMB power
spectra which utilize the methods of data compression, maximum likelihood
analysis, and optimal subspace filtering. They are customized for three
observational strategies, such as the single pointing, the mosaicking, and the
drift-scanning. For each strategy, derived are the optimal strategy parameters
that yield band power estimates with minimum uncertainty. The results are
general and can be applied to any close-packed array on a single platform such
as the CBI and the forthcoming AMiBA experiments. We have also studied the
effect of rotation of the array platform on the band power correlation by
simulating the CBI single pointing observation. It is found that the band power
anti-correlations can be reduced by rotating the platform and thus densely
sampling the visibility plane. This enables us to increase the resolution of
the power spectrum in the l-space down to the limit of the sampling theorem
(Delta l = 226 = pi / theta), which is narrower by a factor of about sqrt{2}
than the resolution limit (Delta l = 300) used in the recent CBI single
pointing observation. The validity of this idea is demonstrated for a
two-element interferometer that samples visibilities uniformly in the
uv-annulus. From the fact that the visibilities are the Fourier modes of the
CMB field convolved with the beam, a fast unbiased estimator (FUE) of the CMB
power spectra is developed and tested. It is shown that the FUE gives results
very close to those from the quadratic estimator method without requiring large
computer resources even though uncertainties in the results increase.


title: The Henize sample of S stars: IV. New symbiotic stars

abstract:
  The properties of the few symbiotic stars detected among the 66 binary S
stars from the Henize sample are discussed. Two stars (Hen 18 and Hen 121)
exhibit both a strong blue-violet continuum and strong H_alpha emission (FWHM
of 70 km/s), whereas Hen 134 and 137 exhibit weak H_alpha emission. The H_alpha
profiles are typical of non-dusty symbiotic stars belonging to class S-3 as
defined by Van Winckel et al. (1993, A&AS 102, 401). In that class as in the
Henize symbiotic S stars, He I, [N II] or [S II] emission lines are absent,
suggesting that the nebular density is high but the excitation rather low. The
radial velocity of the centre of the H_alpha emission is identical to that of
the companion star (at least for Hen 121 where this can be checked from the
available orbital elements), thus suggesting that the H_alpha emission
originates from gas moving with the companion star. For Hen 121, this is
further confirmed by the disappearance of the ultraviolet Balmer continuum when
the companion is eclipsed by the S star. Hen 121 is thus the second eclipsing
binary star discovered among extrinsic S stars (the first one is HD 35155). A
comparison of the available data on orbital periods and H_alpha emission leads
to the conclusion that H_alpha emission in S stars seems to be restricted to
binary systems with periods in the range 600 - 1000 d, in agreement with the
situation prevailing for red symbiotic stars (excluding symbiotic novae).
Symbiotic S stars are found among the most evolved extrinsic S stars.


title:
CHIANTI - an Atomic Database for Emission Lines. Paper VI: Proton Rates
  and Other Improvements

abstract:
  The CHIANTI atomic database contains atomic energy levels, wavelengths,
radiative transition probabilities and electron excitation data for a large
number of ions of astrophysical interest. Version 4 has been released, and
proton excitation data is now included, principally for ground configuration
levels that are close in energy. The fitting procedure for excitation data,
both electrons and protons, has been extended to allow 9 point spline fits in
addition to the previous 5 point spline fits. This allows higher quality fits
to data from close-coupling calculations where resonances can lead to
significant structure in the Maxwellian-averaged collision strengths. The
effects of photoexcitation and stimulated emission by a blackbody radiation
field in a spherical geometry on the level balance equations of the CHIANTI
ions can now be studied following modifications to the CHIANTI software. With
the addition of H I, He I and N I, the first neutral species have been added to
CHIANTI. Many updates to existing ion data-sets are described, while several
new ions have been added to the database, including Ar IV, Fe VI and Ni XXI.
The two-photon continuum is now included in the spectral synthesis routines,
and a new code for calculating the relativistic free-free continuum has been
added. The treatment of the free-bound continuum has also been updated.


title: Acceleration at z>1?

abstract:
  Most models of dark energy predict the beginning of the accelerated epoch at
z <= 1. However, there are no observational or theoretical evidences in favor
of such a recent start of the cosmic acceleration. In fact, a model of dark
energy coupled to dark matter is explicitely constructed that a) is accelerated
even at high z; b) allows structure formation during acceleration; and c) is
consistent with the type Ia supernovae Hubble diagram, including the farthest
known supernova SN1997ff at z~1.7 . It is shown that the accelerated epoch in
this model could have started as early as z~5.


title:
Water Observed in Red Giant and Supergiant Stars - Manifestation of a
  Novel Picture of the Stellar Atmosphere or else Evidence against the
  Classical Model Stellar Photosphere

abstract:
  We detected the H2O 6.3 micron bands in more than 30 normal red giants stars
from K5III to M8III as well as in some early M supergiants on the SWS spectra
retrieved from the ISO Data Archive. This result, however, shows serious
inconsistency with the present model photospheres which predict H2O only in the
latest M (super)giant stars. Also H2O was once discovered in the early M
(super)giant stars nearly 40 years ago with the balloon-borne telescope named
Stratoscope II. This discovery was so unexpected at that time that it was not
understood correctly and overlooked for a long time. Now, we reflect on our
ignorance of this important discovery during the 40 years and should consider
more seriously the meaning of the rediscovery of water in so many red
(super)giant stars with ISO. In view of the detection of H2O in emission in the
early M supergiant mu Cep as well as in late M giants with ISO, H2O should be
in the outer atmosphere rather than in the photosphere. We propose that the
absorption as well as emission of H2O should be originating in a new component,
which we refer to as molecular sphere. Since the extend atmospheres of red
(super)giants radiate efficiently in the infrared, it is not surprising if the
true structure of the atmospheres of these stars can first be revealed with the
infrared observations especially from space.


title:
Simulations of X-ray spectral/timing properties in a propagation model
  of variability of accreting black holes

abstract:
  A phenomenological model of X-ray variability of accreting black holes is
considered, where the variable emission is attributed to multiple active
regions/perturbations moving radially towards the central black hole. The hard
X-rays are produced by inverse Compton upscattering of soft photons coming from
reprocessing/thermalization of the same hard X-rays. The heating rate of the
Comptonizing plasma is assumed to scale with the rate of dissipation of
gravitational energy while the supply of soft photons is assumed to diminish
towards the center. Two scenarios are considered: (1) an inner hot flow with
outer truncated standard accretion disc and (2) an accretion disc with an
active corona and a thick hot ionized skin. A variant of the model is also
considered, which is compatible with the currently discussed multi-Lorentzian
description of power spectral densities of X-ray lightcurves.
  In the inner hot flow scenario the model can reproduce the observed Fourier
frequency resolved spectra observed in X-ray binaries, in particular the
properties of the reprocessed component as functions of Fourier frequency. In
the accretion disc with ionized skin scenario the reduction of soft photons due
to the ionized skin is insufficient to produce the observed characteristics.


title: Testing the principle of equivalence with Planck surveyor

abstract:
  We consider the effect of the violation of the equivalence principle (VEP) by
the massive neutrino component on the Cosmic Microwave Background angular power
specrum. We show that in the presence of adiabatic and isocurvature primordial
density perturbations the Planck surveyor can place limits on the maximal VEP
by the massive neutrino component at the level of 10^ -5, valid in the general
relativity, for the case in which the gravity is the single source of VEP. This
work has been performed within the framework of the {\sc Planck}/LFI
activities.


