title: RX J1856-3754: Evidence for a Stiff EOS

abstract:
  We have examined the soft X-ray plus optical/UV spectrum of the nearby
isolated neutron star RX J1856-3754, comparing with detailed models of a
thermally emitting surface. Like previous investigators, we find the spectrum
is best fit by a two-temperature blackbody model. In addition, our simulations
constrain the allowed viewing geometry from the observed pulse fraction upper
limits. These simulations show that RX J1856-3754 is very likely to be a normal
young pulsar, with the non-thermal radio beam missing Earth's line of sight.
The SED limits on the model parameter space put a strong constraint on the
star's M/R. At the measured parallax distance, the allowed range for
Mstar=1.5Msun is Rstar=13.7+/-0.6km. Under this interpretation, the EOS is
relatively stiff near nuclear density and the `Quark Star' EOS posited in some
previous studies is strongly excluded. The data also constrain the surface T
distribution over the polar cap.


title: UV-IR Science Prospects with TES Imaging Arrays

abstract:
  We are developing photon-counting cameras employing cryogenic arrays of
energy-resolving TES (Transition Edge Sensor) pixels. These are being tested in
ground-based instruments, but will have their greatest impact when employed on
space platforms, where they can cover the 10micrometer-100nm range with high
time- and moderate energy- resolution. Here we summarize briefly existing
device performance, current directions in array camera development and
anticipated capabilities.


title:
Enhancement of Resonant Thermonuclear Reaction Rates in Extremely Dense
  Stellar Plasmas

abstract:
  The enhancement factor of the resonant thermonuclear reaction rates is
calculated for the extremely dense stellar plasmas in the liquid phase. In
order to calculate the enhancement factor we use the screening potential which
is deduced from the numerical experiment of the classical one-component plasma.
It is found that the enhancement is tremendous for white dwarf densities if the
^{12}C + ^{12}C fusion cross sections show resonant behavior in the
astrophysical energy range. We summarize our numerical results by accurate
analytic fitting formulae.


title: Companions to Young Stars

abstract:
  Brown dwarfs occupy the important region in the mass range between stars and
planets. Their existence, ambigious until only recently, and their properties
give insight into stellar and planetary formation. We present statistical
results of an infrared, coronagraphic survey of young, nearby stars that
includes probable companions to three young G-type stars, Gl 503.2 (G2V), HD
102982 (G3V), and Gl 577 (G5V). The companion to Gl 577 is a possible binary
brown dwarf, according to evolution ary models. A dynamical determination of
the components' masses will be achievable in the near future and be an
excellent test of the predictive ability of the evolutionary models.


title:
Multiscaling and Nonextensivity of Large-scale Structures in the
  Universe

abstract:
  There has been a trend in the past decade to describe the large-scale
structures in the Universe as a (multi)fractal set. However, one of the main
objections raised by the opponents of this approach deals with the transition
to homogeneity. Moreover, they claim there is not enough sampling space to
determine a scaling index which characterizes a (multi)fractal set. In this
work we propose an alternative solution to this problem, using the generalized
thermostatistics formalism. We show that applying the idea of nonextensivity,
intrinsic to this approach, it is possible to derive an expression for the
correlation function, describing the scaling properties of large-scale
structures in the Universe and the transition to homogeneity, which is in good
agreement with observational data.


title: Modelling the non-thermal emission from galaxy clusters

abstract:
  We discuss the relevant processes for the relativistic electrons in the ICM
and the possible mechanisms responsible for the production of these electrons.
We focus on the origin of the radio halos giving some of the observational
diagnostics which may help in discriminating among the different models
proposed so far. Finally, we briefly discuss the discrepancy between the value
of the magnetic field assuming an inverse Compton (IC) origin of the hard X-ray
emission (HXR) and that obtained from Faraday Rotation Measurements (RM).


title: Higher-order moments of the lensing shear and other spin two fields

abstract:
  We present a method for defining higher-order moments of a spin-2 field on
the sky using the transformation properties of these statistics under rotation
and parity. For the three-point function of the cosmic shear we show that the
eight logically possible combinations of the shear in three points can be
divided into two classes, four combinations are even under parity
transformations and four are odd. We compute the expected value of the even
parity ones in the non-linear regime using the halo model and conclude that on
small scales of the four combinations there is one that is expected to carry
most of the signal for triangles close to isosceles. On the other hand, for
collapsed triangles all four combinations are expected to have roughly the same
level of signal although some of the combinations are negative and others
positive. We estimate that a survey of a few square degrees area is enough to
detect this signal above the noise at arc minute scales.


title:
Determination of a negative curvature of the Universe from the
  magnitude-redshift relation of high redshift supernovae

abstract:
  Recent observations of high redshift Supernovae at lower than expected value
of the Hubble constant, widely interpreted as an evidence for accelerating
expansion of the Universe, could alternatively be explained assuming a
hyperbolic Universe with a negative spatial curvature of the order of k = -
1/(2100 Mpc).


title: Radio-Infrared Supernebulae in II Zw 40

abstract:
  We report subarcsecond-resolution VLA and Keck mid-infrared imaging of the
dwarf starburst galaxy II Zw 40. II Zw 40 contains a bright, compact thermal
radio and infrared source with all the characteristics of a collection of dense
HII regions ionized by at least 14,000 O stars. The supernebula is revealed to
be multiple sources within an envelope of weaker emission. The radio emission
is dominated by free-free emission at 2cm, and the spectrum of this emission
appears to be rising. This suggests that the free-free emission is optically
thick at 2cm, and that the individual HII regions are ~1pc in size. This
complex of "supernebulae" dominates the total infrared luminosity of II Zw 40,
although the radio source is less than ~150pc in diameter. Multiple super star
clusters appear to be forming here, the much larger analogues of large Galactic
HII region complexes.


title: Adiabatic Index of Dense Matter and Damping of Neutron Star Pulsations

abstract:
  The adiabatic index Gamma_1 for perturbations of dense matter is studied
under various physical conditions which can prevail in neutron star cores. The
dependence of Gamma_1 on the composition of matter (in particular, on the
presence of hyperons), on the stellar pulsation amplitude, and on the baryon
superfluidity is analyzed. Timescales of damping of stellar pulsations are
estimated at different compositions, temperatures, and pulsation amplitudes.
Damping of pulsations by bulk viscosity in the neutron-star cores can prevent
the stars to pulsate with relative amplitudes > (1-15)% (depending on the
composition of matter).


title: The X-ray Luminosities of HH Objects

abstract:
  The recent detection of X-ray emission from HH 2 and HH 154 with the Chandra
and XMM-Newton satellites (respectively) have opened up an interesting, new
observational possibility in the field of Herbig-Haro objects. In order to be
able to plan further X-ray observations of other HH objects, it is now of
interest to be able to estimate their X-ray luminosities in order to choose
which objects to observe. This paper describes a simple, analytic model for
predicting the X-ray luminosity of a bow shock from the parameters of the flow
(i.e., the size of the bow shock, its velocity, and the pre-shock density). The
accuracy of the analytic model is analyzed through a comparison with the
predictions obtained from axisymmetric, gasdynamic simulations of the leading
working surface of an HH jet. We find that our analytic model reproduces the
observed X-ray luminosities of HH 2 and HH 154, and we propose that HH~80/81 is
a good candidate for future observations with Chandra.


title: A Simple Prediction on the Surface Density of Galaxies at z ~ 6

abstract:
  Systematic surveys are being proposed to discover a significant number of
galaxies at z ~ 6, which is now suggested as the epoch when the reionization
era of the Universe ends. To plan such surveys, we need a reasonable
expectation of the surface density of high redshift galaxies at different flux
limits. Here we present a simple prediction of the surface density of 5.5 < z <
6.5 galaxies in the optical regime, extrapolating from what is already known
about galaxies at z ~ 3. This prediction is consistent with the results of
nearly all known searches for objects at z ~ 6, giving confidence that we may
use it to plan optimal combination of survey depth and sky coverage in
searching for such objects. We suggest that the most efficient strategy with
existing ground-based facilities is to do medium-depth (m_{AB}= 24.0 -- 24.5
mag), wide-field (a couple of square degrees) survey using a wide-field camera
at a 4m-class telescope. As the predicted surface density at this brightness
level is very sensitive to the value of L*, the result of such a survey can be
easily used to constrain the luminosity evolution from z ~ 3 to 6.


title:
VLBI Observations of Water Masers in the Circumstellar Envelope of
  IRC+60169

abstract:
  Water masers around an AGB star, IRC+60169, were observed at four epochs
using the Japanese VLBI networks. The distribution of the maser features is
limited in a thick-shell region, which has inner and outer expansion velocities
of 7 km/s and 14 km/s at radii of 25 mas and 120 mas, respectively. The
distribution of the red-shifted features exhibits a ring-like structure, the
diameter of which is 30 mas, and corresponds to the inner radius of the maser
shell. This implies that dense gas around the star obscures red-shifted
emission. Although a position--radial velocity diagram for the maser features
is consistent with a spherical shell model, the relative proper motions do not
indicate an expansion motion of the shell. A remarkable property has been found
that is a possible periodic change of the alignment pattern of water maser
spots.


title: Multiplicity among chemically peculiar stars II. Cool magnetic Ap stars

abstract:
  We present new orbits for sixteen Ap spectroscopic binaries, four of which
might in fact be Am stars, and give their orbital elements. Four of them are
SB2 systems: HD 5550, HD 22128, HD 56495 and HD 98088. The twelve other stars
are : HD 9996, HD 12288, HD 40711, HD 54908, HD 65339, HD 73709, HD 105680, HD
138426, HD 184471, HD 188854, HD 200405 and HD 216533. Rough estimates of the
individual masses of the components of HD 65339 (53 Cam) are given, combining
our radial velocities with the results of speckle interferometry and with
Hipparcos parallaxes. Considering the mass functions of 74 spectroscopic
binaries from this work and from the literature, we conclude that the
distribution of the mass ratio is the same for cool Ap stars as for normal G
dwarfs. Therefore, the only differences between binaries with normal stars and
those hosting an Ap star lie in the period distribution: except for the case of
HD 200405, all orbital periods are longer than (or equal to) 3 days. A
consequence of this peculiar distribution is a deficit of null eccentricities.
There is no indication that the secondary has a special nature, like e.g. a
white dwarf.


title: The Consequences of assuming m=0 for Global Model-fitting

abstract:
  A recent re-analysis of Whole Earth Telescope observations of GD 358 obtained
in 1990 suggests that asteroseismology of additional DBV white dwarfs can lead
to independent constraints on the important, but poorly determined,
^{12}C(alpha,gamma)^{16}O nuclear reaction rate. Data exist for several other
DBV white dwarfs, but relatively few modes are detected and there is often no
multiplet structure to aid in the identification of the spherical harmonic
indices (l,m). I use a new grid of one million DBV models covering a broad
range of masses, temperatures, and surface helium layer masses to investigate
the consequences of assuming m=0 for global model-fitting. I find that when the
spherical degree is known and the rotation period is of order 1 day, the
model-fitting procedure applied to modes with unknown m-values will still
correctly identify the_families_ of possible solutions, and has a high
probability of identifying the same globally optimal solution found when the
m-value is known.


