title: Inhomogeneous models of interacting dark matter and dark energy

abstract:
  We derive and analyze a class of spherically symmetric cosmological models
whose source is an interactive mixture of inhomogeneous cold dark matter (DM)
and a generic homogeneous dark energy (DE) fluid. If the DE fluid corresponds
to a quintessense scalar field, the interaction term can be associated with a
well motivated non--minimal coupling to the DM component. By constructing a
suitable volume average of the DM component we obtain a Friedman evolution
equation relating this average density with an average Hubble scalar, with the
DE component playing the role of a repulsive and time-dependent $\Lambda$ term.
Once we select an ``equation of state'' linking the energy density ($\mu$) and
pressure ($p$) of the DE fluid, as well as a free function governing the radial
dependence, the models become fully determinate and can be applied to known
specific DE sources, such as quintessense scalar fields or tachyonic fluids.
Considering the simple equation of state $p= (\gamma-1) \mu$ with $0\leq\gamma
<2/3$, we show that the free parameters and boundary conditions can be selected
for an adequate description of a local DM overdensity evolving in a suitable
cosmic background that accurately fits current observational data. While a DE
dominated scenario emerges in the asymptotic future, with total $\Omega$ and
$q$ tending respectively to 1 and -1/2 for all cosmic observers, the effects of
inhomogeneity and anisotropy yield different local behavior and evolution rates
for these parameters in the local overdense region. We suggest that the models
presented can be directly applied to explore the effects of various DE
formalisms on local DM cosmological inhomogeneities.


title: The dark halo of the main lens galaxy in QSO 0957+561

abstract:
  We present an analysis of infrared/optical/ultraviolet spectra of the two
images of the first gravitationally lensed quasar Q0957+561A, B. The Hubble
Space Telescope observations of Q0957+561A and Q0957+561B are separated in time
by the known time delay in this system, so we can directly deduce the flux
ratios. These flux ratios of images lead to important information on the dark
halo of the main lens galaxy (a giant elliptical at redshift z = 0.36). Our
measurements for the continuum are in good agreement with extinction in the
elliptical galaxy and a small fraction of mass in collapsed objects (no need
for gravitational microlensing). From the continuum and emission line ratios,
we also show evidence in favour of the existence of a network of compact dusty
clouds.


title: Number ratios of young stellar objects in embedded clusters

abstract:
  Embedded clusters usually contain young stellar objects in different
evolutionary stages. We investigate number ratios of objects in these classes
in the star-forming regions rho Ophiuchi, Serpens, Taurus, Chamaeleon I, NGC
7129, IC 1396A, and IC 348. They are compared to the temporal evolution of
young stars in numerical simulations of gravoturbulent fragmentation in order
to constrain the models and to possibly determine the evolutionary stage of the
clusters. It turns out that Serpens is the youngest, and IC 348 the most
evolved cluster, although the time when the observations are best represented
varies strongly depending on the model. Furthermore, we find an inverse
correlation of the star formation efficiency (SFE) of the models with the Mach
number. However, the observational SFE values cannot be reproduced by the
current isothermal models. This argues for models that take into account
protostellar feedback processes and/or the effects of magnetic fields.


title: Neutrino statistics and big bang nucleosynthesis

abstract:
  Neutrinos may possibly violate the spin-statistics theorem, and hence obey
Bose statistics or mixed statistics despite having spin half. We find the
generalized equilibrium distribution function of neutrinos which depends on a
single fermi-bose parameter, \kappa, and interpolates continuously between the
bosonic and fermionic distributions when \kappa changes from -1 to +1. We
consider modification of the Big Bang Nucleosynthesis (BBN) in the presence of
bosonic or partly bosonic neutrinos. For pure bosonic neutrinos the abundances
change (in comparison with the usual Fermi-Dirac case) by -3.2% for 4He (which
is equivalent to a decrease of the effective number of neutrinos by \Delta
N_\nu = - 0.6), +2.6% for 2H and -7% for 7Li. These changes provide a better
fit to the BBN data. Future BBN studies will be able to constrain the
fermi-bose parameter to \kappa > 0.5, if no deviation from fermionic nature of
neutrinos is found. We also evaluate the sensitivity of future CMB and LSS
observations to the fermi-bose parameter.


title:
Discovery of 1323 s pulsations from RX J0103.6-7201: the longest period
  X-ray pulsar in the SMC

abstract:
  XMM-Newton archival observations of the Be/X-ray binary candidate RX
J0103.6-7201 revealed pulsations with a period of ~1323 s. This makes RX
J0103.6-7201 the X-ray pulsar with the longest period known in the Small
Magellanic Cloud (SMC). More than 150 X-ray observations of RX J0103.6-7201 by
ROSAT, Chandra and XMM-Newton show flux variations by a factor of 50 on time
scales of days to years. Using the accurate positions obtained from ACIS-I
images the optical counterpart is identified with a V = 14.6 mag emission line
star. EPIC spectra of RX J0103.6-7201 above 1 keV are consistent with an
absorbed power-law with column density between (6-9)x10^21 cm^-2, except during
one observation when an extraordinary high value of 1.1x10^23 cm^-2 was
measured which strongly attenuated the power-law emission below 3 keV. A soft
excess between 0.5 and 1.0 keV is evident in the spectra which becomes best
visible in the highly absorbed spectrum. The soft component can be reproduced
by a thermal plasma emission model with its luminosity strongly correlated with
the total intrinsic source luminosity. Including results from three other SMC
Be/X-ray binaries extends the linear correlation over three orders of magnitude
in source intensity, strongly suggesting that the same mechanism is responsible
for the generation of the soft emission.


title: Metallicity dependence of the Blazhko effect

abstract:
  The microlensing surveys, such as OGLE or MACHO, have led to the discovery of
thousands of RR Lyrae stars in the Galactic Bulge and in the Magellanic Clouds,
allowing for detailed investigation of these stars, specially the still
mysterious Blazhko phenomenon. Higher incidence rate of Blazhko (BL) variables
in the more metal-rich Galactic Bulge than in the LMC, suggests that occurance
of Blazhko effect correlates with metallicity (Moskalik and Poretti 2003). To
investigate this problem, we calibrate the photometric method of determining
the metallicity of the RRab star (Kovacs and Zsoldos 1995) to the I-band and
apply it to the OGLE Galactic Bulge and LMC data. In both systems,
metallicities of non Blazhko and Blazhko variables are close to each other. The
LMC Blazhko pulsators prefer slightly lower metallicities. The different
metallicities of the Galactic Bulge and the LMC, can't explain the observed
incidence rates.
  As a by-product of our metallicity estimates, we investigate the
luminosity-metallicity relation, finding a steep dependence of the luminosity
on [Fe/H]


title: Metallicity Estimates for Old Star Clusters in M33

abstract:
  Using the theoretical stellar population synthesis models of BC96, Kong et
al. (2003) showed that some BATC colors and color indices could be used to
disentangle the age and metallicity effect. They found that there is a very
good relation between the flux ratio of L_{8510}/L_{9170} and the metallicity
for stellar populations older than 1 Gyr. In this paper, based on the Kong et
al. results and on the multicolor spectrophotometry of Ma et al. (2001,
2002a,b,c), we estimate the metallicities of 31 old star clusters in the nearby
spiral galaxy M33, 23 of which are ``true'' globular clusters. The results show
that most of these old clusters are metal poor. We also find that the ages and
metal abundance for these old star clusters of M33 do not vary with deprojected
radial position.


title: Color and Metallicity Distributions of M81 Globular Clusters

abstract:
  In this paper we present catalogs of photometric and spectroscopic data for
M81 globular clusters (GCs). The catalogs include B- and V- photometric and
reddening data of 95 GCs, and spectroscopic metallicities of 40 GCs in M81.
Using these data, we make some statistical correlations. The results show that
the distributions of intrinsic B and V colors and metallicities are bimodal,
with metallicity peaks at [Fe/H]=-1.45 and -0.53, respectively as has been
demonstrated for our Milky Way and M31. The relation between spectroscopic
metallicity and intrinsic B and V color also exists as it does for the Milky
Way and M31.


title: A Model for Multidimensional Delayed Detonations in SN Ia Explosions

abstract:
  We show that a flame tracking/capturing scheme originally developed for
deflagration fronts can be used to model thermonuclear detonations in
multidimensional explosion simulations of type Ia supernovae. After testing the
accuracy of the front model, we present a set of two-dimensional simulations of
delayed detonations with a physically motivated off-center
deflagration-detonation-transition point. Furthermore, we demonstrate the
ability of the front model to reproduce the full range of possible interactions
of the detonation with clumps of burned material. This feature is crucial for
assessing the viability of the delayed detonation scenario.


title:
Submillimetre photometry of X-ray absorbed QSOs: their formation and
  evolutionary status

abstract:
  We present an analysis of the submillimetre/X-ray properties of 19 X-ray
absorbed, Compton-thin quasi-stellar objects (QSOs) selected to have
luminosities and redshifts which represent the peak of cosmic QSO activity.
i.e. ~L* objects at 1<z<3. Of these, we present new data for 11 objects not
previously observed at submillimetre wavelengths and additional data for a
further 3. The detection rate is 42 per cent, much higher than typically
reported for samples of QSOs. Detection statistics show (at the 3-4 sigma
level) that this sample of absorbed QSOs has a higher submillimetre output than
a matched sample of unabsorbed QSOs. We argue that the far-infrared luminosity
is produced by massive star formation. In this case, the correlation found
between far-infrared luminosity and redshift can be interpreted as cosmological
evolution of the star-formation rate in the QSO host galaxies. Since the
submillimetre luminous phase is confined to z>1.5, the high star formation
rates are consistent with a scenario in which the QSOs evolve to become local
luminous elliptical galaxies.
  Combining these results with previously published data for X-ray unabsorbed
QSOs and submillimetre-selected galaxies we propose the following evolutionary
sequence: the forming galaxy is initially far-infrared luminous but X-ray weak
similar to the sources discovered by the Submillimetre Common-User Bolometer
Array; as the black hole and spheroid grow with time a point is reached when
the central QSO becomes powerful enough to terminate the star formation and
eject the bulk of the fuel supply (the Compton-thin absorbed QSO phase); this
transition is followed by a period of unobscured QSO activity which
subsequently declines to leave a quiescent spheroidal galaxy.