title: Viscous diffusion and photoevaporation of stellar disks

abstract:
  The evolution of a stellar disk under the influence of viscous evolution,
photoevaporation from the central source, and photoevaporation by external
stars is studied. We take the typical parameters of TTSs and the Trapezium
Cluster conditions. The photoionizing flux from the central source is assumed
to arise both from the quiescent star and accretion shocks at the base of
stellar magnetospheric columns, along which material from the disk accretes.
The accretion flux is calculated self-consistently from the accretion mass loss
rate. We find that the disk cannot be entirely removed using only viscous
evolution and photoionization from the disk-star accretion shock. However, when
FUV photoevaporation by external massive stars is included the disk is removed
in 10^6 -10^7yr; and when EUV photoevaporation by external massive stars is
included the disk is removed in 10^5 - 10^6yr.
  An intriguing feature of photoevaporation by the central star is the
formation of a gap in the disk at late stages of the disk evolution. As the gap
starts forming, viscous spreading and photoevaporation work in resonance.
  There is no gap formation for disks nearby external massive stars because the
outer annuli are quickly removed by the dominant EUV flux. On the other hand,
at larger, more typical distances (d>>0.03pc) from the external stars the flux
is FUV dominated. As a consequence, the disk is efficiently evaporated at two
different locations; forming a gap during the last stages of the disk
evolution.


title:
The Hamburg/SAO survey for low metallicity blue compact/HII-galaxies
  (HSS-LM). I. The first list of 46 strong-lined galaxies

abstract:
  We present the description and the first results of a new project devoted to
the search for extremely metal-deficient blue compact/HII-galaxies (BCGs) and
to the creation of a well selected large BCG sample with strong emission lines.
Such galaxies should be suitable for reliable determination of their oxygen
abundance through the measurement of the faint [OIII]4363A line. The goals of
the project are two-fold: a) to discover a significant number of new extremely
metal-poor galaxies (Z <= 1/20 Zo), and b) to study the metallicity
distribution of local BCGs. Selection of candidates for follow-up slit
spectroscopy is performed on the database of objective prism spectra of the
Hamburg Quasar Survey. The sky region is limited by delta >= 0 deg. and b^ii <=
-30 deg. In this paper we present the results of the follow-up spectroscopy
conducted with the Russian 6m telescope. The list of observed candidates
contained 52 objects, of which 46 were confirmed as strong-lined BCGs
(EW([OIII]5007) >= 100 A). The remaining five lower excitation ELGs include
three BCGs, and two galaxies classified as SBN (Starburst Nucleus) and DANS
(Dwarf Amorphous Nucleus Starburst). One object is identified as a quasar with
a strong Ly_alpha emission line near 5000 A (z~3). We provide a list with
coordinates, measured radial velocities, B-magnitudes, equivalent widths
EW([OIII]5007) and EW(H_beta) and for the 46 strong-lined BCGs the derived
oxygen abundances 12+log(O/H). The abundances range between 7.42 and 8.4
(corresponding to metallicities between 1/30 and 1/3 Zo). The sample contains
four galaxies with Z < 1/20 Zo, of which three are new discoveries.


title:
BL Lac Identification for the Ultraluminous X-ray Source Observed in the
  Direction of NGC 4698

abstract:
  We report the identification of the optical and radio counterparts of the
ultraluminous X-ray (ULX) source XMMU J124825.9+083020 (NGC4698-ULX1). The
optical spectrum taken with the VLT yields a redshift of z=0.43, which implies
that the ULX is not associated with the nearby galaxy NGC4698. The spectral
energy distribution calculated from the available data indicates that the
source is likely to be a BL Lac object. The possible synchrotron peak at X-ray
energies suggests that this source may be a gamma-ray emitter.


title: Microlensing of strongly interacting binary systems

abstract:
  Many binary systems are in a state of strong interaction, where mass
exchanges, accretion disks, common envelopes provide circumstellar matter which
can have significant effects in microlensing light curves of background
sources. Such chromatic absorption effects provide very interesting information
on the nature of this diffuse matter and the physics of the interaction between
the two stars.


title:
Polarization Properties of Extragalactic Radio Sources and Their
  Contribution to Microwave Polarization Fluctuations

abstract:
  We investigate the statistical properties of the polarized emission of
extragalactic radio sources and estimate their contribution to the power
spectrum of polarization fluctuations in the microwave region. The basic
ingredients of our analysis are the NVSS polarization data, the multifrequency
study of polarization properties of the B3-VLA sample (Mack et al. 2002) which
has allowed us to quantify Faraday depolarization effects, and the 15 GHz
survey by Taylor et al. (2001), which has provided strong constraints on the
high-frequency spectral indices of sources. The polarization degree of both
steep- and flat-spectrum at 1.4 GHz is found to be anti-correlated with the
flux density. The median polarization degree at 1.4 GHz of both steep- and
flat-spectrum sources brighter than $S(1.4 \hbox{GHz})=80 $mJy is $\simeq
2.2%$. The data by Mack et al. (2002) indicate a substantial mean Faraday
depolarization at 1.4 GHz for steep spectrum sources, while the depolarization
is undetermined for most flat/inverted-spectrum sources. Exploiting this
complex of information we have estimated the power spectrum of polarization
fluctuations due to extragalactic radio sources at microwave frequencies. We
confirm that extragalactic sources are expected to be the main contaminant of
Cosmic Microwave Background (CMB) polarization maps on small angular scales. At
frequencies $< 30 $GHz the amplitude of their power spectrum is expected to be
comparable to that of the $E$-mode of the CMB. At higher frequencies, however,
the CMB dominates.


title: Quintessence, Cosmology, and Fanaroff-Riley Type IIB Radio Galaxies

abstract:
  Fanaroff-Riley type IIb (FR IIb) radio galaxies provide a modified standard
yardstick that allows constraints to be placed on global cosmological
parameters. A sample of 20 FR IIb radio galaxies with redshifts between 0 and 2
are compared with the parent population of 70 radio galaxies to determine the
coordinate distance to each source. The coordinate-distance determinations are
used to constrain the current mean mass-energy density of quintessence
$\Omega_q$, the equation of state of the quintessence w, and the current mean
mass-energy density of nonrelativistic matter $\Omega_m$; zero space curvature
is assumed. Radio galaxies alone indicate that the universe is currently
accelerating in its expansion (with 84% confidence); most of the allowed
parameter space falls within the accelerating universe region on the
$\Omega_m$-w plane. This provides verification of the acceleration of the
universe indicated by high-redshift supernovae and suggests that neither method
is plagued by systematic errors. It is found that $\Omega_m$ must be less than
about 0.5 and the equation of state w of the quintessence must lie between
-0.25 and -2.5 at about 90% confidence. Fits of the radio galaxy data constrain
the model parameter $\beta$, which describes a relation between the beam power
of the active galactic nucleus (AGN) and the total energy expelled through
large-scale jets. It is shown that the empirically determined model parameter
is consistent with models in which the outflow results from the electromagnetic
extraction of rotational energy from the central compact object. A specific
relation between the strength of the magnetic field near the AGN and the spin
angular momentum per unit mass of the central compact object is predicted.


