title: The GZK Feature in the Spectrum of Ultra High Energy Cosmic Rays

abstract:
  The detection of the GZK feature in the cosmic ray spectrum, resultingfrom
the production of pions by ultra-high energy protons scattering off the cosmic
microwave background (CMB), can shed light on the mysterious sources of these
high energy particles. Using numerical simulations we developed for the
propagation of Ultra High Energy Cosmic Rays (UHECR) in the CMB we determine
the statistical significance of the GZK feature in the spectrum of UHECR
measured by AGASA and HiRes and we show that, with the small sample of events
with energies of the order of 10^20 eV detected thus far, an accurate and
statistically significant determination of the GZK feature is not possible. The
data from these two experiments are best fit by two different injection spectra
in the region below 10^20 eV, and a comparison of the spectra suggests the
resence of about a 30% systematic errors in the relative energy determination.
Correcting for these systematics, the two experiments are best fit by the same
injection spectrum in the region below 10^20 eV, while above this threshold
they maintain their disagreement, but only at the 2 sigma level. These results
clearly show the need for much larger experiments such as Auger, EUSO and OWL,
that can increase the number of detected events by one or two orders of
magnitude making the determination of the GZK feature feasible.


title:
Dust emission in the far-IR as a star formation tracer at z=0:
  systematic trends with luminosity

abstract:
  We investigate if dust emission in the far-IR continuum provides a robust
estimate of star formation rate (SFR) for a nearby, normal late-type galaxy. We
focus on the ratio of the 40--1000 micron luminosity (L_dust) to the far-UV
(0.165 micron luminosity, which is connected to recent episodes of star
formation. Available total photometry at 0.165, 60, 100 and 170 micron limits
the statistics to 30 galaxies, which, however, span a large range in observed
(and, thus, attenuated by dust) K-band (2.2 micron) luminosity, morphology and
inclination (i). This sample shows that the ratio of L_dust to the observed
far-UV luminosity depends not only on i, as expected, but also on morphology
and, in a tighter way, on observed K-band luminosity. We find that L_dust/L_FUV
is proportional to e^(-tau_K) (alpha+0.62) (L_K)^(0.62), where L_FUV and L_K
are the unattenuated stellar luminosities in far-UV and K, respectively, and
alpha is the ratio of the attenuation optical depths at 0.165 micron (tau_FUV)
and 2.2 micron (tau_K). This relation is to zeroth order independent of i and
morphology. It may be further expressed as L_dust/L_FUV proportional to
(L_K)^delta, where delta = 0.61 - 0.02 alpha, under the
observationally-motivated assumption that, for an average inclination,
e^(-tau_K) is proportional to (L_K)^(-0.02). We adopt calculations of two
different models of attenuation of stellar light by internal dust to derive
solid-angle averaged values of alpha. We find that delta is positive and
decreases towards 0 from the more luminous to the less luminous galaxies. This
means that there is no universal ratio of far-IR luminosity to unattenuated
far-UV luminosity for nearby, normal late-type galaxies. (Abridged)


title: Direct Detection of a CME-Associated Shock in LASCO White Light Images

abstract:
  The LASCO C2 and C3 coronagraphs recorded a unique coronal mass ejection on
April 2, 1999. The event did not have the typical three-part CME structure and
involved a small filament eruption without any visibile overlying streamer
ejecta. The event exhibited an unusually clear signature of a wave propagating
at the CME flanks. The speed and density of the CME front and flanks were
consistent with the existence of a shock. To better establish the nature of the
white light wave signature, we employed a simple MHD simulation using the LASCO
measurements as constraints. Both the measurements and the simulation strongly
suggest that the white light feature is the density enhancement from a
fast-mode MHD shock. In addition, the LASCO images clearly show streamers being
deflected when the shock impinges on them. It is the first direct imaging of
this interaction.


title:
Origin of PSRs with 0.1 < P < 0.3 s and 5 x 1E5 < Tau < 1E7 yr after the
  second Supernova explosion in HMXBs

abstract:
  The origin of a part of the single pulsars with relatively low magnetic
fields B < 1E12 G and with characteristic times Tau < 1E7 yr is established.
Such pulsars occur as a result of the disruption of High Mass X-ray Binary
Systems after a second Supernova explosion. In these binaries mass accretion
onto the surface of X-ray pulsars leads to the decrease of the magnetic field
from its initial value B ~ 1E12-1E13 G down to B < 1E12 G similar to the
processes in Low Mass X-ray Binaries.


title: Scaling behavior in a stochastic self-gravitating system

abstract:
  A system of stochastic differential equations for the velocity and density of
a classical self-gravitating matter is investigated by means of the field
theoretic renormalization group. The existence of two types of large-scale
scaling behavior, associated to physically admissible fixed points of the
renormalization-group equations, is established. Their regions of stability are
identified and the corresponding scaling dimensions are calculated in the
one-loop approximation (first order of the epsilon expansion). The velocity and
density fields have independent scaling dimensions. Our analysis supports the
importance of the rotational (nonpotential) components of the velocity field in
the formation of those scaling laws.


title: Stochastic Self-Similar and Fractal Universe

abstract:
  The structures formation of the Universe appears as if it were a classically
self-similar random process at all astrophysical scales. An agreement is
demonstrated for the present hypotheses of segregation with a size of
astrophysical structures by using a comparison between quantum quantities and
astrophysical ones. We present the observed segregated Universe as the result
of a fundamental self-similar law, which generalizes the Compton wavelength
relation. It appears that the Universe has a memory of its quantum origin as
suggested by R.Penrose with respect to quasi-crystal. A more accurate analysis
shows that the present theory can be extended from the astrophysical to the
nuclear scale by using generalized (stochastically) self-similar random
process. This transition is connected to the relevant presence of the
electromagnetic and nuclear interactions inside the matter. In this sense, the
presented rule is correct from a subatomic scale to an astrophysical one. We
discuss the near full agreement at organic cell scale and human scale too.
Consequently the Universe, with its structures at all scales (atomic nucleus,
organic cell, human, planet, solar system, galaxy, clusters of galaxy, super
clusters of galaxy), could have a fundamental quantum reason. In conclusion, we
analyze the spatial dimensions of the objects in the Universe as well as
spacetime dimensions. The result is that it seems we live in an El Naschie's E
infinity Cantorian spacetime; so we must seriously start considering fractal
geometry as the geometry of nature, a type of arena where the laws of physics
appear at each scale in a self--similar way as advocated long ago by the
Swedish school of astrophysics.


title:
Temporal evolution of radiation from a plasma blob with constant
  deceleration: application to gamma-ray bursts

abstract:
  It has been widely accepted that relativistic effects have to be used for
modelling the wide classes of events associated with active galactic nuclei and
galactic superluminal sources. Here we propose a simple analytical model of
decelerated motion which is able to explain the shape of double-peaked light
curves of gamma-ray bursts. We show that the differences between individual
bursts of this class may be due to the angle between the line-of-sight and
direction of the outflow, and that the duration of the burst is intimately
connected with the deceleration parameter. Assuming special relativity formulae
and the orientation of the observer with respect to the outflow, we are able to
model observed double-peaked light curves and obtain good quality fits. We
propose that such smooth double peaked bursts could be produced by new born
galactic superluminal sources.


title: Three Binary Millisecond Pulsars in NGC 6266

abstract:
  We present rotational and astrometric parameters of three millisecond pulsars
located near the center of the globular cluster NGC 6266 (M62) resulting from
timing observations with the Parkes radio telescope. Their accelerations toward
the cluster center yield values of the cluster central density and
mass-to-light ratio consistent with those derived from optical data. The three
pulsars are in binary systems. One (spin period P=5.24 ms) is in a 3.5-day
orbit around a companion of minimum mass 0.2 Msun. The other two millisecond
pulsars (P=3.59 ms and 3.81 ms) have shorter orbital periods (3.4 hr and 5.0
hr) and lighter companions (minimum mass 0.12 Msun and 0.07 Msun respectively).
The pulsar in the closest system is the fifth member of an emerging class of
millisecond pulsars displaying irregular radio eclipses and having a relatively
massive companion. This system is a good candidate for optical identification
of the companion star. The lack of known isolated pulsars in NGC 6266 is also
discussed.


title: Sgr A East and its surroundings observed in X-rays

abstract:
  We report the results of an XMM-Newton observation of Sgr A East and its
surroundings. The X-ray spectrum of Sgr A East is well represented with a
two-temperature plasma model with temperatures of ~1 and ~4 keV. Only the iron
abundance shows clear spatial variation; it concentrates in the core of Sgr A
East. The derived plasma parameters suggest that Sgr A East originated in a
single supernova. Around Sgr A East, there is a broad distribution of hard
X-ray emission with a superimposed soft excess component extending away from
the location of Sgr A East both above and below the plane. We discuss the
nature of these structures as well as the close vicinity of Sgr A*.


title:
Short-lived nuclei in the Galaxy and in the early solar system: crucial
  tests expected from gamma-ray line observations

abstract:
  We discuss some open problems in the understanding of the Early Solar System
abundances of short-lived radioactive isotopes, and the important clarification
expected on this matter by precise measurements of the average galactic
abundances of 26Al and 60Fe, through their gamma-ray lines.


title:
Dependences of the X-ray luminosity and pulsar wind nebula on different
  parameters of pulsars and the evolutionary effects

abstract:
  Dependences of the X-ray luminosity (L$_x$) of single pulsars, due to
ejection of relativistic particles, on electric field intensity, rate of
rotational energy loss (\.{E}), magnetic field, period, and the energy spectra
of the ejected particles are discussed. Influence of the magnetic field and
effects of some other parameters of neutron stars on the L$_x$-\.{E} and the
L$_x$-$\tau$ (characteristic time) dependences are considered. Evolutionary
factors also play an important role in our considerations. We find that only
the pulsars with L$_{2-10keV}$$>10^{33}$ erg/s have pulsar wind nebula around
them. The pulsars from which $\gamma$-ray radiation has been observed have low
X-ray luminosities in general.


title: Turbulent Mixing in Clusters of Galaxies

abstract:
  We present a spherically-symmetric, steady-state model of galaxy clusters in
which radiative cooling from the hot gas is balanced by heat transport through
turbulent mixing. We assume that the gas is in hydrostatic equilibrium, and
describe the turbulent heat diffusion by means of a mixing length prescription
with a dimensionless parameter alpha_mix. Models with alpha_mix ~ 0.01-0.03
yield reasonably good fits to the observed density and temperature profiles of
cooling core clusters. Making the strong simplification that alpha_mix is
time-independent and that it is roughly the same in all clusters, the model
reproduces remarkably well the observed scalings of X-ray luminosity, gas mass
fraction and entropy with temperature. The break in the scaling relations at kT
\~ 1-2 keV is explained by the break in the cooling function at around this
temperature, and the entropy floor observed in galaxy groups is reproduced
naturally.


