title:
Using color photometry to separate transiting exoplanets from false
  positives

abstract:
  The radial velocity technique is currently used to classify transiting
objects. While capable of identifying grazing binary eclipses, this technique
cannot reliably identify blends, a chance overlap of a faint background
eclipsing binary with an ordinary foreground star. Blends generally have no
observable radial velocity shifts, as the foreground star is brighter by
several magnitudes and therefore dominates the spectrum, but their combined
light can produce events that closely resemble those produced by transiting
exoplanets.
  The radial velocity technique takes advantage of the mass difference between
planets and stars to classify exoplanet candidates. However, the existence of
blends renders this difference an unreliable discriminator. Another difference
must therefore be utilized for this classification -- the physical size of the
transiting body. Due to the dependence of limb darkening on color, planets and
stars produce subtly different transit shapes. These differences can be
relatively weak, little more than 1/10th the transit depth. However, the
presence of even small color differences between the individual components of
the blend increases this difference. This paper will show that this color
difference is capable of discriminating between exoplanets and blends reliably,
theoretically capable of classifying even terrestrial-class transits, unlike
the radial velocity technique.


title: Statistical physics for complex cosmic structures

abstract:
  Cosmic structures at large scales represent the earliest and most extended
form of matter condensation. In this lecture we review the application of the
methods and concepts of modern statistical physics to these structures. This
leads to a new perspective in the field which can be tested by the many new
data which are appearing in the near future. In particular, galaxy structures
show fractal correlation up to the present observational limits. The cosmic
microwave background radiation, which should trace the initial conditions from
which these structures have emerged through gravitational dynamics, is instead
extremely smooth. Understanding the relation between the complex galaxy
structures and the smooth microwave background radiation represents an
extremely challenging problem in the field of structure formation.


title: Solar X-rays as Signature for New Particles

abstract:
  Massive axions of the Kaluza-Klein type, created inside the solar core, can
be gravitationally trapped by the Sun itself in orbits inside/outside the Sun,
where they accumulate over cosmic times. Their radiative decay can give rise to
various solar phenomena, like the celebrated solar coronal heating, which lacks
a conventional explanation since its first observation in 1939. Such and other
recent observations favour the existence of a halo of exotic particles near the
Sun. X-ray telescopes can provide novel and important information. The
underlying solar axion scenario is presented in details in ref.'s [4,15]


title: DarkSUSY: Computing Supersymmetric Dark Matter Properties Numerically

abstract:
  The question of the nature of the dark matter in the Universe remains one of
the most outstanding unsolved problems in basic science. One of the best
motivated particle physics candidates is the lightest supersymmetric particle,
assumed to be the lightest neutralino - a linear combination of the
supersymmetric partners of the photon, the Z boson and neutral scalar Higgs
particles. Here we describe DarkSUSY, a publicly-available advanced numerical
package for neutralino dark matter calculations. In DarkSUSY one can compute
the neutralino density in the Universe today using precision methods which
include resonances, pair production thresholds and coannihilations. Masses and
mixings of supersymmetric particles can be computed within DarkSUSY or with the
help of external programs such as FeynHiggs, ISASUGRA and SUSPECT. Accelerator
bounds can be checked to identify viable dark matter candidates. DarkSUSY also
computes a large variety of astrophysical signals from neutralino dark matter,
such as direct detection in low-background counting experiments and indirect
detection through antiprotons, antideuterons, gamma-rays and positrons from the
Galactic halo or high-energy neutrinos from the center of the Earth or of the
Sun. Here we describe the physics behind the package. A detailed manual will be
provided with the computer package.


title: The environment of Low Surface Brightness Galaxies

abstract:
  Using the Early Data Release of the Sloan Digital Sky Survey (SDSS) we
investigated the clustering properties of Low Surface Brightness (LSB) galaxies
in comparison to normal, High Surface Brightness (HSB) galaxies. We selected
LSB galaxies and HSB galaxies with well measured redshifts from the SDSS data
base and performed three-dimensional neighbour counting analysis within spheres
of radii between 0.8 Mpc and 8.0 Mpc. As a second analysis method we used an
N-th neighbour analysis with N varying from one to ten galaxies. Our results
show significant differences between the galaxy densities of LSB galaxies and
HSB galaxies on scales from 2 to 5 Mpc. At scales larger than 5 Mpc LSB and HSB
galaxies share the same clustering properties. In the pie-slice diagrams the
LSB galaxies appear to favour the inner rims of filaments as defined by the HSB
galaxies, with a couple of LSB galaxies even being located inside the voids.
Our results support the idea of gas-rich LSB galaxies forming and developing in
low density regions without many galaxy interactions and just now reaching the
filaments of the large scale structure.


title: Cosmological Markov Chain Monte Carlo simulation with Cmbeasy

abstract:
  We introduce a Markov Chain Monte Carlo simulation and data analysis package
for the cosmological computation package Cmbeasy. We have taken special care in
implementing an adaptive step algorithm for the Markov Chain Monte Carlo in
order to improve convergence. Data analysis routines are provided which allow
to test models of the Universe against up-to-date measurements of the Cosmic
Microwave Background, Supernovae Ia and Large Scale Structure. The
observational data is provided with the software for convenient usage. The
package is publicly available as part of the Cmbeasy software at
www.cmbeasy.org.


title:
A faint red stellar halo around an edge-on disc galaxy in the Hubble
  Ultra Deep Field

abstract:
  We analyse the detailed structure of a highly-inclined (i>~80 degrees) disc
galaxy which lies within the Hubble Ultra Deep Field (UDF). The unprecedented
depth of the UDF data allow disc and extraplanar emission to be reliably traced
to surface brightness levels of mu_{V,i,z}~29-30 mag/arcsec^2 (corresponding to
rest-frame equivalents of mu_{g,r,i}~28-29 mag/arcsec^2) in this redshift
z=0.32 system. We detect excess emission above the disc which is characterised
by a moderately-flattened (b/a~0.6) power-law (I proportional to R^(-2.6)). The
structure and colour of this component are very similar to the stellar halo
detected in an SDSS stacking analysis of local disc galaxies (Zibetti, White
and Brinkmann 2004) and lend support to the idea that we have detected a
stellar halo in this distant system. Although the peculiar colours of the halo
are difficult to understand in terms of normal stellar populations, the
consistency found between the UDF and SDSS analyses suggests that they cannot
be easily discounted.


title:
Optical and X-ray observations of the neutron star soft X-ray transient
  XTE J1709-267

abstract:
  We report on the discovery of the optical counterpart to the neutron star
soft X-ray transient (SXT) XTE J1709-267 in outburst and quiescence. We further
report the detection of type I bursts in RXTE data obtained during an outburst
of the source in 2002. These bursts show a precursor event before the onset of
the main burst event, reminiscent of photospheric radius expansion bursts.
Sifting through the archival RXTE data for the burster 4U 1636-53 we found a
nearly identical burst with precursor in 4U 1636-53. A comparison of this burst
to true photospheric radius expansion bursts in 4U 1636-53 leads us to conclude
that these bursts-with-precursor do not reach the Eddington limit. We further
report on the analysis of a 22.4 ksec observation of XTE J1709-267 obtained
with the Chandra satellite when the source was in quiescence. We found that the
source has a soft quiescent spectrum which can be fit well by an absorbed black
body or neutron star atmosphere model. A power law contributes less than 10 per
cent to the 0.5-10 keV unabsorbed flux of (1.0+-0.3)x10^-13 erg cm^-2 s^-1.
This flux is the same within the errors as the flux measured right after the
outburst in 2002, indicating that the quiescent flux was reached within a few
weeks after the outburst. Finally, we compared the power-law fractional
contribution to the unabsorbed 0.5-10 keV luminosity for neutron star SXTs in
quiescence for which the distance is well-known. We find that the power-law
contribution is low only when the source quiescent luminosity is close to
\~1-2x10^33 erg s^-1. Both at higher and lower values the power-law
contribution to the 0.5-10 keV luminosity increases. We discuss how models for
the quiescent X-ray emission can explain these trends.(Abridged)


title: First Insights into the SWIRE Galaxy Populations

abstract:
  We characterize the SWIRE galaxy populations in the SWIRE validation field
within the Lockman Hole, based on the 3.6-24$\mu$ Spitzer data and deep
U,g',r',r' optical imaging within an area ~1/3 sq. deg for ~16,000
Spitzer-SWIRE sources. The entire SWIRE survey will discover over 2.3 million
galaxies at 3.6$\mu$m and almost 350,000 at 24$\mu$m; ~70,000 of these will be
5-band 3.6-24$\mu$ detections. The colors cover a broad range, generally well
represented by redshifted spectral energy distributions of known galaxy
populations, however significant samples of unusually blue objects in the
[3.6-4.5]$\mu$m color are found, as well as many objects very red in the
3.6-24$\mu$m mid-IR. Nine of these are investigated and are interpreted as
star-forming systems, starbursts and AGN from z=0.37 to 2.8, with luminosities
from L$_{IR}$=10$^{10.3}$ to 10$^{13.7}$ L$_{\odot}$


title:
A Search for Discrete X-ray Spectral Features in a Sample of Bright
  Gamma-ray Burst Afterglows

abstract:
  (abridged) We present uniform, detailed spectral analyses of gamma-ray burst
(GRB) X-ray afterglows observed with ASCA, Beppo-SAX, Chandra, and XMM-Newton,
and critically evaluate the statistical significances of X-ray emission and
absorption features in these spectra. The sample consists of 21 X-ray afterglow
observations up to and including that of GRB 040106 with spectra of sufficient
statistical quality to allow meaningful line searches, chosen here somewhat
arbitrarily to be detections with more than 100 total (source plus background)
counts. This sample includes all nine X-ray afterglows with published claims of
line detections. Moderate resolution spectra are available for 16 of the 21
sources, and for the remaining five the Chandra transmission grating
spectrometers obtained high-resolution data. All of the data are available from
the public archive. We test a simple hypothesis in which the observed spectra
are produced by a power-law continuum model modified by photoelectric
absorption by neutral material both in our Galaxy and possibly also local to
the burst. As a sample, these afterglow spectra are consistent with this
relatively simple model. However, since the chi-squared statistic is not
sensitive to weak and/or localized fluctuations, we have performed Monte Carlo
simulations to search for discrete features and to estimate their
significances. In all but a few cases, the observed deviations are entirely
consistent with statistical fluctuations such as those typically observed in
spectra with a low number of counts.