title: The picture of our universe: A view from modern cosmology

abstract:
  In this paper we give a pedagogical review of the recent observational
results in cosmology from the study of type Ia supernovae and anisotropies in
the cosmic microwave background. By providing consistent constrainst on the
cosmological parameters, these results paint a concrete picture of our
present-day universe. We present this new picture and show how it can be used
to answer some of the basic questions that cosmologists have been asking for
several decades. This paper is most appropriate for students of general
relativity and/or relativistic cosmology.


title: Cosmic opacity to CMB photons and polarization measurements

abstract:
  Anisotropy data analysis leaves a significant degeneracy between primeval
spectral index (n_s) and cosmic opacity to CMB photons (\tau). Low--l
polarization measures, in principle, can remove it. We perform a likelihood
analysis to see how cosmic variance possibly affects such a problem. We find
that, for a sufficiently low noise level (\sigma_{pix}) and if \tau is not
negligibly low, the degeneracy is greatly reduced, while the residual impact of
cosmic variance on n_s and \tau determinations is under control. On the
contrary, if \sigma_{pix} is too high, cosmic variance effects appear to be
magnified. We apply general results to specific experiments and find that, if
favorable conditions occur, it is possible that a 2--\sigma detection of a
lower limit on \tau is provided by the SPOrt experiment. Furthermore, if the
PLANCK experiment will measure polarization with the expected precision, the
error on low--l harmonics is adequate to determine \tau, without significant
magnification of the cosmic variance. This however indicates that high
sensitivity might be more important than high resolution in \tau
determinations. We also outline that a determination of \tau is critical to
perform detailed analyses on the nature of dark energy and/or on the presence
of primeval gravitational waves.


title:
Properties of the Interstellar Medium and the Propagation of Cosmic Rays
  in the Galaxy

abstract:
  The problem of the origin of cosmic rays in the shocks produced by supernova
explosions at energies below the so called 'knee' (at ~3*10$^6$ GeV) in the
energy spectrum is addressed, with special attention to the propagation of the
particles through the inhomogenious interstellar medium and the need to explain
recent anisotropy results, [1]. It is shown that the fractal character of the
matter density and magnetic field distribution leads to the likelihood of a
substantial increase of spatial fluctuations in the cosmic ray energy spectra.
While the spatial distribution of cosmic rays in the vicinity of their sources
(eg. inside the Galactic disk) does not depend much on the character of
propagation and is largely determined by the distribution of their sources, the
distribution at large distances from the Galactic disk depends strongly on the
character of the propagation. In particular, the fractal character of the ISM
leads to what is known as 'anomalous diffusion' and such diffusion helps us to
understand the formation of Cosmic Ray Halo. Anomalous diffusion allows an
explanation of the recent important result from the Chacaltaya extensive air
shower experiment [1], viz. a Galactic Plane Enhancement of cosmic ray
intensity in the Outer Galaxy, which is otherwise absent for the case of the
so-called 'normal' diffusion. All these effects are for just one reason:
anomalous diffusion emphasizes the role of local phenomena in the formation of
cosmic ray characteristics in our Galaxy and elsewhere.


title: A flattening in the Optical Light Curve of SN 2002ap

abstract:
  We present the $UBVR_cI_c$ broad band optical photometry of the Type Ic
supernova SN 2002ap obtained during 2002 February 06 -- March 23 in the early
decline phases and also later on 2002 15 August. Combining these data with the
published ones, the general light curve development is studied. The time and
luminosity of the peak brightness and the peak width are estimated. There is a
flattening in the optical light curve about 30 days after the $B$ maximum. The
flux decline rates before flattening are 0.127$\pm$0.005, 0.082$\pm$0.001,
0.074$\pm$0.001, 0.062$\pm$0.001 and 0.040$\pm$0.001 mag day$^{-1}$ in $U$,
$B$, $V$, $R_c$ and $I_c$ passbands respectively, while the corresponding
values after flattening are about 0.02 mag day$^{-1}$ in all the passbands. The
maximum brightness of SN 2002ap $M_V = - 17.2$ mag, is comparable to that of
the type Ic 1997ef, but fainter than that of the type Ic hypernova SN 1998bw.
  The peak luminosity indicates an ejection of $\sim$ 0.06 M$_{\odot}$
${}^{56}$Ni mass.
  We also present low-resolution optical spectra obtained during the early
phases.
  The SiII absorption minimum indicates that the photospheric velocity
decreased from $\sim$
  21,360 km s$^{-1}$ to $\sim$ 10,740 km s$^{-1}$ during a period of $\sim$ 6
days.


title:
Shadowing high-dimensional Hamiltonian systems: the gravitational n-body
  problem

abstract:
  A {\it shadow} is an exact solution to a chaotic system of equations that
remains close to a numerically computed solution for a long time, ending in a
{\it glitch}. We study the distribution of shadow durations at low dimension
and how shadow durations scale as dimension increases up to 300 in a slightly
simplified gravitational n-body system. We find that ``softened'' systems are
shadowable for many tens of crossing times even for large n, while in an
``unsoftened'' system each particle encounters glitches independently as a
Poisson process, giving shadow durations that scale as 1/n.


title:
Statistical Methods for Detecting Stellar Occultations by Kuiper Belt
  Objects: the Taiwanese-American Occultation Survey

abstract:
  The Taiwanese-American Occultation Survey (TAOS) will detect objects in the
Kuiper Belt, by measuring the rate of occultations of stars by these objects,
using an array of three to four 50cm wide-field robotic telescopes. Thousands
of stars will be monitored, resulting in hundreds of millions of photometric
measurements per night. To optimize the success of TAOS, we have investigated
various methods of gathering and processing the data and developed statistical
methods for detecting occultations. In this paper we discuss these methods. The
resulting estimated detection efficiencies will be used to guide the choice of
various operational parameters determining the mode of actual observation when
the telescopes come on line and begin routine observations. In particular we
show how real-time detection algorithms may be constructed, taking advantage of
having multiple telescopes. We also discuss a retrospective method for
estimating the rate at which occultations occur.


title: Radiative Transfer in 3D Numerical Simulations

abstract:
  We simulate convection near the solar surface, where the continuum optical
depth is of order unity. Hence, to determine the radiative heating and cooling
in the energy conservation equation, we must solve the radiative transfer
equation (instead of using the diffusion or optically thin cooling
approximations). A method efficient enough to calculate the radiation for
thousands of time steps is needed. We assume LTE and a non-gray opacity grouped
into 4 bins according to strength. We perform a formal solution of the
Feautrier equation along a vertical and four straight, slanted, rays (at four
azimuthal angles which are rotated 15 deg. every time step). We present details
of our method. We also give some results: comparing simulated and observed line
profiles for the Sun, showing the importance of 3D transfer for the structure
of the mean atmosphere and the eigenfrequencies of p-modes, illustrating Stokes
profiles for micropores, and analyzing the effect of radiation on p-mode
asymmetries.


title:
A New Challenge: Bar Formation and Secular Evolution in Lenticular
  Galaxies

abstract:
  To further enhance our understanding on the formation and evolution of bars
in lenticular (S0) galaxies, we are undertaking a detailed photometric and
spectroscopic study on a sample of 22 objects. Here we report the results of a
2D structural analysis on two barred face-on S0's, which indicate that
presently these galaxies do not possess disks. We discuss two possibilities to
explain these surprising results, namely strong secular evolution and bar
formation without disks.


