title: GRB 050814 at z = 5.3 and the Redshift Distribution of Swift GRBs

abstract:
  We report optical, near-infrared and X-ray observations of the afterglow of
GRB 050814, which was seen to exhibit very red optical colours. By modelling
its spectral energy distribution we find that z = 5.3 +/- 0.3. We next present
a carefully selected sample of 19 Swift GRBs, intended to estimate in an
unbiased way the GRB redshift distribution, including the mean redshift
(z_mean) as well as constraints on the fraction of high-redshift bursts. We
find that z_mean = 2.7 and that at least 5% of the GRBs originate at z > 5. The
redshift distribution of the sample is qualitatively consistent with models
where the GRB rate is proportional to the star formation rate in the Universe.
The high mean redshift of this GRB sample and the wide redshift range clearly
demonstrates the suitability of GRBs as efficient probes of galaxies and the
intergalactic medium over a significant fraction of the history of the
Universe.


title: Cosmological parameters from Galaxy Clusters: an Introduction

abstract:
  This lecture is an introduction to cosmological tests with clusters of
galaxies. Here I do not intend to provide a complete review of the subject, but
rather to describe the basic procedures to set up the fitting machinery to
constrain cosmological parameters from clusters, and to show how to handle data
with a critical insight. I will focus mainly on the properties of X-ray
clusters of galaxies, showing their success as cosmological tools, to end up
discussing the complex thermodynamics of the diffuse intracluster medium and
its impact on the cosmological tests.


title: Large Scale structure in the HI Parkes ALL-Sky Survey (HIPASS)

abstract:
  We study the clustering properties of the recently compiled HIPASS neutral
hydrogen (HI) sources catalogue using the two point correlation function in
redshift space. If the two point correlation is modelled as a power law,
$\xi(r)=(r_{0}/r)^{\gamma}$, then the best-fitting parameters for the HI
selected galaxies are $r_{0}=4.3 \pm 0.3 h^{-1}$ Mpc with $\gamma=1.42 \pm
0.14$. Fixing the slope to its universal value $\gamma=1.8$, we obtain $r_{0}=
4.1^{+0.2}_{-0.3} h^{-1}$ Mpc. Comparing the measured two point correlation
function with the predictions of the concordance cosmological model, we find
that at the present epoch the HI selected galaxies are anti-biased with respect
to the underline matter fluctuation field with bias value being $b_{0}\simeq
0.63$. Also, we investigate the evolution of the linear bias factor, $b(z)$,
and we find to be a strongly dependent function of redshift. Finally, we
estimate the HI selected galaxies redshift space distortion parameter $\beta
\simeq \Omega_{\rm m}^{0.6}/b_{0}$ in order to correct the correlation function
for the peculiar motions and we find $\beta\simeq 0.77$. Taking into account
the corrections for the redshift space distortions the HI correlation length in
real space is $r^{\rm re}_{0}=3^{+0.4}_{-0.3}h^{-1}$Mpc for $\gamma=1.42$ while
using $\gamma=1.8$ we get $r^{\rm re}_{0}= 3.1 \pm 0.3 h^{-1}$Mpc.


title: Gamma Ray Fresnel lenses - why not?

abstract:
  Fresnel lenses offer the possibility of concentrating the flux of X-rays or
gamma-rays flux falling on a geometric area of many square metres onto a focal
point which need only be a millimetre or so in diameter (and which may even be
very much smaller). They can do so with an efficiency that can approach 100%,
and yet they are easily fabricated and have no special alignment requirements.
Fresnel lenses can offer diffraction-limited angular resolution, even in a
domain where that limit corresponds to less than a micro second of arc.
  Given all these highly desirable attributes, it is natural to ask why Fresnel
gamma ray lenses are not already being used, or at least why there is not yet
any mission that plans to use the technology. Possible reasons (apart from the
obvious one that nobody thought of doing so) include the narrow bandwidth of
simple Fresnel lenses, their very long focal length, and the problems of target
finding. It is argued that none of these is a "show stopper" and that this
technique should be seriously considered for nuclear astrophysics.


title: The lack of close binaries among hot horizontal branch stars in NGC6752

abstract:
  We present the results of a spectroscopic search for close binaries among
horizontal branch (HB) stars in NGC6752. We used the ESO VLT-FORS2 instrument
to obtain medium resolution (R=4100) spectra of 51 hot HB stars with 8000 <
Teff < 32000 K during four consecutive nights. Eighteen of our targets are
extreme horizontal branch (EHB) stars with Teff > 22000 K. Radial velocity
variations were measured with cross-correlation techniques and we carefully
evaluated the statistical and systematic errors associated with them. No close
binary system has been detected among our 51 targets. The data corrected for
instrumental effects indicate that the radial velocity variations are always
below 15 km/s (3sigma level). From a statistical analysis of our results, we
conclude that (at 95 confidence level) the fraction of binaries with a ~0.5
solar masses companion among EHB stars in NGC6752 is smaller than 20%. This
empirical evidence sharply contrasts with what has been found for hot subdwarfs
in the field, and opens new questions about the formation of EHB stars in
globular clusters (and possibly in the field as well.


title: Elements of dodecahedral cosmology

abstract:
  A general method for the determination of the harmonics of quotients of the
3-sphere is given. They can all be deduced from three objects already known
from Klein. We further show explicitly how these harmonics can be organized in
irreducible representations of the holonomy group: this allows for the
determination of the full correlation matrix of the Cosmic Microwave Background
in the spherical harmonics basis.


title: Accurate photometry of extended spherically symmetric sources

abstract:
  We present a new method to derive reliable photometry of extended spherically
symmetric sources from {\it HST} images (WFPC2, ACS/WFC and NICMOS/NIC2
cameras), extending existing studies of point sources and marginally resolved
sources. We develop a new approach to accurately determine intrinsic sizes of
extended spherically symmetric sources, such as star clusters in galaxies
beyond the Local Group (at distances <~ 20 Mpc), and provide a detailed
cookbook to perform aperture photometry on such sources, by determining
size-dependent aperture corrections (ACs) and taking sky oversubtraction as a
function of source size into account. In an extensive Appendix, we provide the
parameters of polynomial relations between the FWHM of various input profiles
and those obtained by fitting a Gaussian profile (which we have used for
reasons of computational robustness, although the exact model profile used is
irrelevant), and between the intrinsic and measured FWHM of the cluster and the
derived AC. Both relations are given for a number of physically relevant
cluster light profiles, intrinsic and observational parameters. AC relations
are provided for a wide range of apertures. Depending on the size of the source
and the annuli used for the photometry, the absolute magnitude of such extended
objects can be underestimated by up to 3 mag, corresponding to an error in mass
of a factor of 15. We carefully compare our results to those from the more
widely used DeltaMag method, and find an improvement of a factor of 3--40 in
both the size determination and the AC.


title: HESS Observations of Pulsar Wind Nebulae

abstract:
  The high resolution capabilities of the High Energy Stereoscopic System
(HESS) introduced a new era in Gamma-Ray Astronomy, and opens a new window on
pulsar wind nebula (PWN) research. A rotationally induced jet (associated with
PSR B1509-58) is resolved for the first time in gamma-rays, allowing us to
trace the particle transport directly, without having the complicating effect
of spatially varying field distributions on the synchrotron emissivity. For PWN
older or more extended than Crab (i.e. those with lower field strengths), HESS
also reveals the properties of electrons contributing to the EUV/soft X-ray
synchrotron bands, whereas EUV/soft X-rays suffer from severe interstellar
absorption effects. Finally, HESS morphological studies of evovled PWN also
allow us to directly measure the effects of assymetric reverse shock
interactions due to SNR forward shock expansion into the inhomogeneous
interstellar medium.


title:
The origin of GEMS in IDPs as deduced from microstructural evolution of
  amorphous silicates with annealing

abstract:
  We present laboratory studies of the micro-structural evolution of an
amorphous ferro-magnesian silicate, of olivine composition, following thermal
annealing under vacuum. Annealing under vacuum was performed at temperatures
ranging from 870 to 1020 K. After annealing spheroidal metallic nano-particles
(2-50 nm) are found within the silicate films. We interpret this microstructure
in terms of a reduction of the initial amorphous silicate FeO component,
because of the carbon-rich partial pressure in the furnace due to pumping
mechanism. Annealing in a controlled oxygen-rich atmosphere confirms this
interpretation. The observed microstructures closely resemble those of the GEMS
(Glass with Embedded Metal and Sulphides) found in chondritic IDPs
(Interplanetary Dust Particles). Since IDPs contain abundant carbonaceous
matter, a solid-state reduction reaction may have occurred during heating in
the hot inner regions of the proto-solar disc. Related to this, the presence of
forsterite grains grown from the amorphous precursor material clearly
demonstrates that condensation from gaseous species is not required to explain
the occurrence of forsterite around young protostars and in comets. Forsterite
grains in these environments can be formed directly in the solid phase by
thermal annealing of amorphous ferro-magnesian silicates under reducing
conditions.


title:
Abell 2111: An Optical and Radio Study of the Richest Butcher-Oemler
  Cluster

abstract:
  We present an in-depth analysis of the Butcher-Oemler cluster A2111,
including new optical spectroscopy plus a deep Very Large Array (VLA) radio
continuum observation. These are combined with optical imaging from the Sloan
Digital Sky Survey (SDSS) to assess the activity and properties of member
galaxies. Prior X-ray studies have suggested A2111 is a head-on cluster merger,
a dynamical state which might be connected to the high level of activity
inferred from its blue fraction. We are able to directly assess this claim,
using our spectroscopic data to identify 95 cluster members among 196 total
galaxy spectra. These galaxy velocities do not themselves provide significant
evidence for the merger interpretation, however they are consistent with it
provided the system is viewed near the time of core passage and at a viewing
angle >~30 degrees different from the merger axis. The SDSS data allow us to
confirm the high blue fraction for A2111, f_b = 0.15 +/- 0.03 based on
photometry alone and f_b = 0.23 +/- 0.03 using spectroscopic data to remove
background galaxies. We are able to detect 175 optical sources from the SDSS in
our VLA radio data, of which 35 have redshift information. We use the SDSS
photometry to determine photometric redshifts for the remaining 140
radio-optical sources. In total we identify up to 26 cluster radio galaxies, 14
of which have spectroscopic redshifts. The optical spectroscopy and radio data
reveal a substantial population of dusty starbursts within the cluster. The
high blue fraction and prevalence of star formation is consistent with the
hypothesis that dynamically-active clusters are associated with more active
member galaxies than relaxed clusters.