title: Assessing the X-ray Contribution from Jets in X-ray Binaries

abstract:
  Astrophysical jets exist from the stellar scale up to AGN, and seem to share
common features particularly in the radio. But while AGN jets are known to emit
X-rays, the situation for XRB jets is not so clear. Radio jets have been
resolved in several XRBs in the low/hard state, and it seems likely that some
form of outflow is present whenever this state is achieved. Interestingly, the
flat-to-inverted radio synchrotron emission associated with these outflows
strongly correlates with the X-ray emission in several sources, suggesting that
the jet plasma plays a role at higher frequencies. In this same state, there is
also increasing evidence for a turnover in the IR/optical where the
flat-to-inverted spectrum seems to connect to an optically thin component
extending into the X-rays. We discuss how jet synchrotron emission is likely to
contribute to the X-rays, in addition to inverse Compton up-scattering,
providing a natural explanation for these correlations and the turnover in the
IR/optical band.


title: A search for Symbiotic Stars in the Local Group

abstract:
  The Local Group Census is a narrow- and broad-band survey of all the galaxies
of the Local Group above dec = -30 deg, in progress at the 2.5m Isaac Newton
telescope on La Palma. We discuss here the ability of the survey to detect
symbiotic star candidates in the Local Group, by deriving detection limits in
each of the narrow- and broad-band frames used in the survey, and by estimating
the total number of objects expected in each galaxy. We present two diagnostic
diagrams, based on the adopted photometric filters, to discriminate between
symbiotic stars and other emission-line objects such as planetary nebulae.


title: Pair Annihilation and Radio Emission from Nova Muscae

abstract:
  In the hard X-ray spectra of some X-ray binaries line features around 500 keV
are detected. We interpret these as arising from pair annihilation in
relativistic outflows leading to a significant Doppler shift of the frequencies
of the lines. We show that a small fraction of pairs escaping the annihilation
region may give rise to the radio synchrotron emission observed in Nova Muscae
1991.


title:
Apparent Clustering of Intermediate-redshift Galaxies as a Probe of Dark
  Energy

abstract:
  We show the apparent redshift-space clustering of galaxies in redshift range
of 0.2--0.4 provides surprisingly useful constraints on dark energy component
in the universe, because of the right balance between the density of objects
and the survey depth. We apply Fisher matrix analysis to the the Luminous Red
Galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS), as a concrete example.
Possible degeneracies in the evolution of the equation of state (EOS) and the
other cosmological parameters are clarified.


title: Relative timing of solar flares observed at different wavelengths

abstract:
  The timing of 503 solar flares observed simultaneously in hard X-rays, soft
X-rays and H-alpha is analyzed. We investigated the start and the peak time
differences in different wavelengths, as well as the differences between the
end of the hard X-ray emission and the maximum of the soft X-ray and H-alpha
emission. In more than 90% of the analyzed events, a thermal preheating seen in
soft X-rays is present prior to the impulsive flare phase. On average, the soft
X-ray emission starts 3 min before the hard X-ray and the H-alpha emission. No
correlation between the duration of the preheating phase and the importance of
the subsequent flare is found. Furthermore, the duration of the preheating
phase does not differ for impulsive and gradual flares. For at least half of
the events, the end of the nonthermal emission coincides well with the maximum
of the thermal emission, consistent with the beam-driven evaporation model. On
the other hand, for about 25% of the events there is strong evidence for
prolonged evaporation beyond the end of the hard X-rays. For these events, the
presence of an additional energy transport mechanism, most probably thermal
conduction, seems to play an important role.


title: The Neupert effect in solar flares and implications for coronal heating

abstract:
  Based on simultaneous observations of solar flares in hard and soft X-rays we
studied several aspects of the Neupert effect. About half of 1114 analyzed
events show a timing behavior consistent with the Neupert effect. For these
events, a high correlation between the soft X-ray peak flux and the hard X-ray
fluence is obtained, being indicative of electron-beam-driven evaporation.
However, for about one fourth of the events there is strong evidence for an
additional heating agent other than electron beams. We discuss the relevance of
these findings with respect to Parker's idea of coronal heating by nanoflares.


title:
The Nature of Dark Matter in Elliptical Galaxies: Chandra X-ray
  Observatory Observations of NGC 4636

abstract:
  We determine the total enclosed mass profile from 0.7 to 35 kpc in the
elliptical galaxy NGC 4636 based on the hot interstellar medium temperature
profile measured using the Chandra X-ray Observatory, and other X-ray and
optical data. The total mass increases as radius to the power 1.2 to a good
approximation over this range in radii, attaining a total of 1.5 trillion solar
masses (corresponding to a mass-to-light ratio of 40 solar masses per solar
visual luminosity) at 35 kpc. We find that at least half, and as much as 80%,
of the mass within the optical half-light radius is non-luminous, implying that
NGC 4636 has an exceptionally low baryon fraction. The large inferred dark
matter concentration and central dark matter density, consistent with the upper
end of the range expected for standard cold dark matter halos, imply that
mechanisms proposed to explain low dark matter densities in less massive
galaxies (e.g., self-interacting dark matter, warm dark matter, explosive
feedback) are not effective in elliptical galaxies (and presumably, by
extension, in galaxy clusters). The composite (black hole, stars, and dark
matter) mass distribution has a generally steep slope with no core, consistent
with gravitational lensing studies.


title:
Microquasars in the low/hard state: strong coronae, compact jets, and
  the high frequency variability

abstract:
  We apply a model of magnetically dominated coronae above standard accretion
discs to the low/hard state of galactic black holes. When the disc-corona
coupling is accounted for self-consistently assuming that magneto-rotational
instability is at work in the disc, and that the corona is generated by buoyant
escape of disc magnetic structures, then the model predicts powerful, X-ray
emitting coronae at low accretion rates. A main consequence is discussed: the
possibility that the corona itself is the launching site of powerful, MHD
driven jets/outflows. This depends crucially of the coronal scaleheight.
Finally, we present the first radial profiles of a corona a different accretion
rates, and discuss their implications for high frequency variability.


title: 3-D GRMHD Simulations of Generating Jets

abstract:
  We have performed a first fully 3-D GRMHD simulation with Schwarzschild black
hole with a free falling corona. The initial simulation results show that a jet
is created as in the previous simulations using the axisymmetric geometry with
the mirror symmetry at the equator. However, the time to generate the jet is
longer than in the 2-D axisymmetric simulations. We expect that due to the
additional freedom in the azimuthal dimension without axisymmetry with respect
to the z axis and reflection symmetry with respect to the equatorial plane, the
dynamics of jet formation can be modified. Further simulations are required for
the study of instabilities along the azimuthal direction such as
accretion-eject instability


title: Dark Energy and Matter Evolution from Lensing Tomography

abstract:
  Reconstructed from lensing tomography, the evolution of the dark matter
density field in the well-understood linear regime can provide
model-independent constraints on the growth function of structure and the
evolution of the dark energy density. We examine this potential in the context
that high-redshift cosmology has in the future been fixed by CMB measurements.
We construct sharp tests for the existence of multiple dark matter components
or a dark energy component that is not a cosmological constant. These
functional constraints can be transformed into physically motivated model
parameters. From the growth function, the fraction of the dark matter in a
smooth component, such as a light neutrino, may be constrained to a statistical
precision of sigma(f)= 0.0006 fsky^{-1/2} by a survey covering a fraction of
sky fsky with redshift resolution dz=0.1. For the dark energy, a
parameterization in terms of the present energy density Omega_{DE}, equation of
state w and its redshift derivative w', the constraints correspond to
sigma(w)=0.016 fsky^{-1/2} and a degenerate combination of the other two
parameters. For a fixed Omega_{DE}, sigma(w') = 0.046 fsky^{-1/2}; for
Omega_{DE} marginalized, sigma(w') = 0.069 fsky^{-1/2}.


title: The Internal Extinction Curve of NGC 6302 and its Extraordinary Spectrum

abstract:
  In this paper we present a new method for obtaining the optical
wavelength-dependent reddening function of planetary nebulae, using the nebular
and stellar continuum. The data used was a spectrum of NGC 6302 obtained with a
mean signal to noise of >10^2 A^-1 in the nebular continuum. With such a high
S/N the continuum can be accurately compared with a theoretical model nebular
plus stellar continuum. The nebular electron temperature and density used in
the model are determined using ratios of prominent emission lines. The
reddening function can then be obtained from the ratio of the theoretical and
the observed continuum. We find that for NGC 6302, the visible to IR extinction
law is indistinguishable from `standard' interstellar reddening, but that the
UV extinction curve is much steeper than normal, suggesting that more small
dust grains had been ejected into the nebula by the PN central star. Finally,
using the extinction law that we have determined, we present a complete
de--reddened line list of nearly 600 emission lines, and report on the
detection of the He(2-10) and He(2-8) Raman Features at 4331 A and 4852 A, and
the detection of Raman-Scattered OVI features at 6830 and 7087 AA.


title:
Detection of compact objects by means of gravitational lensing in binary
  systems

abstract:
  We consider the gravitational magnification of light for binary systems
containing two compact objects: white dwarfs, a white dwarf and a neutron star
or a white dwarf and a black hole. Light curves of the flares of the white
dwarf caused by this effect were built in analytical approximations and by
means of numerical calculations. We estimate the probability of the detection
of these events in our Galaxy for different types of binaries and show that
gravitational lensing provides a tool for detecting such systems. We propose to
use the facilities of the Sloan Digital Sky Survey (SDSS) to search for these
flares. It is possible to detect several dozens compact object pairs in such a
programme over 5 years. This programme is apparently the best way to detect
stellar mass black holes with open event horizons.


title:
The Bottom of the Main Sequence and Beyond: Speculations, Calculations,
  Observations, and Discoveries (1958-2002)

abstract:
  In this paper, I briefly review the theoretical and observational work done
since 1958 on the gaseous objects with mass below the H-burning limit. Special
attention is paid to the theory that I developed during the period 1958-1962
for the hydrogen-rich gaseous objects with mass below the minimum main sequence
mass of ~ 0.08 Msun. The three main predictions of this theory (Kumar 1962a;
Kumar 1962b; Kumar 1963a; Kumar 1963b) are discussed. Fragmentation processes
for interstellar clouds are discussed, and it is pointed out that the minimum
mass of a gaseous fragment may be as low as 0.001 Msun. Observational results
obtained since 1995 on the luminous and dark objects of very low mass are
briefly reviewed. Comments are made on the basic nature of the stars and
planets, and it is pointed out that processes of star formation are
fundamentally different from those of planet formation. Arguments are presented
to show that some of the very-low-mass dark companions, discovered since 1995,
were most probably formed by the star formation processes and not by the planet
formation processes.


