title: On the properties of contact binary stars

abstract:
  A catalogue of light curve solutions of contact binary stars has been
compiled. It contains the results of 159 light curve solutions. Properties of
contact binary stars were studied by using the catalogue data.
  As it is well known since Lucy's (1968a,b) and Mochnacki's (1981) works,
primary components transfer their own energy to the secondary star via the
common envelope around the two stars. This transfer was parameterized by a
transfer parameter (ratio of the observed and intrinsic luminosities of the
primary star). We proved that this transfer parameter is a simple function of
the mass and luminosity ratio. This newly found relation is valid for all
systems except H type systems which have a different relation.
  We introduced a new type of contact binary stars: H subtype systems which
have a large mass ratio ($q>0.72$). These systems show highly different
behaviour on the luminosity ratio - transfer parameter diagram from other
systems and according to our results the energy transfer rate is less efficient
in them than in other type of contact binary stars. We also show that different
types of contact binaries have well defined locations on the mass ratio -
luminosity ratio diagram. All contact binary systems do not follow Lucy's
relation ($L_2/L_1 = (M_2/M_1)^{0.92}$). No strict mass ratio - luminosity
ratio relation of contact binary stars exists.


title: Direct Detection of Sub-stellar Companions with MIDI

abstract:
  Current detection methods of planetary companions do not allow retrieving
their spectral information properties. The method of Differential
Interferometry has the potential to complement such information by comparing
interferometric observables in various spectral channels. We outline the basic
aspects of this method and how it can soon be realised by the Mid-infrared
Interferometric instrument (MIDI) at the Very Large Telescope Interferometer
(VLTI) observatory. A set of possible candidates for such direct observation
has been selected among currently identified planetary companions. Differential
Interferometry with MIDI would be complementary to other ground-based programs.
The method may also be an alternative for future space-based planetary
spectroscopy.


title:
The shortest period M-dwarf eclipsing system BW3 V38, II: determination
  of absolute elements

abstract:
  The spectroscopic data for the short-period (0.1984 d)eclipsing binary V38,
discovered by the OGLE micro-lensing team in Baade's Window field BW3, are
analyzed. Radial velocity curves are derived from mid-resolution spectra
obtained with EMMI-NTT at ESO - La Silla, and a simultaneous solution of the
existing light curve by OGLE and of the new radial velocity curves is obtained.
The system is formed by almost twin M3e dwarf components that are very close,
but not yet in contact. The spectra of both dwarfs show signatures of the
presence of strong chromospheres. Spectroscopy definitely confirms, therefore,
what was suggested on the basis of photometry: BW3 V38 is indeed a unique
system, as no other similar binary with M components and in such a tight orbit
is known. Within the limits posed by the relatively large errors, due to the
combined effect of system faintness and of the constraints on exposure time,
the derived physical parameters seem to agree with the relations obtained from
the other few known eclipsing binaries with late type components (which
indicate a discrepancy between the available evolutionary models and the data
at ~ 10% level). A possible explanation is the presence of strong magnetic
fields and fast rotation (that applies to the BW3 V38 case as well). A simple
computation of the system secular evolution by angular momentum loss and spin
orbit synchronization shows that the evolution of a system with M dwarfs
components is rather slow, and indicates as well a possible reason why systems
similar to BW3 V38 are so rare.


title:
WIYN/Hydra Detection of Lithium Depletion in F Stars of the Young Open
  Cluster M35 and Implications for the Development of the Lithium Gap

abstract:
  We report discovery of significant depletion of Li on the surfaces of F dwarf
stars in the 150-Myr-old open cluster M35, analagous to a feature in the
700-Myr-old Hyades cluster that has been referred to as the ``Li gap.'' We have
caught the gap in the act of forming: using high resolution, high S/N,
WIYN/Hydra observations, we detect Li in all but a few M35 F stars; the maximum
depletion lies at least 0.6-0.8 dex below minimally depleted (or undepleted)
stars. The M35 Li depletion region, a) is quite wide, with clear depletion seen
from 6000K to 6700K or hotter; b) shows a significant dispersion in Li
abundance at all T_eff, even with stars of the same T_eff; and c) contains
undepleted stars (as well as depleted ones) in the (narrow) classical Hyades
gap region, which itself shows no undepleted stars. All of these M35 Li
depletion properties support rotationally-induced slow mixing as the primary
physical mechanism that forms the gap, and argues against other proposed
mechanisms, particularly diffusion and steady main sequence mass loss. When
viewed in the context of the M35 Li depletion properties, the Hyades Li gap may
well be wider than is usually recognized.


title:
Star-disc interactions in a galactic centre and oblateness of the inner
  stellar cluster

abstract:
  Structure of a quasi-stationary stellar cluster is modelled assuming that it
is embedded in the gravitational field of a super-massive black hole. Gradual
orbital decay of stellar trajectories is caused by the dissipative interaction
with an accretion disc. Gravitational field of the disc is constructed and its
effect on the cluster structure is taken into account as an axially symmetric
perturbation. Attention is focused on a circumnuclear region (r<10^4
gravitational radii) where the effects of the central black hole and the disc
dominate over the influence of an outer galaxy. It is shown how the stellar
system becomes gradually flattened towards the disc plane. For certain
combinations of the model parameters, a toroidal structure is formed by a
fraction of stars. Growing anisotropy of stellar velocities as well as their
segregation occur. The mass function of the inner cluster is modified and it
progressively departs from the asymptotic form assumed in the outer cluster. A
new stationary distribution can be characterized in terms of velocity
dispersion of the stellar sample in the central region of the modified cluster.


title: Diffusion and drift of cosmic rays in highly turbulent magnetic fields

abstract:
  We determine numerically the parallel, perpendicular, and antisymmetric
diffusion coefficients for charged particles propagating in highly turbulent
magnetic fields, by means of extensive Monte Carlo simulations. We propose
simple expressions, given in terms of a small set of fitting parameters, to
account for the diffusion coefficients as functions of magnetic rigidity and
turbulence level, and corresponding to different kinds of turbulence spectra.
The results obtained satisfy scaling relations, which make them useful for
describing the cosmic ray origin and transport in a variety of different
astrophysical environments.


title: Solar model with CNO revised abundances

abstract:
  Recent three-dimensional, NLTE analyses of the solar spectrum have shown a
significant reduction in the C, N, O and Ne abundances leading to a Z/X ratio
of the order of 0.0177. We have computed solar models with this new mixture in
the OPAL opacity tables. The present He abundance we find seems rather
consistent with the helioseismic value. However, the convective envelope is too
shallow, and diffusion, even if it reduces the discrepancy, is not able to give
the current value. We present some numerical experiments consisting in changing
the diffusion velocities and/or the value of opacity at the base of the
convective envelope.


title: Shapes and Alignments of Galaxy Cluster Halos

abstract:
  We present distribution functions and spatial correlations of the shapes of
dark matter halos derived from Hubble Volume simulations of a LambdaCDM
universe. We measure both position and velocity shapes within spheres
encompassing mean density 200 times the critical value, and calibrate small-N
systematic errors using Poisson realizations of isothermal spheres and higher
resolution simulations. For halos more massive than 3x10^{14} Msun/h, the shape
distribution function peaks at (minor/major, intermediate/major) axial ratios
of (0.64,0.76) in position, and is rounder in velocity, peaking at (0.72,0.82).
Halo shapes are rounder at lower mass and/or redshift; the mean minor axis
ratio in position follows <c/a>(M,z) = c_{15,0} [1-\alpha\ln(M/10^{15}Msun/h)]
(1+z)^{-\epsilon}, with c_{15,0}=0.631 \pm 0.001, \alpha=0.023 \pm 0.002 and
\epsilon=0.086 \pm 0.004. Position and velocity principal axes are well aligned
in direction, with median alignment angle $22^\circ$, and the axial ratios in
these spaces are correlated in magnitude. We investigate mark correlations of
halo pair orientations using two measures: a simple scalar product shows $\ge
1%$ alignment extending to $30 \hinv \mpc$ while a filamentary statistic
exhibits non-random alignment extending to scales $\sims 200 \hinv \mpc$, ten
times the sample two-point correlation length and well into the regime of
negative two-point correlation. Cluster shapes are unaffected by the
large-scale environment; the shape distribution of supercluster members is
consistent with that of the general population.


title:
Optical spectroscopy of flares from the black hole X-ray transient
  A0620-00 in quiescence

abstract:
  We present a time-resolved spectrophotometric study of the optical
variability in the quiescent soft X-ray transient A0620-00. Superimposed on the
double-humped continuum lightcurve are the well known flare events which last
tens of minutes. Some of the flare events that appear in the continuum
lightcurve are also present in the emission line lightcurves. From the Balmer
line flux and variations, we find that the persistent emission is optically
thin. During the flare event at phase 1.15 the Balmer decrement dropped
suggesting either a significant increase in temperature or that the flares are
more optically thick than the continuum. The data suggests that there are two
HI emitting regions, the accretion disc and the accretion stream/disc region,
with different Balmer decrements. The orbital modulation of H$\alpha$ with the
continuum suggests that the steeper decrement is most likely associated with
the stream/disc impact region. We construct Doppler images of the H$\alpha$ and
H$\beta$ emission lines. Apart from showing enhanced blurred emission at the
region where the stream impacts the accretion disc, the maps also show
significant extended structure from the opposite side of the disc. The trailed
spectra show characteristic S-wave features that can be interpreted in the
context of an eccentric accretion disc (abridged).


title: A Keck/Deimos Survey of Red Giant Branch Stars in the Outskirts of M31

abstract:
  We are using the DEIMOS multi-object spectrograph on the Keck II 10m
telescope to conduct a spectroscopic survey of red giant branch stars in the
outskirts of M31. To date, velocities have been obtained for most of the major
substructures in the halo as well as at several positions in the far outer disk
and inner halo. First results concerning the giant stellar stream and major
axis substructures are presented here.


title: An accelerated closed universe

abstract:
  We study a model in which a closed universe with dust and quintessence matter
components may look like an accelerated flat Friedmann-Robertson-Walker (FRW)
universe at low redshifts. Several quantities relevant to the model are
expressed in terms of observed density parameters, $\Omega_M$ and
$\Omega_{\Lambda}$, and of the associated density parameter $\Omega_Q$ related
to the quintessence scalar field $Q$.


title: The Influence of Reaction Rates on the Final p-Abundances

abstract:
  The astrophysical p-process is responsible for the origin of the proton rich
nuclei,which are heavier than iron. A huge network involving thousands of
reaction rates is necessary to calculate the final p-abundances. But not all
rates included in the network have a strong influence on the p-nuclei
abundances. The p-process was investigated using a full nuclear reaction
network for a type II supernovae explosion when the shock front passes through
the O/Ne layer. Calculations were done with a multi-layer model adopting the
seed of a pre-explosion evolution of a 25 mass star. In extensive simulations
we investigated the impact of single reaction rates on the final p-abundances.
The results are important for the strategy of future experiments in this field.