title: On the origin of the Fe K-alpha line cores in Active Galactic Nuclei

abstract:
  X-ray observations with Chandra and XMM-Newton have shown that there are
relatively narrow cores to the iron K-alpha emission lines in active galactic
nuclei (AGN). Plausible origins for this core emission include the outer
regions of an accretion disk, a pc-scale molecular torus, and the optical
broad-line region (BLR). Using data from the literature it is shown that no
correlation exists between the Fe K-alpha core width and the BLR (specifically
H-beta) line width. This shows that in general the iron K-alpha core emission
does not arise from the BLR. There is a similar lack of correlation between the
width of the Fe K-alpha core and black hole mass. The average K-alpha width is
about a factor of two lower than the H-beta width. It therefore seems likely
that in many cases the narrow core arises in the torus. There is a very wide
range of observed Fe K-alpha core widths, however, and this argues for multiple
origins. The simplest explanation for the observed line profiles in AGN is that
they are due to a mixing of very narrow emission from the inner edge of the
torus, and broadened emission from the accretion disk, in varying proportions
from object-to-object.


title:
Charon's radius and density from the combined data sets of the 2005 July
  11 occultation

abstract:
  The 2005 July 11 C313.2 stellar occultation by Charon was observed by three
separate research groups, including our own, at observatories throughout South
America. Here, the published timings from the three data sets have been
combined to more accurately determine the mean radius of Charon: 606.0 +/- 1.5
km. Our analysis indicates that a slight oblateness in the body (0.006 +/-
0.003) best matches the data, with a confidence level of 86%. The oblateness
has a pole position angle of 71.4 deg +/- 10.4 deg and is consistent with
Charon's pole position angle of 67 deg. Charon's mean radius corresponds to a
bulk density of 1.63 +/- 0.07 g/cm3, which is significantly less than Pluto's
(1.92 +/- 0.12 g/cm3). This density differential favors an impact formation
scenario for the system in which at least one of the impactors was
differentiated. Finally, unexplained differences between chord timings measured
at Cerro Pachon and the rest of the data set could be indicative of a
depression as deep as 7 km on Charon's limb.


title: Transition from Galactic to Extra-Galactic Cosmic Rays

abstract:
  In this paper we review the main features of the observed Cosmic Rays
spectrum in the energy range $10^{17} {\rm eV}~\div~10^{20} {\rm eV}$. We
present a theoretical model that explains the main observed features of the
spectrum, namely the second Knee and Dip, and implies a transition from
Galactic to Extra-Galactic cosmic rays at energy $E\simeq 10^{18}$ eV, with a
proton dominated Extra-Galactic spectrum.


title:
Surface temperature and synthetic spectral energy distributions for
  rotationally deformed stars

abstract:
  The spectral energy distribution (SED) of a non-spherical star could differ
significantly from the SED of a spherical star with the same average
temperature and luminosity. Calculation of the SED of a deformed star is often
approximated as a composite of several spectra, each produced by a plane
parallel model of given effective temperature and gravity. The weighting of
these spectra over the stellar surface, and hence the inferred effective
temperature and luminosity, will be dependent on the inclination of the
rotation axis of the star with respect to the observer, as well as the
temperature and gravity distribution on the stellar surface. Here we calculate
the surface conditions of rapidly rotating stars with a 2D stellar structure
and evolution code and compare the effective temperature distribution to that
predicted by von Zeipel's law. We calculate the composite spectrum for a
deformed star by interpolating within a grid of intensity spectra of plane
parallel model atmospheres and integrating over the surface of the star. Using
this method, we find that the deduced variation of effective temperature with
inclination can be as much as 3000 K for an early B star, depending on the
details of the underlying model.


title:
Low Redshift Intergalactic Absorption Lines in the Spectrum of
  HE0226-4110

abstract:
  We present an analysis of the FUSE and STIS E140M spectra of HE0226-4110
(z=0.495). We detect 56 Lyman absorbers and 5 O VI absorbers. The number of
intervening O VI systems per unit redshift with W>50 m\AA is dN(O VI)/dz~ 11.
The O VI systems unambiguously trace hot gas only in one case. For the 4 other
O VI systems, photoionization and collisional ionization models are viable
options to explain the observed column densities of the O VI and the other
ions. If the O VI systems are mostly photoionized, only a fraction of the
observed O VI will contribute to the baryonic density of the warm-hot ionized
medium (WHIM) along this line of sight. Combining our results with previous
ones, we show that there is a general increase of N(O VI) with increasing b(O
VI). Cooling flow models can reproduce the N-b distribution but fail to
reproduce the observed ionic ratios. A comparison of the number of O I, O II, O
III, O IV, and O VI systems per unit redshift show that the low-z IGM is more
highly ionized than weakly ionized. We confirm that photoionized O VI systems
show a decreasing ionization parameter with increasing H I column density. O VI
absorbers with collisional ionization/photoionization degeneracy follow this
relation, possibly suggesting that they are principally photoionized. We find
that the photoionized O VI systems in the low redshift IGM have a median
abundance of 0.3 solar. We do not find additional Ne VIII systems other than
the one found by Savage et al., although our sensitivity should have allowed
the detection of Ne VIII in O VI systems at T~(0.6-1.3)x10^6 K (if CIE
applies). Since the bulk of the WHIM is believed to be at temperatures T>10^6
K, the hot part of the WHIM remains to be discovered with FUV--EUV metal-line
transitions.


title:
The IAU Resolutions on Astronomical Reference Systems, Time Scales, and
  Earth Rotation Models

abstract:
  Recent resolutions passed by the International Astronomical Union (IAU) on
astronomical reference systems, time scales, and Earth rotation models are the
most significant set of international agreements in positional astronomy in
several decades. These resolutions, the result of over ten years of
international research and study, provide a coherent set of foundational
standards for the treatment of astrometric data and the modeling of dynamics in
the solar system. This circular explains these resolutions and provides a
complete set of practical formulas for their implementation. The six main
chapters cover relativity, time scales, the fundamental celestial reference
system, ephemerides of solar system bodies, precession and nutation, and
modeling the Earth's rotation.


title:
Constraining Disk Parameters of Be Stars using Narrowband H-alpha
  Interferometry with the NPOI

abstract:
  Interferometric observations of two well-known Be stars, gamma Cas and phi
Per, were collected and analyzed to determine the spatial characteristics of
their circumstellar regions. The observations were obtained using the Navy
Prototype Optical Interferometer equipped with custom-made narrowband filters.
The filters isolate the H-alpha emission line from the nearby continuum
radiation, which results in an increased contrast between the interferometric
signature due to the H-alpha-emitting circumstellar region and the central
star. Because the narrowband filters do not significantly attenuate the
continuum radiation at wavelengths 50 nm or more away from the line, the
interferometric signal in the H-alpha channel is calibrated with respect to the
continuum channels. The observations used in this study represent the highest
spatial resolution measurements of the H-alpha-emitting regions of Be stars
obtained to date. These observations allow us to demonstrate for the first time
that the intensity distribution in the circumstellar region of a Be star cannot
be represented by uniform disk or ring-like structures, whereas a Gaussian
intensity distribution appears to be fully consistent with our observations.


title:
The Evolution of Galaxy Mergers and Morphology at z<1.2 in the Extended
  Groth Strip

abstract:
  We present the quantitative rest-frame B morphological evolution and galaxy
merger fractions at 0.2 < z < 1.2 as observed by the All-wavelength Extended
Groth Strip International Survey (AEGIS). We use the Gini coefficent and M_20
to identify major mergers and classify galaxy morphology for a volume-limited
sample of 3009 galaxies brighter than 0.4 L_B^*, assuming pure luminosity
evolution of 1.3 M_B per unit redshift. We find that the merger fraction
remains roughly constant at 10 +/- 2% for 0.2 < z < 1.2. The fraction of
E/S0/Sa increases from 21+/- 3% at z ~ 1.1 to 44 +/- 9% at z ~ 0.3, while the
fraction of Sb-Ir decreases from 64 +/- 6% at z ~ 1.1 to 47 +/- 9% at z ~ 0.3.
The majority of z < 1.2 Spitzer MIPS 24 micron sources with L(IR) > 10^11 L_sun
are disk galaxies, and only ~ 15% are classified as major merger candidates.
Edge-on and dusty disk galaxies (Sb-Ir) are almost a third of the red sequence
at z ~ 1.1, while E/S0/Sa makeup over 90% of the red sequence at z ~ 0.3.
Approximately 2% of our full sample are red mergers. We conclude (1) the galaxy
merger rate does not evolve strongly between 0.2 < z < 1.2; (2) the decrease in
the volume-averaged star-formation rate density since z ~ 1 is a result of
declining star-formation in disk galaxies rather than a disappearing population
of major mergers; (3) the build-up of the red sequence at z < 1 can be
explained by a doubling in the number of spheroidal galaxies since z ~ 1.2.


title:
The Large and Small Scale Structures of Dust in the Star-Forming Perseus
  Molecular Cloud

abstract:
  We present an analysis of ~3.5 square degrees of submillimetre continuum and
extinction data of the Perseus molecular cloud. We identify 58 clumps in the
submillimetre map and we identify 39 structures (`cores') and 11 associations
of structures (`super cores') in the extinction map. The cumulative mass
distributions of the submillimetre clumps and extinction cores have steep
slopes (alpha ~ 2 and 1.5 - 2 respectively), steeper than the Salpeter IMF
(alpha = 1.35), while the distribution of extinction super cores has a shallow
slope (alpha ~ 1). Most of the submillimetre clumps are well fit by stable
Bonnor-Ebert spheres with 10K < T < 19K and 5.5 < log_10(P_ext/k) < 6.0. The
clumps are found only in the highest column density regions (A_V > 5 - 7 mag),
although Bonnor-Ebert models suggest that we should have been able to detect
them at lower column densities if they exist. These observations provide a
stronger case for an extinction threshold than that found in analysis of less
sensitive observations of the Ophiuchus molecular cloud. The relationship
between submillimetre clumps and their parent extinction core has been
analyzed. The submillimetre clumps tend to lie offset from the larger
extinction peaks, suggesting the clumps formed via an external triggering
event, consistent with previous observations.


title: Evolutive Unification in Composite Active Galactic Nuclei

abstract:
  In this paper we explore an evolutionary Unified scenario involving super
massive black hole and starburst with outflow, that seems capable of explaining
most of the observational properties of at least part of AGNs. Our suggestion
is explored inside the expectations of the Starburst model close associated
with the AGN where the NLR, BLR and BAL region are produced in part by the
outflow process with shells and in compact supernova remnants. The outflow
process in BAL QSOs with extreme IR and Fe II emission is studied. In addition,
the Fe II poblem regarding the BLR of AGN is analysed. Neither the correlations
between the BAL, IR emission, FeII intensity and the intrinsic properties of
the AGN are clearly understood. We suggest here that the behaviour of the BAL,
IR and FeII emission in AGNs can be understood inside an evolutionary and
composite model for AGNs. In our model, strong BAL systems and Fe II emission
are present (and intense) in young IR objects. Orientation/ obscuration effects
take the role of a second parameter providing the segregation between Sy1/Sy2
and BLRG/NLRG.


