title:
3 - 14 Micron Spectroscopy of Comets C/2002 O4 (Honig), C/2002 V1
  (NEAT), C/2002 X5 (Kudo-Fujikawa), C/2002 Y1 (Juels-Holvorcem), 69P/Taylor,
  and the Relationships among Grain Temperature, Silicate Band Strength and
  Structure among Comet Families

abstract:
  We report 3 - 13 micron spectroscopy of 4 comets observed between August 2002
and February 2003: C/2002 O4 (Honig) on August 1, 2002, C/2002 V1 (NEAT) on
Jan. 9 and 10, 2003, C/2002 X5 (Kudo-Fujikawa) on Jan. 9 and 10, 2003, and
C/2002 Y1 (Juels-Holvorcem) on Feb. 20, 2003. In addition, we include data
obtained much earlier on 69P/Taylor (February 9, 1998) but not previously
published. For Comets Taylor, Honig, NEAT, and Kudo-Fujikawa, the silicate
emission band was detected, being approximately 23%, 12%, 15%, and 10%,
respectively, above the continuum. The data for Comet Juels-Holvorcem were of
insufficient quality to detect the presence of a silicate band of comparable
strength to the other three objects, and we place an upper limit of 24% on this
feature. The silicate features in both NEAT and Kudo-Fujikawa contained
structure indicating the presence of crystalline material. Combining these data
with those of other comets, we confirm the correlation between silicate band
strength and grain temperature of Gehrz & Ney (1992) and Williams et al. (1997)
for dynamically new and long period comets, but the majority of Jupiter family
objects may deviate from this relation. The limited data available on Jupiter
family objects suggest that they may have silicate bands that are slightly
different from the former objects. Finally, when compared to the silicate
emission bands observed in pre-main sequence stars, the dynamically new and
long period comets most closely resemble the more evolved stellar systems,
while the limited data (in quantity and quality) on Jupiter family objects seem
to suggest that these have spectra more like the less-evolved stars.


title:
The Formation of a Helium White Dwarf in Close Binary System with
  Diffusion

abstract:
  We study the evolution of a system composed by a 1.4 \msun neutron star and a
normal, solar composition star of 2 \msun in orbit with a period of 1 day.
Calculations were performed employing the binary hydro code presented in
Benvenuto & De Vito (2003) that handle the mass transfer rate in a fully
implicit way. Now we included the main standard physical ingredients together
with diffusion processes and a proper outer boundary condition. We have assumed
fully non - conservative mass transfer episodes.
  In order to study the interplay of mass loss episodes and diffusion we
considered evolutionary sequences with and without diffusion in which all Roche
lobe overflows (RLOFs) produce mass transfer. Another two sequences in which
thermonuclearly-driven RLOFs are not allowed to drive mass transfer have been
computed with and without diffusion. To our notice, this study represents the
first binary evolution calculations in which diffusion is considered.
  The system produces a helium white dwarf of \sim 0.21 \msun in an orbit with
a period of \sim 4.3 days for the four cases. We find that mass transfer
episodes induced by hydrogen thermonuclear flashes drive a tiny amount of mass
transfer. As diffusion produces stronger flashes, the amount of hydrogen - rich
matter transferred is slightly higher than in models without diffusion.
  We find that diffusion is the main agent in determining the evolutionary
timescale of low mass white dwarfs even in presence of mass transfer episodes.


title: IR Surface Brightness Fluctuations of Magellanic Star Clusters

abstract:
  We present surface brightness fluctuations (SBFs) in the near--IR for 191
Magellanic star clusters available in the Second Incremental and All Sky Data
releases of the Two Micron All Sky Survey (2MASS), and compare them with SBFs
of Fornax Cluster galaxies and with predictions from stellar population models.
Our goals are twofold. First, to provide an empirical calibration of near--IR
SBFs, given that existing stellar population synthesis models are particularly
discrepant in the near--IR. Second, whereas most previous SBF studies have
focused on old, metal rich populations, this is the first application to a
system with such a wide range of ages (~ 10^6 to more than 10^10 yr, i.e., 4
orders of magnitude), at the same time that the clusters have a very narrow
range of metallicities (Z ~ 0.0006 -- 0.01, ie., 1 order of magnitude only).
Since stellar population synthesis models predict a more complex sensitivity of
SBFs to metallicity and age in the near--IR than in the optical, this analysis
offers a unique way of disentangling the effects of age and metallicity. We
find a satisfactory agreement between models and data. We also confirm that
near--IR fluctuations and fluctuation colors are mostly driven by age in the
Magellanic cluster populations, and that in this respect they constitute a
sequence in which the Fornax Cluster galaxies fit adequately. Moreover,
fluctuation colors display a tendency to redden with age that can be fit by a
straight line. Finally, we use for the first time a Poissonian approach to
establish the error bars of the fluctuation measurements, instead of the
customary Monte Carlo simulations.


title:
Wind-Wind Collision in the eta Carinae Binary System: a Shell-Like Event
  Near Periastron

abstract:
  The exact nature of eta Carinae is still an open issue. In this paper we
assume a binary system to explain the strong X-ray emission, but we also take
into account that, near periastron and because of the highly eccentric orbit,
the wind emerging from eta Carinae accumulates behind the shock and can mimic a
shell-like ejection event. For this process to be effective, at periastron the
secondary star should be located between eta Carinae and the observer, solving
also the discrepancy between the orbital parameters derived from ground and
space based observations. We show that, as the secondary moves in its orbit,
the shell cools down and the number of available stellar ionizing photons is
not enough to maintain the shell temperature at its equilibrium value of about
7500 K. The central part of the shell remains cold and under these conditions
grain formation and growth can take place in timescales of hours. Using
recently published HST data for the optical and UV continuum during the 2003
shell event, we estimated that a fraction of 0.01 of the interstellar dust to H
ratio is enough to explain the observations. We also calculated the neutral gas
column density intercepting the line of sight at each point of the orbit near
periastron, and were able to reproduce the form and duration of the X-ray light
curve without any change in the eta Carinae mass loss rate. This same column
density can explain the observed H$\alpha$ light curve observed during the 2003
event.


title: A broad iron K alpha line at z=1.146

abstract:
  We report the discovery of a strong iron K alpha line in the hard X-ray
selected source CXOJ 123716.7+621733 in the Chandra Deep Field North survey at
z=1.146. The analysis is made possible by the very deep exposure ~2 Ms and low
background of the ACIS detector. The line profile seems to be inconsistent with
a narrow feature. The best fit solution is achieved with a broad line. Most of
the flux in the broad component originates at energies below 6.4 keV with a
shape similar to that expected from emission in the innermost regions of the
accretion disk.


title:
The Pattern Speeds of M51, M83 and NGC 6946 Using CO and the
  Tremaine-Weinberg Method

abstract:
  In spiral galaxies where the molecular phase dominates the ISM, the molecular
gas as traced by CO emission will approximately obey the continuity equation on
orbital timescales. The Tremaine-Weinberg method can then be used to determine
the pattern speed of such galaxies. We have applied the method to single-dish
CO maps of three nearby spirals, M51, M83 and NGC 6946 to obtain estimates of
their pattern speeds: 38 +/- 7 km/s/kpc, 45 +/- 8 km/s/kpc and 39 +/- 8
km/s/kpc, respectively, and we compare these results to previous measurements.
We also analyze the major sources of systematic errors in applying the
Tremaine-Weinberg method to maps of CO emission.


title:
A Search for Arrival Direction Clustering in the HiRes-I Monocular Data
  above 10^(19.5) eV

abstract:
  In the past few years, small scale anisotropy has become a primary focus in
the search for source of Ultra-High Energy Cosmic Rays (UHECRs). The Akeno
Giant Air Shower Array (AGASA) has reported the presence of clusters of event
arrival directions in their highest energy data set. The High Resolution Fly's
Eye (HiRes) has accumulated an exposure in one of its monocular eyes at
energies above 10^(19.5) eV comparable to that of AGASA. However, monocular
events observed with an air fluorescence detector are characterized by highly
asymmetric angular resolution. A method is developed for measuring
autocorrelation with asymmetric angular resolution. It is concluded that
HiRes-I observations are consistent with no autocorrelation and that the
sensitivity to clustering of the HiRes-I detector is comparable to that of the
reported AGASA data set. Furthermore, we state with a 90% confidence level that
no more than 13% of the observed HiRes-I events above 10^(19.5) eV could be
sharing common arrival directions. However, because a measure of
autocorrelation makes no assumption of the underlying astrophysical mechanism
that results in clustering phenomena, we cannot claim that the HiRes monocular
analysis and the AGASA analysis are inconsistent beyond a specified confidence
level.


title:
Central Stars of Planetary Nebulae in the Large Magellanic Cloud: A
  Far-UV Spectroscopic Analysis

abstract:
  We observed seven central stars of planetary nebulae (CSPN) in the Large
Magellanic Cloud (LMC) with the Far Ultraviolet Spectroscopic Explorer (FUSE),
and performed a model-based analysis of these spectra in conjunction with
Hubble Space Telescope (HST) spectra in the UV and optical range to determine
the stellar and nebular parameters. Most of the objects show wind features, and
they have effective temperatures ranging from 38 to 60 kK with mass-loss rates
of ~= 5x10^-8 Msun/yr. Five of the objects have typical LMC abundances. One
object (SMP LMC 61) is a [WC4] star, and we fit its spectra with He/C/O-rich
abundances typical of the [WC] class, and find its atmosphere to be
iron-deficient. Most objects have very hot (T ~> 2000 K) molecular hydrogen in
their nebulae, which may indicate a shocked environment. One of these (SMP LMC
62) also displays OVI 1032-38 nebular emission lines, rarely observed in PN.


title: Theoretical Aspects of Gamma-Ray Bursts

abstract:
  Cosmological GRBs are discussed with an emphasis on their plausible
connection with black holes. GRBs can be triggered by collapse of stellar-mass
objects that leads to formation of a black hole and a transient debris disk
with a huge accretion rate. The disk is believed to produce a relativistic jet
(``fireball'') that expands and emits to infinity the observed burst of
gamma-rays. This accretion-jet picture is similar to quasars and X-ray
binaries, however, there are important differences: the physical conditions and
the cooling mechanism in the disk are very different. The observed radiation is
emitted when the expanding fireball becomes transparent, at distances much
larger than the Schwarzschild radius. The burst is then observed as a powerful
relativistic explosion and the transient accretion disk in its center serves as
a brief source of energy that drives the explosion. The explosion picture
depends on the fireball nuclear composition which is shaped close to the black
hole. A large amount of free neutrons survive till the emission phase and link
the physics of the central engine to observed radiation.