title: Wide field weak lensing observations of A1835 and A2204

abstract:
  We present mass reconstructions from weak lensing for the galaxy clusters
A1835 and A2204 over 34'x34' fields using data from the ESO/MPG Wide Field
Imager. Using a background galaxy population of 22<R<25.5 we detect the
gravitational shear of A1835 at 8.8 sigma significance, and obtain best-fit
mass profiles of sigma_v=1233^{+66}_{-70} km/s for a singular isothermal sphere
model and r_{200}=1550 h^{-1} kpc, c=2.96 for a `universal' CDM profile. Using
a color-selected background galaxy population of 22<R<25.8 we detect the
gravitational shear of A2204 at 7.2 sigma significance, and obtain best-fit
mass profiles of sigma_v=1035^{+65}_{-71} km/s for a SIS model and r_{200}=1310
h^{-1} km/s, c=6.3 for a `universal' CDM profile. The gravitational shear at
distances greater than 10' is significantly detected for both clusters. The
best fit weak lensing cluster masses agree well with both X-ray and dynamical
mass measurements, although the central concentration of A1835 is much lower in
the weak lensing mass profile than that measured by recent Chandra results. We
suggest that this lower concentration is most likely a combination of
contamination of the 'background' galaxy population with cluster dwarf galaxies
and the effect of a prolate or tri-axial cluster core with the major axis lying
near the plane of the sky. We also detect a number of additional structures at
moderate significance, some of which appear to be sub-haloes associated with
the clusters.


title: Color Confirmation of Asteroid Families

abstract:
  We discuss optical colors of 10,592 asteroids with known orbits selected from
a sample of 58,000 moving objects observed by the Sloan Digital Sky Survey
(SDSS). This is more than ten times larger sample that includes both orbital
parameters and multi-band photometric measurements than previously available.
We confirm that asteroid dynamical families, defined as clusters in orbital
parameter space, also strongly segregate in color space. In particular, we
demonstrate that the three major asteroid families (Eos, Koronis, and Themis),
together with the Vesta family, represent four main asteroid color types. Their
distinctive optical colors indicate that the variations in chemical composition
within a family are much smaller than the compositional differences between
families, and strongly support earlier suggestions that asteroids belonging to
a particular family have a common origin. We estimate that over 90% of
asteroids belong to families.


title: Asteroids Observed by The Sloan Digital Sky Survey

abstract:
  We announce the first public release of the SDSS Moving Object Catalog, with
SDSS observations for 58,117 asteroids. The catalog lists astrometric and
photometric data for moving objects observed prior to Dec 15, 2001, and also
includes orbital elements for 10,592 previously known objects. We analyze the
correlation between the orbital parameters and optical colors for the known
objects, and confirm that asteroid dynamical families, defined as clusters in
orbital parameter space, also strongly segregate in color space. Their
distinctive optical colors indicate that the variations in chemical composition
within a family are much smaller than the compositional differences between
families, and strongly support earlier suggestions that asteroids belonging to
a particular family have a common origin.


title:
Probing Dark Energy with Supernovae: Exploiting Complementarity with the
  Cosmic Microwave Background

abstract:
  A primary goal for cosmology and particle physics over the coming decade will
be to unravel the nature of the dark energy that drives the accelerated
expansion of the Universe. In particular, determination of the
equation-of-state of dark energy, w equivalent p/rho, and its time variation,
dw/dz, will be critical for developing theoretical understanding of the new
physics behind this phenomenon. Type Ia supernovae (SNe) and cosmic microwave
background (CMB) anisotropy are each sensitive to the dark energy
equation-of-state. SNe alone can determine w(z) with some precision, while CMB
anisotropy alone cannot because of a strong degeneracy between the matter
density Omega_M and w. However, we show that the Planck CMB mission can
significantly improve the power of a deep SNe survey to probe w and especially
dw/dz. Because CMB constraints are nearly orthogonal to SNe constraints in the
Omega_M-w plane, for constraining w(z) Planck is more useful than precise
determination of Omega_M. We discuss how the CMB/SNe complementarity impacts
strategies for the redshift distribution of a supernova survey to determine
w(z) and conclude that a well-designed sample should include a substantial
number of supernovae out to redshifts z ~ 2.


title: Evidence for Extremely High Dust Polarization Efficiency in NGC 3184

abstract:
  Recent studies have found the Type II-plateau supernova (SN) 1999gi to be
highly polarized (p_max = 5.8%, where p_max is the highest degree of
polarization measured in the optical bandpass; Leonard & Filippenko 2001) and
minimally reddened (E[B-V] = 0.21 +/- 0.09 mag; Leonard et al. 2002). From
multiple lines of evidence, including the convincing fit of a ``Serkowski''
interstellar polarization (ISP) curve to the continuum polarization shape, we
conclude that the bulk of the observed polarization is likely due to dust along
the line of sight (l-o-s), and is not intrinsic to SN 1999gi. We present new
spectropolarimetric observations of four distant Galactic stars close to the
l-o-s to SN 1999gi (two are within 0.02 degrees), and find that all are null to
within 0.2%, effectively eliminating Galactic dust as the cause of the high
polarization. The high ISP coupled with the low reddening implies an
extraordinarily high polarization efficiency for the dust along this l-o-s in
NGC 3184: ISP / E(B-V) = 31^{+22}_{-9} % mag^{-1}. This is inconsistent with
the empirical Galactic limit (ISP / E[B-V] < 9% mag^{-1}), and represents the
highest polarization efficiency yet confirmed for a single sight line in either
the Milky Way or an external galaxy.


title: Studying Dark Energy with Galaxy Cluster Surveys

abstract:
  Galaxy cluster surveys provide a powerful means of studying the density and
nature of the dark energy. The redshift distribution of detected clusters in a
deep, large solid angle SZE or X-ray survey is highly sensitive to the dark
energy equation of state. Accurate constraints at the 5% level on the dark
energy equation of state require that systematic biases in the mass estimators
must be controlled at better than the ~10% level. Observed regularity in the
cluster population and the availability of multiple, independent mass
estimators suggests these precise measurements are possible. Using
hydrodynamical simulations that include preheating, we show that the level of
preheating required to explain local galaxy cluster structure has a dramatic
effect on X-ray cluster surveys, but only a mild effect on SZE surveys. This
suggests that SZE surveys may be optimal for cosmology while X-ray surveys are
well suited for studies of the thermal history of the intracluster medium.


title: Principles, Progress and Problems in Inflationary Cosmology

abstract:
  Inflationary cosmology has become one of the cornerstones of modern
cosmology. Inflation was the first theory within which it was possible to make
predictions about the structure of the Universe on large scales, based on
causal physics. The development of the inflationary Universe scenario has
opened up a new and extremely promising avenue for connecting fundamental
physics with experiment. This article summarizes the principles of inflationary
cosmology, discusses progress in the field, focusing in particular on the
mechanism by which initial quantum vacuum fluctuations develop into the seeds
for the large-scale structure in the Universe, and highlights the important
unsolved problems of the scenario. The case is made that new input from
fundamental physics is needed in order to solve these problems, and that thus
early Universe cosmology can become the testing ground for trans-Planckian
physics.


title: Far-Infrared Emission from Dust in the ISOPHOT Virgo Cluster Deep Sample

abstract:
  We review the characteristics of the dust continuum emission from normal
galaxies, as revealed by the ISOPHOT Virgo Cluster Deep Survey (Tuffs et al.
2002; Popescu et al. 2002, Popescu & Tuffs 2002b).


title:
PSR B 1706-44 and the SNR G 343.1-2.3 as the remnants of a cavity
  supernova explosion

abstract:
  The possible association of the supernova remnant (SNR) G 343.1-2.3 with the
pulsar PSR B 1706-44 (superposed on the arclike "shell" of the SNR) has been
questioned by some authors on the basis of an inconsistency between the implied
and measured (scintillation) transverse velocities of the pulsar, the absence
of any apparent interaction between the pulsar and the SNR's "shell", and some
other indirect arguments. We suggest, however, that this association could be
real if both objects are the remnants of a supernova (SN) which exploded within
a mushroom-like cavity (created by the SN progenitor wind breaking out of the
parent molecular cloud). This suggestion implies that the actual shape of the
SNR's shell is similar to that of the well-known SNR VRO 42.05.01 and that the
observed bright arc corresponds to the "half" of the SNR located inside the
cloud. We report the discovery in archival radio data of an extended ragged
radio arc to the southeast of the bright arc which we interpret as the "half"
of the SN blast wave expanding in the intercloud medium.


title: The New Galaxy: Signatures of its Formation

abstract:
  The formation and evolution of galaxies is one of the great outstanding
problems of astrophysics. Within the broad context of hierachical structure
formation, we have only a crude picture of how galaxies like our own came into
existence. A detailed physical picture where individual stellar populations can
be associated with (tagged to) elements of the protocloud is far beyond our
current understanding. Important clues have begun to emerge from both the
Galaxy (near-field cosmology) and the high redshift universe (far-field
cosmology). Here we focus on the fossil evidence provided by the Galaxy.
Detailed studies of the Galaxy lie at the core of understanding the complex
processes involved in baryon dissipation. This is a necessary first step
towards achieving a successful theory of galaxy formation.


title:
Observation of Multi-Tev Diffuse Gamma Rays from the Galactic Plane with
  the Tibet Air Shower Array

abstract:
  Data from the Tibet-III air shower array (with energies around 3 TeV) and
from the Tibet-II array (with energies around 10 TeV) have been searched for
diffuse gamma rays from the Galactic plane. These arrays have an angular
resolution of about 0.9 degrees. The sky regions searched are the inner Galaxy,
20 degrees <= l <= 55 degrees, and outer Galaxy, 140 degrees <= l <= 225
degrees, and |b| <= 2 degrees or <= 5 degrees. No significant Galactic plane
gamma-ray excess was observed. The 99% confidence level upper limits for
gamma-ray intensity obtained are (for |b| <= 2 degrees) 1.1 times 10^{-15}
cm^{-2}s^{-1}sr^{-1}MeV^{-1} at 3 TeV and 4.1 times 10^{-17}
cm^{-2}s^{-1}sr^{-1}MeV^{-1} at 10 TeV for the inner Galaxy, and 3.6 times
10^{-16} cm^{-2}s^{-1}sr^{-1}MeV^{-1} at 3 TeV and 1.3 times 10^{-17}
cm^{-2}s^{-1}sr^{-1}MeV^{-1} at 10 TeV for the outer Galaxy, assuming a
differential spectral index of 2.4. The upper limits are significant in the
multi-TeV region when compared to those from Cherenkov telescopes in the lower
energy region and other air shower arrays in the higher energy region; however,
the results are not sufficient to rule out the inverse Compton model with a
source electron spectral index of 2.0.