title: Probing Structures of Distant Extrasolar Planets with Microlensing

abstract:
  Planetary companions to the source stars of a caustic-crossing binary
microlensing events can be detected via the deviation from the parent light
curves created when the caustic magnifies the star light reflecting off the
atmosphere or surface of the planets. The magnitude of the deviation is delta_p
e_p rho_p^{-1/2}, where e_p is the fraction of starlight reflected by the
planet and rho_p is the angular radius of the planet in units of angular
Einstein ring radius. Due to the extraordinarily high resolution achieved
during the caustic crossing, the detailed shapes of these perturbations are
sensitive to fine structures on and around the planets. We consider the
signatures of rings, satellites, and atmospheric features on caustic-crossing
microlensing light curves. We find that, for reasonable assumptions, rings
produce deviations of order 10% delta_p, whereas satellites, spots, and zonal
bands produce deviations of order 1% delta_p. We consider the detectability of
these features using current and future telescopes, and find that, with very
large apertures (>30m), ring systems may be detectable, whereas spots,
satellites, and zonal bands will generally be difficult to detect. We also
present a short discussion of the stability of rings around close-in planets,
noting that rings are likely to be lost to Poynting-Robertson drag on a
timescale of order 10^5 years, unless they are composed of large (>>1 cm)
particles, or are stabilized by satellites.


title: Variability-Selected Quasars in MACHO Project Magellanic Cloud Fields

abstract:
  We present 47 spectroscopically-confirmed quasars discovered behind the
Magellanic Clouds identified via photometric variability in the MACHO database.
Thirty-eight quasars lie behind the Large Magellanic Cloud and nine behind the
Small Magellanic Cloud, more than tripling the number of quasars previously
known in this region. The quasars cover the redshift interval 0.2 < z < 2.8 and
apparent mean magnitudes 16.6 < V < 20.1. We discuss the details of quasar
candidate selection based on time variability in the MACHO database and present
results of spectroscopic follow-up observations. Our follow-up detection
efficiency was 20%; the primary contaminants were emission-line Be stars in
Magellanic Clouds. For the 47 quasars discovered behind the Magellanic Clouds
plus an additional 12 objects previously identified in this region, we present
7.5-year MACHO V- and R-band lightcurves with average sampling times of 2-10
days.


title: Observations and Theory of Supernovae

abstract:
  This Resource Letter provides a guide to the literature on the observations
of supernovae and the theory of their explosion mechanisms. Journal articles
and books are cited for the following topics: observations of the spectra,
spectropolarimetry, and light curves of supernovae of various types, theory of
thermonuclear explosions, core collapse, and radioactive decay, applications to
cosmology, and possible connections to gamma-ray bursts.


title:
Spectral Signature of Cosmological Infall of Gas Around the First
  Quasars

abstract:
  Recent observations have shown that, only a billion years after the Big Bang,
the Universe was already lit up by bright quasars fuelled by the infall of gas
onto supermassive black holes. The masses of these early black holes are
inferred from their luminosities to be > 10^9 solar masses, which is a
difficult theoretical challenge to explain. Like nearby quasars, the early
objects could have formed in the central cores of massive host galaxies. The
formation of these hosts could be explained if, like local large galaxies, they
were assembled gravitationally inside massive (> 10^12 solar mass) halos of
dark matter. There has hitherto been no observational evidence for the presence
of these massive hosts or their surrounding halos. Here we show that the cosmic
gas surrounding each halo must respond to its strong gravitational pull, where
absorption by the infalling hydrogen produces a distinct spectral signature.
That signature can be seen in recent data.


title: High Resolution Grating Spectroscopy of GRB 020405 with CHANDRA LETGS

abstract:
  We present high-resolution X-ray spectroscopy of GRB 020405 obtained with the
Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray
Observatory starting 1.68 days after the burst. The spectrum appears
featureless, with no evidence for emission lines, absorption edges, or narrow
radiative recombination continua. The continuum can be fitted by a power law of
photon index Gamma = 1.72 +/- 0.21 and temporal decay index alpha = 1.87 +/-
0.1, with a marginally significant excess column density of cold gas N_{H}=(4.7
+/- 3.7) x 10^{21} cm^{-2} at the redshift of the host galaxy. The absence of
iron lines indicates that the density of nearby surrounding material was
unlikely to be very dense (n < 5 x 10^{12} cm^{-3}) at the time of the Chandra
observation. In the case of recombination following photoionization in an
optically thin medium, most ionic species would be completely stripped at lower
gas densities than this. In the case of a power-law spectrum reflecting off a
``cold'', opaque medium of low density, negligible emission features would be
produced. Alternative to these possible explanations for the lack of emission
features, any X-ray line emission taking place in a dense medium in a ``nearby
reprocessor'' scenario might have been overwhelmed by the bright afterglow
continuum. Although the absence of discrete features does not unambiguously
test for a connection between GRB 020405 and nucleosynthesis, it emphasizes the
need for high-resolution X-ray spectroscopy to determine the exact emission
mechanism responsible for the reported discrete lines in other GRB afterglows.


title: HD 209458 and the Power of the Dark Side

abstract:
  The rich wealth of observational data, and matching theoretical
investigations, of the transiting planet of HD209458 stands in sharp contrast
to systems for which only the radial velocity orbit is known. In this paper, I
summarize the current status of these observations, and motivate a variety of
projects that should be accessible with existing instruments. I describe
observational estimates of the planetary radius, and discuss the relevant
sources of uncertainty. I compare these estimates to those based on theoretical
structural models. This discussion motivates the observational pursuit of three
quantities that could be derived from measurements of the secondary eclipse:
These are the albedo, the temperature, and the orbital eccentricity. I review
the recent detection of the sodium D lines in the planetary atmosphere, and
discuss ongoing work to search for molecular features in the near infrared. I
also outline the use of the Rossiter effect to study the alignment of the orbit
with the stellar equatorial plane, and transit timing to search for additional
objects in the system.


title: Gravitational wave frequencies and energies in hypernovae

abstract:
  A torus develops a state of suspended accretion against a magnetic wall
around a rapidly rotating black hole formed in core-collapse hypernovae. It
hereby emits about 10% of the black hole spin-energy in gravitational radiation
from a finite number of multipole mass moments. We quantify the relation
between the frequency of quadrupole gravitational radiation and the energy
output $E_w$ in torus winds by $f_{gw}\simeq 470{Hz}(E_w/4\times
10^{52}{erg})^{1/2}(7M_\odot/M)^{3/2}$, where $M$ denotes the mass of the black
hole. We propose that $E_w$ irradiates the remnant stellar envelope from
within. We identify $E_w$ with energies $\sim 10^{52}$ erg inferred from X-ray
observations on matter injecta; and the poloidal curvature in the magnetic wall
with the horizon opening angle in baryon poor outflows that power true GRB
energies of $E_\gamma\simeq 3\times 10^{51}$ erg.


