title:
Kinematics of the Narrow-Line Region in the Seyfert 2 Galaxy NGC 1068:
  Dynamical Effects of the Radio Jet

abstract:
  We present a study of high-resolution long-slit spectra of the narrow-line
region (NLR) in NGC 1068 obtained with the Space Telescope Imaging Spectrograph
(STIS) aboard The Hubble Space Telescope (HST). The spectra were retrieved from
the Multimission Archive at Space Telescope (MAST) obtained from two visits and
seven orbits of HST time. We also obtained MERLIN radio maps of the center of
NGC 1068 to examine the dependence of the NLR cloud velocities on the radio
structure. The radial velocities and velocity dispersions of the bright NLR
clouds appear to be unaffected by the radio knots, indicating that the radio
jet is not the principal driving force on the outflowing NLR clouds. However,
the velocities of the fainter NLR clouds are split near knots in the jet,
indicating a possible interaction. Biconical outflow models were generated to
match the data and for comparison to previous models done with lower dispersion
observations. The general trend is an increase in radial velocity roughly
proportional to distance from the nucleus followed by a linear decrease after
roughly 100 parsec similar to that seen in other Seyfert galaxies, indicating
common acceleration/deceleration mechanisms.


title:
Resolving the pulsations of subdwarf B stars: PG 0154+182, HS 1824+5745,
  and HS 2151+0857

abstract:
  We continue our programme of extended single-site observations of pulsting
subdwarf B (sdB) stars and present the results of extensive time series
photometry to resolve the pulsation spectra for use in asteroseismological
analyses. PG 0154+182, HS 1824+5745, and HS 2151+0857 were observed at the MDM
Observatory during 2004 and 2005. Our observations are sufficient to resolve
the pulsations of all three target stars. We extend the number of known
frequencies for PG 0154+182 from one to six, confirm that HS 1824+5745 is a
mono-periodic pulsator, and extend the number of known frequencies to five for
HS 2151+0857. We perform standard tests to search for multiplet structure,
measure amplitude variations as pertains to stochastic excitation, and examine
the mode density to constrain the mode degree l.


title: HI Density Distribution Driven by Supernovae: A Simulation Study

abstract:
  We model the complex distribution of atomic hydrogen (HI) in the interstellar
medium (ISM) assuming that it is driven entirely by supernovae (SN). We develop
and assess two different models. In the first approach, the simulated volume is
randomly populated with non-overlapping voids of a range of sizes. This may
relate to a snapshot distribution of supernova-remnant voids, although somewhat
artificially constrained by the non-overlap criterion. In the second approach,
a simplified time evolution (considering momentum conservation as the only
governing constraint during interactions) is followed as SN populate the space
with the associated input mass and energy.
  We describe these simulations and present our results in the form of images
of the mass and velocity distributions and the associated power spectra. The
latter are compared with trends indicated by available observations. In both
approaches, we find remarkable correspondence with the observed statistical
description of well-studied components of the ISM, wherein the spatial spectra
have been found to show significant deviations from the Kolmogorov spectrum.
One of the key indications from this study, regardless of whether or not the
SN-induced turbulence is the dominant process in the ISM, is that the apparent
non-Kolmogorov spectral characteristics (of HI and/or electron column density
across thick or thin screens) needed to explain related observations may not at
all be in conflict with the underlying turbulence (i.e. the velocity structure)
being of Kolmogorov nature. We briefly discuss the limitations of our
simulations and the various implications of our results.


title:
The Host Galaxies of Narrow-Line Seyfert 1s: Nuclear Dust Morphology and
  Starburst Rings

abstract:
  We present a study of the nuclear morphology of a sample of narrow- and
broad-line Seyfert 1 galaxies (NLS1's and BLS1's) based on broad-band images in
the Hubble Space Telescope archives. In our previous study, we found that
large-scale stellar bars at > 1 kpc from the nucleus are more common in NLS1's
than BLS1's. In this paper we find that NLS1's preferentially have grand-design
dust spirals within approx. 1 kpc of their centers. We also find that NLS1's
have a higher fraction of nuclear star-forming rings than BLS1's. We find that
many of the morphological differences are due to the presence or absence of a
large-scale stellar bar within the spiral host galaxy. In general, barred
Seyfert 1s tend to have grand-design dust spirals at their centers, confirming
the results of other researchers. The high fraction of grand-design nuclear
dust spirals and stellar nuclear rings observed in NLS1's host galaxies
suggests a means for efficient fueling of their nuclei to support their high
Eddington ratios.


title: Self-Gravity Driven Instabilities in the ISM

abstract:
  In order to understand star formation it is important to understand the
dynamics of atomic and molecular clouds in the interstellar medium (ISM).
Nonlinear hydrodynamic flows are a key component to the ISM. One route by which
nonlinear flows arise is the onset and evolution of interfacial instabilities.
Interfacial instabilities act to modify the interface between gas components at
different densities and temperatures. Such an interface may be subject to a
host of instabilities, including the Rayleigh-Taylor, Kelvin-Helmholtz, and
Richtmyer-Meshkov instabilities. Recently, a new density interface instability
was identified. This self-gravity interfacial instability (SGI) causes any
displacement of the interface to gr ow on roughly a free-fall time scale, even
when the perturbation wavelength is much less than the Jeans length. In
previous work, we used numerical simulations to confirm the expectations of
linear theory and examine the nonlinear evolution of the SGI. We now continue
our study by generalizing our initial conditions to allow the acceleration due
to self-gravity to be non-zero across the interface. We also consider the
behaviour of the SGI for perturbation wavelengths near the Jeans wavelength. We
conclude that the action of self-gravity across a density interface may play a
significant role in the ISM either by fueling the growth of new instabilities
or modifying the evolution of existing instabilities.


title: A Search for Radio Emission from Type Ia Supernovae

abstract:
  We present and discuss the radio observations of 27 Type Ia supernovae (SNe
Ia) observed over two decades with the Very Large Array. No SN Ia has been
detected so far in the radio, implying a very low density for any possible
circumstellar material established by the progenitor, or progenitor system,
before explosion. We derive 2-sigma upper limits to a steady mass-loss rate for
individual SN systems as low as ~3 X 10^{-8} Msun yr^{-1}, discriminating
strongly against white dwarf accretion via a stellar wind from a massive binary
companion in the symbiotic star, an example of the ``single degenerate''
scenario. However, a white dwarf accreting from a relatively low mass companion
via a sufficiently high efficiency (>60-80%), Roche lobe overflow is still
consistent with our limits. The ``double degenerate'' merger scenario also
cannot be excluded.


title: Possible Detection of OVI from the LMC Superbubble N70

abstract:
  We present FUSE observations toward four stars in the LMC superbubble N70 and
compare these spectra to those of four comparison targets located in nearby
field and diffuse regions. The N70 sight lines show OVI 1032 absorption that is
consistently stronger than the comparison sight lines by ~60%. We attribute the
excess column density (logN_OVI=14.03 cm^-2) to hot gas within N70, potentially
the first detection of OVI associated with a superbubble. In a survey of 12 LMC
sight lines, Howk et al. (2002a) concluded that there was no correlation
between ISM morphology and N_OVI. We present a reanalysis of their measurements
combined with our own and find a clear difference between the superbubble and
field samples. The five superbubbles probed to date with FUSE show a
consistently higher mean N_OVI than the 12 non-superbubble sight lines, though
both samples show equivalent scatter from halo variability. Possible ionization
mechanisms for N70 are discussed, and we conclude that the observed OVI could
be the product of thermal conduction at the interface between the hot, X-ray
emitting gas inside the superbubble and the cooler, photoionized material
making up the shell seen prominently in Halpha. We calculate the total hydrogen
density n_H implied by our OVI measurements and find a value consistent with
expectations. Finally, we discuss emission-line observations of OVI from N70.


title:
Identifications of Four INTEGRAL Sources in the Galactic Plane via
  Chandra Localizations

abstract:
  Hard X-ray imaging of the Galactic plane by the INTEGRAL satellite is
uncovering large numbers of 20-100 keV "IGR" sources. We present results from
Chandra, INTEGRAL, optical, and IR observations of 4 IGR sources: 3 sources in
the Norma region of the Galaxy (IGR J16195-4945, IGR J16207-5129, and IGR
J16167-4957) and one that is closer to the Galactic center (IGR J17195-4100).
In all 4 cases, one relatively bright Chandra source is seen in the INTEGRAL
error circle, and these are likely to be the soft X-ray counterparts of the IGR
sources. They have hard 0.3-10 keV spectra with power-law photon indices of 0.5
to 1.1. While many previously studied IGR sources show high column densities,
only IGR J16195-4945 has a column density that could be as high as 10^23 cm^-2.
Using optical and IR sky survey catalogs and our own photometry, we have
obtained identifications for all 4 sources. The J-band magnitudes are in the
range 14.9-10.4, and we have used the optical/IR spectral energy distributions
(SEDs) to constrain the nature of the sources. Blackbody components with
temperature lower limits of >9400 K for IGR J16195-4945 and >18,000 K for IGR
J16207-5129 indicate that these are very likely High-Mass X-ray Binaries
(HMXBs). However, for IGR J16167-4957 and IGR J17195-4100, low extinction and
the SEDs indicate later spectral types for the putative companions, indicating
that these are not HMXBs.


title: Gravity, Dimension, Equilibrium, & Thermodynamics

abstract:
  Is it actually possible to interpret gravitation as space's property in a
pure classical way. Then, we note that extended self-gravitating system
equilibrium depends directly on the number of dimension of the space in which
it evolves. Given those precisions, we review the principal thermodynamical
knowledge in the context of classical gravity with arbitrary dimension of
space. Stability analyses for bounded 3D systems, namely the Antonov
instability paradigm, are then rapproched to some amazing properties of
globular clusters and galaxies.


title:
Dynamical Influences of the Last Magellanic Interaction On the
  Magellanic Clouds

abstract:
  We investigate the present distributions of gas and young stars in the Large
and Small Magellanic Clouds (LMC and SMC) based on fully self-consistent
numerical simulations of the Clouds for the last ~ 0.8 Gyr. Our principal
results, which can be tested against observations, are as follows. The last
dynamical and hydrodynamical interaction between the Clouds about ~ 0.2 Gyr ago
can form the apparently off-center bar and peculiar HI spirals of the LMC. The
present spatial distributions of young stars with ages less than 20 Myr in the
LMC can be significantly asymmetric and clumpy owing to the interaction. A
small but non-negligible fraction of stellar and gaseous components can be
transferred from the SMC into the LMC during the interaction to form diffuse
halo components around the LMC. The burst of star formation in the SMC can be
synchronized with that of the LMC about 0.2 Gyr ago in some models. New stars
can form from gas in the SMC's tidal tails, one of which can be observed as the
Magellanic Bridge (MB). The metallicity distribution function of new stars in
the MB has a peak of [Fe/H] ~ -0.8, which is significantly smaller than the
stellar metallicity of the SMC. Based on these results, we discuss the origin
of 30 Doradus, the southern molecular ridge of the LMC, the globular cluster
ESO 121-SC03, metal-poor inter-Cloud stars within the MB, and giant HI holes of
the LMC.