title: New insights on the AU-scale circumstellar structure of FU Orionis

abstract:
  We report new near-infrared, long-baseline interferometric observations at
the AU scale of the pre-main-sequence star FU Orionis with the PTI, IOTA and
VLTI interferometers. This young stellar object has been observed on 42 nights
over a period of 6 years from 1998 to 2003. We have obtained 287 independent
measurements of the fringe visibility with 6 different baselines ranging from
20 to 110 meters in length, in the H and K bands. Our extensive (u,v)-plane
coverage, coupled with the published spectral energy distribution data, allows
us to test the accretion disk scenario. We find that the most probable
explanation for these observations is that FU Ori hosts an active accretion
disk whose temperature law is consistent with standard models. We are able to
constrain the geometry of the disk, including an inclination of 55 deg and a
position angle of 47 deg. In addition, a 10 percent peak-to-peak oscillation is
detected in the data (at the two-sigma level) from the longest baselines, which
we interpret as a possible disk hot-spot or companion. However, the oscillation
in our best data set is best explained with an unresolved spot located at a
projected distance of 10 AU at the 130 deg position angle and with a magnitude
difference of DeltaK = 3.9 and DeltaH = 3.6 mag moving away from the center at
a rate of 1.2 AU/yr. we propose to interpret this spot as the signature of a
companion of the central FU Ori system on an extremely eccentric orbit. We
speculate that the close encounter of this putative companion and the central
star could be the explanation of the initial photometric rise of the luminosity
of this object.


title:
Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope
  Imaging. III: Measurement for Ursa Minor

abstract:
  This article presents a measurement of the proper motion of the Ursa Minor
dwarf spheroidal galaxy determined from images taken with the Hubble Space
Telescope in two distinct fields.


title: Scintillation Response of Liquid Xenon to Low Energy Nuclear Recoils

abstract:
  Liquid Xenon (LXe) is expected to be an excellent target and detector medium
to search for dark matter in the form of Weakly Interacting Massive Particles
(WIMPs). Knowledge of LXe ionization and scintillation response to low energy
nuclear recoils expected from the scattering of WIMPs by Xe nuclei is important
for determining the sensitivity of LXe direct detection experiments. Here we
report on new measurements of the scintillation yield of Xe recoils with
kinetic energy as low as 10 keV. The dependence of the scintillation yield on
applied electric field was also measured in the range of 0 to 4 kV/cm. Results
are in good agreement with recent theoretical predictions that take into
account the effect of biexcitonic collisions in addition to the nuclear
quenching effect.


title: Dark matter from extra dimensions

abstract:
  In brane-world models with low tension, massive branons are natural
candidates for dark matter. The phenomenology of these WIMP-like particles is
completely determined by their mass, the brane tension and, in the case of
effects due to radiative corrections, by the cutoff setting the scale of
validity of the branon effective theory. In this paper, we review the main
constraints on branon physics coming from colliders, astrophysics and
cosmological observations, and include more recent limits obtained from
electroweak precision measurements.


title: The XMM-Newton view of Mrk3 and IXO30

abstract:
  We present the analysis of the XMM-Newton EPIC pn spectrum of the Seyfert 2
galaxy, Mrk3. We confirm that the source is dominated by a pure Compton
reflection component and an iron K$\alpha$ line, both produced as reflection
from a Compton-thick torus, likely responsible also for the large column
density which is pierced by the primary powerlaw only at high energies. A low
inclination angle and an iron underabundance, suggested by the amount of
reflection and the depth of the iron edge, are consistent with the iron
K$\alpha$ line EW with respect to the Compton reflection component. Moreover,
the iron line width, if interpreted in terms of Doppler broadening due to the
Keplerian rotation of the torus, puts an estimate to the inner radius of the
latter, $r=0.6^{+1.3}_{-0.3} \sin^2{i}$ pc. Finally, two different photoionised
reflectors are needed to take into account a large number of soft X-ray
emission lines from N, O, Ne, Mg, Si, Fe L and the FeXXV emission line. RGS
spectra show that the soft X-ray spectrum is dominated by emission lines, while
the underlying continuum is best fitted by an unabsorbed powerlaw with the same
photon index of the primary continuum, produced as reflection by a photoionised
material with a column density of a few $10^{22}$ cm$^{-2}$. We also present
the first X-ray spectrum of ROSAT source IXO30, which shows a huge iron line
and is well represented either by an absorbed powerlaw or bremsstrahlung
emission. Its spectral properties point to a likely identification in terms of
a weak Galactic Cataclysmic Variable, but the lack of any optical counterpart
precludes excluding other possibilities, like an ULX at the distance of Mrk3.


title: A Short and Personal History of the Spitzer Space Telescope

abstract:
  The Spitzer Space Telescope, born as the Shuttle Infrared Telescope Facility
(SIRTF) and later the Space Infrared Telescope Facility (still SIRTF), was
under discussion and development within NASA and the scientific community for
more than 30 years prior to its launch in 2003. This brief history chronicles a
few of the highlights and the lowlights of those 30 years from the authors
personal perspective. A much more comprehensive history of SIRTF/Spitzer has
been written by George Rieke (2006).


title: Climatic and Biogeochemical Effects of a Galactic Gamma-Ray Burst

abstract:
  It is likely that one or more gamma-ray bursts within our galaxy have
strongly irradiated the Earth in the last Gy. This produces significant
atmospheric ionization and dissociation, resulting in ozone depletion and
DNA-damaging ultraviolet solar flux reaching the surface for up to a decade.
Here we show the first detailed computation of two other significant effects.
Visible opacity of NO2 is sufficient to reduce solar energy at the surface up
to a few percent, with the greatest effect at the poles, which may be
sufficient to initiate glaciation. Rainout of dilute nitric acid is could have
been important for a burst nearer than our conservative nearest burst. These
results support the hypothesis that the characteristics of the late Ordovician
mass extinction are consistent with GRB initiation.

categories: astro-ph physics.ao-ph physics.geo-ph physics.space-ph q-bio.PE


title:
The Araucaria Project. Near-Infrared Photometry of Cepheid Variables in
  the Sculptor Galaxy NGC 300

abstract:
  We have obtained deep near-infrared images in J and K filters of three fields
in the Sculptor galaxy NGC 300 with the ESO VLT and ISAAC camera. For 16
Cepheid variables in these fields, we have determined J and K magnitudes at two
different epochs, and have derived their mean magnitudes in these bands. The
slopes of the resulting period-luminosity relations are in very good agreement
with the slopes of these relations measured in the LMC by Persson et al.
Fitting the LMC slopes to our data, we have derived distance moduli in J and K.
Using these values together with the values derived in the optical V and I
bands in our previous work, we have determined an improved total reddening for
NGC 300 of E(B-V)=0.096 +/- 0.006 mag, which yields extremely consistent values
for the absorption-corrected distance modulus of the galaxy from VIJK bands.
Our distance result for NGC 300 from this combined optical/near infrared
Cepheid study is (m-M)_0 = 26.37 +/- 0.04 (random) +/- 0.03 (systematic) mag
and is tied to an adopted true LMC distance modulus of 18.50 mag. Both random
and systematic uncertainties are dominated by photometric errors, while errors
due to reddening, metallicity effects and crowding are less important. Our
distance determination is consistent with the earlier result from near-infrared
(H-band) photometry of two Cepheids in NGC 300 by Madore et al., but far more
accurate. Our distance value also agrees with the HST Key Project result of
Freedman et al., and with the recent distance estimate for NGC 300 from Butler
et al. from the TRGB I-band magnitude when our improved reddening is used to
calculate the absorption corrections. Our distance results from the different
optical and near-infrared bands indicate that the reddening law in NGC 300 must
be very similar to the Galactic one.


title:
Exploring Halo Substructure with Giant Stars. VI. Extended Distributions
  of Giant Stars Around the Carina Dwarf Spheroidal Galaxy -- How Reliable Are
  They?

abstract:
  The question of the existence of active tidal disruption around various dSph
galaxies remains controversial. That debate often centers on the nature (bound
vs. unbound) of extended populations of stars. However, the more fundamental
issue of the very existence of the extended populations is still contentious.
We present an evaluation of the debate centering on one particular dSph,
Carina, for which claims both for and against the existence of stars beyond the
King radius have been made. Our review includes an examination of all previous
studies bearing on the Carina radial profile and shows that the survey method
which achieves the highest detected dSph signal-to-background in the outer
parts of the galaxy is the Washington M, T2 + DDO51 (MTD) filter approach from
Paper II in this series. We then address statistical methods used to evaluate
the reliability of MTD surveys in the presence of photometric errors and for
which a new, a posteriori statistical analysis methodology is provided.
Finally, these statistical methods are tested by new spectroscopy of stars in
the MTD-selected Carina candidate sample. Of 74 candidate giants with follow-up
spectroscopy, the MTD technique identified 61 new Carina members, including 8
stars outside the King radius. From a sample of 29 stars not initially
identified as candidate Carina giants but that lie just outside of our
selection criteria, 12 have radial velocities consistent with membership,
including 5 extratidal stars. Carina is shown to have an extended population of
giant stars extending to a major axis radius of 40' (1.44x the nominal King
radius).


title: Observational Studies of Early-type Binary Stars: MP Centauri

abstract:
  We present photometric and spectroscopic data on the early-type binary MP
Centauri. The photometric data are analyzed simultaneously with radial
velocities to derive preliminary absolute dimensions for the binary components.
Analysis of the spectra shows that the stars rotate synchronously and that the
line of sight to the system crosses two kinematically sharp and well-separated
interstellar reddening sources. It is shown that MP Cen consists of a B3
primary with M_1 = 11.4 +/- 0.4 M_sun, R_1 = 7.7 +/- 0.1 R_sun and a
lobe-filling B6-B7 secondary with M_2 = 4.4 +/- 0.2 M_sun, R_2 = 6.6 +/- 0.1
R_sun


title:
Numeric simulation of relativistic stellar core collapse and the
  formation of Reissner-Nordstrom space-times

abstract:
  The time evolution of a set of 22 Mo unstable charged stars that collapse is
computed integrating the Einstein-Maxwell equations. The model simulate the
collapse of an spherical star that had exhausted its nuclear fuel and have or
acquires a net electric charge in its core while collapsing. When the charge to
mass ratio is Q/M >= 1 the star do not collapse and spreads. On the other hand,
it is observed a different physical behavior with a charge to mass ratio 1 > Q/
M > 0.1. In this case, the collapsing matter forms a bubble enclosing a lower
density core. We discuss an immediate astrophysical consequence of these
results that is a more efficient neutrino trapping during the stellar collapse
and an alternative mechanism for powerful supernova explosions. The outer
space-time of the star is the Reissner-Nordstrom solution that match smoothly
with our interior numerical solution, thus the collapsing models forms
Reissner-Nordstrom black holes.


title:
GRB jets inside and outside the star: precursors and cosmological
  implications

abstract:
  After many years of speculation, recent observations have confirmed the
association of gamma-ray bursts with core-collapse supernova explosions from
massive stars. This association carries with it important consequences. The
burst relativistic jet has to propagate through the cold dense stellar material
before it reaches the transparency radius and the burst photons are produced.
This propagation is likely to affect the initial properties of the jet, shaping
it and changing its energy composition. The variability injected at the base of
the jet is also likely to be erased by the jet-star interaction. Despite this,
GRBs seem to have remarkably predictable properties once the radiative phase
sets in, as emphasized by the recent discovery of several tight correlation
between spectral, geometric and energetic properties of the jet. In this
contribution we discuss the jet interaction with the star, emphasizing its
time-dependent properties and the resulting energy distribution. We finally
emphasize the surprising predictability of jet and radiation properties outside
the star and underline its implication for standardizing the GRB candle.