title:
A Probable Optical Counterpart for the Isolated Neutron Star RX
  J1308.6+2127

abstract:
  Using a very deep observation with HST/STIS, we have searched for an optical
counterpart to the nearby radio-quiet isolated neutron star RX J1308.6+2127
(RBS 1223). We have identified a single object in the 90% Chandra error circle
that we believe to be the optical counterpart. This object has
$m_{50CCD}=28.56\pm0.13$ mag, which translates approximately to an unabsorbed
flux of $F_{\lambda}=(1.7 \pm 0.3)e-20$ ergs/s/cm^2/A at 5150 A or an
X-ray-to-optical flux ratio of $log(f_X/f_opt)=4.9$. This flux is a factor of
$\approx 5$ above the extrapolation of the black-body fit to the X-ray
spectrum, consistent with the optical spectra of other isolated neutron stars.
Without color information we cannot conclude that this source is indeed the
counterpart of RX J1308.6+2127. If not, then the counterpart must have
$m_{50CCD} > 29.6$ mag, corresponding to a flux that is barely consistent with
the extrapolation of the black-body fit to the X-ray spectrum.


title: The Quiescent Counterpart of the Soft Gamma-ray Repeater SGR 0526-66

abstract:
  It is now commonly believed that Soft gamma-ray repeaters (SGRs) and
Anomalous X-ray pulsars (AXPs) are magnetars -- neutron stars powered by their
magnetic fields. However, what differentiates these two seemingly dissimilar
objects is, at present, unknown. We present Chandra observations of RX
J052600.3-660433, the quiescent X-ray counterpart of SGR 0526-66. Restricting
to a period range around 8-s, the period noted in the afterglow of the burst of
5 March 1979, we find evidence for a similar periodicity in two epochs of data,
obtained 20 months apart, implying a period derivative of $6.6(5)e-11$ s/s
which is similar to the period derivatives of the magnetars. The spectrum is
best fitted by a combination of a black body and a power law. However, the
photon index of the power law component, $\Gamma\sim 3$ -- intermediate to
those of AXPs and SGRs. This continuum of $\Gamma$ leads us to suggest that the
underlying physical parameter which differentiates SGRs from AXPs is manifested
in the power law component. Two decades ago, SGR 0526-66 was a classical SGR
whereas now it behaves like an AXP. Thus it is possible that the same object
cycles between SGR and AXP state. We speculate that the main difference between
AXPs and SGRs is the geometry of the $B$-fields and this geometry is time
dependent. [Abstract truncated]


title: Cosmology on a Mesh

abstract:
  An adaptive multi grid approach to simulating the formation of structure from
collisionless dark matter is described. MLAPM (Multi-Level Adaptive Particle
Mesh) is one of the most efficient serial codes available on the cosmological
'market' today. As part of Swinburne University's role in the development of
the Square Kilometer Array, we are implementing hydrodynamics, feedback, and
radiative transfer within the MLAPM adaptive mesh, in order to simulate
baryonic processes relevant to the interstellar and intergalactic media at high
redshift. We will outline our progress to date in applying the existing MLAPM
to a study of the decay of satellite galaxies within massive host potentials.


title: Deep Near-Infrared Universe Seen in the Subaru Deep Field

abstract:
  The Subaru Deep Field provides the currently deepest K-selected sample of
high-z galaxies (K' = 23.5 at 5 sigma). The SDF counts, colors, and size
distributions in the near-infrared bands are carefully compared with
pure-luminosity-evolution (PLE) as well as CDM-based hierarchical merging (HM)
models. The very flat faint-end slope of the SDF K count indicates that the
bulk (more than 90%) of cosmic background radiation (CBR) in this band is
resolved, even if we take into account every known source of incompleteness.
The integrated flux from the counts is only about a third of reported flux of
the diffuse CBR in the same band, suggesting that a new distinct source of this
missing light may be required. We discovered unusually red objects with colors
of (J-K) >~ 3-4, which are even redder than the known population of EROs, and
difficult to explain by passively evolving elliptical galaxies. A plausible
interpretation, which is the only viable one among those we examined, is that
these are dusty starbursts at high-z (z ~ 3), whose number density is
comparable with that of present-day ellipticals or spheroidal galaxies, as well
as with that of faint submillimeter sources. The photometric redshift
distribution obtained by BVRIz'JK' photometries is also compared with the data,
and the HM model is found to predict too few high-z objects at K' >~ 22 and z
>~ 2; the PLE model with reasonable amount of absorption by dust looks more
consistent with the data. This result is apparently in contradiciton with some
previous ones for shallower observations, and we discuss the origin of this.
These results raise a question for the HM models: how to form massive objects
with starbursts at such high redshifts, which presumably evolve into
present-day elliptical galaxies or bulges?


title: Detection of Carbon Monoxide within the Magellanic Bridge

abstract:
  The Mopra 22m and SEST 15m telescopes have been used to detect and partially
map a region of 12CO(1-0) line emission within the Magellanic Bridge, a region
lying between the Large and Small Magellanic Clouds. The emission appears to be
embedded in a cloud of neutral hydrogen, and is in the vicinity of an IRAS
source. The CO emission region is found to have a 60um/100um flux density ratio
typical for 12CO(1-0) detections within the SMC, although it has a
significantly lower 12CO brightness and velocity width. These suggest that the
observed region is of a low metallicity, supporting earlier findings that the
Magellanic Bridge is not as evolved as the SMC and Magellanic Stream, which are
themselves of a lower metallicity than the Galaxy. Our observations, along with
empirical models based on SMC observations, indicate that the radius of the
detected CO region has an upper limit of ~16 pc. This detection is, to our
knowledge, the first detection of CO emission from the Magellanic Bridge and is
the only direct evidence of star formation through molecular cloud collapse in
this region.


title: Modelling dark energy with quintessence and a cosmological constant

abstract:
  In this talk we present a model of the universe in which dark energy is
modelled explicitely with both a dynamical quintessence field and a
cosmological constant. Our results confirm the possibility of a collapsing
universe (for a given region of the parameter space), which is advantageous for
an adequate formulation of both perturbative quantum field and string theories.
We have also reproduced the measurements of modulus distance from supernovae
with good accuracy.


title: Statistical Shapes of the Highest Pulses in Gamma--Ray Bursts

abstract:
  The statistical shapes of the highest pulse have been studied by aligned
method. A wavelet package analysis technique and a developed pulse--finding
algorithm have been applied to select the highest pulse from burst profiles
observed by BATSE on board CGRO from 1991 April 21 to 1999 January 26. The
results of this work show that the statistical shapes of the highest pulses are
related to energy: the higher the energy, the narrower the pulse. However, the
characteristic structures of the pulses have nothing to do with energy, which
strongly supports the previous conclusion that the temporal profiles in
different channels are self--similar. The characteristic structures of the
pulses can be well described by a model proposed by Norris et al. (1996). The
fitting parameters are: $t_r$=0.12, $t_d$=0.16, $\upsilon =1.09$, the ratio of
$t_r$ to $t_d$ for the pulse is 0.75. The result leads to our conjecture that
the mechanisms of bursts in different gamma-ray bands might be the same. The
shock, either an internal or an external one, producing the pulse, might emit
photons over the four energy channels in the same way.