title:
Comprehensive Analysis of RXTE Data from Cyg X-1: Spectral
  Index-Quasi-Periodic Oscillation Frequency-Luminosity Correlations

abstract:
  We present timing and spectral analysis of ~ 2.2 Ms of RXTE archival data
from Cyg X-1. Using a generic Comptonization model we reveal that the spectrum
of Cyg X-1 consists of three components: a thermal seed photon spectrum, a
Comptonized part of the seed photon spectrum and the iron line. We find a
strong correlation between the 0.1-20 Hz frequencies of quasiperiodic
oscillations (QPOs) and the spectral index. Presence of two spectral phases
(states) are clearly seen in the data when the spectral indices saturate at low
and high values of QPO frequencies. This saturation effect was discovered
earlier in a number of black hole candidate (BHC) sources and now we strongly
confirm this phenomenon in Cyg X-1. In the soft state this index-QPO frequency
correlation shows a saturation of the photon index Gamma ~ 2.1 at high values
of the low frequency \nu_{L}. The saturation level of Gamma~ 2.1 is the lowest
value found yet in BHCs. The bolometric luminosity does not show clear
correlation with the index. We also show that Fe K_{\alpha} emission line
strength (equivalent width, EW) correlates with the QPO frequency. The EW
increases from 200 eV in the low/hard state to 1.5 keV in the high/soft state.
The observational correlations revealed compel us to propose a scenario for the
spectral transition and iron line formation which occur in BHC sources. We also
present the spectral state (power-law index) evolution for eight years of Cyg
X-1 observations by RXTE.


title: Do extragalactic cosmic rays induce cycles in fossil diversity?

abstract:
  Recent work has revealed a 62 (+/-) 3-million-year cycle in the fossil
diversity in the past 542 My, however no plausible mechanism has been found. We
propose that the cycle may be caused by modulation of cosmic ray (CR) flux by
the Solar system vertical oscillation (64 My period) in the galaxy, the
galactic north-south anisotropy of CR production in the galactic
halo/wind/termination shock (due to the galactic motion toward the Virgo
cluster), and the shielding by galactic magnetic fields. We revisit the
mechanism of CR propagation and show that CR flux can vary by a factor of about
4.6 and reach a maximum at north-most displacement of the Sun. The very high
statistical significance of (i) the phase agreement between Solar north-ward
excursions and the diversity minima and (ii) the correlation of the magnitude
of diversity drops with CR amplitudes through all cycles provide solid support
for our model. Various observational predictions which can be used to confirm
or falsify our hypothesis are presented.

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


title:
Comptonisation of Cosmic Microwave Background Photons in Dwarf
  Spheroidal Galaxies

abstract:
  We present theoretical modelling of the electron distribution produced by
annihilating neutralino dark matter in dwarf spheroidal galaxies (dSphs). In
particular, we follow up the idea of Colafrancesco (2004) and find that such
electrons distort the cosmic microwave background (CMB) by the
Sunyaev-Zeldovich effect. For an assumed neutralino mass of 10 GeV and beam
size of 1'', the SZ temperature decrement is of the order of nano-Kelvin for
dSph models with a soft core. By contrast, it is of the order of micro-Kelvin
for the strongly cusped dSph models favoured by some cosmological simulations.
Although this is out of reach of current instruments, it may well be detectable
by future mm telescopes, such as ALMA. We also show that the upscattered CMB
photons have energies within reach of upcoming X-ray observatories, but that
the flux of such photons is too small to be detectable soon. Nonetheless, we
conclude that searching for the dark matter induced Sunyaev-Zeldovich effect is
a promising way of constraining the dark distribution in dSphs, especially if
the particles are light.


title:
FUV and X-ray Observations of the Reverse Shock in the SMC SNR 1E
  0102.2-7219

abstract:
  We present FUSE and XMM-Newton data for the reverse shock of the O-rich SNR
1E0102.2-7219 in the SMC. The FUSE observations cover three regions with
significantly different optical [O III] intensities, all associated with the
relatively bright part of the X-ray ring. Emission lines of O VI 1032, 1038 are
clearly detected in the FUSE spectra. By combining this O VI doublet emission
with the O VII triplet and O VIII Lyalpha fluxes from the XMM-Newton spectra
and assuming a non-equilibrium ionization model with a single ionization
timescale for the spectra, we are able to find a narrow range of temperatures
and ionization timescales that are consistent with the respective line ratios.
However, if we assume a plane-parallel shock model with a distribution of
ionization timescales, the O VI emission appears to be inconsistent with O VII
and O VIII in X-rays. We also analyze the total XMM-Newton EPIC-MOS 1/2 spectra
for the three regions. The X-ray spectra are dominated by strong emission lines
of O, Ne, and Mg, however, we detect an emission component that accounts for 14
- 25% of the flux and can be attributed to shocked ISM. We find that there is
no consistent set of values for the temperature and ionization timescale which
can explain the observed line ratios for O, Ne, and Mg. This would be
consistent with a structured distribution of the ejecta as the O, Ne, Mg would
have interacted with the reverse shock at different times.


title: Strange stars at finite temperature

abstract:
  We calculate strange star properties, using large N_c approximation with
built-in chiral symmetry restoration (CSM). We used a relativistic Hartree Fock
mean field approximation method, using a modified Richardson potential with two
scale parameters \Lambda and \Lambda^\prime, to find a new set of equation of
states for strange quark matter. We take the effect of temperature (T) on gluon
mass, in addition to the usual density dependence, and find that the transition
T from hadronic matter to strange matter is 80 MeV. Therefore formation of
strange stars may be the only signal for formation of QGP with asymptotic
freedom and CSM.


title: The Sky in Dust -- Methods and Prospects of Dust Astronomy

abstract:
  Information about the make-up of the galaxy arrives in the Solar system in
many forms: photons of different energies, classically collected by ground- and
space-based telescopes, neutral and charged atomic particles, and solid
macroscopic particles: cosmic dust particles. Dust particles, like photons,
carry information from remote sites in space and time. This information can be
analysed in order to understand the processes and mechanisms that are involved
in the formation and evolution of solid matter in the galaxy. This approach is
called ``Dust Astronomy'' which is carried out by means of a dust telescope on
a dust observatory in space. The analysis of cosmic grains collected in the
high atmosphere of the Earth has shown that each dust grain is a small world
with various sub-grains featuring different galactic origin and evolution,
which is identified on the basis of elementary and isotopic analysis.
Independent information about the origin and evolution of the grains coming
from the kinematic properties of the arrival trajectory would be invaluable for
linking the isotopic signature of the formation of heavy elements in old stars
and supernovae to distinctive regions in our galaxy, e.g. known star-forming
regions. Here we present a skymap of potential dust sources together with a
report on already existing lab hardware of a trajectory sensor and a large-area
mass spectrometre.


title: A restoration in the time-symmetric theory and associated new results

abstract:
  The concept of absorption of a photon moving backwards in time is reexamined,
and it is found that its interpretation as absorption is wrong, its original
interpretation rather as an emission being restored. The result is that the
anticosmos is invisible rather than indistinguishable from the cosmos, and as
such it is qualitatevely a candidate for constituting the dark matter.
Newton´s law of gravitation is then generalized to refer either to matter
(of the cosmos) and/or antimatter (of the anticosmos), and quantitatevely is
found for the anticosmos to constitute the dark matter, as being (absolutely)
equal in ammount of antimatter to the ammount of matter in the cosmos.Finally,
a mechanism of gravitational repulsion from antimatter is proposed to explain
the observed deceleration of Pioneer 10 and Pioneer 11, and an analytical way
is exposed to calculate the position, as well as its (anti-)mass, of the
responsible anti-body.


title:
The Chandrasekhar condition of the equilibrium and stability for a star
  in the nonextensive kinetic theory

abstract:
  The idea of Chandrasekhar condition of the equilibrium and stability for a
star is revisited in the nonextensive kinetic theory based on Tsallis entropy.
A new analytical formula generalizing the Chandrasekhar condition is derived by
assuming that the stellar matter is kinetically described by the generalized
Maxwell-Boltzmann distribution in Tsallis statistics. It is found that the
maximum radiation pressure allowed at the center of a star of a given mass is
dependent on the nonextensive parameter q. The Chandrasekhar condition in the
Maxwellian sense is recovered from the new condition in the case of q=1.


title:
Angular Trispectrum of CMB Temperature Anisotropy from Primordial
  Non-Gaussianity with the Full Radiation Transfer Function

abstract:
  We calculate the cosmic microwave background (CMB) angular trispectrum,
spherical harmonic transform of the four-point correlation function, from
primordial non-Gaussianity in primordial curvature perturbations characterized
by a constant non-linear coupling parameter, $f_{\rm NL}$. We fully take into
account the effect of the radiation transfer function, and thus provide the
most accurate estimate of the signal-to-noise ratio of the angular trispectrum
of CMB temperature anisotropy. We find that the predicted signal-to-noise ratio
of the trispectrum summed up to a given $l$ is approximately a power-law,
$(S/N)(<l)\sim 2.2\times 10^{-9}f^2_{\rm NL}l^2$, up to the maximum multipole
that we have reached in our numerical calculation, $l=1200$, assuming that the
error is dominated by cosmic variance. Our results indicate that the
signal-to-noise ratio of the temperature trispectrum exceeds that of the
bispectrum at the critical multipole, $l_c \sim 1500~(50/|f_{\rm NL}|)$.
Therefore, the trispectrum of the Planck data is more sensitive to primordial
non-Gaussianity than the bispectrum for $|f_{\rm NL}|\gtrsim 50$. We also
report the predicted constraints on the amplitude of trispectrum, which may be
useful for other non-Gaussian models such as curvaton models.


title: Spurs and feathering in spiral galaxies

abstract:
  We present Smoothed Particle Hydrodynamics (SPH) simulations of the response
of gas discs to a spiral potential. These simulations show that the commonly
observed spurs and feathering in spiral galaxies can be understood as being due
to structures present in the spiral arms that are sheared by the divergent
orbits in a spiral potential. Thus, dense molecular cloud-like structures
generate the perpendicular spurs as they leave the spiral arms. Subsequent
feathering occurs as spurs are further sheared into weaker parallel structures
as they approach the next spiral passage. Self-gravity of the gas is not
included in these simulations, stressing that these features are purely due to
the hydrodynamics in spiral shocks. Instead, a necessary condition for this
mechanism to work is that the gas need be relatively cold (1000 K or less) in
order that the shock is sufficient to generate structure in the spiral arms,
and such structure is not subsequently smoothed by the gas pressure.


title: The Cosmic Stellar Birth and Death Rates

abstract:
  The cosmic stellar birth rate can be measured by standard astronomical
techniques. It can also be probed via the cosmic stellar death rate, though
until recently, this was much less precise. However, recent results based on
measured supernova rates, and importantly, also on the attendant diffuse fluxes
of neutrinos and gamma rays, have become competitive, and a concordant history
of stellar birth and death is emerging. The neutrino flux from all past
core-collapse supernovae, while faint, is realistically within reach of
detection in Super-Kamiokande, and a useful limit has already been set. I will
discuss predictions for this flux, the prospects for neutrino detection, the
implications for understanding core-collapse supernovae, and a new limit on the
contribution of type-Ia supernovae to the diffuse gamma-ray background.