title: Blazars: the next gamma-ray view of GLAST

abstract:
  Blazars, the extreme family of AGN, can be strong gamma-ray emitters and
constitute the largest fraction of identified point sources of EGRET. The next
Gamma-ray Large Area Space Telescope (GLAST) is a high energy (30MeV-300GeV)
gamma-ray astronomy mission, planned for launch at the end of 2006. GLAST
performances will allow to detect few thousands of gamma-ray blazars, with a
broad band coverage and temporal resolution, also in quiescent emission phases,
providing probably many answers about these sources.


title:
Mid-infrared photometry of carbon stars and perspectives for surveys in
  the Magellanic Clouds from Dome-C

abstract:
  A preliminary analysis of the data from the MSX space infrared satellite,
seems to confirm that the [8.8]-[12.5] micron color index is well correlated
with the mass-loss rates in carbon stars of our Galaxy. The extension of this
mid-infrared observation criterion to the Magellanic Clouds, with a small-size
telescope, able to perform a continuous survey from Dome-C on the Antarctic
Plateau, could be crucial to trace the local AGB population and evolution.


title:
Radial distance on a stationary frame in a homogeneous and isotropic
  universe

abstract:
  This paper presents a physical distance to all radial events in a homogeneous
and isotropic universe as a transform from Friedman-Lemaitre-Robertson-Walker
(FLRW) coordinates, the model that solves the Einstein Field equation for an
ideal fluid. Any well behaved transform is also a solution. The problem is
relating the coordinates of the transform to observables. In the present case
the objective is to find T,R on a stationary frame that has the R be a physical
observable for all distances. We do this by working backwards, assuming the
form of the metric that we desire, with some undetermined coefficients. These
coefficients are then related to the partial derivatives of the transform. The
transformed coordinates T,R are found by the integration of partial
differential equations in the FLRW variables. We show that dR has the same
units as the radial differential of the FLRW metric, which makes it observable.
We develop a criterion for how close the transformed T comes to an observable
time. Close to the space origin at the present time, T also becomes physical,
so that the stationary acceleration becomes Newtonian. We show that a galactic
point on a R,T plot starts close to the space origin at the beginning, moves
out to a physical distance and finite time where it can release light that will
be seen at the origin at the present time. Lastly, because the observable R has
a finite limit at a finite T for t = 0 where the galactic velocity approaches
the light speed, we see that the universe filled with an ideal fluid as seen on
clocks and rulers on the stationary frame has a finite extent like that of an
expanding empty universe, beyond which are no galaxies and no space.


title: Meeting the Cool Neighbors VII: Spectroscopy of faint, red NLTT dwarfs

abstract:
  We present low-resolution optical spectroscopy and BVRI photometry of 453
candidate nearby stars drawn from the NLTT proper motion catalogue. The stars
were selected based on optical/near-infrared colours, derived by combining the
NLTT photographic data with photometry from the 2MASS Second Incremental Data
Release. Based on the derived photometric and spectroscopic parallaxes, we
identify 111 stars as lying within 20 parsecs of the Sun, including 9 stars
with formal distance estimates of less than 10 parsecs. A further 53 stars have
distance estimates within 1-sigma of our 20-parsec limit. Almost all of those
stars are additions to the nearby star census. In total, our NLTT-based survey
has so far identified 496 stars likely to be within 20 parsecs, of which 195
are additions to nearby-star catalogues. Most of the newly-identified nearby
stars have spectral types between M4 and M8.


title:
Differential Astrometry of Sub-arcsecond Scale Binaries at the Palomar
  Testbed Interferometer

abstract:
  We have used the Palomar Testbed Interferometer to perform very high
precision differential astrometry on the 0.25 arcsecond separation binary star
HD 171779. In 70 minutes of observation we achieve a measurement uncertainty of
approximately 9 micro-arcseconds in one axis, consistent with theoretical
expectations. Night-to-night repeatability over four nights is at the level of
16 micro-arcseconds. This method of very-narrow-angle astrometry may be
extremely useful for searching for planets with masses as small as 0.5 Jupiter
Masses around a previously neglected class of stars -- so-called ``speckle
binaries.'' It will also provide measurements of stellar parameters such as
masses and distances, useful for constraining stellar models at the 10^-3
level.


title: Wormholes and Ringholes in a Dark-Energy Universe

abstract:
  The effects that the present accelerating expansion of the universe has on
the size and shape of Lorentzian wormholes and ringholes are considered. It is
shown that, quite similarly to how it occurs for inflating wormholes, relative
to the initial embedding-space coordinate system, whereas the shape of the
considered holes is always preserved with time, their size is driven by the
expansion to increase by a factor which is proportional to the scale factor of
the universe. In the case that dark energy is phantom energy, which is not
excluded by present constraints on the dark-energy equation of state, that size
increase with time becomes quite more remarkable, and a rather speculative
scenario is here presented where the big rip can be circumvented by future
advanced civilizations by utilizing sufficiently grown up wormholes and
ringholes as time machines that shortcut the big-rip singularity.


title: A V-Band Survey for Variable Galactic Nuclei in the Hubble Deep Field

abstract:
  We present the results of a 2-epoch variability survey in the Hubble Deep
Field with the goal of investigating the population of AGN to z=1. The primary
data sets analyzed for galactic variability are the original HDF observations
obtained in 1995 and a second V-band image obtained 5 years later in 2000. We
find evidence for nuclear variability in 16 of 217 galaxies brighter than
V_nuc=27.5. Correcting for incompleteness and spurious detections, variable
nuclei make up ~8% of the surveyed galaxies. Seven of our variable sources are
coincident with X-ray sources detected in the 2Ms Chandra survey. We find that
44% of the variable nuclei are associated with mid-IR detections at 15 microns
and 31% are detected at 1.4GHz. Optical spectra are available for 13 of the 16
variables. One is a broad-line AGN and 2 others show weak evidence of type 2
AGNs. With the assumption that these variables are all active nuclei, we
estimate the AGN LF at 0.4<z<1.1 extending to M_B=-15. We find evidence for an
increase in the number density of faint AGN when comparing to the local Seyfert
luminosity function. The LF for optically varying nuclei appears to rise in
number density with no evidence of turning over at these faint magnitudes.


title: Anomalous Evolution of the Dwarf Galaxy HIPASS J1321-31

abstract:
  We present HST/WFPC2 observations of the dwarf galaxy HIPASS J1321-31. This
unusual galaxy lies in the direction of the Centaurus A group of galaxies, and
has a color-magnitude diagram with a distinctive red plume of luminous stars.
This feature could arise from (a) a red giant branch if the galaxy were much
nearer than previously recognized, (b) a peculiar asymptotic giant branch, or,
(c) an ~1 Gigayear old population of intermediate mass red supergiants, which
we find to be the most likely explanation. However, the lack of equally
luminous blue stars requires that the star formation has dropped substantially
since these stars were formed. Evidently HIPASS J1321-31 experienced an episode
of enhanced star formation rather recently in its star formation history
followed by a period of relative quiescence which has led to the evolution of
the main sequence stars into the red supergiant branch. The stellar populations
in HIPASS J1321-31 reflect a star formation history that is uncommon in star
forming dwarf galaxies. This is the first time such a star formation history
has been noted, although the literature contains a small number of other dwarf
galaxies with similar color-magnitude diagrams. Therefore, HIPASS J1321-31 and
these other galaxies represent a different path of dwarf galaxy evolution that
has not been well-explored and an important probe into how dwarf galaxies
evolve.


title: Dark Matter Profile in the Galactic Center

abstract:
  We describe a quasi-equilibrium profile of dark matter particles in the inner
parsec of the Galaxy, rho ~ r^-3/2. This "mini-cusp" profile is caused by
scattering with the dense stellar cluster around the supermassive black hole in
Sgr A* and is independent of the initial conditions. The implications for
detection of gamma rays from WIMP dark matter annihilation in the Galactic
center are a mild enhancement of the flux, and a characteristic central feature
in the angular distribution which could be detectable by high-resolution
Atmospheric Cherenkov Telescopes.


title:
The Internal Ultraviolet-to-Optical Color Dispersion: Quantifying the
  Morphological K-Correction

abstract:
  We present a quantitative measure of the internal color dispersion within
galaxies, which quantifies differences in morphology as a function of
wavelength. We apply this statistic to a local galaxy sample with archival
images at 1500 and 2500 Angstroms from the Ultraviolet Imaging Telescope, and
ground-based B-band observations to investigate how the color dispersion
relates to global galaxy properties. The intenal color dispersion generally
correlates with transformations in galaxy morphology as a function of
wavelength, i.e., it quantifies the morphological K-correction. Mid-type spiral
galaxies exhibit the highest dispersion in their internal colors, which stems
from differences in the bulge, disk, and spiral-arm components. Irregulars and
late-type spirals show moderate internal color dispersion, which implies that
young stars generally dominate the colors. Ellipticals, lenticulars, and
early-type spirals generally have low or negligible internal color dispersion,
which indicates that the stars contributing to the UV-to-optical emission have
a very homogeneous distribution. We discuss the application of the internal
color dispersion to high-redshift galaxies in deep, Hubble Space Telescope
images. By simulating local galaxies at cosmological distances, many of the
galaxies have luminosities that are sufficiently bright at rest--frame optical
wavelengths to be detected within the limits of the currently deepest
near-infrared surveys even with no evolution. Under assumptions that the
luminosity and color evolution of the local galaxies conform with the measured
values of high-redshift objects, we show that galaxies' intrinsic internal
color dispersion remains measurable out to z ~ 3.


title: (Sub-)mm interferometry in massive star-forming regions

abstract:
  (Sub-)mm interferometry is the most favorable technique to investigate the
earliest stages of massive star formation. I will outline general applications
in that field and discuss results of different sub-topics (hot core chemistry
and massive molecular outflows). Furthermore, recent data obtained with the
Submillimeter Array will be shown to present the unique capabilities of this
new instrument. Finally, I will give a short outlook on the main physical
topics of massive star formation to be tackled with (sub-)mm interferometry
within the next decade.


