title: The ionization structure of early-B supergiant winds

abstract:
  We present empirically determined ionization conditions for the winds of 106
luminous B0 to B5 stars observed by IUE. The UV wind lines are modelled to
extract products of mass-loss rates (Mdot) times ionization fractions (Mdot
q_i(w), where w = v/v_infty) for N V, C IV, Si IV, Si III, Al III and C II. We
describe the general behaviour of the Mdot q_i(w) and their ratios,
demonstrating that the wind ionization increases with distance from the star,
contrary to recent findings for O star winds. Using empirical mass-loss rates
(from H alpha observations) and model prescriptions, we derive mean q_i(w)
values integrated over the wind, <q_i>. These <q_i> are quite small, never
exceeding 15% for Al III or 2% for Si IV. This is surprising, since the <q_i>
for these ions clearly peak within the observed spectral range. We conclude
that the low <q_i> arise because the <Mdot q_i> are underestimated by the wind
models, which assume that the outflows are smooth when they are, in fact,
highly structured.


title: Possible AGN Shock Heating in the Cool Core Galaxy Cluster Abell 478

abstract:
  We present a detailed X-ray study of the intracluster medium (ICM) of the
nearby, cool-core galaxy cluster Abell 478, with Chandra and XMM observations.
Using a wavelet smoothing hardness analysis, we derive detailed temperature
maps of A478, revealing a surprising amount of temperature structure. The broad
band Chandra spectral fits yield temperatures which are significantly hotter
than those from XMM, but the Fe ionization temperature shows good agreement. We
show that the temperature discrepancy is slightly reduced when comparing
spectra from regions selected to enclose nearly isothermal gas. However, by
simulating multi-temperature spectra and fitting them with a single temperature
model, we find no significant difference between Chandra and XMM, indicating
that non-isothermality cannot fully explain the discrepancy. We have discovered
4 hot spots located between 30--50 kpc from the cluster center, where the gas
temperature is roughly a factor of 2 higher than in the surrounding material.
We estimate the combined excess thermal energy present in these hot spots to be
(3+/-1)x10^59 erg. The location of and amount of excess energy present in the
hot spots are suggestive of a common origin within the cluster core, which
hosts an active galactic nucleus. This cluster also possesses a pair of X-ray
cavities coincident with weak radio lobes, as reported in a previous analysis,
with an associated energy <10% of the thermal excess in the hot spots. The
presence of these hot spots could indicate strong-shock heating of the ICM from
the central radio source -- one of the first such detections in a cool core
cluster. We also probe the mass distribution in the core and find it to be
characterized by a logarithmic slope of -0.35+/-0.22, which is significantly
flatter than an NFW cusp of -1. (abridged)


title:
The Influence of an Ambient Magnetic Field on Relativistic Collisionless
  Plasma Shocks

abstract:
  Plasma outflows from gamma-ray bursts, supernovae, and relativistic jets, in
general, interact with the surrounding medium through collisionless shocks. The
microphysics of such shocks are still poorly understood, which, potentially,
can introduce uncertainties in the interpretation of observations. It is now
well established that the Weibel two-stream instability is capable of
generating strong electromagnetic fields in the transition region between the
jet and the ambient plasma. However, the parameter space of collisionless
shocks is vast and still remains unexplored. In this Letter, we focus on how an
ambient magnetic field affects the evolution of the electron Weibel instability
and the associated shock. Using a particle-in-cell code, we have performed
three-dimensional numerical experiments on such shocks. We compare simulations
in which a jet is injected into an unmagnetized plasma with simulations in
which the jet is injected into a plasma with an ambient magnetic field both
parallel and perpendicular to the jet flow. We find that there exists a
threshold of the magnetic field strength below which the Weibel two-stream
instability dominates, and we note that the interstellar medium magnetic field
strength lies well below this value. In the case of a strong magnetic field
parallel to the jet, the Weibel instability is quenched. In the strong
perpendicular case, ambient and jet electrons are strongly accelerated because
of the charge separation between deflected jet electrons and less deflected jet
ions. Also, the electromagnetic topologies become highly non-linear and complex
with the appearance of anti-parallel field configurations.


title:
Formation and evolution of the Magellanic Clouds. I.Origin of
  structural, kinematical, and chemical properties of the Large Magellanic
  Cloud

abstract:
  We investigate the dynamical and chemical evolution of the Large Magellanic
Cloud (LMC) interacting with the Galaxy and the Small Magellanic Cloud (SMC)
based on a series of self-consistent chemodynamical simulations. Our numerical
models are aimed at explaining the entire properties of the LMC, i.e., the
observed structure and kinematics of its stellar halo and disk components as
well as the populations of the field stars and star clusters. The main results
of the present simulations are summarized as follows. (1) Tidal interaction
between the Clouds and the Galaxy during the last 9 Gyr transforms the
initially thin, non-barred LMC disk into the three different components: the
central bar, thick disk, and kinematically hot stellar halo. The central bar is
composed both of old field stars and newly formed ones with each fraction being
equal in its innermost part. The final thick disk has the central velocity
dispersion of $\sim$ 30 km s$^{-1}$ and shows rotationally supported kinematics
with $V_{\rm m}/{\sigma}_{0}$ $\sim$ 2.3. (2) The stellar halo is formed during
the interaction, consisting mainly of old stars originating from the outer part
of the initially thin LMC disk. The outer halo shows velocity dispersion of
$\sim$ 40 km s$^{-1}$ at the distance of 7.5 kpc from the LMC center and has
somewhat inhomogeneous distribution of stars. The stellar halo contains
relatively young, metal-rich stars with the mass fraction of 2 %.


title: Dynamics of the Flows Accreting onto a Magnetized Neutron Star

abstract:
  Non-stationary column accretion onto a surface of a magnetized neutron star
is studied with a numerical code based on modified first-order Godunov method
with splitting. Formation and evolution of shocks in the column is modeled for
accretion rates ranging from 10^{15} g/s to 10^{16} g/s and surface magnetic
fields ranging from 5*10^{11} G to 10^{13} G. Non-stationary solutions with
plasma deceleration at collisionless oscillating shocks are found. The kinetic
energy of the accreting flow efficiently transforms into a cyclotron radiation
field. Collisionless stopping of the flow allows a substantial part of
accreting CNO nuclei to avoid spallation and reach the surface. The nuclei
survival fraction depends on the surface magnetic field, being higher at lower
magnetic fields.


title:
Small-scale anisotropy and intermittency in high and low-latitude solar
  wind

abstract:
  We analyze low and high--latitude fast solar wind data from the Ulysses
spacecraft from 1992 to 1994 using a a systematic method to analyse the
anisotropic content of the magnetic field fluctuations. We investigate all
available frequencies, 1-10^{-6} Hz, for both high and low--latitudes datasets
and are able to quantify the relative importance of the anisotropic versus the
isotropic fluctuations. We analyse, up to sixth order, longitudinal, transverse
and mixed magnetic field correlations. Our results show that strongly
intermittent and anisotropic events are present in the solar wind plasma at
high frequencies/small scales, indicating the absence of a complete recovery of
isotropy. Anisotropic scaling properties are compatible for high and
low--latitude data, suggesting a universal behaviour in spite of the different
rate of evolution of the fast solar wind streams in the two environments.


title: Ultra High Energy nu_tau detection at Pierre Auger Observatory

abstract:
  Earth--skimming UHE tau neutrinos have a chance to be detected by the
Fluorescence Detector (FD) of Pierre Auger Observatory if their astrophysical
flux is large enough. A detailed evaluation of the expected number of events is
here performed for a wide class of neutrino flux models.


title:
Structure of visible and dark matter components of spiral galaxies at z
  = 0.9

abstract:
  We construct self-consistent light and mass distribution models for 4 distant
spiral galaxies. The models include a bulge, a disk and an isothermal dark
matter. We find the luminosity profiles to have much steeper cut-off than that
of a simple exponential disk. We apply k-corrections and derive rest-frame
B-band mass-to-light ratios of the visible components and the central densities
of the dark halos; we discover no significant evolution with redshift of these
parameters.


title:
An upper bound on the energy of a gravitationally redshifted
  electron-positron annihilation line from the Crab pulsar

abstract:
  The various changes in the `abstract' are mentioned in point (1) of the
present erratum.


title:
Calibrated Tully-Fisher relations for edge-on galaxies in the BVRI
  system

abstract:
  Calibrated Tully-Fisher relations ''absolute magnitude - HI line width'' for
spiral galaxies oriented edge-on are derived from published data. The slope of
the linear fits, especially in R- and I- bands, is close to the value of -10,
as predicted by the theory. The standard errors of the relations in B, V, R and
I bands are 0.40, 0.36, 0.31 and 0.34 mag, corresponding to relative distance
errors of 18%, 17%, 14% and 16%, respectively. The magnitude of an edge-on
galaxy appears to be a good distance indicator.


title:
Cluster Mergers and Non-Thermal Phenomena: A Statistical
  Magneto-Turbulent Model

abstract:
  With the aim to investigate the statistical properties and the connection
between thermal and non-thermal properties of the ICM in galaxy clusters, we
have developed a statistical magneto-turbulent model which describes, at the
same time, the evolution of the thermal and non-thermal emission from galaxy
clusters. In particular, starting from the cosmological evolution of clusters,
we follow cluster mergers, calculate the spectrum of the magnetosonic waves
generated in the ICM during these mergers, the evolution of relativistic
electrons and the resulting synchrotron and Inverse Compton spectra. We show
that the broad band (radio and hard x-ray) non-thermal spectral properties of
galaxy clusters can be well accounted for by our model for viable values of the
parameters.


title:
Occurence and Luminosity Functions of Giant Radio Halos from
  Magneto-Turbulent Model

abstract:
  We calculate the probability to form giant radio halos (~ 1 Mpc size) as a
function of the mass of the host clusters by using a Statistical
Magneto-Turbulent Model (Cassano & Brunetti, these proceedings). We show that
the expectations of this model are in good agreement with the observations for
viable values of the parameters. In particular, the abrupt increase of the
probability to find radio halos in the more massive galaxy clusters (M >
2x10^{15} solar masses) can be well reproduced. We calculate the evolution with
redshift of such a probability and find that giant radio halos can be powered
by particle acceleration due to MHD turbulence up to z~0.5 in a LCDM cosmology.
Finally, we calculate the expected Luminosity Functions of radio halos (RHLFs).
At variance with previous studies, the shape of our RHLFs is characterized by
the presence of a cut-off at low synchrotron powers which reflects the
inefficiency of particle acceleration in the case of less massive galaxy
clusters.