title: Hubble's law and Superluminity Recession Velocities

abstract:
  The extension of the so-called "empty" (with gravity and antigravity that
compensate each other in full or do not exist at all) universe and cosmological
redshift in it are considered in this paper. Its flat space-time can be
submitted not only as manifold with Friedman-Robertson-Walker metrics (FRW) of
the general theory of relativity (GR) but also as space-time with usual
Minkowski metrics (M-metrics) of the special theory of relativity (SR); the
transfer of metrics can be done by suitable transformation of reference frame.
Both below-mentioned statements are equally fair for such the universe. First:
the distant galaxies can have superluminity recession velocities in FRW-space
of GR; we have no right to use here the formula of relativistic Doppler effect.
Secondly: the SR theory is fair in the M-space and, accordingly, recession
velocities of the same galaxies here can aspire to the speed of light only.
  In this article it is shown that, despite opposite pictures in FRW-and M-
spaces, in the careful account of all details both approaches yield results
agreed among them. Thus, actually there are no contradictions between the
interpretations of cosmological redshift, based on SR and GR.


title: The formation of molecular clouds in spiral galaxies

abstract:
  We present Smoothed Particle Hydrodynamics (SPH) simulations of molecular
cloud formation in spiral galaxies. These simulations model the response of a
non-self-gravitating gaseous disk to a galactic potential. The spiral shock
induces high densities in the gas, and considerable structure in the spiral
arms, which we identify as molecular clouds. We regard the formation of these
structures as due to the dynamics of clumpy shocks, which perturb the flow of
gas through the spiral arms. In addition, the spiral shocks induce a large
velocity dispersion in the spiral arms, comparable with the magnitude of the
velocity dispersion observed in molecular clouds. We estimate the formation of
molecular hydrogen, by post-processing our results and assuming the gas is
isothermal. Provided the gas is cold ($T\le100$ K), the gas is compressed
sufficiently in the spiral shock for molecular hydrogen formation to occur in
the dense spiral arm clumps. These molecular clouds are largely confined to the
spiral arms, since most molecular gas is photodissociated to atomic hydrogen
upon leaving the arms.


title: Nuclear Astrophysics of Worlds in the String Landscape

abstract:
  Motivated by landscape models in string theory, cosmic nuclear evolution is
analyzed allowing the Standard Model Higgs expectation value w to take values
different from that in our world (w=1), while holding the Yukawa couplings
fixed. Thresholds are estimated, and astrophysical consequences are described,
for several sensitive dependences of nuclear behavior on w. The dependence of
the neutron-proton mass difference on w is estimated based on recent
calculations of strong isospin symmetry breaking, and is used to derive the
threshold of neutron-stable worlds, w ~ 0.6+/- 0.2. The effect of a stable
neutron on nuclear evolution in the Big Bang and stars is shown to lead to
radical differences from our world, such as a predominance of heavy r-process
and s-process nuclei and a lack of normal galaxies, stars and planets. Rough
estimates are reviewed of w thresholds for deuteron stability and the pp and
pep reactions dominant in many stars. A simple model of nuclear resonances is
used to estimate the w dependence of overall carbon and oxygen production
during normal stellar nucleosynthesis; carbon production is estimated to change
by a fraction ~15(1-w). Radical changes in astrophysical behavior seem to
require changes in w of more than a few percent, even for the most sensitive
phenomena.


title:
First Results from the CHARA Array. IV. The Interferometric Radii of
  Low-Mass Stars

abstract:
  We have measured the angular diameters of six M dwarfs with the CHARA Array,
a long-baseline optical interferometer located at Mount Wilson Observatory.
Spectral types range from M1.0 V to M3.0 V and linear radii from 0.38 to 0.69
Rsun. These results are consistent with the seven other M-dwarf radii
measurements from optical interferometry and with those for sixteen stars in
eclipsing binary systems. We compare all directly measured M dwarf radii to
model predictions and find that current models underestimate the true stellar
radii by up to 15-20%. The differences are small among the metal-poor stars but
become significantly larger with increasing metallicity. This suggests that
theoretical models for low mass stars may be missing some opacity source that
alters the computed stellar radii.


title: The Large Peculiar Velocity of the cD Galaxy in Abell 3653

abstract:
  We present a catalogue of galaxies in Abell 3653 from observations made with
the 2dF spectrograph at the Anglo-Australian Telescope. Of the 391 objects
observed, we find 111 are bone-fide members of Abell 3653. We show that the
cluster has a velocity of cz = 32214 +/- 83 km/s (z=0.10738 +/- 0.00027), with
a velocity dispersion typical of rich, massive clusters of sigma_{cz} =
880^{+66}_{-54}. We find that the cD galaxy has a peculiar velocity of 683 +/-
96 km/s in the cluster restframe - some 7sigma away from the mean cluster
velocity, making it one of the largest and most significant peculiar velocities
found for a cD galaxy to date. We investigate the cluster for signs of
substructure, but do not find any significant groupings on any length scale. We
consider the implications of our findings on cD formation theories.


title: Neutron-capture elements in the very metal-poor star HD122563

abstract:
  We obtained high resolution, high S/N spectroscopy for the very metal-poor
star HD122563 with the Subaru Telescope High Dispersion Spectrograph. Previous
studies have shown that this object has excesses of light neutron-capture
elements, while its abundances of heavy ones are very low. In our spectrum
covering 3070 - 4780 A of this object, 19 neutron-capture elements have been
detected, including seven for the first time in this star (Nb, Mo, Ru, Pd, Ag,
Pr, and Sm). Upper limits are given for five other elements including Th. The
abundance pattern shows a gradually decreasing trend, as a function of atomic
number, from Sr to Yb, which is quite different from those in stars with
excesses of r-process elements. This abundance pattern of neutron-capture
elements provides new strong constraints on the models of nucleosynthesis
responsible for the very metal-poor stars with excesses of light
neutron-capture elements but without enhancement of heavy ones.


title: Study of a detector array for Upward Tau Air-Showers

abstract:
  The cosmic ray spectrum extends to energies above 10^20 eV. In direct
production or acceleration models, as well as by photo-pion interaction high
energy cosmic ray flux must contain neutrinos and photons. The latter are
absorbed by cosmic radiations while neutrinos are not. The need of a Neutrino
Astronomy is compelling. In this paper a study of a detector array designed to
measure horizontal tau air-showers emerging from the ground, produced by nu_tau
interactions with the Earth's crust, is presented. Each array unit is composed
of a pair of scintillator tiles mounted on a frame with a front field of view
of about 0.1 sr, optimized to distinguish between up-going and down-going
crossing particles by their time of flight. The detector array sensitivity, the
size of the array and the tau shower identification are discussed. Because of
the almost complete mixing of nu_mu to nu_tau the ultrahigh energy neutrino tau
and its minimal consequent tau-airshower rate is estimated; assuming that the
neutrino energy spectrum follows a Fermi-like power law E^-2, the sensitivity
with 3 years of observation is estimated to be about 60 eV cm^-2s^-1sr^-1 in
the energy range 10^{17-20} eV. This value would provide competitive upper
limit with present and future experiments. We found also that, in the same
time, this system can observe about one GZK neutrino event per km^2.


title:
Systematic errors in the determination of Hubble constant due to the
  asphericity and non-isothermality of clusters of galaxies

abstract:
  Joint analyses on X-ray and Sunyaev-Zel'dovich (SZ) effect of a cluster of
galaxies can give rise to an estimate on the angular diameter distance to the
cluster. With the redshift information of the cluster, the Hubble constant
$H_0$ can then be derived. Furthermore, such measurements on a sample of
clusters with a range of redshift can potentially be used to discriminate
different cosmological models. In this paper, we present statistical studies on
the systematic errors in the determination of $H_0$ due to the triaxiality and
non-isothermality of clusters of galaxies. Different from many other studies
that assume artificially a specific distribution for the intracluster gas, we
start from the triaxial model of dark matter halos obtained from numerical
simulations. The distribution of the intracluster gas is then derived under the
assumption of the hydrodynamic equilibrium. For the equation of state of the
intracluster gas, both the isothermal and the polytropic cases are
investigated. We run Monte Carlo simulations to generate samples of clusters
according to the distributions of their masses, axial ratios, concentration
parameters, as well as line-of-sight directions. To mimic observations, the
estimation of the Hubble constant is done by fitting X-ray and SZ profiles of a
triaxial cluster with the isothermal and spherical $\beta$-model. We find that
for a sample of clusters with $M=10^{14}h^{-1}\hbox{M}_{\odot}$ and $z=0.1$,
the value of the estimated $H_0$ is positively biased with
$H_0^{peak}(estimated)\approx 1.05H_0(true)$ and $H_0^{ave}(estimated)\approx
1.05H_0(true)$ for the isothermal case. For the polytropic case with
$\gamma=1.15$, the bias is rather large with $H_0^{peak}(estimated)\approx
1.35H_0(true)$ and $H_0^{ave}(estimated)\approx 3H_0(true)$. (abridged)


title:
Star Cluster Analyses from Multi-Band Photometry: the Key Advantage of
  SALT's U-band Sensitivity

abstract:
  Conventionally, CMD analyses of nearby star clusters are based on
observations in 2 passbands. They are plagued by considerable degeneracies
between age, metallicity, distance (and extinction) that can largely be
resolved by including additional passbands with U being most appropriate for
young SCs and I or a NIR band for old globular clusters. For star clusters that
cannot be resolved, integrated photometry in suitably selected passbands was
shown to be as accurate as spectroscopy in independently revealing ages,
metallicities, internal extinction, and photometric masses and their respective
1 sigma uncertainties, when analysed with a dedicated analysis tool for their
Spectral Energy Distributions (SEDs) (cf. Anders et al. 2004a, b, de Grijs et
al. 2003b). For external galaxies, rich star cluster populations can thus be
efficiently analysed using deep exposures in 4 suitable filters. Again, the
inclusion of the U-band significantly reduces the uncertainties in the cluster
parameters. The age and metallicity distributions of star cluster systems yield
valuable information about the formation history of their parent galaxies
(Fritze - v. A. 2004). Here, we present our GALEV evolutionary synthesis models
for star clusters of various metallicities (Anders, Fritze - v. A. 2003),
recently extended to include the time evolution of CMDs, the dedicated SED
Analysis Tool AnalySED we developed, show results on the basis of HST data, and
present first data for a young star cluster system in the ongoing spiral-spiral
merger NGC 1487 obtained with SALT during the SALTICAM Performance Verification
Phase.