title: Giant Molecular Clouds in M33 - I. BIMA All Disk Survey

abstract:
  We present the first interferometric CO(J=1->0) map of the entire H-alpha
disk of M33. The 13" diameter synthesized beam corresponds to a linear
resolution of 50 pc, sufficient to distinguish individual giant molecular
clouds (GMCs). From these data we generated a catalog of 148 GMCs with an
expectation that no more than 15 of the sources are spurious. The catalog is
complete down to GMC masses of 1.5 X 10^5 M_sun and contains a total mass of
2.3 X 10^7 M_sun. Single dish observations of CO in selected fields imply that
our survey detects ~50% of the CO flux, hence that the total molecular mass of
M33 is 4.5 X 10^7 M_sun, approximately 2% of the HI mass. The GMCs in our
catalog are confined largely to the central region (R < 4 kpc). They show a
remarkable spatial and kinematic correlation with overdense HI filaments; the
geometry suggests that the formation of GMCs follows that of the filaments. The
GMCs exhibit a mass spectrum dN/dM ~ M^(-2.6 +/- 0.3), considerably steeper
than that found in the Milky Way and in the LMC. Combined with the total mass,
this steep function implies that the GMCs in M33 form with a characteristic
mass of 7 X 10^4 M_sun. More than 2/3 of the GMCs have associated HII regions,
implying that the GMCs have a short quiescent period. Our results suggest the
rapid assembly of molecular clouds from atomic gas, with prompt onset of
massive star formation.


title:
The Propagation and Eruption of Relativistic Jets from the Stellar
  Progenitors of GRBs

abstract:
  New two- and three-dimensional calculations are presented of relativistic jet
propagation and break out in massive Wolf-Rayet stars. Such jets are thought
responsible for gamma-ray bursts. As it erupts, the jet is surrounded by a
cocoon of less energetic, but still highly relativistic ejecta that expands and
becomes visible at much larger polar angles. These less energetic ejecta may be
the origin of X-ray flashes and other high-energy transients which will be
visible to a larger fraction of the sky, albeit to a shorter distance than
common gamma-ray bursts. Jet stability is also examined in three-dimensional
calculations. If the jet changes angle by more than three degrees in several
seconds, it will dissipate, producing a broad beam with inadequate Lorentz
factor to make a common gamma-ray burst.


title: The Nature and Origin of the Non-Void Lyman alpha Cloud Population

abstract:
  I continue my study of the low-z Lyman alpha cloud population. Previously I
showed how galaxy catalogs are used to attribute relative degrees of isolation
to those clouds found in HST/GHRS spectra. I find that there exist two distinct
populations corresponding to two distinct environments, variously characterized
as void (unshocked) and non-void (shocked). Void clouds have a steep equivalent
width distribution (i.e., many smaller absorbers) while non-void clouds have a
flat distribution. These environment-specific observations of LyA clouds show
that the predictions from N-body/hydro simulations are incorrect. Simulations
fail to predict the existence of significant numbers of detectable void clouds.
They incorrectly predict the characteristics of non-void clouds. Implicated in
this failure is the so-called fluctuating Gunn-Peterson Approximation (FGPA)
which envisions that LyA absorbers are formed in the large-scale structures of
coalescing matter. I recently modeled the void cloud population as sub-galactic
perturbations that have expanded in response to reionization. However, the
success in this modeling was contingent upon using the more massive isothermal
halo in place of the standard Navarro, Frenk & White. Here, I extend my
modeling to non-void LyA clouds using the same basic cloud model. Nonvoid
clouds were once unshocked, but when entering nonvoid space, they are shock
stripped. By analytically stripping model void clouds, a good fit of the model
CDS to observations is found if cloud velocities are ~100 km/s. Nonvoid clouds
show strong concentration around galaxies, suggesting that the compact HVC
population are members of this population.


title:
Where is a Marginally Stable Last Circular Orbit in Super-Critical
  Accretion Flow?

abstract:
  Impressed by the widespread misunderstanding of the issue, we return to the
old question of the location of the inner edge of accretion disk around black
hole. We recall the fundamental results obtained in the 1970's and 1980's by
Warsaw and Kyoto research groups that proved, in particular, that the inner
edge does not coincide with the location of the innermost stable Keplerian
circular orbit. We give some novel illustrations of this particular point and
of some other fundamental results obtained by Warsaw and Kyoto groups. To
investigate the flow dynamics of the inner edge of accretion disk, we carefully
solve the structure of the transonic flow and plot the effective potential
profile based on the angular-momentum distribution calculated numerically. We
show that the flow does not have a potential minimum for accretion rates, {\dot
M} > 10 L_E/c^2 (with L_E being the Eddington luminosity and
  $c$ being the speed of light). This property is realized even in relatively
small viscosity parameters
  (i.e., \alpha ~ 0.01), because of the effect of pressure gradient. In
conclusion, the argument based on the last circular orbit of a test particle
cannot give a correct inner boundary of the super-critical flow and the inner
edge should be determined in connection with radiation efficiency. The same
argument can apply to optically thin ADAF. The interpretation of the observed
QPO frequencies should be re-considered, since the assumption of Kepler
rotation velocity can grossly over- or underestimate the disk rotation
velocity, depending on the magnitude of viscosity.


title:
The Lateral Distribution Function of Shower Signals in the Surface
  Detector of the Pierre Auger Observatory

abstract:
  The surface detector (SD) array of the southern Pierre Auger Observatory will
consist of a triangular grid of 1600 water Cherenkov tanks with 1.5 km spacing.
For zenith angles less than 60deg the primary energy can be estimated from the
signal S(1000) at a distance of about 1000m from the shower axis, solely on
basis of SD data. A suitable lateral distribution function (LDF) S(r) is fitted
to the signals recorded by the water tanks and used to quantify S(1000).
Therefore, knowledge of the LDF is a fundamental requirement for determining
the energy of the primary particle. The Engineering Array (EA), a prototype
facility consisting of 32 tanks, has taken data continuously since late 2001.
On the basis of selected experimental data and Monte Carlo simulations various
preliminary LDFs are examined.


title: On the importance of inner-shell transitions for opacity calculations

abstract:
  For high temperatures and densities, stellar opacities obtained from the
Opacity Project (OP) were smaller than those obtained from the OPAL project.
Iglesias and Rogers [Ap.J. v443, 469 (1995)] suggested that the discrepancy was
due to the omission by OP of important atomic inner-shell processes, and
considered in detail results for a mixture of 6 elements: H, He, C, O, S and
Fe. Extensive new inner-shell data have now been computed using the code
AUTOSTRUCTURE. It is shown that the inclusion of these data in the OP work
gives opacities for the 6-element mix which are in much closer agreement with
those from OPAL. We also discuss a number of problems relating to the
calculation of opacities and of equations-of-state in dense plasmas.


title: A spatially resolved limb flare on Algol B observed with XMM-Newton

abstract:
  We report XMM-Newton observations of the eclipsing binary Algol A (B8V) and B
(K2III). The XMM-Newton data cover the phase interval 0.35 - 0.58, i.e.,
specifically the time of optical secondary minimum, when the X-ray dark B-type
star occults a major fraction of the X-ray bright K-type star. During the
eclipse a flare was observed with complete light curve coverage. The decay part
of the flare can be well described with an exponential decay law allowing a
rectification of the light curve and a reconstruction of the flaring plasma
region. The flare occurred near the limb of Algol B at a height of about 0.1R
with plasma densities of a few times 10^11 cm^-3 consistent with spectroscopic
density estimates. No eclipse of the quiescent X-ray emission is observed
leading us to the conclusion that the overall coronal filling factor of Algol B
is small.


title: First INTEGRAL observations of Cygnus X-3

abstract:
  We present the first INTEGRAL results on Cyg X-3 from the PV phase
observations of the Cygnus region. The source was clearly detected by the
JEM-X, ISGRI and SPI detectors. The INTEGRAL observations were supported by
simultaneous pointed RXTE observations. Their lightcurves folded over the 4.8
hour binary period are compatible with the mean RXTE/ASM and CGRO/BATSE light
curves. We fit our broad band X-ray/Gamma-ray spectra with a physical model,
which represents the first such published model for Cyg X-3. The main physical
processes in the source are thermal Comptonization and Compton reflection with
parameters similar to those found for black-hole binaries at high Eddington
rates.


title: A numerical scheme for multifluid magnetohydrodynamics

abstract:
  This paper describes a numerical scheme for multi-fluid hydrodynamics in the
limit of small mass densities of the charged particles. The inertia of the
charged particles can then be neglected, which makes it possible to write an
evolution equation for the magnetic field that can be solved using an implicit
scheme. This avoids the severe restriction on the stable timestep that would
otherwise arise at high resolution, or when the Hall effect is large. Numerical
tests show that the scheme can accurately model steady multi-fluid shock
structures both with and without sub-shocks. Although the emphasis is on shocks
in molecular clouds, a multi-dimensional version of this code could be applied
to any Astrophysical flow in which ambi-polar diffusion or the Hall effect, or
both play a significant role.


title:
New aperture photometry of QSO 0957+561; application to time delay and
  microlensing

abstract:
  We present a re-reduction of archival CCD frames of the doubly imaged quasar
0957+561 using a new photometry code. Aperture photometry with corrections for
both cross contamination between the quasar images and galaxy contamination is
performed on about 2650 R-band images from a five year period (1992-1997). From
the brightness data a time delay of 424.9 +/- 1.2 days is derived using two
different statistical techniques. The amount of gravitational microlensing in
the quasar light curves is briefly investigated, and we find unambiguous
evidence of both long term and short term microlensing. We also note the
unusual circumstance regarding time delay estimates for this gravitational
lens. Estimates by different observers from different data sets or even with
the same data sets give lag estimates differing by typically 8 days, and error
bars of only a day or two. This probably indicates several complexities where
the result of each estimate depends upon the details of the calculation.


title: Five nights of intensive R- and V-band photometry of QSO 0957+561A,B

abstract:
  We present R- and V-band photometry of the gravitational lens system QSO
0957+561 from five nights (one in 2000 January and four in 2001 March,
corresponding to the approximate time-delay for the system) of uninterrupted
monitoring at the Nordic Optical Telescope. In the photometry scheme we have
stressed careful magnitude calibration as well as corrections for the lens
galaxy contamination and the crosstalk between the twin (A and B) quasar
images. The resulting, very densely sampled light curves are quite stable, in
conflict with earlier claims derived from the same data material. We estimate
high-precision timelag-corrected B/A flux ratios in both colour bands, as well
as V-R colour indices for A and B, and discuss the short time-scale variability
of the system.


title:
Asymmetries Observed In Giant Air Showers Using Water Cherenkov
  Detectors

abstract:
  Evidence of azimuthal asymmetries in the time structure and signal size has
been found in non-vertical showers as a function of zenith angle. These
asymmetries arise because of the different paths traveled by particles in the
upper and lower sides of the plane perpendicular to the shower axis to reach
detectors at the same axial distances. The shower particles are differentially
attenuated as they traverse the atmosphere. Furthermore, most particles are not
propagating strictly in the shower direction but are on average going away from
the axis. This geometrical projection effect also contributes to the final
asymmetry. These novel observations must be understood for parameterisation of
the lateral distribution function. Additionally, the asymmetry in time
distributions offers a new possibility for the determination of the mass
composition because its magnitude is strongly dependent on the fraction of
electromagnetic signal at the observation level. The asymmetries found in data
collected from the Engineering Array of the Auger Observatory will be compared
with Monte Carlo data.