title: Astro Particle Physics from Space

abstract:
  We review how some open issues on Astro Particle physics can be studied by
space born experiments in a complementary way to what is being done at
underground and accelerators facilities


title:
State transition between high-soft and low-soft states observed in GRS
  1915+105

abstract:
  We present the results of a detailed analysis of RXTE observations which show
an unusual state transition between high-soft and low-soft states in the
microquasar GRS 1915+105. The RXTE pointed observations reveal that these
events appeared as a series of quasi-regular dips when hard X-ray and radio
flux were very low. The X-ray light curve and colour-colour diagram of the
source during these observations are found to be different from any reported so
far. The X-ray spectral and timing properties of the source during these dips
are distinctly different from those seen during the other various dips and low
intensity states seen in this source. There is, however, a remarkable
similarity in the properties during the dip and non-dip regions in these set of
observations. This indicates that the basic accretion disk structure is
similar, but differ only in intensity. We invoke a model, to explain these
observations, in which the viscosity is very close to a critical viscosity and
the shock wave is weak or absent.


title:
The mineral composition and spatial distribution of the dust ejecta of
  NGC 6302

abstract:
  We have analysed the full ISO spectrum of the planetary nebula NGC 6302 in
order to derive the mineralogical composition of the dust in the nebula. We use
an optically thin dust model in combination with laboratory measurements of
cosmic dust analogues. We find two main temperature components at about 100 and
50 K respectively, with distinctly different dust compositions. The warm
component contains an important contribution from dust without strong infrared
resonances. In particular the presence of small warm amorphous silicate grains
can be excluded. The detection of weak PAH bands also points to a peculiar
chemical composition of the dust in this oxygen-rich nebula. The cool dust
component contains the bulk of the mass and shows strong emission from
crystalline silicates, which contain about 10 percent of the mass. In addition,
we identify the 92 micron band with the mineral calcite, and argue that the 60
micron band contains a contribution from the carbonate dolomite. We present the
mass absorption coefficients of six different carbonate minerals. The geometry
of the dust shell around NGC 6302 is studied with mid-infrared images obtained
with TIMMI2. We argue that the cool dust component is present in a
circumstellar dust torus, while the diffuse emission from the warm component
originates from the lobes.


title: The orbit of the double-lined Wolf-Rayet Binary HDE 318016 (= WR98)

abstract:
  We present the discovery of OB type absorption lines superimposed to the
emission line spectrum and the first double-lined orbital elements for the
massive Wolf-Rayet binary HDE 318016 (=WR 98), a spectroscopic binary in a
circular orbit with a period of 47.825 days. The semiamplitudes of the orbital
motion of the emission lines differ from line to line, indicating mass ratios
between 1 and 1.7 for M_WR/M_OB.


title: Magnetic Pinching of Hyperbolic Flux Tubes: I. Basic Estimations

abstract:
  The concept of hyperbolic flux tubes (HFTs) is a generalization of the
concept of separator field lines for coronal magnetic fields with a trivial
magnetic topology. An effective mechanism of a current layer formation in HFTs
is proposed. This mechanism is called magnetic pinching and it is caused by
large-scale shearing motions applied to the photospheric feet of HFTs in a way
as if trying to twist the HFT. It is shown that in the middle of an HFT such
motions produce a hyperbolic flow that causes an exponentially fast growth of
the current density in a thin force-free current layer. The magnetic energy
associated with the current layer that is built up over a few hours is
sufficient for a large flare. Other implications of HFT pinching for solar
flares are discussed as well.


title: Formation and Evolution of Galactic Black Holes

abstract:
  The main requirements for fueling an active galactic nucleus and to form
massive black holes are reviewed. Low-luminosity AGN can be fueled easily from
the local star clusters, near the nucleus, and the various stellar processes
are described. Above a certain luminosity (and therefore accretion rate)
large-scale gas flows from galactic scales are required. These can be driven by
gravity torques of non-axisymmetric perturbations, such as bars, spirals,
galaxy interactions. Observational evidence that these mechanisms are in action
is found for high enough luminosities. It is very frequent that starbursts are
also triggered through the same mechanisms, and the dense nuclear star clusters
formed provide fuel for the AGN over a longer time-scale.
  Secular internal evolution and more violent evolution through interactions
and mergers contribute to grow both a massive black hole and a bulge, and this
could explain the observed proportionality relation between the mass of these
two components.


title:
Ionization history of the cosmic plasma in the light of the recent CBI
  and future PLANCK data

abstract:
  The paper is devoted to the methods of determination of the cosmological
parameters from recent CMB observations. We show that the more complex models
of kinetics of recombination with a few "missing" parameters describing the
recombination process provide better agreement between measured and expected
characteristics of the CMB anisotropy. In particular, we consider the external
sources of the Ly-{alpha} and Ly-{c} radiation and the model with the strong
clustering of baryonic component. These factors can constrain the estimates of
the cosmological parameters usually discussed. We demonstrate also that the
measurements of polarization can improve these estimates and, for the precision
expected for the PLANCK mission, allow to discriminate a wide class of models.


title: Symbiotic Miras vs. Planetary Nebulae in the Near Infrared

abstract:
  While symbiotic Miras and planetary nebulae are hard to distinguish by
optical spectroscopy, their near infrared colors differ. We propose the near
infrared two-color diagram to be an excellent tool to easily distinguish these
two classes of objects.


title: An ASCA Study of the High Luminosity SNR G349.7+0.2

abstract:
  We present ASCA observations of supernova remnant (SNR) G349.7+0.2. The
remnant has an irregular shell morphology and is interacting with a molecular
cloud, evident from the presence of OH(1720 MHz) masers and shocked molecular
gas. The X-ray morphology is consistent with that at radio wavelengths, with a
distinct enhancement in the south. The X-ray emission from the SNR is well
described by a model of a thermal plasma which has yet to reach ionization
equilibrium. The hydrogen column of ~6.0 X 10^{22} cm^{-2} is consistent with
the large distance to the remnant of ~22 kpc estimated from the maser
velocities. We derive an X-ray luminosity of L_x(0.5-10.0 keV)= 1.8 X 10^{37}
d_{22}^2 erg/s, which makes G349.7+0.2 one of the most X-ray luminous
shell-type SNRs known in the Galaxy. The age of the remnant is estimated to be
about 2800 yrs. The ambient density and pressure conditions appear similar to
those inferred for luminous compact SNRs found in starburst regions of other
galaxies, and provides support for the notion that these may be the result of
SNR evolution in the vicinity of dense molecular clouds.


title: No Periodicities in 2dF Redshift Survey Data

abstract:
  We have used the publicly available data from the 2dF Galaxy Redshift Survey
and the 2dF QSO Redshift Survey to test the hypothesis that there is a
periodicity in the redshift distribution of quasi-stellar objects (QSOs) found
projected close to foreground galaxies. These data provide by far the largest
and most homogeneous sample for such a study, yielding 1647 QSO-galaxy pairs.
There is no evidence for a periodicity at the predicted frequency in log(1+z),
or at any other frequency.


title:
Modern Techniques in Galaxy Kinematics: Results from Planetary Nebula
  Spectroscopy

abstract:
  We have observed planetary nebulae (PNe) in several early-type galaxies using
new techniques on 4- to 8-meter-class telescopes. We obtain the first large
data sets (~ 100 velocities each) of PN kinematics in galaxies at > 15 Mpc, and
present some preliminary dynamical results.


title: The Photoionization of a Star-Forming Core in the Trifid Nebula

abstract:
  We have carried out a comprehensive multiwavelength study of Bright-Rimmed
Globule TC2 in the Trifid Nebula using the IRAM~30m telescope, the VLA
centimeter array and the Infrared Space Observatory (ISO). TC2 is one of the
very few globules to exhibit signs of active ongoing star formation while being
photoevaporated. The study of the kinematics shows that TC2 is currently
undergoing an implosion driven by the ionization field. The physical structure
of the molecular core, the Photon-Dominated Region and the ionization front are
characterized. The properties of the PDR are in good agreement with some recent
PDR models. The molecular emission suggests that the star formation process was
probably initiated a few 0.1 Myr ago, in the large burst which led to the
formation of the nebula. The impact of photoionization on the star formation
process appears limited.


title:
Accretion-ejection instability in magnetized disks: Feeding the corona
  with Alfven waves

abstract:
  We present a detailed calculation of the mechanism by which the
Accretion-Ejection Instability can extract accretion energy and angular
momentum from a magnetized disk, and redirect them to its corona. In a disk
threaded by a poloidal magnetic field of the order of equipartition with the
gas pressure, the instability is composed of a spiral wave (analogous to
galactic ones) and a Rossby vortex. The mechanism detailed here describes how
the vortex, twisting the footpoints of field lines threading the disk,
generates Alfven waves propagating to the corona. We find that this is a very
efficient mechanism, providing to the corona (where it could feed a jet or a
wind) a substantial fraction of the accretion energy.


title:
Self-similar solution of fast magnetic reconnection: Semi-analytic study
  of inflow region

abstract:
  An evolutionary process of the fast magnetic reconnection in ``free space''
which is free from any influence of outer circumstance has been studied
semi-analytically, and a self-similarly expanding solution has been obtained.
The semi-analytic solution is consistent with the results of our numerical
simulations performed in our previous paper (see Nitta et al. 2001). This
semi-analytic study confirms the existence of self-similar growth. On the other
hand, the numerical study by time dependent computer simulation clarifies the
stability of the self-similar growth with respect to any MHD mode. These
results confirm the stable self-similar evolution of the fast magnetic
reconnection system.


title: Synchronized SETI - The Case for "Opposition"

abstract:
  If the signals that are being sought in SETI programs do exist but are very
brief, for example because they are produced intermittently to conserve energy,
then it is essential to know when these signals will arrive at the Earth.
Different types of synchronization schemes are possible which vary in the
relative amount of effort which is required by the transmitter and the
receiver. Here the case is made for a scheme which is extremely simple for the
receiver: make observations of a target when it is at maximum angular distance
from the Sun (i.e. "opposition"). This strategy requires the transmitter to
have accurate knowledge of the distance and proper motion of the Sun and the
orbit of the Earth. It is anticipated that within about the next 10 to 20 years
it will be possible to directly detect nearby extra-solar planets of
approximately terrestrial mass. As any extraterrestrial transmitters are
expected to have significantly more advanced technology it is therefore not
unreasonable to expect that these transmitters would be able to detect the
presence of the Earth and measure its orbit at even greater distances. In
addition to the simplicity to the receiver of implementing this strategy it has
the advantage that opposition is typically the time when observations are
easiest to make anyway. A number of all-sky surveys that have already been
performed naturally contain tiny "opposition surveys" within them. A full
all-sky opposition survey would require extensive time to complete with a
single moderate field of view telescope but different types of arrays might be
employed instead including some systems already under construction.


