title: What is the origin of the soft excess in AGN?

abstract:
  We investigate the nature of the soft excess below 1 keV observed in AGN. We
use the XMM-Newton data of the low redshift, optically bright quasar, PG
1211+143, and we compare it with the Narrow Line Seyfert 1 galaxy, 1H 0707-495,
which has one of the strongest soft excesses seen. We test various ideas for
the origin of the soft X-ray excess, including a separate spectral component
(for example, low temperature Comptonized emission), a reflection-dominated
model, or a complex absorption model. All three can give good fits to the data,
and chi^2 fitting criteria are not sufficient to discriminate among them.
Instead, we favour the complex absorption model on the grounds that it requires
less extreme parameters. In particular the geometry appears to be more
physically plausible as the reflected component in the smeared absorption model
is no longer dominant, and relativistic distortions, while still clearly
present, are not tremendously larger than expected for a disc around a
Schwarzchild black hole.


title:
Pulsation properties of the $\beta$ Cephei star SY Equ from combined
  photometric and spectroscopic data

abstract:
  We present the analysis of simultaneous multicolour $uvyI_{\rm C}$ photometry
and low-resolution spectroscopy for the rapidly rotating $\beta$ Cephei star SY
Equ. From the photometric time series, we confirm the dominant pulsation
frequency, $f_1$ = 6.029 d$^{-1}$, and we find an evidence for two additional
modes. In spectroscopy, the highest peak occurs at $f_{\rm a}$ = 0.197 d$^{-1}$
or its alias 0.803 d$^{-1}$. It can be interpreted either in terms of a binary
motion or as the $g$-mode pulsation. In addition, we reveal the pulsation mode
with frequency of about 6.029 d$^{-1}$, i.e. the same which dominates
photometric variations, and a few new candidates. For the dominant frequency we
obtain mode identification from the combined photometric and spectroscopic
observations. From non-adiabatic pulsation calculations, we show that the
frequency of the dominant mode in SY Equ is consistent with the stellar models
of much lower effective temperatures than used in many papers.


title: The properties of V838 Mon in 2002 November

abstract:
  We present the results of modelling the 0.45--1 micron spectral energy
distribution of V838 Mon for 2002 November. Synthetic spectra were calculated
using the NextGen model atmospheres of Hauschildt et al. (1999), which
incorporate line lists for H2O, TiO, CrH, FeH, CO, and MgH, as well as the VALD
atomic line list. Fits to the observed spectra show that, in 2002 November, the
effective temperature of V838 Mon was approximately 2000 +/-100 K. Our
theoretical spectra show a comparatively weak dependence on log g. Preliminary
analysis of the hot star observed together with V838 Mon shows it to be a
normal B3V dwarf.


title: Charge-Transfer induced EUV and Soft X-ray emissions in the Heliosphere

abstract:
  We study the EUV/soft X-ray emission generated by charge transfer between
solar wind heavy ions and interstellar H and He neutral atoms in the inner
Heliosphere. We present heliospheric maps and spectra for stationary solar
wind, depending on solar cycle phase, solar wind anisotropies and composition,
line of sight direction and observer position. A time-dependant simulation of
the X-ray intensity variations due to temporary solar wind enhancement is
compared to XMM Newton recorded data of the Hubble Deep Field North observation
(Snowden et al. 2004). Results show that the heliospheric component can explain
a large fraction of the line intensity below 1.3 keV, strongly attenuating the
need for soft X-ray emission from the Local Interstellar Bubble.


title: The search for the origin of the Local Bubble redivivus

abstract:
  We present a new unbiased search and analysis of all B stars in the solar
neighbourhood (within a volume of 400 pc diameter) using the Arivel data base
to track down the remains of the OB associations, which hosted the supernovae
responsible for the Local Bubble in the interstellar gas. We find after careful
dereddening and by comparison with theoretical isochrones, that besides the
Upper Scorpius the Upper Centaurus Lupus and Lower Centaurus Crux subgroups are
the youngest stellar associations in the solar neighbourhood with ages of 20 to
30 Myr, in agreement with previous work. In search for the ``smoking gun'' of
the origin of the Local Bubble, we have traced the paths of the associations
back into the past and found that they entered the present bubble region 10 to
15 Myr ago. We argue that the Local Bubble began to form then and estimate that
14 to 20 supernovae have gone off since. It is shown that the implied energy
input is sufficient to excavate a bubble of the presently observed size.


title: CMB signal in WMAP 3yr data with FastICA

abstract:
  We present an application of the fast Independent Component Analysis
(FastICA) to the WMAP 3yr data with the goal of extracting the CMB signal. We
evaluate the confidence of our results by means of Monte Carlo simulations
including CMB, foreground contaminations and instrumental noise specific of
each WMAP frequency band. We perform a complete analysis involving all or a
subset of the WMAP channels in order to select the optimal combination for CMB
extraction, using the frequency scaling of the reconstructed component as a
figure of merit. We found that the combination KQVW provides the best CMB
frequency scaling, indicating that the low frequency foreground contamination
in Q, V and W bands is better traced by the emission in the K band. The CMB
angular power spectrum is recovered up to the degree scale, it is consistent
within errors for all WMAP channel combination considered, and in close
agreement with the WMAP 3yr results. We perform a statistical analysis of the
recovered CMB pattern, and confirm the sky asymmetry reported in several
previous works with independent techniques.


title: A Bayesian Kepler Periodogram detects a second planet in HD 208487

abstract:
  An automatic Bayesian Kepler periodogram has been developed for identifying
and characterizing multiple planetary orbits in precision radial velocity data.
The periodogram is powered by a parallel tempering MCMC algorithm which is
capable of efficiently exploring a multi-planet model parameter space. The
periodogram employs an alternative method for converting the time of an
observation to true anomaly that enables it to handle much larger data sets
without a significant increase in computation time. Improvements in the
periodogram and further tests using data from HD 208487 have resulted in the
detection of a second planet with a period of $909_{-92}^{82}$d, an
eccentricity of $0.37_{-0.20}^{0.26}$, a semi-major axis of
$1.87_{-0.14}^{0.13}$ AU and an $M \sin i = 0.45_{-0.11}^{0.13}$ M$_{\rm J}$.
The revised parameters of the first planet are period $= 129.8\pm 0.4$d,
eccentricity $= 0.20\pm 0.09$, semi-major axis $= 0.51\pm0.02$ AU and $M \sin i
= 0.41\pm0.05$ M$_{\rm J}$. Particular attention is paid to several methods for
calculating the model marginal likelihood which is used to compare the
probabilities of models with different numbers of planets.


title: ISO Mid-Infrared Spectroscopy of Galactic Bulge AGB Stars

abstract:
  To study the nature of Bulge AGB stars and in particular their circumstellar
dust, we have analysed mid-infrared spectra obtained with the ISOCAM CVF
spectrometer in three Bulge fields. The ISOCAM 5-16.5 micron CVF spectra were
obtained as part of the ISOGAL infrared survey of the inner Galaxy. A
classification of the shape of the 10 micron dust feature was made for each
case. The spectra of the individual sources were modelled using a radiative
transfer model. Different combinations of amorphous silicates and
aluminium-oxide dust were used in the modelling. Spectra were obtained for 29
sources of which 26 are likely to be Bulge AGB stars. Our modelling shows that
the stars suffer mass loss rates in the range of 10^{-8} - 5 x 10^{-7} Msun /
yr, which is at the low end of the mass-loss rates experienced on the Thermally
Pulsing AGB. The luminosities range from 1,700 to 7,700 Lsun as expected for a
population of AGB stars with Minit of 1.5 - 2Msun. In agreement with the
condensation sequence scenario, we find that the dust content is dominated by
Al_2O_3 grains in this sample of low mass-loss rate stars.


title:
The 10 $\mu$m infrared band of silicate dust: A laboratory study
  comparing the aerosol and KBr pellet techniques

abstract:
  The profile of the silicate 10 $\mu$m IR band contains important information
about the evolutional stage of dust in circumstellar environments and the
possible ongoing process of planetesimal formation. In order to extract this
information, the observed band profiles are compared with calculated or
laboratory-measured absorption cross sections of amorphous and crystalline
grains with different sizes and compositions. We present in this study the
first laboratory measurements of the 10 $\mu$m band profiles of nonembedded,
i.e. free-flying, particles of amorphous and crystalline Mg$_2$SiO$_4$ (with
two different particle shapes), amorphous and crystalline MgSiO$_3$, and
crystalline olivine. We compare the spectra with those measured on embedded
grains and discuss the potential of the new experimental method for comparison
with observed spectra, as well as for future studies of agglomeration and
surface manipulation of the grains.


title: Consistent estimates of (56)Ni yields for type Ia supernovae

abstract:
  We present (56)Ni mass estimates for seventeen well-observed type Ia
supernovae determined by two independent methods. Estimates of the (56)Ni mass
for each type Ia supernova are determined from (1) modeling of the late-time
nebular spectrum and (2) through the combination of the peak bolometric
luminosity with Arnett's rule. The attractiveness of this approach is that the
comparison of estimated (56)Ni masses circumvents errors associated with the
uncertainty in the adopted values of reddening and distance. We demonstrate
that these two methods provide consistent estimates of the amount of (56)Ni
synthesized. We also find a strong correlation between the derived (56)Ni mass
and the absolute B-band magnitude (M(B)). Spectral synthesis can be used as a
diagnostic to study the explosion mechanism. By obtaining more nebular spectra
the Nif--M(B) correlation can be calibrated and can be used to investigate any
potential systematic effects this relationship may have on the determination of
cosmological parameters, and provide a new way to estimate extra-galactic
distances of nearby type Ia supernovae.


title:
Mid-IR Observations of T Tauri stars: Probing the Star-Disk Connection
  in Rotational Evolution

abstract:
  We present mid-IR N-band $(\lambda_{eff} = 10.2\micron)$ photometry of a
carefully selected sample of T Tauri stars thought to be single from the
Taurus-Auriga molecular cloud. Infrared excesses in these stars are generally
attributed to circumstellar dust-disks. Combining observations at 2.16$\micron$
(K$_{s}$-band) and 10.2$\micron$ (N-band) we probe a region in the
circumstellar dust-disk from a few stellar radii through the terrestrial planet
zone (0.02-1.0AU). By analyzing the distribution of the $(K_{s}-N)$ color index
with respect to previously measured photometric rotation periods we investigate
what role circumstellar disks play in the rotational evolution of the central
star. The resulting positive correlation between these two variables is
consistent with the notion that a star-disk interaction facilitates the
regulation of angular momentum during the T Tauri stage. We also demonstrate,
how including non-single stars in such an analysis will \textit{weaken} any
correlation in the relation between $(K_{s}-N)$ color and period. To further
understand disk properties we also present SEDs for a few objects with new
ground based M-band $(\lambda_{eff} = 4.8\micron)$ and Q-band $(\lambda_{eff} =
20\micron)$ data and compare them to a geometrically thin, optically-thick disk
model.


