title: Young Kinematically Decoupled Components in Early-Type Galaxies

abstract:
  We present results from a series of follow-up observations of a sub-sample of
the representative SAURON survey elliptical (E) and lenticular (S0) galaxies
using the OASIS integral-field spectrograph. These observations focus on the
central 10" x 10", with roughly double the spatial resolution of the SAURON
observations. This increased spatial resolution reveals a number of interesting
and previously unresolved features in the measured stellar kinematics and
absorption-line strengths. We find that galaxies exhibiting the youngest global
stellar populations (as measured with SAURON) often contain a distinctly young
central region (on scales of a few hundred parsec or less) compared to the rest
of the galaxy. Moreover, these compact, young components are found to be mostly
counter-rotating with respect to the rest of the galaxy. Given that there is no
well-established reason for such young components to `prefer' counter- over
co-rotation, this finding raises the following questions: How common are these
small KDCs as a function of age? Why are there more young than old compact
KDCs? Where are the equivalent co-rotating components? We explore these
questions using simple simulated velocity fields and stellar population models,
and find that the fading of the young component as it evolves, coupled with the
fact that counter-rotating components are more easily detected in the velocity
field, may help explain the observed trends.


title: Population III Star Formation in a Lambda WDM Universe

abstract:
  In this paper we examine aspects of primordial star formation in a gravitino
warm dark matter universe with a cosmological constant. We compare a set of
simulations using a single cosmological realization but with a wide range of
warm dark matter particle masses which have not yet been conclusively ruled out
by observations. The addition of a warm dark matter component to the initial
power spectrum results in a delay in the collapse of high density gas at the
center of the most massive halo in the simulation and, as a result, an increase
in the virial mass of this halo at the onset of baryon collapse. Both of these
effects become more pronounced as the warm dark matter particle mass becomes
smaller. A cosmology using a gravitino warm dark matter power spectrum assuming
a particle mass of m_{WDM} ~ 40keV is effectively indistinguishable from the
cold dark matter case, whereas the m_{WDM} ~ 15 keV case delays star formation
by approx. 10^8 years. There is remarkably little scatter between simulations
in the final properties of the primordial protostar which forms at the center
of the halo, possibly due to the overall low rate of halo mergers which is a
result of the WDM power spectrum. The detailed evolution of the collapsing halo
core in two representative WDM cosmologies is described. At low densities
(n_{b} <= 10^5 cm^{-3}), the evolution of the two calculations is qualitatively
similar, but occurs on significantly different timescales, with the halo in the
lower particle mass calculation taking much longer to evolve over the same
density range and reach runaway collapse. Once the gas in the center of the
halo reaches relatively high densities (n_{b} >= 10^5 cm^{-3}) the overall
evolution is essentially identical in the two calculations.


title: Local dark matter clumps and the cosmic ray positron excess

abstract:
  It has been proposed that the excess in cosmic ray positrons at approximately
8 GeV, observed on both flights of the HEAT balloon experiment, may be
associated with the annihilation of dark matter within the Milky Way halo. In
this paper we demonstrate how the self-annihilation of neutralino dark matter
within local substructure can account for this excess, and estimate the
annihilation cross-section for several benchmark minimal supersymmetric (MSSM)
models. We also demonstrate the effect on the permitted parameter space as
tidal stripping effects and destruction of substructure by mergers becomes
increasingly severe.


title:
Supernova Ia and Galaxy Cluster Gas Mass Fraction Constraints on Dark
  Energy

abstract:
  We use the Riess et al.(2004) supernova Ia apparent magnitude versus redshift
data and the Allen et al.(2004) galaxy cluster gas mass fraction versus
redshift data to constrain dark energy models. These data provide complementary
constraints that when combined together ignificantly restrict model parameters
and favor lowly-evolving dark energy density models, close to the Einstein
cosmological constant limit of dark energy.


title:
Star Formation Histories of Nearby Elliptical Galaxies. II. Merger
  Remnant Sample

abstract:
  This work presents high $S/N$ spectroscopic observations of a sample of six
suspected merger remnants, selected primarily on the basis of H{\sc i} tidal
debris detections. Single stellar population analysis of these galaxies
indicates that their ages, metallicities, and $\alpha$-enhancement ratios are
consistent with those of a representative sample of nearby elliptical galaxies.
The expected stellar population of a recent merger remnant, young age combined
with low [$\alpha$/Fe], is not seen in any H{\sc i}-selected galaxy. However,
one galaxy (NGC~2534), is found to deviate from the $Z$-plane in the sense
expected for a merger remnant. Another galaxy (NGC~7332), selected by other
criteria, best matches the merger remnant expectations.


title: OVI Observations of Galaxy Clusters: Evidence for Modest Cooling Flows

abstract:
  A prediction of the galaxy cluster cooling flow model is that as gas cools
from the ambient cluster temperature, emission lines are produced in gas at
subsequently decreasing temperatures. Gas passing through 10^5.5 K emits in the
lines of OVI 1032,1035, and here we report a FUSE study of these lines in three
cooling flow clusters, Abell 426, Abell 1795, and AWM 7. No emission was
detected from AWM 7, but OVI is detected from the centers of Abell 426 and
Abell 1795, and possibly to the south of the center in Abell 1795, where X-ray
and optical emission line filaments lie. In Abell 426, these line luminosities
imply a cooling rate of 32+/-6 Msolar/yr within the central r = 6.2 kpc region,
while for Abell 1795, the central cooling rate is 26+/-7 Msolar/yr (within r =
22 kpc), and about 42+/-9 Msolar/yr including the southern pointing. Including
other studies, three of six clusters have OVI emission, and they also have star
formation as well as emission lines from 1E4 K gas. These observations are
generally consistent with the cooling flow model but at a rate closer to 30
Msolar/yr than originally suggested values of 100-1000 Msolar/yr.


title: The X-Ray Luminosity--Mass Relation for Local Clusters of Galaxies

abstract:
  We investigate the relationship between soft \xray luminosity and mass for
low redshift clusters of galaxies by comparing observed number counts to
expectations of $\Lambda$CDM cosmologies. We use a three-parameter model for
the conditional probability of luminosity given mass and epoch, described as a
log-normal distribution of fixed width centered on a power-law scaling
relation, $L \spropto M^p\rhoc^s(z)$. We use an ensemble of simulated clusters
to argue that the observed, intrinsic variance in the temperature--luminosity
relation is directly indicative of mass--luminosity variance, and derive $\sigm
\se 0.43 \pm 0.06$ from HIFLUGCS data. Adding this to the likelihood analysis
results in best-fit estimates $p \se 1.59 \pm 0.05$, $\lnlf \se 1.34 \pm 0.09$,
and $\sigm \se 0.37 \pm 0.05$ for self-similar redshift evolution in a
concordance ($\Omega_m \se 0.3$, $\Omega_\Lambda \se 0.7$, $\sigma_8 \se0.9$)
universe. We show that the present-epoch intercept is very sensitive to power
spectrum normalization, $\lnlf \spropto \sigate^{-4}$, and the slope is weakly
sensitive to the matter density, $p \spropto \Omega_m^{1/2}$. The intercept
derived here is dimmer by a factor 2, and slope slightly steeper, than the L-M
relation published using hydrostatic mass estimates of the HIFLUGCS sample. We
show that this discrepancy is largely due to Malmquist bias of the \xray\
flux-limited sample. In light of new WMAP constraints, we discuss the interplay
between parameters and sources of systematic error, and offer a compromise
model with $\Omega_m \se 0.24$, $\sigma_8 \se 0.85$, and somewhat lower scatter
$\sigm \se 0.25$, in which hydrostatic mass estimates remain accurate to $\ssim
15%$. We stress the need for independent calibration of the L-M relation via
weak gravitational lensing.


title:
EGRET Excess of diffuse Galactic Gamma Rays interpreted as a Signal of
  Dark Matter Annihilation

abstract:
  Elsaesser and Mannheim fit a contribution of Dark Matter Annihilation (DMA)
to the extragalactic contribution of the galactic diffuse gamma ray flux, as
deduced from the EGRET data by Strong, Moskalenko and Reimer.They find a WIMP
mass of 515{+110}{-75} GeV and quote a systematic error of 30\%. However, they
do not include large systematic uncertainties from the fact that the
determination of the extragalactic flux (EGF) requires a model for the
subtraction of the Galactic flux from the data.The data used were obtained with
a model without Galactic DM, so one expects additional uncertainty in the
region where DMA contributes. Including a Galactic DMA contribution reduces the
significance and the WIMP mass. The latter then becomes compatible with the
Galactic excess of diffuse gamma rays, which posseses all the properties of DMA
with a much higher significance than the extragalactic excess.


title: The 2.5 m Telescope of the Sloan Digital Sky Survey

abstract:
  We describe the design, construction, and performance of the Sloan Digital
Sky Survey Telescope located at Apache Point Observatory. The telescope is a
modified two-corrector Ritchey-Chretien design which has a 2.5-m, f/2.25
primary, a 1.08-m secondary, a Gascoigne astigmatism corrector, and one of a
pair of interchangeable highly aspheric correctors near the focal focal plane,
one for imaging and the other for spectroscopy. The final focal ratio is f/5.
The telescope is instrumented by a wide-area, multiband CCD camera and a pair
of fiber-fed double spectrographs. Novel features of the telescope include: (1)
A 3 degree diameter (0.65 m) focal plane that has excellent image quality and
small geometrical distortions over a wide wavelength range (3000 to 10,600
Angstroms) in the imaging mode, and good image quality combined with very small
lateral and longitudinal color errors in the spectroscopic mode. The unusual
requirement of very low distortion is set by the demands of
time-delay-and-integrate (TDI) imaging; (2) Very high precision motion to
support open loop TDI observations; and (3) A unique wind baffle/enclosure
construction to maximize image quality and minimize construction costs. The
telescope had first light in May 1998 and began regular survey operations in
2000.


title: A Hybrid N-body--Coagulation Code for Planet Formation

abstract:
  We describe a hybrid algorithm to calculate the formation of planets from an
initial ensemble of planetesimals. The algorithm uses a coagulation code to
treat the growth of planetesimals into oligarchs and explicit N-body
calculations to follow the evolution of oligarchs into planets. To validate the
N-body portion of the algorithm, we use a battery of tests in planetary
dynamics. Several complete calculations of terrestrial planet formation with
the hybrid code yield good agreement with previously published calculations.
These results demonstrate that the hybrid code provides an accurate treatment
of the evolution of planetesimals into planets.


