title:
The Chemical Composition of Cepheids in the Milky Way and the Magellanic
  Clouds

abstract:
  We have measured the elemental abundances of 68 Galactic and Magellanic
Cepheids from FEROS and UVES high-resolution and high signal-to-noise spectra
in order to establish the influence of the chemical composition on the
properties of these stars (see Romaniello et al. 2005). Here we describe the
robust analytical procedure we have developed to accurately determine them. The
resulting iron abundances span a range between ~ -0.80 dex for stars in the
Small Magellanic Cloud and ~ +0.20 dex for the most metal-rich ones in the
Galaxy. While the average values for each galaxy are in good agreement with
non-pulsating stars of similar age, Cepheids display a significant spread. Thus
it is fundamental to measure the metallicity of individual stars.


title: The Milky Way and the Tully-Fisher relation

abstract:
  We present an updated estimate of the surface density and surface brightness
in B,V,I of the local Galactic disc, based on a model for the "Solar cylinder"
calibrated to reproduce Hipparcos and Tycho star counts. We discuss the
mass-to-light ratio of the local stellar disc and infer the global luminosity
of the Milky Way, which results underluminous with respect to the Tully-Fisher
relation.


title:
On the size distribution of sunspot groups in the Greenwich sunspot
  record 1874-1976

abstract:
  We investigate the size distribution of the maximum areas and the
instantaneous distribution of areas of sunspot groups using the Greenwich
sunspot group record spanning the interval 1874-1976. Both distributions are
found to be well described by log-normal functions. Using a simple model we can
transform the maximum area distribution into the instantaneous area
distribution if the sunspot area decay rates are also distributed log-normally.
For single-valued decay rates the resulting snapshot distribution is
incompatible with the observations. The current analysis therefore supports the
results of Howard (1992) and MartinezPillet (1993). It is not possible to
distinguish between a linear and a quadratic decay law, however, with the
employed data set.


title:
Molecular gas in the galaxy cluster Abell 262. CO observations of UGC
  1347 and other galaxies of the cluster

abstract:
  We present millimeter CO line emission observations of 12 galaxies within the
Abell 262 cluster, together with L_FIR data, in the context of a possible
molecular gas deficiency within the region of the cluster center. Several
indications of the presence of such a deficiency are highlighted and connected
to a model of cirrus-like cloud stripping. The model predicts a drop in the
average 100 micron flux density of galaxies in the core of the cluster compared
to the average 100 micron flux density in the outer regions, which is actually
indicated in the IRAS data of the cluster members. This drop is explained by
the decrease in the total hydrogen column density N(H) and, therefore, also
includes a decrease in the molecular gas content.
  In addition to results for the global CO content of the galaxy sample,
high-resolution interferometric CO(1-0) observations of one of the cluster
members, UGC 1347, exemplify the spatial distribution of the molecular gas in a
galaxy of the cluster. With these observations, it was possible to confirm the
existence of a bright off-nuclear CO-emission source and to derive molecular
masses and line ratios for this source and the nucleus.


title: Infrared Supernova Remnants in the Spitzer GLIMPSE Field

abstract:
  We have searched for infrared emission from supernova remnants (SNRs)
included in the Spitzer Galactic Legacy Infrared Mid-Plane Survey
Extraordinaire (GLIMPSE) field. At the positions of 100 known SNRs, we made
3.6, 4.5, 5.8, and 8.0 um band images covering the radio continuum emitting
area of each remnant. In-depth examinations of four band images based on the
radio continuum images of SNRs result in the identification of sixteen infrared
SNRs in the GLIMPSE field. Eight SNRs show distinct infrared emission in nearly
all the four bands, and the other eight SNRs are visible in more than one band.
We present four band images for all identified SNRs, and RGB-color images for
the first eight SNRs. These images are the first high resolution (<2") images
with comparative resolution of the radio continuum for SNRs detected in the
mid-infrared region. The images typically show filamentary emission along the
radio enhanced SNR boundaries. Most SNRs are well identified in the 4.5 and 5.8
um bands. We give a brief description of the infrared features of the
identified SNRs.


title:
Cosmological constraints on f(R) gravity theories within the Palatini
  approach

abstract:
  We investigate f(R) theories of gravity within the Palatini approach and show
how one can determine the expansion history, H(a), for an arbitrary choice of
f(R). As an example, we consider cosmological constraints on such theories
arising from the supernova type Ia, large scale structure formation and cosmic
microwave background observations. We find that best fit to the data is a
non-null leading order correction to the Einstein gravity, but the current data
exhibits no significant preference over the concordance LCDM model. Our results
show that the often considered 1/R models are not compatible with the data. The
results demonstrate that the background expansion alone can act as a good
discriminator between modified gravity models when multiple data sets are used.


title:
The Milky Way Tomography with SDSS: I. Stellar Number Density
  Distribution

abstract:
  Abridged: We estimate the distances to ~48 million stars detected by the
Sloan Digital Sky Survey and map their 3D number density distribution in 100 <
D < 20 kpc range over 6,500 deg^2 of sky. The data show strong evidence for a
Galaxy consisting of an oblate halo, a disk component, and a number of
localized overdensities with exponential disk parameters (bias-corrected for an
assumed 35% binary fraction) H_1 = 300 pc, L_1 = 2600 pc, H_2 = 900 pc, L_2 =
3600 pc, and local density normalization of 12%. We find the halo to be oblate,
with best-fit axis ratio c/a = 0.64, r^{-2.8} profile, and the local
halo-to-thin disk normalization of 0.5%. We estimate the errors of derived
model parameters to be no larger than ~20% (disk scales) and ~10% (thick disk
normalization). While generally consistent with the above model, the density
distribution shows a number of statistically significant localized deviations.
We detect two overdensities in the thick disk region at (R, Z) ~ (6.5, 1.5)kpc
and (R, Z) ~ (9.5, 0.8) kpc, and a remarkable density enhancement in the halo
covering >1000deg^2 of sky towards the constellation of Virgo, at distances of
~6-20 kpc. Compared to a region symmetric with respect to the l=0 line, the
Virgo overdensity is responsible for a factor of 2 number density excess and
may be a nearby tidal stream or a low-surface brightness dwarf galaxy merging
with the Milky Way. After removal of the resolved overdensities, the remaining
data are consistent with a smooth density distribution; we detect no evidence
of further unresolved clumpy substructure at scales ranging from ~50pc in the
disk, to ~1 - 2 kpc in the halo.


title: The Metallicity Dependence of the Cepheid Period-Luminosity Relation

abstract:
  We have assessed the influence of the stellar iron content on the Cepheid
Period-Luminosity (PL) relation by relating the V band residuals from the
Freedman et al (2001) PL relation to [Fe/H] for 68 Galactic and Magellanic
Cloud Cepheids. The iron abundances were measured from FEROS and UVES
high-resolution and high signal-to-noise optical spectra. Our data indicate
that the stars become fainter as metallicity increases, until a plateau or
turnover point is reached at about solar metallicity. This behavior appears at
odds both with the PL relation being independent from iron abundance and with
Cepheids becoming monotonically brighter as metallicity increases (e.g.
Kennicutt et al 1998, Sakai et al 2004).


title: Relativistic Fermi acceleration with shock compressed turbulence

abstract:
  This paper presents numerical simulations of test particle Fermi acceleration
at relativistic shocks of Lorentz factor Gamma_sh = 2-60, using a realistic
downstream magnetic structure obtained from the shock jump conditions. The
upstream magnetic field is described as pure Kolmogorov turbulence; the
corresponding downstream magnetic field lies predominantly in the plane
tangential to the shock surface and the coherence length is smaller along the
shock normal than in the tangential plane. Acceleration is nonetheless
efficient and leads to powerlaw spectra with index s = 2.6-2.7 at large shock
Lorentz factor Gamma_sh >> 1, markedly steeper than for isotropic scattering
downstream. The acceleration timescale t_acc in the upstream rest frame becomes
a fraction of Larmor time t_L in the ultra-relativistic limit, t_acc ~ 10
t_L/Gamma_sh. Astrophysical applications are discussed, in particular the
acceleration in gamma-ray bursts internal and external shocks.


title: Back-Reaction: A Cosmological Panacea

abstract:
  We present a solution to the dark energy problem in terms of the Effective
Energy Momentum Tensor (EMT) of cosmological perturbations. The approach makes
use of the gravitational back-reaction of long wavelength (super-Hubble)
fluctuation modes on the background metric. Our results indicate that,
following preheating, the energy density associated with back-reaction is
sub-dominant and behaves as a tracker during the radiation era. At the onset of
matter domination, however, the effects of back-reaction begin to grow relative
to the matter density and the associated equation of state quickly approaches
that of a cosmological constant. Using standard values for the preheating
temperature and the amplitude of the inflaton following preheating, we show
that this mechanism leads to a very natural explanation of dark energy. We
comment on other recent attempts to explain the dark energy using back-reaction
and their relation to our work.


title: A User-oriented Comparison of the Techniques for 3D Spectroscopy

abstract:
  A comparison of the most popular techniques for 3D spectroscopy is presented
in a way which should hopefully be useful for astronomers intending to use
these techniques. Integral field spectroscopy, slitless spectroscopy, tunable
imaging filters, imaging Fourier transform spectroscopy, and energy-resolving
detectors are included in their different implementation. Their relative
advantages and disadvantages are discussed in view of the possible scientific
application.


title: Where are the missing cosmic metals ?

abstract:
  The majority of the heavy elements produced by stars 2 billion years after
the Big Bang (redshift z~3) are presently undetected at those epochs. We
propose a solution to this cosmic `missing metals' problem in which such
elements are stored in gaseous halos produced by supernova explosions around
star-forming galaxies. By using data from the ESO/VLT Large Program, we find
that:(i) only 5%-9% of the produced metals reside in the cold phase, the rest
being found in the hot (log T=5.8-6.4) phase; (ii) 1%-6% (3%-30%) of the
observed CIV (OVI) is in the hot phase. We conclude that at z~3 more than 90%
of the metals produced during the star forming history can be placed in a hot
phase of the IGM, without violating any observational constraint. The observed
galaxy mass-metallicity relation, and the intergalactic medium and intracluster
medium metallicity evolution are also naturally explained by this hypothesis.


title: Quantitative spectroscopic analysis of and distance to SN1999em

abstract:
  This work presents a detailed quantitative spectroscopic analysis of, and the
determination of the distance to, the type II supernovae (SN) SN1999em with
CMFGEN (Dessart & Hillier 2005a), based on spectrophotometric observations at
eight dates up to 40 days after discovery. We use the same iron-group metal
content for the ejecta, the same power-law density distribution (with exponent
n~10), and a Hubble-velocity law at all times. We adopt a H/He/C/N/O abundance
pattern compatible with CNO-cycle equilibrium values for a RSG/BSG progenitor,
with C/O enhanced and N depleted at later times. Based on our synthetic fits to
spectrophotometric observations of SN1999em, we obtain a distance of 11.5Mpc,
similar to that of Baron et al. (2004) and the Cepheid distance to the galaxy
host of 11.7Mpc (Leonard et al. 2003). Similarly, based on such models, the
Expanding Photosphere Method (EPM) delivers a distance of 11.6Mpc, with
negligible scatter between photometric bandpass sets; there is thus nothing
wrong with the EPM as such. Previous determinations using the tabulated
correction factors of Eastman et al. (1996) all led to 30-50% underestimates:
we find that this is caused by 1) an underestimate of the correction factors
compared to the only other study of the kind by Dessart & Hillier (2005b), 2) a
neglect of the intrinsic >20% scatter of correction factors, and 3) the use of
the EPM at late times when severe line blanketing makes the method inaccurate.
The need of detailed model computations for reliable EPM distance estimates
thus defeats the appeal and simplicity of the method. However, detailed fits to
SN optical spectra, based on tailored models for individual SN observations,
offers a promising approach to obtaining distances with 10-20% accuracy, either
through the EPM or a la Baron et al. (2004).