title:
A VLA Search for Water Masers in Six HII Regions: Tracers of Triggered
  Low-Mass Star Formation

abstract:
  We present a search for water maser emission at 22 GHz associated with young
low-mass protostars in six HII regions -- M16, M20, NGC 2264, NGC 6357, S125,
and S140. The survey was conducted with the NRAO Very Large Array from 2000 to
2002. For several of these HII regions, ours are the first high-resolution
observations of water masers. We detected 16 water masers: eight in M16, four
in M20, three in S140, and one in NGC 2264. All but one of these were
previously undetected. No maser emission was detected from NGC 6357 or S125.
There are two principle results to our study. (1) The distribution of water
masers in M16 and M20 does not appear to be random but instead is concentrated
in a layer of compressed gas within a few tenths of a parsec of the ionization
front. (2) Significantly fewer masers are seen in the observed fields than
expected based on other indications of ongoing star formation, indicating that
the maser-exciting lifetime of protostars is much shorter in HII regions than
in regions of isolated star formation. Both of these results confirm
predictions of a scenario in which star formation is first triggered by shocks
driven in advance of ionization fronts, and then truncated approximately 10^5
years later when the region is overrun by the ionization front.


title: Covariant Analysis of Experimental Constraints on the Brane-world

abstract:
  Some observational constraints on the brane-world based on predictions from
specific models in five dimensions, have been recently reported, both on local
and cosmological scales. In order to identify the origins of these constraints,
the equations of motion of the brane-world are translated to the most general,
model-independent (or "covariant"), formulation of the theory, based only on
the Einstein-Hilbert action for the bulk geometry, the confinement of the
standard gauge interactions and the exclusive probing of the extra dimensions
by the gravitational field. In the case of the binary pulsar PSR1913+16, it is
found that gravi-vectors and gravi-scalars do not appear in the covariant
equations, but they are replaced by vector and scalar fields related to the
extrinsic curvature of the brane-world. Only the latter one impose a condition
on the binary pulsar orbits. A general solution for this problem is proposed,
based on results from differential geometry, suggesting a stable bulk geometry,
whose existence requires higher dimensions. On the cosmological scale, it is
shown that the high energy inflation constraint originating from the square of
the energy density term in the modified Friedman's equation is mainly due to
the assumption of the reflection symmetry across the brane-world. It is shown
that this symmetry is not consistent with the regularity of the brane-world.
These results suggest that the two constraints can be lifted by increasing the
number of extra dimensions.


title: In Quest of a True Model of the Universe

abstract:
  While many observations support the validity of Einstein's general relativity
as the theory of gravity, there are yet many that suggest the presence of new
physics. In order to explain the high-redshift supernovae Ia observations
together with the recently made precise observations of the CMB anisotropy by
WMAP, the standard cosmology has to invoke some hypothetical matter with
unnatural properties which is very speculative. This casts doubts upon the
foundations of the standard cosmology and suggests that some theoretical
concept may still be missing from the theory.
  Such a concept might be the rotation of the astronomical objects, which has
not been properly taken care of when we claim that a perfect fluid is a good
approximation to the real contents of the universe. A crude estimation of the
angular kinetic energy of massive galaxies indicates to a possibility to have
$\Omega_{\rm total}\approx 1$ without invoking the hypothetical dark matter or
dark energy. This picture also appears consistent with the recent observations
of a great abundance of old massive galaxies made by Gemini Deep Deep Survey.
However, a proper relativistic theory of the rotating objects is still to be
investigated. It is expected that the consequences of incorporating rotation in
general relativity, and hence in special relativity, would be profound.


title: Blue colours of BL Lac host galaxies

abstract:
  Near-infrared and optical imaging of BL Lac host galaxies is used to
investigate their colour properties. We find that the R-H colour and colour
gradient distributions of the BL Lac hosts are much wider than those for normal
ellipticals, and many objects have very blue hosts and/or steep colour
gradients. The blue colours are most likely caused by recent star formation.
The lack of obvious signs of interaction may, however, require a significant
time delay between the interaction event with associated star formation
episodes and the onset of the nuclear activity.


title:
A new sample of large angular size radio galaxies. III. Statistics and
  evolution of the grown population

abstract:
  We present in this paper a detailed study of a new sample of large angular
size FR I and FR II radio galaxies and compare the properties of the two
classes. As expected, a pure morphology based distinction of FR Is and FR IIs
corresponds to a break in total radio power. The radio cores in FR Is are also
weaker than in FR IIs, although there is not a well defined break power. We
find that asymmetry in the structure of the sample members must be the
consequence of anisotropies in the medium where the lobes expand, with
orientation playing a minor role. Moreover, literature data and our
observations at kiloparsec scales suggest that the large differences between
the structures of FR I and FR II radio galaxies must arise from the poorly
known central kiloparsec region of their host galaxies. We analyze the
sub-sample of giant radio galaxies, and do not find evidence that these large
objects require higher core powers. Our results are consistent with giant radio
galaxies being the older population of normal FR I and FR II objects evolving
in low density environments. Comparing results from our sample with predictions
from the radio luminosity function we find no evidence of a possible FR II to
FR I evolution. Moreover, we conclude that at z~0.1, one out of four FR II
radio sources has a linear size above 500 kpc, thus being in an advanced stage
of evolution (for example, older than ~10 Myr assuming a jet-head velocity of
0.1c). Radio activity seems to be a short-lived process in active galaxies,
although in some cases recurrent: five objects in our sample present signs of
reactivation in their radio structures.


title: Dominant galaxies in 2dF groups

abstract:
  We investigate whether the spectral-type of a locally dominant (most
luminous) galaxy can be used to select sets of galaxies that are physically
associated (groups). We assume that passive dominants trace a group-like
potential, and SF-dominants a field-like environment. The group sample includes
988 groups selected in the 2dFGRS applying a maximum magnitude difference
criterion. We find that the average number of passive galaxies associated to a
dominant is larger when the dominant is passive, a result supporting our
assumption that galaxy associations around a passive dominant are reliable
groups. Finally we show that, to reduce the contamination by unbound galaxy
associations (SF-dominant), a >=3 passive-members criterion is more efficient
than a >=6 all-members criterion.


title:
A study of diffusive shock acceleration as a process explaining
  observations of 1 E0657-56 galaxy cluster

abstract:
  Chandra X-ray observations of the 1 E0657-56 galaxy cluster diffuse emission
reveal the existence of large scale cluster merger shock. We study the observed
radio and X-ray data of this cluster as a possible result of the diffusive
shock acceleration. This model can explain the observations within reasonable
ranges of physical parameters for the shock and the intracluster medium. The
expected nonthermal soft and hard X-ray fluxes are predicted.


title:
Evolution of planetary nebulae II. Population effects on the bright
  cut-off of the PNLF

abstract:
  We investigate the bright cut-off of the [OIII]l5007 planetary nebula
luminosity function (PNLF), that has been suggested as a powerful extragalactic
distance indicator. Theoretical PNLFs are constructed via Monte-Carlo
simulations of populations of PNe, whose individual properties are described
with the aid of recent PN synthetic models (Marigo et al. 2001), coupled to a
detailed photoionisation code (CLOUDY). The basic dependences of the cut-off
magnitude M* are then discussed. We find that: (i) In galaxies with recent or
ongoing star formation, the modelled PNLF present M* values between -4 and -5,
very close to the observationally-calibrated value for the LMC. (ii) In these
galaxies, the PNLF cut-off is produced by PNe with progenitor masses of about
2.5 Msun, while less massive stars give origin to fainter PNe. As a consequence
M* is expected to depend strongly on the age of the last burst of star
formation, dimming by as much as 5 mag as we go from young to 10-Gyr old
populations. (iii) Rather than on the initial metallicity of a stellar
population, M* depends on the actual [O/H] of the observed PNe, a quantity that
may differ significantly from the initial value (due to dredge-up episodes),
especially in young and intermediate-age PN populations. (iv) Also the
transition time from the end of AGB to the PN phase, and the nuclear-burning
properties (i.e. H- or He-burning) of the central stars introduce
non-negligible effects on M*. The strongest indication derived from the present
calculations is a serious difficulty to explain the age-invariance of the
cut-off brightness over an extended interval, say from 1 to 13 Gyr, that
observations of PNLFs in galaxies of late-to-early type seem to suggest.


title: X-ray triple rings around the M87 jets in the central Virgo cluster

abstract:
  The Chandra X-ray data of the central Virgo cluster are re-examined to reveal
a triple-ring structure around the galaxy M87, reminiscent of the spectacular
triple-ring pattern of the SN1987A in the Large Magellanic Cloud (LMC). In the
sky plane, the two apparent smaller ellipses are roughly aligned along the M87
jets; the larger ring centers at the M87 nucleus and is likely a circle roughly
perpendicular to the M87 jet. Certain similarities of these two triple-ring
structures might hint at similar processes that operate in these two systems
with entirely different sizes and mass scales. We suspect that a major merging
event of two galaxies with nuclear supermassive black holes (SMBHs) might
create such a triple-ring structure and drove acoustic and internal gravity
waves far and near. The M87 jets are perhaps powered by a spinning SMBH
resulting from this catastrophic merging event.


title: WMAP constraints on low redshift evolution of dark energy

abstract:
  The conceptual difficulties associated with a cosmological constant have led
to the investigation of alternative models in which the equation of state
parameter, $w=p/\rho$, of the dark energy evolves with time. We show that
combining the supernova type Ia observations {\it with the constraints from
WMAP observations} restricts large variation of $\rho(z)$ at low redshifts. The
combination of these two observational constraints is stronger than either one.
The results are completely consistent with the cosmological constant as the
source of dark energy.


title:
Galactic Bulges from HST NICMOS Observations: central galaxian objects,
  and nuclear profile slopes

abstract:
  We have measured the central structural properties for a sample of S0-Sbc
galaxies down to scales of ~10 pc using HST NICMOS images. We find that the
photometric masses of the central star clusters, which occur in 58% of our
sample, are related to their host bulge masses such that MassPt =
10^{7.75\pm0.15}(MassBul/10^{10}MassSun)^{0.76\pm 0.13}. Put together with
recent data on bulges hosting supermassive black holes, we infer a non-linear
dependency of the `Central Massive Object' mass on the host bulge mass such
that MassCMO = 10^{7.51\pm 0.06} (MassBul/10^{10}MassSun)^{0.84 \pm 0.06}. We
argue that the linear relation presented by Ferrarese et al. is biased at the
low-mass end by the inclusion of the disc light from lenticular galaxies in
their sample. Matching our NICMOS data with wider-field, ground-based K-band
images enabled us to sample from the nucleus to the disk-dominated region of
each galaxy, and thus to perform a proper bulge-disk decomposition. We found
that the majority of our galaxies (~90%) possess central light excesses which
can be modeled with an inner exponential and/or an unresolved point source in
the case of the nuclear star clusters. All the extended nuclear components,
with sizes of a few hundred pc, have disky isophotes, which suggest that they
may be inner disks, rings, or bars; their colors are redder than those of the
underlying bulge, arguing against a recent origin for their stellar
populations. Surface brightness profiles rise inward to the resolution limit of
the data, with a continuous distribution of logarithmic slopes from the low
values typical of dwarf ellipticals (0.1 \leq gamma \leq 0.3) to the high
values (gamma ~ 1) typical of intermediate luminosity ellipticals; the nuclear
slope bi-modality reported by others is not present in our sample.