title:
Magnetoconvection and dynamo coefficients III: alpha-effect and magnetic
  pumping in the rapid rotation regime

abstract:
  Aims. The alpha- and gamma-effects, which are responsible for the generation
and turbulent pumping of large scale magnetic fields, respectively, due to
passive advection by convection are determined in the rapid rotation regime
corresponding to the deep layers of the solar convection zone.
  Methods. A 3D rectangular local model is used for solving the full set of MHD
equations in order to compute the electromotive force (emf), E = <u x b>,
generated by the interaction of imposed weak gradient-free magnetic fields and
turbulent convection with varying rotational influence and latitude. By
expanding the emf in terms of the mean magnetic field, E_i = a_ij <B_j>, all
nine components of a_ij are computed. The diagonal elements of a_ij describe
the alpha-effect, whereas the off-diagonals represent magnetic pumping. The
latter is essentially the advection of magnetic fields by means other than the
underlying large-scale velocity field. Comparisons are made to analytical
expressions of the coefficients derived under the first-order smoothing
approximation (FOSA).
  Results. In the rapid rotation regime the latitudinal dependence of the
alpha-components responsible for the generation of the azimuthal and radial
fields does not exhibit a peak at the poles, as is the case for slow rotation,
but at a latitude of about 30 degrees. The magnetic pumping is predominantly
radially down- and latitudinally equatorward as in earlier studies. The
numerical results compare surprisingly well with analytical expressions derived
under first-order smoothing, although the present calculations are expected to
lie near the limits of the validity range of FOSA.


title:
Zeeman tomography of magnetic white dwarfs III. The 70-80 Megagauss
  magnetic field of PG 1015+014

abstract:
Aims: We analyse the magnetic field geometry of the magnetic DA white
dwarf PG 1015+014 with our Zeeman tomography method.
 Methods: This
study is based on rotation-phase resolved optical flux and circular
polarization spectra of PG 1015+014 obtained with FORS1 at the ESO VLT. Our
tomographic code makes use of an extensive database of pre-computed Zeeman
spectra. The general approach has been described in Papers I and II of this
series.
 Results: The surface field strength distributions for all
rotational phases of PG 1015+014 are characterised by a strong peak at 70 MG. A
separate peak at 80 MG is seen for about one third of the rotation cycle.
Significant contributions to the Zeeman features arise from regions with field
strengths between 50 and 90 MG. We obtain equally good simultaneous fits to the
observations, collected in five phase bins, for two different field
parametrizations: (i) a superposition of individually tilted and off-centred
zonal multipole components; and (ii) a truncated multipole expansion up to
degree l = 4 including all zonal and tesseral components. The magnetic fields
generated by both parametrizations exhibit a similar global structure of the
absolute surface field values, but differ considerably in the topology of the
field lines. An effective photospheric temperature of Teff = 10000
± 1000 K was found.
 Conclusions: Remaining discrepancies
between the observations and our best-fit models suggest that additional
small-scale structure of the magnetic field exists which our field models are
unable to cover due to the restricted number of free parameters.


title: Study of the cyclotron feature in MXB 0656-072

abstract:
  We have monitored a Type II outburst of the Be/X-ray binary MXB 0656-072 in a
series of pointed RXTE observations during October through December 2003. The
source spectrum shows a cyclotron resonance scattering feature at 32.8 +/- 0.5
keV, corresponding to a magnetic field strength of (3.67 +/- 0.06) x 10^12 G
and is stable through the outburst and over the pulsar spin phase. The pulsar,
with an average pulse period of 160.4 +/- 0.4 s, shows a spin-up of 0.45 s over
the duration of the outburst. From optical data, the source distance is
estimated to be 3.9 +/- 0.1 kpc and this is used to estimate the X-ray
luminosity and a theoretical prediction of the pulsar spin-up during the
outburst.


title: Water destruction by X-rays in young stellar objects

abstract:
  We study the H2O chemistry in star-forming environments under the influence
of a central X-ray source and a central far ultraviolet (FUV) radiation field.
The gas-phase water chemistry is modeled as a function of time, hydrogen
density and X-ray flux. To cover a wide range of physical environments,
densities between n_H = 10^4-10^9 cm^-3 and temperatures between T = 10-1000 K
are studied. Three different regimes are found: For T < 100 K, the water
abundance is of order 10^-7-10^-6 and can be somewhat enhanced or reduced due
to X-rays, depending on time and density. For 100 K < T < 250 K, H2O is reduced
from initial x(H2O) ~ 10^-4 following ice evaporation to x(H2O) ~ 10^-6 for F_X
> 10^-3 ergs s-1 cm^-2 (t = 10^4 yrs) and for F_X > 10^-4 ergs s^-1 cm^-2 (t =
10^5 yrs). At higher temperatures (T > 250 K) and hydrogen densities, water can
persist with x(H2O) ~ 10^-4 even for high X-ray fluxes. The X-ray and FUV
models are applied to envelopes around low-mass Class 0 and I young stellar
objects (YSOs). Water is destroyed in both Class 0 and I envelopes on
relatively short timescales (t ~ 5000 yrs) for realistic X-ray fluxes, although
the effect is less prominent in Class 0 envelopes due to the higher X-ray
absorbing densities there. FUV photons from the central source are not
effective in destroying water. The average water abundance in Class I sources
for L_X > 10^27 ergs s^-1 is predicted to be x(H2O) < 10^-6.


title: A 0535+26: Back in business

abstract:
  In May/June 2005, after 10 years of inactivity, the Be/X-ray binary system A
0535+26 underwent a major X-ray outburst. In this paper data are presented from
10 years of optical, IR and X-ray monitoring showing the behaviour of the
system during the quiescent epoch and the lead up to the new outburst. The
results show the system going through a period when the Be star in the system
had a minimal circumstellar disk and then a dramatic disk recovery leading,
presumably, to the latest flare up of X-ray emission. The data are interpreted
in terms of the state of the disk and its interaction with the neutron star
companion.


title:
Cosmic Evolution with Early and Late Acceleration Inspired by Dual
  Nature of the Ricci Scalar Curvature

abstract:
  In the present paper, it is found that dark energy emerges spontaneously from
the modified gravity. According to cosmological scenario, obtained here, the
universe inflates for $\sim 10^{-37}$ sec. in the beginning and late universe
accelerates after 8.58 Gyrs. During the long intermediate period, it
decelerates driven by radiation and subsequently by matter. Emerged
gravitational dark energy mimics quintessence and its density falls by 115
orders from its initial value $2.58\times 10^{68} {\rm GeV}^4$ to its current
value $2.19\times 10^{-47} {\rm GeV}^4$ .


title: Advanced Topics in Cosmology: A Pedagogical Introduction

abstract:
  These lecture notes provide a concise, rapid and pedagogical introduction to
several advanced topics in contemporary cosmology. The discussion of thermal
history of the universe, linear perturbation theory, theory of CMBR temperature
anisotropies and the inflationary generation of perturbation are presented in a
manner accessible to someone who has done a first course in cosmology. The
discussion of dark energy is more research oriented and reflects the personal
bias of the author. Contents: (I) The cosmological paradigm and Friedmann model
(II) Thermal history of the universe (III) Structure formation and linear
perturbation theories (IV) Perturbations in dark matter and radiation (V)
Transfer function for matter perturbations (VI) Temperature anisotropies of
CMBR (VII) Generation of initial perturbations from inflation (VIII) The dark
energy.


title: Dissipative or Conservative cosmology with dark energy ?

abstract:
  All evolutional paths for all admissible initial conditions of FRW
cosmological models with dissipative dust fluid (described by dark matter,
baryonic matter and dark energy) are analyzed using dynamical system approach.
With that approach, one is able to see how generic the class of solutions
leading to the desired property -- acceleration -- is. The theory of dynamical
systems also offers a possibility of investigating all possible solutions and
their stability with tools of Newtonian mechanics of a particle moving in a
1-dimensional potential which is parameterized by the cosmological scale
factor. We demonstrate that flat cosmology with bulk viscosity can be treated
as a conservative system with a potential function of the Chaplygin gas type.
We also confront viscous models with SNIa observations. The best fitted models
are obtained by minimizing the $\chi^{2}$ function which is illustrated by
residuals and $\chi^{2}$ levels in the space of model independent parameters.
The general conclusion is that SNIa data supports the viscous model without the
cosmological constant. The obtained values of $\chi^{2}$ statistic are
comparable for both the viscous model and LCDM model. The Bayesian information
criteria are used to compare the models with different power law
parameterization of viscous effects. Our result of this analysis shows that
SNIa data supports viscous cosmology more than the LCDM model if the
coefficient in viscosity parameterization is fixed. The Bayes factor is also
used to obtain the posterior probability of the model.


title:
The First Direct Spectroscopic Detection of a White Dwarf Primary in an
  AM CVn System

abstract:
  We report the results of a synthetic spectral analysis of Hubble STIS spectra
of the AM CVn-type cataclysmic variable CP Eri obtained when the system was in
quiescence. The FUV spectrum is best fitted by a helium-dominated, hybrid
composition (DBAZ) white dwarf with Teff=17,000K +/- 1000K, log g=8, He
abundance ~1000 times solar, H abundance ~0.1 times solar, metallicity Z ~ 0.05
times solar, V sin i = 400 km/s. This is the first directly detected primary
white dwarf in any AM CVn and the surface abundance and rotation rate for the
white dwarf primary are the first to be reported for AM CVn systems. The
model-predicted distance is ~ 1000 pc. The spectral fits using pure He
photospheres or He-rich accretion disks were significantly less successful.
Based upon the analysis of our FUV spectra, CP Eri appears to contain a hybrid
composition DBAZ white dwarf with a metallicity which sets it apart from the
other two AM Cvn stars which have been observed in quiescence and are
metal-poor. The implications of this analysis for evolutionary channels leading
to AM CVn systems are discussed.


title: A Far Ultraviolet Study of the Hot White Dwarf in the Dwarf Nova WW Ceti

abstract:
  We present a synthetic spectral analysis of IUE archival and FUSE FUV spectra
of the peculiar dwarf nova WW Ceti. During the quiescence of WW Ceti, a white
dwarf with Twd=26,000K can account for the FUV flux and yields the proper
distance. However, the best agreement with the observations is provided by a
two-temperature white dwarf model with a cooler white dwarf at Twd=25,000K
providing 75% of the FUV flux and a hotter region (accretion belt or optically
thick disk ring) with T=40,000K contributing 25% of the flux for the proper
distance. We find from the FUSE spectrum that the white dwarf is rotating with
a projected rotational velocity V sin{i} = 600 km/s. Our temperature results
provide an additional data point in the distribution of Twd versus orbital
period above the CV period gap where few Twds are available.