title:
Dust Dynamics, Surface Brightness Profiles, and Thermal Spectra of
  Debris Disks: The Case of AU Mic

abstract:
  AU Microscopii is a 12 Myr old M dwarf that harbors an optically thin,
edge-on disk of dust. The scattered light surface brightness falls with
projected distance b from the star as b^-a; within b = 43 AU, a = 1-2, while
outside 43 AU, a = 4-5. We devise a theory to explain this profile. At a
stellocentric distance r = r_BR = 43 AU, we posit a ring of parent bodies on
circular orbits: the "birth ring," wherein micron-sized grains are born from
the collisional attrition of parent bodies. The "inner disk" at r < r_BR
contains grains that migrate inward by corpuscular and Poynting-Robertson (CPR)
drag. The "outer disk" at r > r_BR comprises grains just large enough to remain
bound to the star, on orbits rendered highly eccentric by stellar wind and
radiation pressure. How the vertical optical depth tau scales with r depends on
the fraction of grains that migrate inward by CPR drag without suffering a
collision. If this fraction is large, the inner disk and birth ring share the
same optical depth, and tau scales as r^-5/2 in the outer disk. By contrast,
under collision-dominated conditions, the inner disk is empty, and tau scales
as r^-3/2 outside. These scaling relations, which we derive analytically and
confirm numerically, are robust against uncertainties in the grain size
distribution. By simultaneously modeling the surface brightness and thermal
spectrum, we break model degeneracies to establish that the AU Mic system is
collision-dominated, and that its narrow birth ring contains a lunar mass of
decimeter-sized bodies. The inner disk is devoid of micron-sized grains; the
surface brightness at b < 43 AU arises from light forward scattered by the
birth ring. Inside b = 43 AU, the disk's V-H color should not vary with b;
outside, the disk must become bluer as ever smaller grains are probed.


title:
The massive eclipsing LMC Wolf-Rayet binary BAT99-129. 1 Orbital
  parameters, hydrogen content and spectroscopic characteristics

abstract:
  BAT99-129 in the LMC is one among a handful of extra-galactic eclipsing
Wolf-Rayet binaries known. We present blue, medium-resolution, phase-dependent
NTT-EMMI spectra of this system that allow us to separate the spectra of the
two components of the binary and to obtain a reliable orbital solution for both
stars. We assign an O5V spectral type to the companion, and WN3(h)a to the
Wolf-Rayet component. We discuss the spectroscopic characteristics of the
system: luminosity ratio, radii, rotation velocities. We find a possible
oversynchronous rotation velocity for the O star. Surprisingly, the extracted
Wolf-Rayet spectrum clearly shows the presence of blueshifted absorption lines,
similar to what has been found in all single hot WN stars in the SMC and some
in the LMC. We also discuss the presence of such intrinsic lines in the context
of hydrogen in SMC and LMC Wolf-Rayet stars, WR+O binary evolution and GRB
progenitors. Altogether, BAT99~129 is the extragalactic counterpart of the
well-known Galactic WR binary V444 Cygni.


title:
Secular variability of the longitudinal magnetic field of the Ap star
  gamma Equ

abstract:
  We present an analysis of the secular variability of the longitudinal
magnetic field B_e in the roAp star gamma Equ (HD 201601). Measurements of the
stellar magnetic field B_e were mostly compiled from the literature, and append
also our 33 new B_e measurements which were obtained with the 1-m optical
telescope of Special Astrophysical Observatory (Russia). All the available data
cover the time period of 58 years, and include both phases of the maximum and
minimum B_e. We determined that the period of the long-term magnetic B_e
variations equals 91.1 +/- 3.6 years, with B_e (max) = + 577 +/- 31 G and B_e
(min) = -1101 +/- 31 G.


title: The First INTEGRAL AGN Catalog

abstract:
  We present the first INTEGRAL AGN catalog, based on observations performed
from launch of the mission in October 2002 until January 2004. The catalog
includes 42 AGN, of which 10 are Seyfert 1, 17 are Seyfert 2, and 9 are
intermediate Seyfert 1.5. The fraction of blazars is rather small with 5
detected objects, and only one galaxy cluster and no star-burst galaxies have
been detected so far. A complete subset consists of 32 AGN with a significance
limit of 7 sigma in the INTEGRAL/ISGRI 20-40 keV data. Although the sample is
not flux limited, the distribution of sources shows a ratio of obscured to
unobscured AGN of 1.5 - 2.0, consistent with luminosity dependent unified
models for AGN. Only four Compton-thick AGN are found in the sample. Based on
the INTEGRAL data presented here, the Seyfert 2 spectra are slightly harder
(Gamma = 1.95 +- 0.01) than Seyfert 1.5 (Gamma = 2.10 +- 0.02) and Seyfert 1
(Gamma = 2.11 +- 0.05).


title:
X-Ray Observations of V4641 SGR (= SAX J1819.3-2525) During the Brief
  and Violent Outburst of 2003

abstract:
  We present the results of detailed analysis of pointed X-ray observations by
RXTE PCA/HEXTE of the black hole X-ray binary (BHXRB) system V4641 Sgr (= SAX
J1819.3-2525) during its outburst of August 2003. Soft X-ray (3-20 keV) flux
variations by factors of 10 or more on timescales of minutes or shorter were
seen. The rapid and strong variability of this source sets it apart from
typical XRBs. In spite of large luminosity fluctuations, the spectral state of
the source did not change significantly during the dwells which suggests that
the physical emission processes did not change much during the observations.
The energy spectra during the dwells were dominated by a hard Comptonized
powerlaw component, indicative of the canonical low/hard state observed in
other BHXRBs. No soft thermal component was found in three out of the four RXTE
pointings. However spectral deconvolution of the observation with largest
average luminosity suggests an obscured, hot accretion disk. During one of the
observations we detected a short term (about 100s) soft X-ray dropout which is
apparently due to variability in the observed column density. Strong Fe
K$\alpha$ fluorescent emisssion line near 6.5 keV was detected with large
equivalent widths in the range of 700 - 1000eV. In the temporal domain, the
Fourier power spectra were dominated by red noise below a few Hz. Poisson noise
dominated at higher frequencies and no high frequency features were detected.
The strong Comptonized spectra, broad iron emission line, absence of disk
component in the spectra, absence of any timing variability above few Hz and
occasional large changes in the column density along the line-of-sight, all
support an enshrouded black hole with occasional outflow and a very dynamic
environment.


title:
On the role of strong gravity in polarization from scattering of light
  in relativistic flows

abstract:
  We study linear polarization due to scattering of light on a cloudlet of
particles, taking into account the radiation drag and the gravitational pull
exerted on them by a central body. Effects of special and general relativity
are included by connecting a model of Beloborodov (1998) for the local
polarization of scattered light with Abramowicz, Ellis & Lanza (1990) formalism
for the particle motion near an ultra-compact star. Compactness of the central
body and its luminosity are two critical parameters of the model. We discuss
the polarization magnitude of photons, which are Thomson-scattered into direct
and higher-order images. Importance of the latter is only moderate under
typical conditions, but they may give rise to distinct features, which we
explore in terms of a toy model. The scattered signal exhibits variations of
intensity and of polarization with mutual time-lags depending on the
beaming/focusing effects and the light travel time.


title:
Gas and stellar dynamics in NGC 1068. Probing the galactic gravitational
  potential

abstract:
  We present Sauron 2D spectrography of the central 1.5 kpc of the nearby Sey2
galaxy NGC1068, encompassing the well-known NIR inner bar. We have successively
disentangled the respective contributions of the ionized gas and stars, thus
deriving their 2D distribution and kinematics. The [OIII] and Hbeta emission
lines exhibit very different spatial distribution and kinematics, the latter
following inner spiral arms with clumps associated with star formation. Strong
inwards streaming motions are observed in both the Hbeta and [OIII] kinematics.
The stellar kinematics also exhibit clear signatures of a non-axisymmetric
tumbling potential, with a twist in both the velocity and h3 fields. We
re-examined the long-slit data of Shapiro et al (2003) using pPXF: a strong
decoupling of h3 is revealed, and the central decrease in h4 hinted in the
Sauron data is confirmed. These data also suggest that NGC1068 is a good
candidate for a so-called sigma-drop. We confirm the possible presence of two
pattern speeds. We also examine the stellar kinematics of bars formed in
N-body+SPH simulations built from axisymmetric initial conditions. These
successfully reproduce a number of properties observed in the 2D kinematics of
NGC1068, and the long-slit data, showing that the kinematic signature of the
NIR bar is imprinted in the stellar kinematics. The remaining differences
between the models and the observed properties are mostly due to the exclusion
of star formation and the lack of the primary large-scale oval/bar in the
simulations. These models suggest that the inner bar could drive a significant
amount of gas down to a scale of ~300 pc. This is consistent with the
interpretation of the sigma-drop in NGC1068 being the result of central gas
accretion followed by an episode of star formation.


title:
Electron distributions in X-Ray plasmas: spectral diagnostics with the
  3s/3d line ratio in Fe XVII

abstract:
  Efforts to benchmark astrophysical observations with X-ray laboratory
measurements have been stymied by observed and measured differences of up to a
factor of two in the ratio '3s/3d' of Fe XVII lines at ~17 \AA and ~15 \AA
respectively. Using the electron distribution function (EDF) as a new physical
parameter, we compute the Fe XVII line ratios and account for these
differences. Based on large-scale relativistic close coupling calculations
using the Breit-Pauli R-matrix method, revealing the precise effect of
resonances in collisional excitation, we employ collisional-radiative models
using cross sections convolved with both the Gaussian and the Maxwellian EDF.
Comparison with astrophysical observations and laboratory measurements
demonstrates that (a) the 3s/3d line ratio depends not only on the EDF but also
on the electron temperature/energy of the source, (b) plasma conditions in
experimental measurements and astrophysical observations may be quite
different, and (c) departure from a Maxwellian should manifest itself in, and
be used as a diagnostics of, particle distributions in plasmas.


