title: Cosmic Evolution of Quasar Clustering: Implications for the Host Haloes

abstract:
  We present detailed clustering measurements from the 2dF QSO Redshift Survey
(2QZ) in the redshift range 0.8<z<2.1. Using a flux limited sample of ~14,000
objects with effective redshift z_eff=1.47, we estimate the quasar projected
correlation function for separations 1<r/h^{-1} Mpc<20. We find that the
2-point correlation function in real space is well approximated by a power law
with slope gamma=1.5 pm 0.2 and comoving correlation length
r_0=4.8^{+0.9}_{-1.5} h^{-1} Mpc. Splitting the sample into three subsets based
on redshift, we find evidence for an increase of the clustering amplitude with
lookback time. For a fixed gamma, evolution of r_0 is detected at the 3.6 sigma
confidence level. The ratio between the quasar correlation function and the
mass autocorrelation function (derived adopting the concordance cosmological
model) is found to be scale independent. For a linear mass-clustering amplitude
sigma_8=0.8, the ``bias parameter'' decreases from b~3.9$ at z_eff=1.89 to
b~1.8 at z_eff=1.06. From the observed abundance and clustering, we infer how
quasars populate dark-matter haloes of different masses. We find that 2QZ
quasars sit in haloes with M>10^{12} M_sun and that the mean mass of their host
haloes is of the order of 10^{13} M_sun. The observed clustering is consistent
with assuming that the locally observed correlation between black-hole mass and
host-galaxy circular velocity is still valid at z>1. From the fraction of
haloes which contain active quasars, we infer that the characteristic quasar
lifetime is t_Q ~ a few x 10^7 yr at z~1 and approaches 10^8 yr at higher
redshifts.


title:
Nonlinear Development of the Secular Bar-mode Instability in Rotating
  Neutron Stars

abstract:
  We have modelled the nonlinear development of the secular bar-mode
instability that is driven by gravitational radiation-reaction (GRR) forces in
rotating neutron stars. In the absence of any competing viscous effects, an
initially uniformly rotating, axisymmetric $n=1/2$ polytropic star with a ratio
of rotational to gravitational potential energy $T/|W| = 0.181$ is driven by
GRR forces to a bar-like structure, as predicted by linear theory. The pattern
frequency of the bar slows to nearly zero, that is, the bar becomes almost
stationary as viewed from an inertial frame of reference as GRR removes energy
and angular momentum from the star. In this ``Dedekind-like'' state, rotational
energy is stored as motion of the fluid in highly noncircular orbits inside the
bar. However, in less than 10 dynamical times after its formation, the bar
loses its initially coherent structure as the ordered flow inside the bar is
disrupted by what appears to be a purely hydrodynamical, short-wavelength,
``shearing'' type instability. The gravitational waveforms generated by such an
event are determined, and an estimate of the detectability of these waves is
presented.


title:
CaII K interstellar observations towards early disc and halostars -
  Paper II; distances to IVCs and HVCs

abstract:
  We compare existing high spectral resolution (R=40,000) CaII K observations
towards 88 mainly B-type stars, and new observations at R=10,000 towards 3
stars, with 21-cm HI emission-line profiles, in order to search for optical
absorption towards known intermediate and high velocity cloud complexes. Given
certain assumptions, limits to the gas phase abundance of CaII are estimated
for the cloud components. We use the data to derive the following distances
from the Galactic plane (z); 1) Tentative lower z-height limits of 2800 pc and
4100 pc towards Complex C using lack of absorption in the spectra of HD 341617
and PG 0855+294. 2) A weak lower z-height of 1400 pc towards Complex WA-WB
using lack of absorption in EC 09470-1433 and weak lower limit of 2470 pc with
EC 09452-1403. 3) An upper z-height of 2470 pc towards a southern intermediate
velocity cloud (IVC) with v_LSR=-55 km/s using PG 2351+198. 4) Detection of a
possible IVC in CaK absorption at v_LSR=+52 km/s using EC 20104-2944. No
associated HI in emission is detected. At this position, normal Galactic
rotation predicts velocities of up to +25 km/s. The detection puts an upper
z-height of 1860 pc to the cloud. 5) Tentative HI and CaK detections towards an
IVC at +70 km/s in the direction of HVC Complex WE, sightline EC 06387-8045,
indicating that the IVC may be at a z-height lower than 1770 pc. 6) Detection
of CaK absorption in the spectrum of PG 0855+294 in the direction of IV20,
indicating that this IVC has a z-height smaller than 4100 pc. 7) A weak lower
z-height of 4300 pc towards a small HVC with v_LSR=+115 km/s at l,b=200,+52,
using lack of absorption in the CaK spectrum of PG 0955+291.


title: Quintessence Models and the Cosmological Evolution of alpha

abstract:
  The cosmological evolution of a quintessence-like scalar field, phi, coupled
to matter and gauge fields leads to effective modifications of the coupling
constants and particle masses over time. We analyze a class of models where the
scalar field potential V(phi) and the couplings to matter B(phi) admit common
extremum in phi, as in the Damour-Polyakov ansatz. We find that even for the
simplest choices of potentials and B(phi), the observational constraints on
delta alpha/alpha coming from quasar absorption spectra, the Oklo phenomenon
and Big Bang nucleosynthesis provide complementary constraints on the
parameters of the model. We show the evolutionary history of these models in
some detail and describe the effects of a varying mass for dark matter.


title:
Spitzer Space Telescope Observations of the Aftermath of Microlensing
  Event MACHO-LMC-5

abstract:
  We have carried out photometry of the microlensing event MACHO-LMC-5 with
Spitzer's IRAC ten years after the magnification of the LMC source star was
recorded. This event is unique in the annals of gravitational microlensing: the
lensing star itself has been observed using HST (once with WFPC2 and twice with
ACS/HRC). Since the separation between the source and lens at the epoch of the
Spitzer observations was $\sim0.24''$, the two stars cannot be resolved in the
Spitzer images. However, the IRAC photometry clearly establishes that the lens
is a M5 dwarf star from its infrared excess, which in turn yields a mass of
$\sim0.2 M_{\odot}$. This demonstrates the potential of Spitzer to detect the
lenses in other gravitational microlensing events.


title: New debris disk candidates: 24 micron stellar excesses at 100 Myr

abstract:
  Sixty three members of the 100 Myr old open cluster M47 (NGC 2422) have been
detected at 24 micron with Spitzer. The Be star V 378 Pup shows an excess both
in the near-infrared and at 24 micron (K-[24] = 2.4 mag), probably due to
free-free emission from the gaseous envelope. Seven other early-type stars show
smaller excesses, K-[24] = 0.6-0.9. Among late-type stars, two show large
excesses: P922 - a K1V star with K-[24] = 1.08 pm 0.11 and P1121 - an F9V star
with K-[24] = 3.72 pm 0.02. P1121 is the first known main-sequence star showing
an excess comparable to that of beta Pic, which may indicate the presence of an
exceptionally massive debris disk. It is possible that a major planetesimal
collision has occurred in this system, consistent with the few hundred Myr time
scales estimated for the clearing of the Solar System.


title: Super-solar N/C in the NLS1 Galaxy Markarian 1044

abstract:
  Narrow-Line Seyfert 1s (NLS1s) are known to have extreme values of a number
of properties compared to Active Galactic Nuclei (AGN) as a class. In
particular, previous emission-line studies have suggested that NLS1s are
unusually metal rich compared to broad-line AGN of comparable luminosity. We
present low- and medium-resolution spectroscopic observations of the NLS1
Markarian 1044 with the Hubble Space Telescope Imaging Spectrometer (STIS). We
identify two blueshifted intrinsic absorption systems at -1145 and -295 km/s
relative to the systemic velocity of the galaxy. Using a simple photoionization
model of the absorbing gas, we find that the strongest and best-measured of the
absorption systems has N/C approximately 6.96 times the solar value. We also
report on the discovery of three new Ly-alpha forest lines with neutral
Hydrogen column density log greater than 12.77 in the log. This number is
consistent with the 2.6 expected in the path length to the source redshift of
Mrk 1044.


title: Gradient instability for w < -1

abstract:
  We show that in single scalar field models of the dark energy with equations
of state satisfying $w \equiv p / \rho < -1$, the effective Lagrangian for
fluctuations about the homogeneous background has a wrong sign spatial kinetic
term. In most cases, spatial gradients are ruled out by microwave background
observations. The sign of $w+1$ is not connected to the sign of the time
derivative kinetic term in the effective Lagrangian.


title: A 2 x 2 Degree I-band Survey around PKS 1343-601

abstract:
  Motivated by the possibility that the highly obscured (A_B = 12 mag) radio
galaxy PKS 1343-601 at (l,b,cz) = (309.7, +1.8, 3872km/s) might constitute the
center of a heavily obscured cluster in the Great Attractor region, we have
imaged about 2 x 2 degree of the core of this prospective cluster in the I-band
using the WFI at the ESO 2.2m telescope at La Silla. We were able to identify
49 galaxies and 6 uncertain galaxy candidates. Although their distribution does
not resemble a centrally condensed, massive cluster, its appearance -- severely
influenced by the strong dust gradient across our surveyed region -- is
entirely consistent with a cluster.


title: Kinematics of X-ray Emitting Components in Cassiopeia A

abstract:
  We present high-resolution X-ray proper motion measurements of Cassiopeia A
using Chandra observations from 2000 and 2002. We separate the emission into
four spectrally distinct classes: Si-dominated, Fe-dominated,
low-energy-enhanced, and continuum-dominated. These classes also represent
distinct spatial and kinematic components. The Si- and Fe-dominated classes are
ejecta and have a mean expansion rate of 0.2%/yr. This is the same as for the
forward shock filaments but less than the 0.3%/yr characteristic of optical
ejecta. The low-energy-enhanced spectral class possibly illuminates a clumpy
circumstellar component and has a mean expansion rate of 0.05%/yr. The
continuum-dominated emission likely represents the forward shock and consists
of diffuse circumstellar material which is seen as a circular ring around the
periphery of the remnant as well as projected across the center.


title:
Constraints on Resonant Particle Production during Inflation from the
  Matter and CMB Power Spectra

abstract:
  We analyze the limits on resonant particle production during inflation based
upon the power spectrum of fluctuations in matter and the cosmic microwave
background. We show that such a model is consistent with features observed in
the matter power spectrum deduced from galaxy surveys and damped Lyman-alpha
systems at high redshift. It also provides an alternative explanation for the
excess power observed in the power spectrum of the cosmic microwave background
fluctuations in the range of 1000 < l < 3500. For our best-fit models, epochs
of resonant particle creation reenter the horizon at wave numbers ~ 0.4 and/or
0.2 (h/Mpc). The amplitude and location of these features correspond to the
creation of fermion species of mass ~ 1-2 Mpl during inflation with a coupling
constant between the inflaton field and the created fermion species of near
unity. Although the evidence is marginal, if this interpretation is correct,
this could be one of the first observational hints of new physics at the Planck
scale.