title: Lyman Break Galaxies at z = 4 - 6 in cosmological SPH Simulations

abstract:
  We perform a spectrophotometric analysis of galaxies at redshifts z = 4 - 6
in cosmological SPH simulations of a Lambda CDM universe. Our models include
radiative cooling and heating by a uniform UV background, star formation,
supernova feedback, and a phenomenological model for galactic winds. Analysing
a series of simulations of varying boxsize and particle number allows us to
isolate the impact of numerical resolution on our results. Specifically, we
determine the luminosity functions in B, V, R, i', and z' filters, and compare
the results with observed galaxy surveys done with the Subaru telescope and the
Hubble Space Telescope. We find that the simulated galaxies have UV colours
consistent with observations and fall in the expected region of the
colour-colour diagrams used by the Subaru group. Assuming a uniform extinction
of E(B-V) = 0.15, we also find reasonable agreement between simulations and
observations in the space density of UV bright galaxies at z = 3 - 6, down to
the magnitude limit of each survey. For the same moderate extinction level of
E(B-V) ~ 0.15, the simulated luminosity functions match observational data, but
have a steep faint-end slope with alpha ~ -2.0. We discuss the implications of
the steep faint-end slope found in the simulations.


title:
Discovery of a Large ~200 kpc Gaseous Nebula at z=2.7 with the Spitzer
  Space Telescope

abstract:
  We report the discovery of a very large, spatially extended Ly alpha
-emitting nebula at z=2.656 associated with a luminous mid-infrared source. The
bright mid-infrared source (F(24um)=0.86 mJy) was first detected in
observations made using the Spitzer Space Telescope. Existing broad-band
imaging data from the NOAO Deep Wide-Field Survey revealed the mid-infrared
source to be associated with a diffuse, spatially extended, optical counterpart
in the Bw band. Spectroscopy and further imaging of this target reveals that
the optical source is an almost purely line-emitting nebula with little, if
any, detectable diffuse continuum emission. The Lya nebula has a luminosity of
L[Lya] ~ 1.7e44 erg/s and an extent of at least 20 arcsec (160 kpc). Its
central ~8 arcsec shows an ordered, monotonic velocity profile; interpreted as
rotation, this region encloses a mass M = 6e12 Msun. Several sources lie within
the nebula. The central region of the nebula shows narrow (~365 km/s) emission
lines of CIV and HeII. The mid-infrared source is a compact object lying within
the nebula, but offset from the center by a projected distance of ~2.5 arcsec
(20 kpc), and likely to be an enshrouded AGN. A young star-forming galaxy lies
near the northern end of the nebula. We suggest that the nebula is a site of
recent multiple galaxy and AGN formation, with the spatial distribution of
galaxies within the nebula perhaps tracking the formation history of the
system.


title: Physical conditions in the Homunculus

abstract:
  Conditions within the Homunculus nebula around Eta Car are determined by many
of the same physical processes that occur in molecular clouds in the
interstellar medium. But there is one major exception -- we know when the
ejection occurred and something about its composition and initial state. The
gas was warm, ionized, and dust-free when it was located within the star's
atmosphere and it is currently cold, molecular, and dusty. It undertook this
transformation in a bit over 150 years. It offers a laboratory for the study of
physical processes in a well-constrained environment. We derive a
photoionization model of the Homunculus nebula that reproduces many of its
observed properties. We conclude by outlining how observations of the
Homunculus could address basic problems in the physics of the interstellar
medium.


title:
Discovery of Optical Emission in the Hotspots of Three 3CR Quasars:
  High-Energy Particle Acceleration in Powerful Radio Hotspots

abstract:
  Archival Hubble Space Telescope WFPC2 images were used to search for optical
emission associated with the radio jets of a number of luminous quasars. From
this search, we report new optical hotspot detections in the well-known blazar
3C~454.3 and the lobe-dominated quasars 3C~275.1 and 3C~336. We also find
optical emission in the vicinity of the hotspot in 3C~208, but believe this is
a chance alignment. Optical emission from the arcsecond-scale jet in 3C~454.3
is also detected. Multi-frequency archival radio data from the VLA and MERLIN
are analyzed, and the synchrotron spectra of these high-power hotspots are
presented. We estimate that their break frequencies are in the range of
$10^{10}-10^{11}$ Hz, with large uncertainties due to the wide gap in frequency
coverage between the radio and optical bands. We also calculate their
equipartition magnetic fields, and find that the anti-correlation between break
frequency and magnetic field found by Brunetti et al. for lower power hotspots
extends to these high power hotspots. This supports their model of hot-spots
based on shock acceleration and synchrotron losses.


title: The Shape of the Inner Rim in Proto-Planetary Disks

abstract:
  This paper discusses the properties of the inner puffed-up rim which forms in
circumstellar disks when dust evaporates. We argue that the rim shape is
controlled by a fundamental property of circumstellar disks, namely their very
large vertical density gradient, through the dependence of grain evaporation
temperature on gas density. As a result, the bright side of the rim is
"curved", rather than "vertical", as expected when a constant evaporation
temperature is assumed. We have computed a number of rim models, which take
into account this effect in a self-consistent way. The results show that the
curved rim (as the vertical rim) emits most of its radiation in the near and
mid-IR, and provides a simple explanation to the observed values of the near-IR
excess (the "3 micron bump" of Herbig Ae stars). Contrary to the vertical rim,
for curved rims the near-IR excess does not depend much on the inclination,
being maximum for face-on objects. We have then computed synthetic images of
the curved rim seen under different inclinations; face-on rims are seen as
bright, centrally symmetric rings on the sky; increasing the inclination, the
rim takes an elliptical shape, with one side brighter than the other.


title:
Electron-Ion Temperature Equilibration at Collisionless Shocks in
  Supernova Remnants

abstract:
  The topic of this review is the current state of our knowledge about the
degree of initial equilibration between electrons, protons and ions at
supernova remnant (SNR) shocks. Specifically, the question has been raised as
to whether there is an inverse relationship between the shock velocity and the
equilibration similar to the relationship between equilibration and Alfven Mach
number seen in interplanetary shocks (Schwartz et al 1988). This review aims to
compile every method that has been used to measure the equilibration and every
SNR on which they have been tested. I review each method, its problems and
uncertainties and how those would effect the degree of equilibration (or
velocity) inferred. The final compilation of observed electron to proton
temperature ratios as a function of shock velocity gives an accurate,
conservative picture of the state of our knowledge and the avenues we need to
pursue to make progress in our understanding of the relation between the
velocity of a shock and the degree of equilibration.


title:
Direct Distances to Cepheids in the Large Magellanic Cloud: Evidence for
  a Universal Slope of the Period-Luminosity Relation up to Solar Abundance

abstract:
  We have applied the infrared surface brightness (ISB) technique to derive
distances to 13 Cepheids in the LMC which span a period range from 3 to 42
days. From the absolute magnitudes of the variables calculated from these
distances, we find that the LMC Cepheids define tight period-luminosity
relations in the V, I, W,
  J and K bands which agree exceedingly well with the corresponding Galactic PL
relations derived from the same technique, and are significantly steeper than
the LMC PL relations in these bands observed by the OGLE-II Project in V, I and
W, and by Persson et al. in J and K. We find that the tilt-corrected true
distance moduli of the LMC Cepheids show a significant dependence on period,
which hints at a systematic error in the ISB technique related to the period of
the stars. We identify as the most likely culprit the p-factor which converts
the radial into pulsational velocities; our data imply a much steeper period
dependence of the p-factor than previously thought, and we derive p=1.58
(+/-0.02) -0.15 (+/-0.05) logP as the best fit from our data, with a zero point
tied to the Milky Way open cluster Cepheids. Using this revised p-factor law,
the period dependence of the LMC Cepheid distance moduli disappears, and at the
same time the Milky Way and LMC PL relations agree among themselves, and with
the directly observed LMC PL relations, within the 1 sigma uncertainties. Our
main conclusion is that the previous, steeper Galactic PL relations were caused
by an erroneous calibration of the p-factor law, and that there is now evidence
that the slope of the Cepheid PL relation is independent of metallicity up to
solar metallicity, in both optical, and near-infrared bands.


title:
Detecting Clusters of Galaxies at High Redshift with the Spitzer Space
  Telescope

abstract:
  We present an infrared adaptation of the Cluster Red-Sequence method. We
modify the two filter technique of Gladders & Yee (2000) to identify clusters
based on their R-[3.6] color. We apply the technique to the 4 degree^2 Spitzer
First Look Survey and detect 123 clusters spanning the redshift range 0.09 < z
< 1.4. Our results demonstrate that the Spitzer Space Telescope will play an
important role in the discovery of large samples of high redshift galaxy
clusters.


title: Near-infrared imaging of 222 nearby Hdelta-strong galaxies from the SDSS

abstract:
  We present UFTI K-band imaging observations of 222 galaxies that are selected
from the Sloan Digital Sky Survey to have unusually strong Hdelta absorption
equivalent widths, W(Hd)>4A. Using GIM2D, the images are fit with
two-dimensional surface brightness models consisting of a simple disk and bulge
component to derive B/T, the fraction of luminosity in the bulge. We find that
the galaxies with weak or absent Halpha or [OII] emission (known as k+a
galaxies) are predominantly bulge-dominated (with a mode of B/T~0.6), while
galaxies with nebular emission (known as e[a] galaxies) are mostly
disk-dominated (B/T~0.1). The morphologies and (r-k) colours of most k+a
galaxies are inconsistent with the hypothesis that they result from the
truncation of star formation in normal, spiral galaxies. However, their (u-g)
and (r-k) colours, as well as their Hdelta line strengths, form a sequence that
is well matched by a model in which >5 per cent of the stellar mass has been
produced in a recent starburst. The lack of scatter in the dust-sensitive (r-k)
colours suggests that the unusual spectra of k+a galaxies are not due to the
effects of dust. The e(a) galaxies, on the other hand, have a colour
distribution that is distinct from the k+a population, and typical of normal or
dusty (tauV~2) spiral galaxies. We conclude that many e(a) galaxies are not
progenitors of k+a galaxies, but are a separate phenomenon. Both k+a and e(a)
galaxies reside in environments (characterized by the local density of galaxies
brighter than Mr=-20) that are typical of normal galaxies and that are
inconsistent with overdense regions like rich galaxy clusters.