title: Reionization on ice

abstract:
  The case for substantial far infrared ice emission in local ultraluminous
infrared galaxies, expected based on the presence of mid-infrared ice
absorption in their spectra and the known far infrared optical properties of
ice, is still largely unsupported by direct observation owing to insufficient
far infrared spectral coverage. Some marginal supportive evidence is presented
here.
  A clear consequence of far infrared ice emission is the need to extend the
range of redshifts considered for submillimeter sources. This is demonstrated
via the example of HDF 850.1.
  The solid phase of the ISM during reionization may be dominated by ice, and
this could lead to the presence of reionization sources in submillimeter source
catalogs. Submillimeter sources not detected at 24 micron in the GOODS-N field
are examined. Two candidate reionization sources are identified at 3.6 micron
through possible Gunn-Peterson saturation in the Z band.


title:
Evidence for environment-dependent galaxy Luminosity Function up to
  z=1.5 in the VIMOS-VLT Deep Survey

abstract:
  We measure the evolution of the galaxy Luminosity Function as a function of
large-scale environment up to z=1.5 from the VIMOS-VLT Deep Survey (VVDS) first
epoch data. The 3D galaxy density field is reconstructed using a sample of 6582
galaxies with 17.5 < I_{AB} < 24 and measured spectroscopic redshifts. We split
the sample in four redshift bins up to z=1.5 and in under-dense and over-dense
environments according to the average density contrast \delta=0. There is a
strong dependence of the Luminosity Function (LF) with large-scale environment
up to z=1.2: the LF shape is observed to have a steeper slope in under-dense
environments. We find a continuous brightening of \Delta M* ~0.6 mag from
z=0.25 to z=1.5 both in under-dense and over-dense environments. The rest-frame
B-band luminosity density continuously increases in under-dense environments
from z=0.25 to z=1.5 whereas its evolution in over-dense environments presents
a peak at z~0.9. We interpret the peak by a complex interplay between the
decrease of the star formation rate and the increasing fraction of galaxies at
\delta>0 due to hierarchical growth of structures. As the environmental
dependency of the LF shape is already present at least up to z=1.2, we
therefore conclude that either the shape of the LF is imprinted very early on
in the life of the Universe, a `nature' process, or that `nurture' physical
processes shaping up environment relation have already been efficient earlier
than a look-back time corresponding to 30% of the current age of the Universe.


title:
High-Energy Activity in the Unusually Soft TeV Source HESS J1804-216
  toward the Galactic Center

abstract:
  In recent years, apparent anisotropies in the ~EeV cosmic ray (CR) flux
arriving at Earth from the general direction of the galactic center have been
reported from the analysis of AGASA and SUGAR data. The more recently
commissioned Auger Observatory has not confirmed these results. HESS has now
detected an unusually soft TeV source roughly coincident with the location of
the previously claimed CR anisotropy. In this paper, we develop a model for the
TeV emission from this object, consistent with observations at other
wavelengths, and examine the circumstances under which it might have
contributed to the $\sim$ EeV cosmic ray spectrum. We find that the supernova
remnant G8.7-0.1 can plausibly account for all the known radiative
characteristics of HESS J1804-216, but that it can accelerate cosmic rays only
up to an energy $\sim 10^5$ GeV. On the other hand, the pulsar (PSR J1803-2137)
embedded within this remnant can in principle inject EeV protons into the
surrounding medium, but it cannot account for the broadband spectrum of HESS
J1804-216. We therefore conclude that although G8.7-0.1 is probably the source
of TeV photons originating from this direction, there is no compelling
theoretical motivation for expecting a cosmic ray anisotropy at this location.
However, if G8.7-0.1 is indeed correctly identified with HESS J1804-216, it
should also produce a $\sim$ GeV flux detectable in a one-year all sky survey
by GLAST.


title: Decrease in the orbital period of dwarf nova OY Carinae

abstract:
  We have measured the orbital light curve of dwarf nova OY Carinae on 8
separate occasions between 1997 September and 2005 December. The measurements
were made in white light using CCD photometers on the Mt Canopus 1 m telescope.
The time of eclipse in 2005 December was 168 +- 5 s earlier than that predicted
by the Wood et al.(1989) ephemeris. Using the times of eclipse from our
measurements and the compilation of published measurements by Pratt et al
(1999) we find that the observational data are inconsistent with a constant
period and indicate that the orbital period is decreasing by 5+-1 X 10^-12 s/s.
This is too fast to be explained by gravitational radiation emission. It is
possible that the change is cyclic with a period greater than about 80 years.
This is much longer than typical magnetic activity cycles and may be due to the
presence of a third object in the system. Preliminary estimates suggest that
this is a brown dwarf with mass about 0.016 Msun and orbital radius >= 17 AU.


title:
The 2005 July Superoutburst of the Dwarf Nova 2QZ J021927.9-304545: the
  SU UMa Nature Confirmed

abstract:
  We report on time-resolved photometry of the 2005 July superoutburst of the
dwarf nova, 2QZ J021927.9-304545. The resultant light curves showed conspicuous
superhumps with a period of 0.081113(19) days, confirming the SU UMa nature of
the object. Although we missed the maximum phase of the outburst, the amplitude
of the superoutburst well exceeded 5 mag. This value is slightly larger than
that of typical SU UMa-type dwarf novae. The superhump period decreased as time
elapsed, as can be seen in most SU UMa-type dwarf novae. Based on the archive
of ASAS-3, the recurrence time of a superoutburst of the variable turned out to
be about 400 days. This value is typical of well known SU UMa stars. The
distance to this system was roughly estimated as 370(+20, -60) pc using an
empirical relation.


title: Change of Mass in the Conservative System of Bodies

abstract:
  A problem of mass in macro- and microcosm has been considered from the single
point of view on the basis of the law of conservation of energy. It is shown
that in the conservative (absolutely closed) system all types of motion and
interaction of the bodies are possible only at the expense of the mass defect
of bodies themselves. As the result, their mass becomes less than the initial
rest mass before forming the system. It leads to some change in the energy
balance of the system and it is noticeably manifested in the motion of bodies
in the relativistic velocity region. The accounting of that essentially adds a
customary picture for the motion of bodies in the conservative system.


title: First AU-scale observations of V1647 Ori with VLTI/MIDI

abstract:
  The young eruptive star V1647 Ori was observed with MIDI, the mid-infrared
interferometric instrument at the Very Large Telescope Interferometer (VLTI),
on March 2, 2005. We present the first spectrally resolved interferometric
visibility points for this object. Our results show that (1) the mid-infrared
emitting region is extended, having a size of ~ 7 AU at 10 um; (2) no
signatures of a close companion can be seen; (3) the 8-13 um spectrum exhibits
no obvious spectral features. Comparison with similar observations of Herbig Ae
stars suggests that V1647 Ori probably possesses a disk of moderate flaring. A
simple disk model with T ~ r^{-0.53}, \Sigma ~ r^{-1.5}, M_d = 0.05 M_Sun is
able to fit both the spectral energy distribution and the observed visibility
values simultaneously.


title: X-Ray Observations of SN 1006 with Integral

abstract:
  The remnant of the supernova of 1006 AD, the remnant first showing evidence
for the presence of X-ray synchrotron emission from shock-accelerated
electrons, was observed for ~1000 ksec with INTEGRAL for the study of electron
acceleration to very high energies. The aim of the observation was to
characterize the synchrotron emission, and attempt to detect non-thermal
bremsstrahlung, using the combination of IBIS and JEM-X spatial and spectral
coverage. The source was detected with JEM-X between 2.4 and 8.4 keV bands, and
not detected with either ISGRI or SPI above 20 keV. The ISGRI upper limit is
about a factor of four above current model predictions, but confirms the
presence of steepening in the power-law extrapolated from lower energies (< 4
keV).


title: Intergal field spectroscopy survey of classical LBV stars in M33

abstract:
  Five well-known LBV stars in M33 were observed with the Multi-Pupil Fiber
Spectrograph (MPFS) on the 6-m Russian telescope. We observed LBVs varA, varB,
varC, var2 and var83. In three of them, var2, var83, varB, large-scale nebulae
were found with sizes from 15 pc and larger. The nebula shapes are complex,
like one-side tails or conical nebulae. They all are related to their LBV
stars. In var2 and var83 stars we found radial velocity gradients 15-30 km/s
across their nebulae. The stars varA and varC do not show extended nebulae, but
nebular lines are certainty present in their spectra.


title:
Phase speed of electrostatic waves: The critical parameter for efficient
  electron surfing acceleration

abstract:
  Particle acceleration by means of non-linear plasma wave interactions is of
great topical interest. Accordingly, in this paper we focus on the electron
surfing process. Self-consistent kinetic simulations, using both relativistic
Vlasov and PIC (Particle In Cell) approaches, show here that electrons can be
accelerated to highly relativistic energies (up to 100 m_e c^2) if the phase
speed of the electrostatic wave is mildly relativistic (0.6c to 0.9c for the
magnetic field strengths considered). The acceleration is strong because of
relativistic stabilisation of the nonlinearly saturated electrostatic wave,
seen in both relativistic Vlasov and PIC simulations. An inverse power law
momentum distribution can arise for the most strongly accelerated electrons.
These results are of relevance to observed rapid changes in the radio
synchrotron emission intensities from microquasars, gamma ray bursts and other
astrophysical objects that require rapid acceleration mechanisms for electrons.


title: A New Approach to the Optimal Target Selection Problem

abstract:
  Optimally selecting a subset of targets from a larger catalog is a common
problem in astronomy and cosmology. A specific example is the selection of
targets from an imaging survey for multi-object spectrographic follow-up. We
present a new heuristic algorithm, HYBRID, for this purpose and undertake
detailed studies of its performance. HYBRID combines elements of the simulated
annealing, MCMC and particle-swarm methods and is particularly successful in
cases where the survey landscape has multiple curvature or clustering scales.
HYBRID consistently outperforms the other methods, especially in
high-dimensionality spaces with many extrema. This means many fewer simulations
must be run to reach a given performance confidence level and implies very
significant advantages in solving complex or computationally expensive
optimisation problems.


title: Is HCN a True Tracer of Dense Molecular Gas in LIRGs and ULIRGs?

abstract:
  We present the results of the first HCO+ survey probing the dense molecular
gas content of a sample of 16 luminous and ultraluminous infrared galaxies
(LIRGs and ULIRGs). Previous work, based on HCN(1-0) observations, had shown
that LIRGs and ULIRGs posses a significantly higher fraction of dense molecular
gas compared to normal galaxies. While the picture issued from HCO+ partly
confirms this result, we have discovered an intriguing correlation between the
HCN(1-0)/HCO+(1-0) luminosity ratio and the IR luminosity of the galaxy
(L(IR)). This trend casts doubts on the use of HCN as an unbiased quantitative
tracer of the dense molecular gas content in LIRGs and ULIRGs. A plausible
scenario explaining the observed trend implies that X-rays coming from an
embedded AGN may play a dominant role in the chemistry of molecular gas at
L(IR) > 1e12 Lsun. We discuss the implications of this result for the
understanding of LIRGs, ULIRGs and high redshift gas-rich galaxies.