title: Hypersonic Molecular Shocks in Star Forming Regions

abstract:
  Much emission from star forming regions is from shock-excited gas. Shocks in
molecular clouds are still not fully understood, as magnetic fields, dust and
chemistry all play significant roles. I review the history, physics and current
work in understanding these shocks, and in their possible use as diagnostics of
local conditions.


title:
Mid-Infrared Observations of Class I/Flat-Spectrum Systems in Six Nearby
  Molecular Clouds

abstract:
  We have obtained new mid-infrared observations of 65 Class I/Flat-Spectrum
(F.S.) objects in the Perseus, Taurus, Chamaeleon I/II, Rho Ophiuchi, and
Serpens dark clouds. We detected 45/48 (94%) of the single sources, 16/16
(100%) of the primary components, and 12/16 (75%) of the secondary/triple
components of the binary/multiple objects surveyed. The composite spectral
energy distributions (SEDs) for all of our sample sources are either Class I or
F.S., and, in 15/16 multiple systems, at least one of the individual components
displays a Class I or F.S. spectral index. However, the occurrence of mixed
pairings, such as F.S. with Class I, F.S. with Class II, and, in one case, F.S.
with Class III, is surprisingly frequent. Such behaviour is not consistent with
that of multiple systems among T Tauri stars (TTS), where the companion of a
classical TTS also tends to be a classical TTS, although other mixed pairings
have been previously observed among Class II objects. Based on an analysis of
the spectral indices of the individual binary components, there appears to be a
higher proportion of mixed Class I/F.S. systems (65-80%) than that of mixed
Classical/Weak-Lined TTS (25-40%), demonstrating that the envelopes of Class I/
F.S. systems are rapidly evolving during this evolutionary phase. We report the
discovery of a steep spectral index secondary companion to ISO-ChaI 97,
detected for the first time via our mid-infrared observations. In our previous
near- infrared imaging survey of binary/multiple Class I/F.S. sources, ISO-ChaI
97 appeared to be single. With a spectral index of Alpha >= 3.9, the secondary
component of this system is a member of a rare class of very steep spectral
index objects, those with Alpha > 3. Only three such objects have previously
been reported, all of which are either Class 0 or Class I.


title:
Variations in the D/H ratio of extended sightlines from FUSE
  observations

abstract:
  We use new FUSE data to determine the column densities of interstellar DI,
NI, OI, FeII, and H2 along the HD41161 and HD53975 sightlines. Together with
N(HI) from the literature (derived from Copernicus and IUE data) we derive D/H,
N/H, and O/H ratios. These high column density sightlines have both log
H(HI)>21.00 and allow us to probe gas up to 1300 pc. In particular these
sightlines allow us to determine the gas phase D/H ratio in a hydrogen column
density range, log N(H)>20.70, where the only five measurements available in
the literature yield a weighted average of D/H = (0.86 +/- 0.08)E-5. We find
D/H=(2.14+ 0.51 - 0.43)E-5 along the HD41161 sightline. This ratio is 3sigma
higher than the weighted mean D/H ratio quoted above, for sightlines with log
N(H)>20.70, while the D/H ratio for the HD53975 line of sight, D/H = (1.02
+0.23 -0.20)E-5, agrees within the 1sigma uncertainties. Our D/H measurement
along the HD 41161 sightline presents the first evidence of variations of D/H
at high N(H). Our result seems to indicate that either the long sightlines that
according to the deuterium depletion model are dominated by cold undisturbed
gas where deuterium would be depleted onto carbonaceous grains occur at higher
N(H) than previously thought or that the clumping of low D/H values in the
literature for the long sightlines has another explanation. In addition, the
relatively high signal-to-noise ratio of the HD41161 data allows us to place
constraints on the f-values of some neutral chlorine transitions, present in
the FUSE bandpass, for which only theoretical values are available.


title: The stellar content of the isolated transition dwarf galaxy DDO210

abstract:
  We use Subaru Suprime-Cam and VLT FORS1 photometry of the dwarf galaxy DDO210
to study the global stellar content and structural properties of a
transition-type galaxy (with properties intermediate between dwarf irregular
and dwarf spheroidal systems). This galaxy is sufficiently isolated that tidal
interactions are not likely to have affected its evolution in any way. The
colour-magnitude diagrams of DDO210 show a red giant branch (RGB) population
(with an RGB bump), a bright asymptotic giant branch population, a red clump,
young main sequence stars and blue-loop stars. The youngest stars formed within
the last 60 Myrs and have a distinct radial distribution compared to the main
population. Whereas the overall stellar spatial distribution and HI spatial
distribution are concentric, the young stars are offset from the center of
DDO210 and are coincident with a `dent' in the HI distribution. The implied
recent star formation rate required to form the young population is
significantly higher than the derived current star formation rate, by a factor
of > 10.
  Most of the stars in DDO210 are found in a red clump, and its mean I-band
magnitude suggests that the majority of stars in DDO210 have an average age of
4^{+2}_{-1} Gyr. Given this age, the colour of the RGB implies a mean
metallicity of [Fe/H] ~ -1.3. By comparing the shape of the red clump with
models for a variety of star formation histories, we estimate that an old (> 10
Gyr) stellar population can contribute ~ 20 - 30% of the stars in DDO210 at
most. The unusual star formation history of DDO210, its low mass estimate and
its isolated nature, provide insight into how star formation proceeds in the
lowest mass, unperturbed, dwarf galaxy haloes.


title:
Constraining black hole masses from stellar kinematics by summing over
  all possible distribution functions

abstract:
  When faced with the task of constraining a galaxy's potential given limited
stellar kinematical information, what is the best way of treating the galaxy's
unknown distribution function (DF)? Using the example of estimating black hole
(BH) masses, I argue that the correct approach is to consider all possible DFs
for each trial potential, marginalizing the DF using an infinitely divisible
prior. Alternative approaches, such as the widely used maximum penalized
likelihood method, neglect the huge degeneracies inherent in the problem and
simply identify a single, special DF for each trial potential.
  Using simulated observations of toy galaxies with realistic amounts of noise,
I find that this marginalization procedure yields significantly tighter
constraints on BH masses than the conventional maximum-likelihood method,
although it does pose a computational challenge which might be solved with the
development of a suitable algorithm for massively parallel machines. I show
that in practice the conventional maximum-likelihood method yields reliable BH
masses with well-defined minima in their chi^2 distributions, contrary to
claims made by Valluri, Merritt & Emsellem.


title: How Hot is the Wind from TW Hydrae?

abstract:
  It has recently been suggested that the winds from Classical T Tauri stars in
general, and the wind from TW Hya in particular, reaches temperatures of at
least 300,000 K while maintaing a mass loss rate of $\sim 10^{-11}$ \Msol
yr$^{-1}$ or larger. If confirmed, this would place strong new requirements on
wind launching and heating models. We therefore re-examine spectra from the
Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope and
spectra from the Far Ultraviolet Spectroscopic Explorer satellite in an effort
to better constrain the maximum temperature in the wind of TW Hya. We find
clear evidence for a wind in the \ion{C}{2} doublet at 1037 \AA and in the
\ion{C}{2} multiplet at 1335 \AA. We find no wind absorption in the \ion{C}{4}
1550 \AA doublet observed at the same time as the \ion{C}{2} 1335 \AA line or
in observations of \ion{O}{6} observed simultaneously with the \ion{C}{2} 1037
\AA line. The presence or absence of \ion{C}{3} wind absorption is ambiguous.
The clear lack of a wind in the \ion{C}{4} line argues that the wind from TW
Hya does not reach the 100,000 K characteristic formation temperature of this
line. We therefore argue that the available evidence suggests that the wind
from TW Hya, and probably all classical T Tauri stars, reaches a maximum
temperature in the range of 10,000 -- 30,000 K.


title: Time Domain Simulations of EMRIs using Finite Element Methods

abstract:
  This is a brief report on time-domain numerical simulations of
extreme-mass-ratio binaries based on finite element methods. We discuss a new
technique for solving the perturbative equations describing a point-like object
orbiting a non-rotating massive black hole and the prospects of using it for
the evaluation of the gravitational self-force responsible of the inspiral of
these binary systems. We also discuss the perspectives of transferring this
technology to the more astrophysically relevant case of a central rotating
massive black hole.


title:
Ultra High Energy Neutrinos in the Mediterranean: detecting nu_tau and
  nu_mu with a km^3 Telescope

abstract:
  We perform a study of the ultra high energy neutrino detection performances
of a km^3 Neutrino Telescope sitting at the three proposed sites for ANTARES,
NEMO and NESTOR in the Mediterranean sea. We focus on the effect of the
underwater surface profile on the total amount of yearly expected tau and mu
crossing the fiducial volume in the limit of full detection efficiency and
energy resolution. We also emphasize the possible enhancement of matter effect
by a suitable choice of the geometry of the Telescope.


title:
Unravelling Temporal Variability in Saturn's Spiral Density Waves:
  Results and Predictions

abstract:
  We describe a model that accounts for the complex morphology of spiral
density waves raised in Saturn's rings by the co-orbital satellites, Janus and
Epimetheus. Our model may be corroborated by future Cassini observations of
these time-variable wave patterns.


title:
Clues for the origin of the fundamental metallicity relations. I: The
  hierarchical building up of the structure

abstract:
  We analyse the evolutionary history of galaxies formed in a hierarchical
scenario consistent with the concordance $\Lambda$-CDM model focusing on the
study of the relation between their chemical and dynamical properties. Our
simulations consistently describe the formation of the structure and its
chemical enrichment within a cosmological context. Our results indicate that
the luminosity-metallicity (LZR) and the stellar mass-metallicity (MZR)
relations are naturally generated in a hierarchical scenario. Both relations
are found to evolve with redshift. In the case of the MZR, the estimated
evolution is weaker than that deduced from observational works by approximately
0.10 dex. We also determine a characteristic stellar mass, $M_c \approx 3
\times 10^{10} M_{\odot}$, which segregates the simulated galaxy population
into two distinctive groups and which remains unchanged since $z\sim 3$, with a
very weak evolution of its metallicity content. The value and role played by
$M_c$ is consistent with the characteristic mass estimated from the SDSS galaxy
survey by Kauffmann et al. (2004). Our findings suggest that systems with
stellar masses smaller than $M_c$ are responsible for the evolution of this
relation at least from $ z\approx 3$. Larger systems are stellar dominated and
have formed more than 50 per cent of their stars at $z \ge 2$, showing very
weak evolution since this epoch. We also found bimodal metallicity and age
distributions from $z\sim3$, which reflects the existence of two different
galaxy populations. Although SN feedback may affect the properties of galaxies
and help to shape the MZR, it is unlikely that it will significantly modify
$M_c$ since, from $z=3$ this stellar mass is found in systems with circular
velocities larger than $100 \kms$.


