title:
The baseline intracluster entropy profile from gravitational structure
  formation

abstract:
  The radial entropy profile of the hot gas in clusters of galaxies tends to
follow a power law in radius outside of the cluster core. Here we present a
simple formula giving both the normalization and slope for the power-law
entropy profiles of clusters that form in the absence of non-gravitational
processes such as radiative cooling and subsequent feedback. It is based on
seventy-one clusters drawn from four separate cosmological simulations, two
using smoothed-particle hydrodynamics (SPH) and two using adaptive-mesh
refinement (AMR), and can be used as a baseline for assessing the impact of
non-gravitational processes on the intracluster medium outside of cluster
cores. All the simulations produce clusters with self-similar structure in
which the normalization of the entropy profile scales linearly with cluster
temperature, and these profiles are in excellent agreement outside of 0.2
r_200. Because the observed entropy profiles of clusters do not scale linearly
with temperature, our models confirm that non-gravitational processes are
necessary to break the self-similarity seen in the simulations. However, the
core entropy levels found by the two codes used here significantly differ, with
the AMR code producing nearly twice as much entropy at the centre of a cluster.


title: Gas distribution, kinematics and star formation in faint dwarf galaxies

abstract:
  We compare the gas distribution, kinematics and the current star formation in
a sample of 10 very faint (-13.37 < M_B < -9.55) dwarf galaxies. For 5 of these
galaxies we present fresh, high sensitivity, GMRT HI 21cm observations. For all
our galaxies we construct maps of the HI column density at a constant linear
resolution of ~300 pc; this forms an excellent data set to check for the
presence of a threshold column density for star formation. We find that while
current star formation (as traced by Halpha emission) is confined to regions
with relatively large (N_HI > (0.4 -1.7) X 10^{21} atoms cm^{-2}) HI column
density, the morphology of the Halpha emission is in general not correlated
with that of the high HI column density gas. Thus, while high column density
gas may be necessary for star formation, in this sample at least, it is not
sufficient to ensure that star formation does in fact occur. We examine the
line profiles of the HI emission, but do not find a simple relation between
regions with complex line profiles and those with on-going star formation.
Finally, we examine the very fine scale (~20-100 pc) distribution of the HI
gas, and find that at these scales the emission exhibits a variety of shell
like, clumpy and filamentary features. The Halpha emission is sometimes
associated with high density HI clumps, sometimes the Halpha emission lies
inside a high density shell, and sometimes there is no correspondence between
the Halpha emission and the HI clumps. In summary, the interplay between star
formation and gas density in these galaxy does not seem to show the simple
large scale patterns observed in brighter galaxies (abridged).


title:
The Local Rate and the Progenitor Lifetimes of Short-Hard Gamma-Ray
  Bursts: Synthesis and Predictions for LIGO

abstract:
  The recent discovery of the first four afterglows of short-hard gamma-ray
bursts (SHBs), suggests that they typically result from long-lived progenitor
systems. The most popular progenitor model invokes the merger of either double
neutron star (DNS) binaries or neutron star-black hole (NS-BH) systems. Such
events are strong sources of gravitational-waves (GWs) and might be detected by
ground-based GW observatories. In this work we combine the census of SHB
observations with refined theoretical analysis to perform a critical evaluation
of the compact binary model. We then explore the implications for GW detection
of these events. Beginning from the measured star-formation rate through cosmic
time, we consider what intrinsic luminosity and lifetime distributions can
reproduce the known SHB redshifts and luminosities as well as the peak flux
distribution of the large BATSE SHB sample. We find that: (1) The typical
progenitor lifetime is long. Assuming lognormal lifetime distribution the
typical lifetime is >4[1] Gyr (2[3]\sigma c.l.). If the lifetime distribution
is a power-law with index \eta then \eta>-0.5 [-1] (2[3] \sigma c.l.). This
result is difficult to reconcile with the properties of the observed galactic
DNS population, suggesting that if SHBs do result from DNS mergers then the
observed galactic binaries do not represent the cosmic one. (2) We find that
the local rate of SHBs is larger than 10Gpc^-3/yr and may be higher by several
orders of magnitude, significantly above previous estimates. (3) Assuming that
SHBs do result from compact binaries, our predictions for the LIGO and VIRGO
event rates are encouraging: The chance for detection by current facilities is
not negligible, while a coincident detection of GW and electromagnetic
radiation from an SHB is guaranteed for next-generation observatories.


title:
Oxygen Gas Abundances at z~1.4: Implications for the Chemical Evolution
  History of Galaxies

abstract:
  The 1<z<2 redshift window hosts the peak of the star formation and metal
production rates. Studies of the metal content of the star forming galaxies at
these epochs are however sparse. We report VLT-ISAAC near-infrared spectroscopy
for a sample of five [OII]-selected, M_B,AB<-21.5, z~1.4 galaxies, by which we
measured Hbeta and [OIII]5007 emission line fluxes from J-band spectra, and
Halpha line fluxes plus upper limits for [NII]6584 fluxes from H-band spectra.
The z~1.4 galaxies are characterized by the high [OIII]/[OII] line ratios, low
extinction and low metallicity that are typical of lower luminosity CADIS
galaxies at 0.4<z<0.7, and of more luminous Lyman Break Galaxies at z~3, but
not seen in CFRS galaxies at 0.4<z<0.9. This type of spectrum (e.g., high
[OIII]/[OII]) is seen in progressively more luminous galaxies as the redshift
increases. These spectra are caused by a combination of high ionisation
parameter q and lower [O/H]. Pegase2 chemical evolution models are used to
relate the observed metallicities and luminosities of z~1.4 galaxies to galaxy
samples at lower and higher redshift. Not surpringsingly, we see a relationship
between redshift and inferred chemical age. We suppose that the metal-enriched
reservoirs of star forming gas that we are probing at intermediate redshifts
are being mostly consumed to build up both the disk and the bulge components of
spiral galaxies. Finally, our analysis of the metallicity-luminosity relation
at 0<z<1.5 suggests that the period of rapid chemical evolution may take place
progressively in lower mass systems as the universe ages. These results are
consistent with a ``downsizing'' type picture in the sense that particular
signatures (e.g., high [OIII]/[OII] or low [O/H]) are seen in progressively
more luminous (massive) systems at higher redshifts.


title: The Initial Mass Function as given by the fragmentation

abstract:
  The dichotomy between a universal mass function (IMF) and a variable IMF
which depends on local physical parameters characterises observational and
theoretical stellar astronomy. In this contribution the available distributions
of probability are briefly reviewed. The physical nature of two of them, gamma
variate and lognormal, is then explained once the framework of the
fragmentation is introduced. Interpolating techniques are then applied to the
sample of the first 10 pc and to the open cluster NGC6649: in both cases
lognormal distribution produces the best fit. The three power law function has
also been investigated and visual comparison with an artificially generated
sample of 100000 stars suggests that the variations in the spectral index are
simply due to the small number of stars available in the observational sample.
In order to derive the sample of masses, a new formula that allows us to
express the mass as a function of the absolute magnitude and (B-V) for MAIN V,
GIANTS III and SUPERGIANTS I is derived.


title: Solar differential rotation and properties of magnetic clouds

abstract:
  The most geoeffective solar drivers are magnetic clouds - a subclass of
coronal mass ejections (CME's) distinguished by the smooth rotation of the
magnetic field inside the structure. The portion of CME's that are magnetic
clouds is maximum at sunspot minimum and mimimum at sunspot maximum. This
portion is determined by the amount of helicity carried away by CME's which in
turn depends on the amount of helicity transferred from the solar interior to
the surface, and on the surface differential rotation. The latter can increase
or reduce, or even reverse the twist of emerging magnetic flux tubes, thus
increasing or reducing the helicity in the corona, or leading to the violation
of the hemispheric helicity rule, respectively. We investigate the CME's
associated with the major geomagnetic storms in the last solar cycle whose
solar sources have been identified, and find that in 10 out of 12 cases of
violation of the hemispheric helicity rule or of highly geoeffective CME's with
no magnetic field rotation, they originate from regions with "anti-solar" type
of surface differential rotation.


title: Binary and Millisecond Pulsars

abstract:
  We review the main properties, demographics and applications of binary and
millisecond radio pulsars. Our knowledge of these exciting objects has greatly
increased in recent years, mainly due to successful surveys which have brought
the known pulsar population to over 1700. There are now 80 binary and
millisecond pulsars associated with the disk of our Galaxy, and a further 103
pulsars in 24 of the Galactic globular clusters. Recent highlights have been
the discovery of the first ever double pulsar system and a recent flurry of
discoveries in globular clusters, in particular Terzan 5.


title:
Can brane dark energy model be probed observationally by distant
  supernovae?

abstract:
  The recent astronomical measurements of distant supernovae as well as other
observations indicate that our universe is presently accelerating. There are
different proposals for the explanation of this acceleration, such as the
cosmological constant $\Lambda$, decaying vacuum energy, an evolving scalar
field (quintessence), phantom energy, etc. Most of these proposals require the
existence of exotic matter with negative pressure violating the strong energy
condition. On the other hand, there have appeared many models which offer
dramatically different mechanisms for the current acceleration, in which dark
energy emerges from the gravity sector rather than from the matter sector. In
this paper, we compare the concordance $\Lambda$CDM model with the
Sahni-Shtanov brane-world models of dark energy by using the Akaike and
Bayesian information criteria. We show that new parameters in the brane model
are not statistically significant in terms of the information criteria,
although the best fit method gives an improved fit to the SNIa data, because of
the additional parameters. This is because the information criteria of model
selection compensate for this advantage by penalizing models having more free
parameters. We conclude that only new future observational data are accurate
enough to give an advantage to dark-energy models of the brane origin, i.e., a
very high-significance detection is required to justify the presence of new
parameters. In our statistical analysis both Riess et al.'s and Astier et al.'s
SNIa samples are used. For stringent constraining parameters of the models the
baryon oscillation peak (BOP) test is used.


title: Weak redshift discretisation in the Local Group of Galaxies?

abstract:
  We discuss the distribution of radial velocities of galaxies belonging to the
Local Group. Two independent samples of galaxies as well as several methods of
reduction from the heliocentric to the galactocentric radial velocities are
explored. We applied the power spectrum analysis using the Hann function as a
weighting method, together with the jackknife error estimation. We performed a
detailed analysis of this approach. The distribution of galaxy redshifts seems
to be non-random. An excess of galaxies with radial velocities of $\sim 24 {km}
\cdot {s}^{-1}$ and $\sim 36 {km} \cdot {s}^{-1}$ is detected, but the effect
is statistically weak. Only one peak for radial velocities of $\sim 24 {km}
\cdot {s}^{-1}$ seems to be confirmed at the confidence level of 95%.