title: Molecular abundances in carbon-rich circumstellar envelopes

abstract:
  We present a millimetre molecular line survey of seven high mass loss rate
carbon stars in both the northern and southern skies. A total of 196 emission
lines (47 transitions) from 24 molecular species were detected. The observed CO
emission is used to determine mass-loss rates and the physical structure of the
circumstellar envelope, such as the density and temperature structure, using a
detailed radiative transfer analysis. This enables abundances for the remaining
molecular species to be determined. The derived abundances generally vary
between the sources by no more than a factor of five indicating that
circumstellar envelopes around carbon stars with high mass-loss rates have
similar chemical compositions. However, there are some notable exceptions. The
most striking difference between the abundances are reflecting the spread in
the 12C/13C-ratio of about an order of magnitude between the sample stars,
mainly reflecting the results of nucleosynthesis. The abundance of SiO also
shows a variation of more than an order of magnitude between the sources and is
on the average more than an order of magnitude more abundant than predicted
from photospheric chemistry in thermal equilibrium. The over abundance of SiO
is consistent with dynamical modelling of the stellar atmosphere and the inner
parts of the wind where a pulsation-driven shock has passed. This scenario is
possibly further substantiated by the relatively low amount of CS present in
the envelopes. The chemistry occurring in the outer envelope is consistent with
current photochemical models.


title: The s-process branching at 185W

abstract:
  The neutron capture cross section of the unstable nucleus 185W has been
derived from experimental photoactivation data of the inverse reaction
186W(gamma,n)185W. The new result of sigma = (687 +- 110) mbarn confirms the
theoretically predicted neutron capture cross section of 185W of sigma = 700
mbarn at kT = 30 keV. A neutron density in the classical s-process of n_n =
(3.8 +0.9 -0.8} * 1e8 cm-3 is derived from the new data for the 185W branching.
In a stellar s-process model one finds a significant overproduction of the
residual s-only nucleus 186Os.


title:
Effects of halo triaxiality, anisotropy and small scale clumping on WIMP
  direct detection exclusion limits

abstract:
  Weakly Interacting Massive Particle (WIMP) direct detection experiments are
closing in on the region of parameter space where neutralinos may constitute
the Galactic halo dark matter. Numerical simulations and observations of galaxy
halos indicate that the standard Maxwellian halo model is likely to be a poor
approximation to the dark matter distribution. We examine how halo models with
triaxiality and/or velocity anisotropy affect exclusion limits, before
discussing the consequences of the possible survival of small scale clumps.


title:
Can the rapid braking of the white dwarf in AE Aquarii be explained in
  terms of the gravitational wave emitter mechanism?

abstract:
  The spin-down power of the white dwarf in the close binary AE Aquarii
significantly exceeds the bolometric luminosity of the system. The
interpretation of this phenomenon in terms of the gravitational-wave emitter
mechanism has been recently suggested by Choi & Yi. The basic assumption of
their interpretation is that the spatially limited blobs or mounds of the mass
\delta m ~ 10^{-3} M_sun, are present at the magnetic poles of the white dwarf.
We show that the mounds of this mass can be confined by the magnetic field of
the white dwarf only if the dipole magnetic moment of the star exceeds
4x10^{37} G cm^3. Under these conditions, however, the magnetodipole losses of
the white dwarf would exceed the evaluated spin-down power 6 orders of
magnitude. On this basis we discard a possibility that the observed rapid
braking of the white dwarf in AE Aquarii can be explained in terms of the
mechanism proposed by Choi & Yi.


title:
Effect of Rotation on a Developed Turbulent Stratified Convection: the
  Hydrodynamic Helicity, the Alpha-Effect and the Effective Drift Velocity

abstract:
  An effect of rotation on a developed turbulent stratified convection is
studied. Dependencies of the hydrodynamic helicity, the alpha-tensor and the
effective drift velocity of the mean magnetic field on the rate of rotation and
an anisotropy of turbulent convection are found. It is shown that in an
anisotropic turbulent convection the alpha-effect can change its sign depending
on the rate of rotation. Different properties of the effective drift velocity
of the mean magnetic field in a rotating turbulent convection are found, e.g.,
there is a difference in the effective drift velocities for the toroidal and
poloidal magnetic fields; a toroidal effective drift velocity can play a role
of an additional differential rotation. These effects and an effect of a
nonzero divergence of the effective drift velocity of the toroidal magnetic
field on a magnetic dynamo are studied. Astrophysical applications of the
obtained results are discussed.


title: UBVJHKLM photometry and modeling of R Coronae Borealis

abstract:
  We present the results of UBVJHKLM photometry of R CrB spanning the period
from 1976 to 2001. Studies of the optical light curve have shown no evidence of
any stable harmonics in the variations of the stellar emission. In the L band
we found semi-regular oscillations with the two main periods of ~3.3 yr and
11.9 yr and the full amplitude of ~0.8 mag and ~0.6 mag, respectively. The
colors of the warm dust shell (resolved by Ohnaka et al. 2001) are found to be
remarkably stable in contrast to its brightness. This indicates that the inner
radius is a constant, time-independent characteristic of the dust shell. The
observed behavior of the IR light curve is mainly caused by the variation of
the optical thickness of the dust shell within the interval \tau(V)= 0.2-0.4.
Anticorrelated changes of the optical brightness (in particular with P ~ 3.3
yr) have not been found. Their absence suggests that the stellar wind of R CrB
deviates from spherical symmetry. The light curves suggest that the stellar
wind is variable. The variability of the stellar wind and the creation of dust
clouds may be caused by some kind of activity on the stellar surface. With some
time lag, periods of increased mass-loss cause an increase in the dust
formation rate at the inner boundary of the extended dust shell and an increase
in its IR brightness. We have derived the following parameters of the dust
shell (at mean brightness) by radiative transfer modeling: inner dust shell
radius r_in ~ 110 R_*, temperature T_dust(r_in) ~ 860 K, dust density
\rho_dust(r_in) ~ 1.1x10^{-20} g cm^-3, optical depth \tau(V) ~ 0.32 at 0.55
micron, mean dust formation rate [dM/dt]_dust ~ 3.1x10^-9 M_sun / yr, mass-loss
rate [dM/dt]_gas ~ 2.1x10^-7 M_sun / yr, size of the amorphous carbon grains
<(~) 0.01 micron, and B-V ~ -0.28.


title: External Shear in Quadruply Imaged Lens Systems

abstract:
  We use publicly available N-body simulations and semi-analytic models of
galaxy formation to estimate the levels of external shear due to structure near
the lens in gravitational lens systems. We also describe two selection effects,
specific to four-image systems, that enhance the probability of observing
systems to have higher external shear. Ignoring additional contributions from
"cosmic shear" and assuming that lens galaxies are not significantly flattened,
we find that the mean shear at the position of a quadruple lens galaxy is 0.11,
the rms shear is roughly 0.15, and there is roughly a 45% likelihood of
external shear greater than 0.1. This is much larger than previous estimates
and in good agreement with typical measured external shear. The higher shear
primarily stems from the tendency of early-type galaxies, which are the
majority of lenses, to reside in overdense regions.


title: Bispectrum speckle interferometry of the B[e] star MWC 349A

abstract:
  We present the results of bispectrum speckle interferometry of the B[e] star
MWC 349A obtained with the SAO 6m telescope. Our diffraction-limited J-, H-,
and K-band images (resolutions 43--74 mas) suggest the star is surrounded by a
circumstellar disk seen almost edge-on. The observed visibility shape is
consistent with a two-component elliptical disk model, probably corresponding
to the gaseous and dusty components of the disk. We show that the
classification of the object as a pre-main-sequence star or a young planetary
nebula is problematic. An analysis of the uncertainties in the basic parameter
determination lead us to the conclusion that MWC 349A is probably either a B[e]
supergiant or a binary system, in which the B[e]-companion dominates the
observed properties.