title:
X-ray versus Optical Observations of Active Galactic Nuclei: Evidence
  for Large Grains?

abstract:
  Recently, Maiolino et al. (2001a, A&A, 365, 28) constructed a sample of
active galactic nuclei for which both the reddening E(B-V) and the column
density N_H to the nucleus could be determined. For most of the galaxies in
their sample, they found that E(B-V)/N_H is substantially smaller than for the
diffuse ISM of our Galaxy. They asserted that either the dust-to-gas ratio is
lower than in the Galaxy or that the grains are so large that they do not
extinct or redden efficiently in the optical. We show that there is no
systematic increase in E(B-V) with N_H for the Maiolino et al. (2001a)
galaxies, which suggests that the X-ray absorption and optical extinction occur
in distinct media.
  Maiolino et al. (2001b, A&A, 365, 37) suggested that the observed lines of
sight for the Maiolino et al. (2001a) galaxies pass through the ``torus'' that
obscures the broad line region and nuclear continuum in Seyfert 2 galaxies and
argued that the torus grains are larger than Galactic grains. There is no
reason to believe that the lines of sight for these galaxies pass through the
torus, since the observed column densities are lower than those typically
observed in Seyfert 2 galaxies. We suggest instead that the X-ray absorption
occurs in material located off the torus and/or accretion disk while the
optical extinction occurs in material located beyond the torus. The X-ray
absorbing material could either be dust-free or could contain large grains that
do not extinct efficently in the optical. There is no conclusive evidence that
the grains in active galactic nuclei are systematically larger than those in
the diffuse ISM of our Galaxy.


title:
Relation Between the Thickness of Stellar Disks and the Relative Mass of
  Dark Halo in Galaxies

abstract:
  We consider a thickness of stellar disks of late-type galaxies by analyzing
the R and K_s band photometric profiles for two independent samples of edge-on
galaxies. The main goal is to verify a hypotesis that a thickness of old
stellar disks is related to the relative masses of the spherical and disk
components of galaxies. We confirm that the radial-to-vertical scale length
ratio for galactic disks increases (the disks become thinner) with the
increasing of total mass-to-light ratio of the galaxies, which characterize the
contribution of dark halo to the total mass, and with the decreasing of central
deprojected disk brightness (surface density). Our results are in good
agreement with numerical models of collisionless disks evolved from subcritical
velocity dispersion state to a marginally stable equilibrium state. This
suggests that in most galaxies the vertical stellar velocity dispersion, which
determine the equilibrium disk thickness, is close to the minimum value, that
ensures disk stability. The thinnest edge-on disks appear to be low brightness
galaxies (after deprojection) in which a dark halo mass far exceeds a mass of
the stellar disk.


title: SS433: outflows here and there

abstract:
  We summarize the results of VLBA and global VLBI observations of SS433
between 1995 and 2000. With these observations we resolve the inner jet of the
source and identify an absorption region (~25 AU), the "central radio gap". The
radio gap is caused by free-free absorption of the jet radio emission by a
flattened outflow from the binary system. Radio emission is detected on 100 AU
scales perpendicular to the normal jets ("equatorial emission region";
"equatorial outflow"). At some epochs the emission is smooth but compact
features are frequently detected. We suggest that equatorial outflows may be
common in microquasars.


title: Magnetic field amplification in CDM anisotropic collapse

abstract:
  We use the Zel'dovich approximation to analyse the amplification of magnetic
fields in gravitational collapse of cold dark matter during the mildly
nonlinear regime, and identify two key features. First, the anisotropy of
collapse effectively eliminates one of the magnetic components, confining the
field in the pancake plane. Second, in agreement with recent numerical
simulations, we find that the shear anisotropy can amplify the magnetic field
well beyond the isotropic case. Our results suggest that the magnetic strengths
observed in spiral and disk galaxies today might have originated from seeds
considerably weaker than previous estimates.


title: An Empirical Model for the Radio Emission from Pulsars

abstract:
  A model for slow radio pulsars is proposed which involves the entire
magnetosphere in the production of the observed radio emission. It is argued
that observations of pulsar profiles suggest that a feedback mechanism exists
between the star surface and the null charge surface, requiring particle flow
in both directions. In their flow to and from the surface the particles execute
an azimuthal drift around the magnetic pole, thereby creating a ring of
discrete `emission nodes' close to the surface. Motion of the nodes is observed
as the well-known subpulse `drift', but is interpreted here as a small residual
component of the real particle drift. The nodes can therefore move in either
direction, or even remain stationary. A precise fit is found for the pulsar
PSR0943+10. Azimuthal interactions between different regions of the
magnetosphere depend on the angle between the magnetic and rotation axes and
influence the conal type, as observed. The requirement of intermittent weak
pair-production in an outergap suggests a natural evolutionary link between
radio and gamma-ray pulsars.


title: The Magnetorotational Instability in Core Collapse Supernova Explosions

abstract:
  We investigate the action of the magnetorotational instability (MRI) in the
context of iron-core collapse. Exponential growth of the field on the rotation
time scale by the MRI will dominate the linear growth process of field line
"wrapping" with the same characteristic time. We examine a variety of initial
rotation states, with solid body rotation or a gradient in rotational velocity,
that correspond to models in the literature. A relatively modest value of the
initial rotation, a period of ~ 10 s, will give a very rapidly rotating PNS and
hence strong differential rotation with respect to the infalling matter. We
assume conservation of angular momentum on spherical shells. Results are
discussed for two examples of saturation fields, a fiducial field that
corresponds to Alfven velocity = rotational velocity and a field that
corresponds to the maximum growing mode of the MRI. Modest initial rotation
velocities of the iron core result in sub-Keplerian rotation and a
sub-equipartition magnetic field that nevertheless produce substantial MHD
luminosity and hoop stresses: saturation fields of order 10^{15} - 10^{16} G
develop within 300 msec after bounce with an associated MHD luminosity of about
10^{52} erg/s. Bi-polar flows driven by this MHD power can affect or even cause
the explosions associated with core-collapse supernovae.


title: GRS 1915+105: Ten Years After

abstract:
  It is now ten years since the first microquasar GRS 1915+105 was discovered.
More than six years of observations with RossiXTE have shown a level of
variability never observed in any other X-ray source. Here I try to address
some issues, based on X-ray observations only, that have relevance for
theoretical modeling. First, I ignore these peculiarities and concentrate on
the similarities with other X-ray transients. Then I focus on the peculiar
variability and present a number of obervational facts that need to be
addressed by theoretical models.


title: GX 339-4: back to life

abstract:
  We report preliminary results of a RossiXTE campaign on the 2002 outburst of
the black-hole candidate GX 339-4. We show power density spectra of five
observations during the early phase of the outburst. The first four power
spectra show a smooth transition between a Low State and a Very High State. The
fifth power spectrum resembles a High State, but a strong 6 Hz QPO appears
suddenly within 16 seconds.


title: The 2002 outburst of the microquasar XTE J1550-564

abstract:
  We present results of spectral and timing analysis based on 11 RXTE PCA/HEXTE
observations of the microquasar XTE J1550-564 during its last outburst in
January 2002. The observed behaviour is comparable to most Black-Hole
Candidates in the low/hard state. This is unlike the 1998-99 outburst, when it
showed a much more complex feature, probably because of the higher luminosity.
For each of the 11 observations we extracted energy spectra and power density
spectra, finding typical features of a low/hard state.


title:
Gas Kinematics and the Black Hole Mass at the Center of the Radio Galaxy
  NGC 4335

abstract:
  (abridged) We investigate the kinematics of the central gas disk of the
radio-loud elliptical galaxy NGC 4335, derived from HST/STIS long-slit
spectroscopic observations of Halpha+[NII] along 3 parallel slit positions. The
observed mean velocities are consistent with a rotating thin disk. We model the
gas disk in the customary way. This sets a 3 sigma upper limit of 10^8 Msun on
black hole mass, Mbh. The velocity dispersion at r <0.5'' is in excess of that
predicted by the thin rotating disk model. This does not invalidate the model,
if the excess dispersion is caused by localized turbulent motion in addition to
bulk circular rotation. However, if instead the dispersion is caused by the BH
potential then a mass Mbh ~ 6x10^8 Msun is inferred by modeling the central gas
dispersion as due to an isotropic spherical distribution of collisionless gas
cloudlets. The stellar kinematics for NGC 4335 are derived from a ground-based
(WHT/ISIS) long-slit observation along the galaxy major axis. A two-integral
model of the stellar dynamics yields Mbh >= 3x10^9 Msun. However, there is
reason to believe that this model overestimates Mbh. Reported correlations
between black hole mass and inner stellar velocity dispersion sigma predict Mbh
to be >= 5.4x10^8 Msun in NGC 4335. If our standard thin disk modeling of the
gas kinematics is valid, then NGC 4335 has an unusually low Mbh for its
velocity dispersion. If, on the other hand, this approach is flawed, and
provides an underestimate of Mbh, then black hole masses for other galaxies
derived from HST gas kinematics with the same assumptions should be treated
with caution.


title: Big Bang Nucleosynthesis Constraints on Brane Cosmologies

abstract:
  We examine constraints from Big Bang nucleosynthesis on type II
Randall-Sundrum brane cosmologies with both a dark radiation component and a
quadratic term that depends on the 5-dimensional Planck mass, M_5. Using limits
on the abundances of deuterium and helium-4, we calculate the allowed region in
the M_5-dark radiation plane and derive the precise BBN bound on M_5 alone with
no dark radiation: M_5 > 13 TeV.


title: The Asiago-ESO/RASS QSO Survey II. The Southern Sample

abstract:
  This is the second paper of a series describing the Asiago-ESO/RASS QSO
survey, a project aimed at the construction of an all-sky statistically
well-defined sample of very bright QSOs (B_J < 15). Such a survey is required
to remove the present uncertainties about the properties of the local QSO
population and constitutes an homogeneous database for detailed evolutionary
studies of AGN. We present here the complete Southern Sample, which comprises
243 bright (12.60 < B_J < 15.13) QSO candidates at high galactic latitudes
(|b_{gal}| > 30^{\circ}). The area covered by the survey is 5660 sq. deg.
Spectroscopy for the 137 still unidentified objects has been obtained. The
total number of AGN turns out to be 111, 63 of which are new identifications.
The properties of the selection are discussed. The completeness and the success
rate for this survey at the final stage are 63% and 46%, respectively.


