title:
Integrated Sachs-Wolfe effect from the cross correlation of WMAP3 year
  and the NRAO VLA sky survey data: New results and constraints on dark energy

abstract:
  We cross-correlate the new 3 year Wilkinson Microwave Anistropy Probe (WMAP)
cosmic microwave background (CMB) data with the NRAO VLA Sky Survey (NVSS)
radio galaxy data, and find further evidence of late integrated Sachs-Wolfe
(ISW) effect taking place at late times in cosmic history. Our detection makes
use of a novel statistical method \cite{Baldi et al. 2006a, Baldi et al. 2006b}
based on a new construction of spherical wavelets, called needlets. The null
hypothesis (no ISW) is excluded at more than 99.7% confidence. When we compare
the measured cross-correlation with the theoretical predictions of standard,
flat cosmological models with a generalized dark energy component parameterized
by its density, $\omde$, equation of state $w$ and speed of sound $\cs2$, we
find $0.3\leq\omde\leq0.8$ at 95% c.l., independently of $\cs2$ and $w$. If
dark energy is assumed to be a cosmological constant ($w=-1$), the bound on
density shrinks to $0.41\leq\omde\leq 0.79$. Models without dark energy are
excluded at more than $4\sigma$. The bounds on $w$ depend rather strongly on
the assumed value of $\cs2$. We find that models with more negative equation of
state (such as phantom models) are a worse fit to the data in the case $\cs2=1$
than in the case $\cs2=0$.


title:
Multicolour Optical Surface Brightness Profiles Decomposition of the
  Seyfert Galaxies III Zw 2, Mrk 506 and Mrk 509

abstract:
  We present the results of the UBVRcIc surface brightness profiles
decomposition of the Seyfert galaxies III Zw 2, Mrk 506 and Mrk 509. The
profiles were modelled as a sum of a Gaussian, a Sersic law and an exponent. A
Ferrers bar and a Gaussian ring were added to the model profiles of III Zw 2
and Mrk 506, respectively. The parameters and the total magnitudes of the
structural components were derived.


title: Rotation of Cosmic Voids and Void-Spin Statistics

abstract:
  We present a theoretical study of void spins and their correlation
properties. The concept of the spin angular momentum for an unbound void is
introduced to quantify the effect of the tidal field on the distribution of
matter that make up the void. Both the analytical and numerical approaches are
used for our study. Analytically, we adopt the linear tidal torque model to
evaluate the void spin-spin and spin-density correlations, assuming that a void
forms in the initial region where the inertia momentum and the tidal shear
tensors are maximally uncorrelated with each other. Numerically, we use the
Millennium run galaxy catalog to find voids and calculate their spin
statistics. The numerical results turn out to be in excellent agreement with
the analytic predictions, both of which consistently show that there are strong
spatial alignments between the spin axes of neighbor voids and strong
anti-alignments between the void spin axes and the directions to the nearest
voids. We expect that our work will provide a deeper insight into the origin
and properties of voids and the large scale structure.


title:
Statistical Analysis of Point-like Sources in Chandra Galactic Center
  Survey

abstract:
  {\it Chandra} Galactic Center Survey detected $\sim 800$ X-ray point-like
sources in the $2^{\circ} \times 0.8^{\circ}$ sky region around the Galactic
Center. In this paper, we study the spatial and luminosity distributions of
these sources according to their spectral properties. Fourteen bright sources
detected are used to fit jointly an absorbed power-law model, from which the
power-law photon index is determined to be $\sim$2.5. Assuming that all other
sources have the same power-law form, the relation between hardness ratio and
HI column density $N_H$ is used to estimate the $N_H$ values for all sources.
Monte Carlo simulations show that these sources are more likely concentrated in
the Galactic center region, rather than distributed throughout the Galactic
disk. We also find that the luminosities of the sources are positively
correlated with their HI column densities, i.e. a more luminous source has a
higher HI column density. From this relation, we suggest that the X-ray
luminosity comes from the interaction between an isolated old neutron star and
interstellar medium (mainly dense molecular clouds). Using the standard Bondi
accretion theory and the statistical information of molecular clouds in the
Galactic center, we confirm this positive correlation and calculate the
luminosity range in this scenario, which is consistent with the observation
($10^{32}\sim 10^{35}$ ergs s$^{-1}$).


title:
The Excitation of N$_2$H$^+$ in Interstellar Molecular Clouds. I -
  Models

abstract:
  We present LVG and non-local radiative transfer calculations involving the
rotational and hyperfine structure of the spectrum of N$_2$H$^+$ with
collisional rate coefficients recently derived by us. The goal of this study is
to check the validity of the assumptions made to treat the hyperfine structure
and to study the physical mechanisms leading to the observed hyperfine
anomalies.
  We find that the usual hypothesis of identical excitation temperatures for
all hyperfine components of the $J$=1-0 transition is not correct within the
range of densities existing in cold dense cores, i.e., a few 10$^4$ $\textless$
n(H$_2$) $\textless$ a few 10$^6$ cm$^{-3}$. This is due to different radiative
trapping effects in the hyperfine components. Moreover, within this range of
densities and considering the typical abundance of N$_2$H$^+$, the total
opacity of rotational lines has to be derived taking into account the hyperfine
structure. The error made when only considering the rotational energy structure
can be as large as 100%. Using non-local models we find that, due to
saturation, hyperfine anomalies appear as soon as the total opacity of the
$J$=1-0 transition becomes larger than $\simeq$ 20. Radiative scattering in
less dense regions enhance these anomalies, and particularly, induce a
differential increase of the excitation temperatures of the hyperfine
components. This process is more effective for the transitions with the highest
opacities for which emerging intensities are also reduced by self-absorption
effects. These effects are not as critical as in HCO$^+$ or HCN, but should be
taken into account when interpreting the spatial extent of the N$_2$H$^+$
emission in dark clouds.


title:
Thermal and non-thermal components of the interstellar medium at
  sub-kiloparsec scales in galaxies

abstract:
  Aims: We present new radio continuum observations of ten BIMA SONG galaxies,
taken at 1.4 GHz with the Very Large Array. These observations allow us to
extend the study of the relationships between the radio continuum (RC) and CO
emission to 22 CO luminous galaxies for which single dish CO images have been
added to interferometric data. New Spitzer infrared (IR) images of six of these
galaxies have been released. The analysis of these high resolution images
allowed us to probe the RC-IR-CO correlations down to linear scales of a few
hundred pc. Results: for the 22 galaxies analysed, the RC-CO correlation on
scales from $\sim10$ kpc down to $\sim100$ pc is nearly linear and has a
scatter of a factor of two, i.e. comparable to that of the global correlations.
There is no evidence for any severe degradation of the scatter below the kpc
scale. This also applies to the six galaxies for which high-resolution mid-IR
data are available. In the case of NGC 5194, we find that the non-thermal radio
spectral index is correlated with the RC/FIR ratio. Conclusions: The scatter of
the point-by-point correlations does not increase significantly with spatial
resolution. We thus conclude that we have not yet probed the physical scales at
which the correlations break down. However, we observe local deviations from
the correlations in regions with a high star formation rate, such as the spiral
arms, where we observe a flat radio spectrum and a low RC/FIR ratio. In the
intra-arm regions and in the peripheral regions of the disk, the RC/FIR is
generally higher and it is characterized by a steepening of the radio spectrum.


title: X-ray temperature spectroscopy of simulated cooling clusters

abstract:
  Results from a large sample of hydrodynamical/N-body simulations of galaxy
clusters in a LCDM cosmology are used to simulate cluster X-ray observations as
expected from Chandra observations. The physical modeling of the gas includes
radiative cooling, star formation, energy feedback and metal enrichment. The
biasing of spectral temperatures with respect to mass-weighted temperatures is
found to be influenced by two independent processes. The first scale dependency
is absent in adiabatic runs and is due to cooling, whose efficiency to
transform cold gas into stars is higher for cool clusters and this in turn
implies a strong dependency of the spectral versus mass-weighted temperature
relation on the cluster mass. The second dependency is due to photon emission
because of cool gas which is accreted during merging events and biases the
spectral fits. These events have been quantified according to the power ratio
method and a robust correlation is found to exist between the spectral bias and
the amount of cluster substructure. The shape of the simulated temperature
profiles is not universal and it is steeper at the cluster center for cool
clusters than for the massive ones. The profiles are in good agreement with
data in the radial range between $\sim 0.1 r_{vir}$ and $\sim 0.4 r_{vir}$; at
small radii ($r< 0.1 r_{vir}$) the cooling runs fail to reproduce the shape of
the observed profiles. The fit is improved if one considers a hierarchical
merging scenario in which cluster cores can accrete cooler gas through merging
with cluster subclumps, though the shape of the temperature profiles is
modified in a significant way only in the regime where the mass of the
substructure is a large fraction of the cluster mass.


title: Intergalactic medium heating by dark matter

abstract:
  We derive the evolution of the energy deposition in the intergalactic medium
(IGM) by dark matter (DM) decays/annihilations for both sterile neutrinos and
light dark matter (LDM) particles. At z > 200 sterile neutrinos transfer a
fraction f_abs~0.5 of their rest mass energy into the IGM; at lower redshifts
this fraction becomes <~ 0.3 depending on the particle mass. The LDM particles
can decay or annihilate. In both cases f_abs~0.4-0.9 at high (> 300) redshift,
dropping to ~0.1 below z=100. These results indicate that the impact of DM
decays/annihilations on the IGM thermal and ionization history is less
important than previously thought. We find that sterile neutrinos (LDM) decays
are able to increase the IGM temperature by z=5 at most up to 4K (100K), about
50-200 times less than predicted by estimates based on the assumption of
complete energy transfer to the gas.


title:
The impact of dark matter decays and annihilations on the formation of
  the first structures

abstract:
  We derive the effects of DM decays and annihilations on structure formation.
We consider moderately massive DM particles (sterile neutrinos and light DM),
as they are expected to give the maximum contribution to heating and
reionization. The energy injection from DM decays and annihilations produces
both an enhancement in the abundance of coolants (H2 and HD) and an increase of
gas temperature. We find that for all the considered DM models the critical
halo mass for collapse, m_crit, is generally higher than in the unperturbed
case. However, the variation of m_crit is small. In the most extreme case, i.e.
considering light DM annihilations (decays) and halos virializing at redshift
z_vir>10 (z_vir~10), m_crit increases by a factor ~4 (~2). In the case of
annihilations the variations of m_crit are also sensitive to the assumed
profile of the DM halo. Furthermore, we note that the fraction of gas which is
retained inside the halo is substantially reduced (to ~40 per cent of the
cosmic value), especially in the smallest halos, as a consequence of the energy
injection by DM decays and annihilations.