title: The Crab Nebula's Wisps in Radio and Optical

abstract:
  We present four new, high-resolution VLA radio images of the Crab nebula,
taken between 2001 Feb. and Apr. The radio images show systematic variability
in the Crab's radio emission throughout the region near the pulsar. The
principal geometry of the variable features is that of elliptical ripples very
similar to the optical wisps. The radio wisps are seen to move systematically
outward with projected speeds of up to 0.3c. Comparing the new radio images to
our earlier ones from 1998 and 2000, we show there are also more slowly moving
features somewhat farther away from the pulsar. In particular, there is a
prominent moving feature to the northwest of the pulsar which has a projected
speed of order 10,000 km/s. Striation is seen throughout the nebula, suggesting
the presence of wave-like disturbances propagating through the synchrotron
bubble. The radio images were taken simultaneously with HST optical
observations. Comparing the radio to the optical images, we find that the radio
wisps are sometimes displaced from the optical ones or have no optical
counterparts. We also find that some optical wisps in particular, the brightest
optical wisps near the pulsar, do not seem to have radio counterparts. In the
exterior of the nebula, by contrast, there is generally a good correspondence
between the radio and optical features.


title:
Excitation of large-scale inertial waves in a rotating inhomogeneous
  turbulence

abstract:
  A mechanism of excitation of the large-scale inertial waves in a rotating
inhomogeneous turbulence due to an excitation of a large-scale instability is
found. This instability is caused by a combined effect of the inhomogeneity of
the turbulence and the uniform mean rotation. The source of the large-scale
instability is the energy of the small-scale turbulence. We determined the
range of parameters at which the large-scale instability occurs, the growth
rate of the instability and the frequency of the generated large-scale inertial
waves. Geophysical and astrophysical applications of the obtained results are
discussed.


title: Multifrequency Strategies for the Identification of Gamma-Ray Sources

abstract:
  More than half the sources in the Third EGRET (3EG) catalog have no firmly
established counterparts at other wavelengths and are unidentified. Some of
these unidentified sources have remained a mystery since the first surveys of
the gamma-ray sky with the COS-B satellite. The unidentified sources generally
have large error circles, and finding counterparts has often been a challenging
job. A multiwavelength approach, using X-ray, optical, and radio data, is often
needed to understand the nature of these sources. This chapter reviews the
technique of identification of EGRET sources using multiwavelength studies of
the gamma-ray fields.


title: Gravitational lensing of the CMB by galaxy clusters

abstract:
  We adapt a non-linear filter proposed by Hu 2001 for detecting lensing of the
CMB by large-scale structures to recover surface-density profiles of galaxy
clusters from their localised, weak gravitational lensing effect on CMB fields.
Shifting the band-pass of the filter to smaller scales, and normalising it such
as to reproduce the convergence rather than the deflection angle, we find that
the mean density profile of a sample of 100 clusters can be recovered to better
than 10% from well within the scale radius to almost the virial radius. The
kinetic Sunyaev-Zel'dovich effect is shown to be a negligible source of error.
We test the filter applying it to data simulated using the characteristics of
the Atacama Cosmology Telescope (ACT), showing that it will be possible to
recover mean cluster profiles outside a radius of 1' corresponding to ACT's
angular resolution.


title: The 6.7 keV KALPHA complex of He-like iron in transient plasmas

abstract:
  Time dependent numerical simulations of the K ALPHA complex of Fe XXV are
carried out as a function of temperature/density/radiation field variations in
high-temperature astrophysical and laboratory plasmas. In addition to several
well known features, the transient and steady state spectra reveal the effects
due to (a) time-dependent thermal and non-thermal radiation fields, (b) photo
and collisional excitation and ionization, and (c) high densities, on the
`quartet' of principal w,x,y,z lines, and dielectronic satellites. The highly
detailed models show precisely how, assuming a temporal-temperature
correlation, the X-ray intensity varies between 6.6 - 6.7 keV and undergoes a
`spectral inversion' in the w and z line intensities, characterizing an
ionization or a recombination dominated plasma. The dielectronic satellite
intensities are the most temperature dependent features, but insensitive to
density variations, and significantly contribute to the K ALPHA complex for T <
6.7 keV leading to asymmetric profiles. The 6.7 keV K ALPHA complex should be a
potential diagnostic of X-ray flares in AGN, afterglows in gamma-ray bursts,
and other non-equilibrium sources with the high-resolution measurements
possible from the upcoming mission Astro-E2. It is also shown that high
electron densities attenuate the line intensities in simulations relevant to
laboratory plasmas, such as in inertial confinement fusion, laser, or magnetic
Z-pinch devices.


title:
Prospects for ACT: simulations, power spectrum, and non-Gaussian
  analysis

abstract:
  A new generation of instruments will reveal the microwave sky at high
resolution. We focus on one of these, the Atacama Cosmology Telescope, which
probes scales 1000<l<10000, where both primary and secondary anisotropies are
important. Including lensing, thermal and kinetic Sunyaev-Zeldovich (SZ)
effects, and extragalactic point sources, we simulate the telescope's
observations of the CMB in three channels, then extract the power spectra of
these components in a multifrequency analysis. We present results for various
cases, differing in assumed knowledge of the contaminating point sources. We
find that both radio and infrared point sources are important, but can be
effectively eliminated from the power spectrum given three (or more) channels
and a good understanding of their frequency dependence. However, improper
treatment of the scatter in the point source frequency dependence relation may
introduce a large systematic bias. Even if all thermal SZ and point source
effects are eliminated, the kinetic SZ effect remains and corrupts measurements
of the primordial slope and amplitude on small scales. We discuss the
non-Gaussianity of the one-point probability distribution function as a way to
constrain the kinetic SZ effect, and we develop a method for distinguishing
this effect from the CMB in a window where they overlap. This method provides
an independent constraint on the variance of the CMB in that window and is
complementary to the power spectrum analysis.


title: The Innermost Ejecta of Core Collapse Supernovae

abstract:
  We ensure successful explosions (of otherwise non-explosive models) by
enhancing the neutrino luminosity via reducing the neutrino scattering cross
sections or by increasing the heating efficiency via enhancing the neutrino
absorption cross sections in the heating region. Our investigations show that
the resulting electron fraction Ye in the innermost ejecta is close to 0.5, in
some areas even exceeding 0.5. We present the effects of the resulting values
for Ye on the nucleosynthesis yields of the innermost zones of core collapse
supernovae.


title: The Complex Cooling Core of Abell 2029: Radio and X-ray Interactions

abstract:
  We present an analysis of Chandra observations of the central regions of the
cooling flow cluster Abell 2029. We find a number of X-ray filaments in the
central 40 kpc, some of which appear to be associated with the currently active
central radio galaxy. The outer southern lobe of the steep-spectrum radio
source appears to be surrounded by a region of cool gas and is at least
partially surrounded by a bright X-ray rim similar to that seen around radio
sources in the cores of other cooling flow clusters. Spectroscopic fits show
that the overall cluster emission is best fitted by either a two temperature
gas (kT_high=7.47 keV, kT_low=0.11 keV), or a cooling flow model with gas
cooling over the same temperature range. This large range of temperatures (over
a factor of 50) is relatively unique to Abell 2029 and may suggest that this
system is a very young cooling flow where the gas has only recently started
cooling to low temperatures. The cooling flow model gives a mass deposition
rate of Mdot=56 +16/-21 Msun/yr. In general, the cluster emission is elongated
along a position angle of 22 degrees with an ellipticity of 0.26. The
distribution of the X-ray emission in the central region of the cluster is
asymmetric, however, with excess emission to the north-east and south-east
compared to the south-west and north-west, respectively. Fitting and
subtracting a smooth elliptical model from the X-ray data reveals a dipolar
spiral excess extending in a clockwise direction from the cluster core to radii
of ~150 kpc. We estimate a total mass of M_spiral ~6 x 10^12 Msun in the spiral
excess. The most likely origins of the excess are either stripping of gas from
a galaxy group or bare dark matter potential which has fallen into the cluster,
or sloshing motions in the cluster core induced by a past merger.


title:
Discovery of high-amplitude X-ray variability in the Seyfert-LINER
  transition galaxy NGC7589

abstract:
  We present the first result of a programme to search for large flux
variations in the X-ray sources of the XMM Serendipitous Survey compared to
previous ROSAT observations. An increase in X-ray flux by a factor >10 was
discovered from the nucleus of the galaxy NGC7589 on a timescale of less than 5
years. The 0.4-10keV XMM spectrum can be approximated by a power-law with
photon index of 1.7-1.8, though it seems to flatten above 5keV, suggesting a
possible complex model, such as partial covering or disc reflection. A
classification based on an analysis of its optical spectrum places NGC7589 in
the Seyfert region, but close to the Seyfert-LINER border-line on the AGN
diagnostic diagrams. We classify NGC7589 as either Seyfert1.9 or LINERI, in the
light of the detection of a broad H_alpha line, which makes NGC7589 an AGN in
the low-luminosity regime. We interpret the observed variability in terms of
either changes in covering factor of absorbing gas in the AGN, or variability
in the intrinsic X-ray luminosity. Should the latter be the case, the inferred
Eddington accretion rate increased from the radiatively inefficient accretion
dominated regime to a value close to the putative critical value, at which a
transition of the accretion mode is supposed to take place. This possibility
presents a new prospect of studying accretion physics in the central black
holes of external galaxies by direct observing changes of `spectral state', as
is common in stellar black hole binary systems.


title:
High-Redshift Extremely Red Objects in the HST Ultra Deep Field Revealed
  by the GOODS IRAC Observations

abstract:
  Using early data from the Infrared Array Camera (IRAC) on the Spitzer Space
Telescope, taken for the Great Observatories Origins Deep Survey (GOODS), we
identify and study objects that are well-detected at 3.6um, but are very faint
(and in some cases, invisible) in the Hubble Ultra Deep Field (HUDF) ACS and
NICMOS images and in very deep VLT Ks-band imaging. We select a sample of 17
objects with f_nu(3.6um)/f_nu(z_{850})>20. The analysis of their spectral
energy-distributions (SEDs) from 0.4 to 8.0um shows that the majority of these
objects cannot be satisfactorily explained without a well-evolved stellar
population. We find that most of them can be well fitted by a simple
two-component model, where the primary component represents a massive, old
population that dominates the strong IR emission, while the secondary component
represents a low amplitude, on-going star-formation process that accounts for
the weak optical fluxes. Their estimated photometric redshifts (z_p) range from
1.6 to 2.9, with the median at z_p=2.4. For the simple star formation histories
considered here, their corresponding stellar masses range from 0.1 to 1.6e11
M_sun for a Chabrier Initial Mass Function (IMF). Their median rest-frame
Ks-band absolute magnitude is -22.9 mag in AB system, or 1.5xL*(K) for
present--day elliptical galaxies. In the scenario of pure luminosity evolution,
such objects may be direct progenitors for at least 14 to 51% of the local
population of early--type galaxies. Due to the small cosmic volume of the HUDF,
however, this simple estimate could be affected by other effects such as cosmic
variance and the strong clustering of massive galaxies. A full analysis of the
entire GOODS area is now underway to assess such effects.