title: Using H3+ and H2D+ as probes of star-forming regions

abstract:
  The H3+ and H2D+ ions are important probes of the physical and chemical
conditions in regions of the interstellar medium where new stars are forming.
This paper reviews how observations of these species and of heavier ions such
as HCO+ and H3O+ can be used to derive chemical and kinematic properties of
nearby pre-stellar cores, and the cosmic-ray ionisation rate toward more
distant regions of high-mass star formation. Future prospects in the field are
outlined at the end.


title: Asteroseismology of the visual binary 70 Ophiuchi

abstract:
  Convection in stars excites resonant acoustic waves. The frequencies of these
oscillations depend on the sound speed inside the star, which in turn depends
on density, temperature, gas motion, and other properties of the stellar
interior. Therefore, analysis of the oscillations provides an unrivaled method
to probe the internal structure of a star. Solar-like oscillations in the
primary of the visual binary 70 Ophiuchi are investigated. 70 Ophiuchi A was
observed with the Harps spectrograph mounted on the 3.6-m telescope at the ESO
La Silla Observatory (Chile) during 6 nights in July 2004 allowing us to
collect 1758 radial velocity measurements with a standard deviation of about
1.39 m s-1. The power spectrum of the high precision velocity time series
clearly presents several identifiable peaks between 3 and 6 mHz showing
regularity with a large spacing of Delta_nu = 161.7 +- 0.3 uHz. Fourteen
individual modes were identified with amplitudes in the range 11 to 14 cm s-1.


title:
C II abundances in early-type stars: solution to a notorious non-LTE
  problem

abstract:
  We address a long-standing discrepancy between non-LTE analyses of the
prominent C II 4267 and 6578/82 A multiplets in early-type stars. A
comprehensive non-LTE model atom of C II is constructed based on critically
selected atomic data. This model atom is used for an abundance study of six
apparently slow-rotating main-sequence and giant early B-type stars.
High-resolution and high-S/N spectra allow us to derive highly consistent
abundances not only from the classical features but also from up to 18 further
C II lines in the visual - including two so far unreported emission features
equally well reproduced in non-LTE. These results require the stellar
atmospheric parameters to be determined with care. A homogeneous (slightly)
sub-solar present-day carbon abundance from young stars in the solar vicinity
(in associations and in the field) of log C/H +12= 8.29+/-0.03 is indicated.


title: High-Velocity Clouds and the Local Intergalactic Medium

abstract:
  In this article I review recent observations of the gaseous halos of galaxies
and the intergalactic medium at low redshift. In the first part I discuss
distribution, metal content, and physical properties of the Galactic
intermediate- and high-velocity clouds and the hot halo of the Milky Way.
Recent absorption and emission measurements show that the Galaxy's tidal
interaction with the Magellanic Clouds, the infall of low-metallicity gas, as
well as the circulation of gas as part of the galactic fountain contribute to
the observed distribution of gas in the halo of the Milky Way. In the second
part I give a short overview on the circumgalactic gaseous environment of other
nearby spiral galaxies. Multi-wavelength observations demonstrate that neutral
and ionized gaseous halos of galaxies are common, and that they extend deep
into intergalactic space. These studies suggest that the gaseous material
around spiral galaxies is tightly connected to the on-going hierarchical
formation and evolution of these galaxies. In the last part of this article I
summarize recent quasar absorption-line measurements of the local intergalactic
medium. In accordance with cosmological simulations, absorption-line studies in
the far-ultraviolet indicate that both the photoionized Ly alpha forest and the
shock-heated warm-hot intergalactic medium harbor a substantial fraction of the
baryons in the local Universe.


title: Scalar potential model of redshift and discrete redshift

abstract:
  On the galactic scale the universe is inhomogeneous and redshift $z$ is
occasionally less than zero. A scalar potential model (SPM) that links the
galaxy scale $z$ to the cosmological scale $z$ of the Hubble Law is postulated.
Several differences among galaxy types suggest that spiral galaxies are Sources
and that early type, lenticular, and irregular galaxies are Sinks of a scalar
potential field. The morphology-radius and the intragalactic medium cluster
observations support the movement of matter from Source galaxies to Sink
galaxies. A cell structure of galaxy groups and clusters is proposed to resolve
a paradox concerning the scalar potential like the Olber's paradox concerning
light. For the sample galaxies, the ratio of the luminosity of Source galaxies
to the luminosity of Sink galaxies approaches $2.7 \pm 0.1$. An equation is
derived from sample data, which is anisotropic and inhomogeneous, relating $z$
of and the distance $D$ to galaxies. The calculated $z$ has a correlation
coefficient of 0.88 with the measured $z$ for a sample of 32 spiral galaxies
with $D$ calculated using Cepheid variable stars. The equation is consistent
with $z<0$ observations of close galaxies. At low cosmological distances, the
equation reduces to $z \approx \exp(KD) \, -1 \approx KD$, where $K$ is a
constant, positive value. The equation predicts $z$ from galaxies over 18 Gpc
distant approaches a constant value on the order of 500. The SPM of $z$
provides a physical basis for the $z$ of particle photons. Further, the SPM
qualitatively suggests the discrete variations in $z$, which was reported by W.
G. Tifft, 1997, Astrophy. J. 485, 465 and confirmed by others, are consistent
with the SPM.


title:
Cosmological Gravitational Wave Background from Phase Transitions in
  Neutron Stars

abstract:
  It has recently been suggested that collapse of neutron stars induced by a
phase transition to quark matter can be a considerable source of gravitational
waves with kHz frequencies. We demonstrate that if about one percent of all
neutron stars undergo this process, the resulting cosmological gravitational
wave background would reach about 10^-10 times the critical density. The
background would peak at kHz frequencies and could have an observationally
significant tail down to Hz frequencies. It would be comparable or higher than
other astrophysical backgrounds, for example, from ordinary core collapse
supernovae, from r-mode instabilities in rapidly rotating neutron stars, or
from magnetars. The scenario is consistent with cosmological backgrounds in
neutrinos and photons.


title:
Comparison of Fourier and model-based estimators in single mode
  multiaxial interferometry

abstract:
  There are several solutions to code the signal arising from optical long
baseline multi-aperture interferometers. In this paper,we focus on the {\bf non
homothetic spatial coding scheme} (multiaxial) with the fringe pattern coded
along one dimension on one detector(all-in-one). After describing the physical
principles governing single mode interferometers using that sort of
recombination scheme, we analyze two different existing methods that measure
the source visibility. The first technique, so-called Fourier estimator,
consists in integrating the high frequency peak of the power spectral density
of the interferogram. The second method, so-called model-based estimator, has
been specifically developed for the AMBER instrument of the VLTI and deals with
directly modelling the interferogram recorded on the detector. Performances of
both estimators are computed in terms of Signal to Noise Ratio (SNR) of the
visibility, assuming that the interferograms are perturbed by photon and
detector noises. Theoretical expressions of the visibility SNR are provided,
validated through numerical computations and then compared. We show that the
model-based estimator offers up to 5 times better performances than the Fourier
one.


title: The progenitor set of present-day early-type galaxies

abstract:
  We present a comprehensive theoretical study, within a fully realistic
semi-analytical framework, of the photometric properties of early-type
progenitors in the redshift range 0<z<1, as a function of the luminosity and
local environment of the early-type remnant at present-day. We find that,
averaging across all environments at z~1, less than 50 percent of the stellar
mass which ends up in early-types today is actually in early-type progenitors
at this redshift. The corresponding value is ~65 percent in clusters due to
faster morphological transformations in the such dense environments. We develop
probabilistic prescriptions which provide a means of including spiral (i.e. non
early-type) progenitors at intermediate and high redshifts, based on their
luminosity and optical (BVK) colours. For example, at intermediate redshifts
(z~0.5), large (M_B<-21.5), red (B-V>0.7) spirals have ~75-95 percent chance of
being a progenitor, while the corresponding probability for large blue spirals
(M_B<-21.5, B-V<0.7) is ~50-75 percent. Finally, we explore the correspondence
between the true progenitor set of present-day early-types and the commonly
used `red-sequence', defined as the set of galaxies within the part of the
colour-magnitude space which is dominated by early-type objects. While large
members (M_V<-22) of the `red sequence' trace the progenitor set accurately in
terms of numbers and mass, the relationship breaks down severely at fainter
luminosities (M_V>-21). Hence the red sequence is generally not a good proxy
for the progenitor set of early-type galaxies.


title:
Evidence for strange stars from joint observation of harmonic absorption
  bands and of redshift

abstract:
  From recent reports on terrestrial heavy ion collision experiments it appears
that one may not obtain information about the existence of asymptotic freedom
(AF) and chiral symmetry restoration (CSR) for quarks of QCD at high density.
This information may still be obtained from compact stars - if they are made up
of strange quark matter. Very high gravitational redshift lines (GRL), seen
from some compact stars, seem to suggest high ratios of mass and radius (M/R)
for them. This is suggestive of strange stars (SS) and can in fact be fitted
very well with SQM equation of state deduced with built in AF and CSR. In some
other stars broad absorption bands appear at about ~ 0.3 keV and multiples
thereof, that may fit in very well with resonance with harmonic compressional
breathing mode frequencies of these SS. Emission at these frequencies are also
observed in six stars. If these two features of large GRL and BAB were observed
together in a single star, it would strengthen the possibility for the
existence of SS in nature and would vindicate the current dogma of AF and CSR
that we believe in QCD. Recently, in 4U 1700-24, both features appear to be
detected, which may well be interpreted as observation of SS - although the
group that analyzed the data did not observe this possibility. We predict that
if the shifted lines, that has been observed, are from neon with GRL shift z =
0.4 - then the compact object emitting it is a SS of mass 1.2 M_sun and radius
7 km. In addition the fit to the spectrum leaves a residual with broad dips at
0.35 keV and multiples thereof, as in 1E1207-5209 which is again suggestive of
SS.


title: Dark energy and dark matter as curvature effects

abstract:
  Astrophysical observations are pointing out huge amounts of dark matter and
dark energy needed to explain the observed large scale structures and cosmic
accelerating expansion. Up to now, no experimental evidence has been found, at
fundamental level, to explain such mysterious components. The problem could be
completely reversed considering dark matter and dark energy as shortcomings of
General Relativity and claiming for the correct theory of gravity as that
derived by matching the largest number of observational data. As a result,
accelerating behavior of cosmic fluid and rotation curves of spiral galaxies
are reproduced by means of curvature effects.


