title:
Cooling of Quark Stars in the Color Superconductive Phase: Effect of
  Photons from Glueball decay

abstract:
  The cooling history of a quark star in the color superconductive phase is
investigated. Here we specifically focus on the 2-flavour color (2SC) phase
where novel process of photon generation via glueball (GLB) decay have been
already investigated (Ouyed & Sannino 2001). The picture we present here can in
principle be generalized to quark stars entering a superconductive phase where
similar photon generation mechanisms are at play. As much as 10^{45}-10^{47}
erg of energy is provided by the GLB decay in the 2SC phase. The generated
photons slowly diffuse out of the quark star keeping it hot and radiating as a
black-body (with possibly a Wien spectrum in gamma-rays) for millions of years.
We discuss hot radio-quiet isolated neutron stars in our picture (such as RX
J185635-3754 and RX J0720.4-3125) and argue that their nearly blackbody spectra
(with a few broad features) and their remarkably tiny hydrogen atmosphere are
indications that these might be quark stars in the color superconductive phase
where some sort of photon generation mechanism (reminiscent of the GLB decay)
has taken place. Fits to observed data of cooling compact stars favor models
with superconductive gaps of Delta_2SC = 15-35 MeV and densities
rho_2SC=(2.5-3.0)rho_N (rho_N being the nuclear matter saturation density) for
quark matter in the 2SC phase. If correct, our model combined with more
observations of isolated compact stars could provide vital information to
studies of quark matter and its exotic phases.


title: The H I opacity of the intergalactic medium at redshifts 1.6 < z < 3.2

abstract:
  We use high quality echelle spectra of 24 QSOs to provide a calibrated
measurement of the total amount of Lyman-alpha forest absorption (DA) over the
redshift range 2.2 < z < 3.2. Our measurement of DA excludes absorption from
metal lines or the Lyman-alpha lines of Lyman limit systems and damped
Lyman-alpha systems. We use artificial spectra with realistic flux calibration
errors to show that we are able to place continuum levels that are accurate to
better than 1%. When we combine our results with our previous results between
1.6 < z < 2.2, we find that the redshift evolution of DA is well described over
1.6 < z < 3.2 as A*(1+z)^gamma, where A = 0.0062 and gamma = 2.75. We detect no
significant deviations from a smooth power law evolution over the redshift
range studied. We find less H I absorption than expected at z=3, implying that
the UV background is about 40% higher than expected. Our data appears to be
consistent with an H I ionization rate of Gamma ~ 1.4E-12 1/s.


title: MgII Absorption through Intermediate Redshift Galaxies

abstract:
  The current status and remaining questions of MgII absorbers are reviewed
with an eye toward new results incorporating high quality Hubble Space
Telescope images of the absorbing galaxies. In the end, we find that our
current picture of extended gaseous regions around galaxies at earlier epochs
is in need of some revision; MgII absorbing "halos" appear to be patchier and
their geometry less regular than previously inferred. We also find that the
so-called "weak" MgII absorbers are associated with normal galaxies over a wide
range of impact parameters, suggesting that this class of absorber does not
strictly select low surface brightness, dwarf galaxies, or IGM material. We
emphasize the need for a complete survey of the galaxies in quasar fields, and
the importance of obtaining rotation curves of confirmed absorbing galaxies.


title:
BhaBAR: Big Halpha kinematical sample of BARred spiral galaxies - I.
  Fabry-Perot Observations of 21 galaxies

abstract:
  The Halpha gas kinematics of twenty-one representative barred spiral galaxies
belonging to the BHaBAR sample is presented. The galaxies were observed with
FaNTOmM, a Fabry-Perot integral-field spectrometer, on three different
telescopes. The 3D data cubes were processed through a robust pipeline with the
aim of providing the most homogeneous and accurate dataset possible useful for
further analysis. The data cubes were spatially binned to a constant
signal-to-noise ratio, typically around 7. Maps of the monochromatic Halpha
emission line and of the velocity field were generated and the kinematical
parameters were derived for the whole sample using tilted-ring models. The
photometrical and kinematical parameters (position angle of the major axis,
inclination, systemic velocity and kinematical centre) are in relative good
agreement, except maybe for the later-type spirals.


title:
Spectral and morphological properties of quasar hosts in SPH simulations
  of AGN feeding by mergers

abstract:
  We present a method for generating virtual observations from
smoothed-particle-hydrodynamics (SPH) simulations. This method includes stellar
population synthesis models and the reprocessing of starlight by dust to
produce realistic galaxy images. We apply this method and simulate the merging
of two identical giant Sa galaxies. The merger remnant is an elliptical galaxy.
The merger concentrates the gas content of the two galaxies into the nuclear
region. The gas that flows into the nuclear region refuels the central black
holes of the merging galaxies. We follow the refuelling of the black holes
during the merger semi-analytically.
  In the simulation presented in this article, the black holes grow from 3 x
10^7 to 1.8X 10^8 Solar masses, with a peak AGN luminosity of M_B ~ -23.7. We
study how the morphological and spectral properties of the system evolve during
the merger and work out the predictions of this scenario for the properties of
host galaxies during the active phase. The peak of AGN activity coincides with
the merging of the two galactic nuclei and occurs at a stage when the remnant
looks like a lenticular galaxy. The simulation predicts the formation of a
circumnuclear starburst ring/dusty torus with an opening angle of 30-40 degrees
and made of clouds with n_H=10^24 cm^-2. The average optical depth of the torus
is quite high, but the obscuring medium is patchy, so that there still exist
lines of sight where the AGN is visible in a nearly edge-on view. For the same
reason, there are lines of sight where the AGN is completely obscured in the
face-on view.


title: Observation of the giant radio galaxy M87 at TeV energies with H.E.S.S

abstract:
  The giant radio galaxy M 87 was observed at TeV energies with the Cherenkov
telescopes of the H.E.S.S. collaboration (High Energy Stereoscopic System). The
observations have been performed in the year 2003 during the comissioning phase
and in 2004 with the full four telescope setup. The observations were motivated
by the measurement of the HEGRA collaboration which reported a 4.7 sigma excess
of TeV gamma-rays from the direction of M 87. The results of the H.E.S.S.
observations - indicating a possible variability of TeV gamma-ray emission from
M 87 (compared to the HEGRA result) - are presented.


title:
Accretion Disc Structure and Orientation in the Lensed and Microlensed
  Q0957+561 Quasar

abstract:
  Because quasars are unresolved in optical imaging, their structures must
presently be inferred. Gravitational microlensing offers the possibility to
produce information about the luminous structure provided the Einstein ring
diameter of the microlensing particle is comparable to or smaller than the
radiating quasar components. The long brightness history measured for the Q0957
quasar has been analyzed previously for information about the microlensing
particles, and evidence for the existence of a cosmologically significant
population of planetary mass particles has been reported. The microlensing
results have also directly determined the sizes of the ultraviolet light
emitting surfaces in the quasar Autocorrelation analysis of the same brightness
record has produced evidence for complex structure in the quasar; if the quasar
suddenly brightens today, it is probable that it will brighten again after 129,
190, 540, and 620 days. We interpret these lags as the result of luminous
structure around the quasar, and in particular we interpret them in the context
of the Elvis (2000) model of the quasar's structure. We find that the
autocorrelation peaks imply that beyond the luminous inner edge of the
accretion disc, the biconic structures of the Elvis model must lie at a radial
distance of 2x10^17 cm from the black hole, and 2x10^16 cm above and below the
plane of the accretion disc. The quasar is apparently inclined 55 degrees to
the line of sight. A second possible solution with lower inclination and larger
structure is also indicated but statistically less probable.


title:
Upper Limits on the Extragalactic Background Light from the Gamma-Ray
  Spectra of Blazars

abstract:
  The direct measurement of the extragalactic background light (EBL) is
difficult at optical to infrared wavelengths because of the strong foreground
radiation originating in the Solar System. Very high energy (VHE, E$>$100 GeV)
gamma rays interact with EBL photons of these wavelengths through pair
production. In this work, the available VHE spectra from six blazars are used
to place upper limits on the EBL. These blazars have been detected over a range
of redshifts and a steepening of the spectral index is observed with increasing
source distance. This can be interpreted as absorption by the EBL. In general,
knowledge of the intrinsic source spectrum is necessary to determine the
density of the intervening EBL. Motivated by the observed spectral steepening
with redshift, upper limits on the EBL are derived by assuming that the
intrinsic spectra of the six blazars are $\propto E^{-1.8}$. Upper limits are
then placed on the EBL flux at discrete energies without assuming a specific
spectral shape for the EBL. This is an advantage over other methods since the
EBL spectrum is uncertain.


title:
The Proper Motion of the Magellanic Clouds: The UCAC2-Hipparcos
  Inconsistency

abstract:
  Using the USNO CCD Astrograph all-sky Catalog (UCAC2), we measure the mean
proper motion of the two Magellanic Clouds. Appropriately selected LMC
populations show a proper motion (<\mu RA>, <\mu DEC>) ~ (+0.84,+4.32) that is
significantly higher, in <\mu DEC>, than currently accepted Hipparcos-like
values, <\mu RA>, <\mu DEC> ~ (+1.94,-0.14). A higher <\mu RA> value is also
found for the SMC. Interestingly, the mean UCAC2 LMC proper motion agrees very
well with the only work in the literature (Anguita et al. 2000) pointing to an
unbound Magellanic Clouds-Milky Way interaction. Nonetheless, the implications
of the UCAC2 proper motion are hard to reconcile with our present day
understanding of the Clouds-Galaxy interaction unless one assumes a more
massive Milky Way. Consequently, although no sources of systematic error have
been identified, it is perhaps most likely that the UCAC2 catalog has an as yet
unidentified systematic error resulting in an inconsistency between UCAC2 and
Hipparcos based results for the Magellanic Clouds.


title:
Solutions for 10,000 Eclipsing Binaries in the Bulge Fields of OGLE II
  Using DEBiL

abstract:
  We have developed a fully-automated pipeline for systematically identifying
and analyzing eclipsing binaries within large datasets of light curves. The
pipeline is made up of multiple tiers which subject the light curves to
increasing levels of scrutiny. After each tier, light curves that did not
conform to a given criteria were filtered out of the pipeline, reducing the
load on the following, more computationally intensive tiers. As a central
component of the pipeline, we created the fully automated Detached Eclipsing
Binary Light curve fitter (DEBiL), which rapidly fits large numbers of light
curves to a simple model. Using the results of DEBiL, light curves of interest
can be flagged for follow-up analysis. As a test case, we analyzed the 218699
light curves within the bulge fields of the OGLE II survey and produced 10862
model fits. We point out a small number of extreme examples as well as
unexpected structure found in several of the population distributions. We
expect this approach to become increasingly important as light curve datasets
continue growing in both size and number.