title: The circumstellar disc around the Herbig AeBe star HD169142

abstract:
  We present 7 mm and 3.5 cm wavelength continuum observations toward the
Herbig AeBe star HD169142 performed with the Very Large Array (VLA) with an
angular resolution of ~1". We find that this object exhibits strong (~4.4 mJy),
unresolved (~1") 7 mm continuum emission, being one of the brightest isolated
Herbig AeBe stars ever detected with the VLA at this wavelength. No emission is
detected at 3.5 cm continuum, with a 3 sigma upper limit of ~0.08 mJy. From
these values, we obtain a spectral index of ~2.5 in the 3.5 cm to 7 mm
wavelength range, indicating that the observed flux density at 7mm is most
likely dominated by thermal dust emission coming from a circumstellar disc. We
use available photometric data from the literature to model the spectral energy
distribution (SED) of this object from radio to near-ultraviolet frequencies.
The observed SED can be understood in terms of an irradiated accretion disc
with low mass accretion rate, 10^{-8} solar masses per year, surrounding a star
with an age of ~10 Myr. We infer that the mass of the disc is ~0.04 solar
masses, and is populated by dust grains that have grown to a maximum size of 1
mm everywhere, consistent with the lack of silicate emission at 10 microns.
These features, as well as indications of settling in the wall at the dust
destruction radius, led us to speculate the disc of HD169142 is in an advanced
stage of dust evolution, particularly in its inner regions.


title: Investigating pseudoscalar and scalar dark matter

abstract:
  In this paper another class of Dark Matter candidate particles: the
pseudoscalar and scalar light bosonic candidates, is discussed. Particular care
is devoted to the study of the processes for their detection (which only
involves electrons and photons/X-rays) in a suitable underground experimental
set-up. For this purpose the needed calculations are developed and various
related aspects and phenomenologies are discussed. In particular, it is shown
that - in addition to the WIMP cases already discussed elsewhere - there is
also possibility for a bosonic candidate to account for the 6.3 sigma C.L.
model independent evidence for the presence of a particle DM component in the
galactic halo observed by DAMA/NaI. Allowed regions in these scenarios are
presented also paying particular care on the cosmological interest of the
bosonic candidate.


title: Central energy equipartition in multi-mass models of globular clusters

abstract:
  In the construction of multi-mass King-Michie models of globular clusters, an
approximated central energy equipartition between stars of different masses is
usually imposed by scaling the velocity parameter of each mass class inversely
with the stellar mass, as if the distribution function were isothermal. In this
paper, this 'isothermal approximation' (IA) has been checked and its
consequences on the model parameters studied by a comparison with models
including central energy equipartition correctly. It is found that, under the
IA, the 'temperatures' of a pair of components can differ to a non-negligible
amount for low concentration distributions. It is also found that, in general,
this approximation leads to a significantly reduced mass segregation in
comparison with that given under the exact energy equipartition at the centre.
As a representative example, an isotropic 3-component model fitting a given
projected surface brightness and line-of-sight velocity dispersion profiles is
discussed. In this example, the IA gives a cluster envelope much more
concentrated (central dimensionless potential W=3.3) than under the true
equipartition (W=0.059), as well as a higher logarithmic mass function slope.
As a consequence, the inferred total mass (and then the global mass-to-light
ratio) results a factor 1.4 times lower than the correct value and the amount
of mass in heavy dark remnants is 3.3 times smaller. Under energy
equipartition, the fate of stars having a mass below a certain limit is to
escape from the system. This limit is derived as a function of the mass and W
of the giants and turn-off stars component.


title: Astrometric Light-Travel Time signature of sources in nonlinear motion

abstract:
  Context:Very precise planned space astrometric missions and recent
improvements on imaging capabilities require a detailed review of the
assumptions of classical astrometric modeling.
  Aims:We show that Light-Travel Time must be taken into account to model the
kinematics of astronomical objects in nonlinear motion, even at stellar
distances.
  Methods:A closed expression to include Light-Travel Time in the actual
astrometric models with nonlinear motion is provided. Using a perturbative
approach the expression of the Light-Travel Time signature is derived. We
propose a practical form of the astrometric modelling to be applied in
astrometric data reduction of sources at stellar distances($d>1 pc$).
  Results :We show that the Light-Travel Time signature is relevant at $\muas$
accuracy (or even at $mas$) depending on the time span of the astrometric
measurements. We explain how information about the radial motion of a source
can be obtained. Some estimative numbers are provided for known nearby binary
systems
  Conclusions :In the light of the obtained results, it is clear that this
effect must be taken into account to interpret any kind of precise astrometric
measurements. The effect is particularly interesting in measurements performed
by the planned astrometric space missions (GAIA, SIM, JASMINE, TPF/DARWIN).
Finally an objective criterion is provided to quickly evaluate whether the
Light-Travel Time modeling is required for a given source or system.


title:
Influence of gravity waves on the internal rotation and Li abundance of
  solar-type stars

abstract:
  The Sun's rotation profile and lithium content have been difficult to
understand in the context of conventional models of stellar evolution.
Classical hydrodynamical models predict that the solar interior must rotate
highly differentially, in disagreement with observations. It has recently been
shown that internal waves produced by convection in solar-type stars produce an
asymmetric, shear layer oscillation, similar to Earth's quasi-biennial
oscillation, that leads to efficient angular momentum redistribution from the
core to the envelope. We presents results of a model that successfully
reproduces both the rotation profile and the surface abundance of lithium in
solar-type stars of various ages.


title: Extended sources in the XMM-Newton slew survey

abstract:
  The low background, good spatial resolution and great sensitivity of the
EPIC-pn camera on XMM-Newton give useful limits for the detection of extended
sources even during the short exposures made during slewing maneouvers. In this
paper we attempt to illustrate the potential of the XMM-Newton slew survey as a
tool for analysing flux-limited samples of clusters of galaxies and other
sources of spatially extended X-ray emission.


title: Spacetime foam and high-energy photons

abstract:
  It is shown that high-energy astrophysics can provide information on the
small-scale structure of spacetime.


title:
Present and Future Millimeter VLBI Imaging of Jets in AGN: The Case of
  NRAO 150

abstract:
  The Global mm-VLBI Array is at present the most sensitive 3 mm-VLBI
interferometer and provides images of up to 40 micro-arcsecond resolution.
Using this array, we have monitored the rotation of the innermost jet in the
quasar NRAO 150, which shows an angular speed of ~ 7 deg./yr. Future 3 mm
arrays could include additional stations like ALMA, GBT, LMT, CARMA, SRT,
Yebes, Nobeyama and Noto, which would allow to push VLBI at this wavelength to
sensitivity and image quality levels comparable to those of present VLBI at
centimeter wavelengths. This would improve our knowledge of the accretion
systems and the magneto-hydrodynamics of the innermost jets in AGN and
microquasars.


title:
Single massive stars at the critical rotational velocity: possible links
  with Be and B[e] stars

abstract:
  Using single star models including the effects of shellular rotation with and
without magnetic fields, we show that massive stars at solar metallicity with
initial masses lower than about 20-25 M$_\odot$ and with an initial rotation
above $\sim 350$ km s$^{-1}$ likely reach the critical velocity during their
Main-Sequence phase. This results from the efficient outwards transport of
angular momentum by the meridional circulation. This could be a scenario for
explaining the Be stars. After the Main-Sequence phase, single star in this
mass range can again reach the critical limit when they are on a blue loop
after a red supergiant phase \citep{HL98}. This might be a scenario for the
formation of B[e] stars, however as discussed by Langer & Heger (1998), this
scenario would predict a short B[e] phase (only some 10$^4$ years) with
correspondingly small amounts of mass lost.


title: Observation of V0332+53 over the 2004/2005 outburst with Integral

abstract:
  We present the spectral and temporal analysis of the 2004/2005 outburst of
the transient X-ray pulsar V0332+53 as observed with Integral. After the
discovery of the third cyclotron line in phase averaged spectra (Kreykenbohm et
al 2005, Pottschmidt et al 2005), detailed pulse phase spectroscopy revealed
remarkably little variability of the cyclotron lines through the 4.4s X-ray
pulse (Pottschmidt et al 2005). During the decline of the outburst, the flux
was observed to decay exponentially until 2005 Feb 10 and linearly thereafter.
The spectrum was found to become harder with time, while the folding energy
remained constant. The energy of the fundamental cyclotron line increased with
time from 26.5kev in the RXTE observation up to 29.5kev in the last Integral
one indicating that the emission region is moving closer to the surface of the
neutron star. For a detailed analysis, see Mowlavi et al (2005).


title: The Astrophysical Virtual Observatory to EURO-VO Transition

abstract:
  The Astrophysical Virtual Observatory (AVO) initiative, jointly funded by the
European Commission and six European organisations, had the task of creating
the foundations of a regional scale infrastructure by conducting a research and
demonstration programme on the VO scientific requirements and necessary
technologies. The AVO project is now formally concluded. I highlight AVO's main
achievements and then describe its successor, the EURO-VO project. With its
three new interlinked structures, the Data Centre Alliance, the Facility
Centre, and the Technology Centre, the EURO-VO is the logical next step for the
deployment of an operational VO in Europe.


title:
Properties of X-Ray Rich Gamma Ray Bursts and X-Ray Flashes detected
  with BeppoSAX and Hete-2

abstract:
  We study the spectrum of the prompt emission and the X-ray and optical
afterglow fluxes of 54 X-Ray Rich Gamma Ray Burst (XRRs) and X-Ray Flashes
(XRFs), observed by BeppoSax and HETE-2. A comparison is then performed with
classical Gamma Ray Bursts (GRBs). The goal of this paper is to investigate the
nature of XRRs/XRFs, as high redshift GRBs or off-axis GRBs, analyzing both
their prompt and afterglow properties. We find that the XRR/XRF spectral
indexes of the Band function are similar to those of classical GRBs, whereas
the peak energy is lower by a factor of 4. We study the optical and X-Ray
afterglow properties of the XRRs/XRFs; in particular we analyze the XRR 011030
afterglow. We find that the X-ray and optical flux distributions and the
lightcurves of the XRRs/XRFs sample are consistent with those of classical
GRBs; in particular, they show evidence of a break and no rising temporal
slope. We compare these results with the afterglow predictions of the high
redshift scenario, where XRFs are GRBs at higher redshift and of the off-axis
scenario, where the observed differences are due to viewing angle effects. In
this last framework, we consider jets with a homogeneous, a -2 power-law shaped
and a Gaussian luminosity angular distribution.
  We find that the high redshift scenario can explain some events but not the
total sample of XRRs/XRFs. The off-axis model may be consistent with our
findings when a homogeneous jet is considered. However, given the uncertainties
on the selection effects in our sample, a Gaussian jet viewed at small angles
from the Gaussian core and a power-law shaped cannot be ruled out.