title: Effects of the Environment on the Properties of Seyfert Galaxies

abstract:
  We identify 175 Seyfert galaxies from the Southern Sky Redshift Survey -
SSRS2. We use the entire SSRS2 catalog to investigate the correlation between
the presence of AGN with host environment. The AGN phenomenon is more strongly
correlated with the internal host properties, than with the external
environment. In particular, we find that Seyferts reside in more luminous
galaxies, and are twice as frequent in barred galaxies and systems showing sign
of advanced merger condition, when compared to a control sample.


title: Galactic Bulges from HST NICMOS Observations: Global Scaling Relations

abstract:
  We investigate bulge and disk scaling relations using a volume-corrected
sample of early- to intermediate-type disk galaxies in which, importantly, the
biasing flux from additional nuclear components has been modeled and removed.
Structural parameters are obtained from a seeing-convolved,
bulge+disk+nuclear-component decomposition applied to near-infrared surface
brightness profiles spanning ~10 pc to the outer disk. Bulge and disk
parameters, and bulge-to-disk ratios, are analyzed as a function of bulge
luminosity, disk luminosity, galaxy central velocity dispersion, and galaxy
Hubble type. Mathematical expressions are given for the stronger relations,
which can be used to test and constrain galaxy formation models. Photometric
parameters of both bulges and disks are observed to correlate with bulge
luminosity and with central velocity dispersion. In contrast, for the unbarred,
early to intermediate types covered by the sample, Hubble type does not
correlate with bulge and disk components, nor their various ratios. In this
sense, the early-to-intermediate spiral Hubble sequence is scale-free. However,
galaxies themselves are not scale-free, the critical scale being the luminosity
of the bulge. Bulge luminosity is shown to affect the disk parameters, such
that central surface brightness becomes fainter, and scale-length bigger, with
bulge luminosity. The lack of significant correlations between bulge
pararmeters (size, luminosity or density) on disk luminosity, remains a
challenge for secular evolution models of bulge growth.


title: Constraints to cosmological parameters through clusters evolution

abstract:
  In this paper, I revisit the constraints obtained by several authors
(Reichart et al. 1999; Eke et al. 1998; Henry 2000) on the estimated values of
Omegam, n and sigma_8 in the light of recent theoretical developments: 1) new
theoretical mass functions (Sheth & Tormen 1999, Sheth, Mo & Tormen 2001, Del
Popolo 2002b); 2) a more accurate mass-temperature relation, also determined
for arbitrary Omega_m and Omega_Lambda (Del Popolo 2002a).


title:
Photoevaporation of Circumstellar Disks due to External FUV Radiation in
  Stellar Aggregates

abstract:
  When stars form in small groups (N = 100 - 500 members), their circumstellar
disks are exposed to little EUV radiation but a great deal of FUV radiation
from massive stars in the group. This paper calculates mass loss rates for
circumstellar disks exposed to external FUV radiation. Previous work treated
large disks and/or intense radiation fields in which the disk radius exceeds
the critical radius (supercritical disks) where the sound speed in the FUV
heated layer exceeds the escape speed. This paper shows that significant mass
loss still takes place for subcritical systems. Some of the gas extends beyond
the disk edge (above the disk surface) to larger distances where the
temperature is higher, the escape speed is lower, and an outflow develops. The
evaporation rate is a sensitive function of the stellar mass and disk radius,
which determine the escape speed, and the external FUV flux, which determines
the temperature structure of the flow. Disks around red dwarfs are readily
evaporated and shrink to disk radii of 15 AU on short time scales (10 Myr) when
exposed to moderate FUV fields with $G_0$ = 3000. Although disks around solar
type stars are more durable, these disks shrink to 15 AU in 10 Myr for intense
FUV radiation fields with $G_0$ = 30,000; such fields exist in the central 0.7
pc of a cluster with N = 4000 stars. If our solar system formed in the presence
of such strong FUV radiation fields, this mechanism could explain why Neptune
and Uranus in our solar system are gas poor, whereas Jupiter and Saturn are gas
rich. This mechanism for photoevaporation can also limit the production of
Kuiper belt objects and can suppress giant planet formation in sufficiently
large clusters, such as the Hyades, especially for disks associated with low
mass stars.


title:
Improvement of the CORS method for Cepheids radii determination based on
  Stromgren photometry

abstract:
  In this paper we present a modified version of the CORS method based on a new
calibration of the Surface Brightness function in the Stromgren photometric
system. The method has been tested by means of synthetic light and radial
velocity curves derived from nonlinear pulsation models. Detailed simulations
have been performed to take into account the quality of real observed curves as
well as possible shifts between photometric and radial velocity data. The
method has been then applied to a sample of Galactic Cepheids with Stromgren
photometry and radial velocity data to derive the radii and a new PR relation.
As a result we find log R = (1.19 +- 0.09) + (0.74 +- 0.11) log P (r.m.s=0.07).
The comparison between our result and previous estimates in the literature is
satisfactory. Better results are expected from the adoption of improved model
atmosphere grids.


title: XMM-Newton EPIC observations of 21 low-redshift PG quasars

abstract:
  We present an X-ray spectral analysis of 21 low redshift quasars observed
with XMM-Newton EPIC. All the sources are Palomar Green quasars with redshifts
between 0.05 and 0.4 and have low Galactic absorption along the line-of-sight.
A large majority of quasars in the sample (19/21) exhibit a significant soft
excess below ~1-1.5keV, whilst two objects (PG1114+445 and IZw1) show a deficit
of soft X-ray flux due to the presence of a strong warm absorber. At least half
of the objects appear to harbor a warm absorber, as found previously in Seyfert
1 galaxies. We find significant detections of FeKalpha emission lines in at
least twelve objects, whilst there is evidence for some broadening of the line
profile, compared to the EPIC-pn resolution, in five of these quasars.
  The determination of the nature of this broadening (e.g., Keplerian motion, a
blend of lines, relativistic effects) is not possible with the present data and
requires either higher S/N or higher resolution spectra. In seven objects the
line is located between 6.7-7keV, corresponding to highly ionized iron, whereas
in the other five objects the line energy is consistent with 6.4 keV, i.e.
corresponding to near neutral iron. The ionized lines tend to be found in the
quasars with the steepest X-ray spectra. We also find a correlation between the
continuum power law index and the optical Hbeta width, in both the soft and
hard X-ray bands, whereby the steepest X-ray spectra are found in objects with
narrow Hbeta widths, which confirms previous ROSAT and ASCA results. The soft
and hard band X-ray photon indices are also strongly correlated, i.e. the
steepest soft X-ray spectra correspond the steepest hard X-ray spectra.


title:
Streaming motions of galaxy clusters within 12000 km/s - V. The peculiar
  velocity field

abstract:
  We analyze in detail the peculiar velocity field traced by 56 clusters within
120 h^-1 Mpc in the Streaming Motions of Abell Clusters (SMAC) sample. The bulk
flow of the SMAC sample is 687 +- 203 km/s, toward l = 260 +- 13, b = 0 +- 11.
We discuss possible systematic errors and show that no systematic effect is
larger than half of the random error. The flow does not drop off significantly
with depth, which suggests that it is generated by structures on large scales.
In particular, a Great Attractor as originally proposed by Lynden-Bell et al.
cannot be responsible for the SMAC bulk flow. The SMAC data suggest infall into
an attractor at the location of the Shapley Concentration, but the detection is
marginal (at the 90% confidence level). We find that distant attractors in
addition to the Shapley Concentration are required to explain the SMAC bulk
flow. A comparison with peculiar velocities predicted from the IRAS PSCz
redshift survey shows good agreement with a best fit value of Beta_I =
Omega^0.6/b_I = 0.39 +- 0.17. However, the PSCz density field is not sufficient
to acount for all of the SMAC bulk motion. We also detect, at the 98%
confidence level, a residual bulk flow of 372 +- 127 km/s toward l = 273, b = 6
which must be generated by sources not included in the PSCz catalogue, that is,
either beyond 200 h^-1 Mpc, in the Zone of Avoidance or in superclusters
undersampled by IRAS. Finally, we compare the SMAC bulk flow with other recent
measurements. We suggest that a bulk flow of 225 km/s toward l = 300, b = 10 at
depths greater than 60 h^-1 Mpc is consistent with all peculiar velocity
surveys, when allowance is made for sparse sampling effects. (abridged)


title: Neutrino Bursts from Fanaroff-Riley I Radio Galaxies

abstract:
  On the basis of existing observations (at the 4.5 \sigma level) of TeV
gamma-ray outbursts from the Fanaroff-Riley I (FRI) radio galaxy Centaurus A,
we estimate the accompanying neutrino flux in a scenario where both photons and
neutrinos emerge from pion decay. We find a neutrino flux on Earth
dF_{\nu}/dE_\nu = 4.5\times 10^{-11} (E_\nu/TeV)^{-2} TeV^{-1} cm^{-2} s^{-1},
equally spread in flavor as a result of maximal mixing. Such a flux will
trigger at the IceCube facility about 10 showers/burst, with negligible
background from atmospheric muons, and primary neutrino energies in excess of
100 TeV. The only other FRI radio galaxy observed in the TeV photon energy
range at the 4\sigma level is M87. The burst nature of this activity is not
established; however, we show that the intrinsic neutrino luminosity during the
active period is the same as the Centaurus A burst. On the assumption that
Centaurus A typifies the FRI population, we show that IceCube should collect 10
showers (all neutrino flavors) in 3 years, attaining a 95% CL sensitivity to
the diffuse neutrino flux from FRI radio galaxies in one year of observation.


title:
Optimal Asymmetric Apodizations and Shaped Pupils for Planet Finding
  Coronagraphy

abstract:
  The realization that direct imaging of extrasolar planets could be
technologically feasible within the next decade or so has inspired a great deal
of recent research into high-contrast imaging. We ourselves have contributed
several design ideas, all of which can be described as shaped pupil
coronagraphs. In this paper, we offer a complete and unified survey of
asymmetric shaped pupils designs, some of which have been published in our
previous papers. We also introduce a promising new design, which we call
barcode masks. These masks achieve the required contrast with a fairly large
discovery zone and throughput but most importantly they are perhaps the easiest
to manufacture and might therefore stand up best to a refined analysis based on
vector propogation techniques.