title: Intermediate-mass Black Holes in Galactic Nuclei

abstract:
  We present the first homogeneous sample of intermediate-mass black hole
candidates in active galactic nuclei. Starting with broad-line active nuclei
from the Sloan Digital Sky Survey, we use the linewidth-luminosity-mass scaling
relation to select a sample of 19 galaxies in the mass range M_BH ~ 8 x 10^4 -
10^6 solar masses. In contrast to the local active galaxy population, the host
galaxies are ~1 mag fainter than M* and thus are probably late-type systems.
The active nuclei are also faint, with M_g ~ -15 to -18 mag, while the
bolometric luminosities are close to the Eddington limit. The spectral
properties of the sample are compared to the related class of objects known as
narrow-line Seyfert 1 galaxies. We discuss the importance of our sample as
observational analogues of primordial black holes, contributors to the
integrated signal for future gravitational wave experiments, and as a valuable
tool in the calibration of the M-sigma relation.


title:
Stabilization of the Shear Instability in a Dust Layer of a
  Protoplanetary Disk and Possible Formation of Planetesimals due to
  Gravitational Fragmentation of the Dust Layer

abstract:
  We show that the planetesimal formation due to the gravitational
fragmentation of a dust layer in a protoplanetary disk is possible. The dust
density distribution in the dust layer would approach the constant Richardson
number distribution due to the dust stirring by the shear instability and dust
settling. We perform the analysis of the shear instability of dust layer in a
protoplanetary disk with the constant Richardson number density distribution.
Our study revealed that this distribution is stable against the shear
instability even if the dust density at the midplane reaches the critical
density of the gravitational instability, and the planetesimal formation
through the gravitational fragmentation of the dust layer can occur even for
the dust to gas surface density ratio with the solar composition.


title:
Discovery of a large-scale filament connected to the massive galaxy
  cluster MACSJ0717.5+3745 at z=0.55

abstract:
  We report the detection of a 4/h70 Mpc long large-scale filament leading into
the massive galaxy cluster MACS J0717.5+3745. The extent of this object well
beyond the cluster's nominal virial radius (~2.3 Mpc) rules out prior
interaction between its constituent galaxies and the cluster and makes it a
prime candidate for a genuine filament as opposed to a merger remnant or a
double cluster. The structure was discovered as a pronounced overdensity of
galaxies selected to have V-R colors close to the cluster red sequence.
Extensive spectroscopic follow-up of over 300 of these galaxies in a region
covering the filament and the cluster confirms that the entire structure is
located at the cluster redshift of z=0.545. Featuring galaxy surface densities
of typically 15/Mpc^2 down to luminosities of 0.10 L(*,V), the most diffuse
parts of the filament are comparable in density to the clumps of red galaxies
found around A851 in the only similar study carried out to date (Kodama et
al.). Our direct detection of an extended large-scale filament funneling matter
onto a massive, distant cluster provides a superb target for in-depth studies
of the evolution of galaxies in environments of greatly varying density, and
supports the predictions from theoretical models and numerical simulations of
structure formation in a hierarchical picture.


title: ISO spectroscopy of disks around Herbig Ae/Be stars

abstract:
  We have investigated the infrared spectra of all 46 Herbig Ae/Be stars for
which spectroscopic data is available in the ISO data archive. Our quantitative
analysis of these spectra focusses on the emission bands linked to polycyclic
aromatic hydrocarbons (PAHs), the amorphous 10 micron silicate band and the
crystalline silicate band at 11.3 micron. We have detected PAH emission in 57%
of the Herbig stars in our sample. Clear examples of differences in the PAH
spectra are present within our sample, indicating differences in PAH size,
chemistry and/or ionization. Amorphous silicate emission was detected in the
spectra of 52% of the sample stars, amorphous silicate absorption in 13%. We
have detected crystalline silicate emission in 11 stars (24% of our sample), of
which four (9%) also display strong PAH emission. We have classified the sample
sources according to the strength of their mid-IR energy distribution. The
systems with stronger mid-infared (20-100 um) excesses relative to their
near-infrared (1-5 um) excess display significantly more PAH emission than
those with weaker mid-infrared excesses. This provides strong observational
support for the disk models by Dullemond (2002), in which systems with a
flaring disk geometry display a strong mid-infrared excess, whereas those with
disks that are strongly shadowed by the puffed-up inner rim of the disk only
display modest amounts of mid-infrared emission. The PAH emission is expected
to be produced mainly in the part of the disk atmosphere that is directly
exposed to radiation from the central star. In this model, self-shadowed disks
should display weaker PAH emission than flared disks, consistent with our
observations.


title:
Capture of cosmic objects by central gravitational field of a galaxy
  cluster

abstract:
  The effect of capture of a cosmic object by the central gravitational field
of a galaxy cluster is described in the expanding Universe. The cosmic
evolution can be the origin of the capture explaining formation of galaxies and
their clusters from the homogenous distribution of matter in the Universe. The
Newton-like equation of the capture is derived for arbitrary equations of state
in terms of the red shift parameter, and the influence of the Hubble velocities
on the rotational curves is studied. The obtained rotational curves show us
that the deficit of the visible matter for superclusters $M\sim
10^{15}M_{\odot}$ can be increased in the version of cosmology where
observational quantities are identified with the conformal ones.


title: INTEGRAL broadband spectroscopy of Vela X-1

abstract:
  The wind-accreting X-ray binary pulsar and cyclotron line source Vela X-1 has
been observed extensively during INTEGRAL Core Program observations of the Vela
region in June-July and November-December 2003. In the latter set of
observations the source showed intense flaring -- see also Staubert et al.
(2004), these proceedings.
  We present early results on time averaged and time resolved spectra, of both
epochs of observations. A cyclotron line feature at ~53 keV is clearly detected
in the INTEGRAL spectra and its broad shape is resolved in SPI spectra. The
remaining issues in the calibration of the instruments do not allow to resolve
the question of the disputed line feature at 20-25 keV.
  During the first main flare the average luminosity increases by a factor of
\~10, but the spectral shape remains very similar, except for a moderate
softening.


title:
Warm water vapor envelope in the supergiants alf Ori and alf Her and its
  effects on the apparent size from the near-infrared to the mid-infrared

abstract:
  We present a possible interpretation for the increase of the angular diameter
of the supergiants alf Ori (M1-2 Ia-Ibe) and alf Her (M5 Ib-II) from the K band
to the 11 micron region and the high-resolution 11 micron spectra without any
salient spectral features revealed by Weiner et al. (2003). The angular
diameters as well as the high-resolution spectra of alf Ori and alf Her
obtained in the 11 micron region can be reproduced by a warm water vapor
envelope, whose presence in alf Ori was revealed by Tsuji (2000) based on the
reanalysis of the near-infrared data obtained with the Stratoscope II. While
prominent absorption due to H2O can be expected from such a dense, warm water
vapor envelope, the absorption lines can be filled in by emission from the
extended part of the envelope. This effect leads to a significant weakening of
the H2O lines in the 11 micron region, and makes the observed spectra appear to
be rather featureless and continuum-like. However, the emission due to H2O
lines from the extended envelope leads to an increase of the apparent size in
this spectral region. The observed angular diameter and the high resolution
spectra of alf Ori and alf Her in the 11 micron region can be best interpreted
by the water vapor envelope extending to 1.4--1.5 Rstar, with a temperature of
about 2000 K and a column density of H2O of the order of 10^20 cm^-2.


title:
Evaporation of ices near massive stars: models based on laboratory TPD
  data

abstract:
  Hot cores and their precursors contain an integrated record of the physics of
the collapse process in the chemistry of the ices deposited during that
collapse. In this paper, we present results from a new model of the chemistry
near high mass stars in which the desorption of each species in the ice mixture
is described as indicated by new experimental results obtained under conditions
similar to those hot cores. Our models show that provided there is a monotonic
increase in the temperature of the gas and dust surrounding the protostar, the
changes in the chemical evolution of each species due to differential
desorption are important. The species H$_2$S, SO, SO$_2$, OCS, H$_2$CS, CS, NS,
CH$_3$OH, HCOOCH$_3$, CH$_2$CO, C$_2$H$_5$OH show a strong time dependence that
may be a useful signature of time evolution in the warm-up phase as the star
moves on to the Main Sequence. This preliminary study demonstrates the
consequences of incorporating reliable TPD data into chemical models.


title: The tidal trail of NGC205?

abstract:
  Using data taken as part of the Isaac Newton Telescope Wide Field Camera (INT
WFC) survey of M31, we have identified an arc-like overdensity of blue,
presumably metal-poor, red giant branch stars in the north-west quadrant of
M31. This feature is approximately 1 degree (15 kpc) in extent and has a
surface brightness of Sigma_V' ~ 28.5 +/- 0.5 mags per sq. arcsec. The arc
appears to emanate from the dwarf elliptical galaxy NGC205, and the colour of
its red giant branch is significantly different to the M31 disk population but
closely resembles that of NGC205. Further, using data taken with the DEep
Imaging Multi-Object Spectrograph (DEIMOS) on Keck II, we identify the radial
velocity signature of this arc. Its velocity dispersion is measured to be
approximately 10km/s, similar to that of the central regions of NGC205 and
typical of stellar streams. Based upon the spatial coincidence of these
objects, the surface brightness, the velocity dispersions and the similarity in
colour of the red giant branches, we postulate that the arc is part of a
stellar stream, the progenitor of which is NGC205.


title:
Discovery of optically faint obscured quasars with Virtual Observatory
  tools

abstract:
  We use Virtual Observatory (VO) tools to identify optically faint, obscured
(i.e., type 2) active galactic nuclei (AGN) in the two Great Observatories
Origins Deep Survey (GOODS) fields. By employing publicly available X-ray and
optical data and catalogues we discover 68 type 2 AGN candidates. The X-ray
powers of these sources are estimated by using a previously known correlation
between X-ray luminosity and X-ray-to-optical flux ratio. Thirty-one of our
candidates have high estimated powers (Lx > 10^44 erg/s) and therefore qualify
as optically obscured quasars, the so-called ``QSO 2''. Based on the derived
X-ray powers, our candidates are likely to be at relatively high redshifts, z ~
3, with the QSO 2 at z ~ 4. By going ~ 3 magnitudes fainter than previously
known type 2 AGN in the two GOODS fields we are sampling a region of redshift -
power space which was previously unreachable with classical methods. Our method
brings to 40 the number of QSO 2 in the GOODS fields, an improvement of a
factor ~ 4 when compared to the only 9 such sources previously known. We derive
a QSO 2 surface density down to 10^-15 erg/cm^2/s in the 0.5 - 8 keV band of >~
330/deg^2, ~ 30% of which is made up of previously known sources. This is
larger than current estimates and some predictions and suggests that the
surface density of QSO 2 at faint flux limits has been underestimated. This
work demonstrates that VO tools are mature enough to produce cutting-edge
science results by exploiting astronomical data beyond ``classical''
identification limits (R <~ 25) with interoperable tools for statistical
identification of sources using multiwavelength information.