title:
The most metal-poor damped Ly alpha system at z<3: constraints on early
  nucleosynthesis

abstract:
  To constrain the conditions for very early nucleosynthesis in the Universe we
compare the chemical enrichment pattern of an extremely metal-poor damped Lyman
alpha (DLA) absorber with predictions from recent explosive nucleosynthesis
model calculations. For this, we have analyzed chemical abundances in the DLA
system at z_abs=2.6183 toward the quasar Q0913+072 (z_em=2.785) using public
UVES/VLT high spectral resolution data. The total neutral hydrogen column
density in this absorber is logN(HI)=20.36. Accurate column densities are
derived for CII, NI, OI, AlII, SiII, and FeII. Upper limits are given for FeIII
and NiII. With [C/H]=-2.83, [N/H]=-3.84, and [O/H]=-2.47, this system
represents one of the most metal-poor DLA systems investigated so far. It
offers the unique opportunity to measure accurate CNO abundances in a
protogalactic structure at high redshift. Given the very low overall abundance
level and the observed abundance pattern, the data suggest that the chemical
evolution of this DLA system is dominated by one or at most a few stellar
generations. With reference to numerical model calculations, the chemical
abundances in the DLA system are consistent with an enrichment from a single
starburst of a zero-metallicity population of massive stars (10-50 M_sun)
exploding as core-collapse Supernovae (SNe), i.e., the classical Type II
Supernovae (SNeII), and possibly as hyper-energetic (E>10^51erg) core-collapse
Supernovae, so-called Hypernovae (HNe), as well. In contrast, models using
non-zero metallicity progenitors or other explosion mechanisms, such as
pair-instability Supernovae (PISNe) or Type Ia Supernovae (SNeIa), do not match
the observed abundance pattern.


title:
Not Alone: Tracing the Origins of Very Low Mass Stars and Brown Dwarfs
  Through Multiplicity Studies

abstract:
  The properties of multiple stellar systems have long provided important
empirical constraints for star formation theories, enabling (along with several
other lines of evidence) a concrete, qualitative picture of the birth and early
evolution of normal stars. At very low masses (VLM; M <~ 0.1 M_sun), down to
and below the hydrogen burning minimum mass, our understanding of formation
processes is not as clear, with several competing theories now under
consideration. One means of testing these theories is through the empirical
characterization of VLM multiple systems. Here, we review the results of
various VLM multiplicity studies to date. These systems can be generally
characterized as closely separated (93% have projected separations Delta < 20
AU) and near equal-mass (77% have M_2/M_1 >= 0.8) occurring infrequently
(perhaps 10-30%). Both the frequency and maximum separation of stellar and
brown dwarf binaries steadily decrease for lower system masses, suggesting that
VLM binary formation and/or evolution may be a mass-dependent process. There is
evidence for a fairly rapid decline in the number of loosely-bound systems
below ~0.3 M_sun, corresponding to a factor of 10-20 increase in the minimum
binding energy of VLM binaries as compared to more massive stellar binaries.
This wide-separation ``desert'' is present among both field (~1-5 Gyr) and
older (> 100 Myr) cluster systems, while the youngest (<~10 Myr) VLM binaries,
particularly those in nearby, low-density star forming regions, appear to have
somewhat different systemic properties. We compare these empirical trends to
predictions laid out by current formation theories, and outline future
observational studies needed to probe the full parameter space of the lowest
mass multiple systems.


title:
Analysis and modeling of high temporal resolution spectroscopic
  observations of flares on AD Leo

abstract:
  We report the results of a high temporal resolution spectroscopic monitoring
of the flare star AD Leo. During 4 nights, more than 600 spectra were taken in
the optical range using the Isaac Newton Telescope (INT) and the Intermediate
Dispersion Spectrograph (IDS). We have observed a large number of short and
weak flares occurring very frequently (flare activity > 0.71 hours-1). This is
in favour of the very important role that flares can play in stellar coronal
heating. The detected flares are non white-light flares and, though most of
solar flares belong to this kind, very few such events had been previously
observed on stars. The behaviour of different chromospheric lines (Balmer
series from H_alpha to H_11, Ca II H & K, Na I D_1 & D_2, He I 4026 AA and He I
D_3) has been studied in detail for a total of 14 flares. We have also
estimated the physical parameters of the flaring plasma by using a procedure
which assumes a simplified slab model of flares. All the obtained physical
parameters are consistent with previously derived values for stellar flares,
and the areas - less than 2.3% of the stellar surface - are comparable with the
size inferred for other solar and stellar flares. Finally, we have studied the
relationships between the physical parameters and the area, duration, maximum
flux and energy released during the detected flares.


title:
Voigt Profile Fitting to Quasar Absorption Lines: An Analytic
  Approximation to the Voigt-Hjerting Function

abstract:
  The Voigt-Hjerting function is fundamental in order to correctly model the
profiles of absorption lines imprinted in the spectra of bright background
sources by intervening absorbing systems. In this work we present a simple
analytic approximation to this function in the context of absorption line
profiles of intergalactic HI absorbers. Using basic calculus tools, we derive
an analytic expression for the Voigt-Hjerting function that contains only
fourth order polynomial and Gaussian functions. In connection with the
absorption coefficient of intergalactic neutral hydrogen, this approximation is
suitable for modeling Voigt profiles with an accuracy of $10^{-4}$ or better
for an arbitrary wavelength baseline, for column densities up to $N_{HI} =
10^{22} cm^{-2}$, and for damping parameters $a \lesssim 10^{-4}$, i.e. the
entire range of parameters characteristic to all Lyman transitions arising in a
variety of HI absorbing systems such as Lyman Alpha Forest clouds, Lyman Limit
systems and Damped Lyman Alpha systems. We hence present an approximation to
the Voigt-Hjerting function that is both accurate and flexible to implement in
various types of programming languages and machines, and with which Voigt
profiles can be calculated in a reliable and very simple manner.


title: Dynamics of compact objects clusters: A post-Newtonian study

abstract:
  Compact object clusters are likely to exist in the centre of some galaxies
because of mass segregation. The high densities and velocities reached in them
deserves a better understanding. The formation of binaries and their subsequent
merging by gravitational radiation emission is important to the evolution of
such clusters. We address the evolution of such a system in a relativistic
regime. The recurrent mergers at high velocities create an object with a mass
much larger than the average. For this aim we modified the direct {\sc
Nbody6}++ code to include post-Newtonian effects to the force during two-body
encounters. We adjusted the equations of motion to include for the first time
the effects of both periastron shift and energy loss by emission of
gravitational waves and so to study the eventual decay and merger of radiating
binaries. The method employed allows us to give here an accurate post-Newtonian
description of the formation of a run-away compact object by successive mergers
with surrounding particles, as well as the distribution of characteristic
eccentricities in the events. This study should be envisaged as a first step
towards a detailed, accurate study of possible gravitational waves sources
thanks to the combination of the direct {\sc Nbody} numerical tool with the
implementation of post-Newtonian terms on it.


title: The Dwarf Novae During Quiescence

abstract:
  We present a synthetic spectral analysis of nearly the entire FUV IUE archive
of spectra of DNe in or near quiescence. We have examined all of the systems
for which S/N permitted an analysis. The study includes 53 systems of all DN
subtypes both above and below the period gap. The spectra were uniformly
analyzed using synthetic spectral codes for optically thick accretion disks and
stellar photospheres along with the best-available distance measurements or
estimates. We present newly determined approximate WD temperatures or upper
limits and estimated accretion rates. The average temperature of WDs in DNe
below the period gap is ~18,000K. For WDs in DNe above the period gap, the
average WD temperature is ~26,000K. There is a flux component, in addition to a
WD photosphere, which contributes >60% of the flux in the FUV in 53% of the
quiescent DNe in this study. We find that for 41% of the DNe in our sample, a
WD photosphere provides >60% of the FUV flux. Accretion rates estimated from
the FUV alone for the sample of DNe during quiescence ranged from 10^-12
Msun/yr to 10^-10 Msun/yr.The additional flux component is almost certainly not
an optically thick accretion disk since, according to the disk instability
model, the disk should be optically thin and too cool during DN quiescence to
be a significant FUV continuum emitter. Among the candidates for the second
component of FUV light are the quiescent inner disk, a hot equatorial accretion
belt, and a hot rotating ring. The implications of our study for disk accretion
physics and CV evolution are discussed.


title: X-ray spectral properties of AGN in the Chandra Deep Field South

abstract:
  We present a detailed X-ray spectral analysis of the sources in the 1Ms
catalog of the Chandra Deep Field South (CDFS) taking advantage of optical
spectroscopy and photometric redshifts for 321 sources. As a default spectral
model, we adopt a power law with slope Gamma with an intrinsic redshifted
absorption N_H, a fixed Galactic absorption and an unresolved Fe emission line.
For 82 X-ray bright sources, we perform the X-ray spectral analysis leaving
both Gamma and N_H free. The weighted mean value is <Gamma>~ 1.75+-0.02, with
an intrinsic dispersion of sigma~0.30. We do not find hints of a correlation
between Gamma and the N_H. We detect the presence of a scattered component at
soft energies in 8 sources, and a pure reflection spectrum, typical of
Compton-thick AGN, in 14 sources (Compton-thick AGN candidates). The intrinsic
N_H distribution shows a lognormal shape, peaking around log(N_H)~23.1 and with
sigma~1.1. We find that the fraction of absorbed sources (with N_H>10^{22}
cm^{-2}) in the sample is constant (at the level of about 75%) or moderately
increasing with redshift. Finally, we compare the optical classification to the
X-ray spectral properties, confirming that the correspondence of unabsorbed
(absorbed) X-ray sources to optical Type I (Type II) AGN is accurate for at
least 80% of the sources with spectral identification (1/3 of the total X-ray
sample).


title:
A Survey of Local Group Galaxies Currently Forming Stars. I. UBVRI
  Photometry of Stars in M31 and M33

abstract:
  We present UBVRI photometry obtained from Mosaic images of M31 and M33 using
the KPNO 4-m telescope. The survey covers 2.2 sq degrees of M31, and 0.8 sq
degrees of M33, chosen so as to include all of the regions currently active in
forming massive stars. The catalog contains 371,781 and 146,622 stars in M31
and M33, respectively, where every star has a counterpart (at least) in B, V,
and R. We compare our photometry to previous studies. We provide cross
references to the stars confirmed as members by spectroscopy, and compare the
location of these to the complete set in color-magnitude diagrams. While
follow-up spectroscopy is needed for many projects, we demonstrate the success
of our photometry in being able to distinguish M31/M33 members from foreground
Galactic stars. We also present the results of newly obtained spectroscopy,
which identifies 34 newly confirmed members, including B-A supergiants, the
earliest O star known in M31, and two new Luminous Blue Variable candidates
whose spectra are similar to that of P Cygni.


title: The uncombed penumbra

abstract:
  The uncombed penumbral model explains the structure of the sunspot penumbra
in terms of thick magnetic fibrils embedded in a magnetic surrounding
atmosphere. This model has been successfully applied to explain the
polarization signals emerging from the sunspot penumbra. Thick penumbral
fibrils face some physical problems, however. In this contribution we will
offer possible solutions to these shortcomings.


title: Magnetic field vector retrieval with HMI

abstract:
  The Helioseismic and Magnetic Imager (HMI), on board the Solar Dynamics
Observatory (SDO), will begin data acquisition in 2008. It will provide the
first full disk, high temporal cadence observations of the full Stokes vector
with a 0.5 arc sec pixel size. This will allow for a continuous monitoring of
the Solar magnetic field vector. HMI data will advance our understanding of the
small and large-scale magnetic field evolution, its relation to the solar and
global dynamic processes, coronal field extrapolations, flux emergence,
magnetic helicity and the nature of the polar magnetic fields. We summarize
HMI's expected operation modes, focusing on the polarization cross-talk induced
by the solar oscillations and how this affects the magnetic field vector
determinations.