title: Kinematics of two dwarf galaxies in the NGC 6946 group

abstract:
  We present high velocity resolution (~ 1.6 km/s) Giant Meterwave Radio
Telescope (GMRT) HI 21 cm synthesis images of the dwarf galaxies KK98 250 and
KK98 251, as well as optical broad band images of KK98 250. We find that,
despite being faint (M_B <-14), both galaxies have regular velocity fields. In
both cases the velocity fields are consistent with rigid body rotation. We
derive rotation curves for the galaxies and fit mass models to them. For both
galaxies, we find acceptable fits using isothermal halos while NFW halos
provide a poor fit. Finally, we compile from literature a sample of galaxies
with HI synthesis observations and I band magnitudes. From this sample we find,
in agreement with earlier studies (which used single dish HI data), that dwarf
galaxies tend to lie below the I band Tully-Fisher relation defined by brighter
galaxies.


title:
Comparison of Radio Observations and Numerical Simulations of the Radio
  Lobes of Cygnus A

abstract:
  We present a comparison of radio observations of the archetypal powerful
radio galaxy Cygnus A and 2-D numerical hydrodynamical simulations. We
characterize some global trends in the observed radio properties and compare
them with the properties of a simulated radio source. The numerical results are
the following. Jets propagating in a constant density atmosphere will
decelerate with time. Thus, the estimated dynamical age of the source will be
greater than the actual age of the source. For a source similar to Cygnus A the
difference will be about a factor of 2. The second moment gives an accurate
representation of the "true" width of the simulated source. The Gaussian FWHM
tends to be about 40% larger than the true width and can be systematically in
error if the surface brightness exhibits multiple peaks. We suggest that the
ratio of the Gaussian FWHM to the second moment may be a diagnostic of the
emissivity profile in the lobes. The simulations can qualitatively reproduce
the overall observed morphology and the behavior of the cross-sections in
surface brightness, the decline in surface brightness with distance from the
hot spots, and the width of the lobes. This suggests that the 2-D simulations
give a reasonable representation of the properties of Cygnus A.


title: Clustering and Proto-Clusters in the Early Universe

abstract:
  The clustering properties of clusters, galaxies and AGN as a function of
redshift are briefly discussed. It appears that extremely red objects at z ~ 1,
and objects with J-K > 1.7 and photometric redshifts 2 < z_phot < 4 are highly
clustered, indicating that a majority of these objects constitutes the
progenitors of nearby ellipticals. Similarly clustered seem luminous radio
galaxies at z\sim 1, indicating that these objects comprise a short lived phase
in the lifetime of these red objects. The high level of clustering furthermore
suggests that distant powerful radio galaxies (e.g. z>2) might be residing in
the progenitors of nearby clusters -- proto-clusters. A number of observational
projects targetting fields with distant radio galaxies, including studies of
Lya and Ha emitters, Lyman break galaxies and (sub)mm and X-ray emitters, all
confirm that such radio galaxies are located in such proto-clusters. Estimates
of the total mass of the proto-clusters are similar to the masses of local
clusters. If the total star formation rate which we estimate for the entire
proto-clusters is sustained up to z~1, the metals in the hot cluster gas of
local clusters can easily be accounted for.


title: SNEWS: The SuperNova Early Warning System

abstract:
  This paper provides a technical description of the SuperNova Early Warning
System (SNEWS), an international network of experiments with the goal of
providing an early warning of a galactic supernova.


title:
ATLAS vs. NextGen model atmospheres: a combined analysis of synthetic
  spectral energy distributions

abstract:
  We carried out a critical appraisal of the two theoretical models, Kurucz'
ATLAS9 and PHOENIX/NextGen, for stellar atmosphere synthesis. Our tests relied
on the theoretical fit of SEDs for a sample of 334 target stars along the whole
spectral-type sequence. The best-fitting physical parameters of stars allowed a
calibration of the temperature and bolometric scale. The main conclusions of
our analysis are: i) the fitting accuracy of both theoretical libraries
drastically degrades at low Teff; ii) comparing with empirical calibrations,
both ATLAS and NextGen fits tend to predict slightly warmer Teff, but ATLAS
provides in general a sensibly better fit; iii) there is a striking tendency of
NextGen to label target stars with an effective temperature and surface gravity
in excess with respect to ATLAS. This is a consequence of some ``degeneracy''
in the solution space, partly induced by the different input physics and
geometry constraints. A different T(\tau) vertical structure of stellar
atmosphere seems also required for NextGen synthetic SEDs in order to better
account for limb-darkening effects in cool stars, as supported by the recent
observations of the EROS BLG2000-5 microlensing event.


title: The Chandra Fornax Survey - I: The Cluster Environment

abstract:
  We present the first results of a deep Chandra survey of the inner 1 degree
of the Fornax cluster of galaxies. Ten 50 ksec pointings were obtained in a
mosaic centered on the giant elliptical galaxy NGC 1399 at the nominal cluster
center. Emission and temperature maps of Fornax are presented, and an initial
study of 771 detected X-ray point sources is made. Regions as small as 100pc
are resolved. The intra-cluster gas in Fornax exhibits a highly asymmetric
morphology and temperature structure, dominated by a 180 kpc extended ``plume''
of low surface brightness, cool, ~1 keV) gas to the North-East of NGC 1399 with
a sharper edge to the South West. The elliptical galaxy NGC 1404 also exhibits
a cool halo of X-ray gas within the cluster, with a highly sharpened leading
edge as it presumably falls into the cluster, and a cometary-like tail. We
estimate that some ~200-400 point sources are physically associated with
Fornax. Confirming earlier works, we find that the globular cluster population
in NGC 1399 is highly X-ray active, extending to globulars which may in fact be
intra-cluster systems. We have also found a remarkable correlation between the
location of giant and dwarf cluster galaxies and the presence of X-ray
counterparts, such that systems inhabiting regions of low gas density are more
likely to show X-ray activity. Not only does this correlate with the asymmetry
of the intra-cluster gas but also with the axis joining the center of Fornax to
an infalling group 1 Mpc to the South-West. We suggest that Fornax may be
experiencing an intergalactic ``headwind'' due to motion relative to the
surrounding large-scale structure.


title: Formation of the Black Holes in the Highest Redshift Quasars

abstract:
  The recent discovery of luminous quasars up to a redshift z=6.43 has renewed
interest in the formation of black holes massive enough to power quasars. If
black holes grow by Eddington-limited gas accretion with a radiative efficiency
of at least 10%, the time required to grow from a stellar black hole to ~10^9
msun is ~10^9 years, close to the age of the universe at z=6. Black hole
mergers may accelerate the rate of mass growth, but can also completely eject
black holes from halo centers owing to the gravitational wave recoil effect.
Recently, Haiman concluded that black hole ejections likely do not allow black
holes to grow to ~10^9 msun by z=6.43. We reexamine this problem and show that,
by using a different halo escape velocity, accounting for the dependence of the
recoil velocity on the black hole binary mass ratio and spins, and allowing
seed black holes to form in all halos down to virial temperatures of 2000 K,
black hole masses may reach ~10^9 msun as early as z=9 starting from stellar
seeds, without super-Eddington accretion. In this particular case, we find that
these massive black holes form from the merger of ~10^4 stellar black holes
formed in low-mass halos at z~20, which must all grow close to the maximum
Eddington rate over most of the time available from their birth to z~6. The
alternative is that black holes can grow more rapidly by super-Eddington
accretion.


title: Present-Day Growth of Black Holes and Bulges: the SDSS Perspective

abstract:
  We investigate the accretion-driven growth of supermassive black holes in the
low-redshift Universe using 23,000 ``Type 2'' AGN and the complete sample of
123,000 galaxies in the SDSS from which they were drawn. We use the stellar
velocity dispersions of the early type galaxies and AGN hosts to estimate their
black hole masses and we use the AGN [OIII]5007 emission line luminosities to
estimate black hole accretion rates. We find that most present-day accretion
occurs onto black holes with masses < 10E8 Msun that reside in moderately
massive galaxies (M ~ 10E10 to 10E11.5 Msun) with high stellar densities
(~10E8.5 to 10E9.5 Msun/kpc^2) and young stellar populations. The
volume-averaged accretion rates of low mass black holes (<10E7.5 Msun) imply
that this population is growing on a timescale that is comparable to the age of
the Universe. Around half this growth takes place in AGN that are radiating
within a factor of five of the Eddington luminosity. Such systems are rare,
making up only 0.2% of the low mass black hole population at the present day.
The rest of the growth occurs in lower luminosity AGN. The growth timescale is
more than two orders of magnitude longer for the population of the most massive
black holes in our sample. The volume averaged ratio of star formation to black
hole accretion in bulge-dominated galaxies is ~1000, in remarkable agreement
with the observed ratio of stellar mass to black hole mass in nearby galaxy
bulges. We conclude: a) that bulge formation and black hole formation are
tightly coupled, even in present-day galaxies; and b) that the evolution of the
AGN luminosity function documented in recent optical and x-ray surveys is
driven by a decrease in the characteristic mass scale of accreting black holes.


title:
The formation of bulges and black holes: lessons from a census of active
  galaxies in the SDSS

abstract:
  We examine the relationship between galaxies, supermassive black holes and
AGN using a sample of 22,000 narrow-emission-line AGN drawn from a a sample of
122,000 galaxies from the Sloan Digital Sky Survey. We have studied how AGN
host properties compare with those of normal galaxies and how they depend on
the luminosity of the active nucleus. We find that AGN reside in massive
galaxies and have distributions of sizes and concentrations that are similar to
those of the early-type galaxies in our sample. The host galaxies of
low-luminosity AGN have stellar populations similar to normal early-types. The
hosts of high-luminosity AGN have much younger mean stellar ages and a
significant fraction have experienced recent starbursts. High-luminosity AGN
are also found in lower density environments. We use the stellar velocity
dispersions of the AGN hosts to estimate black hole masses and their
[OIII]$\lambda$5007 emission line luminosities to estimate black hole accretion
rates. We find that the volume averaged ratio of star formation to black hole
accretion is ~1000, in remarkable agreement with the observed ratio of stellar
mass to black hole mass in nearby bulges. Our estimated accretion rates imply
that low mass black holes are growing on a timescale that is comparable to the
age of the Universe. The growth timescale increases by more than an order of
magnitude for the most massive black holes in our sample. We conclude that the
evolution of the AGN luminosity function is driven by a decrease in the
characteristic mass scale of actively accreting black holes.