title:
Self-regulated black hole accretion, the M-sigma relation, and the
  growth of bulges in galaxies

abstract:
  We argue that the velocity dispersions and masses of galactic bulges and
spheroids are byproducts of the feedback that regulates rapid black hole growth
in protogalaxies. We suggest that the feedback energy liberated by accretion
must pass through the accreting material, in an energy-conserving flux close-in
and a momentum-conserving flux further out. If the inflowing gas dominates the
gravitational potential outside the Bondi radius, feedback from
Eddington-limited accretion drives the density profile of the gas to that of a
singular isothermal sphere. We find that the velocity dispersion associated
with the isothermal potential, sigma, increases with time as the black hole
mass M grows, in such a way that M is proportional to sigma^4. The coefficient
of this proportionality depends on the radius at which the flow switches from
energy conserving to momentum conserving, and gives the observed M-sigma
relation if the transition occurs at ~100 Schwarzschild radii. We associate
this transition with radiative cooling and show that bremsstrahlung, strongly
boosted by inverse Compton scattering in a two-temperature (T_p >> T_e) plasma,
leads to a transition at the desired radius.
  According to this picture, bulge masses M_b are insensitive to the virial
masses of their dark matter haloes, but correlate linearly with black hole
mass. Our analytic model also explains the M_b-sigma (Faber-Jackson) relation
as a relic of black hole accretion. The model naturally explains why the
M-sigma relation has less scatter than either the M-M_b (Magorrian) or the
Faber-Jackson relation. It suggests that the M-sigma relation could extend down
to very low velocity dispersions, and predicts that the relation should not
evolve with redshift.


title: High energy astrophysical processes

abstract:
  We briefly review the high energy astrophysical processes that are related to
the production of high energy $\gamma$-ray and neutrino signals and are likely
to be important for the energy loss of high and ultrahigh energy cosmic rays.
We also give examples for neutrino fluxes generated by different astrophysical
objects and describe the cosmological link provided by cosmogenic neutrinos.


title: The mass-metallicity relation for high-redshift damped Ly-alpha galaxies

abstract:
  We used our database of ESO VLT-UVES spectra of quasars to build up a sample
of 67 Damped Lyman-alpha (DLA) systems with redshifts 1.7<zabs<3.7. For each
system, we measured average metallicities relative to Solar, [X/H] (with either
X=Zn, S or Si), and the velocity widths of low-ionization line profiles, W1. We
find that there is a tight correlation between the two quantities, detected at
the 5sigma significance level. The existence of such a correlation, over more
than two orders of magnitude spread in metallicity, is likely to be the
consequence of an underlying mass-metallicity relation for the galaxies
responsible for DLA absorption lines. The best-fit linear relation is
[X/H]=1.35(\pm 0.11)\log W1 -3.69(\pm 0.18)$ with W1 expressed in km/s. While
the slope of this velocity-metallicity relation is the same within
uncertainties between the higher and the lower redshift bins of our sample,
there is a hint of an increase of the intercept point of the relation with
decreasing redshift. This suggests that galaxy halos of a given mass tend to
become more metal-rich with time. Moreover, the slope of this relation is
consistent with that of the luminosity-metallicity relation for local galaxies.
The DLA systems having the lowest metallicities among the DLA population would
therefore, on average, correspond to the galaxies having the lowest masses. In
turn, these galaxies should have the lowest luminosities among the DLA galaxy
population. This may explain the recent result that the few DLA systems with
detected Ly-alpha emission have higher than average metallicities.


title: INTEGRAL & RXTE Power Spectra of Cygnus X-1

abstract:
  We evaluate 0.03-20 Hz power spectra of the bright black hole binary Cyg X-1
obtained from non-deconvolved INTEGRAL-ISGRI event data. The ISGRI power
spectra are compared to contemporary RXTE-PCA ones in the same hard X-ray
energy band of 15-70 keV. They agree well in shape. Since the ISGRI power
spectrum of Cyg X-1 is not background corrected it lies about an order of
magnitude below the PCA values. In 2003 a soft outburst of Cyg X-1 occurred.
  From the RXTE-ASM and Ryle radio long term lightcurves and the RXTE spectra
we see a canonical ``hard state -- intermediate state -- soft state''
evolution. We discuss the evolution of the power spectra in the 15-70 keV range
which so far is much less well studied than that at softer energies. We
interpret our results regarding the origin of certain variability components.


title:
Model-Independent Multi-Variable Gamma-Ray Burst Luminosity Indicator
  and Its Possible Cosmological Implications

abstract:
  We present a multi-variable regression analysis to several observable
quantities for a sample of 15 gamma-ray bursts (GRBs). The observables used in
the analysis includes the isotropic gamma-ray energy (E_{gamma,iso}), the peak
energy of the nu F_nu spectrum in the rest frame (E_p'), and the rest frame
break time of the optical afterglow light curves(t_b'). A strong dependence of
E_{gamma, iso on E_p' and t_b' is derived. We also extend the analysis to the
isotropic afterglow energies in the X-ray and the optical bands, respectively,
and find that they are essentially not correlated with E_p' and t_b'. Regarding
the E_{gamma, iso(E_p', t_b') relationship as a luminosity indicator, we
explore the possible constraints on the cosmological parameters using the GRB
sample. Our results indicate 0.13<omega_M<0.49 and 0.50<Omega_Lambda<0.85 for a
flat Universe. The decelerating factor and its cosmological evolution, and the
transition redshift are also investigated. Through Monte Carlo simulations, we
find that the GRB sample satisfying our relationship observationally tends to
be a soft and bright one, and that the contraints on the cosmological
parameters can be much improved either by the enlargement of the sample size or
by the increase of the observational precision. Furthermore, the detections of
a few high redshift GRBs satisfying the correlation could greatly tighten the
constraints (abridged).


title:
The Geometry of and Mass Accretion Rate through the Maser Accretion Disk
  in NGC 4258

abstract:
  A maximum likelihood analysis of the NGC 4258 maser positions and velocities
reveals a ~2 sigma deviation from Keplerian motion in the projected rotation
curve of the high-velocity features, corresponding to a ~9 km/s, or 0.8%,
flattening of the LOS velocities with respect to Keplerian motion over the
range of the high-velocity masers. While there are a number of potential
explanations for this flattening, we argue for pure Keplerian rotation in an
inclination-warped disk based on the ability of this model to explain a number
of otherwise puzzling features of the system. A radial gradient in the disk
inclination of 0.034 mas^{-1} is not only consistent with the observed rotation
curve, but it generates a bowl along the near edge of the disk that naturally
explains the otherwise puzzling narrow spread in the declinations of the
systemic masers. It also explains the existence and location of an apparently
recurring flare amongst the systemic masers. There is no significant evidence
for non-Keplerian rotation in the inclination-warped disk. An additional
implication of the inclination warp is that the disk rises in front of and
obscures the central engine at a disk radius of about 8.3 mas, or 0.29 pc. By
comparing the observed X-ray column to conditions in the disk at this radius,
we argue that the molecular-to-atomic transition occurs just beyond the
outermost maser at 0.28 pc and from this we infer an accretion rate of
\~10^{-4}alpha M_sun/yr, consistent with the jet-dominated accretion models of
Yuan et al. (2002). Our model suggests that most of the observed X-ray column
arises in the warped accretion disk at 0.29 pc, and that the maser emission is
truncated at large radii predominantly as a result of the molecular-to-atomic
phase transition originally proposed by Neufeld & Maloney (1995).


title:
Deviation of light curves of gamma-ray burst pulses from standard forms
  due to the curvature effect of spherical fireballs or uniform jets

abstract:
  As revealed previously, under the assumption that some pulses of gamma-ray
bursts are produced by shocks in spherical fireballs or uniform jets of large
opening angles, there exists a standard decay form of the profile of pulses
arising from very narrow or suddenly dimming local (or intrinsic) pulses due to
the relativistic curvature effect (the Doppler effect over the spherical shell
surface). Profiles of pulses arising from other local pulses were previously
found to possess a reverse S-feature deviation from the standard decay form. We
show in this paper that, in addition to the standard decay form shown in Qin et
al. (2004), there exists a marginal decay curve associated with a local
$\delta$ function pulse with a mono-color radiation. We employ the sample of
Kocevski et al. (2003) to check this prediction and find that the phenomenon of
the reverse S-feature is common, when compared with both the standard decay
form and the marginal decay curve. We accordingly propose to take the marginal
decay curve (whose function is simple) as a criteria to check if an observed
pulse could be taken as a candidate suffered from the curvature effect. We
introduce two quantities $A_1$ and $A_2$ to describe the mentioned deviations
within and beyond the $FWHM$ position of the decay phase, respectively. The
values of $A_1$ and $A_2$ of pulses of the sample are calculated, and the
result suggests that for most of these pulses their corresponding local pulses
might contain a long decay time relative to the time scale of the curvature
effect.


title: GRAPE-6A: A single-card GRAPE-6 for parallel PC-GRAPE cluster system

abstract:
  In this paper, we describe the design and performance of GRAPE-6A, a
special-purpose computer for gravitational many-body simulations. It was
designed to be used with a PC cluster, in which each node has one GRAPE-6A.
Such configuration is particularly effective in running parallel tree
algorithm. Though the use of parallel tree algorithm was possible with the
original GRAPE-6 hardware, it was not very cost-effective since a single
GRAPE-6 board was still too fast and too expensive. Therefore, we designed
GRAPE-6A as a single PCI card to minimize the reproduction cost and optimize
the computing speed. The peak performance is 130 Gflops for one GRAPE-6A board
and 3.1 Tflops for our 24 node cluster. We describe the implementation of the
tree, TreePM and individual timestep algorithms on both a single GRAPE-6A
system and GRAPE-6A cluster. Using the tree algorithm on our 16-node GRAPE-6A
system, we can complete a collisionless simulation with 100 million particles
(8000 steps) within 10 days.


title: Determination of Cepheid parameters by light-curve template-fitting

abstract:
  We describe techniques to characterise the light-curves of regular variable
stars by applying principal component analysis (PCA) to a training set of high
quality data, and to fit the resulting light-curve templates to sparse and
noisy photometry to obtain parameters such as periods, mean magnitudes etc. The
PCA approach allows us to efficiently represent the multi-band light-curve
shapes of each variable, and hence quantitatively describe the average
behaviour of the sample as a smoothly varying function of period, and also the
range of variation around this average.
  In this paper we focus particularly on the utility of such methods for
analysing HST Cepheid photometry, and present simulations which illustrate the
advantages of our PCA template-fitting approach. These are: accurate parameter
determination, including light-curve shape information; simultaneous fitting to
multiple passbands; quantitative error analysis; objective rejection of
variables with non Cepheid-like light-curves or those with potential period
aliases.
  We also use PCA to confirm that Cepheid light-curve shapes are systematically
different (at the same period) between the Milky Way (MW) and the Large and
Small Magellanic Clouds (LMC, SMC), and consider whether light-curve shape
might therefore be used to estimate the mean metallicities of Cepheid samples,
thus allowing metallicity corrections to be applied to derived distance
estimates.