title: Evidence for Rapidly Spinning Black Holes in Quasars

abstract:
  It has long been believed that accretion onto supermassive black holes powers
quasars, but there has been relatively few observational constraints on the
spins of the black holes. We address this problem by estimating the average
radiative efficiencies of a large sample of quasars selected from the Sloan
Digital Sky Survey, by combining their luminosity function and their black hole
mass function. Over the redshift interval $0.4<z<2.1$, we find that quasars
have average radiative efficiencies of $\sim 30% - 35%$, strongly suggesting
that their black holes are rotating very fast, with specific angular momentum
$a \approx 1$, which stays roughly constant with redshift. The average
radiative efficiency could be reduced by a factor of $\sim$2, depending on the
adopted zeropoint for the black hole mass scale. The inferred large spins and
their lack of significant evolution are in agreement with the predictions of
recent semi-analytical models of hierarchical galaxy formation if black holes
gain most of their mass through accretion.


title: The high-mass star-forming region IRAS18182-1433

abstract:
  Submillimeter Array 1.3mm line and continuum observations toward the young
massive star-forming region IRAS18182-1433 are presented. The data are
complemented with short-spacing CO(2-1) observations and SiO(1-0) data from the
VLA. Multiple massive outflows emanate from the mm continuum peak. The CO(2-1)
data reveal a quadrupolar outflow system consisting of two outflows inclined by
\~90 degrees. One outflow exhibits a cone-like red-shifted morphology with a
jet-like blue-shifted counterpart where a blue counter-cone can only be
tentatively identified. The SiO(1-0) data suggest the presence of a third
outflow. Analyzing the 12CO/13CO line ratios indicates decreasing CO line
opacities with increasing velocities. The other seven detected molecular
species - also high-density tracers like CH3CN, CH3OH, HCOOCH3 - are all ~1-2''
offset from the mm continuum peak, but spatially associated with a strong
molecular outflow peak and a cm emission feature indicative of a thermal jet.
This spatial displacement between the molecular lines and the mm continuum
emission could be either due to an unresolved sub-source at the position of the
cm feature, or the outflow/jet itself alters the chemistry of the core
enhancing the molecular abundances toward that region. A temperature estimate
based on the CH3CN(12_k-11_k) lines suggests temperatures of the order 150K. A
velocity analysis of the high-density tracing molecules reveals that at the
given spatial resolution none of them shows any coherent velocity structure
which would be consistent with a rotating disk. We discuss this lack of
rotation signatures and attribute it to intrinsic difficulties to
observationally isolate massive accretion disks from the surrounding dense gas
envelopes and the molecular outflows.


title: Coronal emission from the shocked circumstellar ring of SN 1987A

abstract:
  High resolution spectra with UVES/VLT of SN 1987A from December 2000 until
November 2005 show a number of high ionization lines from gas with velocities
of roughly 350 km/s, emerging from the shocked gas formed by the ejecta-ring
collision. These include coronal lines from [Fe X], [Fe XI] and [Fe XIV] which
have increased by a factor of about 20 during the observed period. The
evolution of the lines is similar to that of the soft X-rays, indicating that
they arise in the same component. The line ratios are consistent with those
expected from radiative shocks with velocity 310-390 km/s, corresponding to a
shock temperature of (1.6-2.5) x 10^6 K. A fraction of the coronal emission
may, however, originate in higher velocity adiabatic shocks.


title: SNe feedback and the formation of elliptical galaxies

abstract:
  The processes governing both the formation and evolution of elliptical
galaxies are discussed by means of a new multi-zone photo-chemical evolution
model for elliptical galaxies, taking into account detailed nucleosynthetic
yields, feedback from supernovae, Pop III stars and an initial infall episode.
  By comparing model predictions with observations, we derive a picture of
galaxy formation in which the higher is the mass of the galaxy, the shorter are
the infall and the star formation timescales. In particular, by means of our
model, we are able to reproduce the overabundance of Mg relative to Fe,
observed in the nuclei of bright ellipticals, and its increase with galactic
mass.
  This is a clear sign of an anti-hierarchical formation process. Therefore, in
this scenario, the most massive objects are older than the less massive ones,
in the sense that larger galaxies stop forming stars at earlier times.
  Each galaxy is created outside-in, i.e. the outermost regions accrete gas,
form stars and develop a galactic wind very quickly, compared to the central
core in which the star formation can last up to ~1.3 Gyr. This finding will be
discussed at the light of recent observations of the galaxy NGC 4697 which
clearly show a strong radial gradient in the mean stellar [<Mg/Fe>] ratio.
  The role of galactic winds in the IGM/ICM enrichment will also be discussed.


title: Inhomogeneous Big Bang Nucleosynthesis Revisited

abstract:
  We reanalyze the allowed parameters for inhomogeneous big bang
nucleosynthesis in light of the WMAP constraints on the baryon-to-photon ratio
and a recent measurement which has set the neutron lifetime to be 878.5 +/- 0.7
+/- 0.3 seconds. For a set baryon-to-photon ratio the new lifetime reduces the
mass fraction of He4 by 0.0015 but does not significantly change the abundances
of other isotopes. This enlarges the region of concordance between He4 and
deuterium in the parameter space of the baryon-to-photon ratio and the IBBN
distance scale. The Li7 abundance can be brought into concordance with observed
He4 and deuterium abundances by using depletion factors as high as 9.3. The
WMAP constraints, however, severely limit the allowed comoving (T = 100 GK)
inhomogeneity distance scale to (1.3 - 2.6)x10^5 cm.


title: New signposts of massive star formation in the S235A-B region

abstract:
  We report on new aspects of the star-forming region S235AB revealed through
high-resolution observations at radio and mid-infrared wavelengths. Using the
Very Large Array, we carried out sensitive observations of S235AB in the cm
continuum (6, 3.6, 1.3, and 0.7) and in the 22 GHz water maser line. These were
complemented with Spitzer Space Telescope Infrared Array Camera archive data to
clarify the correspondence between radio and IR sources. We made also use of
newly presented data from the Medicina water maser patrol, started in 1987, to
study the variability of the water masers found in the region. S235A is a
classical HII region whose structure is now well resolved. To the south, no
radio continuum emission is detected either from the compact molecular core or
from the jet-like structure observed at 3.3 mm, suggesting emission from dust
in both cases. We find two new compact radio continuum sources (VLA-1 and
VLA-2) and three separate maser spots. VLA-1 coincides with one of the maser
spots and with a previously identified IR source (M1). VLA-2 lies towards S235B
and represents the first radio detection from this peculiar nebula that may
represent an ionized wind from a more evolved star. The two other maser spots
coincide with an elongated structure previously observed within the molecular
core in the C34S line. This structure is perpendicular to a bipolar molecular
outflow observed in HCO+(1-0) and may trace the associated equatorial disk. The
Spitzer images reveal a red object towards the molecular core. This is the most
viable candidate for the embedded source originating the outflow and maser
phenomenology. The picture emerging from these and previous data shows the
extreme complexity of a small (< 0.5 pc) star-forming region where widely
different stages of stellar evolution are present.


title:
Quasar Luminosity Functions from Joint Evolution of Black Holes and Host
  Galaxies

abstract:
  We show that our previously proposed anti-hierarchical baryon collapse
scenario for the joint evolution of black holes and host galaxies predicts
quasar luminosity functions at redshifts 1.5<z<6 and local properties in nice
agreement with observations. In our model the quasar activity marks and
originates the transition between an earlier phase of violent and heavily
dust-enshrouded starburst activity promoting rapid black hole growth, and a
later phase of almost passive evolution; the former is traced by the
submillimeter-selected sources, while the latter accounts for the high number
density of massive galaxies at substantial redshifts z>1.5, the population of
Extremely Red Objects, and the properties of local ellipticals.


title: The chemical evolution of the Milky Way: from light to heavy elements

abstract:
  We present results for the chemical evolution of the Milky Way including
predictions for elements from Deuterium to Europium. A comparison with the most
accurate and recent data allows us to draw important conclusions on stellar
nucleosynthesis processes as well as on mechanisms of galaxy formation.


title: GalICS V : Low and high order clustering in mock SDSS's

abstract:
  [Abridged] We use mock catalogues based on the GALICS model (Hatton et al.
03) to explore the nature of galaxy clustering observed in the SDSS. We measure
low and high order angular clustering statistic from these mock catalogues,
after selecting galaxies the same way as for observations, and compare them
directly to estimates from SDSS data. Note that we also present measurements of
S3-S5 on the SDSS DR1. We find that our model is in general good agreement with
observations in the scale/luminosity range where we can trust the predictions.
This range is found to be limited (i) by the size of the dark matter simulation
used -- which introduces finite volume effects at large scales -- and by the
mass resolution of this simulation -- which introduces incompleteness at
apparent magnitudes fainter than $r\sim 20$. We then focus on the small scale
clustering properties of galaxies and investigate the behaviour of three
different prescriptions for positioning galaxies within haloes of dark matter.
We show that galaxies are poor tracers both of DM particles or DM
sub-structures, within groups and clusters. Instead, SDSS data tells us that
the distribution of galaxies lies somewhat in between these two populations.
This confirms the general theoretical expectation from numerical simulations
and semi-analytic modelling.


title: Internal kinematics of modelled interacting disc galaxies

abstract:
  We present an investigation of galaxy-galaxy interactions and their effects
on the velocity fields of disc galaxies in combined N-body/hydrodynamic
simulations, which include cooling, star formation with feedback, and galactic
winds. Rotation curves (RCs) of the gas are extracted from these simulations in
a way that follows the procedure applied to observations of distant, small, and
faint galaxies as closely as possible. We show that galaxy-galaxy mergers and
fly-bys disturb the velocity fields significantly and hence the RCs of the
interacting galaxies, leading to asymmetries and distortions in the RCs.
Typical features of disturbed kinematics are significantly rising or falling
profiles in the direction of the companion galaxy and pronounced bumps in the
RCs. In addition, tidal tails can leave strong imprints on the rotation curve.
All these features are observable for intermediate redshift galaxies, on which
we focus our investigations. We use a quantitative measure for the asymmetry of
rotation curves to show that the appearance of these distortions strongly
depends on the viewing angle. We also find in this way that the velocity fields
settle back into relatively undisturbed equilibrium states after unequal mass
mergers and fly-bys. About 1 Gyr after the first encounter, the RCs show no
severe distortions anymore. These results are consistent with previous
theoretical and observational studies. As an illustration of our results, we
compare our simulated velocity fields and direct images with rotation curves
from VLT/FORS spectroscopy and ACS images of a cluster at z=0.53 and find
remarkable similarities.