title:
Processing of the Signals from the Surface Detectors of the Pierre Auger
  Observatory

abstract:
  The detectors of the surface array of the Pierre Auger Observatory are water
Cherenkov tanks. The signals from each tank are read out using three
photomultipliers. The energy of the primary particle is inferred from signal
densities and requires good linearity of the PMTs and a large dynamic range.
The absolute time of arrival of the shower front at each tank is obtained from
the Global Positioning System (GPS) with a resolution of about 10 ns, ensuring
an accurate primary angular reconstruction. Additionally, it is intended to use
the rise time and shape of the signals to constrain the nature of the primary
particle: this sets further requirements on the signal processing. In this
paper, the main features of the signal processing associated with the surface
detector will be presented and its performance will be discussed in the context
of the extraction of shower parameters.


title:
CENSORS: A Combined EIS-NVSS Survey Of Radio Sources. I. Sample
  definition, radio data and optical identifications

abstract:
  A new sample of radio sources, with the designated name CENSORS (A Combined
EIS-NVSS Survey Of Radio Sources), has been defined by combining the NRAO VLA
Sky Survey (NVSS) at 1.4 GHz with the ESO Imaging Survey (EIS) Patch D, a 3 by
2 degree region of sky centred at 09 51 36.0, -21 00 00 (J2000). New radio
observations of 199 NVSS radio sources with NVSS flux densities S(1.4GHz) >
7.8mJy are presented, and compared with the EIS I-band imaging observations
which reach a depth of I~23; optical identifications are obtained for over
two-thirds of the ~150 confirmed radio sources within the EIS field. The radio
sources have a median linear size of 6 arcseconds, consistent with the trend
for lower flux density radio sources to be less extended. Other radio source
properties, such as the lobe flux density ratios, are consistent with those of
brighter radio source samples. From the optical information, 30-40% of the
sources are expected to lie at redshifts z >~ 1.5.
  One of the key goals of this survey is to accurately determine the high
redshift evolution of the radio luminosity function. These radio sources are at
the ideal flux density level to achieve this goal; at redshifts z~2 they have
luminosities which are around the break of the luminosity function and so
provide a much more accurate census of the radio source population at those
redshifts than the existing studies of extreme, high radio power sources. Other
survey goals include investigating the dual--population unification schemes for
radio sources, studying the radio luminosity dependence of the evolution of
radio source environments, and understanding the radio power dependence of the
K-z relation for radio galaxies.


title: Intermediate-Mass Black Holes

abstract:
  The mathematical simplicity of black holes, combined with their links to some
of the most energetic events in the universe, means that black holes are key
objects for fundamental physics and astrophysics. Until recently, it was
generally believed that black holes in nature appear in two broad mass ranges:
stellar-mass (roughly 3-20 solar masses), which are produced by the core
collapse of massive stars, and supermassive (millions to billions of solar
masses), which are found in the centers of galaxies and are produced by a still
uncertain combination of processes. In the last few years, however, evidence
has accumulated for an intermediate-mass class of black holes, with hundreds to
thousands of solar masses. If such objects exist they have important
implications for the dynamics of stellar clusters, the formation of
supermassive black holes, and the production and detection of gravitational
waves. We review the evidence for intermediate-mass black holes and discuss
future observational and theoretical work that will help clarify numerous
outstanding questions about these objects.


title:
Synchrotron Radiation from the Crab Nebula Discriminates between Models
  of Space-Time Foam

abstract:
  It has been argued by Jacobson, Liberati and Mattingly that synchrotron
radiation from the Crab Nebula imposes a stringent constraint on any
modification of the dispersion relations of the electron that might be induced
by quantum gravity. We supplement their analysis by deriving the spectrum of
synchrotron radiation from the coupling of an electrically-charged particle to
an external magnetic fields in the presence of quantum-gravity effects of the
general form $(E/M_{QG})^\alpha$. We find that the synchrotron constraint from
the Crab Nebula practically excludes $\alpha \lsim 1.74$ for $M_{QG} \sim m_P =
1.2 \times 10^{19}$ GeV. On the other hand, this analysis does not constrain
any modification of the dispersion relation of the photon that might be induced
by quantum gravity. We point out that such quantum-gravity effects need not
obey the equivalence principle, a point exemplified by the Liouville-string
D-particle model of space-time foam. This model suggests a linear modification
of the dispersion relation for the photon, but not for the electron, and hence
is compatible with known constraints from the Crab Nebula and elsewhere.


title: Probing Dark Energy in the Accelerating Universe with SNAP

abstract:
  It has now been firmly established that the Universe is expanding at an
accelerated rate, driven by a presently unknown form of dark energy that
appears to dominate our Universe today. A dedicated satellite mission has been
designed to precisely map out the cosmological expansion history of the
Universe and thereby determine the properties of the dark energy. The
SuperNova/Acceleration Probe (SNAP) will study thousands of distant supernovae,
each with unprecedented precision, using a 2-meter aperture telescope with a
wide field, large-area optical-to-near-IR imager and high-throughput
spectrograph. SNAP can not only determine the amount of dark energy with high
precision, but test the nature of the dark energy by examining how its equation
of state evolves. The images produced by SNAP will have an unprecedented
combination of depth, solid-angle, angular resolution, and temporal sampling
and will provide a rich program of auxiliary science.


title:
HIDEEP - An extragalactic blind survey for very low column-density
  neutral hydrogen

abstract:
  We have carried out an extremely long integration-time (9000 s/beam) 21-cm
blind survey of 60 square degrees in Centaurus using the Parkes multibeam
system. We find that the noise continues to fall as sqrt(t) throughout,
enabling us to reach an HI column-density limit of 4.2 x 10^18 cm^-2 for
galaxies with a velocity width of 200 km/s in the central 32 square degree
region, making this the deepest survey to date in terms of column density
sensitivity. The HI data are complemented by very deep optical observations
from digital stacking of multi-exposure UK Schmidt Telescope R-band films,
which reach an isophotal level of 26.5 R mag arcsec^-2 (~27.5 B mag arcsec^-2).
173 HI sources have been found, 96 of which have been uniquely identified with
optical counterparts in the overlap area. There is not a single source without
an optical counterpart. Although we have not measured the column-densities
directly, we have inferred them from the optical sizes of their counterparts.
All appear to have a column-density of N_HI = 10^(20.65 +/- 0.38). This is at
least an order of magnitude above our sensitivity limit, with a scatter only
marginally larger than the errors on N_HI. This needs explaining. If confirmed
it means that HI surveys will only find low surface brightness (LSB) galaxies
with high M_HI/L_B. Gas-rich LSB galaxies with lower HI mass to light ratios do
not exist. The paucity of low column-density galaxies also implies that no
significant population will be missed by the all-sky HI surveys being carried
out at Parkes and Jodrell Bank.


title: Type I Planetary Migration with MHD Turbulence

abstract:
  This paper examines how type I planet migration is affected by the presence
of turbulent density fluctuations in the circumstellar disk. For type I
migration, the planet does not clear a gap in the disk and its secular motion
is driven by torques generated by the wakes it creates in the surrounding disk
fluid. MHD turbulence creates additional density perturbations that
gravitationally interact with the planet and can dominate the torques produced
by the migration mechanism itself. This paper shows that conventional type I
migration can be readily overwhelmed by turbulent perturbations and hence the
usual description of type I migration should be modified in locations where the
magnetorotational instability is active. In general, the migrating planet does
not follow a smooth inward trned, but rather exhibits a random walk through
phase space. Our main conclusion is that MHD turbulence will alter the time
scales for type I planet migration and -- because of chaos -- requires the time
scales to be described by a distribution of values.


title: First Star Signature in Infrared Background Anisotropies

abstract:
  (Abridged) Recent cosmic microwave background anisotropy results from the
Wilkinson Microwave Anisotropy Probe suggest that the universe was reionized at
a redshift around 20. Such an early reionization could arise through the
ionizing radiation emitted by metal-free population III stars at redshifts of
10 and higher. We discuss infrared background (IRB) surface brightness spatial
fluctuations from such a generation of early star formation. We show that the
spatial clustering of these stars at tens of arcminute scales generates a
contribution to the angular power spectrum of the IRB anisotropies at the same
angular scales. This excess can be potentially detected when resolved
foreground galaxies out to a redshift of a few is removed from the clustering
analysis. Additionally, assuming a population III stellar spectrum, we suggest
that the clustering excess related to the first generation of stars can be
separated from brightness fluctuations resulting from other foreground sources
and galaxies using multifrequency observations in the wavelength range of ~ 1
to 5 microns. In addition to removing the low-redshift galaxy population, the
multifrequency data are essential to account for certain foreground
contaminants such zodiacal light, which, if varying spatially over degree
scales, can be a significant source of confusion for the proposed study. Using
various instruments, we study the extent to which spatial fluctuations of the
IRB can be studied in the near future.


title: Lower Mass Black Holes in the GOODS? Off-nuclear X-ray Sources

abstract:
  We have identified a sample of 10 highly reliable off-nuclear (> 2 kpc) X-ray
sources at z=0.03-0.25 in late-type host galaxies within the two GOODS fields
(i.e., the two Chandra Deep Fields). The combination of the superb spatial
resolution and great depth of the HST ACS and Chandra ACIS coverage in the
GOODS fields is critical to the identification of these sources. We extend the
study of this enigmatic population up to higher redshifts and larger look-back
times than has been possible before, finding that the fraction of optically
luminous galaxies exhibiting luminous off-nuclear sources at z~0.1 is larger
than at the current time (~36% versus ~8%). The X-ray luminosities of the GOODS
off-nuclear X-ray sources are comparable to or slightly greater than the
integrated point-source X-ray luminosities of nearby galaxies, providing a
possible constraint on the X-ray Luminosity Function at higher star-formation
rates. X-ray variability demonstrates that several of these sources are likely
single accreting black holes; for the majority, however, the number of X-ray
counts is too low for X-ray variability studies.


title:
A Characteristic Dense Environment or Wind Signature in Prompt GRB
  Afterglows

abstract:
  We discuss the effects of synchrotron self-absorption in the prompt emission
from the reverse shock of GRB afterglows occurring in a dense environment, such
as the wind of a massive stellar progenitor or a dense ISM in early galaxies.
We point out that, when synchrotron losses dominate over inverse Compton
losses, the higher self-absorption frequency in a dense environment implies a
bump in the reverse shock emission spectrum, which can result in a more complex
optical/IR light curve than previously thought. This bump is prominent
especially if the burst ejecta is highly magnetized. In the opposite case of
low magnetization, inverse Compton losses lead to a prompt X-ray flare. These
effects give a possible new diagnostic for the magnetic energy density in the
fireball, and for the presence of a dense environment.