title:
Chandra observations of the accretion-driven millisecond X-ray pulsars
  XTE J0929-314 and XTE J1751-305 in quiescence

abstract:
  (Abridge) We observed the accreting millisecond X-ray pulsars XTE J0929-314
and XTE J1751-305 in their quiescent states using Chandra. From XTE J0929-314
we detected 22 photons (0.3-8 keV) in 24.4 ksec, resulting in a count rate of 9
x 10^{-4} c/s. The small number of photons detected did not allow for a
detailed spectral analysis, but we can demonstrate that the spectrum is harder
than simple thermal emission which is what is usually presumed to arise from a
cooling neutron star that has been heated during the outbursts. Assuming a
power-law model for the spectrum, we obtain a power-law index of ~1.8 and an
unabsorbed flux of 6 x 10^{-15} ergs/s/cm^2 (0.5-10 keV), resulting in a
luminosity of 7 x 10^{31} (d/10 kpc)^2 ergs/s, with d in kpc. No thermal
component could be detected; such a component contributed at most 30% to the
0.5-10 keV flux. Variability in the count rate of XTE J0929-314 was observed at
the 95% confidence level. We did not conclusively detect XTE J1751-305 in our
43 ksec observation, with 0.5-10 keV flux upper limits between 0.2 and 2.7 x
10^{-14} ergs/s/cm^2 depending on assumed spectral shape, resulting in
luminosity upper limits of 0.2 - 2 x 10^{32} (d/8 kpc)^2 ergs/s. We compare our
results with those obtained for other neutron-star X-ray transients in their
quiescent state. Using simple accretion disk physics in combination with our
measured quiescent luminosity of XTE J0929-314 and the luminosity upper limits
of XTE J1751-305, and the known spin frequency of the neutron stars, we could
constrain the magnetic field of the neutron stars in XTE J0929-314 and XTE
J1751-305 to be less than 3 x 10^9 (d/10 kpc) and 3 - 7 x 10^8 (d/8 kpc) Gauss
(depending on assumed spectral shape of the quiescent spectrum), respectively.


title: The INTEGRAL/SPI response and the Crab observations

abstract:
  The Crab region was observed several times by INTEGRAL for calibration
purposes. This paper aims at underlining the systematic interactions between
(i) observations of this reference source, (ii) in-flight calibration of the
instrumental response and (iii) the development and validation of the analysis
tools of the SPI spectrometer. It first describes the way the response is
produced and how studies of the Crab spectrum lead to improvements and
corrections in the initial response. Then, we present the tools which were
developed to extract spectra from the SPI observation data and finally a Crab
spectrum obtained with one of these methods, to show the agreement with
previous experiments. We conclude with the work still ahead to understand
residual uncertainties in the response.


title:
Mean diurnal variations of cosmic ray intensity as measured by Andyrchi
  air shower array and Baksan underground scintillation telescope

abstract:
  The results of measuring diurnal variations of extensive air showers with
energy above 100 TeV detected by the Andyrchi air shower array in 1995-2002 are
presented. It is shown that solar diurnal wave of intensity is formed by
pressure variations and Compton-Getting effect (due to the orbital motion of
the Earth). The data on cosmic ray anisotropy of the Baksan underground
scintillation telescope (BUST) are also presented for energies above 2.5 TeV
covering the period 1982-1998. The diurnal sidereal wave measured by both
Andyrchi and BUST is due to anisotropy of the cosmic rays.


title: The Importance of Lens Galaxy Environments

abstract:
  While many strong gravitational lens galaxies are suspected to lie in groups
or clusters of galaxies, environmental effects in lens models are often
unconstrained and sometimes ignored. We show that this creates significant
biases in a variety of lensing applications, by creating mock lenses associated
with each of 13 galaxies in a realistic model group, and then analyzing them
with standard techniques. We find that standard models of double lenses, which
neglect environment, grossly overestimate the ellipticity of the lens galaxy
(de/e~0.5) and the Hubble constant (dh/h~0.22). Standard models of quad lenses,
which approximate the environment as a tidal shear, recover the ellipticity
reasonably well (|de/e|<~0.24) but overestimate the Hubble constant
(dh/h~0.15), and have significant (~30%) errors in the millilensing analyses
used to constrain the amount of substructure in dark matter halos. For both
doubles and quads, standard models slightly overestimate the velocity
dispersion of the lens galaxy (d(sigma)/sigma~0.06), and underestimate the
magnifications of the images (d(mu)/mu ~ -0.25). Standard analyses of lens
statistics overestimate Omega_Lambda (by 0.05-0.14), and underestimate the
ratio of quads to doubles (by a factor of 2). These biases help explain some
long-standing puzzles (such as the high observed quad/double ratio), but
aggravate others (such as the low value of H_0 inferred from lensing). Most of
the biases are caused by neglect of the convergence from the mass associated
with the environment, but additional uncertainty is introduced by neglect of
higher-order terms. Fortunately, we show that directly observing and modeling
lens environments should make it possible to remove the biases and reduce the
uncertainties associated with environments to the few percent level. (Abridged)


title:
Exploring the Gamma Ray Horizon with the next generation of Gamma Ray
  Telescopes. Part 2: Extracting cosmological parameters from the observation
  of gamma-ray sources

abstract:
  The potential of the new generation Cherenkov Telescopes to measure the
energy spectrum of both, the already established extragalactic very high energy
gamma-ray emitters and the best very high energy candidates from the EGRET
catalogue is discussed. By a realistic simulation of the analysis of the
expected extrapolated energy spectra, it is shown that the foreseen capability
and precision of these instrument to measure the Gamma Ray Horizon may open the
door to competitive measurements of the cosmological parameters.


title:
The Parsec-scale Radio Structure of NGC 1068 and the Nature of the
  Nuclear Radio Source

abstract:
  We present sensitive, multifrequency Very Long Baseline Array (VLBA) images
of the nuclear radio sources of NGC 1068. At 5 GHz and 8.4 GHz, the radio
continuum source S1, argued to mark the location of the hidden active nucleus,
resolves into an elongated, ~ 0.8 pc source oriented nearly at right angles to
the radio jet axis but more closely aligned to the distribution of the nuclear
H2O maser spots. S1 is detected at 5 GHz but not at 1.4 GHz, indicating strong
free-free absorption below 5 GHz, and it has a flat spectrum between 5 GHz and
8.4 GHz. A 5/8.4 GHz spectral index map reveals an unresolved, inverted
spectrum source at the center of the S1 structure which may mark the AGN
proper. The average brightness temperature is too low for synchrotron
self-absorption to impact the integrated spectrum significantly. In addition, a
careful registration with the nuclear H2O masers argues that the S1 continuum
source arises from the inner regions of the maser disk rather than a radio jet.
The emission mechanism may be direct, thermal free-free emission from an
X-ray-heated corona or wind arising from the molecular disk. We demonstrate
that the hidden active nucleus is sufficiently luminous, to within the current
estimates, to provide the requisite heating.


title: Scaling defect decay and the reionization history of the Universe

abstract:
  We consider a model for the reionization history of the Universe in which a
significant fraction of the observed optical depth is a result of direct
reionization by the decay products of a scaling cosmic defect network. We show
that such network can make a significant contribution to the reionization
history of the Universe even if its energy density is very small (the defect
energy density has to be greater than about $10^{-11}$ of the background
density). We compute the Cosmic Microwave Background temperature, polarization
and temperature-polarization cross power spectrum and show that a contribution
to the observed optical depth due to the decay products of a scaling defect
network may help to reconcile a high optical depth with a low redshift of
complete reionization suggested by quasar data. However, if the energy density
of defects is approximately a constant fraction of the background density then
these models do not explain the large scale bump in the
temperature-polarization cross power spectrum observed by WMAP.


title:
Spatially Resolved Ultraviolet, H-alpha, Infrared, and Radio Star
  Formation in M81

abstract:
  We present Multiband Imaging Photometer for Spitzer (MIPS) observations of
M81 at 24, 70, and 160 micron. The grand design nature of M81 is clearly seen,
showing two well resolved spiral arms containing numerous bright star forming
regions. The MIPS images reveal a significant amount of cold dust associated
with the spiral arms. We investigate the variation of the ultraviolet (UV),
H-alpha, and infrared (IR) luminosities and star formation rate (SFR)
indicators across the face of M81 using the MIPS images and archival UV and
H-alpha images. For regions in M81, we find that UV and H-alpha SFRs
(uncorrected for dust attenuation) are always lower than the IR SFR. The cause
of this behavior is dust attenuation and/or using SFR calibrations appropriate
for entire galaxies, not regions in galaxies. The characteristics of the dust
attenuation for the regions indicate the dust grains and/or geometry are
different from those in starburst galaxies. The behavior of the infrared-radio
correlation in M81 is seen to vary from the global average, with variations
correlated with the morphology of M81.


title: The 24-Micron View of Embedded Star Formation in NGC 7129

abstract:
  We present observations of the star formation region NGC 7129 taken with the
Multiband Imaging Photometer for Spitzer (MIPS). A significant population of
sources, likely pre-main sequence members of the young stellar cluster, is
revealed outside the central photoionization region. Combining with Infrared
Array Camera (IRAC) and ground-based near-infrared images, we have obtained
colors and spectral energy distributions for some 60 objects. The [3.6]-[4.5]
vs. [8]-[24] color-color plane shows sources clustered at several different
loci, which roughly correspond to the archetypal evolutionary sequence Class 0,
I, II, and III. We obtain preliminary classifications for 36 objects, and find
significant numbers of both Class I and II objects. Most of the pre-main
sequence candidates are associated with the densest part of the molecular cloud
surrounding the photoionization region, indicating active star formation over a
broad area outside the central cluster. We discuss three Class II candidates
that exhibit evidence of inner disk clearing, which would be some of the
youngest known examples of a transition from accretion to optically thin
quiescent disks.


title:
Systematic Search for Short-transients and Pulsation Events from
  INTEGRAL Survey Data

abstract:
  The imaging instruments on board INTEGRAL have wide fields of view and high
time resolution. Therefore, they are ideal instruments to search for pulsating
sources and/or transient events. We are systematically searching for pulsations
and transient events from known and serendipitous sources in the Galactic Plane
Scan (GPS) and Galactic Center Deep Exposure (GCDE) core program data. We
analyze the standard pipe-line data using
  ISDC Off-line Science Analysis (OSA) system, so that our results are
reproducible by general guest users. In this paper, we describe our system and
report preliminary results for the first year of operation.


