title: Black hole hunting in the Andromeda Galaxy

abstract:
  We present a new technique for identifying stellar mass black holes in low
mass X-ray binaries (LMXBs), and apply it to XMM-Newton observations of M31. We
examine X-ray time series variability seeking power density spectra (PDS)
typical of LMXBs accreting at a low accretion rate (which we refer to as Type A
PDS); these are very similar for black hole and neutron star LMXBs. Galactic
neutron star LMXBs exhibit Type A PDS at low luminosities (~10^36--10^37 erg/s)
while black hole LMXBs can exhibit them at luminosities >10^38 erg/s. We
propose that Type A PDS are confined to luminosities below a critical fraction
of the Eddington limit, $l_c$ that is constant for all LMXBs; we have examined
asample of black hole and neutron star LMXBs and find they are all consistent
with $l_c$ = 0.10+/-0.04 in the 0.3--10 keV band. We present luminosity and PDS
data from 167 observations of X-ray binaries in M31 that provide strong support
for our hypothesis. Since the theoretical maximum mass for a neutron star is
\~3.1 M_Sun, we therefore assert that any LMXB that exhibits a Type A PDS at a
0.3--10 keV luminosity greater than 4 x 10^37 erg/s is likely to contain a
black hole primary. We have found eleven new black hole candidates in M31 using
this method. We focus on XMM-Newton observations of RX J0042.4+4112, an X-ray
source in M31 and find the mass of the primary to be 7+/-2 M_Sun, if our
assumptions are correct. Furthermore, RX J0042.4+4112 is consistently bright in
\~40 observations made over 23 years, and is likely to be a persistently bright
LMXB; by contrast all known Galactic black hole LMXBs are transient. Hence our
method may be used to find black holes in known, persistently bright Galactic
LMXBs and also in LMXBs in other galaxies.


title: Gas near active galactic nuclei: A search for the 4.7micron CO band

abstract:
  In order to constrain the properties of dense and warm gas around active
galactic nuclei, we have searched Infrared Space Observatory spectra of local
active galactic nuclei for the signature of the 4.7micron fundamental
ro-vibrational band of carbon monoxide. Low resolution spectra of 31 AGN put
upper limits on the presence of wide absorption bands corresponding to
absorption by large columns of warm and dense gas against the nuclear dust
continuum. High resolution (R~2500) spectra of NGC 1068 detect no significant
absorption or emission in individual lines, to a 3sigma limit of 7% of the
continuum. The limits set on CO absorption in local AGN are much lower than the
recent Spitzer Space Telescope detection of strong CO absorption by dense and
warm gas in the obscured ultraluminous infrared galaxy IRAS F00183-7111,
despite evidence for dense material on parsec scales near an AGN in both types
of objects. This suggests that such deep absorptions are not intimately related
to the obscuring `torus' material invoked in local AGN, but rather are a
signature of the peculiar conditions in the circumnuclear region of highly
obscured infrared galaxies like IRAS F00183-7111. They may reflect fully
covered rather than torus geometries.


title:
The intermediate-redshift galaxy cluster CL 0048-2942. Stellar
  populations

abstract:
  We present a detailed study of the cluster CL 0048-2942, located at z~0.64,
based on a photometric and spectroscopic catalogue of 54 galaxies in a 5 x 5
square arcmin region centred in that cluster. Of these, 23 galaxies were found
to belong to the cluster. Based on this sample, the line-of-sight velocity
dispersion of the cluster is approximately 680 +- 140 km/s. We have performed
stellar population synthesis in the cluster members as well as in the field
galaxies of the sample and found that there are population gradients in the
cluster with central galaxies hosting mainly intermediate/old populations
whereas galaxies in the cluster outskirts show clearly an increase of younger
populations, meaning that star formation is predominantly taking place in the
outer regions of the cluster. In a general way, field galaxies seem to host
less evolved stellar populations than cluster members. In fact, in terms of
ages, young supergiant stars dominate the spectra of field galaxies whereas
cluster galaxies display a dominant number of old and intermediate age stars.
Following the work of other authors (e.g. Dressler et al. 1999) we have
estimated the percentage of K+A galaxies in our sample and found around 13% in
the cluster and 10% in the field. These values were estimated through means of
a new method, based on stellar population synthesis results, that takes into
account all possible absorption features in the spectrum and thus makes optimal
use of the data.


title: Compact radio cores: from the first black holes to the last

abstract:
  One of the clearest signs of black hole activity is the presence of a compact
radio core in the nuclei of galaxies. With the Square Kilometer Array (SKA)
these cores can be used to study the evolution of black holes throughout the
universe and even to detect the very first generation of supermassive black
holes. We start by introducing some of the basic properties of compact radio
cores and how they scale with accretion power. The relative contribution of
jets and radio cores to the Spectral Energy Distribution (SED) is strongest in
sub-Eddington black holes but also present in the most luminous objects. Radio
and X-rays are correlated as a function of black hole mass such that the most
massive black holes are most suited for radio detections. We present a radio
core luminosity function for the present universe down to the least luminous
AGN. The SKA will essentially detect all dormant black holes in the local
universe, such as that in our Milky Way, out to several tens of Megaparsecs. It
will also be able to see black holes in the making at redshifts z>10 for black
hole masses larger than 10^7 M_sun. Finally, we suggest that the first
generation of black holes may have jets that are frustrated in their dense
environment and thus appear as Gigahertz-Peaked-Spectrum (GPS) sources. Since
their intrinsic size and peak frequency are related and angular size and
frequency scale differently with redshift, there is a unique region in
parameter space that should be occupied by emerging black holes in the epoch of
reionization. This can be well probed by radio-only methods with the SKA.
(abridged)


title: A radial velocity search for p-modes in betaVir

abstract:
  Spectroscopic high-resolution observations were performed with fiber-fed
cross-dispersed echelle spectrographs in order to measure the fluctuations in
radial velocities of a sample of bright stars that are likely to undergo
solar-like oscillations. Here we report the results for beta Vir (HR4540) from
two observing runs carried out in February 2002 with FEROS at the ESO 1.52 m
telescope in La Silla (Chile) and ELODIE spectrograph at 1.93 OHP telescope
(Observatoire de Haute Provence, France). The analysis of the time series of
Doppler shifts from both sites has revealed the presence of an excess power
around 1.7 mHz. We discuss the interpretation of this data set in terms of
possible p-mode oscillations.


title:
The statistical nature of the second order corrections to the thermal
  SZE

abstract:
  This paper shows that the accepted expressions for the second order
corrections in the parameter $z$ to the thermal Sunyaev-Zel'dovich effect can
be accurately reproduced by a simple convolution integral approach. This
representation allows to separate the second order SZE corrections into two
type of components. One associated to a single line broadening, directly
related to the even derivative terms present in the distortion intensity curve,
while the other is related to a frequency shift, which is in turn related to
the first derivative term.


title:
Global Characteristics of X-Ray Flashes and X-Ray-Rich GRBs Observed by
  HETE-2

abstract:
  We describe and discuss the global properties of 45 gamma-ray bursts (GRBs)
observed by HETE-2 during the first three years of its mission, focusing on the
properties of X-Ray Flashes (XRFs) and X-ray-rich GRBs (XRRs). We find that the
numbers of XRFs, XRRs, and GRBs are comparable. We find that the durations and
the sky distributions of XRFs and XRRs are similar to those of GRBs. We also
find that the spectral properties of XRFs and XRRs are similar to those of
GRBs, except that the values of the peak energy $E^{\rm obs}_{\rm peak}$ of the
burst spectrum in $\nu F_\nu$, the peak energy flux $\Fp$, and the energy
fluence $S_E$ of XRFs are much smaller -- and those of XRRs are smaller -- than
those of GRBs. Finally, we find that the distributions of all three kinds of
bursts form a continuum in the [$S_E$(2-30 keV),$S_E$(30-400) keV]-plane, the
[$S_E$(2-400 keV), $E_{\rm peak}$]-plane, and the [$F_{\rm peak}$(50-300 keV),
$E_{\rm peak}$]-plane. These results provide strong evidence that all three
kinds of bursts arise from the same phenomenon.


title:
Distant source image motion due to gravitational field of the Galaxy
  stars

abstract:
  Gravitational field of stars of the Galaxy causes additional motions of
images of extragalactic sources. For typical realization of stars this results
in a small rotation of extragalactic reference frame in the direction of
Galactic rotation. We estimate angular velocity of corresponding image motion
and show that it is different in case of discrete and continuous matter
distribution in the Galaxy.


title: Classifying the zoo of ultraluminous X-ray sources

abstract:
  Ultraluminous X-ray sources (ULXs) are likely to include different physical
types of objects. We discuss some possible subclasses, reviewing the properties
of a sample of ULXs recently observed by Chandra and XMM-Newton. Sources with
an isotropic X-ray luminosity up to a few times 10^{39} erg/s are consistent
with ``normal'' stellar-mass X-ray binaries (mostly high-mass X-ray binaries in
star-forming regions). Higher black hole (BH) masses (~ 50-100 M_sun) may be
the end product of massive stellar evolution in peculiar environments: they may
explain ULXs with luminosities ~ 1-2 x 10^{40} erg/s. Only a handful of ULXs
require a true intermediate-mass BH (M >~ 500 M_sun). Finally, a small subclass
of ULXs shows flaring or rapid variability in its power-law spectral component.


title: The current status of observational cosmology

abstract:
  Observational cosmology has indeed made very rapid progress in recent years.
The ability to quantify the universe has largely improved due to observational
constraints coming from structure formation. The transition to precision
cosmology has been spearheaded by measurements of the anisotropy in the cosmic
microwave background (CMB) over the past decade. Observations of the large
scale structure in the distribution of galaxies, high red-shift supernova, have
provided the required complementary information. We review the current status
of cosmological parameter estimates from joint analysis of CMB anisotropy and
large scale structure (LSS) data. We also sound a note of caution on
overstating the successes achieved thus far.


title: Strong Lensing Analysis of A1689 from Deep Advanced Camera Images

abstract:
  We analyse deep multi-colour Advanced Camera images of the largest known
gravitational lens, A1689. Radial and tangential arcs delineate the critical
curves in unprecedented detail and many small counter-images are found near the
center of mass. We construct a flexible light deflection field to predict the
appearance and positions of counter-images. The model is refined as new
counter-images are identified and incorporated to improve the model, yielding a
total of 106 images of 30 multiply lensed background galaxies, spanning a wide
redshift range, 1.0$<$z$<$5.5. The resulting mass map is more circular in
projection than the clumpy distribution of cluster galaxies and the light is
more concentrated than the mass within $r<50kpc/h$. The projected mass profile
flattens steadily towards the center with a shallow mean slope of
$d\log\Sigma/d\log r \simeq -0.55\pm0.1$, over the observed range,
r$<250kpc/h$, matching well an NFW profile, but with a relatively high
concentration, $C_{vir}=8.2^{+2.1}_{-1.8}$. A softened isothermal profile
($r_{core}=20\pm2$\arcs) is not conclusively excluded, illustrating that
lensing constrains only projected quantities. Regarding cosmology, we clearly
detect the purely geometric increase of bend-angles with redshift. The
dependence on the cosmological parameters is weak due to the proximity of
A1689, $z=0.18$, constraining the locus, $\Omega_M+\Omega_{\Lambda} \leq 1.2$.
This consistency with standard cosmology provides independent support for our
model, because the redshift information is not required to derive an accurate
mass map. Similarly, the relative fluxes of the multiple images are reproduced
well by our best fitting lens model.