title: Rational Galaxy Structure and its Disturbance

abstract:
  Why is there little dust in elliptical galaxies? Firstly, the universe is
rational and the rationality is the proportional density distribution in any
independent galaxy. Proportion means that the density distribution of stars is
orderly. For example, there are four giants standing in array. Their heights
are A, B, C, D, respectively, and A, B stand in the first row from left to
right, C, D in the second row from left to right. Proportion requires that A
divided by C be equal to B divided by D. Rational structures are smooth 2- (or
3-) dimensional structures, which are either circularly (spherically) symmetric
with respect to the center point, or bilaterally symmetric. Secondly, spiral
galaxy arms are linearly shaped, which are neither circularly symmetric nor
bilaterally symmetric. Therefore, arms are not rational structures. Arm
patterns exist only in spiral galaxies and they are weak compared with the main
disk structure. Therefore, the presence of arm structure is the disturbance to
the rational structure. Because arm patterns exist only in spiral galaxies and
only spiral galaxies present dust, I come to the critical answer to the above
question: any disturbance to rational structure produces cosmic dust. From now
on we call the disturbance to rational structure the cosmic impulse. Therefore,
the universe is originated not only rationally but also impulsively.


title: A Symmetry-induced Model of Elliptical Galaxy Patterns

abstract:
  S\'ersic (1968) generalized the de Vaucouleurs law which follows the
projected (observed) one dimensional radial profile of elliptical galaxies
closely and Dehnen (1993) proposed an analytical formula of the 3-dimensional
light distributions whose projected line profile resembles the de Vaucouleurs
law. This paper is involved to recover the Dehnen model and generalize the
model to account for galaxy elliptical shapes by means of curvilinear
coordinate systems and employing a symmetry principle. The symmetry principle
maps an orthogonal coordinate system to a light distribution pattern. The
coordinate system for elliptical galaxy patterns turns out to be the one which
is formed by the complex-plane reciprocal transformation $Z=1/W$. The resulting
spatial (3-dimensional) light distribution is spherically symmetric and has
infinite gradient at its centre, which is called spherical-nucleus solution and
is used to model galaxy central area. We can make changes of the coordinate
system by cutting out some column areas of its definition domain, the areas
containing the galaxy centre. The resulting spatial (3-dimensional) light
distributions are axisymmetric or triaxial and have zero gradient at the
centre, which are called elliptical-shape solutions and are used to model
global elliptical patterns. The two types of logarithmic light distributions
are added together to model full elliptical galaxy patterns. The model is a
generalization of the Dehnen model. One of the elliptical-shape solutions
permits realistic numerical calculation and is fitted to all R-band elliptical
images from the Frei {\it et al.}(1996)'s galaxy sample. The fitting is
satisfactory. This suggests that elliptical galaxy patterns can be represented
in terms of a few basic parameters.


title: A Note on High Energy Neutrinos from AGN Cores

abstract:
  Taking into account new physics and astronomy developments I give a revised
high energy neutrino flux for the AGN core model of Stecker, Done, Salamon and
Sommers


title: Radio emission from Colliding-Wind Binaries: Observations and Models

abstract:
  We have developed radiative transfer models of the radio emission from
colliding-wind binaries (CWB) based on a hydrodynamical treatment of the
wind-collision region (WCR). The archetype of CWB systems is the 7.9-yr period
binary WR140, which exhibits dramatic variations at radio wavelengths.
High-resolution radio observations of WR140 permit a determination of several
system parameters, particularly orbit inclination and distance, that are
essential for any models of this system. A model fit to data at orbital phase
0.9 is shown, and some short comings of our model described.


title: Contraction of Dark Matter Halos in Response to Condensation of Baryons

abstract:
  The cooling of baryons in the centers of dark matter halos leads to a more
concentrated dark matter distribution. This effect has traditionally been
calculated using the model of adiabatic contraction, which assumes spherical
symmetry, while in hierarchical formation scenarios halos grow via multiple
violent mergers. We test the adiabatic contraction model in high-resolution
cosmological simulations and find that the dissipation of gas indeed increases
the density of dark matter and steepens its radial profile compared to the case
without cooling. Although the standard model systematically overpredicts the
increase of dark matter density, a simple modification of the assumed invariant
from M(r)r to M(<r>)r, where <r> is the orbit-averaged particle position,
reproduces the simulated profiles within 10%.


title: The colliding-wind binary WR140: the particle acceleration laboratory

abstract:
  WR+O star binary systems exhibit synchrotron emission arising from
relativistic electrons accelerated where the wind of the WR star and that of
its massive binary companion collide - the wind-collision region (WCR). These
``colliding-wind'' binaries (CWB), provide an excellent laboratory for the
study of particle acceleration, with the same physical processes as observed in
SNRs, but at much higher mass, photon and magnetic energy densities. WR140 is
the best studied CWB, and high resolution radio observations permit a
determination of several system parameters, particularly orbit inclination and
distance, that are essential constraints for newly developed models of CWBs. We
show a model fit to the radio data at orbital phase 0.9, and show how these
models may be used to predict the high energy emission from WR140.


title: The Large Adaptive Reflector concept

abstract:
  Cost effective, new antenna technology is required to build the large
collecting area being planned for the next generation of radio telescopes. The
Large Adaptive Reflector (LAR) is a novel concept being developed in Canada to
meet this challenge. A prototype with a 200-350m diameter reflector, operating
up to 2 GHz with a bandwidth of 750 MHz is planned. With a collecting area up
to ~10% of the planned SKA, and an array feed capable of imaging a 0.3 deg^2
field-of-view, the prototype would address a number of the most compelling
questions in modern astrophysics.


title: HCN J=5-4 Emission in APM08279+5255 at z=3.91

abstract:
  We detect HCN J=5-4 emission from the ultraluminous quasar APM08279+5255 at
z=3.911 using the IRAM Plateau de Bure interferometer. This object is strongly
gravitationally lensed, yet still thought to be one of the most intrinsically
luminous objects in the Universe. The new data imply a line luminosity
L'_HCN(J=5-4) = 4.0+/-0.5 x 10^(10) K km/s pc^2. The ~440 km/s full width half
maximum of the HCN J=5-4 line matches that of the previously observed high-J CO
lines in this object and suggests that the emission from both species emerges
from the same region: a warm, dense circumnuclear disk. Simple radiative
transfer models suggest an enhanced abundance of HCN relative to CO in the
nuclear region of APM08279+5255, perhaps due to increased ionization, or
possibly the selective depletion of oxygen. The ratio of far-infrared
luminosity to HCN luminosity is at the high end of the range found for nearby
star forming galaxies, but comparable to that observed in the few high redshift
objects detected in the HCN J=1-0 line. This is the first clear detection of
high-J HCN emission redshifted into the 3-millimeter atmospheric window.


title:
BIMA CO Observation of EP Aqr the Semiregular Pulsating Star with a
  Double Component Line Profile

abstract:
  This paper reports the results of a Berkeley-Illinois-Maryland array
interferometric observation of EP Aqr, a semiregular pulsating star with a
double component line profile in the CO J=1-0 line. The broad component shows a
flat-top profile, and the narrow component shows a spiky strong peak. Though
the previous single dish observations suggested that the CO J=2-1 line exhibits
a Gaussian-like profile, the CO J=1-0 line does not. The spatial distributions
of both the narrow and broad components appears to be roughly round with the
same peak positions. No significant velocity gradient is seen. The
spatial-kinetic properties of the molecular envelope of EP Aqr are reminiscent
of a multiple shell structure model rather than a bipolar flow and disk model.
A problem of this interpretation is that no evidence of interaction between the
narrow and broad component regions is seen. A Gaussian-like feature seen in the
CO J=2-1 line might play a key role to understand the spatio-kinetic properties
of the molecular envelope of EP Aqr.


title:
Structural Parameters from Ground-based Observations of Newly Discovered
  Globular Clusters in NGC 5128

abstract:
  We have investigated a number of globular cluster candidates from a recent
wide-field study by Harris et al. (2004a) of the giant elliptical galaxy NGC
5128. We used the Magellan I telescope + MagIC camera under excellent seeing
(0.3"-0.6") and obtained very high resolution images for a sample of 44
candidates. Our images allow us to study the light profiles of the likely
clusters. This is the first ground-based study of structural parameters for
globular clusters outside the Local Group. We compare the psf-deconvolved
profiles with King models and derive structural parameters, ellipticities and
surface brightnesses. In general, our clusters are similar in size,
ellipticity, core radius and central surface brightness to their counterparts
in other galaxies, in particular those in NGC 5128 observed with HST by Harris
et al. (2002). However, they extend to higher ellipticities and larger
half-light radii than their Galactic counterparts. Combining our results with
those of Harris et al. fills in the gaps previously existing in $r_h - M_V$
parameter space and indicates that any substantial difference between presumed
distinct cluster types in this diagram, including for example the Faint Fuzzies
of Larsen & Brodie (2000) and the `extended, luminous' M31 clusters of Huxor et
al. (2005) is now removed and that clusters form a continuum in this diagram.
Indeed, this continuum now extends to the realm of the Ultra Compact Dwarfs. We
have carried out additional analysis to quantify the contamination by
background galaxies. This shows that, although galaxies cannot be easily told
apart from clusters in some of the structural diagrams, the combination of
excellent image quality and Washington photometry should limit the
contamination to roughly 10% of the population of cluster candidates.


title:
Variable Stars in the Large Magellanic Cloud: Discovery of Extragalactic
  W UMa Binaries

abstract:
  We observed a field in the disk of the LMC on two consecutive nights in
search of rapid variable stars. We have found two pulsating stars of type RRab
and delta Sct, and four binary stars, among the latter one sdB or CV below the
LMC blue Main Sequence and three very close binary systems on the MS. At least
one of the MS binaries, and possibly all three, are the first solar-type (W
UMa-type) contact binaries to be detected in any extragalactic system and
observed to obey the same Mv = Mv(log P, B-V) calibration as the Galactic
systems. Given the selection effects due to small amplitudes at faint
magnitudes, the frequency of such binaries in the disk of the LMC with its
large spread in population ages is not inconsistent with that in the disk of
our Galaxy, and contrasts with the lack of binaries found in earlier
observations of the much younger LMC cluster LW55.


title: Weak lensing constraints on galaxy halos

abstract:
  Weak gravitational lensing has become an important tool to study the
properties of dark matter halos around galaxies, thanks to the advent of large
panoramic cameras on 4m class telescopes. This area of research has been
developing rapidly in the past few years, and in these proceedings we present
some results based on the Red-Sequence Cluster Survey, thus highlighting what
can be achieved with current data sets. We present results on the measurement
of virial masses as a function of luminosity and the extent of dark matter
halos. Much larger surveys are underway or planned, which will result in an
impressive improvement in the accuracy of the measurements. However, the
interpretation of future results will rely more and more on comparison with
numerical simulations, thus providing direct tests of galaxy formation models.


title:
Relativistic Electromagnetic Mass Models: Charged Dust Distribution in
  Higher Dimensions

abstract:
  Electromagnetic mass models are proved to exist in higher dimensional theory
of general relativity corresponding to charged dust distribution. Along with
the general proof a specific example is also sited as a supporting candidate.