title: Unveiling obscured accretion

abstract:
  We present the latest determination of the X-ray (2-10 keV) AGN luminosity
function accounting for the selection effect due to X-ray absorption. The main
results are: 1) the inclusion of obscured AGN confirms the AGN differential
luminosity evolution, but makes it less extreme than what is found selecting
unobscured AGN in soft X-rays, and more similar to a pure luminosity evolution;
2) significant correlations are found between the fraction of obscured sources,
the luminosity and the redshift, this fraction increasing toward both low AGN
luminosities and high redshifts. We discuss our findings in a scenario for the
formation and evolution of the structure in the Universe where the bulk of
nuclear activity is produced at z=1-2. At the same redshifts also the
star-formation rate reaches a maximum, and this age can therefore be regarded
as the "golden age" for nuclear and galaxy activity. We discuss the current
observational limits of this program and the improvements needed to obtain an
unbiased census of the AGN and super-massive black hole (SMBH) population.


title:
Avoiding the Big-Rip Jeopardy in a Quintom Dark Energy Model with Higher
  Derivatives

abstract:
  In the framework of a single scalar field quintom model with higher
derivative, we construct in this paper a dark energy model of which the
equation of state (EOS) $w$ crosses over the cosmological constant boundary.
Interestingly during the evolution of the universe $w<-1$ happens just for a
period of time with a distinguished feature that $w$ starts with a value above
-1, transits into $w<-1$, then comes back to $w>-1$. This avoids the Big Rip
jeopardy induced by $w<-1$.


title: The velocity dispersion and mass profile of the Milky Way

abstract:
  We re-analyse the velocity-dispersion profile sigma(r) at radii r>10 kpc in
the Galactic stellar halo, recently derived by Battaglia et al. (2005), who
concluded that, for constant velocity anisotropy of the tracers, these data
rule out a flat circular-speed curve for the Milky Way. However, we demonstrate
that if one makes the natural assumption that the tracer density is truncated
at r_t >~ 160 kpc and falls off significantly more steeply than r^-3.5 at r >~
80 kpc, then these data are consistent with a flat circular-speed curve and a
constant velocity anisotropy comparable to that observed for halo stars in the
Solar neighbourhood. We also consider a more detailed mass model with an
exponential stellar disc and an extended non-isothermal dark-matter halo. In
this two-component model, the Milky Way's virial radius and mass are r_vir =
200 kpc and M_vir = 1.5 x 10^12 M_sun. Still assuming the tracers' velocity
anisotropy to be constant (at beta=0.5) we again find good agreement with the
observed sigma(r), so long as the tracer density is truncated near the virial
radius. These data by themselves do not allow to differentiate between
different dark-halo or total-mass models for the Milky Way, nor between
different velocity-anisotropy profiles for the tracers.


title:
Witnessing galaxy preprocessing in the local Universe: the case of a
  star-bursting group falling into Abell 1367

abstract:
  We present a multiwavelength analysis of a compact group of galaxies
infalling at high speed into the dynamically young cluster Abell 1367. Peculiar
morphologies and unusually high Halpha emission are associated with two giant
galaxies and at least ten dwarfs/extragalactic HII regions, making this group
the region with the highest density of star formation activity ever observed in
the local clusters. Moreover Halpha imaging observations reveal extraordinary
complex trails of ionized gas behind the galaxies, with projected lengths
exceeding 150 kpc. These unique cometary trails mark the gaseous trajectory of
galaxies, witnessing their dive into the hot cluster intergalactic medium.
Under the combined action of tidal forces among group members and the
ram-pressure by the cluster ambient medium, the group galaxies were fragmented
and the ionized gas was blown out. The properties of this group suggest that
environmental effects within infalling groups may have represented a
preprocessing step of the galaxy evolution during the high redshift cluster
assembly phase.


title: AGN Outflows in Emission and Absorption: The SDSS Perspective

abstract:
  A variety of investigations have demonstrated commonalities between the
Baldwin (1977) Effect, the blueshifting of CIV emission lines (e.g., Gaskell
1982; Richards et al. 2002), and the L_UV-L_X relationship (e.g., Avni &
Tananbaum 1982; Strateva et al. 2005; Steffen et al. 2006); indeed all three of
these observational effects may be manifestations of the same underlying (but
still uncertain) physics. This commonality is of interest to investigations of
accretion disk winds (e.g., Murray et al. 1995; Proga et al. 2000) from active
galactic nuclei (AGN) as there is evidence that broad absorption line quasars
(BALQSOs) are drawn from a parent sample of quasars that exhibit larger than
average CIV blueshifts, weaker than average CIV emission line strengths, and
bluer than average (intrinsic) colors. The properties of the absorption troughs
appear to be dependent upon these parameters. Thus, it is suggested that not
all quasars will host bona-fide BAL troughs, but that all (broad emission line)
quasars host outflows of some type, the structure of which is strongly
dependent on the quasar's spectral energy distribution.


title: The interaction of gravitational waves with strongly magnetized plasmas

abstract:
  We study the interaction of a gravitational wave (GW) with a plasma that is
strongly magnetized. The GW is considered a small disturbance, and the plasma
is modeled by the general relativistic analogue of the induction equation of
ideal MHD and the single fluid equations. The equations are derived without
neglecting any of the non-linear interaction terms, and the non-linear
equations are integrated numerically. We find that for strong magnetic fields
of the order of $10^{15} $G the GW excites electromagnetic plasma waves very
close to the magnetosonic mode. The magnetic and electric field oscillations
have very high amplitude, and a large amount of energy is absorbed from the GW
by the electromagnetic oscillations, of the order of $10^{23} $erg/cm$^3$ in
the case presented here. The absorbed energy is proportional to $B_0^2$, with
$B_0$ the background magnetic field. The energization of the plasma takes place
on fast time scales of the order of milliseconds. The amount of absorbed energy
is comparable to the energies emitted in the most energetic astrophysical
events, such as giant flares on magnetars and possibly even short Gamma ray
bursts (GRB), for which the mechanism analyzed here also has the fast
time-scales required.


title: Discovery of an Extreme MeV Blazar with the Swift Burst Alert Telescope

abstract:
  The Burst Alert Telescope (BAT) onboard Swift detected bright emission from
15--195 keV from the source SWIFT~J0746.3+2548 (J0746 in the following),
identified with the optically-faint (R ~ 19), z=2.979 quasar SDSS
J074625.87+244901.2. Here we present Swift and multiwavelength observations of
this source. The X-ray emission from J0746 is variable on timescales of hours
to weeks in 0.5--8 keV and of a few months in 15--195 keV, but there is no
accompanying spectral variability in the 0.5--8 keV band. There is a suggestion
that the BAT spectrum, initially very hard (photon index Gamma ~ 0.7),
steepened to Gamma ~ 1.3 in a few months, together with a decrease of the
15--195 keV flux by a factor ~ 2. The 0.5--8 keV continuum is well described by
a power law with Gamma ~ 1.3, and spectral flattening below 1 keV. The latter
can be described with a column density in excess of the Galactic value with
intrinsic column density N_H^z ~ 10^22 cm-2, or with a flatter power law,
implying a sharp (DeltaGamma >= 1) break across 16 keV in the quasar's
rest-frame. The Spectral Energy Distribution of J0746 is double-humped, with
the first component peaking at IR wavelengths and the second component at MeV
energies. These properties suggest that J0746 is a a blazar with high gamma-ray
luminosity and low peak energy (MeV) stretching the blazar sequence to an
extreme.


title: Coleman-Weinberg Potential In Good Agreement With WMAP

abstract:
  We briefly summarize and update a class of inflationary models from the early
eighties based on a quartic (Coleman-Weinberg) potential for a gauge singlet
scalar (inflaton) field. For vacuum energy scales comparable to the grand
unification scale, the scalar spectral index n_s=0.94-0.97, in very good
agreement with the WMAP three year results. The tensor to scalar ratio r<~0.14,
while alpha=dn/dlnk is =~-10^-3. An SO(10) version naturally explains the
observed baryon asymmetry via non-thermal leptogenesis.


title: Remarkable non-dipolar magnetic field of the Bp star HD 137509

abstract:
  The southern magnetic Bp star HD 137509 exhibits complex rotational
modulation of the longitudinal field and other magnetic observables.
Interpretation of this magnetic variability in the framework of the low-order
multipolar field models suggests a very strong quadrupolar component to
dominate the surface field topology of HD 137509. I have examined the
high-quality VLT/UVES spectra of HD 137509 and discovered resolved Zeeman split
components in some of the spectral lines. The inferred mean surface field
modulus, <B>=29 kG, agrees with the multipolar model predictions. This confirms
the presence of an extremely strong non-dipolar magnetic field in HD 137509 and
establishes this star as the object with the second-largest field among
magnetic chemically peculiar stars.


title: SN 2006aj and the nature of low-luminosity gamma-ray bursts

abstract:
  We present SMARTS consortium optical/IR light curves of SN 2006aj associated
with GRB 060218. We find that this event is broadly similar to two previously
observed events SN 1998bw/GRB 980425 and SN 2003lw/GRB 031203. In particular,
all of these events are greatly under-luminous in gamma-rays compared to
typical long-duration GRBs. We find that the observation by Swift of even one
such event implies a large enough true event rate to create difficulties in
interpreting these events as typical GRBs observed off-axis. Thus these events
appear to be intrinsically different from and much more common than
high-luminosity GRBs, which have been observed in large numbers out to a
redshift of at least 6.3. The existence of a range of intrinsic energies of
GRBs may present challenges to using GRBs as standard candles.


title: The Impact of Cosmic Dust on Supernova Cosmology

abstract:
  Extinction by intergalactic gray dust introduces a magnitude redshift
dependent offset in the standard-candle relation of SN Ia. This leads to
overestimated luminosity distances compared to a dust-free universe.
Quantifying the amplitude of this systematic effect is crucial for an accurate
determination of the dark energy parameters. In this paper we model the gray
dust extinction in terms of the star-formation history of the universe and the
physical properties of the dust grains. We focus on a class of cosmic dust
models which satisfy current observational constraints. These can produce an
extinction as large as 0.08 mag at z=1.7 and potentially disrupt the dark
energy parameter inference from future SN surveys. In particular depending on
the dust model we find that an unaccounted extinction can bias the estimation
of a constant dark energy equation of state w by shifting its best fit value up
to 20% from its true value. Near-IR broadband photometry will hardly detect
this effect, while the induced decrement of the Balmer lines requires high
signal-to-noise spectra. Indeed IR-spectroscopy will be needed for high
redshift SNe. Cosmic dust extinction may also cause a detectable violation of
the distance-duality relation. A more comprehensive knowledge of the physics of
the IGM is necessary for an accurate modeling of intergalactic dust. Due to the
large magnitude dispersion current luminosity distance measurements are
insensitive to such possible extinction effects. In contrast these must be
taken into account if we hope to disclose the true nature of dark energy with
the upcoming generation of SN Ia surveys.