title: The RR Lyrae Period-Luminosity Relation. I. Theoretical Calibration

abstract:
  We present a theoretical calibration of the RR Lyrae period-luminosity (PL)
relation in the UBVRIJHK Johnsons-Cousins-Glass system. Our theoretical work is
based on calculations of synthetic horizontal branches (HBs) for several
different metallicities, fully taking into account evolutionary effects besides
the effect of chemical composition. Extensive tabulations of our results are
provided, including convenient analytical formulae for the calculation of the
coefficients of the period-luminosity relation in the different passbands as a
function of HB type. We also provide "average" PL relations in IJHK, for
applications in cases where the HB type is not known a priori; as well as a new
calibration of the M_V - [M/H] relation. These can be summarized as follows:
  M_I = +0.471 - 1.132 log P + 0.205 log Z,
  M_J = -0.141 - 1.773 log P + 0.190 log Z,
  M_H = -0.551 - 2.313 log P + 0.178 log Z,
  M_K = -0.597 - 2.353 log P + 0.175 log Z, and M_V = +2.288 + 0.882 log Z +
0.108 (log Z)^2.


title: Chandra Observations of the NLS1 RX J2217.9-5941

abstract:
  We report the results of two Chandra ACIS-S observations from February and
August 2003 of the highly X-ray variable Narrow-Line Seyfert 1 galaxy RX
J2217.9--5941. Observations spanning the time from the ROSAT All Sky Survey
(RASS) through an ASCA observation in 1998 indicate apparently monotonically
decreasing flux by a factor of 30. The Chandra observations reveal increased
emission over that seen in ASCA, supporting a persistent variability rather
than an X-ray outburst event. However, the cause of the strong X-ray
variability remains unclear. Our Chandra observations confirm the steep soft
X-ray spectrum in the 0.2-2.0 keV band found during the ROSAT All-Sky Survey
observation (\ax=2.7). The spectral shape of the source appears to be variable
with the spectrum becoming softer when the source becomes fainter. Best fitting
models to the data include an absorbed broken power law, a blackbody plus power
law, and a power law with partial covering absorption. The latter model
suggests a variable partial-covering absorber in the line of sight which can
explain in part the variability seen in RX J2217.9--5941. We suggest that there
might be a population of Narrow Line Seyfert 1 galaxies which are at least at
times highly absorbed.


title: Can the faint sub-mm galaxies be explained in the Lambda-CDM model?

abstract:
  We present predictions for the abundance of sub-mm galaxies (SMGs) and
Lyman-break galaxies (LBGs) in the $\Lambda$CDM cosmology. A key feature of our
model is the self-consistent calculation of the absorption and emission of
radiation by dust. The new model successfully matches the LBG luminosity
function, as well reproducing the properties of the local galaxy population in
the optical and IR. The model can also explain the observed galaxy number
counts at $850\mum$, but only if we assume a top-heavy IMF for the stars formed
in bursts. The predicted redshift distribution of SMGs depends relatively
little on their flux over the range 1-$10\mjy$, with a median value of
$z\approx 2.0$ at a flux of $5\mjy$, in very good agreement with the recent
measurement by Chapman et al The counts of SMGs are predicted to be dominated
by ongoing starbursts. However, in the model these bursts are responsible for
making only a few per cent of the stellar mass locked up in massive ellipticals
at the present day.


title:
On the Maximum Luminosity of Galaxies and Their Central Black Holes:
  Feedback From Momentum-Driven Winds

abstract:
  We investigate large-scale galactic winds driven by momentum deposition.
Momentum injection is provided by (1) radiation pressure produced by the
continuum absorption and scattering of UV photons on dust grains and (2)
supernovae. UV radiation can be produced by a starburst or AGN activity. We
argue that momentum-driven winds are an efficient mechanism for feedback during
the formation of galaxies. We show that above a limiting luminosity, momentum
deposition from star formation can expel a significant fraction of the gas in a
galaxy. The limiting, Eddington-like luminosity is $L_{\rm M}\simeq(4f_g c/G)
\sigma^4$, where $\sigma$ is the galaxy velocity dispersion and $f_g$ is the
gas fraction. A starburst that attains $L_{\rm M}$ moderates its star formation
rate and its luminosity does not increase significantly further. We argue that
ellipticals attain this limit during their growth at $z \gtrsim 1$ and that
this is the origin of the Faber-Jackson relation. We show that Lyman break
galaxies and ultra-luminous infrared galaxies have luminosities near $L_{\rm
M}$. Star formation is unlikely to efficiently remove gas from very small
scales in galactic nuclei, i.e., scales much smaller than that of a nuclear
starburst. This gas is available to fuel a central black hole (BH). We argue
that a BH clears gas out of its galactic nucleus when the luminosity of the BH
itself reaches $\approx L_{\rm M}$. This shuts off the fuel supply to the BH
and may also terminate star formation in the surrounding galaxy. As a result,
the BH mass is fixed to be $M_{\rm BH}\simeq (f_g \kappa_{\rm es}/\pi
G^2)\sigma^4$, where $\kappa_{\rm es}$ is the electron scattering opacity. This
limit is in accord with the observed $M_{\rm BH}-\sigma$ relation. (Abridged)


title: The Stability of Magnetized Rotating Plasmas with Superthermal Fields

abstract:
  During the last decade it has become evident that the magnetorotational
instability is at the heart of the enhanced angular momentum transport in
weakly magnetized accretion disks around neutron stars and black holes. In this
paper, we investigate the local linear stability of differentially rotating,
magnetized flows and the evolution of the magnetorotational instability beyond
the weak-field limit. We show that, when superthermal toroidal fields are
considered, the effects of both compressibility and magnetic tension forces,
which are related to the curvature of toroidal field lines, should be taken
fully into account. We demonstrate that the presence of a strong toroidal
component in the magnetic field plays a non-trivial role. When strong fields
are considered, the strength of the toroidal magnetic field not only modifies
the growth rates of the unstable modes but also determines which modes are
subject to instabilities. We find that, for rotating configurations with
Keplerian laws, the magnetorotational instability is stabilized at low
wavenumbers for toroidal Alfven speeds exceeding the geometric mean of the
sound speed and the rotational speed. We discuss the significance of our
findings for the stability of cold, magnetically dominated, rotating fluids and
argue that, for these systems, the curvature of toroidal field lines cannot be
neglected even when short wavelength perturbations are considered. We also
comment on the implications of our results for the validity of shearing box
simulations in which superthermal toroidal fields are generated.


title:
Variability of Narrow, Associated Absorption Lines in Moderate- and
  Low-Redshift Quasars

abstract:
  We present the results of a search for variability in the equivalent widths
(EWs) of narrow, associated (Delta v < 5,000 km/s) absorption lines found in
the UV spectra of z < 1.5 quasars. The goal of this search was to use
variability as a means of identifying absorption lines arising in gas that is
intrinsic to the quasar central engine. We have compared archival HST/FOS
spectra of quasars with recent spectra obtained as part of our own snapshot
survey of the same objects with STIS. The intervals between observations are
4-10 years. We primarily focused on the C IV absorption lines, although we also
studied other lines available in the same spectra (e.g., Ly-alpha, N V, O VI).
Our main result is that 4 out of 15 quasars, or 4 out of 19 associated
absorption systems, contained variable narrow absorption lines, which are
indicative of intrinsic absorption. We conclude that a minimum of 21% of the
associated absorption-line systems are variable. Because not all systems will
have necessarily varied, this is a lower limit on this fraction and it is
consistent with previous estimates based on variability, partial coverage
analysis, or statistical arguments. If we interpret the upper limits on the
variability time scale as upper limits on the recombination time of the
absorber, we constrain the density of the absorber to be n_e > 3000 cm^{-3} and
its distance from the ionizing source to be R < 100pc. Moreover, we are now
able to pick out specific intrinsic absorption-line systems to be followed up
with high-dispersion spectroscopy in order to constrain the geometry, location,
and physical conditions of the absorber. We briefly illustrate how followup
studies can yield such constraints by means of a simulation.


title:
Spectral Methods for Time-Dependent Studies of Accretion Flows. I.
  Two-dimensional, Viscous, Hydrodynamic Disks

abstract:
  We present a numerical method for studying the normal modes of accretion
flows around black holes. In this first paper, we focus on two-dimensional,
viscous, hydrodynamic disks, for which the linear modes have been calculated
analytically in previous investigations. We use pseudo-spectral methods and low
storage Runge-Kutta methods to solve the continuity equation, the Navier-Stokes
equation, and the energy equation. We devise a number of test problems to
verify the implementation. These tests demonstrate the ability of spectral
methods to handle accurately advection problems and to reproduce correctly the
stability criteria for differentially rotating hydrodynamic flows. They also
show that our implementation is able to handle sound wave correctly with
non-reflective boundary conditions, to recover the standard solution for a
viscous spreading ring, and produce correctly the Shakura-Sunyaev steady disk
solution. Finally, we have applied our algorithm to the problem of a
non-axisymmetric viscous spreading ring and verify that such configuration is
unstable to non-antisymmetric perturbations.


title:
Spitzer-IRS Sectroscopy of the Prototype Wolf-Rayet star EZ CMa (HD
  50896)

abstract:
  We present mid-infrared Spitzer-IRS spectroscopy of the prototype WN star EZ
CMa (HD50896, WN4b). Numerous stellar wind lines of HeII are revealed, plus
fine-structure lines of [NeIII] 15.5um and [OIV] 25.9um. We carry out a
spectroscopic analysis of HD50896 allowing for line blanketing and clumping,
which is compared to the mid-IR observations. We make use of these stellar
properties to accurately derive Ne/He=1.2-1.8E-4 and O/He=4.2-4.8E-5 by number,
for the first time in an early WN star. In addition, we obtain N/C=40 and
N/O=50 by number, values in perfect agreement with current predictions for
rotating massive stars at the end of interior hydrogen burning.


title: Velocity of galaxies with different luminosity

abstract:
  We present the first determination of the pairwise velocity dispersion of
galaxies at different luminosity with the final release of the Two-Degree Field
Galaxy Redshift Survey (2dFGRS). Our result surprisingly shows that the random
velocities of the faint galaxies are very high, around $ 700 \kms$, reaching
similar values as the brightest galaxies. At intermediate luminosities slightly
brighter than the characteristic luminosity $M_\star$, the velocities exhibit a
well defined steep minimum near $ 400 \kms$. The result challenges the current
halo model of galaxies of Yang et al. that was obtained by matching the
clustering and luminosity function of 2dFGRS, and can be an important
constraint in general on theories of galaxy formation, e.g., the
semi-analytical model. Combining the observed luminosity dependence of
clustering, our result implies that quite a fraction of faint galaxies are in
massive halos of galaxy clusters as the brightest ones, but most of the
$M_\star$ galaxies are in galactic halos.