title: X-ray populations in galaxies

abstract:
  Today's sensistive, high resolution Chandra X-ray observations allow the
study of many populations of X-ray sources. The traditional astronomical tools
of photometric diagrams and luminosity functions are now applied to these
populations, and provide the means for classifying the X-ray sources and
probing their evolution. While overall stellar mass drives the amount of X-ray
binaries in old stellar population, the amount of sources in star-forming
galaxies is related to the star formation rate. Shart-lived, luminous, high
mass binaries (HNXBs) dominate these young populations.


title: Epilogue

abstract:
  The IAU Symposium 230, Populations of High Energy Sources in Galaxies, has
been a wide-spectrum affair, with talks discussing results from the soft X-ray
to the Gamma-ray range on virtually the entire universe, from our Galaxy to the
high redshift regions when first galaxies emerged. I do not name any presenter
in this summary, but concentrate on themes and results that I have found
striking.


title: Collective Neutrino Flavor Transformation In Supernovae

abstract:
  We examine coherent active-active channel neutrino flavor evolution in
environments where neutrino-neutrino forward scattering can engender
large-scale collective flavor transformation. We point out a key quantity, the
"total effective energy", which is conserved in several important regimes.
Using this concept, we analyze collective neutrino and antineutrino flavor
oscillation in the "synchronized" mode and what we term the "bi-polar" mode. We
thereby are able to explain why large collective flavor mixing can develop on
short timescales even when vacuum mixing angles are small in, e.g., a dense gas
of initially pure $\nu_e$ and $\bar\nu_e$ with an inverted neutrino mass
hierarchy (an example of bi-polar oscillation). In the context of the spin
precession analogy, we find that the co-rotating frame provides insights into
more general systems, where either the synchronized or bi-polar modes could
arise. For example, we use the co-rotating frame to demonstrate how large
flavor mixing in the bi-polar mode can occur in the presence of a large and
dominant matter background. We use the adiabatic condition to derive a simple
criterion for determining whether the synchronized or bi-polar mode will occur.
Based on this criterion we predict that neutrinos and antineutrinos emitted
from a proto-neutron star in a core-collapse supernova event can experience
synchronized and bi-polar flavor transformations in sequence before
conventional Mikhyev-Smirnov-Wolfenstein (MSW) flavor evolution takes over.
This certainly will affect the analyses of future supernova neutrino signals,
and might affect the treatment of shock re-heating rates and nucleosynthesis
depending on the depth at which collective transformation arises.


title: Investigating Galaxy Evolution with Chandra

abstract:
  Chandra observations show the importance of the X-ray band for studying the
evolution of galaxies. Binary X-ray sources are an easily detectable tracer of
the stellar population. Chandra studies of these populations are giving us
insights into the nature and formation of these binaries, and provide the basis
for diagnostics of galaxy evolution. With Chandra and XMM-Newton we can explore
relatively poorly known aspects of the black hole population of the universe:
ultra-luminous X-ray sources, that may be connected with the 'missing'
intermediate mass black holes predicted by hierarchical galaxy and black hole
formation scenarios; and quiescent supermassive nuclear black holes and their
surroundings, as a way to understand the full range of the AGN phenomenon.
Finally, the X-ray band provides the only way to explore hot plasmas in
galaxies; recent observations are revealing the importance of these plasmas as
vehicles of both chemical enrichment and energy.


title: Gamma Ray Astronomy with Magnetized Zevatrons

abstract:
  Nearby sources of cosmic rays up to a ZeV(=10^21 eV) could be observed with a
multi-messenger approach including secondary gamma-rays and neutrinos. If
cosmic rays above ~10^18 eV are produced in magnetized environments such as
galaxy clusters, the flux of secondary gamma-rays below ~1 TeV can be enhanced
up to several orders of magnitudes compared to unmagnetized sources. A
particular source of enhancement are synchrotron and cascade photons from
e^+e^- pairs produced by protons from sources with relatively steep injection
spectra proportional to E^-2.6. Such sources should be visible at the same time
in ultra-high energy cosmic ray experiments and gamma-ray telescopes.


title: Proper motion Pleiades candidate L-type brown dwarfs

abstract:
  We present results of an optical and near-infrared (IR) 1.8 deg^2 survey in
the Pleiades open cluster to search for substellar objects. From optical I-band
images from the CFHT and J-band images from the 3.5 m CAHA Telescope, we
identify 18 faint and very red L brown dwarf candidates, with I> 20.9 and I-J>
3.2. The follow-up observations of nine objects in the H- and Ks-bands confirm
that eight belong to the IR sequence of the cluster and the proper motion
measurements of seven candidates confirm that they are Pleiades members. A
preliminary estimation of the substellar mass spectrum dN/dM in the form of a
power law M^-alpha provides alpha=0.57+-0.14. We extrapolate this function to
estimate the number of very low-mass brown dwarfs and planetary mass objects
that could be present in the cluster down to 1 M_Jup. Sensitive searches
combining far red and near infrared observations may unveal these objects in a
near future.


title: Size and Properties of the NLR in the Seyfert-2 Galaxy NGC 1386

abstract:
  We study the narrow-line region (NLR) of the Seyfert-2 galaxy NGC 1386 by
means of long-slit spectroscopy obtained with FORS1 at the VLT. We use the
galaxy itself for subtracting the stellar template, applying reddening
corrections to fit the stellar template to the spectra of the NLR. The
continuum gets steadily redder towards the nucleus. The spatial distribution of
the reddening derived from the Balmer decrement differs from the continuum
reddening, indicating dust within the NLR with a varying column density along
the line of sight. Using spatially resolved spectral diagnostics, we find a
transition between central line ratios falling into the AGN regime and outer
ones in the HII-region regime, occuring at a radius of ~6 arcsec (310 pc) in
all three diagnostic diagrams. Applying CLOUDY photoionisation models, we show
that the observed distinction between HII-like and AGN-like ratios in NGC 1386
represents a true difference in ionisation source and cannot be explained by
variations of physical parameters such as ionisation parameter, electron
density or metallicity. We interpret it as a real border between the NLR, i.e.
the central AGN-photoionised region and surrounding HII regions. We derive
surface brightness, electron density, and ionisation parameter as a function of
distance from the nucleus. Both the electron density and the ionisation
parameter decrease with radius. We discuss the consequences of these
observations for the interpretation of the empirical NLR size-luminosity
relation. In the outer part of the NLR, we find evidence for shocks, resulting
in a secondary peak of the electron-density and ionisation-parameter
distribution north of the nucleus. We compare the NLR velocity curve with the
stellar one and discuss the differences.


title: [OIII] profile substructure in radio-quiet quasars

abstract:
  Interactions between the radio jet and the optical emission of the
narrow-line region (NLR) are a well known phenomenon in Seyfert galaxies. Here,
we present the study of possible jet-NLR interactions in five radio-quiet PG
quasars with double or triple radio structure. High spatial and spectral
resolution observations were carried out in the Hbeta-[OIII]5007 wavelength
range. In all cases, there is evidence for [OIII] profile substructure
(shoulders, subpeaks, blueshifted ''broad'' components) with different clarity.
To measure the velocity, line width, intensity, and location of these [OIII]
components, several Gaussians were fitted. Often, the substructures are more
pronounced close to the radio lobes, suggestive of jet-NLR interactions. Our
observations support the unification scheme in which radio-quiet quasars are
assumed to be the luminous cousins of Seyfert galaxies.


title: Optical Spectroscopy of a Flare on Barnard's Star

abstract:
  We present optical spectra of a flare on Barnard's star. Several photospheric
as well as chromospheric species were enhanced by the flare heating. An
analysis of the Balmer lines shows that their shapes are best explained by
Stark broadening rather than chromospheric mass motions. We estimate the
temperature of the flaring region in the lower atmosphere to be >8000 K and the
electron density to be ~10^14 cm^{-3}, similar to values observed in other dM
flares. Because Barnard's star is considered to be one of our oldest neighbors,
a flare of this magnitude is probably quite rare.


title:
Sub-Arcsecond Mid-Infrared Observations of NGC 6240: Limitations of
  AGN-Starburst Power Diagnostics

abstract:
  In order to examine the relative importance of powerful starbursts and
Compton-thick AGNs in NGC 6240, we have obtained mid-infrared images and
low-resolution spectra of the galaxy with sub-arcsecond spatial resolution
using the Keck Telescopes. Despite the high spatial resolution (~200 pc) of our
data, no signature of the hidden AGNs has been detected in the mid-infrared.
The southern nucleus, which we show provides 80-90% of the total 8-25 um
luminosity of the system, has a mid-infrared spectrum and a mid-/far-infrared
spectral energy distribution consistent with starbursts. At the same time,
however, it is also possible to attribute up to 60% of the bolometric
luminosity to an AGN, consistent with X-ray observations, if the AGN is heavily
obscured and emits mostly in the far-infrared. This ambiguity arises because
the intrinsic variation of properties among a given galaxy population (e.g.,
starbursts) introduces at least a factor of a few uncertainty even into the
most robust AGN-starburst diagnostics. We conclude that with present
observations it is not possible to determine the dominant power source in
galaxies when AGN and starburst luminosities are within a factor of a few of
each other.


title:
Morphological analysis of the cm-wave continuum in the dark cloud
  LDN1622

abstract:
  The spectral energy distribution of the dark cloud LDN1622, as measured by
Finkbeiner using WMAP data, drops above 30GHz and is suggestive of a Boltzmann
cutoff in grain rotation frequencies, characteristic of spinning dust emission.
  LDN1622 is conspicuous in the 31 GHz image we obtained with the Cosmic
Background Imager, which is the first cm-wave resolved image of a dark cloud.
The 31GHz emission follows the emission traced by the four IRAS bands. The
normalised cross-correlation of the 31 GHz image with the IRAS images is higher
by 6.6sigma for the 12um and 25um bands than for the 60um and 100um bands:
C(12+25) = 0.76+/-0.02 and C(60+100) = 0.64+/-0.01.
  The mid-IR -- cm-wave correlation in LDN 1622 is evidence for very small
grain (VSG) or continuum emission at 26-36GHz from a hot molecular phase. In
dark clouds and their photon-dominated regions (PDRs) the 12um and 25um
emission is attributed to stochastic heating of the VSGs. The mid-IR and
cm-wave dust emissions arise in a limb-brightened shell coincident with the PDR
of LDN1622, where the incident UV radiation from the Ori OB1b association heats
and charges the grains, as required for spinning dust.


title: OVI in Elliptical Galaxies: Indicators of Cooling Flows

abstract:
  Early-type galaxies often contain a hot X-ray emitting interstellar medium
(3-8E6 K) with an apparent radiative cooling time much less than a Hubble time.
If unopposed by a heating mechanism, the gas will radiatively cool to
temperatures <= 10E4 K at a rate proportional to L_X/T_X, typically 0.03-1
M_solar yr^-1. We can test if gas is cooling through the 3E5 K range by
observing the OVI doublet, whose luminosity is proportional to the cooling
rate. Here we report on a study of an unbiased sample of 24 galaxies, obtaining
Far Ultraviolet Spectroscopic Explorer spectra to complement the X-ray data of
ROSAT} and Chandra. The OVI line emission was detected in about 40% of the
galaxies and at a luminosity level similar to the prediction from the cooling
flow model. There is a correlation between Mdot_OVI and Mdot_X, although there
is significant dispersion about the relationship, where the OVI is brighter or
dimmer than expected by a factor of three or more. If the cooling flow picture
is to be retained, this dispersion requires that cooling flows be
time-dependent, as might occur by the activity of an AGN. However, of detected
objects, those with the highest or lowest values of Mdot_OVI/Mdot_X are not
systematically hot or cool, as one might predict from AGN heating.