title:
Gravitational Waves from Supermassive Black Hole Coalescence in a
  Hierarchical Galaxy Formation Model

abstract:
  We investigate the expected gravitational wave emission from coalescing
supermassive black hole (SMBH) binaries resulting from mergers of their host
galaxies. When galaxies merge, the SMBHs in the host galaxies sink to the
center of the new merged galaxy and form a binary system. We employ a
semi-analytic model of galaxy and quasar formation based on the hierarchical
clustering scenario to estimate the amplitude of the expected stochastic
gravitational wave background owing to inspiraling SMBH binaries and bursts
owing to the SMBH binary coalescence events. We find that the characteristic
strain amplitude of the background radiation is $h_c(f) \sim 10^{-16} (f/1 \mu
{\rm Hz})^{-2/3}$ for $f \lesssim 1 \mu {\rm Hz}$ just below the detection
limit from measurements of the pulsar timing provided that SMBHs coalesce
simultaneously when host galaxies merge. The main contribution to the total
strain amplitude of the background radiation comes from SMBH coalescence events
at $0<z<1$. We also find that a future space-based gravitational wave
interferometer such as the planned \textit{Laser Interferometer Space Antenna}
({\sl LISA}) might detect intense gravitational wave bursts associated with
coalescence of SMBH binaries with total mass $M_{\rm tot} < 10^7 M_{\odot}$ at
$z \gtrsim 2$ at a rate $ \sim 1.0 {\rm yr}^{-1}$. Our model predicts that
burst signals with a larger amplitude $h_{\rm burst} \sim 10^{-15}$ correspond
to coalescence events of massive SMBH binary with total mass $M_{\rm tot} \sim
10^8 M_{\odot}$ at low redshift $ z \lesssim 1$ at a rate $ \sim 0.1 {\rm
yr}^{-1}$ whereas those with a smaller amplitude $h_{\rm burst} \sim 10^{-17}$
correspond to coalescence events of less massive SMBH binary with total mass
$M_{\rm tot} \sim 10^6 M_{\odot}$ at high redshift $ z \gtrsim 3$.


title: Neutralino Relic Density Enhancement in Non-Standard Cosmologies

abstract:
  The thermal relic abundance of species critically depends on the assumed
underlying cosmological model. In the case of neutralinos, freeze-out takes
place long before Big Bang Nucleosynthesis, which provides the strongest
constraint on the evolution of the Hubble parameter in the Early Universe. We
show that non-standard cosmologies, such as models featuring a quintessential
scalar field or primordial anisotropies, can lead to large enhancements in the
neutralino relic abundance, up to six orders of magnitudes. Within these
scenarios, supersymmetric models with large neutralino annihilation cross
sections may account for the whole inferred amount of cold dark matter,
yielding on the other hand large indirect detection rates.


title:
Measurements of Sunyaev-Zel'dovich Effect Scaling Relations for Clusters
  of Galaxies

abstract:
  We present new measurements of the Sunyaev-Zel'dovich (SZ) effect from
clusters of galaxies using the Sunyaev-Zel'dovich Infrared Experiment (SuZIE
II). We combine these new measurements with previous cluster observations with
the SuZIE instrument to form a sample of 15 clusters of galaxies. For this
sample we calculate the central Comptonization, y, and the integrated SZ flux
decrement, S, for each of our clusters. We find that the integrated SZ flux is
a more robust observable derived from our measurements than the central
Comptonization due to inadequacies in the spatial modelling of the
intra-cluster gas with a standard Beta model. This is highlighted by comparing
our central Comptonization results with values calculated from measurements
using the BIMA and OVRO interferometers. On average, the SuZIE calculated
central Comptonizations are approximately 60% higher in the cooling flow
clusters than the interferometric values, compared to only approximately 12%
higher in the non-cooling flow clusters. We believe this discrepancy to be in
large part due to the spatial modelling of the intra-cluster gas. From our
cluster sample we construct y-T and S-T scaling relations. The y-T scaling
relation is inconsistent with what we would expect for self-similar clusters;
however this result is questionable because of the large systematic uncertainty
in the central Comptonization. The S-T scaling relation has a slope and
redshift evolution consistent with what we expect for self-similar clusters
with a characteristic density that scales with the mean density of the
universe. We rule out zero redshift evolution of the S-T relation at 90%
confidence.


title:
Fluctuation and morphological properties of the pulsars in J0737--3039
  system

abstract:
  We describe the morphological and fluctuation properties of the pulsars in
the double neutron star system, PSR J0737--3039. Pulsar B is seen in almost all
orbital phases, except in the range of $\sim 6\deg$ to $65\deg$. This may be
interpreted as an {\it eclipse} of pulsar B's signal by its own magnetopause
region produced by interaction with pulsar A's relativistic wind. No modulation
of the emission of pulsar B is found at the period of pulsar A. This places a
constraint on the models that propose that pulsar A's beamed radiation is
directly responsible for pulsar B's emission. Modulation index values indicate
that the pulse to pulse variations in the two objects are mostly intrinsic.
Pulsar A shows significant differential modulation index within its pulse
profile.


title: Spectroscopic Observations and Analysis of the Peculiar SN 1999aa

abstract:
  We present an extensive new time-series of spectroscopic data of the peculiar
SN 1999aa in NGC 2595. Our data set includes 25 optical spectra between -11 and
+58 days with respect to B-band maximum light, providing an unusually complete
time history. The early spectra resemble those of a SN 1991T-like object but
with a relatively strong Ca H&K absorption feature. The first clear sign of Si
II 6355, characteristic of Type Ia supernovae, is found at day -7 and its
velocity remains constant up to at least the first month after B-band maximum
light. The transition to normal-looking spectra is found to occur earlier than
in SN 1991T suggesting SN 1999aa as a possible link between SN 1991T-like and
Branch-normal supernovae. Comparing the observations with synthetic spectra,
doubly ionized Fe, Si and Ni are identified at early epochs. These are
characteristic of SN 1991T-like objects. Furthermore, in the day -11 spectrum,
evidence is found for an absorption feature which could be identified as high
velocity C II 6580 or H-alpha. At the same epoch C III 4648.8 at photospheric
velocity is probably responsible for the absorption feature at 4500 A. High
velocity Ca is found around maximum light together with Si II and Fe II
confined in a narrow velocity window. Implied constraints on supernovae
progenitor systems and explosion hydrodynamical models are briefly discussed.


title: OGLE-2003-BLG-238: Microlensing Mass Estimate of an Isolated Star

abstract:
  Microlensing is the only known direct method to measure the masses of stars
that lack visible companions. In terms of microlensing observables, the mass is
given by M=(c^2/4G)\tilde r_E \theta_E and so requires the measurement of both
the angular Einstein radius, \theta_E, and the projected Einstein radius,
\tilde r_E. Simultaneous measurement of these two parameters is extremely rare.
Here we analyze OGLE-2003-BLG-238, a spectacularly bright (I_min=10.3),
high-magnification (A_max = 170) microlensing event. Pronounced finite source
effects permit a measurement of \theta_E = 650 uas. Although the timescale of
the event is only t_E = 38 days, one can still obtain weak constraints on the
microlens parallax: 4.4 AU < \tilde r_E < 18 AU at the 1 \sigma level. Together
these two parameter measurements yield a range for the lens mass of 0.36 M_sun
< M < 1.48 M_sun. As was the case for MACHO-LMC-5, the only other single star
(apart from the Sun) whose mass has been determined from its gravitational
effects, this estimate is rather crude. It does, however, demonstrate the
viability of the technique. We also discuss future prospects for single-lens
mass measurements.


title: Luminosity Profiles of Resolved Young Massive Clusters

abstract:
  Young massive clusters (YMCs) differ markedly from old globular clusters in
featuring extended, rather than tidally truncated, envelopes. Their projected-
luminosity profiles are well fit by Elson-Fall-Freeman (EFF) models with core
radii of 0.3 pc < r_c < 8 pc and power-law envelopes of negative exponent 2 <
gamma < 3.8. These envelopes form within the first few 10^6 yr and last ~10^8
to 10^9.5 yr, depending on the environment. Many young massive clusters show
clumpy substructure that may accelerate their initial relaxation. The cores of
Magellanic-Cloud clusters show universal expansion from r_c < 1 pc at birth to
r_c = 2 - 3 pc after 10^8 yr, but then seem to evolve along two bifurcating
branches in a r_c-log(age) diagram. The lower branch can be explained by
mass-loss driven core expansion during the first 10^9 yr, followed by slow core
contraction and the onset of core collapse due to evaporation. The upper
branch, which shows continued core expansion proportional to logarithmic age,
remains unexplained. There is strong evidence for rapid mass segregation in
young clusters, yet little evidence for top-heavy IMFs or primordial mass
segregation. Finally, YMCs show similar structure throughout the Local Group
and as far away as we can resolve them (<~20 Mpc).


title:
Excitation and Propagation of Eccentricity Disturbances in Planetary
  Systems

abstract:
  The high eccentricities of the known extrasolar planets remain largely
unexplained. We explore the possibility that eccentricities are excited in the
outer parts of an extended planetary disk by encounters with stars passing at a
few hundreds of AU. After the encounter, eccentricity disturbances propagate
inward due to secular interactions in the disks, eventually exciting the
innermost planets. We study how the inward propagation of eccentricity in
planetary disks depends on the number and masses of the planets and spacing
between them and on the overall surface-density distribution in the disk. The
main governing factors are the large-scale surface-density distribution and the
total size of the system. If the smeared-out surface density is approximated by
a power-law \Sigma(r)\propto r^{-q}, then eccentricity disturbances propagate
inward efficiently for flat density distributions with q < 1. If this condition
is satisfied and the size of the planetary system is 50 AU or larger, the
typical eccentricities excited by this mechanism by field star encounters in
the solar neighborhood over 5 Gyr are in the range 0.01-0.1. Higher
eccentricities (> 0.1) may be excited in planetary systems around stars that
are formed in relatively dense, long-lived open clusters. Therefore, this
mechanism may provide a natural way to excite the eccentricities of extrasolar
planets.


title: A Hierarchy of Voids

abstract:
  We present a model for the distribution of void sizes and its evolution
within the context of hierarchical scenarios of gravitational structure
formation. For a proper description of the hierarchical buildup of the system
of voids in the matter distribution, not only the "void-in-void" problem should
be taken into account, but also that of the "void-in-cloud" issue. Within the
context of the excursion set formulation of an evolving void hierarchy is one
involving a "two-barrier" excursion problem, unlike the "one-barrier" problem
for the dark halo evolution. This leads to voids having a peaked size
distribution at any cosmic epoch, centered on a characteristic void size that
evolves self-similarly in time, this in distinct contrast to the distribution
of virialized halo masses which do not have a small-scale cut-off.