title: Optical Emission Band Morphologies of the Red Rectangle

abstract:
  We present narrow-band images of the Red Rectangle (RR) nebula which reveal
the distinct morphologies of this intriguing nebula in different optical
emission bands. The morphology of the RR nebula in blue luminescence (BL) and
extended red emission (ERE) are almost mutually exclusive. We also present the
optical detection of the circum-binary disk of the RR in the light of the BL.
The total intensities from the two optical band emissions (BL and ERE) when
summed over the nebula are of comparable magnitude. Their spatial distributions
with respect to the embedded illumination sources lead us to suggest that they
may be attributed to different ionization stages of the same family of
carriers.


title: An Apparent Hard X-ray Decline of CH Cygni

abstract:
  CH Cygni is a symbiotic star consisting of an M giant and an accreting white
dwarf, which is known to be a highly variable X-ray source with a complex,
two-component, spectra. Here we report on two Suzaku observations of CH Cyg,
taken in 2006 January and May, during which the system was seen to be in a soft
X-ray bright, hard X-ray faint state. Based on the extraordinary strength of
the 6.4 keV fluorescent Fe K-alpha line, we show that the hard X-rays observed
with Suzaku are dominated by scattering.


title:
SDSS 0809+1729: Connections Between Extremely Metal Poor Galaxies and
  Gamma Ray Burst Hosts

abstract:
  We discuss the serendipitous discovery of an extremely metal poor galaxy,
SDSS 0809+1729, classified as a star in the Sloan Digital Sky Survey (SDSS).
The galaxy has a redshift z = 0.0441 and a B-band absolute magnitude M_B =
-17.1. With a metallicity of log(O/H)+12~7.44 or ~1/20 solar, this galaxy is
among the 10 most metal poor emission-line galaxies known. SDSS 0809+1729 is a
blue compact galaxy (BCG) with a stellar age of ~4.5 Myr, a star formation rate
of 0.18 Msun/yr, and a large gas-phase electron density ~367/cm^3. Similar
values of these parameters are common among other extremely metal poor
galaxies, including IZw18. SDSS 0809+1729 is, however, unusual among BCGs
because it lies in the same region of the luminosity-metallicity diagram as the
two lowest metallicity long duration gamma ray burst (GRB) hosts. For a given
B-band luminosity, both nearby GRB hosts and SDSS 0809+1729 have systematically
lower metallicities than dwarf irregulars, the majority of BCGs, and normal
star-forming galaxies. Because the star formation properties of SDSS 0809+1729
are similar to nearby long duration GRB hosts, SDSS 0809+1729 may be a
potential GRB host. Identification of larger samples of similar extremely metal
poor objects may provide important insights into the conditions required to
produce long duration GRBs.


title:
Testing X-ray Measurements of Galaxy Clusters with Cosmological
  Simulations

abstract:
  X-ray observations of galaxy clusters potentially provide powerful
cosmological probes if systematics due to our incomplete knowledge of the
intracluster medium (ICM) physics are understood and controlled. In this paper,
we present mock Chandra analyses of cosmological cluster simulations and assess
X-ray measurements of galaxy cluster properties using a model and procedure
essentially identical to that used in real data analysis. We show that
reconstruction of three-dimensional ICM density and temperature profiles is
excellent for relaxed clusters, but still reasonably accurate for unrelaxed
systems. The total ICM mass is measured quite accurately (<6%) in all clusters,
while the hydrostatic estimate of the gravitationally bound mass is biased low
by about 5%-20% through the virial region, primarily due to additional pressure
support provided by subsonic bulk motions in the ICM, ubiquitous in our
simulations even in relaxed systems. Gas fraction determinations are therefore
biased high; the bias increases toward cluster outskirts and depends
sensitively on its dynamical state, but we do not observe significant trends of
the bias with cluster mass or redshift. We also find that different average ICM
temperatures, such as the X-ray spectroscopic Tspec and gas-mass-weighted Tmg,
are related to each other by a constant factor with a relatively small
object-to-object scatter and no systematic trend with mass, redshift or the
dynamical state of clusters. We briefly discuss direct applications of our
results for different cluster-based cosmological tests.


title: Formation of Narrow Dust Rings in Circumstellar Debris Disks

abstract:
  Narrow dust rings observed around some young stars (e.g., HR 4796A) need to
be confined. We present a possible explanation for the formation and
confinement of such rings in optically thin circumstellar disks, without
invoking shepherding planets. If an enhancement of dust grains (e.g., due to a
catastrophic collision) occurs somewhere in the disk, photoelectric emission
from the grains can heat the gas to temperatures well above that of the dust.
The gas orbits with super(sub)-Keplerian speeds inward (outward) of the
associated pressure maximum. This tends to concentrate the grains into a narrow
region. The rise in dust density leads to further heating and a stronger
concentration of grains. A narrow dust ring forms as a result of this
instability. We show that this mechanism not only operates around early-type
stars that have high UV fluxes, but also around stars with spectral types as
late as K. This implies that this process is generic and may have occurred
during the lifetime of each circumstellar disk. We examine the stringent
upper-limit on the H2 column density in the HR 4796A disk and find it to be
compatible with the presence of a significant amount of hydrogen gas in the
disk. We also compute the OI and CII infrared line fluxes expected from various
debris disks and show that these will be easily detectable by the upcoming
Herschel mission. Herschel will be instrumental in detecting and characterizing
gas in these disks.


title:
SFI++ I: A New I-band Tully-Fisher Template, the Cluster Peculiar
  Velocity Dispersion and H0

abstract:
  The SFI++ consists of ~5000 spiral galaxies which have measurements suitable
for the application of the I-band Tully-Fisher (TF) relation. This sample
builds on the SCI and SFI samples published in the 1990s but includes
significant amounts of new data as well as improved methods for parameter
determination. We derive a new I-band TF relation from a subset of this sample
which consists of 807 galaxies in the fields of 31 nearby clusters and groups.
This sample constitutes the largest ever available for the calibration of the
TF template and extends the range of line-widths over which the template is
reliably measured. Careful accounting is made of observational and sample
biases such as incompleteness, finite cluster size, galaxy morphology and
environment. We find evidence for a type-dependent TF slope which is shallower
for early type than for late type spirals. The line-of-sight cluster peculiar
velocity dispersion is measured for the sample of 31 clusters. This value is
directly related to the spectrum of initial density fluctuations and thus
provides an independent verification of the best fit WMAP cosmology and an
estimate of Omega^0.6 sigma_8 = 0.52+/-0.06. We also provide an independent
measure of the TF zeropoint using 17 galaxies in the SFI++ sample for which
Cepheid distances are available. In combination with the ``basket of clusters''
template relation these calibrator galaxies provide a measure of H0 = 74+/-2
(random) +/-6 (systematic) km/s/Mpc.


title:
Boltzmann moment equation approach for the numerical study of
  anisotropic stellar disks

abstract:
  We present the Boltzmann moment equation approach for the dynamics of stars
(BEADS-2D), which is a finite-difference Eulerian numerical code designed for
the modelling of anisotropic and non-axisymmetric flat stellar disks. The
BEADS-2D code solves the Boltzmann moment equations up to second order in the
thin-disk approximation. This allows us to obtain the anisotropy of the
velocity ellipsoid and the vertex deviation in the plane of the disk. We study
the time-dependent evolution of exponential stellar disks in the linear regime
and beyond. The disks are initially characterized by different values of the
Toomre parameter Q_s and are embedded in a dark matter halo, yielding a
rotation curve composed of a rigid central part and a flat outer region.
Starting from a near equilibrium state, several unstable modes develop in the
disk. In the early linear phase, the very centre and the large scales are
characterized by growing one-armed and bisymmetric positive density
perturbations, respectively. This is in agreement with expectations from the
swing amplification mechanism of short-wavelength trailing disturbances,
propagating through the disk centre. In the late linear phase, the overall
appearance is dominated by a two-armed spiral structure localized within the
outer Lindblad resonance (OLR). During the non-linear evolutionary phase,
radial mass redistribution due to the gravitational torques of spiral arms
produces an outflow of mass, which forms a ring at the OLR, and an inflow of
mass, which forms a transient central bar. This process of mass redistribution
is self-regulatory and it terminates when spiral arms diminish due to a
shortage of matter. Finally, a compact central disk and a diffuse ring at the
OLR are formed (the abstract is abridged).


title: Kinematics of Globular Cluster Systems

abstract:
  I review the field of globular cluster system (GCS) kinematics, including a
brief primer on observational methods. The kinematical structures of spiral
galaxy GCSs so far appear to be broadly similar. The inferred rotation and mass
profiles of elliptical galaxy halos exhibit a diversity of behaviors, requiring
more systematic observational and theoretical studies.


title: SDSS AGNs with X-ray Emission from ROSAT PSPC Pointed Observations

abstract:
  We present a sample of 1744 type 1 active galactic nuclei (AGNs) from the
Sloan Digital Sky Survey (SDSS DR4) spectroscopic catalog with X-ray
counterparts in the White-Giommi-Angelini Catalog (WGACAT) of ROSAT PSPC
pointed observations. Of 1744 X-ray sources, 1410 (80.9%) are new AGN
identifications. Of 4574 SDSS DR4 AGNs for which we found radio matches in the
catalog of radio sources from the FIRST catalog, 224 turned up in our sample of
SDSS X-ray AGNs. The sample objects are given in a catalog that contains
optical and X-ray parameters along with radio emission parameters where
available. We illustrate the content of our catalog and its potential for AGN
science by providing statistical relationships for the catalog data. The
potential of the morphological information is emphasized by confronting the
statistics of optically resolved and unresolved AGNs. The immediate properties
of the catalog objects include significant correlation of X-ray and optical
fluxes, which is consistent with expectations. Also expected is the decrease of
X-ray flux toward higher redshifts. The X-ray to optical flux ratio for the
unresolved AGNs exhibits a decline toward higher redshifts, in agreement with
previous results. The resolved AGNs, however, display the opposite trend. At a
given optical brightness, X-ray fluxes of radio-quiet AGNs by a factor of 2. We
caution, however, that because of the variety of selection effects present in
both the WGACAT and the SDSS, the interpretation of any relationships based on
our sample of X-ray AGNs requires a careful analysis of these effects.


title: Exotic Earths: Forming Habitable Worlds with Giant Planet Migration

abstract:
  Close-in giant planets (e.g. ``Hot Jupiters'') are thought to form far from
their host stars and migrate inward, through the terrestrial planet zone, via
torques with a massive gaseous disk. Here we simulate terrestrial planet growth
during and after giant planet migration. Several-Earth mass planets also form
interior to the migrating Jovian planet, analogous to recently-discovered ``Hot
Earths''. Very water-rich, Earth-mass planets form from surviving material
outside the giant planet's orbit, often in the Habitable Zone and with low
orbital eccentricities. More than a third of the known systems of giant planets
may harbor Earth-like planets.