title:
Different Types of Fe K_\alpha Lines from Radiating Annuli near Black
  Holes

abstract:
  Recent X-ray observations of microquasars and Seyfert galaxies reveal the
broad emission lines in their spectra, which can arise in the innermost parts
of accretion disks. A theoretical analysis of observations and their
interpretations were discussed in a number of papers. We consider a radiating
annulus model to simulate spectral line shapes. That is a natural approximation
for narrow emitting circular rings without extra astrophysical assumptions
about emissivity laws. Recently Muller & Camenzind (2004) presented results of
their calculations and classified different types of spectral line shapes and
described their origin. We clarified their hypothesis about an origin of
doubled peaked and double horned line shapes. Based on results of numerical
simulations we showed that double peaked spectral lines arise almost for any
location of narrow emission rings (annuli) although Muller & Camenzind (2004)
suggested that such profiles arise for relatively flat space-times and typical
radii for emission region about 25 r_g. We showed that triangular spectral
lines could arise for nearest annuli and high inclination angles. We discuss a
possibility of appearance of narrow spectral line shapes as a result of
spiralling evolution of matter along quasi-circular orbits which could be
approximated by narrow annuli.


title: Dark energy models with time-dependent gravitational constant

abstract:
  Two phenomenological models of $\Lambda$, viz. $\Lambda \sim (\dot a/a)^2$
and $\Lambda \sim \ddot a/a$ are studied under the assumption that $G$ is a
time-variable parameter. Both models show that $G$ is inversely proportional to
time as suggested earlier by others including Dirac. The models considered here
can be matched with observational results by properly tuning the parameters of
the models. Our analysis shows that $\Lambda \sim \ddot a/a$ model corresponds
to a repulsive situation and hence correlates with the present status of the
accelerating Universe. The other model $\Lambda \sim (\dot a/a)^2$ is, in
general, attractive in nature. Moreover, it is seen that due to the combined
effect of time-variable $\Lambda$ and $G$ the Universe evolved with
acceleration as well as deceleration. This later one indicates a Big Crunch.


title: Dark energy with polytropic equation of state

abstract:
  Equation of state parameter plays a significant role for guessing the real
nature of dark energy. In the present paper polytropic equation of state
$p=\omega\rho^n$ is chosen for some of the kinematical $\Lambda$-models viz.,
$\Lambda \sim (\dot a/a)^2$, $\Lambda \sim \ddot a/a$ and $\Lambda \sim \rho$.
Although in dust cases ($\omega=0$) closed form solutions show no dependency on
the polytropic index $n$, but in non-dust situations some new possibilities are
opened up including phantom energy with supernegative ($\omega<-1$) equation of
state parameter.


title:
XMM-Newton observations of bright ROSAT selected active galactic nuclei
  with low intrinsic absorption

abstract:
  We present a sample of twenty-one ROSAT bright active galactic nuclei (AGN),
representing a range of spectral classes, and selected for follow-up snap-shot
observations with XMM-Newton. The typical exposure was between 5-10 ks. The
objects were primarily selected on the bases of X-ray brightness and not on
hardness ratio; thus the sample cannot be strictly defined as a `soft' sample.
One of the main outcomes from the XMM-Newton observations was that all of the
AGN, including eleven type 1.8-2 objects, required low levels of intrinsic
absorption (nh < 10^21 cm^-2). The low absorption in type 2 systems is a
challenge to account for in the standard orientation-based unification model,
and we discuss possible physical and geometrical models which could elucidate
the problem. Moreover, there does not appear to be any relation between the
strength and shape of the soft excess, and the spectral classification of the
AGN in this sample. We further identify a number of AGN which deserve deeper
observations or further analysis: for example, the LINERs NGC 5005 and NGC
7331, where optically thin thermal and extended emission is detected, and the
narrow-line Seyfert 1 II Zw 177, which shows a broad emission feature at
5.8keV.


title: An X-ray view of Mrk 705: A borderline narrow-line Seyfert 1 galaxy

abstract:
  Mrk 705 exhibits optical properties of both narrow- and broad-line Seyfert 1
galaxies. We examine the X-ray properties of this borderline object utilising
proprietary and public data from Chandra, ASCA, ROSAT and RXTE, spanning more
than twelve years. Though long-term flux variability from the pointed
observations appears rather modest (about 3 times), we do find examples of rare
large amplitude outbursts in the RXTE monitoring data. There is very little
evidence of long-term spectral variability as the low- and high-energy spectra
appear constant with time. A 6.4 keV emission line is detected in the ASCA
spectra of Mrk 705, but not during the later, higher flux state Chandra
observation. However, the upper limit on the equivalent width of a line in the
Chandra spectrum is consistent with a constant-flux emission line and a
brighter continuum, suggesting that the line is emitted from distant material
such as the putative torus. Overall, the X-ray properties of Mrk 705 appear
typical of BLS1 activity.


title:
Pristine CNO abundances from Magellanic Cloud B stars II. Fast rotators
  in the LMC cluster NGC 2004

abstract:
  We present spectroscopic abundance analyses of three main-sequence B stars in
the young Large Magellanic Cloud cluster NGC 2004. All three targets have
projected rotational velocities around 130 km/s. Techniques are presented that
allow the derivation of stellar parameters and chemical abundances in spite of
these high v sin i values. Together with previous analyses of stars in this
cluster, we find no evidence among the main-sequence stars for effects due to
rotational mixing up to v sin i around 130 km/s. Unless the equatorial
rotational velocities are significantly larger than the v sin i values, this
finding is probably in line with theoretical expectations. NGC 2004/B30, a star
of uncertain evolutionary status located in the Blue Hertzsprung Gap, clearly
shows signs of mixing in its atmosphere. To verify the effects due to
rotational mixing will therefore require homogeneous analysis of statistically
significant samples of low-metallicity main-sequence B stars over a wide range
of rotational velocities.


title:
The Dynamic Cosmological Term $\Lambda$: Some Aspects of
  Phenomenological Models

abstract:
  Choosing a phenomenological model of $\Lambda$, viz. $\Lambda \sim \dot H$,
it has been shown that this model of $\Lambda$ is equivalent to other three
types of $\Lambda$, $\Lambda \sim (\dot a/a)^2$, $\Lambda \sim \ddot a/a$ and
$\Lambda \sim \rho$. Through an indirect approach, it has also been possible to
put a limit on the deceleration parameter $q$. It has been shown that if $q$
becomes less than -1, then this model can predict about the presence of phantom
energy.


title:
Evolution of damped Lyman alpha kinematics and the effect of spatial
  resolution on 21-cm measurements

abstract:
  We have investigated the effect of spatial resolution on determining
pencil-beam like velocity widths and column densities in galaxies. Three 21-cm
datasets are used, the HIPASS galaxy catalogue, a subset of HIPASS galaxies
with ATCA maps and a high-resolution image of the LMC. Velocity widths measured
from 21-cm emission in local galaxies are compared with those measured in
intermediate redshift Damped Lyman alpha (DLA) absorbers. We conclude that
spatial resolution has a severe effect on measuring pencil-beam like velocity
widths in galaxies. Spatial smoothing by a factor of 240 is shown to increase
the median velocity width by a factor of two. Thus any difference between
velocity widths measured from global profiles or low spatial resolution 21-cm
maps at z=0 and DLAs at z>1 cannot unambiguously be attributed to galaxy
evolution. The effect on column density measurements is less severe and the
values of dN/dz from local low-resolution 21-cm measurements are expected to be
overestimated by only ~10 per cent.


title: The outside-in formation of elliptical galaxies

abstract:
  In this paper we compare the predictions of a detailed multi-zone chemical
evolution model for elliptical galaxies with the very recent observations of
the galaxy NGC 4697. As a consequence of the earlier development of the wind in
the outer regions with respect to the inner ones, we predict an increase of the
mean stellar [<Mg/Fe>] ratio with radius, in very good agreement with the data
for NGC4697. This finding strongly supports the proposed outside-in formation
scenario for ellipticals. We show that, in spite of the good agreement found
for the [<Mg/Fe>] ratio, the predicted slope of the mass-weighted metallicity
gradient does not reproduce the one derived from observations, once a
calibration to convert indices into abundances is applied. This is explained as
the consequence of the different behaviour with metallicity of the
line-strength indices as predicted by a Single Stellar Population (SSP) and
those derived by averaging over a Composite Stellar Population (CSP). In order
to better address this issue, we calculate the theoretical ``G-dwarf''
distributions of stars as functions of both metallicity ([Z/H]) and [Fe/H],
showing that they are broad and asymmetric that a SSP cannot correctly mimick
the mixture of stellar populations at any given radius. We find that these
distributions differ from the ``G-dwarf'' distributions especially at large
radii,except for the one as a function of [Mg/Fe]. Therefore, we conclude that
in ellipticals the [Mg/Fe] ratio is the most reliable quantity to be compared
with observations and is the best estimator of the star formation timescale at
each radius.(abridged)


title:
Scenario of Accelerating Universe from the Phenomenological \Lambda-
  Models

abstract:
  Dark matter, the major component of the matter content of the Universe,
played a significant role at early stages during structure formation. But at
present the Universe is dark energy dominated as well as accelerating. Here,
the presence of dark energy has been established by including a time-dependent
$\Lambda$ term in the Einstein's field equations. This model is compatible with
the idea of an accelerating Universe so far as the value of the deceleration
parameter is concerned. Possibility of a change in sign of the deceleration
parameter is also discussed. The impact of considering the speed of light as
variable in the field equations has also been investigated by using a well
known time-dependent $\Lambda$ model.


title: On the shape of Superbubbles evolving in the Galactic Plane

abstract:
  The galactic supershells are cavities in the interstellar medium. These
shells can be explained by introducing the concept of superbubbles, the
theoretical result of multiple supernova. The superbubbles can be analytically
described if the ambient medium has a constant density both in the so-called
bursting phase and in the subsequent adiabatic expansion. In order to solve the
expansion of superbubbles in the ISM, which is a non-homogeneous medium, a
numerical technique is used that divides the sphere into many sectors. By
varying the time of the bursting phenomenon and the time over which the
phenomenon is followed, elliptical and hour-glass shapes or vertical walls can
be obtained. Application of the developed theory/code to the super-shell
associated with GW~46.4+5 and with GSH 238 allows us to say that the suggested
physical parameters are consistent with our theory. The map of the expanding
superbubble's velocity can be tentatively traced by generating random points on
the expanding surface. The structure of the galactic plane as a result of the
evolution of many super-bubbles was simulated by adopting the percolation
theory in order to generate new OB associations.


title:
The Geometric Calibration of the Planck satellite using Solar System
  Objects

abstract:
  The geometric calibration of the Planck satellite using the planetary
transits is investigated, together with the reconstruction of any offsets from
the nominal layout of the focal plane. The methods presented here may be
applied to a single focal plane transit of a planet, to find the values of the
geometric-calibration parameters at the epoch of the transit or all the
transits over the course of the mission. The pointing requirements are easily
met, with the pointing reconstruction being dominated by the errors due to the
star tracker.