title: Evolution of the 3.6 micron Cluster Luminosity Function

abstract:
  We have measured the 3.6 micron cluster luminosity function (LF) using a
sample of 123 galaxy clusters selected from the 4 degree^2 Spitzer First Look
Survey (FLS). The clusters were selected on the basis of their R - 3.6 micron
colors using the cluster red-sequence technique of Gladders & Yee (2000). The
binned LFs are well-fit by a Schechter function at all redshifts. However, we
note two interesting trends. Firstly, the evolution of Mstar with redshift is
consistent with models that form galaxies in a single-burst of star-formation
at z > 2.0, and evolve passively thereafter. Secondly, the faint-end slope of
the LF appears to become shallower at higher redshift. We conclude that the
most massive galaxies were formed in the cluster at high redshift (z > 2),
while lower-mass galaxies have subsequently been accreted from the field at
lower redshift (z ~ 0.5). These results are consistent with the ``downsizing''
picture seen in previous cluster studies using smaller samples.


title: White Dwarf Heating and Subsequent Cooling in Dwarf Nova Outbursts

abstract:
  We follow the time dependent thermal evolution of a white dwarf (WD)
undergoing sudden accretion in a dwarf nova outburst, using both simulations
and analytic estimates. The post-outburst lightcurve clearly separates into
early times when the WD flux is high, and late times when the flux is near the
quiescent level. The break between these two regimes, occurring at a time of
order the outburst duration, corresponds to a thermal diffusion wave reaching
the base of the freshly accreted layer. Our principal result is that long after
the outburst, the fractional flux perturbation about the quiescent flux decays
as a power law with time (and {\it not} as an exponential). We use this result
to construct a simple fitting formula that yields estimates for both the
quiescent flux and the accreted column, i.e. the total accreted mass divided by
WD surface area. The WD mass is not well constrained by the late time
lightcurve alone, but it can be inferred if the accreted mass is known from
observations. We compare our work with the well-studied outburst of WZ Sge,
finding that the cooling is well described by our model, giving an effective
temperature $T_{\rm eff}=14,500 {\rm K}$ and accreted column $\Delta
y\approx10^6 {\rm g cm^{-2}}$, in agreement with the modeling of Godon et al.
To reconcile this accreted column with the accreted mass inferred from the
bolometric accretion luminosity, a large WD mass $\gtrsim1.1M_\odot$ is needed.
Our power law result is a valuable tool for making quick estimates of the
outburst properties. We show that fitting the late time lightcurve with this
formula yields a predicted column within 20% of that estimated from our full
numerical calculations.


title:
New s-process path and its implication to 187Re-187Os
  nucleo-cosmochronometer

abstract:
  We study a new s-process path through an isomer of $^{186}$Re to improve a
$^{187}$Re-$^{187}$Os nucleo-cosmochronometer. The nucleus $^{187}$Re is
produced by this new path of
$^{185}$Re(n,$\gamma$)$^{186}$Re$^m$(n,$\gamma$)$^{187}$Re. We measure a ratio
of neutron capture cross-sections for the $^{185}$Re(n,$\gamma$)$^{186}$Re$^m$
and $^{185}$Re(n,$\gamma$)$^{186}$Re$^{gs}$ reactions at thermal neutron energy
because the ratio with the experimental uncertainty has not been reported.
Using an activation method with reactor neutrons, we obtain the ratio of
$R_{th}$ = 0.54 $\pm$ 0.11%. From this ratio we estimate the ratio of
Maxwellian averaged cross sections in a typical s-process environment at $kT$ =
30 keV with a help of the temperature dependence given in a statistical-model
calculation because the energy dependence of the isomer/ground ratio is smaller
than the absolute neutron capture cross-section. The ratio at $kT$=30 keV is
estimated to be $R_{st}$ = 1.3 $\pm$ 0.8%. We calculate the s-process
contribution from the new path in a steady-flow model. The additional abundance
of $^{187}$Re through this path is estimated to be $N_{s}$ = 0.56 $\pm$ 0.35%
relative to the abundance of $^{186}$Os. This additional increase of $^{187}$Re
does not make any remarkable change in the $^{187}$Re-$^{187}$Os chronometer
for an age estimate of a primitive meteorite, which has recently been found to
be affected strongly by a single supernova r-process episode.


title: Probing the Origins of Voids in the Distribution of Galaxies

abstract:
  If the voids that we see today in the distribution of galaxies existed at
recombination, they will leave an imprint on the cosmic microwave background
(CMB). On the other hand, if these voids formed much later, their effect on the
CMB will be negligible and will not be observed with the current generation of
experiments. In this paper presented at the 2004 Annual Scientific Meeting of
the Astronomical Society of Australia, we discuss our ongoing investigations
into voids of primordial origin. We show that if voids in the cold dark matter
distribution existed at the epoch of decoupling, they could contribute
significantly to the apparent rise in CMB power on small scales detected by the
Cosmic Background Imager (CBI) Deep Field. Here we present our improved method
for predicting the effects of primordial voids on the CMB in which we treat a
void as an external source in the cold dark matter (CDM) distribution employing
a Boltzmann solver. Our improved predictions include the effects of a
cosmological constant (Lambda) and acoustic oscillations generated by voids at
early times. We find that models with relatively large voids on the last
scattering surface predict too much CMB power in an Einstein--de Sitter
background cosmology but could be consistent with the current CMB observations
in a Lambda-CDM universe.


title: Two Windows on Acceleration and Gravitation: Dark Energy or New Gravity?

abstract:
  Small distortions in the observed shapes of distant galaxies, a cosmic shear
due to gravitational lensing, can be used to simultaneously determine the
distance-redshift relation, r(z), and the density contrast growth factor, g(z).
Both of these functions are sensitive probes of the acceleration. Their
simultaneous determination allows for a consistency test and provides
sensitivity to physics beyond the standard dark energy paradigm.


title: The HST Cosmos Project: Contribution from the Subaru Telescope

abstract:
  The Cosmic Evolution Survey (COSMOS) is a Hubble Space Telescope (HST)
treasury project.The COSMOS aims to perform a 2 square degree imaging survey of
an equatorial field in $I$(F814W) band, using the Advanced Camera for Surveys
(ACS). Such a wide field survey, combined with ground-based photometric and
spectroscopic data, is essential to understand the interplay between large
scale structure, evolution and formation of galaxies and dark matter. In 2004,
we have obtained high-quality, broad band images of the COSMOS field ($B, V,
r^\prime, i^\prime,$ and $ z^\prime$) using Suprime-Cam on the Subaru
Telescope, and we have started our new optical multi-band program, COSMOS-21 in
2005. Here, we present a brief summary of the current status of the COSMOS
project together with contributions from the Subaru Telescope. Our future
Subaru program, COSMOS-21, is also discussed briefly.


title: The SZ effect from cluster cavities

abstract:
  In this Letter we derive the SZ effect (SZE) observable in the direction of
the giant X-ray cavities found in the atmospheres of galaxy clusters. We
explore specifically the case of the cluster MS0735.6+7421. The SZE produced in
the cavities embedded in the cluster thermal atmosphere is of non-thermal
nature: it dominates the overall cluster SZE at the frequency x_{0,th} - at
which the thermal SZE from the cluster vanishes - and appears, at mm and sub-mm
frequencies, as a negative SZE located only in the regions of the intracluster
space occupied by the cavities. We show that SZ observations, combined with
X-ray and radio data, are able to shed light on the morphology, on the physical
structure, on the dynamics and the origin of these recently discovered
non-thermal features of galaxy clusters. These studies will be also relevant to
determine the impact of specific events of the nature of cavities on the use of
SZ and X-ray clusters as probes for cosmology and for the large scale structure
of the universe.


title:
The distance to Hydra and Centaurus from surface brightness
  fluctuations: Consequences for the Great Attractor model

abstract:
  We present I-band Surface Brightness Fluctuations (SBF) measurements for 16
early type galaxies (3 giants, 13 dwarfs) in the central region of the Hydra
cluster, based on deep photometric data in 7 fields obtained with VLT FORS1.
  From the SBF-distances to the galaxies in our sample we estimate the distance
of the Hydra cluster to be 41.2 +/- 1.4 Mpc ((m-M)=33.07 +/- 0.07 mag). Based
on an improved correction for fluctuations from undetected point sources, we
revise the SBF-distance to the Centaurus cluster from Mieske & Hilker (2003)
upwards by 10% to 45.3 +/- 2.0 Mpc ((m-M)=33.28 +/- 0.09 mag). The relative
distance modulus of the two clusters then is (m-M)_Cen - (m-M)_Hyd = 0.21 +/-
0.11 mag. With H_0=72 +/- 4 km/s/Mpc, we estimate a positive peculiar velocity
of 1225 +/- 235 km/s for Hydra and 210 +/- 295 km/s for the Cen30 component of
Centaurus. Allowing for a thermal velocity dispersion of 200 km/s, this rules
out a common peculiar flow velocity for both clusters at 98% confidence. We
find that the 9*10^{15} M_{sun} ``Great Attractor'' from the flow study of
Tonry et al. (2000) at a distance of ~45 Mpc can explain the observed peculiar
velocities if shifted about 15 degrees towards the Hydra cluster position. Our
results are inconsistent at 94% confidence with a scenario where the Centaurus
cluster is identical to the Great Attractor. In order to better restrict
partially degenerate Great Attractor parameters like its mass and distance, a
recalculation of the local flow model with updated distance information over a
larger area than covered by us would be needed.


title: The Tully-Fisher relation of distant cluster galaxies

abstract:
  We have measured maximum rotation velocities (Vrot) for a sample of 111
emission-line galaxies with 0.1 < z < 1, observed in the fields of 6 clusters.
  From these data we construct 'matched' samples of 58 field and 22 cluster
galaxies, covering similar ranges in redshift (0.25 < z < 1.0) and luminosity
(M_B < -19.5 mag), and selected in a homogeneous manner. We find the
distributions of M_B, Vrot, and scalelength, to be very similar for the two
samples. However, using the Tully-Fisher relation (TFR) we find that cluster
galaxies are systematically offset with respect to the field sample by
-0.7+-0.2 mag. This offset is significant at 3 sigma and persists when we
account for an evolution of the field TFR with redshift. Extensive tests are
performed to investigate potential differences between the measured emission
lines and derived rotation curves of the cluster and field samples. However, no
such differences which could affect the derived Vrot values and account for the
offset are found. The most likely explanation for the TFR offset is that giant
spiral galaxies in distant clusters are on average brighter, for a given
rotation velocity, than those in the field. We discuss the potential mechanisms
responsible for this, and consider alternative explanations.