title:
Star Formation and Feedback in Smoothed Particle Hydrodynamic
  Simulations--I. Isolated Galaxies

abstract:
  We present an analysis of star formation and feedback recipes appropriate for
galactic smoothed particle hydrodynamics simulations. Using an isolated Milky
Way-like galaxy, we constrain these recipes based on well-established
observational results. Our star formation recipe is based on that of Katz
(1992) with the additional inclusion of physically motivated supernova feedback
recipes. We propose a new feedback recipe in which type II supernovae are
modelled using an analytical treatment of blastwaves. With this feedback
mechanism and a tuning of other star formation parameters, the star formation
in our isolated Milky Way-like galaxy is constant and follows the slope and
normalisation of the observed Schmidt law. In addition, we reproduce the low
density cutoff and filamentary structure of star formation observed in disk
galaxies. Our final recipe will enable better comparison of cosmological N-body
simulations with observations.


title: Forming Disk Galaxies in Lambda CDM Simulations

abstract:
  We used fully cosmological, high resolution N-body + SPH simulations to
follow the formation of disk galaxies with rotational velocities between 135
and 270 km/sec in a Lambda CDM universe. The simulations include gas cooling,
star formation, the effects of a uniform UV background and a physically
motivated description of feedback from supernovae. The host dark matter halos
have a spin and last major merger redshift typical of galaxy sized halos as
measured in recent large scale N--Body simulations. The simulated galaxies form
rotationally supported disks with realistic exponential scale lengths and fall
on both the I-band and baryonic Tully Fisher relations. An extended stellar
disk forms inside the Milky Way sized halo immediately after the last major
merger. The combination of UV background and SN feedback drastically reduces
the number of visible satellites orbiting inside a Milky Way sized halo,
bringing it in fair agreement with observations. Our simulations predict that
the average age of a primary galaxy's stellar population decreases with mass,
because feedback delays star formation in less massive galaxies. Galaxies have
stellar masses and current star formation rates as a function of total mass
that are in good agreement with observational data. We discuss how both high
mass and force resolution and a realistic description of star formation and
feedback are important ingredients to match the observed properties of
galaxies.


title: The Orbit and Occultations of KH 15D

abstract:
  The unusual flux variations of the pre-main-sequence binary star KH 15D have
been attributed to occultations by a circumbinary disk. We test whether or not
this theory is compatible with newly available data, including recent radial
velocity measurements, CCD photometry over the past decade, and photographic
photometry over the past 50 years. We find the model to be successful, after
two refinements: a more realistic motion of the occulting feature, and a halo
around each star that probably represents scattering by the disk. The occulting
feature is exceptionally sharp-edged, raising the possibility that the dust in
the disk has settled into a thin layer, and providing a tool for fine-scale
mapping of the immediate environment of a T Tauri star. However, the window of
opportunity is closing, as the currently visible star may be hidden at all
orbital phases by as early as 2008.


title: Black Holes and Nuclear Dynamics

abstract:
  Supermassive black holes inhabit galactic nuclei, and their presence
influences in crucial ways the evolution of the stellar distribution. The
low-density cores observed in bright galaxies are probably a result of black
hole infall, while steep density cusps like those at the Galactic center are a
result of energy exchange between stars moving in the gravitational field of
the single black hole. Loss-cone dynamics are substantially more complex in
galactic nuclei than in collisionally-relaxed systems like globular clusters
due to the wider variety of possible geometries and orbital populations. The
rate of star-black hole interactions has begun to be constrained through
observations of energetic events associated with stellar tidal disruptions.


title:
A transient I band excess in the optical spectrum of the accreting
  millisecond pulsar SAX J1808.4-3658

abstract:
  The optical counterpart of the transient, millisecond X-ray pulsar SAX
J1808.4-3658 was observed in four colours (BVRI) for five weeks during the 2005
June-July outburst. The optical fluxes declined by ~2 magnitudes during the
first 16 days and then commenced quasi-periodic secondary outbursts, with
time-scales of several days, similar to those seen in 2000 and 2002. The
broadband spectra derived from these measurements were generally consistent
with emission from an X-ray heated accretion disc. During the first 16 days
decline in intensity the spectrum became redder. We suggest that the primary
outburst was initiated by a viscosity change driven instability in the inner
disc and note the contrast with another accreting millisecond pulsar, XTE
J0929--314, for which the spectrum becomes bluer during the decline. On the
night of 2005 June 5 (HJD 2453527) the I band flux was ~0.45 magnitudes
brighter than on the preceding or following nights whereas the BVR bands showed
no obvious enhancement. A Type I X-ray burst was detected by the RXTE
spacecraft during this I band integration. It seems unlikely that reprocessed
radiation from the burst was sufficient to explain the observed increase. We
suggest that a major part of the I band excess was due to synchrotron emission
triggered by the X-ray burst. Several other significant short duration changes
in V-I were detected. One occurred at about HJD 2453546 in the early phase of
the first secondary outburst and may be due to a mass transfer instability or
to another synchrotron emission event.


title:
Radio and X-ray observations of an exceptional radio flare in the
  extreme z=4.72 blazar GB B1428+4217

abstract:
  We report on the extreme behaviour of the high redshift blazar GB B1428+4217
at z=4.72. A continued programme of radio measurements has revealed an
exceptional flare in the lightcurve, with the 15.2 GHz flux density rising by a
factor ~3 from ~140 mJy to ~430 mJy in a rest-frame timescale of only ~4 months
-- much larger than any previous flares observed in this source. In addition to
new measurements of the 1.4-43 GHz radio spectrum we also present the analysis
and results of a target-of-opportunity X-ray observation using XMM-Newton, made
close to the peak in radio flux. Although the X-ray data do not show a flare in
the high energy lightcurve, we are able to confirm the X-ray spectral
variability hinted at in previous observations. GB B1428+4217 is one of several
high-redshift radio-loud quasars that display a low energy break in the X-ray
spectrum, probably due to the presence of excess absorption in the source.
X-ray spectral analysis of the latest XMM-Newton data is shown to be consistent
with the warm absorption scenario which we have hypothesized previously. Warm
absorption is also consistent with the observed X-ray spectral variability of
the source, in which the spectral changes can be successfully accounted-for
with a fixed column density of material in which the ionization state is
correlated with hardness of the underlying power-law emission.


title: Retroduction, Multiverse Hypotheses and Their Testability

abstract:
  The actual existence of collections of universes -- multiverses -- is
strongly suggested by leading approaches to quantum cosmology, and has been
proposed earlier as an attractive way to explain the apparent fine-tuned
character of our universe. But, how can such hypotheses be tested? After
briefly discussing the key distinction between possible and really existing
multiverses, and the importance of an adequate generating process, we focus on
elaborating how multiverse hypotheses can be retroductively tested, even though
they will probably never be directly observed.In this approach, scientific
acceptance of multiverses would rely on the long-term success and fertility of
quantum cosmological theories including them as essential elements or as
inevitable consequences.


title:
Influences of magnetic coupling process on the spectrum of a disk
  covered by the corona

abstract:
  Recently, much attention has been paid to the magnetic coupling (MC) process,
which is supported by very high emissivity indexes observed in Seyfert 1 galaxy
MCG-6-30-15 and GBHC XTE J1650-500. But the rotational energy transferred from
a black hole is simply assumed to be radiated away from the surrounding
accretion disk in black-body spectrum, which is obviously not consistent with
the observed hard power-law X-ray spectra. We intend to introduce corona into
the MC model to make it more compatible with the observations. We describe the
model and the procedure of a simplified Monte Carlo simulation, compare the
output spectra in the cases with and without the MC effects, and discuss the
influences of three parameters involved in the MC process on the output
spectra. It is shown that the MC process augments radiation fluxes in the UV or
X-ray band. The emergent spectrum is affected by the BH spin and magnetic field
strength at the BH horizon, while it is almost unaffected by the radial profile
of the magnetic field at the disk. Introducing corona into the MC model will
improve the fitting of the output spectra from AGNs and GBHCs.


title:
General Relativistic, Neutrino-Assisted MHD winds - Theory and
  Application to GRBs. I. Schwarzschild Geometry

abstract:
  (short version) - A model for GRMHD disk outflows with neutrino-driven mass
ejection is developed,and employed to calculate the structure of the outflow in
the sub-slow magnetosonic region and the mass loading of the outflow, under
conditions anticipated in the central engines of gamma-ray bursts. The
dependence of the mass flux on the conditions in the disk, on magnetic field
geometry, and on other factors is carefully examined for a range of neutrino
luminosities expected in hyperaccreting black holes. The fraction of neutrino
luminosity that is being converted to kinetic energy flux is shown to be a
sensitive function of the effective neutrino temperature at the flow injection
point, and the shape of magnetic field lines in the sub-slow region, but is
practically independent of the strength of poloidal and toroidal magnetic
fields. We conclude that magnetic launching of ultra-relativistic polar
outflows from the innermost parts of the disk is in principle possible provided
the neutrino luminosity is sufficiently low, $L_\nu\simlt10^{52}$ erg s$^{-1}$
or so. The conditions found to be optimal for the launching of an
ultra-relativistic jet are also the conditions favorable for large
neutron-to-proton ratio in the disk.


title:
Magnetars as persistent hard X-ray sources: INTEGRAL discovery of a hard
  tail in SGR 1900+14

abstract:
  Using 2.5 Ms of data obtained by the INTEGRAL satellite in 2003-2004, we
discovered persistent hard X-ray emission from the soft gamma-ray repeater SGR
1900+14. Its 20-100 keV spectrum is well described by a steep power law with
photon index Gamma=3.1+/-0.5 and flux 1.5E-11 erg/cmsq/s. Contrary to SGR
1806-20, the only other soft gamma-ray repeater for which persistent emission
above 20 keV was reported, SGR 1900+14 has been detected in the hard X-ray
range while it was in a quiescent state (the last bursts from this source were
observed in 2002). By comparing the broad band spectra (1-100 keV) of all the
magnetars detected by INTEGRAL (the two SGRs and three anomalous X-ray pulsars)
we find evidence for a different spectral behaviour of these two classes of
sources.