title:
The VIMOS VLT Deep Survey - First epoch VVDS-Deep survey: 11564 spectra
  with 17.5<=IAB<=24, and the redshift distribution over 0< z <=5

abstract:
  This paper presents the ``First Epoch'' sample from the VIMOS VLT Deep Survey
(VVDS). The VVDS goals, observations, data reduction with VIPGI, and redshift
measurement with KBRED are discussed. Data have been obtained with the VIsible
Multi Object Spectrograph (VIMOS) on the ESO-VLT UT3, allowing to observe ~600
slits simultaneously at R~230. A total of 11564 objects have been observed in
the VVDS-02h and VVDS-CDFS Deep fields over a total area of 0.61deg^2, selected
solely on the basis of apparent magnitude 17.5 <=I_{AB} <=24. The VVDS covers
the redshift range 0 < z <= 5. It is successfully going through the ``redshift
desert'' 1.5<z<2.2, while the range 2.2<z<2.7 remains of difficult access
because of the VVDS wavelength coverage.A total of 9677 galaxies have a
redshift measurement, 836 are stars, 90 are AGNs, and a redshift could not be
measured for 961 objects. There are 1065 galaxies with a measured redshift
z>1.4. The survey reaches a redshift measurement completeness of 78% overall
(93% including less reliable objects), with a spatial sampling of the
population of galaxies of 25% and ~30% in the VVDS-02h and VVDS-CDFS. The
redshift accuracy measured from repeated observations with VIMOS and comparison
to other surveys is ~276km/s. From this sample we present for the first time
the redshift distribution of a magnitude limited spectroscopic sample down to
IAB=24. The redshift distribution has a median of z=0.62, z=0.65, z=0.70, and
z=0.76, for magnitude limited samples with IAB<=22.5, 23, 23.5, and 24. A high
redshift tail above redshift 2 and up to redshift 5 becomes readily apparent
for IAB>23.5, probing the bright star forming population of galaxies. This
sample provides an unprecedented dataset to study galaxy evolution over 90% of
the life of the universe


title:
The VIMOS-VLT Deep Survey: Evolution of the galaxy luminosity function
  up to z=2 in first epoch data

abstract:
  We investigate the evolution of the galaxy luminosity function from the
VIMOS-VLT Deep Survey (VVDS) from the present to z=2 in five (U, B, V, R and I)
rest-frame band-passes. We use the first epoch VVDS deep sample of 11,034
spectra selected at 17.5 <= I_{AB} <= 24.0, on which we apply the Algorithm for
Luminosity Function (ALF), described in this paper. We observe a substantial
evolution with redshift of the global luminosity functions in all bands. From
z=0.05 to z=2, we measure a brightening of the characteristic magnitude M*
included in the magnitude range 1.8-2.5, 1.7-2.4, 1.2-1.9, 1.1-1.8 and 1.0-1.6
in the U, B, V, R and I rest-frame bands, respectively. We confirm this
differential evolution of the luminosity function with rest-frame wavelength,
from the measurement of the comoving density of bright galaxies (M <
M*(z=0.1)). This density increases by a factor of around 2.6, 2.2, 1.8, 1.5,
1.5 between z=0.05 and z=1 in the U, B, V, R, I bands, respectively. We also
measure a possible steepening of the faint-end slope of the luminosity
functions, with \Delta\alpha ~ -0.3 between z=0.05 and z=1, similar in all
bands.


title:
The VIMOS VLT Deep Survey - The evolution of galaxy clustering to z=2
  from first epoch observations

abstract:
  This paper presents the evolution of the clustering of the main population of
galaxies from z=2.1 to z=0.2, from the first epoch VIMOS VLT Deep Survey
(VVDS), a magnitude limited sample with 17.5<=I_{AB}<=24. We have computed the
correlation functions \xi(r_p,\pi) and w_p(r_p), and the correlation length
r_0(z), for the VVDS-02h and VVDS-CDFS fields, for a total of 7155 galaxies in
a 0.61deg^2 area. We find that the correlation length in this sample stays
roughly constant from z=0.5 to z=1.1, with r_0(z)=2.5-2.8 h^{-1} Mpc
(comoving), for galaxies comparable in luminosity to the local 2dFGRS and SDSS
samples, indicating that the amplitude of the correlation function was ~2.5x
lower at z~1 than observed locally. The correlation length in our lowest
redshift bin z=[0.2,0.5] is r_0=2.4 h^{-1} Mpc, lower than for any other
population at the same redshift, indicating the low clustering of very low
luminosity galaxies, 1.5 magnitudes fainter than in the 2dFGRS or SDSS. The
correlation length is increasing to r_0~3.0 h^{-1} Mpc at higher redshifts
z=[1.3,2.1], as we are observing increasingly brighter galaxies, comparable to
galaxies with MB_AB=-20.5 locally. We compare our measurement to the DEEP2
measurements in the range z=[0.7,1.35] \citep{coil} on the population selected
applying the same magnitude and color selection criteria as in their survey,
and find comparable results. The slowly varying clustering of VVDS galaxies as
redshift increases is markedly different from the predicted evolution of the
clustering of dark matter, indicating that bright galaxies are already tracing
the large scale structures emerging from the dark matter distribution 9-10
billion years ago, a supporting evidence for a strong evolution of the galaxy
vs. dark matter bias.


title:
Hot subdwarfs from the ESO Supernova Ia Progenitor Survey - I.
  Atmospheric parameters and cool companions of sdB stars

abstract:
  We present the analysis of a high-resolution, high-quality sample of optical
spectra for 76 subdwarf B (sdB) stars from the ESO Supernova Ia Progenitor
Survey (SPY). Effective temperature, surface gravity, and photospheric helium
abundance are determined simultaneously by fitting the profiles of hydrogen and
helium lines using synthetic spectra calculated from LTE and NLTE model
atmospheres. We perform a detailed comparison of our measurements with
theoretical calculations, both for single star evolution and for binary
population synthesis models of close binary evolution. The luminosity evolution
given by the standard EHB evolutionary tracks from Dorman et al. (1993) shows
an overall agreement in shape with our observations, although a constant offset
in luminosity exists. The various simulation sets for binary formation channels
of sdB stars calculated by Han et al. (2003) are compared individually to our
data for testing our current understanding of sdB formation processes and the
physical effects involved. The best-matching sets manage to reproduce the
observed sdB distribution in the temperature-gravity-plane well. However, they
do not match the observed cumulative luminosity function, indicating that
theoretical improvement is necessary. We also investigate composite-spectrum
objects showing clear signatures of a cool companion with optical and infrared
photometry. These stars have cool main sequence companions of spectral types F
to K. Typical helium abundances of composite and non-composite sdB stars do not
differ.


title:
On the importance of local sources of radiation for quasar absorption
  line systems

abstract:
  A generic assumption of ionization models of quasar absorption systems is
that radiation from local sources is negligible compared with the cosmological
background. We test this assumption and find that it is unlikely to hold for
absorbers as rare as H I Lyman limit systems. Assuming that the absorption
systems are gas clouds centered on sources of radiation, we derive analytic
estimates for the cross-section weighted moments of the flux seen by the
absorbers, of the impact parameter, and of the luminosity of the central
source. In addition, we compute the corresponding medians numerically. For the
one class of absorbers for which the flux has been measured: damped Ly-alpha
systems at z~3, our prediction is in excellent agreement with the observations
if we assume that the absorption arises in clouds centered on Lyman-break
galaxies. Finally, we show that if Lyman-break galaxies dominate the UV
background at redshift 3, then consistency between observations of the UV
background, the UV luminosity density from galaxies, and the number density of
Lyman limit systems requires escape fractions of order 10 percent.


title:
The VIMOS VLT Deep Survey: Computing the two point correlation
  statistics and associated uncertainties

abstract:
  We are presenting in this paper a detailed account of the methods used to
compute the three-dimensional two-point galaxy correlation function in the
VIMOS-VLT deep survey (VVDS). We investigate how instrumental selection effects
and observational biases affect the measurements and identify the methods to
correct them. We quantify the accuracy of our correction method using an
ensemble of fifty mock galaxy surveys generated with the GalICS semi-analytic
model of galaxy formation which incorporate the same selection biases and
tiling strategy as the real data does. We demonstrate that we are able to
recover the real-space two-point correlation function xi(s) to an accuracy
better than 10% on scales larger than 1 h^{-1} Mpc, and of about 30% on scales
below 1 h^{-1} Mpc, with the sampling strategy used for the first epoch VVDS
data. The projected correlation function w_p(r_p) is recovered with an accuracy
better than 10% on all scales 0.1 <= r <= 10 h^{-1} Mpc. There is a tendency
for a small but systematic under-estimate of the correlation length derived
from w_p(r_p) of 6% on average, remaining after our correction process. The
large number of simulated surveys allows us to provide a reliable estimate of
the cosmic error on the measurements of the correlation length r_0, of about
15-20% for the first epoch VVDS observation (Le Fevre et al.2004,
astro-ph/0409133). The error estimation and measurement techniques outlined in
this paper are being used in several studies which investigate in detail the
clustering properties of galaxies in the VVDS data.


title:
A family of models of partially relaxed stellar systems I. Dynamical
  properties

abstract:
  [Abridged] Recently we have found that a family of models of partially
relaxed, anisotropic stellar systems, inspired earlier by studies of incomplete
violent relaxation, exhibits some interesting thermodynamic properties. Here we
present a systematic investigation of its dynamical characteristics, in order
to establish the basis for a detailed comparison with simulations of
collisionless collapse, planned for a separate paper. For a full comparison
with the observations of elliptical galaxies, the models should be extended to
allow for the presence a sizable dark halo and of significant rotation. In the
spherical limit, the family is characterized by two dimensionless parameters,
i.e. \Psi, measuring the depth of the galaxy potential, and \nu, defining the
form of a third global quantity Q, which is argued to be approximately
conserved during collisionless collapse (in addition to the total energy and
the total number of stars).