title: The double main sequence of Omega Centauri

abstract:
  Recent, high precision photometry of Omega Centauri, the biggest Galactic
globular cluster, has been obtained with Hubble Space Telescope. The color
magnitude diagram reveals an unexpected bifurcation of colors in the main
sequence (MS). The newly found double MS, the multiple turnoffs and subgiant
branches, and other sequences discovered in the past along the red giant branch
of this cluster add up to a fascinating but frustrating puzzle. Among the
possible explanations for the blue main sequence an anomalous overabundance of
helium is suggested. The hypothesis will be tested with a set of FLAMES@VLT
data we have recently obtained (ESO DDT program), and with forthcoming ACS@HST
images.


title:
The pairwise velocity dispersion of galaxies: luminosity dependence and
  a new test of galaxy formation models

abstract:
  We present the first determination of the pairwise velocity dispersion (PVD)
for galaxies in different luminosity intervals using the final release of the
Two-Degree Field Galaxy Redshift Survey (2dFGRS). We have discovered quite
surprisingly that the relative velocities of the faint galaxies at small
separation are very high, around $700 \kms$, reaching similar values as the
brightest galaxies. At intermediate luminosities $M^*-1$ ($M^*$ is the
characteristic luminosity of the Schechter function), the relative velocities
exhibit a well defined steep minimum near $400 \kms$. This result has been
derived using a novel method to determine the real space power spectrum and the
PVD from the redshift space power spectrum of the 2dFGRS. Both quantities can
be determined quite reliably. We have taken the parameter $\beta$ equal to
0.45. But we have also checked that the results are changed very little, if we
allow a variation of $\beta$ with luminosity. The result is a challenge to the
current halo model of galaxies of Yang et al. that was obtained by matching the
clustering and luminosity function of the 2dFGRS, but cannot reproduce the
luminosity dependence of the PVD. It may also be an mportant constraint in
general on theories of galaxy formation, such as semi-analytical models and
hydro/N-body simulations of galaxy formation. Combined with the observed
luminosity dependence of clustering, our result implies that a substantial
fraction of faint galaxies, as well as the brightest ones, are in massive halos
of galaxy cluster size, but most of the $M^*$ galaxies are in galactic halos.


title:
Observational constraints on braneworld inflation: the effect of a
  Gauss-Bonnet term

abstract:
  High-energy modifications to general relativity introduce changes to the
perturbations generated during inflation, and the latest high-precision
cosmological data can be used to place constraints on such modified inflation
models. Recently it was shown that Randall-Sundrum type braneworld inflation
leads to tighter constraints on quadratic and quartic potentials than in
general relativity. We investigate how this changes with a Gauss-Bonnet
correction term, which can be motivated by string theory. Randall-Sundrum
models preserve the standard consistency relation between the tensor spectral
index and the tensor-to-scalar ratio. The Gauss-Bonnet term breaks this
relation, and also modifies the dynamics and perturbation amplitudes at high
energies. We find that the Gauss-Bonnet term tends to soften the
Randall-Sundrum constraints. The observational compatibility of the quadratic
potential is strongly improved. For a broad range of energy scales, the quartic
potential is rescued from marginal rejection. Steep inflation driven by an
exponential potential is excluded in the Randall-Sundrum case, but the
Gauss-Bonnet term leads to marginal compatibility for sufficient e-folds.


title: Quest for Fats: Roles for a Fat Dark Matter (WIMPZILLA)

abstract:
  Since 1990's the detection of extremely energetic air showers and precise
astronomical measurements have proved that our knowledge about fundamental laws
of Nature is far from being complete. These observations have found convincing
evidences against two popular believes: The spectrum of Cosmic Rays would have
a steep cutoff at energies around $10^{19}eV$ (GZK cutoff) and the
contravortial quantity called Cosmological Constant (dark energy) should be
strictly zero. They have been important additions to the yet unsolved mystery
of the nature of dark matter.For both phenomena many models have been
suggested. The top-down model decay of a Superheavy Dark Matter(SDM), also
called WIMPZILLA as the origin of the Ultra High Energy Cosmic Rays (UHECRs) -
is one of the most favorite candidates. Here we show that a meaningful
constraints on the mass, lifetime and cosmological contribution of SDM is
possible only if the energy dissipation of the remnants is precisely taken into
account. We discuss the simulation of relevant processes and their evolution in
the cosmological environment. We show that such a dark matter can be the
dominant component of Cold Dark Matter (CDM) with a relatively short lifetime.
Moreover, the equation of State of the Universe in this model fits the
Supernova type Ia data better than a stable dark matter. If a small fraction of
the mass of the SDM decays to an axion-like scalar field, its condensation can
also explain the dark energy without need for extreme fine tuning of the
parameters. Presumably, a meta-stable dark matter can explain 3 mysteries of
Physics and Cosmology. Finally we review some of the particle physics and
cosmological issues related to SDM and its associated quintessence field.


title: The Faint X-ray Source Population Near the 3C 295 cluster

abstract:
  We present a statistical analysis of the Chandra observation of the source
field around the 3C 295 galaxy cluster (z=0.46). Three different methods of
analysis, namely a chip by chip logN-logS, a two dimentional Kolmogorov-Smirnov
(KS) test, and the angular correlation function (ACF) show a strong overdensity
of sources in the North-East of the field, that may indicate a filament of the
large scale structure of the Universe toward 3C 295.


title: On Cross-correlating Weak Lensing Surveys

abstract:
  The present generation of weak lensing surveys will be superseded by surveys
run from space with much better sky coverage and high level of signal to noise
ratio, such as SNAP. However, removal of any systematics or noise will remain a
major cause of concern for any weak lensing survey. One of the best ways of
spotting any undetected source of systematic noise is to compare surveys which
probe the same part of the sky. In this paper we study various measures which
are useful in cross correlating weak lensing surveys with diverse survey
strategies. Using two different statistics - the shear components and the
aperture mass - we construct a class of estimators which encode such
cross-correlations. These techniques will also be useful in studies where the
entire source population from a specific survey can be divided into various
redshift bins to study cross correlations among them. We perform a detailed
study of the angular size dependence and redshift dependence of these
observables and of their sensitivity to the background cosmology. We find that
one-point and two-point statistics provide complementary tools which allow one
to constrain cosmological parameters and to obtain a simple estimate of the
noise of the survey.


title:
Microcanonical calculations of excess thermodynamic properties of dense
  binary systems

abstract:
  We derive a new formulation to calculate the excess chemical potential of a
fraction of $N_1$ particles interacting with $N_2$ particles of a different
species. The excess chemical potential is calculated numerically from first
principles by coupling molecular dynamics and Thomas-Fermi density functional
theory to take into account the contribution arising from the quantum electrons
on the forces acting on the ions. The choice of this simple functional is
motivated by the fact that the present paper is devoted to the derivation and
the validation of the method but more complicated functionals can and will be
implemented in the future. This new method is applied in the microcanonical
ensemble, the most natural ensemble for molecular dynamics simulations. This
avoids the introduction of a thermostat in the simulation, and thus uncontroled
modifications of the trajectories calculated from the forces between particles.
The calculations are conducted for three values of the input thermodynamic
quantities, energy and density, and for different total numbers of particles in
order to examine the uncertainties due to finite size effects. This method and
these calculations lie the basic foundation to study the thermodynamic
stability of dense mixtures, without any {\it a priori} assumption on the
degree of ionization of the different species.


title:
On self-similarity properties of isotropic turbulence in numerical
  simulations of the compressible Euler equations

abstract:
  We present numerical calculations of the parameters $C_{\nu}$, $C_{\epsilon}$
and $C_{\kappa}$ associated with the common closures for turbulence production,
dissipation and diffusion. In the case of homogeneous and isotropic turbulence,
these parameters are expected to be statistically scale-invariant within the
inertial subrange. In order to scrutinise this conjecture, we utilised a
generalisation of the Germano filtering formalism, which is applicable to
compressible flows as well. The filtering of data obtained from
three-dimensional direct numerical simulations of forced isotropic turbulence
with Mach numbers in the range $\sim 0.1...1$ then yielded values of the
closure parameters associated with different length scales. The results
indicate that the closure parameters are nearly universal for subsonic or
moderately transonic flows, although the resolution of $432^{3}$ grid cells in
our simulations is not quite sufficient to clearly establish scale invariance.
In addition, it was found that the customary assumption of a kinetic Prandtl
number of about unity for the gradient-diffusion closure is flawed due to the
misalignment between turbulent flux and the gradient of the turbulence energy.
Nevertheless, sound correlation can be achieved if the flux magnitude rather
than the flux vector is locally matched. This conclusion is particularly useful
for the family of subgrid scale models based on the turbulence energy equation.
Furthermore, the parameter of production $C_{\nu}$ was computed in the fashion
of dynamical procedures. Thereby, superior agreement between modelled and
explicitly evaluated turbulence stresses in comparison to the eddy-viscosity
closure with constant $C_{\nu}$ was verified.


title: Jets from Sub-Parsec to Kiloparsec Scales: A Physical Connection

abstract:
  The Chandra discovery of bright X-ray emission from kpc-scale jets allows
insight into the physical parameters of the jet flow at large scale. At the
opposite extreme, extensive studies of the inner relativistic jets in Blazars
with multiwavelength observations, yield comparable information on sub-parsec
scales. In the framework of simple radiation models for the emission regions we
compare the physical parameters of jets on these two very different scales in
the only two well studied Blazars for which large-scale emission has been
resolved by Chandra. Notably, we find that the relativistic Doppler factors and
powers derived independently at the two scales are consistent, suggesting that
the jet does not suffer severe deceleration or dissipation. Moreover the
internal equipartition pressures in the inner jet and in the external X-ray
bright knots scale inversely with the jet cross section as expected in the
simple picture of a freely expanding jet in equipartition.


title:
Relativistic Model of Detonation Transition from Neutron to Strange
  Matter

abstract:
  We study the conversion of neutron matter into strange matter as a detonation
wave. The detonation is assumed to originate from a central region in a
spherically symmetric background of neutrons with a varying radial density
distribution. We present self-similar solutions for the propagation of
detonation in static and collapsing backgrounds of neutron matter. The
solutions are obtained in the framework of general relativistic hydrodynamics,
and are relevant for the possible transition of neutron into strange stars.
Conditions for the formation of either bare or crusted strange stars are
discussed.