title: First astrophysical results from AMBER/VLTI

abstract:
  The AMBER instrument installed at the Very Large Telescope (VLT) combines
three beams from as many telescopes to produce spectrally dispersed fringes
from milli-arcsecond angular scale in the near infrared. Two years after
installation, first scientific observations have been carried out during the
Science Demonstration Time and the Guaranteed Time mostly on bright sources due
to some VLTI limitations. In this paper, we review these first astrophysical
results and we show which types of completely new information is brought by
AMBER. The first astrophysical results have been mainly focusing on stellar
wind structure, kinematics, and its interaction with dust usually concentrated
in a disk. Because AMBER has dramatically increased the number of measures per
baseline, this instrument brings strong constraints on morphology and models
despite a relatively poor (u, v) coverage for each object.


title:
A Quantitative Analysis of the Available Multicolor Photometry for
  Rapidly Pulsating Hot B Subdwarfs

abstract:
  We present a quantitative and homogeneous analysis of the broadband
multicolor photometric data sets gathered so far on rapidly pulsating hot B
subdwarf stars. This concerns seven distinct data sets related to six different
stars. Our analysis is carried out within the theoretical framework developed
by Randall et al., which includes full nonadiabatic effects. The goal of this
analysis is partial mode identification, i.e., the determination of the degree
index l of each of the observed pulsation modes. We assume possible values of l
from 0 to 5 in our calculations. For each target star, we compute a specific
model atmosphere and a specific pulsation model using estimates of the
atmospheric parameters coming from time-averaged optical spectroscopy. For
every assumed value of l, we use a formal chi-squared approach to model the
observed amplitude-wavelength distribution of each mode, and we compute a
quality-of-fit Q probability to quantify the derived fit and to discriminate
objectively between the various solutions. We find that no completely
convincing and unambiguous l identification is possible on the basis of the
available data, although partial mode discrimination has been reached for 25
out of the 41 modes studied. A brief statistical study of these results
suggests that a majority of the modes must have l values of 0, 1, and 2, but
also that modes with l = 4 could very well be present while modes with l = 3
appear to be rarer. This is in line with recent results showing that l = 4
modes in rapidly pulsating B subdwarfs have a higher visibility in the optical
domain than modes with l = 3. Although somewhat disappointing in terms of mode
discrimination, our results still suggest that the full potential of multicolor
photometry for l identification in pulsating subdwarfs is within reach.


title: Very High Energy Gamma-Ray Observations with H.E.S.S

abstract:
  The H.E.S.S. Imaging Atmospheric Cherenkov Telescope Array is currently the
most sensitive instrument for Very High Energy (VHE) gamma-ray observations in
the energy range of about 0.1-10 TeV. During more than two years of operation
with the complete 4-telescope array, many galactic and extragalactic VHE
gamma-ray sources have been discovered. With its superior sensitivity and its
large field-of-view camera, H.E.S.S. is particularly suited for surveys and
detailed studies of extended sources. A selection of recent H.E.S.S. results is
presented in this proceeding.


title:
Statistical analysis of BATSE gamma-ray bursts: Self-similarity and the
  Amati-relation

abstract:
  The statistical properties of a complete, flux limited sample of 197 long
gamma--ray bursts (GRBs) detected by BATSE are studied. In order to bring forth
their main characteristics, care was taken to define a representative set of
ten parameters. A multivariate analysis gives that ~70% of the total variation
in parameter values is driven by only three principal components. The variation
of the temporal parameters is clearly distinct from that of the spectral ones.
A close correlation is found between the half-width of the autocorrelation
function (tau) and the emission time (Tem); most importantly, this correlation
is self-similar in the sense that the mean values and dispersions of both tau
and Tem scale with the duration of the burst (T90). It is shown that the
Amati-relation can be derived from the sample and that the scatter around this
relation is correlated with the value of tau. Hence, tau has a role similar to
that of the break in the afterglow light curve (Tb) in the Ghirlanda-relation.
In the standard GRB-scenario, the close relation between a global parameter
(Tb) and a local one (tau) indicates that some of the jet-properties do not
vary much for different lines of sight. Finally, it is argued that the basic
temporal and spectral properties are associated with individual pulses, while
the overall properties of a burst is determined mainly by the number of pulses.


title: INTEGRAL observations of AGN obscured by the Galactic Plane

abstract:
  In this paper we present INTEGRAL observations of 7 AGNs: two newly
discovered type 1 Seyferts, IGR J18027-1455 and IGR J21247+5058, and five well
known Seyferts, NGC 6814 (type 1.5), Cyg A (Type 2), MCG-05-23-16 (type 2), ESO
103-G035 (type2) and GRS1734-292. For IGR J18027-1455 and IGR J21247+5058 only
INTEGRAL/IBIS data were available, while broadband spectra are presented and
discussed for the remaining 5 sources for which either BeppoSAX or ASCA data
were used in conjunction with INTEGRAL measurements. In the cases of NGC 6814
and GRS 1734-292, data taken in different periods indicate variability in the
flux: in the case of NGC 6814 by a factor of 16 over a period of about 10
years. Although limited in size, our sample can be used to investigate the
parameter space of both the photon index and cut-off energy. The mean photon
index is 1.8, while the cut-off energy ranges from 30-50 keV to greater than
200 keV; in the particular case of MCG-05-23-16, ESO 103-G035 and GRS 1734-292
the cut-off energy is well constrained at or below 100 keV. We have also tested
an enlarged sample, which includes INTEGRAL data of 3 more AGNs, against the
correlation found by a number of authors between the photon index and the
cut-off energy but have found no evidence for a relation between these two
parameters. Our analysis indicates that there is a diversity in cut-off
energies in the primary continuum of Seyfert galaxies.


title: Galactic Nuclei and Jets in Wave Gravity

abstract:
  "Wave gravity" refers to a quantum-mechanical gravity theory introduced in
two previous papers [1,2]. Although based on the optics of de Broglie waves
instead of curved space-time, it agrees with the standard tests of general
relativity. As in that theory, galactic nuclei are dark objects where gravity
prevents the escape of most radiation. In this case, collapse is counteracted
by rising internal pressure and black hole singularities don't occur. Unlike
black holes, these nuclei can have internal magnetic fields, and high-energy
plasma can escape along magnetic field lines closely aligned with the
gravitational field direction. This allows a different model of jets from
active galactic nuclei, where jets can arise without direct fueling by
accretion disks. It also offers a new basis for the tight correlation observed
[13] between the masses of galactic nuclei and their hosts.


title:
The Star Formation History and Evolution of the Circumnuclear Region of
  M100

abstract:
  (Abridged) Star-forming nuclear rings in barred galaxies are common in nearby
spirals, and their detailed study can lead to important insights into the
evolution of galaxies, their bars, and their central regions. We present
integral field spectroscopic observations obtained with SAURON of the bar and
circumnuclear region of the barred spiral galaxy M100, complemented by new {\it
Spitzer Space Telescope} imaging of the region. We use these data to enhance
our understanding of the formation, evolution, and current properties of the
bar and ring. We derive the kinematics of the gas and the stars and quantify
circular and non-circular motions using kinemetry. We analyse this in
conjunction with the optical and infrared morphology, and our previously
published dynamical modelling. By comparing line indices to simple stellar
population models we estimate the ages and metallicities of the stellar
populations present within the region, especially in and around the ring. Our
kinematic and morphological results all confirm the picture in which the
nuclear ring in M100, considered typical, is fed by gas flowing in from the
disc under the action of the bar, is slowed down near a pair of resonances, and
forms significant amounts of massive stars. Detailed stellar population
modelling shows how the underlying bulge and disc were put in place a number of
Gyr ago, and that the nuclear ring has been forming stars since about 500~Myr
ago in a stable succession of bursts. This confirms that nuclear rings of this
kind can form under the influence of a resonant structure set up by a bar, and
proves that they are stable features of a galaxy rather than one-off starburst
events.


title: Infrared observations of V838 Mon

abstract:
  We describe the results of fitting simple spherically symmetric models to the
first overtone CO and AlO A-X (2-0) bands in V838 Mon. We find that the
temperature and column of both CO and AlO systematically decline over the
period 2002 October - 2005 February and that an additional, hotter and denser,
component is present from 2005 January. We also describe the results of an
observation of the star and its light echo at 850micron. We do not detect the
`infrared' echo at these wavelength, and place an upper limit of 3x10^7 cm^-2
on the column of grains.


title:
Diffuse, Non-Thermal X-ray Emission from the Galactic Star Cluster
  Westerlund 1

abstract:
  We present the diffuse X-ray emission identified in Chandra observations of
the young, massive Galactic star cluster Westerlund 1. After removing
point-like X-ray sources down to a completeness limit of 2e31 erg/s, we
identify 3e34 erg/s (2--8 keV) of diffuse emission. The spatial distribution of
the emission can be described as a slightly-elliptical Lorentzian core with a
half-width half-maximum along the major axis of 25+/-1", similar to the
distribution of point sources in the cluster, plus a 5' halo of extended
emission. The spectrum of the diffuse emission is dominated by a hard continuum
component that can be described as a kT>3 keV thermal plasma that has a low
iron abundance (<0.3 solar), or as non-thermal emission that could be stellar
light that is inverse-Compton scattered by MeV electrons. Only 5% of the flux
is produced by a kT=0.7 keV plasma. The low luminosity of the thermal emission
and the lack of a 6.7 keV iron line suggests that <40,000 unresolved stars with
masses between 0.3 and 2 Msun are present in the cluster. Moreover, the flux in
the diffuse emission is a factor of two lower than would be expected from a
supersonically-expanding cluster wind, and there is no evidence for thermal
remnants produced by supernovae. Less than 1e-5 of the mechanical luminosity of
the cluster is dissipated as 2--8 keV X-rays, leaving a large amount of energy
that either is radiated at other wavelengths, is dissipated beyond the bounds
of our image, or escapes into the intergalactic medium.