title: A Measurement of the UHECR Spectrum with the HiRes FADC Detector

abstract:
  We have measured the energy spectrum of ultra-high energy cosmic rays (UHECR)
with the HiRes FADC detector (HiRes-2) in monocular mode. A detailed Monte
Carlo simulation of the detector response to air showers has been used to
calculate the energy dependent acceptance of the air fluorescence detector. The
measured spectrum complements the measurement by the HiRes-1 detector down to
lower energies. Systematic effects of the assumed input spectrum and
composition on the aperture are presented, as well as systematics due to the
atmosphere.


title:
Measuring Changes in the Fundamental Constants with Redshifted Radio
  Absorption Lines

abstract:
  Strong evidence has recently emerged for a variation in the fine structure
constant, $\alpha\equiv e^2/\hbar c$, over the history of the Universe. This
was concluded from a detailed study of the relative positions of redshifted
optical quasar absorption spectra. However, {\it radio} absorption lines at
high redshift offer a much higher sensitivity to a cosmological change in
$\alpha$ than optical lines. Furthermore, through the comparison of various
radio transitions, \HI, OH and millimetre molecular (e.g. CO) lines, any
variations in the proton g-factor, $g_p$, and the ratio of electron/proton
masses, $\mu\equiv m_e/m_p$, may also be constrained. Presently, however,
systems exhibiting redshifted radio lines are rare with the bias being towards
those associated with optically selected QSOs. With its unprecedented
sensitivity, large bandwidth and wide field of view, the SKA will prove
paramount in surveying the sky for absorbers unbiased by dust extinction. This
is expected to yield whole new samples of \HI ~and OH rich systems, the latter
of which will prove a useful diagnostic in finding redshifted millimetre
absorbers. As well as uncovering many new systems through these blind surveys,
the SKA will enable the detection of \HI ~absorption in many more of the
present optical sample -- down to column densities of $\sim10^{17}$ \scm, or
$\gapp2$ orders of magnitude the sensitivity of the current limits. Armed with
these large samples together with the high spectral resolutions, available from
the purely radio comparisons, the SKA will provide statistically sound
measurements of the values of these fundamental constants in the early
Universe, thus providing a physical test of Grand Unified Theories.


title:
The Method of a Two-Point Conditional Column Density for Estimating the
  Fractal Dimension of the Galaxy Distribution

abstract:
  We suggest a new method for estimating the fractal dimension of the spatial
distribution of galaxies, the method of selected cylinders. We show the
capabilities of this method by constructing a two-point conditional column
density for galaxies with known redshifts from the LEDA database. The fractal
dimension of a sample of LEDA and EDR SDSS galaxies has been estimated to be D
= 2.1 for cylinder lengths of 200 Mpc. Amajor advantage of the suggested method
is that it allows scales comparable to the catalog depth to be analyzed for
galaxy surveys in the form of conical sectors and small fields in the sky.


title: On Kinetic Theory Viscosity in a Rotating Gas

abstract:
  Clarke and Pringle (2004) derived a proper viscosity formula in a rotating
gas by applying mean free path theory. We study their argument in detail and
show that their result can be derived with a much simpler calculational
procedure and physically clearer picture.


title:
The Influence of Black Hole Mass and Accretion Rate on the FRI/FRII
  Radio Galaxy Dichotomy

abstract:
  We use medium resolution optical spectra of 3CR radio galaxies to estimate
their black hole masses and accretion rates. Black hole masses are found from
central stellar velocity dispersions and accretion rates are derived from
narrow emission-line luminosities. The sample covers both Fanaroff-Riley (FR)
classes; the more powerful FRIIs and the less powerful FRIs. We find that FRIs
and FRIIs separate in diagrams of black hole mass versus radio luminosity and
narrow-line luminosity. This suggests that, at a given black hole mass, the
FRIIs accrete more efficiently, or accrete more matter, than FRIs.


title:
The distribution of two-dimensional eccentricity of Sunyaev-Zeldovich
  Effect and X-ray surface brightness profiles

abstract:
  With the triaxial density profile of dark matter halos and the corresponding
equilibrium gas distribution, we derive two-dimensional Sunyaev-Zeldovich (SZ)
effect and X-ray surface brightness profiles for clusters of galaxies. It is
found that the contour map of these observables can be well approximated by a
series of concentric ellipses with scale-dependent eccentricities. The
statistical distribution of their eccentricities (or equivalently axial ratios)
is analyzed by taking into account the orientation of clusters with respect to
the line of sight and the distribution of the axial ratios and the
concentration parameters of dark matter halos. For clusters of mass
$10^{13}h^{-1}{M}_{\odot}$ at redshift $z=0$, the axial ratio is peaked at
$\eta \sim 0.9$ for both SZ and X-ray profiles. For larger clusters, the
deviation from circular distributions is more apparent, with $\eta$ peaked at
$\eta \sim 0.85$ for $M=10^{15}h^{-1}{M}_{\odot}$. To be more close to
observations, we further study the axial-ratio distribution for mass-limited
cluster samples with the number distribution of clusters at different redshifts
described by a modified Press-Schechter model. For a mass limit of value
$M_{lim}=10^{14}h^{-1}{M}_{\odot}$, the average axial ratio is $<\eta > \sim
0.84$ with a tail extended to $\eta \sim 0.6$. With fast advance of high
quality imaging observations of both SZ effect and X-ray emissions, our
analyses provide a useful way to probe cluster halo profiles and therefore to
test theoretical halo-formation models.


title: Models of Stellar structure for asteroseismology

abstract:
  Among the problems still open in the study of stellar structure, we discuss
in particular some issues related to the study of convection. We have recently
built up complete stellar models, adopting a consistent formulation of
convection both in the non gray atmosphere and in the interior, to be used for
non adiabatic pulsational analysis, and discuss in some details two problems
which have been clarified by these models: the physical interpretation of one
of the main sequence "Boehm-Vitense gaps", and the necessity of parametrizing
pre main sequence convection differently from the main sequence convection. We
also report preliminary results of the application to the solar model of the
non--local turbulence equations by Canuto and Dubovikov (1998) in the
down-gradient approximation.


title: Molecular absorption in Cen A on VLBI scales

abstract:
  Centaurus A, the nearest AGN shows molecular absorption in the millimeter and
radio regime. By observing the absorption with VLBI, we try to constrain the
distribution of the gas, in particular whether it resides in the circumnuclear
region. Analysis of VLBA observations in four OH and two H2CO transitions is
presented here, as well as molecular excitation models parameterized with
distance from the AGN. We conclude that the gas is most likely associated with
the tilted molecular ring structure observed before in molecular emission and
IR continuum. The formaldehyde absorption shows small scale absorption which
requires a different distribution than the hydroxyl.


title: Mass Loss Timescale of Star Clusters in External Tidal Field

abstract:
  We investigate evolution of star clusters in external tidal field by means of
$N$-body simulations. We followed seven sets of cluster models whose central
concentration and strength of the tidal field are different. We found that the
mass loss timescale due to escape of stars, $t_{mloss}$, and its dependence on
the two-body relaxation timescale, $t_{rh,i}$, are determined by the strength
of the tidal field. The logarithmic slope [$= dln(t_{mloss})/dln(t_{rh,i})$]
approaches to near unity for the cluster models in weaker tidal field. The
timescale and the dependence are almost independent of the central
concentration for clusters in the tidal field of the same strength. In our
results, the scaling found by Baumgardt (2001) can be seen only in the cluster
models with moderately strong tidal field.


title: Why do some spotted stars become bluer as they become fainter?

abstract:
  Chromospherically active, spotted stars generally become redder as well as
fainter when large starspots rotate into view on the stellar disc. However, the
RS CVn system UX Ari (a triple-lined system), becomes bluer as it gets fainter.
One possible explanation is that hot, bright facular regions accompany the
cool, dark photospheric spots of the active component. The bluer flux of the
hotter, inactive component does not appear to be sufficient to explain the
observed behaviour. We have begun a search for additional chromospherically
active stars with a similar relation between colour and brightness, to
investigate whether these relations can be explained in the same way. Our
results for V711 Tau are presented here, and we conclude that the faculae
explanation holds also in this case.


title:
Sample of minor merger of galaxies: Optical CCD surface photometry and
  HII region propertie

abstract:
  We present the results of the B, V and I photometry of eleven southern minor
mergers. The total apparent B magnitude, integrated B-V and V-I colours were
measured. We built B, V, and I equivalent profiles for each galaxy and
decomposed them into bulge and disk components when possible. From
H$\alpha$+N[II] images we have estimated the basic photometric parameters of
the HII regions, such as position, size, B-V and V-I colours, H$\alpha$+[NII]
luminosity and $EW(H\alpha+[NII])$ equivalent width. We found a linear
correlation between the luminosity ratios of the components and their ratio of
major diameters, leading to mass ratios between 0.04 $<$ $\cal M$ $_{secondary}
/ \cal M$ $_{primary}$ $<$ 0.2, suggesting indeed that our sample is formed by
minor mergers. Most of the HII regions and evolved star-forming regions of the
sample were formed between 3.6 to 13.7 Myr ago with an average of (6.3$\pm$0.7)
Myr. The HII region properties, luminosity, sizes and ages are similar in both
components. The HII regions have log(H$\alpha$+[NII]) luminosity between 38.6
and 41.7. The HII region luminosity function for the whole sample fits a power
law of index $\alpha$ = --1.33. The linear correlation between the luminosity
$\cal L$(H$\alpha$+[NII]) and the size of the HII regions has slope of
2.12$\pm$0.06. We found that the disk of the primary component is more luminous
than those of Lu's sample, while the disk of the secondary is smaller and
fainter.


title: Multidimensional analysis of X-ray variability of AGN

abstract:
  In this work we analyzed X-ray light curves of active galactic nucleus NGC
4051 obtained using Advanced CCD Imaging Spectrometer of Chandra satellite.
Taking into account mainly flaring behaviour of AGNs we have used wavelet
analysis for searching of short time lived events on light curves.


title:
Spectropolarimetry and Infrared Photometry of Magnetic White Dwarfs:
  Vacuum Polarization Effect or Magnetic CIA?

abstract:
  We present brief review of two probable physical mechanisms that can explain
the results of photometric and spectropolarimetric observations of magnetic
white dwarfs: vacuum polarization effect into a strong magnetic field and,
so-called, magnetic collision induced absorption (magnetic CIA). Both
mechanisms provide observed rotation of polarization ellipse and suppression of
spectral energy distributions. The results of spectropolarimetric observations
of magnetic white dwarfs made at Russian BTA-6m and the results of the near
infrared photometric observations with Russian-Italian AZT-24 telescope located
at Campo Imperatore are also presented.