title: Scaling Laws in the Distribution of Galaxies

abstract:
  Research done during the previous century established our Standard
Cosmological Model. There are many details still to be filled in, but few would
seriously doubt the basic premise. Past surveys have revealed that the
large-scale distribution of galaxies in the Universe is far from random: it is
highly structured over a vast range of scales.
  To describe cosmic structures, we need to build mathematically quantifiable
descriptions of structure. Identifying where scaling laws apply and the nature
of those scaling laws is an important part of understanding which physical
mechanisms have been responsible for the organization of clusters,
superclusters of galaxies and the voids between them. Finding where these
scaling laws are broken is equally important since this indicates the
transition to different underlying physics.
  In describing scaling laws we are helped by making analogies with fractals:
mathematical constructs that can possess a wide variety of scaling properties.
We must beware, however, of saying that the Universe is a fractal on some range
of scales: it merely exhibits a specific kind of fractal-like behavior on those
scales. We exploit the richness of fractal scaling behavior merely as an
important supplement to the usual battery of statistical descriptors.
  We review the history of how we have learned about the structure of the
Universe and present the data and methodologies that are relevant to the
question of discovering and understanding any scaling properties that structure
may have. The ultimate goal is to have a complete understanding of how that
structure emerged. We are getting close!


title:
Ultrahigh Energy Cosmic Rays from Gamma Ray Bursts: Implications of the
  Recent Observational Results by Milagro

abstract:
  It has been speculated earlier that Gamma Ray Bursts are sources of ultrahigh
energy cosmic rays. Recently, the search for high energy photons from Gamma Ray
Bursts by Milagro group has put limits on the isotropic luminosity of these
transient sources in very high energy photons. The implications of the results
obtained by Milagro to our understanding of the ultrahigh energy cosmic ray
spectrum from these sources have been discussed in the present work.


title: Do Fermions and Bosons Produce the Same Gravitational Field?

abstract:
  We examine some cosmological consequences of gravity coupling with different
strength to fermions and bosons. We show that this leads to a different
perturbation of the standard picture of primordial nucleosynthesis than the
addition of extra neutrino types or overall scaling of the value of G. Observed
abundances of deuterium and helium-4 place bounds on the ratio of the bosonic
gravitational constant (G_B) to the fermionic gravitational constant (G_F) of
0.45 < G_B/G_F < 0.92 at 1-sigma, and 0.33 < G_B/G_F < 1.10 at 2-sigma. A value
of G_B < G_F can reconcile the current "tension" between the abundances of
deuterium and helium-4 predicted by primordial nucleosynthesis. We comment
briefly on other cosmological effects.


title:
Mid-Infrared and Submillimeter Observations of the Illuminating Source
  of McNeil's Variable Nebula

abstract:
  We present post-outburst observations of the mid-infrared spectrum and
submillimeter continuum of the illuminating source of the newly-discovered
McNeil's Nebula in the L1630 region of Orion. The 12 micron flux of this source
has increased by a factor of 25 after the outburst, whereas the submillimeter
continuum remains at its pre-outburst level. The bolometric luminosity has
increased by at least an order of magnitude, to ~34 L_sun, and is likely less
than 90 L_sun. The mid-infrared spectrum exhibits a strong and red continuum
with no emission or absorption features. The infrared slope of the spectral
energy distribution characterizes the illuminating source as a flat-spectrum
protostar, in both its active and quiescent states. New CO spectral line
observations show no evidence for a molecular outflow.


title: Radio Observations of Cluster Mergers

abstract:
  A very important aspect of the radio emission from galaxy clusters is
represented by the diffuse radio sources associated with the intracluster
medium: radio halos and relics. These radio sources indicate the existence of
large scale magnetic fields and of a population of relativistic electrons in
the cluster volume. The observational results provide evidence that these
phenomena are related to cluster merger activity, which supplies the energy to
the reacceleration of the radiating particles. The details of the halo-merger
connection are investigated through the comparison between the radio and the
X-ray emission.


title:
The NGC 7129 Young Stellar Cluster: A Combined Spitzer, MMT, and 2MASS
  Census of Disks, Protostars, and Outflows

abstract:
  We present the analysis of seven band (1.2 to 8 micron) ground and
space-based imaging of the NGC 7129 young stellar cluster from FLAMINGOS on
MMT, 2MASS, and the Infrared Array Camera (IRAC) on the Spitzer Space
Telescope. An analysis of the H-[4.5] vs. J-H colors reveals 84 objects with
circumstellar disks. Of these, 42 are located within the cluster core, a 0.5 pc
(100'') radius region of enhanced stellar surface density. From a luminosity
and extinction limited sample of the stars within the cluster core boundary we
have determined that 54% +/- 14% have circumstellar disks. Finally, we report
the detection of several resolved outflows in the IRAC 4.5 micron mosaic.


title:
High-resolution near-infrared speckle interferometry and radiative
  transfer modeling of the OH/IR star OH 104.9+2.4

abstract:
  We present near-infrared speckle interferometry of the OH/IR star OH
104.9+2.4 in the K' band obtained with the 6m telescope of the Special
Astrophysical Observatory (SAO). At a wavelength of lambda = 2.12 micron the
diffraction-limited resolution of 74 mas was attained. The reconstructed
visibility reveals a spherically symmetric, circumstellar dust shell (CDS)
surrounding the central star. The visibility function shows that the stellar
contribution to the total flux at lambda = 2.12 micron is less than ~50%,
indicating a rather large optical depth of the CDS. The azimuthally averaged
1-dimensional Gaussian visibility fit yields a diameter of 47 +/- 3mas (FHWM),
which corresponds to 112 +/- 13 AU for an adopted distance of D = 2.38 +/- 0.24
kpc. To determine the structure and the properties of the CDS of OH 104.9+2.4,
radiative transfer calculations using the code DUSTY were performed to
simultaneously model its visibility and the spectral energy distribution (SED).
We found that both the ISO spectrum and the visibility of OH 104.9+2.4 can be
well reproduced by a radiative transfer model with an effective temperature
T_eff = 2500 +/- 500 K of the central source, a dust temperature T_in = 1000
+/- 200 K at the inner shell boundary R_in = 9.1 R_star = 25.4 AU, an optical
depth tau = 6.5 +/- 0.3 at 2.2 micron, and dust grain radii ranging from a_min
= 0.005 +/- 0.003 micron to a_max = 0.2 +/- 0.02 micron with a power law with
index -3.5. It was found that even minor changes in a_max have a major impact
on both the slope and the curvature of the visibility function, while the SED
shows only minor changes. Our detailed analysis demonstrates the potential of
dust shell modeling constrained by both the SED and visibilities.


title: Structured jets in TeV BL Lac objects and radiogalaxies

abstract:
  TeV BL Lacertae objects require extreme relativistic bulk motion in the
gamma-ray emission region, but at the VLBI scale their radio knots hardly move.
The same sources show evidence, in radio, of a structure made of a fast spine
plus a slow layer. We propose that this structure exists even on the spatial
scale of regions responsible for the gamma-ray emission. One component sees the
(beamed) radiation produced by the other, and this enhances the inverse Compton
emission of both components. In addition, this allows the magnetic field to be
nearly in equipartition with the emitting particles. The inverse Compton
emission of the spine is anisotropic in its frame, possibly producing the
deceleration of the spine by the Compton rocket effect. In this scenario, also
the slow layer is a relatively strong high energy emitter, and thus
radiogalaxies become potentially detectable by GLAST.


title: A Chandra observation of the disturbed cluster core of Abell 2204

abstract:
  We present results from an observation of the luminous cluster of galaxies
Abell 2204 using the Chandra X-ray Observatory. We show the core of the cluster
has a complex morphological structure, made up of a high density core (n_e~0.2
cm^-3) with flat surface brightness, a surrounding central plateau, a tail-like
feature, wrapping around to the east, and an unusual radio source. A
temperature map and deprojected-profile shows that the temperature rises
steeply outside these regions, until around ~100 kpc where it drops, then rises
again. Abundance maps and profiles show that there is a corresponding increase
in abundance at the same radius as where the temperature drops. In addition
there are two cold fronts at radii of ~28 and 54.5 kpc. The disturbed
morphology indicates that the cluster core may have undergone a merger.
However, despite this disruption the mean radiative cooling time in the centre
is short (~230 Myr) and the morphology is regular on large scales.


title: The Cosmic Energy Inventory

abstract:
  We present an inventory of the cosmic mean densities of energy associated
with all the known states of matter and radiation at the present epoch. The
observational and theoretical bases for the inventory have become rich enough
to allow estimates with observational support for the densities of energy in
some 40 forms. The result is a global portrait of the effects of the physical
processes of cosmic evolution.


title: CMB anisotropies from primordial inhomogeneous magnetic fields

abstract:
  Primordial inhomogeneous magnetic fields of the right strength can leave a
signature on the CMB temperature anisotropy and polarization. Potentially
observable contributions to polarization B-modes are generated by vorticity and
gravitational waves sourced by the magnetic anisotropic stress. We compute the
corresponding CMB transfer functions in detail including the effect of
neutrinos. The shear rapidly causes the neutrino anisotropic stress to cancel
the stress from the magnetic field, suppressing the production of gravitational
waves and vorticity on super-horizon scales after neutrino decoupling. A
significant large scale signal from tensor modes can only be produced before
neutrino decoupling, and the actual amplitude is somewhat uncertain. Plausible
values suggest primordial nearly scale invariant fields of ~ 10^(-10)G today
may be observable from their large scale tensor anisotropy. They can be
distinguished from primordial gravitational waves by their non-Gaussianity.
Vector mode vorticity sources B-mode power on much smaller scales with a power
spectrum somewhat similar to that expected from weak lensing, suggesting
amplitudes ~ 10^(-9)G may be observable on small scales for a spectral index of
n ~ -2.9. In the appendix we review the covariant equations for computing the
vector and tensor CMB power spectra that we implement numerically.


title:
Grazing Incidence Optics for Wide-field X-ray Survey Imaging: A
  Comparison of Optimization Techniques

abstract:
  Utilizing a ray-tracing program, we have modeled the angular resolution of a
short focal length (~2m), large field-of-view (3.1 square degrees), grazing
incidence mirror shell. It has been previously shown in the literature that the
application of a polynomial to the surface of grazing incidence mirror shells
enhances the global performance of the mirror over the entire field-of-view.
The objective of this project was to efficiently locate the optimal polynomial
coefficients that would provide a 15 arcsec response over the entire
field-of-view. We have investigated various techniques for identifying the
optimal coefficients in a large multi-dimensional polynomial space. The
techniques investigated include the downhill simplex method, fractional
factorial, response surface (including Box-Behnken and central composite)
designs, artificial neural networks (such as back-propagation, general
regression, and group method of data handling neural networks), and the
Metropolis-Coupled Markov-Chain Monte-Carlo (MC-MCMC) method. We find of the
methods examined, the MC-MCMC approach performs the best. This project
demonstrates that the MC-MCMC technique is a powerful tool for designing
irreducible algorithms that optimize arbitrary, bounded functions and that it
is an efficient way of probing a multi-dimensional space and uncovering the
global minimum in a function that may have multiple minimums.