title: A 2 mm spectral line survey of the starburst galaxy NGC 253

abstract:
  We present the first unbiased molecular line survey towards an extragalactic
source, namely the nuclear region of the starburst galaxy NGC 253. The scan
covers the frequency band from 129.1 to 175.2 GHz, i.e. most of the 2mm
atmospheric window. We identify 111 spectral features as transitions from 25
different molecular species. Eight of which (three tentatively) are detected
for the first time in the extragalactic interstellar medium. Among these newly
detected species, we detected the rare isotopomers 34SO and HC18O+. Tentative
detections of two deuterated species, DNC and N2D+, are reported for the first
time from a target beyond the Magellanic Clouds. Additionally, three hydrogen
recombination lines are identified, while no organic molecules larger than
methanol are detected. Column densities and rotation temperatures are
calculated for all the species, including an upper limit to the ethanol
abundance. A comparison of the chemical composition of the nuclear environment
of NGC 253 with those of selected nearby galaxies demonstrates the chemical
resemblance of IC 342 and NGC 4945 to that of NGC 253. On the other hand, the
chemistries characterizing NGC 253 and M 82 are clearly different. We also
present a comparison of the chemical composition of NGC 253 with those observed
in Galactic prototypical sources. The chemistry of NGC 253 shows a striking
similarity with the chemistry observed toward the Galactic center molecular
clouds, which are thought to be dominated by low-velocity shocks. This
resemblance strongly suggests that the heating in the nuclear environment of
NGC 253 is dominated by the same mechanism as that in the central region of the
Milky Way.


title: Modeling the QSO luminosity and spatial clustering at low redshifts

abstract:
  We investigate the ability of hierarchical models of QSO formation and
evolution to match the observed luminosity, number counts and spatial
clustering of quasars at redshift z<2. These models assume that the QSO
emission is triggered by galaxy mergers, that the mass of the central black
hole correlates with halo properties and that quasars shine at their Eddington
luminosity except, perhaps, during the very early stages of evolution. We find
that models based on simple analytic approximations successfully reproduce the
observed B-band QSO luminosity function at all redshifts, provided that some
mechanisms is advocated to quench mass accretion within haloes larger than
about 1e13 Msun that host bright quasars. These models also match the observed
strength of QSO clustering at z~0.8. At larger redshifts, however, they
underpredict the QSO biasing which, instead, is correctly reproduced by
semi-analytic models in which the halo merger history and associated BHs are
followed by Monte Carlo realizations of the merger hierarchy. We show that the
disagreement between the luminosity function predicted by semi-analytic models
and observations can be ascribed to the use of B-band data, which are a biased
tracer of the quasar population, due to obscuration.


title: Validation of stellar population and kinematical analysis of galaxies

abstract:
  3D spectroscopy produces hundreds of spectra from which maps of the
characteristics of stellar populations (age-metallicity) and internal
kinematics of galaxies can be derived. We carried on simulations to assess the
reliability of inversion methods and to define the requirements for future
observations. We quantify the biases and show that to minimize the errors on
the kinematics, age and metallicity (in a given observing time) the size of the
spatial elements and the spectral dispersion should be chosen to obtain an
instrumental velocity dispersion comparable to the physical dispersion.


title:
Formation of Supermassive Black Holes by Direct Collapse in Pregalactic
  Halos

abstract:
  We describe a mechanism by which supermassive black holes can form directly
in the nuclei of protogalaxies, without the need for seed black holes left over
from early star formation. Self-gravitating gas in dark matter halos can lose
angular momentum rapidly via runaway, global dynamical instabilities, the
so-called "bars within bars" mechanism. This leads to the rapid buildup of a
dense, self-gravitating core supported by gas pressure - surrounded by a
radiation pressure-dominated envelope - which gradually contracts and is
compressed further by subsequent infall. These conditions lead to such high
temperatures in the central region that the gas cools catastrophically by
thermal neutrino emission, leading to the formation and rapid growth of a
central black hole.
  We estimate the initial mass and growth rate of the black hole for typical
conditions in metal-free halos with T_vir ~ 10^4 K, which are the most likely
to be susceptible to runaway infall. The initial black hole should have a mass
of <~20 solar masses, but in principle could grow at a super-Eddington rate
until it reaches ~ 10^4-10^6 solar masses. Rapid growth may be limited by
feedback from the accretion process and/or disruption of the mass supply by
star formation or halo mergers. Even if super-Eddington growth stops at
\~10^3-10^4 solar masses, this process would give black holes ample time to
attain quasar-size masses by a redshift of 6, and could also provide the seeds
for all supermassive black holes seen in the present universe.


title:
Enigma of ultraluminous X-ray sources may be resolved by 3D-spectroscopy
  (MPFS data)

abstract:
  The ultraluminous X-ray sources (ULXs) were isolated in external galaxies for
the last 5 years. Their X-ray luminosities exceed 100-10000 times those of
brightest Milky Way black hole binaries and they are extremely variable. There
are two models for the ULXs, the best black hole candidates. 1. They are
supercritical accretion disks around a stellar mass black hole like that in
SS433, observed close to the disk axes. 2. They are Intermediate Mass Black
Holes (of 100-10000 solar masses). Critical observations which may throw light
upon the ULXs nature come from observations of nebulae around the ULXs. We
present results of 3D-spectroscopy of nebulae around several ULXs located in
galaxies at 3-6 Mpc distances. We found that the nebulae to be powered by their
central black holes. The nebulae are shocked and dynamically perturbed probably
by jets. The nebulae are compared with SS433 nebula (W50).


title:
Resonance-Enhanced Two-Photon Ionization (RETPI) of SiII and an
  Anomalous, Variable Intensity of the 1892A SiIII] Line in the Weigelt Blobs
  of Eta Carinae

abstract:
  The Si III] 1892A intercombination line shows an anomalously high intensity
in spectra of the radiation-rich Weigelt blobs in the vicinity of Eta Carinae.
The line disappears during the 100 days long spectral events occurring every
5.5 years. The aim is to investigate whether resonance-enhanced two-photon
ionization (RETPI) is a plausible excitation mechanism for the Si III] 1892A
line. The possible intensity enhancement of the 1892A line is investigated as
regards quasi-resonant intermediate energy levels of Si II. The RETPI mechanism
is effective on SiII in the radiation-rich Weigelt blobs where the two
excitation steps are provided by the two intense hydrogen lines Ly alpha and Ly
gamma


title: Clumpy winds and the obscuration of Active Galactic Nuclei

abstract:
  The role of star-formation driven outflows in the obscuration of the central
source in the Active Galactic Nuclei (AGN) is discussed. The outflow from a
sub-parsec scale accretion disc is numerically modelled for parameters
appropriate to the Galactic Centre. The resulting obscuration pattern is very
patchy, with some lines of sight becoming optically thick to Thomson
scattering. A fixed observer would see column depth changing by factors of many
over time scales of order months to hundreds of years, depending on the
physical size of the outflow region. Such winds may be relevant for obscuration
of some AGN and especially "changing look AGN". However, averaged over the sky
as seen from the central source, these winds are always optically thin unless
wind outflow rates are super-Eddington. A simple scaling argument shows that
this is true not only for stellar-driven winds but for any AGN winds. We
therefore conclude that AGN winds are unable to account for the vast majority
of optically thick obscured AGN (a significant fraction of all AGN). We suggest
that the most likely source of optically thick obscuration in AGN is a warped
parsec scale accretion disc.


title: PPV Chapter - The Formation of Brown Dwarfs

abstract:
  We review five mechanisms for forming brown dwarfs: (i) turbulent
fragmentation of molecular clouds, producing very low-mass prestellar cores by
shock compression; (ii) collapse and fragmentation of more massive prestellar
cores; (iii) disc fragmentation; (iv) premature ejection of protostellar
embryos from their natal cores; and (v) photo-erosion of pre-existing cores
overrun by HII regions. These mechanisms are not mutually exclusive. Their
relative importance probably depends on environment, and should be judged by
their ability to reproduce the brown-dwarf IMF, the distribution and kinematics
of newly formed brown dwarfs, the binary statistics of brown dwarfs, the
ability of brown dwarfs to retain discs, and hence their ability to sustain
accretion and outflows. This will require more sophisticated numerical
modelling than is presently possible, in particular more realistic initial
conditions and more realistic treatments of radiation transport, angular
momentum transport and magnetic fields. We discuss the minimum mass for brown
dwarfs, and how brown dwarfs should be distinguished from planets.


title: A Simple Model for Lensing by Black Holes in Galactic Nuclei

abstract:
  The lensing properties of the Plummer model with a central point mass and
external shear are derived, including the image multiplicities, critical curves
and caustics. This provides a simple model for a flattened galaxy with a
central supermassive black hole. For the Plummer model with black hole, the
maximum number of images is 4, provided the black hole mass is less than an
upper bound which is calculated analytically. This introduces a method to
constrain black hole masses by counting images, thus applicable at cosmological
distance. With shear, the maximum number of images is 6 and we illustrate the
occurrence of an astroid caustic and two metamorphoses.


title:
Integral Field Spectroscopy of a peculiar Supernova Remnant MF16 in
  NGC6946

abstract:
  We present a study of a peculiar Supernova Remnant MF16, associated with the
Ultraluminous X-ray Source (ULX) NGC6946 ULX-1. Observations were taken with
the MultiPupil Fiber Spectrograph (MPFS) with 6-m telescope on January 2005.
The nebula is found to be highly asymmetric, one of the parts being much denser
and colder. The two-component structure of the emission lines and radial
velocity gradient argue for a non-spherical nebula, expanding with a velocity
of about 100 km/s. Neither shock models nor the X-ray emission can adequately
explain the actual emission line spectrum of MF16, so we suggest an additional
ultraviolet source with a luminosity of about 10E40 erg/s. We confirm
coincidence of the ULX with the central star, and identify radio emission
observed by VLA with the most dense part of the nebula.


title: Optically Selected GRB Afterglows

abstract:
  Since November 2004, we attempt to detect GRB optical afterglows in near
real-time on images taken at the Canada France Hawaii Telescope within the Very
Wide Survey, component of the CFHT Legacy survey. To do so, a Real Time
Analysis System automatically and quickly analyzes MegaCAM images and extracts
from them a list of photometrically and astrometrically variable objects which
is then validated by a member of the collaboration. Each month, we repeatedly
observe 15 to 30 square degrees down to magnitude i' = 22.5. A few objects are
classified as candidates and analyzed more deeply, and statistics are done
showing the treatment's performance.


title: 2D Models for Dust-driven AGB Star Winds

abstract:
  New axisymmetric (2D) models for dust-driven winds of C-stars are presented
which include hydrodynamics with radiation pressure on dust, equilibrium
chemistry and time-dependent dust formation with coupled grey Monte Carlo
radiative transfer. Considering the most simple case without stellar pulsation
(hydrostatic inner boundary condition) these models reveal a more complex
picture of the dust formation and wind acceleration as compared to earlier
published spherically symmetric (1D) models. The so-called exterior
$\kappa$-mechanism causes radial oscillations with short phases of active dust
formation between longer phases without appreciable dust formation, just like
in the 1D models. However, in 2D geometry, the oscillations can be out-of-phase
at different places above the stellar atmosphere which result in the formation
of dust arcs or smaller caps that only occupy a certain fraction of the total
solid angle. These dust structures are accelerated outward by radiation
pressure, expanding radially and tangentially like mushroom clouds, while
dust-poor matter is falling back towards the star at other places. A highly
dynamical and turbulent dust formation zone is created in this way, which again
leads to inhomogeneous dust production. Further away from the star, flow
instabilities (e.g. Rayleigh-Taylor) have time to fragment the outward moving
arcs and shells to produce numerous small-scale cloud-like sub-structures.


