title:
The ultraviolet extragalactic background light: dust extinction and the
  evolution of the cosmic star formation rate from z=0 to 0.6

abstract:
  We show that the accumulated light of galaxies in the ultraviolet can be
evaluated from their luminosity density as a function of the evolution of the
cosmic star formation rate and dust extinction properties. Constraints on the
evolution rate are expected in future. Data available at the moment are
consistent with an evolution rate at low z steeper than (1+z)^(3.5). A
shallower rate remains possible if the luminosity-weighted dust extinction at
2000 A, as suggested by some data, is lower than about 1.2.


title: Keys to Cosmology - Clusters of Galaxies

abstract:
  We review several aspects of clusters of galaxies and their application to
cosmology. We present first results of numerical simulations of the dynamics of
the intra-cluster gas and of different interaction processes between cluster
galaxies and the intra-cluster gas. In particular metallicity maps are very
useful to determine the importance of the different interaction processes. Also
mass determination methods and possible sources for uncertainties in the
measurements are shown.


title: Evolution of Hard X-Ray Spectra Along the Branches in Cir X-1

abstract:
  Using the data from the PCA and HEXTE on board the RXTE satellite, we
investigate the evolution of the 3-200 keV spectra of the peculiar low mass
X-ray binary (LMXB) Cir X-1 along the branches on its hardness-intensity
diagram (HID) from the vertical horizontal branch (VHB), through the horizontal
horizontal branch (HHB) and normal branch (NB), to the flaring branch (FB). We
detect a power-law hard component in the spectra. It is found that the derived
photon indices ($\Gamma$) of the power-law hard component are correlated with
the position on the HID. The power-law component dominates the X-ray emission
of Cir X-1 in the energy band higher than $\sim 20$ keV. The fluxes of the
power-law component are compared with those of the bremsstrahlung component in
the spectra. A possible origin of the power-law hard component is discussed.


title: Fundamental physics in space: a Quantum-Gravity perspective

abstract:
  I consider the possibility that space experiments be used to search for
quantum properties of spacetime. On the basis of recent quantum-gravity
results, I argue that insight on some quantum properties of spacetime can be
obtained with experiments planned for the International Space Station, such as
AMS and EUSO, and with satellite gamma-ray telescopes, such as GLAST.


title: Is planetary migration inevitable?

abstract:
  According to current theories, tidal interactions between a disk and an
embedded planet may lead to the rapid migration of the protoplanet on a
timescale shorter than the disk lifetime or estimated planetary formation
timescales. Therefore, planets can form only if there is a mechanism to hold at
least some of the cores back on their way in. Once a giant planet has
assembled, there also has to be a mechanism to prevent it from migrating down
to the disk center. This paper reviews the different mechanisms that have been
proposed to stop or slow down migration.


title:
Population synthesis modeling of the X-ray background with genetic
  algorithm - based optimization method

abstract:
  We present population synthesis modeling of the X-ray background with genetic
algorithm - based optimization method. In our models the best fit could be
achieved for lower values of high-energy exponential cut-off (~ 170 keV) and
larger amount of the highly obscured (log N_H=25.5) AGNs.


title: ROTSE-III Observations of the Early Afterglow From GRB 030329

abstract:
  Using two identical telescopes at widely separated longitudes, the ROTSE-III
network observed decaying emission from the remarkably bright afterglow of GRB
030329. In this report we present observations covering 56% of the period from
1.5-47 hours after the burst. We find that the light curve is piecewise
consistent with a powerlaw decay. When the ROTSE-III data are combined with
data reported by other groups, there is evidence for five breaks within the
first 20 hours after the burst. Between two of those breaks, observations from
15.9-17.1 h after the burst at 1-s time resolution with McDonald Observatory's
2.1-m telescope reveal no evidence for fluctuations or deviations from a simple
power law. Multiple breaks may indicate complex structure in the jet. There are
also two unambiguous episodes at 23 and 45 hours after the burst where the
intensity becomes consistent with a constant for several hours, perhaps
indicating multiple injections of energy into the GRB/afterglow system.


title: Absolute timing with IBIS, SPI and JEM-X aboard INTEGRAL

abstract:
  We have verified the absolute timing capabilities of the high-energy
instruments aboard INTEGRAL, i.e. the imager IBIS, the spectrometer SPI and the
X-ray monitor JEM-X. Calibration observations of the Crab, contemporaneous with
the Rossi X-ray Timing Explorer (RXTE), have been used to measure the absolute
phase of the main pulse of the Crab pulse profile using the same Jodrell Bank
radio ephemeris. The three INTEGRAL instruments and RXTE give within the
statistical and systematic uncertainties consistent results: The X-ray main
pulse is leading the radio pulse by 280 +/- 40 microsec. Also the shapes of the
X-ray pulse profiles as measured by the different instruments are fully
consistent with each other.


title: Catching NGC4051 in the low state with XMM-Newton

abstract:
  The Narrow Line Seyfert 1 galaxy NGC4051 shows unusual low flux states,
lasting several months, when the 2-10 keV X-ray spectrum becomes unusually hard
(photon index<1) while the spectrum at lower X-ray energies is dominated by a
large soft excess. A Chandra TOO of the low state has shown that the soft
excess and hard components are variable and well-correlated. The variability of
the hard component rules out an origin in a distant reflector. Here we present
results from a recent XMM-Newton TOO of NGC4051 in the low state, which allows
a much more detailed examination of the nature of the hard and soft spectral
components in the low state. We demonstrate that the spectral shape in the low
state is consistent with the extrapolation of the spectral pivoting observed at
higher fluxes. The XMM-Newton data also reveals the warm absorbing gas in
emission, as the drop in the primary continuum flux unmasks prominent emission
lines from a range of ion species.


title:
Combined Long and Short Timescale X-ray Variability of NGC4051 with RXTE
  and XMM-Newton

abstract:
  We present a comprehensive examination of the X-ray variability of the narrow
line Seyfert 1 (NLS1) galaxy NGC4051. We combine over 6.5 years of frequent
monitoring observations by RXTE with a >100ks continuous observation by
XMM-Newton and so present a powerspectral density (PSD) covering an
unprecedented frequency range of over 6.5 decades from <1e-8 to >1e-2 Hz. The
combined RXTE and XMM-Newton PSD is a very good match to the PSD of the
galactic black hole binary system (GBH) Cyg X-1 when in a `high', rather than
`low', state providing the first definite confirmation of an AGN in a `high'
state. We find a break in the PSD at a frequency \nu_{B}=8e-4 Hz. If \nu_{B}
scales linearly with mass then, assuming a black hole (BH) mass of 10 M_solar
for Cyg X-1, we imply a BH mass of 3e-5 M_solar in NGC4051, which is consistent
with the recently reported reverberation mapped value. Hence NGC4051 is
emitting at \sim30% L_{Edd}. We note that the higher energy photons lag the
lower energy ones and that the lag is greater for variations of longer Fourier
period and increases with the energy separation of the bands. Variations in
different wavebands are very coherent at long Fourier periods but the coherence
decreases at shorter periods and as the energy separation between bands
increases. This behaviour is similar to that of GBHs and suggests a radial
distribution of frequencies and photon energies with higher energies and higher
frequencies being associated with smaller radii [ABRIDGED].


title:
Kinetic SZ effect and CMB polarization from subsonic bulk motions of
  dense gas clouds in galaxy cluster cores

abstract:
  Recent CHANDRA observations have revealed the presence of cold fronts in many
clusters of galaxies. The cold fronts are believed to be produced by the bulk
motions of massive, dense, cold gas clouds with respect to the hotter, more
rarefied ambient gas at velocities that can be as high as the speed of sound.
This phenomenon may produce a significant contamination of both the kinetic SZ
effect and the CMB polarization pattern observed in the direction of a cluster.
We estimate the contributions to the kinetic Sunyaev-Zel'dovich (SZ) effect and
to the CMB polarization toward galaxy clusters produced by the bulk motions of
the gas in the inner parts of galaxy clusters. The observed cold fronts probe
the absolute velocities of the gas motion while the induced polarization and
the kinetic SZ effect probe the transverse and the radial components,
respectively. We show that these signals may be easily detected with sensitive
future experiments, opening an exciting new window for studies of galaxy
cluster internal dynamics, and eventually facilitating reconstruction of the
intrinsic cluster polarization of the CMB and the associated measure of the
local CMB quadrupole.


title: Altered Luminosity Functions of Relativistically Beamed Jet Populations

abstract:
  The intrinsic luminosity functions of extremely fast jets found in many
active galaxies and gamma-ray bursts are difficult to measure since their
apparent luminosities are strongly affected by relativistic beaming. Past
studies have only provided analytical predictions for the beamed
characteristics of populations in which all jets have the same Lorentz factor.
However, the jets found in active galaxies are known to span a large range of
speeds. Here we derive analytical expressions for the expected Doppler factor
distributions and apparent (beamed) luminosity functions of randomly-oriented,
two-sided jet populations which have bulk Lorentz factors distributed according
to a simple power-law over a range [G1, G2]. We find that if a jet population
has a uniform or inverted Lorentz factor distribution, its Doppler factor
distribution and beamed luminosity function will be very similar to that of a
jet population with Lorentz factors all equal to G2. In particular, the beamed
and intrinsic luminosity functions will have the same slope at high
luminosities. In the case of a steeply declining Lorentz factor distribution,
the slopes at high luminosities will also be identical, but only up to an
apparent luminosity equivalent to the upper cutoff of the intrinsic luminosity
function. Also, at very high apparent luminosities, the slope will be
proportional to the power law slope of the Lorentz factor distribution. At very
low luminosities, the form of the apparent luminosity function is very
sensitive to the lower cutoff and steepness of the Lorentz factor distribution.
We discuss how it should be possible to recover useful information about the
intrinsic luminosity functions of relativistic jets by studying flux-limited
samples selected on the basis of beamed jet emission.


title:
The Opacity of Spiral Galaxies from Counts of Distant Background
  Galaxies

abstract:
  We have applied the "Synthetic Field Method" on a sample of ~20 nearby
galaxies in order to determine the opacity of their disks. We present
preliminary results on the radial dependence of cold dust absorption for 3
examples. The spirals NGC4535 and NGC4725 show significant absorption at a
half-light radius. UGC2302, a LSB galaxy, shows much less opacity.


title: A new deep SCUBA survey of gravitationally lensing clusters

abstract:
  We have conducted a new deep SCUBA survey, which has targetted 12 lensing
galaxy clusters and one blank field. In this survey we have detected several
sub-mJy sources after correcting for the gravitational lensing by the
intervening clusters. We here present the preliminary results and point out two
highlights.


title:
Circular Polarization of Circumstellar Water Masers: Magnetic Fields of
  AGB stars

abstract:
  We present circular polarization measurements of circumstellar water masers
around 2 Mira variables and 4 supergaint stars. Both an LTE and non-LTE method
are used to analyze the circular polarization and total intensity spectra and
to obtain the magnetic field strength. The non-LTE method is found to be able
to reproduce the observations best. Using this, we find fields from a few
hundred milliGauss up to a few Gauss, indicating a solar-type r^(-2) dependence
of the magnetic field on the distance, which leads to stellar surface magnetic
fields of up to several hundred Gauss. No linear polarization is detected to
less than 1.5%.