title: Spectroscopy of clusters in the ESO Distant Cluster Survey (EDisCS)

abstract:
  We present spectroscopic observations of galaxies in 4 clusters at z =
0.7-0.8 and in one cluster at z~0.5 obtained with the FORS2 spectrograph on the
VLT as part of the ESO Distant Cluster Survey (EDisCS), a photometric and
spectroscopic survey of 20 intermediate to high redshift clusters. We describe
our target selection, mask design, observation and data reduction procedures,
using these first 5 clusters to demonstrate how our strategies maximise the
number of cluster members for which we obtain spectroscopy. We present
catalogues containing positions, I-band magnitudes and spectroscopic redshifts
for galaxies in the fields of our 5 clusters. These contain 236 cluster
members, with the number of members per cluster ranging from 30 to 67. Our
spectroscopic success rate, i.e. the fraction of spectroscopic targets which
are cluster members, averages 50% and ranges from 30% to 75%. We use a robust
biweight estimator to measure cluster velocity dispersions from our
spectroscopic redshift samples. We also make a first assessment of substructure
within our clusters. The velocity dispersions range from 400 to 1100 km s-1.
Some of the redshift distributions are significantly non-Gaussian and we find
evidence for significant substructure in two clusters, one at z~0.79 and the
other at z~0.54. Both have velocity dispersions exceeding 1000 km s-1 but are
clearly not fully virialised; their velocity dispersions may thus be a poor
indicator of their masses. The properties of these first 5 EDisCS clusters span
a wide range in redshift, velocity dispersion, richness and substructure, but
are representative of the sample as a whole. Spectroscopy for the full dataset
will allow a comprehensive study of galaxy evolution as a function of cluster
environment and redshift.


title:
Quantitative interpretation of the rotation curves of spiral galaxies at
  redshifts z~0.7 and z~1

abstract:
  We present decompositions of the rotation curves of three spiral galaxies at
redshifts z~0.7 and 1 into contributions by their bulges, disks, and dark
halos, respectively. In order to set constraints on the degeneracy of the
decompositions we interpret the morphology of the spiral structures
quantitatively in the framework of density wave theory. Galaxy models
constrained in such a way show that the distant galaxies, which are much
younger than nearby galaxies, have very likely 'maximum disks', i.e. are
dominated in their inner parts by baryonic matter. We argue that current
theories of the cosmogony of galaxies must allow for these types of galaxies.


title: The outflowing disks of B[e] supergiants and unclassified B[e] stars

abstract:
  B[e] supergiants are known to possess outflowing cool disks but also some
unclassified B[e] stars show clear indications for the presence of a neutral
disk. We derive constraints on the disk mass loss rates, temperature
distributions and disk opening angles for the Small Magellanic Cloud B[e]
supergiant Hen S 18 and the unclassified galactic B[e] star Hen 2-90 by
modeling the line luminosities of the [OI] lines arising in their optical
spectrum. These lines are supposed to form in a hydrogen neutral disk. We find
disk mass fluxes of order 3.4 10^-4 g s^-1 cm^-2 and 5.5 10^{-1} g
s^{-1}cm^{-2} resulting in disk mass loss rates of 1.0 10^{-4} M_sun yr^{-1}
and 1.5 10^{-5} M_sun yr^{-1} for Hen S 18 and Hen 2-90, respectively.


title: Redshift Dependence of QSO Spectral Variability

abstract:
  We present a combined analysis of the optical spectral variability for two
samples of QSOs, 42 objects at $z<0.4$ monitored at the Wise Observatory
(Giveon et al 1999), plus 59 objects up to $z\sim 3$ in the field of the
Magellanic Clouds, detected and/or monitored within the MACHO Project database
(Geha et al 2003). Our analysis shows some increase of the observed spectral
variability as a function of redshift, with a large scatter. These data are
compared with a model based on the addition of flares of different temperatures
to a stationary quasar SED, taking into account also the intrinsic scatter of
the SEDs.


title: A Project for a New Echo-Mapping Campaign at Intermediate Redshift

abstract:
  AGN masses can be estimated by "single epoch" spectral measurements through a
mass-luminosity- linewidth relation calibrated by echo mapping measurements of
a reference sample of low redshift ($z < 0.3$) and low luminosity ($M_B > -26$)
AGNs. To analyze the possible dependence of this relation on luminosity we
selected a sample of bright, intermediate redhift ($z \sim 1$) objects and we
started a spectrophotometric monitoring campaign with a typical sampling time
of about one month. Variability observations of lines with shorter wavelength
than H$_\beta$ will also provide new information on the structure of the broad
line region. Cross-correlation analysis of continuum and line variations will
require years of monitoring. We present a preliminary analysis of the data
collected during the first year of observations and we discuss the adequacy of
the spectrophotometric accuracy attained and future prospects of this project.


title:
Nuclear Reaction Network for Primordial Nucleosynthesis: a detailed
  analysis of rates, uncertainties and light nuclei yields

abstract:
  We analyze in details the standard Primordial Nucleosynthesis scenario. In
particular we discuss the key theoretical issues which are involved in a
detailed prediction of light nuclide abundances, as the weak reaction rates,
neutrino decoupling and nuclear rate modeling. We also perform a new analysis
of available data on the main nuclear processes entering the nucleosynthesis
reaction network, with particular stress on their uncertainties as well as on
their role in determining the corresponding uncertainties on light nuclide
theoretical estimates. The current status of theoretical versus experimental
results for 2H, 3He, 4He and 7Li is then discussed using the determination of
the baryon density as obtained from Cosmic Microwave Background anisotropies.


title:
A Substantial Population of Red Galaxies at z > 2: Modeling of the
  Spectral Energy Distributions of an Extended Sample

abstract:
  We investigate the nature of the substantial population of high-z galaxies
with Js-Ks>2.3 discovered as part of our FIRES survey. This colour cut
efficiently isolates z>2 galaxies with red rest-frame optical colors ("Distant
Red Galaxies" or DRGs). We select objects in the 2.5'x2.5' HDF-South (HDF-S)
and 5'x5' field around the MS1054-03 cluster; the surface densities at Ks<21
are 1.6+-0.6 and 1.0+-0.2 arcmin^-2. We discuss the 34 DRGs at 2<z<3.5: 11 at
Ks<22.5 in HDF-S and 23 at Ks<21.7 in the MS1054-03 field. We analyze the SEDs
constructed from our deep near-infrared (NIR) and optical imaging from the ESO
VLT and HST. We develop diagnostics involving I-Js, Js-H, and H-Ks to argue
that the red NIR colors of DRGs cannot be attributed solely to extinction and
require for many an evolved stellar population with prominent Balmer/4000A
break. In the rest-frame, the optical colours of DRGs fall within the envelope
of normal nearby galaxies and the UV colours suggest a wide range in star
formation activity and/or extinction. This contrasts with the much bluer and
more uniform SEDs of Lyman break galaxies (LBGs). From evolutionary synthesis
models with constant star formation, solar metallicity, Salpeter IMF, and
Calzetti et al. extinction law, we derive for the HDF-S (MS1054-03 field) DRGs
median ages of 1.7(2.0) Gyr, A_V = 2.7(2.4) mag, stellar masses 0.8(1.6)x10^11
Msun, M/L_V = 1.2(2.3) Msun/LVsun, and SFR = 120(170) Msun/yr. Models assuming
declining SFRs with e-folding timescales of 10Myr-1Gyr generally imply younger
ages, lower A_V's and SFRs, but similar stellar masses within a factor of two.
Compared to LBGs at similar redshifts and rest-frame L_V's, DRGs are older,
more massive, and more obscured for any given star formation history.
[ABRIDGED]


title: Berkeley 29, the most distant old open cluster

abstract:
  We present CCD BVI photometry of the old open cluster Berkeley 29, located in
the anticentre direction. Using the synthetic Colour - Magnitude Diagrams
technique we estimate at the same time its age, reddening, distance, and
approximate metallicity using three types of stellar evolutionary tracks. The
best solutions give: age=3.4 or 3.7 Gyr, (m-M)_0 = 15.6 or 15.8 with E(B-V) =
0.13 or 0.10, and metallicity lower than solar (Z=0.006 or 0.004), depending on
the adopted stellar models. Using these derived values, Be 29 turns out to be
the most distant open cluster known, with Galactocentric distance R_GC= 21.4 to
22.6 kpc.
  Hence, Be 29 qualitatively follows both the age-metallicity relation and the
metal abundance gradient typical of Galactic disc objects. The cluster position
and radial velocity, however, appear to link Be 29 to the family of the Canis
Major debris.


title: Extrasolar Trojan Planets close to Habitable Zones

abstract:
  We investigate the stability regions of hypothetical terrestrial planets
around the Lagrangian equilibrium points L4 and L5 in some specific extrasolar
planetary systems. The problem of their stability can be treated in the
framework of the restricted three body problem where the host star and a
massive Jupiter-like planet are the primary bodies and the terrestrial planet
is regarded as being massless. From these theoretical investigations one cannot
determine the extension of the stable zones around the equilibrium points.
Using numerical experiments we determined their largeness for three test
systems chosen from the table of the know extrasolar planets, where a giant
planet is moving close to the so-called habitable zone around the host star in
low eccentric orbits. The results show the dependence of the size and structure
of this region, which shrinks significantly with the eccentricity of the known
gas giant.


title:
Curious Variables Experiment (CURVE). TT Bootis - superhump period
  change pattern confirmed

abstract:
  We report extensive multi-station photometry of TT Boo during its June 2004
superoutburst. The amplitude of the superoutburst was about 5.5 mag and its
length over 22 days. The star showed a small re-brightening starting around the
9th day of the superoutburst. During entire bright state we observed clear
superhumps with amplitudes from 0.07 to 0.26 mag and a mean period of Psh =
0.0779589(47) days (112.261 +/- 0.007 min). The period was not constant but
decreased at the beginning and the end of superoutburst yet increased in the
middle phase. We argue that the complicated shape of the O-C diagram is caused
by real period changes rather than by phase shifts. Combining the data from two
superoutbursts from 1989 and 2004 allowed us to trace the birth of the late
superhumps and we conclude that it is a rather quick process lasting about one
day.