title: HI Observations of an Ultra-Compact High-Velocity Cloud

abstract:
  We present HI observations of the compact high-velocity cloud HVC289+33+251
that was discovered by Putman et al. (2002). Observations with the 100-m
Effelsberg telescope demonstrate that this cloud is still unresolved by the 9'
beam of the Effelsberg telescope. The cloud shows a small line width of Delta
v_FWHM = 4.9 km/s providing an upper limit to the kinetic temperature of the HI
gas of T_k < 532 K. The total observed flux indicates an HI mass of M(HI) =
5.66 10^4 M_sun [d/150kpc]^2. Follow-up HI observations using the Australia
Telescope Compact Array (ATCA) resolve HVC289+33+251 into 5 condensations that
are embedded in a common HI envelope. The HVC shows a faint tail, indicating an
ongoing ram-pressure interaction with an ambient low-density medium. A FWHM
diameter of theta = 4.4 arcmin makes this HVC the by far most compact HVC known
till now. The observed parameters suggest that pressure stabilization by an
ambient medium is rather unlikely. At a distance of 150 kpc, the virial mass is
by a factor of 5.6 higher than the observed gas mass -- consistent with
HVC289+33+251 being one of the "missing" dark matter mini halos that were
predicted by cosmological LCDM simulations (e.g. Klypin et al. 1999; Moore et
al. 1999). Comparable clouds in other groups of galaxies or even around the
Milky Way are not detectable with the resolution and sensitivity of present
surveys.


title:
On the Origin of Radio Emission in the X-ray States of XTE J1650-500
  during the 2001-2002 Outburst

abstract:
  We report on simultaneous radio and X-ray observations of the black hole
candidate XTE J1650-500 during the course of its 2001-2002 outburst. The
scheduling of the observations allowed us to sample the properties of XTE
J1650-50 in different X-ray spectral states, namely the hard state, the steep
power-law state and the thermal dominant state, according to the recent
spectral classification of McClintock & Remillard. The hard state is consistent
with a compact jet dominating the spectral energy distribution at radio
frequencies; however, the current data suggest that its contribution as direct
synchrotron emission at higher energies may not be significant. In that case,
XTE J1650-50 may be dominated by Compton processes (either inverse
Comptonization of thermal disk photons and/or SSC from the base of the compact
jet) in the X-ray regime. We, surprisingly, detect a faint level of radio
emission in the thermal dominant state that may be consistent with the emission
of previously ejected material interacting with the interstellar medium,
similar (but on a smaller angular scale) to what was observed in XTE J1550-564
by Corbel and co-workers. Based on the properties of radio emission in the
steep power-law state of XTE J1650-50, and taking into account the behavior of
other black hole candidates (namely GX 339-4, XTE J1550-564, and XTE J1859+226)
while in the intermediate and steep power-law states, we are able to present a
general pattern of behavior for the origin of radio emission in these two
states that could be important for understanding the accretion-ejection
coupling very close to the black hole event horizon.


title: Relativistic Jets in the RXTE Era

abstract:
  Since the launch of the Rossi X-ray Timing Explorer in 1995 our understanding
of jetted outflows has significantly improved. Indeed, relativistic jets are
now believed to be a fairly ubiquitous property of accreting compact objects,
that are intimately coupled with the accretion history. In this review, we
summarize the observational connections in X-ray binaries between accretion
flows and relativistic outflows (especially the relation with the X-ray
states). We emphasize those aspects that have significantly benefited from the
RXTE experiment, including the role that jets could play at high energies. We
also review recent observations of large scale relativistic jets that could
point to their long term effects on the interstellar medium.


title: On the Unpulsed Radio Emission from J0737-3039

abstract:
  The double pulsar system J0737-3039 appears associated with a continuous
radio emission, nearly three times stronger than that of the two pulsars
together. If such an emission comes from a tranparent cloud its spatial extent
(> 10^13 cm) should be substantially larger than the orbital separation.
Assuming homogeneity and equipartition, the cloud magnetic field is 0.03 G and
the electron characteristic energy ~ 60 MeV. This is consistent with supposing
that relativistic electrons produced in the shock formed by the interaction of
the more luminous pulsar wind with the magnetosphere of the companion flow away
filling a larger volume. Alternatively, the unpulsed emission may directly come
from the bow shock if some kind of coherent mechanism is at work. Possible
observational signatures that can dicriminate between the two pictures are
shortly discussed.


title: The Solar--Stellar Connection

abstract:
  Stars have proven to be surprisingly prolific radio sources and the added
sensitivity of the Square Kilometer Array will lead to advances in many
directions. This chapter discusses prospects for studying the physics of
stellar atmospheres and stellar winds across the HR diagram.


title: The Complex Interstellar Na I Absorption toward h and Chi Persei

abstract:
  Recent high spatial and spectral resolution investigations of the diffuse
interstellar medium (ISM) have found significant evidence for small-scale
variations in the interstellar gas on scales less than or equal to 1 pc. To
better understand the nature of small-scale variations in the ISM, we have used
the KPNO WIYN Hydra multi-object spectrograph, which has a mapping advantage
over the single-axis, single-scale limitations of studies using high proper
motion stars and binary stars, to obtain moderate resolution (~12 km/s)
interstellar Na I D absorption spectra of 172 stars toward the double open
cluster h and Chi Persei. All of the sightlines toward the 150 stars with
spectra that reveal absorption from the Perseus spiral arm show different
interstellar Na I D absorption profiles in the Perseus arm gas. Additionally,
we have utilized the KPNO Coude Feed spectrograph to obtain high-resolution (~3
km/s) interstellar Na I D absorption spectra of 24 of the brighter stars toward
h and Chi Per. These spectra reveal an even greater complexity in the
interstellar Na I D absorption in the Perseus arm gas and show individual
components changing in number, velocity, and strength from sightline to
sightline. If each of these individual velocity components represents an
isolated cloud, then it would appear that the ISM of the Perseus arm gas
consists of many small clouds. Although the absorption profiles vary even on
the smallest scales probed by these high-resolution data (~30";~0.35pc), our
analysis reveals that some interstellar Na I D absorption components from
sightline to sightline are related, implying that the ISM toward h and Chi Per
is probably comprised of sheets of gas in which we detect variations due to
differences in the local physical conditions of the gas.


title:
Test results of a prototype designed to detect horizontal cosmic ray
  flux

abstract:
  In this paper we report test results from a prototype designed to detect
muons from horizontal air shower at large zenith angle,
  $86^{0}<\Theta<93^{0}$. To detect horizontal tracks and their directions we
select them according the muon vertical equivalent charge and we measure the
time of flight with a time resolution of 800 ps. Several measurements are
collected at different zenith angles. The background studies performed with two
modules show that the main source is due to tracks crossing the module at the
same time. The upper limit of background flux for a single twin module is
estimated to be $10^{-9} cm^{-2}$ $s^{-1}$ $sr^{-1} (90%CL)$. We estimated the
size of the surface array necessary to detect the shower flux of the order of
$10^{-9} cm^{-2}$ $yr^{-1}$ $sr^{-1}$ if originated by Tau Air-Showers
secondaries of GZK neutrino Tau below the horizons.


title: A Supergiants

abstract:
  A-type supergiants are primary targets for quantitative spectroscopy of
individual stars in nearby galaxies because of their intrinsic brightness. An
overview is given on the non-LTE techniques required for their analysis.
Applications concentrate on placing observational constraints on evolutionary
models for massive stars and their host galaxies by detailed abundance
analyses. Results from high-resolution studies of A-type supergiants in Local
Group galaxies and from intermediate-resolution multi-object spectroscopy of
supergiants far beyond the Local Group are summarised.


title: Parametrization of Dark Energy Equation of State

abstract:
  A comparative study of various parametrizations of the dark energy equation
of state $w(z)$ and its variation with the redshift is made. Astrophysical
constraints from 'integrated tracking' are laid down to test the physical
viability and cosmological compatibility of these parametrizations. A critical
evaluation of the 4-index Hannestad parametrization is done. It is found to be
simple and transparent in probing the evolution of the dark energy during the
expansion history of the universe but it does not satisfy the BBN constraint on
the dark energy density parameter for the best fit values; however it looks
more compatible with the observations in the extended parameter space with $w<<
-1$.


title: Voids in a $\Lambda$CDM Universe

abstract:
  We study the formation and evolution of voids in the dark matter distribution
using various simulations of the popular $\Lambda$ Cold Dark Matter cosmogony.
We identify voids by requiring them to be regions of space with a mean
overdensity of -0.8 or less. Each of the simulations contains thousands of
voids. The distribution of void sizes in the different simulations shows good
agreement. Voids very clearly correspond to minima in the smoothed initial
density field. We find a universal void mass profile of the form
$\rho(<r)/\rho(r_{\rm eff}) \propto \exp[(r/r_{\rm eff})^\alpha]$ where $r_{\rm
eff}$ is the effective radius of a void and $\alpha\sim 2$. The mass function
of haloes in voids is steeper than that of haloes that populate denser regions.
The abundances of void haloes seem to evolve somewhat more strongly between
redshifts $\sim 1$ and 0 than the global abundances of haloes. (abridged)


title: The CMB spectrum in Cardassian models

abstract:
  The dark energy in the Universe is described in the context of modified
Friedmann equations as a fluid parameterized by the density of dark matter and
undergoing an adiabatic expansion. This formulation is applied to the
Cardassian model. Choosing then parameters consistent with the supernova
observations, it gives a background expansion in which the cosmic temperature
fluctuations are calculated. The resulting spectrum is quite similar to what is
obtained in the standard concordance model. If the Cardassian fluid is
interpreted as a new kind of interacting dark matter, its overdensities are
driven into oscillations when the interaction energy is rising in importance.
This does not occur in a description of the Cardassian fluctuations motivated
by theories of modified gravity. There the energy of the underlying matter is
also conserved, which requires appearance of effective shear stress in the late
Universe. In both approaches that allow fluctuations the thermal power spectrum
at large scales is much too strongly enhanced by the late integrated
Sachs-Wolfe effect. With the interacting dark matter assumption, we conclude
that the Cardassian model is ruled out by observations, expect in a small
neighbourhood of the $\Lambda$CDM limit.


title: Intermediate-velocity gas observed towards the Shajn 147 SNR

abstract:
  (Abridged) We present high-resolution spectra of the interstellar NaI and
CaII absorption lines for 3 early-type stars along the line-of-sight towards
the Shajn 147 SNR. These are supplemented with far-UV aborption spectra of HD
36665 and HD 37318 recorded with the NASA FUSE satellite. The observations
reveal intermediate-velocity (IV) absorption features at V_helio = +92 km/s
towards HD 37318 and -65 & -52 km/s towards HD 36665. These IV components can
be associated with the expansion of the SNR.
  The observations suggest that the IV component at +92 km/s towards HD 37318
is composed mainly of warm and ionized gas. The two IV components observed
towards HD 36665 are likely composed of both neutral and ionized gas shells.
Highly ionized gas was detected in the OVI (1032\AA) absorption line at +40
km/s towards both stars. This hot gas component is characterized by a columnn
density ratio (N(CIV)/N(OVI) < 0.27) consistent with that predicted by current
models of evolved SNRs, but we cannot preclude its origin in the ISM.
  Column-density ratios have been derived for the IV gas components detected
towards S147, as well as for fast-moving gas observed towards two other SNRs in
order to gain some insight into the behavior of element abundances in the
disturbed interstellar gas associated with these regions. In all cases except
for Na and Ca, these elements appear to be present with near-solar abundance
ratios. (Abridged)


title:
Clues on post-Asymptotic Giant Branch Evolution and Planetary Nebulae
  Populations from the Magellanic Clouds

abstract:
  The recent HST optical images, and the optical and ultraviolet spectra, of
Magellanic planetary nebulae (PNe), together with the large data-base that has
been collected in the past decade, allows unprecedented insight in the
evolution of PNe and their central stars. In this paper we present a selection
of recent results: The analysis of PN morphology, both in the optical and
ultra-violet emission lines; the relation between nebular morphology and the
chemistry produced by stellar evolution; the direct determination of the
transition time from observations; and the study of the nature and evolutionary
stage of the components of the planetary nebula luminosity function.