title:
Stellar masses, star formation rates, metallicities and AGN properties
  for 200,000 galaxies in the SDSS Data Release Two (DR2)

abstract:
  By providing homogeneous photometric and spectroscopic data of high quality
for very large and objectively selected samples of galaxies, the Sloan Digital
Sky Survey allows statistical studies of the physical properties of galaxies
and AGN to be carried out at an unprecedented level of precision and detail.
Here we publicly release catalogues of derived physical properties for 211,894
galaxies, including 33,589 narrow-line AGN. These are complete samples with
well understood selection criteria drawn from the normal galaxy spectroscopic
sample in the second SDSS public data release (DR2). We list properties
obtained from the SDSS spectroscopy and photometry using modelling techniques
presented in papers already published by our group. These properties include:
stellar masses; stellar mass-to-light ratios; attenuation of the starlight by
dust; indicators of recent major starbursts; current total and specific
star-formation rates, both for the regions with spectroscopy and for the
galaxies as a whole; gas-phase metallicities; AGN classifications based on the
standard emission line ratio diagnostic diagrams and AGN [OIII] emission line
luminosities. We also list our own measurements of absorption line indices and
emission line fluxes from which these quantities were derived, together with a
few quantities from the standard SDSS pipelines which play an important role in
our work. Many other observed properties of these galaxies can be obtained from
the SDSS DR2 catalogues themselves. We will add further physical properties to
this release site as the relevant papers are accepted for publication.
Catalogies containing these parameters may be accessed at
http://www.mpa-garching.mpg.de/SDSS/.


title:
Detection of the Main Sequence Turn-off of a Newly Discovered Milky Way
  Halo Structure in the Triangulum-Andromeda Region

abstract:
  An upper main sequence (MS) and main-sequence turn-off (MSTO) feature appears
in the color-magnitude diagram (CMD) of a large area photometric survey of the
southern half of M31 stretching to M33. Imaging in the Washington M,T_2,DDO51
photometric system allows us to remove the background M31/M33 giants from our
CMD and more clearly define the dwarf star feature, which has an MSTO near M ~
20.5. The corresponding stellar population shows little density variation over
the 12 X 6 square degree area of the sky sampled and is of very low surface
brightness, >32 mag/arcsec^2. We show that this feature is not the same as a
previously identified, MS+MSTO in the foreground of the Andromeda Galaxy that
has been associated with the tidal stream ringing the Milky Way disk at less
than half the distance. Thus, the new stellar system is a separate, more
distant entity, perhaps a segment of tidal debris from a disrupted satellite
galaxy. It is most likely related to the structure with similar distance,
location and density uniformity seen as an excess of K and M giants in the Two
Micron All-Sky Survey reported in the companion paper by Rocha-Pinto et al.
(2004).


title: Spitzer Infrared Spectrograph Observations of M, L, and T Dwarfs

abstract:
  We present the first mid-infrared spectra of brown dwarfs, together with
observations of a low-mass star. Our targets are the M3.5 dwarf GJ 1001A, the
L8 dwarf DENIS-P J0255-4700, and the T1/T6 binary system epsilon Indi Ba/Bb. As
expected, the mid-infrared spectral morphology of these objects changes rapidly
with spectral class due to the changes in atmospheric chemistry resulting from
their differing effective temperatures and atmospheric structures. By taking
advantage of the unprecedented sensitivity of the Infrared Spectrograph on the
Spitzer Space Telescope we have detected the 7.8 micron methane and 10 micron
ammonia bands for the first time in brown dwarf spectra.


title: The Spitzer Space Telescope Mission

abstract:
  The Spitzer Space Telescope, NASA's Great Observatory for infrared astronomy,
was launched 2003 August 25 and is returning excellent scientific data from its
Earth-trailing solar orbit. Spitzer combines the intrinsic sensitivity
achievable with a cryogenic telescope in space with the great imaging and
spectroscopic power of modern detector arrays to provide the user community
with huge gains in capability for exploration of the cosmos in the infrared.
The observatory systems are largely performing as expected and the projected
cryogenic lifetime is in excess of 5 years. This paper summarizes the on-orbit
scientific, technical and operational performance of Spitzer. Subsequent papers
in this special issue describe the Spitzer instruments in detail and highlight
many of the exciting scientific results obtained during the first six months of
the Spitzer mission.


title:
Charge-exchange-induced perturbations of ion and atom distribution
  functions in the heliospheric interface

abstract:
  Various hydrodynamic models of the heliospheric interface have been presented
meanwhile, numerically simulating the interaction of the solar wind plasma
bubble with the counterstreaming partially ionized interstellar medium. In
these model approaches the resulting interface flows are found by the use of
hydrodynamic simulation codes trying to consistently describe the dynamic and
thermodynamic coupling of the different interacting fluids of protons, H-atoms
and pick-up ions. Within such approaches, the fluids are generally expected to
be correctly described by the three lowest velocity moments, i.e., by shifted
Maxwellians. We shall show that in these approaches the charge-exchange-induced
momentum coupling is treated in an unsatisfactory representation valid only at
supersonic differential flow speeds. Though this flaw can be removed by an
improved coupling term, we shall further demonstrate that the assumption of
shifted Maxwellians in some regions of the interface is insufficiently well
fulfilled both for H-atoms and protons. Using a Boltzmann-kinetic description
of the proton- and H-atom- distribution functions coupled by charge exchange
processes we emphasize the fact that non-negligible deviations from shifted
Maxwellians are generated in the interface. This has to be taken into account
when interpreting inner heliospheric measurements in terms of interstellar
parameters.


title: Magnetic Fields and Faraday Rotation in Clusters of Galaxies

abstract:
  We present a numerical approach to investigate the relationship between
magnetic fields and Faraday rotation effects in clusters of galaxies. We can
infer the structure and strength of intra-cluster magnetic fields by comparing
our simulations with the observed polarization properties of extended cluster
radio sources such as radio galaxies and halos. We find the observations
require a magnetic field which fluctuates over a wide range of spatial scales
(at least one order of magnitude). If several polarized radio sources are
located at different projected positions in a galaxy cluster, as is the case
for A119, detailed Faraday rotation images allow us to constrain both the
magnetic field strength and the slope of the power spectrum. Our results show
that the standard analytic expressions applied in the literature overestimate
the cluster magnetic field strengths by a factor of about 2. We investigate the
possible effects of our models on beam depolarization of radio sources whose
radiation traverses the magnetized intracluster medium. Finally, we point out
that radio halos may provide important information about the spatial power
spectrum of the magnetic field fluctuations on large scales. In particular,
different values of the index of the power spectrum produce very different
total intensity and polarization brightness distributions.


title: The estimation of the SZ effects with unbiased multifilters

abstract:
  In this work we study the performance of linear multifilters for the
estimation of the amplitudes of the thermal and kinematic Sunyaev-Zel'dovich
effects. We show that when both effects are present, estimation of these
effects with standard matched multifilters is intrinsically biased. This bias
is due to the fact that both signals have basically the same spatial profile.
We find a new family of multifilters related to the matched multifilters that
cancel this systematic bias, hence we call them Unbiased Matched Multifilters.
We test the unbiased matched multifilters and compare them with the standard
matched multifilters using simulations that reproduce the future Planck
mission's observations. We find that in the case of the standard matched
multifilters the systematic bias in the estimation of the kinematic
Sunyaev-Zel'dovich effect can be very large, even greater than the statistical
error bars. Unbiased matched multifilters cancel effectively this kind of bias.
In concordance with other works in the literature, our results indicate that
the sensitivity and resolution of Planck will not be enough to give reliable
estimations of the kinematic Sunyaev-Zel'dovich of individual clusters.
However, since the estimation with the unbiased matched multifilters is not
intrinsically biased, it can be possible to use them to statistically study
peculiar velocities in large scales using large sets of clusters.


title: Massive Black Holes in Star Clusters. I. Equal-mass clusters

abstract:
  In this paper we report results of collisional N-body simulations of the
dynamical evolution of equal-mass star clusters containing a massive central
black hole. Each cluster is composed of between 5,000 to 180,000 stars together
with a central black hole which contains between 0.2% to 10% of the total
cluster mass.
  We find that for large enough black hole masses, the central density follows
a power-law distribution with slope \rho \sim r^{-1.75} inside the radius of
influence of the black hole, in agreement with predictions from earlier Fokker
Planck and Monte Carlo models. The tidal disruption rate of stars is within a
factor of two of that derived in previous studies. It seems impossible to grow
an intermediate-mass black hole (IMBH) from a M \le 100 Msun progenitor in a
globular cluster by the tidal disruption of stars, although M = 10^3 Msun IMBHs
can double their mass within a Hubble time in dense globular clusters. The same
is true for the supermassive black hole at the centre of the Milky Way.
  Black holes in star clusters will feed mainly on stars tightly bound to them
and the re-population of these stars causes the clusters to expand, reversing
core-collapse without the need for dynamically active binaries. Close
encounters of stars in the central cusp also lead to an increased mass loss
rate in the form of high-velocity stars escaping from the cluster. A companion
paper will extend these results to the multi-mass case.


title:
Effect of BCS pairing on entrainment in neutron superfluid current in
  neutron star crust

abstract:
  The relative current density $n^i$ of conduction neutrons in a neutron star
crust beyond the neutron drip threshold can be expected to be related to the
corresponding particle momentum covector $p_i$ by a linear relation of the form
$n^i=K^{ij}p_j$ in terms of a physically well defined mobility tensor $K^{ij}$.
This result is describable as an ``entrainment'' whose effect - wherever the
crust lattice is isotropic - will simply be to change the ordinary neutron mass
m to an effective mass $m_\star$ such that in terms of the relevant number
density n of unconfined neutrons we shall have $K^{ij}=n/m_\star\gamma^{ij}$.
In a preceding analysis based on an independent particle treatment using Bloch
boundary conditions to obtain the distribution of energy $E_k$ and associated
group velocity $v_k^i=\partial E_k/\partial\hbar k_i$ as a function of
wavenumber $k_i$, it was shown that the mobility tensor would be given by
$K^{ij}\propto\int d^3 k v_k^i v_k^j\delta\{E_k-\mu\}$, where $\mu$ is the
Fermi energy. Using the approach due to Bogoliubov, it is shown here that the
effect of BCS pairing with an energy gap \Delta_F and corresponding
quasiparticle energy function \EE_k=\sqrt{(E_k-\mu)^2+\Delta_F^2}$ will just be
to replace the Dirac distributional integrand by a smoother distribution :
$K^{ij}\propto \int d^3 k v_k^i v_k^j \Delta_F^2 /\EE^3_k$. It is also shown
how the pairing condensation gives rise to superfluidity in the technical sense
of providing (meta) stability against resistive perturbations for a current
that is not too strong (its momentum $p_i$ must be small enough to give $2|p_i
v_k^i|<\EE_k^2/|E_k-\mu|$ for all modes). It is concluded that the prediction
of a very large effective mass enhancement in the middle layers of the crust
will not be significantly affected by the pairing mechanism.


title:
Do weak magnetic fields prevent hydrogen from accreting onto metal-line
  white dwarf stars?