title:
On the relation between circular velocity and central velocity
  dispersion in high and low surface brightness galaxies

abstract:
  In order to investigate the correlation between the circular velocity Vc and
the central velocity dispersion of the spheroidal component sigma_c, we
analyzed these quantities for a sample of 40 high surface brightness disc
galaxies (hereafter HSB), 8 giant low surface brightness spiral galaxies
(hereafter LSB), and 24 elliptical galaxies characterized by flat rotation
curves. We find that the Vc-sigma_c relation is descri ed by a linear law out
to velocity dispersions as low as sigma_c~50km/s, while in previous works a
power law was adopted for galaxies with sigma_c>80k/ms.
  Elliptical galaxies with Vc based on dynamical models or directly derived
from the HI rotation curves follow the same relation as the HSB galaxies in the
Vc-sigma_c plane. On the contrary, the LSB galaxies follow a different
relation, since most of them show either higher Vc (or lower sigma_c) with
respect to the HSB galaxies. This argues against the relevance of baryon
collapse in the radial density profile of the dark matter haloes of LSB
galaxies. (abridged)


title: Star-Cluster Astrometry with Ground-Based Wide Field Imagers

abstract:
  We show the astrometric potential of the Wide Field Imager at the focus of
the MPI-ESO 2.2m Telescope. Currently, we are able to measure the position of a
well-exposed star with a precision of $\sim$4 mas/frame in each coordinate
(under 0.8 arcsec seeing conditions). We present some preliminary results here.


title:
The Radial Distribution of Magnetic Helicity in the Solar Convective
  Zone: Observations and Dynamo Theory

abstract:
  We continue our attempt to connect observational data on current helicity in
solar active regions with solar dynamo models. In addition to our previous
results about temporal and latitudinal distributions of current helicity
(Kleeorin et al. 2003), we argue that some information concerning the radial
profile of the current helicity averaged over time and latitude can be
extracted from the available observations. The main feature of this
distribution can be presented as follows. Both shallow and deep active regions
demonstrate a clear dominance of one sign of current helicity in a given
hemisphere during the whole cycle. Broadly speaking, current helicity has
opposite polarities in the Northern and Southern hemispheres, although there
are some active regions that violate this polarity rule. The relative number of
active regions violating the polarity rule is significantly higher for deeper
active regions. A separation of active regions into `shallow', `middle' and
`deep' is made by comparing their rotation rate and the helioseismic rotation
law. We use a version of Parker's dynamo model in two spatial dimensions, that
employs a nonlinearity based on magnetic helicity conservation arguments. The
predictions of this model about the radial distribution of solar current
helicity appear to be in remarkable agreement with the available observational
data; in particular the relative volume occupied by the current helicity of
"wrong" sign grows significantly with the depth.


title:
Atmospheric dynamics in carbon-rich Miras. I. Model atmospheres and
  synthetic line profiles

abstract:
  Atmospheres of evolved AGB stars are heavily affected by pulsation, dust
formation and mass loss, and they can become very extended. Time series of
observed high-resolution spectra proved to be a useful tool to study
atmospheric dynamics throughout the outer layers of these pulsating red giants.
Originating at various depths, different molecular spectral lines observed in
the near-infrared can be used to probe gas velocities there for different
phases during the lightcycle. Dynamic model atmospheres are needed to represent
the complicated structures of Mira variables properly. An important aspect
which should be reproduced by the models is the variation of line profiles due
to the influence of gas velocities. Based on a dynamic model, synthetic spectra
(containing CO and CN lines) were calculated, using an LTE radiative transfer
code that includes velocity effects. It is shown that profiles of lines that
sample different depths qualitatively reproduce the behaviour expected from
observations.


title: Atmospheric dynamics in carbon-rich Miras. II. Models meet observations

abstract:
  Originating in different depths of the very extended atmospheres of AGB
stars, various molecular spectral lines observable in the near-infrared show
diverse behaviours and can be used to probe atmospheric dynamics throughout the
outer layers of these pulsating red giants. In Nowotny et al. (2005, Paper I)
time series of synthetic high-resolution spectra were presented, computed from
a dynamic model atmosphere for a typical carbon-rich Mira. In this work, line
profile shapes, their variations during the lightcycle and radial velocities
derived from wavelength shifts are analyzed and compared with results from
observed FTS spectra of the C-rich Mira S Cep and other Miras. It is found that
the global velocity structure of the model is in qualitative agreement with
observations. Radial velocities of molecular lines sampling different layers
behave comparably, although some differences are apparant concerning absolute
values. A correction factor of p=1.36 between measured RVs and actual gas
velocities is derived for CO dv=3 lines. It is shown that dynamic model
atmospheres are capable of reproducing Mira spectra without introducing an
additional ''static layer'' proposed by several authors.


title: Synthetic Line Profiles for Pulsating Red Giants

abstract:
  Pulsation influences atmospheric structures of variable AGB stars (Miras)
considerably. Spectral lines of the CO dv=3 vibration-rotation bands (at
1.6mue) therefore have a very characteristic appearance in time series of
high-resolution spectra. Coupled to the light cycle they can be observed blue-
or red-shifted, for some phases even line doubling is found. This is being
explained by radial pulsations and shock fronts emerging in the atmospheres.
Based on dynamic model atmospheres synthetic CO line profiles were calculated
consistently, reproducing this scenario qualitatively.


title:
The VLT-FLAMES Survey of Massive Stars: Observations in the Galactic
  Clusters NGC 3293, NGC 4755 and NGC 6611

abstract:
  We introduce a new survey of massive stars in the Galaxy and the Magellanic
Clouds using the Fibre Large Array Multi-Element Spectrograph (FLAMES)
instrument at the Very Large Telescope (VLT). Here we present observations of
269 Galactic stars with the FLAMES-Giraffe Spectrograph (R ~ 25,000), in fields
centered on the open clusters NGC 3293, NGC 4755 and NGC 6611. These data are
supplemented by a further 50 targets observed with the Fibre-Fed Extended Range
Optical Spectrograph (FEROS, R = 48,000). Following a description of our
scientific motivations and target selection criteria, the data reduction
methods are described; of critical importance the FLAMES reduction pipeline is
found to yield spectra that are in excellent agreement with less automated
methods. Spectral classifications and radial velocity measurements are
presented for each star, with particular attention paid to morphological
peculiarities and evidence of binarity. These observations represent a
significant increase in the known spectral content of NGC 3293 and NGC 4755,
and will serve as standards against which our subsequent FLAMES observations in
the Magellanic Clouds will be compared.


title: X-ray line tomography of AGN-induced motion in clusters of galaxies

abstract:
  The thermal broadening of emission lines of heavy ions is small enough such
that Doppler shifts due to bulk motions may be detected with the next
generation of X-ray observatories. This opens up the possibility to study gas
velocities in the intra-cluster medium. Here we study the effect of bulk
motions induced by a central active galactic nucleus (AGN) on the emission
lines around the FeXXV complex. We have modelled the evolution of AGN-induced
bubbles in a realistic cosmological framework and studied the resulting FeXXV
line profiles. We found that in clusters with AGN feedback, motions induced by
the inflation of bubbles and their buoyant rise lead to distinct features in
the iron emission lines that are detectable with a spectral resolution of about
10 eV. These observations will help to determine the mechanical energy that
resides in the bubbles and thereby the kinetic luminosity of the AGN.


title:
Are rotation curves in NGC 6946 and the Milky Way magnetically
  supported?

abstract:
  Following the model of magnetically supported rotation of spiral galaxies,
the inner disk rotation is dominated by gravity but magnetism is not negligible
at radii where the rotation curve becomes flat, and indeed becomes dominant at
very large radii. Values of the order of 1 $\mu$G, or even less, produce a
centripetal force when the absolute value of the slope of the curve [$B_\phi$,
R] (azimuthal field strength versus radius) is less than $R^{-1}$. The
$R^{-1}$-profile is called the critical profile. From this hypothesis, the
following is to be expected: at large radii, a ``subcritical'' profile (slope
flatter than $R^{-1}$); at still larger radii a $B_\phi$-profile becoming
asymptotically critical as the density becomes asymptotically vanishing. Recent
observations of magnetic fields in NGC 6946 and the Milky Way are in very good
agreement with these predictions. This magnetic alternative requires neither
galactic dark matter (DM) nor modification of fundamental laws of physics, but
it is not in conflict with these hypotheses, especially with the existence of
cosmological cold dark matter (CDM).


title: X-ray Orbital Modulations in Intermediate Polars

abstract:
  We present an analysis of 30 archival ASCA and RXTE X-ray observations of 16
intermediate polars to investigate the nature of their orbital modulation. We
show that X-ray orbital modulation is widespread amongst these systems, but not
ubiquitous as indicated by previous studies that included fewer objects. Only
seven of the sixteen systems show a clearly statistically significant
modulation depth whose amplitude decreases with increasing X-ray energy.
Interpreting this as due to photoelectric absorption in material at the edge of
an accretion disc would imply that such modulations are visible for all system
inclination angles in excess of 60 degrees. However, it is also apparent that
the presence of an X-ray orbital modulation can appear and disappear on a
timescale of ~years or months in an individual system. This may be evidence for
the presence of a precessing, tilted accretion disc, as inferred in some low
mass X-ray binaries.


title: Neutrino emissivity under neutral kaon condensation

abstract:
  Neutrino emissivity from neutron star matter with neutral kaon condensate is
considered. It is shown that a new cooling channel is opened, and what is more,
all previously known channels acquire the greater emissivity reaching the level
of the direct URCA cycle in normal matter.


title:
The HARPS search for southern extra-solar planets. III. Three
  Saturn-mass planets around HD 93083, HD 101930 and HD 102117

abstract:
  We report on the detection of three Saturn-mass planets discovered with the
HARPS instrument. HD 93083 shows radial-velocity (RV) variations best explained
by the presence of a companion of 0.37 M_Jup orbiting in 143.6 days. HD 101930
b has an orbital period of 70.5 days and a minimum mass of 0.30 M_Jup. For HD
102117, we present the independent detection of a companion with m2sini = 0.14
M_Jup and orbital period P = 20.7 days. This planet was recently detected by
Tinney et al. (2004). Activity and bisector indicators exclude any significant
RV perturbations of stellar origin, reinforcing the planetary interpretation of
the RV variations. The radial-velocity residuals around the Keplerian fits are
2.0, 1.8 and 0.9 m/s respectively, showing the unprecedented RV accuracy
achieved with HARPS. A sample of stable stars observed with HARPS is also
presented to illustrate the long-term precision of the instrument. All three
stars are metal-rich, confirming the now well-established relation between
planet occurrence and metallicity. The new planets are all in the Saturn-mass
range, orbiting at moderate distance from their parent star, thereby occupying
an area of the parameter space which seems difficult to populate according to
planet formation theories. A systematic exploration of these regions will
provide new constraints on formation scenarios in the near future.


title: Tip-tilt Error in Lyot Coronagraphs

abstract:
  The direct detection of extrasolar planets by imaging means is limited by the
large flux of light from the host star being scattered into the region of
interest by a variety of processes, including diffraction. Coronagraphs are
devices that suppress the undesirable scattering of light caused by
diffraction. In a coronagraph the sensitivity limit for high dynamic range is
limited by the propagation of errors introduced by the imperfect optical system
to the final image. In this paper we develop theory and simulations to
understand how such errors propagate in a coronagraph. We describe the response
of classical and band-limited Lyot coronagraphs to small and large errors in
the placement of the central star, and identify ways of making such
coronagraphs more robust to small guiding errors. We also uncover features of
the decentered PSF that can lead to spurious detection of companions,
especially with aggressive, high dynamic range coronagraphs dedicated to
companion searches aimed at finding extrasolar terrestrial or Jovian planets.