title: Dark Energy - a Pedagogic Review

abstract:
  In an introductory manner, the nature of dark energy is addressed, how it is
observed and what further tests are needed to reconstruct its properties.
Several theoretical approaches to dark energy will be discussed.


title: The SuperMACHO Microlensing Survey

abstract:
  We present the first results from our next-generation microlensing survey,
the SuperMACHO project. We are using the CTIO 4m Blanco telescope and the
MOSAIC imager to carry out a search for microlensing toward the Large
Magellanic Cloud (LMC). We plan to ascertain the nature of the population
responsible for the excess microlensing rate seen by the MACHO project. Our
observing strategy is optimized to measure the differential microlensing rate
across the face of the LMC. We find this derivative to be relatively
insensitive to the details of the LMC's internal structure but a strong
discriminant between Galactic halo and LMC self lensing. In December 2003 we
completed our third year of survey operations. 2003 also marked the first year
of real-time microlensing alerts and photometric and spectroscopic followup. We
have extracted several dozen microlensing candidates, and we present some
preliminary light curves and related information. Similar to the MACHO project,
we find SNe behind the LMC to be a significant contaminant - this background
has not been completely removed from our current single-color candidate sample.
Our follow-up strategy is optimized to discriminate between SNe and true
microlensing.


title: Late States of Stellar Evolution

abstract:
  The Square Kilometer Array will have the sensitivity, spatial resolution, and
frequency resolution to provide new scientific knowledge of evolved stars. Four
basic areas of scientific exploration are enhanced by the construction of the
SKA: 1) detection and imaging of photospheric radio continuum emission and
position correlation with maser distributions, 2) imaging of thermal dust
emission around evolved stars and the detailed structures of their
circumstellar winds (again, including comparison with maser distributions), 3)
study of cm-wavelength molecular line transitions and the circumstellar
chemistry around both O-rich and C-rich evolved stars and 4) the possible
observation of polarized emission due to the influence of the magnetic fields
of AGB stars. Since this short chapter is not meant to be a review article, a
comprehensive reference list has not been generated. I have selected just one
or perhaps two references for citations where appropriate.


title: 21 cm Absorption Studies with the Square Kilometer Array

abstract:
  HI 21~cm absorption spectroscopy provides an excellent probe of the neutral
gas content of absorbing galaxies, yielding information on their kinematics,
mass, physical size and ISM conditions. The high sensitivity, unrivaled
frequency coverage and RFI suppression techniques of the SKA will enable it to
use HI absorption to study the ISM of high column density intervening systems
along thousands of lines of sight out to high redshifts. Blind SKA 21~cm
surveys will yield large, unbiased absorber samples, tracing the evolution of
normal galaxies and active galactic nuclei from $z \gtrsim 6$ to the present
epoch. It will thus be possible to directly measure the physical size and mass
of typical galaxies as a function of redshift and, hence, to test hierarchical
models of structure formation.


title: Signatures of Explosion Models for SN ~Ia & Cosmology

abstract:
  We give an overview of the current understanding of Type Ia supernovae
relevant for their use as cosmological distance indicators. We present the
physical basis to understand their homogeneity of the observed light curves and
spectra and the observed correlations. SNe Ia have been well established as
distance indicators on the 10 % level. However, the quest for the nature of the
dark energy requires improvements in the accuracy to the 2 to 3 % level, we
must understand the diversity within the SNe Ia population, and its evolution
with redshift. Based on detailed models for the progenitors, explosions, light
curves and spectra, we discuss signatures of thermonuclear explosions, and the
implications for cosmology. We emphasize the relation between LC properties and
spectra because, for local SNe~Ia, the diversity becomes apparent the
combination of spectra and LCs whereas, by enlarge, we have to for high-z
objects. At some examples, we show how we can actually probe the properties of
the progenitor, its environment, and details of the explosion physics.


title:
The Initial-Final Mass Relationship: Spectroscopy of White Dwarfs in NGC
  2099 (M37)

abstract:
  We present new observations of very faint white dwarfs (WDs) in the rich open
star cluster NGC 2099 (M37). Following deep, wide field imaging of the cluster
using CFHT, we have now obtained spectroscopic observations of candidate WDs
using both GMOS on Gemini and LRIS on Keck. Of our 24 WD candidates (all
fainter than V = 22.4), 21 are spectroscopically confirmed to be bona fide WDs,
4-5 of which are most likely field objects. Fitting 18 of the 21 WD spectra
with model atmospheres, we find that most WDs in this cluster are quite massive
(0.7-0.9 Msun), as expected given the cluster's young age (650 Myr) and, hence,
high turnoff mass (~2.4 Msun). We determine a new initial-final mass
relationship and almost double the number of existing data points from previous
studies. The results indicate that stars with initial masses between 2.8 and
3.4 Msun lose 70-75% of their mass through stellar evolution. For the first
time, we find some evidence of a metallicity dependence on the initial-final
mass relationship.


title:
The Dearth of Massive, Helium-Rich White Dwarfs in Young Open Star
  Clusters

abstract:
  Spectra have been obtained of 21 white dwarfs (WDs) in the direction of the
young, rich open star cluster NGC 2099. This represents an appreciable fraction
(>30%) of the cluster's total WD population. The mean derived mass of the
sample is 0.8 Msun - about 0.2 Msun larger than the mean seen among field WDs.
A surprising result is that all of the NGC 2099 WDs have hydrogen-rich
atmospheres (DAs) and none exhibit helium-rich ones (DBs), or any other
spectral class. The number ratio in the field at the temperatures of the NGC
2099 WDs is DA/DB ~ 3.5. While the probability of seeing no DB WDs in NGC 2099
solely by chance is ~2%, if we include WDs in other open clusters of similar
age it then becomes highly unlikely that the dearth of DB WDs in young open
clusters is just a statistical fluctuation. We explore possible reasons for the
lack of DBs in these clusters and conclude that the most promising scenario for
the DA/DB number ratio discrepancy in young clusters is that hot, high-mass WDs
do not develop large enough helium convection zones to allow helium to be
brought to the surface and turn a hydrogen-rich WD into a helium-rich one.


title: The Equilibrium Structure of CDM Halos

abstract:
  Dark-matter halos are the scaffolding around which galaxies and clusters are
built. They form when the gravitational instability of primordial density
fluctuations causes regions which are denser than average to slow their cosmic
expansion, recollapse, and virialize. Understanding the equilibrium structure
of these halos is thus a prerequisite for understanding galaxy and cluster
formation. Numerical N-body simulations of structure formation from
Gaussian-random-noise initial conditions in the CDM universe find a universal
internal structure for halos. Objects as different in size and mass as dwarf
spheroidal galaxies and galaxy clusters are predicted to have halos with the
same basic structure when properly rescaled, independent of halo mass, of the
shape of the power spectrum of primordial density fluctuations, and of the
cosmological background parameters. This remarkable universality is a
fundamental prediction of the CDM model, but our knowledge is limited to the
``empirical'' N-body simulation results, with little analytical understanding.
We summarize here our attempts to fill this gap, in an effort to derive and
give physical insight to the numerical results and extend them beyond the range
of numerical simulation: (1) Simulated halos which form from highly simplified
initial conditions involving gravitational instability in a cosmological
pancake show that many of the universal properties of CDM halos are generic to
cosmological gravitational collapse and do not require Gaussian-random-noise
density fluctuations or hierarchical clustering. (2) A fluid approximation
derived from the Boltzmann equation yields an analytical theory of halo
dynamics which can explain many of the N-body results ... (abridged)


title: Spin-Orbit Resonance and the Evolution of Compact Binary Systems

abstract:
  Starting with a post-Newtonian description of compact binary systems, we
derive a set of equations that describes the evolution of the orbital angular
momentum and both spin vectors during inspiral. We find regions of phase space
that exhibit resonance behavior, characterized by small librations of the spin
vectors around a fixed orientation. Due to the loss of energy and orbital
angular momentum through radiation reaction, systems can eventually be captured
into these resonance orientations. By investigating the long-term evolution of
compact binaries with a variety of initial conditions, we find that the
distribution in parameter space can be strongly affected by resonance captures.
This has the effect of significantly reducing the size of search space for
gravitational wave sources, in turn improving the chances of detecting such
sources through methods of template matching. Furthermore, by calculating the
expected spin distribution at the end of the inspiral phase, we can predict
what are the most likely initial conditions for the plunge phase, a result of
great interest for numerical relativity calculations.


title: Peculiar Velocity and Deaberration of the Sky

abstract:
  Recent studies have found the earth's peculiar velocity to be significant in
microwave background based tests for compact cosmic topology, and modifications
to these tests have been proposed. Tests of non-gaussianity, weak lensing
analysis and new tests using improved CMB data will also be sensitive to
peculiar velocity. We propose here to simplify matters by showing how to
construct a deaberrated CMB map to which any test requiring a Hubble flow
viewpoint can be applied without further complication. In a similar manner
deaberration can also be applied to object surveys used for example in
topological searches and matter distribution analysis. In particular we have
produced a revised list of objects with z > 1.0 using the NASA/IPAC
Extragalactic Database.


title: Radio emission from the Cygnus Loop and its spectral characteristics

abstract:
  We present a new sensitive 2675 MHz radio continuum map of the Cygnus Loop,
which is used in conjunction with 408 MHz, 863 MHz and 1420 MHz maps from both
the Effelsberg 100-m telescope and the DRAO Synthesis Telescope for a spectral
analysis. Between 408 MHz and 2675 MHz we find an overall integrated spectral
index of $\rm \alpha = -0.42 \pm 0.06$ ($S \sim \nu^{\alpha}$), close to
previous results. There is no indication of a spectral break in the integrated
spectrum. Spatially highly varying and rather strong spectral curvature was
previously reported, but is not confirmed on the basis of new, higher
sensitivity observations. We found spectral variations across the Cygnus Loop
reaching up to $\Delta\alpha = 0.2$ from a TT-plot analysis. The flattest
spectra are seen towards enhanced emission areas. Spectral index maps produced
between different frequency pairs, as well as all four maps, revealed that
there are at least three flat spectrum regions. In regions interior to the high
emission filaments, we have detected at least two spectral components across
the whole object with $\alpha=-0.4$ and $\alpha=-0.6$ towards northern and
southern parts of the object, respectively.