title:
Heavy elements in Galactic and Magellanic Cloud HII regions:
  recombination-line versus forbidden-line abundances

abstract:
  We have obtained deep optical, long-slit spectrophotometry of the Galactic
HII regions M 17, NGC 3576 and of the Magellanic Cloud HII regions 30 Doradus,
LMC N11B and SMC N66, recording the optical recombination lines (ORLs) of CII,
NII and OII. Temperature-insensitive ORL C2+/O2+ and N2+/O2 ratios are obtained
for all nebulae except SMC N66. The ORL C2+/O2+ ratios show remarkable
agreement within each galactic system, while also being in agreement with the
corresponding CEL ratios. For all five nebulae, the O2+/H+ abundance derived
from multiple OII ORLs is found to be higher than the corresponding value
derived from the strong [OIII] 4959, 5007A CELs, by factors of 1.8--2.7 for
four of the nebulae. The LMC N11B nebula exhibits a more extreme discrepancy
factor for the O2+ ion, ~5. Thus these HII regions exhibit ORL/CEL abundance
discrepancy factors that are similar to those previously encountered amongst
planetary nebulae.
  Our optical CEL O2+/H+ abundances agree to within 20-30 per cent with
published O2+/H+ abundances that were obtained from observations of infrared
fine-structure lines. Since the low excitation energies of the latter make them
insensitive to variations about typical nebular temperatures, fluctuations in
temperature are ruled out as the cause of the observed ORL/CEL O2+ abundance
discrepancies. We present evidence that the observed OII ORLs from these HII
regions originate from gas of very similar density (<3500 cm-3) to that
emitting the observed heavy-element optical and infrared CELs, ruling out
models that employ high-density ionized inclusions in order to explain the
abundance discrepancy. We consider a scenario whereby much of the heavy-element
ORL emission originates from cold (<=500 K) metal-rich ionized regions.


title: Model Photospheres with Accelerated Lambda Iteration

abstract:
  We address the classical stellar-atmosphere problem and describe our method
of numerical solution in detail. The problem consists of the solution of the
radiation transfer equation under the constraints of hydrostatic, radiative and
statistical equilibrium (non-LTE). We employ the Accelerated Lambda Iteration
(ALI) technique, and use statistical methods to construct non-LTE
metal-line-blanketed model-atmospheres.


title:
Structure and Evolution of Galaxy Clusters: Internal Dynamics of ABCG
  209 at z~0.21

abstract:
  We study the internal dynamics of the rich galaxy cluster ABGC 209 on the
basis of new spectroscopic and photometric data. The distribution in redshift
shows that ABCG 209 is a well isolated peak of 112 detected member galaxies at
z=0.209, characterised by a high value of the line-of-sight velocity
dispersion, sigma_v=1250-1400 Km/s, on the whole observed area (1 Mpc/h from
the cluster center), that leads to a virial mass of M=1.6-2.2x10^15 M_sun
within the virial radius, assuming the dynamical equilibrium. The presence of a
velocity gradient in the velocity field, the elongation in the spatial
distribution of the colour-selected likely cluster members, the elongation of
the X-ray contour levels in the Chandra image, and the elongation of cD galaxy
show that ABCG 209 is characterised by a preferential NW-SE direction. We also
find a significant deviation of the velocity distribution from a Gaussian, and
relevant evidence of substructure and dynamical segregation. All these facts
show that ABCG 209 is a strongly evolving cluster, possibly in an advanced
phase of merging.


title: Neutrino flux predictions for Galactic plerions

abstract:
  We consider a class of plerions that have been detected in the TeV range, and
investigate the possibility that the emission is due to \pi^0 decay. From the
TeV flux we derive what is the expected \nu flux at Earth and find that this is
likely to exceed the detection threshold of the upcoming km^2 neutrino
detectors.


title: Rapid variability of accretion in AM Herculis

abstract:
  We present the last pointed observation of AM Her carried out during the life
of the BeppoSAX satellite. It was bright at the beginning of the observation,
but dropped to the lowest X-ray level ever observed so far. The X-ray emission
during the bright period is consistent with accretion occurring onto the main
pole of the magnetized white dwarf. The rapid change from the active state to
the low deep state indicates a drop by a factor of 17 in the accretion rate and
hence that accretion switched-off. The short timescale (less than one hour) of
this variation still remains a puzzle. Optical photometry acquired
simultaneousy during the low state shows that the white dwarf remains heated,
although a weak emission from the accretion stream could be still present.
Cyclotron radiation, usually dominating the V and R bands, is negligible thus
corroborating the possibility that AM Her was in an off-accretion state. The
X-ray emission during the inactive state is consistent with coronal emission
from the secondary late type star.


title: Effects of Noise on Galaxy Isophotes

abstract:
  The study of shapes of the images of objects is an important issue not only
because it reveals its dynamical state but also it helps to understand the
object's evolutionary history. We discuss a new technique in cosmological image
analysis which is based on a set of non-parametric shape descriptors known as
the Minkowski Functionals (MFs). These functionals are extremely versatile and
under some conditions give a complete description of the geometrical properties
of objects. We believe that MFs could be a useful tool to extract information
about the shapes of galaxies, clusters of galaxies and superclusters. The
information revealed by MFs can be utilized along with the knowledge obtained
from currently popular methods and thus could improve our understanding of the
true shapes of cosmological objects.


title:
The Nuclear Regions of the Seyfert Galaxy NGC 4151 - Parsec-scale HI
  Absorption and a Remarkable Radio Jet

abstract:
  Sensitive high angular and linear resolution radio images of the 240-pc radio
jet in NGC4151, imaged at linear resolutions of 0.3 to 2.6 pc using the VLBA
and phased VLA at 21 cm, are presented and reveal for the first time a faint,
highly collimated jet (diameter <1.4 pc) underlying discrete components, seen
in lower resolution MERLIN and VLA images, that appear to be shock-like
features associated with changes in direction as the jet interacts with small
gas clouds within the central 100 pc of the galaxy. In addition, 21-cm spectral
line imaging of the neutral hydrogen in the nuclear region reveals the spatial
location, distribution and kinematics of the neutral gas detected previously in
a lower resolution MERLIN study. Neutral hydrogen absorption is detected
against component C4W (E+F) as predicted by Mundell et al, but the absorption,
extending over 3 pc, is spatially and kinematically complex on sub-parsec
scales, suggesting the presence of small, dense gas clouds with a wide range of
velocities and column densities. The main absorption component matches that
detected in the MERLIN study and is consistent with absorption through a clumpy
neutral gas layer in the putative obscuring torus, with higher velocity blue-
and red-shifted systems with narrow linewidths also detected across E+F. The
spatial location and distribution of the absorbing gas across component E+F
rules out component E as the location of the AGN (as suggested by Ulvestad et
al.) and, in combination with the well-collimated continuum structures seen in
component D, suggests that component D is the most likely location for the AGN.
We suggest that components C and E are shocks produced in the jet as the plasma
encounters, and is deviated by, dense clouds with diameters smaller than ~1.4
pc. (Abridged)


title: Turbulent Diffusion of Magnetic Fields in Weakly Ionized Gas

abstract:
  The diffusion of uni-directional magnetic fields by two dimensional turbulent
flows in a weakly ionized gas is studied. The fields here are orthogonal to the
plane of fluid motion. This simple model arises in the context of the decay of
the mean magnetic flux to mass ratio in the interstellar medium. When ions are
strongly coupled to neutrals, the transport of a large--scale magnetic field is
driven by both turbulent mixing and nonlinear, ambipolar drift. Using a
standard homogeneous and Gaussian statistical model for turbulence, we show
rigorously that a large-scale magnetic field can decay on at most turbulent
mixing time scales when the field and neutral flow are strongly coupled. There
is no enhancement of the decay rate by ambipolar diffusion. These results
extend the Zeldovich theorem to encompass the regime of two dimensional flows
and orthogonal magnetic fields, recently considered by Zweibel (2002). The
limitation of the strong coupling approximation and its implications are
discussed.