title:
Magellanic Cloud Cepheids: Pulsational and Evolutionary Modelling vs.
  Observations

abstract:
  The pulsational properties of the Cepheid models along the evolutionary
tracks from the Padova group (Girardi et al.), as calculated with our turbulent
convective pulsation code, are in good agreement with the resonance constraints
imposed by the observational OGLE-2 data of the Small and Large Magellanic
Clouds. Our study suggests that the P_4/P_1=1/2 resonance for the overtone
Cepheids occurs for periods clustering around 4.2 d, in disagreement with the
suggestion of Antonello & Poretti based on the observations of light curves,
but in agreement with Kienzle et al. and Feuchtinger et al. For the fundamental
Cepheids the lowest order Fourier decomposition coefficients from the light
curves, \viz R_21 and phi_21 can be used to locate the resonance region, but
not so for the first overtone Cepheids. Here, the radial velocity curves can be
used to locate the overtone resonance region, or in their absence, one needs to
resort to numerical hydrodynamic modelling.


title: Physical Conditions in Orion's Veil

abstract:
  Orion's veil consists of several layers of largely neutral gas lying between
us and the main ionizing stars of the Orion nebula. It is visible in 21cm H I
absorption and in optical and UV absorption lines of H I and other species.
Toward the Trapezium, the veil has two remarkable properties, high magnetic
field (~100 microGauss) and a surprising lack of molecular hydrogen given its
total hydrogen column density. Here we compute photoionization models of the
veil to establish its gas density and its distance from the Trapezium. We use a
greatly improved model of the hydrogen molecule that determines level
populations in ~1e5 rotational/vibrational levels and provides improved
estimates of molecular hydrogen destruction via the Lyman-Werner bands. Our
best fit photoionization models place the veil 1-3 pc in front of the star at a
density of 1e3-1e4 cubic centimeters. Magnetic energy dominates the energy of
non-thermal motions in at least one of the 21cm H I velocity components.
Therefore, the veil is the first interstellar environment where magnetic
dominance appears to exist. We find that the low ratio of molecular to atomic
hydrogen (< 1e-4) is a consequence of high UV flux incident upon the veil due
to its proximity to the Trapezium stars and the absence of small grains in the
region.


title:
Constraints On The Topology Of The Universe From The WMAP First-Year Sky
  Maps

abstract:
  We compute the covariance expected between the spherical harmonic
coefficients $a_{\ell m}$ of the cosmic microwave temperature anisotropy if the
universe had a compact topology. For fundamental cell size smaller than the
distance to the decoupling surface, off-diagonal components carry more
information than the diagonal components (the power spectrum). We use a maximum
likelihood analysis to compare the Wilkinson Microwave Anisotropy Probe
first-year data to models with a cubic topology. The data are compatible with
finite flat topologies with fundamental domain $L > 1.2$ times the distance to
the decoupling surface at 95% confidence. The WMAP data show reduced power at
the quadrupole and octopole, but do not show the correlations expected for a
compact topology and are indistinguishable from infinite models.


title: An Approach to Neutrino Radiative Transfer in Supernova Simulations

abstract:
  Neutrinos dominate the energetics of core-collapse supernovae, and are
believed to play an important role in driving the explosion. The development of
a spatially multidimensional neutrino radiative transfer code is a key part of
the Terascale Supernova Initiative, a multi-year effort aimed at understanding
the supernova explosion mechanism through supercomputer simulations. I will
describe the conservative formulations of general relativistic radiative
transfer we have developed for this application, and the algorithm we are
implementing in our parallel code.


title:
Cosmic acceleration and extra dimensions: constraints on modifications
  of the Friedmann equation

abstract:
  An alternative to dark energy as an explanation for the present phase of
accelerated expansion of the Universe is that the Friedmann equation is
modified, e.g. by extra dimensional gravity, on large scales. We explore a
natural parametrization of a general modified Friedmann equation, and find that
the present supernova type Ia and cosmic microwave background data prefer a
correction of the form 1/H over a cosmological constant. We also explore the
constraints that can be expected in the future, and find that there are good
prospects for distinguishing this model from the standard cosmological constant
to very high significance if one combines supernova data with a precise
measurement of the matter density.


title:
The Red Giant Branch in Near-Infrared Colour-Magnitude Diagrams. II: The
  luminosity of the Bump and the Tip

abstract:
  We present new empirical calibrations of the Red Giant Branch (RGB) Bump and
Tip based on a homogeneous near-Infrared database of 24 Galactic Globular
Clusters. The luminosities of the RGB Bump and Tip in the J, H and K bands and
their dependence on the cluster metallicity have been studied, yielding
empirical relationships. By using recent transformations between the
observational and theoretical planes, we also derived similar calibrations in
terms of bolometric luminosity. Direct comparison between updated theoretical
models and observations show an excellent agreement. The empirical calibration
of the RGB Tip luminosity in the near-Infrared passbands presented here is a
fundamental tool to derive distances to far galaxies beyond the Local Group, in
view of using the new ground-based adaptive optics facilities and, in the next
future, the James Webb Space Telescope.


title:
On the Measurement of Elemental Abundance Ratios in Inner Galaxy H II
  Regions

abstract:
  Although variations in elemental abundance ratios in the Milky Way Galaxy
certainly exist, details remain uncertain, particularly in the inner Galaxy,
where stars and H II regions in the Galactic plane are obscured optically. In
this paper we revisit two previously studied, inner Galaxy H II regions:
G333.6-0.2 and W43. We observed three new positions in G333.6-0.2 with the
Kuiper Airborne Observatory and reobserved the central position with the
Infrared Space Observatory's Long Wavelength Spectrometer in far-infrared lines
of S++, N++, N+, and O++. We also added the N+ lines at 122 and 205 micron to
the suite of lines measured in W43 by Simpson et al. (1995). The measured
electron densities range from ~40 to over 4000 cm-3 in a single H II region,
indicating that abundance analyses must consider density variations, since the
critical densities of the observed lines range from 40 to 9000 cm-3. We propose
a method to handle density variations and make new estimates of the S/H and N/H
abundance ratios. We find that our sulfur abundance estimates for G333.6-0.2
and W43 agree with the S/H abundance ratios expected for the S/H abundance
gradient previously reported by Simpson et al. The estimated N/H, S/H, and N/S
ratios are the most reliable because of their small corrections for unseen
ionization states (< 10%). We compute models of the two H II regions to
estimate corrections for the other unseen ionization states. We discuss these
predictions and conclude that only a few of the latest models adequately
reproduce H II region observations, including the well-known, relatively-large
observed Ne++/O++ ratios in low- and moderate-excitation H II regions.


title:
Warm gas in the outskirts of galaxy clusters -- The cluster soft excess
  phenomenon

abstract:
  The cluster soft excess emission indicates the presence of large amounts of
warm gas (T ~ 10^6 K) in the neighborhood of galaxy clusters. Among the
clusters that display this phenomenon is the Coma cluster, the nearest rich
galaxy cluster. The excess emission is more prominent at the cluster's
outskirts than at its center. Detailed studies of its large-scale emission --
up to ~2.6 Mpc from the cluster's center -- reveal that these warm baryons are
as massive as, or possibly more massive than, the well-known hot intra-cluster
medium (T ~10^8 K). A possible interpretation of the excess emission from the
Coma cluster is radiation from low-density filaments located in the
neighborhood of the cluster. In this case, the filaments would extend for much
larger distances, or feature higher density, than predicted by current
cosmological simulations.


title: Masers and Outflows in the W3(OH)/W3(H2O) region

abstract:
  Methanol masers and molecular shock tracers were observed in the
W3(OH)/W3(H$_2$O) region with the BIMA array and the Onsala 20m radiotelescope.
Characteristics of the outflows in the region are discussed. A model of the
W3(OH) methanol maser formation region is constructed.


title:
Stellar Dynamics at the Galactic Center with an Extremely Large
  Telescope

abstract:
  We discuss experiments achievable via monitoring of stellar dynamics near the
massive black hole at the Galactic center with a next generation, extremely
large telescope (ELT). Given the likely observational capabilities of an ELT
and current knowledge of the stellar environment at the Galactic center, we
synthesize plausible samples of stellar orbits around the black hole. We use
the Markov Chain Monte Carlo method to evaluate the constraints that orbital
monitoring places on the matter content near the black hole. Results are
expressed as functions of the number N of stars with detectable orbital motions
and the astrometric precision dtheta and spectroscopic precision dv at which
stellar proper motions and radial velocities are monitored. For N = 100, dtheta
= 0.5 mas, and dv = 10 km/s -- a conservative estimate of the capabilities of a
30 meter telescope -- the extended matter distribution enclosed by the orbits
will produce measurable deviations from Keplerian motion if >1000 Msun is
enclosed within 0.01 pc. The black hole mass and distance to the Galactic
center will be measured to better than ~0.1%. Lowest-order relativistic
effects, such as the prograde precession, will be detectable if dtheta < 0.5
mas. Higher-order effects, including frame dragging due to black hole spin,
requires dtheta < 0.05 mas, or the favorable discovery of a compact, highly
eccentric orbit. Finally, we calculate the rate at which monitored stars
undergo detectable nearby encounters with background stars. Such encounters
probe the mass function of stellar remnants that accumulate near the black
hole. We find that ~30 encounters will be detected over a 10 yr baseline for
dtheta = 0.5 mas.


title: On the Chaotic Orbits of Disc-Star-Planet Systems

abstract:
  Following Tancredi, Sanchez and Roig (2001)'s criteria of chaos, two ways of
setting initial velocities are used in the numerical surveys to explore the
possible chaotic and regular orbits for the disc-star-planet systems. We find
that the chaotic boundary does not depend much on the disc mass for Type I
initial condition, but can change a lot for different disc masses for Type II
initial condition. A few sample orbits are further studied. Both Poincare
surface of section and the Lyapounov Exponent Indicator are calculated and they
are consistent with each other. We also find that the influence from the disc
can change the locations of equilibrium points and the orbital behaviors for
both types of initial conditions. Because the chaotic orbits are less likely to
become the stable resonant orbits, we conclude that the proto-stellar disc
shall play important roles for the capture and depletion histories of resonant
orbits of both Asteroid Belt and Kuiper Belt during the formation of Solar
System.


title: Ionization Mechanisms in Jet-Dominated Seyferts: A Detailed Case Study

abstract:
  For the past 10 years there has been an active debate over whether fast
shocks play an important role in ionizing emission line regions in Seyfert
galaxies. To investigate this claim, we have studied the Seyfert 2 galaxy Mkn
78, using HST UV/optical images and spectroscopy. Since Mkn 78 provides the
archetypal jet-driven bipolar velocity field, if shocks are important anywhere
they should be important in this object. Having mapped the emission line fluxes
and velocity field, we first compare the ionization conditions to standard
photoionization and shock models. We find coherent variations of ionization
consistent with photoionization model sequences which combine optically thick
and thin gas, but are inconsistent with either autoionizing shock models or
photoionization models of just optically thick gas. Furthermore, we find
absolutely no link between the ionization of the gas and its kinematic state,
while we do find a simple decline of ionization degree with radius. We feel
this object provides the strongest case to date against the importance of shock
related ionization in Seyferts.