title: Formation of massive skyrmion stars

abstract:
  As it is well known for stiff equations of state an existence of neutron
stars with masses $\ga 2 M_{\sun}$ is possible. Especially interesting
possibility is opened if the equation of state based on the Skyrme theory is
realized in nature. This equation of state was proposed recently by Ouyed and
Butler. We discuss different channels of formation of massive rapidly rotating
neutron stars. We use a population synthesis code to estimate numbers of
massive neutron stars on different evolutionary stages. A neutron star
increases its mass by accretion from a secondary companion.
  Significant growth of a neutron star mass due to accretion is possible only
for certain values of initial parameters of the binary. In this paper we show
that significant part of massive neutron stars with $M\ga 2 M_{\sun}$ can be
observed as millisecond radio pulsars, as X-ray sources in pair with white
dwarfs, and as accreting neutron stars with very low magnetic fields.


title:
Transforming observational data and theoretical isochrones into the
  ACS/WFC Vega-mag system

abstract:
  We propose a zero-point photometric calibration of the data from the ACS/WFC
on board the Hubble Space Telescope, based on a spectrum of Vega and the most
up to date in-flight transmission curves of the camera. This calibration is
accurate at the level of a few hundredths of a magnitude. The main purpose of
this effort is to transform the entire set of evolutionary models by
Pietrinferni et al. (2004) into a simple observational photometric system for
ACS/WFC data, and make them available to the astronomical community. We provide
the zero points for the most used ACS/WFC bands, and give basic recipes for
calibrating both the observed data and the models.
  We also present the Colour Magnitude Diagram (CMD) from ACS data of 5
Galactic globular clusters, spanning the metallicity range -2.2<[Fe/H]<-0.04,
and provide fiducial points representing their sequences from several
magnitudes below the turnoff to the red giant branch tip. The observed
sequences are compared with the models in the newly defined photometric system.


title: Beta, Local SNIa data and the Great Attractor

abstract:
  We compare the measured peculiar velocities of 98 local (<150/h Mpc) type Ia
supernovae (SNIa) with predictions derived from the PSCz. There is excellent
agreement between the two datasets with a best fit beta_I (=Omega_m^0.6/b_I) of
0.55+-0.06. Subsets of the SNIa dataset are further analysed and the above
result is found to be robust with respect to culls by distance, host-galaxy
extinction and to the reference frame in which the analysis is carried out.
  We briefly review the peculiar motions in the direction of the Great
Attractor. Most clusters in this part of the sky out to a distance of 14,000
km/s, i.e. those closer than the Shapley Concentration, have sizable positive
peculiar velocities, i.e. (~ +400 km/s). There are nine local SNIa in the GA
direction that are in the foreground of Shapley. All these SNIa have positive
peculiar velocities. Hence both the cluster and local SNIa data strongly
support the idea of a sizable flow into Shapley.


title:
Resonantly-forced Eccentric Ringlets: Relationships between Surface
  Density, Resonance location, Eccentricity and Eccentricity-gradient

abstract:
  We use a simple model of the dynamics of a narrow-eccentric ring, to put some
constraints on some of the observable properties of the real systems.In this
work we concentrate on the case of the `Titan ringlet of Saturn'.Our approach
is fluid-like, since our description is based on normal modes of oscillation
rather than in individual particle orbits. Thus, the rigid precession of the
ring is described as a global $m=1$ mode, which originates from a standing wave
superposed on an axisymmetric background. An integral balance condition for the
maintenance of the $m=1$ standing-wave can be set up, in which the differential
precession induced by the oblateness of the central planet must cancel the
contributions of self-gravity, the resonant satellite forcing and collisional
effects. We expect that in nearly-circular narrow rings dominated by
self-gravity, the eccentricity varies linearly across the ring. Thus, we take a
first order expansion and we derive two integral relationships from the
rigid-precession condition. These relate the surface density of the ring with
the eccentricity at the center, the eccentricity gradient and the location of
the secular resonance. These relationships are applied to the Titan ringlet of
Saturn, which has a secular resonance with the satellite Titan in which the
ring precession period is close to Titan's orbital period. In this case, we
estimate the mean surface density and the location of the secular resonance.


title: WWW Database of Models of Accretion Disks Irradiated by The Central Star

abstract:
  We announce the release of a catalog of physical models of irradiated
accretion disks around young stars based on the modelling techniques by
D'Alessio et al. The WWW catalog includes ~ 3000 disk models for different
central stars, disk sizes, inclinations, dust contents and mass accretion
rates. For any of them, radial profiles of disk physical parameters and
synthetic spectral energy distributions can be browsed and downloaded to
compare with observations. It can be accessed at
http://www-cfa.harvard.edu/youngstars/dalessio/ (US),
http://www.astrosmo.unam.mx/~dalessio/ (Mexico), and at
http://www.laeff.esa.es/models/dalessio/ (Spain).


title:
Constraining Galactic Models Through Parallax and Astrometry of
  Microlensing Events

abstract:
  In recent years various models for the Galactic distribution of massive
compact halo objects (MACHOs) have been proposed for the interpretation of
microlensing toward the Large Magellanic Cloud (LMC). A direct way to fit the
best model is by measuring the lens parameters, which can be obtained by
measuring the Einstein crossing time and the parallax effect on the
microlensing light curve and by astrometry of centroids of images. In this
work, the theoretical distribution of these parameters is obtained for the
various power-law Galactic dark halo models and MACHO mass functions (MF). For
self-lensing as one of the models for the interpretation of LMC events, the
maximum shift of image centroids and the parallax parameter are one order of
magnitude smaller than for models with dark halos. This can be used as a test
for the self-lensing, although the shifting of image centroids 0.02 {\it mas},
for the LMC events is unlikely to be observed by the astrometric missions such
as FAME, GAIA and SIM.


title: Classical nova explosions

abstract:
  A review of the present status of nova modeling is made, with a special
emphasis on some specific aspects. What are the main nucleosynthetic products
of the explosion and how do they depend on the white dwarf properties (e.g.
mass, chemical composition: CO or ONe)? What's the imprint of nova
nucleosynthesis on meteoritic presolar grains? How can gamma rays, if observed
with present or future instruments onboard satellites, constrain nova models
through their nucleosynthesis? What have we learned about the turnoff of
classical novae from observation with past and present X-ray observatories? And
last but not least, what are the most critical issues concerning nova modeling
(e.g. ejected masses, mixing mechanism between core and envelope)?


title: Extended quintessence with an exponential coupling

abstract:
  We study a class of extended quintessence cosmologies where the scalar field
playing the role of the dark energy is exponentially coupled to the Ricci
scalar. We find that the dynamics induced by the effective gravitational
potential in the Klein-Gordon equation dominates the motion of the field in the
early universe. The resulting "R-boost" trajectory is characterized by a
kinetic dark energy density, given by [3\rhomnr0(1+z)]^2 [ 32 rhor0
omegaJBD0]^(-1), where omegaJBD0, rhor0 and rhomnr0 are calculated at present,
and represent the Jordan Brans Dicke parameter, the density of relativistic
matter and of those species which are non-relativistic at redshift z,
respectively. We show that such a trajectory represents an attractor,
equivalent to a tracking solution with equation of state w=-1/3, providing a
large basin of attraction for the initial dark energy density regardless of the
properties of the potential energy yielding acceleration today. We derive the
up to date constraints from Big Bang Nucleosynthesis (BBN) on the present
scenario, and we show that they are largely satisfied for interesting
trajectories of the dark energy scalar field in the early universe. We compute
the cosmological perturbation spectra in these cosmologies. For a fixed value
of omegaJBD0, the projection and Integrated Sachs-Wolfe effects on the cosmic
microwave background anisotropy are considerably larger in the exponential case
with respect to a quadratic non-minimal coupling, reflecting the fact that the
effective gravitational constant depends exponentially on the dynamics of the
field.


title:
X-ray Bright Optically Inactive Galaxies (XBONG) in XMM-Newton/SDSS
  fields: more diluted than absorbed?

abstract:
  We explore the properties of X-ray Bright Optically Inactive Galaxies (XBONG)
detected in the 0.5-8 keV spectral band in 20 public XMM fields overlapping
with the SDSS. We constrain our sample to optically extended systems with log
(f_X/f_o > -2) that have spectroscopic identifications available from the SDSS
(r<19.2 mag). The resulting sample contains 12 objects with L_X (0.5-8keV)= 5 x
10^41 - 2x10^44 erg s-1 in the redshift range 0.06 < z < 0.45. The X-ray
emission in four cases is extended suggesting the presence of hot gas
associated with a cluster or group of galaxies. The X-ray spectral fits show
that two additional sources are best fit with a thermal component emission (kT
\~ 1 keV). Three sources aremost likely associated with AGN: their X-ray
spectrum is described by a steep photon index ~ 1.9 typical of unobscured AGN
while, they are very luminous in X-rays (L_X (0.5-8 keV) ~ 10^43 - 10^44 erg
s-1.) Finally, three more sources could be associated with either normal
galaxies or unobscured Low Luminosity AGN (L_X < 10^42 erg s-1). We find no
evidence for significant X-ray absorbing columns in any of our XBONGs. The
above suggest that XBONGs, selected in the total 0.5-8 keV band, comprise a
mixed bag of objects primarily including normal elliptical galaxies and type-1
AGN whose optical nuclear spectrum is probably diluted by the strong stellar
continuum. Nevertheless, as our sample is not statistically complete we cannot
exclude the possibility that a fraction of optically fainter XBONG may be
associated with heavily obscured AGN.


title: Imaging Protoplanetary Disks with a Square Kilometer Array

abstract:
  The recent detections of extrasolar giant planets has revealed a surprising
diversity of planetary system architectures, with many very unlike our Solar
System. Understanding the origin of this diversity requires multi-wavelength
studies of the structure and evolution of the protoplanetary disks that
surround young stars. Radio astronomy and the Square Kilometer Array will play
a unique role in these studies by imaging thermal dust emission in a
representative sample of protoplanetary disks at unprecedented sub-AU scales in
the innermost regions, including the ``habitable zone'' that lies within a few
AU of the central stars. Radio observations will probe the evolution of dust
grains up to centimeter-sized ``pebbles'', the critical first step in
assembling giant planet cores and terrestrial planets, through the wavelength
dependence of dust emissivity, which provides a diagnostic of particle size.
High resolution images of dust emission will show directly mass concentrations
and features in disk surface density related to planet building, in particular
the radial gaps opened by tidal interactions between planets and disks, and
spiral waves driven by embedded protoplanets. Moreover, because orbital
timescales are short in the inner disk, synoptic studies over months and years
will show proper motions and allow for the tracking of secular changes in disk
structure. SKA imaging of protoplanetary disks will reach into the realm of
rocky planets for the first time, and they will help clarify the effects of the
formation of giant planets on their terrestrial counterparts.