title:
The early star generations: the dominant effect of rotation on the CNO
  yields

abstract:
  We examine the role of rotation on the evolution and chemical yields of very
metal--poor stars. The models include the same physics, which was applied
successfully at the solar $Z$ and for the SMC, in particular, shear diffusion,
meridional circulation, horizontal turbulence, and rotationally enhanced mass
loss. Models of very low $Z$ experience a much stronger internal mixing in all
phases than at solar $Z$. Also, rotating models at very low $Z$, contrary to
the usual considerations, show a large mass loss, which mainly results from the
efficient mixing of the products of the 3$\alpha$ reaction into the H--burning
shell. This mixing allows convective dredge--up to enrich the stellar surface
in heavy elements during the red supergiant phase, which in turn favours a
large loss of mass by stellar winds, especially as rotation also increases the
duration of this phase. On the whole, the low $Z$ stars may lose about half of
their mass. Massive stars initially rotating at half of their critical velocity
are likely to avoid the pair--instability supernova. The chemical composition
of the rotationally enhanced winds of very low $Z$ stars show large CNO
enhancements by factors of $10^3$ to $10^7$, together with large excesses of
$^{13}$C and $^{17}$O and moderate amounts of Na and Al. The excesses of
primary N are particularly striking. When these ejecta from the rotationally
enhanced winds are diluted with the supernova ejecta from the corresponding CO
cores, we find [C/Fe], [N/Fe],[O/Fe] abundance ratios that are very similar to
those observed in the C--rich, extremely metal--poor stars (CEMP). We show that
rotating AGB stars and rotating massive stars have about the same effects on
the CNO enhancements.


title:
The CORALIE survey for southern extrasolar planets XIV. HD 142022 b: a
  long-period planetary companion in a wide binary

abstract:
  We report precise Doppler measurements of HD 142022 obtained during the past
six years with the CORALIE echelle spectrograph at La Silla Observatory
together with a few additional observations made recently with the HARPS
echelle spectrograph. Our radial velocities reveal evidence of a planetary
companion with an orbital period P = 1928 +53-39 days, an eccentricity e = 0.53
+0.23-0.18, and a velocity semiamplitude K = 92 +102-29 m/s. The inferred
companion minimum mass is M2sini = 5.1 +2.6-1.5 MJup and the semimajor axis a =
3.03+/-0.05 AU. Only one full orbital revolution has been monitored yet, and
the periastron passage could not be observed since the star was too low on the
horizon. The eccentricity and velocity semiamplitude remain therefore quite
uncertain and the orbital solution is preliminary. HD 142022 is a
chromospherically inactive K0 dwarf, metal rich relative to the Sun, and is the
primary component of a wide binary. HD 142022 b is thus a new "planet in
binary" candidate, and its high eccentricity might be due to secular
interactions with the distant stellar companion.


title: A starquake model for Vela pulsar

abstract:
  Various neutron star (NS) models correspond to an unrealistic mass range
$\leq 0.5M_\odot$ for the Vela pulsar, if the observational constraints of the
glitch healing parameter in the starquake model ($Q = I_{\rm core}/I_{\rm
total} \leq 0.2$), are imposed on these models. However, we show that these
observational constraints yield a realistic mass range for NS models,
corresponding to a core given by the stiffest equations of state (EOS) and the
envelope is characterized by the well known EOS of adiabatic polytrope, if the
continuity of the adiabatic speed of sound together with pressure,
energy-density, and the two metric parameters is assured at the core-envelope
boundary of the models and this boundary is worked out on the basis of the
`compatibility criterion' for hydrostatic equilibrium. The models yield the
surface redshift $z_R \simeq 0.6913$ and mass $M \simeq 2.153 M_\odot$ for the
``central'' weighted mean value, $Q = 0.12 \pm 0.07$, of the glitch healing
parameter of the Vela pulsar. These values of mass and surface redshift can
increase upto $M \simeq 2.196 M_\odot$ and $z_R \simeq 0.7568$ (which
represents an ultra-compact object (UCO; $z_R \geq 0.73$)) respectively for the
upper weighted mean value of $Q \simeq 0.19$. However, for the lower weighted
mean value of $Q \simeq 0.05$, the mass and surface redshift can decrease upto
the values of $M \simeq 2.052 M_\odot$ and $z_R \simeq 0.6066$ respectively.
The observation of the lower bound on the energy of a $\gamma$-ray pulse at
about 0.30 MeV from the Vela pulsar in 1984 is in excellent agreement with the
results of this study, provided this energy could be interpreted as the energy
of a gravitationally redshifted electron-positron annihilation radiation from
the star's surface.


title:
HI absorption in 3C 49 and 3C 268.3. Probing the environment of Compact
  Steep Spectrum and GHz Peaked Spectrum sources

abstract:
  We present and discuss European VLBI Network UHF band spectral line
observations, made to localise the redshifted 21cm HI absorption known to occur
in the subgalactic sized compact steep spectrum galaxies 3C 49 and 3C 268.3. We
have detected HI absorption towards the western radio lobe of 3C 49 and the
northern lobe of 3C 268.3. However, we cannot rule out the presence of similar
amounts of HI towards the opposite and much fainter lobes. The radio lobes with
detected HI absorption (1) are brighter and closer to the core than the
opposite lobes; (2) are depolarized; and (3) are associated with optical
emission line gas. The association between the HI absorption and the emission
line gas, supports the hypothesis that the HI absorption is produced in the
atomic cores of the emission line clouds. Our results are consistent with a
picture in which compact steep spectrum sources interact with clouds of dense
gas as they propagate through their host galaxy. We suggest that the
asymmetries in the radio and optical emission can be due to interaction of a
two sided radio source with an asymmetric distribution of dense clouds in their
environment.


title:
A Sample of IRAS Infrared-Selected Seyfert 1.5 Galaxies: Infrared-Color
  $\alpha(60,25)$ Dominated Eigenvector 1

abstract:
  The well-documented E1 relationships are first extended to infrared color
$\alpha(60,25)$ and flux ratio [OIII]/H$\beta_{\rm{n}}$ by comparing emission
line properties to continuum properties in infrared wavelength. Both direct
correlations and a principle component analysis are used in a sample of 50 IRAS
IR-selected Seyfert 1.5 galaxies. In addition to confirm the correlations of E1
in Boroson & Green (1992), our Eigenvector 1 turns out to be dominated by
mid-infrared color $\alpha$(60,25), and most strongly effected by RFe,
[OIII]/H$\beta_{\rm{n}}$, and EW(H$\beta_{\rm{b}}$). Our analysis indicate that
the objects with large E1 tend to co-existent with relatively young nuclear
stellar populations, which implies that the E1 is related with nuclear
starformation history. The IR-dominated Eigenvector 1 can be, therefore,
inferred to be interpreted as ``age'' of AGN. In confirmation of Xu et al.
(2003), it is clear that the extreme Seyfert galaxies with both large RFe and
large [OIII]/H$\beta_{\rm{n}}$ are rare in our Universe.


title:
Thermal SiO and H$^{13}$CO$^+$ Line Observations of the Dense Molecular
  Cloud G0.11$-$0.11 in the Galactic Center region

abstract:
  We obtained the first view in H$^{13}$CO$^+$ $J=1-0$ and a high resolution
map in thermal SiO lines of G0.11$-$0.11, which is a molecular cloud situated
between the Galactic Center radio arc and Sgr A. From a comparison with
previous line observations, we found that the H$^{13}$CO$^+$ $J=1-0$ line is
optically thin, whereas the thermal SiO lines are optically thick. The line
intensity in H$^{13}$CO$^+$ $J=1-0$ shows that the cloud has a large column
density, up to $N(\mathrm{H}_2)=(6-7)\times10^{23} \mathrm{cm^{-2}}$, which
corresponds to about 640--740 mag in $A_{\mathrm{V}}$ or 10--12 mag in
$A_{25\mu\mathrm{m}}$. The estimated column density is the largest known of any
even in the Galactic center region. We conclude from the intensity ratio of SiO
$J=1-0$ to CS $J=1-0$ that emitting gas is highly inhomogeneous for SiO
abundance on a scale smaller than the beam width $\sim$35\arcsec.


title: Swift and optical observations of GRB 050401

abstract:
  We present the results of the analysis of gamma-ray and X-ray data of GRB
050401 taken with the Swift satellite, together with a series of ground-based
follow-up observations. The Swift X-ray light curve shows a clear break at
about 4900 seconds after the GRB. The decay indices before and after the break
are consistent with a scenario of continuous injection of radiation from the
'central engine' of the GRB to the fireball. Alternatively, this behaviour
could result if ejecta are released with a range of Lorentz factors with the
slower shells catching up the faster at the afterglow shock position. The two
scenarios are observationally indistinguishable. The GRB 050401 afterglow is
quite bright in the X-ray band but weak in the optical, with an optical to
X-ray flux ratio similar to those of 'dark bursts'. We detect a significant
amount of absorption in the X-ray spectrum, with N_H = (1.7 +/- 0.2) x 10^22
cm^-2 at a redshift of z=2.9, which is typical of a dense circumbust medium.
Such high column density implies an unrealistic optical extinction of 30
magnitudes if we adopt the Galactic extinction law, which would not consistent
with optical detection of the afterglow. This suggests that the extinction law
is different from the Galactic one.


title: A compact flare eclipsed in the corona of SV Cam

abstract:
  The eclipsing active binary SV Cam (G0V/K6V, P_0.593071 d) was observed with
XMM-Newton during two campaigns in 2001 and 2003. No eclipses in the quiescent
emission are clearly identified, but a flare was eclipsed during the 2001
campaign, allowing us to strongly constrain, from purely geometrical
considerations, the position and size of the event: the flare is compact and it
is formed at a latitude below 65 deg. The size, temperature and Emission
Measure of the flare imply an electron density of log n_e (cm^-3)~10.6-13.3 and
a magnetic field of ~65-1400 G in order to confine the plasma, consistent with
the measurements that are obtained from density-sensitive line ratios in other
similar active stars. Average emission seems to come from either extended or
polar regions because of lack of eclipses. The Emission Measure Distribution,
coronal abundances and characteristics of variability are very similar to other
active stars such as AB Dor (K1V).


title: Mass-to-light ratios of ellipticals in LCDM

abstract:
  We use the mass-to-light gradients in early-type galaxies to infer the global
dark matter fraction, f_d=M_d/M_*, for these systems. We discuss implications
about the total star formation efficiency in dark-matter halos and show that
the trend of $f_{\rm d}$ with mass produces virial mass-to-light ratios which
are consistent with semi-analitical models. Preliminary kurtosis analysis of
the quasi-constant M/L galaxies in Romanowsky et al. seems at odd with Dekel et
al. simulations.


title: Outer Pseudoring in the Galaxy

abstract:
  The kinematical features of the Sagittarius (R=5.7 kpc), Carina (R=6.5 kpc),
Cygnus (R=6.8 kpc), and Perseus (R=8.2 kpc) arm fragments suggest the existence
of two spiral patterns rotating at different angular velocities in the Galaxy.
The inner spiral pattern represented by the Sagittarius arm rotates at the
angular velocity of the bar, Omega=60(+/-5) km s-1 kpc-1. The outer spiral
pattern, which consists of the Carina, Cygnus and Perseus arms, rotates at a
smaller angular velocity, Omega=12-22 km s-1 kpc-1. The existence of the outer
slow tightly wound spiral pattern and the inner fast spiral pattern can be
explained in terms of the results of numerical simulations of the dynamics of
the outer pseudoring. The OLR of the bar must be located between the
Sagittarius and Carina arms. The Cygnus arm appears as a connecting link
between the fast and slow spiral patterns.