title: Can we be tricked into thinking that w is less than -1?

abstract:
  Dark energy candidates for which the equation-of-state parameter w is less
than -1 violate the dominant energy condition, and are typically unstable. In
scalar-tensor theories of gravity, however, the expansion of the universe can
mimic the behavior of general relativity with w<-1 dark energy, without
violating any energy conditions. We examine whether this possibility is
phenomenologically viable by studying Brans-Dicke models and characterizing
both the naturalness of the models themselves, and additional observational
constraints from limits on the time-dependence of Newton's constant. We find
that only highly contrived models would lead observers to measure w<-1.


title:
Near-infrared K-band imaging of a sample of Ultra-Steep-Spectrum radio
  sources selected at 74 MHz

abstract:
  In this paper we present near-infrared K-band imaging of a sample of
ultra-steep spectrum (USS) radio sources selected at 74 MHz. The dual selection
criteria of low frequency and USS means that we should be sensitive to the
highest redshift (z > 5) radio galaxies. We have obtained $K-$band magnitudes
for all of the objects in our sample of 26 and discuss the properties of each.
  There is a pronounced bias in this sample towards fainter magnitudes and thus
higher redshifts when compared to complete unfiltered samples such as 7CRS
(Willott et al. 2002), implying that the steep-spectrum technique is still
viable at 74 MHz. However, there are more bright (K < 17) sources in the 74 MHz
sample than in a similar sample selected at 151 MHz, namely 6C*. This is
principally due to the additional selection criterion of a small angular size
for the radio sources in 6C*, four of the six sources in the 74 MHz USS sample
with K < 17 have angular sizes > 15 arcsec (the angular size cutoff of 6C*).
  We find that the distribution of K-band magnitudes from a sample selected at
74 MHz is statistically indistinguishable from the 6C* sample, when similar
angular size filtering is applied to the 74 MHz sample.


title:
Entrainment coefficient and effective mass for conduction neutrons in
  neutron star crust: II Macroscopic treatment

abstract:
  Phenomena such as pulsar frequency glitches are believed to be attributable
to differential rotation of a current of ``free'' superfluid neutrons at
densities above the ``drip'' threshold in the ionic crust of a neutron star.
Such relative flow is shown to be locally describable by adaption of a
canonical two fluid treatment that emphasizes the role of the momentum
covectors constructed by differentiation of action with respect to the
currents, with allowance for stratification whereby the ionic number current
may be conserved even when the ionic charge number Z is altered by beta
processes. It is demonstrated that the gauge freedom to make different choices
of the chemical basis determining which neutrons are counted as ``free'' does
not affect their ``superfluid'' momentum covector, which must locally have the
form of a gradient (though it does affect the ``normal'' momentum covector
characterising the protons and those neutrons that are considered to be
``confined'' in the nuclei). It is shown how the effect of ``entrainment''
(whereby the momentum directions deviate from those of the currents) is
controlled by the (gauge independent) mobility coefficient K, estimated in
recent microscopical quantum mechanical investigations, which suggest that the
corresponding (gauge dependent) ``effective mass'' m* of the free neutrons can
become very large in some layers. The relation between this treatment of the
crust layers and related work (using different definitions of ``effective
mass'') intended for the deeper core layers is discussed.


title:
Nuclear stellar discs in low-luminosity elliptical galaxies: NGC 4458
  and NGC 4478

abstract:
  We present the detection of nuclear stellar discs in the low-luminosity
elliptical galaxies NGC 4458 and NGC 4478, which are known to host a
kinematically-decoupled core. Using archival HST imaging, and available
absorption line-strength index data based on ground-based spectroscopy, we
investigate the photometric parameters and the properties of the stellar
populations of these central structures. Their scale length, h, and face-on
central surface brightness, mu_0^c, fit on mu_0^c-h relation for galaxy discs.
For NGC 4458 these parameters are typical for nuclear discs, while the same
quantities for NGC 4478 lie between those of nuclear discs and the discs of
discy ellipticals. We present Lick/IDS absorption line-strength measurements of
Hbeta, Mgb, <Fe> along the major and minor axes of the galaxies. We model these
data with simple stellar populations that account for the alpha/Fe
overabundance. The counter-rotating central disc of NGC 4458 is found to have
similar properties to the decoupled cores of bright ellipticals. This galaxy
has been found to be uniformly old despite being counter-rotating. In contrast,
the cold central disc of NGC 4478 is younger, richer in metals and less
overabundant than the main body of the galaxy. This points to a prolonged star
formation history, typical of an undisturbed disc-like, gas-rich (possibly
pre-enriched) structure.


title:
Deep Luminosity Functions of Old and Intermediate-Age Globular Clusters
  in NGC 1316: Evidence for Dynamical Evolution of Second-Generation Globular
  Clusters

abstract:
  The Advanced Camera for Surveys on board the Hubble Space Telescope has been
used to obtain deep high-resolution images of the giant early-type galaxy NGC
1316 which is an obvious merger remnant. These observations supersede previous,
shallower observations which revealed the presence of a population of
metal-rich globular clusters of intermediate age (~ 3 Gyr). We detect a total
of 1496 cluster candidates, almost 4 times as many as from the previous WFPC2
images. We confirm the bimodality of the color distribution of clusters, even
in V-I, with peak colors 0.93 and 1.06. The large number of detected clusters
allows us to evaluate the globular cluster luminosity functions as a function
of galactocentric radius. We find that the luminosity function of the inner 50%
of the intermediate-age, metal-rich (`red') population of clusters differs
markedly from that of the outer 50%. In particular, the luminosity function of
the inner 50% of the red clusters shows a clear flattening consistent with a
turnover that is about 1.0 mag fainter than the turnover of the blue clusters.
This constitutes the first direct evidence that metal-rich cluster populations
formed during major mergers of gas-rich galaxies can evolve dynamically
(through disruption processes) into the red, metal-rich cluster populations
that are ubiquitous in `normal' giant ellipticals.


title:
Directions of Outflows, Disks, Magnetic Fields, and Rotation of YSOs in
  Collapsing Molecular Cloud Cores

abstract:
  The collapse of slowly rotating molecular cloud cores threaded by magnetic
fields is investigated by high-resolution numerical simulation. Outflow
formation in the collapsing cloud cores is also followed. In the models
examined, the cloud core and parent cloud rotate rigidly and are initially
threaded by a uniform magnetic field. The simulations show that the cloud core
collapses along the magnetic field lines. The magnetic field in the dense
region of the cloud core rotates faster than that of the parent cloud as a
consequence of spin-up of the central region during the collapse. The cloud
core exhibits significant precession of the rotation axis, magnetic field, and
disk orientation, with precession highest in the models with low initial field
strength ($\lesssim 20 \mu {\rm G}$). Precession in models with initial fields
of $\sim 40 \mu {\rm G}$ is suppressed by strong magnetic braking. Magnetic
braking transfers angular momentum form the central region and acts more
strongly on the component of angular momentum oriented perpendicular to the
magnetic field. After the formation of an adiabatic core, outflow is ejected
along the local magnetic field lines. Strong magnetic braking associated with
the outflow causes the direction of angular momentum to converge with that of
the local magnetic field, resulting in the convergence of the local magnetic
field, angular momentum, outflow, and disk orientation by the outflow formation
phase. The magnetic field of a young star is inclined at an angle of no more
than $30^\circ$ from that of the parent cloud at initial field strengths of
$\sim 20 \mu {\rm G}$, while at an initial field strength of $\sim 40 \mu {\rm
G}$, the magnetic field of the young star is well aligned with that of the
parent cloud.


title:
Infrared and X-ray variability of the transient Anomalous X-ray Pulsar
  XTE J1810-197

abstract:
  We report on observations aimed at searching for flux variations from the
proposed IR counterpart of the Anomalous X-ray Pulsar XTE J1810-197. These
data, obtained in March 2004 with the adaptive optics camera NAOS-CONICA at the
ESO VLT, show that the candidate proposed by Israel et al. (2004) was fainter
by Delta H=0.7+/-0.2 and Delta Ks=0.5+/-0.1 with respect to October 2003,
confirming it as the IR counterpart of XTE J1810-197. We also report on an
XMM-Newton observation carried out the day before the VLT observations. The
0.5-10 keV absorbed flux of the source was 2.2x10^-11 erg/s/cm^2, which is less
by a factor of about two compared to the previous XMM-Newton observation on
September 2003. Therefore, we conclude that a similar flux decrease took place
in the X-ray and IR bands. We briefly discuss these results in the framework of
the proposed mechanism(s) responsible for the IR variable emission of Anomalous
X-ray Pulsars.


title: The reactions and ashes of thermonuclear explosions on neutron stars

abstract:
  This paper reports on the detailed rp-process reaction flow on an accreting
neutron star and the resulting ashes of a type I X-ray burst. It is obtained by
coupling a 298 isotope reaction network to a self-consistent one-dimensional
model calculation with a constant accretion rate of dM/dt=1.0e17g/s (0.09
Eddington).


title: Star count analysis of the interstellar matter in the region of L1251

abstract:
  We studied the ISM distribution in and around the star forming cloud L1251
with optical star counts. A careful calculation with a maximum likelihood based
statistical approach resulted in B,V,R,I extinction distributions from the star
count maps. A distance of 330+/-30 pc was derived. The extinction maps revealed
an elongated dense cloud with a bow shock at its eastern side. We estimated a
Mach number of M~2 for the bow shock. A variation of the apparent dust
properties is detected, i.e. the Rv=Av/E{B-V} total to selective extinction
ratio varies from 3 to 5.5, peaking at the densest part of L1251. The spatial
structure of the head of L1251 is well modelled with a Schuster-sphere (i.e.
n=5 polytropic sphere). The observed radial distribution of mass fits the model
with high accuracy out to 2.5pc distance from the assumed center. Unexpectedly,
the distribution of NH3 1.3 cm line widths is also well matched by the Schuster
solution even in the tail of the cloud. Since the elongated head-tail structure
of L1251 is far from the spherical symmetry the good fit of the linewidths in
the tail makes it reasonable to assume that the present cloud structure has
been formed by isothermal contraction.


title:
Of NBOs and kHz QPOs: a low-frequency modulation in resonant
  oscillations of relativistic accretion disks

abstract:
  The origin of quasi periodic modulations of flux in the kilohertz range (kHz
QPOs), observed in low-mass X-ray binaries, is usually assumed to be physically
distinct from that of the ``normal branch oscillations'' (NBOs) in the
Z-sources. We show that a low-frequency modulation of the kHz QPOs is a natural
consequence of the non-linear relativistic resonance suggested previously to
explain the properties of the high-frequency twin peaks. The theoretical
results discussed here are reminiscent of the 6 Hz variations of frequency and
amplitude of the kHz QPOs reported by Yu, van der Klis and Jonker (2001).