title:
GALICS I: A hybrid N-body semi-analytic model of hierarchical galaxy
  formation

abstract:
  This is the first paper of a series that describes the methods and basic
results of the GalICS model (for Galaxies In Cosmological Simulations). GalICS
is a hybrid model for hierarchical galaxy formation studies, combining the
outputs of large cosmological N-body simulations with simple, semi-analytic
recipes to describe the fate of the baryons within dark matter halos. The
simulations produce a detailed merging tree for the dark matter halos including
complete knowledge of the statistical properties arising from the gravitational
forces. We intend to predict the overall statistical properties of galaxies,
with special emphasis on the panchromatic spectral energy distribution emitted
by galaxies in the UV/optical and IR/submm wavelength ranges.
  In this paper, we outline the physically motivated assumptions and key free
parameters that go into the model, comparing and contrasting with other
parallel efforts. We specifically illustrate the success of the model in
comparison to several datasets, showing how it is able to predict the galaxy
disc sizes, colours, luminosity functions from the ultraviolet to far infrared,
the Tully--Fisher and Faber--Jackson relations, and the fundamental plane in
the local universe. We also identify certain areas where the model fails, or
where the assumptions needed to succeed are at odds with observations, and pay
special attention to understanding the effects of the finite resolution of the
simulations on the predictions made. Other papers in this series will take
advantage of different data sets available in the literature to extend the
study of the limitations and predictive power of GalICS, with particular
emphasis put on high-redshift galaxies.


title:
Morphologies and Spectral Energy Distributions of Extremely Red Galaxies
  in the GOODS-South Field

abstract:
  Using U'- through Ks-band imaging data in the GOODS-South field, we construct
a large, complete sample of 275 ``extremely red objects'' (EROs; K_s<22.0,
R-K_s>3.35; AB), all with deep HST/ACS imaging in B_435, V_606, i_775, and
z_850, and well-calibrated photometric redshifts. Quantitative concentration
and asymmetry measurements fail to separate EROs into distinct morphological
classes. We therefore visually classify the morphologies of all EROs into four
broad types: ``Early'' (elliptical-like), ``Late'' (disk galaxies),
``Irregular'' and ``Other'' (chain galaxies and low surface brightness
galaxies), and calculate their relative fractions and comoving space densities.
For a broad range of limiting magnitudes and color thresholds, the relative
number of early-type EROs is approximately constant at 33-44%, and the comoving
space densities of Early- and Late-type EROs are comparable. Mean rest-frame
spectral energy distributions (SEDs) at wavelengths between 0.1 and 1.2 um are
constructed for all EROs. The SEDs are extremely similar in their range of
shapes, independent of morphological type. The implication is that any
differences between the broad-band SEDs of Early-type EROs and the other types
are relatively subtle, and there is no robust way of photometrically
distinguishing between different morphological types with usual
optical/near-infrared photometry.


title:
The Evolutionary Status of M3 RR Lyrae Variables: Breakdown of the
  Canonical Framework?

abstract:
  In order to test the prevailing paradigm of horizontal-branch (HB) stellar
evolution, we use the large databases of measured RR Lyrae parameters for the
globular cluster M3 (NGC 5272) recently provided by Bakos et al. and Corwin &
Carney. We compare the observed distribution of fundamentalized periods against
the predictions of synthetic HBs. The observed distribution shows a sharp peak
at P_f ~ 0.55 d, which is primarily due to the RRab variables, whereas the
model predictions instead indicate that the distribution should be more uniform
in P_f, with a buildup of variables with shorter periods (P_f < 0.5 d).
Detailed statistical tests show, for the first time, that the observed and
predicted distributions are incompatible with one another at a high
significance level. We show that the sharp peak in the M3 period distribution
receives a significant contribution from the Blazhko variables in the cluster.
We also show that M15 (NGC 7078) and M68 (NGC 4590) show similar peaks in their
P_f distributions, which in spite of being located at a similar P_f value as
M3's, can be primarily ascribed to the RRc variables. Again similar to M3, a
demise of RRc variables towards the blue edge of the instability strip is
present in these two globulars. This is again in sharp contrast with the
evolutionary scenario, which also foresees a strong buildup of RRc variables
with short periods in OoII globulars. We speculate that, in OoI systems, RRab
variables may get "trapped" close to the transition line between RRab and RRc
pulsators as they evolve to the blue, whereas in OoII systems it is the RRc
variables that may get "trapped" instead, as they evolve to the red, before
changing their pulsation mode to RRab. Such a scenario is supported by the
available CMDs and Bailey diagrams for M3, M15, and M68.


title:
Chondrule Formation and Protoplanetary Disk Heating by Current Sheets in
  Non-Ideal Magnetohydrodynamic Turbulence

abstract:
  We study magnetic field steepening due to ambipolar diffusion (Brandenburg &
Zweibel 1994) in protoplanetary disk environments and draw the following
conclusions. Current sheets are generated in magnetically active regions of the
disk where the ionization fraction is high enough for the magnetorotational
instability to operate. In late stages of solar nebula evolution, the surface
density is expected to have lowered and dust grains to have gravitationally
settled to the midplane. If the local dust-to-gas mass ratio near the midplane
is increased above cosmic abundances by factors > 10^3, current sheets reach
high enough temperatures to melt millimeter-sized dust grains, and hence may
provide the mechanism to form meteoritic chondrules. In addition, these current
sheets possibly explain the near-infrared excesses observed in spectral energy
distributions (SEDs) of young stellar objects. Direct imaging of protoplanetary
disks via a nulling interferometer or, in the future, a multi-band, adaptive
optics coronagraph can test this hypothesis.


title: Discovery of a double ring in the dwarf galaxy Mrk409

abstract:
  We report the discovery of a double ring of emission-line regions around the
nucleus of the Blue Compact Dwarf (BCD) galaxy Mrk409 as seen by deep,
ground-based Halpha images. Echelle spectroscopy obtained at Magellan-I with
MIKE shows the presence of ionized gas flowing out of the galaxy from a very
massive (>7E6 Msun) nuclear starburst with projected expansion velocities of
\~50 km/s. Different scenarios for the formation of these rings are discussed.
While the innermost, nuclear ring is most probably formed by the interaction of
a starburst-driven shock with the surrounding interstellar medium, the origin
of the outer ring is less clear.


title:
Toward reconstruction of dynamics of the Universe from distant
  supernovae type Ia

abstract:
  We demonstrate a model-independent method of estimating qualitative dynamics
of an accelerating universe from observations of distant type Ia supernovae.
Our method is based on the luminosity-distance function, optimized to fit
observed distances of supernovae, and the Hamiltonian representation of
dynamics for the quintessential universe with a general form of equation of
state $p=w(a(z))\rho$. Because of the Hamiltonian structure of FRW dynamics
with the equation of state $p = w(a(z)) \rho$, the dynamics is uniquelly
determined by the potential function $V(a)$ of the system. The effectiveness of
this method in discrimination of model parameters of Cardassian evolution
scenario is also given. Our main result is the following, restricting to the
flat model with the current value of $\Omega_{m,0}=0.3$, the constraints at
$2\sigma$ confidence level to the presence of $\rho^{n}$ modification of the
FRW models are $-0.50 \lesssim n \lesssim 0.36$.


title: Hot Gas in the Circumstellar Bubble S308

abstract:
  S308 is a circumstellar bubble blown by the WN4 star HD50896. It is one of
the only two single-star bubbles that show detectable diffuse X-ray emission.
We have obtained XMM-Newton EPIC observations of the northwest quadrant of
S308. The diffuse X-ray emission shows a limb-brightened morphology, with a
clear gap extending from the outer edge of the diffuse X-ray emission to the
outer rim of the nebular shell. The X-ray spectrum of the diffuse emission is
very soft, and is well fitted by an optically thin plasma model for a
N-enriched plasma at temperatures of ~1.1x10^6 K. A hotter gas component may
exist but its temperature is not well constrained as it contributes less than
6% of the observed X-ray flux. The total X-ray luminosity of S308, extrapolated
from the bright northwest quadrant, is <=(1.2+-0.5)x10^{34} ergs/s. We have
used the observed bubble dynamics and the physical parameters of the hot
interior gas of S308 in conjunction with the circumstellar bubble model of
Garcia-Segura & Mac Low (1995) to demonstrate that the X-ray-emitting gas must
be dominated by mixed-in nebular material.


title: Competition Between Gravitational and Scalar Field Radiation

abstract:
  Recent astrophysical observations have provided strong evidence that the
present expansion of the universe is accelerating, powered by the energy
density associated with a cosmological term. Assuming the latter to be not
simply a constant term but a "quintessence" field, we study the radiation of
quanta of such a "quintessence" field ("quintons") by binary systems of
different types and compare intensities to those of standard tensor
gravitational wave emission. We consider both the case in which the
quintessence field varies only over cosmological distances and the case in
which it is modified spatially by (strong) gravitational fields, a condition
that results in bounds on the gradient of the scalar field. We show that, in
both the first case and, because of a bound we derive from the Hulse-Taylor
pulsar, in the second, there is not sufficient quinton radiation to affect
expected LISA and LIGO gravity wave signals from binary systems. We show that,
in the second case, the Large Hadron Collider is capable of setting a bound
similar to that from the binary pulsar.


title:
Single and Composite Hot Subdwarf Stars in the Light of 2MASS All-Sky
  Photometry

abstract:
  Utilizing the Two Micron All Sky Survey (2MASS) All-Sky Data Release Catalog,
we have retrieved useful near-IR J, H, and Ks magnitudes for more than 800 hot
subdwarfs (sdO and sdB stars) drawn from the "Catalogue of Spectroscopically
Identified Hot Subdwarfs" (Kilkenny, Heber, & Drilling 1988, 1992). This sample
size greatly exceeds previous studies of hot subdwarfs. We find that, of the
hot subdwarfs in Kilkenny et al., ~40% in a magnitude limited sample have
colors that are consistent with the presence of an unresolved late type (FGK)
companion. Binary stars are over-represented in a magnitude limited sample. In
an approximately volume limited sample the fraction of composite-color binaries
is ~25%.


title: Are All Hot Subdwarf Start in Close Binaries?

abstract:
  We discuss whether the hypothesis that "all (or most) subdwarfs are in close
binaries" is supported by the frequently reported observations of
photometrically or spectroscopically composite character of many hot subdwarf
stars. By way of a possible counter-argument, we focus on resolved companions
(optical pairs) of hot subdwarf stars. On a statistical basis, many of these
are physically associated with the hot subdwarfs, i.e. are common proper motion
pairs. These resolved pairs make a several percent contribution to the catalog
of hot subdwarf stars per decade in projected separation. If they are just the
relatively wide members of a binary population similar to the local G-dwarf
binary population (Duquennoy & Mayor 1991), which has a very wide distribution
of orbital separations, then many of the unresolved but composite hot subdwarf
binaries may not be "close" in the astrophysical sense. In that case, binary
channels for hot subdwarf formation may be less important than thought, or must
involve companions (white dwarfs) that do not result in a composite spectrum
system.