title: Temporal and Angular Properties of GRB Jets Emerging from Massive Stars

abstract:
  We study the long-term evolution of relativistic jets in collapsars and
examine the effects of viewing angle on the subsequent gamma ray bursts. We
carry out a series of high-resolution simulations of a jet propagating through
a stellar envelope in 2D cylindrical coordinates using the FLASH relativistic
hydrodynamics module. For the first time, simulations are carried out using an
adaptive mesh that allows for a large dynamic range inside the star while still
being efficient enough to follow the evolution of the jet long after it breaks
out from the star. Our simulations allow us to single out three phases in the
jet evolution: a precursor phase in which relativistic material turbulently
shed from the head of the jet first emerges from the star, a shocked jet phase
where a fully shocked jet of material is emerging, and an unshocked jet phase
where the jet consists of a free-streaming, unshocked core surrounded by a thin
boundary layer of shocked jet material. The appearance of these phases will be
different to observers at different angles. The precursor has a wide opening
angle and would be visible far off axis. The shocked phase has a relatively
narrow opening angle that is constant in time. During the unshocked jet phase
the opening angle increases logarithmically with time. As a consequence, some
observers see prolonged dead times of emission even for constant properties of
the jet injected in the stellar core. We also present an analytic model that is
able to reproduce the overall properties of the jet and its evolution. We
finally discuss the observational implications of our results, emphasizing the
possible ways to test progenitor models through the effects of jet propagation
in the star. In an appendix, we present 1D and 2D tests of the FLASH
relativistic hydrodynamics module.


title: Limits to Transits of the Neptune-mass planet orbiting Gl 581

abstract:
  We have monitored the Neptune-mass exoplanet-hosting M-dwarf Gl 581 with the
1m Swope Telescope at Las Campanas Observatory over two predicted transit
epochs. A neutral density filter centered at 550nm was used during the first
epoch, yielding 6.33 hours of continuous light curve coverage with an average
photometric precision of 1.6 mmags and a cadence of 2.85 min. The second epoch
was monitored in B-band over 5.85 hours, with an average photometric precision
of 1.2 mmags and 4.28 min cadence. No transits are apparent on either night,
indicating that the orbital inclination is less than 88.1 deg for all planets
with radius larger than 0.38 R_Nep = 1.48 R_Earth. Because planets of most
reasonable interior composition have radii larger than 1.55 R_Earth we place an
inclination limit for the system of 88.1 deg. The corresponding minimum mass of
Gl 581b remains 0.97 M_Nep = 16.6 M_Earth.


title:
Nonlinear shear-current dynamo and magnetic helicity transport in
  sheared turbulence

abstract:
  The nonlinear mean-field dynamo due to a shear-current effect in a nonhelical
homogeneous turbulence with a mean velocity shear is discussed. The transport
of magnetic helicity as a dynamical nonlinearity is taken into account. The
shear-current effect is associated with the ${\bf W} {\bf \times} {\bf J}$ term
in the mean electromotive force, where ${\bf W}$ is the mean vorticity due to
the large-scale shear motions and ${\bf J}$ is the mean electric current. This
effect causes the generation of large-scale magnetic field in a turbulence with
large hydrodynamic and magnetic Reynolds numbers. The dynamo action due to the
shear-current effect depends on the spatial scaling of the correlation time
$\tau(k)$ of the background turbulence, where $k$ is the wave number. For
Kolmogorov scaling, $\tau(k) \propto k^{-2/3}$, the dynamo instability occurs,
while when $\tau(k) \propto k^{-2}$ (small hydrodynamic and magnetic Reynolds
numbers) there is no the dynamo action in a sheared nonhelical turbulence. The
magnetic helicity flux strongly affects the magnetic field dynamics in the
nonlinear stage of the dynamo action. Numerical solutions of the nonlinear
mean-field dynamo equations which take into account the shear-current effect,
show that if the magnetic helicity flux is not small, the saturated level of
the mean magnetic field is of the order of the equipartition field determined
by the turbulent kinetic energy. Turbulence with a large-scale velocity shear
is a universal feature in astrophysics, and the obtained results can be
important for elucidation of origin of the large-scale magnetic fields in
astrophysical sheared turbulence.


title: Ultra High Energy Cosmic Radiation: Experimental and Theoretical Status

abstract:
  We give a brief overview of the current experimental and theoretical status
of cosmic rays above ~10**17 eV. We focus on the role of large scale magnetic
fields and on multi-messenger aspects linking charged cosmic ray with secondary
gamma-ray and neutrino fluxes.


title:
Search for Associations Containing Young stars (SACY): I. Sample &
  Searching Method

abstract:
  We report results from a high-resolution optical spectroscopic survey aimed
to search for nearby young associations and young stars among optical
counterparts of ROSAT All-Sky Survey X-ray sources in the Southern Hemisphere.
We selected 1953 late-type (B-V >= 0.6), potentially young, optical
counterparts out of a total of 9574 1RXS sources for follow-up observations. At
least one high-resolution spectrum was obtained for each of 1511 targets. This
paper is the first in a series presenting the results of the SACY survey. Here
we describe our sample and our observations. We describe a convergence method
in the (UVW) velocity space to find associations. As an example, we discuss the
validity of this method in the framework of the BetaPic Association.


title: On the Age of Stars Harboring Transiting Planets

abstract:
  Results of photometric surveys have brought to light the existence of a
population of giant planets orbiting their host stars even closer than the hot
Jupiters (HJ), with orbital periods below 3 days. The reason why radial
velocity surveys were not able to detect these very-hot Jupiters (VHJ) is under
discussion. A possible explanation is that these close-in planets are
short-lived, being evaporated on short time-scales due to UV flux of their host
stars. In this case, stars hosting transiting VHJ planets would be
systematically younger than those in the radial velocity sample. We have used
the UVES spectrograph (VLT-UT2 telescope) to obtain high resolution spectra of
5 faint stars hosting transiting planets, namely, OGLE-TR-10, 56, 111, 113 and
TrES-1. Previously obtained CORALIE spectra of HD189733, and published data on
the other transiting planet-hosts were also used. The immediate objective is to
estimate ages via Li abundances, using the Ca II activity-age relation, and
from the analysis of the stellar rotational velocity. For the stars for which
we have spectra, Li abundances were computed as in Israelian et al. (2004)
using the stellar parameters derived in Santos et al. (2006). The chromospheric
activity index $S_{US}$ was built as the ratio of the flux within the core of
the Ca II H & K lines and the flux in two nearby continuum regions. The index
$S_{US}$ was calibrated to Mount Wilson index $S_{MW}$ allowing the computation
of the Ca II H & K corrected for the photospheric contribution. These values
were then used to derive the ages by means of the Henry et al. (1996)
activity-age relation. Bearing in mind the limitations of the ages derived by
Li abundances, chromospheric activity, and stellar rotational velocities, none
of the stars studied in this paper seem to be younger than 0.5 Gyr.


title:
Preliminary Results from Detector-Based Throughput Calibration of the
  CTIO Mosaic Imager and Blanco Telescope Using a Tunable Laser

abstract:
  We describe the scientific motivation for achieving photometric precision and
accuracy below the 1% level, and we present a calibration philosophy based on
using calibrated detectors rather than celestial sources as the fundamental
metrology reference. A description of the apparatus and methodology is
presented, as well as preliminary measurements of relative system throughput
vs. wavelength for the Mosaic imager at the CTIO Blanco 4m telescope. We
measure the throughput of the optics, filter, and detector by comparing the
flux seen by the instrument to that seen by a precisely calibrated monitor
photodiode, using a tunable laser as the illumination source. This allows us to
measure the transmission properties of the system, passband by passband, with
full pupil illumination of the entire optical train. These preliminary results
are sufficiently promising that we intend to further pursue this technique,
particularly for next-generation survey projects such as PanSTARRS and LSST.


title: Short time scale pulse stability of the Crab pulsar in the optical band

abstract:
  The fine structure and the variations of the optical pulse shape and phase of
the Crab pulsar are studied on various time scales. The observations have been
carried out on 4-m William Hershel and 6-m BTA telescopes with APD photon
counter, photomultiplier based 4-channel photometer and PSD based panoramic
spectrophotopolarimeter with 1$\mu$s time resolution in 1994, 1999, 2003 and
2005-2006 years. The upper limit on the pulsar precession on Dec 2, 1999 is
placed in the 10 s - 2 hours time range. The evidence of a varying from set to
set fine structure of the main pulse is found in the 1999 and 2003 years data.
No such fine structure is detected in the integral pulse shape of 1994, 1999
and 2003 years.
  The drastic change of the pulse shape in the 2005-2006 years set is detected
along with the pulse shape variability and quasi-periodic phase shifts.


title:
Hubble diagram of gamma-ray bursts and prevalence of energy conditions
  in Friedmann-Lema\^itre-Robertson-Walker Cosmology

abstract:
  In this {\sl Letter} we construct the Hubble diagram (HD) for the standard
Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmological model after enforcing
it with the general relativistic energy conditions, heeding to investigate
whether it still stands on as the leading scenario for cosmology in face of the
distance modulus-redshift relation of a sample of GRBs that had their redshifts
properly estimated and corrected upon applying on the data analysis the {\sl
Ghirlanda relation} (Ghirlanda et al. 2004) and the recently discovered {\sl
Firmani et al. relation} (Firmani et al. 2006a). Our $\chi^2$ analysis support
the view that FLRW plus the strong energy condition (SEC) is what better fits
the GRB data. But this is not the whole story, since for a cosmological
constant $\Lambda \neq 0$ the FLRW+SEC analysis with undefined $p=p(\rho)$
suggests that $\Lambda$ is not constant anyhow, because it does not follows the
$p= \omega \rho$ HD, with $\omega=-1$. Thenceforth, one concludes that either
the cosmological constant does not exist at all, and consequently one is left
with the FLRW+SEC which fits properly the GRBs HD and there is no late-time
acceleration, or it does exist but should be time-varying. This all is contrary
to current views based on SNIa observations that advogate for an actual
constant $\Lambda$ and an accelerating universe. In connection to the results
above, this last argumentation would imply that either there is something wrong
with the SNIa interpretation regarding cosmic late-time acceleration
(Middleditch 2006) or we will have to move away from general relativity. We
would better to think that general relativity is still the most correct theory
of gravity.


title: Accelerating Hilbert-Einstein universe without dynamic dark energy

abstract:
  By using an unmodified Einstein gravity theory it is shown that all of the
speeding-up effects taking place in the current universe are entirely due to
the quantum effects associated with the background radiation or to the
combination of such effects with those derived from the presence of a
cosmological constant, without invoking any dynamic dark energy component. We
obtain that in both cases the universe accelerates at a rate slightly beyond
what is predicted by a cosmological constant but does not induce any big rip
singularity in the finite future.