title: The system parameters of DW Ursae Majoris

abstract:
  We present new constraints on the system parameters of the SW Sextantis star
DW Ursae Majoris, based on ultraviolet (UV) eclipse observations with the
Hubble Space Telescope. Our data were obtained during a low state of the
system, in which the UV light was dominated by the hot white dwarf (WD)
primary. Eclipse analysis, using the full Roche lobe geometry, allows us to set
firm limits on the masses and radii of the system components and the distance
between them: 0.67 \leq M_1/M_sun \leq 1.06, 0.008 \leq R_1/R_sun \leq 0.014,
M_2/M_sun > 0.16, R_2/R_sun > 0.28 and a/R_sun > 1.05. For q = M_2/M_1 < 1.5
the inclination must satisfy i > 71 degrees. Using Smith & Dhillon's
mass-period relation for CV secondaries, our estimates for the system
parameters become M_1/M_sun = 0.77 \pm 0.07, R_1/R_sun = 0.012 \pm 0.001,
M_2/M_sun = 0.30 \pm 0.10, R_2/R_sun = 0.34 \pm 0.04, q =0.39 \pm 0.12, i = 82
\pm 4 degrees and a/R_sun = 1.14 \pm 0.06. We have also estimated the spectral
type of the secondary, M3.5 \pm 1.0, and distance to the system, d =930 \pm 160
pc, from time-resolved I- and K-band photometry. Finally, we have repeated
Knigge et al.'s WD model atmosphere fit to the low-state UV spectrum of DW UMa
in order to account for the higher surface gravity indicated by our eclipse
analysis. In this way we obtained a second estimate for the distance, d = 590
\pm 100 pc, which allows us to obtain a second estimate for the spectral type
of the secondary, M7 \pm 2.0. We conclude that the true value for the distance
and spectral type will probably be in between the values obtained by the two
methods.


title:
Sulfur, Chlorine, and Argon Abundances in Planetary Nebulae. III:
  Observations and Results for a Final Sample

abstract:
  This paper is the fourth in a series whose purpose is to study the
interstellar abundances of sulfur, chlorine, and argon in the Galaxy using a
sample of 86 planetary nebulae. Here we present new high-quality
spectrophotometric observations of 20 Galactic planetary nebulae with spectral
coverage from 3700-9600 Angstroms. A major feature of our observations
throughout the entire study has been the inclusion of the near-infrared lines
of [S III] 9069,9532, which allows us to calculate accurate S+2 abundances and
to either improve upon or convincingly confirm results of earlier sulfur
abundance studies. For each of the 20 objects here we calculate ratios of S/O,
Cl/O, and Ar/O and find average values of S/O=1.1E-2+/-1.1E-2,
Cl/O=4.2E-4+/-5.3E-4, and Ar/O=5.7E-3+/-4.3E-3. For six objects we are able to
compare abundances of S+3 calculated directly from available [S IV] 10.5 micron
measurements with those inferred indirectly from the values of the ionization
correction factors for sulfur. In the final paper of the series, we will
compile results from all 86 objects, search for and evaluate trends, and use
chemical evolution models to interpret our results.


title:
Spectroscopic Confirmation of Three Redshift 5.7 Lyman-alpha Emitters
  from the Large Area Lyman Alpha Survey

abstract:
  Narrow-band searches for Lyman alpha emission are an efficient way of
identifying star-forming galaxies at high redshifts. We present Keck telescope
spectra confirming redshifts z = 5.7 for three objects discovered in the Large
Area Lyman Alpha (LALA) survey at Kitt Peak National Observatory.
  All three spectra show strong, narrow emission lines with the asymmetric
profile that is characteristically produced in high redshift Lyman alpha
emitters by preferential HI absorption in the blue wing of the line. These
objects are undetected in deep Bw, V, R, and 6600A narrow-band images from the
NOAO Deep Wide-Field Survey and from LALA, as expected from Lyman break and
Lyman alpha forest absorption at redshift z = 5.7. All three objects show large
equivalent widths (>= 150A in the rest-frame), suggesting at least one of the
following: a top-heavy initial mass function, very low stellar metallicity, or
the presence of an active nucleus. We consider the case for an active nucleus
to be weak in all three objects due to the limited width of the Lyman alpha
emission line (< 500 km/s) and the absence of any other indicator of quasar
activity.
  The three confirmed high redshift objects were among four spectroscopically
observed targets drawn from the sample of 18 candidates presented by Rhoads and
Malhotra (2001). Thus, these spectra support the Lyman alpha emitter population
statistics from our earlier photometric study, which imply little evolution in
number density from z=5.7 to z=4.5 and provide strong evidence that the
reionization redshift is greater than 5.7.


title: Kuiper Belt and Oort Cloud Objects: Microlenses or Stellar Occulters?

abstract:
  The occultation of background stars by foreground Solar system objects, such
as planets and asteroids, has been widely used as an observational probe to
study physical properties associated with the foreground sample. Similarly, the
gravitational microlensing of background stellar sources by foreground mass
concentrations has also been widely used to understand the foreground mass
distribution. Though distinct, these two possibilities present two extreme
cases during a transit; At the edge of the Solar system and beyond, the Kuiper
belt and Oort cloud populations may present interesting foreground samples
where combinations of occultation and lensing, and possibly both during the
same transit, can be observed. To detect these events, wide-field monitoring
campaigns with time sampling intervals of order tenths of seconds are required.
For certain planetary occultation light curves, such as those involving Pluto,
an accounting of the gravitational lensing effect may be necessary when
deriving precise physical properties of the atmosphere through the associated
refraction signal.


title: Anisotropy at the end of the cosmic ray spectrum?

abstract:
  The starburst galaxies M82 and NGC253 have been proposed as the primary
sources of cosmic rays with energies above $10^{18.7}$ eV. For energies $\agt
10^{20.3}$ eV the model predicts strong anisotropies. We calculate the
probabilities that the latter can be due to chance occurrence. For the highest
energy cosmic ray events in this energy region, we find that the observed
directionality has less than 1% probability of occurring due to random
fluctuations. Moreover, during the first 5 years of operation at Auger, the
observation of even half the predicted anisotropy has a probability of less
than $10^{-5}$ to occur by chance fluctuation. Thus, this model can be subject
to test at very small cost to the Auger priors budget and, whatever the outcome
of that test, valuable information on the Galactic magnetic field will be
obtained.