title: Wavefronts, Caustic Sheets, and Caustic Surfing in Gravitational Lensing

abstract:
  Very little attention has been paid to the properties of optical wavefronts
and caustic surfaces due to gravitational lensing. Yet the wavefront-based
point of view is natural and provides insights into the nature of the caustic
surfaces on a gravitationally lensed lightcone. We derive analytically the
basic equations governing the wavefronts, lightcones, caustics on wavefronts,
and caustic surfaces on lightcones in the context of weak-field, thin-screen
gravitational lensing. These equations are all related to the potential of the
lens. In the process, we also show that the standard single-plane gravitational
lensing map extends to a new mapping, which we call a wavefront lensing map.
Unlike the standard lensing map, the Jacobian matrix of a wavefront lensing map
is not symmetric. Our formulas are then applied to caustic ``surfing.'' By
surfing a caustic surface, a space-borne telescope can be fixed on a
gravitationally lensed source to obtain an observation of the source at very
high magnification over an extended time period, revealing structure about the
source that could not otherwise be resolved. Using our analytical expressions
for caustic sheets, we present a scheme for surfing a caustic sheet of a lensed
source in rectilinear motion. Detailed illustrations are also presented of the
possible types of wavefronts and caustic sheets due to nonsingular and singular
elliptical potentials, and singular isothermal spheres, including an example of
caustic surfing for a singular elliptical potential lens.


title:
Nonlinear Effects in Models of the Galaxy: 1. Midplane Stellar Orbits in
  the Presence of 3D Spiral Arms

abstract:
  With the aim of studying the nonlinear stellar and gaseous response to the
gravitational potential of a galaxy such as the Milky Way, we have modeled 3D
galactic spiral arms as a superposition of inhomogeneous oblate spheroids and
added their contribution to an axisymmetric model of the Galactic mass
distribution. Three spiral loci are proposed here, based in different sets of
observations. A comparison of our model with a tight-winding approximation
shows that the self-gravitation of the whole spiral pattern is important in the
middle and outer galactic regions. As a first step to full 3D calculations the
model is suitable for, we have explored the stellar orbital structure in the
midplane of the Galaxy. We present the standard analysis in the pattern
rotating frame, and complement this analysis with orbital information from the
Galactic inertial frame. Prograde and retrograde orbits are defined
unambiguously in the inertial frame, then labeled as such in the Poincar\'e
diagrams of the non-inertial frame. In this manner we found a sharp separatrix
between the two classes of orbits. Chaos is restricted to the prograde orbits,
and its onset occurs for the higher spiral perturbation considered plausible in
our Galaxy.


title: Probing the circumstellar structure of Herbig Ae/Be stars

abstract:
  We present Halpha spectropolarimetry observations of a sample of 23 Herbig
Ae/Be stars. A change in the linear polarisation across Halpha is detected in a
large fraction of the objects, which indicates that the regions around Herbig
stars are flattened (disc-like) on small scales. A second outcome of our study
is that the spectropolarimetric signatures for the Ae stars differ from those
of the Herbig Be stars, with characteristics changing from depolarisation
across Halpha in the Herbig Be stars, to line polarisations in the Ae group.
The frequency of depolarisations detected in the Herbig Be stars (7/12) is
particularly interesting as, by analogy to classical Be stars, it may be the
best evidence to date that the higher mass Herbig stars are surrounded by
flattened structures. For the Herbig Ae stars, 9 out of 11 show a line
polarisation effect that can be understood in terms of a compact Halpha
emission that is itself polarised by a rotating disc-like circumstellar medium.
The spectropolarimetric difference between the Herbig Be and Ae stars may be
the first indication that there is a transition in the Hertzsprung-Russell
Diagram from magnetic accretion at spectral type A to disc accretion at
spectral type B. Alternatively, the interior polarised line emission apparent
in the Ae stars may be masked in the Herbig Be stars due to their higher levels
of Halpha emission.


title: Importance of Supernovae at z>1.5 to Probe Dark Energy

abstract:
  The accelerating expansion of the universe suggests that an unknown component
with strongly negative pressure, called dark energy, currently dominates the
dynamics of the universe. Such a component makes up ~70% of the energy density
of the universe yet has not been predicted by the standard model of particle
physics. The best method for exploring the nature of this dark energy is to map
the recent expansion history, at which Type Ia supernovae have proved adept. We
examine here the depth of survey necessary to provide a precise and
qualitatively complete description of dark energy. Realistic analysis of
parameter degeneracies, allowance for natural time variation of the dark energy
equation of state, and systematic errors in astrophysical observations all
demonstrate the importance of a survey covering the full range 0<z<2 for
revealing the nature of dark energy.


title:
Optimal Weighting Scheme in Redshift-space Power Spectrum Analysis and a
  Prospect for Measuring the Cosmic Equation of State

abstract:
  We develop a useful formula for power spectrum analysis for high and
intermediate redshift galaxy samples, as an extension of the work by Feldman,
Kaiser & Peacock (1994). An optimal weight factor, which minimizes the errors
of the power spectrum estimator, is obtained so that the light-cone effect and
redshift-space distortions are incorporated. Using this formula, we assess the
feasibility of the power spectrum analysis with the luminous red galaxy (LRG)
sample in the Sloan Digital Sky Survey as a probe of the equation of state of
the dark energy. Fisher matrix analysis shows that the LRG sample can be
sensitive to the equation of state around redshift z=0.13. It is also
demonstrated that the LRG sample can constrain the equation of state with
(1-sigma) error of 10% level, if other fundamental cosmological parameters are
well determined independently. For the useful constraint, we point out the
importance of modeling the bias taking the luminosity dependence into account.
We also discuss the optimized strategy to constrain the equation of state using
power spectrum analysis. For a sample with fixed total number of objects, it is
most advantageous to have the sample with the mean number density $10^{-4}
h^3{\rm Mpc}^{-3}$ in the range of the redshift $0.4 \simlt z\simlt 1$.


title: Distribution and Kinematics of O VI in the Galactic Halo

abstract:
  FUSE spectra of 100 extragalactic objects are analyzed to obtain measures of
O VI absorption along paths through the Milky Way thick disk/halo. Strong O VI
absorption over the approximate velocity range from -100 to 100 km/s reveals a
widespread but highly irregular distribution of thick disk O VI, implying the
existence of substantial amounts of hot gas with T ~ 3x10^5 K in the Milky Way
halo. Large irregularities in the distribution of the absorbing gas are found
to be similar over angular scales extending from less than one to 180 degrees,
indicating a considerable amount of small and large scale structure in the gas.
The overall distribution of Galactic O VI is not well described by a
symmetrical plane-parallel layer of patchy O VI absorption. The simplest
departure from such a model that provides a reasonable fit to the observations
is a plane-parallel patchy absorbing layer with a scale height of 2.3 kpc, and
a 0.25 dex excess of O VI in the northern Galactic polar region. The O VI
absorption has a Doppler parameter b = 30 to 99 km/s, with an average value of
60 km/s . Thermal broadening alone cannot explain the large observed profile
widths. The average O VI absorption velocities toward high latitude objects
range from -46 to 82 km/s, with a sample average of 0 km/s and a standard
deviation of 21 km/s. O VI associated with the thick disk moves both toward and
away from the plane with roughly equal frequency. A combination of models
involving the radiative cooling of hot fountain gas, the cooling of supernova
bubbles in the halo, and the turbulent mixing of warm and hot halo gases is
required to explain the presence of O VI and other highly ionized atoms found
in the halo. (abbreviated)


title:
Color Gradients and Surface Brightness Profiles of Galaxies in the
  Hubble Deep Field-North

abstract:
  We fit elliptical isophotes to the Hubble Deep Field-North WFPC-2 and NICMOS
data to study the rest-frame UV_{218}-U_{300} color profiles and rest-frame B
surface brightness profiles of 33 intermediate redshift galaxies (0.5 <= z <=
1.2) with I_{814} < 25 and 50 high redshift galaxies (2.0 <= z <= 3.5) with
H_{160}< 27. From the weighted least-squares fit to the color profiles we find
that, at intermediate redshifts, the galaxies possess negative color gradients
indicating a reddening towards the center of the profile similar to local
samples whereas, at high redshifts, the galaxies possess positive color
gradients. This indicates that star formation is more centrally concentrated in
the distant galaxy sample which differs from the prevalent mode of extended
disk star formation that we observe in the local universe. Additionally, we
find that it is critical to correct for PSF effects when evaluating the surface
brightness profiles since at small scale lengths and faint magnitudes, an
r^{1/4} profile can be smoothed out substantially to become consistent with an
exponential profile. After correcting for PSF effects, we find that at higher
look-back time, the fraction of galaxies possessing exponential profiles have
slightly decreased while the fraction of galaxies possessing r^{1/4} profiles
have slightly increased. Our results also suggest a statistically insignificant
increase in the fraction of peculiar/irregular type galaxies. We compare our
results with recent semi-analytical models which treat galaxy formation and
evolution following the cold dark matter hierarchical framework.


title:
Testing intermediate-age stellar evolution models with VLT photometry of
  LMC clusters. II. Analysis with the Yale models

abstract:
  We present an analysis of CMDs of three intermediate-age LMC clusters, namely
NGC 2173, SL 556 and NGC 2155. The main goal of our project is to investigate
the amount of convective core overshoot necessary to reproduce the CMDs of
relatively metal-poor, intermediate age stellar populations. We conclude that a
moderate amount of overshoot and some fraction of binary stars are essential
for reproducing the observed shapes around the turnoff in the CMD's of all
three clusters: unresolved binary stars fill in the expected core contraction
gap, and make a unique sequence near the gap, which cannot be reproduced by
single stars alone, even with a larger amount of overshoot. From our overall
analysis such as, shape of isochrones, star counts, color distribution, and
synthetic CMD comparisons, we conclude that overshoot ~ 20% of the local
pressure scale height best reproduces the CMD properties of all three clusters.
The best age estimates are 1.5, 2.1 and 2.9 Gyr for NGC 2173, SL 556 and NGC
2155, respectively.


title:
The Physics of Extragalactic Gas: One Argument for a Next Generation
  Space Telescope

abstract:
  Observations of the Galactic ISM have had tremendous impact on our
understanding of the physics of galactic gas and the processes of galaxy
formation. Similar observations at z>2 reveal the neutral baryonic content of
the universe, trace the evolution of metal enrichment, shed light on process of
nucleosynthesis and dust formation, and yield precise measurements of galactic
velocity fields. Owing to the limitations of UV spectroscopy, however,
researchers are unable to examine galactic gas at 0<z<2, an epoch spanning ~80%
of the current universe. To complement the multitude of ongoing programs to
identify and research z<2 galaxies, a next generation space telescope is
essential to investigate the gas which feeds and records the history of galaxy
formation.


title: A solution to the transition phase in classical novae

abstract:
  One century after the discovery of quasi-periodic oscillations in the optical
light curve of Nova GK Per 1901 the cause of the transition phase in a certain
part of the nova population is still unknown. Three years ago we suggested a
solution for this problem and proposed a possible connection between the
transition phase and intermediate polars (IPs). About 10 percent of the
cataclysmic variable population are classified as IPs, which is consistent with
the rarity (about 15 percent) of the transition phase in novae. Recent
observations of three novae seem to support our prediction. The connection is
explained as follows: The nova outburst disrupts the accretion disc only in
IPs. The recovery of the disc, a few weeks-months after the eruption, causes
strong winds that block the radiation from the white dwarf, thus dust is not
destroyed. If the winds are very strong as is probably the case in DQ Her
(perhaps since its spin period is very short) this leads to a dust minimum.