title: Simulating Gaia performances on white dwarfs

abstract:
  One of the most promising space missions of ESA is the astrometric satellite
Gaia, which will provide very precise astrometry and multicolour photometry,
for all 1.3 billion objects to V~20, and radial velocities with accuracies of a
few km/s for most stars brighter than V ~ 17. Consequently, full homogeneous
six-dimensional phase-space information for a huge number of stars will become
available. Our Monte Carlo simulator has been used to estimate the number of
white dwarfs potentially observable by Gaia. From this we assess which would be
the white dwarf luminosity functions which Gaia will obtain and discuss in
depth the scientific returns of Gaia in the specific field of white dwarf
populations. Scientific attainable goals include, among others, a reliable
determination of the age of the Galactic disk, a better knowledge of the halo
of the Milky Way and the reconstruction of the star formation history of the
Galactic disk. Our results also demonstrate the potential impact of a mission
like Gaia in the current understanding of the white dwarf cooling theory.


title: Dissipation in Pulsar Winds

abstract:
  I review the constraints placed on relativistic pulsar winds by comparing
optical and X-ray images of the inner Crab Nebula on the one hand with
two-dimensional MHD simulations on the other. The various proposals in the
literature for achieving the low magnetisation required at the inner edge of
the Nebula, are then discussed, emphasising that of dissipation in the
striped-wind picture. The possibility of direct observation of the wind is
examined. Based on the predicted orientation of the polarisation vector, I
outline a new argument suggesting that the off-pulse component of the optical
emission of the Crab pulsar originates in the wind.


title: Differential rotation on the lower main sequence

abstract:
  We compute the differential rotation of main sequence stars of the spectral
types F, G, K, and M by solving the equation of motion and the equation of
convective heat transport in a mean-field formulation. For each spectral type
the rotation rate is varied to study the dependence of the surface shear on
this parameter. The resulting rotation patterns are all solar-type. The
horizontal shear turns out to depend strongly on the effective temperature and
only weakly on the rotation rate. The meridional flow depends more strongly on
the rotation rate and has different directions in the cases of very slow and
very fast rotation, respectively.


title: Warm-Dense Molecular Gas in the ISM of Starbursts, LIRGs and ULIRGs

abstract:
  The role of star formation in luminous and ultraluminous infrared galaxies is
a hotly debated issue: while it is clear that starbursts play a large role in
powering the IR luminosity in these galaxies, the relative importance of
possible enshrouded AGNs is unknown. It is therefore important to better
understand the role of star forming gas in contributing to the infrared
luminosity in IR-bright galaxies. The J=3 level of 12CO lies 33K above ground
and has a critical density of ~1.5 X 10^4 cm^-3. The 12CO(J=3-2) line serves as
an effective tracer for warm-dense molecular gas heated by active star
formation. Here we report on 12CO (J=3-2) observations of 17 starburst spirals,
LIRGs and ULIRGs which we obtained with the Heinrich Hertz Submillimeter
Telescope on Mt. Graham, Arizona.
  Our main results are the following: 1. We find a nearly linear relation
between the infrared luminosity and warm-dense molecular gas such that the
infrared luminosity increases as the warm-dense molecular gas to the power
0.92; We interpret this to be roughly consistent with the recent results of Gao
& Solomon (2004a,b). 2. We find L_IR/M_H2 ratios ranging from ~10 to ~128
L_sun/M_sun using a standard CO-H2 conversion factor of 3 X 10^20 cm^-2 (K km
s^-1)^-1. If this conversion factor is ~an order of magnitude less, as
suggested in a recent statistical survey (Yao et al. 2003), then 2-3 of our
objects may have significant contributions to the L_IR by dust-enshrouded AGNs.


title: HII and H2 in the envelopes of cooling flow central galaxies

abstract:
  We report observations of ionized and warm molecular gas in the extended
regions of the central galaxies in several cooling flow clusters. These show
that both gas phases are present in these clusters to large radii. We trace
both Pa alpha and H2 lines to radii in excess of 20 kpc. The surface brightness
profiles of the two phases trace each other closely. Apart from very close to
the central AGN, line ratios in and between the phases vary only slowly with
position. The kinematics of the phases are indistinguishable and away from the
influence of the central AGN both the mean and dispersion in velocity are low
(<= 100 km/s) ruling out kinematic support of the molecular gas. All of the
above indicates that the mechanisms for heating the molecular gas and ionizing
the HII regions are highly coupled. The highest surface brightness emission
within a few kpc of the central AGN is distinct, both kinematically and
thermally from that at larger radii. The relative strengths of the Pa alpha to
the H2 lines indicates a source of UV excitation rich in EUV relative to FUV
photons, e.g. a black body with a temperature >= 10^5 K.


title: X-ray Light Curves and Accretion Disk Structure of EX Hydrae

abstract:
  We present X-ray light curves for the cataclysmic variable EX Hydrae obtained
with the Chandra High Energy Transmission Grating Spectrometer and the Extreme
Ultraviolet Explorer Deep Survey photometer. We confirm earlier results on the
shape and amplitude of the binary light curve and discuss a new feature: the
phase of the minimum in the binary light curve, associated with absorption by
the bulge on the accretion disk, increases with wavelength. We discuss several
scenarios that could account for this trend and conclude that, most likely, the
ionization state of the bulge gas is not constant, but rather decreases with
binary phase. We also conclude that photoionization of the bulge by radiation
originating from the white dwarf is not the main source of ionization, but that
it is heated by shocks originating from the interaction between the inflowing
material from the companion and the accretion disk. The findings in this paper
provide a strong test for accretion disk models in close binary systems.


title:
Measuring the halo mass of MgII absorbers from their cross-correlation
  with Luminous Red Galaxies

abstract:
  We study the cross-correlation between 716 MgII quasar absorption systems and
about 100,000 Luminous Red Galaxies (LRGs) selected from the Sloan Digital Sky
Survey Data Release 3 in the redshift range 0.4<z<0.8. The MgII systems were
selected to have 2796 & 2803 rest-frame equivalent widths greater than 1.0 \AA
and identifications confirmed by the FeII 2600 or MgI 2852 lines. Over
co-moving scales 0.2--13/h Mpc, the MgII--LRG cross-correlation has an
amplitude 0.69+/-0.09 times that of the LRG--LRG auto-correlation. Since LRGs
have halo-masses of 10^{13} \msun, this strong cross-correlation implies that
the absorber host-galaxies have halo-masses 1--2 times 10^{12} \msun.


title:
Remarks on the formulation of the cosmological constant/dark energy
  problems

abstract:
  Associated with the cosmic acceleration are the old and new cosmological
constant problems, recently put into the more general context of the dark
energy problem. In broad terms, the old problem is related to an unexpected
order of magnitude of this component while the new problem is related to this
magnitude being of the same order of the matter energy density during the
present epoch of cosmic evolution. Current plans to measure the equation of
state certainly constitute an important approach; however, as we discuss, this
approach is faced with serious feasibility challenges and is limited in the
type of conclusive answers it could provide. Therefore, is it really too early
to seek actively for new tests and approaches to these problems? In view of the
difficulty of this endeavor, we argue here that a good place to start is by
questioning some of the assumptions underlying the formulation of these
problems and finding new ways to put this questioning to the test. First, we
calculate how much fine tuning the cosmic coincidence problem represents. Next,
we discuss the potential of some cosmological probes such as gravitational
lensing to identify novel tests to probe dark energy questions and assumptions.
Then, motivated by some theorems in General Relativity, we discuss if the full
identification of the cosmological constant with vacuum energy is
unquestionable. Also, we point out the relevance of experiments at the
interface of astrophysics and quantum field theory, such as the Casimir effect
in gravitational and cosmological contexts. We conclude that challenging some
of the assumptions underlying the cosmological constant problems and putting
them to the test may prove useful and necessary to make progress on these
questions. (Abridged)


title: The Luminosity Function and Formation Rate History of GRBs

abstract:
  The isotropic luminosity function (LF) and formation rate history (FRH) of
long GRBs is by the first time constrained by using jointly both the observed
GRB peak-flux and redshift distributions. Our results support an evolving LF
and a FRH that keeps increasing after z=2. We discuss some interesting
implications related to these results.


title: Constraints on the Variation of G from Primordial Nucleosynthesis

abstract:
  We study here the effect of a varying G on the evolution of the early
Universe and, in particular, on primordial nucleosynthesis. This variation of G
is modelled using the Brans-Dicke theory as well as a more general class of
scalar-tensor theories. Modified nucleosynthesis codes are used to investigate
this effect and the results obtained are used to constrain the parameters of
the theories. We extend previous studies of primordial nucleosynthesis in
scalar-tensor theories by including effects which can cause a slow variation of
G during radiation domination and by including a late-time accelerating phase
to the Universe's history. We include a brief discussion on the epoch of
matter-radiation equality in Brans-Dicke theory, which is also of interest for
determining the positions of the cosmic microwave background power-spectrum
peaks.


title: Lyman Alpha Flux Power Spectrum and Its Covariance

abstract:
  We analyze the flux power spectrum and its covariance using simulated Lyman
alpha forests. We find that pseudo-hydro techniques are good approximations of
hydrodynamical simulations at high redshift. However, the pseudo-hydro
techniques fail at low redshift because they are insufficient for
characterizing some components of the low-redshift intergalactic medium,
notably the warm-hot intergalactic medium. Hence, to use the low-redshift Lyman
alpha flux power spectrum to constrain cosmology, one would need realistic
hydrodynamical simulations. By comparing one-dimensional mass statistics with
flux statistics, we show that the nonlinear transform between density and flux
quenches the fluctuations so that the flux power spectrum is much less
sensitive to cosmological parameters than the one-dimensional mass power
spectrum. The covariance of the flux power spectrum is nearly Gaussian. As
such, the uncertainties of the underlying mass power spectrum could still be
large, even though the flux power spectrum can be precisely determined from a
small number of lines of sight.


title: The cool wake around 4C 34.16 as seen by XMM-Newton

abstract:
  We present XMM-Newton observations of the wake-radiogalaxy system 4C34.16,
which shows a cool and dense wake trailing behind 4C34.16's host galaxy. A
comparison with numerical simulations is enlightening, as they demonstrate that
the wake is produced mainly by ram pressure stripping during the galactic
motion though the surrounding cluster. The mass of the wake is a substantial
fraction of the mass of an elliptical galaxy's X-ray halo. This observational
fact supports a wake formation scenario similar to the one demonstrated
numerically by Acreman et al (2003): the host galaxy of 4C34.16 has fallen into
its cluster, and is currently crossing its central regions. A substantial
fraction of its X-ray halo has been stripped by ram pressure, and remains
behind to form the galaxy wake.