title: On the spin-up/spin-down transitions in accreting X-ray binaries

abstract:
  Accreting X-Ray Binaries display a wide range of behaviours. Some of them are
observed to spin up steadily, others to alternate between spin-up and spin-down
states, sometimes superimposed on a longer trend of either spin up or spin
down. Here we interpret this rich phenomenology within a new model of the
disk-magnetosphere interaction. Our model, based on the simplest version of a
purely material torque, accounts for the fact that, when a neutron star is in
the propeller regime, a fraction of the ejected material does not receive
enough energy to completely unbind, and hence falls back into the disk. We show
that the presence of this feedback mass component causes the occurrence of
multiple states available to the system, for a given, constant value of the
mass accretion rate dot{M}_* from the companion star. If the angle chi of the
magnetic dipole axis with respect to the perpendicular to the disk is larger
than a critical value chi_crit, the system eventually settles in a cycle of
spin-up/spin-down transitions for a constant value of dot{M}_* and independent
of the initial conditions. No external perturbations are required to induce the
torque reversals. The transition from spin up to spin down is often accompanied
by a large drop in luminosity. The frequency range spanned in each cycle and
the timescale for torque reversals depend on dot{M}_*, the magnetic field of
the star, the magnetic colatitude chi, and the degree of elasticity regulating
the magnetosphere-disk interaction. The critical angle chi_crit ranges from
\~25-30 deg for a completely elastic interaction to ~40-45 deg for a totally
anelastic one. For chi ~< chi_crit, cycles are no longer possible and the
long-term evolution of the system is a pure spin up. We specifically illustrate
our model in the cases of the X-ray binaries GX 1+4 and 4U 1626-67.


title: Cosmic infrared background and early stellar populations

abstract:
  Cosmic infrared background (CIB) contains information about galaxy
luminosities over the entire history of the Universe and can be a powerful
diagnostic of the early populations otherwise inaccessible to telescopic
studies. Its measurements are very difficult because of the strong IR
foregrounds from the Solar system and the Galaxy. Nevertheless, substantial
recent progress in measuring the CIB and its structure has been made. The
measurements now allow to set significant constraints on early galaxy evolution
and, perhaps, even detect the elusive Population III era. We discuss briefly
the theory behind the CIB, review the latest measurements of the CIB and its
structure, and discuss their implications for detecting and/or constraining the
first stars and their epochs.


title:
Physical component analysis of galaxy cluster weak gravitational lensing
  data

abstract:
  We present a novel approach for reconstructing the projected mass
distribution of clusters of galaxies from sparse and noisy weak gravitational
lensing shear data. The reconstructions are regularised using knowledge gained
from numerical simulations of clusters: trial mass distributions are
constructed from N physically-motivated components, each of which has the
universal density profile and characteristic geometry observed in simulated
clusters. The parameters of these components are assumed to be distributed
\emph{a priori} in the same way as they are in the simulated clusters. Sampling
mass distributions from the components' parameters' posterior probability
density function allows estimates of the mass distribution to be generated,
with error bars. The appropriate number of components is inferred from the data
itself via the Bayesian evidence, and is typically found to be small,
reflecting the quality of the simulated data used in this work. Ensemble
average mass maps are found to be robust to the details of the noise
realisation, and succeed in recovering the input mass distribution (from a
realistic simulated cluster) over a wide range of scales. We comment on the
residuals of the reconstruction and their implications, and discuss the
extension of the method to include strong lensing information.


title:
RXTE Discovery of Multiple Cyclotron Lines during the 2004 December
  Outburst of V0332+53

abstract:
  We present an analysis of the 2-150 keV spectrum of the transient X-ray
pulsar V0332+53 taken with the Rossi X-Ray Timing Explorer (RXTE) in 2004
December. We report on the detection of three cyclotron resonance features at
27, 51, and 74 keV in the phase-averaged data, corresponding to a polar
magnetic field of 2.7 x 10^12 G. After 4U0115+63, this makes V0332+53 the
second accreting neutron star in which more than two cyclotron lines have been
detected; this has now also been confirmed by INTEGRAL. Pulse-phase
spectroscopy reveals remarkably little variability of the cyclotron line
through the 4.4 s X-ray pulse.


title: Spitzer Observations of Massive Red Galaxies at High Redshift

abstract:
  We investigate the properties of massive galaxies at z=1-3.5 using HST
observations, ground-based near-IR imaging, and Spitzer Space Telescope
observations at 3-24 micron. We identify 153 distant red galaxies (DRGs) with
J-K > 2.3 mag (Vega) in the southern GOODS field. This sample is approximately
complete in stellar mass for passively evolving galaxies above 10^11 solar
masses and z < 3. The galaxies identified by this selection are roughly split
between objects whose optical and near-IR rest-frame light is dominated by
evolved stars combined with ongoing star formation, and galaxies whose light is
dominated by heavily reddened starbursts. Very few of the galaxies (< 10%) have
no indication of current star formation. Using SFR estimates that include the
reradiated IR emission, the DRGs at z=1.5-3 with stellar masses > 10^11 solar
masses have specific SFRs (SFRs per unit stellar mass) ranging from 0.2 to 10
Gyr^-1, with a mean value of ~2.4 Gyr^-1. The DRGs with stellar masses > 10^11
solar masses and 1.5 < z < 3 have integrated specific SFRs greater the global
value over all galaxies. In contrast, we find that galaxies at z = 0.3-0.75
with these stellar masses have integrated specific SFRs less than the global
value, and more than an order of magnitude lower than that for massive DRGs at
z = 1.5-3. At z < 1, lower-mass galaxies dominate the overall cosmic mass
assembly. This suggests that the bulk of star formation in massive galaxies
occurs at early cosmic epochs and is largely complete by z~1.5. [Abridged]


title: Spectrum of magnetohydrodynamic turbulence

abstract:
  We propose a phenomenological theory of strong incompressible
magnetohydrodynamic turbulence in the presence of a strong large-scale external
magnetic field. We argue that in the inertial range of scales, magnetic-field
and velocity-field fluctuations tend to align the directions of their
polarizations. However, the perfect alignment cannot be reached, it is
precluded by the presence of a constant energy flux over scales. As a
consequence, the directions of fluid and magnetic-field fluctuations at each
scale $\lambda$ become effectively aligned within the angle
$\phi_{\lambda}\propto \lambda^{1/4}$, which leads to scale-dependent depletion
of nonlinear interaction and to the field-perpendicular energy spectrum
$E(k_{\perp})\propto k_{\perp}^{-3/2}$. Our results may be universal, i.e.,
independent of the external magnetic field, since small-scale fluctuations
locally experience a strong field produced by large-scale eddies.


title: Bimodal Galaxies and Bimodality in Globular Cluster Systems

abstract:
  Various galaxy properties are not continuous over a large range in mass, but
rather reveal a remarkable transition or `bimodality' at a stellar mass of 3 x
10^{10} Mo. These properties include colors, stellar populations, Xray emission
and mass-to-light ratios. This behavior has been interpreted as the transition
from hot to cold flows by Dekel & Birnboim (2005).
  Here we explore whether globular cluster (GC) systems also reveal a bimodal
nature with regard to this critical mass scale. Globular clusters probe star
formation at early epochs in the Universe and survive subsequent galaxy mergers
and accretions. We use new data from the ACS Virgo Cluster Survey (Peng etal
2005), which provides a homogeneous sample of the GC systems around one hundred
Virgo early-type galaxies covering a range of five hundred in galaxy mass.
Their classification of the GC color distributions is taken to examine a key
quantity -- the number of GCs per unit galaxy luminosity. Below the critical
mass, this quantity (called the GC specific frequency) increases dramatically
in its mean value and spread. This increase may be due to regulated star
formation in low mass galaxies, which in turn is due to mass loss via winds and
the transition from hot to cold gas accretion flows. We also note that above
the critical mass, galaxies possess two GC subpopulations (with blue and red
mean colors) but below this mass, galaxies reveal an increasing proportion of
single (blue) GC systems.


title:
Millihertz Quasi-Periodic Oscillations from Marginally Stable Nuclear
  Burning on an Accreting Neutron Star

abstract:
  We investigate marginally stable nuclear burning on the surface of accreting
neutron stars as an explanation for the mHz quasi-periodic oscillations (QPOs)
observed from three low mass X-ray binaries. At the boundary between unstable
and stable burning, the temperature dependence of the nuclear heating rate and
cooling rate almost cancel. The result is an oscillatory mode of burning, with
an oscillation period close to the geometric mean of the thermal and accretion
timescales for the burning layer. We describe a simple one-zone model which
illustrates this basic physics, and then present detailed multizone
hydrodynamical calculations of nuclear burning close to the stability boundary
using the KEPLER code. Our models naturally explain the characteristic 2 minute
period of the mHz QPOs, and why they are seen only in a very narrow range of
X-ray luminosities. The oscillation period is sensitive to the accreted
hydrogen fraction and the surface gravity, suggesting a new way to probe these
parameters. A major puzzle is that the accretion rate at which the oscillations
appear in the theoretical models is an order of magnitude larger than the rate
implied by the X-ray luminosity when the mHz QPOs are seen. We discuss the
implications for our general understanding of nuclear burning on accreting
neutron stars. One possibility is that the accreted material covers only part
of the neutron star surface at luminosities Lx > ~1E37 erg/s.


title:
Accretion and nuclear activity of quiescent supermassive black holes. I:
  X-ray study

abstract:
  We have studied the nuclear activity in a sample of six quiescent early-type
galaxies, with new Chandra data and archival HST optical images. Their nuclear
sources have X-ray luminosities ~ 10^{38} - 10^{39} erg/s (L_X/L_Edd ~ 10^{-8}
- 10^{-7}), and colors or spectra consistent with accreting supermassive black
holes (SMBHs)--except for the nucleus of NGC 4486B, which is softer than
typical AGN spectra. In a few cases, the X-ray morphology of the nuclear
sources shows hints of marginally extended structures, in addition to the
surrounding diffuse thermal emission from hot gas, which is detectable on
scales >~ 1 kpc. In one case (NGC 5845), a dusty disk may partially obstruct
our direct view of the SMBH. We have estimated the temperature and density of
the hot interstellar medium, which is one major source of fuel for the
accreting SMBH; typical central densities are n_e ~ (0.02 +/- 0.01) cm^{-3}.
Assuming that the hot gas is captured by the SMBH at the Bondi rate, we show
that the observed X-ray luminosities are too faint to be consistent with
standard disk accretion, but brighter than predicted by radiatively-inefficient
solutions (eg, ADAF). In total, there are ~ 20 galaxies for which SMBH mass,
hot gas density, and nuclear X-ray luminosity are simultaneously known. In some
cases, the nuclear sources are brighter than predicted by the ADAF model; in
other cases, they are consistent or fainter. We discuss the apparent lack of
correlations between Bondi rate and X-ray luminosity, and suggest that, in
order to understand the observed distribution, we need to know two additional
parameters: the amount of gas supplied by the stellar population inside the
accretion radius, and the fraction (possibly << 1) of the total gas available
that is accreted by the SMBH. We shall discuss these issues in our Paper II.