title: Massive Stars in the Arches Cluster

abstract:
  We present and use new spectra and narrow-band images, along with previously
published broad-band images, of stars in the Arches cluster to extract
photometry, astrometry, equivalent width, and velocity information. The data
are interpreted with a wind/atmosphere code to determine stellar temperatures,
luminosities, mass-loss rates, and abundances. We have doubled the number of
known emission-line stars, and we have also made the first spectroscopic
identification of the main sequence for any population in the Galactic Center.
We conclude that the most massive stars are bona-fide Wolf-Rayet (WR) stars and
are some of the most massive stars known, having M_{initial} > 100 Msun, and
prodigious winds, Mdot > 10^{-5} Msun yr^{-1}, that are enriched with helium
and nitrogen; with these identifications, the Arches cluster contains about 5%
of all known WR stars in the Galaxy. We find an upper limit to the velocity
dispersion of 22 kms^{-1}, implying an upper limit to the cluster mass of
7(10^4) Msun within a radius of 0.23 pc; we also estimate the bulk heliocentric
velocity of the cluster to be v_{cluster,odot} approximately +95 kms^{-1}.


title: Rapid Optical Fluctuations in the Black Hole Binary, V4641 Sgr

abstract:
  We report on unprecedented short-term variations detected in the optical flux
from the black hole binary system, V4641 Sgr. Amplitudes of the optical
fluctuations were larger at longer time scales, and surprisingly reached ~60%
around a period of ~10 min. The power spectra of fluctuations are characterized
by a power law. It is the first case in black hole binaries that the optical
emission was revealed to show short-term and large-amplitude variations given
by such a power spectrum. The optical emission from black hole binaries is
generally dominated by the emission from the outer portion of an accretion
disc. The rapid optical fluctuations however indicate that the emission from an
inner accretion region significantly contributes to the optical flux. In this
case, cyclo-synchrotron emission associated with various scales of magnetic
flares is the most promising mechanism for the violently variable optical
emission.


title:
The 3D Structure of the Virgo Cluster Region from Tully-Fisher and HI
  Data

abstract:
  (Abridged) The distances and HI contents of 161 spiral galaxies in the region
of Virgo cluster are used to gain insight into the complicated structure of
this galaxy system. The 3D galaxy distribution has been inferred from quality
distance estimates obtained by averaging distance moduli based upon the TF
relationship taken from eight published datasets previously homogenized.
Previous findings that the spiral distribution is substantially more elongated
along the line-of-sight than in the plane of the sky are confirmed by the
current data. In addition, an important east-west disparity in this effect has
been detected. The overall width-to-depth ratio of the Virgo cluster region is
about 1:4, with the most distant objects concentrated in the western half. The
filamentary structure of the spiral population and its orientation are also
reflected by the HI-deficient objects alone. The HI deficiency pattern shows a
central enhancement arising from galaxies that belong to the Virgo cluster
proper. However, significant gas deficiencies are also detected outside the
main body of the cluster in a probable group of galaxies at line-of-sight
distances 25-30 Mpc, as well as in various foreground galaxies. In the Virgo
region, the HI content of the galaxies then is not a straightforward indicator
of cluster membership.


title: On the Ejection Mechanism of Bullets in SS 433

abstract:
  We discuss plausible mechanisms to produce bullet-like ejecta from the
precessing disk in the SS 433 system. We show that non-steady shocks in the
sub-Keplerian accretion flow can provide the basic timescale of the ejection
interval while the magnetic rubber-band effect of the toroidal flux tubes in
this disk can yield flaring events.


title:
The Planetary Nebulae Spectrograph: the green light for Galaxy
  Kinematics

abstract:
  Planetary nebulae are now well established as probes of galaxy dynamics and
as standard candles in distance determinations. Motivated by the need to
improve the efficiency of planetary nebulae searches and the speed with which
their radial velocities are determined, a dedicated instrument - the Planetary
Nebulae Spectrograph or PN.S - has been designed and commissioned at the 4.2m
William Herschel Telescope. The high optical efficiency of the spectrograph
results in the detection of typically ~ 150 PN in galaxies at the distance of
the Virgo cluster in one night of observations. In the same observation the
radial velocities are obtained with an accuracy of ~ 20 km/s


title:
Mass segregation in rich clusters in the Large Magellanic Cloud - III.
  Implications for the initial mass function

abstract:
  The distribution of core radii of rich clusters in the Large Magellanic Cloud
(LMC) systematically increases in both upper limit and spread with increasing
cluster age. Cluster-to-cluster variations in the stellar initial mass function
(IMF) have been suggested as an explanation. We discuss the implications of the
observed degree of mass segregation in our sample clusters for the shape of the
initial mass function.
  Our results are based on Hubble Space Telescope/WFPC2 observations of six
rich star clusters in the LMC, selected to include three pairs of clusters of
similar age, metallicity, and distance from the LMC centre, and exhibiting a
large spread in core radii between the clusters in each pair.
  All clusters show clear evidence of mass segregation: (i) their luminosity
function slopes steepen with increasing cluster radius, and (ii) the brighter
stars are characterized by smaller core radii. For all sample clusters, both
the slope of the luminosity function in the cluster centres and the degree of
mass segregation are similar to each other, within observational errors of a
few tenths of power-law slope fits to the data. This implies that their INITIAL
mass functions must have been very similar, down to ~0.8 - 1.0 M(sun).
  We therefore rule out variations in the IMF of the individual sample clusters
as the main driver of the increasing spread of cluster core radii with cluster
age.


title:
Facility class Rayleigh beacon AO system for the 4.2m William Herschel
  Telescope

abstract:
  A rationale is presented for the use of a relatively low-altitude Rayleigh
Laser Guide Star to provide partial adaptive optics correction across a large
fraction of the sky on the 4.2m William Herschel Telescope. The scientific
motivation is highlighted and supported by model calculations. An overview the
technical implementation of the system is presented.


title: COMPTEL upper limits for the 56Co gamma-ray emission from SN1998bu

abstract:
  Supernova 1998bu in the galaxy M96 was observed by COMPTEL for a total of 88
days starting 17 days after the explosion. We searched for a signal in the 847
keV and 1238 keV lines of radioactive 56Co from this type Ia supernova. Using
several different analysis methods, we did not detect SN1998bu. Our
measurements should have been sensitive enough to detect 60Co gamma-rays as
predicted from supernova models. Our 2-sigma flux limit is 2.3 10^{-5} photons
cm^{-2} s^{-1}; this would correspond to 0.35 solar mass of ejected 56Ni, if
SN1998bu were at a distance of 11.3 Mpc and transparent to MeV gamma rays for
the period of our measurements. We discuss our measurements in the context of
common supernova models, and conclude disfavoring a supernova event with large
mixing and major parts of the freshly-generated radioactivity in outer layers.


title:
The Large-Scale Structure of the X-ray Background and its Cosmological
  Implications

abstract:
  A careful analysis of the HEAO1 A2 2-10 keV full-sky map of the X-ray
background (XRB) reveals clustering on the scale of several degrees. After
removing the contribution due to beam smearing, the intrinsic clustering of the
background is found to be consistent with an auto-correlation function of the
form (3.6 +- 0.9) x 10^{-4} theta^{-1} where theta is measured in degrees. If
current AGN models of the hard XRB are reasonable and the cosmological
constant-cold dark matter cosmology is correct, this clustering implies an
X-ray bias factor of b_X ~ 2. Combined with the absence of a correlation
between the XRB and the cosmic microwave background, this clustering can be
used to limit the presence of an integrated Sachs-Wolfe (ISW) effect and
thereby to constrain the value of the cosmological constant, Omega_Lambda <
0.60 (95 % C.L.). This constraint is inconsistent with much of the parameter
space currently favored by other observations. Finally, we marginally detect
the dipole moment of the diffuse XRB and find it to be consistent with the
dipole due to our motion with respect to the mean rest frame of the XRB. The
limit on the amplitude of any intrinsic dipole is delta I / I < 5 x 10^{-3} at
the 95 % C.L. When compared to the local bulk velocity, this limit implies a
constraint on the matter density of the universe of Omega_m^{0.6}/b_X(0) >
0.24.


title: University of St.Andrews Open Cluster Survey for Hot Jupiters

abstract:
  We are using the Isaac Newton Telescope Wide Field Camera to survey open
cluster fields for transiting hot Jupiter planets. Clusters were selected on
the basis of visibility, richness of stars, age and metallicity. Observations
of NGC 6819, 6940 and 7789 began in 1999 and continued in 2000. We have
developed an effective matched-filter transit-detection algorithm which has
proved its ability to identify very low amplitude eclipse events in real data.
Here we present our results for NGC 6819. We have identified 7 candidates
showing transit-like events. Colour information suggests that most of the
companion bodies are likely to be very-low-mass stars or brown dwarfs,
intrinsically interesting objects in their own right.


title: Dusty Rings: Signposts of Recent Planet Formation

abstract:
  Many nearby stars are surrounded by a bright ring or disk of cold dust. Our
calculations show that these disks and rings of dust are signposts of recent
planet formation. Bright rings appear because dust associated with the
formation of a planet absorbs and scatters light from the central star. The
calculations explain the rings observed so far and predict that all nascent
solar systems have dusty rings.


title: Observational Implications of a Plerionic Environment for GRBs

abstract:
  We consider GRBs that occur inside pulsar wind bubbles (PWBs), in the context
of the supranova model, where initially a supernova explosion takes place,
leaving behind a supra-massive neutron star (SMNS), which eventually loses its
rotational energy and collapses to a black hole, triggering a GRB explosion.
The most natural mechanism by which the SMNS can lose its rotational energy is
through a strong pulsar type wind, between the supernova and the GRB events,
which is expected to create a PWB. We analyze in some detail the observational
implications of such a plerionic environment on the afterglow (AG) and prompt
GRB emissions, and the prospect for direct detection of the plerion emission.
We find that for a simple spherical model, GRBs with iron lines detected in the
X-ray AG should not have a detectable radio afterglow, and should have small
jet break times and non-relativistic transition times, in disagreement with
observations for some of the GRBs with X-ray lines. These discrepancies with
the observations may be reconciled by resorting to a non-spherical geometry,
where the PWB is elongated along the polar axis. We find that lack of detection
of the plerion emission provides interesting constraints on the model
parameters. Finally, we predict that the inverse Compton upscattering of the
PWB photons by the relativistic electrons of the AG (external Compton, EC)
should lead to high energy emission during the early AG that might explain the
GeV photons detected by EGRET for a few GRBs, and should be detectable by
future missions such as GLAST.