title: Effects of Inhomogeneities on Cosmic Expansion

abstract:
  We evaluate the effect of inhomogeneity energy on the expansion rate of the
universe. Our method is to expand to Newtonian order in potential and velocity
but to take into account fully nonlinear density inhomogeneities. To linear
order in density, kinetic and gravitational potential energy contribute to the
total energy of the universe with the same scaling with expansion factor as
spatial curvature. In the strongly nonlinear regime, growth saturates, and the
net effect of the inhomogeneity energy on the expansion rate remains negligible
at all times. In particular, inhomogeneity contributions never mimic the
effects of dark energy or induce an accelerated expansion.


title: Dark Matter Dynamics and Indirect Detection

abstract:
  Non-baryonic, or "dark," matter is believed to be a major component of the
total mass budget of the universe. We review the candidates for particle dark
matter and discuss the prospects for direct detection (via interaction of dark
matter particles with laboratory detectors) and indirect detection (via
observations of the products of dark matter self-annihilations), focusing in
particular on the Galactic center, which is among the most promising targets
for indirect detection studies. The gravitational potential at the Galactic
center is dominated by stars and by the supermassive black hole, and the dark
matter distribution is expected to evolve on sub-parsec scales due to
interaction with these components. We discuss the dominant interaction
mechanisms and show how they can be used to rule out certain extreme models for
the dark matter distribution, thus increasing the information that can be
gleaned from indirect detection searches.


title: The Detection of Silicate Emission from Quasars at 10 and 18 Microns

abstract:
  We report the spectroscopic detection of silicate emission at 10 and 18
microns in five PG quasars, the first detection of these two features in
galaxies outside the Local Group. This finding is consistent with the
unification model for Active Galactic Nuclei (AGNs), which predicts that an AGN
torus seen pole-on should show a silicate emission feature in the mid-infrared.
The strengths of the detected silicate emission features range from 0.12 to
1.25 times the continuum at 10 microns and from 0.20 to 0.79 times the
continuum at 18 microns. The silicate grain temperatures inferred from the
ratio of 18-to-10 micron silicate features under the assumption of optically
thin emission range from 140 to 220K.


title:
A Deep Look at the T-Type Brown Dwarf Binary $\epsilon$ Indi Bab with
  Chandra and ATCA

abstract:
  We present deep observations of the nearby T-type brown dwarf binary
$\epsilon$ Indi Bab in radio with the Australia Telescope Compact Array and in
X-rays with the Chandra X-ray Observatory. Despite long integration times, the
binary (composed of T1 and T6 dwarfs) was not detected in either wavelength
regime. We reached $3\sigma$ upper limits of $1.23 \times 10^{12}$ and $1.74
\times 10^{12}$ erg/s/Hz for the radio luminosity at 4.8 GHz and 8.64 GHz,
respectively; in the X-rays, the upper limit in the $0.1-10$ keV band was $3.16
\times 10^{23}$ erg/s. We discuss the above results in the framework of
magnetic activity in ultracool, low-mass dwarfs.


title: Reply to Lyutikov's comments on Zhang & Kobayashi (2005)

abstract:
  Lyutikov (astro-ph/0503505) raised a valid point that for shock deceleration
of a highly magnetized outflow, the fate of the magnetic fields after shock
crossing should be considered. However, his comment that the deceleration
radius should be defined by the total energy rather than by the baryonic
kinetic energy is incorrect. As strictly derived from the shock jump conditions
in Zhang & Kobayashi (2005), during the reverse shock crossing process the
magnetic energy is not tapped. As a result, the fireball deceleration radius is
defined by the baryonic energy only. The magnetic energy is expected to be
transferred to the circumburst medium after the reverse shock disappears. The
evolution of the system then mimicks a continuously-fed fireball. As a result,
Lyutikov's naive conclusion that the forward shock dynamics is independent on
the ejecta content is also incorrect. The shock deceleration dynamics and the
reverse shock calculation presented in Zhang & Kobayashi (2005) are robust and
correct.


title:
A Mid-Infrared Imaging Survey of Embedded Young Stellar Objects in the
  Rho Ophiuchi Cloud Core

abstract:
  Results of a comprehensive, new, ground-based mid-infrared imaging survey of
the young stellar population of the Rho Ophiuchi cloud are presented. Data were
acquired at the Palomar 5-m and at the Keck 10-m telescopes with the MIRLIN and
LWS instruments, at 0.25 arcsec and 0.25 arcsec resolutions, respectively. Of
172 survey objects, 85 were detected. Among the 22 multiple systems observed,
15 were resolved and their individual component fluxes determined. A plot of
the frequency distribution of the detected objects with SED spectral slope
shows that YSOs spend ~400,000 yr in the Flat Spectrum phase, clearing out
their remnant infall envelopes. Mid-infrared variability is found among a
significant fraction of the surveyed objects, and is found to occur for all SED
classes with optically thick disks. Large-amplitude near-infrared variability,
also found for all SED classes with optically thick disks, seems to occur with
somewhat higher frequency at the earlier evolutionary stages. Although a
general trend of mid-infrared excess and NIR veiling exists proceeding through
SED classes, with Class I objects generally exhibiting K-veilings > 1, Flat
Spectrum objects with K-veilings > 0.58, and Class III objects with K-veilings
=0, Class II objects exhibit the widest range of K-band veiling values, 0-4.5.
However, the highly variable value of veiling that a single source can exhibit
in any of the SED classes in which active disk accretion can take place is
striking, and is direct observational evidence for highly time-variable
accretion activity in disks. Finally, by comparing mid-infrared vs.
near-infrared excesses in a subsample with well-determined effective
temperatures and extinction values, disk clearing mechanisms are explored. The
results are consistent with disk clearing proceeding from the inside-out.


title: Observational Tests of Intergalactic Enrichment Models

abstract:
  We summarize recent results assessing the carbon and silicon abundances of
the intergalactic medium (IGM) using the `pixel optical depth' technique. We
briefly discuss the implications of these results for models of intergalactic
enrichment, focusing on distinguishing `early' z >> 4 enrichment by the first
generations of stars and objects from `late' enrichment by 2 < z < 5 Ly-break
galaxies. We then discuss the comparison of observed QSO spectra to simulated
spectra generated from cosmological simulations that self-consistently include
enrichment, and draw qualitative implications for the general picture of
intergalactic enrichment at z > 2.


title:
Investigating Ca II emission in the RS CVn binary ER Vulpeculae using
  the Broadening Function Formalism

abstract:
  The synchronously rotating G stars in the detached, short-period (0.7 d),
partially eclipsing binary, ER Vul, are the most chromospherically active
solar-type stars known. We have monitored activity in the Ca II H & K reversals
for almost an entire orbit. Rucinski's Broadening Function Formalism allows the
photospheric contribution to be objectively subtracted from the highly blended
spectra. The power of the BF technique is also demonstrated by the good
agreement of radial velocities with those measured by others from less crowded
spectral regions. In addition to strong Ca II emission from the primary and
secondary, there appears to be a high-velocity stream flowing onto the
secondary where it stimulates a large active region on the surface 30 - 40
degrees in advance of the sub-binary longitude. A model light curve with a spot
centered on the same longitude also gives the best fit to the observed light
curve. A flare with approximately 13% more power than at other phases was
detected in one spectrum. We suggest ER Vul may offer a magnified view of the
more subtle chromospheric effects synchronized to planetary revolution seen in
certain `51 Peg'-type systems.


title: Magnetic flux captured by an accretion disk

abstract:
  We suggest a possible mechanism of efficient transport of the large-scale
external magnetic flux inward through a turbulent accretion disk. The outward
drift by turbulent diffusion which limits the effectiveness of this process is
reduced if the external flux passes through the disk in concentrated patches.
Angular momentum loss by a magnetocentrifugal wind from these patches of strong
field adds to the inward drift. We propose that magnetic flux accumulating in
this way at the center of the disk provides the `second parameter' determining
X-ray spectral states of black hole binaries, and the presence of relativistic
outflows.


title:
High-resolution radio imaging of the most distant radio quasar SDSS
  J0836+0054

abstract:
  We observed SDSS J0836+0054, the most distant radio-loud quasar known at
present (z=5.774) with the European Very Long Baseline Interferometry (VLBI)
Network at the 5 GHz frequency on 2003 November 4. The source is compact at the
milli-arcsecond (mas) angular scale with a flux density of 0.34 mJy. The
observations with the Very Large Array (VLA) made on the consecutive day
support a conclusion that the radio emission from SDSS J0836+0054 is
essentially confined within the central 40 pc. Based on our phase-referenced
VLBI observation, we obtained the astrometric position of the source accurate
to ~2 mas.


title:
Mid-infrared spectroscopy of two luminous submillimeter galaxies at
  z~2.8

abstract:
  Using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope,
we have obtained rest frame mid-infrared spectroscopy of two bright
submillimeter galaxies. SMMJ02399-0136 at z=2.81 shows a superposition of PAH
emission features and a mid-infrared continuum, indicating significant and
roughly equal contributions to its bolometric luminosity from star formation
and from a Compton-thick AGN. We derive a new redshift of z=2.80 for
MMJ154127+6616 from the IRS spectrum and find this object is dominated by
starburst PAH emission. The rest frame mid- to far-infrared spectral energy
distributions are consistent with these submillimeter galaxies being scaled up
versions of local ultraluminous infrared galaxies. The mid-infrared spectra
support the scenario that submillimeter galaxies are sites of extreme star
formation and represent a key phase in the formation of massive galaxies.


title: ISO observations and models of galaxies with Hidden Broad Line Regions

abstract:
  We present ISO mid-infrared spectrophotometry and far-infrared photometry of
galaxies with Hidden Broad Line Regions (HBLR). We also present radiative
transfer models of their spectral energy distributions which enable us to
separate the contributions from the dusty disc of the AGN and the dusty
starbursts. We find that the combination of tapered discs (discs whose
thickness increases with distance from the central source in the inner part but
stays constant in the outer part) and starbursts provide good fits to the data.
The tapered discs dominate in the mid-infrared part of the spectrum and the
starbursts in the far-infrared. After correcting the AGN luminosity for
anisotropic emission we find that the ratio of the AGN luminosity to the
starburst luminosity, L(AGN)/L(SB), ranges from about unity for IRAS14454-4343
to about 13 for IRAS01475-0740. Our results suggest that the warm IRAS colours
of HBLR are due to the relatively high L(AGN)/L(SB). Our fits are consistent
with the unified model and the idea that the infrared emission of AGN is
dominated by a dusty disc in the mid-infrared and starbursts in the
far-infrared.