title: A High-Mass Protobinary System in the Hot Core W3(H2O)

abstract:
  We have observed a high-mass protobinary system in the hot core W3(H2O) with
the BIMA Array. Our continuum maps at wavelengths of 1.4mm and 2.8mm both
achieve sub-arcsecond angular resolutions and show a double-peaked morphology.
The angular separation of the two sources is 1.19" corresponding to 2.43X10^3
AU at the source distance of 2.04 kpc. The flux densities of the two sources at
1.4mm and 2.8mm have a spectral index of 3, translating to an opacity law of
kappa ~ nu. The small spectral indices suggest that grain growth has begun in
the hot core. We have also observed 5 K components of the CH3CN (12-11)
transitions. A radial velocity difference of 2.81 km/s is found towards the two
continuum peaks. Interpreting these two sources as binary components in orbit
about one another, we find a minimum mass of 22 Msun for the system. Radiative
transfer models are constructed to explain both the continuum and methyl
cyanide line observations of each source. Power-law distributions of both
density and temperature are derived. Density distributions close to the
free-fall value, r^-1.5, are found for both components, suggesting continuing
accretion. The derived luminosities suggest the two sources have equivalent
zero-age main sequence (ZAMS) spectral type B0.5 - B0. The nebular masses
derived from the continuum observations are about 5 Msun for source A and 4
Msun for source C. A velocity gradient previously detected may be explained by
unresolved binary rotation with a small velocity difference.


title: About putative Neptune-like extrasolar planetary candidates

abstract:
  We re-analyze the precision radial velocity (RV) data of HD188015, HD114729,
HD190360, HD147513 and HD208487. All these stars are supposed to host Jovian
companions in long-period orbits. We test a hypothesis that the residuals of
the 1-planet model of the RV or an irregular scatter of the measurements about
the synthetic RV curve may be explained by the existence of additional planets
in short-period orbits. We perform a global search for the best fits in the
orbital parameters space with genetic algorithms and simplex method. This makes
it possible to verify and extend the results obtained with an application of
commonly used FFT-based periodogram analysis for identifying the leading
periods. Our analysis confirms the presence of a periodic component in the RV
data of HD190360 which may correspond to a hot-Neptune planet. We found four
new cases when the 2-planet model yields significantly better fits to the RV
data than the best 1-planet solutions. If the periodic variability of the
residuals of single-planet fits has indeed a planetary origin then hot-Neptune
planets may exist in these extrasolar systems. We estimate their orbital
periods in the range of 7-20d and minimal masses about of 20 masses od the
Earth.


title:
Spectroscopically Confirmed Large-Scale Structures Associated to a
  z=0.83 Cluster

abstract:
  (Abridged) We present a discovery of definitive large-scale structures around
RXJ0152.7--1352 at z=0.83 based on spectroscopic redshifts. In our previous
papers, we reported a photometric identification of the large-scale structures
at z~0.8. A spectroscopic follow-up observation was carried out on 8 selected
regions covering the most prominent structures to confirm their association to
the main cluster. In six out of the eight fields, a well isolated peak is
identified in the distribution of spectroscopic redshifts at or near the
cluster redshift. This is strong evidence for the presence of large-scale
structures associated to the main cluster at z=0.83. We then investigate
stellar populations of galaxies in the structures. The composite spectra are
constructed from a number of red member galaxies on the colour-magnitude
sequence. We consider three representative environments -- cluster, group, and
field. The ``cluster'' red galaxies do not show any sign of on-going or recent
star formation activities and the passive evolution can naturally link them to
the present-day red sequence galaxies in the Sloan Digital Sky Survey. In
contrast, the red galaxies in ``groups'' and in the ``field'' tend to show
signs of remaining and/or recent star formation activities characterized by
weak [OII] emissions and/or strong H delta absorptions. Our current data seem
to favour a scenario that star formation is truncated in a short time scale
(<1Gyr). This would imply that galaxy-galaxy interactions are responsible for
the truncation of star formation.


title:
A multiwavelength investigation of the temperature of the cold neutral
  medium

abstract:
  We present measurements of the H I spin temperatures (T_s) of the Cold
Neutral Medium (CNM) towards radio sources that are closely aligned with stars
for which published H_2 ortho-para temperatures (T_{01}) are available from UV
observations. Our sample consists of 18 radio sources close to 16 nearby stars.
The transverse separation of the lines of sight of corresponding the UV and
radio observations varies from 0.1 to 12.0 pc at the distance of the star. The
ultraviolet (UV) measurements do not have velocity information, so we use the
velocities of low ionization species (e.g Na I, K I, C I) observed towards
these same stars to make a plausible identification of the CNM corresponding to
the H_2 absorption. We then find that T_{01} and T_s match within observational
uncertainties for lines-of-sight with H_2 column density above 10^{15.8}
cm^{-2}, but deviate from each other below this threshold. This is consistent
with the expectation that in the CNM T_s tracks the kinetic temperature due to
collisions and that T_{01} is driven towards the kinetic temperature by proton
exchange reactions.


title:
Modal Filtering for Nulling Interferometry-First Single-Mode Conductive
  Waveguides in the Mid-Infrared

abstract:
  This paper presents the work achieved for the manufacturing and
characterization of first single-mode waveguides to be used as modal filters
for nulling interferometry in the mid-infrared range [4-20 um]. As very high
dynamic range is mandatory for detection of Earth-like planets, modal filtering
is one of the most stringent instrumental aspects. The hollow metallic
waveguides (HMW) presented here are manufactured using micro-machining
techniques. Single-mode behavior has been investigated in laboratory through a
technique of polarization analysis while transmission features have been
measured using flux relative comparison. The single-mode behavior have been
assessed at lambda=10.6 um for rectangular waveguides with dimensions a=10 um
and b<5.3 um with an accuracy of ~2.5 %. The tests have shown that a
single-polarization state can be maintained in the waveguide. A comparison with
results on multi-mode HMW is proposed. Excess losses of 2.4 dB (~ 58 %
transmission) have been measured for a single-mode waveguide. In particular,
the importance of coupling conditions into the waveguide is emphasized here.
The goal of manufacturing and characterizing the first single-mode HMW for the
mid-infrared has been achieved. This opens the road to the use of integrated
optics for interferometry in the mentioned spectral range.


title:
Formation of Magnetically Supported Disks During Hard-to-Soft Transition
  in Black Hole Accretion Flows

abstract:
  We carried out three-dimensional global resistive magnetohydrodynamic (MHD)
simulations of the cooling instability in optically thin hot black hole
accretion flows by assuming bremsstrahlung cooling. General relativistic
effects are simulated by using the pseudo-Newtonian potential. Cooling
instability grows when the density of the accretion disk becomes sufficiently
large. We found that as the instability grows the accretion flow changes from
an optically thin, hot, gas pressure-supported state (low/hard state) to a
cooler, magnetically supported, quasi-steady state. During this transition,
magnetic pressure exceeds the gas pressure because the disk shrinks in the
vertical direction almost conserving the toroidal magnetic flux. Since further
vertical contraction of the disk is suppressed by magnetic pressure, the cool
disk stays in an optically thin, spectrally hard state. In the magnetically
supported disk, the heating rate balances with the radiative cooling rate. The
magnetically supported disk exists for time scale much longer than the thermal
time scale and comparable to the accretion time scale.
  We examined the stability of the magnetically supported disk analytically,
assuming that the toroidal magnetic flux is conserved, and found it thermally
and secularly stable. Our findings may explain why black hole candidates stay
in luminous, X-ray hard state even when their luminosity exceeds the threshold
for the onset of the cooling instability.


title: Shear Viscosity and Oscillations of Neutron Star Crusts

abstract:
  We calculate the electron shear viscosity (determined by Coulomb electron
collisions) for a dense matter in a wide range of parameters typical for white
dwarf cores and neutron star crusts. In the density range from ~10^3 g cm^-3 to
10^7-10^10 g cm^-3 we consider the matter composed of widely abundant
astrophysical elements, from H to Fe. For higher densities, 10^10-10^14 g
cm^-3, we employ the ground-state nuclear composition, taking into account
finite sizes of atomic nuclei and the distribution of proton charge over the
nucleus. Numerical values of the viscosity are approximated by an analytic
expression convenient for applications. Using the approximation of
plane-parallel layer we study eigenfrequencies, eigenmodes and viscous damping
times of oscillations of high multipolarity, l~500-1000, localized in the outer
crust of a neutron star. For instance, at l~500 oscillations have frequencies f
>= 40 kHz and are localized not deeper than ~300 m from the surface. When the
crust temperature decreases from 10^9 K to 10^7 K, the dissipation time of
these oscillations (with a few radial nodes) decreases from ~1 year to 10-15
days.


title: X-ray and soft gamma-ray behaviour of the Galactic source 1E 1743.1-2843

abstract:
  The X-ray persistent source 1E 1743.1-2843, located in the Galactic Centre
region, has been detected by all X-ray telescope above 2 keV, whereas it is not
visible in the soft X-rays (i. e. Rosat) because of the high column density
along the line-of-sight. Moreover, the nature of this source remains still
unknown. The gamma-ray satellite INTEGRAL has long observed the Galactic Centre
region in the framework of the Core Programme. We report on results of two
years of INTEGRAL observations of 1E 1743.1--2843 detected for the first time
in the soft gamma-ray band. Since the source does not show any evidence for
strong variability, we present the broad-band spectral analysis using not
simultaneous XMM-Newton observations.


title: Variations in the spectral slope of Sgr A* during a NIR flare

abstract:
  We have observed a bright flare of Sgr A* in the near infrared with the
adaptive optics assisted integral field spectrometer SINFON. Within the
uncertainties, the observed spectrum is featureless and can be described by a
power law. Our data suggest that the spectral index is correlated with the
instantaneous flux and that both quantities experience significant changes
within less than one hour. We argue that the near infrared flares from Sgr A*
are due to synchrotron emission of transiently heated electrons, the emission
being affected by orbital dynamics and synchrotron cooling, both acting on
timescales of ~20 minutes.