title:
Excitation of Molecular Material Near the Young Stellar Object
  LkHalpha-234 in NGC 7129

abstract:
  With the Spitzer-IRS we have obtained the first mid-IR spectroscopy of NGC
7129, in the unusually strong outflow and in a ridge of H_2 emission near the
Herbig Be star LkHalpha-234. The UV radiation field strength is estimated from
PAH band intensities in the H_2 ridge, and from the rotational H_2 emission
lines we have deduced aperture average excitation temperatures and column
densities in the two regions, finding the H_2 ridge values to be consistent
with pumping by UV fluorescence, but also comparable to regions that form H_2
in non-dissociative C-shocks. The H_2 emission in the outflow is consistent
with formation by collisional excitation in J-shocks, with shock velocities of
10 - 30 km/sec. A photodissociating component may be present in the outflow, by
similarity of S(0) line intensities in both regions. There is no indication of
warm dust in the outflow. We also present the first 16um imaging of a Galactic
nebula using the unique imaging capabilities of the IRS, and combine with
ground-based 2.12um (H_2 1-0 S(1)) imaging. Candidate pre-main sequence objects
are clearly evident in these data. We also find extended emission not
previously observed around the young B star BD+65 1638, ~22'' across, showing
that the region is not free of material as otherwise inferred by recent high
angular resolution mapping at submillimeter wavelengths. The presence of this
material complicates interpretation of the surrounding CO cavity and origin(s)
of the photodissociated region, and further spectroscopic observations are
needed to characterize its nature.


title: Observational Implications of Cosmological Event Horizons

abstract:
  In a universe dominated by a small cosmological constant or by eternal dark
energy with equation of state w < -1/3, observers are surrounded by event
horizons. The horizons limit how much of the universe the observers can ever
access. We argue that this implies a bound N~60 on the number of e-folds of
inflation that will ever be observable in our universe if the scale of the dark
energy today is ~(10^{-3} eV)^4. This bound is independent of how long
inflation lasted, or for how long we continue to observe the sky. The bound
arises because the imprints of the inflationary perturbations thermalize during
the late acceleration of the universe. They "inflate away" just like the
initial inhomogeneities during ordinary inflation. Thus the current CMB data
may be looking as far back in the history of the universe as will ever be
possible, making our era a most opportune time to study cosmology.


title: A GLIMPSE of Star Formation in the Giant H II Region RCW 49

abstract:
  GLIMPSE imaging using the Infrared Array Camera (IRAC) on the Spitzer Space
Telescope indicates that star formation is ongoing in the RCW 49 giant H II
region. A photometric comparison of the sources in RCW 49 to a similar area to
its north finds that at least 300 stars brighter than 13th magnitude in band
[3.6] have infrared excesses inconsistent with reddening due to foreground
extinction. These are likely young stellar objects (YSOs) more massive than 2.5
M_sun suggesting that thousands more low-mass stars are forming in this cloud.
Some of the YSOs are massive (B stars) and therefore very young, suggesting
that a new generation of star formation is occurring, possibly triggered by
stellar winds and shocks generated by the older (2-3 Myr) central massive
cluster. The Spitzer IRAC camera has proven to be ideally suited for
distinguishing young stars from field stars, and the GLIMPSE survey of the
Galactic Plane will likely find thousands of new star formation regions.


title: Deflagrations and Detonations in Thermonuclear Supernovae

abstract:
  We study a type Ia supernova explosion using three-dimensional numerical
simulations based on reactive fluid dynamics. We consider a delayed-detonation
model that assumes a deflagration-to-detonation transition. In contrast to the
pure deflagration model, the delayed-detonation model releases enough energy to
account for a healthy explosion, and does not leave carbon, oxygen, and
intermediate-mass elements in central parts of a white dwarf. This removes the
key disagreement between simulations and observations, and makes a delayed
detonation the mostly likely mechanism for type Ia supernovae.


title:
Resonant Excitation of White Dwarf Oscillations in Compact Object
  Binaries: 1. The No Back Reaction Approximation

abstract:
  We consider the evolution of white dwarfs with compact object companions
(specifically black holes with masses up to 10^6 solar masses, neutron stars,
and other white dwarfs). We suppose that the orbits are initially quite
elliptical and then shrink and circularise under the action of gravitational
radiation. During this evolution, the white dwarfs will pass through resonances
when harmonics of the orbital frequency match the stellar oscillation
eigenfrequencies. As a star passes through these resonances, the associated
modes will be excited and can be driven to amplitudes that are so large that
there is a back reaction on the orbit which, in turn, limits the growth of the
modes. A formalism is presented for describing this dynamical interaction for a
non-rotating star in the linear approximation when the orbit can be treated as
non-relativistic. A semi-analytical expression is found for computing the
resonant energy transfer as a function of stellar and orbital parameters for
the regime where back reaction may be neglected. This is used to calculate the
results of passage through a sequence of resonances for several hypothetical
systems. It is found that the amplitude of the l=m=2 f-mode can be driven into
the non-linear regime for appropriate initial conditions. We also discuss where
the no back reaction approximation is expected to fail, and the qualitative
effects of back reaction.


title:
Long-Lived Triaxiality in the Dynamically Old Elliptical Galaxy NGC
  4365: A Limit on Chaos and Black Hole Mass

abstract:
  Supermassive black holes in the centres of giant elliptical galaxies are
thought to induce chaos and eliminate triaxiality in their hosts. We address
whether this process operates in real systems, by modeling the stellar
kinematics of the old elliptical NGC 4365. This galaxy has a mean stellar
population age > 12 Gyr and is known for its kinematically decoupled core and
skew rotation at larger radii. We fit the two-dimensional mean velocity field
obtained by the SAURON integral-field spectrograph, and the isophotal
ellipticity and position-angle profiles, using the velocity field fitting
approach. We find NGC 4365 to be strongly triaxial (triaxiality parameter T
approximately 0.45) and somewhat flatter than it appears. Axisymmetry or near
axisymmetry (T < 0.1) is ruled out at > 95% confidence. In the most probable
orientation the long axis points roughly toward the observer, extending to the
southwest in projection. Strong triaxiality has persisted for hundreds of
dynamical times, ruling out black holes above 3 x 10^9 solar masses. The
M-sigma relation predicts 4 x 10^8 solar masses, which would not preclude
long-lived triaxiality and is consistent with the observations. NGC 4365 lends
support to a picture in which supermassive black holes, while omnipresent in
luminous giant elliptical galaxies, are not massive enough to alter their
global structure through chaos.


title:
MARCS-Model Stellar Atmospheres, and Their Application to the
  Photometric Calibration of the Spitzer-IRS

abstract:
  We describe state-of-the-art MARCS-code model atmospheres generated for a
group of A dwarf, G dwarf, and late-G to mid-K giant standard stars, selected
to photometrically calibrate the Spitzer-IRS, and compare the synthetic spectra
to observations of HR 6688, HR 6705, and HR 7891. The general calibration
processes and uncertainties are briefly described, and the differences between
various templated composite spectra of the standards are addressed. In
particular, a contrast between up-to-date model atmospheres and previously
published composite and synthetic spectra is illustrated for wavelength ranges
around 8um (where the SiO Delta(v) = 1 band occurs for the cooler standards)
and lambda greater than 20um, where the use of the Engelke function will lead
to increasingly large discrepancies due to the neglect of gravity in cool
stars. At this point, radiometric requirements are being met, absolute flux
calibration uncertainties (1-sigma) are ~20% in the SH and LH, and ~15% in the
SL and LL data, and order-to-order flux uncertainties are ~10% or less.
Iteration between the MARCS model atmosphere inputs and the data processing
will improve the S/N ratios and calibration accuracies.


title: Experimental Study of Acoustic Ultra-High-Energy Neutrino Detection

abstract:
  An existing array of underwater, large-bandwidth acoustic sensors has been
used to study the detection of ultra-high-energy neutrinos in cosmic rays.
Acoustic data from a subset of 7 hydrophones located at a depth of $\sim 1600$
m have been acquired for a total live time of 195 days. For the first time, a
large sample of acoustic background events has been studied for the purpose of
extracting signals from super-EeV showers. As a test of the technique, an upper
limit for the flux of ultra-high-energy neutrinos is presented along with
considerations relevant to the design of an acoustic array optimized for
neutrino detection.


title: Accretion in Brown Dwarfs: an Infrared View

abstract:
  This paper presents a study of the accretion properties of 19 very low mass
objects (Mstar .01-0.1 Msun) in the regions Chamaeleon I and rho-Oph For 8
objects we obtained high resolution Halpha profiles and determined mass
accretion rate Macc and accretion luminosity Lacc. Pabeta is detected in
emission in 7 of the 10 rho-Oph objects, but only in one in Cha I. Using
objects for which we have both a determination of Lacc from Halpha and a Pabeta
detection, we show that the correlation between the Pabeta luminosity and
luminosity Lacc, found by Muzerolle et al. (1998) for T Tauri stars in Taurus,
extends to objects with mass approx 0.03 Msun; L(Pab) can be used to measure
Lacc also in the substellar regime. The results were less conclusive for
Brgamma, which was detected only in 2 objects, neither of which had an Halpha
estimate of Macc. Using the relation between L(Pab) and Lacc we determined the
accretion rate for all the objects in our sample (including those with no
Halpha spectrum), more than doubling the number of substellar objects with
known Macc. When plotted as a function of the mass of the central object
together with data from the literature, our results confirm the trend of lower
Macc for lower Mstar, although with a large spread. Some of the spread is
probably due to an age effect; our very young objects in rho-Oph have on
average an accretion rate at least one order of magnitude higher than objects
of similar mass in older regions. As a side product, we found that the width of
Halpha measured at 10% peak intensity is not only a qualitative indicator of
accretion, but can be used to obtain a quantitative estimate of Macc over a
large mass range, from T Tauri stars to brown dwarfs. Finally, we found that
some of our objects show evidence of mass-loss.


title: Lensing Survey of the Most X-Ray Luminous Galaxy Clusters

abstract:
  We present the first three galaxy clusters of a larger sample of the most
X-ray luminous galaxy clusters selected from the ROSAT Bright Survey. This
project, which is a systematic search for strong lensing, aims at arc
statistics, mass determinations and studies of distant lensed galaxies.
  The three galaxy clusters presented here have been observed with the Wide
Field Imager at the ESO2.2m in the R- and V-band. The images show lensing
features like distinct distorted galaxies and arcs. Mass distributions of the
lensing galaxy clusters and photometric properties of some arc candidates are
presented. In addition we report the discovery of three giant arcs.


title: A low-mass stellar companion of the planet host star HD75289

abstract:
  We report on the detection of a new low-mass stellar companion of HD75289, a
G0V star that harbors one known radial-velocity planet (Udry et al. 2000).
Comparing an image of 2MASS with an image we obtained with SofI at the ESO
3.58m NTT three years later, we detected a co-moving companion located
21.465+-0.023arcsecs (621+-10AU at 29pc) east of HD75289. A second SofI image
taken 10 months later confirmed the common proper motion of HD75289B with its
host star. The infrared spectrum and colors of the companion are consistent
with an M2 to M5 main-sequence star at the distance of HD75289. No further
(sub)stellar companion down to H = 19mag could be detected. With the SofI
detection limit we can rule out additional stellar companions beyond 140AU and
substellar companions with masses m > 0.050Msun from 400AU up to 2000AU.