title:
A non-LTE analysis of the spectra of two narrow lined main sequence
  stars in the SMC

abstract:
  An analysis of high-resolution VLT/UVES spectra of two B-type main sequence
stars, NGC 346-11 and AV 304, in the Small Magellanic Cloud (SMC), has been
undertaken, using the non-LTE TLUSTY model atmospheres to derive the stellar
parameters and chemical compositions of each star. The chemical compositions of
the two stars are in reasonable agreement. Moreover, our stellar analysis
agrees well with earlier analyses of H II regions. The results derived here
should be representative of the current base-line chemical composition of the
SMC interstellar medium as derived from B-type stars.


title:
The precision of large radio continuum source catalogues- An application
  of the SPECFIND tool

abstract:
  The accuracy in position and flux density of 19 large radio continuum source
catalogues has been determined using SPECFIND, a new tool recently made
available through the CDS. The ~67000 radio continuum spectra with three or
more frequencies produced by SPECFIND were used to cross-correlate sources from
different catalogues and to calculate offsets in right ascension and
declination in the various catalogues with respect to the positions given in
the NRAO VLA Sky Survey (NVSS) catalogue, which was adopted as a reference. The
flux densities reported in the catalogues were compared to those predicted by
the composite spectra, enabling us to assess the quality of the flux density
calibration of the different catalogues.


title: Gravitational Lensing of stars in the central arcsecond of our Galaxy

abstract:
  In the neighborhood of Sgr A*, several stars (S2, S12, S14, S1, S8, S13)
enjoy an accurate determination of their orbital parameters. General Relativity
predicts that the central black hole acts as a gravitational lens on these
stars, generating a secondary image and two infinite series of relativistic
images. For each of these six stars, we calculate the light curves for the
secondary and the first two relativistic images, in the Schwarzschild black
hole hypothesis, throughout their orbital periods. The curves are peaked around
the periapse epoch, but two subpeaks may arise in nearly edge-on orbits, when
the source is behind or in front of Sgr A*. We show that for most of these
stars the secondary image should be observable during its brightness peak. In
particular, S14 is the best candidate, since its secondary image reaches K=23.3
with an angular separation of 0.125 mas from the apparent horizon of the
central black hole. The detection of such images by future instruments could
represent the first observation of gravitational lensing beyond the weak field
approximation.


title:
The XMM-Newton view of the relativistic spectral features in
  AXJ0447-0627

abstract:
  The XMM-Newton observation of the optically Type 1 AGN AXJ0447-0627 (z=0.214)
unambiguously reveals a complex, bright and prominent set of lines in the 4-8
keV rest frame energy range. Although, from a phenomenological point of view,
the observed properties can be described by a simple power law model plus 5
narrow Gaussian lines (at rest frame energies of nearly 4.49, 5.55, 6.39, 7.02
and 7.85 keV), we find that a model comprising a power law (Gamma of the order
of 2.2), a reflected relativistic continuum, a narrow Fe I Kalpha line from
neutral material as well as a broad Fe Kalpha relativistic line from a ionized
accretion disk represents a good physical description of the data. The ''double
horned'' profile of the relativistic line implies an inclination of the
accretion disk of the order of 45 degree, and an origin in a narrow region of
the disk, from R_in of the order of 19 GM/c^2 to R_out of the order of 30
GM/c^2. The narrow Fe I Kalpha line from neutral material is probably produced
far from the central black hole, most likely in the putative molecular torus.
Although some of these properties have been already found in other Type 1 AGN
and discussed in the literature, at odd with the objects reported so far we
measure high equivalent widths (EWs) of the observed lines: nearly 1.4 keV for
the ``double horned'' relativistic line and nearly 0.4 keV for the narrow line.


title: Finding SZ clusters in the ACBAR maps

abstract:
  We present a new method for component separation from multifrequency maps
aimed to extract Sunyaev-Zeldovich (SZ) galaxy clusters from Cosmic Microwave
Background (CMB) experiments. This method is best suited to recover
non--Gaussian, spatially localized and sparse signals. We apply our method on
simulated maps of the ACBAR experiment. We find that this method improves the
reconstruction of the integrated $y$ parameter by a factor three with respect
to the Wiener filter case. Moreover, the scatter associated with the
reconstruction is reduced by 30 per cent.


title:
Laboratory Measurement and Theoretical Modeling of K-shell X-ray Lines
  from Inner-shell Excited and Ionized Ions of Oxygen

abstract:
  We present high resolution laboratory spectra of K-shell X-ray lines from
inner-shell excited and ionized ions of oxygen, obtained with a reflection
grating spectrometer on the electron beam ion trap (EBIT-I) at the Lawrence
Livermore National Laboratory. Only with a multi-ion model including all major
atomic collisional and radiative processes, are we able to identify the
observed K-shell transitions of oxygen ions from \ion{O}{3} to \ion{O}{6}. The
wavelengths and associated errors for some of the strongest transitions are
given, taking into account both the experimental and modeling uncertainties.
The present data should be useful in identifying the absorption features
present in astrophysical sources, such as active galactic nuclei and X-ray
binaries. They are also useful in providing benchmarks for the testing of
theoretical atomic structure calculations.


title: The Rigidly Rotating Magnetosphere of Sigma Ori E

abstract:
  We attempt to characterize the observed variability of the magnetic
helium-strong star sigma Ori E in terms of a recently developed rigidly
rotating magnetosphere model. This model predicts the accumulation of
circumstellar plasma in two co-rotating clouds, situated in magnetohydrostatic
equilibrium at the intersection between magnetic and rotational equators. We
find that the model can reproduce well the periodic modulations observed in the
star's light curve, H alpha emission-line profile, and longitudinal field
strength, confirming that it furnishes an essentially correct, quantitative
description of the star's magnetically controlled circumstellar environment.


title:
Quantum corrections to slow roll inflation and new scaling of
  superhorizon fluctuations

abstract:
  Precise cosmological data from WMAP and forthcoming CMB experiments motivate
the study of the quantum corrections to the slowroll inflationary parameters.We
find the quantum (loop) corrections to the equations of motion of the classical
inflaton, its quantum fluctuations and the Friedmann equation in general single
field slow roll inflation.We implement a renormalized effective field theory
EFT approach based on an expansion in (H/M_{Pl})^2 and slow roll parameters
epsilon_V,eta_V,sigma_V, xi_V.We find that the leading order quantum
corrections to the inflaton effective potential and its equation of motion are
determined by the power spectrum of scalar fluctuations. Its near scale
invariance introduces a strong infrared behavior naturally regularized by the
slow roll parameter Delta = eta_V-epsilon_V=(n_s-1)/2+r/8.To leading order in
the EFT and slow roll expansions we find
V_{eff}(Phi_0)=V_R(Phi_0)[1+(Delta^2_T/32)(n_s-1+3r/8) /(n_s-1+r/4)+higher
orders]where n_s and r=Delta^2_T/Delta^2_R are the CMB observables that depend
implicitly on Phi_0, and V_R(Phi_0) is the renormalized classical inflaton
potential.This effective potential during slow roll inflation is strikingly
different from the Minkowski space-time result.Superhorizon scalar field
fluctuations grow for late times eta -> 0^- as |\eta|^{-1+Delta-d_} where d_ is
a novel quantum correction to the scaling exponent related to the self decay of
superhorizon inflaton fluctuations eta is the conformal time. We generalize
this to the case of the inflaton interacting with a light scalar field. These
quantum corrections arising from interactions will compete with higher order
slow-roll corrections and must be taken into account for the precision
determination of inflationary parameters.


title:
The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. I.
  Chamaeleon II Observed with MIPS

abstract:
  We present maps of over 1.5 square degrees in Chamaeleon (Cha) II at 24, 70,
and 160 micron observed with the Spitzer Space Telescope Multiband Imaging
Photometer for Spitzer (MIPS) and a 1.2 square degree millimeter map from SIMBA
on the Swedish-ESO Submillimetre Telescope (SEST). The c2d Spitzer Legacy
Team's data reduction pipeline is described in detail. Over 1500 24 micron
sources and 41 70 micron sources were detected by MIPS with fluxes greater than
10-sigma. More than 40 potential YSOs are identified with a MIPS and 2MASS
color-color diagram and by their spectral indices, including two previously
unknown sources with 24 micron excesses. Our new SIMBA millimeter map of Cha II
shows that only a small fraction of the gas is in compact structures with high
column densities. The extended emission seen by MIPS is compared with previous
CO observations. Some selected interesting sources, including two detected at 1
mm, associated with Cha II are discussed in detail and their SEDs presented.
The classification of these sources using MIPS data is found to be consistent
with previous studies.


title:
The X-ray Position and Optical Counterpart of the Accretion-Powered
  Millisecond Pulsar XTE J1814-338

abstract:
  We report the precise optical and X-ray localization of the 3.2 ms
accretion-powered X-ray pulsar XTE J1814-338 with data from the Chandra X-Ray
Observatory as well as optical observations conducted during the 2003 June
discovery outburst. Optical imaging of the field during the outburst of this
soft X-ray transient reveals an R = 18 star at the X-ray position. This star is
absent (R > 20) from an archival 1989 image of the field and brightened during
the 2003 outburst, and we therefore identify it as the optical counterpart of
XTE J1814-338. The best source position derived from optical astrometry is R.A.
= 18h13m39.s04, Dec.= -33d46m22.3s (J2000). The featureless X-ray spectrum of
the pulsar in outburst is best fit by an absorbed power-law (with photon index
= 1.41 +- 0.06) plus blackbody (with kT = 0.95 +- 0.13 keV) model, where the
blackbody component contributes approximately 10% of the source flux. The
optical broad-band spectrum shows evidence for an excess of infrared emission
with respect to an X-ray heated accretion disk model, suggesting a significant
contribution from the secondary or from a synchrotron-emitting region. A
follow-up observation performed when XTE J1814-338 was in quiescence reveals no
counterpart to a limiting magnitude of R = 23.3. This suggests that the
secondary is an M3 V or later-type star, and therefore very unlikely to be
responsible for the soft excess, making synchroton emission a more reasonable
candidate.