title:
Discovery of New Milky Way Star Cluster Candidates in the 2MASS Point
  Source Catalog II. Physical Properties of the Star Cluster CC01

abstract:
  Three new obscured Milky Way clusters were detected as surface density peaks
in the 2MASS point source catalog during our on-going search for hidden
globular clusters and massive Arches-like star clusters. One more cluster was
discovered serendipitously during a visual inspection of the candidates.
  The first deep J, H, and Ks imaging of the cluster [IBP2002] CC01 is
presented. We estimated a cluster age of ~1-3 Myr, distance modulus of
(m-M)0=12.56+-0.08 mag (D=3.5 Kpc), and extinction of AV~7.7 mag. We also
derived the initial mass function slope for the cluster: Gamma=-2.23+-0.16. The
integration over the initial mass function yielded a total cluster mass
M_{total}<=1800+-200Msol. CC01 appears to be a regular, not very massive star
cluster, whose formation has probably been induced by the shock front from the
nearby HII region Sh2-228.


title:
The Chemical Evolution of Mg Isotopes vs. the Time Variation of the Fine
  Structure Constant

abstract:
  The many-multiplet method applied to high redshift quasar absorption spectra
has indicated a possible time variation of the fine structure constant.
Alternatively, a constant value of alpha is consistent with the observational
analysis if a non-solar isotopic ratio of Mg24,25,26 occurs at high redshift.
In particular, a higher abundance of the heavier isotopes Mg25,26 are required
to explain the observed multiplet splitting. We show that the synthesis of
Mg25,26 at the base of the convective envelope in low-metallicity asymptotic
giant branch stars, combined with a simple model of galactic chemical
evolution, can produce the required isotopic ratios and is supported by recent
observations of high abundances of the neutron-rich Mg isotopes in metal-poor
globular-cluster stars. We conclude that the present data based on high
redshift quasar absorption spectra may be providing interesting information on
the nucleosynthetic history of such systems, rather than a time variation of
fundamental constants.


title:
The Metallicity of Pre-Galactic Globular Clusters: Observational
  consequences of the first stars

abstract:
  We explore a scenario where metal-poor globular clusters (GCs) are enriched
by the first supernovae in the Universe. If the first stars in a 10^7 Msun dark
halo were very massive (>180 Msun), then a pair instability supernova from a
single massive star can produce sufficient iron to enrich 10^6 Msun of
pristine, primordial gas to [Fe/H] ~ -2. In such a scenario, where a single
massive star acts as a seed for halo GCs, the accurate abundance analysis of GC
stars would allow a direct measurement of the Population III initial mass.
Using the latest theoretical yields for zero metallicity stars in the mass
range 140-260 Msun, we find that the metals expelled from a ~230 Msun star are
consistent with [Si/Fe] and [Ca/Fe] observed in GC stars. However, no single
star in this mass range can simultaneously explain all halo GC heavy-element
abundance ratios, such as [V/Fe], [Ti/Fe] and [Ni/Fe]. These require a
combination masses for the Population III stellar progenitors. The various
observational consequences of this scenario are discussed.


title:
Structures of Rotating Traditional Neutron Stars and Hyperon Stars in
  the Relativistic $\sigma-\omega$ Model

abstract:
  The influence of the rotation on the total masses and radii of the neutron
stars are calculated by the Hartle's slow rotation formalism, while the
equation of state is considered in a relativistic $\sigma-\omega$ model.
Comparing with the observation, the calculating result shows that the double
neutron star binaries are more like hyperon stars and the neutron stars of
X-ray binaries are more like traditional neutron stars. As the changes of the
mass and radius to a real neutron star caused by the rotation are very small
comparing with the total mass and radius, one can see that Hartle's approximate
method is rational to deal with the rotating neutron stars. If three property
values: mass, radius and period are observed to the same neutron star, then the
EOS of this neutron star could be decided entirely.


title:
Cosmic Dispersion Measure from Gamma-Ray Burst Afterglows: Probing the
  Reionization History and the Burst Environment

abstract:
  We show a possible way to measure the column density of free electrons along
the light path, the so-called Dispersion Measure (DM), from the early $[\sim
415 (\nu/1 {\rm GHz})^{-2} ({\rm DM}/10^{5} {\rm pc} {\rm cm}^{-3}) {\rm s}]$
radio afterglows of the gamma-ray bursts. We find that the proposed Square
Kilometer Array can detect bright radio afterglows around the time $\sim
10^{3}(\nu/160 {\rm MHz})^{-2}$ s to measure the intergalactic DM ($\simg 6000$
pc cm$^{-3}$ at redshift $z>6$) up to $z\sim 30$, from which we can determine
the reionization history of the universe and identify the missing warm-hot
baryons. At low $z$, DM in the host galaxy may reach $\sim 10^{5}$ pc cm$^{-3}$
depending on the burst environment, which may be probed by the current
detectors. Free-free absorption and diffractive scattering may also affect the
radio emission in a high density.


title: On the Central Engine of short Gamma-ray Bursts

abstract:
  We assess two mechanisms to produce a short GRB from a neutron star
coalescence: the annihilation of neutrino and anti-neutrino pairs and magnetic
processes within the remnant. We find that the neutrino-driven wind from the
remnant can collimate the jets produced via neutrino annihilation into a small
solid angle. This mechanism satisfies the observational constraints on the
apparent luminosity and on the merger event rate. Moreover, the supermassive
neutron star that is formed in the center of the remnant is expected to act as
a convective dynamo reaching equipartition field strengths within fractions of
a second. The associated spin-down time scale is similar to the typical
duration of short GRBs.


title: Formation of Dwarf Galaxies during the Cosmic Reionization

abstract:
  We reanalyze the photoevaporation problem of subgalactic objects irradiated
by UVB radiation in a reionized universe. For the purpose, we perform
three-dimensional radiation smoothed-particle-hydrodynamics calculations, where
the radiative transfer is solved by a direct method and also the
non-equilibrium chemistry of primordial gas including H$_2$ molecules is
incorporated. Attention is concentrated on radiative transfer effects against
UVB for the formation of subgalactic objects with $T_{\rm vir}\la 10^4$K. We
consider the reionization model with $z_{\rm reion} \approx 7$ and also the
earlier reionization model ($z_{\rm reion} \approx 17$) inferred by the WMAP.
We find that the star formation is suppressed appreciably by UVB, but baryons
at high-density peaks are self-shielded even during the reionization, forming
some amount of stars eventually. In that sense, the photoevaporation for
subgalactic systems is not so perfect as argued by one-dimensional spherical
calculations. The final stellar fraction depends on the collapse epoch and the
mass of system, but almost regardless of the reionization epoch. For instance,
a few tenths of formed stars are born after the cosmic reionization in $z_{\rm
reion} \approx 7$ model, while more than 90% stars are born after the
reionization in the WMAP reionization model. Thus, effects of UVB feedback on
the substructure problem with CDM scenario should be evaluated with careful
treatment of the radiative transfer. The star clusters formed at high-density
peaks coalesce with each other in a dissipationless fashion in a dark matter
potential, resultantly forming a spheroidal system. As a result, these low-mass
galaxies have large mass-to-light ratios such as observed in dwarf spheroidals
in the Local Group.


title: INTEGRAL-RXTE observations of Cygnus X-1

abstract:
  We present first results from contemporaneous observations of Cygnus X-1 with
INTEGRAL and RXTE, made during INTEGRAL's performance verification phase in
2002 November and December. Consistent with earlier results, the 3-250 keV data
are well described by Comptonization spectra from a Compton corona with a
temperature of kT~50-90 keV and an optical depth of tau~1.0-1.3 plus reflection
from a cold or mildly ionized slab with a covering factor of Omega/2pi~0.2-0.3.
A soft excess below 10 keV, interpreted as emission from the accretion disk, is
seen to decrease during the 1.5 months spanned by our observations. Our results
indicate a remarkable consistency among the independently calibrated detectors,
with the remaining issues being mainly related to the flux calibration of
INTEGRAL.


title:
Towards Constraints on Dark Energy from Absorption Spectra of Close
  Quasar Pairs

abstract:
  A comparison between the line of sight power spectrum of absorption in the
Lyman-alpha forest and the cross power spectrum between the absorption in
neighboring lines of sight offers an evolution-free means to constrain the
cosmological constant, or dark energy. Using cosmological simulations, we
consider a maximum likelihood method to obtain constraints from this
comparison. In our method, measurements of the auto and cross spectra from
observations are compared with those from a multi-parameter grid of simulated
models of the intergalactic medium. We then marginalize over nuisance
parameters to obtain constraints on the cosmological constant. Redshift space
distortions due to peculiar velocities and thermal broadening, a potential
difficulty in applying this test, are explicitly modeled in our simulations. To
illustrate our method, we measure the cross spectrum from a new sample of five
close quasar pairs, with separations of 0.5 to 3 arcmin. We attempt to obtain a
constraint on Omega_Lambda, but find only weak constraints. An
Einstein-de-Sitter cosmology is, however, disfavored by the data at a ~ 2 sigma
confidence level. We consider the power of future observations, paying
particular attention to the effects of spectral resolution and shot-noise. We
find that ~ 50 moderate resolution, FWHM ~ 150 km/s, close separation (~ 30-120
arcsec) pairs should allow a (2 sigma) constraint on Omega_Lambda at the level
of 15%, if other modeling parameters are determined through other means. We
find that there is a sizeable gain from observing very close, ~ 30 arcsec,
separation pairs provided they are observed with high spectral resolution. A
sample of ~ 10 such pairs gives similar constraints to the 50 moderate
resolution pairs mentioned above.


title: New constraints on varying $\alpha$

abstract:
  We present a summary of recent constraints on the value of the fine-structure
constant at the epoch of decoupling from the recent observations made by the
Wilkinson Microwave Anisotropy Probe (WMAP) satellite. Within the set of models
considered, a variation of the value of $\alpha$ at decoupling with respect to
the present-day value is now bounded to be smaller than 2% (6%) at 95%
confidence level. We point out that the existence of an early reionization
epoch as suggested by the above measurements will, when more accurate cosmic
microwave background polarization data is available, lead to considerably
tighter constraints. We find that the tightest possible constraint on $\alpha$
is about $0.1 %$ using CMB data alone--tighter constraints will require further
(non-CMB) priors.