title:
Evolution of Chemistry and Molecular Line Profile during Protostellar
  Collapse

abstract:
  Understanding the chemical evolution in star-forming cores is a necessary
pre-condition to correctly assess physical conditions when using molecular
emission. We follow the evolution of chemistry and molecular line profiles
through the entire star formation process, including a self-consistent
treatment of dynamics, dust continuum radiative transfer, gas energetics,
chemistry, molecular excitation, and line radiative transfer. In particular,
the chemical code follows a gas parcel as it falls toward the center, passing
through regimes of density, dust temperature, and gas temperature that are
changing both because of the motion of the parcel and the evolving luminosity
of the central source. We combine a sequence of Bonnor-Ebert spheres and the
inside-out collapse model to describe dynamics from the pre-protostellar stage
to later stages. The overall structures of abundance profiles show complex
behavior that can be understood as interactions between freeze-out and
evaporation of molecules. We find that the presence or absence of gas-phase CO
has a tremendous effect on the less abundant species. In addition, the ambient
radiation field and the grain properties have important effects on the chemical
evolution, and the variations in abundance have strong effects on the predicted
emission line profiles. Multi-transition and multi-position ob servations are
necessary to constrain the parameters and interpret observations correctly in
terms of physical conditions. Good spatial and spectral resolution is also
important in distinguishing evolutionary stages.


title:
Parametric resonance as a model for QPO sources -- I. A general approach
  to multiple scales

abstract:
  In the resonance model, high-frequency quasi-periodic oscillations (QPOs) are
supposed to be a consequence of nonlinear resonance between modes of
oscillations occurring within the innermost parts of an accretion disk. Several
models with a prescribed mode--mode interaction were proposed in order to
explain the characteristic properties of the resonance in QPO sources. In this
paper, we examine nonlinear oscillations of a system having a quadratic
nonlinearity and we show that this case is particularly relevant for QPOs. We
present a very convenient way how to study internal resonances of a fully
general system using the method of multiple scales. Finally, we concentrate to
conservative systems and discuss their behavior near the 3:2 resonance.


title: Observing Cluster Galaxies and their Progenitors with JDEM

abstract:
  The Joint Dark Energy Mission (JDEM) is expected to have a field-of-view that
is several orders of magnitude larger than that of current instruments on the
Hubble Space Telescope, with only slightly reduced sensitivity and resolution.
This contribution gives a brief discussion of the impact that JDEM would have
on studies of galaxies in clusters at 0.5<z<2 and of the most massive galaxies
at higher redshift. Of particular importance is JDEMs unique wide-field near-IR
capability, enabling the selection and morphological study of high redshift
galaxies in the rest-frame optical rather than the rest-frame ultra-violet.


title: Accurate rest frequencies of methanol maser and dark cloud lines

abstract:
  We report accurate laboratory measurements of selected methanol transition
frequencies between 0.834 and 230 GHz in order to facilitate astronomical
velocity analyses. New data have been obtained between 10 and 27 GHz and
between 60 and 119 GHz. Emphasis has been put on known or potential
interstellar maser lines as well as on transitions suitable for the
investigation of cold dark clouds. Because of the narrow line widths (<0.5
kms-1) of maser lines and lines detected in dark molecular clouds, accurate
frequencies are needed for comparison of the velocities of different methanol
lines with each other as well as with lines from other species. In particular,
frequencies for a comprehensive set of transitions are given which, because of
their low level energies (< 20 cm-1 or 30 K) are potentially detectable in cold
clouds. Global Hamiltonian fits generally do not yet yield the required
accuracy. Additionally, we report transition frequencies for other lines that
may be used to test and to improve existing Hamiltonian models.


title: An apparently normal gamma-ray burst with an unusually low luminosity

abstract:
  Much of progress in gamma-ray bursts has come from the studies of distant
events (redshift z~1). The brightest GRBs are the most collimated events and
seen across the Universe due to their brilliance. It has long been suspected
that nearest (and most common) events have been missed because they are not so
collimated or under-energetic or both. Here we report soft gamma-ray
observations of GRB 031203, the nearest event to date (z=0.106). This event
with a duration of 40 s and peak energy of >190 keV appears to be a typical
long duration GRB. However, the isotropic gamma-ray energy <~10^50 erg, about
three orders of magnitude smaller than the cosmological population. This event
as well as the other nearby but somewhat controversial event GRB 980425 are
clear outliers for the much discussed isotropic-energy peak-energy relation and
luminosity spectral-lag relations. Radio calorimetry shows that both these
events are under-energetic explosions. We conclude that there does indeed exist
a large population of under-energetic events.


title: The sub-energetic GRB 031203 as a cosmic analogue to GRB 980425

abstract:
  Over the six years since the discovery of the gamma-ray burst GRB 980425,
associated with the nearby (distance, ~40 Mpc) supernova 1998bw, astronomers
have fiercely debated the nature of this event. Relative to bursts located at
cosmological distances, (redshift, z~1), GRB 980425 was under-luminous in
gamma-rays by three orders of magnitude. Radio calorimetry showed the explosion
was sub-energetic by a factor of 10. Here, we report observations of the radio
and X-ray afterglow of the recent z=0.105 GRB 031203 and demonstrate that it
too is sub-energetic. Our result, when taken together with the low gamma-ray
luminosity, suggest that GRB 031203 is the first cosmic analogue to GRB 980425.
We find no evidence that this event was a highly collimated explosion viewed
off-axis. Like GRB 980425, GRB 031203 appears to be an intrinsically
sub-energetic gamma-ray burst. Such sub-energetic events have faint afterglows.
Intensive follow-up of faint bursts with smooth gamma-ray light curves (common
to both GRBs 031203 and 980425) may enable us to reveal their expected large
population.


title: Redshift-Independent Distances to Type Ia Supernovae

abstract:
  We describe a procedure for accurately determining luminosity distances to
Type Ia supernovae (SNe Ia) without knowledge of redshift. This procedure,
which may be used as an extension of any of the various distance determination
methods currently in use, is based on marginalizing over redshift, removing the
requirement of knowing $z$ a priori. We demonstrate that the Hubble diagram
scatter of distances measured with this technique is approximately equal to
that of distances derived from conventional redshift-specific methods for a set
of 60 nearby SNe Ia. This indicates that accurate distances for cosmological
SNe Ia may be determined without the requirement of spectroscopic redshifts,
which are typically the limiting factor for the number of SNe that modern
surveys can collect. Removing this limitation would greatly increase the number
of SNe for which current and future SN surveys will be able to accurately
measure distance. The method may also be able to be used for high-$z$ SNe Ia to
determine cosmological density parameters without redshift information.


title:
Nuclear spirals in galaxies: gas response to asymmetric potential. I.
  Linear theory

abstract:
  Nuclear spirals can provide a wealth of information about the nuclear
potential in disc galaxies. They are unlikely to form in nuclei with solid-body
rotation, yet they are present in a majority of galactic centres. Their
morphology varies depending on whether a central massive black hole (MBH) is
present or absent in the galaxy. In this paper I consider predictions of the
linear theory for waves induced in gas by asymmetric gravitational potential,
which are applicable to the nuclear spirals observed in galaxies. Generation
and propagation of waves is governed by dynamical resonances, and inclusion of
a MBH can move or even create resonances, greatly altering the extent and shape
of the nuclear spiral. I will use predictions of the linear theory presented
here as a guideline when interpreting hydrodynamical models in the second paper
of this series. I also comment on modifications that self-gravity in gas
imposes on the induced waves.


title:
Obscured AGN and the X-ray, Optical and Far-Infrared Number Counts of
  AGN in the GOODS Fields

abstract:
  The deep X-ray, optical, and far-infrared fields that constitute GOODS are
sensitive to obscured AGN (N_H>10^{22} cm^{-2}) at the quasar epoch (z~2-3), as
well as to unobscured AGN as distant as z~7. Luminous X-ray emission is a sign
of accretion onto a supermassive black hole and thus reveals all but the most
heavily obscured AGN. We combine X-ray luminosity functions with appropriate
spectral energy distributions for AGN to model the X-ray, optical and
far-infrared flux distributions of the X-ray sources in the GOODS fields. A
simple model based on the unified paradigm for AGN, with ~3 times as many
obscured AGN as unobscured, successfully reproduces the z-band flux
distributions measured in the deep HST ACS observations on the GOODS North and
South fields. This model is also consistent with the observed spectroscopic and
photometric redshift distributions once selection effects are considered. The
previously reported discrepancy between observed spectroscopic redshift
distributions and the predictions of population synthesis models for the X-ray
background can be explained by bias against the most heavily obscured AGN
generated both by X-ray observations and the identification of sources via
optical spectroscopy. We predict the AGN number counts for Spitzer MIPS 24 um
and IRAC 3.6-8 um observations in the GOODS fields, which will verify whether
most AGN in the early Universe are obscured in the optical. Such AGN should be
very bright far-infrared sources and include some obscured AGN missed even by
X-ray observations.


title:
Nuclear spirals in galaxies: gas response to asymmetric potential. II.
  Hydrodynamical models

abstract:
  Nuclear spirals naturally form as a gas response to non-axisymmetry in the
galactic potential, even if the degree of this asymmetry is very small. Linear
wave theory well describes weak nuclear spirals, but spirals induced by
stronger asymmetries in the potential are clearly beyond the linear regime.
Hydrodynamical models indicate spiral shocks in this latter case that,
depending on how the spiral intersects the x2 orbits, either get damped,
leading to the formation of the nuclear ring, or get strengthened, and
propagate towards the galaxy centre. Central massive black hole of sufficient
mass can allow the spiral shocks to extend all the way to its immediate
vicinity, and to generate gas inflow up to 0.03 M_sun/yr, which coincides with
the accretion rates needed to power luminous local Active Galactic Nuclei.