title: The Intra-Cluster Medium

abstract:
  The Intra-Cluster Medium (ICM) is a rarefied, hot, highly ionized, metal
rich, weakly magnetized plasma. In these proceeding, after having reviewed some
basic ICM properties, I discuss recent results obtained with the BeppoSAX,
XMM-Newton and Chandra satellites. These results are summarized in the
following five points. 1) Currently available hard X-ray data does not allow us
to constrain B fields in radio halos, the advent of hard X-ray telescopes in a
few years may change the situation substantially. 2) There is mounting evidence
that temperature profiles of clusters at large radii decline; however
investigation of the outermost regions will have to await a new generation of
yet unplanned but technologically feasible experiments. 3) The ICM is polluted
with metals, the enrichment has probably occurred early on in the cluster's
life. The abundance excess observed at the center of CC clusters is due to the
giant elliptical always found in these systems. 4) Chandra and XMM-Newton
observations of relaxed clusters have falsified the previously accepted cooling
flow model, heating mechanisms that may offset the cooling are actively being
sought. 5) The superb angular resolution of Chandra is allowing us to trace a
previously unknown phenomenon intimately related to the formation of galaxy
clusters and of their cores.


title:
Statistical Significance of Small Scale Anisotropy in Arrival Directions
  of Ultra-High Energy Cosmic Rays

abstract:
  Recently, the High Resolution Fly's Eye (HiRes) experiment claims that there
is no small scale anisotropy in the arrival distribution of ultra-high energy
cosmic rays (UHECRs) above $E>10^{19}$ eV contrary to the Akeno Giant Air
Shower Array (AGASA) observation. In this paper, we discuss the statistical
significance of this discrepancy between the two experiments. We calculate
arrival distribution of UHECRs above $10^{19}$ eV predicted by the source
models constructed using the Optical Redshift Survey galaxy sample. We apply
the new method developed by us for calculating arrival distribution in the
presence of the galactic magnetic field. The great advantage of this method is
that it enables us to calculate UHECR arrival distribution with lower energy
($\sim 10^{19}$ eV) than previous studies within reasonable time by following
only the trajectories of UHECRs actually reaching the earth. It has been
realized that the small scale anisotropy observed by the AGASA can be explained
with the source number density $\sim 10^{-5 \sim -6}$ Mpc$^{-3}$ assuming weak
extragalactic magnetic field ($B \le 1$ nG). We find that the predicted small
scale anisotropy for this source number density is also consistent with the
current HiRes data. We thus conclude that the statement by the HiRes experiment
that they do not find small scale anisotropy in UHECR arrival distribution is
not statistically significant at present. We also show future prospect of
determining the source number density with increasing amount of observed data.


title: Methanol in W3(H2O) and Surrounding Regions

abstract:
  We present the results of an interferometric study of 38 millimeter-wave
lines of CH3OH in the region around the water maser source W3(H2O) and a region
extending about 30" to the south and west of the hydroxyl maser source W3(OH).
  The methanol emitting region around W3(H2O) has an extent of 2.0" x 1.2"
(4400 x 2600 AU). The density is of order 1.e7 cm-3, sufficient to thermalize
most of the methanol lines. The kinetic temperature is approximately 140 K and
the methanol fractional abundance greater than 1.e-6, indicative of a high
degree of grain mantle evaporation. The W3(H2O) source contains sub-structure,
with peaks corresponding to the TW source and Wyrowski's B/C, separated by 2500
AU in projection. The kinematics are consistent with these being distinct
protostellar cores in a wide binary orbit and a dynamical mass for the region
of a few tens of Mo.
  The extended methanol emission to the southwest of W3(OH) is seen strongly
only from the lowest excitation lines and from lines known elsewhere to be
class I methanol masers, namely the 84.5 GHz 5(-1)-4(0)E and 95.2 GHz
8(0)-7(1)A+ lines. Within this region there are two compact clumps, which we
denote as swA and swB, each about 15" (0.16 pc projected distance) away from
W3(OH). Excitation analysis of these clumps indicates the presence of lines
with inverted populations but only weak amplification. The sources swA and swB
appear to have kinetic temperatures of order 50-100 K and densities of order
1.e5 - 1.e6 cm-3. The methanol fractional abundance for the warmer clump is of
order 1.e-7, suggestive of partial grain mantle evaporation. The clumping
occurs on mass scales of order 1 Mo.


title: The Clustering of XMM-Newton Hard X-ray Sources

abstract:
  This paper presents the clustering properties of hard (2-8 keV) X-ray
selected sources detected in a wide field ($\approx \rm 2 deg^{2}$) shallow
[$f_X(\rm 2-8 keV)\approx 10^{-14}\rm erg cm^{-2} s^{-1}$] and contiguous
XMM-{\it Newton} survey. We perform an angular correlation function analysis
using a total of 171 sources to the above flux limit. We detect a $\sim
4\sigma$ correlation signal out to 300 arcsec with $w(\theta < 300^{''})\simeq
0.13 \pm 0.03$. Modeling the two point correlation function as a power law of
the form $w(\theta)=(\theta_{\circ}/\theta)^{\gamma-1}$ we find:
$\theta_{\circ}=48.9^{+15.8}_{-24.5}$ arcsec and $\gamma=2.2\pm {0.30}$. Fixing
the correlation function slope to $\gamma=1.8$ we obtain
$\theta_{\circ}=22.2^{+9.4}_{-8.6}$ arcsec. Using Limber's intergral equation
and a variety of possible luminosity functions of the hard X-ray population, we
find a relatively large correlation length, ranging from $r_{\circ}\sim 9$ to
19 $h^{-1}$ Mpc (for $\gamma=1.8$ and the {\em concordance} cosmological
model), with this range reflecting also different evolutionary models for the
source luminosities and clustering characteristics. The relatively large
correlation length is comparable to that of extremely red objects and luminous
radio sources.


title:
Structure and kinematics of edge-on galaxy discs - I. Observations of
  the stellar kinematics

abstract:
  We present deep optical long-slit spectra of 17 edge-on spiral galaxies of
intermediate to late morphological type, mostly parallel to their major axes
and in a few cases parallel to the minor axes.The line-of-sight stellar
kinematics are obtained from the stellar absorption lines using the improvedc
ross-correlation technique. In general, the stellar kinematics are regular and
can be traced well into the disc-dominated region. The mean stellar velocity
curves are far from solid-body, indicating that the effect of dust extinction
is not large. The line-of-sight stellar disc velocity dispersion correlates
with the galaxy maximum rotational velocity, but detailed modeling is necessary
to establish whether this represents a physical relation. In four spirals with
a boxy- or peanut-shaped bulge we are able to detect asymmetric velocity
distributions, having a common signature with projected radius in the mean
line-of-sight velocity and the $h_{3}$ and $h_{4}$ curves. In two cases this
kinematic asymmetry probably represents the `figure-of-eight' pattern
synonymous of a barred potential. We emphasize, however, that the signatures
seen in the $h_{3}$ and $h_{4}$ curves may also be due to the disc seen in
projection.


title: Breaking the mass / anisotropy degeneracy in the Coma cluster

abstract:
  We provide the first direct lifting of the mass/anisotropy degeneracy for a
cluster of galaxies, by jointly fitting the line of sight velocity dispersion
and kurtosis profiles of the Coma cluster, assuming an NFW tracer density
profile, a generalized-NFW dark matter profile and a constant anisotropy
profile. We find that the orbits in Coma must be quasi-isotropic, and find a
mass consistent with previous analyses, but a concentration parameter 50%
higher than expected in cosmological N-body simulations. We then test the
accuracy of our method on realistic non-spherical systems with substructure and
streaming motions, by applying it to the ten most massive structures in a
cosmological N-body simulation. We find that our method yields fairly accurate
results on average (within 20%), although with a wide variation (factor 1.7 at
1 sigma) for the concentration parameter, with decreased accuracy and
efficiency when the projected mean velocity is not constant with radius.


title:
The Deep Lens Survey Transient Search I : Short Timescale and
  Astrometric Variability

abstract:
  We report on the methodology and first results from the Deep Lens Survey
transient search. We utilize image subtraction on survey data to yield all
sources of optical variability down to 24th magnitude. Images are analyzed
immediately after acquisition, at the telescope and in near-real time, to allow
for followup in the case of time-critical events. All classes of transients are
posted to the web upon detection. Our observing strategy allows sensitivity to
variability over several decades in timescale. The DLS is the first survey to
classify and report all types of photometric and astrometric variability
detected, including solar system objects, variable stars, supernovae, and short
timescale phenomena. Three unusual optical transient events were detected,
flaring on thousand-second timescales. All three events were seen in the B
passband, suggesting blue color indices for the phenomena. One event (OT
20020115) is determined to be from a flaring Galactic dwarf star of spectral
type dM4. From the remaining two events, we find an overall rate of \eta = 1.4
events deg-2 day-1 on thousand-second timescales, with a 95% confidence limit
of \eta < 4.3. One of these events (OT 20010326) originated from a compact
precursor in the field of galaxy cluster Abell 1836, and its nature is
uncertain. For the second (OT 20030305) we find strong evidence for an extended
extragalactic host. A dearth of such events in the R passband yields an upper
95% confidence limit on short timescale astronomical variability between 19.5 <
R < 23.4 of \eta_R < 5.2. We report also on our ensemble of astrometrically
variable objects, as well as an example of photometric variability with an
undetected precursor.


title:
Stellar evolution with rotation and magnetic fields II: General
  equations for the transport by Tayler--Spruit dynamo

abstract:
  We further develop the Tayler--Spruit dynamo theory, based on the most
efficient instability for generating magnetic fields in radiative layers of
differentially rotating stars. We avoid the simplifying assumptions that either
the $\mu$-- or the $T$--gradient dominates, but we treat the general case and
we also account for the nonadiabatic effects, which favour the growth of the
magnetic field. Stars with a magnetic field rotate almost as a solid body.
Several of their properties (size of the core, MS lifetimes, tracks,
abundances) are closer to those of models without rotation than with rotation
only. In particular, the observed N/C or N/H excesses in OB stars are better
explained by our previous models with rotation only than by the present models
with magnetic fields that predict no nitrogen excesses. We show that there is a
complex feedback loop between the magnetic instability and the thermal
instability driving meridional circulation. This opens the possibility for
further magnetic models, but at this stage we do not know the relative
importance of the magnetic fields due to the Tayler instability in stellar
interiors.