title:
Resolved Mid-Infrared Emission Around AB Aur and V892 Tau with Adaptive
  Optics Nulling Interferometric Observations

abstract:
  We present the results of adaptive optics nulling interferometric
observations of two Herbig Ae stars, AB Aur and V892 Tau. Our observations at
10.3 microns show resolved circumstellar emission from both sources. Further
analysis of the AB Aur emission suggests that there is an inclined disk
surrounding the star. The diameter of the disk is derived to be 24 to 30 AU
with an inclination of 45 to 65 degrees from face-on, and a major-axis PA of 30
+/- 15 degrees (E of N). Differences in the physical characteristics between
the mid-IR emission and emission at other wavelengths (near-IR and millimeter),
found in previous studies, suggest a complex structure for AB Aur's
circumstellar environment, which may not be explained by a disk alone. The
similarity in the observed size of AB Aur's resolved emission and that of
another Herbig Ae star, HD 100546, is likely coincidental, as their respective
evolutionary states and spectral energy distributions suggest significantly
different circumstellar environments.


title: Depth Development of Extensive Air Showers from Muon Time Distributions

abstract:
  We develop a potential algorithm to relate the depth development of ultra
high energy extensive air showers and the time delay for individual muons. The
time distributions sampled at different positions at ground level by a large
air shower array are converted into distributions of production distances using
an approximate relation between production distance, transverse distance and
time delay. The method is naturally restricted to inclined showers where muons
dominate the signal at ground level but could be extended to vertical showers
provided that the detectors used can separate the muon signal from electrons
and photons. We explore the accuracy and practical uncertainties involved in
the proposed method. For practical purposes only the muons that fall outside
the central region of the shower can be used, and we establish cuts in
transverse distance. The method is tested using simulated showers by comparing
the production distance distributions obtained using the method with the actual
distances in the simulated showers. It could be applied in the search of
neutrinos to increase the acceptance to highly penetrating particles, as well
as for unraveling the relative compositions of protons and heavy nuclei. We
also illustrate that the obtained depth distributions have minimum width when
both the arrival direction and the core position are well reconstructed.


title: Fe L-Shell Density Diagnostics in Theory and Practice

abstract:
  We provide a discussion of the density and photoexcitation sensitivity of the
X-ray spectra of Fe L-shell ions (Fe XVII-Fe XXIV) calculated with the
Livermore X-ray Spectral Synthesizer, a suite of IDL codes that calculates
spectral models of highly charged ions based primarily on HULLAC atomic data.
These models are applicable to collisionally ionized laboratory or cosmic
plasmas with electron temperatures T_e ~ 2-45 MK (0.2-4 keV) and electron
densities n_e > 1E11 cm^{-3}. Potentially useful density diagnostics are
identified for Fe XVII and Fe XIX-Fe XXIII, with the most straightforward being
the Fe XVII I(17.10 A)/I(17.05 A) line ratio and the Fe XXII I(11.92 A)/I(11.77
A) line ratio. Applying these models to the Chandra X-ray Observatory High
Energy Transmission Grating spectrum of the intermediate polar EX Hya, we find
that the strength of all the Fe L-shell lines are consistent with electron
densities n_e > 1E14 cm^{-3}. Specifically, from the observed Fe XVII I(17.10
A)/I(17.05 A) line ratio, we infer an electron density n_e > 2E14 cm^{-3} at
the 3 sigma level, while from the observed Fe XXII I(11.92 A)/I(11.77 A) line
ratio, we infer n_e = 1.0^{+2.0}_{-0.5}E14 cm^{-3} at the 1 sigma level and n_e
> 2E13 cm^{-3} at the 3 sigma level.


title: Observational tests of the evolution of spheroidal galaxies

abstract:
  Granato et al (2004) have elaborated a physically grounded model exploiting
the mutual feedback between star-forming spheroidal galaxies and the active
nuclei growing in their cores to overcome, in the framework of the hierarchical
clustering scenario for galaxy formation, one of the main challenges facing
such scenario, the fact that massive spheroidal galaxies appear to have formed
much earlier and faster than predicted by previous semi-analytical models.
After having assessed the values of the two parameters that control the effect
of the complex radiative transfer processes on the time-dependent SEDs we have
compared the model predictions with a variety of IR to mm data. Our results
support a rather strict continuity between objects where stars formed and
evolved massive early-type galaxies, indicating that large spheroidal galaxies
formed most of their stars when they were already assembled as single objects.
The model is successful in reproducing the observed z distribution of K\le20
galaxies at z>1, in contrast with both the classical monolithic and the
semi-analytic models, the ratio of star-forming to passively evolving spheroids
and the counts and z distributions of EROs. The model also favourably compares
with the ISOCAM 6.7 mu counts, with the corresponding z distribution, and with
IRAC counts, which probe primarily the passive evolution phase, and with the
submm SCUBA and MAMBO data, probing the active star-formation phase. The
observed fraction of 24mu selected sources with no detectable emission in
either the 8mu or R band nicely corresponds to the predicted surface density of
star-forming spheroids with 8mu fluxes below the detection limit. Predictions
for the z distributions of 24mu sources detected by MIPS surveys are pointed
out. [Abridged]


title: Choice of Observing Schedules for Astrometric Planet Searches

abstract:
  The Space Interferometry Mission (SIM) will make precise astrometric
measurements that can be used to detect planets around nearby stars. Since
observational time will be extremely valuable, it is important to consider how
the choice of the observing schedule influences the efficiency of SIM planet
searches. We have conducted Monte Carlo simulations of astrometric observations
to understand the effects of different scheduling algorithms. We find that the
efficiency of planet searches is relatively insensitive to the observing
schedule for most reasonable observing schedules.


title:
Dynamo models and differential rotation in late-type rapidly rotating
  stars

abstract:
  Increasing evidence is becoming available about not only the surface
differential rotation of rapidly rotating cool stars but, in a small number of
cases, also about temporal variations, which possibly are analogous to the
solar torsional oscillations. Given the present difficulties in resolving the
precise nature of such variations, due to both the short length and poor
resolution of the available data, theoretical input is vital to help assess the
modes of behaviour that might be expected, and will facilitate interpretation
of the observations. Here we take a first step in this direction by studying
the variations in the convection zones of such stars, using a two dimensional
axisymmetric mean field dynamo model operating in a spherical shell in which
the only nonlinearity is the action of the azimuthal component of the Lorentz
force of the dynamo generated magnetic field on the stellar angular velocity.
We consider three families of models with different depths of dynamo-active
regions. For moderately supercritical dynamo numbers we find torsional
oscillations that penetrate all the way down to the bottom of the convection
zones, similar to the case of the Sun. For larger dynamo numbers we find
fragmentation in some cases and sometimes there are other dynamical modes of
behaviour, including quasi-periodicity and chaos. We find that the largest
deviations in the angular velocity distribution caused by the Lorentz force are
of the order of few percent, implying that the original assumed `background'
rotation field is not strongly distorted.


title:
Properties of Ly-alpha and Gamma Ray Burst selected starbursts at high
  redshifts

abstract:
  Selection of starbursts through either deep narrow band imaging of redshifted
Ly-alpha emitters, or localisation of host galaxies of gamma-ray bursts both
give access to starburst galaxies that are significantly fainter than what is
currently available from selection techniques based on the continuum (such as
Lyman-break selection). We here present results from a survey for Ly-alpha
emitters at z=3, conducted at the European Southern Observatory's Very Large
Telescope. Furthermore, we briefly describe the properties of host galaxies of
gamma-ray bursts at z>2. The majority of both Ly-alpha and gamma-ray burst
selected starbursts are fainter than the flux limit of the Lyman-break galaxy
sample, suggesting that a significant fraction of the integrated star formation
at z~3 is located in galaxies at the faint end of the luminosity function.


title:
Interstellar dust: what is it, how does it evolve, and what are its
  observational consequences?

abstract:
  This paper reviews our current understanding of interstellar dust models,
what constitutes a viable dust model, what observational constraints are
essential for deriving such model, and the current viable dust models.
Interstellar dust exhibits spatial and temporal variations, and the paper
reviews the ingredients in constructing models for the evolution of dust,
stressing the current uncertainties in the yield of dust from supernovae and
AGB stars. Finally, the paper briefly describes the effect of dust evolution on
the spectral energy distribution of galaxies, and, using a very simple
criterion, present a rough estimate of the redshift when galaxies first become
opaque.


title: Fundamental Properties of O-Type Stars

abstract:
  We present a comprehensive analysis of high-resolution, far-UV HST/STIS,
FUSE, and optical spectra of 17 O stars in the SMC. Our analysis is based on
NLTE metal line-blanketed model atmospheres calculated with our NLTE code
TLUSTY. We systematically explore the sensitivity of various UV and optical
lines to different stellar parameters. We have obtained consistent fits of the
UV and the optical spectrum to derive the effective temperature, surface
gravity, surface composition, and microturbulent velocity of each star. Stellar
radii, masses, luminosities and ages then follow. Similarly to more limited
recent studies, we derive cooler temperatures than the standard Teff
calibration of O stars. We propose a new calibration between the spectral type
and effective temperature based on our results from UV metal lines as well as
optical hydrogen and helium lines. For stars of the same spectral subtype, we
find a general good agreement between Teff determinations obtained with TLUSTY,
CMFGEN, and FASTWIND models. We derive ionizing luminosities that are smaller
by a factor of 3 compared to luminosities inferred from previous standard
calibrations. The chemical composition analysis reveals that the surface of
about 3/4 of the program stars is moderately to strongly enriched in nitrogen,
while showing the original helium, carbon, and oxygen abundances. Our results
support the new stellar evolution models that predict that the surface of fast
rotating stars becomes N-rich during the main sequence phase because of
rotationally-induced mixing. Most stars exhibit the ``mass discrepancy''
problem. This discrepancy too is a result of fast rotation which lowers the
measured effective gravity. Our study thus emphasizes the importance of
rotation in our understanding of the properties of massive stars. (abridged)


title:
Low mass loss rates in O-type stars: Spectral signatures of dense clumps
  in the wind of two Galactic O4 stars

abstract:
  We have analyzed the far-UV spectrum of two Galactic O4 stars, the O4If+
supergiant HD190429A and the O4V((f)) dwarf HD96715, using archival FUSE and
IUE data. We have conducted a quantitative analysis based on the two NLTE model
atmosphere and wind codes, TLUSTY and CMFGEN. We have derived the stellar and
wind parameters and the surface composition of the two stars. The surface of
HD190429A has a composition typical of an evolved O supergiant (N-rich, C and
O-poor), while HD96715 exhibits surface N enhancement similar to the enrichment
found in SMC O dwarfs and attributed to rotationally-induced mixing. We find
that homogeneous wind models could not match the observed profile of O V1371
and require very low phosphorus abundance to fit the P V1118-1128 resonance
lines. However, we are able to match the O V and P V lines using clumped wind
models. We find that N IV1718 is also sensitive to wind clumping. For both
stars, we have calculated clumped wind models that match well all these lines
from different species and that remain consistent with Halpha data. These fits
therefore provide a coherent and thus much stronger evidence of wind clumping
in O stars than earlier claims. We find that the wind of these two stars is
highly clumped, as expressed by very small volume filling factors, namely
f=0.04 for HD190429A and f=0.02 for HD96715. In agreement with our analysis of
SMC stars, clumping starts deep in the wind, just above the sonic point. The
most crucial consequence of our analysis is that the mass loss rates of O stars
need to be revised downward significantly, by a factor of 3 and more.
Accounting for wind clumping is essential when determining the wind properties
of O stars. Our study therefore calls for a fundamental revision in our
understanding of mass loss and of O-type star winds. (abridged)


title:
Search for extraterrestrial point sources of high energy neutrinos with
  AMANDA-II using data collected in 2000-2002

abstract:
  The results of a search for point sources of high energy neutrinos in the
northern hemisphere using data collected by AMANDA-II in the years 2000, 2001
and 2002 are presented. In particular, a comparison with the single-year result
previously published shows that the sensitivity was improved by a factor of
2.2. The muon neutrino flux upper limits on selected candidate sources,
corresponding to an E^{-2} neutrino energy spectrum, are included. Sky grids
were used to search for possible excesses above the background of cosmic ray
induced atmospheric neutrinos. This search reveals no statistically significant
excess for the three years considered.