title:
An ultradeep submillimetre map: beneath the SCUBA confusion limit with
  lensing and robust source extraction

abstract:
  Extracting sources with low signal-to-noise from maps with structured
background is a non-trivial task which has become important in studying the
faint end of the submillimetre number counts. In this article we study source
extraction from submillimetre jiggle-maps from the Submillimetre Common-User
Bolometer Array (SCUBA) using the Mexican Hat Wavelet (MHW), an isotropic
wavelet technique. As a case study we use a large (11.8 arcmin^2) jiggle-map of
the galaxy cluster Abell 2218, with a 850um 1sigma r.m.s. sensitivity of
0.6-1mJy. We show via simulations that MHW is a powerful tool for reliable
extraction of low signal-to-noise sources from SCUBA jiggle-maps and nine
sources are detected in the A2218 850um image. Three of these sources are
identified as images of a single background source with an unlensed flux of
0.8mJy. Further, two single-imaged sources also have unlensed fluxes <2mJy,
below the blank-field confusion limit. In this ultradeep map, the individual
sources detected resolve nearly all of the extragalactic background light at
850um, and the deep data allow to put an upper limit of 44 sources per arcmin^2
to 0.2mJy at 850um.


title: Astroparticle Physics with High Energy Neutrinos: from AMANDA to IceCube

abstract:
  Kilometer-scale neutrino detectors such as IceCube are discovery instruments
covering nuclear and particle physics, cosmology and astronomy. Examples of
their multidisciplinary missions include the search for the particle nature of
dark matter and for additional small dimensions of space. In the end, their
conceptual design is very much anchored to the observational fact that Nature
produces protons and photons with energies in excess of $10^{20}$\,eV and
$10^{13}$\,eV, respectively. The puzzle of where and how Nature accelerates the
highest energy cosmic particles is unresolved almost a century after their
discovery. The cosmic ray connection sets the scale of cosmic neutrino fluxes.
In this context, we discuss the first results of the completed AMANDA detector
and the science reach of its extension, IceCube. Similar experiments are under
construction in the Mediterranean. Neutrino astronomy is also expanding in new
directions with efforts to detect air showers, acoustic and radio signals
initiated by super-EeV neutrinos. The outline of this review is as follows:
  Introduction
  Why Kilometer-Scale Detectors?
  Cosmic Neutrinos Associated with the Highest Energy Cosmic Rays
  High Energy Neutrino Telescopes: Methodologies of Neutrino Detection
  High Energy Neutrino Telescopes: Status


title: Detecting neutrino mass difference with cosmology

abstract:
  Cosmological parameter estimation exercises usually make the approximation
that the three standard neutrinos have degenerate mass, which is at odds with
recent terrestrial measurements of the difference in the square of neutrino
masses. In this paper we examine whether the use of this approximation is
justified for the cosmic microwave background (CMB) spectrum, matter power
spectrum and the CMB lensing potential power spectrum. We find that, assuming
m^2_{23} ~ 2.5x10^{-3}$eV^2 in agreement with recent Earth based measurements
of atmospheric neutrino oscillations, the correction due to non-degeneracy is
of the order of precision of present numerical codes and undetectable for the
foreseeable future for the CMB and matter power spectra. An ambitious
experiment that could reconstruct the lensing potential power spectrum to the
cosmic variance limit up to l~1000 will have to take the effect into account in
order to avoid biases. The degeneracies with other parameters, however, will
make the detection of the neutrino mass difference impossible. We also show
that relaxing the bound on the neutrino mass difference will also increase the
error-bar on the sum of neutrino masses by a factor of up to a few. For exotic
models with significantly non-degenerate neutrinos the corrections due to
non-degeneracy could become important for all the cosmological probes discussed
here.


title: The Generation of Magnetic Fields and X-ray Observations

abstract:
  We show that strong magnetic fields can be generated at shock waves
associated with formation of galaxies or clusters of galaxies by the Weibel
instability, an instability in collisionless plasmas. The estimated strength of
the magnetic field generated through this mechanism is close to the order of
values observed in galaxies or clusters of galaxies at present, which indicates
that strong amplification of magnetic fields after formation of galaxies or
clusters of galaxies is not required. This mechanism could have worked even at
a redshift of ~10, and therefore the generated magnetic fields may have
affected the formation of stars at the early universe. This model will be
confirmed by future observations of nearby clusters of galaxies. In this
context, we also present the Japanese X-ray missions.


title:
Late-Time X-ray Flares during GRB Afterglows: Extended Internal Engine
  Activity

abstract:
  Observations of gamma ray bursts (GRBs) with Swift produced the initially
surprising result that many bursts have large X-ray flares superimposed on the
underlying afterglow. These flares were sometimes intense, rapid, and late
relative to the nominal prompt phase. The most intense of these flares was
observed by XRT with a flux >500 the afterglow. This burst then surprised
observers by flaring again after >10000 s. The intense flare can be most easily
understood within the context of the standard fireball model, if the internal
engine that powers the prompt GRB emission is still active at late times.
Recent observations indicate that X-ray flares are detected in ~1/3 of XRT
detected afterglows. By studying the properties of the varieties of flares
(such as rise/fall time, onset time, spectral variability, etc.) and relating
them to overall burst properties, models of flare production and the GRB
internal engine can be constrained.


title:
A stellar companion in the HD 189733 system with a known transiting
  extrasolar planet

abstract:
  We show that the very close-by (19 pc) K0 star HD 189733, already found to be
orbited by a transiting giant planet, is the primary of a double-star system,
with the secondary being a mid-M dwarf with projected separation of about 216
AU from the primary. This conclusion is based on astrometry, proper motion and
radial velocity measurements, spectral type determination and photometry. We
also detect differential proper motion of the secondary. The data appear
consistent with the secondary orbiting the primary in a clockwise orbit, lying
nearly in the plane of the sky (that is, nearly perpendicular to the orbital
plane of the transiting planet), and with period about 3200 years.


title:
Deciphering Inflation with Gravitational Waves: Cosmic Microwave
  Background Polarization vs. Direct Detection with Laser Interferometers

abstract:
  A detection of the primordial gravitational wave background is considered to
be the ``smoking-gun '' evidence for inflation. While super-horizon waves are
probed with cosmic microwave background (CMB) polarization, the relic
background will be studied with laser interferometers. The long lever arm
spanned by the two techniques improves constraints on the inflationary
potential and validation of consistency relations expected under inflation. If
gravitational waves with a tensor-to-scalar amplitude ratio greater than 0.01
are detected by the CMB, then a direct detection experiment with a sensitivity
consistent with current concept studies should be pursued vigorously. If no
primordial tensors are detected by the CMB, a direct detection experiment to
understand the simplest form of inflation must have a sensitivity improved by
two to three orders of magnitude over current plans.


title:
Recent Developments in Neutron Star Thermal Evolution Theories and
  Observation

abstract:
  Recent years have seen some significant progress in theoretical studies of
physics of dense matter. Combined with the observational data now available
from the successful launch of Chandra and XMM/Newton X-ray space missions as
well as various lower-energy band observations, these developments now offer
the hope for distinguishing various competing neutron star thermal evolution
models. For instance, the latest theoretical and observational developments may
already exclude both nucleon and kaon direct Urca cooling. In this way we can
now have a realistic hope for determining various important properties, such as
the composition, superfluidity, the equation of state and stellar radius. These
developments should help us obtain deeper insight into the properties of dense
matter.


title:
Contact Binaries with Additional Components. II. A Spectroscopic Search
  for Faint Tertiaries

abstract:
  It is unclear how very close binary stars form, given that during the
pre-main-sequence phase the component stars would have been inside each other.
One hypothesis is that they formed further apart, but were brought in closer
after formation by gravitational interaction with a third member of the system.
If so, all close binaries should be members of triple (or higher-order)
systems. As a test of this prediction, we present a search for the signature of
third components in archival spectra of close binaries. In our sample of 75
objects, 23 show evidence for the presence of a third component, down to a
detection limit of tertiary flux contributions of about 0.8% at 5200 \AA\
(considering only contact and semi-detached binaries, we find 20 out of 66). In
a homogeneous subset of 58 contact binaries, we are fairly confident that the
15 tertiaries we have detected are all tertiaries present with mass ratios
$0.28\lesssim M_3/M_{12}\lesssim0.75$ and implied outer periods
$P\lesssim10^6{\rm d}$. We find that if the frequency of tertiaries was the
same as that of binary companions to solar-type stars, we would have expected
to detect about 12 tertiaries. In contrast, if all contact binaries were in
triple systems, one would expect about 20. Thus, our results are not
conclusive, but sufficiently suggestive to warrant further studies.


title:
The colour-magnitude relations of ClJ1226.9+3332, a massive cluster of
  galaxies at z=0.89

abstract:
  (Abridged) The colour-magnitude relations of one of the most massive, high
redshift clusters of galaxies known have been studied. Photometry has been
measured in the V, R, I, z, F606W, F814W, J and K bands to a depth of K*+2.5
and spectroscopy confirms 27 K band selected cluster members. The V-K colours
are equivalent to a rest-frame colour of ~2700A-J, and provide a very sensitive
measure of star-formation activity. HST ACS imaging has been used to
morphologically classify the galaxies.
  The cluster has a low early-type fraction compared to nearby clusters, with
only 33% of the cluster members having types E or S0. The early-type member
galaxies form a clear red-sequence in all colours. The scatter and slope of the
relations show no evolution compared to the equivalent Coma cluster relations,
suggesting the stellar populations are already very old. The normalisation of
the relations has been compared to models based on synthetic stellar
populations, and are most consistent with stellar populations forming at z>3.
Some late-type galaxies were found to lie on the red-sequence, suggesting that
they have very similar stellar populations to the early-types.
  These results present a picture of a cluster in which the early-type galaxies
are all old, but in which there must be future morphological transformation of
galaxies to match the early-type fraction of nearby clusters. In order to
preserve the tight colour-magnitude relation of early-types seen in nearby
clusters, the late-type galaxies must transform their colours, through the
cessation of star-formation, before the morphological transformation occurs.
Such evolution is observed in the late-types lying on the colour-magnitude
relation.


title:
An implicit method for radiative transfer with the diffusion
  approximation in SPH

abstract:
  An implicit method for radiative transfer in SPH is described. The diffusion
approximation is used, and the hydrodynamic calculations are performed by a
fully three--dimensional SPH code. Instead of the energy equation of state for
an ideal gas, various energy states and the dissociation of hydrogen molecules
are considered in the energy calculation for a more realistic temperature and
pressure determination. In order to test the implicit code, we have performed
non--isothermal collapse simulations of a centrally condensed cloud, and have
compared our results with those of finite difference calculations performed by
MB93. The results produced by the two completely different numerical methods
agree well with each other.