title: Calibration of the Pierre Auger fluorescence detector

abstract:
  The absolute calibration of an air fluorescence detector (FD) is an important
element in correctly determining the energy of detected cosmic rays. The
absolute calibration relates the flux of photons of a given wavelength at the
detector aperture to the electronic signal recorded by the FD data acquisition
system. For the Auger FDs, the primary absolute calibration method uses a
diffusive surface which is placed in front of a telescope aperture to uniformly
illuminate the telescope field of view with a known light signal. This
single-wavelength measurement (375 nm) will be made at intervals of several
months until the stability of the telescopes is determined. The relative
wavelength dependence of the calibration is determined through independent
measurements. The error in absolute calibration at a single wavelength is
estimated to be less than 10%. Two other absolute calibration methods are used
to provide an independent verification of the primary measurement. The
stability of the calibration with time is monitored nightly by a relative
calibration system. In this paper we will provide descriptions of the absolute
and relative calibration methods used by the Auger air fluorescence
observatory. Results from the calibration of the Auger Engineering Array
telescopes will also be presented.


title: The Most Distant Galaxies

abstract:
  I review selected current observations of distant galaxies and our
interpretation of the fragile (and occasionally contradictory) data. Galaxies
at the ``contemporary limit'' of technology and redshift (z~6) are difficult to
locate in the first place. Moreover, the large redshift may push some critical
confirming and/or interpretative analysis toward unfamiliar IR wavelengths. I
will concentrate on observational means and results to explore the early
evolution of galaxies. We also note the biases that intrude on plans for the
interpretative aspects of distant galaxy photometry and spectroscopy. We
discuss the best methods of selection for those very distant systems; these
methods include utilizing strong sub-mm emission from dust, photometry
indicating a UV "spectral break," and finally the signal of a strong Lyman
alpha emission line. This feature has now carried us to a galaxy redshift in
excess of z = 6.57!


title: Polarization and kinematics in Cygnus A

abstract:
  From optical spectropolarimetry of Cygnus A we conclude that the scattering
medium in the ionization cones in Cygnus A is moving outward at a speed of
170+-34 km/s, and that the required momentum can be supplied by the radiation
pressure of an average quasar. Such a process could produce a structure
resembling the observed ionization cones, which are thought to result from
shadowing by a circumnuclear dust torus. We detect a polarized red wing in the
[O III] emission lines arising from the central kiloparsec of Cygnus A. This
wing is consistent with line emission created close to the boundary of the
broad-line region.


title: A new upper limit on the reflected starlight from Tau Bootis b

abstract:
  Using improved doppler tomographic signal-analysis techniques we have carried
out a deep search for starlight reflected from the giant planet orbiting the
star Tau Bootis. We combined echelle spectra secured at the 4.2 m William
Herschel telescope in 1998 and 1999 (which yielded a tentative detection of a
reflected starlight component from the orbiting companion) with new data
obtained in 2000 (which failed to confirm the detection). The combined dataset
comprises 893 high resolution spectra with a total integration time of 75 hr 32
min spanning 17 nights. We establish an upper limit on the planet's geometric
albedo p<0.39 (at the 99.9 % significance level) at the most probable orbital
inclination i=36 degrees, assuming a grey albedo, a Venus-like phase function
and a planetary radius R_p=1.2 R_Jup. We are able to rule out some combinations
of the predicted planetary radius and atmospheric albedo models with high,
reflective cloud decks. Although a weak candidate signal appears near to the
most probable radial velocity amplitude, its statistical significance is
insufficient for us to claim a detection with any confidence.


title: Prospects for Spectroscopic Reflected-light Planet Searches

abstract:
  High-resolution spectroscopic searches for the starlight reflected from
close-in extra-solar giant planets have the capability of determining the
optical albedo spectra and scattering properties of these objects. When
combined with radial velocity measurements they also yield the true mass of the
planet. To date, only two such planets have been targeted for reflected-light
signals, yielding upper limits on the planets' optical albedos. Here we examine
the prospects for future searches of this kind. We present Monte Carlo
estimates of prior probability distributions for the orbital velocity
amplitudes and planet/star flux ratios of 6 bright stars known to harbour giant
planets in orbits with periods of less than 5 days. Using these estimates, we
assess the viability of these targets for future reflected-light searches using
4m and 8m-class telescopes.


title:
Gravitational Binding, Virialization and the Peculiar Velocity
  Distribution of the Galaxies

abstract:
  We examine the peculiar velocity distribution function of galaxies in
cosmological many-body gravitational clustering. Our statistical mechanical
approach derives a previous basic assumption and generalizes earlier results to
galaxies with haloes. Comparison with the observed peculiar velocity
distributions indicates that individual massive galaxies are usually surrounded
by their own haloes, rather than being embedded in common haloes. We then
derive the density of energy states, giving the probability that a randomly
chosen configuration of N galaxies in space is bound and virialized.
Gravitational clustering is very efficient. The results agree well with the
observed probabilities for finding nearby groups containing N galaxies. A
consequence is that our local relatively low mass group is quite typical, and
the observed small departures from the local Hubble flow beyond our group are
highly probable.


title: Using Globular Clusters to Test Newton?s Law of Gravityy

abstract:
  New measurements of the velocity dispersion of the globular cluster omega
Centauri allow to trace its gravitational potential down to an acceleration of
8e-9 cm/s/s. It is found that the dispersion profile remains flat well inside
the tidal radius as soon as the acceleration of gravity approaches a_0, a
result that finds its simplest explanation within the contest of Modified
Newtonian dynamics. A similar behavior is observed in the globular cluster M15
showing this is not a peculiar features of omega Centauri. This result is
surprising and suggestive of a failure of Newton's law at low accelerations.


title: The Case for Asymmetric Dust Around a C-Rich AGB star

abstract:
  JHKL observations of the mass-losing carbon Mira variable IRAS 15194-5115 (II
Lup) extending over about 18 years are presented and discussed. The pulsation
period is 575 days and has remained essentially constant over this time span.
The star has undergone an extensive obscuration minimum during this time. This
is complex and, like such minima in similar objects, e.g. R For, does not fit
the model predictions of a simple long term periodicity. Together with the high
resolution observations of Lopez et al. the results suggest that the
obscuration changes are due to the formation of dust clouds of limited extent
in the line-of-sight. This is an RCB-type model. The effective reddening law at
J and H is similar to that found for R For.


title: Measuring and Understanding the Universe

abstract:
  Revolutionary advances in both theory and technology have launched cosmology
into its most exciting period of discovery yet. Unanticipated components of the
universe have been identified, promising ideas for understanding the basic
features of the universe are being tested, and deep connections between physics
on the smallest scales and on the largest scales are being revealed.


title:
The Lame$^{\prime}$ Equation for Distance-Redshift in Partially Filled
  Beam Friedmann-Lema\^\i tre-Robertson-Walker Cosmology

abstract:
  The differential equation governing distance-redshift for partially
filled-beam optics in pressure-freeFriedmann-Lema\^\i tre-Robertson-Walker
Cosmology (FLRW) is shown to be the Lame$^{\prime}$ equation. The
distance-redshift, $D(z)$, discussed is appropriate for observations in
inhomogeneous cosmologies for which lensing by masses external to the observing
beam are negligible and for which lensing by transparent matter within the beam
can be approximated by a homogeneous mass density expanding with the FLRW
background. Some solutions of the derived Lame$^{\prime}$ equation are given in
terms of Weierstrass elliptic integrals. A new simplified and useful expression
for filled-beam $D(z)$ in standard flat FLRW is also given.


title: Near-Infrared Observations of BL Lacertae Host Galaxies

abstract:
  Multi-band near-infrared images of twelve BL Lacertae objects were obtained
with the 2.5m telescope at the Las Campanas Observatory in order to determine
the properties of their underlying host galaxies. Resolved emission was clearly
detected in eight of the lowest redshift targets (up to z~0.3), and was modeled
with a de Vaucouleurs r^{1/4} surface brightness law. We find that the
morphologies match the elliptical galaxy profiles well, and that the BL Lac
objects reside in large and luminous, but otherwise normal hosts -- consistent
with previous studies done predominantly at optical wavelengths. The median
absolute K-band magnitude of the galaxies in this study is -26.2, the average
half-light radius is 4.2 +/- 2.3 kpc, and their average integrated R-K color is
2.7 +/- 0.3 mag. These are well within the range of values measured previously
in the H-band by Kotilainen et al. and Scarpa et al. in a comparable number of
targets. Taking their data together with our results, we find a best-fit K-band
Kormendy relation of \mu_{e} = 4.3 log_{10} (r_{e}/kpc) + 14.2 mag arcsec^{-2},
virtually identical to that obtained for normal ellipticals. Finally, the
near-infrared colors determined for five galaxies (average J-K = 0.8 +/- 0.3
mag) are the first such measurements for BL Lac hosts, and match those expected
from old stellar populations at the BL Lac redshifts.


title: Dynamics of Relativistic Flows

abstract:
  Dynamics of relativistic outflows along the rotation axis of a Kerr black
hole is investigated using a simple model that takes into account the
relativistic tidal force of the central source as well as the Lorentz force due
to the large-scale electromagnetic field which is assumed to be present in the
ambient medium. The evolution of the speed of the flow relative to the ambient
medium is studied. In the force-free case, the resulting equation of motion
predicts rapid deceleration of the initial flow and an asymptotic relative
speed with a Lorentz factor of 2^1/2. In the presence of the Lorentz force, the
long-term relative speed of the clump tends to the ambient electrical drift
speed.


title:
On the X-ray Image of The Crab Nebula: Comparison with Chandra
  Observations

abstract:
  An axisymmetric model for the Crab Nebula is constructed to examine the flow
dynamics in the nebula. The model is based on that of Kennel and Coroniti
(1984), although we assume that the kinetic-energy-dominant wind is confined in
an equatorial region. The evolution of the distribution function of the
electron-positron plasma flowing out in the nebula is calculated. Given viewing
angles, we reproduce an image of the nebula and compare it with Chandra
observation.
  The reproduced image is not a ring-like but rather 'lip-shaped'. It is found
that the assumption of toroidal field does not reproduce the Chandra image. We
must assume that there is disordered magnetic field with an amplitude as large
as the mean toroidal field. In addition, the brightness contrast between the
front and back sides of the ring cannot be reproduced if we assume that the
magnetization parameter $\sigma$ is as small as $\sim 10^{-3}$. The brightness
profile along the semi-major axis of the torus is also examined. The
non-dissipative, ideal-MHD approximation in the nebula appears to break down.
We speculate that if the magnetic energy is released by some process that
produce turbulent field in the nebula flow and causes heating and acceleration,
e.g. by magnetic reconnection, then the present difficulties may be resolved
(i.e. we can reproduce a ring image, and a higher brightness contrast). Thus,
the magnetization parameter $\sigma$ can be larger than previously expected.