title:
Abundances from disentangled component spectra: the eclipsing binary
  V578 Mon

abstract:
  Chemical abundances of the early-B type components of the binary V578 Mon are
derived from disentangled component spectra. This is a pilot study showing
that, even with moderately high line-broadening, metal abundances can be
derived from disentangled spectra with a precision 0.1 dex, relative to
sharp-lined single stars of the same spectral type. This binary is well-suited
for such an assessment because of its youth as a member of the Rosette Nebula
cluster NGC 2244, strengthening the expectation of an unevolved ZAMS chemical
composition. The method is of interest to study rotational driven mixing in
main-sequence stars, with fundamental stellar parameters known with higher
accuracy in (eclipsing) binaries. The paper also includes an evaluation of the
bias that might be present in disentangled spectra.


title:
Star Formation and Dust Attenuation Properties in Galaxies from a
  Statistical UV-to-FIR Analysis

abstract:
  We study two galaxy samples selected in ultraviolet (UV) and in far-infrared
(FIR) for which the spectral energy distributions (SEDs) from the far UV (FUV)
to the FIR are available. We compare the observed SEDs to modelled SEDs with
several star formation histories (SFHs; decaying star formation rate plus
burst) and attenuation laws (power law + 2175 Angstroem bump). The Bayesian
method allows to estimate statistically the best parameters by comparing each
observed SED to the full set of 82800 models. We reach the conclusion that the
UV dust attenuation cannot be estimated correctly from an SED analysis if the
FIR information is not used. The deduced dispersion is larger than with the FIR
data and the distribution is not symetrically distributed about zero: there is
an over-estimation for UV-selected galaxies and an under-estimation for
FIR-selected galaxies. The output from the analysis process suggests that
UV-selected galaxies have attenuation laws in average similar to the LMC
extinction while FIR-selected galaxy attenuation laws more resemble the MW
extinction law. The dispersion about the average relation in the
Log(Fdust/Ffuv) vs. FUV-NUV diagram (once the main relation with FUV-NUV is
accounted for) is explained by two other parameters: the slope of the
attenuation law and the instantaneous birthrate parameter b_0 for UV-selected
galaxies and the same ones plus the strength of the bump for the FIR-selected
galaxies. We propose a recipe to estimate the UV dust attenuation for
UV-galaxies only (that should be used whenever the FIR information is not
available because the resulting Afuv is poorly defined with an uncertainty of
about 0.32): A_{FUV} = 1.4168 (FUV-NUV)^2 + 0.3298 (NUV-I)^2 + 2.1207 (FUV-NUV)
+ 2.7465 (NUV-I) + 5.8408


title: Galactic Winds

abstract:
  Galactic winds are the primary mechanism by which energy and metals are
recycled in galaxies and are deposited into the intergalactic medium. New
observations are revealing the ubiquity of this process, particularly at high
redshift. We describe the physics behind these winds, discuss the observational
evidence for them in nearby star-forming and active galaxies and in the
high-redshift universe, and consider the implications of energetic winds for
the formation and evolution of galaxies and the intergalactic medium. To
inspire future research, we conclude with a set of observational and
theoretical challenges.


title: Evolution of reconnection along an arcade of magnetic loops

abstract:
  RHESSI observations of a solar flare showing continuous motions of double
hard X-ray sources interpreted as footpoints of magnetic loops are presented.
The temporal evolution shows many distinct emission peaks of duration of some
tens of seconds ('elementary flare bursts'). Elementary flare bursts have been
interpreted as instabilities or oscillations of the reconnection process
leading to an unsteady release of magnetic energy. These interpretations based
on two-dimensional concepts cannot explain these observations, showing that the
flare elements are displaced in a third dimension along the arcade. Therefore,
the observed flare elements are not a modulation of the reconnection process,
but originate as this process progresses along an arcade of magnetic loops.
Contrary to previous reports, we find no correlation between footpoint motion
and hard X-ray flux. This flare apparently contradicts the predictions of the
standard translation invariant 2.5D reconnection models.


title:
Constraints on the metagalactic hydrogen ionization rate from the
  Lyman-alpha forest opacity

abstract:
  Understanding the sources responsible for reionizing the Universe is a key
goal of observational cosmology. A discrepancy has existed between the
metagalactic hydrogen ionization rate, Gamma_HI, predicted by early
hydrodynamical simulations of the Lyman-alpha forest if scaled to appropriate
assumptions for the IGM temperature, when compared to values predicted from the
proximity effect. We present new estimates for Gamma_HI in the redshift range
2<z<4 based on hydrodynamical simulations of the Lyman-alpha forest opacity.
Within the current concordance cosmology, and assuming updated QSO emissivity
rates, a substantial contribution to the UV background from young star-forming
galaxies appears to be required over the entire redshift range. Our results are
consistent with lower-end estimates from the proximity effect. It is also found
that the errors on the ionization rate are dominated by uncertainties in the
thermal state of the intergalactic medium and the r.m.s fluctuation amplitude
at the Jeans scale.


title:
The 2dF QSO Redshift Survey - XV. Correlation analysis of redshift-Space
  distortions

abstract:
  We analyse the redshift-space (z-space) distortions of QSO clustering in the
2dF QSO Redshift Survey (2QZ). To interpret the z-space correlation function,
xi(sigma,pi), we require an accurate model for the QSO real-space correlation
function, xi(r). Although a single power-law xi(r) model fits the projected
correlation function (wp(sigma)) at small scales, it implies somewhat too
shallow a slope for both wp(sigma) and the z-space correlation function, xi(s),
at larger scales > 20 h^(-1) Mpc. Motivated by the form for xi(r) seen in the
2dF Galaxy Redshift Survey (2dFGRS) and in standard LCDM predictions, we use a
double power-law model for xi(r) which gives a good fit to xi(s) and wp(sigma).
The model is parametrized by a slope of gamma=1.45 for 1<r<10 h^(-1) Mpc and
gamma=2.30 for 10<r<40 h^(-1) Mpc. As found for 2dFGRS, the value of beta
determined from the ratio of xi(s)/xi(r) depends sensitively on the form of
xi(r) assumed. With our double power-law form for xi(r), we measure
beta(z=1.4)=0.32(+0.09)(-0.11). Assuming the same model for xi(r) we then
analyse the z-space distortions in the 2QZ xi(sigma,pi) and put constraints on
the values of Omega m and beta(z=1.4), using an improved version of the method
of Hoyle et al. The constraints we derive are Omega m=0.35(+0.19)(-0.13),
beta(z=1.4)=0.50(+0.13)(-0.15), in agreement with our xi(s)/\xi(r) results at
the ~1 sigma level.


title: The open cluster NGC 6520 and the nearby dark molecular cloud Barnard 86

abstract:
  Wide field BVI photometry and $^{12}$CO(1$\to$0) observations are presen ted
in the region of the open cluster NGC 6520 and the dark molecular cloud
Barnard~86. From the analysis of the optical data we find that the cluster is
rather compact, with a radius of 1.0$\pm$0.5 arcmin, smaller than previous
estimates. The cluster age is 150$\pm$50 Myr and the reddening
E$_{B-V}$=0.42$\pm$0.10. The distance from the Sun is estimated to be
1900$\pm$100 pc, and it is larger than previous estimates. We finally derive
basic properties of the dark nebula Barnard 86 on the assumption that it lies
at the same distance of the cluster.


title: On the Properties of the HI shells in the Small Magellanic CLoud

abstract:
  There are 509 expanding neutral hydrogen shells catalogued in the Small
Magellanic Cloud (SMC), all apparently very young, with dynamical ages of a few
Myr. To examine their relationship with young stellar objects we
cross-correlated the shell catalogue with various catalogues of OB
associations, super giants, Cepheids, WR stars, supernova remnants, and star
clusters. The incidence of chance line-ups was estimated via Monte-Carlo
simulations, and found to be high. However, it is important that there are 1.5
times more shells that are {\em not} spatially correlated to an OB association,
than shells that are. Moreover, 59 of the 509 shells lie mainly in low stellar
density fields and have no young stellar objects associated with them, and
therefore no obvious energy source. It is shown that, on the whole, the
properties of these "empty" shells are very similar to the properties of the
rest of the shells, once selection biases are taken into account. Theoretical
implications of the results are discussed.


title:
Instabilities, turbulence, and mixing in the ocean of accreting neutron
  stars

abstract:
  We consider the stability properties of the ocean of accreting magnetic
neutron stars. It turns out that the ocean is always unstable due to the
combined influence of the temperature and chemical composition gradients along
the surface and of the Hall effect. Both the oscillatory and non-oscillatory
modes can be unstable in accreting stars. The oscillatory instability grows on
a short timescale of the order os 0.1-10 s depending on the lengthscale of a
surface inhomogeneity and the wavelength of perturbations. The instability of
non-oscillatory modes is typically much slower and can develop on a timescale
of hours or days. Instability generates a weak turbulence that can be
responsible for mixing between the surface and deep ocean layers and for
spreading the accreted material over the stellar surface. Spectral features of
heavy elements can be detected in the atmospheres of accreting stars due to
mixing, and these features should be different in neutron stars with stable and
unstable burning. Motions caused by instability can also be the reason for slow
variations in the luminosity.


title: Fractal dimensions of the galaxy distribution varying by steps?

abstract:
  The structure of the large scale distribution of the galaxies have been
widely studied since the publication of the first catalogs. Since large
redshift samples are available, their analyses seem to show fractal
correlations up to the observational limits. The value of the fractal
dimension(s) calculated by different authors have become the object of a large
debate, as have been the value of the expected transition from fractality to a
possible large scale homogeneity. Moreover, some authors have proposed that
different scaling regimes might be discerned at different lenght scales. To go
further on into this issue, we have applied the correlation integral method to
the wider sample currently available. We therefore obtain a fractal dimension
of the galaxy distribution which seems to vary by steps whose width might be
related to the organization hierarchy observed for the galaxies. This result
could explain some of the previous results obtained by other authors from the
analyses of less complete catalogs and maybe reconcile their apparent
discrepancy. However, the method applied here needs to be further checked,
since it produces odd fluctuations at each transition scale, which need to be
thoroughly explained.


title: The HI Properties and Environment of Lyman-alpha Absorbers

abstract:
  We present results from two projects in which we have used the HI 21cm
emission line as a tracer of gas-rich galaxy populations in the vicinity of
Lyman-alpha absorbers. In the first case, we examine the HI environment of SBS
1543+593, the nearest damped Lyman-alpha absorber. We use a VLA map of the
region around this LSB galaxy which itself shows an extended HI disk to
identify 3 gas rich neighbors within 185 kpc. While it is not clear whether we
should expect local damped Lyman-alpha systems to reside in such gas-rich
regions, we would expect this kind of environment to be more prevalent at
higher redshifts where less of the gas is in the dense inner regions of
galaxies or has been consumed by star formation. This local galaxy is the only
system in which we can study the gaseous environment in this kind of detail. In
the second case, we examine the HI environment surrounding 16 Lyman-alpha
forest absorbers along 4 QSO sightlines. We do not detect any gas-rich galaxies
at the absorber positions indicating that, at least down to our sensitivity
limits, these absorption lines do not seem to be associated with galaxy halos.
For half of the Lyman-alpha absorption systems there is a galaxy within 500
kpc, but for the other half there is not. In two cases there is no galaxy
within 2 Mpc of the Lyman-alpha absorption systems indicating that absorbers
do, in some cases, reside in voids.