title:
High resolution SPH simulations of disk formation in CDM halos;
  resolution tests

abstract:
  We perform N-Body/SPH simulations of disk galaxy formation inside equilibrium
spherical and triaxial cuspy dark matter halos. We systematically study the
disk properties and morphology as we increase the numbers of dark matter and
gas particles from 10^4 to 10^6 and change the force resolution. The force
resolution influences the morphological evolution of the disk quite
dramatically. Unless the baryon fraction is significantly lower than the
universal value, with high force resolution a gaseous bar always forms within a
billion years after allowing cooling to begin. The bar interacts with the disk,
transferring angular momentum and increasing its scale length. In none of the
simulations does the final mass distribution of the baryons obey a single
exponential profile. Indeed within a few hundred parsecs to a kiloparsec from
the center the density rises much more steeply than in the rest of the disk,
and this is true irrespective of the presence of the bar.


title: Live Fe-60 in the Early Solar System

abstract:
  The latest finding by Hester et al. supports the view of ". . . iron cores of
the inner planets, iron meteorites, and the core of the sun as likely
condensation products from the supernova core." [Science 195, 209 (14 January
1977)]


title: A Possible Detection of M31* with Chandra

abstract:
  Two independent sets of Chandra and HST images of the nuclear region of M31
allow registration of X-ray and optical images to 0.1''. This registration
shows that none of the bright (10^{37} erg/s) X-ray sources near the nucleus is
coincident with the central super-massive black hole, M31*. A 50ks Chandra HRC
image shows 2.5 sigma evidence for a faint (3 x 10^{35} erg/s), apparently
resolved source which is consistent with the position of the M31*. The Bondi
radius of M31* is 0.9'', making it one of the few super-massive black holes
with a resolvable accretion flow. This large radius and the previous detections
of diffuse, X-ray emitting gas in the nuclear region make M31* one of the most
secure cases for a radiatively inefficient accretion flow and place some of the
most severe constraints on the radiative processes in such a flow.


title: Highly-Ionized Oxygen Absorbers in the Intergalactic Medium

abstract:
  Recent ultraviolet and X-ray observations of intergalactic OVI and OVII
absorption systems along lines of sight to bright quasars have opened a new
window onto the ``warm-hot intergalactic medium'' (WHIM). These systems appear
to provide a significant reservoir for baryons in the local universe, and
comparison to cosmological simulations suggests that their abundance roughly
matches theoretical predictions. Here we use analytic arguments to elucidate
the physical properties of the absorbers and their role in structure formation.
We first show that if the absorbers result from structure-formation shocks, the
observed column densities naturally follow from postshock-cooling models, if we
include fast-cooling shocks as well as those that cannot cool within a Hubble
time. In this case, the known OVI absorbers should show stronger OVII
absorption than expected from collisional-ionization equilibrium (and much more
than expected for photoionized systems). We then argue that higher-temperature
shocks will be spatially associated with more massive virialized objects even
well outside the virial radius. Thus the different oxygen ions will trace
different structures; OVII absorbers are the most common because that ion
dominates over a wide temperature range (corresponding to a large range in halo
mass). If each dark-matter halo is surrounded by a network of shocks with total
cross section a few times the size of the virialized systems, then we can
reproduce the observed number densities of absorbers with plausible parameters.
A simple comparison with simulations shows that these assumptions are
reasonable, although the actual distribution of shocked gas is too complex for
analytic models to describe fully. Our models suggest that these absorbers
cannot be explained as a single-temperature phase.


title:
A Green Bank Telescope Search for Water Masers in Nearby Active Galactic
  Nuclei

abstract:
  Using the Green Bank Telescope, we have conducted a survey for 1.3 cm water
maser emission toward the nuclei of nearby active galaxies, the most sensitive
large survey for H2O masers to date. Among 145 galaxies observed, maser
emission was newly detected in eleven sources and confirmed in one other. Our
survey targeted nearby (v < 12,000 km/s, mainly type 2 AGNs north of
declination -20 degrees, and includes a few additional sources as well. We find
that more than a third of Seyfert 2 galaxies have strong maser emission, though
the detection rate declines beyond v about 5000 km/s due to sensitivity limits.
Two of the masers discovered during this survey are found in unexpected hosts:
NGC 4151 (Seyfert 1.5) and NGC 2782 (starburst). We discuss the possible
relations between the large X-ray column to NGC 4151 and a possible hidden AGN
in NGC 2782 to the detected masers. Four of the masers discovered here, NGC
591, NGC 4388, NGC 5728 and NGC 6323, have high-velocity lines symmetrically
spaced about the systemic velocity, a likely signature of molecular gas in a
nuclear accretion disk. The maser source in NGC 6323, in particular, reveals
the classic spectrum of a "disk maser" represented by three distinct groups of
Doppler components. Future single-dish and VLBI observations of these four
galaxies could provide a measurement of the distance to each galaxy, and of the
Hubble constant, independent of standard candle calibrations.


title:
Simulating Astro-E2 Observations of Galaxy Clusters: the Case of
  Turbulent Cores Affected by Tsunamis

abstract:
  This is the first attempt to construct detailed X-ray spectra of clusters of
galaxies from the results of high-resolution hydrodynamic simulations and
simulate X-ray observations in order to study velocity fields of the
intracluster medium (ICM). The hydrodynamic simulations are based on the
recently proposed tsunami model, in which cluster cores are affected by bulk
motions of the ICM and turbulence is produced. We note that most other
solutions of the cooling flow problem also involve the generation of turbulence
in cluster cores. From the mock X-ray observations with Astro-E2 XRS, we find
that turbulent motion of the ICM in cluster cores could be detected with the
satellite. The Doppler shifts of the metal lines could be used to discriminate
among turbulence models. The gas velocities measured through the mock
observations are consistent with the line-emission weighted values inferred
directly from hydrodynamic simulations.


title: From COBE to WMAP: A Decade of Data Under Scrutiny

abstract:
  This talk, presented at the 5th Rencontres du Vietnam 2004, gives a review of
the cosmological implications of the cosmic microwave background (CMB) data.
The observational progress that has been made over the past decade is discussed
and recent constraints on cosmological parameters are given. The concordance
model is presented and the implications of the most recent data for
cosmological inflation, reionisation and dark energy are described. Finally,
the expectations for the next decade of CMB cosmology are summarised.


title: Magnetospheric eclipses in the double pulsar system J0737-3039

abstract:
  We argue that eclipses of radio emission from the millisecond pulsar A in the
double pulsar system J0737-3039 are due to synchrotron absorption by plasma in
the closed field line region of the magnetosphere of its normal pulsar
companion B. A's radio beam only illuminates B's magnetosphere for about 10
minutes surrounding the time of eclipse. During this time it heats particles at
r\gtrsim 10^9 cm to relativistic energies and enables extra plasma to be
trapped by magnetic mirroring. An enhancement of the plasma density by a factor
\sim 10^2 is required to match the duration and optical depth of the observed
eclipses. The extra plasma might be supplied by a source near B through B\gamma
pair creation by energetic photons produced in B's outer gap. Excitation of
pairs' gyrational motions by cyclotron absorption of A's radio beam can result
in their becoming trapped between conjugate mirror points in B's magnetosphere.
Because the trapping efficiency decreases with increasing optical depth, the
plasma density enhancement saturates even under steady state illumination. The
result is an eclipse with finite, frequency dependent, optical depth. After
illumination by A's radio beam ceases, the trapped particles cool and are lost.
The entire cycle repeats every orbital period. We speculate that the
asymmetries between eclipse ingress and egress result in part from the
magnetosphere's evolution toward a steady state when illuminated by A's radio
beam. We predict that A's linear polarization will vary with both eclipse phase
and B's rotational phase.


title:
How Dry is the Brown Dwarf Desert?: Quantifying the Relative Number of
  Planets, Brown Dwarfs and Stellar Companions around Nearby Sun-like Stars

abstract:
  Sun-like stars have stellar, brown dwarf and planetary companions. To help
constrain their formation and migration scenarios, we analyse the close
companions (orbital period < 5 years) of nearby Sun-like stars. By using the
same sample to extract the relative numbers of stellar, brown dwarf and
planetary companions, we verify the existence of a very dry brown dwarf desert
and describe it quantitatively. With decreasing mass, the companion mass
function drops by almost two orders of magnitude from 1 M_Sun stellar
companions to the brown dwarf desert and then rises by more than an order of
magnitude from brown dwarfs to Jupiter-mass planets. The slopes of the
planetary and stellar companion mass functions are of opposite sign and are
incompatible at the 3 sigma level, thus yielding a brown dwarf desert. The
minimum number of companions per unit interval in log mass (the driest part of
the desert) is at M = 31^{+25}_{-18} M_Jup. Approximately 16% of Sun-like stars
have close (P < 5 years) companions more massive than Jupiter: 11% +- 3% are
stellar, <1% are brown dwarf and 5% +- 2% are giant planets. The steep decline
in the number of companions in the brown dwarf regime, compared to the initial
mass function of individual stars and free-floating brown dwarfs, suggests
either a different spectrum of gravitational fragmentation in the formation
environment or post-formation migratory processes disinclined to leave brown
dwarfs in close orbits.