title:
Testing the Curvature Effect and Internal Origin of Gamma-Ray Burst
  Prompt Emissions and X-ray Flares with Swift Data

abstract:
  The X-ray light curves of many gamma-ray bursts (GRBs) observed by the Swift
X-Ray Telescope (XRT) have a very steep-decay component (tail) following the
prompt gamma-rays in the early phase and have some erratic flares occurring at
a time from ~10^2 up to ~10^5 seconds. Based on the assumption that these tails
and flares are of internal shock origin and that their decline behaviors are
dominated by the curvature effect of the fireball, we present a
self-consistency test for this scenario with a sample of 36
prompt-emission-tails/flare-tails in 22 GRB XRT light curves. Our results show
that the t0 of the prompt emission tails and the tails of well-separated flares
are usually at the rising segment of the last pulse of the prompt emission or
the corresponding X-ray flare, being self-consistent with the expectation of
the internal dissipation models for the prompt emission and X-ray flares. Our
results indicate that each X-ray flare forms a distinct new episode of central
engine activity and the GRB central engine remains active after the prompt
emission is over, sometimes up to ~1 day after the GRB trigger (e.g. GRB
050502B & GRB 050724). This challenges the conventional central engine models
and calls for new ideas to re-start the central engine. We further show that
the on-set time of the late central engine activity does not depend on the GRB
duration. We also identify a minority group of GRBs whose combined BAT-XRT
light curves are smoothly connected without an abrupt transition between the
prompt emission and the afterglow. These GRBs may have an external origin for
both the prompt emission and the afterglow.


title:
Infrared 3-4 Micron Spectroscopy of Infrared Luminous Galaxies with
  Possible Signatures of Obscured Active Galactic Nuclei

abstract:
  We present the results of infrared 2.8-4.1 micron (L-band) spectroscopy of
nearby infrared luminous galaxies with possible signatures of dust-obscured
active galactic nuclei (AGNs) in data at other wavelengths. The samples are
chosen to include sources with a radio excess relative to far-infrared
emission, strong absorption features in mid-infrared 5-11.5 micron spectra,
unusually weak [CII] 158 micron emission relative to the far-infrared
continuum, and radio galaxies classified optically as narrow-line objects. Our
aim is to investigate whether the signatures of possible obscured AGNs can be
detected in our L-band spectra, based on the strengths of emission and
absorption features. Six of nine observed sources clearly show 3.3 micron
polycyclic aromatic hydrocarbon (PAH) emission features, a good starburst
indicator. An absorption feature at 3.1 micron due to ice-covered dust is
detected in IRAS 04154+1755 and IRAS 17208-0014. The signature of a bare
carbonaceous dust absorption feature at 3.4 micron is seen in NGC 1377. Our
L-band spectra reveal strong signatures of obscured AGNs in all three optical
Seyfert 2 galaxies (IRAS 04154+1755, Cygnus A, and 3C 234), and two galaxies
classified optically as non-Seyferts (NGC 828 and NGC 1377). Among the
remaining optical non-Seyferts, IRAS 17208-0014 might also show a buried AGN
signature, whereas no explicit AGN evidence is seen in the L-band spectra of
the mid-infrared absorption-feature source IRAS 15250+3609, and two weak [CII]
emitters IC 860 and CGCG 1510.8+0725.


title: GRB Afterglows as a New Probe of the ISM and IGM at High Redshift

abstract:
  We summarize results from a study of the metallicity, relative abundances,
gas density, and kinematics of dense media in the host environment of two Swift
bursts, GRB050730 at z=3.968 and GRB051111 at z=1.549. Both GRB hosts exhibit
strong absorption features from excited Si+ and Fe+ ions, indicating an extreme
ISM environment that is similar to what is found around massive stars like
luminous blue variables (LBV) and Wolf-Rayet stars. The extreme ISM properties
have never been observed in intervening quasar absorption line systems beyond
the local universe.


title:
Investigating the nature of narrow-line Seyfert 1 galaxies with
  high-energy spectral complexity

abstract:
  (abridged) With the commissioning of XMM came the discovery of 2.5-10 keV
spectral complexity in some narrow-line Seyfert 1 galaxies (NLS1). In this
work, we define two samples of NLS1: a complex sample whose members exhibit
high-energy complexity (C-sample), and a general sample of NLS1 whose 2.5-10
keV spectra do not strongly deviate from a simple power law (S-sample).
Considering historical light curves of each object we find that the C-sample is
representative of NLS1 in a low X-ray flux state, whereas the members of the
S-sample appear to be in a typical flux state. Moreover, from measurements of
alpha_ox with contemporaneous UV/X-ray data, we find that the C-sample of NLS1
appear X-ray weaker at the time of the observation. For two NLS1 in the
C-sample multi-epoch measurements of alpha_ox are available and suggest that
alpha_ox approaches more normal values as the complexity between 2.5-10 keV
diminishes. This implies that a source could transit from one sample to the
other as its X-ray flux varies. Secondly, there are indications that the
C-sample sources, on average, exhibit stronger optical FeII emission, with the
three most extreme (FeII/H_beta > 1.8) FeII emitters all displaying complexity
in the 2.5-10 keV band. However, it is not clear if the possible connection
between FeII strength and spectral complexity is due to the FeII producing
mechanism or because strong FeII emitters may exhibit the greatest variability
and consequently more likely to be caught in an extreme (low) flux state. Based
on the current analysis it we can not straightforwardly dismiss absorption or
reflection as the cause of the X-ray complexity.


title: Discovery of an Extraordinarily Massive Cluster of Red Supergiants

abstract:
  We report the discovery of an extraordinarily massive young cluster of stars
in the Galaxy, having an inferred total initial cluster mass comparable to the
most massive young clusters in the Galaxy. Using {\it IRMOS}, {\it 2MASS}, and
{\it Spitzer} observations, we conclude that there are 14 red supergiants in
the cluster, compared with five, in what was previously thought to be the
richest Galactic cluster of such stars. We infer spectral types from
near-infrared spectra that reveal deep CO bandhead absorption that can only be
fit by red supergiants. We identify a gap of $\Delta${\it K}$_s$$\sim$4
magnitudes between the stars and the bulk of the other stars in the region that
can only be fit by models if the brightest stars in the cluster are red
supergiants. We estimate a distance of 5.8~\kpc to the cluster by associating
an OH maser with the envelope of one of the stars. We also identify a
``yellow'' supergiant of G6~I type in the cluster. Assuming a Salpeter IMF, we
infer an initial cluster mass of 20,000 to 40,000~\Msun for cluster ages of
7-12~\Myr. Continuing with these assumptions, we find 80% of the intial mass
and 99% of the number of stars remain at the present time. We associate the
cluster with an x-ray source (detected by {\it ASCA} and {\it Einstein}), a
recently discovered very high energy $\gamma$-ray source (detected by {\it
INTEGRAL} and {\it HESS}), and several non-thermal radio sources, finding that
these objects are likely related to recent supernovae in the cluster. In
particular, we claim that the cluster has produced at least one recent
supernova remnant with properties similar to the Crab nebula. It is not
unlikely to find such a source in this cluster, given our estimated supernova
rate of one per 40,000 to 80,000~{\it yr}.


title: Likelihood Methods for Cluster Dark Energy Surveys

abstract:
  Galaxy cluster counts at high redshift, binned into spatial pixels and binned
into ranges in an observable proxy for mass, contain a wealth of information on
both the dark energy equation of state and the mass selection function required
to extract it. The likelihood of the number counts follows a Poisson
distribution whose mean fluctuates with the large-scale structure of the
universe. We develop a joint likelihood method that accounts for these
distributions. Maximization of the likelihood over a theoretical model that
includes both the cosmology and the observable-mass relations allows for a
joint extraction of dark energy and cluster structural parameters.


title: Short term variability in Be stars and binaries in the Magellanic Clouds

abstract:
  We observed a large sample of B & Be stars in the Magellanic Clouds,
respectively 176 and 344 stars, with the multi-object spectrograph GIRAFFE at
ESO/VLT. We obtained spectra at different settings at various epochs. It
allowed us to discover several spectroscopic binaries with short and
intermediate periods. By cross-correlation in coordinates with the MACHO
database, we found the light-curves for 350 stars in our samples. Among them,
19 (14 new) are photometric binaries (5 in the LMC, 14 in the SMC). Among these
19 photometric binaries 6 are also spectroscopic binaries (5 in the LMC, 1 in
the SMC) and 2 others are Be stars (2 in the SMC). For all these binaries the
orbital period was determined. Among our sample, 134 Be stars were observed by
MACHO and, for these stars, we searched for short-term photometric variability.
We have found 13 objects among Be stars in the SMC which present short-term
photometric variability (P$<$2.5d) with amplitude lower than 0.1 magnitude.
This short-term variability is often superimposed to a long-term variation.


title:
Effects of metallicity, star formation conditions and evolution of B &
  Be stars

abstract:
  To study the effects of metallicity and evolution on the appearance of the Be
phenomenon in the B stars population, we observed several fields in the Large
and Small Magellanic Clouds (LMC and SMC, respectively) which have different
metallicities. Thanks to the FLAMES-GIRAFFE multi-fibres spectrograph on the
VLT-UT2, we obtained spectra of 520 stars in the LMC-NGC2004 and SMC-NGC330
regions. We used 2 settings at medium resolution: R=8600 for the red setting
which contains H$\alpha$ and R=6400 for the blue setting which contains
H$\gamma$, H$\delta$, \ion{He}{I} 4026, 4388, 4471 \AA. The latter setting was
used to obtain fundamental parameters of the stars by fitting the observed
spectrum with theoretical spectra. We used TLUSTY (Hubeny & Lanz 1995) to
compute a grid of model atmospheres with abundance adopted from Korn et al.
(2002) for the LMC and from Jasniewicz & Th\'evenin (1994) for the SMC. Thanks
to the GIRFIT code (Fr\'emat et al. 2005a), we obtained the fundamental
parameters \teff, \logg, \vsini~and radial velocity (RV) for each star of the
samples.We took into account the effects of fast rotation (stellar flattening
and gravitational darkening) for Be stars to correct their apparent fundamental
parameters. Then we compared the rotational velocities between fields and
clusters in the SMC and in the LMC respectively, between the LMC and the SMC,
and between the MC and the Milky Way (MW). The results show an increase in
Vsini with decreasing metallicity in B and Be stars populations. The
evolutionary status and ages of Be stars were also investigated.


title: A model for atomic and molecular interstellar gas: The Meudon PDR code

abstract:
  We present the revised ``Meudon'' model of Photon Dominated Region (PDR
code), presently available on the web under the Gnu Public Licence at:
http://aristote.obspm.fr/MIS. General organisation of the code is described
down to a level that should allow most observers to use it as an interpretation
tool with minimal help from our part. Two grids of models, one for low
excitation diffuse clouds and one for dense highly illuminated clouds, are
discussed, and some new results on PDR modelisation highlighted.