title: Cluster mergers, core oscillations, and cold fronts

abstract:
  We use numerical simulations with hydrodynamics to demonstrate that a class
of cold fronts in galaxy clusters can be attributed to oscillations of the dark
matter distribution. The oscillations are initiated by the off-axis passage of
a low-mass substructure. From the simulations, we derive three observable
morphological features indicative of oscillations: 1) The existence of
compressed isophotes; 2) The regions of compression must be alternate (opposite
and staggered) and lie on an axis passing through the center of the cluster; 3)
The gradient of each compression region must pass through the center of the
cluster. Four of six clusters reported in the literature to have cold fronts
have morphologies consistent with the presence of oscillations. The clusters
with oscillations are A496, A1795, A2142, and RX J1720.1+2638. Galaxy clusters
A2256 and A3667 are not consistent so the cold fronts are interpreted as group
remnants. The oscillations may be able to provide sufficient energy to solve
the cooling-flow problem and, importantly, provide it over an extended
duration.


title:
Ultracool Subdwarfs: Metal-poor Stars and Brown Dwarfs Extending into
  the Late-type M, L and T Dwarf Regimes

abstract:
  Recent discoveries from red optical proper motion and wide-field
near-infrared surveys have uncovered a new population of ultracool subdwarfs --
metal-poor stars and brown dwarfs extending into the late-type M, L and
possibly T spectral classes. These objects are among the first low-mass stars
and brown dwarfs formed in the Galaxy, and are valuable tracers of metallicity
effects in low-temperature atmospheres. Here we review the spectral,
photometric, and kinematic properties of recent discoveries. We also examine L
subdwarf classification, and discuss how a large, complete sample of substellar
halo subdwarfs could probe the star formation history of the Galaxy's
Population II. We conclude by outlining a roadmap for future work to more
thoroughly explore this old and very low-mass population.


title: Discovery of a Second L Subdwarf in the Two Micron All Sky Survey

abstract:
  I report the discovery of the second L subdwarf identified in the Two Micron
All Sky Survey, 2MASS J16262034+3925190. This high proper motion object (mu =
1.27+/-0.03 "/yr) exhibits near-infrared spectral features indicative of a
subsolar metallicity L dwarf, including strong metal hydride and H2O absorption
bands, pressure-broadened alkali lines, and blue near-infrared colors caused by
enhanced collision-induced H2 absorption. This object is of later type than any
of the known M subdwarfs, but does not appear to be as cool as the apparently
late-type sdL 2MASS 0532+8246. The radial velocity (Vrad = -260+/-35 km/s) and
estimated tangential velocity (Vtan ~ 90-210 km/s) of 2MASS 1626+3925 indicate
membership in the Galactic halo, and this source is likely near or below the
hydrogen burning minimum mass for a metal-poor star. L subdwarfs such as 2MASS
1626+3925 are useful probes of gas and condensate chemistry in low-temperature
stellar and brown dwarf atmospheres, but more examples are needed to study
these objects as a population as well as to define a rigorous classification
scheme.


title:
Deep Radio Continuum Studies with the SKA: Evolution of Radio AGN
  Populations

abstract:
  Radio emission is insensitive to dust obscuration, and the breadth of the
radio luminosity function ensures that sources are detected over a wide range
of redshifts at all radio flux densities. As a result, radio continuum
observations are an efficient and unbiased probe of both nuclear (AGN) and
star-forming activity over all cosmic epochs.
  The SKA's ``ultra-deep radio continuum surveys'' will provide the answers to
at least three key astrophysical questions: (i) the star-formation history of
the Universe, (ii) the evolution of the low-power end of the radio galaxy
luminosity function and (iii) the relationship between the radio-loud AGN,
star-formation and radio-quiet AGN phenomena.
  In this paper we discuss the AGN science that will be enabled by the deep
radio continuum studies using the SKA. It is important to recognise that the
sub-microJy SKA sky will be dominated by populations other than `radio-loud'
AGN. In this way the SKA will not only provide an unbiased tracer of the
star-formation history of the Universe but also be able to study the
populations of sources we currently describe as `radio-quiet'. To illustrate
this point we present simulations of the extragalactic radio sky based from
models of the evolution of the radio luminosity function. From these
simulations we predict typical source distributions and estimate the natural
confusion limit to ultra-faint flux density limits relevant to the science and
design goals of the SKA.


title: HCN and HCO+ emission in the disk of M31

abstract:
  We report observations made with the IRAM 30m radiotelescope in the HCN(1-0)
and HCO+(1-0) lines towards a sample of molecular complexes (GMCs) in the disk
of the Andromeda galaxy (M31). The targets were identified bright CO GMCs
selected from the IRAM 30m CO survey with various morphologies and
environments. The clouds vary in galactocentric distances from 2.4 to 15.5kpc.
The HCN and HCO+ emission is easily detected in almost all observed positions,
with line widths generally similar to the CO ones and there is a good
correlation between the two dense gas tracers. The HCO+ emission is slightly
stronger than the HCN, in particular towards GMCs with a strong star formation
activity. However the HCO+ emission is weaker than the HCN towards a quiescent
cloud in the inner part of M31, which could be due to a lower abundance of
HCO+. We derive I_HCN/I_CO ratios between 0.008 and 0.03 and I_HCO+/I_CO ratios
between less than 0.003 and 0.04. We study the radial distribution of the dense
gas in the disk of M31. Unlike our Galaxy the HCO+/CO ratio is lower in the
center of M31 than in the arms, which can be explained by both a lower
abundance of HCO+ and different conditions of excitation. Furthermore the
HCN/CO and HCO+/CO ratios appear to be higher in the inner spiral arm and
weaker in the outer arm.


title: Nonlinear Particle Acceleration at Reverse Shocks in Supernova Remnants

abstract:
  Without amplification, magnetic fields in expanding ejecta of young supernova
remnants (SNRs) will be orders of magnitude below those required to shock
accelerate thermal electrons, or ions, to relativistic energies or to produce
radio synchrotron emission at the reverse shock. The reported observations of
such emission give support to the idea that diffusive shock acceleration (DSA)
can amplify magnetic fields by large factors. Furthermore, the uncertain
character of the amplification process leaves open the possibility that ejecta
fields, while large enough to support radio emission and DSA, may be much lower
than typical interstellar medium values. We show that DSA in such low reverse
shock fields is extremely nonlinear and efficient in the production of
cosmic-ray (CR) ions, although CRs greatly in excess of mc^2 are not produced.
These nonlinear effects, which occur at the forward shock as well, are
manifested most importantly in shock compression ratios much greater than four
and cause the interaction region between the forward and reverse shocks to
become narrower, denser, and cooler than would be the case if efficient
cosmic-ray production did not occur. The changes in the SNR structure and
evolution should be clearly observable, if present, and they convey important
information on the nature of DSA and magnetic field amplification with broad
astrophysical implications.


title:
Dust Attenuation in Late-Type Galaxies. I. Effects on Bulge and Disk
  Components

abstract:
  We present results of new Monte Carlo calculations made with the DIRTY code
of radiative transfer of stellar and scattered radiation for a dusty giant
late-type galaxy like the Milky Way, which illustrate the effect of the
attenuation of stellar light by internal dust on the integrated photometry of
the individual bulge and disk components. Here we focus on the behavior of the
attenuation function, the color excess, and the fraction of light scattered or
directly transmitted towards the outside observer as a function of the total
amount of dust and the inclination of the galaxy, and the structure of the
dusty interstellar medium (ISM) of the disk. We confirm that dust attenuation
produces qualitatively and quantitatively different effects on the integrated
photometry of bulge and disk, whatever the wavelength. In addition, we find
that the structure of the dusty ISM affects more sensitively the observed
magnitudes than the observed colors of both bulge and disk. Finally, we show
that the contribution of the scattered radiation to the total monochromatic
light received by the outside observer is significant, particularly at UV
wavelengths, even for a two-phase, clumpy, dusty ISM. Thus understanding dust
scattering properties is fundamental for the interpretation of extragalactic
observations in the rest-frame UV.


title:
ULTRACAM photometry of the eclipsing cataclysmic variables XZ Eri and DV
  UMa

abstract:
  We present high-speed, three-colour photometry of the faint eclipsing
cataclysmic variables XZ Eri and DV UMa. We determine the system parameters
through two techniques: first, timings of the eclipse contact phases of the
white dwarf and bright-spot using the derivative of the light curve; and
secondly, a parameterized model of the eclipse fitted to the observed light
curve by chi-squared minimisation. For both objects, we prefer the latter
method, as it is less affected by photon noise and rapid flickering. For XZ Eri
we obtain a mass ratio q = 0.1098 +/- 0.0017 and an orbital inclination i =
80.16 +/- 0.09 degrees. For DV UMa we derive figures of q = 0.1506 +/- 0.0009
and i = 84.24 +/- 0.07 degrees. The secondary star in XZ Eri has a very low
mass Mr/Msun = 0.0842 +/- 0.0024, placing it close to the upper limit on the
mass of a brown dwarf.


title: Signature of Electron Capture in Iron-Rich Ejecta of SN 2003du

abstract:
  Late-time near-infrared and optical spectra are presented for the
normal-bright SN2003du. At about 300 days after the explosion, the emission
profiles of well isolated [FeII] lines (in particular that of the strong
1.644mu feature) trace out the global kinematic distribution of radioactive
material in the expanding. In SN2003du, the 1.644 mu [FeII] line shows a
flat-topped, profile, indicative of a thick but hollow-centered expanding
shell, rather than a strongly-peaked profile that would be expected from a
``center-filled'' distribution.Based on detailed models for exploding
Chandrasekhar mass white dwarfs, we show that the feature is consistent with
spherical explosion models.Our model predicts central region of non-radioactive
electron-capture elements up to 2500--3000km/s as a consequence of burning
under high density, and an extended region of 56Ni up to 9,000--10,000km/s.
Furthermore our analysis indicates that the 1.644mu [FeII] profile is not
consistent with strong mixing between the regions of electron- capture isotopes
and the 56Ni layers as is predicted by detailed 3D models for nuclear
deflagration fronts. We discuss the possibility that the flat-topped profile
could be produced as a result of an infrared catastrophe and conclude that such
an explanation is unlikely. We put our results in context to other SNeIa and
briefly discuss the implications of our result for the use of SNe Ia as
cosmological standard candles.