title: Prevalence of X-ray variability in the Chandra Deep Field South

abstract:
  We studied the X-ray variability of sources detected in the Chandra Deep
Field South (Giacconi et al. 2002), nearly all of which are low to moderate z
AGN (Tozzi et al. 2001). We find that 45% of the sources with >100 counts
exhibit significant variability on timescales ranging from a day up to a year.
The fraction of sources found to be variable increases with observed flux,
suggesting that >90% of all AGNs possess intrinsic variability. We also find
that the fraction of variable sources appears to decrease with increasing
intrinsic absorption; a lack of variability in hard, absorbed AGNs could be due
to an increased contribution of reflected X-rays to the total flux. We do not
detect significant spectral variability in the majority (~70%) of our sources.
In half of the remaining 30%, the hardness ratio is anti-correlated with flux,
mimicking the high/soft-low/hard states of galactic sources. The X-ray
variability appears anti-correlated with the luminosity of the sources, in
agreement with previous studies. High redshift sources, however, have larger
variability amplitudes than expected from extrapolations of their low-z
counterparts, suggesting a possible evolution in the accretion rate and/or size
of the X-ray emitting region. Finally, we discuss some effects that may produce
the observed decrease in the fraction of variable sources from z=0.5 out to
z=2.


title: Reconstructing large running-index inflaton potentials

abstract:
  Recent fits of cosmological parameters by the first year Wilkinson Microwave
Anisotropy Probe (WMAP) measurement seem to favor a primordial scalar spectrum
with a large varying index from blue to red. We use the inflationary flow
equations to reconstruct large running-index inflaton potentials and comment on
current status on the inflationary flow. We find previous negligence of higher
order slow rolling contributions when using the flow equations would lead to
unprecise results.


title:
An INTEGRAL Observation of the Black Hole Transient 4U 1630--47 and the
  Norma Region of the Galaxy

abstract:
  We report on results from a 2003 February INTEGRAL observation of the black
hole candidate (BHC) 4U 1630-47 and the high energy sources in the Norma Region
of the Galaxy and on RXTE and radio observations of 4U 1630-47. To date, there
have been 38 new or previously poorly studied sources found by INTEGRAL (the
``IGR'' sources), and 15 of the IGR sources are in the field of view of our
observation. We detect 12 of the 15 sources, and we speculate that a subset of
the IGR sources may be part of a new population of persistent, hard,
intermediate luminosity X-ray sources. During our observations, 4U 1630-47 was
in an intermediate state with strong soft and hard components, a power-law
photon index of 2.11-2.18, a 4% rms level of timing noise (0.1-10 Hz), and the
source was not detected in the radio band. We discuss the evolution of the
energy spectrum during the 293 ks INTEGRAL observation, and we report on rapid,
high amplitude flaring behavior that has been seen for much of the 2002-2004
outburst.


title:
Discovery of an OVI Emitting Nebula around the Hot White Dwarf KPD
  0005+5106

abstract:
  A survey of diffuse interstellar sight lines observed with the Far
Ultraviolet Spectroscopic Explorer has led to the serendipitous discovery of a
high-ionization nebula around the hot white dwarf KPD 0005+5106. The nebula has
an OVI 1032A surface brightness of up to 25,000 photons/s/cm^2/sr, making it
the brightest region of extended OVI emission in our survey. Photoionization
models using the incident white dwarf continuum successfully reproduce the
observed OVI intensity. The OVI emission arises in the highly ionized inner
region of a planetary nebula around KPD 0005+5106. This newly discovered nebula
may be one member of a class of high-ionization planetary nebulae that are
difficult to detect in the optical, but which can be easily identified in the
ultraviolet.


title:
CIRPASS near-infrared integral-field spectroscopy of massive star
  clusters in the starburst galaxy NGC 1140

abstract:
  [ABRIDGED] We analyse near-infrared integral field spectroscopy of the
central starburst region of NGC 1140, obtained at the Gemini-South telescope
equipped with CIRPASS. Our ~1.45-1.67 um wavelength coverage includes the
bright [Fe II] emission line, as well as high-order Brackett (hydrogen) lines.
While strong [Fe II] emission, thought to originate in the thermal shocks
associated with supernova remnants, is found throughout the galaxy, both Br
12-4 and Br 14-4 emission, and weak CO(6,3) absorption, is predominantly
associated with the northern starburst region. The Brackett lines originate
from recombination processes occurring on smaller scales in (young) HII
regions. The time-scale associated with strong [Fe II] emission implies that
most of the recent star-formation activity in NGC 1140 was induced in the past
35-55 Myr. Based on the spatial distributions of the [Fe II] versus Brackett
line emission, we conclude that a galaxy-wide starburst was induced several
tens of Myr ago, with more recent starburst activity concentrated around the
northern starburst region. This scenario is (provisionally) confirmed by our
analysis of the spectral energy distributions of the compact, young massive
star clusters (YMCs) detected in new and archival broad-band HST images. The
YMC ages in NGC 1140 are all <= 20 Myr, consistent with independently
determined estimates of the galaxy's starburst age, while there appears to be
an age difference between the northern and southern YMC complexes in the sense
expected from our CIRPASS analysis. Our photometric mass estimates of the NGC
1140 YMCs, likely upper limits, are comparable to those of the highest-mass
Galactic globular clusters and to spectroscopically confirmed masses of
(compact) YMCs in other starburst galaxies.


title:
Pulsar Kicks and Spin Tilts in the Close Double Neutron Stars PSR
  J0737-3039, PSR B1534+12 and PSR B1913+16

abstract:
  In view of the recent measurement of the scintillation velocity for PSR
J0737-3039, we examine the complete set of constraints imposed on the pulsar B
natal kicks (magnitude and orientation) and predict the most favorable pulsar
kick velocity and spin tilt for both isotropic and polar kicks. Our analysis
takes into account both currently unknown parameters: the orientation of the
orbital plane on the sky (Omega) and the radial component of the systemic
velocity (V_r). Assuming that the system's peculiar velocity is entirely due to
the second supernova explosion, we find that the system may have crossed the
Galactic plane multiple times since the birth of the second neutron star and
that the post-supernova peculiar velocity could have been as high as 1200km/s.
We also confirm the absolute lower and upper limits on the physical parameters
derived in our earlier study. For specific combinations of the two unknown
parameters Omega and V_r, however, we find much tighter constraints on the
pre-supernova binary configuration and natal kicks imparted to pulsar B, as
well as on the age of system. Once Omega is measured in the coming year, it
will be straightforward to use the results presented here to further constrain
the natal kicks and the spin-tilt predictions. We complete our comprehensive
study and derive similar constraints and spin-tilt predictions for PSR
B1534+12, where the only free parameter is V_r. Lastly, for PSR B1913+16, we
update the progenitor and kick constraints using the measured pulsar spin tilt
and allowing for Roche-lobe overflow from the progenitor of the pulsar
companion.


title:
Keck Spectroscopy of Two Young Globular Clusters in the Merger Remnant
  NGC 3921

abstract:
  Low-resolution UV-to-visual spectra of two candidate globular clusters in the
merger remnant NGC 3921 are presented. These two clusters of apparent magnitude
V = 22.2 (Mv = -12.5) lie at projected distances of ~5 kpc from the center and
move with halo-type radial velocities relative to the local galaxy background.
Their spectra show strong Balmer absorption lines indicative of main-sequence
turnoffs dominated by A-type stars. Comparisons with model-cluster spectra
computed by Bruzual & Charlot and others yield cluster ages in the range of
200-530 Myr, and metallicities about solar to within a factor of three. Given
their small half-light radii (Reff < 5 pc) and ages corresponding to ~100 core-
crossing times, these clusters are gravitationally bound and, hence, indeed
young globulars. Assuming that they had Chabrier-type initial mass functions,
their estimated current masses are 2.3(+-0.1)x10^6 Msun and 1.5(+-0.1)x10^6
Msun, respectively, or roughly half the mass of omegaCen. Since NGC 3921 itself
shows many signs of being a 0.7(+-0.3) Gyr old protoelliptical, these two young
globulars of roughly solar metallicity and their many counterparts observed
with the Hubble Space Telescope provide supporting evidence that, in the
process of forming elliptical-like remnants, major mergers of gas-rich disks
can also increase the number of metal-rich globular clusters. (Abridged)


title:
Comparing the temperatures of galaxy clusters from hydro-N-body
  simulations to Chandra and XMM-Newton observations

abstract:
  Theoretical studies of the physical processes guiding the formation and
evolution of galaxies and galaxy clusters in the X-ray are mainly based on the
results of numerical hydrodynamical N-body simulations, which in turn are often
directly compared to X-ray observations. Although trivial in principle, these
comparisons are not always simple. We demonstrate that the projected
spectroscopic temperature of thermally complex clusters obtained from X-ray
observations is always lower than the emission-weighed temperature, which is
widely used in the analysis of numerical simulations. We show that this
temperature bias is mainly related to the fact that the emission-weighted
temperature does not reflect the actual spectral properties of the observed
source. This has important implications for the study of thermal structures in
clusters, especially when strong temperature gradients, like shock fronts, are
present. Because of this bias, in real observations shock fronts appear much
weaker than what is predicted by emission-weighted temperature maps, and may
even not be detected. This may explain why, although numerical simulations
predict that shock fronts are a quite common feature in clusters of galaxies,
to date there are very few observations of objects in which they are clearly
seen. To fix this problem we propose a new formula, the spectroscopic-like
temperature function, and show that, for temperature larger than 3 keV, it
approximates the spectroscopic temperature better than few per cent, making
simulations more directly comparable to observations.


title: Why does Low-Luminosity AGN Fueling Remain an Unsolved Problem?

abstract:
  Despite many years of effort, observational studies have not found a strong
correlation between the presence of any proposed fueling mechanism and
low-luminosity AGN. After a discussion of the mass requirements for fueling, I
summarize this observational work and provide a number of hypotheses for why
the nature of AGN fueling has remained unresolved. In particular, I stress the
potential importance of the increasing number of candidate fueling mechanisms
with decreasing mass accretion rate, the relevant spatial scales for different
fueling mechanisms, and the lifetime of an individual episode of nuclear
accretion. The episodic AGN lifetime is a particularly relevant complication if
it is comparable to or shorter than the time that the responsible fueling
mechanisms are observationally detectable. I conclude with a number of
relatively accessible areas for future investigation.


title: The evolution of substructure III: the outskirts of clusters

abstract:
  We present an investigation of satellite galaxies in the outskirts of galaxy
clusters taken from a series of high-resolution N-body simulations. We focus on
the so-called "backsplash population", i.e. satellite galaxies that once were
inside the virial radius of the host but now reside beyond it. We find that
this population is significant in number and needs to be appreciated when
interpreting the various galaxy morphology environmental relationships and
decoupling the degeneracy between nature and nurture. Specifically, we find
that approximately half of the galaxies with current clustercentric distance in
the interval 1-2 virial radii of the host are backsplash galaxies which once
penetrated deep into the cluster potential, with 90% of these entering to
within 50% of the virial radius. These galaxies have undergone significant
tidal disruption, loosing on average 40% of their mass. This results in a mass
function for the backsplash population different to those galaxies infalling
for the first time. We further show that these two populations are
kinematically distinct and should be observable within existent spectroscopic
surveys.