title: The pressure distribution in thermally bistable turbulent flows

abstract:
  We present a systematic numerical study of the effect of turbulent velocity
fluctuations on the thermal pressure distribution in thermally bistable flows.
The simulations employ a random turbulent driving generated in Fourier space
rather than star-like heating. The turbulent fluctuations are characterized by
their rms Mach number M and the energy injection wavenumber, k_for. Our results
are consistent with the picture that as either of these parameters is
increased, the local ratio of turbulent crossing time to cooling time
decreases, causing transient structures in which the effective behavior is
intermediate between the thermal-equilibrium and adiabatic regimes. As a
result, the effective polytropic exponent gamma_ef ranges between ~0.2 to ~1.1.
The fraction of high-density zones with P>10^4 Kcm^-3 increases from roughly
0.1% at k_for=2 and M=0.5 to roughly 70% for k_for=16 and M=1.25. A preliminary
comparison with the pressure measurements of Jenkins (2004) favors our case
with M=0.5 and k_for=2. In all cases, the dynamic range of the pressure summed
over the entire density range, typically spans 3-4 orders of magnitude. The
total pressure histogram widens as the Mach number is increased, and develops
near-power-law tails at high (resp.low) pressures when gamma_ef<~ 0.5 (resp.
gamma_ef>~ 1), which occurs at k_for=2 (resp.k_for=16) in our simulations. The
opposite side of the pressure histogram decays rapidly, in an approx. lognormal
form. Our results show that turbulent advection alone can generate large
pressure scatters, with power-law high-P tails for large-scale driving, and
provide validation for approaches attempting to derive the shape of the
pressure histogram through a change of variable from the known form of the
density histogram, such as that performed by MacLow et al.(2004).


title: Interstellar deuterated ammonia: From NH3 to ND3

abstract:
  We use spectra and maps of NH2D, ND2H, and ND3, obtained with the CSO, IRAM
30m and Arecibo telescopes, to study deuteration processes in dense cores. The
data include the first detection of the hyperfine structure of ND2H. The
emission of ND2H and ND3 does not seem to peak at the positions of the embedded
protostars, but instead at offset positions, where outflow interactions may
occur. A constant ammonia fractionation ratio in star-forming regions is
generally assumed to be consistent with an origin on dust grains. However, in
the pre-stellar cores studied here, the fractionation varies significantly when
going from NH3 to ND3. We present a steady state model of the gas-phase
chemistry for these sources, which includes passive depletion onto dust grains
and multiply saturated deuterated species up to five deuterium atoms (e.g.
CD5+). The observed column density ratios of all four ammonia isotopologues are
reproduced within a factor of 3 for a gas temperature of 10 K. We also predict
that deuterium fractionation remains significant at temperatures up to 20 K. ND
and NHD, which have rotational transitions in the submillimeter domain are
predicted to be abundant.


title: Evolution of the 0.01 - 25 Hz power spectral components in Cygnus X-1

abstract:
  Analyzing the archival data from the Rossi X-ray Timing Explorer (RXTE), we
study the power density spectra (PDS) of Cygnus X-1 from 1996 to 2003 in the
frequency range of 0.01 - 25 Hz. With our model we are able to track the
evolution of the Lorentzian components through all spectral states of the
source. We confirm the relation between characteristic frequencies seen both in
black hole candidate and neutron star sources, and show the changes in this
relation during the transitional and soft states of the source. The connection
between the Lorentzian components is investigated by analyzing similarities and
differences in their behavior. We find that the spectral state of the source
can be uniquely determined from the parameters of the these components. The
parameter correlations can all be described by continuous functions, which
differ between components. We discuss our results in the context of
relativistic precession model for the accretion disk, and show a remarkable
agreement between the model prediction and the data in the hard state. We
estimate a value for the specific angular momentum of a=+0.49 (-0.57) in the
case of prograde retrograde) rotation and an estimate for the inner radius of
22 to 50 (25 to 55) gravitational radii.


title:
Identification of Main Sequence Stars with Mid-Infrared Excesses Using
  GLIMPSE: Beta-Pictoris Analogs?

abstract:
  Spitzer IRAC 3.6-8 micron photometry obtained as part of the GLIMPSE survey
has revealed mid-infrared excesses for 33 field stars with known spectral types
in a 1.2 sq. degree field centered on the southern Galactic HII region RCW49.
These stars comprise a subset of 184 stars with known spectral classification,
most of which were pre-selected to have unusually red IR colors. We propose
that the mid-IR excesses are caused by circumstellar dust disks that are either
very late remnants of stellar formation or debris disks generated by planet
formation. Of these 33 stars, 29 appear to be main-sequence stars based on
optical spectral classifications. Five of the 29 main-sequence stars are O or B
stars with excesses that can be plausibly explained by thermal bremsstrahlung
emission, and four are post main-sequence stars. The lone O star is an O4V((f))
at a spectrophotometric distance of 3233+ 540- 535 pc and may be the earliest
member of the Westerlund 2 cluster. Of the remaining 24 main-sequence stars, 18
have SEDs that are consistent with hot dusty debris disks, a possible signature
of planet formation. Modeling the excesses as blackbodies demonstrates that the
blackbody components have fractional bolometric disk-to-star luminosity ratios,
LIR/L*, ranging from 10^-3 to 10^-2 with temperatures ranging from 220 to 820
K. The inferred temperatures are more consistent with asteroid belts rather
than the cooler temperatures expected for Kuiper belts. Mid-IR excesses are
found in all spectral types from late B to early K.


title:
CMB maps lensed by cosmological structures: Simulations and statistical
  analysis

abstract:
  A method for ray-tracing through n-body simulations has been recently
proposed. It is based on a periodic universe covered by simulation boxes.
Photons move along appropriate directions to avoid periodicity effects. Here,
an improved version of this method is applied to simulate lensed CMB maps and
maps of lens deformations. Particle mesh n-body simulations with appropriate
boxes and resolutions are used to evolve the nonlinear inhomogeneities until
present time. The resulting maps are statistically analyzed to look for
deviations from Gaussianity. These deviations are measured --for the first
time-- using correlations for configurations of n directions (n being smaller
than 7). A wide range of angular scales are considered. Some interesting
prospects are outlined.


title: Spectroscopy with Multichannel Correlation Radiometers

abstract:
  Correlation radiometers make true differential measurements in power with
high accuracy and small systematic errors. This receiver architecture has been
used in radio astronomy for measurements of continuum radiation for over 50
years; this article examines spectroscopy over broad bandwidths using
correlation techniques. After general discussions of correlation and the choice
of hybrid phase, experimental results from tests with a simple laboratory
multi-channel correlation radiometer are shown. Analysis of the effect of the
input hybrid's phase shows that a 90 degree hybrid is likely to be the best
general choice for radio astronomy, depending on its amplitude match and phase
flatness with frequency. The laboratory results verify that the combination of
the correlation architecture and an analog lag correlator is an excellent
method for spectroscopy over very wide bandwidths.


title: Is Thermal Emission in Gamma-Ray Bursts Ubiquitous?

abstract:
  The prompt emission of gamma-ray bursts has yet defied any simple
explanation, despite the presence of a rich observational material and great
theoretical efforts. Here we show that all the types of spectral evolution and
spectral shapes that have been observed can indeed be described with one and
the same model, namely a hybrid model of a thermal and a non-thermal component.
We further show that the thermal component is the key emission process
determining the spectral evolution. Even though bursts appear to have a variety
of, sometimes complex, spectral evolutions, the behaviors of the two separate
components are remarkably similar for all bursts, with the temperature
describing a broken power-law in time. The non-thermal component is consistent
with emission from a population of fast cooling electrons emitting
optically-thin synchrotron emission or non-thermal Compton radiation. This
indicates that these behaviors are the fundamental and characteristic ones for
gamma-ray bursts.


title: Kink Stability of Isothermal Spherical Self-Similar Flow Revisited

abstract:
  The problem of kink stability of isothermal spherical self-similar flow in
newtonian gravity is revisited. Using distribution theory we first develop a
general formula of perturbations, linear or non-linear, which consists of three
sets of differential equations, one in each side of the sonic line and the
other along it. By solving the equations along the sonic line we find
explicitly the spectrum, $k$, of the perturbations, whereby we obtain the
stability criterion for the self-similar solutions. When the solutions are
smoothly across the sonic line, our results reduce to those of Ori and Piran.
To show such obtained perturbations can be matched to the ones in the regions
outside the sonic line, we study the linear perturbations in the external
region of the sonic line (the ones in the internal region are identically
zero), by taking the solutions obtained along the line as the boundary
conditions. After properly imposing other boundary conditions at spatial
infinity, we are able to show that linear perturbations, satisfying all the
boundary conditions, exist and do not impose any additional conditions on $k$.
As a result, the complete treatment of perturbations in the whole spacetime
does not alter the spectrum obtained by considering the perturbations only
along the sonic line.


title: Ultrahigh Energy Activity in Giant Magnetar Outbursts

abstract:
  The recent superflare of 27 December 2004 from the magnetar SGR 1806-20 was
the brightest extrasolar flash ever recorded in the modern era. The chances for
seeing exotic ultrahigh energy (UHE) radiation - neutrons, neutrinos, gamma
rays and charged cosmic rays - from it are far better from an energetic point
of view than from cosmological gamma ray bursts (GRBs). The chances for
detecting the various components are discussed in light of recent data from the
27 December event.


title: Discovery of Strong Lensing by an Elliptical Galaxy at z=0.0345

abstract:
  We have discovered strong gravitational lensing by the galaxy ESO325-G004, in
images obtained with the Advanced Camera for Surveys on the Hubble Space
Telescope. The lens galaxy is a boxy group-dominant elliptical at z=0.0345,
making this the closest known galaxy-scale lensing system. The lensed object is
very blue (B-I = 1.1), and forms two prominent arcs and a less extended third
image. The Einstein radius is R_Ein=1.9 kpc (~3 arcsec on the sky, cf. 12
arcsec effective radius of the lens galaxy). Assuming a high redshift for the
source, the mass within R_Ein is 1.4x10^11 M_sun, and the I-band mass-to-light
ratio is 1.8 (M/L)_sun. The equivalent velocity dispersion is sigma_lens=310
km/s, in excellent agreement with the measured stellar dispersion sigma_v=320
km/s. Modeling the lensing potential with a singular isothermal ellipse (SIE),
we find close agreement with the light distribution. The best fit SIE model
reproduces the ellipticity of the lens galaxy to ~10%, and its position angle
within 1 degree. The model predicts the broad features of the arc geometry as
observed; the unlensed magnitude of the source is estimated at I ~ 23.75. We
suggest that one in ~200 similarly-massive galaxies within z<0.1 will exhibit
such a luminous multiply-imaged source.