title: Meteor light curves: the relevant parameters

abstract:
  We investigate a uniform sample of 113 light curves (LCs) of meteors
collected at the Wise Observatory in November 2002 while observing the Leonid
meteor shower. We use previously defined descriptors such as the skewness F and
a recently defined pointedness parameter along with a number of other
measurable or derived quantities to explore the parameter space in search of
meaningful LC descriptors. We make extensive use of statistical techniques to
reveal links among the variables and to understand their relative importance.
In particular, we show that meteors with long-duration trails rise slowly to
their maximal brightness and also decay slowly from there while showing milder
flaring than other meteors. Early skewed LCs show a fast rise to the peak. We
show that the duration of te luminous phase of the meteor is th emost important
variable differentiating among the 2002 LCs. The skewness parameter F appears
only as the 2nd or 3rd in explaining the LC variance. We suggest that the
pointedness parameter P could possibly be useful to discriminate among meteors
from different showers, or to compare observations and model predictions.


title:
Tracing the cosmological assembly of stars and supermassive black holes
  in galaxies

abstract:
  We examine possible phenomenological constraints for the joint evolution of
supermassive black holes (SMBH) and their host spheroids. We compare all the
available observational data on the redshift evolution of the total stellar
mass and star formation rate density in the Universe with the mass and
accretion rate density evolution of supermassive black holes, estimated from
the hard X-ray selected luminosity function of quasars and active galactic
nuclei (AGN) for a given radiative efficiency, \epsilon. We assume that the
ratio of the stellar mass in spheroids to the black hole mass density evolves
as (1+z)^{-\alpha}, while the ratio of the stellar mass in disks+irregulars to
that in spheroids evolves as (1+z)^{-\beta}, and we derive constraints on
\alpha, \beta and \epsilon. We find that \alpha>0 at the more than 4-sigma
level, implying a larger black hole mass at higher redshift for a given
spheroid stellar mass. The favored values for \beta are typically negative,
suggesting that the fraction of stellar mass in spheroids decreases with
increasing redshift. This is consistent with recent determinations that show
that the mass density at high redshift is dominated by galaxies with irregular
morphology. In agreement with earlier work, we constrain \epsilon to be between
0.04 and 0.11, depending on the exact value of the local SMBH mass density, but
almost independently of \alpha and \beta.


title:
Model of the W3(OH) environment based on data for both maser and
  'quasi-thermal' methanol lines

abstract:
  In studies of the environment of massive young stellar objects, recent
progress in both observations and theory allows a unified treatment of data for
maser and 'quasi-thermal' lines. Interferometric maser images provide
information on the distribution and kinematics of masing gas on small spatial
scales. Observations of multiple masing transitions provide constraints on the
physical parameters.
  Interferometric data on 'quasi-thermal' molecular lines permits an
investigation of the overall distribution and kinematics of the molecular gas
in the vicinity of young stellar objects, including those which are deeply
embedded. Using multiple transitions of different molecules, one can obtain
good constraints on the physical and chemical parameters.
  Combining these data enables the construction of unified models, which take
into account spatial scales differing by orders of magnitude.
  Here we present such a combined analysis of the environment around the
ultracompact HII region in W3(OH). This includes the structure of the methanol
masing region, physical structure of the near vicinity of W3(OH), detection of
new masers in the large-scale shock front and embedded sources in the vicinity
of the TW young stellar object.


title:
Spatially varying mass function of MACHOs in the galactic halo and
  interpretation of microlensing results

abstract:
  The gravitational microlensing experiments in the direction of Large
Magellanic Cloud (LMC) predict a large amount of white dwarfs ($\sim 20%$)
filling the galactic halo. However, the predicted white dwarfs have not been
observed at the galactic halo. To interpret the microlensing results and
resolving the mentioned problems, we use the hypothesis of spatially varying
mass function of MACHOs, proposed by \cite{ker98} (hereafter KE). However the
KE model is not compatible with the duration distribution of events
\cite{rah04a}. Here we use more realistic power-law model of MF, $dn/dm\propto
m^{\alpha}$ for the MACHOs of halo. The index of MF in this model changes from
-2.7 for stars with $m>1 M_{\bigodot}$ at the central part of galactic halo to
the substellar regime with an upper limit of -1 at the edge of halo. We show
that in contrast to the abundant brown dwarfs of galactic halo, heavy MACHOs
can be responsible for the microlensing events in the direction of LMC.


title: Accretion Signatures from Massive Young Stellar Objects

abstract:
  High resolution (lambda / Delta-lambda = 50,000) K-band spectra of massive,
embedded, young stellar objects are presented. The present sample consists of
four massive young stars located in nascent clusters powering Galactic giant H
II regions. Emission in the 2.3 micron 2--0 vibrational--rotational bandhead of
CO is observed. A range of velocity broadened profiles seen in three of the
objects is consistent with the emission arising from a circumstellar disk seen
at various inclination angles. Br gamma spectra of the same spectral and
spatial resolution are also presented which support an accretion disk or torus
model for massive stars. In the fourth object, Br emission suggesting a
rotating torus is observed, but the CO profile is narrow, indicating that there
may be different CO emission mechanisms in massive stars and this is consistent
with earlier observations of the BN object and MWC 349. To--date, only young
massive stars of late O or early B types have been identified with clear
accretion disk signatures in such embedded clusters. Often such stars are found
in the presence of other more massive stars which are revealed by their
photospheric spectra but which exhibit no disk signatures. This suggests the
timescale for dissipating their disks is much faster than the less massive OB
stars or that the most massive stars do not form with accretion disks.


title: GZK horizon and magnetic fields

abstract:
  We discuss some aspects of the propagation of high-energy cosmic rays (CRs)
in turbulent magnetic fields, and propose a formula for the diffusion
coefficient based on accurate simulations in a wide energy range. We discuss
the transition between ballistic and diffusive regimes and the magnetic horizon
of CR sources, showing how magnetic fields of a few nG could modify the shape
of the GZK feature. Such fields would roughly be in equipartition with the
extragalactic CRs, and could build through the resonant growth of waves within
the lifetime of the universe.


title: Dynamo action in late-type giants

abstract:
  Recent numerical MHD simulations suggest that magnetic activity may occur in
late-type giants. A entire red supergiant with stellar parameters equal to
Betelgeuse was modelled in 3d with the high-order "Pencil Code". Linear
kinematic and non-linear saturated dynamo action are found and the non-linear
magnetic field saturates at a super-equipartition value, while in the linear
regime two different modes of dynamo action are found. Magnetic activity of
late-type giants, if it exists, may influence dust and wind formation and
possibly lead to the heating of the outer atmospheres of these stars.


title:
On the Saturation of Astrophysical Dynamos: Numerical Experiments with
  the No-cosines flow

abstract:
  In the context of astrophysical dynamos we illustrate that the no-cosines
flow, with zero mean helicity, can drive fast dynamo action and study the
dynamo's mode of operation during both the linear and non-linear saturation
regime: It turns out that in addition to a high growth rate in the linear
regime, the dynamo saturates at a level significantly higher than normal
turbulent dynamos, namely at exact equipartition when the magnetic Prandtl
number is on the order of unity. Visualization of the magnetic and velocity
fields at saturation will help us to understand some of the aspects of the
non-linear dynamo problem.

categories: astro-ph physics.comp-ph physics.flu-dyn physics.geo-ph physics.plasm-ph physics.space-ph


title:
Applying Magnetized Accretion-Ejection Models to Microquasars: a
  preliminary step

abstract:
  We present in this proceeding some aspects of a model that should explain the
spectral state changes observed in microquasars. In this model, ejection is
assumed to take place only in the innermost disc region where a large scale
magnetic field is anchored. Then, in opposite to conventional ADAF models, the
accretion energy can be efficiently converted in ejection and not advected
inside the horizon. We propose that changes of the disc physical state (e.g.
transition from optically thick to optically thin states) can strongly modify
the magnetic accretion-ejection structure resulting in the spectral
variability. After a short description of our scenario, we give some details
concerning the dynamically self-consistent magnetized accretion-ejection model
used in our computation. We also present some preliminary results of spectral
energy distribution.


title:
Wide-Field Imaging from Space of Early-Type Galaxies and Their Globular
  Clusters

abstract:
  Wide-field imaging from space will reveal a wealth of information about the
globular cluster systems of any galaxies in the local universe that are
observed by such a mission. Individual globular clusters around galaxies in the
local universe have compact sizes that are ideal for the excellent spatial
resolution afforded by space-based imaging, while systems of these globular
clusters have large spatial extent that can only be fully explored by
wide-field imaging. One example of the science return from such a study is the
determination of the major formation epoch(s) of galaxies from the ages of
their globular clusters determined via their optical to near-infrared colors. A
second example is determining the sites of metal-poor globular cluster
formation from their cosmological bias, which constrains the formation of
structures early in the universe.


title: What controls the C IV line profile in active galactic nuclei?

abstract:
  The high ionization lines in active galactic nuclei (AGN), such as C IV, tend
to be blueshifted with respect to the lower ionization lines, such as H beta,
and often show a strong blue excess asymmetry not seen in the low ionization
lines. There is accumulating evidence that the H beta profile is dominated by
gravity, and thus provides a useful estimate of the black hole mass in AGN. The
shift and asymmetry commonly seen in C IV suggest that non gravitational
effects, such as obscuration and radiation pressure, may affect the line
profile. We explore the relation between the H beta and C IV profiles using UV
spectra available for 81 of the 87 z < 0.5 PG quasars in the Boroson & Green
(BG92) sample. We find the following: (1) Narrow C IV lines (FWHM < 2000 km/s)
are rare (~2 per cent occurrence rate) compared to narrow H beta lines (~20 per
cent). (2) In most objects where the H beta FWHM <4000 km/s the C IV line is
broader than H beta, but the reverse is true when the H beta FWHM > 4000 km/s.
This argues against the view that C IV generally originates closer to the
center, compared to H beta.
  (3) C IV appears to provide a significantly less accurate, and possibly
biased estimate of the black hole mass in AGN, compared with H beta. (4) All
objects where C IV is strongly blueshifted and asymmetric have a high L/L_Edd,
but the reverse is not true. This suggests that a high L/L_Edd is a necessary
but not sufficient condition for generating a blueshifted asymmetric C IV
emission. (5) We also find indications for dust reddening and scattering in
`normal' AGN. In particular, PG quasars with a redder optical-UV continuum
slope show weaker C IV emission, stronger C IV absorption, and a higher optical
continuum polarization.


title: Deep Field Surveys - A Radio View

abstract:
  I present an introductory review text, focusing on recent deep field studies
using radio telescopes, including high-resolution, wide-field VLBI
observations. The nature of the faint radio source population is discussed,
taking into account complimentary data and results that are now available via
the sub-mm, IR, optical and X-ray wave-bands. New developments regarding the
increased sensitivity of VLBI and an expansion in the instruments field-of-view
are also presented. VLBI may be an important tool in recognising distant,
obscured AGN from the ``contaminant'' star forming galaxies that now dominate
lower-resolution, sub-arcsecond and arcsecond radio observations.