title: X1908+075: A Pulsar Orbiting in the Stellar Wind of a Massive Companion

abstract:
  We have observed the persistent but optically unidentified X-ray source
X1908+075 with the PCA and HEXTE instruments on RXTE. The binary nature of this
source was established by Wen, Remillard, & Bradt (2000) who found a 4.4-day
orbital period in results from the RXTE ASM. We report the discovery of 605 s
pulsations in the X-ray flux. The Doppler delay curve is measured and provides
a mass function of 6.1 Msun which is a lower limit to the mass of the binary
companion of the neutron star. The degree of attenuation of the low-energy end
of the spectrum is found to be a strong function of orbital phase. A simple
model of absorption in a stellar wind from the companion star fits the orbital
phase dependence reasonably well and limits the orbital inclination angle to
the range 38 to 72 degrees. These measured parameters lead to an orbital
separation of 60 to 80 lt-s, a mass for the companion star in the range 9-31
Msun, and an upper limit to the size of the companion of ~22 Rsun. From our
analysis we also infer a wind mass loss rate from the companion star of >~ 1.3
x 10^-6 Msun/yr and, when the properties of the companion star and the effects
of photoionization are considered, likely >~ 4 x 10^-6 Msun/yr. Such a high
rate is inconsistent with the allowed masses and radii that we find for a main
sequence or modestly evolved star unless the mass loss rate is enhanced in the
binary system relative to that of an isolated star. We discuss the possibility
that the companion might be a Wolf-Rayet star that could evolve to become a
black hole in 10^4 to 10^5 yr. If so, this would be the first identified
progenitor of a neutron star--black hole binary.


title: On the O II ground configuration energy levels

abstract:
  The most accurate way to measure the energy levels for the O II 2p^3 ground
configuration has been from the forbidden lines in planetary nebulae. We
present an analysis of modern planetary nebula data that nicely constrain the
splitting within the ^2D term and the separation of this term from the ground
^4S_{3/2} level. We extend this method to H II regions using high-resolution
spectroscopy of the Orion nebula, covering all six visible transitions within
the ground configuration. These data confirm the splitting of the ^2D term
while additionally constraining the splitting of the ^2P term. The energies of
the ^2P and ^2D terms relative to the ground (^4S) term are constrained by
requiring that all six lines give the same radial velocity, consistent with
independent limits placed on the motion of the O+ gas and the planetary nebula
data.


title: Ultra-Low Iron Abundances in Distant Hot Gas in Galaxy Groups

abstract:
  A new XMM observation of the outer regions of the galaxy group NGC 5044
indicates hot gas iron abundances of only ~0.15 solar between r=0.2 - 0.4
r_vir. While the total baryon mass within the virial radius may be close to the
cosmic mean value observed in rich clusters, the ratio of total iron mass to
optical light in NGC 5044 is about 3 times lower than that in rich clusters.
The remarkably low iron abundance over a large volume of the intergroup gas in
the outer regions of NGC 5044 cannot be easily understood in terms of the
outflow of enriched gas in a group wind during its early history or by the long
term enrichment by the group member galaxies that currently occupy this region.
It is possible that the stars in NGC 5044 did not produce iron with the same
efficiency as in clusters, or the iron resides in non-luminous clouds or stars,
or the entropy of the iron-enriched gas created in early galactic starburst
winds was too high to penetrate the group gas of lower entropy.


title: Patterns in the Outer Parts of Galactic Disks

abstract:
  This paper describes test particle simulations of the response of the outer
parts of Galactic disks to barring and spiral structure. Simulations are
conducted for cold Mestel disks and warm quasi-exponential disks with
completely flat rotation curves, subjected to pure quadrupoles and logarithmic
spirals. Even though the starting velocity distributions are smooth, the
end-points of the bar simulations show bimodality and multi-peaked structures
at locations near the outer Lindblad resonance (OLR), although spirality can
make this smoother. The growth of a bar may cause the disk isophotes to become
boxy at the OLR, as stars accummulate particularly along the minor axis. The
growth of a bar is also accompanied by substantial heating of the disk stars
near the OLR. For the growth of a $10^{10} M_{\rm \odot}$ bar, the radial
velocity dispersion is typically quadrupled for initially cold disks (initial
\sigmau $\sim 10$ \kms), and typically doubled for disks with final \sigmau
$\sim 45$ \kms. Simulations performed of the growth and dissolution of bars
give very similar results, demonstrating that the heat once given to disk stars
is very difficult to remove.


title: Neutrino Opacities in Nuclear Matter

abstract:
  Neutrino-matter cross sections and interaction rates are central to the
core-collapse supernova phenomenon and, very likely, to the viability of the
explosion mechanism itself. In this paper, we describe the major neutrino
scattering, absorption, and production processes that together influence the
outcome of core collapse and the cooling of protoneutron stars. One focus is on
energy redistribution and many-body physics, but our major goal is to provide a
useful resource for those interested in supernova neutrino microphysics.


title: Unveiling the Formation of Massive Galaxies

abstract:
  Massive galaxies, such as nearby ellipticals, have relatively low number
densities, yet they host the majority of the stellar mass in the universe.
Understanding their origin is a central problem of galaxy formation. Age dating
of stellar populations found in modern ellipticals, and observations of star
formation in high redshift galaxies, allow us to determine roughly when these
systems formed. These age diagnostics however do not tell us what triggered
star formation, or how galaxies form as opposed to simply when. Recent analyses
of the structures of z > 2 ultraviolet selected galaxies reveal that major
galaxy mergers are a likely method for forming some massive galaxies. There are
however galaxy populations at high redshift (z > 2), namely infrared and
sub-millimeter bright systems, whose evolutionary relationship to modern
ellipticals is still uncertain. An improved characterization of these and other
high redshift galaxy populations is achievable with large infrared imaging and
spectroscopic surveys.


title:
Universality of the subsolar mass distribution from critical
  gravitational collapse

abstract:
  Self-similarity induced by critical gravitational collapse is used as a
paradigm to probe the mass distribution of subsolar objects. At large mass
(solar mass and above) there is widespread agreement as to both the form and
parameter values arising in the mass distribution of stellar objects. At
subsolar mass there is still considerable disagreement as to the qualitative
form of the mass distribution, let alone the specific parameter values
characterizing that distribution.
  For the first time, the paradigm of critical gravitational collapse is
applied to several concrete astrophysical scenarios to derive robust
qualitative features of the subsolar mass distribution. We further contrast
these theoretically derived ideas with the observational situation. In
particular, we demonstrate that at very low mass the distribution is given by a
power law, with an exponent opposite in sign to that observed in the high-mass
regime. The value of this low-mass exponent is in principle calculable via
dynamical systems theory applied to gravitational collapse. Qualitative
agreement between theory, numerical experiments, and observational data is
good, though quantitative issues remain troublesome.


title:
Infrared Observations of the Candidate LBV 1806-20 & Nearby Cluster
  Stars

abstract:
  We report near-infrared photometry, spectroscopy, and speckle imaging of the
hot, luminous star we identify as candidate LBV 1806-20. We also present
photometry and spectroscopy of 3 nearby stars, which are members of the same
star cluster containing LBV 1806-20 and SGR 1806-20. The spectroscopy and
photometry show that LBV 1806-20 is similar in many respects to the luminous
``Pistol Star'', albeit with some important differences. They also provide
estimates of the effective temperature and reddening of LBV 1806-20, and
confirm distance estimates, leading to a best estimate for the luminosity of
this star of $> 5 \times 10^6 L_{\odot}$. The nearby cluster stars have
spectral types and inferred absolute magnitudes which confirm the distance (and
thus luminosity) estimate for LBV 1806-20. If we drop kinematic measurements of
the distance ($15.1 ^{+1.8}_{-1.3}$ kpc), we have a lower limit on the distance
of $>9.5$ kpc, and on the luminosity of $>2 \times 10^6 L_{\odot}$, based on
the cluster stars. If we drop both the kinematic and cluster star indicators
for distance, an ammonia absorption feature sets yet another lower limit to the
distance of $>5.7$ kpc, with a corresponding luminosity estimate of $>7 \times
10^5 L_{\odot}$ for the candidate LBV 1806-20. Furthermore, based on very high
angular-resolution speckle images, we determine that LBV 1806-20 is not a
cluster of stars, but is rather a single star or binary system. Simple
arguments based on the Eddington luminosity lead to an estimate of the total
mass of LBV 1806-20 (single or binary) exceeding $190 M_{\odot}$. We discuss
the possible uncertainties in these results, and their implications for the
star formation history of this cluster.


title: The 1000 Brightest HIPASS Galaxies: HI Properties

abstract:
  (abridged) We present the HIPASS Bright Galaxy Catalog (BGC) which contains
the 1000 HI-brightest galaxies in the southern sky as obtained from the HI
Parkes All-Sky Survey (HIPASS). The selection of the brightest sources is based
on their HI peak flux density (Speak > 116 mJy) as measured from the spatially
integrated HIPASS spectrum. The derived HI masses range from about 10^7 to 4 x
10^10 Msun. While the BGC (z < 0.03) is complete in Speak, only a subset of
about 500 sources can be considered complete in integrated HI flux density (FHI
> 25 JY km/s). The HIPASS BGC contains a total of 158 new redshifts and yields
no evidence for a population of "free-floating" intergalactic HI clouds without
associated optical counterparts. HIPASS provides a clear view of the local
large-scale structure. The dominant features in the sky distribution of the BGC
are the Supergalactic Plane and the Local Void. In addition, one can clearly
see the Centaurus Wall which connects via the Hydra and Antlia clusters to the
Puppis filament. Some previously hardly noticed galaxy groups stand out quite
distinctively in the HI sky distribution. Several new structures are seen for
the first time, not only behind the Milky Way.


title: A comparison of Rosseland-mean opacities from OP and OPAL

abstract:
  Monochromatic opacities from the Opacity Project (OP) (Seaton et al.) have
been augmented by hitherto missing inner-shell contributions (Badnell &
Seaton). OP Rosseland-mean opacities are compared with results from OPAL
(Iglesias & Rogers) for the elements H, He, C, O, S and Fe. Overall, there is
good agreement between OP and OPAL Rosseland-mean opacities for the 6-elements,
but there are some differences. In particular, recent work (Bahcall et al.) has
shown that helioseismology measurements give a very accurate value for the
depth of the solar convection zone and that solar models give agreement with
that value only if opacities there are about 7% larger than OPAL values. For
the 6-element mix, here, we obtain Rosseland-mean opacities to be larger than
OPAL by 5%.