title: Magnetic Fields in High-Density Stellar Matter

abstract:
  I briefly review some aspects of the effect of magnetic fields in the high
density regime relevant to neutron stars, focusing mainly on compact star
structure and composition, superconductivity, combustion processes, and gamma
ray bursts.


title: The Fall 2004 SDSS Supernova Survey

abstract:
  In preparation for the Supernova Survey of the Sloan Digital Sky Survey
(SDSS) II, a proposed 3-year extension to the SDSS, we have conducted an early
engineering and science run during the fall of 2004, which consisted of
approximately 20 scheduled nights of repeated imaging of half of the southern
equatorial stripe. Transient supernova-like events were detected in near
real-time and photometric measurements were made in the five SDSS filter
bandpasses with a cadence of ~2 days. Candidate type Ia supernovae (SNe) were
pre-selected based on their colors, light curve shape, and the properties of
the host galaxy. Follow-up spectroscopic observations were performed with the
Astrophysical Research Consortium 3.5m telescope and the 9.2m Hobby-Eberly
Telescope to confirm their types and measure the redshifts. The 2004 campaign
resulted in 22 spectroscopically confirmed SNe, which includes 16 type Ia, 5
type II, and 1 type Ib/c. These SN Ia will help fill in the sparsely sampled
redshift interval of z = 0.05 - 0.35, the so-called 'redshift desert', in the
Hubble diagram. Detailed investigation of the spectral properties of these
moderate-redshift SNe Ia will also provide a bridge between local SNe and
high-redshift objects, and will help us understand the systematics for future
cosmological applications that require high photometric precision. Finally, the
large survey volume also provides the opportunity to select unusual supernovae
for spectroscopic study that are poorly sampled in other surveys. We report on
some of the early results from this program and discuss potential future
applications.


title:
Constraints on the dark energy equation of state from the imprint of
  baryons on the power spectrum of clusters

abstract:
  Acoustic oscillations in the baryon-photon fluid leave a signature in the
matter power spectrum. The overall shape of the spectrum and the wavelength of
the oscillations depend upon the sound horizon scale at recombination. Using
the $\Lambda$ cold dark matter Hubble Volume simulation, we show that the
imprint of baryons is visible in the power spectrum of cluster-mass dark matter
haloes, in spite of significant differences between the halo power spectrum and
the prediction of linear perturbation theory. A measurement of the sound
horizon scale can constrain the dark energy equation of state. We show that a
survey of clusters at intermediate redshift ($ z\sim1 $), like the
Sunyaev-Zeldovich survey proposed by the South Pole Telescope or a red sequence
photometric survey with VISTA, could potentially constrain the sound horizon
scale to an accuracy of $\sim 2%$, in turn fixing the ratio of the pressure of
the dark energy to its density ($w$) to better than $\sim 10%$. Our approach
does not require knowledge of the cluster mass, unlike those that depend upon
the abundance of clusters.


title: 2dFGRS and SDSS Galaxy Group Density Profiles

abstract:
  We have analysed the distribution of galaxies in groups identified in the
largest redshift surveys at the present: the final release of the 2dF Galaxy
Redshift Survey and the first release of the Sloan Digital Sky Survey. Our work
comprises the study of the galaxy density profiles and the fraction of galaxies
per spectral type as a function of the group-centric distance. We have
calculated the projected galaxy density profiles of galaxy groups using
composite samples in order to increase the statistical significance of the
results. Special cares have been taken in order to avoid possible biases in the
group identification and the construction of the projected galaxy density
profile estimator. The results show that the projected galaxy density profiles
obtained for both redshift surveys are in agreement with a projected Navarro,
Frenk & White predictions in the range $0.15< r/r_{200}
  < 1$, whereas a good fit for the measured profiles in the whole range of
$r/r_{200}$ is given by a projected King profile. We have adopted a generalized
King profile to fit the measured projected density profiles per spectral type.
In order to infer the 3-D galaxy density profiles, we deproject the 2-D density
profiles using a deprojection method similar to the developed by Allen &
Fabian. From 2-D and 3-D galaxy density profiles we have estimated the
corresponding galaxy fractions per spectral type. The 2-D fraction of galaxies
computed using the projected profiles show a similar segregation of galaxy
spectral types as the obtained by Dom\'{\i}nguez et al. for groups in the early
data release of the 2dF Galaxy Redshift Survey. As expected, the trends
obtained for the 3-D galaxy fractions show steeper slopes than the observed in
the 2-D fractions.


title:
Detecting the stochastic gravitational wave background using pulsar
  timing

abstract:
  The direct detection of gravitational waves is a major goal of current
astrophysics. We provide details of a new method for detecting a stochastic
background of gravitational waves using pulsar timing data. Our results show
that regular timing observations of 40 pulsars each with a timing accuracy of
100 nano-seconds will be able to make a direct detection of the predicted
stochastic background from coalescing black holes within five years. With an
improved pre-whitening algorithm, or if the background is at the upper end of
the predicted range, a significant detection should be possible with only 20
pulsars.


title:
Diffuse light in z~0.25 galaxy clusters: constraining tidal damage and
  the faint end of the Luminosity Function

abstract:
  The starlight coming from the intergalactic space in galaxy clusters and
groups witnesses the violent tidal interactions that galaxies experience in
these dense environments. Such interactions may be (at least partly)
responsible for the transformation of normal star-forming galaxies into passive
dwarf ellipticals (dEs). In this contribution we present the first systematic
study of the IntraCluster Light (ICL) for a statistically representative sample
(Zibetti et al. 2005), which comprises 683 clusters selected between z=0.2 and
0.3 from ~1500 deg^2 in the SDSS. Their ICL is studied by stacking the images
in the g-, r-, and i-band after masking out all galaxies and polluting sources.
In this way a very uniform background illumination is obtained, that allows us
to measure surface brightnesses as faint as 31 mag/arcsec^2 and to trace the
ICL out to 700 kpc from the central galaxy. We find that the local fraction of
light contributed by intracluster stars rapidly decreases as a function of the
clustercentric distance, from ~40% at 100 kpc to ~5% at 500 kpc. By comparing
the distribution and colours of the ICL and of the clusters galaxies, we find
indication that the main source of ICL are the stars stripped from galaxies
that plunge deeply into the cluster potential well along radial orbits. Thus,
if dEs are the remnants of these stripped progenitors we should expect similar
radial orbital anisotropies and correlations between the dE luminosity function
and the amount of ICL in different clusters. The diffuse emission we measure is
contaminated by faint unresolved galaxies: this makes our flux estimate depend
to some extent on the assumed luminosity function, but, on the other hand,
allows us to constrain the number of faint galaxies. Our present results
disfavour steep (alpha<-1.35) faint-end powerlaw slopes.


title:
Cataclysmic variables from a ROSAT/2MASS selection I: Four new
  intermediate polars

abstract:
  We report the first results from a new search for cataclysmic variables (CVs)
using a combined X-ray (ROSAT) / infrared (2MASS) target selection that
discriminates against background AGN. Identification spectra were obtained at
the Isaac Newton Telescope for a total of 174 targets, leading to the discovery
of 12 new CVs. Initially devised to find short-period low-mass-transfer CVs,
this selection scheme has been very successful in identifying new intermediate
polars. Photometric and spectroscopic follow-up observations identify four of
the new CVs as intermediate polars: 1RXSJ063631.9+353537 (Porb~201min,
Pspin=1008.3408s or 930.5829), 1RXSJ070407.9+262501 (Porb~250min,
Pspin=480.708s), 1RXSJ173021.5-055933 (Porb=925.27min, Pspin=128.0s), and
1RXSJ180340.0+401214 (Porb=160.21min, Pspin=1520.51s). RXJ1730, also a
moderately bright hard X-ray source in the INTEGRAL/IBIS Galactic plane survey,
resembles the enigmatic AE Aqr. It is likely that its white dwarf is not
rotating at the spin equilibrium period, and the system may represent a
short-lived phase in CV evolution.


title:
NIR observations of dEs in the Virgo cluster: a structural continuity
  with giant Ellipticals

abstract:
  The structural properties of a sample of 50 dEs in the Virgo cluster are here
derived from Near InfraRed (NIR, H-band 1.65 micron) surface photometry and
analysed. One-dimensional surface brightness (SB) profiles are extracted using
elliptical isophote fitting. They are characterised by means of structural
parameters, namely the half light radius R_e, the average surface brightness
within R_e (mu_e), and a concentration index (c_31). We show that typical dEs
have close-to-exponential NIR SB distributions. The relations between dEs and
giant ellipticals (Es) are investigated by comparing the NIR structural
parameters of 273 Es in nearby clusters. Further analysis is conducted using
the optical-NIR colour B-H and by studying the relationships between structural
and dynamical parameters (fundamental plane) for the two classes of galaxies.
The transition between the two regimes is smooth and no dichotomy is seen.


title: CCD photometry of 23 minor planets

abstract:
  We present CCD photometric observations of 23 main-belt asteroids, of which 8
have never been observed before thus the data of these objects are the first in
the literature. The majority showed well detectable light variations, exceeding
0.1 mag. We have determined synodic periods for 756 Lilliana (9.36h), 1270
Datura (3.4h), 1400 Tirela (13.36h), 1503 Kuopio (9.98h), 3682 Welther (3.59h),
7505 Furushu (4.14h) and 11436 1969 QR (2.6h), while uncertain period estimates
were possible for 469 Argentina (12.3h), 546 Herodias (10.4h) and 1026 Ingrid
(5.3h). The shape of the lightcurves of 3682 Welther changed on a short
time-scale and showed dimmings that might be attributed to eclipses in a binary
system. For the remaining objects, only lower limits of the periods and
amplitudes were concluded.


title: Sulphur abundances in Terzan 7

abstract:
  We present here the first measurements of sulphur abundances in extragalactic
stars. We make use of high resolution spectra, obtained with UVES at the ESO
8.2 m Kueyen telescope, of three giants of the Globular Cluster Terzan 7, which
belongs to the Sagittarius dwarf galaxy. We measure the sulphur abundances
using the lines of S I multiplet 1. The S/Fe ratios for all three stars are
nearly solar, thus considerably lower than what is found in Galactic stars of
comparable iron content ([Fe/H] ~ -0.50). This finding is in keeping with the
abundances of other alpha-chain elements in this cluster and in Sagittarius and
other dSphs in general. These low alpha-chain elements to iron ratios suggest
that Sagittarius and its Globular Clusters have experienced a low or bursting
star-formation rate. Our sulphur abundances imply <\log (S/O)> = -1.61 which is
comparable to what is found in many H II regions of similar oxygen content, and
is slightly lower than the solar value (log (S/O)sun = -1.51). These are also
the first measurements of sulphur abundances in a Globular Cluster, thus a
direct comparison of Terzan 7 and Galactic Globular Clusters is not possible
yet. However our analysis suggests that the lines of S I multiplet 1 should be
measurable for other Globular Clusters at least down to a metallicity ~ -1.5.