title: Extinction Map of the Galactic center: OGLE-II Galactic bulge fields

abstract:
  We present the reddening (E(V-I)) and Extinction maps in V-band (A_V) and
I-band (A_I) for 48 Optical Gravitational Lensing Experiment II (OGLE-II)
Galactic bulge (GB) fields, covering a range of $-11^\circ <l< 11^\circ$, with
the total area close to 11 square degrees. These measurements are based on
two-band photometry of Red Clump Giant (RCG) stars in OGLE-II VI maps of GB. We
confirm the anomalous value of the ratio of total to selective extinction
$R_{VI} = A_V / E(V-I) = 1.9 \sim 2.1$, depending on the line of sight, as
measured by Udalski (2003). By using the average value of $R_{VI}=1.964$ with
the standard deviation sdev=0.085, we measured E(V-I), A_V and A_I, and we
obtained extinction and reddening maps with a high spatial resolution of $
26.7''\sim 106.8''$, depending on the stellar density of each field. We assumed
that average, reddening corrected colours of red clump giants are the same in
every field. The maps cover the range 0.42<E(V-I)<3.5, 0.83<A_V<6.9 and
0.41<A_I<3.4 mag respectively. The zero points of these maps are calibrated by
using V-K colours of 20 RR Lyrae ab variables (RRab) in Baade's window. The
apparent reddening corrected I-band magnitudes of the RCGs change by +0.4 mag
while the Galactic coordinate l varies from $+5^{\circ}$ to $-5^{\circ}$,
indicating that these stars are in the Galactic Bar. The reddening corrected
colour of RRab and RCGs in GB are consistent with colours of local stars, while
in the past these colours were claimed to be different.


title: Light-weight Local Group Dwarf Spheroidal Galaxies

abstract:
  A simple and natural explanation for the dynamics and morphology of the Local
Group Dwarf Spheroidal galaxies, Draco (Dra) and Ursa Minor (UMi), is that they
are weakly unbound stellar systems with no significant dark matter component. A
gentle, but persistent, Milky Way (MW) tide has left them in their current
kinematic and morphological state. This short paper reviews the parametric
tidal interaction model which accounts for their behavior and discusses new
statistical evidence from the observed stellar distribution in Dra which
implies that its total mass is not dominated by collisionless dark matter (DM).


title: Measuring White Dwarf Accretion Rates via their Effective Temperatures

abstract:
  Our previous theoretical study of the impact of an accreting envelope on the
thermal state of an underlying white dwarf (WD) has yielded equilibrium core
temperatures, classical nova ignition masses and thermal luminosities for WDs
accreting at time averaged rates of <Mdot> = 10^-11 - 10^-8 Msun/yr. These
<Mdot>'s are appropriate to WDs in cataclysmic variables (CVs) of P_orb <~ 7
hr, many of which accrete sporadically as Dwarf Novae. Approximately thirty
nonmagnetic Dwarf Novae have been observed in quiescence, when the accretion
rate is low enough for spectral detection of the WD photosphere, and a
measurement of T_eff. We use our theoretical work to translate the measured
T_eff's into local time-averaged accretion rates, confirming the factor of ten
drop in <Mdot> predicted for CV's as they transit the period gap. For DN below
the period gap, we show that if <Mdot> is that given by gravitational radiation
losses alone, then the WD masses are > 0.8 Msun. An alternative conclusion is
that the masses are closer to 0.6 Msun and <Mdot> is 3-4 times larger than that
expected from gravitational radiation losses. In either case, it is very
plausible that a subset of CVs with P_orb < 2 hours will have T_eff's low
enough for them to become non-radial pulsators, as discovered by van Zyl and
collaborators in GW Lib.


title:
Scattered Light from Close-in Extrasolar Planets: Prospects of Detection
  with the MOST Satellite

abstract:
  The ultra-precise photometric space satellite MOST (Microvariability and
Oscillations of STars) will provide the first opportunity to measure the
albedos and scattered light curves from known short-period extrasolar planets.
Due to the changing phases of an extrasolar planet as it orbits its parent
star, the combined light of the planet-star system will vary on the order of
tens of micromagnitudes. The amplitude and shape of the resulting light curve
is sensitive to the planet's radius and orbital inclination, as well as the
composition and size distribution of the scattering particles in the planet's
atmosphere.
  To predict the capabilities of MOST and other planned space missions, we have
constructed a series of models of such light curves, improving upon earlier
work by incorporating more realistic details such as: limb darkening of the
star, intrinsic granulation noise in the star itself, tidal distortion and
back-heating, higher angular resolution of the light scattering from the
planet, and exploration of the significance of the angular size of the star as
seen from the planet. We use photometric performance simulations of the MOST
satellite, with the light curve models as inputs, for one of the mission's
primary targets, $\tau$ Bo\"otis. These simulations demonstrate that, even
adopting a very conservative signal detection limit of 4.2 $\mu$mag in
amplitude (not power), we will be able to either detect the $\tau$ Bo\"otis
planet light curve or put severe constraints on possible extrasolar planet
atmospheric models.


title: High Precision Stellar Radial Velocities in the Galactic Center

abstract:
  We present radial velocities for 85 cool stars projected onto the central
parsec of the Galaxy. The majority of these velocities have relative errors of
$\sim$1 km/s, or a factor of $\sim$30-100 smaller than those previously
obtained with proper motion or other radial velocity measurements for a similar
stellar sample. The error in a typical individual stellar velocity, including
all sources of uncertainty, is 1.7 km/s. Two similar data sets were obtained
one month apart, and the total error in the relative velocities is 0.80 km/s\
in the case where an object is common to both data sets. The data are used to
characterize the velocity distribution of the old population in the Galctic
Center. We find that the stars have a Gaussian velocity distribution with a
mean heliocentric velocity of $-10.1\pm$11.0 km/s (blueshifted) and a standard
deviation of 100.9$\pm7.7$ km/s; the mean velocity of the sample is consistent
with no bulk line-of-sight motion with respect to the Local Standard of Rest.
At the 1 sigma level, the data are consistent with a symmetric velocity
distribution about any arbitrary axis in the plane of the sky. We find evidence
for a flattening in the distribution of late-type stars within a radius of
$\sim$0.4 \pc, and infer a volume density distribution of r$^{-1/4}$ in this
region. Finally, we establish a first epoch of radial velocity measurements
which can be compared to subsequent epochs to measure small accelerations (1
km/s/yr), corresponding to the magnitude expected over a timespan of several
years for stars nearest to Sgr A*.


title:
Measuring $\alpha$ in the Early Universe: CMB Polarization, Reionization
  and the Fisher Matrix Analysis

abstract:
  We present a detailed analysis of present and future Cosmic Microwave
Background constraints of the value of the fine-structure constant, $\alpha$.
We carry out a more detailed analysis of the WMAP first-year data, deriving
state-of-the-art constraints on $\alpha$ and discussing various other issues,
such as the possible hints for the running of the spectral index. We find, at
95% C.L. that $0.95 < \alpha_{\text{dec}} / \alpha_0 < 1.02$. Setting $dn_S
/dlnk=0$, yields $0.94< \alpha_{\text{dec}} / \alpha_0 < 1.01$ as previously
reported. We find that a lower value of $\alpha / \alpha_0$ makes a value of $d
n_S /dlnk = 0$ more compatible with the data. We also perform a thorough Fisher
Matrix Analysis (including both temperature and polarization, as well as
$\alpha$ and the optical depth $\tau$), in order to estimate how future CMB
experiments will be able to constrain $\alpha$ and other cosmological
parameters. We find that Planck data alone can constrain $\tau$ with a accuracy
of the order 4% and that this constraint can be as small as 1.7% for an ideal
cosmic variance limited experiment. Constraints on $\alpha$ are of the order
0.3% for Planck and can in principle be as small as 0.1% using CMB data alone -
tighter constraints will require further (non-CMB) priors.


title:
Measurements of accretion disc corona size in LMXB: consequences for
  Comptonization and LMXB models

abstract:
  We present results of measurements of the radial extent of the accretion disc
corona in low mass X-ray binaries. These results prove conclusively the
extended nature of the ADC, with radial extent varying from 20,000 km in the
faintest sources to 700,000 km in the brightest, a substantial fraction of the
accretion disc radius, typically 15%. This result rules out the Eastern model
for LMXB which is extensively used, in which the Comptonizing region is a small
central region. The ADC size depends strongly on the 1 - 30 keV source
luminosity via a simple relationship r_ADC = L^{0.88 +/- 0.16} (99% confidence)
close to a simple proportionality. We also present limited evidence that the
ADC size agrees with the Compton radius r_C, or maximum radius for hydrostatic
equilibrium. The results are consistent with models in which an extended ADC is
formed by illumination of the disc by the central source. The dependence on
luminosity may reflect the known decrease of coronal temperature as the source
luminosity increases leading to an increase of r_C. The extended nature of the
ADC means that the seed photons for Comptonization must consist of emission
from the disc to the same radial extent as the corona, providing copious
supplies of soft seed photons. We demonstrate the importance of the size of the
ADC to the correct description of Comptonization, and derive the Comptonized
spectrum of a LMXB based on thermal Comptonization of these seed photons and
show that this differs fundamentally from that of the Eastern model which
assumes a cut-off below 1 keV. Finally, we argue that our results are
inconsistent with the assumption often made that the X-ray emission of
accreting Black Holes and Neutron Stars has a common mechanism depending on the
properties of the accretion flow only.


title: Gas and Dust in the Extremely Red Object ERO J164502+4626.4

abstract:
  We report the first detection of the lowest CO transition in a sub-millimetre
bright galaxy and extremely red object (ERO) at z = 1.44 using the Very Large
Array. The total J = 1 - 0 line luminosity of ERO J164502+4626.4 is (7+-1) x
10^{10} K km s^{-1} pc^2, which yields a total molecular gas mass of ~6 x
10^{10} Msun. We also present a map of the 850-um continuum emission obtained
using SCUBA, from which we infer a far-IR luminosity and dust mass of L_FIR ~ 9
x 10^{12} Lsun and M_d ~ 9 x 10^{8} Msun. We find tentative evidence that the
CO and sub-mm dust emission is extended over several tens of kpc. If confirmed
by high-resolution imaging, this implies that ERO J164502+4626.4 is not simply
a high redshift counterpart of a typical Ultra Luminous Infrared Galaxy
(ULIRG).


title: Properties of CO Molecular Gas in IR Luminous Galaxies

abstract:
  We present the properties of the 12CO(1-0) and (3-2) line emission from the
nuclei of 60 IR luminous SLUGS galaxies. This subsample is flux limited at S60
> 5.24 Jy with FIR luminosities mostly at LFIR > 10^10 Lo. The emission line
strengths of 12CO(1-0) and (3-2) transitions were compared at a common
resolution of ~ 15", and the line ratios r31 vary from 0.22 to 1.72 with a mean
value of 0.66 for the sources observed, indicating a large spread of the degree
of excitation of CO in the sample. Our analysis shows that (1) there is a
non-linear relation between CO and FIR luminosities, such that their ratio
LCO/LFIR decreases linearly with increasing LFIR, (2) we find a possible
dependence of the degree of CO gas excitation on the efficiency of star forming
activity, (3) using the large velocity gradient (LVG) approximation to model
the observed data, the results show that the mean value of the CO-to-H2
conversion factor $X$ for the SLUGS sample is lower by a factor of 10 compared
to the conventional value derived for the Galaxy, assuming that the abundance
of CO relative to H2 is 10^-4, (4) due to a contribution to the SCUBA
brightness measurement by 12CO(3-2) emission, the average dust mass is reduced
by 25-38%, and the mean global gas-to-dust mass ratio is reduced from 430 to
360, but is further reduced to 100 when applied to the nuclear regions of the
SLUGS galaxies, (5) for a subset of 12 galaxies with H I maps, we derive a mean
total face-on surface density of H2+H I of about 42 Mo pc^-2 within ~ 2 kpc of
the nucleus, which is intermediate between that in galaxies like our own and
those with strong star formation.