title: Infrared Sources in the Small Magellanic Cloud: First Results

abstract:
  We have imaged the entire Small Magellanic Cloud (SMC), one of the two
nearest star-forming dwarf galaxies, in all seven IRAC and MIPS bands. The low
mass and low metallicity (1/6 solar) of the SMC make it the best local analog
for primitive galaxies at high redshift. By studying the properties of dust and
star formation in the SMC at high resolution, we can gain understanding of
similar distant galaxies that can only be observed in much less detail. In this
contribution, we present a preliminary analysis of the properties of point
sources detected in the Spitzer Survey of the Small Magellanic Cloud (S^3MC).
We find ~400,000 unresolved or marginally resolved sources in our IRAC images,
and our MIPS 24 micron mosaic contains ~17,000 point sources. Source counts
decline rapidly at the longer MIPS wavelengths. We use color-color and
color-magnitude diagrams to investigate the nature of these objects,
cross-correlate their positions with those of known sources at other
wavelengths, and show examples of how these data can be used to identify
interesting classes of objects such as carbon stars and young stellar objects.
For additional examples of some of the questions that can be studied with these
data, please see the accompanying contributions by the other members of our
team. The mosaic images and point source catalogs we have made have been
released to the public on our website (http://celestial.berkeley.edu/spitzer).


title: Extended Lyman alpha emission around bright quasars

abstract:
  Quasars trace the most massive structures at high redshifts and their
presence may influence the evolution of the massive host galaxies. We study the
extended Lyman alpha emission line regions (EELRs) around seven bright, mostly
radio-quiet quasars (QSOs) at 2.7<z<4.5, and compare luminosities with EELRs
around radio-loud QSOs reported in the literature. Using integral field
spectroscopy, we analyse the morphology and kinematics of the quiescent Lya
EELRs around the QSOs. We find evidence for the presence of EELRs around four
radio-quiet and one radio-loud QSO. All EELRs appear asymmetric and the
optically brightest QSOs also have the brightest Lya nebulae. For the two
brightest nebulae we find velocities between ~600 km s^-1 at the QSO position
to ~200 km s^-1 at a distance of 3-4 arcsec from the QSO and surface flux
densities up to 2-3*10^{-16} erg cm^-2 s^-1 arcsec^-2. The five EELRs have
total Lya luminosities which correspond to ~0.5% of the luminosities from the
QSOs broad Lya emission lines. This fraction is an order of magnitude smaller
than found for EELRs around radio-loud, steep spectrum QSOs reported in the
literature. While the nebulae luminosities are correlated with the QSO Lya
luminosities, we find that nebulae luminosities are not correlated with the
central QSO ionising fluxes. The presence of gas in the EELRs can be
interpreted based on two competing scenarios: either from quasar feedback
mechanisms, or from infalling matter. Apart from these two effects, the Lya
flux around radio-loud objects can be enhanced due to interactions with the
radio jets. The relatively fainter nebulae around radio-quiet QSOs compared to
lobe-dominated radio-loud QSOs can be ascribed to this effect, or to
significant differences in the environments between the two classes.


title: Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems

abstract:
  We present results of a reconnaissance for stellar companions to all 131
radial-velocity-detected candidate extrasolar planetary systems known as of
July 1, 2005. CPM companions were investigated using the multi-epoch DSS
images, and confirmed by matching the trigonometric parallax distances of the
primaries to companion distances estimated photometrically. We also attempt to
confirm or refute companions listed in the Washington Double Star Catalog, the
Catalogs of Nearby Stars, in Hipparcos results, and in Duquennoy & Mayor
(1991).
  Our findings indicate that a lower limit of 30 (23%) of the 131 exoplanet
systems have stellar companions. We report new stellar companions to HD 38529
and HD 188015, and a new candidate companion to HD 169830. We confirm many
previously reported stellar companions, including six stars in five systems
that are recognized for the first time as companions to exoplanet hosts. We
have found evidence that 20 entries in the Washington Double Star Catalog are
not gravitationally bound companions. At least three, and possibly five, of the
exoplanet systems reside in triple star systems. Three exoplanet systems have
potentially close-in stellar companions ~ 20 AU away from the primary. Finally,
two of the exoplanet systems contain white dwarf companions. This comprehensive
assessment of exoplanet systems indicates that solar systems are found in a
variety of stellar multiplicity environments - singles, binaries, and triples;
and that planets survive the post-main-sequence evolution of companion stars.


title: Intrinsic Brightness Temperatures of AGN Jets

abstract:
  We present a new method for studying the intrinsic brightness temperatures of
the parsec-scale jet cores of Active Galactic Nuclei (AGN). Our method uses
observed superluminal motions and observed brightness temperatures for a large
sample of AGN to constrain the characteristic intrinsic brightness temperature
of the sample as a whole. To study changes in intrinsic brightness temperature,
we assume that the Doppler factors of individual jets are constant in time as
justified by their relatively small changes in observed flux density. We find
that in their median-low brightness temperature state, the sources in our
sample have a narrow range of intrinsic brightness temperatures centered on a
characteristic temperature, T_int = 3 x 10^10 K, which is close to the value
expected for equipartition, when the energy in the radiating particles equals
the energy stored in the magnetic fields. However, in their maximum brightness
state, we find that sources in our sample have a characteristic intrinsic
brightness temperature greater than 2 x 10^11 K, which is well in excess of the
equipartition temperature. In this state, we estimate the energy in radiating
particles exceeds the energy in the magnetic field by a factor of ~ 10^5. We
suggest that the excess of particle energy when sources are in their maximum
brightness state is due to injection or acceleration of particles at the base
of the jet. Our results suggest that the common method of estimating jet
Doppler factors by using a single measurement of observed brightness
temperature and/or the assumption of equipartition may lead to large scatter or
systematic errors in the derived values.


title: Hubble Imaging Excludes Cosmic String Lens

abstract:
  The galaxy image pair CSL-1 has been a leading candidate for a cosmic string
lens. High quality imaging data from the Hubble Space Telescope presented here
show that it is not a lens but a pair of galaxies. The galaxies show different
orientations of their principal axes, not consistent with any lens model. We
present a new direct test of the straight-string lens model, using a displaced
difference of the image from itself to exclude CSL-1 at high confidence.


title: The Possible z=0.83 Precursors of z=0 M* Early-type Cluster Galaxies

abstract:
  We examine the distribution of stellar masses of galaxies in MS 1054-03 and
RX J0152.7-1357, two X-ray selected clusters of galaxies at z=0.83. Our stellar
mass estimates, from spectral energy distribution fitting, reproduce the
dynamical masses as measured from velocity dispersions and half-light radii
with a scatter of 0.2 dex in the mass for early-type galaxies. When we restrict
our sample of members to high stellar masses, > 1e11.1 Msun (M* in the
Schechter mass function for cluster galaxies), we find that the fraction of
early-type galaxies is 79 +/- 6% at z=0.83 and 87 +/- 6% at z=0.023 for the
Coma cluster, consistent with no evolution. Previous work with
luminosity-selected samples finds that the early-type fraction in rich clusters
declines from =~80% at z=0 to =~60% at z=0.8. The observed evolution in the
early-type fraction from luminosity-selected samples must predominately occur
among sub-M* galaxies. As M* for field and group galaxies, especially
late-types, is below M* for clusters galaxies, infall could explain most of the
recent early-type fraction growth. Future surveys could determine the
morphological distributions of lower mass systems which will confirm or refute
this explanation.


title:
A Fundamental Relation Between Compact Stellar Nuclei, Supermassive
  Black Holes, and Their Host Galaxies

abstract:
  Imaging surveys with the Hubble Space Telescope (HST) have shown that roughly
50-80% of low- and intermediate-luminosity galaxies contain a compact stellar
nucleus at their center, regardless of host galaxy morphological type. We
combine HST imaging for early-type galaxies from the ACS Virgo Cluster Survey
with ground-based long-slit spectra from KPNO to show that the masses of
compact stellar nuclei in Virgo Cluster galaxies obey a tight correlation with
the masses of the host galaxies. The same correlation is obeyed by the
supermassive black holes (SBHs) found in predominantly massive galaxies. The
compact stellar nuclei in the Local Group galaxies M33 and NGC205 are also
found to fall along this same scaling relation. These results indicate that a
generic by-product of galaxy formation is the creation of a Central Massive
Object (CMO) -- either a SBH or a compact stellar nucleus -- that contains a
mean fraction, ~ 0.2%, of the total galactic mass. In galaxies with masses
greater than a few times 10^10 solar masses, SBHs appear to be the dominant
mode of CMO formation.


title: Magnetic field effects in the heat flow of charged fluids

abstract:
  Heat conduction in ionized plasmas in the presence of magnetic fields is
today a fashionable problem. The kinetic theory of plasmas, in the context of
non-equilibrium thermodynamics, predicts a Hall-effect-like heat flow due to
the presence of a magnetic field in ionized gases. This cross effect, the
Righi-Leduc effect together with a heat flow perpendicular to the magnetic
field are shown to yield significant contributions, under certain conditions to
the ordinary Fourier component of the heat flow. The thermal conductivities
associated with these effects change with the strength of the magnetic field
for a given temperature and density and are shown to be significant compared
with the parallel conductivity for a whole range of values of \vec{B}.


title:
OVI Asymmetry and an Accelerated Outflow in an Obscured Seyfert: FUSE
  and HST STIS Spectroscopy of Markarian533

abstract:
  We present far-ultraviolet spectra of the Seyfert2 galaxy Mrk533 obtained
with FUSE. These spectra show narrow asymmetrical OVI 1032,1038 emission lines
with stronger wings shortward of the peak wavelength, but the degree of
asymmetry of these wings in velocity is much lower than that of the wings of
the lines of lower ionization. In the combined OVI profile there are marginal
indications of local absorptions in the outflow. The CIII 977 line is seen
weakly with a similar profile, but with very low signal to noise. These FUV
spectra are among the first for a Seyfert of type2, i.e., a purportedly
obscured Seyfert. The HST STIS spectral image of Mrk533 allows delineation of
the various components of the outflow, and we infer that the outflow is
accelerated. We discuss the results in terms of nuclear geometry and
kinematics.