title:
Novel Photon-Counting Detector for 0.1-100 keV X-ray Imaging Possessing
  High Spatial Resolution

abstract:
  We report on a new photon-counting detector possessing unprecedented spatial
resolution, moderate spectral resolution and high background-rejection
capability for 0.1-100 keV X-rays. It consists of an X-ray charge-coupled
device (CCD) and scintillator. The scintillator is directly deposited on the
back surface of the X-ray CCD. Low-energy X-rays below 10 keV can be directly
detected in the CCD. The majority of hard X-rays above 10 keV pass through the
CCD but can be detected in the scintillator, generating optical photons there.
Since CCDs have a moderate detection efficiency for optical photons, they can
again be absorbed by the CCD. We demonstrate the high spatial resolution of 10
micron order for 17.4 keV X-rays with our prototype device.


title:
Erratum: "Oscillations in Arcturus from WIRE photometry" (ApJ, 591, L151
  [2003])

abstract:
  The value of the mode lifetime given in the first paragraph of the Discussion
should be divided by 2pi and is therefore 2.0 days rather than 13 days.


title: Computation of the spectra of the quasars

abstract:
  The repartition of redshifts of the lines observed in the spectra of the
quasars is generally considered as stochastic, but several authors showed that
the difference of two redshifts is the product of an integer by a basic
redshift zf = 0.062. This property results from a coherent Raman effect during
the propagation of the incoherent light in a halo of atomic hydrogen, without
any jet of gas, or dark matter. The coherence forbids a blur of the images or
of the spectra. The computation of zf does not require any new spectroscopic
parameter. The non-linearity of the combination of Lyman absorptions and
coherent Raman effect explains both the observed positions of the spectral
lines and their high contrast.


title: Near-IR coronagraphic imaging of the companion to HR 7672

abstract:
  This article presents coronagraphic images of the low-mass companion to the
star HR 7672 observed at the Palomar 200 inch telescope and first detected at
Gemini and Keck in the K band by \citet{liu02}. We obtained additional
photometry in $J$($1.2\mu m$), $H$($1.6\mu m$) and $K_s$ ($2.2\mu m$) bands to
cover the full near-IR domain and hence to further constrain the nature of the
companion. A mass estimate of 58-71$ \mathrm{M_J}$ is derived from evolutionary
models of very low-mass objects.


title:
Performance of the Pierre Auger Fluorescence Detector and Analysis of
  well recontructed events

abstract:
  The Pierre Auger Observatory is designed to elucidate the origin and nature
of Ultra High Energy Cosmic Rays using a hybrid detection technique. A first
run of data taking with a prototype version of both detectors (the so called
Engineering Array) took place in 2001-2002, allowing the Collaboration to
evaluate the performance of the two detector systems and to approach an
analysis strategy. In this contribution, after a brief description of the
system, we will report some results on the behavior of the Fluorescence
Detector (FD) Prototype. Performance studies, such as measurements of noise,
sensitivity and duty cycle, will be presented. We will illustrate a preliminary
analysis of selected air showers. This analysis is performed using exclusively
the information from the FD, and includes reconstruction of the shower geometry
and of the longitudinal profile


title:
Shower Studies at around 10^18 eV with the Surface Detector of the
  Pierre Auger Observatory

abstract:
  Three months of data taken by the Engineering Array Surface Detector of the
Pierre Auger Observatory have been analyzed with the aim of setting a procedure
for the study of showers at E_0 ~ 10^18 eV. We present the results, concerning:
(i) the selection procedure and the check of its efficiency; (ii) the event
rate and its stability; (iii) the characteristics of such events (i.e., angular
direction, energy estimator S(1000), rise time vs core distance, correlation
with pressure) showing their consistency with the expectations. The
performances of the whole Surface Detector of the Auger Observatory are
discussed.


title:
High precision effective temperatures for 181 F--K dwarfs from
  line-depth ratios

abstract:
  Line depth ratios measured on high resolution (R=42000), high S/N echelle
spectra are used for the determination of precise effective temperatures of 181
F,G,K Main Sequence stars with about solar metallicity (-0.5 < [Fe/H] < +0.5).
A set of 105 relations is obtained which rely Teff on ratios of the strengths
of lines with high and low excitation potentials, calibrated against previously
published precise (1%) temperature estimates. The application range of the
calibrations is 4000--6150 K (F8V--K7V). The internal error of a single
calibration is less than 100 K, while the combination of all calibrations for a
spectrum of S/N=100 reduces uncertainty to only 5-10 K, and for S/N=200 or
higher, to better than 5 K. The zero point of the temperature scale is directly
defined from reflection spectra of the Sun with an uncertainty about 1 K. The
application of this method to investigation of the planet host stars properties
is discussed.


title: The Line Emission Region in III Zw 2: Kinematics and Variability

abstract:
  We have studied the Ly-al, Hbeta, Halpha and Mg II2798 line profiles of the
Seyfert 1 galaxy III Zw 2. The shapes of these broad emission lines show
evidence of a multicomponent origin and also features which may be identified
as the peaks due to a rotating disk. We have proposed a two-component Broad
Line Region (BLR) model consisting of an inner Keplerian relativistic disk and
an outer structure surrounding the disk. The results of the fitting of the four
Broad Emission Lines (BELs) here considered, are highly consistent in both the
inner and outer component parameters. Adopting a mass of approx. 2 E8 sollar
masses for the central object we found that the outer radius of the disk is
approximately equal for the four considered lines (approx 0.01 pc). However,
the inner radius of the disk is not the same: 0.0018 pc for Ly-alpha, 0.0027 pc
for Mg II, and 0.0038 pc for the Balmer lines. This as well as the relatively
broad component present in the blue wings of the narrow [OIII] lines indicate
stratification in the emission-line region. Using long-term Hbeta observations
(1972-1990, 1998) we found a flux variation of the BEL with respect to the
[OIII] lines.


title: The Red Giant Branch Luminosity Function Bump

abstract:
  We present observational estimates of the magnitude difference between the
luminosity function RGB bump and the HB (Delta(bump-zahb)), and of star counts
in the bump region (R_bump), for a sample of 54 Galactic globular clusters
(GCs) observed by the HST. The large sample of stars resolved in each cluster,
and the high photometric accuracy of the data allowed us to detect the bump
also in a number of metal poor clusters. To reduce the photometric
uncertainties, empirical values are compared with theoretical predictions
obtained from a set of updated canonical stellar evolution models which have
been transformed directly into the HST flight system. We found an overall
qualitative agreement between theory and observations. Quantitative estimates
of the confidence level are hampered by current uncertainties on the GCs
metallicity scale, and by the strong dependence of Delta(bump-zahb) on the
cluster metallicity. In case of the R_bump parameter, which is only weakly
affected by the metallicity, we find a very good quantitative agreement between
theoretical canonical models and observations. For our full cluster sample the
average difference between predicted and observed R_bump values is practically
negligible, and ranges from -0.002 to -0.028, depending on the employed
metallicity scale. The observed dispersion around these values is entirely
consistent with the observational errors on R_bump. As a comparison, the value
of R_bump predicted by theory in case of spurious bump detections would be
\~0.10 smaller than the observed ones. We have also tested the influence on the
predicted Delta(bump-zahb) and R_bump values of an He-enriched component in the
cluster stellar population. We find that the predicted Delta(bump-zahb) and
R_bump values are only marginally affected.


title: Detection of molecular hydrogen at z=1.15 toward HE 0515-4414

abstract:
  A new molecular hydrogen cloud is found in the sub-damped Ly-alpha absorber
[log N(HI)=19.88+/-0.05] at the redshift z=1.15 toward the bright quasar
HE0515-4414 (zem = 1.71). More than 30 absorption features in the Lyman band
system of H2 are identified in the UV spectrum of this quasar obtained with the
Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope.
The H2-bearing cloud shows a total H2 column density N(H2)=(8.7^{+8.7}_-{4.0})
10^16 cm^-2, and a fractional molecular abundance f(H2)=(2.3^{+2.3}_{-1.1})
10^-3 derived from the H2 lines arising from the J=0-5 rotational levels of the
ground electronic vibrational state. The estimated rate of photodissociation at
the cloud edge I_0<=1.8 10^{-8} s^-1 is much higher than the mean Galactic disk
value, I_MW~=5.5 10^{-11} s^-1. This may indicate an enhanced star-formation
activity in the z=1.15 system as compared with molecular clouds at z~=3 where
I~=I_MW. We also find a tentative evidence that the formation rate coefficient
of H2 upon grain surfaces at z=1.15 is a factor of 10 larger than a canonical
Milky Way value, R_MW~=3 10^-17 cm^3 s^-1. The relative dust-to-gas ratio
estimated from the [Cr/Zn] ratio is equal to k=0.89+/-0.19 (in units of the
mean Galactic disk value), which is in good agreement with a high molecular
fraction in this system. The estimated line-of-sight size of L~=0.25 pc may
imply that the H2 is confined within small and dense filaments embedded in a
more rarefied gas giving rise to the z=1.15 sub-damped Ly-alpha absorber.


title:
Linear Thermal Instability and Formation of Clumpy Gas Clouds Including
  the Ambipolar Diffusion

abstract:
  Thermal instability is one of the most important processes in the formation
of clumpy substructure in magnetic molecular clouds. On the other hand,
ambipolar diffusion, or ion-neutral friction, has long been thought to be an
important energy dissipation mechanism in these clouds. Thus, we would
interested to investigate the effect of ambipolar diffusion on the thermal
instability and formation of clumps in the magnetic molecular clouds. For this
purpose, in the first step, we turn our attention to the linear perturbation
stage. In this way, we obtain a non-dimensional characteristic equation which
reduces to the prior characteristic equation in the absence of the magnetic
field and ambipolar diffusion. With numerical manipulation of this
characteristic equation, we conclude that there are solutions where the thermal
instability allows compression along the magnetic field but not perpendicular
to it. We infer that this aspect might be an evidence in formation of observed
disc-like (oblate) clumps in magnetic molecular clouds.


title: Short time-scale X-ray variability of Active Galactic Nuclei

abstract:
  In this work we have investigated short time-scale variability of NGC 4051
and NGC 4388. The quasi-steady QPO's time scale of 3920$\pm$17 sec was detected
for NGC 4051. For the case of NGC 4388 we investigated rapid variability of the
parameters of spectral models. To obtain these results, a new "Moving Fit"
method for processing of the trailed X-ray spectrograms was developed.