title: Thermal Physics, Cloud Geometry, and the Stellar IMF

abstract:
  The thermal properties of star-forming clouds have an important influence on
how they fragment into stars, and it is suggested in this paper that the
low-mass stellar IMF, which appears to be almost universal, is determined
largely by the thermal physics of these clouds. In particular, it is suggested
that the characteristic stellar mass, a little below one solar mass, is
determined by the transition from an initial cooling phase of collapse to a
later phase of slowly rising temperature that occurs when the gas becomes
thermally coupled to the dust. Numerical simulations support the hypothesis
that the Jeans mass at this transition point plays an important role in
determining the peak mass of the IMF. A filamentary geometry may also play a
key role in the fragmentation process because the isothermal case is a critical
one for the collapse of a cylinder: the collapse and fragmentation of a
cylinder can continue freely as long as the temperature continues to decrease,
but not if it begins to increase. The limited available results on the
dependence of the thermal properties of clouds on metallicity do not suggest a
strong dependence of the IMF on metallicity, but the far-infrared background
radiation in starburst regions and in the early universe may significantly
shift the peak mass to higher masses in these situations.


title: Specific Star Formation Rates to Redshift 1.5

abstract:
  We present a study to determine how star formation contributes to galaxy
growth since z=1.5 over five decades in galaxy stellar mass. We investigate the
specific star formation rate (SSFR; star formation rate [SFR] per unit galaxy
stellar mass) as a function of galaxy stellar mass and redshift. A sample of
175 K-band selected galaxies from the MUnich Near-Infrared Cluster Survey
spectroscopic dataset provide intermediate to high mass galaxies (mostly M* >
10^10 Msun) to z=1. The FORS Deep Field provides 168 low mass galaxies (mostly
M* < 10^10 Msun) to z=1.5. We use a Sloan Digital Sky Survey galaxy sample to
test the compatibility of our results with data drawn from a larger volume. We
find that at all redshifts, the SSFR decreases with increasing galaxy stellar
mass suggesting that star formation contributes more to the growth of low mass
galaxies than to the growth of high mass galaxies, and that high mass galaxies
formed the bulk of their stellar content before z=1. At each epoch we find a
ridge in SSFR versus stellar mass that is parallel to lines of constant SFR and
evolves independently of galaxy stellar mass to a particular turnover mass.
Galaxies above this turnover mass show a sharp decrease in the SFR compared to
the average at each epoch and the turnover mass increases with redshift. The
SFR along the SSFR ridge decreases by roughly a factor of 10, from 10 Msun/yr
at z=1.5 to 1 Msun/yr at z=0. High mass galaxies could sustain the observed
rates of star formation over the 10 Gyr observed, but low mass galaxies likely
undergo episodic starbursts.


title: MHD Simulations of a Moving Subclump with Heat Conduction

abstract:
  High resolution observations of cluster of galaxies by Chandra have revealed
the existence of an X-ray emitting comet-like galaxy C153 in the core of
cluster of galaxies A2125. The galaxy C153 moving fast in the cluster core has
a distinct X-ray tail on one side, obviously due to ram pressure stripping,
since the galaxy C153 crossed the central region of A2125. The X-ray emitting
plasma in the tail is substantially cooler than the ambient plasma. We present
results of two-dimensional magnetohydrodynamic simulations of the time
evolution of a subclump like C153 moving in magnetized intergalactic matter.
Anisotropic heat conduction is included. We found that the magnetic fields are
essential for the existence of the cool X-ray tail, because in non-magnetized
plasma the cooler subclump tail is heated up by isotropic heat conduction from
the hot ambient plasma and does not form such a comet-like tail.


title:
The XMM-Newton spectrum of the high-z optically-obscured QSO RX
  J1343.4+0001: a classic radio quiet QSO

abstract:
  We present a 30 ks XMM-Newton observation of the z = 2.35 Type II radio quiet
quasar RX J1343.4+0001. These data provide the first good quality X-ray
spectrum for this object. We measured a continuum slope Gamma = 1.85+/-0.10
with only an upper limit on the column density of the absorbing material of
Nh(z) <~ 10^22 cm^-2 as well as an Fe Kalpha emission line at the 3 sigma
confidence level. We do not find therefore a highly absorbed object nor a truly
flat spectrum as suggested on the basis of previous less sensitive ROSAT and
ASCA measurements. The Nh(z) upper limit is fully consistent with the optical
extinction 3 <A_V <10 inferred from IR observations. The Fe Kalpha line is
consistent with fluorescence from neutral iron and, noteworthy, is one of the
most distant observed so far. The X-ray spectral properties of RX J1343.4+0001
agree well with the steep continuum slope (Gamma ~ 1.9) being independent of
increasing redshift and luminosity as inferred by X-ray studies of large
samples of RQ QSOs.


title:
Photon-Dominated Chemistry in the Nucleus of M82: Widespread HOC+
  emission in the inner 650 pc disk

abstract:
  The nucleus of M82 has been mapped in several 3mm and 1mm lines of CN, HCN,
C2H, c-C3H2, CH3C2H, HC3N and HOC+ using the IRAM 30m telescope. These species
have been purposely selected as good tracers of photon-dominated chemistry. We
have measured [CN]/[HCN] ~ 5 in the inner 650 pc galaxy disk. Furthermore, we
have detected the HOC+ 1--0 line with an intensity similar to that of the
H13CO+ 1--0 line. This implies a [HCO+]/[HOC+] ratio of ~40. These results
corroborate the existence of a giant photo-dissociation region (PDR) in the
nucleus of M82. In fact, the low [HCO+]/[HOC+] ratio can only be explained if
the nucleus of M82 is formed by small (r<0.02-0.2 pc) and dense (n ~ a few
10^4--10^5 cm^{-3}) clouds immersed in an intense UV field (G_0 ~ 10^4 in units
of the Habing field). The detection of the hydrocarbons c-C3H2 and CH3C2H in
the nucleus of M82 suggests that a complex carbon chemistry is developing in
this giant PDR.


title:
Alfven Wave-Driven Proto-Neutron Star Winds And R-Process
  Nucleosynthesis

abstract:
  We propose magnetic proto-neutron star (PNS) winds driven by \Alfven waves as
well as the neutrino heating as an appropriate site for the r-process
nucleosynthesis. \Alfven waves excited by surface motions of a PNS propagate
outwardly, and they heat and accelerate the wind by dissipation. Compared with
the wind purely driven by the neutrino heating, larger entropy per baryon and
shorter dynamical time scale are achieved, which favors the r-process. We study
reasonable cases that a wave amplitude is 10% of \Alfven speed at the surface
to find that a PNS with surface field strength, $\gtrsim 5\times 10^{14}$G,
gives suitable wind properties for the r-process, provided that dissipation
length of the wave is at most $\sim$ 10 times of the PNS radius. We also
compare properties of transcritical and subcritical winds in light of the
r-process. We finally discuss possibilities of detections of $\gamma$-rays from
radioactive nuclei and absorption lines due to Ba in supernova remnants which
possess magnetars.


title:
Shearing and embedding box simulations of the magnetorotational
  instability

abstract:
  Two different computational approaches to the magnetorotational instability
(MRI) are pursued: the shearing box approach which is suited for local
simulations and the embedding box approach whereby a Taylor Couette flow is
embedded in a box so that numerical problems with the coordinate singularity
are avoided. New shearing box simulations are presented and differences between
regular and hyperviscosity are discussed. Preliminary simulations of spherical
nonlinear Taylor Couette flow in an embedding box are presented and the effects
of an axial field on the background flow are studied.


title: The problem of small and large scale fields in the solar dynamo

abstract:
  Three closely related stumbling blocks of solar mean field dynamo theory are
discussed: how dominant are the small scale fields, how is the alpha effect
quenched, and whether magnetic and current helicity fluxes alleviate the
quenching? It is shown that even at the largest currently available resolution
there is no clear evidence of power law scaling of the magnetic and kinetic
energy spectra in turbulence. However, using subgrid scale modeling, some
indications of asymptotic equipartition can be found. The frequently used first
order smoothing approach to calculate the alpha effect and other transport
coefficients is contrasted with the superior minimal tau approximation. The
possibility of catastrophic alpha quenching is discussed as a result of
magnetic helicity conservation. Magnetic and current helicity fluxes are shown
to alleviate catastrophic quenching in the presence of shear. Evidence for
strong large scale dynamo action, even in the absence of helicity in the
forcing, is presented.


title:
VLT adaptive optics imaging of QSO host galaxies and close environment
  at z ~2.5: results from a pilot program

abstract:
  We report ESO-VLT near-infrared adaptive optics imaging of one radio-loud
(PKS 0113-283) and two radio-quiet (Q 0045-3337 and Q 0101-337) QSOs at z > 2.
In the first case, we are able to resolve the QSO and find that it is hosted by
an elliptical of absolute magnitude M(K) = -27.6. For the other two objects, no
extended emission has been unambiguously detected. This result, though
restricted to a single object, extends up to z ~2.5 the finding that cosmic
evolution of radio-loud QSO hosts follows the trend expected for luminous and
massive spheroids undergoing passive evolution. For Q 0045-3337, our high
resolution images show that it is located 1.2 arcsec from a K = 17.5 foreground
disc galaxy, which may act as a gravitational lens, since the QSO most probably
lies within the galaxy Einstein radius.


title: Importance of magnetic helicity in dynamos

abstract:
  Magnetic helicity is nearly conserved and its evolution equation provides a
dynamical feedback on the alpha effect that is distinct from the conventional
algebraic alpha quenching. The seriousness of this dynamical alpha quenching is
particularly evident in the case of closed or periodic boxes. The explicit
connection with catastrophic alpha quenching is reviewed and the alleviating
effects of magnetic and current helicity fluxes are discussed.


title:
B-type Supergiants in the SMC: Chemical compositions and comparison of
  static and unified models

abstract:
  High-resolution UCLES/AAT spectra are presented for nine B-type supergiants
in the SMC, chosen on the basis that they may show varying amounts of
nuclear-synthetically processed material mixed to their surface. These spectra
have been analysed using a new grid of approximately 12 000 non-LTE line
blanketed {\sc tlusty} model atmospheres to estimate atmospheric parameters and
chemical composition. The abundance estimates for O, Mg and Si are in excellent
agreement with those deduced from other studies, whilst the low estimate for C
may reflect the use of the \ion{C}{ii} doublet at 4267\AA. The N estimates are
approximately an order of magnitude greater than those found in unevolved
B-type stars or \ion{H}{ii} regions but are consistent with the other estimates
in AB-type supergiants. These results have been combined with results from a
unified model atmosphere analysis of UVES/VLT spectra of B-type supergiants
(Trundle et al. \cite{Tru04}) to discuss the evolutionary status of these
objects. For two stars that are in common with those discussed by Trundle et
al., we have undertaken a careful comparison in order to try to understand the
relative importance of the different uncertainties present in such analyses,
including observational errors and the use of static or unified models. We find
that even for these relatively luminous supergiants, {\sc tlusty} models yield
atmospheric parameters and chemical compositions similar to those deduced from
the unified code {\sc fastwind}.