title:
Chandra Constraints on the AGN Fraction and Star Formation Rate of Red
  z>~2 Galaxies in the FIRES MS1054-03 Field

abstract:
  Very deep near-infrared observations have recently uncovered a significant
population of red galaxies at redshifts z>2. These distant red galaxies (DRGs)
are efficiently selected by the criterion J-K>2.3. We use Chandra data to
examine the X-ray emission from DRGs in the 5'x5' FIRES MS1054-03 field. Two of
40 DRGs with K<22 are detected by Chandra, and we infer that ~5 % of DRGs host
active nuclei with L>1.2x10^43 ergs/s. This fraction is smaller than that
inferred from optical and near-IR spectroscopy, probably largely due to strong
spectroscopic selection biases. By stacking all undetected DRGs we find that
their average X-ray flux in the 0.5-8 keV band is ~4.6x10^-17 ergs/s/cm^2. The
detection is only significant in the soft and full energy bands. The mean
detection may result from star formation, the presence of low luminosity AGN,
or a combination of both. Assuming the detection is due exclusively to star
formation, we find an average instantaneous star formation rate of 214 +- 68
(random) +- 73 (systematic) solar masses per year, in excellent agreement with
previous results from spectral energy distribution fitting when constant star
formation histories are assumed. These results may imply that DRGs contribute
significantly to the cosmic star formation rate at z~2.5. However, the mean
X-ray flux strictly provides only an upper limit to the star formation rate due
to the uncertain contribution of low luminosity, possibly obscured AGNs.
Observations at other wavelengths are needed to provide independent estimates
of the star formation rate of DRGs.


title: Dark Energy from Wet Dark Fluid

abstract:
  We propose a new equation of state for the Dark Energy component of the
Universe. It is modeled on the equation of state $p=w(\rho-\rho_{*})$ which can
describe a liquid, for example water. We show that its energy density naturally
decomposes into a component that behaves as a cosmological constant and one
whose energy density scales as $a^{-3(1+w)}$, and fit the parameters specifying
the equation of state to the new SNIa data, as well as WMAP and 2dF data. We
find that reasonable values of the parameters can be found that give our model
the same $\chi^2$ as that of $\Lambda$CDM. A remarkable feature of the model is
that we can do all this with $w>0$.


title: Wide field imaging of distant clusters

abstract:
  Wide field imaging is key to understanding the build-up of distant clusters
and their galaxy population. By focusing on the so far unexplored outskirts of
clusters, where infalling galaxies first hit the cluster potential and the hot
intracluster medium, we can help separate cosmological field galaxy evolution
from that driven by environment. I present a selection of recent advancements
in this area, with particular emphasis on Hubble Space Telescope wide field
imaging, for its superior capability to deliver galaxy morphologies and precise
shear maps of distant clusters.


title:
Proton acceleration beyond 100 EeV by an oblique shock wave in the jet
  of 3C 273

abstract:
  We estimate the highest energy of proton diffusively accelerated by shock in
knot A1 of the jet in luminous nearby quasar 3C 273. Referring to the recent
polarization measurements using very long baseline interferometry (VLBI), we
consider the shock propagation across magnetic field lines, namely,
configuration of the oblique shock. For larger inclination of the field lines,
the effects of particle reflection at the shock front are more pronounced, to
significantly increase acceleration efficiency. The quasiperpendicular shock
turns out to be needed for safely achieving the proton acceleration to the
energy above 100 EeV (10^20 eV) in a parameter domain reflecting conceivable
energy restrictions.


title: The buried Balmer-edge signatures from quasars

abstract:
  In our previous paper, we have reported the detection of a Balmer edge
absorption feature in the polarized flux of one quasar (Ton 202). We have now
found similar Balmer edge features in the polarized flux of four more quasars
(4C09.72, 3C95, B2 1208+32, 3C323.1), and possibly a few more, out of 14 newly
observed with the VLT and Keck telescopes. In addition, we also re-observed Ton
202, but we did not detect such a dramatic feature, apparently due to
polarization variability (the two observations are one-year apart). The
polarization measurements of some quasars are affected by an interstellar
polarization in our Galaxy, but the measurements have been corrected for this
effect reasonably well.
  Since the broad emission lines are essentially unpolarized and the
polarization is confined only to the continuum in the five quasars including
Ton 202 in both epochs, the polarized flux is considered to originate interior
to the broad emission line region. The Balmer edge feature seen in the
polarized flux is most simply interpreted as an intrinsic spectral feature of
the quasar UV/optical continuum, or the ``Big Blue Bump'' emission. In this
case, the edge feature seen in absorption indeed indicates the thermal and
optically-thick nature of the continuum emitted. However, we also discuss other
possible interpretations.


title: Revealing AGN by Polarimetry

abstract:
  Polarimetric study in the UV and optical has been one of the keys to reveal
the structure and nature of active galactic nuclei (AGN). Combined with the
HST's high spatial resolution, it has directly confirmed the predicted
scattering geometry of ~100 pc scale and accurately located the hidden nuclear
position in some nearby active galaxies. Recently, we are using optical
spectropolarimetry to reveal the nature of the accretion flow in the central
engine of quasars. This is to use polarized light to de-contaminate the
spectrum and investigate the Balmer edge spectral feature, which is otherwise
buried under the strong emission from the outer region surrounding the central
engine.


title: The Proper Motion of Sgr A*: II. The Mass of Sgr A*

abstract:
  We report measurements with the VLBA of the position of Sgr A* with respect
to two extragalactic radio sources over a period of eight years. The apparent
proper motion of \sgrab relative to J1745-283 is 6.379 +/- 0.024 mas/y along a
position angle of 209.60 +/- 0.18 degrees, almost entirely in the plane of the
Galaxy. The effects of the orbit of the Sun around the Galactic center can
account for this motion, and the residual proper motion of Sgr A* perpendicular
to the plane of the Galaxy is -0.4 +/- 0.9 km/s. A maximum-likelihood analysis
of the motion expected for a massive object within the observed Galactic center
stellar cluster indicates that Sgr A* contains more than about 10% of the
approximately 4 x 10^6 Msun deduced from stellar orbits. The intrinsic size of
Sgr A*, as measured by several investigators, is less than 1 AU, and the
implied mass density of ~10^22 Msun/pc^3 is within about three orders of
magnitude of a comparable super-massive black hole within its Schwarzschild
radius. Our observations provide the first direct evidence that a compact
radiative source at the center of a galaxy contains of order 10^6 Msun and
provides overwhelming evidence that it is in the form of a super-massive black
hole. Finally, the existence of "intermediate mass" black holes more massive
than ~10^4 Msun between roughly 10^3 and 10^5 AU from Sgr A* are excluded.


title: Are beryllium abundances anomalous in stars with giant planets?

abstract:
  In this paper we present beryllium (Be) abundances in a large sample of 41
extra-solar planet host stars, and for 29 stars without any known
planetary-mass companion, spanning a large range of effective temperatures. The
Be abundances were derived through spectral synthesis done in standard Local
Thermodynamic Equilibrium, using spectra obtained with various instruments. The
results seem to confirm that overall, planet-host stars have ``normal'' Be
abundances, although a small, but not significant, difference might be present.
This result is discussed, and we show that this difference is probably not due
to any stellar ``pollution'' events. In other words, our results support the
idea that the high-metal content of planet-host stars has, overall, a
``primordial'' origin. However, we also find a small subset of planet-host
late-F and early-G dwarfs that might have higher than average Be abundances.
The reason for the offset is not clear, and might be related either to the
engulfment of planetary material, to galactic chemical evolution effects, or to
stellar-mass differences for stars of similar temperature.


title: Beryllium anomalies in solar-type field stars

abstract:
  We present a study of beryllium (Be) abundances in a large sample of field
solar-type dwarfs and sub-giants spanning a large range of effective
temperatures. The analysis shows that Be is severely depleted for F stars, as
expected by the light-element depletion models. However, we also show that
Beryllium abundances decrease with decreasing temperature for stars cooler than
$\sim$6000 K, a result that cannot be explained by current theoretical models
including rotational mixing, but that is, at least in part, expected from the
models that take into account internal wave physics. In particular, the light
element abundances of the coolest and youngest stars in our sample suggest that
Be, as well as lithium (Li), has already been burned early during their
evolution. Furthermore, we find strong evidence for the existence of a Be-gap
for solar-temperature stars. The analysis of Li and Be abundances in the
sub-giants of our sample also shows the presence of one case that has still
detectable amounts of Li, while Be is severely depleted. Finally, we compare
the derived Be abundances with Li abundances derived using the same set of
stellar parameters. This gives us the possibility to explore the temperatures
for which the onset of Li and Be depletion occurs.


title: The mass composition of cosmic rays above 10^17 eV

abstract:
  It is shown that our knowledge of the mass composition of cosmic rays is
deficient at all energies above 10^17 eV. Systematic differences between
different measurements are discussed and, in particular, it is argued that
there is no compelling evidence to support the common assumption that cosmic
rays of the highest energies are protons. Our knowledge of the mass needs to be
improved if we are to resolve uncertainties about the energy spectrum and
interpret data on the arrival direction distribution of cosmic rays.


title:
Color transformations and bolometric corrections for Galactic halo
  stars: alpha-enhanced vs scaled-solar results

abstract:
  We have performed the first extensive analysis of the impact of an
[alpha/Fe]>0 metal distribution on broadband colors in the parameter space
(surface gravity, effective temperature, metal content) covered by Galactic
globular cluster stars.A comparison of updated and homogeneous ATLAS9 UBVRIJHKL
synthetic photometry, for both alpha-enhanced and scaled-solar metal
distributions, has shown that it is impossible to reproduce alpha-enhanced
(B-V) and (U-B) color transformations with simple rescalings of the
scaled-solar ones. At [Fe/H]$\sim -$2.0 alpha-enhanced transformations are well
reproduced by scaled-solar ones with the same [Fe/H], but this good agreement
breaks down at [Fe/H] larger than about -1.6.As a general rule, (B-V) and (U-B)
alpha-enhanced colors are bluer than scaled-solar ones at either the same
[Fe/H] or [M/H], and the differences increase with increasing metallicity and
decreasing T_eff. A preliminary analysis of the contribution of the various
alpha elements to the stellar colors shows that the magnesium abundance (and to
lesser extent oxygen and silicon) is the main responsible for these
differences. On the contrary, the bolometric correction to the V band and more
infrared colors predicted by alpha-enhanced transformations are well reproduced
by scaled-solar results, due to their weak dependence on the metal content.Key
parameters like the Turn Off and Zero Age Horizontal Branch V magnitudes, as
well as the red Giant Branch tip I magnitude obtained from theoretical
isochrones are in general unaffected when using the appropriate alpha-enhanced
transformations in place of scaled-solar ones. We have also studied the effect
of boundary conditions obtained from appropriate alpha-enhanced model
atmospheres on the evolutionary tracks in the HR diagram.


title: Scaling Dark Energy

abstract:
  We investigate the possibility of a dark energy component that is scaling
with epochs. A phenomenological model is introduced whose energy density
depends on the redshift in such a way that a smooth transition among the three
dominant phases of the universe evolution (radiation era, matter domination,
asymptotic de Sitter state) is achieved. We use the WMAP cosmic microwave
background data and the luminosity distances of Type Ia Supernovae to test
whether this data can provide a signal for scaling.