title:
Proper-Motion Measurements with the VLA. II. Observations of
  Twenty-eight Pulsars

abstract:
  Using the Very Large Array, we have measured the proper motions of
twenty-eight radio pulsars. On average, the pulsars studied are fainter and
more distant than those studied in earlier work, reducing the selection biases
inherent in surveys restricted to the Solar neighborhood. The typical
measurement precision achieved is a few milliarcseconds per year, corresponding
to a few tens of kilometers per second for a pulsar a kiloparsec away. While
our results compare well with higher-precision measurements done using
very-long baseline interferometry, we find that several earlier proper motion
surveys appear to have reported overly optimistic measurement uncertainties,
most likely because of a failure to fully account for ionospheric effects. We
discuss difficulties inherent in estimating pulsar velocities from proper
motions given poorly constrained pulsar distances. Our observations favor a
distribution with 20% of pulsars in a low velocity component (sigma_1D = 99
km/s) and 80% in a high velocity component (sigma_1D = 294 km/s). Furthermore,
our sample is consistent with a scale height of pulsar birthplaces comparable
to the scale height of the massive stars that are their presumed progenitors.
No evidence is found in our data for a significant population of young pulsars
born far from the plane. We find that estimates of pulsar ages based on
kinematics agree well with the canonical spin-down age estimate, but agreement
is improved if braking indexes are drawn from a Gaussian distribution centered
at n=3 with width 0.8.


title:
Inter-cluster Filaments of Galaxies Programme: Pilot Study Survey and
  Results

abstract:
  We present results from a pilot study of a new wide-field, multicolour (BVR)
CCD imaging project, designed to examine galaxy evolution along large scale
filaments that connect clusters of galaxies at intermediate redshifts (0.08 < z
< 0.20). Our pilot dataset is based on 0.56 square degrees of observations
targeted on Abell 1079 and Abell 1084 using the Wide Field Imager on the
Anglo-Australian Telescope. We describe our data reduction pipeline and show
that our photometric error is 0.04 mags. By selecting galaxies that lie on the
colour-magnitude relation of the two clusters we verify the existence of a low
density (approx 3-4 square Mpc) filament population conjoining them at a
distance of > 3 r_{Abell} from either cluster. By applying a simple field
correction, we characterize this filament population by examining their colour
distribution on a (V-R)-(B-V) plane. We confirm the galaxian filament detection
at a 7.5 sigma level using a cut at M_V=-18 and we discuss their broad
properties.


title:
GRB Formation Rates inferred from the Spectral Peak Energy - Luminosity
  Relation

abstract:
  We investigate the GRB formation rate based on the relation between the
spectral peak energy ($E_{p}$) and the isotropic luminosity. The
$E_{p}$--luminosity relation covers the energy range of 50 -- 2000 keV and the
luminosity range of $10^{50}$--$10^{54} erg/s, respectively. We find that the
relation is considerably tighter than similar relations suggested previously.
Using $E_{p}$--luminosity relation, we estimate the luminosity and the redshift
of 684 GRBs with the unknown distances and derive the GRB formation rate as a
function of the redshift. For $0 \le z \le 2$, the GRB formation rate is well
correlated with the star formation rate while it increases monotonously from
$z\sim 2$ out to $z \sim 12$. This behavior is consistent with the results of
previous works using the lag--luminosity relation or the
variability--luminosity relation.


title:
Population and dynamical state of the eta Chamaeleontis sparse young
  open cluster

abstract:
  We report new results in our continuing study of the unique compact (1 pc
extent), nearby (d = 97 pc), young (t = 9 Myr) stellar cluster dominated by the
B9 star eta Chamaeleontis. An optical photometric survey spanning 1.3 x 1.3 pc
adds two M5-M5.5 weak-lined T Tauri (WTT) stars to the cluster inventory which
is likely to be significantly complete for primaries with masses > 0.15 M_sun.
The cluster now consists of 17 primaries and approximately 9 secondaries lying
within 100 AU of their primaries. The apparent distribution of 9:7:1
single:binary:triple systems shows 2-4 x higher multiplicity than in the field
main sequence stars, and is comparable to that seen in other pre-main sequence
(PMS) populations. The initial mass function (IMF) is consistent with that of
rich young clusters and field stars. By extending the cluster IMF to lower
masses, we predict 10-14 additional low mass stars with 0.08 < M < 0.15 M-sun
and 10-15 brown dwarfs with 0.025 < M < 0.08 M_sun remain to be discovered. The
eta Cha cluster extends the established stellar density and richness
relationship for young open clusters. The radial distribution of stars is
consistent with an isothermal sphere, but mass segregation is present with > 50
percent of the stellar mass residing in the inner 6 arcmin (0.17 pc).
Considering that the eta Cha cluster is sparse, diffuse and young, the cluster
may be an ideal laboratory for distinguishing between mass segregation that is
primordial in nature, or arising from dynamical interaction processes.


title: The ATNF Pulsar Catalogue

abstract:
  The number of known pulsars has significantly increased over the previous few
years. We have searched the literature to find papers announcing the discovery
of pulsars or giving improved parameters for them. Data from the papers have
been entered into a new pulsar catalogue that can be accessed via a web
interface or from the command line (on Solaris or Linux machines). The user may
request over 120 different parameters, select pulsars of interest, generate
custom variables and choose between different ways of displaying or tabulating
the data. Full bibliographic references are available on all observed
parameters.


title: Dynamical Effects from Asteroid Belts for Planetary Systems

abstract:
  The orbital evolution and stability of planetary systems with interaction
from the belts is studied using the standard phase-plane analysis. In addition
to the fixed point which corresponds to the Keplerian orbit, there are other
fixed points around the inner and outer edges of the belt. Our results show
that for the planets, the probability to move stably around the inner edge is
larger than the one to move around the outer edge. It is also interesting that
there is a limit cycle of semi-attractor for a particular case. Applying our
results to the Solar System, we find that our results could provide a natural
mechanism to do the orbit rearrangement for the larger Kuiper Belt Objects and
thus successfully explain the absence of these objects beyond 50 AU.


title: Non-thermal phenomena in galaxy clusters

abstract:
  The recent evidences of the presence of magnetic fields and relativistic
particles in galaxy clusters are reviewed. The existence of microG-level
magnetic fields in cluster atmospheres appears well established from the
detection of diffuse radio emission and from studies of Rotation Measure. The
fact that the diffuse radio emission is not common in clusters favours the
hypothesis that the population of relativistic particles, produced during the
cluster formation by AGNs or star formation, are reaccelerated by recent
cluster merger processes.


title:
3mm & 7mm VLBA Observations of SiO masers: probing the close stellar
  environment of the bipolar Proto Planetary Nebulae OH231.8+4.2

abstract:
  We present milliarsecond-resolution maps of the SiO maser emission $v$=1
J=2--1 (3 mm) in the bipolar post-AGB nebula OH 231.8+4.2, and compare them
with our previous observations of the $v$=2 J=1--0 line (7 mm). Our
observations show that the SiO masers arise in several bright spots forming a
structure elongated in a direction perpendicular to the symmetry axis of the
nebula. This, and the complex velocity gradient observed, is consistent with
the presence of an equatorial torus in rotation and with an infall of material
towards the star.


title: Extremely red galaxies: dust attenuation and classification

abstract:
  We re-address the classification criterion for extremely red galaxies (ERGs)
of Pozzetti and Mannucci (2000 -- PM00), which aims to separate, in the Ic-K
(or Rc-K) vs. J-K colour--colour diagram, passively evolving, old (> 1 Gyr)
stellar populations in a dust-free environment, associated with ellipticals
(Es), from dusty starburst galaxies (DSGs), both at 1 < z < 2. We explore a
category of objects not considered previously, i.e., galaxies forming in this
redshift range on short (0.1 Gyr) timescales and observed also in their early,
dusty post-starburst phase. We also investigate the impact of structure of the
dusty medium and dust amount on the observed optical/near-IR colours of high-z
DSGs/DPSGs, through multiple-scattering radiative transfer calculations for a
dust/stars configuration and an extinction function calibrated with nearby
dusty starbursts. As a main result, we find that dusty post-starburst galaxies
(DPSGs), with ages between 0.2 and 1 Gyr, at 1.3 < z < 2 mix with Es at 1 < z <
2 for a large range in dust amount. This ``intrusion'' is a source of concern
for the present two-colour classification of ERGs. On the other hand, we
confirm, in agreement with PM00, that DSGs are well separated from Es, both at
1 < z < 2, in the Ic-K vs. J-K colour--colour diagram, whatever the structure
(two-phase clumpy or homogeneous) of their dusty medium and their dust amount
are. This result holds under the new hypothesis of high-z Es being as dusty as
nearby ones. Thus the interpretation of the optical/near-IR colours of high-z
Es may suffer from a multiple degeneracy among age, metallicity, dust and
redshift. We also find that DPSGs at z around 1 mix with DSGs at 1 < z < 2, as
a function of dust amount and structure of the dusty medium. All these results
help explaining the complexity of the ERG classification... (Abridged)


title: IBIS/PICsIT in-flight performances

abstract:
  PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy
detector of the IBIS telescope on-board the INTEGRAL satellite. PICsIT operates
in the gamma-ray energy range between 175 keV and 10 MeV, with a typical energy
resolution of 10% at 1 MeV, and an angular resolution of 12 arcmin within a
\~100 square degree field of view, with the possibility to locate intense point
sources in the MeV region at the few arcmin level. PICsIT is based upon a
modular array of 4096 independent CsI(Tl) pixels, ~0.70 cm^2 in cross-section
and 3 cm thick. In this work, the PICsIT on-board data handling and science
operative modes are described. This work presents the in-flight performances in
terms of background count spectra, sensitivity limit, and imaging capabilities.


title:
Comment on ''The Cluster Expansion for the Self-Gravitating gas and the
  Thermodynamic Limit'', by de Vega and Sanchez (astro-ph/0307318)

abstract:
  It is shown that the argument presented in astro-ph/0307318 against the proof
that the diluted limit of a self-gravitating system is ill behaved [Nucl. Phys.
B668, 409 (2003) (astro-ph/0303301)] is misleading.