title:
Optical and infrared observations of the Type IIP SN2002hh from day 3 to
  397

abstract:
  We present optical and infrared (IR) observations of the type IIP SN2002hh
from 3 to 397 days after explosion. The optical spectroscopic (4-397d) and
photometric (3-278d) data are complemented by spectroscopic (137-381d) and
photometric (137-314d) data acquired at IR wavelengths. This is the first time
L-band spectra have ever been successfully obtained for a supernova at a
distance beyond the Local Group. The VRI light curves in the first 40 days
reveal SN2002hh to be a SN IIP (plateau) - the most common of all core-collapse
supernovae. SN2002hh is one of the most highly extinguished supernovae ever
investigated. To provide a good match between its early-time spectrum and a
coeval spectrum of the Type IIP SN1999em, as well as maintaining consistency
with KI interstellar absorption, we invoke a 2-component extinction model. One
component is due to the combined effect of the interstellar medium of our Milky
Way Galaxy and the SN host galaxy, while the other component is due to a "dust
pocket" where the grains have a mean size smaller than in the interstellar
medium. The early-time optical light curves of SNe 1999em and 2002hh are
generally well-matched, as are the radioactive tails of these two SNe and
SN1987A. The late-time similarity of the SN2002hh optical light curves to those
of SN1987A, together with measurements of the optical/IR luminosity and [FeII]
1.257mu emission indicate that 0.07 +- 0.02 Msun of Ni 56 was ejected by
SN2002hh. [... ABRIDGED...] From the [OI] 6300,6364 A doublet luminosity we
infer a 16-18 Msun main-sequence progenitor star. The progenitor of SN2002hh
was probably a red supergiant with a substantial, dusty wind.


title: Galaxy cluster mass profiles

abstract:
  Accurate measurements of the mass distribution in galaxy and cluster halos
are essential to test the cold dark matter (CDM) paradigm. The cosmological
model predicts a universal shape for the density profile in all halos,
independent of halo mass. Its profile has a `cuspy' centre, with no evidence
for the constant density core. In this paper we carry out a careful analysis of
twelve galaxy clusters, using Chandra data to compute the mass distribution in
each system under the assumption of hydrostatic equilibrium. Due to their low
concentration, clusters provide ideal objects for studying the central cusps in
dark matter halos. The majority of the systems are consistent with the CDM
model, but 4 objects exhibit flat inner density profiles. We suggest that the
flat inner profile found for these clusters is due to an underestimation of the
mass in the cluster centre (rather than any problem with the CDM model), since
these objects also have a centrally peaked gas mass fraction. We discuss
possible causes for erroneously low mass measurements in the cores of some
systems.


title: Environments of powerful radio galaxies through the cosmic ages

abstract:
  I define 3 samples of extragalactic radio sources of type FRII, containing 26
objects in total. The control sample consists of 6C and 7C sources with
radio-luminosities of around 10E27 W\Hz at 151 MHz and z~1. The other samples
contain 3CRR sources with either comparable redshifts but radio luminosities
about a decade larger or with comparable radio-luminosities but redshifts
around z~0.4. These samples are used to investigate the possible evolution of
depolarisation and rotation measure properties with redshift and radio
luminosity independently. I use the \citet{kat97} model with 3 flux
measurements to estimate the density of the source environment, source age and
jet power. Depolarisation and variations in the rotation measure were found to
be insensitive to changes in the density of the source environment. This
indicates that depolarisation and variations in the rotation measure are not
density indicators but map how the disorder in the magnetic field changes with
redshift. The model is then used on a larger set of FRII sources taken from the
complete 3CRR, 6CE and 7C III samples. I find that the density of the source
environment is a strong function of the source radio-luminosity but is
insensitive to changes in redshift. The jet power is also a strong function of
radio-luminosity but also a weak function of redshift. This indicates that the
mass of the black-hole powering FRII sources is epoch dependent. In general, I
find that the source environment is dominated by changes in the
radio-luminosity but is relatively unaffected by changes in cosmic epoch.


title: Observational constraints on Cosmic Reionization

abstract:
  Recent observations have set the first constraints on the epoch of
reionization (EoR), corresponding to the formation epoch of the first luminous
objects. Studies of Gunn-Peterson (GP) absorption, and related phenomena,
suggest a qualitative change in the state of the intergalactic medium (IGM) at
$z \sim 6$, indicating a rapid increase in the neutral fraction of the IGM,
from $x_{HI} < 10^{-4}$ at $z \le 5.5$, to $x_{HI} > 10^{-3}$, perhaps up to
0.1, at $z \ge 6$. Conversely, transmission spikes in the GP trough, and the
evolution of the \lya galaxy luminosity function indicate $x_{HI} < 0.5$ at
$z\sim 6.5$, while the large scale polarization of the cosmic microwave
background (CMB) implies a significant ionization fraction extending to higher
redshifts, $z \sim 11 \pm 3$. The results suggest that reionization is less an
event than a process, with the process beginning as early as $z \sim 14$, and
with the 'percolation', or 'overlap' phase ending at $z \sim 6$. The data are
consistent with low luminosity star forming galaxies as being the dominant
sources of reionizing photons. Low frequency radio telescopes currently under
construction should be able to make the first direct measurements of HI 21cm
emission from the neutral IGM during the EoR, and upcoming measurements of
secondary CMB temperature anisotropy will provide fine details of the dynamics
of the reionized IGM.


title:
Effervescent heating: constraints from nearby cooling flow clusters
  observed with XMM-Newton

abstract:
  We have used deprojected radial density and temperature profiles of a sample
of 16 nearby CF clusters observed with XMM-Newton to test whether the
effervescent heating model can satisfactorily explain the dynamics of CF
clusters. For each cluster we derived the required extra heating as a function
of cluster-centric distance for various values of the unknown parameters $\dot
M$ (mass deposition rate) and $f_c$ (conduction efficiency). We fitted the
extra heating curve using the AGN effervescent heating function and derived the
AGN parameters $L$ (the time-averaged luminosity) and $r_0$ (the scale radius
where the bubbles start rising in the ICM). While we do not find any solution
with the effervescent heating model for only one object, we do show that AGN
and conduction heating are not cooperating effectively for half of the objects
in our sample. For most of the clusters we find that, when a comparison is
possible, the derived AGN scale radius $r_0$ and the observed AGN jet extension
have the same order of magnitude. The AGN luminosities required to balance
radiative losses are substantially lowered if the fact that the AGN deposits
energy within a finite volume is taken into account. For the Virgo cluster, we
find that the AGN power derived from the effervescent heating model is in good
agreement with the observed jet power.


title: Anisotropic perturbations due to dark energy

abstract:
  A variety of observational tests seem to suggest that the universe is
anisotropic. This is incompatible with the standard dogma based on adiabatic,
rotationally invariant perturbations. We point out that this is a consequence
of the standard decomposition of the stress-energy tensor for the cosmological
fluids, and that rotational invariance need not be assumed, if there is elastic
rigidity in the dark energy. The dark energy required to achieve this might be
provided by point symmetric domain wall network with $P/\rho=-2/3$, although
the concept is more general. We illustrate this with reference to a model with
cubic symmetry and discuss various aspects of the model.


title: Measuring the effective complexity of cosmological models

abstract:
  We introduce a statistical measure of the effective model complexity, called
the Bayesian complexity. We demonstrate that the Bayesian complexity can be
used to assess how many effective parameters a set of data can support and that
it is a useful complement to the model likelihood (the evidence) in model
selection questions. We apply this approach to recent measurements of cosmic
microwave background anisotropies combined with the Hubble Space Telescope
measurement of the Hubble parameter. Using mildly non-informative priors, we
show how the 3-year WMAP data improves on the first-year data by being able to
measure both the spectral index and the reionization epoch at the same time. We
also find that a non-zero curvature is strongly disfavored. We conclude that
although current data could constrain at least seven effective parameters, only
six of them are required in a scheme based on the Lambda-CDM concordance
cosmology.


title:
An Observational Perspective of Low-Mass Dense Cores I: Internal
  Physical and Chemical Properties

abstract:
  Low-mass dense cores represent the state of molecular gas associated with the
earliest phases of low-mass star formation. Such cores are called
"protostellar" or "starless," depending on whether they do or do not contain
compact sources of luminosity. In this chapter, the first half of the review of
low-mass dense cores, we describe the numerous inferences made about the nature
of starless cores as a result of recent observations, since these reveal the
initial conditions of star formation. We focus on the identification of
isolated starless cores and their internal physical and chemical properties,
including morphologies, densities, temperatures, kinematics, and molecular
abundances. These objects display a wide range of properties since they are
each at different points on evolutionary paths from ambient molecular cloud
material to cold, contracting, and centrally concentrated configurations with
significant molecular depletions and, in rare cases, enhancements.


title:
A multi-resolution analysis of the radio-FIR correlation in the Large
  Magellanic Cloud

abstract:
  We investigate the local correlation betwen the 1.4 GHz radio continuum and
60 micron far-infrared (FIR) emission within the Large Magellanic Cloud (LMC)
on spatial scales between 0.05 and 1.5 kpc. On scales below ~1 kpc, the
radio-FIR correlation is clearly better than the correlation of the cold gas
tracers with either the radio or the FIR emission. For the LMC as a whole,
there is a tight correlation between the radio and FIR emission on spatial
scales above ~50 pc. By decomposing the radio emission into thermal and
non-thermal components, however, we show that the scale on which the radio-FIR
correlation breaks down is inversely proportional to the thermal fraction of
the radio emission: regions that show a strong correlation to very small scales
are the same regions where the thermal fraction of the radio emission is high.
Contrary to previous studies of the local radio-FIR correlation in the LMC, we
show that the slope of the relation between the radio and FIR emission is
non-linear. In bright star-forming regions, the radio emission increases faster
than linearly with respect to the FIR emission (power-law slope of ~1.2),
whereas a flatter slope of ~0.6-0.9 applies more generally across the LMC. Our
results are consistent with a scenario in which the UV photons and cosmic rays
in the LMC have a common origin in massive star formation, but the cosmic rays
are able to diffuse away from their production sites. Our results do not
provide direct evidence for coupling between the magnetic field and the local
gas density, but we note that synchrotron emission may not be a good tracer of
the magnetic field if cosmic rays can readily escape the LMC.