title: Spectral energy distribution for GJ406

abstract:
  We present results of modelling the bulk of the spectral energy distribution
(0.35 - 5 micron) for GJ406 (M6V). Synthetic spectra were calculated using the
NextGen, Dusty and Cond model atmospheres and incorporate line lists for H2O,
TiO, CrH, FeH, CO, MgH molecules as well as the VALD line list of atomic lines.
A comparison of synthetic and observed spectra gives Tef = 2800 +/- 100 K. We
determine M$_bol = 12.13 +/- 0.10 for which evolutionary models by Baraffe et
al. (2003) suggest an age of around 0.1 -- 0.35 Gyr consistent with its high
activity. The age and luminosity of GJ406 correspond to a wide range of
plausible masses (0.07 -- 0.1 Msun).


title: Forced Oscillations in Fluid Tori and Quasi-Periodic Oscillations

abstract:
  The kilo-Hertz Quasi--Periodic Oscillations in X-ray binaries could originate
within the accretion flow, and be a signature of non--linear fluid oscillations
and mode coupling in strong gravity. The possibility to decipher these systems
will impact our knowledge of fundamental parameters such as the neutron star
mass, radius, and spin. Thus they offer the possibility to constrain the
nuclear equation of state and the rotation parameter of stellar--mass black
holes. We review the general properties of these oscillations from a
hydrodynamical point of view, when the accretion flow is subject to external
perturbations and summarize recent results.


title:
Emission lines from rotating proto-stellar jets with variable velocity
  profiles. I. Three-dimensional numerical simulation of the non-magnetic case

abstract:
  Using the Yguazu-a three-dimensional hydrodynamic code, we have computed a
set of numerical simulations of heavy, supersonic, radiatively cooling jets
including variabilities in both the ejection direction (precession) and the jet
velocity (intermittence). In order to investigate the effects of jet rotation
on the shape of the line profiles, we also introduce an initial toroidal
rotation velocity profile, in agreement with some recent observational evidence
found in jets from T Tauri stars which seems to support the presence of a
rotation velocity pattern inside the jet beam, near the jet production region.
Since the Yguazu-a code includes an atomic/ionic network, we are able to
compute the emission coefficients for several emission lines, and we generate
line profiles for the H, [O I]6300, [S II]6716 and [N II]6548 lines. Using
initial parameters that are suitable for the DG Tau microjet, we show that the
computed radial velocity shift for the medium-velocity component of the line
profile as a function of distance from the jet axis is strikingly similar for
rotating and non-rotating jet models. These findings lead us to put forward
some caveats on the interpretation of the observed radial velocity distribution
from a few outflows from young stellar objects, and we claim that these data
should not be directly used as a doubtless confirmation of the
magnetocentrifugal wind acceleration models.


title: The Young Open Cluster NGC 2129

abstract:
  The first CCD UBV(RI) photometric study in the area of the doubtful open
cluster NGC 2129 is presented. Photometry of a field offset 15 arcmin northward
is also provided, to probe the Galactic disk population toward the cluster.
Using star counts, proper motions from the UCAC2 catalog, colour-magnitude and
colour-colour diagrams we demonstrate that NGC 2129 is a young open cluster.
The cluster radius is 2.5 arcmin, and across this region we find evidence of
significant differential reddening, although the reddening law seems to be
normal toward its direction. Updated estimates of the cluster fundamental
parameters are provided. The mean reddening is found to be E(B-V)=0.80$\pm$0.08
and the distance modulus is $(m-M)_o$= 11.70$\pm0.30$. Hence, NGC 2129 is
located at 2.2$\pm$0.2 kpc from the Sun inside the Local spiral arm. The age
derived from 37 photometrically selected members is estimated to be
approximately 10 million years. These stars are used to provide new estimates
of the cluster absolute proper motion components.


title:
The Fate of Former Companions to Hypervelocity Stars Originating at the
  Galactic Center

abstract:
  The hypervelocity star SDSS J090745.0+024507 in the halo of the Milky Way
galaxy (Brown et al. 2005) most likely originated from the breakup of a binary
star system by the central black hole, SgrA* (Hills 1988). We examine the fate
of former binary companions to similar hypervelocity stars (HVSs) by simulating
600 different binary orbits around SgrA* with a direct N-body integration code.
For some orbital parameters, the binary breakup process leads to HVSs with
ejection velocities that are almost an order of magnitude larger than the
velocity observed for SDSS J090745.0+024507. The former companion stars
populate highly eccentric orbits which resemble the observed orbits for some of
the stars nearest to SgrA*.


title: Caustics in Dark Matter Haloes

abstract:
  Caustics are formally singular structures, with infinite density, that form
in collisionless media. The non-negligible velocity dispersion of dark matter
particles renders their density finite. We evaluate the maximum density of the
caustics within the framework of secondary infall model of formation of dark
matter haloes. The result is then used to demonstrate that caustics can be
probed by properly stacking the weak-lensing signal of about 600 haloes. CFHTLS
accompanied by X-ray observations and the space-based experiments like SNAP or
DUNE can provide us with the required statistics and hence a way of
distinguishing between the viable dark matter particle candidates. The
extension of our results to more realistic models including the effects of
mergers of haloes is briefly outlined.


title: The Search for Dark Matter, Einstein's Cosmology and MOND

abstract:
  The discovery of dark matter particles would conclusively reject the MOND
theory. MOND may violate Einstein's Strong Equivalence principle. However, as
we show, there is already evidence that MOND is likely not required. MOND was
invented to explain the rotation velocities of stars far into the galactic
halos. Dark Matter also explains this same effect.
  These both use a gravity probe of the I/R^2 law. We show that non gravity
probes determine the same value for the amount of dark matter that does not
involve modifications of gravity. Using Occam's Razor this coincidence is best
explained by the existence of dark matter.


title: Measuring the Spin of Spiral Galaxies

abstract:
  We compute the angular momentum, the spin parameter and the related
distribution function for Dark Matter halos hosting a spiral galaxy. We base on
scaling laws, inferred from observations, that link the properties of the
galaxy to those of the host halo; we further assume that the Dark Matter has
the same total specific angular momentum of the baryons. Our main results are:
(i) we find that the gas component of the disk significantly contributes to the
total angular momentum of the system; (ii) by adopting for the Dark Matter the
observationally supported Burkert profile, we compute the total angular
momentum of the disk and its correlation with the rotation velocity; (iii) we
find that the distribution function of the spin parameter $\lambda$ peaks at a
value of about 0.03, consistent with a no-major-merger scenario for the late
evolution of spiral galaxies.


title: Shear Waves and Giant Flare Oscillations from Soft Gamma-Ray Repeaters

abstract:
  Recent observations of giant flares from soft gamma-ray repeaters have
exhibited multiple 25-150 Hz oscillations. Frequencies in this range are
expected for toroidal shear waves in a neutron star (NS) crust, lending support
to Duncan's proposal that such modes may be excited in these events. This
motivates a reassessment of how these waves reflect the NS structure and what
role the magnetic field plays in setting their frequencies. We calculate the
eigenfrequencies and eigenfunctions of toroidal oscillations for a realistic NS
crust, including a vertical magnetic field at magnetar strengths
($B\sim10^{14}-10^{15} {\rm G}$). The lowest radial-order mode has a
red-shifted frequency of $\approx28 {\rm Hz}[l(l+1)/6]^{1/2}$, with the
prefactor depending on the NS's mass and radius, and its crust's depth and
composition. This mode is independent of the magnetic field for
$B\lesssim4\times10^{15} {\rm G}$, a limit much greater than the inferred
dipole magnetic fields for these objects. Though this is a good fit to the
observed oscillations, only rather loose constraints can be made for the NSs'
properties because all that can be fit is this prefactor (a single parameter).
Modes with shorter radial wavelengths are more sensitive to the magnetic field
starting at $B\sim2\times10^{14} {\rm G}$ and have higher frequencies (600-2000
Hz). The discovery of these modes, coupled with the oscillations observed thus
far, would provide a powerful probe to the NS crustal structure.


title:
Resolved Spectroscopy of M Dwarf/L Dwarf Binaries. I. DENIS
  J220002.05-303832.9AB

abstract:
  We present the discovery of the common proper motion M9 + L0 binary DENIS
J220002.05-303832.9AB, identified serendipitously with the SpeX near infrared
imager/spectrograph. Spectral types are derived from resolved near infrared
spectroscopy of the well-separated (1"09+/-0"06) components and comparison to
equivalent data for M and L dwarf spectral standards. Physical association is
deduced from the angular proximity of the sources, their common proper motion
and their similar spectrophotometric distances (35+/-2 pc). The estimated
distance of this pair implies a projected separation of 38+/-3 AU, wider than
typical separations for other M dwarf/L dwarf binaries, but consistent with the
maximum separation/total system mass trend previously identified by Burgasser
et al. (2003). We discuss the DENIS 2200-3038AB system in context with other
low mass binaries, and its role in studying dust formation processes and
activity trends across the transition between the M and L dwarf spectral
classes.


title:
SDSS J042348.57-041403.5AB: A Brown Dwarf Binary Straddling the L/T
  Transition

abstract:
  We present the discovery of SDSS J042348.57-041403.5 as a closely-separated
(0"16) brown dwarf binary, resolved by the Hubble Space Telescope Near Infrared
Camera and Multi-Object Spectrometer. Physical association is deduced from the
angular proximity of the components and constraints on their common proper
motion. SDSS0423-0414AB appears to be composed of two brown dwarfs with
spectral types L6+/-1 and T2+/-1. Hence, this system straddles the transition
between L dwarfs and T dwarfs, a unique evolutionary phase of brown dwarfs
characterized by substantial shifts in spectral morphology over an apparently
narrow effective temperature range. Binarity explains a number of unusual
properties of SDSS 0423-0414, including its overluminosity and high effective
temperature compared to other early-type T dwarfs, and possibly its conflicting
spectral classifications (L7.5 in the optical, T0 in the near infrared). The
relatively short estimated orbital period of this system (~15-20 yr) and the
presence of Li I absorption in its combined light spectrum make it an ideal
target for both resolved spectroscopy and dynamical mass measurements. SDSS
0423-0414AB joins a growing list of late-L/early-T dwarf binaries, the high
percentage of which (~50%) may provide a natural explanation for observed
peculiarities across the L/T transition.


title: Detection of a Hot Binary Companion of $\eta$ Carinae

abstract:
  We report the detection of a hot companion of $\eta$ Carinae using high
resolution spectra (905 - 1180 \AA) obtained with the Far Ultraviolet
Spectroscopic Explorer (\fuse) satellite. Observations were obtained at two
epochs of the 2024-day orbit: 2003 June during ingress to the 2003.5 X-ray
eclipse and 2004 April several months after egress. These data show that
essentially all the far-UV flux from \etacar shortward of \lya disappeared at
least two days before the start of the X-ray eclipse (2003 June 29), implying
that the hot companion, \etaB, was also eclipsed by the dense wind or extended
atmosphere of \etaA. Analysis of the far-UV spectrum shows that \etaB is a
luminous hot star. The \nii \wll1084-1086 emission feature suggests that it may
be nitrogen-rich. The observed far-UV flux levels and spectral features,
combined with the timing of their disappearance, is consistent with \etacar\
being a massive binary system.