title:
RR Lyrae variables in Galactic globular clusters - I: The observational
  scenario

abstract:
  In this paper we revisit observational data concerning RR Lyrae stars in
Galactic globular clusters, presenting frequency histograms of fundamentalized
periods for the 32 clusters having more than 12 pulsators with well recognized
period and pulsation mode. One finds that the range of fundamentalized periods
covered by the variables in a given cluster remains fairly constant in varying
the cluster metallicity all over the metallicity range spanned by the cluster
sample, with the only two exceptions given by M15 and NGC6441. We conclude that
the width in temperature of the RR Lyrae instability strip appears largely
independent of the cluster metallicity. At the same time, it appears that the
fundamentalized periods are not affected by the predicted variation of
pulsators luminosity with metal abundance, indicating the occurrence of a
correlated variation in the pulsator mass. We discuss mean periods in a
selected sample of statistically significant "RR rich" clusters with no less
than 10 RRab and 5 RRc variables. One finds a clear evidence for the well known
Oosterhoff dichotomy in the mean period <Pab> of ab-type variables, together
with a similarly clear evidence for a constancy of the mean fundamentalized
period <Pf> in passing from Oosterhoff type II to type I clusters. On this
basis, the origin of the Oosterhoff dichotomy is discussed, presenting evidence
against a strong dependence of the RR Lyrae luminosity on the metal content.


title: The host galaxies of luminous quasars

abstract:
  We present results of a deep HST/WFPC2 imaging study of 17 quasars at z~0.4,
designed to determine the properties of their host galaxies. The sample
consists of quasars with absolute magnitudes in the range -24>M_V>-28, allowing
us to investigate host galaxy properties across a decade in quasar luminosity,
but at a single redshift. We find that the hosts of all the RLQs, and all the
RQQs with nuclear luminosities M_V<-24, are massive bulge-dominated galaxies,
confirming and extending the trends deduced from our previous studies. From the
best-fitting model host galaxies we have estimated spheroid and black-hole
masses, and the efficiency (with respect to Eddington luminosity) with which
each quasar is radiating. The largest inferred black-hole mass in our sample is
\~3.10^9 M_sun, comparable to those at the centres of M87 and Cygnus A. We find
no evidence for super-Eddington accretion in even the most luminous objects. We
investigate the role of scatter in the black-hole:spheroid mass relation in
determining the ratio of quasar to host-galaxy luminosity, by generating
simulated populations of quasars lying in hosts with a Schechter mass function.
Within the subsample of the highest luminosity quasars, the observed variation
in nuclear-host luminosity ratio is consistent with being the result of the
scatter in the black-hole:spheroid relation. Quasars with high nuclear-host
ratios can be explained by sub-Eddington accretion onto black holes in the
high-mass tail of the black-hole:spheroid relation. Our results imply that,
owing to the Schechter cutoff, host mass should not continue to increase
linearly with quasar luminosity, at the very highest luminosities. Any quasars
more luminous than M_V=-27 should be found in massive elliptical hosts which at
the present day would have M_V ~ -24.5.


title:
Formation of Semi-relativisitc Jets from Magnetospheres of Accreting
  Neutron Stars: Injection of Hot Bubbles into a Magnetic Tower

abstract:
  We present the results of 2.5-dimensional resistive magnetohydrodynamic (MHD)
simulations of the magnetic interaction between a weakly magnetized neutron
star and its accretion disk. General relativistic effects are simulated by
using the pseudo-Newtonian potential. We find that well-collimated jets
traveling along the rotation axis of the disk are formed by the following
mechanism: (1) The magnetic loops connecting the neutron star and the disk are
twisted due to the differential rotation between the neutron star and the disk.
(2) Twist injection from the disk initiates expansion of the loop. (3) The
expanding magnetic loops create a magnetic tower in which accelerated disk
material travel as collimated bipolar jets. The propagation speed of the
working surface of the jet is the order of 10% of the speed of light ($\sim
0.1c$). (4) Magnetic reconnection taking place inside the expanding magnetic
loops injects hot bubbles intermittently into the magnetic tower. The ejection
speed of the bubble is the order of the local Alfv\'{e}n speed of the launching
point and $\sim 0.2c$ in our simulations. (5) The hot bubbles moving inside the
tower catch up with the working surface of the jet. High energy electrons
created by the magnetic reconnection are a plausible source of radio emission.
Our model can explain the formation process of a narrow jet from a weakly
magnetized ($|{\boldmath$B_{*}$}|\le 10^{9}$ gauss) neutron star and the
correlation between radio flares of the core and of the lobe observed in Sco
X-1.


title: A Submillimetre Selected Quasar in the Field of Abell478

abstract:
  We present the discovery of a dusty quasar, SMMJ04135+10277, located behind
the galaxy cluster Abell 478. The quasar was discovered as the brightest source
in a submillimetre survey of high redshift galaxies lensed by foreground rich
clusters of galaxies in a project aimed at studying the cosmic star formation
history of dusty galaxies. With submm fluxes of S_850 = 25+-2.8 mJy and S_450 =
55+-17 mJy this object is one of the brightest submillimetre sources known.
Optical observations revealed a quasar with redshift z=2.837. The quasar was
also detected at shorter infrared wavelengths with the Infrared Space
Observatory. This object is the first quasar discovered by its submm emission.
Given the general lack of overlap between deep submm and X-ray samples, usually
interpreted as a low incidence of active nuclei in submm samples, this is an
unusual object. Analysis of number counts of quasars and of submm galaxies
bears out this suggestion. We compare the properties of SMMJ04135+10277 to
those of optically selected quasars with submm emission, and argue that the
optical faintness results from a large viewing angle with the direction of
relativistic beaming, and not from abnormally high extinction. We also find
indications that the bulk of the submm flux density is not powered by the
quasar nucleus. This conclusion is supported by analysis of the infrared
spectral energy distribution. These results are consistent with previous
observations that quasars at higher redshift tend to have a more prominent cold
dust component, most likely powered by extended star formation in the host
galaxy. The quasar is found to have a total infrared luminosity of
(2.9+-0.5)x10^13 L_sun, dominated by the emission from cool dust. (Abridged)


title:
The Canada-UK Deep Submillimeter Survey VII: Optical and near-infrared
  identifications for the 14h field

abstract:
  We present the multi-wavelength identifications for 23 sources in the
Canada-UK Deep Submillimeter Survey (CUDSS) 14h field. The identifications have
been selected on the basis of radio and near-infrared data and we argue that,
to our observational limits, both are effective at selecting the correct
counterparts of the SCUBA sources. We discuss the properties of these
identifications and find that they are very red in near-infrared color, with
many classified as Extremely Red Objects, and show disturbed morphologies.
Using the entire CUDSS catalogue of 50 sources we use a combination of
spectroscopic redshifts (4 objects), 1.4GHz-to-850um flux ratio redshift
estimates (10 objects), and redshift lower-limits based on non-detections at
1.4GHz (the rest of the sample) to estimate a lower-limit on the median
redshift of the population of z_med > 1.4. Working from simple models and using
the properties of the secure identifications, we discuss general and tentative
constraints on the redshift distribution and the expected colors and magnitudes
of the entire population.


title:
Flash Mixing on the White Dwarf Cooling Curve: FUSE Observations of
  three He-rich sdB Stars

abstract:
  We present FUSE spectra of 3 He-rich sdB stars. Two of these stars,
PG1544+488 and JL87, reveal extremely strong C III lines at 977 and 1176A,
while the carbon lines are quite weak in the third star, LB1766. We have
analyzed the FUSE data using TLUSTY NLTE line-blanketed model atmospheres, and
find that PG1544+488 has a surface composition of 96% He, 2% C, and 1% N. JL87
shows a similar surface enrichment of carbon and nitrogen, but some significant
fraction of hydrogen still remains in its atmosphere. LB1766 has a surface
composition devoid of hydrogen and strongly depleted of carbon, indicating that
its surface material has undergone CN-cycle processing. We interpret these
observations with new evolutionary calculations which suggest that He-rich sdB
stars with C-rich compositions are the progeny of stars which underwent a
delayed He-core flash on the white-dwarf cooling curve. During such a flash the
interior convection zone will penetrate into the H envelope, thereby mixing the
envelope with the He- and C-rich core. Such `flash-mixed' stars will arrive on
the extreme horizontal branch (EHB) with He- and C-rich surface compositions
and will be hotter than the hottest canonical (i.e., unmixed) EHB stars. Two
types of flash mixing are possible: `deep' and `shallow', depending on whether
the H envelope is mixed deeply into the site of the He flash or only with the
outer layers of the core. Based on both their stellar parameters and surface
compositions, we suggest that PG1544+488 and JL87 are examples of `deep' and
`shallow' flash mixing, respectively. Flash mixing may therefore represent a
new evolutionary channel for producing the hottest EHB stars. However, flash
mixing cannot explain the abundance pattern in LB1766, which remains a
challenge to current evolutionary models.


title: Accelerated closed universes in scalar-tensor theories

abstract:
  We describe an accelerating universe model in the context of a scalar-tensor
theory. This model is intrinsically closed, and is filled with
quintessence-like scalar field components, in addition to the Cold Dark Matter
component. With a background geometry specified by the
Friedman-Robertson-Walker metric, we establish conditions under which this
closed cosmological model, described in a scalar-tensor theory, may look flat
in a genuine Jordan-Brans-Dicke theory. Both models become indistinguishable at
low enough redshift.


title: Atmospheric Monitoring for the Pierre Auger Fluorescence Detector

abstract:
  Major uncertainties in the fluorescence energy measurement come from the
precision of various atmospheric transmission, air Cerenkov subtraction, light
multiple-scattering and cloud corrections. The Auger program for atmospheric
monitoring, designed to measure these corrections and to minimize these
uncertainties, is summarized in this paper.


title: The Sloan Digital Sky Survey Quasar Catalog II. First Data Release

abstract:
  We present the second edition of the Sloan Digital Sky Survey (SDSS) Quasar
Catalog. The catalog consists of 16713 objects in the SDSS First Data Release
(DR1) that have luminosities larger than M_i=-22 (H_0=70 km/s, Omega_M=0.3,
Omega_Lambda=0.7), have at least one emission line with FWHM larger than 1000
km/s, and have highly reliable redshifts. The area covered is ~1360 deg^2 and
the redshifts range from 0.08 to 5.41, with a median value of 1.43. Each object
has positions accurate to better than 0.2" rms per coordinate, five-band
(ugriz) CCD-based photometry with typical accuracy of 0.03 mag, and information
on the morphology and selection method, in addition to radio, near-infrared,
and X-ray emission properties of the quasars, when available, from other large
area surveys. Calibrated digital spectra covering 3800-9200 Angstroms at a
spectral resolution 1800-2100, are available. This publication supersedes the
first SDSS Quasar Catalog, which was based on material from the SDSS Early Data
Release. A summary of corrections to current quasar databases is provided. The
majority of the objects were found in SDSS commissioning data using a
multicolor selection technique. Since the quasar selection algorithm was
undergoing testing during the entire DR1 observational period, care must be
taken when assembling samples for use in statistical studies. A total of 15786
objects (94%) in the catalog were discovered by the SDSS; 12,173 of which are
reported here for the first time, including five quasars brighter than i=16.0
and 17 quasars with redshifts larger than 4.5.