title: Effect of Hot Baryons on the Weak-Lensing Shear Power Spectrum

abstract:
  We investigate the impact of the intracluster medium on the weak-lensing
shear power spectrum (PS). Using a halo model we find that, compared to the
dark matter only case, baryonic pressure leads to a suppression of the shear PS
on the order of a few percent or more for $l \gtrsim 1000$. Cooling/cooled
baryons and the intergalactic medium can further alter the shear PS. Therefore,
the interpretation of future precision weak lensing data at high multipoles
must take into account the effects of baryons.


title: A Period and a Prediction for the Of?p Spectrum Alternator HD 191612

abstract:
  The observational picture of the enigmatic O-type spectrum variable HD191612
has been sharpened substantially. A symmetrical, low-amplitude light curve with
a period near 540 d has recently been reported from Hipparcos photometry. This
period satisfies all of the spectroscopy since at least 1982, including
extensive new observations during 2003 and 2004, and it has predicted the next
transition during September--October 2004. Measurements of the H alpha
equivalent width reveal a sharp emission peak in the phase diagram, in contrast
to the apparently sinusoidal light curve. The He II absorption-line strength is
essentially constant, while He I varies strongly, possibly filled in by
emission in the O6 state, thus producing the apparent spectral-type variations.
The O8 state appears to be the "normal" one. Two intermediate O7 observations
have been obtained, which fall at the expected phases, but these are the only
modern observations of the transitions so far. The period is too long for
rotation or pulsation; although there is no direct evidence as yet for a
companion, a model in which tidally induced oscillations drive an enhanced wind
near periastron of an eccentric orbit appears promising. Further observations
during the now predictable transitions may provide a critical test. Ultraviolet
and X-ray observations during both states will likely also prove illuminating.


title: First spectra of the W UMa system V524 Monocerotis

abstract:
  We present the first high-resolution spectra of the W UMa contact binary V524
Mon. The spectra of the two components are very similar, resembling a G5 and a
K0. We find the radial velocities and rotational velocities consistent with
corotation. We estimate the radii and the masses and derive a mass ratio
M_2/M_1 = 2.1. We confirm that V524 Mon is a W-type contact system, likely
enclosed in a common convective envelope, as found by Samec & Loflin (2003). We
do not find evidence for the expected level of emission in the chromospheric
CaII H and K lines, neither H_alpha, indicating that the magnetic activity is
much weaker than expected or that other processes are hampering chromospheric
emission.


title: The Mass Function and Average Mass Loss Rate of Dark Matter Subhaloes

abstract:
  We present a simple, semi-analytical model to compute the mass functions of
dark matter subhaloes. The masses of subhaloes at their time of accretion are
obtained from a standard merger tree. During the subsequent evolution, the
subhaloes experience mass loss due to the combined effect of dynamical
friction, tidal stripping, and tidal heating. Rather than integrating these
effects along individual subhalo orbits, we consider the average mass loss
rate, where the average is taken over all possible orbital configurations. This
allows us to write the average mass loss rate as a simple function that depends
only on redshift and on the instantaneous mass ratio of subhalo and parent
halo. After calibrating the model by matching the subhalo mass function (SHMF)
of cluster-sized dark matter haloes obtained from numerical simulations, we
investigate the predicted mass and redshift dependence of the SHMF.We find
that, contrary to previous claims, the subhalo mass function is not universal.
Instead, both the slope and the normalization depend on the ratio of the parent
halo mass, M, and the characteristic non-linear mass M*. This simply reflects a
halo formation time dependence; more massive parent haloes form later, thus
allowing less time for mass loss to operate. We analyze the halo-to-halo
scatter, and show that the subhalo mass fraction of individual haloes depends
most strongly on their accretion history in the last Gyr. Finally we provide a
simple fitting function for the average SHMF of a parent halo of any mass at
any redshift and for any cosmology, and briefly discuss several implications of
our findings.


title:
Atomic data from the Iron Project.LVIII. New radiative transition
  probabilities for Fe IV including fine structure

abstract:
  We present new calculations for transition probabilities of Fe IV, with much
more extensive datasets than heretofore available. The large-scale close
coupling R-matrix calculations yield 1,798 LS bound states with n $\leq$ 11 and
$l \leq$ 9, and corresponding transition probabilities for 138,121 dipole
allowed transitions in the form of oscillator strengths $f$, line strengths
$S$, and A-coeffficients for a variety of applications. This represents the
largest R-matrix dataset in LS coupling for any ion under either the Opacity
Project or the Iron Project. Through algebraic transformation of the LS
multiplets, a total of 712,120 dipole allowed fine structure transitions for Fe
IV are obtained. Observed transition energies are used together with the energy
independent line strengths to derive the $f$- and the $A$-values; the adopted
algorithm used calculated energies for the remainder. Present results show
significantly better accuracy for the important low-lying states than previous
calculations. Monochromatic and mean opacities for Fe IV are computed and
compared with those obtained using the Opacity Project data. We find
differences which could have important consequences for several astrophysical
applications involving low ionization stages of iron.


title: Dynamic Tides and the Evolution of Stars in Close Binaries

abstract:
  In this talk, we review some recent advances in the theory of dynamic tides
in close binaries. We particularly focus on the effects of resonances of
dynamic tides with free oscillation modes and on the role of dynamic tides in
the comparison of theoretically predicted and observationally inferred
apsidal-motion rates.


title: Probing the Eclipse of J0737-3039A with Scintillation

abstract:
  We have examined the interstellar scintillations of the pulsars in the double
pulsar binary system. Near the time of the eclipse of pulsar A by the
magnetosphere of B, the scintillations from both pulsars should be highly
correlated because the radiation is passing through the same interstellar
plasma. We report confirmation of this effect using 820 and 1400 MHz
observations made with the Green Bank Telescope. The correlation allows us to
constrain the projected relative position of the two pulsars at closest
approach to be 4000 +/- 2000 km, corresponding to an inclination that is only
0.29 +/-0.14 degrees away from 90 degrees. It also produces a two-dimensional
map of the spatial correlation of the interstellar scintillation. This shows
that the interstellar medium in the direction of the pulsars is significantly
anisotropic. When this anisotropy is included in the orbital fitting, the
transverse velocity of the center of mass is reduced from the previously
published value of 141 +/- 8.5 km/s to 66 +/- 15 km/s.


title:
21 cm Tomography of the High-Redshift Universe with the Square Kilometer
  Array

abstract:
  We discuss the prospects for ``tomography'' of the intergalactic medium (IGM)
at high redshifts using the 21 cm transition of neutral hydrogen. Existing
observational constraints on the epoch of reionization imply a complex
ionization history that may require multiple generations of sources. The 21 cm
transition provides a unique tool to probe this era in detail, because it does
not suffer from saturation effects, retains full redshift information, and
directly probes the IGM gas. Observations in the redshifted 21cm line will
allow one to study the history and morphology of reionization in detail.
Depending on the characteristics of the first sources, they may also allow us
to probe the era before reionization, when the first structures and luminous
sources were forming. The construction of high signal-to-noise ratio maps on
arcminute scales will require approximately one square kilometer of collecting
area.


title: The Radio Variability of the Gravitational Lens PMN J1838-3427

abstract:
  We present the results of a radio variability study of the gravitational lens
PMN J1838-3427. Our motivation was to determine the Hubble constant by
measuring the time delay between variations of the two quasar images. We
monitored the system for 4 months (approximately 5 times longer than the
expected delay) using the Australia Telescope Compact Array at 9 GHz. Although
both images were variable on a time scale of a few days, no correlated
intrinsic variability could be identified, and therefore no time delay could be
measured. Notably, the fractional variation of the fainter image (8%) was
greater than that of the brighter image (4%), whereas lensed images of a point
source would have the same fractional variation. This effect can be explained,
at least in part, as the refractive scintillation of both images due to the
turbulent interstellar medium of the Galaxy.


title: Dark energy reflections in the redshift-space quadrupole

abstract:
  We show that the redshift-space quadrupole will be a powerful tool for
constraining dark energy even if the baryon oscillations are missing from the
usual monopole power spectrum and even if bias is scale- and time-dependent. We
calculate the accuracy with which a next-generation galaxy survey based on KAOS
will measure the quadrupole power spectrum, which gives the leading
anisotropies in the power spectrum in redshift space due to the linear
velocity, Finger of God and Alcock-Paczynski effects. Combining the monopole
and quadrupole power spectra breaks the degeneracies between the multiple bias
parameters and dark energy both in the linear and nonlinear regimes and, in the
complete absence of baryon oscillations ($\Omega_b=0$), leads to a roughly 500%
improvement in constraints on dark energy compared with those from the monopole
spectrum alone. As a result the worst case - with no baryon oscillations - has
dark energy errors only mildly degraded relative to the ideal case, providing
insurance on the robustness of next-generation galaxy survey constraints on
dark energy.


title: Are Magnetic Wind-Driving Disks Inherently Unstable?

abstract:
  There have been claims in the literature that accretion disks in which a
centrifugally driven wind is the dominant mode of angular momentum transport
are inherently unstable. This issue is considered here by applying an
equilibrium-curve analysis to the wind-driving, ambipolar diffusion-dominated,
magnetic disk model of Wardle & Konigl (1993). The equilibrium solution curves
for this class of models typically exhibit two distinct branches. It is argued
that only one of these branches represents unstable equilibria and that a real
disk/wind system likely corresponds to a stable solution.


title: Neutral Hydrogen in the Interacting Magellanic Spirals NGC 4618/4625

abstract:
  Asymmetry is a common trait in spiral galaxies and is particularly frequent
among Magellanic spirals. To explore how morphological and kinematic asymmetry
are affected by companion galaxies, we analyze neutral hydrogen observations of
the interacting Magellanic spirals NGC 4618 and 4625. The analysis of the H I
distribution revealed that about 10% of the total H I mass of NGC 4618 resides
in a looping tidal structure that appears to wrap all the way around the
galaxy. Through calculations based on derived H I profiles, we show that NGC
4618 and 4625 are no more asymmetric than non-interacting Magellanic spirals
analyzed by Wilcots & Prescott (2004). We also derive rotation curves for the
approaching and receding sides of each galaxy. By fitting the mean curves with
an isothermal halo model, we calculate dynamical masses of 4.7 times 10^{9}
M_sun and 9.8 times 10^{9} M_sun out to 6.7 kpc, for NGC 4618 and 4625
respectively. While the rotation curves had systematically higher velocities on
the receding side of each galaxy, the effect was no more pronounced than in
studies of non-interacting spirals (Swaters et. al. 1999). The degree of
interaction-driven asymmetry in both galaxies is indistinguishable from the
intrinsic degree of asymmetry of lopsided galaxies.