title:
Geometrical constraints upon the unipolar model of V407 Vul and
  RXJ0806.3+1527

abstract:
  V407 Vul and RX J0806.3+1527 are X-ray emitting stars with X-ray light curves
that are 100% modulated on periods of 569 and 321 seconds respectively. These
periods and no others are also seen at optical and infra-red wavelengths. These
properties have led to the suggestion that the periods are the orbital period
of ultra-compact pairs of white dwarfs. There are two main double white dwarf
models: the unipolar inductor model analogous to the Jupiter-Io system and the
direct impact model analogous to Algol. In this paper we consider geometrical
constraints on the unipolar inductor model, in particular what parameter values
(component masses, orbital inclination and magnetic co-latitude) can describe
the X-ray and optical light curves. We find that for a dipole field on the
primary star, the unipolar inductor model fails to match the data on V407 Vul
for any combination of parameters, and can only match RX 0806.3+1527 if the
sparser set of observations of this star have been unluckily timed.


title: Infrared luminosities of galaxies in the Local Volume

abstract:
  Near-infrared properties of 451 galaxies with distances D \leq 10 Mpc are
considered basing on the all-sky two micron survey (2MASS). A luminosity
function of the galaxies in the K-band is derived within [-25,-11] mag. The
local (D < 8 Mpc) luminosity density is estimated to be 6.8*10^8 L_sun/Mpc^3
that exceeds (1.5+-0.1) times the global cosmic density in the K-band. Virial
mass-to-K-luminosity ratios are determined for nearby groups and clusters. In
the luminosity range of (5*10^{10} - 2*10^{13})L_sun, the groups and clusters
follow the relation \lg(M/L_K) propto (0.27+-0.03) lg(L_K) with a scatter of
\~0.1 comparable to errors of the observables. The mean ratio <M/L_K> ~=
(20-25) M_sun/L_sun for the galaxy systems turns out to be significantly lower
than the global ratio, (80-90)M_sun/L_sun, expected in the standard
cosmological model with the matter density of Omega_m =0.27. This discrepancy
can be resolved if most of dark matter in the universe is not associated with
galaxies and their systems.


title: Effects of dynamical evolution on the distribution of substructures

abstract:
  We develop a semi-analytical model that determines the evolution of the mass,
position and internal structure of dark matter substructures orbiting in dark
matter haloes. We apply this model to the case of the Milky Way. We focus in
particular on the effects of mass loss, dynamical friction and
substructure--substructure interactions, the last of which has previously been
ignored in analytic models of substructure evolution. Our semi-analytical
treatment reproduces both the spatial distribution of substructures and their
mass function as obtained from the most recent N-body cosmological calculations
of Gao et al. (2004). We find that, if mass loss is taken into account, the
present distribution of substructures is practically insensitive to dynamical
friction and scatterings from other substructures.
  Implementing these phenomena leads to a slight increase (~5%) in the number
of substructures at r<0.35 r_vir, whereas their effects on the mass function
are negligible. We find that mass loss processes lead to the disruption of
substructures before dynamical friction and gravitational scattering can
significantly alter their orbits. Our results suggest that the present
substructure distribution at r>0.35 r_vir reflects the orbital properties at
infall and is, therefore, purely determined by the dark matter environment
around the host halo and has not been altered by dynamical evolution.


title: The quest for cosmic ray protons in galaxy clusters

abstract:
  There have been many speculations about the presence of cosmic ray protons
(CRps) in galaxy clusters over the past two decades. However, no direct
evidence such as the characteristic gamma-ray signature of decaying pions has
been found so far. These pions would be a direct tracer of hadronic CRp
interactions with the ambient thermal gas also yielding observable synchrotron
and inverse Compton emission by additionally produced secondary electrons. The
obvious question concerns the type of galaxy clusters most likely to yield a
signal: Particularly suited sites should be cluster cooling cores due to their
high gas and magnetic energy densities. We studied a nearby sample of clusters
evincing cooling cores in order to place stringent limits on the cluster CRp
population by using non-detections of EGRET. In this context, we examined the
possibility of a hadronic origin of Coma-sized radio halos as well as radio
mini-halos. Especially for mini-halos, strong clues are provided by the very
plausible small amount of required CRp energy density and a matching radio
profile. Introducing the hadronic minimum energy criterion, we show that the
energetically favored CRp energy density is constrained to 2% +/- 1% of the
thermal energy density in Perseus. We also studied the CRp population within
the cooling core region of Virgo using the TeV gamma-ray detection of M 87 by
HEGRA. Both the expected radial gamma-ray profile and the required amount of
CRp support this hadronic scenario.


title:
Empirical constraints on the GR electric field associated with PSR
  J0437-4715

abstract:
  We simulate the magnetosphere of the nearby millisecond pulsar PSR
J0437-4715, which is expected to have an unscreened electric potential due to
the lack of magnetic pair production. We incorporate General Relativistic (GR)
effects and study curvature radiation (CR) by primary electrons, but neglect
inverse Compton (IC) scattering of thermal X-ray photons by these electrons. We
find that the CR spectrum cuts off at energies below ~ 17 GeV, well below the
threshold of the H.E.S.S. telescope <~ 100 GeV, while other models predict a
much higher cutoff of >~ 100 GeV. GR theory also predicts a relatively narrow
pulse of ~ 0.2 phase width centered on the magnetic axis. EGRET observations
above 100 MeV significantly constrain the application of the Muslimov & Harding
(1997) model for gamma-ray production as a result of GR frame dragging, and
ultimately its polar cap (PC) current and accelerating potential. Whereas the
standard prediction of this pulsar's gamma-ray luminosity due to GR frame
dragging is ~10% of the spindown power, a non-detection by forthcoming H.E.S.S.
observations will constrain it to <~ 0.3%, enforcing an even more severe
revision of the accelerating electric field and PC current.


title: XMM-Newton detection of type I X-ray bursts in M 31

abstract:
  We searched for X-ray bursts in XMM-Newton archival data of X-ray sources in
M 31 globular clusters (GCs) and GC candidates. We detected two bursts
simultaneously in EPIC pn and MOS detectors and some more candidates in EPIC
pn. The energy distribution of the burst photons and the intrinsic luminosity
during the peak of the bursts indicate that at least the strongest burst was a
type I radius expansion burst. The bursts identify the sources as neutron star
low mass X-ray binaries in M 31. The type I X-ray bursts in M 31 are the first
detected outside the Milky Way and show that with the help of XMM-Newton X-ray
bursts can be used to classify neutron star low mass X-ray binaries in Local
Group galaxies.


title: Infrared emission in radio galaxy NGC 4261

abstract:
  We have analyzed the total and nuclear SED for NGC 4261 and find that the
dominant process for the mid- and far-infrared emission in this object is
non-thermal emission from the active nucleus. Modeling the emission from the
optically detected 300 pc dust disk yields no significant disk contribution at
any wavelength. To explain the observations, either the disk has an inflated
inner region which partly absorbs the core, or the intrinsic core spectrum is
curved. The inner 10 pc of the disk can potentially be conceived as an
obscuring torus, albeit with optical depth around unity.


title:
GaBoDS: The Garching-Bonn Deep Survey - III. Lyman-Break Galaxies in the
  Chandra Deep Field South

abstract:
  We present first results of our search for high-redshift galaxies in deep CCD
mosaic images. As a pilot study for a larger survey, very deep images of the
Chandra Deep Field South (CDFS), taken withWFI@MPG/ESO2.2m, are used to select
large samples of 1070 U-band and 565 B-band dropouts with the Lyman-break
method. The data of these Lyman-break galaxies are made public as an electronic
table. These objects are good candidates for galaxies at z~3 and z~4 which is
supported by their photometric redshifts. The distributions of apparent
magnitudes and the clustering properties of the two populations are analysed,
and they show good agreement to earlier studies. We see no evolution in the
comoving clustering scale length from z~3 to z~4. The techniques presented here
will be applied to a much larger sample of U-dropouts from the whole survey in
near future.


title:
The Highest-Energy Photons Seen by the Energetic Gamma Ray Experiment
  Telescope (EGRET) on the Compton Gamma Ray Observatory

abstract:
  During its nine-year lifetime, the Energetic Gamma Ray Experiment Telescope
(EGRET) on the Compton Gamma Ray Observatory (CGRO) detected 1506 cosmic
photons with measured energy E>10 GeV. Of this number, 187 are found within 1
degree of sources that are listed in the Third EGRET Catalog and were included
in determining the detection likelihood, flux, and spectra of those sources. In
particular, five detected EGRET pulsars are found to have events above 10 GeV,
and together they account for 37 events. A pulsar not included in the Third
EGRET Catalog has 2 events, both with the same phase and in one peak of the
lower-energy gamma-ray light-curve. Most of the remaining 1319 events appear to
be diffuse Galactic and extragalactic radiation based on the similarity of the
their spatial and energy distributions with the diffuse model and in the E>100,
MeV emission. No significant time clustering which would suggest a burst was
detected.


title: Models of Accreting Gas Giant Protoplanets in Protostellar Disks

abstract:
  (Abridged) We consider models of gas giant planets forming in protoplanetary
disks consisting of solid cores with gaseous envelopes in contact with their
critical Hill spheres while accreting gas from the surrounding disk.We suppose
the luminosity derives from gas accretion alone.We label such models as type A
and follow their evolution which may occur on a time scale similar to the
protostellar disk lifetime until rapid gas accretion. We consider another set
of models, we label type B, with a free surface, powered by gravitational
contraction, while accreting through a disk.We find these models rapidly attain
a radius <~ 2x10^(10)cm without subsequent expansion.We speculate that giant
planet formation is initially described by models of type A, until at the onset
of rapid gas accretion, there is a transition to models of type B. Protoplanet
migration in standard models tends to be most effective near this transition
where it also changes from type I to type II.If a mechanism prevents type I
migration of low mass protoplanets, a rapid inward migration might occur near
the transitional mass regime. Such protoplanets would end up in the inner disk
regions undergoing type II migration and further accretion potentially becoming
sub Jovian close orbiting planets. Noting that dustier more massive cores spend
longer at a larger transitional mass where faster migration is expected, these
may be more prone to end in close orbiters.We find the luminosity of the
protoplanets during the later stages is dominated by the circumplanetary disk
and protoplanet disk boundary layer.For one Jupiter mass the luminosity range
is 10^-(1.5-4) L_sun$ depending on the evolutionary stage and external
conditions.


title:
A Mass Measurement for the Missing Baryons in the Warm-Hot Intergalactic
  Medium via the X-ray Forest

abstract:
  Recent Cosmological measurements indicate that baryons comprise about four
percent of the total mass-energy density of the Universe, which is in accord
with the predictions arising from studies of the production of the lightest
elements. It also is in agreement with the actual number of baryons detected at
early times (redshifts>2). However, close to our own epoch (z<2), the number of
baryons actually detected add up to just over half (~55 percent) of the number
seen at z>2, meaning that about 45 percent are 'missing'. Here we report a
determination of the mass-density of a previously undetected population of
baryons, in the warm-hot phase of the intergalactic medium. We show that this
mass-density is consistent, within the uncertainties, with the mass-density of
the missing baryons.