abstract:
  The widely accepted assumption is that metals detected in the spectra of a
few cool helium-rich white dwarfs cannot be of primordial origin and therefore
must be accreted from the interstellar medium. However, the observed abundances
of hydrogen are much too low to be compatible with the high accretion rates
inferred from metal accretion. Hydrogen accretion is therefore suppressed
compared to metal accretion. The hypothesis most widely discussed as cause for
this ``hydrogen screening'' is the propeller mechanism: Metals are accreted in
the form of grains onto a slowly rotating, weakly magnetized white dwarf,
whereas ionized hydrogen is repelled at the Alfv\'en radius. We have obtained
circular polarization spectra of the helium-rich white dwarfs GD 40
(WD0300-013) and L745-46A (WD0738-172) -- which both show strong metal lines as
well as hydrogen -- in order to search for signatures of a weak magnetic field.
The magnetic field strengths necessary for the propeller mechanism to work in
these stars are at least 144000 G and 3000 G, respectively. Whereas L745-46A
might have a magnetic field of about $-$6900 G no magnetic field could be found
with an upper limit for the field strength of 4000 G (with 99% confidence) for
GD 40.


title:
Quasi-simultaneous XMM-Newton and VLA observation of the non-thermal
  radio emitter HD\168112 (O5.5III(f^+))

abstract:
  We report the results of a multiwavelength study of the non-thermal radio
emitter HD168112 (O5.5III(f^+)). The detailed analysis of two
quasi-simultaneous XMM-Newton and VLA observations reveals strong variability
of this star both in the X-ray and radio ranges. The X-ray observations
separated by five months reveal a decrease of the X-ray flux of ~30%. The radio
emission on the other hand increases by a factor 5-7 between the two
observations obtained roughly simultaneously with the XMM-Newton pointings. The
X-ray data reveal a hard emission that is most likely produced by a thermal
plasma at kT ~2-3 keV while the VLA data confirm the non-thermal status of this
star in the radio waveband. Comparison with archive X-ray and radio data
confirms the variability of this source in both wavelength ranges over a yet
ill defined time scale. The properties of HD168112 in the X-ray and radio
domain point towards a binary system with a significant eccentricity and an
orbital period of a few years. However, our optical spectra reveal no
significant changes of the star's radial velocity suggesting that if HD168112
is indeed a binary, it must be seen under a fairly low inclination.


title: Massive Black Holes in Star Clusters. II. Realistic Cluster Models

abstract:
  We have followed the evolution of multi-mass star clusters containing massive
central black holes through collisional N-body simulations done on GRAPE6. Each
cluster is composed of between 16,384 to 131,072 stars together with a black
hole with an initial mass of M_BH=1000 Msun. We follow the evolution of the
clusters under the combined influence of two-body relaxation, stellar mass-loss
and tidal disruption of stars.
  The (3D) mass density profile follows a power-law distribution \rho \sim
r^{-\alpha} with slope \alpha=1.55. This leads to a constant density profile of
bright stars in projection, which makes it highly unlikely that core collapse
clusters contain intermediate-mass black holes (IMBHs). Instead globular
clusters containing IMBHs can be fitted with standard King profiles.
  The disruption rate of stars is too small to form an IMBH out of a M_BH
\approx 50 Msun progenitor black hole, unless a cluster starts with a central
density significantly higher than what is seen in globular clusters.
  Kinematical studies can reveal 1000 Msun IMBHs in the closest clusters. IMBHs
in globular clusters are only weak X-ray sources since the tidal disruption
rate of stars is low and the star closest to the IMBH is normally another black
hole. For globular clusters, dynamical evolution can push compact stars near
the IMBH to distances small enough that they become detectable through
gravitational radiation. If 10% of all globular clusters contain IMBHs,
extragalactic globular clusters could be one of the major sources for {\it
LISA}. (abridged)


title: Cosmological parameters and the WMAP data revisited

abstract:
  Several recent papers have made claims about the detection of an asymmetric
distribution of large scale power in the cosmic microwave background anisotropy
as measured by the WMAP satellite. In this paper, we investigate how the
estimates of particular cosmological parameters vary when inferred from power
spectra computed separately on the northern and southern hemispheres in three
frames of reference. We focus our investigation on the three specific
parameters to which the analysis is most sensitive, the spectral index n, the
amplitude of fluctuations A and the optical depth tau. When using a gaussian
prior on the spectral index n centred at n=1 with a flat prior on the optical
depth tau, the preferred value for the optical depth (derived in the reference
frame of maximum asymmetry) in the north is tau=0 with upper limit tau<0.08,
whereas in the south we find tau=0.24 +0.06/-0.07 (68% confidence level). The
latter result is inconsistent with tau=0 at the 2 sigma level. The estimated
optical depth of tau=0.17 on the (nearly) full sky found by the WMAP
collaboration and confirmed independently here, could thus in large part
originate in structure associated with the southern hemisphere. Furthermore,
putting a prior on tau, we find values of the spectral index which are
inconsistent between the opposite hemispheres. The exact values depend on the
prior on tau. While our results should not be considered more than suggestive,
the significance of the parameter differences in the two hemispheres being
typically of order 2 sigma, if they are confirmed with the higher sensitivity
WMAP 2-year data then it may be necessary to question the assumption of
cosmological isotropy and the conceptual framework within which studies of the
CMB anisotropy are made.


title: The submm properties of GRB host galaxies

abstract:
  Long duration gamma-ray bursts (GRBs) accompany the deaths of some massive
stars and hence, since massive stars are short lived, are a tracer of star
formation activity. Given that GRBs are bright enough to be seen to very high
redshifts, and detected even in dusty environments, they should therefore
provide a powerful probe of the global star formation history of the universe.
The potential of this approach can be investigated via submm photometry of GRB
host galaxies. Submm luminosity also correlates with star formation rate, so
the distribution of host galaxy submm fluxes should allow us to test the two
methods for consistency. Here, we report new JCMT/SCUBA 850 micron measurements
for 15 GRB hosts. Combining these data with results from previous studies we
construct a sample of 21 hosts with <1.4 mJy errors. We show that the
distribution of apparent 850 micron flux densities of this sample is reasonably
consistent with model predictions, but there is tentative evidence of a dearth
of submm bright (>4 mJy) galaxies. Furthermore, the optical/infrared properties
of the submm brightest GRB hosts are not typical of the galaxy population
selected in submm surveys, although the sample size is still small. Possible
selection effects and physical mechanisms which may explain these discrepancies
are discussed.


title:
Impact of the nuclear equation of state on the last orbits of binary
  neutron stars

abstract:
  We present calculations of quasiequilibrium sequences of irrotational binary
neutron stars based on realistic equations of state (EOS) for the whole neutron
star interior. Three realistic nuclear EOSs of various softness and based on
different microscopic models have been joined with a recent realistic EOS of
the crust, giving in this way three different EOSs of neutron-star interior.
Computations of quasiequilibrium sequences are performed within the
Isenberg-Wilson-Mathews approximation to general relativity. For all
evolutionary sequences, the innermost stable circular orbit (ISCO) is found to
be given by mass-shedding limit (Roche lobe overflow). The EOS dependence on
the last orbits is found to be quite important: for two 1.35 M_sol neutron
stars, the gravitational wave frequency at the ISCO (which marks the end of the
inspiral phase) ranges from 800 Hz to 1200 Hz, depending upon the EOS. Detailed
comparisons with 3rd order post-Newtonian results for point-mass binaries
reveals a very good agreement until hydrodynamical effects (dominated by
high-order functions of frequency) become important, which occurs at a
frequency ranging from 500 Hz to 1050 Hz, depending upon the EOS.


title:
Synchrotron Self-Compton Model for Rapid Nonthermal Flares in Blazars
  with Frequency-Dependent Time Lags

abstract:
  We model rapid variability of multifrequency emission from blazars occurring
across the electromagnetic spectrum (from radio to gamma-rays). Lower energy
emission is produced by the synchrotron mechanism, whereas higher energy
emission is due to inverse Compton scattering of the synchrotron emission. We
take into account energy stratification established by particle acceleration at
shock fronts and energy losses due to synchrotron emission. We also consider
the effect of light travel delays for the synchrotron emission that supplies
the seed photons for inverse Compton scattering. The production of a flare is
caused by the collision between a relativistic shock wave and a stationary
feature in the jet (e.g., a Mach disk). The collision leads to the formation of
forward and reverse shocks, which confine two contiguous emission regions
resulting in complex profiles of simulated flares. Simulations of
multifrequency flares indicate that relative delays between the inverse Compton
flares and their synchrotron counterparts are dominated by energy
stratification and geometry of the emitting regions, resulting in both negative
and positive time delays depending on the frequency of observation. Light
travel effects of the seed photons may lead to a noticeable delay of the
inverse Compton emission with respect to synchrotron variability if the line of
sight is almost perfectly aligned with the jet. We apply the model to a flare
in 3C 273 and derive the properties of shocked plasma responsible for the
flare. We show that the pronounced negative time delay between the X-ray and IR
light curves (X-rays peak after the maximum in the synchrotron emission) can be
accounted for if both forward and reverse shocks are considered.


title:
Dynamical models and numerical simulations of incomplete violent
  relaxation

abstract:
  N-body simulations of collisionless collapse have offered important clues to
the construction of realistic stellar dynamical models of elliptical galaxies.
Such simulations confirm and quantify the qualitative expectation that rapid
collapse of a self-gravitating collisionless system, initially cool and
significantly far from equilibrium, leads to incomplete relaxation. In this
paper we revisit the problem, by comparing the detailed properties of a family
of distribution functions derived from statistical mechanics arguments to those
of the products of collisionless collapse found in N-body simulations.


title:
Structure and Colors of Diffuse Emission in the Spitzer Galactic First
  Look Survey

abstract:
  We investigate the density structure of the interstellar medium using new
high-resolution maps of the 8 micron, 24 micron, and 70 micron surface
brightness towards a molecular cloud in the Gum Nebula, made as part of the
Spitzer Space Telescope Galactic First Look Survey. The maps are correlated
with 100 micron images measured with IRAS. At 24 and 70 micron, the spatial
power spectrum of surface brightness follows a power law with spectral index
-3.5. At 24 micron, the power law behavior is remarkably consistent from the
0.2 degree size of our maps down to the 5 arcsecond spatial resolution. Thus,
the structure of the 24 micron emission is self-similar even at milliparsec
scales. The combined power spectrum produced from Spitzer 24 micron and IRAS 25
micron images is consistent with a change in the power law exponent from -2.6
to -3.5. The decrease may be due to the transition from a two-dimensional to
three-dimensional structure. Under this hypothesis, we estimate the thickness
of the emitting medium to be 0.3 pc.