title: Discovery of a new high redshift QSO at z=5.96 with the Subaru telescope

abstract:
  We report a discovery of a new high redshift quasar at $z=5.96$, observed
with the FOCAS long-slit spectrograph on board the Subaru telescope. The
spectrum shows strong and broad Ly$\alpha$+NV emission lines with a sharp
discontinuity to the blue side. A Ly$\beta$+OVI emission line is also detected,
providing a consistent redshift measurement with the Ly$\alpha$+NV emission.
The QSO has an absolute magnitude of $M_{AB,1450}=-26.9$ ($H_{0}=50$km s$^{-1}$
Mpc$^{-1}$, $q_0=0.5$).
  The spectrum shows significant flux in the region 8000-8300 $\AA$ and thus
does not show a complete Gunn-Peterson trough in the redshift range 5.58 to
5.82, along the line of sight to this $z=5.96$
  QSO. Therefore the Universe was already highly ionized at $z=5.82$


title:
Multiwavelength Monitoring of the Dwarf Seyfert 1 Galaxy NGC 4395. III.
  Optical Variability and X-ray/UV/Optical Correlations

abstract:
  We present optical observations of the low-luminosity Seyfert 1 nucleus of
NGC 4395, as part of a multiwavelength reverberation-mapping program.
Observations were carried out over two nights in 2004 April at Lick, Wise, and
Kitt Peak Observatories. We obtained V-band and B-band photometry, and spectra
over the range 3500-6800 Angstroms. Simultaneous Hubble Space Telescope UV and
Chandra X-ray observations are presented in companion papers. Even though NGC
4395 was in an extremely low state of activity, we detect significant continuum
variability of 2-10%, increasing toward shorter wavelengths. The continuum
light curves, both spectroscopic and photometric, are qualitatively similar to
the simultaneous UV and X-ray light curves. Inter-band cross-correlations
suggest that the optical continuum emission lags behind the UV continuum
emission by 24 +7/-9 min, and that the optical continuum emission lags behind
the X-ray continuum emission by 44 +/- 13 min, consistent with a reprocessing
model for active galactic nucleus emission. There are also hints of Balmer
emission lines lagging behind the optical continuum by an amount slightly
larger than the emission-line lag detected in the UV. These results are all
similar to those of other Seyfert 1 nuclei. The emission-line lag yields a mass
measurement of the central black hole, which although not very significant, is
consistent with the value derived from the simultaneous UV data.


title: Search for Lambda-Doubling Transitions of SiH in Orion KL

abstract:
  A recent submillimeter line survey of Orion KL claimed detection of SiH. This
paper reports on GBT observations of the 5.7 GHz Lambda-doubling transitions of
SiH in Orion. Many recombination lines, including C164-delta, are seen, but SiH
is not detected. The nondetection corresponds to an upper limit of 1.5 x 10^15
cm^-2 (4 sigma) for the beam-averaged column density of SiH. This suggests that
the fractional abundance of SiH in the extended ridge is no more than twice
that in the hot core.


title: Low Mach Number Modeling of Type Ia Supernovae. II. Energy Evolution

abstract:
  The convective period leading up to a Type Ia supernova (SN Ia) explosion is
characterized by very low Mach number flows, requiring hydrodynamical methods
well-suited to long-time integration. We continue the development of the low
Mach number equation set for stellar scale flows by incorporating the effects
of heat release due to external sources. Low Mach number hydrodynamics
equations with a time-dependent background state are derived, and a numerical
method based on the approximate projection formalism is presented. We
demonstrate through validation with a fully compressible hydrodynamics code
that this low Mach number model accurately captures the expansion of the
stellar atmosphere as well as the local dynamics due to external heat sources.
This algorithm provides the basis for an efficient simulation tool for studying
the ignition of SNe Ia.


title: The Planets-Capture Model of V838 Monocerotis

abstract:
  The planets capture model for the eruption of V838 Mon is discussed. We used
three methods to estimate the location where the planets were consumed. There
is a nice consistency for the results of the three different methods, and we
find that the typical stopping / slowing radius for the planets is about 1Ro.
The three peaks in the optical light curve of V838 Mon are either explained by
the swallowing of three planets at different radii or by three steps in the
slowing down process of a single planet. We discuss the other models offered
for the outburst of V838 Mon, and conclude that the binary merger model and the
planet/s scenario seem to be the most promising. These two models have several
similarities, and the main differences are the stellar evolutionary stage, and
the mass of the accreted material. We show that the energy emitted in the V838
Mon event is consistent with the planets scenario. We suggest a few
explanations for the trigger for the outburst and for the double structure of
the optical peaks in the light curve of V838 Mon.


title:
Detection of additional Wolf-Rayet stars in the starburst cluster
  Westerlund 1 with SOAR

abstract:
  We report the detection of 3 additional Wolf-Rayet stars in the young cluster
Westerlund 1. They were selected as emission-line star candidates based on 1
micron narrow-band imaging of the cluster carried out at OPD/LNA (Brazil), and
then confirmed as Wolf-Rayet stars by K-band spectroscopy performed at the 4.1
m SOAR telescope (Chile). Together with previous works, this increases the
population of Wolf-Rayet stars detected in the cluster to 22 members. Moreover,
it is presented for the first time a K-band spectrum of the luminous blue
variable W243, which apparently implies in a higher temperature than that
derived from optical spectra taken in 2003. The WC9 star WR-F was also
observed, showing clear evidence of dust emission in the K-band.


title:
Nearby Supernova Factory Observations of SN 2005gj: Another Type Ia
  Supernova in a Massive Circumstellar Envelope

abstract:
  We report Nearby Supernova Factory observations of SN 2005gj, the second
confirmed case of a "hybrid" Type Ia/IIn supernova. Our early-phase photometry
of SN 2005gj shows that the interaction is much stronger than for the
prototype, SN 2002ic. Our first spectrum shows a hot continuum with broad and
narrow H-alpha emission. Later spectra, spanning over 4 months from outburst,
show clear Type Ia features combined with broad and narrow H-gamma, H-beta,
H-alpha and HeI 5876,7065 in emission. At higher resolution, P Cygni profiles
are apparent. Surprisingly, we also observe an inverted P Cygni profile for
[OIII] 5007. We find that the lightcurve and measured velocity of the unshocked
circumstellar material imply mass loss as recently as 8 years ago. The early
lightcurve is well-described by a flat radial density profile for the
circumstellar material. However, our decomposition of the spectra into Type Ia
and shock emission components allows for little obscuration of the supernova,
suggesting an aspherical or clumpy distribution for the circumstellar material.
We suggest that the emission line velocity profiles arise from electron
scattering rather than the kinematics of the shock. This is supported by the
inferred high densities, and the lack of evidence for evolution in the line
widths. Ground- and space-based photometry, and Keck spectroscopy, of the host
galaxy are used to ascertain that the host galaxy has low metallicity Z/Zsun <
0.3; (95% confidence) and that this galaxy is undergoing a significant star
formation event that began roughly 200+/-70 Myr ago. We discuss the
implications of these observations for progenitor models and cosmology using
Type Ia supernovae.


title:
On the Perils of Curve-of-Growth Analysis: Systematic Abundance
  Underestimates for the Gas in Gamma-Ray Burst Host Galaxies

abstract:
  We examine the practice of deriving interstellar medium (ISM) abundances from
low-resolution spectroscopy of GRB afterglows. We argue that the multi-ion
single-component curve-of-growth analysis technique systematically
underestimates the column densities of the metal-line profiles commonly
observed for GRB. This systematic underestimate is accentuated by the fact that
many GRB line-profiles (e.g. GRB 050730, GRB 050820, GRB 051111) are comprised
of `clouds' with a bi-modal distribution of column density. Such line-profiles
may be characteristic of a sightline which penetrates both a high density
star-forming region and more distant, ambient ISM material. Our analysis
suggests that the majority of abundances reported in the literature are
systematically underestimates and that the reported errors are frequently
over-optimistic. Further, we demonstrate that one cannot even report precise
relative abundances with confidence. The implications are profound for our
current understanding on the metallicity, dust-to-gas ratio, and chemical
abundances of the ISM in GRB host galaxies. For example, we argue that all but
a few sightlines allow for the gas to have at least solar metallicity. Finally,
we suggests new approaches for constraining the abundances.


title: The Recurrent Eclipse of an Unusual Pre--Main-Sequence Star in IC 348

abstract:
  The recurrence of a previously documented eclipse of a solar-like
pre--main-sequence star in the young cluster IC 348 has been observed. The
recurrence interval is 4.7 $\pm 0.1$ yr and portions of 4 cycles have now been
seen. The duration of each eclipse is at least 3.5 years, or $\sim 75$% of a
cycle, verifying that this is not an eclipse by a stellar companion. The light
curve is generally symmetric and approximately flat-bottomed. Brightness at
maximum and minimum have been rather stable over the years but the light curve
is not perfectly repetitive or smooth and small variations exist at all phases.
We confirm that the star is redder when fainter. Models are discussed and it is
proposed that this could be a system similar to KH 15D in NGC 2264.
Specifically, it may be an eccentric binary in which a portion of the orbit of
one member is currently occulted during some binary phases by a circumbinary
disk. The star deserves sustained observational attention for what it may
reveal about the circumstellar environment of low-mass stars of planet-forming
age.


title:
Integral Field Spectroscopy of the Extended Emission-Line Region of 3C
  249.1

abstract:
  We present Gemini Multiobject Spectrograph integral field spectroscopy of the
extended emission-line region associated with quasar 3C 249.1. The kinematics
of the ionized gas measured from the [O III] $\lambda$5007 line is rather
complex and cannot be explained globally by a simple dynamical model, but some
clouds can be modeled individually as having locally linear velocity gradients.
The temperatures of the ionized gas appear uniform (varying from ~12000 to
15000 K), while the densities vary from a few tens to a few hundreds cm^{-3}.
The emission mechanism of all of the emission clouds, as indicated by the
line-ratio diagnostics, is consistent both with "shock + precursor" and pure
photoionization models. The total mass of the ionized gas is on the order of
10^9 M_Sun. We estimate the bulk kinetic energy and momentum of the extended
emission-line region of 2.5*10^{57} ergs and 10^{50} dyne s, and a dynamical
timescale of ~10 Myr. By comparing the injection rates of kinetic energy and
momentum of different galactic wind models with the observation, we argue that
the emission-line clouds are most likely a direct result from the feedback of
the quasar. We also discuss the nature of the extended X-ray emission
surrounding the quasar.


title:
The new HiVIS spectropolarimeter and spectropolarimetric calibration of
  the AEOS telescope

abstract:
  We designed, built, and calibrated a new spectropolarimeter for the HiVIS
spectrograph (R 12000-49000) on the AEOS telescope. We also did a polarization
calibration of the telescope and instrument. We will introduce the design and
use of the spectropolarimeter as well as a new data reduction package we have
developed, then discuss the polarization calibration of the spectropolarimeter
and the AEOS telescope. We used observations of unpolarized standard stars at
many pointings to measure the telescope induced polarization and compare it
with a Zemax model. The telescope induces polarization of 1-6% with a strong
variation with wavelength and pointing, consistent with the altitude and
azimuth variation expected. We then used scattered sunlight as a linearly
polarized source to measure the telescopes spectropolarimetric response to
linearly polarized light. We then made an all-sky map of the telescope's
polarization response to calibrate future spectropolarimetry.