title: Muon Flux at the Geographical South Pole

abstract:
  The muon flux at the South-Pole was measured for five zenith angles,
$0^{\circ}$, $15^{\circ}$, $35^{\circ}$, $82.13^{\circ}$ and $85.15^{\circ}$
with a scintillator muon telescope incorporating ice Cherenkov tank detectors
as the absorber. We compare the measurements with other data and with
calculations.


title: Dynamic Alignment in Driven Magnetohydrodynamic Turbulence

abstract:
  Motivated by recent analytic predictions, we report numerical evidence
showing that in driven incompressible magnetohydrodynamic turbulence the
magnetic- and velocity-field fluctuations locally tend to align the directions
of their polarizations. This dynamic alignment is stronger at smaller scales
with the angular mismatch between the polarizations decreasing with the scale
\lambda approximately as \theta_\lambda ~ \lambda^{1/4}. This can naturally
lead to a weakening of the nonlinear interactions and provide an explanation
for the energy spectrum E(k) ~ k^{-3/2} that is observed in numerical
experiments of strongly magnetized turbulence.

categories: astro-ph nlin.CD physics.flu-dyn physics.plasm-ph


title: The Protostellar Jet Model of Chondrule Formation

abstract:
  A chondrule formation theory is presented where the chondrule formation zone
is located within 0.1 AU of the protosun. This hot, optically thick, inner zone
of the solar accretion disk is coincident with the formation region of the
protosolar jet.
  The model assumes that particles, ranging in diameter from 1 micron to 1 cm,
can be ejected from the inner-accretion disk by the jet flow, and that the
angular momentum of this material is sufficient to eject it from the jet flow.
Given these assumptions, any material so ejected, will fly across the face of
the accretion disk at speeds greater than the escape velocity of the system.
This material can only be recaptured through the action of gas drag. Such a
capture process naturally produces aerodynamic size sorting of chondrules and
chondrule fragments, while the ejection of refractory dust provides a possible
explanation for the observed complementarity between matrix and chondrules.
This transfer of material will result in the loss of angular momentum from the
upper atmosphere of the outer accretion disk and thereby facilitate the
accretion of matter onto the protosun.


title: A late, infrared flash from the afterglow of GRB 050319

abstract:
  We report the detection of a bright, near-infrared flash from the afterglow
of GRB 050319, 6.15 hours after the burst. The IR flash faded rapidly from
J=13.12 mag. to J > 15.5 mag. in about 4 minutes. There are no reported
simultaneous observations at other wavelengths making it an unique event. We
study the implications of its late timing in the context of current theoretical
models for GRB afterglows.


title:
Spectroscopy of the brightest optical counterparts of X-ray sources in
  the direction of M~31 and M~33

abstract:
  Recent surveys of the Local Group spiral Galaxies M31 and M33 with XMM-Newton
yielded a large number of X-ray sources. As part of the effort to identify and
classify the objects responsible for this X-ray emission, we have obtained
optical spectra of the brightest optical counterparts of the identified X-ray
sources, using the 1.3m Skinakas Telescope. Most of these objects are
foreground star candidates. The purpose of the present study is to confirm this
identification and to explore the compatibility between the optical spectral
classification and the observed X-ray properties of the sources. We have
obtained optical spectra for the 14 brightest optical counterparts of X-ray
sources identified by XMM-Newton in the direction of M31 and for 21 optical
counterparts in the direction of M33, using the 1.3m Skinakas telescope in
Crete, Greece. All of the M31 sources and all but one of the M33 sources were
confirmed to be foreground stars, of spectral types between A and M. One of the
stars is a late M dwarf with H-alpha emission, a flare star, also displaying
strong X-ray variability. One of the M~33 sources (lying within the D25
ellipse) corresponds to a previously known background galaxy, LEDA 5899.


title:
Star formation feedback and metal enrichment by SN Ia and SN II in dwarf
  spheroidal galaxies: the case of Draco

abstract:
  We present 3D hydrodynamical simulations aimed to study the dynamical and
chemical evolution of the interstellar medium in dwarf spheroidal galaxies.
This evolution is driven by the explosions of Type II and Type Ia supernovae,
whose different contribution is explicity taken into account in our models. We
compare our results with detailed observations of the Draco galaxy. We assume
star formation histories consisting of a number of instantaneous burst
separated by quiescent periods. Because of the large effectiveness of the
radiative losses and the extended dark matter halo, no galactic wind develops,
despite the total energy released by the supernovae is much larger than the
binding energy of the gas. This explains why the galaxy is able to form stars
for a long period (> 3 Gyr), consistently with observations. In this picture,
the end of the star formation and gas removal must result from external
mechanisms, such as ram pressure and/or tidal interaction with the Galaxy. The
metallicity distributions of the stars found in our models agree very well with
the observed one. We find a mean value <[Fe/H]>=-1.65 with a spread of ~1.5
dex. The chemical properties of the stars derive by the different temporal
evolution between Type Ia and Type II supernova rate, and by the different
mixing of the metals produced by the two types of SNe. We reproduce
successfully the observed [O/Fe]-[Fe/H] diagram. However, our interpretation of
this diagram differs from that generally adopted by previous chemical models.
In fact, we find that the chemical properties of the stars derive, besides the
different temporal evolution of the SNe II and SNe Ia rates, from the spatial
inhomogeneous chemical enrichment due to the different dynamical behaviour
between the remnants of the two types of supernovae.


title:
The variable X-ray light curve of GRB 050713A: the case of refreshed
  shocks

abstract:
  We present a detailed study of the spectral and temporal properties of the
X-ray and optical emission of GRB050713a up to 0.5 day after the main GRB
event. The X-ray light curve exhibits large amplitude variations with several
rebrightenings superposed on the underlying three-segment broken powerlaw that
is often seen in Swift GRBs. Our time-resolved spectral analysis supports the
interpretation of a long-lived central engine, with rebrightenings consistent
with energy injection in refreshed shocks as slower shells generated in the
central engine prompt phase catch up with the afterglow shock at later times.
Our sparsely-sampled light curve of the optical afterglow can be fitted with a
single power law without large flares. The optical decay index appears flatter
than the X-ray one, especially at later times.


title: Constraints on Galactic Intermediate Mass Black Holes

abstract:
  Intermediate Mass Black Holes (IMBHs; 10^1.3-5 M_sun) are thought to form as
relics of Population III stars or from the runaway collapse of stars in young
clusters; their number and very existence are uncertain. We ran N-body
simulations of Galactic IMBHs, modelling them as a halo population distributed
according to a Navarro, Frenk & White (NFW) or a more concentrated Diemand,
Madau & Moore (DMM) density profile. As IMBHs pass through Galactic
molecular/atomic hydrogen regions, they accrete gas, thus becoming X-ray
sources. We constrain the density of Galactic IMBHs, Omega_IMBH, by comparing
the distribution of simulated X-ray sources with the observed one. From the
null detections of Milky Way Ultra-Luminous X-ray sources, and from a
comparison of simulations with unidentified sources in the IBIS/ISGRI catalogue
we find a strong upper limit Omega_IMBH <= 10^-2 Omega_b (<= 10^-1 Omega_b) for
a DMM (NFW) profile, if IMBHs accrete via ADAF disks. Slightly stronger
constraints (Omega_IMBH <= 10^-3 Omega_b for a DMM profile; Omega_IMBH <= 10^-2
Omega_b for a NFW profile) can be derived if IMBHs accrete with higher
efficiency, such as by forming thin accretion disks. Although not very tight,
such constraints are the most stringent ones derived so far in the literature.


title:
Rotational mixing in low-mass stars II. Self-consistent models of Pop II
  RGB stars

abstract:
  In this paper we study the effects of rotation in low-mass, low-metallicity
RGB stars. We present the first evolutionary models taking into account
self-consistently the latest prescriptions for the transport of angular
momentum by meridional circulation and shear turbulence in stellar interiors as
well as the associated mixing processes for chemicals computed from the ZAMS to
the upper RGB. We discuss in details the uncertainties associated with the
physical description of the rotational mixing and study carefully their effects
on the rotation profile, diffusion coefficients, structural evolution,
lifetimes and chemical signatures at the stellar surface. We focus in
particular on the various assumptions concerning the rotation law in the
convective envelope, the initial rotation velocity distribution, the presence
of mean molecular weight gradients and the treatment of the horizontal and
vertical turbulence. This exploration leads to two main conclusions : (1) After
the completion of the first dredge-up, the degree of differential rotation (and
hence mixing) is maximised in the case of a differentially rotating convective
envelope (i.e., j_CE(r) = cst), as anticipated in previous studies. (2) Even
with this assumption, and contrary to some previous claims, the present
treatment for the evolution of the rotation profile and associated meridional
circulation and shear turbulence does not lead to enough mixing of chemicals to
explain the abundance anomalies in low-metallicity field and globular cluster
RGB stars observed around the bump luminosity. This study raises questions that
need to be addressed in a near future. These include for example the
interaction between rotation and convection and the trigger of additional
hydrodynamical instabilities.


title: A search for water masers toward extrasolar planets

abstract:
  Water is the most common triatomic molecule in the universe and the basis of
life on Earth. Astrophysical masers have been widely studied in recent years
and have been shown to be invaluable probes of the details of the environment
in which they are found. Water masers, for instance, are often detected toward
low-mass star-forming regions. Doppler radial-velocity surveys have detected
about 160 exoplanets. Observations of water masers from exoplanetary systems
would give us a new detailed window through which to explore them. We present a
search for water masers toward eighteen extrasolar planets using the newly
upgraded Australia Telescope Compact Array at 12 mm. A sensitivity of about 25
mJy/beam and an angular resolution of about 10'' were achieved at 22.235 GHz.
No maser lines are clearly observed.