title: New constraint on the cosmological background of relativistic particles

abstract:
  We have derived new bounds on the relativistic energy density in the Universe
from cosmic microwave background (CMB), large scale structure (LSS), and type
Ia supernova (SNI-a) observations. In terms of the effective number of neutrino
species a bound of N_\nu = 4.2^{+1.2}_{-1.7} is derived at 95% confidence. This
bound is significantly stronger than previous determinations, mainly due to
inclusion of new CMB and SNI-a observations. The absence of a cosmological
neutrino background (N_\nu = 0) is now excluded at 5.4 \sigma. The value of
N_\nu is compatible with the value derived from big bang nucleosynthesis
considerations, marking one of the most remarkable successes of the standard
cosmological model. In terms of the cosmological helium abundance, the CMB,
LSS, and SNI-a observations predict a value of 0.240 < Y < 0.281.


title:
The Robustness of Dark Matter Density Profiles in Dissipationless
  Mergers

abstract:
  We present a comprehensive series of dissipationless N-body simulations to
investigate the evolution of density distribution in equal-mass mergers between
dark matter (DM) halos and multicomponent galaxies. The DM halo models are
constructed with various asymptotic power-law indices ranging from steep cusps
to core-like profiles and the structural properties of the galaxy models are
motivated by the LCDM paradigm of structure formation. The adopted force
resolution allows robust density profile estimates in the inner ~1% of the
virial radii of the simulated systems. We demonstrate that the central slopes
and overall shapes of the remnant density profiles are virtually identical to
those of the initial systems suggesting that the remnants retain a remarkable
memory of the density structure of their progenitors, despite the relaxation
that accompanies merger activity. We also find that halo concentrations remain
approximately constant through hierarchical merging involving identical systems
and show that remnants contain significant fractions of their bound mass well
beyond their formal virial radii. These conclusions hold for a wide variety of
initial asymptotic density slopes, orbital energies, and encounter
configurations, including sequences of consecutive merger events, simultaneous
mergers of severals ystems, and mergers of halos with embedded cold baryonic
components in the form of disks, spheroids, or both. As an immediate
consequence, the net effect of gas cooling, which contracts and steepens the
inner density profiles of DM halos, should be preserved through a period of
dissipationless major merging. Our results imply that the characteristic
universal shape of DM density profiles may be set early in the evolution of
halos.


title: The Origin of the Binary Pulsar J0737-3039

abstract:
  It is generally accepted that neutron stars form in core collapse events that
are accompanied by a supernovae (types II or Ib or Ic). Typical progenitors
are, therefore, larger than $\sim 2.1 \Ms$. We suggest \cite{PS04,PS05} that
the binary pulsar J0737-3039 provides evidence for a new formation channel:
collapse of a light progenitor. This binary pulsar J0737-3039 has several
remarkable features including among others: a very tight orbit with a Keplerian
velocity of ~600km/sec, a low eccentricity, and a location ~50pc from the
Galactic plane implying that the system has, at high likelihood, a small
(compared to Keplerian) center of mass velocity. A significant mass loss during
the formation of the second pulsar would have lead either to an eccentric orbit
or to a large center of mass velocity or to both. Therefore, we can set a
strong upper limit on the progenitor's mass. A progenitor more massive than
1.9$\Ms$ is ruled out (at 97% confidence). The kinematically favored option is
of a progenitor mass around 1.45$\Ms$. Recent evidence for a rather low
velocity proper motion supports this prediction and decreases the likelihood of
the standard (high mass progenitor) scenario. Lack of variations in the pulses'
profiles (which indicate no significant geodetic precession) provides further
support for the no kick and low progenitor mass formation scenario.


title: Sm Transition Probabilities and Abundances

abstract:
  Radiative lifetimes, accurate to +/- 5%, have been measured for 212
odd-parity levels of Sm II using laser-induced fluorescence. The lifetimes are
combined with branching fractions measured using Fourier-transform spectrometry
to determine transition probabilities for more than 900 lines of Sm II. This
work is the largest-scale laboratory study to date of Sm II transition
probabilities using modern methods. This improved data set has been used to
determine a new solar photospheric Sm abundance, log epsilon = 1.00 +/- 0.03,
from 26 lines. The spectra of three very metal-poor, neutron-capture-rich stars
also have been analyzed, employing between 55 and 72 Sm II lines per star. The
abundance ratios of Sm relative to other rare earth elements in these stars are
in agreement, and are consistent with ratios expected from rapid
neutron-capture nucleosynthesis (the r-process).


title:
On the fine structure of the sunspot penumbrae. III The vertical
  extension of penumbral filaments

abstract:
  In this paper we study the fine structure of the penumbra as inferred from
the uncombed model (flux tube embedded in a magnetic surrounding) when applied
to penumbral spectropolarimetric data from the neutral iron lines at 6300 \AA.
The inversion infers very similar radial dependences in the physical quantities
(LOS velocity, magnetic field strength etc) as those obtained from the
inversion of the Fe I 1.56 $\mu$m lines. In addition, the large Stokes $V$ area
asymmetry exhibited by the visible lines helps to constrain the size of the
penumbral flux tubes. As we demonstrate here, the uncombed model is able to
reproduce the area asymmetry with striking accuracy, returning flux tubes as
thick as 100-300 kilometers in the vertical direction, in good agreement with
previous investigations.


title: The Cosmic Infrared Background Experiment

abstract:
  We are developing a rocket-borne instrument (the Cosmic Infrared Background
ExpeRiment, or CIBER) to search for signatures of primordial galaxy formation
in the cosmic near-infrared extra-galactic background. CIBER consists of a
wide-field two-color camera, a low-resolution absolute spectrometer, and a
high-resolution narrow-band imaging spectrometer. The cameras will search for
spatial fluctuations in the background on angular scales from 7 arcseconds to 2
degrees over a range of angular scales poorly covered by previous experiments.
CIBER will determine if the fluctuations reported by the IRTS arise from
first-light galaxies or have a local origin. In a short rocket flight CIBER has
sensitivity to probe fluctuations 100 times fainter than IRTS/DIRBE. By jointly
observing regions of the sky studied by Spitzer and ASTRO-F, CIBER will build a
multi-color view of the near-infrared background, accurately assessing the
contribution of local (z = 1-3) galaxies to the observed background
fluctuations, allowing a deep and comprehensive survey for first-light galaxy
background fluctuations. The low-resolution spectrometer will search for a
redshifted Lyman cutoff feature between 0.8 - 2.0 microns. The high-resolution
spectrometer will trace zodiacal light using the intensity of scattered
Fraunhofer lines, providing an independent measurement of the zodiacal emission
and a new check of DIRBE zodiacal dust models. The combination will
systematically search for the infrared excess background light reported in
near-infrared DIRBE/IRTS data, compared with the small excess reported at
optical wavelengths.


title: Gamma-Ray Polarimetry of Two X-Class Solar Flares

abstract:
  We have performed the first polarimetry of solar flare emission at gamma-ray
energies (0.2-1 MeV). These observations were performed with the Reuven Ramaty
High Energy Solar Spectroscopic Imager (RHESSI) for two large flares: the GOES
X4.8-class solar flare of 2002 July 23, and the X17-class flare of 2003 October
28. We have marginal polarization detections in both flares, at levels of 21%
+/- 9% and -11% +/- 5% respectively. These measurements significantly constrain
the levels and directions of solar flare gamma-ray polarization, and begin to
probe the underlying electron distributions.


title: Spectroscopy of QUEST RR Lyrae Variables: the new Virgo Stellar Stream

abstract:
  Eighteen RR Lyrae variables (RRLs) that lie in the "$12\fh 4$ clump"
identified by the QUEST survey have been observed spectroscopically to measure
their radial velocities and metal abundances. Ten blue horizontal branch (BHB)
stars identified by the Sloan Digital Sky Survey (SDSS) were added to this
sample. Six of the 9 stars in the densest region of the clump have a mean
radial velocity in the galactic rest frame ($V_{\rm gsr}$) of 99.8 and $\sigma$
= 17.3 ${\rm km s}^{-1}$, which is slightly smaller than the average error of
the measurements. The whole sample contains 8 RRLs and 5 BHB stars that have
values of $V_{\rm gsr}$ suggesting membership in this stream. For 7 of these
RRLs, the measurements of [Fe/H], which have an internal precision of 0.08 dex,
yield $<{\rm [Fe/H]}> = -1.86$ and $\sigma$ = 0.40. These values suggest that
the stream is a tidally disrupted dwarf spheroidal galaxy of low luminosity.
Photometry from the database of the SDSS indicates that this stream covers at
least 106 deg$^2$ of the sky in the constellation Virgo. The name Virgo Stellar
Stream is suggested.


title: Acceleration Mechanics in Relativistic Shocks by the Weibel Instability

abstract:
  Plasma instabilities (e.g., Buneman, Weibel and other two-stream
instabilities) created in collisionless shocks may be responsible for particle
(electron, positron, and ion) acceleration. Using a 3-D relativistic
electromagnetic particle (REMP) code, we have investigated long-term particle
acceleration associated with relativistic electron-ion or electron-positron jet
fronts propagating into an unmagnetized ambient electron-ion or
electron-positron plasma. These simulations have been performed with a longer
simulation system than our previous simulations in order to investigate the
nonlinear stage of the Weibel instability and its particle acceleration
mechanism. The current channels generated by the Weibel instability are
surrounded by toroidal magnetic fields and radial electric fields. This radial
electric field is quasi stationary and accelerates particles which are then
deflected by the magnetic field.


title: Mg isotope ratios in giant stars of the globular clusters M 13 and M 71

abstract:
  We present Mg isotope ratios in 4 red giants of the globular cluster M 13 and
1 red giant of the globular cluster M 71 based on spectra obtained with HDS on
the Subaru Telescope. We confirm earlier results by Shetrone that for M 13, the
ratio varies from (25+26)Mg/24Mg = 1 in stars with the highest Al abundance to
(25+26)Mg/24Mg = 0.2 in stars with the lowest Al abundance. However, we
separate the contributions of all three isotopes and find a spread in the ratio
24Mg:25Mg:26Mg with values ranging from 48:13:39 to 78:11:11. As in NGC 6752,
we find a positive correlation between 26Mg and Al, an anticorrelation between
24Mg and Al, and no correlation between 25Mg and Al. In M 71, our one star has
a ratio 70:13:17. For both clusters, the lowest ratios of 25Mg/24Mg and
26Mg/24Mg exceed those observed in field stars at the same metallicity, a
result also found in NGC 6752. The contribution of 25Mg to the total Mg
abundance is constant within a given cluster and between clusters with
25Mg/(24+25+26)Mg = 0.13. For M 13 and NGC 6752, the ranges of the Mg isotope
ratios are similar and both clusters show the same correlations between Al and
Mg isotopes suggesting that the same process is responsible for the abundance
variations in these clusters. While existing models fail to reproduce all the
observed abundances, we continue to favor the scenario in which two generations
of AGB stars produce the observed abundances. A first generation of metal-poor
AGB stars pollutes the entire cluster and is responsible for the large ratios
of 25Mg/24Mg and 26Mg/24Mg observed in cluster stars with compositions
identical to field stars at the same metallicity. Differing degrees of
pollution by a second generation of AGB stars of the same metallicity as the
cluster provides the star-to-star scatter in Mg isotope ratios.