title:
Standing Accretion Shocks in the Supernova Core: Effects of Convection
  and Realistic EOS

abstract:
  We investigated the structure of the spherically symmetric accretion flows
through the standing shock wave onto the proto-neutron star in the post-bounce
phase of the collapse-driven supernova. We assume that the accretion flow is in
a steady state controlled by the neutrino luminosity and mass accretion rate
that are kept constant. We obtain solutions of the steady Euler equations for a
wide range of neutrino luminosity and mass accretion rate. We employ a
realistic EOS and neutrino-heating rates. More importantly, we take into
account the effect of convection phenomenologically. For each mass accretion
rate, we find the critical neutrino luminosity, above which there exists no
steady solution. These critical points are supposed to mark the onset of the
shock revival. As the neutrino luminosity increases for a given mass accretion
rate, there appears a convectively unstable region at some point before the
critical value is reached. We introduce a phenomenological energy flux by
convection so that the negative entropy gradient should be canceled out. We
find that the convection lowers the critical neutrino luminosity substantially.
We also consider the effect of the self-gravity. It is found that the
self-gravity is important only when the neutrino luminosity is high. The
critical luminosity, however, is little affected if the energy transport by
convection is taken into account.


title: Transients from Initial Conditions in Cosmological Simulations

abstract:
  We study the impact of setting initial conditions in numerical simulations
using the standard procedure based on the Zel'dovich approximation (ZA). As it
is well known from perturbation theory, ZA initial conditions have incorrect
second and higher-order growth and therefore excite long-lived transients in
the evolution of the statistical properties of density and velocity fields. We
also study the improvement brought by using more accurate initial conditions
based on second-order Lagrangian perturbation theory (2LPT). We show that 2LPT
initial conditions reduce transients significantly and thus are much more
appropriate for numerical simulations devoted to precision cosmology. Using
controlled numerical experiments with ZA and 2LPT initial conditions we show
that simulations started at redshift z_i=49 using the ZA underestimate the
power spectrum in the nonlinear regime by about 2,4,8 % at z=0,1,3
respectively, whereas the mass function of dark matter halos is underestimated
by 5% at m=10^15 M_sun/h (z=0) and 10% at m=2x10^14M_sun/h (z=1). The
clustering of halos is also affected to the few percent level at z=0. These
systematics effects are typically larger than statistical uncertainties in
recent mass function and power spectrum fitting formulae extracted from
numerical simulations. At large scales, the measured transients in higher-order
correlations can be understood from first principle calculations based on
perturbation theory.


title: Strong lensing probability for testing TeVeS theory

abstract:
  We calculate the strong lensing probability as a function of the
image-separation $\Delta\theta$ in TeVeS (tensor-vector-scalar) cosmology,
which is a relativistic version of MOND (MOdified Newtonian Dynamics). The
lens, often an elliptical galaxy, is modeled by the Hernquist profile. We
assume a flat cosmology with $\Omega_b=1-\Omega_\Lambda=0.04$ and the simplest
interpolating function $\mu(x)={\rm min}(1,x)$. For comparison, we recalculated
the probabilities for lenses by Singular Isothermal Sphere (SIS) galaxy halos
in LCDM with Schechter-fit velocity function. The amplification bias is
calculated based on the magnification of the second bright image rather than
the total of the two brighter images. Our calculations show that the Hernquist
model predicts insufficient but acceptable probabilities in flat TeVeS
cosmology compared with the results of the well defined combined sample of
Cosmic Lens All-Sky Survey (CLASS) and Jodrell Bank/Very Large Array
Astrometric Survey (JVAS); at the same time, it predicts higher probabilities
than SIS model in LCDM at small image separations.


title: Simulation for KM3NeT using ANTARES-Software

abstract:
  The KM3NeT project is a common European effort for the design of a km3-scale
deep-sea neutrino telescope in the Mediterranean. For the upcoming Design Study
simulations have been done using modified ANTARES software. Several concepts
and ideas have been tested for their merits and feasibility.


title: On the Nature of Part Time Radio Pulsars

abstract:
  The recent discovery of rotating radio transients and the quasi-periodicity
of pulsar activity in the radio pulsar PSR B1931$+$24 has challenged the
conventional theory of radio pulsar emission. Here we suggest that these
phenomena could be due to the interaction between the neutron star
magnetosphere and the surrounding debris disk. The pattern of pulsar emission
depends on whether the disk can penetrate the light cylinder and efficiently
quench the processes of particle production and acceleration inside the
magnetospheric gap. A precessing disk may naturally account for the
switch-on/off behavior in PSR B1931$+$24.


title:
On the dependence of the spectral parameters on the observational
  conditions in homogeneous time dependent models of the TeV blazars

abstract:
  Most of current models of TeV blazars emission assume a Synchrotron
Self-Compton mechanism where relativistic particles emit both synchrotron
radiation and Inverse Compton photons. For sake of simplicity, these models
usually consider only steady state emission. The spectral features are thus
only related to the shape of the particle distribution, and do not depend on
the timing of observations. In this letter, we study the effect of, firstly,
the lag between the beginning of the injection of the fresh particles and the
trigger of the observation, and secondly, of a finite injection duration. We
illustrate these effects considering an analytical time-dependent model of the
synchrotron emission by a monoenergetic distribution of leptons. We point out
that the spectral shape can be in fact very dependent on observational
conditions if the particle injection term is time-dependent, particularly
taking into account the effect of the time averaging procedure on the final
shape of the SED. Consequences on the acceleration process are also discussed.


title: Linear Stability of Ring Systems

abstract:
  We give a self-contained modern linear stability analysis of a system of n
equal mass bodies in circular orbit about a single more massive body. Starting
with the mathematical description of the dynamics of the system, we form the
linear approximation, compute all of the eigenvalues of the linear stability
matrix, and finally derive inequalities that guarantee that none of these
eigenvalues have positive real part. In the end, we rederive the result that
J.C. Maxwell found for large n in his seminal paper on the nature and stability
of Saturn's rings, which was published 150 years ago. In addition, we identify
the exact matrix that defines the linearized system even when n is not large.
This matrix is then investigated numerically (by computer) to find stability
inequalities. Furthermore, using properties of circulant matrices, the
eigenvalues of the large 4nx4n matrix can be computed by solving n quartic
equations, which further facilitates the investigation of stability. Finally,
we have implemented an n-body simulator and we verify that the threshold mass
ratios that we derived mathematically or numerically do indeed identify the
threshold between stability and instability. Throughout the paper we consider
only the planar n-body problem so that the analysis can be carried out purely
in complex notation, which makes the equations and derivations more compact,
more elegant and therefore, we hope, more transparent. The result is a fresh
analysis that shows that these systems are always unstable for 2<=n<=6 and for
n > 6 they are stable provided that the central mass is massive enough. We give
an explicit formula for this mass-ratio threshold.


title: The CMB polarization: status and prospects

abstract:
  The study of cosmic microwave background (CMB) polarization is still in a
pioneering stage, but promises to bring a huge advancement in cosmology in the
near future, just as high-accuracy observations of the anisotropies in the
total intensity of the CMB revolutionized our understanding of the universe in
the past few years. In this contribution, we outline the scientific case for
observing CMB polarization, and review the current observational status and
future experimental prospects in the field.


title: Cosmological quests in the CMB sky

abstract:
  Observational Cosmology has indeed made very rapid progress in recent years.
The ability to quantify the universe has largely improved due to observational
constraints coming from structure formation Measurements of CMB anisotropy and,
more recently, polarization have played a very important role. Besides precise
determination of various parameters of the `standard' cosmological model,
observations have also established some important basic tenets that underlie
models of cosmology and structure formation in the universe -- `acausally'
correlated initial perturbations in a flat, statistically isotropic universe,
adiabatic nature of primordial density perturbations. These are consistent with
the expectation of the paradigm of inflation and the generic prediction of the
simplest realization of inflationary scenario in the early universe. Further,
gravitational instability is the established mechanism for structure formation
from these initial perturbations. In the next decade, future experiments
promise to strengthen these deductions and uncover the remaining crucial
signature of inflation -- the primordial gravitational wave background.


title:
A new method for the spectroscopic identification of stellar non-radial
  pulsation modes. I. The method and numerical tests

abstract:
  We present the Fourier parameter fit method, a new method for
spectroscopically identifying stellar radial and non-radial pulsation modes
based on the high-resolution time-series spectroscopy of absorption-line
profiles. In contrast to previous methods this one permits a quantification of
the statistical significance of the computed solutions. The application of
genetic algorithms in seeking solutions makes it possible to search through a
large parameter space. The mode identification is carried out by minimizing
chi-square, using the observed amplitude and phase across the line profile and
their modeled counterparts. Computations of the theoretical line profiles are
based on a stellar displacement field, which is described as superposition of
spherical harmonics and that includes the first order effects of the Coriolis
force. We made numerical tests of the method on a grid of different mono- and
multi-mode models for 0 <= l <= 4 in order to explore its capabilities and
limitations. Our results show that whereas the azimuthal order m can be
unambiguously identified for low-order modes, the error of l is in the range of
pm 1. The value of m can be determined with higher precision than with other
spectroscopic mode identification methods. Improved values for the inclination
can be obtained from the analysis of non-axisymmetric pulsation modes. The new
method is ideally suited to intermediatley rotating Delta Scuti and Beta Cephei
stars.


title: Elevation angle dependence of the SMA antenna focus position

abstract:
  We report the measurement results and compensation of the antenna elevation
angle dependences of the Sub-millimeter Array (SMA) antenna characteristics.
Without optimizing the subreflector (focus) positions as a function of the
antenna elevation angle, antenna beam patterns show lopsided sidelobes, and
antenna efficiencies show degradations. The sidelobe level increases and the
antenna efficiencies decrease about 1% and a few %, respectively, for every 10
degrees change in the elevation angle at the measured frequency of 237 GHz. We
therefore obtained the optimized subreflector positions for X (azimuth), Y
(elevation), and Z (radio optics) focus axes at various elevation angles for
all the eight SMA antennas. The X axis position does not depend on the
elevation angle. The Y and Z axes positions depend on the elevation angles, and
are well fitted with a simple function for each axis with including a gravity
term (cosine and sine of elevation, respectively). In the optimized
subreflector positions, the antenna beam patterns show low level symmetric
sidelobe of at most a few %, and the antenna efficiencies stay constant at any
antenna elevation angles. Using one set of fitted functions for all antennas,
the SMA is now operating with real-time focusing, and showing constant antenna
characteristics at any given elevation angle.