title:
Some Consequences of Dark Energy Density varying Exponentially with
  Scale Factor

abstract:
  In this paper we have explored the consequences of a model of dark energy
with its energy density varying exponentially with the scale factor. We first
consider the model with $ \rho_{\phi} \propto e^{\kappa a} $, where $\kappa $
is a constant. This is a kind of generalisation of the cosmological constant
model with $\kappa = 0$. We show that such an exponentially varying dark energy
density with the scale factor naturally leads to an equivalent phantom field.
We also consider a model with $ \rho_{\phi} \propto e^{\kappa /a} $ and we show
that this also naturally leads to an equivalent phantom field.


title: A New Time-Symmetric Block Time-Step Algorithm for N-Body Simulations

abstract:
  Time-symmetric integration schemes share with symplectic schemes the property
that their energy errors show a much better behavior than is the case for
generic integration schemes. Allowing adaptive time steps typically leads to a
loss of symplecticity. In contrast, time symmetry can be easily maintained, at
least for a continuous choice of time step size. In large-scale N-body
simulations, however, one often uses block time steps, where all time steps are
forced to take on values as powers of two. This greatly facilitates
parallelization, and hence code efficiency. Straightforward implementation of
time-symmetry, translated to block time steps, faces significant hurdles. For
example, iteration can lead to oscillatory behavior, and even when such
behavior is suppressed, energy errors show a linear drift in time. We present
an approach that circumvents these problems.


title:
How well do we know the age and mass distributions of the star cluster
  system in the Large Magellanic Cloud?

abstract:
  [ABRIDGED] The LMC star cluster system offers the unique opportunity to
independently check the accuracy of age and mass determinations based on a
number of complementary techniques, including isochrone analysis. Using our
sophisticated tool for star cluster analysis based on broad-band spectral
energy distributions (SEDs), we reanalyse the Hunter et al. (2003) LMC cluster
photometry. Our main aim is to set the tightest limits yet on the accuracy of
ABSOLUTE age determinations based on broad-band SEDs, and therefore on the
usefulness of such an approach. Our broad-band SED fits yield reliable ages,
with statistical absolute uncertainties within Delta[log(Age/yr)] = 0.4
overall. The systematic differences we find with respect to previous age
determinations are caused by conversions of the observational photometry to a
different filter system. The LMC's cluster formation rate (CFR) has been
roughly constant outside of the well-known age gap between ~3 and 13 Gyr, when
the CFR was a factor of ~5 lower. We derive the characteristic cluster
disruption time-scale, log(t_4^dis/yr) = 9.9 +- 0.1, where t_dis = t_4^dis
(M_cl/10^4 Msun)^0.62. This long characteristic disruption time-scale implies
that we are observing the INITIAL cluster mass function (CMF). We conclude that
the youngest mass and luminosity-limited LMC cluster subsets show shallower
slopes than the slope of alpha = -2 expected (at least below masses of a few x
10^3 Msun), which is contrary to dynamical expectations. This may imply that
the initial CMF slope of the LMC cluster system as a whole is NOT well
represented by a power-law, although we cannot disentangle the unbound from the
bound clusters at the youngest ages.


title:
Multiperiodicity in the large-amplitude rapidly-rotating $\beta $Ceph ei
  star HD 203664

abstract:
  We perform a seismic study of the young massive $\beta $Cephei star HD 203664
with the goal to constrain its interior structure. Our study is based on a time
series of 328 new Geneva 7-colour photometric data of the star spread over
496.8 days. The data confirm the frequency of the dominant mode of the star
which we refine to $f_1=6.02885 $c d$^{-1}$. The mode has a large amplitude of
37 mmag in V and is unambiguously identified as a dipole mode ($\ell=2$) from
its amplitude ratios and non-adiabatic computations. Besides $f_1$, we discover
two additional new frequencies in the star with amplitudes above $4\sigma$:
$f_2=6.82902 $c d$^{-1}$ and $f_3=4.81543 $c d$^{-1}$ or one of their daily
aliases. The amplitudes of these two modes are only between 3 and 4 mmag which
explains why they were not detected before. Their amplitude ratios are too
uncertain for mode identification. We show that the observed oscillation
spectrum of HD 203664 is compatible with standard stellar models but that we
have insufficient information for asteroseismic inferences. Among the
large-amplitude $\beta $Cephei stars, HD 203664 stands out as the only one
rotating at a significant fraction of its critical rotation velocity ($\sim
40%$).


title:
The SAURON project - V. Integral-field emission-line kinematics of 48
  elliptical and lenticular galaxies

abstract:
  We present the emission-line fluxes and kinematics of 48 representative
elliptical and lenticular galaxies obtained with our custom-built
integral-field spectrograph SAURON. Hb, [OIII], and [NI] emission lines were
measured using a new procedure that simultaneously fits both the stellar
spectrum and the emission lines. Using this technique we can detect emission
lines down to an equivalent width of 0.1A set by the current limitations in
describing galaxy spectra with synthetic and real stellar templates, rather
than by the quality of our spectra. Emission is detected in 75% of our sample
galaxies, and comes in a variety of resolved spatial distributions and
kinematic behaviours. The ionised-gas kinematics is rarely consistent with
simple coplanar circular motions. However, the gas almost never displays
completely irregular kinematics, generally showing coherent motions with smooth
variations in angular momentum. In the majority of the cases the gas kinematics
is decoupled from the stellar kinematics, and in half of the objects this
decoupling implies a recent acquisition of gaseous material. Over the entire
sample however, the distribution of the mean misalignment values between
stellar and gaseous angular momenta is inconsistent with a purely external
origin. Consistent with previous studies, the presence of dust features is
always accompanied by gas emission while the converse is not always true. A
considerable range of values for the [OIII]/Hb ratio is found both across the
sample and within single galaxies. Despite the limitations of this ratio as an
emission-line diagnostic, this finding suggests either that a variety of
mechanisms is responsible for the gas excitation in E and S0 galaxies or that
the metallicity of the interstellar material is quite heterogeneous.


title: Scalar statistics on the sphere: application to the CMB

abstract:
  A method to compute several scalar quantities of Cosmic Microwave Background
maps on the sphere is presented. We consider here four type of scalars: the
Hessian matrix scalars, the distortion scalars, the gradient related scalars
and the curvature scalars. Such quantities are obtained directly from the
spherical harmonic coefficients (alm) of the map. We also study the probability
density function of these quantities for the case of a homogeneous and
isotropic Gaussian field, which are functions of the power spectrum of the
initial field. From these scalars it is posible to construct a new set of
scalars which are independent of the power spectrum of the field. We test our
results using simulations and find a good agreement between the theoretical
probability density functions and those obtained from simulations. Therefore,
these quantities are proposed to investigate the presence of non-Gaussian
features in CMB maps. Finally, we show how to compute the scalars in presence
of anisotropic noise and realistic masks.


title: The radial profiles of the different mass components in galaxy clusters

abstract:
  AIMS. To derive the mass profiles of the different luminous and dark
components in clusters. METHODS. The cluster mass profile is determined by
using the Jeans equation applied to the projected phase-space distribution of
about 3000 galaxies members of 59 nearby clusters from the ESO Nearby Abell
Cluster Survey. The baryonic and subhaloes mass components are determined from
the galaxies' luminosity-density profiles through scaling relations between
luminosities and baryonic and dark halo masses. The baryonic mass component
associated to the intra-cluster gas is determined using X-ray data from ROSAT.
RESULTS. The baryon-to-total mass fraction decreases from a value of 0.12 near
the center, to 0.08 at the distance of 0.15 virial radii, then it increases
again, to reach a value of 0.14 at the virial radius. Diffuse, cluster-scale,
dark matter dominates at all radii, but its contribution to the total mass
content decreases outwards to the virial radius, where the dark matter in
subhaloes may contribute up to 23 %, and the baryons 14 %, of the total mass.
The dark mass, and diffuse dark mass profiles are well fit by both cuspy and
cored models. The subhaloes mass distribution is not fit by either model.


title:
X-RED: A Satellite Mission Concept To Detect Early Universe Gamma Ray
  Bursts

abstract:
  Gamma ray bursts (GRBs) are the most energetic eruptions known in the
Universe. Instruments such as Compton-GRO/BATSE and the GRB monitor on BeppoSAX
have detected more than 2700 GRBs and, although observational confirmation is
still required, it is now generally accepted that many of these bursts are
associated with the collapse of rapidly spinning massive stars to form black
holes. Consequently, since first generation stars are expected to be very
massive, GRBs are likely to have occurred in significant numbers at early
epochs. X-red is a space mission concept designed to detect these extremely
high redshifted GRBs, in order to probe the nature of the first generation of
stars and hence the time of reionisation of the early Universe. We demonstrate
that the gamma and x-ray luminosities of typical GRBs render them detectable up
to extremely high redshifts (z~10-30), but that current missions such as HETE2
and SWIFT operate outside the observational range for detection of high
redshift GRB afterglows. Therefore, to redress this, we present a complete
mission design from the science case to the mission architecture and payload,
the latter comprising three instruments, namely wide field x-ray cameras to
detect high redshift gamma-rays, an x-ray focussing telescope to determine
accurate coordinates and extract spectra, and an infrared spectrograph to
observe the high redshift optical afterglow. The mission is expected to detect
and identify for the first time GRBs with z > 10, thereby providing constraints
on properties of the first generation of stars and the history of the early
Universe.


title:
Subaru optical observations of the two middle-aged pulsars PSR B0656+14
  and Geminga

abstract:
  We carried out a deep subarcsecond BRI imaging of the two middle-aged pulsars
to establish their properties in the optical range. Both pulsars are detected
at >10 sigma level. Geminga is for the first time reliably detected in the I
band with a magnitude of 25.10+/-0.14. We also reanalyze archival ESO/NTT and
HST broadband data and find that some published fluxes for Geminga were
estimated inaccurately. The resulting dereddened broadband spectra of both
pulsars are remarkably similar to each other and show significant flux
increases towards the far-UV and near-IR, and a wide flux excess in V-I bands.
This suggests a multicomponent structure of the optical emission. The
nonthermal power law component of the pulsar magnetospheric origin dominates in
the most part of the optical range. For PSR B0656+14 it is compatible with a
low energy extension of the power law tail seen in hard X-rays. For Geminga the
respective extension overshoots by a factor of 100 the nonthermal optical flux,
which has a less steep spectral slope than in X-rays. This implies a spectral
break at a photon energy of about 1 keV. The flux increases towards the far-UV
are compatible with contributions of the Rayleigh-Jeans parts of the blackbody
components from whole surfaces of the neutron stars dominating in soft X-rays.
The V-I excess, which is most significant for PSR B0656+14, suggests a third
spectral component of still unidentified origin. Faint, a few arcseconds in
size nebulae extended perpendicular to the proper motion directions of the
pulsars, are seen around both objects in our deepest I band images. They can be
optical counterparts of the bow-shock head of Geminga and of the tentative
pulsar wind nebula of PSR B0656+14 observed in X-rays.