title:
Recent progress of avalanche photodiodes in high-resolution X-rays and
  Gamma-rays detection

abstract:
  We have studied the performance of large area avalanche photodiodes (APDs)
recently developed by Hamamatsu Photonics K.K, in high-resolution X-rays and
Gamma-rays detections. We show that reach-through APD can be an excellent soft
X-ray detector operating at room temperature or moderately cooled environment.
We obtain the best energy resolution ever achieved with APDs, 6.4 % for 5.9 keV
X-rays, and obtain the energy threshold as low as 0.5 keV measured at -20deg.
Thanks to its fast timing response, signal carriers in the APD device are
collected within a short time interval of 1.9 nsec (FWHM). This type of APDs
can therefore be used as a low-energy, high-counting particle monitor onboard
the forthcoming Pico-satellite Cute1.7. As a scintillation photon detector,
reverse-type APDs have a good advantage of reducing the dark noise
significantly. The best FWHM energy resolutions of 9.4+-0.3 % and 4.9+-0.2 %
were obtained for 59.5 keV and 662 keV Gamma-rays, respectively, as measured
with a CsI(Tl) crystal. Combination of APDs with various other scintillators
(BGO, GSO, and YAP) also showed better results than that obtained with a
photomultiplier tube (PMT). These results suggest that APD could be a promising
device for replacing traditional PMT usage in some applications. In particular
2-dim APD array, which we present in this paper, will be a promising device for
a wide-band X-ray and Gamma-ray imaging detector in future space research and
nuclear medicine.


title:
An Active Gain-control System for Avalanche Photo-Diodes under Moderate
  Temperature Variations

abstract:
  Avalanche photodiodes (APDs) are promising light sensor for various fields of
experimental physics. It has been argued, however, that variation of APD gain
with temperature could be a serious problem preventing APDs from replacing
traditional photomultiplier tubes (PMTs) in some applications. Here we develop
an active gain-control system to keep the APD gain stable under moderate
temperature variations. As a performance demonstration of the proposed system,
we have tested the response of a scintillation photon detector consisting of a
5x5 mm^2 reverse-type APD optically coupled with a CsI(Tl) crystal. We show
that the APD gain was successfully controlled under a temperature variation of
DT = 20deg, within a time-cycle of 6000 sec. The best FWHM energy resolution of
6.1+-0.2 % was obtained for 662 keV gamma-rays, and the energy threshold was as
low as 6.5 keV, by integrating data from +20deg - 0deg cycles. The
corresponding values for -20deg - 0deg cycles were 6.9+-0.2 % and 5.2 keV,
respectively. These results are comparable, or only slightly worse than that
obtained at a fixed temperature. Our results suggest new potential uses for
APDs in various space researches and nuclear physics. As examples, we briefly
introduce the NeXT and Cute-1.7 satellite missions that will carry the APDs as
scientific instruments for the first time.


title: Roche tomography of cataclysmic variables -- III. Starspots on AE Aqr

abstract:
  We present a Roche tomography reconstruction of the secondary star in the
cataclysmic variable AE Aqr. The tomogram reveals several surface
inhomogeneities that are due to the presence of large, cool starspots. In
addition to a number of lower-latitude spots, the maps also show the presence
of a large high latitude spot similar to that seen in Doppler images of
rapidly-rotating isolated stars, and a relative paucity of spots at a latitude
of 40 degrees. In total, we estimate that some 18 per cent of the Northern
hemisphere of AE Aqr is spotted.
  We have also applied the entropy landscape technique to determine accurate
parameters for the binary system. We obtain optimal masses of M_1 = 0.74 solar
masses, M_2 = 0.50 solar masses, a systemic velocity = -63 km/s and an orbital
inclination of i = 66 degrees.
  Given that this is the first study to successfully image starspots on the
secondary star in a cataclysmic variable, we discuss the role that further
studies of this kind may play in our understanding of these binaries.


title: MACHOs in dark matter haloes

abstract:
  Using eight dark matter haloes extracted from fully-self consistent
cosmological N-body simulations, we perform microlensing experiments. A
hypothetical observer is placed at a distance of 8.5 kpc from the centre of the
halo measuring optical depths, event durations and event rates towards the
direction of the Large Magellanic Cloud. We simulate 1600 microlensing
experiments for each halo. Assuming that the whole halo consists of MACHOs, f =
1.0, and a single MACHO mass is m_M = 1.0 Msun, the simulations yield mean
values of tau = 4.7^{+5.0}_{-2.2} 10^{-7} and Gamma = 1.6^{+1.3}_{-0.6} 10^{-6}
events/star/year. We find that triaxiality and substructure can have major
effects on the measured values so that tau and Gamma values of up to three
times the mean can be found. If we fit our values of tau and Gamma to the MACHO
collaboration observations (Alcock et al. 2000), we find f =
0.23^{+0.15}_{-0.13} and m_M = 0.44^{+0.24}_{-0.16}. Five out of the eight
haloes under investigation produce f and m_M values mainly concentrated within
these bounds.


title:
A test of the power law relationship between gamma-ray burst pulse width
  ratio and energy expected in fireballs or uniform jets

abstract:
  Recently, under the assumption that the Doppler effect of the
relativistically expanding fireball surface is important, Qin et al. showed
that in most cases the power law relationship between the pulse width and
energy of gamma-ray bursts (GRBs)would exist in a certain energy range. We
check this prediction with two GRB samples which contain well identified
pulses. A power law anti-correlation between the full pulse width and energy
and a power law correlation between the pulse width ratio and energy are seen
in the light curves of the majority (around 65%) of bursts of the two samples
within the energy range of BATSE, suggesting that these bursts are likely to
arise from the emission associated with the shocks occurred on a
relativistically expanding fireball surface. For the rest of the bursts, the
relationships between these quantities were not predicted previously. We
propose to consider other spectral evolutionary patterns or other radiation
mechanisms such as a varying synchrotron or Comptonized spectrum to check if
the observed relationships for these rest bursts can also be accounted for by
the Doppler model. In addition, we find that the upper limits of the width
ratio for the two samples do not exceed 0.9, in agrement with what predicted
previously by the Doppler model. The plateau/power law/plateau and the peaked
features predicted and detected previously by Qin et al. are generally
observed, with the exceptions being noticed only in a few cases. According to
the distinct values of two power law indices of FWHM and ratio and energy, we
divide the bursts into three subsets which are located in different areas of
the two indices plane. We suspect that different locations of the two indices
might correspond to different mechanisms.


title: Deuterated molecules in DM Tau: DCO+, but no HDO

abstract:
  We report the detection of the J=2-1 line of DCO+ in the proto-planetary disk
of DM Tau and re-analyze the spectrum covering the 465 GHz transition of HDO in
this source, recently published by Ceccarelli et al. (2005). A modelling of the
DCO+ line profile with the source parameters derived from high resolution HCO+
observations yields a DCO+/HCO+ abundance ratio of about 0.004, an order of
magnitude smaller than that derived in the low mass cores. The re-analysis of
the 465 GHz spectrum, using the proper continuum flux (0.5 Jy) and source
systemic velocity (6.05 km/s), makes it clear that the absorption features
attributed to HDO and C6H are almost certainly unrelated to these species. We
show that the line-to-continuum ratio of an absorption line in front of a
Keplerian disk can hardly exceed the ratio of the turbulent velocity to the
projected rotation velocity at the disk edge, unless the line is optically very
thick (tau > 10 000). This ratio is typically 0.1-0.3 in proto-planetary disks
and is about 0.15 in DM Tau, much smaller than that for the alleged absorption
features. We also show that the detection of H2D+ in DM Tau, previously
reported by these authors, is only a 2-sigma detection when the proper velocity
is adopted. So far, DCO+ is thus the only deuterated molecule clearly detected
in proto-planetary disks.


title: Prompt emission spectra from the photosphere of a GRB

abstract:
  I explore the observational appearance of the photosphere of an
ultrarelativistic flow with internal dissipation of energy (``dissipative'' GRB
models). As a case study, I use the magnetic reconnection model (AC model) that
makes robust predictions on the energy dissipation rates at different radii in
the flow. With analytical and numerical tools for the radiative transfer
problem, I show that the flow develops a hot photosphere where inverse Compton
scattering leads to highly non-thermal spectra. For a wide range of
luminosities and baryon loadings of the flow, this spectrum is very close to
the observed prompt GRB emission. Its luminosity ranges from ~3 to 20% of that
of the total energy input.


title:
Detection of the ISW effect and corresponding dark energy constraints
  made with directional spherical wavelets

abstract:
  Using a directional spherical wavelet analysis we detect the integrated
Sachs-Wolfe (ISW) effect, indicated by a positive correlation between the
first-year Wilkinson Microwave Anisotropy Probe (WMAP) and NRAO VLA Sky Survey
(NVSS) data. Detections are made using both a directional extension of the
spherical Mexican hat wavelet and the spherical butterfly wavelet. We examine
the possibility of foreground contamination and systematics in the WMAP data
and conclude that these factors are not responsible for the signal that we
detect. The wavelet analysis inherently enables us to localise on the sky those
regions that contribute most strongly to the correlation. On removing these
localised regions the correlation that we detect is reduced in significance, as
expected, but it is not eliminated, suggesting that these regions are not the
sole source of correlation between the data. This finding is consistent with
predictions made using the ISW effect, where one would expect weak correlations
over the entire sky. In a flat universe the detection of the ISW effect
provides direct and independent evidence for dark energy. We use our detection
to constrain dark energy parameters by deriving a theoretical prediction for
the directional wavelet covariance statistic for a given cosmological model.
Comparing these predictions with the data we place constraints on the
equation-of-state parameter $w$ and the vacuum energy density $\Omega_\Lambda$.
We also consider the case of a pure cosmological constant, i.e. $w=-1$. For
this case we rule out a zero cosmological constant at greater than the 99.9%
significance level. All parameter estimates that we obtain are consistent with
the standand cosmological concordance model values.


title:
SAURON observations of Sa bulges: the formation of a kinematically
  decoupled core in NGC5953

abstract:
  We present results from our ongoing effort to understand the nature and
evolution of nearby galaxies using the SAURON integral-field spectrograph. In
this proceeding we focus on the study of the particular case formed by the
interacting galaxies NGC5953 and NGC5954. We present stellar and gas kinematics
of the central regions of NGC5953. We use a simple procedure to determine the
age of the stellar populations in the central regions and argue that we may be
witnessing the formation of a kinematically decoupled component from cold gas
being acquired during the ongoing interaction with NGC5954.


title:
Stellar Orbit Constraints on Neutralino Annihilation at the Galactic
  Center

abstract:
  Dark matter annihilation has been proposed to explain the TeV gamma rays
observed from the Galactic Center. We study constraints on this hypothesis
coming from the mass profile around the Galactic Center measured by observing
stellar dynamics. We show that for current particle models, the constraints on
the dark matter density profile from measurements of mass by infrared
observations are comparable to the constraints from the measurements of the TeV
source extension.


title: WMAP First Year Sky Map: Hints of Poincare Dodecahedral Topology

abstract:
  Several analyses of the cosmic microwave background map made by the satellite
WMAP suggest that the global shape of a spatial section of the Universe is that
of a Poincare dodecahedral space. A summary of some of these analyses and a
description of independent tests which should be able to either increase
confidence in the hypothesis or else refute it to extremely high significance
will be presented.