title: Temperature and Dark Matter profiles of Galaxy Groups

abstract:
  The Chandra and XMM data for a sample of 19 relaxed groups/poor clusters,
covering the temperature range 1-3 keV and selected to have the best available
data, reveal a remarkable similarity in their temperature profile: cool cores
outside of which the temperatures reach a peak for radii less than 0.1 of the
virial radius and then decline. We fitted the derived mass profiles using an
NFW model, which provides a good fit to the data when accounting for the
central galaxy in the inner region. The concentration parameters and virial
masses are in the range c = 5-22 and M = 2 x 10^13 - 4 x 10^14 solar masses, in
general agreement with the concentrations found in numerical simulations.


title: The Deuterium, Oxygen, and Nitrogen Abundance Toward LSE 44

abstract:
  We present measurements of the column densities of interstellar DI, OI, NI,
and H2 made with FUSE, and of HI made with IUE toward the sdO star LSE 44, at a
distance of 554+/-66 pc. This target is among the seven most distant Galactic
sight lines for which these abundance ratios have been measured. The column
densities were estimated by profile fitting and curve of growth analyses. We
find D/H = (2.24 +1.39 -1.32)E-5, D/O = (1.99 +1.30 -0.67)E-2, D/N = (2.75
+1.19 -0.89)E-1, and O/H = (1.13 +0.96 -0.71)E-3 (2 sigma). Of the most distant
Galactic sight lines for which the deuterium abundance has been measured LSE 44
is one of the few with D/H higher than the Local Bubble value, but D/O toward
all these targets is below the Local Bubble value and more uniform than the D/H
distribution. (Abstract abridged.)


title:
Detectability of planetary rings around an extrasolar planet from
  reflected-light photometry

abstract:
  The next generation of high-contrast imaging instruments will provide the
first unresolved image of an extrasolar planet. While the emitted infrared
light from the planet in thermal equilibrium should show almost no phase
effect, the reflected visible light will vary with the orbital phase angle. We
study the photometric variation of the reflected light with orbital phase of a
ringed extrasolar planet. We show that a ring around an extrasolar planet, both
obviously unresolved, can be detected by its specific photometric signature.
  Keywords: Stars: planetary systems -- Planets: rings -- Extrasolar planet
characterization


title: The Bright Ages Survey. I. Imaging Data

abstract:
  This is the first paper in a series presenting and analyzing data for a
K-selected sample of galaxies collected in order to identify and study galaxies
at moderate to high redshift in rest-wavelength optical light. The sample
contains 842 objects over 6 separate fields covering 75.6 arcmin^2 down to
K=20-20.5. We combine the K-band with UBVRIzJH multi-band imaging, reaching
depths of R~26. Two of the fields studied also have deep HST WFPC2 imaging,
totaling more than 60 hours in the F300W, F450W, F606W, and F814W filters.
Using artificial galaxy modeling and extraction we measure 85% completeness
limits down to K=19.5-20, depending on the field examined. The derived K-band
number counts are in good agreement with previous studies. We find a density
for Extremely Red Objects(EROs; R-K>5) of 1.55+/-0.16 arcmin^{-2} for K<19.7,
dominated by the 1714+5015 field (centered on 53w002), with an ERO number
density more than 3 times that of the other sample fields. If we exclude the
counts for 1714+5015, our density is 0.95+/- 0.14 arcmin. Both ERO densities
are consistent with previous measurements due to the significant known cosmic
variance of these red sources.Keck spectroscopic redshifts were obtained for 18
of the EROs, all but one of which are emission galaxies. None of the EROs in
the 1714+5015 field for which we obtained spectroscopic redshifts are
associated with the known z=2.39 over-density, although there are three
different galaxy redshift pairs (z=0.90, z=1.03, z=1.22).


title:
Fundamental properties of pre-main sequence stars in young, southern
  star forming regions: metallicities

abstract:
  Aims: The primary motivation for this project is to search for metal-rich
star forming regions, in which, stars of super-solar metallicity will be
created, as hopefully, will be extra-solar planets orbiting them !
  Results: We find (pre-main sequence) model-dependent isochronal ages of the
Lupus, Chamaeleon and CrA targets to be $9.1 \pm 2.1$ Myr, $4.5 \pm 1.6$ Myr
and $9.0 \pm 3.9$ Myr respectively. The majority of the stars have Li I 6707.8A
equivalent widths similar to, or above those of, their similar mass Pleiades
counterparts, confirming their youthfulness. Most stars are kinematic members,
either single or binary, of their regions. We find a mean radial velocity for
objects in the Lupus cloud to be ${\bar {RV}}=+2.6 \pm 1.8$ km s$^{-1}$, for
the Chamaeleon I & II clouds, ${\bar {RV}}=+12.8 \pm 3.6$ km s$^{-1}$ whereas
for the CrA cloud, we find ${\bar {RV}}=-1.1 \pm 0.5$ km s$^{-1}$.
  All stars are coronally and chromospherically active, exhibiting X-ray and
H$\alpha$ emission levels marginally less, approximately equal or superior to
that of their older IC 2602/2391 and/or Pleiades counterparts. All bar three of
the targets show little or no signature of accretion from a circumstellar
environment, according to their positions in a J$-$K/H$-$K$^{'}$ diagram.
  We have performed a metallicity analysis for 5 stars in Chamaeleon, 4 stars
in Lupus and 3 stars in the CrA star forming regions. These results show that
all three regions are slightly metal-poor, with marginally sub-solar
metallicities, with $<$[Fe/H]$> = -0.11 \pm 0.14$, $-0.10 \pm 0.04$ & $-0.04
\pm 0.05$ respectively.


title:
High-contrast Imaging from Space: Speckle Nulling in a Low Aberration
  Regime

abstract:
  High-contrast imaging from space must overcome two major noise sources to
successfully detect a terrestrial planet angularly close to its parent star:
photon noise from diffracted star light, and speckle noise from star light
scattered by instrumentally-generated wavefront perturbation. Coronagraphs
tackle only the photon noise contribution by reducing diffracted star light at
the location of a planet. Speckle noise should be addressed with
adaptative-optics systems. Following the tracks of Malbet, Yu and Shao (1995),
we develop in this paper two analytical methods for wavefront sensing and
control that aims at creating dark holes, i.e. areas of the image plane cleared
out of speckles, assuming an ideal coronagraph and small aberrations. The first
method, speckle field nulling, is a fast FFT-based algorithm that requires the
deformable-mirror influence functions to have identical shapes. The second
method, speckle energy minimization, is more general and provides the optimal
deformable mirror shape via matrix inversion. With a NxN deformable mirror, the
size of matrix to be inverted is either N^2xN^2 in the general case, or only
NxN if influence functions can be written as the tensor product of two
one-dimensional functions. Moreover, speckle energy minimization makes it
possible to trade off some of the dark hole area against an improved contrast.
For both methods, complex wavefront aberrations (amplitude and phase) are
measured using just three images taken with the science camera (no dedicated
wavefront sensing channel is used), therefore there are no non-common path
errors. We assess the theoretical performance of both methods with numerical
simulations, and find that these speckle nulling techniques should be able to
improve the contrast by several orders of magnitude.


title: w and w' of Scalar Field Models of Dark Energy

abstract:
  Important observables to reveal the nature of dark energy are the equation of
state $w$ and its time derivative in units of the Hubble time $w'$. Recently,
it is shown that the simplest scalar field models of dark energy (quintessence)
occupy rather narrow regions in the $w-w'$ plane. We extend the $w-w'$ plane to
$w<-1$ and derive bounds on $w'$ as a function of $w$ for tracker phantom dark
energy. We also derive bounds on tracker k-essence.


title:
An Imaging Study of the Globular Cluster Systems of NGC 1407 and NGC
  1400

abstract:
  We present wide-field Keck telescope imaging of the globular cluster (GC)
systems around NGC 1407 and NGC 1400 in the Eridanus galaxy cloud. This is
complemented by Hubble Space Telescope images from the Advanced Camera for
Surveys of NGC 1407 and Wide Field and Planetary Camera 2 images of NGC 1400.
We clearly detect bimodality in the GC colour distribution of NGC 1407. The
blue GC subpopulation has a mean colour of B-I = 1.61 and a relative
contribution of around 40%, whereas the red subpopulation with B-I = 2.06
contributes 60% to the overall GC system. Assuming old ages, this corresponds
to [Fe/H] = -1.45 and -0.19. Both subpopulations are intrinsically broad in
colour (indicating a range in ages and/or metallicities), with the red
subpopulation being broader than the blue. The GC colour distribution for NGC
1400 is less clear cut than for NGC 1407, however, we also find evidence for a
bimodal distribution. We find the NGC 1407 red GCs to be 20% smaller in size
than the blue ones. We find both GC systems to possess a GC surface density
distribution which is largely constant in these inner galaxy regions. We fit
isothermal-like profiles and derive GC system core radii of 9.4 kpc for NGC
1407 and 5.8 kpc for NGC 1400. For NGC 1407 we are able to separate the surface
density distribution into blue and red subpopulations, giving 17.8 and 7.6 kpc
respectively. Outside this central region, the radial profile of the GC surface
density is similar to that of the galaxy light for NGC 1407 but it is flatter
for NGC 1400. A fit to the GC luminosity function gives a distance modulus of
31.6, which is in good agreement with distances based on the Faber-Jackson
relation and the Virgo infall corrected velocity.


title: High Resolution Mapping of Interstellar Clouds by Near--IR Scattering

abstract:
  We discuss the possibility of mapping interstellar clouds at unprecedentedly
high spatial resolution by means of near-IR imaging of their scattered light.
We calculate the scattering of the interstellar radiation field by a cloud
model obtained from the simulation of a supersonic turbulent flow. Synthetic
maps of scattered light are computed in the J, H and K bands and are found to
allow an accurate estimate of column density, in the range of visual extinction
between 1 and 20 magnitudes. We provide a formalism to convert the intensity of
scattered light at these near-IR bands into a total gas column density. We also
show that this new method of mapping interstellar clouds is within the
capability of existing near-IR facilities, which can achieve a spatial
resolution of up to ~ 0.1 arcsec. This opens new perspectives in the study of
interstellar dust and gas structure on very small scales. The validity of the
method has been recently demonstrated by the extraordinary images of the
Perseus region obtained by Foster & Goodman (2005), which motivated this
investigation.


title: Early Stage of Galaxy Formation

abstract:
  We discuss on the early stage of galaxy formation based on recent deep
surveys for very high-redshift galaxies, mostly beyond redshift of 6. These
galaxies are observed to be strong Lyman$\alpha$ emitters, indicating bursts of
massive star formation in them. The fraction of such star-forming system
appears to increase with increasing redshift. On the other hand, the star
formation rate density derived from Lyman$\alpha$ emitters tends to decrease
with increasing redshift. It is thus suggested that the major epoch of initial
starbursts may occur around $z \sim$ 6 -- 7. In order to understand the early
stage of galaxy formation, new surveys for galaxies beyond redshift of 7 will
be important in near future.