title: Kinematics of SiO J=8-7 Emission towards the HH 212 Jet

abstract:
  We present SiO J=8-7 (347.3 GHz) observations towards HH 212 using the ASTE
telescope. Our observations with a 22''-diameter beam show that the SiO
emission is highly concentrated within 1' of the driving source. We carefully
compare the SiO observations with archival H_2 1-0 S(1) images and published
H_2 echelle spectra. We find that, although the SiO velocities closely match
the radial velocities seen in H_2, the distribution of H_2 and SiO emission
differ markedly. We attribute the latter to the different excitation conditions
required for H_2 and SiO emission, particularly the higher critical density
(n_H2 ~10^8 cm^-3) of the SiO J=8-7 emission. The kinematic similarities imply
that the H_2 and SiO are associated with the same internal working surfaces. We
conclude that the SiO J=8-7 emission has a potential to probe the jet/wind
launching region through interferometric observations in the future,
particularly for the youngest, most deeply embedded protostars where IR
observations are not possible.


title:
Fast and Efficient Template Fitting of Deterministic Anisotropic
  Cosmological Models Applied to WMAP Data

abstract:
  We explore methods of fitting templates to cosmic microwave background (CMB)
data, and in particular demonstrate the application of the total convolver
algorithm as a fast method of performing a search over all possible locations
and orientations of the template relative to the sky. This analysis includes
investigation of issues such as chance alignments and foreground residuals. We
apply these methods to compare Bianchi models of type VII_h to WMAP first year
data and confirm the basic result of our 2005 paper.


title: Producing ultra-strong magnetic fields in neutron star mergers

abstract:
  We report an extremely rapid mechanism for magnetic field amplification
during the merger of a binary neutron star system. This has implications for
the production of the short class of Gamma-Ray Bursts, which recent
observations suggest may originate in such mergers. In detailed
magnetohydrodynamic simulations of the merger process, the fields are amplified
via Kelvin-Helmholtz instabilities beyond magnetar field strength and may
therefore represent the strongest magnetic fields in the Universe. The
amplification occurs in the shear layer which forms between the neutron stars
and on a time scale of only 1 millisecond, i.e. long before the remnant can
collapse into a black hole.


title:
Full evolutionary models for PG1159 stars. Implications for the
  helium-rich O(He) stars

abstract:
  We present full evolutionary calculations appropriate to post-AGB PG1159
stars for a wide range of stellar masses.
  We take into account the complete evolutionary stages of PG1159 progenitors
starting from the Zero Age Main Sequence. We consider the two kinds of Born
Again Scenarios, the very late thermal pulse (VLTP) and the late thermal pulse
(LTP), that give rise to hydrogen-deficient compositions. The location of our
PG1159 tracks in the effective temperature - gravity diagram and their
comparison with previous calculations as well as the resulting surface
compositions are discussed at some length.
  Our results reinforce the idea that the different abundances of $^{14}$N
observed at the surface of those PG1159 stars with undetected hydrogen is an
indication that the progenitors of these stars would have evolved through a
VLTP episode, where most of the hydrogen content of the remnant is burnt, or
LTP, where hydrogen is not burnt but instead diluted to very low surface
abundances. We derive new values for spectroscopical masses based on these new
models. We discuss the correlation between the presence of planetary nebulae
and the $^{14}$N abundance as another indicator that $^{14}$N-rich objects
should come from a VLTP episode while $^{14}$N-deficient ones should be the
result of a LTP. Finally, we discuss an evolutionary scenario that could
explain the existence of PG1159 stars with unusually high helium abundances and
a possible evolutionary connection between these stars and the low mass O(He)
stars.


title:
A non-linear resonance model for the black hole and neutron star QPOs:
  theory supported by observations

abstract:
  Kilohertz Quasi-Periodic Oscillations (QPOs) have been detected in many
accreting X-ray binaries. It has been suggested that the highest QPO
frequencies observed in the modulation of the X-ray flux reflect a non-linear
resonance between two modes of accreting disk oscillation. This hypothesis
implies certain very general predictions, several of which have been borne out
by observations. Some of these follow from properties of non-linear
oscillators, while the others are specific to oscillations of fluid in strong
gravity. A 3:2 resonant ratio of frequencies can be clearly recognized in the
black-hole as well as in the neutron-star QPO data.


title:
Observational constraints on modified gravity models and the Poincar\'e
  dodecahedral topology

abstract:
  We study the constraints that spatial topology may place on the parameters of
models that account for the accelerated expansion of the universe via infrared
modifications to general relativity, namely the Dvali-Gabadadze-Porrati
braneworld model as well as the Dvali-Turner and Cardassian models. By
considering the Poincar\'e dodecahedral space as the circles-in-the-sky
observable spatial topology, we examine the constraints that can be placed on
the parameters of each model using type Ia supernovae data together with the
baryon acoustic peak in the large scale correlation function of the Sloan
Digital Sky Survey of luminous red galaxies and the Cosmic Microwave Background
Radiation shift parameter data. We show that knowledge of spatial topology does
provide relevant constraints, particularly on the curvature parameter, for all
models.


title: The K-band properties of Seyfert 2 galaxies

abstract:
  It is well known that the [O {\sc iii}]$\lambda$5007 emission line and hard
X-ray(2-10keV) luminosities are good indicators of AGN activities and that the
near and mid-infrared emission of AGN originates from re-radiation of dusty
clouds heated by the UV/optical radiation from the accretion disk. In this
paper we present a study of the near-infrared K-band (2.2$\mu$m) properties for
a sample of 65 Seyfert 2 galaxies. By using the AGN/Bulge/Disk decomposition
technique, we analyzed the 2MASS K$_{\rm S}$-band images for Seyfert 2 galaxies
in order to derive the K$_{\rm S}$- band magnitudes for the central engine,
bulge, and disk components. We find that the K$_{\rm S}$-band magnitudes of the
central AGN component in Seyfert 2 galaxies are tightly correlated with the [O
{\sc iii}]$\lambda$5007 and the hard X-ray luminosities, which suggests that
the AGN K-band emission is also an excellent indicator of the nuclear
activities at least for Seyfert 2 galaxies. We also confirm the good relation
between the central black hole masses and bulge's K-band magnitudes for Seyfert
2s.


title:
A Study of Compact Radio Sources in Nearby Face-on Spiral Galaxies. I.
  Long Term Evolution of M83

abstract:
  We present analyses of deep radio observations of M83 taken with the Very
Large Array spanning fifteen years, including never before published
observations from 1990 and 1998. We report on the evolution of 55 individual
point sources, which include four of the six known historical supernovae in
this galaxy. A total of 10 sources have X-ray counterparts from a {\em Chandra}
survey. Each of these sources show non-thermal spectral indices, and most
appear to be X-ray supernova remnants. Comparing the radio source list to
surveys in optical and X-ray, we identify three optical/X-ray supernova
remnants. Nearly half of the detected radio sources in these observations are
coincident with known H II regions lying in the spiral arm structures of the
galaxy. We also report on changes in emission from the complex nuclear region,
which has shown variability at 20cm wavelengths. We confirm that the peak radio
emission from the nucleus is not coincident with the known optical center. One
lesser nuclear peak is consistent with the optical/IR nucleus. Previous
dynamical studies of a ``dark'' nuclear mass indicate a possible match to other
radio nuclear emission regions in M83.


title: Coupling the dynamics and the molecular chemistry in the Galactic center

abstract:
  The physical conditions of the Galactic center (GC) clouds moving with
non-circular velocities are not well-known. We have studied the physical
conditions of these clouds with the aim of better understanding the origin of
the outstanding physical conditions of the GC molecular gas and the possible
effect of the large scale dynamics on these physical conditions.Using published
CO(1-0) data, we have selected a set of clouds belonging to all the kinematical
components seen in the longitude-velocity diagram of the GC. We have done a
survey of dense gas in all the components using the J=2-1 lines of CS and SiO
as tracers of high density gas and shock chemistry. We have detected CS and SiO
emission in all the kinematical components. The gas density and the SiO
abundance of the clouds in non-circular orbits are similar those in the nuclear
ring (GCR). Therefore, in all the kinematical components there are dense clouds
that can withstand the tidal shear. However, there is no evidence of star
formation outside the GCR. The high relative velocity and shear expected in the
dust-lanes along the bar major axis could inhibit the star formation process,
as observed in other galaxies. The high SiO abundances derived in the
non-circular velocity clouds are likely due to the large-scale shocks that
created the dust lanes


title: The Ring Imaging Cherenkov detector (RICH) of the AMS experiment

abstract:
  The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the
International Space Station (ISS) will be equipped with a proximity focusing
Ring Imaging Cherenkov (RICH) detector for measuring the electric charge and
velocity of the charged cosmic particles. A RICH prototype consisting of 96
photomultiplier units, including a piece of the conical reflector, was built
and its performance evaluated with ion beam data. Preliminary results of the
in-beam tests performed with ion fragments resulting from collisions of a 158
GeV/c/nuc primary beam of Indium ions (CERN SPS) on a Pb target are reported.
The collected data included tests to the final front-end electronics and to
different aerogel radiators. Cherenkov rings for a large range of charged
nuclei and with reflected photons were observed. The data analysis confirms the
design goals. Charge separation up to Fe and velocity resolution of the order
of 0.1% for singly charged particles are obtained.


title:
X-ray emission from the double neutron star binary B1534+12: Powered by
  the pulsar wind?

abstract:
  We report the detection of the double neutron star binary (DNSB) B1534+12 (=
J1537+1155) with the Chandra X-ray Observatory. This DNSB (orbital period 10.1
hr) consists of the millisecond (recycled) pulsar J1537+1155A (P_A=37.9 ms) and
a neutron star not detected in the radio. After the remarkable double pulsar
binary J0737-3039, it is the only other DNSB detected in X-rays. We measured
the flux of (2.2\pm 0.6)\times10^{-15} ergs s^{-1} cm^{-2} in the 0.3-6 keV
band. The small number of collected counts allows only crude estimates of
spectral parameters. The power-law fit yields the photon index of 3.2\pm 0.5
and the unabsorbed 0.2-10 keV luminosity L_X=6\times10^{29} ergs s^{-1} =
3\times 10^{-4}Edot_A, where Edot_A is the spin-down power of J1537+1155A.
Alternatively, the spectrum can be fitted by a blackbody model with T = 2.2 MK
and the projected emitting area of ~ 5\times 10^3 m^2. The distribution of
photon arrival times over binary orbital phase shows a deficit of X-ray
emission around apastron, which suggests that the emission is caused by
interaction of the relativistic wind from J1537+1155A with its neutron star
companion. We also reanalyzed the Chandra and XMM-Newton observations of
J0737-3039 and found that its X-ray spectrum is similar to the spectrum of
B1534+12, and its X-ray luminosity is about the same fraction of Edot_A, which
suggests similar X-ray emission mechanisms. However, the X-ray emission from
J0737-3039 does not show orbital phase dependence. This difference can be
explained by the smaller eccentricity of J0737-3039 or a smaller misalignment
between the equatorial plane of the millisecond pulsar and the orbital plane of
the binary.