title: Continuous star formation in gas-rich dwarf galaxies

abstract:
  Blue Compact Dwarf and Dwarf Irregular galaxies are generally believed to be
unevolved objects, due to their blue colors, compact appearance and large gas
fractions. Many of these objects show an ongoing intense burst of star
formation or have experienced it in the recent past. By means of 2-D
hydrodynamical simulations, coupled with detailed chemical yields originating
from SNeII, SNeIa and intermediate-mass stars, we study the dynamical and
chemical evolution of model galaxies with structural parameters similar to
IZw18 and NGC1569. Bursts of star formation with short duration are not able to
account for the chemical and morphological properties of these galaxies. The
best way to reproduce the chemical composition of these objects is by assuming
long-lasting episodes of star formation and a more recent burst, separated from
the previous episodes by a short quiescent period. The last burst of star
formation, in most of the explored cases, does not affect the chemical
composition of the galaxy observable in HII regions, since the enriched gas
produced by young stars is in a too hot phase to be detectable with the optical
spectroscopy.


title: The cosmic saga of 3He

abstract:
  We recall the emergence of the ``3He problem'', its currently accepted
solution, and we summarize the presently available constraints on models of
stellar nucleosynthesis and studies of Galactic chemical evolution from
measurements of the abundance of 3He in the Galaxy.


title:
FUSE Observations of Interstellar and Intergalactic Absorption Toward
  the X-ray Bright BL Lac Object Mrk 421

abstract:
  High-quality Far-Ultraviolet Spectroscopic Explorer (FUSE) observations at 20
km /s resolution of interstellar and intergalactic absorption from 910 to 1187
A are presented for the X-ray bright BL Lac object Mrk 421. In this study we
consider the O VI absorption between -140 to 165 km /s and its relationship to
the lower ionization absorption and to the strong absorption produced by O VII
and O VIII at X-ray wavelengths. The O VI absorption extending from -140 to 60
km /s is associated with strong low ionization gas absorption and originates in
the Galactic thick disk / halo. This O VI appears to be produced by a
combination of processes, including conductive interfaces between warm and hot
gas and possibly cooling Galactic Fountain gas and hot halo gas bubbles. The O
VI absorption extending from 60 to 165 km /s has unusual ionization properties
in that there is very little associated low ionization absorption, with the
exception of C III. This absorption is not observed toward two foreground halo
stars, implying that it occurs in gas more distant than 3.5 kpc from the
Galactic disk. Over the 60 to 165 km/s velocity range, O VI and C III
absorption have the same kinematic behavior. N(O VI)/N(C III) = 10+/-3 over the
60 to 120 km/s velocity range. Given the association of O VI with C III, it is
unlikely that the high velocity O VI co-exists with the hotter gas responsible
for the O VII and O VIII absorption. The O VI positive velocity absorption wing
might be tracing cooler gas entrained in a hot Galactic Fountain outflow. The O
VII and O VIII absorption observed by Chandra and XMM-Newton may trace the hot
gas in a highly extended (~100 kpc) Galactic corona or hot gas in the Local
Group.


title: Magnetic Fields in Core Collapse Supernovae: Possibilities and Gaps

abstract:
  Spectropolarimetry of core collapse supernovae has shown that they are
asymmetric and often, but not universally, bi-polar. The Type IIb SN1993J and
similar events showed large scatter in the Stokes parameter plane.
Observational programs clearly have much more to teach us about the complexity
of asymmetric supernovae and the physics involved in the asymmetry. Jet-induced
supernova models give a typical jet/torus structure that is reminiscent of some
objects like the Crab nebula, SN1987A and perhaps Cas A. Jets, in turn, may
arise from the intrinsic rotation and magnetic fields that are expected to
accompany core collapse. We summarize the potential importance of the
magneto-rotational instability for the core collapse problem and sketch some of
the effects that large magnetic fields, ~10^{15} G, may have on the physics of
the supernova explosion. Open issues in the problem of multi-dimensional
magnetic core collapse are summarized and a critique is given of some recent
MHD collapse calculations.


title:
VLBA Polarization Observations of Markarian 421 After a Gamma-Ray High
  State

abstract:
  We present four high dynamic range, dual-circular polarization, Very Long
Baseline Array (VLBA) observations at 22 GHz of Markarian 421, taken throughout
the year following the source's unprecedented gamma-ray high state in early
2001. These four new VLBA observations are combined with data from our earlier
1999 paper and archival VLBA data-sets that have become available since 1999 to
produce a combined 28 epoch VLBA data-set on Mrk 421 spanning the years 1994 to
2002. No new component associated with the 2001 flares was seen on the total
intensity images, but the combined data-set allowed precise measurements of the
apparent speeds of the existing components. The peak measured apparent speed
was for component C5, which has an apparent speed of 0.1 +/- 0.02 c (H_0=71 km
s^{-1} Mpc^{-1}, Omega_m=0.27, and Omega_Lambda=0.73). No counterjet is seen
with a limit on the jet to counterjet brightness ratio J >~ 100. These observed
VLBI properties of Markarian 421 are consistent with a jet with a bulk Lorentz
factor of about 2 and an angle to the line-of-sight of about 1 degree,
suggesting a jet that decelerates between the gamma-ray producing region and
the parsec scale. The VLBI core and inner jet (component C7) have fractional
polarizations of about 5%, and an electric vector position angle (EVPA) aligned
with the jet axis. Component C5 (at 1.5 mas from the core) has a higher
fractional polarization of about 15%, and an EVPA nearly orthogonal to the jet
axis. Significant variability is detected in the EVPA of component C6, which at
two of the four epochs shows an EVPA aligned with the jet axis, possibly a sign
of propagating disturbances that are only visible on the polarization images.
If these propagating disturbances are linked to the 2001 gamma-ray high state,
then their inferred apparent speed is between 1 and 3 c.


title: The Absorption Signature of Six MgII-Selected Systems Over 0.5<z<0.9

abstract:
  We present the following results of photoionization modeling of six
MgII-selected absorption systems, at redshift 0.5 < z 0.9, along lines of sight
toward three quasars: PG 1241+176, PG 1248+401, and PG 1317+274. These are part
of a larger sample of ~20 MgII absorbers at intermediate redshift, that
facilitates a survey of the properties of, and processes active in, the
multiple phases of gas, both in and outside of galaxies. We present new high
resolution ultraviolet spectra from HST/STIS as well as high resolution optical
spectra obtained with HIRES/Keck. Together, these spectra allow simultaneous
study of a variety of ionization states of different chemical elements, with
resolution of the kinematics providing strong constraints on multiphase
properties. The six systems presented here include several that are likely to
arise from lines of sight through disk and halo structures of spiral galaxies.
For these we find that the high ionization gas, traced by CIV is consistent
with coronal structures that resemble that of the Milky Way, along with high
velocity clouds at 100-200 km/s. Another system has relatively weak CIV,
relative to the low ionization absorption, which leads to a discussion of the
circumstances in which a corona might be weak or absent in a galaxy, i.e. an
early-type morphology or low star formation rate. Finally, we present systems
that are examples of single-cloud and multiple-cloud weak MgII absorbers, which
are as a class not likely to be within ~50 kpc of luminous galaxies. Based the
physical conditions inferred from models, we discuss the nature of these types
of systems, which may trace outer regions of galaxies, dwarf galaxy satellites,
or metal-rich regions of the intergalactic medium.


title: What do loose groups tell us about galaxy formation?

abstract:
  We present the results of a Parkes Multibeam HI survey of six loose groups of
galaxies analogous to the Local Group. This survey was sensitive to HI-rich
objects in these groups to below 10^7 M(sun) of HI, and was designed to search
for low mass, gas-rich satellite galaxies and potential analogs to the
high-velocity clouds seen around the Milky Way. This survey detected a total of
79 HI-rich objects associated with the six groups, half of which were new
detections. While the survey identified a small number of dwarf galaxies, no
star-free HI clouds were discovered. The HI mass function of the six groups
appears to be roughly flat as is that of the Local Group. The cumulative
velocity distribution function (CVDF) of the HI-rich halos in the six groups is
identical to that of the Local Group. Both of these facts imply that these
groups are true analogs to the Local Group and that the Local Group is not
unique in its lack of low-mass dwarf galaxies as compared to the predictions of
cold dark matter models of galaxy formation. This survey also constrains the
distance to and HI masses of the compact high-velocity clouds (CHVCs) around
the Milky Way. The lack of CHVC analog detections implies that they are
distributed within <160 kpc of the Milky Way and have average HI masses of
<4x10^5 M(sun). The spatial distribution of CHVCs is consistent with the
predictions of simulations for dark matter halos. Furthermore the CVDF of Local
Group galaxies plus CHVCs matches the predicted CVDF of cold dark matter
simulations of galaxy formation. This provides circumstantial evidence that
CHVCs may be associated with low-mass dark matter halos.


title:
Searching for White and Brown Dwarfs in the frame of the MUSYC/CYDER
  survey

abstract:
  MUSYC (MUltiwavelength Survey by Yale and Chile), and its predecessor, the
CYDER (Cal'an Yale Deep Extragalactic Research) survey are both deep
multiwavelength surveys mainly aiming at extragalactic issues; however they
were both designed with a strong Galactic component in mind. Therefore they
consist not only of multipassband imaging (UBVRIzJK) and wide field multi
object spectroscopy - it is also foreseen to create a multi-epoch dataset, thus
allowing proper motions to be derived using data of 1 and 4-5 years baseline.
This enables us to identify fast moving objects, and derive tangential
velocities of nearby and intrinsically faint objects, such as White Dwarfs
(especially cool WDs) and Brown Dwarfs (BDs). For the former, we will be able
to study the faint end of the halo-field luminosity function and determine the
fraction of baryonic dark matter consisting of WDs. We will be able to put
constraints on the volume density of BDs, and determine whether this density
actually meets expectations. Here we give a report of work in progress.


title: Carbon Monoxide in low-mass dwarf stars

abstract:
  We compare high resolution infrared observations of the CO 3-1 bands in the
2.297-2.310 micron region of M dwarfs and one L dwarf with theoretical
expectations. We find a good match between the observational and synthetic
spectra throughout the 2000-3500K temperature regime investigated. Nonetheless,
for the 2500-3500 K temperature range the temperatures that we derive from
synthetic spectral fits are higher than expected from more empirical methods by
several hundred K. In order to reconcile our findings with the empirical
temperature scale it is necessary to invoke warming of the model atmosphere
used to construct the synthetic spectra. We consider that the most likely
reason for the back-warming is missing high temperature opacity due to water
vapour. We compare the water vapour opacity of the Partridge & Schwenke (1997)
line list used for the model atmosphere with the output from a preliminary
calculation by Barber & Tennyson (2004). While the Partridge & Schwenke line
list is a reasonable spectroscopic match for the new line list at 2000 K, by
4000 K it is missing around 25% of the water vapour opacity. We thus consider
that the offset between empirical and synthetic temperature scales is explained
by the lack of hot water vapour used for computation of the synthetic spectra.
For our coolest objects with temperatures below 2500 K we find best fits when
using synthetic spectra which include dust emission. Our spectra also allow us
to constrain the rotational velocities of our sources, and these velocities are
consistent with the broad trend of rotational velocities increasing from M to
L.