title:
SN 1994W: evidence of explosive mass ejection a few years before
  explosion

abstract:
  We present and analyse spectra of the Type IIn supernova 1994W obtained
between 18 and 202 days after explosion. During the first 100 days the line
profiles are composed of three major components: (i) narrow P Cygni lines with
absorption minima at -700 km/s; (ii) broad emission lines with BVZI ~4000 km/s;
(iii) broad wings most apparent in H-alpha. These components are identified
with the expanding circumstellar (CS) envelope (Sollerman, Cumming & Lundqvist
1998), shocked cool gas in the forward postshock region, and multiple Thomson
scattering in the CS envelope, respectively. The absence of broad P Cygni lines
from the supernova (SN) is the result of the formation of an optically thick,
cool, dense shell at the interface of the ejecta and the CS envelope. Models of
the SN deceleration and Thomson scattering wings are used to recover the
Thomson optical depth of the CS envelope and its radial extent, 4E15 cm. The
light curve, which we reproduce by a hydrodynamical model, is powered by a
combination of internal energy leakage after the explosion of an extended
presupernova (~1E15 cm) and luminosity from circumstellar interaction. We
recover the pre-explosion kinematics of the CS envelope and find it to be close
to homologous expansion with outmost velocity ~1100 km/s and a kinematic age of
\~1.5 yr. The high mass and kinetic energy of the CS envelope strongly suggest
that the CS envelope was explosively ejected only a few years before explosion.


title: Detection of the evolutionary stages of variables in M3

abstract:
  The large number of variables in M3 provides a unique opportunity to study an
extensive sample of variables with the same apparent distance modulus. Recent,
high accuracy CCD time series of the variables show that according to their
mean magnitudes and light curve shapes, the variables belong to four separate
groups. Comparing the properties of these groups (magnitudes and periods) with
horizontal branch evolutionary models, we conclude that these samples can be
unambiguously identified with different stages of the horizontal branch stellar
evolution. Stars close to the zero age horizontal branch (ZAHB) show Oosterhoff
I type properties, while the brightest stars have Oosterhoff II type statistics
regarding their mean periods and RRab/RRc number ratios. This finding
strengthens the earlier suggestion of Lee et al. (1990) connecting the
Oosterhoff dichotomy to evolutionary effects, however, it is unexpected to find
large samples of both of the Oosterhoff type within a single cluster, which is,
moreover, the prototype of the Oosterhoff I class globular clusters. The very
slight difference between the Fourier parameters of the stars (at a given
period) in the three fainter samples spanning over about 0.15 mag range in M_V
points to the limitations of any empirical methods which aim to determine
accurate absolute magnitudes of RR Lyrae stars solely from the Fourier
parameters of the light curves.


title: Shaping Planetary Nebulae and Related Objects

abstract:
  I review some open questions and other aspects concerning the shaping of
planetary nebulae (PNs) and related objects. I attribute the non-spherical
structures of PNs to binary companions, stellar or substellar. I emphasize the
role of jets (or collimated fast wind: CFW) blown by an accreting stellar
companion in shaping PNs and some related objects, and discuss the limited role
of magnetic fields. I speculate that some stars which are leaving the
asymptotic giant branch, i.e., becoming hotter, possess long-term (10-1000
years) oscillations; these may be related to semi-periodic concentric rings. I
end with a list of objects whose shaping is related to the shaping processes of
PNs, from young stellar objects to clusters of galaxies.


title: MS 1603.6+2600: an Accretion Disc Corona source?

abstract:
  We have observed the eclipsing low-mass X-ray binary MS1603.6+2600 with
Chandra for 7 ksec. The X-ray spectrum is well fit with a single absorbed
powerlaw with an index of ~2. We find a clear sinusoidal modulation in the
X-ray lightcurve with a period of 1.7+-0.2 hours, consistent with the period of
1.85 hours found before. However, no (partial) eclipses were found. We argue
that if the X-ray flare observed in earlier X-ray observations was a type I
X-ray burst then the source can only be an Accretion Disc Corona source at a
distance between ~11-24 kpc (implying a height above the Galactic disk of ~8-17
kpc). It has also been proposed in the literature that MS1603.76+2600 is a
dipper at ~75 kpc. We argue that in this dipper scenario the observed optical
properties of MS1603.6+2600 are difficult to reconcile with the optical
properties one would expect on the basis of comparisons with other high
inclination low-mass X-ray binaries, unless the X-ray flare was not a type I
X-ray burst. In that case the source can be a nearby soft X-ray transient
accreting at a quiescent rate as was proposed by Hakala et al.(1998) or a high
inclination source at ~15-20 kpc.


title:
Scale-Free Magnetic Networks: Comparing Observational Data with a
  Self-Organizing Model of the Coronal Field

abstract:
  We propose that the coronal magnetic field, linking concentrations on the
photosphere through an interwoven web of flux, embodies a scale-free network.
It arises from a self-organized critical dynamics including flux emergence, the
diffusion and merging of magnetic concentrations, as well as avalanches of
reconnecting flux tubes. Magnetic concentrations such as fragments, pores and
sunspots, are `nodes' joined by flux tubes or `links'. The number of links
emanating from a node is scale-free. We reanalyze the quiet-Sun data of Close
et al and show that the distribution of magnetic concentration strengths is a
power law with an index $\gamma= 1.7 \pm 0.3$, over the entire range of the
measurement, about $(2-500)\times 10^{17}$ Mx. This distribution is compatible
with that for the sizes of active regions reported by Harvey and Schwaan. Thus
magnetic concentrations may be scale-free from the smallest measurable
fragments to the large active regions. Numerical simulations of a
self-organized critical model give the same index $\gamma$, within statistical
uncertainty. The exponential distribution of flux tube lengths also agrees
quantitatively with results from the model. Calibration with the measured
diffusion constant of magnetic concentrations allows us to calculate a flux
turnover time in the model to be of order 10 hours and the total solar flux to
be of order $10^{23}$Mx, agreeing with observations. We introduce two other
statistical quantities to characterize scale-free networks. The probability
distribution for the amount of flux connecting a pair of concentrations, and
the number of distinct concentrations linked to a given one are predicted to be
scale-free, with different indices. Our approach unifies the observation of
scale free flare energies with the coronal magnetic field structure.


title: Explaining the High Energy Spectral Component in GRB 941017

abstract:
  The gamma-ray burst (GRB) of October 17, 1994 (941017), showed a distinct
high energy spectral component extending from $\lesssim$ a few MeV to $\gtrsim$
200 MeV, in addition to the typical GRB emission which peaked at $\lesssim$ a
few hundred keV. The high energy component carried at least $\sim$ 3 times more
energy than the lower energy component. It displayed an almost constant flux
with a rather hard spectrum ($F_\nu \propto \nu^{-\alpha}$ with $\alpha \sim
0$) from $\lesssim$ 20 s into the burst up to $\sim$ 200 s, while the duration
of the GRB, where 90% of the energy in the lower energy component was emitted,
was only 77 s. Such a high energy component was seen in only one out of $\sim$
30 GRBs in which a similar component could have been detected, and thus appears
to be quite rare. We examine possible explanations for this high energy
spectral component and find that most models fail. The only emission region
that provides the right temporal behavior is the reverse shock that goes into
the GRB ejecta as it is decelerated by the ambient medium, or possibly the very
early forward shock while the reverse shock is still going on. The best
candidate for the emission mechanism is synchrotron self-Compton emission from
the reverse shock. Even in this model the most natural spectral slope is only
marginally consistent with the observed value, and some degree of fine tuning
is required in order to improve the agreement. This might suggest that an
additional or alternative emission mechanism is at work here. A prediction of
this interpretation is that such a high energy component should be accompanied
by a bright optical transient, similar to the one observed in GRB 990123.


title: Searching for unknown open clusters in the Tycho-2 catalog

abstract:
  We present 11 new open cluster candidates found in a systematic search for
unknown star clusters using the astrometric and photometric data included in
the Tycho2 catalog. The possible existence of these stellar aggregates is
supported by the analysis of proper motions, color-magnitude diagrams, stellar
density distributions, and by the visual inspection of the Digitized Sky Survey
(DSS) plates. With these tools we were able to determine mean absolute proper
motions as well as preliminary reddenings, distances and ages for the majority
of the candidates. We found that most of them are possibly nearby (closer than
about 600 pc) open clusters never studied before.


title: Cold Dust in Kepler's Supernova Remnant

abstract:
  The timescales to replenish dust from the cool, dense winds of Asymptotic
Giant Branch stars are believed to be greater than the timescales for dust
destruction. In high redshift galaxies, this problem is further compounded as
the stars take longer than the age of the Universe to evolve into the dust
production stages. To explain these discrepancies, dust formation in supernovae
(SNe) is required to be an important process but until very recently dust in
supernova remnants has only been detected in very small quantities. We present
the first submillimeter observations of cold dust in Kepler's supernova remnant
(SNR) using SCUBA. A two component dust temperature model is required to fit
the Spectral Energy Distribution (SED) with $T_{warm} \sim 102$K and $T_{cold}
\sim 17$K. The total mass of dust implied for Kepler is $\sim 1M_{\odot}$ -
1000 times greater than previous estimates. Thus SNe, or their progenitors may
be important dust formation sites.


title:
Faint Hard X-ray Sources in the Galactic Center Region: Supernova Ejecta
  Fragments Population

abstract:
  Long Chandra observations of 17 arcmin x 17 arcmin field in the Galactic
Center (GC) region reported by Muno et. al. (2003) have revealed a population
of about 2,000 hard faint X-ray sources limited by luminosities Lx > 10(31}
erg/s. We show that fast moving knots (FMKs) of supernovae ejecta could
comprise a sizeable fraction of the sources. Each supernova event can produce
hundreds of FMKs. The presence of ~ 3 supernova remnants of age ~ 1,000 years
in the GC region could provide the required number of the FMKs. Simulated X-ray
spectra of the FMKs contain both thermal and nonthermal components. The
nonthermal spectra are power-laws with hard photon indexes 0 < Gamma < 1.5 and
prominent lines of some metals (e.g. Fe). The logN-logS distribution and the
hardness ratios of the FMKs in the GC region are consistent with the Chandra
findings. Spatial distribution of the FMKs in the GC region should appear as an
ensemble of coherent shell and jet-like structures of a few arcmin-scale.


title:
The extra-galactic Cepheid distance scale from LMC and Galactic
  period-luminosity relations

abstract:
  In this paper, we recalibrate the Cepheid distance to some nearby galaxies
observed by the HST Key Project (KP) and the Sandage-Tammann-Saha (STS) group.
We use much of the KP methodology in our analysis but apply new techniques,
based on Fourier methods to estimate the mean magnitudes to published Cepheid
data. We also apply different calibrating PL relations to estimate Cepheid
distances, and investigate the sensitivity of the distance moduli to the
adopted calibrating PL relation. We re-determine the OGLE LMC PL relations
using a more conservative approach and also study the effect of using Galactic
PL relations on the distance scale. For the KP galaxies, we find good agreement
with an average discrepancy of -0.002 and 0.075mag. when using the LMC and
Galaxy, respectively, as a calibrating PL relation. However, the Cepheid
distance to STS galaxies are shorter by -0.178mag. and -0.108mag. on average
again when using the LMC and Galaxy PL relations, respectively. We also
calculate the distance to these galaxies using PL relations at maximum light
and find very good agreement with mean light PL distances. However, after
correcting for metallicity effects, the difference between the distance moduli
obtained using the two sets of calibrating PL relations becomes negligible.
This suggests that Cepheids in the LMC and Galaxy do follow different PL
relations, at least at the median periods of the target galaxies.