title:
A new method for the spectroscopic identification of stellar non-radial
  pulsation modes. II. Mode identification of the Delta Scuti star FG Virginis

abstract:
  We present a mode identification based on new high-resolution time-series
spectra of the non-radially pulsating Delta Scuti star FG~Vir (HD 106384, V =
6.57, A5V). From 2002 February to June a global Delta Scuti Network (DSN)
campaign, utilizing high-resolution spectroscopy and simultaneous photometry
has been conducted for FG~Vir in order to provide a theoretical pulsation
model. In this campaign we have acquired 969 Echelle spectra covering 147 hours
at six observatories. The mode identification was carried out by analyzing line
profile variations by means of the Fourier parameter fit method, where the
observational Fourier parameters across the line are fitted with theoretical
values. This method is especially well suited for determining the azimuthal
order m of non-radial pulsation modes and thus complementary with the method of
Daszynska-Daszkiewicz (2002) which does best at identifying the degree l. 15
frequencies between 9.2 and 33.5 c/d were detected spectroscopically. We
determined the azimuthal order m of 12 modes and constrained their harmonic
degree l. Only modes of low degree (l <= 4) were detected, most of them having
axisymmetric character mainly due to the relatively low projected rotational
velocity of FG Vir. The detected non-axisymmetric modes have azimuthal orders
between -2 and 1. We derived an inclination of 19 degrees, which implies an
equatorial rotational rate of 66 km/s.


title:
The Minimum Description Length Principle and Model Selection in
  Spectropolarimetry

abstract:
  It is shown that the two-part Minimum Description Length Principle can be
used to discriminate among different models that can explain a given observed
dataset. The description length is chosen to be the sum of the lengths of the
message needed to encode the model plus the message needed to encode the data
when the model is applied to the dataset. It is verified that the proposed
principle can efficiently distinguish the model that correctly fits the
observations while avoiding over-fitting. The capabilities of this criterion
are shown in two simple problems for the analysis of observed
spectropolarimetric signals. The first is the de-noising of observations with
the aid of the PCA technique. The second is the selection of the optimal number
of parameters in LTE inversions. We propose this criterion as a quantitative
approach for distinguising the most plausible model among a set of proposed
models. This quantity is very easy to implement as an additional output on the
existing inversion codes.


title:
Confirmation of the Planet Hypothesis for the Long-period Radial
  Velocity Variations of Beta Geminorum

abstract:
  We present precise stellar radial velocity measurements for the K giant star
Beta Gem spanning over 25 years. These data show that the long period low
amplitude radial velocity variations found by Hatzes & Cochran (1993) are
long-lived and coherent. An examination of the Ca II K emission, spectral line
shapes from high resolution data (R = 210,000), and Hipparcos photometry show
no significant variations of these quantities with the RV period. These data
confirm the planetary companion hypothesis suggested by Hatzes & Cochran
(1993). An orbital solution assuming a stellar mass of 1.7 M_sun yields a
period, P = 589.6 days, a minimum mass of 2.3 M_Jupiter, and a semi-major axis,
and a = 1.6 AU. The orbit is nearly circular (e = 0.02). Beta Gem is the
seventh intermediate mass star shown to host a sub-stellar companion and
suggests that planet-formation around stars much more massive than the sun may
common.


title: Radial Velocity Studies of Southern Close Binary Stars.I

abstract:
  Radial-velocity measurements and sine-curve fits to the orbital velocity
variations are presented for nine contact binaries, V1464 Aql, V759 Cen, DE
Oct, MW Pav, BQ Phe, EL Aqr, SX Crv, VZ Lib, GR Vir; for the first five among
these, our observations are the first available radial velocity data. Among
three remaining radial velocity variables, CE Hyi is a known visual binary,
while CL Cet and V1084 Sco are suspected to be multiple systems where the
contact binary is spectrally dominated by its companion (which itself is a
binary in V1084 Sco). Five additional variables, V872 Ara, BD Cap, HIP 69300,
BX Ind, V388 Pav, are of unknown type, but most are pulsating stars; we give
their mean radial velocities and Vsini.


title: The hierarchical formation of the brightest cluster galaxies

abstract:
  We use semi-analytic techniques to study the formation and evolution of
brightest cluster galaxies (BCGs). We show the extreme hierarchical nature of
these objects and discuss the limits of simple ways to capture their evolution.
In a model where cooling flows are suppressed at late times by AGN activity,
the stars of BCGs are formed very early (50 per cent at z~5, 80 per cent at
z~3) and in many small galaxies. The high star formation rates in these high-z
progenitors are fuelled by rapid cooling, not by merger-triggered starbursts.
We find that model BCGs assemble surprisingly late: half their final mass is
typically locked-up in a single galaxy after z~0.5. Because most of the
galaxies accreted onto BCGs have little gas content and red colours, late
mergers do not change the apparent age of BCGs. It is this accumulation of a
large number of old stellar populations -- driven mainly by the merging history
of the dark matter halo itself -- that yields the observed homogeneity of BCG
properties. In the second part of the paper, we discuss the evolution of BCGs
to high redshifts, from both observational and theoretical viewpoints. We show
that our model BCGs are in qualitative agreement with high-z observations. We
discuss the hierarchical link between high-z BCGs and their local
counter-parts. We show that high-z BCGs belong to the same population as the
massive end of local BCG progenitors, although they are not in general the same
galaxies. Similarly, high-z BCGs end-up as massive galaxies in the local
Universe, although only a fraction of them are actually BCGs of massive
clusters.


title: Interacting models of soft coincidence

abstract:
  The coincidence problem of late cosmic acceleration is a serious riddle in
connection with our understanding of the evolution of the Universe. In this
paper we show that an interaction between the dark energy component (either
phantom or quintessence) and dark matter can alleviate it. In this scenario the
baryon component is independently conserved. This generalizes a previous study
[S. del Campo, R. Herrera, and D. Pavon, Phys. Rev. D 71, 123529 (2005)] in
which neither baryons nor phantom energy were considered.


title:
The Different Environmental Dependencies of Star-formation for Giant and
  Dwarf Galaxies

abstract:
  We examine the origins of the bimodality observed in the global properties of
galaxies around a stellar mass of 3x10^10 M_sun by comparing the environmental
dependencies of star-formation for the giant and dwarf galaxy populations. The
Sloan Digital Sky Survey DR4 spectroscopic dataset is used to produce a sample
of galaxies in the vicinity of the supercluster centered on the cluster A2199
at z=0.03 that is ~90% complete to a magnitude limit of M*+3.3. From these we
measure global trends with environment for both giant (M_r<-20 mag) and dwarf
(-19<M_r<-17.8 mag) subsamples using the luminosity-weighted mean stellar age
and H_alpha emission as independent measures of star-formation history. The
fraction of giant galaxies classed as old (t>7 Gyr) or passive (EW[H_alpha]<4
A) falls gradually from ~80% in the cluster cores to ~40% in field regions
beyond 3-4 R_virial, as found in previous studies. In contrast, we find that
the dwarf galaxy population shows a sharp transition at ~1 R_virial, from being
predominantly old/passive within the cluster, to outside where virtually all
galaxies are forming stars and old/passive galaxies are only found as
satellites to more massive galaxies. These results imply fundamental
differences in the evolution of giant and dwarf galaxies: whereas the
star-formation histories of giant galaxies are determined primarily by their
merger history, star-formation in dwarf galaxies is much more resilient to the
effects of major mergers. Instead dwarf galaxies become passive only once they
become satellites within a more massive halo, by losing their halo gas
reservoir to the host halo, or through other environment-related processes such
as galaxy harassment and/or ram-pressure stripping.


title: Meteorologic parameters analysis above Dome C made with ECMWF data

abstract:
  In this paper we present the characterization of all the principal
meteorological parameters (wind speed and direction, pressure, absolute and
potential temperature) extended over 25 km from the ground and over two years
(2003 and 2004) above the Antarctic site of Dome C. The data set is composed by
'analyses' provided by the General Circulation Model (GCM) of the European
Center for Medium Weather Forecasts (ECMWF) and they are part of the catalog
MARS. A monthly and seasonal (summer and winter time) statistical analysis of
the results is presented. The Richardson number is calculated for each month of
the year over 25 km to study the stability/instability of the atmosphere. This
permits us to trace a map indicating where and when the optical turbulence has
the highest probability to be triggered on the whole troposphere, tropopause
and stratosphere. We finally try to predict the best expected isoplanatic angle
and wavefront coherence time employing the Richardson number maps, the wind
speed profiles and simple analytical models of CN2 vertical profiles.


title: The conversion of Neutron star to Strange star : A two step process

abstract:
  The conversion of neutron matter to strange matter in a neutron star have
been studied as a two step process. In the first step, the nuclear matter gets
converted to two flavour quark matter. The conversion of two flavour to three
flavour strange matter takes place in the second step. The first process is
analysed with the help of equations of state and hydrodynamical equations,
whereas, in the second process, non-leptonic weak interaction plays the main
role. Velocities and the time of travel through the star of these two
conversion fronts have been analysed and compared.


title: Quark matter in compact stars?

abstract:
  Ozel, in a recent reanalysis of EXO 0748-676 observational data
(astro-ph/0605106), concluded that quark matter probably does not exist in the
center of compact stars. We show that the data is actually consistent with the
presence of quark matter in compact stars.


title:
The Role of Evolutionary Age and Metallicity in the Formation of
  Classical Be Circumstellar Disks I. New Candidate Be Stars in the LMC, SMC,
  and Milky Way

abstract:
  We present B, V, R, and H alpha photometry of 8 clusters in the Small
Magellanic Cloud, 5 in the Large Magellanic Cloud, and 3 Galactic clusters, and
use 2 color diagrams (2-CDs) to identify candidate Be star populations in these
clusters. We find evidence that the Be phenomenon is enhanced in low
metallicity environments, based on the observed fractional early-type candidate
Be star content of clusters of age 10-25 Myr. Numerous candidate Be stars of
spectral types B0 to B5 were identified in clusters of age 5-8 Myr, challenging
the suggestion of Fabregat & Torrejon (2000) that classical Be stars should
only be found in clusters at least 10 Myr old. These results suggest that a
significant number of B-type stars must emerge onto the zero-age-main-sequence
as rapid rotators. We also detect an enhancement in the fractional content of
early-type candidate Be stars in clusters of age 10-25 Myr, suggesting that the
Be phenomenon does become more prevalent with evolutionary age. We briefly
discuss the mechanisms which might contribute to such an evolutionary effect. A
discussion of the limitations of utilizing the 2-CD technique to investigate
the role evolutionary age and/or metallicity play in the development of the Be
phenomenon is offered, and we provide evidence that other B-type objects of
very different nature, such as candidate Herbig Ae/Be stars may contaminate the
claimed detections of ``Be stars'' via 2-CDs.