title:
A dynamical model for the heavily ram pressure stripped Virgo spiral
  galaxy NGC 4522

abstract:
  A dynamical model including ram pressure stripping is applied to the strongly
HI deficient Virgo spiral galaxy NGC 4522. A carefully chosen model snapshot is
compared with existing VLA HI observations. The model successfully reproduces
the large-scale gas distribution and the velocity field. However it fails to
reproduce the large observed HI linewidths in the extraplanar component, for
which we give possible explanations. In a second step, we solve the induction
equation on the velocity fields of the dynamical model and calculate the large
scale magnetic field. Assuming a Gaussian distribution of relativistic
electrons we obtain the distribution of polarized radio continuum emission
which is also compared with our VLA observations at 6 cm. The observed maximum
of the polarized radio continuum emission is successfully reproduced. Our model
suggests that the ram pressure maximum occurred only ~50 Myr ago. Since NGC
4522 is located far away from the cluster center (~1 Mpc) where the
intracluster medium density is too low to cause the observed stripping if the
intracluster medium is static and smooth, two scenarios are envisaged: (i) the
galaxy moves very rapidly within the intracluster medium and is not even bound
to the cluster; in this case the galaxy has just passed the region of highest
intracluster medium density; (ii) the intracluster medium is not static but
moving due to the infall of the M49 group of galaxies. In this case the galaxy
has just passed the region of highest intracluster medium velocity. This study
shows the strength of combining high resolution HI and polarized radio
continuum emission with detailed numerical modeling of the evolution of the gas
and the large-scale magnetic field.


title: Energy transfer by the scattering of resonant photons

abstract:
  A formal derivation is presented of the energy transfer rate between
radiation and matter due to the scattering of an isotropic distribution of
resonant photons. The derivation is developed in the context of the two-level
atom in the absence of collisions and radiative transitions to and from the
continuum, but includes the full angle-averaged redistribution function for
photon scattering. The result is compared with previous derivations, all of
which have been based on the Fokker-Planck approximation to the radiative
transfer equation. A new Fokker-Planck approximation, including an extension to
higher (post-diffusive) orders, is derived to solve the radiative transfer
equation, and time-dependent numerical solutions are found. The relaxation of
the colour temperature to the matter temperature is computed as the radiation
field approaches statistical equilibrium through scattering. The results are
discussed in the context of the Wouthuysen-Field mechanism for coupling the
21cm spin temperature of neutral hydrogen to the kinetic temperature of the gas
through LyA scattering. The evolution of the heating rate is also computed, and
shown to diminish as the gas approaches statistical equilibrium.


title:
The formation of massive stars: accretion, disks and the development of
  hypercompact HII regions

abstract:
  The hypothesis that massive stars form by accretion can be investigated by
simple analytical calculations that describe the effect that the formation of a
massive star has on its own accretion flow. Within a simple accretion model
that includes angular momentum, that of gas flow on ballistic trajectories
around a star, the increasing ionization of a massive star growing by accretion
produces a three-stage evolutionary sequence. The ionization first forms a
small quasi-spherical HII region gravitationally trapped within the accretion
flow. At this stage the flow of ionized gas is entirely inward. As the
ionization increases, the HII region transitions to a bipolar morphology in
which the inflow is replaced by outflow within a narrow range of angle with
about the bipolar axis. At higher rates of ionization, the opening angle of the
outflow region progressively increases. Eventually, in the third stage, the
accretion is confined to a thin region about an equatorial disk. Throughout
this early evolution, the HII region is of hypercompact to ultracompact size
depending on the mass of the enclosed star or stars. These small HII regions
whose dynamics are dominated by stellar gravitation and accretion are different
than compact and larger HII regions whose dynamics are dominated by the thermal
pressure of the ionized gas.


title: Numerical simulations of coronal magnetic field loop evolution

abstract:
  We present the results of the numerical simulations of the interaction
between a magnetized star and an imperfectly conducting accretion disk. To
analyze the ''star-disk'' interaction we numerically investigate the MHD
equations used Godunov-type high resolution numerical method. It was found that
the ''star-disk'' interaction occurs with quasi-periodic reconnection of the
magnetic field coronal loops and plasmoid ejections. In the case of the perfect
disk conductivity the evolution of the coronal magnetic field leads to the
periodic outflow of angular momentum from the disk. In the case of an
imperfectly conducting disk the configuration of the magnetic field is formed
such that the disk angular momentum carried by magnetic field gets balanced by
angular momentum carried by matter.


title:
Na-O Anticorrelation And HB. III. The abundances of NGC 6441 from
  FLAMES-UVES spectra

abstract:
  The aim of the present work is to determine accurate metallicities for a
group of red giant branch stars in the field of the bulge Globular Cluster NGC
6441. This is the third paper of a series resulting from a large project aimed
at determining the extent of the Na-O anticorrelation among Globular Cluster
stars and exploring its relationship with HB morphology. We present an LTE
abundance analysis of these objects, based on data gathered with the FLAMES
fiber facility and the UVES spectrograph at VLT2. Five of the thirteen stars
observed are members of the cluster. The average Fe abundance for these five
stars is [Fe/H]=$-0.39\pm 0.04\pm 0.05$~dex, where the first error bar includes
the uncertainties related to star-to-star random errors, and the second one the
systematic effects related to the various assumptions made in the analysis.The
overall abundance pattern is quite typical of Globular Clusters, with an excess
of the $\alpha-$elements and of Eu. There is evidence that the stars of NGC
6441 are enriched in Na and Al, while they have been depleted of O and Mg, due
to H-burning at high temperatures, in analogy with extensive observations for
other Globular Clusters: in particular, one star is clearly Na and Al-rich and
O and Mg-poor. We obtained also quite high V abundances, but it is possible
that this is an artifact of the analysis, since similar large V abundances are
derived also for the field stars. These last are all more metal-rich than NGC
6441 and probably belong to the bulge population.


title: The non-Gaussian Cold Spot in the 3-year WMAP data

abstract:
  The non-Gaussian cold spot detected in wavelet space in the WMAP 1-year data,
is detected again in the coadded WMAP 3-year data at the same position (b =
-57, l = 209) and size in the sky (around 10 degrees). The present analysis is
based on several statistical methods: kurtosis, maximum absolute temperature,
number of pixels below a given threshold, volume and Higher Criticism. All
these methods detect deviations from Gaussianity in the 3--year data set at a
slightly higher confidence level than in the WMAP 1-year data. These small
differences are mainly due to the new foreground reduction technique and not to
the reduction of the noise level, which is negligible at the scale of the spot.
In order to avoid "a posteriori" analyses, we recalculate for the WMAP 3-year
data the significance of the deviation in the kurtosis. The skewness and
kurtosis tests were the first tests performed with wavelets for the WMAP data.
We obtain that the probability of finding an at least as high deviation in
Gaussian simulations is 1.85%. The frequency dependence of the spot is shown to
be extremely flat. Galactic foreground emissions are not likely to be
responsible for the detected deviation from Gaussianity.


title:
Hot Dust and PAH Emission at Low Metallicity: A Spitzer Survey of Local
  Group and Other Nearby Dwarf Galaxies

abstract:
  We present Spitzer Space Telescope 4.5 and 8.0 micron imaging of 15 Local
Group and nearby dwarf galaxies. Our sample spans a range of more than one dex
in nebular metallicity and over three orders of magnitude in current star
formation rate, allowing us to examine the dependence of the diffuse 8 micron
emission, originating from hot dust and PAHs, on these parameters. We detect
prominent diffuse 8 micron emission in four of the most luminous galaxies in
the sample (IC 1613, IC 5152, NGC 55, and NGC 3109), low surface brightness
emission from four others (DDO 216, Sextans A, Sextans B, WLM), and no diffuse
emission from the remaining objects. We observe general correlations of the
diffuse 8 micron emission with both the current star formation rate and the
nebular metallicity of the galaxies in our sample. However, we also see
exceptions to these correlations that suggest other processes may also have a
significant effect on the generation of hot dust/PAH emission. These systems
all have evidence for old and intermediate age star formation, thus the lack of
diffuse 8 micron emission cannot be attributed to young galaxy ages. Also, we
find that winds are unlikely to explain the paucity of diffuse 8 micron
emission, since high resolution imaging of the neutral gas in these objects
show no evidence of blowout. Additionally, we propose the lack of diffuse 8
micron emission in low-metallicity systems may be due to the destruction of
dust grains by supernova shocks, assuming the timescale to regrow dust grains
and PAH molecules is long compared to the destruction timescale. The most
likely explanation for the observed weak diffuse 8 micron emission is at least
partly due to a general absence of dust (including PAHs), in agreement with
their low metallicities.


title:
Potential sources of contamination to weak lensing measurements:
  constraints from N-body simulations

abstract:
  We investigate the expected correlation between the weak gravitational shear
of distant galaxies and the orientation of foreground galaxies, through the use
of numerical simulations. This shear-ellipticity correlation can mimic a
cosmological weak lensing signal, and is potentially the limiting physical
systematic effect for cosmology with future high-precision weak lensing
surveys. We find that, if uncorrected, the shear-ellipticity correlation could
contribute up to 10% of the weak lensing signal on scales up to 20 arcminutes,
for lensing surveys with a median depth z=1. The most massive foreground
galaxies are expected to cause the largest correlations, a result also seen in
the Sloan Digital Sky Survey. We find that the redshift dependence of the
effect is proportional to the lensing efficiency of the foreground, and this
offers prospects for removal to high precision, although with some model
dependence. The contamination is characterised by a weakly negative B-mode,
which can be used as a diagnostic of systematic errors. We also provide more
accurate predictions for a second potential source of error, the intrinsic
alignment of nearby galaxies. This source of contamination is less important,
however, as it can be easily removed with distance information.


title: The University of Hawaii Wide Field Imager (UHWFI)

abstract:
  The University of Hawaii Wide-Field Imager (UHWFI) is a focal compressor
system designed to project the full half-degree field of the UH 2.2 m telescope
onto the refurbished UH 8Kx8K CCD camera. The optics use Ohara glasses and are
mounted in an oil-filled cell to minimize light losses and ghost images from
the large number of internal lens surfaces. The UHWFI is equipped with a
six-position filter wheel and a rotating sector blade shutter,both driven by
stepper motors. The instrument saw first light in 2004 in an engineering mode.
After filling the lens cell with index matching oil, integration of all
software components into the user interface, tuning of the CCD performance, and
the purchase of the final filter set, UHWFI is now fully commissioned at the UH
2.2 m telescope.


title: Is Radiation of Quantized Black Holes Observable?

abstract:
  If primordial black holes (PBH) saturate the present upper limit on the dark
matter density in our Solar system and if their radiation spectrum is discrete,
the sensitivity of modern detectors is close to that necessary for detecting
this radiation. This conclusion is not in conflict with the upper limits on the
PBH evaporation rate.