title: Thermal infrared observations of near-Earth asteroid 2002 NY40

abstract:
  We obtained N-band observations of the Apollo asteroid 2002 NY40 during its
close Earth fly-by in August 2002 with TIMMI2 at the ESO 3.6 m telescope. The
photometric measurement allowed us to derive a radiometric diameter of
0.28+/-0.03 km and an albedo of 0.34+/-0.06 through the near-Earth asteroid
thermal model (NEATM) and a thermophysical model (TPM). The values are in
agreement with results from radar data, visual and near-IR observations. In
this first comparison between these two model approaches we found that the
empirical NEATM beaming parameter $\eta$=1.0 corresponds to a thermal inertia
values of about 100 $\mathrm{J m^{-2} s^{-0.5} K^{-1}}$ for a typical range of
surface roughness, assuming an equator-on viewing angle. Our TPM analysis
indicated that the surface of 2002 NY40 consists of rocky material with a thin
or no dust regolith. The asteroid very likely has a prograde sense of rotation
with a cold terminator at the time of our observations. Although both model
approaches can fit the thermal spectra taken at phase angles of 22$^{\circ}$
and 59$^{\circ}$, we did not find a consistent model solution that describes
all pieces of photometric and spectroscopic data. In addition to the 2002 NY40
analysis, we discuss the possibilities to distinguish between different models
with only very few photometric and/or spectroscopic measurements spread over a
range of phase angles.


title:
PSR B0809+74: Understanding Its Perplexing Subpulse-separation (P2)
  Variations

abstract:
  The longitude separation between adjacent drifting subpulses, $P_2$, is
roughly constant for many pulsars. It was then perplexing when pulsar B0809+74
was found to exhibit substantial variations in this measure, both with
wavelength and with longitude position within the pulse window. We analyze
these variations between 40 and 1400 MHz, and we show that they stem primarily
from the incoherent superposition of the two orthogonal modes of polarization.


title:
PSR B1951+32: A Bow Shock-Confined X-ray Nebula, a Synchrotron Knot and
  an Optical Counterpart Candidate

abstract:
  The radio pulsar B1951+32 and the supernova remnant CTB 80 provide a rich
laboratory for the study of neutron stars and supernova remnants. Here, we
present ground-based optical and near-infrared observations of them, along with
X-ray observations with Chandra and a re-analysis of archival data obtained
with the Hubble Space Telescope. The X-ray observations reveal a cometary
pulsar wind nebula which appears to be confined by a bow shock produced by
high-velocity motion of the pulsar, making PSR B1951+32 a rare pulsar
exhibiting both an H alpha bow shock and a shocked X-ray pulsar wind nebula.
The distribution of H alpha and radio continuum emission is indicative of a
contact discontinuity of the shocked pulsar winds and shocked ambient medium at
\~0.05 pc. On the other hand, the optical synchrotron knot of PSR B1951+32
likely has a flat spectrum in the optical and near-infrared wavebands, and our
astrometry is consistent with only one of the two reported optical counterpart
candidates for the pulsar.


title: Looking for dark matter annihilations in dwarf galaxies

abstract:
  We calculate the flux of high energy gamma-rays from annihilation of
neutralino dark matter in the centre of the Milky Way and the three nearest
dwarf spheroidals (Sagittarius, Draco and Canis Major), using realistic models
of the dark matter distribution.


title: SNLS -- the Supernova Legacy Survey

abstract:
  Type Ia supernovae provide direct evidence for an accelerating universe, and
for the existence of "dark energy" driving this expansion. The Supernova Legacy
Survey (SNLS) will deliver many hundreds of SNIa detections, and well-sampled
g'r'i'z' light curves, over the next 5 years. Using these data, we will obtain
a precise measurement of the cosmological parameters (Omega_mass,
Omega_Lambda); our goal is to determine the cosmological equation of state
parameter w to a precision better than +-0.10, and hence test theories for the
origin of the universal acceleration. SNLS uses the CFHT MegaCam imager (400
Megapixels, 1 deg^2) to image four fields around the sky in 4 filters, with
typical time sampling of 3--4 nights. A total of 202 nights of CFHT time has
been allocated over the next 5 years for these observations; a large program of
followup spectroscopy is now underway at VLT, Gemini, Keck, and Magellan. SNLS
has been running since August 2003. There now exist about 330 reliable SN
detections with excellent light curves out to beyond redshift 0.9, of which
about 80 have been spectroscopically identified as Type Ia's. See
http://www.cfht.hawaii.edu/SNLS for up-to-the-minute information on the latest
SN discoveries.


title:
Halpha Morphologies and Environmental Effects in Virgo Cluster Spiral
  Galaxies

abstract:
  We describe the various Halpha morphologies of Virgo Cluster and isolated
spiral galaxies, and associate the Halpha morphologies with the types of
environmental interactions which have altered the cluster galaxies. The spatial
distributions of Halpha and R-band emission are used to divide the star
formation morphologies of the 52 Virgo Cluster spirals into several categories:
normal (37%), anemic (6%), enhanced (6%), and (spatially) truncated (52%).
Truncated galaxies are further subdivided based on their inner star formation
rates into truncated/normal (37%), truncated/compact (6%), truncated/anemic
(8%), and truncated/enhanced (2%). The fraction of anemic galaxies is
relatively small (6-13%) in both environments, suggesting that starvation is
not a major factor in the reduced star formation rates of Virgo spirals. The
majority of Virgo spiral galaxies have their Halpha disks truncated (52%),
whereas truncated Halpha disks are rarer in isolated galaxies (12%). Most of
the Halpha-truncated galaxies have relatively undisturbed stellar disks and
normal-to-slightly enhanced inner disk star formation rates, suggesting that
ICM-ISM stripping is the main mechanism causing the reduced star formation
rates of Virgo spirals. In other galaxies, the Halpha morphologies are more
consistent with a tidal origin or perhaps outer cluster HI accretion. These
results indicate that most Virgo spiral galaxies experience ICM-ISM stripping,
many experience significant tidal effects, and many experience both.
(abridged).


title:
Intracluster Light in Nearby Galaxy Clusters: Relationship to the Halos
  of Brightest Cluster Galaxies

abstract:
  We present a detailed analysis of the surface brightness distribution of the
brightest cluster galaxy (BCG) in each of 24 galaxy clusters at 0.03<z<0.13. We
use two-dimensional profile fitting to model the surface brightness out to
r=300 kpc for each BCG, comparing r^{1/4}, r^{1/n}, and double r^{1/4} models.
We obtain statistically superior fits using a two component model consisting of
a pair of r^{1/4} profiles with independent scale lengths, ellipticities, and
orientations. The two component model can simply reproduce the observed
position angle and ellipticity gradients, which cannot generally be explained
purely by triaxiality. The inner component of our two component model has
properties similar to a typical massive elliptical galaxy and is clearly
associated with the BCG. The outer component is 10-40 times larger in scale,
has ~10 times the total luminosity of the inner component, and exhibits a
steeper <\mu>-r_e relation than that of the elliptical fundamental plane. We
interpret this outer component as a population of intracluster stars tracing
the cluster potential. The two components are strongly aligned
(|\Delta\theta|<10\degr) in roughly 40% of the clusters. When they are not
aligned, the components tend toward high degrees of misalignment, suggesting
that accretion of infalling material may change the orientation of some BCGs
for a time. The extent of the outer component and its similar elongation to
published cluster galaxy distributions indicates that the evolution of the
intracluster light is tied to the cluster as a whole rather than to the BCG.


title: An Observation of the Intermediate Polar XY Arietis with Chandra

abstract:
  Chandra serendipitously observed the eclipsing (80 deg < i < 84 deg)
intermediate polar, XY Arietis (=H0253+193), in two separate but continuous
observations five weeks apart. XY Ari was in a quiescent state during both
observations. We pursue the study of phase-resolved spectra for this system
focusing on the Fe K lines. From the combined and separate data sets, we
readily detect emission lines of iron near 6.4, 6.7, and 6.9 keV at better than
99% significance in contrast to previous results. We confirm the orbit-phased
sinusoidal absorption column behavior first observed with Ginga as well as a
sinusoid-like behavior as a function of spin phase. The presence of the 6.4,
6.7, and 6.9 keV lines requires different ionization states with xi <2 (6.4
keV) and xi \sim$3.5-4 (6.7 and 6.9 keV) that must vary with phase. We also
detect emission lines at 3.25, 4.8, and 5.4 keV that are not instrumental in
origin. The 4.8 keV line may be identified as Ca XIX (4.832 keV) and the 3.25
keV line may be Ar I K, but the 5.4 keV line has no obvious identification.


title: The Abundance and Radial Distribution of Satellite Galaxies

abstract:
  Using detailed mock galaxy redshift surveys (MGRSs) we investigate the
abundance and radial distribution of satellite galaxies. The mock surveys are
constructed using the conditional luminosity function (CLF), and are compared
against data from the 2dFGRS. We use Monte Carlo Markov Chains to explore the
full posterior distribution of the CLF parameter space, and show that the
average relation between light and mass is tightly constrained. The radial
number density distribution of satellite galaxies in the 2dFGRS reveals a
pronounced absence of satellites at small projected separations from their host
galaxies. This is (at least partially) due to the overlap and merging of galaxy
images in the APM catalogue. Because of the resulting close-pair incompleteness
we are unfortunately unable to put meaningful constraints on the radial
distribution of satellite galaxies. Marginalizing over the full CLF parameter
space, we show that in a LCDM concordance cosmology the observed abundances of
host and satellite galaxies in the 2dFGRS indicate a power spectrum
normalization of sigma_8=0.7. The same cosmology but with sigma_8=0.9 is unable
to simultanously match the abundances of host and satellite galaxies. This
confirms our previous conclusions based on the pairwise peculiar velocity
dispersions and the group multipliticy function.


title:
Response of dark matter halos to condensation of baryons: cosmological
  simulations and improved adiabatic contraction model

abstract:
  The cooling of gas in the centers of dark matter halos is expected to lead to
a more concentrated dark matter distribution. The response of dark matter to
the condensation of baryons is usually calculated using the model of adiabatic
contraction, which assumes spherical symmetry and circular orbits. In contrast,
halos in the hierarchical structure formation scenarios grow via multiple
violent mergers and accretion along filaments, and particle orbits in the halos
are highly eccentric. We study the effects of the cooling of gas in the inner
regions of halos using high-resolution cosmological simulations which include
gas dynamics, radiative cooling, and star formation. We find that the
dissipation of gas indeed increases the density of dark matter and steepens its
radial profile in the inner regions of halos compared to the case without
cooling. For the first time, we test the adiabatic contraction model in
cosmological simulations and find that the standard model systematically
overpredicts the increase of dark matter density in the inner 5% of the virial
radius. We show that the model can be improved by a simple modification of the
assumed invariant from M(r)r to M(r_av)r, where r and r_av are the current and
orbit-averaged particle positions. This modification approximately accounts for
orbital eccentricities of particles and reproduces simulation profiles to
within 10-20%. We present analytical fitting functions that accurately describe
the transformation of the dark matter profile in the modified model and can be
used for interpretation of observations.