title:
Steady shocks around black holes produced by sub-keplerian flows with
  negative energy

abstract:
  We discuss a special case of formation of axisymmetric shocks in the
accretion flow of ideal gas onto a Schwarzschild black hole: when the total
energy of the flow is negative. The result of our analysis enlarges the
parameter space for which these steady shocks are exhibited in the accretion of
gas rotating around relativistic stellar objects. Since keplerian disks have
negative total energy, we guess that, in this energy range, the production of
the shock phenomenon might be easier than in the case of positive energy. So
our outcome reinforces the view that sub-keplerian flows of matter may
significantly affect the physics of the high energy radiation emission from
black hole candidates. We give a simple procedure to obtain analytically the
position of the shocks. The comparison of the analytical results with the data
of 1D and 2D axisymmetric numerical simulations confirms that the shocks form
and are stable.


title:
Structure formation and CMBR anisotropy spectrum in the inflessence
  model

abstract:
  The inflessence model has recently been proposed in an attempt to explain
both early inflation and present day accelerated expansion within a single
mechanism. The model has been successfully tested against the Hubble diagram of
Type Ia Supernovae, the shift parameter, and the acoustic peak parameter. As a
further mandatory test, we investigate here structure formation in the
inflessence model determining the evolution of matter density contrast $\delta
\equiv \delta \rho_M/\rho_M$ in the linear regime. We compare the growth factor
$D(a) \equiv \delta/a$ and the growth index $f(z) \equiv d\ln{\delta}/d\ln{a}$
to these same quantities for the successful concordance $\Lambda$CDM model with
a particular emphasis on the role of the inflessence parameters $(\gamma,
z_Q)$. We also evaluate the anisotropy spectrum of the cosmic microwave
background radiation (CMBR) to check whether the inflessence model may be in
agreement with the observations. We find that, for large values of $(\gamma,
z_Q)$, structure formation proceeds in a similar way to that in the
$\Lambda$CDM scenario, and it is also possible to nicely fit the CMBR spectrum.


title: Spitzer/IRAC Photometry of the Eta Chameleontis Association

abstract:
  We present IRAC 3.6, 4.5, 5.8 and 8 micron photometry for the 17 A, K and M
type members of the Eta Chameleontis association. These data show infrared
excesses toward six of the 15 K and M stars, indicating the presence of
circumstellar disks around 40% of the stars with masses of 0.1-1 solar mass.
The two A-stars show no infrared excesses. The excess emission around one of
the stars is comparable to the median excess for classical T Tauri stars in the
Taurus association; the remaining five show comparatively weak excess emission.
Taking into account published Halpha spectroscopy that shows that five of the
six stars are accreting, we argue that the disks with weak mid-infrared
excesses are disks in which the inner disks have been largely depleted of small
grains by grain growth, or, in one case, the small grains have settled to the
midplane. This suggests that Eta Cha has a much higher fraction of disks caught
in the act of transitioning into optically thin disks than that measured in
younger clusters and associations.


title: The nature of the HE0450-2958 System

abstract:
  Magain et al. (2005) argued that the host galaxy of the quasar in HE0450-2958
is substantially under-luminous given the likely mass of its nuclear black
hole. Using kinematical information from the spectra of the quasar and the
companion galaxy, an ultra-luminous infrared galaxy, we test the hypothesis
that the black hole powering the quasar was ejected from the companion galaxy
during a merger. We find that the ejection model can be securely ruled out,
since the kick velocity required to remove the black hole from the galaxy is
greater than about 500 km/s, inconsistent with the presence of narrow emission
line gas at the same redshift as the quasar nucleus. We also show that the
quasar in HE0450-2958 has the spectral characteristics of a narrow-line Seyfert
1 galaxy and calculate a mass for its black hole that is roughly an order of
magnitude smaller than estimated by Magain et al. The predicted luminosity of
the host galaxy is then consistent with the upper limits inferred by those
authors.


title:
Crossing of the Cosmological Constant Boundary - an Equation of State
  Description

abstract:
  The phenomenon of the dark energy transition between the quintessence regime
($w > -1$) and the phantom regime ($w < -1$), also known as the cosmological
constant boundary crossing, is analyzed in terms of the dark energy equation of
state. It is found that the dark energy equation of state in the dark energy
models which exhibit the transition is {\em implicitly} defined. The
generalizations of the the models explicitly constructed to exhibit the
transition are studied to gain insight into the mechanism of the transition. It
is found that the cancellation of the terms corresponding to the cosmological
constant boundary makes the transition possible.


title: Red AGN in XMM-Newton/SDSS fields

abstract:
  In this paper we combine archival and proprietary XMM-Newton observations
(about 5deg^2) that overlap with the Sloan Digital Sky Survey to explore the
nature of the moderate-z X-ray population. We focus on X-ray sources with
optically red colours (g-r>0.4), which we argue are important for understanding
the origin of the X-ray background. Firstly, these systems constitute a
significant fraction, about 2/3, of the z<1 X-ray population to the limit
f(2-8keV)~2e-14cgs. Secondly, their luminosity function under evolution of the
form ~(1+z)^3 suggests that they could be responsible for about 17 per cent of
the diffuse X-ray background to z=1. Thirdly, their stacked X-ray spectrum in
the range 1-8keV is consistent with a power-law distribution with Gamma~1.4
(without fitting intrinsic absorption), i.e. similar to the diffuse X-ray
background. We find that the optically red X-ray population comprises a mixed
bag of objects, both obscured (N_H>1e22 cm^{-2}) and unobscured (N_H<1e22
cm^{-2}), with a wide range of X-ray luminosities up L_X~1e44cgs. We argue that
dilution of the AGN light by the host galaxy may play a role in shaping the
continuum optical emission of this population. Finally, we explore a possible
association of these sources and the moderate-z red (J-Ks>2mag) AGNs identified
in the Two Micron All Sky Survey (2MASS). The median N_H of the red X-ray
sources studied here is ~1e21cm^{-2}, lower than that found for the 2MASS AGNs,
suggesting different populations.


title:
Uncovering Planetary Nebulae in Early Type Galaxies using the Rutgers
  Fabry-Perot

abstract:
  We report on observations of four early-type galaxies performed with the
Rutgers Fabry-Perot in order to search for Planetary Nebulae (PNe) in these
systems. The aim is to use the PNe as kinematic tracers of the galaxy
potential. We describe our data reduction and analysis procedure and show that
the proper calibration of our detection statistic is crucial in getting down to
our limiting magnitude of $m_{5007} = 26.1$. In the case of the two Leo
galaxies we find moderately sized samples: 54 PNe in NGC 3379 and 50 PNe in NGC
3384; NGC 4636 (2 PNe) and NGC 1549 (6 PNe) are included for completeness. We
present our samples in tabular form, as well as the spectrum for each PN. We
constructed simple non-parametric spherical mass models for NGC 3379 using a
Monte Carlo Markov Chain method to explore the space of likely mass models. We
find a remarkably constant mass-to-light ratio within five half-light radii
with an overall $B$ band mass-to-light ratio $\sim 5$. A simple mass-to-light
estimate for NGC 3384 yields $\Upsilon_B \sim 11$, but is likely an
overestimate.


title: High-resolution Millimeter Imaging of Submillimeter Galaxies

abstract:
  We present sub-arcsecond resolution IRAM PdBI interferometry of eight
submillimeter galaxies at redshifts from 2 to 3.4, where we detect continuum at
1mm and/or CO lines at 3 and 1 mm. The CO 3-2/4-3 line profiles in five of the
sources are double-peaked, indicative of orbital motion either in a single
rotating disk or of a merger of two galaxies. The millimeter line and continuum
emission is compact; we marginally resolve the sources or obtain tight upper
limits to their intrinsic sizes in all cases. The median FWHM diameter for
these sources and the previously resolved sources, SMMJ023952-0136 and
SMMJ140104+0252 is less than or equal to 0.5" (4 kpc). The compactness of the
sources does not support a scenario where the far-IR/submm emission comes from
a cold, very extended dust distribution. These measurements clearly show that
the submillimeter galaxies we have observed resemble scaled-up and more gas
rich versions of the local Universe, ultra-luminous galaxy (ULIRG) population.
Their central densities and potential well depths are much greater than in
other redshift 2-3 galaxy samples studied so far. They are comparable to those
of elliptical galaxies or massive bulges. The SMG properties fulfill the
criteria of 'maximal' starbursts, in which most of the available initial gas
reservoir of 10^10-10^11 solar masses is converted to stars on a few dynamical
timescales.


title:
Radio Spectra of three Supernova Remnants: G114.3+0.3, G116.5+1.1 and
  G116.9+0.2

abstract:
  New images of the Supernova Remnants (SNRs) G114.3+0.3, G116.5+1.1 and
G116.9+0.2 (CTB 1) are presented at 408 MHz from the Canadian Galactic Plane
Survey (CGPS). We also use the 1420 MHz images from the CGPS to study their
408-1420 MHz spectral indices. The flux densities at 408 MHz and 1420 MHz,
corrected for flux densities from compact sources within the SNRs, are 12$\pm$6
Jy and 9.8$\pm$0.8 Jy for G114.3+0.3, 15.0$\pm$1.5 Jy and 10.6$\pm$0.6 Jy for
G116.5+1.1, 15.0$\pm$1.5 Jy and 8.1$\pm$0.4 Jy for G116.9+0.2. The integrated
flux density-based spectral indices (S$_{\nu}$$\propto$$\nu$$^{-\alpha}$) are
$\alpha$=0.16$\pm$0.41, 0.28$\pm$0.10 and 0.49$\pm$0.09 for G114.3+0.3,
G116.5+1.1 and G116.9+0.2, respectively. Their T-T plot-based spectral indexes
are 0.68$\pm$0.48, 0.28$\pm$0.15, and 0.48$\pm$0.04, in agreement with the
integrated flux density-based spectral indices. New flux densities are derived
at 2695 MHz which are significantly larger than previous values. The new 408,
1420 and 2695 MHz flux densities and published values at other frequencies,
where images are not available, are fitted after correcting for contributions
from compact sources, to derive their multi-frequency spectral indices.