title: Abundance structure of the Galactic disk

abstract:
  The current knowledge of the abundance structure in the Milky Way is
reviewed. Special emphasis is put on recent results for stars with kinematics
typical of the thin and the thick disks, respectively, and how these results
can, apart from studying the Milky Way also give information about the origin
of the elements. Two on-going studies are high-lighted. One that presents new
data for stars with kinematics typical of the Hercules stream and one for a
small number of dwarf stars high above the galactic plane. These indicate that
the thick disk is a homogeneous structure and that the Hercules stream perhaps
is part of the metal-rich thick disk. Furthermore, new abundance determinations
for Mn for stars with kinematics typical of the thin and the thick disk are
presented. From these results the suggestion is that the observed trends for Mn
in the Milky Way disks can be explained by metallicity dependent SN II yields.
The impacts of surveys on the studies of the elemental abundance trends in the
Galaxy are discussed. It is argued that when it comes to furthering our
understanding of the abundance structure in the Galactic disk future and
ongoing surveys' major impact will be in the form of catalogues to select
targets from for high resolution spectroscopic follow-up. For a correct
interpretation of the results from these follow-up studies it is important that
the surveys have well understood completeness characteristics.


title:
Neutron Star Asteroseismology. Axial Crust Oscillations in the Cowling
  Approximation

abstract:
  Recent observations of quasi-periodic oscillations in the aftermath of giant
flares in soft gamma-ray repeaters suggest a close coupling between the seismic
motion of the crust after a major quake and the modes of oscillations in a
magnetar. In this paper we consider the purely elastic modes of oscillation in
the crust of a neutron star in the relativistic Cowling approximation
(disregarding any magnetic field). We determine the axial crust modes for a
large set of stellar models, using a state-of-the-art crust equation of state
and a wide range of core masses and radii. We also devise useful approximate
formulae for the mode-frequencies. We show that the relative crust thickness is
well described by a function of the compactness of the star and a parameter
describing the compressibility of the crust only. Considering the observational
data for SGR 1900+14 and SGR 1806-20, we demonstrate how our results can be
used to constrain the mass and radius of an oscillating neutron star.


title:
Damping of Compressional MHD Waves In Quiescent Prominences and
  Prominence-Corona Transition Region (PCTR)

abstract:
  The effects of radiative losses due to Newtonian cooling and MHD turbulence
have been considered to examine the spatial damping of linear compressional
waves in quiescent prominences and prominence-corona transition region (PCTR).
The radiative losses give acceptable damping lengths for the slow mode wave for
the radiative relaxation time in the range (10-1000s). From prominence
seismology, the values of opacity and turbulent kinematic viscosity have been
inferred. It has been found that for a given value of radiative relaxation
time, the high frequency slow mode waves are highly damped. We have also
investigated the possible role of MHD turbulence in damping of MHD waves and
found a turbulent viscosity can re-produce the observed damping time and
damping length in prominences, especially in PCTR.


title: Hydrodynamic Thermonuclear Runaways in Superbursts

abstract:
  We calculate the thermal and dynamical evolution of the surface layers of an
accreting neutron star during the rise of a superburst. For the first few hours
following unstable 12C ignition, the nuclear energy release is transported by
convection. However, as the base temperature rises, the heating time becomes
shorter than the eddy turnover time and convection becomes inefficient. This
results in a hydrodynamic nuclear runaway, in which the heating time becomes
shorter than the local dynamical time. Such hydrodynamic burning can drive
shock waves into the surrounding layers and may be the trigger for the normal
X-ray burst found to immediately precede the onset of the superburst in both
cases where the Rossi X-Ray Timing Explorer was observing.


title:
The Type Ia supernova 2004S, a clone of SN 2001el, and the optimal
  photometric bands for extinction estimation

abstract:
  We present optical (UBVRI) and near-infrared (YJHK) photometry of the normal
Type Ia supernova 2004S. We also present eight optical spectra and one near-IR
spectrum of SN 2004S. The light curves and spectra are nearly identical to
those of SN 2001el. This is the first time we have seen optical and IR light
curves of two Type Ia supernovae match so closely. Within the one parameter
family of light curves for normal Type Ia supernovae, that two objects should
have such similar light curves implies that they had identical intrinsic colors
and produced similar amounts of Ni-56. From the similarities of the light curve
shapes we obtain a set of extinctions as a function of wavelength which allows
a simultaneous solution for the distance modulus difference of the two objects,
the difference of the host galaxy extinctions, and R_V. Since SN 2001el had
roughly an order of magnitude more host galaxy extinction than SN 2004S, the
value of R_V = 2.15 (+0.24 -0.22) pertains primarily to dust in the host galaxy
of SN 2001el. We have also shown via Monte Carlo simulations that adding rest
frame J-band photometry to the complement of BVRI photometry of Type Ia SNe
decreases the uncertainty in the distance modulus by a factor of 2.7. A
combination of rest frame optical and near-IR photometry clearly gives more
accurate distances than using rest frame optical photometry alone.


title:
Optical and X-Ray Observations of GRB 060526: A Complex Afterglow
  Consistent with An Achromatic Jet Break

abstract:
  We obtained 98 R-band and 18 B, r', i' images of the optical afterglow of GRB
060526 (z=3.21) with the MDM 1.3m, 2.4m, and the PROMPT telescopes in Cerro
Tololo over the 5 nights following the burst trigger. Combining these data with
other optical observations reported in GCN and the Swift-XRT observations, we
compare the optical and X-ray afterglow light curves of GRB 060526. Both the
optical and X-ray afterglow light curves show rich features, such as flares and
breaks. The densely sampled optical observations provide very good coverage at
T>1.e4 sec. We observed a break at 2.4e5 sec in the optical afterglow light
curve. Compared with the X-ray afterglow light curve, the break is consistent
with an achromatic break supporting the beaming models of GRBs. However, the
pre-break and post-break temporal decay slopes are difficult to explain in
simple afterglow models. We estimated a jet angle of \theta_j ~ 7 degrees and a
prompt emission size of R_{prompt} ~ 2e14 cm. In addition, we detected several
optical flares with amplitudes of \Delta m ~ 0.2, 0.6, and 0.2 mag. The X-ray
afterglows detected by Swift have shown complicated decay patterns. Recently,
many well-sampled optical afterglows also show decays with flares and multiple
breaks. GRB 060526 provides an additional case of such a complex, well observed
optical afterglow. The accumulated well-sampled afterglows indicate that most
of the optical afterglows are complex.


title:
The evolution of host mass and black hole mass in QSOs from the 2dF QSO
  Redshift Survey

abstract:
  We investigate the relation between the mass of super-massive black holes
(Mbh) in QSOs and the mass of the dark matter halos hosting them (Mdh). We
measure the widths of broad emission lines (Mgii lambda 2798, Civ lambda 1549)
from QSO composite spectra as a function of redshift. These widths are then
used to determine virial black hole mass estimates.
  We compare our virial black hole mass estimates to dark matter halo masses
for QSO hosts derived by Croom et al. (2005) based on measurements of QSO
clustering. This enables us to trace the Mbh-Mdh relation over the redshift
range z=0.5 to 2.5. We calculate the mean zero-point of the Mbh-Mdh relation to
be Mbh=10^(8.4+/-0.2)Msun for an Mdh=10^(12.5)Msun. These data are then
compared with several models connecting Mbh and Mdh as well as recent
hydrodynamical simulations of galaxy evolution. We note that the flux limited
nature of QSO samples can cause a Malmquist-type bias in the measured
zero-point of the Mbh-Mdh relation. The magnitude of this bias depends on the
scatter in the Mbh-Mdh relation, and we reevaluate the zero-point assuming
three published values for this scatter.
  (abridged)


title: Joining the Hubble Flow: Implications for Expanding Space

abstract:
  The concept of expanding space has come under fire recently as being
inadequate and even misleading in describing the motion of test particles in
the universe. Previous investigations have suffered from a number of
shortcomings, which we seek to correct. We study the motion of test particles
in the universe in detail, solving the geodesic equations of General Relativity
for a number of cosmological models. In particular, we use analytic methods to
examine whether particles removed from the Hubble flow asymptotically rejoin
the Hubble flow, a topic that has caused confusion because of differing
definitions and invalid reasoning. We conclude that particles in eternally
expanding but otherwise arbitrary universes do not in general rejoin the Hubble
flow.


title: What do exotic equations of state have to offer?

abstract:
  We present a short general overview of the main features of exotic models of
neutron stars, focusing on the structural and dynamical predictions derived
from them. In particular, we discuss the presence of ``normal'' quark matter
and Color-Flavor Locked (CFL) states, including their possible self-bound
versions, and mention some different proposals emerging from the study of QCD
microphysics. A connection with actual observed data is the main goal to be
addressed at this talk and along the meeting. It is demonstrated that exotic
equations of state are {\it not} soft if the vacuum contributions are large
enough, and argued that recent measurements of high pulsar masses ($M \geq 2
M_{\odot}$) create problems for {\it hadronic} models in which hyperons should
be present.


title: Spectropolarimetric Survey of Hydrogen-rich White Dwarf Stars

abstract:
  We have conducted a survey of 61 southern white dwarfs searching for magnetic
fields using Zeeman spectropolarimetry. Our objective is to obtain a magnetic
field distribution for these objects and, in particular, to find white dwarfs
with weak fields. We found one possible candidate (WD 0310-688) that may have a
weak magnetic field of -6.1+/-2.2 kG. Next, we determine the fraction and
distribution of magnetic white dwarfs in the Solar neighborhood, and
investigate the probability of finding more of these objects based on the
current incidence of magnetism in white dwarfs within 20 pc of the Sun. We have
also analyzed the spectra of the white dwarfs to obtain effective temperatures
and surface gravities.


title:
Super-critically accreting stellar-mass black holes as ultraluminous
  X-ray sources

abstract:
  We derive the luminosity-temperature relation for the super-critically
accreting black holes (BHs) and compare it to the data on ultraluminous X-ray
sources (ULXs). At super-Eddington accretion rates, an outflow forms within the
spherization radius. We construct the accretion disc model accounting for the
advection and the outflow, and compute characteristic disc temperatures. The
bolometric luminosity exceeds the Eddington luminosity L_Edd by a logarithmic
factor 1+0.6 ln mdot (where mdot is the accretion rate in Eddington units) and
the wind kinetic luminosity is close to L_Edd. The apparent luminosity for the
face-on observer is 2-7 times higher because of geometrical beaming. Such an
observer has a direct view of the inner hot accretion disc, which has a peak
temperature T_max of a few keV in stellar-mass BHs. The emitted spectrum
extends as a power-law F_E ~ E**{-1} down to the temperature at the
spherization radius T_sp ~ mdot**(-1/2) keV. We associate T_max with a few keV
spectral components and T_sp with the soft, 0.1-0.2 keV components observed in
ULXs. An edge-on observer sees only the soft emission from the extended
envelope, with the photosphere radius exceeding the spherization radius by
orders of magnitude. The dependence of the photosphere temperature on
luminosity is consistent with that observed in the super-Eddington accreting
BHs SS 433 and V4641 Sgr. Strong outflows combined with the large intrinsic
X-ray luminosity of the central BH explain naturally the presence of the
photoionized nebulae around ULXs. An excellent agreement between the model and
the observational data strongly argues in favour of ULXs being super-critically
accreting, stellar-mass BHs similar to SS 433, but viewed close to the symmetry
axis.