title:
Candidate Type II Quasars from the Sloan Digital Sky Survey: II. From
  Radio to X-Rays

abstract:
  Type II quasars are luminous AGNs whose central engines and broad-line
regions are obscured by intervening material; such objects only recently have
been discovered in appreciable numbers. We study the multiwavelength properties
of 291 type II AGN candidates (0.3 < z < 0.8) selected based on their optical
emission line properties from the spectroscopic database of the Sloan Digital
Sky Survey. This sample includes about 150 objects luminous enough to be
classified as type II quasars. We matched the sample to the FIRST (20 cm), IRAS
(12-100 micron), 2MASS (JHK_S) and RASS (0.1-2.4 keV) surveys. Roughly 10% of
optically selected type II AGN candidates are radio-loud, comparable to the AGN
population as a whole. About 40 objects are detected by IRAS at 60 micron
and/or 100 micron, and the inferred mid/far-IR luminosities lie in the range nu
L_nu=10^45-3x10^46 erg/sec. Average IR-to-[OIII]5007 ratios of objects in our
sample are consistent with those of other AGNs. Objects from our sample are ten
times less likely to have soft X-ray counterparts in RASS than type I AGNs with
the same redshifts and [OIII]5007 luminosities. The few type II AGN candidates
from our sample that are detected by RASS have harder X-ray spectra than those
of type I AGNs. The multiwavelength properties of the type II AGN candidates
from our sample are consistent with their interpretation as powerful obscured
AGNs.


title:
First mid-infrared spectrum of a faint high-z galaxy: Observations of
  CFRS 14.1157 with the Infrared Spectrograph on the Spitzer Space Telescope

abstract:
  The unprecedented sensitivity of the Infrared Spectrograph on the Spitzer
Space Telescope allows for the first time the measurement of mid-infrared
spectra from 14 to 38 microns of faint high-z galaxies. This unique capability
is demonstrated with observations of sources having 16 micron fluxes of 3.6 mJy
(CFRS 14.1157) and 0.35 mJy (CFRS 14.9025). A spectral-fitting technique is
illustrated which determines the redshift by fitting emission and absorption
features characteristic of nearby galaxies to the spectrum of an unknown
source. For CFRS 14.1157, the measured redshift is z = 1.00+/-0.20 in agreement
with the published result of z = 1.15. The spectrum is dominated by emission
from an AGN, similar to the nucleus of NGC 1068, rather than a typical
starburst with strong PAH emission like M82. Such spectra will be crucial in
characterizing the nature of newly discovered distant galaxies, which are too
faint for optical follow-up.


title: GLAST: Understanding the High Energy Gamma-Ray Sky

abstract:
  We discuss the ability of the GLAST Large Area Telescope (LAT) to identify,
resolve, and study the high energy gamma-ray sky. Compared to previous
instruments the telescope will have greatly improved sensitivity and ability to
localize gamma-ray point sources. The ability to resolve the location and
identity of EGRET unidentified sources is described. We summarize the current
knowledge of the high energy gamma-ray sky and discuss the astrophysics of
known and some prospective classes of gamma-ray emitters. In addition, we also
describe the potential of GLAST to resolve old puzzles and to discover new
classes of sources.


title: The IRAC Shallow Survey

abstract:
  The IRAC shallow survey covers 8.5 square degrees in the NOAO Deep Wide-Field
Survey in Bootes with 3 or more 30 second exposures per position. An overview
of the survey design, reduction, calibration, star-galaxy separation, and
initial results is provided. The survey includes approximately 370,000,
280,000, 38,000, and 34,000 sources brighter than the 5 sigma limits of 6.4,
8.8, 51, and 50 microJy at 3.6, 4.5, 5.8, and 8 microns respectively, including
some with unusual spectral energy distributions.


title: Q0906+6930: The Highest-Redshift Blazar

abstract:
  We report the discovery of a radio-loud flat-spectrum QSO at z=5.47 with
properties similar to those of the EGRET gamma-ray blazars. This source is the
brightest radio QSO at z>5, with a pc-scale radio jet and a black hole mass
estimate >10^{10}M_\odot. It appears to be the most distant blazar discovered
to date. High energy observations of this source can provide powerful probes of
the background radiation in the early universe.


title: Solar Neutrino Measurements

abstract:
  A review of solar neutrino experiments is provided, including experimental
measurements to date and proposed future measurements. Experiments to date have
provided a clear determination that solar neutrinos are undergoing flavor
transformation and that the dominant mechanism for this transformation is
oscillation. The mixing parameters are well defined and limits are placed on
sub-dominant modes. The measurements also provide strong confirmation of solar
model calculations. New experiments under development will study neutrino
oscillation parameters and sub-dominant modes with greater precision and will
investigate solar fluxes further, concentrating primarily on the low energy pp,
$^7$Be, pep and CNO reactions.


title:
Diffuse Galactic continuum gamma rays. A model compatible with EGRET
  data and cosmic-ray measurements

abstract:
  We present a study of the compatibility of some current models of the diffuse
Galactic continuum gamma rays with EGRET data. A set of regions sampling the
whole sky is chosen to provide a comprehensive range of tests. The range of
EGRET data used is extended to 100 GeV. The models are computed with our
GALPROP cosmic-ray propagation and gamma-ray production code. We confirm that
the "conventional model" based on the locally observed electron and nucleon
spectra is inadequate, for all sky regions. A conventional model plus hard
sources in the inner Galaxy is also inadequate, since this cannot explain the
GeV excess away from the Galactic plane. Models with a hard electron injection
spectrum are inconsistent with the local spectrum even considering the expected
fluctuations; they are also inconsistent with the EGRET data above 10 GeV.
  We present a new model which fits the spectrum in all sky regions adequately.
Secondary antiproton data were used to fix the Galactic average proton
spectrum, while the electron spectrum is adjusted using the spectrum of diffuse
emission itself. The derived electron and proton spectra are compatible with
those measured locally considering fluctuations due to energy losses,
propagation, or possibly details of Galactic structure. This model requires a
much less dramatic variation in the electron spectrum than models with a hard
electron injection spectrum, and moreover it fits the gamma-ray spectrum better
and to the highest EGRET energies. It gives a good representation of the
latitude distribution of the gamma-ray emission from the plane to the poles,
and of the longitude distribution. We show that secondary positrons and
electrons make an essential contribution to Galactic diffuse gamma-ray
emission.


title: A Sample of Low Redshift BL Lacs. I. The Radio Data

abstract:
  We present a new sample of 30 nearby (z<0.2) BL Lacs, selected to study the
nuclear as well as the large scale properties of low power radio sources. In
this first paper, we show and discuss new radio data taken with the VLA (19
objects at 1.4 GHz, either in A or C configuration, or both) as well as with
the VLBA (15 sources at 5 GHz). On the kiloparsec scale, all objects exhibit a
compact core and a variety of radio morphologies (jets, halos, secondary
compact components). On the parsec scale, we find weak cores and a few short,
one-sided, jets. From the jet/counter-jet ratio, core dominance, and
synchrotron self Compton model we estimate the intrinsic orientation and
velocity of the jets. The resulting properties of BL Lacs are similar to those
of a parent population composed of FR I radio galaxies.


title:
The All Sky Automated Survey. The Catalog of Variable Stars. III. 12h -
  18h Quarter of the Southern Hemisphere

abstract:
  This paper describes the third part of the photometric data from the 9 x 9
deg ASAS camera monitoring the whole southern hemisphere in V-band. Preliminary
list of variable stars based on observations obtained since January 2001 is
presented. Over 3,200,000 stars brighter than V=15 on 18,000 frames were
analyzed and 10453 were found to be variable (1718 eclipsing, 731 regularly
pulsating, 849 Mira and 7155 other stars). Light curves have been classified
using the improved automated algorithm, which now takes into account 2MASS
colors and IRAS infrared fluxes. Basic photometric properties are presented in
the tables and some examples of thumbnail light curves are printed for
reference. All photometric data are available over the INTERNET at
http://www.astrouw.edu.pl/~gp/asas/asas.html or
http://archive.princeton.edu/~asas


title: Testing the mirror world hypothesis for the close-in extrasolar planets

abstract:
  Because planets are not expected to be able to form close to stars due to the
high temperatures, it has been suggested that the observed close orbiting
($\sim 0.05$ AU) large mass planets ($\sim M_J$) might be mirror worlds --
planets composed predominately of mirror matter. The accretion of ordinary
matter onto the mirror planet (from e.g. the solar wind from the host star)
will make the mirror planet opaque to ordinary radiation with an effective
radius $R_p$. It was argued in a previous paper, astro-ph/0101055, that this
radius was potentially large enough to explain the measured size of the first
transiting close-in extrasolar planet, HD209458b. Furthermore,
astro-ph/0101055, made the rough prediction: $R_p \propto \sqrt{{T_s \over
M_p}}$, where $T_s$ is the surface temperature of the ordinary matter in the
mirror planet and $M_p$ is the mass of the planet (the latter dependence being
the more robust prediction). We compare this prediction with the recently
discovered transiting planets, OGLE-TR-56b and OGLE-TR-113b.


title: The sharp drop in the flux striking the accretion disk

abstract:
  In this paper,We present a simple relativistic approach to analyze the flux
striking the disk which is possibly from a source up the Black hole.The X-ray
source is locate above an accretion disc orbiting around the black hole,this
assumption is invoked by recent studies about iron k$\alpha$. we compute and
arguing that due to the light bending effect near black hole, the flux striking
the disk surface may be very concentrated,which will undoubtable change the
disk's ionization state hence change the iron line's ionization state and
emissivity.Also,Our model may explain the steep power law when modelling the
lines.


title: Evolution and Fragmentation of Wide-Angle Wind Driven Molecular Outflows

abstract:
  We present two dimensional cylindrically symmetric hydrodynamic simulations
and synthetic emission maps of a stellar wind propagating into an infalling,
rotating environment. The resulting outflow morphology, collimation and
stability observed in these simulations have relevance to the study of young
stellar objects, Herbig-Haro jets and molecular outflows. Our code follows
hydrogen gas with molecular, atomic and ionic components tracking the
associated time dependent molecular chemistry and ionization dynamics with
radiative cooling appropriate for a dense molecular gas. We present tests of
the code as well as new simulations which indicate the presence of
instabilities in the wind-blown bubble's swept-up shell.


title: Supermassive black holes from primordial black hole seeds

abstract:
  The observational evidence for a population of quasars powered by
supermassive black holes of mass \geq 10^9 M_sun at redshifts z\geq 6 poses a
great challenge for any model describing the formation of galaxies. Assuming
uninterrupted accretion at the Eddington limit, seed black holes of at least
1000 M_sun are needed at z \approx 15. Here I study whether these seeds could
be primordial black holes (PBHs) which have been produced in the very early
universe by the collapse of primordial density fluctuations. In particular, I
study the expected number densities of PBHs in the relevant mass range for
several classes of spectra of primordial density fluctuations and confront the
results with observational data. While it seems to be possible to produce the
required PBHs with spectra showing large enhancements of fluctuations on a
certain scale, our hypothesis can be clearly disproved for a scale free
spectrum of primordial fluctuations described by a power-law slope consistent
with recent observations.