title: HE 0437-5439 -- an unbound hyper-velocity main-sequence B-type star

abstract:
  We report the discovery of a 16th magnitude star, HE0437-5439, with a
heliocentric radial velocity of +723+-3km/s. A quantitative spectral analysis
of high-resolution optical spectra obtained with the VLT and the UVES
spectrograph shows that HE0437-5439 is a main sequence B-type star with
Teff=20350K, log g=3.77, solar within a factor of a few helium abundance and
metal content, rotating at v sin i=54km/s. Using appropriate evolutionary
tracks we derive a mass of 8 Msun and a corresponding distance of 61 kpc. Its
galactic rest frame velocity is at least 563km/s, almost twice the local
Galactic escape velocity, indicating that the star is unbound to the Galaxy.
Numerical kinematical experiments are carried out to constrain its place of
birth. It has been suggested that such hyper-velocity stars can be formed by
the tidal disruption of a binary through interaction with the super-massive
black hole at the Galactic center (GC). HE0437-5439 needs about 100Myrs to
travel from the GC to its presentposition, much longer than its main sequence
lifetime of 25Myrs. This can only be reconciled if HE0437-5439 is a blue
straggler star. In this case, the predicted proper motion is so small that it
can only be measured by future space missions. Since the star is much closer to
the Large Magellanic Cloud (LMC, 18kpc) than to the GC, it can reach its
position from the center of the LMC. The proper motion predicted in this case
is about 2mas/y (relative to the LMC), large enough to be measurable with
conventional techniques from the ground. The LMC origin could also be tested by
a high-precision abundance analysis.


title: First Results from the Swift UVOT

abstract:
  We review some of the initial data from the UVOT telescope on the Swift
observatory. Statistics based on about six months of data suggest a dark burst
fraction of about 50% when combining both UVOT and ground-based observations.
There is evidence that some bursts have a large gamma-ray efficiency, which may
be due to strong magnetic fields in their ejecta. The bright GRB050525A shows
behaviour broadly consistent with expectations from the simple fireball model
for bursts, including evidence for a reverse shock component in the UVOT data,
and an achromatic break in decay slope indicative of a jet break. Other bursts
observed with Swift have a shallow decay initially which is difficult to
reconcile with the simple model. Replenishment of the forward shock energy by
continued ejection of material from the central engine, or initial injection of
material with a range of velocities, offers a potential explanation. In the
case of the XRF050406 an initially rising optical afterglow flux followed by a
shallow decay may be due to observation of a structured jet from a significant
off-axis angle.


title: US 708 - An unbound hyper-velocity subluminous O star

abstract:
  We report the discovery of an unbound hyper-velocity star, US 708, in the
Milky Way halo, with a heliocentric radial velocity of +708+-15km/s. A
quantitative NLTE model atmosphere analysis of optical spectra obtained with
LRIS at the Keck I telescope shows that US 708 is an extremely helium-rich
(N(He)/N(H)=10) subluminous O type star with Teff=44500K, log g=5.23 at a
distance of 19kpc. Its Galactic rest frame velocity is at least 751km/s, much
higher than the local Galactic escape velocity indicating that the star is
unbound to the Galaxy. It has been suggested that such hyper-velocity stars can
be formed by the tidal disruption of a binary through interaction with the
super-massive black hole (SMBH) at the Galactic centre (GC). Numerical
kinematical experiments are carried out to reconstruct the path from the GC.U S
708 needs about 32Myrs to travel from the GC to its present position, less than
its evolutionary lifetime. Its predicted proper motion mue(alpha)
cos(delta)=-2.3mas/y and mue(delta)=-2.4mas/y should be measurable by future
space missions. We conjecture that US 708 is formed by the merger of two helium
white dwarfs in a close binary induced by the interaction with the SMBH in the
GC and then escaped.


title: Dynamic Tides in Close Binaries

abstract:
  The basic theory of dynamic tides in close binaries is reviewed. Particular
attention is paid to resonances between dynamic tides and free oscillation
modes and to the role of the apsidal-motion rate in probing the internal
structure of binary components. The discussed effects are generally applicable
to stars across the entire Hertzsprung-Russell diagram, including the binary
OB-stars discussed at this meeting.


title: Turbulent Mixing in the Outer Solar Nebula

abstract:
  The effects of turbulence on the mixing of gases and dust in the outer Solar
nebula are examined using 3-D MHD calculations in the shearing-box
approximation with vertical stratification. The turbulence is driven by the
magneto-rotational instability. The magnetic and hydrodynamic stresses in the
turbulence correspond to an accretion time at the midplane about equal to the
lifetimes of T Tauri disks, while accretion in the surface layers is thirty
times faster. The mixing resulting from the turbulence is also fastest in the
surface layers. The mixing rate is similar to the rate of radial exchange of
orbital angular momentum, so that the Schmidt number is near unity. The
vertical spreading of a trace species is well-matched by solutions of a damped
wave equation when the flow is horizontally-averaged. The damped wave
description can be used to inexpensively treat mixing in 1-D chemical models.
However, even in calculations reaching a statistical steady state, the
concentration at any given time varies substantially over horizontal planes,
due to fluctuations in the rate and direction of the transport. In addition to
mixing species that are formed under widely varying conditions, the turbulence
intermittently forces the nebula away from local chemical equilibrium. The
different transport rates in the surface layers and interior may affect
estimates of the grain evolution and molecular abundances during the formation
of the Solar system.


title: Speckle nulling with space-based coronagraphs

abstract:
  Following the tracks of Malbet, Yu, & Shao (1995} on dark hole algorithms, we
present analytical methods to measure and correct the speckle noise behind an
ideal coronagraph. We show that, in a low aberration regime, wavefront sensing
can be accomplished with only three images, the next image being fully
corrected (no iterative process needed). The only hardware required is the
coronagraph deformable mirror and an imaging detector in the focal plane, thus
there are no non-common path errors to correct. Our first method, speckle field
nulling, is a fast FFT-based algorithm requiring the deformable mirror
influence functions to have identical shapes. Our second method, speckle energy
minimization is more general and based on matrix inversion. Numerical
simulations show that these methods can improve the contrast by several orders
of magnitude.


title: Six Years of Chandra Observations of Supernova Remnants

abstract:
  We present a review of the first six years of Chandra X-ray Observatory
observations of supernova remnants. From the official "first-light" observation
of Cassiopeia A that revealed for the first time the compact remnant of the
explosion, to the recent million-second spectrally-resolved observation that
revealed new details of the stellar composition and dynamics of the original
explosion, Chandra observations have provided new insights into the supernova
phenomenon. We present an admittedly biased overview of six years of these
observations, highlighting new discoveries made possible by Chandra's unique
capabilities.


title:
Mid-Infrared Emission from Elliptical Galaxies: Sensitivity to Stellar
  Age

abstract:
  Mid-infrared observations (3.6 - 24 microns) of normal giant elliptical
galaxies with the Spitzer space telescope are consistent with pure populations
of very old stars with no evidence of younger stars. Most of the stars in giant
elliptical galaxies are old but the mean stellar age determined from Balmer
absorption in optical spectra can appear much younger due to a small admixture
of younger stars. The mean stellar age can also be determined from the spectral
energy distribution in the mid-infrared which decreases with time relative to
the optical emission and shifts to shorter wavelengths. The observed flux
ratios F_8um/F_3.6um and F_24um/F_3.6um for elliptical galaxies with the oldest
Balmer line ages are lower than predicted by recent models of single stellar
populations. For ellipticals with the youngest Balmer line ages in our sample,
3-5 Gyrs, the flux ratios F_24um/F_3.6um are identical to those of the oldest
stars. When theoretical mid-IR spectra of old (12 Gyr) and young stellar
populations are combined, errors in the F_24um/F_3.6um observations are
formally inconsistent with a mass fraction of young stars that exceeds ~1%.
This is less than the fraction of young stars expected in discussions of recent
surveys of elliptical galaxies at higher redshifts. However, this inconsistancy
between Balmer line ages and those inferred from mid-IR observations must be
regarded as provisional until more accurate observations and theoretical
spectra become available. Finally, there is no evidence to date that central
disks or patches of dust commonly visible in optical images of elliptical
galaxies contribute sensibly to the mid-IR spectrum.


title: CNO in evolved intermediate mass stars

abstract:
  In order to investigate the possible influence of rotation on the efficiency
of the first dredge-up we determined atmospheric parameters, masses, and
abundances of carbon, nitrogen, and oxygen in a sample of evolved intermediate
mass stars. We used high resolution spectra and conducted a model atmosphere
analysis. The abundances were calculated through spectral synthesis and
compared to the predictions of rotating and non-rotating evolutionary models.
Almost all those objects in our sample where carbon and nitrogen abundances
could be determined show signs of internal mixing. The stars, however, seem to
be mixed to different extents. Among the mixed stars we identify five in our
sample with abundances in agreement with the non-rotating models, four stars
that seem to be mixed beyond that, and one star that seems to be slightly less
mixed than predicted for the first dredge-up. There are also five stars that
seem to be slightly more mixed than expected, but their abundances are in
marginal agreement with both rotating and non-rotating models. Such differences
in the extent of the mixing are not predicted by the standard models and imply
the action of other mixing mechanisms than solely the convective dredge-up. We
also identified for the first time an important correlation between the [N/C]
ratio and the stellar mass.


title: Mass Distributions of HST Galaxy Clusters from Gravitational Arcs

abstract:
  Although N-body simulations of cosmic structure formation suggest that dark
matter halos have density profiles shallower than isothermal at small radii and
steeper at large radii, whether observed galaxy clusters follow this profile is
still ambiguous. We use one such density profile, the asymmetric NFW profile,
to model the mass distributions of 11 galaxy clusters with gravitational arcs
observed by HST. We characterize the galaxy lenses in each cluster as NFW
ellipsoids, each defined by an unknown scale convergence, scale radius,
ellipticity, and position angle. For a given set of values of these parameters,
we compute the arcs that would be produced by such a lens system. To define the
goodness of fit to the observed arc system, we define a chi^2 function
encompassing the overlap between the observed and reproduced arcs as well as
the agreement between the predicted arc sources and the observational
constraints on the source system. We minimize this chi^2 to find the values of
the lens parameters that best reproduce the observed arc system in a given
cluster. Here we report our best-fit lens parameters and corresponding mass
estimates for each of the 11 lensing clusters. We find that cluster mass models
based on lensing galaxies defined as NFW ellipsoids can accurately reproduce
the observed arcs, and that the best-fit parameters to such a model fall within
the reasonable ranges defined by simulations. These results assert NFW profiles
as an effective model for the mass distributions of observed clusters.


title:
The maximum stellar mass, star-cluster formation and composite stellar
  populations

abstract:
  We demonstrate that the mass of the most massive star in a cluster correlates
non-trivially with the cluster mass. A simple algorithm according to which a
cluster is filled up with stars that are chosen randomly from the standard IMF
but sorted with increasing mass yields an excellent description of the
observational data. Algorithms based on random sampling from the IMF without
sorted adding are ruled out with a confidence larger than 0.9999. A physical
explanation of this would be that a cluster forms by more-massive stars being
consecutively added until the resulting feedback energy suffices to revert
cloud contraction and stops further star formation. This has important
implications for composite populations. For example, 10^4 clusters of mass 10^2
Msol will not produce the same IMF as one cluster with a mass of 10^6 Msol. It
also supports the notion that the integrated galaxial IMF (IGIMF) should be
steeper than the stellar IMF and that it should vary with the star-formation
rate of a galaxy.