title:
Probing the nuclear obscuration in radio-galaxies with near infrared
  imaging

abstract:
  We present the first near-infrared (K'-band) homogeneous observations of a
complete sub-sample of the 3CR radio catalogue comprising all High Excitation
Galaxies (HEGs) at z<0.3. After showing that the surface brightness
decomposition technique to measure central point-like sources is affected by
significant uncertainties for the objects in the studied sample, we present a
new, more accurate method based on the R-K' color profile. Via this method we
find a substantial nuclear K'-band excess in all but two HEGs -- most likely
directly associated to their nuclear emission -- and we measure the
corresponding 2.12 $\mu$m nuclear luminosities. Within the frame of the
unification scheme for radio-loud active galactic nuclei, it appears that
obscuration alone is not able to account for the different nuclear properties
of the majority of the HEGs and Broad Line Radio Galaxies (BLRGs), and also
scattering of the (optically) hidden nuclear light from a compact region must
be invoked. More precisely, for ~70% of the HEGs the observed point-like
optical emission is dominated by the scattered component, while in the K'-band
both scattered and direct light passing through the torus contribute to the
observed nuclear luminosity. The estimated fraction of scattered light ranges
from a few tenths to a few percent, while the torus extinction is between
15<A_{V,torus}<50 mag with only a few exceptions with lower obscuration.


title:
Spectroscopy of Red Giants in the LMC Bar: Abundances, Kinematics, and
  the Age-Metallicity Relation

abstract:
  We report metallicities and radial velocities derived from spectra at the
near-infrared calcium triplet for 373 red giants in a 200 square arcminute area
at the optical center of the LMC bar. These are the first spectroscopic
abundance measurements of intermediate-age and old field stars in the high
surface brightness heart of the LMC. The metallicity distribution is sharply
peaked at the median value [Fe/H] = -0.40, with a small tail of stars extending
down to [Fe/H] <= -2.1; 10% of the red giants are observed to have [Fe/H] <=
-0.7. The relative lack of metal-poor stars indicates that the LMC has a "G
dwarf" problem, similar to the Milky Way. The abundance distribution can be
closely approximated by two Gaussians containing 89% and 11% of the stars,
respectively: the first component is centered at [Fe/H] = -0.37 with standard
deviation = 0.15, and the second at [Fe/H] = -1.08 with standard deviation =
0.46. Because of the central location of our field, kinematic constraints are
not strong, but there is no evidence that the bar deviates from the general
motion of the LMC disk. The velocity dispersion of the whole sample is 24.7 +/-
0.4 km/sec. The most metal-poor 5% of stars ([Fe/H] < -1.15) show a dispersion
of 40.8 +/- 1.7 km/sec, more than twice the value for the most metal-rich 5%.
The age-metallicity relation (AMR) is almost flat during the period from 5-10
Gyr ago, with an apparent scatter of +/-0.15 dex about the mean metallicity for
a given age. (abstract abridged)


title: X-ray spectra of XMM-Newton serendipitous medium flux sources

abstract:
  We report on the results of a detailed analysis of the X-ray spectral
properties of a large sample of sources detected serendipitously with the
XMM-Newton observatory in 25 selected fields. The survey covers a total solid
angle of ~3.5 deg2 and contains 1137 sources with ~10E-15 < S0.5-10 < 10E-12
erg cm-2 s-1. We find evidence for hardening of the average X-ray spectra of
the sources towards fainter fluxes. We interpret this as indicating a higher
degree of photoelectric absorption amongst the fainter population. Absorption
is detected at 95% confidence in 20% of the sources, but it could certainly be
present in many other sources below our detection capabilities. For Broad Line
AGNs (BLAGNs), we detect absorption in ~10% of the sources with column
densities in the range 10E21 - 10E22 cm-2. The fraction of absorbed Narrow
Emission Line galaxies (NELGs, most with intrinsic X-ray luminosities >10E43
erg s-1, and therefore classified as type 2 AGNs) is significantly higher
(40%), with a hint of moderately higher columns. We do not find evidence for a
redshift evolution of the underlying power law index of BLAGNs, which stays
roughly constant at Gamma ~1.9, with intrinsic dispersion of 0.4. A small
fraction (~7%) of BLAGNs and NELGs require the presence of a soft excess, that
we model as a black body with temperature ranging from 0.1 to 0.3 keV.
Comparing our results on absorption to popular X-ray background synthesis
models, we find absorption in only ~40% of the sources expected. This is due to
a deficiency of heavily absorbed sources (with NH ~10E22 - 10E24 cm-2) in our
sample in comparison with the models. We therefore conclude that the synthesis
models require some revision in their specific parameters.


title:
Clues on the Structure and Composition of Galactic Disks from Studies of
  "Superthin" Spirals: the Case of UGC3697

abstract:
  We summarize results from an HI+optical imaging study of the ``Integral
Sign'' galaxy, UGC3697. UGC3697 is a low-mass, Sd spiral that exhibits a
``superthin'' disk morphology despite a prounced gasous and stellar warp. Our
new observations show evidence for a recent minor merger in this system that
could account for its large-scale warp and a number of other properties of this
galaxy. We speculate that UGC3697 has been caught in a rather short-lived
dynamical state, and may soon undergo significant structural and morphological
changes.


title:
Preliminary Observational Results of Tidal Synchronization in Detached
  Solar-Type Binary Stars

abstract:
  We present preliminary observational results on tidal synchronization in
detached solar-type binary stars in the open clusters M35 (NGC2168; ~ 150 Myr)
and M34 (NGC1039; ~ 250 Myr). M35 and M34 provide populations of close
late-type binaries with ages that make them attractive observational tests of
models of tidal synchronization during the early main-sequence phase. A
combined dataset of stellar rotation periods from time-series photometry and
binary orbital periods and eccentricities from time-series spectroscopy enables
us to determine the angular rotation velocity of the primary star and the
orbital angular velocity at periastron. Comparison of the stellar and orbital
angular velocities provides information about the level of synchronization in
individual binary stars.


title:
Determining the grain composition of the interstellar medium with high
  resolution X-ray spectroscopy

abstract:
  We investigate the ability of high resolution X-ray spectroscopy to directly
probe the grain composition of the interstellar medium. Using iron K-edge
experimental data of likely ISM dust candidates taken at the National
Synchrotron Light Source at Brookhaven National Laboratory and the Advanced
Photon Source at Argonne National Laboratory, we explore the prospects for
determining the chemical composition of astrophysical dust and discuss a
technique for doing so. Focusing on the capabilities of the AstroE2 XRS
micro-calorimeters, we assess the limiting effects of spectral resolution and
noise for detecting significant X-ray absorption fine structure signal in
astrophysical environments containing dust. We find that given sufficient
signal, the resolution of the XRS will allow us to definitively distinguish gas
from dust phase absorption, and certain chemical compositions.


title: The 2-850 micron SED of starforming galaxies

abstract:
  We present preliminary results on a study of the 2--850 micron SEDs of a
sample of 30 FIRBACK galaxies selected at 170 micron. These sources are
representative of the brightest ~10% of the Cosmic Infrared Background. They
are a mixture of mostly local (z<~0.3) starforming galaxies, and a tail of
ULIGs that extend up to z~1, and are likely to be a similar population to faint
SCUBA sources. We use archival Spitzer IRAC and MIPS data to extend the
spectral coverage to the mid-IR regime, resulting in an unprecended (for this
redshift range) census of their infrared SEDs. This allows us to study in far
greater detail this important population linking the near-IR stellar emission
with PAH and thermal dust emission. We do this using a Markov Chain Monte Carlo
method, which easily allows for the inclusion of ~6 free parameters, as well as
an estimate of parameter uncertainties and correlations.


title: Atmospheric neutrino challenges

abstract:
  We briefly review the improvements in the predictions of atmospheric neutrino
fluxes since the NOW2000 workshop. In spite of the great progress in
calculational technique the predictions are still not exact because of the
uncertainties in the two major sets of input - cosmic ray flux and hadronic
interactions on light nuclei.


title: COSMIC : Microarcsecond resolution with a 30 metre radio telescope

abstract:
  Interstellar scintillation has been conclusively demonstrated to be the
principal cause of the intraday variability (IDV) observed in the
centimetre-wavelength emission of many AGN. A few sources show large amplitude
modulation in their flux density on a timescale of hours. However, the majority
of IDV sources exhibit variability on timescales of a day or more. On
timescales of a year some sources have been found to show an annual cycle in
the pattern of their variability. Such an annual cycle occurs because the
relative speeds of the Earth and the interstellar medium change as the Earth
orbits the Sun. To search for these annual variations as well as to follow the
source evolution, requires a dedicated instrument; the necessary amounts of
observing time are beyond the capability of the national facility instruments.
Here we describe the scientific motivation for, and present an outline of the
COSMIC (Continuous Single dish Monitoring of Intraday variability at Ceduna)
project which uses the University of Tasmania's 30 m diameter radio telescope
at Ceduna, which has been monitoring the flux density of a number of the
stronger southern scintillators at 6.65 GHz since March 2003.


title:
Estimating the Correlation Length r_0 from the Number of Galaxy Pairs
  with Similar Redshifts

abstract:
  We discuss methods that can be used to estimate the spatial correlation
length r_0 of galaxy samples from the observed number of pairs with similar
redshifts. The standard method is unnecessarily noisy and can be compromised by
errors in the assumed selection function. We present three alternatives, one
less noisy, one that responds differently to systematic errors, the third
insensitive to the selection function, and quantify their performance by
applying them to a cosmological N-body simulation and to the Lyman-break survey
of galaxies at redshift z~3. Researchers adopting the standard method could
easily conclude that the Lyman-break galaxy comoving correlation length was r_0
\~ 11 Mpc/h, several times larger than the correct value. The use of our
proposed methods would make this error impossible, except in the small sample
limit. When N_gal<~20, major errors in estimates of r_0 occur alarmingly often.


title:
The Metallicity of Post-T Tauri Stars: A preliminary approach to the
  understanding of the metal enrichment of stars harboring planets

abstract:
  The metallicity of young low mass Post-T Tauri stars in coeval associations
is practically unknown. This work is the beginning of a systematic measurement
of these metallicities based on high resolution spectra of low rotating members
of these associations. Here, we present an application by examining the
behavior of the Iron abundance with stellar mass and temperature of some
members of an association 30 Myr old. This will test the possibility of
explaining the high metallic content of stars with planets by means of
injection of planetesimals during this early stage of evolution.