title:
The Magnificent Seven in the dusty prairie -- The role of interstellar
  absorption on the observed neutron star population

abstract:
  The Magnificent Seven have all been discovered by their exceptional soft
X-ray spectra and high ratios of X-ray to optical flux. They all are considered
to be nearby sources. Searching for similar neutron stars with larger
distances, one expects larger interstellar absorption resulting in harder X-ray
counterparts. Current interstellar absorption treatment depends on chosen
abundances and scattering cross-sections of the elements as well as on the 3D
distribution of the interstellar medium. After a discussion of these factors we
use the comprehensive 3D measurements of the Local Bubble by Lallement et al.
2003 to construct two simple models of the 3D distribution of the hydrogen
column density. We test these models by using a set of soft X-ray sources with
known distances. Finally, we discuss possible applications for distance
estimations and population synthesis studies.


title:
Observational evidence for a changing tilt of the accretion disk with
  respect to the orbital plane in Her X-1 over its 35 day cycle

abstract:
  Analysis and interpretation of the Her X-1 X-ray light curve obtained with
the ASM onbord RXTE over the period 1996 February to 2004 September is
presented. We report that the features found previously in the averaged X-ray
lightcurve are confirmed by the new RXTE/ASM data. In particular, anomalous
dips and post-eclipse recoveries in two successive orbits in the short-on state
are found to be prominent and stable details of the light curve. We argue that
a change of the tilt of the accretion disk over the 35-day period is necessary
to account for these features and show that our numerical model can explain
such a behavior of the disk and reproduce the observed details of the light
curve.


title: Faint open clusters with 2MASS: BH 63, Lyng\aa 2, Lyng\aa 12 and King 20

abstract:
  Structural and dynamical parameters of faint open clusters are probed with
quality 2MASS-photometry and analytical procedures developed for bright
clusters. We derive fundamental parameters of the faint open clusters Lynga2,
BH63, Lyng12 and King20, the last three of which have no prior determinations.
We also focus on the structure and dynamical state of these clusters. 2MASS
photometry with errors smaller than 0.2mag are used to build CMDs, RDPs, CMDs,
luminosity and mass functions. Colour-magnitude filters are used to isolate
probable member stars. Field-star decontamination is applied to Lynga2, Lynga12
and King20. Reddening values are in the range 0.22-1.9, with BH63 the most
reddened object. Ages of Lynga2, King20, Lynga12 and BH63 are ~90, ~200, ~560
and 700Myr, respectively. The RDPs of Lynga12 and King20 are well-represented
by King profiles. Total stellar masses (extrapolating the MFs to stars with
0.08Mo) range from ~340Mo (BH63) to ~2300Mo (Lynga12). Observed masses are
\~1/4$ of these values. In all clusters the core mass function is flatter than
the halo's. Faint open clusters can be probed with 2MASS when associated with
colour-magnitude filters and field-star decontamination. BH63 appears to be in
an advanced dynamical state, both in the core and halo. To a lesser degree the
same applies to King20. Marginal evidence of dynamical evolution is present in
the cores of Lynga2 and Lynga12.


title:
Interplanetary Lyman $\alpha$ line profiles: variations with solar
  activity cycle

abstract:
  Interplanetary Lyman alpha line profiles are derived from the SWAN H cell
data measurements. The measurements cover a 6-year period from solar minimum
(1996) to after the solar maximum of 2001. This allows us to study the
variations of the line profiles with solar activity. These line profiles were
used to derive line shifts and line widths in the interplanetary medium for
various angles of the LOS with the interstellar flow direction. The SWAN data
results were then compared to an interplanetary background upwind spectrum
obtained by STIS/HST in March 2001. We find that the LOS upwind velocity
associated with the mean line shift of the IP \lya line varies from 25.7 km/s
to 21.4 km/s from solar minimum to solar maximum. Most of this change is linked
with variations in the radiation pressure. LOS kinetic temperatures derived
from IP line widths do not vary monotonically with the upwind angle of the LOS.
This is not compatible with calculations of IP line profiles based on hot model
distributions of interplanetary hydrogen. We also find that the line profiles
get narrower during solar maximum. The results obtained on the line widths (LOS
temperature) show that the IP line is composed of two components scattered by
two hydrogen populations with different bulk velocities and temperature. This
is a clear signature of the heliospheric interface on the line profiles seen at
1 AU from the sun.


title: New observations of the halo radial temperature structure in NGC7662

abstract:
  We report on our studies of the physical structure of the planetary nebula
(PN) NGC7662. Using (3D) Integral Field Spectroscopy we have been able to
measure the electron temperature more accurately and at a larger number of
radial locations than before. Here we briefly present our method by which we
find a strong positive temperature gradient with increasing radius. According
to hydrodynamic models a hot halo, when compared to the central star, can be
the product of the passage of an ionization front (e.g. Marten 1993). Such a
gradient is not found in equilibrium models, and this finding - when confirmed
for other objects - strongly advocates the use of hydrodynamic models when
modeling PN halos.


title:
Link between the chromospheric network and magnetic structures of the
  corona

abstract:
  Recent work suggested that the traditional picture of the corona above the
quiet Sun being rooted in the magnetic concentrations of the chromospheric
network alone is strongly questionable. Building on that previous study we
explore the impact of magnetic configurations in the photosphere and the low
corona on the magnetic connectivity from the network to the corona.
Observational studies of this connectivity are often utilizing magnetic field
extrapolations. However, it is open to which extent such extrapolations really
represent the connectivity found on the Sun, as observations are not able to
resolve all fine scale magnetic structures. The present numerical experiments
aim at contributing to this question. We investigated random
salt-and-pepper-type distributions of kilo-Gauss internetwork flux elements
carrying some $10^{15}$ to $10^{17}$ Mx, which are hardly distinguishable by
current observational techniques. These photospheric distributions are then
extrapolated into the corona using different sets of boundary conditions at the
bottom and the top. This allows us to investigate the fraction of network flux
which is connected to the corona, as well as the locations of those coronal
regions which are connected to the network patches. We find that with current
instrumentation one cannot really determine from observations, which regions on
the quiet Sun surface, i.e. in the network and internetwork, are connected to
which parts of the corona through extrapolation techniques. Future
spectro-polarimetric instruments, such as with Solar B or GREGOR, will provide
a higher sensitivity, and studies like the present one could help to estimate
to which extent one can then pinpoint the connection from the chromosphere to
the corona.


title: X-ray Spectroscopy of Cool Stars

abstract:
  High-resolution X-ray spectroscopy has addressed not only various topics in
coronal physics of stars, but has also uncovered important features relevant
for our understanding of stellar evolution and the stellar environment. I
summarize recent progress in coronal X-ray spectroscopy and in particular also
discuss new results from studies of X-rays from pre-main sequence stars.


title: The spectral resolving power of irregularly sampled time series

abstract:
  A method is presented for investigating the periodic signal content of time
series in which a number of signals is present, such as arising from the
observation of multiperiodic oscillating stars in observational
asteroseismology. Standard Fourier analysis tends only to be effective in cases
when the data are perfectly regularly sampled. During normal telescope
operation it is often the case that there are large, diurnal, gaps in the data,
that data are missing, or that the data are not regularly sampled at all. For
this reason it is advantageous to perform the analysis as much as possible in
the time domain. Furthermore, for quantitative analyses of the frequency
content and power of all real signals, it is of importance to have good
estimates of the errors on these parameters. This is easiest to perform if one
can use linear combinations of the measurements. Here such a linear method is
described. The method is based in part on well-known techniques in radio
technology used in every FM radio receiver, and in part on the SOLA inverse
method


title:
A search for substellar members in the Praesepe and sigma Orionis
  clusters

abstract:
  (Abridged). We have conducted deep photometric searches for substellar
members of the Praesepe (0.5-1 Gyr) and sigma Orionis (3 Myr) star clusters
using the Sloan i' and z' filters, the 3.5-m and the 5-m Hale telescopes on the
Calar Alto and Palomar Observatories, respectively. The total area surveyed was
1177 arcmin^2 (Praesepe) and 1122 arcmin^2 (sigma Orionis) down to 5-sigma
detection limits of i'= 24.5 and z'= 24 mag, corresponding to masses of 50-55
M_Jup (Praesepe) and 6 M_Jup (sigma Orionis). Besides recovering previously
known cluster members reported in the literature, we have identified new
photometric candidates in both clusters whose masses expand the full range
covered by our study. In sigma Orionis, follow-up NIR photometry has allowed us
to confirm the likely cluster membership of three newly discovered
planetary-mass objects. The substellar mass function of sigma Orionis, which is
complete from the star-brown dwarf borderline down to 7 M_Jup, keeps rising
smoothly with a slope of alpha = 0.6^{+0.5}_{-0.1}. Very interestingly, one of
the faintest Praesepe candidates for which we have also obtained follow-up JHK
photometry nicely fits the expected optical and infrared photometric sequence
of the cluster. From its colors, we have estimated its spectral type in the
L4-L6 range. If confirmed as a true Praesepe member, it would become the first
L-type brown dwarf (50-60 M_Jup) identified in an intermediate-age star
cluster. Our derivation of the Praesepe mass function depends strongly on the
cluster age. For the youngest possible ages (500-700 Myr), our results suggest
that there is a deficit of Praesepe brown dwarfs in the central regions of the
cluster, while the similarity between the Praesepe and sigma Orionis mass
functions increases qualitatively for models older than 800 Myr.


title: The Lack of Halo Ultraluminous X-ray Sources

abstract:
  The premise that Ultraluminous X-ray sources (ULXs) exist beyond the optical
extent of nearby galaxies is investigated. A published catalog containing 41
ULX candidates located between 1 and ~3 times the standard D_{25} isophotal
radius of their putative host galaxies is examined. Twenty-one of these sources
have spectroscopically-confirmed distances. All 21 are background objects
giving a 95% probability that at least 37 of the 41 candidates are background
sources. Thirty-nine of the 41 sources have X-ray-to-optical flux ratios,
-1.6<log(F_{X}/F_{O})<+1.3, consistent with those of background active galactic
nuclei. (The remaining two are not detected in optical to a weak limit of
m_{B}~21.5$ mag corresponding to log(F_{X}/F_{O})\gtrsim 1.6.) The uniform
spatial distribution of the sample is also consistent with a background
population. This evidence suggests that ULXs rarely, if at all, exist beyond
the distribution of luminous matter in nearby galaxies and, as a consequence,
there is no correlation between the population of ULXs and halo objects such as
old globular clusters or Pop~III remnants.