title: TeV Neutrinos from SuperNova Remnants embedded in Giant Molecular Clouds

abstract:
  The recent detection of $\gamma$-rays with energy up to 10 TeV from dense
regions surrounding some Supernova Remnants (SNR) provides strong, though still
not conclusive, evidence that the nucleonic component of galactic Cosmic Rays
is accelerated in the supernova outflows. Neutrino telescopes could further
support the validity of such scenario by detecting neutrinos coming from the
same regions. We re-evaluate the TeV range neutrino-photon flux ratio to be
expected from pion decay, finding small differences respect to previous
derivations. We apply our results and the recent HESS measurements of the very
high energy $\gamma$-ray flux from the molecular cloud complex in the Galactic
Centre, to estimate the neutrino flux from that region discussing the
detectability perspectives for Mediterranean Neutrino Telescopes. We also
discuss under which conditions neutron decay may give rise to a significant TeV
antineutrino flux from a SNR embedded in Molecular Cloud complexes.


title: Fomin's conception of quantum cosmogenesis

abstract:
  The main aim of this paper is to extend the early approach to quantum
cosmogenesis provided by Fomin. His approach was developed independently to the
well-known Tryon description of the creation of the closed universe as a
process of quantum fluctuation of vacuum. We apply the Fomin concept to derive
the cosmological observables. We argue that Fomin's idea from his 1973 work, in
contrast to Tryon's one has impact on the current Universe models and the
proposed extension of his theory now can be tested by distant supernovae SNIa.
Fomin's idea of the creation of the Universe is based on the intersection of
two fundamental theories: general relativity and quantum field theory with the
contemporary cosmological models with dark energy. As a result of comparison
with contemporary approaches concerning dark energy, we found out that Fomin's
idea appears in the context of the present acceleration of the Universe
explanation: cosmological models with decaying vacuum. Contemporary it appears
in the form of Ricci scalar dark energy connected with the holographic
principle. We show also that the Fomin model admits the bounce instead of the
initial singularity. We demonstrate that the Fomin model of cosmogenesis can be
falsified and using SNIa data the values of model parameters is in agreement
with observations.


title: Probing T Tauri Accretion and Outflow with 1 Micron Spectroscopy

abstract:
  In a high dispersion 1 micron survey of 39 classical T Tauri stars veiling is
detected in 80%, and He I 10830 and Pgamma line emission in 97% of the stars.
On average, the 1 micron veiling exceeds the level expected from previously
identified sources of excess emission, suggesting the presence of an additional
contributor to accretion luminosity in the star-disk interface region.
Strengths of both lines correlate with veiling, and at Pgamma there is a
systematic progression in profile morphology with veiling. He I 10830 has an
unprecedented sensitivity to inner winds, showing blueshifted absorption below
the continuum in 71% of the CTTS compared to 0% at pgamma. This line is also
sensitive to magnetospheric accretion flows, with redshifted absorption below
the continuum found in 47% of the CTTS compared to 24% at Pgamma. The
blueshifted absorption at 10830 shows considerable diversity in its breadth and
penetration depth into the continuum, indicating that a range of inner wind
conditions exist in accreting stars. We interpret the broadest and deepest blue
absorptions as formed from scattering of the 1 micron continuum by outflowing
gas whose full acceleration region envelopes the star, suggesting radial
outflow from the star. In contrast, narrow blue absorption with a range of
radial velocities more likely arises via scattering of the 1 micron continuum
by a wind emerging from the inner disk. Both stellar and disk winds are
accretion powered since neither is seen in non-accreting WTTS and among the
CTTS helium strength correlates with veiling.


title:
Mid-Infrared Spectral Diagnostics of Nuclear and Extra-Nuclear Regions
  in Nearby Galaxies

abstract:
  Mid-infrared diagnostics are presented for a large portion of the Spitzer
Infrared Nearby Galaxies Survey (SINGS) sample plus archival data from the
Infrared Space Observatory and the Spitzer Space Telescope. Our main result is
that these mid-infrared diagnostics effectively constrain a target's dominant
power source. The combination of a high ionization line index and PAH strength
serves as an efficient discriminant between AGN and star-forming nuclei,
confirming progress made with ISO spectroscopy on starbursting and
ultraluminous infrared galaxies. The sensitivity of Spitzer allows us to probe
fainter nuclei and star-forming regions within galaxy disks. We find that both
star-forming nuclei and extranuclear regions stand apart from nuclei that are
powered by Seyfert or LINER activity. In fact, we identify areas within four
diagnostic diagrams containing >90% Seyfert/LINER nuclei or >90% HII
regions/HII nuclei. We also find that, compared to starbursting nuclei,
extranuclear regions typically separate even further from AGN, especially for
low-metallicity extranuclear environments. In addition, instead of the
traditional mid-infrared approach to differentiating between AGN and
star-forming sources that utilizes relatively weak high-ionization lines, we
show that strong low-ionization cooling lines of X-ray dominated regions like
[SiII] 34.82 micron can alternatively be used as excellent discrimants.
Finally, the typical target in this sample shows relatively modest interstellar
electron density (~400 cm^{-3}) and obscuration (A_V ~ 1.0 mag for a foreground
screen), consistent with a lack of dense clumps of highly obscured gas and dust
residing in the emitting regions. [Abridged]


title: Mid-Infrared Spectral Diagnostics of Nearby Galaxies

abstract:
  The Spitzer Space Telescope is pushing into new frontiers in high redshift
astronomy. Closer to home, Spitzer is making an equally large impact on our
understanding of galaxy formation and evolution. In this contribution we
present mid-infrared diagnostics based largely on data from the Spitzer
Infrared Nearby Galaxies Survey (SINGS). Our main result is that these
mid-infrared diagnostics effectively constrain a target's dominant power
source. The combination of a high ionization line index and PAH strength serves
as an efficient discriminant between AGN and star-forming nuclei, confirming
progress made with ISO spectroscopy on starbursting and ultraluminous infrared
galaxies. The sensitivity of Spitzer allows us to probe fainter nuclei and
star-forming regions within galaxy disks. We find that both star-forming nuclei
and extranuclear regions stand apart from nuclei that are powered by Seyfert or
LINER activity. In fact, we identify areas within three diagnostic diagrams
containing >90% Seyfert/LINER nuclei or >90% HII regions/HII nuclei. We also
find that, compared to starbursting nuclei, extranuclear regions typically
separate even further from AGN, especially for low-metallicity extranuclear
environments. In addition, instead of the traditional mid-infrared approach to
differentiating between AGN and star-forming sources that utilizes relatively
weak high-ionization lines, we show that strong low-ionization cooling lines of
X-ray dominated regions like [SiII] 34.82 micron can alternatively be used as
excellent discrimants.


title:
Chemical abundances in LMC stellar populations I. The Inner disk sample
  Based on observations collected at the VLT UT2 telescope

abstract:
  The advent of the new class 8 meters telescopes allows for the first time the
detailed study of numerous stars of galaxies other than our own. The Large
Magellanic Cloud is one of the most interesting targets due to its proximity
and its relatively face-on disk, permitting to separate populations pertaining
to the different structures of the galaxy. We have used FLAMES (the Fibre Large
Array Multi Element Spectrograph) at the VLT-UT2 telescope to obtain spectra of
a large sample of stars from the Inner Disk of the LMC, $\sim$2 kpc from the
center of the galaxy. We investigate the chemical abundances of iron-peak
elements, heavy and light $s$-process elements, Cu, Na, Sc and
$\alpha$-elements for a sample of red giant stars. Metallicities for the sample
stars range from [Fe/H] = $-$1.76 to $-$0.02. LMC inner disk stars show a
definitely different chemical pattern when compared to galactic stars of the
same metallicity.


title: Galaxy luminosity function per morphological type up to z=1.2

abstract:
  We have computed the evolution of the rest-frame B-band luminosity function
(LF) for bulge and disk-dominated galaxies since z=1.2. We use a sample of 605
spectroscopic redshifts with I_{AB}<24 in the Chandra Deep Field South from the
VIMOS-VLT Deep Survey, 3555 galaxies with photometric redshifts from the
COMBO-17 multi-color data, coupled with multi-color HST/ACS images from the
Great Observatories Origin Deep Survey. We split the sample in bulge- and
disk-dominated populations on the basis of asymmetry and concentration
parameters measured in the rest-frame B-band. We find that at z=0.4-0.8, the LF
slope is significantly steeper for the disk-dominated population (\alpha=-1.19
\pm 0.07) compared to the bulge-dominated population (\alpha=-0.53 \pm 0.13).
The LF of the bulge-dominated population is composed of two distinct
populations separated in rest-frame color: 68% of red (B-I)_{AB}>0.9 and bright
galaxies showing a strongly decreasing LF slope \alpha=+0.55 \pm 0.21, and 32%
of blue (B-I)_{AB}<0.9 and more compact galaxies which populate the LF
faint-end. We observe that red bulge-dominated galaxies are already well in
place at z~1, but the volume density of this population is increasing by a
factor 2.7 between z~1 and z~0.6. It may be related to the building-up of
massive elliptical galaxies in the hierarchical scenario. In addition, we
observe that the blue bulge-dominated population is dimming by 0.7 magnitude
between z~1 and z~0.6. Galaxies in this faint and more compact population could
possibly be the progenitors of the local dwarf spheroidal galaxies.


title: Cosmic Conspiracies

abstract:
  The now standard vanilla-flavoured LambdaCDM model has gained further
confirmation with the release of the 3-year WMAP data combined with several
other cosmological data-sets. As the parameters of this standard model become
known with increasing precision, more of its bizarre features become apparent.
Here we describe some of the strangest of these ostensible coincidences. In
particular we appear to live (within 1sigma) at the precise epoch when the age
of the Universe multiplied by the Hubble parameter H_0 t_0 = 1.


title: White dwarf stars in D dimensions

abstract:
  We determine the mass-radius relation of relativistic white dwarf stars (a
self-gravitating degenerate Fermi gas at T=0) in a D-dimensional universe and
study the influence of the dimension of space on the laws of physics when we
combine quantum mechanics, special relativity and gravity. We exhibit
characteristic dimensions D=1, D=2, D=3, D={1\over 2}(3+\sqrt{17}), D=4,
D=2(1+\sqrt{2}) and show that quantum mechanics cannot balance gravitational
collapse for D\ge 4, even in the non-relativistic regime. This is similar to a
result found by Ehrenfest (1917) at the atomic level for Coulomb forces (in
Bohr's model) and for the Kepler problem. This makes the dimension of our
universe D=3 very particular. We discuss some historic aspects concerning the
discovery of the Chandrasekhar (1931b) limiting mass in relation with previous
investigations by Anderson (1929) and Stoner (1930). We also show the analogy
between the Chandrasekhar limiting mass of white dwarf stars and the critical
mass of biological populations in the two-dimensional chemotactic problem.


title:
Is it possible to observationally distinguish adiabatic Quartessence
  from LambdaCDM?