title: The Spiros imaging software for the Integral SPI spectrometer

abstract:
  A key tool in the package of software available for the analysis of data from
the SPI spectrometer of Integral is the SPIROS system developed at the
University of Birmingham. Although intended primarily for the analysis of point
sources and for the extraction of spectral information, SPIROS has many
additional capabilities. The software is described with particular emphasis on
the most widely used modes of operation and on the relationship to other
imaging and data reduction techniques.


title: Fresnel lenses for X-ray and Gamma-ray Astronomy

abstract:
  Phase Fresnel lenses have the same imaging properties as zone plates, but
with the possibility of concentrating all of the incident power into the
primary focus, increasing the maximum theoretical efficiency from 11% to close
to 100%. For X-rays, and in particular for gamma-rays, large,
diffraction-limited phase Fresnel lenses can be made relatively easily. The
focal length is very long - for example up to a million kms. However, the
correspondingly high `plate-scale' of the image means that the ultra-high
(sub-micro-arc-second) angular resolution possible with a diffraction limited
gamma-ray lens a few metres in diameter can be exploited with detectors having
\~mm spatial resolution.
  The potential of such systems for ultra-high angular resolution astronomy,
and for attaining the sensitivity improvements desperately needed for certain
other studies, are reviewed and the advantages and disadvantages vis-a-vis
alternative approaches are discussed.
  We report on reduced-scale 'proof-of-principle tests' which are planned and
on mission studies of the implementation of a Fresnel telescope on a space
mission with lens and detector on two spacecraft separated by one million km.
Such a telescope would be capable of resolving emission from super-massive
black holes on the scale of their event horizons and would have the sensitivity
necessary to detect gamma-ray lines from distant supernovae.
  We show how diffractive/refractive optics leads to a continuum of possible
system designs between filled aperture lenses and wideband interferometric
arrays.


title:
Weak Lensing and CMB: Parameter forecasts including a running spectral
  index

abstract:
  We use statistical inference theory to explore the constraints from future
galaxy weak lensing (cosmic shear) surveys combined with the current CMB
constraints on cosmological parameters, focusing particularly on the running of
the spectral index of the primordial scalar power spectrum, $\alpha_s$. Recent
papers have drawn attention to the possibility of measuring $\alpha_s$ by
combining the CMB with galaxy clustering and/or the Lyman-$\alpha$ forest. Weak
lensing combined with the CMB provides an alternative probe of the primordial
power spectrum. We run a series of simulations with variable runnings and
compare them to semi-analytic non-linear mappings to test their validity for
our calculations. We find that a ``Reference'' cosmic shear survey with
$f_{sky}=0.01$ and $6.6\times 10^8$ galaxies per steradian can reduce the
uncertainty on $n_s$ and $\alpha_s$ by roughly a factor of 2 relative to the
CMB alone. We investigate the effect of shear calibration biases on lensing by
including the calibration factor as a parameter, and show that for our
Reference Survey, the precision of cosmological parameter determination is only
slightly degraded even if the amplitude calibration is uncertain by as much as
5%. We conclude that in the near future weak lensing surveys can supplement the
CMB observations to constrain the primordial power spectrum.


title: A High-resolution Spectrum of the R CrB Star V2552 Ophiuchi

abstract:
  Photometry and low-resolution spectroscopy have added V2552 Oph to the rare
class of R Coronae Borealis variables. We confirm this classification of V2552
Oph through a comparison of our high-resolution optical spectrum of this star
and that of R CrB and other F-type members of the class. We show that V2552 Oph
most closely resembles Y Mus and FH Sct, stars in which Sr, Y, and Zr are
enhanced.


title:
Migration of Jupiter-Family Comets and Resonant Asteroids to Near-Earth
  Space

abstract:
  The orbital evolution of about 20000 Jupiter-crossing objects and 1500
resonant asteroids under the gravitational influence of planets was
investigated. The rate of their collisions with the terrestrial planets was
estimated by computing the probabilities of collisions based on random-phase
approximations and the orbital elements sampled with a 500 yr step. The
Bulirsh-Stoer and a symplectic orbit integrators gave similar results for
orbital evolution, but sometimes gave different collision probabilities with
the Sun. For orbits close to that of Comet 2P, the mean collision probabilities
of Jupiter-crossing objects with the terrestrial planets were greater by two
orders of magnitude than for some other comets. For initial orbital elements
close to those of Comets 2P, 10P, 44P and 113P, a few objects (~0.1%) got
Earth-crossing orbits with semi-major axes a<2 AU and moved in such orbits for
more than 1 Myr (up to tens or even hundreds of Myrs). Some of them even got
inner-Earth orbits (i.e., with aphelion distance Q<0.983 AU) and Aten orbits.
Most former trans-Neptunian objects that have typical near-Earth object orbits
moved in such orbits for millions of years (if they did not disintegrate into
mini-comets), so during most of this time they were extinct comets.


title:
Formation of Massive Black Holes in Dense Star Clusters. I. Mass
  Segregation and Core Collapse

abstract:
  We study the early dynamical evolution of young, dense star clusters using
Monte Carlo simulations for systems with up to N~10^7 stars. Rapid mass
segregation of massive main-sequence stars and the development of the Spitzer
instability can drive these systems to core collapse in a small fraction of the
initial half-mass relaxation time. If the core collapse time is less than the
lifetime of the massive stars, all stars in the collapsing core may then
undergo a runaway collision process leading to the formation of a massive black
hole. Here we study in detail the first step in this process, up to the
occurrence of core collapse. We have performed about 100 simulations for
clusters with a wide variety of initial conditions, varying systematically the
cluster density profile, stellar IMF, and number of stars. We also considered
the effects of initial mass segregation and stellar evolution mass loss. Our
results show that, for clusters with a moderate initial central concentration
and any realistic IMF, the ratio of core collapse time to initial half-mass
relaxation time is typically ~0.1, in agreement with the value previously found
by direct N-body simulations for much smaller systems. Models with even higher
central concentration initially, or with initial mass segregation (from star
formation) have even shorter core-collapse times. Remarkably, we find that, for
all realistic initial conditions, the mass of the collapsing core is always
close to ~10^-3 of the total cluster mass, very similar to the observed
correlation between central black hole mass and total cluster mass in a variety
of environments. We discuss the implications of our results for the formation
of intermediate-mass black holes in globular clusters and super star clusters,
ultraluminous X-ray sources, and seed black holes in proto-galactic nuclei.


title: Migration of Interplanetary Dust

abstract:
  We numerically investigate the migration of dust particles with initial
orbits close to those of the numbered asteroids, observed trans-Neptunian
objects, and Comet Encke. The fraction of silicate asteroidal particles that
collided with the Earth during their lifetime varied from 1.1% for 100 micron
particles to 0.008% for 1 micron particles. Almost all asteroidal particles
with diameter d>4 microns collided with the Sun. The peaks in the migrating
asteroidal dust particles' semi-major axis distribution at the n:(n+1)
resonances with Earth and Venus and the gaps associated with the 1:1 resonances
with these planets are more pronounced for larger particles. The probability of
collisions of cometary particles with the Earth is smaller than for asteroidal
particles, and this difference is greater for larger particles.


title: On the Viability of Two-temperature Accretion Flows

abstract:
  Binney (2003) has argued that two-temperature radiatively inefficient
accretion flow models are unphysical because the electron-ion equipartition
time is much shorter than the accretion time. I show that this conclusion is
incorrect because it relies on a misidentification of the electron-ion
equipartition time. I also clarify what requirements must, in fact, be
satisfied to maintain a two-temperature accretion flow.


title:
Pair loading in Gamma-Ray Burst Fireball And Prompt Emission From
  Pair-Rich Reverse Shock

abstract:
  Gamma-ray bursts (GRBs) are believed to originate from ultra-relativistic
winds/fireballs to avoid the "compactness problem". However, the most energetic
photons in GRBs may still suffer from $\gamma-\gamma$ absorption leading to
electron/positron pair production in the winds/fireballs. We show here that in
a wide range of model parameters, the resulting pairs may dominate those
electrons associated with baryons. Later on, the pairs would be carried into a
reverse shock so that a shocked pair-rich fireball may produce a strong flash
at lower frequencies, i.e. in the IR band, in contrast with optical/UV emission
from a pair-poor fireball. The IR emission would show a 5/2 spectral index due
to strong self-absorption. Rapid responses to GRB triggers in the IR band would
detect such strong flashes. The future detections of many IR flashes will infer
that the rarity of prompt optical/UV emissions is in fact due to dust
obscuration in the star formation regions.


title: The first CCD photometric study of the open cluster NGC 2126

abstract:
  We present the first CCD photometric observations of the northern open
cluster NGC 2126. Data were taken on eight nights in February and December 2002
with a total time span of ~57 hours. Almost 1000 individual V-band frames were
examined to find short-period variable stars. We discovered six new variable
stars, of which one is a promising candidate for an eclipsing binary with a
pulsating component. Two stars were classified as delta Scuti stars and one as
Algol-type eclipsing binary. Two stars are slow variables with ambiguous
classification. From absolute VRI photometry we have estimated the main
characteristics of the cluster: m-M=11.0+/-0.5, E(V-I)=0.4+/-0.1,
E(V-R)=0.08+/-0.06 (E(B-V)=0.2+/-0.15) and d=1.3+/-0.6 kpc. Cluster membership
is suggested for three variable stars from their positions on the
colour-magnitude diagram.


title:
The relation between the two-point and the three-point correlation
  functions in the non-linear gravitational clustering regime

abstract:
  The connection between the two-point and the three-point correlation
functions in the non-linear gravitational clustering regime is studied. Under a
scaling hypothesis, we find that the three-point correlation function, $\zeta$,
obeys the scaling law $\zeta\propto \xi^{\frac{3m+4w-2\epsilon}{2m+2w}}$ in the
nonlinear regime, where $\xi$, $m$, $w$, and $\epsilon$ are the two-point
correlation function, the power index of the power spectrum in the nonlinear
regime, the number of spatial dimensions, and the power index of the phase
correlations, respectively. The new formula reveals the origin of the power
index of the three-point correlation function. We also obtain the theoretical
condition for which the ``hierarchical form'' $\zeta\propto\xi^2$ is
reproduced.