title:
The orbital statistics of stellar inspiral and relaxation near a massive
  black hole: characterizing gravitational wave sources

abstract:
  We study the orbital parameters distribution of stars that are scattered into
nearly radial orbits and then spiral into a massive black hole (MBH) due to
dissipation, in particular by emission of gravitational waves (GW). This is
important for GW detection, e.g. by the Laser Interferometer Space Antenna
(LISA). Signal identification requires knowledge of the waveforms, which depend
on the orbital parameters. We use analytical and Monte Carlo methods to analyze
the interplay between GW dissipation and scattering in the presence of a mass
sink during the transition from the initial scattering-dominated phase to the
final dissipation-dominated phase of the inspiral. Our main results are (1)
Stars typically enter the GW-emitting phase with high eccentricities. (2) The
GW event rate per galaxy is a few per Gyr for typical central stellar cusps,
almost independently of the relaxation time or the MBH mass. (3) For
intermediate mass black holes (IBHs) of ~a thousand solar masses such as may
exist in dense stellar clusters, the orbits are very eccentric and the inspiral
is rapid, so the sources are very short-lived.


title: On the Rotation Period of (90377) Sedna

abstract:
  We present precise, ~1%, r-band relative photometry of the unusual solar
system object (90377) Sedna. Our data consist of 143 data points taken over
eight nights in October 2004 and January 2005. The RMS variability over the
longest contiguous stretch of five nights of data spanning nine days is only
1.3%. This subset of data alone constrain the amplitude of any long-period
variations with period P to be A<1% (P/20 days)^2. Over the course of any given
5-hour segment, the data exhibits significant linear trends not seen in a
comparison star of similar magnitude, and in a few cases these segments show
clear evidence for curvature at the level of a few millimagnitudes per hour^2.
These properties imply that the rotation period of Sedna is O(10 hours), cannot
be < 5 hours, and cannot be >10 days, unless the intrinsic light curve has
significant and comparable power on multiple timescales, which is unlikely. A
sinusoidal fit yields a period of P=(10.273 +/- 0.002) hours and semi-amplitude
of A=(1.1 +/- 0.1)%. There are additional acceptable fits with flanking periods
separated by ~3 minutes, as well as another class of fits with P ~ 18 hours,
although these later fits appear less viable based on visual inspection. Our
results indicate that the period of Sedna is likely consistent with typical
rotation periods of solar system objects, thus obviating the need for a massive
companion to slow its rotation.


title:
Galactic Wind Effects on the Lyman-alpha Absorption in the Vicinity of
  Galaxies

abstract:
  We present predictions of Ly-alpha forest-galaxy correlations at z=3 from
Eulerian simulations that include the effects of galactic winds, driven
primarily by supernova explosions. Galactic winds produce expanding bubbles of
shock-heated gas within ~0.5 comoving Mpc/h of luminous galaxies in the
simulation, which have space density similar to that of observed Lyman break
galaxies (LBGs). However, most of the low-density intergalactic gas that
determines the observed properties of the Ly-alpha forest is unaffected by
winds. The impact of winds on the Ly-alpha optical depth near galaxies is less
dramatic than their impact on gas temperature because winds heat only a small
fraction of the gas present in the turnaround regions surrounding galaxies.
Hence, Ly-alpha absorption from gas outside the wind bubbles is spread out over
the same velocity range occupied by the wind-heated gas. In general, Ly-alpha
absorption is expected to be stronger than average near galaxies because of the
high gas density. Winds result in a modest reduction of this expected increase
of Ly-alpha absorption. Our predictions can be compared to future observations
to detect the wind effects and infer their strength, although with the caveat
that the results are still dependent on the correspondence of simulated
galaxies and observed LBGs. We find that wind effects in our simulations are
not strong enough to reproduce the high Ly-alpha transmission within 0.5 Mpc/h
comoving of galaxies that has been suggested by recent observations; powerful
galactic explosions or ejecta with hyper-escape velocities would be required,
but these are unlikely to be produced by ordinary star formation and supernovae
alone


title:
A Comparison of Stellar and Gaseous Kinematics in the Nuclei of Active
  Galaxies

abstract:
  To investigate the relationship between black holes and their host galaxies,
many groups have used the width of the [O III] 5007 line as a substitute for
the stellar velocity dispersion (sigma*) of galaxy bulges. We directly test
this assumption with a large and homogeneous sample of narrow-line active
galactic nuclei from the Sloan Digital Sky Survey. We consider multiple
transitions ([O II] 3727, [O III] 5007, and [S II] 6716, 6731) and various
techniques for quantifying the line width in order to obtain a calibration
between the gas velocity dispersion, sigma_g, and sigma*. We find that sigma_g
of the low-ionization lines traces sigma*, as does sigma_g for the core of [O
III] after its asymmetric blue wing is properly removed, although in all cases
the correlation between sigma_g and sigma* has considerable scatter. While the
gas kinematics of the narrow-line region of active galaxies are primarily
governed by the gravitational potential of the stars, the accretion rate, as
traced by the Eddington luminosity ratio, seems to play an important secondary
role. Departures from virial motions correlate systematically with accretion
rate. We discuss the implications of these results for previous studies that
use [O III] line widths to infer stellar velocity dispersions in quasars and
narrow-line Seyfert 1 galaxies.


title: The effects of feedback on the morphology of galaxy discs

abstract:
  We have performed hydrodynamic simulations of galaxy formation in a LCDM
universe. We have followed galaxy formation in a dark matter halo, chosen to
have a relatively quiet recent merger history, using different models for star
formation and feedback. In all cases, we have adopted a multi-phase description
of the interstellar medium and modelled star formation in quiescent and burst
modes. We have explored two triggers for starbursts: strong shocks and high gas
density, allowing for the possibility that stars in the burst may form with a
top-heavy initial mass function. We find that the final morphology of the
galaxy is extremely sensitive to the modelling of star formation and feedback.
Starting from identical initial conditions, galaxies spanning the wide range of
Hubble types, with B-band disc-to-total luminosity ratios ranging from 0.25 to
0.9, can form in the same dark matter halo. Models in which starbursts are
induced by high gas density (qualitatively similar to models in which feedback
is produced by AGN) generate energetic winds and result in galaxies with an
early-type morphology. Models in which the starbursts are induced by strong
shocks lead to extended discs. In this case, the feedback associated with the
bursts suppresses the collapse of baryons in small halos, helping to create a
reservoir of hot gas that is available for cooling after $z = 1$, following the
bulk of the dynamical activity that builds up the halo. This gas then cools to
form a large, young stellar disc.


title:
On the fine structure of the sunspot penumbrae. II. The nature of the
  Evershed flow

abstract:
  We investigate the fine structure of the sunspot penumbra by means of a model
that allows for a flux tube in horizontal pressure balance with the magnetic
background atmosphere in which it is embedded. We apply this model to
spectropolarimetric observations of two neutral iron lines at 1.56 $\mu$m and
invert several radial cuts in the penumbra of the same sunspot at two different
heliocentric angles. In the inner part of the penumbra we find hot flux tubes
that are somewhat inclined to the horizontal. They become gradually more
horizontal and cooler with increasing radial distance. This is accompanied by
an increase in the velocity of the plasma and a decrease of the gas pressure
difference between flux tube and the background component. At large radial
distances the flow speed exceeds the critical speed and evidence is found for
the formation of a shock front. These results are in good agreement with
simulations of the penumbral fine structure and provide strong support for the
siphon flow as the physical mechanism driving the Evershed flow.


title: Late-time X-Ray, UV and Optical Monitoring of Supernova 1979C

abstract:
  We present results from observations of SN 1979C with XMM-Newton in X-rays
and in the UV, archival X-ray and HST data, and follow-up ground-based optical
imaging. The XMM-Newton MOS spectrum shows two-temperature thermal plasma
emission characteristics of both the forward (4.1 keV) and reverse shock (0.78
keV) with no intrinsic absorption. The long-term X-ray lightcurve of SN 1979C
shows no sign of a decline over 16-23 yrs after its outburst. The high X-ray
luminosity (8 x 10^38 ergs/s) is caused by the interaction of the shock with
dense circumstellar matter, likely deposited by a strong stellar wind from the
progenitor with a high mass-loss rate of 1.5 x 10^-4 M_sun/yr. The X-ray data
support a strongly decelerated shock and show a mass-loss rate history which is
consistent with a constant progenitor mass-loss rate and wind velocity over the
past >16,000 yrs in the evolution of the progenitor. We find a CSM density
profile of rho_CSM \propto r^-s with index s<1.7 and high CSM densities (>10^4
cm^-3) out to large radii from the site of the explosion (> 4 x 10^17 cm).
Using XMM-Newton Optical Monitor data we further detect optical/UV emission
from SN 1979C, with B, U, and UVW1-band lum. of 5,7, and 9 x 10^36 ergs/s. The
young stellar cluster in the vicinity of the SN, as imaged by the HST and
follow-up ground-based optical imaging, can only provide a fraction of the
total observed flux, so that a significant contribution to the output likely
arises from the strong interaction of SN 1979C with dense CSM.


title: The Sloan Digital Sky Survey Quasar Catalog III. Third Data Release

abstract:
  We present the third edition of the Sloan Digital Sky Survey (SDSS) Quasar
Catalog. The catalog consists of the 46,420 objects in the SDSS Third Data
Release that have luminosities larger than M_i = -22 (in a cosmology with H_0 =
70 km/s/Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7), have at least one emission
line with FWHM larger than 1000 km/s or are unambiguously broad absorption line
quasars, are fainter than i = 15.0, and have highly reliable redshifts. The
area covered by the catalog is 4188 sq. deg. The quasar redshifts range from
0.08 to 5.41, with a median value of 1.47; the high-redshift sample includes
520 quasars at redshifts greater than four, of which 17 are at redshifts
greater than five. For each object the catalog presents positions accurate to
better than 0.2 arcsec. rms per coordinate, five-band (ugriz) CCD-based
photometry with typical accuracy of 0.03 mag, and information on the morphology
and selection method. The catalog also contains radio, near-infrared, and X-ray
emission properties of the quasars, when available, from other large-area
surveys. The calibrated digital spectra cover the wavelength region 3800--9200A
at a spectral resolution about 2000; the spectra can be retrieved from the
public database using the information provided in the catalog. A total of
44,221 objects in the catalog were discovered by the SDSS; 28,400 of the SDSS
discoveries are reported here for the first time.


title: A Separate Universe Approach to Quintessence Perturbations

abstract:
  There is some observational evidence that the dark energy may not be smooth
on large scales. This makes it worth while to try and get as simple and as
intuitive a picture of how dark energy perturbations behave so as to be able to
better constrain possible models of dark energy and the generation of large
scale perturbations. The separate Universe method provides an easy way to
evaluate cosmological perturbations, as all that is required is an
understanding of the background behavior. Here, this method is used to show how
the size of the dark energy perturbations, preferred by observations, is larger
than would be expected, and so some mechanism may be required to amplify them.


title:
Filaments as Possible Signatures of Magnetic Field Structure in
  Planetary Nebulae

abstract:
  We draw attention to the extreme filamentary structures seen in
high-resolution optical images of certain planetary nebulae. We determine the
physical properties of the filaments in the nebulae IC 418, NGC 3132, and NGC
6537, and based on their large length-to-width ratios, longitudinal coherence,
and morphology, we suggest that they may be signatures of the underlying
magnetic field. The fields needed for the coherence of the filaments are
probably consistent with those measured in the precursor circumstellar
envelopes. The filaments suggest that magnetic fields in planetary nebulae may
have a localized and thread-like geometry.