title: Can the initial singularity be detected by cosmological tests?

abstract:
  In the present paper we raise the question whether initial cosmological
singularity can be proved from the cosmological tests. The classical general
relativity predict the existence of singularity in the past if only some energy
conditions are satisfied. On the other hand the latest quantum gravity
applications to cosmology suggest of possibility of avoiding the singularity
and replace it with the bounce. The distant type Ia supernovae data are used to
constraints on bouncing evolutional scenario where square of the Hubble
function $H^2$ is given by formulae
$H^2=H^2_0[\Omega_{m,0}(1+z)^{m}-\Omega_{n,0}(1+z)^{n}]$, where $\Omega_{m,0},
\Omega_{n,0}>0$ are density parameters and $n>m>0$. We show that the on the
base of the SNIa data standard bouncing models can be ruled out on the
$4\sigma$ confidence level. If we add the cosmological constant to the standard
bouncing model then we obtain as the best-fit that the parameter $\Omega_{n,0}$
is equal zero which means that the SNIa data do not support the bouncing term
in the model. The bounce term is statistically insignificant the present epoch.
We also demonstrate that BBN offer the possibility of obtaining stringent
constraints of the extra term $\Omega_{n,0}$. The other observational test
methods like CMB and the age of oldest objects in the Universe are used. We
also use the Akaike informative criterion to select a model according to the
goodness of fit and we conclude that this term should be ruled out by Occam's
razor, which makes that the big bang is favored rather then bouncing scenario.


title: Dark energy and the evolution of spherical overdensities

abstract:
  We use the non-linear spherical model in cold dark matter (CDM) cosmologies
with dark energy to investigate the effects of dark energy on the growth of
structure and the formation of virialised structures. We consider dark energy
models with a constant equation of state parameter w. For -1<w<-1/3, clusters
form earlier and are more concentrated in quintessence than in LambdaCDM
models, but they form later and are less concentrated than in the corresponding
open model with the same matter density and no dark energy. We point out some
confusion in the literature around the expression of the collapse factor (ratio
of the radius of the sphere at virialisation to that at turn-around) derived
from the virial theorem. We use the Sheth & Tormen extension of the
Press-Schechter framework to calculate the evolution of the cluster abundance
in different models and show the sensitivity of the cluster abundance to both
the amplitude of the mass fluctuations, sigma8, and the sigma8-w normalisation,
selected to match either the cosmic microwave background observations or the
abundance of X-ray clusters.


title:
Regularized orbit models unveiling the stellar structure and dark matter
  halo of the Coma elliptical NGC 4807

abstract:
  This is the second in a series of papers dedicated to unveil the mass
structure and orbital content of a sample of flattened early-type galaxies in
the Coma cluster. The ability of our orbit libraries to reconstruct internal
stellar motions and the mass composition of a typical elliptical in the sample
is investigated by means of Monte-Carlo simulations of isotropic rotator
models. The simulations allow a determination of the optimal amount of
regularization needed in the orbit superpositions. It is shown that under
realistic observational conditions and with the appropriate regularization
internal velocity moments can be reconstructed to an accuracy of about 15 per
cent; the same accuracy can be achieved for the circular velocity and dark
matter fraction. In contrast, the flattening of the halo remains unconstrained.
Regularized orbit superpositions are applied to a first galaxy in our sample,
NGC 4807, for which stellar kinematical observations extend to 3 Reff. The
galaxy seems dark matter dominated outside 2 Reff. Logarithmic dark matter
potentials are consistent with the data, as well as NFW-profiles, mimicking
logarithmic potentials over the observationally sampled radial range. In both
cases, the derived stellar mass-to-light ratio agrees well with independently
obtained mass-to-light ratios from stellar population analysis. Kinematically,
NGC 4807 is characterized by mild radial anisotropy outside r>0.5 Reff,
becoming isotropic towards the center. Our orbit models hint at either a
distinct stellar component or weak triaxiality in the outer parts of the
galaxy.


title:
Accounting for anisoplanatic point spread function in deep wide-field
  adaptive optics images

abstract:
  In this paper we present the approach we have used to determine and account
for the anisoplanatic point spread function (PSF) in deep adaptive optics (AO)
images for the Survey of a Wide Area with NACO (SWAN) at the ESO VLT. The
survey comprises adaptive optics observations in the Ks band totaling ~ 30
arcmin^2, assembled from 42 discrete fields centered on different bright stars
suitable for AO guiding. We develop a parametric model of the PSF variations
across the field of view in order to build an accurate model PSF for every
galaxy detected in each of the fields. We show that this approach is
particularly convenient, as it uses only easily available data and makes no
uncertain assumptions about the stability of the isoplanatic angle during any
given night. The model was tested using simulated galaxy profiles to check its
performance in terms of recovering the correct morphological parameters; we
find that the results are reliable up to Ks ~ 20.5 (K_AB ~ 22.3) in a typical
SWAN field. Finally, the model obtained was used to derive the first results
from five SWAN fields, and to obtain the AO morphology of 55 galaxies brighter
than Ks = 20. These preliminary results demonstrate the unique power of AO
observations to derive the details of faint galaxy morphologies and to study
galaxy evolution.


title: Testing the massive disk scenario for IRAS 18089-1732

abstract:
  Investigating in more detail the previously suggested massive disk scenario
for the High-Mass Protostellar Object IRAS18089-1732, we observed the source in
the 860mum band with the Submillimeter Array in various spectral lines and the
submm continuum emission at (sub-)arcsecond spatial resolution. Fifty spectral
lines from eighteen different species spanning upper level energy states
between 17 and 747K were detected. One of the assumed best tracers for massive
disks, CH3CN, is optically thick and does not allow a further disk
investigation. However, the complex molecule HCOOCH3 appears optically thin and
exhibits a velocity shift across the central core perpendicular to the
emanating outflow. Assuming equilibrium between centrifugal and gravitational
force, the estimated mass for this rotating structure is 16/(sin2(i))Msun (with
i the unknown inclination angle), of the same order as the gas mass derived
from the continuum emission. A temperature estimate based on the CH3CN(19--18)
K-ladder results in ~350K, thus a hot core has already formed in this region.
An analysis of the submm continuum emission reveals even at this high spatial
resolution only one isolated massive dust core without any detectable
companions down to mass limits between 0.2 and 3Msun (depending on the assumed
temperature). Potential implications for the massive cluster formation are
discussed.


title:
Evidence for Granulation and Oscillations in Procyon from Photometry
  with the WIRE satellite

abstract:
  We report evidence for the granulation signal in the star Procyon A, based on
two photometric time series from the star tracker on the WIRE satellite. The
power spectra show evidence of excess power around 1 milliHz, consistent with
the detection of p-modes reported from radial velocity measurements. We see a
significant increase in the noise level below 3 milliHz, which we interpret as
the granulation signal. We have made a large set of numerical simulations to
constrain the amplitude and timescale of the granulation signal and the
amplitude of the oscillations. We find that the timescale for granulation is
T(gran) = 750(200) s, the granulation amplitude is 1.8(0.3) times solar, and
the amplitude of the p-modes is 8(3) ppm. We found the distribution of peak
heights in the observed power spectra to be consistent with that expected from
p-mode oscillations. However, the quality of the data is not sufficient to
measure the large separation or detect a comb-like structure, as seen in the
p-modes of the Sun. Comparison with the recent negative result from the MOST
satellite reveal that the MOST data must have an additional noise source that
prevented the detection of oscillations.


title:
RR Lyrae variables in Galactic globular clusters V. The case of M3
  pulsators

abstract:
  We use our synthetic Horizontal Branch (HB) procedure to approach the debated
problem concerning the adequacy of canonical HB stellar models to account for
the observed peaked distribution of RR Lyrae fundamentalised periods in the
globular cluster M3. We find that by assuming a suitable bimodal mass
distribution, canonical models account for the observed period distribution. In
particular, the best fit model, out of nine random extractions, reaches a 99.9%
Kolmogorov-Smirnov (KS) probability. We also attempt a prediction of the
relative distribution of variables in fundamental and first overtone pulsators,
reaching a rather satisfactory agreement. However, one finds that canonical
models outnumber by roughly a factor of two the observed number of red HB
stars. Possible solutions for this discrepancy are outlined. Alternative
evolutionary scenarios are also briefly discussed.


title: Constraining Cosmological Parameters by the Cosmic Inversion Method

abstract:
  We investigate the question of how tightly we can constrain the cosmological
parameters by using the ``cosmic inversion'' method in which we directly
reconstruct the power spectrum of primordial curvature perturbations, $P(k)$,
from the temperature and polarization spectra of the cosmic microwave
background (CMB). In a previous paper, we suggested that it may be possible to
constrain the cosmological parameters using the fact that the reconstructed
$P(k)$ does not depend on how many polarization data we incorporate in our
inversion procedure if and only if the correct values of the cosmological
parameters are used. The advantage of this approach is that we need no
assumption regarding the functional form of $P(k)$. In this paper, we estimate
typical errors in the determination of the cosmological parameters when our
method is applied to the PLANCK observation. We investigate constraints on $h$,
$\Omega_b$, $\Omega_m$, and $\Omega_\Lambda$ through Monte Carlo simulations.


title:
X-ray reflection in the Seyfert galaxy 1H0419-577 revealing strong
  relativistic effects in the vicinity of a Kerr black hole

abstract:
  We report results obtained from six XMM-Newton observations of the Seyfert
galaxy 1H 0419-577. Here we show that the X-ray spectrum and variability are
well described by a two-component model comprising a power law with constant
spectral shape and variable normalisation and a much more constant ionised
reflection component from the inner accretion. One of the observations was
performed when the source was in a particularly low flux state in which the
X-ray spectrum is rather peculiar and exhibits a very flat hard spectrum with
broad residuals below 6.6 keV and a steep soft excess below about 1 keV. We
interpret the spectrum as being reflection-dominated by X-ray reprocessed
emission from the inner accretion disc. The primary continuum is almost
completely unobserved possibly because of strong light bending towards the
central black hole. The ionised reflection model simultaneously accounts for
the broad residuals and hard flat spectrum and for the soft excess. The same
model provides an excellent description of the data at all the other flux
levels, the most important difference being a variation in the power law
normalisation. Our results imply that most of the X-ray emission in this source
originates from within few gravitational radii from the central black hole and
requires that the compact object is an almost maximally spinning Kerr black
hole. (abridged)