title: Evidence for Low-Dimensional Chaos in Semiregular Variable Stars

abstract:
  An analysis of the photometric observations of the light curves of the five
large amplitude, irregularly pulsating stars R UMi, RS Cyg, V CVn, UX Dra and
SX Her is presented. First, multi-periodicity is eliminated for these
pulsations, i.e. they are not caused by the excitation of a small number of
pulsation modes with constant amplitudes. Next, on the basis of energetics we
also eliminate stochasticity as a cause, leaving low dimensional chaos as the
only alternative. We then use a global flow reconstruction technique in an
attempt to extract quantitative information from the light curves, and to
uncover common physical features in this class of irregular variable stars that
straddle the RV Tau to the Mira variables. Evidence is presented that the
pulsational behavior of R UMi, RS Cyg, V CVn and UX Dra takes place in a
4-dimensional dynamical phase space, suggesting that two vibrational modes are
involved in the pulsation. A linear stability analysis of the fixed points of
the maps further indicates the existence of a two-mode resonance, similar to
the one we had uncovered earlier in R Sct: The irregular pulsations are the
result of a continual energy exchange between two strongly nonadiabatic modes,
a lower frequency pulsation mode and an overtone that are in a close 2:1
resonance. The evidence is particularly convincing for R UMi, RS Cyg and V CVn,
but much weaker for UX Dra. In contrast, the pulsations of SX Her appear to be
more complex and may require a 6D space.


title:
The pre-main sequence star HD 34282: A very short period delta
  Scuti-type pulsator

abstract:
  HD 34282 has been found to pulsate during a systematic search for short-term
photometric variability in Herbig Ae/Be stars with the goal of determining the
position and size of the pre-main sequence instability strip. Simultaneous
Stromgren photometry is used in the frequency analysis, yielding two
frequencies with values of nu1=79.5 and nu2=71.3 c/d. The light curve with the
largest amplitude is that of the u band. This behaviour, which is not common
for delta Scuti stars, is explained as pulsation in a high radial order in
stars near the blue edge of the instability strip. The main period, with a
value of 18.12 min, represents the shortest period observed so far for a delta
Scuti-type pulsator. A seismic modelling, including instability predictions and
rotation effects, has been attempted. It is found that both main sequence and
pre-main sequence models predict modes in the range of 56 to 82 c/d (between
648 and 949 microHz), corresponding to oscillations of radial order n from 6 to
8. The highest of the observed frequencies only becomes unstable for models of
low metallicity, in agreement with results from spectroscopic measurements.


title:
The ISOPHOT-MAMBO survey of 3CR radio sources: Further evidence for the
  unified schemes

abstract:
  We present the complete set of ISOPHOT observations of 3CR radio galaxies and
quasars, which are contained in the ISO Data Archive, providing 75 mid- and
far-infrared spectral energy distributions (SEDs) between 5 and 200 micron. For
28 sources they are supplemented with MAMBO 1.2 mm observations and for 15
sources with new submillimetre data from the SCUBA archive.
  We check the orientation-dependent unified scheme, in which the powerful FR2
narrow line galaxies are quasars viewed at high inclination, so that their
nuclei are hidden behind a dust torus intercepting the optical-ultraviolet AGN
radiation and reemitting it in the infrared. We find that (1) both the quasars
and the galaxies show a high mid- to far-infrared luminosity ratio typical for
powerful AGNs and (2) -- when matched in 178 MHz luminosity -- both show the
same ratio of isotropic far-infrared to isotropic 178 MHz lobe power.
Therefore, from our large sample investigated here we find strong evidence for
the orientation-dependent unification of the powerful FR2 galaxies with the
quasars.


abstract:
  We report the first detection of X-ray emission from a brown dwarf in the
Pleiades, the M7-type Roque 14, obtained using the EPIC detectors on
XMM-Newton. This is the first X-ray detection of a brown dwarf intermediate in
age between ~12 and ~320 Myr. The emission appears persistent, although we
cannot rule out flare-like behaviour with a decay time-scale > 4 ks. The
time-averaged X-ray luminosity of Lx = (3.3 +/- 0.8) x 10^{27} erg/s, and its
ratios with the bolometric (Lx/Lbol = 10^{-3.05}) and Halpha (Lx/LHa = 4.0)
luminosities suggest magnetic activity similar to that of active main-sequence
M dwarfs, such as the M7 old-disc star VB 8, though the suspected binary nature
of Roque 14 merits further attention. No emission is detected from four
proposed later-type Pleiades brown dwarfs, with upper limits to Lx in the range
2.1-3.8 x 10^{27} erg/s and to log(Lx/Lbol) in the range -3.10 to -2.91.


title:
Detailed chemical composition of the open cluster IC 4651: The iron
  peak, alpha elements, and Li

abstract:
  We present a detailed chemical analysis of 22 stars along the
colour-magnitude sequence of the intermediate-age (1.7 Gyr) open cluster IC
4651. We find for the cluster a well-defined Fe abundance of [Fe/H]= 0.10 +/-
0.03 (internal errors), with a reddening E(b-y)=0.091. We also derive
abundances for the alpha elements Mg, Si, Ti, and Ca and find a moderate
enhancement of the three former elements. Among the Fe group elements, Cr and
Ni are slightly overabundant ([X/Fe] ~ 0.05). The Na abundance among the giants
is more than 0.2 dex higher than in the dwarfs. We interpret this as due to
dredge-up of 23Na in the giants. Li abundances show a well-defined pattern: the
Solar-type stars have an almost constant Li abundance, just below that of the
Hyades, and the Li-dip is pronounced and well determined. Turnoff stars just
above the dip have a `cosmic' Li abundance, but within a very small range of
magnitudes (0.25 mag) higher on the turnoff, Li drops by more than a factor 10
implying that some extra mixing is required. Among the giants, two probable
clump stars show detectable Li, while all the other (likely) RGB stars do not.
We show that rotating stellar models including the most recent developments for
meridional circulation and turbulence by shear instabilities explain very well
the observed Li pattern. The possibility remains open that the giants
exhibiting the highest Li abundances are actual RGB bump stars which have just
been through the so-called "lithium flash".


title: Dark Matter and Dark Energy from the solution of the strong CP problem

abstract:
  The Peccei Quinn (PQ) solution of the strong CP problem requires the
existence of axions, which are a viable candidate for Dark Matter. Here we show
that, if the Nambu Goldstone potential of the PQ model is replaced by a
potential V(|\Phi|) admitting a tracker solution, the scalar field |\Phi| can
account for Dark Energy, while the phase of \Phi yields axion Dark Matter. Such
Dark Matter and Dark Energy turn out to be weakly coupled. If V is a SUGRA
potential, the model essentially depends on a single parameter, the energy
scale \Lambda. Once we set \Lambda \simeq 10^{10} GeV, at the quark--hadron
transition, |\Phi| naturally passes through values suitable to solve the strong
CP problem, later growing to values providing fair amounts of Dark Matter and
Dark Energy. In this model, the linear growth factor, from recombination to
now, is quite close to \LambdaCDM. The selected \Lambda value can be an
indication of the scale where the soft breaking of SUSY occurred.


title: The multi-scale dust formation in substellar atmospheres

abstract:
  Substellar atmospheres are observed to be irregularly variable for which the
formation of dust clouds is the most promising candidate explanation. The
atmospheric gas is convectively unstable and, last but not least, colliding
convective cells are seen as cause for a turbulent fluid field. Since dust
formation depends on the local properties of the fluid, turbulence influences
the dust formation process and may even allow the dust formation in an
initially dust-hostile gas. A regime-wise investigation of dust forming
substellar atmospheric situations reveals that the largest scales are
determined by the interplay between gravitational settling and convective
replenishment which results in a dust-stratified atmosphere. The regime of
small scales is determined by the interaction of turbulent fluctuations.
Resulting lane-like and curled dust distributions combine to larger and larger
structures. We compile necessary criteria for a subgrid model in the frame of
large scale simulations as result of our study on small scale turbulence in
dust forming gases.


title: Observational Properties of Jets in Active Galactic Nuclei

abstract:
  Parsec scale jet properties are shortly presented and discussed.
Observational data are used to derive constraints on the jet velocity and
orientation, the presence of velocity structures, and the connection between
the pc and kpc scale. Two peculiar sources with limb-brightened jets: 1144+35
and Mkn 501 are discussed in detail.


abstract:
  Spectroscopic surveys are undergoing a rapid expansion in their data
collecting capabilities, reaching the level of hundreds of spectra per
pointing. An efficient use of such huge amounts of information requires a high
degree of interconnection between the various tools involved in preparing the
observations, reducing the data, and carrying out the data analysis. DRAGO
(Data Reduction and Analysis Graphical Organizer) attempts to easy the process,
by integrating in a global framework the main data handling components: from
reduction pipelines, to data organization, plotting, and browsing tools, to
storing the data reduction results in a database for further analysis. DRAGO
allows the use of the astronomer own's preferred tools, by "plugging them in"
in an environment which handles transparently the communications between them.
See http://cosmos.mi.iasf.cnr.it/pandora .


title: Mie Scattering by Ensembles of Particles with Very Large Size Parameters

abstract:
  We present a computer program for the simulation of Mie scattering in case of
arbitrarily large size parameters. The elements of the scattering matrix,
efficiency factors as well as the corresponding cross sections, the albedo and
the scattering asymmetry parameter are calculated. Single particles as well as
particle ensembles consisting of several components and particle size
distributions can be considered.


title:
Star-to-star Na and O abundance variations along the red giant branch in
  NGC 2808

abstract:
  We report for the first time Na and O abundances from high-resolution, high
S/N echelle spectra of 20 red giants in NGC 2808, taken as part of the Science
Verification program of the FLAMES multi-object spectrograph at the ESO VLT. In
these stars, spanning about 3 mag from the red giant branch (RGB) tip, large
variations are detected in the abundances of oxygen and sodium, anticorrelated
with each other; this is a well known evidence of proton-capture reactions at
high temperatures in the ON and NeNa cycles. One star appears super O-poor; if
the extension of the Na-O anticorrelation is confirmed, NGC 2808 might reach O
depletion levels as large as those of M 13. This result confirms our previous
findings based on lower resolution spectra (Carretta et al. 2003) of a large
star-to-star scatter in proton capture elements at all positions along the RGB
in NGC 2808, with no significant evolutionary contribution. Finally, the
average metallicity for NGC 2808 is [Fe/H]= -1.14 +/- 0.01 dex (rms=0.06) from
19 stars.