title: High Resolution Imaging of Molecular Outflows in Massive Young Stars

abstract:
  We present high angular resolution observations toward two massive star
forming regions IRAS 18264-1152 and IRAS 23151+5912 with the Plateau de Bure
Interferometer (PdBI) in the SiO (J=2-1) and H$^{13}$CO$^{+}$ (J=1-0) lines and
at 1.3 mm and 3.4 mm continuum, and with the Very Large Array (VLA) in the
NH$_3$ (J,K)=(1,1), (2,2) lines. The NH$_3$ (1,1) and (2,2) emission is
detected toward IRAS 18264-1152 only. For IRAS 18264-1152, the SiO observations
reveal at least two quasi-perpendicular outflows with high collimation factors,
and the most dominant feature is a redshifted jet-like outflow with very high
velocities up to about ${\Delta}v=60$ kms$^{-1}$ with respect to the systemic
velocity. The very-high-velocity component (${\Delta}v=22 - 60$ kms$^{-1}$) of
this outflow is spatially offset from its high-velocity (${\Delta}v=3 - 21$
kms$^{-1}$) component. The SiO line profiles and position-velocity
characteristics of these two components suggest that this outflow can be driven
by an underlying precessing jet. For IRAS 23151+5912, the bipolar but mainly
blueshifted SiO outflow coincides with the inner parts of the single-dish CO
outflow. In particular the quasi-parabolic shape of the blueshifted outflow
coincides with the near-infrared nebulosity and is consistent with entrainment
of the gas by an underlying wide-angle wind. The analysis of the molecular
outflow data of the two luminous sources further support high-mass stars
forming via a disk-mediated accretion process similar to low-mass stars.


title: The v_c-sigma_c relation in low mass and low surface brightness galaxies

abstract:
  We present an updated investigation of the relation between large scale disk
circular velocity, v_c, and bulge velocity dispersion, sigma_c. New bulge
velocity dispersions are measured for a sample of 11 low surface brightness
(LSB) and 7 high surface brightness (HSB) spiral galaxies for which v_c is
known from published optical or HI rotation curves. We find that, while LSB
galaxies appear to define the upper envelope of the region occupied by HSB
galaxies (having relatively larger v_c for any given sigma_c), the distinction
between LSB and HSB galaxies in the v_c-sigma_c plane becomes less pronounced
for sigma_c <= 80 km/s. We conclude that either the scatter of the v_c-sigma_c
relation is a function of v_c (and hence galaxy mass) or that the character of
the v_c-sigma_c relation changes at v_c ~ 80 km/s. Some inplications of our
findings are discussed.


title:
The evolution of the near-IR galaxy Luminosity Function and colour
  bimodality up to z ~ 2 from the UKIDSS Ultra Deep Survey Early Data Release

abstract:
  We present new results on the cosmological evolution of the near-infrared
galaxy luminosity function, derived from the analysis of a new sample of
\~22,000 K(AB) < 22.5 galaxies selected over an area of 0.6 square degrees from
the Early Data Release of the UKIDSS Ultra Deep Survey (UDS). Our study has
exploited the multi-wavelength coverage of the UDS field provided by the new
UKIDSS WFCAM K and J-band imaging, the Subaru/XMM-Newton Deep Survey and the
Spitzer-SWIRE Survey. The unique combination of large area and depth provided
by this new survey minimises the complicating effect of cosmic variance and has
allowed us, for the first time, to trace the evolution of the brightest sources
out to z~2 with good statistical accuracy.
  In agreement with previous studies we find that the characteristic luminosity
of the near-infrared luminosity function brightens by 1 magnitude between z=0
and z~2, while the total density decreases by a factor ~2. Using the rest-frame
(U-B) colour to split the sample into red and blue galaxies, we confirm the
classic luminosity-dependent colour bimodality at z<1. However, the strength of
the colour bimodality is found to be a decreasing function of redshift, and
seems to disappear by z>1.5. Due to the large size of our sample we are able to
investigate the differing cosmological evolution of the red and blue galaxy
populations. It is found that the space density of the brightest red galaxies
(M_K < -23) stays approximately constant with redshift, and that these sources
dominate the bright-end of the luminosity function at redshifts z<1. In
contrast, the brightening of the characteristic luminosity and mild decrease in
space density displayed by the blue galaxy population leads them to dominate
the bright-end of the luminosity function at redshifts z>1.


title: B-Mode contamination by synchrotron emission from 3-years WMAP data

abstract:
  We study the contamination of the B-mode of the Cosmic Microwave Background
Polarization (CMBP) by Galactic synchrotron in the lowest emission regions of
the sky. The 22.8-GHz polarization map of the 3-years WMAP data release is used
to identify and analyse such regions. Two areas are selected with
signal-to-noise ratio S/N<2 and S/N<3, covering ~16% and ~26% fraction of the
sky, respectively. The polarization power spectra of these two areas are
dominated by the sky signal on large angular scales (multipoles l < 15), while
the noise prevails on degree scales. Angular extrapolations show that the
synchrotron emission competes with the CMBP B-mode signal for tensor-to-scalar
perturbation power ratio $T/S = 10^{-3}$ -- $10^{-2}$ at 70-GHz in the 16%
lowest emission sky (S/N<2 area). These values worsen by a factor ~5 in the
S/N<3 region. The novelty is that our estimates regard the whole lowest
emission regions and outline a contamination better than that of the whole high
Galactic latitude sky found by the WMAP team (T/S>0.3). Such regions allow $T/S
\sim 10^{-3}$ to be measured directly which approximately corresponds to the
limit imposed by using a sky coverage of 15%. This opens interesting
perspectives to investigate the inflationary model space in lowest emission
regions.


title: Spectropolarimetry of the Classical T Tauri Star TW Hydrae

abstract:
  We present high resolution (R ~ 60,000) circular spectropolarimetry of the
classical T Tauri star TW Hydrae. We analyze 12 photospheric absorption lines
and measure the net longitudinal magnetic field for 6 consecutive nights. While
no net polarization is detected the first five nights, a significant
photospheric field of Bz = 149 \pm 33 G is found on the sixth night. To rule
out spurious instrumental polarization, we apply the same analysis technique to
several non-magnetic telluric lines, detecting no significant polarization. We
further demonstrate the reality of this field detection by showing that the
splitting between right and left polarized components in these 12 photospheric
lines shows a linear trend with Lande g-factor times wavelength squared, as
predicted by the Zeeman effect. However, this longitudinal field detection is
still much lower than that which would result if a pure dipole magnetic
geometry is responsible for the mean magnetic field strength of 2.6 kG
previously reported for TW Hya. We also detect strong circular polarization in
the He I 5876 and the Ca II 8498 emission lines, indicating a strong field in
the line formation region of these features. The polarization of the Ca II line
is substantially weaker than that of the He I line, which we interpret as due
to a larger contribution to the Ca II line from chromospheric emission in which
the polarization signals cancel. However, the presence of polarization in the
Ca II line indicates that accretion shocks on Classical T Tauri stars do
produce narrow emission features in the infrared triplet lines of Calcium.


title:
OGLE 2004-BLG-254: a K3 III Galactic Bulge Giant spatially resolved by a
  single microlens

abstract:
  We present an analysis of OGLE 2004-BLG-254, a high-magnification and
relatively short duration microlensing event in which the source star, a Bulge
K3-giant, has been spatially resolved by a point-like lens. We have obtained
dense photometric coverage of the event light curve with OGLE and PLANET
telescopes, as well as a high signal-to-noise ratio spectrum taken while the
source was still magnified by 20, using the UVES/VLT spectrograph. Our dense
coverage of this event allows us to measure limb darkening of the source star
in the I and R bands. We also compare previous measurements of linear
limb-darkening coefficients involving GK-giant stars with predictions from
ATLAS atmosphere models. We discuss the case of K-giants and find a
disagreement between limb-darkening measurements and model predictions, which
may be caused by the inadequacy of the linear limb-darkening law.


title: Accretion in rho-Ophiuchi brown dwarfs: infrared hydrogen line ratios

abstract:
  Mass accretion rate determinations are fundamental for an understanding of
the evolution of pre-main sequence star circumstellar disks. Magnetospheric
accretion models are used to derive values of the mass accretion rates in
objects of very different properties, from brown dwarfs to intermediate-mass
stars; we test the validity of these models in the brown dwarf regime, where
the stellar mass and luminosity, as well as the mass accretion rate, are much
lower than in T Tauri stars. We have measured simultaneously two infrared
hydrogen lines, Pab and Brg, in a sample of 16 objects in the star-forming
region rho-Oph. The sample inc ludes 7 very low mass objects and brown dwarfs
and 9 T Tauri stars. Brown dwarfs where both lines are detected have a ratio
Pab/Brg of ~2. Larger values, >=3.5, are only found among the T Tauri stars.
The low line ratios in brown dwarfs indicate that the lines cannot originate in
the column of gas accreting from the disk onto the star along the magnetic
field lines, and we suggest that they form instead in the shocked photosphere,
heated to temperatures of ~3500 K. If so, in analogy to veiling estimates in T
Tauri stars, the hydrogen infrared line fluxes may provide a reliable measure
of the accretion rate in brown dwarfs.


title:
Non-gray rotating stellar models and the evolutionary history of the
  Orion Nebular Cluster

abstract:
  Rotational evolution in the pre-main sequence (PMS) is described with new
sets of PMS evolutionary tracks including rotation, non-gray boundary
conditions (BCs) and either low (LCE) or high convection efficiency (HCE).
Using observational data and our theoretical predictions, we aim at
constraining 1) the differences obtained for the rotational evolution of stars
within the ONC by means of these different sets of models; 2) the initial
angular momentum of low mass stars, by means of their templates in the ONC. We
discuss the reliability of current stellar models for the PMS. While the 2D
radiation hydrodynamic simulations predict HCE in PMS, semi-empirical
calibrations either seem to require that convection is less efficient in PMS
than in the following MS phase or are still contradictory. We derive stellar
masses and ages for the ONC by using both LCE and HCE. The resulting mass
distribution for the bulk of the ONC population is in the range 0.2$-$0.3
{\msun} for our non-gray models and in the range 0.1$-$0.3{\msun} for models
having gray BCs. In agreement with Herbst et al. (2002) we find that a large
percentage ($\sim$70%) of low-mass stars (M\simlt 0.5{\msun} for LCE;
M\simlt0.35{\msun} for HCE) in the ONC appears to be fast rotators (P$<$4days).
Three possibilities are open: 1) $\sim$70% of the ONC low mass stars lose their
disk at early evolutionary phases; 2)their locking period is shorter; 3) the
period evolution is linked to a different morphology of the magnetic fields of
the two groups of stars. We also estimate the range of initial angular momentum
consistent with the observed periods. The comparisons made indicate that a
second parameter is needed to describe convection in the PMS, possibly related
to the structural effect of a dynamo magnetic field.