title: The slope of the GRB Variability/Peak Luminosity Correlation

abstract:
  From a sample of 32 GRBs with known redshift (Guidorzi et al. 2005) and then
a sample of 551 BATSE GRBs with derived pseudo-redshift (Guidorzi 2005), the
time variability/peak luminosity correlation (V vs. L) found by Reichart et al.
(2001) was tested. For both samples the correlation is still found but less
relevant due to a much higher spread of the data. Assuming a straight line in
the logL-logV plane (logL = m logV + b), as done by Reichart et al., the slope
was found lower than that derived by Reichart et al.: m = 1.3_{-0.4}^{+0.8}
(Guidorzi et al. 2005), m = 0.85 +- 0.02 (Guidorzi 2005), to be compared with m
= 3.3^{+1.1}_{-0.9} (Reichart et al. 2001). Reichart & Nysewander (2005)
attribute the different slope to the fact we do not take into account in the
fit the variance of the sample, and demonstrate that, using the method by
Reichart (2001), the data set of Guidorzi et al. (2005) in logL-logV plane is
still well described with slope m = 3.4^{+0.9}_{-0.6}. Here we compare the
results of two methods accounting for the variance of the sample, that
implemented by Reichart (2001) and that by D'Agostini (2005). We demonstrate
that the method by Reichart (2001) provides an inconsistent estimate of the
slope when the sample variance is comparable with the interval of values
covered by the variability. We also show that, using the D'Agostini method, the
slope is consistent with that derived by us earlier and inconsistent with that
derived by Reichart & Nysewander (2005). Finally we discuss the implications on
the interpretations and show that our results are in agreement with the peak
energy/variability correlation found by Lloyd-Ronning & Ramirez-Ruiz (2002) and
the peak energy/peak luminosity correlation (Yonetoku et al. 2004; Ghirlanda et
al. 2005) [abridged].


title:
Lyman Break Galaxies Under a Microscope: The Small Scale Dynamics and
  Mass of an Arc in the Cluster 1E0657-56

abstract:
  Using the near-infrared integral-field spectrograph SPIFFI on the VLT, we
have studied the spatially-resolved dynamics in the z=3.2 strongly lensed
galaxy 1E0657-56 ``arc+core''. The lensing configuration suggests that the high
surface brightness ``core'' is the M=20 magnified central 1 kpc of the galaxy
(seen at a spatial resolution of about 200 pc in the source plane), whereas the
fainter ``arc'' is a more strongly magnified peripheral region of the same
galaxy at about a half-light radius, which otherwise appears to be a typical
z=3 Lyman break galaxy.
  The overall shape of the position-velocity diagram resembles the ``rotation
curves'' of the inner few kpcs of nearby L* spiral galaxies. The projected
velocities rise rapidly to 75 km/s within the core. This implies a dynamical
mass of M_dyn = 10^9.3 M_sun within the central kpc, and suggests that in this
system the equivalent of the mass of a present-day L* bulge at the same radius
was already in place by z>=3. Approximating the circular velocity of the halo
by the measured asymptotic velocity of the rotation curve, we estimate a dark
matter halo mass of M_halo = 10^11.7 +/- 0.3, in good agreement with
large-scale clustering studies of Lyman break galaxies. The baryonic collapse
fraction is low compared to actively star-forming ``BX'' and low-redshift
galaxies around z=2, perhaps implying comparatively less gas infall to small
radii or efficient feedback. Even more speculatively, the high central mass
density might indicate highly dissipative gas collapse in very early stages of
galaxy evolution, in approximate agreement with what is expected for
``inside-out'' galaxy formation models.


title:
Contour binning: a new technique for spatially-resolved X-ray
  spectroscopy applied to Cassiopeia A

abstract:
  We present a new technique for choosing spatial regions for X-ray
spectroscopy, called "contour binning". The method chooses regions by following
contours on a smoothed image of the object. In addition we re-explore a simple
method for adaptively smoothing X-ray images according to the local count rate,
we term "accumulative smoothing", which is a generalisation of the method used
by FADAPT. The algorithms are tested by applying them to a simulated cluster
data set. We illustrate the techniques by using them on a 50 ks Chandra
observation of the Cassiopeia A supernova remnant. Generated maps of the object
showing abundances in eight different elements, absorbing column density,
temperature, ionisation timescale and velocity are presented. Tests show that
contour binning reproduces surface brightness considerably better than other
methods. It is particularly suited to objects with detailed spatial structure
such as supernova remnants and the cores of galaxy clusters, producing
aesthetically pleasing results.


title: New "Bigs" in cosmology

abstract:
  This paper contains a detailed discussion on new cosmic solutions describing
the early and late evolution of a universe that is filled with a kind of dark
energy that may or may not satisfy the energy conditions. The main distinctive
property of the resulting space-times is that they make to appear twice the
single singular events predicted by the corresponding quintessential (phantom)
models in a manner which can be made symmetric with respect to the origin of
cosmic time. Thus, big bang and big rip singularity are shown to take place
twice, one on the positive branch of time and the other on the negative one. We
have also considered dark energy and phantom energy accretion onto black holes
and wormholes in the context of these new cosmic solutions. It is seen that the
space-times of these holes would then undergo swelling processes leading to big
trip and big hole events taking place on distinct epochs along the evolution of
the universe. In this way, the possibility is considered that the past and
future be connected in a non-paradoxical manner in the universes described by
means of the new symmetric solutions.


title:
Extreme gas kinematics in the z=2.2 powerful radio galaxy MRC1138-262:
  Evidence for efficient AGN feedback in the early Universe?

abstract:
  To explain the properties of the most massive low-redshift galaxies and the
shape of their mass function, recent models of galaxy evolution include strong
AGN feedback to complement starburst-driven feedback in massive galaxies. Using
the near-infrared integral-field spectrograph SPIFFI on the VLT, we searched
for direct evidence for such a feedback in the optical emission line gas around
the z=2.16 powerful radio galaxy MRC1138-262, likely a massive galaxy in
formation. The kpc-scale kinematics, with FWHMs and relative velocities <= 2400
km/s and nearly spherical spatial distribution, do not resemble large-scale
gravitational motion or starburst-driven winds. Order-of-magnitude timescale
and energy arguments favor the AGN as the only plausible candidate to
accelerate the gas, with a total energy injection of a few x 10^60 ergs or
more, necessary to power the outflow, and relatively efficient coupling between
radio jet and ISM. Observed outflow properties are in gross agreement with the
models, and suggest that AGN winds might have a similar, or perhaps larger,
cosmological significance than starburst-driven winds, if MRC1138-262 is indeed
archetypal. Moreover, the outflow has the potential to remove significant gas
fractions (<= 50%) from a >L* galaxy within a few 10 to 100 Myrs, fast enough
to preserve the observed [alpha/Fe] overabundance in massive galaxies at low
redshift. Using simple arguments, it appears that feedback like that observed
in MRC1138-262 may have sufficient energy to inhibit material from infalling
into the dark matter halo and thus regulate galaxy growth as required in some
recent models of hierarchical structure formation.


title:
The Tully-Fisher relation and its evolution with redshift in
  cosmological simulations of disc galaxy formation

abstract:
  We present predictions on the evolution of the Tully-Fisher (TF) relation
with redshift, based on cosmological N-body/hydrodynamical simulations of disc
galaxy formation and evolution. The simulations invoke star formation and
stellar feedback, chemical evolution with non-instantaneous recycling,
metallicity dependent radiative cooling and effects of a meta-galactic UV
field, including simplified radiative transfer.
  At z=0, the simulated and empirical TF relations are offset by about 0.4
magnitudes (1 sigma) in the B and I bands. The origin of these offsets is
somewhat unclear, but it may not necessarily be a problem of the simulations
only.
  As to evolution, we find a brightening of the TF relation between z=0 and z=1
of about 0.85 mag in rest-frame B band, with a non-evolving slope. The
brightening we predict is intermediate between the (still quite discrepant)
observational estimates.
  This evolution is primarily a luminosity effect, while the stellar mass TF
relation shows negligible evolution. The individual galaxies do gain stellar
mass between z=1 and z=0, by a 50-100%; but they also correspondingly increase
their characteristic circular speed. As a consequence, individually they mainly
evolve ALONG the stellar mass TF relation, while the relation as such does not
show any significant evolution.


title:
Spitzer/MIPS Imaging of NGC 650: Probing the History of Mass Loss on the
  Asymptotic Giant Branch

abstract:
  We present the far-infrared (IR) maps of a bipolar planetary nebula (PN), NGC
650, at 24, 70, and 160 micron taken with the Multiband Imaging Photometer for
Spitzer (MIPS) on-board the Spitzer Space Telescope. While the two-peak
emission structure seen in all MIPS bands suggests the presence of a near
edge-on dusty torus, the distinct emission structure between the 24 micron map
and the 70/160 micron maps indicates the presence of two distinct emission
components in the central torus. Based on the spatial correlation of these two
far-IR emission components with respect to various optical line emission, we
conclude that the 24 micron emission is largely due to the [O IV] line at 25.9
micron arising from highly ionized regions behind the ionization front, whereas
the 70 and 160 micron emission is due to dust continuum arising from
low-temperature dust in the remnant asymptotic giant branch (AGB) wind shell.
The far-IR nebula structure also suggests that the enhancement of mass loss at
the end of the AGB phase has occurred isotropically, but has ensued only in the
equatorial directions while ceasing in the polar directions. The present data
also show evidence for the prolate spheroidal distribution of matter in this
bipolar PN. The AGB mass loss history reconstructed in this PN is thus
consistent with what has been previously proposed based on the past optical and
mid-IR imaging surveys of the post-AGB shells.


title: Can a galaxy redshift survey measure dark energy clustering?

abstract:
  (abridged) A wide-field galaxy redshift survey allows one to probe galaxy
clustering at largest spatial scales, which carries an invaluable information
on horizon-scale physics complementarily to the cosmic microwave background
(CMB). Assuming the planned survey consisting of z~1 and z~3 surveys with areas
of 2000 and 300 square degrees, respectively, we study the prospects for
probing dark energy clustering from the measured galaxy power spectrum,
assuming the dynamical properties of dark energy are specified in terms of the
equation of state and the effective sound speed c_e in the context of an
adiabatic cold dark matter dominated model. The dark energy clustering adds a
power to the galaxy power spectrum amplitude at spatial scales greater than the
sound horizon, and the enhancement is sensitive to redshift evolution of the
net dark energy density, i.e. the equation of state. We find that the galaxy
survey, when combined with Planck, can distinguish dark energy clustering from
a smooth dark energy model such as the quintessence model (c_e=1), when
c_e<0.04 (0.02) in the case of the constant equation of state w_0=-0.9 (-0.95).
An ultimate full-sky survey of z~1 galaxies allows the detection when c_e<0.08
(0.04) for w_0=0.9 (-0.95). We also investigate a degeneracy between the dark
energy clustering and the non-relativistic neutrinos implied from the neutrino
oscillation experiments, because the two effects both induce a scale-dependent
modification in the galaxy power spectrum shape at largest spatial scales
accessible from the galaxy survey. It is shown that a wider redshift coverage
can efficiently separate the two effects by utilizing the different redshift
dependences, where dark energy clustering is apparent only at low redshifts
z<1.