title: Thermo-Hydrodynamics of Circumstellar Disks with High-mass Planets

abstract:
  With a series of numerical simulations, we analyze the thermo-hydrodynamical
evolution of circumstellar disks containing Jupiter-size protoplanets. In the
framework of the two-dimensional approximation, we consider an energy equation
that includes viscous heating and radiative effects in a simplified, yet
consistent form. Multiple nested grids are used in order to study both global
and local features around the planet. By means of different viscosity
prescriptions, we investigate various temperature regimes. A planetary mass
range from 0.1 to 1 Mj is examined. Computations show that gap formation is a
general property which affects density, pressure, temperature, optical
thickness, and radiated flux distributions. However, it remains a prominent
feature only when the kinematic viscosity is on the order of 10^(15) cm^2/s or
lower. Around accreting planets, a circumplanetary disk forms that has a
surface density profile decaying exponentially with the distance and whose mass
is 5-6 orders of magnitudes smaller than Jupiter's mass. Circumplanetary disk
temperature profiles decline roughly as the inverse of the distance from the
planet. Temperatures range from some 10 to ~1000 K. Planetary accretion and
migration rates depend on the viscosity regime, with discrepancies within an
order of magnitude. Estimates of growth and migration time scales inferred by
these models are on the same orders of magnitude as those previously obtained
with locally isothermal simulations.


title:
Neutron star mergers versus core-collapse supernovae as dominant
  r-process sites in the early Galaxy

abstract:
  The astrophysical nature of r-process sites is a long standing mystery and
many probable sources have been suggested in the past, among them lower-mass
core-collapse supernovae (in the range 8 - 10 Msol), higher-mass core-collapse
supernovae (with masses > 20 Msol) and neutron star mergers. In this work, we
present a detailed inhomogeneous chemical evolution study that considers for
the first time neutron star mergers as major r-process sources, and compare
this scenario to the ones in which core-collapse supernovae act as dominant
r-process sites. We conclude that, due to the lack of reliable iron and
r-process yields as function of progenitor mass, it is not possible at present
to distinguish between the lower-mass and higher-mass supernovae scenarios
within the framework of inhomogeneous chemical evolution. However, neutron-star
mergers seem to be ruled out as the dominant r-process source, since their low
rates of occurrence would lead to r-process enrichment that is not consistent
with observations at very low metallicities. Additionally, the considerable
injection of r-process material by a single neutron-star merger leads to a
scatter in [r-process/Fe] ratios at later times which is much too large
compared to observations.


title: Large-scale structure and matter in the universe

abstract:
  This paper summarizes the physical mechanisms that encode the type and
quantity of cosmological matter in the properties of large-scale structure, and
reviews the application of such tests to current datasets. The key lengths of
the horizon size at matter-radiation equality and at last scattering determine
the total matter density and its ratio to the relativistic density; acoustic
oscillations can diagnose whether the matter is collisionless, and small-scale
structure or its absence can limit the mass of any dark-matter relic particle.
The most stringent constraints come from combining data on present-day galaxy
clustering with data on CMB anisotropies. Such an analysis breaks the
degeneracies inherent in either dataset alone, and proves that the universe is
very close to flat. The matter content is accurately consistent with pure Cold
Dark Matter, with about 25% of the critical density, and fluctuations that are
scalar-only, adiabatic and scale-invariant. It is demonstrated that these
conclusions cannot be evaded by adjusting either the equation of state of the
vacuum, or the total relativistic density.


title: IBIS performances during the Galactic Plane Scan - I. The Cygnus region

abstract:
  The Plane of our Galaxy is regularly observed by the INTEGRAL satellite by
means of scheduled scans. We present here results from the IBIS/ISGRI
instrument using data from the first two Galactic Plane Scans performed at the
end of the Performance Verification phase, while INTEGRAL was pointed towards
the Cygnus region.
  Considering the predicted IBIS sensitivity, we expected three persistent
sources to be detectable: Cyg X--1, Cyg X--3, Cyg X--2, in order of decreasing
intensity in the hard-X energy range (>15 keV). In addition to these sources,
our analysis revealed two more transient sources, confirming the unprecedented
IBIS sensitivity. For each exposure (~2200 s) of the two scans, we report on
detected source fluxes, variabilities and localisation accuracies.


title: Large-scale surveys and cosmic structure

abstract:
  These lectures deal with our current knowledge of the matter distribution in
the universe, focusing on how this is studied via the large-scale structure
seen in galaxy surveys. We first assemble the necessary basics needed to
understand the development of density fluctuations in an expanding universe,
and discuss how galaxies are located within the dark-matter density field.
Results from the 2dF Galaxy Redshift Survey are presented and contrasted with
theoretical models. We show that the combination of large-scale structure and
data on microwave-background anisotropies can eliminate almost all
degeneracies, and yield a completely specified cosmological model. This is the
"concordance" universe: a geometrically flat combination of vacuum energy and
cold dark matter. The study of cosmic structure is able to establish this in a
manner independent of external information, such as the Hubble diagram; this
extra information can however be used to limit non-standard alternatives, such
as a variable equation of state for the vacuum.


title:
Influences of neutron star parameters on evolutions of different types
  of pulsar; evolutions of anomalous X-ray pulsars, soft gamma repeaters and
  dim isolated thermal neutron stars on the P-\.{P} diagram

abstract:
  Influences of the mass, moment of inertia, rotation, absence of stability in
the atmosphere and some other parameters of neutron stars on the evolution of
pulsars are examined. It is shown that the locations and evolutions of soft
gamma repeaters, anomalous X-ray pulsars and other types of pulsar on the
period versus period derivative diagram can be explained adopting values of
B$<10^{14}$ G for these objects. This approach gives the possibility to explain
many properties of different types of pulsar.


title: Universal spectral shape of high accretion rate AGN

abstract:
  The spectra of quasars and NLS1 galaxies show surprising similarity in their
spectral shape. They seem to scale only with the accretion rate. This is in
contradiction with the simple expectations from the standard disk model which
predicts lower disk temperature for higher black hole mass. Here we consider
two mechanisms modifying the disk spectrum: the irradiation of the outer disk
due to the scattering of the flux by the extended ionized medium (warm absorber
and the development of the warm Comptonizing disk skin under the effect of the
radiation pressure instability. Those two mechanisms seem to lead to a spectrum
which indeed roughly scales, as observed, only with the accretion rate. The
scenario applies only to objects with relatively high luminosity to the
Eddington luminosity ratio for which disk evaporation is inefficient.


title: Major Mergers of Galaxy Haloes: Cuspy or Cored Inner Density Profile?

abstract:
  We present the results from a series of collisionless N-body simulations of
major mergers of galaxy dark matter haloes with density profiles having either
inner cusps or cores. Our simulations range from 2x10^5 to 10^7 particles,
allowing us to probe the phase-space distribution of dark matter particles in
the innermost regions (less than 0.005 virial radii) of cold dark matter
haloes, a subject of much recent debate. We find that a major merger of two
cored haloes yields a cored halo and does not result in a cuspy profile seen in
many cosmological simulations. This result is unchanged if we consider mergers
with parent mass ratios of 3:1 instead of 1:1. Mergers of a cuspy halo with
either a cored halo or a second cuspy halo of equal mass, on the other hand,
produce cuspy haloes with a slightly reduced inner logarithmic slope. Cuspy
haloes, once formed, therefore appear resilient to major mergers. We find the
velocity structure of the remnants to be mildly anisotropic, with a Maxwellian
velocity distribution near the centre but not in the outer portions of the
final haloes. Violent relaxation is effective only during the early phase of
mergers, with phase mixing likely to be the dominant relaxation process at late
times.


title: On the formation of the Magellanic Stream

abstract:
  We use high resolution N-Body/SPH simulations to study the hydro-dynamical
and gravitational interaction between the Large Magellanic Cloud and the Milky
Way. We model the dark and hot extended halo components as well as the
stellar/gaseous disks of the two galaxies. Tidal forces distort the LMC's disk,
forcing a bar and creating a diffuse stellar halo and a strong warp, although
very few stars are unbound from the LMC. Ram-pressure from a low density
ionised halo is then sufficient to remove $1.4 \times 10^8M_\odot$ of gas from
the LMC's disk forming a great circle trailing stream around the Galaxy.


title: Cooling in Coronal Gas in the M82 Starburst Superwind

abstract:
  We have used the Far Ultraviolet Spectroscopic Explorer to search for OVI
1031.926 Angstrom emission at four locations in the starburst superwind of M82.
No OVI emission was detected at any of the four pointings, with upper limits
less than or equal to the 0.3-2 keV X-ray flux. These observations limit the
energy lost through radiative cooling of coronal phase (T~300,000 K) gas to
roughly the same magnitude as that lost in the hot phase through X-ray
emission, which has been shown to be small. The wind material retains most of
its energy and should be able to escape from the gravitational potential of
M82, enriching the intergalactic medium with energy and metals. The lack of
coronal gas in the wind and observations of spatially correlated X-ray and
H-alpha emission are consistent with a scenario in which the hot wind material
over-runs cold clouds in the halo, or one where the H-alpha and X-ray emission
arise at the interface between the hot wind and a cool shell of swept-up ISM,
as long as the shock velocity is <150 km/s. The observed limits on the
OVI/H-alpha and CIII/H-alpha flux ratios rule out shock heating as the source
of the 10,000 K gas unless the shock velocity is <90 km/s.


title: Lyman-break galaxies: high mass or low?

abstract:
  We reassess the hypothesis that Lyman-break galaxies (LBGs) at redshifts z~3
mark the centres of the most massive dark matter haloes at that epoch. First we
reanalyse the kinematic measurements of Pettini et al., and of Erb et al., of
the rest-frame optical emission lines of LBGs. We compare the distribution of
the ratio of the rotation velocity to the central line width, against the
expected distribution for galaxies with random inclination angles, modelled as
singular isothermal spheres. The model fits the data well. On this basis we
argue that the central line width provides a predictor of the circular velocity
at a radius of several kpc. Assembling a larger sample of LBGs with measured
line widths, we compare these results against the theoretical Lambda-CDM
rotation curves of Mo, Mao & White, under the hypothesis that LBGs mark the
centres of the most massive dark matter halos. We find that the circular
velocities are over-predicted by a substantial factor, which we estimate
conservatively as 1.8+/-0.4. This indicates that the model is probably
incorrect. The model of LBGs as relatively low-mass starburst systems, of
Somerville, Primack, and Faber (2001), provides a good fit to the data.