title:
A simple analysis of halo density profiles using gravitational lensing
  time delays

abstract:
  Gravitational lensing time delays depend upon the Hubble constant and the
density distribution of the lensing galaxies. This allows one to either model
the lens and estimate the Hubble constant, or to use a prior on the Hubble
constant from other studies and investigate what the preferred density
distribution is. Some studies have required compact dark matter halos (constant
M/L ratio) in order to reconcile gravitational lenses with the HST/WMAP value
of the Hubble constant (72 +/- 8 km/s /Mpc and 72 +/- 5 km/s /Mpc,
respectively). This is in direct contradiction with X-ray, stellar dynamical,
and weak lensing studies, which all point towards extended halos and isothermal
density profiles. In this work, we examine an up-to-date sample of 13 lensing
galaxies resulting in a data set consisting of 21 time delays. We select
systems in which there is a single primary lensing galaxy (e.g. excluding
systems undergoing mergers). Analysis is performed using analytic models based
upon a powerlaw density profile (rho \propto r^-n) of which the isothermal
profile is a special case (n = 2). This yields a value of n = 2.11+/-0.12
(3sigma) for the mean profile when modeling with a prior on the Hubble
constant, which is only consistent with isothermality within 3 sigma. Note that
this is a formal error from our calculations, and does not include the impact
of sample selection or simplifications in the lens modeling. We conclude that
time delays are a useful probe of density profiles, in particular as a function
of the environment in which the lens resides, when combined with a prior on the
Hubble constant.


title: On the ultra-high energy cosmic ray horizon

abstract:
  We compute the ultra-high energy cosmic ray horizon, i.e. the distance up to
which cosmic ray sources may significantly contribute to the fluxes above a
certain threshold on the observed energies. We obtain results both for proton
and heavy nuclei sources.


title:
The Chrysalis Opens? Photometry from the Eta Carinae HST Treasury
  Project, 2002-2006

abstract:
  During the past decade Eta Car has brightened markedly, possibly indicating a
change of state. Here we summarize photometry gathered by the Hubble Space
Telescope as part of the HST Treasury Project on this object. Our data include
STIS/CCD acquisition images, ACS/HRC images in four filters, and synthetic
photometry in flux-calibrated STIS spectra. The HST's spatial resolution allows
us to examine the central star separate from the bright circumstellar ejecta.
Its apparent brightness continued to increase briskly during 2002--06,
especially after the mid-2003 spectroscopic event. If this trend continues, the
central star will soon become brighter than its ejecta, quite different from
the state that existed only a few years ago. One precedent may be the rapid
change observed in 1938--1953. We conjecture that the star's mass-loss rate has
been decreasing throughout the past century.


title:
A Spectroscopic Survey of Redshift 1.4<z<3.0 Galaxies in the Goods-North
  Field: Survey Description, Catalogs, and Properties

abstract:
  We present the results of a spectroscopic survey with the Keck I telescope of
more than 280 star-forming galaxies and AGN at redshifts 1.4<z<3.0 in the
GOODS-N field. Candidates are selected by their UGR colors using the ``BM/BX''
criteria to target redshift 1.4<z<2.5 galaxies and the LBG criteria to target
redshift z~3 galaxies; combined these samples account for ~25-30% of the R and
K-band counts to R=25.5 and K(AB)=24.4, respectively. The sample of 212 BM/BX
galaxies and 74 LBGs is presently the largest spectroscopic sample of galaxies
at z>1.4 in GOODS-N. Extensive multi-wavelength data allow us to investigate
the stellar populations, stellar masses, bolometric luminosities (L_bol), and
extinction of z~2 galaxies. Deep Chandra and Spitzer data indicate that the
sample includes galaxies with a wide range in L_bol, from 10^10 L_sun to >10^12
L_sun, and covering 4 orders of magnitude in dust obscuration (L_bol/L_UV). The
sample includes galaxies with a large dynamic range in evolutionary state, from
very young galaxies (ages <50 Myr) with small stellar masses (M* ~ 10^9 M_sun)
to evolved galaxies (ages >2 Gyr) with stellar masses comparable to the most
massive galaxies at these redshifts (M* > 10^11 M_sun). Spitzer data indicate
that the optical sample includes some fraction of the obscured AGN population
at high redshifts: at least 3 of 11 AGN in the z>1.4 sample are undetected in
the deep X-ray data but exhibit power-law SEDs longward of ~2 micron
(rest-frame) indicative of obscured AGN. The results of our survey indicate
that rest-frame UV selection and spectroscopy presently constitute the most
time-wise efficient method of culling large samples of high redshift galaxies
with a wide range in intrinsic properties, and the data presented here will add
significantly to the multi-wavelength legacy of the GOODS survey. [Abridged]


title:
On the inconsistency between the black hole mass function inferred from
  M_bh-sigma and M_bh-L correlation

abstract:
  Black hole masses are tightly correlated with the stellar velocity
dispersions of the bulges which surround them, and slightly less-well
correlated with the bulge luminosity. It is common to use these correlations to
estimate the expected abundance of massive black holes. This is usually done by
starting from an observed distribution of velocity dispersions or luminosities
and then changing variables. This procedure neglects the fact that there is
intrinsic scatter in these black hole mass--observable correlations. Accounting
for this scatter results in estimates of black hole abundances which are larger
by almost an order of magnitude at masses >10^9 M_sun. Including this scatter
is particularly important for models which seek to infer quasar lifetimes and
duty cycles from the local black hole mass function. However, even when scatter
has been accounted for, the M_bh-sigma relation predicts fewer massive black
holes than does the M_bh-L relation. This is because the sigma-L relation in
the black hole samples currently available is inconsistent with that in the
SDSS sample from which the distributions of L or sigma are based: the black
hole samples have smaller L for a given sigma, or larger sigma for a given L.
The sigma-L relation in the black hole samples is similarly discrepant with
that in other samples of nearby early-type galaxies. This suggests that current
black hole samples are biased: if this is a selection rather than physical
effect, then the M_bh-sigma and M_bh-L relations currently in the literature
are also biased from their true values.


title: Observational Constraints on Trojans of Transiting Extrasolar Planets

abstract:
  Theoretical studies predict that Trojans are likely a frequent byproduct of
planet formation and evolution. We present a novel method of detecting Trojan
companions to transiting extrasolar planets which involves comparing the time
of central eclipse with the time of the stellar reflex velocity null. We
demonstrate that this method offers the potential to detect terrestrial-mass
Trojans using existing ground-based observatories. This method rules out Trojan
companions to HD 209458b and HD 149026b more massive than ~13 Earth masses and
\~25 Earth masses at a 99.9% confidence level. Such a Trojan would be
dynamically stable, would not yet have been detected by photometric or
spectroscopic monitoring, and would be unrecognizable from radial velocity
observations alone. We outline the future prospects for this method, and show
that the detection of a "Hot Trojan" of any mass would place a significant
constraint on theories of orbital migration.


title: The Spitzer-IRS spectrum of SMP LMC 11

abstract:
  We present the first mid-infrared spectra of SMP LMC 11 in the Large
Magellanic Cloud. While this object resembles a planetary nebula in the
optical, its infrared properties are more similar to an object in transition
from the asymptotic giant branch to the planetary nebula phase. A warm dust
continuum dominates the infrared spectrum. The peak emission corresponds to a
mean dust temperature of 330 K. The spectrum shows overlapping molecular
absorption bands from 12 to 17 um corresponding to acetylene and polyacetylenic
chains and benzene. This is the first detection of C4H2, C6H2, C6H6 and other
molecules in an extragalactic object. The infrared spectrum of SMP LMC 11 is
similar in many ways to that of the pre-planetary nebula AFGL 618. The IRS
spectrum shows little evidence of nitrogen-based molecules which are commonly
seen in Galactic AGB stars. Polycyclic aromatic hydrocarbons are also absent
from the spectrum. The detection of the [NeII] 12.8 um line in the infrared and
other forbidden emission lines in the optical indicates that an ionized region
is present.


title:
Selection bias in the M_BH-sigma and M_BH-L correlations and its
  consequences

abstract:
  It is common to estimate black hole abundances by using a measured
correlation between black hole mass and another more easily measured observable
such as the velocity dispersion or luminosity of the surrounding bulge. The
correlation is used to transform the distribution of the observable into an
estimate of the distribution of black hole masses. However, different
observables provide different estimates: the Mbh-sigma relation predicts fewer
massive black holes than does the Mbh-L relation. This is because the sigma-L
relation in black hole samples currently available is inconsistent with that in
the SDSS sample, from which the distributions of L or sigma are based: the
black hole samples have smaller L for a given sigma or have larger sigma for a
given L. This is true whether L is estimated in the optical or in the NIR. If
this is a selection rather than physical effect, then the Mbh-sigma and Mbh-L
relations currently in the literature are also biased from their true values.
We provide a framework for describing the effect of this bias. We then combine
it with a model of the bias to make an estimate of the true intrinsic
relations. While we do not claim to have understood the source of the bias, our
simple model is able to reproduce the observed trends. If we have correctly
modeled the selection effect, then our analysis suggests that the bias in the
<Mbh|sigma> relation is likely to be small, whereas the <Mbh|L> relation is
biased towards predicting more massive black holes for a given luminosity. In
addition, it is likely that the Mbh-L relation is entirely a consequence of
more fundamental relations between Mbh and sigma, and between sigma and L. The
intrinsic relation we find suggests that at fixed luminosity, older galaxies
tend to host more massive black holes.


title: The sigma - L correlation in Nearby Early-Type Galaxies

abstract:
  Early-type galaxy velocity dispersions and luminosities are correlated. The
correlation estimated in local samples (< 100 Mpc) differs from that measured
more recently in the SDSS. This is true even when systematics in the SDSS
photometric and spectroscopic parameters have been accounted-for. We show that
this is also true for the ENEAR sample if galaxy luminosities are estimated
using distances which have been corrected for peculiar motions. We then show
that, because the estimate of the `true' distance is derived from a correlation
with velocity dispersion, in this case the D_n-sigma relation, using it in the
sigma-L relation leads to an artificially tight relation with a biased slope.
Making no correction for peculiar velocities results in a sigma-L relation
which is very similar to that of the SDSS, although with larger scatter. We
also measure the sigma-L correlation in a mock ENEAR catalog, in which the
underlying galaxy sample has the same sigma-L correlation as seen in the SDSS.
The mock catalog produces the same D_n-sigma relation as the data, the same
biased slope when D_n-sigma distances are used to estimate luminosities, and
good agreement with the input sigma-L relation when redshift is used as the
distance indicator. This provides further evidence that the true sigma-L
relation of ENEAR galaxies is indeed very similar to that of SDSS early-types.
Our results suggest that local sigma-L relations which are based on Fundamental
Plane distances should also be re-evaluated. Our findings also have important
implications for black hole demographics; the best direct estimates of the
masses of supermassive black holes come from local galaxies, so estimates of
the black hole mass function are more safely made by working with the Mbh-sigma
correlation than with Mbh-L.