title: An 850 Micron SCUBA Survey of the HDF-N GOODS Region

abstract:
  The Hubble Deep Field-North (HDF-N) is one of the best studied extragalactic
fields, and ultra-deep optical, radio, X-ray, and mid-infrared wide-field
images are available for this area. Here we present an 850 um survey around the
HDF-N, covering most of the area imaged by the Advanced Camera for Surveys as a
part of the Great Observatories Origins Deep Survey. Our map has 0.4-4 mJy
sensitivities (1 sigma) over an area ~110 arcmin^2 and there are 45 sources
detected at >3 sigma. After correcting the effects of noise, confusion,
incompleteness, and the Eddington bias using Monte Carlo simulations, we find
that the detected 850 $\mu$m sources with fluxes greater than 2 mJy have a
surface density of 3200^+1900_-1000 deg^-2 and account for about 24% to 34% of
the far-infrared extragalactic background light. Using the deep radio
interferometric image and the deep X-ray image, we are able to accurately
locate ~60% of the bright submillimeter (submm) sources. In addition, by
assuming the Arp 220 spectral energy distribution in the submm and radio, we
estimate millimetric redshifts for the radio detected submm sources, and
redshift lower limits for the ones not detected in the radio. Using the
millimetric redshifts of the radio identified sources and spectroscopic and
optical photometric redshifts for galaxies around the submm positions, we find
a median redshift of 2.0 for 11 possibly identified sources, or a lower limit
of 2.4 for the median redshift of our 4 sigma sample.


title: On the excitation of the infrared knots in the HH99 outflow

abstract:
  We present near infrared (IR) spectra (0.98--2.5 mu m) from the group of
Herbig-Haro (HH) objects comprising HH99: a series of knots forming a bow,
HH99B, and a separate knot, HH99A. Observations of H2, [Fe II] and [C I] are
used to constrain shock model parameters and determine the origin of the
emission. Previous work has shown that it is likely that the atomic and ionic
emission arises in regions of higher ionization than the molecular emission. On
the basis of observations, it has often been suggested that the [Fe II] and [C
I] emission could arise, for example, at the apex of a bow shock, with the H2
emission produced in the wings. Accordingly, we have combined models of
C-component and J-type shocks in order to reproduce the observed H2, [Fe II]
and [C I] line spectra. We can account for the H2 emission towards the HH99B
complex by means of J-type shocks with magnetic precursors. We derive shock
velocities of about 30 km s-1 and ages of order 100 yr; the pre-shock gas has a
density of approximately 10^4 cm-3 and the magnetic field is approximately 100
mu G. The J-type shocks required to reproduce the intensities of the observed
[Fe II] and [C I] lines have velocities of 50 km s-1. It is necessary to assume
that Fe has been previously eroded from grains, probably by the earlier passage
of a C-type shock wave. Thus, our analysis supports the view that molecular
outflows are episodic phenomena whose observed emission arises in shock waves.


title: Circumstellar Interaction of Type Ia Supernova SN 2002ic

abstract:
  SN 2002ic is a unique supernova which shows the typical spectral features of
Type Ia supernovae (SNe Ia) near maximum light, but also apparent hydrogen
features that have been absent in SNe Ia. We have calculated hydrodynamical
models for the interaction between the SN Ia ejecta and the H-rich
circumstellar medium (CSM) to reproduce the observed features of SN 2002ic.
Based on our modeling, we suggest that CSM is aspherical (or highly clumpy) and
contains about 4-5 solar masses. Possible progenitor systems of SN 2002ic are
discussed.


title:
Massive planets in FU Orionis discs: implications for thermal
  instability models

abstract:
  FU Orionis are young stellar objects undergoing episodes of enhanced
luminosity, which are generally ascribed to a sudden increase of mass accretion
rate in the surrounding protostellar disc. Models invoking a thermal
instability in the disc are able to reproduce many features of the outburst,
but cannot explain the rapid rise time-scale observed in many cases. Here we
explore the possibility (originally suggested by Clarke & Syer 1996) that the
thermal instability is triggered away from the disc inner edge (at a distance
of $\approx 10R_{\odot}$ from the central protostar) due to the presence of a
massive planet embedded in the disc. We have constructed simple,
one-dimensional, time-dependent models of the disc evolution, taking into
account both the interaction between the disc and the planet, and the thermal
evolution of the disc. We are indeed able to reproduce rapid rise outbursts
(with rise time-scale $\approx 1$ yr), with a planet mass
$M_{\mathrm{s}}=10-15M_{\mathrm{Jupiter}}$. We show that the luminosity and the
duration of the outbursts are increasing functions of planet mass. We also show
that the inward migration of the planet is significantly slowed once it reaches
the radius where it is able to trigger FU Orionis outbursts, thus suggesting
that a single planet may be involved in triggering several outbursts.


title: Lambda Boo stars with composite spectra

abstract:
  We examine the large sample of lambda Boo candidates collected in Table 1 of
Gerbaldi et al. (2003) to see how many of them show composite spectra. Of the
132 lambda Boo candidates we identify 22 which definitely show composite
spectra and 15 more for which there are good reasons to suspect a composite
spectrum. The percentage of lambda Boo candidates with composite spectra is
therefore > 17 and possibly considerably higher. For such stars the lambda Boo
classification should be reconsidered taking into account the fact that their
spectra are composite. We argue that some of the underabundances reported in
the literature may simply be the result of the failure to consider the
composite nature of the spectra. This leads to the legitimate suspicion that
some, if not all, the lambda Boo candidates are not chemically peculiar at all.
A thorough analysis of even a single one of the lambda Boo candidates with
composite spectra, in which the composite nature of the spectrum is duly
considered, which would demonstrate that the chemical peculiarities persist,
would clear the doubt we presently have that the stars with composite spectra
may not be lambda Boo at all.


title:
The bimodal galaxy color distribution: dependence on luminosity and
  environment

abstract:
  We analyse the u-r color distribution of 24346 galaxies with Mr<=-18 and
z<0.08, drawn from the Sloan Digital Sky Survey first data release, as a
function of luminosity and environment. The color distribution is well fit with
two Gaussian distributions, which we use to divide the sample into a blue and
red population. At fixed luminosity, the mean color of the blue (red)
distribution is nearly independent of environment, with a weakly significant
(~3sigma) detection of a trend for colors to become redder by 0.1-0.14
(0.03-0.06) mag with a factor ~100 increase in local density, as characterised
by the surface density of galaxies within a +/-1000 km/s redshift slice. In
contrast, at fixed luminosity the fraction of galaxies in the red distribution
is a strong function of local density, increasing from ~10-30 per cent of the
population in the lowest density environments, to ~70 per cent at the highest
densities. The strength of this trend is similar for both the brightest
(-23<Mr<-22) and faintest (-19<Mr<-18) galaxies in our sample. The fraction of
red galaxies within the virialised regions of clusters shows no significant
dependence on velocity dispersion. Even at the lowest densities explored, a
substantial population of red galaxies exists, which might be fossil groups. We
propose that most star-forming galaxies today evolve at a rate that is
determined primarily by their intrinsic properties, and independent of their
environment. Any environmentally triggered transformations from blue to red
colors must either occur on a short timescale, or preferentially at high
redshift, to preserve the simple Gaussian nature of the color distribution. The
mechanism must be effective for both bright and faint galaxies.


title: On the Enhanced Interstellar Scattering Toward B1849+005

abstract:
  (Abridged) This paper reports new Very Large Array (VLA) and Very Long
Baseline Array (VLBA) observations of the extragalactic source B1849+005 at
frequencies between 0.33 and 15 GHz and the re-analysis of archival VLA
observations at 0.33, 1.5, and 4.9 GHz. The structure of this source is complex
but interstellar scattering dominates the structure of the central component at
least to 15 GHz. An analysis of the phase structure functions of the
interferometric visibilities shows the density fluctuations along this line of
sight to be anisotropic (axial ratio = 1.3) with a frequency-independent
position angle, and having an inner scale of roughly a few hundred kilometers.
The anisotropies occur on length scales of order 10^{15} cm (D/5 kpc), which
within the context of certain magnetohydrodynamic turbulence theories indicates
the length scale on which the kinetic and magnetic energy densities are
comparable. A conservative upper limit on the velocity of the scattering
material is 1800 km/s. In the 0.33 GHz field of view, there are a number of
other sources that might also be heavily scattered. Both B1849+005 and PSR
B1849+00 are highly scattered, and they are separated by only 13'. If the lines
of sight are affected by the same ``clump'' of scattering material, it must be
at least 2.3 kpc distant. However, a detailed attempt to account for the
scattering observables toward these sources does not produce a self-consistent
set of parameters for such a clump. A clump of H\alpha emission, possibly
associated with the H II region G33.418-0.004, lies between these two lines of
sight, but it seems unable to account for all of the required excess
scattering.


title: ATLAS and SYNTHE under Linux

abstract:
  We have successfully ported under GNU Linux ATLAS 9, the widely used stellar
atmosphere modeling code, as well as both the SYNTHE suite of programs, its
``companion'' for spectral synthesis, and WIDTH, used to derive chemical
abundances from equivalent widths of spectral lines. The porting has been
realized by using the Intel Fortran Compiler. Our aim was to port the codes
with the minimum possible amount of modifications: full compatibility with the
VMS version has been maintained, along with all the codes functionalities.
Dramatic improvement in calculation speed with respect to the VMS version has
been achieved. The full suite of codes is intended to be freely available to
anyone.


title:
Resolution of Distance Ambiguities of Inner Galaxy Massive Star
  Formation Regions II

abstract:
  We report simultaneous H110alpha and H2CO line observations with the NRAO
Green Bank Telescope toward 72 H II regions in the SPITZER/GLIMPSE survey area
(|l| = 10 deg - 65 deg and |b| </= 1 deg). We used the H110alpha line to
establish the velocity of the H II regions and H2CO absorption lines to
distinguish between near and far distances. We examined the projected location
of H II regions whose distance ambiguities have been resolved (in this work and
other similar studies) in the Galactic plane and in a longitude-velocity
diagram for a recognizable spiral arm pattern. Although the highest density of
points in the position-position plot approximately follows the spiral arms
proposed by Taylor and Cordes (1993), the dispersion is still about as large as
the separation between their proposed arms. The longitude-velocity plot shows
an increase in the density of sources at the points where the spiral arm loci
proposed by Taylor and Cordes (1993) are approaching the locus of tangent point
velocities and a lower density between the arm loci. However, it is not
possible to trace spiral arms over significant segments of Galactic longitude
in the longitude-velocity plot. We conclude that a very large number of H II
regions in combination with more sophisticated Galactic rotation models will be
required to obtain a more continuous spiral pattern from kinematic studies of H
II regions than from fully sampled surveys of H I or CO.