abstract:
  The equation of state (EOS) in quartessence models interpolates between two
stages: $p\simeq 0$ at high energy densities and $p\approx -\rho$ at small
ones. In the quartessence models analyzed up to now, the EOS is convex,
implying increasing adiabatic sound speed ($c_{s}^{2}$) as the energy density
decreases in an expanding Universe. A non-negligible $c_{s}^{2}$ at recent
times is the source of the matter power spectrum problem that plagued all
convex (non-silent) quartessence models. Viability for these cosmologies is
only possible in the limit of almost perfect mimicry to $\Lambda$CDM. In this
work we investigate if similarity to $\Lambda$CDM is also required in the class
of quartessence models whose EOS changes concavity as the Universe evolves. We
focus our analysis in the simple case in which the EOS has a step-like shape,
such that at very early times $p\simeq0$, and at late times $p\simeq const<0$.
For this class of models a non-negligible $c_{s}^{2}$ is a transient
phenomenon, and could be relevant only at a more early epoch. We show that
agreement with a large set of cosmological data requires that the transition
between these two asymptotic states would have occurred at high redshift
($z_t\gtrsim38$). This leads us to conjecture that the cosmic expansion history
of any successful non-silent quartessence is (practically) identical to the
$\Lambda$CDM one.


title: Transfer matrices for magnetized CMB anisotropies

abstract:
  Large-scale magnetic fields can affect scalar cosmological perturbations
whose evolution is described in the conformally Newtonian gauge and within the
tight coupling approximation. The magnetized curvature perturbations present
after matter radiation equality (and prior to decoupling) are computed in terms
of an appropriate transfer matrix allowing a general estimate of the
Sachs-Wolfe plateau. From the observation that CMB initial conditions should be
(predominantly) adiabatic, the contribution of the magnetic field intensity can
be constrained.


title: X-ray spectra of sources in the 13H XMM-Newton / Chandra deep field

abstract:
  We present the X-ray spectra of 86 optically-identified sources in the 13H
XMM-Newton/Chandra deep field which have >70 X-ray counts. The sample consists
of 50 broad line AGN, 25 narrow emission line galaxies, 6 absorption line
galaxies, and 5 Galactic stars. The majority (42/50) of the broad line AGN have
X-ray spectra which are consistent with a power law shape. They have a mean
photon index of Gamma = 2.0 +- 0.1 and an intrinsic dispersion sigma = 0.4 +-
0.1. Five BLAGN show a deficit of soft X-rays, indicating absorption.
Significant absorption is more common in the narrow emission line galaxies
(13/25) and absorption line galaxies (2/6) than in the broad line AGN (5/50),
but is not universal in any of these classes of object. The majority of the 20
absorbed sources have X-ray spectra consistent with a simple cold photoelectric
absorber, but 6/20 require more complex models with either an additional
component of soft X-ray emitting plasma, or an ionised absorber. Of the 16
galaxies which do not show evidence for X-ray absorption, only 2 objects are
likely to be powered by star formation, and both have 2-10 keV X-ray
luminosities of <= 10^40 cgs. The X-ray emission in the other 14 unabsorbed
NELGs and galaxies is most likely powered by AGN, which are not detected in the
optical because they are outshone by their luminous host galaxies. The Galactic
stars show multi-temperature thermal spectra which peak between 0.5 and 1 keV.
Star/AGN discrimination is possible for 4 of the 5 stars solely from their
X-ray spectra.


title: The Interpretation and Implication of the Afterglow of GRB 060218

abstract:
  The nearby GRB 060216/SN 2006aj was an extremely long, weak and very soft
GRB. It was peculiar in many aspects. We show here that the X-ray,
ultraviolet/optical and radio afterglow of GRB 060218 have to be attributed to
different physical processes arising from different emission regions. From the
several components in this burst's afterglow only the radio afterglow can be
interpreted in terms of the common external shock model. We infer from the
radio that the blast wave's kinetic energy was $\sim 10^{50}$ erg and the
circumburst matter had a constant rather than a wind profile. The lack of a
"jet break" up to 22 days implies that the outflow was wide $\theta_j >1$. Even
though the late X-ray afterglow decays normally it cannot result from an
external shock because of its very steep spectrum. Furthermore, the implied
kinetic energy would have produced far too much radio. We suggest that this
X-ray afterglow could be attributed to a continued activity of the central
engine that within the collapsar scenario could arise from fall-back accretion.
"Central engine afterglow" may be common in under-luminous GRBs where the
kinetic energy of the blast wave is small and the external shock does not
dominate over this component. Such under-luminous GRBs might be very common but
they are rarely recorded because they can be detected only from short
distances.


title:
On the Environmental Dependence of Galaxy Properties Established by the
  Initial Cosmological Conditions

abstract:
  We study theoretically how the initial cosmological conditions establish the
dependence of galaxy properties on the environment. First, we adopt the linear
tidal torque theory according to which the angular momentum of a proto-galaxy
is generated at first order by the misalignment between the proto-galaxy
inertia tensor and the local tidal tensor. Then, we quantify analytically the
degree of the misalignment between the two tensors, and show quantitatively
that it increases as the density of the environment decreases. It implies that
the proto-galaxies forming in the lower density regions should end up with
having higher angular momentum than those in the higher density regions, which
is consistent with recent numerical finding that the void and field galaxies
have higher spin parameters than the cluster galaxies. Since the galaxy angular
momentum plays a role of developing a disk-like structure and hindering the
star-formation, our theoretical insight provides an answer to such fundamental
observational question as why the large void galaxies have young stellar
populations and high specific star formation rate, which was not explained by
the previous morphology-density relation.


title: The Fate of Discs around Massive Stars in Young Clusters

abstract:
  AIMS: The aim of this work is to understand whether there is a difference in
the dispersion of discs around stars in high-density young stellar clusters
like the Orion Nebula Cluster (ONC) according to the mass of the star.
  METHODS: Two types of simulations were combined -- N-body simulations of the
dynamics of the stars in the ONC and mass loss results from simulations of
star-disc encounters, where the disc mass loss of all stars is determined as a
function of time.
  RESULTS: We find that in the Trapezium, the discs around high-mass stars are
dispersed much more quickly and to a larger degree by their gravitational
interaction than for intermediate-mass stars. This is consistent with the very
recent observations of IC 348, where a higher disc frequency was found around
solar mass stars than for more massive stars, suggesting that this might be a
general trend in large young stellar clusters.


title:
A test on external Compton models for $\gamma$-ray active galactic
  nuclei

abstract:
  There is clear evidence that the $\gamma$-ray emission from active galactic
nuclei (AGNs) is attributed to the inverse Compton scatterings in the
relativistic blobs near the massive black holes. If the soft seed photons are
from the regions outside the blobs, a linear relation between $(\nu
F_{\nu,\gamma}/\nu F_{\nu, \rm syn} u^{*})^{1/(1+\alpha)}$ and Doppler factor
$\delta$ is expected, where $\nu F_{\nu,\gamma}$ and $\nu F_{\nu, \rm syn}$ are
monochromatic $\gamma$-ray and synchrotron fluxes, respectively, and $u^{*}$ is
the energy density of soft seed photons \citep{D97}. We estimate the soft
photon energy density in the relativistic blobs contributed by the broad line
region (BLRs) in these $\gamma$-ray AGNs using their broad-line emission data.
The Doppler factors $\delta$ are derived from their radio core and X-ray
emission data, based on the assumption that the X-ray emission is produced
through synchrotron self-Compton (SSC) scatterings. We find two nearly linear
correlations: $(\nu F_{\nu,\gamma}/\nu F_{\rm opt} u^{*})^{1/(1+\alpha)}
\propto \delta^{1.09}$, and $(\nu F_{\nu,\gamma}/\nu F_{\rm IR}
u^{*})^{1/(1+\alpha)} \propto \delta^{1.20}$, which are roughly consistent with
the linear correlation predicted by the theoretical model for external Compton
scatterings. Our results imply that the soft seed photons are dominantly from
the BLRs in these $\gamma$-ray AGNs.


title: HI content in galaxies in loose groups

abstract:
  Gas deficiency in cluster spirals is well known and ram-pressure stripping is
considered the main gas removal mechanism. In some compact groups too gas
deficiency is reported. However, gas deficiency in loose groups is not yet well
established. Lower dispersion of the member velocities and the lower density of
the intra-group medium in small loose groups favour tidal stripping as the main
gas removal process in them. Recent releases of data from HI Parkes all sky
survey (HIPASS) and catalogues of nearby loose groups with associated diffuse
X-ray emission have allowed us to test this notion. In this paper, we address
the following questions: (a) do galaxies in groups with diffuse X-ray emission
statistically have lower gas content compared to the ones in groups without
diffuse X-ray emission? (b) does HI deficiency vary with the X-ray luminosity
of the loose group in a systematic way? We find that (a) galaxies in groups
with diffuse X-ray emission, on average, are HI deficient, and have lost more
gas compared to those in groups without X-ray emission; the later are found not
to have significant HI deficiency; (b) no systematic dependence of the HI
deficiency with X-ray luminosity is found. Ram pressure assisted tidal
stripping and evaporation by thermal conduction are the two possible mechanisms
to account for this excess gas loss.


title: The sweeping rate in diffusion-mediated reactions on dust grain surfaces

abstract:
  A prominent chemical reaction in interstellar clouds is the formation of
molecular hydrogen by recombination, which essentially takes place on dust
grain surfaces. Analytical approaches to model such a system have hitherto
neglected the spatial aspects of the problem by employing a simplistic version
of the sweeping rate of reactants. We show how these aspects can be accounted
for by a consistent definition of the sweeping rate, and calculate it exactly
for a spherical grain. Two regimes can be identified: Small grains, on which
two reactants almost surely meet, and large grains, where this is very
unlikely. We compare the true sweeping rate to the conventional approximation
and find a characteristic reduction in both regimes, most pronounced for large
grains. These effects can be understood heuristically using known results from
the analysis of two-dimensional random walks. We finally examine the influence
of using the true sweeping rate in the calculation of the efficiency of
hydrogen recombination: For fixed temperature, the efficiency can be reduced
considerably, and relative to that, small grains gain in importance, but the
temperature window in which recombination is efficient is not changed
substantially.


title:
Comment on ``General Relativity Resolves Galactic Rotation Without
  Exotic Dark Matter'' by F.I. Cooperstock & S. Tieu

abstract:
  The general relativistic model of Cooperstock & Tieu, which attempts to fit
rotation curves of spiral galaxies without invoking dark matter, is tested
empirically using observations of the Milky Way. In particular, predictions for
the mass density in the solar neighbourhood and the vertical density
distribution at the position of the Sun are compared with observations. It is
shown that the model of Cooperstock & Tieu, which was so constructed that it
gives an excellent fit of the observed rotation curve, singularly fails to
reproduce the observed local mass density and the vertical density profile of
the Milky Way.