title: Joint Analysis of CMB Temperature and Polarization Power Spectra

abstract:
  This paper has been withdrawn. It was an early draft submitted prematurely in
error. A complete version is to be submitted shortly.


title: The X-ray Reflectors in the Nucleus of the Seyfert Galaxy NGC 1068

abstract:
  (abridged) Based on observations of the Seyfert nucleus in NGC1068 with ASCA,
RXTE and BeppoSAX, we report the discovery of a flare (increase in flux by a
factor of ~1.6) in the 6.7 keV Fe K line component between observations
obtained 4 months apart, with no significant change in the other (6.21, 6.4,
and 6.97 keV) Fe K_alpha line components. During this time, the continuum flux
decreased by ~20%. The RXTE spectrum requires an Fe K absorption edge near 8.6
keV (Fe XXIII - XXV). The spectral data indicate that the 2-10 keV continuum
emission is dominated (~2/3 of the luminosity) by reflection from a previously
unidentified region of warm, ionized gas located <~ 0.2 pc from the AGN. The
remaining ~1/3 of the observed X-ray emission is reflected from optically
thick, neutral gas. The inferred properties of the warm reflector (WR) are:
size (diameter) <~0.2 pc, gas density n >~ 10^{5.5} /cm3, ionization parameter
xi approx 10^{3.5} erg cm/s, and covering fraction 0.003 (L_0/10^{43.5}
erg/s)^{-1} < (Omega/4 pi) < 0.024 (L_0/10^{43.5})^{-1}, where L_0 is the
intrinsic 2-10 keV X-ray luminosity of the AGN. We suggest that the WR gas is
the source of the (variable) 6.7 keV Fe line emission, and the 6.97 keV Fe line
emission. The 6.7 keV line flare is assumed to be due to an increase in the
emissivity of the WR gas from a decrease (by 20-30%) in L_0. The properties of
the WR are most consistent with an intrinsically X-ray weak AGN with L_0 approx
10^{43.0} erg/s. The optical and UV emission that scatters from the WR into our
line of sight is required to suffer strong extinction, which can be reconciled
if the line-of-sight skims the outer surface of the torus. Thermal
bremsstrahlung radio emission from the WR may be detectable in VLBA radio maps
of the NGC 1068 nucleus.


title:
Data reduction and astrometry strategies for wide-field images: an
  application to the Capodimonte Deep Field

abstract:
  The Capodimonte Deep Field (OACDF) is a multi-colour imaging survey on two
0.5x0.5 square degree fields performed in the BVRI bands and in six medium-band
filters (700 - 900 nm) with the Wide Field Imager (WFI) at the ESO 2.2 m
telescope at La Silla, Chile. In this contribution the adopted strategies for
the OACDF data reduction are discussed. Preliminary scientific results of the
survey are also presented.


title: Evolution of Galaxy Morphology

abstract:
  A strictly empirical review is given of presently available data on the
evolution of galaxy morphology. From HST observations of distant galaxies and
ground-based observations of nearby ones observed at the same rest-frame
wavelength it is found that late-type (Sbc-Sc) galaxies evolve more rapidly
with increasing redshift than do early-type (E-Sa-Sab) galaxies. Furthermore
the fraction of peculiar objects, that cannot be shoehorned into the Hubble
tuning fork classification scheme, increases rapidly with redshift.
Unexpectedly it is found that, over a wide range of densities, the fraction of
barred galaxies is independent of environment. However, this fraction of barred
galaxies appears to decline rapidly with increasing redshift.


title: On the Minimum Energy Configuration of a Rotating Barotropic Fluid

abstract:
  In a recent paper (astro-ph/0207561, posted on July 25, 2002), Fromang &
Balbus state that ``a uniformly rotating barotropic fluid in an external
potential attains a true energy minimum if and only if the rotation profile is
everywhere subsonic. If regions of supersonic rotation are present, fluid
variations exist that could take the system to states of lower energy.'' We
present a simple counter-example which demonstrates that the stablity criterion
presented by Fromang & Balbus is incorrect.


title:
The ARAUCARIA project: Deep near-infrared survey of nearby galaxies. I.
  The distance to the Large Magellanic Cloud from K-band photometry of red
  clump stars

abstract:
  We have obtained deep imaging in the near-infrared J and K bands for 2 nearby
fields in the bar of the LMC with the ESO NTT telescope, under exquisite seeing
conditions. The K, J-K color-magnitude diagrams constructed from these data are
of outstanding photometric quality and reveal the presence of several hundreds
of red clump stars. Using the calibration of Alves for the K-band absolute
magnitude of Hipparcos-observed red clump stars in the solar neigbourhood we
derive a distance modulus to our observed LMC fields of 18.487 mag. Applying a
correction for the tilt of the LMC bar with respect to the line of sight
according to the geometrical model of van der Marel et al., the corresponding
LMC barycenter distance is 18.501 mag. If we adopt a K-band population
correction of -0.03 mag, as done by Alves et al. 2002, to account for the
difference in age and metallicity between the solar neighborhood and LMC red
clump star populations, we obtain an LMC barycenter distance modulus of 18.471
mag from our data. This is in excellent agreement with the result of Alves et
al., and of another very recent study of Sarajedini et al. (2002) obtained from
K-band photometry. However, we emphasize that current model predictions about
the uncertainties of population corrections seem to indicate that errors up to
about 0.12 mag may be possible, probably in any photometric band. Therefore,
work must continue to tighten the constraints on these corrections. We also
determine the mean red clump star magnitude in our LMC fields in the J band,
which could be a useful alternative to the K band should future work reveal
that population effect corrections for red clump stars in the J band are
smaller, or more reliably determined than those for the K band.


title:
SN 1986J VLBI. The Evolution and Deceleration of the Complex Source and
  a Search for a Pulsar Nebula

abstract:
  We report on VLBI observations of supernova 1986J in the spiral galaxy NGC
891 at two new epochs, 1990 July and 1999 February, t=7.4 and 15.9 yr after the
explosion, and on a comprehensive analysis of these and earlier observations
from t~4 yr after the explosion date, which we estimate to be 1983.2 +/- 1.1.
The source is a shell or composite, and continues to show a complex morphology
with large brightness modulations along the ridge and with protrusions. The
supernova is moderately to strongly decelerated. The average outer radius
expands as t^(0.71 +/- 0.11), and the expansion velocity has slowed to 6000
km/s at t=15.9 yr from an extrapolated 20,000 km/s at t=0.25 yr. The structure
changes significantly with time, showing that the evolution is not
self-similar. The shell structure is best visible at the latest epoch, when the
protrusions have diminished somewhat in prominence and a new, compact component
has appeared. The radio spectrum shows a clear inversion above 10 GHz. This
might be related to a pulsar nebula becoming visible through the debris of the
explosion. The radio flux density between 1.5 and 23 GHz decreases strongly
with time, with the flux density proportional to t^(-2.94 +/- 0.24) between
t~15 to 19 yr. This decrease is much more rapid than that found in earlier
measurements up to t~6 yr.


title: Hot White Dwarf Donors in Ultracompact X-Ray Binaries

abstract:
  The discovery of two accreting millisecond X-ray pulsars in binaries with 43
minute orbital periods allows for a new probe of the donor's structure. For XTE
J1751-305, only a hot white dwarf (WD) can fill the Roche Lobe. A cold He WD is
a possible solution for XTE J0929-314, though I will show that evolutionary
arguments make a hot WD more likely. In addition to being larger than the T=0
models, these finite entropy, low-mass (<0.03 solar masses) WDs have a minimum
mass for a fixed core temperature. If they remain hot as they lose mass and
expand, they can ``evaporate'' to leave an isolated millisecond radio pulsar.
They also adiabatically expand upon mass loss at a rate faster than the growth
of the Roche radius if the angular momentum deposited in the disk is not
returned to the donor. If the timescale of the resulting runaway mass transfer
is shorter than the viscous timescale in the outer disk, then the mass transfer
instability of Ruderman and Shaham for He WDs would be realized. However, my
estimates of these timescales still makes the instability unlikely for
adiabatic responses. I close by noting the possible impact of finite T WDs on
our understanding of AM CVn binaries.


title:
Interferometric Observations of the Nuclear Region of Arp220 at
  Submillimeter Wavelengths

abstract:
  We report the first submillimeter interferometric observations of an
ultraluminous infrared galaxy. We observed Arp220 in the CO J=3-2 line and
342GHz continuum with the single baseline CSO-JCMT interferometer consisting of
the Caltech Submillimeter Observatory (CSO) and the James Clerk Maxwell
Telescope (JCMT). Models were fit to the measured visibilities to constrain the
structure of the source. The morphologies of the CO J=3-2 line and 342GHz
continuum emission are similar to those seen in published maps at 230 and
110GHz. We clearly detect a binary source separated by about 1 arcsec in the
east-west direction in the 342GHz continuum. The CO J=3-2 visibility
amplitudes, however, indicate a more complicated structure, with evidence for a
compact binary at some velocities and rather more extended structure at others.
Less than 30% of the total CO J=3-2 emission is detected by the interferometer,
which implies the presence of significant quantities of extended gas. We also
obtained single-dish CO J=2-1, CO J=3-2 and HCN J=4-3 spectra. The HCN J=4-3
spectrum, unlike the CO spectra, is dominated by a single redshifted peak. The
HCN J=4-3/CO J=3-2, HCN J=4-3/HCN J=1-0 and CO J=3-2/2-1 line ratios are larger
in the redshifted (eastern) source, which suggests that the two sources may
have different physical conditions. This result might be explained by the
presence of an intense starburst that has begun to deplete or disperse the
densest gas in the western source, while the eastern source harbors undispersed
high density gas.


title:
XMM-Newton Spectroscopy of the Accretion-Driven Millisecond X-ray Pulsar
  XTE J1751-305 in Outburst

abstract:
  We present an analysis of the first high-resolution spectra measured from an
accretion-driven millisecond X-ray pulsar in outburst. We observed XTE
J1751-305 with XMM-Newton on 2002 April 7 for approximately 35 ksec. Using a
simple absorbed blackbody plus power-law model, we measure an unabsorbed flux
of (6.6 +/- 0.1) * 10^(-10) erg/cm^2/s (0.5--10.0 keV). A hard power-law
component (Gamma = 1.44 +/- 0.01) contributes 83% of the unabsorbed flux in the
0.5-10.0 keV band, but a blackbody component (kT = 1.05 +/- 0.01 keV) is
required. We find no clear evidence for narrow or broad emission or absorption
lines in the time-averaged spectra, and the sensitivity of this observation has
allowed us to set constraining upper-limits on the strength of important
features. The lack of line features is at odds with spectra measured from some
other X-ray binaries which share some similarities with XTE J1751-305. We
discuss the implications of these findings on the accretion flow geometry in
XTE J1751-305.