title:
Results from the Wide Angle Search for Planets Prototype (WASP0) I:
  Analysis of the Pegasus Field

abstract:
  WASP0 is a prototype for what is intended to become a collection of
wide-angle survey instruments whose primary aim is to detect extra-solar
planets transiting across the face of their parent star. The WASP0 instrument
is a wide-field (9-degree) 6.3cm aperture F/2.8 Apogee 10 CCD camera (2Kx2K
chip, 16-arcsec pixels) mounted piggy-back on a commercial telescope. We
present results from analysis of a field in Pegasus using the WASP0 camera,
including observations of the known transiting planet around HD 209458. We also
present details on solving problems which restrict the ability to achieve
photon limited precision with a wide-field commercial CCD. The results
presented herein demonstrate that millimag photometry can be obtained with this
instrument and that it is sensitive enough to detect transit due to extra-solar
planets.


title:
The hydrostatic equilibrium and Tsallis equilibrium for self-gravitating
  systems

abstract:
  Self-gravitating systems are generally thought to behavior non-extensively
due to the long-range nature of gravitational forces. We obtain a relation
between the nonextensive parameter q of Tsallis statistics, the temperature
gradient and the gravitational potential based on the equation of hydrostatic
equilibrium of self-gravitating systems. It is suggested that the nonextensive
parameter in Tsallis statistics has a clear physical meaning with regard to the
non-isothermal nature of the systems with long-range interactions and Tsallis
equilibrium distribution for the self-gravitating systems describes the
property of hydrostatic equilibrium of the systems.


title:
Simultaneous Chandra and RXTE Spectroscopy of the Microquasar
  H~1743-322: Clues to Disk Wind and Jet Formation from a Variable Ionized
  Outflow

abstract:
  We observed the bright phase of the 2003 outburst of the Galactic black hole
candidate H 1743-322 in X-rays simultaneously with Chandra and RXTE on four
occasions. The Chandra/HETGS spectra reveal narrow, variable (He-like) Fe XXV
and (H-like) Fe XXVI resonance absorption lines. In the first observation, the
Fe XXVI line has a FWHM of 1800 +/- 400 km/s and a blue-shift of 700 +/- 200
km/s, suggesting that the highly ionized medium is an outflow. Moreover, the Fe
XXV line is observed to vary significantly on a timescale of a few hundred
seconds in the first observation, which corresponds to the Keplerian orbital
period at approximately 1 E+4 gravitational radii. Our models for the
absorption geometry suggest that a combination of geometric effects and
changing ionizing flux are required to account for the large changes in line
flux observed between observations, and that the absorption likely occurs at a
radius less than 1 E+4 radii for a 10 Msun black hole. Viable models for the
absorption geometry include cyclic absorption due to an accretion disk
structure, absorption in a clumpy outflowing disk wind, or possibly a
combination of these two. If the wind in H 1743-322 has unity filling factor,
the highest implied mass outflow rate is 20 percent of the Eddington mass
accretion rate. This wind may be a hot precursor to the Seyfert-like,
outflowing "warm absorber" geometries recently found in the Galactic black
holes GX 339-4 and XTE J1650-500. We discuss these findings in the context of
ionized Fe absorption lines found in the spectra of other Galactic sources, and
connections to warm absorbers, winds, and jets in other accreting systems.


title: The Metallicity Distribution in the Outer Halo of M33

abstract:
  We present the results of deep I and V-band photometry of the halo stars near
the southeast minor axis of the Local Group spiral galaxy M33. An (I,V-I)
color-magnitude diagram distinctly reveals the red giant branch stars at the
bright end of the color-magnitude diagram. A luminosity function in the I-band
which utilizes a background field to remove the contaminating effects of
Galactic foreground stars and distant, unresolved galaxies reveals the presence
of the tip of the red giant branch at (m-M)_{I}=20.70. Assuming an absolute
magnitude of the tip of the red giant branch of M_{I,TRGB}=-4.1 and a
foreground reddening of E(V-I)=0.054, the distance modulus of M33 is determined
to be (m-M)=24.72 (880 kpc). The metallicity distribution function derived by
interpolating between evolutionary tracks of red giant branch models is
dominated by a relatively metal poor stellar population, with a mean
metallicity of [m/H]=-0.94 or [Fe/H]=-1.24. We fit a leaky-box chemical
enrichment model to the halo data, which shows that the halo is well
represented by a single-component model with an effective yield of
y_{eff}=0.0024.


title: A more informative picture of the HST Ultra Deep Field

abstract:
  The Hubble Space Telescope has obtained some of its well-deserved impact by
producing stunning three-color (RGB) pictures from three-band imaging data.
Here we produce a new RGB representation of the $I$, $V$, and $B$ bandpass
images of the HST Ultra Deep Field (HUDF). Our representation is based on
principles set forth elsewhere (Lupton et al 2004, PASP, 116, 133--137). The
principal difference between our RGB representation of the data and the more
traditional representation provided by the Space Telescope Science Institute is
that the (necessarily) nonlinear transformation between data values and RGB
values is done in a color-preserving (i.e., hue- and saturation-preserving)
way. For example, if one of the image pixel values saturates the dynamic range
of the RGB representation, all three of the R, G, and B values in the
representation are truncated such that the hue and saturation of the pixel is
the same as it would have been if the pixel had had lower flux but the same
astronomical color. This, in effect, makes the bright parts of the
representation an informative color map, not "whited out" as they are in
traditional representations. For the HUDF, this difference is seen best in the
centers of bright galaxies, which show significant detail not visible in the
more traditional representation.


title:
Intrinsic alignment-lensing interference as a contaminant of cosmic
  shear

abstract:
  Cosmic shear surveys have great promise as tools for precision cosmology, but
can be subject to systematic errors including intrinsic ellipticity
correlations of the source galaxies. The intrinsic alignments are believed to
be small for deep surveys, but this is based on intrinsic and lensing
distortions being uncorrelated. Here we show that the gravitational lensing
shear and intrinsic shear need not be independent: correlations between the
tidal field and the intrinsic shear cause the intrinsic shear of nearby
galaxies to be correlated with the gravitational shear acting on more distant
galaxies. We estimate the magnitude of this effect for two simple intrinsic
alignment models: one in which the galaxy ellipticity is linearly related to
the tidal field, and one in which it is quadratic in the tidal field as
suggested by tidal torque theory. The first model predicts a
gravitational-intrinsic (GI) correlation that can be much greater than the
intrinsic-intrinsic (II) correlation for broad redshift distributions, and that
remains when galaxies pairs at similar redshifts are rejected. The second
model, in its simplest form, predicts no gravitational-intrinsic correlation.
In the first model and assuming a normalization consistent with recently
claimed detections of intrinsic correlations we find that the GI correlation
term can exceed the usual II term by >1 order of magnitude and the intrinsic
correlation induced B-mode by 2 orders of magnitude. These interference effects
can suppress the lensing power spectrum for a single broad redshift bin by of
order ~10% at z_s=1 and ~30% at z_s=0.5.


title: The Off-nuclear Starbursts In NGC 4038/4039 (The Antennae Galaxies)

abstract:
  Imaging of the Antennae galaxies (NGC 4038/4039) with the Infrared Array
Camera (IRAC) aboard the Spitzer Space Telescope reveals large concentrations
of star forming activity away from both nuclei of the two merging galaxies.
These images confirm earlier findings based on ISO data with lower angular
resolution. The short wavelength emission shows numerous compact sources
identified as stellar clusters. At the longer wavelengths, bright, more
amorphous and filamentary features correlate well with the known distributions
of denser gas, warm dust, and HII regions. There are also fainter, more diffuse
components at all wavelengths that permeate the entire region and extend into
the two tidal tails. Non-stellar dust emission dominates the 5.8 and 8.0 micron
images, accounting for as much as 79% of the light at 5.8 micron and 95% at 8
micron, averaged over the entire galaxy. Assuming that the non-stellar emission
traces star formation, the IRAC data provide a view into the total underlying
star forming activities unaffected by obscuration. Using the flux ratio of
non-stellar to stellar emission as a guide, we map the local star formation
rate in the Antennae and compare that to similar measurements in both normal
and infrared-luminous galaxies. This rate in the active regions is found to be
as high as those seen in starburst and some ultra-luminous infrared galaxies on
``per unit mass'' basis. The two galactic centers actually have lower star
forming rates than the off-nuclear regions despite the presence of abundant
dense gas and dust, suggesting that the latter is a necessary but not
sufficient condition for on-going star formation.


title: The apparent size of GRB afterglows as a test of the Fireball model

abstract:
  Taylor et al. (2004) reported recently on the first direct measurement of the
apparent size of a GRB afterglow. Here we confront these observations with the
predictions of the fireball model. We use a simple model to study numerically
the evolution of the fireball and determine its apparent size, starting at the
early spherical expansion phase through the jet break and into the Newtonian
regime. We perform these calculations on the background of a uniform
interstellar medium and a massive stellar wind environment. We find that the
calculated apparent size at the time of the measurements taken by Taylor et al.
depends only weakly on the chosen parameters (the jet opening angle, the
energy, and the external density profile). Thus it is reassuring that the only
possible outcome of the model, within the plausible range of parameters, agrees
very well with the data. These measurements therefore present us with a strong
test of possible GRB models, which the fireball model passes successfully.


title: Where are the High Velocity Clouds in Local Group Analogs?

abstract:
  High-velocity clouds (HVCs) are clouds of HI seen around the Milky Way with
velocities inconsistent with Galactic rotation, have unknown distances and
masses and controversial origins. One possibility is that HVCs are associated
with the small dark matter halos seen in models of galaxy formation and
distributed at distances of 150 kpc - 1 Mpc. We report on our attempts to
detect the analogs to such putative extragalactic clouds in three groups of
galaxies similar to our own Local Group using the ATNF Parkes telescope and
Compact Array. Eleven dwarf galaxies were found, but no HI clouds lacking stars
were detected. Using the population of compact HVCs around the Milky Way as a
template, we find that our non-detection of analogs implies that they must be
clustered within 160 kpc of the Milky Way (and other galaxies) with an average
HI mass <4x10^5 M(sun) at the 95% confidence level. This is in accordance with
recent limits derived by other authors. If our groups are true analogs to the
Local Group, then this makes the original Blitz et al. and Braun & Burton
picture of HVCs residing out to 1 Mpc from the Milky Way extremely unlikely.
The total HI mass in HVCs, < 10^8 M(sun), implies that there is not a large
reservoir of neutral hydrogen waiting to be accreted onto the Milky Way. Any
substantial reservoir of baryonic matter must be mostly ionized or condensed
enough as to be undetectable.