title: Particle Pile-ups and Planetesimal Formation

abstract:
  Solid particles in protoplanetary disks that are sufficiently super-solar in
metallicity overcome turbulence generated by vertical shear to gravitationally
condense into planetesimals. Super-solar metallicities result if solid
particles pile up as they migrate starward as a result of aerodynamic drag.
Previous analyses of aerodynamic drift rates that account for mean flow
differences between gas and particles yield particle pile-ups. We improve on
these studies not only by accounting for the collective inertia of solids
relative to that of gas, but also by including the transport of angular
momentum by turbulent stresses within the particle layer. These turbulent
stresses are derived in a physically self-consistent manner from the structure
of marginally Kelvin-Helmholtz turbulent flows. They are not calculated using
the usual plate drag formulae, whose use we explain is inappropriate.
Accounting for the relative inertia of solids to gas retards, but does not
prevent, particle pile-ups, and generates more spatially extended regions of
metal enrichment. Turbulent transport hastens pile-ups. We conclude that
particle pile-up is a robust outcome in sufficiently passive protoplanetary
disks. Connections to observations of circumstellar disks, including the Kuiper
Belt, and the architectures of planetary systems are made.


title: Three-Dimensional Dynamics of Narrow Planetary Rings

abstract:
  Narrow planetary rings are eccentric and inclined. Particles within a given
ring must therefore share the same pericenter and node. We solve for the
three-dimensional geometries and mass distributions that enable the Uranian
Alpha and Beta rings, and the Saturnian Maxwell and Colombo (Titan) rings, to
maintain simultaneous apsidal and nodal lock. Ring self-gravity, interparticle
collisions, and the quadrupole field of the host planet balance each other to
achieve this equilibrium. We prove that such an equilibrium is linearly stable.
Predictions for the Saturnian ringlets to be tested by the Cassini spacecraft
include: (1) ringlet masses are of order 1e19 g, (2) surface mass densities
should increase from ring midline to ring edges, and (3) rings are vertically
warped such that the fractional variation of inclination across the ring is of
order 10%. Analogous predictions are made for the Uranian rings. Simultaneous
apsidal and nodal locking forces the narrowest portion of the ring--its
``pinch,'' where self-gravitational and collisional forces are strongest--to
circulate relative to the node, and introduces previously unrecognized
time-varying forces perpendicular to the planet's equator plane. We speculate
that such periodic stressing might drive kilometer-scale bending waves at a
frequency twice that of apsidal precession. Such flexing might be observed over
a few weeks by Cassini.


title: Dust in Protoplanetary Disks

abstract:
  We critically examine the best lines of evidence for grain growth in
protoplanetary disks, based on modelling of observed spectral energy
distributions and images of T Tauri and Herbig Ae stars. The data are
consistent with millimeter-sized grains near disk midplanes, and micron-sized
grains near disk surfaces. We review three channels by which grains can grow,
including direct condensation from the vapor phase, grain-grain collisional
sticking, and gravitational instability. The utility of dust in identifying as
yet unseen extrasolar planets is highlighted.


title: Resonant and Secular Families in the Kuiper Belt

abstract:
  We review ongoing efforts to identify occupants of mean-motion resonances
(MMRs) and collisional families in the Edgeworth-Kuiper belt. Direct
integrations of trajectories of Kuiper belt objects (KBOs) reveal the 1:1
(Trojan), 5:4, 4:3, 3:2 (Plutino), 5:3, 7:4, 9:5, 2:1 (Twotino), and 5:2 MMRs
to be inhabited. Apart from the Trojan, resonant KBOs typically have large
orbital eccentricities and inclinations. The observed pattern of resonance
occupation is consistent with resonant capture and adiabatic excitation by a
migratory Neptune; however, the dynamically cold initial conditions prior to
resonance sweeping that are typically assumed by migration simulations are
probably inadequate. Given the dynamically hot residents of the 5:2 MMR and the
substantial inclinations observed in all exterior MMRs, a fraction of the
primordial belt was likely dynamically pre-heated prior to resonance sweeping.
A pre-heated population may have arisen as Neptune gravitationally scattered
objects into trans-Neptunian space. The spatial distribution of Twotinos offers
a unique diagnostic of Neptune's migration history. The Neptunian Trojan
population may rival the Jovian Trojan population, and the former's existence
is argued to rule out violent orbital histories for Neptune. Finally,
lowest-order secular theory is applied to several hundred non-resonant KBOs
with well-measured orbits to update proposals of collisional families. No
convincing family is detected.


title: Procedures, Resources, and Selected Results of the Deep Ecliptic Survey

abstract:
  The Deep Ecliptic Survey is a project whose goal is to survey a large area of
the near-ecliptic region to a faint limiting magnitude (R ~ 24) in search of
objects in the outer solar system. We are collecting a large homogeneous data
sample from the Kitt Peak Mayall 4-m and Cerro Tololo Blanco 4-m telescopes
with the Mosaic prime-focus CCD cameras. Our goal is to collect a sample of 500
objects with good orbits to further our understanding of the dynamical
structure of the outer solar system. This survey has been in progress since
1998 and is responsible for 272 designated discoveries as of March 2003. We
summarize our techniques, highlight recent results, and describe publically
available resources.


title:
A Re-examination of the $^{187}$Re Bound on the Variation of Fundamental
  Couplings

abstract:
  We reconsider the Re187 bound on the variation of the fine-structure
constant. We combine the meteoritic measurement with several present-day lab
measurements to firmly establish the quantitative upper limit to the time
variation over the age of the solar system. We find that the relative change of
the fine-structure constant between its present value and $\alpha$ of \sim 4.6
Gyr ago is consistent with zero, Delta alpha/alpha = [-8\pm 8 (1\sigma)] x
10^{-7}.
  We also rederive this bound in models where all gauge and Yukawa couplings
vary in an interdependent manner, as would be expected in unified theories.


title:
Non-Nuclear Hyper/Ultraluminous X-Ray Sources in the Starbursting
  Cartwheel Ring Galaxy

abstract:
  We report the Chandra/ACIS-S detection of more than 20 ultraluminous X-ray
sources (ULXs, L_{0.5-10 keV} >~ 3 x 10^{39} ergs/sec) in the Cartwheel
collisional ring galaxy system, of which over a dozen are located in the outer
active star-forming ring. A remarkable hyperluminous X-ray source (HLX,
L_{0.5-10 keV} >~ 10^{41} ergs/sec assuming isotropic radiation), which
dominates the X-ray emission from the Cartwheel ring, is located in the same
segment of the ring as most ULXs. These powerful H/ULXs appear to be coincident
with giant HII region complexes, young star clusters, and radio and
mid-infrared hot-spots: all strong indicators of recent massive star formation.
The X-ray spectra show that H/ULXs have similar properties as those of the {\it
most luminous} ULXs found in the nearest starbursts and galaxy mergers such as
the Antennae galaxies and M82. The close association between the X-ray sources
and the starbursting ring strongly suggests that the H/ULXs are intimately
associated with the production and rapid evolution of short-lived massive
stars. The observations represent the most extreme X-ray luminosities
discovered to date associated with star-forming regions--rivaling the X-ray
luminosities usually associated with active galactic nuclei.


title: Andromeda VIII - a New Tidally Distorted Satellite of M31

abstract:
  We report the detection of a new satellite of M31, projected close to M32.
And VIII is tidally distorted, with length ~10 kpc and width a few kpc. It
contains 5-12 planetary nebulae (PNe) and 1-3 globular clusters, and has a
velocity of -204 km/s with respect to M31, some 350 km/s away from M32's
velocity. There are also about 4 x 10^5 solar masses of HI, well-separated from
the disk, at the same position and velocity. The satellite has luminosity of
1.2-2.4 x 10^8 solar luminosities, and a central surface brightness of order
\mu_V=24. Both these values are typical of Local Group dwarf galaxies. Its
surface brightness is some 6 magnitudes brighter than any of the stellar
streams found in the Milky Way or M31. The three associated globular clusters
have reddening consistent with foreground reddening from the Milky Way only,
making it likely that the satellite is in front of M31, unlike the giant tidal
stream of Ibata et al.(2001), which is behind M31 in the SE quadrant. However,
the major axis of And VIII is aligned with the western edge of this giant
stream, and we suggest that its unusual fan shape is caused by superposition of
two streams, the westernmost of which was tidally stripped from And VIII.


title: D/H as a Measure of Chemical Imhomogeneity in our Galaxy

abstract:
  Accurate measurements of interstellar deuterium abundances along lines of
sight extending out to several hundred parsecs by FUSE and other instruments is
making D/H a useful tool for understanding Galactic chemical evolution. We find
that the gas inside of the Local Bubble is chemically homogeneous, but that
large variations in D/H beyond the Local Bubble are real and challenge present
concepts of chemical evolution. A new set of models is needed that will include
spatially dependent infall of relatively unprocessed material, depletion of D
onto grains, and appropriate mixing timescales. $


title: Epsilon Indi Ba/Bb: the nearest binary brown dwarf

abstract:
  We have carried out high angular resolution near-infrared imaging and
low-resolution (R~1000) spectroscopy of the nearest known brown dwarf, Eps Indi
B, using the ESO VLT NAOS/CONICA adaptive optics system. We find it to be a
close binary (as also noted by Volk et al. 2003) with an angular separation of
0.732 arcsec, corresponding to 2.65AU at the 3.626pc distance of the Eps Indi
system. In our discovery paper (Scholz et al. 2003), we concluded that Eps Indi
B was a ~50Mjup T2.5 dwarf: our revised finding is that the two system
components (Eps Indi Ba and Eps Indi Bb) have spectral types of T1 and T6,
respectively, and estimated masses of 47 and 28Mjup, respectively, assuming an
age of 1.3Gyr. Errors in the masses are +/-10 and +/-7Mjup, respectively,
dominated by the uncertainty in the age determination (0.8-2Gyr range). This
uniquely well-characterised T dwarf binary system should prove important in the
study of low-mass, cool brown dwarfs. The two components are bright and
relatively well-resolved: Eps Indi B is the only T dwarf binary in which
spectra have been obtained for both components. They have a well-established
distance and age. Finally, their orbital motion can be measured on a fairly
short timescale (nominal orbital period 15 yrs), permitting an accurate
determination of the true total system mass, helping to calibrate brown dwarf
evolutionary models.


title:
The NIRSPEC Brown Dwarf Spectroscopic Survey. I. Low-Resolution
  Near-Infrared Spectra

abstract:
  We present the first results of a near-infrared (0.96-2.31 micron)
spectroscopic survey of M, L, and T dwarfs obtained with NIRSPEC on the Keck II
telescope. Our new survey has a resolving power of R = 2000 and is comprised of
two major data sets: 53 J-band (1.14-1.36 micron) spectra covering all spectral
types from M6 to T8 with at least two members in each spectral subclass
(wherever possible), and 25 flux-calibrated spectra from 1.14 to 2.31 microns
for most spectral classes between M6 and T8. Sixteen of these 25 objects have
additional spectral coverage from 0.96-1.14 microns to provide overlap with
optical spectra. Spectral flux ratio indexes for prominent molecular bands are
derived and equivalent widths (EWs) for several atomic lines are measured. We
find that a combination of four H2O and two CH4 band strengths can be used for
spectral classification. Weak (EW~1-2 angstrom) atomic lines of Al I and Ca I
disappear at the boundary between M and L types.