title: The cooling function of HD molecule revisited

abstract:
  We report new calculations of the cooling rate of primordial gas by the HD
molecule, taking into account its ro-vibrational structure. The HD cooling
function is calculated including radiative and collisional transitions for
J\le8 rotational levels, and for the vibrational levels v=0,1,2 and 3. The
ro-vibrational level population is calculated from the balance equation
assuming steady state. The cooling function is evaluated in the ranges of the
kinetic temperatures, T_k, from 1e2 to 2e4 K and the number densities, n_H,
from 1 to 1e8 cm**-3. We find that the inclusion of collisional ro-vibrational
transitions increases significantly the HD cooling efficiency, in particular
for high densities and temperatures. For n_H>~1e5 and T_k~1e4 K the cooling
function becomes more than an order of magnitude higher than previously
reported. We give also the HD cooling rate in the presence of the cosmic
microwave radiation field for radiation temperatures of 30, 85 and 275 K
(redshifts of 9, 29 and 99). The tabulated cooling functions are available at
http://www.cifus.uson.mx/Personal\_Pages/anton/DATA/HD\_cooling/HD\_cool.html.
We discuss the relevance to explore the effects of including our results into
models and simulations of galaxy formation, especially in the regime when gas
cools down from temperatures above ~3000 K.


title: The Local Shape of the Universe in the Inflationary Limit

abstract:
  Recent high precision data by WMAP and SDSS have provided strong evidence to
suggest that the universe is nearly flat. They are also making it possible to
probe the topology of the universe. Motivated by these results, we have
recently studied the consequences of taking the inflationary limit, i.e.
$|\Omega_0 - 1| << 1$. We have shown that in this limit a generic detectable
spherical or hyperbolic topology is locally indistinguishable from either $R^2
x S^1$ or $R x T^2$, irrespective of its global shape. Here we briefly present
these results and further discuss their observational implications.


title: Two Pulsar Wind Nebulae: Chandra/XMM-Newton Imaging of GeV J1417-6100

abstract:
  We report on Chandra ACIS and XMM-Newton MOS/PN imaging observations of two
pulsar wind nebulae (K3/PSR J1420-6048 and G313.3+0.1=`the rabbit') associated
with the Galactic unidentified gamma-ray source GeV J1417-6100. With the
excellent ACIS imaging, the very energetic pulsar PSR J1420-6048 is separated
from its surrounding nebula. This nebula has surprisingly little compact
structure, although a faint arc is seen near the pulsar. Similarly, two point
sources are resolved in the rabbit nebula. The large XMM-Newton collecting area
provides useful spectral constraints on the rabbit and the associated point
sources. Based on spectra and X-ray morphology, we identify one point source as
a plausible pulsar counterpart. Large backgrounds and low source counts limited
pulse search sensitivities, but we report pulse upper limits and a candidate
108ms period for the rabbit pulsar based on the XMM-Newton data and an ACIS CC
observation. Comparison of the X-ray images with high resolution ATCA radio
maps shows that the non-thermal X-ray emission corresponds well with the radio
structure.


title:
A Chandra X-ray Investigation of the Violent Interstellar Medium: From
  Dwarf Starbursts to Ultraluminous Infrared Galaxies

abstract:
  We have analyzed observations with the Chandra X-ray Observatory of the
diffuse emission by hot gas in 7 dwarf starburst galaxies, 6 edge-on starburst
galaxies, and 9 Ultra Luminous Infrared Galaxies. These systems cover ranges of
\~ 10^4 in X-ray luminosity and several thousand in star formation rate and
K-band luminosity (a proxy for stellar mass). Despite this range in fundamental
parameters, we find that the properties of the diffuse X-ray emission are very
similar in all three classes of starburst galaxies. The spectrum of the diffuse
emission is well fit by thermal emission from gas with kT ~ 0.25 to 0.8 keV and
with several-times-solar abundance ratios of alpha elements to Fe. The ratio of
the thermal X-ray to far-infrared luminosity is roughly constant, as is the
characteristic surface brightness of the diffuse X-ray emission. The size of
the diffuse X-ray source increases systematically with both far-infrared and
K-Band luminosity. All three classes show strong morphological relationships
between the regions of hot gas probed by the diffuse X-ray emission and the
warm gas probed by optical line emission. These findings suggest that the same
physical mechanism is producing the diffuse X-ray emission in the three types
of starbursts, and are consistent with that mechanism being shocks driven by a
galactic "superwind'' powered by the kinetic energy collectively supplied by
stellar winds and supernovae in the starburst.


title:
Spectral properties of Three-dimensional Magneto-hydrodynamical
  Accretion Flows

abstract:
  In spite of a large number of global three-dimensional (3D)
magneto-hydrodynamical (MHD) simulations of accretion flows and jets being made
recently, their astrophysical relevance for realistic situations is not well
known. In order to examine to what extent the simulated MHD flows can account
for the observed spectral energy distribution (SED) of Sagittarius A* (Sgr A*),
for the first time we calculate the emergent spectra from 3D MHD flows in a
wide range of wavelengths (from radio to X-ray) by solving the 3D radiative
transfer equations. We use the simulation data by Kato, Mineshige, and Shibata
(2004) and perform Monte Carlo radiative transfer simulations, in which
synchrotron emission/absorption, free-free emission/absorption, and
Compton/inverse Compton scattering are taken into account. We assume two
temperature plasmas and calculate electron temperatures by solving the electron
energy equation. Only thermal electrons are considered. It is found that the 3D
MHD flow generally over-produces X-rays by means of bremsstrahlung radiation
from the regions at large radii. A flatter density profile, r^{-a} with a<1,
than that of the advection-dominated accretion flow (ADAF), r^{-3/2}, is the
main reason for this. If we restrict the size of the emission region to be as
small as 10r_s, where r_s is the Schwarzschild radius, the MHD model can
reproduce the basic features of the observed SED of Sgr A* during its flaring
state. Yet, the spectrum in the quiescent state remains to be understood. We
also calculate the time-dependent spectral changes, finding that the fluxes
fluctuate in a wide range of the frequency and the flux at each wavelength does
not always vary coherently.


title: Analysis of Microlensing Light Curves Induced by Multiple-Planet Systems

abstract:
  To maximize the number of planet detections by increasing efficiency, current
microlensing follow-up observation experiments are focusing on
high-magnification events to search for planet-induced perturbations near the
peak of lensing light curves. It was known that by monitoring
high-magnification events, it is possible to detect multiplicity signatures of
planetary systems. However, it was believed that the interpretation of the
signals and the characterization of the detected multiple-planet systems would
be difficult due to the complexity of the magnification pattern in the central
region combined with the large number of lensing parameters required to model
multiple-planet systems. In this paper, we demonstrate that in many cases the
central planetary perturbations induced by multiple planets can be well
approximated by the superposition of the single planetary perturbations where
the individual planet-primary pairs act as independent binary lens systems
(binary superposition). The validity of the binary-superposition approximation
implies that the analysis of perturbations induced by multiple planets can be
greatly simplified because the anomalies produced by the individual planet
components can be investigated separately by using relatively much simpler
single-planetary analysis, and thus enables better characterization of these
systems.


title:
Out of the darkness: the infrared afterglow of the INTEGRAL burst GRB
  040422 observed with the VLT

abstract:
  GRB 040422 was detected by the INTEGRAL satellite at an angle of only 3
degrees from the Galactic plane. Analysis of the prompt emission observed with
the SPI and IBIS instruments on INTEGRAL are presented. The IBIS spectrum is
well fit by the Band model with a break energy of Eo=56+/-2 keV and
Epeak=41+/-3 keV. The peak flux is 1.8 10^(-7) erg/cm2/s and fluence 3.4
10^(-7) erg/cm2 in the range 20-200 keV. We then present the observations of
the afterglow of GRB 040422, obtained with the ISAAC and FORS 2 instruments at
the VLT less than 2 hours after the burst. We report the discovery of its
near-infrared afterglow, for which we give here the astrometry and photometry.
No detection could have been obtained in the R and I bands, partly due to the
large extinction in the Milky Way. We re-imaged the position of the afterglow
two months later in the Ks band, and detected a likely bright host galaxy. We
compare the magnitude of the afterglow with a those of a compilation of
promptly observed counterparts of previous GRBs, and show that the afterglow of
GRB 040422 lies at the very faint end of the distribution, brighter only than
that of GRB 021211, singled out later and in the optical bands, and GRB 040924
after accounting for Milky Way extinction. This observation suggests that the
proportion of dark GRBs can be significantly lowered by a more systematic use
of 8-m class telescopes in the infrared in the very early hours after the
burst.


title: Constraints on jet X-ray emission in low/hard state X-ray binaries

abstract:
  We show that the combination of the similarities between the X-ray properties
of low luminosity accreting black holes and accreting neutron stars, combined
with the differences in their radio properties argues that the X-rays from
these systems are unlikely to be formed in the relativistic jets. Specifically,
the spectra of extreme island state neutron stars and low/hard state black
holes are known to be indistinguishable, while the power spectra from these
systems are known to show only minor differences beyond what would be expected
from scaling the characteristic variability frequencies by the mass of the
compact object. The spectral and temporal similarities thus imply a common
emission mechanism that has only minor deviations from having all key
parameters scaling linearly with the mass of the compact object, while we show
that this is inconsistent with the observations that the radio powers of
neutron stars are typically about 30 times lower than those of black holes at
the same X-ray luminosity. We also show that an abrupt luminosity change would
be expected when a system makes a spectral state transition from a radiatively
inefficient jet dominated accretion flow to a thin disk dominated flow, but
that such a change is not seen.


title: Cosmology under Milne's shadow

abstract:
  Based on the magnitude--redshift diagram for the sample of supernovae Ia
analysed by Perlmutter et al. (1999), Davis & Lineweaver rule out the special
relativistic interpretation of cosmological redshifts at a confidence level of
23 sigma. Here, we critically reassess this result. Special relativity is known
to describe the dynamics of an empty universe, by means of the Milne kinematic
model. Applying only special-relativistic concepts, we derive the angular
diameter distance and the luminosity distance in the Milne model. In
particular, in this model we do not use the underlying metric in its
Robertson-Walker form, so our exposition is useful for readers without any
knowledge of general relativity. We do however, explicitly use the
special-relativistic Doppler formula for redshift. We apply the derived
luminosity distance to the magnitude--redshift diagram for supernovae Ia of
Perlmutter et al. (1999) and show that special relativity fits the data much
better than that claimed by Davis & Lineweaver. Specifically, using these data
alone, the Milne model is ruled out only at a 2 sigma level. Although not a
viable cosmological model, in the context of current research on supernovae Ia
it remains a useful reference model when comparing predictions of various
cosmological models.