title: Detection of He II 4686 in eta Carinae

abstract:
  We report the detection of the emission line He II 4686 A in eta Carinae. The
equivalent width of this line is ~100 mA along most of the 5.5-yr cycle and
jumps to ~900 mA just before phase 1.0, followed by a brief disappearance. The
similarity between the intensity variations of this line and of the X-ray light
curve is remarkable, suggesting that they are physically connected. We show
that the number of ionizing photons in the ultraviolet and soft X-rays,
expected to be emitted in the shock wave from the colliding winds, is of the
order of magnitude required to produce the He II emission via photoionization.
  The emission is clearly blueshifted when the line is strong. The radial
velocity of the line is generally -100 Km/s, decreases steadily just before the
event, and reaches -400 Km/s at ph = 1.001. At this point, the velocity
gradient suddenly changes sign, at the same time that the emission intensity
drops to nearly zero. Possible scenarios for explaining this emission are
briefly discussed. The timing of the peak of He II intensity is likely to be
associated to the periastron and may be a reliable fiduciary mark, important
for constraining the orbital parameters.


title: 'Swing Absorption' of fast magnetosonic waves in inhomogeneous media

abstract:
  The recently suggested swing interaction between fast magnetosonic and Alfven
waves (Zaqarashvili and Roberts 2002) is generalized to inhomogeneous media. We
show that the fast magnetosonic waves propagating across an applied non-uniform
magnetic field can parametrically amplify the Alfven waves propagating along
the field through the periodical variation of the Alfven speed. The resonant
Alfven waves have half the frequency and the perpendicular velocity
polarization of the fast waves. The wave lengths of the resonant waves have
different values across the magnetic field, due to the inhomogeneity in the
Alfven speed. Therefore, if the medium is bounded along the magnetic field,
then the harmonics of the Alfven waves, which satisfy the condition for onset
of a standing pattern, have stronger growth rates. In these regions the fast
magnetosonic waves can be strongly 'absorbed', their energy going in
transversal Alfven waves. We refer to this phenomenon as 'Swing Absorption'.
This mechanism can be of importance in various astrophysical situations.


title:
Structure in the polarized Galactic synchrotron emission, in particular
  `depolarization canals'

abstract:
  The polarized component of the diffuse radio synchrotron emission of our
Galaxy shows structure, which is apparently unrelated to the structure in total
intensity, on many scales. The structure in the polarized emission can be due
to several processes or mechanisms. Some of those are related to the
observational setup, such as beam depolarization -- the vector combination and
(partial) cancellation of polarization vectors within a synthesized beam --, or
the insensitivity of a synthesis telescope to structure on large scales, also
known as the 'missing short spacings problem'. Other causes for structure in
the polarization maps are intrinsic to the radiative transfer of the emission
in the warm ISM, which induces Faraday rotation and depolarization.
  We use data obtained with the Westerbork Synthesis Radio Telescope at 5
frequencies near 350 MHz to estimate the importance of the various mechanisms
in producing structure in the linearly polarized emission. In the two regions
studied here, which are both at positive latitudes in the second Galactic
quadrant, the effect of 'missing short spacings' is not important. The
properties of the narrow depolarization 'canals' that are observed in abundance
lead us to conclude that they are mostly due to beam depolarization, and that
they separate regions with different rotation measures. As beam depolarization
only creates structure on the scale of the synthesized beam, most of the
structure on larger scales must be due to depth depolarization. We do not
discuss that aspect of the observations here, but in a companion paper we
derive information about the properties of the ISM from the structure of the
polarized emission.


title:
On the Possible Correlation Between the Orbital Periods of Extra-solar
  Planets and the Metallicity of the Host Stars

abstract:
  We investigate a possible correlation between the orbital periods $P$ of the
extra-solar planet sample and the metallicity [Fe/H] of their parent stars.
Close-in planets, on a few-days orbits, are more likely to be found around
metal-rich stars. Simulations show that a weak correlation is present. This
correlation becomes stronger when only sigle stars with one detected planet are
considered. We discuss several potential sources of bias that might mimic the
correlation, and find they can be ruled out, but not with high significance. If
real, the absence of very short-period planets around the stellar sample with
[Fe/H] $< 0.0$ can be interpreted as evidence of a metallicity dependence of
the migration rates of giant planets during formation in the protoplanetary
disc. The observed $P-$[Fe/H] correlation can be falsified or confirmed by
conducting spectroscopic or astrometric surveys of metal-poor stars ([Fe/H] $<
-0.5$) in the field.


title: New Reference Galaxy Standards for HI Emission Observations

abstract:
  We have taken advantage of the improved baselines and higher sensitivity
available with the upgraded Arecibo 305m telescope to create a new HI spectral
line catalog of disk galaxies which can be used as a reference catalog for
anyone interested in 21-cm spectral line work. In all 108 galaxies were
observed, covering 24h of the sky at declinations between 0 < delta < 36
degrees and velocities between 0 - 25,000 km s-1. The majority of the galaxies
were observed at least two times on different nights to avoid problems with
RFI, baselines fluctuations, etc. Comparing our measured values with all those
available in the literature show that while large individual variations may
exist, the average differences between the measurements to be zero. In all we
have considerable confidence in our measurements, and the resultant catalog
should be extremely useful as a well defined reference catalog for anyone
interested in 21-cm spectral line work.


title:
The automated classification of astronomical lightcurves using Kohonen
  self-organising maps

abstract:
  We apply the technique of self-organising maps (Kohonen 1990) to the
automated classification of singly periodic astronomical lightcurves. We find
that our maps readily distinguish between lightcurve types in both synthetic
and real datasets, and that the resulting maps do not depend sensitively on the
chosen learning parameters. Automated data analysis techniques are likely to be
become increasingly important as the size of astronomical datasets continues to
increase, particularly with the advent of ultra-wide-field survey telescopes
such as WASP, RAPTOR and ASAS.


title: On the Secular Behavior of Irregular Satellites

abstract:
  Although analytical studies on the secular motion of the irregular satellites
have been published recently, these theories have not yet been satisfactorily
reconciled with the results of direct numerical integrations. These
discrepancies occur because in secular theories the disturbing function is
averaged over orbital motions, whereas instead one should take into account
some large periodic terms, most notably the so-called ``evection''. We
demonstrate that such terms can be incorporated into the Kozai formalism, and
that our synthetic approach produces much better agreement with results from
symplectic integrations. Using this method, we plot the locations of secular
resonances in the orbital-element space, and we note that the distribution of
irregular satellite clusters appears to be non-random. We find that the large
majority of irregular-satellite groups cluster close to the secular resonances,
with several objects having practically stationary pericenters. None of the
largest satellites belong to this class, so we argue that this dichotomy
implies that the smaller near-resonant satellites might have been captured
differently than the largest irregulars.


title:
Correspondence between the adhesion model and the velocity dispersion
  for the cosmological fluid

abstract:
  Basing our discussion on the Lagrangian description of hydrodynamics, we
studied the evolution of density fluctuation for nonlinear cosmological
dynamics. Adhesion approximation (AA) is known as a phenomenological model that
describes the nonlinear evolution of density fluctuation rather well and that
does not form a caustic. In addition to this model, we have benefited from
discussion of the relation between artificial viscosity in AA and velocity
dispersion. Moreover, we found it useful to regard whether the velocity
dispersion is isotropic produces effective `pressure' or viscosity terms. In
this paper, we analyze plane- and spherical-symmetric cases and compare AA with
Lagrangian models where pressure is given by a polytropic equation of state.
  From our analyses, the pressure model undergoes evolution similar to that of
AA until reaching a quasi-nonlinear regime. Compared with the results of a
numerical calculation, the linear approximation of the pressure model seems
rather good until a quasi-nonlinear regime develops. However, because of
oscillation arising from the Jeans instability, we could not produce a stable
nonlinear structure.


title: The theory of synchrotron emission from supernova remnants

abstract:
  The time-dependent nonlinear kinetic theory for cosmic ray (CR) acceleration
in supernova remnants (SNRs) is applied studying the properties of the
synchrotron emission from SNRs, in particular, the surface brightness-diameter
($\Sigma-D$) relation. Detailed numerical calculations are performed for the
expected range of the relevant physical parameters, namely the ambient density
and the supernova explosion energy. The magnetic field in SNRs is assumed to be
significantly amplified by the efficiently accelerating nuclear CR component.
Due to the growing number of accelerated CRs the expected SNR luminosity
increases during the free expansion phase, reaches a peak value at the
beginning of the Sedov phase and then decreases again, since in this stage the
overall CR number remains nearly constant, whereas the effective magnetic field
diminishes with time. The theoretically predicted brightness-diameter relation
in the radio range in the Sedov phase is close to $\Sigma_\mathrm{R}\propto
D^{-17/4}$. It fits the observational data in a very satisfactory way. The
observed spread of $\Sigma_\mathrm{R}$ at a given SNR size $D$ is the result of
the spread of supernova explosion energies and interstellar medium densities.


title:
The Parkes quarter-Jansky flat-spectrum sample 3. Space density and
  evolution of QSOs

abstract:
  We analyze the Parkes quarter-Jansky flat-spectrum sample of QSOs in terms of
space density, including the redshift distribution, the radio luminosity
function, and the evidence for a redshift cutoff. With regard to the luminosity
function, we note the strong evolution in space density from the present day to
epochs corresponding to redshifts ~ 1. We draw attention to a selection effect
due to spread in spectral shape that may have misled other investigators to
consider the apparent similarities in shape of luminosity functions in
different redshift shells as evidence for luminosity evolution. To examine the
evolution at redshifts beyond 3, we develop a model-independent method based on
the V_max test using each object to predict expectation densities beyond z=3.
With this we show that a diminution in space density at z > 3 is present at a
significance level >4 sigma. We identify a severe bias in such determinations
from using flux-density measurements at epochs significantly later than that of
the finding survey. The form of the diminution is estimated, and is shown to be
very similar to that found for QSOs selected in X-ray and optical wavebands.
The diminution is also compared with the current estimates of star-formation
evolution, with less conclusive results. In summary we suggest that the
reionization epoch is little influenced by powerful flat-spectrum QSOs, and
that dust obscuration does not play a major role in our view of the QSO
population selected at radio, optical or X-ray wavelengths.


title:
First XMM-Newton study of two Narrow-Line Seyfert 1 galaxies discovered
  in the Sloan Digital Sky Survey

abstract:
  The Early Data Release of the Sloan Digital Sky Survey (SDSS) contains 150
Narrow-Line Seyfert 1 (NLS1) galaxies, most of them previously unknown. We
present here the study of the X-ray emission from two of these active galaxies
(SDSS J030639.57+000343.2 and SDSS J141519.50-003021.6), based upon XMM-Newton
observations. The spectral and timing characteristics of the two sources are
presented and compared against the typical properties of known NLS1 galaxies.
We found that these two NLS1 are within the dispersion range of the typical
values of this class of AGN, although with some interesting features that
deserve further studies.