title: N-flationary magnetic fields

abstract:
  There is increasing interest in the role played by pseudo Nambu-Goldstone
bosons (pNGBs) in the construction of string-inspired models of inflation. In
these models the inflaton is expected to be coupled to gauge fields, and will
lead to the generation of magnetic fields that can be of cosmological interest.
We study the production of such fields mainly focusing on the model of
N-flation, where the collective effect of several pNGBs drives inflation.
Because the produced fields are maximally helical, inverse cascade processes in
the primordial plasma increase significantly their coherence length. We discuss
under what conditions inflation driven by pNGBs can account for the observed
cosmological magnetic fields. A constraint on the parameters of this class of
inflationary scenarios is also derived by requiring that the magnetic field
does not backreact on the inflating background.


title: Averaging Spherically Symmetric Spacetimes in General Relativity

abstract:
  We discuss the averaging problem in general relativity, using the form of the
macroscopic gravity equations in the case of spherical symmetry in volume
preserving coordinates. In particular, we calculate the form of the correlation
tensor under some reasonable assumptions on the form for the inhomogeneous
gravitational field and matter distribution. On cosmological scales, the
correlation tensor in a Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW)
background is found to be of the form of a spatial curvature. On astrophysical
scales the correlation tensor can be interpreted as the sum of a spatial
curvature and an anisotropic fluid. We briefly discuss the physical
implications of these results.


title:
Measuring the Average Evolution of Luminous Galaxies at z<3: The
  Rest-frame Optical Luminosity Density, Spectral Energy Distribution, and
  Stellar Mass Density

abstract:
  (Abridged) We present the evolution of the volume averaged properties of the
rest-frame optically luminous galaxy population to z~3, determined from four
disjoint deep fields with optical to near-infrared wavelength coverage. We
select galaxies above a rest-frame V-band luminosity of 3x10^10 Lsol and
characterize their rest-frame UV through optical properties via the mean
spectral energy distribution (SED). To measure evolution we apply the same
selection criteria to a sample of galaxies from the Sloan Digital Sky Survey
and COMBO-17. The mean rest-frame 2200Ang through V-band SED becomes steadily
bluer with increasing redshift but at z<3 the mean SED falls within the range
defined by ``normal'' galaxies in the nearby Universe. We measure stellar
mass-to-light ratios (Mstar/L) by fitting models to the rest-frame UV-optical
SEDs and derive the stellar mass density. The stellar mass density in luminous
galaxies has increased by a factor of 3.5-7.9 from z=3 to z=0.1, including
field-to-field variance uncertainties. After correcting to total, the measured
mass densities at z<2 lie below the integral of the star formation rate (SFR)
density as a function of redshift as derived from UV selected samples. This may
indicate a systematic error in the mass densities or SFR(z) estimates. We find
large discrepancies between recent model predictions for the evolution of the
mass density and our results, even when our observational selection is applied
to the models. Finally we determine that Distant Red Galaxies (selected to have
J_s - K_s>2.3) in our LV selected samples contribute 30% and 64% of the stellar
mass budget at z~2 and z~ 2.8 respectively. These galaxies are largely absent
from UV surveys and this result highlights the need for mass selection of high
redshift galaxies.


title:
GALEX and Optical Light Curves of EF Eridanus During a Low State: the
  Puzzling Source of UV Light

abstract:
  Low state optical photometry of EF Eri during an extended low accretion state
combined with GALEX near and far UV time-resolved photometry reveals a source
of UV flux that is much larger than the underlying 9500K white dwarf, and that
is highly modulated on the orbital period. The near UV and optical light curves
can be modeled with a 20,000K spot but no spot model can explain both the large
amplitude FUV variations and the SED. The limitations of limb darkening,
cyclotron and magnetic white dwarf models in explaining the observations are
discussed.


title: Point-Source Power in 3 Year Wilkinson Microwave Anisotropy Probe Data

abstract:
  Using a set of multifrequency cross spectra computed from the 3 year WMAP sky
maps, we fit for the unresolved point-source contribution. For a white-noise
power spectrum, we find a Q-band amplitude of A=0.011 +/- 0.001 muK^2 sr
(antenna temperature), significantly smaller than the value of 0.017 +/- 0.002
muK^2 sr used to correct the spectra in the WMAP release. Modifying the
point-source correction in this way largely resolves the discrepancy that
Eriksen et al. found between the WMAP V- and W-band power spectra. Correcting
the co-added WMAP spectrum for both the low-l power excess due to a suboptimal
likelihood approximation--also reported by Eriksen et al.--and the high-l power
deficit due to oversubtracted point sources--presented in this Letter--we find
that the net effect in terms of cosmological parameters is an \~0.7 sigma shift
in n_s to larger values. For the combination of WMAP, BOOMERANG, and ACBAR
data, we find n_s=0.969 +/- 0.016, lowering the significance of n_s not equal
to 1 from ~2.7 sigma to ~2.0 sigma.


title:
Magnetohydronamic Evolution of HII Regions in Molecular Clouds:
  Simulation Methodology, Tests, and Uniform Media

abstract:
  We present a method for simulating the evolution of HII regions driven by
point sources of ionizing radiation in magnetohydrodynamic media, implemented
in the three-dimensional Athena MHD code. We compare simulations using our
algorithm to analytic solutions and show that the method passes rigorous tests
of accuracy and convergence. The tests reveal several conditions that an
ionizing radiation-hydrodynamic code must satisfy to reproduce analytic
solutions. As a demonstration of our new method, we present the first
three-dimensional, global simulation of an HII region expanding into a
magnetized gas. The simulation shows that magnetic fields suppress sweeping up
of gas perpendicular to magnetic field lines, leading to small density
contrasts and extremely weak shocks at the leading edge of the HII region's
expanding shell.


title: The radio structure of radio-quiet quasars

abstract:
  We investigate the radio emitting structures of radio-quiet active galactic
nuclei with an emphasis on radio-quiet quasars to study their connection to
Seyfert galaxies. We present and analyse high-sensitivity VLA radio continuum
images of 14 radio-quiet quasars and six Seyfert galaxies. Many of the low
redshift radio-quiet quasars show radio structures that can be interpreted as
jet-like outflows. However, the detection rate of extended radio structures on
arcsecond scales among our sample decreases with increasing redshift and
luminosity, most likely due to a lack of resolution. The morphologies of the
detected radio emission indicate strong interactions of the jets with the
surrounding medium. We also compare the radio data of seven quasars with
corresponding HST images of the [OIII] emitting narrow-line region (NLR). We
find that the scenario of interaction between the radio jet and the NLR gas is
confirmed in two sources by structures in the NLR gas distribution as
previously known for Seyfert galaxies. The extended radio structures of
radio-quiet quasars at sub-arcsecond resolution are by no means different from
that of Seyferts. Among the luminosities studied here, the morphological
features found are similar in both types of objects while the overall size of
the radio structures increases with luminosity. This supports the picture where
radio-quiet quasars are the scaled-up versions of Seyfert galaxies. In addition
to known luminosity relations we find a correlation of the NLR size and the
radio size shared by quasars and Seyferts.


title:
Robust Machine Learning Applied to Astronomical Datasets I: Star-Galaxy
  Classification of the SDSS DR3 Using Decision Trees

abstract:
  We provide classifications for all 143 million non-repeat photometric objects
in the Third Data Release of the Sloan Digital Sky Survey (SDSS) using decision
trees trained on 477,068 objects with SDSS spectroscopic data. We demonstrate
that these star/galaxy classifications are expected to be reliable for
approximately 22 million objects with r < ~20. The general machine learning
environment Data-to-Knowledge and supercomputing resources enabled extensive
investigation of the decision tree parameter space. This work presents the
first public release of objects classified in this way for an entire SDSS data
release. The objects are classified as either galaxy, star or nsng (neither
star nor galaxy), with an associated probability for each class. To demonstrate
how to effectively make use of these classifications, we perform several
important tests. First, we detail selection criteria within the probability
space defined by the three classes to extract samples of stars and galaxies to
a given completeness and efficiency. Second, we investigate the efficacy of the
classifications and the effect of extrapolating from the spectroscopic regime
by performing blind tests on objects in the SDSS, 2dF Galaxy Redshift and 2dF
QSO Redshift (2QZ) surveys. Given the photometric limits of our spectroscopic
training data, we effectively begin to extrapolate past our star-galaxy
training set at r ~ 18. By comparing the number counts of our training sample
with the classified sources, however, we find that our efficiencies appear to
remain robust to r ~ 20. As a result, we expect our classifications to be
accurate for 900,000 galaxies and 6.7 million stars, and remain robust via
extrapolation for a total of 8.0 million galaxies and 13.9 million stars.
[Abridged]


title:
Special and general relativity extended to allow for a variable light
  speed

abstract:
  There have been a number of papers proposing that the light speed of a
homogeneous and isotropic universe is variable. This paper outlines a simple
way that the vectors and tensors of special relativity can be extended to allow
such a variable light speed and show how the field equation of general
relativity can also be extended with particular application to such a universe.


title: An XMM-Newton Observation of the Massive Edge-on Sb Galaxy NGC 2613

abstract:
  We present an XMM-Newton observation of the massive edge-on Sb galaxy NGC
2613. We discover that this galaxy contains a deeply embedded active nucleus
with a 0.3-10 keV luminosity of 3.3x10^40 erg/s and a line-of-sight absorption
column of 1.2x10^23 cm^-2. Within the 25 mag/arcsec^2 optical B-band isophote
of the galaxy, we detect an additional 4 sources with an accumulated luminosity
of 4.3x10^39 erg/s. The bulk of the unresolved X-ray emission spatially follows
the near-infrared (NIR) K-band surface brightness distribution; the luminosity
ratio L_X/L_K ~ 8x10^-4 is consistent with that inferred from galactic discrete
sources. This X-ray-NIR association and the compatibility of the X-ray spectral
fit with the expected spectrum of a population of discrete sources suggest that
low-mass X-ray binaries (LMXBs) are the most likely emitters of the unresolved
emission in the disk region. The remaining unresolved emission is primarily due
to extraplanar hot gas. The luminosity of this gas is at least a factor of 10
less than that predicted by recent simulations of intergalactic gas accretion
by such a massive galaxy with a circular rotation speed V_c ~ 304 km/s^2 (Toft
et al. 2002). Instead, we find that the extraplanar hot gas most likely
represents discrete extensions away from the disk, including two
``bubble-like'' features on either side of the nucleus. These extensions appear
to correlate with radio continuum emission and, energetically, can be easily
explained by outflows from the galactic disk.