title:
Radio and near-infrared observations of the steep spectrum Galactic
  plane radio source WKB 0314+57.8

abstract:
  Radio and near-infared observations towards the steep spectrum Galactic plane
radio source WKB 0314+57.8 are presented, in order to clarify the nature of
this source. The radio observations include archival and survey data, together
with new Giant Metrewave Radio Telescope observations at 617 MHz. The
near-infrared observations are in the J and K bands, from the Gemini instrument
on the Shane 3-m telescope. The radio observations show that WKB 0314+57.8 is
extended, with an very steep spectrum (with flux density proportional to
frequency to -2.5 power between 40 MHz and 1.5 GHz). The colour--magnitude
diagram constructed from near-infrared observations of the field suggests the
presence of a z approx 0.08 galaxy cluster behind the Galactic plane, reddened
by about 6 magnitudes of visual extinction. Although the steep spectrum source
has no obvious identification, two other radio sources in the field covered by
the near-infrared observations have tentative identifications with galaxies.
These observations indicate that WKB 0314+57.8 is a relic source in a cluster
of galaxies, not a pulsar.


title: Radial truncations in stellar discs in galaxies

abstract:
  We discuss the possible origin of the radial truncations in stellar discs,
using measurements that we presented in an earlier paper (Kregel, van der Kruit
& de Grijs, 2002). A tentative correlation is found with the de-projected
face-on central surface brightness; lower surface brightness discs tend to have
a smaller truncation radius in units of scalelength. This and our earlier
finding that in smaller spirals the truncation tends to occur at a larger
number of scalelengths are best reproduced when the truncation is caused by a
constant gas density threshhold on star formation.


title: Late-type giant variables in NGC6522, LMC and SMC: How do they differ?

abstract:
  Complete samples of 2MASS stars in 3 fields of differing metallicities (and
possibly differing age distributions) have been extracted and cross-correlated
with MACHO and ISO data to determine their variability and mass-loss
properties. In each M_K histogram a fall-off in numbers is seen above the tip
of the RGB. The luminosity of the tip increases with metallicity as does the
average J-K at given M_K. The proportion of stars with high H-K increases at
lower metallicities. This results from the increasing proportion of C stars.
All 3 fields contain similar types of variables, mainly short-period, Mira-like
and double-period (having long and short periods). The proportion of variable
stars decreases at lower metallicities and the minimum period associated with a
given amplitude gets longer. Various trends are seen in the K, log P diagrams
of each field. The Magellanic Cloud fields largely resemble each other but the
Bulge field is noticeably different. The stars that follow the 'A' K,log P
relation in the Bulge hardly extend beyond the M giant tip and the other groups
also appear truncated in M_K relative to their Magellanic Cloud counterparts.
In the Clouds there are many stars with periods around 200-300d that follow the
'C' or Mira relation but have relatively small amplitudes. The mid-IR sample
detected by ISOCAM during the Magellanic Cloud Mini-Survey appears to be
reliable and complete for sources with M_K more luminous than -7 mag, i.e., for
those close to the top of the AGB. The various colour-colour and
colour-magnitude diagrams reflect the increasing dominance of C stars at low
metallicity. Mira magnitude vs log P relations exist up to at least 7 microns.
Mass-loss from longer-period and double-period SRVs occurs at similar rates in
each field, despite differences in metallicity.


title: Asteroseismology of Sun-like Stars - A Proposal

abstract:
  In the past decade, helioseismology has revolutionized our understanding of
the interior structure of the Sun. In the next decade, asteroseismology will
place this knowledge into context, by providing structural information for
dozens of pulsating stars across the H-R diagram. Solar-like oscillations have
already been detected from the ground in a few stars, and several current and
planned satellite missions will soon unleash a flood of stellar pulsation data.
Deriving reliable seismological constraints from these observations will
require a significant improvement to our current analysis methods. We are
adapting a computational method, based on a parallel genetic algorithm, to help
interpret forthcoming observations of Sun-like stars. This approach was
originally developed for white dwarfs and ultimately led to several interesting
tests of fundamental physics, including a key astrophysical nuclear reaction
rate and the theory of stellar crystallization. The impact of this method on
the analysis of pulsating white dwarfs suggests that seismological modeling of
Sun-like stars will also benefit from this approach.


title: Metallicities of 0.3<z<1.0 Galaxies in the GOODS-North Field

abstract:
  We measure nebular oxygen abundances for 204 emission-line galaxies with
redshifts 0.3<z<1.0 in the Great Observatories Origins Deep Survey North
(GOODS-N) field using spectra from the Team Keck Redshift Survey (TKRS). We
also provide an updated analytic prescription for estimating oxygen abundances
using the traditional strong emission line ratio, R_{23}, based on the
photoionization models of Kewley & Dopita (2003). We include an analytic
formula for very crude metallicity estimates using the [NII]6584/Halpha ratio.
Oxygen abundances for GOODS-N galaxies range from 8.2< 12+log(O/H)< 9.1
corresponding to metallicities between 0.3 and 2.5 times the solar value. This
sample of galaxies exhibits a correlation between rest-frame blue luminosity
and gas-phase metallicity (i.e., an L-Z relation), consistent with L-Z
correlations of previously-studied intermediate-redshift samples. The zero
point of the L-Z relation evolves with redshift in the sense that galaxies of a
given luminosity become more metal poor at higher redshift. Galaxies in
luminosity bins -18.5<M_B<-21.5 exhibit a decrease in average oxygen abundance
by 0.14\pm0.05 dex from z=0 to z=1. This rate of metal enrichment means that
28\pm0.07% of metals in local galaxies have been synthesized since z=1, in
reasonable agreement with the predictions based on published star formation
rate densities which show that ~38% of stars in the universe have formed during
the same interval. (Abridged)


title: The running-mass inflation model and WMAP

abstract:
  We consider the observational constraints on the running-mass inflationary
model, and in particular on the scale-dependence of the spectral index, from
the new Cosmic Microwave Background (CMB) anisotropy measurements performed by
WMAP and from new clustering data from the SLOAN survey. We find that the data
strongly constraints a significant positive scale-dependence of $n$, and we
translate the analysis into bounds on the physical parameters of the inflaton
potential. Looking deeper into specific types of interaction (gauge and Yukawa)
we find that the parameter space is significantly constrained by the new data,
but that the running mass model remains viable.


title: Reading the Spectra of the Most Peculiar Type Ia Supernova 2002cx

abstract:
  In spite of the apparent lack of Si II and S II features in its spectra, SN
2002cx was classified as a peculiar Type Ia supernova (SN Ia) on the basis of
its overall photometric and spectroscopic behavior. Spectra obtained near
maximum light contained Fe III features, as in SN 1991T-like events, but the
blueshifts of the Fe III absorptions were exceptionally low. The luminosity
also was low. We use the supernova synthetic--spectrum code SYNOW to study line
identifications in SN 2002cx. We find that the maximum-light spectra appear to
contain weak features of Si II, S II, Si III, and Ca II, which strengthens the
connection with SN 1991T-like events. We show that later spectra, obtained 12,
25, and 56 days after maximum, consist of P-Cygni resonance-scattering features
due to permitted Fe II and Co II lines. SN 2002cx had been thought to have made
the transition from a permitted-line to a forbidden-line spectrum between 25
and 56 days. Owing to the low expansion velocities the postmaximum spectral
features are narrower and easier to identify than they are in other SNe Ia. SN
2002cx will lead to improved line identifications in other SNe Ia and clarify
when the transition from a permitted-line to a forbidden-line spectrum occurs.
In the context of current SN Ia explosion models, we suggest that the
properties of SN 2002cx may be consistent with 3D deflagration models, which
are not favored for normal SNe Ia.


title:
The Brera Multi-scale Wavelet HRI Cluster Survey: I Selection of the
  Sample and Number Counts

abstract:
  We describe the construction of the Brera Multi-scale Wavelet (BMW) HRI
Cluster Survey, a deep sample of serendipitous X-ray selected clusters of
galaxies based on the ROSAT HRI archive. This is the first cluster catalog
exploiting the high angular resolution of this instrument. Cluster candidates
are selected on the basis of their X-ray extension only, a parameter which is
well measured by the BMW wavelet detection algorithm. The survey includes 154
candidates over a total solid angle of ~160 deg2 at 10^{-12}erg s^{-1} cm^{-2}
and ~80 deg^2 at 1.8*10^{-13} erg s^{-1}$ cm^{-2}. At the same time, a fairly
good sky coverage in the faintest flux bins (3-5*10^{-14}erg s^{-1} cm^{-2})
gives this survey the capability to detect a few clusters with z\sim 1-1.2,
depending on evolution. We present the results of extensive Monte Carlo
simulations, providing a complete statistical characterization of the survey
selection function and contamination level. We also present a new estimate of
the surface density of clusters of galaxies down to a flux of 3*10^{-14}erg
s^{-1} cm^{-2}, which is consistent with previous measurements from PSPC-based
samples. Several clusters with redshifts up to z=0.92 have already been
confirmed, either by cross-correlation with existing PSPC surveys or from early
results of an ongoing follow-up campaign. Overall, these results indicate that
the excellent HRI PSF (5 arcsec ~FWHM on axis) more than compensates for the
negative effect of the higher instrumental background on the detection of
high-redshift clusters. In addition, it allows us to detect compact clusters
that could be lost at lower resolution, thus potentially providing an important
new insight into cluster evolution.


title: Disk Galaxy Rotation Curves in Triaxial CDM Halos

abstract:
  We use N-body hydrodynamical simulations to study the structure of disks in
triaxial potentials resembling CDM halos. Our analysis focuses on the accuracy
of the dark mass distribution inferred from rotation curves derived from
simulated long-slit spectra. We consider a massless disk embedded in a halo
with axis ratios of 0.5:0.6:1.0 and with its rotation axis aligned with the
minor axis of the halo. Closed orbits for the gaseous particles deviate from
coplanar circular symmetry, resulting in a variety of long-slit rotation curve
shapes, depending on the orientation of the disk relative to the line of sight.
Rotation curves may thus differ significantly from the spherically-averaged
circular velocity profile of the dark matter halo. "Solid-body" rotation
curves--typically interpreted as a signature of a constant density core in the
dark matter distribution--are obtained about 25% of the time for random
orientations although the dark matter follows the cuspy density profile
proposed by Navarro, Frenk & White (NFW). We conclude that the discrepancies
reported between the shape of the rotation curve of low surface brightness
galaxies and the structure of CDM halos may be resolved once the complex
effects of halo triaxiality on the dynamics of the gas component is properly
taken into account.