title:
Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies:
  II. Control of the \HII Region Parameters

abstract:
  We examine, from a theoretical viewpoint, how the physical parameters of HII
regions are controlled in both normal galaxies and in starburst environments.
These parameters are the HII region luminosity function, the time-dependent
size, the covering fraction of molecular clouds, the pressure in the ionized
gas and the ionization parameter. The factors which control them are the
initial mass function of the exciting stars, the cluster mass function, the
metallicity and the mean pressure in the surrounding interstellar medium. We
investigate the sensitivity of the H$\alpha$ luminosity to the IMF, and find
that this can translate to more than a factor two variation in derived star
formation rates. The molecular cloud dissipation timescale is estimated from a
case study of M17 to be $\sim1$ Myr for this object. Based upon HII luminosity
function fitting for nearby galaxies, we suggest that the \HII region cluster
mass function is fitted by a log-normal form peaking at $\sim 100 M_{\odot}$.
The cluster mass function continues the stellar IMF to higher mass. The
pressure in the HII regions is controlled by the mechanical luminosity flux
from the central cluster. Since this is closely related to the ionizing photon
flux, we show that the ionization parameter is not a free variable, and that
the diffuse ionized medium may be composed of many large, faint and old HII
regions. Finally, we derive theoretical probability distributions for the
ionization parameter as a function of metallicity and compare these to those
derived for SDSS galaxies.


title: The Virial Mass Function of Nearby SDSS Galaxy Clusters

abstract:
  We present a new determination of the cluster mass function and velocity
dispersion function in a volume $\sim10^7 h^3$Mpc$^{-3}$ using the Fourth Data
Release of the Sloan Digital Sky Survey (SDSS). We use the caustic technique to
remove foreground and background galaxies. The cluster virial mass function
agrees well with recent estimates from both X-ray observations and cluster
richnesses. The mass function lies between those predicted by the First-Year
and Three-Year WMAP data. We constrain the cosmological parameters $\Omega_m$
and $\sigma_8$ and find good agreement with WMAP and constraints from other
techniques. With the CIRS mass function alone, we estimate
$\Omega_m=0.24^{+0.14}_{-0.09}$ and $\sigma_8=0.92^{+0.24}_{-0.19}$, or
$\sigma_8=0.84\pm$0.03 when holding $\Omega_m=0.3$ fixed. We also use the WMAP
parameters as priors and constrain velocity segregation in clusters. Using the
First and Third-Year results, we infer velocity segregation of
$\sigma_{gxy}/\sigma_{DM}\approx0.94\pm$0.05 or 1.28$\pm$0.06 respectively. We
compare the velocity dispersion function of clusters to that of early-type
galaxies and conclude that clusters comprise the high-velocity end of the
velocity dispersion function of dark matter haloes. The evolution of cluster
abundances provides constraints on dark energy models; the mass function
presented here offers an important low redshift calibration benchmark.


title:
Stellar halos and elliptical galaxy formation: Origin of dynamical
  properties of the planetary nebular systems

abstract:
  Recent spectroscopic observations of planetary nebulae (PNe) in several
elliptical galaxies have revealed structural and kinematical properties of the
outer stellar halo regions. In order to elucidate the origin of the properties
of these planetary nebula systems (PNSs), we consider the merger scenario in
which an elliptical galaxy is formed by merging of spiral galaxies. Using
numerical simulations, we particularly investigate radial profiles of projected
PNe number densities, rotational velocities, and velocity dispersions of PNSs
extending to the outer halo regions of elliptical galaxies formed from major
and unequal-mass merging. We find that the radial profiles of the project
number densities can be fitted to the power-law and the mean number density in
the outer halos of the ellipticals can be more than an order of magnitude
higher than that of the original spiral's halo. The PNSs are found to show a
significant amount of rotation (V/sigma >0.5) in the outer halo regions ($R$
$>$ $5R_{\rm e}$) of the ellipticals. Two-dimensional velocity fields of PNSs
are derived from the simulations and their dependences on model parameters of
galaxy merging are discussed in detail. We compare the simulated kinematics of
PNSs with that of the PNS observed in NGC 5128 and thereby discuss advantages
and disadvantages of the merger model in explaining the observed kinematics of
the PNS. We also find that the kinematics of PNSs in elliptical galaxies are
quite diverse depending on the orbital configurations of galaxy merging, the
mass ratio of merger progenitor spirals, and the viewing angle of the galaxies.
This variation translates directly into possible biases by a factor of more
than two in observational mass estimation (abridged). ~ ~


title: HCN and HNC mapping of the protostellar core Cha-MMS1

abstract:
  Aims. The purpose of this study is to investigate the distributions of the
isomeric molecules HCN and HNC and estimate their abundance ratio in the
protostellar core Cha-MMS1 located in Chamaeleon {\sc i}.
  Methods. The core was mapped in the J=1-0 rotational lines of HCN, HNC, and
HN13C. The column densities of H13CN, HN13C, H15NC and NH3 were estimated
towards the centre of the core.
  Results. The core is well delineated in all three maps. The kinetic
temperature in the core, derived from the NH3 (1,1) and (2,2) inversion lines,
is 12.1+/-0.1 K. The HN13C/H13CN column density ratio is between 3 and 4, i.e.
similar to values found in several other cold cores. The HN13C/H15NC column
density ratio is about 7. In case no 15N fractionation occurs in HNC (as
suggested by recent modelling results), the HNC/HN13C abundance ratio is in the
range 30-40, which indicates a high degree of 13C fractionation in HNC.
Assuming no differential 13C fractionation the HCN and HNC abundances are
estimated to be about 7E-10 and about 2E-9, respectively, the former being
nearly two orders of magnitude smaller than that of NH3. Using also previously
determined column densities in Cha-MMS1, we can put the most commonly observed
nitrogenous molecules in the following order according to their fractional
abundances: X(NH3) > X(HC3N) > X(HNC) > X(HCN) > X(N2H+).
  Conclusions. The relationships between molecular abundances suggest that
Cha-MMS1 represents an evolved chemical stage, experiencing at present the
'late-time' cyanopolyyne peak. The possibility that the relatively high HNC/HCN
ratio derived here is only valid for the $^{13}$C isotopic substitutes cannot
be excluded on the basis of the present and other available data.


title: Constraining fundamental physics with the cosmic microwave background

abstract:
  The temperature anisotropies and polarization of the cosmic microwave
background (CMB) radiation provide a window back to the physics of the early
universe. They encode the nature of the initial fluctuations and so can reveal
much about the physical mechanism that led to their generation. In this
contribution we review what we have learnt so far about early-universe physics
from CMB observations, and what we hope to learn with a new generation of
high-sensitivity, polarization-capable instruments.


title:
The Upper Limit of Magnetic Field Strength in Dense Stellar Hadronic
  Matter

abstract:
  It is shown that in strongly magnetized neutron stars, there exist upper
limits of magnetic field strength, beyond which the self energies for both
neutron and proton components of neutron star matter become complex in nature.
As a consequence they decay within the strong interaction time scale. However,
in the ultra-strong magnetic field case, when the zeroth Landau level is only
occupied by protons, the system again becomes stable against strong decay.


title: Monte Carlo radiative transfer in protoplanetary disks

abstract:
  We present a new continuum 3D radiative transfer code, MCFOST, based on a
Monte-Carlo method. MCFOST can be used to calculate (i) monochromatic images in
scattered light and/or thermal emission, (ii) polarisation maps, (iii)
interferometric visibilities, (iv) spectral energy distributions and (v) dust
temperature distributions of protoplanetary disks. Several improvements to the
standard Monte Carlo method are implemented in MCFOST to increase efficiency
and reduce convergence time, including wavelength distribution adjustments,
mean intensity calculations and an adaptive sampling of the radiation field.
The reliability and efficiency of the code are tested against a previously
defined benchmark, using a 2D disk configuration. No significant difference (no
more than 10%, and generally much less) is found between the temperatures and
SEDs calculated by MCFOST and by other codes included in the benchmark. A study
of the lowest disk mass detectable by Spitzer, around young stars, is presented
and the colours of ``representative'' parametric disks are compared to recent
IRAC and MIPS Spitzer colours of solar-like young stars located in nearby star
forming regions.


title:
Eclipsing binaries observed with the WIRE satellite I. Discovery and
  photometric analysis of the new bright A0IV eclipsing binary Psi Centauri

abstract:
  Determinations of stellar mass and radius with realistic uncertainties at the
level of 1% provide important constraints on models of stellar structure and
evolution. We present a high-precision light curve of the A0IV star Psi
Centauri, from the star tracker on board the WIRE satellite and the Solar Mass
Ejection Imager camera on the Coriolis spacecraft. The data show that Psi Cen
is an eccentric eclipsing binary system with a relatively long orbital period.
The WIRE light curve extends over 28.7 nights and contains 41334 observations
with 2 mmag point-to-point scatter. The eclipse depths are 0.28 and 0.16 mag,
and show that the two eclipsing components of Psi Cen have very different
radii. As a consequence, the secondary eclipse is total. We find the
eccentricity to be e=0.55 with an orbital period of 38.8 days from combining
the WIRE light curve with data taken over two years from the Solar Mass
Ejection Imager camera. We have fitted the light curve with EBOP and have
assessed the uncertainties of the resulting parameters using Monte Carlo
simulations. The fractional radii of the stars and the inclination of the orbit
have random errors of only 0.1% and 0.01 degrees, respectively, but the
systematic uncertainty in these quantities may be somewhat larger. We have used
photometric calibrations to estimate the effective temperatures of the
components of Psi Cen to be 10450+-300 and 8800+-300 K, indicating masses of
about 3.1 and 2.0 Msun. There is evidence in the WIRE light curve for g-mode
pulsations in the primary star.


title:
The Cosmic Microwave Background and the Ionization History of the
  Universe

abstract:
  Details of how the primordial plasma recombined and how the universe later
reionized are currently somewhat uncertain. This uncertainty can restrict the
accuracy of cosmological parameter measurements from the Cosmic Microwave
Background (CMB). More positively, future CMB data can be used to constrain the
ionization history using observations. We first discuss how current
uncertainties in the recombination history impact parameter constraints, and
show how suitable parameterizations can be used to obtain unbiased parameter
estimates from future data. Some parameters can be constrained robustly,
however there is clear motivation to model recombination more accurately with
quantified errors. We then discuss constraints on the ionization fraction
binned in redshift during reionization. Perfect CMB polarization data could in
principle distinguish different histories that have the same optical depth. We
discuss how well the Planck satellite may be able to constrain the ionization
history, and show the currently very weak constraints from WMAP three-year
data.